bluuebunny/crossref_metadata_2025 huggingface dataset:
Intra-annual fluctuations dominating temporal dynamics of benthic diatom assemblages in a Chinese mountainous river
Authors: Guo Shuhan , He Fengzhi , Tang Tao , Tan Lu , Cai Qinghua
Published: August 2020

Understanding temporal dynamics of community may provide insights on biological responses under environmental changes. However, our knowledge on temporal dynamics of river organisms is still limited. In the present study, we employed a multivariate time-series modeling approach with a long-term dataset (i.e. 72 consecutive months) to investigate temporal dynamics of benthic diatom communities in four sites located in a Chinese mountainous river network. We hypothesized that: (1) there are multi-scale temporal dynamics within the diatom community; (2) intra-annual fluctuations dominate the community dynamics; (3) diatom species composing the community respond distinctly to environmental changes. We found that intra-annual fluctuations with periodicities <12 months explained 8.1–16.1% of community variation. In contrast, fluctuations with periodicities of 13–36 months and 37–72 months only accounted for 1.1–5.9% and 2.8–9.7% of variance in diatom community dynamics, respectively. Taxa correlating significantly to each significant RDA axis (namely, RDA taxa group) displayed distinct temporal dynamics. Conductivity, total nitrogen, and pH were important to most RDA taxa groups across the four sites while their effects were group-specific. We concluded that intra-annual dynamics dominated temporal variation in diatom communities due to community responses to local environmental fluctuations. We suggest that long-term monitoring data are valuable for identifying multiple-scale temporal dynamics within biological communities.
Contact modelling of highly heterogeneous friction material for braking applications
Authors: Arfa Essosnam , Magnier Vincent , Dufrénoy Philippe , de Saxcé Géry
Published: August 2020

Friction brakes are increasingly undergoing considerable development to improve their durability, efficiency, maintenance costs and environmental impact. Nevertheless, to achieve this, it is necessary to understand the different mechanisms involved in contact that are multi-scale and multi-physical in nature. On the multi-scale aspect, it is well known experimentally that heterogeneities have a pre-weighted role on performance without being able to explain it. Thus, modelling seems to be a good way to better understand the influence of these heterogeneities, provided that we have a multi-scale method to consider them. The objective of this article is therefore to propose a methodology for simulating contact in the presence of heterogeneous materials. The strategy consists in enriching the contact rigidity in terms of behaviour by a method of numerical homogenization. The significant advance of this article lies in the consideration of contact within the technique of numerical homogenization of a heterogeneous material. The strategy is then validated by comparing the mechanical fields between the proposed method and an explicitly meshed case. One of the main contributions of this work is the reduction in computing time compared to the traditional FEM method.
Identification of the pore size distribution of a porous medium by yield stress fluids using Herschel-Bulkley model
Authors: Oukhlef Aimad , Ambari Abdelhak , Champmartin Stéphane
Published: August 2020

In this paper, we present a new method to determine the pore-size distribution (PSD) in a porous medium. This innovative technique uses the rheological properties of non-Newtonian yield stress fluids flowing through the porous sample. In a first approach, the capillary bundle model will be used. The PSD is obtained from the measurement of the total flow rate of fluid as a function of the imposed pressure gradient magnitude. The mathematical processing of the experimental data, which depends on the type of yield stress fluid, provides an overview of the pore size distribution of the porous material. The technique proposed here was successfully tested analytically and numerically for usual pore size distributions such as the Gaussian mono and multimodal distributions. The study was conducted for yield stress fluids obeying the classical Bingham model and extended to the more realistic Herschel-Bulkley model. Unlike other complex methods, expensive and sometimes toxic, this technique presents a lower cost, requires simple measurements and is easy to interpret. This new method could become in the future an alternative, non-toxic and cheap method for the characterization of porous materials.
Contact pressure in misaligned spline couplings
Authors: Dupertuis Clément , Ligier Jean-Louis
Published: August 2020

Spline couplings are increasingly being studied because of their growing use, particularly in the field of electric cars. Due to clearances, geometrical obligations and elastic deformation, spline couplings operate mainly in slightly misaligned situations. From these kinds of situations, problems could appear such as vibrations or contact damages. The purpose of this article is to analyse the misalignment of splined couplings and the effects it induces. In order to identify behavioural trends, this work offers analytical approaches for estimating contact pressures in spline connections. In the chosen approach, the simplifying hypotheses necessary for equations are detailed as well as the various analytical modelling. Despites these assumptions, comparisons with pure numerical approaches illustrates the quality of analytical approach adopted in this paper. This method of modelling contact pressure allows the identification of the main mechanical factors to be identified including stiffness, thus deceasing problems due to misalignments.
Stillfortbildungen im Perinatalzentrum – ein systematischer Überblick
Authors: Tönnes Janina , Petersen-Ewert Corinna
Published: August 2020

