红雁池水库东方欧鳊Abramis brama orientalis Berg形态—生态学特征的研究

本文报导了东方欧鳊Abramis brama orientalis Berg从原产地前苏联咸海经额尔齐斯河引种到新疆乌鲁木齐红雁池水库后,其形态—生态学特征的研究。研究结果表明,红雁池水库亦具有适宜东方欧鳊生长繁殖的自然条件,东方欧鳊可作为一重要经济鱼类有计划地进行推广养殖。     

东方欧鳊（Abramis brama orientalis Berg）胚胎发育的初步观察

本文报导了东方欧(鱼扁)(Abramis broma Orientalis Berg)在新疆小水域条件下胚胎发育的初步观察结果,东方欧(鱼扁)是近数十年内才由苏联引进的鱼类,目前已成为新疆的主要经济鱼种,并已引种到北京、上海等十余省市,对其胚胎发育情况及所要求的条件,尽管苏联学者已做了不少工作,但在新的水域,特别是在人工孵化条件下的胚胎发育的情况,是渔业部门急待需要了解的问题.     

Simultaneous quantification of six phenylethanoid glycosides in some Turkish Scutellaria species by a new HPLC-DAD method

A new HPLC-DAD method was developed and validated for simultaneous determination of six main phenylethanoid glycosides (calceolarioside D, neocalceolarioside D, verbascoside, isoverbascoside, leucoseptoside A and martynoside) in the aerial parts of four Scutellaria L. taxa from flora of Turkey. All standard compounds showed a good linearity (R ² > 0.999) in a relatively wide concentration range (1–120 μg/mL). The LOD of the compounds was in the range of 0.104–1.295 μg/mL and the LOQ was in the range of 0.450–2.536 μg/mL. The recoveries of the selected compounds were calculated in the range of 97.46–117.85%. The amounts of the phenylethanoid glycosides showed variation in the extracts. The developed method was found to be accurate, precise and reproducible, and successfully applied to identify and quantify the phenylethanoid glycoside composition of Scutellaria species.     

Constituents of Fruit Bodies of Tramete orientalis

A known sterol, 5α,6α-epoxy-5α-crgosta-8(14),22E-diene-3β,7α-diol ( 1 ), and two new sterols, 5α,6α-epoxy-3β,8β,14α-trihydroxy-5α-ergost-22E-en-7-one ( 2 ), (3α,5α),(8β,11β)-diepidioxy-ergost-22E-en-12-one ( 3 ), were isolated and characterized from dried fruit bodies of Trametes orientalis. Their structures were elucidated according to spectral methods.     

Improving the accuracy of the spatial discretization in finite-difference electrochemical kinetic simulations, by means of the extended Numerov method

The fourth-order accurate, three-point finite-difference Numerov spatial discretization provides accurate and efficient solutions to the time-dependent governing differential equations of electrochemical kinetics in one-dimensional space geometry, when the equations contain first time derivatives of the solution, second spatial derivatives, and homogeneous reaction terms only. However, the original Numerov discretization is not applicable when the governing equations involve first spatial derivative terms. To overcome this limitation, an appropriately extended Numerov discretization is required. We examine the utility of one of such extensions, first described by Chawla. Relevant discrete formulae are outlined for systems of linear governing equations involving first derivative terms, and applied to five representative example models of electrochemical transient experiments. The extended Numerov discretization proves to have an accuracy and efficiency comparable to the original Numerov scheme, and its accuracy is typically up to four orders of magnitude higher, compared to the conventional, second-order accurate spatial discretization, commonly used in electrochemistry. This results in a considerable improvement of efficiency. Therefore, the application of the extended Numerov discretization to the electrochemical kinetic simulations can be fully recommended.     

Application of acidic extract of Platanus orientalis tree leaves as a green reagent for selective spectrophotometric determination of zirconium

Abstract

A novel spectrophotometric method for the determination of zirconium by using a new reagent, acidic extract of Platanus orientalis tree leaves is developed. In 6 M hydrochloric acid, zirconium reacts with this reagent to form a yellow product. The formed product shows maximum absorbance at 422 nm with a molar absorptivity value of 0.59×10^? l mol^?1 cm^?1 and the method was linear in the 0.4–8 µg mL^?1 concentration range. The detection limit value was found to be 0.086 µg mL^?1. The proposed method was simple, clean, low cost, selective, and sensitive. It was applied to the determination of zirconium in tap water, wastewater and well water samples with relative standard error of less than 2.5%.     

Theoretical and numerical analysis of coherent Smith-Purcell radiation

Coherent enhancement of Smith-Purcell radiation has attracted people's attention not only in adopting a better source but also in beam diagnostics aspect. In this paper, we study the intrinsic mechanism of coherent Smith-Purcell radiation on the basis of the van den Berg model. The emitted power of Smith-Purcell radiation is determined by the bunch profile in transverse and longitudinal directions. For short bunch whose longitudinal pulse length is comparable with the radiation wavelength, it can be concluded approximately that the power is proportional to the square number of electrons per bunch.     

利用傅里叶变换研究侧柏细胞排列

利用傅傅里叶变换图像处理技术来测定针叶材侧柏横切面早材细胞排列,把表示每一个细胞的半径为十个像素点的恻盘点图,进行傅里叶变换,再做能量光谱图的角度分布图,其最大值表示细胞的排列.通过傅里叶变换图像处理发现侧柏的细胞在斜向上的排列为15°.木材细胞排列参数为数字化识别木材提供了新依据,也为进一步分析其物理力学性质提供新的理论研究方向.     

A furostanol saponin and phytoecdysteroid from roots of <Emphasis Type="Italic">Helleborus orientalis</Emphasis>

A furostanol saponin mixture and a known phytoecdysteroid were isolated from the roots of Helleborus orientalis Lam. Their structures were established as 26-[(β-D-glucopyranosyl)oxy]-22α-hidroxyfurosta-5,25(27)-dien-1β,3β,11α-triol (1a), 26-[(β-D-glucopyranosyl)oxy]-22α-methoxyfurosta-5,25(27)-dien-1β,3β,11α-triol (1b), and 20-hydroxy-β-ecdyson-3-O-β-D-glycoside (2). Acid hydrolysis of 1a,b gave (1β,3β,11α,22α)-22,26-dimethoxyfurosta-5,25(27)-dien-1,3,11-triol (aglycone 1) and of 2 gave 20-hydroxy-β-ecdyson (aglycone 2). Their structures were elucidated by spectral analysis. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 75–77, January–February, 2007.     

Formation mechanism of InxGa1−xAs bridge layers on patterned GaAs substrates

The formation mechanism of In_xGa_1−xAs (x=0.06) bridge layers on patterned GaAs (1 1 1)B substrates using liquid-phase epitaxy has been investigated. For this (i) the effect of density gradient in the solution on the formation of bridge layer and (ii) growth of bridge layer on 1 1 0 line-seed-substrates were studied. The convection induced by destabilizing density gradient in the solution led to an increase of lateral growth rate of the InGaAs bridge layers on a substrate mounted on the upper portion of the solution. However, it did not have any significant effect on the formation of the bridge layers. The formation of bridge layer on 1 1 0 line-seed-substrate took place only for the {1 1 1}B growth fronts, which indicated that “Berg effect” is responsible for the formation of bridge layers.