bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of an overmoded structure for megawatt Ka-band extended interaction klystron
Authors: Zu Yifan , Yuan Xuesong , Xu Xiaotao , Chen Qingyun , Cole Matthew T. , Yin Yong , Li Hailong , Wang Bin , Meng Lin , Yan Yang
Published: October 2023

For most applications in the millimeter wave band, corresponding to Ka and higher-frequency bands, relatively high atmospheric absorption necessitates the use of high-power sources. Here, a new approach for projecting an oversized beam tunnel in an overmoded structure by concentrating the axial field is demonstrated to meet the high-frequency and high-power demands of compact devices. Due to the enhanced intense beam loading capability of the interaction circuit, a six-cavity Ka-band extended interaction klystron with a four-coupling-hole disk-loaded structure is designed that can stably obtain high output power. An analysis of optimization tradeoffs from introducing high order modes for allowing the application of more powerful beams to improving high order mode field distribution for enhancing the electron-wave coupling and suppressing mode competition is reported. 3D particle-in-cell simulations show attainable output powers of 1.11 MW at 32.94 GHz with a saturated gain of 57 dB by injecting a 3.3 mm diameter electron beam with a current of 24 A.
An improved mode time coefficient for dynamic mode decomposition
Authors: Xu Lianchao , Liu Zhengxian , Li Xiaojian , Zhao Ming , Zhao Yijia
Published: October 2023

Dynamic mode decomposition (DMD) is widely used for extracting dominant structures of unsteady flow fields. However, the traditional mode time coefficient of DMD is assumed to change exponentially over the time. Consequently, it cannot deal with the unstable flow fields whose modes present nonexponential evolution regularities. Also, the inaccurate mode time coefficient might cause an unreasonable rank of decomposed modes, leading to the dominant modes to be ignored. To overcome these shortcomings, an improved mode time coefficient based on the Moore–Penrose pseudoinverse is proposed for the DMD, and a new integrated parameter based on the improved mode time coefficient is defined to rank the decomposed modes. The DMD with the improved mode time coefficient (abbreviated as DMD-TC) is expected to accurately describe the temporal evolutions of modes in complex forms for unstable systems and results in a more reasonable rank for the modes. To validate the DMD-TC, two complex analytical functions (a continuous case and an intermittent case) and two typical unstable flows (the flow around a cylinder and the dynamic stall of a pitching airfoil) are investigated. The results indicate that the DMD-TC can accurately describe temporal evolutions of modes with complex nonlinear regularities, including exponential, logarithmic, linear, gradually intermittent, transiently intermittent, and other complex regularities. Also, due to the improved mode time coefficient, the DMD-TC can provide a more reasonable rank for unstable modes. These improvements help to identify instantaneous dominant dynamic modes (even with minor initial amplitudes) of real unstable flow fields and accurately describe their temporal evolutions.
Acoustic radiation forces on spherical objects in a viscous fluid by Bessel beams
Authors: Fan Xudong
Published: October 2023

This study investigates acoustic radiation forces on spherical objects generated by Bessel beams in a viscous fluid. Radiation forces on elastic spheres and shells of different materials are examined using viscid expression with the thermoviscous correction included, and the results are then compared with numerical simulations based on the finite element method. The Stokes drag force for zero-order Bessel waves was theoretically derived, and in turn, a practical example of negative radiation forces is proposed and investigated together with the gravity, the buoyancy, and the drag force from acoustic streaming. It is found that the negative pulling force exists even including the positive forces from the other sources; however, the parameter regions for pulling forces are reduced especially for small objects. This work helps the further study of particle manipulations by acoustic Bessel beams in viscous fluids and also guides the experimental realization of acoustic tractor beams.
Characterization of transversely confined electron beam-generated plasma using two-dimensional particle-in-cell simulations
Authors: Cao Qinchuang , Chen Jian , Sun Haomin , Sun Guangyu , Liu Shigui , Tan Chang , Wang Zhibin
Published: October 2023

Electron beam-generated plasmas (EBPs) have been used to modify the surface properties. In certain applications, EBPs are transversely confined and their properties are of value to the treatment. In this paper, the characteristics of an electron beam-generated argon plasma, confined within a narrow gap, are investigated using a two-dimensional particle-in-cell simulation. The employed particle-in-cell/Monte Carlo collision model accounts for the electron and ion kinetics, as well as collisions between electrons and the background gas, including the elastic scattering, excitation, and impact ionization. Our simulations reveal a strong correlation between the plasma density and the beam density within the plasma bulk. The excitation of obliquely growing waves is observed, which is found to have a significant impact on the transport of beam electrons, thereby leading to the non-uniformities of plasma density and electron temperature. Specifically, the obliquely growing waves increase the local plasma density while reducing the electron temperature. These contrasting effects compensate for each other, and therefore, to some extent, smooth out the distributions of ion flux and energy flux. We further examine the variations of plasma parameters with respect to the beam current density, beam energy, and gas pressure. Increasing the beam current density or decreasing the beam energy results in higher plasma density and electron temperature, while increasing pressure leads to a higher plasma density but electron temperature scarcely changes. Based on the simulation results, we propose an approach to achieve independent control of the ion flux and energy flux by adjusting beam current density, beam energy, and pressure.
Tailoring optical nonlinearities of thin-film lithium niobate via encapsulating plasmonic nanoparticles
Authors: Sun Xiaoli , Sun Wenqing , Liu Yi , Ren Feng , Jia Yuechen , Chen Feng
Published: October 2023

