bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemo-electrical energy conversion of Adenosine triphosphate in a Biological Ion Transporter
Authors: Sundaresan Vishnu Baba , Sarles Stephen Andrew , Goode Brian J , Leo Donald J 
Published: April 2011

ABSTRACTIon transport across cell membranes happens through protein channels and pumps expending concentration gradients, electrical gradients and energy from chemical reactions. Ion exchange in cell membranes is responsible for nutrient transport from production sites to where they are broken down to release energy. Sucrose transport is vital for growth in higher plants and recent research has led to the discovery of a class of sugar carriers called SUT4. The SUT4 transporter is a low affinity, high capacity proton-sucrose transporter that participates in long distance sucrose transport in higher plants. We demonstrated the possibility to use purified SUT4 transporter proteins — with the genetic code from Arabidopsis thaliana expressed on yeast cells — for fluid transport driven by pH gradient and from exergonic ATP hydrolysis reaction in the presence of ATP-ase enzyme. The SUT4 proteins were reconstituted on a planar bilayer lipid membrane formed from 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine (POPE) phospholipids on a porous substrate. This article builds upon our previous work to harness energy from the ATP-ase reaction using SUT4 to produce a proton current through SUT4 and demonstrates the technical feasibility to generate electrical current in an external circuit. The results from our characterization experiments on a single cell demonstrate that the power source behaves like a constant current power source with an internal resistance of 10-22 kΩ and produces a peak power of 150 nW.
Nanocomposite with Very Large Electro-optic Effect and Widely Tunable Refractive Index
Authors: Chen Qin , Lin Minren , Lee Jonathan E , Zhang Qiming , Yin Shizhuo 
Published: April 2011

ABSTRACTVery large electro-optic effect has been observed in relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) ( P(VDF-TrFE-CFE) ) terpolymer. By adding small amount of zinc sulfide (ZnS) nanoparticles, the refractive index of the nanocomposites can be tuned between about 1.4 and 1.5 while retaining large electro-optic effect and high transparency. Tunable long-period fiber gratings have been fabricated with the nanocomposite as the second cladding, and over 50nm of resonant wavelength shift has been achieved under a change of electric field of 30V/μm, which is much larger than other reported E-O tuning ranges. This corresponds to a pure refractive index change of the nanocomposite of Δn/n ∼ 0.4%.
A Study on Formation of Needle-like Polyanilines
Authors: Jung Woo-Hyuk , Kim Dong-Young , Lee Young-Moo , McCarthy Stephen P. 
Published: April 2011

ABSTRACTNeedle-like polyanilines (PANi) were prepared at 15 °C by emulsion polymerization and their conductivities were obtained up to 3 S/cm according to the addition rate of ammonium peroxysulfate (APS) aqueous solutions with reaction conditions of 0.4 to 0.5 APS/aniline ratios and 0.4 to 0.5 M aniline concentrations. Needle-like complexes doped with p-toluenesulfonic acid (pTSA) were prepared with the oxidant solution added so slowly as to be for 3 to 3.6 hours. The high reaction temperatures ranging from 5 to 15 °C was the second condition to have needle-like anilinium complexes polymerized without their breaking during polymerization. A filler shape is one of the most important parameters influencing a percolation concentration of conductive fillers dispersed in a non-conductive matrix. Needle-like polyanilines could be potentially used as conductive fillers to show electromagnetic interference and radar absorption effects.
Resonant Sensors for Microfluidic Applications
Authors: Niebelschütz Florentina , Tonisch Katja , Cimalla Volker , Brückner Klemens , Stephan Ralf , Hein Matthias , Schober Andreas , Ambacher Oliver 
Published: April 2011

ABSTRACTIn this work we present both resonators working at ambient conditions and their first application as a biological and physical sensor. Singly- and doubly-clamped resonators of different geometries were realized using active layers of silicon carbide and aluminum nitride. The resonators were excited by magneto-motive actuation. The quality factor reached 350 and 50000 in air and in vacuum (2-5 10−5 mbar), respectively, which is sufficient for sensing applications in air. The resonance shift caused by mass loadings in the range of picograms and by single biological cells was measured at ambient conditions. Initial non-resonant measurements in liquids such as propanol were performed to investigate the possibility of viscosity measurements in small volumes such as microfluidic channels and droplets.
Gas Sensor Based on the Network of SnO2 Semiconducting Nanowires
Authors: Choi Young-Jin , Hwang In-Sung , Choi Kyoung-Jin , Park Jae-Hwan , Park Jae-Gwan 
Published: April 2011

