bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of magnetotherapy on various systems of the body and on the process of wound healing in children with cleft lip and palate
Authors: Mirzaeva Feruza , Yadgarova Gulnara , Kamalova Feruza
Published: July 2024

In this article we present the results of magnetic therapy on the wound healing process in children with cleft lip and palate after cheiloplasty surgery. At the same time, there is an improvement in metabolic processes in tissues, which contributes to their proper nutrition and restoration.Inflammation and associated soft tissue swelling are eliminated. Locally, blood vessels dilate and blood supply improves. The pain is relieved.Magnetotherapy is a method of physiotherapy that uses magnetic fields of varying strengths and frequencies for the treatment, rehabilitation or prevention of diseases. To carry it out, stationary and portable devices have been developed. The principle is simple: one or more electromagnetic applicators are installed on certain areas of the body, or the patient is placed in a large-diameter magnetic chamber or on a special mattress. The method is based on the fact that a magnetic field affects electrically charged particles moving in the human body. They are found in biological fluids - blood, lymph, cytoplasm of cells. Under the influence of a magnet, weak electric currents arise in these environments. They cause many responses: metabolism, blood properties, the speed of transmission of nerve impulses change, microcirculation and the delivery of oxygen and micronutrients improve. This leads to the following effects: reduction of tissue swelling, suppression of the inflammatory process, local anesthesia, reduction of blood viscosity, normalization of blood pressure, acceleration of healing and tissue restoration, stimulation of the immune system.
Immunological predictors in predicting premature birth
Authors: Sarkisova Lyalya , Karimova Nilufar , Hikmatova Nigina , Shodiev Botur , Kadyrbayeva Madina , Suleymanova Gulrukh
Published: July 2024

In accordance with the purpose and objectives of this study, we studied the course of pregnancy and childbirth in 200 women at a gestational age of 22-36 weeks. The main group consisted of 65 women with a threatened miscarriage, 40 women with preterm labor without amniotic fluid and 45 women with amniotic fluid, the control group consisted of 50 women with a physiological course of pregnancy. Immunological studies were carried out in the immunological laboratory of the Specialized Research Republican Center for Obstetrics and Gynecology.
Take-away and sit-down service operations under inequity aversion
Authors: Zeng Sijia , Hu Wei , Sun Xiaochen
Published: July 2024

Profit contributed by take-away service has become an increasingly essential element of the restaurant operating revenue. Since take-away service usually relies on the third-party platform and there are many differences between the cost of take-away service and that of sit-down service. We focus on the restaurant which provides both sit-down service and take-away service, the service system is modeled as a two-stage tandem queueing system. We study the restaurant’s optimal capacity level for each stage. Besides, as there exist price/waiting time difference between the two services, inequity aversion is also investigated in our model. We study symmetrical and asymmetrical inequity aversion. We find that the optimal service capacity consists of two parts, base capacity and safety capacity. And the loss resulted from waiting time lag is equal to the waste of resources caused by fluctuations in arrival rate. Further, when customers really long for the restaurant, even if high price will lead to severe inequity aversion, restaurant can always earn more by raising the price in service channel with high revenue. While when customers are indifferent of the restaurant and the others, the price gap is meant to result in revenue decrease. In addition, reduction in customers’ susceptibility can help to enhance operation profit in general. Market environment plays a decisive role in choosing the optimal service level.
Stationsäquivalente Behandlung (StäB) gerontopsychiatrischer
Patienten in einer deutschen Großstadt – Eine Beobachtungsstudie
Authors: Couturier Samuel Paul , Spielmann-Benson Gloria , Frölich Lutz , Hausner Lucrezia
Published: July 2024

Zielsetzung Patientencharakterisierung und Evaluation der
gerontopsychiatrischen Stationsäquivalenten Behandlung (StäB-G) in einer
deutschen Großstadt.

Methoden Erhebung von soziodemographischen und klinischen Daten, sowie
Erfassung von klinischem Schweregrad (CGI), gesundheitlicher und sozialer
Funktionsfähigkeit (HoNOS-D) und der autonomen Durchführung von Aktivitäten des
täglichen Lebens (IADL) zu Beginn und Ende der StäB-G.

Ergebnisse Es wurden 53 Patienten (Alter: MW=74,81, SD=7,88; 77,4% Frauen)
analysiert. Psychiatrische Hauptdiagnosen waren affektive Störungen (n=25),
Schizophrenie und schizotype Störungen (n=20). 12 Patienten (22,64%) wiesen eine
kognitive Störung auf. CGI, HoNOS-D und IADL zeigen eine signifikante
Verbesserung über die Behandlungszeit (gepaarter t-Test, p<0,001).

