Wechselwirkung zwischen Farbstoffen und Polyelektrolyten, 5. Mitt. Einfluß von organischen und anorganischen Salzen auf die Metachromasie von Methylenblau

Ohne Zusammenfassung     

Beta-NMR measurement of 58Cu in Si

The β-NMR study of short-lived nucleus ⁵⁸Cu (I ^π ?=?1^?+?, T _1/2?=?3.2 s) in Si has been performed. Spin polarization of ⁵⁸Cu induced by the charge exchange reaction of ⁵⁸Ni was observed in Si at 15 K. The ⁵⁸Cu magnetic moment $|\upmu[^{58}\mbox{Cu}]| = (0.46 \pm 0.03)\upmu_{\rm N}$ deduced from the β-NMR spectrum is consistent with the previous results on the laser spectroscopy. The present result shows that the ⁵⁸Cu nucleus is promising as a new nuclear probe for the microscopic study of Cu impurities in Si.     

Neutron activation analysis of carbonate reference materials: coral (JCp-1) and giant clam (JCt-1)

Journal of Radioanalytical and Nuclear Chemistry - Two kinds of carbonate reference materials, coral (JCp-1) and giant clam (JCt-1), were subjected to neutron activation analysis (NAA) using the...     

Improved Thermal and Reusability Properties of Xylanase by Genipin Cross-Linking to Magnetic Chitosan Particles

Enzymes are gradually increasingly preferred over chemical processes, but commercial enzyme applications remain limited due to their low stability and low product recovery, so the application of an immobilization technique is required for repeated use. The aims of this work were to produce stable enzyme complexes of cross-linked xylanase on magnetic chitosan, to describe some characteristics of these complexes, and to evaluate the thermal stability of the immobilized enzyme and its reusability. A xylanase was cross-linked to magnetite particles prepared by in situ co-precipitation of iron salts in a chitosan template. The effect of temperature, pH, kinetic parameters, and reusability on free and immobilized xylanase was evaluated. Magnetization, morphology, size, structural change, and thermal behavior of immobilized enzyme were described. 1.0?±?0.1 μg of xylanase was immobilized per milligram of superparamagnetic chitosan nanoparticles via covalent bonds formed with genipin. Immobilized xylanase showed thermal, pH, and catalytic velocity improvement compared to the free enzyme and can be reused three times. Heterogeneous aggregates of 254 nm were obtained after enzyme immobilization. The immobilization protocol used in this work was successful in retaining enzyme thermal stability and could be important in using natural compounds such as Fe₃O₄@Chitosan@Xylanase in the harsh temperature condition of relevant industries.

     

Rapid crystallization of amorphous silicon utilizing a radio-frequency thermal plasma torch

The rapid crystallization of amorphous silicon utilizing the radio-frequency (rf) inductive coupling thermal plasma torch of argon is demonstrated. Highly-crystallized Si films were fabricated on thermally grown (th-)SiO₂ and textured a-Si:H:B/SnO₂/glass by adjusting a distance between the tip of the silica tube and the substrate stage and the translational velocity of the substrate stage. The crystallization was promoted efficiently from the bottom to front surface during the solidification and crystallization of liquid Si.     

Ruby ESR Over a Wide Frequency Range in the Millimeter Wave Region

The ESR of Cr³⁺ in dark ruby is measured using a high frequency ESR spectrometer with a wide frequency range which uses a gyrotron as the radiation source. For this purpose, GYROTRON FU- IV A developed at Fukui University was optimized for use in an ESR apparatus operating in the millimeter-wave range.The observed fine structure constant D for ruby is found to be D –5.728 GHz and the g-values g 1.981, g 1.982. Both the values of |D| and g are smaller than those obtained at lower frequencies by other work. Higher order terms of the spin hamiltonian are discussed in order to understand the ruby ESR results in this higher frequency range.     

Chemocavity: specific concavity in protein reserved for the binding of biologically functional small molecules

The idea that there should be a specific site on a protein for a particular functional small molecule is widespread. It is, however, usually not so easy to understand what characteristics of the site determine the binding ability of the functional small molecule. We have focused on the concurrence rate of the 20 standard amino acids at such binding sites. In order to correlate the concurrence rate and the specific binding site, we have analyzed high-quality X-ray structures of complexes between proteins and small molecules. A novel index characterizing the binding site based on the concurrency rate has been introduced. Using this index we have identified that there is a specific concavity designated as a chemocavity where a specific group of small molecules, i.e., canonical molecular group, is highly inclined to be bound. This study has demonstrated that a chemocavity is reserved for a specific canonical molecular group, and the prevalent idea has been confirmed.     

A novel route for the construction of Taxol ABC-ring framework: skeletal rearrangement approach to AB-ring and intramolecular aldol approach to C-ring

We report here on the construction of the ABC-ring framework of (±)-Taxol using an intramolecular aldol reaction as a key step. AB-ring compound 8 was converted to ketoaldehyde 25 as a precursor of an aldol reaction via introduction of oxygen-functionalities and a methoxycarbonyl group, which can be converted to a methyl group, in the proper positions of the B-ring. An aldol reaction of ketoaldehyde with LDA led to the formation of the desired product 27, which corresponds to the ABC-ring framework of (±)-Taxol.     

Determination of multiple thermal degradation mechanisms of poly(3-hydroxybutyrate)

The thermal degradation of poly(3-hydroxybutyrate) (PHB) was investigated by kinetic analyses in detail to clarify its complex degradation behavior, resulting in a finding of mixed mechanisms comprising at least a thermal random degradation with subsequent auto-accelerated transesterification, and a kinetically favored chain reaction from crotonate chain ends. The thermal degradation behavior of PHB varied with changes in time and/or temperature. From the kinetic analysis of changes in molecular weight, it was found that a non-auto-catalytic random degradation proceeding in the initial period was followed by an auto-accelerated reaction in the middle period. From the kinetic analysis of weight loss behavior, it is proposed that there are some kinetically favored scissions occurring at the chain ends, where the degradation proceeded by a 0th-order weight loss process in the middle stage. The observed 0th-order weight loss process was assumed to be an unzipping reaction occurring at ester groups neighboring the crotonate end groups.