bluuebunny/crossref_metadata_2025 huggingface dataset:
Shedding light on the mitochondrial matrix through a functional membrane transporter
Authors: Blázquez-Moraleja Alberto , Sáenz-de-Santa María Ines , Chiara María D. , Álvarez-Fernández Delia , García-Moreno Inmaculada , Prieto-Montero Ruth , Martínez-Martínez Virginia , López Arbeloa Iñigo , Chiara Jose Luis
Published: December 2019

A BODIPY derivative of carnitine enters mitochondria regardless of their membrane potential and in an enantioselective way through a specific mitochondrial membrane transporter in living cells.
Visible-light-driven spirocyclization of epoxides via dual titanocene and photoredox catalysis
Authors: Lin Shuangjie , Chen Yuqing , Li Fusheng , Shi Caizhe , Shi Lei
Published: December 2019

We describe the synergistic utilization of titanocene/photoredox dual catalysis driven by visible light for radical opening/spirocyclization of easily accessible epoxyalkynes.
Single-atom catalysts for electrochemical clean energy conversion: recent progress and perspectives
Authors: Li Huining , Zhu Han , Zhuang Zechao , Lu Shuanglong , Duan Fang , Du Mingliang
Published: December 2019

We summarized here the recent progress and perspectives on single-atom catalysts for electrochemical clean energy conversion.
Preparation of hydrophobic epoxy–polydimethylsiloxane–graphene oxide nanocomposite coatings for antifouling application
Authors: Verma Shatakshi , Mohanty Smita , Nayak S. K.
Published: December 2019

Epoxy–polydimethylsiloxane–graphene oxide (EPG) nanocomposite coatings were synthesized by loading different wt% of graphene oxide nanosheets (GNs) into an epoxy–hydroxy-terminated-polydimethylsiloxane (EP–hPD) matrix throughin situpolymerization.
Free-standing 3D nitrogen–carbon anchored Cu nanorod arrays: in situ derivation from a metal–organic framework and strategy to stabilize lithium metal anodes
Authors: Yin Dongming , Huang Gang , Wang Shaohua , Yuan Dongxia , Wang Xuxu , Li Qian , Sun Qujiang , Xue Hongjin , Wang Limin , Ming Jun
Published: December 2019

A free-standing and integrated 3D nitrogen–carbon co-doped Cu nanorod arrays (3D NC/Cu) as a completely new current collector is in situ derived from the metal–organic framework (MOF) and can effectively address dendrite issues for lithium batteries.
W supported on g-CN manifests high activity and selectivity for N2electroreduction to NH3
Authors: Wang Shuhua , Wei Wei , Lv Xingshuai , Huang Baibiao , Dai Ying
Published: December 2019

W supported on novel 2D g-CN can be an efficient single atom catalyst (SAC) for electrocatalytic reduction of N2to NH3.
Film-depth-dependent crystallinity for light transmission and charge transport in semitransparent organic solar cells
Authors: Xiao Tong , Wang Jiayu , Yang Shuting , Zhu Yuanwei , Li Dongfan , Wang Zihao , Feng Shi , Bu Laju , Zhan Xiaowei , Lu Guanghao
Published: December 2019

We realized simultaneously optimized optical and electronic properties in semitransparent organic solar cells by tuning the film-depth-dependent crystallinity distribution.
Atomically dispersed asymmetric Cu–B pair on 2D carbon nitride synergistically boosts the conversion of CO into C2 products
Authors: He Tianwei , Reuter Karsten , Du Aijun
Published: December 2019

Asymmetric copper and boron dual-site synergy for boosting conversion of carbon monoxide into value-added C2 products under visible light.
Electrospun carbon nanofibers with MnS sulfiphilic sites as efficient polysulfide barriers for high-performance wide-temperature-range Li–S batteries
Authors: Wang Xin , Zhao Xiaosen , Ma Chenhui , Yang Zhenzhen , Chen Gang , Wang Lei , Yue Huijuan , Zhang Dong , Sun Zhenhua
Published: December 2019

Nanofibers with MnS sulfiphilic sites are introduced as flexible interlayers into Li–S batteries, reducing the shuttle effect and accelerating the reaction kinetics in wide work temperature range.
A chitosan modified asymmetric small-diameter vascular graft with anti-thrombotic and anti-bacterial functions for vascular tissue engineering
Authors: Wang Yilin , He Chao , Feng Yunbo , Yang Ye , Wei Zhiwei , Zhao Weifeng , Zhao Changsheng
Published: December 2019

Rapid endothelialization and prevention of restenosis are two vital challenges for the preparation of a small-diameter vascular graft (SDVG), while postoperative infection after implantation is often neglected.
Dual ultrasound-activatable nanodroplets for highly-penetrative and efficient ovarian cancer theranostics
Authors: Yang Chao , Zhang Yi , Luo Yuanli , Qiao Bin , Wang Xingyue , Zhang Liang , Chen Qiaoqi , Cao Yang , Wang Zhigang , Ran Haitao
Published: December 2019

Upon US irradiation, FA-H@NDs can be activated for ADV-augmented deep penetration of sonosensitizers and SDT-induced therapy.
Excimer formation effects and trap-assisted charge recombination loss channels in organic solar cells of perylene diimide dimer acceptors
Authors: Singh Ranbir , Kim Min , Lee Jae-Joon , Ye Tengling , Keivanidis Panagiotis E. , Cho Kilwon
Published: December 2019