ABSTRACTA simple and efficient way of preparing highly sensitive SnO2 nanowire-based gas sensors without an arduous lithography process was studied. The network of SnO2 nanowires could be suspended upon the Si substrate by separating the Au catalyst layer from the substrate. As the electric current is transported along the networks of the nanowires, not along the bottom layer on the substrate, the sensitivity to gases was maximized in the suspended and networked structures. The sensitivities were 18 and 180 when the NO2 concentrations were 0.5 and 5 ppm. The response time was typically 20-50 s.
Fabrication of Nanostructured ZnO UV Sensor
Authors: Hullavarad Shiva S. , Hullavarad N. V. , Mooers M. , Karulkar P. C. 
Published: April 2011

ABSTRACTIn this paper we describe the fabrication of nanostructure based ZnO ultra violet sensor by a simple route without involving the clean room processing of inter digitized electrodes. The ZnO nanostructures consist of micro spheres of dimension 600 nm- 2 microns embedded in the network of nanowires of dimension 40 nm. The optical properties are studied by Photoluminescence spectroscopy that revealed the exciton band gap of 3.2 eV at 383 nm. The ultra violet sensors exhibit 2 orders of UV to visible rejection ratio. The photo response of Ultra violet sensors as a function of electrode spacing will be discussed.
Rapid Label-free Protein Detection Arrays on Coated Silicon Wafers
Authors: Striemer Christopher C. , Mace Charles R. , Miller Benjamin L. 
Published: April 2011

ABSTRACTWe are developing label-free Arrayed Imaging Reflectometry (AIR) for rapid and multiplexed protein detection. AIR is based on the high dynamic range in reflected optical intensity near a point of zero reflectance on an antireflection coated substrate. The reflectance is therefore highly sensitive to changes in film thickness, allowing direct detection of molecular binding when appropriate probe molecules are immobilized on the surface. The simplest implementation of AIR uses a 633 nm HeNe laser and a silicon wafer substrate coated with ∼1400 Å of SiO2. This system has a reflectance zero for s-polarized HeNe light incident at ∼70°. This interference film is then functionalized with probe molecules designed to bind to a specific target, and this binding can be detected with high sensitivity in the reflectance signal. By expanding the laser beam and collecting the reflected signal with a CCD camera, large arrays of detection spots can be imaged simultaneously. Spot intensity increases relative to the amount of target binding and the target solution concentration can then be calculated. We have demonstrated the detection of the Enteropathogenic E Coli membrane protein Intimin at levels below 10 pM using receptor molecule Tir as a probe, and are currently evaluating various clinical targets using more common antibody probes.
AAO Nanowells: Synthesis, in-situ Growth Study, and Applications in Ultra-sensitive Chemical Detection
Authors: Wang H. Hau , Son Kyung-In , Lee Byeongdu , Lu Jianjiang , Han Catherine 
Published: April 2011

ABSTRACTAnodized aluminum oxide (AAO) membranes consist of locally highly ordered nanopores. The pore diameter (20-200 nm) and pore-to-pore distance are controlled through the anodizing voltage and the choice of etching solution. High aspect ratio over 1,000 can easily be achieved which makes AAO membranes the ideal templates for making nanowires and nanotubes. In this work, the early stage of nanopore formation was studied in-situ with the use of small angle x-ray scattering (SAXS) and glazing incidence GISAXS techniques. The nanopores were found to grow as a function of the square root of growth time. The resulting short nanopores or nanowells with length below 200 nm were further characterized with use of SEM and AFM. These AAO nanowells showed interference color. Their reflectance UV-Vis spectra indicated strong angular dependence and can be understood with a simple single layer (nanoporous alumina over aluminum) model. These spectra are influenced by the nanowells thickness and diameter. Therefore, large array of interferometric AAO nanowells sensors are possible. When these nanowells are coated with Ag or Au thin films, in addition to enhanced interference color, highly sensitive surface enhanced Raman scattering (SERS) effect has been observed. These results will be presented.
Fabrication of Nanostructured Thin Films Using Porous Alumina Templates
Authors: Yin Aijun , Kim Jin Ho , Xu Jimmy 
Published: April 2011

