Abstract  The oxovanadium(IV) complexes [VO(acac)(2)(Hpz)].HC(pz)(3) 1.HC(pz)(3) (acac= acetylacetonate, Hpz = pyrazole, pz = pyrazoly1) and [VOCl2{HOCH2C(pz)(3)}] 2 were obtained from reaction of [VO(acac)(2)] with hydrotris(1-pyrazolyl)methane or of VCl(3)with 2,2,2-tris(1-pyrazolyl)ethanol. The compounds were characterized by elemental analysis, IR, Far- IR and EPR spectroscopies, FAB or ESI mass-spectrometry and, for 1, by single crystal X-ray diffraction analysis. 1 and 2 exhibit catalytic activity for the oxidation of cyclohexane to the cyclohexanol and cyclohexanone mixture in homogeneous system (TONS up to 1100) under mild conditions (NCMe, 24h, room temperature) using benzoyl peroxide (BPO), tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid (mCPBA), hydrogen peroxide or the urea-hydrogen peroxide adduct (UHP) as oxidants. 1 and 2 were also immobilized on a polydimethylsiloxane membrane (1- PDMS or 2-PDMS) and the systems acted as supported catalysts for the cyclohexane oxidation using the above oxidants (TONs up to 620). The best results were obtained with mCPBA or BP0 as oxidant. The effects of various parameters, such as the amount of catalyst, nitric acid, reaction time, type of oxidant and oxidant-to-catalyst molar ratio, were investigated, for both homogeneous and supported systems. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Highly active TiO2/V-TiO2 composite photocatalysts with an n-n heterojunction semiconductor structure have been prepared by mixing TiO2 sol with sol-gel derived V-TiO2 powders that have adsorbed ammonium oleate in advance, followed by drying and calcination. These composite photocatalysts were characterized by XRD, TEM, BET, XPS, UV-vis and PL spectroscopy. The photodegradation of methyl orange in aqueous solution under UV-vis light irradiation has been investigated over TiO2-based photocatalysts consisting of different TiO2/V- TiO2 ratios and different vanadium contents. TiO2/V-TiO2 composite photocatalysts were generally shown to have a much higher photocatalytic destruction rate than that of undoped TiO2, which is ascribed mainly to the electrostatic-field-driven electron-hole separation in TiO2/V-TiO2 composite photocatalysts. The best TiO2/V-TiO2 composite with the mass ratio of TiO2:0.5 at.%V- TiO2 equal to 12:1 demonstrates 5.9 times the photocatalytic activity of that of undoped TiO2 with comparable crystallite size and specific surface area. The effect of photocatalysts composition on the photoactivity was discussed. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  Visible-light-sensitive vanadium-doped TiO2 hollow microspheres were prepared by a novel one-step template method. The novel catalysts showed pure anatase phase and better spherical morphology, compared with that of the traditional samples. The possible formation mechanism of TiO2 hollow microspheres prepared by the novel method has been proposed. The samples fabricated by the novel method not only exhibited the superior photocatalytic activity for the decomposition of methylene blue under visible-light irradiation, but also can be readily recovered from the solution by filtration after the photocatalysis. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  Hydrogenolysis reactions of so-called lignin model dimers using a Ru-xantphos catalyst are presented (xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene). For example, of some nine models studied, the alcohol, 2-(2-methoxyphenoxy)-1-phenylethanol (1), with 5 mol% Ru(H)(2)(CO)(PPh(3))(xantphos) (18) in toluene-d(8) at 135 °C for 20 h under N(2), gives in ~95% yield the C-O cleavage hydrogenolysis products, acetophenone (14) and guaiacol (17), and a small amount (<5%) of the ketone, 2-(2-methoxyphenoxy)-1-phenylethanone (4), as observed by (1)H NMR spectroscopy. The in situ Ru(H)(2)(CO)(PPh(3))(3)/xantphos system gives similar findings, confirming a recent report (J. M. Nichols et al., J. Am. Chem. Soc., 2010, 132, 12554). The active catalyst is formulated 'for convenience' as 'Ru(CO)(xantphos)'. The hydrogenolysis mechanism proceeds by initial dehydrogenation to give the ketone 4, which then undergoes hydrogenolysis of the C-O bond to give 14 and 17. Hydrogenolysis of 4 to 14 and 17 also occurs using the Ru catalyst under 1 atm H(2); in contrast, use of 3-hydroxy-2-(2-methoxyphenoxy)-1-phenyl-1-propanone (7), for example, where the CH(2) of 4 has been changed to CHCH(2)OH, gives a low yield (≤15%) of hydrogenolysis products. Similarly, the diol substrate, 2-(2-methoxyphenoxy)-1-phenyl-1,3-propanediol (9), gives low yields of hydrogenolysis products. These low yields are due to formation of the catalytically inactive complexes Ru(CO)(xantphos)[C(O)C(OC(6)H(4)OMe)=C(Ph)O] (20) and/or Ru(CO)(xantphos)[C(O)CH=C(Ph)O] (21), where the organic fragments result from dehydrogenation of CH(2)OH moieties in 7 and 9. Trace amounts of Ru(CO)(xantphos)(OC(6)H(4)O), a catecholate complex, are isolated from the reaction of 18 with 1. Improved syntheses of 18 and lignin models are also presented.

