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Phase Formation and Magnetic Properties of Nanocomposite Nd-Fe-b Adjusted by Small Amount of Dy and Co

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Journal of Rare Earths 2004年第z2期22卷 89-94页

作者： T S Jang T W Lim H S Aum D H Lee M b Kim Division of Materials and Chemical Engineering Sun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Mechanical EngineeringSun Moon University 100 Kalsan LiTangjung MyonAsan CityChoongnam 336-708Korea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea

In order to improve and stabilize the magnetic properties of nanocomposite Nd2Fe14b/α-Fe magnetic alloys by a compositional adjustment, small amount of Dy and/or Co was added to Nd9Fe84b7 alloys. DTA analysis on the amorphous of the alloys took place as the soft magnetic phases were crystallized, and then the hard magnetic Nd2Fe14b was precipitated from them. While α-Fe and a metastable 1:7 (TbCu7-type) phase were formed simultaneously in Dy and Co-free alloys, they were crystallized separately at different temperatures after Dy or Co was added. This phase separation occurred more clearly in the Dy-treated alloys and the other soft magnetic phase Fe3b was also stabilized by Dy and/or Co. The 1: 7 phase that was stabilized by Dy and/or Co was not eliminated at 700 ℃, decreasing magnetic properties of the alloys. It was eventually disappeared above 725 ℃, but Fe3b was not eliminated even at 750 ℃ when Dy was added more than 0.5 at% or Co was added more than 2.0 at%. Amount of Nd2Fe14b in the alloys tended to increase as Dy addition increased,whereas Co addition did not lead to any appreciable change in the ratio of α-Fe and Nd2Fe14b. Moreover, Dy addition apparently increased coercivity of an alloy while Co addition had a beneficial effect on remanence. The grains in the Dytreated alloys were usually finer than those in the Co-treated alloys. The grain size of both α-Fe and Nd2Fe14b in the alloys exhibiting mr ≥ 0.72 was in the range of 20 ～ 40 nm or even larger 50 nm, which is larger than the theoretical optimum size ( ～ 10 nm). Typical magnetic properties obtained from a Nd7.5Dy1.5Fe82.5Co1.5b7 alloy annealed for 12 min at 725 ℃were iHc=4.85 kOe, br= 11.32 kG, (bH)max = 15.73 MGOe, and mr=0.73.

关键词： nanocomposite Nd-Fe-b magnetic properties remanence coercivity

Compocasting of A356-CNT composite

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1561-1566页

作者： b.AbbASIPOUR b.NIROUM AND S.M.MONIR VAGHEFI Department of Materials Engineering Isfahan University of Technology

A356 aluminum alloys reinforced with carbon nano-tubes (CNTs) were produced by stir casting and compocasting routes and their microstructural characteristics and hardness were *** order to alleviate the problems associated with poor wettability, agglomeration and gravity segregation of CNTs in the melt, CNTs were introduced into the melts by injection of CNT deposited aluminum particles instead of raw *** particles with mean diameters of less than 100 μm were first deposited by CNTs using Ni-P electroless plating technique and then injected into the melt agitated by a mechanical *** slurry was subsequently cast at temperatures corresponding to full liquid as well as 0.15 and 0.30 solid *** results show that addition of CNTs to A356 matrix can significantly refine both full liquid and semi-solid cast *** of the samples is also significantly increased by addition of CNTs and A356-CNT composite cast at 0.3 solid fraction produces the highest hardness.

