bluuebunny/crossref_metadata_2025 huggingface dataset:
Two pandemics: the COVID-19 pandemic’s impact on future AMR collaboration in Europe
Authors: Lampi Elina , Carelli Daniel , Pierre Jon , Rönnerstrand Björn
Published: July 2023

Based on 117 responses to a web survey in 29 European countries and interviews with bureaucrats in managerial positions, this paper investigates how people working professionally with antimicrobial resistance (AMR) assess the impact of the COVID-19 pandemic on their future long-run cooperation in the struggle against AMR, both within their own country and among the European countries. We measure whether the severity level of the AMR problem, cumulative COVID-19 death rates, and the daily number of confirmed new COVID-19 cases in their own countries have affected bureaucrats’ beliefs about long-run AMR collaboration. We find that around 40% of the bureaucrats believe that the cooperation will increase domestically and at the European level, indicating that global health crises such as the COVID-19 pandemic can shape future collaboration across the European countries when it comes to the equally global but more long-run health problem, AMR. However, there are considerable differences across regions: Eastern European bureaucrats are clearly the most pessimistic about future cooperation, while the Southern European and Nordic bureaucrats are the most optimistic. Neither the severity of the AMR problem nor the number of confirmed new COVID-19 cases in their own countries has a significant impact on bureaucrats’ beliefs about future collaboration. Instead, it is the cumulative COVID-19 death rate that increases the perceived likelihood of future AMR collaboration, both domestically and among the European countries. Furthermore, our interviews highlight the longer-term impact of the pandemic on public health in the EU countries and the prospect of increased EU control to prevent future cross-border health hazards. The mixed methods approach details both the broader patterns of bureaucrats’ perceptions of the impact of the pandemic on AMR-related work as well as the more long-term institutional changes that are likely to follow in the wake of the pandemic.
Toward first-principles approaches for mechanistic study of self-trapped exciton luminescence
Authors: Sun Huai-Yang , Xiong Lin , Jiang Hong
Published: July 2023

In recent years, broadband photo-luminescence phenomena arising from self-trapped exciton (STE) in metal halides, including perovskites and various low-dimensional derivatives and variants, have attracted increasing attention for their potential diverse optoelectronic applications like lighting, display, radiation detection, and sensing. Despite great success in experimental discovery of many efficient STE emitters, the current understanding of the STE emission mechanism in metal halides is still immature, and often controversial, which calls for help urgently from predictive first-principles theoretical calculation. Although density-functional theory (DFT) based calculations are routinely used to provide electronic band structure of materials and have contributed greatly to qualitative analysis of luminescence mechanism, more in-depth and quantitative information is highly needed to provide guidelines for rational design of new luminescent materials with desirable features. However, due to the complicated nature of STE emission, involving in particular electron–phonon coupling in both ground and excited states, the usage of DFT is no longer a routine job as for ground state properties. While more sophisticated methods formulated in the framework of many-body perturbation theory like GW-Bethe–Salpeter equation are available and provide theoretically rigorous and accurate description of electronic transitions in extended systems, their application to real STE systems is still severely limited due to highly demanding computational cost. In practice, approximated DFT methods are employed, which have their own strengths and limitations. In this review, we focus on the theoretical approaches that have been heavily used in interpreting STE luminescence mechanism, with a particular emphasis on theoretical methods for exciton self-trapping structural optimization. It is hoped that this review, by summarizing the current status and limitations of theoretical research in the STE emission, will motivate more methodological development efforts in this important field, and push forward the frontiers of excited state electronic structure theory of materials in general.
Understanding the role of polymers on the nucleating behavior of water in dilute supercooled solutions
Authors: Indra Aindrila , Bhendale Mangesh , Singh Jayant K.
Published: July 2023

Understanding the nucleation behavior of water in dilute polymeric solutions is quintessential for the development of suitable artificial ice recrystallization inhibition (IRI) agents. Although poly(vinyl alcohol) (PVA) is found to be one of the most potent biomimetic IRI agents, the molecular understanding of the nucleation behavior of water in the presence of PVA is still lacking. Here, we use molecular dynamics to elucidate the role of concentration, degree of supercooling, degree of polymerization, and amphiphilicity of PVA and PVA-like polymers on the homogeneous nucleation of water in dilute polymeric solutions using the seeding method. Using classical nucleation theory (CNT), our simulations indicate an increase in the chemical potential difference between ice and melt that favors ice nucleation. However, it also predicts a significant increase in the ice–melt interfacial energy that impedes nucleation. The relative increase in the interfacial energy dominates the increase in the chemical potential difference, which results in a decrease in the nucleation rate of water with an increase in the solute concentration. This study contradicts the previous simulation study that suggested the promotion of homogeneous ice nucleation by PVA and supports the experimental observations of the heterogeneous origins of ice nucleation. Our results also suggest the non-classical origins of ice nucleation in polymeric solutions and the limitation of the CNT in predicting heterogeneous ice nucleation in polymeric solutions.
Numerical investigation of thermal conductivity of Cu/graphene/Cu interface
Authors: Li Dongbo , Yang Haiying , Li Lin , Yang Ping
Published: July 2023

