Formation of CuInSe2 absorber layers formed using co-electrodeposition combined with selenization

Stoichiometric CuInSe2 absorber layers were formed using co-electrodeposition coupled with selenization. We investigated the influence of the metal ion ratio, supporting electrolyte, and deposition voltages on the structural and chemical properties of Cu-In alloys. The increases in deposition voltage and metal ion concentration helped to form In-rich Cu-In alloy with dendrite structure composed of a long central trunk with secondary branches. In addition, on increasing the concentration of the supporting electrolyte, the ratio of In to Cu in the Cu-In alloy increased, and surface morphology improved. Finally, based on an optimized co-electrodeposition process, the selenization of Cu-In alloys using the evaporation of the Se element was employed to form high quality CuInSe2 absorber layers.     

Effect of substrate temperature on the photoelectrochemical responses of Ga and N co-doped ZnO films

Ga–N co-doped ZnO thin films with reduced bandgaps were deposited on F-doped tin-oxide-coated glass by radio-frequency magnetron sputtering at different substrate temperatures in mixed N₂ and O₂ gas ambient. We found that Ga–N co-doped ZnO films exhibited enhanced crystallinity when compared to undoped ZnO films grown under the same conditions. Furthermore, Ga–N co-doping ensured enhanced N-incorporation ZnO thin films as the substrate temperature is increased. As a result, Ga–N co-doped ZnO thin films exhibited much improved photoelectrochemical (PEC) response, compared to ZnO thin films. Our results therefore suggest that the passive co-doping approach could be a means to improve PEC response for bandgap-reduced wide-bandgap oxides through impurity incorporation.     

Influence of zinc precursors and surfactants on the preparation of Ag-containing materials by electron beam irradiation

Ag-Zn bimetallic nanocomposites or Ag2S precipitates were produced by irradiating a mixture of AgNO3 and Zn(NO3)2, and another mixture of AgNO3 and ZnS with an electron beam in an aqueous phase. Surfactants of poly vinyl alcohol (PVA) and poly ethylene glycol (PEG) induced a slightly different formation of particles during this process.     

Process Evaluation of AISI 4340 Steel Manufactured by Laser Powder Bed Fusion

Laser powder bed fusion (L-PBF) involves the consolidation of metal powder, layer by layer, through laser melting and solidification. In this study, process parameters are optimized for AISI 4340 steel to produce dense and homogeneous structures. The optimized process parameters produce mechanical properties at the center of the build plate that are comparable to wrought in the vertical and horizontal orientations after heat treatment and machining. Four subsequent builds are filled with specimens to evaluate the mechanical behavior as a function of location and orientation. Variations in the mechanical properties are likely due to recoater blade interactions with the powder and uneven gas flow. The results obtained in this study are analyzed to assess the reliability and reproducibility of the process. A different build evaluates the performance of near-net-shaped tensile specimens angled 35°-90° from the build plate surface (horizontal). Ductility measurements and surface roughness vary significantly as a function of the build angle. In the stress-relieved and as-built conditions, the mechanical behavior of vertically oriented specimens exhibits somewhat lower and more variable ductility than horizontally oriented specimens. Therefore, several process variables affect the mechanical properties of parts produced by the L-PBF process.     

Physiological activities of ginsenoside-rich fraction isolated from Panax ginseng leaves

In order to develop the new physiologically active materials from the leaves of Panax ginseng C.A. Meyer, the ginsenoside-rich fraction (GL-1) was isolated from ginseng leaves and physiological activities were examined. GL-1 contained crude saponin (ginsenosides, 58.00%) and component ginsenoside analysis using high performance liquid chromatography (HPLC) showed that the major ginsenosides of GL-1 were Re, Rg1, Rc, and F2 and their contents were 34.42, 20.73, 18.42, and 8.60%, respectively. ABTS and DPPH radical scavenging activities of GL-1 were 75.14 and 39.28% at 10,000 μg/mL, respectively. Superoxide anion radical scavenging activity was 70.94% at 1,000 μg/mL. GL-1 also expressed the considerable anti-complementary activity in dose-dependent manner. Results obtained by crossed immunoelectrophoresis using anti-human C3 and anti-complementary activity in the absence of Ca⁺⁺ ion suggested that complement activation by GL-1 from ginseng leaves occur via both alternative and classical pathways.     

