Abstract  There is concern that offshore oil platforms off Southern California may be contributing to environmental contaminants accumulated by marine fishes. To examine this possibility, 18 kelp bass (Paralabrax clathratus Girard, 1854), 80 kelp rockfish (Sebastes atrovirens Jordan and Gilbert, 1880), and 98 Pacific sanddab (Citharichthys sordidus Girard, 1854) were collected from five offshore oil platforms and 10 natural areas during 2005-2006 for whole-body analysis of 63 elements. Forty-two elements were excluded from statistical comparisons as they (1) consisted of major cations that were unlikely to accumulate to potentially toxic concentrations; (2) were not detected by the analytical procedures; or (3) were detected at concentrations too low to yield reliable quantitative measurements. The remaining 21 elements consisted of aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, gallium, iron, lead, lithium, manganese, mercury, nickel, rubidium, selenium, strontium, tin, titanium, vanadium, and zinc. Statistical comparisons of these elements indicated that none consistently exhibited higher concentrations at oil platforms than at natural areas. However, the concentrations of copper, selenium, titanium, and vanadium in Pacific sanddab were unusual because small individuals exhibited either no differences between oil platforms and natural areas or significantly lower concentrations at oil platforms than at natural areas, whereas large individuals exhibited significantly higher concentrations at oil platforms than at natural areas.

Abstract  A series of five vanadia on alumina catalysts for oxidative dehydrogenation of propane to propene were synthesized by flame spray pyrolysis (FSP) using vanadium(III)acetylacetonate and aluminium(III)acetylacetonate dissolved in toluene as precursors. The vanadium loading was 2, 3, 5, 7.5 and 10 wt.%. The catalysts were subsequently characterized by BET surface area, X-ray diffraction (XRD), Raman, UV-vis diffuse reflectance and X-ray absorption spectroscopy (XAS) as well as measurement of the catalytic performance. The catalysts had specific surface areas from 143 to 169 m(2)/g corresponding to average particles diameters from 9.0 to 10.9 nm and apparent vanadia surface densities from 1.4 to 8.4 VOx/nm(2). The only crystalline phase detected by XRD was gamma-Al2O3, except at 10 wt.% vanadium where traces of crystalline vanadia were observed. Raman spectroscopy showed vanadia monomers at 2 and 3 wt.% V (1.4 and 2.1 VOx/nm(2)), a mixture of vanadia oligomers and monomers at 5 wt.% V (3.6 VOx/nm(2)) and mainly oligomers at 7.5 and 10 wt.% V (6.0 and 8.4 VOx/nm(2)). Diffuse reflectance UV vis and extended X-ray absorption fine structure (EXAFS) spectroscopy measurements supported the results of Raman spectroscopy. In situ X-ray absorption near edge structure (XANES) spectroscopy showed that the vanadia can be reduced when operating at low oxygen concentrations. The catalyst performance was determined in fixed bed reactors with an inlet gas composition of C3H8/O-2/N-2 = 5/25/70. The main products were propene, CO and CO2, with traces of ethene and acrolein. Comparing propene selectivity as function of propane conversion the most selective catalysts were the 2 and 3 wt.% V samples, which contained mostly vanadia monomers according to Raman spectroscopy. The best propene yield of 12% was obtained with the 2 wt.% vanadium catalyst while the best space time yield of 0.78 g(propene)/(g(cat).h) at 488 degrees C was obtained with the 3 wt.% V catalyst. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Density functional theory (DFT) and coupled cluster theory (CCSD(T)) calculations are carried out to investigate the electronic and structural properties of a series of bimetallic oxide clusters MW2O9(-/0) (M=V, Nb, Ta). Generalized Koopmans' theorem is applied to predict the vertical detachment energies (VDEs) and simulate the photoelectron spectra (PES). Theoretical calculations at the B3LYP level yield singlet and doublet ground states for the bimetallic anionic and neutral clusters, respectively. All the clusters present the six-membered ring structures with different symmetries, except that the TaW2O9(-) cluster shows a chained style with a penta-coordinated tantalum atom. Spin density analyses reveal oxygen radical species in all neutral clusters, consistent with their structural characteristics. Moreover, additional calculations are performed to study the oxidation reaction of CO molecule with the W3O9(+) cation and the isoelectronic VW2O9 cluster, and results indicate that the introduction of vanadium at tungsten site can efficiently improve the oxidation reactivity.

