bluuebunny/crossref_metadata_2025 huggingface dataset:
Association of Mean Platelet Volume with Risk Factors and Functional Outcome in Acute Ischemic Stroke
Authors: OT Sreejith , Zafar Lubna , Beg Mujahid , Siddiqui Obaid Ahmed
Published: September 2021

Background Stroke is the second leading cause of death in the world and a major cause of disability, with ischemic stroke contributing to 87% of all strokes. Platelets are central in the formation of thrombus, and in the process, they enlarge in size, become active, and secrete prothrombotic factors. This is supported by the presence of large platelets in ischemic stroke, where they may be implicated in the pathogenesis of vessel occlusion, leading to stroke. The mean platelet volume (MPV) is an important laboratory marker of platelet function and activation.

Materials and Methods The present study was conducted to assess the role of MPV in the pathogenesis, severity, and outcome of ischemic stroke. It was an observational study in 100 acute ischemic stroke (AIS) patients (excluding cardioembolic stroke) admitted to the Medicine wards, Department of Medicine, Jawaharlal Nehru Medical College, a tertiary care hospital at Aligarh. The MPV was correlated with the conventional risk factors of ischemic stroke and outcome (using modified Rankin scale [mRS]). The study revealed statistically significant correlation between MPV and hypertension, type 2 diabetes mellitus, and carotid intima media thickness (CIMT). Also, the MPV at presentation positively correlated with mRS (correlation coefficient 0.818); thus, high MPV was associated with more severe disability.

Conclusion The MPV at the time of presentation of ischemic stroke may be useful in predicting the severity of stroke and neurological recovery. However, a larger study including diverse population is required to endorse its predictive value in AIS.
Etiological and Radiological Spectrum of Longitudinal Myelitis: A Hospital-Based Study in North East India
Authors: Synmon Baiakmenlang , Phukan Pranjal , Sharma Shri Ram , Hussain Mussaraf
Published: September 2021

Introduction An inflammatory lesion of the spinal cord where three or more than three vertebral segments of the cord is involved is called longitudinal extensive myelitis (LETM). It has several varied causes out of which neuromyelitis optica (NMO) and its spectrum disorder have received a distinct entity. Various radiological and clinical features help us to suspect an etiology which then further guides us into the treatment protocol and prognosis of the patients.

Materials and Methods A retrospective study performed in a referral center in North East India in 15 months. Thirty-two patients of LETM were enrolled based on clinical and radiological available data. An attempt was made to classify the various etiologies and correlate with their radiological findings.

Results The most common etiology noted was NMO seen in 7 patients (21.8%) followed by tuberculosis (TB) (18.7%) and post-infection myelitis (18.7%). Other etiology seen was acute disseminated encephalomyelitis (6.24%), spinal cord infarct (3.12%), radiation myelitis (6.24%), Japanese encephalitis sequalae (3.12%), systemic lupus erythematosus (3.12%), and remained undiagnosed in six patients (18.7%). Radiologically, cervico-dorsal spine was most common location in NMO (71%) whereas dorsolumbar in TB (50%). The lesion was predominantly central in both NMO (100%) and TB (80%) as compared with the other causes of LETM. It was noted that more than 50% of the transverse area of the cord was involved in both NMO (71%) and TB (50%), but < 50% involvement were more common in the post-infectious and others causes of LETM.

Conclusion LETM has a various differential diagnosis, infection need to be kept in mind while ruling out NMO. Radiological features can suggest or help differentiate the various etiologies of LETM but NMO and infection like TB almost has the same features except for a different cord site predilection.
Head and Neck Free Flap Reconstruction in an Academic versus a Community Setting
Authors: Lewcun Joseph , Massand Sameer , Trangucci John , Shen Chan , Johnson Timothy S.
Published: September 2021

Background Head and neck free flap reconstructions are complex procedures requiring extensive resources, and have the potential to be highly morbid. As such, it is imperative that they should be performed in an appropriate setting, optimizing outcomes while limiting morbidity. The aim of this study is to identify any disparities in the treatment outcomes of patients undergoing head and neck free flap reconstruction by a single surgeon in an academic versus a community hospital setting.

Methods A retrospective review of all patients who underwent head and neck free flap reconstruction for any indication by a single surgeon from 2009 to 2019 was conducted. All surgeries were performed at one of two hospitals: one academic medical center and one community hospital. Demographics and rates of partial or complete flap failure, medical complications, surgical complications, mortality, and other secondary outcomes were compared between the two settings.

Results Ninety-two patients who underwent head and neck free flap reconstruction were included. Fifty-seven (62%) of free flap reconstructions were performed in the academic medical center, while 35 (38%) were performed in the community hospital. There were no significant differences in complete flap loss, either intraoperative or postoperative (p = 0.5060), partial flap loss (p = 0.5827), postoperative surgical complications (p = 0.2930), or medical complications (p = 0.7960) between groups. The in-hospital mortality rate was 0% (n = 0) at the university hospital as compared with 5.7% at the community hospital (p = 0.0681). The mean operative time was 702.3 minutes at the university hospital and 606.3 minutes at the community hospital (p = 0.0080).

