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Makin RA, York KR, Messecar AS, Durbin SM. Quantitative Disorder Analysis and Particle Removal Efficiency of Polypropylene-Based Masks. MRS Advances 2020; 5:2853-2861. [PMID: 33437530 PMCID: PMC7790047 DOI: 10.1557/adv.2020.346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We demonstrate a methodology for predicting particle removal efficiency of polypropylene-based filters used in personal protective equipment, based on quantification of disorder in the context of methyl group orientation as structural motifs in conjunction with an Ising model. The corresponding Bragg-Williams order parameter is extracted through either Raman spectro-scopy or scanning electron microscopy. Temperature-dependent analysis verifies the presence of an order-disorder transition, and the methodology is applied to published data for multiple samples. The result is a method for predicting the particle removal efficiency of filters used in masks based on a material-level property.
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Affiliation(s)
- R. A. Makin
- Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, MI 49008 USA
| | - K. R. York
- Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, MI 49008 USA
| | - A. S. Messecar
- Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, MI 49008 USA
| | - S. M. Durbin
- Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, MI 49008 USA
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Mason JA, Davison-Versagli CA, Leliaert AK, Pape DJ, McCallister C, Zuo J, Durbin SM, Buchheit CL, Zhang S, Schafer ZT. Oncogenic Ras differentially regulates metabolism and anoikis in extracellular matrix-detached cells. Cell Death Differ 2016; 23:1271-82. [PMID: 26915296 DOI: 10.1038/cdd.2016.15] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/09/2015] [Accepted: 01/25/2016] [Indexed: 12/14/2022] Open
Abstract
In order for cancer cells to survive during metastasis, they must overcome anoikis, a caspase-dependent cell death process triggered by extracellular matrix (ECM) detachment, and rectify detachment-induced metabolic defects that compromise cell survival. However, the precise signals used by cancer cells to facilitate their survival during metastasis remain poorly understood. We have discovered that oncogenic Ras facilitates the survival of ECM-detached cancer cells by using distinct effector pathways to regulate metabolism and block anoikis. Surprisingly, we find that while Ras-mediated phosphatidylinositol (3)-kinase signaling is critical for rectifying ECM-detachment-induced metabolic deficiencies, the critical downstream effector is serum and glucocorticoid-regulated kinase-1 (SGK-1) rather than Akt. Our data also indicate that oncogenic Ras blocks anoikis by diminishing expression of the phosphatase PHLPP1 (PH Domain and Leucine-Rich Repeat Protein Phosphatase 1), which promotes anoikis through the activation of p38 MAPK. Thus, our study represents a novel paradigm whereby oncogene-initiated signal transduction can promote the survival of ECM-detached cells through divergent downstream effectors.
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Affiliation(s)
- J A Mason
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - C A Davison-Versagli
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - A K Leliaert
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - D J Pape
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - C McCallister
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - J Zuo
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - S M Durbin
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - C L Buchheit
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - S Zhang
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Z T Schafer
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
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Linhart WM, Chai J, Morris RJH, Dowsett MG, McConville CF, Durbin SM, Veal TD. Giant reduction of InN surface electron accumulation: compensation of surface donors by Mg dopants. Phys Rev Lett 2012; 109:247605. [PMID: 23368381 DOI: 10.1103/physrevlett.109.247605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Indexed: 06/01/2023]
Abstract
Extreme electron accumulation with sheet density greater than 10(13) cm(-2) is almost universally present at the surface of indium nitride (InN). Here, x-ray photoemission spectroscopy and secondary ion mass spectrometry are used to show that the surface Fermi level decreases as the Mg concentration increases, with the sheet electron density falling to below 10(8) cm(-2). Surface space-charge calculations indicate that the lowering of the surface Fermi level increases the density of unoccupied donor-type surface states and that these are largely compensated by Mg acceptors in the near-surface hole depletion region rather than by accumulated electrons. This is a significant step towards the realization of InN-based optoelectronic devices.
