bluuebunny/crossref_metadata_2025 huggingface dataset:
Rare-earth (Eu3+) substitution impact on the structural, morphological, magneto-dielectric, and electrochemical properties of Cd0.45Co0.55Fe2−y
Eu
y
O4 spinel nanoferrites
Authors: Afzal F , Alhadhrami A , Ibrahim Mohamed M , El-Bahy Zeinhom M , Rahman A U
Published: July 2024

A series of

C

d

0.45

C

o

0.55

F

e

2
−
y

E

u

y

O

4

(y = 0.0, 0.1, 0.2, 0.3) spinel nanoferrites (SNFs) were synthesized using a self-igniting process and employed as electrode materials for supercapacitor applications. The results demonstrated the formation of a single SNFs phase, as shown by the XRD data. The crystallite size lies between the range of 29.30–51.12 nm. The porosity percentage is within the range of 31.37%–32.99%. Rietveld refinement of XRD and Raman analysis revealed the pure spinel phase and no secondary phase was observed. The saturation magnetization and magnetic anisotropy were also decreased with the addition of Eu3+ in Cd–Co SNFs. The high coercive field was enhanced for Eu3+ doping as compared to pure Cd–Co SNFs. The dielectric constant was improved with the substitution of Eu3+ in Cd–Co SNFs. The dielectric tangent loss was reduced with the doping of Eu3+. The electrochemical performance of the Eu3+ doped Cd–Co SNFs achieved an impressive maximum specific capacitance at a lower scan rate. Based on these findings, the outstanding electrochemical performance of the Eu3+ doped Cd–Co SNFs suggests their potential as promising materials for high-frequency, magnetic ferrofluid, and supercapacitor electrodes.
A high-speed YOLO detection model for steel surface defects with the channel residual convolution and fusion-distribution
Authors: Huang Jianhang , Zhang Xinliang , Jia Lijie , Zhou Yitian
Published: July 2024

Accurately and efficiently detecting steel surface defects is a critical step in steel manufacturing. However, the compromise between the detection speed and accuracy remains a major challenge, especially for steel surface defects with large variations in the scale. To address the issue, an improved you only look once (YOLO) based detection model is proposed through the reinforcement of its backbone and neck. Firstly, for the reduction of the redundant parameters and also the improvement of the characterization ability of the model, an effective channel residual structure is adopted to construct a channel residual convolution module and channel residual cross stage partial module as components of the backbone network, respectively. They realize the extraction of both the shallow feature and multi-scale feature simultaneously under a small number of convolutional parameters. Secondly, in the neck of YOLO, a fusion-distribution strategy is employed, which extracts and fuses multi-scale feature maps from the backbone network to provide global information, and then distributes global information into local features of different branches through an inject attention mechanism, thus enhancing the feature gap between different branches. Then, a model called CRFD-YOLO is derived for the steel surface defect detection and localization for the situations where both speed and accuracy are demanding. Finally, extensive experimental validations are conducted to evaluate the performance of CRFD-YOLO. The validation results indicate that CRFD-YOLO achieves a satisfactory detection performance with a mean average precision of 81.3% on the NEU-DET and 71.1% on the GC10-DET. Additionally, CRFD-YOLO achieves a speed of 161 frames per second, giving a great potential in real-time detection and localization tasks.
Grand-potential phase field simulations of droplet growth and sedimentation in a two-phase ternary fluid
Authors: Verdier Werner , Cartalade Alain , Plapp Mathis
Published: July 2024

A methodology is built to model and simulate the dynamics of domain coarsening of a two-phase ternary liquid with an arbitrary phase diagram. High numerical performance is obtained through the use of the phase field-method for interface capturing, a lattice Boltzmann method numerical scheme for all the model equations, and a portable, parallel simulation code running on multiple GPUs. The model is benchmarked against an analytic solution for a ternary diffusion couple. It also reproduces the well-known power law for droplet coarsening during Ostwald ripening without fluid flow. Large-scale simulations with flow illustrate the effects of momentum transport and buoyancy, as well as droplet coalescence and sedimentation.
A novel relative-equilibrium graphical plot for rapid reversible tracer studies in dynamic PET imaging
Authors: Tian Zifeng , Zuo Yang , Xi Peng , Meng Xiangxi , Shao Wenrui , Yang Yidong , Ren Qiushi , Yu Jiangyuan , Xie Zhaoheng
Published: July 2024

Objective. This study aims to address the issue of long scan durations required by traditional graphical analysis methods, such as the Logan plot and its variant, the reversible equilibrium (RE) Logan plot, for dynamic PET imaging of tracer kinetics. Approach. We propose a relative RE Logan model that builds on the principles of the Logan plot and its variant to significantly reduce scan time without compromising the accuracy of tracer kinetics analysis. The model is supported by theoretical evidence and experimental validations, including two computer simulations and one clinical data analysis. Main results. The proposed model demonstrates a significant linear relationship between the variable x and the slope DVT
of the RE Logan plot, and the variable x′ and the slope

D

V
T
′

of the relative RE Logan plot. The Pearson correlation coefficients (r) of the linear fitting of the x′ to the x equal 0.9849 in the simulated data and 0.9912 in the clinical data. Similarly, the r values for the linear fitting of

