bluuebunny/crossref_metadata_2025 huggingface dataset:
Die Tumorstammzellnische im Kopf-Hals-Bereich – Knotenpunkt mit therapeutischem Potenzial?
Authors: Lammert Anne , Affolter Annette , Gvaramia David , Heid Jonas , Jungbauer Frederic , Scherl Claudia , Tenschert Esther , Rotter Nicole , Willett Nicola , Kern Johann
Published: January 2021

In den letzten Jahren verdichten sich Hinweise, dass eine Tumorstammzellpopulation in Plattenepithelkarzinomen der Kopf-Hals-Region (HNSCC) existiert. Man vermutet, dass diese Tumorstammzellen (CSC) über Selbsterneuerungskapazität verfügen und für Wachstum, Metastasierung, Rekurrenz und Therapieresistenz des Tumors essenziell sind. Stammzellen werden von einer spezialisierten zellulären und nichtzellulären Mikroumgebung unterstützt, die „Stammzellnische“ genannt wird. Eine mögliche Strategie, um CSC zu attackieren, könnte eine Beeinflussung ihrer Nische sein.

Stromal cell-derived factor-1 (SDF-1) gilt als Schlüsselregulator des Zellverkehrs zwischen Nische und der peripheren Blutzirkulation. SDF-1 ist ein multifunktionelles Zytokin, das u. a. von Endothel-/Stromazellen sezerniert wird. Als sein Rezeptor wurde der 7-Transmembranrezeptor CXCR4 identifiziert. Die SDF-1-CXCR4-Achse ist ein wesentlicher Faktor für Migration und Mobilisation von CSC in und aus ihrer Nische. Ihre Existenz und Funktionalität in der Tumorstammzellnische von HNSCC konnte bereits nachgewiesen werden. Strategien, die in diese Interaktion eingreifen, könnten einen entscheidenden Beitrag in der Therapie von HNSCC bieten.

Um Mechanismen in der Tumorstammzellnische von HNSCC in vitro zu untersuchen, werden Modelle benötigt. Wir erwarten, dass die 3D-Zellkultur und das 3D-Bioprinting bei der Entwicklung neuer, individualisierter Therapiestrategien bahnbrechenden Charakter aufweisen werden.

Hier geben wir eine Übersicht über den Wissensstand hinsichtlich der Interaktionen in der Tumorstammzellnische von HNSCC am Beispiel der SDF-1-CXCR4-Achse.
Development of a Physiologically-Based Pharmacokinetic (PBPK) Model of Nebulized Hydroxychloroquine for Pulmonary Delivery to COVID-19 Patients
Authors: Idkaidek Nasir , Hawari Feras , Dodin Yasmeen , Obeidat Nour
Published: January 2021

Despite inconclusive evidence, chloroquine (CQ) and hydroxychloroquine (HCQ)are commonly used for the treatment of Corona virus Disease 2019(COVID-19) in critically ill patients.It was hypothesized that HCQ as an aerosol application can reach the antiviral concentration of ~1–5 μM in the alveolar cells which has been proven effective in vitro. A physiologically-based pharmacokinetic (PBPK) model of nebulized HCQ for pulmonary delivery to COVID-19 patients using the Nasal-Pulmonary Module in GastroPlus® V9.7 simulator, in order to calculate the necessary inhalation dose regimen of HCQ, was developed. The physiological, drug disposition, and pharmacokinetic parameters were obtained from the literature and used during model building after optimization using Optimization Module, while oral data was used for validation. The 25 mg BID inhalation dosing was predicted to lead to alveolar HCQ levels of 7 µM (above EC50 of ~1–5 µM), and small plasma levels of 0.18 µM (as compared to plasma levels of 3.22 µM after 200 mg BID oral dosing). However, average contact time (>1 µM) is around 0.5 h in lung parts, suggesting indirect exposure response effect of HCQ.The developed PBPK model herein predicted HCQ levels in plasma and different lung parts of adults after multiple inhalation dosing regimens for 5 days. This in-silico work needs to be tested in vivo on healthy subjects and COVID-19 patients using 12.5 mg BID and 25 mg BID inhalation doses.
Endoscopic full-thickness resection of polyps involving the appendiceal orifice: a multicenter international experience
Authors: Ichkhanian Yervant , Barawi Mohammed , Seoud Talal , Thakkar Shyam , Kothari Truptesh H. , Halabi Maan El , Ullah Asad , Edris Wedi , Aepli Patrick , Kowalski Thomas , Shinn Brianna , Shariaha Reem Z. , Mahadev Srihari , Mosko Jeffrey D. , Andrisani Gianluca , Di Matteo Francesco Maria , Albrecht Heinz , Giap Andrew Q. , Tang Shou-jiang , Naga Yehia M. , van Geenen Erwin , Friedland Shai , Tharian Benjamin , Irani Shayan , Ross Andrew S. , Jamil Laith H. , Lew Daniel , Nett Andrew S. , Farha Jad , Runge Thomas M. , Jovani Manol , Khashab Mouen A.
Published: January 2021

Background Endoscopic resection of lesions involving the appendiceal orifice remains a challenge. We aimed to report outcomes with the full-thickness resection device (FTRD) for the resection of appendiceal lesions and identify factors associated with the occurrence of appendicitis.

