701
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Martirez JMP, Carter EA. Prediction of a low-temperature N 2 dissociation catalyst exploiting near-IR-to-visible light nanoplasmonics. Sci Adv 2017; 3:eaao4710. [PMID: 29291247 PMCID: PMC5744471 DOI: 10.1126/sciadv.aao4710] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/20/2017] [Indexed: 05/27/2023]
Abstract
Despite more than a century of advances in catalyst and production plant design, the Haber-Bosch process for industrial ammonia (NH3) synthesis still requires energy-intensive high temperatures and pressures. We propose taking advantage of sunlight conversion into surface plasmon resonances in Au nanoparticles to enhance the rate of the N2 dissociation reaction, which is the bottleneck in NH3 production. We predict that this can be achieved through Mo doping of the Au surface based on embedded multireference correlated wave function calculations. The Au component serves as a light-harvesting antenna funneling energy onto the Mo active site, whereby excited-state channels (requiring 1.4 to 1.45 eV, near-infrared-to-visible plasmon resonances) may be accessed. This effectively lowers the energy barriers to 0.44 to 0.77 eV/N2 (43 to 74 kJ/mol N2) from 3.5 eV/N2 (335 kJ/mol N2) in the ground state. The overall process requires three successive surface excitation events, which could be facilitated by amplified resonance energy transfer due to plasmon local field enhancement.
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Affiliation(s)
- John Mark P. Martirez
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544–5263, USA
| | - Emily A. Carter
- School of Engineering and Applied Science, Princeton University, Princeton, NJ 08544–5263, USA
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702
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Wilts BD, Vey AJM, Briscoe AD, Stavenga DG. Longwing (Heliconius) butterflies combine a restricted set of pigmentary and structural coloration mechanisms. BMC Evol Biol 2017; 17:226. [PMID: 29162029 PMCID: PMC5699198 DOI: 10.1186/s12862-017-1073-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 11/15/2017] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Longwing butterflies, Heliconius sp., also called heliconians, are striking examples of diversity and mimicry in butterflies. Heliconians feature strongly colored patterns on their wings, arising from wing scales colored by pigments and/or nanostructures, which serve as an aposematic signal. RESULTS Here, we investigate the coloration mechanisms among several species of Heliconius by applying scanning electron microscopy, (micro)spectrophotometry, and imaging scatterometry. We identify seven kinds of colored scales within Heliconius whose coloration is derived from pigments, nanostructures or both. In yellow-, orange- and red-colored wing patches, both cover and ground scales contain wavelength-selective absorbing pigments, 3-OH-kynurenine, xanthommatin and/or dihydroxanthommatin. In blue wing patches, the cover scales are blue either due to interference of light in the thin-film lower lamina (e.g., H. doris) or in the multilayered lamellae in the scale ridges (so-called ridge reflectors, e.g., H. sara and H. erato); the underlying ground scales are black. In the white wing patches, both cover and ground scales are blue due to their thin-film lower lamina, but because they are stacked upon each other and at the wing substrate, a faint bluish to white color results. Lastly, green wing patches (H. doris) have cover scales with blue-reflecting thin films and short-wavelength absorbing 3-OH-kynurenine, together causing a green color. CONCLUSIONS The pigmentary and structural traits are discussed in relation to their phylogenetic distribution and the evolution of vision in this highly interesting clade of butterflies.
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Affiliation(s)
- Bodo D Wilts
- Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747AG, Groningen, The Netherlands.
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700, Fribourg, Switzerland.
| | - Aidan J M Vey
- Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747AG, Groningen, The Netherlands
| | - Adriana D Briscoe
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, 92697, USA
| | - Doekele G Stavenga
- Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747AG, Groningen, The Netherlands
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703
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Abstract
This article presents the results of an experiment, called the ABA experiment, designed to test a fundamental prediction of quantum probability theory when applied to human judgments and decisions. The prediction concerns the effect of one measurement on another when the measurements are incompatible (i.e., the answers to the measurements depend on the order of these measurements). After an initial measurement of an opinion on an issue, A, the answer to a second measurement on the same issue A immediately afterwards will certainly be the same as the first. However, according to the uncertainty principle, if a measurement of opinion on issue A is followed by an incompatible measurement on another issue, B, then the answer to a second measurement on issue A will become uncertain. This prediction was tested with 325 participants on a wide range of 12 different set of issues that were previously shown to be incompatible. Contrary to previous claims published in this journal, the empirical findings support the prediction of quantum probability theory applied to human judgments.
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Affiliation(s)
- Jerome Busemeyer
- Psychological and Brain Sciences/Indiana University, Bloomington, Indiana, United States of America
- * E-mail:
| | - Zheng Wang
- School of Communication, Transitional Data Analytics Institute /The Ohio State University, Columbus, Ohio, United States of America
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704
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de Busserolles F, Cortesi F, Helvik JV, Davies WIL, Templin RM, Sullivan RKP, Michell CT, Mountford JK, Collin SP, Irigoien X, Kaartvedt S, Marshall J. Pushing the limits of photoreception in twilight conditions: The rod-like cone retina of the deep-sea pearlsides. Sci Adv 2017; 3:eaao4709. [PMID: 29134201 PMCID: PMC5677336 DOI: 10.1126/sciadv.aao4709] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 10/17/2017] [Indexed: 06/07/2023]
Abstract
Most vertebrates have a duplex retina comprising two photoreceptor types, rods for dim-light (scotopic) vision and cones for bright-light (photopic) and color vision. However, deep-sea fishes are only active in dim-light conditions; hence, most species have lost their cones in favor of a simplex retina composed exclusively of rods. Although the pearlsides, Maurolicus spp., have such a pure rod retina, their behavior is at odds with this simplex visual system. Contrary to other deep-sea fishes, pearlsides are mostly active during dusk and dawn close to the surface, where light levels are intermediate (twilight or mesopic) and require the use of both rod and cone photoreceptors. This study elucidates this paradox by demonstrating that the pearlside retina does not have rod photoreceptors only; instead, it is composed almost exclusively of transmuted cone photoreceptors. These transmuted cells combine the morphological characteristics of a rod photoreceptor with a cone opsin and a cone phototransduction cascade to form a unique photoreceptor type, a rod-like cone, specifically tuned to the light conditions of the pearlsides' habitat (blue-shifted light at mesopic intensities). Combining properties of both rods and cones into a single cell type, instead of using two photoreceptor types that do not function at their full potential under mesopic conditions, is likely to be the most efficient and economical solution to optimize visual performance. These results challenge the standing paradigm of the function and evolution of the vertebrate duplex retina and emphasize the need for a more comprehensive evaluation of visual systems in general.
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Affiliation(s)
- Fanny de Busserolles
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jon Vidar Helvik
- Department of Biology, University of Bergen, Bergen 5020, Norway
| | - Wayne I. L. Davies
- The Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
- School of Biological Science, The University of Western Australia, Crawley, Western Australia 6009, Australia
- Lions Eye Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Rachel M. Templin
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Robert K. P. Sullivan
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Craig T. Michell
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Department of Environmental and Biological Sciences, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Jessica K. Mountford
- The Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
- School of Biological Science, The University of Western Australia, Crawley, Western Australia 6009, Australia
- Lions Eye Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Shaun P. Collin
- The Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
- School of Biological Science, The University of Western Australia, Crawley, Western Australia 6009, Australia
- Lions Eye Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Xabier Irigoien
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Marine Research, AZTI - Tecnalia, Herrera Kaia, Portualdea z/g, 20110 Pasaia (Gipuzkoa), Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Stein Kaartvedt
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Department of Biosciences, University of Oslo, Oslo 0316, Norway
| | - Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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705
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Rendall AD, Sontag ED. Multiple steady states and the form of response functions to antigen in a model for the initiation of T-cell activation. R Soc Open Sci 2017; 4:170821. [PMID: 29291072 PMCID: PMC5717646 DOI: 10.1098/rsos.170821] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/06/2017] [Indexed: 06/07/2023]
Abstract
The aim of this paper is to study the qualitative behaviour predicted by a mathematical model for the initial stage of T-cell activation. The state variables in the model are the concentrations of phosphorylation states of the T-cell receptor (TCR) complex and the phosphatase SHP-1 in the cell. It is shown that these quantities cannot approach zero and that the model possesses more than one positive steady state for certain values of the parameters. It can also exhibit damped oscillations. It is proved that the chemical concentration which represents the degree of activation of the cell, that of the maximally phosphorylated form of the TCR complex, is, in general, a non-monotone function of the activating signal. In particular, there are cases where there is a value of the dissociation constant of the ligand from the receptor which produces a maximal activation of the T cell. This suggests that mechanisms taking place in the first few minutes after activation and included in the model studied in this paper suffice to explain the optimal dissociation time seen in experiments. In this way, the results of certain simulations in the literature have been confirmed rigorously and some important features which had not previously been seen have been discovered.
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Affiliation(s)
- Alan D. Rendall
- Institut für Mathematik, Johannes Gutenberg-Universität, Staudingerweg 9, D-55099 Mainz, Germany
| | - Eduardo D. Sontag
- Department of Mathematics and the Center for Quantitative Biology, Rutgers University, Piscataway, NJ 08854, USA
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706
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Fitak RR, Johnsen S. Bringing the analysis of animal orientation data full circle: model-based approaches with maximum likelihood. J Exp Biol 2017; 220:3878-3882. [PMID: 28860118 PMCID: PMC6514460 DOI: 10.1242/jeb.167056] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 08/25/2017] [Indexed: 11/20/2022]
Abstract
In studies of animal orientation, data are often represented as directions that can be analyzed using circular statistical methods. Although several circular statistical tests exist to detect the presence of a mean direction, likelihood-based approaches may offer advantages in hypothesis testing - especially when data are multimodal. Unfortunately, likelihood-based inference in animal orientation remains rare. Here, we discuss some of the assumptions and limitations of common circular tests and report a new R package called CircMLE to implement the maximum likelihood analysis of circular data. We illustrate the use of this package on both simulated datasets and an empirical example dataset in Chinook salmon (Oncorhynchus tshawytscha). Our software provides a convenient interface that facilitates the use of model-based approaches in animal orientation studies.
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Affiliation(s)
- Robert R Fitak
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Sönke Johnsen
- Department of Biology, Duke University, Durham, NC 27708, USA
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707
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Calabrese EJ. A glance into how the cold war and governmental loyalty investigations came to affect a leading U.S. radiation geneticist: Lewis J. Stadler's nightmare. Philos Ethics Humanit Med 2017; 12:8. [PMID: 29082852 PMCID: PMC5662100 DOI: 10.1186/s13010-017-0050-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/20/2017] [Indexed: 06/07/2023] Open
Abstract
This paper describes an episode in the life of the prominent plant radiation geneticist, Lewis J. Stadler (1897-1954) during which he became a target of the Federal Bureau of Investigation (FBI) concerning loyalty to the United States due to possible associations with the communist party. The research is based on considerable private correspondence of Dr. Stadler, the FBI interrogatory questions and Dr. Stadler's answers and letters of support for Dr. Stadler by leading scientists such as, Hermann J. Muller.
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Affiliation(s)
- Edward J Calabrese
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Morrill I, N344, Amherst, MA, 01003, USA.
