bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical conductivity of cement mortar with the addition of graphene
Authors: Potses Tatiana , Novikov Vladimir , Sergeev Kirill , Leonovich Sergey
Published: December 2021

With the development of technological innovations in the field of construction, increasing the efficiency of energy-saving materials used, more and more attention is paid to electrically conductive materials. Electrical conductivity studies were carried out on samples of concrete with graphene addition to obtain the current–voltage characteristics of the material. In order to identify the mechanism of the effects of different concentrations of graphene on electrical conductivity, a series of samples with different concentrations of graphene was made. As a result of the research, it was found that the dependence: the resistivity of the materialthe concentration is percolation, the concentration of graphene in the amount of 8% of the mass of cement is the percolation threshold.
The compressive strength of steel fibre reinforced concrete obtained by testing cubes and cylinders
Authors: Sadouskaya Alena , Leanovich Syarhei , Budrevich Neli , Polonina Elena
Published: December 2021

There are two most popular approaches to determining the compressive strength of concrete: testing cubes, testing cylinders. The use of different samples gives different results, which are intended to characterize one parameter of the material compressive strength. The article discusses a general approach to determining the compressive strength of cylinders and cubes. The analysis of the factors influencing the transition coefficients when testing the cylinder samples with the ratio of height to diameter is less than 2. The results of testing cubes and cylinders for compression made of fiber-reinforced concrete are presented.
The modified early age strains development model for the case of two-way restraint conditions
Authors: Sannikava Volha , Tur Viktar
Published: December 2021

This paper proposes a design model (2D MSDM) for assessment the early-age stress-strain parameters of two-axially restrained expansive concrete elements. The analytical model allows defining the restrained expansion strains and corresponding self-stresses in case of arbitrary restraint conditions in orthogonal directions by taking into consideration the elastic-plastic behavior of concrete during the expansion period. The results of solution according to the proposed model were compared with the experimental results of expansive concrete elements with orthogonal confinement carried out by authors and other researchers.
Assessment of the existing reinforced concrete structures with usage of the fuzzy logic – based expert system
Authors: Tur Viktar , Dardziuk Yuliya
Published: December 2021

Fuzzy logic is the useful tool when assessing the existing reinforced concrete structures. The introduction of expert system in assessing the technical condition of the existing structures built on the fuzzy logic represents a transition to a new and higher-quality level for survey of constructions sites. As a result, it is seen that the assessment of the existing building with usage of the proposed expert system is in compliance with the estimation of the qualified experts.
Foreign languages training features in digital environment of non-linguistic universities
Authors: Zaitsev Aleksei Anatolievich , Babushkina Larisa Evgenievna , Takanova Olga Vladimirovna , Vasilchenko Tatiana Anatolievna , Ryabchikova Vera Georgievna
Published: December 2021

The research is devoted to identifying the features of foreign languages training of non-linguistic universities students in the digital environment. The analysis of theory and practice on the research problem allows us to highlight a number of features that affect the formation of foreign language competence of non-linguistic universities students in the foreign languages training. It is worth including among them: updating the multicultural component of foreign languages training in a non-linguistic university; implementation of purposeful work on extracurricular preparation of students for the digital tools using; an electronic information and educational environment creation. The authors emphasize the importance of the multicultural component in foreign languages training, as it contributes to the development of the potential abilities of the students’ linguistic personality. Considering the second feature, the authors especially note that the use of digital tools provides great opportunities for the implementation of a method that most fully reflects the two main principles of the communicative approach to foreign languages training: motivation for learning and personal interest. Students are willingly involved in cognitive activities. The authors associate the third feature with the ability of students to work independently, since it is the independence that makes it possible to successfully adapt to work associated with rapidly changing technologies. This skill is especially important in correspondence or distance learning, when the student’s communication with the teacher is irregular. The presented features, according to the authors, make it possible to change the motivational attitude towards educational and future professional activities.
Pedagogical ethics in distance education
Authors: Chernova Irina Valerievna , Katermina Veronika Viktorovna
Published: December 2021

2020 was a truly revolutionary year in terms of education – from the paradigm of predominantly traditional education, we had to rapidly “step” into a distance format, regardless of our desire and readiness. In 2020 two tectonic shifts happened at once: the shift from synchronous offline classes (education) to synchronous online and then from synchronous formats to asynchronous and mixed. In addition to issues related to the technical support of the educational process, the issue related to the development of new professional and pedagogical principles and rules that would contribute to the highly moral behavior and activities of the teacher in creating a comfortable environment for all participants of distance learning process, emphasizing that ethical requirements must reflect the relationship between teachers and learners. We conducted a research aimed at revealing the principles and values the teachers consider crucial to follow when conducting online classes, the skills they think they need master in order to raise the level of their professional expertise, improve the effectiveness of teaching and learning processes, and make their students self-confident and independent. The results of the survey can be used in designing special courses devoted to professional or pedagogical ethics in online learning.
Public diplomacy in language education during the COVID-19 pandemic
Authors: Yudina Natalya Vladimirovna , Seliverstova Oksana Aleksandrovna
Published: December 2021

