The effect of ultrafine WO3 nanoparticles on the organization of thylakoids enriched in photosystem II and energy transfer in photosystem II complexes.

In this work, a new approach to construct self-assembled hybrid systems based on natural PSII-enriched thylakoid membranes (PSII BBY) is demonstrated. Superfine m-WO3 NPs (≈1-2 nm) are introduced into PSII BBY. Transmission electron microscopy (TEM) measurements showed that even the highest concentrations of NPs used did not degrade the PSII BBY membranes. Using atomic force microscopy (AFM), it is shown that the organization of PSII BBY depends strongly on the concentration of NPs applied. This proved that the superfine NPs can easily penetrate the thylakoid membrane and interact with its components. These changes are also related to the modified energy transfer between the external light-harvesting antennas and the PSII reaction center, shown by absorption and fluorescence experiments. The biohybrid system shows stability at pH 6.5, the native operating environment of PSII, so a high rate of O2 evolution is expected. In addition, the light-induced water-splitting process can be further stimulated by the direct interaction of superfine WO3 NPs with the donor and acceptor sides of PSII. The water-splitting activity and stability of this colloidal system are under investigation. RESEARCH HIGHLIGHTS: The phenomenon of the self-organization of a biohybrid system composed of thylakoid membranes enriched in photosystem II and superfine WO3 nanoparticles is studied using AFM and TEM. A strong dependence of the organization of PSII complexes within PSII BBY membranes on the concentration of NPs applied is observed. This observation turns out to be crucial to understand the complexity of the mechanism of the action of WO3 NPs on modifications of energy transfer from external antenna complexes to the PSII reaction center.

Strong interfacial Dzyaloshinskii-Moriya induced in Co due to contact with NiO.

The magnetic properties of NiO/Co/Pt as a function of Co layer thickness were investigated by polar magneto-optical Kerr effect (PMOKE) (magnetometry and microscopy) and Brillouin Light Scattering (BLS) spectroscopy. PMOKE measurements revealed strong surface anisotropy (1.8 mJ/m2) favoring perpendicular magnetic anisotropy and asymmetric domain wall propagation explained by anticlockwise chirality. BLS measurements show that this chirality is induced by strong interfacial Dzyaloshinskii-Moriya interaction (+ 2.0 pJ/m). This is one of the highest values reported so far for Co layers surrounded by different layers. The observed chirality is opposite to what has been found in Co/oxide interfaces. These results and data published earlier, indicate that the strength of interfacial Dzyaloshinskii-Moriya interaction increases with the amount of stoichiometric NiO. Therefore, this work shows that NiO is the source of the interfacial Dzyaloshinskii-Moriya interaction.

Demonstrating the steady performance of iron oxide composites over 2000 cycles at fast charge-rates for Li-ion batteries.

The feasibility of using iron oxides as negative electrode materials for safe high-power Li-ion batteries is demonstrated by the carbon-coated FeOx/CNT composite synthesized by controlled pyrolysis of ferrocene, which delivered a specific capacity retention of 84% (445 mA h g(-1)) after 2000 cycles at 2000 mA g(-1) (4C).

Aging effects of anatase TiO2 nanoparticles in Li-ion batteries.

Anatase TiO2 nanoparticles with a diameter of 5 nm have been investigated as a negative intercalation electrode material for Li-ion batteries. The focus was on the stability upon cycling within four different potential ranges, namely from 1.5, 1.2, 1.0 and 0.7 V vs. Li/Li(+) as the lower potential limit to 3.0 V vs. Li/Li(+) as the upper potential limit. While a lower cut-off potential allows for a higher amount of charge stored, the irreversible processes induce a faster fading of the specific charge. Galvanostatic cycling (GC), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) experiments suggest that SEI formation has a negligible contribution to the irreversible processes. It appears more plausible that an irreversible degradation of the bulk phase occurs, leading to a decrease in the amount of active sites. Moreover, it has been observed that this degradation appears as an anodic shift of the thermodynamic potential of (de-)intercalation of Li-ions in the TiO2 structure. The shift is caused by a change in the activity of Li-ions in the solid phase, which is driven by changes in the ionic atmosphere of the crystal.

Oxygen on an Fe monolayer on W(110): From chemisorption to oxidation.

The adsorption of oxygen on a pseudomorphic iron monolayer deposited on a W(110) surface was studied experimentally and theoretically. Standard surface characterization methods, such as Auger electron spectroscopy and low energy electron diffraction, and specific nuclear methods, such as conversion electron Mössbauer spectroscopy (CEMS) and nuclear resonant scattering of synchrotron radiation, combined with theoretical calculations based on the density functional theory allowed us to determine the structure of the oxygen adsorbate and the electronic properties of iron atoms with different oxygen coordinations. The oxygen-(3 × 2) structure on the iron monolayer was recognized and was interpreted to be a state with oxygen chemisorbed on the non-reconstructed surface with modest electron transfer from iron to oxygen. A transition from chemisorbed oxygen to the onset of Fe-oxidation is revealed by distinct changes in the CEMS spectra.

Modification of bovine interferon and tumor necrosis factor production by lead in vivo and in vitro.

Dairy cows were treated orally with lead 5 mg/kg of body weight every day during 4 weeks. Blood was taken before treatment and 3, 7, 14, 21, 28 days after first dose of lead and plasma interferon (IFN) and tumor necrosis factor (TNF) titers were assayed. The ability of cow's blood leukocytes to ex vivo production of IFN and TNF was also examined. Lead exposure caused a significant increase in the plasma level of both cytokines examined. Ex vivo blood leukocytes of lead-treated cows exhibited normal, comparable to controls, production of TNF, but decreased production of virus-induced IFN. When blood leukocytes of control cows, not treated with lead were induced in vitro to produce IFN and TNF in the presence of different concentrations of lead, a significant reduction in IFN titers was observed, but enhanced production of TNF. Such differentiated effect of lead on IFN and TNF production suggests that lead can influence the immunity by disregulation of the cytokine network.

Effect of exogenous hormones on estrogen and progesterone release from cultured rat granulosa cells from various stages of estrous cycle.

Progesterone and estrogen levels in the culture media of granulosa cells isolated from rat ovarian follicles in all stages of estrous cycle were estimated using RIA, with special regard to hormone levels in proestrus. In control cultures the peak of progesterone release occurred at 20.00 h in proestrus. The addition of LH and FSH to the culture medium resulted in a remarkable stimulation of progesterone release by cells isolated in estrus. The highest concentration of estrogens in control cultures was observed in granulosa cells isolated at 18.00 h in proestrus. Exogenous LH and FSH stimulated the release of estrogen from the cells isolated on the days of estrus, metestrus and diestrus. Cultured granulosa cells maintained similar pattern of progesterone and estrogen release as the whole follicles did in vitro and in vivo.

Effect of exogenous hormones on the activity of delta 5,3 beta-hydroxysteroid dehydrogenase in cultured granulosa cells from proestrus and preovulatory rat ovarian follicles.

Activity of delta 5,3 beta-hydroxysteroid dehydrogenase (delta 5,3 beta-OH SD) in cultured granulosa cells isolated from rat ovarian follicles at various hours of proestrus was histochemically investigated. Control cultures as well as cultures with addition of luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin, and estradiol were carried on. In control cultures activity of the enzyme followed more or less the pattern observed in vivo. Exogenous LH added during preovulatory LH surge showed additive effect on enzyme activity. Other hormones stimulated enzyme activity on the morning of proestrus and at the time close to ovulation, when prolactin exerted most stimulatory effect.