bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulating temperature and tautomeric effects for vibrationally resolved XPS of biomolecules: Combining time-dependent and time-independent approaches to fingerprint carbonyl groups
Authors: Wei Minrui , Zuo Junxiang , Tian Guangjun , Hua Weijie
Published: September 2024

Carbonyl groups (C=O) play crucial roles in the photophysics and photochemistry of biological systems. O1s x-ray photoelectron spectroscopy allows for targeted investigation of the C=O group, and the coupling between C=O vibration and O1s ionization is reflected in the fine structures. To elucidate its characteristic vibronic features, systematic Franck–Condon simulations were conducted for six common biomolecules, including three purines (xanthine, caffeine, and hypoxanthine) and three pyrimidines (thymine, 5F-uracil, and uracil). The complexity of simulation for these biomolecules lies in accounting for temperature effects and potential tautomeric variations. We combined the time-dependent and time-independent methods to efficiently account for the temperature effects and to provide explicit assignments, respectively. For hypoxanthine, the tautomeric effect was considered by incorporating the Boltzmann population ratios of two tautomers. The simulations demonstrated good agreement with experimental spectra, enabling differentiation of two types of carbonyl oxygens with subtle local structural differences, positioned between two nitrogens (O1) or between one carbon and one nitrogen (O2). The analysis provided insights into the coupling between C=O vibration and O1s ionization, consistently showing an elongation of the C=O bond length (by 0.08–0.09 Å) upon O1s ionization.
Experimental investigation on the tribo-mechanical behavior of PMMA reinforced by solid lubricant filler for dental implant applications
Authors: Abdo Mohamed S. , Shar Muhammad A. , Fouly Ahmed , Dar Mushtaq A. , Abdo Hany S.
Published: September 2024

This study investigates the enhancement of mechanical and tribological behavior in polymethyl methacrylate (PMMA) composites reinforced with graphene oxide (GO) as a solid lubricant filler for advanced biomedical applications, particularly dental implants. PMMA/GO composites were prepared with varying weight percentages of GO (0, 0.2, 0.5, 0.7, and 1 wt. %) to assess their impact on material performance. A noteworthy improvement in both tensile strength and Young’s modulus was detected, reaching up to 141% and 10.6%, respectively, at optimized GO loadings of 1%. Microstructural analysis utilizing scanning electron microscopy for the worn surface revealed enhanced dispersion and interfacial adhesion between GO and the PMMA matrix, reinforcing mechanical coherence. Tribological properties also demonstrated enhancement, with PMMA composites containing 1 wt. % GO exhibiting optimal mechanical and tribological characteristics compared to lower weight fractions. Moreover, microscopic examination revealed a shift in the wear mechanism of the PMMA-GO composite, which was attributed to the lower friction coefficient obtained by GO integration.
Multi-scale analysis of harmonic resonance in cylindrical bubbles under acoustic excitation
Authors: Yu Jiaxin , Luo Jinxin , Zhang Xiangqing , Zhang Yuning , Zhang Yuning
Published: September 2024

In this paper, the dimensionless oscillation equation of a cylindrical bubble is analyzed using the multi-scale method, Lyapunov stability theory, and the Routh–Hurwitz stability criterion. The corresponding second-order analytical solution and stability criterion are obtained. By examining the cases of second-order super-harmonic resonance and 1/2-order sub-harmonic resonance, the harmonic resonance characteristics of cylindrical bubbles and the influencing factors are revealed. The conclusions are summarized as follows: (1) Super-harmonic resonance can exhibit up to three solutions, along with unstable phenomena such as jump and hysteresis. Sub-harmonic resonance, however, shows at most two solutions simultaneously, without jump or hysteresis phenomena. (2) As the acoustic excitation amplitude increases, both the response amplitude and the unstable zone significantly enlarge. An increase in nonlinear coefficients can reduce the response amplitude and increase instability. (3) When the acoustic excitation amplitude reaches a certain threshold, the oscillation mode of the bubble shifts from periodic to chaotic. Under the same initial conditions, the chaos threshold for sub-harmonic resonance is higher than that for super-harmonic resonance.
Statistical study and parallelization of multiplexed single-electron sources
Authors: Norimoto S. , See P. , Schoinas N. , Rungger I. , Boykin T. O. , Stewart M. D. , Griffiths J. P. , Chen C. , Ritchie D. A. , Kataoka M.
Published: September 2024

Increasing the electric current from a single-electron source is a main challenge in an effort to establish the standard of the ampere defined by the fixed value of the elementary charge e and the operation frequency f. While the current scales with the frequency, due to an operation frequency limit for maintaining accurate single-electron transfer, parallelization of single-electron sources is expected to be a more practical solution to increase the generated electric current I=Nef, where N is the number of parallelized devices. One way to parallelize single-electron sources without increasing the complexity in device operation is to use a common gate. Such a scheme will require each device to have the same operation parameters for single-electron transfer. In order to investigate this possibility, we study the statistics for operation gate voltages using single-electron sources embedded in a multiplexer circuit. The multiplexer circuit allows us to measure 64 single-electron sources individually in a single cooldown. We also demonstrate the parallelization of three single-electron sources and observe the generated current enhanced by a factor of three.
Two-level system loss: Significant not only at millikelvin
Authors: Shan W. , Ezaki S.
Published: September 2024