The development of lithium-niobate-on-insulator (LNOI) technology has sparked the advancement of numerous on-chip photonic devices for generating and manipulating light. However, the optical absorption of thin-film LNOI is very weak, especially in the near-infrared field, due to their extremely thin absorption layer and intrinsic band structure characteristics. Here, we propose a comprehensive framework to tackle these obstacles by means of ion implantation of Ag ions, which facilitates the encapsulation of plasmonic silver (Ag) nanoparticles within LNOI thin films. Through the incorporation of Ag nanoparticles, we have observed a tailored profile of optical nonlinear absorptions in LNOI thin films, transitioning from reverse saturable absorption to saturable absorption as well as optical-induced absorption to photobleaching behaviors. Moreover, the plasmonic effect elicited by the embedded Ag nanoparticles amplifies the third-order nonlinear coefficient by an order of magnitude. This work opens an avenue toward the development of high-performance on-chip photonic devices harnessing third-order nonlinearities of LNOI.
Luminescence and mechanoluminescence of Ba4Si6O16:Eu2+, RE phosphors
Authors: Duval Alexis , Suffren Yan , Benabdesselam Mourad , Houizot Patrick , Rouxel Tanguy
Published: October 2023

The luminescence properties of green Ba4Si6O16:Eu2+, rare-earths (RE) (RE = Sc, Y, La and Lu except Pm) phosphors are reported. Their long-lasting phosphorescence is discussed in view of trap depths and concentrations determined from thermally stimulated luminescence experiments. A second emission band centered at 439 nm was evidenced at low temperatures, which stems from the substitution of Eu2+ in the two non-equivalent Ba2+ sites of Ba4Si6O16. The mechanoluminescence properties of Ba4Si6O16:Eu2+, RE phosphors are described, and a new mechanoluminescence mechanism is proposed, in the case where RE = Ho3+, involving a trap distribution from 0.694 to 0.924 eV. Mechanical loading (post UV irradiation) induces a decrease in depth of the trap distribution, leading to an increase of the luminescence intensity, whereas a drop of the luminescence intensity is observed upon unloading, following the faster release of the charge carriers.
Characteristics of wave pressure on an inclined plate
Authors: Qing Jingbo , Liu Jiabin , Bei Pengwei , Guo Anxin
Published: October 2023

In this study, the hydrodynamic pressure of regular waves acting on an inclined plate was experimentally investigated. Particle image velocimetry was used to acquire the velocity field in front of the inclined plate. Comparison of the results obtained by the linear wave theory revealed the effects of various factors, including the plate angle, wave steepness, and wave period, on the pressure profile. The pressure gradient along the plate above the still water level was analyzed to demonstrate the feasibility of the straight-line pressure distribution. Dynamic mode decomposition was used to explain the modal composition of the wave pressure evolution within a period. For large wave steepness, the second-order mode dominated at the bottom, resulting in a negative pressure at the wave crest. This phenomenon was reflected as two consecutive peaks in the pressure-time history, which are referred to as double humps. When the plate was inclined in the same direction as the incident wave, the wave became steeper, and the value of the dynamic pressure gradient increased near the still water level. However, this effect was not observed when the inclination of the plate was opposite to that of the incident wave.
Ab initio quantum scattering calculations and a new potential energy surface for the HCl(X1Σ+)–O2(X3Σg−) system: Collision-induced line shape parameters for O2-perturbed R(0) 0–0 line in H35Cl
Authors: Olejnik Artur , Jóźwiak Hubert , Gancewski Maciej , Quintas-Sánchez Ernesto , Dawes Richard , Wcisło Piotr
Published: October 2023

The remote sensing of abundance and properties of HCl—the main atmospheric reservoir of Cl atoms that directly participate in ozone depletion—is important for monitoring the partitioning of chlorine between “ozone-depleting” and “reservoir” species. Such remote studies require knowledge of the shapes of molecular resonances of HCl, which are perturbed by collisions with the molecules of the surrounding air. In this work, we report the first fully quantum calculations of collisional perturbations of the shape of a pure rotational line in H35Cl perturbed by an air-relevant molecule [as the first model system we choose the R(0) line in HCl perturbed by O2]. The calculations are performed on our new highly accurate HCl(X1Σ+)–O2(X3Σg−) potential energy surface. In addition to pressure broadening and shift, we also determine their speed dependencies and the complex Dicke parameter. This gives important input to the community discussion on the physical meaning of the complex Dicke parameter and its relevance for atmospheric spectra (previously, the complex Dicke parameter for such systems was mainly determined from phenomenological fits to experimental spectra and the physical meaning of its value in that context is questionable). We also calculate the temperature dependence of the line shape parameters and obtain agreement with the available experimental data. We estimate the total combined uncertainties of our calculations at 2% relative root-mean-square error in the simulated line shape at 296 K. This result constitutes an important step toward computational population of spectroscopic databases with accurate ab initio line shape parameters for molecular systems of terrestrial atmospheric importance.
External excitation enabled chirality reversal of exceptional points in an effective anti-PT-symmetric non-Hermitian system
Authors: Jian Yiran , Wang Yuqian , Guo Zhiwei , Hu Shengyu , Wu Bintao , Yang Yaping , Chen Hong
Published: October 2023

