The Syntheses and Properties of Poly(L-Lactide)

Poly (L-lactide) was prepared by bulk polymerization of L-lactide at 140℃ in the presence of stannous octoate. The polymer products were characterized by number average molecular weight Mn, weight average molecular weight Mw and molecular weight distribution MWD (Mw/Mn) respectively. The results showed that stannous octoate was a high effective catalyst, and coordinated insertion mechanism of the reaction was proposed.     

生物降解材料聚乳酸的合成与表征

以乳酸(LA)为原料,采用直接熔融法和固相缩聚法,通过优选催化剂、分步除水、连续通氮气和高真空缩合等工艺,直接缩聚合成可用于改性的聚乳酸(PLA).研究了直接熔融法和固相缩聚法的聚合时间、体系真空度、聚合工艺等对聚乳酸分子量的影响.通过用酸值变化来监测反应的进程,用粘度法测定了产物的粘均分子量,并以红外光谱对产物进行了表征.结果表明,熔融法的最佳工艺为:辛酸亚锡为催化剂(0.5 wt%),聚合温度175℃,聚合时间12 h,体系真空度30 Pa;固相缩聚法的最佳工艺:辛酸亚锡为催化剂(0.5 wt%)、体系真空度60 Pa、聚合温度150℃、聚合时间10 h.     

聚乳酸及其共聚物的制备和降解性能

以D,L-丙交酯和聚乙二醇为原料,在催化剂辛酸亚锡作用下常压氮气保护制备了聚乳酸及其聚乙二醇改性聚乳酸.考察了聚合温度、辛酸亚锡用量对聚乳酸相对分子质量的影响及聚合物在不同降解介质中和不同相对分子质量聚合物的降解规律,并用IR,¹H-NMR,GPC对聚乳酸及其共聚物进行了表征.结果表明,当单体和辛酸亚锡的摩尔比为5 000、聚合温度在160 ℃时,常压聚合5 h即可得到适合作药物控释载体且黏均相对分子质量为6.3×10⁴的聚乳酸;聚乳酸在去离子水、0.01 mol/L盐酸溶液、pH=7.4磷酸盐缓冲液、0.01 mol/L氢氧化钠溶液4种降解介质中,在碱液中的降解速率最快;相对分子质量较小的聚乳酸降解较快,且聚乙二醇改性的聚乳酸比聚乳酸降解快.     

Effect of molecular weight and structure on antitumor activity of oxidized chitosan

Various low molecular weight chitosans were prepared by oxidative degradation with H₂O₂, and characterized by IR,¹³C-NMR and gel permeation chromatography. Their carboxylic contents increased with decrease in molecular weight (M _w ). The antitumor test of the samples against sarcoma 180 tumors suggested that the water-soluble chitosan with higherM _w have higher inhibitory ratioin vivo. The introduction of carboxylic group is advantage to water-solubility of chitosan, but more acidic groups might decrease the function of amino groups of chitosan against sarcoma 180 tumor. Foundation item: Supported by the National Natural Science Foundation of China (No. 29977014) Biography: Qin Cai-qin (1965-), male, Ph. D candidate, Associate professor, research direction: biopolymers.     

聚L-丙交酯的制备及其热稳定性能的研究

对聚丙交酯的合成和热稳定性进行了研究。单体重结晶次数、辛酸亚锡浓度、聚合时间等条件均是影响聚合物特性粘数的重要因素。热稳定剂对聚丙交酯的分子量几乎没有影响。优化聚合条件可以获得粘均分子量大于200000的聚丙交酯材料,聚合结果具有良好的重复性。实验表明在高于聚合物熔点温度以上,聚丙交酯表现出热不稳定性。热稳定剂ULTRONOX 626A能够有效降低聚丙交酯的热降解幅度。     

Effect of KBr on the micellar properties of CTAB

The effect of KBr on the size, shape and microviscosity of CTAB micelles has been investigated by means of laser light scattering (LLS),¹H NMR measurements and fluorescence probe. The data obtained from the various techniques are quantitatively in agreement. The R_h of micelles in 0.01 rnol · L⁻¹ CTAB solution increases from 3.5 nm to 43 nm andR _g increases to 89 nm with addition of KBr salt. In this process, both the microviscosity and molecular weight of micelles M_w have noticeable increases, too. The rod-like micelles are formed at 0.1 rnol · L¹ KBr and the worm-like micelles are formed at above 0.2 rnol · L^-1 KBr.     

