bluuebunny/crossref_metadata_2025 huggingface dataset:
Historical Perspectives on the Neurologic Manifestations of Viral Pandemics
Authors: Holroyd Kathryn B. , Berkowitz Aaron L.
Published: April 2023

Neurologic symptoms have been reported in over 30% of hospitalized patients with coronavirus disease 2019 (COVID-19), but the pathogenesis of these symptoms remains under investigation. Here, we place the neurologic complications of COVID-19 within the context of three historical viral pandemics that have been associated with neurologic diseases: (1) the 1918 influenza pandemic, subsequent spread of encephalitis lethargica, and lessons for the study of COVID-19-related neuroinflammation; (2) the controversial link between the 1976 influenza vaccination campaign and Guillain–Barré Syndrome and its implications for the post- and parainfectious complications of COVID-19 and COVID-19 vaccination; and (3) potential applications of scientific techniques developed in the wake of the human immunodeficiency virus pandemic to the study of postacute sequelae of COVID-19.
Relationship of the Presence of the Inferior Right Hepatic Vein with the Right Hepatic Vein Diameter and CT Liver Volumetry
Authors: Gündoğdu Elif
Published: April 2023

Background Right hepatic venous anatomy, right lobe volume, and percentage of remnant liver are issues to be considered in preoperative planning especially transplantation.

Objectives The aim of this study was to investigate the relationship of the presence of the inferior right hepatic vein (IRHV) with the right hepatic vein (RHV) diameter, right lobe volume, and percentage of remnant liver.

Materials and Methods In this cross-sectional study, the computed tomography (CT) images of 90 patients who underwent triphasic CT for being living liver donation were evaluated retrospectively. The number and diameter of IRHVs and the diameter of main RHV were recorded. For the liver volume analysis, a deep learning-based automatic liver segmentation (Hepatic VCAR) program was used. A virtual hepatectomy plane was drawn, where the right and left liver volumes were found and the percentage of the left lobe to the total liver volume was calculated. Pearson's correlation analysis was used for correlation analysis and Student's t-test was used to compare parameters.

Results A total of 74 IRHVs were detected in 53 (58.88%) of 90 patients. There were no differences in the percentage of remnant left lobe volume, right lobe volume, and RHV diameter between the IRHV (+) and (−) groups. The RHV diameter had a weak negative correlation with the IRHV diameter, and a weak positive correlation with the right lobe volume.

Conclusions The percentage of remnant left lobe volume, right lobe volume, and RHV diameter did not differ in liver donors with and without an IRHV. The RHV diameter had a weak negative correlation with the IRHV diameter and a weak positive correlation with the right lobe volume.
Postpartum Opioid Prescribing in Patients with Opioid Use Prior to Birth
Authors: Peahl Alex F. , Keer Emma , Hallway Alexander , Kenney Brooke , Waljee Jennifer F. , Townsel Courtney
Published: April 2023

Objective This study aimed to describe opioid prescribing patterns for pregnant patients with a history of or active opioid use to inform postpartum pain management strategies.

Study Design We conducted a retrospective cohort analysis of all patients with a history of opioid use disorder (OUD) or chronic pain seen at a single outpatient clinic specializing in opioid use and OUD in pregnancy from January 2019 to August 2021. Patient characteristics, delivery outcomes, and opioid prescribing information were collected through electronic health record fields. We used descriptive statistics to characterize differences in receipt of an opioid prescription, prescription size, and receipt of a prescription refill across three patient groups: patients with OUD on medication, patients with OUD maintaining abstinence, and patients with chronic pain using opioids. In the study period, the institutional average rate of opioid prescribing after cesarean and vaginal birth were 80.0 and 2.8%, respectively.

Results Of the 69 patients included in this study, 46 (66.7%) had a history of OUD on medication, 14 (20.3%) had a history of OUD maintaining abstinence, and 9 (13.0%) had a history of chronic pain. Receipt of an opioid prescription after childbirth was more common after cesarean birth (12/23, 52.2%) than vaginal birth (3/46, 6.5%). Refills were common in patients who received an opioid proscription (cesarean: 5/12, 41.7%; vaginal: 1/3, 33.3%).

Conclusion Compared with institutional averages, postpartum opioid prescribing rates for people with a history of OUD or chronic pain were 50 to 60% lower for cesarean birth and three times higher for vaginal birth. Future work is needed to balance opioid stewardship and harm reduction with adequate pain control in these high-risk populations.

Key Points
The Subtilisin-Like Protease Furin Regulates Hemin-Dependent Ectodomain Shedding of Glycoprotein VI
Authors: Fink Annalena , Rohlfing Anne-Katrin , Dicenta Valerie , Schaale David , Kremser Marcel , Laspa Zoi , Sigle Manuel , Fu Xiaoqing , Pelzer Andreas , Fischer Melina , Münzer Patrick , Castor Tatsiana , Müller Karin Anne Lydia , Borst Oliver , Lämmerhofer Michael , Gawaz Meinrad Paul
Published: April 2023

Introduction Hemolysis results in release of free hemoglobin and hemin liberation from erythrocytes. Hemin has been described to induce platelet activation and to trigger thrombosis.

Methods We evaluated the effect of hemin on platelet function and surface expression of the platelet collagen receptor glycoprotein VI (GPVI). Isolated platelets were stimulated with increasing concentrations of hemin.

