Antioxidant effects of cultured wild ginseng root extracts on the male reproductive function of boars and guinea pigs.

The main objective of this study was to investigate the effects of cultured wild ginseng root extracts (cWGRE) on the sperm of boars and the reproductive system of guinea pigs. Firstly, semen collected from boars (n=10) were incubated in 38°C for 1h with xanthine and xanthine oxidase to generate ROS. The cWGRE was added to the sperm culture system to test its antioxidant effect on the boar sperm. The amount of Reactive Oxygen Species (ROS) was measured by a chemiluminescence assay using luminol. The results indicated that the addition of cWGRE to boar sperm culture inhibited xanthine and xanthine oxidase-induced ROS concentrations. Treatment with cWGRE also had a positive effect on maintaining sperm motility. Effects of cWGRE administration on vitamin C-deficient guinea pigs were further investigated. Hartley guinea pigs (n=25) at 8 weeks of age were randomly divided into five groups. With the exception of the positive control group, each group was fed vitamin C-deficient feed for 21days (d). Respective groups were also orally administered cWGRE, ginseng extract, or mixed ginsenosides for 21 days. In comparison to the control group, oral administration of cWGRE reduced (P<0.05) amount of lipid peroxidation and increased (P<0.05) both glutathione peroxidase concentrations and the trolox equivalent antioxidant capacity. In addition, administration of cWGRE induced increases (P<0.05) in body weight, testosterone concentrations, and spermatid populations. The results of the present study support our hypothesis that cWGRE has positive effects on male reproductive functions via suppression of ROS production.

Study of nanocrystalline silicon films synthesized Below 100 degrees C by catalytic chemical vapor deposition.

Nanocrystalline silicon (nc-Si) films were synthesized by catalytic chemical vapor deposition at a low substrate temperature (100 degrees C) for use as an active layer in bottom-gate thin-film transistors. The hydrogen-dilution technique was employed to increase the crystalline volume fraction of the synthesized films. The incubation layer thickness was estimated to be 5.1 nm for a hydrogen-dilution ratio, R(H) (= [H2]/[SiH4]), of 54. When R(H) was increased from 64 to 74, the deposition rate decreased from 20 to 0.5 nm/min. In order to achieve a high deposition rate and high crystallinity near the interface region, we modulated R(H) through the film thickness. We also fabricated metal-insulator-semiconductor-insulator-semiconductor diodes from multilayer structures consisting of an nc-Si layer sandwiched between two silicon nitride layers. By analyzing the capacitance-voltage characteristics of these diodes, we found that the hysteresis and rectifying behavior of these diodes were affected by the the nc-Si layer thickness.

Optical and structural properties of nanocrystalline silicon potential well structure fabricated by cat-chemical vapor deposition at 200 degrees C.

We attempted to fabricate multi-layer, thin film structures by catalytic chemical vapor deposition (Cat-CVD) at a low temperature (200 degrees C). A 5-10-nm-thick nanocrystalline silicon (nc-Si) layer was positioned asymmetrically between two silicon nitride (SINx) layers. The compositions of the SiNx layers were varied between silicon-rich and nitrogen-rich. Each layer was deposited continuously in the Cat-CVD chamber without post-annealing. High-resolution transmission electron microscopy (HRTEM) revealed that the nc-Si layer grew in columns on the surface of the bottom SiNx layer, and the columnar structure extended up to a few nanometers of the top SiNx layer. In photoluminescence (PL) spectra, the overall intensity increased with the thickness of the nc-Si layer, but the primary peak position changed more sensitively relative to the composition of the SiNx layers. Capacitance-voltage (C-V) hysteresis was observed only when 10-nm-thick nc-Si layers were inserted between the nitrogen-rich silicon nitride (NRSN) layers. Under a bias voltage of 5 V, the current in the sample with a 10-nm-thick nc-Si layer was higher by at least two orders of magnitude than that in the sample with a 5-nm-thick nc-Si layer. The I-V curve was fitted well using both the Fowler-Nordheim and the Poole-Frenkel models for electric fields of magnitudes greater than 1.1 MV/cm, thereby implying that both mechanisms contribute to the increase in the leakage current.

Thermal control of electroosmotic flow in a microchannel through temperature-dependent properties.

A numerical investigation is conducted on the electroosmotic flow and associated heat transfer in a two-dimensional microchannel. The objective of this study is to explore a new conceptual idea that is control of an electroosmotic flow by using a thermal field effect through the temperature-dependent physical properties. Two exemplary problems are examined: a flow in a microchannel with a constant vertical temperature difference between two horizontal walls and a flow in a microchannel with the wall temperatures varying horizontally in a sinusoidal manner. The results of numerical computations showed that a proper control of thermal field may be a viable means to manipulate various non-plug-like flow patterns. A constant vertical temperature difference across the channel produces a shear flow. The horizontally-varying thermal condition results in spatial variation of physical properties to generate fluctuating flow patterns. The temperature variation at the wall with alternating vertical temperature gradient induces a wavy flow.