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Articles 1 - 30 of 38
Full-Text Articles in Nanoscience and Nanotechnology
Ultrafine Nife2o4 Powder Fabricated From Reverse Microemulsion Process, Jiye Fang, Narayan Shama, Le Duc Tung, Eun Young Shin, Charles J. O'Connor, Kevin L. Stokes, Gabriel Caruntu, John B. Wiley, Leonard Spinu, Jinke Tang
Ultrafine Nife2o4 Powder Fabricated From Reverse Microemulsion Process, Jiye Fang, Narayan Shama, Le Duc Tung, Eun Young Shin, Charles J. O'Connor, Kevin L. Stokes, Gabriel Caruntu, John B. Wiley, Leonard Spinu, Jinke Tang
Jinke Tang
NiFe2O4 ultrafine powder with high crystallinity has been prepared through a reverse microemulsion route. The composition in starting solution was optimized, and the resulting NiFe2O4 was formed at temperature of around 550–600 °C, which is much lower than that observed from the solid-state reaction. Magnetic investigation indicates that samples are soft-magnetic materials with low coercivity and with the saturation magnetization close to the bulk value of Ni ferrite.
Refractory Plasmonics With Titanium Nitride: Broadband Metamaterial Absorber, W Li, U. Guler, N. Kinsey, G. Naik, A. Boltasseva, J. Guan, V Shalaev, A. Kildishev
Refractory Plasmonics With Titanium Nitride: Broadband Metamaterial Absorber, W Li, U. Guler, N. Kinsey, G. Naik, A. Boltasseva, J. Guan, V Shalaev, A. Kildishev
U. Guler
A high-temperature stable broadband plasmonic absorber is designed, fabricated, and optically characterized. A broadband absorber with an average high absorption of 95% and a total thickness of 240 nm is fabricated, using a refractory plasmonic material, titanium nitride. This absorber integrates both the plasmonic resonances and the dielectric-like loss. It opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits.
Multiscale Contact Mechanics Model For Rf-Mems Switches With Quantified Uncertainties, Hojin Kim, Nurul Shaik, Xin Xu, Arvind Raman, Alejandro Strachan
Multiscale Contact Mechanics Model For Rf-Mems Switches With Quantified Uncertainties, Hojin Kim, Nurul Shaik, Xin Xu, Arvind Raman, Alejandro Strachan
Xin Xu
We introduce a multiscale model for contact mechanics between rough surfaces and apply it to characterize the force-displacement relationship for a metal-dielectric contact relevant for radio frequency micro-electromechanicl system (MEMS) switches. We propose a mesoscale model to describe the history-dependent force-displacement relationships in terms of the surface roughness, the long-range attractive interaction between the two surfaces, and the repulsive interaction between contacting asperities (including elastic and plastic deformation). The inputs to this model are the experimentally determined surface topography and the Hamaker constant as well as the mechanical response of individual asperities obtained from density functional theory calculations and large-scale …
Origins Of Phase Contrast In The Atomic Force Microscope In Liquids, John Melcher, Carolina Carrasco, Xin Xu, Jose L. Carrascosa, Julio Gomez-Herrero, Pedro Jose De Pablo, Arvind Raman
Origins Of Phase Contrast In The Atomic Force Microscope In Liquids, John Melcher, Carolina Carrasco, Xin Xu, Jose L. Carrascosa, Julio Gomez-Herrero, Pedro Jose De Pablo, Arvind Raman
Xin Xu
We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) in liquids where low-stiffness microcantilever probes are often used for nanoscale imaging of soft biological samples with gentle forces. Under these conditions, we show that the phase contrast derives primarily from a unique energy flow channel that opens up in liquids due to the momentary excitation of higher eigenmodes. Contrary to the common assumption, phase-contrast images in liquids using soft microcantilevers are often maps of short-range conservative interactions, such as local elastic response, rather than tip-sample dissipation. The theory is used to demonstrate variations in local …
Compositional Contrast Of Biological Materials In Liquids Using The Momentary Excitation Of Higher Eigenmodes In Dynamic Atomic Force Microscopy, Xin Xu, John Melcher, Sudipta Basak, R. Reifenberger, Arvind Raman
Compositional Contrast Of Biological Materials In Liquids Using The Momentary Excitation Of Higher Eigenmodes In Dynamic Atomic Force Microscopy, Xin Xu, John Melcher, Sudipta Basak, R. Reifenberger, Arvind Raman
Xin Xu
Atomic Force microscope (AFM) cantilevers commonly used for imaging soft biological samples in liquids experience a momentary excitation of the higher eigenmodes at each tap. This transient response is very sensitive to the local sample elasticity under gentle imaging conditions because the higher eigenmode time period is comparable to the tip-sample contact time. By mapping the momentary excitation response, we demonstrate a new scanning probe spectroscopy capable of resolving with high sensitivity the variations in the elasticity of soft biological materials in liquids.
