Degradation of petroleum hydrocarbons in seawater by ionizing radiation

Summary A major concern with leaking petroleum is the environmental contamination by the toxic and water-soluble components such as benzene, toluene and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. All BTX compounds are depressants to the central nervous system. Consequently, BTX are priority pollutants and their occurrence has led to the development of several physical, chemical and biological methods for their removal. The use of nuclear technology for protection and conservation of the environment, by the destruction of toxic organic compounds present in the environmental, drinking water, soils and industrial sewage has been the object of study of several authors in Brazil and in the world. The objective of this paper is to present the preliminary results of the study of contamination of the seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene and xylene, and their removal by the exposure to the ionizing radiation.     

Novel nanostructured materials to develop oxygen-sensitive films for optical sensors

Novel nanostructured materials, such as aluminum oxide (AlOOH), silicon oxide (SiO₂) or zirconium oxide (ZrO₂) embedded into PVA, were investigated as potential matrices to incorporate organometallic compounds (OMCs) for the development of optical oxygen-sensitive sensors which make use of the principle of luminescence quenching.In order to assess the benefits and drawbacks of the nanoporous material, the luminescence quantum yield and the Stern-Volmer constants were investigated and compared with the values shown for the same OMCs solubilized in polymer films (polystyrene). Referred to polymer films, the incorporation of the dyes into nanoporous membranes increased the Stern-Volmer constant by more than a factor of 100. Their response time was less than 1 s and the optode membranes were stable at room temperature for at least 9 months. Sterilization by autoclavation and gamma irradiation resulted in a marginal loss in activity. The photostability and sterilizability of the oxygen-sensitive membranes and the performance of the optodes with respect to of different types of metal oxides are discussed in the paper, as well as the influence of the total pore volume (TPV), the pore diameter (PD), the transparency of the film and the geometry of the pores. The OMCs used in this work were: ETH^T-3003 (tris(4,7-bis(4-octylphenyl)-1,10-phenanthroline) ruthenium(II)), N-926 (bis(2-phenylpyridinyl)-N⁴,N⁴,N⁴′,N⁴′-tetramethyl-(4,4′-diamine-2,2′-bipyridine) iridium(III) chlorate), N-833 (tetrabutylammonium bis(isothiocyanate) bis(2-phenylpyridinyl)-iridium(III)) and N-837 (tetrabutylammonium bis(cyanate) bis(2-phenylpyridinyl)-iridium(III)).     

Spectroscopic investigation of a new hybrid glass formed by the interaction between croconate ion and calcium polyphosphate

In this work, a new organic-inorganic hybrid material has been synthesized by the incorporation of croconate ion into a calcium polyphosphate coacervate. The hybrid so obtained was characterized by means of electronic and vibrational spectroscopies. The material is a homogeneous mixture described by a structural model, which includes helical chains of polyphosphate ions, where the calcium ion occupies the internal vacancies of the structure. The croconate ion appears to be occupying the regions outside the polymeric structure, surrounded by several water molecules. The electronic spectrum of the incorporated material shows a broad band peaking at the same wavelength region (363 nm) observed for the aqueous solution of croconate ion, and manifesting the Jahn-Teller effect as evidenced by the doublet structure of the band. The infrared spectrum is widely dominated by the absorption bands of the polyphosphate ion and the appearance of the carbonyl stretching band at ca. 1550 cm(-1) indicates the presence of croconate ion incorporated in the structure. The Raman spectrum of the material shows several vibrational bands related to the oxocarbon moiety; most of them are shifted in comparison with the free ion. These shifts can be understood in terms of strong hydrogen bonding interactions between water molecules and the oxocarbon moiety. The low temperature methodology proposed here can be well used in the preparation of new phosphate glasses containing organic moieties opening the route to an entirely new class of hybrid glasses.     

Characterisation of cytochrome c unfolding by nano-electrospray ionization time-of-fight and Fourier transform ion cyclotron resonance mass spectrometry

Protein charge-state distributions (CSDs) in electrospray-ionization mass spectrometry (ESI-MS) represent a sensitive tool to probe different conformational states. We describe here the effect of trifluoroethanol (TFE) on cytochrome c equilibrium unfolding at different pH by nano-ESI-MS. While even low concentrations of TFE destabilize the protein native structure at low pH, a TFE content of 2.5%-5% is found to favor cyt c folding at pH approximately 7. Furthermore, we perform comparison of CSDs obtained by time-of-flight (ToF) and Fourier-transform-ion- cyclotron-resonance (FT-ICR) mass analyzers. To this purpose, we analyze spectra of cyt c in the presence of different kind of denaturants. In particular, experiments with 1-propanol suggest that also by FT-ICR-MS, as previously observed on an ESI-ToF instrument, CSDs do not appear to be controlled by the solvent surface tension as predicted by the Rayleigh-charge model. Moreover, there is general good agreement in conformational effects revealed by the different instruments under several buffer conditions. Nevertheless, the ToF instrument appears to discriminate better between unfolded and partially unfolded forms.     

