Preparation of zinc-oxide and zinc-sulfide powders by controlled precipitation from aqueous-solution

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Interaction of Ruthenium(II)-dipyridophenazine Complexes with CT-DNA: Effects of the Polythioether Ancillary Ligands

The complexes [Ru([9]aneS3)(dppz)Cl]Cl 1 and [Ru([12]aneS4)(dppz)]Cl2 2 ([9]aneS3 = 1,4,7- trithiaciclononane and [12]aneS4 = 1,4,7,10-tetrathiaciclododecane) were synthesised and fully characterised. These complexes belong to a small family of dipyridophenazine complexes with non-polypyridyl ancillary ligands . Interaction studies of these complexes with CT-DNA (UV/Vis titrations, steady-state emission and thermal denaturation) revealed their high affinity for DNA . Intercalation constants determined by UV/Vis titrations are of the same order of magnitude (106) as other dppz metallointercalators, namely [Ru(II)(bpy)2dppz]S2+. Differences between l and2 were identified by steady-state emission and thermal denaturation studies . Emission results are in accordance with structural data, which indicate how geometric distortions and different donor and/or acceptor ligand abilities affect luminescence. The possibility of noncovalent interactions between ancillary ligands and nucleobases by van der Waals contacts and H-bridges is discussed . Furthermore, complex l undergoes aquation under intra-cellular conditions and an equilibrium with the aquated form l' is attained . This behaviour may increase the diversity of available interaction modes

Effect of Cr(V) on reproductive organ morphology and sperm parameters: An experimental study in mice

BACKGROUND: Cr(V) species are formed during the intracellular reduction of Cr(VI), a ubiquitous environmental pollutant. In this study, the acute toxicity of a physiologically stable Cr(V) compound, [Cr(V)-BT](2- )(BT = bis(hydroxyethyl)aminotris(hydroxymethyl)methane) was investigated in the male reproductive system of sexually mature 60-day-old male ICR-CD1 mice. METHODS: Eight-week-old animals were subcutaneously injected daily with a dose of ca 8 μmol of Cr/mouse, during 5 days. The control group was injected with 0.5 mL of BT buffer. Testis and epididymis morphology was evaluated using light and transmission electron microscopy. Epididymal sperm counts, motility and acrosome integrity were also assayed using standard methods. RESULTS: Seminiferous epithelium abnormalities were detected in the Cr(V)-BT experimental group, including intraepithelial vacuolation, and remarkable degeneration of Sertoli cells, spermatocytes and spermatids. The premature release of germ cells into the tubular lumen was also evident. Histological evaluation of epididymal compartments revealed apparently normal features. However, the epididymal epithelium presented vacuolation. [Cr(V)-BT](2- )induced a reduction in sperm acrosome integrity. However, sperm motility and density were not significantly affected. CONCLUSION: This in vivo study using a Cr(V) compound, provides evidence for the potential reproductive hazards caused on male reproductive system by species containing chromium in intermediate oxidation states

The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) wide-spread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications

An easy way to Pb(Mg1/3Nb2/3)O3 synthesis

This work describes the very expeditious combustion synthesis of Pb(Mg1/3Nb2/3)O3 perovskite powders from mixtures of Pb(NO3)2, Mg(NO3)2·6H2O and Nb2O5, as cation precursors, and urea as fuel. The powders produced were characterized by XRD, SEM (EDS), and ICP and MAS NMR spectroscopies. Since, with this method, exposure to high temperatures is reduced to a minimum, the as-prepared combustion product shows no PbO loss. The % PMN in the as-prepared combustion powder is sensitive to, and increases with, the rise in the ignition temperature, and gets further improved upon calcination. However, the benefit of calcination, in terms of the reached maximum in the % PMN, becomes more modest when the ignition temperature is increased. Subsequent heat treatments of powder compacts in air (normal processing usually includes some kind of sintering step in order to improve crystallinity and densify the material), showed that over 90% Pb(Mg1/3Nb2/3)O3 can be readily obtained at 870°C.info:eu-repo/semantics/publishedVersio

Nephrotoxicity of CCA-treated wood: a comparative study with As2O5 and CrO3 on mice

The purpose of this work was to assess the acute toxicity on male mice to a chromated copper arsenate (CCA) solution, a widespread wood preservative used in building industry until 2002. Animals were subcutaneously injected with CCA (7.2 mg/kg arsenic and 10.2 mg/kg chromium per body weight), CrO3 (10.2 mg/kg), As2O5 (7.2 mg/kg) and NaCl (0.9%) per se, during 48 h and 96 h, for histopathology, histochemistry, chromium and arsenic analysis. The results showed some histopathological changes within renal tubules lumen of CCA exposed animals (during 48 h, and 96 h), and CrO3 (for the period of 96 h). Furthermore, the renal levels of arsenic and chromium in treated animals were statistically more evident than controls. Although, the same contents of pentavalent arsenic and hexavalent chromium were injected into treated animals with CCA and with the prepared solutions of As2O5 and CrO3, a different distribution of the pattern of these compounds was observed in kidneys

An easy way to Pb(Mg1/3Nb2/3)O-3 synthesis

This work describes the very expeditious combustion synthesis of Pb(Mg1/3Nb2/3)O-3 perovskite powders from mixtures of Pb(NO3)(2), Mg(NO3)(2)(.)6H(2)O and Nb2O5, as cation precursors, and urea as fuel. The powders produced were characterized by XRD, SEM (EDS), and ICP and Nb-93 MAS NMR spectroscopies. Since, with this method, exposure to high temperatures is reduced to a minimum, the as-prepared combustion product shows no PbO loss. The % PMN in the as-prepared combustion powder is sensitive to, and increases with, the rise in the ignition temperature, and gets further improved upon calcination. However, the benefit of calcination, in terms of the reached maximum in the % PMN, becomes more modest when the ignition temperature is increased. Subsequent heat treatments of powder compacts in air (normal processing usually includes some kind of sintering step in order to improve crystallinity and densify the material), showed that over 90% Pb(Mg1/3Nb2/3)O-3 can be readily obtained at 870degreesC. (C) 2002 Elsevier Science Ltd. All rights reserved.PRODEP-Portuga

Synthetic hollow zinc oxide microparticles

The preparation of hollow particles of ZnO by calcination of hydrozincite coated poly(styrene) beads is reported. Synthetic studies have been performed on such polymer/inorganic composite precursors in order to establish the optimum conditions for the preparation of the ZnO particles. The morphological properties of the powders were characterised by optical microscopy and scanning electron microscopy. The micrometric ZnO particles show morphological characteristics related to the template used in their preparation

Synthesis and structural characterization of microporous umbite, penkvilksite, and other titanosilicates

Synthetic analogues of the microporous minerals umbite (AM-2) and penkvilksite, polytype 2O (AM-3), have been prepared. The facile syntheses of two other titanosilicates, AM-1 and AM-4, have also been reported. AM-1 and the previously reported, layered titanosilicate known as JDF-L1 have been shown to have the same structure. AM-4 is a new microporous titanosilicate with a unique and unknown structure, containing eight different Na sites. All AM-n materials have been characterized by several techniques, viz. SEM, powder XRD, single- and triple-quantum 23Na and 29Si MAS NMR, water adsorption measurements, and TGA/DSC. AM-n materials are thermally stable up to ca. 600 °C. The dehydration-hydration processes seem to be reversible (or quasi reversible) for AM-1, -2, and -3 but not so for AM-4.publishe