bluuebunny/crossref_metadata_2025 huggingface dataset:
Total synthesis and stereochemical revision of xiamenmycin A
Authors: Jiao Xiaozhen , Yao Yangyang , Yang Beibei , Liu Xiaoyu , Li Xiaoyu , Yang Hongguang , Li Li , Xu Jun , Xu Minjuan , Xie Ping
Published: January 2016

The relative and absolute configurations of xiamenmycin A, a benzopyran compound isolated from Streptomyces xiamenensis 318 with a highly potent anti-fibrotic activity, have been characterized through the total synthesis.
Characterization of the nucleation precursor (H2SO4–(CH3)2NH) complex: intra-cluster interactions and atmospheric relevance
Authors: Ma Yan , Chen Jiao , Jiang Shuai , Liu Yi-Rong , Huang Teng , Miao Shou-Kui , Wang Chun-Yu , Huang Wei
Published: January 2016

Amines have been proposed to participate in the nucleation process, but the electron density analysis and the determination of a temperature dependence of the clusters are still lacking.
A novel strategy based on surfactant assisted electromembrane extraction for the determination of dicamba and 2,4-DB as model herbicides in real water samples
Authors: Bagheri Hasan , Fakhari Ali Reza , Sahragard Ali
Published: January 2016

Schematic illustration of the surfactant assisted electromembrane-extraction (SEME) technique.
Mechanism of the antioxidation effect of α-Fe2O3 on silicone rubbers at high temperature
Authors: Fei Hua-Feng , Han Xiaojie , Liu Bozheng , Gao Xiyin , Wang Qian , Zhang Zhijie , Xie Zemin
Published: January 2016

The high temperature resistance of silicone rubber (SR) could be significantly improved by adding hematite (α-Fe2O3).
Evaluation of the characteristics of non-oxidative biodiesels: a FAME composition, thermogravimetric and IR analysis
Authors: Shancita I. , Masjuki H. H. , Kalam M. A. , Reham S. S. , Ruhul A. M. , Monirul I. M.
Published: January 2016

Development and characterization of non-oxidative biodiesels for improvement of engine performance and exhaust emissions.
Engineering disorder into exotic electronic 2D TiO2nanosheets for enhanced photocatalytic performance
Authors: Yan Bo , Zhou Pengshang , Xu Qun , Zhou Xiaofang , Xu Dongdong , Zhu Jianhua
Published: January 2016

We successfully prepared exotic electronic 2D TiO2nanosheets and then engineered disorder into them to obtain black TiO2nanosheets.
Basicity and stability of urea deep eutectic mixtures
Authors: Simeonov S. P. , Afonso Carlos A. M.
Published: January 2016

Some decomposition occurs below 100 °C for urea based deep eutectic mixtures/solvents (DES) liberating ammonia and is enhanced for diols by formation of carbonates.
Phase transfer preparation of ultrasmall MnS nanocrystals with a high performance MRI contrast agent
Authors: Meng Jing , Zhao Yizhe , Li Zhongfeng , Wang Ligang , Tian Yang
Published: January 2016

In this paper, a phase transfer method is reported which was used to prepare ultrasmall manganese(ii) sulfide nanocrystals in which prefabricated MnS aggregations are transferred from cyclohexane into an aqueous solution of sodium citrate.
Comparison of different chemometric methods in quantifying total volatile basic-nitrogen (TVB-N) content in chicken meat using a fabricated colorimetric sensor array
Authors: Khulal Urmila , Zhao Jiewen , Hu Weiwei , Chen Quansheng
Published: January 2016

PSO-SVMR is an efficient chemometric tool to quantify TVB-N content in chicken.
Towards understanding the NTBphase: a combined experimental, computational and spectroscopic study
Authors: Ivšić Trpimir , Vinković Marijana , Baumeister Ute , Mikleušević Ana , Lesac Andreja
Published: January 2016

Combined studies support the hierarchical model for the NTBphase that involves formation of embryonic self-assembly of the propeller-shaped dimeric molecules withsyn-parallel orientation in the isotropic melt.
Synthesis of metapristone through an efficient N-demethylation of mifepristone
Authors: Wu Jianlei , Yu Xuemei , Liu Jian , Lin Yuqin , Gao Yu , Jia Lee , Chen Haijun
Published: January 2016

An improved and efficient condition of N-demethylation of mifepristone in an excellent yield is described.
Investigation of PDMS based bi-layer elasticity via interpretation of apparent Young's modulus
Authors: Sarrazin Baptiste , Brossard Rémy , Guenoun Patrick , Malloggi Florent
Published: January 2016

As the need of new methods for the investigation of thin films on various kinds of substrates becomes greater, a novel approach based on AFM nanoindentation is explored. In particular, a successful method for the investigation of thin layers on soft substrates is demonstrated.
Hydrogen bonding strength of diblock copolymers affects the self-assembled structures with octa-functionalized phenol POSS nanoparticles
Authors: Lu Yi-Syuan , Yu Chia-Yu , Lin Yung-Chih , Kuo Shiao-Wei
Published: January 2016

