沉淀溶解法制备纳米硫化锌

以烷基黄原酸锌和硫化钠分别为锌源和硫源，采用烷基黄原酸锌沉淀溶解法制备了粒度可调、粒径分布比较窄的面心硫化锌纳米粒子，利用比表面积(BET)测定、透射电镜(TEM)、粉末X射线衍射(XRD)、傅里叶转换红外光谱(FTIR)等方法对合成的硫化锌纳米粒子进行了表征。结果表明随着烷基黄原酸锌链长的增长，通过添加硫化钠而生成的硫化锌纳米粒子的粒径逐渐减小。本文还对沉淀溶解法制备纳米硫化锌的溶液化学反应机理进行了探讨。     

Rapid determination of panaxynol in a traditional Chinese medicine of Saposhnikovia divaricata by pressurized hot water extraction followed by liquid-phase microextraction and gas chromatography-mass spectrometry

Panaxynol is a bioactive component in traditional Chinese medicines (TCMs), such as Saposhnikovia divaricata and Panax ginseng. In the work, two solvent-free sample techniques of pressurized hot water extraction (PHWE) and headspace liquid-phase microextraction (HS-LPME) were combined and developed for the determination of panaxynol in a TCM of S. divaricata. Panaxynol in the TCM samples from different growing areas was extracted by PHWE in dynamic mode, followed by extraction and concentration with HS-LPME and analysis with gas chromatography-mass spectrometry (GC-MS). The PHWE and HS-LPME parameters were optimized and the method validations were studied. Panaxynol in S. divaricata from four different growing areas was quantitatively analyzed by internal standard method. These results have shown that PHWE-LPME-GC-MS is a simple, rapid, efficient and low-cost method for the determination of panaxynol in TCMs and is a potential tool for TCM quality assessment.     

Implementation of the finite field perturbation method in the CRYSTAL program for calculating the dielectric constant of periodic systems

The finite field approach has been implemented in the periodic ab initio CRYSTAL program and been used for calculating the dielectric constants of crystalline LiF and MgO (FCC structure) and BeO (wurtzite structure). To maintain the periodicity along the applied field direction, a "sawtooth" potential is used in conjunction with a supercell scheme. Supercells four to five times longer than the primitive cell in the direction of the applied field provide well-converged results. The influence of the computational parameters is discussed. An alternative scheme has also been implemented, for inner check, that consists of applying a static electric field to a slab of increasing thickness in the direction orthogonal to the surface; the dielectric response at the center of the slab is shown to converge rapidly to the bulk value evaluated with the sawtooth field. The method is accurate and permits the determination of nonlinear corrections to the dielectric constant. When used in conjunction with the local density approximation (LDA) scheme, it provides for the dielectric constant of the three above-mentioned compounds values close to those recently obtained with a time-dependent density functional theory approach.     

Modification of polybenzimidazole: Synthesis and thermal stability of poly(N1-methylbenzimidazole) and poly(N1,N3-dimethylbenzimidazolium) salt

Poly(N₁,N₃-dimethylbenzimidazolium) (PDMBI) salt and poly(N₁-methylbenzimidazole) (PMMBI) were synthesized by methylation of commercial polybenzimidazole [poly-2,2′-(m-phenylene)-5,5′-bibenzimidazole (PBI)]. First, the N-lithium salt of polybenzimidazole was formed by treating polybenzimidazole solution of 1-methyl-2-pyrolidinone (NMP) with lithium hydride at 80°C for 18 h. Ninety percent substitution of PMMBI was obtained by treating the N-lithium salt of PBI with equimolar ratio of iodomethane at room temperature. Upon addition of excess iodomethane to the lithium salt of PBI at 80°C, a polymer was formed that showed 100% substitution on the N₁ nitrogen and about 30% substitution of the methyl group on the N₃ nitrogen in the form of N₁,N₃-dimethylbenzimidazolium iodide salt [PDMBI (30%)]. The content of the benzimidazolium iodide salt was increased to about 90% by dissolving PDMBI (30%) in dimethyl sulfoxide (DMSO) and re-treating with excess iodomethane at 80°C overnight. The modified PBI polymers were characterized by NMR and FTIR. The modified PBI differed in solubility from PBI. PMMBI could be easily dissolved in NMP and PDMBI in DMSO at room temperature. The solution of PDMBI could be mixed with water in all proportions without precipitation. PDMBI could be also dissolved directly in a mixture of DMSO and water (1 : 1). Typical polyelectrolyte behavior of viscosity was found in solution of PDMBI (30%) and PDMBI (90%) when DMSO and a mixture of DMSO and water were used as solvents. A salt effect on viscosity was also found in the mixed solvent solution. Thermogravimetric analysis (TGA) showed that the methyl group on the imidazole ring was unstable above 180°C under nitrogen. When PDMBI was heated under nitrogen, one of the methyl groups was lost with the counterion to result in a neutral PMMBI. © 1993 John Wiley & Sons, Inc.     

