Numerical enclosure for each eigenvalue in generalized eigenvalue problem

An algorithm for enclosing all eigenvalues in generalized eigenvalue problem Ax=λBx is proposed. This algorithm is applicable even if A∈C^n×n is not Hermitian and/or B∈C^n×n is not Hermitian positive definite, and supplies nerror bounds while the algorithm previously developed by the author supplies a single error bound. It is proved that the error bounds obtained by the proposed algorithm are equal or smaller than that by the previous algorithm. Computational cost for the proposed algorithm is similar to that for the previous algorithm. Numerical results show the property of the proposed algorithm.     

Oxide-ion conductivity of (Ba1−xLax)2In2O5+x system based on brownmillerite structure

(Ba_1−xLa_x)₂In₂O_5+x, whose end member is Ba₂In₂O₅, is an oxygen-deficient perovskite oxide showing high oxide-ion conductivity. In order to clarify the reason why the high oxide ion conductivity appeared in this system, the electrical conductivity was measured as a function of temperature and La content. With an increasing La content, the discontinuous jump of ion conductivity in the Arrhenius plot, which is related to the disordering of the oxygen vacancies, disappeared for the sample with x0.2. Above x=0.12, the ion conductivity linearly increased with La content, while the activation energy remained constant with respect to the La content. Moreover, the conductivity for x=0.6 was 0.042 (S/cm) at 1073 K, which exceeded that of 8 mol% yttria-stabilized zirconia. The higher oxide-ion conductivity of this system could be dominated by the amount of mobile oxygen ions.     

Hydrogen Effects for Propylene Polymerization with Ultra Low TiCl3 Loading MgCl2-Supported Catalyst

Hydrogen effects for propylene polymerization were investigated with ultra low TiCl₃ loading MgCl₂-supported catalysts in which the electric states of Ti species can be almost uniform. Hydrogen did not affect the catalyst activity, while the efficiency of hydrogen as a chain transfer agent was found to depend on the Ti content of the catalyst and the stereospecificity of the polymerization sites: Hydrogen was effective for isospecific sites independent of Ti contents, but inert for aspecific sites only at the extremely low Ti content. These results were explained within the island model, where isospecific sites may be located in the islands with other Ti species in their surroundings acting, as a steric hindrance for isospecific polymerization and as hydrogen dissociation sites after deactivation. Most of the aspecific sites should be isolated only at the extremely low Ti content. These isolated sites have no other Ti species in their surroundings, i.e. no hydrogen dissociation sites, and are inert to hydrogen.     

A new application of statistical moment theory to evaluate the swelling behavior of thermo-responsive gels

The loosely cross-linked poly(acryloyl-L -proline methyl ester) gel, which is known as one of the typical thermo-responsive gels, shows a volume transition around approximately 14°C in pure water. This volume transition is shifted to higher temperature by treatment in aqueous sodium dodecyl sulfate (SDS). The analysis of the swelling-temperature curve (frequency distribution) was performed according to a moment analysis, in which the area under the swelling-temperature curve (AUC), mean swelling transition temperature (MSTT) and variance of swelling transition temperature (VSTT) were calculated. It is shown that the apparent volume transition temperature can be estimated from MSTT and that VSTT can be used to characterize the shape of the corresponding curves.     

Synthesis of a biodegradable polymeric supramolecular assembly for drug delivery

A novel design of a biodegradable carrier for drug delivery was established by constructing a supramolecular assembly of drugs and polymer backbones without any covalent bonds. A biodegradable polyrotaxane was synthesized in which α-cyclodextrins (α-CDs) as drug carriers were threaded onto poly(ethylene glycol) chains which then were capped at each chain end by L -phenylalanine via peptide linkages. The release of α-CDs was observed only when the terminal peptide linkages were degraded.     

1H NMR spectral analysis of physalin A,a 13,14-seco-16,24-cyclosteroid,based on crystal structure of (25R)-2,3,25,27-tetrahydrophysalin a dimethanol solvate

(25R)-2,3,25,27-Tetrahydrophysalin A dimethanol solvate, C₃₀H₄₂O₁₂, a derivative of 13,14-seco-16,24-cyclosteroid physalin A, crystallizes in the orthorhombic space groupP2₁2₁2₁, witha=15.486(5),b=14.794(4), 12.248(6) Å andZ=4. The crystal structure has been solved by direct methods, and refined to an R-value of 0.053 for 2345 observed reflections.¹H NMR spectral data of physalin A and its hydrogenated derivatives measured in dimethylsulfoxide-d₆ solutions have been elucidated, based on the crystal structure of the tetrahydrophysalin A, enabling the assignment of all the proton signals of physalin A. The-proton of C(11)-methylene has been shown to resonate at remarkably higher field due to anisotropic shielding effect of carbonyl group at C(15).     

A Supramolecular Hydrogel Based on Polyglycerol Dendrimer‐Specific Amino Group Recognition

Dendrimer‐based supramolecular hydrogels have gained attention in biomedical fields. While biocompatible dendrimers were used to prepare hydrogels via physical and/or chemical crosslinking, smart functions such as pH and molecular control remain undeveloped. Here, we present polyglycerol dendrimer‐based supramolecular hydrogel formation induced by a specific interaction between the polyglycerol dendrimer and an amino group of glycol chitosan. Gelation was achieved by mixing the two aqueous solutions. Hydrogel formation was controlled by varying the polyglycerol dendrimer generation. The hydrogel showed pH‐dependent swelling; strongly acidic conditions induced degradation via dissociation of the specific interaction. It also showed unique l ‐arginine‐responsive degradation capability due to competitive exchange of the amino groups of glycol chitosan and l ‐arginine. These polyglycerol dendrimer‐based supramolecular characteristics allow multimodal application in smart biomaterials.