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Controllable synthesis of one-dimensional silicon nanostructures based on the dual effects of electro-deoxidation and the Kirkendall effect

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Nano Research 2024年第9期17卷 7814-7823页

作者： Jianxin Tu Shuo Yu Kui Hao Le Sun Ruicheng Bai Fangzhou Zhang Aijun Li Hong Liu Institute of Materials School of Materials Science and EngineeringShanghai UniversityShanghai 200444China Department of Applied Physics The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shaoxing institute of technology Shanghai UniversityShanghai 200444China

In this study,we successfully synthesized silicon nanotubes(Si-NTs)and silicon nanowires(Si-NWs)in a controllable manner using a catalyst-and template-free method through the direct electrolysis of SiO_(2)in a molten CaCl_(2)-CaO system,while also proposing a novel formation mechanism for ***-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO_(2)decomposition *** subsequently adjusting the voltage to a value between the decomposition potentials of CaCl_(2)and CaO,in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs,leading to the formation of a Ca *** formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs,as the outward diffusion rate of Si exceeds the inward diffusion rate of *** differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall *** vacancies gradually accumulate and merge,forming large voids,which ultimately result in the formation of hollow *** a subsequent dealloying process,the removal of the embedded calcium leads to the formation of *** the application of a carbon coating,the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g^(-1)at 1.5 A·g^(-1)and exhibits exceptional long-term cycling stability,maintaining a capacity of 977 mAh·g^(-1)after 2000 cycles at 3.0 A·g^(-1).

关键词： silicon nanotubes silicon nanowires lithium-ion battery Kirkendall effect

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Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

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Petroleum science 2024年第3期21卷 2048-2065页

作者： Qing-Ping Li Jin-Ya Zhang Jia-Xiang Zhang Yong-Xue Zhang CNOOC Research Institute Company Limited Beijing100028China State Key Laboratory of Natural Gas Hydrate Beijing100028China College of Mechanical and Transportation Engineering China University of PetroleumBeijing2249China

Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump *** mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation ***(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh *** results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually *** the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely *** maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance *** mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial *** with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and *** actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

关键词： Multiphase pump Liquid film seal Pressure disturbance wave Dynamic response characteristics

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Photoinduced superlubricity on TiO_(2) surfaces

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Friction 2024年第3期12卷 428-438页

作者： Ke HAN Liran MA Yu TIAN Jianbin LUO State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Received:16 September 2022/Revised:28 October 2022/Accepted:27 December 2022The author(s)2022.

Superlubricity control is of great interest in both industry and scientific research,and several methods have been proposed to achieve this *** this work,ultraviolet(UV)light was introduced into titanium dioxide(TiO_(2))and silicon nitride(Si_(3)N_(4))tribosystems to accomplish photoinduced *** friction coefficients(COFs)between Si_(3)N_(4) balls and TiO_(2) plates in the mixtures of sulfuric acid(H^(2)SO_(4))solution and glycerol solution were obviously reduced,and the system entered the superlubricity region(COF<0.01)after UV illumination at a speed of 56 mm/***,the COF was much larger without UV treatment than that with UV *** formation of silica(SiO_(2))layers on the surfaces of Si_(3)N_(4) balls and the elastohydrodynamic effects were determined to be fundamental to the low friction in this experiment,and the enhancement of the combination between the TiO_(2) surface and the hydroxy group of glycerol by UV illumination was the key to the photoinduced superlubricity in this *** findings showed one method for achieving superlubricity by introducing a light field that could be further applied to special working conditions.

关键词： light control friction superlubricity glycerol titanium dioxide(TiO_(2))

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Low friction under ultrahigh contact pressure enabled by self-assembled fluorinated azobenzene layers

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Friction 2024年第7期12卷 1434-1448页

作者： Dandan XUE Zhi XU Linyuan GUO Wendi LUO Liran MA Yu TIAN Ming MA Qingdao ZENG Ke DENG Wenjing ZHANG Yichun XIA Shizhu WEN Jianbin LUO State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China national Center for Nanoscience and Technology Beijing 100190China

Extensive efforts have been made to pursue a low-friction state with promising applications in many fields,such as mechanical and biomedical *** which,the load capacity of the low-friction state has been considered to be crucial for industrial ***,we report a low friction under ultrahigh contact pressure by building a novel self-assembled fluorinated azobenzene layer on an atomically smooth highly-oriented pyrolytic graphite(HOPG)*** friction coefficients could be as low as 0.0005 or even lower under a contact pressure of up to 4 *** demonstrates that the low friction under ultrahigh contact pressure is attributed to molecular *** fluorination leads to effective and robust lubrication between the tip and the self-assembled layer and enhances tighter rigidity which can reduce the stress concentration in the substrate,which was verified by density functional theory(DFT)and molecular dynamics(MD)*** work provides a new approach to avoid the failure of ultralow friction coefficient under relatively high contact pressure,which has promising potential application value in the future.

