985 resultados para ~(46)Sc


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Using first-principles methods we have calculated electronic structures, optical properties, and hole conductivities of CuXO2 (X=Y, Sc, and Al). We show that the direct optical band gaps of CuYO2 and CuScO2 are approximately equal to their fundamental band gaps and the conduction bands of them are localized. The direct optical band gaps of CuXO2 (X=Y, Sc, and Al) are 3.3, 3.6, and 3.2 eV, respectively, which are consistent with experimental values of 3.5, 3.7, and 3.5 eV. We find that the hole mobility along long lattice c is higher than that along other directions through calculating effective masses of the three oxides. By analyzing band offset we find that CuScO2 has the highest valence band maximum (VBM) among CuXO2 (X=Y, Sc, and Al). In addition, the approximate transitivity of band offset suggests that CuScO2 has a higher VBM than CuGaO2 and CuInO2 [Phys. Rev. Lett. 88, 066405 (2002)]. We conclude that CuScO2 has a higher p-type doping ability in terms of the doping limit rule. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2991157]

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SnS/SnO heterojunction structured nanocrystals with zigzag rod-like connected morphology were prepared by using a simple two-step method. Bulk heterojunction solar cells were fabricated using the SnS/SnO nanocrystals blended with poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) (MDMO-PPV) as the active layer. Compared with solar cells using SnS nanoparticles hybridized with MDMO-PPV as the active layer, the SnS/SnO devices showed better performance, with a power conversion efficiency higher by about one order in magnitude.

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本课题是荷兰DSM公司委托研究课题,目的是在保留或基本保留怪尼龙46(PA46)的基本力学性能的情况下,降低PA46的成本,改善其吸水率高、尺寸稳定性差、电性能不好等缺点。有反应挤出法制备了甲基丙烯酸环氧丙酯(GMA)接枝的聚丙烯(PP-g-GMA)。化学滴定和红外光谱(FTIR)证明得到了PP-g-GMA产品。研究了引发剂、单体、反应温度、停留时间和助剂待因素对接枝率、接枝效率、熔体流动速率的影响。以苯乙烯作为助剂,接枝效率可以提高到80%。比较了PP-g-GMA与DSM公司提供的PP-g-GMA的力学性能。PP-g-GMA的抗张强度、杨氏模量、断裂伸长率和冲击强度都高于PP-g-MAH。研究并比较了PP-g-GMA和PP的热学性质。PP-g-GMA结晶度比PP增加,结晶温度提高,PP-g-GMA对Avrami方程有很大的偏差。制备了PA46/PP-g-GMA和PA46/PP共混物并对其力学性能、吸水率、形态结构、动态力学性质、热学性质等进行了研究。与PA46/PP相比,PA46/PP-g-GMA的抗张强度,杨氏模量,弯曲强度和弯曲模量都得到了提高。随着组成的变化,干态下PA46/PP-g-GMA的抗张强度分别比PA46/PP提高10%到35%,杨氏模量提高10%到30%,弯曲强度提高10%-200%,弯曲模量提高10%-50%。PA46/PP-g-GMA的吸水率大大低于PA46/PP,共混物组成为50/50时,PA46/PP的吸水率是PA46/PP-g-GMA的三倍多。扫描电镜(SEM)得到的PA46/PP及PA46/PP-g-GMA的拉伸和冲击断面形态显示,PP-g-GMA在PA46中的粒径尺寸大大变小,变均匀。动态热机械分析(DMA)、示差扫描量热仪(DSC),热失重分析(TGA)结果显示相同组分的PA/PP-g-GMA比PA46/PP的储能模量大,软化温度提高,组分为50/50时,PA46/PP-g-GMA比PA46/PP提高达120 ℃。在PA46/PP-g-GMA和PA46/PP共混体系中,由于两相之间的化学链接,使PP-g-GMA的熔融温度提高1-5 ℃,而PP的熔融温度降低1-7 ℃。相同组分的PA/PP-g-GMA和PA46/PP的热稳定性基本相同。