Die Rate an Frühgeburten weltweit und in Deutschland ist seit Jahren gleichbleibend. Für diese Patientengruppe ist Muttermilch ein wertvolles Gut. Gleichzeitig ist der Stillbeginn für Mütter und ihre Frühgeborenen besonders schwer. Sie sind auf das kompetente Fachpersonal in der Klinik angewiesen. Häufig fühlt sich gerade das Fachpersonal aber nicht gut vorbereitet auf diese spezielle Aufgabe. Es braucht effektive Möglichkeiten der Fortbildung von Gesundheitsfachpersonal in Perinatalzentren, um den besonderen Herausforderungen der betroffenen Familien adäquat begegnen zu können.
Akupunktur und ihr Einfluss auf das Immunsystem – Hintergründe und Wirkungen beim landwirtschaftlichen Nutztier
Authors: Kuhlow Tim , Mohr Elmar
Published: August 2020

Im Rahmen der vorliegenden Literaturstudie wurden die aktuellen Kenntnisse über den Zusammenhang zwischen Akupunkturbehandlung und Reaktion des Immunsystems zusammengefasst. Die Akupunktur spricht über eine Kopplung von Nerven- und Immunsystem sowohl unspezifische angeborene als auch spezifische Abwehrmechanismen an. Diesbezüglich wurden 69 wissenschaftliche Studien herangezogen und ausgewertet. Die Ergebnisse lassen darauf schließen, dass über eine Stimulation peripherer Nervenbahnen an definierten Punkten eine Immunmodulation erfolgt. Primär wird dabei der angeborene unspezifische Teil des Immunsystems angesprochen. Einer der zu diesem Zweck häufig genannten Akupunkturpunkte ist Ma 36.
Forward and Retro Locomotion Training on Anthropometrical Body
Compositions and Aerobic Performance
Authors: Kachanathu Shaji John , Al-Kheraif Abdulaziz A. , Alenazi Aqeel M , Hafez Ashraf R , Nuhmani Shibili , Algarni Abdulrahman D
Published: August 2020

Background Forward and retro locomotion on a treadmill is a common tool
for lower extremity rehabilitation in the clinical setting. The purpose of this
study was to evaluate effect on anthropometrical body composition adaptations
and aerobic performance during forward and retro locomotion training on a
treadmill at 10-degree inclinations.

Methods A convenience sample of 30 healthy male subjects with mean age of
20.93±2.54 years, participated in the study. Subjects were divided into
2 groups, Forward Locomotion Group (FLG) and Retro Locomotion Group (RLG)
(n=15) and performed forward and retro locomotion training on a
treadmill at 10-degree inclination respectively for duration of 6 weeks. Study
outcomes such as aerobic performance and anthropometrical body composition were
measured at pre and post intervention phases.

Results Although both FLG and RLG training improved aerobic performance
significantly. However, RLG reported a significant improvement as compared to
FLG in the above parameters. Whereas, anthropometrical body composition changes
are not found to be significant even after 6 weeks of intervention in both
groups.

Conclusion Both the forward and retro locomotion training improved
aerobic performance but not the body composition variables, also retro
locomotion training was more effective than forward locomotion in improving
aerobic performance.
The Prevalence of Joint Hypermobility among High School and University Students
Authors: Kashif Muhammad , Albalwi Abdulaziz Aoudh , Fatima Nisar , Fatima Nasreen
Published: August 2020

Background Joint hypermobility (JH) prevails worldwide, especially in
children and females, although its consequences have been neglected and
understated by health care practitioners. JH can lead to musculoskeletal
injuries, which can have serious negative effects on a person’s health.
This topic has not been sufficiently studied in Pakistan so this study will help
in filling the gap.

Objective This study aims to determine the prevalence of asymptomatic
joint hypermobility, among high school and university students, at 2
institutions in Pakistan.

Methodology A total of 1,749 students, with an average age of 16.96
(range 14–26), who studied at Dar e Arqam School or Riphah International
University in Faisalabad were examined. The Beighton criteria system was used to
determine the prevalence of JH on the basis of minor criteria for hypermobility
(1/9–3/9 joints, indicating localized and peripheral
hypermobility) and major criteria (4/9 joints or above 4 joints,
indicating generalized hypermobility).

Results The results showed that the prevalence of JH in female students
studying in high school was 61.9%, and in female university students,
the prevalence was 58.4%. Minor hypermobility was most common among
university students in their 5th to 8th semester (60.3%), while major
hypermobility occurred most frequently in high school students of 9th grade
(80.1%). In addition, the results of the study established that joint
hypermobility was most common in the elbow joint on the right side: 673
(94.7%) male and 1,002 (96.5%) female students.

