The Composition of Oxygen Functionals Groups at the Surface of Carbon-Based Graphitic Anode

In lithium-ion batteries (LIBs), the quality of a solid electrolyte interphase (SEI) that forms at the electrode/electrolyte interface substantially affects the stability and lifetime of the devices. One of the major determinants of the morphology and properties of SEI is the surface structure and composition of the graphitic anode used. The presence of oxygenated surface groups at the graphitic anode facilitates the formation of SEI at the interface that stabilizes LIBs. A series of DFT calculations reveal that at typical operating conditions (temperature, pH) of LIBs, the (1120) edge facet of graphite anode will be fully oxygenated, while the basal sites remain unsaturated. The oxygen functional groups at the edge sites are comprised of mostly hydroxyl and ketonic groups, with carboxyl and carbonyl groups are present in small amounts. Furthermore, we observe transformation of carbonyl group into ketonic group in the presence of empty surface carbon sites, which further stabilize the graphite surface. Meanwhile, carboxyl groups are more stable when all surface sites within a carboxyl layer are all populated. On the contrary to the edge plane, a small amount of oxygen functional groups may be forced to adsorb on the basal surface upon application of an external potential.

Magnetite Functionalized Nigella Sativa Seeds for the Uptake of Chromium(VI) and Lead(II) Ions from Synthetic Wastewater

The aim of the present study was to utilise pristine and magnetite-sucrose functionalized Nigella Sativa seeds as the adsorbents for the uptake of chromium(VI) and lead(II) ions from synthetic wastewater. Prestine Nigella Sativa seeds were labelled (PNS) and magnetite-sucrose functionalized Nigella Sativa seeds (FNS). The PNS and FNS composites were characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The FTIR analysis of both adsorbents revealed the presence of vibrations assigned to 1749 and 1739 cm-1 (-C=O) for ketonic group for both adsorbents. The amide (-NH) peak was observed at 1533 and 1527 cm-1 on FNS and PNS composites, respectively, whilst the carboxyl group (-COOH) were observed at 1408 cm-1 on both adsorbents. The XRD results of FNS and PNS composites showed a combination of spinel structure and y -Fe2O3 phase confirming the formation of iron oxide. The influence of operational conditions such as initial concentration, temperature, pH, and contact time was determined in batch adsorption system. The kinetic data of Cr(VI) and Pb(II) ions on both adsorbents was described by pseudo-first-order (PFO) model which suggested physisorption process. The sorption rate of Cr(VI) ions was quicker, it attained equilibrium in 20 min, and the rate of Pb(II) ions was slow in 90 min. Freundlich isotherm described the mechanism of Pb(II) ions adsorption on PNS and FNS composites. Langmuir best fitted the uptake of Cr(VI) ions on PNS and FNS. The results for both adsorbents showed that the removal uptake of Pb(II) ions increased when the initial concentration was increased; however, Cr(VI) uptake decreased when the initial concentration increased. The adsorption of Cr(VI) and Pb(II) ions on both adsorbents increased with temperature.

Supercritical fluid infusion of silver into polyimide films of varying chemical composition

Polyimides can be infused with silver complexes by the use of supercritical fluids. Highly reflective polyimide films were formed by infusing (1,5-cyclooctadiene-1,1,1,5,5,5-hexafluoroacetylacetonato)silver(I) [Ag(COD) (HFA)] into a number of polyimides and then thermally curing those films at 300 °C for time intervals between 30 min and 3 h. Reflectivities of the films exhibited strong dependence on the infusion and cure conditions as well as on the type of polyimide used. The highest reflectivity of 67.1% was achieved with a silvered film prepared from 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (BTDA) and oxydianiline (ODA) infused at 5000 psi, 100 °C, for 30 min and cured for 1 h at 300 °C. Reflectivities of silvered surfaces of other polyimides investigated varied from 39% to 61%. A strong correlation between the presence of a ketonic group in the polyimide structure and the formation of mirror surfaces was detected.

The role of 6-phosphogluconate dehydrogenase in Rhizobium

A nicotinamide adenine dinucleotide (NAD) linked 6-phosphogluconate (6-PG) dehydrogenase has been detected in Rhizobium. The enzyme activity is similar in both slow- and fast-growing rhizobia. The nicotinamide adenine dinucleotide phosphate (NADP) dependent 6-PG dehydrogenase was detected only in the fast growers and was more than twice as active as the NAD-linked enzyme. Partial characterization of the products of 6-PG oxidation in Rhizobium suggests that the NADP-linked enzyme is the decarboxylating enzyme of the pentose phosphate (PP) pathway (EC 1.1.1.44) whereas a phosphorylated six-carbon compound, containing ketonic group(s), is the product of the oxidation catalyzed by the NAD-linked enzyme.

Novel biotransformation of menthone by microbial strains and vermicompost microbial consortium

The aim of the study was to evaluate the ability of Trichoderma harzianum and Pseudomonas fluorescence and vermicompost microbial consortium to biotransform the monoterpene menthone. The different microbial transformation was carried out in different media including the control flask. Samples of different cultures were taken after every 24 hours, extracted with n-hexane and analysed by GC and GC-MS. The chemical structure of the bio transformed products were identified by GC and GC-MS. All the microbial strains led to the decomposition of menthone with time. The most valuable transformation was the production of menthol by vermicompost microbial strain. The obtained data indicated that vermicompost microbial consortium is a good biocatalyst to convert the ketonic group into hydroxyl group and showed the importance of various microbial strains in the biotransformation of the menthone.

THE ALKALOIDS OF SENECIO SPECIES: I. THE NECINES AND NECIC ACIDS FROM S. RETRORSUS AND S. JACOBAEA

A new alkaloid, retrorsine, has been isolated from Senecio retrorsus of South African origin. Analysis of the free base and its methiodide together with its hydrolytic products point to the empirical formula, C18H25O6N. Hydrolysis yields a new base, C8H13O2N, termed retronecine together with an acid, retronecic acid, isolated as the monolactone, C10H14O5. The base is tertiary, contains one hydroxyl (benzoyl derivative) and probably a ketonic group. The preparation of the di-p-phenylphenacyl derivative of the acid proves its dibasicity. The alkaloid, jacobine, from S. jacobaea has been isolated in a state of purity and probably has the empirical formula C18H23O5N, although this is only partly confirmed by analysis of the hydrolytic fragments. The necine derived from jacobine is shown to be identical with retronecine.An examination of S. aureus failed to show the presence of an alkaloid in tractable amounts. A system of simplified nomenclature to designate the Senecio alkaloids and their hydrolytic products is suggested.