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Sloboda T, Johansson FOL, Kammlander B, Berggren E, Svanström S, Fernández AG, Lindblad A, Cappel UB. Unravelling the ultrafast charge dynamics in PbS quantum dots through resonant Auger mapping of the sulfur K-edge. RSC Adv 2022; 12:31671-31679. [PMID: 36380927 PMCID: PMC9634717 DOI: 10.1039/d2ra06091d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
There is a great fundamental interest in charge dynamics of PbS quantum dots, as they are promising for application in photovoltaics and other optoelectronic devices. The ultrafast charge transport is intriguing, offering insight into the mechanism of electron tunneling processes within the material. In this study, we investigated the charge transfer times of PbS quantum dots of different sizes and non-quantized PbS reference materials by comparing the propensity of localized or delocalized decays of sulfur 1s core hole states excited by X-rays. We show that charge transfer times in PbS quantum dots decrease with excitation energy and are similar at high excitation energy for quantum dots and non-quantized PbS. However, at low excitation energies a distinct difference in charge transfer time is observed with the fastest charge transfer in non-quantized PbS and the slowest in the smallest quantum dots. Our observations can be explained by iodide ligands on the quantum dots creating a barrier for charge transfer, which reduces the probability of interparticle transfer at low excitation energies. The probability of intraparticle charge transfer is limited by the density of available states which we describe according to a wave function in a quantum well model. The stronger quantum confinement effect in smaller PbS quantum dots is manifested as longer charge transfer times relative to the larger quantum dots at low excitation energies.
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Affiliation(s)
- Tamara Sloboda
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology SE-100 44 Stockholm Sweden
| | - Fredrik O L Johansson
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology SE-100 44 Stockholm Sweden
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP F-75005 Paris France
| | - Birgit Kammlander
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology SE-100 44 Stockholm Sweden
| | - Elin Berggren
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University Box 516 751 20 Uppsala Sweden
| | - Sebastian Svanström
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University Box 516 751 20 Uppsala Sweden
| | - Alberto García Fernández
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology SE-100 44 Stockholm Sweden
| | - Andreas Lindblad
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University Box 516 751 20 Uppsala Sweden
| | - Ute B Cappel
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology SE-100 44 Stockholm Sweden
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Analysis of the effects of simplifications on the state of loads in a centrifugal compressor. Sci Rep 2022; 12:16892. [PMID: 36207406 PMCID: PMC9546889 DOI: 10.1038/s41598-022-20753-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/19/2022] [Indexed: 12/03/2022] Open
Abstract
This study aims to quantify and assess qualitatively the impact of modeling simplifications used to represent inertial and aerodynamic loads on the stresses and structural deformations of a centrifugal compressor in operation. The research object is the compressor of the high-pressure line of the DGEN 380 bypass turbine engine. Based on the virtual dynamometer WESTT CS/BV, the gas-dynamic parameters at the entrance to the centrifugal compressor and after the stage are determined. These values were used as initial parameters for numerical flow analysis. As part of the numerical strength analyses, a series of several load configurations were carried out: spin only, spin and inlet pressure normally applied on the working surface of the rotor blade, spin and outlet pressure normally applied on the working surface of the rotor blade, and one-way fluid–structure interaction analysis taking into account the aerodynamic loads with and without spinning. Based on the simulations, the level of similarity of a given load configuration with the last analysis, adopted as the reference, was determined. It was observed that in terms of the stress state, the rotational analysis taking into account the pressure on both sides of the blade gives satisfactory results, but the strain values are overestimated. The results obtained and the method of evaluation of compressor results can be used in research in the area of aviation, automotive, and refrigeration industries.
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Bowler DE, Bhandari N, Repke L, Beuthner C, Callaghan CT, Eichenberg D, Henle K, Klenke R, Richter A, Jansen F, Bruelheide H, Bonn A. Decision-making of citizen scientists when recording species observations. Sci Rep 2022; 12:11069. [PMID: 35773384 PMCID: PMC9245884 DOI: 10.1038/s41598-022-15218-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 06/21/2022] [Indexed: 11/16/2022] Open
Abstract
Citizen scientists play an increasingly important role in biodiversity monitoring. Most of the data, however, are unstructured—collected by diverse methods that are not documented with the data. Insufficient understanding of the data collection processes presents a major barrier to the use of citizen science data in biodiversity research. We developed a questionnaire to ask citizen scientists about their decision-making before, during and after collecting and reporting species observations, using Germany as a case study. We quantified the greatest sources of variability among respondents and assessed whether motivations and experience related to any aspect of data collection. Our questionnaire was answered by almost 900 people, with varying taxonomic foci and expertise. Respondents were most often motivated by improving species knowledge and supporting conservation, but there were no linkages between motivations and data collection methods. By contrast, variables related to experience and knowledge, such as membership of a natural history society, were linked with a greater propensity to conduct planned searches, during which typically all species were reported. Our findings have implications for how citizen science data are analysed in statistical models; highlight the importance of natural history societies and provide pointers to where citizen science projects might be further developed.
