bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Bending and Mechanical Buckling Instabilities in Electrospinning Jets
Authors: Reneker Darrell H. , Han Tao 
Published: April 2011

ABSTRACTThe determination of the behavior of the jet path in the vicinity of the onset of the primary electrical bending instability is important for the orderly collection of the nanofibers produced by electrospinning. A stable jet was observed with a high frame rate, short exposure time video camera. The collection process was complicated but predictable within limits, so the design and creation of some two or three dimensional structures of nanofibers is feasible, if the considerations described below are incorporated into the design and production processes.The fluid jet in the straight segment of the path, and the more solid nanofibers in the coils of the primary electrical bending instability were collected on stationary and moving surfaces. The diameter and characteristic path of the jet depended on the exact distance between the orifice and the collector, if other parameters were not changed. The moving surfaces caused the various coils that were collected to be displaced rather than superimposed. The fiber collected on the moving surfaces preserved a record of the electrical and mechanical instabilities that occurred. If the straight segment was very fluid, the jet formed a series of small sessile drops on the collector, but when the jet was more solid, buckling occurred and produced small, complicated loops close to point at which the jet hit the surface. Buckling was observed during collection of the straight segment and the first coils of the electrically driven electrical bending instability. A moving inclined collector was used to collect the fibers. Surface velocities were up to about 5 meters per second. These velocities are commensurate with the velocities at which the solidifying jet approached the surface. A variety of structures of loops, both conglutinated and not, associated with the instabilities were created.The jets used in this work were formed from solutions of polyethylene oxide, nylon-6, poly lactic acid, and other polymers. Several solvents were used for some of the polymers, and details of the jet path changed when the solvent or the concentration changed. The jets issued from a pendent drop on a glass capillary with an orifice diameter of about 160 microns. A potential difference in the range of 500 to 13,000 volts was applied between the orifice and the collector. The distance from the orifice to the grounded collector varied from 1 mm to 30 cm. Interference colors associated with jet diameters around 10 microns were observed in the straight segment. The color patterns were stable, indicating that the process variations were small.
Development of Novel Materials for Proton Exchange Membrane Fuel Cells
Authors: Birkan Burak , Levi Albert , Gümeci Cenk , Gülgün Mehmet Ali , Mencelo∂u Yusuf Ziya 
Published: April 2011

ABSTRACTThe most known utilization of catalysts is the use of metal nanoparticles on the electrode of a Proton Exchange Membrane Fuel Cell on which the electrode consists of catalyst, either Pt or Pd on a carbon support. In this research porous polyacrylonitrile (PAN) based carbon nanofibers comprising nanosized metal particles are produced using electrospinning technique. By the optimization of polymer chemistry, electrospinning variables and carbonization procedures the effective metal size is reduced up to 5 nm. It is still possible to enhance the catalytic performance by decreasing the metal concentration and/or enable using less catalytic material for equivalent catalytic performance which can lead to cost savings, amongst other advantages.
Ferroelectric Polymers with Chemically Tunable Dielectric Constants
Authors: Lu Yingying , Claude Jason , Li Kun , Zhang Qiming , Wang Qing 
Published: April 2011

ABSTRACTWe present a modular approach toward poly(vinylidene fluoride) based ferroelectric polymers with high dielectric constants and energy densities. This strategy is based on a two-step reaction including the co-polymerization of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE) and a subsequent hydrogenation reaction. Due to the similar reactivity of VDF and CTFE in free radical polymerization and quantitative yield of dechlorination reaction, the chemical compositions of the resulting terpolymers can be precisely controlled, leading to tunable Curie temperatures and dielectric constants. A library of the ferroelectric polymers with dielectric constants varying from 11 to 50 measured at 1 kHz and room temperature has been prepared. The structural characteristics including microstructure, chain conformation, and crystallinity of the polymers have been carefully elucidated as a function of the chemical composition by 1H and 19F NMR, Fourier transform infrared spectroscopy, and wide angle X-ray diffraction. The influence of the polymer compositions on thermal transitions and dielectric constants has also been investigated.
Dielectric Properties of CaCu3Ti4O12-P(VDF-TrFE) Composite
Authors: Shan Xiaobing , Yang Xin , Zhang Kewei , Cheng Zhongyang 
Published: April 2011

