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Mobility bands

Yo-Han Kim, Eun Yeol Lee, Hyun Ho Lee, Tae Seok Seo
Reduced graphene oxide quantum dot (rGOQD) devices in formats of capacitor and thin film transistor (TFT) were demonstrated and examined as the first trial to achieve non-ambipolar channel property. In addition, through gold nanoparticles (Au NPs) layer embedded between the rGOQD active channel and dielectric layer, memory capacitor and TFT performances were realized by capacitance-voltage (C-V) hysteresis and gate program, erase, and reprogram biases. First, capacitor structure of the rGOQD memory device was constructed to examine memory charging effect featured in hysteretic C-V behavior with a 30 nm dielectric layer of crosslinked polyvinyl alcohol (PVA)...
April 26, 2017: ACS Applied Materials & Interfaces
Daniel Ouedraogo, Michael Souffrant, Sheena Vasquez, Donald Hamelberg, Giovanni Gadda
Mobile loops located at the active site entrance in enzymes often participate in conformational changes required to shield the reaction from bulk solvent, to control substrate access to the active site, and to position residues for substrate binding and catalysis. In D-arginine dehydrogenase from Pseudomonas aeruginosa (PaDADH) previous crystallographic data suggested that residues 45-47 in the FAD-binding domain and 50-56 in the substrate-binding domain in loop L1 could adopt two distinct conformations. In this study, we have used molecular dynamics, kinetics, and fluorescence spectroscopy on the S45A and A46G enzyme variants of PaDADH to investigate the impact of mutations of loop L1 on the catalytic function of the enzyme...
April 26, 2017: Biochemistry
Qian Cheng, Manpuneet Kaur Benipal, Qianlang Liu, Xingye Wang, Peter A A Crozier, Candace K Chan, Robert J Nemanich
Strategies for protecting unstable semiconductors include the utilization of surface layers comprised of thin films deposited using atomic layer deposition (ALD). The protective layer is expected to: (1) be stable against reaction with photogenerated holes, (2) prevent direct contact of the unstable semiconductor with the electrolyte, and (3) prevent the migration of ions through the semiconductor/electrolyte interface, while still allowing photogenerated carriers to transport to the interface and participate in the desired redox reactions...
April 25, 2017: ACS Applied Materials & Interfaces
Minkyu Sung, Seung-Hyun Cho, Hwan Seok Chung, Sun Me Kim, Jong Hyun Lee
We demonstrate the improvement of the transmission performance based on intermixing noise mitigation techniques in a multiple intermediate-frequency-over-fiber (IFoF) based mobile fronthaul. The interaction between fiber chromatic dispersion and frequency chirp of the directly modulated laser generates the second-order distortion that degrades the performance of multi-IFoF transmission system. To avoid second-order distortion, we use intermediate frequency (IF) spacing optimization and octave-confined frequency plan schemes in which intermixing noise would be generated in the out of signal band and would not affect the quality of transmitted signal...
April 17, 2017: Optics Express
Hendrik Faber, Satyajit Das, Yen-Hung Lin, Nikos Pliatsikas, Kui Zhao, Thomas Kehagias, George Dimitrakopulos, Aram Amassian, Panos A Patsalas, Thomas D Anthopoulos
Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100...
March 2017: Science Advances
Yanhui Wang, Susan V Olesik
An ion-exchange method to separate charged biomolecules on ultrathin layer chromatographic (UTLC) plates using electrospun Nafion-Polyacrylonitrile (PAN) nanofibers as the stationary phase is described. Sulfonate groups on Nafion provide the ion-exchange sites. The addition of PAN (a higher molecular weight polymer than Nafion) was used to facilitate the nanofiber formation process using electrospinning. Electrospinning parameters and separation conditions were optimized using fractional factorial design and response surface methodology...
June 1, 2017: Analytica Chimica Acta
Haidong Zhang, Hanyu Liu, Kaya Wei, Oleksandr O Kurakevych, Yann Le Godec, Zhenxian Liu, Joshua Martin, Michael Guerrette, George S Nolas, Timothy A Strobel
Large-volume, phase-pure synthesis of BC8 silicon (Ia3[over ¯], cI16) has enabled bulk measurements of optical, electronic, and thermal properties. Unlike previous reports that conclude BC8-Si is semimetallic, we demonstrate that this phase is a direct band gap semiconductor with a very small energy gap and moderate carrier concentration and mobility at room temperature, based on far- and midinfrared optical spectroscopy, temperature-dependent electrical conductivity, Seebeck and heat capacity measurements...
