bluuebunny/crossref_metadata_2025 huggingface dataset:
Simple and efficient visualization of aromaticity: bond currents calculated from NICS values
Authors: Paenurk Eno , Gershoni-Poranne Renana
Published: February 2022

Introducing NICS2BC, a new method that uses simple and inexpensive NICS calculations to generate information-rich and easily-interpreted bond-current graphs.
Water–oxidation mechanism of cobalt phosphate co-catalyst in artificial photosynthesis: a theoretical study
Authors: Tsuneda Takao , Ten-no Seiichiro L.
Published: February 2022

The initial water–oxidation reaction mechanism of the hydrated cobalt phosphate (CoPi) co-catalyst, which is consistent with conventional experimental findings, is investigated for O–O bond and OOH formation in this study.
Influence of the crystalline phase on the electrocatalytic behaviour of Sm2−xSrxNiO4−δ (x = 0.4 to 1.0) Ruddlesden–Popper-based systems: a comparative study of bulk and thin electrocatalysts
Authors: Chauhan Manisha , Jha Pardeep K. , Jha Priyanka A. , Singh Prabhakar
Published: February 2022

Compositional effect on OER mechanism of bulk and nano Sm2−xSrxNiO4−δ is studied. Structural phase change altered oxygen non-stoichiometry and therefore OER. With miniaturization, x = 1.0 sample shows conversion from low to moderate electroactivity.
Selective synthesis of the core–shell structured catalyst χ-Fe5C2 surrounded by nanosized Fe3O4 for the conversion of syngas to liquid fuels
Authors: Tang Lei , Zhou Bai-Chuan , Liu Xi , Xu Shuang , Wang Jia , Xu Wei , Liu XiaoHao , Chen Liwei , Lu An-Hui
Published: February 2022

A core–shell structured catalyst χ-Fe5C2 surrounded by nanosized Fe3O4 boosts C5+ hydrocarbon selectivity while suppressing CO2 selectivity.
Exposure to biogenic phosphorus nano-agromaterials promotes early hatching and causes no acute toxicity in zebrafish embryos
Authors: Priyam Ayushi , Singh Pushplata Prasad , Afonso Luis O. B. , Schultz Aaron G.
Published: February 2022

With a growing number of studies now exploring the development of novel phosphorous (P)-based nanomaterials (NMs) for agriculture, there is an increasing concern that these NMs may enter aquatic environments after use and affect aquatic organisms.
Superlattice ordering transitions driven by short-range structure in barium calcium carbonates
Authors: Whittaker Michael. L. , Pri-gal Efrat , Schmidt Asher , Joester Derk
Published: February 2022

Many carbonate superlattices form in nature, including dolomite and norsethite. Here, we show that carbonate superlattice ordering can be driven by short-range structure that is controlled by carbonate ion (re)orientation.
Progresses and future prospects in biodegradation of marine biopolymers and emerging biopolymer-based materials for sustainable marine ecosystems
Authors: Samalens François , Thomas Martin , Claverie Marion , Castejon Natalia , Zhang Yi , Pigot Thierry , Blanc Sylvie , Fernandes Susana C. M.
Published: February 2022

With approximately 250 000 marine species, the ocean is a vast reservoir of biodiversity and an abundant biological resource of natural polymers and microorganisms producing biopolymer-degrading enzymes.
Depth profiling characterization of the titanium chemical state on electrode surfaces for technological applications
Authors: Leani Juan José , Robledo José Ignacio , Oliva Fabiana Yolanda , Sánchez Héctor Jorge
Published: February 2022

EDIXS is used in grazing conditions to determine depth profile of Ti chemical states in surface nanolayers of technological-application films. The outcome can be extended for application to other elements in technological and energy storage materials.
Vasculature-on-a-chip platform with innate immunity enables identification of angiopoietin-1 derived peptide as a therapeutic for SARS-CoV-2 induced inflammation
Authors: Lu Rick Xing Ze , Lai Benjamin Fook Lun , Rafatian Naimeh , Gustafson Dakota , Campbell Scott B. , Banerjee Arinjay , Kozak Robert , Mossman Karen , Mubareka Samira , Howe Kathryn L. , Fish Jason E. , Radisic Milica
Published: February 2022

Microfluidic polymeric blood vessel captures the adverse effects of SARS-CoV-2 on vasculature and enables identification of a therapeutic peptide that abolished virus induced cytokine storm orchestrated by the immune cells.
3D printed microfluidic devices for lipid bilayer recordings
Authors: Ogishi Kazuto , Osaki Toshihisa , Morimoto Yuya , Takeuchi Shoji
Published: February 2022

This paper describes 3D printed microfluidic devices for the rapid implementation of lipid bilayer recordings. We examined 3D printing materials from the perspective of measurement performances and presented feasible applications.
UV-DIB: label-free permeability determination using droplet interface bilayers
Authors: Strutt Robert , Sheffield Felix , Barlow Nathan E. , Flemming Anthony J. , Harling John D. , Law Robert V. , Brooks Nicholas J. , Barter Laura M. C. , Ces Oscar
Published: February 2022

Label-free permeability measurement in droplet interface bilayers to assess the relationship between bilayer lipid composition and permeant chemical structure.
Characterizing the free-energy landscapes of DNA origamis
Authors: Wong Chak Kui , Tang Chuyan , Schreck John S. , Doye Jonathan P. K.
Published: February 2022