Methods This was a retrospective study at 18 tertiary-care centers (USA 12, Canada 1, Europe 5) between November 2016 and August 2020. Consecutive patients who underwent resection of an appendiceal orifice lesion using the FTRD were included. The primary outcome was the rate of R0 resection in neoplastic lesions, defined as negative lateral and deep margins on post-resection histologic evaluation. Secondary outcomes included the rates of: technical success (en bloc resection), clinical success (technical success without need for further surgical intervention), post-resection appendicitis, and polyp recurrence.

Results 66 patients (32 women; mean age 64) underwent resection of colonic lesions involving the appendiceal orifice (mean [standard deviation] size, 14.5 (6.2) mm), with 40 (61 %) being deep, extending into the appendiceal lumen. Technical success was achieved in 59/66 patients (89 %), of which, 56 were found to be neoplastic lesions on post-resection pathology. Clinical success was achieved in 53/66 (80 %). R0 resection was achieved in 52/56 (93 %). Of the 58 patients in whom EFTR was completed who had no prior history of appendectomy, appendicitis was reported in 10 (17 %), with six (60 %) requiring surgical appendectomy. Follow-up colonoscopy was completed in 41 patients, with evidence of recurrence in five (12 %).

Conclusions The FTRD is a promising non-surgical alternative for resecting appendiceal lesions, but appendicitis occurs in 1/6 cases.
Effect of Anabolic–Androgenic Steroid Abuse on the Contact Activation System
Authors: Sidelmann Johannes Jakobsen , Gram Jørgen Brodersen , Palarasah Yaseelan , Rasmussen Jon Jarløv , Kistorp Caroline
Published: January 2021

The effect of anabolic–androgenic steroid (AAS) abuse on the contact activation system (CAS) is not known in detail. We hypothesized that current AAS abuse reduces the kallikrein-generating capacity of CAS significantly and investigated the impact of AAS on the proteins and capacity of CAS in current and former AAS abusers and healthy age-matched controls. Men 18 to 50 years of age were included as current AAS abusers, former AAS abusers, or controls. Blood samples were collected after overnight fasting. Kallikrein generation (lag time, peak height, and endogenous kallikrein potential [EKP]), coagulation factor XII (FXII), prekallikrein, high-molecular-weight kininogen (HK), and Complement C1 esterase inhibitor (C1inh) were assessed. Groups were compared by analysis of variance or Kruskal–Wallis test and probabilities were corrected for multiple comparisons. Associations were evaluated by linear regression models. The EKP was significantly reduced in current (n = 37) AAS abusers (984 ± 328 nmol/L × min) compared with former (n = 33) abusers (1,543 ± 481 nmol/L × min) and controls (n = 30) (1,521 ± 339 nmol/L × min), p < 0.001. Current abusers had higher levels of FXII and C1inh and lower levels of prekallikrein and HK than controls, p ≤ 0.025. Stepwise regression analysis showed that EKP was associated with C1inh and prekallikrein in current AAS abusers, R
2 = 0.70, p < 0.001. We conclude that current AAS abuse reduces the kallikrein-generating capacity of CAS by increasing the concentration of C1inh and reducing the concentration of prekallikrein. These changes may contribute to the anti-inflammatory effect of testosterone.
Regioselective Oxidative Cross-Coupling Reaction: Synthesis of Imidazo[1,2-a]pyridine Fluorophores
Authors: Chu Xianglong , Niu Yadi , Ma Chen , Wang Xiaodong , Lin Yunliang , Li Fuwei
Published: January 2021

A rapid access to a series of N-heteroarene fluorophores has been developed on the basis of the palladium-catalyzed direct oxidative C–H/C–H coupling of imidazo[1,2-a]pyridines with thiophenes/furans. The photophysical properties–structure relationship was systematically investigated. The resulting N-heteroarene fluorophores present color-tunable emissions (λem: 431–507 nm in CH2Cl2) and high fluorescence quantum yields (up to 91% in CH2Cl2).
Rhodium(III)-Catalyzed C–H Activation: Annulation of Petrochemical Feedstocks for the Construction of Isoquinolone Scaffolds
Authors: Patman Ryan L. , Barber Joyann S. , Kong Dehuan , Li Wei , McAlpine Indrawan J. , Nair Sajiv K. , Sakata Sylvie K. , Sun Nicole
Published: January 2021

We describe a simple and robust procedure for the Rh(III)-catalyzed [4+2] cycloaddition of feedstock gases enabled through C–H activation. A diverse set of 3,4-dihydroisoquinolones and 3-methylisoquinolones have been prepared in good to excellent yields. The effects of using ethylene and propyne as coupling partners on C–H site selectivity have also been explored with a representative set of substrates and are discussed herein.
Data Collection during the COVID-19 Pandemic: Learning from Experience, Resulting in a Bayesian Repertory
Authors: Rutten Lex , Smedley Tom , Ives Galen , Gold Peter , Merizalde Bernardo , van Haselen Robbert , Manchanda Raj Kumar , Ross Ashley , Cataldi Gustavo , Agaoglu Altunay , di Giampietro Tiziana , Lilas Theodore , Schroyens Frederik , Eizayaga José E.
Published: January 2021

Background A novel pandemic disease offered the opportunity to create new, disease-specific, symptom rubrics for the homeopathic repertory.

Objective The aim of this study was to discover the relationship between specific symptoms and specific medicines, especially of symptoms occurring frequently in this disease.

