bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of chain reaction driven by proton-coupled electron transfer: α-hydroxyethyl radical and bromoacetate in buffered aqueous solutions
Authors: Sviben Igor , Džeba Iva , Bonifačić Marija , Ljubić Ivan
Published: April 2021

The calculations unravel the role of buffers in the kinetics of the proton-coupled electron transfer reaction between α-hydroxyethyl radical and bromoacetate.
Formation and topological structure of three-dimensional disordered graphene networks
Authors: Wang YongChao , Zhu YinBo , Wu HengAn
Published: April 2021

We provide molecular insights into the formation and topological structure of disordered graphene networks, which would be helpful to understand the microstructure–property relationship of three-dimensional covalently bonded carbon materials.
Tunable electronic properties of BSe–MoS2/WS2 heterostructures for promoted light utilization
Authors: Li Honglin , Ye Lijuan , Xiong Yuanqiang , Zhang Hong , Zhou Shuren , Li Wanjun
Published: April 2021

BSe and MoS2/WS2 have quite low mismatches and intrinsic type-II alignments. The predicted efficiency of the BSe–MoS2 bilayer can be as high as ∼19.3%.
Single-cluster electronics
Authors: Siu Timothy C. , Wong Joshua Y. , Hight Matthew O. , Su Timothy A.
Published: April 2021

This article reviews the scope of inorganic cluster compounds measured in single-molecule junctions. The article explores how the structure and bonding of inorganic clusters give rise to specific quantum transport phenomena in molecular junctions.
Correction: Local structure of a highly concentrated NaClO4 aqueous solution-type electrolyte for sodium ion batteries
Authors: Sakamoto Ryo , Yamashita Maho , Nakamoto Kosuke , Zhou Yongquan , Yoshimoto Nobuko , Fujii Kenta , Yamaguchi Toshio , Kitajou Ayuko , Okada Shigeto
Published: April 2021

Correction for ‘Local structure of a highly concentrated NaClO4 aqueous solution-type electrolyte for sodium ion batteries’ by Ryo Sakamoto et al., Phys. Chem. Chem. Phys., 2020, 22, 26452–26458, DOI: 10.1039/D0CP04376A.
Thermoelectric properties of zinc-doped Cu5Sn2Se7 and Cu5Sn2Te7
Authors: Sturm Cheryl , Macario Leilane R. , Mori Takao , Kleinke Holger
Published: April 2021

The incorporation of Zn in Cu5Sn2Q7 adds one additional electron per formula unit, which results in a narrow band gap semiconductor with improved thermoelectric properties.
Fabrication of monodisperse alginate microgel beads by microfluidic picoinjection: a chelate free approach
Authors: Ahmed Husnain , Stokke Bjørn Torger
Published: April 2021

Monodisperse microgel beads are fabricated by injecting chelate free aqueous Ca2+ in aqueous Na-alginate emulsion and vice versa. This method of producing alginate microbeads without reducing activity of Ca2+ is significant for biological assays.
The non-enzymatic electrochemical detection of glucose and ammonia using ternary biopolymer based-nanocomposites
Authors: Bano Sayfa , Ganie Adil Shafi , Sultana Saima , Khan Mohammad Zain , Sabir Suhail
Published: April 2021

Novel biopolymer-based nanocomposites exhibit significant electrocatalytic activity towards glucose and aqueous ammonia detection with high sensitivity and low detection limits.
Electrospun nanofibrous membranes of cellulose acetate containing hydroxyapatite co-doped with Ag/Fe: morphological features, antibacterial activity and degradation of methylene blue in aqueous solution
Authors: Shalan Ahmed Esmail , Afifi Mohamed , El-Desoky M. M. , Ahmed M. K.
Published: April 2021

Cellulose acetate nanofiber membranes containing hydroxyapatite co-doped with Ag/Fe are effective towards the degradation of MB dye in aqueous solutions.
Effect of charge storage engineering on the NO2 gas sensing properties of a WO3 FET-type gas sensor with a horizontal floating-gate
Authors: Shin Wonjun , Hong Seongbin , Jeong Yujeong , Jung Gyuweon , Park Jinwoo , Kim Donghee , Lee Chayoung , Park Byung-Gook , Lee Jong-Ho
Published: April 2021

By setting the FET transducer to be in the erase state, its ΔVFG and response can be modulated by ∼4 and 100 times, respectively. Also, the sensitivity can be improved by a factor of ∼3.
Diethylammonium iodide as catalyst for the metal-free synthesis of 5-aryl-2-oxazolidinones from aziridines and carbon dioxide
Authors: Bresciani Giulio , Bortoluzzi Marco , Pampaloni Guido , Marchetti Fabio
Published: April 2021

A series of 5-aryl-2-oxazolidinones was efficiently obtained from aziridine precursors with smallN-alkyl substituentsviaCO2fixation under ideal experimental conditions, using a simple ammonium salt as catalyst.
Micrometer-scale transient ion transport for real-time pH assay in living rat brains
Authors: Zhang Kailin , Wei Huan , Xiong Tianyi , Jiang Yanan , Ma Wenjie , Wu Fei , Yu Ping , Mao Lanqun
Published: April 2021

Micrometer-scale transient ion transport has been successfully used for constructing a high spatiotemporal resolution and performance microsensor, which could be used for real-time monitoring the change of pH in rat brains.
FOXP4-AS1 is a favorable prognostic-related enhancer RNA in ovarian cancer
Authors: Hua Tian , Tian Yun-jie , Wang Rui-min , Zhao Cai-fen , Kong Yun-hong , Tian Rui-qing , Wang Wei , Ma Li-xia
Published: April 2021

