bluuebunny/crossref_metadata_2025 huggingface dataset:
Re-evaluating the role of phosphinic acid (DINHOP) adsorption at the photoanode surface in the performance of dye-sensitized solar cells
Authors: Rodríguez-Perez Manuel , Noh-Pat Felipe , Romero-Contreras Alfredo , Reyes-Ramírez Emigdio J. , Krishnan Siva Kumar , Ortíz-Quiñonez Jose L. , Alvarado Joaquín , Pal Umapada , Olalde-Velasco Paul , Villanueva-Cab Julio
Published: December 2019

Dineohexyl phosphinic acid (DINHOP) is a popular amphiphilic molecular insulator considered as the most efficient co-adsorbent (co-grafter) for the improvement of the photovoltaic performance of TiO2 based hybrid solar cells.
The synergistic role of the support surface and Au–Cu alloys in a plasmonic Au–Cu@LDH photocatalyst for the oxidative esterification of benzyl alcohol with methanol
Authors: Wang Xiaoyu , Wang Ruiyi , Wang Jie , Fan Chaoyang , Zheng Zhanfeng
Published: December 2019

The acid–base pairs of the support synergistic with Au–Cu alloy NPs could drive the oxidative esterification of benzyl alcohol with methanol.
Strong Lewis acidic catalysts for C–F bond activation by fluorination of activated γ-Al2O3
Authors: Marshall Clara Patricia , Scholz Gudrun , Braun Thomas , Kemnitz Erhard
Published: December 2019

A strong solid Lewis acid catalyst has been successfully obtained by modifying a known procedure of fluorinating γ-aluminium oxide, which was pre-calcined under vacuum.
Behavior, mechanism and equilibrium studies of Au(iii) extraction with an ionic liquid [C4-6-C4BIm]Br2
Authors: Su Hongmei , Wang Qi , Wang Ning , Yang Yanzhao
Published: December 2019

The first gemini-type benzimidazole ionic liquid ([C4-6-C4BIm]Br2) with two sites of action was synthesized and applied for gold extraction.
High-sensitivity dual UV/NIR-excited luminescence thermometry by rare earth vanadate nanoparticles
Authors: Perrella Rafael Vieira , de Sousa Filho Paulo Cesar
Published: December 2019

High-crystallinity Ln3+-doped YVO4 nanoparticles combine multiple emissions under dual UV/NIR excitation, promoting high performance self-referenced luminescence thermometry.
Emerging investigator series: polymeric nanocarriers for agricultural applications: synthesis, characterization, and environmental and biological interactions
Authors: Shakiba Sheyda , Astete Carlos E. , Paudel Sachin , Sabliov Cristina M. , Rodrigues Debora F. , Louie Stacey M.
Published: December 2019

This review discusses polymeric nanocarriers for agrochemical delivery, from synthesis, characterization, and release, to benefits for agrochemical efficiency and sustainability.
Impact of calcium levels on lipid digestion and nutraceutical bioaccessibility in nanoemulsion delivery systems studied using standardized INFOGEST digestion protocol
Authors: Tan Yunbing , Li Ruyi , Zhou Hualu , Liu Jinning , Muriel Mundo Jorge , Zhang Ruojie , McClements David Julian
Published: December 2019

The bioaccessibility of hydrophobic bioactives may be greatly reduced in the presence of calcium.
Chitosan reduces vitamin D bioaccessibility in food emulsions by binding to mixed micelles
Authors: Tan Yunbing , Li Ruyi , Liu Chengzhen , Muriel Mundo Jorge , Zhou Hualu , Liu Jinning , McClements David Julian
Published: December 2019

Consumption of sufficiently high quantities of dietary fibers has been linked to a range of health benefits.
Metagenomic analysis of gut microbiota modulatory effects of jujube (Ziziphus jujuba Mill.) polysaccharides in a colorectal cancer mouse model
Authors: Ji Xiaolong , Hou Chunyan , Gao Yonggang , Xue Yuqiang , Yan Yizhe , Guo Xudan
Published: December 2019

Accumulating evidence has reported that the gut microbiota could play important roles in the occurrence and progression of colorectal cancer.
Precise measurement of selenium isotopes by HG-MC-ICPMS using a 76–78 double-spike
Authors: Pons Marie-Laure , Millet Marc-Alban , Nowell Geoff N. , Misra Sambuddha , Williams Helen M.
Published: December 2019

A novel 76Se–78Se double spike allows for rapid and precise selenium isotope measurements in geological samples.
Shape- and size dependent piezoelectric properties of monolayer hexagonal boron nitride nanosheets
Authors: Nan Yang , Tan Dan , Zhao Junqi , Willatzen Morten , Wang Zhong Lin
Published: December 2019

A symmetry analysis of 2D BN nanosheet geometries is carried out. We demonstrate effective shape tuning of piezoelectric properties.
Dithienothiazine dimers, trimers and polymers – novel electron-rich donors with red-shifted luminescence
Authors: Nau Jennifer , Schneeweis Arno P. W. , Müller Thomas J. J.
Published: December 2019

Dithienothiazine oligomers and polymers display significant red shifted luminescence and low oxidation potentials.
Application of graphene derivatives and their nanocomposites in tribology and lubrication: a review
Authors: Sun Jianlin , Du Shaonan
Published: December 2019

