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Allelopathic effect of Acorus tatarinowii upon algae

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Journal of Environmental Sciences 2001年第4期13卷 481-484页

作者： He, c.-q. Wang, c.-k. Dept. of Environmental Science/Eng. Shanghai University Shanghai 200072 China

Besides competing with algae for light and mineral nutrients (i. e. N, P, etc.), the root system of Acorus tatarinowii excretes some chemical substances, which injure and eliminate alga cells, to inhibit the growth of the algae. When the algae cells were treated in 'A. tatarinowii water', some of the chlorophyll a were destroyed and the photosynthetic rate of algae decreased markedly and the ability of alga cells to deoxidize triphenyltetrazolium chloride (TTc) reduced greatly. Then alga cells turned from bright red to bluish green under fluorescence microscope. These showed that the allelopathic effects of A. tatarinowii on algae were obvious and planting A. tatarinowii can control some green algae. The experiment on the extractions of the secretions of the root system showed that the inhibitory effect had a concentration effect. If the concentration of the root secretion was below 30 μl/disc, the inhibitory rate was negative; if it was over 45 μl/disc, the inhibitory rate was positive. This proved that the influence of the root secretion on the same acceptor was a kind of concentration effect. When the concentration of the root secretion was low, it promoted the growth of algae; when the concentration reached a definite threshold value, it restrained the growth of algae. In present case, the threshold value was between 30 μl/disc and 45 μl/disc.

关键词： Algae cells chlorophyll concentration (process) Deoxidants Photosynthesis

Reduction effect of final-pass heavy reduction rolling on the texture development,tensile property and stretch formability of ZWK100 alloy plates

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Journal of Materials Science & Technology 2022年第16期111卷 211-223页

作者： B.q.Shi L.Y.Zhao X.L.Shang B.H.Nie D.c.chen c.q.Li Y.q.cheng School of Materials Science and Hydrogen Energy Foshan UniversityFoshan 528000China School of Materials and Energy Guangdong University of TechnologyGuangzhouGuangdong 510006China GD Midea Air-conditioning Equipment co. Ltd.Foshan 528311China Guangdong Key Laboratory of Hydrogen Energy Technology Foshan 528000China YunFu(Foshan)R&D center of Hydrogen Energy Standardization Yunfu 527326China

Obviously planar anisotropy due to‘TD split’orthotropic texture(TD indicates Transverse direction)always exist in the Rare-earth(RE)or ca containing Mg alloy sheets,which is likely caused by the lowreduction rolling(and annealing)as revealed in our previous *** this work,the as-cast billets of a ZWK100 alloy were subjected to final-pass heavy reduction rolling(FHRR)at 500°c with different reductions(30%-70%)after rough rolling,aiming to investigate the reduction effect on the microstructure and texture *** results show that FHRR with higher reductions above 50%is in favor of shear banding formation but has little effect on the as-deformed texture components,and the excellent formability with single-pass reduction up to 70%is mainly ascribed to the activation of prismatic *** with reduction above 50%and annealing can generate uniform grain structures of~10μm and symmetrical‘oblique-line split’texture in(0001)pole figures,with basal poles tilting by about 50°from ND(Normal direction)towards some oblique-line of TD and RD(Rolling direction)as well as uniform distribution of counter lines as an annular shape,resulting in excellent elongation to failure of~50%and ultra-low planar anisotropyΔr_of~0.1 and high stretch formability(Erichsen value:8.1).The formation‘oblique-line split’texture in(0001)pole figures is mainly correlated with the preferred growth tendency of grains with■//RD,which was suggested to relate to the high mobility of some special boundaries such as 40°-45°■.The influences of starting textures on the mechanical properties,planar anisotropy and related deformation modes,as well as their correlations with the stretch formability were comparatively investigated with the‘TD split’orthotropic texture as a counterpoint.

关键词： Magnesium alloys Texture Plane anisotropy Stretch formability Rolled sheets

Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies

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Research in Astronomy and Astrophysics 2011年第12期11卷 1429-1448页