Abstract  The nature of oxygen particles produced in low-temperature desorption from V(2)O(5) and V(2)O(5) center dot MoO(3) was studied. It was found that there was no low-temperature desorption from samples in the presence of a quartz trap cooled to -195 degrees C, which was evidence of the absence of possible desorption of O(3) and the presence of (1)Delta(g) O(2). Under these conditions, the latter was frozen completely, and ozone was not.

Abstract  Spent samples of V(2)O(5)/SiO(2)-gamma Al(2)O(3) catalyst used for H(2)SO(4) production were acid treated to recover vanadium. Fresh, spent, and acid treated samples were characterized by temperature-programmed techniques: TPR-H(2), TPO-O(2), TPD-NH(3) and, TGA-DTA in order to determine the effect of deactivating species on vanadium recovery. DRX and UV-Vis techniques were used to confirm several signals from the temperature-programmed profiles. The results suggest that vanadium sulfovanadates and oxides in treated samples strongly interact with the support making it difficult to get more than 86% vanadium recovery.

Abstract  Using SiO(2), activated carbon (AC) and Al(2)O(3) as supports, the supported photocatalysts Ni-V-O/SiO(2), Ni-V-O/AC and Ni-V-O/Al(2)O(3) were prepared by impregnation method, and their spectralsignatures were investigated. The carbonylation of methanol with CO(2) under UV irradiation was used as a probe reaction to compare the photocatalytic performance of the prepared catalysts. Integrated with the testing results of carbonylation, the effects of different supports on selectivity for the carbonylation products of methyl formate (MF) and dimethyl carbonate (DMC) were discussed by pyridine-IR and UV-Vis techniques. XRD results showed that the particles of nickel and vanadium supported on SiO(2) had the highest degree of dispersion. Results of pyridine-IR indicated that all catalysts retained Lewis acid sites. The acid strength was different from catalyst samples with different supports but with the same active components. The acid strengths could be arranged as follows; Ni-V-O/SiO(2)> Ni-V-O/Al(2)O(3)>Ni-V-O/AC. Different acid strengths exhibited different influence on the selectivity of products MF and DMC of carbonylation. The surface acid strengths of catalysts were the major factor influencing the selectivity of carbonylation products.

Abstract  OBJECTIVE: To determine the levels of 24 minerals in human milk by inductively coupled plasma mass spectrometry with microwave digestion.

METHODS: The samples were digested by microwave. The contents of minerals were determined by inductively coupled plasma mass spectrometry. The standard reference minerals of 1849a and 1568a from National Institute of Science and Technology were used for quality control. The accuracy and reproduability for this method were evaluated with mix standards and 1849a and 1568a standard reference materials.

RESULTS: The ranges of the levels of sodium, magnesium, phosphorus, potassium, calcium, aluminum, chromium, arsenic, selenium, iron, zinc, manganese, copper, molybdenum, vanadium, cobalt, nickel, gallium, cadmium, silver, strontium, cesium, barium, lead in human milk was 34.97-415.83 mg/kg, 19.00-39.52 mg/kg, 102.13-274.53 mg/kg, 351.19-713.99 mg/kg, 180.08-349.64 mg/kg, 0.06-0.44 mg/kg, 0.9-7.37 microg/kg, 0.92-2.72 microg/kg, 0.20-21.15 microg/kg, 0.10-0.70 mg/kg, 0.56-3.25 mg/kg, 3.00-16.12 micro.g/kg, 62.16-591.69 microg/kg, 0.02-6.91 microg/kg, 5.99-13.70 microg/kg, 0.07-2.11 microg/kg, 0.77-209.26 microg/kg, 0.005-0.28 microg/kg, 0.02-0.23 microg/kg, 0.02-0.71 microg/kg, 36.89-132.26 microg/kg, 0.01-4.72 microg/kg, 0.83-28.16 microg/kg, 2.5-5.3 microg/kg, respectively. The levels of minerals in human milk in present study were consisted with other similar studies.

