bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharmacological insights into Merremia vitifolia (Burm.f.) Hallier f. leaf for its antioxidant, thrombolytic, anti-arthritic and anti-nociceptive potential
Authors: Akter Sahida , Jahan Israt , Khatun Mst. Riniara , Khan Mohammad Forhad , Arshad Laiba , Jakaria Md. , Haque Md. Areeful
Published: December 2020

Merremia vitifolia (Burm.f.) Hallier f., an ethnomedicinally important plant, used in the tribal areas to treat various ailments including fever, headache, eye inflammation, rheumatism, dysentery, jaundice and urinary diseases. The present study explored the biological efficacy of the aqueous fraction of M. vitifolia leaves (AFMV) through in vitro and in vivo experimental models. The thrombolytic and anti-arthritic effects of AFMV were evaluated by using the clot lysis technique and inhibition of protein denaturation technique, respectively. The anti-nociceptive activity of AFMV was investigated in Swiss Albino mice by acetic acid-induced writhing test and formalin-induced paw licking test. The antioxidant activities of AFMV, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and total reducing power, were also tested. The qualitative phytochemical assays exhibited AFMV contains secondary metabolites such as alkaloid, carbohydrate, flavonoid, tannin, triterpenoids and phenols. In addition, AFMV showed strong antioxidant effects with the highest scavenging activity (IC50 146.61 µg/mL) and reducing power was increased with a dose-dependent manner. AFMV also revealed notable clot lysis effect and substantial anti-arthritic activity at higher doses (500 µg/mL) as compared with the control. The results demonstrated a promising reduction of the number of writhing and duration of paw licking in acetic acid-induced writhing test and formalin-induced paw licking test in a dose-dependent manner, respectively. In conclusion, AFMV provides the scientific basis of its folkloric usage, suggesting it as the vital source of dietary supplement.
Research in Speech Science and Voice Disorders: The Promise of Modern Genetic Approaches in Improving Clinical Diagnosis and Treatment
Authors: Kimball Emily E. , Sayce Lea
Published: December 2020

Much of the research in speech science and voice biology characterizes disorders through observations of functional behaviors, physiological measurements (e.g., videostroboscopy, subglottic pressure, noninvasive electroencephalography, acoustics, etc.), and outcome metrics. This body of research contributes to our understanding of disease presentation and informs clinical assessment and treatment paradigms. However, when existing treatments are not consistently effective in empirical testing, these techniques are limited in the information they can provide for revising clinical plans and improving patient outcomes. Investigation into gene mutations and protein and gene-level changes in speech science and voice disorders is starting to elucidate the pathophysiology underlying these conditions. In this article, we discuss the strengths and limitations of research relying on behavioral and functional assessment and treatment efficacy data in speech science and voice. We also provide a basic overview of modern genetic research approaches that may lend to greater mechanistic and etiological understanding of the disorders our patients face.
Quality of service optimisation of device‐to‐device communications underlaying cellular networks
Authors: Osman Radwa Ahmed , Peng Xiao‐Hong , Omar Mohamed A. , Gao Qiang
Published: December 2020

Device‐to‐device (D2D) communications play a significant role in increasing the capacity of cellular networks. D2D enables direct interaction between mobile users without traversing the base station (BS) and at the same time causes interference between D2D and cellular links which can affect the system performance. To ensure efficient and reliable D2D operations within a cellular network, the related quality of service (QoS) requirement needs to be met in the design of such a system involving both D2D and cellular users in a same network. In this study, we have investigated three different transmission schemes (cellular, D2D and cooperative D2D modes) by deriving the closed‐form expressions of key QoS performance such as system reliability, achievable data rate, and energy efficiency for these three transmission schemes. Based on this establishment, we have also examined the effects of using different numbers of parallel relay branches and different number of relays within each branch on the network performance to reveal how effectively the cooperative D2D can enhance QoS in comparison with other transmission methods. The proposed approach can be optimised through adaptively selecting appropriate transmission schemes and, as a result, good trade‐offs between system reliability and efficiency can also be achieved under various environmental conditions.
QoE‐centric interference‐aware Stackelberg game for cache delegation relay in wireless multimedia communications
Authors: He Shuan , Wang Wei
Published: December 2020

Relaying multimedia with decent Quality of Experience (QoE) is paramount for future wireless networks. In this paper, the problem of multimedia cache relay delegation with device‐to‐device (D2D) communication interference is studied. A solution with gametheoretic cached multimedia relay is proposed considering the mutual interference between the downlink relay and the succeeding uplink communications. The interference between D2D and uplink is modelled in the game competition. In the proposed solution, the base station (BS) and relay device (RD) are treated as two rational game players, where the BS acts as the leader, and RD acts as the follower. The utilities of BS, and RD are modelled using the expected QoE of the user equipment (UE). Analytical modeling shows that the system achieves the desirable state by acquiring the Stackelberg game equilibrium between the BS, and RD. The models show that the RD gets positive incentives for relaying, the UE experiences better QoE through D2D communication, and BS achieves higher payoff. Various cases are quantitatively analysed whether the Nash Equilibrium exists with numerical discussion. Various relay to uplink ratios, amount of relay traffic, transmission distances between relay and uplink, as well as various numbers of interference uplinks are also studied.
Energy cooperation in wireless relay networks
Authors: Liu Xiangli , Liu Dongni , He Zhiyu , Li Zan
Published: December 2020

