Binding constants for -cyclodextrin ( -CD) complexes with 1- alkanols and 1- alkanoate ions were determined by analyzing changes ( ) in chemical shifts of guest 13C NMR signals with -CD concentration. The guests gave well-separated 13C NMR signals. The curve-fitting analyses of for individual carbons upon assumption of a simple 1:1 complexation gave virtually the same binding constants (K1) in the cases of guests with relatively short alkyl chains, such as 1-propanol, 1-butanol, 1- pentanol , 1- butanoate , 1- pentanoate , and 1-hexanoate. However, thus obtained individual K1 values were significantly different from one another, when the guests had relatively long alkyl chains such as 1- hexanol , 1- heptanol , and 1-octanoate. In these guests, satisfactorily consistent K1 values were obtained by the curve-fitting analyses of for individual carbons upon an assumption that not only 1:1 but also 2:1 (host:guest) complexation occurs. 相似文献
Zeolites adsorb microbial cells on their surfaces and selective adsorption for specific microorganisms was seen with certain zeolites. Tests for the adsorption ability of zeolites were conducted using various established microbial cell lines. Specific cell lines were shown to selectively absorb to certain zeolites, species to species.
In order to understand the selectivity of adsorption, we tested adsorption under various pH conditions and determined the zeta-potentials of zeolites and cells. The adsorption of some cell lines depended on the pH, and some microorganisms were preferentially adsorbed at acidic pH. The values of zeta-potentials were used for calculating the electric double layer interaction energy between zeolites and microbial cells. There was a correlation between the experimental adsorption results and the interaction energy. Moreover, we evaluated the surface hydrophobicity of bacterial cells by using the microbial adherence to hydrocarbon (MATH) assay. In addition, we also applied this method for zeolites to quantify relative surface hydrophobicity. As a result, we found a correlation between the adsorption results and the hydrophobicity of bacterial cells and zeolites. These results suggested that adsorption could be explained mainly by electric double layer interactions and hydrophobic interactions.
Finally, by using the zeolites Na-BEA and H-Y, we succeeded in clearly separating three representative microbes from a mixture of Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Zeolites could adsorb each of the bacterial cell species with high selectivity even from a mixed suspension. Zeolites can therefore be used as effective carrier materials to provide an easy, rapid and accurate method for cell separation. 相似文献
Electrical properties of Schottky- and metal-insulator-semiconductor (MIS)-gate SiGe/Si high electron mobility transistors (HEMTs) were investigated with capacitance-voltage (C-V) measurements. The MIS-gate HEMT structure was fabricated using a SiN gate insulator formed by catalytic chemical vapor deposition (Cat-CVD). The Cat-CVD SiN thin film (5 nm) was found to be an effective gate insulator with good gate controllability and dielectric properties. We previously investigated device characteristics of sub-100-nm-gate-length Schottky- and MIS-gate HEMTs, and reported that the MIS-gate device had larger maximum drain current density and transconductance (gm) than the Schottky-gate device. The radio frequency (RF) measurement of the MIS-gate device, however, showed a relatively lower current gain cutoff frequency fT compared with that of the Schottky-gate device. In this study, C-V characterization of the MIS-gate HEMT structure demonstrated that two electron transport channels existed, one at the SiGe/Si buried channel and the other at the SiN/Si surface channel. 相似文献
Up until now there has been no direct method for detecting the electronic and magnetic structure of each atomic layer at the surface, which is an essential analysis technique for nanotechnology. For this purpose, we have developed a new method, diffraction spectroscopy, based on the photon energy dependence of the angular distribution of Auger electron emission. We have applied this method to analyze the magnetic structure of a Ni ultrathin film on a Cu(001) surface around the spin reorientation transition. Atomic-layer resolved x-ray absorption and magnetic circular dichroism spectra were obtained. Surface and interior core-level shifts and magnetic moments are determined for each atomic layer individually. 相似文献
The microstructures of a Tl0.8Pb0.2Bi0.2Sr1.6Ba0.4Ca2Cu3O9+δ/Ag tape (tape I) with Jc of 17,600 A/cm2 at 77 K and 0 T and three Tl0.8Pb0.2Bi0.2Sr1.8Ba0.2Ca2.2Cu3O9+δ/Ag tapes with Jc's of 9300 (tape II), 16,700 (tape III) and 25 200 A/cm2 (tape IV) prepared using the powder-in-tube method and an in-situ reaction method, were investigated using high-resolution transmission electron microscopy. In the tape preparation, an intermediate rolling process was incorporated during final heat-treatment for the last tape, but not for the rest of the tapes. Tl-1223 grains are in a thin plate-like shape. Tendency of directional grain-alignment increased in an order of tapes I, II, II and IV. In tape IV, Tl-1223 grains are clearly textured at least partly. In lattice defects, while stacking faults were prevalent in the former composition, dislocations and holes were frequently observed in the latter. Also impurity phases were appeared to be more abundant in the former than in the latter. The relationship between Jc and the microstructure in the tapes was explained in a term of grain-linking. 相似文献
We give explicit formulas for the dimensions and the degrees of A-discriminant varieties introduced by Gelfand, Kapranov and Zelevinsky. Our formulas can be applied also to the case where the A-discriminant varieties are higher-codimensional and their degrees are described by the geometry of the configurations A. Moreover combinatorial formulas for the Euler obstructions of general (not necessarily normal) toric varieties will be also given. 相似文献
The both enantiomers of disparlure [(7R, 8S)-(+)-epoxy-2-methyloctadecane and its (7S,8R)-(?)-isomer] were synthesized from (2R, 3R)-(+)-tartaric acid in a stereoselective manner. (+)-Disparlure was found to be biologically active. 相似文献