作者： James q.Feng c.F.Gallo Superconix Inc 2440 Lisbon AvenueLake ElmoMN 55042USA

We present an efficient, robust computational method for modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies. With appropriate mathematical treatments, the apparent numerical difficulties associated with singularities in computing elliptic integrals are completely removed. Using a boundary element discretization procedure, the governing equations are transformed into a linear algebra matrix equation that can be solved by straightforward Gauss elimination in one step without further iterations. The numerical code implemented according to our algorithm can accurately determine the surface mass density distribution in a disk galaxy from a measured rotation curve （or vice versa）. For a disk galaxy with a typical flat rotation curve, our modeling results show that the surface mass density monotonically decreases from the galactic center toward the periphery, according to Newtonian dynamics. In a large portion of the galaxy, the surface mass density follows an approximately exponential law of decay with respect to the galactic radial coordinate. Yet the radial scale length for the surface mass density seems to be generally larger than that of the measured brightness distribution, suggesting an increasing mass-tolight ratio with the radial distance in a disk galaxy. In a nondimensionalized form, our mathematical system contains a dimensionless parameter which we call the ＂galactic rotation number＂ that represents the gross ratio of centrifugal force and gravitational force. The value of this galactic rotation number is determined as part of the numerial solution. Through a systematic computational analysis, we have illustrated that the galactic rotation number remains within 4-10% of 1.70 for a wide variety of rotation curves. This implies that the total mass in a disk galaxy is proportional to V02 Rg, with V0 denoting the characteristic rotation velocity （such as the ＂flat＂ value in a typical ro- tation curve） and Rg the radius of the galacti

关键词： galaxy: disk -- galaxies: general -- galaxies: kinematics and dynamics -- galaxies: structure -- methods: numerical and analytical

Formation of β' phase in LPSO structures in an Mg88co5Y7 alloy

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Journal of Magnesium and Alloys 2022年第1期10卷 175-182页

作者： q.q.jin X.H.Shao Y.T.Zhou B.Zhang S.J.Zheng X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua Road110016 ShenyangChina Materials Science and Engineering Research center Guangxi University of Science and TechnologyLiuzhou 545006China School of Materials Science and Engineering Research Institute for Energy Equipment MaterialsHebei University of TechnologyTianjin 300130China

Formation of β’ phase in long-period stacking ordered(LPSO) structures in an Mg;co;Y;(at.%) alloy after aging at 200 °c for 24 h or electron beam(EB) irradiation has been studied by high-angle annular dark-field scanning transmission electron microscopy(HAADFSTEM). β’ phase was precipitated only in the Mg matrix but not in LPSO structures after aging at 200 °c for 24 h. LPSO structure containing stacking defects transforms into the β’-long phase during EB irradiation, which plays a key role in accelerating solute atoms’ diffusion. New complex β’(LPSO) structures formed in the alloy after EB irradiation, such as β’(12 H) structure with an orthorhombic lattice(Mg;Y, cmcm,a = 2 _(a0)= 0.642 nm, b=4√3_(a0), c = 6 _(c0)= 3.12 nm).

关键词： Magnesium alloys Long-period stacking ordered(LPSO)structure HAADF-STEM β’phase

Experimental study of the effect of wear parameters on the wear behavior of A356 alloy/cow horn particulate composites

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Defence Technology（防务技术） 2018年第1期14卷 77-82页

作者： B.q.Ochieze c.c.Nwobi-Okoye P.N.Atamuo Lafarge Africa Plc Mfamosing Plant Department of Mechanical Engineering Chukwuemeka Odumegwu Ojukwu University

Experimental study of the effect of wear parameters on the wear behaviour of A356 alloy reinforced with cow horn particles(cHp) produced by spark plasma sintering was investigated. Experiments were conducted based on the plan of experiments generated through Taguchi's(L9) technique. Tribometer was used for the wear test and Scanning electron microscope was used to analyse the worn scar of the samples. The results shows that, A356 alloy reinforced with cHp exhibited better dry sliding wear resistance than the unreinforced alloy. Wear rate decreased as the amount of cHp reinforcement increased in the matrix. It was found that, the optimum level of the factors with minimized the wear loss were obtained at: wt%cHp(20%), applied load(10 N), sliding velocity(3 m/s) and sliding distance(2000 m). It can be seen that the wear track of the sample are(D ? 0.81 and L = 42.85 mm) and(D ? 0.54 and L= 27.03 mm) for A356 alloy and composites at optimum condition respectively. The results showed that the addition of cow horn particles as reinforcing materials in A356 alloy composites increased the wear resistance of the composites greatly.

