Natural dye-based photoelectrode for improvement of solar cell performance

In the present paper, photovoltaic studies of dye-sensitized solar cells (DSSCs) based on betacyanin/TiO₂ and betacyanin/WO₃–TiO₂ have been done. The cell performances were compared through I–V curves and wavelength dependant photocurrent measurements for the two new types of DSSCs. The TiO₂-coated DSSC showed the photovoltage and photocurrent of 300 mV and 4.96 mA/cm², whereas the cell employing WO₃–TiO₂ photoelectrode showed the values 435 mV and 9.86 mA/cm², respectively. The conversion efficiency of TiO₂ based dye-sensitized solar cell was found to be 0.69 %, while WO₃–TiO₂-based cell exhibited a higher conversion efficiency of 2.2 %. The better performance of the WO₃–TiO₂ dye-sensitized solar cell photoelectrode is thought to be due to an inherent energy barrier at the electrode/electrolyte interface leading to the reduced recombination of photoinduced electrons.     

Kinetics and mechanism of the ruthenium(III)-catalysed oxidation of aminoalcohols by cerium(IV) in a sulphuric acid medium

Summary The kinetics of the ruthenium(III)-catalysed oxidation of primary (viz. 2-aminoethanol and 3-aminopropanol) secondary (diethanolamine) and tertiary aminoalcohols (triethanolamine) by cerium(IV) in a sulphuric acid medium have been studied spectrophotometrically. The reactions exhibit a zero-order rate-dependence with respect to the oxidant and first-order rate-dependence with respect to each of the substrate and catalyst. First order dependence of rate in sulphuric acid is found for primary aminoalcohols. A suitable mechanism, consistent with the observed kinetic data, is proposed.     

Photoelectric effects in chlorophyll membranes

Photoinduced potentials and currents and photo-electroosmotic velocities were measured across cellulose acetate membranes impregnated with chlorophyll pigments. Chlorophyll was extracted by both solvent extraction, Chl^s, and column chromatography, Chl. Photoelectric effects in membranes prepared with the following pigments were investigated: (i) Chl^s-a + β-carotene, (ii) Chl^s-b + xanthophyll, (iii) Chl^s-a, (iv) Chl^s-b, (v) β-carotene, (vi) xanthophyll, (vii) Chl^s-a + anthraquinone, (viii) Chl^s-b + anthraquinone, (ix) Chl-a, (x) Chl-b, (xi) Chl-a + anthraquinone, (xii) Chl-b + anthraquinone, (xiii) Chl-a + benzoquinone, and (xiv) Chl-b + benzoquinone. β-Carotene, xanthophyll, Chl-a and Chl-b obrained by chromatographic separation do not show a photoinduced potential or current. However, these effects are observed when “pure” (doubly chromatographed) Chl-a or Chl-b are mixed with anthraquinone or benzoquinone. These effects are observed in systems (i), (ii), (iii), (iv), (vii) and (viii) involving Ch^s. Although photoinduced potentials and photoinduced currents are not observed in Chl-a or Chl-b membranes, photoelectroosmosis is still observed. p]Both photoinduced potentials and currents are found to depend on pH. When the pH is changed appropriately, Chl^s-a acts as photocathode while Chl^s-b becomes a photoanode. Photocurrents are considerably enhanced when the pH is lowered. The change of photopotential with temperature is found to be insignificant. Photoelectroosmosis is always found to be directed towards the dark side, regardless of the polarity of the electrodes. A model based on the role of plastiquinone has been proposed to explain these phenomena, which have excellent reproducibility. The model predicts that ΔpH = (pH)_d — (PH)₁ (where (pH)_d and (pH)₁ denote the pH on the dark and illuminated side of the membrane respectively) would be positive when the pH of the bathing solution is higher than approximately 7, while it would be negative for lower pH. This behaviour is observed in the case of mixture of pure Chl-a + anthraquinone and pure Chl-b + benzoquinone. The model also predicts photoelectroosmosis irrespective of the presence of plastiquinone, in agreement with experimental observation.     

Analytical Application of Deapg as Gravimetric Reagent II,Estimation of Pt(IV)

p-Diethylaminoanil of phenylglyoxal (abbreviated as DEAPG) precipitates Platinum (IV) quantitatively and gives greyish brown complex in the pH range 5.4 to 5.8 by adding slightly more than theoretical quantity of the ligand. It can be used for the gravimetric estimation of Pt(IV) either alone or in the presence of foreign ions.     

Highly bacterial resistant silver nanoparticles: synthesis and antibacterial activities

In this article, we describe a simple one-pot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO₃ using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block co-polymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (σ = 18.3%) and 31.1 ± 4.5 nm (σ = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive (Bacillus megaterium and Staphylococcus aureus), and three Gram negative (Escherichia coli, Proteus vulgaris and Shigella sonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.     

W-Spaces and Pseudo-differential Operators

In this article we improve the characterisation of [R.S. Pathak and S.K. Upadhyay (1994). W p -space and Fourier transformation. Proc. Amer. Math Soc ., 121 (3), 733-738.] and study the properties of pseudo-differential operator on the space , where z 1 , M 1 are convex functions and a, b are positive constants.     

Some relations between vector variational inequality problems and nonsmooth vector optimization problems using quasi efficiency

This paper deals with the relations between vector variational inequality problems and nonsmooth vector optimization problems using the concept of quasi efficiency. We identify the vector critical points, the weak quasi efficient points and the solutions of the weak vector variational inequality problems under generalized approximate convexity assumptions. To the best of our knowledge such results have not been established till now.