Zn Ratio Research Articles

NEW INSIGHT INTO THE EFFECT OF NOZZLE DIAMETER ON THE PROPERTIES OF SPRAYED ZnO THIN FILMS

Zinc oxide (ZnO) nanofibers and nanopetals were successfully deposited onto mesoporous silicon (meso-PSi), silicon, and glass substrates using zinc acetate via Spray Pyrolysis method. Electrochemical etching of the P-type (100) silicon wafer was used to prepare the mesoporous silicon layer. The effects of nozzle diameter and substrate type on the morphological, structural, and optical properties were investigated using XRD, SEM, EDX techniques, FT-IR, and UV-Vis spectrometry. Scanning Electron Microscopy (SEM) confirms the meso-PSi morphology with a diameter varying from 20[Formula: see text]nm to 45[Formula: see text]nm and illustrates the prepared ZnO nanostructures. EDX results show that the ratio of Zn:O is found to be similar to 1:1 for the 3-mm diameter when the oxygen is much higher than the Zn element in the 18-mm diameter. XRD measurements indicated that all films show a hexagonal Wurtzite structure with a variation of crystallographic properties and orientation according to the prepared morphology. The mean value of the crystallite size is 14.27[Formula: see text]nm for the 3-mm diameter and 19.01 nm for the 18-mm diameter. The variation in the morphological characteristics of the deposited ZnO leads to a variation in the optical properties of the sprayed ZnO thin films. The layers bandgap energy (Eg) was estimated to be 3.28 and 3.26[Formula: see text]eV for the ZnO layers prepared by 18-mm and 3-mm nozzle diameters, respectively. This study is also helpful for subsequent studies on the tailoring of morphology and ZnO growth control on PSi substrates.

Antifouling catalytic mixed-matrix membranes based on polyethersulfone and composition-optimized Zn-Cu-Fe-O CWAO catalyst under dark ambient conditions

ABSTRACT Besides photocatalysts, novel catalytic wet-air oxidation (CWAO) catalysts capable of operating under mild conditions are a potential candidate to fabricate antifouling filtration membranes. This study optimized the CWAO catalyst consisting of three metal oxide components (ZnO, CuO, and Fe3O4) and used it to fabricate composite membranes with PES (polyethersulfone). The catalyst was characterized by methods such as FTIR, BET, XRD, UV-Vis DRS, XPS, ESR. The activity of the catalyst and the composite membranes was tested by the Acid Yellow 42 (AY42) degradation experiments in both cases with and without hydrogen peroxide at room conditions with air aeration. The pure water fluxes of composite membranes were also investigated based on a vacuum filtration system. The major degradation pathways of AY42 by the catalyst were proposed from the DFT (Density Functional Theory) and NBO (Natural Bond Orbital) calculations. The results showed that the optimal catalyst has molar ratios of Zn, Cu, and Fe metal ions of 0.05, 0.588, and 0.362, respectively, with AY42 decomposition efficiency of 88% in 3 h. The main factors affecting the catalytic efficiency of the CWAO catalyst determined from the trapping experiment were e– and O2. The results from different materials characterization methods have demonstrated the successful synthesis of the catalyst with a high surface area (103.5 m2/g) and small pore diameters (∼10 nm). The AY42 degradation of composite membranes was stable over five repeated cycles with over 70% efficiency. The pure water fluxes of composite membranes have also been significantly improved and are proportional to catalyst contents.

Electronic Regulation of ZnCo Dual-Atomic Active Sites Entrapped in 1D@2D Hierarchical N-Doped Carbon for Efficient Synergistic Catalysis of Oxygen Reduction in Zn-Air Battery.

Transition metal-based nitrogen-doped carbon (M-Nx -C) is considered as a promising catalyst for the oxygen reduction reaction (ORR) in clean energy storage and conversion devices. Herein, ZnCo dual-atomic sites are incorporated in hierarchical N-doped carbon (HNC), with 1D nanotubes wrapped in 2D nanosheets structure (termed as 1D@2D ZnCo-HNC), via a one-step bio-inspired pyrolysis. The feeding ratio of Zn to Co precursor and pyrolytic temperature are critically modulated to achieve well-defined morphologies of the products, endowing them with the integrated merits of nanotubes and nanosheets as efficient ORR catalysts. Benefiting from the particular structure and electronic regulation of Zn on Co, the ZnCo-Nx dual-atomic system exhibits excellent ORR catalytic characteristics with an onset potential of 1.05V and a half-wave potential of 0.82V. Density functional theory calculations further explain the regulating role of Zn, such that the adjusted Co in ZnCo-Nx sites significantly reduces the energy cost to ultimately facilitate the ORR. Moreover, the Zn-air battery assembled with ZnCo-HNC is capable of delivering the maximum power density of 123.7mW cm-2 and robust stability for 110 h (330 cycles). This method provides a promising strategy for fabricating efficient transition metal-based carbon catalysts for green energy devices.

