X射线衍射分析非晶二氧化硅结构及其物化性质的研究

研究用不同水玻璃浓度合成的4个非晶沉淀二氧化硅样品的物化性质、近红外、热重差热行为。并用X射线衍射手段分析了非晶二氧化硅的结构参数,结果表明样品的短程有序范围在5～6个原子距离。最近邻配位数与最近邻原子距离的变化与样品的吸油值相一致,一定程度上反映了样品结构的紧密程度。     

Characterization of the Molecular Structural Changes Following Ion-Exchange Treatment of Zhundong Coal

Low-rank coal usually contains the highly exchangeable metallic species content. Due to this feature, ion-exchange treatment, which can load extra exchangeable metallic species into coal matrix, is widely used to investigate the behaviors of these species during thermal conversion. However, whether any structural changes of coals are caused during ion-exchange treatment process remains unknown. In this work, to examine structural changes during ion-exchange treatment and provide evidence on reliability of this treatment, multiple techniques were used to characterize the structural features of a Zhundong coal during ion-exchange treatment. The results show that the maximum weight loss of coal becomes smaller after ion-exchange treatment, which indicates that introduction of exchangeable sodium species makes coal matrix density more compact and enhances cross-linking structures. Meanwhile, compared with raw coal, the variation of oxygen forms in the demineralized and ion-exchanged coals is negligible because the maximum differences in content for C–O, C–O, and COO are 5.3, 6.9, and 5.9%, respectively. According to Fourier transform infrared spectra, the skeletal structures of Zhundong coal are also not influenced. Raman spectra show that during ion-exchange treatment, the relative proportions of amorphous carbon structures (particularly small aromatic ring systems with 3–5 fused benzene rings) and large aromatic ring systems (more than six rings) stay almost unchanged. In light of these results, ion-exchange treatment is suggested to result in slight structural changes and is reliable in coal research.     

Synthesis and anti-HIV activity of sulfated astragalus polysaccharide

Sulfated astragalus polysaccharide (sulfated astragalan, SA) was prepared by chemical modification of astragalus polysaccharide abstracted from an astragalus menbranceus used as a Mongolia herbal medicine. Anti-HIV activity of SA was assayed in vitro and the results indicated that the SA showing high anti-HIV activity and lower cytotoxity. Sulfation of astragalan was carried out by using sulfur trioxide-pyridine complex in a mixture of dimethylsulfoxide (DMSO) to give sulfated astragalan with degree of substitution (DS) of 1.14–1.20 and a number average molecular weight (M_n) of 1.27–1.46 × 10⁴. Copyright © 2003 John Wiley & Sons, Ltd.     

微晶酚酞富集-分光光度法测定痕量Zn(II)

建立了一种利用修饰有结晶紫(CV^＋)的微晶酚酞作为固态吸附剂分离富集溶液中痕量Zn(II)的新方法, 富集后的Zn(II)含量可直接用光度法测定. 控制一定条件, Zn(II)能与常见阳离子Ni(II), Cd(II), Al(III), Ca(II), Mg(II), Co(II), Mn(II), Cu(II), Pb(II), Fe(III)等完全分离, 且富集时基本不受, , Br^－, Cl^－, I^－,等阴离子影响. 微晶酚酞对Zn(II)的吸附容量为25.8 mg/g; 富集因数可达200倍, 回收率在97.7%～102%之间, RSD小于2.7%. 该方法已成功应用于实际水样中Zn(II)的富集测定, 结果令人满意.     

混沌中信号的投影滤波

根据混沌的确定性和几何结构特征,提出了预测性邻点选取方法和基于Delaunay三角化的邻点选取方法,改进了降低混沌中噪声的投影方法,建立了新的正交局部投影算法,给出了优化参数选择法则.这种方法成功地应用于提取Lorenz混沌中的微弱信号,在信噪比不低于-80dB条件下,能够准确提取信号信息.数值实验表明该投影滤波方法具有高度的稳定性和可靠性,是提取混沌中微弱信号的十分有效方法.     