Dynamics Of Surface-Coupled Microcantilevers In Force Modulation Atomic Force Microscopy - Magnetic Vs. Dither Piezo Excitation, Xin Xu, Marisol Koslowski, Arvind Raman
Dynamics Of Surface-Coupled Microcantilevers In Force Modulation Atomic Force Microscopy - Magnetic Vs. Dither Piezo Excitation, Xin Xu, Marisol Koslowski, Arvind Raman
Xin Xu
Force modulation atomic force microscopy is widely used for mapping the nanoscale mechanical properties of heterogeneous or composite materials using low frequency excitation of a microcantilever scanning the surface. Here we show that the excitation mode - magnetic or dither piezo, has a major influence on the surface-coupled microcantilever dynamics. Not only is the observed material property contrast inverted between these excitation modes but also the frequency response of the surface-coupled cantilever in the magnetic mode is near-ideal with a clear resonance peak and little phase distortion thus enabling quantitative mapping of the local mechanical properties. (C) 2012 American Institute …
Atomic Force Microscopy Characterization Of Cellulose Nanocrystals, Roya Lahiji, Xin Xu, R. Reifenberger, Arvind Raman, Alan Rudie, Robert Moon
Atomic Force Microscopy Characterization Of Cellulose Nanocrystals, Roya Lahiji, Xin Xu, R. Reifenberger, Arvind Raman, Alan Rudie, Robert Moon
Xin Xu
Cellulose nanocrystals (CNCs) are gaining interest as a "green" nanomaterial with superior mechanical and chemical properties for high-performance nanocomposite materials; however, there is a lack of accurate material property characterization of individual CNCs. Here, a detailed Study of the topography, elastic and adhesive properties of individual wood-derived CNCs is performed using atomic force microscopy (AFM). AFM experiments involving high-resolution dynamic mode imaging and jump-mode measurements were performed on individual CNCs under ambient conditions with 30% relative humidity (RH) and under a N-2 atmosphere with 0.1% RH. A procedure was also developed to calculate the CNC transverse elastic modulus (E-T) by …
Accurate Force Spectroscopy In Tapping Mode Atomic Force Microscopy In Liquids, Xin Xu, John Melcher, Arvind Raman
Accurate Force Spectroscopy In Tapping Mode Atomic Force Microscopy In Liquids, Xin Xu, John Melcher, Arvind Raman
Xin Xu
Existing force spectroscopy methods in tapping mode atomic force microscopy (AFM) such as higher harmonic inversion [M. Stark, R. W. Stark, W. M. Heckl, and R. Guckenberger, Proc. Natl. Acad. Sci. U. S. A. 99, 8473 (2002)] or scanning probe acceleration microscopy [J. Legleiter, M. Park, B. Cusick, and T. Kowalewski, Proc. Natl. Acad. Sci. U. S. A. 103, 4813 (2006)] or integral relations [M. Lee and W. Jhe, Phys. Rev. Lett. 97, 036104 (2006); S. Hu and A. Raman, Nanotechnology 19, 375704 (2008); H. Holscher, Appl. Phys. Lett. 89, 123109 (2006); A. J. Katan, Nanotechnology 20, 165703 (2009)] require …
Au@Tio2 Nanocomposites For The Catalytic Degradation Of Methyl Orange And Methylene Blue: An Electron Relay Effect, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho
Au@Tio2 Nanocomposites For The Catalytic Degradation Of Methyl Orange And Methylene Blue: An Electron Relay Effect, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho
Dr. Mohammad Mansoob Khan
Au@TiO2 nanocomposites were used for the catalytic degradation of methyl orange and methylene blue by NaBH4. A detail pathway for step by step reduction, oxidation and complete mineralization of intermediates into the respective end-products was established by UV-vis spectroscopy, chemical oxygen demand, ion chromatography and cyclic voltammetry (CV). CV studies confirmed that the dyes were reduced and oxidized to the end-products by NaBH4 in the presence of Au@TiO2 nanocomposites and O2•, •OH and HO2• radicals generated in-situ. Results suggest that Au@TiO2 nanocomposites not only assist in the decolorization of dyes, but also promote their complete mineralization into harmless end-products.