Conclusion Head and neck free flap surgery can be performed safely in either an academic or a community setting, with no difference in primary outcomes of surgery. Preferential selection of either treatment setting should be based on consideration of patient needs and availability of auxiliary specialty services.
Extended Cranial Ultrasound Views in Infants with Acute Brain Stem/Infratentorial Lesions: Diagnosis of a Progressive Midline Glioma in a 6-Week-Old Infant
Authors: Lange Matthias , Mitzlaff Bernd , Beske Florian , Koester Holger , Aumann Wiebke , Woitzik Johannes , Mueller Hermann L. , Heep Axel
Published: September 2021

Central nervous system (CNS) tumors are the most common solid tumors in children and adolescents. However, in neonates and children aged younger than a year, they are very rare. Clinical presentation in neonates is often subtle and nonspecific. When neurological symptoms are apparent at this age, cranial ultrasound (CUS) is often done as the initial evaluation, with a standard approach through the anterior fontanel (AF), followed by further imaging, such as magnetic resonance imaging (MRI), if necessary. We report the first neonatal case of a rapidly progressive diffuse midline glioma positive for histone H3 K27M mutation (World Health Organization [WHO] grade IV) in which using extended (transmastoid) CUS studies through the mastoid fontanelle (MF) in the second month of life defined the lesion in the brainstem.
Reclaiming agency: skills, academics and students in the Social Sciences
Authors: David Maxine , Maurer Heidi
Published: September 2021

The adoption of active learning pedagogy and, later, the institution of the employability agenda in Higher Education have resulted in a severe loss of agency for academics and students in the Social Sciences. In this article, we reflect on our experiences of applying active learning methods. We argue that we have been part of a change that has occasioned a loss of key skills development, especially those associated with traditional learning and academic thinking. An overly headlong rush to implement the “new” over the “old” saw the discarding of certain skills central to the active learning agenda. Further, the emphasis on student satisfaction, professionalisation and quality assurance pushed the academic to the sidelines, to the detriment of Higher Education. We, therefore, first critique the skills debate and identify shortcomings in the active learning application that emerged from that debate. We focus on the skills emphasised in practice, how they are portrayed in opposition (instead of complementarity) to academic skills, and how they undermine the agency academics and students really require. Next, we propose a reconsideration of necessary but undervalued skills like reading, listening and note-taking.
Barium titanate-based thermistors: Past achievements, state of the art, and future perspectives
Authors: Bell Jon G. , Graule Thomas , Stuer Michael
Published: September 2021

Barium titanate materials displaying a positive temperature coefficient of resistivity are ubiquitously employed as thermistors in electrical current and voltage control systems, as well as in gas and thermal sensing applications. The positive temperature coefficient of resistivity effect is widely accepted to be a grain boundary-based phenomenon, although detailed studies on grain boundary structure and chemistry, and their influence on the resulting electrical properties, are seriously lacking. Tailoring of the positive temperature coefficient of resistivity electrical characteristics, for specific high-value applications, will require improved understanding and control over grain boundary phenomenon. A comprehensive overview of the development of barium titanate-based positive temperature coefficient of resistivity ceramics is initially presented. We then advance to a discussion on emerging grain boundary characterization techniques, specifically, a stereographic analysis of electron backscatter diffraction data that could assist in enhancing control over BaTiO3 defect chemistry and microstructure, through characterization and subsequent manipulation of the population of grain boundary types. These techniques have great potential for increasing the understanding of the delicate interplay between processing conditions, chemistry, microstructure, and functional electrical properties, and are relevant to the development of advanced, high-performance ceramics and electroceramics in general. Contemporary advancements in the field, such as lead-free positive temperature coefficient of resistivity effect materials and multilayer miniaturized systems based on hypostoichiometric barium compositions, are reviewed. Finally, perspectives on future lines of thermistor research, with a focus on the energy sector, are presented including applications in gas separation and chemical sensing.
Unified potential fluctuations model for photoluminescence spectra at room temperature—Cu(In,Ga)Se2 thin films
Authors: Spaans E. M. , de Wild J. , Savenije T. J. , Vermang B.
Published: September 2021

Room temperature photoluminescence (PL) is a powerful technique to study the properties of semiconductors. However, the interpretation of the data can be cumbersome when non-ideal band edge absorption takes place, as is the case in the presence of potential fluctuations. In this study, PL measurements are modeled to quantify potential fluctuations in Cu(In,Ga)Se2 (CIGS) absorber layers for photovoltaic applications. Previous models have attributed these variations to either bandgap fluctuations (BGFs) or electrostatic fluctuations (EFs). In reality, these two phenomena happen simultaneously and, therefore, affect the PL together. For this, the unified potential fluctuation (UPF) model is introduced. This model incorporates the effect of both types of fluctuations on the absorptance of the material and subsequently the PL spectra. The UPF model is successfully used to fit both single- and three-stage co-evaporated ultrathin (around 500 nm) CIGS samples, showing a clear improvement with respect to the previous BGF and EF models. Some PL measurements show possible interference distortions for which an interference function is used to simultaneously correct the PL spectra of a sample measured with several laser excitation intensities. All the models used in this work are bundled into a user-friendly, open-source Python program.
Oblique angle deposition of boron carbide films by magnetron sputtering
Authors: Shin S. J. , Bayu Aji L. B. , Bae J. H. , Engwall A. M. , Nielsen M. H. , Hammons J. A. , Zuo X. B. , Lee B. , Lepro X. , Mirkarimi P. B. , Kucheyev S. O.
Published: September 2021