ABSTRACTWe demonstrate a method for fabricating a variety of nanostructured metallic thin films by using one simple approach based on the use of anodic aluminum oxide (AAO) membrane as masking template. Highly-ordered large-area metallic nanopore- or nanotip-arrays (e.g., Ni, Ag, Au), with various sizes and shapes, were deposited onto AAO membranes through e-beam evaporation. Free standing nano-patterned metallic films were obtained after chemically removing the template and characterized using scanning electron microscopy and electrochemical methods. The nanostructured films will find use in a number of applications, such as plasmonics, electrochemical and biomedical analysis, and catalysis.
Physically Self-assembled Au Nanorod Arrays for SERS
Authors: Suzuki Motofumi , Nakajima Kaoru , Kimura Kenji , Fukuoka Takao , Mori Yasushige 
Published: April 2011

ABSTRACTWe have demonstrated surface-enhanced Raman spectroscopy on arrays of Au nanorods aligned in line by a dynamic oblique deposition technique. For the light polarized along the major axis of the nanorods, the plasma resonance of the Au nanorods has been tuned to a wavelength suitable for Raman spectroscopy. The Raman scattering on the discrete nanorods is enhanced significantly compared with that on semi continuous Au films. Since the preparation process is physically bottom-up, it is robust in its selection of the materials and is useful in providing the SERS sensors at low cost.
Plasma Surface Functionalization of Poly[bis(2,2,2-trifluoroethoxy)phosphazene]
Authors: Steely Lee B. , Allcock Harry R. , Kim Seong H. , Kim Jeong H. , Kang Bang-Kwon 
Published: April 2011

ABSTRACTPolyphosphazenes have a highly flexible backbone comprised of nitrogen and phosphorus atoms with two organic groups on each phosphorus. Materials in this class are inherently thermo-oxidatively stable, soluble, and chemically resistant especially when a variety of fluorinated organic groups are attached to the backbone. Several solution based side group exchange reactions have been examined previously that have profound effects on the surface topology, but may present problems for large scale production. We have utilized a high-throughput process for surface functionalization of polyphosphazenes to yield films with excellent chemical properties that can be tuned by surface treatment with plasma gases.Films of the poly[bis(2,2,2-trifluoroethoxy)phosphazene] were surface functionalized with plasmas of methane, oxygen, or nitrogen gases. An environmental plasma head was used to treat the spuncast films with free radicals in the treatment gases. These surface treatments were characterized by XPS and water contact angle methods to determine the modified surface structure of the films and the effect on surface properties. More than 90° changes in water contact angle are possible, depending on the plasma used and the density of surface functionalization. Tuning of the water contact angle was also possible from the native 101° static contact angle of poly[bis(2,2,2-trifluoroethoxy)phosphazene] to approximately 70°, 40°, or 4° with appropriate treatment using methane, nitrogen, or oxygen plasmas. Using XPS surface surveys we found that the fluorine concentration on the surface was higher than in the bulk material. Significant changes in the carbon, oxygen, and nitrogen 1s binding energies of the samples were also detected that varied with plasma treatment.This process allows polyphosphazene polymers or copolymers to be surface functionalized as an alternative to other processes where delamination or differences in thermal or chemical properties would preclude a traditional two polymer composite approach. Printing of controlled patterns with a cover mask are also possible to create a surface with several distinct regions of hydrophobicity or hydrophilicity or of functional groups all of which may be applicable in microfluidics, printing, adhesion, or sensor arrays.
Active Signal Processing: A Counter-intuitive Approach to Enhancing Signal-to-Noise Ratio via Noise Injection
Authors: George Thomas , Gulati Sandeep , Menahem Shahar Ben , Breaux James K , Boysen Cecilie , Daggumati Vijay , Quon Ronald 
Published: April 2011

ABSTRACTSince its origin in the early 1980s, the noise-injection based stochastic resonance technique has spearheaded a novel counter-intuitive approach toward improving sensor performance. Within this approach, named Active Signal Processing, instead of removing system noise by filtering (Passive Signal Processing), it is possible to improve signal-to-noise ratio (SNR) by injecting noise into the measurement. ViaLogy LLC. has pioneered the development and demonstration of Quantum Resonance Interferometry (QRI), a quantum stochastic resonance (QSR)-based technique for improving SNR. The core of QRI processing involves the QSR-based generation of a Quantum Expressor Function (QEF), which characterizes the system of interest by encoding within it the noise environment, minimum level of detection, and the precision of measurement. Using digital post-processing of sensor information, QRI can determine the presence of a signal by the destruction of the resonance condition responsible for generating the system QEF. For applications aimed at detecting the presence of a weak signal, the strength of the signal is proportional to the number of iterations of the algorithm required for destruction of the resonance; the fewer the iterations, the stronger the signal. The application of QRI for detecting the presence of weakly expressing genes in fluorescent DNA microarrays will be described.
NanoParticle Tracking Analysis; The Halo System
Authors: Malloy Andrew , Hole Patrick , Carr Bob 
Published: April 2011