The pandemic has had a considerable impact on all spheres of life. Likewise, it has affected all levels of education changing conventional interaction patterns. The new format of learning influenced the motivation on the whole and its components in particular. The paper presents results of the survey conducted among students of Linguistics that contains self-assessment of motivation for FL learning in general and at the time of pandemic during distance learning. The reported overwhelming opinion concerning the lack of proper communication in the new settings along with an overall decline in all types of motivation is forcing the faculty to look for new ways of encouraging language learning and compensate for the absence of face-to-face classes. In solving this problem, the resources of public diplomacy appeared to be a very helpful tool. The paper explores changes in the language learning process both from the teachers’ and
students’ standpoint. It also gives a comparative overview of motivation types in conventional learning settings and distance-learning ones. The authors focus on the potential benefits of public diplomacy contacts in language learning.
Game-based language learning in the context of distance education
Authors: Levina Natalia Nikolaevna , Petrenko Tatyana Philippovna , Airapetov Gurgen Eduardovich , Ryashchenko Marina Aleksandrovna
Published: December 2021

The abrupt transition of the educational institutions to distance learning because of objective reasons related to the Covid-19 pandemic and the social isolation required the teachers to review the existing approaches to the classes organization and make appropriate changes. Rethinking traditional methods with game-based technologies expect not to “lose” contact with the audience and maintain its learning motivation. This study aims to generalize the experience of game-based technologies incorporation in university French classes at different levels to preserve and enhance the students learning motivation in the context of distance education. The scientific problem considered in the article fits into the problems of research aimed at studying the effective teaching methods and technologies that contribute to forming the students’ motivation. To achieve the research goal, the inductive-deductive method is used, as well as the methods of situational analysis. The analysis of existing approaches to the motivation phenomenon allowed the authors to define its importance in teaching foreign languages and to determine the role of the game-based methods in learning motivation enhancement. The result of the study is a demonstration of applied game-based technologies and their positive impact on learning motivation during distance education.
Linguodidactic potential of Microsoft Teams applications for teaching English vocabulary
Authors: Osipova Ekaterina Sergeevna , Bagrova Ekaterina Yuryevna
Published: December 2021

The paper analyzes the existing research and case studies of using Microsoft 365 Teams (MS Teams) for educational purposes while teaching English as a Foreign Language (EFL) during distance learning in the midst of the Covid-19 pandemic and provides an introduction to the innovative use of MS Teams. The given article reveals some aspects of implementing Microsoft Teams applications (MS Teams apps) with a strong linguodidactic potential (Collaboard, WordClouds, Mindomo, Kahoot, Flipgrid, Quizlet, myQuiz, Fortune Cookie) in university students’ vocabulary teaching. The authors underline the methodological value of the abovementioned MS Teams apps and give some examples of the linguodidactic use of MS Teams apps in their own EFL teaching practice. Data were collected following the methods of theoretical analysis, the educational experiment was conducted following the empirical methods. The study provides an algorithm for a new way of teaching vocabulary to EFL students during distance learning and indicates which MS Teams apps can be used in terms of the stage of teaching vocabulary, exercise type, and activity type. As a result, the most optimal combination of using MS Teams apps to teach vocabulary during distance learning has been revealed: Collaboard, Mindomo (preparation) + Quizlet, WordClouds (presentation) + myQuiz, Kahoot (practice) + Flipgrid, Fortune Cookie (production).
Methodological aspects of teaching the basics of intercultural communication
Authors: Musagulova Ryskul Ekinovna , Chernichenko Irina Arkadievna , Yakovleva Polina Petrovna , Yefremtseva Tatyana Nikolaevna , Alipichev Aleksei Yurievich
Published: December 2021

The article considers the training method for teaching professionally oriented and intercultural communication. The use of training sessions during the study of educational topics in the classroom activates the students’ work, helps to consolidate the theoretical knowledge obtained, and motivates students for independent, collective, team work. There is no universally recognized classification of training. The article considers the division of training into three types: educational, personal, and professional. All these three types of training are used by the authors as the final stage of work on a certain topic. The work using the training method is described by the example of teaching students in the discipline “Professionally oriented foreign language”, which consists of two modules: professional communication and intercultural communication. The article provides examples of training in the first and second modules. In the first module, training helps to consolidate the so-called “flexible skills”, which cover the following topics: leadership, the ability to manage, criticize, resolve conflicts, speak publicly, persuade, negotiate, hold small-talk conversations, be a business person, learn from animals, birds, have business qualities of a leader. In the second module, students get acquainted with training on intercultural communication; learn to deal with people of other cultures, with the peculiarities of cultures, and with mistakes that can be made at the intercultural level.
Teaching intercultural communication through associative fields of professional vocabulary
Authors: Stozhok Ekaterina Viktorovna , Khalevina Svetlana Nikolaevna , Kozlovtseva Nina Aleksandrovna , Glushkova Nadezhda Mamatkulovna
Published: December 2021

