bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining machine learning and Mie theory to simplify particle characterization inside microchannels
Authors: Taei Amirmohammad , Karimzadeh Rouhollah , Jahanbakhshian Mohammadmehdi
Published: September 2023

In recent decades, particle characterization has been one of the most widely used achievements. The article presents a method to simplify the setup using unsupervised machine learning techniques, such as K-means, K-medoids, and Hierarchical clustering. Utilizing these three methods together, our approach can accurately measure particle diameter with a precision of 0.1 μm and a refractive index of 0.001 using only a laser and a camera without the need for complex alignment of components. Furthermore, our method is capable of separating scattered signal images from background images.
An embedded cluster CASPT2 study of the Ce:YVO4 spectrum
Authors: Larsson Ernst D. , Veryazov Valera
Published: September 2023

Multiconfigurational theory, in combination with the embedded cluster approach, is a precise and ab initio approach to describe the electronic structure of solids. In this work, the spectrum of a Ce(III) dopant in YVO4 has been studied by complete active space perturbation theory of the second order (CASPT2), with the host material represented as a set of ab initio model potentials and point-charges. We assess the sensitivity of the spectrum to the size of both the embedded cluster size as well as the size of the electronic basis set. A comparison of our best computational model with experimental results shows that the embedding approach is robust and can accurately model the spectrum of low-concentration dopants in complex host materials.
Research on electromagnetic scattering characteristics of flexible stealth material based on its 3D model
Authors: Gao Xin , Wang Xiangwei , Peng Ruihui , Dou Zheng , Lv Yongsheng
Published: September 2023

With the widespread adoption of flexible stealth materials (FSMs) in radar stealth application, understanding their electromagnetic scattering information has become increasingly crucial. However, acquiring the electromagnetic scattering properties of FSMs solely through measurement can be challenging. Hence, this study proposes an electromagnetic scattering model for FSMs based on random undulating units formed by sweeping two parabola functions. Specifically, the multi-layer fast multipole method (MLFMM) is applied to calculate the model’s monostatic RCS within 8–12 GHz, enabling a comprehensive analysis of FSM’s electromagnetic scattering characteristics (ESCs). We fabricate an FSM sample for experimental validation and conduct meticulous measurements alongside theoretical calculations. Impressively, the calculated results exhibit relatively good agreement with the measured data, signifying our model’s reliability. Furthermore, by leveraging the proposed model and the MLFMM, we delve into the influence of various electromagnetic parameters, the undulating angle, and the size of undulation units on the ESCs of FSM. Our numerical results demonstrate that the ESCs of FSM exhibit regular variations in response to the changes in these parameters. In addition, we meticulously examine the interaction between electromagnetic waves and the material, further enriching our understanding of the observed results. This research provides valuable references for ESC investigation of flexible stealth material and radar stealth experimental design.
Electric field controlled perpendicular exchange bias in Ta/Pt/Co/IrMn/Pt heterostructure
Authors: Wang Mengxi , Li Meiling , Lu Yunhao , Xu Xiaoguang , Jiang Yong
Published: September 2023

Perpendicular exchange bias (PEB) is an essential effect of antiferromagnetic materials. It has the advantages over the in-plane exchange bias in application of magnetic random access memory (MRAM) technology, particularly in terms of higher packing density. The influence of the strain effect on PEB of Ta/Pt/Co/Ir20Mn80/Pt multilayers deposited on the piezoelectric substrate is studied in this work. It is found that the exchange bias field (Hex) can be regularly regulated by the strain effect introduced by the piezoelectric substrate. It indicates that the uncompensated spins at the interface of Ir20Mn80/Co can be reoriented under the strain effect, resulting in the variation of Hex. Furthermore, we propose a MRAM device structure based on the strain-mediated PEB, which enables field-free magnetization switching driven by the pure strain. Our study demonstrates the controllability of PEB and its application in spintronics, providing a method for the development of antiferromagnetic material-based next generation MRAM.
Determination of carbon nanotubes concentration by tabletop dynamic susceptometer
Authors: Pannetier Lecoeur Myriam , Boutet Léa , Pinault Mathieu , Solignac Aurélie , Bouillonnec Jonathan , Plancke Anaëlle , Mayne-L’Hermite Martine , Fermon Claude
Published: September 2023

Carbon nanotubes (CNTs) can be incorporated in various materials to enhance their mechanical or electrical properties. Information on their precise concentration and local distribution is difficult to access non-invasively. For example, electron microscopy studies require cutting of samples. Another way to measure the concentration of CNTs is by the magnetic susceptibility of the ferrocene present in the CNTs by the synthesis process, which can be performed on sample coupons on a vibrating sample magnetometer (VSM); VSM is a bulky laboratory instrument, and the size of the samples studied is constrained. In order to provide a technique that is fast, easy, cheap, and adaptable to the size of the samples, we have developed a benchtop device that measures the CNT concentration through an original inductive dynamic measurement of the ferrocene magnetic susceptibility. We present the method for extracting CNT concentrations and show the results obtained on cement matrices with CNT concentrations of the order of a few percent.
Pressure-induced phase transition in cubic Yb2O3 and phase transition enthalpies
Authors: Jiang Sheng , Zhang Jichao , Wang Lingrui , Lin Chuanlong , Yan Shuai , Liu Jing , Li Aiguo , Tai Renzhong
Published: September 2023

