Oscillatory transverse electric field enhances protein resolution and capacity of size-exclusion chromatography

Protein separations by a novel size-exclusion electrochromatography (SEEC) are presented. The present SEEC, denoted as pSEEC, was established with an oscillatory low-voltage electric field perpendicular to the mobile-phase streamline. Retention experiments with different proteins indicated that the influence of electric field strength on the partition coefficient is different for different proteins as well as for the same protein under different mobile-phase conditions. These results of protein retention led to the experimental design of protein separations with binary mixtures of BSA and immunoglobulin G (IgG), myoglobin (Myo) and lysozyme (Lys), as well as ovalbumin (Oval) and Myo. The separation results for the binary protein systems sufficiently exhibited the applicability of the pSEEC for various separations in terms of their molecular weights (MWs) as well as pIs. For example, it was possible to separate the gel-excluded proteins (BSA/IgG) as well as gel-permeable and similar-molecular-weight proteins (Myo/Lys) by the pSEEC. Moreover, in the cases of Oval/ Myo, which could be partially separated by size-exclusion chromatography, the use of the pSEEC greatly improved the resolution and the separation became possible at high sample loading. The results indicate that the pSEEC technology is promising for preparative protein separations.     

Extended application of a chiral stationary phase based on (+)-(1 8-crown-6)-2,3,11,12-tetracarboxylic acid to the resolution of N-(substituted benzoyl)-alpha-amino acid amides

A chiral stationary phase (CSP 1) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was applied to the resolution of N-(substituted benzoyl)-alpha-amino acid amides and esters. N-(Substituted benzoyl)-alpha-amino acid amides were well resolved using a mixture of acetic acid-triethylamine-acetonitrile (0.01:0.05:100, v/v/v) as an optimum mobile phase while N-(substituted benzoyl)-alpha-amino acid esters were not resolved at all. In contrast, both N-(substituted benzoyl)-alpha-amino acid amides and esters were not resolved at all or resolved very poorly on another CSP (CSP 2), which lacks the two N-H hydrogens of the amide tethers of CSP 1. Among the substituents on the benzoyl group of analytes, the nitro group was the best for good resolution of analytes on CSP 1. From these results, the two N-H hydrogens of the amide tethers of CSP 1, the carbonyl oxygen of the amide group of analytes, and the nitro group on the benzoyl group of analytes were concluded to play significant roles in chiral recognition. In addition, various N-(3,5-dinitrobenzoyl)leucine amides with different lengths of N-alkylamide chains were resolved on CSP 1 and N-(3,5-dinitrobenzoyl) leucine N-propylamide was found to show the best chiral recognition in terms of the separation (alpha = 1.30) and the resolution factor (Rs= 3.17).     

A novel colorimetric sensor of dihydrogen-phosphate based on metal complex between 8-hydroxy quinoline-5-azo-4'-nitrobenzene and cobalt

A novel colorimetric sensor based on 8-hydroxy quinoline-5-azo-4'-nitrobenzene (1) was prepared and used for recognizing anions. 1 and its metal complex (1.Co) were found to show response to anions such as CH(3)CO(2)(-), H(2)PO(4)(-), HSO(4)(-), F(-) and dramatic color changes were observed. The selectivity and sensitivity of 1 and 1.Co for sensing anions were different, which was in the order of CH(3)CO(2)(-)>F(-)>H(2)PO(4)(-)>HSO(4)(-) for 1 and H(2)PO(4)(-)>HSO(4)(-)>CH(3)CO(2)(-) approximately F(-) for 1.Co, respectively. In CH(3)CN, sensor 1.Co exhibited excellent specificity toward H(2)PO(4)(-), and the color variety was dependent on the concentration of H(2)PO(4)(-) which was attributed to anion structure and stability of anionic complex (1-anion), metal complex (1-Co) and inorganic complex (Co-anion).     

