bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Gd substitution on the structural, magnetic, and magnetocaloric properties of HoCrO3
Authors: Yin Shiqi , Zhong Wei , Guild Curtis J. , Shi Jianhang , Suib Steven L. , Cótica Luiz Fernando , Jain Menka
Published: February 2018

Rare-earth chromites are a new type of magnetoelectric multiferroics. In this work, a Ho0.33Gd0.67CrO3 powder sample was synthesized via a citrate route, and the structural properties were characterized by X-ray diffraction, scanning electron microscopy, and the Raman technique. The UV-Visible optical absorbance spectra were also measured in the wavelength range of 200–800 nm. The valence state of Cr was found to be purely 3+ according to the X-ray photoelectron spectroscopy. The temperature-dependent dielectric constant and loss tangent data measured between the frequencies of 1 kHz and 1 MHz show no anomalies around the magnetic transition temperature of the material. The dc magnetization measurements show that the ordering temperature of Cr3+ (TNCr) is 155 K for Ho0.33Gd0.67CrO3, which is larger than 140 K for HoCrO3. The positive slope of the Arrott plots from 0 T to 7 T reveals that the antiferromagnetic-paramagnetic phase transition is second-order in nature. At a field of 7 T, the Ho0.33Gd0.67CrO3 sample showed a giant magnetocaloric entropy change, −ΔS, of ∼23.3 J/kg K at 5 K, and a refrigeration capacity of ∼481.2 J/kg, which are much higher than those of pure bulk HoCrO3. This renders this material prospective for magnetic refrigeration in the low temperature (<30 K) range.
Kinetic analysis of single molecule FRET transitions without trajectories
Authors: Schrangl Lukas , Göhring Janett , Schütz Gerhard J.
Published: February 2018

Single molecule Förster resonance energy transfer (smFRET) is a popular tool to study biological systems that undergo topological transitions on the nanometer scale. smFRET experiments typically require recording of long smFRET trajectories and subsequent statistical analysis to extract parameters such as the states’ lifetimes. Alternatively, analysis of probability distributions exploits the shapes of smFRET distributions at well chosen exposure times and hence works without the acquisition of time traces. Here, we describe a variant that utilizes statistical tests to compare experimental datasets with Monte Carlo simulations. For a given model, parameters are varied to cover the full realistic parameter space. As output, the method yields p-values which quantify the likelihood for each parameter setting to be consistent with the experimental data. The method provides suitable results even if the actual lifetimes differ by an order of magnitude. We also demonstrated the robustness of the method to inaccurately determine input parameters. As proof of concept, the new method was applied to the determination of transition rate constants for Holliday junctions.
Dynamics of the OH stretching mode in crystalline Ba(ClO4)2·3H2O
Authors: Hutzler Daniel , Brunner Christian , Petkov Petko St. , Heine Thomas , Fischer Sighart F. , Riedle Eberhard , Kienberger Reinhard , Iglev Hristo
Published: February 2018

The vibrational dynamics of the OH stretching mode in Ba(ClO4)2 trihydrate are investigated by means of femtosecond infrared spectroscopy. The sample offers plane cyclic water trimers in the solid phase that feature virtually no hydrogen bond interaction between the water molecules. Selective excitation of the symmetric and asymmetric stretching leads to fast population redistribution, while simultaneous excitation yields quantum beats, which are monitored via a combination tone that dominates the overtone spectrum. The combination of steady-state and time-resolved spectroscopy with quantum chemical simulations and general theoretical considerations gives indication of various aspects of symmetry breakage. The system shows a joint population lifetime of 8 ps and a long-lived coherence between symmetric and asymmetric stretching, which decays with a time constant of 0.6 ps.
Insight into ethylene interactions with molybdenum suboxide cluster anions from photoelectron spectra of chemifragments
Authors: Schaugaard Richard N. , Topolski Josey E. , Ray Manisha , Raghavachari Krishnan , Jarrold Caroline Chick
Published: February 2018

Recent studies on reactions between MoxOy− cluster anions and H2O/C2H4 mixtures revealed a complex web of addition, hydrogen evolution, and chemifragmentation reactions, with chemifragments unambiguously connected to cluster reactions with C2H4. To gain insight into the molecular-scale interactions along the chemifragmentation pathways, the anion photoelectron (PE) spectra of MoC2H2−, MoC4H4−, MoOC2H2−, and MoO2C2H2− formed directly in MoxOy− + C2H4 (x > 1; y ≥ x) reactions, along with supporting CCSD(T) and density functional theory calculations, are presented and analyzed. The complexes have spectra that are all consistent with η2-acetylene complexes, though for all but MoC4H4−, the possibility that vinylidene complexes are also present cannot be definitively ruled out. Structures that are consistent with the PE spectrum of MoC2H2− differ from the lowest energy structure, suggesting that the fragment formation is under kinetic control. The PE spectrum of MoO2C2H2− additionally exhibits evidence that photodissociation to MoO2− + C2H2 may be occurring. The results suggest that oxidative dehydrogenation of ethylene is initiated by Lewis acid/base interactions between the Mo centers in larger clusters and the π orbitals in ethylene.
Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector
Authors: Seimetz M. , Bellido P. , García P. , Mur P. , Iborra A. , Soriano A. , Hülber T. , García López J. , Jiménez-Ramos M. C. , Lera R. , Ruiz-de la Cruz A. , Sánchez I. , Zaffino R. , Roso L. , Benlloch J. M.
Published: February 2018