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708
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Gala R, Lebrecht D, Sahlender DA, Jorstad A, Knott G, Holtmaat A, Stepanyants A. Computer assisted detection of axonal bouton structural plasticity in in vivo time-lapse images. eLife 2017; 6:e29315. [PMID: 29058678 PMCID: PMC5675596 DOI: 10.7554/elife.29315] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/22/2017] [Indexed: 11/16/2022] Open
Abstract
The ability to measure minute structural changes in neural circuits is essential for long-term in vivo imaging studies. Here, we propose a methodology for detection and measurement of structural changes in axonal boutons imaged with time-lapse two-photon laser scanning microscopy (2PLSM). Correlative 2PLSM and 3D electron microscopy (EM) analysis, performed in mouse barrel cortex, showed that the proposed method has low fractions of false positive/negative bouton detections (2/0 out of 18), and that 2PLSM-based bouton weights are correlated with their volumes measured in EM (r = 0.93). Next, the method was applied to a set of axons imaged in quick succession to characterize measurement uncertainty. The results were used to construct a statistical model in which bouton addition, elimination, and size changes are described probabilistically, rather than being treated as deterministic events. Finally, we demonstrate that the model can be used to quantify significant structural changes in boutons in long-term imaging experiments.
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Affiliation(s)
- Rohan Gala
- Department of Physics and Center for Interdisciplinary Research on Complex SystemsNortheastern UniversityBostonUnited States
| | - Daniel Lebrecht
- Department of Basic Neurosciences, Faculty of MedicineUniversity of GenevaGenevaSwitzerland
- Lemanic Neuroscience Doctoral SchoolSwitzerland
| | - Daniela A Sahlender
- Biological Electron Microscopy Facility, Centre of Electron MicroscopyÉcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Anne Jorstad
- Biological Electron Microscopy Facility, Centre of Electron MicroscopyÉcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Graham Knott
- Biological Electron Microscopy Facility, Centre of Electron MicroscopyÉcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Anthony Holtmaat
- Department of Basic Neurosciences, Faculty of MedicineUniversity of GenevaGenevaSwitzerland
| | - Armen Stepanyants
- Department of Physics and Center for Interdisciplinary Research on Complex SystemsNortheastern UniversityBostonUnited States
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709
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Nandi A, Schättler H, Ritt JT, Ching S. Fundamental Limits of Forced Asynchronous Spiking with Integrate and Fire Dynamics. J Math Neurosci 2017; 7:11. [PMID: 29022250 PMCID: PMC5636789 DOI: 10.1186/s13408-017-0053-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 09/25/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Anirban Nandi
- Electrical and Systems Engineering, Washington University in St. Louis, St. Louis, MO USA
| | - Heinz Schättler
- Electrical and Systems Engineering, Washington University in St. Louis, St. Louis, MO USA
| | - Jason T. Ritt
- Department of Biomedical Engineering, Boston University, Boston, MA USA
| | - ShiNung Ching
- Electrical and Systems Engineering, Washington University in St. Louis, St. Louis, MO USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO USA
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710
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Linke NM, Gutierrez M, Landsman KA, Figgatt C, Debnath S, Brown KR, Monroe C. Fault-tolerant quantum error detection. Sci Adv 2017; 3:e1701074. [PMID: 29062889 PMCID: PMC5650489 DOI: 10.1126/sciadv.1701074] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 09/21/2017] [Indexed: 05/22/2023]
Abstract
Quantum computers will eventually reach a size at which quantum error correction becomes imperative. Quantum information can be protected from qubit imperfections and flawed control operations by encoding a single logical qubit in multiple physical qubits. This redundancy allows the extraction of error syndromes and the subsequent detection or correction of errors without destroying the logical state itself through direct measurement. We show the encoding and syndrome measurement of a fault-tolerantly prepared logical qubit via an error detection protocol on four physical qubits, represented by trapped atomic ions. This demonstrates the robustness of a logical qubit to imperfections in the very operations used to encode it. The advantage persists in the face of large added error rates and experimental calibration errors.
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Affiliation(s)
- Norbert M. Linke
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Mauricio Gutierrez
- Schools of Chemistry and Biochemistry, Computational Science and Engineering, and Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Kevin A. Landsman
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Caroline Figgatt
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Shantanu Debnath
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Kenneth R. Brown
- Schools of Chemistry and Biochemistry, Computational Science and Engineering, and Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Christopher Monroe
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
- IonQ Inc., College Park, MD 20742, USA
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711
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Abstract
The historical foundations of cancer risk assessment were based on the discovery of X-ray-induced gene mutations by Hermann J. Muller, its transformation into the linear nonthreshold (LNT) single-hit theory, the recommendation of the model by the US National Academy of Sciences, Biological Effects of Atomic Radiation I, Genetics Panel in 1956, and subsequent widespread adoption by regulatory agencies worldwide. This article summarizes substantial recent historical revelations of this history, which profoundly challenge the standard and widely acceptable history of cancer risk assessment, showing multiple significant scientific errors and incorrect interpretations, mixed with deliberate misrepresentation of the scientific record by leading ideologically motivated radiation geneticists. These novel historical findings demonstrate that the scientific foundations of the LNT single-hit model were seriously flawed and should not have been adopted for cancer risk assessment.
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Affiliation(s)
- Edward J. Calabrese
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Morrill I, Amherst, MA, USA
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712
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Xu W, Qin Z, Chen CT, Kwag HR, Ma Q, Sarkar A, Buehler MJ, Gracias DH. Ultrathin thermoresponsive self-folding 3D graphene. Sci Adv 2017; 3:e1701084. [PMID: 28989963 PMCID: PMC5630237 DOI: 10.1126/sciadv.1701084] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 09/12/2017] [Indexed: 05/21/2023]
Abstract
Graphene and other two-dimensional materials have unique physical and chemical properties of broad relevance. It has been suggested that the transformation of these atomically planar materials to three-dimensional (3D) geometries by bending, wrinkling, or folding could significantly alter their properties and lead to novel structures and devices with compact form factors, but strategies to enable this shape change remain limited. We report a benign thermally responsive method to fold and unfold monolayer graphene into predesigned, ordered 3D structures. The methodology involves the surface functionalization of monolayer graphene using ultrathin noncovalently bonded mussel-inspired polydopamine and thermoresponsive poly(N-isopropylacrylamide) brushes. The functionalized graphene is micropatterned and self-folds into ordered 3D structures with reversible deformation under a full control by temperature. The structures are characterized using spectroscopy and microscopy, and self-folding is rationalized using a multiscale molecular dynamics model. Our work demonstrates the potential to design and fabricate ordered 3D graphene structures with predictable shape and dynamics. We highlight applicability by encapsulating live cells and creating nonlinear resistor and creased transistor devices.
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Affiliation(s)
- Weinan Xu
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Zhao Qin
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chun-Teh Chen
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hye Rin Kwag
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Qinli Ma
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Anjishnu Sarkar
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Markus J. Buehler
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - David H. Gracias
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
- Corresponding author.
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713
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Golovin K, Tuteja A. A predictive framework for the design and fabrication of icephobic polymers. Sci Adv 2017; 3:e1701617. [PMID: 28948227 PMCID: PMC5609849 DOI: 10.1126/sciadv.1701617] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 08/28/2017] [Indexed: 05/19/2023]
Abstract
Ice accretion remains a costly, hazardous concern worldwide. Icephobic coatings reduce the adhesion between ice and a surface. However, only a handful of the icephobic systems reported to date reduce the ice adhesion sufficiently for the facile and passive removal of ice, such as under its own weight or by mild winds. Most of these icephobic surfaces have relied on sacrificial lubricants, which may be depleted over time, drastically raising the ice adhesion. In contrast, surfaces that use interfacial slippage to lower their adhesion to ice can remain icephobic indefinitely. However, the mechanism of interfacial slippage, as it relates to ice adhesion, is largely unexplored. We investigate how interfacial slippage reduces the ice adhesion of polymeric materials. We propose a new, universally applicable framework that may be used to predict the reduction in the adhesion of ice to surfaces exhibiting interfacial slippage. This framework allows one to rationally engender icephobicity in essentially any polymeric system, including common thermoplastics. Hence, we present several new, extremely icephobic systems fabricated from a wide range of materials, including everyday engineering plastics and sustainable, natural oils.
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Affiliation(s)
- Kevin Golovin
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anish Tuteja
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Corresponding author.
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714
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Liu N, Chortos A, Lei T, Jin L, Kim TR, Bae WG, Zhu C, Wang S, Pfattner R, Chen X, Sinclair R, Bao Z. Ultratransparent and stretchable graphene electrodes. Sci Adv 2017; 3:e1700159. [PMID: 28913422 PMCID: PMC5590784 DOI: 10.1126/sciadv.1700159] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 08/09/2017] [Indexed: 05/21/2023]
Abstract
Two-dimensional materials, such as graphene, are attractive for both conventional semiconductor applications and nascent applications in flexible electronics. However, the high tensile strength of graphene results in fracturing at low strain, making it challenging to take advantage of its extraordinary electronic properties in stretchable electronics. To enable excellent strain-dependent performance of transparent graphene conductors, we created graphene nanoscrolls in between stacked graphene layers, referred to as multilayer graphene/graphene scrolls (MGGs). Under strain, some scrolls bridged the fragmented domains of graphene to maintain a percolating network that enabled excellent conductivity at high strains. Trilayer MGGs supported on elastomers retained 65% of their original conductance at 100% strain, which is perpendicular to the direction of current flow, whereas trilayer films of graphene without nanoscrolls retained only 25% of their starting conductance. A stretchable all-carbon transistor fabricated using MGGs as electrodes exhibited a transmittance of >90% and retained 60% of its original current output at 120% strain (parallel to the direction of charge transport). These highly stretchable and transparent all-carbon transistors could enable sophisticated stretchable optoelectronics.
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Affiliation(s)
- Nan Liu
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Alex Chortos
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Ting Lei
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Lihua Jin
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA
| | - Taeho Roy Kim
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Won-Gyu Bae
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Chenxin Zhu
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Sihong Wang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Raphael Pfattner
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Xiyuan Chen
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Robert Sinclair
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Corresponding author:
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715
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Farazmand M, Sapsis TP. A variational approach to probing extreme events in turbulent dynamical systems. Sci Adv 2017; 3:e1701533. [PMID: 28948226 PMCID: PMC5609843 DOI: 10.1126/sciadv.1701533] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 08/29/2017] [Indexed: 06/07/2023]
Abstract
Extreme events are ubiquitous in a wide range of dynamical systems, including turbulent fluid flows, nonlinear waves, large-scale networks, and biological systems. We propose a variational framework for probing conditions that trigger intermittent extreme events in high-dimensional nonlinear dynamical systems. We seek the triggers as the probabilistically feasible solutions of an appropriately constrained optimization problem, where the function to be maximized is a system observable exhibiting intermittent extreme bursts. The constraints are imposed to ensure the physical admissibility of the optimal solutions, that is, significant probability for their occurrence under the natural flow of the dynamical system. We apply the method to a body-forced incompressible Navier-Stokes equation, known as the Kolmogorov flow. We find that the intermittent bursts of the energy dissipation are independent of the external forcing and are instead caused by the spontaneous transfer of energy from large scales to the mean flow via nonlinear triad interactions. The global maximizer of the corresponding variational problem identifies the responsible triad, hence providing a precursor for the occurrence of extreme dissipation events. Specifically, monitoring the energy transfers within this triad allows us to develop a data-driven short-term predictor for the intermittent bursts of energy dissipation. We assess the performance of this predictor through direct numerical simulations.