关键词： ultrahigh contact pressure self-assembled layer fluorination robust lubrication

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Review Article Li-current collector interface in lithium metal batteries

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Nano Research 2024年第10期17卷 8706-8728页

作者： Tian-Yu Wang Dingyi Zhao Keyue Liang Yuzhang Li Department of Chemical and Biomolecular Engineering University of CaliforniaLos AngelesLos AngelesCalifornia 90095USA

Interfaces within batteries,such as the widely studied solid electrolyte interface(SEI),profoundly influence battery *** these interfaces,the solid-solid interface between electrode materials and current collectors is crucial to battery performance but has received less discussion and *** review highlights the latest research advancements on the solid-solid interface between lithium metal(the next-generation anode)and current collectors(typically copper),focusing on factors affecting the Li-current collector interface and improvement strategies from perspectives of current collector substrate(lithiophilicity,crystal facets,mechanical properties,and topological structure),electrolyte chemistry,current density,stacking pressure,SEI,electric field and temperature,and provides a future directions and opportunities on this topic.

关键词： lithium metal anode current collectors Li-current collector interface solid-solid interface improvement strategies

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Dual-functional poly(2-methyl-2-oxazoline)/poly(2-(dimethylamine)ethyl methacrylate)mixed brushes with switchable protein adsorption and antibacterial properties

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Chinese Journal of Chemical Engineering 2024年第2期66卷 19-30页

作者： Kang He Liangyu Zhu Yanmei Wang CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated PMOXA and SH-terminated PDMAEMA onto polydopamine-anchored *** mixed-brush coating was characterized by variable-angle spectroscopic ellipsometry,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,zeta potential measurements,water contact angle,and atomic force *** mixed brushes showed tunable surface charge,wettability,and surface roughness,depending on the degree of PDMAEMA swelling under varying pH and ionic strength(Ⅰ).Then the adsorption behaviors of pepsin,bovine serum albumin(BSA),γ-globulin,and lysozyme,four very different proteins with regard to isoelectric point,on the mixed brushes coating were studied by using fluorescence microscopy and surface plasmon *** the chain length of PDMAEMA was about twice as long as PMOXA,the mixed brushes not only had high adsorption capacity for pepsin,BSA,and y-globulin but also had a desorption efficiency of 86.9%,87.1%,and 93.5%,*** is explained that electrostatic attraction between the protonated PDMAEMA and positively charged acidic proteins(pepsin and BSA,whose isoelectric points were below the pK_(a) of PDMAEMA)would drive the intensive adsorption(at pH 3,I=10^(-3)mol·L^(-1)for pepsin,and pH 5,I=10^(-5)mol·L^(-1)for BSA),while desorption was dominated by the hydrophilic PMOXA when PDMAEMA was shrinking(at pH 7,I=10^(-1)mol·L^(-1)for pepsin,and pH 9,I=10^(-1)mol·L^(-1)for BSA).Furthermore,the isoelectric precipitation led to the adsorption of neutral protein(γ-globulin,whose isoelectric point was near the pK_a of PDMAEMA)at pH 7,I=10^(-5)mol·L^(-1),while electrostatic repulsion and antifouling PMOXA triggered the desorption of y-globulin at pH 3,I-10^(-1)mol·L^(-1).However,alkaline protein(lysozyme,whose isoelectric point was higher than

关键词： Switchable conformation transition Controllable protein adsorption Mixed brushes Isoelectric point Antibacterial surface

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Investigation of non-uniform leading-edge tubercles in compressor cascade:Based on multi-objective optimization and data mining

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Chinese Journal of Aeronautics 2024年第7期37卷 134-152页

作者： Jiezhong DONG Wuli CHU Haoguang ZHANG Bo LUO Tianyuan JI Ziyun ZHANG School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China

Corner stall receives noticeable attention in the aeroengine field as an important phenomenon in highly-load ***-uniform leading-edge tubercles,as an effective method to delay stall,are introduced into the *** this paper,the shape of leading-edge tubercles was controlled by a third-order Fourier *** judge corner stall,a more precise stall indicator for compressor cascade with flow control methods was ***,the total kinetic energy of the secondary flow at large incidence was adopted as a parameter for stall evaluation to save computing *** results of multiobjective optimization reveal that the loss coefficient exhibited negligible variation at design incidence,while the total kinetic energy of secondary flow showed a significant reduction at large incidence,resulting in a substantial increase in stall *** the optimal profiling cases,the stall incidencewas delayed from 7.9°to 11.6°.The major purpose of the research is to provide proper design guidelines for nonuniformleading-edge tubercles and uncover the flow controlmechanisms of leading-edge ***,the geometric features that meet different optimization objectives were extracted through geometric analysis near the Pareto Front and through Self-OrganizingMap(SOM)dataminingmethods in the optimization ***,flow field analysis reveals the flow control mechanism of leading-edge *** convex-concave-convex structure at the 0%-70%blade height region can form two branches of leading-edge vortex pairs that are opposite in the rotation direction to the passage *** two branches of leading-edge vortex pairs mixed with the leading-edge separation vortex to form two stronger mixed vortices,which can effectively suppress the development of passage vortex and delay stall incidence.