This work deals with the problem of insufficient energy caused by the frequent use of relay nodes in wireless sensor networks. Here, energy cooperation relay selection algorithm is proposed in energy heterogeneous networks. It is assumed that the location of relay nodes obeys a homogeneous Poisson point process (PPP), and the relay nodes adopt an adaptive energy collection technology, which can harvest energy from the surrounding environment and decide whether to use or store it according to the current energy status of the battery. The relay nodes are divided into three kinds: the communication relay, the candidate relay and the ordinary relay. The candidate relay nodes are determined by K‐medoids clustering algorithms and the ordinary relay nodes transmit energy to them. Finally, the number of data packets sent by relay nodes and the expression of the energy status of the battery are derived correspond to the relay cooperation selection algorithm. The simulation results show that the energy cooperation relay selection scheme effectively extends lifetime of the network when the total network energy is relatively small.
Disturbance estimation based tracking control for periodic piecewise time‐varying delay systems
Authors: Sakthivel Rathinasamy , Harshavarthini Shanmugam , Tatar Nasser‐Eddine
Published: December 2020

This work is mainly focused on the design of uncertainty and disturbance estimator‐based tracking control scheme for a class of periodic piecewise time‐varying delay systems with uncertainties and disturbances. Precisely, the considered system consists of several subsystems, where the fixed dwell time and switching sequence are utilised to achieve the coordination between each subsystem. By constructing Lyapunov–Krasovskii functional with time‐varying periodic piecewise matrices and employing the matrix polynomial approach, an uncertainty and disturbance estimator‐based periodic tracking control design is developed such that the trajectories of the considered system are driven to track the reference model. Moreover, the lumped disturbances so called the summation of uncertainties and exogenous disturbances are estimated with the aid of strictly proper low‐pass filter. Finally, a numerical example is presented to verify the effectiveness and advantages of the developed theoretical results.
Disturbance attenuation and response time improvement of permanent magnet synchronous linear motor by using robust predictive resonant current control
Authors: Wang Zhen , Zhao Jiwen
Published: December 2020

This paper proposes a robust predictive resonant current control to improve the dynamic and anti‐disturbance performance of the permanent magnet synchronous linear motor (PMSLM). First, the disturbance caused by parameters variation is considered in modelling PMSLM. Based on this model, a robust predictive current control (RPCC) with mover current and disturbance estimation is derived, which is used to simultaneously overcome the time‐delay and estimate the parameters disturbance. Then, in order to further suppress periodic disturbance caused by voltage source inverter non‐linearity, an appropriate resonant controller is embedded in the RPCC. Finally, a precise test platform based on semi‐physical system AD5435 is established, and experimental results show the validity of the proposed approach.
Online detection of inter‐turn short‐circuit fault in dual‐redundancy permanent magnet synchronous motor
Authors: Yang Yukai , Chen Yiguang , Hao Weijie
Published: December 2020

An online detection method for the inter‐turn short‐circuit fault (ISCF) of a dual‐redundancy permanent magnet synchronous motor (DRPMSM) is proposed. First, the electromagnetic relationships in a DRPMSM without mutual inductances are analysed theoretically upon the occurrence of the ISCF. Then, a simulation model of the motor with ISCF is established, and the arithmetic mean for the ratio of the squared amplitude difference between two sets of space voltage vectors to squared frequency is used to identify the faulty winding by the difference between the back electromotive force and impedance of the dual winding. It is shown to be valid even with variations in the load, speed, contact resistance, and number of short‐circuit turns. The simulation and experimental results thus verify the effectiveness of the proposed method.
A hybrid prediction model for photovoltaic power generation based on information entropy
Authors: Pu Shiping , Li Zhiyong , Wan Hui , Chen Yougen
Published: December 2020

Photovoltaic power is affected by various random and coupled meteorological factors, and its changing trend implies the non‐linear effects of these factors. According to the quantitative analysis results, a statistical prediction model is proposed to accurately predict the power, which is of great significance to the safe and efficient use of solar energy. In this study, the authors first use grey relation analysis to select four main meteorological factors affecting photovoltaic power. Further, they combine grey relation analysis with information entropy and apply grey relation entropy to similar day analysis. On this basis, they take grey relation analysis to optimise extreme learning machine model to establish the grey relation analysis‐extreme learning machine model, while taking similar day analysis to optimise firefly algorithm to establish the similar day analysis‐firefly algorithm. By combining the two sub‐models with information entropy, a hybrid prediction model for photovoltaic power generation based on information entropy is proposed. The experimental results show that in various weather conditions, the values of mean absolute percentage error, root mean square error and standard deviation of error are 2.8425%, 2.5675 and 2.2642, respectively. Therefore, the proposed hybrid model has superior prediction performance.
Molecule diffusion behaviours of waterproof sealants into silicone rubber insulation for submarine cable joint based on molecular dynamics simulations
Authors: Zhang Zhenpeng , Wang Heyu , Li Zhonglei , Zhao Jiankang , Wang Shaohua , Pan Wenlin , Li Wenjie , Li Te , Du Boxue
Published: December 2020

