bluuebunny/crossref_metadata_2025 huggingface dataset:
Challenges of cross-cultural communications in the era of the COVID-19 pandemic
Authors: Aksenova Anna Alekseevna , Andreeva Ekaterina Yurievna , Lugovaya Anastasiya Andreevna , Tikhonova Nataliya Yurievna
Published: December 2021

This article examines questions of the present interest in the sphere of modern education, the key topic of which is cross-cultural online communication of students in the context of the COVID-19 pandemic and complete shift to the distant format of work. The article analyzes the features of virtual communication between representatives of different cultures and languages, as well as examples of possible misunderstandings of certain cultural realities. The issue of effective communication and socialization of students in the online environment is debatable and relevant to study, which is proved by numerous studies derived from real interactions with foreign students during the period of necessary self-isolation due to the threat of coronavirus. The investigation is based on a questionnaire suggested to students and Internet discourse materials presented on websites and forums. The theoretical basis is a deep analysis of the articles of scientists who decided to delve into the linguistic aspect dictated by the need to study the phenomenon of communication during the pandemic. The task of this research is to analyze cases and Internet communication based on the conducted survey and data comparison. The article will provide views on the mentioned above matter supported by investigations of respected scientists with various illustrations from modern realities of the pandemic world.
Development of intercultural communicative competence in Russian-Chinese discourse
Authors: Kuprina Tamara Vladimirovna , Ming Mu , Evtyugina Alla Aleksandrovna , Shokhov Konstantin Olegovich
Published: December 2021

The expansion of intercultural interaction between countries and cultures requires the training of modern specialists who know both foreign languages and intercultural communication. However, in the training of translators, there is a lack of authentic material offered by the native speakers of the corresponding language and culture. The purpose of the article is to suggest strategies for teaching the translation of advertising texts and anthroponyms in the Russian-Chinese discourse. The methodological basis of the research is the theory of skopos considering translation as a practical type of activity, as well as a comparative analysis of anthroponyms. As a result of the research, there proposed strategies for translating advertising texts (working with linguistic forms, cultural content, adding and omitting information, combining these strategies) and anthroponyms (using transliteration from Russian into Chinese, it is necessary not only to choose suitable Chinese hieroglyphs but also take into account their meanings, special cases). Comparing Russian and Chinese names, an important difference is found: transliterating Russian names, a person’s gender information can be expressed through Chinese hieroglyphs but this effect cannot be achieved when transliterating Chinese names. Russian-Chinese discourse has a strong cultural connotation, reflecting the unique way of people’s life. The task of the translator is to reproduce not only the formal but also the cultural information of the original text. The novelty of the work is determined by the need to research the Sino-Tibetan language group in order to improve the methodology of teaching translation and intercultural communication as a practical activity.
Cognitive styles in methodology of Russian as a foreign language
Authors: Avdeyeva Irina Borisovna , Krasnokutskaya Nadezhda Vladimirovna
Published: December 2021

This article attempts to consider the types of cognitive activity of students in the process of learning foreign languages, including Russian as a foreign language. It contains a synthesis on this topic and practical results of the material implementation developed with the consideration of linguo-cognitive styles of students. Special attention is paid to the analytical cognitive style that is inherent in the students of technical fields. Considering the features of the linguo-cognitive picture of students with a predominantly analytical cognitive style, the authors conclude that these features are innate to the students from European countries who speak European languages and studied within the European educational system. Attention is paid to the consideration of cognitive styles in the existing training materials on RFL. The textbook, created by a group of authors (editor-in-chief Avdeyeva), which is addressed to students of the engineering field, was given as an example. Moreover, the article analyses the special course by Krasnokutskaya, developed at the Pushkin State Russian Language Institute and addressed to European students studying Russian as a foreign language. Based on the analysis and testing of mentioned training materials, conclusions on the feasibility of further development of such manuals are drawn.
Pandemic challenges for educators: transition from physical to digital classroom
Authors: Agaltsova Darya Vladislavovna , Milyaeva Larisa Vyacheslavovna
Published: December 2021

The article looks into some challenges that university teaching staff has to face during the modern era of digitalization and especially during the transaction period from “physical classroom” to “digital classroom” provoked by the pandemic of COVID-19. The use of information and communication technologies (hereinafter referred to as ICT), tools for online teaching and learning, computer and digital literacy, digital skills and competencies are becoming important components of professional success. The transition to distance learning (especially due to the pandemic of COVID-19) has changed the modern academic world: now the effective use of digital technologies and educational resources is considered a key factor for improving and increasing the value of the learning process. As a result, students get their knowledge and educators share their theoretical and practical experience through an increasing number of digital technologies and resources. This article aims to describe and analyze the main types of available online tools and services that may provide productive work and interactive learning; to describe the challenges that educators face while transforming the academic environment into “online classroom”. The authors applied a cabinet study approach to the analysis of theoretical database, the method of comparison and generalization of the obtained data. As aresult, the article presents theoretical background of the ICT potential and their use in the educational process of modern universities.
Lebensstil und kardiovaskuläre Gesundheit – wie schädlich sind E-Zigaretten und Shisha-Rauchen?
Authors: Kuntic Marin , Hahad Omar , Münzel Thomas , Daiber Andreas
Published: December 2021

