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Antioxidant effects of carotenoids in a model pigment-protein complex

100%

Fiedor J., Sulikowska A., Orzechowska A., Fiedor L., Burda K.

Acta Biochimica Polonica

2012

vol. 59

issue 1

61-64

The effect of carotenoids on stability of model photosynthetic pigment-protein complexes subjected to chemical oxidation with hydrogen peroxide or potassium ferricyanide was investigated. The oxidation of carotenoid-less and carotenoid-containing complexes was conducted in the presence or absence of ascorbic acid. The progress of the reactions was monitored by use of absorption and fluorescence spectroscopy. Our results show that carotenoids may significantly enhance the stability of photosynthetic complexes against oxidation and their protective (antioxidant) effect depends on the type of the oxidant.

On formation of thin SiO2/a-Si:H interface when biased oxidized semiconductor surface interacts with plasma or liquid solution

88%

Pinčík E., Kobayashi H., Takahashi M., Brunner R., Jurečka S., Rusnák J.

In this paper we present the results of research into a relation(s) between the bias voltage of an oxide/a-Si:H/c-Si sample during formation of very-thin and thin oxides and the resulting distribution of oxide/semiconductor interface states in the a-Si:H band gap. Two oxygen plasma sources were used for the first time in our laboratories for formation of oxide layers on a-Si:H: i) inductively coupled plasma in connection with its application at plasma anodic oxidation; ii) rf plasma as the source of positive oxygen ions for the plasma immersion ion implantation process. The oxide growth on a-Si:H during plasma anodization is also simply described theoretically. Properties of plasmatic structures are compared to ones treated by chemical oxidation that uses 68 wt% nitric acid aqueous solutions. We have confirmed that three parameters of the oxide growth process - kinetic energy of interacting particles, UV-VIS-NIR light emitted by plasma sources, and bias of the samples - determine the distribution of defect states at both the oxide/a-Si:H interface and the volume of the a-Si:H layer, respectively. Additionally, a bias of the sample applied during the oxide growth process has a similar impact on the distribution of defect states as it can be observed during the bias-annealing of similar MOS structure outside of the plasma reactor.

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1 Acta Biochimica Polonica

1 Open Physics

1 2012

1 2007

1 Brunner R.

1 Burda K.

1 Fiedor J.

1 Fiedor L.

1 Jurečka S.

1 Kobayashi H.

1 Orzechowska A.

1 Pinčík E.

1 Rusnák J.

1 Sulikowska A.

1 Takahashi M.

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Antioxidant effects of carotenoids in a model pigment-protein complex

On formation of thin SiO2/a-Si:H interface when biased oxidized semiconductor surface interacts with plasma or liquid solution