In the era of globalization and social distancing, intercultural dialogue plays a crucial role and requires a thorough reinterpretation. It is impossible without foreign language proficiency. Therefore, teaching foreign languages is a key to professional competency and personal growth. Language reflects the culture and functions as a universal tool of mutual understanding. It makes it possible to embrace the interlocutor’s mentality through grasping the peculiarities of the language. The proposed article is devoted to the validity study of the associative field technique. Its application contributes to the successful memorizing of terms and terminological expressions in a foreign language. The research considers the corresponding theoretical background devoted to the issues of intercultural communication, associative fields, and metaphorization of terms and terminological expressions in English. The methods applied in the study include comparative analysis, the method of continuous sampling, and a questionnaire survey. After the survey, the authors identified the terms that evoke associations with the notions “death” and “dead”. The article contains a number of interim conclusions with a further perspective on this issue. It is determined that the notion of “death” stands out as a representative of the “naïve” picture of the world and an initially expressive concept. In the case of a formal concept, the notion functions as a successful component of terms, especially metaphorical ones. The results of the study may be implemented in teaching a foreign language and intercultural communication, as well as in comparative linguistics and cultural studies.
Crystallisation of meaning as a technique for forming intercultural communicative competence within the real–virtual dichotomy
Authors: Cherkasova Inna Petrovna , Reva Tatiana Nikolaevna , Palanchuk Nadezhda Valerievna , Pashneva Svetlana Aleksandrovna , Kozhevnikova Margarita Anatolievna
Published: December 2021

The article explores the formation of intercultural communicative competence within the framework of the “real – virtual” dichotomy. The principal instrument of formation is the meaning crystallisation technique based on the material of media discourse as well as computer and art-specific types of discourse. The discourse is viewed as a complex structural and semantic formation, an axiological system that has a definite functional perspective; it represents itself as a domain for realisation of specific values or their facets depending on the situational context, as actualisation of interaction between textual structures and extra-linguistic factors. The discourse is based on the system of concepts relevant for intercultural communication. The concept is a totality of meanings representing an axiological category that is important within the space of a particular discourse. Language is social and pragmatic in its core; therefore, the substantive and semantic aspects of linguistic units are connected with socio-cultural factors, the ways of vision and comprehension of objects. The relevance of research in this sphere is determined by: 1) the growing interest in the problems of dialogue of cultures and intercultural communication; 2) the attention of researchers to the structural and semantic organisation of discursive spheres; 3) the specificity of communication types that have a significant impact on the social worldview; 4) the importance of identification and formation of axiological benchmarks in the society; 5) the features related with extension of the virtual interaction sphere. Crystallisation is principally a process in which interpretation is used to trace the semantic content of words that, in the context of thinking or art, becomes independent of the norm fixed by dictionary definitions. The study of crystallisation processes involves the analysis of concepts in terms of dialogue of cultures. Concepts are verbalised in accordance with the nature and uniqueness of material, spiritual and social culture, in close connection with linguistic and pragmatic components. The research results can be used in courses on foreign language teaching methodology, theory and practice of intercultural communication, discourse theory, stylistics, and interpretation of texts.
Reflecting national identity in universal concepts
Authors: Aleshina Larisa Nikolaevna , Zaytseva Irina Aleksandrovna , Smakhtin Evgeniy Sergeevich , Gilovaya Elena Anatolyevna , Lapshina Svetlana Sergeevna
Published: December 2021

The issue of reflecting national mentality in the linguistic worldview continues to be relevant as each people has its own specific mindset and common mood related to moral and ethical features of its formation. The article describes a national concept as a complete combination of thought, religions, cultural traditions, folklore that form a conceptual sphere of a language. Therefore, studying the reflection of national identity in the concepts seems to be essential, as the concept itself is a key category in linguistic research of viewing the world through language. The main purpose of this study is to perform a comparative analysis of conceptual spheres of the Russian and English languages. To achieve this purpose we set several tasks: to characterize peculiarities of expressing the key concepts sovest’/conscience, dobro/good, pravda/truth, krasota/beauty in speech; to identify extralinguistic factors fostering common understanding of the conceptual spheres being analyzed in the Russian and English linguistic worldviews. The article uses a complex research methodology, which combines descriptive and analytical methods, as well as the opposition technique and structural and semantic analysis of a word. The paper concludes that only those connotations of the concepts that become a symbol referring to a certain perspective of national mentality are ethnoculturally essential. In the conceptual spheres of English and Russian, key notions defining value systems of these cultures play a significant role. Evolution of material and spiritual culture is reflected in a concept as a single linguistic unit.
Teacher-student cooperation boosting grammar in the age of Big Data
Authors: Golubkova Ekaterina Evgenievna , Salkova Marina Alekseevna , Machina Olga Arkadievna , Pavlyuk Olga Nikolaevna , Trubochkin Aleksandr Vladimirovich
Published: December 2021