Ovarian cancer (OV) is the main cause of deaths worldwide in female reproductive system malignancies. Enhancer RNAs (eRNAs) are derived from the transcription of enhancers and has attracted increasing attention in cancers recently. However, the biological functions and clinical significance of eRNAs in OV have not been well described presently. We used an integrated data analysis to identify prognostic-related eRNAs in OV. Tissue-specific enhancer-derived RNAs and their regulating genes were considered as putative eRNA–target pairs using the computational pipeline PreSTIGE. Gene expression profiles and clinical data of OV and 32 other cancer types were obtained from the UCSC Xena platform. Altogether, 71 eRNAs candidates showed significant correlation with overall survival (OS) of OV samples (Kaplan–Meier log-rank test, P<0.05). Among which, 23 were determined to be correlated with their potential target genes (Spearman’s r > 0.3, P<0.001). It was found that among the 23 prognostic-related eRNAs, the expression of forkhead box P4 antisense RNA 1 (FOXP4-AS1) had the highest positive correlation with its predicted target gene FOXP4 (Spearman’s r = 0.61). Moreover, the results were further validated by RT-qPCR analysis in an independent OV cohort. Our results suggested the eRNA FOXP4-AS1 expression index may be a favorable independent prognostic biomarker candidate in OV.
Forensic botany: time to embrace natural history collections, large scale environmental data and environmental DNA
Authors: Spencer Mark A.
Published: April 2021

Forensic botany is a diverse discipline that spans many aspects of plant sciences, particularly taxonomy, field botany, anatomy, and ecology. Internationally, there is a significant opportunity to expand the application of forensic botany in criminal investigations, especially war crimes, genocide, homicide, sexual violence, serious physical assault, illegal trade in endangered species and wildlife crime. In civil proceedings, forensic botany may, for example, be called upon in trade disputes such as accidental contamination of commodities. Despite the potential, there are barriers to the wider application of forensic botany in criminal cases; there is a widespread need to improve the efficiency of botanical trace evidence identification. This could partly be addressed by embracing innovations in image recognition and by accessing the huge quantity of specimens and images housed in natural history collections worldwide. Additionally, the recent advances in DNA sequencing technologies and the expansion of environmental DNA (eDNA) and forensic ecogenomics, offers opportunities to more rapidly provide species-level identifications. The impact of taphonomic processes upon vegetation, and vice versa, remains poorly understood; improved understanding of these interactions and their ecological impacts may be invaluable in improving clandestine burial search protocols.
An Evaluation of Simulation Techniques in Audiology and Allied Health Professions
Authors: Andre Alexandra , Reed Amanda , Ananthakrishnan Saradha , Korczak Peggy
Published: April 2021

Purpose

This study aims to investigate the experiences and opinions of clinical educators from various allied health care fields, including audiology, related to the use of simulation as a teaching technique and determine the status of clinical simulation techniques in training audiology graduate students nationwide.

Method

An interview was conducted with nine faculty members in the College of Health Professions at Towson University to discuss advantages and challenges of incorporating clinical simulation techniques into student learning. A thematic analysis was used to analyze the interview responses. Additionally, a web-based questionnaire was sent to all audiology graduate program directors nationwide, yielding a response rate of 63%. These data were analyzed using descriptive statistics.

Results

Interview responses revealed a number of benefits and barriers related to simulation use at the graduate level. Benefits included its use as a learning tool, a quality control measure, and an aid in professional development. It also increases students' confidence levels in clinical procedures and counseling skills and exposes them to a variety of clinical pathologies not routinely seen. Barriers included lack of training with simulators, lack of funding to purchase simulator technology, and lack of resources, such as time and space. At present, only 50% of audiology program directors reported using clinical simulation to train their students.

Conclusions

The field of audiology is embracing simulation techniques in training its preprofessional work force. To date, there has been limited guidance from professional organizations regarding the role of simulation in audiology. Additional assistance focusing on best practices for these techniques is warranted.
Measuring the masses and radii of neutron stars in low-mass X-ray binaries: Effects of the atmospheric composition and touchdown radius
Authors: Kim Myungkuk , Kim Young-Min , Sung Kwang Hyun , Lee Chang-Hwan , Kwak Kyujin
Published: April 2021

Context. X-ray bursts (XRBs) are energetic explosive events that have been observed in low-mass X-ray binaries (LMXBs). Some Type-I XRBs exhibit photospheric radius expansion (PRE) and these PRE XRBs are used to simultaneously estimate the mass and the radius of a neutron star in LMXB.

Aims. The mass and radius estimation depends on several model parameters, most of which are still uncertain. Here, we focus on the effects of the chemical composition of the photosphere, which determines the opacity during the PRE phase, and the touchdown radius, which can be larger than the neutron star radius. We investigate how these two model parameters affect the mass and radius estimation in a systematic way and whether there is any statistical trend for these two parameters as well as whether there is a possible correlation between them.

Methods. We used both a Monte Carlo (MC) sampling and a Bayesian analysis to examine the effects of the photospheric composition and the touchdown radius. We applied these two methods to six LMXBs exhibiting PRE XRBs. With both methods, we solved the Eddington flux equation and the apparent angular area equation, both of which include the correction terms. For the MC sampling, we developed an iterative method in order to solve these two equations more efficiently.