Comparison of photovoltaic devices based on MEH-PPV with various molecular weights

Theneedforefficient,inexpensiveandrenewableenergysourcesisstimulatingnewapproachestothepro-ductionoflow-costphotovoltaicdevices.Althoughinor-ganicsemiconductorsaretheprimaryproductions,highfabricationcostsmakeinorganicsolarcelldifficulttomeetlarge-scaleapplicationsduetoitscomplicatedtech-nology,highcostandrigormaterialprocessing.Thesolarcellsbasedonorganicmolecule[1]andconjugatedpoly-mer[2—6]havealreadywelldeveloped.Conjugatedpolymerphotovoltaicdeviceshaveattractedagreatdealofatten-tionduetot…     

斑点鳟的外形特征与消化系统结构

【目的】研究斑点鳟Oncorhynchus mykiss外部形态特征与内部消化系统结构。【方法】观察并描述斑点鳟外部形态特征,测量30尾斑点鳟的外部形态参数,对其进行相关性分析;解剖观察斑点鳟的消化系统结构特征。【结果】斑点鳟外部形态参数全长(LT)与体长(LB)的相关关系为LT=1.21 LB-3.25(R2=0.948),体质量(W)与全长(LT)的关系为W=0.001 LT3.562(R2=0.754),其余几项形态参数之间相关性较低;可数性状背鳍、臀鳍、腹鳍、胸鳍、尾鳍的鳍条数分别为6~12、9~15、10~24、20~28、23~33;具有1条侧线;第1鳃弓鳃耙数为15~18。斑点鳟为典型的肉食性鱼类,其消化系统结构特征为口咽腔较小,颌齿发达;食道短粗;胃发达,呈V形,分化明显;肠在腹腔内呈两个盘曲,肠长/体长为0.503±0.09;幽门盲囊数为48~72个。【结论】该实验结果可为斑点鳟的消化生理研究以及养殖管理提供科学的理论依据。     

Synthesis and characterization of carbon-bridged bis(phenolate) lanthanum alkoxides and their catalytic behavior for the polymerization of L-lactide

Four lanthanum alkoxides stabilized by a carbon-bridged bis(phenolate) ligand were synthesized and their catalytic behavior for the ring-opening polymerization of L-lactide was explored. Reactions of [(MBMP)LaCp(THF) 2 ] (MBMP 2 = 2,2′-methylene-bis(6-tert-butyl-4-methyl phenoxo)) with HOCH 2 Ph, HOCH 2 CF 3 , HOCH(CH 3 ) 2 , and HOCH 2 CH 2 N(CH 3 ) 2 , respectively, in a 1:1 molar ratio in THF gave the dimeric lanthanum alkoxo complexes [(MBMP)Ln(μ-OR)(THF) 2 ] 2 (OR = OCH 2 Ph(1), OCH 2 CF 3 (2), OCH(CH 3 ) 2 (3), OCH 2 CH 2 N(CH 3 ) 2 (4)]. These complexes were well characterized, and the definitive molecular structure of complex 1 was determined. It was found that complexes 1 to 4 are efficient initiators for the ring-opening polymerization of L-lactide. The structure of the alkoxo groups has a significant effect on the catalytic behavior, and complex 2 can initiate L-lactide polymerization in a controlled manner.     