Abstract  The driving mechanism of the metal-insulator transition (MIT) in VO(2) has always attracted attention, in particular with regards to understanding if and how the doping mechanism may tune the MIT transition temperature. However, due to the lack of detailed local structural information, in this oxide the underlying MIT mechanism is still matter of debate. In this contribution on the V(1-x)W(x)O(2) system, we attempt to clarify the origin of the MIT induced by tungsten doping. Combining W L(3)-edge and V K-edge extended X-ray absorption fine-structure (EXAFS) spectroscopy, the local structures around both V and W have been obtained. The data point out the occurrence of internal stress along the V-V chains induced by doping. It reaches a critical value that remains constant during the transition. The main effect of the internal stress on the vanadium local structure has also been identified. Actually, upon increasing the dopant concentration, the tilt of the V-V pairs towards the apex oxygen atoms in the VO(6) octahedron decreases while the V-V bond lengths remain unchanged. The electronic structure has also been investigated by O K-edge X-ray absorption near-edge structure (XANES) spectroscopy. Actually, at high doping concentrations the interaction of O(2p) and the V d(∥) state increases, while the hybridization of O(2p) and V π* decreases. The O(2p)-V(3d) hybridization is therefore an essential parameter correlated with the decreasing transition temperature in the V(1-x)W(x)O(2) system.

Abstract  Doping VO(2) with tungsten can lower the metal-insulator transition (MIT) temperature and thus provide a controlled means for tailoring the MIT properties of VO(2) materials. Here, infrared spectroscopy has been employed as a tool for identifying structural changes in doped VO(2) as a way of lowering the MIT temperature.

Abstract  Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive DC and pulsed-DC magnetron sputtering. The influence of substitutional doping of V by higher valence cations, such as W, Mo, and Nb, and respective contents on the crystal structure of VO2 is evaluated. Moreover, the effectiveness of each dopant element on the reduction of the intrinsic transition temperature and infrared modulation efficiency of VO2 is discussed. In summary, all the dopant elements--regardless of the concentration, within the studied range-- formed a solid solution with VO2, which was the only compound observed by X-ray diffractometry. Nb showed a clear detrimental effect on the crystal structure of VO2. The undoped films presented a marked thermochromic behavior, specially the one prepared by pulsed-DC sputtering. The dopants effectively decreased the transition of VO2 to the proximity of room temperature. However, the IR modulation efficiency is markedly affected as a consequence of the increased metallic character of the semiconducting phase. Tungsten proved to be the most effective element on the reduction of the semiconducting-metal transition temperature, while Mo and Nb showed similar results with the latter being detrimental to the thermochromism.

