bluuebunny/crossref_metadata_2025 huggingface dataset:
Sub-THz acoustic excitation of protein motion
Authors: Papež Petra , Merzel Franci , Praprotnik Matej
Published: October 2023

The application of terahertz radiation has been shown to affect both protein structure and cellular function. As the key to such structural changes lies in the dynamic response of a protein, we focus on the susceptibility of the protein’s internal dynamics to mechanical stress induced by acoustic pressure waves. We use the open-boundary molecular dynamics method, which allows us to simulate the protein exposed to acoustic waves. By analyzing the dynamic fluctuations of the protein subunits, we demonstrate that the protein is highly susceptible to acoustic waves with frequencies corresponding to those of the internal protein vibrations. This is confirmed by changes in the compactness of the protein structure. As the amplitude of the pressure wave increases, even larger deviations from average positions and larger changes in protein compactness are observed. Furthermore, performing the mode-projection analysis, we show that the breathing-like character of collective modes is enhanced at frequencies corresponding to those used to excite the protein.
Development and loss mechanism of turbine secondary flows at a low Reynolds number: A synergy analysis
Authors: Shao Ziyi , Zhang Haiyan , Wang Ruonan
Published: October 2023

To further explore the development of turbine secondary flows and associated losses at a low Reynolds number, a synergy analysis was developed and implemented. Loss is defined in terms of entropy generation in the present study. Inspired by the field synergy principle in convective heat transfer, the synergy between velocity and pressure gradient was derived from the three-dimensional mechanical energy conservation in a rotating frame. The loss of mechanical energy is not only related to the viscous dissipation but also the included angle (i.e., the synergy angle) between the velocity vector and the pressure gradient vector. A larger synergy angle (i.e., a worse synergy) is found to result in a higher loss for a fixed flow rate and pressure difference. This has been verified by both time-averaged and time-resolved numerical results. It is demonstrated that a worse synergy could be observed in high-loss regions, such as the turbine end wall, the suction-side separation and the wake. The velocity vector is not aligned with the pressure gradient vector in the vicinity of the reverse flow or the adverse pressure gradient, and the synergy angle could be employed as an indicator of these flow deteriorations. It is hoped the synergy could offer the potential method of future turbomachinery aerodynamic optimizations.
Evaporation-driven solutal-Marangoni instability in a saline solution: Theoretical and numerical studies
Authors: Hong Joung Sook , Ahn Kyung Hyun , Nam Jaewook , Kim Min Chan
Published: October 2023

The onset of solutal-capillary instability driven by evaporation through the solution–air interface is investigated theoretically and numerically in thin saline water. A scaling analysis shows that the development of the surface tension gradient is mainly driven by evaporative mass flux rather than evaporative heat flux, leading to the onset of solutal-capillary instability. The onset time of instability is theoretically analyzed through a linear stability analysis with newly derived stability equations that consider variations in the evaporative concentration, concluding that Ma·α is the most important parameter governing the onset of solutal-capillary convection, rather than Ma or α. Correspondingly, a nonlinear numerical simulation demonstrates that as evaporation proceeds, a nonvolatile salt accumulates near the evaporating interface and inhomogeneity of the concentration along the interface, which induces solutal-capillary motion, develops. The critical onset time determined from the linear stability analysis is in good agreement with the numerical simulation outcomes. The present theoretical and numerical study provides a better understanding of the evaporation-driven instability that develops in thin liquid films under the given temperature variation.
Vertical ferroelectricity in van der Waals materials: Models and devices
Authors: Zhang Yuwen , Cui Chunfeng , He Chaoyu , Ouyang Tao , Li Jin , Chen Mingxing , Tang Chao
Published: October 2023

Ferroelectricity has a wide range of applications in functional electronics, and it is extremely important for the development of the next generation of information-storage technologies. However, it is difficult to achieve in practice due to its special symmetry requirements. In this Letter, based on van der Waals stacking, a generic model is proposed for realizing ferroelectric devices in which a freely movable center layer is packaged in two fixed and symmetrically stacked layers. In this model, a ferroelectric phase transition can be realized between two equivalent and eccentric ground stacking states with opposite polarizations. By means of first-principles calculations, taking stacked hexagonal boron nitride (h-BN/h-BN/h-BN) and h-BN/graphene/h-BN as feasible models, we carefully evaluated the magnitude of ferroelectricity. The corresponding polarizations were estimated as 1.83 and 1.35 pC/m, values that are comparable to those observed in sliding ferroelectricity. Devices using this tri-layer model of vertical ferroelectricity can be constructed using arbitrary van der Waals semiconducting materials, and these will usually have low switching barriers. It is highly likely that optimized material combinations with remarkable polarization will be discovered from the huge candidate set this provides for future information-storage applications.
A small-eddy-dissipation mechanism for turbulence modeling and application to wall-bounded flows
Authors: Jin Yan
Published: October 2023

