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Electrochemical studies on cerium(Ⅲ) in molten fluoride mixtures

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Journal of Rare Earths 2010年第3期28卷 428-434页

作者： VIRGIL CONSTANTIN ANA-MARIA POPESCU MIRCEA OLTEANU romanian academy Institute of Physical Chemistry "Ilie Murgulescu"Department of Molten Salts Splaiul Independentei 202Bucharest-Romania

This study aims to determine the principal electrochemical characteristics of the electrodeposition of cerium metal from molten fluoride systems.The cathodic process of Ce3+ ions in LiF-NaF and LiF-NaF-CaF2 molten salts was studied using electrochemical techniques as steady state and cyclic voltammetry methods.The decomposition potential(Ed) and the overvoltage(η) were determined for NaCeF4 using current-potential curves under galvanostatic conditions.The Ed was found to be 2.025 V in LiF-NaF and 2.045 V in...

关键词： cerium molten salts lanthanides NaCeF4 electrolysis cyclic voltammetry

A Comparative Analysis of Binary Logistic Regression and Analytical Hierarchy Process for Landslide Susceptibility Assessment in the Dobrovǎt River Basin,Romania

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Pedosphere 2016年第3期26卷 335-350页

作者： Cristian V.PATRICHE Radu PIRNAU Adrian GROZAVU Bogdan ROSCA romanian academy Department of IasiGeography Group "Alexandru Ioan Cuza" University of Iasi Faculty of Geography

A correct assessment of the landslide susceptibility component is extremely useful for the diminution of associated potential risks to local economic development, particularly in regard to land use planning and soil conservation. The purpose of the present study was to compare the usefulness of two methods, i.e., binary logistic regression(BLR) and analytical hierarchy process(AHP), for the assessment of landslide susceptibility over a 130-km^2 area in the Moldavian Plateau(eastern Romania) region, where landslides affect large areas and render them unsuitable for agriculture. A large scale inventory mapping of all types of landslides(covering 13.7% of the total area) was performed using orthophoto images, topographical maps, and field surveys. A geographic information system database was created, comprising the nine potential factors considered as most relevant for the landsliding process. Five factors(altitude, slope angle, slope aspect, surface lithology, and land use) were further selected for analysis through the application of a tolerance test and the stepwise filtering procedure of BLR. For each predictor, a corresponding raster layer was built and a dense grid of equally spaced points was generated, with an approximately equal number of points inside and outside the landslide area, in order to extract the values of the predictors from raster layers. Approximately half of the total number of points was used for model computation, while the other half was used for validation. Analytical hierarchy process was employed to derive factor weights, with several pair-wise comparison matrices being tested for this purpose. The class weights, on a scale of 0 to 1, were taken as normalized landslide densities. A comparison of results achieved through these two approaches showed that BLR was better suited for mapping landslide susceptibility, with 82.8% of the landslide area falling into the high and very high susceptibility classes. The susceptibility class separation using standard deviation was superior to either t

关键词： Logistic回归分析敏感性评价山体滑坡层次分析法罗马尼亚河流域土地利用规划地方经济发展

Construction of a magnesium hydroxide/graphene oxide/hydroxyapatite composite coating on Mg-Ca-Zn-Ag alloy to inhibit bacterial infection and promote bone regeneration

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Bioactive Materials 2022年第12期7卷 354-367页

作者： Bo Yuan Hewei Chen Rui Zhao Xuangeng Deng Guo Chen Xiao Yang Zhanwen Xiao Antoniac Aurora Bita Ana Iulia Kai Zhang Xiangdong Zhu Antoniac Vasile Iulian Shen Hai Xingdong Zhang National Engineering Research Center for Biomaterials Sichuan UniversityChengdu610064China College of Biomedical Engineering Sichuan UniversityChengdu610064China Sichuan Provincial Orthopedic Hospital Chengdu610041China Faculty of Materials Science and Engineering University Politehnica of Bucharest060042BucharestRomania academy of romanian Scientists 050094BucharestRomania