Schlussfolgerung In einer städtisch-geprägten gerontopsychiatrischen
Population ist StäB-G gut implementierbar. Symptomschwere, soziale
Funktionsfähigkeit und Autonomie verbesserten sich signifikant.
A Medical Student-Led Multipronged Initiative to Close the Digital Divide in Outpatient Primary Care
Authors: Jiangliu Yilan , Kim Hannah T. , Lazar Michelle , Liu Eileen , Mantri Saaz , Qiu Edwin , Berube Megan , Sood Himani , Walia Anika S. , Biondi Breanne E. , Mesias Andres M. , Mishuris Rebecca , Buitron de la Vega Pablo
Published: July 2024

Background The coronavirus disease 2019 pandemic accelerated the use of telehealth. However, this also exacerbated health care disparities for vulnerable populations.

Objectives This study aimed to explore the feasibility and effectiveness of a medical student-led initiative to identify and address gaps in patient access to digital health resources in adult primary care clinics at an academic safety-net hospital.

Methods Medical students used an online HIPAA-compliant resource directory to screen for digital needs, connect patients with resources, and track outcome metrics. Through a series of Plan-Do-Study-Act (PDSA) cycles, the program grew to offer services such as information and registration for subsidized internet and phone services via the Affordable Connectivity Program (ACP) and Lifeline, assistance setting up and utilizing MyChart (an online patient portal for access to electronic health records), orientation to telehealth applications, and connection to community-based digital literacy training.

Results Between November 2021 and March 2023, the program received 608 assistance requests. The most successful intervention was MyChart help, resulting in 83% of those seeking assistance successfully signing up for MyChart accounts and 79% feeling comfortable navigating the portal. However, subsidized internet support, digital literacy training, and telehealth orientation had less favorable outcomes. The PDSA cycles highlighted numerous challenges such as inadequate patient outreach, time-consuming training, limited in-person support, and unequal language assistance. To overcome these barriers, the program evolved to utilize clinic space for outreach, increase flier distribution, standardize training, and enhance integration of multilingual resources.

Conclusion This study is, to the best of our knowledge, the first time a medical student-led initiative addresses the digital divide with a multipronged approach. We outline a system that can be implemented in other outpatient settings to increase patients' digital literacy and promote health equity, while also engaging students in important aspects of nonclinical patient care.
Consumer liability and firm responsiveness: evidence from automobile recalls
Authors: Majid Kashef Abdul , Bapuji Hari
Published: July 2024

Regulations for product recalls differ internationally. In some countries, the responsibility rests entirely with manufacturers to quickly take corrective measures to ensure consumer safety. In other countries, penalties may also be imposed on consumers who persist in using products that have been recalled. We hypothesize that firm responsiveness (as measured by the time between the product release and the recall) will be higher in markets where product safety regulations that include consumer liability than in markets where product safety regulations focus solely on firms, and that firms that standardize their vehicles across such markets become more responsive in both those markets. We test our hypotheses using data on 569 automobile recalls issued during 2003 to 2019 in four different markets (the US, Australia, Germany, and the UK) that differ in their regulatory focus. Our empirical examination using survival analysis techniques with an accelerated failure time model confirms that the time to recall is shorter in countries that include consumer liability and for standardized vehicles that are sold across countries that include and exclude consumer liability.
Design of a real-time frequency stabilization system for dual laser-based interferometer on EAST
Authors: Wang Y. , Yao Y. , Liu H. Q. , Zhang Y. , Zhang J. M. , Jie Y. X. , Zou Z. Y.
Published: July 2024

This study addresses the challenge of intermediate frequency (IF) instability in the far-infrared polarimeter/interferometer (POINT) of the Experimental Advanced Superconducting Tokamak (EAST) to ensure the accuracy and stability of electron density measurements. Sudden and extensive IF shifts of the lasers can cause instability and even measurement errors of the diagnostic system. This paper introduces a comprehensive solution for stabilizing IF fluctuations. First, analog IF is converted into digital form using an analog-to-digital converter, and the digitalized signal is processed by a digital signal system based on a ZYNQ processor. The exact value of the IF is obtained by acquiring the point of maximum amplitude through the fast Fourier transform method, while the ZYNQ processor loaded with a fuzzy control algorithm will precisely adjust the laser cavity length via piezoelectric ceramics, achieving frequency stabilization within a target range. Comparative analyses confirm the method’s efficacy in managing sudden frequency shifts, maintaining stability within 850 ± 100 kHz (a central frequency of 850 kHz, fluctuating within a range of ±100 kHz), with a control speed of 0.5 s per action and robust against variations up to 270 kHz. This efficient and rapid control mechanism fulfills the critical need for IF stabilization, ensuring the stability and precision of the POINT system in the EAST discharge experiments.
A simple recipe for designing multicomponent ultra-high temperature ceramic classes by using structure maps coupled with machine learning
Authors: Mitra Rahul , Gupta Anubhav , Biswas Krishanu
Published: July 2024

