bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible, integrated modeling of tokamak stability, transport, equilibrium, and pedestal physics
Authors: Lyons B. C. , McClenaghan J. , Slendebroek T. , Meneghini O. , Neiser T. F. , Smith S. P. , Weisberg D. B. , Belli E. A. , Candy J. , Hanson J. M. , Lao L. L. , Logan N. C. , Saarelma S. , Sauter O. , Snyder P. B. , Staebler G. M. , Thome K. E. , Turnbull A. D.
Published: September 2023

The STEP (Stability, Transport, Equilibrium, and Pedestal) integrated-modeling tool has been developed in OMFIT to predict stable, tokamak equilibria self-consistently with core-transport and pedestal calculations. STEP couples theory-based codes to integrate a variety of physics, including magnetohydrodynamic stability, transport, equilibrium, pedestal formation, and current-drive, heating, and fueling. The input/output of each code is interfaced with a centralized ITER-Integrated Modelling & Analysis Suite data structure, allowing codes to be run in any order and enabling open-loop, feedback, and optimization workflows. This paradigm simplifies the integration of new codes, making STEP highly extensible. STEP has been verified against a published benchmark of six different integrated models. Core-pedestal calculations with STEP have been successfully validated against individual DIII-D H-mode discharges and across more than 500 discharges of the H98,y2 database, with a mean error in confinement time from experiment less than 19%. STEP has also reproduced results in less conventional DIII-D scenarios, including negative-central-shear and negative-triangularity plasmas. Predictive STEP modeling has been used to assess performance in several tokamak reactors. Simulations of a high-field, large-aspect-ratio reactor show significantly lower fusion power than predicted by a zero-dimensional study, demonstrating the limitations of scaling-law extrapolations. STEP predictions have found promising scenarios for an EXhaust and Confinement Integration Tokamak Experiment, including a high-pressure, 80%-bootstrap-fraction plasma. ITER modeling with STEP has shown that pellet fueling enhances fusion gain in both the baseline and advanced-inductive scenarios. Finally, STEP predictions for the SPARC baseline scenario are in good agreement with published results from the physics basis.
Structural properties and defect formation mechanisms in MBE-grown HgCdTe on InSb (211)B substrates
Authors: Pan Wenwu , Ma Shuo , Sun Xiao , Gu Renjie , Faraone Lorenzo , Lei Wen
Published: September 2023

This work investigates the structural properties of HgCdTe thin films grown on InSb (211)B substrates using molecular beam epitaxy (MBE). The Cd composition of thin films is accurately determined using non-destructive approaches based on x-ray diffraction (XRD) and reflectance infrared spectroscopy. The as-grown HgCdTe thin films exhibit characteristic surface defects with a size of 7–10 μm and density of ∼105 cm−2, resulting in an additional spread in XRD full width at half maximum. Cross-sectional transmission electron microscopy results indicate that these defects are caused by surface In droplet formation during the oxide removal process of InSb substrate, which subsequently results in the formation of In4Te3 inclusions and extended defects in MBE-grown HgCdTe. Our findings provide additional confirmation that suppressing thermally induced damage of the InSb substrate is necessary for fabricating high-performance infrared detectors using HgCdTe grown on InSb substrates.
Sub-terahertz photoacoustic effect enabling broadband ultrasound generation for underwater communication
Authors: Hirata Tomoya , Inami Masahiko , Monnai Yasuaki
Published: September 2023

Conventional wireless communication faces limitations in underwater environments due to the high electromagnetic wave attenuation. Ultrasound provides an alternative, enabling communication for underwater drones and intrabody communication for implantable devices. However, the limited bandwidth of resonance-based piezoelectric transducers remains a challenge. In addition, the significant acoustic impedance mismatch between water and air hinders cross-boundary communication and necessitates direct contact between the medium and the transducers. To overcome these challenges, we propose to use a sub-terahertz photoacoustic effect for the generation of broadband ultrasound in a non-contact manner. The photoacoustic effect generates acoustic signals in a medium through thermal expansion caused by optical irradiation. We demonstrate that the use of periodically modulated continuous-wave sub-terahertz waves around 0.1 THz enables broadband signal generation efficiently owing to their high attenuation in water. We characterize the frequency response of the generated acoustic signals and demonstrate a proof of concept for underwater communication.
Estimation of iron losses in Terfenol-D for variable DC-biased and AC excitation conditions
Authors: Chen Zekun , Yang Xin , Chen Yukai , Zheng Haobin
Published: September 2023

Giant magnetostrictive material (GMM) is well known for its hysteresis behaviors related to multiple influencing factors, such as bias magnetic field and excitation level. This feature greatly challenges the loss prediction of giant magnetostrictive transducers. The existing loss prediction models need further improvement to cover the sensitive magnetic properties of GMM. In this paper, the variations of the iron losses with the operation conditions are interpreted by the variations of the Jiles–Atherton model parameters, and a concise parameter identification procedure with great generalizability is proposed. The iron losses of Terfenol-D under variable excitation levels and the DC biases are further investigated. With the proposed procedure, the introduced eight additional modification parameters for the original Jiles–Atherton model are easy to obtain, and merely a few hysteresis loops of Terfenol-D are involved. An experimental setup is established for further demonstration. Comparisons between the measured and calculated results indicate the effectiveness of the proposed approach. Throughout the bias-excitation space within the frequency range under investigation, the iron losses can be precisely estimated with an acceptable error of less than 5%.
Effect of non-Planckian spectrum on shock velocities and subsonic to transonic transition in mid-Z witness plate elements
Authors: Ghosh Karabi , Mishra Gaurav
Published: September 2023