CONCLUSION: The experiment examined the levels of minerals in human milk satisfactorily. The method has high accuracy and good reproducibility, which could be used for understanding the levels of minerals in human milk.

Abstract  Background: Titanium is the most widely used metal in dental implantology. The release of particles from metal structures into the biologic milieu may be the result of electrochemical processes (corrosion) and/or mechanical disruption during insertion, abutment connection, or removal of failing implants. The aim of the present study is to evaluate tissue response of human oral mucosa adjacent to titanium cover screws. Methods: One hundred fifty-three biopsies of the supra-implant oral mucosa adjacent to the cover screw of submerged dental implants were analyzed. Histologic studies were performed to analyze epithelial and connective tissue as well as the presence of metal particles, which were identified using microchemical analysis. Langerhans cells, macrophages, and T lymphocytes were studied using immunohistochemical techniques. The surface of the cover screws was evaluated by scanning electron microscopy (SEM). Results: Forty-one percent of mucosa biopsies exhibited metal particles in different layers of the section thickness. Particle number and size varied greatly among specimens. Immunohistochemical study confirmed the presence of macrophages and T lymphocytes associated with the metal particles. Microchemical analysis revealed the presence of titanium in the particles. On SEM analysis, the surface of the screws exhibited depressions and irregularities. Conclusions: The biologic effects seen in the mucosa in contact with the cover screws might be associated with the presence of titanium or other elements, such as aluminum or vanadium. The potential long-term biologic effects of particles on soft tissues adjacent to metallic devices should be further investigated because these effects might affect the clinical outcome of the implant. J Periodontol 2012;83:973-980.

Abstract  In this paper electrical and optical properties of mixed titanium and vanadium oxides (Ti-V oxides) thin films have been outlined. Thin films were deposited by sputtering of mosaic Ti-V target in reactive oxygen plasma using high energy magnetron sputtering process. From elemental analysis results, 19 at.% of vanadium was incorporated into thin films and X-ray diffraction investigations displayed their amorphous behavior. However, images obtained by the use of an atomic force microscope displayed a densely packed nanocrystalline structure. It has been found that V addition considerably improves the electrical conduction of prepared Ti-V oxide thin films as compared to undoped TiO2 and results in p-type electrical conduction. Resistivity of Ti-V oxides thin films was found at the order of 10(5)Omega cm. Optical measurements have shown the average transmission coefficient of about 73% in the visible spectral range and that the position of fundamental absorption edge has been shifted by 40 nm towards the longer wavelength as compared to the undoped TiO2. The results testified that the prepared Ti-V oxides thin films might be considered as a p-type transparent oxide semiconductors for future application in transparent electronics. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  We review the state of the art and explain the need for better SO2 oxidation catalysts for the production of sulfuric acid. A high-throughput technology has been developed for the study of potential catalysts in the oxidation of SO2 to SO3. High-throughput methods are reviewed and the problems encountered with their adaptation to the corrosive conditions of SO2 oxidation are described. We show that while emissivity-corrected infrared thermography (ecIRT) can be used for primary screening, it is prone to errors because of the large variations in the emissivity of the catalyst surface. UV-visible (UV-Vis) spectrometry was selected instead as a reliable analysis method of monitoring the SO2 conversion. Installing plain sugar absorbents at reactor outlets proved valuable for the detection and quantitative removal of SO3 from the product gas before the UV-Vis analysis. We also overview some elements used for prescreening and those remaining after the screening of the first catalyst generations.

Abstract  A review, with 33 refs., of authors' own studies on the recovery of V and K compds. and SiO2 from spent V catalysts used for SO2-to-SO3 oxidn. Methods for immobilization of the catalyst components in deposited waste were also presented.

Abstract  Spent V2O5 catalysts for SO2-to-SO3 oxidn. were leached with 15% KOH soln., dried at 120 degrees C or calcd. at 400 degrees C and used for prodn. of fresh V catalysts. The decrease in fresh catalyst activity (as compared with catalysts supported on fresh SiO2) was lower for the calcd. SiO2 supports than for the dried ones.