Conclusion The prevalence of common hypermobility, especially generalized
hypermobility, was high among female high school students compared to university
students, and hypermobility in the right trunk and elbow joint was more common
compared to other joints.
Embedding Heteroatoms and Adjacent Pentagons in Concave Molecules
Authors: Zhang Gang
Published: August 2020

Bowl-shaped molecules, which can be viewed as fragments of fullerenes, have been extensively studied owing to their interesting fundamental properties derived from their unique geometry, and the possibilities for their further functionalization, with potential applications in the field of materials science. Most of the reported concave compounds are based on corannulene or sumanene, the simplest representative fullerene subunits possessing isolated pentagons. Syntheses of concave molecules bearing adjacent pentagons have rarely been reported. Inspired by the structure of N-heterotriangulene, the construction of bowl-shaped compounds containing two fused pentagons and a central nitrogen atom is discussed. Further surface extension of such concave molecules can result in the formation of boat-shaped compounds containing embedded double isolated nitrogen atoms.
Ocular Sarcoidosis
Authors: Sève Pascal , Jamilloux Yvan , Tilikete Caroline , Gerfaud-Valentin Mathieu , Kodjikian Laurent , El Jammal Thomas
Published: August 2020

Sarcoidosis is one of the leading causes of inflammatory eye disease. Any part of the eye and its adnexal tissues can be involved. Uveitis and optic neuropathy are the main manifestations, which may require systemic treatment. Two groups of patients with sarcoid uveitis can be distinguished: one of either sex and any ethnicity in which ophthalmological findings are various and another group of elderly Caucasian women with mostly chronic posterior uveitis. Clinically isolated uveitis revealing sarcoidosis remains a strictly ocular condition in a large majority of cases. Although it can be a serious condition involving functional prognosis, early recognition in addition to a growing therapeutic arsenal (including intravitreal implant) has improved the visual prognosis of the disease in recent years. Systemic corticosteroids are indicated when uveitis does not respond to topical corticosteroids or when there is bilateral posterior involvement, especially macular edema. In up to 30% of the cases that require an unacceptable dosage of corticosteroids to maintain remission, additional immunosuppression is used, especially methotrexate. As with other forms of severe noninfectious uveitis, monoclonal antibodies against tumor necrosis factor-α have been used. However, only very rarely does sarcoid uveitis fail to respond to combined corticosteroids and methotrexate therapy, a situation that should suggest either poor adherence or another granulomatous disease. Optic neuropathy often affects women of African and Caribbean origins. Some authors recommend that patients should be treated with high-dose of corticosteroids and concurrent immunosuppression from the onset of this manifestation, which is associated with a poorer outcome.
History of Chronic Traumatic Encephalopathy
Authors: Cantu Robert C. , Bernick Charles
Published: August 2020

The long-term effects of repetitive head impacts have been recognized for close to a century. What is now referred to as chronic traumatic encephalopathy (CTE) was first described by Martland in 1928 in a series of boxers. Over the years, several important articles were published, including Critchley's 1957 report where he introduced the term “chronic traumatic encephalopathy,” Robert's study in 1969 which provided evidence of the prevalence of neurological impairment in retired fighters, and Corsellis' initial description of the pathology of CTE. However, what brought public attention to the issue of CTE in sports were the postmortem findings of CTE pathology in professional American football players, initially reported by Omalu and subsequently in a large series by McKee. There is now standardization of pathological criteria for CTE and recognition that it can be seen across all activities that involve repetitive head impacts.
Management of a Difficult Airway Scenario in a Case of Hurler’s Syndrome with a D-Blade Video Laryngoscope
Authors: Thakkar Keta D. , Hrishi Ajay P. , Sethuraman Manikandan , Vimala Smita
Published: August 2020

Hurler’s syndrome is a rare genetic disease characterized by progressive multiorgan accumulation of glycosaminoglycans. It is associated with progressive craniofacial, skeletal, and cardiac involvement, which increases the risk of anesthesia. Patients with Hurler’s syndrome could present as the worst airway management problem an anesthesiologist could deal with due to abnormal upper airway anatomy and limited neck manipulation, owing to the atlantoaxial instability. We report a case of difficult airway scenario of a child with Hurler’s syndrome, leading to an apparent cannot ventilate cannot intubate scenario, which was managed successfully with the help of a C-MAC video laryngoscope with unique D-blade. In Hurler’s syndrome, C-MAC with D-blade is an excellent tool in establishing an airway in a pediatric difficult airway scenario. Moreover, D-blade C-MAC could be considered as the primary tool for establishing an airway in pediatric patients with Hurler’s syndrome.
Effects of Fenoldopam in the Pediatric Population: Fluid Status, Serum Biomarkers, and Hemodynamics: A Systematic Review and Meta-Analysis
Authors: Villarreal Enrique G. , Rausa Jacqueline , Chapel A Claire , Loomba Rohit S. , Flores Saul
Published: August 2020

Fluid overload is a frequent complication in children during critical illness. Fluid restriction and diuretic agents have been the mainstay therapies so far. Fenoldopam, a selective dopamine-1 receptor agonist, is a diuretic agent with promising effects in the pediatric population. The purpose of this meta-analysis is to evaluate the outcomes of pediatric patients who received fenoldopam. We hypothesized that the administration of fenoldopam will cause an increase in urine output and decrease in serum creatinine in this patient population. A comprehensive database search of PubMed, EMBASE, and Cochrane libraries from the databases' inception through December 2018 was undertaken. Independent reviewers selected appropriate studies and the reviewed data. A meta-analysis was then conducted to determine the effects of fenoldopam on hemodynamics, the amount of vasoactive support, and renal function in children under the critical care setting. The selected end points were measured prior to the administration of fenoldopam and 24 hours after the initiation of the infusion: urine output, serum creatinine, serum sodium, inotrope score, heart rate, central venous pressure, systolic blood pressure, and mean blood pressure. Forest plots were generated to demonstrate individual study data as well as pooled data for each end point. A total of five studies (three retrospective cohort studies, two randomized trials) with 121 patients were included for analysis. No significant difference was observed in urine output, inotrope score, systolic blood pressure, or mean blood pressure. There was a statistically significant increase in serum creatinine and central venous pressure. There was statistically significant decrease in serum sodium and heart rate, and central venous pressure. This meta-analysis did not identify significant renoprotective or vasodilator effects from fenoldopam in this patient population. Although mild electrolyte and hemodynamic changes were identified, larger studies are warranted to determine the clinical significance of fenoldopam in this patient population.
A Comparative Clinical Study between Concentrated Growth Factor and Low-Level Laser Therapy in the Management of Dry Socket
Authors: Kamal Aqsa , Salman Basheer , Razak Noor Hayatie Abdul , Samsudin AB Rani
Published: August 2020

