546 resultados para DIPHENYL DISELENIDE


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Polybrominated diphenyl ethers (PBDEs) are compounds that are used as flame retardants. Human exposure is suggested to be via food, dust and air. An assessment of PBDE exposure via indoor environments using samples of air, dust and surface wipes from eight sites in South East Queensland, Australia was conducted. For indoor air, ΣPBDEs ranged from 0.5 -179 pg/m3 for homes and 15 - 487 pg/m3 for offices. In dust, ΣPBDEs ranged from 87 - 733 ng/g dust and 583 - 3070 ng/g dust in homes and offices, respectively. PBDEs were detected on 9 out of 10 surfaces sampled and ranged from non-detectable to 5985 pg/cm2. Overall, the congener profiles for air and dust were dominated by BDE-209. This study demonstrated that PBDEs are ubiquitous in the indoor environments of selected buildings in South East Queensland and suggest the need for detailed assessment of PBDE concentrations using more sites to further investigate the factors influencing PBDE exposure in Australia.

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Human half-lives of PentaBDE congeners have been estimated from the decline in serum concentrations measured over a 6-12 month period for a population of exchange students moving from North America to Australia. Australian serum PBDE concentrations are typically between 5 -10 times lower than in North America and we can therefore hypothesize that if the biological half-life is sufficiently short we would observe a decline in serum concentration with length of residence in Australia. Thirty students were recruited over a period of 3 years from whom serum were archived every 2 months during their stay in Australia. Australian residents (n=22) were also sampled longitudinally to estimate general population background levels. All serum samples were analyzed by gas chromatography high resolution mass spectrometry. Key findings confirmed that BDE-47 concentrations in the Australians (median 2.3;

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Polybrominated diphenyl ethers (PBDEs) are considered to be a cost effective and efficient way to reduce flammability therefore reducing harm caused by fires. PBDEs are incorporated into a variety of manufactured products and are found worldwide in biological and environmental samples (e.g. Hites et al. 2004). Unlike other persistent organic pollutants there is limited data on PBDE concentrations by age and/or other population specific factors. Some studies have shown no variation in adult serum PBDE concentrations with age (e.g. Mazdai et al., 2003, Meironyte Guvenius et al., 2003) while Petreas et al. (2003) and Schecter et al. (2005) found results to be suggestive of an age trend in adult data but no statistically significant correlation was found. In addition to the data on adult concentrations there is limited data which investigates the levels of PBDEs in infants and young children. Fangström et al. (2005) showed that in seven year olds there was no difference in PBDE concentration when compared to adult concentrations. While Thomsen et al. (2002, 2005) found the concentration of PBDEs in pooled samples of blood serum from a 0-4 years age group to be higher than other age groups (4 to > 60 years). In addition, a family of four was studied in the U.S. and the concentrations were found to be greatest in the 18-month-old infant followed by the 5 year old child, then the mother and father (Fischer et al., 2006). The objectives of this study were to assess age, gender and regional trends of PBDE concentrations in a representative sample of the Australian population.

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Polybrominated diphenyl ethers (PBDEs), a common class of brominated flame retardants, are a ubiquitous part of our built environment, and for many years have contributed to improved public safety by reducing the flammability of everyday goods. Recently, PBDEs have come under increased international attention because of their potential to impact upon the environment and human health. Some PBDE compounds have been nominated for possible inclusion on the Stockholm Convention on Persistent Organic Pollutants, to which Australia is a Party. Work under the Stockholm Convention has demonstrated the capacity of some PBDEs to persist and accumulate in the environment and to be carried long distances. Much is unknown about the impact of PBDEs on living organisms, however recent studies show that some PBDEs can inhibit growth in colonies of plankton and algae and depress the reproduction of zooplankton. Laboratory mice and rats have also shown liver disturbances and damage to developing nervous systems as a result of exposure to PBDEs. In 2004, the Australian Government Department of the Environment and Water Resources began three studies to examine levels of PBDEs in aquatic sediments, indoor environments and human blood, as knowledge about PBDEs in Australia was very limited. The aim of these studies was to improve this knowledge base so that governments were in a better position to consider appropriate management actions. Due to the high costs for laboratory analysis of PBDEs, the number of samples collected for each study was limited and so caution is required when interpreting the findings. Nevertheless, these studies will provide governments with an indication of how prevalent PBDEs are in the Australian population and the environment and will also contribute to international knowledge about these chemicals. The Department of the Environment and Water Resources will be working closely with othergovernment agencies, industry and the community to investigate any further action that may be required to address PBDEs in Australia.