As a kind of phase singularity in physical systems, exceptional points (EPs) give rise to a plethora of counterintuitive phenomena, such as the asymmetric state transfer and unidirectional reflection. Especially, the eigenvectors of EP are self-orthogonal, and an inherent chirality can be determined because of the “missing dimension.” Beyond traditional wisdom, in this work, we proposed theoretically an effective anti-parity-time symmetry in a non-Hermitian system under the external excitation, and the chirality reversal from resonance EP to absorption EP is demonstrated experimentally. The essence of this phenomenon is that the external input is involved in the establishment of the eigenstates of the system. Moreover, the critical condition of chirality reversal between two types of EPs in the non-Hermitian system is analytically given. This external excitation-controlled EP not only paves an effective way to study the fundamental non-Hermitian physics in an open system but also holds great potential in the applied photonic devices such as the chiral antenna, polarization converter, and wireless communication.
Unraveling complex causal processes that affect sustainability requires more integration between empirical and modeling approaches
Authors: Schlüter Maja , Brelsford Christa , Ferraro Paul J. , Orach Kirill , Qiu Minghao , Smith Martin D.
Published: October 2023

Scientists seek to understand the causal processes that generate sustainability problems and determine effective solutions. Yet, causal inquiry in nature–society systems is hampered by conceptual and methodological challenges that arise from nature–society interdependencies and the complex dynamics they create. Here, we demonstrate how sustainability scientists can address these challenges and make more robust causal claims through better integration between empirical analyses and process- or agent-based modeling. To illustrate how these different epistemological traditions can be integrated, we present four studies of air pollution regulation, natural resource management, and the spread of COVID-19. The studies show how integration can improve empirical estimates of causal effects, inform future research designs and data collection, enhance understanding of the complex dynamics that underlie observed temporal patterns, and elucidate causal mechanisms and the contexts in which they operate. These advances in causal understanding can help sustainability scientists develop better theories of phenomena where social and ecological processes are dynamically intertwined and prior causal knowledge and data are limited. The improved causal understanding also enhances governance by helping scientists and practitioners choose among potential interventions, decide when and how the timing of an intervention matters, and anticipate unexpected outcomes. Methodological integration, however, requires skills and efforts of all involved to learn how members of the respective other tradition think and analyze nature–society systems.
Molecular determinants for cold adaptation in an Antarctic Na+/K+-ATPase
Authors: Galarza-Muñoz Gaddiel , Soto-Morales Sonia I. , Jiao Song , Holmgren Miguel , Rosenthal Joshua J. C.
Published: October 2023

Enzymes from ectotherms living in chronically cold environments have evolved structural innovations to overcome the effects of temperature on catalysis. Cold adaptation of soluble enzymes is driven by changes within their primary structure or the aqueous milieu. For membrane-embedded enzymes, like the Na+/K+-ATPase, the situation is different because changes to the lipid bilayer in which they operate may also be relevant. Although much attention has been focused on thermal adaptation within lipid bilayers, relatively little is known about the contribution of structural changes within membrane-bound enzymes themselves. The identification of specific mutations that confer temperature compensation is complicated by the presence of neutral mutations, which can be more numerous. In the present study, we identified specific amino acids in a Na+/K+-ATPase from an Antarctic octopus that underlie cold resistance. Our approach was to generate chimeras between an Antarctic clone and a temperate ortholog and then study their temperature sensitivities inXenopusoocytes using an electrophysiological approach. We identified 12 positions in the Antarctic Na+/K+-ATPase that, when transferred to the temperate ortholog, were sufficient to confer cold tolerance. Furthermore, although all 12 Antarctic mutations were required for the full phenotype, a single leucine in the third transmembrane segment (M3) imparted most of it. Mutations that confer cold resistance are mostly in transmembrane segments, at positions that face the lipid bilayer. We propose that the interface between a transmembrane enzyme and the lipid bilayer is a critical determinant of temperature sensitivity and, accordingly, has been a prime evolutionary target for thermal adaptation.
Forensic science: A judicial perspective
Authors: Rakoff Jed S. , Liu Goodwin
Published: October 2023

This article describes three major developments in forensic evidence and the use of such evidence in the courts. The first development is the advent of DNA profiling, a scientific technique for identifying and distinguishing among individuals to a high degree of probability. While DNA evidence has been used to prove guilt, it has also demonstrated that many individuals have been wrongly convicted on the basis of other forensic evidence that turned out to be unreliable. The second development is the US Supreme Court precedent requiring judges to carefully scrutinize the reliability of scientific evidence in determining whether it may be admitted in a jury trial. The third development is the publication of a formidable National Academy of Sciences report questioning the scientific validity of a wide range of forensic techniques. The article explains that, although one might expect these developments to have had a major impact on the decisions of trial judges whether to admit forensic science into evidence, in fact, the response of judges has been, and continues to be, decidedly mixed.
A scientist’s take on scientific evidence in the courtroom
Authors: Albright Thomas D.
Published: October 2023