A small-eddy-dissipation (SED) mechanism is proposed in the present study for the development of turbulence models. According to the SED mechanism, a turbulence model introduces artificial dissipation to filter out small eddies so that a lower resolution mesh can be used in the simulation. In addition, the artificial dissipation should be applied outside the energy-containing range so that the large-scale motions are not affected. A small-eddy-dissipation mixing length (SED-ML) model is developed based on the SED mechanism to calculate wall-bounded flows. A local Reynolds number ys+=|det(∇u)|1/3/s is introduced in the SED-ML model to distinguish laminar flows from turbulent flows. Therefore, in addition to fully turbulent flows, the SED-ML model can also be used to calculate weakly turbulent or laminar flows. To demonstrate the performance of the SED-ML model, turbulent channel flows with the Reynolds numbers Reτ up to 4200 are simulated. The numerical results are extensively compared with the large eddy simulation (LES) results using the classical subgrid-scale models. The numerical results show that the SED-ML model predicts the statistical results with a good accuracy, while requiring a lower mesh resolution than the classical LES models. The accuracy of the calculated statistical results can be further improved by the parameter extension. The friction coefficient f for channel flows can be extended directly from the reference solution according to the relation ∂f/∂ϕ/f=−9, where ϕ is a dissipative strength coefficient. The energy and dissipation spectra confirm that the SED-ML model introduces significant dissipation at high wavenumbers. This feature is beneficial in maintaining the high accuracy of the simulation results and reducing the computational cost. The numerical study also shows that a sharp filtering of the turbulent kinetic energy in the wavenumber space is essential for the development of the turbulence model with high performance.
Soliton interactions and Mach reflection in gas bubbles–liquid mixtures
Authors: Han Xiaofeng , Jin Junru , Dong Huanhe , Fu Lei
Published: October 2023

In this study, we assume that blood is assumed to be a viscoelastic and incompressible homogeneous media in which several uniform sized oxygen bubbles are uniformly distributed. Based on this, we establish a (3 + 1)-dimensional modified Kadomtsev–Petviashvili (mKP) equation to describe the long nonlinear pressure waves in the gas bubbles–liquid mixtures. Using bell polynomials, a new bilinear form of the mKP equation is constructed, and then the one- and two-soliton solutions of the equation are obtained by the Hirota method. Via the one-soliton solutions, parametric conditions of the existence of shock wave, elevation and depression solitons, and the Mach reflection characters in the mixtures are discussed. Soliton interactions have been discussed on the basis of the two-soliton solutions. We find that the (i) parallel elastic interactions can exist between the shock and elevation solitons; (ii) oblique elastic interactions can exist between the (a) shock and depression solitons and (b) the elevation and depression solitons; and (iii) oblique inelastic interactions can exist between the two depression solitons.
Resolution-enhanced x-ray ghost imaging with polycapillary optics
Authors: Li Huiquan , Hou Wanting , Ye Zhiyuan , Yuan Tianyu , Shao Shangkun , Xiong Jun , Sun Tianxi , Sun Xuepeng
Published: October 2023

Ghost imaging (GI) enables compressive and lens-free image formation using a single-pixel detector and structured illumination, thus providing a promising and cost-effective approach to dose-reduced x-ray imaging. At this stage, a major bottleneck in almost all x-ray GI schemes is that the minimum resolution is strictly subject to the unit size of structured illumination. To overcome this widespread and inflexible resolution limitation, we introduced polycapillary optics into x-ray GI, in which polycapillary x-ray optics scaled down the input x-ray shadow pattern intactly and experimentally enabled a ∼3× resolution improvement. In general, polycapillary x-ray optics could be flexibly integrated in various x-ray GI applications with a demand of resolution larger than the diameter of the individual capillary composing of polycapillary optics, to achieve free resolution gain.
Roughness effect of an acoustic metasurface on supersonic boundary layer transition
Authors: Wang Lican , Yang Rui , Zhou Yongyi , Zhao Yilong , Zhao Yuxin
Published: October 2023

Roughness is a key property of an acoustic metasurface in determining the laminar-to-turbulent transition of a supersonic boundary layer, and the investigation of its effects requires consideration of the real microstructures inside the metasurface without any simplification. This work experimentally studies the transition behavior of the boundary layers over four different metasurfaces in a supersonic low-noise wind tunnel. Using a nanoparticle-based planar laser scattering technique and an intermittency factor analysis, it is found that the rough metasurfaces considered here tend to increase the probability of boundary layer transition more than a smooth flat plate. It is also found that the roughness of a metasurface as represented by its longitudinal scale is positively correlated with the turbulence onset probability and exhibits an interesting linear trend.
Neuromorphic synaptic applications of HfAlOx-based ferroelectric tunnel junction annealed at high temperatures to achieve high polarization
Authors: Kim Sunghun , Kim Juri , Kim Dahye , Kim Jihyung , Kim Sungjun
Published: October 2023