In this work, we obtain the shock velocities in mid-Z elements, namely, Al, Ti, and Cu by performing radiation hydrodynamic simulations using constant radiation drives consisting of equilibrium Planckian distribution along with high-energy Gaussian profiles. The drive temperatures have been varied from 80 to 270 eV, and the fraction of total energy density due to Gaussian distribution (α) changes from 0 to 0.4. Though the shock velocity in all the three elements rise with the strength of the drive temperature, its variation with α is quite complicated. Using simulations, we have shown that rear surface expansion is not responsible for the observed variation in shock velocity with the fraction of hard x rays at various temperatures and explained it in terms of distribution of total extinction coefficient over the spectral form of incident drive source leading to change in albedos. The percentage variations in shock velocities are found to be commensurate with those in albedos as expected for x-ray driven ablation process. Accurate scaling laws relating the drive temperatures with the shock velocities and α have also been obtained. In Al, subsonic to transonic transition temperature is found to increase with α, whereas in Ti it is found to decrease. We have explained the variation in transition temperature in terms of Mach number. As this transition temperature in Cu is anticipated to be high due to its higher atomic number and density, we did not observe any transition up to the temperature (500 eV) considered in this paper.
A comparison of different Fourier transform procedures for analysis of diffraction data from noble gas fluids
Authors: Proctor J. E. , Pruteanu C. G. , Moss B. , Kuzovnikov M. A. , Ackland G. J. , Monk C. W. , Anzellini S.
Published: September 2023

A comparison is made between the three principal methods for the analysis of neutron and x-ray diffraction data from noble gas fluids by direct Fourier transform. All three methods (standard Fourier transform, Lorch modification, and Soper–Barney modification) are used to analyze four different sets of diffraction data from noble gas fluids. The results are compared to the findings of a full-scale real-space structure determination, namely, Empirical Potential Structure Refinement. Conclusions are drawn on the relative merits of the three Fourier transform methods, what information can be reliably obtained using each method, and which method is most suitable for the analysis of different kinds of diffraction data. The mathematical validity of the Lorch method is critically analyzed.
Label-free microfluidic isolation of functional and viable lymphocytes from peripheral blood mononuclear cells
Authors: Raj Abhishek , Ramirez Katily , Young Katherine M. , Stone Nicholas , Shankles Peter , Ali Mehdia Nadeem Rajab , Compton Anthony Malik , Lam Wilbur , Alexeev Alexander , Sulchek Todd
Published: September 2023

The separation of peripheral blood mononuclear cells (PBMCs) into constituent blood cell types is a vital step to obtain immune cells for autologous cell therapies. The ability to separate PBMCs using label-free microfluidic techniques, based on differences in biomechanical properties, can have a number of benefits over other conventional techniques, including lower cost, ease of use, and avoidance of animal-derived labeling antibodies. Here, we report a microfluidic device that uses compressive diagonal ridges to separate PBMCs into highly pure samples of viable and functional lymphocytes. The technique utilizes the differences in the biophysical properties of PBMC sub-populations to direct the lymphocytes and monocytes into separate outlets. The biophysical properties of the monocytes and lymphocytes from healthy donors were first characterized using atomic force microscopy. Lymphocytes were found to be significantly stiffer than monocytes, with a mean cell stiffness of 1495 and 931 Pa, respectively. The differences in biophysical properties resulted in distinct trajectories through the microchannel terminating at different outlets, resulting in a lymphocyte sample with purity and viability both greater than 96% with no effect on the cells’ ability to produce interferon gamma, a cytokine crucial for innate and adaptive immunity.
Error-field penetration thresholds in ohmically heated ITER and SPARC plasmas
Authors: Fitzpatrick R.
Published: September 2023

The critical n = 1, n = 2, and n = 3 error-field amplitudes needed to trigger error-field penetration in ITER and SPARC, steady-state, ohmically heated plasmas are calculated using a standard asymptotic matching approach. The calculation incorporates plasma impurities, trapped particles, the bootstrap current, and neoclassical poloidal flow-damping. The energy confinement time is specified by the neo-Alcator scaling law in the low-density linear Ohmic confinement (LOC) regime and by the ITER-89P L-mode scaling law in the high-density saturated Ohmic confinement (SOC) regime. The response of the plasma in the inner region is calculated using a linearized version of the four-field model. At the normal operating electron number density, diamagnetic levels of rotation are found to be sufficient to protect ITER and SPARC ohmically heated plasmas from m=2/n=1 error-field penetration. On the other hand, SPARC, and especially ITER, ohmically heated plasmas may be vulnerable to n > 1 error-field penetration. ITER and SPARC ohmically heated plasmas are also slightly more susceptible to error-field penetration when the electron fluid at the rational surface rotates in the ion diamagnetic direction, rather than the electron diamagnetic direction. At electron number densities that are sufficiently low that the plasma lies in the LOC confinement regime, the error-field penetration threshold increases with increasing density. However, as soon as the electron number density becomes large enough that the plasma enters the SOC regime, the increase in the error-field penetration threshold with increasing density levels off.
Numerical investigation of the linear evolution of Tollmien–Schlichting waves over longitudinal riblet surface
Authors: Wu Kangling , Hong Zheng , Ye Kun , Ye Zhengyin
Published: September 2023