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716
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Miyata K, Meggiolaro D, Trinh MT, Joshi PP, Mosconi E, Jones SC, De Angelis F, Zhu XY. Large polarons in lead halide perovskites. Sci Adv 2017; 3:e1701217. [PMID: 28819647 PMCID: PMC5553817 DOI: 10.1126/sciadv.1701217] [Citation(s) in RCA: 245] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/12/2017] [Indexed: 05/19/2023]
Abstract
Lead halide perovskites show marked defect tolerance responsible for their excellent optoelectronic properties. These properties might be explained by the formation of large polarons, but how they are formed and whether organic cations are essential remain open questions. We provide a direct time domain view of large polaron formation in single-crystal lead bromide perovskites CH3NH3PbBr3 and CsPbBr3. We found that large polaron forms predominantly from the deformation of the PbBr3- frameworks, irrespective of the cation type. The difference lies in the polaron formation time, which, in CH3NH3PbBr3 (0.3 ps), is less than half of that in CsPbBr3 (0.7 ps). First-principles calculations confirm large polaron formation, identify the Pb-Br-Pb deformation modes as responsible, and explain quantitatively the rate difference between CH3NH3PbBr3 and CsPbBr3. The findings reveal the general advantage of the soft [PbX3]- sublattice in charge carrier protection and suggest that there is likely no mechanistic limitations in using all-inorganic or mixed-cation lead halide perovskites to overcome instability problems and to tune the balance between charge carrier protection and mobility.
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Affiliation(s)
- Kiyoshi Miyata
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Daniele Meggiolaro
- Computational Laboratory for Hybrid/Organic Photovoltaics, National Research Council–Institute of Molecular Science and Technologies, Via Elce di Sotto 8, I-06123 Perugia, Italy
- D3-CompuNet, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - M. Tuan Trinh
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Prakriti P. Joshi
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Edoardo Mosconi
- Computational Laboratory for Hybrid/Organic Photovoltaics, National Research Council–Institute of Molecular Science and Technologies, Via Elce di Sotto 8, I-06123 Perugia, Italy
- D3-CompuNet, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Skyler C. Jones
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Filippo De Angelis
- Computational Laboratory for Hybrid/Organic Photovoltaics, National Research Council–Institute of Molecular Science and Technologies, Via Elce di Sotto 8, I-06123 Perugia, Italy
- D3-CompuNet, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- Corresponding author. (X.-Y.Z.); (F.D.A.)
| | - X.-Y. Zhu
- Department of Chemistry, Columbia University, New York, NY 10027, USA
- Corresponding author. (X.-Y.Z.); (F.D.A.)
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717
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Mleczko MJ, Zhang C, Lee HR, Kuo HH, Magyari-Köpe B, Moore RG, Shen ZX, Fisher IR, Nishi Y, Pop E. HfSe 2 and ZrSe 2: Two-dimensional semiconductors with native high-κ oxides. Sci Adv 2017; 3:e1700481. [PMID: 28819644 PMCID: PMC5553816 DOI: 10.1126/sciadv.1700481] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 07/12/2017] [Indexed: 05/21/2023]
Abstract
The success of silicon as a dominant semiconductor technology has been enabled by its moderate band gap (1.1 eV), permitting low-voltage operation at reduced leakage current, and the existence of SiO2 as a high-quality "native" insulator. In contrast, other mainstream semiconductors lack stable oxides and must rely on deposited insulators, presenting numerous compatibility challenges. We demonstrate that layered two-dimensional (2D) semiconductors HfSe2 and ZrSe2 have band gaps of 0.9 to 1.2 eV (bulk to monolayer) and technologically desirable "high-κ" native dielectrics HfO2 and ZrO2, respectively. We use spectroscopic and computational studies to elucidate their electronic band structure and then fabricate air-stable transistors down to three-layer thickness with careful processing and dielectric encapsulation. Electronic measurements reveal promising performance (on/off ratio > 106; on current, ~30 μA/μm), with native oxides reducing the effects of interfacial traps. These are the first 2D materials to demonstrate technologically relevant properties of silicon, in addition to unique compatibility with high-κ dielectrics, and scaling benefits from their atomically thin nature.
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Affiliation(s)
- Michal J. Mleczko
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Chaofan Zhang
- Department of Physics, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Hye Ryoung Lee
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Hsueh-Hui Kuo
- Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Blanka Magyari-Köpe
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Robert G. Moore
- Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Zhi-Xun Shen
- Department of Physics, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Ian R. Fisher
- Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Yoshio Nishi
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Eric Pop
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Precourt Institute for Energy, Stanford University, Stanford, CA 94305, USA
- Corresponding author.
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718
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Yang L, Craviso GL, Vernier PT, Chatterjee I, Leblanc N. Nanosecond electric pulses differentially affect inward and outward currents in patch clamped adrenal chromaffin cells. PLoS One 2017; 12:e0181002. [PMID: 28700658 PMCID: PMC5507283 DOI: 10.1371/journal.pone.0181002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 06/23/2017] [Indexed: 11/18/2022] Open
Abstract
This study examined the effect of 5 ns electric pulses on macroscopic ionic currents in whole-cell voltage-clamped adrenal chromaffin cells. Current-voltage (I-V) relationships first established that the early peak inward current was primarily composed of a fast voltage-dependent Na+ current (INa), whereas the late outward current was composed of at least three ionic currents: a voltage-gated Ca2+ current (ICa), a Ca2+-activated K+ current (IK(Ca)), and a sustained voltage-dependent delayed rectifier K+ current (IKV). A constant-voltage step protocol was next used to monitor peak inward and late outward currents before and after cell exposure to a 5 ns pulse. A single pulse applied at an electric (E)-field amplitude of 5 MV/m resulted in an instantaneous decrease of ~4% in peak INa that then declined exponentially to a level that was ~85% of the initial level after 10 min. Increasing the E-field amplitude to 8 or 10 MV/m caused a twofold greater inhibitory effect on peak INa. The decrease in INa was not due to a change in either the steady-state inactivation or activation of the Na+ channel but instead was associated with a decrease in maximal Na+ conductance. Late outward current was not affected by a pulse applied at 5 MV/m. However, for a pulse applied at the higher E-field amplitudes of 8 and 10 MV/m, late outward current in some cells underwent a progressive ~22% decline over the course of the first 20 s following pulse exposure, with no further decline. The effect was most likely concentrated on ICa and IK(Ca) as IKV was not affected. The results of this study indicate that in whole-cell patch clamped adrenal chromaffin cells, a 5 ns pulse differentially inhibits specific voltage-gated ionic currents in a manner that can be manipulated by tuning E-field amplitude.
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Affiliation(s)
- Lisha Yang
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, United States of America
| | - Gale L. Craviso
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, United States of America
| | - P. Thomas Vernier
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, United States of America
| | - Indira Chatterjee
- Department of Electrical and Biomedical Engineering, College of Engineering, University of Nevada, Reno, NV, United States of America
| | - Normand Leblanc
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, United States of America
- Center for Cardiovascular Research, University of Nevada, Reno School of Medicine, Reno, NV, United States of America
- * E-mail:
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719
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Xia Z, Song H, Kim M, Zhou M, Chang TH, Liu D, Yin X, Xiong K, Mi H, Wang X, Xia F, Yu Z, Ma Z(J, Gan Q. Single-crystalline germanium nanomembrane photodetectors on foreign nanocavities. Sci Adv 2017; 3:e1602783. [PMID: 28695202 PMCID: PMC5501504 DOI: 10.1126/sciadv.1602783] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 05/26/2017] [Indexed: 05/24/2023]
Abstract
Miniaturization of optoelectronic devices offers tremendous performance gain. As the volume of photoactive material decreases, optoelectronic performance improves, including the operation speed, the signal-to-noise ratio, and the internal quantum efficiency. Over the past decades, researchers have managed to reduce the volume of photoactive materials in solar cells and photodetectors by orders of magnitude. However, two issues arise when one continues to thin down the photoactive layers to the nanometer scale (for example, <50 nm). First, light-matter interaction becomes weak, resulting in incomplete photon absorption and low quantum efficiency. Second, it is difficult to obtain ultrathin materials with single-crystalline quality. We introduce a method to overcome these two challenges simultaneously. It uses conventional bulk semiconductor wafers, such as Si, Ge, and GaAs, to realize single-crystalline films on foreign substrates that are designed for enhanced light-matter interaction. We use a high-yield and high-throughput method to demonstrate nanometer-thin photodetectors with significantly enhanced light absorption based on nanocavity interference mechanism. These single-crystalline nanomembrane photodetectors also exhibit unique optoelectronic properties, such as the strong field effect and spectral selectivity.
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Affiliation(s)
- Zhenyang Xia
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Haomin Song
- Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - Munho Kim
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Ming Zhou
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Tzu-Hsuan Chang
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Dong Liu
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Xin Yin
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kanglin Xiong
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Hongyi Mi
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Xudong Wang
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Fengnian Xia
- Department of Electrical Engineering, Yale University, New Haven, CT 06511, USA
| | - Zongfu Yu
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Zhenqiang (Jack) Ma
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, WI 53706, USA
| | - Qiaoqiang Gan
- Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
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720
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Bruno OP, Pérez-Arancibia C. Windowed Green function method for the Helmholtz equation in the presence of multiply layered media. Proc Math Phys Eng Sci 2017; 473:20170161. [PMID: 28690415 PMCID: PMC5493953 DOI: 10.1098/rspa.2017.0161] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/11/2017] [Indexed: 11/12/2022] Open
Abstract
This paper presents a new methodology for the solution of problems of two- and three-dimensional acoustic scattering (and, in particular, two-dimensional electromagnetic scattering) by obstacles and defects in the presence of an arbitrary number of penetrable layers. Relying on the use of certain slow-rise windowing functions, the proposed windowed Green function approach efficiently evaluates oscillatory integrals over unbounded domains, with high accuracy, without recourse to the highly expensive Sommerfeld integrals that have typically been used to account for the effect of underlying planar multilayer structures. The proposed methodology, whose theoretical basis was presented in the recent contribution (Bruno et al. 2016 SIAM J. Appl. Math.76, 1871-1898. (doi:10.1137/15M1033782)), is fast, accurate, flexible and easy to implement. Our numerical experiments demonstrate that the numerical errors resulting from the proposed approach decrease faster than any negative power of the window size. In a number of examples considered in this paper, the proposed method is up to thousands of times faster, for a given accuracy, than corresponding methods based on the use of Sommerfeld integrals.
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Affiliation(s)
- O. P. Bruno
- Computing and Mathematical Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - C. Pérez-Arancibia
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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721
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Milton RD, Minteer SD. Direct enzymatic bioelectrocatalysis: differentiating between myth and reality. J R Soc Interface 2017; 14:20170253. [PMID: 28637918 PMCID: PMC5493807 DOI: 10.1098/rsif.2017.0253] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/30/2017] [Indexed: 02/03/2023] Open
Abstract
Enzymatic bioelectrocatalysis is being increasingly exploited to better understand oxidoreductase enzymes, to develop minimalistic yet specific biosensor platforms, and to develop alternative energy conversion devices and bioelectrosynthetic devices for the production of energy and/or important chemical commodities. In some cases, these enzymes are able to electronically communicate with an appropriately designed electrode surface without the requirement of an electron mediator to shuttle electrons between the enzyme and electrode. This phenomenon has been termed direct electron transfer or direct bioelectrocatalysis. While many thorough studies have extensively investigated this fascinating feat, it is sometimes difficult to differentiate desirable enzymatic bioelectrocatalysis from electrocatalysis deriving from inactivated enzyme that may have also released its catalytic cofactor. This article will review direct bioelectrocatalysis of several oxidoreductases, with an emphasis on experiments that provide support for direct bioelectrocatalysis versus denatured enzyme or dissociated cofactor. Finally, this review will conclude with a series of proposed control experiments that could be adopted to discern successful direct electronic communication of an enzyme from its denatured counterpart.