Large Scale, Highly Dense Nanoholes On Metal Surfaces By Underwater Laser Assisted Hydrogen Etching Near Nanocrystalline Boundary, Dong Lin, Martin Yi Zhang, Chang Ye, Zhikun Liu, Richard Liu, Gary Cheng
Large Scale, Highly Dense Nanoholes On Metal Surfaces By Underwater Laser Assisted Hydrogen Etching Near Nanocrystalline Boundary, Dong Lin, Martin Yi Zhang, Chang Ye, Zhikun Liu, Richard Liu, Gary Cheng
dong lin
A new method to generate large scale and highly dense nanoholes is presented in this paper. By the pulsed laser irradiation under water, the hydrogen etching is introduced to form high density nanoholes on the surfaces of AISI 4140 steel and Ti. In order to achieve higher nanohole density, laser shock peening (LSP) followed by recrystallization is used for grain refinement. It is found that the nanohole density does not increase until recrystallization of the substructures after laser shock peening. The mechanism of nanohole generation is studied in detail. This method can be also applied to generate nanoholes on other …
Laser Assisted Embedding Of Nanoparticles Into Metallic Materials, Dong Lin, Sergey Suslov, Chang Ye, Yiliang Liao, C. Richard Liu, Gary Cheng
Laser Assisted Embedding Of Nanoparticles Into Metallic Materials, Dong Lin, Sergey Suslov, Chang Ye, Yiliang Liao, C. Richard Liu, Gary Cheng
dong lin
This paper reports a methodology of half-embedding nanoparticles into metallic materials. Transparent and opaque nanoparticles are chosen to demonstrate the process of laser assisted nanoparticle embedding. Dip coating method is used to coat transparent or opaque nanoparticle on the surface of metallic material. Nanoparticles are embedded into substrate by laser irradiation. In this study, the mechanism and process of nanoparticle embedding are investigated. It is found both transparent and opaque nanoparticles embedding are with high densities and good uniformities. (C) 2011 Elsevier B. V. All rights reserved.
Magnetic Field Assisted Growth Of Highly Dense Alpha-Fe2o3 Single Crystal Nanosheets And Their Application In Water Treatment, Dong Lin, Biwei Deng, Stephen Sassman, Yaowu Hu, Sergey Suslov, Gary Cheng
Magnetic Field Assisted Growth Of Highly Dense Alpha-Fe2o3 Single Crystal Nanosheets And Their Application In Water Treatment, Dong Lin, Biwei Deng, Stephen Sassman, Yaowu Hu, Sergey Suslov, Gary Cheng
dong lin
Highly dense 2D nanostructures are desirable in photocatalysis, water treatment and energy storage, due to their high surface to volume areas. This paper describes a novel approach combining thermal stress and magnetic force to generate highly dense alpha-Fe2O3 nanosheets on the surface of various iron substrates, including plates and powders. This technique involves the thermal oxidation of iron substrates on a hot plate with a magnetic field. The Lorentz force acting on the ions induced by the magnetic field facilitates the lateral growth of nanosheets. This effect results in a highly porous nanostructure consisting of dense 2D nanosheets with extremely …
Mechanism Of Fatigue Performance Enhancement In A Laser Sintered Superhard Nanoparticles Reinforced Nanocomposite Followed By Laser Shock Peening, Dong Lin, Chang Ye, Yiliang Liao, Sergey Suslov, Richard Liu, Gary J. Cheng
Mechanism Of Fatigue Performance Enhancement In A Laser Sintered Superhard Nanoparticles Reinforced Nanocomposite Followed By Laser Shock Peening, Dong Lin, Chang Ye, Yiliang Liao, Sergey Suslov, Richard Liu, Gary J. Cheng
dong lin