The effect of longitudinal riblets on the spatially developing Tollmien–Schlichting (T–S) waves within the boundary layer is numerically investigated by direct numerical simulation. The riblets, designed to reduce turbulent drag and featuring a blade-like shape with zero thickness, are the primary focus. Part of the flat plate is replaced by riblet surface, and T–S waves with varying frequencies are introduced prior to the onset of the riblets. Moreover, the influence of riblet size is further discussed, and the underlying mechanism by which riblets affect T–S waves is identified based on the analysis of disturbance energy equation. The results demonstrate that the presence of riblets significantly enhances the growth of T–S waves. The modulation of base flow by riblets results in the emergence of an inflection point in the velocity profile within the boundary layer, thereby enhancing the flow instability. The growth rate of T–S waves and the unstable region on the riblet surface are observed to be considerably amplified, and an increase in riblet's lateral spacing and height to spacing ratio intensifies this amplification. From the perspective of disturbance energy, it is shown that although riblets cause additional energy dissipation in their vicinity, their modification of the mean velocity gradient and the phase difference between streamwise and wall-normal velocity fluctuations contribute to a significant increase in the production term, which consequently accelerates the growth of T–S waves.
Metal contacts and Schottky barrier heights at boron arsenide interfaces: A first-principles study
Authors: Fu Zhiyong , Guo Hailing , Wang Xiting , Cao Ruyue , Zhong Hongxia , Liu Sheng , Robertson John , Guo Yuzheng , Zhang Zhaofu
Published: September 2023

The combined feature of high thermal conductivity and high carrier mobility makes cubic boron arsenide (c-BAs) promising for high power and high frequency applications. In BAs-based electronics, the interaction between metals and BAs is crucial, as it significantly affects the electronic properties. One particular parameter is the Schottky barrier height (SBH), which plays a critical role in determining the transmission properties. The interfacial contact effects of BAs (110), (111), and (100) surfaces with a variety of metals have been carefully explored using first-principles calculations in order to characterize their electrical characteristics. For p-type SBHs, over different terminations, there is a strong linear trend with increasing metal work function, with a relatively steeper pinning coefficient of ∼0.2. The results show that the SBHs follow a relation of ϕn(110) > ϕn(111) > ϕn(100). Clear metal induced gap states can be observed at the interfacial BAs, resulting in an enhanced Fermi level pinning effect. The Sc is excellent at generating Schottky contacts with relatively higher SBHs (∼0.9 eV). Pt has the smallest barrier height of ∼0.3 eV, making it ideal for ohmic electrodes with low contact resistance. This work provides insight into the properties at metal–BAs contact interfaces and provides a theoretical basis for the selection of suitable electrodes for high power BAs devices.
Pattern recognition of two-phase liquid–gas flow by discriminant analysis applied to accelerometric signals
Authors: Amoresano A. , Langella G. , Iodice P. , Quaremba G.
Published: September 2023

Optimizing heat transfer in the evaporator tubes is essential for obtaining optimal coefficients. Deviation from ideal nucleated boiling configurations can lead to rapid transitions to film boiling conditions, compromising the exchange coefficients. Detecting critical bubble flow conditions is invaluable in preventing thermal overloads and safeguarding operational integrity. The aim is to detect the type of bubble motion established in the ducts using non-intrusive techniques. To achieve this aim, accelerometric devices detect the vibrations induced by the passage of bubbles. The bubble's movement is also recorded contextually by a fast video camera capable of detecting images through a vertical transparent quartz duct. The accelerometric data, processed using discriminant analysis theory and then associated with the recorded images, give a good relationship, more than 95%, between the motion of the bubbles and their behavior characteristics. The latter in this work is represented on the plane of the phases.
Mass dipole contribution to the isotopic Soret effect in molecular mixtures
Authors: Gittus Oliver R. , Bresme Fernando
Published: September 2023

Temperature gradients induce mass separation in mixtures in a process called thermal diffusion and are quantified by the Soret coefficient ST. Thermal diffusion in fluid mixtures has been interpreted recently in terms of the so-called (pseudo-)isotopic Soret effect but only considering the mass and moment of inertia differences of the molecules. We demonstrate that the first moment of the molecular mass distribution, the mass dipole, contributes significantly to the isotopic Soret effect. To probe this physical effect, we investigate fluid mixtures consisting of rigid linear molecules that differ only by the first moment of their mass distributions. We demonstrate that such mixtures have non-zero Soret coefficients in contrast with ST = 0 predicted by current formulations. For the isotopic mixtures investigated in this work, the dependence of ST on the mass dipole arises mainly through the thermal diffusion coefficient DT. In turn, DT is correlated with the dependence of the molecular librational modes on the mass dipole. We examine the interplay of the mass dipole and the moment of inertia in defining the isotopic Soret effect and propose empirical equations that include the mass dipole contribution.
Identification of intrinsic defects and hydrogen passivation in InP using hybrid functional
Authors: Liu Jinhong , Song Yang , Xu Xiaodong , Li Weiqi , Yang Jianqun , Li Xingji
Published: September 2023

