Micellar extraction preconcentration of silver with thiazolylazo reagents into a nonionic surfactant phase at the cloud point

The effect of the main factors on the extraction of the silver complexes of 4-(2-thiazolylazo)resorcinol and 1-(2-thiazolylazo)-2-naphthol into a micellar phase of a nonionic surfactant at the cloud point was studied. Conditions were found for the atomic absorption determination of silver with micellar extraction preconcentration into an OP-7 phase upon heating.     

CM⁃Phos配体在钯催化交叉偶联反应中的应用

本文综合评述了近年来2-[2-(二环己膦基)苯基]-1-甲基-1H-吲哚(CM-Phos)膦配体及其衍生物在钯催化的交叉偶联反应中的应用, 主要根据不同种类的交叉偶联反应进行系统性分述, 并对该领域的发展前景进行了展望.     

一种蓝光发射星型有机分子的合成及光电性质

采用分子设计的思想,通过多步反应合成了一种新型的以N原子为中心的蓝光发射星型有机小分子。用1H NMR,MS和元素分析进行了表征,研究了化合物的热稳定性和真空镀膜膜层的光致发光性质,用循环伏安法测定了其电化学性能。结果表明,这种合成的有机化合物光致发光性能优良(量子效率达到87%),热稳定性好,可作为制作有机电致发光器件的候选材料。     

“绿色”液体激光介质的非线性光学特性研究

 利用氧化钕和盐酸为原料制得Nd(phen)2Cl3(三氯二邻菲罗啉合钕),测得其光谱特性并以稀土氧化钕、苯甲酸和邻菲罗啉为原料制得绿色液体激光介质钕离子的配合物——NdB3phen（三苯甲酸—邻菲罗啉合钕）.利用飞秒激光器,采用单光束Z-扫描法研究了NdB3phen的三阶非线性光学特性.结果表明:当入射飞秒激光脉冲波长为400 nm,峰值功率密度为2.94×1014 W/m2,脉宽为117 fs时,测得样品NdB3phen的非线性折射率为－2.84×10－18 cm2/W|NdB3phen在开孔条件下呈现反饱和吸收现象,测出双光子吸收系数的值为9.11×10－12 m/W.实验结果表明,NdB3phen的双光子吸收系数和非线性折射率随着光强的增强而增大.     

Flame atomic absorption determination of manganese(II) in natural water after cloud point extraction

The possibility to use 4-(2-pyridylazo)resorcinol (PAR) and 1-(2-pyridylazo)-2-naphthol (PAN) for manganese(II) concentrating by the micellar extraction at cloud point (CP) temperature and subsequent atomic absorption spectrometry (AAS) determination was investigated. Under the optimum conditions, preconcentration of 100 ml of water sample in the presence of 1% non-ionic surfactant (NS) OP-7, 1×10⁻⁴ M 1-(2-pyridylazo)-2-naphthol permitted the detection 5 μg l⁻¹ manganese. The proposed method has been applied to the AAS determination of manganese in water samples after cloud point extraction.     

Generalised twists, , and the p-energy over a space of measure preserving maps

Let be a bounded Lipschitz domain and consider the energy functional

with p]1,∞[ over the space of measure preserving maps

In this paper we introduce a class of maps referred to as generalised twists and examine them in connection with the Euler–Lagrange equations associated with over . The main result is a surprising discrepancy between even and odd dimensions. Here we show that in even dimensions the latter system of equations admit infinitely many smooth solutions, modulo isometries, amongst such maps. In odd dimensions this number reduces to one. The result relies on a careful analysis of the full versus the restricted Euler–Lagrange equations where a key ingredient is a necessary and sufficient condition for an associated vector field to be a gradient.     

Lyophilic properties of surfactant-rich phases of polyethoxylated alkylphenols formed at cloud point temperature

The influence of the concentration conditions, solutions acidity, and electrolyte additions on the lyophilic properties of the surfactant-rich phases of polyethoxylated alkylphenols OP-7 and OP-10 formed at cloud point temperature were studied. The lyophilic properties of surfactant-rich phases were determined by estimating of their effective hydration values and solvation free energy of methylene and carboxyl groups at cloud point extraction of aliphatic monocarboxylic acids. It was shown that the surfactant-rich phases formed from the dilute surfactant solutions have more hydrophobic properties than the phases formed from the high concentrated solutions. The possibility of changing the lyophilic properties of surfactant-rich phases by electrolyte additions was shown: complex formation between electrolyte cation and the polyoxyethylene chain of the surfactant increases the hydrophilic properties of the surfactant-rich phases. Calculations of the solvation free energy of methylene and carboxylic fragments of the aliphatic carboxylic acids at micellar extraction showed the uniqueness of the surfactant-rich phases which are able to energetically advantageously extract both hydrophilic and hydrophobic molecules of substrates.     

Using FTIR spectroscopy to detect sericin on historic silk

Silks represent some of the most precious ancient and historic textile artefacts in collections worldwide.Their optimum preservation demands an appreciation of their characteristics.One important concern,especially with regard to ancient Chinese silks,is whether the fabrics have been degummed.Silks with remnant sericin gum coating the fibroin fibres would require different conservation protocol.In previous research on aged silks,the presence of sericin has been inferred from amino acid analysis of hydrolysa...     

含钒(IV)和钒(V)的钨锗混合价杂多酸盐的合成及其结构表征

报道了含钒(IV)和钒(V)的钨锗混合价杂多酸盐的合成、电子吸收光谱及单电子还原态的ESR谱。α-和β-[HGeV^I^VV2^VW9O40]^7^-的溶液ESR谱是由40余条超精细线组成的, 表明在阴离子中3个VO6八面体是角顶共用, 且其中一个桥氧原子是质子化的。     

The invariants of the non-degenerate representations of the group of the pseudo-orthogonal matrices SO (p, 1)

The invariants of the non-degenerate representations of the group of pseudo-orthogonal matrices SO(p, 1) are constructed.