The repair joints of high‐voltage cables play a significant role in the urgent cable maintenance, by recovering cable conductor, insulation, shielding layer and waterproof layer especially for submarine cables. However, the molecule diffusion and permeation processes from waterproof sealant into the cable joint insulation occur, leading to the insulation ageing and deterioration. In this article, the molecule diffusion behaviours of six typical molecules from the asphalt‐based and polyurethane‐based waterproof sealants into silicone rubber insulation are investigated. The results show that the order of diffusion coefficients is as follows, phenanthrene > fluoranthene > pyrene > benzo [k] fluoranthene > indeno [1,2,3‐cd] pyrene > polyurethane (PU). The relative molecular mass and binding energy are pivotal factors affecting the diffusion behaviour, while there is a linear relationship between the logarithm of the diffusion coefficient and the ratio of binding energy to relative molecular mass. Besides, the rising ambient temperature increases the fraction of free volume of silicone rubber and decreases the binding energy, thus resulting in a higher diffusion coefficient and an enhanced permeation process of the asphalt‐based sealant. In summary, the PU‐based waterproof sealant, with a much lower permeability than the asphalt‐based material, has a potential application in the waterproof layer for high‐voltage submarine cable repair joints.
Performance of silicone rubber composites using boron nitride to replace alumina tri‐hydrate
Authors: Chen Xin , Wang Jiaqi , Zhang Chong , Yang Wei , Lin Jun , Bian Xingming , He Shaojian
Published: December 2020

Boron nitride (BN) has attracted increasing attention as a filler using in insulating materials. In this work, by using an equal amount of BN to replace alumina tri‐hydrate (ATH), various SR/BN/ATH composites were prepared, and for comparison, vinyl tri‐methoxysilane (VTMS) was added to prepare SR/BN/ATH‐VTMS composites. With the increasing BN content, Shore A hardness, breakdown strength and thermal conductivity of the silicone rubber (SR) composites increased despite the tensile strength slightly reduced. By replacing all the ATH with BN, the SR composite showed a ∼47% increase in breakdown strength, reaching 33.8 kV mm−1. The lower dielectric constant and dielectric loss were found for the SR composites with higher BN content, while the decreased dielectric loss and increased dielectric constant were achieved by the introduction of VTMS. Owing to the improved filler‐rubber interfacial interactions by adding VTMS, with the same BN content, all the SR/BN/ATH‐VTMS composites exhibited better property than the SR/BN/ATH composites. The best thermal conductivity of the SR composite reached 0.448 Wm−1 K−1, ∼156% higher than that of the ATH filled SR composite.
Le coton en Afrique de l’Ouest et du Centre : de la révolution agricole à la transition agro-écologique
Authors: Soumaré Mamy , Havard Michel , Bachelier Bruno
Published: December 2020

Depuis les années 1970, le coton a été un moteur dans la transformation des systèmes de production agricole et un élément structurant des économies locales dans les savanes d’Afrique de l’Ouest et du Centre (AOC). Cependant, la durabilité des systèmes de production à base de coton est souvent mise en débat à cause de leurs effets sur les sols et des impacts négatifs de la lutte chimique sur l’environnement et la santé humaine. Au moyen de réformes drastiques, le secteur coton en AOC a surmonté les crises, montrant sa capacité de résilience. Aujourd’hui, ce secteur est confronté à des défis importants sur lesquels la recherche doit se mobiliser : (i) économiques (volatilité des prix, revenus des producteurs, bien-être des communautés), (ii) sociaux (inclusion des couches vulnérables, rôle des femmes et des jeunes, etc.) et (iii) environnementaux (santé humaine, impact des pesticides, dégradation des sols, etc.) et liés au changement climatique. Ce numéro thématique présente des résultats et perspectives de travaux de recherche pouvant contribuer à améliorer la durabilité des systèmes cotonniers en AOC, à ouvrir des pistes vers une transition agro-écologique et à faire face aux nouveaux défis.
Qualimetric model for assessing the impact of the level of development of corporate information systems on the quality of aerospace instrumentation
Authors: Ovodenko Anatoliy , Ivakin Yan , Frolova Elena , Smirnova Maria
Published: December 2020

In the context of the digital transformation of the economy, the effective development of corporate information systems of research and production holdings of aerospace instrumentation is becoming one of the decisive factors in ensuring the high quality of domestic avionics. This article is devoted to the analysis of the influence factor of digitalization and informatization processes in scienceintensive industries of modern aerospace instrumentation, as well as the definition of a qualimetric model for assessing its impact on the quality of domestic avionics products in the current economic and technological conditions. The influence of the level of development of corporate information systems of aerospace instrumentation enterprises on the quality of domestic avionics products is assessed in the article on the basis of the corresponding hierarchy of quality indicators. The proposed model of the influence of the level of development of corporate information systems on the quality of aerospace instrumentation products assumes the choice of the form of the integral criterion depending on the external requirements for the efficiency of the assessment, the sensitivity of the system of quality indicators.
Using models of energy consumption from influencing factors to assess the current state and energy efficiency forecasting
Authors: Moroz Deniz , Hruntovich Nadzeya , Kapanski Aliaksei , Shenets Yauhen , Malashanka Mikhail , Gracheva Elena
Published: December 2020

