In situ observations of domain wall motion in Mn–Zn and Ni–Zn ferrites by Lorentz microscopy and electron holography

Domain wall motion in Mn–Zn and Ni–Zn ferrites with applied magnetic fields is investigated by in situ observations with Lorentz microscopy and electron holography. It is found that both Mn–Zn and Ni–Zn ferrites have a mean grain size of approximately 10 μm and several pores with sizes ranging from 0.2 to 1.1 μm. In situ observations by Lorentz microscopy with an applied magnetic field reveals that in Mn–Zn ferrite, the domain walls move easily across the grain boundary, while in Ni–Zn ferrite, the domain walls move along the grain boundary but are pinned at the grain boundary and pores. From in situ observations of Ni–Zn ferrite by electron holography, it is clarified that domain wall pinning at the grain boundary retards a sensitive increase in magnetic flux parallel to the applied field direction, which is considered to result in high hysteresis loss.     

Electrical properties and memory effect in the field effect transistor based on organic ferroelectric insulator and pentacene

We have fabricated a field effect transistor (FET) based on an organic ferroelectric insulator and molecular conductor, and investigated the electrical properties and memory effects on the PEN-FET. We have observed a drastic change in the drain current at around the coercive electric fieldE _c of the organic ferroelectric insulator in not only a FET (PEN-FET) based on a pentacene (PEN) film but also a FET (IPEN-FET) based on an iodine doped PEN film. The magnitude of the change of the drain current for the IPEN-FET is 200 times larger than that for the PEN-FET. It is expected from these results that the PEN-FET (especially the IPEN-FET) is an improvement in such devices, since it operates at a low gate electric field accompanied by the appearance of the spontaneous polarization in the organic ferroelectric insulator. In addition, we have found that the drain current for the PEN-FET does not return to the initial drain current ofE _G =0 V/cm for more than one week, even if the gate electric field is changed to 0 V/cm from 500 V/cm(>E _c ). From these results, it is suggested that the PEN-FET becomes a memory device.     

Fluorescence labeling of oligosaccharides useful in the determination of molecular interactions.

A simple method to label oligosaccharides with a multifunctional fluorescent group was developed. Oligosaccharides were quantitatively labeled at their reducing termini with pyrene butanoic acid hydrazide. The pyrene-labeled oligosaccharides were successfully applied to fluorescence polarization measurements and ELISA at picomole quantity, which was not previously reached by other procedures. This labeling method should prove to be useful in a variety of aspects in glycobiology.     

Unsaturated bond existing in tetrafluoroethylene-propylene-vinylidene fluoride terpolymer

Infrared and nuclear magnetic resonance (NMR) spectroscopies have been applied for quantitative comparison on unsaturated bonds in tetrafluoroethylene (TFE)-propylene (P)-vinylidene fluoride (VdF) terpolymers. These spectroscopies have led to consistent results while they are based on completely different principles. It is shown that the absolute concentration can be evaluated from NMR measurements. The behavior of unsaturation has been discussed in terms of after-treatment such as wet and dry treatments. The result obtained here can give the important information to improve the performance of fluoroelastomer based on TFE-P-VdF terpolymers.     

Solid-State polymerization of the binary mixture of methacrylate and liquid-crystalline compound by electron beam

Solid-state polymerization of a binary mixture of nonliquid-crystalline monomer and liquidcrystalline compound was carried out using electron beam. The monomers were benzoic acid containing 4-[ω-(meth)acryloyloxyalkyloxy] benzoic acids, in which the alkylene spacer was ethylene, hexamethylene, or undecamethylene. The conversion yield of monomer to polymer to a large extent increased with increasing content of a liquid-crystalline compound with a terminal carboxylic group, such as 4-n-alkyloxybenzoic acid, while the addition of a liquid-crystalline compound without terminal carboxylic group did not affect polymerization of the monomer. Phase diagrams of the mixture of monomer and liquid-crystalline compound were examined using cross-polarizing microscopy and differential scanning calorimetry (DSC). All mixtures of monomer and 4-n-alkyloxybenzoic acid or liquid-crystalline compound without terminal carboxylic group showed liquid-crystallinity in a broad composition range. It was concluded that liquid-crystalline compounds with terminal carboxylic acid may form hydrogen bondings with methacrylate or acrylate monomer having terminal carboxylic acid which enhance polymerizability of the mixture. The stereoregularity of polymers determined by NMR depended on increasing irradiation dose and temperature rather than the content of the added liquid-crystalline 4-n-decanoxybenzoic acid.     

