Isolation of thermo-stable and solvent-tolerant Bacillus sp. lipase for the production of biodiesel

This study presents the production of biodiesel from algae oil by transesterification using thermophilic microorganism. The microorganism used in this study was isolated from the soil sample obtained near the furnace. The organism was identified as Bacillus sp., and the lipase obtained was purified by ammonium sulfate precipitation and ion exchange chromatography leading to 8.6-fold purification and 13% recovery. Molecular weight of the enzyme was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it was found to be 45 kDa. The effect of pH, temperature, and solvent addition on lipase activity was investigated. The enzyme showed maximum activity at 55 °C and at pH 7 and was also found to be highly active in the presence of organic solvents such as hexane and t-butanol. The isolated lipase was successfully used for the production of biodiesel. The transesterification activity of the isolated lipase showed 76% of fatty acid methyl esters yield in 40 h, which indicated that this enzyme can be used as a potential biocatalyst for the biodiesel production.     

Nanocrystalline tin compounds/graphene nanocomposite electrodes as anode for lithium-ion battery

Nanocrystalline tin (Sn) compounds such as SnO₂, SnS₂, SnS, and graphene nanocomposites were prepared using hydrothermal method. The X-ray diffraction (XRD) pattern of the prepared nanocomposite reveals the presence of tetragonal SnO₂, hexagonal SnS₂, and orthorhombic SnS crystalline structure in the SnO₂/graphene nanosheets (GNS), SnS₂/GNS, and SnS/GNS nanocomposites, respectively. Raman spectroscopic studies of the nanocomposites confirm the existence of graphene in the nanocomposites. The transmission electron microscopy (TEM) images of the nanocomposites revealed the formation of homogeneous nanocrystalline SnO₂, SnS_2, and SnS particle. The weight ratio of graphene and Sn compound in the nanocomposite was estimated using thermogravimetric (TG) analysis. The cyclic voltammetry experiment shows the irreversible formation of Li₂O and Li₂S, and reversible lithium-ion (Li-ion) storage in Sn and GNS. The charge–discharge profile of the nanocomposite electrodes indicates the high capacity for the Li-ion storage, and the cycling study indicates the fast capacity fading due to the poor electrical conductivity of the nanocomposite electrodes. Hence, the ratio of Sn compounds (SnO₂) and GNS have been altered. Among the examined SnO₂:GNS nanocomposites ratios (35:65, 50:50, and 80:20), the nanocomposite 50:50wt% shows high Li-ion storage capacity (400 mAh/g after 25 cycles) and good cyclability. Thus, it is necessary to modify GNS and Sn compound composition in the nanocomposite to achieve good cyclability.     

1‐Alkyl‐1H‐imidazole‐Based Dipolar Organic Compounds for Dye‐Sensitized Solar Cells

A series of donor–π–acceptor‐type organic dyes based on 1‐alkyl‐1H‐imidazole spacers 1 , 2 , 3 , 4 , 5 have been developed and characterized. The two electron donors are at positions 4 and 5 of the imidazole, while the electron‐accepting cyanoacrylic acid is incorporated at position 2 by a spacer‐containing heteroaromatic rings, such as thiophene and thiazole. Detailed investigation on the relationship between the structure, spectral and electrochemical properties, and performance of DSSC is described here. Dye‐sensitized solar cells (DSSCs) using dyes as the sensitizers exhibit good efficiencies, ranging from 3.06 to 6.35 %, which reached 42–87 % with respect to that of N719‐based device (7.33 %) fabricated and measured under similar conditions. Time‐dependent density functional theory (TDDFT) calculations have been performed on the dyes, and the results show that both electron donors can contribute to electron injection upon photo‐excitation, either directly or indirectly by internal conversion to the lowest excited state.     

Synthesis, spectral characterization and catalytic studies of new ruthenium(II) chalcone thiosemicarbazone complexes

A series of new hexa-coordinated ruthenium(II) complexes of the type [Ru(CO)(EPh₃)(B)(L)] (E = P or As; B = PPh₃, AsPh₃ or Py; L = chalcone thiosemicarbazone) have been prepared by reacting [RuHCl(CO)(EPh₃)₂(B)] (E = P or As; B = PPh₃, AsPh₃ or Py) with chalcone thiosemicarbazones in benzene under reflux. The new complexes have been characterized by analytical and spectroscopic (IR, UV-vis, ¹H, ³¹P and ¹³C NMR) methods. On the basis of data obtained, an octahedral structure was assigned for all of the complexes. The chalcone thiosemicarbazones behave as dianionic tridentate O, N, S donors and coordinate to ruthenium via the phenolic oxygen of chalcone, the imine nitrogen of thiosemicarbazone and thienol sulfur. The new complexes exhibit catalytic activity for the oxidation of primary and secondary alcohols to their corresponding aldehydes and ketones and they were also found to be efficient catalysts for the transfer hydrogenation of carbonyl compounds.     