HfO2-based ferroelectric tunnel junctions (FTJs) are promising nonvolatile memory types for neural network applications because of their speed, low power, and excellent complementary metal-oxide semiconductor compatibility. Specifically, HfAlOx (HAO) has led to extensive research efforts owing to its outstanding ferroelectric performance. This is a result of the fact that the atomic radius of Al is smaller than that of Hf. In this study, we investigate the metal–ferroelectric–semiconductor device with an Al doping concentration of 2% that was annealed at 900 °C. A high-remnant polarization (Pr) value of 39.85 µC/cm2 and endurance were achieved by using the polarization switching positive-up-negative-down measurement method at this annealing condition. Our device shows long-term potentiation and depression properties, including high linearity and multiple conductance states for neuromorphic applications. Moreover, paired-pulse facilitation was implemented to mimic human synaptic functions. The construction of 16 states comprising four bits was achieved by employing reservoir computing with the FTJ device functioning as a physical reservoir. Finally, the results obtained from the experiment show promising outcomes for the ferroelectric memory characteristics and synaptic properties of the manufactured HAO device.
Hermite spectral method for the inelastic Boltzmann equation
Authors: Li Ruo , Lu Yixiao , Wang Yanli
Published: October 2023

We propose a Hermite spectral method for the inelastic Boltzmann equation, which makes two-dimensional periodic problem computation affordable by the hardware nowadays. This new approach involves utilizing a Hermite expansion, whereby the expansion coefficients for the variable hard sphere model are simplified into a series of summations that can be precisely derived. Additionally, a new collision model is built with a combination of the quadratic collision operator and a simplified collision operator, which helps us to balance the computational cost and the accuracy. Various numerical experiments, including spatially two-dimensional simulations, demonstrate the accuracy and efficiency of this numerical scheme.
The chlamydia care cascade of young people attending Australian general practices; a descriptive study to assess gaps in care
Authors: Jung J. , Biezen R. , Goller J. L. , Hocking J. , Chondros P. , Manski-Nankervis J.
Published: October 2023

Background Most chlamydia infections in Australia are diagnosed in general practice. The care cascade concept (testing, treatment and re-testing) can be utilised to explore the management of chlamydia infections. We explored the chlamydia care cascade among young people attending general practices in Australia. Methods We analysed de-identified electronic medical record data for 16–29-year-old individuals attending 70 Australian general practices between January 2018 and December 2020. Five outcomes: (1) chlamydia testing, (2) positivity, (3) treatment, (4) re-testing and (5) re-infection were summarised as annual counts and proportions per calendar year. Logistic regression was used to investigate the association of age, gender and clinic location with each outcome. Results During the study period, a total of 220 909 clinical episodes involving 137 358 16–29-year-olds were recorded. Of these episodes, 10.45% (n = 23 077, 95% CI 8.73–12.46) involved a chlamydia test. Of 1632 chlamydia cases, 88.79% (n = 1449, 95% CI 86.37–90.82) had appropriate antibiotics recorded as defined in Australian sexually transmitted infection management guidelines. Of 183 chlamydia cases that did not have appropriate antibiotics recorded, 46.45% (n = 85) had re-attended the clinic within 90 days of diagnosis. Among 1068 chlamydia cases that had appropriate antibiotic recorded in 2018 and 2019, 22.57% (n = 241, 95% CI 20.15–25.18) were re-tested within 6 weeks to 4 months of their diagnosis. One-third of episodes of chlamydia cases that did not have a re-test recorded (n = 281) had re-attended the clinics within 4 months of diagnosis. Conclusion Our study provides insight into chlamydia management by analysing general practice medical records, indicating substantial gaps in testing and re-testing for 16–29-year-olds. These data can also be used to explore the impact of future interventions to optimise chlamydia management.
Conservation laws and the foundations of quantum mechanics
Authors: Aharonov Yakir , Popescu Sandu , Rohrlich Daniel
Published: October 2023

In a recent paper, [Y. Aharonov, S. Popescu, D. Rohrlich,
Proc. Natl. Acad. Sci. U.S.A.
118
e1921529118 (2021)], it was argued that while the standard definition of conservation laws in quantum mechanics, which is of a statistical character, is perfectly valid, it misses essential features of nature and it can and must be revisited to address the issue of conservation/nonconservation in individual cases. Specifically, in the above paper, an experiment was presented in which it can be proven that in some individual cases, energy is not conserved, despite being conserved statistically. It was felt however that this is worrisome and that something must be wrong if there are individual instances in which conservation does not hold, even though this is not required by the standard conservation law. Here, we revisit that experiment and show that although its results are correct, there is a way to circumvent them and ensure individual case conservation in that situation. The solution is however quite unusual, challenging one of the basic assumptions of quantum mechanics, namely that any quantum state can be prepared, and it involves a time-holistic, double nonconservation effect. Our results bring light on the role of the preparation stage of the initial state of a particle and on the interplay of conservation laws and frames of reference. We also conjecture that when such a full analysis of any conservation experiment is performed, conservation is obeyed in every individual case.
Shifting decision thresholds can undermine the probative value and legal utility of forensic pattern-matching evidence
Authors: Thompson William C.
Published: October 2023

