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An overview of flow field computational methods for hydrodynamic noise prediction

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Journal of Hydrodynamics 2022年第6期34卷 994-1005页

作者： Wei-wen Zhao Zhi Pan Lian-jie Yu De-cheng Wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Wuhan Second Ship Design and Research Institute Wuhan430205China

Recently,the hydrodynamic noise is becoming a research hotspot because it not only affects the concealment and comfort of ships,but also affects the living condition of underwater mammals.Accurate prediction of hydrodynamic noise requires that the detailed flow field has been simulated temporally and spatially with high fidelity method.In this paper,we introduce the current issues and challenges for the prediction of hydrodynamic noise,and provide an overview to several detailed flow field simulation methods which aim to resolve these issues.The overview could point the future directions for hydrodynamic noise prediction.

关键词： Hydrodynamic noise turbulent fluctuation wall-bounded flow two-phase flow noise reduction

4-Dimethylaminopyridine-Boryl Radical Promoted Monodefluorinative Alkylation of 3,3-Difluorooxindoles

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Chinese Journal of Chemistry 2022年第5期40卷 577-581页

作者： Tesfaye Tebeka Simur Fentahun Wondu Dagnaw You-jie yu Feng-lian Zhang Yi-Feng Wang Hefei National Laboratory for Physical at the Microscale Department of ChemistryUniversity of Science and Technology of China96 Jinzhai RoadHefeiAnhui230026 China

A selective monodefluorinative alkylation of 3,3-difluorooxindoles is achieved.The reaction starts by the attack of a 4-dimethylaminopyrine-boryl radical to the carbonyl oxygen atom of 3,3-difluorooxindoles,followed by a spin-center shift to generate radical intermediates with the elimination of a fluoride anion.The subsequent radical addition to alkenes affords a range of 3-alkyl-fluorooxindoles products.The strategy offers access to C-3 functionalized oxindoles with wide substrate scope and tolerates a wide range of functional groups.

关键词： Radical reactions Alkylation I Fluorine Spin-center shift Defluorination

C–F bond functionalizations of trifluoromethyl groups via radical intermediates

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Chinese Chemical Letters 2022年第3期33卷 1193-1198页

作者： Tesfaye Tebeka Simur Tian Ye You-jie yu Feng-lian Zhang Yi-Feng Wang Department of Chemistry University of Science and Technology of ChinaHefei 230026China

Selective functionalization of C-F bonds in trifluoromethyl groups has recently received a growing interest, as it offers atom- and step-economic pathways to access highly valuable mono- and difluoroalkyl-substituted organic molecules using simple and inexpensive trifluoromethyl sources as the starting materials. In this regard, impressive progress has been made on the defluorinative functionalization reactions that proceed via radical intermediates. Nevertheless, it is still a great challenge to precisely control the defluorination process, due to the continuous decrease of the C-F bond strength after the replacement of one or two fluorine atoms with various functionalities. This review article is aimed to provide a brief overview of recently reported methods used to functionalize C-F bonds of CF_(3) groups via radical intermediates. An emphasis is placed on the discussion of mechanistic aspects and synthetic applications.

关键词： C–F bond functionalizations Radical intermediates Trifluoromethyl groups Difluorinated compounds Monofluorinated compounds

Tracking the Process of Domino Ring-Opening and Coupling of Fused Imidazole and Direct Observation of Peroxide Intermediates

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Chinese Journal of Chemistry 2023年第17期41卷 2089-2094页

作者： yu Wang Mei-lian Luo Jin Cai Tao Zhang yu-jie Wu Ming-Da Song Bin Lu Ming-Hua Zeng Organic Functional Molecules College of Chemistry&Chemical EngineeringHubei UniversityWuhanHubei 430062China State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources(Ministry of Education of China)Collaborative Innovation Centerfor Guangxi Ethnic MedicineSchoolof Chemistryand Pharmaceutical SciencesGuangxi Normal UniversityGuilinGuangxi 541004China College of Chemistry and Chemical Engineering Jinggangshan UniversityJi'anJiangxi 343000China

Comprehensive Summary,A domino ring-opening and coupling of imidazolyl annulated heterocycles 1(1a:4-methyl-1-(1-methyl-1H-benzo[d]imidazol-2-yl)-4H-benzo[d]imidazo[1,5-a]imidazole,1b:1-(1,5-dimethyl-1H-benzo[d]imidazol-2-yl)-4,7-dimethyl-4H-benzo[d]imidazo[1,5-a]imidazole)with dioxygen was developed at solvothermal condition,leading to conjugated 1,2-diamidoalkenes derivatives 2((E)-ArCONHArC=CArNHCOAr(Ar:1-methyl-1H-benzo[d]imidazolyl(2a),1,5-dimethyl-1H-benzo[d]imidazolyl(2b)))as single crystals directly.The reaction process was tracked by electrospray ionization mass spectrometry(ESI-HRMS)and a series of reaction intermediates are detected.^(18)O_(2) labeling experiment verified the source of oxygen in 2.Combining evidence from control experiments,nuclear magnetic resonance(NMR)tracking,and crystallography,a seven-step reaction pathway involving oxygen addition,ring opening,Friedel-Crafts alkylation,oxidation,and dehydration was proposed and further supported by DFT calculation.