A complex of tasks that can be solved using mathematical models of the dependence of consumed energy resources on influencing factors are considered in the article. The main type of model for industrial consumers with a simple relationship between energy and technology, is the one-factor model “consumed energy resource-volume of output”. For industrial consumers with a complex relationship between energy and technology, the mathematical model of the dependence of energy resources on technology is determined by several factors. Methods for assessing the current state of energy efficiency, as well as predicting it for the future in the context of the introduction of energy saving measures and changes in the production program were proposed.
Determination the conductor sag according to the period of own harmonic oscillations
Authors: Yaroslavsky Danil , Nguyen Van Vu , Sadykov Marat , Goryachev Mikhail , Ivanov Dmitry , Andreev Nikolay
Published: December 2020

The article substantiates the relevance of the inspection of overhead power lines by determining the mechanical loads of the conductors. The conductor sways under the action of external loads and variable internal mechanical loads. The conductor behaves in span like a pendulum. A model of the harmonic oscillations of the conductor in flight is derived to assess the mechanical loads of the conductor overhead power lines. This mathematical model is based on mathematical models of a flexible thread and a model of a physical pendulum. A conductor is a physical pendulum, where the conductor acts as the body, and in the role of the fixed axis of rotation, a straight line passing through the suspension points of the conductor. The article briefly describes an algorithm for calculating the conductor sag for the case when the conductor suspension points are at the same height. The results obtained using the developed model for calculating the sag of the conductor by its period are compared with the available experimental data. Experimental equipment is described. The error of the method is estimated.
Distribution of the components of the building mixture in the presence of secondary raw materials during rotary mixing
Authors: Kapranova Anna , Bahaeva Daria , Stenko Dmitry , Vatagin Alexander , Lebedev Anton , Lichak Dmitry
Published: December 2020

The purpose of this study is a stochastic description of the distribution of solid dispersed components, including those from secondary raw materials, according to the characteristic angle of scattering ϴij when receiving a construction mixture at the first stage of operation of the rotary apparatus. Two stages of the formation of rarefied flows are assumed: when scattering particles of components by elastic blades of a rotating drum and when interacting with the baffle surface. Modeling method this is energy method of Klimontovich Yu.L. The analysis of the efficiency of the first stage (rotary mixing) is carried out based on the obtained distribution functions of the number of particles of bulk components over the scattering angle, taking into account their physical and mechanical properties and a variety of design and operating parameters of the apparatus. The bulk of the particles of the mixed components are scattered at the initial angles of rotation of the mixing drum, when the deformation of the elastic blades is most significant. This is accompanied by the characteristic first bursts of the obtained distribution curves (ϴij< 0.1 rad) for the number of particles of the tested bulk materials at the given ranges of parameters.
Regularities of the formation of structural fields of daily gas consumption of the regional gas supply system
Authors: Moroz Deniz , Hruntovich Nadzeya , Hruntovich Nikolay , Kapanski Aliaksei , Markaryants Larisa , Shakurova Zumeyra
Published: December 2020

Daily statistics on the volume of gas consumption and the average daily outdoor air temperature for a six-year period were adopted as an information basis for scientific research with the matter of studying the functioning and developing of the regional gas supply system. For the regional gas supply system, the type of structural fields “daily gas consumption – average daily outdoor air temperature” was determined and their constancy over time was proved. For structural fields, 4 temperature ranges are allocated and a system of characterizing indicators was proposed. The regularities of the formation of daily gas consumption from the average daily outdoor air temperature for the proposed temperature ranges were established, the sensitivity coefficient of the relative change in the daily gas consumption with a relative daily change in the outdoor air temperature was determined. Daily models of the gas consumption dependence on the outdoor air temperature was developed, smoothed by a moving average over 30 days for two temperature regions: 1 - the area of the connected state of the heating system, 2 - the area of the disconnected state of the heating system. The seasonal coefficient of gas consumption was assessed.
Analysis of the effectiveness of using state observers in the control system of the traveling mechanism of the bridge crane trolley
Authors: Meshcheryakov Viktor , Sinyukova Tatyana , Sinyukov Alexey , Vladimirov O.V.
Published: December 2020

This article discusses the frequency control systems of an asynchronous electric drive with various types of observers that are promising for the movement mechanism of the bridge crane trolley. As a result of the analysis of existing control systems for asynchronous motors, it was revealed that the most relevant for use at the object under consideration is a system with direct torque control. To improve the classical control system, it is proposed to introduce a state observer into it. Sensorless control systems, in comparison with other systems, make it possible to reduce the dimensions of both a separate mechanism and the device as a whole, and reduce its cost. The use of observers leads to an increase in the reliability of an object without complicating its design. For the functioning of systems of this type, only data from the current and voltage sensors built into the frequency converter are used.
Dalmatiner mit Tetraparese
Authors: Wirtz Carina
Published: December 2020