Objective A dry socket is a well-recognized complication of wound healing following tooth extraction. Its etiology is poorly understood and commonly occur among healthy patients. As such, management strategies for dry socket has always been empirical rather than scientific with varying outcome. The aim of this study is to investigate the efficacy of concentrated growth factor (CGF) and low-level laser therapy (LLLT) and compared them to the conventional treatment in the management of dry socket.

Materials and Methods Sixty patients with one dry socket each, at University Dental Hospital Sharjah, were divided into three treatment groups based on their choice. In group I (n = 30), conventional treatment comprising of gentle socket curettage and saline irrigation was done. Group II (n = 15) dry sockets were treated with CGF and group III (n = 15) sockets were lased with LLLT. All dry socket patients were seen at day 0 for treatment and subsequently followed-up at 4, 7, 14, and 21 days. Pain score, perisocket inflammation, perisocket tenderness, and amount of granulation tissue formation were noted.

Statistical Analysis Data were analyzed as mean values for each treatment group. Comparisons were made for statistical analysis within the group and among the three groups to rank the efficacy of treatment using one-way analysis of variance (ANOVA). Statistically significant difference is kept at p < 0.05.

Results  Conventional treatment group I took more than 7 days to match the healing phase of group II CGF treated socket and group III LLLT irradiated socket (p = 0.001). When healing rate between CGF and LLLT are compared, LLLT group III showed a delay of 4 days compared with CGF in granulation tissue formation and pain control.

Conclusion  CGF treated socket was superior to LLLT in its ability to generate 75% granulation tissue and eliminate pain symptom by day 7 (p = 0.001).
Time windows of opportunities to fight earthquake under-insurance: evidence from Google Trends
Authors: Gizzi Fabrizio Terenzio , Kam Jonghun , Porrini Donatella
Published: August 2020

Earthquake insurance can be a useful tool to build more sustainable societies and disaster-resilient communities. However, the coverage is not common in many countries. This article aims to contribute to the literature through an empirical analysis of the online interest in earthquake insurance through Google Trends. The proposed methodology implies to move from a top-down conceptual approach to a bottom-up/data-enabled one. It allows us to explore potential triggers and dynamic patterns of online interest in earthquake insurance at daily time-scale through the lens of Big Data. In order to validate the methodology, the article considers Italy as a test area. For this country, where the coverage rate is low, we fuse multiple databases to create 16-year daily time series of public search activities about the insurance in Italy and analyse it with other data sources. As a result, the peak analysis shows a connection with the occurrences of large domestic earthquakes, overseas earthquakes, and policy decisions, which create time windows of opportunities for insurers and policymakers to boost the public’s motivation towards the coverages. The research outcomes suggest that the data-enabled approach can additionally be applied in other countries where the coverage rate is low and stakeholders are facing the challenge to strive against earthquake under-insurance.
Comparing global and local control of cardiac alternans
Authors: Patrick Chris
Published: August 2020

Numerical modeling of human ventricular tissue demonstrates constant TR pacing better prevents alternans than constant DI pacing.
Discharge parameters of PlasmaKristall-4BU: A modifiable dusty plasma experiment
Authors: Schmidt J. , Hyde T. W.
Published: August 2020

The Plasmakristall-4 (PK-4) experiment is used for experiments under microgravity conditions with dusty plasmas on the International Space Station. The experiment PK-4BU is based on a similar experimental concept but offers the possibility of modifications to the device to gain crucial information on the influence of several parameters on the experiment. Within this work, electrostatic probe and spectroscopy measurements have been taken within the PK-4BU experiment to determine electron temperature Te, electron density ne, and plasma potential φ as well as to gain information about the composition of the background gas. It has been found that the discharge parameters are similar to results from comparable devices, while a small influence of impurities within the working gas cannot be neglected.
Global vs local control of cardiac alternans in a 1D numerical model of human ventricular tissue
Authors: Thakare Sanket , Mathew Joseph , Zlochiver Sharon , Zhao Xiaopeng , Tolkacheva Elena G.
Published: August 2020