ABSTRACTA new technique for nanoparticle sizing that allows visualisation of nanoscale particles in liquids on an individual basis is described. The technology comprises a metallised optical element illuminated by laser beam at the surface of which nanoscale particles in suspension can be directly visualised, sized and counted in real time using only a conventional optical microscope fitted with a low cost camera and a dedicated analytical software package.
Polyethylene Glycol Deposition Techniques for Antifouling Surfaces: Using Antistiction to Conserve Bioparticles for Recovery and Analysis
Authors: Chang Norine E. , Lean Meng H. , Limb Scott J. 
Published: April 2011

ABSTRACTFor bioparticle analysis within microfluidic devices, there is a risk of analytes adhering to surfaces, thereby compromising particle manipulation and recovery. To address this we have implemented polyethylene glycol (PEG)-type coatings by self-assembled monolayer (SAM) and plasma-polymerizing deposition techniques. Silane chemistry is used to deposit SAM films directly onto silicon dioxide surfaces, and in a special case for which a composite of metallic arrays and SiON within our MEMS device must be coated, an ultrathin layer of sputtered Si is added before the SAM protocol. We have also deposited PEG-like tetraglyme by plasma-polymerization onto substrates using an onsite-built reactor to provide antistiction treatment to all surfaces, including those that do not have chemical compatibility for the SAM technique. Three tests demonstrate the effectiveness of our surface treatments: static exposure to microbial suspensions, bioparticle transport across MEMS traveling-wave (TW) arrays, and bioparticle recovery from a circulating flow device. Our static microbial assays show significant reduction in B. thuringiensis adhesion to both the SAM and plasma-polymerized coatings and reduction in B. globigii adhesion to the plasma-polymerized coating. Our TW arrays, when coated with either the SAM or plasma-polymerized PEG film, are effective at reducing adhesion to polystyrene beads as well as both Bacillus species. Lastly, our bioparticle recovery, as gauged by spectrophotometry, improves by as much as one order of magnitude when we coat flow chambers with our plasma-polymerized film.
Spinodal Decomposition and Super-Paramagnetism in Dilute Magnetic Nitride Semiconductors
Authors: Sato Kazunori , Fukushima Tetsuya , Katayama-Yoshida Hiroshi 
Published: April 2011

ABSTRACTWe discuss origin of ferromagnetism in dilute magnetic semiconductors (DMS) and propose accurate calculation method for Curie temperature from first-principles. For more realistic materials design, we simulate inhomogeneous impurity distribution due to the spinodal decomposition in DMS from first-principles. Combining these techniques, we discuss super-paramagnetism and blocking phenomena in DMS and propose fabrication method of DMS with high blocking temperature.
Gadolinium and Oxygen co-doping of Gallium Nitride: an LSDA + U study
Authors: Lambrecht Walter R. L. , Larson Paul 
Published: April 2011

ABSTRACTResults of first-principles supercell calculations for Gd impurities, with and without O-impurities in the same cell are presented. The possibility of colossal magnetic moments, as reported by Dhar et al., [Phys. Rev. Lett. 94, 037205 (2005)] is discussed in view of the results. Particular attention is paid to the size of the conduction band spin splitting, induced by Gd. It is argued that O plays a more active role than merely providing the electrons leading to the magnetic moment. Estimates are made of the splitting of the conduction band required to explain the occurrence of colossal magnetic moments.
Fabrication of high-performance photodetector based on AlGaN/GaN hetero-field-effect transistors with p-GaN gate
Authors: Miura Shuichi , Fujii Takahiro , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu 
Published: April 2011

