160 resultados para JOSEFSON-NISSENZWEIG-ALPHA (JN(ALPHA)) PROPERTY

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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Hollow deoxyribonucleic acid (DNA)/poly-L-lysine (PLL) capsules were successfully fabricated through a layer-by-layer (LbL) self-assembly of DNA and PLL on porous CaCO3 microparticles, followed by removal of templates with ethylenediamine tetraacetic acid disodium salt (EDTA). The enzymatic degradation of the capsules in the presence of alpha-chymotrypsin was explored. The higher the enzyme concentration, the higher is the degradation rate of hollow capsules. in addition, glutaric dialdehyde (GA) cross-linking was found to be another way to manipulate degradation rate of hollow capsules.

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To express and product a fluorescent antioxidant holo-alpha-phycocyanin (PC) of Spirulina platensis (Sp) with His-tag (rHHPC; recombinant holo-alpha-phycocyaninof Spirulina platensis with His-tag) in 5-l bench scale. A vector harbouring two cassettes was constructed: cpcA along with cpcE-cpcF in one cassette; ho1-pcyA in the other cassette. Lyases CpcE/F of Synechocystis sp. PCC6803 (S6) could catalyse the 82 site Cys in apo-alpha-PC of Sp linking with bilin chromophores, and rHHPC was biosynthesized in Escherichia coli BL21. The constant feeding mode was adopted, and transformant reached the biomass of rHHPC up to 0.55 g l(-1) broth in 5-litre bench scale. rHHPC was purified by Ni2+ affinity column conveniently. The absorbance and the fluorescence emission spectra of rHHPC had lambda(max) at 621 and 650 nm, respectively. The IC50 values of rHHPC were 277.5 +/- 25.8 mu g ml(-1) against hydroxyl radicals and 20.8 +/- 2.2 mu g ml(-1) against peroxyl radicals. Combinational biosynthesis of rHHPC was feasible, and the constant feeding mode was adopted to produce good yields of rHHPC. Fluorescent rHHPC with several unique qualitative and quantitative features was effective on scavenging hydroxyl and peroxyl radicals. A potent antioxidant rHHPC was co-expressed, produced and characterized for nutritional and pharmacological values, which would help to develop phycobiliproteins' applications in their fluorescent and biological activities.

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Hot pressing (HP) at higher sintering temperature has been a traditional and prevalent technique for the fabrication of alpha-SiAlON. In order to prepare translucent SiAlON more easily, LiF was used as a non-oxide sintering additive to lower the sintering temperature to <= 1650 degrees C. As a result, all of the samples possessed a good hardness and fracture toughness. At the same time, the lower temperature sintered samples showed a higher optical transmittance in the range of 2.5-5.5 mu m wavelength (0.5 mm in thickness). The maximum infrared transmission reached 68% at a wavelength of 3.3 mu m. The present work shows that the sintering process has a strong effect on microstructure and property of alpha-SiAlON. To be exact, a lower sintering temperature and longer holding time can produce some fully-developed microstrcture, which is beneficial for the optical transmittance. (C) 2008 The Ceramic Society of Japan. All rights reserved.

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Theoretical researches are performed on the alpha-R2MoO6 (R = Y, Gd, Tb Dy, Ho, Er, Tm and Yb) and pyrochlore-type R2Mo2O7 (R = Y, Nd, Sm, Gd, Tb and Dy) rare earth molybdates by using chemical bond theory of dielectric description. The chemical bonding characteristics and their relationship with thermal expansion property and compressibility are explored. The calculated values of linear thermal expansion coefficient (LTEC) and bulk modulus agree well with the available experimental values. The calculations reveal that the LTECs and the bulk moduli do have linear relationship with the ionic radii of the lanthanides: the LTEC decreases from 6.80 to 6.62 10(-6)/K and the bulk modulus increases from 141 to 154 GPa when R goes in the order Gd, Tb Dy, Ho, Er, Tm, and Yb in the alpha-R2MoO6 series; while in the R2Mo2O7 series, the LTEC ranges from 6.80 to 6.61 10(-6)/K and the bulk modulus ranges from 147 to 163 GPa when R varies in the order Nd, Sm, Gd, Tb and Dy.

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Herein we report the spectroscopic, electrochemical, TEM and DLS characterizations Of C-60 supramolecular inclusion complexes with alpha-, beta- and gamma-cyclodextrins prepared using anionic C-60. The results indicate that the cyclodextrin itself has little effect on the encapsulated C-60 or on the properties of the inclusion complex. Instead, the cyclodextrin has a significant influence on the aggregation behavior of individual complex in aqueous solution, which in turn affects the property of the supramolecular complex of cyclodextrin and C-60 greatly, As the cavity dimension of cyclodextrin becomes smaller as it changes from gamma-CD to beta-CD, and finally to alpha-CD, it is observed that more aggregation occurs for the corresponding inclusion complex in aqueous solution.

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Thermodynamics of the displacive mechanism of plate-shaped phase alpha(1) was analyzed in beta'Cu-Zn alloys. It was proposed that the displacive transformation of the alpha(1) plate took place in the solute-depleted region formed in the parent phase during the incubation period. The thermodynamic analysis indicated that the driving force of alpha(1) transformation, Delta G, increased with the reduction of x(d), the solute concentration of the depleted region. And, Delta G could overcome-the transformation barrier with solute depletion to a certain degree. In addition, x(d) was higher than the equilibrium concentration in the phase diagram. Therefore, the shear formation of alpha(1) plate in the solute-depleted region was thermodynamically supported.