Apoplastic and symplastic zinc concentration of intact leaves of field onion (Allisum cepa) as affected by foliar application of ZnSO4 and Zn-amino chelates

A better understanding of the physiological mechanisms by which zinc (Zn) is absorbed by plant leaves may provide additional basic information to help in the improvement of Zn foliar application programs. In this two-year field experiment, apoplastic and symplastic distribution of Zn in the leaves and re-translocation from the leaves to the bulb of onion (Allisum cepa L. cv. Behbahan) as affected by foliar application of different Zn fertilizer sources was investigated. Four Zn fertilizer sources, i.e., ZnSO4 and Zn-lysine (Zn-Lys), Zn-methionine (Zn-Met), and Zn-threonine (Zn-Thr) were applied as foliar spray at a concentration of 0.5% Zn. Free amino acids (i.e., Lys, Met, and Thr) were used to separate the effect of Zn and accompanying amino acids. A free of Zn and amino acid treatment was also considered as control. The Zn-form revealed significant influence on apoplastic Zn concentration. Foliar application of Zn-amino chelates particularly Zn-Lys increased contribution of symplastic to apoplastic Zn in onion leaves by decreasing the Zn retention on the apoplastic spaces. Higher leaf symplastic Zn in the plants supplied with the Zn-Lys in comparison with those supplied with the other Zn fertilizer sources was accompanied with higher bulb Zn accumulation. This was probably due to larger re-translocation of Zn from the leaves to the bulb at the Zn-Lys treatment. Spraying Zn and amino acids either free or complexed with Zn produced an increase in Zn concentration provoking a decrease of nitrate concentration in the bulbs and the highest effect was observed at the Zn-Lys treatment. According to the results, Zn-Lys was more effective than ZnSO4 in enhancing the symplastic to apoplastic Zn ratio in the leaves and resulted higher accumulation of Zn in the bulbs.

Enhanced structural, optical, and photocatalytic activity of novel Cd–Zn co-doped Mg0.25 Fe1.75O4 for degradation of RhB dye under visible light irradiation

CdxZn1-xMg0.25Fe1.75O4 (where x = 0.00, 0.25, 0.50, 0.75, 1.00) have been successfully produced by a facile hydrothermal technique for a thorough comparison of structural, optical, and photocatalytic properties (degradation of Rhodamine B -RhB dye under visible light irradiation). X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) confirmed the formation of cubic spinel structure for all of the samples. Fourier transform infrared (FTIR) spectroscopy verified the presence of metal-oxygen (M–O) bonding in the prepared samples with two frequency bands corresponding to phonon vibrational stretching in both the octahedral and tetrahedral lattice positions. UV–Visible Spectrophotometer and photoluminescence (PL) spectroscopy investigated the bandgap variation (2.7 eV-1.7 eV) and emission spectrum peaks appearing in the range of 405–471 nm region. The comparison in the photo-degradation of Rhodamine B (RhB) revealed the superior performance (98% degradation of RhB dye in 80 min having a K value of 0.04966 with excellent reusability) of Cd0.50Zn0.50Mg0.25Fe1.75O4 sample having 50/50 dopant ratio of Cd and Zn in the parent Mg Ferrite, attributed to the lowest bandgap, longer lifetime of charge carriers, active octahedral lattice site, electron/hole pair recombination preventions, and the least value of ohmic impedance at higher frequency.

Syntheses and Characterizations of CuIn1-xZnxSe2 Chalcopyrite Nanoparticles.

