Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells

A direct borohydride fuel cell (DBFC) employing a poly (vinyl alcohol)hydrogel membrane electrolyte (PHME) is reported. The DBFC employs an AB(5) Misch metal alloy as anode and a goldplated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium borohydride as fuel and aqueous acidified solution of hydrogen peroxide as oxidant. Room temperature performances of the PHME-based DBFC in respect of peak power outputs; ex-situ cross-over of oxidant, fuel,anolyte and catholyte across the membrane electrolytes; utilization efficiencies of fuel and oxidant, as also cell performance durability are compared with a similar DBFC employing a NafionA (R)-117 membrane electrolyte (NME). Peak power densities of similar to 30 and similar to 40 mW cm(-2) are observed for the DBFCs with PHME and NME, respectively. The crossover of NaBH4 across both the membranes has been found to be very low. The utilization efficiencies of NaBH4 and H2O2 are found to be similar to 24 and similar to 59%, respectively for the PHME-based DBFC; similar to 18 and similar to 62%, respectively for the NME-based DBFC. The PHME and NME-based DBFCs exhibit operational cell potentials of similar to 1 center dot 2 and similar to 1 center dot 4 V, respectively at a load current density of 10 mA cm(-2) for similar to 100 h.

Ethyl 4-(3-hydroxyphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate

In the molecular structure of the title compound, C21H25NO4, the dihydropyridine ring adopts a flattened boat conformation while the cyclohexenone ring is in an envelope conformation. In the crystal structure, molecules are linked into a two-dimensional network parallel to (10 (1) over bar) by N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds. The network is generated by R-4(4)(30) and R-4(4)(34) graph-set motifs.

LbL Fabricated Poly(Styrene Sulfonate)/TiO2 Multilayer Thin Films for Environmental Applications

Fabrication of multilayer ultrathin composite films composed of nanosized titanium dioxide particles (P25, Degussa) and polyelectrolytes (PELs), such as poly(allyl amine hydrochloride) (PAH) and poly(styrene sulfonate sodium salt) (PSS), on glass substrates using the layer-by-layer (LbL) assembly technique and its potentia application for the photodegradation of rhodamine B under ultraviolet (UV) irradiation has been reported. The polyelectrolytes and TiO2 were deposited on glass substrates at pH 2.5 and the growth of the multilayers was studied using UV/vis speccrophotometer. Thicknes measurements of the films showed a linear increase in film thickness with increase in number of bilayers. The surface microstructure of the thin films was characterized by field emission scanning electron microscope. The ability of the catalysts immobilized by this technique was compared with TiO2 films prepared by drop casting and spin coating methods. Comparison has been made in terms of film stability and photodegradation of rhodamine B. Process variables such as the effect of surface area of the multilayers, umber of bilayers, and initial dye concentration on photodegradation of rhodamine B were studied. Degradation efficiency increased with increase in number of catalysts (total surface area) and bilayers. Kinetics analysis indicated that the photodegradation rates follow first order kinetics. Under maximum loading of TiO2, with five catalyst slides having 20 bilayers of polyelectrolyte/TiO2 on each, 100 mL of 10 mg/L dye solution could be degraded completely in 4 h. The same slides could be reused with the same efficiency for several cycles. This study demonstrates that nanoparticles can be used in wastewater treatment using a simple immobilization technique. This makes the process an attractive option for scale up.

Ethyl 2,6-dichloro-4-phenylquinoline-3-carboxylate

In the title compound,C18H13Cl2NO2,the quinoline ring system is almost planar (r.m.s.deviation 0.009 angstrom), and the phenyl and carboxylate planes are twisted away from it by 59.2 (1)and 65.9 (2)degrees,respectively.

Ethyl 6-chloro-2-oxo-4-phenyl-1,2-dihydroquinoline-3-carboxylate

In the title compound,C18H14ClNO3,the dihydroquinolin-2-one ring system is almost planar (r.m.s.deviation = 0.033 angstrom).The carboxylate plane and the phenyl group are twisted away from the dihydroquinolin-2-one ring system by 50.3(1) and 64.9(1)degrees,respectively.In the crystal structure, inversion-related molecules form R-2(2)(8)dimers via pairs of N-H center dot center dot center dot O hydrogen bonds.

Ethyl 2-acetyl-3-(4-bromoanilino)butanoate

The title compound, C14H18BrNO3, adopts an extended conformation, with all of the main-chain torsion angles associated with the ester and amino groups close to trans. In the crystal, inversion dimers linked by pairs of N-H center dot center dot center dot O hydrogen bonds are observed.

Ethyl 6-chloro-2-methyl-4-phenylquinoline-3-carboxylate

In the title compound, C19H16ClNO2, the quinoline ring system is planar (r.m.s. deviation = 0.008 angstrom). The phenyl group and the -CO2 fragment of the ester unit form dihedral angles of 60.0 (1) and 60.5 (1)degrees, respectively, with the quinoline ring system.

Comparison of performance parameters of poly(3,4 ethylenedioxythiophene) (PEDOT) based electrochromic device on glass with and without counter electrode

Conjugated polymers are promising materials for electrochromic device technology. Aqueous dispersions of poly(3,4-ethylenedioxythiophene)-(PEDOT) were spin coated onto transparent conducting oxide (TCO) coated glass substrates. A seven-layer electrochromic device was fabricated with the following configuration: glass/transparent conducting oxide (TCO)/PEDOT (main electrochromic layer)/gel electrolyte/prussian blue (counter electrode)/TCO/glass. The device fabricated with counter electrode (Prussian blue) showed a contrast of 18% and without counter electrode showed visible contrast of 5% at 632 nm at a voltage of 1.9 V. The comparison of the device is done in terms of the colouration efficiency of the devices with and without counter electrode.