Hydrogen bonding strength on the self-assembled nanostructures formed from block copolymers of PS-b-P4VP, PS-b-P2VP and PS-b-PMMA with OP-POSS nanoparticles.
Biomimic hybrid polymer networks based on casein and poly(methacrylic acid). Case study: Ni2+removal
Authors: Spasojevic P. M. , Panic V. V. , Jovic M. D. , Markovic J. , van Roost C. , Popovic I. G. , Velickovic S. J.
Published: January 2016

Mimicking the excellence of natural materials presents an attractive route in the synthesis of advanced functional materials.
Correction: Spin-phonon coupling and high-temperature phase transition in multiferroic material YMnO3
Authors: Gupta Mayanak Kumar , Mittal Ranjan , Zbiri Mohamed , Sharma Neetika , Rols Stephane , Schober Helmut , Chaplot Samrath Lal
Published: January 2016

Correction for ‘Spin-phonon coupling and high-temperature phase transition in multiferroic material YMnO3’ by Mayanak Kumar Gupta et al., J. Mater. Chem. C, 2015, 3, 11717–11728.
ESCRT-III on endosomes: new functions, new activation pathway
Authors: Woodman Philip
Published: January 2016

The multivesicular body (MVB) pathway sorts ubiquitinated membrane cargo to intraluminal vesicles (ILVs) within the endosome, en route to the lysosomal lumen. The pathway involves the sequential action of conserved protein complexes [endosomal sorting complexes required for transport (ESCRTs)], culminating in the activation by ESCRT-II of ESCRT-III, a membrane-sculpting complex. Although this linear pathway of ESCRT activation is widely accepted, a study by Luzio and colleagues in a recent issue of the Biochemical Journal suggests that there is greater complexity in ESCRT-III activation, at least for some MVB cargoes. They show that ubiquitin-dependent sorting of major histocompatibility complex (MHC) class I to the MVB requires the central ESCRT-III complex but does not involve either ESCRT-II or functional links between ESCRT-II and ESCRT-III. Instead, they propose that MHC class I utilizes histidine-domain protein tyrosine phosphatase (HD-PTP), a non-canonical ESCRT interactor, to promote ESCRT-III activation.
Chaos time‐domain reflectometry for distributed diagnosis of complex topology wired networks
Authors: Auzanneau F.
Published: January 2016

A new reflectometry‐based wire diagnosis method using chaotic signals is presented. It shows excellent potential for the diagnosis of live wires (i.e. during their operational usage) and complex topology networks. The use of chaotic signals for distributed diagnosis and the detection of defects in wires is investigated. Chaos time‐domain Reflectometry (CTDR) using low auto‐correlation sidelobes signals, shows high performances in very noisy environment: the detection and location of hard defects are possible, even if several reflectometers inject their signals concurrently with the diagnosis and the normal operation of the cable. This enables using CTDR for distributed diagnosis of complex topology networks.
Postoperative Delayed Cervical Palsies: Understanding the Etiology
Authors: Planchard Ryan F. , Maloney Patrick R. , Mallory Grant W. , Puffer Ross C. , Spinner Robert J. , Nassr Ahmad , Fogelson Jeremy L. , Krauss William E. , Clarke Michelle J.
Published: January 2016

Study Design

Retrospective study.

Objective

This study reviews 1,768 consecutive cervical decompressions with or without instrumented fusion to identify patient-specific and procedural risk factors significantly correlated with the development of delayed cervical palsy (DCP).

Methods

Baseline demographic and procedural information was collected from the electronic medical record. Particular attention was devoted to reviewing each chart for recognized risk factors of postsurgical inflammatory neuropathy: autoimmune disease, blood transfusions, diabetes, and smoking.

Results

Of 1,669 patients, 56 (3.4%) developed a DCP. Although 71% of the palsies involved C5, 55% of palsies were multimyotomal and 18% were bilateral. Significant risk factors on univariate analysis included age ( p = 0.0061, odds ratio [OR] = 1.07, 95% confidence interval [CI] 1.008 to 1.050), posterior instrumented fusion ( p < 0.0001, OR = 3.30, 95% CI 1.920 to 5.653), prone versus semisitting/sitting position ( p = 0.0036, OR = 3.58, 95% CI 1.451 to 11.881), number of operative levels ( p < 0.0001, OR = 1.42, 95% CI 1.247 to 1.605), intraoperative transfusions ( p = 0.0231, OR = 2.57, 95% CI 1.152 to 5.132), and nonspecific autoimmune disease ( p = 0.0107, OR = 3.83, 95% CI 1.418 to 8.730). On multivariate analysis, number of operative levels ( p = 0.0053, OR = 1.27, 95% CI 1.075 to 1.496) and nonspecific autoimmune disease ( p = 0.0416, OR 2.95, 95% CI 1.047 to 7.092) remained significant.