Für Fibi gibt es nichts Schöneres als mit ihrem Herrchen und ihrem Hundefreund eine große Runde durch den Wald zu gehen, doch dieses war eines Tages nicht mehr möglich. Die 11-jährige Dalmalatinerdame wurde mit einer Tetraparese in der Tierärztlichen Klinik Ahlen vorstellig. Nach der bildgebenden Diagnostik stand fest, dass sie an einer idiopathischen Polyradiculoneuropathie erkrankt ist. Daraufhin wurde Fibi intensiv über mehrere Wochen physiotherapeutisch behandelt.
Insertion Reaction of 2-Halo-N-allylanilines with K2S Involving Trisulfur Radical Anion: Synthesis of Benzothiazole Derivatives under Transition-Metal-Free Conditions
Authors: Zhao Yan-Wei , Wang Shun-Yi , Liu Xin-Yu , Jiang Tian , Rao Weidong
Published: December 2020

A synthesis of benzothiazole derivatives through the reaction of 2-halo-N-allylanilines with K2S in DMF is developed. The trisulfur radical anion S3·–, which is generated in situ from K2S in DMF, initiates the reaction without transition-metal catalysis or other additives. In addition, two C–S bonds are formed and heteroaromatization of benzothiazole is triggered by radical cyclization and H-shift.
Argumentum ad Ignorantiam: Smartphone-Connected Listening Devices
Authors: Maidment David W. , Amlani Amyn M.
Published: December 2020

In this article, we review the current literature assessing the application and benefits of connected hearing technologies, as well as their potential to improve accessibility to and affordability of hearing healthcare. Over the past decade, there has been a proliferation of hearing devices that connect wirelessly to smartphone technologies via Bluetooth. These devices include (1) smartphone-connected hearing aids that must be obtained from a licensed audiologist or hearing aid dispenser; (2) direct-to-consumer devices, such as personal sound amplification products; and (3) smartphone-based hearing aid applications (or apps). Common to all these connected devices is that they permit the user to self-adjust and customize their device programs via an accompanying smartphone app. There has been a growing body of literature assessing connected hearing devices in adults living with hearing loss. Overall, the evidence to date supports the notion that all connected hearing devices can improve accessibility to and affordability of amplification. It is unclear, however, whether connected technologies are a clinically effective alternative to traditional hearing aids. Even so, the impact of connectivity is especially pertinent given the sudden disruption caused by the recent global COVID-19 pandemic, whereby connected technologies enable patients to receive treatment through mobile-based, tele-audiology platforms.
Behavioral Validation of the Smartphone for Remote Microphone Technology
Authors: Tittle Stephanie , Thibodeau Linda M. , Panahi Issa , Tokgoz Serkan , Shankar Nikhil , Bhat Gautam Shreedhar , Patel Kashyap
Published: December 2020

As part of a National Institutes of Health–National Institute on Deafness and Other communication Disorders (NIH-NIDCD)–supported project to develop open-source research and smartphone-based apps for enhancing speech recognition in noise, an app called Smartphone Hearing Aid Research Project Version 2 (SHARP-2) was tested with persons with normal and impaired hearing when using three sets of hearing aids (HAs) with wireless connectivity to an iPhone. Participants were asked to type sentences presented from a speaker in front of them while hearing noise from behind in two conditions, HA alone and HA + SHARP-2 app running on the iPhone. The signal was presented at a constant level of 65 dBA and the signal-to-noise ratio varied from −10 to +10, so that the task was difficult when listening through the bilateral HAs alone. This was important to allow for improvement to be measured when the HAs were connected to the SHARP-2 app on the smartphone. Benefit was achieved for most listeners with all three manufacturer HAs with the greatest improvements recorded for persons with normal (33.56%) and impaired hearing (22.21%) when using the SHARP-2 app with one manufacturer's made-for-all phones HAs. These results support the continued development of smartphone-based apps as an economical solution for enhancing speech recognition in noise for both persons with normal and impaired hearing.
Remote Learning for Children with Auditory Access Needs: What We Have Learned during COVID-19
Authors: Johnson Cheryl DeConde
Published: December 2020

COVID-19 has challenged most everyone in every facet of life. In the beginning of the pandemic shutdown, schools had to make decisions quickly often with limited planning. For students who were deaf or hard of hearing, communication access during instruction was the urgent focus of teachers of the deaf/hard of hearing and educational audiologists. The move from the classroom to home resulted in both predictable and unpredictable challenges as well as some unexpected benefits. Based on numerous conversations with these professionals as well as parents, the challenges encountered with online learning and solutions that were implemented to support students are reported.
Single-photon emission from two-dimensional hexagonal boron nitride annealed in a carbon-rich environment
Authors: Lyu Chao , Zhu Yaozheng , Gu Pingfan , Qiao Jiandong , Watanabe Kenji , Taniguchi Takashi , Ye Yu
Published: December 2020