Successful synthesis of novel high entropy ceramic (HEC) for ultra-high temperature application classes, namely, borides, carbides, and nitrides, has been experiencing a bottleneck in having a suitable design and successful synthesis strategy. Producing high-entropy ultra-high-temperature ceramics from their oxides offers a major processing benefit, while employing a design approach using machine learning enhances the efficiency of the formation of single-phase HECs. In this regard, we propose a generalized strategy to generate a semi-synthetic database for each of these classes using literature data and atomic environment mapping-based structure plots, which can further be used to build machine learning models. The imbalance of the dataset was addressed using adaptive synthetic sampling and the edited nearest neighbors technique. The trained models are able to accurately predict over 90% of the single-phase chemistry for each of the classes. Furthermore, a few compositions representing these classes were successfully synthesized from the corresponding oxide mixture to validate the effectiveness of the proposed strategy.
Frictional aging in microscale structural superlubric graphite contacts
Authors: Huang Yisheng , Ma Ming , Peng Deli , Tian Kaiwen
Published: July 2024

Devices based on structural superlubricity (SSL) technology are characterized by energy efficiency, low wear, longevity, and superior performance. However, the ubiquitous phenomenon of frictional aging, where static friction increases with contact time, can lead to issues such as startup failure and return-to-origin failure in SSL devices. To date, frictional aging in SSL systems has not been studied. This paper delves into the frictional aging behavior of SSL graphite systems. Our research reveals that microscopic graphite flakes in contact with various substrate materials, including silicon, exhibit significant frictional aging from 1 to 100 s of contact time. The static friction of graphite–silicon pairs logarithmically increases with contact time and remains constant or decreases with load. Furthermore, by comparing static friction values of graphite flakes in contact with small silicon mesas and silicon flat area, we decoupled the contributions to the total static friction from the edges and in-plane area of the contact and found that in-plane contributions could be close to or even larger than edge contributions, challenging the traditional belief that friction of a graphite flake is dominated by the edges. These results enrich the basic understandings of structural superlubricity, lay the foundation for developing techniques to effectively mitigate edge effects, and provide important references for the design of future SSL devices.
How numerical simulations helped to achieve breakeven on the NIF
Authors: Marinak M. M. , Zimmerman G. B. , Chapman T. , Kerbel G. D. , Patel M. V. , Koning J. M. , Sepke S. M. , Chang B. , Schroeder C. R. , Harte J. A. , Bailey D. S. , Taylor L. A. , Langer S. H. , Belyaev M. A. , Clark D. S. , Gaffney J. , Hammel B. A. , Hinkel D. E. , Kritcher A. L. , Milovich J. L. , Robey H. F. , Weber C. R.
Published: July 2024

The inertial confinement fusion program relies upon detailed simulations with inertial confinement fusion (ICF) codes to design targets and to interpret the experimental results. These simulations treat as much physics from essential principles as is practical, including laser deposition, cross beam energy transfer, x-ray production and transport, nonlocal thermal equilibrium kinetics, thermal transport, hydrodynamic instabilities, thermonuclear burn, and transport of reaction products. Improvements in radiation hydrodynamic code capabilities and vast increases in computing power have enabled more realistic, accurate 3D simulations that treat all known asymmetry sources. We describe how numerical simulations helped to guide the program, assess the impediments to breakeven, and optimize every aspect of target design. A preshot simulation of the first National Ignition Facility experiment that surpassed breakeven predicted an increased yield that matches the experimental result, within the preshot predicted uncertainty, with a target gain of 1.5. We will cover the key developments in Lawrence Livermore National Laboratory ICF codes that enabled these simulations and give specific examples of how they helped to guide the program.
Oxygen vacancy engineering in Si-doped, HfO2 ferroelectric capacitors using Ti oxygen scavenging layers
Authors: Barrett N. , Hamouda W. , Lubin C. , Laguerre J. , Carabasse C. , Vaxelaire N. , Coignus J. , Martin S. , Grenouillet L.
Published: July 2024

In this paper, the ferroelectric properties of TiN/Ti/Si:HfO2/TiN stacks are shown to be modulated by the Ti oxygen scavenging layer, leading to improved remanent polarization and wake-up at low switching fields. Hard x-ray photoelectron spectroscopy is used to measure the oxygen vacancy (VO) concentration in Si-doped HfO2 based capacitors. This VO engineered ferroelectric stack is then assessed at the wafer scale within 16 kbit 1T-1C FeRAM arrays integrated into 130 nm CMOS. The introduction of a Ti oxygen scavenging layer at the top interface of Si:HfO2-based BEOL-integrated metal/ferroelectric/metal capacitors enhances their ferroelectric (FE) behavior (+100% remanent polarization 2.Pr), confirming the positive role of modest concentrations of VO in orthorhombic phase crystallization at low thermal budgets. It is statistically demonstrated at 16 kbit array level that VO-rich FE Si:HfO2 facilitates 2.5 V FeRAM array operation with improved memory window. The field cycling dependence of the memory window is correlated with the VO concentration, and an endurance of 108 cycles is measured at the array level.
Pressure-tuned superflat bands and electronic localization in twisted bilayer graphene-like materials
Authors: Wang Hongfei , Lei Dangyuan
Published: July 2024