Many applications of boron carbide (B4C) films entail deposition on non-planar substrates, necessitating a better understanding of oblique angle deposition phenomena. Here, we systematically study the effect of substrate tilt on properties of B4C films with thicknesses up to 10 μm deposited by direct current magnetron sputtering. Results show that all films are amorphous and columnar with an average column width of ∼100 nm, independent of substrate tilt. Column tilt angles are limited to ∼20° even for substrate tilt of 80°. Film density, residual stress, and the refractive index weakly (within ≲20%) depend on substrate tilt. Oxygen impurities bond preferentially with carbon atoms in inter-columnar regions. Substrate tilt has a major effect on mechanical properties that decrease by ∼50%, suggesting weak interconnection between nano-columns. Implications of these observations for the deposition onto non-planar substrates are discussed.
Synchronized clusters in globally connected networks of second-order oscillators: Uncovering the role of inertia
Authors: Gao Jian , Efstathiou Konstantinos
Published: September 2021

We discuss the formation of secondary synchronized clusters, that is, small clusters of synchronized oscillators besides the main cluster, in second-order oscillator networks and the role of inertia in this process. Such secondary synchronized clusters give rise to non-stationary states such as oscillatory and standing wave states. After describing the formation of such clusters through numerical simulations, we use a time-periodic mean field ansatz to obtain a qualitative understanding of the formation of non-stationary states. Finally, the effect of inertia in the formation of secondary synchronized clusters is analyzed through a minimal model. The analysis shows that the effect of the main synchronized cluster on the other oscillators is weakened by inertias, thus leading to secondary synchronized clusters during the transition to synchronization.
Approximate universality in the electric field variation on a field-emitter tip in the presence of space charge
Authors: Kumar Raghwendra , Singh Gaurav , Biswas Debabrata
Published: September 2021

The electric field at the surface of a curved emitter is necessary to calculate the field emission current. For smooth parabolic emitting tips where space charge is negligible, variation of the electric field at the surface is known to follow the generalized cosine law. Here, we investigate the validity of the cosine law in the regime, where space charge due to emitted electrons is important. Particle-in-cell (PIC) simulations with an emission algorithm based on the cosine law are employed for this study. It is shown that if EP and EL be the field at the apex of tip with and without space charge, respectively, then for ϑ=EP/EL≥0.9, the average relative deviation of the electric field from the cosine law is less than 3% over the endcap. Thus, an emission scheme based on the cosine law may be used in PIC simulations of field emission of electrons from curved emitter tips in the weak space charge regime. The relation between ϑ and normalized current ζ for curved emitters in this regime is also investigated. A linear relation, ϑ=1−δζ (where δ is a constant), similar to that obtained theoretically for flat emitting surfaces is observed, but the value of δ indicates that the extension of the theory for curved emitters may require incorporation of the field enhancement factor.
Gold and silver nanocomposite-based biostable and biocompatible electronic textile for wearable electromyographic biosensors
Authors: Lim Taehwan , Zhang Huanan , Lee Sohee
Published: September 2021

Wearable biosensors have received significant attention due to the possibility of measuring physiological signals on demand. Particularly, the monitoring of electromyographic (EMG) signals on demand by wearable platforms has significant potential to revolutionize the diagnostics and treatment of neuromuscular diseases and for advancing human–computer interfaces. Electronic textile-based biosensors have several advantages, including the simple scale-up process and the ease of fabricating multiple large area electrodes over the whole body to obtain precise measurements. Hence, the electronic textile production requires an affordable approach to fabricate biocompatible and biostable electronic circuits on textile materials. This work explores the possibility of combining screen printing and electrodeposition techniques to produce a biostable nanocomposite-based EMG biosensor on textile. Screen printing was selected to fabricate conductive fabrics that would ultimately be a highly durable textile-based sensor. Silver paste, including microscale silver flakes, was printed on PET/cotton blended fabrics. However, the microscale silver surface was limited for EMG sensors due to low surface area and toxicity, causing low signal detection performance and skin irritation. Gold nanoparticles (Au NPs) were deposited on silver flakes to address the requirements of high-performance and biocompatible biosensors. We confirmed that the gold functionalization improved electrical and electrochemical performance. In addition, various tests were performed to determine electrochemical and biological stability under physiological conditions. The test results proved that Au NPs have successfully encapsulated the surface of silver flakes, preventing the exposure of the silver to the physiological environment. EMG signal recording was performed to confirm the functionalization effect that improved the signal to noise ratio (SNR) of 12.5 with 120 nm Au NPs. Moreover, EMG sensing from bicep workouts and finger movements showed the high sensitivity of the electronic fabrics. Although the SNR of EMG signals dropped to 7.2 after a 15-time washing test, the stabilized SNR after 5 washing cycles indicated that the Au/Ag biosensors showed washing durability. The study demonstrates that this affordable approach can be considered for large-scale production of wearable EMG biosensors.
Synthesis of fcc-Co from isostructural Co4N
Authors: Seema  , Kumar Dileep , Deshpande U. P. , Gupta Mukul
Published: September 2021