Tabakrauchen ist ein Hauptauslöser chronischer nicht übertragbarer Krankheiten und ein Risikofaktor für kardiovaskuläre und pulmonale Erkrankungen. Obwohl der weltweite Tabakkonsum während der letzten 2 Jahrzehnte reduziert wurde, zeigt der Gebrauch von E-Zigaretten und Wasserpfeifen (Shisha) eine pandemische Zunahme mit hohem Anteil jüngerer Anwender. E-Zigaretten sind keine komplett schadensfreie Alternative zu herkömmlichen Tabakzigaretten, auch weil die zahlreichen Geschmacksaromen und die einfache/schnelle Verwendung eine steigende Zahl von abhängigen Anwendern hervorbringt. E-Zigaretten sind nicht unbedingt geeignet, die Nikotinabhängigkeit hinter sich zu lassen. Diese Arbeit bietet eine Übersicht über die kardiovaskulären Gesundheitsauswirkungen des Shisharauchens und E-Zigaretten-Dampfens mit Fokus auf die negativen Effekte auf die Endothelfunktion. Die schädlichen biologischen Auswirkungen der toxischen Inhaltsstoffe dieser Produkte werden vor allem im Hinblick auf
oxidativen Stress und Entzündungsreaktionen diskutiert. Abschließend wird der aktuelle Stand hinsichtlich der Empfehlungen, gesetzlichen Regelungen und kommerziellen Werbung kurz zusammengefasst.
Assessment of Sumatriptan on Sepsis-Induced Kidney injury in the
Cecal Ligation and Puncture Mice Model
Authors: Yousefi-Manesh Hasan , Shirooie Samira , Noori Tayebeh , Tavangar Seyed Mohammad , Sheibani Mohammad , Chaboki Alireza , Mohammadi Sina , Dehpour Ahmad Reza
Published: December 2021

Sepsis is a severe systemic inflammatory response with high mortality rate
resulting from different microorganisms. Cytokines activation is essential for
the immune response, but in painful conditions like sepsis, cytokines act as a
double-edged sword and dysregulate immune response which is life-threatening
owing to multiple organ dysfunction. The abnormality in 5-HT function is
involved in pathological conditions like irritable bowel syndrome, inflammation,
myocardial ischemia, itch and renal injury. Sumatriptan, a
5-HT1B/1D agonist, has anti-inflammatory and
anti-oxidative stress effects on animal models. This study was aimed to assess
the effects of sumatriptan on kidney injury, the levels of pro-inflammatory
cytokines and the percentage of survival in (CLP)-induced sepsis were
examined.

Cecal ligation and puncture (CLP) model was done on adult C57BL/6 male
mice to induce Polymicrobial sepsis. Sumatriptan was injected intraperitoneally
1 h after the sepsis induction by CLP at doses of 0.1, 0.3, and
1 mg/kg in 3 treatment groups. To study the effect of
sumatriptan on short-term survival, septic animals were detected 72 h
after CLP. Serum levels of TNF-α, IL-1β, IL-6 and IL-10 were
evaluated. To study sepsis-induced acute renal failure, kidney functional
biomarkers and histopathological alterations were evaluated.

Sumatriptan (0.3 mg/kg) administration significantly enhanced
survival rate (P<0.01) compared to the CLP group. The beneficial effects
of sumatriptan were related to a significant decrease in the pro-inflammatory
cytokines and elevated level of IL-10. Sumatriptan presented protective effects
on kidney biomarkers and histopathology assay.

Anti-inflammatory effects of sumatriptan lead to decrease mortality rate and
inflammatory cytokines in CLP induction sepsis in C57BL/6 mice.
Was verstehen wir unter Sekundärdaten? – Ein
Grundsatzbeitrag zur terminologischen Einordnung und Definition
Authors: Gothe Holger , Ihle Peter , Swart Enno
Published: December 2021

Daten sind für die Versorgungsforschung Material und Produkt zugleich.
Als „Substrat“ oder Ausgangsbasis von gesundheitsbezogenen
Analysen haben sie in den vergangenen Dekaden immens an Bedeutung gewonnen.
Für die Beurteilung von Leistungen des Gesundheitssystems, für
dessen Steuerung und Entwicklung sind Daten ein essenzieller Rohstoff. Im
wissenschaftlichen Alltag und in Forschungsarbeiten, die diesen Rohstoff nutzen,
kommt der Bedeutungsgehalt des Begriffs „Daten“ –
insbesondere „Sekundärdaten“ – oft zu kurz. Der
vorliegende Beitrag möchte den Bedeutungskontext der beiden Begriffe
vertiefend beleuchten und den Versuch unternehmen, den Begriff
„Sekundärdaten“ terminologisch einzuordnen.
Catalytic Amidomethylative [2+2+2] Cycloaddition of Formaldimine and Styrenes toward N-Heterocycles
Authors: Chaminda Lakmal Hetti Handi , Istre Jacob , Xu Xue , Cui Xin , Qian Xiaolin , Zhou Hui , Valle Henry U.
Published: December 2021