D

V
T
′

to DVT
equal 0.9989 and 0.9988 in the simulated data, and 0.9954 in the clinical data. Significance. These results demonstrate the model’s capability to maintain strong linear relationships and produce parametric images comparable to the traditional RE Logan plot, but with the considerable advantage of shorter scan durations. This innovation holds significant potential for enhancing the efficiency and feasibility of PET imaging in clinical settings.
The effect of high-Z dopant on the ablation of carbon–hydrogen polymer target
Authors: Xiong Wei , Yang Xiaohu , Zhang Guobo , Chen Zehao , Cui Ye , Zeng Bo , Li Ze , Li Lingrui , Xu Bihao , Dong Yulong , Ma Yanyun
Published: July 2024

High-Z dopants such as chlorine, bromine and silicon in carbon–hydrogen polymer (CH) targets play a crucial role during the ablation of inertial confinement fusion (ICF). These dopants can serve as diagnostic tools in experiments and mitigate hot electron preheating, but they also influence the laser ablation. In this paper, the process of high-power laser ablating doped CH targets has been studied through radiation hydrodynamic simulations. Our findings reveal that the laser absorption rate in the doped targets increase as a result of the increasing electron-ion collision frequency. This leads to the increase of the electron, ion and radiation temperatures. Furthermore, high-Z dopants contribute to a decrease in the ablation pressure, which tends to a constant. Moreover, the saturation phenomenon of the mass ablation rate has been found. For the targets with low doping ratios (e.g. 6.25%–12.5%), the mass ablation rate increases until reaching the saturation at a doping ratio of 18.75%, after which it decreases. This indicates that an appropriate doping ratio can increase the laser absorption and ablation. The results are helpful to comprehensively understand the effects of high-Z dopant on all stages of ICF.
Understanding attosecond streaking
Authors: Ortmann Lisa , Landsman Alexandra
Published: July 2024

This tutorial provides an overview on the theory of attosecond streaking, a pump-probe scheme to extract timing information of ionization processes that has been widely used in the past decade. Emphasis is put on the origin of the Coulomb-laser-coupling (CLC) term, which is crucial in the interpretation of streaking delays. Having gained a proper understanding of how the CLC terms in various publications relate to each other, we will be able to analyze in which regime the streaking delay can be split into a measurement-induced CLC term and a ‘pure’ ionization delay and under which conditions this splitting may break down. Thus we address the long-standing question of the validity of the widely applied interpretation of the streaking delay as a sum of the CLC term and a ‘pure’ ionization delay.
Experimental investigation of dipole formation and modulation at Hf0.5Zr0.5O2/SiO2 interface
Authors: Gong Manru , Zhou Lixing , Wang Xiaolei , Dai Saifei , Cui Jialu , Dai Cong , Zhang Yamin , Feng Shiwei
Published: July 2024

HfO2-doped ferroelectric field-effect transistors have been extensively studied since the discovery of ferroelectricity in HfO2. A metal/ferroelectric/insulator/semiconductor structure is widely used in FeFETs. The dipole at the doped-HfO2/SiO2 interface is not well understood, though it plays an important role in the flat voltage shift and band alignment which strongly affects charge trapping. This study investigates the band alignment and dipole distribution at the

Hf

0.5

Zr

0.5

O

2

/SiO2 interface using x-ray photoelectron spectroscopy. The band bending of the

Hf

0.5

Zr

0.5

O

2

/SiO2/Si structure is found to vary with

Hf

0.5

Zr

0.5

O

2

layer thickness. The valence band offset (VBO) at the

Hf

0.5

Zr

0.5

O

2

/SiO2 interface decreases with increasing

Hf

0.5

Zr

0.5

O

2

thickness. It is confirmed that the dipole contributes to the dependence of band bending and VBO on

Hf

0.5

Zr

0.5

O

2

thickness. Dipole formation is caused by the charge neutral level mismatch between

Hf

0.5

Zr

0.5

O

2

and the SiO2/Si stack, which induces electron transfer and band bending. O2 post deposition annealing (PDA) can modulate the dipole distribution and generate a larger dipole at the

Hf

0.5

Zr

0.5

O

2

/SiO2 interface than that of the sample not subjected PDA.
Effect of calcination temperature on structural, optical, and morphological properties of RAlO3 (R = La, Sm) perovskite oxides
Authors: Vijayan Vinoth , R Murali
Published: July 2024

RAlO3 (R = La, Sm) have attracted the research community due to their interesting optoelectronic properties and viable applications. The solution combustion method allows for a faster process and lower calcination temperature than the traditional solid-state method and is an economical alternative to wet chemical synthesis for producing RAlO3. This work explores the thermal, structural, morphological, optical, and electrical properties of RAlO3 (R = La, Sm) synthesised by the solution combustion method using urea as fuel. Thermogravimetric analysis—differential thermal analysis (TGA-DTA) showed the crystallization temperatures of lanthanum aluminate (LaAlO3) and samarium aluminate (SmAlO3) at 864 and 887 °C, respectively. The x-ray diffraction (XRD) and Rietveld analysis revealed the structure of LaAlO3 as rhombohedral (R-3c) and SmAlO3 as orthorhombic (Pbnm). The LaAlO3 and SmAlO3 samples calcinated at 800 °C showed crystallite size (D) of 19.26 nm and 19.06 nm, respectively. The field emission scanning electron microscopy (FE-SEM) images show a highly porous and large sheet-like morphology with voids and cracks. High resolution transmission electron microscopy (HR-TEM) images and the selective area electron diffraction (SAED) pattern show crystalline nature and the indexed planes agreed with the XRD results. The LaAlO3 and SmAlO3 samples had specific surface areas of 16.374 and 12.953 m2 g−1, respectively. The TGA-DTA results were affirmed by Fourier transform infrared spectroscopy (FT-IR) results which showed only the presence of metal-oxide bonds for materials annealed at and above 800 °C. These results were further validated by the electron dispersive x-ray spectroscopy (EDX) and the x-ray photoelectron spectroscopy (XPS) showing no additional peaks. The band gap of 5.08 and 4.82 eV were calculated from ultraviolet-visible spectroscopy (UV–vis) for LaAlO3 and SmAlO3, respectively. The results imply that the solution combustion technique using urea as fuel is a viable route for synthesising RAlO3.
Structural and optical properties of green-synthesised tricobalt tetroxide nanoparticles
Authors: Mandal Biplab Kumar , Chauhan Pratap Singh , Das Rahul
Published: July 2024

