三磷酸胞苷在Duolite A-30树脂上的交换过程研究

根据CTP在离子交换树脂上的吸附容量和分离因数的大小,确定Duolite A-30树脂适合CTP与CDP,CMP之间的分离.对CTP在Duolite A-30树脂上的吸附动力学和热力学研究表明,在283.15K~303.15K之间,CTP的质量浓度在7.5g/L以上时,Duolite A-30树脂对CTP的吸附主要受颗粒扩散的控制,其有效扩散系数为D=3.47×10-7cm2/s,溶液的质量浓度≤1.0g/L时,CTP与Duolite A-30树脂之间的交换速率主要受液膜控制,其液膜扩散系数为Kf =4.112×10-4/s.同时测定了不同条件下三磷酸胞苷溶液在Duolite A-30树脂固定床离子交换柱中的穿透曲线,研究了进口浓度、进口流速、原料液温度、原料液的pH值及柱高对穿透曲线的影响.用二阶动力学推动力模型描述固定床动态过程,考察了轴向返混对穿透曲线的影响,并从穿透曲线回归得到总传质系数,模型计算值与实验数据符合良好.     

同时测定核苷酸口服液中二磷酸核苷的毛细管区带电泳法

建立了一种毛细管区带电泳法，用于同时测定5种核苷酸－鸟苷二磷酸（GDP）、尿苷二磷酸（UDP）、腺苷二磷酸（ADP）、胞苷二磷酸（CDP）、次黄嘌呤核苷酸（IDP）；研究了缓冲液的pH值及磷酸盐的浓度对分离5种核苷酸的影响，5种核苷酸在75mmol/L三羟甲基氨基甲烷（Tris)－50mmol/L磷酸二氢钠（NaH2PO4）、pH为8．00的缓冲液可以基线分离；另外还研究了中入阳离子表面活性剂十六烷基三甲基溴化胺（CTAB）以及CTAB的浓度和进样时间对分离5种核苷酸的影响；该法成功地应用于测定核苷酸口服液中ADP、CDP、GDP、UDP的含量。     

高效液相色谱手性固定相分离β-胸苷中的α-胸苷异构体

齐多夫定是最早经美国食品药品监督管理局（FDA）批准上市的抗艾滋病药物。β-胸苷是齐多夫定的主要原料。作为一种存在立体异构体的化合物,伊胸苷中α-胸苷的含量直接关系到其后续合成药物的质量及药效。本文采用CHIDEX—SKP环糊精类手性固定相,建立了分离检测β-胸苷中α-胸苷异构体（结构见图1）的高效液相色谱方法,同时还研究了流动相组成和流速等因素对这对异构体分离的影响。     

Detection and Sequence Identification of Dinucleotides Produced from N‐Phosphoryl Alanine and Four Nucleosides by HPLC‐ESI‐MS/MS

本文利用液相色谱质谱联用技术研究了N－磷酰化丙氨酸和四种核苷（腺苷,尿苷,胞苷和鸟苷）的模板反应产物。结果表明生成了不同类型的单核苷酸和二核苷酸,并且生成的二核苷酸序列也得到了确证。研究结果揭示,二核苷酸骨架裂解形成的c离子可以作为确证二核苷酸序列的诊断离子。本文首次证明不论是在正离子模式还是在负离子模式下,c离子都可以用来确定此反应体系中生成的二核苷酸产物的序列。     

十二烷基糖苷的反相高效液相色谱分析

烷基多苷（APG）是一类环保型非离子表面活性剂,由脂肪醇与糖制备,为单糖苷和多糖苷的混合物.受分离方法的限制,难以得到其中各组分的纯品,因此APG的组成测定一直未得到很好的解决.本文采用制备色谱对其进行分离,经核磁共振氢谱（^1H NMR）确定各组分的结构,用高效液相色谱（HPLC）分析测定了相对质量校正因子（f）,为完善APG的结构分析及质量控制奠定了基础.     

微波-超声波辅助合成聚乙烯亚胺包覆Mn掺杂ZnS量子点用于室温磷光检测三磷酸鸟苷

利用微波-超声波辅助方法合成了水溶性聚乙烯亚胺包覆Mn掺杂ZnS量子点,并建立了基于该量子点的室温磷光检测三磷酸鸟苷(GTP)的新方法。该量子点对GTP具有较高的灵敏度和选择性,能区分GTP与其结构类似物三磷酸腺苷(ATP)、三磷酸胞苷(CTP)、三磷酸尿苷(UTP)、二磷酸腺苷(ADP)和一磷酸腺苷(AMP)。该量子点的室温磷光对GTP的响应在3 min内达到平衡,其磷光增强值与GTP浓度呈良好的线性关系,对GTP的检出限为0.6μmol/L。该方法成功应用于癌细胞提取液中GTP的检测,为GTP的检测提供了新方法。     

