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41.
Abstract— Dimerization of uracil monomers in a polycrystalline state by UV radiation changes the absorption characteristics of a thin layer of the material. The change in optical density, measured by spectrophotometry in the250–400 nm range, as a function of the exposure time is evaluated in terms of the biologically effective UV dose. A statistical evaluation of a great number of uracil dosimeters irradiated with a TL01 lamp from Philips establishes the possibility of evaluating the biologically effective UV dose using a uracil dosimeter. Nonlinear regression procedures were introduced to correct the absorption spectra for contributions due to light scattering and to determine the optical density values required to calculate the UV dose expressed in HU units. Comparison of cumulative daily doses and long-term monitoring measured by the uracil thin-layer dosimeter and a phage T7 dosimeter are given, which allow the determination of conversion factors between various biological dosimeters under different irradiation conditions. 相似文献
42.
An amperometric method for the determination of thiocarbamyl sulphonamides has been developed, based on the cleavage of the S-N bond by hydriodic acid. The method can also be applied for the cleavage of the S-S bond in thiuram disulphides and dibenzothiazyl disulphide, and thus provides a useful means for the estimation of these compounds as well. 相似文献
43.
Krishna C. Joshi Vijai N. Pathak Raj Pal Singh 《Monatshefte für Chemie / Chemical Monthly》1980,111(6):1343-1350
Several new 2-(fluoroaryl)-3-dialkylaminomethylindoles, 3-acetyl-2-(fluoroaryl)-indoles, 2-(fluoroaryl)-3-indolylglyoxamides and corresponding tryptamines have been prepared as possible psychopharmacological agents. 2-(Fluoroaryl)-indoles have been synthesized by theFischer indole synthesis. 2-(Fluoroaryl)-indoles on treatment with oxalyl chloride and subsequent reaction with amines, gave 2-(fluoroaryl)-3-indolylglyoxamides. Some of these indolylglyoxamides were reducted with lithium aluminium hydride, to the corresponding tryptamines. 2-(Fluoroaryl)-indoles when subjected toMannich reaction afforded 3-dialkylaminomethyl-2-(fluoroaryl)-indoles. All these new compounds have been characterized by IR spectral studies.Possible Psychopharmacological Agents, Part XII, Part XI, J. Indian. Chem. Soc.57, 423 (1980). 相似文献
44.
Sanyal A Rautaray D Bansal V Ahmad A Sastry M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7220-7224
We show here that reaction of the fungus, Fusarium oxysporum, with the aqueous heavy-metal ions Pb2+ and Cd2+ results in the one-step formation of the corresponding metal carbonates. The metal carbonates are formed by reaction of the heavy-metal ions with CO2 produced by the fungus during metabolism and thus provide a completely biological method for production of crystals of metal carbonates. The PbCO3 and CdCO3 crystals thus produced have interesting morphologies that are shown to arise because of interaction of the growing crystals with specific proteins secreted by the fungus during reaction. An additional advantage of this approach is that the reaction leads to detoxification of the aqueous solution and could have immense potential for bioremediation of heavy metals. Under conditions of this study, the metal ions are not toxic to the fungus, which readily grows after exposure to the metal ions. 相似文献
45.
2,8-Dimethyltricyclo[6.2.2.01,6]dodeca-2,5-diene-4,9-dione (
), 2,9-dimethyltricyclo [6.3.1.01,6]dodeca-2,5-diene-4,10-dione (
) and 2-methyltricyclo[6.3.1.01,6]dodeca-2,5-diene-4,10-dione (
) have been synthesised for entry into the ring systems of a few tetracyclic diterpenes. 相似文献
46.
Molecular mechanism of physical gelation of hydrocarbons by fatty acid amides of natural amino acids
Asish Pal 《Tetrahedron》2007,63(31):7334-7348
A variety of fatty acid amides of different naturally occurring l-amino acids have been synthesized and they are found to form gels with various hydrocarbons. The gelation properties of these compounds were studied by a number of physical methods including FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, rheology, and it was found that gelation depended critically on the fatty acid chain length and the nature of the amino acid. Among them l-alanine based gelators were found to be the most efficient and versatile gelators as they self-assemble into a layered structure to form the gel network. Mechanisms for the assembly and formation of gels from these molecules are discussed. 相似文献
47.
Summary In acid (HClO4) medium CeIV is reduced to CeIII by 8-hydroxyquinoline (1) and its derivatives, the 5-sulphonate (2) and 7-iodo-5-sulphonate (3), through precursor complex formation. The rates of precursor complex formation have been studied by stopped-flow spectrophotometry for both (1) and (2). Formation of the precursor complex occurs in two concurrent paths involving Ce
aq
4+
and [Ce(OH)]
aq
3+
reacting by Ia and Id processes respectively. The reaction with (3) is, however, too fast for the stopped-flow method. The rates for subsequent intramolecular electron transfer processes in the precursor complexes are sufficiently slow for all the three species(1)–(3) for evaluation by conventional spectrophotometry. For the electron transfer process the rate varies in the sequence:(2)>(1)(3) due to electron-withdrawing character of the substituent SO
3
–
and electron-releasing character of I. 相似文献
48.
A very simple, highly-sensitive and selective quenchofluorimetric method for the rapid determination of molybdenum(VI) in aqueous media is described. The method is based on the instantaneous quenching action by the metal-ion upon the native fluorescence of bathophenanthrolinedisulphonate (4,7-diphenyl-1,10-phenanthrolinedisulphonate) solution [lambda(ex) (max) 288 nm; lambda(em) (max) 444.8 nm] in the optimum pH-range of 3.0-3.7 at room temperature (25 +/- 5 degrees ). The fluorescence quenching is co-linear in the range of 0.01-1.0 ppm molybdenum. Large excesses of over 50 cations, anions and some common complexing agents were found to have no interference. Cu, Ni, Co, Fe and V can be tolerated only up to the corresponding amount of molybdenum. Interference from greater amounts can however be removed by a one-step ion-exchange separation process. The developed method was successfully tested over several standard alloys, synthetic mixtures of various compositions, factory effluents and in spiked environmental waters. 相似文献
49.
Ionic discotic liquid crystals: synthesis and characterization of pyridinium bromides containing a triphenylene core 总被引:1,自引:0,他引:1
Five novel pyridinium salts tethered with hexaalkoxytriphenylene molecules were synthesized by the quaternization of pyridine with ω-bromo-substituted triphenylene derivatives. Their chemical structures were determined by 1H NMR, 13C NMR, IR, UV spectroscopy and elemental analysis. The thermotropic liquid crystalline properties of these salts were investigated by polarizing optical microscopy and differential scanning calorimetry. These triphenylene-based pyridinium salts with bromide as counterion were found to be mesomorphic over a wide temperature range. 相似文献
50.
B. S. Randhawa Anand Pal Singh R. P. Sharma P. S. Bassi 《Journal of Radioanalytical and Nuclear Chemistry》1988,128(3):165-179
The solid state reactions between ferrous oxalate dihydrate i.e. FeC2O4.2H2O and unsubstituted/ substituted aniline hydrochlorides have been studied. The products [FeCl/oxH/. AN-Cl] have been characterized by elemental analysis, infrared and Mössbauer spectroscopic techniques. The kinetic studies for the reactions have been performed at various temperatures for fixed particle sizes at constant compaction. The following order of reactivity has been observed: unsubstituted > p-substituted > m-substituted o-substituted. 相似文献