Scientific evidence is frequently offered to answer questions of fact in a court of law. DNA genotyping may link a suspect to a homicide. Receptor binding assays and behavioral toxicology may testify to the teratogenic effects of bug repellant. As for any use of science to inform fateful decisions, the immediate question raised is one of credibility: Is the evidence a product of valid methods? Are results accurate and reproducible? While the rigorous criteria of modern science seem a natural model for this evaluation, there are features unique to the courtroom that make the decision process scarcely recognizable by normal standards of scientific investigation. First, much science lies beyond the ken of those who must decide; outside “experts” must be called upon to advise. Second, questions of fact demand immediate resolution; decisions must be based on the science of the day. Third, in contrast to the generative adversarial process of scientific investigation, which yields successive approximations to the truth, the truth-seeking strategy of American courts is terminally adversarial, which risks fracturing knowledge along lines of discord. Wary of threats to credibility, courts have adopted formal rules for determining whether scientific testimony is trustworthy. Here, I consider the effectiveness of these rules and explore tension between the scientists’ ideal that momentous decisions should be based upon the highest standards of evidence and the practical reality that those standards are difficult to meet. Justice lies in carefully crafted compromise that benefits from robust bonds between science and law.
Scientific guidelines for evaluating the validity of forensic feature-comparison methods
Authors: Scurich Nicholas , Faigman David L. , Albright Thomas D.
Published: October 2023

When it comes to questions of fact in a legal context—particularly questions about measurement, association, and causality—courts should employ ordinary standards of applied science. Applied sciences generally develop along a path that proceeds from a basic scientific discovery about some natural process to the formation of a theory of how the process works and what causes it to fail, to the development of an invention intended to assess, repair, or improve the process, to the specification of predictions of the instrument’s actions and, finally, empirical validation to determine that the instrument achieves the intended effect. These elements are salient and deeply embedded in the cultures of the applied sciences of medicine and engineering, both of which primarily grew from basic sciences. However, the inventions that underlie most forensic science disciplines have few roots in basic science, and they do not have sound theories to justify their predicted actions or results of empirical tests to prove that they work as advertised. Inspired by the “Bradford Hill Guidelines”—the dominant framework for causal inference in epidemiology—we set forth four guidelines that can be used to establish the validity of forensic comparison methods generally. This framework is not intended as a checklist establishing a threshold of minimum validity, as no magic formula determines when particular disciplines or hypotheses have passed a necessary threshold. We illustrate how these guidelines can be applied by considering the discipline of firearm and tool mark examination.
A deregulated m
6
A writer complex axis driven by BRD4 confers an epitranscriptomic vulnerability in combined DNA repair–targeted therapy
Authors: Lu Xiao , Peng Lichao , Ding Jiancheng , Li Yuanpei , Li Qing , Rao Mengchen , Shu Tong , He Xiaoniu , Liu Chen , Ye Jing , Liu Wen , You Han
Published: October 2023

Aberrant transcripts expression of the m
6
A methyltransferase complex (MTC) is widely found across human cancers, suggesting a dysregulated signaling cascade which integrates m
6
A epitranscriptome to drive tumorigenesis. However, the responsible transcriptional machinery directing the expression of distinct MTC subunits remains unclear. Here, we identified an unappreciated interplay between the histone acetyl-lysine reader BRD4 and the m
6
A writer complex across human cancers. BRD4 directly stimulates transcripts expression of seven MTC subunits, allowing the maintenance of the nuclear writer complex integrity. Upon BET inhibition, this BRD4-MTC signaling cascade accounts for global m
6
A reduction and the subsequent dynamic alteration of BRD4-dependent transcriptome, resulting in impaired DNA damage response that involves activation of homologous recombination (HR) repair and repression of apoptosis. We further demonstrated that the combined synergy upon BET/PARP inhibition largely relies on disrupted m
6
A modification of HR and apoptotic genes, counteracting PARP inhibitor (PARPi) resistance in patient-derived xenograft models. Our study revealed a widespread active cross-talk between BRD4-dependent epigenetic and MTC-mediated epitranscriptomic networks, which provides a unique therapeutic vulnerability that can be leveraged in combined DNA repair-targeted therapy.
Localized microbially induced inflammation influences distant healthy tissues in the human oral cavity
Authors: Kerns Kristopher A. , Bamashmous Shatha , Hendrickson Erik L. , Kotsakis Georgios A. , Leroux Brian G. , Daubert Diane D. , Roberts Frank A. , Chen Dandan , Trivedi Harsh M. , Darveau Richard P. , McLean Jeffrey S.
Published: October 2023

