bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring Fresnel diffraction at a straight edge with a neural network
Authors: Finot Christophe , Boscolo Sonia 
Published: March 2022

Abstract
We describe a research project carried out with a group of undergraduate physics students and aimed at exploring the use of a neural network to study a classical problem in wave optics whose analytical solution is well known: the diffraction of light by the straight edge of an opaque semi-infinite screen. Through this exposure to machine learning, the students were able to appreciate the basic steps involved in a machine-learning process.
Using quantum mechanics for calculation of different infinite sums
Authors: Mali Petar , Rutonjski Milica , Radošević Slobodan , Pantić Milan , Pavkov-Hrvojević Milica 
Published: March 2022

Abstract
We demonstrate that a certain class of infinite sums can be calculated analytically starting from a specific quantum mechanical problem and using principles of quantum mechanics. For simplicity we illustrate the method by exploring the problem of a particle in a box. Twofold calculation of the mean value of energy for the polynomial wave function inside the well yields even argument p (p > 2) of Riemann zeta and related functions. This method can be applied to a wide class of exactly solvable quantum mechanical problems which may lead to different infinite sums. Besides, the analysis performed here provides deeper understanding of superposition principle and presents useful exercise for physics students.
V-pits formation in InGaN/GaN: influence of threading dislocations and indium content
Authors: Stránská Matějová Jana , Hospodková Alice , Košutová Tereza , Hubáček Tomáš , Hývl Matěj , Holý Václav 
Published: March 2022

Abstract
Two sets of InGaN/GaN MOVPE-grown samples were studied by high-resolution x-ray diffraction techniques together with statistical analysis of atomic force microscope images in order to determine the impact of In concentration and threading dislocations (TDs) density on the V-pit formation. It was shown that in our samples, the density of V-pits in the epilayer matched the TD density with a screw component in the substrate. Pure edge TDs do not affect the V-pit density. The In concentration influences the size of the V-pits, but not their density.
Plasma diagnostics and modeling of lithium-containing plasmas
Authors: Ono Toshisato , Ganguly Shreyashi , Tu Qiaomiao , Kortshagen Uwe R , Aydil Eray S 
Published: March 2022

Abstract
Thin-film deposition from chemically reactive multi-component plasmas is complex, and the lack of electron collision cross-sections for even the most common metalorganic precursors and their fragments complicates their modeling based on fundamental plasma physics. This study focuses on understanding the plasma physics and chemistry in argon (Ar) plasmas containing lithium bis (trimethylsilyl) amide used to deposit Li
x
Si
y
thin films. These films are emerging as potential solid electrolytes for lithium-ion batteries, and the Li-to-Si ratio is a crucial parameter to enhance their ionic conductivity. We deposited Li
x
Si
y
films in an axial flow-through plasma reactor and studied the factors that determine the variation of the Li-to-Si ratio in films deposited at various points on a substrate spanning the entire reactor axis. While the Li-to-Si ratio is 1:2 in the precursor, the Li-to-Si ratio is as high as 3:1 in films deposited near the plasma entrance and decreases to 1:1 for films deposited downstream. Optical emission from the plasma is dominated by Li emission near the entrance, but Li emission disappears downstream, which we attribute to the complete consumption of the precursor. We hypothesized that the axially decreasing precursor concentration affects the electron energy distribution function in a way that causes different dissociation efficiencies for the production of Li and Si. We used Li line intensities to estimate the local precursor concentration and Ar line ratios to estimate the local reduced electric field to test this hypothesis. This analysis suggests that the mean electron energy increases along the reactor axis with decreasing precursor concentration. The decreasing Li-to-Si ratio with axially decreasing precursor concentration may be explained by Li release from the precursor having lower threshold energy than Si release.
Breakdown strength improvement of polypropylene by introducing long-chain branched structures for film capacitors
Authors: Xiao Meng , Zhang Mengdie , Du Boxue , Ran Zhaoyu , Liu Haoliang , Qin Yawei 
Published: March 2022