Forensic pattern analysis requires examiners to compare the patterns of items such as fingerprints or tool marks to assess whether they have a common source. This article uses signal detection theory to model examiners’ reported conclusions (e.g., identification, inconclusive, or exclusion), focusing on the connection between the examiner’s decision threshold and the probative value of the forensic evidence. It uses a Bayesian network model to explore how shifts in decision thresholds may affect rates and ratios of true and false convictions in a hypothetical legal system. It demonstrates that small shifts in decision thresholds, which may arise from contextual bias, can dramatically affect the value of forensic pattern-matching evidence and its utility in the legal system.
Enabling witnesses to actively explore faces and reinstate study-test pose during a lineup increases discriminability
Authors: Meyer Marlene , Colloff Melissa F. , Bennett Tia C. , Hirata Edward , Kohl Amelia , Stevens Laura M. , Smith Harriet M. J. , Staudigl Tobias , Flowe Heather D.
Published: October 2023

Accurate witness identification is a cornerstone of police inquiries and national security investigations. However, witnesses can make errors. We experimentally tested whether an interactive lineup, a recently introduced procedure that enables witnesses to dynamically view and explore faces from different angles, improves the rate at which witnesses identify guilty over innocent suspects compared to procedures traditionally used by law enforcement. Participants encoded 12 target faces, either from the front or in profile view, and then attempted to identify the targets from 12 lineups, half of which were target present and the other half target absent. Participants were randomly assigned to a lineup condition: simultaneous interactive, simultaneous photo, or sequential video. In the front-encoding and profile-encoding conditions, Receiver Operating Characteristics analysis indicated that discriminability was higher in interactive compared to both photo and video lineups, demonstrating the benefit of actively exploring the lineup members’ faces. Signal-detection modeling suggested interactive lineups increase discriminability because they afford the witness the opportunity to view more diagnostic features such that the nondiagnostic features play a proportionally lesser role. These findings suggest that eyewitness errors can be reduced using interactive lineups because they create retrieval conditions that enable witnesses to actively explore faces and more effectively sample features.
Stiffness transitions in new walls post-cell division differ between
Marchantia polymorpha
gemmae and
Arabidopsis
thaliana leaves
Authors: Bonfanti Alessandra , Smithers Euan Thomas , Bourdon Matthieu , Guyon Alex , Carella Philip , Carter Ross , Wightman Raymond , Schornack Sebastian , Jönsson Henrik , Robinson Sarah
Published: October 2023

Plant morphogenesis is governed by the mechanics of the cell wall—a stiff and thin polymeric box that encloses the cells. The cell wall is a highly dynamic composite material. New cell walls are added during cell division. As the cells continue to grow, the properties of cell walls are modulated to undergo significant changes in shape and size without breakage. Spatial and temporal variations in cell wall mechanical properties have been observed. However, how they relate to cell division remains an outstanding question. Here, we combine time-lapse imaging with local mechanical measurements via atomic force microscopy to systematically map the cell wall’s age and growth, with their stiffness. We make use of two systems,
Marchantia polymorpha
gemmae, and
Arabidopsis thaliana
leaves. We first characterize the growth and cell division of
M. polymorpha
gemmae. We then demonstrate that cell division in
M. polymorpha
gemmae results in the generation of a temporary stiffer and slower-growing new wall. In contrast, this transient phenomenon is absent in
A. thaliana
leaves. We provide evidence that this different temporal behavior has a direct impact on the local cell geometry via changes in the junction angle. These results are expected to pave the way for developing more realistic plant morphogenetic models and to advance the study into the impact of cell division on tissue growth.
Extreme accumulation of ammonia on electroreduced mackinawite: An abiotic ammonia storage mechanism in early ocean hydrothermal systems
Authors: Takahagi Wataru , Okada Satoshi , Matsui Yohei , Ono Shigeaki , Takai Ken , Takahashi Yoshio , Kitadai Norio
Published: October 2023

An increasing amount of evidence suggests that early ocean hydrothermal systems were sustained sources of ammonia, an essential nitrogen species for prebiotic synthesis of life’s building blocks. However, it remains a riddle how the abiotically generated ammonia was retained at the vent–ocean interface for the subsequent chemical evolution. Here, we demonstrate that, under simulated geoelectrochemical conditions in early ocean hydrothermal systems (

≤

−
0.6

V versus the standard hydrogen electrode), mackinawite gradually reduces to zero-valent iron (

Fe
0

), generating interlayer

Fe
0

sites. This reductive conversion leads to an up to 55-fold increase in the solid/liquid partition coefficient for ammonia, enabling over 90% adsorption of 1 mM ammonia in 1 M NaCl at neutral pH. A coordinative binding of ammonia on the interlayer

