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Kinetic modeling of high-temperature oxidation of pure Mg

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Journal of Magnesium and Alloys 2020年第3期8卷 819-831页

作者： sa Ma Fangzhou Xing na Ta Lijun Zhang State Key laboratory of Powder Metallurgy Central South UniversityChangshaHunan 410083P.R.China Max-Planck-Institut fiir Eisenforschung GmbH Max-Planck-Straβe 140237DusseldorfGermany

A variety of experimental tracer diffusivities of Mg and O in magnesium oxide available in the literature were first *** mobilities including bulk and short-circuit diffusion of Mg and O were then obtained by means of the CALPHAD(Calculation of Phase Diagram)***,the diffusion-controlled kinetic model of oxidation in a gas-MgO-Mg environment was developed based on the moving boundary model and Fick's law,coupling with the modified thermodynamic description of MgO.A mathematical expression for parabolic rate constant kp of the oxide scale was derived for magnesia and correlated with the thermodynamic and diffusion kinetic *** evaluated kp results were in line with the experimental ***,the oxidation process of pure magnesium at 673 K was model-predicted,and the predicted evolution of the oxide thicknesses agreed very well with the experimental *** was indicated that the grain boundaries diffusion of magnesium cations predominated the high temperature oxidation process.

关键词： MgO Diffusion Oxidation Atomic mobility CALPHAD Wagner's model

Effect of Alkali Stress on Soluble Sugar, Antioxidant Enzymes and Yield of Oat

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Journal of Integrative Agriculture 2013年第8期12卷 1441-1449页

作者： BAI Jian-hui LIU Jing-hui ZHANG na YANG Jun-heng sa Ru-la WU lan Science Innovation Team of Oat Inner Mongolia Agricultural University College of Foreign languages Inner Mongolia Agricultural University

Alkali stress can cause severe crop damage and reduce production. However, physiological processes involved in alkali stress in oat seedlings are not well understood. In this study, physiological responses and yield of oat to alkali stress were studied using the alkali-tolerant oat genotype Vao-9 and the alkali-sensitive oat genotype Baiyan 5. The results were：（i） low concentrations of alkali stress （25 and 50 mmol L^-1） significantly reduced the yield and grain weight while increased the oat grain number per spike. A negative correlation between yield and malondialdehyde （MDA） content at the jointing and grain filling stages and positive correlations between yield on one hand and superoxide dismutase （SOD）, and peroxidase （POD） activities on the other at the jointing stage were observed. There was a positive correlation between MDA and soluble sugar at the grain filling stage; （ii） soluble sugar content was increased at the jointing and grain filling stages and decreased at the heading stage by alkali stress; （iii） alkali stress increased the SOD activity during the heading and grain filling stages, and increased the POD activity at the heading stage. As compared to the control, the increase of MDA contents in alkali-treated oat was observed, during the jointing, heading and grain filling stages; （iv） under alkali stress, the oat genotype Vao-9 showed higher antioxidant enzyme activity and lower soluble sugar contents during the heading stage, and lower MDA contents than those in the oat genotype Baiyan 5 under alkali stress. The result suggested that the high ROS scavenging capacity and soluble sugar levels might play roles in oat response to alkali stress,

关键词： oat alkali stress MDA soluble sugar antioxidant enzyme yield

Collisionless tool orientation smoothing above blade stream surface using NURBS envelope

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第3期14卷 187-197页

作者： Jing-hua XU Shu-you ZHANG Jian-rong TAN Ri-na sa State Key laboratory of Fluid Power Transmission and Control Zhejiang University

In five-axis machining,tool orientation above a blade stream surface may lead to tool collision and a decrease in workpiece ***,collisionless tool orientation smoothing(TOS)becomes an important *** the basis of a constant scallop height tool path,the triangular facets in the faces,vertices format are constructed from cutter contact(CC)using the Voronoi incremental *** cutter location(CL)points candidate set is represented by an oblique elliptic cone whose vertex lies at CC using NURBS *** the CL point is above its CC is judged by the dot product between the normal vector and the point on triangulation nearest to the CL *** curvatures at CC are obtained by fitting a moving least square(MLS) quadratic patch to the local neighborhood of a vertex and calculating eigenvectors and eigenvalues of the Hessian *** surface elastic energy is employed as the weight in selection from the NURBS *** collision is judged by NURBS surface *** can then be expressed by selecting a CL point for each CC point and converted into a numerical control(NC)code automatically according to the postprocessor type of the machine *** proposed method is verified by finishing of a cryogenic turboexpander impeller of air separation equipment.