Recent studies have found that other forms of graphene derivatives perform better in tribological and lubricating applications. This paper reviews the research progress of graphene derivatives and their nanocomposites in tribology and lubrication.
Visible-light photocatalytic capability and the mechanism investigation of a novel PANI/Sn3O4 p–n heterostructure
Authors: Lv Manfei , Yang Liuqing , Wang Xiangliang , Cheng Xinlei , Song Yan , Yin Yinkun , Liu Huimin , Han Yongjun , Cao Kesheng , Ma Wei , Qi Guang , Li Songtian
Published: December 2019

A novel polyaniline (PANI)/Sn3O4 heterojunction composed of PANI nanofibers and Sn3O4 nanosheets was fabricated by a facile physical milling technique.
Nitrogen-doped hierarchical porous CNF derived from fibrous structured hollow ZIF-8 for a high-performance supercapacitor electrode
Authors: Nie Hongjiao , Mi Kan , Song Lanlan , Zheng Xiuwen
Published: December 2019

Hollow ZIF-8 shells were assembled into fibers to obtain nitrogen-doped hierarchical porous carbon nanofibers for excellent supercapacitor application.
Remarkably enhanced performance of the metathesis reaction of ethylene and 1-butene to propene using one-step prepared W-MCM-41 catalysts
Authors: Wang Changji , Jiang Feng , Zuo Guangzheng , Liu Bing , Li Hanxu , Liu Xiaohao
Published: December 2019

The W-MCM-41 catalysts synthesized via one-step precipitation method showed the excellent activity and selectivity for the metathesis reaction of ethylene and 1-butene to propene.
Predicting viable isomers of [X,C,N] and [H,X,C,N] (X = Sn, Pb)
Authors: Sun Yu-Wang , Wang Hai-Yan , Ding Yi-Hong
Published: December 2019

Two new metal cyanide/isocyanide and hydrometal cyanide/isocyanide compounds of Sn and Pb were studied to assist their interstellar detection.
Higher integrability for the gradient of Mumford-Shahalmost-minimizers
Authors: Piontek Sebastian , Schmidt Thomas
Published: December 2019

We extend a recent higher-integrability result for the gradient of minimizers of the Mumford-Shah functional to a suitable class of almost-minimizers. The extension crucially depends on an L∞gradient estimate up to regular portions of the discontinuity set of an almost-minimizer.
On L∞ stabilization of diagonal semilinear hyperbolic systems by saturated boundary control
Authors: Dus Mathias , Ferrante Francesco , Prieur Christophe
Published: December 2019

This paper considers a diagonal semilinear system of hyperbolic partial differential equations with positive and constant velocities. The boundary condition is composed of an unstable linear term and a saturated feedback control. Weak solutions with initial data in L2([0, 1]) are considered and well-posedness of the system is proven using nonlinear semigroup techniques. Local L∞ exponential stability is tackled by a Lyapunov analysis and convergence of semigroups. Moreover, an explicit estimation of the region of attraction is given.
Spectra of operator pencils with small 𝒫𝒯-symmetric periodic perturbation
Authors: Borisov Denis , Cardone Giuseppe
Published: December 2019

We study the spectrum of a quadratic operator pencil with a small 𝒫𝒯-symmetric periodic potential and a fixed localized potential. We show that the continuous spectrum has a band structure with bands on the imaginary axis separated by usual gaps, while on the real axis, there are no gaps but at certain points, the bands bifurcate into small parabolas in the complex plane. We study the isolated eigenvalues converging to the continuous spectrum. We show that they can emerge only in the aforementioned gaps or in the vicinities of the small parabolas, at most two isolated eigenvalues in each case. We establish sufficient conditions for the existence and absence of such eigenvalues. In the case of the existence, we prove that these eigenvalues depend analytically on a small parameter and we find the leading terms of their Taylor expansions. It is shown that the mechanism of the eigenvalue emergence is different from that for small localized perturbations studied in many previous works.
Optimal control on graphs: existence, uniqueness, and long-term behavior
Authors: Guéant Olivier , Manziuk Iuliia
Published: December 2019

The literature on continuous-time stochastic optimal control seldom deals with the case of discrete state spaces. In this paper, we provide a general framework for the optimal control of continuous-time Markov chains on finite graphs. In particular, we provide results on the long-term behavior of value functions and optimal controls, along with results on the associated ergodic Hamilton-Jacobi equation.
Plastic Flow in a Thin Layer: New Formulation of the Boundary-Value Problem and Its Solution
Authors: Kadymov Vagid , Sosenushkin Eugenе
Published: December 2019

The paper is dedicated to the theory of flow in a thin plastic layer that has numerous applications in calculations of technological processes of material treatment by pressure, such as stamping and pressing of thin-walled structural elements, thin-sheet rolling, and others. Two-dimensional, averaged over the thickness of the layer mathematical formulation of the contact boundary value problem of the spreading of a plastic layer on the plane has been examined. In the framework of the general “viscous liquid” model, an approximate analytical solution has been obtained and evaluated against measurements. This solution is in good agreement with the experimental results in the area far from the free boundary and the central part of the sample.
Mathematical Modeling of Multi-Element Antenna Arrays with Chiral Metamaterials Substrates Using Singular Integral Equations
Authors: Klyuev Dmitriy , Neshcheret Anatoly , Osipov Oleg , Potapov Aleksandr
Published: December 2019