Fe
0

sites was computed to be the major mechanism of selective ammonia adsorption. Mackinawite is a ubiquitous sulfide precipitate in submarine hydrothermal systems. Given its reported catalytic function in amination, the extreme accumulation of ammonia on electroreduced mackinawite should have been a crucial initial step for prebiotic nitrogen assimilation, paving the way to the origin of life.
Policy instruments facilitate China’s COVID-19 work resumption
Authors: Zhao Pengjun , Liu Qiyang , Ma Tianyu , Kang Tingting , Zhou Zhengzi , Liu Zhengying , Zhang Mengzhu , Wan Jie
Published: October 2023

Governments worldwide have announced stimulus packages to remobilize the labor force after COVID-19 and therefore to cope with the COVID-19-related recession. However, it is still unclear how to facilitate large-scale work resumption. This paper aims to clarify the issue by analyzing the large-scale prefecture-level dataset of human mobility trajectory information for 320 million workers and about 500,000 policy documents in China. We model work resumption as a collective behavioral change due to configurations of capacity, motivation, and policy instruments by using qualitative comparative analysis. We find that the effectiveness of post-COVID-19 recovery stimulus varied across China depending on the fiscal and administrative capacity and the policy motivation of the prefecture. Subnational fiscal and procurement policies were more effective for the wholesale and retail sector and the hotel and catering sector, whereas the manufacturing and business services sectors required more effort regarding employment policies. Due to limited prefectural capacity and wavering policy motivation, the simultaneous adoption of fiscal, employment, and procurement policy interventions endangered post-COVID-19 work resumption. We highlight the necessity of tailored postcrisis recovery strategies based on local fiscal and administrative capacity and the sectoral structure.
A comprehensive demographic profile of the US evicted population
Authors: Graetz Nick , Gershenson Carl , Hepburn Peter , Porter Sonya R. , Sandler Danielle H. , Desmond Matthew
Published: October 2023

Millions of American renter households every year are threatened with eviction, an event associated with severe negative impacts on health and economic well-being. Yet we know little about the characteristics of individuals living in these households. Here, we link 38 million eviction court cases to US Census Bureau data to show that 7.6 million people, including 2.9 million children, faced the threat of eviction each year between 2007 and 2016. Overall, adult renters living with at least one child in their home were threatened with eviction at an annual rate of 10.4%, twice that of adults without children (5.0%). We demonstrate not only that the average evicted household includes one child, but that the most common age to experience eviction in America is during childhood. We also find that previous studies have underestimated racial disparities in eviction risk: Despite making up only 18.6% of all renters, Black Americans account for 51.1% of those affected by eviction filings and 43.4% of those evicted. Roughly one in five Black Americans living in a renter household is threatened with eviction annually, while one in ten is evicted. Black–White disparities persist across levels of income and vary by state. In providing the most comprehensive description to date of the population of US renters facing eviction, our study reveals a significant undercount of individuals impacted by eviction and motivates policies designed to stabilize housing for children and families.
Observation of fermionic time-reversal symmetry in acoustic topological metamaterials
Authors: Dong Yibao , Shi Jianbing , Wang Yuanbo , Ding Changlin , Zhao Xiaopeng
Published: October 2023

In an electronic (fermionic) system, these chiral edge states (CESs) allow inversely polarized carriers to propagate in opposite directions at the edge of the topological insulators, which is related to the time-reversal symmetry (TRS) in fermionic systems. However, in acoustic (bosonic) systems, unlike those exhibited by fermionic systems, since there is no inherent polarization, it is generally believed that the CESs protected by fermionic TRS with independent counter-propagating cannot be supported. Herein, a strategy that achieves the counter-propagating CESs in topological metamaterials with fermionic TRS is reported in a 3D acoustic system. First, we designed a Floquet evolution protocol to incorporate effective fermionic TRS. Furthermore, by utilizing metamaterials, we creatively employ two subwavelength structures, that is, a cavity structure for adjusting the phase shift and a tube structure for providing coupling, which allows the model to be miniaturized. Finally, our experiment verifies the effectiveness of our approach. Our research results enrich the knowledge of topological metamaterials in the field of topological physics and pave the way for exploring fermionic properties in bosonic systems.
Generation of terahertz waves based on nonlinear frequency conversion with double rapid adiabatic passage technique
Authors: Jia Haitao , Chen Zhen , Yu Weixian , Chen Changshui
Published: October 2023