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Affiliation(s)
- Ross D Milton
- Department of Chemistry, University of Utah, 315 S 1400 E, Room 2020, Salt Lake City, UT 84112, USA
| | - Shelley D Minteer
- Department of Chemistry, University of Utah, 315 S 1400 E, Room 2020, Salt Lake City, UT 84112, USA
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722
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Ilic O, Kaminer I, Zhen B, Miller OD, Buljan H, Soljačić M. Topologically enabled optical nanomotors. Sci Adv 2017; 3:e1602738. [PMID: 28695194 PMCID: PMC5493414 DOI: 10.1126/sciadv.1602738] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 05/10/2017] [Indexed: 05/14/2023]
Abstract
Shaping the topology of light, by way of spin or orbital angular momentum engineering, is a powerful tool to manipulate matter on the nanoscale. Conventionally, such methods focus on shaping the incident beam of light and not the full interaction between the light and the object to be manipulated. We theoretically show that tailoring the topology of the phase space of the light particle interaction is a fundamentally more versatile approach, enabling dynamics that may not be achievable by shaping of the light alone. In this manner, we find that optically asymmetric (Janus) particles can become stable nanoscale motors even in a light field with zero angular momentum. These precessing steady states arise from topologically protected anticrossing behavior of the vortices of the optical torque vector field. Furthermore, by varying the wavelength of the incident light, we can control the number, orientations, and the stability of the spinning states. These results show that the combination of phase-space topology and particle asymmetry can provide a powerful degree of freedom in designing nanoparticles for optimal external manipulation in a range of nano-optomechanical applications.
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Affiliation(s)
- Ognjen Ilic
- Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Corresponding author.
| | - Ido Kaminer
- Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Bo Zhen
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Physics Department and Solid State Institute, Technion, Haifa 32000, Israel
| | - Owen D. Miller
- Department of Applied Physics and Energy Sciences Institute, Yale University, New Haven, CT 06520, USA
| | - Hrvoje Buljan
- Department of Physics, University of Zagreb, Bijenička c. 32, 10000 Zagreb, Croatia
| | - Marin Soljačić
- Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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723
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Patel SN, Glaudell AM, Peterson KA, Thomas EM, O’Hara KA, Lim E, Chabinyc ML. Morphology controls the thermoelectric power factor of a doped semiconducting polymer. Sci Adv 2017; 3:e1700434. [PMID: 28630931 PMCID: PMC5473677 DOI: 10.1126/sciadv.1700434] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/28/2017] [Indexed: 05/15/2023]
Abstract
The electrical performance of doped semiconducting polymers is strongly governed by processing methods and underlying thin-film microstructure. We report on the influence of different doping methods (solution versus vapor) on the thermoelectric power factor (PF) of PBTTT molecularly p-doped with F n TCNQ (n = 2 or 4). The vapor-doped films have more than two orders of magnitude higher electronic conductivity (σ) relative to solution-doped films. On the basis of resonant soft x-ray scattering, vapor-doped samples are shown to have a large orientational correlation length (OCL) (that is, length scale of aligned backbones) that correlates to a high apparent charge carrier mobility (μ). The Seebeck coefficient (α) is largely independent of OCL. This reveals that, unlike σ, leveraging strategies to improve μ have a smaller impact on α. Our best-performing sample with the largest OCL, vapor-doped PBTTT:F4TCNQ thin film, has a σ of 670 S/cm and an α of 42 μV/K, which translates to a large PF of 120 μW m-1 K-2. In addition, despite the unfavorable offset for charge transfer, doping by F2TCNQ also leads to a large PF of 70 μW m-1 K-2, which reveals the potential utility of weak molecular dopants. Overall, our work introduces important general processing guidelines for the continued development of doped semiconducting polymers for thermoelectrics.
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Affiliation(s)
- Shrayesh N. Patel
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Anne M. Glaudell
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Kelly A. Peterson
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Elayne M. Thomas
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Kathryn A. O’Hara
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Eunhee Lim
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
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724
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Weigand WJ, Messmore A, Tu J, Morales-Sanz A, Blair DL, Deheyn DD, Urbach JS, Robertson-Anderson RM. Active microrheology determines scale-dependent material properties of Chaetopterus mucus. PLoS One 2017; 12:e0176732. [PMID: 28562662 PMCID: PMC5451080 DOI: 10.1371/journal.pone.0176732] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/15/2017] [Indexed: 12/24/2022] Open
Abstract
We characterize the lengthscale-dependent rheological properties of mucus from the ubiquitous Chaetopterus marine worm. We use optically trapped probes (2-10 μm) to induce microscopic strains and measure the stress response as a function of oscillation amplitude. Our results show that viscoelastic properties are highly dependent on strain scale (l), indicating three distinct lengthscale-dependent regimes at l1 ≤4 μm, l2≈4-10 μm, and l3≥10 μm. While mucus response is similar to water for l1, suggesting that probes rarely contact the mucus mesh, the response for l2 is distinctly more viscous and independent of probe size, indicative of continuum mechanics. Only for l3 does the response match the macroscopic elasticity, likely due to additional stiffer constraints that strongly resist probe displacement. Our results suggest that, rather than a single lengthscale governing crossover from viscous to elastic, mucus responds as a hierarchical network with a loose biopolymer mesh coupled to a larger scaffold responsible for macroscopic gel-like mechanics.
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Affiliation(s)
- W. J. Weigand
- Department of Physics and Biophysics, University of San Diego, San Diego, California, United States of America
| | - A. Messmore
- Department of Physics and Biophysics, University of San Diego, San Diego, California, United States of America
| | - J. Tu
- Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla, California, United States of America
| | - A. Morales-Sanz
- Department of Physics and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington DC, United States of America
| | - D. L. Blair
- Department of Physics and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington DC, United States of America
| | - D. D. Deheyn
- Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla, California, United States of America
| | - J. S. Urbach
- Department of Physics and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington DC, United States of America
| | - R. M. Robertson-Anderson
- Department of Physics and Biophysics, University of San Diego, San Diego, California, United States of America
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725
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Li Q, Luo TY, Taylor MG, Wang S, Zhu X, Song Y, Mpourmpakis G, Rosi NL, Jin R. Molecular "surgery" on a 23-gold-atom nanoparticle. Sci Adv 2017; 3:e1603193. [PMID: 28560348 PMCID: PMC5438218 DOI: 10.1126/sciadv.1603193] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/20/2017] [Indexed: 05/05/2023]
Abstract
Compared to molecular chemistry, nanochemistry is still far from being capable of tailoring particle structure and functionality at an atomic level. Numerous effective methodologies that can precisely tailor specific groups in organic molecules without altering the major carbon bones have been developed, but for nanoparticles, it is still extremely difficult to realize the atomic-level tailoring of specific sites in a particle without changing the structure of other parts (for example, replacing specific surface motifs and deleting one or two metal atoms). This issue severely limits nanochemists from knowing how different motifs in a nanoparticle contribute to its overall properties. We demonstrate a site-specific "surgery" on the surface motif of an atomically precise 23-gold-atom [Au23(SR)16]- nanoparticle by a two-step metal-exchange method, which leads to the "resection" of two surface gold atoms and the formation of a new 21-gold-atom nanoparticle, [Au21(SR)12(Ph2PCH2PPh2)2]+, without changing the other parts of the starting nanoparticle structure. This precise surgery of the nanocluster reveals the different reactivity of the surface motifs and the inner core: the least effect of surface motifs on optical absorption but a distinct effect on photoluminescence (that is, a 10-fold enhancement of luminescence after the tailoring). First-principles calculations further reveal the thermodynamically preferred reaction pathway for the formation of [Au21(SR)12(Ph2PCH2PPh2)2]+. This work constitutes a major step toward the development of atomically precise, versatile nanochemistry for the precise tailoring of the nanocluster structure to control its properties.
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Affiliation(s)
- Qi Li
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Tian-Yi Luo
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Michael G. Taylor
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Shuxin Wang
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Xiaofan Zhu
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Yongbo Song
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Giannis Mpourmpakis
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Nathaniel L. Rosi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Rongchao Jin
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Corresponding author.
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726
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Abstract
Microfluidics are widely used in research ranging from bioengineering and biomedical disciplines to chemistry and nanotechnology. As such, there are a large number of options for the devices used to drive and control flow through microfluidic channels. Commercially available syringe pumps are probably the most commonly used instruments for this purpose, but are relatively high-cost and have inherent limitations due to their flow profiles when they are run open-loop. Here, we present a low-cost ($110) syringe pressure pump that uses feedback control to regulate the pressure into microfluidic chips. Using an open-source microcontroller board (Arduino), we demonstrate an easily operated and programmable syringe pump that can be run using either a PID or bang-bang control method. Through feedback control of the pressure at the inlets of two microfluidic geometries, we have shown stability of our device to within ±1% of the set point using a PID control method and within ±5% of the set point using a bang-bang control method with response times of less than 1 second. This device offers a low-cost option to drive and control well-regulated pressure-driven flow through microfluidic chips.
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Affiliation(s)
- John R. Lake
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Keith C. Heyde
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States of America
| | - Warren C. Ruder
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
- * E-mail:
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727
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Abstract
Origami structures are of great interest in microelectronics, soft actuators, mechanical metamaterials, and biomedical devices. Current methods of fabricating origami structures still have several limitations, such as complex material systems or tedious processing steps. We present a simple approach for creating three-dimensional (3D) origami structures by the frontal photopolymerization method, which can be easily implemented by using a commercial projector. The concept of our method is based on the volume shrinkage during photopolymerization. By adding photoabsorbers into the polymer resin, an attenuated light field is created and leads to a nonuniform curing along the thickness direction. The layer directly exposed to light cures faster than the next layer; this nonuniform curing degree leads to nonuniform curing-induced volume shrinkage. This further introduces a nonuniform stress field, which drives the film to bend toward the newly formed side. The degree of bending can be controlled by adjusting the gray scale and the irradiation time, an easy approach for creating origami structures. The behavior is examined both experimentally and theoretically. Two methods are also proposed to create different types of 3D origami structures.
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Affiliation(s)
- Zeang Zhao
- College of Engineering, Peking University, Beijing 100871, P. R. China
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Jiangtao Wu
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Xiaoming Mu
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Haosen Chen
- Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - H. Jerry Qi
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Corresponding author. (H.J.Q.); or (D.F.)
| | - Daining Fang
- College of Engineering, Peking University, Beijing 100871, P. R. China
- Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing 100081, P. R. China
- Corresponding author. (H.J.Q.); or (D.F.)
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728
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Rudy SH, Brunton SL, Proctor JL, Kutz JN. Data-driven discovery of partial differential equations. Sci Adv 2017; 3:e1602614. [PMID: 28508044 PMCID: PMC5406137 DOI: 10.1126/sciadv.1602614] [Citation(s) in RCA: 209] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 02/11/2017] [Indexed: 05/18/2023]
Abstract
We propose a sparse regression method capable of discovering the governing partial differential equation(s) of a given system by time series measurements in the spatial domain. The regression framework relies on sparsity-promoting techniques to select the nonlinear and partial derivative terms of the governing equations that most accurately represent the data, bypassing a combinatorially large search through all possible candidate models. The method balances model complexity and regression accuracy by selecting a parsimonious model via Pareto analysis. Time series measurements can be made in an Eulerian framework, where the sensors are fixed spatially, or in a Lagrangian framework, where the sensors move with the dynamics. The method is computationally efficient, robust, and demonstrated to work on a variety of canonical problems spanning a number of scientific domains including Navier-Stokes, the quantum harmonic oscillator, and the diffusion equation. Moreover, the method is capable of disambiguating between potentially nonunique dynamical terms by using multiple time series taken with different initial data. Thus, for a traveling wave, the method can distinguish between a linear wave equation and the Korteweg-de Vries equation, for instance. The method provides a promising new technique for discovering governing equations and physical laws in parameterized spatiotemporal systems, where first-principles derivations are intractable.
