9 resultados para DTC pentafase
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
Thermal and crystalline properties of random copolymer of epsilon-caprolactone (CL) and 2,2-dimethyl trimethylene carbonate (DTC) prepared by lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) (La(OAr)(3)) have been investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and wide-angle X-ray diffraction (WAXD). Fox equation interprets the relationship between glass transition temperature (T-g) and copolymer compositions. T-g decreases from PDTC (16.7degreesC) to PCL (-65.1degreesC), reflecting the internal plasticizing effect of CL units on DTC units in the copolymers. The introduction of CL units to PDTC can effectively improve its heat resistance. Small amount of DTC (5% molar) in PCL chain improves the mechanical properties of the polymer, which had elongation of 1000, much higher than that of PCL (8.8).
Resumo:
合成了一种新型异核双金属离子对配合物[Mo(dtc)_4]·[Nd(dtc)_4],并通过X-射线衍射法和元素分析确定了其晶体结构和分子结构,在此基础上,经红外光潜分析确定了该配合物的谱学性质。
Resumo:
Six polymorphic microsatellites (eight loci) were used to study the genetic diversity and population structure of common carp from Dongting Lake (DTC), Poyang Lake (PYC), and the Yangtze River (YZC) in China. The gene diversity was high among populations with values close to 1. The number of alleles per locus ranged from 2 to 11, and the average number of alleles among 3 populations ranged from 6.5 to 7.9. The mean observed (H (O)) and expected (H (E)) heterozygosity ranged from 0.4888 to 0.5162 and from 0.7679 to 0.7708, respectively. Significant deviations from Hardy-Weinberg Equilibrium expectation were found at majority of the loci and in all three populations in which heterozygote deficits were apparent. The analysis of molecular variance (AMOVA) indicated that the percent of variance among populations and within populations were 3.03 and 96.97, respectively. The Fst values between populations indicated that there were significant genetic differentiations for the common carp populations from the Yangtze River and two largest Chinese freshwater lakes. The factors that may result in genetic divergence and significant reduction of the observed heterozygosity were discussed.
Resumo:
采用切线性模式和代码转换策略,开发了C语言自动微分转换系统(DTC),用于牛顿法求解非线性方程中Jacobi矩阵—向量乘积计算。介绍系统计算模型、功能、特色,并讨论系统的设计与实现技术,包括编译技术、微分代码转换及输入/输出(I/O)相关分析。最后给出了几个具有说服力的测试与应用。
Resumo:
大规模科学计算已经广泛应用在气象、海洋、化学、生物医药、电子工程等领域。科学计算软件的开发是科学计算的关键环节。开发一个具有良好可靠性的计算工具,并与大型计算工具箱集成而完成大规模、复杂实际问题的计算,具有重要意义。 PETSc(Portable, Extensible Toolkit for Scientific Computation)是国际流行的科学计算工具箱,它可用于偏微分方程的求解及相关的高性能计算问题。本文分析了PETSc的主要功能、结构与特色,并剖析了其核心组件,包括向量、矩阵、线性方程组求解器KSP、非线性求解器SNES等。 自动微分是计算函数导数的重要方法,它可以应用在最优化问题的实际计算中。在PETSc中提供了ADIC、ADIFOR等自动微分软件包的接口。本文分析了自动微分计算函数一阶导数的切线性模式与伴随模式的基本原理,介绍了现有的自动微分软件的情况,特别是ADIC的开发及其与PETSc的接口。 DTC(Differentiation Transforming System in C)是针对C语言自动微分工具,用于生成切线性模式。DTC生成的切线性代码可用于计算雅可比矩阵-向量乘积等。本文详细介绍了DTC系统的设计及关键技术,包括编译技术、输入/输出(IO)相关分析等。针对PETSc的复杂数据结构,开发了DTC与PETSc的接口,将两者集成,并应用在求解二维全球正压大气浅水波方程中。最后给出了DTC系统的相关测试结果。
Resumo:
本研究旨在利用突变后的血管内皮生长因子(VEGF)与白喉毒素(DT)构建靶向毒素,使其特异性地杀伤肿瘤血管,达到阻断血管增生,切断肿瘤的血液供应的目的。首先通过基因工程技术从白喉杆菌中提取基因组DNA,扩增出其中的DTC区、T区基因。并运用不同的突变方法,构建了四个VEGF的突变体。即VEGF R82A,K84A,H86A突变,VEGF D63A,E64A,E67A突变,和截去了肝素结合区和NP-l(neuropilin-l)受体结合区的VEGF R82A,K84A,H86A突变和VEGF D63A,E64A,E67A突变。以这些突变体的编码基因与DT的T区、C区基因制成四个融合基因,并在大肠杆菌中表达、纯化、复性。以相似条件下制备的不加VEGF突变体的DTT区、C区蛋白为阴性对照,以VEGFR-l+和VEGFR-2+的Lovo细胞和VEGFR-l+VEGFR-2-的SMMC-7721细胞做细胞实验。制成的四个融合毒素中有三个通过细胞学检验,具有靶向杀伤作用。特异性结合VEGFR-1受体的蛋白PmV8D、PsmVSD既可以抑制VEGFR-1+、VEGFR-2-的肝癌细胞SMMC-7721又可以抑制VEGFR-1+、VEGFR-2+的结肠癌细胞Lovo。而不带VEGF突变体的DT391无抑制作用。特异性结合VEGFRZ受体的蛋白PmV6D可以抑制VEGFR-1+、VEGFR-2+结肠癌细胞Lovo的生长,但不可以抑制VEGFR-1+,VEGFR-2-的肝癌细胞SMMC-7721。受体结合力过弱的PsmV6D不对细胞的生长产生任何影响。
Resumo:
A series of lutetium alkyl, amino, and guanidinato complexes based upon an amino-phosphine ligand framework had been prepared. These complexes were applied to initiate ring-opening polymerization of 2,2'-dimethyltrimethylene carbonate (DTC). The type of the initiator significantly influenced the catalytic activity of these complexes in a trend as follows: alkyl approximate to guanidinate > amide, whereas the complexes with flexible backbone between P and N atoms within the ligand exhibited higher activity than those with rigid backbone. The isolated PDTC had bimodal-mode molecular weight distribution. The molecular weights of each fraction increased linearly with the conversion, indicating that there might be two active species. This had been confirmed by analyses of oligomeric DTC living species and oligomer with NMR technique as the metal-alkoxide and the four-membered metallocyclic lactate. Kinetic investigation displayed that the polymerization rate was the first order with the monomer concentration.
Resumo:
One mu-dichloro bridged diiridium complex and three mononuclear iridium(III) complexes based on the 1,3,4-oxadiazole derivatives as cyclometalated ligands and acetylacetonate (acac) or dithiolates O,O'-diethyldithiophosphate (Et(2)dtp) or N,N'-diethyldithiocarbamate (Et(2)dtc) as ancillary ligands have been synthesized and systematically studied by X-ray diffraction analysis. The results reveal that three mononuclear complexes all adopt distorted octahedral coordination geometry around the iridium center by two chelating ligands with cis-C-C and trans-N-N dispositions, which have the same coordination mode as the diiridium dimer. The dinuclear complex crystallizes in the monoclinic system and space group C2/c, whereas three mononuclear iridium complexes are all triclinic system and space group P(1) over bar. In the stacking structure of the dimer, one-dimensional tape-like chains along the b-axis are formed by hydrogen bondings, which are strengthened by pi stacking interactions between phenyl rings of 1,3,4-oxadiazole ligands. Then these chains assemble a three-dimensional alternating peak and valley fused wave-shape structure. In each stacking structure of three mononuclear complexes, two molecules form a dimer by the C-H center dot center dot center dot O hydrogen bondings, and these dimers are connected by pi stacking interactions along the b-axis, constructing a zigzag chain.
Resumo:
A series of novel iridium(III) complexes with two 2-arylquinoline derivatives as cyclometalated ligands and one monoanionic ligand, such as acetylacetonate (acac), N,N'-diethyldithiocarbamate (Et(2)dtc) and O,O'-diethyldithiophosphate (Et(2)dtp), as ancillary ligands have been synthesized and structurally characterized by H-1 NMR, MS and elemental analysis (EA). The cyclic voltammetry, absorption, emission and electroluminescence properties of these complexes were systematically investigated. Through extending pi-conjugation, introducing electron-donating groups in the ligand frame, or changing the ancillary ligands, the HOMO energy levels of the iridium(III) complexes can be tuned, while their LUMO levels remain little affected; in consequence, the emission wavelengths of the iridium(III) complexes can be tuned in the range 606-653 nm. The highly efficient organic light-emitting diodes (OLEDs) with saturated red emission have been demonstrated. A maximum current efficiency of 10.79 cd A(-1), at a current density of 0.74 mA cm(-2), with an emission wavelength of 616 nm and Commisioon Internationale de L'Eclairage (CIE) coordinates of (0.65, 0.35), which are very close to the National Television System Comittee (NSTC) standard red emission, have been achieved when using complex (DPQ)(2)Ir(acac) as a phosphor dopant.