Antioxidant activity of Japanese pepper (Zanthoxylum piperitum DC.) fruit

Antioxidants were extracted from Japanese pepper (Zanthoxylum piperitum DC.) fruit and characterized. The antioxidant activity of the methanol extract from Japanese pepper fruit was found to be equal to that of α-tocopherol and stable under heat treatment. The main compounds that gave a significant antioxidant activity from the methanol extract were identified to be hyperoside (quercetin-3-O-galactoside) and quercitrin (quercetin-3-O-rhamnoside) as determined by HPLC, mass spectrometry, UV/Vis spectroscopy, and TLC. Radical-scavenging activities of hyperoside and quercitrin from Japanese pepper fruit were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. As a result, hyperoside and quercitrin scavenged DPPH radical strongly with IC₅₀ values of 16 and 18 μM, respectively. These observations show the presence of strong antioxidants, namely hyperoside and quercitrin in Japanese pepper fruit.     

Method to Estimate Thermal Shrinkage Behavior of Glasses

We present a method to estimate the effect of heat treatment on the shrinkage behavior of glasses. As a pre-requisite, sensitivity of the glass density as a function of glass fictive temperature is measured using the sink–float method and the slope of the relationship is used to determine the linear thermal strain proportionality factor. Evolution of the fictive temperature for different temperature–time history is measured using the infrared spectroscopy method and the results are used to estimate the structural relaxation parameters in the temperature range of interest. The overall shrinkage behavior is predicted using the linear thermal strain factor and estimated change in fictive temperature due to the thermal treatment. The predicted shrinkage behavior is observed to be in good agreement with the independent dimensional change measurements performed on large glass sheets that have undergone similar thermal treatments.     

Novel transdermal drug delivery system with polyhydroxyalkanoate and starburst polyamidoamine dendrimer

In search of an efficient transdermal drug delivery system (TDDS), a polyhydroxyalkanoate (PHA)-based system with a polyamidoamine dendrimer was examined. Tamsulosin was used as the model drug. The dendrimer was found to act as the weak enhancer. By adding the dendrimer, the dendrimer-containing PHA matrix achieved the clinically required amount of tamsulosin permeating through the skin model. This is also the first report of the application of PHA and dendrimer to the TDDS.     

Theoretical considerations on the sensitivities of electron beam resists

A theoretical study has been carried out in order to explain the sensitivities of electron beam and X-ray resists. A preliminary investigation reveals that the behavior of these resists, on irradiation by high energy radiation, may be considered to be the electronically-excited species in the polymer. To elucidate the chemical reactions in the excited states the adiabatic potential curves are calculated by the INDO/S procedure, which considers all the valence electrons and all the singly excited electronic configurations. Polyethylene and polyisobutylene were chosen as representative of crosslinkable and degradable polymers, respectively, since there is a parallelism between the beam sensitivity of resists and the effects of high energy radiation on polymers. Polyisobutylene has many antibonding curves favorable for the main chain scission in the excited states and polyethylene does not except for one improbable state. It was concluded that degradability is explainable by the ease of bond fission in the excited states; the crosslinkability is considered to be nondegradable property.     

A large discrepancy between CPM and ESR defect densities in light-soaked a-Si:H

A large discrepancy between defect densities evaluated by constant photocurrent method (CPM) and electron spin resonance (ESR) is investigated for hydrogenated amorphous silicon (a-Si:H) with various thicknesses in the process of light soaking (LS). It is shown by a computer simulation that the inhomogeneous defect distribution across the film thickness caused by a rather small penetration depth of the white light in the thick film is one of the possible origins of the discrepancy. But various other causes should also bring about the discrepancy, and the problem is still a puzzling one.     

A Microcomputer System for Spatiotemporal Visual Receptive Field Analysis

A microcomputer system was developed to measure visual spatiotemporal receptive fields. The system performs three functions: 1) generation of a binary spatiotemporal white-noise stimulus, 2) acquisition of spike discharges from retinal ganglion cells, and 3) extraction of the linear part of the spatiotemporal receptive flelds by cross correlating the input against the output. We have applied this system to the measurement of the spatiotemporal receptive fields of cat and catfish retinal ganglion cells.     

Some properties of thin aluminium nitride films formed in a glow discharge

The formation of thin AlN films and some of their electrical properties have been investigated. The films were prepared by exposing the surface of evaporated aluminium films to a glow discharge in pure nitrogen gas. It has been confirmed by transmission electron diffraction that the structure of the film is of the wurtzite type, as is that of the bulk material. It was observed that the thickness of the AlN films depends on the voltage of the glow discharge, the distance from the discharge electrode to the films and the treatment time. The electrical properties were measured in the form of a sandwich diode, i.e. Al-AlN-Au. The voltage-controlled negative resistance, which was first discovered in Al-Al₂O₃-metal diodes, has also been observed in this nitride film diode and shows very good reproducibility and stability.