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1.
To enhance chemical stability and suppress of aggregation of magnetite nanoparticles (MNPs), which are used as a support for thermoresponsive copolymer immobilization, silica coating of the MNPs is applied via the electrooxidation method. Although the resulting silica coated-MNPs also formed aggregates, the size distribution of the aggregate shifted to smaller size range. Because of that, the surface area available for copolymer immobilization increased approximately 6.7 times at maximum as compared with that of the uncoated MNPs. It contributed to the increase of the amount of the immobilized copolymer on the silica-coated MNPs, which is approximately four times larger than that on the uncoated MNPs. Fe3O4 dissolution test confirmed enhancement of chemical stability of MNPs. The thermoresponsive copolymer immobilized on the silica-coated MNPs shows the ability to recycle Cu(II) ion from Cu(II) containing solution by changing temperature with significantly shorter time than those in other thermoresponsive adsorbents in gel form. 相似文献
2.
β-FeSi2 layers have been successfully grown using a molten salt method for the first time. It was found that single phase and homogeneous β-FeSi2 layers with a columnar domain structure can be grown on FeSi substrates. The layer thickness was demonstrated to be controllable by the growth temperature and time, and was diffusion controlled. It was shown that the layers were void- and crack-free compared to similar layers grown on Fe substrates: this difference is explained in terms of Fe diffusion. This vacuum-free simple growth technique is useful for the fabrication of large area semiconductor devices at low cost. 相似文献
3.
The major outer membrane lipoprotein (Lpp) of Escherichia coli possesses serine at position 2, which is thought to function as the outer membrane sorting signal, and lysine at the C terminus, through which Lpp covalently associates with peptidoglycan. Arginine (R) is present before the C-terminal lysine in the wild-type Lpp (LppSK). By replacing serine (S) at position 2 with aspartate (D), the putative inner membrane sorting signal, and by deleting lysine (K) at the C terminus, Lpp mutants with a different residue at either position 2 (LppDK) or the C terminus (LppSR) or both (LppDR) were constructed. Expression of LppSR and LppDR little affected the growth of E. coli. In contrast, the number of viable cells immediately decreased when LppDK was expressed. Prolonged expression of LppDK inhibited separation of the inner and outer membranes by sucrose density gradient centrifugation, whereas short-term expression did not. Pulse-labeled LppDK and LppDR were localized in the inner membrane, indicating that the amino acid residue at position 2 functions as a sorting signal for the membrane localization of Lpp. LppDK accumulated in the inner membrane covalently associated with the peptidoglycan and thus prevented the separation of the two membranes. Globomycin, an inhibitor of lipoprotein-specific signal peptidase II, was lethal for E. coli only when Lpp possessed the C-terminal lysine. Taken together, these results indicate that the inner membrane accumulation of Lpp per se is not lethal for E. coli. Instead, a covalent linkage between the inner membrane Lpp having the C-terminal lysine and the peptidoglycan is lethal for E. coli, presumably due to the disruption of the cell surface integrity. 相似文献
4.
C Ishihara K Ochiai M Kagami H Takashahi G Matsuyama S Yoshida H Tomioka N Koya 《Canadian Metallurgical Quarterly》1997,110(3):524-529
In order to determine whether or not IFN-gammaR is associated with regulatory mechanisms on human eosinophil function, we examined the expression of functional IFN-gammaR on human peripheral eosinophils. In this study, peripheral blood eosinophils were obtained from seven normal controls and 12 patients (bronchial asthma, n = 9, and hypereosinophilic syndrome (HES), n = 3), and the purity of eosinophils was 97.11 +/- 2.31%, n = 19. We first showed that anti-IFN-gammaR alpha-chain MoAb reacted with all tested eosinophils of both normal controls and patients by flow cytometry analysis. We also showed expression of mRNA for the alpha-chain of IFN-gammaR in all purified eosinophils of six individuals. Further, to characterize IFN-gammaR on eosinophils, we did binding experiments with 125I-IFN-gamma on purified peripheral eosinophils. The linear Scatchard plot indicated a single type of high-affinity binding sites (dissociation constant (Kd) = 3.89-4.95 x 10(-10) M, numbers of binding sites = 183-233/cell, n = 3). To determine whether IFN-gammaR on eosinophils is functional, we examined surface eosinophilic cationic protein (ECP) and CD69 induction after IFN-gammaR ligation with recombinant human IFN-gamma (rhIFN-gamma) on eosinophils by flow cytometry. rhIFN-gamma stimulation significantly induced both ECP and CD69 expression on the 2-18 h-cultured eosinophils in a dose-dependent manner. Further, the effects of rhIFN-gamma stimulation were significantly blocked by both a neutralizing anti-IFN-gamma MoAb and a blocking anti-IFN-gammaR MoAb. These results suggest that human peripheral eosinophils express functional IFN-gammaR. 相似文献
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Several members of the apoptosis-regulating Bcl-2 family of proteins can homo- or heterodimerize with each other at neutral pH and can also form ion channels in synthetic membranes at low pH. The effects of low pH on dimerization among these proteins, however, have not heretofore been examined. Surface plasmon resonance was used to examine the kinetics of dimerization as a function of pH between the anti-apoptotic protein Bcl-XL (applied in the mobile phase) and three other members of the Bcl-2 family: Bcl-2, Bax, and Bid (immobilized on biosensor chips). In all cases, the relative affinity of dimerization was substantially increased at pH 4.0 compared to pH 7.0-7.4, ranging from a approximately 10-fold enhancement for Bcl-XL/Bcl-XL homodimers to >60-fold for Bcl-XL/Bid heterodimers. Comparison of the apparent association (ka) and dissociation (kd) rates at neutral and acidic pH revealed that the major contributor to increased affinity at low pH was a decreased rate of dimer dissociation. Thus, low pH stabilizes homo- and heterodimeric complexes comprised of Bcl-XL and these other Bcl-2 family proteins. At pH 4.0, the circular dichroism spectra of Bcl-XL and Bax were essentially unchanged relative to pH 7.0-7.4, indicating a complete retention of alpha-helical secondary structure at low pH and excluding gross denaturation of the proteins. Size-exclusion chromatography and bisANS (4,4'-dianilino-1, 1'-binaphthyl-5,5'-disulfonic acid) labeling studies provided indirect evidence that Bcl-XL may undergo conformational changes at low pH. The findings are discussed with respect to the mechanisms of ion-channel formation by Bcl-2 family proteins and the putative molten globule state that has been proposed for these and structurally similar proteins. 相似文献
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Summary Three pairs of polyimide/polyimide blends (50/50 wt%) with different molecular structures were prepared by two ways, i.e. mixing of the polyamic acid precursors with subsequent imidization, and direct solution mixing of the polyimides. The blends were studied with DMA technique. The results obtained show that all the blends prepared with these two different ways are miscible, as there existed only one glass transition temperature (Tg) for all the blends. It is suggested that the miscibility of these polyimide/polyimide blends is a result of the strong inter-molecular charge-transfer interaction between the chains of their components. 相似文献
10.
本文研究了硅胶纱布膜的制备方法和治疗效果。在增生性瘢痕的治疗中,硅凝胶能较快地软化和减轻瘢痕,其治疗时间要比加压疗法短。目前,对硅凝胶的作用机理尚未完全明了,但一般认为水化和封闭是治疗作用的主要基础 相似文献