关键词： A356-CNT composite carbon nano-tube (CNT) compocasting electroless plating microstructure hardness

Influence of TiO_2 on the electrochemical performance of pasted typeβ-nickel hydroxide electrode in alkaline electrolyte

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Journal of Energy Chemistry 2016年第1期25卷 41-48页

作者： b.Shruthi b.J.Madhu V.bheema Raju Department of Chemistry Dr. Ambedkar Institute of Technology Post Graduate Department of Physics Government Science College Department of Chemistry Dayananda Sagar College of Engineering

Nickel hydroxide was used as the positive electrode material in rechargeable alkaline batteries, which plays a significant role in the field of electric energy storage devices. β-nickel hydroxide（β-Ni（OH）2 ） was prepared from nickel sulphate solution using potassium hydroxide as a precipitating agent. Pure β-phase of nickel hydroxide was confirmed from XRD and FT-IR studies. The effects of TiO2 additive on the β-Ni（OH）2 electrode performance are examined. The structure and property of the TiO2 added β-Ni（OH）2 were characterized by XRD, TG-DTA and SEM analysis. A pasted–type electrode is prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry and electrochemical impedance spectroscopy studies were performed to evaluate the electrochemical performance of the β-Ni（OH）2 and TiO2 added β-Ni（OH）2 electrodes in 6 M KOH electrolyte. Anodic（Epa） and cathodic（Epc）peak potentials are found to decrease after the addition of TiO 2 into β-Ni（OH）2 electrode material. Further,addition of TiO2 is found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. Compared with pure β-Ni（OH）2 lectrode,TiO2 added β-Ni（OH）2 electrode is found to exhibit higher proton diffusion coefficient（D） and lower charge transfer resistance. These findings suggest that the TiO2 added β-Ni（OH）2 electrode possess improved electrochemical properties and thus can be recognized as a promising candidate for the battery electrode applications.

关键词： Nickel hydroxide Electrode material Thermogravimetric analysis Electrochemical properties Impedance spectroscopy

PROXIMAL POINT ALGORITHM FOR MINIMIZATION OF DC FUNCTION

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Journal of Computational Mathematics 2003年第4期21卷 451-462页

作者： Wen-yuSun Raimundo.J.b.Sampaio M.A.b.Candido SchoolofMathematicsandComputerScience NanjingNormalUniversityNanjing2100g7China ProgramadePos-GraduacaoemInformaticaAplicada PontificiaUniversidadeCatolicadoParana(PUCPR)CEP:80215-g01CuritibaPRBrazil ProgramadePos-GraduacaoemInformaticaAplicada PontificiaUniversidadeCatolicadoParana(PUCPR)CEP:80215-g01CuritibaPRBrazil

In this paper we present some algorithms for minimization of DC function (difference of two convex functions). They are descent methods of the proximal-type which use the convex properties of the two convex functions separately. We also consider an approximate proximal point algorithm. Some properties of the ε-subdifferential and the ε-directional derivative are discussed. The convergence properties of the algorithms are established in both exact and approximate forms. Finally, we give some applications to the concave programming and maximum eigenvalue problems.

关键词： Nonconvex optimization Nonsmooth optimization DC function Proximal point algorithm ε-subgradient.

Assessment of deterioration in RHA-concrete due to magnesium sulphate attack

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 691-696页

作者： G.A. Habeeb H.b. Mahmud N.b.A.A. Hamid Department of Civil Engineering Faculty of Engineering University of Malaya

The assessment of magnesium sulphate attack on concretes containing rice husk ash （RHA, 20wt% of the cementitious materials） with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio （W/b） was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immersed in the 3wt% magnesium sulphate solution for up to 111 d of exposure. The specimens were subjected to drying-wetting cycles to accelerate sulphate attack. In addition to the visual monitoring of the specimens, the concrete specimens were subsequently tested for compressive strength, dynamic modulus of elasticity, and length and mass changes. The results show that the specimens exposed to sulphate attack exhibit higher strength and dynamic modulus than those kept in water. The length change is negligible and can be attributed to the normal swelling of concrete. On the other hand, concretes suffers mass loss and surface spalling and softening; the fine RHA-concrete results in a better resistance. For the accelerated sulphate attack method used in this study, mass change and visual monitoring are recommended for assessing the deterioration degree and the effectiveness of supplementary cementitious materials to resist sulphate attack.