In this paper, a physical model of the multi-element antenna arrays (MEAA) has been considered and a self-consistent numerical method for solving the problem of current distribution on the MEAA surface with chiral metamaterials substrate has been proposed. The algorithm of the input admittance matrix elements for chiral layer based on the conductive left and right-handed helices has been developed and elements of the matrix surface impedances for investigated structures have been found. A set of singular integral equations with a Cauchy kernel for calculating the current density on the surface of the MEAA has been derived. A numerical solution of the set is a well-posed in the sense of Hadamard. Calculations of current distribution on the MEAA surface, impedance characteristics of a three-element antenna array and the dependence of the isolation levels between emitters on the chirality parameter have been performed and analysed. It has been shown that the use of chiral substrates can substantially increase the isolation between emitters.
Development of the Effective Reaction Model for Diamond Deposition Simulation within the Continuous Media Approach
Authors: Leshchev Dmitry V. , Gorbachev Yuriy E.
Published: December 2019

Three models for diamond growth process by the chemical vapor deposition of methane are proposed. They differ in the degree of detail of the surface reaction description. The most complete model contains the reactions of deposition, etching and insertion. Gas-dynamic simulations have been performed for all those models. The species delivery to the substrate and the contribution from different species to the growth process is analysed. It is shown that different surface reaction models lead to different profiles of the species concentrations in the immediate vicinity of the substrate, thus, the experimental data on the growth rate may give information on the growth mechanism.
Hydrogen Spillover Mechanisms over a Graphite Surface
Authors: Leshchev Dmitry V.
Published: December 2019

Four different mechanisms of hydrogen spillower over carbon surface are considered in the framework of a single quantum-chemical approach. Two of them, described in the literature, are the physical migration of a bonded hydrogen atom along the surface and the edge of the graphene. One of the mechanisms proposed by the author does not include the migration of atomic hydrogen, but is realized via a transfer of carbon radical over a carbon sheet and generation of H atom in another place. Calculated activation energies of all four mechanisms are compared.
Non-Isothermal Compositional Model for Simulation of Multiphase Porous Media Flows
Authors: Trapeznikova Marina , Churbanova Natalia , Lyupa Anastasia
Published: December 2019

The research carried out in this work is aimed at the development of an explicit computational algorithm to simulate non-isothermal flow of multiphase multicomponent slightly compressible fluid through porous media. Such a modeling is necessary, for example, at solving practically important problems of hydrocarbon recovery via thermal methods and contaminated soil remediation via the hot steam injection. The original model and algorithm developed by the authors earlier draw the analogy with the quasi-gas-dynamic set of equations. Phase continuity equations were modified to get regularizing terms, while the type of equations was changed from parabolic to hyperbolic for the approximation by an explicit scheme with a mild enough stability condition. Since an adequate description of temperature-dependent porous media processes requires an explicit consideration of the transfer of mass and energy between the phases, the present work focuses on the generalization of the proposed approach to the case of multicomponent composition of fluids. Conservation laws are currently formulated for the components in terms of the mass concentrations of components in the phases. Constants of the phase equilibrium were used to close the set of equations. The developed model and algorithm have been verified numerically via test predictions of twoand three-phase flows, and, the phase transition of water into the gas phase at heating has been reproduced correctly.
Earth as a Gravitational-Wave Interferometr
Authors: Il’chenko Vadim
Published: December 2019

Based on the principle of Equivalence of Gravitating Masses (EGM) and tectonostratigraphic model of the Earth outer shell structure (the Earth crust and upper mantle), the average depth of the lunar mass gravitational influence on the Earth was calculated as ~1600 km. The developed model is based on the mechanism of rocks tectonic layering of the Earth crust-mantle shell as an oscillatory system with dynamic conditions of a standing wave, regularly excited by the lunar tide and immediately passing into the damping mode. After comparing the average depth of solid lunar tide impact of ~1600 km with the height of the solid lunar tide “hump” on the Earth surface of 0.5 m, a “tensile strain” was calculated with an amplitude only one order of magnitude larger than the amplitude of the gravitational wave recorded by the Advanced LIGO interferometer: A≈10-18 m (the merger result of a black holes pair ca 1.3 Ga ago). The results of the present study suggest that the crust-mantle shell of the Earth may be used as a gravitational-wave interferometer.
Restoration of the Lost Map Area of the Underlying Image Surface Using the Reconstruction Method
Authors: Ibadov Ragim , Fedosov Valentine , Ibadov Samir , Gapon Nikolay , Sizyakin Roman
Published: December 2019

The article presents a method for recovering lost sections of the map of the underlying surface. We consider spatial autocorrelation as image pre-processing for its subsequent analysis when restoring a part of the map in the direction of the radar carrier course. An algorithm for recovering images of lost areas has been proposed and a software implementing the algorithm has been developed. The efficiency of the developed algorithm has been evaluated on a test set of images using a statistical criterion.
Solution of the Problem of Smoothing of the Signals at the Preprocessing of Thermal Images
Authors: Semenishchev Evgenii , Tolstova Irina , Gavlicky Aleksandr , Cen Yigang
Published: December 2019

Smoothing two-dimensional digital signals is important for a number of applications. The paper presents a mathematical method and an algorithm for smoothing two-dimensional digital signals. The method is based on minimizing the objective function using criteria of the first-order finite difference between the rows and columns of the image as a measure of distance. To estimate the parameters of the developed method, a non-iterative algorithm is used. The present study shows results of changing the smoothing filter core depending on variations in the method parameters.
Dynamic Model of Electrical Discharge Machining and Algorithm of Extreme Control Through Acoustic Signal
Authors: Grigoriev Sergey , Kozochkin Mikhail , Porvatov Arthur , HtuM Thein , Zhavoronsky Pavel , Jiang Xiaohui , Pivkin Petr
Published: December 2019