Indium phosphide is widely used in electronics and photovoltaic devices due to its high electro-optical conversion efficiency, high electron mobility, and good radiation resistance. Defects are the main limitation for the performance of InP devices. In this work, based on hybrid functional with finite size correction, electronic properties of intrinsic and H-related defects have been investigated in InP. We found that PIn defect is the most stable intrinsic defect with the lowest formation energy. Defect signals detected experimentally are defined by our calculated results. Experimentally observed electron traps with the energy level of EC − 0.66 eV and EC − 0.68 eV are ascribed to the transition level ɛ(−1/−2) and ɛ(−2/−3) of In vacancies. The hydrogenated vacancies in InP have been systematically reported in the present work. Formation energies of H-related defects indicate that hydrogen atoms prefer to bind to In vacancy than P vacancy. The formation energy of In vacancy decreases with the addition of H, while that of P vacancy increases. For hydrogenated In vacancies, it captures fewer electrons than bare In vacancies when the Fermi level is close to CBM. Especially for the VIn − 3H structure, it is 0 charge state in all Fermi levels so that it will not tend to capture electron or hole. Our work is helpful to explain experimental phenomena and radiation-induced damages and improve the performance of InP devices.
Rotational movement analysis based on Fourier-rectangular function transform for cylindrical plasma
Authors: Nishimura D. , Fujisawa A. , Yamasaki K. , Nagashima Y. , Moon C. , Nishizawa T. , Kobayashi T.-K. , Kobayashi T. , Shimizu A. , Tokuzawa T. , Ido T.
Published: September 2023

This article presents a method to estimate the rotational velocity of a cylindrical plasma from its two-dimensional images by an extended use of the Fourier-rectangular function transform, which was proposed to analyze the structure and dynamics of a cylindrical plasma [K. Yamasaki etal., J. Appl. Phys. 126, 043304 (2019)]. The proposed method is applied to tomography images of plasmas produced in a linear cylindrical device and succeeds in obtaining the radial distribution of rotational velocity and its fluctuations, providing an interesting finding, that is, the existence of flow modulation associated with m=1 mode fluctuations.
Phase transitions of carbon nanotube bundles under non-proportional triaxial compressions
Authors: Li Yaomin , Zhang Bin
Published: September 2023

Lateral compressions of (n, n) and (n, 0) single-walled carbon nanotube (SWCNT) bundles are simulated by density functional theory. Feasible transition pathways are verified by the body-centered tetragonal C4 (bct-C4) phase from the (4, 4) bundle and the carbon-centered orthorhombic C8 (Cco-C8) phase from (6, 6) and (8, 8) bundles. Three new phases, the sp3-hybridized phases Cco-C16 from the (4, 0) bundle and Cco-C32 from the (8, 0) bundle, the hexagonal phase Hex-C24 composed of sp2- and sp3-hybridized carbons from the (6, 0) bundle, under non-proportional triaxial loading are predicted. Measured hardness values for Cco-C16/C32 exceed 40 GPa, indicating super-hardness. Electronic band structures of Cco-C16/C32 exhibit a 3.64 eV bandgap, while Hex-C24 exhibits metallic carbon properties. Our results provide the potential phase transition pathways of SWCNT bundles under non-proportional compression.
Helicity-controlled switching of superconducting states by radiation pulse
Authors: Croitoru M. D. , Lounis B. , Buzdin A. I.
Published: September 2023

We provide a theoretical analysis of the possibility of using circularly polarized radiation to switch between two different quantum states of a superconducting nanoring subjected to the half quantum flux. Numerical modeling, performed in the framework of the time-dependent Ginzburg–Landau equation, reveals the condition for on-demand switching between current-carrying states with different helicities with 100% probability. An experimental demonstration of this effect will be unambiguous evidence of the inverse Faraday effect in superconductors and pave the way for the design of light-operated superconducting devices.
Evaluating the contact model for anisotropic non-Gaussian roughness in mixed lubrication regime
Authors: Gao Zhiqiang , Zhang Yu , Wei Xian , Peng Lixia , Fu Weiping , Wang Wen , Hu Weipeng
Published: September 2023

This research investigates the mixed lubrication of anisotropic non-Gaussian rough surfaces. An adaptive fluid Reynolds equation is proposed, which takes into account multiple factors such as pressure-flow factors, contact factors, and shear flow factors. The aim is to evaluate the lubrication performance of anisotropic non-Gaussian rough surfaces with transverse and longitudinal textures. We find that statistical parameters of asperities height distribution on non-Gaussian rough surfaces exert a crucial influence on contact lubrication performance, with kurtosis and skewness proving to be particularly significant. Moreover, directional effects of anisotropic rough surface textures on lubrication performance of non-Gaussian rough surfaces are complex and vary. This study proposes an innovative conclusion that optimizing asperities height distribution parameters can significantly refine the surface lubrication performance, subsequently improving operational efficiency and machinery lifespan. Furthermore, the fluid Reynolds equation developed in the paper offers theoretical support and experimental guidance for the in-depth investigation of the contact lubrication performance of non-Gaussian rough surfaces.
Quantifying interaction mechanism in infinite layer nickelate superconductors
Authors: Talantsev Evgeny F.
Published: September 2023