Conclusions

Although this study partially supports a mechanical etiology in the pathogenesis of a DCP, we also describe a notable correlation with autoimmune risk factors. Bilateral and multimyotomal involvement provides additional support that some DCPs may result from an inflammatory response and thus an underlying multifactorial etiology for this complication.
Hawking radiation and classical tunneling: A ray phase space approach
Authors: Tracy E. R. , Zhigunov D.
Published: January 2016

Acoustic waves in fluids undergoing the transition from sub- to supersonic flow satisfy governing equations similar to those for light waves in the immediate vicinity of a black hole event horizon. This acoustic analogy has been used by Unruh and others as a conceptual model for “Hawking radiation.” Here, we use variational methods, originally introduced by Brizard for the study of linearized MHD, and ray phase space methods, to analyze linearized acoustics in the presence of background flows. The variational formulation endows the evolution equations with natural Hermitian and symplectic structures that prove useful for later analysis. We derive a 2 × 2 normal form governing the wave evolution in the vicinity of the “event horizon.” This shows that the acoustic model can be reduced locally (in ray phase space) to a standard (scalar) tunneling process weakly coupled to a unidirectional non-dispersive wave (the “incoming wave”). Given the normal form, the Hawking “thermal spectrum” can be derived by invoking standard tunneling theory, but only by ignoring the coupling to the incoming wave. Deriving the normal form requires a novel extension of the modular ray-based theory used previously to study tunneling and mode conversion in plasmas. We also discuss how ray phase space methods can be used to change representation, which brings the problem into a form where the wave functions are less singular than in the usual formulation, a fact that might prove useful in numerical studies.
Experimental study of transonic buffet phenomenon on a 3D swept wing
Authors: Dandois Julien
Published: January 2016

The objective of this paper is to analyze the 3D buffet phenomenon which appears on a swept wing at a high Mach number and/or high angle of attack. This aerodynamic instability induces strong wall pressure fluctuations and as such limits aircraft envelope. Consequently, it is interesting to understand this phenomenon in order to not only improve aircraft performance but also to provide more flexibility during the design phase. Results from two wind tunnel tests on a 3D half wing-body configuration are presented for several freestream Mach numbers (0.78–0.86) and Reynolds numbers (2.83 × 106–8.49 × 106, based on the aerodynamic mean chord). The buffet phenomenon is characterized using steady and unsteady wall pressure measurements. By opposition to the 2D buffet which exhibits rather a well marked peak in the pressure spectra, the 3D buffet is characterized by a broadband bump at a much higher Strouhal number (between 4 and 7 times higher). It is also observed that two different instabilities coexist on the suction side of the wing: the 3D buffet phenomenon (with Strouhal numbers ranging between 0.2 and 0.6) and the Kelvin-Helmholtz instability (with Strouhal numbers ranging between 1 and 4). Each phenomenon has a different Strouhal number but also different convection velocities and propagation directions.
On the relative rotational motion between rigid fibers and fluid in turbulent channel flow
Authors: Marchioli C. , Zhao L. , Andersson H. I.
Published: January 2016

In this study, the rotation of small rigid fibers relative to the surrounding fluid in wall-bounded turbulence is examined by means of direct numerical simulations coupled with Lagrangian tracking. Statistics of the relative (fiber-to-fluid) angular velocity, referred to as slip spin in the present study, are evaluated by modelling fibers as prolate spheroidal particles with Stokes number, St, ranging from 1 to 100 and aspect ratio, λ, ranging from 3 to 50. Results are compared one-to-one with those obtained for spherical particles (λ = 1) to highlight effects due to fiber length. The statistical moments of the slip spin show that differences in the rotation rate of fibers and fluid are influenced by inertia, but depend strongly also on fiber length: Departures from the spherical shape, even when small, are associated with an increase of rotational inertia and prevent fibers from passively following the surrounding fluid. An increase of fiber length, in addition, decouples the rotational dynamics of a fiber from its translational dynamics suggesting that the two motions can be modelled independently only for long enough fibers (e.g., for aspect ratios of order ten or higher in the present simulations).
Similarity and singularity in adhesive elastohydrodynamic touchdown
Authors: Carlson Andreas , Mahadevan L.
Published: January 2016

We consider the dynamics of an elastic sheet as it starts to adhere to a wall, a process that is limited by the viscous squeeze flow of the intervening liquid. Elastohydrodynamic lubrication theory allows us to derive a partial differential equation coupling the elastic deformation of the sheet, the microscopic van der Waals adhesion, and viscous thin film flow. We use a combination of numerical simulations of the governing equation and a scaling analysis to describe the self-similar touchdown of the sheet as it approaches the wall. An analysis of the equation in terms of similarity variables in the vicinity of the touchdown event shows that only the fundamental similarity solution is observed in the time-dependent numerical simulations, consistent with the fact that it alone is stable. Our analysis generalizes similar approaches for rupture in capillary thin film hydrodynamics and suggests experimentally verifiable predictions for a new class of singular flows linking elasticity, hydrodynamics, and adhesion.
Effect of advanced nanowire-based targets in nanosecond laser-matter interaction (invited)
Authors: Lanzalone G. , Altana C. , Mascali D. , Muoio A. , Malferrari L. , Odorici F. , Malandrino G. , Tudisco S.
Published: January 2016

