FERRATES: SYNTHESIS, PROPERTIES AND APPLICATIONS IN WATER AND WASTEWATER TREATMENT.

The higher oxidation states of iron (Fe(VI) and Fe(V) in particular) have been shown to be strongly oxidizing in enzymatic systems, where they can carry out aliphatic hydrogen abstraction. In addition, they have been postulated as intermediates in Fenton-type systems. Fe(VI) itself is relatively stable and has been shown to have potential as an oxidant in the so-called ''green'' treatment of polluted waters. By contrast, Fe(V) is a relatively short-lived transient when produced in aqueous solution in the absence of strongly bonding ligands other than hydroxide, a feature that has limited studies of its reactivity. Fe(VI) has been proposed to be useful in battery design and a very interesting study suggested that ferrate may be able to oxidize insoluble chromium to chromate and thus serve to remove chromium contamination in the Hanford radioactive waste tanks

Invited PaperNext generation focal plane array for infrared astronomy

A short wavelength 2048x2048 focal plane array (FPA) with 18 µm pixel pitch is being developed for infrared astronomy. The HAWAII-2 FPA will be a hybrid comprising a HgCdTe-based detector array flip-chip bonded to a CMOS silicon multiplexer through indium interconnects. The first FPAs will have cut-off wavelength of 2.5 µm, but the readout is being designed to service detector cutoff wavelengths beyond 15 µm. The 18 µm pixel pitch was selected to accommodate both reasonable telescope optics and fabrication of the large readout (=40x40mm2) using world-class sub-micron photolithography to maximize yield of high quality devices. Defect-free multiplexer yield >5% is expected in the first lot which will be fabricated on Rockwell's commercial production line in 0,8 µm CMOS. The HgCdTe photovoltaic detector arrays will be fabricated on ≥3" diameter sapphire or silicon wafers. We also report the latest 1024x1024 FPA results with 2.5 µm HgCdTe detectors on sapphire substrates

A kinetic study of the electrochemical oxidation of maleic acid on boron doped diamond

Maleic acid (MA) is one of the main intermediates formed during mineralization, by electrooxidation, of aromatic compounds contained in aqueous wastes. This work investigates oxidation of maleic acid with or without the presence of oxalic acid (OA) and formic acid (FA) in aqueous solution by using boron-doped diamond (BDD) electrodes. OA and FA are the main products formed in MA electrooxidation. Voltammetric studies conducted with a BDD electrode of small surface (0.196 cm2) show that MA oxidation takes place at a potential very close to that of the discharge of water. But, under potentiostatic conditions and at concentrations higher than 0.001 M, adsorption of MA blocks its own oxidation. Oxalic and formic acids are before the discharge of water. Again, the presence of maleic acid blocks the oxidation of formic and oxalic acids. Galvanostatic electrolyses of aqueous solutions of MA, OA, FA and mixtures of theses acids were conducted on a BDD electrode. Electrolyses were controlled by measurements of Total Organic Carbon, Chemical Oxygen Demand and by Liquid Chromatography. Results showed that MA was totally mineralized; FA and OA were very low concentration intermediaries. Electrolyses of solutions containing MA, initially in the presence of OA or FA, showed that the OA was oxidized at the same rate as the MA, whereas the FA oxidation began only when the MA had completely disappeared. These results suggest that OA oxidizes by a mass transport limited process coupled with a direct electron transfer with the anode. Under galvanostatic conditions, maleic acid and formic acid are probably oxidized via OH· radicals generated by water discharge

Quantitative molecular orbital energies within a G0W0 approximation

Using many-body perturbation theory within the $G_0W_0$ approximation, we explore routes for computing the ionization potential (IP), electron affinity (EA), and fundamental gap of three gas-phase molecules -- benzene, thiophene, and (1,4) diamino-benzene -- and compare with experiments. We examine the dependence of the IP on the number of unoccupied states used to build the dielectric function and the self energy, as well as the dielectric function plane-wave cutoff. We find that with an effective completion strategy for approximating the unoccupied subspace, and a converged dielectric function kinetic energy cutoff, the computed IPs and EAs are in excellent quantitative agreement with available experiment (within 0.2 eV), indicating that a one-shot $G_0W_0$ approach can be very accurate for calculating addition/removal energies of small organic molecules. Our results indicate that a sufficient dielectric function kinetic energy cutoff may be the limiting step for a wide application of $G_0W_0$ to larger organic systems