Chemo-switchable catalytic [2+2+2] cycloaddition of alkenes with formaldimines is reported. Bis(tosylamido)methane (BTM) and 1,2-ditosyl-1,2-diazetidine (DTD), two bench-stable precursors for highly reactive tosylformaldimine, have been identified to be effective. BTM worked as a selective releaser of the formaldimine for catalytic [2+2+2] reactions toward hexahydropyrimidine products via a presumable ‘imine–alkene–imine’ addition. A unique catalytic retro-[2+2] reaction of DTD was used and has enabled a proposed ‘imine–alkene–alkene’ pathway with high chemoselectivity for the synthesis of 2,4-di­arylpiperidine derivatives. The two alternative processes are catalyzed by the simple and environmentally benign catalysts InCl3 and FeBr2, respectively.
Penetration and Tensile Strength of Various Impression Materials of Vinylsiloxanether, Polyether, and Polyvinylsiloxane Impression Materials
Authors: Apinsathanon Pongsakorn , Bhattarai Bishwa Prakash , Suphangul Suphachai , Wongsirichat Natthamet , Aimjirakul Napapa
Published: December 2021

Objectives The aim of this study was to evaluate and compare penetration ability and tensile strength among vinylsiloxanether (VSE), polyether (PE), and polyvinylsiloxane (PVS) elastomeric dental impression materials.

Materials and Methods The models were constructed for penetration ability test by simulated gingival sulcus width and moist environment. The 0.05, 0.1, and 0.2 mm of simulated gingival sulcus widths were used. Each simulated gingival sulcus width was impressed 10 repeats per one elastomeric impression material. All extension of elastomeric dental impression materials was scaled by Measuring Microscope (MM-11; Nikon, Tokyo, Japan). On the issue of the tensile strength study, the models were constructed following type 1 of the ISO 37:2017 specifications and/or type C of ASTM.D412 specifications. The two-way analysis of variance (ANOVA) and Tukey's honest significant difference test were performed in the penetration ability test. The one-way ANOVA and Dunnett's T3 test were performed in the tensile strength test. The significance level was set at 0.05.

Results PE showed the best extension into all widths of simulated sulcus followed by VSE and PVS, respectively. PVS was significantly higher in tensile strength than VSE and PE, while VSE was significantly higher than PE.

Conclusion Penetration ability of elastomeric dental impression materials was depended on gingival sulcus width. The wider the sulcular width, the better the penetration ability of elastomeric dental impression materials. PE presented the best penetration ability, while the novel PVS showed highest tensile strength.
Combined Transcranial and Endoscopic Endonasal Approach for Resection of a Complex Sinonasal Squamous Cell Carcinoma: Two-Dimensional Operative Video
Authors: Nisson Peyton L. , Gaub Michael , Gonzales-Portillo Gabriel S. , Martirosyan Nikolay , Le Christopher , Lemole G. Michael
Published: December 2021

Sinonasal squamous cell carcinoma (SCC) is a rare head-and-neck neoplasm that has a propensity to locally invade vital structures. Currently, the combination of surgical resection and radiation remains the optimal treatment.1 However, the extent of disease burden and involvement of surrounding anatomy may make these inoperable. Here, we demonstrate the successful application of multidisciplinary approach for surgical resection of a large, complex SCC lesion centered at the superior nasal cavity with extension into the eye orbits and brain. A two-step approach was performed; transcribiform, endoscopic piecemeal resection with reconstruction of the skull base, followed by a bifrontal craniotomy. Reconstruction was achieved using an inlay of DuraMatrix allograft (Stryker Inc., Kalamzoo, Michigan, United States) followed by an inlay of AlloDerm (Allergan Inc., Irvine, California, United States), anchored anteriorly and posteriorly with wide wings placed over the respective orbital roofs. Major steps include (1) a summary of the patient presentation and preoperative imaging, (2) resection of the tumor endonasally, (3) resection of the tumor intracranially from a bifrontal craniotomy, and (4) a review of the postoperative imaging. The patient tolerated the procedure (Fig. 1) well, returned to his baseline with no new neurologic deficits, and was placed on 6-week antibiotics regimen for osteomyelitis discovered during the operation. Approximately, 2 months after discharge, the patient unfortunately returned with altered mental status, was found to have sepsis, and expired shortly thereafter. This operative video illustrates the technical steps and capabilities of surgical treatment, achieving near-complete gross total resection of a complex SCC lesion using a multidisciplinary approach.

The link to the video can be found at: https://youtu.be/8ffckKIuBzM.
Self-Reported Social Media Use among Ophthalmology Residents
Authors: Watane Arjun , Al-khersan Hasenin , Kalavar Meghana , Ahmed Bilal , Venincasa Michael , Sridhar Jayanth
Published: December 2021

Objective To assess ophthalmology trainees' self-reported use of and attitudes toward social media.

Methods An online survey was distributed by email to ophthalmology residency applicants of the Bascom Palmer Eye Institute between September 2016 and January 2020.