The connection between the long-range antiferromagnetic order in cuprates and the high-temperature superconductivity is a scientific problem that has yet to be solved after nearly four decades. The properties and difficulties of describing nickelate superconductors are similar to those of cuprates. Recently, Fowlie et al. [Nat. Phys. 18, 1043 (2022)] aimed to detect the antiferromagnetic order in R1−xSrxNiO2 (R = Nd, Pr, La; x ∼ 0, 0.2) films by using the muon spin rotation (μSR) technique. The research group reported the presence of short-range antiferromagnetic order in every nickelate studied. Here, our goal was to prove that this interaction is present in the nickelate films. We did this by analyzing the temperature dependent resistivity, ρ(T), data from the research group. Global ρ(T) data fits to the advanced Bloch–Grüneisen model showed that each of the R1−xSrxNiO2 compounds can be characterized by a unique power-law exponent, p (where p = 2 for the electron–electron scattering, p = 3 for the electron–magnon scattering, and p = 5 for the electron–phonon scattering), and global characteristic temperature, Tω (which has the meaning of the Debye temperature at p = 5). We found that p = 2.0 in Nd- and Pr-based compounds and p = 1.3 for La-based compounds. The latter value does not have any interpretation within established theoretical models. We also analyzed ρ(T) data for Nd1–xSrxNiO2(0.125≤x≤0.325) reported by Lee et al. [Nature 619, 288 (2023)]. Our analysis of nickelates led us to conclude that a new theoretical model is needed to describe ρ(T) in materials exhibiting a short-range antiferromagnetic order.
Development of zero-noise extrapolated projective quantum algorithm for accurate evaluation of molecular energetics in noisy quantum devices
Authors: Halder Sonaldeep , Shrikhande Chinmay , Maitra Rahul
Published: September 2023

The recently developed Projective Quantum Eigensolver (PQE) offers an elegant procedure to evaluate the ground state energies of molecular systems in quantum computers. However, the noise in available quantum hardware can result in significant errors in computed outcomes, limiting the realization of quantum advantage. Although PQE comes equipped with some degree of inherent noise resilience, any practical implementation with apposite accuracy would require additional routines to eliminate or mitigate the errors further. In this work, we propose a way to enhance the efficiency of PQE by developing an optimal framework for introducing Zero Noise Extrapolation (ZNE) in the nonlinear iterative procedure that outlines the PQE, leading to the formulation of ZNE-PQE. Moreover, we perform a detailed analysis of how various components involved in it affect the accuracy and efficiency of the reciprocated energy convergence trajectory. Additionally, we investigate the underlying mechanism that leads to the improvements observed in ZNE-PQE over conventional PQE by performing a comparative analysis of their residue norm landscape. This approach is expected to facilitate practical applications of quantum computing in fields related to molecular sciences, where it is essential to determine molecular energies accurately.
The special solutions of two-dimensional drift-flux equations for the two-phase flow
Authors: Yue Yu , Guo Lihui
Published: September 2023

This paper considers the special solutions of two-dimensional isentropic drift-flux equations for the two-phase flow. The nonlinear system is transformed into a second order linear partial differential equation by the hodograph and the polar coordinate transformations. Specific solutions (circulatory flow, radial flow, and spiral flow) are obtained for steady and irrotational systems. Moreover, the special solution of radial flow for the pseudo-steady two-phase flow system is obtained.
Numerical simulation of boiling behavior in vertical microchannels
Authors: Zhang Zheng , Zhang Guanmin , Wei Min , Zhang Yi , Tian Maocheng
Published: September 2023

High heat flux electronic devices put forward new requirements for heat dissipation, and boiling heat transfer technology is widely used because of its higher heat dissipation capacity. In this study, the volume of fluid method was employed, along with the incorporation of the Lee phase-change mass transfer model, to investigate two-phase flow and heat transfer in vertical upward rectangular microchannels. The heat flux was varied within the range of 10–40 kW/m2, while the mass flux was varied within the range of 200–600 kg/m2 s. With the increase in heat flux, bubble flow, slug flow, churn flow, and annular flow were found successively. A phase diagram was established to predict the flow pattern transition during the boiling process. When the flow pattern changes to the churn and the annular flow, the active nucleation site density increases obviously with the Boiling number (Bo). A new correlation was proposed for two-phase flow boiling heat transfer, suitable for vertical upward channels in microscale fluids. The friction factor obtained using the Darcy friction factor equation agrees well with the simulation results at a high-pressure drop. The instability in microchannels increases with the increase in heat flux, particularly in annular flow, resulting in more severe wall temperature fluctuations.
Accurate and efficient calculations of Hellmann–Feynman forces for quantum computation
Authors: Lai Juntao , Fan Yi , Fu Qiang , Li Zhenyu , Yang Jinlong
Published: September 2023