In this paper, a nonlinear optical cascaded difference frequency generation model based on double rapid adiabatic passage technique is established, and a theoretical scheme for generating THz waves based on the above model is proposed. In this model, when the incident signal laser interacts with a pump laser, the signal laser can be completely converted into the output laser by special processing of the coupling wave equation and making reasonable assumptions. Numerical simulation results show that THz waves with a centre frequency of 260 GHz can be obtained. The maximum quantum conversion efficiency of the signal laser to THz waves is about 43.4%. Under the premise of keeping the wavelength of the pump laser unchanged, the tunable THz waves of 0.26–2.94 THz can be obtained when tuning the wavelength of the signal laser to change in the range of 1.054–1.064 μm. Compared with the scheme using stimulated Raman adiabatic passage technique, the scheme can still generate terahertz waves during the application of a pump laser to two simultaneous difference frequency generation processes, and the intensity of the pump laser can be reduced from Gigawatt level to Megawatt level. This scheme is robust to the temperature variation and provides a new method for generating terahertz wave band for high-speed wireless transmission.
Thermal rectification in mass-asymmetric one-dimensional anharmonic oscillator lattices with and without a ballistic spacer
Authors: Romero-Bastida M , Armando Martínez-Torres Brandon
Published: October 2023

In this work we perform a systematic analysis of various structural parameters that have influence on the thermal rectification effect, i.e. asymmetrical heat flow, and the negative differential thermal resistance —reduction of the heat flux as the applied thermal bias is increased— present in a one-dimensional, segmented mass-graded system consisting of a coupled nearest-neighbor harmonic oscillator lattice (ballistic spacer) and two diffusive leads (modeled by a substrate potential) attached to the lattice at both boundaries. At variance with previous works, we consider the size of the spacer as smaller than that of the leads. Also considered is the case where the leads are connected along the whole length of the oscillator lattice; that is, in the absence of the ballistic spacer. Upon variation of the system’s parameters it was determined that the performance of the device, as quantified by the spectral properties, is largely enhanced in the absence of the ballistic spacer for the small system-size limit herein considered.
A coal and gangue detection method for low light and dusty environments
Authors: Gao Jihong , Li Bo , Wang Xuewen , Zhang Jie , Wang Luyao
Published: October 2023

In practical underground production environments, low light intensity and the presence of dust can disrupt the recognition of coal and gangue. To advance the separation of coal and gangue in underground settings, this paper introduces a coal–gangue recognition approach (DG Module (DGM) + YOLOX-PSB) tailored for conditions of low light intensity and dust. To address the impact of dusty conditions, a preprocessing module (DGM) is proposed. This module employs a dark channel prior dehazing algorithm to mitigate the impact of fog on coal–gangue images. Subsequent steps include white balancing, bilateral filtering, and gamma correction to alleviate noise and distortion issues arising from the dehazing algorithm. To counteract potential drawbacks of the DGM and enhance target recognition accuracy, a polarized self-attention mechanism is integrated during the feature extraction stage to prioritize edge information of coal–gangue targets. By combining the attributes of the weighted bidirectional feature pyramid network, multiple layers of coal–gangue features are efficiently fused to achieve precise identification of coal–gangue targets. Experimental results using a custom dataset demonstrate that the enhanced algorithm outperforms YOLOv3, YOLOv5, YOLOv7-Tiny, and YOLOX, achieving a recognition accuracy of 97.6%, a frames per second rate of 99 and a good smoke concentration robustness. The proposed DGM + YOLOX-PSB serves as a valuable reference for accurate coal and gangue identification in conditions of low light intensity and dust within underground environments.
Low temperature multi-catalytic growth and growth mechanism of carbon nanotubes on carbon fiber surfaces
Authors: Yao Zhiqiang , Xia Anqi , Wang Dongzhi , Wang Chengguo
Published: October 2023

In order to reduce the etching effect of the catalysts to carbon fibers caused by high temperature during the chemical vapor deposition (CVD) process, four multi-element catalysts, Fe–Co, Fe–Ni, Co–Ni and Fe–Co–Ni, were used to realize the low temperature growth of carbon nanotubes (CNTs) on carbon fibers at 350 °C–400 °C. The results show that the growth state of CNTs has a great relationship with the type of catalysts. The catalytic efficiency of Fe–Co catalysts is low, but the graphitization degree of CNTs is relatively high. The Fe–Co–Ni catalysts has high catalytic efficiency but low graphitization degree of CNTs. The tensile strength of carbon fiber/CNTs reinforcements prepared by Fe–Ni catalysts at 400 °C is the highest, reaching 3.99 GPa, which is 11.14% higher than that of desized fiber. The melt drop phenomenon of the catalysts was found by TEM, indicating the formation of the liquid phase catalysts during the growth of CNTs. This phenomenon can change the diffusion mode of carbon atoms in the catalyst and significantly reduce the growth activation energy of CNTs, so that CNTs can grow at lower temperatures. Based on the detailed analysis of the CVD process, a low temperature growth model of CNTs on carbon fibers was proposed.
An effective hybrid feature selection using entropy weight method for automatic sleep staging
Authors: Wang Weibo , Li Junwen , Fang Yu , Zheng Yongkang , You Fang
Published: October 2023