数据校正法与条件滴定度法提高络合滴定准确度

对于1gK＇_(My)C_M或1gK＇_(MY)C_M -1gK＇_(NY)C_N较小的络合滴定,可以使用单一参比溶液,使全部试样的pMeq均大于或小于该参比溶液的PM值,并使用数据校正法或条件滴定度法校正结果。实验证明,即使1gK＇_(MY)C_M或1gK＇_(MY)C_M -1gK＇_(NY)C_N小至4,仍能得精确结果。     

The ab initio neglect of differential diatomic overlap method

The ab initio Neglect of Differential Diatomic Overlap (N.D.D.O.) method of Roby is tested numerically for an extensive series of molecules. Agreement with the full ab initio molecular orbital method is poor. Total energies are more negative and dipole moments are overestimated. The failings of the N.D.D.O. method are accounted for using multipole-multipole expansions.     

茶碱抗体的制备及鉴定

茶碱在临床上是一种非常有用的药剂。本文报道一种新的茶碱抗血清的制各及鉴定方法．用混合酸酐法合成抗原，借助于紫外光谱对其进行定性和定量分析。用混合免疫法免疫兔子，用免疫扩散法对抗血清进行鉴定。     

Comparison between the adsorption behaviors of an organic cation and an organic anion on several reversed-phase liquid chromatography adsorbents

Adsorption data of an organic cation (propranololium chloride) and an organic anion (sodium 1-naphthalene sulfonate) were measured by frontal analysis on two RPLC adsorbents, Symmetry-C18 and XTerra-C18, with aqueous solutions of methanol as the mobile phases. The influence of supporting neutral salts on the adsorption behavior of these two ions are compared. The Henry constants are close (H approximately 5). The four sets of isotherm data are all well accounted for using the bi-Moreau model. However, the isotherms of the two ions behave differently at high concentrations. The initial behaviors of all the isotherms are antilangmuirian but remain so in a much wider concentration range for the cation than for the anion, due to its stronger adsorbate-adsorbate interactions on the low-energy adsorption sites. The retention times of both ions increase with increasing concentration of neutral salt in the mobile phase, suggesting the formation of ion-pair complexes, with Cl- for the cation and with Na+ for the anion. The adsorbate-adsorbate interactions vanish in the presence of salt and the bi-Moreau isotherm model tends toward a bi-Langmuir model. Differences in adsorption behavior are also observed between the cation and the anion when bivalent inorganic anions and cations, respectively, are dissolved in the mobile phase. High concentration band profiles of 1-naphthalene sulfonic acid are langmuirian, except in the presence of a trivalent cation, while those of propranolol are antilangmuirian under certain conditions even with uni- or divalent cations.     

Water soluble cyclodextrin polymers: Their interaction with drugs

The complex forming ability of a water-soluble -cyclodextrin epichlorohydrin, polymer (CDPS) and its different molecular weight fractions was studied and compared with the complexing properties of -cyclodextrin (CD) and dimethyl-CD (DM-CD). CDPS was separated into two main fractions. CDPS and its fractions formed well soluble inclusion compounds with the studied drugs. The low molecular weight fraction formed rather stable complexes with small guest molecules, the high molecular weight fraction was found to be more efficient in binding larger substrates. Structural studies of furosemide-CD complexes were attempted by NMR spectroscopy.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986.     

稀土金属硼氢化物的研究(Ⅸ)——N,N''''-双(邻羟基苯叉)-1,3-丙二胺合稀土(Ⅲ)十氢十硼酸盐的合成

我们曾报道过含闭式氢硼駿根的二齿配体的稀土螯合物的合成及性质。为了解不同配体的稀土配合物在结构及性质上的差异,又合成了四齿(ONNO)配体N,N′-双(邻羟基苯叉)-1,3-丙二胺(salpr),并通过两种方法(模板合成法及配体合成法)合成了稀土配合物的闭式十氢十硼酸盐。化合物均为黄色粉末固体,室温下它们对光、空气、潮汽均稳定。