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This study arose out of the 2002 Review of the PCB Management Plan by the Scheduled Waste Management Network (SWMN) and the National Advisory Body (NAB). The Review indicated it would be beneficial to obtain some data on the levels of organochlorine pesticides (OCPs) in the Australian population. In 2002, the Environment Protection and Heritage Standing Committee (EPHSC) agreed and noted that the Australian Government Department of the Environment and Heritage (DEH) would commission a study using the same samples from the National Dioxins Program (NDP) breast milk study collected in 2002- 03. The study, however, was also broadened to include polybrominated diphenyl ethers (PBDEs).

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PBDE concentrations are higher in children compared to adults with exposure suggested to include dust ingestion. Besides the home environment, children spend a great deal of time in school classrooms which may be a source of exposure. As part of the “Ultrafine Particles from Traffic Emissions and Children's Health (UPTECH)” project, dust samples (n=28) were obtained in 2011/12 from 10 Brisbane, Australia metropolitan schools and analysed using GC and LC–MS for polybrominated diphenyl ethers (PBDEs) -17, -28, -47, -49, -66, -85, -99, -100, -154, -183, and -209. Σ11PBDEs ranged from 11–2163 ng/g dust; with a mean and median of 600 and 469 ng/g dust, respectively. BDE-209 (range n.d. −2034 ng/g dust; mean (median) 402 (217) ng/g dust) was the dominant congener in most classrooms. Frequencies of detection were 96%, 96%, 39% and 93% for BDE-47, -99, -100 and -209, respectively. No seasonal variations were apparent and from each of the two schools where XRF measurements were carried out, only two classroom items had detectable bromine. PBDE intake for 8–11 year olds can be estimated at 0.094 ng/day BDE-47; 0.187 ng/day BDE-99 and 0.522 ng/day BDE-209 as a result of ingestion of classroom dust, based on mean PBDE concentrations. The 97.5% percentile intake is estimated to be 0.62, 1.03 and 2.14 ng/day for BDEs-47, -99 and -209, respectively. These PBDE concentrations in dust from classrooms, which are higher than in Australian homes, may explain some of the higher body burden of PBDEs in children compared to adults when taking into consideration age-dependant behaviours which increase dust ingestion.

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In the title moleclue, C25H23NO2, the 4-piperidone ring adopts a boat conformation. The molecular conformation is stabilized by an intramolecular C-H center dot center dot center dot O hydrogen bond. In the crystal, molecules are connected through weak intermolecular C-H center dot center dot center dot O hydrogen bonds.

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Syntheses and structural characterization of Ni(II) chelates of a new series of symmetric and unsymmetric tetradentate linear ligands are described. Preparative routes involve either the direct reaction between a metal complex and arene diazonium diazonium salts or a simple metal incorporation into the independently synthesized ligands. Recent X-ray structure determination of 4,9-dimethyl-5,8-diazadodeca-4,8-diene-2,11-dione-3,10-di(4′-methyl phenyl) hydrazonatonickel(II) complex reveals the geometry around the Ni(II) to be very close to square planar. The expected distortion because of the disposition of bulky aromatic groups on the neighbouring nitrogens is minimized by their projection in the opposite directions from the plane. PMP, IR and electronic spectral data for the complexes are quite in agreement with this structure.

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Proximity of molecules is a crucial factor in many solid- state photochemical processes.'S2 The biomolecular photodimerization reactions in the solid state depend on the relative geometry of reactant molecules in the crystal lattice with center-to-center distance of nearest neighbor double bonds of the order of ca. 4 A. This fact emanates from the incisive studies of Schmidt and Cohen.2 One of the two approaches to achieve this distance requirement is the so-called "Crystal-Engineering" of structures, which essentially involves the introduction of certain functional groups that display in-plane interstacking interactions (Cl...Cl, C-He-0, etc.) in the crystal The chloro group is by far the most successful in promoting the /3- packing m ~ d e ,th~o,u~gh recent studies have shown its limitations? Another approach involves the use of constrained media in which the reactants could hopefully be aligned.

