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991.
A highly sensitive and selective procedure for spectrophotometric determination of silver has been developed. At pH 9.2, in the presence of Triton X-100, silver forms a dark red-violet complex with cadion 2B which has an absorption maximum at 565 nm. The molar absorptivity is 1.0 x 10(5) l.mole(-1).cm(-1). Beer's law is obeyed for silver in the range 0.02-0.8 mug ml . The colour reaction, if EDTA is used as a masking agent, is free from interference by the 20 cations and 19 anions investigated. Only Cl(-), Br(-), I(-), S(2-) and CN(-) interfere and must be absent. This method has been used to determine silver in waste-water. 相似文献
992.
Conditions are described for the preparation of the dihydro (2 and 6) and tetrahydro derivatives (3, 5 and 7) of 18-hydroxy-11-deoxycortisterone (1a) by microbial transformations using Clostridium parapurificum and chemical methods. The products were fully characterized and degraded into their respective 20 → 18 etiolactones. Microbial and chemical reductions of the Δ4-3-ketolactone 8 are presented. 相似文献
993.
Summary The surface dyeability of the poly(vinyl alcohol) fiber with different degree of formalization was studied by measuring -potential of the fiber in alkaline aqueous solutions (pH 10) of a cationic dye Methylene Blue. With the increase in the dye concentration, the sign of the -potential of the fiber changed from negative to positive and thereafter the positive value approximated to saturated value, and the amount of dye adsorbed (expressed in mol/cm2-fiber) increased also. These results may possibly be attributed to the formation of the electrostatic bond between the fiber and the dye. The linear relations were found between and logC
d
and its slope did not change with rise of temperature. The free energy of dyeing G (negative) calculated from the slope of the -logC
id
curve, etc. increased with increasing the degree of formalization of the fiber. This fact corresponds to the increase in the surface dye adsorption with increasing the degree of formalization. With increasing the degree of formalization, the heat of dyeing H (negative) increased and the entropy of dyeing S (positive) decreased. The positive value of S for each fiber, suggests the formation of hydrophobic bond as a driving force to the dyeing of Methylene blue on the fiber surface in addition to the electrostatic bond.This paper is Part XXVII in a series on Studies on -potentials and Surface Dyeability of Natural and Synthetic Fibers in Dye Solution. Part XXVI: T. Suzawa andK. Kawakami, Nippon Kagaku Kaishi1975, No. 7,1134. 相似文献
994.
Bis(methyl)disulphide and the organometallic compound {(Cp)Mo(CO)3}2 in low oxidation state under photolysis give especially with the hexa-fluorobut-2 yne a 18-electron olefin complexe {(Cp)Mo(CO)3(CF3C2CF3SCH3)}. The new compounds are reported and the reaction discussed. 相似文献
995.
Niklowitz PG Li ZY Jardine AP Luo MF Allison W 《The Journal of chemical physics》2004,120(21):10225-10230
The interaction of oxygen molecules with a fullerene surface has been studied using high resolution electron energy loss spectroscopy and temperature programmed desorption. Vibrational excitation of the adsorbed oxygen is observed at 190 meV, an energy value comparable with that for molecular oxygen in the gas phase. We take this to indicate physisorption of molecular oxygen on the C(60) surface. Thermal desorption results also show that the bonding of oxygen molecules to the C(60) overlayer is comparable to that on a graphite surface. A detailed study of the energy dependence of the vibrational excitation reveals an inelastic electron resonance scattering process. The angular dependence of the resonant vibrational excitation exhibits features distinctively different from those for molecular oxygen physisorbed on the related graphite surface, at a comparable coverage. One possible reason is that the corrugated surface potential, due to the curvature of the C(60) molecules, promotes the preferential ordering of the physisorbed oxygen molecules perpendicular to the surface plane of the C(60) overlayer. 相似文献
996.
S. C. Chae Y. N. Jang I. K. Bae K. W. Ryu T. S. Yudintseva S. V. Yudintsev 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):73-77
This study was aimed at the synthesis, study of phase relations and characterization of the garnet ([Ca1.5GdCe0.5]VIII[ZrFe]VI[Fe
x
Al3−x
]IVO12, x = 0−2) intended as promising matrix for actinides (Pu) immobilization. The optimum temperatures of the fabrication of the
garnets ceramics are 1400 °C at x = 2 and 1500 °C at x = 0−1. The garnets lattice parameters and the content of Ce, as an imitator of Pu, increased with the content of iron. It
was suggested that the ability of the garnet for incorporation of Pu was closely related to the ionic radii of the elements
occupied the four-and six-coordinated sites of the structure. 相似文献
997.