Results We found that hemin strongly enhanced platelet activation, aggregation, and aggregate formation on immobilized collagen under flow. In contrast, we found that surface expression of GPVI was significantly reduced upon hemin stimulation with high hemin concentrations indicating that hemin-induced loss of surface GPVI does not hinder platelet aggregation. Loss of hemin-induced surface expression of GPVI was caused by shedding of the ectodomain of GPVI as verified by immunoblotting and is independent of the GPVI or CLEC-2 mediated ITAM (immunoreceptor-tyrosine-based-activation-motif) signaling pathway as inhibitor studies revealed. Hemin-induced GPVI shedding was independent of metalloproteinases such as ADAM10 or ADAM17, which were previously described to regulate GPVI degradation. Similarly, concentration-dependent shedding of CD62P was also induced by hemin. Unexpectedly, we found that the subtilisin-like proprotein convertase furin controls hemin-dependent GPVI shedding as shown by inhibitor studies using the specific furin inhibitors SSM3 and Hexa-D-arginine. In the presence of SSM3 and Hexa-D-arginine, hemin-associated GPVI degradation was substantially reduced. Further, SSM3 inhibited hemin-induced but not CRP-XL-induced platelet aggregation and thrombus formation, indicating that furin controls specifically hemin-associated platelet functions.

Conclusion In summary, we describe a novel mechanism of hemin-dependent GPVI shedding and platelet function mediated by furin.
Intravenous Thrombolysis or Medical Management for Minor Strokes
Authors: Tu Wen-Jun , Xu Yicheng , Liu Yakun , Li Jilai , Du Jichen , Zhao Jizong
Published: April 2023

Objective To evaluate the outcomes of acute ischemic stroke patients with minor deficits treated with either intravenous thrombolysis (IVT) or routine medical management (MM).

Methods The study included patients with acute ischemic stroke and National Institutes of Health Stroke Scale (NIHSS) scores of 5 or less who were treated with IVT within 4.5 hours from symptom onset and were classified as the IVT group. The MM group consisted of an equal number of patients with minor strokes, matched for sex, age, and severity, who did not receive thrombolysis. Data on patient information were collected for both groups.

Results A total of 26,236 patients were included in this study (13,208 in IVT and 13,208 in MM). Of these patients, 67.9% were men, and the mean age was 67.1 years (standard deviation: 10.9). At 3 months, the IVT group had a higher rate of stroke-independent outcome (Rankin Scale score of 0–2) compared with the MM group (IVT vs. MM: 91.6 vs. 88.6%, absolute difference: 2.5%, 95% confidence interval [CI]: 1.6–3.4%, p = 0.008; adjusted hazard ratio [HR]: 1.2, 95% CI: 1.1–1.4, p = 0.003). Furthermore, there was no significant difference in 3-month mortality rates between the IVT and MM groups (IVT vs. MM: 2.1 vs. 2.5%, absolute difference: −0.6%, 95% CI: −1.1 to 0.3%, p = 0.11; adjusted HR: 0.9, 95% CI: 0.8–1.2, p = 0.09).

Conclusion Compared with MM, IVT does not reduce mortality in minor ischemic stroke but improves functional outcomes in minor stroke with an NIHSS score of 3 to 5.
Adventitial Vasa Vasorum Neovascularization in Femoral Artery of Type 2 Diabetic Patients with Macroangiopathy Is Associated with Macrophages and Lymphocytes as well as the Occurrence of Cardiovascular Events
Authors: Chen Dong , Zhao Zixi , Liu Peng , Liu Xinbang , Wang Xin , Ren Qiuyue , Chang Bai
Published: April 2023

Objectives This study was conducted to assess the relationship between adventitial vasa vasorum neovascularization (VVn) in femoral artery of type 2 diabetic patients with macroangiopathy and the recruitment of macrophages and lymphocytes, and to relate the density of VVn to the occurrence of cardiovascular events.

Materials Femoral artery samples were obtained from amputation cases. A total of 55 type 2 diabetic patients with macroangiopathy, 15 autopsy cases with type 2 diabetes without atherosclerosis.

Methods Hematoxylin and eosin (H&E) staining to observe the histopathological features; Victoria blue staining to analyze the histological features; immunohistochemistry (CD34, CD68, CD20, and CD3) to determine the VVn density and the expression of macrophages, B lymphocytes, and T lymphocytes.

Results Type 2 diabetic patients with macroangiopathy showed a higher mean adventitial VVn density in femoral artery (48.40 ± 9.39 no./mm2) than patients with type 2 diabetes without atherosclerosis (19.75 ± 6.28 no./mm2) (p < 0.01). In addition, the VVn density was positively associated with the expression of CD68 macrophages (r = 0.62, p < 0.01) and CD20 B lymphocytes (r = 0.59, p < 0.01). Type 2 diabetic patients with high VVn density showed more adverse cardiovascular events (27/35 vs. 8/20 events, p = 0.006). In multivariable analysis adjusted for main risk factors for cardiovascular disease, VVn was still independently associated with adverse cardiovascular events (p = 0.01).