ABSTRACTBy using conventional solution casting method, a flexible ceramic [CaCu3Ti4O12 (CCTO)]-Polymer [P(VDF-TrFE)] composite has been fabricated. The CCTO ceramic powders with a relative uniform size were prepared by traditional powder processing method. The dielectric properties of these films with different CCTO fractions were determined. The process was optimized to achieve high dielectric constant. A dielectric constant about 510 at room temperature and 1240 at 95 °C at 1 kHz for 6 layer hot compression was obtained.
Preparation and Surface Modification of Rare-Earth Doped Ceramic Nano-Phosphors for Fluorescence Bioimaging
Authors: Soga Kohei , Saito Yu , Shimizu Kazuaki , Nagata Hiroyasu , Konishi Tomoya , Nagasaki Yukio 
Published: April 2011

ABSTRACTRare-earth doped yttrium oxide nano-particles modified with bio functional polymers are one of the good candidate for upconversion bio imager. The requirement to the particles for bio imaging application is a small particle size less than 50 nm, dispersion and chemical durability in body fluid. In this study, polyacrylic acid (PAAc) was used for both precursor precipitation and surface modification of the calcinated particles. The use of the PAAc resulted in small particle size at 33 nm. Also, the modification by adding 104 PAAc/particle resulted in chemical durability and dispersion of the particles under heavily acidic and basic conditions.
Graph Spectra of Carbon Nanotube Networks: Molecular Communication
Authors: Bush Stephen Francis , Li Yun 
Published: April 2011

ABSTRACTThe integrated application within random carbon nanotube networks (CNT) to carry and fuse information, as well as perform simple sensing, is explored. One may imagine small CNT networks with functionalized nanotubes simultaneously sensing multiple targets in-vivo for unprecedented understanding of biological pathways. This is clearly distinct from the traditional convoluted approach of using CNT networks to construct transistors that are in turn used to construct communication networks. With random CNT network layouts, routing of information is an integral part of the physical layer.A Mathematica analysis for evaluating random CNT networks has been developed and used to verify design characteristics. The graph spectrum of the CNT network is used to determine resistance and electron mobility characteristics. Thus, we have been able to find relationships among CNT network structure and electron mobility. The nanotube density allows for an increase in the number of bits per square meter of information transfer compared to wireless communication. Consider a wireless network; a typical bit-meters/second capacity is limited in a traditional wireless network. The maximum wireless capacity approximation in a wireless broadcast media is contrasted with a CNT network; we look at the efficiency of CNT networks to carry information and compare with theoretical limits.
DAPI Method: A Novel Assay to Evaluate the In vitro Impact of Nanomaterials on Mammalian Cells
Authors: Raja Pavan M. V. , Connolley Jennifer , Ajayan Pulickel M. , Nalamasu Omkaram , Thompson Deanna M. 
Published: April 2011

ABSTRACTThe increasing importance of nanomaterial-related applications has given rise to concerns pertaining to their impact on human health. In vitro mammalian cell-based assays can provide a quick and simple estimate of the possible adverse effects of the nanomaterials. However, recent studies have questioned the efficacy of traditional assays such as the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, in evaluating cell-nanomaterial interactions, implying the need for alternate methods. We applied image analysis to enumerate the DAPI (2-[4-(Aminomethyl) phenyl]-1H-indole-6-carboximidamide, dihydrochloride) – stained cellular nuclei. Image analysis, being non-destructive, capable of automation, and applicable over a wide range of cell seeding densities, offers several advantages compared to older methods like the MTT assay and hemocytometry. Using image analysis, the impact of singlewalled carbon nanotubes (SWNT) on rat aortic smooth muscle cell (SMC) growth kinetics, were examined. Despite the carbon nanomaterial presence, the fluorescent signal from the nuclei was not noticeably impacted over the SWNT range examined (0.00-0.10 mg/ml). We anticipate that this method can also be applied to evaluate the biological impact of other nanomaterials.
Development of Au Nanowires for Recording Electrical Activity in Neural Cells
Authors: Silverberg Jesse , Saha Sucharita , O'Malley Donald , Menon Latika 
Published: April 2011