Electrical discharge machining (EDM) is one of the most accurate methods for machining conductive materials and has a number of important applications. In the EDM process the occurrence of electric charges between cathode and anode is accompanied by vibroacoustic signals, which can be used to develop highly efficient control and diagnostics systems. Experimental studies and modelling of the dynamic system of the EDM process carried out in this study show that parameters of acoustic signals can be used to estimate the current productivity and risks of the tool-electrode breakage and to optimize the tool feed rate. The obtained results of allows using acoustic signals in the control system of the tool electrode feed rate to prevent its breakage, and also setting the interelectrode gap to maximum productivity.
Real-Time Simulation of Force Parameters for Diagnostics of Ceramic Tool Condition During Milling of High-Hardness Steel Parts
Authors: Volosova Marina A. , Gurin Vladimir D. , Seleznev Anton E. , Shvartsburg Leonid E. , Jenek Mariuch
Published: December 2019

Cutting ceramics is a high-performance tool material for high-speed machining of hard steels and alloys. Ceramic materials have high hardness and heat resistance in a wide range of temperatures, as well as chemical passivity in relation to most of the workpieces. However, the wider application of ceramic cutting tools is limited due to the low reliability - unpredictable fragile fracture of the cutting edge in different periods of operation. The study discusses mathematical simulations of force parameters in the milling of hardened steels using ceramic cutting tools. The simulation results were used to develop a system for the metalworking technological system state diagnostics. Mathematical software for calculations of the set of force parameters through computer simulations with taking into account the tool wear has been developed. The developed system allows calculating and graphically displaying a set of force parameters appearing during face milling of hardened steels in the real-time.
Simulation Modelling and Parametric Synthesis of Metal Working Machine Tools Mechatronic Systems of Surface Generation
Authors: Molodtsov Vladimir , Takács János , Párkányi Zoltán , Isaev Alexey
Published: December 2019

This paper presents the principles of the designing metal working machine tools mechatronic systems of surface generation which are optimal from the point of view of reproducing given part profiles. It is shown that the degree of their optimality is determined by the proximity of their characteristics to the frequency characteristics of an ideal low-pass filter. Mathematical methods for building compact mathematical models of the drive hardware, adequately describing the inertial and elastic characteristics of the elements of its structure, is described. These models are convenient for simulating control loops of the machine tools feed drives. A method for the parametric synthesis of a two-mass mathematical model of a subordinate control system for a feed drive with an elastic-dissipative coupling between equivalent lumped masses which simulate a moving unit and rotating elements of the drive mechanism is proposed. The synthesis problem is reduced to solving a system of nonlinear equations. Examples to demonstrate the proposed methods and models capabilities are given.
Entropy Economic Model of the Company
Authors: Ryzhkova Tatyana V.
Published: December 2019

The article discusses the entropy approach to the analysis of corporate financial system on the basis of the financial coefficients and market share price rates. The uncertainty of the corporate financial attractiveness is assessed using the entropy indicator of a random vector. Financial indicators such as Liquidity Financial Ratios, Operating Financial Ratios, Leverage Financial Ratios, Profitability Financial Ratios and Market Ratios serve here as vector components. Discrete entropy models of random vectors as well as differential entropy models for continuous probability distributions were used. It is shown that special probability distributions, approximately coinciding with the basic statistical ones for the first two moments, set the boundary of the maximum differential entropy. The entropy indicators were calculated based on the probability and entropy measures.
Analytical Processing of Applied Tasks Conceptual Models at Design of Information-Active Systems
Authors: Novoselova Olga , Ruzheynikov Anton , Gavrilov Andrey
Published: December 2019

The article describes the concept of the methodology of intellectual labor automation, a formal description of the conceptual model (CM) at the object level, and also a description of the analytical processing of CM. The conceptual model is the basis for the design of the system. The conceptual model of an applied task reflects the semantics (the system of knowledge) of the subject field in the form of static and dynamic structures and their linkage. The elements of the static structure are subject categories defined by classes: cycle, process, task, component, object, feature, value. The dynamic structure reflects the system of subject dependences which describes the process of performing a subject task. The main stage of conceptual model analytical processing is the restructuring of the dynamic component. The method and technique of descriptions restructuring of subject dependences system at the level of features are developed. The method allows to provide reduction of time and spatial expenses on performance of process of the decision of the applied task in the computing environment at early stages of information-active systems design
The elasto-plastic Point Method to estimate fatigue lifetime of notched metallic materials under variable amplitude multiaxial fatigue loading
Authors: Faruq Namiq Zuhair , Susmel Luca
Published: December 2019

The present paper deals with the formulation and implementation of a novel fatigue lifetime estimation technique suitable for designing notched components against multiaxial fatigue. This fatigue assessment procedure was devised by combining the Modified Manson-Coffin Curve Method and the Shear Strain-Maximum Variance Method with the elasto-plastic Point Method. The accuracy of the approach being proposed was checked against a large number of experimental results that were generated by testing notched cylindrical samples of medium-carbon steel En8. These tests were run under proportional/non-proportional constant/variable amplitude biaxial loading, with the effect of non-zero mean stresses and different frequencies between the axial and torsional stress/strain components being also investigated. The results from this validation exercise demonstrate that the novel multiaxial fatigue assessment methodology being proposed is highly accurate, with its systematic usage resulting in predictions falling within an error factor of 2. This remarkable level of accuracy is very promising especially in light of the fact that this approach can be applied by directly post-processing the results from elasto-plastic Finite Element (FE) models solved using commercial codes.
Aneurysmenbehandlung mithilfe der Methode des Endovascular aortic Repair
Authors: Pöttgens Nina
Published: December 2019

