A note on best constants in discrete inequalities

In this paper, optimization theory is used for the determination of best constants in certain discrete inequalities. An example is given.     

The characterization of modified silica-alumina catalysts active in the synthesis of picolines

The SiO₂–Al₂O₃ catalyst is modified by promoters like Pb, Cr, Cu. The SiO₂–Al₂O₃ catalyst is also modified using two elements by a simultaneous or stepwise impregnation method. The catalysts are characterized by XRD, IR and ESR techniques, and are useful in the synthesis of picolines.IICT Communication No. 3514, decicated to Dr. A.V. Rama Rao on his 60th birthday.     

Vapor phase acylation of phenol over Hβ, CeHβ and SO42-/ZrO2a

Phenol acylation on Hβ, CeHβ and SO₄ ^2-/ZrO₂ using acetic acid and acetic anhydride as acylating agents is compared in the temperature range 250-400°C. Acetic acid formed phenyl acetate (PA) and o-hydroxy acetophenone (o-HAP) and acetic anhydride formed p-hydroxyacetophenone (p-HAP ) along with PA and o-HAP. The formation of o-HAP and p-HAP, the products of C-acylation of phenol using acetic acid is proposed by studying phenyl acetate conversion on Hb, CeHβ and SO₄ ^2-/ZrO₂. Our studies show that for phenol acylation the most suitable acid site is available on CeHβ. This revised version was published online in June 2006 with corrections to the Cover Date.     

Selective solar photocatalytic oxidation of ethylbenzene on C,N, and S doped TiO<Subscript>2</Subscript>

The liquid-phase photo-oxidation of ethylbenzene (EB) is investigated in solar light with air/O₂/N₂ at atmospheric pressure, in a batch reactor using acetonitrile medium. It is carried out over TiO₂ doped with C, N, and S (TCNS) photocatalyst samples. The photocatalytic oxidation yielded acetophenone (33%) and 1-phenylethanol (21%) at 56% conversion of EB during a 6-h irradiation time. This product distribution indicates that C–H bond activation has occurred only at the alkyl chain. The effects of the EB to water content ratio, amount of photocatalyst and its sustainability, pH, have been studied. It is illustrated that the reaction carried out by this environmentally friendly photocatalysis is truly heterogeneous under mild conditions using solar light and no waste generation. An optimum loading of TCNS5 was observed for the photo-oxidation of EB.     

Development of Methane Decomposition Catalysts for CO<Subscript>x</Subscript> Free Hydrogen

Now-a-days, catalytic decomposition of methane (CDM) into hydrogen and carbon is a promising technique for production of fuel cell grade hydrogen. The Ni based catalysts seems promising particularly for the production of CO_x free H₂ by methane decomposition process. The CDM activity and longevity of the Ni based catalysts are mainly influenced by the amount of Ni and type of support material. In this paper the CDM activity results are correlated with NiO crystallite size, Ni metal surface area and acidity of the catalysts. In case of bimetallic catalysts addition of Cu to Ni catalysts lead to enhance the CDM activity at higher temperature thus resulting in the increased concentration of hydrogen in the outlet stream. Finally, some of the carbon-based catalysts are studied for methane decomposition activity at higher temperature. The surface changes over carbon catalysts with methane decomposition are studied using various characterization techniques.     

Blue light emitting graphene-based materials and their use in generating white light

It has been demonstrated that acid-treated graphene samples as well as reduced graphene oxide show fairly intense blue emission centered around 440 nm. Reduction of graphene oxide can be carried out either chemically or by using different types of radiations. Blue emission from graphene-based materials can be combined with the yellow emission from materials like ZnO to produce white light sources.     

Metabolite identification by data-dependent accurate mass spectrometric analysis at resolving power of 60,000 in external calibration mode using an LTQ/Orbitrap

Performance evaluation of accurate mass measurement by the LTQ/Orbitrap, at a resolving power of 60,000 and in external calibration mode, indicated that the Orbitrap is capable of providing high mass accuracy of <2 ppm for over 24 h post-calibration. This, together with limited trade-off between sensitivity and resolving power plus a wide dynamic range for mass accuracy, suggested that the LTQ/Orbitrap is an ideal analytical tool for structural elucidation of metabolites. The application of the LTQ/Orbitrap to identification of human liver microsomal metabolites of carvedilol was evaluated, using parent mass list triggered data-dependent multiple-stage accurate mass analysis, at a resolving power of 60,000 in external calibration mode. A metabolite identification workflow was developed to utilize chemical formulas from high-resolution accurate mass measurements to confirm structures of product ions of a drug proposed by Mass Frontier, illustrated by identification of structures used to establish lineage of product ions of carvedilol, which later served as a template for identification of its metabolites. A total of 58 in vitro metabolites of carvedilol were detected using 5-ppm mass tolerance filters for theoretical m/z of protonated molecules of predicted metabolites in addition to product ions and neutral mass losses diagnostic of carvedilol. The chemical formulas with unsaturation numbers calculated from the accurate m/z of precursor and product ions can be used to assign, with a high degree of confidence, the structures of metabolites and the sites of metabolism. The mass accuracies obtained for all full scan MS and MSn spectra were <2 ppm. The majority of the metabolites identified agreed with those previously reported except for those that have not been reported before. For example, several glutathione conjugates of carvedilol were reported for the first time, which may explain the reported hepatotoxicity during clinical trials and recent clinical use.