Variation in human immune response to the same bacterial or viral pathogen is well established in the literature. Variation in immune response to microbial challenge has also been observed within the human oral cavity. Our recent study focused on characterizing observed variations in microbially induced gingival inflammation—resulting in three distinct clinical Inflammatory Responder Types (IRTs): High-IRT, Low-IRT, and Slow-IRT. Here, we applied a high-resolution temporal multiomic analysis during microbially induced inflammation in order to characterize the effects of localized oral inflammation on distant healthy tissues in young healthy adults. Our results highlight a nonlocalized subclinical effect with alterations in proinflammatory host mediators and an ecological shift toward dysbiosis within the subgingival microbiome in an IRT-dependent manner—despite maintained oral hygiene. Our results provide mechanistic insight into how healthy tissues within humans are influenced by distant localized inflammation and may ultimately become susceptible to disease.
Dual-pocket inhibition of Navchannels by the antiepileptic drug lamotrigine
Authors: Huang Jian , Fan Xiao , Jin Xueqin , Teng Liming , Yan Nieng
Published: October 2023

Voltage-gated sodium (Nav) channels govern membrane excitability, thus setting the foundation for various physiological and neuronal processes. Navchannels serve as the primary targets for several classes of widely used and investigational drugs, including local anesthetics, antiepileptic drugs, antiarrhythmics, and analgesics. In this study, we present cryogenic electron microscopy (cryo-EM) structures of human Nav1.7 bound to two clinical drugs, riluzole (RLZ) and lamotrigine (LTG), at resolutions of 2.9 Å and 2.7 Å, respectively. A 3D EM reconstruction of ligand-free Nav1.7 was also obtained at 2.1 Å resolution. RLZ resides in the central cavity of the pore domain and is coordinated by residues from repeats III and IV. Whereas one LTG molecule also binds to the central cavity, the other is found beneath the intracellular gate, known as site BIG. Therefore, LTG, similar to lacosamide and cannabidiol, blocks Navchannels via a dual-pocket mechanism. These structures, complemented with docking and mutational analyses, also explain the structure–activity relationships of the LTG-related linear 6,6 series that have been developed for improved efficacy and subtype specificity on different Navchannels. Our findings reveal the molecular basis for these drugs’ mechanism of action and will aid the development of novel antiepileptic and pain-relieving drugs.
Toward a quantitative interfacial description of solvation for Li metal battery operation under extreme conditions
Authors: Holoubek John , Yu Kunpeng , Wu Junlin , Wang Shen , Li Mingqian , Gao Hongpeng , Hui Zeyu , Hyun Gayea , Yin Yijie , Mu Anthony U. , Kim Kangwoon , Liu Alex , Yu Sicen , Pascal Tod A. , Liu Ping , Chen Zheng
Published: October 2023

The future application of Li metal batteries (LMBs) at scale demands electrolytes that endow improved performance under fast-charging and low-temperature operating conditions. Recent works indicate that desolvation kinetics of Li
+
plays a crucial role in enabling such behavior. However, the modulation of this process has typically been achieved through inducing qualitative degrees of ion pairing into the system. In this work, we find that a more quantitative control of the ion pairing is crucial to minimizing the desolvation penalty at the electrified interface and thus the reversibility of the Li metal anode under kinetic strain. This effect is demonstrated in localized electrolytes based on strongly and weakly bound ether solvents that allow for the deconvolution of solvation chemistry and structure. Unexpectedly, we find that maximum degrees of ion pairing are suboptimal for ultralow temperature and high-rate operation and that reversibility is substantially improved via slight local dilution away from the saturation point. Further, we find that at the optimum degree of ion pairing for each system, weakly bound solvents still produce superior behavior. The impact of these structure and chemistry effects on charge transfer are then explicitly resolved via experimental and computational analyses. Lastly, we demonstrate that the locally optimized diethyl ether-based localized-high-concentration electrolytes supports kinetic strained operating conditions, including cycling down to −60 °C and 20-min fast charging in LMB full cells. This work demonstrates that explicit, quantitative optimization of the Li
+
solvation state is necessary for developing LMB electrolytes capable of low-temperature and high-rate operation.
Oxidative regulation of TDP-43 self-association by a β-to-α conformational switch
Authors: Gu Jinge , Zhou Xiaoming , Sutherland Lillian , Kato Masato , Jaczynska Klaudia , Rizo Josep , McKnight Steven L.
Published: October 2023

An evolutionarily conserved region of the TDP-43 low-complexity domain (LCD) twenty residues in length can adopt either an α-helical or β-strand conformation. When in the latter conformation, TDP-43 self-associates via the formation of a labile, cross-β structure. Self-association can be monitored via the formation of phase-separated protein droplets. Exposure of droplets to hydrogen peroxide leads to oxidation of conserved methionine residues distributed throughout the LCD. Oxidation disassembles the cross-β structure, thus eliminating both self-association and phase separation. Here, we demonstrate that this process reciprocally enables formation of α-helical structure in precisely the same region formerly functioning to facilitate β-strand-mediated self-association. We further observe that the α-helical conformation allows interaction with a lipid-like detergent and that exposure to lipids enhances the β-to-α conformational switch. We hypothesize that regulation of this oxidative switch will prove to be important to the control of localized translation within vertebrate cells. The experimental observations reported herein were heavily reliant on studies of 1,6-hexanediol, a chemical agent that selectively dissolves labile structures formed via the self-association of protein domains of low sequence complexity. This aliphatic alcohol is shown to exert its dissociative activity primarily via hydrogen-bonding interactions with carbonyl oxygen atoms of the polypeptide backbone. Such observations underscore the central importance of backbone-mediated protein:protein interactions that facilitate the self-association and phase separation of LCDs.
Science, evidence, law, and justice
Authors: Albright Thomas D. , Baltimore David , Mazza Anne-Marie , Mnookin Jennifer L. , Tatel David S.
Published: October 2023

