Microstructure and mechanical properties of physical vapor deposited Cu/W nanoscale multilayers: Influence of layer thickness and temperature

Based on our previous knowledge on Cu/Nb nanoscale metallic multilayers (NMMs), Cu/WNMMs show a good potential for applications as heat skins in plasma experiments and armors, and it could be expected that the substitution of Nb byWwould increase the strength, particularly at high temperatures. To check this hypothesis, Cu/WNMMs with individual layer thicknesses ranging between 5 and 30 nm were deposited by physical vapour deposition, and their mechanical properties were measured by nanoindentation. The results showed that, contrary to Cu/Nb NMMs, the hardness was independent of the layer thickness and decreased rapidlywith temperature, especially above 200 °C. This behavior was attributed to the growth morphology of theWlayers aswell as the jagged Cu/W interface, both a consequence of the lowW adatom mobility during deposition. Therefore, future efforts on the development of Cu/Wmultilayers should concentrate on optimization of theWdeposition parameters via substrate heating and/or ion assisted deposition to increase the W adatom mobility during deposition.

Cu(In,Ga)Se2 absorber thinning and the homo-interface model: Influence of Mo back contact and 3-stage process on device characteristics

Thinning the absorber layer is one of the possibilities envisaged to further decrease the production costs of Cu(In,Ga)Se2 (CIGSe) thin films solar cell technology. In the present study, the electronic transport in submicron CIGSe-based devices has been investigated and compared to that of standard devices. It is observed that when the absorber is around 0.5 μm-thick, tunnelling enhanced interface recombination dominates, which harms cells energy conversion efficiency. It is also shown that by varying either the properties of the Mo back contact or the characteristics of 3-stage growth processing, one can shift the dominating recombination mechanism from interface to space charge region and thereby improve the cells efficiency. Discussions on these experimental facts led to the conclusions that 3-stage process implies the formation of a CIGSe/CIGSe homo-interface, whose location as well as properties rule the device operation; its influence is enhanced in submicron CIGSe based solar cells.

Reexamination of the mechanism of hydroxyl radical adducts formed from the reaction between familial amyotrophic lateral sclerosis-associated Cu,Zn superoxide dismutase mutants and H2O2

Amyotrophic lateral sclerosis (ALS) involves the progressive degeneration of motor neurons in the spinal cord and motor cortex. Mutations to Cu,Zn superoxide dismutase (SOD) linked with familial ALS are reported to increase hydroxyl radical adduct formation from hydrogen peroxide as measured by spin trapping with 5,5′-dimethyl-1-pyrrolline N-oxide (DMPO). In the present study, we have used oxygen-17-enriched water and H2O2 to reinvestigate the mechanism of DMPO/⋅OH formation from the SOD and SOD mutants. The relative ratios of DMPO/⋅17OH and DMPO/⋅16OH formed in the Fenton reaction were 90% and 10%, respectively, reflecting the ratios of H217O2 to H216O2. The reaction of the WT SOD with H217O2 in bicarbonate/CO2 buffer yielded 63% DMPO/⋅17OH and 37% DMPO/⋅16OH. Similar results were obtained from the reaction between familial ALS SOD mutants and H217O2: DMPO/⋅17OH (64%); DMPO/⋅16OH (36%) from A4V and DMPO/⋅17OH (62%); and DMPO/⋅16OH (38%) from G93A. These results were confirmed further by using 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide spin trap, a phosphorylated analog of DMPO. Contrary to earlier reports, the present results indicate that a significant fraction of DMPO/⋅OH formed during the reaction of SOD and familial ALS SOD mutants with H2O2 is derived from the incorporation of oxygen from water due to oxidation of DMPO to DMPO/⋅OH presumably via DMPO radical cation. No differences were detected between WT and mutant SODs, neither in the concentration of DMPO/⋅OH or DEPMPO/⋅OH formed nor in the relative incorporation of oxygen from H2O2 or water.

Production of methanol from CO2 electroreduction at Cu2O and Cu2O/ZnO-based electrodes in aqueous solution

In this study, we examine the performance of Cu2O and Cu2O/ZnO surfaces in a filter-press electrochemical cell for the continuous electroreduction of CO2 into methanol. The electrodes are prepared by airbrushing the metal particles onto a porous carbon paper and then are electrochemically characterized by cyclic voltammetry analyses. Particular emphasis is placed on evaluating and comparing the methanol production and Faradaic efficiencies at different loadings of Cu2O particles (0.5, 1 and 1.8 mg cm−2), Cu2O/ZnO weight ratios (1:0.5, 1:1 and 1:2) and electrolyte flow rates (1, 2 and 3 ml min−1 cm−2). The electrodes including ZnO in their catalytic surface were stable after 5 h, in contrast with Cu2O-deposited carbon papers that present strong deactivation with time. The maximum methanol formation rate and Faradaic efficiency for Cu2O/ZnO (1:1)-based electrodes, at an applied potential of −1.3 V vs. Ag/AgCl, were r = 3.17 × 10−5 mol m−2 s−1 and FE = 17.7 %, respectively. Consequently, the use of Cu2O–ZnO mixtures may be of application for the continuous electrochemical formation of methanol, although further research is still required in order to develop highly active, selective and stable catalysts the electroreduction of CO2 to methanol.