CR-39 nuclear track material is frequently used for the detection of protons accelerated in laser-plasma interactions. The measurement of track densities allows for determination of particle angular distributions, and information on the kinetic energy can be obtained by the use of passive absorbers. We present a precise method of measuring spectral distributions of laser-accelerated protons in a single etching and analysis process. We make use of a one-to-one relation between proton energy and track size and present a precise calibration based on monoenergetic particle beams. While this relation is limited to proton energies below 1 MeV, we show that the range of spectral measurements can be significantly extended by simultaneous use of absorbers of suitable thicknesses. Examples from laser-plasma interactions are presented, and quantitative results on proton energies and particle numbers are compared to those obtained from a time-of-flight detector. The spectrum end points of continuous energy distributions have been determined with both detector types and coincide within 50-100 keV.
A shell-resolved analysis of preferential solvation of coffee ingredients in aqueous mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate
Authors: Zeindlhofer Veronika , Berger Magdalena , Steinhauser Othmar , Schröder Christian
Published: February 2018

Ionic liquids increase the solubility of various coffee ingredients in aqueous solution but little is known about the underlying mechanism. Kirkwood-Buff integrals as well as the potential of mean force indicate that the imidazolium cations are accumulated at the surface of the solutes, removing water molecules from the solute surface. Although hydrogen bonding of the anions to hydroxy groups of the solutes can be detected, their concentration at the surface is less enhanced compared to the cations. The decomposition into solvation shells by Voronoi tessellation reveals that structural features are only observed in the first solvation shell. Nevertheless, the depletion of water and the excess concentration of the ions and, in particular, of the cations are visible in the next solvation shells as well. Therefore, classical arguments of hydrotropic theory fail to explain this behavior.
Focus Article: Oscillatory and long-range monotonic exponential decays of electrostatic interactions in ionic liquids and other electrolytes: The significance of dielectric permittivity and renormalized charges
Authors: Kjellander Roland
Published: February 2018

A unified treatment of oscillatory and monotonic exponential decays of interactions in electrolytes is displayed, which highlights the role of dielectric response of the fluid in terms of renormalized (effective) dielectric permittivity and charges. An exact, but physically transparent statistical mechanical formalism is thereby used, which is presented in a systematic, pedagogical manner. Both the oscillatory and monotonic behaviors are given by an equation for the decay length of screened electrostatic interactions that is very similar to the classical expression for the Debye length. The renormalized dielectric permittivities, which have similar roles for electrolytes as the dielectric constant has for pure polar fluids, consist in general of several entities with different physical meanings. They are connected to dielectric response of the fluid on the same length scale as the decay length of the screened interactions. Only in cases where the decay length is very long, these permittivities correspond approximately to a dielectric response in the long-wavelength limit, like the dielectric constant for polar fluids. Experimentally observed long-range exponentially decaying surface forces are analyzed as well as the oscillatory forces observed for short to intermediate surface separations. Both occur in some ionic liquids and in concentrated as well as very dilute electrolyte solutions. The coexisting modes of decay are in general determined by the bulk properties of the fluid and not by the solvation of the surfaces; in the present cases, they are given by the behavior of the screened Coulomb interaction of the bulk fluid. The surface-fluid interactions influence the amplitudes and signs or phases of the different modes of the decay, but not their decay lengths and wavelengths. The similarities between some ionic liquids and very dilute electrolyte solutions as regards both the long-range monotonic and the oscillatory decays are analyzed.
Design of a multiband near-infrared sky brightness monitor using an InSb detector
Authors: Dong Shu-cheng , Wang Jian , Tang Qi-jie , Jiang Feng-xin , Chen Jin-ting , Zhang Yi-hao , Wang Zhi-yue , Chen Jie , Zhang Hong-fei , Jiang Hai-jiao , Zhu Qing-feng , Jiang Peng , Ji Tuo
Published: February 2018

Infrared sky background level is an important parameter of infrared astronomy observations from the ground, particularly for a candidate site of an infrared capable observatory since low background level is required for such a site. The Chinese astronomical community is looking for a suitable site for a future 12 m telescope, which is designed for working in both optical and infrared wavelengths. However, none of the proposed sites has been tested for infrared observations. Nevertheless, infrared sky background measurements are also important during the design of infrared observing instruments. Based on the requirement, in order to supplement the current site survey data and guide the design of future infrared instruments, a multiband near-infrared sky brightness monitor (MNISBM) based on an InSb sensor is designed in this paper. The MNISBM consists of an optical system, mechanical structure and control system, detector and cooler, high gain readout electronics, and operational software. It is completed and tested in the laboratory. The results show that the sensitivity of the MNISBM meets the requirements of the measurement of near-infrared sky background level of several well-known astronomical infrared observing sites.
Coupled breathing modes in one-dimensional Skyrmion lattices
Authors: Kim Junhoe , Yang Jaehak , Cho Young-Jun , Kim Bosung , Kim Sang-Koog
Published: February 2018