First-order derivatives of energies with respect to atomic coordinates are widely computed and used in quantum chemistry simulations. The rapidly emerging technology of quantum computing offers a new paradigm for solving relevant quantum chemistry equations. In this work, we have achieved analytical calculations of atomic forces based on the Hellmann–Feynman theorem within the framework of the variational quantum eigensolver. The accuracy of the approach is demonstrated by calculating the atomic forces of H2, LiH, H2O, and NH3 molecules, which are in excellent agreement with values obtained from full configuration interaction calculations. In particular, for systems with degenerate molecular orbitals, the analytical approach has a significant accuracy advantage over finite-difference-based methods and will not involve additional computational effort on a quantum computer. The calculated forces are further used to optimize the geometries of NH3 and CH4 molecules and to perform ab initio molecular dynamics simulations for the umbrella inversion of NH3, demonstrating the feasibility of the approach in practical quantum chemistry simulations.
Reproducibility of density functional approximations: How new functionals should be reported
Authors: Lehtola Susi , Marques Miguel A. L.
Published: September 2023

Density functional theory is the workhorse of chemistry and materials science, and novel density functional approximations are published every year. To become available in program packages, the novel density functional approximations (DFAs) need to be (re)implemented. However, according to our experience as developers of Libxc [Lehtola et al., SoftwareX 7, 1 (2018)], a constant problem in this task is verification due to the lack of reliable reference data. As we discuss in this work, this lack has led to several non-equivalent implementations of functionals such as Becke–Perdew 1986, Perdew–Wang 1991, Perdew–Burke–Ernzerhof, and Becke’s three-parameter hybrid functional with Lee–Yang–Parr correlation across various program packages, yielding different total energies. Through careful verification, we have also found many issues with incorrect functional forms in recent DFAs. The goal of this work is to ensure the reproducibility of DFAs. DFAs must be verifiable in order to prevent the reappearance of the above-mentioned errors and incompatibilities. A common framework for verification and testing is, therefore, needed. We suggest several ways in which reference energies can be produced with free and open source software, either with non-self-consistent calculations with tabulated atomic densities or via self-consistent calculations with various program packages. The employed numerical parameters—especially the quadrature grid—need to be converged to guarantee a ≲0.1 μEh precision in the total energy, which is nowadays routinely achievable in fully numerical calculations. Moreover, as such sub-μEh level agreement can only be achieved when fully equivalent implementations of the DFA are used, the source code of the reference implementation should also be made available in any publication describing a new DFA.
Anisotropic strain relaxation in epitaxially constrained
α
-(Al,Ga)2O3 thin films on a-plane Al2O3
Authors: Reis Anna , Hanke Michael , Lopes Joao Marcelo J. , Trampert Achim
Published: September 2023

Binary α-Ga2O3 and ternary α-(AlxGa1−x)2O3 thin films with x = 0.29 and 0.54 were deposited on a-plane Al2O3 substrates via plasma-assisted molecular beam epitaxy. The strain relaxation dynamics along three orthogonal crystal directions was investigated ex situ and in situ by synchrotron-based high-resolution x-ray diffraction. A pronounced in-plane anisotropy was observed as strain is preferably built up across [1¯1.0] whereas along [00.1] it is effectively relieved. The particular behavior depends on the Al content with almost immediate plastic relaxation for x = 0 and 0.29. For x = 0.54, strain relaxation is elastic within the first monolayers. A dislocation glide on the r-plane slip system has been identified as the dominating plastic relaxation mechanism as layers grow thicker.
Delta wing rocking motion suppression by deep reinforcement learning
Authors: Sun Wenchen , Wang Yankui , Pan Chong , Qi Zhongyang
Published: September 2023

The wing rock phenomenon is a self-excited roll motion occurring on the aircraft at high angles of attack (AoAs), which negatively impact safety and maneuverability. The limit cycle oscillation is a typical characteristic of this self-excited roll motion. A controller employing a model-free training approach is constructed on the basis of deep reinforcement learning (DRL) to address this severe nonlinear control problem. For an 80° swept delta wing model, the analytical model describing the nonlinear behavior of wing rock is presented and implemented in the simulation environment. The DRL-based controller is trained with the proximal policy optimization algorithm. A reward function is carefully designed for training to achieve excellent convergence stability. Various simulations were conducted at a series of unlearned initial conditions (roll angles, AoAs) to demonstrate the effectiveness and generalization capability of the proposed method and verify and evaluate the performance of the trained DRL controller. Finally, the scenario that undergoes disturbance is added to confirm the effectiveness and robustness of the proposed DRL-based controller. Results show that the DRL-based controller could effectively regulate the oscillation and retain the capability to suppress the un-wanted behavior with favorable generalization capability and robustness. Therefore, delta wing rocking motion suppression based on DRL has powerful intelligent control performance and provides a new idea for predicting the evolution of aerodynamics in rocking motion suppression.
Novel design strategies of three-dimensional MXene structures and their applications in metal-ion hybrid capacitors
Authors: Li Lingfang , Zeng Bin , Xiang Chuang , Liu Wen
Published: September 2023

MXene is a novel two-dimensional material that exhibits excellent competitive performance in energy storage and conversion applications due to its high electrical conductivity, good dispersibility, and abundant surface functional groups. However, the van der Waals interactions between MXene nanosheets tend to lead to stacking, which limits the number of active sites and ion dynamics. Constructing MXene materials into three-dimensional (3D) porous structures is an effective strategy to improve energy storage performance by increasing specific surface area and porosity, and decreasing ion transport distance. This review provides an overview of four novel design strategies for preparing three-dimensional MXene materials, including template-based, 3D printing, electrospinning, and gas-assisted methods, over the last 5 years (2019–2023), and explores the potential applications of 3D MXene structures in the new-type energy storage systems of metal-ion hybrid capacitors. Finally, the authors provide prospects for the future development of 3D MXene structures.
Structure of pre-miR-31 reveals an active role in Dicer–TRBP complex processing
Authors: Ma Sicong , Kotar Anita , Hall Ian , Grote Scott , Rouskin Silvi , Keane Sarah C.
Published: September 2023