In this study, we investigated the structural and optical properties of garlic extract-based green-synthesised tricobalt tetroxide nanoparticles. Transmission electron microscopy revealed a particle size range of 8–22 nm for the prepared powder sample. Powder x-ray diffraction data and Rietveld refinement results confirmed the spinel cubic crystal structure of the tricobalt tetroxide nanoparticles, with an average crystallite size of 11.23 nm. This crystal structure corresponds to the Fd3̅m space group and has an average lattice constant of 0.791 nm. The bond lengths of Co3+–O2− and Co2+–O2− are measured to be 0.188 nm and 0.190 nm, respectively. The FTIR data provided evidence of the presence of various functional bands, which helped qualitatively determine the purity of the sample. The UV–vis spectrum estimated two direct energy band gap values (3.7 eV and 2.2 eV) that may be useful for efficient interaction with a wide range of ray spectra to create more electron–hole pairs for various photo-responsive applications, such as dye degradation, solar cells, and optoelectronic components.
GaAs-on-insulator based vertical heterojunction tunnel FET: proposal and analysis for VLSI circuit applications
Authors: Mishra Varun , Singh Ashish Kumar , Nautiyal Rahul , Chauhan Akhilesh
Published: July 2024

This work analyses the Gallium Arsenide (GaAs)-on-insulator based vertical heterojunction tunnel FET with Gallium Antimonide (GaSb) as source material and GaAs as channel/drain material (GaSb/GaAs VTFET) to enhance the performance of the device and is compared with the Silicon-based VTFET. Silvaco Atlas TCAD tool is employed to perform numerical calculations. Tentative fabrication process flow of GaSb/GaAs VTFET is presented. GaSb is a low bandgap material that enhances the tunneling of charge carriers at source-channel heterojunction. GaSb/GaAs VTFET device outperforms Si-based VTFET in terms of electrical performance metrics such as ON-state current (ION), and ION/IOFF increases by a factor of 11 and 270 respectively; whereas OFF-state current (IOFF), subthreshold swing (SS), threshold voltage (VT) and drain-induced barrier lowering (DIBL) reduce by 95.98%, 39.36%, 17.14% and 29.17% respectively. Further, analog/RF and linearity/distortion performance analysis is carried out. GaSb/GaAs VTFET has improved analog/RF performances in terms of cut-off frequency (fT), gain-bandwidth product (GBP), transit time (τ), device efficiency (DE), transconductance frequency product (TFP) and suppressed distortions in compare to Si-based VTFET. Finally, GaSb/GaAs VTFET is evaluated for process variations and designing digital inverter and common source amplifier circuits. The Look-up-table (LUT) based Verilog-A model within the CADENCE tool has been employed to scrutinize the transient responses of inverter and common source amplifier circuits. Unity gain frequency and 3-dB bandwidth obtained for GaSb/GaAs VTFET amplifier are 15 GHz and 5.97 GHz. Therefore, this work presents GaSb/GaAs VTFET’s strong candidature for analog and digital VLSI circuit designing.
Quantum broadcasting of the generalized GHZ state: quantum noise analysis using quantum state tomography via IBMQ simulation
Authors: Mafi Yousef , Kookani Ali , Aghababa Hossein , Barati Masoud , Kolahdouz Mohammadreza
Published: July 2024

This study focuses on the challenges posed by quantum noise to communication protocols, with a particular emphasis on the vulnerabilities of current quantum broadcast protocols. The research employs the generalized GHZ state, known for its multipartite entangled cluster state with real-value coefficients, as a diagnostic tool to understand and address the impact of quantum noise on transmitted information. Implementing two novel controlled quantum broadcast schemes on the IBM Quantum (IBMQ) Experience platform, using the Qiskit library and the QASM simulator, the investigation evaluates the effects of four different types of quantum noise through Kraus operator models. A notable aspect of the study is the pioneering use of quantum state tomography for a comprehensive analysis of quantum noise effects, providing novel insights into the resilience of quantum communication protocols.
Experimental studies of H2/Ar plasma in a cylindrical inductive discharge with an expansion region
Authors: Li 李 Shi-Bo 世博 , Xing 邢 Si-Yu 思雨 , Gao 高 Fei 飞 , Wang 王 You-Nian 友年
Published: July 2024