Perylene diimide (PDI) multiadducts reveal the endemic characteristics of PDI-based OPVs: (a) excimer activation and (b) trap-limited charge recombination losses.
In situ investigation of perovskite solar cells’ efficiency and stability in a mimic stratospheric environment for high-altitude pseudo-satellites
Authors: Barbé Jérémy , Pockett Adam , Stoichkov Vasil , Hughes Declan , Lee Harrison Ka Hin , Carnie Matthew , Watson Trystan , Tsoi Wing C.
Published: December 2019

Perovskite solar cells with high power-per-weight have great potential to be used for aerospace applications such as satellites or high-altitude pseudo-satellites.
Bipolar resistive switching property of Si3N4−xthin films depending on N deficiency
Authors: Kwon Dae Eun , Kim Yumin , Kim Hae Jin , Kwon Young Jae , Woo Kyung Seok , Yoon Jung Ho , Hwang Cheol Seong
Published: December 2019

This study investigates a bipolar resistive switching property of a silicon nitride thin film deposited by plasma enhanced chemical vapor deposition using the SiH4and NH3as the Si- and N-sources, respectively.
Highly fluorescent free-standing films assembled from perylenediimide microcrystals for boosting aniline sensing
Authors: Lü Baozhong , Li Pengyu , Li Pengfei , Zhang Yantu , Müllen Klaus , Yin Meizhen
Published: December 2019

Molecular assembly has emerged as a key protocol for designing functional materials, although building in task-specific applications remains challenging.
Orange-red and white-emitting nonconventional luminescent polymers containing cyclic acid anhydride and lactam groups
Authors: Shang Cong , Zhao Yaxin , Long Jiayu , Ji Ying , Wang Huiliang
Published: December 2019

Nonconventional luminescent copolymers poly(itaconic anhydride-co-vinyl caprolactam) (PIVC) and poly(itaconic anhydride-co-vinyl pyrrolidone) (PIVP) emit strong orange-red and bright white emissions, respectively.
Stretch induced photoluminescence enhanced perovskite quantum dot polymer composites
Authors: Gong Yiqin , Shen Jianhua , Zhu Yihua , Yang Xiaoling , Zhang Ling , Li Chunzhong
Published: December 2019

Photoluminescence enhancement of stretched CsPbBr3 QDs@PDMS composites is caused by elimination of self-absorption due to the larger distance between QDs.
A structural topotactical transformation synthetic strategy for Y2O2S:Ln3+ micro/nanocrystals with multicolor emissions
Authors: Shao Baiqi , Yuan Senwen , Zhao Shuang , Dong Langping , Zhang Liang , You Hongpeng
Published: December 2019

A novel topotactic transformation synthetic strategy towards Y2O2S:Ln3+ with multicolor emissions was contrastively developed based on topotactic structural matching.
Oral Face-to-Face Versus Online Administration of the Public Opinion Survey of Human Attributes–Stuttering/Child
Authors: St. Louis Kenneth O. , Myers Lauren E. , Barnes Madison Flick , Saunders Meredith A. , Hall Becca M. , Weidner Mary E.
Published: December 2019

Background

The Public Opinion Survey of Human Attributes–Stuttering/Child (POSHA-S/Child;
Weidner & St. Louis, 2014
) is a standard instrument designed to measure the attitudes of children as young as 3 years of age toward stuttering. With preschool and early elementary school–aged children, the POSHA-S/Child is administered individually and face-to-face by an examiner. Older children who are satisfactory readers could be expected to respond to the instrument online, an increasingly popular mode of administering surveys.

Purpose

The purpose of this study was to compare administration of the POSHA-S/Child in face-to-face versus online administration.

Method

Children primarily from 1 elementary school and children from other areas in the region responded to the POSHA-S/Child in either a face-to-face individual setting or online. Three grade levels were included: 3rd grade, 4th grade, and 5th grade.

Results

POSHA-S/Child ratings for individual items, components, subscores, and the Overall Stuttering Scores from the 2 modes of administration were similar.

Conclusion

With satisfactory reading abilities, children aged 9 years and older can be administered the POSHA-S/Child online with similar results as face-to-face administration.
Internal null controllability of the generalized Hirota-Satsuma system
Authors: Carreño Nicolás , Cerpa Eduardo , Crépeau Emmanuelle
Published: December 2019

The generalized Hirota-Satsuma system consists of three coupled nonlinear Korteweg-de Vries (KdV) equations. By using two distributed controls it is proven in this paper that the local null controllability property holds when the system is posed on a bounded interval. First, the system is linearized around the origin obtaining two decoupled subsystems of third order dispersive equations. This linear system is controlled with two inputs, which is optimal. This is done with a duality approach and some appropriate Carleman estimates. Then, by means of an inverse function theorem, the local null controllability of the nonlinear system is proven.
Minimal time sliding mode control for evolution equations in Hilbert spaces
Authors: Marinoschi Gabriela
Published: December 2019