We show how coarse-grained modelling combined with umbrella sampling using distance-based order parameters can be applied to compute the free-energy landscapes associated with mechanical deformations of large DNA nanostructures.
Bacterial cellulose-derived micro/mesoporous carbon anode materials controlled by poly(methyl methacrylate) for fast sodium ion transport
Authors: Wang Fujuan , Shi Xiaohong , Zhang Junlei , He Tianqi , Yang Liang , Zhang Tianyun , Ran Fen
Published: February 2022

A carbon anode is prepared from polymer-blended bacterial cellulose by a mild heat-treatment process, and possesses widened interlayer distance, enhanced Na+ diffusion rate, and improved diffusion-controlled capacity.
Engineered mesenchymal stem cell-derived exosomes with high CXCR4 levels for targeted siRNA gene therapy against cancer
Authors: Xu Shuyue , Liu Bin , Fan Junyi , Xue Cuili , Lu Yi , Li Can , Cui Daxiang
Published: February 2022

The mesenchymal stem cells were genetically engineered to obtain exosomes with high CXCR4 expression as carriers for targeted gene-drug delivery.
Dual enhancement of carrier generation and migration on Au/g-C3N4photocatalysts for highly-efficient broadband PET-RAFT polymerization
Authors: Li Mengya , Zhang Junle , He Yanjie , Zhang Xiaomeng , Cui Zhe , Fu Peng , Liu Minying , Shi Ge , Qiao Xiaoguang , Pang Xinchang
Published: February 2022

Broadband photoinduced electron/energy transfer RAFT (PET-RAFT) polymerization was achieved by Au/g-C3N4 complex photocatalysts.
Polymethacrylates containing cage-silsesquioxanes in the side chains: effects of cage and linker structures on film properties
Authors: Igarashi Amato , Imoto Hiroaki , Naka Kensuke
Published: February 2022

Polymers in which cage-silsesquioxanes were tethered through urethane linkers, were newly synthesized. The free-standing films were supported by the hydrogen bonding networks. Their properties were dependent on the cage structure.
Umpolung strategies for the functionalization of peptides and proteins
Authors: White Andrew M. , Palombi Isabella R. , Malins Lara R.
Published: February 2022

This perspective highlights the growing body of literature that leverages polarity reversal (umpolung reactivity) for the selective modification of proteinogenic functionalities and identifies opportunities for further innovation.
Unprecedented mid-infrared nonlinear optical materials achieved by crystal structure engineering, a case study of (KX)P2S6 (X = Sb, Bi, Ba)
Authors: Nguyen Vivian , Ji Bingheng , Wu Kui , Zhang Bingbing , Wang Jian
Published: February 2022

Three superior type-I phase-matching middle infrared nonlinear optical materials (Ea > 4.0 eV, dij > 2× AGS, LDT > 8× AGS) were achieved via crystal structure engineering.
Exploring a new class of singlet fission fluorene derivatives with high-energy triplets
Authors: Mencaroni Letizia , Carlotti Benedetta , Elisei Fausto , Marrocchi Assunta , Spalletti Anna
Published: February 2022

We found that a stronger push–pull character favours SF, as long as the ICT does not act as a trap. The unique property of generating high-energy triplets (ca. 2 eV) via SF makes these materials outstanding candidates for photovoltaic applications.
Summarising the precision statistics from collaborative trials
Authors: Analytical Methods Committee, AMCTB No. 110
Published: February 2022

A collaborative trial (an interlaboratory study) is reputed to be the most reliable way of validating an analytical procedure applied to a defined class of test material, however, the popularity of trials is declining while the need for information from them is escalating.
Molecular mechanisms for the humic acid-enhanced formation of the ordered secondary structure of a conserved catalytic domain in phytase
Authors: Ge Xinfei , Zhang Wenjun , Putnis Christine V. , Wang Lijun
Published: February 2022

We observe an enhanced formation of ordered β-sheet structure through H-bonding between amide groups of active catalytic domain (ACD) in phytase after noncovalently interacting with HA according to Raman and dynamic force microscopy techniques.
The copper sulfate hydration cycle. Crystal structures of CuSO4 (Chalcocyanite), CuSO4·H2O (Poitevinite), CuSO4·3H2O (Bonattite) and CuSO4·5H2O (Chalcanthite) at low temperature using non-spherical atomic scattering factors
Authors: Ibrahim Mukaila A. , Boeré René T.
Published: February 2022

Sky blue CuSO4·3H2O is the midpoint of the copper sulfate hydration cycle. The progression from colourless CuSO4 to bright blue CuSO4·5H2O is intimately linked to the relative number of sulfato versus aqua ligands coordinated to copper.
Service restoration framework for distribution networks incorporating switching crew routing
Authors: Hajizadeh Hamid , Davarpanah Mahdi , Abedini Moein
Published: February 2022

Here, an optimization framework is proposed for the service restoration (SR) problem in distribution networks based on mixed‐integer second‐order cone programming (MISOCP). The objective function is to minimize (i) curtailed loads, (ii) the number of switching operations, (iii) crew dispatching cost, and (iv) operational cost. A novel approach is developed for the optimal switching crew routing (SCR) to perform the manual switching operations in a short time. Self‐healing actions including (i) network reconfiguration, (ii) load shedding, (iii) adjusting the output power of the dispatchable distributed generations (DGs), and (iv) the optimal tap setting of the voltage regulation devices are adopted in the SR strategy. Both the voltage dependency and the uncertainty nature of loads are modelled. Besides, the switch failure scenario is considered in the proposed model to deal with real operating conditions. Hence, the developed optimization framework offers the most robust SR solution. The simulation studies are performed on an actual 87‐bus system in MATLAB/Yalmip environment by adopting Gurobi solver. The obtained results verify that the proposed model enhances quality of the solution in terms of SR process time compared to the other existing models.
A four‐step control for IGBT switching improvement using an active voltage gate driver
Authors: Li Chen , Tan Kun , Ji Bing , Wang Zhiqiang , Ding Shuai , Lefley Paul
Published: February 2022