Electronic properties of twisted bilayer graphene-like materials can be modified substantially by manipulating twist angles, allowing for many exotic correlated phenomena. However, typical moiré flatbands holding these phenomena only appear with specific small twist angles. Here, we report a class of pressure-tuned superflat bands and localized electronic states over a wide range of twist angles, beyond the physics of twisted bilayer graphene near the Fermi energy. Under the slowly varying lattice distortion approximation, localized electronic states deterministically emerge in isolation at the edge of bulk spectra and are spatially centered around the AA stacked region, governed by macroscopic effective potential wells of moiré superlattices. Moreover, as macroscopic effects, pressure-tuned superflat bands and localized electronic states exhibit excellent stability against small perturbations. Our results suggest that applying pressure in generic twisted bilayer graphene-like materials may evoke widespread electronic correlations, providing opportunities for exploring electronic interactions and superconductivity.
Broadband acoustic absorption at low frequencies by slabs and clusters made of hard cylindrical rods
Authors: Ibarias Martin , Cutanda Henríquez Vicente , Lucklum Frieder , Sánchez-Dehesa José
Published: July 2024

Within the low-frequency limit, this work analyzes the viscous absorbing properties of circular clusters and semi-infinite slabs made of rigid scatterers embedded in a fluid, such as air or water. These structures are made of rigid scatterers distributed in a hexagonal lattice, and they are proposed as useful absorbing devices in the core of acoustic black holes or acoustic metasurfaces. It is demonstrated that in both types of structures, an optimum value of the filling fraction produces the maximum absorption in a given frequency band. To avoid heavy numerical simulations, the broadband absorbing power has been obtained using a homogenization theory providing not only the effective acoustic parameters (effective mass and effective sound speed) but also the decay coefficient due to viscosity. An enhancement of the broadband sound absorption can be obtained by using a refractive index gradient allowing an increase of the acoustic energy into the semi-infinite slabs. The theoretical predictions are well supported by numerical simulations based on the finite-element and boundary-element methods, respectively, for the semi-infinite slabs and clusters. These predictions have potential applications in the design of structures and metasurfaces with enhanced absorbing power at low frequencies. The analytical model is further supported by experiments made with a 3D-printed sample.
Cavitation flow characteristics on the surface of hydrofoil with microjet structure
Authors: Gu Yunqing , Qiu Qianfeng , Ren Yun , Ma Longbiao , Wu Denghao , Mou Jiegang , Wu Zhenxing , Dai Dongshun
Published: July 2024

A hydrofoil physical model is established based on the surface microstructure to mitigate the detrimental effects of cavitation phenomena on hydrodynamic machinery, such as cavitation erosion or surface damage. Tangential microjet structures are arranged on the hydrofoil's surface, and the modified k-omega shear stress transport (SST k–ω) turbulence model is employed to simulate the hydrofoil numerically. This simulation aims to analyze the effects of different chordwise positions and widths of microjet structures on the cavitation flow and performance of hydrofoils. The mechanism of cavitation suppression is revealed by coupling the chordwise position and width of the microjet structures. The results indicated that the chordwise position of the microjet structures near the trailing edge of the hydrofoil has a minimal impact on the hydraulic properties. The optimal chordwise positions are 0.5c and 0.6c, with the deviation rate of the lift-drag ratio within 3%. The optimum jet width is 0.5 mm, and the cavitation suppression is approximately 15% of the prototype hydrofoil. The microjet structures with tangential jets suppress cavitation by creating obstruction and suppression of the re-entrant jet. The tangential jet ratio of 0.3 represents the most effective tangential jet hydrofoil scheme, and the addition of tangential jets produces a significant inhibitory effect on the shedding of large-scale cavitation.
A comparison of two piezoelectric actuator concepts for fast mechanical switching in DC hybrid circuit breakers
Authors: Al-Dweikat Mohmmad , Zhang Guogang , Liu Yu , Jian Cui
Published: July 2024

Amplified piezoelectric actuators have gained considerable attention due to their inherent advantages, including rapid response, reliability, and efficiency, making them promising candidates for Direct Current (DC) switching applications. They can operate in two distinct operational modes: Block–Free (B–F) and Free–Free (F–F) configurations. These two modes offer diverse mechanical constraints and are chosen based on the application’s specific requirements. This study aims to present a comparative assessment between the two modes to evaluate each configuration’s applicability in DC fast switching. Accordingly, the principle behind each actuation scheme was illustrated, and both designs were modeled and analyzed by the finite element method. Subsequently, two prototypes were assembled, each resembling a different operational mode. The established prototypes were then subjected to actuation and interruption tests to investigate their travel and switching performances. Comparative results revealed that while block–free could deliver a higher apparent stroke, the accumulated gap for each configuration is almost the same. Both actuators demonstrated high capability when utilized as actuation units for fast vacuum mechanical switches integrated into a hybrid circuit breaker for DC interruption. However, the free–free operation excelled in terms of fast response, as it managed to clear the mimicked fault current faster than the block–free configuration.
The effect of activated water on lentil seed germination utilizing several plasma reactors and a hydrogen injection system
Authors: Mansory S. , Bahreini M.
Published: July 2024

