Calycilactone A, a novel hexacyclic alkaloid from Daphniphyllum calycillum

A novel Daphniphyllum alkaloid with a rearranged fused-hexacyclic ring system, calycilactone A, was isolated from the leaves of Daphniphyllum calycillum (Daphniphyllaceae), and the structure and relative stereochemistry of the new compound were elucidated on the basis of spectroscopic data.     

层柱催化剂［Zn_2Al（OH）_2］［SiW_（11）O_（39）Co（H_2

层柱催化剂［Ｚｎ_２Ａｌ（ＯＨ）_２］［ＳｉＷ_（１１）Ｏ_（３９）Ｃｏ（Ｈ_２Ｏ）］_（０．８３）４Ｈ_２Ｏ的合成新途径及其对苯甲醛Ｈ_２Ｏ_２氧化的催化活性胡长文，贺庆林，张云峰，张继余，王恩波（东北师范大学化学系，长春１３００２４）关键词层柱催化剂，苯?..     

氯化聚乙烯对甲基丙烯酸甲酯／苯乙烯共聚动力学的影响

将甲基丙烯酸甲酯（ＭＭＡ）／苯乙烯（Ｓ）在氯化聚乙烯（ＣＰＥ）存在下进行悬浮溶胀接枝共聚，考察了ＣＰＥ对ＭＭＡ／Ｓ共聚动力学行为的影响．ＣＰＥ提高了聚合体系的粘度，使自动加速提前，扩散因素增加，对共聚有阻滞作用．ＣＰＥ是链转移剂，使ＭＭＡ／Ｓ共聚物分子量降低．ＣＰＥ对ＭＭＡ的吸附渗透优于对Ｓ的吸附，造成接技部分与非接技部分组成的差异．ＣＰＥ含量、溶胀时间、转化率、硫酸用量对共聚组成均有影响。     

强酸阳离子交换树脂催化性能的研究

通过叔丁醇脱水生成异丁烯的反应研究对比了国内外常见种类的凝胶型和大孔型强酸阳离子交换树脂的催化性能，并对树脂的性质，预处理方法，以及其用量和再生程度等因素对树脂催化活性的影响进行了研究。在此基础上，合成了具有较高催化活性的新型大孔强酸阳离子交换树脂。     

聚氯乙烯—丁腈橡胶—氯丁橡胶三元共混物的研究

测定了聚氯乙烯（ＰＶＣ）－丁脯橡胶（ＮＢＲ－２９）－氯丁橡胶（ＣＲ）三元共混物的冲击性能和应力－应变行为，用动态力分析、扫描电和透射电镜研究了共混物的相容性和形态结构。结果表明，ＮＢＲ－２９对ＰＶＣ，ＣＲ有良好的增容作用，三元共混物是部分相容的二相体系，具有良好的抗冲击性能。     

（PdCl2—PVP）／Al2O3催化剂中Pd状态的探讨

氯化钯先锚定在聚乙烯吡咯烷酮上后进一步负载到Al_2O_3上所制的催化剂[简称(PdCl_2-PVP)/Al_2O_3]是一种活性、选择性高,稳定性好的烯烃、二烯烃和多烯烃加氢催化剂。本文结合加氢反应,使用XPS、FT-IR、电镜及用CO为探针的FT-IR,对这种催化剂进行了考察。实验说明,在这种催化剂中,钯的价态是在0—2之间。红外光谱在486cm~(-1)处有一微弱的小峰,说明存在Pd—N的配位键。催化剂中钯含量低时(0.2wt％)稳定性好,不吸附CO,活性中心是络合钯原子;当钯含量较高时(0.7wt％),催化剂的初活性虽不低,稳定性却较差,这种催化剂能吸附CO,IR谱图上仅在1919cm~(-1)处有CO桥式吸附态的伸缩振动。表明除络合钯原子外,还有聚集的钯金属存在。FT-IR尚表明,PVP在Al_2O_3上可能并非单纯的物理吸附。电镜结果表明,PVP在Al_2O_3上呈30—70(?)的微球状,(PdCl_2-PVP)/Al)_2O_3上的(PdCl_2-PVP)亦呈微球状,与前者无明显区别,这种催化剂中其活性中心是络合钯原子。     

