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Exploring the Cation Regulation Mechanism for Interfacial Water Involved in the Hydrogen Evolution Reaction by In Situ Raman Spectroscopy

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Nano-Micro Letters 2024年第3期16卷 303-312页

作者： Xueqiu You Dongao zhang Xia‑guang zhang Xiangyu Li Jing‑Hua Tian Yao‑Hui Wang jian‑Feng Li School of Ocean Information Engineering Fujian Provincial Key Laboratory of Oceanic Information Perception and Intelligent ProcessingJimei UniversityXiamen 361021People’s Republic of China State Key Laboratory of Physical Chemistry of Solid Surfaces MOE Key Laboratory of Spectrochemical Analysis and InstrumentationiChEMCollege of Chemistry and Chemical EngineeringCollege of MaterialsCollege of EnergyXiamen UniversityXiamen 361005People’s Republic of China Key Laboratory of Green Chemical Media and Reactions Ministry of EducationCollaborative Innovation Center of Henan Province for Green Manufacturing of Fine ChemicalsCollege of Chemistry and Chemical EngineeringHenan Normal UniversityXinxiang 453007People’s Republic of China Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) Xiamen 361005People’s Republic of China

Interfacial water molecules are the most important participants in the hydrogen evolution reaction(HER).Hence,understanding the behavior and role that interfacial water plays will ultimately reveal the HER ***,investigating interfacial water is extremely challenging owing to the interference caused by bulk water molecules and complexity of the interfacial ***,the behaviors of interfacial water in different cationic electrolytes on Pd surfaces were investigated by the electrochemistry,in situ core-shell nanostructure enhanced Raman spectroscopy and theoretical simulation *** spectral evidence reveals a red shift in the frequency and a decrease in the intensity of interfacial water as the potential is shifted in the positively *** comparing the different cation electrolyte systems at a given potential,the frequency of the interfacial water peak increases in the specified order:Li+

关键词： In situ Raman Interfacial water Hydrogen evolution reaction Cations

Current research on electrospinning of silk fibroin and its blends with natural and synthetic biodegradable polymers

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Frontiers of Materials Science 2013年第2期7卷 129-142页

作者： jian-guang zhang Xiu-Mei MO Biomaterials and Tissue Engineering Lab College of Chemistry Chemical Engineering & Biotechnology Donghua University Shanghai 201620 China

Silk fibroin （SF） is a kind of natural polymers with a great potential in biomedical application. Due to its good biocompatibility, biodegradability and minimal inflammatory reaction, SF is an excellent candidate for generating tissue engineering scaffolds. Electrospinning is a simple and effective method to fabricate nanofibers, which has several amazing characteristics such as very large surface area to volume ratio, flexibility in surface functionalities, and superior mechanical performance. The electro- spun nanofibers from SF and its blends have been used for varied tissue engineering. This paper will give a brief review about the structure, properties and applications of SF and blend nanofibers via electrospinning.

关键词： electrospinning nanofiber silk fibroin (SF) biodegradable polymer

Optimization of the co-closing law of guide vanes and blades for bulb turbines based on CFD

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Journal of Hydrodynamics 2024年第2期36卷 363-377页

作者： Hui Liu Yun-fa Lin Yong-guang Cheng Song Xue Mao-jia Tang jian zhang Jia-yi Fan State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China Dongfang Electric Machinery Co. Ltd.Deyang618000China

The load rejection transient process of bulb turbine units is critical to safety of hydropower stations,and determining appropriate closing laws of guide vanes(GVs)and runner blades(RBs)for this process is of *** this study,we proposed a procedure to optimize the co-closing law of GVs and RBs by using computational fluid dynamics(CFD),combined with the design of experiment(DOE)method,approximation model,and genetic optimization *** sensitivity of closing law parameters on the histories of head,speed,and thrust was analyzed,and a two-stage GVs’closing law associating with a linear RBs’closing law was *** results show that GVs dominate the transient characteristics by controlling the change of *** GVs’first-stage closing speed while shortening first-stage closing time can not only significantly reduce the maximum rotational speed but also suppress the water hammer pressure;slowing GVs’second-stage closing speed is conducive to controlling the maximum reverse axial *** directly affect the runner *** RBs’closing speed can further reduce the rotational speed and the maximum reverse axial *** safety margin of each control parameter,flow patterns,and pressure pulsations of a practical hydropower station were all improved after optimization,demonstrating the effectiveness of this method.