As a threat to meeting the global demand for food created by the continued growth of population, different methods are being applied to enhance seed germination and plant growth. This study investigates the effect of hydrogen-rich water (HRW) and different plasma-activated waters (PAW) and their combinations including HRW, PAW1, PAW2, HPAW1, and HPAW2 on the seed germination of lentils. Different arc discharge reactors are generated under atmospheric pressure in the air. Optical emission spectroscopy was used to detect the radiative species formed in the plasma zone. Raman spectra and physicochemical properties of different waters were investigated. The results demonstrated significant differences in the properties of different activated waters compared to control water. On day 3 after treatment, the fraction and length of germinated seeds were evaluated. During germination, treated water significantly increased germination parameters such as final germination percentage, mean germination time, germination index, and coefficient of germination velocity. HPAW2 exhibited the highest germination index (GI), which combines germination percentage and speed. The plasma systems also effectively reduced the pH of PAW1 and PAW2, with a greater decrease observed in HPAW1 and HPAW1. Analysis of nitrite and nitrate levels revealed that HPAW2 had the highest concentrations, indicating more reactive processes in the presence of hydrogen. Based on our results, it can be concluded that lentil seed germination can be increased using PAW and hydrogenated PAW combined.
Resolvent expansions of 3D magnetic Schrödinger operators and Pauli operators
Authors: Jensen Arne , Kovařík Hynek
Published: July 2024

We obtain asymptotic resolvent expansions at the threshold of the essential spectrum for magnetic Schrödinger and Pauli operators in dimension three. These operators are treated as perturbations of the Laplace operator in L2(R3) and L2(R3;C2), respectively. The main novelty of our approach is to show that the relative perturbations, which are first order differential operators, can be factorized in suitably chosen auxiliary spaces. This allows us to derive the desired asymptotic expansions of the resolvents around zero. We then calculate their leading and sub-leading terms explicitly. Analogous factorization schemes for more general perturbations, including e.g. finite rank perturbations, are discussed as well.
Enhancement of spin Hall angle in semimetallic materials
α
-Sn under voltage regulation
Authors: Zha Xi , Lu Qi , Liu Jiaqiang , Liang Liwen , Zhao Yifan , Peng Bin , Liu Ming
Published: July 2024

Utilizing current-induced spin–orbit torque (SOT) to control magnetization is essential for the advancement of spintronics. SOT offers high energy efficiency and rapid operation speed. The ideal SOT material should have a high charge-to-spin conversion efficiency and excellent electrical conductivity. Recently, there has been a focus on topological insulator materials with topological surface states in SOT research due to their controllability in spin–orbit coupling, conductivity, and energy band topology. While topological Dirac semimetallic materials show promise for SOT applications, research on voltage regulation of their spin Hall angle is still in its early stages. This paper investigates the multilayer structure of a Dirac semimetallic material. In an α-Sn/Ag bilayer, the voltage regulation effect can increase the spin Hall angle by five times by adjusting the strain on the Fermi level. Experiments explore the role of a silver layer as a transport layer in the electric field control of multilayer films. This material system can enhance its effects under electric field regulation and offer insight for achieving regulation in new spintronic devices.
Numerical investigation on effects of damping ratio for flow-induced vibration of tandem cylinders
Authors: Chen Jingqian , Cai Haopeng , Li Xiaochen , Li Xiaoming , He Linghui
Published: July 2024

This study numerically investigates the effects of damping ratios on flow-induced vibration (FIV) of two-degree-of-freedom elastically mounted tandem cylinders. By setting the tandem spacing between cylinder centers to four cylinder diameters, the FIV problem was solved using the two-dimensional unsteady Reynolds-averaged Navier–Stokes equations and the shear stress transport k−ω turbulence model. Four typical damping ratios of 0.0036, 0.036, 0.198, and 0.36 are employed to explore the effects of damping ratios on the FIV response. Simulation results show that the peak transverse amplitudes and the fluid force coefficients of cylinders generally decrease with increasing damping ratios. Owing to the presence of lock-in region in the streamwise vibration of the downstream cylinder for ζ=0.36, its streamwise vibration amplitude is larger than those for the damping ratio ζ=0.198 when the reduced velocity Ur≥8. With the increase in damping ratios, trajectories of the downstream cylinder become more regular. It is found that the damping ratio has little impact on the frequency capture phenomenon in the cross-flow direction, while the frequency capture phenomenon is first discovered in the in-line direction, which depends on the damping ratio. A transition in the vortex shedding mode is observed as the damping ratio increases. The increase in damping ratio contributes to the stabilization of energy transfer. It is suggested that damping ratios play a significant role in the FIV responses of tandem cylinders.
Time evolution as an optimization problem: The hydrogen atom in strong laser fields in a basis of time-dependent Gaussian wave packets
Authors: Schrader Simon Elias , Kristiansen Håkon Emil , Pedersen Thomas Bondo , Kvaal Simen
Published: July 2024