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Affiliation(s)
- Samuel H. Rudy
- Department of Applied Mathematics, University of Washington, Seattle, WA 98195, USA
- Corresponding author.
| | - Steven L. Brunton
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Joshua L. Proctor
- Institute for Disease Modeling, 3150 139th Avenue Southeast, Bellevue, WA 98005, USA
| | - J. Nathan Kutz
- Department of Applied Mathematics, University of Washington, Seattle, WA 98195, USA
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729
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Popova E, Rodgers TM, Gong X, Cecen A, Madison JD, Kalidindi SR. Process-Structure Linkages Using a Data Science Approach: Application to Simulated Additive Manufacturing Data. Integr Mater Manuf Innov 2017; 6:54-68. [PMID: 31976205 PMCID: PMC6946012 DOI: 10.1007/s40192-017-0088-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 11/17/2016] [Indexed: 06/10/2023]
Abstract
A novel data science workflow is developed and demonstrated to extract process-structure linkages (i.e., reduced-order model) for microstructure evolution problems when the final microstructure depends on (simulation or experimental) processing parameters. This workflow consists of four main steps: data pre-processing, microstructure quantification, dimensionality reduction, and extraction/validation of process-structure linkages. Methods that can be employed within each step vary based on the type and amount of available data. In this paper, this data-driven workflow is applied to a set of synthetic additive manufacturing microstructures obtained using the Potts-kinetic Monte Carlo (kMC) approach. Additive manufacturing techniques inherently produce complex microstructures that can vary significantly with processing conditions. Using the developed workflow, a low-dimensional data-driven model was established to correlate process parameters with the predicted final microstructure. Additionally, the modular workflows developed and presented in this work facilitate easy dissemination and curation by the broader community.
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Affiliation(s)
- Evdokia Popova
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - Theron M. Rodgers
- Computational Materials & Data Science, Sandia National Laboratories, PO Box 5800, MS-1411, Albuquerque, NM 87185 USA
| | - Xinyi Gong
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - Ahmet Cecen
- School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - Jonathan D. Madison
- Material Mechanics, Sandia National Laboratories, PO Box 5800 MS-0889, Albuquerque, 87185 NM USA
| | - Surya R. Kalidindi
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
- School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
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730
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Rubino G, Rozema LA, Feix A, Araújo M, Zeuner JM, Procopio LM, Brukner Č, Walther P. Experimental verification of an indefinite causal order. Sci Adv 2017; 3:e1602589. [PMID: 28378018 PMCID: PMC5365250 DOI: 10.1126/sciadv.1602589] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 02/09/2017] [Indexed: 05/27/2023]
Abstract
Investigating the role of causal order in quantum mechanics has recently revealed that the causal relations of events may not be a priori well defined in quantum theory. Although this has triggered a growing interest on the theoretical side, creating processes without a causal order is an experimental task. We report the first decisive demonstration of a process with an indefinite causal order. To do this, we quantify how incompatible our setup is with a definite causal order by measuring a "causal witness." This mathematical object incorporates a series of measurements that are designed to yield a certain outcome only if the process under examination is not consistent with any well-defined causal order. In our experiment, we perform a measurement in a superposition of causal orders-without destroying the coherence-to acquire information both inside and outside of a "causally nonordered process." Using this information, we experimentally determine a causal witness, demonstrating by almost 7 SDs that the experimentally implemented process does not have a definite causal order.
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Affiliation(s)
- Giulia Rubino
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
| | - Lee A. Rozema
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
| | - Adrien Feix
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, Vienna A-1090, Austria
| | - Mateus Araújo
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, Vienna A-1090, Austria
| | - Jonas M. Zeuner
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
| | - Lorenzo M. Procopio
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
| | - Časlav Brukner
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, Vienna A-1090, Austria
| | - Philip Walther
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
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731
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Bruno OP, Fernandez-Lado AG. Rapidly convergent quasi-periodic Green functions for scattering by arrays of cylinders-including Wood anomalies. Proc Math Phys Eng Sci 2017; 473:20160802. [PMID: 28413346 PMCID: PMC5378244 DOI: 10.1098/rspa.2016.0802] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/27/2017] [Indexed: 11/12/2022] Open
Abstract
This paper presents a full-spectrum Green-function methodology (which is valid, in particular, at and around Wood-anomaly frequencies) for evaluation of scattering by periodic arrays of cylinders of arbitrary cross section-with application to wire gratings, particle arrays and reflectarrays and, indeed, general arrays of conducting or dielectric bounded obstacles under both transverse electric and transverse magnetic polarized illumination. The proposed method, which, for definiteness, is demonstrated here for arrays of perfectly conducting particles under transverse electric polarization, is based on the use of the shifted Green-function method introduced in a recent contribution (Bruno & Delourme 2014 J. Computat. Phys.262, 262-290 (doi:10.1016/j.jcp.2013.12.047)). A certain infinite term arises at Wood anomalies for the cylinder-array problems considered here that is not present in the previous rough-surface case. As shown in this paper, these infinite terms can be treated via an application of ideas related to the Woodbury-Sherman-Morrison formulae. The resulting approach, which is applicable to general arrays of obstacles even at and around Wood-anomaly frequencies, exhibits fast convergence and high accuracies. For example, a few hundreds of milliseconds suffice for the proposed approach to evaluate solutions throughout the resonance region (wavelengths comparable to the period and cylinder sizes) with full single-precision accuracy.
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Affiliation(s)
- Oscar P. Bruno
- Computing and Mathematical Sciences, Caltech, Pasadena, CA 91125, USA
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732
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Wang Y, Zhu C, Pfattner R, Yan H, Jin L, Chen S, Molina-Lopez F, Lissel F, Liu J, Rabiah NI, Chen Z, Chung JW, Linder C, Toney MF, Murmann B, Bao Z. A highly stretchable, transparent, and conductive polymer. Sci Adv 2017; 3:e1602076. [PMID: 28345040 PMCID: PMC5345924 DOI: 10.1126/sciadv.1602076] [Citation(s) in RCA: 484] [Impact Index Per Article: 69.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 02/16/2017] [Indexed: 05/19/2023]
Abstract
Previous breakthroughs in stretchable electronics stem from strain engineering and nanocomposite approaches. Routes toward intrinsically stretchable molecular materials remain scarce but, if successful, will enable simpler fabrication processes, such as direct printing and coating, mechanically robust devices, and more intimate contact with objects. We report a highly stretchable conducting polymer, realized with a range of enhancers that serve a dual function: (i) they change morphology and (ii) they act as conductivity-enhancing dopants in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The polymer films exhibit conductivities comparable to the best reported values for PEDOT:PSS, with over 3100 S/cm under 0% strain and over 4100 S/cm under 100% strain-among the highest for reported stretchable conductors. It is highly durable under cyclic loading, with the conductivity maintained at 3600 S/cm even after 1000 cycles to 100% strain. The conductivity remained above 100 S/cm under 600% strain, with a fracture strain of 800%, which is superior to even the best silver nanowire- or carbon nanotube-based stretchable conductor films. The combination of excellent electrical and mechanical properties allowed it to serve as interconnects for field-effect transistor arrays with a device density that is five times higher than typical lithographically patterned wavy interconnects.
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Affiliation(s)
- Yue Wang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Chenxin Zhu
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Raphael Pfattner
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Hongping Yan
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Lihua Jin
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA
| | - Shucheng Chen
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | | | - Franziska Lissel
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jia Liu
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Noelle I. Rabiah
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Zheng Chen
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jong Won Chung
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Samsung Advanced Institute of Technology, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, South Korea
| | - Christian Linder
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA
| | - Michael F. Toney
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Boris Murmann
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Corresponding author.
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733
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Willner AE, Ren Y, Xie G, Yan Y, Li L, Zhao Z, Wang J, Tur M, Molisch AF, Ashrafi S. Recent advances in high-capacity free-space optical and radio-frequency communications using orbital angular momentum multiplexing. Philos Trans A Math Phys Eng Sci 2017; 375:rsta.2015.0439. [PMID: 28069770 PMCID: PMC5247483 DOI: 10.1098/rsta.2015.0439] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/13/2016] [Indexed: 05/20/2023]
Abstract
There is a continuing growth in the demand for data bandwidth, and the multiplexing of multiple independent data streams has the potential to provide the needed data capacity. One technique uses the spatial domain of an electromagnetic (EM) wave, and space division multiplexing (SDM) has become increasingly important for increased transmission capacity and spectral efficiency of a communication system. A subset of SDM is mode division multiplexing (MDM), in which multiple orthogonal beams each on a different mode can be multiplexed. A potential modal basis set to achieve MDM is to use orbital angular momentum (OAM) of EM waves. In such a system, multiple OAM beams each carrying an independent data stream are multiplexed at the transmitter, propagate through a common medium and are demultiplexed at the receiver. As a result, the total capacity and spectral efficiency of the communication system can be multiplied by a factor equal to the number of transmitted OAM modes. Over the past few years, progress has been made in understanding the advantages and limitations of using multiplexed OAM beams for communication systems. In this review paper, we highlight recent advances in the use of OAM multiplexing for high-capacity free-space optical and millimetre-wave communications. We discuss different technical challenges (e.g. atmospheric turbulence and crosstalk) as well as potential techniques to mitigate such degrading effects.This article is part of the themed issue 'Optical orbital angular momentum'.
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Affiliation(s)
- Alan E Willner
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Yongxiong Ren
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Guodong Xie
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Yan Yan
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Long Li
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Zhe Zhao
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Jian Wang
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, People's Republic of China
| | - Moshe Tur
- School of Electrical Engineering, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Andreas F Molisch
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
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734
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Kunert JM, Proctor JL, Brunton SL, Kutz JN. Spatiotemporal Feedback and Network Structure Drive and Encode Caenorhabditis elegans Locomotion. PLoS Comput Biol 2017; 13:e1005303. [PMID: 28076347 PMCID: PMC5226684 DOI: 10.1371/journal.pcbi.1005303] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 12/12/2016] [Indexed: 01/19/2023] Open
Abstract
Using a computational model of the Caenorhabditis elegans connectome dynamics, we show that proprioceptive feedback is necessary for sustained dynamic responses to external input. This is consistent with the lack of biophysical evidence for a central pattern generator, and recent experimental evidence that proprioception drives locomotion. The low-dimensional functional response of the Caenorhabditis elegans network of neurons to proprioception-like feedback is optimized by input of specific spatial wavelengths which correspond to the spatial scale of real body shape dynamics. Furthermore, we find that the motor subcircuit of the network is responsible for regulating this response, in agreement with experimental expectations. To explore how the connectomic dynamics produces the observed two-mode, oscillatory limit cycle behavior from a static fixed point, we probe the fixed point's low-dimensional structure using Dynamic Mode Decomposition. This reveals that the nonlinear network dynamics encode six clusters of dynamic modes, with timescales spanning three orders of magnitude. Two of these six dynamic mode clusters correspond to previously-discovered behavioral modes related to locomotion. These dynamic modes and their timescales are encoded by the network's degree distribution and specific connectivity. This suggests that behavioral dynamics are partially encoded within the connectome itself, the connectivity of which facilitates proprioceptive control.
