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61.
Experimental procedures were investigated to improve the efflux of biomolecule pyrolyzates from quartz tube pyrolysis under atmospheric pressure ionization mass spectrometry conditions. Heating regimes, airflows, and ion focusing parameters were optimized to increase the informative mass spectral signals generated from the pyrolysis of Gram-positive bacterial spores and vegetative cells. Dipicolinic acid (DPA) is found in 5-15% by weight in Gram-positive Bacillus spores, and the parameter optimization procedures provided an intense mass spectral signature of the m/z 168 protonated DPA molecule with a minimization of pyrolytic and ionization fragments. Moreover, mass spectral information from the optimization protocols yielded peaks and mass patterns characteristic of DNA and RNA nitrogen bases, protein diketopiperazines, and amino sugars.  相似文献   
62.
A simple method has been developed for the extraction, separation, and determination of synthetic colors in ice cream samples. The process involves the breakdown of emulsion by neutral detergents (Triton X-100 and Tween 20) followed by extraction with petroleum ether for removal of fat. The aqueous colored solution obtained is treated with 5% acetic acid, and the uptake of color is carried out by a wool-dyeing technique. The color is eluted from the wool with 5% ammonia solution, the solution is evaporated to dryness, and the residue is dissolved in 60% ethanol for paper chromatography using trisodium citrate-ammonia-water (2 + 5 + 95, w/v/v) as the mobile phase. The colored spots from the paper chromatogram are cut and eluted with 60% ethanol, and the absorbance is measured at the respective lambda maximum corresponding to the Rf value of the appropriate standard. The recoveries of 6 colors, including sunset yellow FCF (SSYFCF), tartrazine, carmoisine, ponceau 4R, brilliant blue FCF (BBFCF), and fast green FCF from spiked samples with either detergent were found to be >90%. However, recoveries of erythrosine were 21 and 65% with Triton X-100 and Tween 20, respectively. Indigo carmine could not be recovered at all because of its fugitive property in 5% ammonia solution, which is used to strip the color from the wool. The sensitivity of the method with the use of Tween 20 is 1 ppm (1 microg/g) for the colors in spiked ice cream samples. With this method, we analyzed samples of 20 branded colored ice cream. The results showed the presence of tartrazine (8.4-43.3 ppm), SSYFCF (23.5-117.6 ppm), carmoisine (traces-53.2 ppm), erythrosine (3.5 ppm), and BBFCF (4.1 ppm) in the ice cream samples. Apart from 2 samples of tuttifruity, all of the ice cream samples showed the presence of permitted synthetic colors below the permissible level of 100 ppm established by the Prevention of Food Adulteration Act of India.  相似文献   
63.
An ion chromatographic method has been developed for the determination of some microelements in different types of milk. It involves oxidative photodegradation of the organic matrix with H2O2 in a UV digester, equipped with a high-pressure mercury lamp. The temperature of the sample is maintained at 85±5 °C by a combined air/water cooling system. This procedure provides an efficient alternative to traditional dry ashing and wet digestion methods. Milk degrades in less than 2 h, while inorganic constituents, except for iodide, nitrate, nitrite, sulfite and manganese (II), are unaffected by UV radiation. Depending upon the type of milk (whole, skimmed, powdered, evaporated, etc.) to be analysed, the amount of sample and the UV photolysis time can be adjusted as per requirements. The clear solution resulting from the UV digestion is diluted, filtered and injected onto an ion chromatograph equipped with both conductivity and variable-wavelength UV-Vis detectors. The method has been tested with standards and real milk samples and has been found to be satisfactory for the determination of total chloride, bromide, phosphorus (as phosphate) and sulfur (as sulfate), and of copper, nickel, zinc, cobalt, iron and lead.  相似文献   
64.
Tracer diffusion of131I ions is studied at different temperatures /20°C–50°C/ in 2.5% agar gel containing sodium and potassium sulphate solutions over a wide range of concentrations. The results are in qualitative agreement with the theoretical values in the concentration range 10–6–10–1M. Agar gel shows an obstruction effect to diffusional flow. The activation energy for tracer diffusion was found to be of the order of 16.3 kJ mol–1.  相似文献   
65.
