注碳二氧化硅中高能重离子辐照效应研究

本论文工作采用“低能离子注入+高能重离子辐照”实验方法，通过建立注 碳二氧化硅（SiO2）中结构变化和新结构形成与高能重离子辐照参数的关系，比 较系统地研究了注碳SiO2中高能重离子辐照效应， 并对辐照效应产生机理进行了 初步探讨。 实验中，先将120keV的C离子注入SiO2样品，再用Xe、Pb、U等多种高能 重离子辐照，然后用FTIR、Raman谱和TEM等分析技术对样品进行表征。 实验结果表明， 高能离子辐照注碳非晶SiO2在注碳区形成管状径迹， 在高能 离子引起的离子径迹及其附近区域形成了SiC、 碳团簇、 SiOC结构和CO/CO2分子 并观察到了局域纳米晶化现象，形成的 SiOC 和 SiC 具有链式和笼式结构。新结 构的形成与碳离子注入剂量、高能离子辐照剂量、电子能损以及总沉积能量密度 有关，并存在相应的阈值。根据实验结果并结合热峰模型，我们认为高能重离子 辐照可能在注碳SiO2中引起了一系列化学反应， 其驱动力来自于强电子激发引起 的热峰过程。研究结果还表明，“低能离子注入+高能重离子辐照”是合成具有 特殊功能材料的一种有效手段，通过选择合适的高能重离子辐照，实现有选择结 构相变，可以合成新型功能材料。

高能kr离子辐照聚合物膜的潜径迹及其辐照降解特性的研究

本文简要叙述了快重离子在固体材料，特别是聚合物材料中引起的强电子激发效应研究的基本理论、发展历史和研究现状。描述了在兰州重离子加速器上完成的25 MeV/u 86Kr离子辐照叠层聚对苯二甲酸乙二醇酯膜（PET）和聚碳酸酯（PC）膜的实验及结果分析。应用傅立叶红外变换光谱（FT-IR）及X-射线衍射分析（XRD）方法研究了在不同电子能损及不同注量辐照条件下，高能Kr离子在聚合物PET和PC潜径迹中引起的的损伤效应。结果表明：高能Kr离子在聚合物PET、PC膜引起的损伤主要是由于辐照引起的断键及键的重组产生的官能团的降解及非晶化过程，损伤截面存在电子能损阈值，且与官能团的结构有关。 对PET的傅立叶红外变换光谱分析结果给出，电子能损为7.25 keV/nm时，对应官能团吸收峰794 cm-1, 849 cm-1, 1021 cm-1, 1341 cm-1, 1410 cm-1, 1505 cm-1,的损伤截面半径分别为：3.63 nm, 4.70 nm, 4.58 nm, 3.54 nm, 5.17 nm, 5.32 nm。X-射线衍射分析结果表明，PET的非晶化转变截面随离子注量和电子能损的增大而增加，（100）衍射峰的相对强度I/I0随离子注量的增加而指数衰减，对应电子能损为6.62, 6.93, 7.25 keV/nm，其相应的非晶化半径分别为4.86, 5.64, 6.77 nm。 对PC的傅立叶红外变换光谱分析表明，当电子能损比较小，大多数官能团的红外吸收无明显变化，直到当辐照注量为2×1012 ions/cm2 且电子能损比较大时，其绝对吸收强度才发生明显的改变。电子能损为6.37 keV/nm 时，对应官能团吸收峰为519 cm-1, 605 cm-1, 724 cm-1, 1014 cm-1，其损伤截面分别为：13.12, 45.40, 50.21, 56.28 nm2