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Affiliation(s)
- James M. Kunert
- Department of Physics, University of Washington, Seattle, Washington, United States of America
| | - Joshua L. Proctor
- Institute for Disease Modeling, Bellevue, Washington, United States of America
| | - Steven L. Brunton
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
| | - J. Nathan Kutz
- Department of Applied Mathematics, University of Washington, Seattle, Washington, United States of America
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735
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Abstract
Multi-spectral imagery can enhance decision-making by supplying multiple complementary sources of information. However, overloading an observer with information can deter decision-making. Hence, it is critical to assess multi-spectral image displays using human performance. Accuracy and response times (RTs) are fundamental for assessment, although without sophisticated empirical designs, they offer little information about why performance is better or worse. Systems factorial technology (SFT) is a framework for study design and analysis that examines observers' processing mechanisms, not just overall performance. In the current work, we use SFT to compare a display with two sensor images alongside each another with a display in which there is a single composite image. In our first experiment, the SFT results indicated that both display approaches suffered from limited workload capacity and more so for the composite imagery. In the second experiment, we examined the change in observer performance over the course of multiple days of practice. Participants' accuracy and RTs improved with training, but their capacity limitations were unaffected. Using SFT, we found that the capacity limitation was not due to an inefficient serial examination of the imagery by the participants. There are two clear implications of these results: Observers are less efficient with multi-spectral images than single images and the side-by-side display of source images is a viable alternative to composite imagery. SFT was necessary for these conclusions because it provided an appropriate mechanism for comparing single-source images to multi-spectral images and because it ruled out serial processing as the source of the capacity limitation.
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Affiliation(s)
- Elizabeth L. Fox
- Department of Psychology, Wright State University, Dayton, 45435 OH USA
| | - Joseph W. Houpt
- Department of Psychology, Wright State University, Dayton, 45435 OH USA
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736
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Sherman VR, Yaraghi NA, Kisailus D, Meyers MA. Microstructural and geometric influences in the protective scales of Atractosteus spatula. J R Soc Interface 2016; 13:20160595. [PMID: 27974575 PMCID: PMC5221522 DOI: 10.1098/rsif.2016.0595] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 11/17/2016] [Indexed: 11/12/2022] Open
Abstract
Atractosteus spatula has been described as a living fossil (having existed for 100 Myr), retaining morphological characteristics of early ancestors such as the ability to breathe air and survive above water for hours. Its highly effective armour consists of ganoid scales. We analyse the protective function of the scales and identify key features which lead to their resistance to failure. Microstructural features include: a twisted cross-plied mineral arrangement that inhibits crack propagation in the external ganoine layer, mineral crystals that deflect cracks in the bony region in order to activate the strength of mineralized collagen fibrils, and saw-tooth ridges along the interface between the two scale layers which direct cracks away from the intrinsically weak interface. The macroscale geometry is additionally evaluated and it is shown that the scales retain full coverage in spite of minimal overlap between adjacent scales while conforming to physiologically required strain and maintaining flexibility via a process in which adjacent rows of scales slide and concurrently reorient.
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Affiliation(s)
- Vincent R Sherman
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA
| | - Nicholas A Yaraghi
- Materials Science and Engineering Program, University of California, Riverside, Riverside, CA, USA
| | - David Kisailus
- Materials Science and Engineering Program, University of California, Riverside, Riverside, CA, USA
| | - Marc A Meyers
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA
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737
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Zimmerman JF, Parameswaran R, Murray G, Wang Y, Burke M, Tian B. Cellular uptake and dynamics of unlabeled freestanding silicon nanowires. Sci Adv 2016; 2:e1601039. [PMID: 28028534 PMCID: PMC5161427 DOI: 10.1126/sciadv.1601039] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 11/08/2016] [Indexed: 05/12/2023]
Abstract
The ability to seamlessly merge electronic devices with biological systems at the cellular length scale is an exciting prospect for exploring new fundamental cell biology and in designing next-generation therapeutic devices. Semiconductor nanowires are well suited for achieving this goal because of their intrinsic size and wide range of possible configurations. However, current studies have focused primarily on delivering substrate-bound nanowire devices through mechanical abrasion or electroporation, with these bulkier substrates negating many of the inherent benefits of using nanoscale materials. To improve on this, an important next step is learning how to distribute these devices in a drug-like fashion, where cells can naturally uptake and incorporate these electronic components, allowing for truly noninvasive device integration. We show that silicon nanowires (SiNWs) can potentially be used as such a system, demonstrating that label-free SiNWs can be internalized in multiple cell lines (96% uptake rate), undergoing an active "burst-like" transport process. Our results show that, rather than through exogenous manipulation, SiNWs are internalized primarily through an endogenous phagocytosis pathway, allowing cellular integration of these materials. To study this behavior, we have developed a robust set of methodologies for quantitatively examining high-aspect ratio nanowire-cell interactions in a time-dependent manner on both single-cell and ensemble levels. This approach represents one of the first dynamic studies of semiconductor nanowire internalization and offers valuable insight into designing devices for biomolecule delivery, intracellular sensing, and photoresponsive therapies.
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Affiliation(s)
- John F. Zimmerman
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Ramya Parameswaran
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Graeme Murray
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Yucai Wang
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
- The CAS Key Laboratory of Innate Immunity and Chronic Diseases, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, PR China
| | - Michael Burke
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Bozhi Tian
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
- Corresponding author.
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738
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Carpenter KLH, Sprechmann P, Calderbank R, Sapiro G, Egger HL. Quantifying Risk for Anxiety Disorders in Preschool Children: A Machine Learning Approach. PLoS One 2016; 11:e0165524. [PMID: 27880812 PMCID: PMC5120781 DOI: 10.1371/journal.pone.0165524] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 10/13/2016] [Indexed: 11/18/2022] Open
Abstract
Early childhood anxiety disorders are common, impairing, and predictive of anxiety and mood disorders later in childhood. Epidemiological studies over the last decade find that the prevalence of impairing anxiety disorders in preschool children ranges from 0.3% to 6.5%. Yet, less than 15% of young children with an impairing anxiety disorder receive a mental health evaluation or treatment. One possible reason for the low rate of care for anxious preschoolers is the lack of affordable, timely, reliable and valid tools for identifying young children with clinically significant anxiety. Diagnostic interviews assessing psychopathology in young children require intensive training, take hours to administer and code, and are not available for use outside of research settings. The Preschool Age Psychiatric Assessment (PAPA) is a reliable and valid structured diagnostic parent-report interview for assessing psychopathology, including anxiety disorders, in 2 to 5 year old children. In this paper, we apply machine-learning tools to already collected PAPA data from two large community studies to identify sub-sets of PAPA items that could be developed into an efficient, reliable, and valid screening tool to assess a young child's risk for an anxiety disorder. Using machine learning, we were able to decrease by an order of magnitude the number of items needed to identify a child who is at risk for an anxiety disorder with an accuracy of over 96% for both generalized anxiety disorder (GAD) and separation anxiety disorder (SAD). Additionally, rather than considering GAD or SAD as discrete/binary entities, we present a continuous risk score representing the child's risk of meeting criteria for GAD or SAD. Identification of a short question-set that assesses risk for an anxiety disorder could be a first step toward development and validation of a relatively short screening tool feasible for use in pediatric clinics and daycare/preschool settings.
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Affiliation(s)
- Kimberly L. H. Carpenter
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, North Carolina, United States of America
- * E-mail:
| | - Pablo Sprechmann
- Electrical and Computer Engineering, Biomedical Engineering, and Computer Science, Duke University, Durham, North Carolina, United States of America
| | - Robert Calderbank
- Electrical and Computer Engineering, Biomedical Engineering, and Computer Science, Duke University, Durham, North Carolina, United States of America
| | - Guillermo Sapiro
- Electrical and Computer Engineering, Biomedical Engineering, and Computer Science, Duke University, Durham, North Carolina, United States of America
| | - Helen L. Egger
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, North Carolina, United States of America
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739
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Conn BE, Atnagulov A, Yoon B, Barnett RN, Landman U, Bigioni TP. Confirmation of a de novo structure prediction for an atomically precise monolayer-coated silver nanoparticle. Sci Adv 2016; 2:e1601609. [PMID: 28138537 PMCID: PMC5262450 DOI: 10.1126/sciadv.1601609] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/25/2016] [Indexed: 05/05/2023]
Abstract
Fathoming the principles underpinning the structures of monolayer-coated molecular metal nanoparticles remains an enduring challenge. Notwithstanding recent x-ray determinations, coveted veritable de novo structural predictions are scarce. Building on recent syntheses and de novo structure predictions of M3Au x Ag17-x (TBBT)12, where M is a countercation, x = 0 or 1, and TBBT is 4-tert-butylbenzenethiol, we report an x-ray-determined structure that authenticates an a priori prediction and, in conjunction with first-principles theoretical analysis, lends force to the underlying forecasting methodology. The predicted and verified Ag(SR)3 monomer, together with the recently discovered Ag2(SR)5 dimer and Ag3(SR)6 trimer, establishes a family of unique mount motifs for silver thiolate nanoparticles, expanding knowledge beyond the earlier-known Au-S staples in thiol-capped gold nanoclusters. These findings demonstrate key principles underlying ligand-shell anchoring to the metal core, as well as unique T-like benzene dimer and cyclic benzene trimer ligand bundling configurations, opening vistas for rational design of metal and alloy nanoparticles.
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Affiliation(s)
- Brian E. Conn
- Department of Chemistry, University of Toledo, Toledo, OH 43606, USA
| | - Aydar Atnagulov
- Department of Chemistry, University of Toledo, Toledo, OH 43606, USA
| | - Bokwon Yoon
- School of Solar and Advanced Renewable Energy, University of Toledo, Toledo, OH 43606, USA
| | - Robert N. Barnett
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332–0430, USA
| | - Uzi Landman
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332–0430, USA
- Corresponding author. (U.L.); (T.P.B.)
| | - Terry P. Bigioni
- Department of Chemistry, University of Toledo, Toledo, OH 43606, USA
- School of Solar and Advanced Renewable Energy, University of Toledo, Toledo, OH 43606, USA
- Corresponding author. (U.L.); (T.P.B.)
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740
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Yeh YT, Tang Y, Sebastian A, Dasgupta A, Perea-Lopez N, Albert I, Lu H, Terrones M, Zheng SY. Tunable and label-free virus enrichment for ultrasensitive virus detection using carbon nanotube arrays. Sci Adv 2016; 2:e1601026. [PMID: 27730213 PMCID: PMC5055386 DOI: 10.1126/sciadv.1601026] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 08/31/2016] [Indexed: 05/13/2023]
Abstract
Viral infectious diseases can erupt unpredictably, spread rapidly, and ravage mass populations. Although established methods, such as polymerase chain reaction, virus isolation, and next-generation sequencing have been used to detect viruses, field samples with low virus count pose major challenges in virus surveillance and discovery. We report a unique carbon nanotube size-tunable enrichment microdevice (CNT-STEM) that efficiently enriches and concentrates viruses collected from field samples. The channel sidewall in the microdevice was made by growing arrays of vertically aligned nitrogen-doped multiwalled CNTs, where the intertubular distance between CNTs could be engineered in the range of 17 to 325 nm to accurately match the size of different viruses. The CNT-STEM significantly improves detection limits and virus isolation rates by at least 100 times. Using this device, we successfully identified an emerging avian influenza virus strain [A/duck/PA/02099/2012(H11N9)] and a novel virus strain (IBDV/turkey/PA/00924/14). Our unique method demonstrates the early detection of emerging viruses and the discovery of new viruses directly from field samples, thus creating a universal platform for effectively remediating viral infectious diseases.