Results Of the 1,688 email recipients, the survey was filled by 208 ophthalmology trainees (12.3%). Nearly all trainees reported using social media for personal purposes (92.3%), while less than half used social media for professional purposes (43.4%). There were mixed sentiments regarding the impact of social media on the patient–physician relationship, with the majority feeling that it challenges a physician's authority (55.2%) but also empowers the patient (57.5%) and encourages shared care (92.8%). Twenty-five percent of trainees had reviewed professional social media guidelines, and most rated the quality of medical information on social media as “poor” (60.9%). There were low rates of trainees looking up patients (13.8%), providing their account information to patients (1.5%), responding to patients' messages (2.6%), following patients' accounts (2.6%), and being followed by patients (2.6%).

Conclusion The majority of ophthalmology trainees are active on social media. As these trainees enter practice, ophthalmology will likely see a rise in social media use. Training programs should consider a formal social media policy that is shared with all trainees as part of their education.
Trends in Ophthalmology Resident Operative Experience and the Early Impact of the COVID-19 Pandemic
Authors: Lauer Andreas K. , Chung Sophia M. , Tu Daniel C. , SooHoo Jeffrey R. , Potts John R.
Published: December 2021

Purpose This study aimed to evaluate trends in ophthalmology resident operative experience and the early impact of the novel coronavirus disease 2019 (COVID-19) pandemic.

Design Present study is a retrospective analysis of the Accreditation Council for Graduate Medical Education (ACGME) Case Log System.

Participants Anonymized graduating resident case logs from 2011 to 2020 academic years (AYs) were examined for this study.

Methods Regression analysis for each procedure category was performed to identify trends between 2011 and 2019 AYs. Unpaired two-tailed t-test compared 2018 to 2019 and 2019 to 2020 AY's for each category surgeon (S) and as surgeon and assistant (S + A).

Main Outcome Measures Mean and median cases as (S) and (S + A) during 2011 to 2019 AYs. Comparison between 2018 to 2019 and 2019 to 2020 AY's for each category as (S) and (S + A) to evaluate the impact of the COVID-19 pandemic.

Results Total ophthalmology procedures as (S) rose from a mean of 479.6 to 601.3 (p < 0.001; R 2 = 0.96; Δ/year = 16.9) and a median of 444 to 537 (p < 0.001; R 2 = 0.97; Δ/year = 13.1). Total procedures as (S + A) rose from a mean of 698.1 to 768 (p < 0.01; R 2 = 0.83; Δ/year = 9.07) and a median of 677 to 734 (p < 0.05; R 2 = 0.61; Δ/year = 6.64). Cataract procedures as (S) rose from a mean of 152.8 to 208 (p < 0.001; R 2 = 0.99; Δ/year = 7.98) and a median of 146 to 197 (p < 0.001; R 2 = 0.97; Δ/year = 7.87). Cataract procedures as both (S + A) rose from a mean 231.4 to 268.7 (p < 0.001; R 2 = 0.95; Δ/year = 5.5) and a median of 213 to 254 (p < 0.001; R 2 = 0.93; Δ/year = 5.33). Between 2018 to 2019 and 2019 to 2020 AYs, the first pandemic year was associated with significant reductions in total procedures (601.3–533.7 [p < 0.0001]) as (S) and 768.0 to 694.4 (p < 0.0001) as (S + A), cataract surgery (208–162.2 [p < 0.0001]) as (S) and 268.7 to 219.1 (p < 0.0001) as (S + A), and glaucoma surgery (16.3–14.2 [p = 0.0068]) as (S) and 25.6 to 22.6 (p = 0.0063) as (S + A).

Conclusion During 2011 to 2019 AYs, cataract, intravitreal injections, glaucoma, and total procedures increased significantly. During the early period of the COVID-19 pandemic (2019–2020 AY), national halting of elective procedures had a precipitous effect on resident cataract surgery experience to volumes similar to 2013 to 2014 AY where the mean was twice the current required minimum number. With few exceptions, other procedure volumes remained stable.
Racial Disparities in the Rates of and Indications for Cesarean Delivery in California: Are They Changing Over Time?
Authors: Teal E. Nicole , Anudokem Kelechi , Baer Rebecca J. , Jelliffe-Pawlowski Laura , Mengesha Biftu
Published: December 2021

Objective The aim of this study was to assess whether racial disparities in rates of and indications for cesarean delivery (CD) between non-Hispanic Black and non-Hispanic White birthing people in California changed from 2011 to 2017.

Methods This was a retrospective cohort study using a database of birth certificates linked to discharge records. Singleton term live births in nulliparous Black and White birthing people in California between 2011 and 2017 were included. Those with noncephalic presentation, placenta previa, and placenta accreta were excluded. CD rate and indication were obtained from birth certificate variables and International Classification of Diseases codes. Differences in CD rate and indication were calculated for Black versus White individuals using univariable and multivariable logistic regression and adjusted for potential confounders.

Results A total of 348,144 birthing people were included, 46,361 Black and 301,783 White. Overall, 30.9% of Black birthing people underwent CD compared with 25.3% of White (adjusted relative risk [aRR]: 1.2, 95% confidence interval [CI]: 1.2–1.3). From 2011 to 2017, the CD rate fell 11% (26.4–23.7%, p < 0.0001) for White birthing people and 1% for Black birthing people (30.4–30.1%, p = 0.037). Over the study period, Black birthing people had a persistent 1.2- to 1.3-fold higher risk of CD and were persistently more likely to undergo CD for fetal intolerance (aRR: 1.1, 95% CI: 1.1–1.2) and less likely for active phase arrest or arrest of descent (aRRs: 0.9 and 0.4; 95% CIs: 0.9–0.9 and 0.3–0.5).