Results. We confirm that the effects of the photospheric composition and the touchdown radius are similar in the statistical and analytical estimation of mass and radius, even when the correction terms are considered. Furthermore, in all of the six sources, we find that a H-poor photosphere and a large touchdown radius are favored statistically regardless of the statistical method. Our Bayesian analysis also hints that touchdown can occur farther from the neutron star surface when the photosphere is more H-poor. This correlation could be qualitatively understood with the Eddington flux equation. We propose a physical explanation for this correlation between the photospheric composition and the touchdown radius. Our results show that when accounting for the uncertainties of the photospheric composition and the touchdown radius, it is most likely that the radii of the neutron stars in these six LMXBs are less than 12.5 km. This value is similar to that of the bounds placed on the neutron star radius based on the tidal deformability measured from the gravitational wave signal.
Magnetic and tidal migration of close-in planets
Authors: Ahuir J. , Strugarek A. , Brun A.-S. , Mathis S.
Published: April 2021

Context.Over the last two decades, a large population of close-in planets has been detected around a wide variety of host stars. Such exoplanets are likely to undergo planetary migration through magnetic and tidal interactions.

Aims.We aim to follow the orbital evolution of a planet along the structural and rotational evolution of its host star, simultaneously taking into account tidal and magnetic torques, in order to explain some properties of the distribution of observed close-in planets.

Methods.We rely on a numerical model of a coplanar circular star–planet system called ESPEM, which takes into account stellar structural changes, wind braking, and star–planet interactions. We browse the parameter space of the star–planet system configurations and assess the relative influence of magnetic and tidal torques on its secular evolution. We then synthesize star–planet populations and compare their distribution in orbital and stellar rotation periods toKeplersatellite data.

Results.Magnetic and tidal interactions act together on planetary migration and stellar rotation. Furthermore, both interactions can dominate secular evolution depending on the initial configuration of the system and the evolutionary phase considered. Indeed, tidal effects tend to dominate for high stellar and planetary masses as well as low semi-major axis; they also govern the evolution of planets orbiting fast rotators while slower rotators evolve essentially through magnetic interactions. Moreover, three populations of star–planet systems emerge from the combined action of both kinds of interactions. First, systems undergoing negligible migration define an area of influence of star–planet interactions. For sufficiently large planetary magnetic fields, the magnetic torque determines the extension of this region. Next, planets close to fast rotators migrate efficiently during the pre-main sequence, which engenders a depleted region at low rotation and orbital periods. Then, the migration of planets close to slower rotators, which happens during the main sequence, may lead to a break in gyrochronology for high stellar and planetary masses. This also creates a region at high rotation periods and low orbital periods not populated by star–planet systems. We also find that star–planet interactions significantly impact the global distribution in orbital periods by depleting more planets for higher planetary masses and planetary magnetic fields. However, the global distribution in stellar rotation periods is marginally affected, as around 0.5% of G-type stars and 0.1% of K-type stars may spin up because of planetary engulfment. More precisely, star–planet magnetic interactions significantly affect the distribution of super-Earths around stars with a rotation period higher than around 5 days, which improves the agreement between synthetic populations and observations at orbital periods of less than 1 day. Tidal effects for their part shape the distribution of giant planets.
Forever young white dwarfs: When stellar ageing stops
Authors: Camisassa María E. , Althaus Leandro G. , Torres Santiago , Córsico Alejandro H. , Rebassa-Mansergas Alberto , Tremblay Pier-Emmanuel , Cheng Sihao , Raddi Roberto
Published: April 2021

White dwarf stars are the most common end point of stellar evolution. The ultramassive white dwarfs are of special interest as they are related to type Ia supernovae explosions, merger events, and fast radio bursts. Ultramassive white dwarfs are expected to harbour oxygen-neon (ONe) cores as a result of single standard stellar evolution. However, a fraction of them could have carbon-oxygen (CO) cores. Recent studies, based on the new observations provided by the Gaia space mission, indicate that a small fraction of the ultramassive white dwarfs experience a strong delay in their cooling, which cannot be solely attributed to the occurrence of crystallisation, thus requiring an unknown energy source able to prolong their life for long periods of time. In this study, we find that the energy released by 22Ne sedimentation in the deep interior of ultramassive white dwarfs with CO cores and high 22Ne content is consistent with the long cooling delay of these stellar remnants. On the basis of a synthesis study of the white dwarf population, based on Monte Carlo techniques, we find that the observations revealed by Gaia can be explained by the existence of these prolonged youth ultramassive white dwarfs. Although such a high 22Ne abundance is not consistent with the standard evolutionary channels, our results provide evidence for the existence of CO-core ultramassive white dwarfs and for the occurrence of 22Ne sedimentation.
Die moderne Orthokeratologie – scharf sehen über
Nacht
Authors: Ring-Mangold Theresia , Emminger Ralf
Published: April 2021

Ohne Sehhilfe durchs Leben zu gehen – ein durchaus realistischer Traum. In der
Liga der refraktiven Korrekturoptionen spielt die Orthokeratologie ihre sehr
eigene Rolle. Das Prinzip: Eine hoch gaspermeable, formstabile Kontaktlinse, die
nachts während des Schlafs getragen wird, verändert durch ihre spezielle
Geometrie die Radien der Cornea reversibel in genau der Art und Weise, dass die
Refraktion des Auges tagsüber unkorrigiert der Emmetropie nahekommt.
Extraction and Fractionation Effects on Antiplasmodial Activity and Phytochemical Composition of Palicourea hoffmannseggiana
Authors: Ohashi Leticia Hiromi , Gontijo Douglas Costa , Nascimento Maria Fernanda Alves do , Margalho Luciano Ferreira , Brandão Geraldo Célio , Oliveira Alaíde Braga de
Published: April 2021