Conclusion VVn density in type 2 diabetic patients with macroangiopathy is positively correlated with the adventitial immune-inflammatory cell numbers and the development of atherosclerotic lesions. Furthermore, VVn density is associated with adverse cardiovascular events.
Financial institutions digital transformation: the stages of the journey and business metrics to follow
Authors: Papathomas Aristides , Konteos George
Published: April 2023

This paper examines the stages of the digital transformational path that lies in front of incumbent banks in their conversion into digitally driven institutions and contributes by providing clarity in the parameters that define each stage and the key metrics to be tracked. It is a general review paper, with main tools employed the relevant scholar and grey literature & field observations. The paper identifies three phases for banking institutions’ digital transformation and proceeds with defining the characteristics of the phases and the distinct actions required for an institution to progress through them, employing a set of proposed key tracking indicators. The outcome adds to the, rather limited, academic literature on the subject and can be applied to all relevant banking institutions. Research needs further insides to articulate better the findings and expand them on a cross-examination of relevant theories and approaches. This paper aims at contributing to a growing, contemporary discussion, hopefully assisting in greater collaboration between practitioners and academics.
Antisemitism is predicted by anti-hierarchical aggression, totalitarianism, and belief in malevolent global conspiracies
Authors: Allington Daniel , Hirsh David , Katz Louise
Published: April 2023

Two cross-sectional studies were carried out in order to identify predictors of antisemitism, measured using the Generalised Antisemitism or GeAs scale. In the first, which used a self-selecting sample of UK-resident adults (n = 809), age, gender, ethnicity, and educational level as well as a wide range of ideological predictors were analysed as bivariate predictors of antisemitism. In the second, which used a representative sample of UK-resident adults (n = 1853), the same demographic predictors plus the non-demographic predictors found to have the strongest bivariate relationships with Generalised Antisemitism in the previous study were used to construct a linear model with multiple predictors. Ethnicity, support for totalitarian government, belief in malevolent global conspiracies, and anti-hierarchical aggression were identified as the strongest predictors of Generalised Antisemitism. However, support for totalitarian government was only found to predict ‘old’ antisemitic attitudes (measured using the Judeophobic Antisemitism or JpAs subscale) and not ‘new’ antisemitic attitudes (measured using the Antizionist Antisemitism or AzAs subscale), whereas ethnicity, anti-hierarchical aggression, and belief in malevolent global conspiracies were found to predict both ‘old’ and ‘new’ antisemitic attitudes. This finding adds nuance to ongoing debates about whether antisemitism is more prevalent on the political right or left, by suggesting that (at least in the UK) it is instead associated with a conspiracist view of the world, a desire to overturn the social order, and a preference for authoritarian forms of government—all of which may exist on the right, the left, and elsewhere. Data from both samples are open, as is the code used in order to carry out the analyses presented here.
An importance-performance analysis of teachers’ perception of STEM engineering design education
Authors: Chien Yu-Hung , Chang Fang-Yu
Published: April 2023

There is an increasing worldwide trend toward the development of science, technology, engineering, and mathematics (STEM) education using engineering design (ED) practice. Considering that teachers play pivotal roles in terms of student interest in STEM subjects and careers, it is important to explore teachers’ perceptions of STEM-ED education. We analysed survey data from 184 technology teachers who participated in empowerment training (using a STEM-ED curriculum) in 2017, 2018, 2021, and 2022. We used an importance-performance analytical model to investigate the teachers’ perceptions of STEM-ED itself, its impact on students, and the challenges experienced during implementation. The results showed that various improvements were required for STEM-ED promotion and for the preparation of STEM-ED lessons. Analysis of variance revealed that the age groups taught and the number of weekly teaching hours significantly affected the teachers’ perceptions of STEM-ED. These findings will assist educational institutions worldwide in planning future education policies, designing teacher empowerment courses, and understanding teachers’ needs in efforts to improve STEM-ED.
Fracture forecasting with deep neural networks
Authors: Shapiro Maura
Published: April 2023

DyFraNet is a physics-inspired simulation for investigating how fractures begin and evolve in materials under stress.
Increasing the synchronization stability in complex networks
Authors: Wu Xian , Xi Kaihua , Cheng Aijie , Lin Hai Xiang , van Schuppen Jan H.
Published: April 2023

We aim to increase the ability of coupled phase oscillators to maintain synchronization when the system is affected by stochastic disturbances. We model the disturbances by Gaussian noise and use the mean first hitting time when the state hits the boundary of a secure domain, that is a subset of the basin of attraction, to measure synchronization stability. Based on the invariant probability distribution of a system of phase oscillators subject to Gaussian disturbances, we propose an optimization method to increase the mean first hitting time and, thus, increase synchronization stability. In this method, a new metric for synchronization stability is defined as the probability of the state being absent from the secure domain, which reflects the impact of all the system parameters and the strength of disturbances. Furthermore, by this new metric, one may identify those edges that may lead to desynchronization with a high risk. A case study shows that the mean first hitting time is dramatically increased after solving corresponding optimization problems, and vulnerable edges are effectively identified. It is also found that optimizing synchronization by maximizing the order parameter or the phase cohesiveness may dramatically increase the value of the metric and decrease the mean first hitting time, thus decrease synchronization stability.
The role of acoustofluidics and microbubble dynamics for therapeutic applications and drug delivery
Authors: Kaykanat S. I. , Uguz A. K.
Published: April 2023

