Search Results (9)

The Huanggang iron-tin deposit, located in the southern Greater Khingan Range, is one of the largest Fe-Sn deposits in Northern China (NE China). Iron-tin mineralization occurs mainly in the contact zone between granitoid intrusions and the marble of the Huanggang and Dashizhai formations. Six mineralization stages are identified: (I) anhydrous skarn, (II) hydrous skarn, (III) cassiterite-quartz-calcite, (IV) pyrite-arsenopyrite-quartz-fluorite, (V) polymetallic sulfides-quartz, and (VI) carbonate ones. Fluid inclusions (FIs) analysis reveals that Stage I garnet and Stage II–III quartz host liquid-rich (VL-type), vapor-rich two-phase (LV-type), and halite-bearing three-phase (SL-type) inclusions. Stage IV quartz and fluorite, along with Stage V quartz, are dominated by VL- and LV-type inclusions, while Stage VI calcite contains exclusively VL-type inclusions. The FIs in Stages I to VI homogenized at 392–513, 317–429, 272–418, 224–347, 201–281, and 163–213 °C, with corresponding salinities of 3.05–56.44, 2.56–47.77, 2.89–45.85, 1.39–12.42, 0.87–10.62, and 4.48–8.54 wt% NaCl equiv., respectively. The H–O–C isotopes data imply that fluids of the anhydrous skarn stage (δD = −101.2 to −91.4‰, δ¹⁸O_H2O = 5.0 to 6.0‰) were of magmatic origin, the fluids of hydrous skarn and oxide stages (δD = −106.3 to −104.7‰, δ¹⁸O_H2O = 4.3 to 4.9‰) were characterized by fluid mixing with minor meteoric water, while the fluids of sulfide stages (δD = −117.4 to −108.6‰, δ¹⁸O_H2O = −3.4 to 0.3‰, δ¹³C_V-PDB= −12.2 to −10.9‰, and δ¹⁸O_V-SMOW = −2.2 to −0.7‰) were characterized by mixing of significant amount of meteoric water. The ore-forming fluids evolved from a high-temperature, high-salinity NaCl−H₂O boiling system to a low-temperature, low-salinity NaCl−H₂O mixing system. The garnet U-Pb dating constrains the formation of skarn to 132.1 ± 4.7 Ma (MSWD = 0.64), which aligns, within analytical uncertainty, with the weighted-mean U−Pb age of zircon grains in ore-related K-feldspar granite (132.6 ± 0.9 Ma; MSWD = 1.5). On the basis of these findings, the Huanggang deposit, formed in the Early Cretaceous, is a typical skarn-type system, in which ore precipitation was principally controlled by fluid boiling and mixing. Full article

Developing high-efficiency photoelectrodes plays an important role in the photoelectrocatalytic generation of hydrogen peroxide (H₂O₂) in the photoelectrochemical (PEC) water splitting field. In this work, an innovative strategy was proposed, the synergistic photocatalytic production of H₂O₂ using a bidirectional photoanode–photocathode coupling system under visible-light irradiation. Fe₂O₃-Ti, as the photoanode, which was built by way of Fe₂O₃ loaded on Ti-mesh using the hydrothermal-calcination method, was investigated in terms of the suitability of its properties for PEC H₂O₂ production after optimization of the bias voltage, the type of electrolyte solution, and the concentration of the electrolyte. Afterwards, a H-type double-electrode coupling system with an Fe₂O₃-Ti photoanode and a WO₃@Co₂SnO₄ photocathode was established for the bidirectional synergistic production of H₂O₂ under visible-light irradiation. The yield of H₂O₂ reached 919.56 μmol·L⁻¹·h⁻¹ in 2 h over −0.7 V with 1 mol·L⁻¹ of KHCO₃ as the anolyte and 0.1 mol·L⁻¹ Na₂SO₄ as the catholyte (pH = 3). It was inferred that H₂O₂ production on the WO₃@Co₂SnO₄ photocathode was in line with the 2e^- oxygen reduction reaction (ORR) principle, and on the Fe₂O₃-Ti photoanode was in line with the 2e^- water oxidation reaction (WOR) rule, or it was indirectly promoted by the electrolyte solution KHCO₃. This work provides an innovative idea and a reference for anode–cathode double coupling systems for the bidirectional production of H₂O₂. Full article