The present study on Palicourea hoffmannseggiana, which was collected at Marapanim, state of Pará, Brazil, comprises the preparation of different stem and leaf extracts and fractions. Ethanol, hydroethanol, and water extracts were prepared by several methods and evaluated for in vitro activity against resistant Plasmodium falciparum (W2 strain), disclosing a low parasite growth inhibition effect (< 50%). Dereplication by UPLC-DAD-ESI−MS of the leaf ethanol extract showed the presence of two known alkaloids, lyalosidic and strictosidinic acids, along with a sinapoyl ester of lyalosidic acid, with m/z 719.33 [M+H]+, which is possibly a new monoterpene indole alkaloid representative. Sequential liquid-liquid acid-base alkaloid separations from the leaf ethanol extract as well as directly from leaf powder afforded fractions of increased parasite growth inhibition, reaching up to 92.5±0.7%. The most bioactive fractions were shown to contain the β-carboline alkaloids harmane and 4-methyl-β-carboline, along with N-methyl-tryptamine and N-acetyl-tryptamine, while monoterpene indole alkaloids were detected in inactive fractions of these processes. The present results demonstrate that these preliminary fractionation methods can lead to significantly active fractions supporting an adequate scale-up to carrying out the isolation of anti-plasmodial compounds.
Triterpene Profiling of Neem Exudate (Toddy) Using UHPLC-QTOF-MS and
its Anti-inflammatory Activity
Authors: Biswal Ranendra Pratap , Patnana Durga Prasad , Pulukool Sujith Kumar , Sivaramakrishnan Venketesh , Pargaonkar Ashish , Dandamudi Rajesh Babu
Published: April 2021

Neem tree (Azadirachta indica) is one of the richest sources of
secondary metabolites. More than 250 natural products have been
characterized from various parts of the neem tree. These include
diterpenoids, triterpenoids, steroids, flavonoids, coumarins, hydrocarbons,
and fatty acids. Many of these products possess therapeutic properties. Neem
exudate or toddy is a milky white liquid with a strong smell secreted from
the angle between the 2 main branches of old trees. Profiling of neem toddy
for the presence of active metabolites was done by an in-house database
using UHPLC-QTOF-MS. Fifty-seven metabolites were identified from the full
scan of electrospray ionization positive and negative mode from the neem
toddy extract by using UHPLC-QTOF-MS. Further confirmation of 31 of these
metabolites was done by obtaining MS/MS spectrum from UHPLC-QTOF-MS.
Principal component analysis study of metabolites from neem toddy with
leaves, seed, seed coat, and bark revealed that they are closely related to
those contained in neem seeds and seed coats. Azadirachtin, nimbidiol,
22,23-dihydroazadirachtin, nimbonone, nimbonolone, nimosone, and
6-deacetylnimbinene were found to be some of the most abundant metabolites
in neem toddy. The neem toddy extract showed significant anti-inflammatory
activity when tested in N9 murine microglial cells with 25 ng of recombinant
mouse tumor necrosis factor alpha protein (active) using qRT-PCR. The active
metabolites in neem toddy could be further explored for their therapeutic
potentials.
Crosslinking und Keratokonus
Authors: Lang Stefan J. , Maier Philip , Reinhard Thomas
Published: April 2021

Ein Keratokonus führt zu einer progressiven Vorwölbung und Verdünnung der Hornhaut. Um dies aufzuhalten, kann ein Crosslinking durchgeführt werden. Dabei ist eine Behandlung nach dem „Dresdener Protokoll“ eine effektive und sichere Behandlungsmöglichkeit, aber auch zahlreiche neue Anwendungsprotokolle (akzeleriertes Crosslinking, transepitheliales Crosslinking) und sogar weitere Indikationen (refraktive Eingriffe, infektiöse Keratitis) wurden in den letzten Jahren veröffentlicht.
Die moderne Orthokeratologie – scharf sehen über Nacht
Authors: Ring-Mangold Theresia , Emminger Ralf
Published: April 2021

Ohne Sehhilfe durchs Leben zu gehen – ein durchaus realistischer Traum. In der Liga der refraktiven Korrekturoptionen spielt die Orthokeratologie ihre sehr eigene Rolle. Das Prinzip: Eine hoch gaspermeable, formstabile Kontaktlinse, die nachts während des Schlafs getragen wird, verändert durch ihre spezielle Geometrie die Radien der Cornea reversibel in genau der Art und Weise, dass die Refraktion des Auges tagsüber unkorrigiert der Emmetropie nahekommt.
Transition-Metal-Catalyzed C–H Arylation Using Organoboron Reagents
Authors: Maiti Debabrata , Basak Sumon , Biswas Jyoti Prasad
Published: April 2021

Aryl rings are ubiquitous in the core of numerous natural product and industrially important molecules and thus their facile synthesis is of major interest in the scientific community and industry. Although multiple strategies enable access to these skeletons, metal-catalyzed C–H activation is promising due to its remarkable efficiency. Commercially available organoboron reagents, a prominent arylating partner in the cross-coupling domain, have also been utilized for direct arylation. Organoborons are bench-stable, inexpensive, and readily available coupling partners that promise regioselectivity, chemodivergence, cost-efficiency, and atom-economy without requiring harsh and forcing conditions. This critical, short review presents a summary of all major studies of arylation using organoborons in transition-metal catalysis since 2005.

