Abstract  In this study, nano-crystalline vanadium carbide was synthesized through reduction of V2O5 by carbon and Ca using high energy ball milling and subsequent heat treatment. Vanadium pentoxide, calcium and carbon black were placed in a planetary ball mill and sampled after different milling times. The activated powders were synthesized by microwave heating at temperatures 800 degrees C. XRD and FESEM were used for characterization of synthesized powder. On the basis of obtained results, the synthesized V8C7 crystallites were in the scale of nanometers and the lattice parameter had some deviation from the standard value. Furthermore, investigations showed that at higher milling time, the amorphization degree of V4C3 phase increased, while the degree of crystallite decreased. Crown Copyright (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. All rights reserved.

Abstract  This paper presents the characterization studies conducted by Milwaukee School of Engineering senior undergraduate students in South Africa under the Research Experiences for Undergraduates grant EEC-1460183 sponsored by the National Science Foundation (Principal Investigator Dr. Kumpaty). Robert Mueller and Christopher Reynolds conducted research in summer of 2015 under advisement of Dr. Kumpaty and his South African collaborators, Dr. Esther Akinlabi and Dr. Sisa Pityana. The foreign collaborators' excellent support was pivotal to the success of our U.S. students.

Ti-6Al-4V is a titanium alloy that accounts for about 80% of the titanium market. The Ti-64 alloy contains 6 wt% Aluminum and 4 wt% Vanadium, an almost equal ratio of alpha + beta phases. Through the laser surface modification process known as Laser Meal Deposition, this alloy offers the optimum combination of enhanced properties. This research focuses on the application of adding a combination of molybdenum (Mo) and Ti-64 powders to a Ti-64 substrate surface in order to improve the durability for various biomedical/aerospace applications. Deposition of the powders was completed at the CSIR - National Laser Center, in Pretoria, South Africa. The characterization studies were carried out at the University of Johannesburg. The results of the hardness tests showed that the addition of molybdenum to Ti-64 increased the hardness of the deposited material compared to that of the substrate. This verifies that the addition of Mo to metals can affect the mechanical properties to better suit various applications.

While Robert Mueller studied the effect of laser power on the properties of laser metal deposited Ti-6Al-4V + Mo for wear resistance enhancement, Christopher Reynolds investigated scanning velocity influence on the evolving properties of laser metal deposited Ti-6Al-4V + Mo. The results of this promising research and various options for further investigation are presented. The beneficial value of such a global research enterprise on the budding engineers will be apparent and the paper details the process of the international component of the Research Experiences for Undergraduates.