Dielectric properties of Poly(vinylidene fluoride)/CaCu3Ti4O12 composites

The possibility of obtaining relatively high dielectric constant polymer-ceramic composite by incorporating the giant dielectric constant material, CaCu3Ti4O12 (CCTO) in a Poly(vinylidene fluoride) (PVDF) polymer matrix by melt mixing and hot pressing process was demonstrated. The structure, morphology and dielectric properties of the composites were characterized using X-ray diffraction, Thermal analysis. scanning electron microscope, and impedance analyzer. The effective dielectric constant a(epsilon(eff)) of the composite increased with increase in the volume fraction of CCTO at all the frequencies(100 Hz-1 MHz) under study. The dielectric loss did not show any variation up to 40% loading of CCTO, but showed an increasing trend beyond 40%. The room temperature dielectric constant as high as 95 at 100 Hz has been realized for the composite with 55 vol.% of CCTO, which has increased to about 190 at 150 degrees C. Theoretical models like Maxwell's, Clausius-Mossotti, Effective medium theory, logarithmic law and Yamada were employed to rationalize the dielectric behaviour of the composite and discussed. (C) 2010 Published by Elsevier Ltd.

Effect of substitution on molecular conformation and packing features in a series of aryl substituted ethyl-6-methyl-4-phenyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates

The supramolecular structures of eight aryl protected ethyl-6-methyl-4-phenyl-2-thioxo-1,2,3,4 tetrahydropyrimidine-5-carboxyl ates were analyzed in order to understand the effect of variations in functional groups on molecular geometry, conformation and packing of molecules in the crystalline lattice. It is observed that the existence of a short intra-molecular C-H center dot center dot center dot pi interaction between the aromatic hydrogen of the aryl ring with the isolated double bond of the six-membered tetrahydropyrimidine ring is a key feature which imparts additional stability to the molecular conformation in the solid state. The compounds pack via the cooperative involvement of both N-H center dot center dot center dot S=C and N-H center dot center dot center dot O=C intermolecular dimers forming a sheet like structure. In addition, weak C-H center dot center dot center dot O and C-H center dot center dot center dot pi intermolecular interactions provide additional stability to the crystal packing.

Ethyl 6-chloro-2-[(2-chloro-7,8-dimethylquinolin-3-yl)methoxy]-4-phenylquino line-3-carboxylate

In the title compound, C30H24Cl2N2O3, the two quinoline ring systems are almost planar [maximum deviations = 0.029 (2) and 0.018 (3) angstrom] and the dihedral angle between them is 4.17 (8)degrees. The dihedral angle between the phenyl ring and its attached quinoline ring is 69.06 (13)degrees. The packing is stabilized by C-H center dot center dot center dot O, C-H center dot center dot center dot N, weak pi-pi stacking [centroid-centroid distances = 3.7985 (16) and 3.7662(17) angstrom] and C-H center dot center dot center dot pi interactions.

Enzymatic Degradation of Poly(soybean oil-g-methyl methacrylate)

This study discusses grafting of methyl methacrylate units from thepolymeric soybean oil peroxide to produce poly(soybean oil-graft-methyl methacrylate) (PSO-g-PMMA). The degradation of this copolymer in solution was evaluated in the presence of different lipases, viz Candida rugosa (CR), Lipolase 100T (LP), Novozym 435 (N435) and Porcine pancreas (PP), at different temperatures The copolymer degraded by specific chain end scission and the mass fraction of the specific product evolved was determined The degradation was modeled using continuous distribution kinetics to determine the rate coefficients ofmenzymatic chain end scission and deactivation of the enzyme The enzymes, CR. LP and N435 exhibited maximum activity for the degradation of PSO-g-PMMA at 60 degrees C, while PP was most active at 50 degrees C. The thermal degradability of the copolymer, assessed by thermo-gravimetry, indicated that the activation energy of degradation of the copolymer was 154 kJ mol(-1), which was lesser than that of the PMMA homopolymer.

Transformation reactions of α-pinene—I : Reactions of ethyl (−)-2,2-dimethyl-3-ketocyclobutyl acetate

Some transformation reactions of α-pinene to give 4- and 3-membered ring compounds, not hitherto obtained from this source, are described. The study furnished a convenient method of preparation of the optically active cyclobutanone IVa, the title compound which served as the key substrate for all the transformations reported.

Friedel-crafts condensation of ethyl allylmalonate with anisole

Chemical and spectroscopic data, has shown that the major product from Friedel-Crafts condensation of anisole with ethyl allylmalonate, followed by saponification and decarylation is γ-(o-anisyl)valeric acid and not thepara-isomer, as concluded earlier by different groups of workers.

A revised structure for the condensation product of 2-carbethoxycyclopentanone and ethyl cyanoacetate

The condensation product of 2-carbethoxycyclopentanone and ethyl cyanoacetate is ethyl 2-carbethoxycyclopentylidene cyanoacetate (IIa) and not the one described by Kon and Nanji. Similarly, 2-carbomethoxycyclopentanone and methyl cyanoacetate yield methyl 2-carbomethoxycyclopentylidene cyanoacetate (IIb). The by-products obtained in the first reaction are cyclopentylidene cyanoacetate (IV) and the enamine of 2-carbethoxycyclopentanone (VIa).