1 Introduction

2 Arylation without Directing Group Assistance

2.1 Palladium Catalysis

2.2 Iron Catalysis

2.3 Gold Catalysis

3 Arylation with Directing Group Assistance

3.1 Palladium Catalysis

3.2 Ruthenium Catalysis

3.3 Rhodium Catalysis

3.4 Nickel Catalysis

3.5 Cobalt Catalysis

3.6 Copper Catalysis

4 Conclusion
Obesity and the Risk of Infertility, Gestational Diabetes, and Type 2 Diabetes in Polycystic Ovary Syndrome
Authors: Pirotta Stephanie , Joham Anju , Grieger Jessica A. , Tay Chau Tien , Bahri-Khomami Mahnaz , Lujan Marla , Lim Siew S. , Moran Lisa J.
Published: April 2021

This review describes the relationship between obesity and the most common reproductive (infertility) and metabolic (gestational diabetes mellitus [GDM] and type 2 diabetes mellitus [T2DM]) consequences in polycystic ovary syndrome (PCOS). It also describes the vital role of lifestyle management for PCOS. PCOS is a heterogeneous endocrine disorder common in reproductive-age women. Consensus on the exact etiological mechanisms of PCOS is unreached. Overweight or obesity is present in at least 60% of the PCOS population, but the condition occurs irrespective of BMI, with excess BMI increasing both the prevalence and severity of clinical features. Use of lifestyle therapies (nutrition, physical activity, and/or behavioral) for the prevention and management of excess weight gain, infertility, GDM, and T2DM is a vital component of best-practice PCOS care. Lifestyle management is recommended for all women with PCOS as the first-line treatment with or without medications. Due to a lack of high-quality trials demonstrating the efficacy of specific lifestyle approaches, PCOS lifestyle recommendations are as those for the general population. This review summarizes current knowledge relating to obesity and its impact on fertility, GDM, and T2DM. It also summarizes the lifestyle recommendations to best manage these conditions in women with PCOS and obesity.
Hydrogen fuel conversion can be improved in bismuth vanadate
Authors: Lim Alane
Published: April 2021

Strain can improve bismuth vanadate’s production of clean energy.
Topology identification of fractional-order complex dynamical networks based on auxiliary-system approach
Authors: Zheng Yi , Wu Xiaoqun , He Guoliang , Wang Wei
Published: April 2021

Many practical systems can be well described by various fractional-order equations. This paper focuses on identifying the topology of the response layer of a drive-response fractional-order complex dynamical network using the auxiliary-system approach. Specifically, the response layer and the auxiliary layer receive the same input signals from the drive layer. By a designed adaptive control law, the unknown topology of the response layer is successfully identified. Moreover, the proposed method is effective even if the drive layer is made up of isolated nodes. The correctness of the theoretical results is demonstrated by numerical simulations.
Nonlinear description of quantum dynamics: Generalized coherent states
Authors: Cruz-Prado H. , Marmo G. , Schuch D. , Castaños O.
Published: April 2021

In this work, it is shown that there is an inherent nonlinear evolution in the dynamics of the so-called generalized coherent states. To show this, the immersion of a classical manifold into the Hilbert space of quantum mechanics is employed. Then, one may parameterize the time dependence of the wave function through the variation of parameters in the classical manifold. Therefore, the immersion allows us to consider the so-called principle of analogy, i.e., using the procedures and structures available from the classical setting to employ them in the quantum framework.
Non-volatile voltage control of in-plane and out-of-plane magnetization in polycrystalline Ni films on ferroelectric PMN–PT (001)pc substrates
Authors: Ghidini M. , Ye F. , Steinke N.-J. , Mansell R. , Barnes C. H. W. , Mathur N. D.
Published: April 2021

We identify room-temperature converse magnetoelectric effects (CMEs) that are non-volatile by using a single-crystal substrate of PMN–PT (001)pc (pc denotes pseudocubic) to impart voltage-driven strain to a polycrystalline film of Ni. An appropriate magnetic-field history enhances the magnetoelectric coefficient to a near-record peak of ∼10−6 s m−1 and permits electrically driven magnetization reversal of substantial net magnetization. In zero magnetic field, electrically driven ferroelectric domain switching produces large changes of in-plane magnetization that are non-volatile. Microscopically, these changes are accompanied by the creation and destruction of magnetic stripe domains, implying the electrical control of perpendicular magnetic anisotropy. Moreover, the stripe direction can be rotated by a magnetic field or an electric field, the latter yielding the first example of electrically driven rotatable magnetic anisotropy. The observed CMEs are associated with repeatable ferroelectric domain switching that yields a memory effect. This memory effect is well known for PMN–PT (110)pc but not PMN–PT (001)pc. Given that close control of the applied field is not required as for PMN–PT (110)pc, this memory effect could lead the way to magnetoelectric memories based on PMN–PT (001)pc membranes that switch at low voltage.
Phase evolution during annealing of low-temperature co-evaporated precursors for CZTSe solar cell absorbers
Authors: Mwakyusa Lwitiko P. , Jin Xiaowei , Müller Erich , Schneider Reinhard , Gerthsen Dagmar , Rinke Monika , Paetzold Ulrich W. , Richards Bryce S. , Hetterich Michael
Published: April 2021