The purpose of this work is to investigate the contribution of in-plane and out-of-plane phonon modes to interface thermal conductivities (ITC) of the Cu/graphene/Cu interface through nonequilibrium molecular dynamics simulations. The proportions of the ITC of the in-plane and out-of-plane phonon modes in the pristine ITC are 1.1% and 99.3%, respectively. Defect engineering can change the coupling strength between in-plane and out-of-plane phonon modes. There is a strong coupling between the in-plane and the out-of-plane phonon mode when the defect concentration is lower than 3%. Phonon coupling has been transformed into weak interaction when the defect concentration is higher than 3%. The high defect concentration can suppress the coupling between in-plane and out-of-plane phonon modes. The results of the phonon density of states show that the out-of-plane phonons are mainly concentrated at low frequencies, and the in-plane phonons are mainly concentrated at high frequencies. This work helps to understand the mechanism of heat transfer of the graphene-based interface and provides theoretical guidance for the application of graphene-based interface nanodevices.
Demonstration of the AlInAsSb cascaded multiplier avalanche photodiode
Authors: McArthur J. Andrew , Dadey Adam A. , March Stephen D. , Jones Andrew H. , Xue Xingjun , Salas R. , Campbell Joe C. , Bank Seth R.
Published: July 2023

By utilizing the low-noise benefits of staircase avalanche photodiodes (APDs) and the high-field tolerance of conventional APDs, a “cascaded multiplier” device has been grown and characterized showing significantly reduced excess noise compared to k ∼ 0 materials. Because it can withstand higher electric fields than a pure staircase APD, the gain values are not limited by the number of staircase steps in the device, and higher gains are demonstrated. In addition, the cascaded multiplier device shows reduced dark current to staircase devices of similar gain. Slight adjustments to the device design could increase the gain to even higher values—further improving the signal-to-noise ratio in the detector.
Cavitation bubble induced wall shear stress on an elastic boundary
Authors: Reese Hendrik , Ohl Siew-Wan , Ohl Claus-Dieter
Published: July 2023

A cavitation bubble imposes shear stresses onto a nearby structure during its expansion and collapse. Experimentally, we probe the tangential stresses on an elastic surface by measuring the displacement of embedded particles and the deformation of an elastic structure. Corresponding numerical simulations are done using a fluid–structure interaction Volume-of-Fluid solver in OpenFOAM, where a linear elastic solid is coupled to two viscous, immiscible, and compressible fluids. We find good agreement in terms of bubble dynamics and displacement motions. During the initial bubble expansion and its first collapse, the experiment agrees with the simulation that the strain of the elastic sheet at a distance of 1.25 Rmax from the stagnation point center is larger than at 0.51 Rmax. The maximum lateral strain occurs at a non-dimensionalized bubble stand-off distance of γ≈1.1. The highest calculated wall shear stress is 250 kPa (for position y = 0). However, the largest overall shear stress of 1.9 MPa is found within the elastic sheet at y=24 μm that corresponds to a maximum displacement of Dx=44.5μm. Thus, fracture may start from within the elastic material rather than from the surface. To further examine the fluid–structure interaction, we construct a simple axisymmetrical elastic ring and analyze its deformation. In this case, we find strong deformations not only during the bubble collapse but also during the bubble's initial expansion.
Numerical approach to theoretical aspects of wedge-induced oblique detonation wave in a hydrogen concentration gradient
Authors: Iwata Kazuya
Published: July 2023

The present study conducts numerical simulations of oblique detonation wave (ODW) induced on a wedge in the concentration gradient of a hydrogen–air mixture. As a continuation of the author's previous work on the morphology of the initiating flame in a non-uniform mixture, the concentration gradient is provided only to the ODW front to address its theoretical characteristics: the propagation velocity and structures of post-shock reactive flow associated with the Chapman–Jouguet and Zeldovich–von-Neumann–Doering theories, respectively. Applying a Gaussian distribution of the hydrogen mole fraction to the ODW front induces a curved shape that is concave or convex in fuel-rich or fuel-lean compositions, respectively. The local wave angle on a curved ODW matches the one-dimensional theory in a uniform mixture, which proves its robustness in predicting the detonation velocity in a non-uniform mixture. Furthermore, tracing streamlines with different compositions reveals that the flow path and variations in temperature and pressure are almost coincident with those predicted by one-dimensional and uniform assumptions. The slight variation among the different conditions is attributed to the effects of two-dimensional convergence/divergence that are intensified at stronger gradients. The understanding achieved in the present study will also benefit the evaluation of propagating detonation in a non-uniform mixture layer formed in propulsion devices.
Angle-resolved and time-resolved spectroscopic study on large-area silver gratings fabricated via optical interference lithography
Authors: Ijaz Mohsin , Zhang Hao , Xu Liye , Blaikie Richard J.
Published: July 2023