In diesem Artikel wird ausführlich die Bedeutung des Endovascular aortic Repair besprochen. Die einem Aneurysma zugrunde liegenden Gefäßproblematiken und Risikofaktoren werden erörtert. Anschließend wird die Indikationsstellung, die Patientenvorbereitung und die Methodik bzw. deren Komplikationen dargestellt.
Deep Learning in der SPECT und PET des Gehirns
Authors: Buchert Ralph , Krüger Julia , Gessert Nils , Lehnert Wencke , Apostolova Ivayla , Klutmann Susanne , Schlaefer Alexander
Published: December 2019

Deep Learning hat in den letzten Jahren in vielen Bereichen spektakuläre Erfolge erzielt, nicht zuletzt in der medizinischen Bildverarbeitung. Nach einer kurzen Einführung in die grundlegenden Ideen von Deep Learning sollen in diesem Übersichtsartikel einige ausgewählte Anwendungen in der SPECT und PET des Gehirns vorgestellt werden.
Die Würde des Menschen ist unantastbar –
Gesundheit/Gesundheitsversorgung ist ein Menschenrecht
Authors: Trabert Gerhard
Published: December 2019

Die Preisträgerrede behandelt die Rolle
Gesundheit/Gesundheitsversorgung als Menschenrecht in Deutschland im 21.
Jahrhundert und die daraus resultierenden Konsequenzen für
gegenwärtiges persönliches und politisches Handeln.
Identität und Integration – Salomon Neumann zur Syphilisfrage in Berlin
Authors: Gostomzyk Johannes G.
Published: December 2019

Die Schrift „Die Berliner Syphilis Frage. Ein Beitrag zur öffentlichen Gesundheitspflege Berlins“ unterstreicht in die Bedeutung von Salomon Neumann als einen Initiator der Sozialmedizin und Förderer der kommunalen Medizinalstatistik in der Mitte des 19 Jahrhunderts. Als Arzt des Berliner Gesundheitspflege-Vereins und Armenarzt gibt er einen für die Prävention und die Gesundheitsversorgung prospektiv orientierten sozialmedizinischen Bericht zu den Wechselwirkungen zwischen der Krankheit Syphilis und der Gesellschaft mit ihren ordnungsrechtlich-reglementierenden Maßregeln (Sittenpolizei, öffentliche Verwaltung) und den unzureichenden Strukturen der öffentlichen Gesundheitspflege sowie der defizitären ambulanten und stationären Gesundheitsversorgung armer Menschen in Berlin in der Mitte des 19. Jahrhunderts.
Impurity assisted hopping conduction and persistent photoconductivity in disordered carbon nanoparticle film
Authors: Singh Arvind , Nivedan Anand , Kumar Sandeep , Kumar Sunil
Published: December 2019

We report the temperature-dependent electrical transport and photoconductivity in carbon nanoparticle films. The electrical transport is dominated by thermally activated conduction at higher temperatures in the range of ∼350–285 K, whereas at lower temperatures <280 K, the conduction is mostly due to the hopping mechanism. A film of an n-type semiconductor with a carrier concentration of ∼1016 cm−3 is prepared by pulsed laser ablation in the scanning technique. The photoconductivity shows a persistent behavior that lasts for several hundreds of seconds on sub-bandgap laser excitations. A broad green luminescence spectrum suggests the presence of a large number of oxygenated-impurity states in the nanoparticles. An unusual behavior in the temperature-dependent photoluminescence is observed in which the photoluminescence intensity first increases up to ∼100 K with the increasing temperature followed by a continuous decrease at higher temperatures. The observed persistent nature of the photocurrent and anomalous temperature dependence in photoluminescence is attributed to the presence of a large number of trap states in the nanoparticles. Due to the ability to trap and retain charges within the disordered carbon nanoparticle films, it can be utilized in the memory applications.
Gradual resistive switching: Insights from inverse nonexponential decay and unified theoretical modeling
Authors: Wang Zhi-Hong , Cristiani G. , Habermeier H.-U. , Shen B.-G.
Published: December 2019

We report here a comprehensive study of the gradual resistive switching (RS) observed in La0.5Ca0.5MnO5−δ epitaxial films. We find that the inverse gradual RS as well as the relaxation can be well fitted by a biexponential function or alternatively by a stretched exponential function. We also unravel that the gradual RS kinetics can be further interpreted within the Landau-Khalatnikov theory of critical slowing down. This unified theoretical modeling properly incorporates the microstructural fluctuations owing to the presence of single isolated and clustered oxygen vacancies at the metal-oxide interface.
Effects of salinity on the onset of elastic turbulence in swirling flow and curvilinear microchannels
Authors: Yao Guice , Zhao Jin , Yang Haie , Haruna Maje Alhaji , Wen Dongsheng
Published: December 2019