The electrical parameters of H2/Ar plasma in a cylindrical inductive discharge with an expansion region are investigated by a Langmuir probe, where Ar fractions range from 0% to 100%. The influence of gas composition and pressure on electron density, the effective electron temperature and the electron energy probability functions (EEPFs) at different spatial positions are present. In driver region, with the introduction of a small amount of Ar at 0.3 Pa, there is a rapid increase in electron density accompanied by a decrease in the effective electron temperature. Additionally, the shape of the EEPF transitions from a three-temperature distribution to a bi-Maxwellian distribution due to an increase in electron–electron collision. However, this phenomenon resulting from the changes in gas composition vanishes at 5 Pa due to the prior depletion of energetic electrons caused by the increase in pressure during hydrogen discharge. The EEPFs for the total energy in expansion region is coincident to these in the driver region at 0.3 Pa, as do the patterns of electron density variation between these two regions for differing Ar fractions. At 5 Pa, as the discharge transitions from H2 to Ar, the EEPFs evolved from a bi-Maxwellian distribution with pronounced low energy electrons to a Maxwellian distribution in expansion region. This evolve may be attributed to a reduction in molecular vibrational excitation reactions of electrons during transport and the transition from localized electron dynamics in hydrogen discharge to non-localized electron dynamics in argon discharge. In order to validate the experimental results, we use the COMSOL simulation software to calculate electrical parameters under the same conditions. The evolution and spatial distribution of the electrical parameters of the simulation results agree well with the trend of the experimental results.
Study of leakage current degradation based on stacking faults expansion in irradiated SiC junction barrier Schottky diodes
Authors: Luo 罗 Maojiu 茂久 , Zhang 张 Yourun 有润 , Wang 王 Yucheng 煜丞 , Chen 陈 Hang 航 , Zhou 周 Rong 嵘 , Wang 王 Zhi 智 , Lu 陆 Chao 超 , Zhang 张 Bo 波
Published: July 2024

A comprehensive investigation was conducted to explore the degradation mechanism of leakage current in SiC junction barrier Schottky (JBS) diodes under heavy ion irradiation. We propose and verify that the generation of stacking faults (SFs) induced by the recombination of massive electron--hole pairs during irradiation is the cause of reverse leakage current degradation based on experiments results. The irradiation experiment was carried out based on Ta ions with high linear energy transfer (LET) of 90.5 MeV/(mg/cm2). It is observed that the leakage current of the diode undergoes the permanent increase during irradiation when biased at 20% of the rated reverse voltage. Micro-PL spectroscopy and PL micro-imaging were utilized to detect the presence of SFs in the irradiated SiC JBS diodes. We combined the degraded performance of irradiated samples with SFs introduced by heavy ion irradiation. Finally, three-dimensional (3D) TCAD simulation was employed to evaluate the excessive electron–hole pairs (EHPs) concentration excited by heavy ion irradiation. It was observed that the excessive hole concentration under irradiation exceeded significantly the threshold hole concentration necessary for the expansion of SFs in the substrate. The proposed mechanism suggests that the process and material characteristics of the silicon carbide should be considered in order to reinforcing against the single event effect of SiC power devices.
Image encryption algorithm based on multiple chaotic systems and improved Joseph block scrambling
Authors: Mou 牟 Dingkang 定康 , Dong 董 Yumin 玉民
Published: July 2024

With the rapid development of digital information technology, images are increasingly used in various fields. To ensure the security of image data, prevent unauthorized tampering and leakage, maintain personal privacy, and protect intellectual property rights, this study proposes an innovative color image encryption algorithm. Initially, the Mersenne Twister algorithm is utilized to generate high-quality pseudo-random numbers, establishing a robust basis for subsequent operations. Subsequently, two distinct chaotic systems, the autonomous non-Hamiltonian chaotic system and the tent-logistic-cosine chaotic mapping, are employed to produce chaotic random sequences. These chaotic sequences are used to control the encoding and decoding process of the DNA, effectively scrambling the image pixels. Furthermore, the complexity of the encryption process is enhanced through improved Joseph block scrambling. Thorough experimental verification, research, and analysis, the average value of the information entropy test data reaches as high as 7.999. Additionally, the average value of the number of pixels change rate (NPCR) test data is 99.6101%, which closely approaches the ideal value of 99.6094%. This algorithm not only guarantees image quality but also substantially raises the difficulty of decryption.
Dynamics of fundamental and double-pole breathers and solitons for a nonlinear Schrödinger equation with sextic operator under non-zero boundary conditions
Authors: Zhang 张 Luyao 路瑶 , Xie 解 Xiyang 西阳
Published: July 2024

We study the dynamics of fundamental and double-pole breathers and solitons for the focusing and defocusing nonlinear Schrödinger equation with the sextic operator under non-zero boundary conditions. Our analysis mainly focuses on the dynamical properties of simple- and double-pole solutions. Firstly, through verification, we find that solutions under non-zero boundary conditions can be transformed into solutions under zero boundary conditions, whether in simple-pole or double-pole cases. For the focusing case, in the investigation of simple-pole solutions, temporal periodic breather and the spatial-temporal periodic breather are obtained by modulating parameters. Additionally, in the case of multi-pole solitons, we analyze parallel-state solitons, bound-state solitons, and intersecting solitons, providing a brief analysis of their interactions. In the double-pole case, we observe that the two solitons undergo two interactions, resulting in a distinctive “triangle” crest. Furthermore, for the defocusing case, we briefly consider two situations of simple-pole solutions, obtaining one and two dark solitons.
A proposal to change the leap-second adjustments to coordinated universal time
Authors: Levine Judah
Published: July 2024

