Preparation of hydrogen titanate nanotube/FTO glass thin film obtained by the layer-by-layer-self assembling method for water splitting

Hydrogen titanate nanotube (H-TiNT) particles were coated porously on a fluorine-doped tin oxide glass using the layer-by-layer self assembling method and then heat-treated at temperatures below 600 degrees C for 10 min in air. The microstructure, crystallinity, and optical absorbance of the heat-treated H-TiNT thin film were investigated using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and UV-vis spectroscopy, respectively. Also, I-V characteristics of the fibrous H-TiNT particles in the thin film using linear cycle voltammetry under ultraviolet-A irradiation were analyzed to have a maximum current value at applied voltages with the increase in heating temperature for economic water splitting.     

Enhanced photocurrent generation of binary self-assembled monolayers of di-(3-aminopropyl)-viologen and methylviologen on indium tin oxide

The binary self-assembled monolayers (SAMs) of di-(3-aminopropyl)-viologen (DAPV) and methylviologen (MV) molecules on indium tin oxide (ITO) were prepared by dipping the DAPV SAMs/ITO substrates into MV solution. The DAPV-MV SAM films were characterized by UV-vis. absorption spectroscopy, Rutherford backscattering spectroscopy, and cyclic voltammetry. Optical band gap, lowest unoccupied molecular orbital, and highest occupied molecular orbital of DAPV-MV SAMs were measured to be 1.6, -4.3, and -5.9 eV, respectively. We found that although DAPV SAMs have a quantum yield of 0.11%, the binary SAM films have a good quantum yield of 2.30%, which was 20 times higher than that of DAPV SAMs on ITO. This result may be due to the higher adsorption property of the binary SAMs for the light in visible range compared to that of DAPV SAMs. From this study, we demonstrated that the photocurrent generation systems with a high quantum yield can be obtained by the functional binary SAMs.     

Simple two-step fabrication method of Bi2Te3 nanowires

Bismuth telluride (Bi2Te3) is an attractive material for both thermoelectric and topological insulator applications. Its performance is expected to be greatly improved when the material takes nanowire structures. However, it is very difficult to grow high-quality Bi2Te3 nanowires. In this study, a simple and reliable method for the growth of Bi2Te3 nanowires is reported, which uses post-sputtering and annealing in combination with the conventional method involving on-film formation of nanowires. Transmission electron microscopy study shows that Bi2Te3 nanowires grown by our technique are highly single-crystalline and oriented along [110] direction.     

Preparation and characterization of polyacrylamide cryogels produced from a high‐molecular‐weight precursor. II. The influence of the molecular weight of the polymeric precursor

Polyacrylamide gels and cryogels were prepared by the crosslinking reaction of polyacrylamide (a polymeric precursor) with glutaric aldehyde (a crosslinking agent) in liquid and moderately frozen aqueous media, respectively. Polymeric precursors of different viscosity‐ averagemolecular weights (0.3, 1, 3, and 9 MDa) were used. The molecular weight of the precursors, as well as the reaction temperature and concentration of the crosslinking agent, exerted a pronounced influence on the efficiency of gelation (gel fraction yield) and on the properties (swelling capability) and structural peculiarities of the resulting gels (reference samples) and cryogels. The highest efficacy was inherent in the cryotropic gelation process when the polymeric precursor had a molecular weight of about 3 MDa, whereas the implementation of polyacrylamides of lower (0.3 or 1 MDa) or higher (9 MDa) molecular weights diminished the gel formation efficiency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Enhanced production of oceanic dimethylsulfide resulting from CO₂-induced grazing activity in a high CO₂ world

Oceanic dimethylsulfide (DMS) released to the atmosphere affects the Earth's radiation budget through the production and growth of cloud condensation nuclei over the oceans. However, it is not yet known whether this negative climate feedback mechanism will intensify or weaken in oceans characterized by high CO(2) levels and warm temperatures. To investigate the effects of two emerging environmental threats (ocean acidification and warming) on marine DMS production, we performed a perturbation experiment in a coastal environment. Two sets of CO(2) and temperature conditions (a pCO(2) of ～900 ppmv at ambient temperature conditions, and a pCO(2) of ～900 ppmv at a temperature ～3 °C warmer than ambient) significantly stimulated the grazing rate and the growth rate of heterotrophic dinoflagellates (ubiquitous marine microzooplankton). The increased grazing rate resulted in considerable DMS production. Our results indicate that increased grazing-induced DMS production may occur in high CO(2) oceans in the future.     

Retrieval of Aerosol Extinction in the Lower Troposphere Based on UV MAX-DOAS Measurements

Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) has been utilized in recent years as a means of deriving vertical profiles of aerosol and trace gases; however, this new technique requires further validation because few studies have investigated its capability. In this study, vertical distributions of aerosol extinction coefficients (AECs) in the lower troposphere were retrieved by applying a recently developed aerosol-retrieval algorithm to O₄ slant column densities (SCDs) measured at a UV wavelength (356 nm) using the MAX-DOAS technique. The MAX-DOAS measurements were conducted at the Korea Global Atmosphere Watch Observatory (KGAWO) located off the west coast of Korea during a period of seven cloudless days in May and June 2005. The AECs measured by UV MAX-DOAS varied from 0.05 to 0.73 km^?1 in the 0–1 km layer and from 0.01 to 0.20 km^?1 in the 1–2 km layer. The AECs for the 1–2 km layer from UV MAX-DOAS are in agreement with lidar data within about 60%. Our results demonstrate the ability of MAX-DOAS as a remote sensing technique for surface aerosol measurements.