CuIn1-xZnxSe2 powders with various atomic percentages (x = 0, 0.05, 0.11, 0.16 and 0.21) were synthesized with the solvothermal method using metal chlorides and ethylendiamine as sources of precursors and a solvent, respectively. The experiment aims to investigate the effect of atomic percentages of Znx compounds on the structural and optical properties of CuIn1-xZnxSe2 in order to improve future technological applications based on this material. The powders’ chalcopyrite phases were identified by X-ray diffraction. Energy dispersive X-ray spectroscopy analysis revealed the presence of Cu, In, Zn and Se with the expected atomic ratio of Zn/(In + Zn). Scanning electron microscopy and transmission electron microscopy analysis showed that the powders have large-scale desert rose-like structures. The nanopowders’ optical study by UV-visible spectrophotometry showed that the CuIn1-xZnxSe2 energy gap values increase with the molar fraction of Znx. A change from 1.15 to 1.4 eV was observed.

Evaluation of zinc, copper, and Cu:Zn ratio in serum, and their implications in the course of COVID-19

BackgroundThe dynamics of essential metals such as Copper (Cu) and Zinc (Zn) may be associated with the novel coronavirus disease 2019 (COVID-19) that has spread across the globe. ObjectivesThe aim of this study is to investigate the relationship between serum levels of Cu and Zn, as well as the Cu:Zn ratio in the acute phase of COVID-19 along with the assessment of their connection to other laboratory parameters (hematological, biochemical, hemostatic). MethodsSerum levels of Cu and Zn were measured by atomic absorption spectrometry in 75 patients in the acute COVID-19 phase and were compared with those of 22 COVID-19 patients evaluated three months after the acute phase of the disease (‘non-acute’ group) and with those of 68 healthy individuals. ResultsIn comparison with both the non-acute patients and the healthy controls, the acute patients had lower levels of hemoglobulin and albumin, and higher levels of glucose, creatinine, liver transaminases, C-reactive protein (CRP), and higher values of the neutrophils to lymphocytes ratio (NLR) at the hospital admission. They also exhibited increased levels of Cu and decreased of Zn, well represented by the Cu:Zn ratio which was higher in the acute patients than in both non-acute patients (p = 0.001) and healthy controls (p < 0.001), with no statistical difference between the last two groups. The Cu:Zn ratio (log scale) positively correlated with CRP (log scale; r = 0.581, p < 0.001) and NLR (r = 0.436, p = 0.003). ConclusionCurrent results demonstrate that abnormal dynamics of Cu and Zn levels in serum occur early during the course of COVID-19 disease, and are mainly associated with the inflammation response.

Biosynthesis of Zinc Oxide (ZnO) Using the Biomass of Aspergillus niger to Impart Cotton Fabric with Antimicrobial Properties

AbstractThe biosynthesis of ZnO is performed through enzymatic mechanisms for controlling the particle size and morphology with using the sol‐gel method. Furthermore, this method utilizes a stabilizer obtained from the cell biomass of Aspergillus niger mold in order to yield homogeneous and consistent products. The evaluation of functional, morphological, and antibacterial activities was carried out at pH 6.0‐13.0. The analysis FT‐IR showed the interaction of hydroxyl groups, aromatic rings, as well as N−H and O−Zn‐O compounds at a wavenumber of 401–584 cm−1. The XRD and SEM characterizations showed that ZnO structure and crystal phase were hexagonal wurtzite at dimensions of 36.2 ‐ 45.4 nm. The differences in pH also influenced the dimensions, morphology, and antimicrobial activity. ZnO with a pH of 8.0 was characterized by FESEM‐EDAX, based on the analysis of morphological uniformity. This characterization obtained rod and cube structures, with atomic ratios of Zn=61.5 % and O=38.5 %. The UV‐DRS spectrum showed that the optical band gap with a value of Eg=3.00–3.11 eV. The differences in morphology further distinguished antibacterial properties on textile fibers, through the use of the Gram ‐ and + bacteria (Pseudomonas aeruginosa and Staphylococcus aureus), with inhibition zones of 17–21 mm and 21–25 mm, respectively. Therefore, ZnO is classified as a very strong antibacterial material than amoxicillin, with an inhibition zone of 13.6 mm.