Targeted drug delivery is proposed to reduce the toxic effects of conventional therapeutic methods. For that purpose, nanoparticles are loaded with drugs called nanocarriers and directed toward a specific site. However, biological barriers challenge the nanocarriers to convey the drug to the target site effectively. Different targeting strategies and nanoparticle designs are used to overcome these barriers. Ultrasound is a new, safe, and non-invasive drug targeting method, especially when combined with microbubbles. Microbubbles oscillate under the effect of the ultrasound, which increases the permeability of endothelium, hence, the drug uptake to the target site. Consequently, this new technique reduces the dose of the drug and avoids its side effects. This review aims to describe the biological barriers and the targeting types with the critical features of acoustically driven microbubbles focusing on biomedical applications. The theoretical part covers the historical developments in microbubble models for different conditions: microbubbles in an incompressible and compressible medium and bubbles encapsulated by a shell. The current state and the possible future directions are discussed.
Inversion symmetry breaking in spin–orbit torque-induced magnetization switching to improve the recording density of multi-level magnetoresistive random-access memory
Authors: Kamihoki Uraku , Kurokawa Yuichiro , Fujimoto Masahiro , Yuasa Hiromi
Published: April 2023

In this study, we prepared a multi-layer Tb–Fe/Pt/Tb–Fe wire to develop a multi-level magnetic memory. By applying current, magnetizations of the Tb–Fe layers were inversion symmetrically switched by spin– orbit torque (SOT) generated from the middle Pt layer. Measurements of SOT showed that its efficiency had opposite polarities in the top and bottom Tb–Fe layers. The switching current density of the top and bottom Tb–Fe layers shifted in opposite directions under a uniform perpendicular magnetic field. Because the perpendicular magnetic field broke the inversion symmetry of SOT generated from the middle Pt layer, it could be used to control the switching current. Our results prove that the additional uniform and perpendicular magnetic field can enhance the controllability of the magnetization state in case of multi-level SOT-induced magnetization switching.
Effect of partitioning YBaCuO bulk on the levitation force in Halbach external field
Authors: Liu Xiaoning , Si Mayin , Zhang Xiwen , Ke Zhihao , Deng Zigang
Published: April 2023

When a YBaCuO bulk superconductor (SC) is subdivided, its levitation force may not be significantly reduced after this partitioning process. The force will decrease even less if the sectional surface introduced by partitioning is parallel to the induced current loop. Moreover, the levitation force can be maintained because the partitioning makes the SC more magnetizable. These findings have implications for longitudinal maglev technology. A method for calculating levitation forces in nonuniform fields based on critical-state theory is proposed. In this method, an SC is divided into several regions where the external field is approximately uniform within each subvolume. To minimize the force degradation introduced by partitioning, the cutting surfaces should be parallel to the induced current. This approximate approach can effectively reproduce the experiment and improve the calculation accuracy. Another application of combining and recovering discrete SCs is demonstrated, and it is shown that a recombined SC according to the small-loss partitioning condition can achieve 68% of the levitation capacity of an intact sample. In addition, the invisible cracks inside the bulk sample can be predicted by comparing its levitation force with that of the intact sample.
DyFraNet: Forecasting and backcasting dynamic fracture mechanics in space and time using a 2D-to-3D deep neural network
Authors: Hsu Yu-Chuan , Buehler Markus J.
Published: April 2023

The dynamics of material failure is a critical phenomenon relevant to a range of scientific and engineering fields, from healthcare to structural materials. We propose a specially designed deep neural network, DyFraNet, which can predict dynamic fracture behaviors by identifying a complete history of fracture propagation—from the onset of cracking, as a crack grows through the material, modeled as a series of frames evolving over time and dependent on each other. Furthermore, the model can not only forecast future fracture processes but also backcast to elucidate past fracture histories. In this scenario, once provided with the outcome of a fracture event, the model will reveal past events that led to this state and can also predict future evolutions of the failure process. By comparing the predicted results with atomistic-level simulations and theory, we show that DyFraNet can capture dynamic fracture mechanics by accurately predicting how cracks develop over time, including measures such as the crack speed, as well as when cracks become unstable. We use Gradient-weighted Class Activation Mapping, Grad-CAM, to interpret how DyFraNet perceives the relationship between geometric conditions and fracture dynamics, and we find that DyFraNet pays special attention to the areas around crack tips that have a critical influence in the early stage of fracture propagation. In later stages, the model pays increased attention to the existing or newly formed damaged regions in the material. The proposed approach offers the potential to accelerate the exploration of dynamical processes in material design against failure and can be adapted for all kinds of dynamical problems.
Analytical predictions of periodic oscillations in a piezoelectric energy harvester under combined aeroelastic and harmonic excitation
Authors: Yu Bo
Published: April 2023

This work studies a piezoelectric energy harvester subjected to both fluid flow and harmonic excitation. A lumped parameter model that incorporates fluid–structure interaction is presented to analyze the effects of both fluid flow and harmonic excitation on the proposed harvester. The method of implicit mapping is employed to calculate the periodic displacement, voltage, and velocity oscillations. Stabilities and bifurcations of periodic oscillations are determined based on the eigenvalues of the resultant matrix of mapping structures. The displacement and voltage nodes of the proposed energy harvester varying with excitation amplitude and frequency are investigated. The maximum eigenvalue magnitudes are illustrated. Utilizing the periodic nodes of the displacement and voltage, the harmonic amplitudes and phases are calculated using the fast Fourier transform. The harmonic amplitudes of both displacement and voltage varying with excitation frequency are depicted. For the stable periodic responses, the implicit maps and numerical simulations are presented to demonstrate the effectiveness of the energy harvesting system. The theoretical analysis presented in this study can be useful for the design and optimization of the proposed energy harvester.
Complexity of couplings in multivariate time series via ordinal persistent homology
Authors: Haruna Taichi
Published: April 2023

