Development and characterization of concentric capillary nebulizer used in inductively coupled plasma analysis /

A simple, low-cost concentric capillary nebulizer (CCN) was developed and evaluated for ICP spectrometry. The CCN could be operated at sample uptake rates of 0.050-1.00 ml min'^ and under oscillating and non-oscillating conditions. Aerosol characteristics for the CCN were studied using a laser Fraunhofter diffraction analyzer. Solvent transport efficiencies and transport rates, detection limits, and short- and long-term stabilities were evaluated for the CCN with a modified cyclonic spray chamber at different sample uptake rates. The Mg II (280.2nm)/l\/lg 1(285.2nm) ratio was used for matrix effect studies. Results were compared to those with conventional nebulizers, a cross-flow nebulizer with a Scott-type spray chamber, a GemCone nebulizer with a cyclonic spray chamber, and a Meinhard TR-30-K3 concentric nebulizer with a cyclonic spray chamber. Transport efficiencies of up to 57% were obtained for the CCN. For the elements tested, short- and long-term precisions and detection limits obtained with the CCN at 0.050-0.500 ml min'^ are similar to, or better than, those obtained on the same instrument using the conventional nebulizers (at 1.0 ml min'^). The depressive and enhancement effects of easily ionizable element Na, sulfuric acid, and dodecylamine surfactant on analyte signals with the CCN are similar to, or better than, those obtained with the conventional nebulizers. However, capillary clog was observed when the sample solution with high dissolved solids was nebulized for more than 40 min. The effects of data acquisition and data processing on detection limits were studied using inductively coupled plasma-atomic emission spectrometry. The study examined the effects of different detection limit approaches, the effects of data integration modes, the effects of regression modes, the effects of the standard concentration range and the number of standards, the effects of sample uptake rate, and the effect of Integration time. All the experiments followed the same protocols. Three detection limit approaches were examined, lUPAC method, the residual standard deviation (RSD), and the signal-to-background ratio and relative standard deviation of the background (SBR-RSDB). The study demonstrated that the different approaches, the integration modes, the regression methods, and the sample uptake rates can have an effect on detection limits. The study also showed that the different approaches give different detection limits and some methods (for example, RSD) are susceptible to the quality of calibration curves. Multicomponents spectral fitting (MSF) gave the best results among these three integration modes, peak height, peak area, and MSF. Weighted least squares method showed the ability to obtain better quality calibration curves. Although an effect of the number of standards on detection limits was not observed, multiple standards are recommended because they provide more reliable calibration curves. An increase of sample uptake rate and integration time could improve detection limits. However, an improvement with increased integration time on detection limits was not observed because the auto integration mode was used.

Analyse du métabolisme du soufre de la bactérie autotrophique acidophile Acidithiobacillus thiooxidans ATCC 19377

Les impacts environnementaux dues à l'extraction minière sont considérables. C'est l'action des microorganismes, en utilisant leur métabolisme du soufre sur les déchets miniers, qui engendre les plus grands défis. Jusqu'à présent, peu de recherches ont été effectués sur les microorganismes environnementaux pour la compréhension globale de l'action du métabolisme du soufre dans une optique de prévention et de rémédiation des impacts environnementaux de l'extraction minière. Dans cette étude, nous avons étudié une bactérie environnementale, Acidithiobacillus thiooxidans, dans le but de comprendre le métabolisme du soufre selon le milieu de culture et le niveau d'acidité du milieu. Nous avons utilisé la transcriptomique à haut débit, RNA-seq, en association avec des techniques de biogéochimie et de microscopie à électrons pour déterminer l'expression des gènes codants les enzymes du métabolisme du soufre. Nous avons trouvé que l'expression des gènes des enzymes du métabolisme du soufre chez ce microorganisme sont dépendantes du milieu, de la phase de croissance et du niveau d'acidité présent dans le milieu. De plus, les analyses biogéochimiques montrent la présence de composés de soufre réduits et d'acide sulfurique dans le milieu. Finalement, une analyse par microscopie électronique révèle que la bactérie emmagasine des réserves de soufre dans son cytoplasme. Ces résultats permettent une meilleure compréhension de son métabolisme et nous rapprochent de la possibilité de développer une technique de prédiction des réactions ayant le potentiel de causer des impacts environnementaux dus à l'extraction minière.