For quantum photonic applications, such as quantum communication, optical quantum information processing, and metrology, solid-state sources of single-photon emitters are highly needed. Recently, single-photon emitters in two-dimensional (2D) van der Waals materials have attracted tremendous attention because of their atomic thickness, allowing for high photon extraction efficiency and easy integration into photonic circuits. In particular, a defect hosted by 2D hexagonal boron nitride (hBN) is expected to be a promising candidate for next-generation single-photon sources due to its chemical and thermal stability and high brightness at room temperature. Here, we report an effective method for generating single-photon emission in mechanically exfoliated hBN flakes by annealing in a carbon-rich environment. The one-step annealing in a mixed atmosphere (Ar:CH4:H2 = 15:5:1) greatly increases the single-photon emitter density in hBN. The resulting single-photon emission shows high stability and brightness. Our results provide an effective method for generating room-temperature single-photon emitters in 2D hBN.
First study of Hohlraum x-ray preheat asymmetry inside an ICF capsule
Authors: Dewald E. L. , Landen O. L. , Salmonson J. , Masse L. , Tabak M. , Smalyuk V. A. , Schiaffino S. , Heredia R. , Schneider M. , Nikroo A.
Published: December 2020

In indirect drive inertial confinement fusion (ICF), laser induced Hohlraum preheat radiation (so-called M-band, >1.8 keV) asymmetry will lead to asymmetric ablation front and ablator–fuel interface hydrodynamic instability growth in an imploding capsule. First experiments to infer the M-band asymmetries at the capsule were performed on the National Ignition Facility for high density carbon (HDC) ICF capsules in low density fill (0.3 mg/cc 4He) Au Hohlraums by time resolved imaging of 2.3 keV fluorescence emission of a smaller Mo sphere placed inside the capsule. Measured Mo emission is pole hot (P2 > 0) since M-band is generated mainly by the outer laser beams as their irradiance at the Hohlraum wall is 5× higher than for the inner beams. P2 has a greater negative than positive swing vs time [Δ(P2/P0)/Δt ∼ 0.2/ns], giving insight into laser heated Hohlraum dynamics. P4 asymmetry is small at the sphere due to efficient geometric smoothing of Hohlraum asymmetries at large Hohlraum-to-capsule ratios. The M-band P2 history is qualitatively reproduced by radiation hydrodynamic HYDRA simulations. The smaller P2 than that calculated earlier suggests either less outer beam spot motion and/or preheat emission. At late times, the observed P2 swing is larger and P4 is more negative than simulated, which could be due to inner beams being stopped more in the outer beams wall plasma bubble than simulated. Asymmetry at the HDC capsule inner surface (“ice–ablator interface”) is also inferred from the Mo emission asymmetry by an analytic viewfactor model, accounting for the Mo/HDC radius difference and HDC capsule opacity.
Place recognition with deep superpixel features for brain-inspired navigation
Authors: Zhao Jing , Tang Jun , Zhao Donghua , Cao Huiliang , Liu Xiaochen , Shen Chong , Wang Chenguang , Liu Jun
Published: December 2020

Navigation in primates is generally supported by cognitive maps. Such a map endows an animal with navigational planning capabilities. Numerous methods have been proposed to mimic these natural navigation capabilities in artificial systems. Based on self-navigation and learning strategies in animals, we propose in this work a place recognition strategy for brain-inspired navigation. First, a place recognition algorithm structure based on convolutional neural networks (CNNs) is introduced, which can be applied in the field of intelligent navigation. Second, sufficient images are captured at each landmark and then stored as a reference image library. Simple linear iterative clustering (SLIC) is used to segment each image into superpixels with multi-scale viewpoint-invariant landmarks. Third, highly representative appearance-independent features are extracted from these landmarks through CNNs. In addition, spatial pyramid pooling (SPP) layers are introduced to generate a fixed-length CNN representation, regardless of the image size. This representation boosts the quality of the extracted landmark features. The proposed SLIC-SPP-CNN place recognition algorithm is evaluated on one collected dataset and two public datasets with viewpoint and appearance variations.
Microstructural evolution in chemical solution deposited PbZrO3 thin films of varying thickness
Authors: Yu Ziyi , Cai Henghui , Fu Zhengqian , Zhang Linlin , Chen Xuefeng , Wang Genshui , Dong Xianlin , Xu Fangfang
Published: December 2020

Compared to the bulky ceramic counterparts, antiferroelectric (AFE) thin films exhibit higher energy-storage performance. It has been demonstrated that the performance of the AFE thin films is strongly affected by the thickness. However, possible changes in the phase structures and microstructures accompanied by varying thicknesses have been less known, which makes it hard to fully understand the physical insight of the thickness effect. Herein, we fabricate a series of PbZrO3 (PZ) thin films by chemical solution deposition whose thickness is approximately proportional to the number of deposition layers, i.e., one to four layers with each layer of about 60 nm in thickness. The detailed structural characterization has been performed by using x-ray diffraction, a scanning electron microscope, and a transmission electron microscope. The films are composed of nanorods oriented normal to the films in which each nanorod maintains single crystalline though segmented by the horizontal interfaces between each of the two neighboring layers, suggesting nearly perfect epitaxy during multilayer growth. The multidomain state is found in three-/four-layer PZ thin films while the one-/two-layer PZ films always present a monodomain state. Meanwhile, incommensurate phases with different modulation periods have been observed in the four-layer PZ films. By comparing the as-observed structural features with the measured electrical properties of different films, it seems that microstructural evolution with the film thickness should not be negligible in evaluating the structure–property relation of PZ-based thin films.
Effects of doping with Na, K, Rb, and formamidinium cations on (CH3NH3)0.99Rb0.01Pb0.99Cu0.01I3−x(Cl, Br)x perovskite photovoltaic cells
Authors: Ueoka Naoki , Oku Takeo , Suzuki Atsushi
Published: December 2020

