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151.
Ehrlich G Hassfeld J Eggert U Kalesse M 《Journal of the American Chemical Society》2006,128(43):14038-14039
The first total synthesis of the (+)-tedanolide is described. Pivotal steps are the Felkin-selective aldol coupling between C12 and C13 and an efficient Mitsunobu macrolactonization. Selective protecting group transformations and subsequent oxidations generate the macrocyclic triketone. In the endgame of the synthesis, four TBS groups are removed in one reaction and a chemo- and stereoselective final step epoxidation generates (+)-tedanolide. 相似文献
152.
Langmuir-Blodgett assemblies of 1-palmitoyl-2-pyrenedecanoylphosphatidylcholine and dipalmitoylphosphatidylcholine were transferred from an air/water interface onto germanium or silicon attenuated total reflection (ATR) crystals and were investigated by Fourier transform infrared spectroscopy. A detailed attention has been paid to optimize the deposition conditions and to study the organization of transferred mono- and multimolecular layers. 相似文献
153.
Let A be an n × n matrix with real eigenvalues λ1 ? … ? λn, and let 1 ? k < l ? n. Bounds involving trA and trA2 are introduced for λk/λl, (λk ? λl)/(λk + λl), and {kλk + (n ? l + 1)λl}2/{kλ2k + (n ? l + 1)λ2l}. Also included are conditions for λl >; 0 and for λk + λl > 0. 相似文献
154.
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157.
We construct topological geon quotients of two families of Einstein-Yang-Mills black holes. For Künzle??s static, spherically symmetric SU(n) black holes with n?>?2, a geon quotient exists but generically requires promoting charge conjugation into a gauge symmetry. For Kleihaus and Kunz??s static, axially symmetric SU(2) black holes a geon quotient exists without gauging charge conjugation, and the parity of the gauge field winding number determines whether the geon gauge bundle is trivial. The geon??s gauge bundle structure is expected to have an imprint in the Hawking-Unruh effect for quantum fields that couple to the background gauge field. 相似文献
158.
Ruusunen J Tapanainen M Sippula O Jalava PI Lamberg H Nuutinen K Tissari J Ihalainen M Kuuspalo K Mäki-Paakkanen J Hakulinen P Pennanen A Teinilä K Makkonen U Salonen RO Hillamo R Hirvonen MR Jokiniemi J 《Analytical and bioanalytical chemistry》2011,401(10):3183-3195
Several studies have shown that combustion-derived fine particles cause adverse health effects. Previous toxicological studies on combustion-derived fine particles have rarely involved multiple endpoints and a detailed characterization of chemical composition. In this study, we developed a novel particle sampling system for toxicological and chemical characterization (PSTC), consisting of the Dekati Gravimetric Impactor (DGI) and a porous tube diluter. Physico-chemical and toxicological properties of the particles emitted from various combustion sources were evaluated in two measurement campaigns. First, the DGI was compared with the High-Volume Cascade Impactor (HVCI) and to the Dekati Low-Pressure Impactor (DLPI), using the same dilution system and the same sampling conditions. Only small differences were observed in the mass size distributions, total particulate matter (PM), and particulate matter with diameter smaller than 1 um (PM(1)) concentrations and geometric mass mean diameters (GMMD) between these three impactors. Second, the PSTC was compared with the HVCI sampling system, which has been optimal for collection of particulate samples for toxicological and chemical analyses. Differences were observed in the mass size distributions, total PM and PM(1) emissions, and GMMDs, probably due to the different sampling and dilution methods as well as different sampling substrates which affected the behavior of semi-volatile and volatile organic compounds. However, no significant differences were detected in the in vitro measurements of cytotoxicity between the samples collected with the PSTC and the HVCI systems. In measurements of genotoxicity, significant differences between the two sampling systems were seen only with the particles emitted from the sauna stove. In conclusion, due to compact size, PSTC is an applicable method for use in particle sampling as part of the toxicological and chemical characterization of particulate emissions from different combustion sources. It offers some advantages compared to the previously used high-volume sampling methods including compactness for field measurements, simple preparation of sample substrates and high extraction efficiency. 相似文献
159.
Anna Lähde Noora Kokkonen Antti J. Karttunen Sirpa Jääskeläinen Unto Tapper Tapani A. Pakkanen Jorma Jokiniemi 《Journal of nanoparticle research》2011,13(9):3591-3598
Atmospheric pressure chemical vapor synthesis was used to produce copper nanoparticle composites in an amorphous silicon dioxide,
i.e., either copper nanoparticles coated with amorphous silicon dioxide or copper nanoparticles embedded in amorphous silicon
dioxide matrix. Synthesized metal–organic copper(I) complex was used as a precursor that provided well-defined ratio (1:2)
of copper and silicon. The thermal decomposition of the Cu(I) complex molecule leads to homogenous nucleation and formation
of copper nanoparticles which are subsequently coated with Si/SiO2 in the gas phase. The decomposition was greatly enhanced when reductive atmosphere, i.e., H2/N2 10 v% were used instead of pure nitrogen. A narrow size distribution with the geometric mean diameter of the particle agglomerates
around 30 nm was observed while the primary size of the copper core particles was around 5 nm. 相似文献
160.
Let (P,?,∧) be a locally finite meet semilattice. Let