bluuebunny/crossref_metadata_2025 huggingface dataset:
Subnanometer-scale imaging of nanobio-interfaces by frequency modulation atomic force microscopy
Authors: Fukuma Takeshi
Published: August 2020

Recently, there have been significant advancements in dynamic-mode atomic force microscopy (AFM) for biological applications. With frequency modulation AFM (FM-AFM), subnanometer-scale surface structures of biomolecules such as secondary structures of proteins, phosphate groups of DNAs, and lipid-ion complexes have been directly visualized. In addition, three-dimensional AFM (3D-AFM) has been developed by combining a high-resolution AFM technique with a 3D tip scanning method. This method enabled visualization of 3D distributions of water (i.e. hydration structures) with subnanometer-scale resolution on various biological molecules such as lipids, proteins, and DNAs. Furthermore, 3D-AFM also allows visualization of subnanometer-scale 3D distributions of flexible surface structures such as thermally fluctuating lipid headgroups. Such a direct local information at nano-bio interfaces can play a critical role in determining the atomic- or molecular-scale model to explain interfacial structures and functions. Here, we present an overview of these recent advancements in the dynamic-mode AFM techniques and their biological applications.
Plant transporters involved in combating boron toxicity: beyond 3D structures
Authors: Hrmova Maria , Gilliham Matthew , Tyerman Stephen D.
Published: August 2020

Membrane transporters control the movement and distribution of solutes, including the disposal or compartmentation of toxic substances that accumulate in plants under adverse environmental conditions. In this minireview, in the light of the approaching 100th anniversary of unveiling the significance of boron to plants (K. Warington, 1923; Ann. Bot.37, 629) we discuss the current state of the knowledge on boron transport systems that plants utilise to combat boron toxicity. These transport proteins include: (i) nodulin-26-like intrinsic protein-types of aquaporins, and (ii) anionic efflux (borate) solute carriers. We describe the recent progress made on the structure–function relationships of these transport proteins and point out that this progress is integral to quantitative considerations of the transporter's roles in tissue boron homeostasis. Newly acquired knowledge at the molecular level has informed on the transport mechanics and conformational states of boron transport systems that can explain their impact on cell biology and whole plant physiology. We expect that this information will form the basis for engineering transporters with optimised features to alleviate boron toxicity tolerance in plants exposed to suboptimal soil conditions for sustained food production.
Androgens and the masculinization programming window: human–rodent differences
Authors: Sharpe Richard M.
Published: August 2020

Human male reproductive disorders are common and may have a fetal origin — the testicular dysgenesis syndrome (TDS) hypothesis. In rats, experimentally induced TDS disorders result from disruption of fetal androgen production/action specifically in the masculinization programming window (MPW). MPW androgen action also programs longer anogenital distance (AGD) in male versus female rats; shorter male AGD is correlated with risk and severity of induced TDS disorders. AGD thus provides a lifelong, calibrated readout of MPW androgen exposure and predicts likelihood of reproductive dysfunction. Pregnant rat exposure to environmental chemicals, notably certain phthalates (e.g. diethyl hexl phthalate, DEHP; dibutyl phthalate, DBP), pesticides or paracetamol, can reduce fetal testis testosterone and AGD and induce TDS disorders, provided exposure includes the MPW. In humans, AGD is longer in males than females and the presumptive MPW is 8–14 weeks’ gestation. Some, but not all, epidemiological studies of maternal DEHP (or pesticides) exposure reported shorter AGD in sons, but this occurred at DEHP exposure levels several thousand-fold lower than are effective in rats. In fetal human testis culture/xenografts, DEHP/DBP do not reduce testosterone production, whereas therapeutic paracetamol exposure does. In humans, androgen production in the MPW is controlled differently (human chorionic gonadotrophin-driven) than in rats (paracrine controlled), and other organs (placenta, liver, adrenals) contribute to MPW androgens, essential for normal masculinization, via the ‘backdoor pathway’. Consequently, early placental dysfunction, which is affected by maternal lifestyle and diet, and maternal painkiller use, may be more important than environmental chemical exposures in the origin of TDS in humans.
Modelling and circuit realisation of a new no‐equilibrium chaotic system with hidden attractor and coexisting attractors
Authors: Lai Qiang , Wan Zhiqiang , Kamdem Kuate Paul Didier
Published: August 2020

This Letter reports a new no‐equilibrium chaotic system with hidden attractors and coexisting attractors. Bifurcation diagram shows that the proposed system generates chaos through period‐doubling bifurcation with the variation of system parameters, and the hidden chaotic and periodic attractors are visually given by phase portraits. The coexisting chaotic and periodic attractors from different initial conditions are observed in the system. The analogue circuit realisation and microcontroller‐based experimental implementation of the system are given to verify its physical existence.
Auto‐calibration of position offset for PMSM drives with uncertain parameters
Authors: Choi K. , Kim Y. , Kim S.‐K. , Kim K.‐S.
Published: August 2020

This Letter proposes a novel technique for automatic position offset calibration for permanent‐magnet synchronous machine (PMSM) drives. Contrary to existing methods, the proposed technique estimates and compensates for the position offset without using machine true parameters or signal injection, which is possible under the condition of zero‐current control at high enough speed where parameter‐dependent terms are eliminated. To achieve this condition using uncertain parameters, speed control with absolute value feedback and model‐free current control are devised. Additionally, under this condition, not only the misalignment of the position sensor but also the sensor delay can be considered as the position offset, which improves the accuracy of the calibration. The proposed approach will be verified by experimental results.
Security embedded dynamic resource allocation model for cloud data centre
Authors: Saxena D. , Singh A.K.
Published: August 2020