The Southern Hunan area is located in the superposition of the Qin-Hang Cu-Pb-Zn polymetallic ore belt and the Nanling W-Sn-Mo polymetallic ore belt, which is an important window to study the mineralization of W-Sn-Mo and Cu-Pb-Zn polymetallic deposits. The Baoshan deposit is a large Cu-Pb-Zn polymetallic deposit in Southern Hunan Province with obvious zones of Cu mineralization and Pb-Zn mineralization: the central part of the Baoshan deposit demonstrates contact metasomatic (skarn) Cu mineralization, while the western, northern and eastern parts demonstrate hydrothermal vein Pb-Zn mineralization. However, the origin and evolution of the ore-forming fluid and mechanism of Cu and Pb-Zn mineral precipitation are still unclear. The metallogenic process of the Baoshan Cu-Pb-Zn deposit can be divided into four stages: (1) the early skarn stage (S₁); (2) the late skarn stage (S₂); (3) the Cu-Fe sulfide stage (S₃); and (4) the Pb-Zn sulfide stage (S₄). The results of microtemperature measurements and a Raman spectrometric analysis of fluid inclusions show that the ore-forming fluid was the H₂O-NaCl (-CO₂ ± N₂ ± C₂H₆) system in the skarn stages (S₁ + S₂) and changed into the H₂O-NaCl-CO₂ (±N₂ ± C₂H₆) system in the sulfide stages (S₃ + S₄). The temperature (S₁: 436.6~548.2 °C; S₂: 344.1~435.1 °C; S₃: 134.1~413.1 °C; S₄: 183.9~261.0 °C) and salinity (S₁: 17.4~51.2 wt.%NaClequiv; S₂: 13.6~41.7 wt.%NaClequiv; S₃: 1.2~32.3 wt.%NaClequiv; S₄: 1.8~9.6 wt.%NaClequiv) showed a downward trend from the early to late stages. From the skarn stages (S₁ + S₂) to the sulfide stages (S₃ + S₄), the ore-forming pressure results from the static rock pressure and the hydrostatic pressure, and the ore-forming depth is estimated to be about three to six km. The C-H-O isotopic compositions of hydrothermal minerals such as quartz and calcite indicate that the ore-forming fluid is predominately magmatic fluid, but a significant amount of meteoric water is added in the Pb-Zn sulfide stage (S₄). The formation of the mineralization zonation of the Baoshan deposit is the result of many factors (e.g., stratigraphy, structure and metal precipitation mechanism): the Cu mineralization is controlled by the contact zone, and the Pb-Zn mineralization is controlled by the fault. In addition, the precipitation of Cu is mainly controlled by fluid boiling, while the precipitation of Pb and Zn is mainly controlled by the mixing of magmatic fluid and meteoric water. Full article

This review addresses the importance of Zn for obtaining multifunctional materials with interesting properties by following certain preparation strategies: choosing the appropriate synthesis route, doping and co-doping of ZnO films to achieve conductive oxide materials with p- or n-type conductivity, and finally adding polymers in the oxide systems for piezoelectricity enhancement. We mainly followed the results of studies of the last ten years through chemical routes, especially by sol-gel and hydrothermal synthesis. Zinc is an essential element that has a special importance for developing multifunctional materials with various applications. ZnO can be used for the deposition of thin films or for obtaining mixed layers by combining ZnO with other oxides (ZnO-SnO₂, ZnO-CuO). Also, composite films can be achieved by mixing ZnO with polymers. It can be doped with metals (Li, Na, Mg, Al) or non-metals (B, N, P). Zn is easily incorporated in a matrix and therefore it can be used as a dopant for other oxidic materials, such as: ITO, CuO, BiFeO_3, and NiO. ZnO can be very useful as a seed layer, for good adherence of the main layer to the substrate, generating nucleation sites for nanowires growth. Thanks to its interesting properties, ZnO is a material with multiple applications in various fields: sensing technology, piezoelectric devices, transparent conductive oxides, solar cells, and photoluminescence applications. Its versatility is the main message of this review. Full article