Tow-level system (TLS) loss in amorphous dielectric materials has been intensively studied at millikelvin temperatures due to its impact on superconducting qubit devices and incoherent detectors. However, the significance of TLS loss in superconducting transmission lines at liquid helium temperatures remains unclear. This study investigates TLS loss in amorphous SiO2 at liquid helium temperatures (about 4 K) within a frequency range of 130–170 GHz, using niobium microstrip and coplanar waveguide resonators. Our results demonstrate notable power and temperature dependence of dielectric loss, with the dielectric loss and quasiparticle loss exchanging dominance at around 4 K. These findings are consistent with TLS models and provide crucial insight for the design of superconducting devices operating at liquid helium temperatures.
Electrolytes in conducting nanopores: Revisiting constant charge and constant potential simulations
Authors: Reinauer Alexander , Kondrat Svyatoslav , Holm Christian
Published: September 2024

Simulating electrolyte–electrode systems poses challenges due to the need to account for the electrode’s response to ion movements in order to maintain a constant electrode potential, which slows down the simulations. To circumvent this, computationally more efficient constant charge (CC) simulations are sometimes employed. However, the accuracy of CC simulations in capturing the behavior of electrolyte–electrode systems remains unclear, especially for microporous electrodes. Herein, we consider electrolyte-filled slit nanopores and systematically analyze the in-pore ion structure and diffusivity using CC and constant potential simulations. Our results indicate that CC simulations provide comparable pore occupancies at high bulk ion densities and for highly charged pores, but they fail to accurately describe the ion structure and dynamics, particularly in quasi-2D (single-layer) pores and at low ion densities. We attribute these results to the superionic state emerging in conducting nanoconfinement and its interplay with excluded volume interactions.
The significance of fuzzy boundaries of the barrier regions in single-molecule measurements of failed barrier crossing attempts
Authors: Berezhkovskii Alexander M. , Makarov Dmitrii E.
Published: September 2024

A recent ground-breaking experimental study [Lyons et al., Phys. Rev. X 14(1), 011017 (2024)] reports on measuring the temporal duration and the spatial extent of failed attempts to cross an activation barrier (i.e., “loops”) for a folding transition in a single molecule and for a Brownian particle trapped within a bistable potential. Within the model of diffusive dynamics, however, both of these quantities are, on average, exactly zero because of the recrossings of the barrier region boundary. That is, an observer endowed with infinite spatial and temporal resolution would find that finite loops do not exist (or, more precisely, form a set of measure zero). Here we develop a description of the experiment that takes the “fuzziness” of the boundaries caused by finite experimental resolution into account and show how the experimental uncertainty of localizing the point, in time and space, where the barrier is crossed leads to observable distributions of loop times and sizes. Although these distributions generally depend on the experimental resolution, this dependence, in certain cases, may amount to a simple resolution-dependent factor and, therefore, the experiments do probe inherent properties of barrier crossing dynamics.
In situ construction of sequential nanoreactor with built-in catalyst as self-supporting cathode for lithium–sulfur batteries
Authors: Wang Yu , Yang Yingqiang , Guo Pengbo , Chen Yi , Chen Yong , Cheng Yong , Xiao Jianrong , Li Xinyu
Published: September 2024

Architecture design and optimization are essential in improving the performance of lithium–sulfur batteries. Herein, an all-in-one sequential architecture of CoSe catalysts confined in MOF-derived nanoreactors (NRs) interfacially welded on carbon cloth (CC) is constructed using an in situ strategy (abbreviated: S@CoSe-NRs/CC). NRs with built-in CoSe (CoSe-NRs) have special microenvironments and domain-limited catalysis for efficient adsorption, catalysis, and deposition. The weld interface between the CoSe-NRs and the CC forms a continuous and robust all-in-one conductive network. Both experiments and theoretical calculations demonstrate that the S@CoSe-NRs/CC offers stable interconnectivity and efficient space utilization for high sulfur loads and rapid ion transport supply, providing a high initial discharge capacity of 1320 mA h g−1 at 0.1 C with a capacity decay rate as low as 0.003% per turn after 1000 cycles. This study offers unique insights and revelations for realizing the rational design of high-performance energy storage devices.
Light narrowing over broad temperature range with paraffin-coated vapor cells
Authors: Chen Shuyuan , Jin Xingqing , Xiang Wentian , Xiao Wei , Du Changping , Peng Xiang , Guo Hong
Published: September 2024

