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51.
[reaction: see text] Olefin cross-metathesis has been used to prepare alpha-C-galactosylceramide derivatives. The metathesis process merged vinyl and propenyl glycosides with vinyl derivatives of phytosphingosine. The use of ethylene enhanced the yield of the methathesis step. 相似文献
52.
Herbarth O Rolle-Kampczyk U Franck U Rehwagen M Weiss H Krumbiegel P 《Isotopes in environmental and health studies》2004,40(1):69-74
The effect of remediation activities in formerly high-loaded industrial areas is measured conventionally in terms of decreased toxic loads. It is more difficult to investigate the effect on physiological parameters of the people living there. A non-invasive 15N-based organ function test, the [15N]methacetin urine test, was adapted to environmental-medical purposes for the detection of small deviations from the norm-range hepatic detoxification capacity. Parallel to the measurement of region-specific external exposure (especially by tri- and tetrachloro ethylene) and of the corresponding internal load (urinary trichloro acetic acid), the hepatic mono oxygenation capacity was determined. The study cohort consisted of 35 kindergarten children who were 3.3+/-0.5 years old at the beginning of the study. They lived in a high-polluted industrial village (n = 23) and in a non-polluted control village close by (n = 12), respectively. Children living in the polluted area were exposed a 2.3 times higher load and showed detoxification capacities 6% lower than the children in the control area. Improvement of the environmental situation led to exposure data decreasing by 70%, which is also reflected in smaller internal load and improved liver detoxification of the children in the polluted area. Then, between loaded and control area the mean hepatic detoxification was no longer significantly different (0.6%). The study shows that chronic low-dose exposure can disturb a hepatic function and that thereafter the capacity is recovered quickly in children. The stable isotope-based test is suited to characterize a health effect of multicomponent exposure by bioeffect monitoring within the framework of screening and testing the remediation efficiency. 相似文献
53.
Zapf A Jackstell R Rataboul F Riermeier T Monsees A Fuhrmann C Shaikh N Dingerdissen U Beller M 《Chemical communications (Cambridge, England)》2004,(1):38-39
A practical synthesis of a novel class of phosphine ligands, phosphino substituted N-aryl pyrroles (PAP ligands), has been developed. These ligands are applied in the palladium-catalyzed coupling of a variety of aryl and heteroaryl chlorides with phenylboronic acid showing exceedingly high turnover numbers at mild reaction temperatures and even at room temperature. 相似文献
54.
We formulate a framework to extend the idea of Berry's topological phase to multiple light scattering, and in particular to backscattering of linearly polarized light. We show that the randomization of the geometric Berry's phases in the medium leads to a loss of the polarization degree of the light, i.e., to a depolarization. We use Monte Carlo simulations in which Berry's phase is calculated for each photon path. Then we average over the distribution of the geometric phases to calculate the form of the patterns, which we compare with experimental patterns formed by backscattered light between crossed or parallel polarizers. 相似文献
55.
The topological analysis of grids of data is used for determination of surfaces or volumes around maxima. The volumes are then related to chemical information such as atoms or bonds, and can be used for integration of local properties such as electronic population. The problem of global connectivity is reversed into the question of local connectivity yielding a linear scaling partition algorithm. Two packages are developed for a very fast analysis and partition of 2D or 3D grids of data, applications being made to C2H2, C2H4, C6H6, H2CO, and H2CS molecules using the Atoms in Molecule (AIM) or Electron Localization Function (ELF). 相似文献
56.
An unusual heterodiene, an indolothiono quinone, undergoes cycloaddition with a glycal to form an indole-N-glycoside. A novel dimer of the indolothionoquinone is assigned its structure on the basis of a match between its predicted and observed IR spectrum. 相似文献
57.
Microwave heating methods have been combined with the use of solid-supported catalysts to produce small solution-phase libraries of medicinally-relevant compounds. Palladium supported on charcoal (Pd/C) has been used to produce libraries of pyrazole compounds for screening in COX II studies via Suzuki cross coupling reactions, while the same catalyst has been used also to produce styryl-based nAChR compounds using analogous chemistry. Although the reaction substrates are very different (aryl vs. vinyl), this catalyst system provided consistently good and reliable results. The use of a polystyrene-supported Ru catalyst for ring-closing metathesis (RCM) reactions was also evaluated to prepare benzolactam structures for evaluation as factor Xa inhibitors. 相似文献
58.
Novel polyesteramide-based di- and triblock copolymers: From thermo-mechanical properties to hydrolytic degradation 总被引:1,自引:0,他引:1
Gaëlle Deshayes Cécile Delcourt Ingrid Verbruggen Lise Trouillet-Fonti Franck Touraud Etienne Fleury Philippe Degée Mathias Destarac Rudolph Willem Philippe Dubois 《European Polymer Journal》2011,(1):98-110
Two types of biodegradable poly(ε-caprolactone (CLo))-co-poly(ε-caprolactam (CLa)) copolymers were prepared by catalyzed hydrolytic ring-opening polymerization. For the first type of materials, the respective cyclic comonomers were added simultaneously in the reaction medium leading to the formation of copolymers having a random distribution of co-units within the polyesteramide sequence, as evidenced by 1H and 13C NMR. For the second type of copolymers, the cyclic comonomers were added sequentially in the reaction medium yielding diblock polyesteramides, again evidenced by NMR. The thermal and thermo-mechanical properties of the copolymers were investigated by DSC and DMA and correlated with the copolymer topology and composition. The copolymers were characterized by a storage modulus and α transition temperature intermediate to the modulus and Tg of the corresponding homopolymers. The chemical composition and molecular weight of the copolymers proved to have only a limited effect on the thermo-mechanical properties of the materials. The hydrolytic degradation of random copolymers was studied in a phosphate buffer at 60 °C and discussed in terms of chemical composition and molecular weight of the copolymers. 相似文献
59.
Franck Tessier François Cheviré Odile Merdrignac-Conanec Michel Bouchard 《Journal of solid state chemistry》2008,181(5):1204-1212
Several approaches have been investigated to prepare fluorite-type compositions within the (1−x) CeO2-xYO1.5 system. The optical properties of the resulting modified-ceria materials have been characterized in order to evaluate their potential abilities as inorganic UV absorbers. Diffuse reflectance analyses reveal a strong optical absorption between 390 and 400 nm for all substituted compositions and the spectral selectivities are estimated suitable for the targeted application. Additionally, time resolved microwave conductivity (TRMC) and phenol photodegradation analyses do not indicate any photocalatytic activity for these compositions. Aqueous colloidal suspensions of the Ce0.7Y0.3O1.85 UV absorber have been carried out. 相似文献
60.