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Affiliation(s)
- Diana E Bowler
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103, Leipzig, Germany. .,Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Str. 159, 07743, Jena, Germany. .,Department of Ecosystem Services, Helmholtz-Center for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany.
| | - Netra Bhandari
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103, Leipzig, Germany
| | - Lydia Repke
- Department of Survey Design and Methodology, GESIS - Leibniz Institute for the Social Sciences, P.O. Box 12 21 55, 68072, Mannheim, Germany
| | - Christoph Beuthner
- Department of Survey Design and Methodology, GESIS - Leibniz Institute for the Social Sciences, P.O. Box 12 21 55, 68072, Mannheim, Germany
| | - Corey T Callaghan
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103, Leipzig, Germany.,Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108, Halle, Germany
| | - David Eichenberg
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103, Leipzig, Germany.,Department of Ecosystem Services, Helmholtz-Center for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Klaus Henle
- Department of Conservation Biology & Social-Ecological Systems, Helmholtz-Center for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Reinhard Klenke
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103, Leipzig, Germany.,Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108, Halle, Germany
| | - Anett Richter
- Thünen Institute of Biodiversity, Bundesallee 65, 38116, Braunschweig, Germany
| | - Florian Jansen
- Faculty of Agricultural and Environmental Sciences, University of Rostock, Justus-von-Liebig-Weg 6, 18059, Rostock, Germany
| | - Helge Bruelheide
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103, Leipzig, Germany.,Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108, Halle, Germany
| | - Aletta Bonn
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103, Leipzig, Germany.,Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Str. 159, 07743, Jena, Germany.,Department of Ecosystem Services, Helmholtz-Center for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
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Xing CY, Zhang YZ, Hu W, Zhao LY. LINC00313 facilitates osteosarcoma carcinogenesis and metastasis through enhancing EZH2 mRNA stability and EZH2-mediated silence of PTEN expression. Cell Mol Life Sci 2022; 79:382. [PMID: 35751755 PMCID: PMC11073393 DOI: 10.1007/s00018-022-04376-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 05/13/2022] [Indexed: 12/25/2022]
Abstract
BACKGROUND Osteosarcoma is one of the five leading causes of cancer death among all pediatric malignancies. Recent advances in non-coding RNAs suggested that many long noncoding RNAs (lncRNAs) are dysregulated in cancer tissues and play important roles in carcinogenesis. We aimed to further explore the mechanisms of Long Intergenic Non-Protein Coding RNA 313 (LINC00313)-promoted malignant phenotypes of osteosarcoma. METHODS The mRNA expressions were determined by quantitative real-time PCR. Protein levels were detected using Western blotting or immunohistochemistry staining. Protein binding to genomic DNA and RNA were measured using chromatin and RNA immunoprecipitation assay, respectively. CCK-8 and EdU incorporation assay were adopted to detect cell proliferation. Transwell assay was employed to assess the capacity of cell migration and invasion. The roles of LINC00313 and its target genes in tumorigenesis and metastasis of osteosarcoma were evaluated using subcutaneous xenograft models and tail vein inoculation models. RESULTS LINC00313 was elevated in osteosarcoma tissues compared with adjacent normal tissues. Higher LINC00313 was associated with advanced grades of osteosarcoma. LINC00313 promoted cell proliferation, migration, invasion in vitro and tumor growth as well as metastasis in vivo through inhibiting PTEN expression to promote AKT phosphorylation. Mechanistically, LINC00313 favored the interaction between FUS and EZH2, leading to the prolonged half-life of EZH2 mRNA, thereby in turn up-regulating EZH2 proteins and increasing EZH2-mediated epigenetic silence of PTEN. CONCLUSION LINC00313 exerted oncogene-like actions through increasing EZH2 mRNA stability, leading to PTEN deficiency in osteosarcoma.