Conclusion The CD rate decreased substantially for White birthing people and minimally for Black birthing people in our cohort over the study period. Meanwhile, disparities in CD rate and indications between the two groups persisted, despite controlling for confounders. Although care bundles for reducing CD may be effective among White birthing people, they are not associated with reduction in CD rates among Black birthing people nor improvements in racial disparities between Black and White birthing people.

Precis Despite increasing attention to racial inequities in obstetric outcomes, there were no changes in disparities in CD rates or indications in California from 2011 to 2017.

Key Points
Changes in the Antenatal Utilization of High-Risk Obstetric Services and Stillbirth Rate during the COVID-19 Pandemic
Authors: Oakes Megan C. , Zhang Fan , Stevenson Lori , Porcelli Bree , Carter Ebony B. , Raghuraman Nandini , Kelly Jeannie C.
Published: December 2021

Objective The primary objective of this study was to evaluate coronavirus 2019 (COVID-19) pandemic–related changes in the antenatal utilization of high-risk obstetric services. Our secondary objective was to characterize change in stillbirth rate during the pandemic.

Study Design This is a retrospective, observational study performed at a single, tertiary care center. Maternal-Fetal Medicine (MFM) visits, ultrasounds, and antenatal tests of fetal well-being during the pandemic epoch (2020), which spans the first 12 weeks of the year to include pandemic onset and implementation of mitigation efforts, were compared with the same epoch of the three preceding years visually and using general linear models to account for week and year effect. An analysis of stillbirth rate comparing the pandemic time period to prepandemic was also performed.

Results While there were decreased MFM visits and antenatal tests of fetal well-being during the pandemic epoch compared with prepandemic epochs, only the decrease in MFM visits by year was statistically significant (p < 0.001). The stillbirth rate during the pandemic epoch was not significantly different when compared with the prepandemic period and accounting for both week (p = 0.286) and year (p = 0.643) effect.

Conclusion The COVID-19 pandemic resulted in a significant decrease in MFM visits, whereas obstetric ultrasounds and antenatal tests of fetal well-being remained unchanged. While we observed no change in the stillbirth rate compared with the prepandemic epoch, our study design and sample size preclude us from making assumptions of association. Our findings may support future work investigating how changes in prenatal care for high-risk obstetric patients influence perinatal outcomes.

Key Points
A Scoping Review of Perinatal Palliative Care: Allowing Parents to Be Parents
Authors: Buskmiller Cara , Calhoun Byron C.
Published: December 2021

Objective Perinatal palliative care (PPC) is an option for patients who discover that their infant has a life-limiting fetal condition, which decreases the burden of the condition using a multidisciplinary approach.

Study Design This review discusses the landmark literature in the past two decades, which have seen significant growth and development in the concept of PPC.

Results The literature describes the background, quality, and benefits of offering PPC, as well as the ethical principles that support its being offered in every discussion of fetal life-limiting diagnoses.

Conclusion PPC shares a similar risk profile to other options after life-limiting diagnosis, including satisfaction with choice of continuation of pregnancy. The present clinical opinion closes by noting common barriers to establishing PPC programs and offers a response to overcome each one.

Key Points
Investigating photomultiplier tube nonlinearities in high-speed phosphor thermometry using light emitting diode simulated decay curves
Authors: Feuk Henrik , Nilsson Sebastian , Aldén Marcus , Richter Mattias
Published: December 2021

Photomultiplier tube (PMT) nonlinearities relevant for single shot high-speed lifetime phosphor thermometry were investigated by simulating decay curves with a light emitting diode (LED) at repetition rates between 1 Hz and 10 kHz. The PMT gain, LED decay time, and background radiant flux were also varied to investigate their impact on the measured decay time error. Errors in the measured decay time due to nonlinear PMT performance lead to temperature measurement errors; therefore, having the measured decay time sensitive to only phosphor temperature is highly valuable for more reliable temperature measurements. Photocathode bleaching had a significant impact on the signal level linearity for PMTs with excitation frequency in the kHz regime but had a smaller impact on the decay time error. Space charge effects were most noticeable at high radiant flux levels and high repetition rates. Strong background radiant flux may lead to decay time errors, and a gateable photocathode could be an effective method to reduce decay time errors. The best decay time measurement configuration to maximize precision without sacrificing accuracy is to use PMT gain in the recommended range and the highest radiant flux where the PMT response is still linear. The degree of nonlinearity in the PMT response is partly detector dependent; therefore, the results in this work may differ among detectors; however, the analysis presented in this work provides guidelines for improving the temperature accuracy of kHz lifetime phosphor thermometry measurements.
Creation of single chiral soliton states in monoaxial helimagnets
Authors: Osorio S. A. , Laliena V. , Campo J. , Bustingorry S.
Published: December 2021