Materials and Methods Worldwide collection of data in all possible formats by various parties was coordinated by the Liga Medicorum Homeopathica Internationalis. As the data came in, more symptoms were assessed prospectively. Frequent analysis and feedback by electronic newsletters were used to improve the quality of the data. Likelihood ratios (LRs) of symptoms were calculated. An algorithm for combining symptom LRs was programmed and published in the form of an app. The app was tested against 18 well-described successful cases from Hong Kong.

Results LRs of common symptoms such as ‘Fatigue’ and ‘Headache’ provided better differentiation between medicines than did existing repertory entries, which are based only on the narrow presence or absence of symptoms. A mini-repertory for COVID-19 symptoms was published and supported by a web-based algorithm. With a choice of 20 common symptoms, this algorithm produced the same outcome as a full homeopathic analysis based upon a larger number of symptoms, including some that are traditionally considered more specific to particular medicines.

Conclusion A repertory based on clinical data and LRs can differentiate between homeopathic medicines using a limited number of frequently occurring epidemic symptoms. A Bayesian computer algorithm to combine symptoms can complement a full homeopathic analysis of cases.
Increasing the Awareness of Autism Spectrum Disorder with Training of Pre-School Teachers and School Counselors in Turkey
Authors: Kara Halil , Demirtaş Mehmet Semih
Published: January 2021

Training programs for the awareness of autism for professions are supported under the leadership of the United Nations. Misinformation can cause socially destructive results as that which is incorrect is assumed to be known correctly. This study included a total of 308 participants comprising 226 (73.4%) preschool teachers and 82 (26.6%) school counselors. The basic questions related to the awareness and knowledge of autism spectrum disorder (ASD) were selected based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2). It was attempted to categorize the questions into four fields: (1) social interaction, (2) social communication and speech, (3) limited interest pattern with stereotypical and ritualistic behaviors, and (4) comorbidities, etiological characteristics, and the relationship between vaccinations and autism. The results of the study indicate that the awareness of ASD, including core symptoms, was extremely lacking in preschool teachers and school counselors. Moreover, they had extreme prejudice to information known to be incorrect.
Robotic-Assisted Peripheral Nerve Surgery: A Systematic Review
Authors: Chen Lisa Wen-Yu , Goh Mei , Goh Raymond , Chao Yin-Kai , Huang Jung-Ju , Kuo Wen-Ling , Sung Cheyenne Wei-Hsuan , Chuieng-Yi Lu Johnny , Chuang David Chwei-Chin , Chang Tommy Nai-Jen
Published: January 2021

Background Robotic-assisted techniques are a tremendous revolution in modern surgery, and the advantages and indications were well discussed in different specialties. However, the use of robotic technique in plastic and reconstructive surgery is still very limited, especially in the field of peripheral nerve reconstruction. This study aims to identify current clinical applications for peripheral nerve reconstruction, and to evaluate the advantages and disadvantages to establish potential uses in the future.

Methods A review was conducted in the literatures from PubMed focusing on currently published robotic peripheral nerve intervention techniques. Eligible studies included related animal model, cadaveric and human studies. Reviews on robotic microsurgical technique unrelated to peripheral nerve intervention and non-English articles were excluded. The differences of wound assessment and nerve management between robotic-assisted and conventional approach were compared.

Results Total 19 studies including preclinical experimental researches and clinical reports were listed and classified into brachial plexus reconstruction, peripheral nerve tumors management, peripheral nerve decompression or repair, peripheral nerve harvesting, and sympathetic trunk reconstruction. There were three animal studies, four cadaveric studies, eight clinical series, and four studies demonstrating clinical, animal, or cadaveric studies simultaneously. In total 53 clinical cases, only 20 (37.7%) cases were successfully approached with minimal invasive and intervened robotically; 17 (32.1%) cases underwent conventional approach and the nerves were intervened robotically; 12 (22.6%) cases converted to open approach but still intervened the nerve by robot; and 4 (7.5%) cases failed to approach robotically and converted to open surgery entirely.

Conclusion Robotic-assisted surgery is still in the early stage in peripheral nerve surgery. We believe the use of the robotic system in this field will develop to become popular in the future, especially in the fields that need cooperation with other specialties to provide the solutions for challenging circumstances.
Exploring the multi-fractal nature of the air flow and pollutant dispersion in a turbulent urban atmosphere and its implications for long range pollutant transport
Authors: Mouzourides Petros , Kyprianou Andreas , Neophytou Marina K.-A.
Published: January 2021

This work investigates the multi-fractal nature of a turbulent urban atmosphere using high-resolution atmospheric data. Meteorological and concentration measurements of passive and reactive pollutants collected over a 3-year period in a sub-urban high-Reynolds number atmospheric field were analyzed. Scaling laws characterizing the self-similarity and thereby depicting the multi-fractal nature are determined by calculating the singularity spectra, where a range of Hölder exponents, h, are estimated. In doing so, the complexity of the urban atmosphere entailing different stability regimes was addressed. Using the Monin-Obukhov length (LMO) as a marker of atmospheric stability and thereby an indication of the magnitude of anisotropy, we find where and how self-similarity is manifested relative to the different regimes and we estimate corresponding appropriate scaling laws. We find that the wind speed obeys the −5/3 law suggested by Kolmogorov only when the atmosphere lies within the stable regime as defined by Monin-Obukhov theory. Specifically, when the ratio of the atmospheric boundary layer height (Hb.l) over LMO is greater than 15, and at the same time, the ratio of the height above ground of the wind measurements (z0) over LMO is higher than 3 (i.e., in stable regime), then the singularity spectra of wind speed time series indicate that the dominant Hölder exponent, hmax, coincides with Kolmogorov’s second hypothesis. On the contrary under unstable regimes in the atmosphere where the anisotropy is approached, different scaling laws are estimated. In detail, when z0/LMO<0, the dominant Hölder exponent, hmax, of the singularity spectra of the wind speed time series is either negative or close to zero, which is an indication of an impulse-like singularity, that is associated with rapid changes. For the ambient temperature and air quality measurements such as of carbon monoxide and particulate matter concentrations, it was found that they obey different laws, which are related with the long-term correlation of their data fluctuation.
Probabilistic response of a fractional-order hybrid vibration energy harvester driven by random excitation
Authors: Sun Ya-Hui , Yang Yong-Ge , Zhang Ying , Xu Wei
Published: January 2021