Cloud clients face high security risks while sharing physical resources with multiple users. A malicious cloud user exploits co‐residency and hypervisor vulnerabilities to steal and hamper sensitive information of victim virtual machine (VM). To address this alarming issue, this Letter proposes a secure resource allocation model by developing a threat detector based on the analysis of co‐located inter‐VM relations and a workload predictor in the background. The anomalous network traffic, response speed, bandwidth usage and illegal inter‐VM links are considered as security breaches indicator that assists in future threat detection beforehand and consequently guides the secure and resource efficient VM allocation. The comparison of proposed model with state‐of‐the‐art: FCFS, Random‐fit and NSGA‐II based resource allocation approaches indicate that it significantly reduce security threats by 77.38% and number of active servers up to 5.39% with improved resource utilisation up to 26.84% over Random‐fit.
Analytical model and optimisation design of surface‐mounted PM motors with Halbach arrays accounting for semi‐closed slots
Authors: Jing Libing , Gong Jun
Published: August 2020

In this study, an analytical model is proposed to calculate the magnetic field and electromagnetic torque (including cogging torque) in the surface‐mounted permanent‐magnet (SMPM) machines with Halbach arrays accounting for semi‐closed slots. The analytical model can be used to calculate both no load and load air gap magnetic field of SMPM. The permanent magnets (PMs) on the rotor are arranged Halbach array and each pole is divided into four segments. Additionally, in order to improve the performance of the SMPM, the analytical model is combined with genetic algorithm to optimise some parameters of the motor. The analytical results from the proposed model have been compared with those issued from finite‐element method. Finally, the 12‐slot/8‐pole motor is manufactured and the back‐electromotive force, iron loss and load characteristics are validated by experiments.
Effect of time‐harmonic current on the harmonic leakage inductance of fractional slot concentrated winding permanent magnet synchronous motor
Authors: Ming Li , Yuejun An , Zhiheng Zhang , Wenyu Deng , Guangyu Wang , Lijun Qi , Xiangling Kong , Delong Bi
Published: August 2020

Harmonic leakage inductance occupies a high proportion in the synchronous inductance of fractional slot concentrated winding permanent magnet synchronous motor (FSCW‐PMSM), and the synchronous inductance determines the operating performance of the motor. To calculate the harmonic leakage inductance and synchronous inductance of the FSCW‐PMSM fed by inverters, two‐dimensional finite element analysis and the analytical method are used to study the influence of time‐harmonic current on the harmonic leakage inductance of the three‐phase FSCW‐PMSM in this study, and the influence mechanism is revealed. The relationship between the time‐harmonic magnetic field and space harmonic magnetic field is obtained, and the harmonic leakage coefficient and the working harmonic coefficient with different slot‐pole combinations are investigated. The results show that the time‐harmonic current can reduce the harmonic leakage inductance and increase the magnetising inductance, but has little effect on the synchronous inductance under the unsaturated condition. A prototype was manufactured and tested to verify the accuracy of the analysis model. The research results provide beneficial help for the design of the three‐phase FSCW‐PMSM fed by inverters.
Die Nümbrechter Osteoporoseschule: ein stationäres und auch ambulantes Osteoporose-Schulungsprogramm
Authors: Peters Klaus M. , Bode Monika
Published: August 2020

Zur Behandlung der Osteoporose stehen seit vielen Jahren wirksame Medikamente zur Verfügung. Eine S3-Leitlinie zur Prophylaxe, Diagnostik und Therapie der Osteoporose der postmenopausalen Frauen und bei Männern erleichtert die Versorgung der Erkrankten. Die Compliance einer spezifischen medikamentösen Therapie der Osteoporose ist aber weiterhin nicht gut. Zur Verbesserung der Compliance wurden zahlreiche osteoporosespezifische Schulungen für Patienten eingeführt. Bei der Nümbrechter Osteoporoseschule, veröffentlicht 2008, handelt es sich um ein standardisiertes evaluiertes Schulungsprogramm, das multiprofessionell durchgeführt wird. Das Schulungsprogramm ist modular aufgebaut und besteht aus neun Modulen, die sowohl stationär als auch ambulant absolviert werden können. Zielgruppen der Schulung sind sowohl Osteoporosebetroffene, als auch Osteoporosegefährdete und an der Krankheit Interessierte. Nach Durchlaufen der Nümbrechter Osteoporoseschule führten 72 % der Patienten ihre Osteoporosemedikation nach 6 Monaten fort, nach 12 Monaten waren es noch 62 % (Tuncel et al. 2017). Nach durchgeführter Schulung erfolgt heutzutage eine standardisierte telefonische Befragung der Patienten nach 6 bzw. 24 Monaten. Danach führten 24 Monate nach erfolgtem Schulungsprogramm 89 % ihre erlernten Übungen regelmäßig weiter durch, 87 % gaben an, sich knochengesund zu ernähren, und 76 % führten ihre spezifische Osteoporosemedikation regelmäßig fort.
Ergogenic Effects of Bihemispheric Transcranial Direct Current Stimulation on Fitness: a Randomized Cross-over Trial
Authors: Codella Roberto , Alongi Rosario , Filipas Luca , Luzi Livio
Published: August 2020