Abstract  Kinetic and isotopic tracer and exchange measurements were used to determine the identity and reversibility of elementary steps involved in ethane oxidative dehydrogenation (ODH) on VOx/Al2O3 and VOx/ZrO2. C2H6-C2D6-O2 and C2H6-D2O-O2 react to form alkenes and COx without concurrent formation of C2H6-xDx or C2H4-xDx isotopomers, suggesting that C-H bond cleavage in ethane and ethene is an irreversible and kinetically relevant step in ODH and combustion reactions. Primary ethane ODH reactions show normal kinetic isotopic effects (kC-H/kC-D ) 2.4); similar values were measured for ethane and ethene combustion (1.9 and 2.8, respectively). 16O2-18O2-C2H6 reactions on supported V16Ox domains led to the initial appearance of 16O from the lattice in H2O, CO, and CO2, consistent with the involvement of lattice oxygen in C-H bond activation steps. Isotopic contents are similar in H2O, CO, and CO2, suggesting that ODH and combustion reactions use similar lattice oxygen sites. No 16O18O isotopomers were detected during reactions of 16O2- 18O2-C2H6 mixtures, as expected if dissociative O2 chemisorption steps were irreversible. The alkyl species formed in these steps desorb irreversibly as ethene and the resulting O-H groups recombine to form H2O and reduced V centers in reversible desorption steps. These reduced V centers reoxidize by irreversible dissociative chemisorption of O2. A pseudo-steady state analysis of these elementary steps together with these reversibility assumptions led to a rate expression that accurately describes the observed inhibition of ODH rates by water and the measured kinetic dependence of ODH rates on C2H6 and O2 pressures. This kinetic analysis suggests that surface oxygen, OH groups, and oxygen vacancies are the most abundant reactive intermediates during ethane ODH on active VOx domains.

Abstract  The redox properties of V-O layers supported on TiO2, A12O3, and SiO2 have been examined and discussed in terms of structural models. On this basis monodispersed VO4 units are postulated on the (001) plane of anatase (TiO2), located at the cationic sites with two terminal and two bridging oxygens, one of the latter being removed on reduction. Dimeric, pyrovanadate-type species seem to be predominantly formed on γ-Al2O3, whereas grains of poorly crystalline V2O5 are observed on SiO2. The structure of the vanadium-oxygen species determines the number of oxygens which can be removed per V atom.

Abstract  New complexes of dioxovanadium(V), zinc(II), ruthenium(II), palladium(II), and platinum(II) with 6-methylpyridine-2-carbaldehyde-N(4)-ethylthiosemicarbazone (HmpETSC) have been synthesized. The composition of these complexes is discussed on the basis of elemental analyses, IR, Raman, NMR ((1)H, (13)C, and (31)P), and electronic spectral data. The X-ray crystal structures of [VO(2)(mpETSC)] and [Pt(mpETSC)Cl] are also reported. The HmpETSC and its [Zn(HmpETSC)Cl(2)] and [Pd(mpETSC)Cl] complexes exhibit antineoplastic activity against colon cancer human cell lines (HCT 116).

Abstract  The polyoxomolybdates encapsulated PAni hybrid materials are prepared by interfacial polymerisation. In P12MPA, the crystal structure of 12MPA is not modified on doping with PAni, However, P11MPA have the polycrystallinity due to the presence of vanadium in the dopant molecule. Though, the hybrids prepared by interfacial polymerisation are in emaraldine salt form, there is a blue shift in the absorption spectra due to dopant induced decrease in conjugation length and over-oxidation. Interfacially polymerised PAniPOM hybrid materials are exposed with various concentrations of vapours of different volatile organic compounds (VOC) Such as acetone, methanol, chloroform and carbon tetrachloride. The oxidising VOCs like acetone and methanol on exposure to PAni decrease the resistivity by hydrogen bonding with the redox cites of the polymer. Among these two, the sensitivity towards acetone is more in PAni and its hybrids which can be linked with the vapour pressure of the analyte. Due to the weak acidic characteristics of chlorinated hydrocarbons which are reducing vapours, the resistivity of PAni and its hybrids increases on exposure to chloroform and CCl4. Here, the chlorinated hydrocarbons interact with the redox sites of PAni and reduce it to base form. Bridging of polymer chains is also proposed for the reduction of conductivity oil exposure to the analyte. The sensitivity is higher for the reducing analytes than that of the oxidising one. (C) 2009 Elsevier B.V. All rights reserved