An experimental campaign aiming to investigate the effects of innovative nanostructured targets based on Ag nanowires on laser energy absorption in the ns time domain has been carried out at the Laser Energy for Nuclear Science laboratory of INFN-LNS in Catania. The tested targets were realized at INFN-Bologna by anodizing aluminium sheets in order to obtain layers of porous Al2O3 of different thicknesses, on which nanowires of various metals are grown by electro-deposition with different heights. Targets were then irradiated by using a Nd:YAG laser at different pumping energies. Advanced diagnostic tools were used for characterizing the plasma plume and ion production. As compared with targets of pure Al, a huge enhancement (of almost two order of magnitude) of the X-ray flux emitted by the plasma has been observed when using the nanostructured targets, with a corresponding decrease of the “optical range” signal, pointing out that the energetic content of the laser produced plasma was remarkably increased. This analysis was furthermore confirmed from time-of-flight spectra.
Binding of ACE-inhibitors to in vitro and patient-derived amyloid-β fibril models
Authors: Bhavaraju Manikanthan , Phillips Malachi , Bowman Deborah , Aceves-Hernandez Juan M. , Hansmann Ulrich H. E.
Published: January 2016

Currently, no drugs exist that can prevent or reverse Alzheimer’s disease, a neurodegenerative disease associated with the presence, in the brain, of plaques that are composed of β-amyloid (Aβ) peptides. Recent studies suggest that angiotensin-converting enzyme (ACE) inhibitors, a set of drugs used to treat hypertension, may inhibit amyloid formation in vitro. In the present study, we investigate through computer simulations the binding of ACE inhibitors to patient-derived Aβ fibrils and contrast it with that of ACE inhibitors binding to in vitro generated fibrils. The binding affinities of the ACE inhibitors are compared with that of Congo red, a dye that is used to identify amyloid structures and that is known to be a weak inhibitor of Aβ aggregation. We find that ACE inhibitors have a lower binding affinity to the patient-derived fibrils than to in vitro generated ones. For patient-derived fibrils, their binding affinities are even lower than that of Congo red. Our observations raise doubts on the hypothesis that these drugs inhibit fibril formation in Alzheimer patients by interacting directly with the amyloids.
Dielectric structure design for microwave cloaking considering material properties
Authors: Heo Namjoon , Yoo Jeonghoon
Published: January 2016

To hide a metallic object from outside observers, we designed cloaking structures to manipulate the propagation path of the microwave at a specific frequency. Dielectric materials are used to realize the cloaking effect and their electromagnetic properties are evaluated to reduce the size of the cloaking structure as well as to take the loss effect into account. We used the structural design method based on the phase field method to control the electric field flow around a target object for cloaking. It is aimed to minimize the scattered electric field measured at the region located behind the target object for a normal incident wave in the X-band frequency range. Numerical examples are given to verify the suggested design process and its results.
Prospects of zero Schottky barrier height in a graphene-inserted MoS2-metal interface
Authors: Chanana Anuja , Mahapatra Santanu
Published: January 2016

A low Schottky barrier height (SBH) at source/drain contact is essential for achieving high drive current in atomic layer MoS2-channel-based field effect transistors. Approaches such as choosing metals with appropriate work functions and chemical doping are employed previously to improve the carrier injection from the contact electrodes to the channel and to mitigate the SBH between the MoS2 and metal. Recent experiments demonstrate significant SBH reduction when graphene layer is inserted between metal slab (Ti and Ni) and MoS2. However, the physical or chemical origin of this phenomenon is not yet clearly understood. In this work, density functional theory simulations are performed, employing pseudopotentials with very high basis sets to get insights of the charge transfer between metal and monolayer MoS2 through the inserted graphene layer. Our atomistic simulations on 16 different interfaces involving five different metals (Ti, Ag, Ru, Au, and Pt) reveal that (i) such a decrease in SBH is not consistent among various metals, rather an increase in SBH is observed in case of Au and Pt; (ii) unlike MoS2-metal interface, the projected dispersion of MoS2 remains preserved in any MoS2-graphene-metal system with shift in the bands on the energy axis. (iii) A proper choice of metal (e.g., Ru) may exhibit ohmic nature in a graphene-inserted MoS2-metal contact. These understandings would provide a direction in developing high-performance transistors involving heteroatomic layers as contact electrodes.
Electron injection for enhanced energy gain by a radially polarized laser pulse in vacuum in the presence of magnetic wiggler
Authors: Ghotra Harjit Singh , Kant Niti
Published: January 2016

We present a scheme of electron injection for enhanced electron energy gain by using a radially polarized (RP) laser pulse in vacuum under the influence of magnetic wiggler. The inherent symmetry of an RP laser pulse enforces the trapping and acceleration of electrons in the direction of propagation of laser pulse during laser electron interaction. A magnetic wiggler encircles the trajectory of accelerated electron and improves the strength of v→×B→ force which supports the retaining of betatron resonance for longer duration and leads to enhance electron acceleration. Four times higher electron energy is observed with a RP laser pulse of peak intensity 8.5×1020  W/cm2 in the presence of magnetic wiggler of 10.69 kG than that in the absence of magnetic wiggler. We have also analyzed the electron injection for enhanced energy gain and observe that the electron energy gain is relatively higher with a sideway injection than that of axial injection of electron. Injection angle δ is optimized and found that at δ=10° to the direction of propagation of laser pulse, maximum energy is obtained.
Measurement of toroidal vessel eddy current during plasma disruption on J-TEXT
Authors: Liu L. J. , Yu K. X. , Zhang M. , Zhuang G. , Li X. , Yuan T. , Rao B. , Zhao Q.
Published: January 2016