This study reports light narrowing in paraffin-coated vapor cells from room temperature 27 to 59 °C, where spin-exchange relaxation is suppressed. By means of a coating lock and eliminating the reservoir effect, an ultra-narrow magnetic resonance linewidth of 0.36 Hz and an atomic coherence lifetime of T2=0.9 s are achieved. In cells free of buffer gas, the narrow linewidth over this broad temperature range is a result of enhanced spin polarization, which is facilitated by the effective suppression of radiation trapping benefiting from the stability of the vapor density. Using such cells in atomic magnetometers, the photon shot noise limit is estimated as 0.2 fT/Hz1/2 and the spin-projection noise limit is estimated as 1.1 fT/Hz1/2. Also, a magnetometer system with the stable coated cell is identified, which demonstrates the potential for achieving relatively stable magnetometer sensitivity without precisely controlling the cell temperature. The long coherence lifetime and the broad operating temperature range expand the potential applications of quantum memory and other quantum sensors such as atomic clocks.
Iron: Life’s primeval transition metal
Authors: Johnson Jena E. , Present Theodore M. , Valentine Joan Selverstone
Published: September 2024

Modern life requires many different metal ions, which enable diverse biochemical functions. It is commonly assumed that metal ions’ environmental availabilities controlled the evolution of early life. We argue that evolution can only explore the chemistry that life encounters, and fortuitous chemical interactions between metal ions and biological compounds can only be selected for if they first occur sufficiently frequently. We calculated maximal transition metal ion concentrations in the ancient ocean, determining that the amounts of biologically important transition metal ions were orders of magnitude lower than ferrous iron. Under such conditions, primitive bioligands would predominantly interact with Fe(II). While interactions with other metals in certain environments may have provided evolutionary opportunities, the biochemical capacities of Fe(II), Fe–S clusters, or the plentiful magnesium and calcium could have satisfied all functions needed by early life. Primitive organisms could have used Fe(II) exclusively for their transition metal ion requirements.
Worldvolume fermions as baryons in holographic quantum chromodynamics with instantons
Authors: Li Si-wen , Li Hao-qian , Zhang Yi-peng
Published: September 2024

In this study, we investigated worldvolume fermions on the flavor brane in the D0–D4/D8 model, which is holographically equivalent to four-dimensional quantum chromodynamics with instantons or equivalently with a theta angle. The action involving the worldvolume fermions was obtained by the T-duality rules in string theory, and we accordingly derived their effective five-dimensional and canonical four-dimensional forms by using the systematic dimensional reduction and decomposition of the spinor. Subsequently, we used the AdS/CFT dictionary to evaluate the two-point correlation function as the spectral function for the worldvolume fermions and interpreted the fermions as baryons by analyzing their quantum number with the baryon vertex in holography. In this sense, the interacted action involving the worldvolume fermions and gauge field on the flavor brane was finally derived in holography, which describes the various interactions of mesons and baryons with instantons in the large-N limit. Therefore, this study provides a holographic picture to describe baryons and their interactions based on string theory, particularly in the presence of instantons or a theta angle.
Effective spin dynamics of spin-orbit coupled matter-wave solitons in optical lattices
Authors: Dey Kajal Krishna , Sekh Golam Ali
Published: September 2024

We consider matter–wave solitons in spin–orbit coupled Bose–Einstein condensates embedded in an optical lattice and study the dynamics of the soliton within the framework of Gross–Pitaevskii equations. We express spin components of the soliton pair in terms of nonlinear Bloch equations and investigate the effective spin dynamics. It is seen that the effective magnetic field that appears in the Bloch equation is affected by optical lattices, and thus the optical lattice influences the precessional frequency of the spin components. We make use of numerical approaches to investigate the dynamical behavior of density profiles and center-of-mass of the soliton pair in the presence of the optical lattice. It is shown that the spin density is periodically varying due to flipping of spinors between the two states. The amplitude of spin-flipping oscillation increases with lattice strength. We find that the system can also exhibit interesting nonlinear behavior for chosen values of parameters. We present a fixed point analysis to study the effects of optical lattices on the nonlinear dynamics of the spin components. It is seen that the optical lattice can act as a control parameter to change the dynamical behavior of the spin components from periodic to chaotic.
Dependence of ELM instability on separatrix density in EAST long-pulse H-mode plasmas
Authors: Wang Y.F. , Jia G.Z. , Xu G.S. , Chen R. , Chen L. , Yan N. , Wang L. , Zang Q. , Zhang T. , Duan Y.M. , Zhou T.F. , Jin Y.F. , Wang M.R. , Liu H.Q. , Gao W. , Yu Y.W. , Hu G.H. , Yang Q.Q. , Li K.D. , Lin X. , Ye Y. , Liu Z.Y. , Wang H.Q. , Huang J. , Gong X.Z. ,   EAST Teams
Published: September 2024