This study investigates the fundamental mechanism of fatigue performance enhancement during a novel hybrid manufacturing process, which combines laser sintering of superhard nanoparticles integrated nanocomposites and laser shock peening (LSP). Through laser sintering, TiN nanoparticles are integrated uniformly into iron matrix to form a nanocomposite layer near the surface of AISI4140 steel. LSP is then performed on the nanocomposite layer to generate interaction between nanoparticles and shock waves. The fundamental mechanism of fatigue performance enhancement is discussed in this paper. During laser shock interaction with the nanocomposites, the existence of nanoparticles increases the dislocation density and also helps to pin …
Direct Writing Of Au Nanoneedles Array On Glass By Confined Laser Spinning, Yingling Yang, Dong Lin, Gary J. Cheng
Direct Writing Of Au Nanoneedles Array On Glass By Confined Laser Spinning, Yingling Yang, Dong Lin, Gary J. Cheng
dong lin
Generation of gold nanoneedles on glass by confined laser spinning was explored by using a nanosecond pulsed laser. When the coated Au thin film was irradiated under the confinement of glass, gold nanoneedles were formed by spreading the molten liquid of gold under high pressure. The mechanism of the confined laser spinning process is studied. The maximum velocity and instability of molten liquid during confined laser spinning were estimated. The diameter of nanoneedles can be controlled by changing the thickness of coated gold thin film. Large scale of gold nanoneedles can be formed by this direct writing method and collected …
Laser Sintering Of Separated And Uniformly Distributed Multiwall Carbon Nanotubes Integrated Iron Nanocomposites, Dong Lin, Chunghorng Richard Liu, Gary J. Cheng
Laser Sintering Of Separated And Uniformly Distributed Multiwall Carbon Nanotubes Integrated Iron Nanocomposites, Dong Lin, Chunghorng Richard Liu, Gary J. Cheng
dong lin
Uniform distribution of carbon nanotubes (CNTs) in metal matrix during additive manufacturing of nanocomposites is always a challenge since the CNTs tend to aggregate in the molten pool. In this study, Multiwall carbon nanotubes (MWNTs) were separated and distributed uniformly into iron matrix by laser sintering process. MWNTs and iron powders were mixed together by magnetic stir, coated on steel 4140 surface, followed by laser sintering. Due to the fast heating and cooling rate, the CNTs are evenly distributed in the metal matrix. The temperature field was calculated by multiphysics simulation considering size effects, including size dependent melting temperature, thermal …
Highly Visible Light Active Ag@Zno Nanocomposites Synthesized By Gel-Combustion Route, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho
Highly Visible Light Active Ag@Zno Nanocomposites Synthesized By Gel-Combustion Route, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho
Dr. Mohammad Mansoob Khan
Highly visible light active 1% and 3% Ag@ZnO nanocomposites were synthesized via a gel combustion route using citric acid as a fuel. The formation of the nanocomposites with enhanced properties was confirmed using a range of characterization techniques, photocatalysis and photoelectrochemical studies. Compared to the pristine ZnO nanoparticles, the Ag@ZnO nanocomposites exhibited enhanced visible light photocatalytic activity for the degradation of methylene blue and photoelectrochemical response. A mechanism was proposed to account for the photocatalytic activities of the Ag@ZnO nanocomposite that showed the surface plasmon resonance (SPR) of Ag is an effective way of enhancing the visible light photocatalytic activities.