Plasmonic resonators, which can enhance the near-field due to plasmon excitation, have attracted extensive research interest due to their significant potential in photodetection, photocatalysis, photovoltaics, and other applications. Here, we experimentally present spectroscopic results of plasmonic resonances on large-area nanoscale silver (Ag) gratings, fabricated by optical interference lithography based on angle-resolved optical absorption spectroscopy and femtosecond transient absorption spectroscopy (TAS). Specifically, we have measured plasmon resonances as a function of azimuthal angles and detection angles under p- and s-polarization. TAS reveals the non-radiative decay of plasmon resonances by transferring energy to nearby species, including exciting plasmonic hot electrons, which can be harvested by coupled semiconductors through a metal-semiconductor Schottky barrier. Our numerical simulation provides insight into the near-field analysis and quantifies the density of plasmonic hot electrons excited in our Ag-gratings.
Low voltage thick-film electroluminescent device with evaporated ZnS:Mn and spin coated BaTiO3 dielectric layer
Authors: Kitawaki Taisei , Wani Koichi , Imai Takahito , Yamamoto Shin-ichi
Published: July 2023

In a thick-dielectric electroluminescent (TDEL) device, which is a variation of thin-film electroluminescent devices, one of the insulation layers is replaced by a thick-film dielectric layer. High brightness and reliability are the features of TDEL owing to a higher withstanding voltage of the thick-film dielectric layer. This paper presents a new type of TDEL with a bottom emission structure. The thick-film dielectric layer was manufactured by spin coating using an ink material, which is a mixture of BaTiO3 powder and a binder resin. The thicknesses of the phosphor and dielectric layers were minimized to reduce the operating voltage. A threshold voltage as low as 50 V and a maximum luminance of 1000 cd/m2 were obtained at 60 V.
Enhanced temporal variation of resistive switching memories by insertion of rough titanium oxide thin film
Authors: Song Young-Woong , Yoon Jeong Hyun , Lee Sein , Ham Wooho , Park Jeong-Min , Lee Junseo , Kwon Jang-Yeon
Published: July 2023

Artificial intelligence (AI) possesses high adaptability and potential to replace human mental labor. However, only environments with high-performance computing resources and large power supplies can handle AI processing. Current computing technology is based on digital logic devices, leading to the inevitability of endless fetching of data among processors and memories. Moreover, acceleration of AI has been mainly studied at the software level, e.g., pruning of neural networks, which is insufficient for overcoming processing environment restrictions. Meanwhile, in-memory computing by physically composed neural networks is an emerging field. Resistive switching memory (RRAM) is a promising option, which is yet to be implemented because of the stochastic nature of the switching process. In this work, the temporal reliability of tantalum oxide-based RRAM was dramatically enhanced (∼1%) by the insertion of a rough titanium oxide thin film. The enhanced devices exhibited a classification accuracy of ∼88%, showing superior performance and application potential for neuromorphic computing.
Improved prediction for failure time of multilayer ceramic capacitors (MLCCs): A physics-based machine learning approach
Authors: Yousefian Pedram , Sepehrinezhad Alireza , van Duin Adri C. T. , Randall Clive A.
Published: July 2023

Multilayer ceramic capacitors (MLCC) play a vital role in electronic systems, and their reliability is of critical importance. The ongoing advancement in MLCC manufacturing has improved capacitive volumetric density for both low and high voltage devices; however, concerns about long-term stability under higher fields and temperatures are always a concern, which impact their reliability and lifespan. Consequently, predicting the mean time to failure (MTTF) for MLCCs remains a challenge due to the limitations of existing models. In this study, we develop a physics-based machine learning approach using the eXtreme Gradient Boosting method to predict the MTTF of X7R MLCCs under various temperature and voltage conditions. We employ a transfer learning framework to improve prediction accuracy for test conditions with limited data and to provide predictions for test conditions where no experimental data exists. We compare our model with the conventional Eyring model (EM) and, more recently, the tipping point model (TPM) in terms of accuracy and performance. Our results show that the machine learning model consistently outperforms both the EM and TPM, demonstrating superior accuracy and stability across different conditions. Our model also exhibits a reliable performance for untested voltage and temperature conditions, making it a promising approach for predicting MTTF in MLCCs.
Enhanced capillary performance of hierarchical dendritic copper surface for ultrathin heat-spreading devices
Authors: Chiang Chao-Yang , Yu Jui-Cheng , Liu En-Chia , Chiu Shaw-Woei , Liao Chien-Neng
Published: July 2023

High-performance electronic systems require efficient heat dissipation devices. Vapor chambers (VCs) are practical thermal solutions for lightweight portable electronics that have limited heat dissipation space. A functional VC requires an interior wick to sustain the capillary circulation of the condensed fluid back to the heated region. The capillary wick performance can be indexed by the ratio of liquid permeability to the effective pore size of the wick structure. This study describes the capillary behavior of a thin hierarchical dendritic copper film (<100 μm thick) prepared by electrodeposition and thermal sintering. The effects of the electrodeposition current density, deposition time, and sintering temperature on the capillary performance of the dendritic copper films were investigated. The relationship between the wicking capability and dendritic morphology, tailored by the electrodeposition process, was explored. A post-deposition sintering treatment was found to be beneficial for improving the structural integrity, adhesion, and capillary performance of dendritic copper wicks. A very high capillary performance (0.81 μm) was realized on a 30-μm-thick dendritic copper wick that matches the need for ultrathin VCs used in highly compact electronic systems.
Forevacuum plasma-cathode electron source for generation of a ribbon beam over a wide pressure range
Authors: Klimov A. S. , Bakeev I. Yu. , Burachevsky Yu. A. , Dagri J. E. , Oks E. M. , Zenin A. A.
Published: July 2023