As an essential posttranscriptional regulator of gene expression, microRNA (miRNA) levels must be strictly maintained. The biogenesis of many miRNAs is mediated by trans-acting protein partners through a variety of mechanisms, including remodeling of the RNA structure. miR-31 functions as an oncogene in numerous cancers, and interestingly, its biogenesis is not known to be regulated by protein-binding partners. Therefore, the intrinsic structural properties of the precursor element of miR-31 (pre-miR-31) can provide a mechanism by which its biogenesis is regulated. We determined the solution structure of pre-miR-31 to investigate the role of distinct structural elements in regulating processing by the Dicer–TRBP complex. We found that the presence or absence of mismatches within the helical stem does not strongly influence Dicer–TRBP processing of the pre-miRNAs. However, both the apical loop size and structure at the Dicing site are key elements for discrimination by the Dicer–TRBP complex. Interestingly, our NMR-derived structure reveals the presence of a triplet of base pairs that link the Dicer cleavage site and the apical loop. Mutational analysis in this region suggests that the stability of the junction region strongly influences processing by the Dicer–TRBP complex. Our results enrich our understanding of the active role that RNA structure plays in regulating miRNA biogenesis, which has direct implications for the control of gene expression.
A PAX6-regulated receptor tyrosine kinase pairs with a pseudokinase to activate immune defense upon oomycete recognition in
Caenorhabditis elegans
Authors: Drury Florence , Grover Manish , Hintze Mark , Saunders Jonathan , Fasseas Michael K. , Constantinou Charis , Barkoulas Michalis
Published: September 2023

Oomycetes were recently discovered as natural pathogens of
Caenorhabditis elegans,
and pathogen recognition alone was shown to be sufficient to activate a protective transcriptional program characterized by the expression of multiple
chitinase-like
(
chil
) genes. However, the molecular mechanisms underlying oomycete recognition in animals remain fully unknown. We performed here a forward genetic screen to uncover regulators of
chil
gene induction and found several independent loss-of-function alleles of
old-1
and
flor-1,
which encode receptor tyrosine kinases belonging to the
C. elegans
-specific KIN-16 family. We report that OLD-1 and FLOR-1 are both necessary for mounting the immune response and act in the epidermis. FLOR-1 is a pseudokinase that acts downstream of the active kinase OLD-1 and regulates OLD-1 levels at the plasma membrane. Interestingly, the
old-1
locus is adjacent to the
chil
genes in the
C. elegans
genome, thereby revealing a genetic cluster important for oomycete resistance. Furthermore, we demonstrate that
old-1
expression at the anterior side of the epidermis is regulated by the VAB-3/PAX6 transcription factor, well known for its role in visual system development in other animals. Taken together, our study reveals both conserved and species-specific factors shaping the activation and spatial characteristics of the immune response to oomycete recognition.
A CUG-initiated CATSPERθ functions in the CatSper channel assembly and serves as a checkpoint for flagellar trafficking
Authors: Huang Xiaofang , Miyata Haruhiko , Wang Huafeng , Mori Giulia , Iida-Norita Rie , Ikawa Masahito , Percudani Riccardo , Chung Jean-Ju
Published: September 2023

Calcium signaling is critical for successful fertilization. In spermatozoa, calcium influx into the sperm flagella mediated by the sperm-specific CatSper calcium channel is necessary for hyperactivated motility and male fertility. CatSper is a macromolecular complex and is repeatedly arranged in zigzag rows within four linear nanodomains along the sperm flagella. Here, we report that the
Tmem249
-encoded transmembrane (TM) domain–containing protein, CATSPERθ is essential for the CatSper channel assembly during sperm tail formation. CATSPERθ facilitates the channel assembly by serving as a scaffold for a pore-forming subunit CATSPER4. CATSPERθ is specifically localized at the interface of a CatSper dimer and can self-interact, suggesting its potential role in CatSper dimer formation. Male mice lacking CATSPERθ are infertile because the sperm lack the entire CatSper channel from sperm flagella, rendering sperm unable to hyperactivate, regardless of their normal expression in the testis. In contrast, genetic abrogation of any of the other CatSper TM subunits results in loss of CATSPERθ protein in the spermatid cells during spermatogenesis. CATSPERθ might act as a checkpoint for the properly assembled CatSper channel complex to traffic to sperm flagella. This study provides insights into the CatSper channel assembly and elucidates the physiological role of CATSPERθ in sperm motility and male fertility.
A multiple Kirkendall strategy for converting nanosized zero-valent iron to highly active Fenton-like catalyst for organics degradation
Authors: Qu Jianhua , Li Zhuoran , Bi Fuxuan , Zhang Xiubo , Zhang Bo , Li Kaige , Wang Siqi , Sun Mingze , Ma Jun , Zhang Ying
Published: September 2023

Nanosized zero-valent iron (nZVI) is a promising persulfate (PS) activator, however, its structurally dense oxide shell seriously inhibited electrons transfer for O-O bond cleavage of PS. Herein, we introduced sulfidation and phosphorus-doped biochar for breaking the pristine oxide shell with formation of FeS and FePO
4
-containing mixed shell. In this case, the faster diffusion rate of iron atoms compared to shell components triggered multiple Kirkendall effects, causing inward fluxion of vacancies with further coalescing into radial nanocracks. Exemplified by trichloroethylene (TCE) removal, such a unique “lemon-slice-like” nanocrack structure favored fast outward transfer of electrons and ferrous ions across the mixed shell to PS activation for high-efficient generation and utilization of reactive species, as evidenced by effective dechlorination (90.6%) and mineralization (85.4%) of TCE.