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Affiliation(s)
- W M Linhart
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
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Abstract
Ultrafast dynamics in atomic, molecular and condensed-matter systems are increasingly being studied using optical-pump, X-ray probe techniques where subpicosecond laser pulses excite the system and X-rays detect changes in absorption spectra and local atomic structure(1-3). New opportunities are appearing as a result of improved synchrotron capabilities and the advent of X-ray free-electron lasers(4,5). These source improvements also allow for the reverse measurement: X-ray pump followed by optical probe. We describe here how an X-ray pump beam transforms a thin GaAs specimen from a strong absorber into a nearly transparent window in less than 100 ps, for laser photon energies just above the bandgap. We find the opposite effect-X-ray induced optical opacity-for photon energies just below the bandgap. This raises interesting questions about the ultrafast many-body response of semiconductors to X-ray absorption, and provides a new approach for an X-ray/optical cross-correlator for synchrotron and X-ray free-electron laser applications.
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Affiliation(s)
- S. M. Durbin
- Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA
| | - T. Clevenger
- Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA
| | - T. Graber
- The Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, USA
| | - R. Henning
- The Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, USA
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Petravic M, Deenapanray PNK, Fraser MD, Soldatov AV, Yang YW, Anderson PA, Durbin SM. Direct Observation of Defect Levels in InN by Soft X-ray Absorption Spectroscopy. J Phys Chem B 2006; 110:2984-7. [PMID: 16494298 DOI: 10.1021/jp057140l] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have used synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to study the electronic structure of nitrogen-related defects in InN(0001). Several defect levels within the band gap or the conduction band of InN were clearly resolved in NEXAFS spectra around the nitrogen K-edge. We attribute the level observed at 0.3 eV below the conduction band minimum (CBM) to interstitial nitrogen, the level at 1.7 eV above the CBM to antisite nitrogen, and a sharp resonance at 3.2 eV above the CBM to molecular nitrogen, in full agreement with theoretical simulations.
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Walsby ED, Wang S, Ferguson B, Xu J, Yuan T, Blaikie R, Durbin SM, Cumming DRS, Zhang XC. Investigation of a THz Fresnel lens. ACTA ACUST UNITED AC 2003. [DOI: 10.1007/978-3-642-59319-2_91] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Wang S, Yuan T, Walsby ED, Blaikie RJ, Durbin SM, Cumming DRS, Xu J, Zhang XC. Characterization of T-ray binary lenses. Opt Lett 2002; 27:1183-1185. [PMID: 18026401 DOI: 10.1364/ol.27.001183] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Multilevel phase-shift Fresnel diffractive zone plates fabricated on silicon wafers have been used as T-ray imaging lenses. The imaging results, including spatial and temporal distribution of T-rays measured at the focal planes in the frequency range from 0.5 to 1.5 THz, indicate that the performance of the diffractive terahertz (THz) lens is comparable with or better than that of conventional refractive THz lenses. The unique properties of the T-ray binary lens make it possible to fabricate excellent optics for narrow-band THz applications.
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Sage JT, Durbin SM, Sturhahn W, Wharton DC, Champion PM, Hession P, Sutter J, Alp EE. Long-range reactive dynamics in myoglobin. Phys Rev Lett 2001; 86:4966-4969. [PMID: 11384393 DOI: 10.1103/physrevlett.86.4966] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/1999] [Indexed: 05/23/2023]
Abstract
We report the complete vibrational spectrum of the probe nucleus 57Fe at the oxygen-binding site of the protein myoglobin. The Fe-pyrrole nitrogen stretching modes of the heme group, identified here, probe asymmetric interactions with the protein environment. Collective oscillations of the polypeptide, rather than localized heme vibrations, dominate the low frequency region. We conclude that the heme "doming" mode is significantly delocalized, so that distant sites respond to oxygen binding on vibrational time scales. This has ramifications for understanding long-range interactions in biomolecules, such as those that mediate cooperativity in allosteric proteins.