Gate drivers form an essential interface between the high power transistors and low voltage control circuits in power converters to govern the transistor switching operations and maintain other ancillary functions. A sophisticated gate driver with a segmented drive booster allows optimized trajectories to be staged out during switching transitions, which provides an extended degree of control freedom at the device level. This helps to improve the trade‐offs between multifaceted parameters such as switching losses, overshoots, ringing, and electromagnetic interference, parasitic turn‐on fault, etc. In this paper, a digitalized active gate driver with segmented voltage control is designed and experimentally verified, which is capable of shaping the dynamic switching waveforms of Insulated Gate Bipolar Transistors (IGBT) using a four‐step gate control method. Compared to the traditional constant voltage gate driver method and the three‐step segmented method, the proposed four‐step AVGD control demonstrates reductions of the IGBT turn‐on current overshoot and suppressions of the voltage overshoot on the complementary freewheeling diode without sacrificing its turn‐on switching losses.
Krafttraining mit Kindern und Jugendlichen: die Kniebeuge
Authors: Zawieja Martin
Published: February 2022

Dass für Kinder nicht nur Koordinations- und Ausdauertraining sinnvoll ist, sondern auch ein kindgerechtes Krafttraining, ist inzwischen unbestritten. Die Kniebeuge ist eine gute Übung für den Einstieg.
Forging C–C Bonds through Intramolecular Oxidative Coupling of Organoborates – An Overview
Authors: Didier Dorian
Published: February 2022

C–C bond formation has challenged the community of synthetic organic chemists for decades. Organoboron derivatives represent a mild and functional-group-tolerant class of reagents that can be handled without the need for inert conditions, making them suitable scaffolds for the development of methods that increase the sustainability of current processes for coupling reactions. This short review summarizes the different approaches that have been developed to enable C–C bond formation through intramolecular rearrangements of organoborate species.

1 Introduction

2 Oxidative Coupling with Chemical Oxidants

3 Electrocoupling of Tetraorganoborates

4 Photocoupling of Tetraorganoborates
Dual Role of the Arylating Agent in a Highly C(2)-Selective Pd-Catalysed Functionalisation of Pyrrole Derivatives
Authors: Petkovic Milos , Savic Vladimir , Jovanovic Milos , Jovanovic Predrag , Simic Milena , Tasic Gordana
Published: February 2022

Pyrrole derivatives with C(2)-aryl substituents are an important and widespread class of heterocyclic compounds. Their synthesis can be accomplished using several strategic variants which usually entail either protection of the N–H functionality followed by the arylation, or a direct arylation. Although direct arylation is a preferable process due to a reduced number of synthetic steps, it often requires vigorous conditions or challenging reagents. To this synthetic repertoire, we add a novel method that is based on the dual role of the arylating agent. It serves as the nitrogen protecting group while also being involved in the arylation step. Deprotection as a final stage is carried out simultaneously utilising amines as reacting components. This approach ensures relatively mild conditions and exclusive C(2) selectivity yielding 2-arylpyrroles with the amide functionality. While aromatic amines are not suitable partners under studied conditions, most likely due to lower nucleophilicity, aliphatic amines, either primary or secondary, afford products in good yields.
Palladium-Catalyzed Site-Selective Arylation of α,β-Unsaturated Carbonyl Compounds through a Ligand-Controlled Strategy
Authors: So Chau Ming , Yuen On Ying
Published: February 2022

Palladium-catalyzed direct arylation of α,β-unsaturated carbonyl compounds is an efficient and attractive strategy to access arylated α,β-unsaturated carbonyl compounds through the construction of carbon–carbon bonds. This reaction has several challenges, especially in terms of the control of regioselectivity between α- and γ-arylation and the selectivity for monoarylation and multiple arylation. Herein, we discuss the recent development of γ-arylation of α,β-unsaturated carbonyl compounds and present the ligand-controlled, site-selective α- and γ-arylation of α,β-unsaturated carbonyl ketones with (hetero)aryl halides. The site selectivity of the reaction is switchable by simply changing the phosphine ligand.

1 Introduction

2 Reaction Development and Mechanistic Investigation

3 Conclusion and Outlook
Neurological Patients during the Covid-19 Pandemic
Authors: Salles Débora , Santino Samara Ferreira , Malinverni Andréa Cristina de Moraes , Stávale João Norberto
Published: February 2022

With the current pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), measures of social isolation were necessary, and this resulted in the interruption of several treatments. Regarding neuro-oncological patients, especially those with central nervous system (CNS) disorders, this interruption can cause serious damage or even compromise the success of the treatment in the future. It is essential that each case be evaluated separately to decide how to continue treatment during the pandemic, always considering the risk of SARS-CoV-2 infection and the benefits that the treatment will bring. The policy of not prescribing potentially toxic drugs, chemotherapy, and immunosuppressive therapies, as well as the use of techniques like stereotactic biopsy and telemedicine are important strategies at this time.
Using Duplex Ultrasound for Recipient Vessel Selection
Authors: Hong Joon Pio , Kim Hyung Bae , Park Changsik John , Suh Hyunsuk Peter
Published: February 2022

Background Among the many factors involved in reconstructive microsurgery, identifying a good recipient vessel is one of the key elements leading to a successful result.