Abstract  Extraction of vanadium(IV) from sulphate acid solution was studied using organophosphorous-based extractants D2EHPA, EHEHPA and CYANEX 272 in kerosene. The different parameters affecting the extraction of vanadium(IV) under equilibrium conditions were separately investigated to elucidate the stoichiometry of the extracted species. The distribution ratio of vanadium increased with increasing equilibrium pH of the aqueous phase, concentration of the extractants and temperature. D2EHPA was found to be a stronger extractant, having greater pH functionality than EHEHPA and CYANEX 272. Extraction of vanadium(IV) by these organophosphorous-based extractants involved cation exchange mechanism, and the extracted species appear to be VOR2(HR)(2) in the low equilibrium pH and VOR2 in the higher equilibrium pH, where HR refers to the three acidic extractants.

Abstract  Bending characteristics were studied in rods used for spinal instrumentation at in-situ contouring conditions. Five groups of five 6 mm diameter rods made from: cobalt alloy (VITALLIUM), titanium-aluminum-vanadium alloy (SDI (TM)), beta-titanium alloy (TNTZ), cold worked stainless steel (STIFF), and annealed stainless steel (MALLEABLE) were studied. The bending procedure was similar to that typically applied for in-situ contouring in the operating room and included two bending cycles: first-bending to 21-24 degrees under load with further release of loading for 10 min, and second-bending to 34-37 degrees at the previously bent site and release of load for 10 min. Applied load, bending stiffness, and springback effect were studied. Statistical evaluation included ANOVA, correlation and regression analysis. TNTZ and SDI (TM) rods showed the highest (p < 0.05) springback at both bending cycles. VITALLIUM and STIFF rods showed mild springback (p < 0.05). The least (p < 0.05) springback was observed in the MALLEABLE rods. Springback significantly correlated with the bend angle under load (p < 0.001). To reach the necessary bend angle after unloading, over bending should be 37-40% of the required angle in TNTZ and SDI (TM) rods, 27-30% in VITALLIUM and STIFF rods, and around 20% in MALLEABLE rods. (c) 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 98B: 192-200, 2011.

Abstract  Different catalysts vanadium-based supported on mixed oxide (CeO2, TiO2, CuFe2O4) were prepared, characterized and tested for the partial selective oxidation of H2S at low temperature. These catalysts were compared in terms of H2S and O-2 conversion, SO2 selectivity and durability in the range of temperature 50-250 degrees C. Results proved that the most interesting catalysts were V2O5/CeO2 and V2O5/CuFe2O4 that showed very high H2S and O-2 conversion (>95%) and respectively a SO2 selectivity of 14% and 20%. Based on the promising results, a deeper study on the V2O5/CeO2 catalyst was performed by investigating the influence of H2S concentrations, space velocity, and the O-2/H2S molar feed ratio to order to minimize the SO2 selectivity. Furthermore, on this sample it was performed a kinetic preliminary study to evaluate the kinetics data to the correct design of a catalytic reactor for the biogas clean-up to feed MCFC. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Abstract  A novel columnar activated carbon was prepared from agricultural waste walnut shell and applied for flue gas desulfurization. The pyrolusite was blended with the walnut shell chars as a catalyst in the process of CO2 activation. The produced activated carbons were characterized using Brunauer-Emmett-Teller (BET), Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), in order to evaluate the effects of pyrolusite addition on the properties of activated carbon. The BET results indicated that the activated carbon with 5 wt.% pyrolusite addition had the highest BET value of 687 m(2)/g and total pore volume of 0.45 cm(3)/g, which were 21.6% and 18.4%, respectively, higher than the blank sample. The XRD and XPS results showed that the manganese oxide in pyrolusite was evenly dispersed in the activated carbon's matrix. Compared to the blank activated carbon (137 mg/g), the pyrolusite-modified activated carbon with 5 wt.% pyrolusite achieved 243 mg/g of sulfur adsorption capacity. This could be attributed to the improvement of carbon porous structures during the activation of pyrolusite-modified activated carbon and to the catalytic oxidation of SO2 in desulfurization process.

