Increase In Sulfur Content Research Articles

Roles of Sulfur Sources in the Formation of Alloyed Cu2–xSySe1–y Nanocrystals: Controllable Synthesis and Tuning of Plasmonic Resonance Absorption

Ternary alloyed Cu2–xSySe1–y nanocrystals (NCs) were synthesized by using a simple and phosphine-free colloidal approach, in which sulfur powder and 1-dodecanethiol (DDT) were used as sulfur sources. In both cases, the crystal phase transformed from cubic berzelianite to monoclinic djurleite structure together with the morphology evolution from quasi-triangular to spherical or discal with an increase of sulfur content. Accordingly, the near-infrared (NIR) localized surface plasmon resonance (LSPR) absorption of the as-obtained sulfur-rich NCs exhibited obvious red-shift of wavelength and widening of absorption width. When the sulfur powder was chosen as sulfur sources, the LSPR wavelength of the as-obtained alloyed Cu2–xSySe1–y NCs could be tuned from 975 to 1230 nm with a decrease of selenium content in the NCs. In contrast, the region of the red-shift could be up to 1250 nm for the alloyed NCs synthesized by incorporation of different DDT dosage into the reaction system. The different sulfur sources and the electron donating effects of the DDT as a ligand played an important role in the LSPR absorption tuning. This deduction could be testified by the post-treating the quasi-triangular Cu2–xSe NCs with DDT under different temperatures and over different reaction time, which exhibited a red-shift of LSPR wavelength up to 450 nm due to coordination of DDT to Cu atoms on the NC surface while incorporating some sulfur anions into the lattice. This study offers a convenient tool for tuning the LSPR absorption of copper chalcogenide NCs and makes them for application in biological and optoelectronic fields.

Optimization of Co-Injection Desulfurization of Vanadium Bearing Hot Metal

The desulphurization process parameters of vanadium bearing hot metal were optimized. It is found that it has the best desulfurization effect in 100t hot metal ladle, when the lance position is 280mm, the ratio of lime to Mg is 3:1, and the Mg injection rate is 9kg/min. The Si and Ti content of hot metal can increase the activity of S. With the increase of Si and Ti content of hot metal, the final sulfur content has a reduction trend. When the content of Si and Ti is lower than 0.35%, the final sulfur content of hot metal increases, and the hit rate decreases. The effect of hot metal temperature on desulfurization end point hit rate is obvious. When the hot metal temperature is between 1300~1320°C, the hit rate of desulfurization end point is higher. When the temperature is below 1300°C or above 1320°C, the sulfur content increases. After optimization of process parameters, the Mg and lime consumption per ton of hot iron are reduced by 0.11kg and 0.54kg, respectively, with the average hit rate of desulfurization end point increased by 22.6% and 10.7%, respectively.

Combustion of Hydrogen Sulfide-Containing Oil on the Surface of the Water and Possible Applications of Combustion Method at Sea

Oil production in sea conditions is associated with certain difficulties of the field development process due to technological peculiarities of oil production at sea. The Caspian Sea is an enclosed pond with a very sensitive ecosystem, therefore, maritime operations here meet higher requirements than in open ponds. The uniqueness of the Caspian Sea is in the fact that its biological wealth has no analogues in the world, therefore, mining without complying with strict ecological requirements can cause irreparable harm to the environment. This work deals with the analysis of the possibility to use controlled combustion in situ in case of accidents on the Kashagan oil field which is located in the Caspian Sea. The Kashagan oil field is distinguished by a high content of hydrogen sulphide. In order to study the operational possibilities of oil combustion in situ, the process of evaporation and combustion of desulfurized oil from the Kashagan field depending on salinity of water was studied in this work. The process of evaporation of hydrogen sulphide from hydrogen sulphide-containing oil and the peculiarities of its combustion on water surface were studied in this work. It has been stated that the main difference in oil combustion with a high content of hydrogen sulphide is that the oil combustion process leads to the increase of sulfur concentration in oil residue after combustion.