Abstract  V(0.5)Mo(0.5)Nx/MgO(001) alloys with the B1-NaCI structure are grown by ultra-high-vacuum reactive magnetron sputter deposition in 5 mTorr mixed Ar/N-2 atmospheres at temperatures T-s between 100 and 900 degrees C. Alloy films grown at T-s <= 500 degrees C are polycrystalline with a strong 002 preferred orientation; layers grown at T-s >= 700 degrees C are epitaxial single-crystals. The N/Metal composition ratio x ranges from 1.02 +/- 0.05 with T-s = 100-500 degrees C to 0.94 +/- 0.05 at 700 degrees C to 0.64 +/- 0.05 at T-s = 900 degrees C. N loss at higher growth temperatures leads to a corresponding decrease in the relaxed lattice parameter a(0) from 4.212 A with x = 1.02 to 4.175 angstrom at x = 0.94 to 4.120 angstrom with x = 0.64. V(0.5)Mo(0.5)Nx nanoindentation hardnesses H and elastic moduli E increase with increasing T-s, from 17 +/- 3 and 323 +/- 30 GPa at 100 degrees C to 26 +/- 1 and 370 +/- 10 GPa at 900 degrees C. Both polycrystalline and single-crystal V(0.5)Mo(0.5)Nx films exhibit higher toughnesses than that of the parent binary compound VN. V(0.5)Mo(0.5)Nx films deposited at higher Ts also exhibit enhanced wear resistance. Valence-band x-ray photoelectron spectroscopy analyses reveal an increased volume density of shear-sensitive d-t(2g) d-t(2g) metallic states for V(0.5)Mo(0.5)Nx compared to VN and the density of these orbitals increases with increasing deposition temperature, i.e., with increasing N-vacancy concentration.(C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Abstract  We report the fabrication and properties of high performance and inexpensive composite membranes of sulfonated polyimide (SPI) and sulfonated molybdenum disulfide (s-MoS2) for the vanadium redox flow battery (VRFB) application. Scanning electron microscopy (SEM) images reveal the uniformity of SPI/s-MoS2 membrane. Both EDS and XRD results verify the existence of s-MoS2 in SPI/s-MoS2 membrane and show the interaction between SPI and s-MoS2. The physico-chemical properties of as-prepared SPI/sMoS(2) membrane, including water uptake and ion exchange capacity, etc. are evaluated and compared to those of SPI SPI/MoS2 and Nafion 117 membranes, respectively. The SPI/s-MoS2 membrane possesses increased proton conductivity and reduced vanadium ion permeability than pure SPI membrane, and it has the highest proton selectivity (2.24 x 10(5) S min cm(-3)) among all membranes. The VRFB with SPI/sMoS(2) membrane presents a higher coulombic efficiency (CE) and energy efficiency (EE) compared with Nafion 117 at the current density ranging from 20 to 80 mA cm(-2). The SPI/s-MoS2 membrane shows a longer discharge time (193 h above 0.8 V) than Nafion 117 (72 h). Moreover, the SPlis-MoS2 membrane exhibits stable operation performance up to 500 cycles with no significant decline in CE and EE. All experimental results confirm that the SPI/s-MoS2 membrane is suitable for use in VRFB. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  An efficient catalytic process for the oxidative dehydrogenation of biomass-derived lactic acid by earthabundant MoO3/TiO2 mixed oxide catalysts is presented. A series of MoO3/TiO2 materials with varied MoO3 loadings were prepared and their performance in the aerobic and anaerobic conversion of lactic acid was evaluated. A strong synergistic effect between MoO3 and TiO2 components of the mixed oxide catalyst was observed. Optimum catalysts in terms of activity and pyruvic acid selectivity can be obtained by ensuring a high dispersion of MoOx species on the titania surface. Mo-oxide aggregates catalyze undesired side-reactions. XPS measurements indicate that the redox processes involving supported Mo ions are crucial for the catalytic cycle. A mechanism is proposed, in which lactic acid adsorbs onto basic sites of the titania surface and is dehydrogenated over the Mo=O acid-base pair of a vicinal tetrahedral Mo site. The catalytic cycle closes by hydrolysis of surface pyruvate and water desorption accompanied by the reduction of the Mo center, which is finally oxidized by O-2 to regenerate the initial active site. Under anaerobic conditions, a less efficient catalytic cycle is established involving a bimolecular hydrogen transfer mechanism, selectively yielding propionic and pyruvic acids as the major products. The optimum catalyst is 2 wt% MoO3/TiO2 predominantly containing tetrahedral Mo species. With this catalyst the oxidative conversion of lactic acid at 200 degrees C proceeds with a selectivity of ca. 80% to pyruvic acid. The pyruvic acid productivity is 0.56 g g(-1) h(-1).

Abstract  Focused ion beam scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller gas adsorption methods have been used for the characterisation of physical properties of microporous carbide-derived carbon electrodes, prepared from Mo2C at 600 A degrees C (noted as Mo2C-CDC) before and after electrochemical tests conducted within a very wide two-electrode cell potential region. Cyclic voltammetry, constant current charge/discharge and impedance data have been analysed to establish the electrochemical characteristics of the hybrid devices consisting of the 1 M Na2SO4 and 1 M Rb2SO4 aqueous electrolytes and Mo2C-CDC electrodes within the very wide cell potential region (Delta E a parts per thousand currency signaEuro parts per thousand 2.4 V). The influence of cation chemical composition on the electrochemical characteristics of supercapacitors/electrochemical hybrid devices has been analysed. The complex kinetics behaviour of completed devices (adsorption, blocking adsorption and intercalation of Na+ and Rb+ ions; faradic and mass transfer; gas adsorption; etc.) has been established at Delta E a parts per thousand yenaEuro parts per thousand 1.5 V. At least three different characteristic time constants dependent on the electrolyte cation composition and cell potential applied have been established.