The article focuses on the new language teaching and learning strategies offered by the use of corpora-based method. It gives an insight into how a corpus-based research incorporated into English grammar classroom activities not only clarifies the debatable aspects of traditional grammar rules but challenges students to launch their own language investigation, enlarging their professional scope and contributing to the development of their general and linguistic competences. The background for the pedagogical experiment was the need for a shift in the teacher–student model of interaction. To prove the benefits of semi-independent student’s research, the article covers four research cases performed by 3rd year students at Moscow State Linguistic University under the guidance of their English grammar lecturers. While working at their respective tasks, the students tried their hand at a proper piece of scientific study and mastered their skills at a new research instrument. Corpus data obtained, they worked in cooperation with their lecturers to arrive at conclusions reviving textbook materials. Thus, the rules and tendencies verified were no longer offered to the class as ready-made answers. The results of the experiment foreground the positive effect of students’ getting access to novel technologies transforming the traditional roles assigned in class.
Eco-friendly and Economical Spectrophotometric Estimation of the Low Water-Soluble Drug (Norfloxacin) Applying the Concept of Mixed Hydrotropy
Authors: Soni Ketan , Sharma Kavita
Published: December 2021

Objectives The main aim of the research was to analyze an economical and eco-friendly approach to improve the solubility of norfloxacin. The current analysis was to utilize the hydrotropic solutions to extract the drugs from their dosage forms, avoiding the use of costlier and harmful organic solvents.

Materials and Methods In this study, an ultraviolet–visible spectrophotometer (model 1800, Shimadzu Corporation) was used to analyze the norfloxacin drug. The mixed hydrotropy approach was used to determine the solubility of norfloxacin. In this work, a blend solution (20% of urea + 20% of sodium benzoate) was used as a hydrotropic solubilizing agent.

Results The solubility of norfloxacin drug in water was very low at ∼0.88 mg/mL and the solubility of norfloxacin drug in the blend solution was 11 mg/mL. From 98.96 (tablet II) to 99.35 (tablet I), the percent estimation value was achieved. This value was nearly 100, so the proposed method was correct. Standard deviation (0.2540–0.4156), percentage coefficient of variation (0.2566–0.4183), and the value of standard error (0.1481–0.2415) are also very low; hence, we can say that the proposed method is accurate.

Conclusion To avoid the use of organic solvents, the mixed hydrotropy concept can be used for spectrophotometric estimation of low water-soluble drugs from bulk drug samples. It provides an economical and environmentally friendly mechanism.
The Hassan Neonatal Morbidity Composite Scale and Neonatal Length of Stay—A Validation Study
Authors: Patil Avinash S. , Grotegut Chad A. , Smith P. Brian , Clark Reese H. , Greenberg Rachel G.
Published: December 2021

Objective Obstetric studies often report neonatal morbidity as a composite score. Composite scores can simplify data analysis when multiple outcomes of interest are present and allows researchers to conduct smaller, more manageable trials. The Hassan scale is a neonatal morbidity composite scale that assigns high scores to infants with multiple morbidities and low scores to infants without or with single morbidities. The objective of this study was to validate the association between scores on the Hassan scale and neonatal intensive care unit (NICU) length of stay

Study Design We conducted a cohort study of all infants born between 22 and 366/7 weeks' gestation and cared for within 419 neonatal units in the Pediatrix Medical Group between 1997 and 2018. Each infant was assigned a Hassan's score based on the number of neonatal morbidity events that occurred during the delivery hospitalization. The association between Hassan's scores and neonatal length of stay was evaluated using linear regression. Multivariable models were constructed to determine if the Hassan score was independently associated with neonatal length of stay.

Results There were 760,037 infants included. The median (interquartile range [IQR]) gestational age of delivery was 34 (31, 35) weeks and the median (IQR) birth weight at delivery was 2,000 (1,503, 2,430) g. The median length of stay for infants discharged home was 17 (10–33) days. A Hassan's score was able to be assigned to 699,206 (92%) patients. Neonatal morbidities included in the Hassan scale were more common among infants born earlier in gestation. On adjusted analysis, the Hassan scale was found to be independently associated with neonatal length of stay (p < 0.001, coefficient = 10.4 days [95% confidence interval (CI): 10.3, 10.4 days]) with higher scores associated with longer lengths of stay.

Conclusion The Hassan scale, more than a binary composite score, is able to differentiate preterm infants with prolonged hospitalizations from those with short hospitalizations.

Key Points
Incidence and Risk Factors for Postpartum Depression among Women with Preterm Prelabor Rupture of Membranes
Authors: Zemtsov Gregory E. , Avram Carmen M. , Darling Alice , Dillon Jacquelyn , Wheeler Sarahn , Dotters-Katz Sarah K.
Published: December 2021

Objective Patients admitted for preterm prelabor rupture of membranes are more likely to have risk factors for postpartum depression, including preterm delivery, low-birthweight infants, and a stressful life event. However, there is a paucity of data characterizing the development of postpartum depression in this population. We aim to evaluate the incidence of and describe risk factors for postpartum depression among patients admitted with preterm prelabor rupture of membranes.