In this paper, we have employed a thin, printed circuit board eddy current array in order to determine the radial distribution of the azimuthal component of the eddy current density at the surface of a steel plate. The eddy current in the steel plate can be calculated by analytical methods under the simplifying assumptions that the steel plate is infinitely large and the exciting current is of uniform distribution. The measurement on the steel plate shows that this method has high spatial resolution. Then, we extended this methodology to a toroidal geometry with the objective of determining the poloidal distribution of the toroidal component of the eddy current density associated with plasma disruption in a fusion reactor called J-TEXT. The preliminary measured result is consistent with the analysis and calculation results on the J-TEXT vacuum vessel.
Existence of a virtual cathode close to a strongly electron emissive wall in low density plasmas
Authors: Tierno S. P. , Donoso J. M. , Domenech-Garret J. L. , Conde L.
Published: January 2016

The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows a phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.
Controlling system components with a sound card: A versatile inkjet fluid testing platform
Authors: Bognet Brice , Guo Yang , Ma Anson W. K.
Published: January 2016

In this paper, we demonstrate how to use a personal computer sound card to develop an experimental platform for evaluating the jettability and jetting behavior of inkjet fluids. The test fluid is driven out of a nozzle acoustically using a loudspeaker, forming a jet. The subsequent jet breakup process is then captured using a stroboscopic light source and a camera. Instead of using a delay generator as in previous work, the current setup uses a computer sound card and audio amplifier to (i) generate actuation waveforms of arbitrary shapes and (ii) synchronize the jet actuation and imaging with a time precision close to 5 μs. To correct for any signal distortions caused by the built-in high pass filters of the sound card and amplifier, a numerical filter is created and applied before sending the desired signal to the sound card. Such correction method does not require physically modifying the hardware of the sound card or amplifier and is applicable to different waveforms and filters provided that the transfer function is correctly identified. The platform has been tested using 20% (v/v) glycerol in water as a model fluid. Combining this platform with digital image analysis further enables a quantitative assessment of parameters such as the volumes and positions of the jet and drop that are important for quality control and development of new ink formulations.
Resonant tunneling assisted propagation and amplification of plasmons in high electron mobility transistors
Authors: Bhardwaj Shubhendu , Sensale-Rodriguez Berardi , Xing Huili Grace , Rajan Siddharth , Volakis John L.
Published: January 2016

A rigorous theoretical and computational model is developed for the plasma-wave propagation in high electron mobility transistor structures with electron injection from a resonant tunneling diode at the gate. We discuss the conditions in which low-loss and sustainable plasmon modes can be supported in such structures. The developed analytical model is used to derive the dispersion relation for these plasmon-modes. A non-linear full-wave-hydrodynamic numerical solver is also developed using a finite difference time domain algorithm. The developed analytical solutions are validated via the numerical solution. We also verify previous observations that were based on a simplified transmission line model. It is shown that at high levels of negative differential conductance, plasmon amplification is indeed possible. The proposed rigorous models can enable accurate design and optimization of practical resonant tunnel diode-based plasma-wave devices for terahertz sources, mixers, and detectors, by allowing a precise representation of their coupling when integrated with other electromagnetic structures.
Some considerations on the transport properties of water-glycerol suspensions
Authors: Mallamace Francesco , Corsaro Carmelo , Mallamace Domenico , Vasi Sebastiano , Vasi Cirino , Stanley H. Eugene
Published: January 2016

We study the self-diffusion coefficient and viscosity of a water-glycerol mixture for several glycerol molar fractions as a function of temperature well inside the metastable supercooled regime. We perform NMR experiments and verify that the system has at different concentration a fragile-to-strong crossover accompanied by the violation of the Stokes-Einstein relation. We observe that the crossover temperature depends on the water amount. Studying the fractional representation of the Stokes-Einstein relation, we find that in these systems dynamical arrest does not exhibit criticality and the transport parameters have a universal behavior.
In situ surface/interface x-ray diffractometer for oxide molecular beam epitaxy
Authors: Lee J. H. , Tung I. C. , Chang S.-H. , Bhattacharya A. , Fong D. D. , Freeland J. W. , Hong Hawoong
Published: January 2016

In situ studies of oxide molecular beam epitaxy by synchrotron x-ray scattering has been made possible by upgrading an existing UHV/molecular beam epitaxy (MBE) six-circle diffractometer system. For oxide MBE growth, pure ozone delivery to the chamber has been made available, and several new deposition sources have been made available on a new 12 in. CF (ConFlat, a registered trademark of Varian, Inc.) flange. X-ray diffraction has been used as a major probe for film growth and structures for the system. In the original design, electron diffraction was intended for the secondary diagnostics available without the necessity of the x-ray and located at separate positions. Deposition of films was made possible at the two diagnostic positions. And, the aiming of the evaporation sources is fixed to the point between two locations. Ozone can be supplied through two separate nozzles for each location. Also two separate thickness monitors are installed. Additional features of the equipment are also presented together with the data taken during typical oxide film growth to illustrate the depth of information available via in situ x-ray techniques.
Improvement in Jc performance below liquid nitrogen temperature for SmBa2Cu3Oy superconducting films with BaHfO3 nano-rods controlled by low-temperature growth
Authors: Miura S. , Yoshida Y. , Ichino Y. , Xu Q. , Matsumoto K. , Ichinose A. , Awaji S.
Published: January 2016