PVT properties of UNEX/HCCD-PEG diluent phenyl trifluoromethyl sulfone (FS-13) and experimental measurement of vapour pressure in 283.15–363.15?K range

Phenyl trifluoromethyl sulfone (FS-13) is a polar diluent, proposed in literature as an alternate to nitrobenzene, in UNEX/HCCD-PEG processes for better physical properties. Its PVT properties and accurate expression for estimation of its vapour pressure are not available in the literature. Recently PVT properties of FS-13 were estimated by authors and its vapour pressure was experimentally measured at temperatures ranging from 263.15 to 363.15 K. In this paper, results of these studies are presented.     

Efficient oxidation of hydrazine using amine-functionalized cobalt and nickel porphyrin-modified electrodes

The meso-tetra(para-aminophenyl) porphyrinatocobalt(II) (Co(II)MTpAP) and meso-tetra(para-aminophenyl)porphyrinatonickel(II) (Ni(II)MTpAP) were self-assembled on a glassy carbon electrode (GCE) and were utilized for the oxidation of hydrazine. The oxidation of hydrazine at the self-assembled monolayers (SAMs) of Co(II)MTpAP and Ni(II)MTpAP occurred at ?0.20 and 0.42 V, respectively. When compared to the SAM of Ni(II)MTpAP, Co(II)MTpAP SAM not only decreased the overpotential of hydrazine oxidation but also enormously increased its current. The oxidation of hydrazine was influenced by pH. While increasing the pH, the oxidation potential of hydrazine was shifted towards a less positive potential. Further, an inverted shape cyclic voltammogram (CV) was observed for the oxidation of hydrazine at Co(II)MTpAP-modified GCE, whereas a normal CV curve was observed at Ni(II)MTpAP-modified GCE. The appearance of the inverted shape peak for hydrazine oxidation at the SAM of Co(II)MTpAP is due to the oxidation of axially ligated hydrazine molecules during the reverse potential scan. The hydrazine oxidation was also performed at amine-functionalized cobalt and nickel phthalocyanine-modified electrodes in order to study the influence of a macrocyclic ring. Irrespective of the macrocyclic ring, an inverted shape CV was observed at cobalt phthalocyanine-modified electrode.     

Effect of deprotection extent on swelling and dissolution regimes of thin polymer films

The response of unentangled polymer thin films to aqueous hydroxide solutions is measured as a function of increasing weakly acidic methacrylic acid comonomer content produced by an in situ reaction-diffusion process. Quartz crystal microbalance with energy dissipation and Fourier transform infrared spectroscopy measurements are used to identify four regimes: (I) nonswelling, (II) quasiequilibrium swelling, (III) swelling coupled with partial film dissolution, and (IV) film dissolution. These regimes result from chemical heterogeneity in local composition of the polymer film. The acid-catalyzed deprotection of a hydrophobic group to the methacrylic acid tends to increase the hydrophilic domain size within the film. This nanoscale structure swells in aqueous base by ionization of the methacrylic acid groups. The swollen film stability, however, is determined by the hydrophobic matrix that can act as physical cross-links to prevent dissolution of the polyelectrolyte chains. These observations challenge current models of photoresist film dissolution that do not include the effects of swelling and partial film dissolution on image quality.     

Ruthenium(II) chalconate complexes: Synthesis, characterization, catalytic, and biological studies

A series of new hexa-coordinated ruthenium(II) carbonyl complexes of the type [RuCl(CO)(EPh₃)(B)(L)] (E = P or As; B = PPh₃, AsPh₃ or Py; L = 2′-hydroxychalcones) have been prepared by reacting [RuHCl(CO)(EPh₃)₂(B)] (E = P or As; B = PPh₃, AsPh₃ or Py) with 2′-hydroxychalcones in benzene under reflux. The new complexes have been characterized by analytical and spectral (IR, electronic, ¹H, ³¹P and ¹³C NMR) data. Based on the above data, an octahedral structure has been assigned for all the complexes. The new complexes exhibit catalytic activity for the oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant and also found efficient catalyst in the transfer hydrogenation of ketones. The antifungal properties of the complexes have also been examined and compared with standard Bavistin.