Abstract  Neutral bis(pentalene) metal sandwich compounds have been synthesized for the first row transition metals titanium and iron. In this connection, the complete series of first row transition metal bis(pentalene) metal complexes (C(8)H(6))(2)M (M = Ti, V, Cr, Mn, Fe, Co, Ni) has now been investigated by density functional theory in order to evaluate the effect of the metal electronic requirements on the hapticity of the pentalene ligands. The lowest energy structure for the titanium complex is the 18-electron complex (eta(8)-C(8)H(6))(eta(6)-C(8)H(6))Ti with one octahapto and one hexahapto pentalene ligand rather than the previously suggested 20-electron complex (eta(8)-C(8)H(6))(2)Ti with two octahapto pentalene ligands. The experimental NMR observations on (C(8)H(6))(2)Ti can then be reinterpreted as interchange of octahapto and hexahapto bonding of the pentalene units through a low energy bis(octahapto) (eta(8)-C(8)H(6))(2)Ti transition state. The lowest energy structure for (C(8)H(6))(2)V has two fulvene-like hexahapto pentalene ligands and a local vanadium environment similar to the well-known dibenzenevanadium. The lowest energy structures of the later first row transition metals have two pentahapto pentalene ligands with local metal environments similar to those in the corresponding metallocenes. In the manganese and iron structures of this type, the remaining unpaired electrons on one of the uncomplexed carbon atoms in each eta(5)-C(8)H(6) system form a C-C single bond to couple the two pentalene ligands. This coupling of the two pentalene systems through a C-C single bond is similar to that found experimentally by X-ray crystallography in bis(pentalene) iron, (eta(5)-C(8)H(6))(2)Fe.

Abstract  A method for the simultaneous determination of aluminum (Al), arsenic (As), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), phosphorus (P), lead (Pb), sulfur (S), selenium (Se), vanadium (V), and zinc (Zn) in organic soil amendments using microwaveassisted acid digestion and inductively coupled plasma optical emission spectroscopy (ICP OES) is proposed. Concentrated or diluted acids mixtures (HNO3, HF, HBF4, and H3BO3) combined or not with H2O2 were systematically evaluated in order to achieve the best digestion procedure for masses of around 150 mg of samples. Principal component analysis (PCA) was applied in order to choose the best acid mixture for digestion (3 mL HNO3 + 1 mL HBF4 + 2 mL H2O). The determined concentrations were in accordance with certified values of CRM 029 at the 95% confidence level, according to the Student-t test. This acid mixture was successfully applied for the digestion of four organic soil amendment samples (organic fertilizers, substrates, and soil conditioners) and element determination.

Abstract  Transitional metal carbides have great potential to overcome the shortcomings of high cost and rare sources of precious metal based catalysts. In this paper, we report the catalytic performances of commercial vanadium carbide (VC) and the influences of nitrogen doping on its catalytic performance towards oxygen reduction reactions. Results showed that nitrogen has been doped into the crystal lattice of commercial VC with a slight increase of crystalline size. The half-wave potential of oxygen reduction of the commercial VC and nitrogen doped VC was only 0.06 V and 0.04 V lower than that of Pt/C catalyst, respectively. The stability of VC for catalyzing oxygen reduction could be improved by nitrogen doping. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Abstract  Our recent exploration of the Pb-Ni-Se-O "crystallization phase diagram" under hydrothermal conditions has led to the discovery of three new selenites. Here we have applied a similar systematic method to the Pb-V-Se-O system using both hydrothermal and chemical vapor transport crystal growth using either PbO or PbCl2 as the source of lead. In our approach, phases in the presence are meticulously characterized by single crystal X-ray diffraction tests, on the basis of their morphology. Besides the determination of stable predominant phases in the diagram such as Pb-2(VO3)-, (SeO3)(2)Cl, it enables the crystallization of three novel vanadate selenites, beta-(V25+O3)(SeO3)(2) Pb-2(V4+O)(SeO3)(3) (II), and beta-Pb-4(V35+O8)(2)(SeO3)(3)(H2O) (III), depending on the method, pH, and potential of the solution. It is worth noting that in our conditions the solid/liquid crystal growth could be driven by kinetic or thermodynamic control which does not lead to determination of a formal phase diagram, but rather to a "solid phase space". The crystal structure of (I) is based on vanadate tetramers linked by selenite groups into a layer. The crystal structures of, and contain one-dimensional structural units composed of vanadate polyhedra and selnite groups interlinked through divalent read cations into a three-dimensional frameworks. The full panorama of reported lead vanadate selenites including our phases shows atypical polymorphic relations discussed on the basis of the structural complexity, very atypical among the polymorphic variations.