泼尼松包合物的制备及其光谱分析鉴定

采用正交设计法,以泼尼松(PA)包合率作为考察指标,考察了搅拌时间,包合温度以及PA浓度对包合率的影响,达到筛选最佳制备工艺的目的。泼尼松与羟丙基β-环糊精的最佳包合条件为:PA浓度为8.5mg/mL,包合温度为70℃,包合时间为18h,并运用红外、紫外、薄层色谱及显微镜观测等多种鉴定方法对包合物进行了鉴定,结果表明:泼尼松与HP-β-CD成功进行了包合。     

ST-401薄塑料闪烁体中子能量响应测量技术研究

利用中国原子能科学研究院核工业放射性计量测试中心的5SDH-2串列加速器进行了ST-401薄塑料闪烁体的能量响应实验.选用T(p,n)³He反应和D(d,n)³He反应作为中子源，子源，中子束流采用复合屏蔽体进行准直，源强采用正比计数管和半导体望远镜进行监测，实验测量了厚度从0.16mm到2.00mm的八种规格薄闪烁体的能量响应曲线，对实验的结果的不确定度进行了分析.结果表明探测器的灵敏度随着晶体厚度的增加而增加，对于一定厚度的薄闪烁体，随着中子能量的增加，探测器的能量响应曲线坡度不大. 关键词： 塑料闪烁体 能量响应 正比计数器 半导体反冲质子望远镜     

记录飞秒级超快动态过程的脉冲数字全息技术

采用脉冲数字全息技术实现对飞秒级超快动态过程的数字显微全息记录.其中，全息记录系统将单脉冲分割成具有飞秒至皮秒量级时间延迟的角度相同的物光子脉冲序列和具有同样时间延迟的角度不同的参考光子脉冲序列，并以空间角分复用的方式在普通CCD的一帧图像上记录下包含多张子全息图的复合全息图，然后通过数字傅里叶变换和数字滤波的方法，分别再现出每张子全息图所记录的图像.通过对飞秒激光激发空气电离过程的全息记录，获得了具有飞秒时间分辨的等离子体形成和传播过程的动态图像. 关键词： 超短脉冲激光 飞秒全息 脉冲数字全息 空间角分复用     

归一化KLD系数及多维序列相关和同步的检测

提出了KLD系数和归一化KLD系数来刻画多维序列的相关结构, 以解决KLD维密度固有的局限性. 利用完全相关和完全不相关的多维序列, 导出KLD维密度的上界和下界函数, 进而导出KLD系数的上界和下界, 在此基础上提出归一化KLD系数. 解析分析和数值仿真都证明, 多维序列相关结构的变化会引起归一化KLD系数线性的变化. 数值仿真还证明, 即使多维序列中仅有其中的两个时间序列的相关结构发生改变, 归一化KLD系数仍能灵敏地检测到. 不仅如此, 归一化KLD系数还可用于非平稳时间序列的分析. 耦合映象格子的数值仿真结果表明, 归一化KLD系数还能够分析非线性系统的相关结构.     

“闪光二号”加速器HPIB的产生及应用初步结果

主要给出了“闪光二号”加速器高功率离子束(HPIB)产生及应用研究的初步结果.介绍了强箍缩反射离子束二极管的结构及工作原理，给出了考虑阴阳极产生的等离子体运动对二极管间隙影响的饱和顺位流修正公式.实验得到的离子束峰值能量约500keV，峰值电流约160kA.介绍了利用高功率离子束(质子束)轰击¹⁹F靶产生6—7MeV准单能脉冲γ射线的初步实验结果，给出了利用高功率脉冲离子束模拟1keV黑体辐射x射线对材料的热-力学效应初步研究结果. 关键词： 高功率离子束 箍缩二极管 准单能脉冲γ射线 热-力学效应