CMOS Compatible Al‐Doped ZnO Sol–Gel Thin‐Film Properties

Zinc oxide (ZnO) is a low‐cost class of n‐type inorganic semiconductors with a large exciton binding energy (≈60 meV), wide direct bandgap (3.37 eV), and the most important material for various fields of industrial and deep‐tech applications. Herein, a complementary metal–oxide–semiconductor (CMOS) temperature compatible (400 °C)‐ integrated circuit (IC) process based on the sol–gel method is described. The properties of aluminum (Al)‐doped ZnO (AZO) thin films were investigated. The Al content, Al/(Al+Zn) ratio, varies from 0 to 10% and exhibits compressive stresses from −4 to −1.8 GPa. At low dopant concentrations, the Al content acts as an electrical dopant, while at higher dopant concentrations, it acts as an impurity. The electrical resistivity, which was only 3 × 10−3 Ω cm, is inversely related to the orientation of the thin film, which was preferably along the (0 0 2) direction. The optical bandgap energy of AZO thin films was determined to be in the range of 3.34–3.87 eV. Herein, a novel method to change the Al content of doped AZO thin films to improve their properties is described, which is suitable for next‐generation flexible, microsystem, and optoelectronic devices.

Phytoaccumulation of Heavy Metals by Sodom Apple (Calotropis procera (Aiton) W. T. Aiton) along an Urban–Rural Gradient

Heavy metals (HMs) are widely recognized for their toxicity and have serious environmental implications as technology advances and public pressure mounts to guarantee the safest and healthiest environment. This study evaluates the phytoremediation potential of HMs i.e., Copper (Cu), Zinc (Zn), Lead (Pb), and Cadmium (Cd) by Calotropis procera (Aiton) W.T. Aiton, also known as Sodom apple, along an urban–rural gradient and its effect on communities’ diversity, forage and medicinal quality in semi-arid region of Khyber Pakhtunkhwa Pakistan. The HM concentration was investigated along with the urban–rural gradients by sampling C. procera and soil samples. Acid-digested samples were tested for metal concentration using an atomic absorption spectrophotometer (AAS). We used principal component analysis and cluster analysis to identify the pattern of metal distribution in plants and soil. To comprehend the species’ diversity of plant communities in polluted sites, the species’ composition of C. procera communities was explored. Our results showed that the concentration of HMs in the soil and plant decreased from Zn to Cd (Zn &gt; Cu &gt; Pb &gt; Cd). Likewise, more than half of the soil metal accumulated in the roots and aerial part of the plant, indicating the bioaccumulation potential of the plant species for these metals. Zn, Cu, Pb, and Cd translocation ratio varied from root &gt; stem &gt; leaf &gt; flower. Root to stem transfer of metal was poor, but strongly mobilized to the leaves when available in the stems. Carthamus lanatus, Sonchus asper, Cynodon dactylon, Xanthium strumarium, and Silybum marianum were the leading species in three groups of 36 plant species. Pearson’s correlation revealed a significant relationship between HM concentrations and diversity indices. Zn and Cu content in the soil influenced plant species richness, Shannon–Wiener index (H′), and evenness index (Eh). Given the environmental toxicity of HMs, Cd concentrations in soil exceeded the permissible level, suggesting residents should be warned about potential health risks. As a result, the species chosen for this study can be employed as a biomonitor and phytoremediator of soil contaminated by these HMs, as it can accumulate HMs to a toxic level.

Geology and pyrite-polymetallic mineralization of the forecasted&#x0D; Limonite deposit, Rassokhinsky ore cluster (Yenisei ridge)

The development of Russia’s largest Gorevskoye leadzinc&#x0D; deposit (Gorevsky GOK, Novoangarsky OK) will&#x0D; depend on promising deposits of the Angara polymetallic&#x0D; ore region, in particular, those of the Rassokhinsky&#x0D; ore cluster. Based on the analysis of geological and geophysical&#x0D; information of previous and current studies,&#x0D; a major Limonite pyrite-polymetallic (massive sulfide)&#x0D; deposit is forecasted within it. The main lithological&#x0D; and stratigraphic criterion for the localization of ores is&#x0D; determined by their confinement to high-carbon black&#x0D; quartz-sericite schists of the upper subformation of the&#x0D; Potoskuy suite of the Upper Riphean. In the top of this&#x0D; pack, layered and massive pyrite-polymetallic ores, 70–&#x0D; 140 m thick, are localized. Based on PPA data, lead and&#x0D; zinc content in core varies from fractions of a percent&#x0D; to several percent, based on the ICP-AES method: 0,1–&#x0D; 3,7 % Pb, 0,1–6,4 % Zn, Pb : Zn ratio is 1 : (1–10).