Cardiac alternans is a proarrhythmic state in which the action potential duration (APD) of cardiac myocytes alternate between long and short values and often occurs under conditions of rapid pacing of cardiac tissue. In the ventricles, alternans is especially dangerous due to the life-threatening risk of developing arrhythmias, such as ventricular fibrillation. Alternans can be formed in periodically paced tissue as a result of pacing itself. Recently, it has been demonstrated that this pacing-induced alternans can be prevented by performing constant diastolic interval (DI) pacing, in which DI is independent of APD. However, constant DI pacing is difficult to implement in experimental settings since it requires the real-time measurement of APD. A more practical way was proposed based on electrocardiograms (ECGs), which give an indirect measure of the global DI relaxation period through the TR interval assessment. Previously, we demonstrated that constant TR pacing prevented alternans formation in isolated Langendorff-perfused rabbit hearts. However, the efficacy of “local” constant DI pacing vs “global” constant TR pacing in preventing alternans formation has never been investigated. Thus, the purpose of this study was to implement an ECG-based constant TR pacing in a 1D numerical model of human ventricular tissue and to compare the dynamical behavior of cardiac tissue with that resulted from a constant DI pacing. The results showed that both constant TR and constant DI pacing prevented the onset of alternans until lower basic cycle length when compared to periodic pacing. For longer cable lengths, constant TR pacing was shown to exhibit greater control on alternans than constant DI pacing.
Bactericidal efficacy of nanopatterned surface tuned by topography
Authors: Xiao Ke , Cao Xuezheng , Chen Xi , Hu Hanzi , Wu Chenxu
Published: August 2020

Due to the exciting physical mechano-bactericidal approach developed in recent years using nanopatterned surfaces with its potential applications in biomedical engineering, now it becomes crucially important to fabricate optimal surface structures so as to achieve the best bactericidal ability. In this paper, the bactericidal efficacy of the cylindrical nanopillar-patterned surface and the sinusoidal nanopillar-patterned surface is presented via minimizing total free energy for a bacterial cell adhered on these two kinds of surfaces. Our theoretical analyses show that the adhesion depth at equilibrium along the nanopillar shafts and the corresponding stretching degree is related to the the nanopillar density and nanopillar radius. The bactericidal efficacy on the nanopillar-patterned surface is determined by the combination of nanopillar density and naopillar radius, which is also supported by the phase diagrams obtained, showing that at large internanopillar spacing and nanopillar radius, the sinusoidal nanopillar-patterned surface is more advantageous in bactericidal efficacy, while in small interspacing and nanopillar radius, the cylindrical nanopillar-patterned surface structure is more powerful. The conclusions obtained in this paper unveil how the mechano-bactericidal effect is achieved by tuning the topography of the nanopatterned surface, a technique helpful to the optimal design and fabrication of bio-mimicking nanotextured surfaces.
Dynamically reconfigurable magnonic crystal composed of artificial magnetic skyrmion lattice
Authors: Wang Xi-guang , Nie Yao-Zhuang , Xia Qing-lin , Guo Guang-hua
Published: August 2020

Skyrmion-based magnonic crystal (MC) provides the dynamic tunability of manipulating magnonic band structure, and this brings obvious advantages over geometry or material-modulated MCs with a static band. But the existence of stable skyrmion usually requires strong Dzyaloshinskii–Moriya interaction (DMI) in combination with an external magnetic field under specific strength, and all these features limit the experimental realization and practical designing of the skyrmion-based MC. Here, we introduce the concept of artificial magnetic skyrmion-based MC. The artificial skyrmion lattice is realized by patterning an array of magnetic nanodisks on a thin film. The coupling between nanodisks and thin film generates an array of skyrmions possessing the same period as the nanodisk array. Via applying the pulsed magnetic field, one can turn on and off the skyrmion lattice, which allows switching between two very different magnonic band structures. Furthermore, via a honeycomb lattice, we extend this design to the dynamic on and off for chiral magnon edge state. The on and off switching is fast and in the range of nanoseconds. Considering that the coupling from nanodisks can greatly enhance the stability of skyrmions, no matter whether the DMI or magnetic field exists or not, our design points to a simple realization of dynamic skyrmion MC and topological magnonic devices.
Mechanism of pressure induced amorphization of SnI4: A combined x-ray diffraction—x-ray absorption spectroscopy study
Authors: Fonda Emiliano , Polian Alain , Shinmei Toru , Irifune Tetsuo , Itié Jean-Paul
Published: August 2020

We have studied the amorphization process of SnI4 up to 26.8 GPa with unprecedented experimental details by combining Sn and I K-edge x-ray absorption spectroscopy and powder x-ray diffraction. Standard and reverse Monte Carlo extended x-ray absorption fine structure (EXAFS) refinements confirm that the penta atomic SnI4 structural unit tetrahedron is a fundamental structural unit that appears preserved through the crystalline phase-I to crystalline phase-II transition that has been previously reported between 7 GPa and 10 GPa. Up to now, unexploited iodine EXAFS reveals to be extremely informative and confirms the progressive formation of iodine–iodine short bonds close to 2.85 Å. A coordination number increase of Sn in the crystalline phase-II region appears to be excluded, while the deformation of the tetrahedral units proceeds through a flattening that keeps the average I–Sn–I angle close to 109.5°. Moreover, we put in evidence the impact of pressure on the Sn near edge structure under competing geometrical and electronic effects.
Quantification of the As/P content in GaAsP during MOVPE growth
Authors: Supplie Oliver , Heinisch Alexander , Paszuk Agnieszka , Nandy Manali , Tummalieh Ammar , Kleinschmidt Peter , Sugiyama Masakazu , Hannappel Thomas
Published: August 2020