ABSTRACTThe application of gold nanowire arrays for neuronal recording and stimulation is explored. The process of electrochemical anodization is utilized to grow an aluminum oxide template consisting of an array of closely packed cylindrical pores with diameters in the range of nanometers and micron scale depth. The method of electrodeposition is used to deposit gold within the pores forming a nanowire array. By means of micro and nanoscale fabrication processes, this array is integrated at one end with microscale gold electrodes. At the other end, neuron cells are cultured. Such nanowire-array structures will eventually be used to record and stimulate neuronal activity.
Enhanced thermal Properties and Gas Barrier Property of PMMA Nanocomposites with Layered Silicate via Soap-Free Emulsion Polymerization
Authors: Cheng Hsiu-Yu , Jang Guang-Way William 
Published: April 2011

ABSTRACTPolymer/SWN nanocomposites were synthesized in the soap-free emulsion polymerization of methyl methacrylate (MMA) using 2-hydroxylethyl methacrylate (HEMA). The SWN in the polymer/SWN nanocomposites was individually dispersed in water, and these are adsorbed on the surface of monomer droplets. Polymer/SWN nanocomposites were obtained by adding an aqueous dispersion of layered silicate to the polymer emulsion. X-ray diffraction (XRD) and FT-IR spectra were utilized to characterize the structures of the nanocomposites. The degree of dispersion of these nanocomposites was investigated by transmission electron microscopy (TEM). Furthermore, the thermal and mechanical properties of polymer/SWN nanocomposites were determined using thermogravimetric analysis (TGA), differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA). The increased tanδ of the obtained nanocomposites is caused by the fine dispersion of SWN particles into the polymer matri
A Self-Contained, Nano-Gap Biomolecule Impedance Sensor with Fluidic Control System
Authors: Liang Huinan , Nam Wook Jun , Fonash Stephen J 
Published: April 2011

ABSTRACTA sub-50 nm biomolecular direct electrical-detection structure integrated with micro- and nano-fluidic systems has been constructed. These devices are composed of integrated microfluidic channels in PDMS and nanofluidic channels in silicon oxide. These in turn are all integrated with a nano-gap sensing structure which has metallic electrodes. The microfluidic channel in PDMS provides access to the nanofluidic channel feeding the nano-gap sensing structure. We provide a demonstration of the bio-molecular sensing capabilities of our device by using the carboxyl-amino group interaction and a nano-gap structure with gold electrodes. First, probe molecules with amino groups are infused through the fluidic system to the nano-gap and are self-assembled onto the gold electrodes via thiolate bonding. Then target molecules with terminating carboxyl groups are infused to bind with the probe molecules. Impedance changes are measured electrically at each infusing and binding step using an Agilent 4284A impedance analyzer thereby detecting the appearance of each molecule type as it passes through the system. We are able to detect about 15% impedance changes with the carboxyl-amino binding occurrence.
Development of Double-cantilever Infrared Focal Plane Arrays: Fabrication and Post-process Curvature Modification
Authors: Huang Shusen , Lin I-Kuan , Tao Hu , Zhang Xin 
Published: April 2011

ABSTRACTUncooled double-cantilever microbolometers have the potential of reaching a noise-equivalent temperature difference (NETD) approaching the theoretical limit and thus have gained increasing interest. Each pixel of the device consists of two overlapping bimaterial cantilevers that deflect in opposite directions as their temperature rises due to the absorption of incident infrared radiation. This paper reports recent progress in the development of these double-cantilever focal plane arrays (FPAs), including fabrication and post-process curvature modification.
Nanopatterned Hydrogel Probes for Rapid Detection of Staphylococcus aureus
Authors: Saaem Ishtiaq , Kreiswirth Barry , Libera Matthew 
Published: April 2011

ABSTRACTWe studied the use of nanopatterned hydrogels as a possible foundation for medical devices for the detection ofStaphylococcus Aureus. Nanopatterned hydrogels, approximately 200 nm in diameter, were created by locally crosslinking dry amine-terminated poly(ethylene glycol) [PEG] (6000 Da) thin films using a focused electron beam. These gels then had a dry height of 50 nm and a swell ratio of about five. They were patterned into arrays with approximately 500 nm inter-gel spacing. These arrayed gels were functionalized with Immunoglobulin G [IgG], a biomolecule that binds Protein A. We are interested in seeing whether these arrayed gels can be used for bacterial capture and subsequent detection. We show, using an assay that binds IgG to Protein A expressingStaphylococcus Aureus[S.Aureus], that nanopatterned hydrogels can indeed be used as probes for detection. We further show that the specificity of our assay by using a knockout variant ofS.Aureusthat doesn't express Protein A as a negative control.
Properties of Ferromagnetic GaGdN
Authors: Hite J. K. , Davies R. P. , Frazier R. M. , Thaler G. T. , Abernathy C. R. , Pearton S. J. , Zavada J. M. 
Published: April 2011