The transition from small edge-localized modes (ELMs) to large ELMs has been repetitively observed in minute-scale long-pulse high-confinement mode (H-mode) discharges during the 2017 EAST campaign. The appearance of large ELMs is found to be strongly correlated with the decrease in separatrix density due to the gradual decrease in fuel recycling during long-pulse H-mode operations (LPHOs). By the numerical scanning of separatrix density with a fixed temperature profile, it has been found that the dependence of ELM instability on separatrix density is related to the competition between the ion diamagnetic stabilizing effect and destabilizing effect of pressure gradient and current density in the pedestal region. This sheds light on a comprehensive understanding of the different roles of separatrix density in ELM instability observed during EAST experiments. With a high separatrix density, the ideal ballooning mode can be destabilized near the separatrix, which is thought to help achieve small ELMs in EAST LPHOs. During the 2021 EAST campaign, an experiment of large ELM control was performed through actively changing fuel recycling by moving the strike point location on the lower tungsten divertor target plate. It has been demonstrated that the mitigation of large ELMs is strongly correlated with the significant increase in separatrix density, which is thought to be attributed to a higher ionization source in the scrape-off layer (SOL) region by SOLPS-ITER simulation. The high ionization source in the SOL region is believed to provide a strong fueling effect near the separatrix and thus raise the local density, which is considered an important reason for triggering ballooning instabilities near the separatrix and achieving small ELMs.
Deep Reinforcement Learning-based Collaborative Multi-UAV Coverage Path Planning
Authors: Zhang Boquan , Jing Tian , Lin Xiang , Cui Yanru , Zhu Yifan , Zhu Zhi
Published: September 2024

The coverage path planning problem has gained significant attention in research due to its wide applicability and practical value in various fields such as logistics and distribution, smart homes, and unmanned vehicles. This paper focuses on studying the coverage path planning problem under multi-UAV collaboration to maximize the coverage of the mission area within a given time. To address this problem, we propose a multi-objective optimization model and reformulate it with the framework of Decentralized Partially Observable Markov Decision Process (Dec-POMDP). We then employ a multi-agent deep reinforcement learning (MADRL) method to solve the problem. Specifically, we introduce the ε—Multi-Agent Twin Delayed Deep Deterministic Policy Gradient (ε—MADT3), which incorporates an exploration coefficient based on MATD3. This coefficient gradually decays with the number of iterations, allowing for a balance between exploration and exploitation. Numerous simulation results demonstrate that ε—MADT3 outperforms the baseline algorithm in terms of coverage rate and number of collisions.
Research on microstructure evolution of laser surface quenching of ductile cast iron
Authors: Wang Huizhen , Zhai Yuewen , Zhou Leyu , Fan Zhenyu , Zhang Zibo , Zhan Yuheng
Published: September 2024

Ductile cast iron is widely used in the manufacturing of components and dies due to its excellent performance and low cost. Laser surface quenching can further improve its performance and extend its service life. This article uses scanning electron microscopy, electron backscattered scattering detection and microhardness tester to systematically analyse the microstructure evolution of the melted zone, hardened zone, and matrix of ductile cast iron with laser surface quenching. The hardening zone can be divided into two layers: one layer contains a large amount of martensite, graphite, and bits of residual austenite, and the other layer contains a composite structure of graphite, ferrite, layered martensite+austenite+Fe3C. On the basis of microstructure research, the determination and optimization methods of the depth of the laser surface hardening zone and the process are formed, providing a basis for the selection and optimization of the laser surface hardening process for ductile cast iron.
Waste to energy-study on the optimal types and dosage of additives for coal wastewater slurry
Authors: Li Dedi , Feng Biao , Liu Minrui , Luo Yuanlin , Wu Yuechao , Xu Junyang , Zhao Jun
Published: September 2024

As a clean and efficient fuel derived from coal, coal water slurry can be produced by using industrial wastewater, promoting resource recirculation and environmental preservation. To maintain fluidity and stability during industrial applications of coal wastewater slurry, stabilizers play a crucial role. To promote the energy utilization of industrial wastewater, this article conducted a comparative study on different stabilizers for coal wastewater slurry. The results are as follows: (a) Compared with other stabilizers, xanthan gum makes the water separation rate of the coal wastewater slurry the lowest, and the slurry still maintained good stability after standing for 1 week and 1 month; (b) If the coal wastewater slurry requires a short storage time, the slurry properties with a blending ratio of 0.05% of xanthan gum will be the best; if the coal wastewater slurry requires a longer storage time, it can be made with a blending ratio of 0.10% of xanthan gum. The conclusion presented in this paper offers valuable insights for selecting stabilizers during the preparation of coal wastewater slurry.
Enhanced coalbed methane recovery by microwave-induced thermal fracture
Authors: Wu Song , Li Shen , Yuan Shuxia , Guo Bintao , Niu Quansen
Published: September 2024