Recent advances in attosecond science have made it increasingly important to develop stable, reliable, and accurate algorithms and methods to model the time evolution of atoms and molecules in intense laser fields. A key process in attosecond science is high-harmonic generation, which is challenging to model with fixed Gaussian basis sets, as it produces high-energy electrons, with a resulting rapidly varying and highly oscillatory wave function that extends over dozens of ångström. Recently, Rothe’s method, where time evolution is rephrased as an optimization problem, has been applied to the one-dimensional Schrödinger equation. Here, we apply Rothe’s method to the hydrogen wave function and demonstrate that thawed, complex-valued Gaussian wave packets with time-dependent width, center, and momentum parameters are able to reproduce spectra obtained from essentially exact grid calculations for high-harmonic generation with only 50–181 Gaussians for field strengths up to 5 × 1014 W/cm2. This paves the way for the inclusion of continuum contributions into real-time, time-dependent electronic-structure theory with Gaussian basis sets for strong fields and eventually accurate simulations of the time evolution of molecules without the Born–Oppenheimer approximation.
Sign reversal and symmetry change of anisotropic magnetoresistance in antiferromagnetic LSMO films
Authors: Li Ruikang , Jin Chao , Bai Haili
Published: July 2024

The study of anisotropic magnetoresistance (AMR) holds dual significance in both theoretical and applied contexts. The underlying mechanisms of AMR remain unclear, and the phenomenon of AMR sign reversal (positive and negative transitions in values) has garnered multiple interpretations, demanding experimental verification. In this work, the effect of epitaxial strain on magnetic and transport properties of perovskite manganese oxide La0.35Sr0.65MnO3 films is investigated. The AMR demonstrates sign reversal and symmetry change behaviors. The symmetry changes of AMR stem from the competition between Zeeman energy, exchange interaction energy, and magnetocrystalline anisotropy energy. The sign reversal of AMR is attributed to the change in the density of states of spin up and spin down of conduction electrons during the magnetic phase transition induced by epitaxial strain. Our work offers experimental evidence and a reasonable explanation for the origin of the sign reversal of AMR.
The role of intersystem crossing in the reactive collision of S+(4S) with H2
Authors: Zanchet Alexandre , Roncero Octavio , Karabulut Ezman , Solem Nicolas , Romanzin Claire , Thissen Roland , Alcaraz Christian
Published: July 2024

We report a study on the reactive collision of S+(4S) with H2, HD, and D2 combining guided ion beam experiments and quantum-mechanical calculations. It is found that the reactive cross sections reflect the existence of two different mechanisms, one being spin-forbidden. Using different models, we demonstrate that the spin-forbidden pathway follows a complex mechanism involving three electronic states instead of two as previously thought. The good agreement between theory and experiment validates the methodology employed and allows us to fully understand the reaction mechanism. This study also provides new fundamental insights into the intersystem crossing process.
Deep learning accelerated numerical simulation for three-dimensional compressible fluids
Authors: Zhang Meina , Cui Qingjie , Xiao Min , Ni Guoxi
Published: July 2024

Numerical simulation of fluid flow is a long-standing challenge across many physical application domains, including engineering, climate, and the physical science. There has been a surge of interest in high order schemes aimed at improving simulation accuracy on coarse grids. However, for high-dimensional fluids, the computational cost escalates with the number of dimensions involved. In this paper, we propose a deep learning-based approach to accelerate the numerical computation and further improve the accuracy in simulating three-dimensional (3D) compressible fluids which can be described by Eulerian equations. The proposed work utilizes 3D Euler transformer networks to learn the interpolation coefficients for cell boundaries, which are applied to approximate the boundary fluxes of fluid on coarser grids. Benefiting from learning features of high-resolution fluid flow, our learned interpolation method yields finer performance on coarse grids, thereby accelerating the fluid simulations and improving the numerical accuracy. The numerical experiments confirm that the proposed method improves performance in inference of coarse-grained dynamics.
Flow characteristic investigation of localized arc filament plasma assisted turbulent jet and Bunsen flame
Authors: Chen Xiuxiu , Chen Fang , Meng Yu , Chen Yuhuang , Zheng Yutao , Xu Leilei
Published: July 2024

Localized arc filament plasma actuators (LAFPAs) have shown the capability to alter the entrainment of freestream air into a jet. This paper presents an investigation into the effects of LAFPAs on the air jet and methane/air premixed Bunsen flames at different Reynolds numbers. The flow disturbance covering the laminar to turbulent transient conditions was generated by a high voltage plasma discharge system of LAFPAs. The high speed Z-type Schlieren technique was applied to visualize the instantaneous flow and flame structures, and an optical flow algorithm was used to estimate the velocity distribution and further analyze the turbulent effect induced by the plasma. The results illustrate that, in the presence of LAFPA operation, the turbulence jet was accelerated and the jet mixing enhanced. Meanwhile, with the help of LAFPAs, the global consumption burning velocity increased significantly by the area enhancement via plasma–flame interaction. The flame front response to the flow disturbance consists of more surface stretch and flame separation. Furthermore, turbulence spectra analysis of the images reveals a considerable increase in turbulent fluctuations in both cold flow and reacting flow.
Nature of instability in flow-driven porous anodic oxide
Authors: Wankhede Sajal , Pillai Dipin S.
Published: July 2024