Elastic turbulence, which is sensitive to geometry and polymer rheology, has shown great potential for improving the performance of mixing, heat transfer, and even oil recovery. Recent studies showed the importance of the rheological properties of polymer solutions on the onset of elastic turbulence. However, variations of rheological properties based on polymer sensitivities such as salinity and its corresponding effects on the elastic turbulence have not been revealed. This work investigated systematically the effects of salinity on the onset of elastic turbulence in both swirling flow and curvilinear microchannels. The variations of statistical properties, such as probability distribution functions (PDFs) and power spectral density of injected power (PSD), were analyzed for characterization. The onset conditions of elastic turbulence are postponed by high salinity, which is consistent with the mixing performance in a curvilinear microchannel. A salinity independent power-law exponent at a value of −4.3 is observed in a fully developed elastic regime for all polymer solutions. Particularly, the diffusion of fluorescein at a low flow rate in the microchannel is possible due to the existence of a steady secondary flow before the onset of elastic instability.
Direction reconfigurable nonreciprocal acousto-optic modulator on chip
Authors: Sohn Donggyu B. , Bahl Gaurav
Published: December 2019

Nonreciprocal components are essential in photonic systems for protecting light sources and for signal routing functions. Acousto-optic methods to produce nonreciprocal devices offer a foundry-compatible alternative to magneto-optic solutions and are especially important for photonic integration. In this paper, we experimentally demonstrate a dynamically reconfigurable nonreciprocal acousto-optic modulator at the telecom wavelength with a peak contrast of 8 dB and a 3 dB bandwidth of 1.1 GHz. The modulator can be arranged in a multitude of reciprocal and nonreciprocal configurations by means of an external RF input. The dynamic reconfigurability of the device is enabled by a new cross-finger interdigitated piezoelectric transducer that can change the directionality of the reciprocity-breaking acoustic excitation based on the phase of the RF input. The methodology we demonstrate here may enable new avenues for direction dependent signal processing and optical isolation.
Design of AlGaN-based quantum structures for low threshold UVC lasers
Authors: Guo Qiang , Kirste Ronny , Mita Seiji , Tweedie James , Reddy Pramod , Moody Baxter , Guan Yan , Washiyama Shun , Klump Andrew , Sitar Zlatko , Collazo Ramón
Published: December 2019

The influence of the polarization field on the emission properties of the AlGaN-based quantum structures grown on AlN substrates was investigated as a function of well width, barrier width, and barrier height. A thin AlGaN well and a thin AlN barrier design reduced the polarization field to ∼0.5 MV/cm, resulting in an ultralow laser threshold of 3 kW/cm2 in an optically pumped configuration. These experimental results were used to validate the simulation. In the next step, a structure with Al0.7Ga0.3N barriers was designed to support carrier injection with a minimal loss in optical performance. This structure showed a threshold of 7 kW/cm2 under optical pumping and an estimated threshold current of 8 kA/cm2 for the electric injection.
Generalized regimes for the formation of stratified regions during freezing of multi-component mixtures
Authors: Kumar Virkeshwar , Srivastava Atul , Karagadde Shyamprasad
Published: December 2019

Stratified double-diffusive layers (DDLs) in fluidic mixtures such as oceans, magma, and latte typically contain alternating low gradient mixing regions separated by high gradient interfaces. The prior knowledge is restricted to the formation of layers, but the existence of DDLs, under prolonged freezing conditions, as well as in multicomponent mixtures, is not yet understood well. In this work, a new observation depicting the existence of a life-cycle for a double-diffusive layer is revealed with the help of real-time observations of unidirectional freezing of multicomponent mixtures. The observations showed a systematic occurrence of the onset, formation, disappearance, and recurrence of the DDLs when freezing conditions prevailed for longer durations of time. The results also include first-ever observations of compositional stratification in a ternary mixture, which depends on the regimes and nature of buoyant convection. The ternary experiments also demonstrated the formation of DDLs much closer to the solidifying mush, which shed light on retaining the stratified layers in the frozen state. Furthermore, the hypothesized life-cycle of the DDL was mapped to the regimes of occurrence and the nonexistence of DDLs in the mixture phase diagrams of binary and ternary systems, with a threshold composition difference and the corresponding critical Rayleigh number. This distinction of the regimes on the phase diagram shows a striking correlation with a reduced ternary phase diagram of igneous rocks, thus providing a suitable basis for explaining the formation of layered rocks.
Analysis of local density potentials
Authors: DeLyser Michael R. , Noid W. G.
Published: December 2019

Low resolution coarse-grained (CG) models are widely adopted for investigating phenomena that cannot be effectively simulated with all-atom (AA) models. Since the development of the many-body dissipative particle dynamics method, CG models have increasingly supplemented conventional pair potentials with one-body potentials of the local density (LD) around each site. These LD potentials appear to significantly extend the transferability of CG models, while also enabling more accurate descriptions of thermodynamic properties, interfacial phenomena, and many-body correlations. In this work, we systematically examine the properties of LD potentials. We first derive and numerically demonstrate a nontrivial transformation of pair and LD potentials that leaves the total forces and equilibrium distribution invariant. Consequently, the pair and LD potentials determined via bottom-up methods are not unique. We then investigate the sensitivity of CG models for glycerol to the weighting function employed for defining the local density. We employ the multiscale coarse-graining (MS-CG) method to simultaneously parameterize both pair and LD potentials. When employing a short-ranged Lucy function that defines the local density from the first solvation shell, the MS-CG model accurately reproduces the pair structure, pressure-density equation of state, and liquid-vapor interfacial profile of the AA model. The accuracy of the model generally decreases as the range of the Lucy function increases further. The MS-CG model provides similar accuracy when a smoothed Heaviside function is employed to define the local density from the first solvation shell. However, the model performs less well when this function acts on either longer or shorter length scales.
Electrical conductivity, ion pairing, and ion self-diffusion in aqueous NaCl solutions at elevated temperatures and pressures
Authors: Yoon Tae Jun , Patel Lara A. , Vigil Matthew J. , Maerzke Katie A. , Findikoglu Alp T. , Currier Robert P.
Published: December 2019

