Probing the micellization of diblock and triblock copolymers of poly(L-lactide) and poly(ethylene glycol) in aqueous and NaCl salt solutions

The micelle formation of a series of amphiphilic block copolymers in aqueous and NaCl solutions was studied by a fluorescent probe technique using pyrene as a 'model drug'. These copolymers were synthesized from poly (ethylene glycol) (PEG) and L-lactide by a new calcium ammoniate catalyst. They had fixed PEG block lengths (44, 104 or 113 ethylene oxide units) and various poly(L-lactide) (PLLA) block lengths (15-280 lactide units). The critical micelle concentration (cmc) was found to decrease with increasing PLLA content. The distinct dissimilarity of the cmc values of diblock and triblock copolymers based on the same block length of PEG provided evidence for the different configurations of their micelles. It was also observed that the introduction of NaCl salt significantly contributed to a decrease in the cmcs of the copolymers with short PEG and PLLA blocks, while it had less influence on the cmcs of copolymers with long PEG or PLLA blocks. The dependence of partition coefficients ranging from 0.2x10(5) to 1.9x10(5) on the PLLA content in the copolymer and on the micelle configuration was also discussed.

Electrochemical properties of amorphous and icosahedral quasicrystalline Ti45Zr35Ni17Cu3 powders

Ti45Zr35Ni17Cu3 amorphous and single icosahedral quasicrystalline powders were synthesized by mechanical alloying and subsequent annealing at 855 K. Microstructure and electrochemical properties of two alloy electrodes were characterized. When the temperature was enhanced from 303 to 343 K, the maximum discharge capacities increased from 86 to 329 mAh g(-1) and 76 to 312 mAh g(-1) for the amorphous and quasicrystalline alloy electrodes, respectively. Discharge capacities of two electrodes decrease distinctly with increasing cycle number. The I-phase is stable during charge/discharge cycles, and the main factors for its discharge capacity loss are the increase of the charge-transfer resistance and the pulverization of alloy particles. Besides the factors mentioned above, the formation of TiH2 and ZrH2 hydrides is another primary reason for the discharge capacity loss of the amorphous alloy electrode.

An approach for fabricating self-assembled monolayer of Ag nanoparticles on gold as the SERS-active substrate

In this paper, an approach for fabricating an active surface-enhanced Raman scattering (SERS) substrate is adopted. This approach is based on the assembling of silver nanoparticles film on gold substrate. Rhodamine 6G (R6G) and p-aminothiophenol (P-ATP) were used as probe molecules for SERS experiments, showing that this new active substrate has sensitivity to SERS response. Tapping-mode atomic force microscopy (AFM) was also used to investigate the surface morphology following the fabricating process of the active SERS substrate, which showed that large quantities of silver nanoparticles were uniformly coated on the substrate.

Analysis of norditerpenoid alkaloids extracted from Aconitum sinomantanum Nakai by electrospray ionization tandem mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) was applied simultaneously in determining norditerpenoid alkaloids from the roots of Aconitum sinomantanum Nakai ( RAS) based on molecular mass information. The tandem mass spectra (ESI-MSn) provided the alkaloidal structural information, through which the existence of these alkaloids was further confirmed. Accordingly, six known norditerpenoid alkaloids were simultaneously determined on the basis of their ESI-MSn spectra. Furthermore, based on the diagnostic fragmentation pathways of alkaloidal MSn, a rapid method for direct detection and characterization of alkaloids from an ethanolic extract of RAS was described.

Electrochemical behavior of alpha-Keggin-type nanoparticles, Co(en)(3)(PMo12O40), in polyethylene glycol

The electrochemical behavior of alpha-Keggin-type nanoparticles, Co(en)(3)(PMo12O40) (abbreviated as PMo12-Co), have been studied in poly(ethylene glycol) for four different molecular weights (PEG, average MW 400, 600, 1000, and 2000 g mol(-1)) and containing LiClO4 (O/Li=100/1) supporting electrolyte. The diffusion coefficients of the PMo12-Co nanoparticles were determined using a microelectrode by chronoamperometry for PEG of different molecular weights that were used to describe the diffusion behavior of PMo12-Co nanoparticles in different phase states. Moreover, the conductivity of the composite system increases upon addition of PMo12-Co nanoparticles, which was measured by an a.c. impedance technique. FT-IR spectra and DSC were used to follow the interactions of PEG-LiClO4-PMo12-Co, and well described the reason that the PMo12-Co nanoparticles could promote the conductivity of the PEG-LiClO4-PMo12-Co system.