Study Design This is a retrospective cohort study of patients admitted for preterm prelabor rupture of membranes in a single health system between 2013 and 2019. Patients who developed depression were compared with patients who did not develop depression. Demographic, antepartum/intrapartum/postpartum, and neonatal characteristics were compared. Bivariate statistics were used to compare outcomes and logistic regression was used to estimate adjusted odds ratios.

Results Of 132 included patients with preterm prelabor rupture of membranes, 25 (18.9%) had postpartum depression. Factors significantly (p < 0.05) associated with postpartum depression included history of depression, anxiety, or any prior mental health condition. Earlier admission gestational age, rupture of membranes < 28 weeks, earlier delivery gestational age, neonatal morbidity, and neonatal necrotizing enterocolitis also were significantly associated with postpartum depression. Latency, maternal postpartum length of stay, and neonatal intensive care unit length of stay were not significantly associated. In regression models, only a history of depression (odds ratio [OR], 11.89; 95% confidence interval [CI], 2.78–50.95) and neonatal morbidity (OR, 5.01; 95% CI, 1.15–21.89) remained associated with postpartum depression.

Conclusion Postpartum depression occurred in nearly one in five patients with preterm prelabor rupture of membranes. Pre-existing depression and adverse neonatal outcomes strongly predicted postpartum depression. There is an urgent need to prioritize maternal mental health among patients with preterm prelabor rupture of membranes in the peripartum period. Further research is needed to identify optimal resources for mitigating the risk of postpartum depression in this cohort.

Key Points
Directly Measured Costs of Severe Maternal Morbidity Events during Delivery Admission Compared with Uncomplicated Deliveries
Authors: Debbink Michelle P. , Metz Torri D. , Nelson Richard E. , Janes Sophie E. , Kroes Alexandra , Begaye Lori J. , Heuser Cara C. , Smid Marcela C. , Silver Robert M. , Varner Michael W. , Einerson Brett D.
Published: December 2021

Objective To estimate the actual excess costs of care for delivery admissions complicated by severe maternal morbidity (SMM) compared with uncomplicated deliveries.

Study Design This is a retrospective cohort study of all deliveries between October 2015 and September 2018 at a single tertiary academic center. Pregnant individuals ≥ 20 weeks' gestation who delivered during a hospital admission (i.e., a “delivery admission”) were included. The primary exposure was SMM, as defined by Centers for Disease Control and Prevention (CDC) criteria, CDC criteria excluding blood transfusion, or by validated hospital-defined criteria (intensive care unit admission or ≥ 4 units of blood products). Potential SMM events identified via administrative and blood bank data were reviewed to confirm SMM events had occurred. Primary outcome was total actual costs of delivery admission derived from time-based accounting and acquisition costs in the institutional Value Driven Outcomes database. Cost of delivery admissions with SMM events was compared with the cost of uncomplicated delivery using adjusted generalized linear models, with separate models for each of the SMM definitions. Relative cost differences are reported due to data restrictions.

Results Of 12,367 eligible individuals, 12,361 had complete cost data. Two hundred and eighty individuals (2.3%) had confirmed SMM events meeting CDC criteria. CDC criteria excluding transfusion alone occurred in 1.0% (n = 121) and hospital-defined SMM in 0.6% (n = 76). In adjusted models, SMM events by CDC criteria were associated with a relative cost increase of 2.45 times (95% confidence interval [CI]: 2.29–2.61) the cost of an uncomplicated delivery. SMM by CDC criteria excluding transfusion alone was associated with a relative increase of 3.26 (95% CI: 2.95–3.60) and hospital-defined SMM with a 4.19-fold (95% CI: 3.64–4.83) increase. Each additional CDC subcategory of SMM diagnoses conferred a relative cost increase of 1.60 (95% CI: 1.43–1.79).

Conclusion SMM is associated with between 2.5- and 4-fold higher cost than uncomplicated deliveries.

Key Points
Machine learning method puts the “super” in super-resolution spectroscopy
Authors: Lim Alane
Published: December 2021

Deep learning network improves feature resolution of infrared imaging method twofold.
Cobalt content dependences of cationic distribution and local fields in CoxFe3−xO4—Hyperfine interaction studies
Authors: Sato W. , Takenaka S. , Sakaguchi M. , Shimada M.
Published: December 2021

