Hiroshi Miyata

Impacts of Amplitude Modulation of RF Discharge Voltage on the Growth of Nanoparticles in Reactive Plasmas

We have investigated the effects of plasma fluctuation on the growth of nanoparticles in capacitively-coupled rf discharges with amplitude modulation (AM). Nanoparticles grow more slowly for higher AM levels, which causes the density of nanoparticles to increase by 100% and their size to decrease by 23%. The increase in the number of radicals for nucleation and nanoparticles by AM is thought to cause a decrease in the radical flux for a nanoparticle because the rate of increase in the number of radicals is smaller than that of nanoparticles. Therefore, this causes the generation of a large amount of nanoparticles with small sizes.

Antigen-specific augmentation of delayed-type hypersensitivity by immune serum factor in mice

The serum from C3H/He mice immunized with chicken erythrocytes (CRBC) in complete Freunds adjuvant contained a factor able to augment delayed-type hypersensitivity (DTH) antigen specifically, when transferred into naive syngeneic recipient mice before their sensitization with CRBC. This activity in immune serum appeared on Day 4 and reached a peak on Day 8 after immunization, and was enhanced when donor mice were treated with cyclophosphamide (CY) 2 days before immunization. The ability of recipient mice to respond to this factor was enhanced by CY treatment of these mice 4 days before being transferred. This factor could be discriminated from conventional antibodies. Production of this factor in the serum donor and the expression of its activity in transferred recipient was mediated by a T-cell subset which showed a low degree of thymus dependency in ontogenic development.

Antigen-specific augmentation factor involved in murine delayed-type footpad reaction: I. Nature of augmentation factor

A humoral factor capable of augmenting antigen-specific DTH has been found in the culture supernatant of immune spleen cells and erythrocyte antigen. In this study, a similar factor was identified in the sera of mice sensitized and elicited with heterologous erythrocytes, and the nature of this factor was investigated. Elicitation with antigen was essentially required for the production of the augmentation factor in sensitized mice. The factor showed antigen specificity and antigen-binding capacity. The activity was not assigned to immunoglobulins, as demonstrated by an absorption test with rabbit anti-mouse immunoglobulin-conjugated Sepharose. The activity was stable to heating at 56 degrees C for 30 min, to changes of pH from 3 to 10, and to treatment with trypsin or neuraminidase. The molecular weight of this factor was about 200,000 to 450,000.

Effects of amplitude modulation of rf discharge voltage on growth of nano-particles in reactive plasmas

We have first conformed the effects of amplitude modulation (AM) of rf discharge voltage on growth of nano-particles in plasma CVD. This method of AM was used to control fluctuation level of plasma parameters, and allow us to investigate the causal relationship between the nano-particle property and plasma fluctuations. We found the ratio of power of single mode to that harmonic mode is negligible small until fluctuation level of amplitude modulated rf peak-to-peak voltage becomes roughly 20 %. The growth of nano-particles during rf discharge decreased as induced plasma fluctuation level increases.

Effects of Ar addition on breakdown voltage in a Si(CH 3 ) 2 (OCH 3 ) 2 RF discharge

We present detailed measurements on breakdown voltage (V<inf>f</inf>) in a RF discharge with Si(CH<inf>3</inf>)<inf>2</inf>(OCH<inf>3</inf>)<inf>2</inf> gas diluted with Ar. When Ar concentration (P<inf>Ar</inf>) is increased, the V<inf>f</inf> gradually decreases up to P<inf>Ar</inf> = 50 %, and then is followed by a drastic decrease. The P<inf>Ar</inf> dependence of V<inf>f</inf> is well explained by a feature of the ion-induced secondary electron emission coefficient (γ) deduced from measured Paschen curves. A drastic increase in Ar ion flux with P<inf>Ar</inf> induces high emission of electrons from cathode surface, resulting in lowing V<inf>f</inf>.