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Formation of free-surface vortex and vortex suppression by rotating stopper-rod at end of tundish casting

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Journal of Iron and Steel Research(International) 2024年第5期31卷 1104-1116页

作者： qing Fang Peng Zhao Hua Zhang Wen-hao Zhou Gang Yu jia-hui Wang Hong-wei Ni The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina Hunan Valin Xiangtan Iron and Steel Co. Ltd.Xiangtan411101HunanChina Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan430081HubeiChina

A rotating stopper-rod technique was proposed to suppress the formation of free-surface vortex in the *** large eddy simulation model coupled with volume of fluid model was developed to study the steel–slag–gas three-phase flow *** critical slag entrapment height of the free-surface vortex and mass of residual steel were predicted at different rotating speeds(30,60,90 and 120 r/min)of the rotating *** numerical model was verified by water model *** results showed that by rotating the stopper-rod in the opposite direction of the vortex above the submerged entry nozzle,the formation of vortex can be effectively disturbed and the critical height of the free-surface vortex can be *** for the 2nd strand,when the rotating speeds are 30,60,90 and 120 r/min,the critical height of the free-surface vortex above the 2nd strand is 7.3,4.7,6.3 and 7.4 cm,respectively.A reasonable rotating speed should be 60 r/min,which can reduce about 2 tons of residual *** rotating speeds just can reduce about 1.6 tons of residual steel.

关键词： Tundish Free-surface vortex Stopper-rod Numerical simulation Multiphase flow

Towards hydrometeorological thresholds of reservoir-induced landslide from subsurface strain observations

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Science China(Technological Sciences) 2024年第6期67卷 1907-1922页

作者： YE xiao ZHU HongHu WANG jia ZHENG WanJi ZHANG Wei SCHENATO Luca PASUTO Alessandro CATANI Filippo School of Earth Sciences and Engineering Nanjing UniversityNanjing210023China Department of Geosciences University of PadovaPadova35131Italy School of Geosciences and Info-Physics Central South UniversityChangsha410083China Department of Information Engineering University of PadovaPadova35131Italy National Research Council-Research Institute for Geo-Hydrological Protection(CNR-IRPI) Padova35127Italy

Synergistic multi-factor early warning of large-scale landslides is a crucial component of geohazard prevention and mitigation efforts in reservoir *** forecasting and early warning based on surface displacements have been widely ***,the lack of direct subsurface real-time observations limits our ability to predict critical hydrometeorological conditions that trigger landslide *** this paper,we leverage subsurface strain data measured by high-resolution fiber optic sensing nerves that were installed in a giant reservoir landslide in the Three Gorges Reservoir(TGR)region,China,spanning a whole hydrologic year since February *** spatiotemporal strain profile has preliminarily identified the slip zones and potential drivers,indicating that high-intensity short-duration rainstorms controlled the landslide kinematics from an observation *** the time lag effect,we reexamined and quantified potential controls of accelerated movements using a data-driven approach,which reveals immediate response of landslide deformation to extreme rainfall with a zero-day *** identify critical hydrometeorological rules in accelerated movements,accounting for the dual effect of rainfall and reservoir water level variations,we thus construct a landslide prediction model that relies upon the boosting decision tree(BDT)algorithm using a dataset comprising daily rainfall,rainfall intensity,reservoir water level,water level fluctuations,and slip zone strain time *** results indicate that landslide acceleration is most likely to occur under the conditions of mid-low water levels(i.e.,57.9 mm and rainfall intensity>24.4 mm/h).Moreover,this prediction model allows us to update hydrometeorological thresholds by incorporating the latest monitoring *** on the shoulder of this landslide case,our study informs a practical and reliable path

关键词： slow-moving landslide fiber-optic monitoring subsurface strain hydrometeorological threshold extreme weather

Evolution of Cenozoic sedimentary architecture in Central and Southern South China Sea basins

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Journal of Palaeogeography 2024年第1期13卷 35-53页

作者： Wu Tang xiao-Jun Xie Yi-Bo Wang Lian-Qiao Xiong jia Guo Xin Li China National Offshore Oil Corporation Research Institute Beijing 100028China