Systematic investigations into the phase evolution during reactive annealing of copper–zinc–tin–selenide (CZTSe) precursors for the fabrication of kesterite solar cell absorber layers have been paramount in understanding and suppressing the formation of secondary phases that deteriorate device performance. In this study, the phase evolution during annealing of low-temperature co-evaporated CZTSe precursors is investigated. A detailed analysis of films selenized at different temperatures is used to reveal the possible reaction pathway of CZTSe formation. Utilizing a combination of x-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive x-ray spectroscopy, it is shown that CZTSe formation starts by Cu out-diffusion to the surface and Cu–Se phase formation at a temperature of 350 °C. An intimate mixing of binaries and ternaries during low-temperature selenization is observed. On the contrary, only binaries are observed at high-temperature selenization. This suggests that the CZTSe formation pathway involves reaction schemes where (i) a competition between binary and ternary phases dominates at low-temperature and (ii) binary reactions dominate the process at high temperatures. However, the number of binary phases decreases with increasing selenization temperature until they become undetectable by XRD and Raman spectroscopy at a temperature of 540 °C (selenization time 10 min). Utilizing the presented selenization conditions, prototype solar cells with an efficiency of up to 7.5%, an open-circuit voltage of 407 mV, and a fill factor of 59%, could be demonstrated. The temperature-dependent current density–voltage characteristics indicate that the performance of the prototype devices is limited by bulk Schottky–Read–Hall recombination.
Nonlinear coupling of whistler waves to oblique electrostatic turbulence enabled by cold plasma
Authors: Roytershteyn Vadim , Delzanno Gian Luca
Published: April 2021

Kinetic simulations and theory demonstrate that whistler waves can excite oblique, short-wavelength fluctuations through secondary drift instabilities if a population of sufficiently cold plasma is present. The excited modes lead to heating of the cold populations and damping of the primary whistler waves. The instability threshold depends on the density and temperature of the cold population and can be relatively small if the temperature of the cold population is sufficiently low. This mechanism may thus play a significant role in controlling amplitude of whistlers in the regions of the Earth's magnetosphere where cold background plasma of sufficient density is present.
Strained interface layer contributions to the structural and electronic properties of epitaxial V2O3 films
Authors: Hajihoseini Hamidreza , Thorsteinsson Einar B. , Sigurjonsdottir Vilborg V. , Arnalds Unnar B.
Published: April 2021

We report on the transport properties of epitaxial vanadium sesquioxide (V2O3) thin films with thicknesses in the range of 1 to 120 nm. Films with the thickness down to nanometer values reveal clear resistivity curves with temperature illustrating that even at these thicknesses, the films are above the percolation threshold and continuous over large distances. The results reveal that with the reducing thickness, the resistivity of the films increases sharply for thicknesses below 4 nm and the metal-insulator transition (MIT) is quenched. We attribute this increase to a strained interface layer of thickness ∼4 nm with in-plane lattice parameters corresponding to the Al2O3 substrate. The interface layer displays a suppressed MIT shifted to higher temperatures and has a room temperature resistivity 6 orders of magnitude higher than the thicker V2O3 films.
Hard x-ray photoemission study on strain effect in LaNiO3 thin films
Authors: Yamagami K. , Ikeda K. , Hariki A. , Zhang Y. , Yasui A. , Takagi Y. , Hotta Y. , Katase T. , Kamiya T. , Wadati H.
Published: April 2021

The strain effect from a substrate is an important experimental route to control electronic and magnetic properties in transition-metal oxide (TMO) thin films. Using hard x-ray photoemission spectroscopy, we investigate the strain dependence of the valence states in LaNiO3 thin films, strongly correlated perovskite TMO, grown on four substrates: LaAlO3, (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7, SrTiO3, and DyScO3. A Madelung potential analysis of core-level spectra suggests that the point-charge description is valid for the La ions, while it breaks down for Ni and O ions due to a strong covalent bonding between the two. A clear x-ray photon-energy dependence of the valence spectra is analyzed by the density functional theory, which points to the presence of the La 5p state near the Fermi level.
A double gimbal optical image stabilizer driven by piezoelectric stacks
Authors: Xu Zhangfan , Pan Song , Chen Lei , Xiao Zhong
Published: April 2021

With the advantages of high accuracy and fast response, piezoelectric actuators are used to drive optical image stabilizers. As a piezoelectric stack is not tensile, preload voltage is required for a traditional piezoelectric driven optical image stabilizer, which wastes electricity and adversely affects the stack’s performance. In this paper, we propose a double gimbal optical image stabilizer, whereupon a prototype is machined and its performance is assessed. Two piezoelectric stacks are used to produce the forward and reverse actuation, respectively, in which case the preload voltage is not essential. Owing to the isolation of the gimbal, the output coupling of the two piezoelectric actuators is less than 1%. The presented stabilizer has the actuation range of ±50 µm and effectively tracks the sinusoidal signals with the frequency below 46 Hz.
Determination of the Fermi velocity of graphene on MoS2 using dual mode scanning tunneling spectroscopy
Authors: Jiao Zhen , Zandvliet Harold J. W.
Published: April 2021

We have measured the Fermi velocity of graphene on MoS2 using dual mode scanning tunneling spectroscopy. In our method, the tunnel current (I) and the derivate of the current to the gap width (dI/dz) are measured simultaneously as a function of sample bias (V) at a constant tip-substrate distance. Owing to the difference in lattice constants between graphene (2.461 Å) and MoS2 (3.161 Å), a moiré structure is found with a periodicity of 1.07 nm and a twist angle of 4°. Our experiments reveal that the electronic band structure of graphene remains intact in the bandgap region of MoS2. The Fermi velocity of graphene on MoS2 is determined to be 1.2±0.1×106 m/s.
Investigation on band alignment of Bi2Se3–PbSe heterojunction
Authors: Ren Yixuan , Li Yuqi , Liu Xingzhao
Published: April 2021