Abstract  Metal carbonyl cations of the form M(CO)(n)(+) are produced in a molecular beam by laser vaporization in a pulsed nozzle source. These ions, and their corresponding rare gas atom "tagged" analogs, M(CO)(n)(RG)(m)(+) are studied with mass-selected infrared photodissociation spectroscopy in the carbonyl stretching region and with density functional theory computations. The number of infrared-active bands, their frequency positions, and their relative intensities provide distinctive patterns allowing determination of the geometries and electronic structures of these complexes. Cobalt penta carbonyl and manganese hexacarbonyl cations are compared to isoelectronic iron pentacarbonyl and chromium hexacarbonyl neutrals. Gold and copper provide examples of "non-classical" carbonyls. Seven-coordinate carbonyls are explored for the vanadium group metal cations (V(+), Nb(+) and Ta(+)), while uranium cations provide an example of an eight-coordinate carbonyl. (C) 2011 Elsevier Inc. All rights reserved.

Abstract  DFT studies on the early transition metal (C8F8)(2)M derivatives (M = Ti, V, Cr) predict the two C8F8 rings to have only 12 of the 16 carbon atoms of the two C8F8 rings bonded to the metal, thereby leading to 16-, 17-, and 18-electron metal configurations, respectively. The lowest energy structure of the titanium derivative Ti(C8F8)(2) is predicted to have a singlet spin state with an octahapto and a tetrahapto C8F8 ring similar to the experimentally known hydrocarbon analog (eta(4)-C8H8)Ti(eta(8)-C8H8). However, the lowest energy structures for the vanadium and chromium analogs are bis(hexahapto) structures M(eta(6)-C8F8)(2) (M = V, Cr) rather than the octahapto-tetrahapto structures (eta(4)-C8H8)M(eta(8)-C8H8) predicted for the hydrocarbon analogs and found experimentally for V(C8H8)(2). The transition metals from vanadium to iron are predicted to form tetrahapto-hexahapto derivatives (eta(4)-C8H8)M(eta(6)-C8H8) (M = V, Cr, Mn, Fe) in which 10 of the 16 carbon atoms of the two C8F8 rings are within bonding distance of the central metal. For the iron complex two types of tetrahapto bonding are found for the tetrahapto C8F8 ring in singlet (eta(4)-C8H8)Fe(eta(6)-C8H8) structures of essentially equal energies. For the late transition metal cobalt the lowest energy (C8F8)(2)Co structure is a doublet bis(tetrahapto) structure in which four adjacent carbon atoms of each C8F8 ring are bonded to the cobalt atom as a cis-diene. The lowest energy (C8F8)(2)Ni structure has only six carbon atoms of the two C8F8 rings within bonding distance of the nickel atom as two isolated C=C double bonds in one ring and only a single C=C double bond in the other ring. This gives the nickel atom only a 16-electron configuration similar to other zerovalent nickel complexes. The ligand exchange reactions 2C(8)H(8) + (C8F8)(2)M = 2C(8)F(8) + (C8H8)(2)M are predicted to be exothermic for all of the first row transition metals. This indicates that the C8F8 ligand is more weakly bonded to these metals than the C8H8 ligand in accord with the electron withdrawing effect of the ligand fluorine atoms. (C) 2013 Elsevier B.V. All rights reserved.