Abstract  Vanadium, a dietary micronutrient, is now proving to be a promising anti-tumour agent. The present study was conducted to ascertain its anti-neoplastic potential against an experimental mammary carcinogenesis. Female Sprague-Dawley rats at 50 days of age were treated with 7,12-dimethylbenz(alpha)anthracene (DMBA; 0.5 mg per 100 g body weight) by a single tail vein injection in an oil emulsion. Vanadium (ammonium monovanadate) at a concentration of 0.5 p.p.m. was supplemented in the drinking water and given ad libitum to the experimental group immediately after the carcinogen treatment and it continued until the termination of the study (24 weeks for histological, immunological and biochemical observations and 35 weeks for morphological findings). It was found that vanadium treatment brought about substantial protection against DMBA-induced mammary carcinogenesis. This was evident from histological findings that showed substantial repair of hyperplastic lesions following supplementation of vanadium alone. There was a significant reduction in incidence (P < 0.05), total number, multiplicity (P < 0.01), size of palpable mammary tumours and delay in mean latency period of tumour appearance (P < 0.001) following vanadium supplementation compared to the DMBA control. The immunohistochemical localization of metallothionein (a prognostic marker for breast cancer) showed reduced expression with vanadium treatment. Further, DNA fragmentation in the mammary tissue of the vanadium-treated group indicated apoptosis. In this group, vanadium also caused a significant decrease in the number (P < 0.002) and focal area (P < 0.05) of gamma-glutaminetranspeptidase-positive hepatic foci. The results clearly show the anti-neoplastic potential of vanadium.

Abstract  Limited information is available on the trace element contents of soils and crops in Saskatchewan. Trace elements, to a large extent, are derived from soil parent materials and partially from anthropogenic activities, such as agricultural application of fertilizers. The objective of this study was to establish levels of trace element concentrations of the surface horizons and parent materials of selected soils, fertilizers, and durum wheat (Triticum durum Desf.). Inductively coupled plasma mass spectrometry (ICP-MS) having the capacity to determine 60 elements simultaneously at very low detection levels was used. Trace elements for this work are among the most frequently reported in the recent literature. We found a positive relationship between the total contents of trace elements and percent of clays in the soils, except Se. This suggests that the major part of the elements studied are associated with the clay minerals in soils. In two Regina heavy clay soils, total Cu, Zn, Se, and Pb were higher in the surface soil than the subsoil, but this increase was statistically not significant. All the elements, except Zn, Cd, and Pb, were depleted in soils that have lower clay content in the surface horizon than the parent material. Soils having similar clay contents in the surface horizon and subsoil, total V, Cr, Co, Ni, Zn, Cd, Sn, Sb, Tl, and Pb concentrations were higher in the surface horizon, relative to parent material. Only Zn and Cd increases were significant. Enrichment of elements in the surface horizons was, in part, attributed to anthropogenic additions. Experiments with EDTA and DTPA extraction techniques showed that almost half of Co, As and Cd, and other elements in fertilizers were between 4 and 50% in somewhat available form for plants indicating their potential for soil pollution.

Abstract  The sol gel method is used for the preparation of undoped and manganese-doped Zn2SiO4 particles embedded in SiO2 host matrix with supercritical drying of ethyl alcohol in two steps. Zn2SiO4 and Zn2SiO4: Mn were prepared by simple solid-phase reaction in a natural atmosphere at 1200 degrees C after the incorporation of the nanoparticles of ZnO and ZnO: Mn, respectively, in the silica monolith. The photoluminescence (PL) measurements show a band centered at about 760 nm in the case of non-doped Zn2SiO4 which is attributed to energy transfer from Zn2SiO4 particles to NBOHs interface defects. In the case of Manganese doped Zn2SiO4, the PL reveals a band centered at about 525 nm attributed to Mn2+ in Zn2SiO4. Photoluminescence excitation (PLE) measurements show different origins of the emission. It was suggested that electronic transition T-4(1)((4)G)->(6)A(1)(S-6) associated with Mn2+ ions in willemite and the presence of Mn2+ in intensive crystal field were responsible for these luminescence band centered at 525 nm. (C) 2013 Elsevier B.V. All rights reserved.