Microwave-assisted rapid synthesis of Cu2S:ZnIn2S4 marigold-like nanoflower heterojunctions and enhanced visible light photocatalytic hydrogen production via Pt sensitization

In this work, a rapid microwave synthesis route is presented for the fabrication of morphology-controlled Cu2S: ZnIn2S4 marigold-like nanoflower heterojunction photocatalysts. The Cu-to-Zn-metal -cation (Cu:Zn) ratios were used to control the Cu2S: ZnIn2S4 heterojunction during the second step of microwave synthesis. The formation of Cu2S: ZnIn2S4 heterojunction is evidenced by XRD, TEM and XPS analyses. The optimum electronic interaction aids to stimulate electron-hole charge separation kinetics and promote the solar hydrogen (H2) evolution performance in microwave-assisted 5 mol.% Cu2S:ZnIn2S4 (Cu2S:ZIS–5) heterojunction. Benefiting from the synergy between marigold-like morphology, heterojunction, and Pt loading, the optimum Pt loaded Cu2S: ZIS–5 marigold nanoflowers (Pt/Cu2S:ZIS–5) exhibited the 862 µmol of photocatalytic H2 production after 3 h under visible light irradiation (≥420 nm). The time-resolved PL spectrum showed more than double carrier lifetime in Pt/Cu2S: ZIS–5 heterojunction (45 ns) than that of Pt/ZIS–15 (20 ns). These visible light-responsive Pt/Cu2S:ZIS marigold-like nanoflower heterojunction shows promising photostability, which would open new opportunities for the development of highly efficient ternary metal-chalcogenide photocatalysts for solar hydrogen generation.

Facile Fabrication of ZnO-ZnFe2O4 Hollow Nanostructure by a One-Needle Syringe Electrospinning Method for a High-Selective H2S Gas Sensor.

Herein, a facile fabrication process of ZnO-ZnFe2O4 hollow nanofibers through one-needle syringe electrospinning and the following calcination process is presented. The various compositions of the ZnO-ZnFe2O4 nanofibers are simply created by controlling the metal precursor ratios of Zn and Fe. Moreover, the different diffusion rates of the metal oxides and metal precursors generate a hollow nanostructure during calcination. The hollow structure of the ZnO-ZnFe2O4 enables an enlarged surface area and increased gas sensing sites. In addition, the interface of ZnO and ZnFe2O4 forms a p-n junction to improve gas response and to lower operation temperature. The optimized ZnO-ZnFe2O4 has shown good H2S gas sensing properties of 84.5 (S = Ra/Rg) at 10 ppm at 250 °C with excellent selectivity. This study shows the good potential of p-n junction ZnO-ZnFe2O4 on H2S detection and affords a promising sensor design for a high-performance gas sensor.

Gradient Co/Zn bimetallic coordinated polymer-derived hierarchically porous carbon for boosted oxygen electrocatalysts of rechargeable Zn–air batteries

The controllable design of low-cost oxygen electrocatalysts with outstanding activity and durability is a top priority for rechargeable metal–air batteries. Herein, a facile approach is proposed for obtaining hierarchically porous cobalt–nitrogen codoped carbon for reversible oxygen reduction and evolution reactions via the pyrolysis of Co/Zn bimetallic coordinated polymers with gradient Co:Zn ratio. The evaporation of Zn species during the pyrolysis process combined with the Kirkendall effect of Co species resulted in the formation of hierarchical porosity, which further creates highly accessible defective sites and improves multiscale mass transfer. The C-7Co93Zn catalyst with optimized defective Co–Nx and small-sized Co3O4 nanoparticles delivers an optimal bifunctional activity with a potential gap of 0.79 V for reversible oxygen reduction reaction (E1/2) and oxygen evolution reaction (Ej = 10). Moreover, it displays a superior power density of 122 mW cm−2 and long-term durability in a rechargeable Zn–air battery. Density functional theory calculations indicate that the defects adjacent to Co–Nx display improved electrocatalytic oxygen reduction with a smaller energy barrier. This work provides a facile method for optimizing the Co:Zn ratio towards the synthesis of bifunctional oxygen electrocatalyst derived from a class of bimetallic coordinated polymers resulting in hierarchically porous structure and defective cobalt-based active sites.

Facile synthesis of ZnMoO4/AlPO4-5 nanorod composites as visible-light-driven photocatalysts and high-performance energy storage materials.

