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Structural evolution of Al–8%Si hypoeutectic alloy by ultrasonic processing

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journal of Materials Science & Technology 2017年第11期33卷 1235-1239页

作者： j.Y.Wang B.j.Wang L.f.Huang Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China

High intensity power ultrasound was respectively introduced into three different solidification stages of Al–8%Si hypoeutectic alloy, including the fully liquid state before nucleation, the nucleation and growth process of primary α（Al） phase and L →（Al）＋（Si） eutectic transformation period. It is found that both the primary α（Al） phase and（Al ＋ Si） eutectic structure were refined by different degrees with various growth morphologies depending on the ultrasonic treatment stage. Based on the experimental results,the cavitation-induced nucleation due to the high undercooling caused by the collapse of tiny cavities was proposed as the major reason for refining the primary α（Al） phase. Meanwhile, obvious eutectic morphological change was observed only when ultrasound was directly introduced in the eutectic transformation stage, in which typical divorced eutectics and（Al ＋ Si） eutectic cells with symmetrical flower shape were formed at the top of the alloy sample. The introduction of ultrasound in each solidification stage also improves the yield strength of Al–8% Si alloy to a diverse extent.

关键词： Solidification Microstructure Metals and alloys Power ultrasound Refinement

Zebrafish as a possible bioindicator of organic pollutants with effects on reproduction in drinking waters

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journal of Environmental Sciences 2015年第7期27卷 254-260页

作者： M.Martínez-Sales f.García-Ximénez f.j.Espinós Aquaculture and Environmental Research Group (ACUMA) Polytechnic University of Valencia

Organic contaminants can be detected at low concentrations in drinking water, raising concerns for human health, particularly in reproduction. In this respect, we attempted to use the zebrafish as a bioindicator to detect the possible presence of these substances in drinking water, aiming to define the most relevant parameters to detect these substances, which particularly affect the development and reproduction of zebrafish. To this end, batches of30 embryos with the chorion intact were cultured in drinking waters from different sources,throughout their full life-cycle up to 5 months, in 20 L tanks. Six replicates were performed in all water groups, with a total of 24 aquariums. Two generations（f0 and f1） were studied and the following parameters were tested： in the f0 generation, survival and abnormality rates evaluated at 5 dpf（days post-fertilization） and at 5 mpf（months post-fertilization）,the onset of spawning and the fertility rate from 3 mpf to 5 mpf, and the sex ratio and underdeveloped specimens at 5 mpf. furthermore, in the f0 offspring（f1）, survival and abnormality rates were evaluated at 5 dpf and the hatching rate at 72 hpf. These results revealed that the hatching rate is the most sensitive parameter to distinguish different levels of effects between waters during the early life stages, whereas the rate of underdeveloped specimens is more suitable at later life stages. Regarding adult reproduction, fertility rate was the most sensitive parameter. The possible reversibility or accumulative nature of such effects will be studied in future work.

关键词： Organic pollutants Bioindicator Development and reproduction parameters Drinking water Zebrafish

Automatic global path generation for large-scale 3D scene exploration

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International journal of Modeling, Simulation, and Scientific Computing 2020年第6期11卷 45-77页

作者： Li Che f.j.Kang Army Aviation Institute Beijing 100123P.R.China School of Marine Science and Technology Northwestern Polytechnical University Xi’an 710072 P.R.China

Large-scale virtual scene exploration is still a challenging task. The novice users caneasily get distracted and disorientated, which results in being lost in space. Assistedcamera control technology is the most effective solution for virtual environment exploration problems which requires viewpoint computation and path planning. In this paper,a novel approach for large-scale virtual scene based on viewpoint scoring is ***, the scene was adaptively divided into several meaningful and easily analyzedsubregions according to the optimal view distance criterion. Second, a novel viewpointscoring method based on visual perception and information entropy fusion was developed for optimal viewpoint determination and greedy N-Best viewpoint selection algorithm was utilized for visual perceptibility calculation. Then evolutionary programmingapproach for the Traveling Salesman problem was applied for intra-subregion and intersubregion exploring path optimization. finally, the Cubic Hermite Curve was introduced to smoothen the inflection point on the exploration path. The experimental resultsdemonstrate that the proposed method can effectively generate an automatic smooth,informative, aesthetic and non-intersecting path, with the characteristics of good exploring comfort, strong immersion and high scene information perception.

关键词： Automatic exploration visual perception viewpoint scoring N-Best viewpoint path optimization large-scale virtual scene

CORROSION PROTECTION Of Al CATHODES IN ZINC ELECTROLYSIS

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Acta Metallurgica Sinica(English Letters) 1999年第3期12卷 221-228页

作者： Lu, f. Van Ooij, W.j. Beijing Inst of Aeronautical Materials Beijing China

A new pretreatment or a coating for Al was developed and tested to protect the Al effectively from corrosion when it was connected to pure zinc at electroplating potential and exposed to an acidic sulfate solution. It was found out that (1) Al alloy purity and electroplating potential have a large effect on galvanic corrosion between Zn-Al couples; (2) BTSE silane pretreatment and polyurethane coating have better performance in corrosion protection, which are evaluated by EIS, salt spray test and immersion test for Al cathodes in Zinc electrolyte; (3) BTSE treatment or BTSE plus polyurethane coating has the best anti-corrosion performance and can protect the Al cathode effectively in zinc electrolysis.