We explored strong coupling of dynamic breathing modes in one-dimensional (1D) skyrmion lattices periodically arranged in thin-film nanostrips. The coupled breathing modes exhibit characteristic concave-down dispersions that represent the in-phase high-energy mode at zero wavenumber (k = 0) and the anti-phase low-energy mode at the Brillouin zone boundary (k = kBZ). The band width of the allowed modes increases with decreasing inter-distance between nearest-neighboring skyrmions. Furthermore, the collective breathing modes propagate very well through the thin-film nanostrips, as fast as 200–700 m/s, which propagation is controllable by the strength of magnetic fields applied perpendicularly to the film plane. The breathing modes in 1D skyrmion lattices potentially formed in such nanostrips possibly can be used as information carriers in information processing devices.
Enhancement of polar phase and conductivity relaxation in PIL-modified GO/PVDF composites
Authors: Xu Pei , Fu Weijia , Cui Zhaopei , Ding Yunsheng
Published: February 2018

To investigate the effect of graphene oxide (GO) modified by polymerized ionic liquid (PIL) on the crystallization and dielectric relaxation of poly(vinylidene fluoride) (PVDF), a series of PVDF composites have been prepared using the solution casting method. The ion-dipole interaction between PIL and >CF2 and the π-dipole interaction between GO and >CF2 can induce synergistically the polar phase, and the π-ion interaction between GO and PIL can strengthen the induction effect of the polar phase and decrease the degree of crystallization of PVDF. The electric modulus and conductivity relaxation are employed to analyze the experimental complex dielectric permittivity. In the frequency spectra of complex permittivity of PVDF composites, space charge polarization and conductivity lead to a large value of dielectric permittivity. The temperature dependence of relaxation time of conductivity relaxation accords with the Arrhenius equation. A low degree of crystallization, more ion concentration, and polar phase in PVDF/PIL/GO enhance the movement of the polymer chain segment and charge carriers.
Formation of the nitrogen aggregates in annealed diamond by neutron irradiation
Authors: Mita Y. , Nisida Y. , Okada M.
Published: February 2018

Neutron heavy irradiation was performed on synthetic diamonds contain nitrogen atoms in isolated substitutional form (called “type Ib diamond”) and they were annealed under a pressure of 6 GPa. A large number of nitrogen B-aggregate which consists of four substitutional nitrogen atoms symmetrically surrounding a vacancy was formed within 30 m from single nitrogen atoms. Furthermore it is observed that, in these diamonds, single nitrogen atoms coexist with the B-aggregates, which is unexplainable by the simple nitrogen aggregation model.
Misfit dislocation–related deep levels in InGaAs/GaAs and GaAsSb/GaAs p–i–n heterostructures and the effect of these on the relaxation time of nonequilibrium carriers
Authors: Sobolev M. M. , Soldatenkov F. Yu. , Shul'pina I. L.
Published: February 2018

A study of deep levels in InGaAs/GaAs and GaAsSb/GaAs p0–i–n0 heterostructures with misfit dislocations and identification of the effective defects responsible for the significant (by up to a factor of 100) decrease in the relaxation time of nonequilibrium carriers in the base layers (and in the related reverse recovery time) of InGaAs/GaAs and GaAsSb/GaAs high-voltage power p-i-n diodes is reported. Experimental capacitance–voltage characteristics and deep-level transient spectroscopy spectra of p+–p0–i–n0–n+ homostructures based on undoped GaAs layers without misfit dislocations and InGaAs/GaAs and GaAsSb/GaAs heterostructures with a homogeneous network of misfit dislocations, all grown by liquid-phase epitaxy, are analyzed. Acceptor defects with deep levels HL2 and HL5 are identified in GaAs epitaxial p0 and n0 layers. Dislocation-related electron and hole deep traps designated as ED1 and HD3 are detected in InGaAs/GaAs and GaAsSb/GaAs heterostructures. The effective recombination centers in the heterostructure layers, to which we attribute the substantial decrease in the relaxation time of nonequilibrium carriers in the base layers of p-i-n diodes, are dislocation-related hole traps that are similar to HD3 and have the following parameters: thermal activation energy Et = 845 meV, carrier capture cross-section σp = 1.33 × 10−12 cm2, concentration Nt = 3.80 × 1014 cm−3 for InGaAs/GaAs and Et = 848 meV, σp = 2.73 × 10−12 cm2, and Nt = 2.40 × 1014 cm−3 for the GaAsSb/GaAs heterostructure. The relaxation time of the concentration of nonequilibrium carriers in the presence of dislocation-related deep acceptor traps similar to HD3 was estimated to be 1.1 × 10−10 and 8.5 × 10−11 s for, respectively, the InGaAs/GaAs and GaAsSb/GaAs heterostructures and 8.9 × 10−7 s for the GaAs homostructure. These data correspond to the relaxation times of nonequilibrium carriers in the base layers of GaAs, InGaAs/GaAs, and GaAsSb/GaAs high-voltage power p-i-n diodes.
Two-electrons quantum dot in plasmas under the external fields
Authors: Bahar M. K. , Soylu A.
Published: February 2018