The stochastic response of a fractional-order hybrid vibration energy harvester is investigated in this paper. Equivalent system can be derived by the variable transformation. Then, the probability density functions of mechanical states are obtained by the stochastic averaging technique. The good agreement between numerical simulation and analytical results demonstrates the effectiveness of the proposed method. Mean square voltage, mean square current, and mean output power are presented to illustrate the device output performance. Results imply that the hybrid vibration energy harvesting system can generate higher mean output power than that from a separate piezoelectric system and an electromagnetic system.
Mixed modeling for large-eddy simulation: The single-layer and two-layer minimum-dissipation-Bardina models
Authors: Streher L. B. , Silvis M. H. , Cifani P. , Verstappen R. W. C. P.
Published: January 2021

Predicting the behavior of turbulent flows using large-eddy simulation requires a modeling of the subgrid-scale stress tensor. This tensor can be approximated using mixed models, which combine the dissipative nature of functional models with the capability of structural models to approximate out-of-equilibrium effects. We propose a mathematical basis to mix (functional) eddy-viscosity models with the (structural) Bardina model. By taking an anisotropic minimum-dissipation (AMD) model for the eddy viscosity, we obtain the (single-layer) AMD–Bardina model. In order to also obtain a physics-conforming model for wall-bounded flows, we further develop this mixed model into a two-layer approach: the near-wall region is parameterized with the AMD–Bardina model, whereas the outer region is computed with the Bardina model. The single-layer and two-layer AMD–Bardina models are tested in turbulent channel flows at various Reynolds numbers, and improved predictions are obtained when the mixed models are applied in comparison to the computations with the AMD and Bardina models alone. The results obtained with the two-layer AMD–Bardina model are particularly remarkable: both first- and second-order statistics are extremely well predicted and even the inflection of the mean velocity in the channel center is captured. Hence, a very promising model is obtained for large-eddy simulations of wall-bounded turbulent flows at moderate and high Reynolds numbers.
Optically induced temperature variations in a two-layer volume absorber including thermal memory effects
Authors: Popovic M. N. , Markushev D. D. , Nesic M. V. , Jordovic-Pavlovic M. I. , Galovic S. P.
Published: January 2021

In this paper, a theoretical model of temperature variations is derived for a two-layer optically absorbing structure, including thermal memory effects. It is considered that the two-layer structure is surrounded by gas and illuminated on the front side by a harmonically modulated laser beam. This model is based on the hyperbolic theory of heat conduction and Beer–Lambert's law of absorption neglecting multiple optical reflections in each layer. The derived model represents the generalization of the current models in two aspects. First, the influence of thermal memory properties of both layers is accounted for, and second, both layers are regarded as volume absorbers of the incident light. Based on the derived model, the expressions for surface temperature variations are given and discussed for the special type of two-layer structures, irradiated on the coated side, which is a prominent configuration in photoacoustic and photothermal experiments. It is shown that there exists a frequency range in which the influence of the thermal properties of the coating cannot be neglected, especially at the high-frequency range in which thermal memory of coating becomes significant. It is an important result in terms of understanding experimentally measured photothermal and photoacoustic response and, consequently, accurate characterizations of various high optically reflected and/or optically transparent samples by using these experimental techniques.
An experimental setup for dip-coating of thin films for organic solar cells under microgravity conditions
Authors: Ericsson Leif K. E. , Jalan Ishita , Vaerneus Alf , Tomtlund Thomas , Ångerman Maria , van Stam Jan
Published: January 2021

We report the design and testing of a custom-built experimental setup for dip-coating from volatile solutions under microgravity conditions onboard an aircraft. Function and safety considerations for the equipment are described. The equipment proved to work well, both concerning the safety and the preparation of thin films. No leakage of the solvents, nor the solvent vapors, was detected, not even in a situation with a fluctuating gravitational field due to bad weather conditions. We have shown that the equipment can be used to prepare thin films of polymer blends, relevant for organic solar cells, from solution in a feasible procedure under microgravity conditions. The prepared films are similar to the corresponding films prepared under 1 g conditions, but with differences that can be related to the absence of a gravitational field during drying of the applied liquid coating. We report on some introductory results from the characterization of the thin films that show differences in film morphology and structure sizes.
Classification of translation invariant topological Pauli stabilizer codes for prime dimensional qudits on two-dimensional lattices
Authors: Haah Jeongwan
Published: January 2021