Abstract  In the present study, the authors evaluated the anticancer mechanism of vanadium, a dietary micronutrient and an important pharmacological agent, on a defined model of chemically induced rat mammary carcinogenesis in vivo and on human breast cancer cell line MCF7 in vitro. Female Sprague-Dawley rats were treated with 7,12-dimethylbenz(alpha)anthracene (0.5 mg/100 g body weight) by a single tail vein injection in an oil emulsion to induce mammary preneoplasia. Vanadium (ammonium monovanadate) at a concentration of 0.5 ppm (4.27 mu mol/l) was supplemented in drinking water and given ad libitum to the experimental groups for 24 weeks. Histological finding showed substantial repair of hyperplastic lesions. There was a significant reduction in incidence, multiplicity (34%, p < 0.01), size of palpable mammary tumors and delay in mean latency period of tumor appearance. Immunohistochemical analysis in vivo indicated a decrease in cell proliferation (24.68% p < 0.05) and an increase among the TUNEL-positive apoptotic cells along with strong expressions of p53 and Bax, and downregulation of Bcl2 proteins in the mammary tissue of vanadium-treated animals. Further, MCF7 cells were cultured in minimal essential medium and were treated with 100, 175 and 250 mu M of vanadium (ammonium monovanadate) for 36 hr. Exposure of MCF7 cells to vanadium led to induction of apoptosis in a dose-dependent manner. It was found further that vanadium treatment brought about a prominent cell cycle arrest and chromosomal condensation, leading to apoptosis (42.62 %, p < 0.05). Results of both the in vivo and in vitro study demonstrate that vanadium has the potential to be developed into an anti-breast cancer drug in the near future. (c) 2006 Wiley-Liss, Inc.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Trace metals in sediment cores from the Gulf of Mexico, in the Campeche shelf area were studied to investigate possible variations in their vertical and/or horizontal sedimentary distributions. Possible links to petroleum sources were investigated as this area contains very productive oil exploration and transportation activities. Sediments were collected undisturbed using a vegematic type box corer. The upper 10 cm. were collected and cut in sections of 2 cm each. Incomplete, open vessel sediment digestion and atomic absorption was used for trace element determination. Particular interest was placed on vanadium and nickel concentrations as they have been associated to oil. Several metals were measured and representative distributions are presented. Horizontal distributions appear to conform to predominant current circulation patterns reported and closeness to sources of sedimentary materials. Vertical distributions are discussed. The vertical distributions were strikin