The improved corrosion resistance, osteogenic activity, and antibacterial ability are the key factors for promoting the large-scale clinical application of magnesium (Mg)-based implants. In the present study, a novel nanocomposite coating composed of inner magnesium hydroxide, middle graphene oxide, and outer hydroxyapatite (Mg(OH)_(2)/GO/HA) is constructed on the surface of Mg-0.8Ca-5Zn-1.5Ag by a combined strategy of hydrothermal treatment, electrophoretic deposition, and electrochemical deposition. The results of material characterization and electrochemical corrosion test showed that all the three coatings have high bonding strength, hydrophilicity and corrosion resistance. In vitro studies show that Mg(OH)2 indeed improves the antibacterial activity of the substrate. The next GO and GO/HA coating procedures both promote the osteogenic differentiation of MC3T3-E1 cells and show no harm to the antibacterial activity of Mg(OH)2 coating, but the latter exhibits the best promoting effect. In vivo studies demonstrate that the Mg alloy with the composite coating not only ameliorates osteolysis induced by bacterial invasion but also promotes bone regeneration under both normal and infected conditions. The current study provides a promising surface modification strategy for developing multifunctional Mg-based implants with good corrosion resistance, antibacterial ability and osteogenic activity to enlarge their biomedical applications.

关键词： Mg alloy Composite coating Corrosion resistance Antibacterial ability Osteogenic activity

Synthesis, Characterization and Thermophysical Properties of Three Neoteric Solvents-Ionic Liquids Based on Choline Chloride

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Chemical Research in Chinese Universities 2014年第1期30卷 119-124页

作者： POPESCU Ana-Maria CONSTANTIN Virgil Laboratory of Molten Salts llie Murgulescu Institute of Physical Chemistry of the Romanian Academy Bucharest 006021 Romania

The authors prepared,characterized and preliminary studied the properties of some neoteric solvents-ionic liquids based on choline chloride,i.e.,three ionic liquids based on the eutectics of choline chloride（2-hydroxyN,N,N-trimethylethanaminium chloride） with,respectively,urea,malonic acid and citric acid.The obtained mixtures were clear and colorless ionic liquids at room temperature.The thermophysical properties,namely,density,viscosity,and electrical conductivity of these mixtures were investigated as a function of temperature within a range of 298-353 K.Correlations for the temperature dependence of the measured properties were generated and discussed in terms of Arrhenius theory.Finally the electrochemical windows of the eutectic liquids were determined.

关键词： Neoteric solvent Ionic liquid Choline chloride Malonic acid Citric acid Density Viscosity Conductivity

New statistical results on the optical IDV data of BL Lac S5 0716+714

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Research in Astronomy and Astrophysics 2015年第3期15卷 327-332页

作者： Bogdan Dǎnilǎ Alexandru Marcu Gabriela Raluca Mocanu Faculty of Physics Babes-Bolyai University romanian academy Astronomical Institute Astronomical Observatory Cluj-Napoca

This paper reports on the statistical behavior of the optical Intraday Variability of BL Lac S5 0716＋714. Available Intraday Variability data in the opti- cal are tested to see whether or not the magnitude is lognormally distributed. Our results consistently indicate that this is not the case. This is in agreement with a previ- ous discussion about data for the same object but in a different observational period. Simultaneously, the spectral slope of the light curves is calculated. The implications of these findings on models that describe both the location and source of Intraday Variability are presented.

关键词： radiation mechanisms non-thermal -- BL Lacertae objects individual：S5 0716＋714

Structure and heat capacity of the NaCeF_4 compound

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Journal of Rare Earths 2013年第9期31卷 911-915页

作者： Virgil Constantin Ana-Maria Popescu "Ilie Murgulescu" Institute of Physical Chemistry of the romanian academy Splaiul Independentei 202 st.060021BucharestRomania

This work continued our general research program on obtaining metallic cerium by electrodeposition from NaCeF4 dis-solved in different molten fluorides. The structure of NaCeF4 （cubic or hexagonal depending on the way of preparation） was estab-lished by DTA analysis, IR spectra and X-ray diffraction. The heat capacity （Cp） of NaCeF4 was measured by differential scanning calorimetry in the temperature range of 300-1093 K using the“step-method”. The Cp was fitted by an equation with a satisfactory re-sult. Heat capacity was compared with that calculated from the Neumann-Kopp rule （NKR） and the deviations observed were consis-tent with the stability of the NaCeF4 compound.