O
2

•
-

contributed most to TCE decomposition, moreover, the SnZVI@PBC gradually became electron-deficient and thus extracted electrons from TCE with achieving nonradical-based degradation. Compared to nZVI/PS process, the SnZVI@PBC/PS system could significantly reduce catalyst dosage (87.5%) and PS amount (68.8%) to achieve nearly complete TCE degradation, and was anti-interference, stable, and pH-universal. This study advanced mechanistic understandings of multiple Kirkendall effects-triggered nanocrack formation on nZVI with corresponding rational design of Fenton-like catalysts for organics degradation.
Unveiling order from chaos by approximate 2-localization of random matrices
Authors: Loizeau Nicolas , Morone Flaviano , Sels Dries
Published: September 2023

Quantum many-body systems are typically endowed with a tensor product structure. A structure they inherited from probability theory, where the probability of two independent events is the product of the probabilities. The tensor product structure of a Hamiltonian thus gives a natural decomposition of the system into independent smaller subsystems. It is interesting to understand whether a given Hamiltonian is compatible with some particular tensor product structure. In particular, we ask, is there a basis in which an arbitrary Hamiltonian has a 2-local form, i.e., it contains only pairwise interactions? Here we show, using analytical and numerical calculations, that a generic Hamiltonian (e.g., a large random matrix) can be approximately written as a linear combination of two-body interaction terms with high precision; that is, the Hamiltonian is 2-local in a carefully chosen basis. Moreover, we show that these Hamiltonians are not fine-tuned, meaning that the spectrum is robust against perturbations of the coupling constants. Finally, by analyzing the adjacency structure of the couplings

J

ij

, we suggest a possible mechanism for the emergence of geometric locality from quantum chaos.
A dialogic speech act approach to ridiculing references in the French presidential debate of 2022
Authors: Botaș Adina
Published: September 2023

The article proposes a dialogic approach to ridiculing in the French presidential debate of 2022, illustrating the
ridiculing act as representative of the core dynamics of political debates. The analysis enabled the configuration of a prototype
of the ridiculing act within a dialogic sequence of action and reaction, which shows that ridiculing most frequently occurs as an
immediate reaction or reactive chain to actions initiated in the free discussion sections of the dialogue. The selected dialogic
sequences are shaped by some particularities of ridiculing as a macro speech act of negative humour and the genre of the
presidential debate, such as the interplay of the different layers of meaning, as well as the fixed rules of turn-taking, the
front-staged nature of the talk and the participation framework.
Essential role of the Pax5 C-terminal domain in controlling B cell commitment and development
Authors: Gruenbacher Sarah , Jaritz Markus , Hill Louisa , Schäfer Markus , Busslinger Meinrad
Published: September 2023

The B cell regulator Pax5 consists of multiple domains whose function we analyzed in vivo by deletion in Pax5. While B lymphopoiesis was minimally affected in mice with homozygous deletion of the octapeptide or partial homeodomain, both sequences were required for optimal B cell development. Deletion of the C-terminal regulatory domain 1 (CRD1) interfered with B cell development, while elimination of CRD2 modestly affected B-lymphopoiesis. Deletion of CRD1 and CRD2 arrested B cell development at an uncommitted pro-B cell stage. Most Pax5-regulated genes required CRD1 or both CRD1 and CRD2 for their activation or repression as these domains induced or eliminated open chromatin at Pax5-activated or Pax5-repressed genes, respectively. Co-immunoprecipitation experiments demonstrated that the activating function of CRD1 is mediated through interaction with the chromatin-remodeling BAF, H3K4-methylating Set1A-COMPASS, and H4K16-acetylating NSL complexes, while its repressing function depends on recruitment of the Sin3-HDAC and MiDAC complexes. These data provide novel molecular insight into how different Pax5 domains regulate gene expression to promote B cell commitment and development.
Model-independent reconstruction of growth index via Gaussian process
Authors: Mu Yuhao , Li En-Kun , Xu Lixin
Published: September 2023

In this paper, the reconstructed growth index

γ
(
z
)

is updated by jointed combination from Pantheon+ SNe Ia samples, the observed Hubble data points H(z) at the background level, and redshift space distortion measurements of

f

σ
8

(
z
)

at the linear perturbation level via Gaussian process. The reconstructed results show that the currently available data points suggest a mild time varying growth index at low redshifts within 3σ regions. No significant deviation from ΛCDM cosmology in GR within 3σ regions was found, while the growth indices for the f(R) and the Dvali–Gabadadze–Porrati gravity are at the boundaries of 3σ regions.