We prove that on any two-dimensional lattice of qudits of a prime dimension, every translation invariant Pauli stabilizer group with local generators and with the code distance being the linear system size is decomposed by a local Clifford circuit of constant depth into a finite number of copies of the toric code stabilizer group (Abelian discrete gauge theory). This means that under local Clifford circuits, the number of toric code copies is the complete invariant of topological Pauli stabilizer codes. Previously, the same conclusion was obtained under the assumption of nonchirality for qubit codes or the Calderbank–Shor–Steane structure for prime qudit codes; we do not assume any of these.
Study of two stream instabilities in Lorentzian dusty plasma
Authors: Paul Samit , Denra Raicharan , Sarkar Susmita
Published: January 2021

Two-stream instabilities in an unmagnetized Lorentzian dusty plasma have been investigated using a kinetic theory approach. The occurrence of this instability is discussed in the case of three different plasma wave modes. The first one is the instability of the Langmuir wave driven by streaming suprathermal electrons. The second one is the instability of the dust ion-acoustic wave driven by streaming suprathermal electrons, ions, and dust grains. The last one is concerned with the instability of the dust acoustic wave driven by streaming suprathermal dust grains. Using the Lorentzian kappa velocity distribution function, the real and imaginary frequencies of these waves have been derived analytically. The effect of the suprathermal particle density and the streaming particle density on the real and imaginary frequencies of the waves is examined numerically.
Comparing temperature convergence of shocked thin films of tin and iron to a bulk temperature source
Authors: Brantley David A. , Crum Ryan S. , Akin Minta C.
Published: January 2021

An outstanding challenge in developing a complete equation of state for materials at elevated pressure and temperature is a robust method of determining the bulk temperature state under dynamic conditions. In metals, the determination of bulk temperature states by optical pyrometry is complicated by the small optical depth and thermal conduction effects. These effects lead to observed temperatures differing by 20% or more from the bulk temperature state. In this work, we show the presence of thermal conduction effects in temperature measurements of tin and iron coatings during dynamic compression experiments. We demonstrate that tin, in contrast to iron, coatings can fail to converge to a bulk temperature source over the time scale of the experiment, requiring the experimenter to modify assumptions, design, or analysis. This work bounds thermal transport at shocked conditions.
Investigation on static grounding analysis model of non-pneumatic tire with nonlinear spokes
Authors: Liang Chen , Wei Wei , Mousavi Hoda , Chen Kun , Asafo-Duho Bentil , Wang Guolin
Published: January 2021

A static grounding analysis model of non-pneumatic tire (NPT) was built and presented in this paper. The proposed NPT analysis model considers the non-linearity of the spoke stiffness and is suitable for the performance exploration of various structures of the NPT. First, the shear band, rigid rim, and spoke structure of the NPT were simplified, the main structural parameters and mechanical parameters were extracted, and an analysis model was established. The model can describe the deformation of the NPT when it is subjected to external forces. On this basis, the different stiffness of the spokes during tension and compression was considered, an iterative method was used to compensate for the difference in the deformation caused by the difference in radial stiffness of the spokes, and an analysis model of NPT with nonlinear spokes was established. Then, the contact between the tire and the road surface was introduced to iteratively compensate for the reaction force of the road surface, and the deformation of the NPT with nonlinear spokes on the road surface was obtained. Finally, the finite element software ABAQUS was used to verify the accuracy of the model. This model contains more comprehensive structural parameters and material parameters, which can more realistically simulate the structural characteristics and static grounding behavior of the NPT.
Dynamics of enhanced neoclassical particle transport of tracer impurity ions in ion temperature gradient driven turbulence
Authors: Idomura Y. , Obrejan K. , Asahi Y. , Honda M.
Published: January 2021

Tracer impurity transport in ion temperature gradient-driven (ITG) turbulence is investigated using a global full-f gyrokinetic simulation including kinetic electrons, bulk ions, and low to medium Z tracer impurities, where Z is the charge number. It is found that in addition to turbulent particle transport, enhanced neoclassical particle transport due to a new synergy effect between turbulent and neoclassical transports makes a significant contribution to tracer impurity transport. Bursty excitation of the ITG mode generates non-ambipolar turbulent particle fluxes of electrons and bulk ions, leading to a fast growth of the radial electric field following the ambipolar condition. The divergence of E × B flows compresses up-down asymmetric density perturbations, which are subject to transport induced by the magnetic drift. The enhanced neoclassical particle transport depends on the ion mass because the magnitude of up-down asymmetric density perturbation is determined by a competition between the E × B compression effect and the return current given by the parallel streaming motion. This mechanism does not work for the temperature and, thus, selectively enhances only particle transport.
Strain-induced surface modalities in pnictogen chalcogenide topological insulators
Authors: Reid Thomas K. , Nayak Sanjeev K. , Alpay S. Pamir
Published: January 2021

We study the role of equi-biaxial strains on the electronic structure in pnictogen chalcogenides Bi2Se3, Bi2Te3, and As2Te3. Bi2Se3 and Bi2Te3 are topological insulators, and As2Te3 is an insulator with a relatively small bandgap. Based on the results of density functional theory calculations including van der Waals corrections, we demonstrate that a topological insulator (TI) state in As2Te3 can be induced by an epitaxial (in-plane) tensile misfit strain of 1%. Furthermore, we find overall that the effect of the misfit on the bandgap is larger for As2Te3 than for Bi2Se3 and Bi2Te3. We attribute this to a complex interplay between the misfit strain, spin–orbit coupling, and the relaxation of surface atomic layers. Our findings indicate that As2Te3 is more suitable than Bi2Se3 and Bi2Te3 for potential applications of strain-induced switching of TIs.
Unexpectedly large remanent polarization of Hf0.5Zr0.5O2 metal–ferroelectric–metal capacitor fabricated without breaking vacuum
Authors: Lee Younghwan , Alex Hsain H. , Fields Shelby S. , Jaszewski Samantha T. , Horgan Madison D. , Edgington Patrick G. , Ihlefeld Jon F. , Parsons Gregory N. , Jones Jacob L.
Published: January 2021