Epitaxial integration of direct-bandgap III–V compound semiconductors with silicon requires overcoming a significant lattice mismatch. To this end, GaAsP step-graded buffer layers are commonly applied. The thickness and composition of the individual layers are decisive for the envisaged strain relaxation. We study GaAsP growth by metalorganic vapor phase epitaxy in situ with reflection anisotropy spectroscopy. We find that the growth surface exhibits optical fingerprints of atomically well-ordered surfaces. These allow for tuning the interface preparation between adjacent layers. The spectral position of the characteristic peaks in the RA spectra, which are related to surface-modified bulk transitions, behaves similarly upon an increased As content as does the E1 interband transition of GaAsP at the growth temperature. The impact of strain on this shift is negligible. We thus monitor a bulk property via the surface reconstruction. An empiric model enables quantification of the As content of individual layers directly in situ without growth interruptions and for various surface reconstructions. Our findings are suitable for a simplified optimization of the GaAsP buffer growth for high-efficiency devices.
The OpenKIM processing pipeline: A cloud-based automatic material property computation engine
Authors: Karls D. S. , Bierbaum M. , Alemi A. A. , Elliott R. S. , Sethna J. P. , Tadmor E. B.
Published: August 2020

The Open Knowledgebase of Interatomic Models (OpenKIM) is a framework intended to facilitate access to standardized implementations of interatomic models for molecular simulations along with computational protocols to evaluate them. These protocols include tests to compute material properties predicted by models and verification checks to assess their coding integrity. While housing this content in a unified, publicly available environment constitutes a major step forward for the molecular modeling community, it further presents the opportunity to understand the range of validity of interatomic models and their suitability for specific target applications. To this end, OpenKIM includes a computational pipeline that runs tests and verification checks using all available interatomic models contained within the OpenKIM Repository at https://openkim.org. The OpenKIM Processing Pipeline is built on a set of Docker images hosted on distributed, heterogeneous hardware and utilizes open-source software to automatically run test–model and verification check–model pairs and resolve dependencies between them. The design philosophy and implementation choices made in the development of the pipeline are discussed as well as an example of its application to interatomic model selection.
Photofield electron emission from an optical fiber nanotip
Authors: Keramati S. , Passian A. , Khullar V. , Batelaan H.
Published: August 2020

We demonstrate a nanotip electron source based on a graded index multimode silica optical fiber, tapered at one end to a radius of curvature r ∼50 nm and coated with a thin film of gold. We report observation of laser-induced electron photoemission at tip bias potentials below the onset of dark field emission. Single-photon photofield emission is identified as the emission mechanism that exhibits fast switching times with an upper limit on the order of 1 μs. The explored fiber optic nanotips are flexible back-illuminated emitters, which can be operated in continuous wave and pulsed modes using lasers with photon energies in the visible range or higher. The mechanical flexibility of the source can facilitate externally controlled positioning. Multiple, individually addressable, nanotips may be assembled into a bundle for applications such as computational electron ghost imaging.
Quantum size effect in nanocorrals: From fundamental to potential applications
Authors: Li Qili , Cao Rongxing , Ding Haifeng
Published: August 2020

Conventional silicon-based devices are approaching the scaling limits toward super miniaturization, where the quantum size effect naturally emerges with increasing importance. Exploring the quantum size effect may provide additional functionality and alternative architectures for information processing and computation. Scanning tunneling microscopy/spectroscopy is an ideal tool to explore such an opportunity as it can construct the devices in an atom-by-atom fashion and investigate their morphologies and properties down to the atomic level. Utilizing nanocorrals as examples, the quantum size effect is demonstrated to possess the great capability in guiding the adatom diffusion and the self-assembly, controlling the statistical fluctuation, tuning the Kondo temperature, etc. Besides these fundamentals, it also shows strong potential in logic operations as the basic logic gates are constructed.
Heuristics for chemical species identification in dense systems
Authors: Rice Betsy M. , Mattson William D. , Larentzos James P. , Byrd Edward F. C.
Published: August 2020

A new approach to identify chemical species from molecular dynamics (MD) simulations of reacting materials under extreme temperatures and pressures is presented. The approach is based on bond-distance and vibrational criteria, derived from the examination of atomic behavior during a density functional theory MD simulation of an overdriven shock of the explosive pentaerythritol tetranitrate. For comparison, the trajectory was analyzed using popular bonding criteria commonly used in analysis of reactive MD simulations, including distance, distance–time, and bond-order criteria. Cluster analyses using the new time-dependent bond definition approach presented here and a bond-order approach revealed that species and their corresponding lifetimes were strongly dependent on the chosen approach, indicating significant implications for the development of chemical mechanisms and chemical kinetics models using the results of reactive MD simulations.
Experimental study on free-surface deformation and forces on a finite submerged plate induced by a solitary wave
Authors: Wang Qian , Liu Hua , Fang Yongliu , Dias Frederic
Published: August 2020