关键词： Domino reaction Process tracking Ring-opening Mass spectrometry Isotopes C-C coupling Density functional calculations

Meta-analysis of the effectiveness and safety of vedolizumab for ulcerative colitis

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World Journal of Gastroenterology 2015年第20期21卷 6352-6360页

作者： yu Jin Yan Lin lian-jie Lin Chang-Qing Zheng Department of Gastroenterology Shengjing Hospital of China Medical University

AIM: To conduct a meta-analysis examining the effectiveness and safety of vedolizumab for the treatment of ulcerative colitis(UC).METHODS: A search was conducted of MEDLINE, Cochrane, EMBASE, and Google Scholar on July 31, 2013. Inclusion criteria were:(1) Randomized controlled trial(RCT);(2) Patients treated for UC; and(3) Intervention was vedolizumab. The following information/data were extracted from studies that met the inclusion criteria: the name of the first author, year of publication, study design, patient demographic information, response rate, remission rate, and adverse events. The primary outcome was clinical response rate, and the secondary outcomes were clinical remission rate and serious adverse events. Odds ratio(OR) with 95%CI were calculated for each outcome. RESULTS: Of 224 studies initially identified, three RCTs examining the use of vedolizumab meeting the inclusion criteria were included in the meta-analysis. All studies examined the use of vedolizumab at dosages ranging from 0.5 to 10 mg/kg body weight(one study used a standard dose of 300 mg). The follow-up periods were approximately 6 wk. The total number of patients in the intervention groups was 901, and in the control groups was 221. The mean age of the patients was approximately 41 years, and approximately half were males. The follow-up periods ranged from 43 d to 6 wk. The clinical response and remission rates were significantly higher for patients who received vedolizumab as compared to control patients(clinical response: OR = 2.69; 95%CI: 1.94-3.74, P < 0.001 and remission rate: OR = 2.72; 95%CI: 1.76-4.19, P < 0.001). Serious adverse events were not higher in patients that received vedolizumab.CONCLUSION: This analysis supports the use of vedolizumab for the treatment of UC.

关键词： Inflammatory bowel disease Ulcerativecolitis Vedolizumab MLN-002 Meta-analysis

Clarifying effect of welding conditions on microstructure and mechanical properties of friction stir spot-welded DH590 automotive high-strength steel plates

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Journal of Iron and Steel Research(International) 2021年第2期28卷 232-243页

作者： Ya-peng Zhao lian-feng Chen Shi-jie Zhu yu-feng Sun Shao-kang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001HenanChina Henan Key Laboratory of Advanced Magnesium Alloys Zhengzhou UniversityZhengzhou 450001HenanChina Beijing Shougang Co. Ltd.Beijing 100041China

Friction stir spot welding was successfully applied to the 1.2-mm-thick DH590 dual-phase steel plates by using a polycrystalline cubic boron nitride rotating tool.During welding,the rotation speed ranged from 600 to 1000 r/min and the penetration depth ranged from 0.1 to 0.3 mm.In the spot joints,the size of the stir zone increased with the increase in rotation speed as well as the penetration depth of the tool.Comparing with the banded ferrite and martensite structure of the base metal,a mixed microstructure of ferrite and tempered martensite,refined bainite structure and coarse martensite structure were found in the heat-affected zone,thermomechanically affected zone and stir zone of the joints,respectively.Two kinds of interfacial shapes were formed between the upper and lower steel plates,and the formation of the bonded interface was dominated mainly by the penetration depth of the rotating tool rather than the rotation speed.It was revealed that the joints with straight interfaces showed higher shear tensile loads comparing with those with hook-like interfaces.Shear tensile tests showed that the maximum shear tensile load reached about 15.56 kN when the rotation speed and penetration depth were set as 800 r/min and 0.3 mm,respectively.The specimen was fractured through plug failure mode with a total elongation of about 5.6 mm.

关键词： Friction stir spot welding DH590 dual-phase steel Microstructure Joint strength Microhardness

Towards a more flexible representation of water stress effects in the nonlinear Jarvis model

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Journal of Integrative Agriculture 2017年第1期16卷 210-220页

作者： yu lian-yu CAI Huan-jie ZHENG Zhe LI Zhi-jun WANG Jian Key Laboratory of Agricultural Soil and Water Engineering in Arid Area Ministry of Education/Northwest A&F UniversityYangling 712100P.R.China Institute of Water Saving Agriculture in Arid Regions of China(IWSA) Northwest A&F UniversityYangling 712100P.R.China