Convergence in the<Emphasis Type="Italic">r</Emphasis>-th mean and the Marcinkiewicz type weak law of large numbers for weighted sums of<Emphasis Type="Italic">L</Emphasis><Subscript>q</Subscript>-mixingale arrays

L _r convergence and convergence in probability for weighted sums ofL _q-mixingale arrays have been discussed and the Marcinkiewicz type weak law of large numbers forL _q-mixingale arrays has been obtained. Foundation item: Supported by the National Natural Science Foundation of China (10071058) Biography: Gan Shi-xin (1939-), male, Professor, research direction; martingale theory, probability limiting theory and Banach space geometry theory.     

FERE法研究M_xO_y(M=Sc、Ti、V、Cr、Mn、Fe、Co、Ni)形成能

采用密度泛函理论(DFT)中的广义梯度近似法(GGA+U)对氧化物M_xO_y(M=Sc、Ti、V、Cr、Mn、Fe、Co、Ni)进行几何结构优化,然后计算其总能,根据形成能与总能的关系求出它们的形成能,再用FERE(Fitted Elemental-phase Reference Energies)方法对形成能进行修正。结果表明:修正后,每个单胞形成能相对实验值的平均绝对偏差由0.59 eV降低到0.46 eV,其中Ti-O、V-O、Co-O和Ni-O化合物的形成能修正值更接近实验值;而其他元素氧化物的形成能修正值相对于实验值的平均绝对偏差略有增大。     

Solid-phase preparation and characterization of Chitosan

0　IntroductionChitosanhasbeenwidelyusedinpharmaceu tical,agriculturalandindustrialfieldbe causeofitsintriguing properties[1 ] .Chemicalmethodstopreparechitosanfromchitinhavebeenbroadlystudiedincludingsolutionmethod ,meltedalkalinemethod,microwavesemi drymethod ,improvedLinelbergmethod ,dissolution precipita tionmethodandsoon ,inwhichalkalinewasallusedasthecatalyst[2 ] .Biologicalmethodwasapromisingwayinthatitproducedlittleenviron mentalpollutionanditsreactionconditionsweremild .However,thism…     

Well-defined bis（phenolate） lanthanide methoxides as efficient initiators for the polymerization of cyclic carbonate and lactide

Lanthanide methoxides supported by carbon-bridged bis(phenolate) ligands 2,2′-methylene-bis(6-tert- butyl-4-methylphenoxo) (MBMP2-) [(MBMP)Ln( μ-OMe)(THF)2]2 (Ln = Nd (1), Yb (2)) were synthesized in high yields by the protolysis reaction using (C5H5)3Ln(THF) as starting materials, and complex 1 was structurally characterized. The coordination geometry around the center metal can be best described as a distorted octahedron. Complexes 1 and 2 were shown to be efficient initiators for the ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) and L-lactide. The mechanism of DTC polymerization was explored by the end group analysis of the oligomer.     

Davis’s inequalities for two-parameter Banach space valued strong martingales and geometrical properties of Banach spaces

In this paper we investigated theL ₁ norm inequalities of theP square and the maximal functions of two-parameterB-valued strong martingales, which can be applied to characterizep-smoothness andq-convexity of Banach spaces. Foundation item: Supported by the National Natural Science Foundation of China Biography: YE Chen (1974-), male, Master candidate, Research interest is in stochastic processes.     

微波辅助合成聚天冬氨酸

借助微波辅助手段,以天冬氨酸（A）为原料,在均三甲苯和环丁砜混合溶剂中,以磷酸（体积分数为85%）为催化剂进行聚合反应。考察了催化剂用量、微波功率、反应温度和反应时间等因素对聚琥珀酰亚胺（PSI）的产率以及分子量的影响;进一步对PSI进行水解反应,并用红外光谱对水解产物进行结构表征。结果表明：借助微波辅助加热手段,使得聚合反应时间大大缩短,由传统热缩合反应的3～5h缩短为20min左右,反应效率明显提高;随催化剂用量的增加,PSI的产率增加,分子量降低,但过多的催化剂存在会导致产率下降;微波功率增大,PSI产率与分子量均呈下降趋势;在微波作用下,聚合反应温度（170～200℃）明显低于传统热缩合聚合的温度,并随着温度的升高和反应时间的延长,PSI的产率和聚天冬氨酸（PASP）分子量均呈现明显增加。在合适的条件下,可制备出数均分子量为6000～20000,分子量分布为1.3～2.4的PASP产物。     