Abstract  To evaluate representative elemental composition of agricultural soils in japan and to investigate the relationship between elemental composition of agricultural soils and their soil type, land use and region in Japan, 180 soil samples were collected from the surface layer of paddy or upland fields in Japan and their total contents of 20 elements were determined. Total concentrations of aluminum (Al), iron (Fe), calcium (Ca), magnesium (Mg), titanium (Ti), phosphorus (P), manganese (Mn), barium (Ba), vanadium (V), strontium (Sr), zinc (Zn), copper (Cu) and nickel (Ni) were determined by ICP-AES and those of potassium (K) and sodium (Na) by atomic absorption spectrophotometry after wet digestion of the finely ground samples with nitric acid (HNO3), hydrofluoric acid (HF) and perchloric acid (HClO4). Total concentration of selenium (Se) was determined by HPLC after treatment of the wet digested solution (HNO3 and HClO4) of the samples with 2,3-diaminonaphthalene and extraction with cyclohexane. Total concentrations of carbon (C) and nitrogen (N) were determined by the dry combustion method, and those of silicon (Si) and oxygen (0) were determined by calculation. The medians of the total concentrations of the 10 major elements were 504 g O kg(-1), 291 g Si kg(-1), 76.6g Al kg(-1), 36.8 g Fe kg(-1), 24.8 g C kg(-1), 15.0 g K kg(-1), 14.3 g Na kg(-1), 11.9 g Ca kg(-1), 8.78 g Mg kg(-1) and 3.82 g Ti kg(-1), which accounted for 98.7% of the total. The medians of the others were 2.15 g N kg(-1), 1.43 g P kg(-1), 705 mg Mn kg(-1), 394 mg Ba kg(-1), :140 mg V kg(-1), 125 mg Sr kg(-1), 90.5 mg Zn kg(-1), 24.5 mg Cu kg(-1), 14.3 mg Ni kg(-1) and 0.42 mg Se kg(-1). In terms of soil type, volcanic soils had relatively high Al, Fe, C, N and P contents and alluvial soils had relatively high Si, K and Ba contents, whereas red yellow soils had extremely low Ca, Mg and Na contents. In terms of land use, upland soils had significantly higher Al, Fe, C, Ca, Mg, Ti, N, P, Mn, V and Se contents and lower Si, K and Ba contents than paddy soils. Cluster analysis of elemental composition of agricultural soils grouped regions in Japan into three groups: (1) Okinawa region, (2) Hokkaido, Tohoku, Kanto, Chugoku and Kyushu regions, and 3) Hokuriku-Chubu, Kinki and Shikoku regions, reflecting their soil types. In conclusion, these data can be used as basic information on which development of sustainable agriculture and promotion of environmental conservation is to be established.

Abstract  Ten kinds of dominant plants in Vanadium/Titanium mine area were collected, the contents of heavy metals including Pb, Zn, Cu, Cr, Cd and Ti of which aboveground and underground parts were determined by ICP-AES using microwave digestion, respectively. All samples of the plants were digested with HNO3-H2O2 system. The relative standard deviation was less than 5% for all the elements, and the recoveries were 92.90%similar to 103.85% by adding standard recovery experiment. This method was simple, sensitive and precise and can perform simultaneous multi-elements determination compared with conventional method of the plants determination, which could satisfy the sample examination request and provide scientific rationale for determining inorganic elements of plants.

Abstract  To improve N-2 selectivity and lower the cost, WO3 in V2O5/WO3-TiO2 was substituted by a low cost composition Fe2O3 for selective catalytic reduction (SCR) of NO with NH3. The SCR reaction over V2O5/Fe2O3-TiO2 mainly followed the Eley-Rideal mechanism (i.e. the reaction between activated ammonia species and gaseous NO). There were two active components on V2O5/WO3-TiO2 for the activation of adsorbed NH3 (i.e. V5+ and Fe3+). The acid sites on V2O5/Fe2O3-TiO2 mainly resulted from the support Fe2O3-TiO2, so the adsorbed NH3 preferred to be activated by Fe3+ rather than by V5+. V5+ on V2O5/Fe2O3-TiO2 could accelerate the regeneration of Fe3+ on Fe2O3-TiO2 due to the rapid electron transfer between V5+ and Fe2+ on the surface, so the activation of adsorbed NH3 by Fe3+ was promoted. As some NH3 adsorbed on V2O5/Fe2O3-TiO2 was not activated by Fe3+, the inactivated NH3 could then be activated by V5+ on the surface. As a result, 2% V2O5/Fe2O3-TiO2 showed excellent SCR activity, N-2 selectivity and H2O/SO2 durability at 300-450 degrees C. Furthermore, the emission of 2% V2O5/Fe2O3-TiO2 to the fly ash can be prevented by an external magnetic field due to its inherent magnetization. Therefore, 2% V2O5/Fe2O3-TiO2 could be a promising low-cost catalyst in NO emission control.