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Affiliation(s)
- J T Sage
- Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA
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Bakulin AS, Durbin SM, Jach T, Pedulla J. Fast imaging of hard x rays with a laboratory microscope. Appl Opt 2000; 39:3333-3337. [PMID: 18349901 DOI: 10.1364/ao.39.003333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An improved x-ray microscope with a fully electronic CCD detector system has been constructed that allows improved laboratory-based microstructural investigations of materials with hard x rays. It uses the Kirkpatrick-Baez multilayer mirror design to form an image that has a demonstrated resolution of 4 microm at 8 keV (Cu K(alpha) radiation). This microscope performs well with standard sealed-tube laboratory x-ray sources, producing digital images with 20-s exposure times for a 5-microm Au grid (a thickness of two absorption lengths).
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Affiliation(s)
- A S Bakulin
- Department of Physics, Purdue University, West Lafayette, Indiana 47907-1396, USA
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Chowdhury TA, Dyer PH, Bartlett WA, Legge ES, Durbin SM, Barnett AH, Bain SC. Glomerular filtration rate determination in diabetic patients using iohexol clearance--comparison of single and multiple plasma sampling methods. Clin Chim Acta 1998; 277:153-8. [PMID: 9853698 DOI: 10.1016/s0009-8981(98)00116-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Use of iohexol clearance has been described as the gold standard for the measurement of glomerular filtration rate (GFR). It is suggested that multiple plasma sampling following iohexol injection is required to accurately determine GFR by area under plasma clearance curve. The aim of this study was to determine whether single plasma sampling 4 h after injection of iohexol could accurately determine GFR in diabetic patients with mild to moderate renal failure, compared to multiple plasma sampling. A total of 120 GFR determinations in 36 patients with non-insulin dependent diabetic renal disease were done over 1 year. No acute deterioration was seen in renal function following injection of contrast in any patient. Strong correlation in GFR measurement was observed between the multiple plasma sampling method and the single plasma sampling method (r2 = 0.975). Single plasma sampling 4 h after bolus injection of iohexol is a safe and accurate method of determining GFR and change in GFR in diabetic subjects with mild to moderate renal impairment.
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Affiliation(s)
- T A Chowdhury
- Department of Medicine, Birmingham Heartlands Hospital, UK
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Hoffman SA, Castro MA, Follis GC, Durbin SM. X-ray-diffraction determination of the Ni-dopant site in single-crystal YBa2Cu3O7- delta. Phys Rev B Condens Matter 1994; 49:12170-12175. [PMID: 10010091 DOI: 10.1103/physrevb.49.12170] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Pelekanos N, Ding J, Fu Q, Nurmikko AV, Durbin SM, Kobayashi M, Gunshor RL. Hot-exciton luminescence in ZnTe/MnTe quantum wells. Phys Rev B Condens Matter 1991; 43:9354-9357. [PMID: 9996626 DOI: 10.1103/physrevb.43.9354] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Hoffman SA, Venkatraman C, Ehrlich SN, Durbin SM, Liedl GL. Structural and transport measurements in La1.8Sr0.2NiO4+ delta. Phys Rev B Condens Matter 1991; 43:7852-7858. [PMID: 9996405 DOI: 10.1103/physrevb.43.7852] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Durbin SM, Berman LE, Batterman BW, Brodsky MB, Hamaker HC. Epitaxial growth of fcc Cr on Au(100). Phys Rev B Condens Matter 1988; 37:6672-6675. [PMID: 9943934 DOI: 10.1103/physrevb.37.6672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Durbin SM, Berman LE, Batterman BW, Blakely JM. X-ray standing-wave determination of surface structure: Au on Si(111). Phys Rev B Condens Matter 1986; 33:4402-4405. [PMID: 9938895 DOI: 10.1103/physrevb.33.4402] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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