Several types of routines and methods have been experimented to gain
neuromuscular advantages, in terms of exercise performance, in athletes and
fitness enthusiasts. The aim of the present study was to evaluate the impact
of biemispheric transcranial direct current stimulation on physical fitness
indicators of healthy, physically active, men. In a randomized,
single-blinded, crossover fashion, seventeen subjects (age:
30.9 ± 6.5 years, BMI: 24.8±3.1 kg/m2)
underwent either stimulation or sham, prior to: vertical jump, sit &
reach, and endurance running tests. Mixed repeated measures anova revealed a
large main effect of stimulation for any of the three physical fitness
measures. Stimulation determined increases of lower limb power
(+ 5%), sit & reach amplitude
(+ 9%) and endurance running capacity
(+ 12%) with respect to sham condition
(0.16<ηp2 < 0.41; p<0.05).
Ratings-of-perceived-exertion, recorded at the end of each test session, did
not change across all performances. However, in the stimulated-endurance
protocol, an average lower rate-of-perceived-exertion at iso-time was
inferred. A portable transcranial direct current stimulation headset could
be a valuable ergogenic resource for individuals seeking to improve physical
fitness in daily life or in athletic training.
Britanin Exhibits Potential Inhibitory Activity on Human Prostate Cancer Cell Lines Through PI3K/Akt/NF-κB Signaling Pathways
Authors: Zeng Qi , Zeng Yun , Zhan Yonghua , Nie Xu , Guo Yingying
Published: August 2020

Britanin, a natural pseudoguaiacane sesquiterpene lactone, has significant antioxidant and anti-inflammatory activity, but little is known about its tumor inhibitory activity and the underlying mechanism. Here, we demonstrated in vitro and in vivo that britanin inhibited the growth of human prostate cancer cell lines (PC-3, PC-3-LUC, and DU-145). Through in vitro study, the results showed that britanin significantly decreased cell proliferation, migration, and motility. The moderate toxicity of britanin was determined with an acute toxicity study. A luciferase-labeled animal tumor xenograft model and bioluminescence imaging were applied, combining with biological validation for assessing the tumor progression. In vivo results demonstrated that britanin inhibited the growth of PC-3-LUC. The interleukin-2 level in mice was upregulated by britanin, which indicated that britanin induced antitumor immune activation. In addition, britanin
downregulated the expression of nuclear factor (NF)-κB p105/p50, pp65, IκBα, pIκBα, phosphoinositide 3-kinase, pPI3k, Akt (protein kinase B, PKB), and pAkt proteins and upregulated expression of Bax. We discovered that britanin inhibits the growth of prostate cancer cells both in vitro and in vivo by regulating PI3K/Akt/NF-κB-related proteins and activating immunity. These findings shed light on the development of britanin as a promising agent for prostate cancer therapy.
High-performance Countercurrent Chromatography to Access Rhodiola rosea Influenza Virus Inhibiting Constituents
Authors: Langeder Julia , Grienke Ulrike , Döring Kristin , Jafari Mahtab , Ehrhardt Christina , Schmidtke Michaela , Rollinger Judith M.
Published: August 2020

In a cytopathic effect inhibition assay, a standardized Rhodiola rosea root and rhizome extract, also known as roseroot extract (SHR-5), exerted distinct anti-influenza A virus activity against HK/68 (H3N2) (IC50 of 2.8 µg/mL) without being cytotoxic. For fast and efficient isolation and identification of the extractʼs bioactive constituents, a high-performance countercurrent chromatographic separation method was developed. It resulted in a three-stage gradient elution program using a mobile phase solvent system composed of ethyl acetate/n-butanol/water (1 : 4 : 5 → 2 : 3 : 5 → 3 : 2 : 5) in the reversed-phase mode. The elaborated high-performance countercurrent chromatographic method allowed for fractionation of the complex roseroot extract in a single chromatographic step in a way that only one additional orthogonal isolation/purification step per fraction yielded 12 isolated constituents. They cover a broad polarity range and belong to
different structural classes, namely, the phenylethanoid tyrosol and its glucoside salidroside, the cinnamyl alcohol glycosides rosavin, rosarin, and rosin as well as gallic acid, the cyanogenic glucoside lotaustralin, the monoterpene glucosides rosiridin and kenposide A, and the flavonoids tricin, tricin-5-O-β-D-glucopyranoside, and rhodiosin. The most promising anti-influenza activities were determined for rhodiosin, tricin, and tricin-5-O-β-D-glucopyranoside with IC50 values of 7.9, 13, and 15 µM, respectively. The herein established high-performance countercurrent chromatographic protocol enables fast and scalable access to major as well as minor roseroot constituents. This is of particular relevance for extract standardization, quality control, and further in-depth pharmacological investigations of the metabolites of this popular traditional herbal remedy.
Basal Cisternostomy in Traumatic Brain Injury: An Idea whose Time has Come?
Authors: Goyal Nishant , Kumar Punit , Chaturvedi Jitender , Siddiqui Saquib Azad , Agrawal Deepak
Published: August 2020

Traumatic brain injury is associated with high morbidity and mortality. Since the introduction of decompressive craniectomy more than a century ago, no major surgical advancement has been introduced in this field in spite of neurosurgery having seen a sea change in general. Basal cisternostomy, introduced recently, is said to have great promise. In this regard, neurosurgeons need to understand the theory behind the recently introduced basal cisternostomy and whether it holds any merit or not.
Synthesis of Chiral N-Nitro-oxazolidin-2-ones and O-(β-Nitraminoalkyl) Carbamates in Liquefied 1,1,1,2-Tetrafluoroethane Medium
Authors: Zlotin Sergei G. , Arabadzhi Svetlana S. , Zharkov Mikhail N. , Kuchurov Ilya V.
Published: August 2020