Co content (x) dependences of cationic distribution and local fields at the tetrahedral A-site and octahedral B-site nuclei in Co ferrites, CoxFe3−xO4 (x = 0–1.0), were investigated by means of hyperfine interaction techniques. A combined investigation by 57Fe transmission and 57Co emission Mössbauer spectroscopies revealed that about 6% of Co2+ ions occupy the A sites for the sample with Co contents of x = 0 and 1.0. This observation evidently suggests that the site selectivity of Co2+ ions is independent of x for samples prepared on the same heat treatment condition. For hyperfine interaction parameters, obvious x dependence was observed for the B-site Fe nuclei, reflecting variation of the atomic ratio of Fe3+/Fe2+ changing with x, whereas for the A-site Fe nuclei, the parameters hardly change along with x. Contrary to the x-independence for the A-site Fe nuclei, however, it was demonstrated by perturbed angular correlation spectroscopy with the nonmagnetic probe 111Cd(←111In) that the hyperfine field at the A site significantly changes along with x. These contradictory results on the A-site fields verify that the nonmagnetic probe can distinguish a subtle change in the local fields with higher sensitivity.
Proton dynamics in water confined at the interface of the graphene–MXene heterostructure
Authors: Xu Lihua , Jiang De-en
Published: December 2021

Heterostructures of 2D materials offer a fertile ground to study ion transport and charge storage. Here, we use ab initio molecular dynamics to examine the proton-transfer/diffusion and redox behavior in a water layer confined in the graphene-Ti3C2O2 heterostructure. We find that in comparison with the similar interface of water confined between Ti3C2O2 layers, the proton redox rate in the dissimilar interface of graphene-Ti3C2O2 is much higher, owing to the very different interfacial structure as well as the interfacial electric field induced by an electron transfer in the latter. Water molecules in the dissimilar interface of the graphene-Ti3C2O2 heterostructure form a denser hydrogen-bond network with a preferred orientation of water molecules, leading to an increase in proton mobility with proton concentration in the graphene-Ti3C2O2 interface. As the proton concentration further increases, proton mobility decreases due to increasingly more frequent surface redox events that slow down proton mobility due to binding with surface O atoms. Our work provides important insights into how the dissimilar interface and their associated interfacial structure and properties impact proton transfer and redox in the confined space.
On the method of determining instantaneous wall shear stress from near-wall velocity measurements in wall turbulence
Authors: Chen Qigang , Duan Yanchong , Zhong Qiang , Wang Zhongxiang , Huang Lei
Published: December 2021

The determination of the instantaneous wall shear stress (WSS) from near-wall velocity measurements has received considerable attention. However, the most appropriate procedure and the achievable accuracy remain open topics. The present work uses direct numerical simulation datasets of channel flow to investigate the influences of the wall-normal distribution of instantaneous velocity, the method for estimating the velocity gradient, and the wall-normal position of velocity vectors on the accuracy of the instantaneous WSS determined from near-wall velocity measurements. In general, the method of dividing instantaneous velocity vectors by their wall-normal positions performs better than the method of linearly fitting instantaneous velocity profiles for estimating the wall velocity gradients when the wall position is correctly determined. However, the nonlinear instantaneous velocity distribution within the viscous layer means that all methods introduce a negative mean bias error and non-negligible root mean square error for the instantaneous WSS and its statistics. The magnitudes of these errors increase with the wall-normal position of the velocity vectors. An empirical method for correcting the instantaneous WSS statistics is proposed based on the negligible Reynolds number dependence of the bias error of all statistics. The influence of the wall-normal position of the velocity vectors on the WSS statistics and the correction method are verified using experimental data from open channel flows. The verification results show that the correction method significantly improves the accuracy of the statistics of instantaneous WSS determined from near-wall velocity measurements under canonical wall turbulence.
Understanding the phase transformation mechanisms that affect the dynamic response of Fe-based microstructures at the atomic scales
Authors: Mishra Avanish , Lind Jonathan , Kumar Mukul , Dongare Avinash M.
Published: December 2021

Large-scale molecular dynamics (MD) simulations were carried out to investigate the shock-induced evolution of microstructure in Fe-based systems comprising single-crystal and layered Cu/Fe alloys with a distribution of interfaces. The shock compression of pure single-crystal Fe oriented along [110] above a threshold pressure results in a BCC (α) → HCP (ɛ) phase transformation behavior that generates a distribution of ε phase variants in the phase transformed region of the microstructure behind the shock front. The propagation of the release wave through a phase transformed ε phase causes a reverse ɛ → α phase transformation and renders a distribution of twins for the [110] oriented Fe that serve as void nucleation sites during spall failure. The simulations reveal that the α → ɛ → α transformation-induced twinning for shock loading along the [110] direction is due to a dominant ɛ phase variant formed during compression that rotates on the arrival of the release wave followed by a reverse phase transformation to twins in the α phase. The modifications in the evolution of the ɛ phase variants and twins in Fe behavior are also studied for Cu–Fe layered microstructures due to the shock wave interactions with the Cu/Fe interfaces using a newly constructed Cu–Fe alloy potential. The MD simulations suggest that interfaces affect the observed variants during shock compression and, hence, distributions of twins during shock release that affects the void nucleation stresses in the Fe phase of Cu/Fe microstructures.
A method for long-time integration of Lyapunov exponent and vectors along fluid particle trajectories
Authors: Cui Zhiwen , Zhao Lihao
Published: December 2021