For nearly 25 y, the Committee on Science, Technology, and Law (CSTL), of the National Academies of Sciences, Engineering, and Medicine, has brought together distinguished members of the science and law communities to stimulate discussions that would lead to a better understanding of the role of science in legal decisions and government policies and to a better understanding of the legal and regulatory frameworks that govern the conduct of science. Under the leadership of recent CSTL co-chairs David Baltimore and David Tatel, and CSTL director Anne-Marie Mazza, the committee has overseen many interdisciplinary discussions and workshops, such as the international summits on human genome editing and the science of implicit bias, and has delivered advisory consensus reports focusing on topics of broad societal importance, such as dual use research in the life sciences, voting systems, and advances in neural science research using organoids and chimeras. One of the most influential CSTL activities concerns the use of forensic evidence by law enforcement and the courts, with emphasis on the scientific validity of forensic methods and the role of forensic testimony in bringing about justice. As coeditors of this Special Feature, CSTL alumni Tom Albright and Jennifer Mnookin have recruited articles at the intersection of science and law that reveal an emerging scientific revolution of forensic practice, which we hope will engage a broad community of scientists, legal scholars, and members of the public with interest in science-based legal policy and justice reform.
What can the stories of a frog tell us about motion event description in Gulf Pidgin Arabic?
Authors: Louhichi Imed
Published: October 2023

Motion event description has received little attention in contact linguistics as compared to other branches of
linguistics. To address this gap, I provide an overview of the grammatical and lexical resources for the encoding of motion events
in Gulf Pidgin Arabic (GPA). 10 GPA speakers narrated the story of a boy, his dog, and his missing pet frog. The results revealed:
(a) the participants used a relatively large number of path verbs and a comprehensive number of spatial particles; (b) they showed
an overwhelming aversion to the description of manner in boundary-crossing and caused motion situations; and (c) they engineered
coercive constructions to deal with semantically complex situations. Taken together, the linguistic evidence suggests GPA is
developing into a verb-framed language type. This study adds a significant methodological and empirical weight to the existing
literature and has the potential to encourage intra- and inter-disciplinary comparative work on motion event description.
A heat-triggered triboelectric nanogenerator for self-powered wireless fire alarm
Authors: Lin Xiaobo , Su Kangyu , Yang Lanxin , Xing Chenyang , Peng Zhengchun , Meng Bo
Published: October 2023

Power supply is playing an increasingly important role in the rapidly developing era of the Internet of Things. Achieving a sustainable and clean power supply for electronic devices is an urgent and challenging task. In this study, we present a heat-triggered triboelectric nanogenerator (TENG) and develop a self-powered fire alarm system to achieve an early warning without an external power supply. A TENG comprises a gear system that can utilize the elastic potential energy of a spring. A wax block was used as a heat trigger. When melted at high temperatures, the TENG will be triggered to work and generate considerable electric energy. Within a single operation cycle of approximately 6 s, a 22 μF capacitor can be charged up to 3.7 V. Such electrical energy is sufficient to drive a wireless transmission module through an automatic switching circuit. Overall, this study provides a feasible approach for a self-powered wireless warning system in power-shortage areas.
Unidirectional reflectionless propagation in borophene plasmonic metamaterials
Authors: Li Xin , Li Ze-tong , Wang Ling-ling , Lin Qi
Published: October 2023

We propose a nonreciprocal borophene metamaterial consisting of a longitudinally separated array of double-layer borophene nanoribbons (BNRs) suspended in the air, exhibiting the unidirectional reflectionless properties at exceptional points (EPs) in the near-infrared communication band. Based on the coupled mode theory and the transfer matrix method, the transmission characteristics of light in the proposed structure can be effectively described. The internal loss and radioactive loss factors of the plasmonic system are successfully calculated by employing the theoretical model we proposed. Thus we conduct the analytical description of the unidirectional reflectionless phenomenon between two borophene plasmonic resonators, where the analytical results show excellent consistency with the finite-difference time-domain simulations. Different from the waveguide structure, the proposed structure has better adjustability that the regulation of EPs can be dynamically achieved by manipulating carrier density and the spatial separation between double-layer of BNRs. Our research results possess the possibility for promising application in tunable nanoelectronic devices in the communication band.
Single-crystalline LiNbO3 integrated onto Si-based substrates via Ar plasma-activated low-temperature direct bonding
Authors: Huang Rui , Tang Mingzhi , Kan Wanyu , Xu Hao , Wu Kai , Wang Zhiyong , Li Hui
Published: October 2023