重离子辐照普通小麦间接效应的研究

应用不同能量、不同剂量的碳离子和氧离子加照普通小麦，研究其M1代和M2代的生物学（形态）性状、染色体畸变率及微核率、生理生化和DNA分子等方面的变化。并对这些变化的生物学机理进行了探讨，结果如下：1.75MeV/u~(16)O~(8+)离子经过适当降能后注入小麦种子的不同部位和贯穿整个种子，对其M1代幼苗的可溶性蛋白质组分以及电脉中不同区段蛋白质组分相对含量加以分析，结果表明：1）同对照相比，随着辐照剂量的增加，所有辐照材料（包括贯穿和注入）第二区段（分子量较高区段）蛋白质组分的相对含量下降；而第五区段（分子量最小区段）蛋白质组分的相对含量升高。2）种子的贯穿处理，同时也引起第一区段（分子量最高区段）和第三区段蛋白质组分相对含量的下降以及第四区段的升高；其中第三、四区段的变化明显区别于注入效应。3）注入胚和胚乳的区别在于后者第一区段蛋白质组分相对含量的较大下降和第五区段的较大提高。4）小剂量辐照的材料，可溶性蛋白质组分的变化异常，可能与低剂量辐射兴奋效应有关。2.碳离子注入胚乳引起胚的后代发生变异，是典型的重离子诱变产生间接效应的结果。主要表现为：1）M1代的生物学性状、幼苗的抗氧化酶活性、MDA含量、蛋白质含量和染色体畸变率及微核率等发生了较大的变化。2）对其矮杆变异株和紫色茎杆突变体（M2）和RAPD和AFLP分子鉴定等研究，结果显示了矮杆变异体和紫色茎杆突变体的DNA序列发生了改变，而非仅仅产生生理损伤；同一种变异体或突变体，在M2代单株间也存在着明显的差异，表明它们可能还处于分离状态。于是，将M2代以上高代再种，以观察遗传能否稳定。3.重离子辐照普通小麦种子的M1代正常（它们可以完成生长发育的过程）植株同对照材料做正、反交，获得染色体组等来源不同的材料。接着对对照、M2代和正、反交材料DNA进行RAPD和AFLP多态性研究，并将实验结果作统计分析，结果表明：在细胞结构层次上，染色体组作为靶物质，产生的直接效应主要引起随机突变；而非染色体组的细胞组成的间接效应主要引起非随机突变。

带电粒子辅照生物分子改性的研究

本文是从超低能（110KeV）、低能（1-20MeV/u）重离子注入生物材料引起突变效应及其机理研究中产生的新生长点，从辐射化学角度通过对脱氧核糖核酸（DNA）、蛋白质以及组成DNA和蛋白质的基本单元的辐照损伤的调研，从物理角度对带电粒子（包括质子和重离子）高低传能线密度（LET）辐射与X射线、γ射线等低LET辐射加以比较，提出了采用带电粒子注入生物分子改性研究的新思路；并在此基础上，开展了一些实验工作。 在用质子束注入的甘氨酸水溶液的辐照产物的分析实验中，用气相色谱和质谱（GC-MS）联用技术的分析，得到了不同于X射线、γ-射线辐照甘氨酸水溶液的辐照产物——甘氨酰甘氨酸（甘甘二肽），并根据有关文献提出了产生这种产物的可能机理。从而从辐射化学方面为带电粒子对生物分子的辐照损伤反应提供了进一步的认识，也为从辐射生物学角度解释带电粒子对蛋白质这样大分子的作用机制提供了新的依据。

Synthesis of covalently bonded cellulose derivative chiral stationary phases with a bifunctional reagent of 3-(triethoxysilyl)propyl isocyanate

A bifunctional reagent of 3-(triethoxysilyl)propyl isocyanate (TEPI) was initially adopted as a spacer reagent to prepare the bonded types of chiral stationary phases (CSPs) with cellulose derivatives. The silica-based CSPs were chemically prepared with non-regioselective and regioselective approaches and their chiral resolving capabilities were evaluated in terms of HPLC resolution of test enantiomers. It was observed that the chiral recognition capabilities of the non-regioselectively prepared CSPs were influenced by the amount of TEPI used. And also, the regioselectively prepared CSP generally showed a slightly higher resolution power than the non-regioselectively prepared CSP, while the non-regioselective procedures were highly advantageous to rapid preparation. In addition, chiral recognition of the prepared CSPs was affected by the properties of the used silica matrices. (C) 2003 Elsevier B.V. All rights reserved.

北方干旱地区农业水环境变化与适应对策

我国北方干旱地区 ,少雨干旱是限制农业可持续发展的障碍因子。为实现该地区的农业可持续发展 ,促进环境优化、本文在全面分析北方干旱地区水资源状况基础上 ,对节水农业的措施和对策提出了方向和具体手段

Numerical Simulation of Reactive Extrusion Processes for Activated Anionic Polymerization

In order to deal with the complicated relationships among the variables of the reactive extrusion process for activated anionic polymerization, a three-dimensional equivalent model of closely intermeshing co-rotating twin screw extruders was established. Then the numerical computation expressions of the monomer concentration, the monomer conversion, the average molecular weight and the fluid viscosity were deduced, and the numerical simulation of the reactive extrusion process of Styrene was carried out. At last, our simulated results were compared with Michaeli's simulated results and experimental results. (C) 2007 Elsevier B.V. All rights reserved

Phase separation and crystallization in a melt-spun Ti45Zr35Ni17Cu3 alloy

Structure and crystallization behavior of amorphous and quasicrystalline Ti45Zr35Ni17Cu3 alloy have been studied. DSC trace of the amorphous alloy obtained during continuous heating to 1300 K shows distinctly an exothermic peak and two endothermic peaks.