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Diphenyl sulphoxide (DPSO) complexes of TiO2+, ZrO2+, VO2+ and UO22+ have been prepared and characterized by physicochemical methods. The complexes have the formulae: [TiO(DPSO)5]2 (ClO4)4, [ZrO(DPSO)6] (ClO4)2, [VO(DPSO)5](ClO4)2, [VO(DPSO)3Cl2], [UO2-(DPSO)4] (ClO4)2, [UO2(DPSO)2Cl2],[UO2(DPSO)2(NO3)2]and[UO2(DPSO)2(CH3COO)2]. The i.r. spectra show the coordination through the oxygen of the sulphoxide in all the complexes. The spectroscopic, conductivity and crysoscopic studies indicate the ionic nature of the perchlorate, while the chloride, nitrate and acetate are coordinated, the last two being bidentate. The probable stereochemistry of the complexes is discussed. The complexes decompose exothermally.

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Diphenyl sulphoxide (DPSO) complexes of some divalent metal perchlorates and chlorides are prepared The perchlorates of Mn, Co, Ni, Zn and Cd have the general formula [M(DPSO)6](CIO4)2. The Cu(II) complex is found to have the composition [Cu(DPSO)4] (CIO42. The chloro complex having the formula ZnCl2. 2DPSO, CdCl2.DPSO, HgCl2. DPSO and PdCl2. 2 DPSO have also been obtained. Infrared spectra indicate that the DPSO complexes of Mn, Co, Ni, Cu and Zn are oxygen-bonded while those of Cd, Hg and Pd are sulphur-bonded. The magnetic susceptibility and the optical spectral data reveal octahedral coordination for Mn, Co and Ni complexes. From the electronic spectra of Co and NI complexes, the ligand field parameters, Dq and β, are calculated.

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Thorium(IV) is known to form high coordination-number complexes. An attempt has therefore been made to determine the effect of anions on the coordination complexes of diphenyl sulphoxide (DPSO) with thorium(IV). The complexes formed have the formulae [Th(DPSO)6](ClO4)4, [Th(DPSO)4Cl4], [Th(DPSO)4Br4], [Th(DPSO)6I2]I2, [Th(DPSO)4(NCS)4]and [Th(DPSO)3(NO3)4]. In all the complexes, DPSO is coordinated to the metal ion through its oxygen. The electrical conductances in nitrobenzene and in nitromethane, and ebullioscopic molecular weights in acetonitrile, show that the perchlorate and iodide complexes behave as 1:4 and 1:2 electrolytes, respectively; while the other complexes are monomeric and non-electrolytes. The infrared spectra of the solid complexes indicate the ionic nature of the perchlorate, the bidentate nature of the nitrate and the coordination of the thiocyanate through its nitrogen. [Th(DPSO)4Cl4], [Th(DPSO)4Br4]and [Th-(DPSO)3 (NO3)4]decompose endothermically while [Th(DPSO)6](ClO4)4 and [Th(DPSO)4(NCS)4]decompose exothermically, both in air and in nitrogen. The perchlorate complex has octahedral symmetry around the thorium, the halo- and the thiocyanato complexes are 8-coordinate, probably with square antiprismatic structures, while the nitrate complex is 11-coordinate

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Reactions of cis-[(C6H5N)PC1]z(1 ) with the difunctional reagents HO(CH2)20H,H (CH3)N(CHz)zN(CH3)HH, (CH3)N(CH& OH, and HO(CHz)30Hi n the presence of triethylamine yield the new bicyclic 1,3,2X3,4h3-diazadiphosphetidines[( C6H5- N)PIZ[-O(CHZ)Zo-l (2), [(C6H5N)PlZ[-(CH3)N(CHZ)ZN(CH3)-l (319 [(C6H~N)PlZ~-(CH3)N(cHZ)20 (4), and [(C6H5 N)P],[-Q(CH2),0-] (5), respectively. The products have been characterized by elemental analyses and IR and NMR spectroscopic data. The structures of 4 and 5 have been determined by single-crystal X-ray analysis. Crystal data for 4: monoclinic, P2,/c, a = 9.823 (2) A, b = 8.608 (1) A, c = 18.423 (3) A, i3 = 90.55 (1)O, Z = 4. Crystal data for 5 monoclinic, P2,/c, a = 9.727 (2) A, b = 8.064 (2) A, c = 19.702 (4) A, @ =I 91.31 (l)', 2 = 4. The structures have been solved by direct methods and refined to R = 0.028 for 4 and R = 0.050 for 5. Compound 4 is the first example of an aminoalkoxy-l,3,2X3,4X3-diazadiphosphetidine. The PzNz ring is slightly puckered in both 4 and 5 and the puckering occurs in a manner opposite to that observed for cis-[(RN)PX],structures.