The present article describes the facile one-step hydrothermal synthesis of single-crystalline ZnMoO4/AlPO4-5 nanorod composites. The physicochemical properties of the synthesized materials, such as structure, morphology, and bandgap, were determined using techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), N2 adsorption–desorption isotherms, X-ray photoelectron (XPS), ultraviolet-visible (UV-vis), and photoluminescence (PL). The XRD pattern of synthesized ZnMoO4/AlPO4-5 verifies the synthesis of nanocomposites. Diffuse UV-vis spectra reveal that ZnMoO4/AlPO4-5 nanorod composites exhibit an indirect semiconductor with an optical bandgap between 3.15 and 3.7 eV depending on Mo : Zn ratio. In comparison to pure AlPO4-5, ZnMoO4/AlPO4-5 nanocrystal composites showed significantly higher photocatalytic activity for the degradation of para-nitrophenol (PNP, 0.04 g l−1), with 14, 99, 70, and 54% for AlPO4-5, Mo : Zn (2)/AlPO4-5, Mo : Zn (4)/AlPO4-5, and Mo : Zn (6)/AlPO4-5, respectively. This result might be attributed to the composite's efficient charge transfer and optimized electron–hole pair recombination. The supercapacitive ability of ZnMoO4/AlPO4-5 nanorod composites was also investigated in this work. For the prepared electrodes using AlPO4-5, Mo : Zn (2)/AlPO4-5, Mo : Zn (4)/AlPO4-5, and Mo : Zn (6)/AlPO4-5, the capacitance values were 400, 725, 450, and 481.25 F g−1, respectively, at a current density of 0.5 A g−1. This study shows that ZnMoO4/AlPO4-5 nanorod composites are a potential visible-light-responsive photocatalyst. The electrochemical results further demonstrate the high capacitance of ZnMoO4/AlPO4-5 nanorod composites toward energy-storage applications.

Finite element analysis on effect of aspect ratio and specimen geometry of biodegradable Zn 0.2 Ti 1 Mg / HA-WA composite for biomedical applications

In the present study, numerical simulations are employed to evaluate elastic properties of hydroxyapatite and wollastonite reinforced Zinc alloy biocomposite with finite element approach. Prior insight for experimental procedures on compressive behaviour of implant is established with prime focus on effect of aspect ratio. Aspect ratio has a prominent effect in load transfer along the length of the specimen. The parametric study conducted to evaluate the effect of aspect ratio on the geometry of compressive specimen and strain on the composite reveals phenomenal variations. The results of the analysis exhibits square specimen has lower stresses, hence use of square specimen is insignificant in compression experiments. Both square and circular specimens averages the stresses at an aspect ratio of 1.7 which indicates the optimum aspect ratio for compression experimentation. The findings of the this numerical analysis can guide experimentation in making better decisions on specimen geometry, aspect ratio and strain to evaluate the compressive behaviour.

Geodynamic conditions of massive sulfide formation in the Magnitogorsk megazone

Research subject. Volcanism, rock geochemistry, geodynamics, and massive sulfide formation in the Magnitogorsk megazone (MMZ) of the Southern Urals in the Middle Paleozoic.Materials and Methods. Across the largest part of the massive sulfide deposits under investigation, the authors conducted route studies, including geological surveys of individual ore fields and quarries of deposits, core samples of deep wells and transparent sections. Representative analyses of petrogenic and microelements were performed using wet chemistry and ICP-MS in analytical centers in Russia and Europe. Along with the authors’ data, analytical materials published by Russian and foreign researchers were used. Geodynamic reconstructions were carried out taking into account regional data on gravics, thermal field, magnetometry, and seismic stu dies, including «Urseis-95».Results. The geodynamic reconstructions established that the main elements of the paleostructure of the Southern Urals in the Devonian were the subduction zone of the eastern dip and asthenospheric diapirs that penetrated into the «slab-window», which determined the type of volcanic belts, the composition and volume of volcanic rocks of pyrite-bearing complexes, and ore matter of pyrite deposits. The following geodynamic zones in the MMZ were identified: 1 – polychronous accretion prism; 2 – frontal and developed island arcs (D1e2–D2ef1); 3 – zone of back-arc spreading (D1e2); 4 – rear island arc (D2ef1).Conclusions. All investigated zones and ore areas are characterized by an autonomous development of volcanism, a special deep structure and a different composition, as well as by a different volume of massive sulfide deposits that vary in the Cu and Zn ratios and Pb, Ba, Au amounts. In the MMZ volcanic complexes, three groups of plume source basalts are distinguished. The results can be used in predictive-estimation and search operations for massive sulfide mineralization.