For use in high-magnetic-field coil-based applications, the critical current density (Jc) of REBa2Cu3Oy (REBCO, where RE = rare earth) coated conductors must be isotropically improved, with respect to the direction of the magnetic field; these improvements must be realized at the operating conditions of these applications. In this study, improvement of the Jc for various applied directions of magnetic field was achieved by controlling the morphology of the BaHfO3 (BHO) nano-rods in a SmBCO film. We fabricated the 3.0 vol. % BHO-doped SmBCO film at a low growth temperature of 720 °C, by using a seed layer technique (Ts = 720 °C film). The low-temperature growth resulted in a morphological change in the BHO nano-rods. In fact, a high number density of (3.1 ± 0.1) × 103 μm−2 of small (diameter: 4 ± 1 nm), discontinuous nano-rods that grew in various directions, was obtained. In Jc measurements, the Jc of the Ts = 720 °C film in all directions of the applied magnetic field was higher than that of the non-doped SmBCO film. The Jcmin (6.4 MA/cm2) of the former was more than 6 times higher than that (1.0 MA/cm2) of the latter at 40 K, under 3 T. The aforementioned results indicated that the discontinuous BHO nano-rods, which occurred with a high number density, exerted a 3D-like flux pinning at the measurement conditions considered. Moreover, at 4.2 K and under 17 T, a flux pinning force density of 1.6 TN/m3 was realized; this value was comparable to the highest value recorded, to date.
Coarsening dynamics of ice crystals intercalated between graphene and supporting mica
Authors: Bampoulis Pantelis , Lohse Detlef , Zandvliet Harold J. W. , Poelsema Bene
Published: January 2016

The effect of humidity on intercalated water between exfoliated graphene and mica has been previously reported. At low humidity, epitaxial one-layer thick ice fractals form. The growth of the ice fractal is initiated by the heat extracted from the system by evaporation, into the 3D ambient, of the second layer of water intercalated between mica and graphene under low humidity conditions. Here, we study the fractal shape dependence on the graphene cover and the evaporation rate of the water molecules from the double bilayer. We found that the thickness of the fractals' fingers scale as the square root of the ratio of the bending energy of graphene plus the surface energy of the intercalated ice and the product of the velocity of the fractal front and a term related to hindrance of the water ad-molecules. Ice fractals formed under a thick graphene cover and upon a low evaporation rate are thick with few side branches, whereas fractals grown upon high growth rate under single-layer graphene are thin and very ramified. We attribute the coarsening of fractals to the extra degree of freedom of the surrounding water molecules, enabled by the non-complete adaptation of the ice crystal's morphology by the graphene cover.
High harmonic terahertz confocal gyrotron with nonuniform electron beam
Authors: Fu Wenjie , Guan Xiaotong , Yan Yang
Published: January 2016

The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonic confocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.
Study of toroidal flow generation by ion cyclotron range of frequency minority heating in the Alcator C-Mod plasma
Authors: Murakami S. , Itoh K. , Zheng L. J. , Van Dam J. W. , Bonoli P. , Rice J. E. , Fiore C. L. , Gao C. , Fukuyama A.
Published: January 2016

The averaged toroidal flow of energetic minority ions during ICRF (ion cyclotron range of frequencies) heating is investigated in the Alcator C-Mod plasma by applying the GNET code, which can solve the drift kinetic equation with complicated orbits of accelerated energetic particles. It is found that a co-directional toroidal flow of the minority ions is generated in the region outside of the resonance location, and that the toroidal velocity reaches more than 40% of the central ion thermal velocity (Vtor ∼ 300 km/s with PICRF ∼ 2 MW). When we shift the resonance location to the outside of |r/a|∼0.5, the toroidal flow immediately inside of the resonance location is reduced to 0 or changes to the opposite direction, and the toroidal velocity shear is enhanced at r/a ∼ 0.5. A radial diffusion equation for toroidal flow is solved by assuming a torque profile for the minority ion mean flow, and good agreements with experimental radial toroidal flow profiles are obtained. This suggests that the ICRF driven minority ion flow is related to the experimentally observed toroidal rotation during ICRF heating in the Alcator C-Mod plasma.
Experimental verification of the capillary plasma triggered long spark gap under the extremely low working coefficient in air
Authors: Huang D. , Yang L. J. , Huo P. , Ma J. B. , Liu S. , Wang W. , Ding W. D. , Li G. , Yao S. L.
Published: January 2016