Methods Multiple modalities have been used to identify recipient vessels from simple palpation of axial arteries to hand-held Doppler, duplex ultrasound, computed tomography angiograms, and other advanced techniques. Although these various modalities bring their own unique advantages, using the duplex ultrasound can provide far superior and real-time information based on the anatomy and physiology of the recipient vessel.

Results Duplex ultrasound is a valuable and powerful tool for reconstructive surgeons who are interested in performing microsurgery or supermicrosurgery.

Conclusion As we enter the era of individualized/customized reconstruction using superthin flaps, perforator-to-perforator anastomosis, and supermicrosurgery, understanding and becoming versatile with duplex ultrasound will be critical especially in choosing recipient vessels.
Outcomes in Patients with Left Bundle Branch Block after Rapid Deployment Aortic Valve Replacement
Authors: Schlömicher Markus , Useini Dritan , Haldenwang Peter Lukas , Naraghi Hamid , Moustafine Vadim , Bechtel Matthias , Strauch Justus Thomas
Published: February 2022

Objectives Increased rates of postoperative left bundle branch block (LBBB) and permanent pacemaker implantation (PPI) frequently occur after implantation of rapid deployment valves. The impact of LBBB on follow-up outcomes remains controversial. So far, no data regarding long-term outcomes exist.

Aim The aim of this study was to analyze the impact of LBBB on postoperative outcomes after rapid deployment aortic valve replacement (RDAVR).

Methods A total of 620 consecutive patients without preexisting LBBB or PPI who underwent rapid deployment AVR between March 2012 and September 2019 were included. New-onset LBBB was defined as any new LBBB that persisted at hospital discharge. The median follow-up time for clinical data was 1.7 years post-RDAVR.

Results At discharge, new-onset LBBB was seen in 109 patients (17.5%). There were no differences between the LBBB groups and no-LBBB groups regarding baseline characteristics. At a median follow-up of 1.7 years, no difference was found between LBBB groups and no-LBBB groups concerning all-cause mortality (12.8 vs. 11.7%; hazard ratio [HR]: 1.08; 95% confidence interval [CI]: 0.74–1.53; p = 0.54). Nevertheless, new-onset LBBB was associated with significant higher pacemaker implantation rates at follow-up (10.1 vs. 6.3%; HR: 3.58; 95% CI: 1.89–6.81 p < 0.001).

Conclusion After a median follow-up of 1.7 years, new-onset LBBB was not associated with increased mortality. Nevertheless, higher pacemaker implantation rates were observed in patients with new-onset LBBB after RDAVR.
Bedeutung des Einkaufscontrollings: Dashboards im Einkauf - Anwendungsfelder und Potenziale für das Krankenhaus
Authors: Köhler Mathias , Schlüchtermann Jörg
Published: February 2022

Dashboards können im Rahmen des Controllings in Kliniken eine wichtige Rolle einnehmen. Durch die visuelle Darstellung von Key Performance Indicators ermöglichen sie eine effektivere Messung der Unternehmensleistung.
Implantate: Klein, aber fein
Authors: Lang Michael
Published: February 2022

Weltweit arbeiten Wissenschaftler an der Miniaturisierung von aktiven Implantaten. Dabei spielen Lösungen für die Stromversorgung eine wichtige Rolle.
Personalmangel: Jagd nach den jungen Pflegetalenten
Authors: Blöcker Johanna
Published: February 2022

Passgenaue Personalgewinnung und Personalbindung werden im Gesundheitswesen immer wichtiger. Auch die Erwartungen an Arbeitgeber haben sich mit der neuen Generation verändert. Das verdeutlicht eine repräsentative Studie, die Einstellungen und Wünsche von Auszubildenden der Gesundheits- und Krankenpflege gegenüber ihren Arbeitgebern beleuchtet.
Homology-changing percolation transitions on finite graphs
Authors: Woolls Michael , Pryadko Leonid P.
Published: February 2022

We consider homological edge percolation on a sequence (Gt)t of finite graphs covered by an infinite (quasi)transitive graph H and weakly convergent to H. In particular, we use the covering maps to classify 1-cycles on graphs Gt as homologically trivial or non-trivial and define several thresholds associated with the rank of thus defined first homology group on the open subgraphs generated by the Bernoulli (edge) percolation process. We identify the growth of the homological distance dt, the smallest size of a non-trivial cycle on Gt, as the main factor determining the location of homology-changing thresholds. In particular, we show that the giant cycle erasure threshold pE0 (related to the conventional erasure threshold for the corresponding sequence of generalized toric codes) coincides with the edge percolation threshold pc(H) if the ratio dt/ln nt diverges, where nt is the number of edges of Gt, and we give evidence that pE0<pc(H) in several cases where this ratio remains bounded, which is necessarily the case if H is non-amenable.
Multiscale and hierarchical reaction mechanism in a lithium-ion battery
Authors: Orikasa Yuki , Yamamoto Kentaro , Shimizu Takeshi , Uchimoto Yoshiharu
Published: February 2022