Refractory Plasmonics, Urcan Guler, Alexandra Boltasseva, Vladimir M. Shalaev
Refractory Plasmonics, Urcan Guler, Alexandra Boltasseva, Vladimir M. Shalaev
U. Guler
Refractory materials are defined as those with a high melting point and chemical stability at temperatures above 2000°C. Applications based on refractory materials, usually nonmetallic, span a wide range of areas including industrial furnaces, space shuttle shields, and semiconductor technology. Metals have also been studied as refractories; however, the optical properties of those metals that have been tried for high-temperature applications were not good enough to be used in plasmonic applications (these are almost entirely based on noble metals, which are not good refractories). Refractory materials that exhibit reasonably good plasmonic behavior would undoubtedly enable new devices and boost such …
Biogenic Fabrication Of Au@Ceo2 Nanocomposite With Enhanced Visible Light Activity, Mohammad Mansoob Khan Dr, S. A. Ansari, M. O. Ansari, B. K. Min, J Lee, M. H. Cho
Biogenic Fabrication Of Au@Ceo2 Nanocomposite With Enhanced Visible Light Activity, Mohammad Mansoob Khan Dr, S. A. Ansari, M. O. Ansari, B. K. Min, J Lee, M. H. Cho
Dr. Mohammad Mansoob Khan
This study reports a biogenic approach to the synthesis of Au@CeO2 nanocomposite using electrochemically active biofilms (EABs) in water under normal pressure and 30 °C. This work presents the results of extensive morphological, structural, optical, visible light photoelectrochemical and photocatalytic studies of Au@CeO2 nanocomposite. The presence of a large number of interfaces between Au nanoparticles and CeO2 for charge transfer is believed to play a key role in enhancing the optical and visible light photoelectrochemical and photocatalytic performance of Au@CeO2 nanocomposite. The enhanced visible light degradation of methyl orange and methylene blue by Au@CeO2 nanocomposite was much higher than that …
Ptsa Doped Conducting Graphene/Polyaniline Nanocomposite Fibers: Thermoelectric Behavior And Electrode Analysis, Mohammad Mansoob Khan Dr, M. O. Ansari, S. A. Ansari, M. I. Amal, J Lee, M. H. Cho
Ptsa Doped Conducting Graphene/Polyaniline Nanocomposite Fibers: Thermoelectric Behavior And Electrode Analysis, Mohammad Mansoob Khan Dr, M. O. Ansari, S. A. Ansari, M. I. Amal, J Lee, M. H. Cho
Dr. Mohammad Mansoob Khan
Highly conducting graphene/polyaniline (GN@Pani) nanocomposite was prepared by the in-situ oxidative polymerization of aniline in the presence of GN and the surfactant, cetyltrimethylammonium bromide (CTAB). The micellar structure of CTAB assisted both, the formation of GN@Pani tubules and the dispersion of GN. Sheet-like GN was distributed uniformly in the Pani matrix, leading to high electrical conductivity because of the π-π interactions between Pani and GN. Studies of the thermoelectrical behavior using isothermal and cyclic aging techniques showed that GN@Pani possessed a high combination of electrical conductivity and thermal stability, even beyond 150°C. GN@Pani was used as cathode active material in …
Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Hideyo Takatsuki, Madhukar Kolli, Kevin Rice, B. Day, Shinichi Asano, Mashiur Rahman, Yue Zhang, Ryoki Ishikawa, Kazuhiro Kohama, Eric Blough
Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Hideyo Takatsuki, Madhukar Kolli, Kevin Rice, B. Day, Shinichi Asano, Mashiur Rahman, Yue Zhang, Ryoki Ishikawa, Kazuhiro Kohama, Eric Blough
B. Scott Day
The study of biomolecular motors represents a rapidly and progressing field of nanobiotechnology. Here, we present a simple method for patterning myosin II on a microstructured surface. Our findings indicate that UV/ozone treatment can be used to alter the hydrophobicity of trimethyl-chloro-silane (TMCS) coated glass surfaces, to alter protein binding, and effectively produce localized motor activity. Taken together, these data suggest that photoreactive patterning may be useful for the selective localization of functional myosin II motor tracks.