In monoaxial helimagnets, the Dzyaloshinskii–Moriya interaction favors inhomogeneous distributions of the magnetization with chiral modulations of solitonic character. In addition to the helical magnetic state at zero field, a chiral soliton lattice can be stabilized when a magnetic field perpendicular to the chiral axis is applied. When the magnetic field is increased, the system undergoes a phase transition to the uniform state at a critical field Bc. Above Bc, a single chiral soliton comprises the lowest level excitation over the stable uniform state, surviving as a metastable configuration. How to retain a single chiral soliton metastable state has not been addressed yet. Using micromagnetic simulations, we analyze this possibility by injecting spin polarized currents and put forward a feasible protocol to obtain a state with a single chiral soliton from the chiral soliton lattice. Our proposal could be relevant in the experimental study of metastable solitons for technological applications.
Transient radial spray from electrified viscous jets
Authors: Ke Shiyou , Jin Panlin , Xu Shumin , Yin Xieyuan , Yin Xiezhen , Li Fang
Published: December 2021

An applied radial electric field can influence the instability and breakup behavior of a liquid jet. Particularly, when the electric field is sufficiently strong, a multi-cone-jet structure can be formed: a number of Taylor cones arise transiently at the equator of the most deformed droplet in the jet; from the tip of each cone, a fine secondary jet is emitted, which quickly breaks up into micrometer-sized progeny droplets. This tip streaming phenomenon is experimentally investigated for finitely conducting, viscous liquid jets in the present work. Different regimes are distinguished in the Be (the electric Bond number)-We (the Weber number) plane and also in the Be-We-Oh (the Ohnesorge number) space. The results show that both viscosity and inertia have a suppression effect on the formation of a multi-cone-jet structure. Moreover, the number of secondary jets can be greatly reduced by increasing viscosity or inertia. Increasing electrical conductivity leads to intense spray of secondary jets. In addition, some interesting phenomena like the coalescence of secondary jets and the coexistence of axisymmetric and non-axisymmetric instability are observed.
Impact of surface nanostructure and wettability on interfacial ice physics
Authors: Nikiforidis Vasileios-Martin , Datta Saikat , Borg Matthew K. , Pillai Rohit
Published: December 2021

Ice accumulation on solid surfaces is a severe problem for safety and functioning of a large variety of engineering systems, and its control is an enormous challenge that influences the safety and reliability of many technological applications. The use of molecular dynamics (MD) simulations is popular, but as ice nucleation is a rare event when compared to simulation timescales, the simulations need to be accelerated to force ice to form on a surface, which affects the accuracy and/or applicability of the results obtained. Here, we present an alternative seeded MD simulation approach, which reduces the computational cost while still ensuring accurate simulations of ice growth on surfaces. In addition, this approach enables, for the first time, brute-force all-atom water simulations of ice growth on surfaces unfavorable for nucleation within MD timescales. Using this approach, we investigate the effect of surface wettability and structure on ice growth in the crucial surface–ice interfacial region. Our main findings are that the surface structure can induce a flat or buckled overlayer to form within the liquid, and this transition is mediated by surface wettability. The first overlayer and the bulk ice compete to structure the intermediate water layers between them, the relative influence of which is traced using density heat maps and diffusivity measurements. This work provides new understanding on the role of the surface properties on the structure and dynamics of ice growth, and we also present a useful framework for future research on surface icing simulations.
Mass ratio effect on vortex-induced vibration for two tandem square cylinders at a low Reynolds number
Authors: Qiu Tao , Lin Weiqun , Du Xiaoqing , Zhao Yan
Published: December 2021

A numerical simulation study is conducted to investigate the effect of the mass ratio (m* = 3, 10, and 20) on vortex-induced vibration (VIV) of two tandem square cylinders at Re = 150. In this study, we mainly focus on the mass ratio effect on the vibration response, force characteristics, wake mode pattern, and fluid–structure-interaction (FSI) mechanism. The results show that mass ratio plays an important role in the VIV response of the two cylinders. With increasing reduced velocity, both the upstream cylinder (UC) and downstream cylinder (DC) at m* = 3 exhibit the soft-lock-in phenomenon (at a lock-in frequency ratio of fy/fn < 1) instead of the typical lock-in phenomenon (at a lock-in frequency ratio of fy/fn ≈ 1). With increase in the mass ratio to m* = 10 and 20, the soft-lock-in phenomenon disappears, while the DC exhibits the typical lock-in phenomenon. The maximum amplitudes of the two cylinders notably decrease with increasing mass ratio. Furthermore, the mass ratio exerts a major impact on the distance between the two cylinders, which may change the flow pattern. The distance sharply decreases in the synchronization region at m* = 3 but remains almost constant at m* = 10 and 20. In addition, the wake mode and FSI mechanism are more diverse at a low mass ratio (m* = 3).
Multiphase flow simulation with three-dimensional weighted-orthogonal multiple-relaxation-time pseudopotential lattice Boltzmann model
Authors: Tang Jun , Zhang Shengyuan , Wu Huiying
Published: December 2021