Synergistic solvent extraction of Thorium(IV) and Uranium(VI) with β-diketones in presence of oxo-donors

The thesis entitled “Synergistic solvent extraction of Thorium(IV) and Uranium(VI) with β-diketones in presence of oxo-donors” embodies the results of the investigations carried out on the extraction of thorium(IV) an uranium(VI) with heterocyclic β-diketones in the presence and absence of various macrocyclic ligands and neutral organophosphorus extractants. The objective of this work is to generate the knowledge base to achieve better selectivity between thorium(IV) and uranium(VI) by understanding the interactions of crown ethers or neutral organophosphorus extractants with metal-heterocyclic β-diketonate complexes. Para-substituted 1-phenyl-3-methyl-4-aroyl-5-pyrazolones, namely,1-phenyl-3-methyl-4-(4-fluorobenzoyl)-5-pyrazolone (HPMFBP) and 1-phenyl-3-methyl-4-(4-toluoyl)-5-pyrazolone (HPMTP) were synthesized and characterized by elemental analysis, IR and H NMR spectral data. The synthesized ligands have been utilized for the extraction of thorium(IV) and uranium(VI) from nitric acid solutions in the presence and absence of various crown ethers. Thorium(IV) and uranium(VI) complexes with HPMPP(1-Phenyl-3-methyl-4-pivaloyl-5-pyrazolone) and neutral organophosphorus extractants were synthesized and characterized by IR and P NMR spectral data to further understand the interactions of neutral organophosphorus extractants with metal-chelates. Solid complexes of thorium(IV) and uranium(VI) with para-substituted 4-aroyl-5-isoxazolones and crown ethers were isolated and characterized by various spectroscopic techniques to further clarify the nature of the extracted complexes.

Synthesis And Reactions Of Pyrazoldouinoxalines

The present work reports the synthesis of 2-ary1—3—oxo-3—pyrazolino[3,4-b]quinoxalines for the first time. These compounds have been prepared by the reaction of ethyl 2-chloroquinoxaline—3—carboxylate with different phenylhydrazines. 2-Aryl—3-oxo—3—pyrazolino[3,4—b]quinoxalines are generally light yellow in either neutral or acid solutions but changed the colour to deep violet or green in basic media. The change in colour appears to be sharp and therefore these compounds may be used as acid base indicators. Their UV absorption maxima under acidic and basic media are also very different. However, the actual conditions under which these compounds may be used as indicators have not been worked out. The synthesis and reactions of a new heterocyclic system, lH—l,5—benzodiazepino[2,3—b]quinoxaline is also reported here. This novel nitrogen heterocycke was prepared by the condensation of ethyl 2-chloroquinoxaline-3—carboxylate with o-phenylene diamine and subsequent manipulationsa to give the parent compound. Several derivatives which are expected tx> have valuable biological properties have also beenlreported. The structures of all new compounds have been established by elemental analysis and also by analysing their spectral data smch as ultraviolet, infrared, nuclear magnetic resonance and mass spectrometry. Compounds obtained from this work will be submitted for screening their biological properties.

Sulfation of genistein alters its antioxidant properties and its effect on platelet aggregation and monocyte and endothelial function

Soy isoflavones have been extensively studied because of their possible benefits to human health. Genistein, the major isoflavone aglycone, has received most attention; however, it undergoes extensive metabolism (e.g. conjugation with sulfuric acid) in the gut and liver, which may affect its biological proper-ties. This study investigated the antioxidant activity and free radical-scavenging properties of genistein, genistein-4'-sulfate and genistein-4'-7-disulfate as well as their effect on platelet aggregation and monocyte and endothelial function. Electron spin resonance spectroscopy (ESR) and spin trapping data and other standard antioxidant assays indicated that genistein is a relatively weak antioxidant compared to quercetin and that its sulfated metabolites are even less effective. Furthermore, genistein-4'-sulfate was less potent than genistem, and genistein-4'-7-disulfate even less potent, at inhibiting collagen-induced platelet aggregation, nitric oxide (NO) production by macrophages, and secretion by primary human endothelial cells of monocyte chemoattractant protein 1 (MCP-1), intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1). The current data suggest that sulfation of genistein, with the associated loss of hydroxyl groups, decreases its antioxidant activity and its effect on platelet aggregation, inflammation, cell adhesion and chemotaxis. (C) 2004 Elsevier B.V All rights reserved.