The high pressure structural evolution of cubic Yb2O3 has been studied using in situ synchrotron angle dispersive x-ray diffraction in combination with diamond anvil cell techniques up to 44.1 GPa. The XRD measurements revealed an irreversible reconstructive phase transition from cubic to monoclinic Yb2O3 at 11.2 GPa and extending up to 28.1 GPa with ∼8.1% volume collapse and a subsequent reversible displacive transition from monoclinic to hexagonal phase starting at 22.7 GPa. The monoclinic phase coexists with the hexagonal phase up to 44.1 GPa. After pressure releases, the hexagonal Yb2O3 reverts to the monoclinic structure. The second-order Birch–Murnaghan equation of state fit to the pressure–volume data yields a bulk modulus of 201 (4), 187 (6), and 200 (4) GPa for the cubic, monoclinic, and hexagonal phases, respectively. Furthermore, the effects of the hydrostatic pressure state on the diffraction patterns, bulk modulus, and onset transition pressure of Yb2O3 under high pressure have been discussed. It is concluded that the bulk modulus of the cubic Ln2O3 phase increases with decreasing cation radius due to lanthanide contraction. Another important work in this study is the determination of the enthalpies of the cubic to monoclinic and monoclinic to hexagonal phase transitions of Yb2O3 of 37.0 and 17.4 kJ/mol, respectively, based on the basic thermodynamic equations and using the onset transition pressures and corresponding volume changes obtained from high pressure XRD experiments.
Mitigation of deceleration-phase Rayleigh–Taylor instability growth in inertial confinement fusion implosions
Authors: Lawrence Yousef , Goncharov Valeri , Woo Ka Ming , Trickey William , Igumenshchev Igor
Published: September 2023

Rayleigh–Taylor growth during shell deceleration is one of the main limiting factors for target performance in inertial confinement fusion implosions. Using analytical scaling laws and hydrodynamic simulations, we show that such amplification can be mitigated by reducing the initial mass density in the central target region. The perturbation growth reduction is caused by a smaller hot-spot convergence ratio during deceleration, increased density scale length, and enhanced ablation stabilization. The required central density reduction can be achieved using the dynamic shell formation concept.
Thermally stable piezoelectric fiber based on perfluoroalkoxy alkane piezoelectret with a lotus root structure
Authors: Zhou Lian , Hu Qianqian , Shi Jiayou , Ling Quan , Yuan Yujin , Zhang Tongyan , Zhang Xiaoqing
Published: September 2023

Advanced functional fibers, which can endow common textiles with specific functionalities by traditional weaving processes without losing their basic features, including flexibility, breathability, and wash ability, are desired in flexible and wearable devices. However, the performance of piezoelectric wire sensors in previous studies has been unsatisfactory, especially in harsh environments. This article reports a thermally stable thin piezoelectric fiber with a lotus root structure, consisting of a core electrode, a perfluoroalkoxy alkane piezoelectret layer, a ground/shield electrode, and an outer jacket. The specific structure together with a small diameter of 0.4 mm makes such fiber sensors very flexible and suitable to be woven into clothing or integrated into thin substrates. The piezoelectric sensitivity of the fibers, up to 1.50 pC/N at 0.25 MPa, is achieved and very stable in a broad operating temperature ranging from −79 to 150 °C, showing a promising application prospect in extreme environments. The fabrics and socks woven with such fibers can detect various motions, demonstrating their practicability in smart clothing for ordinary applications such as rehabilitation and gait analysis and special purposes such as functional clothing for astronauts and firefighters who may expose to very low- or high-temperature environments.
Non-uniform Gd distribution and magnetization profiles within GdCoFe alloy thin films
Authors: Inyang O. , Swindells C. , Rianto D. , Bouchenoire L. , Morris R. J. H. , Merkulov A. , Caruana A. , Kinane C. , Hase T. P. A. , Atkinson D.
Published: September 2023

Rare earth (RE):transition metal (TM) ferrimagnetic alloys continue to attract significant attention for spintronics. This work focuses on the elemental distribution of RE and TM elements throughout the thickness of nominally uniform films and the resulting spatial variations of the magnetization within these layers. Samples of CoFe alloyed with Gd were studied using secondary ion mass spectroscopy, polarized neutron reflectometry, and x-ray resonant magnetic reflectivity. The samples were grown by magnetron co-sputtering to control the RE:TM alloy ratio of the ferrimagnetic layer, which was combined with W and Pt layers as either under or over-layers to create sample structures such as W/Gdx(Co70Fe30)100−x/Pt, where x = 0, 8, and 23 at. %. Results show that uniformly deposited thin-films have a significant variation in the distribution of the TM and RE through the film thickness, and this leads to a spatial distribution in the net magnetization profile and a non-uniform Gd magnetization profile within the layer. These findings have implications for the application RE:TM alloys in spintronics as they may impact the perpendicular magnetic anisotropy, the ferrimagnetic compensation temperature, and interfacial spin transport.
Wideband image-reject RF channelization based on soliton microcombs (invited paper)
Authors: Ding Jiewen , Wu Yifan , Yang Huashan , Zhang Chao , Zhang Yifei , He Jijun , Zhu Dan , Pan Shilong
Published: September 2023

