On the Isomorphism of Some Groups with One Defining Relation

Each of the groups in the class under consideration in the paper is presented by one defining relation depending on three integral parameters and is an HNN-extension of some Baumslag—Solitar group. Necessary and sufficient conditions for two groups of this class to be isomorphic and also for two nonisomorphic groups to be homomorphic images of each other are obtained. A consequence of this fact is the negative answer to Question 3.33 in “The Kourovka Notebook.”     

Self-organisation of female menopause in populations with child-care and reproductive risk

In this paper, by using a computer model for the evolution of age-structured populations, we show that in a sexual population subject to: (i) senescence, (ii) age-increasing reproductive risks, and (iii) long juvenile dependence, menopause arises spontaneously, in order to guarantee the survival of the offspring. Received: 12 September 1998 / Accepted: 14 September 1998     

保费到达为更新过程的复合更新风险模型

本在经典风险模型基础上，把索赔到达过程Nt加以推广为更新过程。且在保单到达非均匀的前提下，把保单到送过程推广为更新过程Mt，得到有限时间t孕余的瞬时分布ψ（u,θ0,t,α），然后求得时刻t的生存概率ψ（t,u，θ0)。     

Ring cleavage of dihydropyrimidine skeleton

The first observation of ring cleavage between positions 1 and 2 of a 1,4-dihydropyrimidine skeleton was reported upon the nucleophilic addition of 4,6-unsubstituted 1,4-dihydropyrimidine with 3 equiv of an aniline derivative or phenylhydrazine in the presence of 0.1 equiv of pyridinium p-toluenesulfonate (PPTS) in CH₂Cl₂; the nucleophilic reactions of 4-methyl-6-unsubstituted 1,6(3,4)-dihydropyrimidine with the same amines gave conventional substituted products at position 2. The effect of this ring opening was found to be due to the electron density of the benzene ring of a nucleophilic amine. On the other hand, aralkylamines, alkylamines, or heterocyclic amines did not cleave the skeleton. The ring-opening chemical structure was confirmed by X-ray crystallographic analysis. This characteristically different phenomenon may be due to the pattern of two CC double bonds of 1,4-DP and 1,6(3,4)-DP as well as to the effect of two substituted groups on the DP ring.     

生灭型半马氏骨架过程

本文首先引进了生灭型半马氏骨架过程的定义,求出了两骨架时跳跃点τn-1(ω)与τn(ω)之间的嵌入过程X(n)(t,ω)的初始分布及寿命分布.得到了生灭型半马氏骨架过程的一维分布.其次引进了生灭型半马氏骨架过程的数字特征并讨论了它们的概率意义及相互关系.讨论了生灭型半马氏骨架过程的向上和向下的积分型随机泛函.最后讨论了它的遍历性及平稳分布,求出了平均首达时间及平均返回时间.得到了常返和正常返的充分必要条件,求出了在正常返的条件下的平稳分布.     

Mannose-Modified Multi-Walled Carbon Nanotubes as a Delivery Nanovector Optimizing the Antigen Presentation of Dendritic Cells

Dendritic cells (DCs) based cancer immunotherapy is largely dependent on adequate antigen delivery and efficient induction of DCs maturation to produce sufficient antigen presentation and ultimately lead to substantial activation of tumor-specific CD8⁺ T cells. Carbon nanotubes (CNTs) have attracted great attention in biomedicine because of their unique physicochemical properties. In order to effectively deliver tumor antigens to DCs and trigger a strong anti-tumor immune response, herein, a specific DCs target delivery system was assembled by using multi-walled carbon nanotubes modified with mannose which can specifically bind to the mannose receptor on DCs membrane. Ovalbumin (OVA) as a model antigen, could be adsorbed on the surface of mannose modified multi-walled carbon nanotubes (Man-MWCNTs) with a large drug loading content. This nanotube-antigen complex showed low cytotoxicity to DCs and was efficiently engulfed by DCs to induce DCs maturation and cytokine release in vitro, indicating that it could be a potent antigen-adjuvant nanovector of efficient antigen delivery for therapeutic purpose.     

Development of the radical C–O coupling reaction of phenols toward the synthesis of natural products comprising a diaryl ether skeleton

Compounds comprising a diaryl ether skeleton exist among natural phenols. The diaryl ether skeleton is thought to be biosynthesized through the coupling of two or more phenols. It is an important structural feature in medicines and agrochemicals, and it is imperative to develop methods for constructing such skeletons in organic synthesis. However, by the synthesis method through the coupling of phenols, coupling occurs preferentially at the ortho-substituted carbon atom of phenols. In this study, various radical-generating reagents and conditions were investigated with the aim of developing a short-step construction method of the diaryl ether skeleton by the radical homo-coupling of two phenol molecules. In addition, cross-coupling reactions between radicals of 2,4,6-tri-tert-butylphenol and p-substituted phenol were conducted to synthesize eight C (ortho)–O coupling products. Based on the results, a computational chemical approach was employed to verify the cause of C (ortho)–O bond formation.     

N-Hydroxyhomoazaadamantanone and its complexes with dioxo-molybdenum(VI) and copper(II): synthesis and structure

A hydroxamic acid of a new type, N-hydroxyhomoazaadamantanone (HL), has been synthesized, combining several structure peculiarities: cage skeleton, heterocyclicity, and rigidly fixed cis-orientation of the oxygens of the hydroxamate fragment of the molecule. Complexes of HL with dioxo-molybdenum(VI) ((MoO₂LC₂H₅OH)₂O) and copper(II) (CuL₂) have been synthesized. All compounds were characterized by IR and ¹H NMR spectroscopy. X-ray structural analyses of N-hydroxyhomoazaadamantanone hydrochloride and the coordination compounds have been carried out.     

四元数矩阵实表示的基本性质及应用

在四元数实矩阵表示的基础上,给出了四元数矩阵的相同表示,利用友向量的概念,给出了这种实表示的性质,并进一步研究了四元数力学中的系列数值计算问题.