We describe the results of our investigations of the generation of a ribbon electron beam (10 × 220 mm2) by a two-stage discharge system based on a hollow-cathode glow discharge plasma. The source design enables operation in the pressure range 2 × 10−2 to 10 Pa. At a beam accelerating voltage of 8 kV, the beam current is 450 mA at a pressure of 2 × 10−2 Pa and 150 mA at a pressure of 10 Pa. To achieve a uniform current density distribution of the beam over its cross-sectional area, a special design of emission electrode was employed. This enabled us to reduce non-uniformities of the beam current density distribution to a level of 10%.
Steroidogenic factor 1 (SF-1;
Nr5a1
) regulates the formation of the ovarian reserve
Authors: Hughes Camilla H. K. , Smith Olivia E. , Meinsohn Marie-Charlotte , Brunelle Mylène , Gévry Nicolas , Murphy Bruce D.
Published: July 2023

The ovarian follicle reserve, formed pre- or perinatally, comprises all oocytes for lifetime reproduction. Depletion of this reserve results in infertility. Steroidogenic factor 1 (SF-1;
Nr5a1
) and liver receptor homolog 1 (LRH-1;
Nr5a2
) are two orphan nuclear receptors that regulate adult endocrine function, but their role in follicle formation is unknown. We developed models of conditional depletion of SF-1 or LRH-1 from prenatal ovaries. Depletion of SF-1, but not LRH-1, resulted in dramatically smaller ovaries and fewer primordial follicles. This was mediated by increased oocyte death, resulting from increased ovarian inflammation and increased Notch signaling. Major dysregulated genes were Iroquois homeobox 3 and 5 and their downstream targets involved in the establishment of the ovarian laminin matrix and oocyte-granulosa cell gap junctions. Disruptions of these pathways resulted in follicles with impaired basement membrane formation and compromised oocyte–granulosa communication networks, believed to render them more prone to atresia. This study identifies SF-1 as a key regulator of the formation of the ovarian reserve.
Nascent mitochondrial proteins initiate the localized condensation of cytosolic protein aggregates on the mitochondrial surface
Authors: Liu Qingqing , Fong Benjamin , Yoo Seungmin , Unruh Jay R. , Guo Fengli , Yu Zulin , Chen Jingjing , Si Kausik , Li Rong , Zhou Chuankai
Published: July 2023

Eukaryotes organize cellular contents into membrane-bound organelles and membrane-less condensates, for example, protein aggregates. An unsolved question is why the ubiquitously distributed proteins throughout the cytosol give rise to spatially localized protein aggregates on the organellar surface, like mitochondria. We report that the mitochondrial import receptor Tom70 is involved in the localized condensation of protein aggregates in budding yeast and human cells. This is because misfolded cytosolic proteins do not autonomously aggregate in vivo; instead, they are recruited to the condensation sites initiated by Tom70’s substrates (nascent mitochondrial proteins) on the organellar membrane using multivalent hydrophobic interactions. Knocking out Tom70 partially impairs, while overexpressing Tom70 increases the formation and association between cytosolic protein aggregates and mitochondria. In addition, ectopic targeting Tom70 and its substrates to the vacuole surface is able to redirect the localized aggregation from mitochondria to the vacuolar surface. Although other redundant mechanisms may exist, this nascent mitochondrial proteins-based initiation of protein aggregation likely explains the localized condensation of otherwise ubiquitously distributed molecules on the mitochondria. Disrupting the mitochondrial association of aggregates impairs their asymmetric retention during mitosis and reduces the mitochondrial import of misfolded proteins, suggesting a proteostasis role of the organelle-condensate interactions.
Surface-induced phase separation of reconstituted nascent integrin clusters on lipid membranes
Authors: Hsu Chiao-Peng , Aretz Jonas , Hordeichyk Arsenii , Fässler Reinhard , Bausch Andreas R.
Published: July 2023

Integrin adhesion complexes are essential membrane-associated cellular compartments for metazoan life. The formation of initial integrin adhesion complexes is a dynamic process involving focal adhesion proteins assembled at the integrin cytoplasmic tails and the inner leaflet of the plasma membrane. The weak multivalent protein interactions within the complex and with the plasma membrane suggest that liquid–liquid phase separation could play a role in the nascent adhesion assembly. Here, we report that solid-supported lipid membranes supplemented with phosphoinositides induce the phase separation of minimal integrin adhesion condensates composed of integrin
β
1 tails, kindlin, talin, paxillin, and FAK at physiological ionic strengths and protein concentrations. We show that the presence of phosphoinositides is key to enriching kindlin and talin on the lipid membrane, which is necessary to further induce the phase separation of paxillin and FAK at the membrane. Our data demonstrate that lipid membrane surfaces set the local solvent conditions for steering the membrane-localized phase separation even in a regime where no condensate formation of proteins occurs in bulk solution.
Shadows and photon rings of regular black holes and geonic horizonless compact objects
Authors: Olmo Gonzalo J , Rosa João Luís , Rubiera-Garcia Diego , Sáez-Chillón Gómez Diego
Published: July 2023