Wideband radio frequency (RF) channelization is essential for the reception and detection of cross-band RF signals in various applications, including communications, radar, and spectrum sensing. However, digital channelizers are inefficient at performing RF channelization over a working bandwidth above 10 GHz. Meanwhile, current photonic RF channelizers face challenges in simultaneously considering a wideband, multi-channel, and a high crosstalk suppression ratio. In this work, we proposed and demonstrated a wideband image-reject RF channelization scheme based on integrated dual-soliton microcombs. The dual-soliton microcombs are used for RF spectral copies and heterodyne detection, respectively. Supported by image-reject mixers, the RF channelization is verified with an 8–37 GHz working bandwidth, a 1.2 GHz channel bandwidth, and 25 channels. The image suppression ratio is higher than 34 dB for single-tone signals and 20 dB for wideband signals. Our approach provides an innovative architecture of integrated photonic RF channelizers with high performance, which can benefit a wide range of RF applications by miniaturizing the systems.
Fundamental solutions to ship-motion problems with viscous effects
Authors: Chen Xiaobo
Published: September 2023

The fundamental solution of the ship-motion problem, known as the ship-motion Green function associated with a pulsating and translating source, is formulated and analyzed based on the weakly damped free-surface flows. The inclusion of viscous effects modifies the dispersion relation, resulting in the existence of three wavenumbers instead of two, as observed in inviscid fluids. The Green function with viscous effects is examined in relation to these three complex wavenumbers, and novel formulations of Havelock's type are developed. Special attention is paid to the analysis of several numerical issues and the treatment to resolve them. The wavenumber integral function involved is analyzed using contour integration in the complex plane, leading to a classical formulation that includes the exponential integral function and a constant function representing the contributions of residues. Additionally, new series and Taylor expansions are developed to facilitate the integration of the ship-motion Green function on ship hull and the free surface. Furthermore, derivatives and antiderivatives of the wavenumber integral function have been obtained for all three formulations. Numerical examples are included to illustrate the soundness of the formulations and their efficiency in numerical evaluations. At the critical frequency, in particular, the Green function with viscous effects is shown to be finite and its magnitude decreases along the horizontal distance from the source. Finally, benefits of introducing viscous effects in the fundamental solution are examined and emphasized in the discussion and conclusions.
Two- and three-photon absorption in bulk CuI
Authors: Müller Andreas , Henn Sebastian , Krüger Evgeny , Blaurock Steffen , Krautscheid Harald , Grundmann Marius , Sturm Chris
Published: September 2023

We report on photoluminescence emission in copper iodide bulk single crystals induced by two- and three-photon absorption around 1.525 eV. These non-linear optical processes are investigated utilizing density-dependent, steady-state, as well as time-resolved photoluminescence spectroscopy as a function of the excitation energy. Using an excitation energy that corresponds to half of the bandgap energy, the observed photoluminescence intensity dependence on the excitation power shows an almost parabolic behavior. By further reduction of the photon energy, a cubic contribution is observable, which increases with decreasing excitation energy. The experimentally observed behavior can be well described by taking into account two- and three-photon absorption. By a simultaneous analysis of the intensity behavior for all used excitation energies, we determined a ratio between the two- and three-photon absorption cross section on the order of σ0(3)/σ0(2)≈10−28 cm2s.
Stable Janus monolayer MoSHx (0.5 ≤ x ≤ 2)
Authors: Huang Zhijing , Aguilar Jose Manuel Perez , Zeng Shuming , Tu Yusong , Gu Zonglin
Published: September 2023

MoSH is a representative example of a Janus two-dimensional monolayered system consisting of a molybdenum atomic layer sandwiched between sulfur and hydrogen atomic layers. Extensive experimental and theoretical efforts have suggested the great promise of the MoSH material, but the validity of the MoSH model (with a Mo–S–H ratio of 1:1:1) remains uncertain. While various experiments have established the Mo-to-S ratio to be close to 1:1, the hydrogen content has remained elusive even with the use of state-of-the-art characterization techniques due to its lightweight nature. In this study, we present a theoretical investigation aiming to determine the positions and ratios of the hydrogen atoms on MoSHx (with x ranging from 0 to 3) as well as assess their structural stability. By evaluating the energetic, mechanical, and thermodynamic properties, we confirm the existence of stable MoSHx structures within a critical range of hydrogen atom ratios, specifically 0.5 ≤ x ≤ 2.0. Additionally, as the hydrogen atom ratio increases, we observe a transition in the preferred adsorption sites of hydrogen atoms from the center of the hexagonal ring composed of molybdenum and sulfur atoms to the upper region of the molybdenum atoms. This study offers critical insight into the structural characteristics and stability of Janus monolayer MoSHx, contributing to the advancement and application of Janus MoSHx in various fields.
Research on the dynamic positioning of remotely operated vehicles applied to underwater inspection and repair of hydraulic structures
Authors: Tian Baoqiang , Liu Chuan , Guo Jiawei , Yuan Shifeng , Wang Lijun , Xu Zhantang
Published: September 2023

