Thorium adsorption by oxidized biochar fibres derived from Luffa cylindrica sponges

Journal of Radioanalytical and Nuclear Chemistry - The present study deals with the preparation of oxidized biochar fibres derived from Luffa cylindrica sponges and the subsequent adsorption of...     

Triterpenic derivatives of Achillea alexandri-regis BORNM. & RUDSKI

Investigation of the aerial parts of Achillea alexandri-regis led to the identification of 19 chemical constituents: twelve 3-O-fatty acid esters of triterpene alcohols arnidiol (1-4), maniladiol (5-8) and 16beta-hydroxylupeol (9-12), alpha-amyrin, beta-amyrin, beta-sitosterol, 3,4-O-dicaffeoyl quinic acid, cinnamic acid, pinoresinol-beta-D-glucoside and rutin. Among them, compounds 3, 4, 8, 11 and 12 are new natural products. The structures of all compounds have been elucidated on the basis of their spectral and chemical data.     

Determination of quinine and quinidine by continuous-flow chemiluminescence

A rapid and precise continuous-flow method is described for the determination of quinine and quinidine (5.00–500 μg ml^?1) which is based on the sensitizing effect of the compounds on the chemiluminescent oxidation of sulphite by cerium(IV). When applied to tablets, the procedure is relatively free from interferences from common excipients. The results obtained for the assay of commercial formulations compared well with those obtained by an official method and demonstrated good accuracy and precision.     

Reactions of indole derivatives with cardioprotective activity with reactive oxygen species. Comparison with melatonin

We have previously reported on the synthesis of novel indole derivatives containing an amine-triazole moiety (1a-d, 2a-c), and their antioxidant activity on in vitro non-enzymatic rat hepatic microsomal lipid peroxidation. Some of the compounds showed protective activity against oxidative injury of ischemic myocardium. In the present paper we investigated the interactions of these derivatives with reactive oxygen species, in order to find a mechanism of their antioxidant capacity and to identify structural characteristics responsible for these properties. These interactions were compared with melatonin, which is also an indole derivative. The antioxidant profiles of the compounds were established by different in vitro protocols as follows: 1) by the interaction of the compounds with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, 2) their scavenging effects on superoxide anions using an enzymic system of xanthine-xanthine oxidase, 3) their inhibitory effects on xanthine oxidase and 4) their ability to scavenge hydroxyl radicals by comparison with dimethyl sulfoxide (DMSO) for *OH. All compounds were found to interact with DPPH, most of them to be superoxide anion scavengers and to be strong hydroxyl radical scavengers. Derivatives 1a and 1d substituted on the nitrogen of the indolic nucleus were found to have better antioxidant properties than the reference compounds used and melatonin.     

Sources and transport of hydrocarbons in the Rhone delta sediments (Northwestern Mediterranean)

Summary To assess sources and transport processes of hydrocarbons in the Rhone delta, superficial sediments were collected near the river mouth and at the limit of the continental shelf in February 85 and September 86. After spiking with perdeuterated standards and isolation of lipids, a normal-phase HPLC step permitted the separation of hydrocarbons in non-aromatics (NAH) and aromatics (PAH), and the fractionation of the latter into sub-groups as a function of the number of aromatic cycles. Analysis of fractions and quantitation of individual compounds were performed by GC and GC/MS. Hydrocarbon concentrations varied from 21.2 to 166.7 g/g for the NAH, and from 1070 to 6363 ng/g for the PAH. Relevant seasonal variations were observed, reflecting quantitative and qualitative fluctuations of inputs. Petrogenic, pyrolytic and natural derived imprints, as well as their respective contributions were evidenced by distribution patterns, values of ratios of characteristic compounds and occurrence of specific components. Pyrolytic inputs were considerably higher in winter, reflecting intense inputs from combustion processes and/or run-off. On the contrary, fossil as well as natural inputs were significantly higher in summer.     

Electrochemical promotion of electronically isolated and dispersed Pt catalysts

In this paper we discuss the first attempts to induce the effect of Electrochemical Promotion or Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA) on highly dispersed catalyst-electrodes systems which can compete in terms of dispersion and surface area with industrial catalysts. Three systems are discussed:

1. Electrochemical promotion of C₂H₄ oxidation on electronically isolated Pt catalysts on Y₂O₃-stabilized-Zirconia (YSZ) where NEMCA is induced via potential application between two terminal Au electrodes also supported on the solid electrolyte (bipolar design).
2. Electrochemical promotion of C₂H₄ oxidation on a finely dispersed Pt catalyst deposited on a Au electrode which is supported on YSZ.
3. Induction of NEMCA during CH₃OH oxidation on Pt without external voltage application by utilizing the potential difference developed between the catalyst and a catalytically inert counter electrode.

In all cases significant non faradaic behavior has been obtained. The underlying catalytic/ electro-catalytic phenomena are discussed together with some of the engineering challenges for potential practical applications.     

Corrole and Porphyrin Amino Acid Conjugates: Synthesis and Physicochemical Properties

A series of conjugates of amino acids with porphyrins and corroles was synthesized. Their self‐assembling ability under defined conditions was investigated by scanning electron microscopy. The morphology and photophysical properties of these molecules were studied by absorption and fluorescence spectroscopy in solid, liquid, and self‐assembled forms. We observed that both corrole and porphyrin conjugated with the l ‐phenylalanine–l ‐phenylalanine peptide to form spherical nanostructures with bathochromic shifts in the emission spectra, indicating the formation of aggregates. These aggregates are characterized by the impressive absorption of light over nearly the whole visible range. The broadening of all bands was particularly strong in the case of corroles. The fluorescence lifetimes of self‐assembled species were longer as compared to the solid‐state form.