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Affiliation(s)
- Yin-Ting Yeh
- Micro and Nano Integrated Biosystem Laboratory, Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA
- Penn State Material Research Institute, Pennsylvania State University, University Park, PA 16802, USA
| | - Yi Tang
- Department of Veterinary and Biomedical Science, Pennsylvania State University, University Park, PA 16802, USA
| | - Aswathy Sebastian
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Archi Dasgupta
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Nestor Perea-Lopez
- Department of Physics and Center for 2-Dimensional and Layered Materials, Pennsylvania State University, University Park, PA 16802, USA
| | - Istvan Albert
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Huaguang Lu
- Department of Veterinary and Biomedical Science, Pennsylvania State University, University Park, PA 16802, USA
| | - Mauricio Terrones
- Penn State Material Research Institute, Pennsylvania State University, University Park, PA 16802, USA
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
- Department of Physics and Center for 2-Dimensional and Layered Materials, Pennsylvania State University, University Park, PA 16802, USA
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802, USA
- Corresponding author. (M.T.); (S.-Y.Z.)
| | - Si-Yang Zheng
- Micro and Nano Integrated Biosystem Laboratory, Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA
- Penn State Material Research Institute, Pennsylvania State University, University Park, PA 16802, USA
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
- Department of Electrical Engineering, Pennsylvania State University, University Park, PA 16802, USA
- Corresponding author. (M.T.); (S.-Y.Z.)
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741
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Galloway KS, Justh EW, Krishnaprasad PS. Symmetry and reduction in collectives: low-dimensional cyclic pursuit. Proc Math Phys Eng Sci 2016; 472:20160465. [PMID: 27843405 PMCID: PMC5095446 DOI: 10.1098/rspa.2016.0465] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 09/26/2016] [Indexed: 11/12/2022] Open
Abstract
We investigate low-dimensional examples of cyclic pursuit in a collective, wherein each agent employs a constant bearing (CB) steering law relative to exactly one other agent. For the case of three agents in the plane, we characterize relative equilibria and pure shape equilibria of associated closed-loop dynamics. Re-scaling time yields a reduction of phase space to two dimensions and effective tools for stability analysis. Study of bifurcation of a family of collinear equilibria dependent on a single CB control parameter reveals the presence of a rich collection of trajectories that are periodic in shape and undergo precession in physical space. For collectives in three dimensions, with an appropriate notion of CB pursuit strategy and corresponding steering law, the two-agent case proves to be explicitly integrable. These results suggest control schemes for small teams of mobile robotic agents engaged in area coverage tasks such as search and rescue, and raise interesting possibilities for behaviour in biological contexts.
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Affiliation(s)
- Kevin S. Galloway
- Department of Electrical and Computer Engineering, US Naval Academy, Annapolis, MD 21402, USA
| | - Eric W. Justh
- Naval Research Laboratory, Washington, DC 20375, USA
| | - P. S. Krishnaprasad
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, USA
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742
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Liberal I, Engheta N. Nonradiating and radiating modes excited by quantum emitters in open epsilon-near-zero cavities. Sci Adv 2016; 2:e1600987. [PMID: 27819047 PMCID: PMC5088639 DOI: 10.1126/sciadv.1600987] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 09/19/2016] [Indexed: 05/26/2023]
Abstract
Controlling the emission and interaction properties of quantum emitters (QEs) embedded within an optical cavity is a key technique in engineering light-matter interactions at the nanoscale, as well as in the development of quantum information processing. State-of-the-art optical cavities are based on high quality factor photonic crystals and dielectric resonators. However, wealthier responses might be attainable with cavities carved in more exotic materials. We theoretically investigate the emission and interaction properties of QEs embedded in open epsilon-near-zero (ENZ) cavities. Using analytical methods and numerical simulations, we demonstrate that open ENZ cavities present the unique property of supporting nonradiating modes independently of the geometry of the external boundary of the cavity (shape, size, topology, etc.). Moreover, the possibility of switching between radiating and nonradiating modes enables a dynamic control of the emission by, and the interaction between, QEs. These phenomena provide unprecedented degrees of freedom in controlling and trapping fields within optical cavities, as well as in the design of cavity opto- and acoustomechanical systems.
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743
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Buskohl PR, Vaia RA. Belousov-Zhabotinsky autonomic hydrogel composites: Regulating waves via asymmetry. Sci Adv 2016; 2:e1600813. [PMID: 27679818 PMCID: PMC5035124 DOI: 10.1126/sciadv.1600813] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/16/2016] [Indexed: 05/24/2023]
Abstract
Belousov-Zhabotinsky (BZ) autonomic hydrogel composites contain active nodes of immobilized catalyst (Ru) encased within a nonactive matrix. Designing functional hierarchies of chemical and mechanical communication between these nodes enables applications ranging from encryption, sensors, and mechanochemical actuators to artificial skin. However, robust design rules and verification of computational models are challenged by insufficient understanding of the relative importance of local (molecular) heterogeneities, active node shape, and embedment geometry on transient and steady-state behavior. We demonstrate the predominance of asymmetric embedment and node shape in low-strain, BZ-gelatin composites and correlate behavior with gradients in BZ reactants. Asymmetric embedment of square and rectangular nodes results in directional steady-state waves that initiate at the embedded edge and propagate toward the free edge. In contrast, symmetric embedment does not produce preferential wave propagation because of a lack of diffusion gradient across the catalyzed region. The initiation at the embedded edge is correlated with bromide absorption by the inactive matrix, which locally elevates the bromate concentration required for catalyst oxidation. The competition between embedment asymmetry and node geometry was used to demonstrate a repeatable switch in wave direction that functions as a signal delay. Furthermore, signal propagation in or out of the composite was demonstrated via embedment asymmetry and relative dimensions of a T-shaped active network node. Overall, structural asymmetry provides a robust approach to controlling initiation and orientation of chemical-mechanical communication within composite BZ gels.
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Affiliation(s)
- Philip R. Buskohl
- Functional Materials Division, Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, OH 45433, USA
| | - Richard A. Vaia
- Functional Materials Division, Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, OH 45433, USA
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744
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He L, Li H, Li M. Optomechanical measurement of photon spin angular momentum and optical torque in integrated photonic devices. Sci Adv 2016; 2:e1600485. [PMID: 27626072 PMCID: PMC5017824 DOI: 10.1126/sciadv.1600485] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 08/04/2016] [Indexed: 05/14/2023]
Abstract
Photons carry linear momentum and spin angular momentum when circularly or elliptically polarized. During light-matter interaction, transfer of linear momentum leads to optical forces, whereas transfer of angular momentum induces optical torque. Optical forces including radiation pressure and gradient forces have long been used in optical tweezers and laser cooling. In nanophotonic devices, optical forces can be significantly enhanced, leading to unprecedented optomechanical effects in both classical and quantum regimes. In contrast, to date, the angular momentum of light and the optical torque effect have only been used in optical tweezers but remain unexplored in integrated photonics. We demonstrate the measurement of the spin angular momentum of photons propagating in a birefringent waveguide and the use of optical torque to actuate rotational motion of an optomechanical device. We show that the sign and magnitude of the optical torque are determined by the photon polarization states that are synthesized on the chip. Our study reveals the mechanical effect of photon's polarization degree of freedom and demonstrates its control in integrated photonic devices. Exploiting optical torque and optomechanical interaction with photon angular momentum can lead to torsional cavity optomechanics and optomechanical photon spin-orbit coupling, as well as applications such as optomechanical gyroscopes and torsional magnetometry.
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745
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Giacomelli MG, Husvogt L, Vardeh H, Faulkner-Jones BE, Hornegger J, Connolly JL, Fujimoto JG. Virtual Hematoxylin and Eosin Transillumination Microscopy Using Epi-Fluorescence Imaging. PLoS One 2016; 11:e0159337. [PMID: 27500636 PMCID: PMC4976978 DOI: 10.1371/journal.pone.0159337] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 06/30/2016] [Indexed: 01/05/2023] Open
Abstract
We derive a physically realistic model for the generation of virtual transillumination, white light microscopy images using epi-fluorescence measurements from thick, unsectioned tissue. We demonstrate this technique by generating virtual transillumination H&E images of unsectioned human breast tissue from epi-fluorescence multiphoton microscopy data. The virtual transillumination algorithm is shown to enable improved contrast and color accuracy compared with previous color mapping methods. Finally, we present an open source implementation of the algorithm in OpenGL, enabling real-time GPU-based generation of virtual transillumination microscopy images using conventional fluorescence microscopy systems.
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Affiliation(s)
- Michael G. Giacomelli
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, United States of America
| | - Lennart Husvogt
- Pattern Recognition Lab, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen-Nürnberg, Germany
| | - Hilde Vardeh
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Beverly E. Faulkner-Jones
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Joachim Hornegger
- Graduate School in Advanced Optical Technologies, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen-Nürnberg, Germany
| | - James L. Connolly
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - James G. Fujimoto
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, United States of America
- * E-mail:
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746
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Chen S, Wirthmueller L, Stauber J, Lory N, Holtkotte X, Leson L, Schenkel C, Ahmad M, Hoecker U. The functional divergence between SPA1 and SPA2 in Arabidopsis photomorphogenesis maps primarily to the respective N-terminal kinase-like domain. BMC Plant Biol 2016; 16:165. [PMID: 27444995 PMCID: PMC4957354 DOI: 10.1186/s12870-016-0854-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/14/2016] [Indexed: 05/23/2023]
Abstract
BACKGROUND Plants have evolved complex mechanisms to adapt growth and development to the light environment. The COP1/SPA complex is a key repressor of photomorphogenesis in dark-grown Arabidopsis plants and acts as an E3 ubiquitin ligase to ubiquitinate transcription factors involved in the light response. In the light, COP1/SPA activity is inhibited by photoreceptors, thereby allowing accumulation of these transcription factors and a subsequent light response. Previous results have shown that the four members of the SPA family exhibit partially divergent functions. In particular, SPA1 and SPA2 strongly differ in their responsiveness to light, while they have indistinguishable activities in darkness. The much higher light-responsiveness of SPA2 is partially explained by the much stronger light-induced degradation of SPA2 when compared to SPA1. Here, we have conducted SPA1/SPA2 domain swap experiments to identify the protein domain(s) responsible for the functional divergence between SPA1 and SPA2. RESULTS We have individually swapped the three domains between SPA1 and SPA2 - the N-terminal kinase-like domain, the coiled-coil domain and the WD-repeat domain - and expressed them in spa mutant Arabidopsis plants. The phenotypes of transgenic seedlings show that the respective N-terminal kinase-like domain is primarily responsible for the respective light-responsiveness of SPA1 and SPA2. Furthermore, the most divergent part of the N-terminal domain was sufficient to confer a SPA1- or SPA2-like activity to the respective SPA protein. The stronger light-induced degradation of SPA2 when compared to SPA1 was also primarily conferred by the SPA2 N-terminal domain. At last, the different affinities of SPA1 and SPA2 for cryptochrome 2 are defined by the N-terminal domain of the respective SPA protein. In contrast, both SPA1 and SPA2 similarly interacted with COP1 in light-grown seedlings. CONCLUSIONS Our results show that the distinct activities and protein stabilities of SPA1 and SPA2 in light-grown seedlings are primarily encoded by their N-terminal kinase-like domains. Similarly, the different affinities of SPA1 and SPA2 for cry2 are explained by their respective N-terminal domain. Hence, after a duplication event during evolution, the N-terminal domains of SPA1 and SPA2 underwent subfunctionalization, possibly to allow optimal adaptation of growth and development to a changing light environment.