Swelling kinetics and release characteristic of crosslinked chitosan: Polyether polymer network (semi-IPN) hydrogels

The aqueous swelling kinetics of a series of crosslinked chitosan (cr-CS) with glutaraldehyde (GA) interpenetrating polyether hydrogels have been studied as functions of pH, the N-deacetylation degree of chitosan, the amount of crosslinking agent, the electrolyte composition in solution, temperature, and gel composition. Based on these results, the swelling mechanism of the hydrogels was discussed. The release profiles of chlorhexidini acetas from the semi-IPN were also investigated. © 1994 John Wiley & Sons, Inc.     

Novel alginate-poly(L-histidine) microcapsules as drug carriers: in vitro protein release and short term stability

Spherical, smooth-surfaced and mechanically stable alginate-poly(L-histidine) (PLHis) microcapsules with narrow particle size distributions were prepared by incubating calcium alginate beads in aqueous solutions of PLHis. The in vitro release characteristics, drug loading and encapsulation efficiency of the microcapsules were investigated using bovine erythrocytes hemoglobin (Hb) as a model drug. The results showed that the concentration of Ca(2+) ions had a considerable effect on the drug loading, encapsulation efficiency and in vitro release behavior of the microcapsules. When the concentration of CaCl(2) in the PLHis solution was increased from 0 to 3.0% (w/v), the drug loading and encapsulation efficiency decreased significantly from 38.0 to 4.3% and from 92.9 to 8.0%, respectively, while the total cumulative release of Hb from microcapsules in phosphate buffered saline solution (PBS, pH 6.8) decreased from 96.2 to 72.8% in 24 h. No significant protein release was observed during 70 h of incubation in hydrochloric acid solution (pH 1.2). However, under neutral conditions (PBS, pH 6.8), the Hb was completely and stably released within 24-70 h. An explosion test showed that the stability of alginate-PLHis microcapsules depended strongly on the concentration of PLHis and the calcium ions in solution. [Diagram: see text] Microscopy photo of Hb-loaded alginate-PLHis microcapsules.     

HMS和NaY固载酒石酸钛配合物的研究

利用化学键合和“瓶中造船”方法,成功地将酒石酸钛配合物接枝到HMS(heragonal mesoporous silicas)上或包络合于微孔NaY内.FT-IR表征表明酒石酸钛在HMS上是通过与载体表面羟基发生交换作用而被固载的;在NaY载体上则是通过包络合被封装在载体的超笼内.UV-Vis可见漫反射表征表明两类固载型催化剂有着相似的钛配位环境.在催化肉桂醇环氧化反应中,HMS键合型催化剂的反应转化率比NaY包络型催化剂的高;但后者在环氧化选择性上要高于前者.回收样品的重复使用实验结果表明,两类固载型催化剂在重复使用过程中均存在不同程度的失活.     

Morphological and Structural Studies of sPS/aPS Blends

Inrecentyears,thenewsedricrystallinepolymersyndiotacticp0lystyrene(sPS)hasat-ITactedmuchattentionduetoitsg0odchendcalresistanceandenhancedmechanicalperformanceatelevatedtemPeratUre.'H0wever,itexhibitshighbrittlenessandpoorimPact-resistanceandtCar-resistance.2Therefore,itisnecessarytomodifyitwithtougheningpolyIners.AsimPlemeth0dto0verc0methedriscibilityofatwo-phaseblendofsPSandatougheningpolymristotwrovetheinterfacialaffmity,wheretheadditionofablockcoP0lymerisconsideredtobemosteffective.3…