We have performed classical molecular dynamics (MD) simulations of aqueous sodium chloride (NaCl) solutions from 298 to 674 K at 200 bars to understand the influence of ion pairing and ion self-diffusion on electrical conductivity in high-temperature/high-pressure salt solutions. Conductivity data obtained from the MD simulation highlight an apparent anomaly, namely, a conductivity maximum as temperature increases along an isobar, which has been also observed in experimental studies. By examining both velocity autocorrelation and cross-correlation terms of the Green-Kubo integral, we quantitatively demonstrate that the conductivity anomaly arises mainly from a competition between the single-ion self-diffusion and the contact ion pair formation. The velocity autocorrelation function in conjunction with structural analysis suggests that diffusive motion of ions is suppressed at high temperatures due to the persistence of an inner hydration shell. The contribution of velocity cross-correlation functions between oppositely charged ions becomes significant at the onset of the conductivity decrease. Structural analysis based on Voronoi tessellation and pair correlation functions indicates that the fraction of contact ion pairs increases as temperature increases. Spatial decomposition of the electrical conductivity also indicates that the formation of contact ion pairs significantly decreases the electrical conductivity compared to Nernst-Einstein conductivity, but the contribution of distant opposite charges cannot be ignored except at the highest temperature due to unscreened long-range interactions.
Electric field measurements under DC corona discharges in ambient air by electric field induced second harmonic generation
Authors: Cui Yingzhe , Zhuang Chijie , Zeng Rong
Published: December 2019

Electric field distribution is critically important for quantitative insights into the physics of nonequilibrium plasma like corona. To analyze the electric field as well as the ion flow (space charge) distribution under DC corona discharges, the ion flow model has been widely adopted; Kaptzov's assumption, which states that the steady state electric field at the conductor surface remains at the corona onset value, serves as a boundary condition. In this Letter, we investigate the electric field distribution under DC corona discharges between coaxial cylindrical electrodes in ambient air by electric field induced second harmonic generation with nanosecond pulse laser beams. The electric field distribution (with or without the corona discharge) is obtained. By comparing the measurements with the results predicted by the ion flow model for the negative corona discharge, it is found that the electric field at the conductor surface is proportional to the current density of the corona discharge with a negative constant of proportionality. Therefore, for negative corona discharges, Kaptzov's assumption is valid only when the discharge current approaches zero or is small.
Janus PtSSe and graphene heterostructure with tunable Schottky barrier
Authors: Cao Liemao , Ang Yee Sin , Wu Qingyun , Ang L. K.
Published: December 2019

Janus transition metal dichalcogenides with a built-in structural cross-plane asymmetry have recently emerged as a new class of two-dimensional materials with a large cross-plane dipole. By using the density functional theory calculation, we report the formation of different Schottky barriers for Janus PtSSe and graphene based van der Waals heterostructures, where the Schottky barrier height (SBH) and type of contact can be controlled by adjusting the interlayer distance, by applying an external electric field, and by having multiple layers of Janus PtSSe. It is found that the effects of tuning are more prominent for SPtSe/graphene as compared to SePtS/graphene. Besides, a transition from n-type Schottky contact to p-type Schottky contact and to Ohmic contact is also observed in the SPtSe/Gr heterostructure for different SPtSe stackings from 1 layer, to 2- and 3-layers, respectively. Our findings indicate that the SPtSe/graphene heterostructure is a suitable candidate for applications that require a tunable SBH.
Nanoscale mapping of carrier recombination in GaAs/AlGaAs core-multishell nanowires by cathodoluminescence imaging in a scanning transmission electron microscope
Authors: Müller Marcus , Bertram Frank , Veit Peter , Loitsch Bernhard , Winnerl Julia , Matich Sonja , Finley Jonathan J. , Koblmüller Gregor , Christen Jürgen
Published: December 2019

Mapping individual radiative recombination channels at the nanoscale in direct correlation with the underlying crystal structure and composition of III–V semiconductor nanostructures requires unprecedented highly spatially resolved spectroscopy methods. Here, we report on a direct one-by-one correlation between the complex radial structure and the distinct carrier recombination channels of single GaAs-AlGaAs core-multishell nanowire heterostructures using low temperature cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope. Based on an optimized focused ion beam fabrication of the optically active specimen, we directly visualize the radial luminescence evolution and identify four distinct emission lines, i.e., the near band edge and defect luminescence of the GaAs core (819 nm, 837 nm), the emission of the single embedded GaAs quantum well (QW, 785 nm), and the AlGaAs shell luminescence correlated with alloy fluctuations (650–674 nm). The detailed radial luminescence profiles are anticorrelated between QW luminescence and core emission, illustrating the radial carrier transport of the core-shell system. We inspected in detail the low-temperature capture of excess carriers in the quantum well and barriers.
Quarter-wave plate metasurfaces on electromagnetically thin polyimide substrates
Authors: Maiolo L. , Ferraro A. , Maita F. , Beccherelli R. , Kriezis E. E. , Yioultsis T. V. , Zografopoulos D. C.
Published: December 2019