NAD-硅胶亲和色谱固定相的合成和在核苷酸及其碱基分析中的应用

ＮＡＤ－硅胶亲和色谱固定相的合成和在核苷酸及其碱基分析中的应用于世林,苗凤琴,杨朝霞,冯茹（北京化工大学应用化学系,北京,１０００２９）关键词烟酰胺腺嘌呤二核苷酸（ＮＡＤ）,亲和色谱,核苷酸烟酰胺腺嘌呤二核苷酸（ＮＡＤ,辅酶Ⅰ）是多种脱氢酶的辅酶,通...     

5-氮胞苷诱导骨髓间充质干细胞向心肌细胞分化的研究

分离大鼠骨髓间充质干细胞,体外培养呈现成纤维细胞表型,用12μmol//L 5-氮胞苷(5-aza)诱导培养,一周后细胞变为细长形成杆状.两周后培养细胞与临近的细胞融合,三周后形成类肌管状结构.通过RT-PCR检测,5-氮胞苷诱导前,间充质干细胞表达α-actin,desmin和MEF-2D,5-aza诱导后表达β-MHC和GATA4.westem Blot分析结果表明α-actin在诱导前后都表达,而myosin则在诱导后才表达.免疫荧光标记α-actin和β-MHC,证实了上述结果,即在5-氮胞苷诱导前后细胞表达α-actin,诱导后myosin才在细胞质中表达,Myosin和β-MHC是心肌细胞特异表达的蛋白.上述结果表明骨髓间充质干细胞具有向新生心室肌分化的潜能,这些诱导分化的细胞为心肌梗塞移植治疗提供一种潜在的供体细胞.     

高效液相色谱/二极管阵列检测/质谱/质谱(HPLC/DAD/MS2)联用在板蓝根注射液成分鉴定中的应用

用HPLC/DAD/MS2联用仪,鉴定了板蓝根注射液中含有的核苷类物质。色谱条件:Luna C18 色谱柱(250 mm×4.6 mm i.d., 5 μm);甲醇-水梯度洗脱,流量0.8 mL/min; 柱温25 ℃。用二极管阵列检测器记录各个色谱峰的紫外吸收光谱,色谱检测波长254 nm。质谱条件:电喷雾离子源(ESI);正离子检测;扫描范围m/z 50-800。记录质量色谱图和各个色谱峰的一级、二级质谱图,并对质谱结果进行解析,通过与对照品比较,确定板蓝根注射液样品中含有腺苷、鸟苷、尿苷、胞苷及腺     

用层析法分离磷酸酯基化学修饰的二核苷酸的非对映异构体

本文报道用高效液相色谱法和高效薄层色谱法分离磷酸醌基化学修饰的二核苷酸二尿苷硼烷磷酸酯，二胸苷硫代磷酸酯，二（２＇－脱氧－２＇－氟）尿苷及胞苷硫代磷酸酯的非对映异构体，所得到的非对映异构体的ＲＦ值和＾３１Ｐ－ＮＭＲ化学移植之间的关系符合一般规律，即移动快的异构体有较高的位移植，移动慢的异构体有较的化学位移植。     

Liquid Metals and Liquid Semiconductors

Numerous liquid systems have electrical properties which resemble those of crystalline and amorphous semiconductors. The existence of “semiconducting” behavior in these liquids is mostly related to a continuous transition from a metallic to a “semiconducting” state when a thermodynamic variable such as temperature, density or concentration is changed. Changes in the nature of the chemical interaction and the associated changes in the structure of the liquid are of fundamental importance for the transition to a “semiconducting” state. This will be demonstrated for the ionic liquid CsAu, for covalent liquid selenium, and for expanded liquid metals.     

液/液两相催化新进展--温控非水液/液两相催化

温控非水液/液两相催化,是指一类由两种或多种液态有机物组成的催化反应体系,其特点是体系的相态变化可通过温度来调控,即体系在高温时相互混溶呈均相,低温不溶分成两相,催化剂和产物分别处于两相,从而为解决均相催化剂分离难的问题开拓了一个新方向,是液/液两相催化研究领域最引人注目的进展之一.首次以"温控"为主线将氟两相催化作为温控液/液两相催化的一个特定类型纳入"温控非水液/液两相催化"范畴,并与其它通过温度来调控的有机液/液两相和作者提出的温控相分离催化串在一起作一较为详细的评述.     