关键词： Corner stall Non-uniform leading-edge tubercles Stall indicator Stall evaluation parameter Mixed vortex

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In Situ High-performance Gel Polymer Electrolyte with Dual-reactive Cross-linking for Lithium Metal Batteries

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Energy & Environmental Materials 2024年第1期7卷 51-59页

作者： Fuhe Wang Honghao Liu Yaqing Guo Qigao Han Ping Lou Long Li Jianjie Jiang Shijie Cheng Yuancheng Cao School of Materials science and Engineering Huazhong University Huazhong University of science and Technology Wuhan 430074China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and TechnologyWuhan 430074China State Grid Huzhou Power Supply Company Huzhou 313000China Huzhou Electric Power Design Institute Company Huzhou 311404China

Lithium metal batteries have been considered as one of the most promising next-generation power-support devices due to their high specific energy and output ***,the uncontrollable side-reaction and lithium dendrite growth lead to the limited serving life and hinder the practical application of lithium metal ***,a tri-monomer copolymerized gel polymer electrolyte(TGPE)with a cross-linked reticulation structure was prepared by introducing a cross-linker(polyurethane group)into the acrylate-based in situ polymerization *** soft segment of polyurethane in TGPE enables the far migration of lithium ions,and the-NH forms hydrogen bonds in the hard segment to build a stable cross-linked *** system hinders anion migration and leads to a high Li^(+)migration number(t_(Li^(+))=0.65),which achieves uniform lithium deposition and effectively inhibits lithium dendrite *** a result,the assembled symmetric cell shows robust reversibility over 5500 h at a current density of 1 mA cm^(-2).The LFP∷TGPE∷Li cell has a capacity retention of 89.8%after cycling 800 times at a rate of *** summary,in situ polymerization of TGPE electrolytes is expected to be a candidate material for high-energy-density lithium metal batteries.

关键词： gel polymer electrolytes hydrogen bonds in situ polymerization lithium metal batteries polyurethane

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Random Green's Function Method for Large-Scale Electronic Structure Calculation

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Chinese Physics Letters 2024年第5期41卷 23-29页

作者：汤明发刘畅张爱霞张青云翟佳羽袁声军柯友启 School of Physical science and Technology ShanghaiTech UniversityShanghai 201210China Xiaogan Sichuang Information Technology Co. LTDXiaogan 432000China Institute of Mathematical sciences ShanghaiTech UniversityShanghai 201210China Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and TechnologyWuhan UniversityWuhan 430072China Wuhan Institute of Quantum Technology Wuhan 430206China

We report a linear-scaling random Green's function(rGF) method for large-scale electronic structure calculation. In this method, the rGF is defined on a set of random states and is efficiently calculated by projecting onto Krylov subspace. With the rGF method, the Fermi–Dirac operator can be obtained directly, avoiding the polynomial expansion to Fermi–Dirac function. To demonstrate the applicability, we implement the rGF method with the density-functional tight-binding method. It is shown that the Krylov subspace can maintain at small size for materials with different gaps at zero temperature, including H_(2)O and Si clusters. We find with a simple deflation technique that the rGF self-consistent calculation of H_(2)O clusters at T = 0 K can reach an error of~ 1 me V per H_(2)O molecule in total energy, compared to deterministic calculations. The rGF method provides an effective stochastic method for large-scale electronic structure simulation.

关键词： calculation function method

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Quasi-in-situ Observation and SKPFM Studies on Phosphate Protective Film and Surface Micro-Galvanic Corrosion in Biological Mg-3Zn-xNd Alloys

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 648-664页

作者： Zhaochen Yu Kaixuan Feng Shuyun Deng Yang Chen Hong Yan Honggun Song Chao Luo Zhi Hu School of Advanced Manufacturing Nanchang UniversityNanchang330031China Institute for Advanced Study Nanchang UniversityNanchang330031China

The phosphate protective film and micro-galvanic corrosion of biological Mg-3Zn-xNd (x = 0, 0.6, 1.2) alloys were investigated by scanning and transmission electron microscopy, quasi-in-situ observation, scanning Kelvin probe force microscopy (SKPFM) and electrochemical tests. The results revealed the Mg-Zn-Nd phases formed in Mg-3Zn alloy contained with Nd. Adding Nd resulted in a significant decline in the cracks of the phosphate protective film and micro-galvanic corrosion of alloys, which were recorded by quasi-in-situ observation. In addition, the Volta potential difference of Mg-Zn-Nd/α-Mg (~ 188 mV) was lower than MgZn/α-Mg (~ 419 mV) and Zn-rich/α-Mg (~ 260 mV), and the corrosion rates of alloys markedly decreased after the addition of 0.6 wt% Nd. The improvement in corrosion resistance of Nd-containing alloys was mainly attributed to the following: (i) the addition of Nd reduced the Volta potential difference (second phases/α-Mg);(ii) the phosphate protective film containing Nd_(2)O_(3) deposited on the surface of the alloys, effectively preventing the penetration of harmful anions.

关键词： Magnesium alloys Quasi-in-situ observation Phosphate protective film Scanning Kelvin probe force microscopy(SKPFM) Micro-galvanic corrosion

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