超支化聚硅氧烷的紫外光固化行为及固化动力学研究

采用等温差示光量热技术(DPC)研究了超支化聚硅氧烷的紫外光固化行为及固化动力学. 探索了引发剂浓度、 光强度、 聚合温度和环境气氛对固化行为的影响规律. 研究结果表明, 增加光引发剂浓度和光强度及提高环境温度均可提高其固化速率和双键最终转化率. 在空气中固化时存在氧阻聚现象, 增大光强度可以显著缩短诱导期. 运用带扩散因子的自催化固化动力学模型研究了其光固化动力学, 计算出特定条件下的光固化动力学参数, 反应总级数约为6—7, 表观活化能为9.95 kJ/mol. 通过超支化聚合物与两种结构类似的低官能度单体光固化行为的对比, 研究了超支化聚合物固化行为与其分子结构的关系, 发现由于超支化大分子的独特结构, 在固化初始阶段便产生凝胶, 因此双键的最终转化率偏低.     

INFLUENCE OF PLASMA DENSITY ON NUCLEATED DENSITY OF DIAMOND

The predeposition method for mereasing CH_4 concentration ininitial stage of diamond synthesis by plasma chemical vapor deposition.isused to enhance nucleated density of diamond films.The plasma parametersare diagnosed in situ using the Langmuir double probe.The relation betweenplasma ion density and nucleated densitv of diamond is revealed Increasingplasma ion density results in enhancement of nucleated density of diamondobviously     

聚乙二醇嵌段树枝状聚赖氨酸共聚物的合成及其基因载体研究

采用液相多肽合成法制备得到窄分子量分布、结构可控的生物相容性聚乙二醇嵌段共聚树枝状聚赖氨酸阳离子功能大分子(PEG-b-Dendritic PLL). 运用¹H NMR核磁共振、凝胶电泳以及荧光淬灭滴定手段对所得阳离子两嵌段大分子的化学结构及其与质粒DNA (pDNA)结合作用与复合行为进行了研究. 结果表明聚乙二醇嵌段树枝状聚赖氨酸与pDNA分子可以在缓冲溶液中形成稳定的胶束, pDNA与阳离子树枝赖氨酸嵌段通过静电相互作用形成胶束核, 其水溶性聚乙二醇嵌段形成水溶性胶束壳, 提高了阳离子大分子/pDNA复合胶束的稳定性. 同时发现随着阳离子嵌段树枝状赖氨酸代数的增加, 阳离子两嵌段大分子与pDNA的结合作用增强, 有利于其作为基因转染生物功能载体的应用.     

聚合物与有机染料多层复合膜电致发光颜色的直流电压调制

聚合物与有机染料多层复合膜电致发光颜色的直流电压调制马於光，薛善华，黄劲松，田文晶，刘式墉，沈家骢，刘晓冬（吉林大学分子光谱与分子结构开放实验室，集成光电子学国家重点实验室，长春，１３００２３）（白求恩医科大学，长春，１３００２３）关键词聚合物，发光...     

Nd-Fe-B alloy-densified agarose gel for expanded bed adsorption of proteins

Novel dense composite adsorbents for expanded bed adsorption of protein have been fabricated by coating 4% agarose gel onto Nd-Fe-B alloy powder by a water-in-oil emulsification method. Two composite matrices, namely Nd-Fe-B alloy-densified agarose (NFBA) gels with different size distributions and densities, NFBA-S (50-165 microm, 1.88 g/ml) and NFBA-L (140-300 microm, 2.04 g/ml), were produced. Lysozyme was used as a model protein to test the adsorption capacity and kinetics for the NFBA gels modified by Cibacron blue 3GA (CB-NFBA gels). Liquid-phase dispersion behavior in the expanded beds was examined by measurements of residence time distributions, and compared with that of Streamline SP (Amersham-Pharmacia Biotech, Sweden). The dependence of axial mixing in the expanded beds on flow velocity, bed expansion degree. settled bed height, and viscosity of liquid phase was investigated. Breakthrough curves of lysozyme in the expanded beds of the CB-NFBA gels were also examined. The dynamic binding capacity at 5% breakthrough was 23.3 mg/ml matrix for the CB-NFBA-S gels, and 16.7 mg/ml matrix for the CB-NFBA-L, at a flow velocity of 220 cm/h. The results indicate that the NFBA gels are promising for expanded bed adsorption of proteins.     