The optical appearance of a body compact enough to feature an unstable bound orbit, when surrounded by an accretion disk, is expected to be dominated by a luminous ring of radiation enclosing a central brightness depression typically known as the shadow. Despite observational limitations, the rough details of this picture have been now confirmed by the results of the Event Horizon Telescope (EHT) Collaboration on the imaging of the M87 and Milky Way supermassive central objects. However, the precise characterization of both features—ring and shadow—depends on the interaction between the background geometry and the accretion disk, thus being a fertile playground to test our theories on the nature of compact objects and the gravitational field itself in the strong-field regime. In this work we use both features in order to test a continuous family of solutions interpolating between regular black holes and horizonless compact objects, which arise within the Eddington-inspired Born–Infeld theory of gravity, a viable extension of Einstein’s general relativity (GR). To this end we consider seven distinctive classes of such configurations (five black holes and two traversable wormholes) and study their optical appearances under illumination by a geometrically and optically thin accretion disk, emitting monochromatically with three analytic intensity profiles previously suggested in the literature. We build such images and consider the sub-ring structure created by light rays crossing the disk more than once and existing on top of the main ring of radiation. We discuss in detail the modifications as compared to their GR counterparts, the Lyapunov exponents of unstable nearly-bound orbits, as well as the differences between black hole and traversable wormholes for the three intensity profiles. In addition we use the claim by the EHT Collaboration on the radius of the bright ring acting (under proper calibrations) as a proxy for the radius of the shadow itself to explore the parameter space of our solutions compatible with such a result.
Plasma behavior of a low current orificed hollow cathode using krypton propellant for electric thruster applications
Authors: Liu Wei , Hu Renjie , Wang Weizong , Li Yifei , Yan Jiaqi
Published: July 2023

As a fundamental component, hollow cathodes have been widely used in electric thruster applications. Krypton has become one of the ideal alternative propellants for hollow cathode due to its economy, thus it is vital to understand the basic physical process of the discharge of krypton-fed hollow cathode. This study sets out to establish a two-dimensional fluid model coupled with the equations for gas flow and heat transfer allowing to obtain a self-consistent description of the cathode discharge. The anomalous collision term based on the formulations of Sagdeev and Galeev is considered in this model. The model is validated by comparing the simulated and measured plasma characteristic parameters and reasonable agreement is reached. The findings show that the discharge of the krypton-fed hollow cathode is characterized by the lower plasma density, higher electron temperature, and higher spatial electric potential compared to that of the xenon-fed hollow cathode and tends to present a higher plasma density in the cathode plume region when it is operating with the diode configuration. The double layer formed at the keeper orifice is an important factor for the low electron temperature distribution, which is greatly affected by the keeper current. These findings add to our understanding of plasma behavior in the discharge of a low current krypton-fed hollow cathode and support further development of credible krypton-fed hollow cathode.
Nonreciprocal terahertz wavefront manipulation based on a magneto-optical metasurface with an orthogonal meta-atom pair
Authors: Wang Hao , Fan Fei , Tan Zhi-Yu , Zhao Dan , Cheng Jie-Rong , Chang Sheng-Jiang
Published: July 2023

Active wavefront manipulation and nonreciprocal transmission give key performances in beam steering, unidirectional isolation, and multichannel multiplexing. In this work, we propose a magneto-optical (MO) Pancharatnam–Berry (PB) metasurface, which consists of a pair of orthogonal anisotropic Si and InSb columns. This orthogonal meta-atom pair (OMP) structure leads to destructive interference in the geometric phase so that the wavefront manipulation is in the OFF state without a biased magnetic field (BMF). When the BMF is applied, the nonreciprocal transmission effect for different spin states in InSb breaks the original destructive interference, so the devices provide different geometric phase distribution for different magnetic field directions and spin states, achieving the ON state of the nonreciprocal wavefront manipulation, where cross-polarization circular dichroism is higher than 0.98 and the polarization conversion rate is over 97%. Furthermore, based on this mechanism, a beam deflector and a vortex beam generator are designed by arranging the OMP with different azimuthal angles. Compared with ordinary reciprocal wavefront manipulation, this work shows that this MO PB metasurface with OMP structure has irreplaceable functions in the isolation, selection, and conversion of the two conjugate spin beams, providing a unique path for active THz wavefront manipulation.
Plasmon resonance-enhanced superior 2D MoS2 photodetector via single-layer gold nanoparticle film with ultra-high area density
Authors: Wang Dou , Han Bin , Wang Guanghui , Liu Bo , Ma Shufang , Xu Bingshe , Li Guoqiang
Published: July 2023

