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Preparation and Reaction of Naked Metal Clusters for Catalysis and Genetic Materials

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Chinese Journal of Structural Chemistry 2020年第6期39卷 989-998页

作者： CUI chao-Nan ZHANG Han-Yu luo zhi-Xun PAN Feng Beijing National Laboratory for Molecular Sciences(BNLMS) State Key Laboratory for Stnictural Chemistry of Unstable and Stable SpeciesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Advanced Materials Peking University Shenzhen Graduate SchoolShenzhen 518055China

Metal clusters that contain a small number of atoms usually present unique properties with dramatic dependence on their sizes,geometric structures,and *** studies of naked metal clusters are devoted to develop new catalysts and functional materials of atomic precision,and enable to improve the fundamental theory of structure chemistry and to understand the basic reactions and properties bridging the gap between atoms and bulk *** particular,some interesting superatom clusters have received reasonable research interest indicative of materials gene of *** in this review,we simply summarize the preparation,stability,and reactivity of naked metal clusters with a few examples *** it serves as a modest spur to stimulate more interest of related investigations in this field.

关键词： metal clusters structure chemistry superatom cluster reactivity

Improved delayed detached-eddy simulation of massive separation around triple cylinders

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Acta Mechanica Sinica 2015年第6期31卷 799-816页

作者： zhi-Xiang Xiao Kun-Yu luo School of Aerospace Engineering Tsinghua University

The massively separated flow past triple cylin- ders （TriC） in tandem arrangement is simulated using the improved delayed detached-eddy simulation （IDDES） method based on the shear stress transport （SST） model, coupled with the high order adaptive dissipation scheme. The spacing between adjacent cylinders is sub-critical （1.435D）. IDDES prediction of two cylinders （TC） with the same spacing is compared to experimental data for validation, and the numerical results agree well with the available measurements, except for the asymmetry in the gap region. The flow past TriC is investigated using the same method. Generally, the mean flow quantities past TriC, such as the velocity, pressure, and vorticity, are similar to the corresponding components of TC. However, the pressure fluctuations on the TriC surface are uniformly larger than those on TC. Meanwhile, the instantaneous flows past TriC are much more complex. The periodical blockage in the first gap region is found in the TriC case and leads to the up-and-down movement of shear layer in the second gap region.

关键词： Triple cylinders - Massive separation. IDDES ·Hybrid RANS/LES methods

Study on the tribological properties of metal rolling bearing under lubrication with diketone lubricants

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Science China(Technological Sciences) 2024年第7期67卷 2003-2017页

作者： DU ShaoNan ZHANG ChenHui luo zhi State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Beijing National Laboratory of Molecular Sciences CAS Key Laboratory of Engineering PlasticsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

In this article, 1-(4-ethylphenyl)-nonane-1,3-dione(0206) was prepared by Claisen condensation. By mixing 0206, chelate, and base oil in a ratio of 3.2:4.8:2, a diketone lubricant(PAO=14(20%)) that can achieve superlubricity was prepared and applied to bearing lubrication experiments. The experimental results show that when the bearing was lubricated by base oil, the friction coefficient(COF) and temperature rise decreased with the decrease of the viscosity of PAO. When PAO=14(20%) was used as the lubricant, the COF of the bearing was the lowest(0.001), and the wear morphology was comparable to that of the bearing lubricated with commercial lubricant. Compared with the base oil with the same viscosity, it is found that the COF and temperature rise of the bearing lubricated by PAO=14(20%) were lower under any experimental conditions. And when the amount of lubricant added was 10 μL, the COF of the bearing lubricated by PAO=14(20%) reached a very low value(0.0004).Bearing ball surface analysis identified the formation of diketone adsorption films. Combined with the previous PAO=14(20%)superlubricity mechanism, it was considered that the occurrence of tribochemical reaction and the bearing effect of chelates were the main reasons for the existence of ultra-low friction coefficient and low wear. In addition, when there were polar molecules in the lubricant, they were adsorbed on the metal surface through tribochemical reactions, resulting in many irregular pits on the surface.