For effective supercapacitors, we developed a process involving chemical bath deposition, followed by electrochemical deposition and calcination, to produce WO₃/SnO₂ nanocomposite electrodes. In aqueous solutions, the hexagonal WO₃ microspheres were first chemically deposited on a carbon cloth, and then tin oxides were uniformly electrodeposited. The synthesized WO₃/SnO₂ nanocomposite was characterized by XRD, XPS, SEM, and EDX techniques. Electrochemical properties of the WO₃/SnO₂ nanocomposite were analyzed by cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy in an aqueous solution of Na₂SO₄ with/without the redox-active electrolyte K₃Fe(CN)₆. K₃Fe(CN)₆ exhibited a synergetic effect on the electrochemical performance of the WO₃/SnO₂ nanocomposite electrode, with a specific capacitance of 640 F/g at a scan rate of 5 mV/s, while that without K₃Fe(CN)₆ was 530 F/g. The WO₃/SnO₂ nanocomposite catalyzed the redox reactions of [Fe(CN)₆]³/[Fe(CN)₆]⁴⁻ ions, and the [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ ions also promoted redox reactions of the WO₃/SnO₂ nanocomposite. A symmetrical configuration of the nanocomposite electrodes provided good cycling stability (coulombic efficiency of 99.6% over 2000 cycles) and satisfied both energy density (60 Whkg⁻¹) and power density (540 Wkg⁻¹) requirements. Thus, the WO₃/SnO₂ nanocomposite prepared by this simple process is a promising component for a hybrid pseudocapacitor system with a redox-flow battery mechanism. Full article

In this study, the stable isotope, and elemental fingerprints of 120 meat samples were determined. The Partial Last Squares-Discriminant Analysis (PLS-DA) method was applied to build classification models for chicken and pork meat samples according to the geographical origin (different Romanian regions) and the animal growing system (animals coming from yard rearing systems versus animals coming from industrial farms). The accuracy of the geographical origin differentiation model was 93.8% for chicken and 71.8% for pork meat. The principal discrimination markers for this classification were: B, Na, K, V, As, Se, Rb, Nb, Cd, Sn, δ¹³C, δ²H, and δ¹⁸O (for chicken meat) and B, Na, Mg, K, Ca, V, Cr, Fe, Ni, Cu, Zn, As, Rb, Sr, Nb, Mo, Sn, Sb, Ba, Pb, δ¹³C, δ²H, and δ¹⁸O (for pork meat). The PLS-DA models were able to differentiate the meat samples according to the animal rearing system with 100% accuracy (for pork meat) and 98% accuracy (for chicken meat), based on the main predictors: B, K, V, Cr, Mn, Fe, Cu, Zn, Se, Rb, Nb, Sn, δ¹³C, and δ²H (for chicken meat) and Se, Rb, Nb, Sb, Ba, Pb, and δ¹³C (for pork meat). Full article

With the view of developing new materials for sodium and sodium-ion power sources, NaFeO₂-SnO₂ (0–50 mol.% SnO₂) powders were synthesized using a solid state method, and their phase composition and crystal structure were studied. A phase of the Na_0.8Fe_0.8Sn_0.2O₂ composition with a layered rhombohedral structure of the α-NaFeO₂ type was found when the tin dioxide content was 20 mol.%. The phase produced was of an O3 structural type. O3-type phases have sufficiently good performance when used as cathode materials in sodium-ion batteries and, moreover, often have a rather high sodium-cation conductivity. A two-dimensional migration map was built using Voronoi–Dirichlet partition and TOPOS software package. The sodium-ion conductivity of Na_0.8Fe_0.8Sn_0.2O₂ at room temperature was rated low (10⁻⁸ S × cm⁻¹ at 20 °C), which may be the result of channels too narrow for Na⁺ migration. The results obtained show that the application of the compound studied in this work as a solid electrolyte in sodium power sources is unlikely. It is the potential use of Na_0.8Fe_0.8Sn_0.2O₂ as the active material of cathodes in Na and Na-ion power sources that presents practical interest. Full article