This work demonstrates the synthesis of fcc-Co derived from an isostructural Co4N phase. When deposited at high substrate temperature (Ts) or thermal annealing (Ta) above 573 K, the out-diffusion of N from fcc-Co4N occurs, leaving behind a high purity fcc-Co phase. Generally, Co grows in a hcp structure, and a hcp to fcc-Co transformation can be facilitated at high temperature or pressure. The proposed route by nitridation and diffusion of N not only brings down the transition temperature but an impurity present in the form of hcp-Co can be avoided altogether as well. Oriented Co4N(111) thin films were grown using a CrN(111) template on a quartz substrate using dc magnetron sputtering. Samples were grown at different Ts or room temperature grown Co4N samples were annealed at different Ta. Analysis using x-ray diffraction, N K-edge x-ray absorption, x-ray photoelectron, and secondary ion mass spectroscopy confirmed the formation of fcc-Co4N or fcc-Co phases. Furthermore, it was found that Co–N bonding and N concentration get significantly reduced at high Ts or Ta due to exceptionally high N self-diffusion taking place in Co4N. Magnetic measurements using ex situ and in situ magneto-optical Kerr effect showed differences in saturation behavior and coercivity of Co4N and fcc-Co samples. By combining structural, electronic, and magnetization measurements, it has been observed that a high purity fcc-Co can be conveniently derived from the isostructural Co4N aided by an exceptionally high N self-diffusion in Co4N.
Self-assembling of the neutral intermediate with chemically bound argon in photoexcited van der Waals complex Ar–I2
Authors: Bogomolov Alexandr S. , Dozmorov Nikolay V. , Kochubei Sergei A. , Baklanov Alexey V.
Published: September 2021

Photodissociation of the van der Waals complex Ar–I2 after excitation into the Rydberg states of I2 has been investigated with velocity map imaging of photofragments. Formation of the translationally hot ions of argon Ar+ with three modes in kinetic energy distribution has been revealed. The measured dependence of the kinetic energy of Ar+ on the pumping photon energy indicates the appearance of Ar+ from three channels of the photodissociation of the linear intermediate Ar+–I–I− containing chemically bound argon. These channels are (1) dissociation into Ar++ I2−; (2) three-body dissociation into (Ar+)* + I* + I−, with (Ar+)* and I* being the 2P1/2 states of the species; and (3) two-body electron photodetachment, giving rise to Ar+ + I2 + e. Three indicated channels are similar to those established for the photodissociation of trihalide anions. This similarity confirms the conclusion on the formation of the Ar+–I–I− intermediate, which is isoelectronic to the trihalide anion Cl–I–I−. The mechanism of the Ar+–I–I− formation involves two-photon excitation of the complex Ar–I2 into the Rydberg state of I2 converted into the ion-pair state and further electron transfer from Ar to I+ of the ion-pair state. The self-assembling of the structure making the formation of the Ar+–I–I− intermediate energetically accessible is confirmed by modeling the dynamics in the excited linear complex Ar–I2. Photoexcitation of the van der Waals complexes of noble gases with halogens into the ion-pair states of halogen is supposed to be a promising approach for generating the new chemical compounds of noble gas atoms.
Critical damage degree model of spall fracture in ductile metals
Authors: Zhang Hao , Peng Hui , Pei Xiaoyang , Yao Songlin , He Hongliang , Li Ping
Published: September 2021

A critical damage degree model was established for spall fracture in high-purity ductile polycrystalline metals. Three critical characteristic damage degrees (i.e., nucleation, complete plasticity, and fracture damage) were used to divide the dynamics of damage evolution into four stages: void nucleation, elastoplastic growth, plastic growth, and coalescence. For each stage, a physical model was established based on the damage evolution regularities and mechanism. Simulated results of the proposed model coincided well with the experimental ones in terms of serious spall experiments for oxygen-free copper. Finally, the association between the characteristics of the pullback signal in the spall experiment and the dynamic properties of damage evolution is discussed, indicating that the three critical damage degrees in the model had definite physical meanings.
A seemingly universal particle kinetic distribution in porous media
Authors: Fan Dian , Pini Ronny , Striolo Alberto
Published: September 2021