Self-organized porous anodic oxide films are formed by the electrochemical oxidation of reactive metal aluminum in acidic solutions in which the oxide is soluble. Recently, viscous flow models have shown using linear stability analysis that the instability results from a trade-off between the destabilizing effect of viscous flow of oxide and the stabilizing effect of oxide formation, which provides the wavelength selection mechanism for pattern formation. Anion adsorption on surface growth sites causes nonuniform compressive stress at the oxide–solution interface, which drives the flow. This anodic instability is analogous to the classical Marangoni instability induced by surface tension gradients. In this work, nature of the instability beyond the stability threshold is determined using a weakly nonlinear analysis. For the growth of well-developed pores beyond the threshold, a subcritical nature of the instability is essential. However, our weakly nonlinear analysis shows that the solutions emerging from neutral stability are supercritical in nature at all wavenumbers for the practical range of anodizing control parameters investigated. We also determine the region where the model is Hadamard stable, a necessary condition for well-posedness.
Unusual dynamics of tetrahedral liquids caused by the competition between dynamic heterogeneity and structural heterogeneity
Authors: Lee Shao-Chun , Z Y
Published: July 2024

Tetrahedral liquids exhibit intriguing thermodynamic and transport properties because of the various ways tetrahedra can be packed and connected. Recently, an unusual temperature dependence of the stretching exponent β in a model tetrahedral liquid ZnCl2 from Tm + 85 K to Tm + 35 K has been reported using neutron-spin echo spectroscopy. This discovery stands in sharp contrast to other glass-forming liquids. In this study, we conducted neural network force field driven molecular dynamic simulations of ZnCl2. We found a non-monotonic temperature dependence of β from liquid to supercooled liquid temperatures. Further structural decomposition and dynamic analysis suggest that this unusual dynamic behavior is a result of the competition between the decrease in the diversity of tetrahedra motifs (structural heterogeneity) and the increase in glassy dynamic heterogeneity. This result may contribute to new understandings of the structural relaxation of other network liquids.
Hydrothermal synthesis of tetragonal FeS: Dome-shaped superconductivity vs Fe:S actual molar ratios
Authors: Xie Wen , Zheng Fei , Xu Han-Shu
Published: July 2024

We successfully synthesized tetragonal FeS with various Fe:S molar ratios using a hydrothermal method, and the EDS and XRF results confirmed that FeS exhibits superconductivity within the Fe and S element ratio range of 1.155–1.274, rather than a strict stoichiometric ratio. The reaction temperature can not only play a crucial role in determining the purity of the obtained FeS phase but also significantly alter its micromorphology. Significantly, by analyzing the relationship between the Fe:S actual molar ratio and Tc as well as the Fe:S actual molar ratio and unit cell volume, FeS exhibits dome-shaped superconductivity and shows a negative correlation with Tc and chemical pressure. Furthermore, considering the correlation between anion height (hanion) and Tc, Tc reaches the maximum value of 4.53 K for hanion ≈ 1.28 Å, a behavior distinct from that of observed in Fe-pnictide superconductors. In short, our experimental results provide a unique perspective to deepen our understanding of FeS superconductors.
Microstructure and reflectance of porous GaN distributed Bragg reflectors on silicon substrates
Authors: Ghosh S. , Sarkar M. , Frentrup M. , Kappers M. J. , Oliver R. A.
Published: July 2024

Distributed Bragg reflectors (DBRs) based on alternating layers of porous and non-porous GaN have previously been fabricated at the wafer-scale in heteroepitaxial GaN layers grown on sapphire substrates. Porosification is achieved via the electrochemical etching of highly Si-doped layers, and the etchant accesses the n+-GaN layers through nanoscale channels arising at threading dislocations that are ubiquitous in the heteroepitaxial growth process. Here, we show that the same process applies to GaN multilayer structures grown on silicon substrates. The reflectance of the resulting DBRs depends on the voltage at which the porosification process is carried out. Etching at higher voltages yields higher porosities. However, while an increase in porosity is theoretically expected to lead to peak reflectance, in practice, the highest reflectance is achieved at a moderate etching voltage because etching at higher voltages leads to pore formation in the nominally non-porous layers, pore coarsening in the porous layers, and in the worst cases layer collapse. We also find that at the high threading dislocation densities present in these samples, not all dislocations participate in the etching process at low and moderate etching voltages. However, the number of dislocations involved in the process increases with etching voltage.
Ripplocation and kink boundaries in graphene/copper nanolaminates: A molecular dynamics study
Authors: Xu Yunfei , Zhang Sen , Shi Jinchun , Zhu YinBo , Li Yingqi , Wu HengAn , Liu Xiaoyi
Published: July 2024

