Signal Substances and their Reception in the Sexual Cycle of Marine Brown Algae

Attraction and repulsion are responses to chemical stimuli which can be received and processed even by unicellular organisms without a morphologically defined nervous system. Chemical substances trigger off a chain of events which starts with a membrane-bound signal receptor and, after a sequence of regulatory and modulatory steps, ends in the modulation of a motor effector organ. Binding of the signal substances to the receptor produces conformational changes in which the receptor subunits are mutually dependent on one another, and also leads to chemical modification of the subunits and affects their molecular activity. These interactions, together with the characteristic type of movement, result in a physiological pattern of behavior which enables the flagellated sex cells (gametes) of marine brown algae to finally locate their partners. The simple but highly specific brown algae gamete systems have been investigated structurally and their biological activity analyzed. The signal substances are mainly highly unsaturated aliphatic or cyclic hydrocarbons with unsaturated side chains (general formula e. g. C₁₁H₁₄, C₁₁H₁₆, C₁₁H₁₈). These systems also serve as a simplifying model which helps in the understanding of complex ganglionic pathways in higher living organisms where the sense organs convey information from the surroundings to the central nervous system through nerve pathways. The information is then processed and answered, via efferent pathways, as movement.     

带干扰的两险种复合Poisson-geometric风险模型的破产概率

将经典单一型复合Poisson风险模型推广到带干扰的两险种复合Poisson-geometric过程.构造调节系数方程并证明了调节系数的存在唯一性之后,运用鞅方法推导出了该风险模型下保险公司破产概率的表达式和破产概率上界,并给出了当个体理赔额服从指数分布时破产概率的表达式.     

褐色脂肪组织中的解偶联蛋白

褐色脂肪组织的调节产热等方面的功能近年来一直倍受关注,尤其是存在其中的解偶联蛋白更是近年来研究的热点,本文概述了解偶联蛋白及其基因的结构、解偶联蛋白的生理作用。     

10β‐Acetoxy‐8α,9α‐epoxy‐14β‐hydroxy‐7‐oxodolastane – A New Diterpene Isolated from the Brazilian Brown Macroalga Canistrocarpus cervicornis

Chemical investigation on the nonpolar extract of the Brazilian brown alga Canistrocarpus cervicornis (Dictyotaceae) has led to the isolation of a new diterpene 1 and four known seco‐dolastane diterpenes 2 – 5 . Their chemical structures were elucidated by 1D‐ and 2D‐NMR spectroscopy, and the data was compared with the literature. A full X‐ray diffraction analysis confirmed the absolute configuration of 1 .     

On Perfectly Generating Projective Classes in Triangulated Categories

We say that a projective class in a triangulated category with coproducts is perfect if the corresponding ideal is closed under coproducts of maps. We study perfect projective classes and the associated phantom and cellular towers. Given a perfect generating projective class, we show that every object is isomorphic to the homotopy colimit of a cellular tower associated to that object. Using this result and the Neeman's Freyd-style representability theorem, we give a new proof of Brown Representability Theorem.     

Isolation of fucoxanthin from edible brown algae by microwave-assisted extraction coupled with high-speed countercurrent chromatography

A rapid and efficient method for the separation and purification of fucoxanthin from edible brown algae by microwave-assisted extraction coupled with high-speed countercurrent chromatography was developed. The algae were first extracted using microwave-assisted extraction, then the dried extract was dissolved and directly introduced into the high-speed countercurrent chromatography system with a two-phase solvent system consisting of hexane-ethyl acetate-ethanol-water (5:5:6:4, v/v/v/v). The isolation was done in less than 75 min, and a total of 0.83 mg, 1.09 mg, and 0.20 mg fucoxanthin were obtained from 25.0 g fresh Laminaria japonica Aresch, 1.5 g dry Undaria pinnatifida (Harv) Sur, and 15.0 g dry Sargassum fusiforme (Harv) Setch, respectively. The purity of fucoxanthin determined by HPLC was over 90% and its structure was further identified by LC-ESI-MS and (1) H-NMR.     

和田玉糖玉的致色机理研究

采用X射线粉晶衍射(XRD)、 激光剥蚀等离子体质谱(ICP-MS)、 拉曼光谱(RAMAN)和高分辨率透射电子显微镜(HRTEM)对和田玉糖玉的致色机理进行研究。结果显示,糖玉的主要矿物成分为透闪石,化学成分中的Fe含量和糖玉黄褐色色调有正相关关系,颜色越深Fe的含量越高,Fe在糖玉中以独立铁质矿物的赋存形式分布于透闪石的颗粒间、 微裂隙中。铁质矿物由于其含量低、 粒度细小,本文设计实验对其进行富集后进行测试。将铁质矿物富集后的样品进行透射电镜测试,铁质矿物呈云状集合体,电子花样衍射图显示其矿物为针铁矿。因此,针铁矿分布于透闪石颗粒间、 微裂隙中致使糖玉呈现黄褐色。拉曼光谱显示糖玉表面少见红褐色矿物颗粒为金红石,由于金红石含量少,仅对颜色成因有部分贡献。     

Analytical Solutions of a Model for Brownian Motion in the Double Well Potential

In this paper, the analytical solutions of Schr¨odinger equation for Brownian motion in a double well potential are acquired by the homotopy analysis method and the Adomian decomposition method. Double well potential for Brownian motion is always used to obtain the solutions of Fokker–Planck equation known as the Klein–Kramers equation, which is suitable for separation and additive Hamiltonians. In essence, we could study the random motion of Brownian particles by solving Schr¨odinger equation. The analytical results obtained from the two different methods agree with each other well. The double well potential is affected by two parameters, which are analyzed and discussed in details with the aid of graphical illustrations. According to the final results, the shapes of the double well potential have significant influence on the probability density function.     

分形理论在分子动力学模拟中的应用

本文基于分形理论提出了一个假说,认为实际流体分子的无规运动可以用分数布朗函数作为概率密度函数来描写,而其分数维数可根据分子运动的图像确定。本文以流体Ar作为对象进行了分子动力学模拟,根据分子动力学模拟的结果提取了运动的分数维数,构造了描述分子无规运动的分数布朗函数,并对所提出的假说进行了验证。