Generation of picosecond pulses with a repetition frequency of 100 GHz by a multicomponent injection laser

A mode for generating a sequence of spectrally limited pulses with a duration of 2 nsec and a repetition frequency of approximately 100 GHz in AlGaAs/GaAs by an injection heterolaser, which has amplifying and absorbing parts combined in a common resonator, is discussed.

Characteristics of the spectral dynamics of picosecond modulated AlGaAs/GaAs injection lasers

Breakdown of the optical spectrum of a train of picosecond pulses into components with a distance which exceeds kT (200 cm-1 at λ = 955 nm and T = 300 K) is discovered for the first time in an injection laser. The effect may be caused by combined interaction between photons and phonons, with collective excitations in the degraded electron-hole GaAs plasma, and with the stream of drifting carriers in the active medium of the laser.

有机化合物结构解析专家系统研究——空间立体异构体的穷举生成

有机化合物结构解析专家系统的研究一直是计算机化学领域的前沿课题。本文在ESESOC 系统已有的基础上，进行了空间立体异构体的结构穷举生成研究，可以从化合物的二维连接表出发，穷举生成出全部的立体异构体。立体异构体的穷举生成需要满足三个条件：穷举性、非冗余性和有效性。目前本系统对于含 C、N、P、S与Si 等元素由于不对称中心、不对称轴引起的立体异构和几何异构均能进行穷举生成。本系统得到的结果与著名的 DENDRAL 系统和 SEMSMI 系统的结果完全一致。而 DENDRAL 系统已经从理论上证明是正确的。关于效率问题，通过对自同构群算法的改进，本系统的生成速度快于SEMAMI系统（其它系统运行时间未见报道），完全能够满足实验室应用。结构解析系统中环的识别主要是所有环的识别以及SSSR（最小的小最环集合）的识别，通过图论算法的应用，本文对这几类环的识别算法都进行了探讨，并应用于 ESESOC 系统作为约束条件，大大减少了系统候选化合物的数目。芳香性的识别，特别是稠环化合物芳香性的识别，在结构解析专家系统中一直是很难解决的问题，主要是稠环芳香性化合物的共振式比较多，而且在结构解析系统中得到的哪种共振式事先并不能确知，本文对各类常见的芳香性进行了自动识别的研究，并应用于 ESESOC系统中，取得了良好的结果。

分子中芳香性自动识别算法

以图论为基础,从化合物的二维连接表出发,在环识别算法的约束下,对分子中的节点进行判断．结果表明,该算法能够识别大多数化合物中的芳香性．作为约束条件,把芳香性的识别算法应用于ＥＳＥＳＯＣ系统中结构的穷举生成,得到了较好的结果．

The algorithm on ring perception of molecule

It's important to identify ring in the process of structure elucidation. In this paper, all rings and the smallest set of smallest ring(SSSR) of structure are obtained from two-dimensional connection table. The results are satisfactory by using this algorithm in ESESOC expert system as constraint.

The Tamaricetea arceuthoidis: a new class for the continental riparian thickets of the Middle East, Central Asia and the subarid regions of the Lower Volga valley

The new class, the Tamaricetea arceuthoidis, is described covering riparian and intermittent shrubby vegetation of the Irano-Turanian Region in the southwestern and Central Asia and the Lower Volga valley. The dominating species are species of the genus Tamarix that refer high water table in arid and semi-arid habitats with high to moderate salinity. This new class is an ecological analogon of the Nerio-Tamaricetea occurring in the Mediterranean Basin.

Molecular modeling of N-terminal domains of NMDA-receptor. Study of ligand binding with N-terminal domains

Using the molecular-graphic complex Sybyl6.7.2, computational construction of spatial models for N-terminal domains (of NR1- and NR2B-subunits) of NMDA-receptor was conducted. On the basis of the constructed models and also CoMFA method the conclusion is made about presence of the binding site for the compounds similar to iphenprodyl in two N-terminal domains of NR1- and NR2B-subunits. The obtained data can be used for constructing new ligands.

Binding site of AMPA-receptor allosteric modulator

The computer molecular docking of piperonyl acid piperidide (BDP) and some its analogs already known as ampakins was conducted for estimating their possible binding with AMPA-receptor glutamate domains in cyclothiazide binding area and for further design of new structures maximally complimentary to the receptor. On the base of the conducted docking it can be suggested that the binding site of BDP (amides of benzodioxane-6-carboxylic and piperonyl acids) analogs is located in AMPA-receptor cyclothiazide binding pocket. It is shown that formation of protein-ligand complexes of AMPA-receptor with benzodioxane-6-carboxylic and piperonyl acid derivatives, similarly to cyclothiazide, proceeds with interaction with Ser497, Leu751, which significance is confirmed by site-specific mutagenesis.

Numerical model of solid phase transformations governed by nucleation and growth: microstructure development during isothermal crystallization

A simple numerical model which calculates the kinetics of crystallization involving randomly distributed nucleation and isotropic growth is presented. The model can be applied to different thermal histories and no restrictions are imposed on the time and the temperature dependences of the nucleation and growth rates. We also develop an algorithm which evaluates the corresponding emerging grain-size distribution. The algorithm is easy to implement and particularly flexible, making it possible to simulate several experimental conditions. Its simplicity and minimal computer requirements allow high accuracy for two- and three-dimensional growth simulations. The algorithm is applied to explore the grain morphology development during isothermal treatments for several nucleation regimes. In particular, thermal nucleation, preexisting nuclei, and the combination of both nucleation mechanisms are analyzed. For the first two cases, the universal grain-size distribution is obtained. The high accuracy of the model is stated from its comparison to analytical predictions. Finally, the validity of the Kolmogorov-Johnson-Mehl-Avrami model SSSR, is verified for all the cases studied