This work is concerned with the time optimal control problem for evolution equations in Hilbert spaces. The attention is focused on the maximum principle for the time optimal controllers having the dimension smaller that of the state system, in particular for minimal time sliding mode controllers, which is one of the novelties of this paper. We provide the characterization of the controllers by the optimality conditions determined for some general cases. The proofs rely on a set of hypotheses meant to cover a large class of applications. Examples of control problems governed by parabolic equations with potential and drift terms, porous media equation or reaction-diffusion systems with linear and nonlinear perturbations, describing real world processes, are presented at the end.
A deterministic game interpretation for fully nonlinear parabolic equations with dynamic boundary conditions
Authors: Hamamuki Nao , Liu Qing
Published: December 2019

This paper is devoted to deterministic discrete game-theoretic interpretations for fully nonlinear parabolic and elliptic equations with nonlinear dynamic boundary conditions. It is known that the classical Neumann boundary condition for general parabolic or elliptic equations can be generated by including reflections on the boundary to the interior optimal control or game interpretations. We study a dynamic version of such type of boundary problems, generalizing the discrete game-theoretic approach proposed by Kohn-Serfaty (2006, 2010) for Cauchy problems and later developed by Giga-Liu (2009) and Daniel (2013) for Neumann type boundary problems.
A Flow in a Thin Plastic Layer: Generalizations of the Prandtl’s Problem
Authors: Kadymov Vagid , Yanovskaya Elena
Published: December 2019

The analytical solutions of various generalizations of the classical L.Prandtl’s problem are of great interest in studying the problem of straightening plates using uniaxial stretching beyond the elastic limit. The straightening by stretching allows obtaining a high degree of flatness of thin wide strips and sheets of high-strength steels and special alloys, while the straightening by other methods does not provide satisfactory results. Based on Ilyushin’s theory of flow in a thin plastic layer, generalizations of the classical Prandtl’s problem on plastic strip compression were studied and their solutions were obtained. The planar problem of compression of a plastic strip between two parallel rough planes with accounting for the asymmetry of the conditions on the spreading ends has been solved and the upper estimate of the total compression force of the face-end areas of the plastically stretched strip has been obtained.
Mathematical Modeling of Impact of Possible Shock Dynamic Loads on the Modern Composite Materials
Authors: Sosenushkin Eugenе , Ivanova Oksana , Yanovskaya Elena , Vinogradova Yuliya
Published: December 2019

In this paper, we study the dynamic processes in materials reinforced with fibers, that can be represented as composite rods. There has been developed a mathematical model of wave propagation under the impact of a shock pulse in semi-infinite composite rods. It is believed that the considered composite rod consists of two layers formed by simpler rods of different isotropic materials with different mechanical properties. The cross sections of such rods are considered to be constant and identical. When such composite materials are impacted by dynamic loads, a significant part of the energy is dissipated due to the presence of friction forces between the contact surfaces of the rods. In this regard, we study the propagation of waves in an elastic fiber-rod, the layers of which interact according to Coulomb law of dry friction. The case of instantaneous excitation of rods by step pulses is investigated. The blow is applied to a rod made of a harder material. In the absence of slippage, the friction force gets a value not exceeding the absolute value of the limit. In the absence of slippage, the friction force takes a value not exceeding the absolute value of the limit. Let us consider the value of the friction force constant. Normal stresses and velocities satisfy the equations of motion and Hooke’s law. The problem statement results in the solution of inhomogeneous wave equations by the method of characteristics in different domains, which are the lines of discontinuities of the solution. Solutions are found in all constructed domains. On the basis of the analysis of the obtained solution, qualitative conclusions are made and curves are constructed according to the obtained ratios. From the found analytical solution of the problem it is possible to obtain ratios for stresses and strain rates in composite rods and composite materials.
Oscillatory Models for Biological Signal Processing and Pattern Recognition
Authors: Aksenova Tetiana , Ryzhkova Tatyana V.
Published: December 2019

Among biomedical signals, repetitive or quasi-periodic signals are particularly widespread. While the periodic component is still presented these signals are characterized by period variations (fundamental frequency, amplitude, etc.). The lack of synchronization or phase shifts results in variations in similar segments’ durations, nominally identical signals demonstrate a variation at peak retention times, etc. The inverse methods of oscillation theory were proposed recently as a tool to solve the problems of modelling of repetitive signals with phase shift. In the article, the inverse method of oscillation theory is considered as a tool to solve the problems of supervised and non-supervised classification, and filtering of repetitive signals with phase shift. Examples of application are presented.
Fermentative Metal – Containing Bio-Nano complexes, Quantum Chemical Models of Their Active Centers and Applications in Biotechnologies
Authors: Uvarova Ludmila , Romanova Ekaterina , Korobov Nikolai , Obukhova Elena , Krasikova Ekaterina
Published: December 2019

The general structure and the functional universal mechanism of the active centers of the fermentative metal-containing bio-nanocomplexes are discussed on the basis of the quantum-chemical approach using the conception “protein — machine”. The process, proceeding taking place in the active centers structure is the result of their interaction with the substrates. The active centers quantum-chemical models represent the electron distribution among the complex molecular orbitals (MO). The interaction of the central ions with the ligands is carried out by the donor-acceptor mechanism: the ions provide the connection of the vacant orbitals and connection of the vacant orbitals and the ligands — the unshared electron pair. One of the coordination bonds is functional, using for the interaction with substrates. From the quantum-chemical point of view the functional mechanism of the bio-nanocomplexes is universal. In the final, it is reduced to the functional electron accepting and the leaving in the molecular antibonding orbitals of the complex, inducing the active center transitions from one state to another. The electron-conformational transitions, the active centers changes at its functioning, the role of its protein surrounding may be explained on a basis of the conception “protein — machine”. The specific properties of the investigated bio-nanosystems are involved in the using of the internal valuable information, that is the process is a wave and occurs self-correlatively, and may be described by Kolmogorov-Petrovskii-Piskunov mathematical model. It is fair to say that the discussing bio-nanosystems are the natural intellectual tools, which may be used in the nanobiotechnologies and the spheres of its application are wide. It is necessary to conclude that the metal-containing bio-nanocomplexes are the self-organizing, self-congruent, nonlinear, open systems.
Effects of Heating Rate and Strain Rate on Phase Transformation in Micro-Grinding
Authors: Sun Gaoxiang , Ding Zishan
Published: December 2019