The Podu Iloaiei Dam Lake located on the Bahluet River from Bahlui hydrographic basin, north-eastern Romania, is one of the most important water resources used for aquaculture activities in the region of interest. In the present study, the chemical composition related to water-soluble ions and elements was assessed in both water and sediment samples collected from the area of interest during July 2017 and October 2017, representative months for warm and cold seasons, respectively. Water-soluble ions (H₃C₂O₂⁻, HCO₂⁻, C₂O₄²⁻, F⁻, Cl⁻, NO₂⁻, Br⁻, NO₃⁻, SO₄²⁻, Li⁺, Na⁺, NH₄⁺, K⁺, and Ca²⁺) were analyzed by ion chromatography, while inductively coupled plasma mass spectrometry was used to quantify water-soluble fractions of elements (Be, B, Mg, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Mo, Ru, Pd, Ag, Cd, Sn, Sb, Te, Ba, Ir, Tl, Pb, Bi, and U). Evidence was obtained on the contributions of both anthropogenic and natural (pedologic) related sources in controlling the chemical composition of the water and sediment samples in the area. Analysis of Piper diagrams revealed the existence of CO₃²⁻/HCO₃⁻ and Ca²⁺/Mg²⁺ as dominant species for the sediment samples. The interest water pool was found to be oligotrophic over the warm period and eutrophic over the cold period. Overall, abundances and the association of chemical species in the area seemed to be controlled by a complex interplay between the water body’s main characteristics, meteorological factors, and anthropogenic activities. Moreover, the present results suggest that precautions should be taken for physicochemical parameter monitoring and prevention acts for surface water quality assurance in order to control the potential negative influence of some chemical parameters on fish productivity. Reported data also have a high potential to be used by experts in the field of developing lake water management policies for a sustainable exploitation of various aquatic systems. Full article

Tourmalines are a group of minerals which may concentrate various accessory components, e.g., Cu, Ni, Zn, Bi, Ti, and Sn. The paper presents fluor-elbaite and elbaite from a dyke of the Julianna pegmatitic system at Piława Górna, at the NE margin of the Bohemian Massif, SW Poland, containing up to 6.32 and 7.37 wt % ZnO, respectively. Such high amounts of ZnO are almost two times higher than in the second most Zn-enriched tourmaline known to date. The compositions of the Zn-rich tourmalines from Piława Górna, studied by electron micropropy and Raman spectroscopy, correspond to the formulae: ^X(Na_0.733Ca_0.013☐_0.254)_Σ1^Y(Al_1.033Li_0.792Zn_0.755Fe²⁺_0.326Mn_0.094)_Σ3^ZAl₆(^TSi₆O₁₈)(BO₃)₃^V(OH)₃^W(F_0.654OH_0.344), and ^X(Na_0.779Ca_0.015☐_0.206)_Σ1^Y(Al_1.061Li_0.869Zn_0.880Fe²⁺_0.098Mn_0.094)_Σ3^ZAl₆(^TSi₆O₁₈)(BO₃)₃^V(OH)₃^W(OH_0.837F_0.163), respectively, with Zn as one of the main octahedral occupants. A comparison with other tourmalines and associated Zn-rich fluor-elbaite and elbaite from the pegmatite indicates that atypically high Zn-enrichment is not a result of Zn-Fe fractionation, but dissolution and reprecipitation induced by a late (Na,Li,B,F)-bearing fluid within the assemblage of gahnite spinel and primary schorl-type tourmaline. This strongly suggests Na-Li-B-F metasomatism of gahnite-bearing mineral assemblages as that is the only environment that can promote crystallization of a hypothetical Zn-dominant tourmaline. The compositions of the Zn-rich fluor-elbaite and elbaite suggest three possible end-members for such a hypothetical tourmaline species: NaZn₃Al₆(Si₆O₁₈)(BO₃)₃(OH)₃(OH), ☐(Zn₂Al)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃(OH) and Na(Zn₂Al)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃O by analogy with other tourmalines with divalent Y occupants, such as schorl/foitite/oxy-schorl and dravite/magnesio-foitite/oxy-dravite. Full article