The definition of Coordinated Universal Time (UTC) in 1972 balanced the needs of the time and frequency community for a universal time scale that was traceable to the definition of frequency in the SI system of units with the needs of the astronomical community for a time scale that was closely linked to UT1, a time scale related to the rotation of Earth. The balance between these two considerations has changed very significantly since 1972, and there is widespread agreement that the method of relating UTC to UT1 should be changed by increasing the magnitude of the maximum tolerance between the two scales to more than the current limit of 0.9 s. We propose to realize this decision by means of an algorithmic adjustment process based on the variation in the length of the day over the previous centuries. We use these historical data to extrapolate the length of the day for a century into the future, and to compute a periodic rate adjustment to UTC based on this extrapolation. The adjustment process will not use time steps. The magnitude of the periodic rate adjustment will be re-considered every century, but the basic adjustment algorithm will not change. We suggest a maximum tolerance between UT1 and UTC that is large enough to absorb the irregular and unpredictable variations in the length of the day with respect to the long-term average increase in this value but plays no role in determining the parameters of the adjustment process that is proposed. We also propose that the adjustment be implemented at 12 UTC on 1 January or on another date that is close to a universal holiday in all time zones.
Scaffold design considerations for peripheral nerve regeneration
Authors: Yu Le , Bennett Carly Jane , Lin Chung-Hsun , Yan Su , Yang Jian
Published: July 2024

Peripheral nerve injury (PNI) represents a serious clinical and public health problem due to its high incurrence and poor spontaneous recovery. Compared to autograft, which is still the best current practice for long-gap peripheral nerve defects in clinics, the use of polymer-based biodegradable nerve guidance conduits (NGCs) has been gaining momentum as an alternative to guide the repair of severe PNI without the need of secondary surgery and donor nerve tissue. However, simple hollow cylindrical tubes can barely outperform autograft in terms of the regenerative efficiency especially in critical sized PNI. With the rapid development of tissue engineering technology and materials science, various functionalized NGCs have emerged to enhance nerve regeneration over the past decades. From the aspect of scaffold design considerations, with a specific focus on biodegradable polymers, this review aims to summarize the recent advances in NGCs by addressing the onerous demands of biomaterial selections, structural designs, and manufacturing techniques that contributes to the biocompatibility, degradation rate, mechanical properties, drug encapsulation and release efficiency, immunomodulation, angiogenesis, and the overall nerve regeneration potential of NGCs. In addition, several commercially available NGCs along with their regulation pathways and clinical applications are compared and discussed. Lastly, we discuss the current challenges and future directions attempting to provide inspiration for the future design of ideal NGCs that can completely cure long-gap peripheral nerve defects.
Automated object detection for muon tomography data analysis
Authors: Georgadze Anzori Sh.
Published: July 2024

In recent years, there have been ongoing efforts to improve screening technologies to improve security and prevent terrorist threats. The most widely used technologies for scanning shipping containers are gamma and X-ray radiography, which can be harmful to operators and the environment. Muon tomography screening systems are considered as a potential tool to enhance border security and prevent terrorist threats or smuggling, especially in the context of shipping container inspections. Muon tomography uses naturally occurring cosmic ray muons to create detailed images of the inside of objects, such as shipping containers, without the need for physical intervention. Various realistic smuggling scenarios were simulated using the GEANT4 toolkit. The implemented filtering algorithms successfully reduce background noise from the surrounding cargo, enabling the detection of concealed threats and contraband. With the tools provided by the ROOT data analysis package, prohibited items can be automatically detected and localized in a cargo container.
Propulsive performance of a heaving and pitching foil with large amplitudes in unsteady ground effect
Authors: Zhang Jian-Tao , Nakamura Takashi
Published: July 2024

To reveal the effect of ground on the force behavior, propulsion performance, and vortex dynamics of a flapping foil, we numerically study a flapping foil actuated by combined heaving and pitching motions with large amplitudes near a solid ground surface. The instantaneous forces in both streamwise and cross-stream directions undergo a sudden drop during upstroke in close ground effect. The time-averaged thrust is enhanced by the ground but varies non-monotonically with ground distance at high foil oscillating frequencies. Three force regimes are identified in lift production, giving rise to two equilibrium altitudes of zero lift, one stable and another unstable. Moreover, we propose a simple scaling law model by a path-length-based Strouhal number and ground effect for thrust and power performance of a large-amplitude flapping foil. The results of the model are consistent with numerical results and previous experimental studies. The vortex dynamics in the wake structure are largely affected by ground proximity; in particular, the formed vortex pairs and their orientations are sensitive to their initial relative positions. Different sources and mechanisms of satellite vortex formation are then discussed. The ground exerts little effect on the phase angles that optimize the propulsive efficiency. This study is expected to provide new insights into the development and maneuvering of flapping foil-based propulsive systems.
Effect of nickel and selenium co-doping on molybdenum disulfide structure and its electrochemical activity in polysulfide electrolyte
Authors: Batu Kasaye Bayisa , Shura Megersa Wodajo , Dibaba Solomon Tiruneh
Published: July 2024