The phase transformation in the grinding process could have a significant impact on the processing performance of the products. Although grinding process can lead to high heating and strain rates, the current studies on the phase transformation typically consider temperature only that limits their accuracy. In this study, based on the phase transformation model, by conducting the micro-grinding experiment of maraging steel C250, the mechanism controlling impacts of heating and strain rates on phase transformation has been analyzed, and a new process optimization scheme to control phase transformation has been proposed. In this research was determinate main characteristic parameters of the phase transformation prediction model and influence of the heating rate parameters on the structure of the material. The main conclusions of this work are aimed increasing productivity, as well as criteria for optimizing the micro grinding process are defined.
Development of a Conceptual Model for Diagnosis of Priority Directions of Science and Technologies
Authors: Oleynik Andey , Gribkov Andrey , Chervyakov Leonid. , Dimitrov Lubomir
Published: December 2019

This article is dedicated to the development of a conceptual model for diagnosing priority areas of science and technology of the Russian Federation. The basic principles of the formation of the model and an enlarged list of controlled indicators allow to conduct a comprehensive assessment of the status and development of priority areas of science and technology. . The description of instrumental forecasting methods and a generalized algorithm for identifying the key factors/parameters, which impede the development of the object of analysis and cause critical bottlenecks, has been presented.
Analysis of the Quality Problem of Scientific School in the Higher Russian Technical Education by the Graduates and Professors of MSTU “STANKIN”
Authors: Mikhaylova Marianna V. , Revina Marina A.
Published: December 2019

Higher education reforms can give Russian higher technical schools significant advantages, but at the same time they hide serious dangers. As a result of these reforms, the modern higher technical school in Russia is facing many problems. Firstly, the quality problem: technical education in Russia has always been at a fairly high level, due to its integrity and fundamental nature, so the feasibility of reforms often raises questions. Secondly, the organizational problem: the natural process for higher education in the modernization of education and the consolidation of knowledge in itself is quite complicated. The combination of the modernization process and reform is causing considerable resistance and questions, since it seems insufficiently thought out. Thirdly, the problem of training a creative engineer for the society of the future does not find a solution, because the process of training a specialist is becoming more and more mechanistic. Previously, engineering students within five and a half years had the opportunity to join the scientific community, thanks to the presence of individual work and direct communication with scientists of different generations. Modern communication between professor and student is largely carried out through the electronic environment, so they are more fragmented and mosaic. The lack of real practice in enterprises leads to the fact that students do not receive a live request from production for their creativity. In such conditions, the training of creative technicians is very difficult. It is advisable to reform higher technical education in the light of these problems, so that in the final, Russian education will benefit from them, while maintaining its identity.
Method of Mapping for Semantic Static Constructions into Syntactic Constructions in the Design of Information-Active Systems
Authors: Volkova Galina D. , Novoselova Olga V. , Semyachkova Elena G. , Turbeyeva Tatiana B.
Published: December 2019

The design of information-active systems provides the formation of the model representation of automated tasks, which is invariant to the environment and means of software and hardware implementation. The syntactic (info-logical) model representation of applied problems will be adequate to initial requirements only if they provide meaningful unity. It is determined by the initial formation of a knowledge model or conceptual representation of applied tasks. The conjugation of semantic and syntactic static constructions is based on the regularity of mapping in the framework of the methodology of intellectual labor automation. The formal description of connections (mapping) of semantic (conceptual) and syntactic (info-logical) representations on the basis of the regularity of mapping allows limiting the set of possible relations and connections in verbal syntactical constructions for representation of subject tasks and providing completeness of the formalized (syntactic) representations at the expense of their semantic addition.
Akute peripartale Gefahrensituationen im Rettungsdienst
Authors: Strauss Alexander , Rath Werner , Gräsner Jan-Thorsten
Published: December 2019

