Monitoring formation of poly(neutral red) film by EQCM

An electrochemical quartz crystal microbalance (EQCM) is employed for monitoring the growth of poly(neutral red) films on platinum in the electrolytic solution containing 5.0 mmol dm⁻³ neutral red, 0.3 mol dm⁻³ H₂SO₄, and 0.5 mol dm⁻³ Na₂SO₄. The in situ measurement of the frequency changes of the EQCM reveals that both the adsorption/desorption of neutral red and the formation of poly(neutral red) film can be observed together with anion sorption/desorption during the redox transformation of the polymer, and that the polymerization rate of neutral red increases slowly before the 11th cycle and then increases quickly with increasing number of potential cycles. Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 3, pp. 284–289. The text was submitted by the authors in English.     

Melamine cyanurate-microencapsulated red phosphorus flame retardant unreinforced and glass fiber reinforced polyamide 66

A novel microencapsulated red phosphorus (RP) was prepared through the molecular self-assembly of melamine cyanurate (MCA). Compared with the conventional encapsulated RP, MCA-encapsulated RP (MERP) shows simpler and more environment-friendly preparation process higher thermal stability and lower moisture absorption. With MERP filled in unreinforced polyamide 66 (PA66) and glass fiber (GF) reinforced PA66, flame retardant materials with satisfactory flame retardancy and mechanical performance can be obtained. The influence of the MCA/RP ratio on the flame retardancy as well as the condensed phase of MERP flame retardant PA66 was investigated to reveal the nitrogen-phosphorus (N-P) synergistic flame retarding effects between MCA and RP.     

Differential pulse cathodic stripping adsorption voltammetric determination of trace amounts of lead using factorial design for optimization

A sensitive cathodic stripping voltammetric method is developed for determination of lead(II), with adsorptive collection of complexes with Pyrogallol red (PGR) on to a hanging mercury drop electrode. After accumulation of the complex at −0.80 V vs. Ag/AgCl reference electrode, the potential is scanned in a negative direction from −0.20 to −0.50 V with differential pulse method. Then the reduction peak current for the lead(II)-PGR complex is measured at −0.39 V. The influence of reagent and instrumental variables was completely studied by factorial design analysis. The optimum analytical conditions for the determination of lead(II) were established. Under optimum conditions, lead(II) determined in the range of 0.1-30.0 ng ml⁻¹ with a limit of detection of 0.06 ng ml⁻¹. The method is successfully applied to determination of lead(II) in water sample.     

有机小分子染料和聚阳离子分子超薄膜的制备及其摩擦学性能研究

制备了以有机小分子染料酸性红 1 8为阴离子、以聚烯丙基氯化铵和聚乙烯亚胺为聚阳离子的分子沉积膜 ,用紫外可见分光光度计、接触角测定仪和椭圆偏振光测厚仪对所制备的超薄膜进行了表征 .用DF PM型动 静摩擦系数精密测定装置考察了超薄膜的摩擦学性能 ,采用扫描电子显微镜对薄膜的磨痕表面进行了观察 .结果表明 ,所制备的超薄复合沉积膜具有良好的减摩和耐磨性能     

Covalent Structures of Phosphorus: A Comprehensive Theoretical Study

Starting from earlier work by Baudler we introduce a chemical heuristic for the systematic deduction and classification of covalent partial structures of phosphorus in polycyclic phosphanes, phosphorus-rich polycyclic phosphides, and allotropes of phosphorus except the black forms. This approach is used to direct ab initio techniques (which also confirm the rules) in the quest for as yet unknown forms of molecular or macromolecular phosphorus. Based on calculated stabilities of systematically generated structural alternatives we rationalize the stabilities of Hittorf's phosphorus and of molecular P₄, confirm the possible existence of at least one other crystalline allotropic form of phosphorus, and provide insight into the probable structure of amorphous red phosphorus. In total, the combined approach of chemical heuristics and large scale ab initio calculations presented in this work supplies a coherent chemical understanding of covalent polyphosphorus structures.     

Structural Characteristics of Xyloglucan – Congo Red Aggregates as Observed by Small Angle X-ray Scattering

Xyloglucan is a type of hemicellulose with a cellulose backbone containing (1→6)-α-xylose or (1→2)-β-galactoxylose as a side chain. It is soluble in water. Its aqueous solution forms a gel or gel-like precipitate by addition of Congo red. Xyloglucan gel structures with various concentrations of Congo red were observed by small angle X-ray scattering (SAXS) at the nano-level. SAXS results indicated that the xyloglucan chains interacted with Congo red, and that an increase of concentration of Congo red induced a characteristic cross-linking domain, which consisted of a flat structure containing stacked xyloglucan chain assemblies. The Congo red molecules are inserted between the xyloglucan chains.     

芦荟中多糖的光度测定新方法

利用正交试验考察了芦荟多糖与刚果红显色反应的最佳条件；研究了麦芽糖糊精等多糖、蔗糖等低聚糖和葡萄糖等单糖对显色反应的影响；建立了简便快速、常见糖类基本无干扰的测定芦荟多糖含量的吸光光度法。对芦荟鲜叶和芦荟制品中的多糖进行分析，加标回收率在92％～96％范围内，相对标准偏差≤5％。     

Fluoride-induced chemiluminescent decomposition of dioxetanes bearing a siloxyaryl moiety to produce an alkyl aryl ketone as an emitter

Tetrabutylammonium fluoride induces the decomposition of 1-tert-butyl-4,4-dimethyl-5-(3-siloxyphenyl)-2,6,7-trioxabicyclo[3.2.0]heptane (4a) in DMSO to form an oxyanion of aromatic ketone (14a) as an emitter with high singlet-chemiexcitation yield comparable with that for a chemically initiated electron exchange luminescence (CIEEL) active dioxetane producing an oxyanion of aromatic ester as an emitter. A 7-siloxynaphthalen-2-yl analog (4b) was found on similar treatment to emit light with the maximum wavelength the longest among CIEEL-active dioxetanes hitherto known.     

Sr／Ca比变化对红色荧光粉Ca1-xSrxS：Eu^2＋的影响

在CO气氛下采用固相反应法合成了发红光的Ca1-xSrxS:Eu^2 荧光粉，研究了基质阳离子Sr／Ca比变化对其晶体性质及发光性能的影响。结果表明，随着Sr／Ca比的减少，荧光粉的晶胞参数逐渐降低；同时，由于受电子云膨胀效应和晶体场影响，发射主峰向长波方向移动，红色比逐渐增大，色纯度提高。     

Citrate selectivity of poly(neutral red) electropolymerized films

The synthesis and the spectroscopic and potentiometric characterization of electropolymerized films obtained from neutral red (NR) on Pt surface are described. FT Raman and NMR spectroscopy were used for evaluation of the resulting poly(NR) layers. Then potentiometry was applied to study the characteristics of the complexation of carboxylates with the poly(NR) films. A potentiometric poly(NR) sensor showing high selectivity for citrate anion was employed for its determination in soft drinks.