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61.
Robert J. Houben Hans-Gerd M. Janssen Piet A. Leclercq Jacques A. Rijks Carel A. Cramers 《Journal of separation science》1990,13(10):669-673
A simple and versatile system is described for the on-line coupling of SFE to capillary GC. The interfacing consists of a programmed temperature vaporizer (PTV) injector. With this injector it is possible to combine solute trapping, elimination of a high flow of extraction fluid, and quantitative transfer of solutes to the seperation column. The problems caused by impurities in the extraction fluid in on-line SFE-GC are discussed. Simple methods are described for the purification of commercially available carbon dioxide. The trapping efficiency of the PTV injector is studied. Applications of the SFE-PTV-GC system are given for the analysis of polymer anti-degradants, polar compounds, and samples with environmental relevance. 相似文献
62.
Alain H. Roux Daniel Hétu Gérald Perron Jacques E. Desnoyers 《Journal of solution chemistry》1984,13(1):1-25
Mixed micelles can be formed in water between various pairs of hydrophobic solutes such as surfactants, alcohols and hydrocarbons. These systems can often be studied through the thermodynamic functions of transfer of one of the solutes, usually kept near infinite dilution, from water to an aqueous solution of the other solute. When mixed micelles are formed, these functions change significantly, and often go through extrema, in the region where the binary system micellizes or undergoes some microphase transition.Three main effects are responsible for the observed trends: pair-wise interactions between both solutes in the monomeric form, a distribution of the reference solute between the aqueous and micellar phases and a shift in the monomer-micelle equilibrium in the vicinity of the reference solute. Simple equations can be derived for these three effects which can account for the sign and magnitude of the observed trends using parameters which are derived for the most part from the two binary systems. 相似文献
63.
Nicole Brasseur Karina Lewis Jacques Rousseau Johan E. van Ller 《Photochemistry and photobiology》1996,64(4):702-706
Abstract— The clinical perfusion agent 99m Tc-MIBI was used to monitor changes in tumor vascular perfusion (TVP) induced by Photofrin® (Pll)-mediated photodynamic therapy (PDT). BALB/c mice bearing an EMT-6 tumor on each hind thigh were given an intravenous injection of 1, 2 or 5 mg kg−1 PII. Twenty-four hours later, one tumor was illuminated (600–650 run, 200 mW cm−2 400 J cm−2 ) while the other served as a control. At various time intervals after PDT (0, 2 and 24 h) mice received an intravenous injection of 99m Tc-hexakismethoxy(sobutyusonitri-le (MIBI) (0.18 MBq g−1 ) and were sacrificed 2 min later. The light-treated and the untreated tumors were then dissected, the radioactivity was counted and the percentage of the injected dose per gram of tumor (%ID g−1 ) was calculated as a measure of TVP. We observed that TVP is drug dose dependent, develops progressively with time post-PDT and is inversely related to PDT efficacy. Our data show that early tumor retention of 99m MIBI is a simple method to assess TVP and vascular damage induced by PDT. 相似文献
64.
Merdy P Guillon E Aplincourt M Dumonceau J Vezin H 《Journal of colloid and interface science》2002,245(1):24-31
Spectroscopic and physicochemical data, X-ray photoelectron spectroscopy (XPS), solid-state (13)C cross-polarization magic-angle-spinning NMR, GC/MS, specific surface area, site density, and surface acidity constants have been recorded or determined for a ligno-cellulosic substrate (LS) extracted from straw. Its copper(II)-bound ability has also been studied. The LS solid that exhibits two types of binding sites, carboxylic and phenolic groups, has a great affinity for copper(II), with a maximum of adsorption at around 4 mg g(-1) as early as the pH reaches 6. The structural characterization of the Cu(II) surface complexes has been investigated using EPR spectroscopy. The CuO(4) chromophore of the inner-sphere surface complexes is a slightly distorted square. A surface oxidation occurred simultaneously, which leads to semiquinonic radicals. Furthermore, our empirical approach, which used a correlation between thermodynamics data and EPR parameters, has led to a surface complexation constant log beta equal to 12.6. This indicates that copper(II) surface complexes are relatively stable. 相似文献
65.
Ibra Gueye Dioum Jacques Vedel Bernard Tremillon 《Journal of Electroanalytical Chemistry》1982,137(2):219-226
Molten potassium tetrachlorogallate and potassium tetraiodogallate were studied in terms of halogenoacidity, based on X? ion-exchange. Titration of KX solution with GaX3 were achieved and characterized by the shift of cathodic voltammetric curves. Autodissociation constants Ki,X/mol2 kg?1 were determined: ?log Ki,Cl=4.25±0.05 and ?log Ki,I=2.6±0.05, as well as the solubility values of KX: 0.41±0.02 and 0.80±0.02 mol kg?1 for KCl and KI respectively. 相似文献
66.
A general method of annellating quinones in high yield has been devised using mixed vinylketene acetals obtained directly from the enolate ions of unsaturated esters. 相似文献
67.
Jean Favre-Bonvin katia Gluchoff-Fiasson Jacques Bernillon 《Tetrahedron letters》1982,23(18):1907-1908
Stearyl-velutinal, a new natural sesquiterpenoi̋d isolated from lactarius velutinus Bert., has the structure ; this very labile compound is responsible for the dark-blue reation of the fungus to the ‘sulfo-vanilic’ mixtures. 相似文献
68.
Jacques Piette Claire-M. Calberg-Bacq Albert van de Vorst 《Photochemistry and photobiology》1977,26(4):377-382
Abstract. Thiols and disulfides protect both φX174 phage and its isolated DNA from the lethal action of proflavine plus light. The protective ability of these compounds appears to be attributed to the -SH or the -S-S- group and the property to interact with the proflavine-phage DNA complex. The phage inactivation efficiency per proflavine bound to DNA is reduced by 50 to 30% upon addition of cysteine or cystamine. Substances that affect the lifetime of singlet oxygen modify the rate of phage photoinactivation in the presence of proflavine; the inactivation rate is decreased by N- 3 and increased by D2 O. Irradiation under N2 atmosphere markedly decreases the phage photosensitization by proflavine. Irradiation with monochromatic light of 440 nm is less efficient than irradiation with light of 440 nm plus 360 nm, and the difference is more pronounced in N2 than in air. These results are discussed in relation to various possible photochemical pathways. 相似文献
69.
The Reaction of Norbornene with Lead Tetraacetate and Thallium Trinitrate. Preliminary communication
Jacques Kagan 《Helvetica chimica acta》1972,55(7):2356-2359
The reaction of norbornene with lead tetraacetate is found to be much more complex than previously reported. In acetic acid and in benzene, the syn-7-norbornenyl, 3-nortricyclyl, and syn and anti-7-acetoxy-exo-2-norbornyl acetates were characterized. In methanol, the isolated products represented most of those expected from the competition of methanol and acetate in the neutralization of the intermediate carbocations. The reaction of norbornene with thallium trinitrate in the above solvents yielded very complex mixtures besides the above mentioned products which were formed in about 50% yield. 相似文献
70.
This review gives a survey of the approaches employed to obtain, enhance and tune selectivity in nonaqueous capillary electrophoresis (NACE). Recent developments in NACE are described and the effects of background electrolyte composition and addition of selectors on separation selectivity are discussed. The use of one organic solvent, a mixture of several organic solvents or the use of additives to tune separation selectivity in NACE is presented and a list of relevant applications is included. 相似文献