The key to improving the performance of lithium-ion batteries is to precisely elucidate the temporal and spatial hierarchical structure of the battery. Lithium-ion batteries consist of cathodes and anodes and a separator containing an electrolyte. The cathodes and anodes of lithium-ion batteries are made of a composite material consisting of an active material, a conductive material, and a binder to form a complex three-dimensional structure. The reaction proceeds as lithium ions are repeatedly inserted into and removed from the active material. Therefore, the lattice of the active material is restructured due to ion diffusion, which results in phase change. At the active material–electrolyte interface, the insertion and de-insertion of lithium ions proceed with the charge transfer reaction. The charge–discharge reaction of a lithium-ion battery is a nonequilibrium state due to the interplay of multiple phenomena. Analysis after disassembling a battery, which is performed in conventional battery research, does not provide an accurate understanding of the dominant factors of the reaction rate and the degradation mechanism, in some cases. This review introduces the results of research on the temporal and spatial hierarchical structure of lithium-ion batteries, focusing on operando measurements taken during charge–discharge reactions. Chapter 1 provides an overview of the hierarchical reaction mechanism of lithium-ion batteries. Chapter 2 introduces the operando measurement technique, which is useful for analysis. Chapter 3 describes the reaction at the electrode–electrolyte interface, which is the reaction field, and Chapter 4 discusses the nonequilibrium structural change caused by the two-phase reaction in the active material. Chapter 5 introduces the study of the unique reaction heterogeneity of a composite electrode, which enables practical energy storage. Understanding the hierarchical reaction mechanism will provide useful information for the design of lithium-ion batteries and next-generation batteries.
Normalized ground states for Kirchhoff equations in R3 with a critical nonlinearity
Authors: Zhang Penghui , Han Zhiqing
Published: February 2022

This paper is concerned with the existence of ground states for a class of Kirchhoff type equations in R3 with combined power nonlinearities −a+b∫R3|∇u(x)|2Δu=λu+|u|p−2u+u5 with the restriction ∫R3u2=c2 in the Sobolev critical case 2* = 6 and proves that the problem has a ground state solution (uc,λc)∈S(c)×R for any c > 0, a, b > 0, and 143≤p<6, where S(c)=u∈H1(R3):∫R3u2=c2.
A large octupole magnetic trap for research with atomic hydrogen
Authors: Ahokas J. , Semakin A. , Järvinen J. , Hanski O. , Laptiyenko A. , Dvornichenko V. , Salonen K. , Burkley Z. , Crivelli P. , Golovizin A. , Nesvizhevsky V. , Nez F. , Yzombard P. , Widmann E. , Vasiliev S.
Published: February 2022

We describe the design and performance of a large magnetic trap for storage and cooling of atomic hydrogen (H). The trap operates in the vacuum space of a dilution refrigerator at a temperature of 1.5 K. Aiming at a large volume of the trap, we implemented the octupole configuration of linear currents (Ioffe bars) for the radial confinement, combined with two axial pinch coils and a 3 T solenoid for the cryogenic H dissociator. The octupole magnet consists of eight race-track segments, which are compressed toward each other with magnetic forces. This provides a mechanically stable and robust construction with a possibility of replacement or repair of each segment. A maximum trap depth of 0.54 K (0.8 T) was reached, corresponding to an effective volume of 0.5 l for hydrogen gas at 50 mK. This is an order of magnitude larger than ever used for trapping atoms.
The joint effect of spin–orbit coupling and atomistic disorder on bandgap evolution in inorganic CsSn1−xPbxI3 mixed perovskite
Authors: Gao Yujia , Luo Tian , Xia Yufan , Chen Yuxuan , Liu Pengyi , Shi Tingting , Xie Weiguang
Published: February 2022

Although the highest power conversion efficiency of an all-inorganic perovskite solar cell has surpassed 20%, the efficiency gap compared with the hybrid perovskite device is still noticeable. The main electronic deficiency of all-inorganic perovskite for improving high efficiency is its larger energy band value. By studying the change of bandgap of inorganic perovskite with the composition ratio, it can help us to optimize the photoelectron performance of perovskite solar devices. Based on first-principles calculations, it is found that the degree of band curvature of the mixed CsSn1−xPbxI3 bandgap is small due to the joint effect of spin–orbit coupling and atomistic disorder, which is different from the bandgap evolution of a hybrid perovskite system. The bandgap bowing parameter gradually augments with an increasing MA+ ratio. Our results indicate that component engineering and electronic structure modulation can optimize the photovoltaic performance appropriately.
Optical isolator based on backward Brillouin scattering
Authors: Ma Sheng-Li , Ren Ya-Long , Cao Ming-Tao , Zhang Shou-Gang , Li Fu-Li
Published: February 2022

We propose to realize an optical isolator based on backward Brillouin scattering in a whispering-gallery-mode (WGM) cavity that supports both traveling optical and acoustic waves. When the WGM cavity is optically driven in one direction, the time-reversal symmetry for light transmission is broken due to the unidirectional photon–phonon coupling. We show that the signal light is either transmitted or completely absorbed depending on whether it propagates in the same or opposite direction as the strong pump laser. The perfect absorption can be interpreted as a phase transition in a parity–time–symmetric Hamiltonian with the balanced gain and loss. The present work paves a way for the realization of an on-chip optical isolator with the high degree of isolation, large bandwidth, and low insertion loss simultaneously.
Analytical modeling and simulation of electrical contact resistance for elastic rough electrode surface contact including frictional temperature rise
Authors: Talukder Sujoy , Yeo Chang-Dong , Hong Yang-Ki , Choi Minyeong , Flicek Robert C. , Bishop Joseph E.
Published: February 2022