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本文分另研究了H[DEHP]从不同酸性介质中萃取稀土(III)(Sc、Y、Ho、Er、yb、Lu)及Fe(III)、Zn(II)的机理及性能。一、H[DEHP]从 H_2SO_4介质中萃取Sc(III)的机理 1. H[DEHP]萃取H_2SO_4及其机理 2. H[DEHP]萃取Sc(III)的机理,用斜率法和饱和法确定了H[DEHP]的正庚烷溶液从H_2SO_4溶液中萃取Sc_2(SO_4)_3的机理及萃合物组成。研究表明,H[DEHP]萃取Sc(III)在高、低两种酸度范围内存在着两种不同的萃取机理。二、H[DEHP]从HCl介质中萃取Ln(III)和Fe(III)的性能及H[DEHP]萃取Ln(III)的机理研究了H[DEHP]的正庚烷溶液从HCl介质中萃取稀土(III)(Sc、Y、Ho、Er、Yb、Lu)和Fe(III)的性能,得出H[DEHP]在相同条件下萃取以上各金属离子的顺序是:Sc(III)>Fe(III)>Lu(III)>Yb(III)>Er(III)>Y(III)>Ho(III), 并计算了各金属离子之间的分离因素(β)。文中还讨论了Sc(III)、Fe(III)、Lu(III)之间的分离以及重稀土离子间的萃取分离,同时与相同实验条件下HEH[EHP]的萃取性能进行了比较,为新的萃取体系提供了一些参数。三、H[DEHP]从不同介质中萃取Fe(III)的机理,研究了H[DEHP]的正率烷溶液从Hcl介质中和H[DEHP]的正庚烷溶液从H_2SO_4介质中萃取Fe(III)的平衡规律;用斜率法、饱和法以及IR和NMR谱等讨论了低酸度下的萃取机理。四、H[DEHP]萃取Zn(II)的机理,研究了H[DEHP]的正率烷溶液从Hcl介中萃取Zn(II)的平衡,利用斜率法、饱和法及SR、NMR谱等讨论了低Hcl浓度下的萃取机理。

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本工作以界面铺张一硝酸银染色技术,对小麂、黑麂和赤麂的精母细胞联会复合体(Synaptonemal Complex, SC)进行显微及亚显微结构比较研究。结果表明:1. 常染色体联会复合体的形成开始于偶线期,成熟于粗线期,消失于双线期。从早粗线期到晚粗线期,同一细胞内常染色体SC的长度同步缩短。SC的平均对长度和臂比指数同体细胞相应染色体的数值有很好的一致性。根据SC的平均相对长度和臂比指数绘制三种的SC组型模式图。小麂(M.reevesi)组型:2n = 46♀,♂,性别决定为XX/XY。赤麂(M.muntjak)组型:2n = 6♀,7♂;性别决定为XAXA/XAY,在雄性减数分裂前期 形成一个易位三价体,黑麂(M.Criniffrons)组型:2n = 8♀,9♂,性别快定为XAXA/XAY。雄恶性循环 黑麂核型的演化过程涉及两次染色体易位和一次臂间倒位,在减数分裂前期形成一个复杂的易位多价体。2. 在减数分裂前期,常染色体SC侧轴和X染色体轴有时呈双线结构。这表明,SC侧轴与有丝分裂染色体的“轴心”结构有一定的联系。3. 在减数分裂前期,性染色体的行为和形态同常染色体有明显差异,如嗜银性强,配对延迟等。XY的配对起始于早粗线期;在中粗线期,几乎Y染以体的全长均参与和X染色体配对;随着粗线期进一步发展,XY-SC渐渐解体;在双线期,X,Y完全分离。黑麂X、Y之间的配对,包含有Y染有体的着丝粒区域和X染色体的非着丝粒区域。这表明,X与Y的配对至少在局部区域是非同源性的。4. 在粗线期,X染色体未配对区域出现不同程度的自身折叠,形成“发夹”状结构。“发夹”结构的形成,可能是由于在性染色体的进化过程中,X染色体通过不对称易位得到的重复片段,在减分裂前期发生同源配对的一种细胞表现。

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Single-neutron-transfer measurements using (p,d) reactions have been performed at 33 MeV per nucleon with proton-rich Ar-34 and neutron-rich Ar-46 beams in inverse kinematics. The extracted spectroscopic factors are compared to the large-basis shell-model calculations. Relatively weak quenching of the spectroscopic factors is observed between Ar-34 and Ar-46. The experimental results suggest that neutron correlations have a weak dependence on the asymmetry of the nucleus over this isotopic region. The present results are consistent with the systematics established from extensive studies of spectroscopic factors and dispersive optical-model analyses of Ca40-49 isotopes. They are, however, inconsistent with the trends obtained in knockout-reaction measurements.

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用能量密度公式及小液滴模型给出的费米密度分布,并引入中子皮及中子分布弥散度随中子过剩自由度增加而增加这一因素,计算了重离子反应在相互作用势及熔合位垒。熔合位垒的计算值和实验值符合很好,特别是在中重核区域,改善了以前的计算结果。详细研究了亲近势标度,发现用中子皮及中子分布弥散度的变化能较好地解释中子过剩自由度对新近势标度偏离的影响。本工作对奇异核结构与核反应性质的研究无疑是有用的。我们利用HIRFL提供的46.7MeV/u ~(12)C束轰击~(58)Ni、~(115)In、~(197)Au研究了反应中发射的α粒子角分布和能谱。从速度表象中洛仑兹不变截面等高图中明显看到发射α粒子的三个源。用这三个源的运动模型成功拟合了α粒子能谱,所提取的参数符合费米气体模型计算结果,并讨论了能谱及拟合参数对靶的依赖关系。认为快速源实质上来自弹核碎裂或类弹核碎裂