An investigation into the extraction of americium(III), lanthanides and D-block metals by 6,6 '-bis-(5,6-dipentyl-[1,2,4]triazin-3-yl)-[2,2 ']bipyridinyl(C-5-BTBP)

The tetradentate ligand (C-5-BTBP) was able to extract americium(III) selectively from nitric acid. In octanol/kerosene the distribution ratios suggest that stripping will be possible. C-5-BTBP has unusual properties and potentially offers a means of separating metals, which otherwise are difficult to separate. For example C-5-BTBP has the potential to separate paliadium(II) from a mixture containing rhodium(III) and ruthenium(H) nitrosyl. In addition, C-5-BTBP has the potential to remove traces of cadmium from effluent or from solutions of other metals contaminated with cadmium. C-5-BTBP has potential as a reagent for the separation of americium(III) from solutions contaminated with iron(III) and nickel(II), hence offering a means of concentrating americium(III) for analytical purposes from nitric acid solutions containing high concentrations of iron(III) or nickel(II).

Purification and molecular cloning of antimicrobial peptides from Scots pine seedlings

A novel protocol for rapid and efficient purification of antimicrobial peptides from plant seedlings has been developed. Two peptides with antimicrobial activity, designated p1 and p2, were purified nearly to homogeneity from Scots pine seedlings by a combination of sulfuric acid extraction, ammonium sulfate precipitation, heat-inactivation and ion-exchange chromatography on phosphocellulose. Purified proteins had molecular masses of 11 kDa (p1) and 5.8 kDa (p2) and were identified by mass spectrometry as defensin and lipid-transfer protein, respectively. We demonstrated their growth inhibitory effects against a group of phytopathogenic fungi. Furthermore, we report for the first time molecular cloning and characterization of defensin I cDNA from Scots pine. A cDNA expression library from 7 days Scots pine seedlings was generated and used to isolate a cDNA clone corresponding to Scots pine defensin, termed PsDef1. The full-length coding sequence of PsDef1 is 252 bp in length and has an open reading frame capable to encode a protein of 83 amino residues. The deduced sequence has the typical features of plant defensins, including an endoplasmic reticulum signal sequence of 33 aa, followed by a characteristic defensin domain of 50 amino acids representing its active form. The calculated molecular weight of the mature form of PsDef1 is 5601.6 Da, which correlates well with the results of SDS-PAGE analysis. Finally, the antimicrobial properties of PsDef1 against a panel of fungi and bacteria define it as a member of the morphogenic group of plant defensins. (C) 2009 Elsevier Inc. All rights reserved.

Sulfation of genistein alters its antioxidant properties and its effect on platelet aggregation and monocyte and endothelial function

Soy isoflavones have been extensively studied because of their possible benefits to human health. Genistein, the major isoflavone aglycone, has received most attention; however, it undergoes extensive metabolism (e.g. conjugation with sulfuric acid) in the gut and liver, which may affect its biological proper-ties. This study investigated the antioxidant activity and free radical-scavenging properties of genistein, genistein-4'-sulfate and genistein-4'-7-disulfate as well as their effect on platelet aggregation and monocyte and endothelial function. Electron spin resonance spectroscopy (ESR) and spin trapping data and other standard antioxidant assays indicated that genistein is a relatively weak antioxidant compared to quercetin and that its sulfated metabolites are even less effective. Furthermore, genistein-4'-sulfate was less potent than genistem, and genistein-4'-7-disulfate even less potent, at inhibiting collagen-induced platelet aggregation, nitric oxide (NO) production by macrophages, and secretion by primary human endothelial cells of monocyte chemoattractant protein 1 (MCP-1), intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1). The current data suggest that sulfation of genistein, with the associated loss of hydroxyl groups, decreases its antioxidant activity and its effect on platelet aggregation, inflammation, cell adhesion and chemotaxis. (C) 2004 Elsevier B.V All rights reserved.

Miscibility studies of the blends of chitosan with some cellulose ethers

The polymeric films have been prepared based on blends of chitosan with two cellulose ethers-hydroxypropylmethylcellulose and methylcellulose by casting from acetic acid solutions. The films were transparent and brittle in a dry state but an immersion of the samples in deionized water for over 24 h leads to their disintegration or partial dissolution. The miscibility of the polymers in the blends has been assessed by infrared spectroscopy, wide-angle X-ray diffraction, scanning electron microscopy and thermal gravimetric analysis. It was shown that although weak hydrogen bonding exists between the polymer functional groups the blends are not fully miscible in a dry state. (c) 2005 Elsevier Ltd. All rights reserved.