We introduce an Atomic Layer Deposition (ALD) technique referred to here as Sequential, No-Atmosphere Processing (SNAP) to fabricate ferroelectric Hf0.5Zr0.5O2 capacitors in Metal–Ferroelectric–Metal (MFM) structures. SNAP involves the ALD of each layer sequentially while maintaining the sample under vacuum process conditions without ambient exposure during the entire sequential deposition processes. We first use plasma enhanced ALD to fabricate 002-textured TiN films and study the degree of texture and quality of the film by X-ray Diffraction (XRD), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), and transmission electron microscopy. Building upon the textured TiN film, we fabricate MFM capacitors with 10-nm-thick Hf0.5Zr0.5O2 via SNAP deposition and observe an unexpectedly large remanent polarization (2Pr = 54.2 μC/cm2). We report that annealing at T <800 °C and at T = 800 °C results in different ferroelectric behaviors and phases determined by grazing incidence XRD patterns. We infer that the nonpolar tetragonal phase is dominant in films treated at T <800 °C, whereas the polar orthorhombic phase is dominant in films treated at T = 800 °C. Using ToF-SIMS and x-ray spectroscopy depth profiling on MFM capacitors, we observe an increase in the concentration of defects in the Hf0.5Zr0.5O2 layer after annealing. We believe that the absence of the native passive layer between Hf0.5Zr0.5O2 and TiN layers made via SNAP deposition is responsible for the unexpectedly large remanent polarization. In addition, we associate the 002-textured TiN as potentially playing a role in realizing the unexpectedly large remanent polarization.
Strain effects on band structure and Dirac nodal-line morphology of ZrSiSe
Authors: Rendy Bernardus , Hasdeo Eddwi Hesky
Published: January 2021

The Dirac nodal-line semimetals are new promising materials for technological applications due to their exotic properties, which originate from band structure dispersion and nodal-line behavior. We report strain effects on the band structure of ZrSiSe Dirac nodal-line semimetal through the density functional theory calculations. We found that the kz=0 Dirac nodal-line of ZrSiSe is robust to all strains under reasonable magnitude although there are significant changes in the band oscillation amplitude, bandgap, and band occupancy due to orbital interactions and the Fermi energy shift upon strains. We also found that the effective strains to tune the nodal-line and band structure are equi-biaxial tensile, uniaxial (100) tensile, and xz-plane shear strains.
Effective properties and eddy current losses of soft magnetic composites
Authors: Corcolle Romain , Ren Xiaotao , Daniel Laurent
Published: January 2021

This paper presents a semi-analytical homogenization model for Soft Magnetic Composites (SMCs), providing the effective magnetic behavior and the level of Eddy Current (EC) losses. Both linear and nonlinear magnetic behavior are considered. A magnetic circuit made of SMC is then modeled with a Finite Element Model (FEM). The size of heterogeneities of SMC being much smaller than the device size, the proposed approach relieves the burden of a very fine mesh in the FEM, by using the effective properties of an equivalent homogeneous material. The approach is validated by comparing the results on the homogenized magnetic circuit with the ones obtained from a computationally heavy FEM describing the heterogeneities with a very fine mesh. The results show that the homogenized model provides a very accurate description of the magnetic behavior and EC losses of SMC for both linear and nonlinear cases.
An adaptive coupled volume-of-fluid and level set method based on unstructured grids
Authors: Liu An , Sun Dongliang , Yu Bo , Wei Jinjia , Cao Zhizhu
Published: January 2021

This paper presents an adaptive coupled volume-of-fluid and level set (VOSET) method based on unstructured grids to simulate incompressible interfacial flows. In this study, a novel high quality refinement algorithm for unstructured grid cells based on level set and surface curvature is first developed to ensure a preset bandwidth of the adaptive region around the interface. Subsequently, the adaptive VOSET algorithm is integrated into a finite volume solver with a large-scale sparse matrix preconditioned bi-stable conjugate method. Finally, the accuracy and robustness of the current method are validated by four classical test cases: the dam break, single bubble rising, a Rayleigh–Taylor instability problem, and a liquid jet problem. It is found that the adaptive coupled VOSET algorithm makes the numerical results near the interface more accurate, especially the curvature and surface tension at corners. Moreover, the adaptive VOSET is more efficient since it reduces the number of grid cells significantly. The present results show that only 4.85%–24.5% of the number of adaptive grid cells and 5.31%–15.93% of the computational time are needed for VOSET compared to that of fixed unstructured grid cells, and thus, it has outstanding properties of both time and computational cost savings.
Asymptotic simplification for solutions of the energy critical nonlinear wave equation
Authors: Kenig Carlos E.
Published: January 2021