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本文分析了翁牛特旗46年(1957-2002年)逐月降水量和平均气温。结果表明:气温呈非连续增暖趋势,其中年平均气温线性变化率为0.39℃.(10a)-1,年平均最高气温线性变化率为0.19℃.(10a)-1,年平均最低气温线性变化率为0.93℃.(10a)-1;最低气温上升速率是最高气温的1-4倍,气温日较差显著减小。上世纪60年代较50年代有所增暖,80年代后期开始明显升温,90年代是近50年来最暖的10年。1987年开始转暖,其后呈连续性增暖趋势,1998年为1957年以来的最暖年,年平均气温7.7℃,高于1957年2.9℃。降水以平均5-7年的周期变化,并从50年代到90年代呈连续性递减趋势,线性变化率为-11.7mm.(10a)-1,90年代较50年代年降水减少了39.4mm。

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The crystallization behaviors and morphology of asymmetric crystalline-crystalline diblock copolymers poly(ethylene oxide-lactide) (PEO-b-PLLA) were investigated using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and microscopic techniques (polarized optical microscopy (POM) and atomic force microscopy (AFM)). Both blocks of PEO5-b-PLLA(16) can be crystallized, which was confirmed by WAXD, while PEO block in PEO5-b-PLLA(30) is difficult to crystallize because of the confinement induced by the high glass transition temperature and crystallization of PLLA block with the microphase separation of the block copolymer.

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Molecular weight dependence of phase separation behavior of the Poly (ethylene oxide) (PEO)/Poly(ethylene oxide-block-dimethylsiloxane) (P(EO-b-DMS)) blends was investigated by both experimental and theoretical methods. The cloud point curves of PEO/P(EO-b-DMS) blends were obtained by turbidity method. Based on Sanchez-Lacombe lattice fluid theory (SLLFT), the adjustable parameter, epsilon*(12)/k (quantifying the interaction energy between different components), was evaluated by fitting the experimental data in phase diagrams. To calculate the spinodals, binodals, and the volume changes of mixing for these blends, three modified combining rules of the scaling parameters for the block copolymer were introduced.

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The syntheses of several dialkyl complexes based on rare-earth metal were described. Three beta-diimine compounds with varying N-aryl substituents (HL1 = (2-CH3O(C6H4))N=C(CH3)CH=C(CH3)NH(2-CH3O(C6H4)), HL2 = (2,4,6-(CH3)(3) (C6H2))N=C(CH3)CH=C(CH3)NH(2,4,6-(CH3)(3)(C6H2)), HL3 = PhN=C(CH3)CH(CH3) NHPh) were treated with Ln(CH2SiMe3)(3)(THF)(2) to give dialkyl complexes L(1)Ln (CH2SiMe3)(2) (Ln = Y (1a), Lu (1b), Sc (1c)), L(2)Ln(CH2SiMe3)(2)(THF) (Ln = Y (2a), Lu (2b)), and (LLu)-Lu-3(CH2SiMe3)(2)(THF) (3). All these complexes were applied to the copolymerization of cyclohexene oxide (CHO) and carbon dioxide as single-component catalysts.

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Reaction of 7-{(N-2,6-R)iminomethyl)}lindole (HL1, R = dimethylphenyl; HL2, R = diisopropylphenyl) and rare-earth metal tris(alkyl)s, Ln(CH2SiMe3)(3)(THF)(2), generated new rare-earth metal bis(alkyl) complexes LLn(CH2SiMe3)(2)(THF) [L = L-1: Ln = Lu. (1a), Sc (1b); L = L-2 : Ln = Lu (3a), Se (3b)] and mono(alkyl) complexes L-2 Lu-2(CH2SiMe3) (4a). Treatment of alkyl complexes 1a and 4a with N,N'-diisopropylcarbodiimide afforded the corresponding amidinates (LLu)-Lu-1{iPr(2)NC(CH2SiMe3) NiPr2}(2) (2a) and L-2 Lu-2{iPr(2)NC(CH2SiMe3)NiPr2} (5a), respectively.

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The present calculations were performed on the basis of the Sanchez-Lacombe lattice fluid theory and the new combinatorial rules for block copolymer according to the experimental results on the pressure-induced compatibility in poly(ethylene oxide) (PEO) and poly(ethylene oxide-b-dimethylsiloxane) (P(EO-b-DMS)) mixtures with UCST behavior. The study on enthalpy, combinatorial entropy, vacancy entropy and Gibbs energy upon mixture shows that Sanchez-Lacombe fluid theory and the new combinatorial rules could describe the pressure-induced compatibility (PIC) of polymer mixtures with UCST behavior well.