The investigation on microwave-induced permeabilization and response of coal under microwave heating is of great significance for the industrial application of microwave heating technology instead of traditional heating in coalbed methane mining. Santanghu coal is used as a sample to measure the permeability and porosity of coal samples before and after microwave heating. The fracture changes of coal samples before and after heating are compared to observe the penetration effect of microwaves on coal samples. Based on the technology of directional drilling and continuous tubing technology in petroleum engineering, a technology of increasing the production of coalbed methane by microwave heating in a wide range of coal seams is proposed. The feasibility of this enhanced production method is validated through COMSOL Multiphysics simulations, which model the temperature field distribution within coal seams under various microwave parameters. This approach highlights the potential of microwave technology in coalbed methane recovery. The results show that: (1) the thermal field of coal samples under microwave heating is inhomogeneous. The average length and area of the cracks of the coal samples increased under microwave radiation, and the cracking of the coal samples confirmed the cracking effect of microwaves on the coal samples. (2) With prolonged microwave heating, coal samples exhibit an initial decrease followed by an increase in porosity and permeability, a trend attributed to the expansion of solid particles that occupy and reduce pore spaces. (3) The in-situ microwave heating technique for coalbed methane extraction overcomes the challenges of long-distance microwave transmission loss and methane backflow in transmission pipelines, utilizing continuous pipelines for extensive microwave heating of coal seams. (4) The microwave power and intermittent heating duration have a significant effect on the temperature field distribution of the coal seam, and when the heating duration is 60 days, 1600 W is used to have an effective temperature field distribution while avoiding the waste of heat. When the power is constant at 1600 W, the effective temperature range is wider when the intermittent heating duration is 60 days.
Calcium-based nanowires for bone repair
Authors: Sun Yuqi , Wang Yuanbo
Published: September 2024

Bone defects due to the older population, severe trauma, congenital malformations, resection of bone tumors, and infections are serious problems faced in orthopedic clinical treatment, posing great hazards to human health and life, and external interventions are generally required to promote bone healing. Considering the osteogenic promotion of calcium ions, Ca-POM nanowires were synthesized in this study to facilitate the osteogenesis process through the release of calcium ions. The cytotoxicity test showed that the material possesses good biocompatibility. Furthermore, the Alizarin Red S staining demonstrated that the material could promote osteogenesis, indicating its potential as an ideal candidate for bone repair.
Service performance of nitrile rubber sealing ring under 70 MPa high-pressure hydrogen
Authors: Lei Xiaozhen , Zheng Bin
Published: September 2024

The service performance of NBR seals under 70 MPa high-pressure hydrogen was investigated, and the effects of vulcanization additives, fillers, and crude systems on their sealing performance were investigated. The sealing performance was characterized by the changes in volume and hardness before and after the service of the seals.
Mechanical integrity analysis of caprock during the CO2 injection phase
Authors: Liu Bin , Huang Tiantian
Published: September 2024

CO2 geological storage is one of the important means to mitigate the greenhouse effect. The safe underground storage of CO2 largely depends on the mechanical integrity of the caprock. This paper establishes a fluid-solid coupling model for CO2 geological storage to study the changes in pore pressure, vertical displacement, and effective stress in the caprock during the CO2 injection process. Combined with the Mohr-Coulomb criterion, the study determines whether mechanical failure occurs in the caprock. The results indicate that, at the beginning of CO2 injection, significant changes occur in the pore pressure, vertical displacement, and effective stress at the bottom of the caprock near the injection well, which then tend to stabilize; the maximum pore pressure at the bottom of the caprock reaches 36.08 MPa; the caprock near the injection well is considered the most critical area, where the risk of mechanical failure is highest; at the end of CO2 injection, the stress state does not reach the limit, and the caprock remains stable.
Optimization of Bacillus licheniformis’ nutrient system and oilfield trial for MEOR
Authors: Kang Dingyu , Sun Duo , Yao Zixun , Zhang Zhongzhi , Zhang Zhiyong
Published: September 2024

The efficacy of microbial-enhanced oil recovery (MEOR) is contingent upon the performance of oil recovery functional bacteria. The optimization of the nutrient system for oil recovery functional bacteria can enhance their performance. In this study, the nutrient systems of the strains underwent screening and optimization procedures, utilizing single-factor combined with response surface methodology. Subsequently, field trials were conducted to assess the efficacy of MEOR. The results indicated that the carbon source in the nutrient system was sucrose, the nitrogen source was NaNO3, and the phosphorus source was a combination of KH2PO4 and Na2HPO4 (in a 1:1 ratio). The combination of the results from the single-factor experiments and the response surface experiment led to the following formulation for the strain F-T nutrient system (g/L): sucrose 10.0, NaNO3 2.0, KH2PO4 1.5, Na2HPO4 1.5, CaCl2 0.12, FeSO4 0.12, MgSO4·7H2O 0.2, Na2MoO4 0.08, yeast powder 1.0, and pH 7.2-7.5. The optimized F-T bacterium has the potential to spread oil up to a diameter of 40.50 mm. The results of the MEOR field trial indicated a 2.95 × 10 t increase in oil production, with a success rate of 83.87%. Following the implementation of MEOR, production levels were observed to decline to levels comparable to those observed prior to the intervention. This indicates that continued MEOR field applications may be necessary to further enhance crude oil recovery.
Enhanced heat transfer technology for solar air heaters
Authors: Yang Aixin , Zhang Chunxia
Published: September 2024