Hydraulic structures (such as dams and aqueducts) can suffer from damages, such as cracks and collapse due to natural aging as well as the impact of natural disasters (such as earthquakes and floods). Determining underwater damage is generally not easy because of significant concealment and safety hazards. Remotely operated vehicles (ROVs) have gradually become capable assistants for the regular underwater maintenance of hydraulic structures. With disturbances from undercurrents and propeller reactions, achieving precise positioning of ROVs has always been a complicated technical problem, and it is also one of the important factors affecting underwater inspections and repair accuracy. To address the environmental disturbances during ROV dynamic positioning, a fuzzy predictive control algorithm combining fuzzy control and model predictive control is proposed in this paper. This algorithm can dynamically adjust the power output of propellers in real-time according to the undercurrent data measured by sensors and carry out differential correction until the ROV reaches the predetermined position. Moreover, the aim of this paper is to analyze disturbances in the longitudinal (X), lateral (Y), and depth (Z) directions during the motion of the ROV. The parameters are adjusted through the algorithm to simulate the dynamic positioning of the ROV's spatial movements. By setting different external environmental conditions, the power adjustment strategy and different dynamic positioning performances of ROVs can be obtained to enhance the adaptability of ROVs in complex environments and their stability in underwater inspection and repair and improve their underwater operation quality and efficiency.
Ultra-stable and low-divergence high-power antimonide light emitters with on-chip mode filter
Authors: Shi Jianmei , Yang Chengao , Wang Tianfang , Chen Yihang , Yu Hongguang , Zhang Yu , Wu Donghai , Xu Yingqiang , Ni Haiqiao , Niu Zhichuan
Published: September 2023

Antimonide semiconductor laser diodes with high brightness are ideal light sources for a variety of applications. However, the traditional structure of broad-area (BA) lasers with high-power output is normally accompanied by a multi-lobed far field profile and large lateral divergence. In this paper, we put up an on-chip microstructure for mode filtering. The excellent mode control capability is doubly confirmed by optical field simulations and complete device measurements. The optimized device shows an enhanced continuous-wave output power in exceeding of 1.3 W at room temperature, along with a reduced threshold current and increased peak power conversion efficiency. Moreover, it exhibits an ultra-stable lateral far field with a 45.6% reduction in divergence and a notable 75.5% improvement in current dependence compared with conventional BA diode lasers. The minimum divergence is as low as 5.64° for full width at half maximum definition.
Plasmons in AlGaN/GaN grating-gate structure probing with 300 K background illumination
Authors: Dub M. , But D. B. , Sai P. , Ivonyak Yu. , Słowikowski M. , Filipiak M. , Cywinski G. , Knap W. , Rumyantsev S.
Published: September 2023

We show that terahertz plasmons in AlGaN/GaN grating-gate structures efficiently modulate the reflection of room temperature thermal radiation, leading to spectra that are in agreement with the measurements of plasmon absorption using high-power external sources. For typical samples of a few square millimeters in size, the reflected radiation intensity is relatively weak, and measurements need the use of gate voltage plasmon modulation and lock-in detection techniques. We show that unintentional use of lock-in techniques may lead to artifacts and demonstrate what kind of special precautions need to be taken into account. We show that drain voltage modulation also leads to modulation of the reflected thermal radiation by plasmons. Our results are of key importance for the research on new resonant plasmon-based terahertz sources because of the always present superposition of electrically excited terahertz emission and background radiation reflected from the structures.
Classical and Bayesian estimation for the extended odd Weibull power Lomax model with applications
Authors: Alsadat Najwan , Elgarhy Mohammed , Tolba Ahlam H. , Elwehidy Ahmed S. , Ahmad Hijaz , Almetwally Ehab M.
Published: September 2023

A new continuous distribution called the extended odd Weibull power Lomax (ExOW-POLO) distribution is introduced and studied. Numerous reliability and statistical features are derived. Additionally studied are point estimates using maximum likelihood, maximum product space, least square, weighted least square, and Bayesian estimation techniques. The mean square error and bias of the maximum likelihood and Bayesian parameter estimators are computed using simulation approaches, such as Markov chain Monte Carlo. Two intraocular pressure (IOP) real datasets were conducted between January 2015 and February 2018 on 49 patients (84 eyes) under the age of two who presented with primary congenital glaucoma to the Paediatric Ophthalmology Unit of the Mansoura Ophthalmic Center of Mansoura University in Egypt have been fitted the ExOW-POLO distribution. Comparing the properties of the proposed distribution’s fitting of the data to recognized extensions of the Lomax distribution. The analysis revealed that the most well-known extensions of Lomax distribution were made by the ExOW-POLO distribution outfit. In addition, the correlation measures and independent sample test for the two IOP real datasets are introduced with (A) Levene’s test for equality of variances for the two cases and (B) the t-test for equality of means. For Levene’s test for equality of variances: the null hypothesis is that equal variances are assumed and the alternative hypothesis is that equal variances are not assumed.
Friction patterns guide actin network contraction
Authors: Colin Alexandra , Orhant-Prioux Magali , Guérin Christophe , Savinov Mariya , Cao Wenxiang , Vianay Benoit , Scarfone Ilaria , Roux Aurélien , De La Cruz Enrique M. , Mogilner Alex , Théry Manuel , Blanchoin Laurent
Published: September 2023

