18O isotope exchange measurements of photosystem II (PSII ) in thylakoids from wild-type and mutant Synechocystis have been performed to investigate binding of substrate water to the highaffinity Mn 4 site in the oxygen-evolving complex (OEC). The mutants investigated were D1-D170H, a mutation of a direct ligand to the Mn 4 ion, and D1-D61N, a mutation in the second coordination sphere. The substrate water 18 O exchange rates for D61N were found to be 0.16G0.02 s K1 and 3.03G0.32 s K1 for the slow and fast phases of exchange, respectively, compared with 0.47G0.04 s K1 and 19.7G1.3 s K1 for the wild-type. The D1-D170H rates were found to be 0.70G0.16 s K1 and 24.4G4.6 s K1 and thus are almost within the error limits for the wild-type rates. The results from the D1-D170H mutant indicate that the high-affinity Mn 4 site does not directly bind to the substrate water molecule in slow exchange, but the binding of non-substrate water to this Mn ion cannot be excluded. The results from the D61N mutation show an interaction with both substrate water molecules, which could be an indication that D61 is involved in a hydrogen bonding network with the substrate water. Our results provide limitations as to where the two substrate water molecules bind in the OEC of PSII.

The charge density of a TiO2 film deposited on a SiO2 -passivated silicon wafer is determined. The TiO2 is deposited by atmospheric pressure chemical vapor deposition at 400°C , and the SiO2 is grown thermally at 950°C . This TiO2–SiO2 stack is a useful coating for the front surface of a silicon solar cell, as it has a high optical transmission and a low density of interface states Dit(E) at the SiO2–Si interface. While these properties are beneficial to high efficiency solar cells, so too is a large charge density, as what occurs in Si3normalN4–SiO2 (+1012cm−2) and Al2normalO3–SiO2 (−1013cm−2) stacks. The Dit(E) and charge density of TiO2 -coated and SiO2 -passivated silicon are evaluated by capacitance–voltage and Kelvin probe measurements. The charge density of the TiO2 is within the conservative limits of −8.5 and −1×1011cm−2 after deposition and of −10 and +1×1011cm−2 after a subsequent 800°C oxygen anneal. Photoconductance measurements suggest that the dangling-bond defects at the SiO2–Si interface are predominantly donorlike and, hence, that the change density in the TiO2 is closer to the upper limits (less negative); this charge is too small to benefit solar cells.

Absrruct--Hotwire C M (HWCVD) deposited silicon rich nitride films were treated with 0 2 plasma using RF plesma setup. The thickngs o f this oxpitride film was measured using spectroscopic ellipsometry. The film was treated with 1343-aminoethyl) aminopropyl]-trlmethoxysilene (AEAPS) followed by Immobilizatioa of Human immunoglobulin (HIgG) on it. Surface morphology at various stages of experimentation was studied using AFM. Antibody Lmmobllized surface is further bvestigated using fluomcence mImscopy.

The recent availability of large format near-infrared detectors with sub-election readout noise is revolutionizing our approach to wavefront sensing for adaptive optics. However, as with all near-infrared detector technologies, challenges exist in moving from the comfort of the laboratory test-bench into the harsh reality of the observatory environment. As part of the broader adaptive optics program for the GMT, we are developing a near-infrared Lucky Imaging camera for operational deployment at the ANU 2.3 m telescope at Siding Spring Observatory. The system provides an ideal test-bed for the rapidly evolving Selex/SAPHIRA eAPD technology while providing scientific imaging at angular resolution rivalling the Hubble Space Telescope at wavelengths λ = 1.3-2.5 μm.

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