April 7, 2017: Physical Review Letters
Chun-Sheng Liu, Hao-Hao Zhu, Xiao-Juan Ye, Xiao-Hong Yan
Recently, there has been a growing interest in exploring planar hypercoordinate carbons in two-dimensional nanostructures. However, atomic monolayers with ideal planar hypercoordinate carbon are quite rare due to the challenge in stabilizing the exotic motifs. We predicted a global minimum two-dimensional BeC monolayer using the global particle-swarm optimization method. Each carbon binds peripheral four atoms in the same plane, forming a perfectly planar tetracoordinate carbon moiety. The cohesive energy, phonon-spectrum and mechanical stability criteria confirm the stability of monolayer BeC...
April 21, 2017: Nanoscale
B Dong, A Oyelade, J A Kelber
Semiconducting boron carbides based on cross-linked carborane (B10C2H12) icosahedra, developed several decades ago, are of significant interest in a variety of emerging areas, including photocatalysis, spintronics, and especially neutron detection. These materials, however, display generally poor charge carrier mobility, high defect levels and other properties that pose significant drawbacks. A class of nanocomposite carborane-based materials has recently been developed, that addresses many of these issues...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
K Takase, Y Ashikawa, G Zhang, K Tateno, S Sasaki
III-V semiconductors have been intensively studied with the goal of realizing metal-oxide-semiconductor field-effect transistors (MOSFETs) with high mobility, a high on-off ratio, and low power consumption as next-generation transistors designed to replace current Si technology. Of these semiconductors, a narrow band-gap semiconductor InAs has strong Rashba spin-orbit interaction, thus making it advantageous in terms of both high field-effect transistor (FET) performance and efficient spin control. Here we report a high-performance InAs nanowire MOSFET with a gate-all-around (GAA) structure, where we simultaneously control the spin precession using the Rashba interaction...
April 19, 2017: Scientific Reports
Murat Kaya Yapici, Tamador Elboshra Alkhidir
Biopotential signals are recorded mostly by using sticky, pre-gelled electrodes, which are not ideal for wearable, point-of-care monitoring where the usability of the personalized medical device depends critically on the level of comfort and wearability of the electrodes. We report a fully-wearable medical garment for mobile monitoring of cardiac biopotentials from the wrists or the neck with minimum restriction to regular clothing habits. The wearable prototype is based on elastic bands with graphene functionalized, textile electrodes and battery-powered, low-cost electronics for signal acquisition and wireless transmission...
April 16, 2017: Sensors
Luca Sementa, Luca Larcher, Giovanni Barcaro, Monia Montorsi
We report ab initio results for sub-stoichiometric HfOx with different oxygen vacancy densities, useful in exploring microscopic mechanisms that govern the operation of RRAM devices. We demonstrate that oxygen vacancy filaments are energetically more stable than randomly distributed defects. Furthermore, the stability of the filaments increases with the number of confined oxygen vacancies. Energetic and structural analyses show that bonds between neighboring coordinative unsaturated Hf atoms promote filament stability, and electron trapping, due to electron injection, increases the cohesive energy until the injection is moderate...
April 18, 2017: Physical Chemistry Chemical Physics: PCCP
Chika Ohashi, Seiichiro Izawa, Yusuke Shinmura, Mitsuru Kikuchi, Seiji Watase, Masanobu Izaki, Hiroyoshi Naito, Masahiro Hiramoto
The standard technique to separately and simultaneously determine the carrier concentration per unit volume (N, cm(-3) ) and the mobility (μ) of doped inorganic single crystals is to measure the Hall effect. However, this technique has not been reported for bulk-doped organic single crystals. Here, the Hall effect in bulk-doped single-crystal organic semiconductors is measured. A key feature of this work is the ultraslow co-deposition technique, which reaches as low as 10(-9) nm s(-1) and enables us to dope homoepitaxial organic single crystals with acceptors at extremely low concentrations of 1 ppm...
April 18, 2017: Advanced Materials
Hayden J Danyluk, Leona K Shum, Wesley F Zandberg
Purified glycan standards are required for glycan arrays, characterizing substrate specificities of glycan-active enzymes, and to serve as retention-time or mobility standards for various separation techniques. This chapter describes a method for the rapid separation, and subsequent desalting, of glycans labeled with the highly fluorescent fluorophore 8-aminopyrene 1,3,6-trisulfonate (APTS). By using fluorophore-assisted carbohydrate electrophoresis (FACE) on polyacrylamide gels, which utilizes equipment readily available in most molecular biology laboratories, many APTS-labeled glycans can be simultaneously resolved...