The Central and Southern South China Sea(CSSCS) has a complex tectonic dynamic background and abundant oil and gas resources, which has always been a hot topic of academic and industrial ***, systematic analyses are still lacking regarding its sediment filling structure and evolution, mostly due to limited borehole penetration and poor quality of seismic reflection data for deeply buried sequences. No consensus has been reached yet on the sedimentary infilling processes, which impeded the reconstruction of the palaeogeography of Southeast Asia and the oil-and-gas exploration undertakings. Here, we illustrate the Cenozoic sedimentary evolution of the CSSCS region by synthesizing relevant data from previous literature and our own observations and displaying the evolution of depositional systems in sequential reconstructions. Besides, the controlling factors of preferred sedimentary scenarios in the CSSCS incorporate the latest interpretations of the spreading of South China Sea(SCS) as well as the demise of the hypothetical Proto-South China Sea(PSCS). The results show that there are three types of sedimentary basins in the CSSCS(foreland,strike-slip, and rift basins) with different sedimentary filling structures. The foreland basins formed a depositional pattern of ‘transition from deep water to shallow water environments', dominated by deep-water depositional systems which were formed before the Early Oligocene with submarine fans developed. Later,the foreland basins were gradually dominated by shallow-water depositional systems with deltas and shallow marine facies. The strike-slip basins showed the depositional architecture of ‘transition from lake to marine environments', i.e. the basins were dominated by lacustrine deposits during the Eocene and evolved into the marine depositional environment since Oligocene with delta developed in the western part of the basin. The depositional evolution of rift basins illustrated the characteristics of 'transiti

关键词： Central and Southern South China Sea Sedimentary filling Main controlling factors Proto-South China Sea South China Sea

Visible-Light-Driven Four-Component Radical Relay Aminocarbonylation of Unactivated Alkenes

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Chinese Journal of Chemistry 2024年第9期42卷 990-996页

作者： Bin Lu Feng-Shuo Bao Zi-Wei He Wen-Jing xiao jia-Rong Chen Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction College of ChemistryCentralChina Normal University152 Luoyu RoadWuhanHubei 430079China Wuhan Institute of Photochemistry and Technology 7North Bingang RoadWuhanHubei 430083China Key Laboratory of Organo-Pharmaceutical Chemistry of jiangxi Province Gannan Normal UniversityGanzhouJiangxi 341000China

Catalytic four-component radical carbonylation of unactivated alkenes has recently been recognized as a robust protocol for rapid construction of various structurally diverse carbonyl *** the significance of fluorine-containing groups,this reaction class has been extensively applied to assembly of a variety of perfluoroalkyl carboxylic acid derivatives by transition metal ***,we report a visible-light-driven radical relay 1,2-perfluoroalkylation aminocarbonylation of unactivated alkenes using CO gas as carbonyl source and 4CzIPN as organic photocatalyst.A wide range of alkenes and amines were well tolerated,providing the valuableβ-perfluoroalkylated amides with generally good yields and high chemoselectivity.

关键词： Visible light Photoredox catalysis Radical aminocarbonylation Multicomponent reaction Carbon monoxide Unactivated alkenes AmidesIReactionmechanisms

Therapeutic potential of urine-derived stem cells in renal regeneration following acute kidney injury:A comparative analysis with mesenchymal stem cells

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World Journal of Stem Cells 2024年第5期16卷 525-537页

作者： Fang Li Bin Zhao Lei Zhang Guo-qing Chen Li Zhu xiao-Ling Feng Meng-jia Gong Cheng-Chen Hu Yuan-Yuan Zhang Ming Li Yong-Qiang Liu Department of General Surgery Chongqing General HospitalChongqing 401147China Department of Pediatric Research Institute Children’s Hospital of Chongqing Medical UniversityChongqing 401147China

BACKGROUND Acute kidney injury(AKI)is a common clinical syndrome with high morbidity and mortality *** use of pluripotent stem cells holds great promise for the treatment of ***-derived stem cells(USCs)are a novel and versatile cell source in cell-based therapy and regenerative medicine that provide advantages of a noninvasive,simple,and low-cost approach and are induced with high multidifferentiation *** these cells could serve as a potential stem cell source for the treatment of AKI has not been *** Stem cell markers with multidifferentiation potential were isolated from human amniotic *** severe combined immune deficiency(SCID)mice models were induced by means of an intramuscular injection with *** isolated from human-voided urine were administered via tail *** functional changes in the kidney were assessed by the levels of blood urea nitrogen and serum *** histologic changes were evaluated by hematoxylin and eosin staining and transferase dUTP nick-end labeling ***,we compared the regenerative potential of USCs with bone marrow-derived mesenchymal stem cells(MSCs).RESULTS Treatment with USCs significantly alleviated histological destruction and functional *** renal function was rapidly restored after intravenous injection of 5×105 human USCs into SCID mice with glycerol-induced AKI compared with injection of *** from secretion assays conducted in vitro demonstrated that both stem cell varieties released a wide array of cytokines and growth *** suggests that a mixture of various mediators closely interacts with their biochemical *** types of stem cells showed enhanced tubular cell prolif-eration and decreased tubular cell apoptosis,although USC treatment was not more effective than MSC *** found that USC therapy significantly improved renal function and histological damage,inhibited inflammation and apoptosis processes in the kid