Lithium niobate (LiNbO3) crystals are multifunctional materials with excellent performance and are widely used in integrated optical devices. In this study, 4-inch LiNbO3/Si and LiNbO3/SiO2/Si bonded pairs were obtained by optimizing Ar plasma activation. After pre-bonding was completed, a slicer was used to cut the LiNbO3/Si and LiNbO3/SiO2/Si pairs into 10 × 10 mm2 squares, respectively. The optimal annealing temperature was determined through multiple annealing experiments. Scanning acoustic microscopy was used to confirm the high bonding rates of the two bonding pairs. Based on hydrophilic experiments and atomic force microscopy, the changes in the hydrophilicity and roughness of the LiNbO3, Si, and SiO2 surfaces before and after activation can be compared. X-ray photoelectron spectroscopy was used to characterize the chemical structure composition of LiNbO3, Si, and SiO2 surfaces. The dense interface without defects was observed by transmission electron microscopy. In addition, we explained the bonding mechanism between LiNbO3 and Si-based materials. The reasons for the different bonding strengths of LiNbO3 with Si and SiO2 were also analyzed. Finally, the high bonding quality of LiNbO3 and Si-based materials can meet the stringent material requirements of Si-based LiNbO3 devices.
Stiffness analysis and parameter optimization of six-dimensional force sensor with the novel circular flexible spherical joint
Authors: Wang Zhijun , Zhang Xiaotao , Li Mengxiang
Published: October 2023

As robot haptic provider, six-dimensional force sensors are an indispensable component of industrial intelligence. To address the disadvantages of the existing six-dimensional force sensor, a novel circular flexible spherical joint is proposed, its stiffness model is derived by numerical analysis method and microelement, and the stiffness model of the circular flexible spherical joint is verified by finite element simulation. A parallel six-dimensional force sensor is designed based on a circular flexible spherical joint, and a mathematical model of the sensor was established. Based on the genetic algorithm, the structural optimization design of the circular flexible spherical joint was performed, and the structural parameters of the circular flexible spherical joints are obtained by analyzing isotropy. Finally, according to the optimization results, a sensor was developed and calibration experiments were carried out. The experimental results show that the maximum error of the sensor is 1.85%, which verifies the effectiveness of the mathematical model of the sensor, which has high measurement accuracy and can accurately measure the six-dimensional external force and moment applied to the sensor.
Emerging synthesis and characterization techniques for hybrid polymer nanocomposites
Authors: Sarma Shrutidhara , Rao V Ramgopal
Published: October 2023

Metallic nanoparticles and carbon nanotubes are two of the most promising nanomaterials, due to their distinctive properties occurring from spatial confinement of electron–hole pairs. The unique combination of metallic nanoparticles and carbon nanotubes (CNTs) in a polymer matrix offers unparalleled advantages, making them highly desirable in various fields. Advanced methods and techniques for synthesizing and characterizing hybrid metal-CNT-polymer nanocomposites have undergone significant progress in recent years, paving their integration into various fields, including aerospace, electronics, energy, water treatment and environmental remediation. These advances have allowed better understanding of nanocomposite properties and imparted ability to tune specific properties through size, shape, and distribution control of the nanofillers within the matrix material or by altering filler properties through functionalization. This study aims to critically judge the emerging tools, techniques and methods used in polymer nanocomposites with specific focus on metal-CNT based hybrid polymer nanocomposites, and suggest new avenues for research in the field. Furthermore, by examining the mechanisms affecting the performance of these composites, we can understand how the inclusion of fillers alters the microstructure and overall behavior of the material. Ultimately, this knowledge could lay the foundation for the development of novel nanocomposites with tailored properties and enhanced performance in a plethora of applications.
Impact of catalysis on n-butane oxidation in an RF atmospheric pressure plasma
Authors: Stewig C , Chauvet L , Keudell A von
Published: October 2023

The plasma catalytic oxidation of n-butane diluted in a helium oxygen RF plasma jet is used to study volatile organic compound removal to unravel plasma catalytic synergisms. The plasma conversion is tested for a stoichiometric n-butane oxygen mixture for varying plasma power and using a manganese oxide catalyst. It is shown that the interplay between plasma and catalyst is very complex. The catalyst enhances the power coupling, but also serves as a sink for oxygen atoms due to surface recombination. The surface processes are dominated by reactions of radicals and excited species from the plasma. The oxidation of n-butane at the catalyst surface is slightly enhanced. In total, however, n-butane oxidation without the catalyst is more efficient than with the catalyst, which constitutes an anti-synergism.
Surface oxides, carbides, and impurities on RF superconducting Nb and Nb3Sn: a comprehensive analysis
Authors: Sun Zeming , Baraissov Zhaslan , Dukes Catherine A , Dare Darrah K , Oseroff Thomas , Thompson Michael O , Muller David A , Liepe Matthias U
Published: October 2023