The effects of doping with alkali metals and formamidinium cations on CH3NH3(Rb)Pb(Cu)I3(Cl,Br) perovskite photovoltaic cells were investigated. Lattice constants were slightly decreased and increased by K and Na doping, respectively. This indicated that Na atoms occupied interstitial sites in the perovskite crystal. The conversion efficiencies for most of the devices decreased after one year. However, the conversion efficiency for the CH3NH3(Na,Rb)Pb(Cu)I3(Cl,Br) photovoltaic cell was unchanged after one year. The Na-doped perovskite provided the smallest carrier trap density, which suggested that lattice defects were suppressed by Na doping. First principles calculations supported these experimental results.
Theoretical investigation of mixing and clustering thermodynamics of Ti1−xAlxB2 alloys with potential for age-hardening
Authors: Johansson Erik , Ektarawong Annop , Rosen Johanna , Alling Björn
Published: December 2020

Metastable ternary ceramic alloys with clustering tendencies are candidates for hard coating applications. In this work, mixing thermodynamics and structural parameters of ceramic Ti1−xAlxB2 alloys are investigated with theoretical first-principles based techniques. Lattice dynamics and temperature dependent phase stability are explored. The effect of lattice vibrations on the total free energy is investigated and found to not significantly affect phase stability at temperatures below 1200 K. The isostructural phase diagram is derived using both cluster expansion-based Monte Carlo simulations and a mean field approach. The phase diagram shows a miscibility gap that does not close at temperatures below the melting or decomposition temperatures of the constituent binaries TiB2 and AlB2. The lattice mismatch between phases in the system is small regardless of their composition even at elevated temperatures. These findings support the prospect of age hardening due to coherent isostructural decomposition, such as spinodal decomposition, in coatings of Ti1−xAlxB2 as diffusion is activated at elevated temperature.
Launcher of high-order Bessel vortex beam carrying orbital angular momentum by designing anisotropic holographic metasurface
Authors: Meng Xiangshuai , Chen Xiaoming , Yang Lin , Xue Wei , Zhang Anxue , Sha Wei E. I. , Cheng Qiang
Published: December 2020

In this paper, an ultra-low profile anisotropic holographic metasurface is proposed to generate a linearly polarized high-order Bessel vortex beam carrying orbital angular momentum with predesigned topological charge. Based on the leaky-wave theory and optical holographic principle, the anisotropic impedance pattern can be properly mapped by shaping the quasi-periodic metasurface with different meta-atom sizes. Compared with the prevalent spatial wave-modulated metasurface, this surface wave-modulated holographic metasurface effectively transforms a reference wave excited by a feeding source in a single point at the center of the antenna to a leaky high-order Bessel vortex beam without any extra air feeding, which enables a unique characteristic of error-free alignment between the air feeding and designed metasurface. The good agreement between the numerical simulation and the measured result demonstrates that the proposed approach can be employed to launch a linearly polarized high-order Bessel vortex beam with an arbitrary topological mode of interest.
Nonplanar ion-acoustic subsonic shock waves in dissipative electron-ion-pcd plasmas
Authors: Mamun A. A. , Sharmin B. E.
Published: December 2020

The dissipative electron-ion-pcd (positively charged dust) plasma, which is observed in both space and laboratory plasmas, is considered. The basic features of nonplanar cylindrical and spherical ion-acoustic subsonic shock waves in such a medium are investigated by deriving a modified Burgers equation using the reductive perturbation method. It is found that the stationary pcd species reduces the phase speed of the ion-acoustic waves and, consequently, supports the subsonic shock waves due to the kinematic viscosity (acting as a source of dissipation) of the ion species. It is observed that the cylindrical and spherical subsonic shock waves evolve with time very significantly and that the time evolution of the spherical shock structures is faster than that of the cylindrical ones. The implications of the results of this work to space and laboratory plasmas are discussed.
Recent advances in computational liquid-phase 77Se NMR
Authors: Krivdin Leonid B.
Published: December 2020

This review aims to highlight significant progress in the calculation of 77Se NMR chemical shifts and spin – spin coupling constants involving selenium substantiated with a vast amount of experimental data. The material is arranged in two basic sections: the first one dealing with the calculation of 77Se NMR chemical shifts and the second one dealing with the computation of spin – spin coupling constants involving 77Se nucleus, namely 77Se–1H, 77Se–13C and 77Se–77Se together with some more exotic types of couplings, 77Se – 15N, 77Se–19F, 77Se–29Si and 77Se–31P. A special attention is focused on the stereoelectronic effects involving selenium atom and their manifestation in the 77Se NMR spectra of organoselenium compounds studied with the aid of the modern calculation of 77Se NMR parametres in combination with experimental results.