Phase relations and structure–properties correlations in Fe(S,Se,Te)

Three series of polycrystalline samples with nominal compositions Fe1.02TeySe1−y−xSx (y = 0.3, 0.4, 0.6 and 0≤x≤0.7) have been synthesized and studied by means of the X-ray diffraction, scanning electron microscopy, electrical resistivity and magnetization measurements. Together with the tetragonal superconducting phase, all the samples have been found to contain a hexagonal phase of the NiAs-type; and the increase in sulfur content leads to a redistribution of various chalcogens between phases due to the difference in solubility limits and variations of the chemical compositions and volume fractions of these phases. The sulfur for selenium substitution in Fe1.02TeySe1−y−xSx results in a growth in the average interlayer distance in the superconducting tetragonal phase because of its enrichment by tellurium and depletion in sulfur; while the hexagonal phase becomes enriched by sulfur and depleted in tellurium with increasing sulfur content in the samples. It has been shown that in the Fe(Te,Se,S) materials with ternary mixture of chalcogens, the variation of the critical superconducting temperature correlates with the change in the average interlayer distance in the tetragonal structure as in other FeSe-based materials.

Mass Transfer Model of Desulfurization in the Electroslag Remelting Process

Experimental and theoretical studies have been carried out to investigate the effects of the slag on desulfurization during the electroslag remelting (ESR) process with a focus of developing a mass transfer model to understand the mechanism of desulfurization. Stainless steel 1Cr21Ni5Ti was used as the electrode and remelted with two different kinds of slags using a 50-kg ESR furnace. The contents of sulfur along the axial direction of product ingots were analyzed. It was found that the sulfur content of 350 ppm in the electrode is reduced to 71 to 95 ppm in the ingot by remelting with the slag containing 5 wt pct of CaO, and lowered more to 47 to 59 ppm with another slag having 20 wt pct CaO. On the basis of the penetration and film theories, the theoretical model developed in this work well elucidates the kinetics of desulfurization revealing the mechanism of sulfur transfer during the ESR process. The calculation results obtained from the model agree well with the experimental results. The model indicates that when sulfur content in electrode is given, there is a corresponding minimum value of sulfur content in the ingot due to the kinetics limit. This lowest sulfur content cannot be further reduced even with increasing L S (sulfur distribution coefficient between metal and slag phases) or decreasing sulfur content in the slag. Constant addition of extra amount of CaO to the molten slag with the increase of sulfur content in the slag during the remelting process can improve the macrosegregation of sulfur distributed along the axial direction of ESR ingots. Since the rate-determining steps of the sulfur mass transfer lie in the metal phase, adding calcium as deoxidizer can change mass transfer of sulfur and thus promote desulfurization further during the ESR process.

Norbornylized soybean oil as a sustainable new plasticizer for rubbers with hybrid fillers

AbstractCarbon black (CB) and precipitated silica are two major reinforcing fillers in rubbers. CB/silica hybrid filler is also widely used in rubbers to provide balanced properties. CB/silica‐hybrid‐filler‐filled styrene‐butadiene rubber (SBR) containing naphthenic oil (NO), soybean oil (SO) and norbornylized SO (NSO) was investigated. The swelling and curing behavior and rheological, mechanical, thermal, aging and dynamic properties were studied and compared with earlier reported data on CB‐ or silica‐filled SBR. NSO provides better scorch safety and faster cure than SO. Compared with NO, the addition of SO and NSO enhances the thermal stability and aging resistance of SBR vulcanizates. SBR/NSO vulcanizates with hybrid filler exhibit a higher tensile and tear strength than SBR/NO and SBR/SO vulcanizates. A synergistic effect in the abrasion resistance of vulcanizates containing the hybrid filler is observed. An increase of sulfur content in the hybrid‐filler‐filled SBR/NSO vulcanizates provides further improvement in abrasion resistance, wet traction and rolling resistance. © 2017 Society of Chemical Industry

Polythene Mulch and Irrigation for Mitigation of Salinity Effects on Maize (<i>Zea mays</i> L.)