关键词： Tool orientation smoothing(TOS) Blade stream surface Triangular facet NURBS envelope Surface elastic energy

Effects of human disturbance on nest placement of the woodpigeon (Columba palumbus): a case study from the Middle Atlas, Morocco

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Integrative Zoology 2014年第3期9卷 349-359页

作者： saâd HAnaNE Forest Research Center High Commissariat for WaterForests and Desertification ControlRabat-AgdalMorocco

The woodpigeon(Columba palumbus)is a common and widespread bird in Morocco(North Africa).I examined,over 2 years(2010 and 2011),the breeding density and nest placement of this game species in relation to nest site habitat and degree of human *** study area was in the Middle Atlas Tighboula mountain forest,Morocco,in a disturbed and an undisturbed *** data collected in the 2 study sites,I aimed to identify the factors influencing the placement of nests within holm oak trees(Quercus rotundifolia)and their densities.I found that habitat structures,influenced by grazing disturbance,have affected nesting density and the location of nests of this *** place their nests in a higher position(3.42±0.19 m)when disturbance intensity is high and lower(1.68±0.1 m)when disturbance intensity is low,and show higher nesting density in less disturbed zone(3.1±0.4 nests/ha)than in highly disturbed zones(1.4±0.2 nests/ha).Grazing disturbance could pose a threat to population persistence at a broader scale and could potentially reduce the abundance of this species by altering the composition and the structure of the forest nesting *** multi-scale studies are needed to assess the effects of different levels of grazing disturbance on woodpigeon nest density and placement,and to enhance our knowledge of the breeding behavior of this game species under variable environments.

关键词： breeding density Columba palumbus holm oak Middle Atlas Morocco nest location woodpigeon

Comparative study of three types of controllers for DFIG in wind energy conversion system

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Protection and Control of Modern Power Systems 2018年第1期3卷 223-234页

作者： saïd Boubzizi Hafedh Abid Ahmed el hajjaji Mohamed Chaabane lab-STA laboratory National Engineering School of SfaxRoute de la Soukra3029 SfaxTunisia MIS laboratory University of Picardie Jules Verne33Rue Saint-Leu80039 AmiensFrance

This paper presents an enhanced control strategy for Wind Energy Conversion System(WECS)using Doubly-Fed Induction Generator(DFIG).A robust Super-Twisting(STW)sliding mode control for variable speed wind turbine is developed to produce the optimal aerodynamic torque and improve the dynamic performance of the *** electromagnetic torque of the DFIG is directly tracked using the proposed control to achieve maximum power *** performance and the effectiveness of the STW control strategy are compared to conventional Sliding Mode(SM)and Proportional-Integral(PI)*** proposed STW algorithm shows interesting features in terms of chattering reduction,finite convergence time and robustness against parameters variations and system disturbances.

关键词： Wind turbine(WT) Doubly-fed induction generator(DFIG) Power generation STW(super-twisting) Second order sliding mode control(SOSMC) PI controller

Compensation trends of the angulation of first molars:retrospective study of 1403 malocclusion cases

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International Journal of Oral Science 2014年第3期6卷 175-181页

作者： Hong Su Bing Han sa Li Bin na Wen Ma Tian-Min Xu Department of Orthodontics School and Hospital of Stomatology Peking University Department of Stomatology Shenzhen People’s Hospital Graduate from School and Hospital of Stomatology Peking University Arrail International Dental Clinic

We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1 403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First,angulation of the upper first molar varied significantly with age and tipped most distally in cases aged,12 years and least distally in cases aged.16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensa.ed for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.

关键词： Angle classification angulation compensation first molar growth stages malocclusion sagittal skeletal patterns verticalskeletal patterns

Microbiological assessment of indoor air of a teaching hospital in Nigeria

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Asian Pacific Journal of Tropical Biomedicine 2012年第6期2卷 465-468页

作者： Awosika sa Olajubu FA Amusa na Department of Microbiology Olabisi Onabanjo University Department of Medical Microbiology & Parasitology Olabisi Onabanjo University Teaching Hospital Department of Plant Science & Applied Zoology Olabisi Onabanjo University

Objective:To investigate the quality of indoor air of different wards and units of Olabisi Onabanjo University Teaching Hospital, sagamu, to ascertain their contribution to infection rate in the ***:The microbial quality of indoor air of nine wards/units of Olabisi Onabanjo University Teaching Hospital, sagamu, Nigeria was conducted. Sedimentation technique using open Petri-dishes containing different culture media was employed and samplings were done twice daily, one in the morning shortly after cleaning and before influx of people/patients into the wards/units and the other in the evening when a lot of activities would have taken place in these wards. Isolates were identified according to standard ***:Results showed that there was a statistically significant difference(氈2= 6.0167) in the bacteria population of the different sampling time whereas it was not so for fungi population(氈2= 0.2857). Male medical ward(MMW) and male surgical general(MSG) recorded the highest bacterial and fungal growth while the operating theatre(OT) was almost free of microbial burden. The bacteria isolates were Staphylococcus aureus, Klebsiellasp., Bacillus cereus, Bacillus subtilis, Streptococcus pyogenes andSerratia marscenceswhile the fungi isolates includedAspergillus flavus, Penicilliumsp.,Fusariumsp.,Candida *** aureuswas the predominantly isolated bacterium whilePenicilliumsp. was the most isolated ***:Though most of the microbial isolates were potential and or opportunistic pathogens, there was no correlation between the isolates in this study and the surveillance report of nosocomial infection during the period of study, hence the contribution of the indoor air cannot be established. From the reduction noticed in the morning samples, stringent measures such as proper disinfection and regular cleaning, restriction of patient relatives' movement in and out of the wards/units need to be enforced so as to imp