In this Letter, in situ growth of the Bi2Se3–PbSe heterojunction was achieved by the molecular beam epitaxy process. An atomically abrupt heterointerface was observed. The band alignment configuration of the Bi2Se3–PbSe heterojunction was investigated by x-ray photoelectron spectroscopy. A broken (type-III) energy band discontinuity with the valence band offset of 0.4 eV at the heterointerface was determined. This result might broaden the application prospect of Bi2Se3 in the future development of optoelectronics.
Interatomic potential for predicting the thermal conductivity of zirconium trisulfide monolayers with molecular dynamics
Authors: Saiz Fernan , Karaaslan Yenal , Rurali Riccardo , Sevik Cem
Published: April 2021

We present here a new interatomic potential parameter set to predict the thermal conductivity of zirconium trisulfide monolayers. The generated Tersoff-type force field is parameterized using data collected with first-principles calculations. We use non-equilibrium molecular dynamics simulations to predict the thermal conductivity. The generated parameters result in very good agreement in structural, mechanical, and dynamical parameters. The room temperature lattice thermal conductivity (κ) of the considered crystal is predicted to be κxx = 25.69 W m−1 K−1 and κyy = 42.38 W m−1 K−1, which both agree well with their corresponding first-principles values with a discrepancy of less than 5%. Moreover, the calculated κ variation with temperature (200 and 400 K) are comparable within the framework of the accuracy of both first-principles and molecular dynamics simulations.
A general single-node second-order boundary condition for the lattice Boltzmann method
Authors: Chen Yong , Wang Xiangyang , Zhu Hanhua
Published: April 2021

In this work, we propose a general single-node nonslip hydrodynamic boundary condition for the lattice Boltzmann method. The construction of the boundary scheme is the combination of the bounce back rule for the nonequilibrium part of the density distribution and linear interpolation. The proposed boundary condition is very simple, universal, stable, and accurate. The asymptotic analysis of the newly proposed boundary condition confirms that is of second-order accuracy. The numerical experiments demonstrate that the boundary condition is indeed second-order accurate for both straight and curved boundaries.
Parasitic p–n junctions formed at V-pit defects in p-GaN
Authors: Vergeles P. S. , Yakimov E. B. , Polyakov A. Y. , Shchemerov I. V. , Chernykh A. V. , Vasilev A. A. , Kochkova A. I. , Lee In-Hwan , Pearton Stephen J.
Published: April 2021

The luminescent and recombination properties of V-pit defects in p-GaN(Mg) grown by metalorganic chemical vapor deposition (MOCVD) were studied by scanning electron microscopy (SEM) in the secondary electron, cathodoluminescence (CL), and electron beam induced current (EBIC) modes, combined with CL spectra measurements and EBIC collection efficiency measurements. Similar studies were performed on low-dislocation-density freestanding n-GaN crystals. For MOCVD p-GaN films, the SEM investigations were supplemented by capacitance–voltage, current–voltage, deep level transient spectroscopy analysis with Ni Schottky diode, and Ohmic contacts. These experiments show that V-pits in p-GaN increase the leakage current of Schottky diodes, as in n-GaN films and crystals. EBIC imaging and EBIC collection efficiency results suggest that in the region of V-pits, a parasitic p–n junction is formed. We also observe that, in V-pits, the CL spectra the contribution of the 3.2 eV defect band is strongly enhanced compared to the 3 eV blue CL band that dominates the spectra.
Multiple-sound-source-excitation quartz-enhanced photoacoustic spectroscopy based on a single-line spot pattern multi-pass cell
Authors: Cui Ruyue , Wu Hongpeng , Dong Lei , Chen Weidong , Tittel Frank K.
Published: April 2021

Multiple-sound-source-excitation quartz-enhanced photoacoustic spectroscopy (MSSE-QEPAS) based on a single-line spot pattern multi-pass cell (MPC) is reported for trace gas detection. The single-line spot pattern MPC is designed to make a laser beam pass through a quartz tuning fork (QTF) 60 times, thus producing 60 sound sources between the two QTF prongs. These sound sources excite the QTF operating at fundamental resonance mode in phase, resulting in a signal gain factor of ∼20. A theoretical mode based on convolution method is proposed to explain the working mechanism of MSSE-QEPAS.
Lie group solutions of advection-diffusion equations
Authors: Sun Yubiao , Jayaraman Amitesh S. , Chirikjian Gregory S.
Published: April 2021