关键词： A356alloy cow horn particles Microstructure Analysis of variance and wear behaviour

correlation between test temperature, applied load and wear transition of Mg97Zn1Y2 alloy

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Journal of Magnesium and Alloys 2021年第2期9卷 592-603页

作者： J.An Y.X.Tian c.q.Feng Key Laboratory of Automobile Materials Ministry of EducationDepartment of Materials Science and EngineeringJilin UniversityChangchun 130025PR China

Dry sliding wear tests were performed on Mg97 Zn1 Y2 alloy at various temperatures of 20,50,100,150 and 200°c using a pin-on-disc wear testing machine in order to reveal mild-severe(M-S)wear transition mechanism during elevated-temperature wear *** was shown that at each test temperature,the wear rate increased with increasing load,and all wear rate-load curves demonstrated two distinct stages *** and severe wear *** predominant wear mechanisms operating in mild and severe wear stages were analyzed,and they were indicated in the mild and severe wear regimes of a wear mechanism transition map,respectively.M-S wear transition mechanism was analyzed by comparison of microstructure transformation and hardness change in subsurfaces of samples tested in mild and severe wear stages,from which M-S wear transition mechanism was confirmed as softening of surface material arising from dynamic recrystallization(DRX)microstructure *** M-S wear transition load was found to have a linear relationship with test temperature,and decreased with rising test temperature.M-S wear transition obeyed a critical surface DRX temperature(SDT)criterion under given conditions,and the transition loads were estimated at various test temperatures by using the criterion.

关键词： Mg-alloys Elevated temperatures Wear rate Wear mechanism Wear transition

Diffusion behavior at void tip and its contributions to void shrinkage during solid-state bonding

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Journal of Materials Science & Technology 2018年第8期34卷 1449-1454页

作者： c.Zhang M.q.Li H.Li School of Materials Science and Engineering Northwestern Polytechnical University State Key Laboratory of Solidification Processing Northwestern Polytechnical University Department of Mechanical Engineering University de Lyon

Solid-state diffusion bonding is an advanced joining technique, which has been widely used to join similar or dissimilar materials. Generally, it is easy to observe the diffusion behavior during dissimilar bonding, but for similar bonding the diffusion behavior has yet been observed via experiments. In this study, the diffusion behavior at void tip was firstly observed during similar bonding of stainless steel. Scanning electron microscopy with energy dispersive spectroscopy was used to examine the interface charac- teristic and diffusion behavior. The results showed that a diffusion region was discovered at void tip. Element concentrations of diffusion region were more than those of void region, but less than those of bonded region. This behavior indicated that the diffusion was ongoing at void tip, but the perfect bond has yet formed. The diffusion region was attributed to the interface diffusion from adjacent region to void tip due to the stress gradient along bonding interface. The mass accumulation at void tip transformed the sharp void tip into smooth one at the beginning of void shrinkage, and then resulted in shorter voids.

关键词： Stainless steel Micro-void morphology Solid-state bonding Void tip Element diffusion

Automotive revolution and carbon neutrality

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Frontiers in Energy 2023年第6期17卷 693-703页

作者： c.c.cHAN Wei HAN Hanlei TIAN Yanbing LIU Tianlu MA c.q.JIANG Department of Electrical and Electronic Engineering The University of Hong KongHong KongChina Sustainable Energy and Environment Thrust Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511453China Department of Electronic and computer Engineering Hong Kong University of Science and TechnologyHong KongChina Department of Electrical Engineering City University of Hong KongHong KongChina HKUST Shenzhen-Hong Kong collaborative Innovation Research Institute Shenzhen 518048China

The automotive industry is in the midst of a groundbreaking revolution,driven by the imperative to achieve intelligent driving and carbon neutrality.A crucial aspect of this transformation is the transition to electric vehicles(EVs),which necessitates widespread changes throughout the entire automotive *** paper examines the challenges and opportunities of this transition,including automotive electrification,intelligence-connected transportation system,and the potential for new technologies such as hydrogen fuel ***,it discusses the key technologies and progress of the hydrogen energy industry chain in the upstream hydrogen production,midstream hydrogen storage and transportation,downstream hydrogen station construction and hydrogen fuel cells in ***,it proposes the directions for future layout,providing guidance for future development.

关键词： automotive revolution electric vehicles(EVs) hydrogen energy fuel cell

Microstructural Stability of a Single crystal Superalloy DD8 during Thermal Exposure

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Journal of Materials Science & Technology 2008年第1期24卷 127-130页

作者： K.Y.cheng D.H.Kim Y.S.Yoo c.Y.Jo T.jin Z.q.Hu SuperalloyDivision Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China High Temperature Materials Group KIMS Changwon Korea Materials Test and characterization Group KIMS Changwon Korea

Microstructural stability of a nickel base single crystal alloy DD8 has been *** heat treated specimen showed good microstructural stability at 950℃.While under the as-cast condition,a kind of rod-like phase precipitated in the interdendritic region of as-cast specimen during thermal *** phase,which has bcc structure,was enriched with ***-calc also predicted precipitation of a bcc phase at around 950℃.The cr-rich bcc phase was considered asα-cr and formed due to the segregation of cr under the as-cast condition.

关键词： DD-8 Single crystal alloy Microstructural stability Alpha chromium