Abstract  A cascade, composed of (i) oxovanadium(V)-catalyzed oxidation of bromide by tert-butyl hydroperoxide and (ii) stereoselective 6-endo-bromocyclization, affords 3-bromo-2-aryl-2,6,6-trimethyltetrahydropyrans from styrene-type tertiary alkenols in synthetically useful yields. (E)-Alkenols add the bromo- and the alkoxy substituent anti-selectively across the double bond, indicating a bromonium ion-mechanism for the ring closure. 6-endo-control of the alkenol cyclization thereby arises from the polar effect of the aryl substituent. Two methyl substituents bound to the alkene terminus are not similarly able to favor 6-endocyclization, because strain arising from methyl group repulsion, as the bromonium-activated pi-bond and the hydroxyl oxygen approach, directs bromocyclization of tertiary prenyl-type substrates toward tetrahydrofuran formation. A hexasubstituted bromotetrahydropyran prepared from the oxidation/bromocyclization cascade served as starting material for synthesis of racemic aplysiapyranoid A, in a sequence of free radical and polar functional group interconversion. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract  Molecular bromine is formed from bromide and tert-butyl hydroperoxide under mild and neutral conditions. The oxidation is catalyzed by vanadium(V)-complexes and requires bromide- and proton- aliquots that are slowly released from a 3-bromopropionic acid-bromide buffer in solutions of alkyl carbonates. In such an environment, bromocyclization of acid labile alkenols occurs without hydrolytically cleaving acetal- or ester-protecting groups. 4-Pentenols having methyl- and/or phenyl-groups attached to the terminal carbon atom of the alkenol double bond undergo 6-endo-selective ring closures if subjected to oxidative bromination and provide bromotetrahydropyrans in synthetically useful yields. Application of the new procedure affords a hexasubstituted tetrahydropyran-building block en route to synthesis of the marine natural product aplysiapyranoid A.

Abstract  Two series of Cu2+ and V4+ doped anatase TiO2 samples were prepared using the microemulsion synthetic route by varying the metal/Ti ratio. The samples were characterized by UV-vis absorption, nitrogen physisorption, XRD, XPS, Raman and EPR spectroscopy. Their photocatalytic activity against toluene photooxidation was evaluated under both sunlight-type and pure UV light irradiation. The photoactivity was drastically affected by the dopant content. Low or moderate metal doping levels were beneficial for toluene photo-degradation, while high doping levels suppressed the photoactivity. Electron paramagnetic resonance (EPR) spectroscopy was employed to study the structure and electronic characteristics of the prepared catalysts and elucidate the physicochemical aspects governing the photoactivity. The presence of different Cu and V species was detected as a function of the metal content in the catalyst. EPR spectroscopy revealed that photoinitiated charge formation takes place in both the Cu and V doped TiO2 series and that charge separation may be enhanced depending on the dopant content. A direct correlation between the dopant species formed and hole formation was observed in both series. Photoactivity is directly correlated with the formation of holes, which in turn is tuned by the dopant content regulating the isolated metal centers versus metal cluster formation. Low or moderate doping levels enhanced the separation of photo-produced electron-hole pairs via accepting e(-), eliminating trapping sites related to localized Ti3+ states and increasing the abundance of hole species. At higher levels where metal clusters prevailed, dopants acted as recombination centers, deteriorating the photoactivity in both TiO2-doped series. The results indicate a general mechanism potentially applicable to similar photocatalytic systems.

Abstract  Nanostructures of V2O5 find important technological applications in optics, catalysis, and lithium ion batteries. Their optical properties and surface roughness are important parameters in these respects. Here we report on atomic layer deposition (ALD) of V2O5 using the beta-diketonate VO(thd)(2) and ozone as precursors. In this work, X-ray diffraction, AFM, ellipsometry, and UV-vis-spectroscopyare used to show that the crystallographic orientation, optical properties, band gap, and surface roughness of the derived films are correlated and can be varied by controlling deposition temperature and film thickness. The band gap of the samples varies between 2.70 and 2.35 eV. The observed growth rate varies between 0.1 to 1 angstrom/cycle depending on deposition temperature and the number of cycles. This large variation in growth rate provides an interesting case of ALD growth, which can be rationalized in terms of a geometric crystal growth model.