The shape of cells is the outcome of the balance of inner forces produced by the actomyosin network and the resistive forces produced by cell adhesion to their environment. The specific contributions of contractile, anchoring and friction forces to network deformation rate and orientation are difficult to disentangle in living cells where they influence each other. Here, we reconstituted contractile actomyosin networks in vitro to study specifically the role of the friction forces between the network and its anchoring substrate. To modulate the magnitude and spatial distribution of friction forces, we used glass or lipids surface micropatterning to control the initial shape of the network. We adapted the concentration of Nucleating Promoting Factor on each surface to induce the assembly of actin networks of similar densities and compare the deformation of the network toward the centroid of the pattern shape upon myosin-induced contraction. We found that actin network deformation was faster and more coordinated on lipid bilayers than on glass, showing the resistance of friction to network contraction. To further study the role of the spatial distribution of these friction forces, we designed heterogeneous micropatterns made of glass and lipids. The deformation upon contraction was no longer symmetric but biased toward the region of higher friction. Furthermore, we showed that the pattern of friction could robustly drive network contraction and dominate the contribution of asymmetric distributions of myosins. Therefore, we demonstrate that during contraction, both the active and resistive forces are essential to direct the actin network deformation.
PIF4 enhances the expression of
SAUR
genes to promote growth in response to nitrate
Authors: Pereyra Matías Ezequiel , Costigliolo Rojas Cecilia , Jarrell Anne F. , Hovland Austin S. , Snipes Stephen A. , Nagpal Punita , Alabadí David , Blázquez Miguel A. , Gutiérrez Rodrigo A. , Reed Jason W. , Gray William M. , Casal Jorge José
Published: September 2023

Nitrate supply is fundamental to support shoot growth and crop performance, but the associated increase in stem height exacerbates the risks of lodging and yield losses. Despite their significance for agriculture, the mechanisms involved in the promotion of stem growth by nitrate remain poorly understood. Here, we show that the elongation of the hypocotyl of
Arabidopsis thaliana
, used as a model, responds rapidly and persistently to upshifts in nitrate concentration, rather than to the nitrate level itself. The response occurred even in shoots dissected from their roots and required NITRATE TRANSPORTER 1.1 (NRT1.1) in the phosphorylated state (but not NRT1.1 nitrate transport capacity) and NIN-LIKE PROTEIN 7 (NLP7). Nitrate increased PHYTOCHROME INTERACTING FACTOR 4 (PIF4) nuclear abundance by posttranscriptional mechanisms that depended on NRT1.1 and phytochrome B. In response to nitrate, PIF4 enhanced the expression of numerous
SMALL AUXIN-UP RNA (SAUR)
genes in the hypocotyl. The growth response to nitrate required PIF4, positive and negative regulators of its activity, including AUXIN RESPONSE FACTORs, and SAURs. PIF4 integrates cues from the soil (nitrate) and aerial (shade) environments adjusting plant stature to facilitate access to light.
Real-time imaging of acoustic waves in bulk materials with X-ray microscopy
Authors: Holstad Theodor S. , Dresselhaus-Marais Leora E. , Ræder Trygve Magnus , Kozioziemski Bernard , Driel Tim van , Seaberg Matthew , Folsom Eric , Eggert Jon H. , Knudsen Erik Bergbäck , Nielsen Martin Meedom , Simons Hugh , Haldrup Kristoffer , Poulsen Henning Friis
Published: September 2023

The dynamics of lattice vibrations govern many material processes, such as acoustic wave propagation, displacive phase transitions, and ballistic thermal transport. The maximum velocity of these processes and their effects is determined by the speed of sound, which therefore defines the temporal resolution (picoseconds) needed to resolve these phenomena on their characteristic length scales (nanometers). Here, we present an X-ray microscope capable of imaging acoustic waves with subpicosecond resolution within mm-sized crystals. We directly visualize the generation, propagation, branching, and energy dissipation of longitudinal and transverse acoustic waves in diamond, demonstrating how mechanical energy thermalizes from picosecond to microsecond timescales. Bulk characterization techniques capable of resolving this level of structural detail have previously been available on millisecond time scales—orders of magnitude too slow to capture these fundamental phenomena in solid-state physics and geoscience. As such, the reported results provide broad insights into the interaction of acoustic waves with the structure of materials, and the availability of ultrafast time-resolved dark-field X-ray microscopy opens a vista of new opportunities for 3D imaging of materials dynamics on their intrinsic submicrosecond time scales.
Cooperative mechanisms underlie differences in myocardial contractile dynamics between large and small mammals
Authors: Patel Jitandrakumar R. , Park Kayla J.V. , Bradshaw Aidan S. , Phan Tuan , Fitzsimons Daniel P.
Published: September 2023