Abstract  Ecotoxicological studies, using the tropical marine diatom, Nitzschia closterium (72-h growth rate), were undertaken to assess potential issues relating to the discharge from an alumina refinery in northern Australia. The studies assessed: (i) the species' upper thermal tolerance; (ii) the effects of three signature metals, aluminium (Al), vanadium (V) and gallium (Ga) (at 32°C); and (iii) the effects of wastewater (at 27 and 32°C). The critical thermal maximum and median inhibition temperature for N. closterium were 32.7°C and 33.1°C, respectively. Single metal toxicity tests found that N. closterium was more sensitive to Al compared to Ga and V, with IC(50)s (95% confidence limits) of 190 (140-280), 19,640 (11,600-25,200) and 42,000 (32,770-56,000) μg L(-1), respectively. The undiluted wastewater samples were of low toxicity to N. closterium (IC(50)s>100% wastewater). Environmental chemistry data suggested that the key metals and discharge are a very low risk to this species.

Abstract  An integrated assessment of biological activity and ecotoxicity of fluvial sediments in the Marcal river catchment (3078 km(2)), western Hungary, is presented following the accidental spill of bauxite processing residue (red mud) in Ajka. Red mud contaminated sediments are characterised by elevated pH, elevated trace element concentrations (e.g. As, Co, Cr, V), high exchangeable Na, and induce an adverse effect on test species across a range of trophic levels. While background contamination of the river system is highlighted by adverse effects on some test species at sites unaffected by red mud, the most pronounced toxic effects apparent in Vibrio fischeri bioluminescence inhibition, Lemna minor bioassay and Sinapis alba root and shoot growth occur at red mud depositional hotspots in the lower Torna Creek and upper Marcal. Heterocypris incongruens bioassays show no clear patterns, although the most red mud-rich sites do exert an adverse effect. Red mud does however appear to induce an increase in the density of aerobic and facultative anaerobic bacterial communities when compared with unaffected sediments and reference sites. Given the volume of material released in the spill, it is encouraging that the signal of the red mud on aquatic biota is visible at a relatively small number of sites. Gypsum-affected samples appear to induce an adverse effect in some bioassays (Sinapis alba and Heterocypris incongruens), which may be a feature of fine grain size, limited nutrient supply and greater availability of trace contaminants in the channel reaches that are subject to intense gypsum dosing. Implications for monitoring and management of the spill are discussed.

Abstract  A total of 94 (54 males, 40 females) healthy adult residents living in an industrial city in northern Taiwan were recruited to study their exposure to industrial metals by measuring their blood levels of V, Cr, Mn, Ni, Co, As, Se, Mo, Cd, Pb, and W. All participants were non-smokers without obvious direct occupational exposure to these elements, although by working in administrative sectors in industrial facilities their indirect or potential exposure was increased. The average concentrations of V, Cr, Mn, Ni, Co, As, Se, Mo, Cd, Pb, and W in blood were 0.30, 1.49, 15.1, 3.84, 2.73, 21.1, 204, 3.2, 0.76, 51.1, and 0.40 ng/mL, respectively. These values were significantly higher than reference values reported for the general population, in some cases exceeding those of occupationally exposed workers. The principal component and correlation analyses among blood element levels suggested that the predominant sources of exposure were glass manufacturing and traffic-related sources. Despite of some limitations, the study demonstrates that the residents in this industrial area may suffer adverse chronic health effects attributable to exposures to these elements.

Abstract  A review, with 18 refs., of literature data on surface and bulk properties of Fe-contg. V catalysts and their activity in oxidn. of SO2.

Abstract  Four samples of com. V catalysts were taken from an industrial plant for manufg. H2SO4 (fresh and after 1-3 yr of operation) and analyzed for V2O2, K2O and Fe contents, for porosity and for activity in SO2 oxidn. at 380-620 degrees C. The presence of F compds. and moisture in the gas phase resulted in the catalyst deactivation.

Abstract  Nitrogenase catalyzes the biological conversion of atmospheric dinitrogen to bioavailable ammonia. The molybdenum (Mo)- and vanadium (V)-dependent nitrogenases are two homologous members of this metalloenzyme family. However, despite their similarities in structure and function, the characterization of V-nitrogenase has taken a much longer and more winding path than that of its Mo-counterpart. From the initial discovery of this nitrogen-fixing system, to the recent finding of its CO-reducing capacity, V-nitrogenase has proven to be a two-hit wonder in the over-a-century-long research of nitrogen fixation. This perspective provides a brief account of the catalytic function and structural basis of V-nitrogenase, as well as a short discussion of the theoretical and practical potentials of this unique metalloenzyme.