We propose a new measure of the complexity of couplings in multivariate time series by combining the techniques of ordinal pattern analysis and topological data analysis. We construct an increasing sequence of simplicial complexes encoding the information about couplings among the components of a given multivariate time series through the intersection of ordinal patterns. The complexity measure is then defined by making use of the persistent homology groups. We validate the complexity measure both theoretically and numerically.
Hybrid PIC–fluid simulations for fast electron transport in a silicon target
Authors: Yang X. H. , Chen Z. H. , Xu H. , Ma Y. Y. , Zhang G. B. , Zou D. B. , Shao F. Q.
Published: April 2023

Ultra-intense laser-driven fast electron beam propagation in a silicon target is studied by three-dimensional hybrid particle-in-cell–fluid simulations. It is found that the transverse spatial profile of the fast electron beam has a significant influence on the propagation of the fast electrons. In the case of a steep spatial profile (e.g., a super-Gaussian profile), a tight fast electron beam is produced, and this excites more intense resistive magnetic fields, which pinch the electron beam strongly, leading to strong filamentation of the beam. By contrast, as the gradient of the spatial profile becomes more gentle (e.g., in the case of a Lorentzian profile), the resistive magnetic field and filamentation become weaker. This indicates that fast electron propagation in a solid target can be controlled by modulating the spatial gradient of the laser pulse edge.
Non-equilibrium strain induces hysteresis and anisotropy in the quasi-static and dynamic elastic behavior of sandstones: Theory and experiments
Authors: Kober J. , Scalerandi M. , Zeman R.
Published: April 2023

Materials with grain contacts or partially closed cracks exhibit anomalous elastic behavior: hysteresis in quasi-static experiments and slow dynamics in fast dynamic ones. Albeit the behavior in the two cases (which correspond to very different strain ranges) appears different, it should stem from the same physics and, thus, could be modeled by a universal equation of state. We propose a modification of the standard acoustoelastic theory, introducing the concept of conditioning induced non-equilibrium strain, which allows us to predict the evolution of elastic wave velocity in both quasi-static and dynamic ranges, including the velocity anisotropy induced by external uniaxial loading.
Traps inhomogeneity induced conversion of Shockley–Read–Hall recombination in NiO/β-Ga2O3 p+–n heterojunction diodes
Authors: Wang Z. P. , Gong H. H. , Yu X. X. , Hu T. C. , Ji X. L. , Ren F.-F. , Gu S. L. , Zheng Y. D. , Zhang R. , Ye J. D.
Published: April 2023

In this Letter, the trap inhomogeneity within β-Ga2O3 is correlated with the conversion of Shockley–Read–Hall (SRH) recombination in NiO/β-Ga2O3 p+–n heterojunction diodes. For the virgin epi-wafer, both near-surface traps E2 (EC-0.82 eV) and E3 (EC-1.11 eV) and bulk E2* traps (EC-0.76 eV) are identified by a transient capacitance analysis, and the corresponding forward current–voltage characteristics of diodes are well fitted in the framework of field-dependent SRH recombination. The SRH recombination rates for E2, E3, and E2* traps are determined to be 1.3 × 107, 8.6 × 108, and 2.4 × 108 s−1, respectively. In this circumstance, carrier transport under forward bias is governed by trap-assisted tunneling through E3 traps with high recombination rates, and the hysteresis is pronounced. With the removal of the defective surface layer, E2 and E3 traps are almost completely eliminated, together with the reduced density of E2* traps to 5.6 × 1014 cm−3. The resultant diode performs an improved rectification ratio of >1011 at ±3 V and an enhanced reverse breakdown voltage of 1692 V. The elimination of near-surface traps leads to the conversion of carrier transport into the conventional SRH recombination, accompanied by the negligible forward hysteresis characteristics. The established fundamental correlation of carrier transport and traps within Ga2O3 is beneficial to develop a high-performance power rectifier toward practical applications.
ET-AL: Entropy-targeted active learning for bias mitigation in
materials data
Authors: Rondinelli James M. , Chen Wei
Published: April 2023

Growing materials data and data-driven informatics drastically promote the discovery and design of materials. While there are significant advancements in data-driven models, the quality of data resources is less studied despite its huge impact on model performance. In this work, we focus on data bias arising from uneven coverage of materials families in existing knowledge. Observing different diversities among crystal systems in common materials databases, we propose an information entropy-based metric for measuring this bias. To mitigate the bias, we develop an entropy-targeted active learning (ET-AL) framework, which guides the acquisition of new data to improve the diversity of underrepresented crystal systems. We demonstrate the capability of ET-AL for bias mitigation and the resulting improvement in downstream machine learning models. This approach is broadly applicable to data-driven materials discovery, including autonomous data acquisition and dataset trimming to reduce bias, as well as data-driven informatics in other scientific domains.
Li-ion transport at the LiFePO4/γ-Li3PO4 interface and its enhancement through surface nitrogen doping
Authors: Xu Guigui , Lin Hongbin , Zhong Kehua , Zhang Jian-Min , Huang Zhigao
Published: April 2023