Finite-time Lyapunov exponents (FTLEs) and Lyapunov vectors (LVs) are powerful tools to illustrate Lagrangian coherent structures (LCSs) in experiments and numerical simulations of fluid flows. To obtain the FTLEs and LVs with the flow simulation simultaneously, we computed the eigenvectors and eigenvalues of the left Cauchy–Green tensor along the trajectories of fluid particles separately instead of computing deformation gradient tensor directly. The method proposed in the present study not only avoids solving the eigenvalue problem of the singular matrix at each time step but also guarantees a stable simulation for a long time. The method is applied in the computation of FTLEs and LVs in two-/three-dimensional (2D/3D) compressible/incompressible cases. In 2D cases, we found that LCSs are folded as fine filaments induced by vortices, while LCSs are sheet-like structures among the vortices for 3D cases. Meanwhile, the directions of stretching and compression of LVs are tangent and normal to the FTLE ridges (2D)/iso-surfaces (3D), respectively.
Characteristics of flow past elongated bluff bodies with underbody gaps due to varying inflow turbulence
Authors: Aleyasin Seyed Sobhan , Tachie Mark Francis , Balachandar Ram
Published: December 2021

An experimental study was performed on two elongated bluff bodies with underbody gaps, a square-back Ahmed body and a cuboid, to investigate the effects of geometry and the approach flow conditions on the time-averaged and temporal characteristics. The flow fields produced from two approach turbulent boundary layers with moderate (∼4%) and high (∼7%) turbulence levels were studied using time-resolved and double-frame particle image velocimetry systems. With the moderate turbulence, the wake topology and the loci of the centroid of vortices exhibit the well-known toroidal structure behind the Ahmed body, though it is skewed away from the wall. Also, the regions of elevated Reynolds stresses are considerably larger in the upper shear layer compared to the lower shear layer due to the reduced underbody velocity. The dominant frequencies obtained from the velocity fluctuations, reverse flow area, and the coefficient of the first proper orthogonal decomposition (POD) mode are identical. The flow structures are more complex behind the cuboid and the Ahmed body mounted in the high turbulent flow due to the enhanced interaction between the lower and upper shear layers, which is also evident from the shape of the turbulent structures in these shear layers. Consequently, the dominant vortex shedding frequencies varied as the streamwise distance from the bodies increased. The probability density function of the reverse flow area and the POD analysis performed in the spanwise plane revealed that the bi-stability phenomenon is absent in the present study due to the significant modification of the wake topology.
Resistive-switching and memory in halide perovskite nanoparticles through a corona-poling approach: Necessity of type-I core–shell structures
Authors: Bera Arpan , Ganguly Rini , Chakraborty Raja , Pal Amlan J.
Published: December 2021

We show a resistive-switching and associated memory phenomenon in core–shell nanostructures of halide perovskites, namely, CsPbCl3 in the core and Cs4PbCl6 as a shell layer. We have employed the corona poling technique to approach a carrier-tunneling process as a non-contact and localized mode of measurement while achieving the switching phenomenon; such measurements with a scanning tunneling microscope tip forbade filament-formation, which commonly yields a low-resistive state during a resistive-switching. Interestingly, nanoparticles of core–shell components, such as CsPbCl3 and Cs4PbCl6, did not result in resistive-switching even in wider experimental conditions. Scanning tunneling spectroscopy of CsPbCl3 and Cs4PbCl6 nanoparticles and of core–shell nanostructures evidenced a type-I band-alignment at the core-to-shell interface. We have discussed the occurrence of resistive-switching, which results in a memory phenomenon as well in terms of charge-confinements in the type-I energy architecture of core–shell nanoparticles. The results thereby substantiate the necessity of such a type-I band-alignment in yielding a resistive-switching without filament formation.
Proposal for chip-scale generation and verification of photonic dimers
Authors: Kim Juhyeon , Mastropietro Donato , Steel Duncan , Shen Jung-Tsung , Ku Pei-Cheng
Published: December 2021

A semiconductor chip to generate photonic dimers, a quantum photonic state, is proposed and analyzed. The measurement scheme to validate the existence of dimers is also discussed. The design uses InAs epitaxial quantum dot structures coupled to weak laser pulses with the interaction tailored by a chiral nanophotonic waveguide. The performance is analyzed as a function of quantum dot misalignment. Greater than 50% excitation efficiency is still expected as long as the quantum dot is in the lower half of the chiral waveguide.
High-fidelity simulation of a hydraulic jump around a surface-piercing hydrofoil
Authors: Li Zheng , Liu Cheng , Wan Decheng , Hu Changhong
Published: December 2021