Ca2+ binding to troponin C (TnC) and myosin cross-bridge binding to actin act in a synergistic cooperative manner to modulate myocardial contraction and relaxation. The responsiveness of the myocardial thin filament to the activating effects of Ca2+ and myosin cross-bridge binding has been well-characterized in small mammals (e.g., mice). Given the nearly 10-fold difference in resting heart rates and twitch kinetics between small and large mammals, it is unlikely that the cooperative mechanisms underlying thin filament activation are identical in these two species. To test this idea, we measured the Ca2+ dependencies of steady-state force and the rate constant of force redevelopment (ktr) in murine and porcine permeabilized ventricular myocardium. While murine myocardium exhibited a steep activation-dependence of ktr, the activation-dependent profile of ktr was significantly reduced in porcine ventricular myocardium. Further insight was attained by examining force–pCa and ktr–pCa relationships. In the murine myocardium, the pCa50 for ktr was right-shifted compared with the pCa50 for force, meaning that increases in steady-state force occurred well before increases in the rate of force redevelopment were observed. In the porcine myocardium, we observed a tighter coupling of the force–pCa and ktr–pCa relationships, as evidenced by near-maximal rates of force redevelopment at low levels of Ca2+ activation. These results demonstrate that the molecular mechanisms underlying the cooperative activation of force are a dynamic property of the mammalian heart, involving, at least in part, the species- and tissue-specific expression of cardiac myosin heavy chain isoforms.
Superior white electroluminescent devices using nitrogen-doped carbon dots/TiO2 nanorods heterostructures
Authors: Chakrabarty Poulomi , Ghorai Arup , Pal Sourabh , Adak Deepanjana , Roy Baidyanath , Ray Samit K , Mukherjee Rabibrata
Published: September 2023

Nitrogen-doped carbon dots (NCDs), exhibiting strong yellow emission in aqueous solution and solid matrices, have been utilized for fabricating heterostructure white electroluminescence devices. These devices consist of nitrogen-doped carbon dots as an emissive layer sandwiched between an organic hole transport layer (PEDOT:PSS) and an array of rutile TiO2 nanorods, acting as an electron transport layer. Under an applied forward bias of 5 V, the device exhibits broadband electroluminescence covering the wavelength range of 390–900 nm, resulting in pure white light emission characteristics at room temperature. The result demonstrates the successful fabrication of all solution-processed, low-cost, eco-friendly NCDs-based LEDs with CIE (Commission Internationale d’Éclairage) coordinate of (0.31, 0.34) and color rendering index (CRI) > 90, which are close to ideal white light emission characteristics. The device functionalities are achieved based on defect-related NIR emission from TiO2 nanorods array and visible emission from nitrogen-doped carbon dots. This result paves a new opportunity to develop low-cost, solution-processed nitrogen-doped carbon dots based on warm White light emitting diodes with high CRI for large-area display and lighting applications.
Calculation and study for the growth process and electrical characteristics of the conductive filament in nanoscale resistance memory under current-driven mode
Authors: Ke Qing , Dai Yuehua
Published: September 2023

After investigating the behavior of ions during the growth of conductive filaments, we suggested a model for the growth process and electrical characteristics of the conductive filament under current-driven mode. In this model, the ionic displacement equation is derived by Arrhenius law, and a differential equation for the conductive filament growth has been established. We have also proved that the dielectric layer with the leakage current under current-driven mode can be equivalent to a parallel plate capacitor, which has a the equivalent dielectric constant. Consequently, the forming/set time of the device is gotten. At the same time, the kinetics process of ion motion is analyzed in detail, so that many microscopic parameters of the ion motion, such as the height of the potential barrier, the jump step, mobility and diffusion coefficient, can be obtained. Due to divalent and monovalent copper ions all participate in conduction, an equivalent copper ion Cuz+ is used for replacing both Cu+ and Cu2+, solving the computational complexity problem caused by multivalent metal ions. Finally, an equivalent circuit is proposed to calculate output voltage versus time characteristic. The calculation results of the model are consistent with experimental data.
Sub-second whole brain T2 mapping via multiband SENSE multiple overlapping-echo detachment imaging and deep learning
Authors: Li Simin , Kang Taishan , Wu Jian , Chen Weikun , Lin Qing , Wu Zhigang , Wang Jiazheng , Cai Congbo , Cai Shuhui
Published: September 2023

Objective. Most quantitative magnetic resonance imaging (qMRI) methods are time-consuming. Multiple overlapping-echo detachment (MOLED) imaging can achieve quantitative parametric mapping of a single slice within around one hundred milliseconds. Nevertheless, imaging the whole brain, which involves multiple slices, still takes a few seconds. To further accelerate qMRI, we introduce multiband SENSE (MB-SENSE) technology to MOLED to realize simultaneous multi-slice T2 mapping. Approach. The multiband MOLED (MB-MOLED) pulse sequence was carried out to acquire raw overlapping-echo signals, and deep learning was utilized to reconstruct T2 maps. To address the issue of image quality degradation due to a high multiband factor MB, a plug-and-play (PnP) algorithm with prior denoisers (DRUNet) was applied. U-Net was used for T2 map reconstruction. Numerical simulations, water phantom experiments and human brain experiments were conducted to validate our proposed approach. Main results. Numerical simulations show that PnP algorithm effectively improved the quality of reconstructed T2 maps at low signal-to-noise ratios. Water phantom experiments indicate that MB-MOLED inherited the advantages of MOLED and its results were in good agreement with the results of reference method. In vivo experiments for MB = 1, 2, 4 without the PnP algorithm, and 4 with PnP algorithm indicate that the use of PnP algorithm improved the quality of reconstructed T2 maps at a high MB. For the first time, with MB = 4, T2 mapping of the whole brain was achieved within 600 ms. Significance. MOLED and MB-SENSE can be combined effectively. This method enables sub-second T2 mapping of the whole brain. The PnP algorithm can improve the quality of reconstructed T2 maps. The novel approach shows significant promise in applications necessitating high temporal resolution, such as functional and dynamic qMRI.
Constraining quadratic f(R) gravity from astrophysical observations of the pulsar J0704+6620
Authors: Nashed G.G.L. , El Hanafy Waleed
Published: September 2023