ABSTRACTAn AlGaN/GaN photo-hetero-field-effect transistor (photo-HFET) with a p-type GaN gate was fabricated and its properties were compared with those of a HFET without a p-type GaN layer. The photo-HFET with a p-GaN gate exhibited a high signal-to-noise ratio of five orders of magnitude and a dark current density of 10 nA/mm at a drain-source bias of 5 V. In contrast, when the photo-HFET was irradiated with 365 nm (490 μW/cm2) UV light, a photocurrent of over 1 mA/mm was achieved. The responsivity of the device was over 1 × 105 A/W.
Fabrication and Characterization of 2-inch diameter AlN Single-Crystal Wafers cut From Bulk Crystals
Authors: Bondokov Robert T. , Morgan Kenneth E. , Slack Glen A. , Schowalter Leo J. 
Published: April 2011

ABSTRACTAluminum nitride (AlN) boules larger than 2 inches in diameter were grown by the sublimation-recondensation technique. X-ray Laue diffraction was used to characterize the crystallinity and orientation of the boules, and 2” dia. substrates were sliced with typical thickness of ∼500 μm. The wafers were then polished in order to meet the common standards for wafer thickness and flatness. The Al-terminated surface was finished with a proprietary chemical-mechanical process and showed RMS roughness of 0.5 nm or less as measured by atomic force microscopy (5×5 μm area). Currently, the substrates have some polycrystalline regions that are highly textured but about 85% of the total area is monocrystalline. The dislocation density in the crystalline regions of the substrate was measured by preferential chemical etching and then determining the resulting etch pit density (EPD). The etching technique involves potassium hydroxide and has been qualified through correlation with x-ray topography measurements of the dislocations. Measured EPD varied from 250 cm−2to 3×104cm−2. Other structural defects such as low angle grain boundaries, prismatic slip bands, inversion domains, have also been observed. The rare appearance of these defects will be discussed even though their role in the epitaxial growth of GaN and AlGaN is yet to be clarified.
Details of the improvement of crystalline quality of a-plane GaN using one-step lateral growth
Authors: Iida Daisuke , Nagai Tetsuya , Kawashima Takeshi , Miura Aya , Okadome Yoshizane , Tsuchiya Yosuke , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu 
Published: April 2011

ABSTRACTLow defect density a-plane GaN films were successfully grown by sidewall epitaxial lateral overgrowth (SELO) technique. Control of V/III ratio during the growth of GaN by metalorganic vapor phase epitaxy (MOVPE) was found to be very important to achieve a complete overgrowth on the SiO2 mask regions and atomically flat surface. The threading dislocation and stacking fault densities in the overgrown regions were lower than 106 cm−2 and 103 cm−1, respectively. The root mean square roughness was 0.09 nm. We also fabricated and characterized a-plane-GaN-based-light-emitting diodes (LEDs) using SELO technique. The light output power of the blue-green LED steeply increased with the decrease of threading dislocation density from 1010 cm−2 to 108 cm−2 and tended to saturate at lower dislocation densities.
Comparison of the Incorporation of Various Transition Metals into GaN by MOCVD
Authors: Kane Matthew H , Fenwick William , Li Nola , Gupta Shalini , Park Eun Hyun , Ferguson Ian T 
Published: April 2011

ABSTRACTThe incorporation of transition metals in GaN has long been of interest in spintronics due to theoretical predictions of room temperature ferromagnetism in these materials. However, the mechanism of the observed ferromagnetism of the nitride-based DMS is still controversial, and may originate from a carrier-mediated, defect-related or nanoscale clustering mechanism. In this work, we present a comparative study of the incorporation of various transition metals and their effect on the optical, structural, and magnetic properties of GaN. Metal-organic chemical vapor deposition (MOCVD) has been employed to produce epitaxial films of varying thickness and manganese and iron doping using bis-cyclopentyldienyl(magnanese,iron) as the transition metal sources. High-resolution X-ray diffraction reveals no secondary phases under optimized growth conditions. Magnetic hysteresis is observed at room temperature in both GaMnN and GaFeN, though the strength of the magnetic ordering is roughly an order of magnitude weaker in the Fe-alloyed samples. Increasing Mn concentrations significantly affect long-range lattice ordering, and the observation of local vibrational modes (LVMs) supports the formation of nitrogen vacancies, even under optimized MOCVD growth conditions. Such vacancies form shallow donor complexes and thus contribute to self-compensation. A disorder-induced mode at 300 cm−1 and a LVM due to vacancies at 669 cm-1 were revealed by Raman spectroscopy.