关键词： Indoor air OOUTH Open-plate technique Nosocomial infections Staphylococcus aureus Microbiological assessment Microbial quality Bacterial isolate Fungal isolate Opportunistic pathogen Nosocomial infection Infection rate Microbial isolate Penicilliumsp Sedimentation technique

Boosting Oxygen Evolution Reaction Performance on NiFe‑Based Catalysts Through d‑Orbital Hybridization

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nano-Micro Letters 2025年第1期17卷 281-292页

作者： Xing Wang Wei Pi Sheng Hu Haifeng Bao na Yao Wei Luo State Key laboratory of New Textile Materials and Advanced Processing Technology Key Laboratory of New Textile Materials and Applications of Hubei ProvinceSchool of Materials Science and EngineeringWuhan Textile UniversityWuhan 430200People’s Republic of China College of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072People’s Republic of China

Anion-exchange membrane water electrolyzers(AemWEs)for green hydrogen production have received intensive attention due to their feasibility of using earth-abundant NiFe-based *** introducing a third metal into NiFe-based catalysts to construct asymmetrical M-NiFe units,the d-orbital and electronic structures can be adjusted,which is an important strategy to achieve sufficient oxygen evolution reaction(OER)performance in ***,the ternary NiFem(M:la,Mo)catalysts featured with distinct M-NiFe units and varying d-orbitals are reported in this *** and theoretical calculation results reveal that the doping of la leads to optimized hybridization between d orbital in NiFem and 2p in oxygen,resulting in enhanced adsorption strength of oxygen intermediates,and reduced rate-determining step energy barrier,which is responsible for the enhanced OER *** critically,the obtained NiFela catalyst only requires 1.58 V to reach 1 A cm^(−2) in an anion exchange membrane electrolyzer and demonstrates excellent long-term stability of up to 600 h.

关键词： NiFe-based catalysts d-orbital coupling Oxygen evolution reaction Anion exchange membrane electrolyzer

Malignancy and mortality in a population-based cohort of patients with coeliac disease or ‘gluten sensitivity’

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World Journal of Gastroenterology 2007年第1期13卷 146-151页

作者： la Anderson sa McMillan RGP Watson P Monaghan AT Gavin C Fox LJ Murray Queen's University Belfast Centre for Clinical and Population Sciences Belfast United Kingdom Royal Group of Hospitals Regional Immunology Service Belfast United Kingdom Royal Group of Hospitals Institute of Clinical Science Belfast United Kingdom. Queen's University Belfast Northern Ireland Cancer Registry Belfast United Kingdom

AIM: To determine the risk of malignancy and mortality in patients with a positive endomysial or anti-gliadin an- tibody test in Northern Ireland. METHODS: A population-based retrospective cohort study design was used. laboratory test results used in the diagnosis of coeliac disease were obtained from the Regional Immunology laboratory, cancer statistics from the Northern Ireland Cancer Registry and mortal- ity statistics from the General Registrar Office, Northern Ireland. Age standardized incidence ratios of malignant neoplasms and standardized mortality ratios of all-cause and cause-specific mortality were calculated. RESULTS: A total of 13 338 people had an endomysial antibody and/or an anti-gliadin antibody test in Northern Ireland between 1993 and 1996. There were 490 pa- tients who tested positive for endomysial antibodies and they were assumed to have coeliac disease. There were 1133 patients who tested positive for anti-gliadin anti- bodies and they were defined as gluten sensitive. Ma- lignant neoplasms were not significantly associated with coeliac disease; however, all-cause mortality was signifi- cantly increased following diagnosis. The standardized incidence and mortality ratios for non-Hodgkin’s lym- phoma were increased in coeliac disease patients but did not reach statistical significance. Lung and breast cancer incidence were significantly lower and all-cause mortal-ity, mortality from malignant neoplasms, non-Hodgkin’s lymphoma and digestive system disorders were signifi- cantly higher in gluten sensitive patients compared to the Northern Ireland population. CONCLUSION: Patients with coeliac disease or gluten sensitivity had higher mortality rates than the Northern Ireland population. This association persists more than one year after diagnosis in patients testing positive for anti-gliadin antibodies. Breast cancer is significantly re- duced in the cohort of patients with gluten sensitivity.

关键词： Coeliac disease Cancer Mortality Gluten sensitivity