关键词： superlubricity diketone chelate tribochemical recations bearing lubrication

Sintering kinetics involving grain growth and densification of Mg-PSZ nanopowders

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Journal of Iron and Steel Research International 2022年第7期29卷 1138-1144页

作者： Yi-ming She Jie-fu Lang Di An chao-wei Si Xu-dong luo zhi-peng Xie Jie-gang You School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina Institute of Advanced Structures Beijing Institute of TechnologyBeijing 100081China State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Sintering kinetics have been found to be effective in judging the evolution of *** using magnesium oxide-partially stabilized zirconia(Mg-PSZ)powder prepared by co-precipitation as raw materials,the evolution of densification and grain growth for Mg-PSZ ceramics were *** results indicated that the densification of samples was mainly controlled by grain boundary diffusion in intermediate sintering *** the sintering process,the grain growth mechanisms included normal grain growth,abnormal grain growth and solid solution drag-controlled grain ***,the apparent activation energy for grain growth of Mg-PSZ ceramics is lower than that of ZrO_(2)–Y_(2)O_(3)ceramics in the solid solution drag-controlled grain grow process,which will cause grain to grow *** sintering kinetics and microstructure of Mg-PSZ ceramics were studied,and the kinetic equation of grain growth at different temperatures was *** results show that the strength difference between Mg-PSZ and yttrium oxide-stabilized zirconia is closely related to the easy grain growth of Mg-PSZ ceramics.

关键词： Magnesium oxide-partially stabilized zirconia Sintering kinetics Grain growth mechanism Densification mechanism Sizing nozzle

Sodium dodecyl sulfate (SDS) as an effective corrosion inhibitor for Mg-8Li-3Al alloy in aqueous NaCl: A combined experimental and theoretical investigation

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Journal of Magnesium and Alloys 2023年第1期11卷 287-300页

作者： Honggun Song zhidong Xu Lahouari Benabou Zheng Yin Hongyu Guan Hong Yan luo chao zhi Hu Xudong Wang Department of Mechanical and Electrical Engineering Nanchang UniversityNanchang330031China UniversitéParis-Saclay UVSQLISV78124Vélizy-VillacoublayFrance Institute for Advanced Study Nanchang UniversityNanchang330031China

The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe force microscopy(SKPFM)and computational *** showed that the corrosion resistance of Mg-8Li-3Al alloy in NaCl solution was effectively improved with *** SEM and SKPFM results confirmed a dense,200 nm-thick SDS-adsorbed layer had formed on the alloy *** separation energy ΔE_(gap) and adsorption energy E_(ads) of SDS on the Mg surface were calculated by density functional theory and molecular dynamics simulations,*** the corrosion inhibition mechanism was hypothesized and described.

关键词： Mg-Li alloy Corrosion Sodium dodecyl sulfate Scanning kelvin probe force microscopy Density functional theory Molecular dynamics

Model test on support scheme for carbonaceous slate tunnel in high geostress zone at high depth

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Journal of Mountain Science 2021年第3期18卷 764-778页

作者： TAO zhi-gang REN Shu-lin LI Gan XU Hao-tian luo Sen-lin HE Man-chao State Key Laboratory for Geomechanics&Deep Underground Engineering China University of Mining and TechnologyBeijing 100083China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing 100083China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

The Muzhailing extra-long highway tunnel and corresponding inclined shafts in Lanzhou,Gansu Province,China passes through structurally complex carbonaceous slate that is under high ground ***-designed and effective support is of high importance for achieving safe and efficient tunnel *** No.2 inclined shaft of Muzhailing Tunnel was taken as the engineering background prototype,for which,a similar model test was conducted to evaluate the effect of highly pretightened constant resistance(NPR,Negative Poisson’s Ratio)anchor cable support provision to the geologically complex carbonaceous slate at different *** schemes were proposed during testing:one scheme was without support and the second was with asymmetric support from highly pre-tightened constant resistance anchor *** speckle displacement analysis system and micro-groundstress sensors were employed to measure the deformation and shear stress distribution of the *** results demonstrated that through the second support scheme,the deformation of the surrounding rock could be effectively ameliorated,while this support scheme was applied on the project site of the No.2 inclined shaft,to explore the rationality of the scheme through field engineering ***-site monitoring indicated that the deformation of the surrounding rock was within the reasonable design range and the problem of severe tunnel deformation was effectively *** research methods and related conclusions can be used as a reference for the treatment of large deformation problems in deep-buried soft rock tunnels.