ABSTRACTSingle phase GaGdN and GaGdN:Si films were grown on sapphire substrates. The undoped films were highly resistive films but became conductive with the addition of Si. SQUID magnetometry indicated room temperature ferromagnetism in both types of materials. Structural defects had a strong influence on the magnetic ordering of the material, as seen in a drastic reduction of magnetic moment with degrading crystalline quality. Magnetization of the co-doped film increased with Si content, reaching levels higher than that of the undoped material. Gd-doped AlN films grown in a similar fashion also displayed Curie temperatures above room temperature.
Growth and characterization of semi-polar (11-22) GaN with in-situ SiNx interlayers
Authors: Hollander Jonathan , McAleese Clifford , Kappers Menno , Humphreys Colin 
Published: April 2011

ABSTRACTSemi-polar (1122) GaN films were grown on (1100) m-plane sapphire substrates. Growth demonstrated surface striations aligned perpendicular to the in-plane GaN m-axis. SiNx interlayers were incorporated into the as-grown films with the purpose of decreasing the density of defects in the material. Inclusion of interlayers increased the characteristic length of surface striations and feature size. X-ray rocking curves widths are shown to be correlated to specific threading dislocation geometry. Skew-symmetric omega scan peak broadening suggests a decrease in the proportion of screw-type dislocations to edge-type dislocations with increasing number of interlayers.
Titanium Nitride Epitaxy on Tungsten (100) by Sublimation Crystal Growth
Authors: Mercurio Lisa , Edgar James H. , Du Li , Kenik E. A. 
Published: April 2011

ABSTRACTTitanium nitride crystals were grown from titanium nitride powder on tungsten by the sublimation-recondensation technique. The bright golden TiN crystals displayed a variety of shapes including cubes, truncated tetrahedrons, truncated octahedrons, and tetrahedrons bounded by (111) and (100) crystal planes. The TiN crystals formed regular, repeated patterns within individual W grains that suggested epitaxy. X-ray diffraction and electron backscattering diffraction revealed that the tungsten foil was highly textured with a preferred foil normal of (100) and confirmed that the TiN particles deposited epitaxially with the orientation TiN(100)‖W(100) and TiN[100]‖W[110], that is, the unit cells of the TiN crystals were rotated 45° with respect to the tungsten. Because of its larger coefficient of thermal expansion compared to W, upon cooling from the growth temperature, the TiN crystals were under in-plane tensile strain, causing many of the TiN crystals to crack.
The Structural and Optical Properties of Self-assembled InGaN/GaN Quantum Dots Grown by Molecular Beam Epitaxy
Authors: Smeeton Tim Michael , Sénès Mathieu , Smith Katherine L , Hooper Stewart E , Heffernan Jon 
Published: April 2011

ABSTRACTThe structural and optical properties of InGaN quantum dots grown by plasma-assisted molecular beam epitaxy (MBE) have been characterised using atomic force microscopy, high-resolution transmission electron microscopy (TEM), Z-contrast scanning TEM, micro-photoluminescence (PL), temperature dependent PL and time-resolved PL. The uncapped InGaN nano-islands have densities of ∼1.5 × 1011 cm−2, heights of (1.7 ± 1.0) nm and diameters of (10 ± 4) nm. These parameters are not substantially changed during overgrowth of a GaN cap and the resulting quantum dots have a composition of In0.15Ga0.85N. The observation of narrow luminescence peaks in micro-PL measurements proves light emission from discrete energy states and the optical properties indicate strong confinement of carriers in the quantum dots and an unusually weak impact of piezoelectric field effects.
Electronic Properties and Stability of Artificial In-N Molecules
Authors: Pozhar Liudmila A , Mitchel William C 
Published: April 2011

