Comblike polymer electrolyte with main chain glass transition near room temperature

A new amorphous comblike polymer (CBP) based on methylvinyl ether/maleic anhydride altering copolymer backbone and on oligooxyethylene side chain was synthesized. The dynamic mechanical properties of CBP and its Li salt complexes were investigated by means of DDV-11-EA type viscoelastic spectrometry. Results showed that there were two glass transitions (alpha-transition and beta-transition) in the temperature range from -100 to 100 degrees C. The beta-transition was assigned to oligo-PEO side chains and the temperature of beta-transition increases with increasing Li salt content. The alpha-transition was assigned to the main chain of CBP. The temperature of the alpha-transition (T-alpha) is also dependent upon the Li-salt content, but not monotonic. The value of T-alpha lies between 30-45 degrees C in the Li salt concentration range studied, near room temperature. It was found that the CBP-Li salt complexes showed an unusual dependence of ionic conductivity on Li salt content. There are two peaks in the plot of the ionic conductivity vs. Li salt concentration, which has been ascribed to the movability of the CBP main chain at ambient temperature. The temperature dependence bf the ionic conductivity indicated that the Arrhenius relationship was not obeyed, and the plot of log sigma against 1/(T - T-0) showed the unusual dual VTF behavior when using side chain glass transition temperature (T-beta) as T-0.

SOME NEWER CONCEPTS OF ETHYLENE ALPHA-OLEFIN COPOLYMERIZATION ON HETEROGENEOUS ZIEGLER-NATTA CATALYSTS

Unsteady diffusion kinetic, recently advanced by this laboratory, is applied to the examination of some polymerization and molecular chain structure problems. Hitherto deemed "anomalous" phenomena, such as the faster rate of copolymerization of ethylene/alpha-olefin than the homopolymerization of ethylene and the enrichment in the incorporation of a higher alpha-olefin in its copolymerization with ethylene by a lower alpha-olefin, are reasonably explained by unsteady diffusion of monomers. Molecular chain structure of copolymers, such as compositional heterogeneity and its dependence on comonomer incorporation originates from the difference in diffusion coefficients of the monomers. A copolymer composition equation taking into consideration the unsteady diffusion was developed. In cases where simulated curves were compared with experimental curves, good agreements were found.

Molecular cloning and characterization of a putative lipopolysaccharide-induced TNF-alpha factor (LITAF) gene homologue from Zhikong scallop Chlamys farreri

LPS-induced TNF-alpha factor (LITAF) is a novel transcriptional factor that was first discovered in LPS-stimulated human macrophage cell line THP-1. LITAF can bind to TNF-a promoter to regulate its expression. The first scallop LITAF (named as CfLITAF) was cloned from Zhikong scallop Chlamys farreri by Expressed Sequence Tag (EST) and Polymerase Chain Reaction (PCR) techniques. The cDNA of CfLITAF was of 1240 bp and consisted of a 5' untranslated region (UTR) of 112 bp, a 3' UTR of 678 bp and an open reading frame (ORF) of 450 bp encoding a polypeptide of 149 amino acids with an estimated molecular mass of 16.08 kDa and theoretical isoelectric point of 6.77. A typical conserved LITAF-domain was identified in CfLITAF by SMART analysis. Homology analysis of the deduced amino acid sequence of CfLITAF with other known sequences by using the BLAST program revealed that CfLITAF was homologous to the LITAF from human and rat (Identity = 46%), cattle, horse, mouse and chicken (Identity = 48%), western clawed frog (Identity = 42%), and zebrafish (Identity = 50%). The mRNA expression of CfLITAF in different tissues including haemocytes, muscle, mantle, heart, gill and gonad, and the temporal expression in haemocytes challenged by LPS or peptidoglycan (PGN) were measured by Real-time RT-PCR. CfLITAF mRNA transcripts could be detected in all tissues examined and be up-regulated in haemocytes after LPS challenge. No significant changes were observed after PGN stimulation. All these data indicated the existence of LITAF in scallop and also provided clue on the presence of TNF-alpha-like molecules in invertebrates. (C) 2007 Elsevier Ltd. All rights reserved.

