The Homology and Relationship of Human (Homo sapiens) Chromosomes 1, 19 and Dusky Langur (Trachypithacus obscurus) Chromosomes 6, 8 Demonstrated with Chromosome Painting

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Analysis of the energies of the triple base triplets

Sixty-four sets of three-dimensional models of DNA triplex base triplets (TBT) were built up based on codons by homologous modeling method and their energies were minimized. According to sequence of TBT and orientation of the third ODN strand third, the energies of monomers and water-K+-TBT ternary complexes of TBT were analyzed. The results showed: (i) The energies of the symmetric parallel monomers are generally lower than those of the symmetric anti-parallel monomers of TBT, but the energies of the symmetric parallel ternary complexes are higher than those of the symmetric anti-parallel ternary complexes of TBT. (ii) No matter TBTs are monomers or ternary complexes, the energies of asymmetric parallel TBTs are generally lower than those of the asymmetric anti-parallel ones. (iii) Although the energies of the parallel TBTs are correlated with those of the anti-parallel ones, the energy differences are significant between them. The results here suggest the sequences of TBTs and the orientations of the third ODN strands are two of the key factors that can influence the formation and stability of TBT. (C) 2002 Elsevier Science B.V. All rights reserved.

The comparative analysis of the energies of conjugated triple base triplets and their applications

We built 64 sets of 3D models of DNA triplex base triplets (TBT) and minimized their energies. The TBTs were divided into 32 pairs of conjugated ones on the basis of their sequence characteristic, and the energies of each pair of them were compared and analyzed, the results showed: (i) The duplex DNA of which any strand contains at least a couple of A or T, has a preference for selecting the oligodeoxyribonucleic acid (ODN) strand containing abundant T to form TBT. (ii) The duplex DNA of which any strand contains at least a couple of G or C has a preference for selecting ODN containing abundant G to form symmetric antiparallel TBT, but selecting ODN containing abundant C to form asymmetric parallel TBT. (iii) The duplex DNA of which any strand contains only one of A, T, G or C has a preference for selecting ODN containing abundant pyrimidines (T or C) to form antiparallel TBT. Additionally, two examples of TBTs applications, in designing ODN to form triplex with duplex were presented. The energy calculation result revealed that 15-TCG is the best ligand of the HIV PPT duplex. The comparative analysis of energies of the conjugated TBTs provides directive significance for designing ODN strand that is easy to form triplex in theory. (C) 2002 Elsevier Science B.V. All rights reserved.

Sixfold symmetry of excitonic transition energies in c-plane for wurtzite GaN

The optical properties of the strained wurtzite GaN are investigated theoretically within the nearest neighbor tight-binding method. The piezoelectric effect is also taken into account. The empirical rule has been used in the strained band-structure calculation. The results show that the excitonic transition energies are anisotropic in the c-plane in a high electronic concentration system and have a 60 degrees periodicity, which is in agreement with experiment. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3001937]

Energy bands and acceptor binding energies of GaN

The energy bands of zinc-blende and wurtzite GaN are calculated with the empirical pseudopotential method, and the pseudopotential parameters for Ga and N atoms are-given. The calculated energy bands are in agreement with those obtained by the ab initio method. The effective-mass theory for the semiconductors of wurtzite structure is established, and the effective-mass parameters of GaN for both structures are given The binding energies of acceptor states are calculated by solving strictly the effective-mass equations. The binding energies of donor and acceptor are 24 and 142 meV for the zinc-blende structure, 20 and 131, and 97 meV for the wurtzite structure, respectively, which are consistent with recent experimental results. It is proposed that there are two kinds of acceptor in wurtzite GaN. One kind is the general acceptor such as C, which substitutes N, which satisfies the effective-mass theory. The other kind of acceptor includes Mg, Zn, Cd, etc., the binding energy of these accepters is deviated from that given by the effective mass theory. In this report, wurtzite GaN is grown by the molecular-beam epitaxy method, and the photoluminescence spectra were measured. Three main peaks are assigned to the donor-acceptor transitions from two kinds of accepters. Some of the transitions were identified as coming from the cubic phase of GaN, which appears randomly within the predominantly hexagonal material. [S0163-1829(99)15915-0].