We experimentally demonstrate that electromagnetically thin polyimide substrates can mitigate substrate-induced detrimental effects to the performance of metallic metasurfaces. A planar quarter-wave plate for the microwave K-band is fabricated on a polyimide substrate of deep subwavelength thickness by means of standard photolithography. By properly selecting the combination of the polyimide thickness and the aluminum layer thickness of the metasurface, conversion from linear to circular polarization is achieved at the design frequency. The proposed approach is generic, and it can be applied to the fabrication of mechanically robust, flexible metallic metasurfaces, which are primarily designed to work in a free-standing configuration.
Rational Construction of a 2D PbII Coordination Polymer as a Sensitive Turn-Off Fluorescent Switch for Fe3+, Cr2O72−, and NFT
Authors: Yi Li , Guo Feng
Published: December 2019

A PbII coordination polymer, [Pb(L)2]n (denoted as complex 1), was generated successfully by the assembly process of PbII and 5-fluoronicotinic acid (HL) under solvothermal synthesis. The obtained 1 was characterised by element analysis, powder and single-crystal X-ray diffraction, thermogravimetric analysis, and UV-vis and fluorescent spectroscopy. The resultant 1 has an outstanding application as a fluorescent sensor for Fe3+, Cr2O72−, and NFT with excellent selectivity and reusability.
Relationship of biological communities to habitat structure on the largest remnant flat oyster reef (Ostrea angasi) in Australia
Authors: Crawford C. , Edgar G. , Gillies C. L. , Heller-Wagner G.
Published: December 2019

Oyster reef restoration is a growing field in Australia, yet formal descriptions of associated biological communities for reefs created by native flat oysters (Ostrea angasi) do not currently exist. Native flat oysters once formed extensive and complex three-dimensional habitats in bays and estuaries across southern Australia until indiscriminate fishing, sedimentation and disease led to their near disappearance. To determine the diversity and abundance on naturally occurring oyster reefs, we sampled four sites on the last known naturally occurring oyster reef ecosystem, which resides in north-eastern Tasmania, and compared them to the surrounding soft sediment regions. Assemblages were related to environmental variables to determine whether consistent patterns were present. Oyster reef sites contained three times the faunal abundance of the surrounding soft sediment regions. Abundance among echinoderms, arthropods, molluscs and fish was much elevated, whereas annelids showed similar levels of abundance but differed in terms of species composition. These results show that oyster reefs do support abundant and diverse assemblages, emphasising the probable loss of community-level biodiversity associated with their historical decline around southern Australia.
Dimethyl sulfoxide and glycerol as cryoprotectant agents of stallion semen: effects on blastocyst rates following intracytoplasmic sperm injection of IVM equine oocytes
Authors: Cook Nancy L. , Masterson Keith R. , Battaglia David , Beck Rick , Metcalf Elizabeth S.
Published: December 2019

Numerous variables affect invitro blastocyst development following intracytoplasmic sperm injection (ICSI). The paternal factor is affected by initial semen quality, processing techniques and final selection of individual spermatozoon for injection. This study investigated whether there was an effect of sperm cryoprotectant agent (CPA) on equine invitro blastocyst production, and reviews recent developments examining how processing equine semen affects ICSI outcomes. Single ejaculates from five stallions were collected and processed in a freezing extender containing either 1M dimethyl sulfoxide (DMSO) or 3.5% glycerol. Immature equine oocytes were obtained from ovarian follicles of mares during diestrus by transvaginal aspiration (n=128). After invitro maturation, MII oocytes (n=90) were fertilised by ICSI with thawed stallion spermatozoa (n=45 in both the DMSO and glycerol groups). The embryo cleavage rate was greater in the DMSO than glycerol group (73.3% vs 46.7% respectively; P=0.0098), but the blastocyst development rate per fertilised oocyte was similar between the two groups (28.9% vs 15.6% respectively; P=0.128), as was the blastocyst production rate per cleaved embryo (39.4% vs 33.3% respectively; P=0.653). In this study, cryopreservation of equine spermatozoa in 1M DMSO was correlated with significantly higher cleavage rates in IVM oocytes fertilised by ICSI compared with spermatozoa cryopreserved using 3.5% glycerol. Although not statistically significant in this small number of stallions, increased blastocyst production and individual stallion variability was observed among CPA treatments. This warrants further critical examination of cryoprotectants used in equine sperm subpopulations used for ICSI in a larger number of stallions.
MiR-203a-3p targets PTEN to promote hepatocyte proliferation by regulating PI3K/Akt pathway in BRL-3A cells
Authors: Zhang Yingzi , Zheng Yunping , Zhu Guanmei
Published: December 2019

This study was designed to investigate the role of miR-203a-3p in hepatocyte proliferation. Data analysis showed that up-regulation of miR-203a-3p increased the cell viability and cell proliferation, and inhibited apoptosis. Further experiments demonstrated that PTEN was a target gene of miR-203a-3p, and miR-203a-3p targeted PTEN to regulate the above functions. Overexpression of PTEN partially reversed the inhibition of PTEN and the activation of p-Akt/Akt induced by miR-203a-3p mimic. Our study revealed that miR-203a-3p might activate PI3K/Akt signaling pathway by inhibiting PTEN expression, thereby promoting cell proliferation.