关键词： Bulb turbine load rejection transient process double regulation closing law optimization computational fluid dynamics(CFD)

Essential Players in Cooperative Games with Graph Communication Structure

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Journal of the Operations Research Society of China 2024年第1期12卷 93-108页

作者： guang zhang Jing-Yi Ge Business School University of Shanghai for Science and TechnologyShanghai200093China

A class of cooperative games with graph communication structure is studied in this paper by considering some important players,namely essential *** the assumption that only connected coalitions containing essential players are able to cooperate and obtain their worths,the class of graph games with essential players is proposed as well as an allocation *** proposed value follows the spirit of the Myerson value defined by applying the Shapley value on a modified *** properties,feasible component efficiency,the inessential component property,and fairness,are provided to fully characterize this value,where feasible component efficiency and fairness follows the same ideas of component efficiency and fairness for classical graph games,and the inessential component property says that the total payoffs of the players in a non-feasible component is ***,some computational aspects of the proposed value and comparisons with disjunctive permission value for games with permission structure are also studied,respectively.

关键词： Cooperative game Graph structure Essential player Myerson value Computation Permission structure

Recent progress in carbene-catalyzed fluoroalkylation

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Science China Chemistry 2024年第8期67卷 2448-2460页

作者： Bei zhang Xuan zhang jian Wang jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science and TechnologyNanjing 210044China School of Pharmaceutical Sciences Tsinghua UniversityBeijing 100084China

The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of fluoroalkyl groups into the chemical skeletons can cause considerable alternations in the chemical, physical and biological properties of molecules, which has attracted numerous scientists from different fields. This review focuses on N-heterocyclic carbene(NHC)-catalyzed fluoroalkylation reactions, providing a detailed analysis and summary of the achievements in the past two decades. Many successful examples clearly indicate that NHCs can catalyze the tranformation of fluoroalkylation reagents with various electronic characteristics, whether electrophilic, nucleophilic, or radical precursors. Herein, the fluoroalkylation reactions are classified based on different catalytic modes of NHCs: Lewis base catalysis, Umploung catalysis, radical catalysis and others. Meanwhile, by refining and systematically studying the contribution of NHC catalysis in fluoroalkylation reactions, this review is expected to provide valuable insights and enlightenment for related fields.

关键词： N-heterocyclic carbene fluoroalkylation radical catalysis

Conduction-convection coupled heat transfer around a hollow cylinder under different buoyancy forces

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Chinese Journal of Aeronautics 2024年第4期37卷 216-228页

作者： Wanyu zhang Jingyi WU guang YANG Institute of Refrigeration and Cryogenics Shanghai Jiao Tong UniversityShanghai 200240China

In order to clarify the effect of a buoyancy force on conduction–convection coupled heat transfer in a hollow cylinder, the flow and thermal characteristics were analyzed using an RNG k-ε turbulence model. The Reynolds number was fixed at 1.014 × 10^(6), and the Rayleigh number varied from 1.122 × 10^(10)to 1.088 × 10^(11). Results have shown that, when considering the effect of an opposed buoyancy force, increasing the Rayleigh number has a positive impact on the rate of change and uniformity of the cylinder temperature. The temperature distributions along the axial and circumferential directions are similar for different Rayleigh numbers, but extreme values *** the axial direction, the maximum temperature is obtained at the interface between the variable-diameter part and the constant-diameter part. The maximum dimensionless temperature value decreases to 0.12 when the Rayleigh number increases to 1.088 × 10^(11). Along the circumferential direction, the temperature distribution is affected by the buoyancy force, which results in the temperature of the upper part being higher than that of the lower part. After nondimensionalization of the temperature and time, a correlation was proposed to illustrate the transient heat transfer process quantitatively. The standard deviation of the maximum relative temperature, representing the temperature uniformity, was also calculated. It was found that the difference in the direction of the buoyancy force made a huge difference. Compared with the opposed buoyancy force, the maximum dimensionless temperature is almost two times higher with an assisted buoyancy force. Similarly, the heat transfer coefficient with an assisted buoyancy force is half of that with an opposed buoyancy force. Overall, an assisted buoyancy force plays a negative role in terms of thermal characteristics. The flow field around the hollow cylinder was also illustrated to reveal the mechanism of the buoyancy force on magnitude and direction aspects

关键词： Buoyancy Conduction-convection heat transfer Transient analysis Hollow cylinder Non-dimensionalization

Effect of cooling method on TiN precipitation behavior of high-titanium high-strength steel during solidification

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Journal of Iron and Steel Research(International) 2024年第7期31卷 1692-1703页