A convenient synthesis of chiral N-nitro-oxazolidin-2-ones by nitration of α-amino acid derived 1,3-oxazolidin-2-ones containing one or two stereogenic centers with dinitrogen pentoxide in liquefied 1,1,1,2-tetrafluoroethane medium has been developed. The obtained N-nitroheterocycles were converted into enantiomerically pure O-(β-nitraminoalkyl) carbamates by treatment with ammonia or amines in the same solvent. The synthesized N-nitro compounds are slightly toxic in vitro to Human Embryonic Kidney 293 (HEK293) cells.
Reductive Cross-Coupling of Vinyl Electrophiles
Authors: Shu Xing-Zhong , Pang Xiaobo , Peng Xuejing
Published: August 2020

The synthesis of alkenes (olefins) is a central subject in the synthetic community. The transition-metal-catalyzed reductive cross-coupling of vinyl electrophiles has emerged as a promising tool to produce alkenes with improved flexibility, structural complexity, and functionality tolerance. In this review, we summarized the progress in this field with respect to cross-electrophile couplings and reductive Heck reactions using vinyl electrophiles.

1 Introduction

2 Cross-Electrophile Coupling of Vinyl Electrophiles

3 Reductive Heck Reaction of Vinyl Electrophiles

4 Summary and Outlook
Which Inotropic Drug, Dobutamine or Milrinone, Is Clinically More Effective in the Treatment of Postligation Cardiac Syndrome in Preterm Infants?
Authors: Korkmaz Levent , Ozdemir Ahmet , Pamukçu Özge , Güneş Tamer , Ozturk Mehmet Adnan
Published: August 2020

Objective This study aimed to detect which of the two main medicines suggested in the treatment of postligation cardiac syndrome (PLCS)—dobutamine or mirinone—possesses a more therapeutic effect. While doing this, clinicians are provided with a broader perspective on the treatment and follow-up of cases. The desire was to increase the treatability and monitor ability of the cases in question and hence their survivability.

Study Design A retrospective review of a cohort of infants with PLCS was conducted between March 2012 and December 2018. In the treatment of infants with PLCS, dobutamine (dobutamine study group-DSG) or milrinone (milrinone study group-MSG) was used. The respiration, cardiac, echocardiography, and perfusion parameters of the cases were assessed both before and after ligation. Based on the data obtained, both the effects of the medicines on PLCS and the difference between their therapeutic effects were studied. The accuracy of prognostication was assessed with receiver operating characteristic analyses.

Results PLCS was detected in 29 (34.1%) of 85 patent ductus arteriosus ligation cases in total. Of all the PLCS cases, 13 (44.8%) were treated with dobutamine and 16 (55.2%) with milrinone. It was observed that the effects of the medicines on the respiratory system and cardiovascular system manifested in the third and 6th hour, respectively. It was detected that both medicines had more effect on the systolic blood pressure (SBP) (area under the curve [AUC]: 0.997/0.996, p = 0.001/0.002) than on the diastolic blood pressure (AUC: 0.911/0.843, p = 0.032/0.046).

Conclusion Dobutamine and milrinone, two primary medicines that can be used in the treatment of cases with PLCS, possess similar therapeutic effects on this pathology. In addition, their postoperative therapeutic effects on the SBP are more in the foreground.
Acceptor dopant mediated electrical property modification in Bi0.5Na0.5TiO3-based piezoceramic
Authors: Taghaddos Elaheh , Charalambous Harry , Miller Steve , Safari Ahmad
Published: August 2020

The effect of Mn and Fe dopants on the electromechanical and electrochemical properties of 0.88[Bi0.5Na0.5]TiO3–0.08[Bi0.5K0.5]TiO3–0.04[Bi0.5Li0.5]TiO3 piezoceramic is investigated with particular emphasis on complex impedance in the temperature range from 450 to 600 °C. The impedance spectra have been simulated with equivalent circuits in order to extract bulk and grain boundary characteristics and to determine activation energies of conduction. Mn and Fe dopants considerably enhance the mechanical quality factor and decrease the dielectric loss compared to the undoped composition. Mn doping leads to dramatically higher resistivity in the bulk and a modest increase in the bulk activation energy. On the other hand, conductivity increases dramatically via Fe doping with a significant lowering of activation energy in the bulk and corresponding raising of the activation energy at grain boundaries in comparison to Mn-doped and undoped ceramic. The bulk conductivity of Fe-doped piezoceramic reaches as high as 0.01 S cm−1 at 600 °C.
Paired double parallelogram flexure mechanism clamped by corrugated beam for underconstraint elimination
Authors: Xi Shouzhi , Lai Lei-Jie
Published: August 2020

This Note presents a kind of paired double parallelogram (DP) flexure mechanism clamped by a sinusoidal corrugated beam to solve the problem of underconstraint of its secondary stages. The results show that the proposed mechanism effectively constrains the undesired motions of the secondary stages without changing the stiffness and the first-order natural frequency in the working direction. The second- and third-order natural frequencies of the mechanism are increased by 9.2% and 30.8%, respectively, which can effectively improve the dynamic characteristics of the DP mechanism.
A class of nonlinear parabolic equations with anisotropic nonstandard growth conditions
Authors: Liao Menglan
Published: August 2020