Arsenic speciation in chinese seaweeds using HPLC-ICP-MS and HPLC-ES-MS

Three common Chinese edible seaweeds, one brown (Laminaria japonica) and two red (Porphyra crispata and Eucheuma denticulatum), were examined for their total arsenic content. The As species were extracted with yields of 76.4, 69.8 and 25.0%, respectively. Anion-exchange and cation-exchange high-performance liquid chromatography (HPLC) in combination with inductively coupled plasma mass spectrometry (ICP-MS) were used for the separation of the different arsenic species in two of the three seaweed extracts (Laminaria and Porphyra). The main arsenic species in the algal extracts are arseno sugars, although it has been shown that the Laminaria seaweed contains significant amounts of dimethylarsinic acid (DMA). HPLC was coupled with electrospray mass spectrometry (ES-MS) for structural confirmation of the arsenic species. The mass spectrometer settings for the arseno sugars were optimised using standards. The conclusions drawn on the basis of HPLC-ICP-MS were confirmed by the HPLC-ES-MS data. The HPLC-ES-MS method is capable of determining both arseno sugars and DMA in the seaweeds. The unknown compounds seen in the HPLC-ICP-MS chromatogram of Laminaria could not be ascribed to trimethylarsenic oxide or tetramethylarsonium ion.     

Picoline as ligand with antimony trichloride and triiodide adducts

Solid adducts SbX₃·L-pic (X=Cl, I and L=α-, β- and γ-picolines) were synthesized and characterized by elemental analysis, ¹H and ¹³C NMR, IR spectroscopy and thermal analysis. The infrared spectroscopy and the magnetic resonance for ¹H and ¹³C nuclei of these compounds suggest that the ligands coordinate through nitrogen atom. Kinetic studies were accomplished by means of thermogravimetric data, through isothermal and non-isothermal techniques. The best adjusting models for adducts thermal decomposition were R¹ for isothermal and R₁ and R₂ for the non-isothermal methods. The energy of activation values obtained by isothermal method indicate the following orders of thermal stability for adducts: i) SbCl₃·α-pic>SbCl₃·β-pic>SbCl₃·γ-pic and ii) SbI₃·β-pic>SbI₃·γ-pic>SbI₃·α-pic. The activation energy values obtained by non-isothermal were higher than those from isothermal methods, showing the order of stability:iii) SbCl₃·α-pic<SbCl₃·β-pic<SbCl₃·γ-pic and iv) SbI₃·β-pic>SbI₃·α-pic=SbI_3··γ-pic. These obtained data through R₁ model presented the kinetic compensation effect for trichloride adducts, which could be associated to both isothermal and non-isothermal processes. This revised version was published online in August 2006 with corrections to the Cover Date.     

The development of the DIGE system: 2D fluorescence difference gel analysis technology

Two-dimensional (2D) gel electrophoresis is a powerful technique enabling simultaneous visualization of relatively large portions of the proteome. However, the well documented issues of variation and lack of sensitivity and quantitative capabilities of existing labeling reagents, has limited the use of this technique as a quantitative tool. Two-dimensional difference gel electrophoresis (2D DIGE) builds on this technique by adding a highly accurate quantitative dimension. 2D DIGE enables multiple protein extracts to be separated on the same 2D gel. This is made possible by labeling of each extract using spectrally resolvable, size and charge-matched fluorescent dyes known as CyDye DIGE fluors. 2D DIGE involves use of a reference sample, known as an internal standard, which comprises equal amounts of all biological samples in the experiment. Including the internal standard on each gel in the experiment with the individual biological samples means that the abundance of each protein spot on a gel can be measured relative (i.e. as a ratio) to its corresponding spot in the internal standard present on the same gel. Ettan DIGE is the system of technologies that has been optimized to fully benefit from the advantages provided by 2D DIGE.Cy, CyDye, DeCyder, Ettan, ImageMaster and Typhoon are trademarks of Amersham Biosciences Limited. Amersham and Amersham Biosciences are trademarks of Amersham plc.     

Determination of Diazepam in Human Plasma by Solid-Phase Microextraction and Capillary Gas Chromatography-Mass Spectrometry

A simple, sensitive, and reproducible solid-phase microextraction and capillary gas chromatography-mass spectrometry (SPME-GC-MS) method for determination of diazepam in human plasma is described. The optimum conditions for the SPME procedure were as following: direct extraction mode with a polydimethylsiloxane (PDMS) fiber (100 μm film thickness), 250 μL of sample plasma matrix modified with a solution containing sodium chloride (10% weight by volume) and 4.25 mL of a phosphate buffer solution (0.1mol L⁻¹, pH 6.9), extraction temperature 55°C under a magnetic stirring rate of 2500 rpm for 30 min, followed by the drug thermal desorption (250°C) in a GC injection port for 10 min. The limit of quantification of diazepam in plasma was 10.0 ng mL⁻¹, with a coefficient of variation lower than 14.0% and linearity from 10.0 to 1000.0 ng mL⁻¹, which allows diazepam analyses from sub to therapeutic levels.     

A universal branching set for 4-dimensional manifolds

In this work, a universal branching set K for orientable4 -manifolds, such that