A pot experiment was conducted at the net house of Patuakhali Science and Technology University during rabi season 2014-15 to estimate the contribution of polythene mulch and irrigation on reducing of salinity effect on maize (Zea mays L.). The experiment was laid out in a three factors randomized complete block design with three replications. The factors were salinity (two levels: without and 5 dS/m salinity), mulch (two levels: without and with polythene mulch) and irrigation (three levels: 125, 250 and 500 ml water/irrigation). BARI hybrid maize-7 was the test crop. Every pot received the same amount of fertilizer nutrients. Crops were harvested at tassel initiation stage. Mulch increased soil temperature by 2 to 4.5°C (with average of 3.1°C) over without mulch. In without mulch condition, salinity reduced shoot fresh and dry, and root fresh and dry weight by 28.3, 10.3, 39.4 and 30.6%, respectively. In with mulch condition, however, these reductions were 1.0, 7.2, 12.3 and 12.1 %, respectively. Polythene mulch reduced salinity induced reduction of the above parameters by 96.5, 30.1, 68.8 and 60.5 %, respectively. Under 125, 250 and 500 ml water/irrigation treatment, salinity reduced shoot fresh weight by 14.2, 19.3 and 6.7 %, respectively; shoot dry weight by 15.4, 6.6 and 5.0 %, respectively; and root fresh weight by 27.5, 20 and 11.6 %, respectively. Thus, the effect of salinity in maize was gradually decreased with the increasing amounts of irrigation water. Soil salinity reduced phosphorus and increased sulphur content in maize plants.The Agriculturists 2016; 14(2) 01-13

Effect of sulphur concentration on the structural and electronic properties of ZnS nanoparticles synthesized using chemical precipitation method

A systematic study is presented on the synthesis of ZnS nanoparticles by using simple chemical precipitation method without using any capping agent. The ZnS nanoparticles have been synthesized using precursor solution with different Zn2+:S2− ratio. The as synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–Vis absorption spectroscopy and impedance spectroscopy. The XRD patterns reveal the formation of ZnS nanoparticles with wurtzite hexagonal phase which changes to sphalarite phase for higher concentration of S2− in the precursor solution. XRD, SEM and AFM studies have shown enhancement in particle size on increasing sulphur content. SEM and AFM images depict formation of deformed spherical nanoparticles with particle size ranging from 10 to 50 nm. Optical absorption spectra of synthesized material show a red shift in the optical absorption on increase of S2− ion concentration. Variation in electrical conductivity obtained from impedance measurements at different temperatures has been suitably correlated to Davis–Mott model.

EFFECT OF SMALL BULK SULFUR CONTENT AND ANNEALING TEMPERATURE ON THE INTERGRANULAR FRACTURING SUSCEPTIBILITY OF METALLIC NICKEL

In this paper, we investigate the influence of temperature on the nickel grain boundary equilibrium segregation of sulfur and the resulting intergranular fracturing susceptibility. Auger electron spectroscopy has been used to study equilibrium segregation of sulfur to the grain boundaries of a metallic nickel, with a mass bulk content of 3.6[Formula: see text]ppm in sulfur. Samples were first annealed at adequate temperatures for sufficiently large equilibrium time, and then quenched in water at room temperature. The analysis carried out shows a significant increase of sulfur concentration in the grain boundary with decreasing temperature. However, the sulfur content in the grain boundary shows a drastic shrink at 700[Formula: see text]C. This can be interpreted by the formation of an aggregate sulfide compound in the area of the grain boundaries. At 650[Formula: see text]C, in situ brittle fracture becomes unworkable and only intragranular fractures are observed. Using the results obtained through the investigation of the grain boundaries by Auger spectroscopy, the standard segregation energy is estimated as [Formula: see text].

Effect of Sulfur Evaporation Rate on Screw Dislocation Driven Growth of MoS2 with High Atomic Step Density

We report the sulfur evaporation rate controlled screw dislocation driven growth of two-dimensional MoS2 that contains unprecedented atomic step density. Screw dislocation assisted growth of atomic thin MoS2 on amorphous SiO2 or a crystalline and conducting Si substrate paves the way to form spiral morphology of two-dimensional materials without the need for single crystalline miscut substrates to initiate the line defects. The unique spiral morphology promoted by screw dislocation is typically observed at a high nucleation rate induced by an abrupt increase in sulfur concentration. Screw dislocation assisted spiral MoS2 growth leads to a high step density with an ∼5 fold increase in the total edge length. Statistical analysis from detailed atomic force microscope phase imaging of flat and spiral MoS2 flakes reveals the linear increase in total edge length from ∼470 nm to ∼2325 nm with respect to variation in the number of steps available at the spiral structure in the range of 2–8. High resolution transm...