ABSTRACTIn the work reported here the Hartree-Fock (HF), restricted open shell HF (ROHF), and multiconfiguration self-consistent field (CI/CASSCF/MCSCF) methods are used to predict electronic properties of several artificial molecules of InAsN and indium nitride whose structure and composition have been derived from those of the corresponding symmetry elements of the zincblende and wurtzite bulk lattices. Both quantum-confined and “vacuum” clusters (whose geometry has been optimized without any spatial constraints applied to the atomic positions) were studied focusing on the electronic energy level structure, direct optical transition energy (OTE), and charge and spin distributions. The obtained results indicate that inclusion of “impurity” atoms (such as As atoms) may enhance stability of both vacuum and confined pyramidal In-N molecules and provide for manipulations of the OTE in a wide range of its values. The CI/CASSCF/MCSCF OTEs of the studied wurtzite-based clusters may also vary in a wide range, from 1.7440 eV for the smallest pre-designed prismatic molecule In6N6 to 6.9780 eV for its almost perfect prismatic “vacuum” counterpart. These evaluations closely correlate with experimental data available in literature.
Design and Optimization of GaN-based Semiconductor Saturable Absorber Mirror Operating at Around 415 nm
Authors: Lin Fen , Xiang Ning , Wang Xin Cai , Arokiaraj Jesudoss , Liu Wei , Liu Hong Fei , Chua Soo Jin 
Published: April 2011

ABSTRACTA broadband GaN-based semiconductor saturable absorber mirror (SESAM) with a dielectric SiO2/Si3N4 distributed Bragg reflector (DBR) operating at wavelength around 415 nm was fabricated. Serious oscillation fringes due to the light interference were observed in the SESAM's reflectance spectrum. Such oscillation in reflectivity can impede the function of the saturable absorber. Simulations showed that by removing the sapphire substrate and thinning the GaN buffer layer, oscillation fringes could be significantly reduced. Experiments were carried out and the results agreed well with the simulation prediction.
Ultrathin AlN/GaN Heterojunctions by MBE for THz Applications
Authors: Cao Yu , Jena Debdeep 
Published: April 2011

ABSTRACTHigh electron mobility transistor (NEMT) based on AlN/GaN can be the source to generate terahertz (THz) radiation. The basic requirements are that a) the electron density in the 2DEG should be large enough for ensuring that the electron-electron scattering mean-free path is much shorter than the distance between the contacts to ensure a viscous, fluid-like flow, and b) the mobility should be high enough such that the possible plasma modes are not strongly damped. To show AlN/GaN HEMT is a qualified candidate for THz generation, we have calculated the plasma frequency for the two-dimensional electron gas (2DEG) in the GaN channel and compared it with other material, such as Si, GaAs and InAs. 3nm AlN has been grown on the GaN substrate by Nitrogen-source radio-frequency molecular-beam expitaxy (RFMBE). The growth temperature has been optimized and found to be 730C. Results from Hall measurement show the electron charge is ∼2.5*1013 cm−2 with the mobility of 530 cm2/Vs (room temperature) and 860 cm2/Vs (77K). A series AlN samples have been grown and studied by AFM, which shows the critical thickness of AlN on GaN is between 4nm and 5nm.
Electrical Detection of Deoxyribonucleic Acid Hybridization With AlGaN/GaN High Electron Mobility Transistors
Authors: Kang ByoungSam , Pearton S. J. , Chen J. J. , Ren F. , Johnson J. W. , Therrien R. J. , Rajagopal P. , Roberts J. C. , Piner E. L. , Linthicum K. J. 
Published: April 2011

ABSTRACTAu-gated AlGaN/GaN High Electron Mobility Transistor (HEMT) structures were functionalized in the gate region with label free 3′-thiol modified oligonucleotides. This serves as a binding layer to the AlGaN surface for hybridization of matched target Deoxyribonucleic Acid (DNA). X-ray photoelectron spectroscopy (XPS) shows that immobilization of thiol modified DNA covalently bonded with gold on the gated region. Hybridization between probe DNA and matched or mismatched target DNA on the Au-gated HEMT was detected by electrical measurements. The HEMT drain-source current showed a clear decrease of 115 μA as this matched target DNA was introduced to the probe DNA on the surface, showing the promise of the DNA sequence detection approach for biological sensing.