温控液/液两相催化进展*

本文以作者在温控水/有机两相及温控非水液/液两相催化领域的研究工作为主线,对这一领域的研究进展作一评述,重点是环绕经典水/有机两相催化体系存在“应用范围受底物水溶性限制”的根本问题展开。特别是对“温控相转移催化”作了较为详细的介绍,同时,按体系介质不同,对氟两相体系、PEG两相体系、离子液体两相体系等非水液/液两相体系以及温控相分离催化分别作了阐述。     

LC Determination of Mono-Substituted Phenols in Water Using Liquid–Liquid–Liquid Phase Microextraction

A simple liquid–liquid–liquid microextraction device of new design was used to pre-concentrate phenols from water samples before liquid chromatographic (LC) analysis. Extraction was induced by the pH difference inside and outside an organic phase located at the interface. The pH of the donor phase outside the organic phase was adjusted to 1 with HCl whereas the acceptor phase was a basic solution at pH 13. On stirring neutral phenols were extracted into the organic solvent then back-extracted into 1 μL of basic acceptor solution suspended from the tip of a micro syringe. The acceptor phase was then withdrawn into the micro syringe and injected directly into the LC. The technique uses a low-cost disposable extraction ‘device’ and is very convenient to operate. Up to 230-fold enrichment of analytes could be achieved. This procedure could also serve as a sample clean-up step because neutral and basic compounds were not extracted into the acceptor phase. The RSD (n = 5) was better than 6.2% and the linear calibration range was from 1 to 1000 µg–L⁻¹ with r ² ≥ 0.992.Optimization of experimental conditions (rate of stirring, ionic strength of the sample solution, concentration of reagents, time of extraction, and organic solvent volume) were also examined. The method was applied to the determination of phenols in tap and well waters.Revised: 14 February and 29 March 2005     

聚合物分散液晶从液体桥的组装

We report the organization of polymer-dispersed liquid crystals (PDLCs) into ordered concentric rings over large areas by drying a drop of bound PDLC toluene solution (i.e., confined between a spherical lens and an indium tin oxide (ITO)-coated glass substrate; sphere-on-ITOgeometry). The formation of regular ring-like deposits was a direct consequence of controlled "stick-slip" cycles of three-phase contact line during the course of solvent evaporation, which was effectively regulated through the use of the sphere-on-ITO geometry. This simple approach based on controlled evaporative organization may provide a new means of processing polymer/LC mixture to produce ordered surface patterns in one step, where microscopic LCs are dispersed within the polymer matrix.     

液晶离聚物--液晶行为的研究

综述了液晶离聚物中离子的种类,位置、在链中浓度对液晶性能的影响,无论是主链还是侧链液晶离聚物,离子的种类,位置对中介区间的宽度有影响,但对中介相类型基本没有影响,当离子浓度增大到一定值时,液晶性能消失。     

Synthesis of Free-Standing Crystalline Barium Titanate Films at Vapor/Liquid or Liquid/Liquid Interface

Synthesis of free-standing crystalline barium titanate (BaTiO₃) films at vapor/liquid or liquid/liquid interface at room temperature has been investigated. High concentration Ba, Ti alkoxides precursor solution (1.2 mol/l) or pre-hydrolyzed precursor solutions by water vapor in a H₂O/Ba molar ratio of 0 to 6 were used as dropping solutions at the interfaces. Transparent gel films were formed when partially hydrolyzed precursors (H₂O/Ba = 2 to 3) were spread out on a N₂/liquid paraffin interface. The films shrank from syneresis and vaporization of the solvent during aging at room temperature. As a result, free-standing transparent films with a thickness of around 1 m and little stoichiometric deviation were obtained by separation from the liquid surface and rinse by hexane. The films consisted of crystalline BaTiO₃ particles of less than a few nanometers. Nanostructured dense BaTiO₃ free-standing films with a grain size less than 100 nm were obtained at 1030°C.     

Spontaneous Liquid/Liquid Displacement in a Capillary

When a two-phase column consisting of paraffin oil and silicon oil is placed in an otherwise air-filled, horizontal glass capillary, the column starts moving spontaneously. Silicon oil displaces paraffin oil, which in its turn displaces air at atmospheric conditions; a stable film of silicon oil is left at the receding silicon oil/air meniscus. The driving force for the motion is the difference in capillary pressure at the free interfaces. However, the column moves considerably more slowly than predicted by the driving forces; it appears that the forces resisting the motion at the moving liquid/liquid/solid line are much larger than one would expect on the basis of the interfacial tension and the viscosities of the two phase system. Some considerations are made on the relationship of the theory of Fowkes to our system. Also, a method for measuring low interfacial tensions between immiscible liquids is proposed.