关键词： Urine-derived stem cells Regenerative medicine Acute kidney injury Renal function recovery Cell therapy

Cognitive Training in Older Adults with Mild Cognitive Impairment

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Biomedical and Environmental Sciences 2016年第5期29卷 356-364页

作者： LIU Xin Yan LI Li xiao jia qing HE Chang Zhi LYU Xiu Lin GAO Lei YANG xiao Wei CUI Xin Gang FAN Li Hua College of Public Health Harbin Medical University Harbin 150086 Heilongjiang China Heilongjiang Provincial Center for Disease Control and Prevention Harbin 150040 Heilongjiang China College of Management for the postgraduate Harbin Medical University Harbin 150086 Heilongjiang China Heilongjiang Provincial Hospital Harbin 150040 Heilongjiang China Department of Public Health Mudanjiang Medical College Mudanjiang 157000 Heilongjiang China

Objective We investigated the feasibility and efficacy of cognitive training for older adults in rura settings and with low education levels, who have mild cognitive impairment （MCl）. Methods Forty-five older adults （ages 〉65 years） with MCI were assigned to treatment or control groups, at a 2：1 ratio. Cognitive training occurred in the treatment group for 2 months. The cognitive abilities of the participants were assessed at pre-training, metaphase, and post-training time points, using the Mini-Mental State Examination （MMSE）, Montreal Cognitive Assessment （MoCA）, Loewenstein Occupational Therapy Cognitive Assessment （LOTCA）, and Hamilton Depression Scale （HAM-D）. Results Following training, cognitive abilities improved in the treatment group, based on the total scores of all 4 measures, as well as specifically on the MoCA and LOTCA. There were differences in the main effects of group and time point on some subscales, but these differences had little, if any, effect on the overall analyses. Conclusion The present study demonstrated that cognitive training has beneficial effects on attention, language, orientation, visual perception, organization of visual movement, and logical questioning in patients with MCI. Furthermore, the observed effects are long-term changes.

关键词： Older adults Rural Mild cognitive impairment Cognitive training Efficacy

Ultrasound-guided paravertebral nerve block anesthesia for percutaneous endoscopic laser unroofing treatment of symptomatic simple renal cysts—An innovative ambulatory surgery mode

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Asian Journal of Urology 2024年第1期11卷 65-71页

作者： jia Hu Yuan Zhang Yong Liu xiao Yu Shaogang Wang Department of Urology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina Department of Anesthesiology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina

Objective:This study was designed to evaluate the feasibility,efficacy,and safety of percutaneous ureteroscopy laser unroofing as an ambulatory surgery for symptomatic simple renal cysts under multilevel paravertebral nerve block ***:From December 2015 to September 2017,33 simple renal cyst patients who had surgical indications were *** ultrasound guidance,the T10/T11,T11/T12,and T12/L1 paravertebral spaces were identified,and 7-10 mL 0.5%ropivacaine was injected at each *** a puncture needle was placed inside the cyst cavity under ultrasonic monitoring.A guidewire was introduced followed by sequential dilation up to 28/30 *** extra parenchymal portion of the cyst wall was dissociated and incised using a thulium laser,and a pathological examination was ***:Sensory loss to pinprick from T8 to L1 and sensory loss to ice from T6 to L2 were observed in all *** of the patients complained of pain during *** serious complications occurred *** the surgery,all patients recovered their lower limb muscle strength quickly,got out of bed,resumed oral feeding,and left the hospital within 24 h of *** pathologic diagnosis of all cyst walls was a simple renal *** mean follow-up was 35.8 *** the end of follow-up,the cyst units were reduced in size by more than 50%compared to the preoperative size,and no patient experienced a ***:Multi-level paravertebral nerve block for percutaneous ureteroscopy laser unroofing as an ambulatory surgery mode is feasible,safe,and effective for the treatment of simple renal cysts in selected patients.