Modeling, Analysis, And Experimental Validation Of A Bifurcation-Based Microsensor, Vijay Kumar, Yushi Yang, J. William Boley, Geroge Chiu, Jeff Rhoads
Modeling, Analysis, And Experimental Validation Of A Bifurcation-Based Microsensor, Vijay Kumar, Yushi Yang, J. William Boley, Geroge Chiu, Jeff Rhoads
Geroge T.-C. Chiu
The potential to detect very small amounts of added mass has driven research in chemical and biological sensors based on resonant micro-and nanoelectromechanical systems over the past two decades. While traditional resonant mass sensors utilize chemomechanically induced shifts in linear natural frequency for mass detection, alternate sensing approaches which exploit near-resonant nonlinear behaviors have garnered interest from the research community due to their potential to yield improved sensor metrics and to simplify final device implementations. This paper investigates the development of an amplitude-based mass sensing approach which utilizes the dynamic transitions that occur near a cyclic-fold/saddle-node bifurcation in the nonlinear …
Bifurcation-Based Mass Sensing Using Piezoelectrically-Actuated Microcantilevers, Vijay Kumar, J. William Boley, Yushi Yang, Hendrik Ekowaluyo, Jacob K. Miller, George T.C. Chiu, Jeff F. Rhoads
Bifurcation-Based Mass Sensing Using Piezoelectrically-Actuated Microcantilevers, Vijay Kumar, J. William Boley, Yushi Yang, Hendrik Ekowaluyo, Jacob K. Miller, George T.C. Chiu, Jeff F. Rhoads
Geroge T.-C. Chiu
In conventional implementations, resonant chemical and biological sensors exploit chemomechanically-induced frequency shifts, which occur in linear systems, for analyte detection. In this letter, an alternative sensing approach, based upon dynamic transitions across saddle-node bifurcations is investigated. This technique not only has the potential to render improved sensor metrics but also to eliminate frequency tracking components from final device implementations. The present work details proof-of-concept experiments on bifurcation-based sensing, which were conducted using selectively functionalized, piezoelectrically-actuated microcantilevers. Preliminary results reveal the proposed sensing technique to be a viable alternative to existing resonant sensing methods. (C) 2011 American Institute of Physics. [doi:10.1063/1.3574920]
Electrochemical And Metal-Phase Processes Accompanying Hydrogen Absorption In Aluminum During Aqueous Corrosion, Kurt R. Hebert, Ömer Ö. Çapraz, Pranav Shrotriya, Guiping Zhang
Electrochemical And Metal-Phase Processes Accompanying Hydrogen Absorption In Aluminum During Aqueous Corrosion, Kurt R. Hebert, Ömer Ö. Çapraz, Pranav Shrotriya, Guiping Zhang
Ömer Özgür Çapraz
Alkaline corrosion of aluminum results in large supersaturations of hydrogen, and formation of hydride and subsurface voids.1-4 Aluminum itself is not susceptible to stress corrosion cracking (SCC), but hydrogen and hydride effects are significant for SCC mechanisms on Al and Mg alloys. Chu found evidence that corrosion-induced tensile stress in several alloys additively combines with external tensile stress to promote SCC, and attributed the former to lattice contraction associated with vacancies injected during corrosion.5 Evidence for vacancy injection on Al was found from X-ray diffraction and in situ curvature measurements on Al thin films undergoing corrosion.1,6 Here we report new …
Mixed Culture Electrochemically Active Biofilms And Their Microscopic And Spectroelectrochemical Studies, Mohammad Mansoob Khan Dr, S. A. Ansari, J. H. Lee, J. Lee, M. H. Cho
Mixed Culture Electrochemically Active Biofilms And Their Microscopic And Spectroelectrochemical Studies, Mohammad Mansoob Khan Dr, S. A. Ansari, J. H. Lee, J. Lee, M. H. Cho
Dr. Mohammad Mansoob Khan
Mixed culture electrochemically active biofilms (EABs) were developed on carbon paper using a sludge with mixed culture bacteria for microscopic and pectroelectrochemical studies because a naturally mixed culture bacterial strain is more applicable than a pure culture strain. EAB development was confirmed by microbial fuel cells (MFCs) by obtaining a constant increase in potential (∼0.36 V). Microscopic and spectroscopic studies showed that a mixed culture EABs formed on the support. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, indicated that the EABs could be source of electrons and used effectively for …
Modeling The High-Speed Switching Of Far-Infrared Radiation By Photoionization In A Semiconductor, Thomas E. Wilson
Modeling The High-Speed Switching Of Far-Infrared Radiation By Photoionization In A Semiconductor, Thomas E. Wilson
Thomas E. Wilson
Data from an earlier study [T. Vogel et al., Appl. Opt. 31, 329 (1992)] on the subnanosecond switching of 119-μm radiation in high-resistivity silicon by pulsed UV laser radiation, is compared with a refined one-dimensional numerical multilayer model accounting for the generation, recombination, and diffusion of the free carriers on the resulting far-infrared optical properties of the silicon. The inclusion of recent measurements for carrier-density and temperature-dependent transport parameters leads to improved agreement between experiment and theory.