Solar air heaters (SAHs) exhibited low thermal performance due to air thermal properties. To optimize the convective heat transfer between air and the absorber plate, researchers designed plenty of enhanced structures based on experimental and numerical analysis. This article reviewed the improvement methods of SAHs and emphasized the crucial role of thermodynamic models and evaluation criteria. Current research focuses on improving the convective heat transfer coefficient. In terms of enhanced structures, using flow deflectors, flow disruptors, corrugated absorber plates, and porous media improved collection efficiency. This result showed these enhanced structures could effectively further the performance of SAHs and provide new ways for sustainable energy utilization.
Efficient Co-ZrO2 electrocatalyst achieves high-performance solid-state lithium-sulfur batteries
Authors: Ma Yanyan , Yan Jianhua
Published: September 2024

Li-S batteries are recognized as a promising secondary battery system because of their high energy density, low cost, and environmental friendliness. However, the development of Li-S batteries is mainly limited by issues such as electrode volume expansion, lithium polysulfide (LiPSs) shuttle, and slow redox reaction kinetics of sulfur. Here, a kind of solid-state Li-S battery with in situ solidified solid-state electrolytes (SSEs) is reported, which dramatically reduces the electrode/electrolyte interfacial impedance. In addition, electrospinning is used to fabricate a macroporous carbon nanofibers film (MP-CNFs) loaded with dispersed Co-ZrO2 nanodot electrocatalyst as the cathode host. The in-situ gel electrolyte can be easily infiltrated into the porous carbon nanofibers and contact the Co-ZrO2 catalyst, thus fully exerting its catalytic and conversion effects on LiPSs. The results indicate that solid-state Li-S batteries exhibit a high initial capacity of 795.5 mA h·g−1 and a capacity retention rate of ∼100% after 200 cycles at 1 C.
Effect of microwaves on the repair of lead-acid batteries
Authors: Hou Desheng , Li Fengxiu , Zhang Yiming , Luo Jianwen , Wu Haoran , Gou Dezhi , Tang Zhengming
Published: September 2024

Lead-acid batteries are widely used in the automotive industry, and a large amount of waste lead-acid batteries cause enormous pressure on resources and the environment. Repairing aging lead-acid batteries is an effective way to solve this problem. Due to the fact that microwaves can affect most chemical reactions and promote their progress, this paper will study the repair effect of microwaves on lead-acid batteries by combining theory and experiment methods. By analyzing the reaction principle of lead-acid batteries, a multi-physics model is established to study the influence of microwaves on the lead-acid batteries, and an experimental system is built to test the changes in capacity and final charge voltage of lead-acid batteries under the radiation of microwaves. The results demonstrate that microwave treatment significantly enhances the capacity of aging lead-acid batteries, particularly when the initial capacity is slightly above 50% of the rated capacity. Moreover, heating the battery with hot air alone hardly affects its capacity. This study reveals that microwaves have reparative effects on lead-acid batteries, providing a new method for repairing aging batteries.
Performance assessment of deep borehole heat exchanger heating system under different heating modes
Authors: Zhu Chao , Shi Peng , Zhang Tuo , Li Zhuang , Quan Chen , Li Feng , Xia Qing
Published: September 2024

With the transition towards renewable energy sources, particularly as we move away from fossil fuels, there has been a constant evolution of deep borehole heat exchanger (DBHE) coupled heat pump heating technology. On the basis of the heat-exchanging properties of circulating fluid in the DBHE heating system, this paper clarifies the setup forms of this system, and elucidates the influence of heat extraction performance. After analysis and research, it can be concluded that the direct supply mode shows a more prominent decline in water temperature compared to the coupled heat pump and coupled plate heat exchanger modes. The imported and exported water temperatures when heating ends were recorded as 9.98°C and 16°C, respectively. The imported and exported water temperatures for both the direct supply and the coupled plate heat exchanger modes tend to be similar at 19.6°C and 25.5°C at a temperature of 7°C. Heat pump not only enhances the heat exchange features of ground source heat pump (GSHP) heating system, but also defines the configuration of heat extraction performance of DBHE. The system power consumption in the coupled plate heat exchanger mode is lower than that in the heat pump mode which is conducive to stable operation. Therefore, the best design form of the DBHE Heating System is the heat pump coupled plate exchange mode.
Analysis of seismic damage mechanism of capacitor
Authors: Min Qingyun , Hong Zhihu , Zou Dexu , Zhou Fangrong , Zhu Longchang , Dai Weiju , Yan Jingyi , Sun Haoruo , Xie Qiang
Published: September 2024

A high voltage shunt capacitor bank is very important for the normal operation of the power system, especially for the UHVDC transmission in long distance large capacity transmission, and power system networking has an important role. Therefore, its performance response under earthquakes is one of the key concerns. Through the fine finite element simulation modeling of the actual capacitor, the sine beat wave, and the actual earthquake input, the dynamic characteristics and the response index under the earthquake are studied. The results show that the stiffness in the x direction of the capacitor assembly is greater than that in the y direction. The weak position of the model is the root and top of the end insulator and the middle insulator. Under the action of different working conditions, such as X - and Y-El Centro waves, the maximum stress response of the root of the end insulator of the capacitor device is 4.98 MPa, and the safety factor is 3.51, which meets the requirement greater than 1.67.
No deceleration signs in the permafrost ground subsidence four years after the 2019 fire in Northwest Territories, Canada
Authors: Cao Zetao , Furuya Masato
Published: September 2024

