2-羟丙基三甲基氯化铵壳聚糖的制备及其性能研究

以脱乙酰度为95.37%的壳聚糖(CTS)为原料,异丙醇为溶剂,2,3-环氧丙基三甲基氯化铵为改性剂,于80℃反应12 h合成了水溶性季铵盐2-羟丙基三甲基氯化铵壳聚糖(HACC)。HACC的吸水保水性是CTS的2倍～3倍,加入化妆品中培养2周后菌落总数少于100 CFU.g-1。     

离子色谱线性梯度淋洗分离阴离子的计算机模拟

建立了使用氢氧化钠淋洗液时用计算机模拟离子色谱梯度淋洗分离阴离子的新方法,研究了在线性梯度淋洗过程中不同时间阴离子在色谱柱中的位置及所在位置的淋洗液浓度,得出阴离子在不同时间的容量因子、迁移速度,通过积分得到保留时间。再根据离子色谱峰峰形变化的规律,得到色谱峰峰形的参数。模拟色谱图保留值与实验值的相对误差小于5%,模拟色谱图的色谱峰峰形与实验所得到的色谱图的色谱峰峰形也非常接近。     

Computer simulation of conformational movement based on interconversion phenomena

A computer method has been developed which is an alternative to molecular dynamics in the sense that it pictures conformational motion. It simulates propagation in conformational movement based on conformational interconversion phenomena. The method starts with the knowledge of the topology of the conformational potential energy hyper-surface, which is described by the minima and the transition states. The topology is obtained by the recently described software . The simulation of conformational motion is based on the Boltzmann statistics of movement between the minima and the transition states at a given temperature. The method is illustrated for methyl--glucopyranoside and - -galNAc(1-3)[- -Fuc(1-2)]Gal-O-Me molecules. Conformational transitions of hydroxyl groups as well as glycosidic linkages are discussed.     

聚己内酯聚醚嵌段共聚物和共混物的表面性质对其药物释放行为的影响

聚己内酯聚醚嵌段共聚物和共混物的表面性质对其药物释放行为的影响王卫华，贝建中，王智峰，王身国（中国科学院化学研究所北京１０００８０）关键词聚己内酯聚醚嵌段共聚物，共混物，电子能谱，表面性质，药物释放行为聚己内醋（ＰＣＬ）具有优良的药物通透性和生物相容...     

Voltammetric Behavior of Water‐Soluble Endohedral Metallofullerene Derivatives

Voltammetric behavior of water‐soluble endohedral metallofullerene derivatives Gd@C₈₂(OH)₅(NHCH₂COOH)₉ (GN) and Gd@C₈₂(OH)₆(NHCH₂CH₂SO₃H)₈ (GS) was characterized in 0.1 M KCl solution by CV and DPV. They showed similar redox behavior, that is, a reversible electroreduction process on HMDE was found; in the mean time, an irreversible oxidation process and an irreversible reduction process on GC electrodes were also observed. The results reveal that these two water‐soluble endohedral metallofullerene derivatives have good electron donating ability and poor electron accepting ability due to hydroxy groups, aminoacetic acid and aminoethyl sulfonic acid connected to the C₈₂ cage in comparison with Gd@C₈₂.     

Zur Struktur und Reaktivität des Diammoniumhexafluoromanganats(IV)

About the Structure and Reactivity of Diammonium Hexafluoromanganate(IV) Electrolytic oxidation of an aqueous suspension of MnF₂ containing NH₄F, and subsequent crystallization in 40% HF yields yellow crystals of (NH₄)₂MnF₆. It crystallizes in the hexagonal K₂MnF₆ type structure with the space group P6₃mc and a = 5.903; c = 9.565 Å; Z = 2. With in situ powder diffraction studies it is shown, that (NH₄)₂MnF₆ is gradually reduced in a NH₃ atmosphere between 30 and 230 °C to afford (NH₄)₃MnF₆, (NH₄)₂MnF₅, and finally NH₄MnF₃. (NH₄)₃MnF₆, thereby, forms a hitherto unknown cubic (a = 9.082 Å) high temperature modification with the cryolite type structure. Under N₂ the thermal decomposition of (NH₄)₂MnF₆ proceeds via NH₄MnF₄ to yield MnF₂.     

Quantitative aspects of gradient HPLC of copolymers from styrene and ethyl methacrylate

Summary Prerequisite of quantitative evaluation in chromatography is equivalence of sample composition and detector signal. This includes complete retention and proper elution of all sample constituents. In polymer HPLC, complete retention requires a poor starting eluent, a sufficiently active column, and a low ratio of injection volume to column volume. On small pore columns, insufficient retention caused the polymer to elute either in the interstitial volume (sample exclusion), together with the sample solvent, or immediately after the solvent plug.Stat-copoly(styrene/ethyl methacrylate) samples are more difficultly retained thanstat-copoly(styrene/acrylonitrile) specimes. With the former copolymer it could be shown that incomplete retention did not cause sample demixing. In order to gain complete retention, non-exclusion HPLC of polymers should be performed with columns whose solvent volume is at least 50 times as large as the injection volume. This consequence is of practical importance in chromatographic cross-fractionation where rather large volumes of SEC eluate are injected into the apparatus for gradient HPLC.     

D160大孔吸附树脂对染料木黄酮吸附性能的研究

研究了D160大孔吸附树脂对染料木黄酮的吸附性能.结果表明,在pH4.00时,该树脂对染料木黄酮有较好的吸附性能;静态饱和吸附容量为64.5mg/g树脂;用95%乙醇溶液作解吸剂,二次累计解吸率接近100%;表现速率常数k298=1.01×10-4s-1;测得吸附热力学参数分别为:△H=32.2kJ/mol,△S=119J/(mol·K),△G288=-2.03kJ/mol,△G298=-3.22kJ/mol,△G308=4.41kJ/mol.等温吸附服从Freundlich和Langmuir等温吸附规律;研究还表明,提高振荡频率对吸附有利.     

超高交联吸附树脂吸附对硝基苯乙酮的热力学研究

比较两种超高交联聚苯乙烯吸附树脂NJ-8、AM-1与Amberlite XAD-4(以下简称XAD-4)对对硝基苯乙酮的静态吸附行为，根据吸附等温线研究了吸附热力学性质．在298～318K和研究的浓度范围内，NJ-8，AM-1、XAD-4对对硝基苯乙酮的吸附平衡数据符合Freundlich吸附等温方程．结果表明：吸附为放热过程，适当降低温度有利于吸附．计算了对硝基苯乙酮在NJ-8，AM-1、XAD-4树脂上的吸附焓变、自由能变，吸附熵变．对吸附行为作了合理的解释。