An improved electrical contact resistance (ECR) model for elastic rough electrode contact is proposed, incorporating the effects of asperity interactions and temperature rise by frictional and joule heating. The analytical simulation results show that the ECR decreases steeply at the beginning of the contact between Al and Cu. However, it becomes stabilized after reaching a specific contact force. It is also found that the longer elapsed sliding contact time, the higher ECR due to the increase in electrical resistivity of electrode materials by the frictional temperature rise at the interface. The effects of surface roughness parameters on ECR are studied through the 32 full-factorial design-of-experiment analysis. Based on the two representative roughness parameters, i.e., root-mean-square (rms) roughness and asperity radius, their individual and coupled effects on the saturated ECR are examined. The saturated ECR increases with the rms roughness for a rough machined surface condition, but it is hardly affected by the asperity radius. On the other hand, the saturated ECR increases with both the rms roughness and the asperity radius under a smooth thin film surface condition.
Combination of optical emission spectroscopy and multivariate data analysis techniques as a versatile non-invasive tool for characterizing xenon/krypton mixed gas plasma inside operating ion thrusters
Authors: Nauschütt Benny , Chen Limei , Holste Kristof , Klar Peter J.
Published: February 2022

Non-invasive assessment of the plasma parameters is a useful tool for a reliable characterization of many electric thrusters for space applications. Due to high costs, limited availability, and growing use of electric propulsion in spaceflight, alternatives to Xe as a propellant are becoming increasingly important. One option is to use the lighter noble gas krypton or xenon/krypton gas mixtures as a propellant. We propose a versatile analytical approach for establishing empirical correlations between plasma parameters and optical emission (OE) spectroscopy utilizing principal component analysis (PCA). Our approach allows us to establish a surjective mapping of individual OE spectra via their PCA scores onto the corresponding plasma parameters. We prove the feasibility of this approach for Xe, Kr, and Xe/Kr mixed plasmas demonstrating that it is applicable for a wide range of propellant candidates. A major advantage is that the approach does not rely on any microscopic modeling of the OE spectra of the plasma. After having established corresponding reference mappings, the approach can be explored for determining non-invasively and spatially resolved plasma parameters of the propellant plasma of various kinds of operating ion thrusters, which operate in the same plasma regime as the reference plasma. Thus, this method may contribute to shorter qualification and testing times of ion thrusters.
The rheology of ultra-high molecular weight poly(ethylene oxide) dispersed in a low molecular weight carrier
Authors: Mansfied Craig D. , Chen Tianran , Ansari Mubashir Q. , Baird Donald G.
Published: February 2022

Gel spinning is the industrial method of choice for combining hydrophilic ultra-high molecular weight (UHMW) polymer resins with a hydrophobic support polymer to produce composite filaments for cytapheresis. Cytapheresis is a medical technique for removal of leukocytes from blood. Gel spinning is used to avoid high melt viscosity and thermal sensitivity of UHMW resins and the high melt temperature of the substrate resin but requires the recovery of toxic solvents. The UHMW resin is used because it forms a stable gel phase in the presence of water; a lower molecular weight resin (LMW) simply dissolves. UHMW and LMW resins were both poly(ethylene oxide) (PEO) and the substrate was polyarylsulfone (PAS). The literature indicated PEO undergoes non-oxidative thermal degradation above 200 °C and PAS is processed up to 350 °C. Dynamic oscillatory shear rheometry was used to study 0, 25, 40, 50, 60, and 75 wt. % UHMW PEO in LMW PEO to take advantage of the sensitivity of viscosity to changes in molecular weight and material configuration, indicating degradation. Samples were exposed to 220 °C, 230 °C, 240 °C, 250 °C, 275 °C, and 300 °C temperatures for 5 min to explore conditions that could result in sample degradation. The viscosity decreased less with increasing UHMW PEO content for samples exposed to the same temperature and the viscosity decreased more with increasing exposure temperature for samples with the same UHMW PEO content. Parameters were regressed from observed data to predict the change in molecular weight via empiricisms relating the viscosity to molecular weight, shear rate, temperature, and time.
Nonlinear dynamics of electromagnetic field and valley polarization in WSe2 monolayer
Authors: Hashmi Arqum , Yamada Shunsuke , Yamada Atsushi , Yabana Kazuhiro , Otobe Tomohito
Published: February 2022

The linear and nonlinear optical response of a WSe2 monolayer is investigated by a two-dimensional Maxwell plus time-dependent density functional theory with spin–orbit interactions. By applying chiral resonant pulses, the electron dynamics along with high harmonic generation are examined at weak and strong laser fields. The WSe2 monolayer shows linear optical response at the intensity I = 1010 W/cm2, while a complex nonlinear behavior is observed at I = 1012 W/cm2. The nonlinear response of the WSe2 monolayer in terms of saturable absorption is observed at a strong laser field. By changing the chirality of the resonant light, a strong circular dichroic effect is observed in the excited state population. A relatively weak laser field shows effective valley polarization while a strong field induces a spin-polarized carrier peak between K(K′) and Γ-point via a nonlinear process. On the other hand, the strong laser field shows high harmonics up to the 11th order. Our results demonstrate that a circularly polarized resonant pulse generates high harmonics in the WSe2 monolayer of order 3n ± 1.
In situ Raman spectroscopy across superconducting transition of liquid-gated MoS2
Authors: Zhang Yijin , Zhao Dong , Wang Qixing , Smet Jurgen H.
Published: February 2022

Semiconducting group-VI-B transition metal dichalcogenides (TMDs) with the triangular prism crystal structure exhibit unique features. A particularly striking recent example is the observation of an Ising superconducting transition at high carrier densities induced through the field effect in an electric double layer transistor (EDLT). So far, this phenomenon has been accounted for by assuming that the original triangular prismatic bulk crystal structure is unaffected by the heavy doping. However, this assumption has not been verified so far, even though other crystal phases of these layered materials were shown to host Ising superconductivity as well. Here, we provide experimental evidence that the initial triangular prismatic crystal structure of the MoS2, which serves here as a representative member of the TMD family, is not altered during operation of the EDLT even when the carrier density is large enough to induce the superconducting transition. The latter is monitored via transport measurements, while the crystal structure is simultaneously examined in situ with micro-Raman spectroscopy at low temperature.
Formation energy and optical excitation mechanisms of Er in GaN semi-bulk crystals
Authors: Yan Y. Q. , Li J. , Lin J. Y. , Jiang H. X.
Published: February 2022