In this paper, a doubly nonlinear parabolic problem involving nonstandard growth conditions under homogeneous Dirichlet boundary conditions is studied. To be a little precise, first, some energy estimates and inequalities are exploited to obtain energy decay estimates of the solution. Then, it is proved that the rest field u(x, t) = 0 is asymptotically stable in terms of natural energy associated with the solution. Second, we give two new blow-up criteria that one of them is obtained to remove the exponent restriction by using an extended form of the concavity method and the other one is a blow-up result of weak solutions with arbitrarily high initial energy. Moreover, an extinction result is also showed by establishing a new auxiliary lemma. The present results of this paper complement and improve a recent paper investigated by Liu et al. [J. Math. Phys. 59, 121504 (2018)].
An integrated ultra-high vacuum apparatus for growth and in situ characterization of complex materials
Authors: Vinai G. , Motti F. , Petrov A. Yu. , Polewczyk V. , Bonanni V. , Edla R. , Gobaut B. , Fujii J. , Suran F. , Benedetti D. , Salvador F. , Fondacaro A. , Rossi G. , Panaccione G. , Davidson B. A. , Torelli P.
Published: August 2020

Here, we present an integrated ultra-high vacuum apparatus—named MBE-Cluster —dedicated to the growth and in situ structural, spectroscopic, and magnetic characterization of complex materials. Molecular Beam Epitaxy (MBE) growth of metal oxides, e.g., manganites, and deposition of the patterned metallic layers can be fabricated and in situ characterized by reflection high-energy electron diffraction, low-energy electron diffraction, Auger electron spectroscopy, x-ray photoemission spectroscopy, and azimuthal longitudinal magneto-optic Kerr effect. The temperature can be controlled in the range from 5 K to 580 K, with the possibility of application of magnetic fields H up to ±7 kOe and electric fields E for voltages up to ±500 V. The MBE-Cluster operates for in-house research as well as user facility in combination with the APE beamlines at Sincrotrone-Trieste and the high harmonic generator facility for time-resolved spectroscopy.
Local connectivity effects in learning and coordination dynamics in a two-layer network
Authors: Lugo Haydée , González-Avella Juan Carlos , San Miguel Maxi
Published: August 2020

Anticoordination and chimera states occur in a two-layer model of learning and coordination dynamics in fully connected networks. Learning occurs in the intra-layer networks, while a coordination game is played in the inter-layer network. In this paper, we study the robustness of these states against local effects introduced by the local connectivity of random networks. We identify threshold values for the mean degree of the networks such that below these values, local effects prevent the existence of anticoordination and chimera states found in the fully connected setting. Local effects in the intra-layer learning network are more important than in the inter-layer network in preventing the existence of anticoordination states. The local connectivity of the intra- and inter-layer networks is important to avoid the occurrence of chimera states, but the local effects are stronger in the inter-layer coordination network than in the intra-layer learning network. We also study the effect of local connectivity on the problem of equilibrium selection in the asymmetric coordination game, showing that local effects favor the selection of the Pareto-dominant equilibrium in situations in which the risk-dominant equilibrium is selected in the fully connected network. In this case, again, the important local effects are those associated with the coordination dynamics inter-layer network. Indeed, lower average degree of the network connectivity between layers reduces the probability of achieving the risk-dominant strategy, favoring the Pareto-dominant equilibrium.
Minority carrier lifetime and photoluminescence of mid-wave infrared InAsSbBi
Authors: Petluru Priyanka , Grant Perry C. , Muhowski Aaron J. , Obermeier Isabella M. , Milosavljevic Marko S. , Johnson Shane R. , Wasserman Daniel , Steenbergen Elizabeth H. , Webster Preston T.
Published: August 2020

Time-resolved photoluminescence measurements are reported for InAsSbBi alloys grown by molecular beam epitaxy with Bi mole fractions ranging from 0 to 0.8%, yielding minority carrier lifetimes on the order of hundreds of nanoseconds. The minority carrier lifetimes extracted from the time-resolved photoluminescence measurements are comparable to those of lattice-matched InAsSb grown at the same respective temperatures. Nomarski imaging shows that smooth, droplet-free surface morphologies are obtained in 1 μm thick InAsSbBi epilayers grown at temperatures between 360 and 380 °C. The alloy composition-dependent bandgap energies for the InAsSbBi samples are determined from temperature-dependent steady-state photoluminescence measurements and compared with the tetragonal distortion measured by x-ray diffraction to determine the Sb and Bi mole fractions of each sample. The minority carrier lifetime and the achievable extension of the InAsSb(Bi) cut-off wavelength are analyzed as functions of alloy composition and compared with the performance of InAsSb layers with similar growth parameters.
A contrast in the electronic structures of B ion implanted ZnO thin films grown on glass and silicon substrates by using x-ray absorption spectroscopy
Authors: Kumar Krishna , Wu Shi-Chen , Yu Yueh-Chung , Wei Da-Hua , Chiou Jau-Wern
Published: August 2020