Physical experiments are conducted to study the interaction between a solitary wave and a finite horizontal plate submerged at a depth equal to 1/4 of the water depth. The spatial and temporal variation of the three-dimensional (3D) surface deformation is measured using a multi-lens stereo reconstruction system. The hydrodynamic loads are measured by underwater load cells. The plate-induced shoaling causes 3D wave focusing, leading to an increased maximum elevation along the streamwise centerline of the plate. The detailed wave focusing process and the influence of wave amplitude on focusing are presented based on the results obtained through image processing. The characteristics of the horizontal forces, vertical forces, and pitching moments are discussed. A 6-stage loading process based on the maxima of vertical wave force and pitching moment is proposed. It is coupled with the synchronous surface deformation to reveal the loading mechanism. It proves that the vertical wave force on the plate reduces apparently compared with the results from 2D experiments. The surface elevation and wave-induced load data provide an excellent benchmark for further studies on the 3D nonlinear interaction between a solitary wave and a submerged plate.
Accurate description of molecular dipole surface with charge flux implemented for molecular mechanics
Authors: Yang Xudong , Liu Chengwen , Walker Brandon D. , Ren Pengyu
Published: August 2020

The molecular dipole moment is strongly coupled to molecular geometry among different phases, conformational states, intermolecular interaction energy, and vibrational spectroscopy. Our previous inclusion of geometry dependent charge flux into the atomic multipole-based polarizable AMOEBA+ force field has shown significant improvement of water properties from gaseous to condensed phases [C. Liu et al., J. Phys. Chem. Lett. 11(2), 419–426 (2020)]. In this work, the parameterization of the CF model for a broad range of organic and biomolecular fragments is presented. Atom types are automatically assigned by matching the predefined SMARTS patterns. Comparing to the current AMOEBA+ model without the CF component, it is shown that the AMOEBA+ (CF) model improves the description of molecular dipole moments for the molecules we studied over both equilibrium and distorted geometries. For the equilibrium-geometry structures, AMOEBA+ (CF) reduces the mean square error (MSE) from 6.806 × 10−1 (without CF) to 4.249 × 10−4 D2. For non-equilibrium structures, the MSE is reduced from 5.766 × 10−1 (without CF) to 2.237 × 10−3 D2. Finally, the transferability of the CF model and parameters were validated on two sets of molecules: one includes molecules in the training set but with different geometries, and the other one involves new molecules outside of the training set. A similar improvement on dipole surfaces was obtained on the validation sets. The CF algorithms and parameters derived in this work are general and can be implemented into any existing molecular mechanical force fields.
Conformation of a single polyelectrolyte in poor solvents
Authors: Duan Chao , Li Weihua , Wang Rui
Published: August 2020

Understanding the conformation of a polyelectrolyte (PE) is not only a fundamental challenge in polymer science but also critical for understanding the folding and aggregation of proteins. Here, we develop a theory by systematically including the electrostatic interactions into the self-consistent field theory for polymers to study the conformational behaviors of a single PE in poor solvents. As the backbone charge fraction of the PE increases, our theory predicts that the spherical globule (Sph) can either be elongated to a series of pearl-necklace (PN) structures or be flattened to two novel structures that have not been reported before: biconcave red cell and toroid. While the PN structures are stable conformations, the two fattened structures are metastable. We find that the cylindrical globule, the stability of which is under debate, is an unstable structure. The signature of the PN structures obtained by our calculation is less pronounced than that reported by other theoretical works due to the continuous change in the curvature from the pearl to the necklace, which, however, is in good agreement with the results from molecular simulations and neutron scattering experiments. In addition, our theory reveals different characteristics of the globule to PN transition: the transition from the Sph to the PN with double pearls is discontinuous, whereas those from adjacent PN structures are continuous at finite salt concentrations. Furthermore, we observe different scaling behaviors: the string width is not a constant as a thermal blob but decays as the backbone charge fraction increases.
How good are polarizable and flexible models for water: Insights from a many-body perspective
Authors: Lambros Eleftherios , Paesani Francesco
Published: August 2020

We present a systematic analysis of state-of-the-art polarizable and flexible water models from a many-body perspective, with a specific focus on their ability to represent the Born–Oppenheimer potential energy surface of water from the gas to the liquid phase. Using coupled cluster data in the completed basis set limit as a reference, we examine the accuracy of the polarizable models in reproducing individual many-body contributions to interaction energies and harmonic frequencies of water clusters and compare their performance with that of MB-pol, an explicit many-body model that has been shown to correctly predict the properties of water across the entire phase diagram. Based on these comparisons, we use MB-pol as a reference to analyze the ability of the polarizable models to reproduce the energy landscape of liquid water under ambient conditions. We find that, while correctly reproducing the energetics of minimum-energy structures, the polarizable models examined in this study suffer from inadequate representations of many-body effects for distorted configurations. To investigate the role played by geometry-dependent representations of 1-body charge distributions in reproducing coupled cluster data for both interaction and many-body energies, we introduce a simplified version of MB-pol that adopts fixed atomic charges and demonstrate that the new model retains the same accuracy as the original MB-pol model. Based on the analyses presented in this study, we believe that future developments of both polarizable and explicit many-body models should continue in parallel and would benefit from synergistic efforts aimed at integrating the best aspects of the two theoretical/computational frameworks.
Deposition of carbon-containing hole injection layers on p-type Al0.8Ga0.2N grown by metalorganic vapor phase epitaxy
Authors: Kishimoto Katsuhiro , Funato Mitsuru , Kawakami Yoichi
Published: August 2020