In this study, for the first time, the combined effects of the external electric field, magnetic field, and confinement frequency on energies of two-electron parabolic quantum dots in Debye and quantum plasmas modeled by more general exponential cosine screened Coulomb (MGECSC) potential are investigated by numerically solving the Schrödinger equation using the asymptotic iteration method. The MGECSC potential includes four different potential forms when considering different sets of the parameters in potential. Since the plasma is an important experimental argument for quantum dots, the influence of plasmas modeled by the MGECSC potential on quantum dots is probed. The confinement frequency of quantum dots and the external fields created significant quantum restrictions on quantum dot. In this study, as well as discussion of the functionalities of the quantum restrictions for experimental applications, the parameters are also compared with each other in terms of influence and behaviour. In this manner, the motivation points of this study are summarized as follows: Which parameter can be alternative to which parameter, in terms of experimental applications? Which parameters exhibit similar behaviour? What is the role of plasmas on the corresponding behaviours? In the light of these research studies, it can be said that obtained results and performed discussions would be important in experimental and theoretical research related to plasma physics and/or quantum dots.
Modeling study on the effects of pulse rise rate in atmospheric pulsed discharges
Authors: Zhang Yuan-Tao , Wang Yan-Hui
Published: February 2018

In this paper, we present a modeling study on the discharge characteristics driven by short pulsed voltages, focusing on the effects of pulse rise rate based on the fluid description of atmospheric plasmas. The numerical results show that the breakdown voltage of short pulsed discharge is almost linearly dependent on the pulse rise rate, which is also confirmed by the derived equations from the fluid model. In other words, if the pulse rise rate is fixed as a constant, the simulation results clearly suggest that the breakdown voltage is almost unchanged, although the amplitude of pulsed voltage increases significantly. The spatial distribution of the electric field and electron density are given to reveal the underpinning physics. Additionally, the computational data and the analytical expression also indicate that an increased repetition frequency can effectively decrease the breakdown voltage and current density, which is consistent with the experimental observation.
Electron acoustic waves in a plasma with a q-nonextensive distribution of electrons
Authors: Aman-ur-Rehman  , Lee J. K.
Published: February 2018

Using a kinetic theoretical approach, the characteristics of electron acoustic waves (EAWs) have been studied in a plasma whose electron velocity distributions are modeled by a q-nonextensive distribution function. Analytical expressions have been derived to show the dependence of the phase velocity of EAWs on nonextensive parameter q for different ranges of wavelengths of EAWs. These expressions show that in all three regions (i.e., long wavelength, intermediate wavelength, and short wavelength regions), the dispersion of EAWs depends on the nonextensive parameter q. The numerical solution of the dispersion relation has been obtained to identify strongly and weakly damped regions of the EAWs. The results show that the range of wavenumbers for which EAWs are weakly damped depends strongly on the nonextensive parameter q. The smaller values of nonextensive parameter q mean more nonthermal electrons and hence the narrow range of the weakly damped region of EAWs. In the limit q→1, the results of the Maxwellian distribution function can be obtained from the results of the q nonextensive distribution function.
A real-time extension of density matrix embedding theory for non-equilibrium electron dynamics
Authors: Kretchmer Joshua S. , Chan Garnet Kin-Lic
Published: February 2018

We introduce real-time density matrix embedding theory (DMET), a dynamical quantum embedding theory for computing non-equilibrium electron dynamics in strongly correlated systems. As in the previously developed static DMET, real-time DMET partitions the system into an impurity corresponding to the region of interest coupled to the surrounding environment, which is efficiently represented by a quantum bath of the same size as the impurity. In this work, we focus on a simplified single-impurity time-dependent formulation as a first step toward a multi-impurity theory. The equations of motion of the coupled impurity and bath embedding problem are derived using the time-dependent variational principle. The accuracy of real-time DMET is compared to that of time-dependent complete active space self-consistent field (TD-CASSCF) theory and time-dependent Hartree-Fock (TDHF) theory for a variety of quantum quenches in the single impurity Anderson model (SIAM), in which the Hamiltonian is suddenly changed (quenched) to induce a non-equilibrium state. Real-time DMET shows a marked improvement over the mean-field TDHF, converging to the exact answer even in the non-trivial Kondo regime of the SIAM. However, as expected from analogous behavior in static DMET, the constrained structure of the real-time DMET wavefunction leads to a slower convergence with respect to active space size, in the single-impurity formulation, relative to TD-CASSCF. Our initial results suggest that real-time DMET provides a promising framework to simulate non-equilibrium electron dynamics in which strong electron correlation plays an important role, and lays the groundwork for future multi-impurity formulations.
Water adsorbate phases on ZnO and impact of vapor pressure on the equilibrium shape of nanoparticles
Authors: Kenmoe Stephane , Biedermann P. Ulrich
Published: February 2018

ZnO nanoparticles are used as catalysts and have potential applications in gas-sensing and solar energy conversion. A fundamental understanding of the exposed crystal facets, their surface chemistry, and stability as a function of environmental conditions is essential for rational design and improvement of synthesis and properties. We study the stability of water adsorbate phases on the non-polar low-index (101¯0) and (112¯0) surfaces from low coverage to multilayers using ab initio thermodynamics. We show that phonon contributions and the entropies due to a 2D lattice gas at low coverage and multiple adsorbate configurations at higher coverage have an important impact on the stability range of water adsorbate phases in the (T,p) phase diagram. Based on this insight, we compute and analyze the possible growth mode of water films for pressures ranging from UHV via ambient conditions to high pressures and the impact of water adsorption on the equilibrium shape of nanoparticles in a humid environment. A 2D variant of the Wulff construction shows that the (101¯0) and (112¯0) surfaces coexist on 12-faceted prismatic ZnO nanoparticles in dry conditions, while in humid environment, the (101¯0) surface is selectively stabilized by water adsorption resulting in hexagonal prisms.
Nanoscale organization in the fluorinated room temperature ionic liquid: Tetraethyl ammonium (trifluoromethanesulfonyl)(nonafluorobutylsulfonyl)imide
Authors: Lo Celso F. , Appetecchi G. B. , Jafta C. J. , Gontrani L. , Canongia Lopes J. N. , Triolo A. , Russina O.
Published: February 2018