The paper has proposed a new triggering method for long spark gap based on capillary plasma ejection and conducted the experimental verification under the extremely low working coefficient, which represents that the ratio of the spark gap charging voltage to the breakdown voltage is particularly low. The quasi-neutral plasma is ejected from the capillary and develops through the axial direction of the spark gap. The electric field in the spark gap is thus changed and its breakdown is incurred. It is proved by the experiments that the capillary plasma ejection is effective in triggering the long spark gap under the extremely low working coefficient in air. The study also indicates that the breakdown probabilities, the breakdown delay, and the delay dispersion are all mainly determined by the characteristics of the ejected plasma, including the length of the plasma flow, the speed of the plasma ejection, and the ionization degree of the plasma. Moreover, the breakdown delay and the delay dispersion increase with the length of the long spark gap, and the polarity effect exists in the triggering process. Lastly, compared with the working patterns of the triggering device installed in the single electrode, the working pattern of the devices installed in both the two electrodes, though with the same breakdown process, achieves the ignition under longer gap distance. To be specific, at the gap length of 14 cm and the working coefficient of less than 2%, the spark gap is still ignited accurately.
Confinement and diffusion modulate bistability and stochastic switching in a reaction network with positive feedback
Authors: Mlynarczyk Paul J. , Pullen Robert H. , Abel Steven M.
Published: January 2016

Positive feedback is a common feature in signal transduction networks and can lead to phenomena such as bistability and signal propagation by domain growth. Physical features of the cellular environment, such as spatial confinement and the mobility of proteins, play important but inadequately understood roles in shaping the behavior of signaling networks. Here, we use stochastic, spatially resolved kinetic Monte Carlo simulations to explore a positive feedback network as a function of system size, system shape, and mobility of molecules. We show that these physical properties can markedly alter characteristics of bistability and stochastic switching when compared with well-mixed simulations. Notably, systems of equal volume but different shapes can exhibit qualitatively different behaviors under otherwise identical conditions. We show that stochastic switching to a state maintained by positive feedback occurs by cluster formation and growth. Additionally, the frequency at which switching occurs depends nontrivially on the diffusion coefficient, which can promote or suppress switching relative to the well-mixed limit. Taken together, the results provide a framework for understanding how confinement and protein mobility influence emergent features of the positive feedback network by modulating molecular concentrations, diffusion-influenced rate parameters, and spatiotemporal correlations between molecules.
Effective g-factors of carriers in inverted InAs/GaSb bilayers
Authors: Mu Xiaoyang , Sullivan Gerard , Du Rui-Rui
Published: January 2016

We perform tilt-field transport experiment on inverted InAs/GaSb, which hosts quantum spin Hall insulator. By means of coincidence method, Landau level (LL) spectra of electron and hole carriers are systematically studied at different carrier densities tuned by gate voltages. When Fermi level stays in the conduction band, we observe LL crossing and anti-crossing behaviors at odd and even filling factors, respectively, with a corresponding g-factor of 11.5. It remains nearly constant for varying filling factors and electron densities. On the contrary, for GaSb holes, only a small Zeeman splitting is observed even at large tilt angles, indicating a g-factor of less than 3.
Dynamics of spallation during femtosecond laser ablation studied by time-resolved reflectivity with double pump pulses
Authors: Kumada Takayuki , Otobe Tomohito , Nishikino Masaharu , Hasegawa Noboru , Hayashi Terutake
Published: January 2016

The dynamics of photomechanical spallation during femtosecond laser ablation of fused silica was studied by time-resolved reflectivity with double pump pulses. Oscillation of reflectivity was caused by interference between the probe pulses reflected at the sample surface and the spallation layer, and was enhanced when the surface was irradiated with the second pump pulse within a time interval, Δτ, of several picoseconds after the first pump pulse. However, as Δτ was increased, the oscillation amplitude decreased with an exponential decay time of 10 ps. The oscillation disappeared when Δτ exceeded 20 ps. This result suggests that the formation time of the spallation layer is approximately 10 ps. A second pump pulse with Δτ shorter than 10 ps excites the bulk sample. The spallation layer that is photo-excited by the first and second pump pulses is separated afterward. In contrast, a pulse with Δτ longer than the formation time excites and breaks up the spallation layer that has already been separated from the bulk. The formation time of the spallation layer, as determined in this experiment, is attributed to the characteristic time of the mechanical equilibration corresponding to the thickness divided by the sound velocity of the photo-excited layer.
Heat conduction in multifunctional nanotrusses studied using Boltzmann transport equation
Authors: Dou Nicholas G. , Minnich Austin J.
Published: January 2016

Materials that possess low density, low thermal conductivity, and high stiffness are desirable for engineering applications, but most materials cannot realize these properties simultaneously due to the coupling between them. Nanotrusses, which consist of hollow nanoscale beams architected into a periodic truss structure, can potentially break these couplings due to their lattice architecture and nanoscale features. In this work, we study heat conduction in the exact nanotruss geometry by solving the frequency-dependent Boltzmann transport equation using a variance-reduced Monte Carlo algorithm. We show that their thermal conductivity can be described with only two parameters, solid fraction and wall thickness. Our simulations predict that nanotrusses can realize unique combinations of mechanical and thermal properties that are challenging to achieve in typical materials.
Band gap engineering of a soft inorganic compound PbI2 by incommensurate van der Waals epitaxy
Authors: Wang Yiping , Sun Yi-Yang , Zhang Shengbai , Lu Toh-Ming , Shi Jian
Published: January 2016

