Emulsion templating to obtain dual-size-scale mesoporous titania coatings

Meso- and macroporous TiO₂ coatings have been fabricated using oil-in-water emulsions as the templating phase. Coatings with interpenetrating, polydisperse pore structures are obtained which are useful for applications such as dye sensitized solar cells (DSSC), where permeation of one or more reactants into the inner surface areas of the coating microstructure is critical. Very uniform, defect free coatings are obtained with commercially available TiO₂ nanopowder, with pores in the range of 30–1000 nm. Characterization of the coatings was performed using mercury porosimetry and electron microscopy.     

Structural consequences of replacement of an {alpha}-helical Pro residue in Escherichia coli thioredoxin

While it is well known that introduction of Pro residues intothe interior of protein     

Carboxymethylation of Cassia occidentalis seed gum

The seeds of Cassia occidentalis, an annual weed occurring throughout India, are a rich source of galactomannan gum. The gum derived from seed endosperm can be utilized in a number of industries to replace conventional gums. With a view to utilize the gum for broader applications, carboxymethylation of Cassia occidentalis seed gum was carried out. The reaction conditions were optimized with respect to concentration of monochloroacetic acid, sodium hydroxide, solvent ratio, reaction time, and reaction temperature. Rheological studies of carboxymethyl gum exhibited relatively high viscosity and stability vis‐a‐vis unmodified Cassia occidentalis gum. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1606–1611, 2004     

Facile chemical synthesis of W-Ag and W-Cu nanocomposites at low temperature

W-Ag (80.2W-19.8Ag, 70.4W-29.6Ag and 60.5W-39.5Ag) and W-Cu (79.7W-20.3Cu, 70.5W-29.5Cu and 59.8W-40.2Cu) nanocomposites in the size range of 24-30 nm have been synthesized by thermal decomposition of W(CO)6/CH3COOAg and W(CO)6/Cu(acac)2 in diphenyl ether as solvent at 220 degrees C in presence of oleic acid and hexadecyl amine and characterized. FTIR spectra have been used to explain the role of oleic acid and hexadecyl amine in the synthesis of W-Ag and W-Cu composite powders. XRD studies show that the tungsten phase is amorphous, whereas both Ag and Cu crystallize in fcc for as-synthesized W-Ag and W-Cu nanocomposites. These composite powders when annealed at 700 degrees C results in the formation of bcc tungsten and peaks corresponding to fcc silver and copper still persists. The particle size, shape and distribution of these nanocomposites of various compositions have been studied by SAXS, ESEM and TEM and found to be nearly spherical with the average diameters below 30 nm.     

Broad band optical characterization of sol-gel TiO2 thin film microstructure evolution with temperature

Titanium dioxide (TiO₂) thin films have been produced by spin coating a titanium isopropoxide sol on silicon wafer substrates. The structural evolution of the thin films in terms of decomposition, crystallization and densification has been monitored as a function of annealing temperature from 100 to 700 °C using optical characterization and other techniques. The effect of annealing temperature on the refractive index and extinction coefficient of these TiO₂ thin films was studied in the range of 0.62 to 4.96 eV photon energy (250-2000 nm wavelength) using spectroscopic ellipsometry. Thermal gravimetric analysis and atomic force microscopy support the ellipsometry data and provide information about structural transformations in the titania thin films with respect to different annealing temperatures. These data help construct a coherent picture of the decomposition of the sol-gel precursors and the creation of dense layers of TiO₂. It was observed that the refractive index increased from 2.02 to 2.45 at 2.48 eV (500 nm) in sol-gel spin coated titania films for annealing temperatures from 100 °C to 700 °C.     

Clustering effects in solution‐based nanoparticle/template hybrid coatings

Abstract— Templating processes with monodisperse polystyrene particles are being explored for a number of application areas, especially in microelectronics and optics. Classically, these depend on rather slow‐drying steps that allow for the polystyrene particles to gradually situate themselves into ordered arrays and patterns. On the other hand, many manufacturing processes are designed to operate much more rapidly (spin‐coating, roll‐coating, spray‐coating, etc.). The present work investigates the behavior of nanoparticle(titania)‐microparticle (polystyrene) hybrid solutions when processed with these rapid techniques. Very thin coatings were examined where the larger‐template particle‐particle interactions can be quantifiably observed and measured. This gives us insight into the conditions when structural order might be achievable in materials systems using these rapid, industrially important, coating techniques. The specific system that was investigated involves nanoscale titanium dioxide particles combined with monodisperse micron‐scale polystyrene template particles aimed at building flexible dye‐sensitized solar cells. For this application, the formation of strong physical networks of titanium dioxide nanoparticles with percolating interparticle channels for the electrolyte phase to reach all surfaces where dye molecules will reside is required.     

Co-deposition of Synthesized ZnO Nanoparticles into Ni-P Matrix Using Electroless Technique and Their Corrosion Study

Journal of Materials Engineering and Performance - In the present study, Ni-P-ZnO nanocomposite coating was developed on the surface of mild steel substrate by electroless technique. The second...     

Antimicrobial Peptide Mechanisms Studied by Whole-Cell Deuterium NMR

Much of the work probing antimicrobial peptide (AMP) mechanisms has focussed on how these molecules permeabilize lipid bilayers. However, AMPs must also traverse a variety of non-lipid cell envelope components before they reach the lipid bilayer. Additionally, there is a growing list of AMPs with non-lipid targets inside the cell. It is thus useful to extend the biophysical methods that have been traditionally applied to study AMP mechanisms in liposomes to the full bacteria, where the lipids are present along with the full complexity of the rest of the bacterium. This review focusses on what can be learned about AMP mechanisms from solid-state NMR of AMP-treated intact bacteria. It also touches on flow cytometry as a complementary method for measuring permeabilization of bacterial lipid membranes in whole bacteria.