Abstract
The breakdown strength of polypropylene (PP) for film capacitors drops sharply in a high-temperature environment, which would lead to capacitor insulation failure frequently. This paper proposes a method to improve the breakdown strength of PP at high temperatures by introducing long-chain branches (LCBs). Different from traditional linear PP, the results show that LCBs can increase the number of spherulites and refine the grains due to heterogeneous nucleation, resulting in a reduction in weak areas in the films and an increase in trap densities and energy levels in long-chain branched polypropylene (LCBPP). In addition, the higher melt strength of LCBPP indicates that LCBs promote entanglement between molecular chains and hinder the sliding of chains, thereby reducing the influence of temperature on the free volume. Therefore, compared with PP, the conductivity of LCBPP is lower at high temperatures, and the breakdown strength increases by 16.2% at 105 °C. This method provides an idea for improving the breakdown strength of PP films at elevated temperatures from the perspective of regulating the microstructure.
Laser-induced THz magnetism of antiferromagnetic CoF2
Authors: Formisano F , Dubrovin R M , Pisarev R V , Kalashnikova A M , Kimel A V 
Published: March 2022

Abstract
Excitation, detection, and control of coherent THz magnetic excitation in antiferromagnets are challenging problems that can be addressed using ever shorter laser pulses. We study experimentally excitation of magnetic dynamics at THz frequencies in an antiferromagnetic insulator CoF2 by sub-10 fs laser pulses. Time-resolved pump-probe polarimetric measurements at different temperatures and probe polarizations reveal laser-induced transient circular birefringence oscillating at the frequency of 7.45 THz and present below the Néel temperature. The THz oscillations of circular birefringence are ascribed to oscillations of the magnetic moments of Co2+ ions induced by the laser-driven coherent E

g
phonon mode via the THz analogue of the transverse piezomagnetic effect. It is also shown that the same pulse launches coherent oscillations of the magnetic linear birefringence at the frequency of 3.4 THz corresponding to the two-magnon mode. Analysis of the probe polarization dependence of the transient magnetic linear birefringence at the frequency of the two-magnon mode enables identifying its symmetry.
Nonequilibrium Green’s function method for phonon heat transport in quantum system
Authors: Zeng Yu-Jia , Ding Zhong-Ke , Pan Hui , Feng Ye-Xin , Chen Ke-Qiu 
Published: March 2022

Abstract
Phonon heat transport property in quantum devices is of great interesting since it presents significant quantum behaviors. In the past few decades, great efforts have been devoted to establish the theoretical method for phonon heat transport simulation in nanostructures. However, modeling phonon heat transport from wavelike coherent regime to particlelike incoherent regime remains a challenging task. The widely adopted theoretical approach, such as molecular dynamics, semiclassical Boltzmann transport equation, captures quantum mechanical effects within different degrees of approximation. Among them, Non-equilibrium Green’s function (NEGF) method has attracted wide attention, as its ability to perform full quantum simulation including many-body interactions. In this review, we summarized recent theoretical advances of phonon NEGF method and the applications on the numerical simulation for phonon heat transport in nanostructures. At last, the challenges of numerical simulation are discussed.
Reciprocal-FDK reconstruction for x-ray diffraction computed tomography
Authors: Liang Kaichao , Zhang Li , Xing Yuxiang 
Published: March 2022

Abstract

Objective. X-ray diffraction (XRD) technology uses x-ray small-angle scattering signal for material analysis, which is highly sensitive to material inter-molecular structure. To meet the high spatial resolution requirement in applications such as medical imaging, XRD computed tomography (XRDCT) has been proposed to provide XRD intensity with improved spatial resolution from point-wise XRD scan. In XRDCT, 2D spatial tomography corresponds to a 3D reconstruction problem with the third dimension being the XRD spectrum dimension, i.e. the momentum transfer dimension. Current works in the field have studied reconstruction methods for either angular-dispersive XRDCT or energy-dispersive XRDCT for small samples. The approximations used are only suitable for regions near the XRDCT iso-center. A new XRDCT reconstruction method is needed for more general imaging applications. Approach. We derive a new FDK-type reconstruction method (Reciprocal-FDK) for XRDCT without limitation on object size. By introducing a set of reciprocal variables, the XRDCT model is transformed into a classical cone-parallel CT model, which is an extension of a circular-trajectory cone-beam CT model, after which the FDK method is applied for XRDCT reconstruction. Main results. Both analytical simulation and Monte Carlo simulation experiments are conducted to validate the XRDCT reconstruction method. The results show that when compared to existing analytical reconstruction methods, there are improvements in the proposed Reciprocal-FDK method with regard to relative structure reconstruction and XRD pattern peak reconstruction. Since cone-parallel CT does not satisfy the data completeness condition, cone-angle effect affects the reconstruction accuracy of XRDCT. The property of cone-angle effect in XRDCT is also analyzed with ablation studies. Significance. We propose a general analytical reconstruction method for XRDCT without constraint on object size. Reciprocal-FDK provides a complete derivation and theoretical support for XRDCT reconstruction by analogy to the well-studied cone-parallel CT model. In addition, the intrinsic problem with the XRDCT data model and the corresponding reconstruction error are discussed for the first time.
Halides formation dynamics in nanosecond and femtosecond laser-induced breakdown spectroscopy
Authors: Bordel N , Fernández-Menéndez L J , Méndez-López C , González-Gago C , Pisonero J 
Published: March 2022