High-speed counter-current chromatography of apple procyanidins

Apple procyanidins were separated by high-speed counter-current chromatography using a type-J multilayer coil planet centrifuge. Several two-phase solvent systems with a wide range of hydrophobicities from a non-polar hexane system to polar n-butanol systems were evaluated their performance in terms of the partition coefficient and the retention of the phase. The best separation of procyanidins B and C was achieved with a two-phase solvent system composed of n-butanol-methyl tert.-butyl ether-acetonitrile-0.1% trifluoroacetic acid (2:4:3:8) using the lower phase as a mobile at a flow-rate of 1.0 ml/min.     

Heteroatom-guided torquoselective olefination of alpha-oxy and alpha-amino ketones via ynolates

Ynolates were found to react with alpha-alkoxy-, alpha-siloxy-, and alpha-aryloxyketones at room temperature to afford tetrasubstituted olefins with high Z selectivity. Since the geometrical selectivity was determined in the ring opening of the beta-lactone enolate intermediates, the torquoselectivity was controlled by the ethereal oxygen atoms. From experimental and theoretical studies, the high Z selectivity is induced by orbital and steric interactions rather than by chelation. In a similar manner, alpha-dialkylamino ketones provided olefins with excellent Z selectivity. These products can be easily converted into multisubstituted butenolides and gamma-butyrolactams in good yield.     

Evaluation of the disintegration time of rapidly disintegrating tablets via a novel method utilizing a CCD camera

Many kinds of rapidly disintegrating or oral disintegrating tablets (RDT) have been developed to improve the ease of tablet administration, especially for elderly and pediatric patients. In these cases, knowledge regarding disintegration behavior appears important with respect to the development of such a novel tablet. Ordinary disintegration testing, such as the Japanese Pharmacopoeia (JP) method, faces limitations with respect to the evaluation of rapid disintegration due to strong agitation. Therefore, we have developed a novel apparatus and method to determine the dissolution of the RDT. The novel device consists of a disintegrating bath and CCD camera interfaced with a personal computer equipped with motion capture and image analysis software. A newly developed RDT containing various types of binder was evaluated with this protocol. In this method, disintegration occurs in a mildly agitated medium, which allows differentiation of minor distinctions among RDTs of different formulations. Simultaneously, we were also able to detect qualitative information, i.e., morphological changes in the tablet during disintegration. This method is useful for the evaluation of the disintegration of RDT during pharmaceutical development, and also for quality control during production.     

Effect of hydrophobic amino acids on the conformational change of decapeptides in micellar environments

A series of peptides containing various hydrophobic amino acids [methionine (Met), leucine (Leu), norleucine (Nle), phenylalanine (Phe), 2-aminooctanoic acid (Aoc), and 2-aminodecanoic acid (Ade)] were synthesized and their conformations were studied using circular dichroism (CD) spectroscopy in different solvents such as water, methanol, and aqueous solution of ammonium tetradecanesulfonate. Peptides containing hydrophobic amino acids with linear side chains formed -sheets in water and methanol. Electrostatic interaction between the charged side chain (lysine) and a micelle consisting of an anionic surfactant, ammonium tetradecanesulfonate, is necessary for the formation of -helices in micellar environments. The conformational transition from -helix to -sheet structure required moderate hydrophobicity and linear side chains. This conformational transition depended on the surfactant concentration.     

Characterization of low molecular weight organic acids from beech wood treated in supercritical water

Japanese beech (Fagus crenata Blume), its cell wall components, and model compounds were treated by supercritical water (380°C, 100 MPa) for 5 s using a batch-type reactor to investigate the production behavior of low molecular weight organic acids. It was found that cellulose and hemicellulose were decomposed to formic acid, pyruvic acid, glycolic acid, acetic acid, and lactic acid, whereas lignin was barely decomposed to such organic acids under the given conditions. However, after prolonged treatment (380°C, 100 MPa, 4 min) of lignin, some organic acids were recovered owing perhaps to the decomposition of the propyl side chain of lignin. It was additionally revealed that the predominant organic acid recovered was acetic acid, which might be derived from the acetyl group of hemicellulose in Japanese beech.