臭氧水对草莓及拟盘多毛孢影响的研究

通过组织分离纯化和分子生物学鉴定,明确了引起草莓叶部新病的致病菌为拟盘多毛孢。以喷洒清水为空白对照,利用不同质量浓度的臭氧水直接喷洒致病菌和生长期的草莓植株,研究臭氧水对致病菌和草莓植株的浓度效应,结果显示：低浓度臭氧水（0.5~0.8 mg·L^-1）对草莓植株的生理生态变化和致病菌的生长影响较小;中浓度臭氧水（2.2~2.5 mg·L^-1）可以显著抑制致病菌的生长,并促进草莓植株的生长;高浓度臭氧水（4.0~4.3 mg·L^-1）可以很好地抑制致病菌的生长,但对草莓叶片有较严重的腐蚀作用。因此,中浓度（2.2~2.5 mg·L^-1）是喷洒草莓的最适臭氧水浓度。     

Core-shell microstructure formed in the ternary Fe-Co-Cu peritectic alloy droplet

The metastable liquid phase separation occurs in the ternary Cu₅₀Fe_37.5Co_12.5 peritectic alloy droplets during free fall. The separated alloy melt rapidly solidifies and evolves core-shell microstructure composed of L₁(Cu) and L₂(Fe,Co) phases. Based on the determination of the phase transition temperature, the core-shell microstructure evolution, the interfacial energy, the temperature gradient and the Marangoni migration are analyzed. The interfacial energy of the separated liquid phase increases with the decrease of the temperature. The temperature gradient changes from large to small along the radius direction from inside to outside in the alloy droplet. The Marangoni force (F _M) acting on the micro-droplet of L₂(Fe,Co) phase increases with the increase of the size of the L₂(Fe,Co) phase, and decreases with the increase of undercooling. Driven by F _M, the micro-droplet of L₂(Fe,Co) phase migrates from outside to inside in the alloy droplet, collides and coagulates each other during migration, and then forms different types of core-shell microstructures. Supported by the National Natural Science Foundation of China (Grant Nos. 50121101, 50395105) and NPU Youth Scientific and Technological Innovation Foundation (Grant No. W016223)     

Studies on reduced extent method for inhibited thermokinetics of enzyme-catalyzed reaction

The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distinguishing inhibition type was given and the methods for calculating kinetic parameters,K _M,K _i andv _m were suggested. This theory was applied to inverstigate the inhibited thermokinetics of laccase-catalyzed oxidation ofo-dihydroxybenzene bym-dihydroxybenzene. The experimental results show the inhibition belongs to reversible competitive type,K _M=6.224×10⁻³ mol·L⁻¹,K _i=2.363×10⁻² mol·L⁻¹. Xiong Ya: born Sep. 1961, Ph. D. graduate student. Curent research interest is in biothermochemistry research Supported by the National Natural Science Foundation of China     

拟穴青蟹形态性状与性腺重量的相关分析

选取16月龄池塘养殖雌性拟穴青蟹(Scylla paramamosain)67只,测量其头胸甲长(X1)、头胸甲宽(X2)、腹部宽(X3)、体重(X4)和性腺重(Y),利用相关分析和通径分析方法计算形态性状对性腺重的相关系数、通径系数和决定系数,明确影响拟穴青蟹性腺重的主要形态性状,为拟穴青蟹选育提供理论依据和技术支持.结果表明,形态性状与性腺重相关性极显著(P＜0.01),其中体重对性腺重的直接影响和决定程度最大(0.736,54.2％),腹部宽次之,头胸甲长最小.通过头胸甲长、腹部宽和体重估计性腺重的多元回归方程为:Y=14.467-1.556X1+1.626X3+0.245X4 (R2=0.499).