Hydroxypropyl chitosan-graft-carboxymethyl beta-cyclodextrin (HPCH-g-CM beta-CD) was synthesized by grafting CM beta-CD onto HPCH using water soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as the condensing agent. Due to the presence of hydrophobic beta-CD rings onto the HPCH backbone, this polymer can be used as a matrix for controlled drug release. The adsorption of a hydrophobic model drug, ketoprofen, by HPCH-g-CM beta-CD microparticles (using tripolyphosphate as an ionic crosslinking agent) fitted well in the Langmuir isotherm equation. The drug dissolution profile showed that HPCH-g-CM beta-CD microparticles provided a slower release of the entrapped ketoprofen than chitosan, and the release behavior was influenced by the pH value of the medium. These results suggest that beta-CD grafted with chitosan derivatives may become a potential biodegradable delivery system to control the release of hydrophobic drugs with pH-responsive capability.  相似文献   
66.
67.
We have studied the feasibility of producing57Co (271.3 d) via the55Mn(, 2n)57Co reaction (55Mn–100%). The thick target yield of57Co in the 28 to 18 MeV energy region was measured as 3.87 Ci/Ah. However, the proximity and overlap of the excitation functions for (, n), (, 2n) and (, 3n) reactions on55Mn are such that the production of pure57Co in high yields free of58Co (70.8 d) and56Co (78.8 d) has not been feasible. We have also studied a new method for ancillary production of57Co via the reactions58Ni(, p)57Co and during the course of producing62Zn by60Ni(, 2n)62Zn reaction. In this case the yield of57Co of reasonable purity has been up to 1 Ci/Ah.  相似文献   
68.
A library of 24 glycoconjugates related to glycosylated beta-amino acid derivative (I) was been prepared and screened against DNA topoisomerase-II of the filarial parasite S. cervi. Among these, compound 6 was found to be a potent inhibitor of DNA topoisomerase-II with 95% inhibition at 1.09 microM. Furthermore, compound 6 was at least three times more potent than the lead compound, glycosylated beta-amino acid derivative I.  相似文献   
69.
Zusammenfassung Es wurde das polarographische Verhalten von Indium(III) in verschiedenen Nitraten in Abhängigkeit von der Konzentration untersucht. Die Ergebnisse wurden unter besonderer Beachtung der Faktoren Viskosität, Diffusionskoeffizienten und Ionensolvatation interpretiert. Die scheinbaren Geschwindigkeitskonstanten wurden nach dem Verfahren vonDelahay bestimmt und ein quasireversibles Verhalten festgestellt.
Polarography of indium(III) in alkali and alkaline earth nitrates
Polarographic behavior of Indium(III) in several nitrates of varying concentrations has been studied and resuts interpreted in the light of factors viscosity, diffusion coefficients and ion solvation. The apparent rate constants were determined byDelahay's treatment which revealed its quasireversible behavior.


An den allfällige Korrespondenz zu richten ist.  相似文献   
70.
The 25% niobium substituted crystalline titanosilicate with the composition Na1.5Nb0.5Ti1.5O3SiO4·2H2O (Nb-TS) was synthesized under hydrothermal conditions. Its selectivity for radioactive 137Cs and 89Sr was compared with the TS, Na2Ti2O3SiO4·2H2O, having sitinakite topology. The Nb-TS shows significantly higher uptake value for 137Cs but lower for 89Sr than the TS. To investigate the origin of selectivity, the ion exchanged Cs+ and Sr2+ forms with the composition, CsxNaHyNb0.5Ti1.5O3SiO4·zH2O (x=0.1, 0.2 and 0.3, x+y=0.5 and z=1-2) and Sr0.2Na0.6H0.5Nb0.5Ti1.5O3SiO4·H2O, respectively, were structurally characterized from the X-ray powder diffraction data using the Rietveld refinement technique. Simultaneously the kinetics of 137Cs and 89Sr uptake was investigated for the NbV free and doped samples. While the Cs+ and Sr2+ exchanged form of Nb-TS and the Cs+ exchanged form of TS retain the symmetry of the parent compound, the Sr2+ exchanged form of TS undergoes a symmetry change. The differences in the uptake of Cs+ and Sr2+ result from the different coordination environments of cesium and strontium in the eight-ring channel, that result from various hydration sites in the tunnel. The origin of selectivity appears to arise from the higher coordination number of cesium or strontium. Other effects due to NbV substitution are reflected in the increase of both, the a- and c-dimensions and thus the unit cell volume, and the population of water vs. Na+ in the channel to charge-balance the Nb5+↔Ti4+ substitution.  相似文献   
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