A carbon-containing amorphous film is deposited on metalorganic-vapor-phase-epitaxy-grown AlN or AlGaN templates by flowing propane, aluminum, and nitrogen gases at 1010 °C. The deposited ∼1-nm-thick layers show p-type conductivity with a sheet carrier density of ∼1 × 1013 cm−2. When the film is deposited on Mg-doped Al0.8Ga0.2N prior to metallization, it acts as a hole injection layer into p-type AlGaN and shows nearly a double increase in hole current. The transmittance of the deposited layer is ∼90% in the 200–400-nm wavelength range. Hence, the deposited layer is a promising hole injection layer into high-Al-content p-type AlGaN.
A twist in the road less traveled: The AMBER ff15ipq-m force field for protein mimetics
Authors: Bogetti Anthony T. , Piston Hannah E. , Leung Jeremy M. G. , Cabalteja Chino C. , Yang Darian T. , DeGrave Alex J. , Debiec Karl T. , Cerutti David S. , Case David A. , Horne W. Seth , Chong Lillian T.
Published: August 2020

We present a new force field, AMBER ff15ipq-m, for simulations of protein mimetics in applications from therapeutics to biomaterials. This force field is an expansion of the AMBER ff15ipq force field that was developed for canonical proteins and enables the modeling of four classes of artificial backbone units that are commonly used alongside natural α residues in blended or “heterogeneous” backbones: chirality-reversed D-α-residues, the Cα-methylated α-residue Aib, homologated β-residues (β3) bearing proteinogenic side chains, and two cyclic β residues (βcyc; APC and ACPC). The ff15ipq-m force field includes 472 unique atomic charges and 148 unique torsion terms. Consistent with the AMBER IPolQ lineage of force fields, the charges were derived using the Implicitly Polarized Charge (IPolQ) scheme in the presence of explicit solvent. To our knowledge, no general force field reported to date models the combination of artificial building blocks examined here. In addition, we have derived Karplus coefficients for the calculation of backbone amide J-coupling constants for β3Ala and ACPC β residues. The AMBER ff15ipq-m force field reproduces experimentally observed J-coupling constants in simple tetrapeptides and maintains the expected conformational propensities in reported structures of proteins/peptides containing the artificial building blocks of interest—all on the μs timescale. These encouraging results demonstrate the power and robustness of the IPolQ lineage of force fields in modeling the structure and dynamics of natural proteins as well as mimetics with protein-inspired artificial backbones in atomic detail.
The population status of southern hairy-nosed wombats (Lasiorhinus latifrons). I. Distribution and abundance
Authors: Swinbourne Michael , Taggart David , Ostendorf Bertram
Published: August 2020

There is disagreement within the community regarding whether the distribution and abundance of southern hairy-nosed wombats (Lasiorhinus latifrons) is increasing or decreasing. On one hand, farmers and graziers within areas where wombats can be found have consistently claimed that wombat numbers have increased in recent decades. Conversely, conservation groups, including the International Union for the Conservation of Nature (IUCN), claim that the wombat population is experiencing a species-wide decline, and recently upgraded its conservation status to ‘Near Threatened’. To resolve this disparity, we used a combination of field surveys and the analysis of satellite imagery to map the species-wide distribution and to estimate the overall population abundance of southern hairy-nosed wombats. We found that the wombat population has grown substantially since the last major surveys in the 1980s; however, the growth has not been uniform. While the population group in the Gawler Ranges has experienced marked population growth, there has been only relatively modest growth in the Murraylands. On the Yorke Peninsula, while the overall population numbers do not appear to have changed, some colonies have disappeared entirely. We also found a substantial population of wombats in Western Australia that had not been previously reported.
Discourse (re)-framing
Authors: Kroo Judit
Published: August 2020

Focusing on the move from gakusei ‘student’ to shakaijin ‘working adult, lit.
fully socialized adult’ during a period of continuing economic stagnation and social dislocation, the current study analyzes
contemporary Japanese university students’ alignments with respect to ideologies surrounding adulthood including entering the job
market and marriage. Data includes naturally occurring conversations with male and female students at a mid-high ranked city
university on the outskirts of Yokohama as well as media materials associated with job-hunting practices. Analyzing individuals’
discursive (re)-framing of economic practice, this study demonstrates how individuals convey complex
alignments towards future economic and social practices and their attendant ideologies. These complex alignments are analyzed as
instances of ‘making do’ (de Certeau, 1984). Attending to subtle shifts in
discursive (re)-framing, this paper demonstrates how micropolitical alignments are enacted in language at the
level of everyday, ordinary practice.