Van der Waals epitaxial growth had been thought to have trivial contribution on inducing substantial epitaxial strain in thin films due to its weak nature of van der Waals interfacial energy. Due to this, electrical and optical structure engineering via van der Waals epitaxial strain has been rarely studied. In this report, we show that significant band structure engineering could be achieved in a soft thin film material PbI2 via van der Waals epitaxy. The thickness dependent photoluminescence of single crystal PbI2 flakes was studied and attributed to the substrate-film coupling effect via incommensurate van der Waals epitaxy. It is proposed that the van der Waals strain is resulted from the soft nature of PbI2 and large van der Waals interaction due to the involvement of heavy elements. Such strain plays vital roles in modifying the band gap of PbI2. The deformation potential theory is used to quantitatively unveil the correlation between thickness, strain, and band gap change. Our hypothesis is confirmed by the subsequent mechanical bending test and Raman characterization.
Evaluating conducting network based transparent electrodes from geometrical considerations
Authors: Kumar Ankush , Kulkarni G. U.
Published: January 2016

Conducting nanowire networks have been developed as viable alternative to existing indium tin oxide based transparent electrode (TE). The nature of electrical conduction and process optimization for electrodes have gained much from the theoretical models based on percolation transport using Monte Carlo approach and applying Kirchhoff's law on individual junctions and loops. While most of the literature work pertaining to theoretical analysis is focussed on networks obtained from conducting rods (mostly considering only junction resistance), hardly any attention has been paid to those made using template based methods, wherein the structure of network is neither similar to network obtained from conducting rods nor similar to well periodic geometry. Here, we have attempted an analytical treatment based on geometrical arguments and applied image analysis on practical networks to gain deeper insight into conducting networked structure particularly in relation to sheet resistance and transmittance. Many literature examples reporting networks with straight or curvilinear wires with distributions in wire width and length have been analysed by treating the networks as two dimensional graphs and evaluating the sheet resistance based on wire density and wire width. The sheet resistance values from our analysis compare well with the experimental values. Our analysis on various examples has revealed that low sheet resistance is achieved with high wire density and compactness with straight rather than curvilinear wires and with narrower wire width distribution. Similarly, higher transmittance for given sheet resistance is possible with narrower wire width but of higher thickness, minimal curvilinearity, and maximum connectivity. For the purpose of evaluating active fraction of the network, the algorithm was made to distinguish and quantify current carrying backbone regions as against regions containing only dangling or isolated wires. The treatment can be helpful in predicting the properties of a network simply from image analysis and will be helpful in improvisation and comparison of various TEs and better understanding of electrical percolation.
Electronic structure of antimonene grown on Sb2Te3 (111) and Bi2Te3 substrates
Authors: Lei Tao , Liu Chen , Zhao Jia-Li , Li Jin-Mei , Li Ya-Ping , Wang Jia-Ou , Wu Rui , Qian Hai-Jie , Wang Hui-Qiong , Ibrahim Kurash
Published: January 2016

We explore the formation of single bilayer Sb(111) ultrathin film (Antimonene) on Bi2Te3 and Sb2Te3 substrates for the first time, which is theoretically predicated to be a robust trivial semiconductor but can be tuned to a 2D TI by reducing the buckling height. From angle-resolved photoemission spectroscopy measurements, the antimonene can be well grown on the two surfaces and shows clear band dispersion. The electronic structure of the antimonene shows similar character on the two surfaces, but due to the interfacial strain effect, the bands of antimonene on Bi2Te3 are flatter than on Sb2Te3, which attributes to Bi2Te3 substrate lattice constants lager than Sb2Te3. At the same time, the charge transfer effect is also observed through core level shift, which influences the band dispersion simultaneously.
Cryogenic resonant microwave compressors with energy extraction through “warm” interference switches
Authors: Artemenko S. N. , Samoilenko G. M. , Shlapakovski A. S. , Yushkov Yu. G.
Published: January 2016

A method of switching cryogenic resonant microwave compressors from the energy accumulation mode to the energy release mode is proposed and analyzed. The switching process is based on the resonant transfer of the microwave energy from a cryogenic storage cavity to a room temperature commutation cavity. The transfer can be realized using a cascade interference microwave switch weakly coupled to the storage cavity and consisting of two H-plane waveguide tees connected in series. The tees are made of a normally conducting material, located outside the cryostat, and contain commuting units in shorted side arms. The length of the cascade input arm (from the storage cavity to the first tee) is non-resonant, while the space between the storage cavity and the second tee is resonant. The weak coupling of the storage cavity to the cascade and the non-resonant length of its input arm allow one to minimize losses during the energy accumulation phase. When the commuting unit in the first tee is ignited, the tee opens, and the non-resonant volume of the cascade input arm is transformed into the volume of the resonant commutation cavity. The microwave energy is then transferred in a resonant way from the storage cavity to the commutation cavity, and when the transfer is complete, the commuting unit in the second tee is ignited to extract the energy into a load. It is shown analytically that, at a certain value of the coupling (the cryogenic storage cavity to the normally conducting cascade of tees) and length of the cascade input arm, the power gain in the storage cavity can be kept high. It is also shown that the energy accumulated in the storage cavity can be effectively transferred to the commutation cavity and from the commutation cavity to the load.