Abstract
Laser-induced breakdown spectroscopy (LIBS) is an analytical technique based on the measurement of the emitted radiation coming from a laser-induced plasma (LIP) created after irradiation of a sample by a short-duration laser pulse. Research on molecular presence in LIPs has increased because the use of molecular emission has proven an encouraging way to improve LIBS abilities. LIPs are dynamic plasmas with fast time and spatial evolutions, in which atoms and molecules can follow different paths in their evolution and distribution. Molecular creation mechanisms within LIPs are still a challenging issue under investigation and the prevalence of some specific mechanisms are dependent on experimental conditions (sample nature, laser parameters, surrounding atmosphere…). In this work, different time and spatially solved experiments were carried out in ns- and fs-LIBS to investigate the dynamics of alkaline-earth (Ca) halide (F) diatomic molecule formation. Experiments were carried out on powdered CaF2 samples for both ns- and fs-LIBS. The effects of a gas flow (air, He, Ar) over the plume are investigated for ns-LIBS. Nebulization-modified ns-LIBS experiments in which the alkaline-earth element is externally added to the plasma plume as an aerosol were carried out on (C2F4)
n
samples. The spatial separation between atomic and molecular emission distribution was found to take place with and without external modifications over the ns-LIP. Behavior in fs-LIPs was determined to differ significantly from analogous experiments with nanosecond lasers, but temporal optimization remains the optimum method for molecular detection as spatial separation was not found to provide any remarkable advantage.
Quantitative analysis of edge breakdown effect of Geiger mode avalanche photo-diodes utilizing optical probe scanning method
Authors: He Tingting , Yang Xiaohong , Tang Yongsheng , Wang Rui , Liu Yijun 
Published: March 2022

Abstract
Planar InGaAs/InP avalanche photo diodes (APDs) are preferred single-photon detectors in the near-infrared region. They are usually fabricated using the double-diffusion method to avoid edge breakdown. However, this effect cannot be avoided completely as the bias voltage increases in the Geiger mode (GM). In this study, the influence of the deep diffusion window diameter on the premature edge breakdown of GM APDs was quantitatively analyzed using optical probe scanning method. Both numerical simulations and experimental measurements were performed. The electric field and dark current distribution, and the photon current under different optical input positions were numerically simulated. APDs with different deep diffusion window diameters were fabricated and tested to measure the photon current response. According to the normalized scanning photo current, we find that premature edge breakdown diminishes as the diffusion diameter of the device decreases. The position of the maximum electric field gradually shifted to the center as the diameter of the device decreased, and this shift gradually increased as the diameter decreased. The influence of edge breakdown was found to be avoided on the APD with a diameter of 10 μm, indicated by the avalanche gain reaching the maximum at the center, and the overlapping of optical and maximum electric gain regions is realized, which is crucial for high detection efficiency and low dark count of single photon detection.
60-GHz third-order on-chip bandpass filter using GaAs pHEMT technology
Authors: Xu Kai-Da , Weng Xiaoyu , Li Jianxing , Guo Ying-Jiang , Wu Rui , Cui Jianlei , Chen Qiang 
Published: March 2022

Abstract
A 60 GHz third-order on-chip bandpass filter (BPF) based on half-mode substrate integrated waveguide (HMSIW) cavity is synthesized using GaAs pHEMT technology. Two coupling slots are etched to divide the HMSIW cavity into three resonators, and then a third-order Chebyshev BPF is designed with predicted transmission zero, return loss and bandwidth through the synthesis method. The theoretical and extracted external quality factor and coupling coefficients are used to determine the dimensions of the BPF. For demonstration, a BPF sample with a bandwidth of 29.2% is fabricated, and its simulations and measurements are in good agreement.
Boron based new high entropy alloy superconductor Mo0.11W0.11V0.11Re0.34B0.33
Authors: Motla Kapil , Soni V , Meena P K , Singh R P 
Published: March 2022

