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51.
Turner B Shterenberg A Kapon M Suwinska K Eichen Y 《Chemical communications (Cambridge, England)》2002,(5):404-405
Trihalogenated compounds act as effective and selective templates in the template-assisted synthesis of meso-hexaphenyl-calix[6]pyrrole. 相似文献
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Michael M. Konnick Brian G. Hashiguchi Deepa Devarajan Nicholas C. Boaz T. Brent Gunnoe John T. Groves Niles Gunsalus Daniel H. Ess Roy A. Periana 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(39):10658-10662
Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate esters is achieved by a homogeneous hypervalent iodine(III) complex in non‐superacidic (trifluoroacetic acid) solvent. The reaction is highly selective for ester formation (>99 %). In the case of ethane, greater than 0.5 M EtTFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism. 相似文献
54.
Boaz Tsaban 《Topology and its Applications》2005,153(4):620-639
Whereas the Gerlits-Nagy γ property is strictly weaker than the Galvin-Miller strong γ property, the corresponding strong notions for the Menger, Hurewicz, Rothberger, Gerlits-Nagy (∗), Arkhangel'ski?ˇ and Sakai properties are equivalent to the original ones. The main result is that almost each of these properties admits the game theoretic characterization suggested by the stronger notion. We also solve a related problem of Ko?inac and Scheepers, and answer a question of Iliadis. 相似文献
55.
Dusan Repovs Boaz Tsaban Lyubomyr Zdomskyy 《Proceedings of the American Mathematical Society》2008,136(7):2515-2520
We show that even for subsets of the real line that do not contain perfect sets, the Hurewicz property does not imply the property , asserting that for each countable family of open -covers of , there is a choice function whose image is a -cover of . This settles a problem of Just, Miller, Scheepers, and Szeptycki. Our main result also answers a question of Bartoszyński and the second author, and implies that for , the conjunction of Sakai's strong countable fan tightness and the Reznichenko property does not imply Arhangelskiı's property .
56.
We have determined the isotope effects of (17)O and (18)O substitution of (16)O in H(2)O on molecular diffusivities of water vapor in air by the use of evaporation experiments. The derived diffusion fractionation coefficients (17)alpha(diff) and (18)alpha(diff) are 1.0146 +/- 0.0002 and 1.0283 +/- 0.0003, respectively. We also determined, for the first time, the ratio ln((17)alpha(diff))/ln((18)alpha(diff)) as 0.5185 +/- 0.0002. This ratio, which is in excellent agreement with the theoretical value of 0.5184, is significantly smaller than the ratio in vapor-liquid equilibrium (0.529). We show how this new experimental information gives rise to (17)O excess in meteoric water, and how it can be applied in isotope hydrology. 相似文献
57.
Nanostructured porous silicon (PSi) is an attractive platform for the design of biosensors because of its high sensitivity and selectivity towards various biological targets. Its use for biosensing applications, however, is compromised as a result of interfacial interactions with biological molecules that may accumulate on their surfaces and degrade their performance. We describe a new hybrid system comprising an oxidized PSi (PSiO2) nanostructure and antifouling (anti‐adsorption), light‐triggered pre‐polymers that promote crosslinking and surface anchoring to Si walls. The incorporation of the pre‐polymers allowed the production of a thick hydrogel layer on the inorganic nanostructure. Coating completely prevents fouling of proteins on the surface without compromising biosensor performance in terms of sensitivity. The strategy developed here provides a convenient means to combine two distinct features of crosslinking and organic–inorganic hybrid fabrication in a “one‐pot” process. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
58.
The class of spaces such that their product with every Lindelöf space is Lindelöf is not well-understood. We prove a number of new results concerning such productively Lindelöf spaces with some extra property, mainly assuming the Continuum Hypothesis. 相似文献
59.
AV Butenko E Mogilko L Amitai B Pokroy E Sloutskin 《Langmuir : the ACS journal of surfaces and colloids》2012,28(36):12941-12947
We employ real-time three-dimensional confocal microscopy to follow the Brownian motion of a fixed helically shaped Leptospira interrogans (LI) bacterium. We extract from our measurements the translational and the rotational diffusion coefficients of this bacterium. A simple theoretical model is suggested, perfectly reproducing the experimental diffusion coefficients, with no tunable parameters. An older theoretical model, where edge effects are neglected, dramatically underestimates the observed rates of translation. Interestingly, the coiling of LI increases its rotational diffusion coefficient by a factor of 5, compared to a (hypothetical) rectified bacterium of the same contour length. Moreover, the translational diffusion coefficients would have decreased by a factor of ~1.5, if LI were rectified. This suggests that the spiral shape of the spirochaete bacteria, in addition to being employed for their active twisting motion, may also increase the ability of these bacteria to explore the surrounding fluid by passive Brownian diffusion. 相似文献
60.