The bibliography includes 114 references.
Bioanalytical applications of Mössbauer spectroscopy
Authors: Kamnev Alexander A. , Tugarova Anna V.
Published: December 2020

Data on the applications of Mössbauer spectroscopy in the transmission (mainly on57Fe nuclei) and emission (on57Co nuclei) variants for analytical studies at the molecular level of metal-containing components in a wide range of biological objects (from biocomplexes and biomacromolecules to supramolecular structures, cells, tissues and organisms) and of objects that are participants or products of biological processes, published in the last 15 years are discussed and systematized. The prospects of the technique in its biological applications, including the developing fields (emission variant, use of synchrotron radiation), are formulated.

The bibliography includes 248 references.
The β-encapsulation cage of rearrangement hotspot (Rhs) effectors is required for type VI secretion
Authors: Donato Sonya L. , Beck Christina M. , Garza-Sánchez Fernando , Jensen Steven J. , Ruhe Zachary C. , Cunningham David A. , Singleton Ian , Low David A. , Hayes Christopher S.
Published: December 2020

Significance

Many bacteria use the type VI secretion system (T6SS) to compete with other microorganisms in the environment. These systems eject spear-like projectiles that impale neighboring cells to deliver lethal toxins. Here, we report that antibacterial toxins encoded by rearrangement hotspot (
rhs
) genes are critical for assembly of the T6SS apparatus in
Enterobacter cloacae
. Rhs proteins fortify the trimeric cell-penetrating spike at the tip of the projectile, and their toxin-encapsulating cage structures are required for full secretion activity. These findings suggest that Rhs proteins mediate a quality control checkpoint to ensure that the spike is loaded with toxic cargo before the cell assembles the T6SS apparatus.
Biotin rescues mitochondrial dysfunction and neurotoxicity in a tauopathy model
Authors: Lohr Kelly M. , Frost Bess , Scherzer Clemens , Feany Mel B.
Published: December 2020

Significance

Pathological tau accumulation is implicated in a variety of neurodegenerative diseases, including frontotemporal dementia and Alzheimer’s disease. Based on a large-scale forward genetic screen in
Drosophila
, our study highlights a modifier of tau neurotoxicity, the enzyme biotinidase. Our results suggest that biotin status may represent a druggable metabolic pathway and a potential therapeutic approach to neuroprotection in human tauopathies.
Natural selection maintains species despite frequent hybridization in the desert shrubEncelia
Authors: DiVittorio Christopher T. , Singhal Sonal , Roddy Adam B. , Zapata Felipe , Ackerly David D. , Baldwin Bruce G. , Brodersen Craig R. , Búrquez Alberto , Fine Paul V. A. , Padilla Flores Mayra , Solis Elizabeth , Morales-Villavicencio Jaime , Morales-Arce David , Kyhos Donald W.
Published: December 2020

Significance

In Baja California, the deserts meet the coastal dunes in a narrow transition visible even from satellite images. We study two species pairs of desert shrubs (Encelia) that occur across this transition. Although these species can interbreed, they remain distinct. Using a combination of genetics, field experiments, three-dimensional imaging, and physiological measurements, we show that natural selection helps counteract homogenizing effects of gene exchange. Different habitats of these species create multiple mechanisms of selection—drought, salinity, herbivory, and burial, which together maintain these species in their native habitats and their hybrids in intermediate habitats. This study illustrates how environmental factors influence traits and fitness and how these in turn can maintain species, highlighting the importance of natural selection in speciation.
Transcriptional readout of neuronal activity via an engineered Ca
2+
-activated protease
Authors: Sanchez Mateo I. , Nguyen Quynh-Anh , Wang Wenjing , Soltesz Ivan , Ting Alice Y.
Published: December 2020

Significance

Molecular reporters that “remember” the activity history of a cell and give a corresponding signal that can be read out by imaging, sequencing, or other modalities are valuable tools for the study of neural networks. Here, we develop a reporter that drives stable expression of any transgene (such as a fluorescent protein) in response to cellular calcium activity during a user-defined time window. As calcium is a universal proxy for neural activity, our reporter provides a stable “snapshot” of neural activity which can be used for subsequent imaging, analysis, or manipulation of behavior-associated neural networks. A core feature of our reporter is an engineered calcium-activated protease, which cuts a protein sequence to reveal a transcription factor when cellular calcium levels rise.
Identification of novel targets of azithromycin activity against
Pseudomonas aeruginosa
grown in physiologically relevant media
Authors: Belanger Corrie R. , Lee Amy Huei-Yi , Pletzer Daniel , Dhillon Bhavjinder Kaur , Falsafi Reza , Hancock Robert E. W.
Published: December 2020

Significance

The host environment in which infection occurs plays a crucial role in the interaction between
Pseudomonas aeruginosa
and antibiotic treatments. To make up for the lack of new antibiotics, alternative approaches, such as combination therapy and discovery of novel activity of known antibiotics in the host environment, are vital for treatment of pathogens such as
P. aeruginosa.
This research demonstrates how in vitro conditions that closely mimic human infection more accurately reflect the antimicrobial activity of antibiotics. We have shown that azithromycin (AZM) has increased activity and synergy with synthetic peptides in physiologically relevant in vitro conditions and in vivo. Furthermore, this research also provides potential alternative mechanisms for the activity of AZM against
P. aeruginosa
.