In this paper, based on two lattice models (D3Q19 and D3Q27), two three-dimensional weighted-orthogonal multiple-relaxation-time pseudopotential lattice Boltzmann (WMRT-PLB) models with tunable thermodynamic consistency and surface tension are developed in which the high-order terms of the equilibrium density distribution function and discrete forcing term in moment space are eliminated, and thus, the implementation of the collision process is simplified. The Chapman–Enskog analysis shows that the WMRT-PLB models can correctly recover the macroscopic Navier–Stokes equations in the low Mach number limit. Then, six classical multiphase flows benchmark cases are performed to validate the performance of the proposed model. The numerical results of the first three cases indicate that the developed WMRT-PLB models effectively weaken the non-physical coupling between kinetic viscosity and density, enhance the numerical stability because of the low spurious velocity, improve the computational efficiency by about 25% because of the simplification of the collision process, and increase the numerical accuracy in the dynamic problems. Meanwhile, the numerical results of the last three cases with the density ratio of 857.7 and the kinetic viscosity ratio of 1/15 agree well with the analytical solutions and experimental results reported in the literature. Note that it is also found that the simulation of droplet bouncing is still stable even when the Reynolds number is more than 3000, which shows the good numerical stability of the proposed model. It has the potential to be applied to the simulation of the complex multiphase flows with large density ratio and large Reynolds number.
Self-trapping in bismuth-based semiconductors: Opportunities and challenges from optoelectronic devices to quantum technologies
Authors: Rondiya Sachin R. , Jagt Robert A. , MacManus-Driscoll Judith L. , Walsh Aron , Hoye Robert L. Z.
Published: December 2021

Semiconductors based on bismuth halides have gained attention for a wide range of electronic applications, including photovoltaics, light-emitting diodes, and radiation detectors. Their appeal is due to their low toxicity, high environmental stability under ambient conditions, and easy processability by a wide range of scalable methods. The performance of Bi-based semiconductors is dictated by electron–phonon interactions, which limit carrier mobilities and can also influence optoelectronic performance, for example, by giving rise to a large Stokes shift for photoluminescence, unavoidable energy loss channels, or shallow optical absorption onsets. In this Perspective, we discuss the recent understanding of how polarons and self-trapped excitons/carriers form in Bi-based semiconductors (particularly for the case of Cs2AgBiBr6), their impact on the optoelectronic properties of the materials, and the consequences on device performance. Finally, we discuss the opportunities that control of electron–phonon coupling enables, including stable solid-state white lighting, and the possibilities of exploiting the strong coupling found in bipolarons for quantum technologies.
Modeling of effective interactions between ligand coated nanoparticles through symmetry functions
Authors: Chintha Dinesh , Veesam Shivanand Kumar , Boattini Emanuele , Filion Laura , Punnathanam Sudeep N.
Published: December 2021

Ligand coated nanoparticles are complex objects consisting of a metallic or semiconductor core with organic ligands grafted on their surface. These organic ligands provide stability to a nanoparticle suspension. In solutions, the effective interactions between such nanoparticles are mediated through a complex interplay of interactions between the nanoparticle cores, the surrounding ligands, and the solvent molecules. While it is possible to compute these interactions using fully atomistic molecular simulations, such computations are too expensive for studying self-assembly of a large number of nanoparticles. The problem can be made tractable by removing the degrees of freedom associated with the ligand chains and solvent molecules and using the potentials of mean force (PMF) between nanoparticles. In general, the functional dependence of the PMF on the inter-particle distance is unknown and can be quite complex. In this article, we present a method to model the two-body and three-body PMF between ligand coated nanoparticles through a linear combination of symmetry functions. The method is quite general and can be extended to model interactions between different types of macromolecules.
A reactive flow model for the 3,3′-diamino-4,4′-azoxyfurazan based plastic bonded explosive (PBX 9701)
Authors: Price Matthew A. , Leiding Jeffery A. , Aslam Tariq D. , Coe Joshua D. , Ramos Kyle J. , Bolme Cynthia A. , Francois Elizabeth G. , Lichthardt Joseph P. , Bowden Pat P. , Thompson Darla G. , Ticknor Christopher
Published: December 2021

This paper describes the calibration of the Arrhenius Wescott–Stewart–Davis (AWSD) reactive flow model for the recently developed high explosive PBX 9701, which consists of 97% 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3% FK-800 binder by weight. DAAF-based explosive formulations have several desirable qualities as they are relatively insensitive to non-shock insults but have higher performance than triaminotrinitrobenzene based formulations. Equations of state for the explosive reactants and products are calibrated using a combination of existing and new experimental data and theoretical calculations. The AWSD rate law calibration utilizes both one-dimensional shock-to-detonation and multidimensional rate stick experiments to capture the shock initiation and propagating detonation regimes. Validation of the calibrated model is demonstrated through comparison with recent gas-gun experiments.
Comparative study of the effect of van der Waals interactions on stacking fault energies in SiC
Authors: Sakakima Hiroki , Hatano Asuka , Izumi Satoshi
Published: December 2021