关键词： Paravertebralnerve blockanesthesia Percutaneous puncture Simplerenalcyst Unroofing Ambulatorysurgery

Wear-resistant CoCrNi multi-principal element alloy at cryogenic temperature

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Science Bulletin 2024年第2期69卷 227-236页

作者： Yue Ren qing Zhou Dongpeng Hua Zhuobin Huang Yulong Li Qian jia Peter Gumbsch Christian Greiner Haifeng Wang Weimin Liu State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Institute for Applied Materials Karlsruhe Institute of TechnologyKarlsruhe 76131Germany IAM-ZM MicroTribology CenterμTC Karlsruhe Institute of TechnologyKarlsruhe 76131Germany Fraunhofer IWM Freiburg 79108Germany State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Traditional high strength engineering alloys suffer from serious surface brittleness and inferior wear performance when servicing under sliding contact at cryogenic ***,we report that the recently emerging CoCrNi multi-principal element alloy defies this trend and presents dramatically enhanced wear resistance when temperature decreases from 273 to 153 K,surpassing those of cryogenic austenitic *** temperature-dependent structure characteristics and deformation mechanisms influencing the cryogenic wear resistance of CoCrNi are clarified through microscopic observation and atomistic *** is found that sliding-induced subsurface structures show distinct scenarios at different deformation *** cryogenic condition,significant grain refinement and a deep plastic zone give rise to an extended microstructural gradient below the surface,which can accommodate massive sliding deformation,in direct contrast to the strain localization and delamination at 273 ***,the temperature-dependent cryogenic deformation mechanisms(stacking fault networks and phase transformation)also provide additional strengthening and toughening of the subsurface *** features make the CoCrNi alloy particularly wear resistant at cryogenic conditions and an excellent candidate for safety–critical applications.

关键词： Multi-principal element alloy Cryogenic temperature Wear CoCrNi

Degradation behaviors of Nabumetone and its metabolite during UV/monochloramine process:Experimental and theoretical study

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Journal of Environmental Sciences 2024年第8期142卷 103-114页

作者： Xiang Tu Yunsong Bai qing Fu Sheng Chang Kunfeng Zhang Yang Pan Ruiyang xiao Yifu Fu Qi Zhang State Key Laboratory of Environmental Criteria and Risk Assessment State Environmental Protection Key Laboratory of Drinking Water Source ProtectionResearch Centre of Lake EnvironmentNational Engineering Laboratory for Lake Pollution Control and Ecological RestorationChinese Research Academy of Environmental SciencesBeijing 100012China School of Environmental Science and Engineering Suzhou University of Science and TechnologySuzhou 215009China Institute of Environmental Engineering School of Metallurgy and EnvironmentCentral South UniversityChangsha 410083China School of Forestry Northeast Forestry UniversityHarbin 150040China

This study investigated degradation behaviors of a nonsteroidal anti-inflammatory drug Nabumetone(NMT)and its major metabolite 6-methoxy-2-naphthylacetic acid(MNA)in the coupling process of ultraviolet and monochloramine(UV/NH2Cl).The second-order rate constants of the contaminants reacting with reactive radicals(HO·,Cl·,Cl_(2)·-,and CO_(3)·^(-))were determined by laser flash photolysis ***·and Cl·contributed predominantly with 52.3%and 21.7%for NMT degradation and 60.8%and 22.3%for MNA *** presence of chlorides retarded the degradation of NMT,while promoted the destruction of MNA,which was ascribed to the photosensitization effects of MNA under UV *** functional theory(DFT)calculations revealed that radical adduct formation(RAF)was dominant pathway for both HO·and Cl·reacting with the contaminants,and hydrogen atom transfer(HAT)preferred to occur on side chains of NMT and *** reacted with NO_(2)·through single electron transfer(SET)with the second-order rate constant calculated to be 5.35×10^(7)(mol/L)^(-1)sec^(-1),and the contribution of NO_(2)·was predicted to be 13.0%of the total rate constant of NMT in pure water,which indicated that NO_(2)·played a nonnegligible role in the degradation of *** acute toxicity and developmental toxicity of NMT were enhanced after UV/NH_(2)Cl treatment,while those of MNA were *** transformation products of both NMT and MNA exhibited higher mutagenicity than their parent *** study provides a deep understanding of the mechanism of radical degradation of NMT and MNA in the treatment of UV/NH2Cl.

关键词： UV/NH_(2)Cl Reactive species Degradation kinetics Reaction mechanism Degradation products