氟化吡唑啉蓝色电致发光器件的制备

自从Tang等[1]首次报道了多层有机电致发光器件以来,人们研究了大量的新型材料[2,3],其中较吸引人的方法是将高量子产率的荧光染料掺杂于传输层中制备电致发光器件 [4～9].三芳基吡唑啉化合物具有较高的荧光产率和蓝色发射特性.这些化合物具有分子内电荷传输性能,在激发状态下分子可发生扭曲形成电子给体 -受体结构[10],因此在 EL器件制备过程中既可以作为载流子传输材料,又可以作为发光材料来应用.虽然吡唑啉类化合物在固态下具有空穴传输特性 [11],也有较高的荧光产率,但它们的玻璃转化转变温度较低,在制备EL器件时,如单独作为传输层或发射层时 ,该类材料易于结晶,从而使得器件的性能快速衰减.如果将它们分散于聚合物等主体中,就会避免重结晶问题.我们在三苯基吡唑啉中引入强吸电子基团CF3,导致分子的刚性增强和荧光强度增加,熔点升高.将氟化三苯基吡唑啉(FTPP)作为发光中心制作了两类 EL器件,均获得蓝光发射.

Modern spectral estimation of ICP-AES

The inductively coupled plasma atomic emission, spectrometry (ICP-AES) and its signal characteristics were discussed using modem spectral estimation technique. The power spectra density (PSD) was calculated using the auto-regression (AR) model of modem spectra estimation. The Levinson-Durbin recursion method was used to estimate the model parameters which were used for the PSD computation. The results obtained with actual ICP-AES spectra and measurements showed that the spectral estimation technique was helpful for the better understanding about spectral composition and signal characteristics.

稀土氧氯化物在冰晶石氧化铝熔体中的溶解度

用等温饱和法测定了单一稀土氧氯化镧 (LaOCl)和混合稀土氧氯化物 (REOCl)在冰晶石 (Na3AlF6 ) 氧化铝 (Al2 O3)熔体中的溶解度。结果表明 :LaOCl和REOCl的溶解度变化规律一致 ,即其溶解度随温度升高而增大 ;随着冰晶石分子比增加而增大 ;当有 4 0 % (质量分数 )Al2 O3存在时 ,其溶解度相应减少。

新型抗爱滋病药物吡喃酮类化合物的三维定量构效关系研究

吡喃酮类化合物是抗爱滋病的一类新药， 本文用CoMFA(Comparative Molecular Field Analysis)方法对19个吡喃酮类化合物的三维构效关系进行了研究， 较详细地探讨了分子的重叠方式， 并选用了其他有关的一些最优条件， 得到满意的结果。

无机—有机纳米复合材料

无机—有机纳米复合材料综合了无机、有机和纳米材料的优良特性，将会形成重要的多功能新材料，具有良好的机械、光、电和磁等功能特性，在许多领域具有广阔应用前景。本文对近年来无机—有机纳米复合材料的制备、性质、应用等方面的发展进行了评述。

Abnormal IR spectra of CO adsorbed on the surface of glass carbon electrode modified with polypyrrole film with platinum microparticles

Abnormal IR spectra of CO adsorbed at the surface of glass carbon electrode modified with polypyrrole film with Pt microparticles are reported.

Melt functionalization of ethylene-propylene copolymer: Structural investigation

An ethylene-propylene copolymer (EPM) has been functionalized with acrylic acid (AA) by means of a radical-initiated melt process. Different degrees of grafting have been obtained by varying the overall composition of the reaction mixture. The influence of the grafting degree on the structure has been investigated by differential scanning calorimetry (DSC), Fourier-transform infrared analysis (FTIR), and wide-angle x-ray scattering (WAXS) techniques. The results of the structural investigations suggest that the grafting preferentially occurs onto the ethylene sequences of EPM. After acrylic acid was grafted onto EPM, the grafted AA acted as nucleation agent; it caused an increase of crystallization temperature of propylene sequences of EPM-g-AA.

聚甲基丙烯酸甲酯－聚四氢呋喃两嵌段共聚物／聚四氢呋喃共混体系的相容性和结晶行为

报道了对嵌段共聚物结晶型共混体系结晶行为的研究．通过对聚甲基丙烯酸甲酯－聚四氢呋喃两嵌段共聚物／聚四氢呋喃共混体系的研究，我们发现１．微相分离结构的存在，可使相容的这类体系形成多种特殊的结晶形态；２．共混体系的相容性可以方便地由其结晶行为来判断；３．共混体系中共聚物的结晶能力显著提高．这些特点都明显不同于一般的聚合物共混体系．

高效毛细管电泳安培检测的进展

本文对高效毛细管电泳电化学检测方法中的安培检测进行了评述.安培检测具有灵敏度高、选择性好的特点.安培检测根据毛细管内径的大小有离柱安培检测和柱端安培检测.近年来脉冲安培分析法、化学修饰电极也已被引入毛细管电泳电化学检测.

两类带选择激发脉冲激发轮廓的模拟比较

本文用Ｂｌｏｃｈ方程模拟了ＢＵＲＰ族脉冲￣［１－３］和高斯串族脉冲￣［４，５］（Ｇａｕｓｓｉａｎｐｕｌｓｅｃａｓｔａｌｅｓ）的激发轮廓，系统地比较了这两类脉冲的选择性及其对射频场非均匀性的依赖性，给出了选择性最佳的脉冲。