Van der Waals (vdW) interactions have recently been demonstrated to have a non-negligible effect on the theoretical polytype stability and stacking fault energies of SiC. Calculations with density functional theory have been demonstrated to reproduce polytype stability consistent with experimental results when vdW interactions are considered. The effect of vdW interactions on stacking fault energies in SiC is an important engineering issue; however, it has not been studied in detail. Since previous studies used vdW correction methods that are rather simple and semi-empirical, the application of more sophisticated correction strategies and comparison among several proposed methods is required. In this study, we examined the dependence of polytype stability on the vdW correction method. While most methods could reproduce the polytype stability order, the extensively used DFT-D3 and its variants could not since the computed dependence of vdW interaction energy on hexagonality of SiC was small. Then, we examined the stacking fault energies considering vdW interactions. The vdW interactions were found to have a significant effect on the stacking fault energies only when the insertion of stacking faults changes the local hexagonality. The vdW interactions were found to cause negative energy for double Shockley-type stacking faults (DSSFs) in 4H-SiC. This negative energy is inconsistent with the electric energy model for the spontaneous expansion of DSSFs, which assumes that the stacking fault energy is inherently positive. Our results indicate that previous theoretical models may require being modified.
Terahertz-field-induced second harmonic generation for nonlinear optical detection of interfaces buried in transparent materials
Authors: Bodrov S. B. , Stepanov A. N. , Burova E. A. , Sergeev Yu. A. , Korytin A. I. , Bakunov M. I.
Published: December 2021

We propose and demonstrate experimentally a nonlinear optical technique that allows for detection and characterization of invisible (or low-contrast) microscale objects buried in the bulk of materials transparent in the optical and terahertz frequency ranges. The technique is based on the effect of terahertz-field-induced second harmonic generation and uses collinearly propagating femtosecond optical and picosecond terahertz pulses to probe a sample. Due to a difference between the optical and terahertz velocities, the pulses can be overlapped in different regions of the sample by varying the time delay between them. Overlapping in the bulk of the material does not produce optical second harmonic emission, whereas overlapping at the microobject does produce the emission. The technique was verified experimentally for two plates of fused quartz glued by a thin (15–35 μm thick) layer of optical adhesive. The presence of the adhesive was detected, and its third-order nonlinear susceptibility was measured.
Spatio-temporal ablation dynamics and plasma chemistry of aluminum induced by temporally modulated ytterbium fiber laser
Authors: Park Minok , Balkey Matthew M. , Mao Xianglei , Grigoropoulos Costas P. , Zorba Vassilia
Published: December 2021

In this work, we studied single-pulse ablation dynamics of a temporally modulated continuous wave laser–material interaction with Al using in situ multimodal time-resolved diagnostics that describe in detail the associated physical and chemical processes. Time-resolved scattering, emission imaging, and optical emission spectroscopy unveiled a sequence of events spread out across three distinct phases: (i) early phase ablation process, associated with particle generation and liquid Al column formation (<20 μs), (ii) secondary detonation when sufficient ejected material is accumulated over the surface (20–50 μs), and (iii) molten liquid Al pool oscillation on the surface, followed by large droplet ejection from the liquid pool (100–500 μs). Atomic Al and AlO were observed with optical emission spectroscopy at different ratios during the entire lifetime of the event, verifying the formation of oxidized Al vapor upon its interaction with air. Morphological and compositional characterization confirmed surface oxidation and material re-solidification in the form of protrusions produced during the irradiation process. This work provides insights into the complex physical and chemical mechanisms of single-pulse ablation in the sub-millisecond laser pulse regime, which are critically important for parameter optimization in a variety of laser processing, microfabrication, and deposition applications.
Small size effects in open and closed systems: What can we learn from ideal gases about systems with interacting particles?
Authors: Bråten Vilde , Bedeaux Dick , Wilhelmsen Øivind , Schnell Sondre Kvalvåg
Published: December 2021

Small systems have higher surface area-to-volume ratios than macroscopic systems. The thermodynamics of small systems therefore deviates from the description of classical thermodynamics. One consequence of this is that properties of small systems can be dependent on the system’s ensemble. By comparing the properties in grand canonical (open) and canonical (closed) systems, we investigate how a small number of particles can induce an ensemble dependence. Emphasis is placed on the insight that can be gained by investigating ideal gases. The ensemble equivalence of small ideal gas systems is investigated by deriving the properties analytically, while the ensemble equivalence of small systems with particles interacting via the Lennard-Jones or the Weeks–Chandler–Andersen potential is investigated through Monte Carlo simulations. For all the investigated small systems, we find clear differences between the properties in open and closed systems. For systems with interacting particles, the difference between the pressure contribution to the internal energy, and the difference between the chemical potential contribution to the internal energy, are both increasing with the number density. The difference in chemical potential is, with the exception of the density dependence, qualitatively described by the analytic formula derived for an ideal gas system. The difference in pressure, however, is not captured by the ideal gas model. For the difference between the properties in the open and closed systems, the response of increasing the particles’ excluded volume is similar to the response of increasing the repulsive forces on the system walls. This indicates that the magnitude of the difference between the properties in open and closed systems is related to the restricted movement of the particles in the system. The work presented in this paper gives insight into the mechanisms behind ensemble in-equivalence in small systems, and illustrates how a simple statistical mechanical model, such as the ideal gas, can be a useful tool in these investigations.