Erbium (Er) doped GaN (Er:GaN) bulk crystals are promising as an optical gain material for high energy lasers. Other than the preferred configuration of Er3+ occupying the Ga site with four nearest neighbor N atoms (ErGa), Er can also form a complex with a defect (ErGa-DX) in Er:GaN. A set of Er:GaN semi-bulk crystals were grown by hydride vapor phase epitaxy (HVPE) at different growth temperatures to allow the determination of the formation energies, EF, of Er optical centers in Er:GaN. Photoluminescence (PL) emission spectra near 1.5 μm pumped by a near band edge excitation (λexc = 375 nm) and by a resonant excitation (λexc = 980 nm) were measured, which yielded two different formation energies of EF = 2.8 eV and 3.3 eV, corresponding to the formation of ErGa-DX and ErGa in Er:GaN, respectively. As a gain medium, the formation of ErGa-DX in Er:GaN would not only reduce the pumping efficiency of Er optical centers but also increase the optical loss. Our results provide useful insights into possible strategies for enhancing the fraction of ErGa in Er:GaN and, hence, the pumping efficiency, paving the way for achieving optical gain and lasing in Er:GaN.
An E and B gyrokinetic simulation model for kinetic Alfvén waves in tokamak plasmas
Authors: Rosen M. H. , Lu Z. X. , Hoelzl M.
Published: February 2022

The gyrokinetic particle simulation is a powerful tool for studies of transport, nonlinear phenomenon, and energetic particle physics in tokamak plasmas. While most gyrokinetic simulations make use of the scalar and vector potentials, a new model (GK-E&B) has been developed by using the E and B field in a general form and has been implemented in simulating kinetic Alfvén waves in uniform plasma [Chen et al., Sci. China: Phys., Mech. Astron. 64, 245211 (2021)]. In our work, the Chen et al. GK-E&B model has been expressed, in general, tokamak geometry using the local orthogonal coordinates and general tokamak coordinates. Its reduction for uniform plasma is verified, and the numerical results show good agreement with the original work. The theoretical dispersion relation and numerical results in the local model in screw pinch geometry are also in excellent agreement. Numerical results show excellent performance in a realistic parameter regime of burning plasmas with high values of β/(Mek⊥2ρi2), which is a challenge for traditional methods due to the “cancellation” problem. As one application, the GK-E&B model is implemented with kinetic electrons in the local single flux surface limit. With the matched International Tokamak Physics Activity-Toroidicity-induced Alfvén Eigenmodes parameters adopted, numerical results show the capability of the GK-E&B in treating the parallel electron Landau damping for realistic tokamak plasma parameters. As another application, the global GK-E&B model has been implemented with the dominant electron contribution in the cold electron limit. Its capability in simulating the finite E|| due to the finite electron mass is demonstrated.
Temperature dependence of Fano resonances in CrPS4
Authors: Riesner Maurizio , Fainblat Rachel , Budniak Adam K. , Amouyal Yaron , Lifshitz Efrat , Bacher Gerd
Published: February 2022

A Fano resonance, as often observed in scattering, absorption, or transmission experiments, arises from quantum interference between a discrete optical transition and a continuous background. Here, we present a temperature-dependent study on Fano resonances observed in photoluminescence from flakes of the layered semiconductor antiferromagnet chromium thiophosphate (CrPS4). Two Fano resonances with a distinctly different temperature dependence were identified. The continuous background that is responsible for the Fano resonances is attributed to the d–d transition of the optically active Cr3+ center, predominantly the spin-forbidden 2Eg → 4A2g transition with contributions of the broad-band 4T2g → 4A2g transition. The discrete states that interfere with this continuous background are suggested to arise from localized atomic phosphorus. A model idea for explaining the individual temperature dependence of the Fano resonances is presented.
Design of power supply system for the NanChang Spherical Tokamak
Authors: Hou Ming , Qian Y. Z. , Liu S. Q. , Yang X. S. , Chen X. C.
Published: February 2022

The NanChang Spherical Tokamak (NCST), a new compact (plasma major radius R = 0.40 m, minor radius a = 0.24 m, and aspect ratio A = 1.67) spherical tokamak, is suitable for teaching and scientific research activities at the university. The principal goal of the device is to initiate plasma currents by utilizing merging compression. At present, the NCST has a total of five complete coil systems, including the coils and their dedicated power supplies, to generate and control the plasma as per the experimental objectives. This paper presents the NCST device and its coils, the design of the power supplies, and the simulation results of plasma configurations as well as the comparison of experimental and simulation results of the above-mentioned power supply system.
Full extraction of the COM parameters for Rayleigh type surface acoustic wave
Authors: Sun Xueping , Zhou Shun , Cheng Jin , Lin Dabin , Liu Weiguo
Published: February 2022

Extraction of Coupling of Modes (COM) parameters is important in the design of modern high-performance surface acoustic wave (SAW) devices. In this study, we established an effective connection between the COM parameters and the results of stationary and eigenfrequency studies based on the finite element method. Based on this connection, we proposed an approach for fast and full extraction of the COM parameters including the phases of coupling reflection and transduction coefficient. The COM parameters of the commonly used electrode width controlled single-phase unidirectional transducer and bidirectional interdigital transducer cells are computed and compared. It shows that this is a fast, accurate, general, and full extraction of the COM parameters for Rayleigh type SAW.
A data-driven deep learning approach for predicting separation-induced transition of submarines
Authors: Xuan Yang , Lyu Hongqiang , An Wei , Liu Jianhua , Liu Xuejun
Published: February 2022