Exact solution of supercritical axially moving beams: symmetric and anti-symmetric configurations

We present an exact solution for supercritical configurations of axially moving beams with arbitrary boundary conditions. We take into account the geometric nonlinearity of the traveling beams in supercritical regime, and the nonlinear buckling problem is analytically solved. A closed-form solution for the supercritical configuration in terms of the axial speed is obtained. Some typical boundary conditions, such as fixed-fixed, fixed-pinned and pinned-pinned, are discussed. More importantly, based on the exact solution, we found a new anti-symmetric configuration for the fixed-fixed axially moving beams. The traveling beam may vibrate around the new anti-symmetric configuration at sufficiently high traveling speeds. A good accuracy of the solution is confirmed by a comparison with the data available in the literature, and with our own numerical results.     

An optical study of the D-D neutron irradiation-induced defects in Co-and Cu-doped ZnO wafers

Room-temperature photoluminescence and optical transmittance spectroscopy of Co-doped(1×1014,5×1016,and 1×1017cm-2) and Cu-doped(5×1016cm-2) ZnO wafers irradiated by D-D neutrons(fluence of 2.9×1010 cm-2) have been investigated.After irradiation,the Co or Cu metal and oxide clusters in doped ZnO wafers are dissolved,and the wu¨rtzite structure of ZnO substrate for each sample remains unchanged and keeps in high c-axis preferential orientation.The degree of irradiation-induced crystal disorder reflected from the absorption band tail parameter(E0) is far greater for doped ZnO than the undoped one.Under the same doping concentration,the Cu-doped ZnO wafer has much higher irradiation-induced disorder than the Co-doped one.Photoluminescence measurements indicate that the introduction rate of both the zinc vacancy and the zinc interstitial is much higher for the doped ZnO wafer with a high doping level than the undoped one.In addition,both crystal lattice distortion and defect complexes are suggested to be formed in doped ZnO wafers.Consequently,the Co-or Cu-doped ZnO wafer(especially with a high doping level) exhibits very low radiation hardness compared with the undoped one,and the Cu-doped ZnO wafer is much less radiation-hard than the Co-doped one.     

Relation between Airy beams and triple-cusp beams

Airy beams and triple-cusp beams are two kinds of accelerating beams. The propagation characteristics and internal topological structures of accelerating Airy beams are well understood because of the developed mathematical theory about Airy function. However, limited information is available about the optical characteristics of accelerating triple-cusp beams. In this work, the relationship between Airy beams and triple-cusp beams is examined theoretically and experimentally. Results reveal some important optical characteristics of triple-cusp beams based on the optical characteristics of Airy beams. These findings are expected to provide a foundation for future applications of triple-cusp beams.     

Triphenylphosphine-m-sulfonate/carbon tetrabromide as an easily recoverable catalyst system for the efficient synthesis of xanthene and xanthenone derivatives under solvent-free conditions

A solid complex,readily prepared from commercially available sodium triphenylphosphine-m-sulfonate（TPPMS） and carbon tetrabromide,can be used as an easily recoverable and reusable catalyst system for one-pot condensation of 2-naphthol with aldehydes to construct 14-aryl（alkyl）-14H-dibenzo[a j]-xanthene derivatives and one-pot condensation of 2-naphthol with aldehydes and cyclic 1 3-dicarbonyl compounds to construct 12-aryl（alkyl）-8 9 10 12-tetrahydrobenzo[a]xanthen-11-one derivatives.