Die meist akute Natur perinataler Notfallsituationen in Kombination mit einem
eingeschränkten diagnostischen Zugang, aber auch den begrenzten
therapeutischen Interventionsmöglichkeiten ist der prähospitalen
und z.T. aber auch der klinischen Geburtshilfe immanent. Das Erfordernis rascher
und zielgerichteter Maßnahmen kann sich dabei sowohl aus
mütterlicher, als auch aus kindlicher Indikation ergeben. Wie im
Rettungsdiensteinsatz bei Schwangeren allgemein üblich, kommt auf Basis
der Ersteinschätzung des Notarztes auch und gerade bei perinatalen
Notfällen dem Logistikmanagement (u.a. Transportzeit/-art,
Auswahl des Transportziels) wegwei-sende Bedeutung zu. Konkret sind diesem
Zusammenhang nicht-fachtypische geburtshilfliche Notfallsituationen von
spezifisch schwangerschaftsbedingten peripartalen Notfällen abzugrenzen.
Darunter sind im Wesentlichen der Formenkreis hypertensiver
Schwangerschaftserkrankungen, Blutungen, Thrombosen aber auch Embolien zu
verstehen. Sich seltene und wenig gut vorhersehbare Gefahrensituationen durch
standardisierte Entscheidungsprogramme erschließbar zu machen, fordert
zur Unterstützung der rettungsdienstlichen Ergebnisqualität
umfängliche, hier in Rahmen der Serie Geburtshilfliche Notfälle
vorgelegte, Informations-/Schulungskonzepte.
Treatment of the Neuroleptic Malignant Syndrome in International
Therapy Guidelines: A Comparative Analysis
Authors: Schönfeldt-Lecuona Carlos , Kuhlwilm Lilli , Cronemeyer Maximilian , Neu Peter , Connemann Bernhard J. , Gahr Maximilian , Sartorius Alexander , Mühlbauer Viktoria
Published: December 2019

Introduction The neuroleptic malignant syndrome (NMS) is a
potentially life-threatening condition associated to the use of
antipsychotics. Since it requires rapid and efficient medical care,
high-quality treatment guidelines should be available. In this article, we
analyzed and compared different international therapy guidelines for the
treatment of schizophrenia, in which NMS treatment recommendations might be
contained.

Methods We performed an Internet-based search for schizophrenia
guidelines via the website of the respective medical society. Guidelines in
English, French, Italian, and German from countries whose medical care meets
high standards were selected for further analysis and comparison of the NMS
treatment recommendations (if present), and their underlying evidence.

Results The NMS is mentioned in 12 of 14 guidelines. Only 9 report
concrete therapy recommendations
(benzodiazepines/dantrolene/bromocriptine/amantadine/intensive
care and/or electroconvulsive therapy (ECT)), however, with high
heterogeneity. Only 5 guidelines included all possible drug therapy options
and ECT, but with differing combination strategies, dosages, application
forms, and combinability of options. The level of evidence of the different
recommendations was estimated as low.

Discussion One-third of the selected guidelines do not report any NMS
therapy recommendations. Most guidelines mentioning the NMS do not provide
therapy recommendations that include all relevant treatment options. The
results show a very high heterogeneity, and the recommendations and
statements are of low-evidence levels. The lack of knowledge about the NMS
and its treatment may delay the onset of therapy, impair the quality of
treatment, and lead to a worse outcome or death.
Ethenesulfonyl Fluoride (ESF) and Its Derivatives in SuFEx Click Chemistry and More
Authors: Meng Yan-Ping , Wang Shi-Meng , Fang Wan-Yin , Xie Zhi-Zhong , Leng Jing , Alsulami Hamed , Qin Hua-Li
Published: December 2019

The sulfur(VI) fluoride exchange reaction (SuFEx), developed by Sharpless and co-workers in 2014, is a new category of click reaction that creates molecular connections with absolute reliability and unprecedented efficiency through a sulfur(VI) hub. Ethenesulfonyl fluoride (ESF), as one of the most important sulfur(VI) hubs, exhibits extraordinary reactivity in SuFEx click chemistry and organic synthesis. This review summarizes the chemical properties and applications of ESF in click chemistry, organic chemistry, materials science, medicinal chemistry and in many other fields related to organic synthesis.

1 Introduction

2 Chemical Transformations of ESF

3 Chemical Transformations of 2-Arylethenesulfonyl Fluorides

4 Novel SuFEx Reagents Derived from ESF

5 Applications of ESF Derivatives in Medicinal Chemistry

6 Applications of ESF Derivatives in Materials Science

7 Conclusion
Palladium-Catalyzed/Copper-Mediated Desulfurization and Aryl­­ation of Quinoline-2-(1H)-thione for Rapid Access to Quinoline Derivatives
Authors: Lu Hai-Long , Guo Fu-Hu , Wang Tong-Lin , Wang Xi-Cun , Quan Zheng-Jun
Published: December 2019

An efficient method for carbon–carbon bond formation is described. The process employs the palladium-catalyzed and copper-mediated cross-coupling of quinoline-2-(1H)-thiones with arylboronic acids or alkynes through C–S bond cleavage without an inert atmosphere. The method provides rapid and general access to a diverse range of 2-substituted quinolines in a single step from a wide range of quinoline-2-(1H)-thiones and arylboronic acids or alkynes.
Stability and control of power grids with diluted network topology
Authors: Tumash Liudmila , Olmi Simona , Schöll Eckehard
Published: December 2019

We consider sparse random networks of Kuramoto phase oscillators with inertia in order to mimic and investigate the dynamics emerging in high-voltage power grids. The corresponding natural frequencies are assumed to be bimodally Gaussian distributed, thus modeling the distribution of both power generators and consumers, which must be in balance. Our main focus is on the theoretical analysis of the linear stability of the frequency-synchronized state, which is necessary for the stable operation of power grids and the control of unstable synchronous states. We demonstrate by numerical simulations that unstable frequency-synchronized states can be stabilized by feedback control. Further, we extend our study to include stochastic temporal power fluctuations and discuss the interplay of topological disorder and Gaussian white noise for various model configurations and finally demonstrate that our control scheme also works well under the influence of noise. Results for synthetic Erdös–Renyi random networks with low average connectivity and with symmetric or asymmetric bimodal frequency distributions are compared with those obtained by considering a real power grid topology, namely, the grid of Italy.
Experimental methodology for measuring in-vacuum granular tribocharging
Authors: Carter D. , Hartzell C. M.
Published: December 2019

