The synthesis of plasma-polymerized tetraethoxysilane (TEOS) and hexamethyldisiloxane (HMDSO) thin films by atmospheric pressure glow (APG) discharge was investigated and the characteristics of this method were compared with those of low-pressure plasma-enhanced CVD (LPPECVD) methods. The obtained films had smooth surfaces, no pinholes and uniform thicknesses. The qualities of the films analysed by FTIR and XPS, and emission spectra during the reaction, were very similar to those observed in the LPPECVD. The relationship between the substrate temperature and the deposition rate was strongly dependent on the presence of oxygen; the deposition rate increased with increases in the substrate temperature in the presence of oxygen. This behaviour is uniquely characteristic of the APG discharge process. This is because the gas-phase reaction of the monomer decompositions is enhanced by atomic oxygen, and the reaction rates in the gas phase increase as the gas-phase temperature increases.
The reduction of copper oxide thin films by a hydrogen plasma generated by an atmospheric-pressure glow (APG) discharge was investigated. The copper oxide films were prepared by heating the sputtered copper films to C in the air (heat-formed copper oxide) or by sputtering (sputtered copper oxide). Both films were composed of . The reduction occurs first on the surface, then the interface gradually shifts from the surface into the inner region and finally the whole layer is reduced to metallic copper. This process is approximately explained by assuming that the diffusion of the atomic hydrogen in the reduced layer is the rate-deyermining step. By transmission electron microscopic (TEM) observation, a layer of 3 - 5 nm thickness composed of many microcrystals was observed along the surface of the heat-formed copper oxide. After the APG hydrogen plasma treatment, the crystal layer disappeared and the crystalline lattice was re-arranged to form large crystal Cu grains.
Background
Vascular tissues of humans and dogs contain chymase as an angiotensin II–forming enzyme. In this study, we investigated whether chymase-dependent angiotensin II formation plays a crucial role in the development of vascular proliferation in dog grafted veins.
Methods and Results
The right external jugular vein of dogs was grafted to the ipsilateral carotid artery. As a control group, the right external jugular veins in dogs that had not received grafts were used. In the chymase inhibitor–treated group, the vein was infiltrated with 10 μmol/L Suc-Val-Pro-Phe
P
(OPh)
2
and was grafted to the carotid artery. In the placebo-treated group, ACE activity in the grafted veins was significantly lower than that in the control veins up to 7 days after the operation, whereas chymase activity was increased significantly. After 7 days, the mRNA levels of collagen I, collagen III, and fibronectin, all of which are induced by an increase of angiotensin II action, were significantly increased in the grafted veins, and the intima-media ratio of the grafted veins was also increased. In the chymase inhibitor–treated group, the chymase activity in the grafted veins 7 days after the operation was suppressed to 12.1%. The elevated mRNA levels of fibronectin, collagen I, and collagen III in the grafted veins were significantly suppressed by treatment with the chymase inhibitor, and the intima-media ratio was also decreased significantly.
Conclusions
We demonstrate for the first time that chymase-dependent angiotensin II formation plays an important role in the development of vascular proliferation in the grafted veins.
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