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A rectangular structural unit cell of a-Al2O3 is generated from its hexagonal one. For the rectangular structural crystal with a simple interatomic potential [Matsui, Mineral Mag. 58A, 571 (1994)], the relations of lattice constants to homogeneous pressure and temperature are calculated by using Monte-Carlo method at temperature 298K and 0 GPa, respectively. Both numerical results agree with experimental ones fairly well. By comparing pair distribution function, the crystal structure of a-Al2O3 has no phase transition in the range of systematic parameters. Based on the potential model, pressure dependence of isothermal bulk moduli is predicted. Under variation of general strains, which include of external and internal strains, elastic constants of a-Al2O3 in the different homogeneous load are determined. Along with increase of pressure, axial elastic constants increase appreciably, but nonaxial elastic constants are slowly changed.

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Molecular dynamics simulations have been carried our to study the atomic structure of the crystalline component of nanocrystalline alpha-iron. A two-dimensional computational block is used to simulate the consolidation process. It is found that dislocations are generated in the crystallites during consolidation when the grain size is large enough. The critical value of the grain size for dislocation generation appears to be about 9 nm. This result agrees with experiment qualitatively. AN dislocations that are preset in the original grains glide out during consolidation. It shows that dislocations in the crystallites we generated in consolidation process, but not in the original grains. Higher consolidation pressure results in more dislocations. Furthermore, new interfaces are found within crystallites. These interfaces might result from the special environment of nanomaterial. (C) 1998 Acta Metallurgica Inc.

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Molecular dynamics simulations are carried out in order to study the atomic structure of crystalline component, of nanocrystalline alpha-Fe when it is consolidated from small grains. A two-dimensional computational block is used to simulate the consolidation process. All the preset dislocations in the original grains glide out of them in the consolidation process, but new dislocations can generate when the grain size is large enough. It shows that dislocations exist in the consolidated material rather than in the original grains. Whether dislocations exist in the crystalline component of the resultant model nana-material depends upon grain size. The critical value of grain size for dislocation generation appears to be about 9 nm. This result agrees with experiments qualitatively.

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A new thermoplastic-photoconductor laser holographic recording system has been used for real-time and in situ observation of alpha-LiIO3 crystal growth. The influence of crystallization-driven convection on the concentration stratification in solution has been studied under gravity field. It is found that the stratification is closely related to the seed orientation of alpha-LiIO3 crystal. When the optical axis of crystal seed C is parallel to the gravity vector g, the velocity of the concentration stratification is two times larger than that in the case of C perpendicular-to g. It needs 40 h for the crystalline system of alpha-LiIO3 to reach stable concentration distribution (expressed as tau) at 47.6-degrees-C. The time tau is not sensitive to the seed orientation. Our results provide valuable data for designing the crystal growth experiments ia space.

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Three kinds of new nickel(II) complexes of alpha-isoxazolylazo-beta-diketones with blue-violet light absorption were synthesized. Their structures were postulated based on elemental analysis, MS and FT-IR spectra. Smooth films on K9 glass substrates were prepared using the spin-coating method. The absorption properties and thermal stability of these complexes were discussed. The static optical recording test for high density digital versatile disc-recordable (HD-DVD-R) system was also studied. (c) 2005 Elsevier B.V. All rights reserved.

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Two new azo dyes of alpha-isoxazolylazo-beta-dilcetones and their Ni(II) and Cu(II) complexes with blue-violet light wavelength were synthesized using a coupling component, different diazo components and metal (II) ions (Ni2+ and Cu2+). Based on the elemental analysis, MS spectra and FT-IR spectral analyses, azo dyes were unequivocally shown to exist as hydrazoketo and azoenol forms which were respectively obtained from the solution forms and from the solid forms. The action of sodium methoxide (NaOMe) on azo dyes in solutions converts hydrazoketo form into azoenol form, so azo dyes are coordinated with metal (II) ions as co-ligands in the azoenol forms. The solubility of all the compounds in common organic solvents such as 2,2,3,3-tetrafluoro-1-propanol (TFP) or chloroform (CHCl3) and absorption properties of spin-coating thin films were measured. The difference of absorption maxima from the complexes to their ligands was discussed. In addition, the TG analysis of the complexes was also determined, and their thermal stability was evaluated. It is found that these new metal (II) complexes had potential application for high-density digital versatile disc-recordable (HD-DVD-R) system due to their good solubility in organic solvents, reasonable and controllable absorption spectra in blue-violet light region and high thermal stability. (c) 2004 Elsevier B.V. All rights reserved.

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Crystalline beta-BBO thin films have been successfully prepared on (001)-oriented Sr2+-doped alpha-BBO substrates using liquid phase epitaxy and pulsed laser deposition techniques. The films were characterized by X-ray diffraction and X-ray rocking curve (XRC). The present results manifest that the beta-BBO thin films grown on Sr2+-doped alpha-BBO substrates have larger degree of orientation f-value and smaller XRC FWHM than the ones grown on other reported substrates. Compared with other substrates, alpha-BBO has the same UV cutoff and the similar structure to beta-BBO. These results reveal that alpha-BBO single crystal may be a promising substrate proper to the growth of beta-BBO films. (c) 2005 Elsevier B.V. All rights reserved.

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Thin films of beta barium borate have been prepared by liquid phase epitaxy on Si2+-doped alpha-BaB2O4 (alpha-BBO, the high temperature phase of barium berate) (001) and (110) substrates. The results of X-ray diffraction indicate that the films show highly (001) preferred orientation on (001)-oriented substrates while the films grown on (110) substrates are textured with (140) orientation. The crystallinity of these films was found to depend on growth temperature, rotation rate, dip time and orientation of substrate. Growth conditions were optimized to grow films with (001) orientation on (001) substrates reproducibly. The films show second harmonic generation of 400 nm light upon irradiation with 800 nm Ti: Sapphire femtosecond laser light. (c) 2005 Elsevier B.V. All rights reserved.