2017: Methods in Molecular Biology
Luiz Antonio Ribeiro, Wiliam Ferreira da Cunha, Antonio Luciano de Almeida Fonseca, Geraldo Magela E Silva
The transport of polarons above the mobility threshold in organic and inorganic polymers is theoretically investigated in the framework of a one-dimensional tight-binding model that includes lattice relaxation. The computational approach is based on parameters for which the model Hamiltonian suitably describes different polymer lattices in the presence of external electric fields. Our findings show that, above critical field strengths, a dissociated polaron moves through the polymer lattice as a free electron performing Bloch oscillations...
April 14, 2017: Journal of Chemical Physics
Andrew J S Valentine, Dmitri V Talapin, David A Mazziotti
Recent work found that soldering CdTe quantum dots together with a molecular CdTe polymer yielded field-effect transistors with much greater electron mobility than quantum dots alone. We present a computational study of the CdTe polymer using the active-space variational two-electron reduced density matrix (2-RDM) method. While analogous complete active-space self-consistent field (CASSCF) methods scale exponentially with the number of active orbitals, the active-space variational 2-RDM method exhibits polynomial scaling...
April 13, 2017: Journal of Physical Chemistry. A
Jinxiong Wu, Congwei Tan, Zhenjun Tan, Yujing Liu, Jianbo Yin, Wenhui Dang, Mingzhan Wang, Hailin Peng
Non-neutral layered crystals, another group of two-dimensional (2D) materials that lack a well-defined van der Waals (vdWs) gap, are those that form strong chemical bonds in-plane but display weak out-of-plane electrostatic interactions, exhibiting intriguing properties for the bulk counterpart. However, investigation of the properties of their atomically thin counterpart are very rare presumably due to the absence of efficient ways to achieve large-area high-quality 2D crystals. Here, high-mobility atomically thin Bi2O2Se, a typical non-neutral layered crystal without a standard vdWs gap, was synthesized via a facial chemical vapor deposition (CVD) method, showing excellent controllability for thickness, domain size, nucleation site, and crystal-phase evolution...
April 11, 2017: Nano Letters
Wenzhi Yu, Shaojuan Li, Yupeng Zhang, Weiliang Ma, Tian Sun, Jian Yuan, Kai Fu, Qiaoliang Bao
2D transition metal dichalcogenides (TMDCs) have attracted considerable attention due to their impressively high performance in optoelectronic devices. However, efficient infrared (IR) photodetection has been significantly hampered because the absorption wavelength range of most TMDCs lies in the visible spectrum. In this regard, semiconducting 2D MoTe2 can be an alternative choice owing to its smaller band gap ≈1 eV from bulk to monolayer and high carrier mobility. Here, a MoTe2 /graphene heterostructure photodetector is demonstrated for efficient near-infrared (NIR) light detection...
April 11, 2017: Small
Gordon Hithell, Mario González-Jiménez, Gregory M Greetham, Paul M Donaldson, Michael Towrie, Anthony W Parker, Glenn A Burley, Klaas Wynne, Neil T Hunt
Changes in the structural and solvation dynamics of a 15mer AT DNA duplex upon melting of the double-helix are observed by a combination of ultrafast two-dimensional infrared (2D-IR) and optical Kerr-effect (OKE) spectroscopies. 2D-IR spectroscopy of the vibrational modes of the DNA bases reveal signature off-diagonal peaks arising from coupling and energy transfer across Watson-Crick paired bases that are unique to double-stranded DNA (ds-DNA). Spectral diffusion of specific base vibrational modes report on the structural dynamics of the duplex and the minor groove, which is predicted to contain a spine of hydration...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
Huabing Shu, Yilong Tong, Jiyuan Guo
In zero-gap semimetallic silicene, introducing a sizable band gap without degrading its high carrier mobility is vital to its application in optoelectronic devices. Herein, we design a novel atomically thin system based on silicene and arsenene nanocomposites (Si/As heterostructure), which could open a direct band gap of about 125 meV at the K point in silicene. Moreover, its band gap is linearly controllable over a wide range even with a semiconductor-metal transition by the external electric field (E⊥), with an impressive band gap of up to 328 meV at E⊥ = -0...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
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