Hydrogen Production by Steam Reforming of Ethanol on Rh-Pt Catalysts: Influence of CeO2, ZrO2, and La2O3 as Supports

CeO2-, ZrO2-, and La2O3-supported Rh-Pt catalysts were tested to assess their ability to catalyze the steam reforming of ethanol (SRE) for H2 production. SRE activity tests were performed using EtOH:H2O:N2 (molar ratio 1:3:51) at a gaseous space velocity of 70,600 h−1 between 400 and 700 °C at atmospheric pressure. The SRE stability of the catalysts was tested at 700 °C for 27 h time on stream under the same conditions. RhPt/CeO2, which showed the best performance in the stability test, also produced the highest H2 yield above 600 °C, followed by RhPt/La2O3 and RhPt/ZrO2. The fresh and aged catalysts were characterized by TEM, XPS, and TGA. The higher H2 selectivity of RhPt/CeO2 was ascribed to the formation of small (~5 nm) and stable particles probably consistent of Rh-Pt alloys with a Pt surface enrichment. Both metals were oxidized and acted as an almost constant active phase during the stability test owing to strong metal-support interactions, as well as the superior oxygen mobility of the support. The TGA results confirmed the absence of carbonaceous residues in all the aged catalysts.

The differential evolution of hot- and cold-dust in galaxies in the last 7.5 GYR

Tese de mestrado em Física, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016

A criança pinta o céu de “verde”. Até que ponto lhe devemos dizer que o céu é azul?

Relatório de estágio apresentado para a obtenção do grau de Mestre em Ensino pré-escolar e 1º ciclo do ensino básico

Composition of rocks and minerals from the Mid-Atlantic Ridge 5-7°N

The monograph summarizes geological and metallogenic data on the Mid-Atlantic Ridge obtained during research expeditions of the Geological Institute RAS in 2000-2003. Formation of the earth crust in the region, structure of the rift zone, structure of the newly discovered Bogdanov Fracture Zone, neotectonic deformations, metallogenic peculiarities, prospecting criteria of ocean ore mineralization are under consideration.

Chemical composition of minerals in peridotides from the 15°20'N transform fault, Atlantic Ocean

Information about the first finding of awaruite in oceanic peridotites is given. Petrography of rocks, mineralogy, and minerals associated with awaruite are characterized.

Operator, organizational, direct support, and general support maintenance manual : loader, scoop type, DED, 4 wheel drive, pneumatic tired, hinged frame steer, 2 1/2 cu. yd. multi-purpose bucket (J.I. Case model MW-24), FSN 3805-253-0627.

"December 1970."

Unit, direct support, and general support maintenance repair parts and special tools lists (including depot maintenance repair parts and special tools lists) : crane-shovel, crawler mounted, diesel engine driven, 12-1/2 ton capacity, rated with 3/4 cu yd (NSN 3810-00-937-3939), Thew-Lorain model L-36M.

"August 1992."

Organizational maintenance repair parts and special tools lists : loader, scoop type, diesel engine, 4-wheel drive, rear wheel steerable pneumatic tires, 2 1/2 cu yd, w/ multi-segment bucket, (Frank G. Hough model H-90CM) FSN 3805-995-3236.

Includes index.

Organizational maintenance repair parts and special tools lists : scraper, earth moving, towed, 18 cu. yd. scoop NSN 3805-00-075-3312 : Le Tourneau-Westinghouse (WABCO) model CT 4.

Includes index.

Organizational maintenance repair parts and special tools lists : loader, scoop type, DED, 4-wheel drive, pneumatic tired hinged frame steer 2 1/2 cu yd, multi-purpose bucket, NSN 3805-00-169-4711, J.I. Case model MW24B.

Includes index.

Direct support and general support maintenance repair parts and special tools lists (including depot maintenance repair parts and special tools) : loader, scoop type, DED, 4-wheel drive, pneumatic tired hinged frame steer 1 1/2 cu yd, multi-purpose bucket, NSN 3805-00-169-4711, J.I. Case model MW24B.

Includes index.