关键词： Tunnel engineering Support design Carbonaceous slate Similar simulation NPR anchor cable

Multi-objective hydraulic optimization and analysis in a minipump

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Science Bulletin 2015年第17期60卷 1517-1526页

作者： Bin Duan Minqing luo chao Yuan Xiaobing luo School of Energy and Power Engineering Huazhong University of Science and Technology

Minipump is widely used in microfluidics system, active cooling system, etc. But building a high efficiency minipump is still a challenging problem. In this paper, a systematic method was developed to design, characterize and optimize a particular mechanical minipump. The optimization work was conducted to cope with the conflict between pressure head and hydraulic efficiency by an improved back-propagation neural network （BPNN） with the non-dominated sorting genetic algorithm-II （NSGA-II）. The improved BPNN was utilized to predicate hydraulic performance and, moreover, was modified to improve the prediction accuracy. The NSGA-II was processed for minipump multi-objective optimization which is dominated by four impeller dimensions. During hydraulic optimization, the processing feasibility was also taken into consideration. Experiments were conducted to validate the above optimization methods. It was proved that the optimized minipump was improved by about 24 % in pressure head and 4.75 % in hydraulic efficiency compared to the original designed prototype. Meanwhile, the sensitivity test was used to analyze the influence of the four impeller dimensions. It was found that the blade outlet angle β2 and the impeller inlet diameter Do significantly influence the pressure head H and the hydraulic efficiency η, respec- tively. Detailed internal flow fields showed that the optimum model can relieve the impeller wake and improve both the pressure distribution and flow orientation.

关键词： Minipump Optimization Back-propagation neural network Non-dominated sorting genetic algorithm-II

The role of radical prostatectomy and definitive external beam radiotherapy in combined treatment for high-risk prostate cancer:a systematic review and meta-analysis

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Asian Journal of Andrology 2020年第4期22卷 383-389页

作者： Xu Cheng zhi-Hui Wang Mou Peng zhi-chao Huang Lu Yi Yi-Jian Li Lei Yi Wen-zhi luo Jia-Wen Chen Yin-Huai Wang Department of Urology The Second Xiangya Hospital of Central South UniversityChangsha 410011China T.H.Chan School of Public Health Harvard UniversityBostonMA 02115USA

The first-line treatment options for high-risk prostate cancer(PCa)are definitive external beam radiotherapy(EBRT)with or without androgen deprivation therapy(ADT)and radical prostatectomy(RP)with or without adjuvant ***,few randomized trials have compared the survival outcomes of these two *** systematically evaluate the survival outcomes of high-risk PCa patients treated with EBRT-or RP-based therapy,a comprehensive and up-to-date meta-analysis was performed.A systematic online search was conducted for randomized or observational studies that investigated biochemical relapse-free survival(bRFS),cancer-specific survival(CSS),and/or overall survival(OS),in relation to the use of RP or EBRT in patients with high-risk *** summary hazard ratios(HRs)were estimated under the random effects *** identified heterogeneity between studies using Q tests and measured it using I2 *** evaluated publication bias using funnel plots and Egger's regression asymmetry *** studies(including one randomized controlled trial[RCT])of low risk of bias were selected and up to 9504 patients were *** comparing EBRT-based treatment with RP-based treatment,the pooled HRs for bRFS,CSS,and OS were 0.40(95%confidence interval[CI]:0.24–0.67),1.36(95%CI:0.94–1.97),and 1.39(95%CI:1.18–1.62),*** OS for RP-based treatment and better bRFS for EBRT-based treatment have been identified,and there was no significant difference in CSS between the two ***-based treatment is recommended for high-risk PCa patients who value long-term survival,and EBRT-based treatment might be a promising alternative for elderly patients.

关键词： high risk prostatectomy prostatic neoplasms radiotherapy survival

Numerical Study on Heat Transfer Characteristic of the Plate-Fin Microchannel Heat Sink for Water-Based Thermal Management of CPU Chip

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Energy Engineering 2022年第4期119卷 1327-1339页

作者： Jie-chao Chen Rui-Hao luo Wu-zhi Yuan Nan-Long Hong Wen-HaoWang Guangdong Provincial Key Laboratory of Distributed Energy Systems Guangdong Provincial Engineering Research Center of Distributed Energy SystemsDongguan University of TechnologyDongguan523808China

For effective water-based thermal management of high heat generating CPU chip,a series of numerical simulation has been conducted to study the effects of heat flux,fin height and flow rate on convective thermal performance of the plate-fin microchannel heat *** characteristics of heat transfer and flow resistance have been quantificationally discussed and JF factor is employed to evaluate the comprehensive efficiency of convective heat transfer of microchannel heat *** show that the increase in fin height and flow rate of cooling water is helpful to decrease the maximum temperature of CPU *** flow rate and heat flux and short fin height are benefit to improve Nusselt number Nu,but they lead to large resistance coefficient fRe *** of JF factor shows that the microchannel with short fins shows better convective thermal performance when the thermal power of the CPU chip is *** fins should be heightened when the CPU is operating at higher thermal *** employment of JF factor in the present work shows its pertinence and convenience in the application of design of microchannel heat sink.

关键词： JF factor convective thermal performance numerical simulation thermal management of CPU