作者： Xue-jian zhang guang-wei Yang Yong Wan Yong-hong Wen Chuan-sheng Tang Ming-qi Liu Li-je Tian Key Laboratory of Metallurgical Emission Reduction and Resources Recycling Anhui University of TechnologyMa'anshan 243002AnhuiChina School of Metallurgical Engineering Anhui University of TechnologyMa'anshan 243002AnhuiChina Baosteel Central Research Institute Baoshan Iron and Steel Co.Ltd.Shanghai 201999China

Metallographic microscopy,scanning electron microscopy and TiN growth thermodynamic and kinetic equations were used to investigate the morphology,quantity,and size of TiN in the center of high-titanium high-strength steels under different solidification cooling *** results showed that TiN in the center of the experimental steels mainly existed in three forms:single,composite(Al2O3-TiN),and multi-particle *** began precipitating at around 1497℃(solidification fraction of 0.74).From the end of melting to solidification for 180 s,the cooling rates in the center of the experimental steels for furnace cooling,air cooling,refractory mold cooling,and cast iron mold cooling tended to stabilize at 0.17,0.93,1.65,and 2.15℃/s,*** size of TiN in the center of the experimental steel cooled using furnace cooling was mainly concentrated in the 5-15 pm *** contrast,the size of TiN in the center of the experimental steels cooled using air cooling,refractory mold cooling,and cast iron mold cooling were mainly concentrated in the 1-5 pm *** addition,their density of TiN in the center of the experimental steels is signif-icantly higher than that of the furnace-cooled experimental *** and kinetic precipitation models of TiN established predicted the growth size of TiN in a high-titanium high-strength steel when the solidification cooling rates are not below 0.93℃/s.

关键词： High-titanium steel Cooling method TiN Thermodynamics Kinetics

Nanophononic metamaterials induced proximity effect in heat flux regulation

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Frontiers of physics 2024年第2期19卷 149-156页

作者： jian zhang Haochun zhang Gang zhang School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Institute of High Performance Computing Agency for ScienceTechnology and Research(A*STAR)Singapore 138632Singapore

Recent studies have shown that the construction of nanophononic metamaterials can reduce thermal conductivity without affecting electrical properties,making them promising in many fields of application,such as energy conversion and thermal ***,although extensive studies have been carried out on thermal conductivity reduction in nanophononic metamaterials,the local heat flux characteristic is still *** this work,we construct a heat flux regulator which includes a silicon nanofilm with silicon *** regulator has remarkable heat flux regulation ability,and various impacts on the regulation ability are ***,even in the region without nanopillars,the local heat current is still lower than that in pristine silicon nanofilms,reduced by the neighboring nanopillars through the thermal proximity *** combine the analysis of the phonon participation ratio with the intensity of localized phonon modes to provide a clear *** findings not only provide insights into the mechanisms of heat flux regulation by nanophononic metamaterials,but also will open up new research directions to control local heat flux for a broad range of applications,including heat management,thermoelectric energy conversion,thermal cloak,and thermal concentrator.

关键词： nanophononic metamaterials proximity effect

Exhaust hood performance and its improvement technologies in industrial buildings:A literatu rereview

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Building Simulation 2024年第1期17卷 23-40页

作者： Jing zhang jian Wang Jun Gao Weimin zhang Architectural Engineering Institute Jinhua PolytechnicJinhua 321017China Institute of HVAC Engineering Schoolof Mechanical EngineeringTongji UniversityShanghai 200092China Tongji Architectural Design(Group)Co .LtdShanghai 200092China

The pollutant control performance of exhaust hoods plays a crucial role in the indoor air quality and energy consumption of ventilation systems in industrial *** better understand the impact of local ventilation on the industrial indoor environment,this paper presents a literature review of exhaust hood performance and its improvement *** create an index for evaluating the performance of exhaust hoods,the capture velocity,capture efficiency,flow ratio of pollutant emissions and exhaust airflow and energy consumption are first introduced.A number of factors affecting exhaust hood performance are assessed such as hood type,hood opening size,exhaust rate,installation distance,pollution source emission and environmental *** to structural improvement methods,the use of active airflow is a more effective way to improve the exhaust hood *** most commonly used methods for determining the exhaust rate are the controlled speed method and the flow ratio *** use of an exhaust hood with an appropriate exhaust rate and jet parameters(for an active air-assisted hood)can effectively improve the pollutant control performance and reduce the energy consumption that would be wasted on the redundant exhaust *** more information focused on exhaust hood performance,this work suggests more effective strategies for improving indoor air quality and reducing energy consumption in industrial buildings.

关键词： industrial ventilation exhaust hood capture efficiency exhaust rate performance improvement