Macrophage stimulating polysaccharide purified from peels of grape (Vitis labrusca)

To characterize the macrophage stimulating polysaccharide in grape (Vitis labrusca) peels, the active crude polysaccharide (VL-3) has been fractionated from the hot-water extract of grape peels. A macrophage stimulating polysaccharide-rich fraction (VL-3IIb-1-1) was purified from VL-3 by 3 successive column chromatographies on DEAE-Sepharose CL-6B, Sepharose CL-6B, and Sephacryl S-300. VL-3IIb-1-1 was eluted as a single peak on high performance liquid chromatography (HPLC) and its molecular weight was estimated to be 194 kDa. VL-3IIb-1-1 consisted mainly of Ara and Gal in addition to uronic acid (GalA+GlcA) (molar ratio 1.00:0.81:0.72). Methylation analysis indicated that VL-3IIb-1-1 consisted mainly of terminal Araf, 4- or 5-linked Ara, 2,4-branched Rha, 6- or 3,4- or 3,6-branched Gal, and 3,4,6-branched Glc. Single radial gel diffusion also indicated that VL-3IIb-1-1 showed an intermediate reactivity with β-glucosyl-Yariv antigen. In addition, oral administration of VL-3IIb enhanced the stimulatory responses of macrophage stimulating activity ex vivo. Therefore, VL-3IIb-1-1 purified from grape peels is suggested to be pectic polysaccharide with arabino-3,6-galactan, and it is assumed that VL-3IIb-1-1 plays an important role for expression of its activity.     

Radiolytic production of Ag-containing nanocomposite colloids in presence of lithium ions

This research is motivated to prepare homogeneous and less aggregated nanostructured composites for potential scintillators. Poly ethylene glycol (PEG)-protected approximately 5 nm and approximately 29 nm sized Ag nanoparticles and Ag-Zn nanocomposites were relatively prepared by electron-beam irradiation on Ag+ and Zn2+ solutions with the aids of stabilizers and 6Li+ at room temperature under atmospheric pressure. Especially the 6Li+, which was used for a neutron absorption purpose, played a part the Ag-Zn nanocolloids to less aggregate in the aqueous phase by making partial complexes with stabilizers containing Ag-Zn. To be a potential scintillator, the Ag-Zn nanocomposites have to show an optical response to radiation. Therefore, optical luminescence, which resembles the concept of detecting light without the requirement of a neutron absorbent (convertor) for a neutron scitillator, of the nanocomposites was tested.     

Enhanced electron transport in mesoporous TiO2 films modified by sol-gel necking for dye-sensitized solar cells

Mesoporous TiO2 films modified via sol-gel necking were fabricated by dispersing Ti tetra-isopropoxide (TTIP; 8 to 16 wt% over TiO2) with TiO2 nanoparticles in isopropyl alcohol. The dye-sensitized solar cells (DSSCs) with 13 wt% TTIP-modified TiO2 film exhibited significantly improved overall energy conversion efficiency, despite having less adsorbed dye when compared with DSSCs with untreated and TiCl4 post-treated TiO2 films. The improvement can be attributed to the sol-gel necking (or interconnection) between the nanoparticles which leads to a much faster electron transport and a suppression of the recombination (or back electron transfer) between the TiO2 and electrolyte.     

Anti-complementary activity of enzyme-treated traditional Korean rice wine (Makgeolli) hydrolysates

BACKGROUND: Makgeolli brewed from rice contains about 150 g kg^?1 alcohol and has a fragrance as well as an acidic and sweet taste. During the brewing process, by‐products such as rice bran and brewery cake are produced. At the end of fermentation the matured mash is transferred to a filter cloth and the Makgeolli is squeezed out from the cake, leaving the lees of the mash. These by‐products have continued to increase every year, resulting in an ecological problem. It is therefore important to develop new uses for them. The objective of this study was to use the by‐products from the brewing of Makgeolli as a valuable functional food or nutraceutical. RESULTS: The anti‐complementary activities of crude polysaccharides isolated from Cytolase hydrolysates of Makgeolli lees at concentrations of 1000 and 500 µg mL^?1 were 84.15 and 78.70% respectively. The activity of polysaccharide krestin (PSK) was 60.00% at 1000 µg mL^?1. The active polysaccharide obtained with Cytolase comprised mainly glucose and mannose (molar ratio 1.00:0.62). CONCLUSION: Glucose‐ and mannose‐rich crude polysaccharides were isolated from the Cytolase hydrolysate of Makgeolli lees. The polysaccharides retain anti‐complementary activity to enhance the immune system as a functional food or nutraceutical. Copyright © 2011 Society of Chemical Industry     

Influence of gas ambient on the synthesis of co-doped ZnO:(Al,N) films for photoelectrochemical water splitting

Al and N co-doped ZnO thin films, ZnO:(Al,N), are synthesized by radio-frequency magnetron sputtering in mixed Ar and N₂ and mixed O₂ and N₂ gas ambient at 100 °C. The ZnO:(Al,N) films deposited in mixed Ar and N₂ gas ambient did not incorporate N, whereas ZnO:(Al,N) films grown in mixed O₂ and N₂ gas ambient showed enhanced N incorporation and crystallinity as compared to ZnO:N thin films grown in the same gas ambient. As a result, ZnO:(Al,N) films grown in mixed O₂ and N₂ gas ambient showed higher photocurrents than the ZnO:(Al,N) thin films deposited in mixed Ar and N₂ gas ambient. Our results indicate that the gas ambient plays an important role in N incorporation and crystallinity control in Al and N co-doped ZnO thin films.