Abstract  V-Mo-W mixed oxides are prepared by a hydrochemical preparation route with a stoichiometry of V(2)Mo(8)W(x)O(y) with 0 <= x <= 5 via evaporation/crystallization and by spray-drying of ammonium polyoxometallate solutions combined with a subsequent calcination procedure. The phase composition has been examined by electron and X-ray powder diffraction. Significant changes are observed after reduction/reoxidation and after/during reactions in an air-acrolein atmosphere for all crystalline samples. Samples prepared from spray-dried precursors with tungsten contents x > 1 are amorphous/nanocrystalline. Independent of the preparation and reaction procedure, the formation of the thermodynamically metastable, tetragonal Mo(5)O(14) phase is detected. Deactivation starts at the latest at 723 K in air with the formation of thermodynamically stable phases like orthorhombic MoO(3). Smaller particles exhibit higher stability against deactivation or reduction. Reaction networks are established to illustrate the effect of various chemical reactions on crystalline and amorphous/nanocrystalline structures. The temperatures of the industrial processes are interpreted on the basis of the presented results. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  The efficacy of chelating agents for treating acute vanadyl-sulfate (27774136) intoxication was studied in mice. Swiss-albino-mice were injected intramuscularly with 215 to 4640mg/kg vanadyl-sulfate as the pentahydrate. They were injected 10 minutes later with one of 18 chelating or reducing agents at concentrations of up to 804mg/kg. Fourteen day mortality was recorded to determine the median lethal doses (LD50s). The effectiveness of the agents was assessed by determining the therapeutic efficiency (TEF), the ratio of the LD50 for the combined treatment to the LD50 of vanadyl-sulfate alone. EDTA, glutathione, succinic-acid, monosodium-phosphate, diethylenetriaminepentaacetic-acid (DTPA), and 2-mercaptosuccinic-acid (2MC) enhanced survival and had TEFs above 1.00. Mice were injected with 334mg/kg vanadyl-sulfate followed 10 minutes later by EDTA, glutathione, succinic-acid, monosodium-phosphate, DTPA, 2MC, deferoxamine-mesylate, ascorbic-acid, or Tiron to examine their effects on urinary and fecal excretion and the tissue distribution of vanadium (7440622). Urine was the major route for vanadium excretion, 33% of the dose being excreted over 24 hours. Tiron, ascorbic-acid, and 2MC significantly increased urinary excretion of vanadium. The largest concentration of vanadium was found in the kidney, followed by the liver, spleen, heart, and brain, in that order. Tiron, EDTA, and 2MC significantly decreased vanadium concentrations in the kidney. Tiron and DTPA significantly decreased liver vanadium concentrations. EDTA, glutathione, monosodium-phosphate, Tiron, and DTPA decreased vanadium concentrations in the heart. None of the compounds significantly affected brain aluminum concentration. The authors conclude that Tiron is the most effective agent of those tested for removing vanadium after treatment with vanadyl-sulfate.

Abstract  Efficient lithium-ion batteries will play an important role within the development of future mobile and stationary applications such as portable microsystems, high power electric vehicles or high energy storage devices. All applications strongly require an improvement of the materials used in electrochemical cells in order to increase stability, power and energy density as well as cell lifetime. To challenge this demand, the development of future cell systems is mainly focused on the composition of solid electrolytes as well as on powerful rechargeable lithium-ion intercalation electrodes consisting out of nano-composite materials. In this work, thin film electrodes based on lithium manganese oxide compounds were deposited by radiofrequency magnetron sputtering on steel and silicon substrates. Within a new technical approach, UV-laser process technologies using a wavelength of 248 nm were applied in order to form three-dimensional cathode structures. Rapid laser annealing processes operating at 940 nm were performed to adjust an appropriate crystalline phase. Phase and structural analysis was performed using Raman spectroscopy, X-ray diffraction and electrochemical testing. The principle set-up of a three-dimensional all-solid state cell was shown by sputtering of lithium vanadium silicon oxide electrolyte and aluminium anode material on top of the lithium manganese oxide 3D structures. DOI: 10.2961/jlmn.2012.01.0019