Abstract
Superconducting high entropy alloys (HEAs) are new members of disordered superconductors. We report the synthesis and investigation of a new superconducting high entropy alloy Mo0.11W0.11V0.11Re0.34B0.33 (MWVRB). It crystallized in the tetragonal CuAl2 crystal structure with space group (I4/mcm). Comprehensive transport, magnetization and heat capacity measurements confirmed bulk type-II superconductivity having transition temperature T
C
= 4.0 K. The low temperature electronic specific heat suggests a fully gapped superconducting state in the weak coupling limit.
Synchronization of a genetic oscillator with the cell division cycle
Authors: Knotz Gabriel , Parlitz Ulrich , Klumpp Stefan 
Published: March 2022

Abstract
Genetic circuits that control specific cellular functions are never fully insulated against influences of other parts of the cell. For example, they are subject to periodic modulation by the cell cycle through volume growth and gene doubling. To investigate possible effects of the cell cycle on oscillatory gene circuits dynamics, we modelled a simple synthetic genetic oscillator, the repressilator, and studied hallmarks of the resulting nonlinear dynamics. We found that the repressilator coupled to the cell cycle shows typical quasiperiodic motion with discrete Fourier spectra and windows in parameter space with synchronization of the two oscillators, with a devil’s stair case indicating the Arnold tongues of synchronization. In the case of identical parameters for the three genes of the repressilator and simultaneous gene duplication, we identify two classes of synchronization windows, symmetric and asymmetric, depending on whether the trajectories satisfy a discrete three-fold rotation symmetry, corresponding to cyclic permutation of the three genes. Unexpectedly changing the gene doubling time revealed that the width of the Arnold tongues is connected to that three-fold symmetry of the synchronization trajectories: non-simultaneous gene duplication increases the width of asymmetric synchronization regions, for some of them by an order of magnitude. By contrast, there is only a small or even a negative effect on the window size for symmetric synchronization. This observation points to a control mechanism of synchronization via the location of the genes on the chromosome.
Multifrequency superscattering driven by symmetry-reduced resonators
Authors: Shamkhi H. K. , Canós Valero A. 
Published: March 2022

Abstract
We unveil novel mechanisms to achieve superscattering by investigating the resonances’ profile of non-Hermitian Hamiltonian structures lacking spherical symmetry. We show that superscattering can be obtained within a single scattering channel due to a contribution of a single strongly-coupled mode. Such phenomenon can’t be observed in Mie-based resonators. We then spatially and spectrally engineer modes of multi-resonators in a cluster to realize broadband superscattering with ultra-strong resonances at several frequency points.
Self-assembling plasmonic film of different-sized gold nanoparticles as a SERS substrate: the optimization study
Authors: Maleeva K. A. , Baranov M. A. , Bogdanov K. V. 
Published: March 2022

Abstract
The features of improving self-assembled films based on different-sized gold particles were investigated in this work. A study of the SERS signal was carried out to compare SPF samples consisting of gold nanoparticles of different sizes. For this purpose, colloids with different particle sizes were synthesized. These are spherical particles 20 nm and 40 nm in diameter and lamellar particles with an approximate size of 60x40x15 nm. Optimization of the concentration of the self-assembly agent of the reaction mixture in the preparation of the self-assembled plasmon film (SPF) has been carried out. The concentration of the self-collecting agent in the organic phase, at which the maximum values of the SERS enhancement of the signal were observed, is 10−5 M. The showing the reproducibility of the SERS signal for samples with the maximum enhancing of the SERS signal value is close for the all the studied particle sizes consisted SPF.
Challenges in the Additive Manufacture of Single and Multi-Core Optical Fibres
Authors: Canning J. , Chu Y. , Luo Y. , Peng G.D. , Zhang J. 
Published: March 2022

Abstract
Single and multi-core preforms doped with Bi and Er are fabricated using additive manufacture and drawing into optical fibre. We observe an increasing trend towards shape distortion with increasing number of cores. This is explained by noting that the composite effective softening point falls as the number of doped cores rises. The use of a silica cladding tube elevates the drawing temperature unnecessarily.
Systematic errors of THz absorption gas spectroscopy due to interference in a multi-pass cell
Authors: Semenova A. V. , Anfertev V. A. , Yablokov A. A. , Knyazeva T. D. 
Published: March 2022