In this article, we survey recent results (with Duyckaerts and Merle) on the long-time behavior of radial solutions of the energy critical nonlinear wave equation in odd dimensions.
Controlling the number of discharge current pulses in an atmospheric dielectric barrier discharge by voltage waveform tailoring
Authors: Huang Zeen , Zhang Yuhui , Dai Dong , Wang Qiao
Published: January 2021

Atmospheric dielectric barrier discharges driven by tailored voltage waveforms are investigated numerically with a one-dimensional fluid model. We use the multi-frequency pulse-type voltage waveform as the control method and the harmonics N as the control parameter to control the number of discharge current pulses. The simulation results show that as N increases from 1 to 11, the number of discharge current pulses in each voltage half cycle (Np) decreases from 5 to 1, representing the transition from the multiple-current-pulse mode to the single-current-pulse (SCP) mode. In this process, both the current amplitude (Jpm) and the gap voltage of the first breakdown moment (Vgb) increase, and the efficiency of the plasma system can be improved by 5.6 times without reducing densities of reactive species. Further analysis reveals that the increase of Jpm is attributed to the variation in discharge current components, and the value of Vgb can be related to Np and the surface charge densities. Finally, an analytical method is proposed to estimate the minimum N to achieve the targeted SCP discharge. The results obtained in this work may contribute to the manipulation of power consumption and discharge stability in industrial applications.
The origin of interlayer-induced significant enhancement of EQE in CzDBA-based OLEDs studied by magneto-electroluminescence
Authors: Tang Xiantong , Pan Ruiheng , Zhu Hongqiang , Zhao Xi , Tu Linyao , Xiong Zuhong
Published: January 2021

Over twelve-fold enhancement of external quantum efficiency (EQE) is observed in 9,10-bis(4-(9H-carbazol-9-yl)-2,6-dimethylphenyl)-9,10-diboraanthracene (CzDBA)-based organic light-emitting diodes (OLEDs) with an interlayer between the hole-transporting layer (HTL) and the emission layer, where the CzDBA emitter is a typically donor–acceptor–donor (D–A–D)-type thermally activated delayed fluorescence material. Analyses of the fingerprint magneto-electroluminescence traces indicate that the interlayer ensures the charge balance of the emission layer in devices, avoiding triplet-charge annihilation and contributing to the enhancement of EQE. Additionally, experimental results also show that intersystem crossing (ISC) and reverse ISC (RISC) processes coexist in the device with an interlayer. Notably, ISC boosts with increasing bias currents and working temperatures, respectively, exhibiting abnormal current and normal temperature dependences. This abnormal phenomenon is caused by the weakened RISC between charge-transfer states of CzDBA molecules at large bias currents. More interestingly, as bias currents increase, ISC in the device without an interlayer first exhibits normal current dependences and then turns into an abnormal one, which may attribute to the competitive effects of exciplex at the HTL/CzDBA interface and excited states of CzDBA molecules. Our findings not only unravel the underlying mechanisms in D–A–D-type molecules but also provide ideas for designing highly efficient devices.
Microwave Hall effect measurement for materials in the skin depth region
Authors: Ogawa Ryo , Okada Tatsunori , Takahashi Hideyuki , Nabeshima Fuyuki , Maeda Atsutaka
Published: January 2021

We developed a new microwave Hall effect measurement method for materials in the skin depth region at low temperatures using a cross-shaped bimodal cavity. We analytically calculated electromagnetic fields in the cross-shaped cavity and the response of the cavity including the sample, whose property is represented by the surface impedance tensor; furthermore, we constructed the method to obtain the Hall component of the surface impedance tensor in terms of the change in resonance characteristics. To confirm the validity of the new method, we applied our method to measure the Hall effect in metallic Bi single crystals at low temperatures, and we confirmed that the microwave Hall angles coincide with the DC Hall angle. Thus, it becomes clear that the Hall angle measurement under cryogenic conditions becomes possible without any complicated tuning mechanisms, and our bimodal cavity method can be used to measure the microwave Hall effect on materials in the skin depth region. The result opens a new approach to discuss the Hall effect in condensed matter physics such as the microwave flux-flow Hall effect in superconductors.
Improving the quality factors of plasmonic silver cavities for strong coupling with quantum emitters
Authors: Bitton Ora , Gupta Satyendra Nath , Cao Yong , Vaskevich Alexander , Houben Lothar , Yelin Tamar , Haran Gilad
Published: January 2021

Plasmonic cavities (PCs) made of metallic nanostructures can concentrate electromagnetic radiation into an ultrasmall volume, where it might strongly interact with quantum emitters. In recent years, there has been much interest in studying such a strong coupling in the limit of single emitters. However, the lossy nature of PCs, reflected in their broad spectra, limits their quality factors and hence their performance as cavities. Here, we study the effect of the adhesion layer used in the fabrication of metal nanostructures on the spectral linewidths of bowtie-structured PCs. Using dark-field microspectroscopy, as well as electron energy loss spectroscopy, it is found that a reduction in the thickness of the chromium adhesion layer we use from 3 nm to 0.1 nm decreases the linewidths of both bright and dark plasmonic modes. We further show that it is possible to fabricate bowtie PCs without any adhesion layer, in which case the linewidth may be narrowed by as much as a factor of 2. Linewidth reduction increases the quality factor of these PCs accordingly, and it is shown to facilitate reaching the strong-coupling regime with semiconductor quantum dots.
Multi-scroll hidden attractor in memristive HR neuron model under electromagnetic radiation and its applications
Authors: Zhang Sen , Zheng Jiahao , Wang Xiaoping , Zeng Zhigang
Published: January 2021