We study many-particle transport in randomly jammed packing of spheres at different particle Péclet numbers (Pe*). We demonstrate that a modified Nakagami-m function describes particle velocity probability distributions when particle deposition occurs. We assess the universality of said function through comparison against Lagrangian simulations of various particle types as well as experimental data from the literature. We construe the function's physical meaning as its ability to explain particle deposition in terms of Pe* and the competition between distributions of energy barriers for particle release and particles' diffusive energy.
Stability and robustness properties of bioelectric networks: A computational approach
Authors: Grodstein Joel , Levin Michael
Published: September 2021

Morphogenesis during development and regeneration requires cells to communicate and cooperate toward the construction of complex anatomical structures. One important set of mechanisms for coordinating growth and form occurs via developmental bioelectricity—the dynamics of cellular networks driving changes of resting membrane potential which interface with transcriptional and biomechanical downstream cascades. While many molecular details have been elucidated about the instructive processes mediated by ion channel-dependent signaling outside of the nervous system, future advances in regenerative medicine and bioengineering require the understanding of tissue, organ, or whole body-level properties. A key aspect of bioelectric networks is their robustness, which can drive correct, invariant patterning cues despite changing cell number and anatomical configuration of the underlying tissue network. Here, we computationally analyze the minimal models of bioelectric networks and use the example of the regenerating planarian flatworm, to reveal important system-level aspects of bioelectrically derived patterns. These analyses promote an understanding of the robustness of circuits controlling regeneration and suggest design properties that can be exploited for synthetic bioengineering.
The superatomic state beyond conventional magic numbers: Ligated metal chalcogenide superatoms
Authors: Khanna Shiv N. , Reber Arthur C. , Bista Dinesh , Sengupta Turbasu , Lambert Ryan
Published: September 2021

The field of cluster science is drawing increasing attention due to the strong size and composition-dependent properties of clusters and the exciting prospect of clusters serving as the building blocks for materials with tailored properties. However, identifying a unifying central paradigm that provides a framework for classifying and understanding the diverse behaviors is an outstanding challenge. One such central paradigm is the superatom concept that was developed for metallic and ligand-protected metallic clusters. The periodic electronic and geometric closed shells in clusters result in their properties being based on the stability they gain when they achieve closed shells. This stabilization results in the clusters having a well-defined valence, allowing them to be classified as superatoms—thus extending the Periodic Table to a third dimension. This Perspective focuses on extending the superatomic concept to ligated metal–chalcogen clusters that have recently been synthesized in solutions and form assemblies with counterions that have wide-ranging applications. Here, we illustrate that the periodic patterns emerge in the electronic structure of ligated metal-chalcogenide clusters. The stabilization gained by the closing of their electronic shells allows for the prediction of their redox properties. Further investigations reveal how the selection of ligands may control the redox properties of the superatoms. These ligated clusters may serve as chemical dopants for two-dimensional semiconductors to control their transport characteristics. Superatomic molecules of multiple metal–chalcogen superatoms allow for the formation of nano-p–n junctions ideal for directed transport and photon harvesting. This Perspective outlines future developments, including the synthesis of magnetic superatoms.
Gate-controlled quantum dots in monolayer WSe2
Authors: Boddison-Chouinard Justin , Bogan Alex , Fong Norman , Watanabe Kenji , Taniguchi Takashi , Studenikin Sergei , Sachrajda Andrew , Korkusinski Marek , Altintas Abdulmenaf , Bieniek Maciej , Hawrylak Pawel , Luican-Mayer Adina , Gaudreau Louis
Published: September 2021

Quantum confinement and manipulation of charge carriers are critical for achieving devices practical for quantum technologies. The interplay between electron spin and valley, as well as the possibility to address their quantum states electrically and optically, makes two-dimensional (2D) transition metal dichalcogenides an emerging platform for the development of quantum devices. In this work, we fabricate devices based on heterostructures of layered 2D materials, in which we realize gate-controlled tungsten diselenide (WSe2) hole quantum dots. We discuss the observed mesoscopic transport features related to the emergence of quantum dots in the WSe2 device channel, and we compare them to a theoretical model.
Circuits and excitations to enable Brownian token-based computing with skyrmions
Authors: Brems Maarten A. , Kläui Mathias , Virnau Peter
Published: September 2021

Brownian computing exploits thermal motion of discrete signal carriers (tokens) for computations. In this paper, we address two major challenges that hinder competitive realizations of circuits and applications of Brownian token-based computing in actual devices, for instance, based on magnetic skyrmions. To overcome the problem that crossings generate for the fabrication of circuits, we design a crossing-free layout for a composite half-adder module. This layout greatly simplifies experimental implementations as wire crossings are effectively avoided. Additionally, our design is shorter to speed up computations compared to conventional designs. To address the key issue of slow computation based on thermal excitations, we propose to overlay artificial diffusion induced by an external excitation mechanism. For instance, if magnetic skyrmions are used as tokens, artificially induced diffusion by spin–orbit torques or other mechanisms increases the speed of computations by several orders of magnitude. Combined with conventional Brownian computing, the latter could greatly enhance the application scenarios of token-based computing, for example, for low power devices such as autonomous sensors with limited power that is harvested from the environment.
Microrotation viscosity effect on turbulent micropolar fluid channel flow
Authors: Sofiadis G. , Sarris I.
Published: September 2021