For a surface-piercing hydrofoil traveling at high speed, a turbulent hydraulic jump may arise at the intersection of the body with the free surface. This hydrodynamic phenomenon involves violent wave breaking, bringing great challenges for experimental analysis. In this work, a high-fidelity large eddy simulation is performed to study the turbulent air-entraining flow near foil. One advantage of the present simulation is that a quantitative analysis can be implemented even in the turbulent two-phase mixing region containing a large amount of entrained air, which is difficult for traditional experimental and theoretical approaches. We employ a conservative coupled level set/volume-of-fluid scheme to capture the free surface. A highly robust scheme is introduced to guarantee stability in simulating large density ratio two-phase flows. The present method is implemented based on a block-structured adaptive mesh, by which the efficiency of the high-fidelity simulation can be improved. The main flow features of the wedge-shaped hydraulic jump, including the wave patterns, free surface elevation, and frequency spectra, are compared with experimental data. We find that the flow structures show clear differences from those found in the canonical hydraulic jump, owing to the presence of the foil surface. Shoulder wave breaking starts at the trough of the mid-body, develops in a wedge shape, depends strongly on Froude number, and is responsible for most of the large-scale air entrainment. The properties of the turbulent hydraulic jump and some of the key quantities characterizing the air-entraining flow, including the spatial distribution of the bubble cloud, the void fraction, and the bubble/droplet size spectrum, are fully investigated for typical Froude numbers.
Flow over a hydrofoil at incidence immersed within the wake of a propeller
Authors: Posa A. , Broglia R.
Published: December 2021

The flow over a hydrofoil in the wake of a marine propeller is studied using large-eddy simulation on a cylindrical grid composed of 3.8 billion points. Four angles of incidence of the downstream hydrofoil are considered, ranging from 0° to 15°. The impact of the propeller wake on the flow within the boundary layer of the hydrofoil is substantial, increasing the skin-friction and producing significant spanwise flows, associated especially with the deflection of the tip and hub vortices. This deflection is strongly influenced by the incidence angle of the hydrofoil, producing an overall expansion of the propeller wake on its pressure side and a contraction on its suction side. The tip and hub vortices are also the major source of pressure fluctuations on the surface of the hydrofoil, affecting this way its unsteady lift and drag coefficients. On the pressure side, the most significant pressure fluctuations are due to the hub vortex, while on the suction side, their maxima originate from the overlapping effects by the tip vortices and the adverse streamwise pressure gradient, promoting the instability of the boundary layer. Pressure fluctuations are an increasing function of the incidence of the hydrofoil on both its pressure and suction sides.
Munc18-dependent and -independent clustering of syntaxin in the plasma membrane of cultured endocrine cells
Authors: Wan Lei , Chen Xi , Almers Wolfhard
Published: December 2021

Significance

For exocytosis, a secretory granule recruits three proteins associated with the plasma membrane, syntaxin, SNAP-25, and Munc18. All three form clusters. In artificial lipid bilayers, nonstoichiometric factors such as bilayer composition, thickness, and curvature cause syntaxin to cluster even when it contains little more than its transmembrane domain. We have also observed such clusters in live cells. Where single granules had docked at the plasma membrane, they recruited complexes of syntaxin and Munc18-1 into densely packed clusters. The clusters may impede fusion but are well suited to keep granules anchored at the plasma membrane.
Measuring the buffering capacity of gene silencing in
Saccharomyces cerevisiae
Authors: Wu Kenneth , Dhillon Namrita , Du Kelvin , Kamakaka Rohinton T.
Published: December 2021

Significance

Gene silencing, once established, is stably maintained for several generations. Despite the high fidelity of the inheritance of the silent state, individual components of silenced chromatin are in constant flux. Models suggest that silent loci can tolerate fluctuations in Sir proteins and histone acetylation levels, but the level of tolerance is unknown. To understand the quantitative relationships between H4K16 acetylation, Sir proteins, and silencing, we developed assays to quantitatively alter a H4K16 acetylation mimic allele and Sir protein levels and measure the effects of these changes on silencing. Our data suggest that a two- to threefold change in levels of histone marks and specific Sir proteins affects the stability of the silent state of a large chromatin domain.
Stable sodium-sulfur electrochemistry enabled by phosphorus-based complexation
Authors: Wang Chuanlong , Zhang Yue , Zhang Yiwen , Luo Jianmin , Hu Xiaofei , Matios Edward , Crane Jackson , Xu Rui , Wang Hai , Li Weiyang
Published: December 2021

Significance

Beyond lithium-ion technologies, sodium-sulfur batteries stand out because of their multielectron redox reactions and high theoretical specific energy (1,274 Wh per kg of sulfur). They hold the potential of overcoming the capacity limitation of intercalation-based chemistry (<400 Wh kg
−1
). Major challenges in realizing this potential lie in the formation of undesirable intermediates, irreversible precipitation of solid products, and hence, poor battery cycle life. This work presents a series of sodium phosphorothioate complexes that show superior battery performance at ambient and reduced temperatures. They offer great promise for enabling sodium-based energy storage systems with wide-ranging temperature operability. The coupled experimental characterization and theoretical analysis are valuable for guiding complex synthesis, experimental design, and data interpretation.