Fluorinated Room Temperature Ionic Liquids (FRTILs) are a branch of ionic liquids that is the object of growing interest for a wide range of potential applications, due to the synergic combination of specifically ionic features and those properties that stem from fluorous tails. So far limited experimental work exists on the micro- and mesoscopic structural organization in this class of compounds. Such a work is however necessary to fully understand morphological details at atomistic level that would have strong implications in terms of bulk properties. Here we use the synergy between X-ray and neutron scattering together with molecular dynamics simulations to access structural details of a technologically relevant FRTIL that is characterised by an anion bearing a long enough fluorinated tail to develop specific morphological features. In particular, we find the first experimental evidence that in FRTILs bearing an asymmetric bis(perfluoroalkyl)sulfonyl-imide anion, fluorous side chains tend to be spatially segregated into nm-scale spatial heterogeneities. This feature together with the well-established micro-segregation of side alkyl chains in conventional RTILs leads to the concept of triphilic ILs, whose technological applications are yet to be fully developed.
Monoclinic to cubic phase transformation and photoluminescence properties in Hf1−xSmxO2 (x = 0–0.12) nanoparticles
Authors: Kumar Sandeep , Rai S. B. , Rath Chandana
Published: February 2018

Bulk hafnium oxide (HfO2) exhibits the monoclinic phase at room temperature which transforms to tetragonal and cubic phases at 1700 and 2600 °C, respectively, under ambient conditions. For the first time, we observe a monoclinic to stable cubic phase transformation at room temperature in nanoparticles of HfO2 by incorporating Sm3+ ions up to 12 at. %. Although the monoclinic structure is retained at 1 at. % of Sm, a mixed phase of monoclinic and cubic is observed at intermediate Sm concentration (5–11 at. %). Le-Bail profile refinement of X-ray diffraction patterns confirms the monoclinic to cubic phase transformation with increasing Sm3+ ion concentration. While the significant difference in ionic radii of Sm3+ and Hf4+ ion induces strain in the lattice above 9 at. %, a lower valency of Sm produces oxygen vacancy leading to 8-fold coordination with Sm3+ ion and stabilizes the cubic phase at room temperature. Not only the particle size obtained from transmission electron micrograph (TEM) matches well with the size calculated from the Williamson-Hall plot, the lattice spacing estimated from high resolution TEM also confirms the monoclinic and cubic phases in HfO2 and Hf0.88Sm0.12O2, respectively. Apart from phase transformation induced by Sm3+ ions, photoluminescence studies demonstrate an excellent emission in near green and red regions in Hf1−xSmxO2 nanoparticles. A schematic energy band diagram has been proposed based on the excitation and emission processes involved in HfO2 and Hf0.99Sm0.01O2 nanoparticles.
Optical properties of Cr-doped Zn1−xMnxTe semimagnetic nanocrystals
Authors: Silva Alessandra S. , Lourenço Sidney A. , da Silva Marco Aurélio T. , Dantas Noelio O.
Published: February 2018

The effect of Cr co-doping on the optical properties of Mn-doped ZnTe nanocrystals (NCs) embedded in a glass matrix is studied in this paper. The substitutional incorporation of Cr2+ ions into these semiconducting NCs was strongly evidenced by optical absorption and crystal field theory analyses, which showed the characteristic transitions of Cr2+ and Cr3+ ions. Transmission electron microscopy images revealed the NC size and invariance lattice parameter, with the incorporation of Mn2+ and Cr2+ ions. PL spectra showed that co-doping with Cr favors a competition between Mn2+ and Cr2+ ions, resulting in a decrease in the rate of Mn2+ substitution, zinc vacancy filling (VZn) in Zn1−x−yMnxCryTe NCs, and the formation of interstitial Cr3+ ions in the host glass system.
Tuning the optical bandgap in multi-cation compound transparent conducting-oxides: The examples of In2ZnO4 and In4Sn3O12
Authors: Sabino Fernando P. , Oliveira Luiz N. , Wei Su-Huai , Da Silva Juarez L. F.
Published: February 2018