Tuning the Exciton Binding Energies in Single Self-Assembled InGaAs/GaAs Quantum Dots by Piezoelectric-Induced Biaxial Stress

We study the effect of an external biaxial stress on the light emission of single InGaAs/GaAs(001) quantum dots placed onto piezoelectric actuators. With increasing compression, the emission blueshifts and the binding energies of the positive trion (X+) and biexciton (XX) relative to the neutral exciton (X) show a monotonic increase. This phenomenon is mainly ascribed to changes in electron and hole localization and it provides a robust method to achieve color coincidence in the emission of X and XX, which is a prerequisite for the possible generation of entangled photon pairs via the recently proposed "time reordering'' scheme.

聚芴及其衍生物电致发光材料的合成与表征

本论文以合成聚荀及其衍生物电致发光材料为目的。通过光谱性质、电化学性质的表征及聚合物单层电致发光器件的测试来评价所合成的聚合物的性能。经过研究不同分子结构的共聚合单体及其含量对聚合物光电性能的影响及相关机理，为设计高性能的电致发光聚合物材料探索切实可行的途径。1．设计并合成了在侧链中带有嗯二哇类电子注入和传输基团的聚（9，9-二烷芴）系列聚合物，详细讨论了嗯二哇侧基含量对聚合物的分子量、溶解性、热性能的影响。嗯二哇侧基使聚合物有较大的空间位阻，限制了聚（9，9-二烷芴）的分子间的堆积，破坏了其晶相的形成。由于不同含量的唔二哇的引入，提高了聚合物的LUMO值，降低了电子的注入势垒。聚合物单层电致发光器件的性能数据表明，嗯二哇侧基的引入可以提高器件的效率和亮度，且含嗯二哇侧基的单体含量的最佳范围为27％左右。嗯二哇侧基的加入，导致电致发光出现较强的激基复合物发光，器件的电致发光表现为蓝白色荧光。2．设计和合成了在侧链中带有三苯胺基团的芴类系列聚合物，详细讨论了三苯胺侧基对聚合物的分子量、溶解性、热性能进行的影响。三苯胺侧基使聚合物有较大的位阻，限制了聚合物分子间的堆积，破坏了晶相的形成。三苯胺的引入降低了聚合物的HOMO值，因此空穴的注入势垒较小。聚合物单层电致发光器件的研究结果表明，三苯胺侧基的引入可以提高器件的效率和亮度，且三苯胺侧基的单体的含量的最佳范围为13％左右。加入三苯胺侧基后，聚合物保持了聚药本身的蓝光发光特性，并在一定程度上可以抑制激基复合物的形成。3．设计并合成了一类新的N-苯基取代吩噬嗦与9，9-二烷芴的具有空穴注入和传输功能的共聚物发光材料。N一苯基取代的吩唆嗓使聚合物发光有较大的红移，且光谱变宽。N-苯基取代的吩唆嗦与9，9-二烷芴交替共聚物显示出比三苯胺和咔哇类单体与9，9-二烷芴交替共聚物更低的HOMO值，是一类潜在的空穴注入和传输材料。在共聚含量低于30％时，吩噬啧单体的引入可以提高器件的效率。其电致发光光谱显示出与光致发光光谱相同的变化规律。4．本章基于“蓝光和橙光二原色”协同形成白光的物理思想，采用聚芴为蓝光构造基元，蔡酞亚胺衍生物为橙光构造基元，设计合成了将蔡酞亚胺衍生物共聚到聚荀及其衍生物主链的系列聚合物，实现蓝光和橙光发射基元在单一高分子中共同发光。通过调节蔡酰亚胺衍生物单体的含量，调控蓝光发射与橙光发射的相对强度，实现单一高分子的白光发射。利用能量转移和电荷转移（或电荷捕获）提高了聚合物器件性能，来达到提高白光器件电致发光光谱稳定性的目的。本章制备的白色电荧光聚合物是目前世界上器件结构和制备工艺最简单，效率最高的白光电致发光聚合物材料。