Over the past decade, four distinct differences have been summarized regarding ripplocation and kink boundaries in layered solids: spontaneous reversibility, atomic sharpness, delamination, and residual stress. However, according to molecular dynamics simulations, these four distinct differences are not completely applicable to the ripplocation and kink boundaries in graphene/copper nanolaminates. Contrary to conventional understanding, ripplocation boundaries can transform into kink boundaries without triggering the collective movement of other ripplocations. In addition, ripplocation boundaries can be irreversible with out-of-plane slip, leading to coherent twins in [110] orientation and stacking faults in [111] orientation. Moreover, delamination only occurs at kink boundaries rather than ripplocation boundaries. Wide-spreading residual stresses are absent for both ripplocation and kink boundaries due to plasticity. These findings broaden the current understanding of ripplocation and kink boundaries in layered solids.
Dislocation half-loop control for optimal V-defect density in GaN-based light emitting diodes
Authors: Quevedo Alejandro , Wu Feng , Tsai Tsung-Yin , Ewing Jacob J. , Tak Tanay , Gandrothula Srinivas , Gee Stephen , Li Xianqing , Nakamura Shuji , DenBaars Steven P. , Speck James S.
Published: July 2024

V-defects are morphological defects that typically form on threading dislocations during epitaxial growth of (0001)-oriented GaN layers. A V-defect is a hexagonal pyramid-shaped depression with six {101¯1}-oriented sidewalls. These semipolar sidewalls have a lower polarization barrier than the polarization barriers present between the polar c-plane quantum wells and quantum barriers and can laterally inject carriers directly into quantum wells in GaN-based light emitting diodes (LEDs). This is especially important, as the high polarization field in c-plane GaN is a significant factor in the high forward voltage of GaN LEDs. The optimal V-defect density for efficient lateral carrier injection in a GaN LED (∼109 cm−2) is typically an order of magnitude higher than the threading dislocation density of GaN grown on patterned sapphire substrates (∼108 cm−2). Pure-edge dislocation loops have been known to exist in GaN, and their formation into large V-defects via low-temperature growth with high Si-doping has recently been studied. Here, we develop a method for pure-edge threading dislocation half-loop formation and density control via disilane flow, growth temperature, and thickness of the half-loop generation layer. We also develop a method of forming the threading dislocation half-loops into V-defects of comparable size to those originating from substrate threading dislocations.
Equilibration of linear polyethylene melts with pre-defined molecular weight distributions employing united atom Monte Carlo simulations
Authors: Gerakinis Dimitrios-Paraskevas , Anogiannakis Stefanos D. , Theodorou Doros N.
Published: July 2024

Possessing control over the molecular size (molecular weight/chain length/degree of polymerization) distribution of a polymeric material is extremely important in applications. This is manifested de facto by the extensive contemporary scientific literature on processes for controlling this distribution experimentally. Yet, the literature on computational techniques for achieving prescribed molecular size distributions in simulations and exploring their impact on properties is much less abundant than its experimental/technical counterpart. Here, we develop—on the basis of united atom melt simulations employing connectivity-altering Monte Carlo moves—a new Metropolis selection criterion that drives the multichain system to a prescribed but otherwise arbitrary distribution of molecular sizes. The new formulation is a generalization of that originally proposed [P. V. K. Pant and D. N. Theodorou, Macromolecules 28, 7224 (1995)], but simpler and more computationally efficient. It requires knowledge solely of the target distribution, which need not be normalized. We have implemented the new formulation on long-chain linear polyethylene melts, obtaining excellent results. The target molecular size distribution can be provided in tabulated form, allowing absolute freedom as to the types of chain size profiles that can be simulated. Distributions for which equilibration has been achieved here for linear polyethylene include a truncated most probable, a truncated Schulz–Zimm, an arbitrary one defined in tabulated form, a broad truncated Gaussian, and a bimodal Gaussian. The last two are comparable to those encountered in industrial applications. The impact of the molecular size distribution on the properties of the simulated melts, such as density, chain dimensions, and mixing thermodynamics, is explored.
Thermal conductance of interfaces between titanium nitride and group IV semiconductors at high temperatures
Authors: Khan Samreen , Shi Xinping , Feser Joseph , Wilson Richard
Published: July 2024

Measuring the temperature dependence of material properties is a standard method for better understanding the microscopic origins for that property. Surprisingly, only a few experimental studies of thermal boundary conductance at high temperatures exist. This lack of high temperature data makes it difficult to evaluate competing theories for how inelastic processes contribute to thermal conductance. To address this, we report time domain thermoreflectance measurements of the thermal boundary conductance for TiN on diamond, silicon-carbide, silicon, and germanium between 120 and 1000 K. In all systems, the interface conductance increases monotonically without stagnating at higher temperatures. For TiN/SiC interfaces, G ranges from 330 to 1000 MW/m2-K, with a room temperature conductance of 750 MW/m2-K. The interface conductance for TiN/diamond ranges from 140 to 950 MW/m2-K. Notably, for all four interfacial systems, the conductance continues to increase with temperature even after all phonon modes in the vibrationally soft material are thermally excited. This observation suggests that inelastic processes are significant contributors to the thermal conductance in all four interfacial systems, regardless of whether the materials forming the interface are vibrationally similar or dissimilar. Our study fills a notable gap in the literature for how interfacial conductance evolves at high temperatures and tests burgeoning theories for the role of inelastic processes in interfacial thermal transport.