The development of a low-cost, and highly effective platinum (Pt)-free counter electrode (CE) that is highly stable towards polysulfide electrolyte presents a substantial challenge. Trigonal Molybdenum disulfide (1T-MoS2) has shown good chemical stability toward polysulfide electrolytes. In this study, 1T-MoS2 was prepared by co-doping with nickel (Ni) and selenium (Se) into MoS2 through hydrothermal method and utilizing its reduction activity toward polysulfide electrolyte. According to electrochemical impedance spectroscopy (EIS) analysis, Ni-Se-MoS2 has a low charge transfer resistance and electron recombination lifetime. In addition, cyclic voltmeter (CV) analysis reveals a high absolute area indicating a high level of electrocatalytic activity for polysulfide reduction at the electrolyte/counter electrode (CE) interface. The XRD analysis shows that the phase shifting of 2H MoS2 to 1 T MoS2 and the intensity of the co-doped sample is lower than that of others. SEM analysis reveals a microsphere-flower-like morphology that increases specific surface area.
Numerical simulation and experimental investigation on friction stir welding of AZ31 magnesium alloy
Authors: Yan Zehua , Liu Xinna , Yang Sheng , Zhang Wei
Published: July 2024

Integrated numerical simulations and experimental investigations were employed to scrutinize the thermal, mechanical, and microstructural transformations of the AZ31 magnesium alloy during the friction stir welding (FSW) process. Especially, the primary focus was on the influence of process parameters such as rotational speed and welding speed on the temperature distribution, grain refinement, and mechanical properties of welded joints in alloys. By employing Deform-3D coupled with the integration of constitutive equations and dynamic recrystallization (DRX) models, the FSW process was investigated. The investigation revealed a significant increase in temperature when the tool’s shoulder made contact with the weld, resulting in the substantial accumulation of heat during FSW. Distinctions became apparent between the advancing side (AS) and the receding side (RS), with the AS exhibiting slightly elevated levels of temperature, equivalent stress, strain, and grain size. Specifically, adjustments in the rotational speed of the stirring tool and a reduction in welding speed resulted in larger grain sizes within the alloy. For example, when the rotational speed was set at 1200 rpm and the travel rate was 200 mm min−1, the initial grain size of the weld experienced a substantial decrease from 57.8 μm to 8.2 μm. Subsequent experimental verification, considering grain size and microhardness, was carried out to optimize FSW parameters for achieving the desired material properties. The accuracy of simulation results was validated through a meticulous comparison with experimental findings, underscoring the potential of numerical simulation in comprehending and predicting FSW processes.
Simulation of different structured gate-all-around FETs for 2 nm node
Authors: Totorica Nathan , Hu Wei , Li Feng
Published: July 2024

This paper compares different types of Gate All Around (GAA) FET structures using TCAD simulation, including Lateral Nanosheet, Lateral Nanowire, Vertical Nanosheet, and Vertical Nanowire. The increase in electrostatic control and reduced short channel effects are key benefits to adopting GAAFET structures to meet scaling requirements for next generation process nodes. To understand channel geometry impacts on performance, the channel effective width (Weff) is swept around the projected dimensions, including ratio of height and width parameters. The performance is evaluated using the key device metrics such as on-state current (Ion), off-state current (Ioff), and threshold voltage (Vt) for transfer characteristics, and drain-induced barrier lowering (DIBL), subthreshold slope (SS), and gate induced drain leakage (GIDL) for short-channel effects. It is observed that thinner channel geometries, as often seen implemented in Nanosheet structures, have major benefits across SCE and Ioff metrics compared to more symmetrically square shaped channels. Additionally, stacking channels as a means to increase Weff appears to be an attractive option for increasing performance without significant increase in SCEs observed. For bulk technology the ratio between height and width of a Nanosheet structure can be optimized to reduce parasitic channel influence, so that optimal Ion/Ioff ratio is achieved.
Negative order sobolev cubatures: preconditioners of partial differential equation learning tasks circumventing numerical stiffness
Authors: Suarez Cardona Juan-Esteban , Hofmann Phil-Alexander , Hecht Michael
Published: July 2024

We present a variational approach aimed at enhancing the training of physics-informed neural networks (PINNs) and more general surrogate models for learning partial differential equations (PDE). In particular, we extend our formerly introduced notion of Sobolev cubatures to negative orders, enabling the approximation of negative order Sobolev norms. We mathematically prove the effect of negative order Sobolev cubatures in improving the condition number of discrete PDE learning problems, providing balancing scalars that mitigate numerical stiffness issues caused by loss imbalances. Additionally, we consider polynomial surrogate models (PSMs), which maintain the flexibility of PINN formulations while preserving the convexity structure of the PDE operators. The combination of negative order Sobolev cubatures and PSMs delivers well-conditioned discrete optimization problems, solvable via an exponentially fast convergent gradient descent for λ-convex losses. Our theoretical contributions are supported by numerical experiments, addressing linear and non-linear, forward and inverse PDE problems. These experiments show that the Sobolev cubature-based PSMs emerge as the superior state-of-the-art PINN technique.
Improving nutrition science begins with asking better questions
Authors: Stern Dalia , Ibsen Daniel B , MacDonald Conor James , Chiu Yu-Han , Lajous Martin , Tobias Deirdre K
Published: July 2024