Surface structures on radio-frequency (RF) superconductors are crucially important in determining their interaction with the RF field. Here we investigate the surface compositions, structural profiles, and valence distributions of oxides, carbides, and impurities on niobium (Nb) and niobium–tin (Nb3Sn) in situ under different processing conditions. We establish the underlying mechanisms of vacuum baking and nitrogen processing in Nb and demonstrate that carbide formation induced during high-temperature baking, regardless of gas environment, determines subsequent oxide formation upon air exposure or low-temperature baking, leading to modifications of the electron population profile. Our findings support the combined contribution of surface oxides and second-phase formation to the outcome of ultra-high vacuum baking (oxygen processing) and nitrogen processing. Also, we observe that vapor-diffused Nb3Sn contains thick metastable oxides, while electrochemically synthesized Nb3Sn only has a thin oxide layer. Our findings reveal fundamental mechanisms of baking and processing Nb and Nb3Sn surface structures for high-performance superconducting RF and quantum applications.
Non-uniform current distribution in parallel-wound no-insulation high-temperature superconductor coil during ramping and fast discharging operations
Authors: Fu Yutong , Wang Yawei , Peng Weihang , Zhao Yue , Ma Guangtong , Jin Zhijian
Published: October 2023

A parallel-wound no-insulation (PWNI) high-temperature superconductor (HTS) coil is a kind of pancake-shaped no-insulation (NI) coil wound with parallel-stacked HTS tapes, which combines the characteristics of a NI coil and non-twisted stacked-tape cable. It shows a significant advantage in accelerating the ramping response compared with traditional NI HTS coils wound by a single tape, and is a promising alternative for large-scale high-field magnets. The stacked cable approach can lead to current redistribution between parallel tapes during ramping operations. It couples with the turn-to-turn current redistribution and leads to a much more complicated current redistribution inside the PWNI coil, the mechanism of which remains unclear so far. The aim of this work is to investigate electromagnetic behavior of a PWNI HTS coil in ramping and fast discharging process. A simulation model was developed by integrating an equivalent circuit network model and an improvedT–Amodel. A three-tape PWNI coil and its insulated counterpart were wound and tested, and this model was validated by charging and discharging tests. Results show that there is a significant non-uniform current distribution on parallel tapes in the same turn during ramping operations and the maximum azimuthal current (transport current) can be 2.26 times the minimum one in the three-tape PWNI coil in this study. Meanwhile, the radial current shows a considerable accumulation in the tape near turn-to-turn contacts and the radial current through the turn-to-turn contacts can be 4.16 times of that the flow through tape-to-tape contacts (parallel tapes) in the same turn. During the fast discharging process, a significant coupling current is generated in the PWNI coil, leading to a large opposite transport current in local areas; the amplitude of variation of this can be 4.66 times the initial operating current. The radial current shows a similar distribution but opposite direction to that during ramping, and its amplitude is two orders of magnitude higher. These results provide practical guidelines for the design of large-scale high-field HTS magnets.
HTS conductor coil by in-situ winding technology for large-scale high-field magnet
Authors: Gao S Y , Shi S J , Yang X S , Shen B Y , Hu X B , Zhu Y P , Wu B H , Zhao Y
Published: October 2023

High temperature superconducting (HTS) conductors have become important candidates to be used in large-scale high-field magnets, owing to its high critical current density as well as good mechanical properties. At present, there are various forms of HTS conductors proposed. In this work, we reported the fabrication of the REBCO HTS coil using in-situ winding technology. The six-layer coil with a diameter of 410 mm achieved a total current of 2562 A, and generated a central magnetic field of 7.8 mT at 77 K. The stress, deformation, and defect caused during conventional winding procedure could be significantly decreased using in-situ winding technology, indicating it has great potential for the large-scale high-field magnets in next-generation fusion reactors.
The primordial black holes that disappeared: connections to dark matter and MHz-GHz gravitational Waves
Authors: Gehrman Thomas C. , Shams Es Haghi Barmak , Sinha Kuver , Xu Tao
Published: October 2023

In the post-LIGO era, there has been a lot of focus on primordial black holes (PBHs) heavier than ∼ 1015g as potential dark matter (DM) candidates. We point out that the branch of the PBH family that disappeared — PBHs lighter than ∼ 109g that ostensibly Hawking evaporated away in the early Universe — also constitute an interesting frontier for DM physics. Hawking evaporation itself serves as a portal through which such PBHs can illuminate new physics, for example by emitting dark sector particles. Taking a simple DM scalar singlet model as a template, we compute the abundance and mass of PBHs that could have provided, by Hawking evaporation, the correct DM relic density. We consider two classes of such PBHs: those originating from curvature perturbations generated by inflation, and those originating from false vacuum collapse during a first-order phase transition. For PBHs of both origins we compute the gravitational wave (GW) signals emanating from their formation stage: from second-order effects in the case of curvature perturbations, and from sound waves in the case of phase transitions. The GW signals have peak frequencies in the MHz-GHz range typical of such light PBHs. We compute the strength of such GWs compatible with the observed DM relic density, and find that the GW signal morphology can in principle allow one to distinguish between the two PBH formation histories.