Transparent conducting oxides such as the bixbyite In2O3 and rutile SnO2 systems have large disparities between the optical and fundamental bandgaps, ΔEgOF, because selection rules forbid dipolar transitions from the top of the valence band to the conduction-band minimum; however, the optical gaps of multi-cation compounds with the same chemical species often coincide with their fundamental gaps. To explain this conundrum, we have employed density-functional theory to compute the optical properties of multi-cation compounds, In2ZnO4 and In4Sn3O12, in several crystal structures. We show that a recently proposed mechanism to explain the disparity between the optical and fundamental gaps of M2O3 (M = Al, Ga, and In) applies also to other binary systems and to multi-compounds. Namely, a gap disparity will arise if the following three conditions are satisfied: (i) the crystal structure has inversion symmetry; (ii) the conduction-band minimum is formed by the cation and O s-orbitals; and (iii) there is strong p-d coupling and weak p-p in the vicinity of the valence-band maximum. The third property depends critically on the cationic chemical species. In the structures with inversion symmetry, Zn (Sn) strengthens (weakens) the p-d coupling in In2ZnO4 (In4Sn3O12), enhancing (reducing) the gap disparity. Furthermore, we have also identified a In4Sn3O12 structure that is 31.80 meV per formula unit more stable than a recently proposed alternative model.
Light-controlled stateful logic operations using optoelectronic switches based on p-Si/HfO2 heterostructures
Authors: Chen Yan , Zhu Shengju , Wei Qi , Xia Yidong , Li Aidong , Yin Jiang , Liu Zhiguo
Published: February 2018

In this work, we present light-controlled resistive switches with p-Si/HfO2/Pt structures, in which the resistance can be controlled by a combination of electrical pulses and light. The devices have a large switching ratio (over 104) and good uniformity. Connecting two devices with a conventional resistor enables one to implement light-controlled material implication (IMP). Based on the light-controlled IMP logic, light-controlled NAND and light-controlled OR logic operations were also executed in the same devices.
Polarization control of high transmission/reflection switching by all-dielectric metasurfaces
Authors: Shibanuma Toshihiko , Maier Stefan A. , Albella Pablo
Published: February 2018

Metasurfaces built of high refractive dielectric nanostructures could play a key role in controlling the electromagnetic wave propagation, due to their low energy losses and their ability to excite not only electric but also magnetic resonances. In this study, we theoretically and experimentally demonstrate that an array of high-index dielectric nanodimers can perform as tuneable metasurfaces that can be switched from a high transmitter to a high reflector, by just changing the linear polarization of excitation. The incident polarization alters the hybridization mode of the excited electric and magnetic dipoles in the dimer, and this leads to either spectral overlap or separation of the two dipoles. The hybridization of the electric and magnetic modes modifies the effective permittivity and permeability of the tuneable dielectric metasurface, exhibiting the high transmission and reflection that can be easily switched by simply changing the linear polarization.
Recombination activity of grain boundaries in high-performance multicrystalline Si during solar cell processing
Authors: Adamczyk Krzysztof , Søndenå Rune , Stokkan Gaute , Looney Erin , Jensen Mallory , Lai Barry , Rinio Markus , Di Sabatino Marisa
Published: February 2018

In this work, we applied internal quantum efficiency mapping to study the recombination activity of grain boundaries in High Performance Multicrystalline Silicon under different processing conditions. Wafers were divided into groups and underwent different thermal processing, consisting of phosphorus diffusion gettering and surface passivation with hydrogen rich layers. After these thermal treatments, wafers were processed into heterojunction with intrinsic thin layer solar cells. Light Beam Induced Current and Electron Backscatter Diffraction were applied to analyse the influence of thermal treatment during standard solar cell processing on different types of grain boundaries. The results show that after cell processing, most random-angle grain boundaries in the material are well passivated, but small-angle grain boundaries are not well passivated. Special cases of coincidence site lattice grain boundaries with high recombination activity are also found. Based on micro-X-ray fluorescence measurements, a change in the contamination level is suggested as the reason behind their increased activity.
Electric field measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond electric field induced second harmonic generation
Authors: Goldberg Benjamin M. , Chng Tat Loon , Dogariu Arthur , Miles Richard B.
Published: February 2018

We present an optical electric field measurement method for use in high pressure plasma discharges. The method is based upon the field induced second harmonic generation technique and can be used for localized electric field measurements with sub-nanosecond resolution in any gaseous species. When an external electric field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the electric field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the electric field is strong enough to exceed the breakdown threshold, the measured field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.
Local sensor based on nanowire field effect transistor from inhomogeneously doped silicon on insulator
Authors: Presnov Denis E. , Bozhev Ivan V. , Miakonkikh Andrew V. , Simakin Sergey G. , Trifonov Artem S. , Krupenin Vladimir A.
Published: February 2018

We present the original method for fabricating a sensitive field/charge sensor based on field effect transistor (FET) with a nanowire channel that uses CMOS-compatible processes only. A FET with a kink-like silicon nanowire channel was fabricated from the inhomogeneously doped silicon on insulator wafer very close (∼100 nm) to the extremely sharp corner of a silicon chip forming local probe. The single e-beam lithographic process with a shadow deposition technique, followed by separate two reactive ion etching processes, was used to define the narrow semiconductor nanowire channel. The sensors charge sensitivity was evaluated to be in the range of 0.1–0.2 e/Hz from the analysis of their transport and noise characteristics. The proposed method provides a good opportunity for the relatively simple manufacture of a local field sensor for measuring the electrical field distribution, potential profiles, and charge dynamics for a wide range of mesoscopic objects. Diagnostic systems and devices based on such sensors can be used in various fields of physics, chemistry, material science, biology, electronics, medicine, etc.
Photoinduced reversible lattice expansion in W-doped TiO2 through the change of its electronic structure
Authors: Feng Fan , Yang Weiyi , Gao Shuang , Zhu Linggang , Li Qi
Published: February 2018