Fabrication of suitable c-axis oriented boron doped zinc oxide (BZO) thin films is vital for many applications. The properties of films critically depend on film preparation methods and the type of substrate. Furthermore, ion implantation at a specific position or depth of a sample substantially affects the properties of films. In this study, a contrast between the electronic structure of ZnO thin films grown on glass and silicon (Si) substrates and then implanted with B ions at 40 keV with a concentration of 5 × 1013 ions/cm2 was investigated. The B ions were implanted using a 3 MV tandem accelerator. Secondary ion mass spectrometry, atomic force microscopy, and x-ray diffraction were used to study the distribution and depth of B ions, surface morphology, and the crystallinity of ZnO and BZO thin films. The preferential orientation, texture, surface roughness, and grain size of the ZnO thin films were affected by B ion implantation. O K-, Zn L3-, and K-edge x-ray absorption near-edge structure (XANES), and Zn K-edge extended x-ray absorption fine structure techniques were used to investigate the electronic structure of the BZO thin films and to determine the substrate influence. O K- and Zn L3-edge XANES spectra of the BZO/glass thin films revealed an enhanced electron transfer from Zn to O as compared to the BZO/Si thin film, implying that B implantation increased the negative effective charge on the O ions. Interestingly, in contrast to the definition of electronegativity, an increase (decrease) in the number of O 2p (Zn 3d/4sp) unoccupied states due to an enhanced O 2p–Zn 3d/4sp hybridization is observed in the BZO/Si thin film as compared to the BZO/glass thin film, suggesting an increase in the number of O 2p-dangling bonds. This would affect the conductivity and luminescent behavior of the ZnO/Si thin films after B doping, which will be useful in optoelectronic applications.
Evaluating the WFIP2 updates to the HRRR model using scanning Doppler lidar measurements in the complex terrain of the Columbia River Basin
Authors: Pichugina Yelena L. , Banta Robert M. , Alan Brewer W. , Bianco L. , Draxl C. , Kenyon J. , Lundquist J. K. , Olson J. B. , Turner D. D. , Wharton S. , Wilczak J. , Baidar S. , Berg L. K. , Fernando H. J. S. , McCarty B. J. , Rai R. , Roberts B. , Sharp J. , Shaw W. J. , Stoelinga M. T. , Worsnop R.
Published: August 2020

The wind-energy (WE) industry relies on numerical weather prediction (NWP) forecast models as foundational or base models for many purposes, including wind-resource assessment and wind-power forecasting. During the Second Wind Forecast Improvement Project (WFIP2) in the Columbia River Basin of Oregon and Washington, a significant effort was made to improve NWP forecasts through focused model development, to include experimental refinements to the High Resolution Rapid Refresh (HRRR) model physics and horizontal grid spacing. In this study, the performance of an experimental version of HRRR that includes these refinements is tested against a control version, which corresponds to that of the operational HRRR run by National Oceanic and Atmospheric Administration/National Centers for Environmental Protection at the outset of WFIP2. The effects of horizontal grid resolution were also tested by comparing wind forecasts from the HRRR (with 3-km grid spacing) with those from a finer-resolution HRRR nest with 750-m grid spacing. Model forecasts are validated against accurate wind-profile measurements by three scanning, pulsed Doppler lidars at sites separated by a total distance of 71 km. Model skill and improvements in model skill, attributable to physics refinements and improved horizontal grid resolution, varied by season, by site, and during periods of atmospheric phenomena relevant to WE. In general, model errors were the largest below 150 m above ground level (AGL). Experimental HRRR refinements tended to reduce the mean absolute error (MAE) and other error metrics for many conditions, but degradation in skill (increased MAE) was noted below 150 m AGL at the two lowest-elevation sites at night. Finer resolution was found to produce the most significant reductions in the error metrics.
Features of gas breakdown in narrow discharge gaps at high pressures
Authors: Knizhnik A. A. , Korobtsev S. V. , Medvedev D. D. , Potapkin B. V. , Belov N. K. , Grankina O. O.
Published: August 2020

Plasma treatment of porous polymeric materials is a critical technology for creating new polymer materials that can be used in various applications. Porous polymers can be used in new approaches for creation of safe and compact hydrogen storage systems that can dramatically change existing hydrogen energy utilization. There are other potential applications for the development of new types of biocompatible and biodegradable polymeric materials for general use and for creation of new types of implants and dressing materials in medicine. Clarification of breakdown conditions of narrow discharge gaps in the micrometer region and optimization of the treatment process for different gap dimensions is the goal of this paper. The article is devoted to the experimental study of the breakdown process in the discharge gap by pulsed barrier discharge at different pressures and gaps in the region of the minimum of the Paschen curve. New approximation of the Paschen curve with the variable γ as a function of Pd, which is in good correlation with experimental results, has been proposed. A new approach is proposed for treating the inner surface of dielectric material pores with a barrier discharge, optimizing the pressure inside the pores; treating pores of a micron size requires a pressure significantly higher than atmospheric. The first results were obtained, which demonstrated the possibility of modifying the thickness of the polymer material by treatment with the barrier discharge at the time of gas pressure relief in the discharge chamber.
Tunable cavity-enhanced terahertz frequency-domain optical Hall effect
Authors: Knight Sean , Schöche Stefan , Kühne Philipp , Hofmann Tino , Darakchieva Vanya , Schubert Mathias
Published: August 2020