1H NMR spectral studies on the polymerization mechanism of indole and its derivatives

The existence of NH bond according to the hydrogen nuclear magnetic resonance ((1)H NMR) spectra of polyindole and its derivatives, such as poly(5-bromoindole), poly(5-cyanoindole), poly(5-nitroindole), poly(5-methylindole), proved polymerization of high-quality polyindoles, which were electrosynthesized from middle strong Lewis acid boron trifluoride diethyl etherate (BFEE) and its mixed electrolytes with additional diethyl ether, occurred at 2,3-position. The elongation of the conjugation length made the chemical shift of all the protons of polyindoles to lower field in comparison with those of monomers.     

Synthesis and luminescence properties of lanthanide complexes with a new aryl amide bifunctional bridging ligand

A new aryl amide type bifunctional bridging ligand 4,4'-bis{[(2'-benzylaminoformyl)phenoxyl]methyl}-1,1'-biphenyl (L) and its complexes with lanthanide ions (Ln=Pr, Eu, Gd, Tb, Ho, Er) were synthesized and characterized by elemental analysis, infrared spectra, conductivity measurements and thermal analysis. At the same time, the luminescence properties of the Eu and Tb complexes in acetone solutions were investigated. Under the excitation of UV light, these two complexes exhibited characteristic emission of europium and terbium ions. And the lowest triplet state energy level T1 of this ligand matches better to the lowest resonance energy level of Tb(III) than to Eu(III) ion.     

Eta1 and eta2 complexes of lambda3-1,2,4,6-thiatriazinyls with CpCr(CO)x

The title heterocyclic radicals coordinate to either 17e CpCr(CO)3 or 15e CpCr(CO)2 moieties as one-electron or as three-electron donors, respectively; in the former the bonding is via the perpendicular p orbital of the sulfur atom, while in the latter bonding is via p(pi) orbitals on both sulfur and nitrogen.     

Ferromagnetism in ZnCoO thin films deposited by PLD

Multilayer structures A–B–A⋅⋅⋅ consisting of alternating layers of a metal A and a semiconductor B can show large anisotropy in their transport properties. In tilted multilayer structures, where layer planes and sample surface include a nonzero tilt angle, nonvanishing off-diagonal elements in the sample’s transport tensors lead to transverse Seebeck and Peltier effects. Achievable temperature differences and figures of merit for transverse Peltier cooling are discussed and compared with experiments, coefficients of performance for transverse power generation are calculated.     

Material ablation and plasma plume expansion study from Fe and graphite targets in Ar gas atmosphere

Study of expansion dynamics of pulsed-laser ablation plasmas from Fe and graphite targets is presented. A 532 nm Q-switched Nd:YAG laser with fluence of 30 J cm⁻² is used to ablate the Fe and graphite targets in various Ar ambient gas pressures. Plasma ablation parameters for the two target materials are estimated using snow-plow and shock-wave models, which show that the laser beam energy deposited to ablated species remains at 70% for both targets at all ambient pressures. The plume splitting was observed, more prominently, for Fe plasma as it moves faster compared to graphite plasma. The difference in plasma plume fronts’ speeds for different targets was attributed to the significant difference in mass of the ablated plasma for two targets, as estimated from simulation results.     

中国北方古建油饰彩画中绿色颜料的光谱分析

古建油饰彩画中颜料成分的分析鉴定是古建维修、保护的重要基础工作。文章利用X射线荧光分析、X射线衍射分析、扫描电镜-能谱分析技术,首次系统地分析检测了来自北京、山西、甘肃等中国北方地区的27个古建油饰彩画中的绿色颜料。结果表明,其中15个样品使用了巴黎绿这种含铜、砷的人工合成颜料,其余样品未检测出矿物颜料,显色成分应为人工合成的有机物。在所有分析样品中未检测到古代常用的绿色颜料石绿和氯铜矿的存在。该研究工作开辟了光谱分析技术应用于古建油饰彩画颜料鉴定的新领域,为该类文物分析鉴定、修复材料的选择提供了科学数据。