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121.
Ultrathin, large nylon capsules whose porous membranes were corked with charged, synthetic bilayer-forming amphiphiles (cationic, anionic, zwitterionic bilayers) were prepared. The chemically stable, bilayer-corked capsules can selectively retain 0.1 M aqueous acidic (HCl, HNO3, H2SO4, HClO4 and p-toluenesulfonic acid) and alkaline solutions (NaOH, Ba(OH)2, NH4 OH, and N(Et)4OH) in the inner aqueous phase depending on the surface charge of corking bilayers: the capsule corked with positively and negatively charged bilayers could selectively store alkalies and acids, respectively, and could keep a selective pH-gradient across the membrane. The zwitterionic bilayer-corking could retain neither acids nor alkalies in the inner aqueous phase. The permeation of these acids and alkalies to the outer phase (pH gradient decreasing across the capsule membrane) could be reversibly controlled by the phase transition of corking bilayers from gel to liquid crystalline state. The selective storage and permeation of acids and alkalies could be explained by the process of permeation of H+ or OH- counter ions across the charged bilayer-corking. 相似文献
122.
The effect of molecular vibrations on electronic transport is investigated with the smallest fullerene C20 bridge, utilizing the Keldysh nonequilibrium Green's function techniques combined with the tight-binding molecular-dynamics method. Large discontinuous steps appear in the differential conductance when the applied bias voltage matches particular vibrational energies. The magnitude of the step is found to vary considerably with the vibrational mode and to depend on the local electronic states besides the strength of electron-vibration coupling. On the basis of this finding, a novel way to control the molecular motion by adjusting the gate voltage is proposed. 相似文献
123.
Spatiotemporal correlations of earthquakes are studied numerically on the basis of the one-dimensional spring-block (Burridge-Knopoff) model. As large events approach, the frequency of smaller events gradually increases, while, just before the mainshock, it is dramatically suppressed in a close vicinity of the epicenter of the upcoming mainshock, a phenomenon closely resembling the "Mogi doughnut." 相似文献
124.
We introduce Hilbert phase microscopy (HPM) as a novel optical technique for measuring high transverse resolution quantitative phase images associated with optically transparent objects. Because of its single-shot nature, HPM is suitable for investigating rapid phenomena that take place in transparent structures such as biological cells. The potential of this technique for studying biological systems is demonstrated with measurements of red blood cells, and its ability to quantify dynamic processes on a millisecond scale is exemplified with measurements of evaporating micrometer-sized water droplets. 相似文献
125.
Kuriyama M Soeta T Hao X Chen Q Tomioka K 《Journal of the American Chemical Society》2004,126(26):8128-8129
A catalytic asymmetric arylation of sterically tuned imines with arylboroxines was developed by using N-Boc-l-valine-connected amidomonophosphane rhodium(I) catalyst in n-PrOH. The TMS group used for the steric tuning of imines is convertible to other functionalities that are applicable as a key foothold for the carbon-carbon bond-forming coupling reactions. 相似文献
126.
The universal features of quantized thermal conductance of carbon nanotubes (CNTs) are revealed through a theoretical analysis based on the Landauer theory of heat transport. The phonon-derived thermal conductance of semiconducting CNTs exhibits a universal quantization in the low-temperature limit, independent of the radius or atomic geometry. The temperature dependence follows a single curve given in terms of temperature scaled by the phonon energy gap. The thermal conductance of metallic CNTs has an additional contribution from electronic states, which also exhibits quantized behavior up to room temperature. 相似文献
127.
Takahiro Hosokawa Hiromi NakanoKazuto Takami Kazuya KobiroAkinobu Shiga 《Tetrahedron letters》2003,44(6):1175-1177
Treatment of rubrene (5,6,11,12-tetraphenylnaphthacene) with trifluoroacetic acid in dichloromethane gives 4b,9,10-triphenyl-4b,9-dihydroindeno[1,2,3-fg]naphthacene (1) as the sole isolable product. Paired interacting orbital (PIO) analysis indicates that the reaction is initiated by preferential attack of H+ at C(11) position of rubrene. 相似文献
128.
Yajima T Wakabayashi N Uchida H Watanabe M 《Chemical communications (Cambridge, England)》2003,(7):828-829
Adsorbed water molecules which promote the methanol oxidation reaction (MOR) at Pt-Ru alloy electrode are clearly detected by in-situ FTIR spectroscopy with the attenuated total reflection configuration, which directly supports the "bi-functional mechanism" for the MOR. 相似文献
129.
130.