We have developed an experimental methodology for measuring the charge distribution in granular mixtures due solely to particle-to-particle triboelectric charge exchange. Our experiment isolates the charging process from common influencing factors such as particle-to-container contact and atmospheric effects, creating conditions ideal for studying charge exchange on airless, dusty extraterrestrial bodies like the Moon and Mars. Charged grains are observed using high-speed videography as they fall through a uniform electric field, and their charge and size are characterized from their trajectories. This no-contact measurement method does not influence the charge and allows for the characterization of the overall distribution of charge by grain size in an arbitrary mixture. Our preliminary results indicate that charging measured with this test stand agrees well with computational charging models.
A rapid technique for the determination of secondary electron emission yield from complex surfaces
Authors: Ottaviano Angelica , Banerjee Sankha , Raitses Yevgeny
Published: December 2019

Plasma-wall interaction in the presence of secondary electron emission (SEE) can lead to a degradation and reduction in the performance of plasma devices. Materials with complex surface architectures such as velvet, fuzz, and feathered surfaces have a lower SEE yield than the same materials with a flat surface and can, therefore, be useful for plasma applications. This reduction in the SEE is due to the trapping of secondary electrons in the microcavities formed by complex surfaces. In this paper, we present a rapid method for a simultaneous comparison of the SEE yield and surface properties of materials with different surface architectures. The method uses Scanning Electron Microscopy to simultaneously evaluate the surface morphologies and SEE yield properties for a microarchitectured surface. This technique was applied to carbon velvets, and results show agreement with recent theoretical models and with the direct determination of the SEE yield from measurements of the currents of the primary electrons impinging the surface and of the secondary electrons emitted from the surface.
Ge doped GaN and Al0.5Ga0.5N-based tunnel junctions on top of visible and UV light emitting diodes
Authors: Fan Arcara V. , Damilano B. , Feuillet G. , Vézian S. , Ayadi K. , Chenot S. , Duboz J.-Y.
Published: December 2019

The use of tunnel junctions (TJs) is a potential solution in blue light-emitting diodes (LEDs) to poor p-contacts, replacing it with another n-contact. TJs are even more advantageous for UV-emitting structures, which suffer from considerably low injection efficiency in high Al concentration UV LEDs. In this article, we report our work on Ge n-doped GaN and AlGaN TJs grown on top of blue and UV LEDs, respectively, by a hybrid growth method. We have achieved state-of-the-art mobility (67 cm2/V s) and resistivity (1.7 × 10−4 Ω cm) at a free electron concentration of 5.5 × 1020 cm−3 in Ge-doped GaN. With an emission wavelength of 436 nm, the GaN TJ slightly increased the optical power of the blue LED. The AlGaN TJs, on the other hand, improved the optical power of the UV LED (304 nm) by at least a factor of 3, suggesting the enhancement of the hole injection efficiency by the use of TJs in UV-emitting structures.
Nonlinear piezoresistance coefficients of semiconductors
Authors: Matsuda Kazunori , Uyama Hiroki , Tsutsui Kazuo
Published: December 2019

The inconsistency of symmetry relationships in nonlinear piezoresistance coefficients, which is a long-standing puzzle, is resolved by taking into account the complex relations between piezoresistance coefficients and piezoconductance coefficients. The procedure to obtain correct nonlinear piezoresistance coefficients in theory according to the coordinate transformations of tensors is suggested.
Influence of annealing temperature on physical properties of NaNbO3 thin films prepared by a water-based sol-gel process
Authors: Dong Huijuan , Luo Bingcheng , Jin Kexin
Published: December 2019

Sodium niobate (NaNbO3, NNO) has attracted considerable attention as a potential lead-free candidate for high-density energy-storage capacitors. An economical, environment-friendly, and low-temperature-synthesized route of NNO films is highly desirable for practical applications. In this study, a novel water-based solgel route was designed for the growth of NNO films, and the effects of annealing temperatures (400–600 °C) on microstructure and physical properties were investigated. By increasing the annealing temperature, the quality of (001)-preferred NNO films was improved, but a higher annealing temperature (e.g., 600 °C) induced the secondary phase, resulting in the degradation of electrical properties. As annealed at the optimum temperature of 500 °C, the highly (001)-preferred NNO film possessed advantageous characteristics including the largest difference between maximum polarization and remanent polarization (e.g., 26 μC/cm2 at 300 kV/cm), the maximum dielectric constant, and the minimum dielectric loss (e.g., 241.68 and 0.06 at 10 kHz). These results demonstrate a promising option toward solution-processed Nb-containing perovskite oxides through water-based sol-gel routes for energy-relevant applications.
Design of flexible piezoelectric gyroscope for structural health monitoring
Authors: Cao Yunqi , Sepúlveda Nelson
Published: December 2019