Abstract  BACKGROUND: Exposure to metal-containing particulate matter has been associated with adverse pulmonary responses. Metals in particulate matter are soluble, hence are readily recovered in urine of exposed individuals. This study investigated the association between urinary metal concentrations and the fractional concentration of expired nitric oxide (F(E)NO) in boilermakers (N = 32) exposed to residual oil fly ash (ROFA).

METHODS: Subjects were monitored at a boiler overhaul site located in the New England area, USA. F(E)NO and urine samples were collected pre- and post-workshift for 5 consecutive workdays. Metals investigated included vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), and lead (Pb).

RESULTS: The median F(E)NO was 7.5 ppb (95% CI: 7.4-8.0), and the median creatinine-adjusted urinary metal concentrations (mug/g creatinine) were: vanadium, 1.37; chromium, 0.48; manganese, 0.30; nickel, 1.52; copper, 3.70; and lead, 2.32. Linear mixed-effects models indicated significant inverse exposure-response relationships between log F(E)NO and the log-transformed urinary concentrations of vanadium, manganese, nickel, copper, and lead at several lag times, after adjusting for smoking status.

CONCLUSIONS: Urine samples may be utilized as a biomarker of occupational metal exposure. The inverse association between F(E)NO and urinary metal concentrations suggests that exposure to metals in particulate matter may have an adverse effect on respiratory health.

Abstract  Transparent conducting oxide thin films are used as front contact material for dye-sensitized solar cells This study investigated the effects of chromium (Cr) and vanadium (V) contents on the chemical and heat stability properties of aluminum-doped zinc oxide (AZO) thin films using pulsed direct current magnetic sputtering on Corning 1737F glass substrates. The experimental results show that Cr and V doping is useful for improving the chemical and thermal stability of AZO films The energy gap for AZO thin films is between 3.65 and 3.69 eV. The resistivity of the AZO.Cr V thin film was 4.23 x 10(-4) Omega cm at a Cr/V ratio of 0 30/0.23 wt %, deposition power of 150 W. working distance of 5.5 cm, substrate temperature of 473 K, working pressure of 0 4 Pa, and frequency of 10 kHz. This value is lesser than (and therefore superior to) the resistivity of SnO(2):F (FTO) films (6.5 x 10(-4) Omega cm), but greater than that of SnO(2):In (ITO) thin films (1.2 x 10(-4) Omega cm). The resistivity increased by about 0 27% after electrolyte etching, which is similar to the 0.16% increase observed for the ITO thin film. After a thermal cycle test at 673 K. the resistivity of the AZO.Cr.V film increased to 5.42 x 10(-4) Omega cm, which is better than the resistivity of the ITO and FTO films after the same thermal cycle (C) 2010 Elsevier B V All rights reserved

Abstract  A series of V-Mg-O catalysts with different loadings of vanadia were prepared by the wet impregnation method and the effect of the local structure of these catalysts on the oxidative dehydrogenation of ethylbenzene with N(2)O was investigated. High styrene selectivity (similar to 97%) was obtained at 773 K. The characterization of catalysts with methods such as XRD, FTIR, UV-visible, TPR, NMR and Laser Raman spectroscopy suggested that magnesium orthovanadate is the predominant vanadium containing phase and the size of the orthovanadate domains increases with increasing vanadia loading. The rate of ODH of ethylbenzene per V atom increases with vanadia loading and reaches a maximum at 10 wt%. The specific activity, i.e. the conversion of ethylbenzene per unit surface area of the catalysts, also exhibited a maximum at a vanadia loading of 10 wt% leading to the conclusion that activity of these catalysts is due to the presence of very small domains of Mg(3)(VO(4))(2) on the surface of MgO rather than crystallites of bulk Mg(3)(VO(4))(2). The higher styrene yield in the presence of N(2)O can be ascribed to the ability of N(2)O to keep vanadium species at a higher oxidation state.