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941.
Jinghua Zhang Toshiko Nagahama Hiroki Ohwaki Yasuhiro Ishibashi Yuji Fujita Sunao Yamazaki 《Analytical sciences》2004,20(1):37-43
To understand the cause of discoloration of the sea laver "nori," which is found in the Ariake Sea, the concentrations of pigments and elements in the normal and discolored laver samples were determined. In the discolored samples, a decrease in all of the pigments, chlorophyll a and carotenoids, and proteinous pigments, phycobiliproteins, was clearly observed. This was accompanied by a decrease in the content of Fe, Zn, Mn, Cu, and P. Good correlations between these elements and chlorophyll a, as well as between these elements and phycobiliproteins, were confirmed, indicating that, in addition to the deficiency of nitrogen and phosphorus, the deficiency of trace elements (Fe, Zn, Mn, and Cu), which are specifically required for photosynthesis, could be a reason for the discoloration of nori. The cause of elemental deficiency is also discussed. 相似文献
942.
The binary phase diagram of KNO3-KClO3 is studied by means of differential scanning calorimetry (DSC) and high-temperature X-ray diffraction. The limited solid solutions, K(NO3)1−x(ClO3)x (0<x<0.20) and K(NO3)1−x(ClO3)x (0.90<x<1.0), were formed in the KNO3-based solid solutions and KClO3-based solid solutions phase, respectively. For KNO3-based solid solutions, KNO3 ferroelectric phase can be stable from 423 to 223 K as a result of substituting of NO3 by ClO3-radicals. The temperatures for solidus and liquidus have been determined based on limited solid solutions. Two models, Henrian solution and regular solution theory for KNO3-based (α) phase and KClO3-based (β) phase, respectively, are employed to reproduce solidus and liquidus of the phase diagram. The results are in good agreement with the DSC data. The thermodynamic properties for α and β solid solutions have been derived from an optimization procedure using the experimental data. The calculated phase diagram and optimized thermodynamic parameters are thermodynamically self-consistent. 相似文献
943.
Chao Feng Zhang Li Fan Pin Yang 《中国化学快报》2007,18(1):97-98
Zinc may play a role as a co-factor in the pathogenesis of Alzheimer's disease(AD)through influencing the conformation and neurotoxicity of amyloidβ-protein(Aβ).Using the fluorescamine assay,we show for the first time that Zn~(2 )induced Aβ(10-21) aggregate in a concentration-dependent manner.These results indicate that Aβ(10-21)can be used as an in vitro model in Zn~(2 )- induced Aβaggregation and that the region 10-21 to be the minimal fragment of zinc-binding domain of full length Aβ(1-42). 相似文献
944.
Summary. Phenoxyacetic acid distribution in two-phase systems n-aliphatic hydrocarbon (C5–C8) – water and its dimerization in organic phase were investigated. The values of distribution coefficient (D
HR), distribution constant (K
D), and dimerization constant (K
dim) of acid were obtained. The empirical correlations of these quantities with Hildebrand solubility parameter of organic solvents were established. The influence of pH of the aqueous phase as well as the polarity of the applied organic solvents on phenoxyacetic acid physical chemistry in
the two-phase systems was described. 相似文献
945.
946.
硫酸颜色反应用于荧光法测定利血平研究 总被引:6,自引:1,他引:6
提出了硫酸颜色反应用于利血平的荧光分析新方法。利用血平与浓硫酸反应,生成强荧光物质,所得产物的荧光强度与利血平的浓度在0-0.6μg/mL范围内有良好的线性关系。检测限为0.2ng/mL。本法可直接用于尿液中利血平的定量分析,回收率为82.5%-84.2%。 相似文献
947.
Mao-fengZhang Qiao-hongYao Chun-huiHuang Wei-xiaoCao 《高分子科学》2005,(1):27-27
A kind of azo-containing resin (Azo-R) was synthesized by a simple way through the coupling reaction of 2-nitro-N-methyldiphenylamine-4-diazoresin (NDR) with phenol, and a new covalentely attached multilayer film from Azo-R as H-donor and photosensitive diazoresin, diphenylamine-4-diazoresin (DR) as H-acceptor via H-bonding attraction by selfassembly technique has been fabricated. Following the decomposition of diazonium group of DR under exposure to UV light, the H-bonds between the layers of the film convert to covalent bonds and the film becomes very stable toward polar solvents or electrolyte aqueous solutions. Thus the UV-irradiated azo-containing films can be used to measure photocurrent in a conventional three-electrode photoelectrochemical cell using KCl as supporting electrolyte. It was confirmed that the azo-containing multilayer film is responsible for the photocurrent generation. 相似文献
948.
Helseth LE Muruganathan R Zhang Y Fischer TM 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7271-7275
We investigate the self-assembly of colloidal particles on microscopic decane droplets in water and show that, by use of paramagnetic colloids, it is possible to assemble ringlike structures that can be controlled with a magnetic field. Moreover, the use of paramagnetic colloids allows us to determine the attractive forces between the colloids located at the three-phase contact line between decane, water, and air. The attractive force is in the femtonewton range and is attributed to capillary interactions due to interface deformations. When the liquid emulsion dries on a glass slide, we observe solid deposits in the form of microscopic rings of varying diameters. 相似文献
949.
Menger FM Zhang H Caran KL Seredyuk VA Apkarian RP 《Journal of the American Chemical Society》2002,124(7):1140-1141
A gemini surfactant is able to promote columnar jointing in vitreous ice where long pillars, often of hexagonal cross section, are formed. This jointing is visible by cryo-high-resolution scanning electron microscopy (cryo-HRSEM), in which colloidal suspensions in bulk water are cooled rapidly in liquid ethane, thereby avoiding the potential artifacts with other types of EM. The jointing is proposed to arise from a new type of colloidal morphology where the surfactant self-assembles into hexagonal columns. Evidence for this mechanism comes from a cryo-HRSEM photo of an ice-free hexagonal "skeleton" composed of surfactant. Cryo-HRSEM, a method that is just beginning to realize its potential, would seem to have a promising future in the discovery of additional and as yet unimagined colloidal structures. 相似文献
950.
The formation and unimolecular reactions of primary ozonides and carbonyl oxides arising from the O(3)-initiated reactions of isoprene have been investigated using density functional theory and ab initio molecular orbital calculations. The activation energies of O(3) cycloaddition to the two double bonds of isoprene are found to be comparable (3.3-3.4 kcal mol(-1)), implying that the initial two O(3) addition pathways are nearly equally accessible. The reaction energies of O(3) addition to isoprene are between -47 and -48 kcal mol(-1). Cleavage of primary ozonides to form carbonyl oxides occurs with a barrier of 11-16 kcal mol(-1) above the ground state of the primary ozonide, and the decomposition energies range from -5 to -13 kcal mol(-1). OH formation is shown to occur primarily via decomposition of the carbonyl oxides with the syn-positioned methyl (alkyl) group, which is more favorable than isomerization to form dioxirane (by 1.1-3.3 kcal mol(-1)). Using the transition-state theory and master equation formalism, we determine an OH yield of 0.25 from prompt and thermal decomposition of the carbonyl oxides. 相似文献