Abstract
Multi-pass spectroscopic absorption cells are commonly used in gas spectroscopy to increase the sensitivity of the measurements. The possibility of systematic errors of such measurements was shown in this paper, even for the case when intrinsic transmittance of the cell alters weakly on the line width. The errors could be manifested both in perturbation of the shape of the absorption line and in the sufficient overestimation or underestimation of the absorption strength.
Towards plasmon mapping of SERS-active Ag dewetted nanostructures using SPELS
Authors: Beshr M , Dexter E , Tierney P E , Meade A D , Murphy S , Amarandei G 
Published: March 2022

Abstract
Thermal dewetting of silver thin flm can lead to SERS-active Ag nanoparticles. Here, we report our progress towards using scanning probe energy loss spectroscopy (SPELS) to map the plasmonic behaviour of SERS-active Ag nanoparticles (NP) by investigating NPs produced through the dewetting study of Ag thin flms on SiO2/Si and Ti/SiO2/Si substrates. The nanoparticles size and spatial distribution were controlled by the deposition and thermal annealing parameters. The results of preliminary SPELS measurements of these structures, alongside SERS data show that there is a correlation between the Raman enhancement and the nanoparticle size and interparticle spacing.
Enhanced Photocatalytic Activity of ZnO Nanorods/(Graphene Oxide, Reduced Graphene Oxide) for Degradation of Methyl Orange Dye
Authors: Sánchez Luis A. , Huayta Brian E. , Ramos Pierre G. , Rodriguez Juan M. 
Published: March 2022

AbstractZnO has been well-known as a significant photocatalyst material due to its high surface area, efficient charge transport, and superior photosensitivity. Even though photocatalysis using bare ZnO NRs is useful in pollutant remediation, two main drawbacks scale down their performance as photocatalysts. First, ZnO NRs absorb mainly the UV light, which compromises a small portion of the solar spectrum, and second, the high recombination rate in the ZnO NRs prevents the path of electron-hole outward and then reduces the photocatalysis efficiency. In this work, ZnO-NRs, ZnO-NRs/Graphene Oxide (GO), and ZnO-NRs/Reduced Graphene Oxide (rGO) array composites were vertically grown on conductive glass substrates of SnO2:F (FTO). The films were synthesized by hydrothermal method using ZnO seed layers deposited by spray pyrolysis technique. The nanosheets of GO and rGO were anchored onto the surface of the as-prepared ZnO-NRs by using the spray deposition technique (SDT). The photocatalytic activity of these materials was studied by analyzing the degradation of methylene orange (MO) in an aqueous solution under ultraviolet light, and we found that the decoration of ZnO-NRs with nanosheets of GO and rGO resulted in a significant enhancement of the photocatalytic degradation efficiency, where ZnO-NRs/rGO are more efficient than ZnO-NRs/GO and the latter better than pure ZnO-NRs.
A 20 Gbps PAM4 data transmitter ASIC for particle physics experiments
Authors: Zhang L. , Cruda E.M. , Chao C-P. , Chen S-W. , Deng B. , Francisco R. , Gong D. , Guo D. , Hou S. , Huang G. , Huang X. , Kulis S. , Li C.-Y. , Liu C. , Liu E.R. , Liu T. , Moreira P. , Prinzie J. , Sun H. , Sun Q. , Sun X. , Wong G. , Yang D. , Ye J. , Zhang W. 
Published: March 2022

Abstract
We present the design and test results of a novel data transmitter ASIC operating up to 20.48 Gbps with 4-level Pulse-Amplitude-Modulation (PAM4) for particle physics experiments. This ASIC, named GBS20, is fabricated in a 65 nm CMOS technology. Two serializers share a 5.12 GHz Phase Locked Loop (PLL) clock. The outputs from the serializers are combined into a PAM4 signal that directly drives a Vertical-Cavity-Surface-Emitting-Laser (VCSEL). The input data channels, each at 1.28 Gbps, are scrambled with an internal 27-1 Pseudo-Random Binary Sequence (PRBS), which also serves as a frame aligner. GBS20 is tested to work at 10.24 and 20.48 Gbps with a VCSEL-based Transmitter-Optical-Subassembly (TOSA). The power consumption of GBS20 is below 238 mW and reduced to 164 mW in the low-power mode.