We apply quadratic f(R) = R + ϵR
2 field equations, where ϵ has a dimension [L2], to static spherical stellar model. We assume the interior configuration is determined by Krori-Barua ansatz and additionally the fluid is anisotropic. Using the astrophysical measurements of the pulsar PSR J0740+6620 as inferred by NICER and XMM observations, we determine ϵ ≈ ± 3 km2. We show that the model can provide a stable configuration of the pulsar PSR J0740+6620 in both geometrical and physical sectors. We show that the Krori-Barua ansatz within f(R) quadratic gravity provides semi-analytical relations between radial, pr
, and tangential, pt
, pressures and density ρ which can be expressed as pr
≈ vr

2 (ρ-ρ
1) and pr
≈ vt

2 (ρ-ρ
2), where vr
(vt
) is the sound speed in radial (tangential) direction, ρ
1 = ρs
(surface density) and ρ
2 are completely determined in terms of the model parameters. These relations are in agreement with the best-fit equations of state as obtained in the present study. We further put the upper limit on the compactness, C = 2GMRs

-1
c
-2, which satisfies the f(R) modified Buchdahl limit. Remarkably, the quadratic f(R) gravity with negative ϵ naturally restricts the maximum compactness to values lower than Buchdahl limit, unlike the GR or f(R) gravity with positive ϵ where the compactness can arbitrarily approach the black hole limit C → 1. The model predicts a core density a few times the saturation nuclear density ρ
nuc = 2.7 × 1014 g/cm3, and a surface density ρs
> ρnuc
. We provide the mass-radius diagram corresponding to the obtained boundary density which has been shown to be in agreement with other observations.
Optical anapole modes in hybrid metal–dielectric nanoantenna for near-field enhancement and optical sensing
Authors: Wang 王 Debao 德宝 , Lv 吕 Jingwei 靖薇 , Liu 刘 Wei 伟 , Ren 任 Yanru 艳茹 , Li 李 Wei 薇 , Xu 许 Xinchen 鑫辰 , Liu 刘 Chao 超 , Chu 朱 Paul K 剑豪
Published: September 2023

Metal–dielectric nanostructures in the optical anapole modes are essential for light–matter interactions due to the low material loss and high near-field enhancement. Herein, a hybrid metal–dielectric nanoantenna composed of six wedge-shaped gold (Au) nanoblocks as well as silica (SiO2) and silicon (Si) nanodiscs is designed and analyzed by the finite element method (FEM). The nanoantenna exhibits flexibility in excitation and manipulation of the anapole mode through the strong coupling between the metal and dielectrics, consequently improving the near-field enhancement at the gap. By systematically optimizing the structural parameters, the electric field enhancement factors at wavelengths corresponding to the anapole modes (AM1 and AM2) can be increased to 518 and 1482, respectively. Moreover, the nanoantenna delivers great performance in optical sensing such as a sensitivity of 550 nm/RIU. The results provide guidance and insights into enhancing the coupling between metals and dielectrics for applications such as surface-enhanced Raman scattering and optical sensing.
Effect of mono-/divalent metal ions on the conductivity characteristics of DNA solutions transferring through a microfluidic channel
Authors: Zhu 朱 Jie 洁 , Xue 薛 Jing 菁 , Zhao 赵 Wei 伟 , Zhang 张 Chen 琛 , Feng 冯 Xiaoqiang 晓强 , Wang 王 Kaige 凯歌
Published: September 2023

Interactions between deoxyribonucleic acid (DNA) and metal ions are vital for maintaining life functions, however, there are still unsolved questions about its mechanisms. It is of great practical significance to study these issues for medical chip design, drug development, health care, etc. In this investigation, the conductivity properties of λ-DNA solutions with mono-/divalent metal ions (Na+, K+, Mg2+, and Ca2+) are experimentally studied as they are electrically driven through a 5 μm microfluidic channel. Experimental data indicate that the conductivities of λ-DNA solutions with metal ions (M+/M2+) basically tend to reduce firstly and then increase as the voltage increases, of which the turning points varied with the metal ions. When the voltage surpasses turning points, the conductivity of λ-DNA-M+ solutions increases with the concentration of metal ions, while that of λ-DNA-M2+ solutions decrease. Moreover, the conductivity of λ-DNA-M2+ solutions is always smaller than that of λ-DNA-M+ solutions, and with high-concentration M2+, it is even smaller than that of the λ-DNA solution. The main reasons for the above findings could be attributed to the polarization of electrodes and different mechanisms of interactions between metal ions and λ-DNA molecules. This investigation is helpful for the precise manipulation of single DNA molecules in micro-/nanofluidic space and the design of new biomedical micro-/nanofluidic sensors.
Static-to-kinematic modeling and experimental validation of tendon-driven quasi continuum manipulators with nonconstant subsegment stiffness
Authors: Zheng 郑 Xian-Jie 先杰 , Ding 丁 Meng 萌 , Liu 刘 Liao-Xue 辽雪 , Wang 王 Lu 璐 , Guo 郭 Yu 毓
Published: September 2023