This Letter reports a piezoelectric bending sensor configuration based on a complementary design of four identical flexible piezoelectric sensors using both theoretical analysis and experimental demonstration. The active material used here for sensing is a flexible ferroelectret polymer, which possesses a cellular internal structure with distributed trapped charges. The transverse piezoelectric effect is observed by changing the permanent macroscaled dipole moments upon bending. It has been found that the voltage output for the sensor is linearly related to the bending curvature. Angular displacement is determined by monitoring the output of four orthogonal devices on a rod. Different types of surface stress can also be determined by measuring output polarities from an antiparallel electrical connection. The proposed sensor configuration in this work is capable of providing a nondestructive evaluation of structural health by measuring a 2D bending vector.
The source of volume beam-plasma formations based on a high-current non-self-sustained glow discharge with a large hollow cathode
Authors: Denisov V. V. , Akhmadeev Yu. H. , Koval N. N. , Kovalsky S. S. , Lopatin I. V. , Ostroverkhov E. V. , Pedin N. N. , Yakovlev V. V. , Schanin P. M.
Published: December 2019

The paper considers a plasma source based on a low-pressure (≈1 Pa) high-current (up to 450 A) non-self-sustained glow discharge with a hollow cathode of volume ≈0.2 m3. The research data are presented on the ignition stability of the discharge, on its main parameters, and on the radial and azimuthal plasma inhomogeneity varying with the pressure, discharge voltage and current, and anode-to-cathode area ratio at a plasma density of ≈1018 m−3 and an ionization degree of ≈1%. The beam plasma formations synthesized in such an electrode system of non-self-sustained glow discharge with a hollow cathode are interesting both from a scientific and technical point of view.
Dust-ion-acoustic rogue waves in presence of non-extensive non-thermal electrons
Authors: Rajib T. I. , Tamanna N. K. , Chowdhury N. A. , Mannan A. , Sultana S. , Mamun A. A.
Published: December 2019

Dust-ion-acoustic (DIA) rogue waves (DIARWs) are investigated in a three component dusty plasma system containing inertialess electrons featuring nonthermal nonextensive distribution as well as inertial warm ions and negatively charged dust grains. A nonlinear Schrödinger equation (NLSE), which governs the conditions of the modulational instability (MI) of DIA waves (DIAWs), is obtained by using the reductive perturbation method. It has been observed from the numerical analysis of NLSE that the plasma system supports both the modulationally stable domain, in which dispersive and nonlinear coefficients of the NLSE have the same signs, and the unstable domain, in which dispersive and nonlinear coefficients of the NLSE have opposite signs, and also supports the DIARWs only in the unstable domain. It is also observed that the basic features (viz., stability of the DIAWs, MI, growth rate, amplitude, width of the DIARWs, etc.) are significantly modified by the related plasma parameters (viz., dust charge state, number density of electron and ion, nonextensive parameter q, nonthermal parameter α, etc.). The present study is useful for understanding the mechanism of the formation of DIARWs in the laboratory and space environments where inertialess mixed distributed electrons can exist with inertial ions and dust grains.
Ring polymer molecular dynamics and active learning of moment tensor potential for gas-phase barrierless reactions: Application to S + H2
Authors: Novikov Ivan S. , Shapeev Alexander V. , Suleimanov Yury V.
Published: December 2019

Ring polymer molecular dynamics (RPMD) has proven to be an accurate approach for calculating thermal rate coefficients of various chemical reactions. For wider application of this methodology, efficient ways to generate the underlying full-dimensional potential energy surfaces (PESs) and the corresponding energy gradients are required. Recently, we have proposed a fully automated procedure based on combining the original RPMDrate code with active learning for PES on-the-fly using moment tensor potential and successfully applied it to two representative thermally activated chemical reactions [I. S. Novikov et al., Phys. Chem. Chem. Phys. 20, 29503–29512 (2018)]. In this work, using a prototype insertion chemical reaction S + H2, we show that this procedure works equally well for another class of chemical reactions. We find that the corresponding PES can be generated by fitting to less than 1500 automatically generated structures, while the RPMD rate coefficients show deviation from the reference values within the typical convergence error of the RPMDrate. We note that more structures are accumulated during the real-time propagation of the dynamic factor (the recrossing factor) as opposed to the previous study. We also observe that a relatively flat free energy profile along the reaction coordinate before entering the complex-formation well can cause issues with locating the maximum of the free energy surface for less converged PESs. However, the final RPMD rate coefficient is independent of the position of the dividing surface that makes it invulnerable to this problem, keeping the total number of necessary structures within a few thousand. Our work concludes that, in the future, the proposed methodology can be applied to realistic complex chemical reactions with various energy profiles.
Electron paramagnetic resonance signatures of Co2+ and Cu2+ in
β
-Ga2O3
Authors: Stehr Jan E. , Hofmann Detlev M. , Schörmann Jörg , Becker Martin , Chen Weimin M. , Buyanova Irina A.
Published: December 2019

Gallium oxide (β-Ga2O3) is a wide-bandgap compound semiconductor with a bandgap of ∼4.9 eV that is currently considered promising for a wide range of applications ranging from transparent conducting electrodes to UV optoelectronic devices and power electronics. However, all of these applications require a reliable and precise control of electrical and optical properties of the material, which can be largely affected by impurities, such as transition metals commonly present during the growth. In this work, we employ electron paramagnetic resonance (EPR) spectroscopy to obtain EPR signatures of the 3d-transition metals Co2+ and Cu2+ in β-Ga2O3 bulk crystals and powders that were unknown so far. Furthermore, we show that both Co2+ and Cu2+ preferentially reside on the octahedral gallium lattice site.
Manifestation of specific features of T-exciton migration in magnetic field effects on TT-annihilation in molecular crystals: Analysis of low-field resonances
Authors: Shushin A. I.
Published: December 2019