The all-solid-state batteries (ASSBs) are of particular interest because of their higher energy density and improved safety. However, the interfacial instability and resulting high interfacial resistance between the cathode and solid electrolyte (SE) have become the major challenges for the practical application of ASSBs. Herein, we report a stable LiFePO4 cathode/γ-Li3PO4 SE interface and systemically investigate the mechanism of Li-ion transport at the interface and the effects of surface nitrogen doping using first-principles calculations. It is found that delithiation at the LiFePO4/γ-Li3PO4 interface initially occurs at the topmost layer of the LiFePO4 cathode side, and hopping through the interface barrier is a rate-limiting step for Li mobility. Nitrogen doping leads to local structural distortion occurred at the interface, affecting the interfacial Li+ diffusion kinetics. Furthermore, the underlying mechanisms in which the different N doping sites alter the Li diffusion barrier are analyzed. We find that, by a rational design, N doping could significantly enhance Li+ diffusion kinetics. Further analysis of the electronic structure of the interface system reveals that the Li3PO4 electrolyte is electrochemically stable against the LiFePO4 cathode in the N-doped interface. Our findings provide a microscopic understanding of the Li+ transport at solid–solid LiFePO4/γ-Li3PO4 interface and suggest that controlling synthesis condition can be critical for enhancing Li+ transport at the N-doped LiFePO4/γ-Li3PO4 interface in an ASSB.
Super-Fermi acceleration in multiscale MHD reconnection
Authors: Majeski Stephen , Ji Hantao
Published: April 2023

We investigate the Fermi acceleration of charged particles in 2D MHD anti-parallel plasmoid reconnection, finding a drastic enhancement in energization rate ε ̇ over a standard Fermi model of ε ̇ ∼ ε. The shrinking particle orbit width around a magnetic island due to E → × B → drift produces a ε ̇ ∥ ∼ ε ∥ 1 + 1 / 2 χ power law with χ ∼ 0.75. The increase in the maximum possible energy gain of a particle within a plasmoid due to the enhanced efficiency increases with the plasmoid size and is by multiple factors of 10 in the case of solar flares and much more for larger plasmas. Including the effects of the non-constant E → × B → drift rates leads to further variation in power law indices from ≳ 2 to ≲ 1, decreasing with plasmoid size at the time of injection. The implications for energetic particle spectra are discussed alongside applications to 3D plasmoid reconnection and the effects of a guide field.
Effects of temperature and DC cycling stress on resistive switching mechanisms in hafnia-based ferroelectric tunnel junction
Authors: Shin Wonjun , Koo Ryun-Han , Min Kyung Kyu , Kwak Been , Kwon Dongseok , Kwon Daewoong , Lee Jong-Ho
Published: April 2023

We propose an accurate and effective method, low-frequency noise (LFN) spectroscopy, to examine the resistive switching mechanism in ferroelectric tunnel junctions (FTJs) based on pure hafnium oxide (HfOx). Contrary to previous studies that primarily focused on the ferroelectric (FE) resistive switching (RS) in HfOx-based FTJs, the results of this study demonstrate that non-FE RS affected by the redistribution of oxygen vacancies also plays a significant role in determining the performance of FTJs. LFN spectroscopy is conducted in different conditions by changing the operating temperature and inducing DC cycling stress. The results reveal that the RS mechanism changes from FE to non-FE RS with increased program bias in all conditions. This change is facilitated by the rise in temperature and the number of DC cycling stress.
Hydrogenation of p+ poly-Si by
Al2O3 nanolayers prepared by atomic layer
deposition
Authors: Theeuwes Roel J. , Melskens Jimmy , Beyer Wolfhard , Breuer Uwe , Gutjahr Astrid , Mewe Agnes A. , Macco Bart , Kessels Wilhelmus M. M.
Published: April 2023

Polysilicon (poly-Si) passivating contacts have enabled some of the highest lab-scale crystalline silicon (c-Si) solar cell conversion efficiencies, largely due to their excellent surface passivation quality, which can be aided by means of hydrogenation treatments. One frequently applied method is to use hydrogen-rich capping layers, such as Al2O3 or SiNx, which can provide hydrogen to the poly-Si/SiOx/Si interface upon annealing. In this work, the effect of the deposition conditions of the Al2O3 layers, fabricated by various types of atomic layer deposition (ALD), on the hydrogenation of p+ poly-Si is investigated, and it is compared to the direct passivation of c-Si by the same Al2O3 layers. It is found that excellent hydrogenation of the p+ poly-Si by Al2O3 could be reached by a wide range of ALD conditions, but higher annealing temperatures were required as compared to passivation of c-Si. The different ALD conditions result in Al2O3 layers with varying refractive indices, O/Al ratios, and hydrogen content, although these material properties become highly similar upon annealing. Furthermore, the p+ poly-Si layer appears to act as a reservoir for hydrogen, which alters the hydrogen effusion profiles of the Al2O3 layers. The results show that a wide range of Al2O3 layers are highly suitable for hydrogenation of p+ poly-Si and provide more insight into the hydrogenation process of poly-Si passivating contacts.
Minimization of the electrical contact resistance in thin-film thermoelectric device
Authors: Tan Ming , Liu Wei-Di , Shi Xiao-Lei , Sun Qiang , Chen Zhi-Gang
Published: April 2023