A priority of nutrition science is to identify dietary determinants of health and disease to inform effective public health policies, guidelines, and clinical interventions. Yet, conflicting findings in synthesizing evidence from randomized trials and observational studies have contributed to confusion and uncertainty. Often, heterogeneity can be explained by the fact that seemingly similar bodies of evidence are asking very different questions. Improving the alignment within and between research domains begins with investigators clearly defining their diet and disease questions; however, nutritional exposures are complex and often require a greater degree of specificity. First, dietary data are compositional, meaning a change in a food may imply a compensatory change of other foods. Second, dietary data are multidimensional; that is, the primary components (ie, foods) comprise subcomponents (eg, nutrients), and subcomponents can be present in multiple primary components. Third, because diet is a lifelong exposure, the composition of a study population’s background diet has implications for the interpretation of the exposure and the transportability of effect estimates. Collectively clarifying these key aspects of inherently complex dietary exposures when conducting research will facilitate appropriate evidence synthesis, improve certainty of evidence, and improve the ability of these efforts to inform policy and decision-making.
Effects of moderate/vigorous activity on 3-year body composition changes in postmenopausal women: a target trial emulation
Authors: Li Jiarui , Bea Jennifer W , LaMonte Michael , Jiang Luohua , Reding Kerryn , Garcia Lorena , Manson Jo Ann E , Follis Shawna , Odegaard Andrew O
Published: July 2024

Postmenopausal women experience significant changes in body composition, particularly abdominal adipose tissue (AAT) deposition patterns, which influence cardiometabolic risk. Physical activity has demonstrable effects on body composition and overall health; however, there is little evidence for how physical activity influences AAT patterns and body composition in postmenopausal women. We emulated a target trial of physical activity interventions, including the 2018 Physical Activity Guidelines for Americans recommendations (≥150 minutes/week), on 3-year changes in AAT and body composition. We analyzed data from 4451 postmenopausal women aged 50-79 years in the Women’s Health Initiative (WHI) with repeated whole body Dual X-Ray Absorptiometry (DXA) scans with derived abdominal visceral (VAT) and subcutaneous adipose tissue (SAT). The mean AAT and body composition measures were estimated with the parametric-g formula. Over 3 years, interventions of increasing minutes of moderate activity would result in dose-dependent reductions in AAT, overall body fat and increases in lean soft tissue, with the greatest estimated benefit at the 2018 physical activity guideline recommendations. Compared to no intervention, if all participants had adhered to ≥150 mins/week of moderate physical activity, they would have 16.8 cm2 lower VAT (95% CI: −23.1, −10.4), 26.8 cm2 lower SAT (95% CI: −36.3, −17.3), 1.3% lower total body fat (95% CI: −1.8, −0.7), 1.2% higher total lean soft tissue (95% CI: 0.7-1.8), and 2.6 kg lower bodyweight (95% CI, −3.6, −1.5). We saw similar patterns in vigorous-intensity activity interventions. These results suggest that postmenopausal women who adhere to physical activity guideline recommendations would experience beneficial body composition changes over 3 years.
Reusable tutorials for using cloud-based computing environments for the analysis of bacterial gene expression data from bulk RNA sequencing
Authors: Allers Steven , O’Connell Kyle A , Carlson Thad , Belardo David , King Benjamin L
Published: July 2024

This manuscript describes the development of a resource module that is part of a learning platform named “NIGMS Sandbox for Cloud-based Learning” https://github.com/NIGMS/NIGMS-Sandbox. The overall genesis of the Sandbox is described in the editorial NIGMS Sandbox at the beginning of this Supplement. This module delivers learning materials on RNA sequencing (RNAseq) data analysis in an interactive format that uses appropriate cloud resources for data access and analyses. Biomedical research is increasingly data-driven, and dependent upon data management and analysis methods that facilitate rigorous, robust, and reproducible research. Cloud-based computing resources provide opportunities to broaden the application of bioinformatics and data science in research. Two obstacles for researchers, particularly those at small institutions, are: (i) access to bioinformatics analysis environments tailored to their research; and (ii) training in how to use Cloud-based computing resources. We developed five reusable tutorials for bulk RNAseq data analysis to address these obstacles. Using Jupyter notebooks run on the Google Cloud Platform, the tutorials guide the user through a workflow featuring an RNAseq dataset from a study of prophage altered drug resistance in Mycobacterium chelonae. The first tutorial uses a subset of the data so users can learn analysis steps rapidly, and the second uses the entire dataset. Next, a tutorial demonstrates how to analyze the read count data to generate lists of differentially expressed genes using R/DESeq2. Additional tutorials generate read counts using the Snakemake workflow manager and Nextflow with Google Batch. All tutorials are open-source and can be used as templates for other analysis.
loco-pipe: an automated pipeline for population genomics with low-coverage whole-genome sequencing
Authors: Zhou Zehua T , Owens Gregory L , Larson Wesley A , Lou Runyang Nicolas , Sudmant Peter H
Published: July 2024

We developed loco-pipe, a Snakemake pipeline that seamlessly streamlines a set of essential population genomic analyses for low-coverage whole genome sequencing (lcWGS) data. loco-pipe is highly automated, easily customizable, massively parallelized, and thus is a valuable tool for both new and experienced users of lcWGS.