Abstract  Zinc/vanadium layered double hydroxide (LDH) was prepared and its functional relationships with thiourea were investigated in order to develop a sensor for the recognition of this toxin. Sensor technology is one of the major recognition methods and has shown potential applications in environmental monitoring, but issues of sensitivity, selectivity, and high cost related to this technology still need to be resolved in order to allow their more extensive use. Our study therefore focused on the development of a low-cost selective and sensitive thiourea sensor. This was developed using LDH where its sensing potential was investigated by a simple I-V technique. The developed sensor exhibited high sensitivity (1.004 mu A mu M cm(-2)), lower limit of detection (8.4 mu M) and wide range of linear dynamics (10-500 mu M). The selectivity was studied using different interfering agents and it was found that the developed sensor is more selective toward thiourea. The sensor behavior was further optimized using buffers of different pH. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Abstract  Synthesizing published data, we provide a quantitative summary of the global biogeochemical cycle of vanadium (V), including both human-derived and natural fluxes. Through mining of V ores (130 × 109 g V/y) and extraction and combustion of fossil fuels (600 × 109 g V/y), humans are the predominant force in the geochemical cycle of V at Earth's surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric flux probably derives from emissions from the combustion of fossil fuels, but the magnitude of this flux depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the flux of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced-with about 40 × 109 g V/y to 50 × 109 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.

Abstract  VO2(A) nanobelts have been synthesized using V2O5, H2O2, ethanol, H2O as the starting materials through a facile hydrothermal method. The as-obtained products were characterized by X-ray powder diffraction (XRD), X-ray photoelecton spectroscopy (XPS), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Some parameters, such as, the reaction time, reaction temperature and the ratio of EtOH/H2O, have greatly influenced on the phases and morphologies of the final products. It was found that VO2(A) can be converted to VO2(M) at 700 degrees C for 2 h for the first time. Furthermore, the phase transition properties of VO2(A) and VO2(M) phases were respectively studied.

Abstract  In this paper, new self-repairing vanadium-zirconium composite conversion coating was prepared and investigated by Electrochemical impedance spectra (EIS), Scanning electron microscope (SEM) and Xray photoelectron spectroscopy (XPS), respectively. EIS results showed that V-Zr conversion coating with hydrogen peroxide modified (VZO) revealed an increasing corrosion resistance in corrosive media which meant a certain self-repairing effect. SEM comparison photos also disclosed that VZO treated with scratches was gradually ameliorated from the initial cracked configuration to fewer cracks and more fillers through an immersion of 3.5% NaCl solution. XPS results demonstrated that the content of vanadium on VZO increased and zirconium declined when immersed in the corrosive solution. This explained further that the self-repairing ability could be related to vanadium. From the above results, we inferred possible structures of VZO and proposed that self-repairing effect was achieved through a hydrolysis condensation polymerization process of vanadate in the localized corrosion area. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

Abstract  Pollution by trace elements and its possible effect on organisms has become a worldwide concern due to the increasing presence of trace elements in the environment and especially in the food chain. Exposure to chemicals has traditionally been measured using environmental samples, however, human biomonitoring brings a different perspective, in which all sources and exposure pathways are integrated. The objective of this paper is to discern the possible relationship between children's diet and the metals found in children urine. With this aim in mind, a total of 120 voluntaries participated in a diet survey carried out in a school-aged population (age 6-11) from the Valencian region. In addition, twenty trace elements were analysed in children urine (arsenic, antimony, barium, beryllium, caesium, cadmium, cobalt, copper, lead, manganese, mercury, molybdenum, nickel, platinum, selenium, thallium, thorium, uranium, vanadium and zinc). Results permitted to compare metal levels in urine with metal levels of other biomonitoring studies to conclude that values, including ours, were similar in most studies. On the other hand, children who ate more vegetables had the highest values in cadmium, copper, molybdenum, antimony, thallium, vanadium, and zinc, while those who ate more fish reached higher values in mercury. Finally, children who ate more cereals and baked products had higher values in total arsenic.

Abstract  OBJECTIVE: Many metals, some of which have been classified as environmental endocrine disruptors, are used extensively in everyday consumer products and are ubiquitous in our living environment. In the present study, we aimed to explore the associations between the prevalence risk of type 2 diabetes and plasma levels of 20 trace elements as well as those of heavy metals in a Han Chinese population.