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Affiliation(s)
- Song Chen
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
- />Present Address: Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, 1211 Geneva 4, Switzerland
| | - Lennart Wirthmueller
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
- />Present Address: Department of Plant Biochemistry, Dahlem Center of Plant Sciences, Freie Universität Berlin, Königin-Luise-Str. 12-16, Berlin, Germany
| | - Johannes Stauber
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
| | - Niels Lory
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
| | - Xu Holtkotte
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
| | - Lisa Leson
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
| | - Christian Schenkel
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
| | - Margaret Ahmad
- />UMR 8256 (B2A) CNRS - UPMC, IBPS, Université Pierre et Marie Curie, Bat C, 9 quai Saint-Bernard, 75252 Paris Cedex 05, France
| | - Ute Hoecker
- />Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
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747
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Horvát S, Gămănuț R, Ercsey-Ravasz M, Magrou L, Gămănuț B, Van Essen DC, Burkhalter A, Knoblauch K, Toroczkai Z, Kennedy H. Spatial Embedding and Wiring Cost Constrain the Functional Layout of the Cortical Network of Rodents and Primates. PLoS Biol 2016; 14:e1002512. [PMID: 27441598 PMCID: PMC4956175 DOI: 10.1371/journal.pbio.1002512] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/14/2016] [Indexed: 01/03/2023] Open
Abstract
Mammals show a wide range of brain sizes, reflecting adaptation to diverse habitats. Comparing interareal cortical networks across brains of different sizes and mammalian orders provides robust information on evolutionarily preserved features and species-specific processing modalities. However, these networks are spatially embedded, directed, and weighted, making comparisons challenging. Using tract tracing data from macaque and mouse, we show the existence of a general organizational principle based on an exponential distance rule (EDR) and cortical geometry, enabling network comparisons within the same model framework. These comparisons reveal the existence of network invariants between mouse and macaque, exemplified in graph motif profiles and connection similarity indices, but also significant differences, such as fractionally smaller and much weaker long-distance connections in the macaque than in mouse. The latter lends credence to the prediction that long-distance cortico-cortical connections could be very weak in the much-expanded human cortex, implying an increased susceptibility to disconnection syndromes such as Alzheimer disease and schizophrenia. Finally, our data from tracer experiments involving only gray matter connections in the primary visual areas of both species show that an EDR holds at local scales as well (within 1.5 mm), supporting the hypothesis that it is a universally valid property across all scales and, possibly, across the mammalian class.
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Affiliation(s)
- Szabolcs Horvát
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem-cell and Brain Research Institute U1208, Bron, France
| | - Răzvan Gămănuț
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem-cell and Brain Research Institute U1208, Bron, France
| | - Mária Ercsey-Ravasz
- Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, Romania
- Romanian Institute of Science and Technology, Cluj-Napoca, Romania
- * E-mail: (MER); (ZT); (HK)
| | - Loïc Magrou
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem-cell and Brain Research Institute U1208, Bron, France
| | - Bianca Gămănuț
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem-cell and Brain Research Institute U1208, Bron, France
| | - David C. Van Essen
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Andreas Burkhalter
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kenneth Knoblauch
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem-cell and Brain Research Institute U1208, Bron, France
| | - Zoltán Toroczkai
- Department of Physics, and the Interdisciplinary Center for Network Science and Applications, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail: (MER); (ZT); (HK)
| | - Henry Kennedy
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem-cell and Brain Research Institute U1208, Bron, France
- * E-mail: (MER); (ZT); (HK)
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748
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Toomey MB, Lind O, Frederiksen R, Curley RW, Riedl KM, Wilby D, Schwartz SJ, Witt CC, Harrison EH, Roberts NW, Vorobyev M, McGraw KJ, Cornwall MC, Kelber A, Corbo JC. Complementary shifts in photoreceptor spectral tuning unlock the full adaptive potential of ultraviolet vision in birds. eLife 2016; 5:e15675. [PMID: 27402384 PMCID: PMC4947394 DOI: 10.7554/elife.15675] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 06/13/2016] [Indexed: 01/01/2023] Open
Abstract
Color vision in birds is mediated by four types of cone photoreceptors whose maximal sensitivities (λmax) are evenly spaced across the light spectrum. In the course of avian evolution, the λmax of the most shortwave-sensitive cone, SWS1, has switched between violet (λmax > 400 nm) and ultraviolet (λmax < 380 nm) multiple times. This shift of the SWS1 opsin is accompanied by a corresponding short-wavelength shift in the spectrally adjacent SWS2 cone. Here, we show that SWS2 cone spectral tuning is mediated by modulating the ratio of two apocarotenoids, galloxanthin and 11’,12’-dihydrogalloxanthin, which act as intracellular spectral filters in this cell type. We propose an enzymatic pathway that mediates the differential production of these apocarotenoids in the avian retina, and we use color vision modeling to demonstrate how correlated evolution of spectral tuning is necessary to achieve even sampling of the light spectrum and thereby maintain near-optimal color discrimination.
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Affiliation(s)
- Matthew B Toomey
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Olle Lind
- Department of Philosophy, Lund University, Lund, Sweden
| | - Rikard Frederiksen
- Department of Physiology and Biophysics, Boston University, Boston, United States
| | - Robert W Curley
- College of Pharmacy, The Ohio State University, Columbus, United States
| | - Ken M Riedl
- Department of Food Science and Technology, The Ohio State University, Columbus, United States
- Nutrient and Phytochemical Shared Resource of the OSU-Comprehensive Cancer Center, Columbus, United States
| | - David Wilby
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Steven J Schwartz
- Department of Food Science and Technology, The Ohio State University, Columbus, United States
| | - Christopher C Witt
- Department of Biology, University of New Mexico, Albuquerque, United States
- Museum of Southwestern Biology, University of New Mexico, Albuquerque, United States
| | - Earl H Harrison
- Department of Human Nutrition, The Ohio State University, Columbus, United States
| | - Nicholas W Roberts
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Misha Vorobyev
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - Kevin J McGraw
- School of Life Sciences, Arizona State University, Tempe, United States
| | - M Carter Cornwall
- Department of Physiology and Biophysics, Boston University, Boston, United States
| | - Almut Kelber
- Department of Biology, Lund University, Lund, Sweden
| | - Joseph C Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
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749
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Clayton KK, Swaminathan J, Yazdanbakhsh A, Zuk J, Patel AD, Kidd G. Executive Function, Visual Attention and the Cocktail Party Problem in Musicians and Non-Musicians. PLoS One 2016; 11:e0157638. [PMID: 27384330 PMCID: PMC4934907 DOI: 10.1371/journal.pone.0157638] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 06/02/2016] [Indexed: 11/24/2022] Open
Abstract
The goal of this study was to investigate how cognitive factors influence performance in a multi-talker, “cocktail-party” like environment in musicians and non-musicians. This was achieved by relating performance in a spatial hearing task to cognitive processing abilities assessed using measures of executive function (EF) and visual attention in musicians and non-musicians. For the spatial hearing task, a speech target was presented simultaneously with two intelligible speech maskers that were either colocated with the target (0° azimuth) or were symmetrically separated from the target in azimuth (at ±15°). EF assessment included measures of cognitive flexibility, inhibition control and auditory working memory. Selective attention was assessed in the visual domain using a multiple object tracking task (MOT). For the MOT task, the observers were required to track target dots (n = 1,2,3,4,5) in the presence of interfering distractor dots. Musicians performed significantly better than non-musicians in the spatial hearing task. For the EF measures, musicians showed better performance on measures of auditory working memory compared to non-musicians. Furthermore, across all individuals, a significant correlation was observed between performance on the spatial hearing task and measures of auditory working memory. This result suggests that individual differences in performance in a cocktail party-like environment may depend in part on cognitive factors such as auditory working memory. Performance in the MOT task did not differ between groups. However, across all individuals, a significant correlation was found between performance in the MOT and spatial hearing tasks. A stepwise multiple regression analysis revealed that musicianship and performance on the MOT task significantly predicted performance on the spatial hearing task. Overall, these findings confirm the relationship between musicianship and cognitive factors including domain-general selective attention and working memory in solving the “cocktail party problem”.
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Affiliation(s)
- Kameron K. Clayton
- Department of Speech, Language and Hearing Sciences, Boston University, Boston, MA, United States of America
| | - Jayaganesh Swaminathan
- Department of Speech, Language and Hearing Sciences, Boston University, Boston, MA, United States of America
- * E-mail:
| | - Arash Yazdanbakhsh
- Department for Psychological and Brain Sciences, Boston University, Boston, MA, United States of America
- Center for Computational Neuroscience and Neural Technology (CompNet), Boston University, Boston, MA, United States of America
| | - Jennifer Zuk
- Harvard Medical School, Harvard University, Boston, MA, United States of America
| | - Aniruddh D. Patel
- Department of Psychology, Tufts University, Medford, MA, United States of America
| | - Gerald Kidd
- Department of Speech, Language and Hearing Sciences, Boston University, Boston, MA, United States of America
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750
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Feng S, dos Santos MC, Carvalho BR, Lv R, Li Q, Fujisawa K, Elías AL, Lei Y, Perea-López N, Endo M, Pan M, Pimenta MA, Terrones M. Ultrasensitive molecular sensor using N-doped graphene through enhanced Raman scattering. Sci Adv 2016; 2:e1600322. [PMID: 27532043 PMCID: PMC4985229 DOI: 10.1126/sciadv.1600322] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 06/23/2016] [Indexed: 05/23/2023]
Abstract
As a novel and efficient surface analysis technique, graphene-enhanced Raman scattering (GERS) has attracted increasing research attention in recent years. In particular, chemically doped graphene exhibits improved GERS effects when compared with pristine graphene for certain dyes, and it can be used to efficiently detect trace amounts of molecules. However, the GERS mechanism remains an open question. We present a comprehensive study on the GERS effect of pristine graphene and nitrogen-doped graphene. By controlling nitrogen doping, the Fermi level (E F) of graphene shifts, and if this shift aligns with the lowest unoccupied molecular orbital (LUMO) of a molecule, charge transfer is enhanced, thus significantly amplifying the molecule's vibrational Raman modes. We confirmed these findings using different organic fluorescent molecules: rhodamine B, crystal violet, and methylene blue. The Raman signals from these dye molecules can be detected even for concentrations as low as 10(-11) M, thus providing outstanding molecular sensing capabilities. To explain our results, these nitrogen-doped graphene-molecule systems were modeled using dispersion-corrected density functional theory. Furthermore, we demonstrated that it is possible to determine the gaps between the highest occupied and the lowest unoccupied molecular orbitals (HOMO-LUMO) of different molecules when different laser excitations are used. Our simulated Raman spectra of the molecules also suggest that the measured Raman shifts come from the dyes that have an extra electron. This work demonstrates that nitrogen-doped graphene has enormous potential as a substrate when detecting low concentrations of molecules and could also allow for an effective identification of their HOMO-LUMO gaps.
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Affiliation(s)
- Simin Feng
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
| | | | - Bruno R. Carvalho
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil
| | - Ruitao Lv
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China
| | - Qing Li
- Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123, P. R. China
| | - Kazunori Fujisawa
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
| | - Ana Laura Elías
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
| | - Yu Lei
- Department of Material Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Nestor Perea-López
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
| | - Morinobu Endo
- Institute of Carbon Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Minghu Pan
- School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P. R. China
| | - Marcos A. Pimenta
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil
| | - Mauricio Terrones
- Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Material Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
- Institute of Carbon Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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