关键词： concretes pozzolan ettringite rice husk ash (RHA) magnesium sulphate

Implications of oxidative damage to proteins and DNA in aging and its intervention by caloric restriction and exercise

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Journal of Sport and Health Science 2013年第2期2卷 75-80页

作者： Sataro Goto Zsolt radak Institute of Health and Sports Science & Medicine Juntendo University Graduate School Research Institute of Sport Science Semmelweis University

In this short review we describe implications of age-related changes of protein and DNA oxidation as a public mechanism of biological aging. Oxidatively modified protein and DNA have been demonstrated to increase with advancing age in rodents. Half-life of proteins is extended and DNA repair activity declines in old animals. Dietary restriction initiated late in life can shorten the half-life of proteins to levels of young animals, thus contributing to reduce level of altered proteins in old animals by the regimen. Regular exercise reduced oxidatively modified proteins in the brain with improved cognitive functions. It attenuated oxidative stress in the liver, i.e., ameliorating activation of nuclear factor κb, increasing reduced glutathione, and decreasing oxidized guanine base in nuclear and mitochondrial DNA. These findings suggest that regular exercise has systemic effects in reducing oxidative stress. Thus, life-styles such as diet and exercise may extend health span, by up-regulating overall anti-oxidant capacities that include proteins involved in protein turnover and DNA repair, resulting in reduction of damaged proteins and DNA that potentially promote physiological and pathological aging.

关键词： Aging Dietary restriction DNA Exercise Oxidative stress Protein

Artificial neural network approach for rheological characteristics of coal-water slurry using microwave pre-treatment

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International Journal of Mining Science and Technology 2017年第2期27卷 379-386页

作者： b.K.Sahoo S.De b.C.Meikap Department of Chemical Engineering Indian Institute of Technology Research and Development Centre for Iron and Steel Steel Authority of India Limited Chemical Engineering School of Engineering Howard College University of Kwazulu-Natal

Detailed experimental investigations were carried out for microwave pre-treatment of high ash Indian coal at high power level(900 W) in microwave oven. The microwave exposure times were fixed at60 s and 120 s. A rheology characteristic for microwave pre-treatment of coal-water slurry(CWS) was performed in an online bohlin viscometer. The non-Newtonian character of the slurry follows the rheological model of Ostwald de Waele. The values of n and k vary from 0.31 to 0.64 and 0.19 to 0.81 Pa·sn,respectively. This paper presents an artificial neural network(ANN) model to predict the effects of operational parameters on apparent viscosity of CWS. A 4-2-1 topology with Levenberg-Marquardt training algorithm(trainlm) was selected as the controlled ANN. Mean squared error(MSE) of 0.002 and coefficient of multiple determinations(R^2) of 0.99 were obtained for the outperforming model. The promising values of correlation coefficient further confirm the robustness and satisfactory performance of the proposed ANN model.

关键词： Microwave pre-treatment Coal-water slurry Apparent viscosity Artificial neural network back propagation algorithm

Orbits of Ten Visual binary Stars

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Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 415-420页

作者： b. Novakovi Astronomical Observatory Volgina 7 11160 Belgrade 74 Serbia

We present the orbits of ten visual binary stars： WDS 01015＋6922, WDS 01424- 0645, WDS 01461 ＋6349, WDS 04374-0951, WDS 04478＋5318, WDS 05255-0033, WDS 05491＋6248, WDS 06404＋4058, WDS 07479-1212, and WDS 18384＋... 详细信息

关键词： binaries visual

Additive Mappings Preserving Rank-one Idempotents

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Acta Mathematica Sinica,English Series 2005年第6期21卷 1399-1406页

作者： b. KUZMA Institute of Mathematics Physics and Mechanics Department of Mathematics Jadranska 19 1000 Ljubljana Slovcnia

A complete characterization of additive mappings φ ： b（X）→b（Y）, which map rank-one idempotents to themselves or to zero, is given.

关键词： Additive preservers Idempotents Rank