Objective. Sleep staging is the basis for sleep quality assessment and diagnosis of sleep-related disorders. In response to the inadequacy of traditional manual judgement of sleep stages, using machine learning techniques for automatic sleep staging has become a hot topic. To improve the performance of sleep staging, numerous studies have extracted a large number of sleep-related characteristics. However, there are redundant and irrelevant features in the high-dimensional features that reduce the classification accuracy. To address this issue, an effective hybrid feature selection method based on the entropy weight method is proposed in this paper for automatic sleep staging. Approach. Firstly, we preprocess the four modal polysomnography (PSG) signals, including electroencephalogram (EEG), electrooculogram (EOG), electrocardiogram (ECG) and electromyogram (EMG). Secondly, the time domain, frequency domain and nonlinear features are extracted from the preprocessed signals, with a total of 185 features. Then, in order to acquire characteristics of the multi-modal signals that are highly correlated with the sleep stages, the proposed hybrid feature selection method is applied to choose effective features. This method is divided into two stages. In stage I, the entropy weight method is employed to combine two filter methods to build a subset of features. This stage evaluates features based on information theory and distance metrics, which can quickly obtain a subset of features and retain the relevant features. In stage II, Sequential Forward Selection is used to evaluate the subset of features and eliminate redundant features. Further more, to achieve better performance of classification, an ensemble model based on support vector machine, K-nearest neighbor, random forest and multilayer perceptron is finally constructed for classifying sleep stages. Main results. The experiment using the Cyclic Alternating Pattern (CAP) sleep database is performed to assess the performance of the method proposed in this paper. The proposed hybrid feature selection method chooses only 30 features highly correlated to sleep stages. The accuracy, F1 score and Kappa coefficient of 6 class sleep staging reach 88.86%, 83.15% and 0.8531%, respectively. Significance. Experimental results show the effectiveness of the proposed method compared to the existing state-of-the-art studies. It greatly reduces the number of features required while achieving outstanding auto-sleep staging results.
Pretreatment strategies of precursors for efficient photocatalytic hydrogen production of graphitic phase carbon nitride
Authors: Niu Fengyan , He Qisheng , Wu Shiran , Lei Weiyan , Shen Yi
Published: October 2023

The most sustainable preparation method for nanostructured materials must be urgently determined. In particular, the influence of different precursor pretreatment strategies on the structure and photocatalytic performance of highly attractive Graphitic carbon nitride photocatalyst is necessary to determine the most effective precursor pretreatment strategy. In this paper, three different precursor pretreatment methods were used to prepare g-C3N4 materials, so namely direct mixing (CN-C), freeze-drying, hydrothermal (CN-H) with thermal condensation polymerization two-step method processed urea, melamine and NH4Cl precursor mixtures. The results showed that NH4Cl, as a template, would not destroy the integrity of the tristriazine structural units in the product, and the CN-H sample had a lamellar structure, and the specific surface area and pore volume of the sample increased, which could provide more active reaction sites for photocatalytic H2 production, had the highest and most stable H2 evolution rate, up to 118.4 μmol g−1, about 1.7 times CN-C’s. This strategy provides a new idea for the design of g-C3N4 photocatalyst.
Rapid de-stiffening of multilayer transparent structures using controlled thermoplastic softening
Authors: Charaklias Dimitrios , Qiang Dayuan , Dorey Robert , Mohagheghian Iman
Published: October 2023

Thermoplastic softening is one of the most desirable de-stiffening methods because of its reversibility, scalability, and applicability in many of current multi-layered structures without compromising structural performance. Despite the advantages, long activation times and high activation power requirements are generally considered as the main drawbacks for this method which can potentially limit its application in scenarios where fast de-stiffening is required. The aim of this study is to identify the key design requirements of heating element to minimise the de-stiffening response time using thermoplastic softening while maximising transparency. The focus of this study is on multilayer transparent structures, with low heating element content. A systematic investigation, including experimental and numerical investigation, is performed to study the effect of the fill factor and the heating element’s length scale on the response time of de-stiffening. Melting of the polymer and melting or electrical breakdown of the heating element are observed as practical limitations and are introduced as constraints to the design maps. The fill factor is found to have considerable influence on improving the response time, especially at low fill factors (i.e. below 10%). For the material combinations investigated here, the design maps show that heating elements with wire diameters up to 7 μm, at maximum transparency of 2% fill factor and up to 12 μm at 20% fill factor can achieve sub-second response times for temperature increase of 30 °C. This new understanding will accelerate the technology readiness level of active structural control technology to be used in the future multi-functional and smart structures with a wide range of application in robotics, shape morphing, active damping, and active impact protection.
Improved photo sensing behavior of the terbium doped In2S3 thin films synthesized by spray pyrolysis technique
Authors: Alkallas Fatemah H , Ben Gouider Trabelsi Amira , Shkir Mohd , Gupta Manish
Published: October 2023