To better interpret summer maize stomatal conductance （gs） variation under conditions of changing water status at different growth stages, three water stress indicators, soil water content （SWC）, leaf-air temperature difference （AT） and leaf level water stress index （CWSIL） were employed in Jarvis model, which were Js, JT and Jc models respectively. Measurements of gs were conducted in a summer maize field experiment during the year 2012-2013. In the insufficient irrigation exper- iment, three levels of irrigation amount were applied at four different growth stages of summer maize. We constructed three scenarios to evaluate the performance of the three water stress indicators for estimating maize gs in a modified Jarvis model. Results showed that JT and Jc models had better simulation accuracy than the Js model, especially at the late growth stage （Scenario 1） or considering the plant recovery compensation effects （Scenario 2）. Scenario 3 indicated that the more environmental factors were adopted, the better prediction performance would be for Js model. While for JT model, two environmental factors （photosynthesis active radiation （PAR）, and vapor pressure deficit （VPD）） seemed good enough to obtain a reliable simulation. When there were insufficient environmental data, CWSI, would be the best option. This study can be useful to understand the response of plant stomatal to changing water conditions and will further facilitate the application of the Jarvis model in various environments.

关键词： summer maize stomatal conductance water status recovery compensation water stress indicators Jarvis model

Intraoperative Transesophageal Echocardiography in the Operation of Ebstein＇s Anomaly： A Retrospective Study

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Chinese Medical Journal 2017年第13期130卷 1540-1543页

作者： Xiu-jie Tang Min Bao He Zhao lian-Yi Wang Qing-yu Wu Heart Center First Hospital of Tsinghua University Beijing 100016 China Department of Cardiovascular Capital Institute of Pediatrics Beijing 100020 China

Background： Ebstein＇s anomaly （EA） has various spectrums in clinical and anatomic features. This study aimed to report the experience of two-dimensional intraoperative transesophageal echocardiography （2D-ITEE） during the EA surgery and to analyze the characteristics of the tricuspid valve （TV） by comparing the data from 2D-ITEE with the results from the surgery. Methods： 2D-ITEE data of 164 patients with EA who were operated in the First Hospital of Tsinghua University between July 2004 and April 2014 were retrospectively analyzed in this study. 2D-ITEE was applied in all patients. Downward displacement distances were measured, and the numbers of downward displacement or absent leaflets were compared with that of the surgery and with that of the two-dimensional-transthoracic echocardiogram （2D-TTE）. Data comparison was peribrmed using the Chi-square test. Results： The anterior leaflet partial or total downward displacement was 37.76 ±17.50 mm in 54 cases, absent in one patient; septal leaflet downward displacement was 29.07 ± 12.34 mm in 134 cases, absent in 17 cases; and posterior leaflet downward displacement was 43.18 ± 19.16 mm in 115 cases, absent in 34 cases. Statistically, there was no significant difference between the results from 2D-ITEE and that of 2D-TTE. The consistency rates of 2D-ITEE with operation for septal and posterior leaflets were 93.2% and 96.1%, respectively, while the rate for anterior was only 40.1%o, which was significantly different. Color Doppler flow image showed severe regurgitation in 150 cases and moderate in 14 cases. After surgical correction, moderate regurgitation of TV was found in 58 cases with 2D-ITEE, repair was performed again until the effect was satisfied. No complication occurred relating to the use of 2D-ITEE. Conclusions： 2D-ITEE could help diagnose anterior leaflet, evaluate the effect of TV repair, increase operational success rate, and reduce complication.

关键词： Ebstein＇s Anomaly Echocardiography Two-dimensional-transesophageal Echocardiography

Recent Progress in Carbon-based Materials of Non-Noble Metal Catalysts for ORR in Acidic Environment

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Acta Metallurgica Sinica(English Letters) 2021年第7期34卷 885-899页

作者： jie lian Jin-yu Zhao Xiao-Min Wang College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Shanxi Key Laboratory of New Energy Materials and Devices Taiyuan University of TechnologyTaiyuan 030024China

Proton exchange membrane fuel cell(PEMFC)has important implications for the success of clean transportation in the future.One of the key factors affecting the cost and performance of PEMFC is the cathode electrocatalyst for the oxygen reduction reaction(ORR)to overcome sluggish kinetics and instability in an acidic environment.As an essential component of the electrocatalyst,the support material largely determines the activity,mass transfer,charge transfer,and durability of the electrocatalyst.Thereby,the support material plays a critical role in the overall performance of the electrocatalyst.Carbonbased materials are widely used as electrocatalyst supports because of their high porosity,conductivity,chemical stability,and tunable morphology.Recently,some new carbon-based materials with excellent structure have been introduced,such as carbon nanotubes,carbon nanowires,graphene,metal-organic framework(MOF)-derived carbon,and biomass-derived carbon materials.Combined with a variety of strategies,such as controllable construction of porous structures and surface defects,proper doping heteroatoms,the ingenious design of model electrocatalysts,and predictive theoretical calculation,a new reliable path was provided for further improving the performance of electrocatalysts and exploring the catalytic mechanism.Based on the topic of carbon-based materials for ORR in acidic medium,this review summarizes the up-to-date progress and breakthroughs,highlights the factors affecting the catalytic activity and stability of ORR electrocatalysts in acids,and discusses their future application and development.

关键词： Carbon-based materials Non-noble metal electrocatalysts Acidic environment Oxygen reduction reaction Proton exchange membrane fuel cell