Fluids with an internal rigid microstructure, the so-called micropolar fluids, gain significant attention in many industrial, natural, and biological systems. Here, we study in detail the microrotation viscosity effect on turbulent flows by considering an alternative formulation of the Navier–Stokes equation in which the linear and angular momentum is conserved for the fluid and its microstructure, respectively. The case of low-turbulence channel flow with Re = 5600, based on mean velocity, channel height, and the fluid kinematic viscosity, is used to study the effect of polarity. The present results are discussed and compared against the usual channel flow statistics, from Newtonian, dense suspensions with rigid spheres and polymer turbulent flows in similar conditions. It is found that turbulence tends to increase near the wall as micropolar effects get stronger. This enhancement is attributed to a turbulence generation mechanism that seems to be connected with the micropolar stress tensor and is well described by the present model. At the same time, shear stress inclines near the wall, while drag increase is observed throughout the flow regime.
Competing tunneling conduction mechanisms in oxygen deficient Hf0.5Zr0.5O2
Authors: González Yoandris , Hadj Youssef Azza , Dörfler Andreas , Katoch Rajesh , El Mesoudy Abdelouadoud , Sarkissian Andranik , Drouin Dominique , Ruediger Andreas
Published: September 2021

The direct control of the tunneling current as a function of electric polarization in ferroelectric tunnel junctions has recently attracted noticeable attention through the availability of the CMOS compatible ferroelectric hafnium zirconium oxide (Hf0.5Zr0.5O2). While a lot of progress has been made in the understanding of ferroelectric tunnel junctions, the control and optimization of the volume fraction of the polar orthorhombic phase are still in its infancy and raise the question whether all observed resistive switching events are necessarily associated with polarization reversal. Trap-assisted tunneling is also able to modulate the current density through a field-induced variation of the oxygen vacancy density across the tunnel junction. The amplitude of the effect should depend on the pre-existing density of oxygen vacancies introduced during the fabrication. Here, by controlling the oxygen partial pressure during the RF magnetron sputtering deposition of the non-polar monoclinic phase of Hf0.5Zr0.5O2 thin films of approximately 3 nm, we demonstrate tuning of its transport mechanism due to the formation of oxygen vacancies. We show that two mechanisms dominate the current transport depending on the average distance between traps. For large oxygen content in the Hf0.5Zr0.5O2 thin film, direct tunneling (DT) is the dominant transport mechanism, while the electrical conductivity in the oxide can be described by the phonon-assisted tunneling between traps (PATTs) for the oxygen deficient Hf0.5Zr0.5O2 thin film. We derive a critical inter-trap distance and a critical thickness value that explains the transition from DT to PATT mechanism in Hf0.5Zr0.5O2 thin films.
The influence of collision angle for viscous vortex reconnection
Authors: Hu J. , Peterson S. D.
Published: September 2021

We revisit the mechanism of viscous vortex reconnection by considering the collision of vortex rings over a range of initial collision angles and Reynolds numbers. While the overall reconnection process is similar to anti-parallel vortex reconnection, we find that collision angle exerts significant influence over the process, altering the evolution of various global and local quantities. The collision angle primarily manipulates the “pyramid” process, a recently identified stretching mechanism proposed by Moffatt and Kimura [“Towards a finite-time singularity of the Navier-Stokes equations Part 1. Derivation and analysis of dynamical system,” J. Fluid Mech., 861, 930–967 (2019)] to be a potential pathway for finite-time singularity of Euler’s equations, during the approach stage of the rings. However, the “pyramid” process is short-lived for viscous vortices. The present work shows that the “pyramid” process is arrested by parallelization of the colliding vortices, wherein contact of the colliding vortices halts their motion toward each other at the pyramid apex, allowing the rest of the vortex tube to “catch up,” breaking the pyramid structure. Parallelization marks the transition to a second phase of stretching, where the colliding vortices remain parallel. Vorticity amplification from pyramid stretching is significantly stronger than for its parallel counterpart, and is thus the dominant factor determining reconnection properties. Based upon the findings in this study, we conjecture that the parallelization process is the primary mechanism that prevents the finite-time singularity through the pyramid process. Critically, the Reynolds number scaling for the reconnection rate differs depending on the collision angle, which challenges the conjecture of universal Reynolds number scaling in the literature.
M-center in 4H-SiC: Isothermal DLTS and first principles modeling studies
Authors: Capan I. , Brodar T. , Bernat R. , Pastuović Ž. , Makino T. , Ohshima T. , Gouveia J. D. , Coutinho J.
Published: September 2021