The circum-arctic permafrost environment is often disturbed by wildfires but could also show resilience to these disturbances. However, the increased frequency and extent of wildfires, coupled with unprecedented hot weather, have introduced greater uncertainties in the post-fire permafrost dynamics. We need to address emerging questions, e.g. How will permafrost respond to the joint effect of hot anomalies and wildfires? To what extent will post-wildfire deformation evolve? How will permafrost resilience to wildfires vary? Utilizing interferometric synthetic aperture radar time series analysis, we investigated the post-wildfire ground deformation around a 2019 fire scar in the lower Mackenzie Valley, Northwest Territories, Canada, where dramatic heat anomalies and severe wildfires have been recorded in recent years. The resilience of permafrost to wildfires appears to be weakened by the continuous and rapid warming after the fire, as evidenced by the year-on-year acceleration in subsidence rates. Such acceleration was never reported by previous findings that typically observed deceleration in subsidence rates four to five years after wildfires. The deformation along the line of sight (LOS) of the satellite demonstrates significant permafrost degradation induced by wildfires and exacerbated by climate warming, and the cumulative subsidence was detected up to 25 cm in the LOS direction in the upland areas and up to 10 cm in the lowland areas four years after the fire. The difference in deformation magnitude could be attributed to local factors, including ground ice, topography, and vegetation. Our study highlights the increasingly severe threat to circum-arctic permafrost due to the combined effects of wildfires and extreme heat anomalies.
Multiscale computational modeling techniques in study and design of 2D materials: recent advances, challenges, and opportunities
Authors: Asle Zaeem Mohsen , Thomas Siby , Kavousi Sepideh , Zhang Ning , Mukhopadhyay Tanmoy , Mahata Avik
Published: September 2024

This article provides an overview of recent advances, challenges, and opportunities in multiscale computational modeling techniques for study and design of two-dimensional (2D) materials. We discuss the role of computational modeling in understanding the structures and properties of 2D materials, followed by a review of various length-scale models aiding in their synthesis. We present an integration of multiscale computational techniques for study and design of 2D materials, including density functional theory, molecular dynamics, phase-field modeling, continuum-based molecular mechanics, and machine learning. The study focuses on recent advancements, challenges, and future prospects in modeling techniques tailored for emerging 2D materials. Key challenges include accurately capturing intricate behaviors across various scales and environments. Conversely, opportunities lie in enhancing predictive capabilities to accelerate materials discovery for applications spanning from electronics, photonics, energy storage, catalysis, and nanomechanical devices. Through this comprehensive review, our aim is to provide a roadmap for future research in multiscale computational modeling and simulation of 2D materials.
Study of radiation-induced structural changes in the near-surface layer of ZrO2 ceramics caused by He2+ irradiation
Authors: Kozlovskiy Artem L , Borgekov Daryn B , Ivanov Igor A , Zdorovets Maxim V
Published: September 2024

The aim of this study is to determine changes in the near-surface layer of ZrO2 ceramics caused by irradiation with low-energy He2+ ions, as well as the associated formation of defects and structural deformations. During the experimental work conducted, it was established that the accumulation of deformation-structural distortions is of two stage nature, having a direct dependence on irradiation fluence and, therefore, on atomic displacement value. It was determined that at small atomic displacement values (less than 10 dpa), the main mechanisms of structural distortions are caused by tensile residual stresses, the value of which is less than 0.1 GPa. At the same time, the deformation distortion of chemical bonds has a pronounced anisotropy associated with a more pronounced distortion of the Zr–OI chemical bonds, the distortion of which results in the formation of vacancy defects in the form of VO. During determination of alterations in optical characteristics depending on the atomic displacement value, it was found that the dominant role at small values of dpa (less than 10 dpa) is played by point defects, which influence the formation of obstacles in the form of absorbing centers. In this case, an increase in the irradiation fluence above 1017 ion cm−2 results in a growth in the linear refractive index, the change of which has a direct correlation with the value of residual stresses in the damaged layer. Certain dependencies of changes in structural features and their relationship with deformation distortions, as well as the accumulation of vacancy defects, can subsequently be used to predict the potential of using these ceramics as materials for new generation nuclear reactors.
Microstructure and mechanical properties of TiC reinforced NbC-Ni4VC4Mo2C cermets
Authors: Malik Asad , Basit Abdul , Ijaz Muhammad Farzik , Anwar Furqan , Umer Malik Adeel , Shao Yang
Published: September 2024