Separation-induced transitions can affect the hydrodynamic performance of submarines significantly. The onset of this transition plays a critical role in the design of aircrafts and underwater vehicles. Since the transition is affected by various factors, its prediction is a challenging task. Convolutional neural networks (CNNs) in the field of machine learning can extract features from high-dimensional data automatically and have good generalization performance. In this paper, we propose an end-to-end CNN-based model to automatically extract the features of separation-induced transitions by learning from image-expressed flow field data. The proposed data-driven deep learning model employs a high-resolution network, which is widely used in key-point detection in the field of computer vision, to extract the underlying features in the separation-induced transition under only a few empirical assumptions. A novel representation of separation-induced transition onset in the form of a heatmap is especially proposed to indicate the probability of transition onset. We use implicit-large-eddy-simulation data generated by the second-order discontinuous Galerkin method over Lyu's-1 model line submarine to verify the proposed method, and the results demonstrate that the new method is able to predict separation-induced transition onsets with quantified uncertainty. The proposed model can be used as an auxiliary tool for aerodynamic and hydrodynamic designs.
Double-diffusive convection in a rectangular cavity subjected to an external magnetic field with heated rectangular blockage insertion for liquid sodium–potassium alloy
Authors: Kumar Sudhanshu , Gangawane Krunal M.
Published: February 2022

A two-dimensional, steady-state, laminar, double-diffusive convection within the rectangular cavity containing heated rectangular blockage at its geometric center has been explored by the lattice Boltzmann method. The research work is focused on determining the combined influence created by a magnetic force and double-diffusive convective characteristics in the shallow cavity (length > height) and rectangular blockage (width > height). In particular, the influence of various pertinent parameters, such as the aspect ratio of the cavity (AR = 1, 2, and 4), the aspect ratio of the heated blockage (ar = 1, 2, and 4), Lewis number (Le = 2, 5, and 10), Prandtl number (Pr) = 0.054, Rayleigh number (Ra = 103, 104, and 105), Hartmann number (Ha = 0, 50, and 100), and the buoyancy ratios (N = −2, 0, and 2), on the double-diffusive convection accompanied by magnetohydrodynamics characteristics has been elaborated. The working fluid in the cavity is considered to be a liquid metal-sodium–potassium alloy (Pr = 0.054). The results indicated the augmentation in Le leads to the formation of multi-cell zones within the cavity. For N < 0, the direction of fluid flow, thermal, and concentration patterns is reversed as for N > 0. Denser crowding of temperature and concentration contour lines along the block was noticed for N = 2 than N = −2 for a given Ra. The total Nusselt (Nutotal) and Sherwood number (Shtotal) decreases with a decrease in N. The heat and mass transfer rates enhance with augmentation in both cavity and blockage aspect ratios.
Correlated spectral fluctuations quantified by line shape analysis of fifth-order two-dimensional electronic spectra
Authors: Heshmatpour Constantin , Hauer Jürgen , Šanda František
Published: February 2022

Correlated spectral fluctuations were suggested to coordinate excitation transport inside natural light harvesting complexes. We demonstrate the capacities of 2D line shapes from fifth-order coherent electronic signals (R5-2D) to report on such fluctuations in molecular aggregates and present a stochastic approach to fluctuations in correlated site and bi-exciton binding energies in the optical dynamics of Frenkel excitons. The model is applied to R5-2D line shapes of a homodimer, and we show that the peak tilt dynamics are a measure for site energy disorder, inter-site correlation, and the strength of bi-exciton binding energy fluctuations.
Detection of individual spin species via frequency-modulated charge pumping
Authors: Ashton J. P. , Anders M. A. , Ryan J. T.
Published: February 2022

We utilize a frequency-modulated charge pumping methodology to measure quickly and conveniently single “charge per cycle” in highly scaled Si/SiO2 metal–oxide–semiconductor field effect transistors. This is indicative of detection and manipulation of a single interface trap spin species located at the boundary between the SiO2 gate dielectric and Si substrate (almost certainly a Pb type center). This demonstration in sub-micrometer devices in which Dennard scaling of the gate oxide has yielded extremely large gate oxide leakage currents eliminates interference between the charge pumping current and the leakage phenomenon. The result is the ability to measure single trap charge pumping reliably and easily, which would otherwise be completely inaccessible due to oxide leakage. This work provides a unique and readily available avenue for single spin species detection and manipulation, which can be applied as a quantized standard of electrical current as well as to serve as a potentially useful platform for developing quantum engineering technologies. Finally, we discuss potential underlying physical mechanisms that are involved in producing a seemingly contradictory measure of both odd and even integer values for charge per cycle.
The computational fluid dynamics-based epidemic model and the pandemic scenarios
Authors: Dbouk Talib , Drikakis Dimitris
Published: February 2022

This study presents a computational fluid dynamics, susceptible–infected–recovered-based epidemic model that relates weather conditions to airborne virus transmission dynamics. The model considers the relationship between weather seasonality, airborne virus transmission, and pandemic outbreaks. We examine multiple scenarios of the COVID-19 fifth wave in London, United Kingdom, showing the potential peak and the period occurring. The study also shows the importance of fluid dynamics and computational modeling in developing more advanced epidemiological models in the future.