Molybdenum disulfide (MoS2) has been considered as a promising candidate material for photodetectors due to its unrivaled transistor behavior and strong light absorption. However, due to the ultra-thin nature of monolayer or few-layer MoS2, it exhibits a low optical cross-section, resulting in a very weak light–matter interaction and accordingly limiting the photoelectric conversion efficiency. In this work, we report a facile method to prepare single-layer gold (Au) nanoparticles with ultra-high area density according to the annealing of thin Au films. By transferring the single-layer Au nanoparticle film onto a prefabricated MoS2 photodetector, we demonstrate a photodetector with a responsivity as high as 1120 A W−1. Moreover, it is found that the response time is not affected by the Au nanoparticle decoration. This method provides an easy but effective way to fabricate high-performance two-dimensional material-based photodetectors.
Blind extraction of acoustic signals from rolling bearing composite faults based on ISCA-IMCKD
Authors: Tang Jialu , Zhou Jun , Wu Xing , Liu Tao , Liu Xiaoqin
Published: July 2023

In production practice, the signal gathered by a sensor often includes strong ambient noise, and its composition is complex. Focusing on the problem that traditional methods are difficult to separate and extract fault frequencies from strong background noise, a novel compound fault blind extraction method based on improved sparse component analysis (ISCA) and improved maximum correlation kurtosis deconvolution (IMCKD)-named ISCA‐IMCKD- is suggested. Initially, the signal that the sensor has collected is shifted into time-frequency area signal by short-time Fourier transform (STFT). In addition, the single source domain characteristic data is screened by improved single source point detection to determine the number of sources. Second, the ISCA method is optimized by using cosine distance improved fuzzy C-means clustering, which is utilized to further process the characteristic data to calculate the mixing matrix. Moreover, the estimated source signal is initially extracted according to the membership degree of clustering results. Finally, the estimated source signal is shifted into the time area by inverse STFT transform, and the IMCKD is employed to enhance the characteristics of the projected source signals. Meanwhile, the initially estimated source signal is completely separated, and the defect frequencies of the composite faults are finally extracted by envelope analysis. Simulation experiments and measured data are employed to certify the viability of the proposed means. The defect detection of rolling bearings is finished while the time cost is significantly saved.
Soft sensor modeling of cement clinker quality: a novel timing matching technique and data decoupling approach
Authors: Zhao Yantao , Wu Ruteng , Zhang Shanshan , Qu Hong , Hao Xiaochen
Published: July 2023

Clinker free calcium oxide (f-CaO) content is an important indicator of cement quality. Considering the production characteristics (strong coupling, time-varying delay) in the cement process industry, a soft sensor model was developed by combining various methods. First, a new decoupling method is proposed to deal with the strong coupling between variables, which achieves data decoupling between process variables through the attention mechanism and the long short-term memory network. Second, a novel time-series matching technique is proposed to handle the time-varying delays, which utilizes a window selection mechanism to adaptively select the time period in which each process variable influences the target variable. Third, the critical features of the variables are extracted by a one-dimensional convolution network (1D-CNN). Last, a combination of the data decoupling method, window selection mechanism, and 1D-CNN is applied to develop a soft sensor model (ADM-WGM-CNN), which implements the measurement of f-CaO content. The experimental results demonstrate that the ADM-WGM-CNN model has better measurement performance.
InGaN/GaN superlattice underlayer for fabricating of red nanocolumn μ-LEDs with (10-11) plane InGaN/AlGaN MQWs
Authors: Yamada Jumpei , Mizuno Ai , Honda Tatsuya , Yoshida Keigo , Togashi Rie , Nomura Ichirou , Yamaguchi Tomohiro , Honda Tohru , Kishino Katsumi
Published: July 2023

In this study, the growth behavior of Indium gallium nitride (InGaN)-based nanocolumn arrays was investigated, and red emission nanocolumn micro-light emitting diodes (μ-LEDs) were fabricated. The internal structure of the InGaN/GaN superlattice (SL) layer under the multiple-quantum-well (MQW) active layers was evaluated using scanning transmission electron microscopy (STEM) analysis. It was revealed that the InGaN crystal plane at the top of the nanocolumn changed from the c-plane, (1-102) plane, to the (10-11) plane as the number of SL pairs increased. A semipolar (10-11) plane was completely formed on top of the nanocolumn by growing InGaN/GaN SLs over 15–20 pairs, where the InGaN/GaN SL layers were uniformly piled up, maintaining the (10-11) plane. Therefore, when InGaN/AlGaN MQWs were grown on the (10-11) plane InGaN/GaN SL layer, the growth of the (10-11) plane semipolar InGaN active layers was observed in the high-angle annular dark field (HAADF)-STEM image. Moreover, the acute nanocolumn top of the (10-11) plane of the InGaN/GaN SL underlayer did not contribute to the formation of the c-plane InGaN core region. Red nanocolumn μ-LEDs with an φ12 μm emission window were fabricated using the (10-11) plane MQWs to obtain the external quantum efficiency of 1.01% at 51 A cm−2. The process of nanocolumn μ-LEDs suitable for the smaller emission windows was provided, where the flat p-GaN contact layer contributed to forming a fine emission window of φ5 μm.
Impact on students’ problem-solving skills by making a magnetic safe box
Authors: Pazmino A , Mosquera J , Roblero J , Romero-Vera A , Gutiérrez E D
Published: July 2023