We report on a bistable defect known as M-center, here introduced in n-type 4H-SiC by 2 MeV He ion implantation. Deep levels of the M-center are investigated by means of junction spectroscopy techniques, namely, deep level transient spectroscopy (DLTS) and isothermal DLTS. In addition to previously reported three deep levels arising from the M-center (labeled as M1, M2, and M3), we provide direct evidence on the existence of a fourth transition (labeled as M4) with an activation energy of 0.86 eV. Activation energies and apparent capture cross sections for all four metastable defects are determined. From first-principles calculations, it is shown that the observed features of the M-center, including the charge state character, transition levels, bi-stability dynamics, and annealing, are all accounted for by a carbon self-interstitial.
Turbulent radiative diffusion and turbulent Newtonian cooling
Authors: Brandenburg Axel , Das Upasana
Published: September 2021

Radiation transport plays an important role in stellar atmospheres, but the effects of turbulence are being obscured by other effects such as stratification. Using radiative hydrodynamic simulations of forced turbulence, we determine the decay rates of sinusoidal large-scale temperature perturbations of different wavenumbers in the optically thick and thin regimes. Increasing the wavenumber increases the rate of decay in both regimes, but this effect is much weaker than for the usual turbulent diffusion of passive scalars, where the increase is quadratic for small wavenumbers. The turbulent decay is well described by an enhanced Newtonian cooling process in the optically thin limit, which is found to show a weak increase proportional to the square root of the wavenumber. In the optically thick limit, the increase in turbulent decay is somewhat steeper for wavenumbers below the energy-carrying wavenumber of the turbulence, but levels off toward larger wavenumbers. In the presence of turbulence, the typical cooling time is comparable to the turbulent turnover time. We observe that the temperature takes a long time to reach equilibrium in both the optically thin and thick cases, but in the former, the temperature retains smaller scale structures for longer.
Magnetization relaxation and search for the magnetic gap in bulk-insulating V-doped (Bi, Sb)2Te3
Authors: Golias E. , Weschke E. , Flanagan T. , Schierle E. , Richardella A. , Rienks E. D. L. , Mandal P. S. , Varykhalov A. , Sánchez-Barriga J. , Radu F. , Samarth N. , Rader O.
Published: September 2021

V-doped (Bi,Sb)2Te3 has a ten times higher magnetic coercivity than its Cr-doped counterpart and, therefore, is believed to be advantageous for the quantum anomalous Hall effect (QAHE). The QAHE requires the opening of a magnetic bandgap at the Dirac point. We do not find this gap by angle-resolved photoelectron spectroscopy down to 1 K. By x-ray magnetic circular dichroism (XMCD), we directly probe the magnetism at the V site and derive spin and orbital magnetic moments of 1.69 and –0.22 μB/atom. Hysteresis curves of the XMCD signal show a strong dependence of the coercivity on the ramping velocity of the magnetic field. The XMCD signal decays on a timescale of minutes, which we conclude contributes to the absence of a detectable magnetic gap at the Dirac point.
FAD-dependent
C
-glycoside–metabolizing enzymes in microorganisms: Screening, characterization, and crystal structure analysis
Authors: Kumano Takuto , Hori Sanae , Watanabe Satomi , Terashita Yuzu , Yu Hong Yang , Hashimoto Yoshiteru , Senda Toshiya , Senda Miki , Kobayashi Michihiko
Published: September 2021

Significance

Microbial degradation of
C
-glycosides is only reported from human intestinal bacteria. This study isolated a
C
-glycoside–catabolizing bacteria,
Microbacterium
sp. 5-2b, from soil and identified a
C
-glycoside–metabolizing enzyme. Surprisingly, while the metabolic pathway of
C
-glycoside in the strain was similar to that of an intestinal one, the enzyme named CarA catalyzing the initial step of metabolism was completely different from an enzyme identified from the intestinal microorganism; CarA identified as
C
-glycoside 3-oxidase for C-glycoside metabolism exhibited amino acid sequence similarity to pyranose oxidase family proteins. This study clarified the structure, function, and distribution of the enzyme involved in
C
-glycoside catabolism and provides insight into the biogeochemical circulation of
C
-glycosides in nature.
Structural basis for isoform-specific inhibition of human CTPS1
Authors: Lynch Eric M. , DiMattia Michael A. , Albanese Steven , van Zundert Gydo C. P. , Hansen Jesse M. , Quispe Joel D. , Kennedy Madison A. , Verras Andreas , Borrelli Kenneth , Toms Angela V. , Kaila Neelu , Kreutter Kevin D. , McElwee Joshua J. , Kollman Justin M.
Published: September 2021

Significance

An effective immune response depends on the proliferation of T cells, a process that requires the enzyme CTP synthase 1 (CTPS1). Individuals lacking CTPS1 due to a rare genetic disorder exhibit severe immunodeficiencies but lack other major clinical consequences; the requirement for CTP synthase outside of the immune response is met by a second isoform, CTPS2. Inhibiting CTPS1 without affecting CTPS2 is therefore a promising strategy for treating autoimmune disorders and T cell cancers while avoiding off-target effects. We characterize both CTPS1-selective and nonselective inhibitors. Structures of CTPS bound to inhibitors reveal the mechanisms of inhibition and CTPS1 selectivity. Differences in product feedback inhibition between CTPS1 and CTPS2 explain how CTPS1 may sustain enzymatic activity required for T cell proliferation.
History, Discourse, and Policy in Modern Turkey
Authors: Çakmak Alper
Published: September 2021