Presented here is the development and demonstration of a tunable cavity-enhanced terahertz (THz) frequency-domain optical Hall effect (OHE) technique. The cavity consists of at least one fixed and one tunable Fabry–Pérot resonator. The approach is suitable for the enhancement of the optical signatures produced by the OHE in semi-transparent conductive layer structures with plane parallel interfaces. Tuning one of the cavity parameters, such as the external cavity thickness, permits shifting of the frequencies of the constructive interference and provides substantial enhancement of the optical signatures produced by the OHE. A cavity-tuning optical stage and gas flow cell are used as examples of instruments that exploit tuning an external cavity to enhance polarization changes in a reflected THz beam. Permanent magnets are used to provide the necessary external magnetic field. Conveniently, the highly reflective surface of a permanent magnet can be used to create the tunable external cavity. The signal enhancement allows the extraction of the free charge carrier properties of thin films and can eliminate the need for expensive superconducting magnets. Furthermore, the thickness of the external cavity establishes an additional independent measurement condition, similar to, for example, the magnetic field strength, THz frequency, and angle of incidence. A high electron mobility transistor (HEMT) structure and epitaxial graphene are studied as examples. The tunable cavity-enhancement effect provides a maximum increase of more than one order of magnitude in the change of certain polarization components for both the HEMT structure and epitaxial graphene at particular frequencies and external cavity sizes.
An averaging principle for fractional stochastic differential equations with Lévy noise
Authors: Xu Wenjing , Duan Jinqiao , Xu Wei
Published: August 2020

This paper is devoted to the study of an averaging principle for fractional stochastic differential equations in Rn with Lévy motion, using an integral transform method. We obtain a time-averaged effective equation under suitable assumptions. Furthermore, we show that the solutions of the averaged equation approach the solutions of the original equation. Our results provide a better understanding for effective approximation of fractional dynamical systems with non-Gaussian Lévy noise.
Self-ordering water molecules at TiO2 interfaces: Advances in structural classification
Authors: O’Carroll Dáire , English Niall J.
Published: August 2020

In the five-decade search for efficient photocatalysts to convert natural sunlight into hydrogen via photoelectrochemical (PEC) dissociation of water, the underlying physics and chemistry of PEC processes taking place at metal-oxide photocatalysts remains relatively poorly understood and is an active area of research by both theorists and experimentalists. This is surely the case for water structuring at metal-oxide surfaces, including their “self-ordering.” In this work, we apply classical molecular-dynamics techniques to investigate and classify the structure and ordering of water layers at two TiO2 surfaces—anatase ⟨101⟩ and rutile ⟨110⟩. We are interested in identifying and classifying layers using local order parameters to distinguish the layered-water superstructure from bulk-like water configurations as observed in liquid water and common ice polymorphs. In particular, we look for the formation of regions with reduced molecular mobility and assess whether they are “ice-like,” as has been proposed in recent interpretations in the literature, or, instead, how these interfacial-water structures might be otherwise described. We leverage quantitative and order-parameter analysis techniques to categorize the structural properties of layers of water molecules formed and compare them to both cubic and hexagonal polytypes of bulk ice I, as well as bulk liquid water. In doing so, we propose a general structural recognition/classification framework suitable for identifying and describing molecules at any condensed-state-water interface.
A generalized linear threshold model for an improved description of the spreading dynamics
Authors: Ran Yijun , Deng Xiaomin , Wang Xiaomeng , Jia Tao
Published: August 2020

Many spreading processes in our real-life can be considered as a complex contagion, and the linear threshold (LT) model is often applied as a very representative model for this mechanism. Despite its intensive usage, the LT model suffers several limitations in describing the time evolution of the spreading. First, the discrete-time step that captures the speed of the spreading is vaguely defined. Second, the synchronous updating rule makes the nodes infected in batches, which cannot take individual differences into account. Finally, the LT model is incompatible with existing models for the simple contagion. Here, we consider a generalized linear threshold (GLT) model for the continuous-time stochastic complex contagion process that can be efficiently implemented by the Gillespie algorithm. The time in this model has a clear mathematical definition, and the updating order is rigidly defined. We find that the traditional LT model systematically underestimates the spreading speed and the randomness in the spreading sequence order. We also show that the GLT model works seamlessly with the susceptible-infected or susceptible-infected-recovered model. One can easily combine them to model a hybrid spreading process in which simple contagion accumulates the critical mass for the complex contagion that leads to the global cascades. Overall, the GLT model we proposed can be a useful tool to study complex contagion, especially when studying the time evolution of the spreading.
High sensitivity face shear magneto-electric composite array for weak magnetic field sensing
Authors: Lu Yun , Cheng Zhenxiang , Chen Jianguo , Li Weihua , Zhang Shujun
Published: August 2020

A magnetic field sensor is designed and fabricated using a piezoelectric face shear mode Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT)/Metglas magneto-electric (ME) composite. An outstanding ME coupling coefficient up to 1600 V/(cm Oe) was experimentally achieved, being ∼50% higher than the value from the extensional PMN–PT/Metglas ME composite with the same volume. The detection limit was found to be 2 × 10−6 Oe for the DC magnetic field, while it was 2 × 10−8 Oe for the AC magnetic field. The sensitivity of the face shear mode PMN–PT/Metglas ME composite is about one order of magnitude higher than that of a 32 extensional mode PMN–PT/Metglas based ME composite in sensing a weak DC magnetic field. A sensing array was also designed based on the ME composite to image weak DC magnetic fields, demonstrating a great potential promising for sensing weak magnetic fields.
Charge-separated spectra of suprathermal highly charged bismuth ions in a dual laser-produced plasma soft x-ray source
Authors: Kawasaki Hiromu , Tamura Toshiki , Sunahara Atsushi , Nishikino Masaharu , Namba Shinichi , O’Sullivan Gerry , Higashiguchi Takeshi
Published: August 2020