High electrical contact resistance refrains the performance of thin-film thermoelectric devices at the demonstrative level. Here, an additional Ti contact layer is developed to minimize the electrical contact resistance to ∼4.8 Ω in an as-assembled thin-film device with 50 pairs of p–n junctions. A detailed interface characterization demonstrates that the low electrical contact resistance should be mainly attributed to the partial epitaxial growth of Bi2Te3-based thin-film materials. Correspondingly, the superlow electrical contact resistance facilitates the applicability of the out-of-plane thin-film device and results in an ultrahigh surface output power density of ∼81 μW cm−2 at a low temperature difference of 5 K. This study illustrates the Ti contact layer that strengthens the contact between Cu electrodes and Bi2Te3-based thermoelectric thin films mainly through partial epitaxial growth and contributes to high-performance thin-film thermoelectric devices.
Low-efficiency-droop c-plane InGaN/GaN light-emitting diodes through the use of thick single quantum wells and doped barriers
Authors: Chow Y. C. , Lynsky C. , Nakamura S. , DenBaars S. P. , Weisbuch C. , Speck J. S.
Published: April 2023

Efficiency droop at high current densities is a problem for InGaN-based light-emitting diodes (LEDs), especially for conventional c-plane devices. The large internal electric fields in c-plane quantum wells (QWs) lead to an increase in the active region carrier density (n), causing the electrical efficiency droop onset to occur at low current densities. Here, we present an approach to reduce the internal electric fields (Eint) in c-plane QWs by placing doped p-type and n-type GaN barriers close to the QW. The reduced Eint also allows a thick QW active region design, which helps to lower n to further reduce the droop. The concept of using doped barriers to control Eint is explained using theory and device simulations. Following that, multiple series of thick single QW (SQW) LEDs were grown and characterized. Key parameters in the epitaxial design such as the doping levels and the relative position of the doped barriers were systematically studied and optimized. By using optimized doped barriers and a thick SQW, c-plane LEDs with a low-efficiency droop of 14% at 300 A/cm2 [with respect to the peak external quantum efficiency (EQE)] and a high peak EQE of 49% were demonstrated.
Machine learning and polymer self-consistent field theory in two spatial dimensions
Authors: Xuan Yao , Delaney Kris T. , Ceniceros Hector D. , Fredrickson Glenn H.
Published: April 2023

A computational framework that leverages data from self-consistent field theory simulations with deep learning to accelerate the exploration of parameter space for block copolymers is presented. This is a substantial two-dimensional extension of the framework introduced in the work of Xuan et al. [J. Comput. Phys. 443, 110519 (2021)]. Several innovations and improvements are proposed. (1) A Sobolev space-trained, convolutional neural network is employed to handle the exponential dimension increase of the discretized, local average monomer density fields and to strongly enforce both spatial translation and rotation invariance of the predicted, field-theoretic intensive Hamiltonian. (2) A generative adversarial network (GAN) is introduced to efficiently and accurately predict saddle point, local average monomer density fields without resorting to gradient descent methods that employ the training set. This GAN approach yields important savings of both memory and computational cost. (3) The proposed machine learning framework is successfully applied to 2D cell size optimization as a clear illustration of its broad potential to accelerate the exploration of parameter space for discovering polymer nanostructures. Extensions to three-dimensional phase discovery appear to be feasible.
Simple and efficient algorithms based on Volterra equations to compute memory kernels and projected cross-correlation functions from molecular dynamics
Authors: Obliger Amaël
Published: April 2023

Starting from the orthogonal dynamics of any given set of variables with respect to the projection variable used to derive the Mori–Zwanzig equation, a set of coupled Volterra equations is obtained that relate the projected time correlation functions between all the variables of interest. This set of equations can be solved using standard numerical inversion methods for Volterra equations, leading to a very convenient yet efficient strategy to obtain any projected time correlation function or contribution to the memory kernel entering a generalized Langevin equation. Using this strategy, the memory kernel related to the diffusion of tagged particles in a bulk Lennard–Jones fluid is investigated up to the long-term regime to show that the repulsive–attractive cross-contribution to memory effects represents a small but non-zero contribution to the self-diffusion coefficient.
Photoinduced electron transfer across the polymer-capped CsPbBr3 interface in a polar medium
Authors: Kipkorir Anthony , Jin Xiuyu , Gao Haifeng , Kamat Prashant V.
Published: April 2023

In-situ polymer capping of cesium lead bromide (CsPbBr3) nanocrystals with polymethyl acrylate is an effective approach to improve the colloidal stability in the polar medium and thus extends their use in photocatalysis. The photoinduced electron transfer properties of polymethyl acrylate (PMA)-capped CsPbBr3 nanocrystals have been probed using surface-bound viologen molecules with different alkyl chains as electron acceptors. The apparent association constant (Kapp) obtained for the binding of viologen molecules with PMA-capped CsPbBr3 was 2.3 × 107 M−1, which is an order of magnitude greater than that obtained with oleic acid/oleylamine-capped CsPbBr3. Although the length of the alkyl chain of the viologen molecule did not show any impact on the electron transfer rate constant, it influenced the charge separation efficiency and net electron transfer quantum yield. Viologen moieties with a shorter alkyl chain length exhibited a charge separation efficiency of 72% compared with 50% for the longer chain alkyl chain length viologens. Implications of polymer-capped CsPbBr3 perovskite nanocrystals for carrying out photocatalytic reduction in the polar medium are discussed.
Three-dimensional angle-resolved photoemission study of bulk SiGe single crystals
Authors: Takahashi Kazutoshi , Umeda Yuki , Imamura Masaki , Takaira Marina , Ikoma Yoshifumi , Arai Yasutomo
Published: April 2023