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Affiliation(s)
- Chun-Yang Xing
- Department of Orthopedics, First Affiliated Hospital, College of Medicine, Zhejiang University, No. 79, Qingchun Road, Hangzhou, 310003, Zhejiang Province, China.
| | - Yu-Zhu Zhang
- Department of Orthopedics, First Affiliated Hospital, College of Medicine, Zhejiang University, No. 79, Qingchun Road, Hangzhou, 310003, Zhejiang Province, China
| | - Wei Hu
- Department of Radiotherapy, The People's Hospital of Changxing County, Huzhou, 313199, Zhejiang Province, China
| | - Li-Yuan Zhao
- Department of Emergency, Qilu Hospital, Shandong University, Jinan, 250063, Shandong Province, China
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Sloboda T, Svanström S, Johansson FOL, Bryngelsson E, García-Fernández A, Lindblad A, Cappel UB. The impact of chemical composition of halide surface ligands on the electronic structure and stability of lead sulfide quantum dot materials. Phys Chem Chem Phys 2022; 24:12645-12657. [PMID: 35579959 DOI: 10.1039/d2cp01050j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
There is a high fundamental interest in the surface and bulk chemistry of quantum dot (QD) solids, as they have proven to be very promising materials in optoelectronic devices. The choice of surface ligands for quantum dots in solid devices determines many of the film properties, as the ligands influence for example the doping density, chemical stability and charge transport. Lead halide ligands have developed as the main ligand of choice for lead sulfide quantum dots, as they have been shown to passivate quantum dot surfaces and enhance the chemical stability. In this study, we successfully varied the ligand composition on the surface of PbS quantum dot films from pure lead iodide to pure lead bromide and investigated its influence on the chemical and electronic structure of the QD solids using hard X-ray photoelectron spectroscopy (HAXPES). Furthermore, we developed a surface treatment to prevent the surface oxidation of a bulk PbS reference sample. Through measurements of this sample and of lead halide reference samples, we were able to assign the contributions of different chemical bonding to the Pb 4f core level and of different atomic orbitals to the valence band spectral shape of the QD materials. Overall, we found that the valence band edge position was very similar for all different iodide:bromide ratios and that all investigated compositions were able to protect the quantum dot surfaces within solid films from oxidation. However, the ligand composition significantly influences the sample stability under X-rays. The iodide rich QD solids showed the highest stability with very little to no chemical changes over several hours of X-ray exposure, while the bromide rich QD solids changed already within the first hour of exposure.
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Affiliation(s)
- Tamara Sloboda
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Sebastian Svanström
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden
| | - Fredrik O L Johansson
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden
| | - Erik Bryngelsson
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Alberto García-Fernández
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Andreas Lindblad
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden
| | - Ute B Cappel
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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Clark PCJ, Lewis NK, Ke JCR, Ahumada-Lazo R, Chen Q, Neo DCJ, Gaulding EA, Pach GF, Pis I, Silly MG, Flavell WR. Surface band bending and carrier dynamics in colloidal quantum dot solids. NANOSCALE 2021; 13:17793-17806. [PMID: 34668501 DOI: 10.1039/d1nr05436h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Band bending in colloidal quantum dot (CQD) solids has become important in driving charge carriers through devices. This is typically a result of band alignments at junctions in the device. Whether band bending is intrinsic to CQD solids, i.e. is band bending present at the surface-vacuum interface, has previously been unanswered. Here we use photoemission surface photovoltage measurements to show that depletion regions are present at the surface of n and p-type CQD solids with various ligand treatments (EDT, MPA, PbI2, MAI/PbI2). Using laser-pump photoemission-probe time-resolved measurements, we show that the timescale of carrier dynamics in the surface of CQD solids can vary over at least 6 orders of magnitude, with the fastest dynamics on the order of microseconds in PbS-MAI/PbI2 solids and on the order of seconds for PbS-MPA and PbS-PbI2. By investigating the surface chemistry of the solids, we find a correlation between the carrier dynamics timescales and the presence of oxygen contaminants, which we suggest are responsible for the slower dynamics due to deep trap formation.
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Affiliation(s)
- Pip C J Clark
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Nathan K Lewis
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Jack Chun-Ren Ke
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Ruben Ahumada-Lazo
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Qian Chen
- Department of Materials, The University of Manchester, Manchester M13 9PL, UK
| | - Darren C J Neo
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, USA
| | | | - Gregory F Pach
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Igor Pis
- Laboratorio TASC, IOM CNR, S.S. 14 km 163.5, 34149 Basovizza, Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., S. S. 14 Km 163.5, 34149 Basovizza, Trieste, Italy
| | - Mathieu G Silly
- Synchrotron SOLEIL, BP 48, Saint-Aubin, F91192 Gif sur Yvette CEDEX, France
| | - Wendy R Flavell
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
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