Continuum robots with high flexibility and compliance have the capability to operate in confined and cluttered environments. To enhance the load capacity while maintaining robot dexterity, we propose a novel non-constant subsegment stiffness structure for tendon-driven quasi continuum robots (TDQCRs) comprising rigid-flexible coupling subsegments. Aiming at real-time control applications, we present a novel static-to-kinematic modeling approach to gain a comprehensive understanding of the TDQCR model. The analytical subsegment-based kinematics for the multisection manipulator is derived based on screw theory and product of exponentials formula, and the static model considering gravity loading, actuation loading, and robot constitutive laws is established. Additionally, the effect of tension attenuation caused by routing channel friction is considered in the robot statics, resulting in improved model accuracy. The root-mean-square error between the outputs of the static model and the experimental system is less than 1.63% of the arm length (0.5 m). By employing the proposed static model, a mapping of bending angles between the configuration space and the subsegment space is established. Furthermore, motion control experiments are conducted on our TDQCR system, and the results demonstrate the effectiveness of the static-to-kinematic model.
Quintessence anisotropic stellar models in quadratic and Born–Infeld modified teleparallel Rastall gravity
Authors: Ditta Allah , Xia 夏 Tiecheng 铁成 , Mahmood Irfan , Mahmood Asif
Published: September 2023

This study aims to discuss anisotropic solutions that are spherically symmetric in the quintessence field, which describe compact stellar objects in the modified Rastall teleparallel theory of gravity. To achieve this goal, the Krori and Barua arrangement for spherically symmetric components of the line element is incorporated. We explore the field equations by selecting appropriate off-diagonal tetrad fields. Born–Infeld function of torsion

f
(
T
)
=
β

λ
T
+
1

−
1

and power law form h(T) = δTn
are used. The Born–Infeld gravity was the first modified teleparallel gravity to discuss inflation. We use the linear equation of state pr
= ξρ to separate the quintessence density. After obtaining the field equations, we investigate different physical parameters that demonstrate the stability and physical acceptability of the stellar models. We use observational data, such as the mass and radius of the compact star candidates PSRJ 1416-2230, Cen X-3, & 4U 1820-30, to ensure the physical plausibility of our findings.
Modelling and motion characteristics of a new multistage lead screw telescopic mechanism
Authors: Gao Xiaohui , Feng Zhipeng , Tong Saisai , Liu Yongguang
Published: September 2023

This paper presents a novel multistage electric telescopic mechanism. The mechanism is composed of multistage lead screw mechanism and multistage telescopic sleeve mechanism. It has the advantages of large stroke, large load and anti-sticking. Moreover, it has superior lateral bearing capacity and can be used in both transverse and longitudinal heavy load conditions. The force of the mechanism is analysed and the motion principle of the mechanism is expounded. Its mathematical model is established and its motion characteristics are studied. The speed, displacement and force data of the lead screw are analysed to verify its reliability and stability. The appropriate design parameters are obtained through the combination of experiment and simulation.
Modular design and simulation analysis of truss robot based on spatial bars structure
Authors: Wang Leilei , Gao Peng , Che Lei
Published: September 2023

For industrial applications, truss robots can perform mutipleoperations, such as transporting objects and handling tools independently, but face the challenges of inconvenient disassembly and non-recyclability. Therefore, a truss robot load-bearing module based on a spatial bar structure is designed, which consists of truss bars and connectors. Ansys Workbench is used for the static analysis of the truss robot beam. The results show that the maximum stress of the truss robot beam is 32.46 MPa and the maximum deformation is 1.1 mm under the load of 12,000 N. The maximum stress of the beam is significantly small than the yield limit of the material and the deformation is small, which meets the requirements of structural strength and load stability of the truss robot. Based on the mode analysis of the truss robot, the inherent vibration and frequency of the truss robot are extracted, providing a reference basis for the stability control of the truss robot. The modular truss robot has mutiple advantages, including the large span, high load capacity and assembly flexibility.
Finite element simulation study on cutting coal and rock by cutting head of roadheader
Authors: Liang Jianan , Tian Muqin , Huo Pengfei
Published: September 2023

In order to improve the cutting efficiency of the roadheader and address the challenge of monitoring the load of the cutting head and pick, a load simulation method was proposed using ABAQUS finite element software to simulate the cutting head at different cutting depths under various cutting conditions. According to the coal cutting test, a finite element simulation model was developed using Drucker-Prager as the constitutive model of coal to simulate the conical pick cutting of coal. The results of the finite element analysis were compared with the cutting test results, and the reliability of the former was confirmed. The study further involved establishing a model of cutting coal with different depths under various working conditions, and the torque waveform was obtained through finite element simulation. MATLAB was employed to program the theoretical formula, the theoretical waveforms of the force and torque of the cutting head were obtained. Additionally, the mean value of the cutting force of each pick in the finite element simulation results under different working conditions was statistically analyzed, and its distribution law was obtained. The results showed that the finite element simulation results were in good consistency with the theoretical calculation results, indicating that the simulation method was both reasonable and feasible for simulating the coal cutting process. Finite element simulation combined with theoretical calculation can be used in the stability control of cutting head dynamic load, and provide a basis for improving cutting efficiency.