The physical principles of electromagnetism are hard for students to understand, even though they explain our surrounding world, including technology. Active learning methodologies play an important role in students’ learning processes of such concepts. Using project-based learning, with the appropriate project, students can be engaged in any science subject. This paper studies the impact of two striking real-life projects utilizing concepts related to different learning course objectives on students’ problem-solving skills through theoretical calculations of the projects before building the prototype.
Measuring the speed of sound with a pan flute and a smartphone: a half-melodic and totally-didactic experiment
Authors: Torcal-Milla Francisco Jose
Published: July 2023

Teaching wave-physics and related phenomena with musical instruments results in a very pleasant and didactic approach for undergraduate students. Music allows teaching concepts such as frequency, amplitude, harmonics, resonance, and so on. In addition, one may use some instruments to calculate other quantities such as the air density or the speed of sound in the air. In this work, we use a conventional bamboo-made panflute and a smartphone to obtain the speed of sound in the air. The method is simple. It consists of making the pipes sound and measuring the frequency of the fundamental harmonic. The frequency is approximately proportional to the inverse of the pipe length and this dependence allows us to obtain the speed of sound quite accurately from the slope of the curve. We compare it with the theoretical value and analyse three possible causes of discrepancy such as the end correction, the air composition, or the straightness of the tubes. The proposed experiment can be carried out completely by the students since it does not involve any danger. In addition, it could be appropriate for undergraduate students or even school students.
Effect of spatial-domain pulse width on the resolution of scattering images in ultrasound computed tomography
Authors: Zhang Qiude , Liu Quanquan , Liu Zhaohui , Ding Mingyue , Yuchi Ming
Published: July 2023

Full-aperture tomography (FAT) is the major image reconstruction method for a circular ring array (CRA)-based ultrasound computed tomography (USCT) system. The FAT technique requires transferring the reconstruction process from the temporal domain to the spatial domain, during which the imaging resolution of the USCT is degraded by the spatial-domain pulse width (SDPW) of backprojection areas. To tackle this challenge, this study investigates the characteristics of the SDPW and how it degrades the image resolution. We show that the SDPW depends on the frequency of the ultrasound and the position of the transmitting elements, receiving elements and the imaging point. To quantify the deterioration of image resolution associated with the position of the transmitting and receiving elements, a SDPW broadening factor (SDPWBF) is introduced. The results of numerical simulation show a smaller SDPWBF provides a better reflection image resolution, and the distribution of SDPWBF shows that a shorter distance between the receiving element and the transmitting element yields a smaller SDPWBF. The SDPWBF is therefore able to be an indicator of selecting the signals acquired from the transmitting and receiving elements to perform optimal image resolution. Single-scatterer phantom and in
vivo experiments demonstrate how the SDPWBF affects the USCT image spatial resolution and signal-to-noise ratio (SNR), and the results agree well with the theoretical predictions.
A reaction mechanism for oxygen plasmas
Authors: Dias Tiago C , Fromentin Chloé , Alves Luís L , Tejero-del-Caz Antonio , Silva Tiago , Guerra Vasco
Published: July 2023

This work presents a reaction mechanism for oxygen plasmas, i.e. a set of reactions and corresponding rate coefficients that are validated against benchmark experiments. The kinetic scheme is validated in a DC glow discharge for gas pressures of 0.2–10 Torr and currents of 10–40 mA, using the 0D LisbOn KInetics simulation tool and available experimental data. The comparison comprises not only the densities of the main species in the discharge—

O
2

(

X

3

Δ

g

−

)

,

O
2

(

a
1

Δ

g

)

,

O
2

(

b
1

Σ

g
+

)

and

O

(
3

P
)

—but also the self-consistent calculation of the reduced electric field and the gas temperature. The main processes involved in the creation and destruction of these species are identified. Moreover, the results show that the oxygen atoms play a dominant role in gas heating, via recombination at the wall and quenching of

O
2

(

X

3

Σ

g
−

,
v

)

vibrations and

O
2

electronically-excited states. It is argued that the development and validation of kinetic schemes for plasma chemistry should adopt a paradigm based on the comparison against standard validation tests, as it is done in electron swarm validation of cross sections.
Changing pattern of N2 dissociation in N2–Ar RF plasma during E–H mode transition
Authors: Mukherjee A , Chakraborty M , Sharma N , Saha P K
Published: July 2023

The behaviour of nitrogen plasma mixed with varying proportions of argon (10%–80%) is investigated under different RF discharge conditions. It is observed that at a relatively low RF power of 200 W (E-mode) the dissociation fraction (DF) of nitrogen increases with the growing concentration of argon, whereas the opposite happens for a higher RF power of 1000 W (H-mode), when the DF rapidly falls from a high value as the argon percentage starts to increase. This rising trend of DF closely follows the argon metastable fraction (MF) in the E-mode, and for the H-mode it is not followed until the argon percentage crosses the 20% mark. The electron density, temperature and electron energy probability function (EEPF) are obtained using a RF compensated Langmuir probe and to evaluate the vibrational and rotational temperatures, DF, MF etc, a separate optical emission spectroscopy technique is incorporated. At 5 × 10−3 mbar of working pressure and 10% argon content the EEPF profile reveals that the plasma changes from non-Maxwellian to Maxwellian as the RF power jumps from 200 W to 1000 W, and for a fixed RF power the high energy tail tends to move upwards with the gradual increment of argon. These observations are reverified theoretically by considering electron–electron collision frequency and electron bounce frequency as a function of electron temperature. Overall, all the major experimental phenomena in this study are explained in terms of EEPF profile, electron–electron collision effect, electron and gas temperature, electron density and argon metastable population.
A three-stage amplification piezoelectric-actuated micro-gripper with adjustable output displacement: design, modeling, and experimental evaluation
Authors: Xu Dongmei , Yang Fan , Yu Simiao , Xu Chao , Liu Xianglong , Zhao Zhiwei , Zhang Xuhui , Li Shuaitian , Yang Huixi , Lu Qi
Published: July 2023