The manifestation of specific features of T-exciton migration in the shape of low field resonances (LFRs) in the magnetic field effects on the TT-annihilation in molecular crystals is studied in detail. The LFRs are shown to be caused by avoided crossing of spin-levels of T-excitons in magnetic fields nearly parallel to the axis of the zero field splitting interaction tensor. Simple and accurate formulas for the shape of the LFR-line are derived within the hopping model of T-exciton migration. With these formulas, we demonstrate that the LFR-line shape is fairly sensitive to the anisotropy of T-exciton migration, in particular, in quasi-one-dimensional (quasi-1D) and quasi-two-dimensional (quasi-2D) limits of exciton migration. The analysis of the shape is shown to allow for obtaining the magnitude of the small rate of jumps out of 1D and 2D spaces of fast migration in the cases quasi-1D and quasi-2D migration, respectively. In addition, this analysis enables one to obtain the spin relaxation rate of T-excitons.
Fabrication of potassium sodium niobate nano-particle/polymer composites with piezoelectric stability and their application to unsteady wind energy harvesters
Authors: Wang Zhenjin , Narita Fumio
Published: December 2019

We investigated the effects of poling conditions on the piezoelectric performance of potassium sodium niobate [(K,Na)NbO3, KNN]/polymer composites, to obtain their unsteady energy harvesting potential. KNN nanoparticle/polymer composites were designed and fabricated and the poling condition test was performed. The composites were polarized using the corona poling method for various poling conditions and then the piezoelectric coefficient d33 was measured. It was found that piezoelectricity does not decrease over days. Scanning electron microscopic observations were conducted to study the distribution of the nanoparticles in the matrix. Meanwhile, the microstructure of the composites was studied by X-ray diffraction. Unsteady wind energy harvesting tests were accomplished to investigate the output voltage characteristics in the KNN nanoparticle/polymer composites in unsteady winds. The study represents an important step in developing flexible energy harvesters with stable performance.
Process-induced defects in Au-hyperdoped Si photodiodes
Authors: Lim S. Q. , Lew C. T.-K. , Chow P. K. , Warrender J. M. , Williams J. S. , Johnson B. C.
Published: December 2019

Hyperdoped Si formed by implantation followed by pulsed laser melting is a promising material for enhanced near-infrared photodetection. To realize the full potential of this material, it is crucial to understand the nature of defects arising from the fabrication process and how these may impact device operation. Here, we identify through deep level transient spectroscopy the presence of a range of defects in the substrate depletion layer that arise from interactions between high dose ion implantation and pulsed laser melting, and investigate their annealing behavior up to 650°C. In particular, the detection of a vacancy complex E1(0.35) with densities as high as 1014cm−3 indicates that optical transitions between this level and the valence band may compete with the Au donor center, and hence could potentially contribute to the photocurrent in hyperdoped photodiodes.
Viability of superoxide-containing radical pairs as magnetoreceptors
Authors: Player Thomas C. , Hore P. J.
Published: December 2019

The ability of night-migratory songbirds to sense the direction of the Earth’s magnetic field is increasingly attributed to a photochemical mechanism in which the magnetic field acts on transient radical pairs in cryptochrome flavoproteins located in the birds’ eyes. The magnetically sensitive species is commonly assumed to be [FAD•− TrpH•+], formed by sequential light-induced intraprotein electron transfers from a chain of tryptophan residues to the flavin adenine dinucleotide chromophore. However, some evidence points to superoxide, O2•−, as an alternative partner for the flavin radical. The absence of hyperfine interactions in O2•− could lead to a more sensitive magnetic compass, but only if the electron spin relaxation of the O2•− radical is much slower than normally expected for a small mobile radical with an orbitally degenerate electronic ground state. In this study we use spin dynamics simulations to model the sensitivity of a flavin-superoxide radical pair to the direction of a 50 μT magnetic field. By varying parameters that characterize the local environment and molecular dynamics of the radicals, we identify the highly restrictive conditions under which a O2•−-containing radical pair could form the basis of a geomagnetic compass sensor. We conclude that the involvement of superoxide in compass magnetoreception must remain highly speculative until further experimental evidence is forthcoming.
The use of flow type dependent strain reduction factor to improve fiber orientation predictions for an injection molded center-gated disk
Authors: Chen Hongyu , Wapperom Peter , Baird Donald G.
Published: December 2019

To predict fiber orientation for injection molded parts, it is important to use a slow-kinetics orientation model and pay careful attention to the role of flow kinematics on orientation evolution speed. A model incorporating the impact of flow type on the fiber reorientation rate was tested by comparing with experimental data measured in an injection molded center-gated disk for both short and long glass fiber thermoplastics. Unlike the existing orientation models using a constant factor, a variable strain reduction factor (SRF) is expressed as a function of an objective flow-type parameter reflecting local flow kinematics. The use of this model improved the fiber orientation predictions at locations where the constant SRF, obtained from simple shear flow, deviated significantly from that based on the local flow kinematics.