淀粉-丙烯酰氧乙基三甲基氯化铵接枝共聚物的制备与表征

采用过硫酸铵(APS)为引发剂,将玉米淀粉与丙烯酰氧乙基三甲基氯化铵(DAC)接枝聚合,制备了一系列分子中含有阳离子季铵基团的淀粉——DAC接枝共聚物。研究了单体用量、引发剂用量、反应温度和反应时间对接枝体系阳离子度的影响,探讨了过硫酸铵引发淀粉接枝DAC共聚反应的基本规律。并用FTIR、X-ray和1H-NMR等表征手段对接枝共聚物进行了结构分析。

The investigation of exfoliation process of organic modified montmorillonite in thermoplastic polyurethane with different molecular weights

Cloisite 30B (30B) was melt-mixed with two kinds of thermoplastic polyurethane (TPU) with different molecular weights to discern the roles of molecular diffusion and shear in the exfoliation process. The higher level of exfoliation was achieved in TPU matrix with higher molecular weight due to the appropriate viscosity. In order to have an insight into the mechanism of exfoliation, the degree of dispersion and exfoliation of 30B was characterized by wide angle X-ray diffraction and transmission electron microscopy. The layers of 30B were exfoliated via a slippage process, which was also observed in polyamide 12 nanocomposites recently.

Preparation and characterization of poly(piperazineamide) composite nanofiltration membrane by interfacial polymerization of 3,3 ',5,5 '-biphenyl tetraacyl chloride and piperazine

Most nanofiltration (NF) membranes are composite and have a polyamide thin film prepared by interfacial polymerization. Their performances mainly correlate the structure of the thin film and monomers used for its preparation. In this work, a novel thin-film composite (TFC) nanofiltration membrane was successfully prepared from 3,3',5,5'-biphenyl tetraacyl chloride (mm-BTEC) and piperazine (PIP) through interfacial polymerization. Attenuated reflectance infrared (ATR-IR) and X-ray photoelectronic spectroscopy (XPS) were used to characterize the chemical composition of the membrane surface. The membrane performance was optimized by studying preparation parameters including monomer concentration, reaction time, and pH of aqueous phase.

Effect of gamma-radiation on the thermal and mechanical properties of a commercial poly(butylene adipate-co-terephthalate)

BACKGROUND: Poly(butylene adipate-co-terephthalate) (PBAT) has attracted wide interest as a biodegradable polymer. However, its use is restricted in certain applications due to its low melting point.RESULTS: PBAT was treated using gamma-radiation. The radiation features were analyzed using Soxhlet extraction, and the ratio of chain scission and crosslinking and gelation dose were determined using the classical Charlesby-Pinner equation. The results showed that PBAT is a radiation-crosslinkable polymer. The degree of crosslinking increased with increasing radiation dose; the relation between sol fraction and dose followed the Charlesby-Pinner equation. Differential scanning calorimetry analyses showed that the melting temperature (T-m) and the heat of fusion (Delta H-m) of PBAT exhibited almost no change in the first scan. The second scan, however, showed a decrease in T-m and Delta H-m. The glass transition temperature of irradiated PBAT increased with increasing radiation dose.

Effects of SEBS-g-BTAI on the morphology, structure and mechanical properties of PA6/SEBS blends

Styrene-b-(ethylene-co-1-butene)-b-styrene (SEBS) triblock copolymer functionalized with epsilon-caprolactam blocked allyl (3-isocyanate-4-tolyl) carbamate (SEBS-g-BTAI) was used to toughen polyamide 6 (PA6) via reactive blending. Compared to the PA6/SEBS blends, mechanical properties such as tensile strength, Young's modulus, especially Izod notched strength of PA6/SEBS-g-BTAI blends were improved distinctly. Both theological and FTIR results indicated a new copolymer formed by the reaction of end groups of PA6 and isocyanate group regenerated in the backbone of SEBS-g-BTAI. Smaller dispersed particle sizes with narrower distribution were found in PA6/SEBS-g-BTAI blends, via field emitted scanning electron microscopy (FESEM). The core-shell structures with PS core and PEB shell were also observed in the PA6/SEBS-g-BTAI blends via transmission electron microscopy (TEM), which might improve the toughening ability of the rubber particles.