关键词： Aluminum Electrolysis

The song remains the same： juvenile Richardson＇s ground squirrels do not respond differentially to mother＇s or colony member＇s alarm calls

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Current Zoology 2012年第5期58卷 773-780页

作者： james f. HARE Kurtis j. WARKENTIN Department of Biological Sciences University of Manitoba Winnipeg MB Canada R3T 2N2 Department of Zoology Brandon University Brandon MB R7A 6A9

Alarm calls are emitted by Richardson＇s ground squirrels Urocitellus richardsonii in response to avian and terrestrial predators. Conspecifics detecting these calls respond with increased vigilance, promoting predator detection and evasion, but in doing so, lose time from foraging. That loss can be minimized if alarm call recipients discriminate among signalers, and weight their response accordingly. for juvenile ground squirrels, we predicted that the trade-off between foraging and vigilance could be optimized via selective response to alarm calls emitted by their own dam, and/or neighboring colony members over calls broad- cast by less familiar conspecifics. Alarm calls of adult female Richardson＇s ground squirrels were elicited in the field using a predator model and recorded on digital audio tape. free-living focal juveniles were subjected to playbacks of a call of their mother, and on a separate occasion a call from either another adult female from their own colony, or an adult female from another colony. Neither immediate postural responses and escape behavior, nor the duration of vigilance manifested by juveniles differed with exposure to alarm calls of the three adult female signaler types. Thus, juveniles did not respond preferentially to alarm calls emitted by their mothers or colony members, likely reflecting the high cost of ignoring alarm signals where receivers have had limited opportunity to establish past signaler reliability [Current Zoology 58 （5）： 773-780, 2012].

关键词： Alarm Signal Communication Maternal Call Recognition Signal Reliability Ground Squirrel Social Discrimination

Metasomatic Stages and Scapolitization Effects on Chemical Composition of Pasveh Pluton,NW Iran

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journal of Earth Science 2011年第5期22卷 619-631页

作者： S A Mazhari S Amini j Ghalamghash f Bea Department of Geology Payame Noor University Department of Geology Tarbiat Moallem University Geological Survey of Iran Department of Mineralogy and Petrology Fuentenueva CampusUniversity of Granada

Pasveh gabbros are mafic component of a plutonic complex in the northwest Sanandaj- Sirjan Zone. These cumulative rocks are composed of plagioclase and calcic clinopyroxene （Cpx）, which yield unusually high CaO （〉19 wt.%） in whole-rock chemistry. Petrographical and geochemical data suggest that Pasveh gabbros can be divided into two groups： free scapolite and scapolite-bearing gabbros. The second group has higher Na20, K20, and P205 relative to free scapolite ones and is enriched in LIL （large ion lithophile） and HfS （high field strength） elements. Two stages of metasomatism affected the primary composition of mafic rocks. firstly, high temperature reaction caused to invert primary high Ti clinopyroxene to low Ti cUnopyroxene＋high Ti amphibole. This reaction was extensive and included all gabbroic samples. Hydrothermal fluids involved in this process can be derived from dehydration reactions of country rocks or from other magmas incorporated in the formation of Pasveh complex pluton. The second metasomatic stage relates to scapolitization of limited parts of gabbroic rocks. An external saline fluid, which is composed of major NaCI and minor KCI and P205 components, impacted locally on Pasveh gabbros and formed the second metasomatic stage. Possible sources of Na and Cl are primary evaporites or brines, which were present in the host sediments of the gabbros. The carbonate-free nature of these hydrothermal fluids suggests that hydrothermal fluids responsible for the formation of scapolite in Pasveh gabbros are derived from marine evaporitic parentage.

关键词： Iran Sanandaj-Sirjan Zone Pasveh pluton gabbro metasomatism high Ti Cpx low Ti Cpx amphibole scapolite.

Proteasome inhibition-induces endoplasmic reticulum dysfunction and cell death of human cholangiocarcinoma cells

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World journal of Gastroenterology 2007年第6期13卷 851-857页

作者： Yucel Ustundag Steven f Bronk Gregory j Gores Mayo Clinic College of Medicine Rochester MN 55905 United States