Through critical discourse analysis (CDA) and the discourse-historical approach (DHA), this book probes into political discourse imbued with historical legacies, with particular focus on explicating the structure and function of AKP stories and its relationship with Turkish politics. It offers an alternative way of reading the transformation in such politics via the pattern of deconstruction, reconstruction, and policymaking. It systematically delineates how President R. Tayyip Erdoğan’s political discourse evokes dialog that embodies the grand legacy of history, deconstructs the mentality of the opposition, reconstructs an alternative dialog, and converts discourse into policy. The book breaks a new ground by introducing a theoretical framework on the relationship between political discourse and policy. It traces how political stories sourced largely by appropriated historical themes and figures enable rhetoricians to weave simple yet good and influential stories to legitimize potential political action, by beguiling people’s hearts and minds.
Presentation followed by negotiation
Authors: Izutsu Katsunobu , Narita Izutsu Mitsuko
Published: September 2021

This study explores the sequential pattern of
sentence- or utterance-final pragmatic particles in Ainu, an
indigenous language of Japan, and demonstrates that the particle
sequences largely exhibit an ordering summarized as presentation
followed by negotiation: a particle concerning the “presentation” of
a speech act is followed by another particle representing the
“negotiation” with the addressee for a speech act. These
“presenting” and “negotiating” functions are further analyzed with
respect to the speech event conception that underlies those
functions.
Verb-based discourse markers in Italian
Authors: Badan Linda
Published: September 2021

This research deals with verb-based discourse
markers in the regional Italian of Veneto: guarda
(te) ‘look you’, vedi (te) ‘see you’.
We show that these markers differ in terms of functions and
syntactic features. We argue that the functions differ depending on
the discourse markers’ syntactic position: some functions can be
realized only in the left periphery, while others can be realized in
both peripheries. When in the left periphery, the discourse markers
express the speaker’s attitude, have their own illocutionary force
and are much more independent from the preceding linguistic context.
Conversely, the discourse markers that can be realized in both
peripheries seem to have a reinforcement and interactional role,
being strictly dependent on the dialogical context.
Emoji as graphic discourse markers
Authors: Wiese Heike , Labrenz Annika
Published: September 2021

We investigate emoji as graphic discourse
markers in German WhatsApp® messages. As comparably novel devices in
the rapidly evolving domain of digital messenging, emoji provide an
interesting example to observe change in progress. We present a
corpus study and an experimental study. Main results are (i) an
overall salience of subjective and intersubjective discourse
meanings for emoji, with (ii) a general advantage for the former,
especially for emoji that iconically include more active elements,
while (iii) dominance relations can be modulated by left- vs.
right-peripheral positions in favor of subjective vs.
intersubjective meanings, respectively. By approaching emoji as
discourse markers, the studies contribute to our understanding of
their pragmatic contribution and provide novel evidence on
positional-functional associations for pragmatic markers.
Functional asymmetry and left-to-right movement
Authors: Bai Yinchun
Published: September 2021

This corpus-based study of the discourse marker
speaking of X addresses the issues of
functional asymmetry and left-to-right movement. It shows that
speaking of X has different pragmatic
functions, which may express different degrees of
(inter)subjectivity in different peripheral positions. But these
functions are not strictly confined to certain peripheries and,
diachronically, there is no statistically significant evidence of
further (inter)subjectification or change in peripheral preferences.
This study thus confirms that the functional asymmetry hypothesis is
better understood as a strong tendency that holds better for certain
functional domains than for others and it serves as a counterexample
to the related left-to-right movement hypothesis therewith.
Literacy histories and talk around texts
Authors: Ávila Reyes Natalia
Published: September 2021

This chapter discusses the value of emic research methods and techniques for studying the academic writing of underrepresented students. In a global context of growing university enrolment, academic writing is seen as one of the main challenges that historically underrepresented students face when admitted to higher education. Studying academic writing in this context calls for a critical stance on language and an emic perspective on research to counteract deficit models that prevail in this kind of research. An ethnographic approach responds to the ontologies and epistemologies needed for this endeavour. Drawing on two research projects, this chapter exemplifies the power of tools such as literacy histories and talk around texts to unveil multiple forms of agency enacted by student writers.
Risk Assessing The Risks: Deliberations On Risk Prioritization
Authors: Sandle Tim
Published: September 2021

One of the dilemmas facing the quality risk management function is with a series of completed risk assessments and a series of multiple outcomes that require addressing, in the context of limited resources. When faced with multiple risks, how are these to be prioritized?
A Risk-Based Revalidation Approach For Medical Devices
Authors: Chen Yeong-Lin
Published: September 2021

This article proposes a risk-based revalidation approach with a simple and pragmatic risk assessment method for mechanical-type medical device manufacturing. Use the risk assessment output in conjunction with initial validation approach as well as product, equipment and process characteristics, a risk-based revalidation approach can be determined. To facilitate the understanding of the determination process, four risk-based revalidation approach case studies are demonstrated.