关键词： cerium compounds structure heat capacity NaCeF4 rare earths

Measures Not Charging Polar Sets and Schrodinger Equations in L^p

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Acta Mathematica Sinica,English Series 2010年第2期26卷 249-264页

作者： Lucian BEZNEA Nicu BOBOC Institute of Mathematics "Simion Stoilow" of the romanian academy University of Pitesti Faculty of Mathematics and Computer Science University of Bucharest

We study the SchrSdinger equation （q -￡）u ＋μu = f, where ￡ is the generator of a Borel right process and μ is a signed measure on the state space. We prove the existence and uniqueness results in Lp, 1 ≤p 〈∞ . Since we consider measures μcharging no polar set, we have to use new tools： the Revuz formula with fine versions and the appropriate Revuz correspondence, the perturbation （subordination） operators （in the sense of G Mokobodzki） induced by the regular strongly supermedian kernels. We extend the results on the SchrSdinger equation to the case of a strongly continuous sub-Markovian resolvent of contractions on Lp. If the measure μ is positive then the perturbed process solves the martingale problem for ￡- μ and its transition semigroup is given by the Feynman-Kac formula associated with the left continuous additive functional having μ as Revuz measure.

关键词： SchrSdinger equation LP-resolvent measure perturbation Revuz correspondence right

General Solutions for Hydromagnetic Free Convection Flow over an Infinite Plate with Newtonian Heating, Mass Diffusion and Chemical Reaction

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Communications in Theoretical Physics 2017年第12期67卷 768-782页

作者： Constatin Fetecau Nehad Ali Shah Dumitru Vieru academy of romanian Scientists Abdus Salam School of Mathematical Sciences GC University Lahore Technical University of Iasi

The problem of hydromagnetic free convection flow over a moving infinite vertical plate with Newtonian heating, mass diffusion and chemical reaction in the presence of a heat source is completely solved. Radiative and porous effects are not taken into consideration but they can be immediately included by a simple rescaling of Prandtl number and magnetic parameter. Exact general solutions for the dimensionless velocity and concentration fields and the corresponding Sherwood number and skin friction coefficient are determined under integral form in terms of error function or complementary error function of Gauss. They satisfy all imposed initial and boundary conditions and can generate exact solutions for any problem with technical relevance of this type. As an interesting completion, uncommon in the literature, the differential equations which describe the thermal, concentration and momentum boundary layer, as well as the exact expressions for the thicknesses of thermal, concentration or velocity boundary layers were determined.Numerical results have shown that the thermal boundary layer thickness decreases for increasing values of Prandtl number and the concentration boundary layer thickness is decreasing with Schmidt number. Finally, for illustration,three special cases are considered and the influence of physical parameters on some fundamental motions is graphically underlined and discussed. The required time to reach the flow according with post-transient solution(the steady-state),for cosine/sine oscillating concentrations on the boundary is graphically determined. It is found that, the presence of destructive chemical reaction improves this time for increasing values of chemical reaction parameter.

关键词： hydromagnetic free convection Newtonian heating heat source mass diffusion chemical reaction general solutions

Current Efficiency, Corrosion and Structural Changes in SnO2-Sb2O3-CuO Inert Anodes for Aluminium Electrolysis

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Chinese Journal of Chemical Physics 2014年第3期27卷 368-372页

作者： Ana-Maria Popescu Virgil Constantin Ilie Mur&ulescu Institute of Physical Chemistry of the romanian academy Splaiul Independentei 202060021 Bucharest Romania

系统的研究在电流上被进行在基于 SnO2 的惰性的阳极的效率(CE ) ，腐蚀和结构的变化(用 96wt%SnO2+2wt%Sb2O3+2wt%CuO 做的) 在一个实验室 Hall-Heroult 铝房间上。在 CE 和腐蚀过程上操作参数和电解质作文的影响被评估。CE 被发现是超... 详细信息

系统的研究在电流上被进行在基于 SnO2 的惰性的阳极的效率(CE ) ，腐蚀和结构的变化(用 96wt%SnO2+2wt%Sb2O3+2wt%CuO 做的) 在一个实验室 Hall-Heroult 铝房间上。在 CE 和腐蚀过程上操作参数和电解质作文的影响被评估。CE 被发现是超过 90% ，灾难的腐蚀发生在 Al2O3， LiF 的高百分比，低冰晶石比率和高当前的密度的低百分比点。从发生在基于 SnO2 的惰性的阳极的所有结构的变化，我们假设最重要的贡献由于向基于的 SnO2 的成分谷物的外部限制的 CuO 的迁居陶器。复杂过程在各种各样的阶段的形成期间发生了，他们的 sintering 能力直接两个都取决于 Cu/Sb 臼齿的比率。

关键词：三氧化二锑二氧化锡惰性阳极电流效率氧化铜耐腐蚀铝电解槽结构