With the development of science and technology, the performance requirements of micro-gripper are getting higher and higher. Therefore, this paper designs a new piezoelectric-driven micro-gripper with large and adjustable output displacement, which can adjust the output range and compensate the errors caused by flexible mechanism. By adjusting the output displacement, the micro-components of different sizes can be clamped. The three-stage amplification mechanism is adopted, which utilizes triangle and lever amplification. Using the pseudo-rigid body method, the flexible hinge is analyzed; the statics, kinematics and dynamics models are established. Through finite element method, the magnification ratio of the micro-gripper is obtained, then the structure of the micro-gripper is further optimized. The output displacement and the magnification of the single-arm of the micro-gripper under 135 V are 223.8 μm and 24.2 times, respectively. This paper provides a basis for the wide application of micro-gripper.
Photoelectric transport signals induced by the periodical B/P substitution of doped graphene half-metals
Authors: Zuo Xueying , Cheng Jingjing , Liang Yulin , Xu Fuming , Xing Yanxia
Published: July 2023

Using the nonequilibrium Green’s function combined with the density functional theory, we investigate the spin-resolved photoelectric current in ferromagnetic hydrogenated zigzag graphene nanoribbons with boron or phosphorus atom substitutions (B/P-ZGNRs). Our findings indicate that B/P substitution induces half-metallic or semiconducting characteristics, depending on the edge form and substituted atoms. Induced by linear polarized light, the spin-resolved photocurrent could reveal information of the band structure and the contribution of different orbitals to the transport processes. Photocurrent peaks at specific photon energies clearly indicate the band edge of B/P-ZGNRs, while its signs reflect the distribution of the transmission coefficient spectrum. In symmetrically hydrogenated B/P-ZGNRs, the px
orbital is found to be dominant. However, in asymmetric B/P-ZGNRs, the py
orbital can also be dominant. Furthermore, B/P substitution induces a narrow band near the Fermi level, leading to remarkable negative differential resistance. These findings suggest potential applications of B/P-ZGNRs in spintronic devices and micro photoelectric detection.
Coherent states on the circle: semiclassical matrix elements in the context of Kummer functions and the Zak transformation
Authors: Giesel Kristina , Winnekens David
Published: July 2023

We extend former results for coherent states on the circle in the literature in two ways. On the one hand, we show that expectation values of fractional powers of momentum operators can be computed exactly analytically by means of Kummer’s confluent hypergeometric functions. Earlier, these expectation values have only been obtained by using suitable estimates. On the other hand, we consider the Zak transformation not only to map harmonic oscillator coherent states to coherent states on the circle as it has been discussed before, but we also use the properties of the Zak transformation to derive a relation between matrix elements with respect to coherent states in

L

2

(
R
)

and L
2(S
1). This provides an alternative way for computing semiclassical matrix elements for coherent states on the circle. In certain aspects, this method simplifies the semiclassical computations in particular if one is only interested in the classical limit, that is the zeroth order term in the semiclassical expansion.
Theoretical study of 2D PbSe/Bi2Se3 heterojunctions as gas sensors for the detection of SO2 and Cl2
Authors: Zhang Jiwei , Pang Jianhua , Chen Hui , Wei Guang , Wei Songrui , Wang Kuanyi , Yan Jin
Published: July 2023

In this paper, we construct a two-dimensional PbSe/Bi2Se3 van der Waals heterojunction to study the adsorption of Cl2 and SO2 by this heterojunction. Based on the help of Bader charge, charge density difference diagram, and electron localization function, we find the following conclusions. Among the six configurations, three meet the requirements for semiconductor gas sensor detection materials, namely α-PbSe-Bi2Se3, β-PbSe-Bi2Se3, and Bi2Se3-γ-PbSe. The Bi surface of the configuration α-PbSe-Bi2Se3 does not break the Cl-Cl bond in the Cl2 molecule after the adsorption of Cl2, and the band gap of the adsorbed material is reduced by 73.1%. The band gap of the Pb surface of the α-PbSe-Bi2Se3, β-PbSe-Bi2Se3 and Bi2Se3-γ-PbSe configurations change significantly after the adsorption of SO2, directly changing from a narrow band gap to a metallic material with a low adsorption energy and easy desorption of SO2 from the adsorbed material. Therefore, the two-dimensional PbSe/Bi2Se3 van der Waals heterojunction has the potential to become a core detection material for Cl2 and SO2 gas sensors.