Ab initio Valence Bond Study on AB-type Molecules,A Description for XH(X=L,Be,B,C,N,O,F) and XF(X=Li,Be,B)

Ab initio valence bond method is employed to quantitatively study the concepts of ionic resonance energy and ionicity of a chemical bond in the cases of hydrides XH(X=Li,Be,B,C,N,O,F) and fluorides XF(X=Li,Be,B),By establishing the relationship between resonance and stability,and comparing the calculated ionicities with Pauling‘s earlier estimations in the above diatomic molecules,the merits of Pauling‘s classical resonance theory were demonstrated at the ab initio level.     

Synthesis and analytical application of tribromocarboxyarsenazo as a new chromogenic reagent for zirconium

A new chromogenic reagent tribromocarboxyarsenazo has been synthesized and the chromogenic reaction of this reagent with zirconium studied. In the medium of 0.5 mol/1 HCl, a blue complex is formed by the reaction of zirconium with tribromocarboxyarsenazo. The maximum absorption of the complex is at 633 nm, and the apparent molar absorptivity is 4.8 x 10(4) 1/mol/cm. Beer's law is obeyed over the zirconium concentration range 0-18, mug/25 ml. The method has been applied to the determination of zirconium in aluminum, copper and magnesium alloys with satisfactory results.     

Multinuclear NMR study of lanthanide(III) complexes of 1,2-PDTA in aqueous solution

The complexation of lanthanide(III) cations with 1,2-propanediaminetetraacetate (1,2-PDTA) in aqueous solution has been investigated by ¹⁰Na, ³⁵Cl, ²H and ¹¹O NMR shift measurements. It has been shown that the contact shifts are dominant for ¹⁷O, ¹⁶Cl and ²H (only for the heavier lanthanide series) and the pseudocontact shifts are dominant for ²⁵Na. It is suggested that the 1,2-PDTA ligand is bound pentadentately via the two nitrogens and the three carboxylates for the lighter lanthanide complexes, hexdentately via the two nitrogens and the four carboxylates for the heavier ones. The numbers of the water coordinated were determined. The small amount of chloride anion in inner coordination sphere was observed.     

Correct identification of polychlorinated biphenyls in temperature-programmed GC with ECD detection

A method has been developed for peak identification of PCBs in GC with ECD detection under different temperature programs and isothermal conditions on two commonly used columns (DB-5 and DB-1701). This was achieved by means of accurate calibration of retention times based on the concept of the relative retention index P (i) and retention times of the selected PCB internal standards. The P (i) was calculated from the predicted retention times with the database of the retention parameters (A, B) and the migration equations. Through comparison of the calibrated and experimental retention times of PCBs in technical samples, it was shown that the developed method was effective for correct PCB comprehensive, quantitative, congener-specific (CQCS) analyses.     

荧光法研究Ge—132对苯丙氨酸Maillard反应的抑制作用

哺乳动物体内氨基酸及蛋白质的非酶糖化反应（Ｍａｉｌａｒｄ反应）与糖尿病及其并发症的关系已引起广泛关注［１］，β－羧乙基锗倍半氧化物（Ｇｅ－１３２）具有预防糖尿病和调节糖代谢的作用［２］，研究Ｇｅ－１３２对Ｍａｉｌａｒｄ反应的抑制作用对于开发防治糖尿病...     

锂辉石—石灰石烧结中煤粉代替重油作燃料的研究和实践

目前世界锂工业原料以锂辉石为主。我国锂辉石储量居世界首位，主要分布于新疆、四川、湖南等地，其中又以四川的储量占全国第一。锂的主要基础化合物ＬｉＯＨＨ２Ｏ系用锂辉石－石灰石烧结法而得，烧结燃料是影响ＬｉＯＨＨ２Ｏ产品价格的重要因素之一。过去国内外均采用...     

构建网络学习资源提高民族高校有机化学课程教学质量

High-quality online course materials were reconstructed through feedback from undergraduate students and online data analysis regarding constructed learning materials on the Chao Xing Learning Platform. They were used for studying organic chemistry courses online and offline in university for nationalities. This model, based on student-centered teaching, can effectively transform students from passively accepting knowledge to actively learning and internalizing knowledge. This strategy can also enhance the students' learning initiative and the effects of learning, and hopefully be helpful to the universities in multi-ethnic areas in developing fundamental disciplined construction of organic chemistry and other courses.     

Chromatographic Features and Molecular Recognition Mechanism of a Strychnine Monolithic Molecularly Imprinted Polymer

A monolithic molecularly imprinted polymer (mMIP) with specific recognition ability for strychnine was prepared by in-situ polymerization, using methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linking agent, toluene and dodecanol as porogenic solvents and 2, 2’-azobisisobutyronitrile (AIBN) as a initiator. Scanning electron microscopy and mercury intrusion porosimetry were used to identify the structural features of the mMIP. The results show that there were three kinds of pore structures. The large through-pore structure allows mobile phase to flow through a column of mMIP with a low back pressure and the other pores lead to the molecular recognition. Some chromatographic conditions such as the pH and the composition of the mobile phase were characterized. Strychnine was separated from compounds such as indole, quinine and brucine. The possible recognition mechanisms were ionic and hydrogen bonding interactions between the strychnine molecule and the mMIP.     

Weighted two-band target entropy minimization for the reconstruction of pure component mass spectra: Simulation studies and the application to real systems

A method is proposed, on the basis of a recently developed algorithm--Band Target Entropy Minimization (BTEM)--to reconstruct mass spectra of pure components from mixture spectra. This method is particular useful in dealing with spectral data with discrete features (like mass spectra). Compared to the original BTEM, which has been applied to differentiable spectroscopies such as Fourier-transfer infrared spectroscopy (FTIR), ultraviolet (UV), Raman, and nuclear magnetic resonance (NMR), the latest modifications were obtained through: (1) Reformulating the objective function using the peak heights instead of their derivatives; (2) weighting the abstract vector VT to reduce the effect of noise; (3) using a two-peak targeting strategy (tBTEM) to deal with strongly overlapping peaks; and (4) using exhaustive search to locate all the component spectra. A set of 50 multi-component mass spectra was generated from ten reference experimental pure component spectra. Many of the compounds chosen have common MS fragments and therefore, many of the pure component spectra have considerable intensity in same data channels. In addition, a set of MS spectra from a real system with four components was used to examine the newly developed algorithm. Successful reconstruction of the ten component spectra of the simulated system and the four component spectra of the real system was rapidly achieved using the new tBTEM algorithm. The advantages of the new algorithm and its implication for rapid system identification of unknown mixtures are readily apparent.     

微波溶样肉桂基荧光酮和表面活性剂连续荧光测定葡萄酒中铁和钴

观察到肉桂基荧光酮(略作CF)在pH≈8与Fc(Ⅲ)配位后荧光增强,CPB的加入使荧光更强,络合物与试剂荧光强度之比F_(FeR)/F_R随0～0.01μg/ml Fe(Ⅲ)线性变化,λ_(ex)=410nm,λ_(ex)=480nm;而CF在pH≈10与Co(Ⅲ)配位后荧光却减弱,乳化剂OP存在时使试剂荧光增强,若以荧光熄灭Co(Ⅲ)灵敏度便提高,试剂与络合物荧光强度之比F_R/F_(CoR)对0～0.016 μg/ml Co(Ⅲ)呈直线关系,λ_(ex)=300nm,L_(em)=352nm。控制化学条件和激发、发射波长,可不经分离测定葡萄酒(微波溶样)中铁和钴。