AIM: To determine if proteasome inhibition induces apoptosis in human cholangiocarcinoma cells, and if so, to elucidate the cellular mechanisms. METHODS: Studies were performed in the human KMCH, KMBC, and Mz-ChA-1 cholangiocarcinoma, and normal rat cell lines. MG132, a peptide aldehyde, which inhibits the chymotrypsin-like activity of the proteaosome was employed for this study. Apoptosis was assessed morphologically by 4'-6-Diamidino-2-phenylindole (DAPI) nuclear staining and fluorescence microscopy. Mitochondrial membrane potential was examined using a fluorescent unquenching assay. Ultrastructural changes during cell death were examined using transmission electron microscopy (TEM). Caspase 3/7 activity was assessed using an enzymatic-based fluorescent assay. Cytosolic-free calcium concentrations were measured using fura-2 and digitized fluorescent microscopy. RESULTS: MG132, a proteasome inhibitor, induced apoptosis in all the cholangiocarcinoma cell lines examined. In contrast, minimal cytotoxicity was observed in normal rat cholangiocytes. Apoptosis was time-and -concentration-dependent. There was no change in the mitochondrial membrane potential between treated and untreated cells. Ultrastructural examination by transmission electron microscopy displayed the classic features of apoptosis, but in addition, there was also dramatic vacuolization of the endoplasmic reticulum (ER). Unexpectedly, no increase in caspase 3/7 activity was observed in MG132 treated cells, nor did the pancaspase inhibitor, Q-VD-OPh prevent cell death. The protein synthesis inhibitor, cycloheximide, blocked apoptosis induced by proteosome inhibitor indicating that ER dysfunction was dependent upon the formation of new proteins. CONCLUSION: Proteosome inhibition induces ERdysfunction and caspase-independent cell death selectively in human cholangiocarcinoma cells. Proteasome inhibitors warrant evaluation as anticancer agents for the treatment of human cholangiocarcinoma.

关键词： MG132 Cholangiocarcinoma Proteosome Apoptosis Calcium

Some micromechanical models of elastoplastic behaviors of porous geomaterials

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journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 1-17页

作者： W.Q. Shen j.f. Shao Laboratory of Mechanics of Lille University of Lille I Villeneuve d’Ascq 59655 France

Some micromechanics-based constitutive models are presented in this study for porous *** micro-macro mechanical models focus on the effect of porosity and the inclusions on the macroscopic elastoplastic behaviors of porous materials. In order to consider the effect of pores and the compressibility of the matrix, some macroscopic criteria are presented firstly for ductile porous medium having one population of pores with different types of matrix(von Mises, Green type, Misese Schleicher and Druckere Prager). Based on different homogenization techniques, these models are extended to the double porous materials with two populations of pores at different scales and a Druckere Prager solid phase at the microscale. Based on these macroscopic criteria, complete constitutive models are formulated and implemented to describe the overall responses of typical porous geomaterials(sandstone,porous chalk and argillite). Comparisons between the numerical predictions and experimental data with different confining pressures or different mineralogical composites show the capabilities of these micromechanics-based models, which take into account the effects of microstructure on the macroscopic behavior and significantly improve the phenomenological ones.

关键词： Homogenization Porous geomaterials Ductile behavior Double porosity Macroscopic strength Plastic compressibility Druckere Prager solids

Drivability of Large Diameter Steel Cylinders During Hammer-Group Vibratory Installation for the Hong Kong–Zhuhai–Macao Bridge

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Engineering 2023年第1期20卷 180-191页

作者： W.j.Lu B.Li j.f.Hou X.W.Xu H.f.Zou L.M.Zhang Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyKowloonHong Kong 999077China The Hong Kong University of Science and Technology Shenzhen Research Institute Shenzhen 518057China Tianjin Port Engineering Institute Co. Ltd.of CCCC First Harbor Engineering Co.Ltd.Tianjin 300222China Key Laboratory of Port Geotechnical Engineering Ministry of Communications of People’s Republic of ChinaTianjin 300222China CCCC first Harbor Engineering Company Ltd. Tianjin 300461China AECOM Asia Company Limited Hong Kong 999077China

The Hong Kong–Zhuhai–Macao Bridge(HZMB)involved the installation of 120 mega-cylinders with a diameter of 22 m,weights up to 513 t,and penetration depths up to 33 m using an eight-vibratory hammer *** to the lack of engineering experience on the drivability of large-diameter cylinders under multiple vibratory hammers,predicting the penetration rate and time of steel cylinders is an open challenge that has a considerable impact on the construction control of the *** this study,the vibratory penetration of large-diameter steel cylinders in the HZMB is investigated based on geological surveys,field monitoring,and drivability *** vibratory penetration rate,installation accuracy,and dynamic responses of the steel cylinders at both the eastern and western artificial islands are *** dynamic soil resistance has a great influence on the cylinder ***,the current design methods for estimating the vibratory driving soil resistance are proven inaccurate without considering the scale ***,a modified method with a normalized effective area ratio A_(r,eff)is proposed in this study to calculate the vibratory soil resistance for open-ended thin-wall cylinders under unplugged *** the scale effects on the vibratory driving soil resistance,the proposed method leads to closer results to the measured data,providing a reference for future engineering practice.

关键词： Hong Kong-Zhuhai-Macao Bridge Vibratory pile driving Wave equation analysis Large-diameter steel cylinder Artificial island offshore foundati ons