METHODS: We conducted a case-control study to investigate the associations between plasma concentrations of 20 metals and diabetes in Jiangsu province. A total of 122 newly diagnosed cases of type 2 diabetes and 429 matched controls were recruited from community physical examinations in Suzhou City of Jiangsu Province. Plasma metal levels were measured by inductively-coupled plasma mass spectrometry.

RESULTS: After adjusting for confounders, plasma vanadium, chromium, manganese, copper, zinc, arsenic, selenium, strontium, palladium, cadmium, cesium, and barium were associated with diabetes risk (P < 0.05). The adjusted OR increased with increasing concentration of vanadium, manganese, copper, zinc, and cesium.

CONCLUSION: Many metals, including manganese, copper, zinc, arsenic, selenium, and cadmium in plasma, are associated with the morbidity of diabetes. Monitoring of environmental metal levels and further studies are urgently needed.

Abstract  The development of reference values of trace elements is recognized as a fundamental prerequisite for the assessment of trace element nutritional status and health risks. In this study, a total of 1400 pregnant women aged 27.0 ± 4.5 years were randomly selected from the China Nutrition and Health Survey 2010-2012 (CNHS 2010-2012). The concentrations of 14 serum trace elements were determined by high-resolution inductively coupled plasma mass spectrometry. Reference values were calculated covering the central 95% reference intervals (P2.5-P97.5) after excluding outliers by Dixon's test. The overall reference values of serum trace elements were 131.5 (55.8-265.0 μg/dL for iron (Fe), 195.5 (107.0-362.4) μg/dL for copper (Cu), 74.0 (51.8-111.3) μg/dL for zinc (Zn), 22.3 (14.0-62.0) μg/dL for rubidium (Rb), 72.2 (39.9-111.6) μg/L for selenium (Se), 45.9 (23.8-104.3) μg/L for strontium (Sr), 1.8 (1.2-3.6) μg/L for molybdenum (Mo), 2.4 (1.2-8.4) μg/L for manganese (Mn), 1.9 (0.6-9.0) ng/L for lead (Pb), 1.1 (0.3-5.6) ng/L for arsenic (As), 835.6 (219.8-4287.7) ng/L for chromium (Cr), 337.9 (57.0-1130.0) ng/L for cobalt (Co), 193.2 (23.6-2323.1) ng/L for vanadium (V), and 133.7 (72.1-595.1) ng/L for cadmium (Cd). Furthermore, some significant differences in serum trace element reference values were observed between different groupings of age intervals, residences, anthropometric status, and duration of pregnancy. We found that serum Fe, Zn, and Se concentrations significantly decreased, whereas serum Cu, Sr, and Co concentrations elevated progressively compared with reference values of 14 serum trace elements in pregnant Chinese women. The reference values of serum trace elements established could play a key role in the following nutritional status and health risk assessment.

Abstract  Naturally occurring arsenic in groundwater exceeding the limit for potability has been reported along the southern edge of the Cenozoic Duero Basin (CDB) near its contact with the Spanish Central System (SCS). In this area, spatial variability of arsenic is high, peaking at 241μg/L. Forty-seven percent of samples collected contained arsenic above the maximum allowable concentration for drinking water (10μg/L). Correlations of As with other hydrochemical variables were investigated using multivariate statistical analysis (Hierarchical Cluster Analysis, HCA and Principal Component Analysis, PCA). It was found that As, V, Cr and pH are closely related and that there were also close correlations with temperature and Na+. The highest concentrations of arsenic and other associated Potentially Toxic Geogenic Trace Elements (PTGTE) are linked to alkaline NaHCO3waters (pH≈9), moderate oxic conditions and temperatures of around 18°C-19°C. The most plausible hypothesis to explain the high arsenic concentrations is the contribution of deeper regional flows with a significant hydrothermal component (cold-hydrothermal waters), flowing through faults in the basement rock. Water mixing and water-rock interactions occur both in the fissured aquifer media (igneous and metasedimentary bedrock) and in the sedimentary environment of the CDB, where agricultural pollution phenomena are also active. A combination of multivariate statistical tools and hydrochemical analysis enabled the distribution pattern of dissolved As and other PTGTE in groundwaters in the study area to be interpreted, and their most likely origin to be established. This methodology could be applied to other sedimentary areas with similar characteristics and problems.