The composition- and structure-dependent electronic band structure of SiGe alloys facilitates a rich variety of its application in various fields. In this study, we performed high-resolution core-level and angle-resolved photoemission spectroscopy (ARPES) of unstrained SiGe single crystals with the (001) surface. Thermally cleaned surfaces of the single crystals of SiGe alloys exhibited double domain (2 × 1) reconstruction, wherein the asymmetric dimer was composed of Ge atoms, and Si atoms were located below the subsurface region. The compositional dependence of three valence bands and their constant energy contours were clearly resolved by three-dimensional ARPES measurements using the high-intensity synchrotron radiation. The valence bands of unstrained SiGe alloys could be well described by the composition-based interpolation of the band parameters of pristine Si and Ge crystals.
The calculations of thermophysical properties of low-temperature indium plasma
Authors: Apfelbaum E. M.
Published: April 2023

A model for calculation of thermophysical properties (pressure, internal energy, electrical and thermal conductivities, and thermal power) of low-temperature indium plasma is developed at the temperatures 8–100 kK and densities less than 9 g/cm3. It is constructed on the basis of a chemical approach and a relaxation time approximation. The former allows us to obtain the chemical (ionic) composition of indium plasma together with the other thermodynamical values. There have not been any published data concerning these properties in this area for indium plasma up until now, excluding for the semi-empirical models. The area of applicability of the present model has also been estimated. The fitting analytical relations for calculated values, which can be used in practical applications, are constructed.
High sensitivity HgTe room temperature terahertz photodetector
Authors: Zuo Xinrong , Zhu Chenwei , Yao Chenyu , Hu Zhen , Wu Yan , Fan Liuyan , Li Zhifeng , He Jun , Chen Xiaoshuang , Chen Pingping , Yuan Xiaoming , Wang Lin , Lu Wei
Published: April 2023

The advent of topological semi-metals with peculiar band structure and exotic quantum-transport provides novel pathways for upgrading the performance of terahertz (THz) detection. HgTe is among such a candidate with the unique advantages of a negative bandgap, ultra-high mobility, and thermoelectricity, which ignites the possibility of addressing the technical bottlenecks of traditional routes for THz detection. Herein, for the first time, we report large-area (3 in.) growth of high-mobility HgTe thin-film via molecular-beam epitaxial and the implementation of bow-tie antennas based HgTe THz-detector with the abilities of ultrafast response, low noise, and high ambient-stability at room temperature. By exploration of strong light-coupling and superior hot-carrier transport, the bow-tie antenna-based HgTe photodetector can achieve a responsivity of 0.04 A/W and a noise equivalent power of less than 0.6 nW/Hz1/2 at 0.3 THz. Furthermore, the sensitivity can be further improved by nearly an order of magnitude up to 0.36 A/W at 0.3 THz by incorporating a short channel asymmetric cubic resonator. The reported performances allow a realistic exploration of high-mobility bulk states in topological semimetals for large area, fast-imaging applications in the THz band.
Room-temperature magnetoresistance in a single-layer composite film based on noncollinear antiferromagnetic Mn3Sn
Authors: Wang Xiaoning , Chen Hongyu , Yan Han , Qin Peixin , Zhou Xiaorong , Meng Ziang , Liu Li , Liu Xiaofang , Wang Hui , Liu Zhiqi
Published: April 2023

The recently discovered room-temperature magnetoresistance in all-antiferromagnetic tunnel junctions is promising for highly integrated ultrafast memory applications. Here, we report a room-temperature magnetoresistance effect in a single-layer composite film consisting of noncollinear antiferromagnetic Mn3Sn and nonmagnetic Ag. A room-temperature butterfly like magnetoresistance of ∼0.3% is obtained for the Mn3Sn–Ag composite film, which is induced by the giant magnetoresistance effect governed by the magnetic octupole induced momentum space spin splitting in the noncollinear antiferromagnet Mn3Sn. Moreover, compared to the complicated multilayer all-antiferromagnetic tunnel junction structures, the simple fabrication process of single-layer composite films in this work could facilitate the application of antiferromagnetic magnetoresistance devices.
Spin-strain coupling in nanodiamonds as a unique cluster identifier
Authors: Awadallah Asad , Zohar Inbar , Finkler Amit
Published: April 2023

Fluorescent nanodiamonds have been used to a large extent in various biological systems due to their robust nature, their inert properties, and the relative ease of modifying their surface for attachment to different functional groups. Within a given batch, however, each nanodiamond is indistinguishable from its neighbors and, so far, one could only rely on fluorescence statistics for some global information about the ensemble. Here, we propose and measure the possibility of adding another layer of unique information, relying on the coupling between the strain in the nanodiamond and the spin degree-of-freedom in the nitrogen-vacancy center in diamond. We show that the large variance in axial and transverse strain can be encoded to an individual radio frequency identity for a cluster of nanodiamonds. When using single nanodiamonds, this unique fingerprint can then be potentially tracked in real-time in, e.g., cells, as their size is compatible with metabolism intake. From a completely different aspect, in clusters of nanodiamonds, this can already serve as a platform for anti-counterfeiting measures.
Spectral inequality for Dirac right triangles
Authors: Vu Tuyen
Published: April 2023

We consider a Dirac operator on right triangles, subject to infinite-mass boundary conditions. We conjecture that the lowest positive eigenvalue is minimized by the isosceles right triangle under the area or perimeter constraints. We prove this conjecture under extra geometric hypotheses relying on a recent approach of Briet and Krejčiřík [J. Math. Phys. 63, 013502 (2022)].