The class of NbC-Ni cermets has emerged as a promising environmentally friendly alternative to WC-Co cemented carbide tools, although some inherent properties i.e. room temperature hardness and flexural strength, of NbC-Ni cermets may require further enhancements. To enhance the properties of NbC-Ni cermets, diverse methodologies were applied, including grain inhibition and the strengthening of the cermet through the use of reinforcements. This study systematically examined the impact of TiC additions, specifically at 10% and 20%, on both the microstructure and mechanical properties of NbC-12Ni-4VC-4Mo2C cermets. NbC-12Ni cermets were fabricated via vacuum liquid phase sintering (LPS) at 1400 °C and 1450 °C. Enhancements by incorporating 4% VC and 4% Mo2C, followed by TiC at 10% and 20% concentrations to the NbC-Ni-4VC4Mo2C cermet were made. XRD and SEM results confirm the formation of (Nb, X, Y) C solid solution cubic FCC carbides. Significant grain refinement was evident in the cermet samples, subjected to grain inhibition. The observed grain sizes ranged from a maximum of 6.84 μm (in NbC12Ni) to a minimum of 2.154 μm (in the sample containing 20% TiC) at 1450 °C. The incorporation of 20TiC at 1450 °C led to a remarkable 26.5% enhancement in average hardness compared to NbC-Ni cermet, and a 4.2% improvement over the 4VC4Mo2C cermet. At 1450 °C, 20TiC reinforcement led to an average fracture toughness of 9.331 MPa√m, representing a 4.56% improvement over the 4VC4Mo2C cermet. However, there was a marginal reduction in toughness compared to the NbC-Ni cermet. Moreover, the addition of TiC led to a decrease in the flexural strength of the cermets, with a maximum flexural strength of 939 N mm−2 recorded for NbC-Ni-4VC4Mo2C, representing an 11.6% increase compared to the NbC-Ni cermet.
Precursor boundary layer conditions for shallow and deep convection: inferences from CAIPEEX field measurements over the Indian Peninsula
Authors: Gayatri K , Malap Neelam , Murugavel P , Karipot A , Prabhakaran Thara
Published: September 2024

The diurnal cycle of environmental conditions for shallow and deep convection regimes within the Indian monsoon environment is investigated using comprehensive observations from the surface, boundary layer, and cloud layers. For shallow convection (SC) and deep convection (DC) in the afternoon hours, thermodynamics, moisture convergence, and several other environmental variables provide information on the factors that control the vertical extent of convection in both regimes. The SC regime is characterized by high sensible heat flux, leading to stronger boundary layer turbulence, a higher mixed layer, and increased dry air entrainment from the free troposphere. Evaluation of several pre-conditioning parameters with T-test statistics suggests that stronger mid-level meridional wind shear and lack of mid-level moistening are detrimental to the growth of clouds in the SC regime. Conversely, the DC regime is driven by low surface fluxes and low surface-level buoyancy, with higher boundary layer and mid-layer moisture and more mid-layer instability, supporting larger Convective Available Potential Energy (CAPE). Morning precursor conditions for the preference of SC versus DC regime in the afternoon reveal that total column water vapor, relative humidity and CAPE are significantly higher on DC days. Large-scale moisture transport in the early morning within and above the boundary layer, driven by stronger westerly winds, is a key factor for the development of DC later in the day. This investigation enhances our understanding of boundary layer controls on shallow and deep convection within the Indian Monsoon environment.
Soil characterization, CBR modeling, and spatial variability analysis for road subgrade: a case study of Danchuwa – Jajere Road, Yobe State, Nigeria
Authors: Umar Ibrahim Haruna , Salisu Ibrahim Mu’azzam , Lin Hang , Hassan Jubril Izge
Published: September 2024

Road construction projects require a thorough understanding of soil properties to ensure the stability and longevity of the infrastructure. This study investigates soil properties along a proposed 34 km road alignment in Yobe State, Nigeria, to characterize soil variability for road construction and develop a predictive model for California Bearing Ratio (CBR). Of the 34 soil samples analyzed, 30 were classified as A-3(1) and four as A-1(1) according to the AASHTO system. Geotechnical testing, including particle size distribution (grading percentages: gravel 0.02%–75.34%, sand 15.5%–90.88%, fines 8.92%–34.84%), Atterberg limits (liquid limits 17%–33%, plastic limits 14%–27%, plasticity index <12%), specific gravity (2.01 to 2.73), compaction (maximum dry density 1.83–2.19 Mg m−3, optimum moisture content 7.29%–14.42%), and CBR tests (values ranging from 5%–62%), were conducted. Correlation analyses revealed strong positive relationships between maximum dry density (r = 0.82) and specific gravity (r = 0.89) with CBR values. Cluster analysis segmented the samples into four distinct groups: Cluster 0 (11 samples), Cluster 1 (9 samples), Cluster 2 (5 samples), and Cluster 3 (9 samples). A linear regression model predicted CBR using maximum dry density and specific gravity (mean squared error = 9.82, R2 = 0.92). Based on CBR criteria, 8 out of 34 samples (CBR 20%–53%) satisfied subbase requirements, while none met the recommended minimum CBR of 80% for base course materials. This study enhances road construction planning through soil variability analysis, effective soil categorization via cluster analysis, and a reliable CBR prediction model. While on-site materials are unsuitable for subgrade and subbase layers, alternative materials or ground improvement techniques are recommended for the base course layer to enhance bearing capacity.