A sensitive technique for the determination of trace Cu(II) in various samples after column preconcentration by adsorbing
onto pulverized Amberlite XAD-4 loaded with N-benzoylphenylhydroxylamine (BPHA) was developed. Several experimental conditions,
such as the size of XAD-4, adsorption flow rate, pH of sample solution, and so forth, were optimized. The interfering effects
of diverse concomitant ions were investigated. Al(III), Fe(III), Ni(II), and Co(II) interfered, but the interference by these
ions was completely eliminated by adjusting the amount of XAD-4-BPHA resin to 0.30 g. The dynamic range, the correlation coefficient
(R2), and the detection limit obtained by the proposed technique were 1.0–60, 0.9953, and 0.83 ng/mL, respectively. For validating
the technique, the aqueous samples (stream water, reservoir water, and wastewater), the diluted brass sample, and the plastic
sample were used as real samples. Recovery yields of 94–102% were obtained. These measured data were not different from ICP-MS
data at the 95% confidence level. This method was also validated by rice flour CRM (normal, fortified) samples. Based on the
results of the experiment, it has been found that the proposed technique can be applied to the determination of Cu(II) in
various real samples.
The text was submitted by the authors in English. 相似文献
998.
Novel composite polymer electrolytes based on poly(ether-urethane) network polymer and fumed silicas
X. J. Wang H. P. Zhang J. J. Kang Y. P. Wu S. B. Fang 《Journal of Solid State Electrochemistry》2007,11(1):21-26
Novel composite solid polymer electrolytes (CSPEs) and composite gel polymer electrolytes (CGPEs) have been prepared. CSPE
consists of poly(ether-urethane) network polymer (PUN), fumed silicas and LiClO4. The ionic conductivity of CSPEs can be enhanced nearly 20 times in comparison with the plain system without the addition
of fumed silicas and can be above 1×10−5 S/cm at room temperature. The effects of both kinds of fumed silicas, viz. uSiO2 with hydrophilic groups at the surface and mSiO2 with hydrophobic groups at the surface on ionic conductivity were investigated. CGPE comprising of the CSPE and LiClO4–PC solution with good mechanical strength exhibits ionic conductivity in the order of 10−3 S/cm at room temperature and above 3×10−4 S/cm at low temperature −40 °C. 相似文献
999.
The effect of ginger root (Zingiberis Rhizoma) on gastrointestinal motility was examined based on its ability to enhance charcoal meal transport in mice. Oral administrations of the acetone extract of ginger (which contains volatile oils and bitter substances) at 75 mg/kg, [6]-shogaol at 2.5 mg/kg, or a [6]-, [8]- or [10]-gingerol at 5 mg/kg enhanced the transport of a charcoal meal. The effects of these substances were similar to or slightly weaker than those of metoclopramide and donperidone. 相似文献
1000.
The membrane destabilizing and fusogenic properties of the synthetic peptide VP3(110-121), corresponding to an immunogenic sequence of the hepatitis A virus (HAV) VP3 capsid protein, were studied. By tryptophan fluorescence and acryalmide quenching it was demonstrated that the peptide binds liposomes of POPC-SM-DPPE (47 + 39 + 14) and POPC-SM-DPPE-DOTAP (40 + 33 + 12 + 15) and penetrates the membrane, at both neutral and acidic pH (POPC = 1-palmitoyl-2-oleoylglycero-sn-3-phosphocholine; SM = sphingomyelin; DPPE = 1,2-dipalmitoylphosphatidylethanolamine; DOTAP = 1,2-dioleoyl-3-trimethylammoniumpropane). VP3(110-121) did not have membrane-destabilizing properties at neutral pH. Acid-induced destabilization of the vesicles was demonstrated by fluorescence techniques and dynamic light scattering. VP3(110-121) induced aggregation of POPC-SM-DPPE-DOTAP (40 + 33 + 12 + 15) vesicles, lipid mixing and leakage of vesicle contents, all consistent with fusion of vesicles. In POPC-SM-DPPE (47 + 39 + 14) vesicles, at acidic pH, VP3(110-121) induced membrane destabilization with leakage of contents but without aggregation of vesicles or lipid mixing. The peptide only showed fusogenic properties when bound to the vesicles at neutral pH before acidification to pH below 6.0, and no effect was seen if the peptide was added to vesicles already set at acidic pH. These results may have physiological significance in the mechanism of infection of host hepatic cells by HAV. 相似文献