Structure of N-tert-butyloxycarbonyl-[alpha]-aminoisobutyryl-DL-pipecolyl-[alpha]-aminoisobutyric acid methyl ester

C20H35N3O6 (Boc-Aib-DL-Pip-Aib-OMe, Boc = tert-butyloxycarbonyl, Aib = alpha-aminoisobutyric acid, Pip = pipecolic acid, OMe = methoxy), M(r) = 413.5, monoclinic, P2(1)/c, a = 18.055 (3), b = 15.048 (3), c = 17.173 (3) angstrom, beta = 91.7 (1)-degrees, V = 4663.8 (9) angstrom3, Z = 8, D(m) = 1.16, D(x) = 1.178 Mg m-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu = 0.081 mm-1, F(000) = 1792, T = 297 K. The final R value for 4925 [I greater-than-or-equal-to 3sigma(I)] reflections is 0.065 (wR = 0.067). The peptide backbone of the two independent molecules in the asymmetric unit is folded at the -Aib-Pip- sequence to form a type-I (I') beta-bend stabilized by a 1 <-- 4 intramolecular N-H...O=C hydrogen bond between the Aib(3) peptide N-H and Boc urethane C=O groups.

Dielectric relaxation and anti-ferromagnetic coupling of BiEu03 and BiGd03

BiEuO3 (BE) and BiGdO3 (BG) are synthesized by the solid-state reaction technique. Rietveld refinement of the X-ray diffraction data shows that the samples are crystallized in cubic phase at room temperature having Fm3m symmetry with the lattice parameters of 5.4925(2) and 5.4712(2) A for BE and BG, respectively. Raman spectra of the samples are investigated to obtain the phonon modes of the samples. The dielectric properties of the samples are investigated in the frequency range from 42 Hz to 1.1 MHz and in the temperature range from 303 K to 673 K. An analysis of the real and imaginary parts of impedance is performed assuming a distribution of relaxation times as confirmed by the Cole-Cole plots. The frequency-dependent maxima in the loss tangent are found to obey an Arrhenius law with activation energy similar to 1 eV for both the samples. The frequency-dependent electrical data are also analyzed in the framework of conductivity formalism. Magnetization of the samples are measured under the field cooled (EC) and zero field cooled (ZFC) modes in the temperature range from 5 K to 300 K applying a magnetic Field of 500 Oe. The FC and ZFC susceptibilities show that BE is a Van Vleck paramagnetic material with antiferromagnetic coupling at low temperature whereas BG is an anti-ferromagnetic system. The results are substantiated by the M-11 loops of the materials taken at 5 K in the ZFC mode. (C) 2014 Elsevier B.V. All rights reserved

Educação física e esporte escolar : da formação à competição

Seminário de Educação Física e Esporte promovido pela Comissão de Turismo e Desporto no qual foram foram debatidos os seguintes temas: a importância da educação física no sistema educacional brasileiro; o desenvolvimento cognitivo e motor e sua relação com a implementação da educação física no sistema no ensino infantil; as experiências exitosas em educação através do esporte; programas de inspiração internacional; a organização dos jogos e competições escolares como fator de democratização da prática esportiva e a relação dos jogos escolares com a prática da educação física e a seleção de atletas de alto rendimento.

The annular crack in a nonhomogeneous matrix surrounding a fiber under torsional loading .2. The crack going through the bimaterial interface into the fiber

The axisymmetric problem of an elastic fiber perfectly bonded to a nonhomogeneous elastic matrix which contains an annular crack going through the interface into the fiber under axially symmetric shear stress is considered. The nature of the stress singularity is studied. It is shown that at the irregular point on the interface, whether the shear modulus is continuous or discontinuous the stresses are bounded. The problem is formulated in terms of a singular integral equation and can be solved by a regular method. The stress intensity factors and crack surface displacement are given.

Preliminary surveys of the fish and fisheries of the Nzoia, Nyando and Sondu Miriu rivers, Kenya

Three Lake Victoria rivers were sampled to assess fish abundance and distribution in preparation for assessment of catches from the river systems. Preliminary fish abundance data indicate that fishing potential upstream is negligible but that important commercial species are present in the downstream floodplain areas. Three catfish species were recorded in the Nzoia river system that have not been found previously in the Kenyan sector of the Lake Victoria system, together with possibly two undescribed Barbus species.

Broadband near-infrared emission from transparent Ni2+-doped silicate glass ceramics

Transparent Ni2+-doped MgO-Al2O3-TiO2-SiO2 glass ceramics were prepared, and the optical properties of Ni2+-doped glass ceramics were investigated. Broadband emission centered at 1320 nm was observed by 980 nm excitation. The longer wavelength luminescence compared with Ni2+-doped Li2O-Ga2O3-SiO2 glass ceramics is ascribed to the low crystal field hold by Ni2+ in MgO-Al2O3-TiO2-SiO2 glass ceramics. The change in optical signals at the telecommunication bands with or without 980 nm excitation was also measured when the seed beam passes through the bulk gain host.(C) 2007 American Institute of Physics.

基底微缺陷对介质薄膜光学性能影响的理论研究

基于非均匀膜理论提出一种存在微缺陷的介质基底的折射率分层模型，将基底依次分为表面层、亚表面层和体材料层，其中表面层和亚面层分别等效为折射率服从统计分布的非均匀膜，将它们分别再次细分为N1和N2个子层，每一子层均视为均匀介质膜．应用光学薄膜特征矩阵法对其进行理论分析，并对单层介质膜的光学性能进行数值计算．研究结果表明：基底的表面和亚表面微缺陷改变了薄膜和基底的等效折射率，导致了准Brewster角和组合反射率与理想情形的偏离．同时这些微缺陷也改变了光在薄膜和基底中的传播特性，因此反射相移和相位差均偏离理想情

Phylogeny of fireflies (Coleoptera : Lampyridae) inferred from mitochondrial 16S ribosomal DNA, with references to morphological and ethological traits

We sequenced partial mitochondrial 16S ribosomal DNA (16S rDNA) of 18 firefly species from Southwest of China. Combined with homologous sequences previously reported, phylogenetic trees including Japanese, Korean and Chinese species were reconstructed by

自组织InAlAs/AlGaAs红光量子点材料生长及其性质研究

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

离子束诱变技术及其在甜高粱能源开发中的应用

利用离子束诱变技术进行甜高粱品种和酵母菌种的选育,旨在甜高粱燃料乙醇产业化的有效开发。对离子束诱变技术的原理及其在植物、微生物诱变育种方面的应用进展进行了简要概述,并对中科院近代物理研究所在甜高粱燃料乙醇产业化研发中对重离子诱变育种的初步应用进行介绍和展望。

25MeV/u~(40)Ar+~(115)In反应碎片和轻带电粒子的方位角关联

在２５ＭｅＶ／ｕ４０Ａｒ＋１１５Ｉｎ反应的在平面和出平面大角度关联测量中，提取了碎片和α粒子之间的方位角关联函数和方位角非对称性因子．φ＝９０时，方位角关联函数呈现为最小值，表明在集体类转动效应影响下，反应产生的轻带电粒子和碎片优先在反应平面内发射．随着关联对质量的增加，在平面关联粒子的发射相对于束流轴不对称性逐渐增大．随着关联对质量的增加，相继衰变和粒子末态相互作用对φ＝０的关联粒子对方位角关联函数值的影响逐渐降低并直至消失，同时集体转动效应增强，方位角非对称性增加．