Highly efficient separation of actinides from lanthanides by a phenanthroline-derived bis-triazine ligand

The synthesis, lanthanide complexation, and solvent ex- traction of actinide(III) and lanthanide(III) radiotracers from nitric acid solutions by a phenanthroline-derived quadridentate bis-triazine ligand are described. The ligand separates Am(III) and Cm(III) from the lanthanides with remarkably high efficiency, high selectivity, and fast extraction kinetics compared to its 2,2'-bipyridine counterpart. Structures of the 1:2 bis-complexes of the ligand with Eu(III) and Yb(III) were elucidated by X-ray crystallography and force field calculations, respec-tively. The Eu(III) bis-complex is the first 1:2 bis-complex of a quadridentate bis-triazine ligand to be characterized by crystallography. The faster rates of extraction were verified by kinetics measurements using the rotating membrane cell technique in several diluents. The improved kinetics of metal ion extraction are related to the higher surface activity of the ligand at the phase interface. The improvement in the ligand's properties on replacing the bipyridine unit with a phenanthroline unit far exceeds what was anticipated based on ligand design alone.

The separation of americium(III) from europium(III) by two new 6,6'-bistriazinyl-2,2'-bipyridines in different diluents

The synthesis and extraction of americium(III) and europium(III) from aqueous nitric acid solutions by the new BTBP ligands 6,6’-bis(5,5,7,7- tetramethyl-5,7-dihydrofuro[3,4-e]-1,2,4-triazin-3-yl)-2,2’-bipyridine (Cy5-O-Me4-BTBP), and 6,6’-bis(5,5,7,7-tetramethyl-5,7-dihydrothieno[3,4-e]-1,2,4-triazin-3-yl)- 2,2’-bipyridine (Cy5-S-Me4-BTBP) is described. The affinity for Am(III) and the selectivity for Am(III) over Eu(III) of Cy5-S-Me4-BTBP were generally higher than for Cy5-O-Me4-BTBP. For both ligands, the extraction of Am(III) and Eu(III) from 3 M HNO3 into 3 mM organic solutions varied with the diluent used. The highest distribution ratios and separation factors observed were in cyclohexanone and 2-methylcyclohexanone, respectively. For Cy5-S-Me4-BTBP, there is a strong correlation between the distribution ratio for Am(III) and the permittivity of the diluent used. With 1-octanol as the diluent, low distribution ratios (D(Am) < 1) were observed for Cy5-S-Me4-BTBP although this ligand extracts Am(III) selectively (SFAm/Eu = 16-46 from 1-4 M HNO3). For Cy5-S-Me4-BTBP, Am(III) is extracted as the disolvate. The distribution ratios for Am(III), and the separation factors for Am(III) over Eu(III) are both significantly higher for CyMe4-BTBP than they are for Cy5-O-Me4-BTBP and Cy5-S-Me4-BTBP in cyclohexanone. Changing the diluent from cyclohexanone to 2-methylcyclohexanone leads to a decrease in D(Am) but an increase in SFAm/Eu for Cy5-S-Me4-BTBP.

π-dimerization of pleiadiene radical cations at low temperatures revealed by UV–vis spectroelectrochemistry and quantum theory

One-electron oxidation of the non-alternant polycyclic aromatic hydrocarbon pleiadiene and related cyclohepta[ c,d]pyrene and cyclohepta[c,d]fluoranthene in THF produces corresponding radical cations detectable in the temperature range of 293–263 K only on the subsecond time scale of cyclic voltammetry. Although the EPR-active red-coloured pleiadiene radical cation is stable according to the literature in concentrated sulfuric acid, spectroelectrochemical measurements reported in this study provide convincing evidence for its facile conversion into the green-coloured, formally closed shell and, hence, EPRsilent π-bound dimer dication stable in THF at 253 K. The unexpected formation of the thermally unstable dimeric product featuring a characteristic intense low-energy absorption band at 673 nm (1.84 eV; logεmax=4.0) is substantiated by ab initio calculations on the parent pleiadiene molecule and the PF6 − salts of the corresponding radical cation and dimer dication. The latter is stabilized with respect to the radical cation by 14.40 kcal mol−1 (DFT B3LYP) [37.64 kcal mol−1 (CASPT2/DFT B3LYP)]. An excellent match has been obtained between the experimental and TDDFT- calculated UV–vis spectra of the PF6 − salt of the pleiadiene dimer dication, considering solvent (THF) effects.

