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Groth C Nydén M Persson KC 《Langmuir : the ACS journal of surfaces and colloids》2007,23(6):3000-3008
Interactions between benzyl benzoate and two different twin-tailed cationic surfactants have been studied. NMR diffusometry measurements have shown that cationic micelles grow in one dimension when benzyl benzoate is added. The location of benzyl benzoate in the micelles was evaluated by NOESY, showing that benzyl benzoate gave cross-peaks both to the hydrophobic groups in the surfactant and to the surfactant head group. Additions of benzyl benzoate to a lamellar phase of double-tailed quaternary surfactants revealed differences in responses. With an increasing concentration of benzyl benzoate, the structure of the dialkyl quat aggregate goes from lamellar to cubic, while the dialkyl ester quat forms a lamellar structure for all benzyl benzoate concentrations. 相似文献
114.
Cecilia Rodríguez de Barbarín Sylvain Berns Francisco Snchez‐Viesca Martha Berros 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(7):o360-o362
In the structure of the title compound, C10H8BrNS, the dihedral angles between the planes of the thiazole and aryl rings, viz. 4.2 (6) and 7.5 (6)° for the two independent molecules, are consistent with insignificant molecular perturbation by the weak intermolecular contacts. The molecules are close to being related by a non‐crystallographic inversion centre, with C—H⃛π and π–π intermolecular interactions observed. 相似文献
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Microwave irradiation facilitated the synthesis of 4-arylthio-3-oxazolin-5-ones from ethyl cyanoformate, thiophenol, and cyclic ketones. Subsequent decarboxylation and in situ [3+2] cycloaddition provided novel 2,3,4,5-tetrahydro-1H-pyrrolo[1,2-c][1,3]diazepine scaffolds after a spontaneous retro-Mannich domino reaction. 相似文献
117.
David P. DiPrete Cecilia C. DiPrete Edward A. Kyser Mira A. Malek 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):581-584
The Savannah River Site’s (SRS) H-Canyon facility uses ceric ammonium nitrate (CAN) to separate impure neptunium (Np) from a nitric acid feed stream containing 0.5–1.0 M concentrations of iron, sodium and sulfate impurities. The material is processed using a two-pass solvent extraction purification which relies on CAN to oxidize Np to Np(VI) during the first pass prior to extraction. Spectrophotometric oxidation-state analyses normally used to validate successful oxidation to Np(VI) prior to extraction were compromised by this feed stream matrix. Therefore, a rapid chromatographic method to validate successful Np oxidation was developed using Eichrom Industries’ TRU and TEVA® resins. The method was validated and subsequently transferred to existing operations in the process analytical laboratories. 相似文献
118.
M. Mazzera A. Baraldi E. Buffagni R. Capelletti N. Chiodini F. Moretti A. Vedda P. Bohacek 《Journal of Non》2011,357(8-9):1916-1920
Fourier transform absorption spectroscopy in the 500–6000 cm? 1 and 9–300 K ranges is applied to monitor the effects produced by Eu3+ incorporation into sol–gel silica samples doped with concentration increasing from 0.001 to 10 mol%. The aim is to investigate the formation of aggregates by exploiting the Eu3+ crystal-field transitions. Complementary microreflectance and Raman spectra are also measured in the range of silica intrinsic vibrational modes to confirm the hypothesis of matrix modification induced by increasing doping levels. Evidences of clustering are found for high Eu3+ concentrations. Up to 3 mol% the crystal-field line intensities gradually increase and the OH? content smoothly decreases. A further increase to 10 mol% causes drastic, remarkable changes, i.e. sharp crystal-field lines appear which narrow by lowering the temperature. Furthermore, the OH? related bands are no longer detectable. For concentrations up to 3 mol% the aggregates are amorphous as the silica matrix, while for the Eu3+ 10 mol% sample they show a rather ordered structure. 相似文献
119.
Repositories for the disposal of radioactive waste generally rely on a multi-barrier system to isolate the waste from the biosphere. This multi-barrier system typically comprises the natural geological barrier provided by the repository host rock and its surroundings and an engineered barrier system (EBS). Bentonite is being studied as an appropriated porous material for an EBS to prevent or delay the release and transport of radionuclides towards biosphere. The study of pore water chemistry within bentonite barriers will permit to understand the transport phenomena of radionuclides and obtain a database of the bentonite-water interaction processes. In this work, the measurement of some chemical parameters in bentonite pore water using solid-state microsensors is proposed. Those sensors are well suited for this application since in situ measurements are feasible and they are robust enough for the long periods of time that monitoring is needed in an EBS. A probe containing an ISFET (ion sensitive field effect transistor) for measuring pH, and platinum microelectrodes for measuring conductivity and redox potential was developed, together with the required instrumentation, to study the chemical changes in a test cell with compacted bentonite. Response features of the sensors’ probe and instrumentation performance in synthetic samples with compositions similar to those present in bentonite barriers are reported. Measurements of sensors stability in a test cell are also presented. 相似文献
120.
Dall'Acqua S Viola G Giorgetti M Loi MC Innocenti G 《Chemical & pharmaceutical bulletin》2006,54(8):1187-1189
As a part of our ongoing interest in new bioactive compounds from natural sources, we studied Laurus nobilis (Lauraceae). This plant is widespread in the Mediterranean area and is used for medicinal and economic purposes. Chromatographic separations on active extracts led to the isolation of two new sesquiterpene lactones, 5a,9-dimethyl-3-methylene-3,3a,4,5,5a,6,7,8-octahydro-1-oxacyclopenta[c]azulen-2-one (1) and 3beta-chlorodehydrocostuslactone (2). The structures of the new compounds were identified by 1D and 2D NMR experiments, as well as high resolution mass spectrometry. The cytotoxic activity was also evaluated against three different tumor cell lines of human origin. 相似文献