Transport phenomena in homogeneous and inhomogeneous media are commonly encountered in many practical and industrial applications, which are modeled by advection-diffusion equations (ADEs) with constant or variable diffusivities, respectively. This paper provides a new perspective on how to solve advection-diffusion equations that model different transport phenomena in low Reynolds number flows. A mathematical description of the Lie group method is conducted first and then its potential in solving advection-diffusion equations for passive scalars transport with no-slip and no-flux boundary conditions is explored. The key step is to recast advection-diffusion equations as homogeneous diffusion processes on unimodular matrix Lie groups. Consequently, an approximate solution can be obtained from mean and covariance propagation techniques developed for diffusion equations on these Lie groups. The motivation to transform the advection-diffusion equation from Euclidean space to Lie groups is to exploit the available solutions of diffusion equation on these Lie groups so that the original equation can be solved in a simple way. In this paper, methodological details have been illustrated in solving ADEs modeling three kinds of transport phenomena. Two of them govern homogeneous transport and the solutions from mean and covariance propagation on the Lie group agree well with available results in published papers. We also use this method to solve more complicated ADEs governing inhomogeneous transport in one-dimensional compressible flows with spatially varying diffusivity, which is beyond the capabilities of existing approaches. The three real problems solved by the Lie group method illustrate the potential of this method. Instead of numerical calculations, the proposed closed-form method provides a simple alternative to study mass transfer encountered in various complex physical and industrial processes.
UV-induced change in channel conductivity in AlGaN/GaN high electron mobility transistors to measure doping
Authors: Wohlfahrt Markus , Uren Michael J. , Kaess Felix , Laboutin Oleg , Hirshy Hassan , Kuball Martin
Published: April 2021

AlGaN/GaN High Electron Mobility Transistors (HEMTs) frequently show an UV-induced increase in channel conductivity (persistent photoconductivity—PPC). PPC is a generic effect that exists for a wide range of HEMT configurations irrespective of the substrate material or the nominal buffer doping type and magnitude. Simulations demonstrate that the magnitude of the PPC effect can be explained by the UV-induced change in electronic band bending in the buffer below the 2D electron gas (2DEG). It only has a significant magnitude for p-type buffers that result from the presence of intentional or unintentional carbon doping and allows the net deep-level doping density (i.e., |NA-ND|) below the 2DEG to be quantified, a parameter that is extremely difficult to evaluate by any other means. Transient measurements indicate a PPC recovery time extending to several days, with leakage along dislocations playing an important role in this recovery.
Shortened tethering filaments stabilize presynaptic vesicles in support of elevated release probability during LTP in rat hippocampus
Authors: Jung Jae Hoon , Kirk Lyndsey M. , Bourne Jennifer N. , Harris Kristen M.
Published: April 2021

Significance

Long-term potentiation (LTP), a form of synaptic plasticity important for learning and memory, results in an increased probability of release of neurotransmitter from presynaptic vesicles. Prior work showed total vesicle number was decreased following LTP, seemingly inconsistent with this increased probability of release. Presynaptic vesicles are tethered to the active zone via filaments composed of molecules engaged in docking, priming, and release processes. Here, electron-microscopic tomography revealed a higher density of docked vesicles at active zones. Tethering filaments on vesicles at the active zone were shorter, and their attachment sites were shifted closer to the active zone. These changes suggest more vesicles were docked and primed, which would increase the probability of release 2 h after induction of LTP.
A conserved folding nucleus sculpts the free energy landscape of bacterial and archaeal orthologs from a divergent TIM barrel family
Authors: Jain Rohit , Muneeruddin Khaja , Anderson Jeremy , Harms Michael J. , Shaffer Scott A. , Matthews C. Robert
Published: April 2021

Significance

Orthologous proteins from the three superkingdoms have conserved their structures and functions over evolutionary time. We ask whether their folding mechanisms and the structures of their partially folded states are similarly conserved, using bacterial and archaeal representatives of the IGPS TIM barrel enzyme. Comparison of circular dichroism and fluorescence spectroscopic studies reveal a highly conserved mechanism, and hydrogen–deuterium exchange mass spectrometry analyses highlight similar cores of stability in regions dominated by clusters of branched aliphatic side chains. A bioinformatics analysis of hundreds of IGPS sequences from each superkingdom shows a very highly conserved sequence, V/ILLI, that nucleates the formation of a misfolded, microsecond intermediate and has existed since the last universal common ancestor of the IGPS family of proteins.
Life-course trajectories of body mass index from adolescence to old age: Racial and educational disparities
Authors: Yang Yang Claire , Walsh Christine E. , Johnson Moira P. , Belsky Daniel W. , Reason Max , Curran Patrick , Aiello Allison E. , Chanti-Ketterl Marianne , Harris Kathleen Mullan
Published: April 2021

Significance

This comprehensive life-course longitudinal study of body mass index (BMI) contributes knowledge about the temporal dynamics of BMI as individuals age and how social status defines disparities in lifetime obesity risk. Results show that adolescence and young adulthood are critical life stages when excess weight can rapidly accumulate and racial/ethnic or educational disparities emerge, most significantly among recent cohorts of young people. These cohort increases in the prevalence and rate of increase in obesity have alarming consequences for contemporary epidemiologic conditions such as the COVID-19 pandemic and US population health and life expectancy in years to come. Our study further contributes data analytic tools by linking and integrating multiple existing studies to advance science on social determinants of health.
An introgressed gene causes meiotic drive inNeurospora sitophila
Authors: Svedberg Jesper , Vogan Aaron A. , Rhoades Nicholas A. , Sarmarajeewa Dilini , Jacobson David J. , Lascoux Martin , Hammond Thomas M. , Johannesson Hanna
Published: April 2021

Significance

In order to survive, most organisms must deal with parasites. Such parasites can be other organisms or, sometimes, selfish genes found within the host genome itself. While much is known about parasitic organisms, the interaction with their hosts, and their ability to spread within and between species, much less is known about selfish genes. We here identify a selfish “spore killer” gene in the fungusNeurospora sitophila. The gene appears to have evolved within the genus but has entered the species through hybridization and introgression. We also show that the host can counteract the gene through RNA interference. These results shed light on the diversity of selfish genes in terms of origin, evolution, and host interactions.