External stimulations of applied force or voltage have been reported to induce crystal lattice dimension changes with the order of 0.1% or above by imposing external mechanical or electric forces on atoms forming the lattice for various types of materials, including oxides, metals, polymers, and carbon nanostructures. As far as we know, however, no report is available for similar level changes in oxides from their internal electronic structure changes induced by photoirradiation. We show that reversible lattice expansion comparable to those by applied force or voltage can be induced by UV-irradiation on an oxide of W-doped TiO2 nanotubes through the reversible changes of its internal electronic structure by the accumulation and release of photogenerated electrons in W-dopants when UV-illumination is on and off. This photoirradiation-induced reversible lattice expansion and subsequent optical, electric, and magnetic property changes may also be present in other material systems by proper material design if they possess one component that is able to produce electrons upon photoirradiation and the other component that is able to accumulate photogenerated electrons to induce lattice changes and release them after the photoirradiation is off.
Point spectrum of the Floquet Hamiltonian for Klein-Gordon equation under quasi-periodic perturbations
Authors: Fang Daoyuan , Han Zheng , Wang Weimin
Published: February 2018

In this paper, Anderson localization is proved for the Klein-Gordon operator under time quasi-periodic perturbations, by proving pure point spectrum of the associated Floquet Hamiltonian.
Reduction of lattice equations to the Painlevé equations: PIV and PV
Authors: Nakazono Nobutaka
Published: February 2018

In this paper, we construct a new relation between Adler-Bobenko-Suris equations and Painlevé equations. Moreover, using this connection we construct the difference-differential Lax representations of the fourth and fifth Painlevé equations.
Scanning microwave microscope algorithm offers robust calibration method for doped semiconductors
Authors: Liebendorfer Adam
Published: February 2018

One-port algorithm draws on classical vector network analyzer calibration to extract quantitative carrier densities from a semiconducting n-doped GaAs multilayer sample.
Septal cholinergic neurons gate hippocampal output to entorhinal cortex via oriens lacunosum moleculare interneurons
Authors: Haam Juhee , Zhou Jingheng , Cui Guohong , Yakel Jerrel L.
Published: February 2018

Significance

Memory formation is a complex process that involves information transfer to the hippocampus for temporary storage (i.e., encoding) and the reciprocal circuit that relays the temporary information back to the neocortex for long-term storage (i.e., consolidation). Acetylcholine has been shown to play a critical role in memory function by differentially modulating encoding and consolidation, but the underlying mechanism is yet unclear. We found that acetylcholine suppresses the hippocampus–entorhinal cortex pathway, which is the gateway to the consolidation pathway. We show that this inhibition is mediated by oriens lacunosum moleculare interneurons and that the ablation of these interneurons impairs proper memory encoding. We provide evidence that demonstrates how acetylcholine tones down the memory consolidation pathway for efficient memory encoding.
SLC39A14 deficiency alters manganese homeostasis and excretion resulting in brain manganese accumulation and motor deficits in mice
Authors: Jenkitkasemwong Supak , Akinyode Adenike , Paulus Elizabeth , Weiskirchen Ralf , Hojyo Shintaro , Fukada Toshiyuki , Giraldo Genesys , Schrier Jessica , Garcia Armin , Janus Christopher , Giasson Benoit , Knutson Mitchell D.
Published: February 2018

Significance

Manganese (Mn) is an essential nutrient that is toxic in excess. Exposure to excess Mn can result in Mn accumulation in the brain and neurological and motor disturbances resembling Parkinson disease. Here, we demonstrate that the transmembrane metal-ion transporter solute carrier family 39, member 14 (SLC39A14) is essential for Mn homeostasis. We provide evidence that SLC39A14 is required for efficient Mn uptake by the liver and pancreas, two organs that are known to actively participate in Mn excretion from the body. Accordingly, loss of SLC39A14 impairs Mn excretion, leading to Mn accumulation in the brain and most other extrahepatic tissues.
Slc39a14
-deficient mice, similar to
SLC39A14
-deficient human patients, display motor deficits, and thus offer a convenient model to study Mn/SLC39A14-related neurotoxicity.
Patient Predictors and Utilization of Health Services within a Medical Home for Homeless Persons
Authors: Jones Audrey L. , Thomas Roxanne , Hedayati Daniel O. , Saba Shaddy K. , Conley James , Gordon Adam J.
Published: February 2018