In the present work, undoped In2S3 and varying concentrations of Tb (1, 2, 3, 4 & 5 wt%) doped In2S3 thin films were synthesized using the economical and nebulizer spray pyrolysis technique for studying their photosensing characteristics at room temperature. X-ray diffractometer (XRD) studies showed the diffraction pattern of the thin films exhibits a cubic- β phase of In2S3 and the highest crystallite size of 61 nm was observed for the In2S3: Tb (2wt%) thin film. The morphological & elemental analysis showed that all the synthesized thin films exhibit homogeneous non-uniform crystal morphology with the existence of S, In, Tb compounds with their distinct composition. From Ultraviolet-Visible(UV–vis) studies, all the prepared thin films exhibit maximum absorption in the UV region with a minimum bandgap of 2.85 eV for the In2S3:Tb (2wt%) thin film. Also, the Photoluminescence (PL) spectra showed that the In2S3:Tb (2wt%) thin film possesses two large intense emission peaks around ∼470 nm (Yellow) and 530 nm (green). Finally, the photo sensing studies showed that the fabricated In2S3:Tb (2wt%) thin film photodetector showed better photocurrent, Responsivity (R), Detectivity (D*), External Quantum Efficiency (EQE), Response/Recovery time values of ∼12.5 μA, 0.296 AW−1, 7.75 × 1010 Jones, 60%, 2.9/3.6 s, respectively indicating the device better suitable for commercial photodetector application.
Time-dependent magnetotransport in a hybrid graphene/single magnetic molecule structure
Authors: Javadpour Ayat , Hessami Pilehrood Saeid
Published: October 2023

Graphene is potentially attractive for spintronics due to its weak intrinsic spin–orbit effect leading to a long spin relaxation length. This study examines molecular couplings on a planar graphene sheet, where one molecule is attached to the graphene sheet connected to ferromagnetic leads. The effects of a strong magnetic field, gate voltage, and time-dependent bias voltage on spin and charge tunneling currents are investigated. It is indicated that the studied model system could be controlled by applying a gate voltage and a time-dependent bias voltage. Regarding the interaction between graphene, magnetic molecule, and magnetic field, it is observed that the mutual interaction coefficients between them have the most considerable effect on the transport current. Applying the magnetic field shows that the response time of the current is very short, and the current is not zero in the steady state. In this situation, the current passes through the system continuously.
Exploring the role of heterogeneity in quorum sensing cells: a discrete state stochastic approach
Authors: Jangid Pankaj , Chaudhury Srabanti
Published: October 2023

Quorum sensing (QS) is a bacterial communication process in which cells detect the local environment and collectively activate gene expression. The transcriptional activator (LuxR) for these genes has a specific allosteric site where the autoinducer (AHL) can bind and turn the activator on. At the single-cell level, the response to gene activation is poorly coordinated among the QS population which leads to heterogeneity in an isogenic population. The paper presents a theoretical framework that uses a discrete-state stochastic approach to address the issue of heterogeneity in the context of DNA target search processes in QS cells and takes into account the relevant physical–chemical processes. This minimal model allows us to understand the molecular mechanisms of the protein target search in the context of cell heterogeneity, and evaluate the analytical expression of the protein search times for the targets on DNA. Specifically, it is shown that the variations in AHL and LuxR binding rates, arising from the asymmetric distribution of LuxR proteins in the cell population, can cause significant variations in the target search on the DNA. It is also found that the intrinsic heterogeneity in the cell population can affect the average search time and this in turn depends on the AHL and LuxR binding rates. Proposed theoretical results have been validated by Monte Carlo simulations.
Examining spatial and temporal drivers of pollinator nutritional resources: evidence from five decades of honey bee colony productivity data
Authors: Quinlan Gabriela M , Miller David A W , Grozinger Christina M
Published: October 2023

Pollinators are an essential component of terrestrial food webs and agricultural systems but are threatened by insufficient access to floral resources. Managed honey bees, as generalist foragers that hoard nectar as honey, can act as bioindicators of floral resources available to pollinators in a given landscape through their accumulation of honey. Honey yields across the United States have decreased appreciably since the 1990s, concurrent with shifts in climate, land-use, and large-scale pesticide application. While many factors can affect honey accumulation, this suggests that anthropogenic stressors may be having large-scale impacts on the floral resources that pollinators depend on for their nutrition. We used hierarchical partitioning on five decades of state-level data to parse the most important environmental factors and likely mechanisms associated with spatial and temporal variation in honey yields across the US. Climatic conditions and soil productivity were among the most important variables for estimating honey yields, with states in warm or cool regions with productive soils having the highest honey yields per colony. These findings suggest that foundational factors constrain pollinator habitat suitability and define ecoregions of low or high honey production. The most important temporally varying factors were change in herbicide use, land use (i.e. increase in intensive agriculture and reduction in land conservation programs that support pollinators) and annual weather anomalies. This study provides insights into the interplay between broad abiotic conditions and fine temporal variation on habitat suitability for honey bees and other pollinators. Our results also provide a baseline for investigating how these factors influence floral resource availability, which is essential to developing strategies for resilient plant–pollinator communities in the face of global change.