Availability and implementation

loco-pipe is published under the GPLv3. It is freely available on GitHub (github.com/sudmantlab/loco-pipe) and archived on Zenodo (doi.org/10.5281/zenodo.10425920).
isolateR: an R package for generating microbial libraries from Sanger sequencing data
Authors: Daisley Brendan , Vancuren Sarah J , Brettingham Dylan J L , Wilde Jacob , Renwick Simone , Macpherson Christine V , Good David A , Botschner Alexander J , Yen Sandi , Hill Janet E , Sorbara Matthew T , Allen-Vercoe Emma
Published: July 2024

Motivation

Sanger sequencing of taxonomic marker genes (e.g. 16S/18S/ITS/rpoB/cpn60) represents the leading method for identifying a wide range of microorganisms including bacteria, archaea, and fungi. However, the manual processing of sequence data and limitations associated with conventional BLAST searches impede the efficient generation of strain libraries essential for cataloging microbial diversity and discovering novel species.

Results

isolateR addresses these challenges by implementing a standardized and scalable three-step pipeline that includes: (1) automated batch processing of Sanger sequence files, (2) taxonomic classification via global alignment to type strain databases in accordance with the latest international nomenclature standards, and (3) straightforward creation of strain libraries and handling of clonal isolates, with the ability to set customizable sequence dereplication thresholds and combine data from multiple sequencing runs into a single library. The tool’s user-friendly design also features interactive HTML outputs that simplify data exploration and analysis. Additionally, in silico benchmarking done on two comprehensive human gut genome catalogues (IMGG and Hadza hunter-gather populations) showcase the proficiency of isolateR in uncovering and cataloging the nuanced spectrum of microbial diversity, advocating for a more targeted and granular exploration within individual hosts to achieve the highest strain-level resolution possible when generating culture collections.

Availability and implementation

isolateR is available at: https://github.com/bdaisley/isolateR.
Optimal refinement of strata to balance covariates
Authors: Brumberg Katherine , Small Dylan S , Rosenbaum Paul R
Published: July 2024

What is the best way to split one stratum into two to maximally reduce the within-stratum imbalance in many covariates? We formulate this as an integer program and approximate the solution by randomized rounding of a linear program. A linear program may assign a fraction of a person to each refined stratum. Randomized rounding views fractional people as probabilities, assigning intact people to strata using biased coins. Randomized rounding is a well-studied theoretical technique for approximating the optimal solution of certain insoluble integer programs. When the number of people in a stratum is large relative to the number of covariates, we prove the following new results: (i) randomized rounding to split a stratum does very little randomizing, so it closely resembles the linear programming relaxation without splitting intact people; (ii) the linear relaxation and the randomly rounded solution place lower and upper bounds on the unattainable integer programming solution; and because of (i), these bounds are often close, thereby ratifying the usable randomly rounded solution. We illustrate using an observational study that balanced many covariates by forming matched pairs composed of 2016 patients selected from 5735 using a propensity score. Instead, we form 5 propensity score strata and refine them into 10 strata, obtaining excellent covariate balance while retaining all patients. An R package optrefine at CRAN implements the method. Supplementary materials are available online.
A gain-of-function variant in SREBF1 causes generalized skin hyperpigmentation with congenital cataracts
Authors: Wang Huijun , Wu Yuan , Bassetti Jennifer A , Wang Zhaoyang , Oza Vikash S , Rangu Sneha A , McGivern Bobbi , Peng Sha , Liang Lina , Huang Shimiao , Gong Zhuoqing , Xu Zigang , Lin Zhimiao
Published: July 2024

Background

Lipid metabolism has essential roles in skin barrier formation and the regulation of skin inflammation. Lipid homeostasis regulates skin melanogenesis, although the underlying mechanism remains largely unknown. Sterol regulatory element binding protein 1 (SREBP-1) is a key transcription factor essential for cellular lipid metabolism. Loss-of-function variants in SREBF1 are responsible for autosomal-dominant ichthyosis follicularis, alopecia and photophobia syndrome, emphasizing the significance of lipid homeostasis in skin keratinization.

Objectives

To identify the genetic basis of a new entity featuring diffuse skin hyperpigmentation with congenital cataracts, and to unravel the underlying mechanism for the pathogenesis of the SREBF1 variant.

Methods

Whole-exome sequencing was performed to identify underlying genetic variants. Quantitative polymerase chain reaction, Western blot and immunofluorescence staining were used to assess the expression and the subcellular localization of the SREBF1 variant. The transcriptional activity of mutant SREBP-1 was determined by a luciferase reporter assay. A transgenic zebrafish model was constructed.

Results

Two unrelated patients presented with generalized skin hyperpigmentation with skin xerosis, congenital cataracts and extracutaneous symptoms. We identified a de novo nonsense variant c.1289C>A (p.Ser430*) in SREBF1 in both patients. The variant encoded a truncated protein that showed preferential nucleus localization, in contrast to wild-type SREBP-1 which – in sterol-sufficient conditions – is mainly localized in the cytoplasm. The luciferase reporter assay revealed that the p.Ser430* mutant exhibited enhanced transcriptional activity. Cultured patient primary melanocytes showed increased melanin synthesis vs. those from healthy controls. At 35 days postfertilization, the p.Ser430* transgenic zebrafish model exhibited more black spots, along with upregulated expression of melanogenic genes.

Conclusions

We demonstrated that a gain-of-function variant of SREBF1 causes a previously undescribed disorder characterized by generalized skin hyperpigmentation and congenital cataracts. Our study reveals the involvement of SREBP-1 in melanogenesis and lens development, and paves the way for the development of novel therapeutic targets for skin dyspigmentation or cataracts.