Thermodynamics of the displacive mechanism of alpha(1) transformation in a beta

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.

Pressure and thermal effects on elastic properties of single crystal alpha-Al2O3 from Monte-Carlo simulation

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.

Molecular dynamics studies on dislocations in crystallites of nanocrystalline alpha-iron

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.

Dislocations in the crystallites of nanocrystalline alpha-Fe - A molecular dynamics study

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.

A study on stratification of concentration in crystal-growth of alpha-liio3 by holographic-interferometry

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.

Synthesis of nickel(II) complexes of alpha-isoxazolylazo-beta-diketones and their absorption of spin-coating films and thermal properties for HD-DVD-R

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.

Spectroscopic and thermal properties of short wavelength metal (II) complexes containing alpha-isoxazolylazo-beta-diketones as co-ligands

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.

Growth of beta barium borate (beta-BaB2O4) thin films on alpha barium borate (alpha-BaB2O4) substrates

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.

Preparation of crystalline beta barium borate thin films on Sr2+-doped alpha barium borate substrates by liquid phase epitaxy

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.

Fabrication of beta-BaB2O4 layers on (001) Sr2+-doped alpha-BaB2O4 by vapor transport equilibration (VTE)

Crystalline beta-BBO layers have been successfully prepared on (0 0 1)-oriented Sr2+-doped alpha-BBO substrates using vapor transport equilibration technique. The layers were characterized by X-ray diffraction, X-ray rocking curve and transmission spectra. The present results manifest that the VTE treatment time and powder ratio are important factors on the preparation of beta-BBO layers. beta-BBO layers with a highly (0 0 l) preferred orientation were obtained according to XRD profiles. The full width at half-maximum of the rocking curve for the layer is as low as about 1000 in., which shows the high crystallinity of the layer. These results reveal the possibility of fabricating beta-BBO (0 0 1) layers on (0 0 1)-oriented Sr2+-doped alpha-BBO substrates by VTE. (C) 2006 Elsevier Ltd. All rights reserved.

Edge-defined, film-fed growth (EFG) technique for the preparation of alpha-Al2O3 : C crystal with highly sensitive thermoluminescence response

In this work, alpha-Al2O3:C, a highly sensitive thermoluminescence dosimetry crystal, was grown by the EFG method in which a graphite heating unit and shield acted as the carbon source during the growth process. The optical, luminescent properties and dosimetric characteristics of the crystal were investigated. The as-grown crystal shows a single glow peak at 536 K, which is associated with Cr3+ ions. After annealing in H-2 at 1673 K for 80 h, the crystal shows a single glow peak at 460 K and a blue emission band at 415 nm. The thermoluminescent response of the annealed crystal shows linear-sublinear-saturation characteristics in the dose range from 5 x 10(-6) to 100 Gy.

Growth of highly sensitive thermoluminescent crystal alpha-Al2O3 : C by the temperature gradient technique

In this work, an alpha-Al2O3:C crystal with highly sensitive thermoluminescence was directly grown by the temperature gradient technique (TGT) using Al2O3 and graphite powders as raw materials. The optical and luminescent properties and the dosimetric characteristics of the crystal were investigated. An as-grown alpha-Al2O3:C crystal shows a single glow peak at 462 K and a blue emission peak at 415 nm. The thermoluminescence (TL) response of the crystal shows a linear-sublinear-saturation characteristic. In the dose range from 5 x 10(-6) to 10Gy, the alpha-Al2O3:C crystal shows excellent linearity, and saturation was observed at about 30Gy. The sensitivity of the crystal decreases as the heating rate increases. (c) 2008 Elsevier B.V. All rights reserved.