穿心莲内酯衍生物的合成研究进展

穿心莲内酯是中药穿心莲的主要二萜类活性成分之一. 近年来药物及有机化学工作者发现穿心莲内酯及其衍生物具有抗肿瘤, 抗HIV, α-葡萄糖苷酶抑制等活性, 由于其广泛的药理活性而倍受人们的关注. 作者对穿心莲内酯衍生物的合成进行了综述.     

Molecular recognition triggered aptazyme cascade for ultrasensitive detection of exosomes in clinical serum samples

Exosomes have attracted widespread interest due to their inherent advantages in tumor diagnosis and treatment monitoring. However, it is still a big challenge for highly sensitive and specific detection of exosome in real complexed samples. Herein, a molecular recognition triggered aptazyme cascade strategy was developed for ultrasensitive detection of cancer exosomes in clinical serum samples. In this design, one target exosome could capture a large quantity of aptazymes for the first-step signal amplification. And then the captured aptazyme was activated and recycled to release the fluorophore-labelled substrate strand for a cascaded signal amplification. Notably, the activation of aptazyme only occurs when it has bound with target exosome, ensuring a low background. The experimental results show that the limit of detection (LOD) and the limit of quantification (LOQ) are 3.5 × 10³ particles/μL and 1.7 × 10⁴ particles/μL, respectively, which is comparable to the results of most existed fluorescence-based exosome probes. Moreover, this assay possesses high specificity to distinguish exosomes derived from other cell lines. Furthermore, this fluorescence probe was utilized in cancer patient and healthy serum samples successfully, suggesting its great potential for clinical diagnosis and biological studies.     

抗肿瘤药物卡培他滨的合成新方法

研究了抗肿瘤药物卡培他滨的合成新方法. 该方法以廉价的D-木糖为原料制得重要中间体1,2,3-三-O-乙酰基-5-脱氧-D-呋喃核糖(5), 化合物5再与5-F胞嘧啶进行Vorbrueggen反应, 然后经酰胺化, 脱除乙酰基得到卡培他滨, 合成总收率为29.8%. 该方法的关键步骤是化合物3的3-OH构型翻转和5-对甲苯磺酰氧基基团(5-OTs)的还原脱除。结果表明, 该方法原料廉价易得、 反应条件温和、 操作简单、 收率良好且产物易于分离纯化, 适合大规模制备.     

Net-Baryon and Net-Kaon Rapidity Distributions in Ultrarelativistic Heavy-Ion Collisions

In this paper, the gluon distribution is extracted from the KLR-AdS/CFT saturation model and used to investigate net-baryon and net-kaon rapidity distributions in ultrarelativistic heavy-ion collisions. With the same parameters of the saturation model fitting to HERA data and an χ² analysis of the overall constant C, the theoretical results are in good agreement with RHIC data in Au+Au collisions at √s=0.2 TeV. Then, we present the predictive results for net-baryon rapidity distributions in central Pb+Pb collisions at LHC energies of √s=2.76, 3.94, and 5.52 TeV, and give the corresponding values of d N/d y for net-baryon at y=0.     

聚噻吩制备条件对其结构和导电性能的影响

通过改变聚噻吩合成条件(温度、浓度、反应时间)得到各种不同样品, 用FESEM, FTIR光谱, Raman光谱, XRD, UV-Vis光谱和TG等手段对样品进行研究. 结果表明, 不同的制备条件会影响噻吩环的连接方式, 直接影响聚噻吩结构的分布. 导电性能研究表明, 聚噻吩的结构差异和其导电性能直接相关, 实验证明以α-α相连接的聚噻吩有更高的电导率.     

聚噻吩/多壁碳纳米管复合材料结构与导电机理的研究

从结构和相互作用方面对聚噻吩(PTh)/多壁碳纳米管(MWNTs)复合材料进行了研究, 结果表明: 一方面聚噻吩本身的结构对其导电性能有一定的影响, 另一方面MWNTs作为一种掺杂剂, 和聚噻吩之间存在强的相互作用, 电子从MWNTs转移到聚噻吩. MWNTs和它周围被掺杂的聚噻吩通过π-π共轭作用形成相对独立的导电单元, 在复合材料的导电体系中起到主要作用, 随着这种导电单元数量的增加直至相互接触, 形成大的导电体系, 复合材料的电导率达到最大值.     

Contribution of Quark Structure Term in Nucleon Electric and Magnetic Form Factors

The constituent quarks in the nucleon have always been considered as a point-like particle in the relativisticconstituent quark model. However its calculation results of GE^n agree poorly with the new experimental data. Theelectromagnetic structure of light front constituent quarks is considered in this paper. We find that the calculationresults have good agreement with the new experimental data of GE^n after considering the contribution of the quarkstructure term. This treatment seems to be able to improve the fit to experimental data of GEp/GMp,√Q2F2p/kpF1p,and GEn/GMn as well.     

色八重态对高能π–p碰撞过程的贡献

利用QQ色八重态产生机制,计算并讨论了色八重态对高能π–p碰撞过程的贡献.发现,在大PT时,色八重态的贡献不可忽略,甚至超过色单态的贡献.计算结果与未来实验比较,可以检验色八重态产生机制及π介子中的胶子分布函数.     

Multiplicity of Positive Solutions for Critical Fractional Equation Involving Concave–Convex Nonlinearities and Sign-Changing Weight Functions

Mediterranean Journal of Mathematics - This paper is devoted to study a class of fractional equations with critical exponent, concave nonlinearity and sign-changing weight functions. By means of...     

Synthesis and Crystal Structure of Isosteviol Derivatives

Isosteviol (ent-16-ketobeyeran-19-oic acid, I) is a tetracyclic diterpenoid with a beyerane skeleton obtained by acid hydrolysis of stevioside.1 Several tetracyclic diterpenoids, specially the kaurenes, have important biological activities. Recent studies on the microbial transformation of isosteviol have revealed that it is metabolized by Cunninghamella bainieri, Actinoplanes sp., Mucor recurvatus, and Cunninghamella blackesleeana to yield five new metabolites.2 The hydroxylation pattern of these bioactive compounds may influence their binding on to the receptors, as was proposed for the Rabdosia diterpenoids. Therefore, the introduction of hydroxyl groups or unsaturated bonds in saturated and non-hydroxylated diterpenoids, like isosteviol, may enhance existing properties or lead to new biological activities. Although some beyeranes have been subjected to biotransformations by fungi,4 there are few report in the literature related the chemical transformation of Isosteviol. In the present study, we try to develop the chemical transformation of isosteviol and other beyeranes in order to obtaining some bioactive compounds with beyerane skeleton. Seven isosteviol derivatives, Ⅱ-Ⅷ, were therefore synthesized and characterized. The X-ray crystal strcture of H(R = H) was also determined.