Accessibility Of Home Blood Pressure Monitors For Blind And Visually Impaired People, Mark M. Uslan, Darren M. Burton, Thomas E. Wilson, Steven Taylor, Bruce S. Chertow, Jack E. Terry
Accessibility Of Home Blood Pressure Monitors For Blind And Visually Impaired People, Mark M. Uslan, Darren M. Burton, Thomas E. Wilson, Steven Taylor, Bruce S. Chertow, Jack E. Terry
Thomas E. Wilson
Background: The prevalence of hypertension comorbid with diabetes is a significant health care issue. Use of the home blood pressure monitor (HBPM) for aiding in the control of hypertension is noteworthy because of benefits that accrue from following a home measurement regimen. To be usable by blind and visually impaired patients, HBPMs must have speech output to convey all screen information, an easily readable visual display, identifiable controls that are easy to use, and an accessible user manual. Methods: Data on the physical aspects and the features and functions of nine Food and Drug Administration-approved HBPMs (eight of which were …
Superlattice Ultrasonic Generation, Thomas E. Wilson, M. Oehme, E. Kasper, H-J. L. Gossmann
Superlattice Ultrasonic Generation, Thomas E. Wilson, M. Oehme, E. Kasper, H-J. L. Gossmann
Thomas E. Wilson
We report the first experimental evidence for the resonant excitation of coherent high-frequency acoustic phonons in semiconducting doping superstructures by far-infrared laser radiation. After a grating-coupled delta-doped silicon doping superlattice is illuminated with ~1 kW/mm2 nanosecond-pulsed 246 GHz laser radiation, a delayed nanosecond pulse is detected by a superconducting bolometer at a time corresponding to the appropriate time-of-flight for ballistic longitudinal acoustic phonons across the (100) silicon substrate. The absorbed phonon power density in the microbolometer is observed to be ~10 μW/mm2, in agreement with theory. The phonon pulse duration also matches the laser pulse duration. The absence of any …
Progress On: “Coherent Terahertz Acoustic Phonon Scattering: Novel Diagnostic For Erosion In Plasma Thruster Discharge Chamber Walls", Thomas E. Wilson, Iain D. Boyd
Progress On: “Coherent Terahertz Acoustic Phonon Scattering: Novel Diagnostic For Erosion In Plasma Thruster Discharge Chamber Walls", Thomas E. Wilson, Iain D. Boyd
Thomas E. Wilson
The study is based on the success in obtaining the first experimental evidence for the direct excitation of coherent nanosecond-pulsed high-frequency acoustic phonons in semiconducting doping superstructures by electromagnetic fields of the same frequency. Acoustic phonons are detected by a superconducting bolometer, with nanosecond resolution, at the appropriate time-of-flight across a (100) silicon substrate for ballistic longitudinal phonons when a silicon delta-doped doping superlattice is illuminated with grating-coupled nanosecond-pulsed 246-GHz laser radiation with an approximate power density of 1 kW/mm2. The absorbed phonon power density in the bolometer detector is estimated to be 10 μW/mm2, in agreement with theory. The …
Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson
Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson
Thomas E. Wilson
We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using imagereversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. [1], and direct nanosecond-pulsed photoexcitation to obtain the microbolometer’s characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution …
Highly Photoactive Sno2 Nanostructures Engineered By Electrochemically Active Biofilm, S. A. Ansari, Mohammad Mansoob Khan Dr, M. O. Ansari, J. Lee, M. H. Cho
Highly Photoactive Sno2 Nanostructures Engineered By Electrochemically Active Biofilm, S. A. Ansari, Mohammad Mansoob Khan Dr, M. O. Ansari, J. Lee, M. H. Cho
Dr. Mohammad Mansoob Khan
This paper reports the defect-induced band gap narrowing of pure SnO2 nanostructures (p-SnO2) using an electrochemically active biofilm (EAB). The proposed approach is biogenic, simple and green. Systematic characterization of the modified SnO2 nanostructures (m-SnO2) revealed EAB-mediated defects in pure SnO2 nanostructures (p-SnO2). m-SnO2 nanostructures in visible light showed the enhanced photocatalytic degradation of p-nitrophenol and methylene blue compared to p-SnO2 nanostructures. Photoelectrochemical studies, such as electrochemical impedance spectroscopy and linear scan voltammetry, also revealed a significant increase in the visible light response of m-SnO2 compared to p-SnO2 nanostructures. The enhanced activities of m-SnO2 in visible light was attributed to …