We investigated the charge-separated spectra of highly charged suprathermal bismuth (Bi) ions from a dual laser-produced plasma soft x-ray source developed for soft x-ray microscopy. The charge distribution of these suprathermal ions emitted from a solid planar Bi target was measured by an electrostatic energy analyzer. The maximum ionic charge state was observed to be Z = 17 and to possess a maximum energy of about 200 keV. This evaluation provides important information essential for the development of debris mitigation schemes in a soft x-ray microscope.
Defects chemistry in high-efficiency and stable perovskite solar cells
Authors: Chen Yihua , Zhou Huanping
Published: August 2020

It is the defects that determine the physicochemical properties and photoelectrical properties of the corresponding semiconductors. Controlling defects is essential to realize high-efficiency and stable solar cells, particularly in those based on hybrid halide perovskite materials. Here, we review the defect chemistry in perovskite absorbers, most of which take effects at grain boundaries and surfaces. These defects impact kinetics and/or thermodynamics during the courses of charge recombination, ion migration, and degradation in the corresponding devices, which inevitably influences their efficiency and stability. The effective suppression of harmful defects in perovskite photovoltaics not only reduces non-radiative recombination centers to improve the efficiency, but also retards their degradation under aging stresses to dramatically improve their long-term operational stability. Finally, the future challenges with regard to the in-depth understanding of defects formation, migration, and their passivation are presented, which shed light on realizing high-efficiency and stable perovskite optoelectronics.
Cooperation delay induced chaos in an ecological system
Authors: Pal Saheb , Hossain Mainul , Panday Pijush , Pati N. C. , Pal Nikhil , Chattopadhyay Joydev
Published: August 2020

In the present paper, we investigate the impact of time delay during cooperative hunting in a predator–prey model. We consider that cooperative predators do not aggregate in a group instantly, but individuals use different stages and strategies such as tactile, visual, vocal cues, or a suitable combination of these to communicate with each other. We observe that delay in hunting cooperation has stabilizing as well as destabilizing effects in the system. Also, for an increase in the strength of the delay, the system dynamics switch multiple times and eventually become chaotic. We see that depending on the threshold of time delay, the system may restore its original state or may go far away from its original state and unable to recollect its memory. Furthermore, we explore the dynamics of the system in different bi-parameter spaces and observe that for a particular range of other parameter values, the system dynamics switch multiple times with an increase of delay in all the planes. Different kinds of multistability behaviors, the coexistence of multiple attractors, and interesting changes in the basins of attraction of the system are also observed. We infer that depending on the initial population size and the strength of cooperation delay, the populations can exhibit stable coexistence, oscillating coexistence, or extinction of the predator species.
Cherenkov-type three-dimensional breakdown behavior of the Bloch-point domain wall motion in the cylindrical nanowire
Authors: Ma Xiao-Ping , Zheng Jiangshan , Piao Hong-Guang , Kim Dong-Hyun , Fischer Peter
Published: August 2020

A three-dimensional breakdown behavior of the magnetic Bloch-point domain wall (BP-DW) propagation was investigated in a ferromagnetic nanowire with the variation of the external magnetic field by means of micromagnetic simulation. As magnetic field strength increases up to a threshold value, the BP-DW velocity approaches a critical phase velocity of the spontaneously emitting spin wave (SW), where a Cherenkov-type DW breakdown phenomenon is observed originating from an interaction between the spontaneously emitting SW and the BP-DW. It is found that the velocity of the BP-DW approaches a maximum value (∼2000 m/s) due to the intrinsic reversal time of a BP spin texture. This suggests that although cylindrical ferromagnetic nanowires might be free from the two-dimensional Walker breakdown phenomenon, there exists a Cherenkov-type three-dimensional breakdown behavior.
Investigation of relaxation phenomenon in lanthanum orthoferrite extracted through complex impedance and electric modulus spectroscopy
Authors: Manzoor Samiya , Husain Shahid , Somvanshi Anand , Fatema Mehroosh
Published: August 2020

Impedance and electric modulus spectroscopy is exploited over a broad frequency and temperature range to find the relaxation phenomenon in LaFeO3 (LFO), which otherwise was concealed by the dc conductivity in dielectric ɛ*(ω) representation. The impedance measurements and the ac resistivity determined from Z′(ω) indicate that LFO is an insulator at room temperature and divulges the negative temperature coefficient of resistance. At higher temperatures, capacitive behavior flips to inductive behavior. The ac resistivity is exploited to determine the activation energy using the Arrhenius model. The relaxation peaks appear in the imaginary parts of electric modulus [M*(ω)] and impedance [Z(ω)], which have been exploited to determine the activation energy. The single distorted semicircle in the Nyquist and complex plots of electric modulus is evidence of the contribution of grains in the conduction process. At higher temperatures, data corresponding to the grain interior transform from an arc to a line with an intercept on the Z′(ω) axis and is parallel to the imaginary axis Z″(ω). Relaxation times calculated from the imaginary parts of impedance and electric modulus fit well in accordance with the Arrhenius law. Electron hopping, hole hopping, and oxygen vacancies play an important role in the dielectric response of grains. The relaxation frequencies of Z″(ω) and M″(ω) follow the sequence of scaling of magnitude of relaxation frequencies, i.e., fz′′≤fM′′. The separation of relaxation peaks of M″(ω) and Z″(ω) are indicative of a localized conduction process. The Giuntini law is applied to determine the hopping energies of charge carriers.