Morphology and I-V Characteristics of Electrochemically Deposited Zinc Oxide on Silicon

This paper reported on the electrochemical deposition of zinc oxide (ZnO) on p-silicon (p-Si) (100) substrate in the mixture of 0.1 M of zinc chloride (ZnCl2) and potassium chloride (KCl) electrolyte at a volume ratio of 1:1, 3:1 and 5:1 namely Sample A, B and C. The deposition process was done in room temperature with a current density of 10 mA/cm2 for 30 minutes. Prior to the experiment, all samples were treated by RCA cleaning steps. All samples were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The results show that all samples have the same morphology of a flake-like structure with different Zn:O ratio that were 2.81, 2.35 and 2.49 for samples A, B and C. The current-voltage (I-V) characteristic graph was obtained by dark current measurement using Keithley SMU 2400 and the threshold voltage (Vth) values were determined at 2.21 V, 0.85 V and 1.22 V for sample A, B and C respectively which correspond with the Zn:O ratio where the highest value of Zn:O ratio can be found in sample A and the lowest in sample B. Based on these results, it shows that electrochemical deposition technique is capable of being used to deposit the flake-like structure ZnO on semiconductor material to form the p-n junction which behaves like a diode. The value of Vth seems to be depended on the ratio between Zn and O. Higher ratio of Zn and O will cause the higher value of intrinsic carrier concentration and built in potential which will increase the Vth value.

Highly Enhanced Catalytic Stability of Copper by the Synergistic Effect of Porous Hierarchy and Alloying for Selective Hydrogenation Reaction

Supported copper has a great potential for replacing the commercial palladium-based catalysts in the field of selective alkynes/alkadienes hydrogenation due to its excellent alkene selectivity and relatively high activity. However, fatally, it has a low catalytic stability owing to the rapid oligomerization of alkenes on the copper surface. In this study, 2.5 wt% Cu catalysts with various Cu:Zn ratios and supported on hierarchically porous alumina (HA) were designed and synthesized by deposition–precipitation with urea. Macropores (with diameters of 1 μm) and mesopores (with diameters of 3.5 nm) were introduced by the hydrolysis of metal alkoxides. After in situ activation at 350 °C, the catalytic stability of Cu was highly enhanced, with a limited effect on the catalytic activity and alkene selectivity. The time needed for losing 10% butadiene conversion for Cu1Zn3/HA was ~40 h, which is 20 times higher than that found for Cu/HA (~2 h), and 160 times higher than that found for Cu/bulky alumina (0.25 h). It was found that this type of enhancement in catalytic stability was mainly due to the rapid mass transportation in hierarchically porous structure (i.e., four times higher than that in bulky commercial alumina) and the well-dispersed copper active site modified by Zn, with identification by STEM–HAADF coupled with EDX. This study offers a universal way to optimize the catalytic stability of selective hydrogenation reactions.

Evaluation of Zn‐substituted La0.5Sr0.5CoO3 ceramics as functional materials for thick‐film resistors

AbstractThis work focuses on the evaluation of La0.5Sr0.5Co1‐xZnxO3 (LSCZ, x = 0.00–0.10) ceramics as an air‐fireable and economical functional material for thick film resistors. Solid‐state reaction experiments and first‐principles calculations were conducted to investigate the crystal structure, thermal behaviors, and electrical properties of LSCZ ceramics. The substitution of Zn2+ modified the bond properties, electron distribution, and band structure, resulting in more serious structural deformation, increasing the bond population of Co–O and weakening the charge transfer of LSCZ. Experimental results showed that the addition of Zn2+ lowered the densification temperature, activation energy, and crystallite size. As the ratio of Zn2+ increased, the conductivity and temperature coefficient of resistance showed a downward trend. Impedance variation with frequency and thermal aging tests were also performed. For the x = 0.05 specimen sintered at 1200°C, values of 95.5% for relative density, 2857 S/cm for conductivity, 1267 ppm/°C for temperature coefficient of resistance, –0.47% for conductivity change could be achieved.