This paper aims to propose a novel no-equilibrium Hindmarsh–Rose (HR) neuron model with memristive electromagnetic radiation effect. Compared with other memristor-based HR neuron models, the uniqueness of this memristive HR neuron model is that it can generate multi-scroll hidden attractors with sophisticated topological structures and the parity of the scrolls can be controlled conveniently with changing the internal parameters of the memristor. In particular, the number of scrolls of the multi-scroll hidden attractors is also associated with the intensity of external electromagnetic radiation stimuli. The complex dynamics is numerically studied through phase portraits, bifurcation diagrams, Lyapunov exponents, and a two-parameter diagram. Furthermore, hardware circuit experiments are carried out to demonstrate theoretical analyses and numerical simulations. From the perspective of engineering application, a pseudo-random number generator is designed. Besides, an image encryption application and security analysis are also performed. The obtained results show that the memristive HR neuron model possesses excellent randomness and high security, which is suitable for chaos-based real-world applications.
Compositional effect on auto-oscillation behavior of Ni100−xFex/Pt spin Hall nano-oscillators
Authors: Haidar M. , Mazraati H. , Dürrenfeld P. , Fulara H. , Ranjbar M. , Åkerman J.
Published: January 2021

We demonstrate the compositional effect on the magnetodynamic and auto-oscillation properties of Ni100−xFex/Pt (x = 10–40) nanoconstriction-based spin Hall nano-oscillators. Using spin-torque ferromagnetic resonance performed on microstrips, we measure a significant reduction in both damping and spin Hall efficiency with the increasing Fe content, which lowers the spin pumping contribution. The strong compositional effect on spin Hall efficiency is primarily attributed to the increased saturation magnetization in Fe-rich devices. As a direct consequence, higher current densities are required to drive spin-wave auto-oscillations at higher microwave frequencies in Fe-rich nanoconstriction devices. Our results establish the critical role of the compositional effect in engineering the magnetodynamic and auto-oscillation properties of spin Hall devices for microwave and magnonic applications.
Electro-viscoelasticity of agarose based electrorheological fluids
Authors: Dhar Purbarun , Saini Vimal , Chattopadhyay Ankur , Samanta Devranjan
Published: January 2021

In this article, we report a new class of colloidal, micrometer-scale agarose powder based organic electrorheological (ER) fluids and its ER and viscoelastic characteristics. The steady shear ER characteristic of the colloids shows enhancements in the yield stress of the fluid, and yield stress values approaching ∼1 kPa have been noted. The ER hysteresis and electro-thixotropy illustrate that the microstructure of the colloids under field effects is able to withstand dynamic and impact stresses with good repeatability. The electro-creep strain and stress relaxation characteristics of the colloids show transition to the elastoviscous state with an increase in electric field strength. The oscillatory shear ER characteristic of the colloids shows field induced transition from a fluid-like nature to solid-like nature. Atypical regimes of loss and regain in viscoelastic nature are noted for the colloids under different field constraints. The viscoelastic dissipation and complex viscosity characteristics are also discussed for utilitarian aspects. Mathematical analysis reveals that the electric field induced viscoelastic, creep strain, and stress relaxation signatures of the colloids conform to fractional derivative elastoviscous models. The present findings may find significant implications toward the design and development of organic particle based ER fluids.
Precession coupled spin current in spin torque driven magnetic tunnel junctions
Authors: Sun Jonathan Z.
Published: January 2021

A spin-torque switchable magnetic tunnel junction contains two ferromagnetic electrodes across a barrier that supports spin-polarized tunnel current. The spin-torque induced magnetic switching of its more agile, or “free” layer provides the “write” mechanism. Often the dynamics of the non-switching “reference” layer is also important. Here, we illustrate such dynamics involving both the free and the reference layers by using an exchange-coupled two-macrospin-moment numerical model, described by a set of Landau–Lifshitz–Gilbert (LLG) equations, together with a stochastic Langevin-field for finite temperature. Damping-like spin-transfer torque is included for both moments. In steady-state, the coupled precession is shown to reduce effective spin-current delivered to the free layer due to a precessional resonant spin-current back flow. This back-flow of spin current preferentially affects the parallel state dynamics. It is not directly related to the reference layer’s thermal stability, nor its spin-torque switching threshold, as determined by the total anisotropy energy and magnetic volume. Rather, the spin-current reduction relates primarily to the matching of precession frequency between the free- and the reference-layer. Therefore, a desirable materials choice is to avoid anisotropy fields giving the free and the reference layer similar dynamic frequencies, so as to prevent such resonance-related spin-current loss.
Equilibrium configurations in a magnetic fluid-based field mapping and gas pressure measuring system: Experiment and simulations
Authors: Ryapolov P. A. , Sokolov E. A. , Bashtovoi V. G. , Reks A. G. , Postnikov E. B.
Published: January 2021

In this work, we present a measurement system based on the thin layer of magnetic fluid aimed at scanning either the non-uniform magnetic field distribution applicable for magnetic levitation systems (MagLev) or determining small excess gas pressure. The key idea is based on the photo registration of a transparent air-filled cavity formed in a thin magnetic fluid layer due to balancing the gas pressure and the pressure emerging due to magnetic forces. As a result, the contour of the magnetic field lines in 3D space is visible. It is shown that the theoretical analysis and numerical simulations are consistent with experimental results.