Background: The Veterans Health Administration (VHA) established a patient-centered medical home model of care for veterans experiencing homelessness called a Homeless Patient Aligned Care Team (HPACT) to improve engagement with primary care and reduce utilization of hospital-based services. To evaluate the impact of the HPACT model, this study compares the number and type of health care visits in the 12 months before and after enrollment in HPACT at one VHA facility, and explores patient characteristics associated with increases and decreases in visits. Methods: Chart reviews of VHA medical records were conducted for all patients enrolled in an HPACT in Pittsburgh, Pennsylvania, between May 2012 and December 2013 ( N = 179). Multivariable mixed-effect logistic regressions estimated differences in having any visit in the 0–6 months and 7–12 months before and after HPACT enrollment, and multinomial logistic regressions predicted increases or decreases versus no change in number of visits over 12 months. Results: Compared with 0–6 months prior to HPACT, patients were more likely to visit primary care in the 0–6 months (adjusted odds ratio [aOR] = 4.91, 95% confidence interval [CI] = 2.94–8.20) and 7–12 months (aOR = 2.30, 95% CI = 1.42–3.72) following HPACT. Patients were less likely to visit the emergency department (ED) or to be hospitalized in the 0–6 months (aOR = 0.57, 95% CI = 0.34–0.94; and aOR = 0.55, 95% CI = 0.25–0.76) and 7–12 months (aOR = 0.43, 95% CI = 0.33–0.91; and aOR = 0.45, 95% CI = 0.26–0.80) following HPACT. Patients were less likely to visit mental health (aOR = 0.35, 95% CI = 0.20–0.60) and addiction specialists (aOR = 0.39, 95% CI = 0.18–0.84) in the 7–12 months following HPACT. Overall, 59% of patients had increases in primary care visits following HPACT. Female patients and those with self-housing were less likely to have increases versus no change in primary care visits (adjusted relative risk ratio [aRRR] = 0.15, 95% CI = 0.03–0.74; and aRRR = 0.35, 95% CI = 0.14–0.90). Conclusions: An integrated HPACT model was successful in engaging homeless veterans in primary care for 1 year, potentially contributing to reductions in ED use. More tailored approaches may be needed for vulnerable populations experiencing homelessness, including homeless women.
Evaluation of creep rupture behaviour for weld joint and base metal of the Cr35Ni45Nb alloy
Authors: Guo Jingfeng , Cao Tieshan , Cheng Congqian , Meng Xianming , Zhao Jie
Published: February 2018

In order to investigate microstructure and creep rupture strength of a weld joint after aging, Cr35Ni45Nb alloy tubes were welded by the GTAW process of two-type filler metals. The tensile test, hardness and creep test were conducted to analyse the mechanical properties of the weld joint and base metal. The results show that the creep rupture time of the base metal at 1373 K is longer than a new weld joint, while the tensile properties of the base metal at room temperature are similar to a new weld joint. With aging, the microstructure of the weld metal and the base metal tended to be homogeneous, the creep rupture time of the weld joint improved and was similar to that of the base metal.
Repeated‐sprint performance and plasma responses following beetroot juice supplementation do not differ between recreational, competitive and elite sprint athletes
Authors: Jonvik K.L. , Nyakayiru J. , Van Dijk J.W. , Maase K. , Ballak S.B. , Senden J.M.G. , Van Loon L.J.C. , Verdijk L.B.
Published: February 2018

Purpose: There is an ongoing debate whether highly trained athletes are less responsive to the ergogenic properties of nitrate. We assessed the effects of nitrate supplementation on plasma nitrate and nitrite concentrations and repeated‐sprint performance in recreational, competitive and elite sprint athletes. Methods: In a randomized double‐blinded cross‐over design, recreational cyclists (n = 20), national talent speed‐skaters (n = 22) and Olympic‐level track cyclists (n = 10) underwent two 6‐day supplementation periods; 140 mL/d nitrate‐rich (BR; ∼800 mg/d) and nitrate‐depleted (PLA; ∼0.5 mg/d) beetroot juice. Blood samples were collected and three 30‐s Wingate tests were performed. Results: Plasma nitrate and nitrite concentrations were higher following BR vs PLA (P < .001), with no differences between sport levels (all P > .10). Peak power over the three Wingates was not different between BR and PLA (1338 ± 30 vs 1333 ± 30 W; P = .62), and there was no interaction between treatment (BR‐PLA) and Wingate number (1‐2‐3; P = .48). Likewise, mean power did not differ between BR and PLA (P = .86). In contrast, time to peak power improved by ∼2.8% following BR vs PLA (P = .007). This improvement in BR vs PLA was not different between Wingate 1, 2 and 3. Moreover, the effects of BR vs PLA did not differ between sport levels for any Wingate parameter (all P > .30). Conclusion: The plasma and repeated‐sprint performance responses to beetroot juice supplementation do not differ between recreational, competitive and elite sprint athletes. Beetroot juice supplementation reduces time to reach peak power, which may improve the capacity to accelerate during high‐intensity and sprint tasks in recreational as well as elite athletes.
Optimized RNP transfection for highly efficient CRISPR/Cas9-mediated gene knockout in primary T cells
Authors: Seki Akiko , Rutz Sascha
Published: February 2018

CRISPR (clustered, regularly interspaced, short palindromic repeats)/Cas9 (CRISPR-associated protein 9) has become the tool of choice for generating gene knockouts across a variety of species. The ability for efficient gene editing in primary T cells not only represents a valuable research tool to study gene function but also holds great promise for T cell–based immunotherapies, such as next-generation chimeric antigen receptor (CAR) T cells. Previous attempts to apply CRIPSR/Cas9 for gene editing in primary T cells have resulted in highly variable knockout efficiency and required T cell receptor (TCR) stimulation, thus largely precluding the study of genes involved in T cell activation or differentiation. Here, we describe an optimized approach for Cas9/RNP transfection of primary mouse and human T cells without TCR stimulation that results in near complete loss of target gene expression at the population level, mitigating the need for selection. We believe that this method will greatly extend the feasibly of target gene discovery and validation in primary T cells and simplify the gene editing process for next-generation immunotherapies.