2D hexagonal mesoporous platinum films exhibiting biaxial, in-plane pore alignment

The synthesis of 2D hexagonal mesoporous platinum films with biaxial, in-plane pore alignment is demonstrated by electrodeposition through an aligned lyotropic liquid crystal templating phase. Shear force is used to align a hexagonal lyotropic liquid crystalline templating phase of an inexpensive and a commercially available surfactant, C16EO10, at the surface of an electrode. Electrodeposition and subsequent characterisation of the films produced shows that the orientation and alignment of the phase is transferred to the deposited material. Transmission electron microscopy confirms the expected nanostructure of the films, whilst transmission and grazing incidence small angle X-ray scattering analysis confirms biaxial, in plane alignment of the pore structure. In addition further electrochemical studies in dilute sulfuric acid and methanol show that the pores are accessible to electrolyte solution as indicated by a large current flow; the modified electrode therefore has a high surface area, that catalyses methanol oxidation, and the pores have a very large aspect ratio (of theoretical maximum 2 × 105). Films with such aligned mesoporosity will advance the field of nanotechnology where the control of pore structure is paramount. The method reported is sufficiently generic to be used to control the structure and order of many materials, thus increasing the potential for the development of a wide range of novel electronic and optical devices.

Complexation of lanthanides, actinides and transition metal cations with a 6-(1,2,4-triazin-3-yl)-2,2′:6′,2′′-terpyridine ligand: implications for actinide(III)/lanthanide(III) partitioning

The quadridentate N-heterocyclic ligand 6-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin- 3-yl)-2,2′ : 6′,2′′-terpyridine (CyMe4-hemi-BTBP) has been synthesized and its interactions with Am(III),U(VI), Ln(III) and some transition metal cations have been evaluated by X-ray crystallographic analysis, Am(III)/Eu(III) solvent extraction experiments, UVabsorption spectrophotometry, NMR studies and ESI-MS. Structures of 1 : 1 complexes with Eu(III), Ce(III) and the linear uranyl (UO2 2+) ion were obtained by X-ray crystallographic analysis, and they showed similar coordination behavior to related BTBP complexes. In methanol, the stability constants of the Ln(III) complexes are slightly lower than those of the analogous quadridentate bis-triazine BTBP ligands, while the stability constant for the Yb(III)complex is higher. 1H NMR titrations and ESI-MS with lanthanide nitrates showed that the ligand forms only 1 : 1 complexes with Eu(III), Ce(III) and Yb(III), while both 1 : 1 and 1 : 2 complexes were formed with La(III) and Y(III) in acetonitrile. A mixture of isomeric chiral 2 : 2 helical complexes was formed with Cu(I), with a slight preference (1.4 : 1) for a single directional isomer. In contrast, a 1 : 1 complex was observed with the larger Ag(I) ion. The ligand was unable to extract Am(III) or Eu(III) from nitric acid solutions into 1-octanol, except in the presence of a synergist at low acidity. The results show that the presence of two outer 1,2,4-triazine rings is required for the efficient extraction and separation of An(III)from Ln(III) by quadridentate N-donor ligands.

Influence of diluent alkyl substitution on the extraction of Am(III) and Eu(III) by a 6,6'-bis(1,2,4-triazinyl)-2,2'-bipyridine ligand dissolved in alkylated cyclohexanone diluents

Several alkylated cyclohexanones were investigated as potential diluents for the selective extraction of Am(III) and Eu(III) from nitric acid solutions by the CyMe4-BTBP ligand. No significant extraction of either of the metal ions was observed for these diluents themselves. In the extractions from 1 M HNO3, 3-methylcyclohexanone and 4-methylcyclohexanone gave comparable results to cyclohexanone whereas in the extractions from 4 M HNO3, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone all gave superior results. For the monomethylated diluents, DAm and SFAm/Eu decreased in the order of alkyl substitution 2 > 4 ~ 3. However, alkyl substitution of cyclohexanone significantly slows down the extraction kinetics compared to cyclohexanone, and the position of alkyl substitution was found to play an important role in the solvents properties. 3-Methylcyclohexanone was identified as the most promising of the diluents.