Possible Paths of Origin of Gas-Oil Systems and Causes of Differences in Their Properties

A sequence of possible reactions occurring during evolution of deep-lying fluids, components of which could be sources of biogenous oil substances, is studied within the confines of biogenetic concept of formation of oil. Oxidative condensation transformation of methane and its immediate homologs under the action of sulfur present in some fluids might have facilitated formation of various types of hydrocarbons and organosulfur compounds. The possibility of such transformations is supported by the stable direct correlations between sulfur concentration in oils, their density, viscosity, content of asphaltic-resinous components and heavy fractions, and the scale of oil deposits. The proportion of gas in the oil-gas systems decreases with increase of sulfur content. Metals, like V and Ni, in the deep-lying fluids affect the geochemical type of oil. Vanadium oils are heavier (V > Ni), have high sulfur contents, and occur closer to the surface, while Ni oils are lighter (Ni < V), have low sulfur contents, and occur in deeper strata. These characteristics apparently stem from the different nature of catalytic properties of the metals and the structures containing them. Transformations of the oil fluid with the involvement of heterocomponents thus affect the fractional and chemical composition of oil-gas systems.

Optical and electrical properties of In4Se96-xSx chalcogenide thin films

The objective is to study the physical, structural, compositional, electrical and optical changes in InSeS alloy. In4Se96-xSx (where x = 0, 4, 8, 12) chalcogenide semiconductors has been deposited on non-conducting glass substrate by thermal evaporation technique at a pressure of approximately 10−6 Torr. The thin films were characterized by XRD, SEM, UV spectroscopy and electrical measurement. XRD shows the amorphous nature of the prepared thins films. Surface morphological analysis were carried out by scanning electron microscope (SEM), which shows the grain development of the prepared samples. Energy dispersive analysis by X-ray (EDAX) was used to check the compositional elements of deposited films. The analysis of the absorption spectra show indirect band gap, the magnitude of optical band gap increases and the corresponding absorption coefficient decreases with Sulfur concentration. The temperature dependent DC Conductivity (σdc) decreases and the corresponding activation energy increases with increase of Sulfur content for the In4Se96-xSx. High field conduction study shows the space charge limited conduction (SCLC) is dominated from where the density of states has been evaluated, density of state decreases with increases of sulfur concentration which may be due to decrease in disorderness or decrease in defects states of the system.

The effect of additional sulfur on solution-processed pure sulfide Cu2ZnSnS4 solar cell absorber layers

ABSTRACTTo reduce the amount of chalcogen needed in the post-annealing process, we demonstrate significantly increased sulfur incorporation into pure sulfide CZTS films achieved by increasing the thiourea content of DMSO-based precursor solution. The increase of sulfur content was confirmed by thermogravimetric analyses (TGA). To understand how the elemental distribution across the CZTS layer is affected by extra thiourea, a systematic compositional study was carried out using X-ray photoelectron spectroscopy (XPS). XPS depth profiling reveals increased sulfur incorporation in the final CZTS films when more thiourea is added to the solution. The grain size was reduced slightly with increased sulfur content and the surface morphology was changed significantly. The effect on the surface of the CZTS film has been investigated using scanning electron microscopy (SEM), Raman spectroscopy, and XPS. External-quantum-efficiency (EQE) measurements with an electrolyte contact were used to investigate the optoelectronic properties of the deposited CZTS films.

Influence of precursor molar concentration on the electrical and magnetic properties of synthesized MnS nanocrystals

MnS Nanocrystals have been synthesized with 1:1, 1:2 and 2:1 molar ratio of precursors using wet chemical method. The electrical and magnetic properties of as-synthesized MnS nanocrystals have been investigated using the impedance spectroscopy and vibrating sample magnetometer respectively. An increase in dielectric constant from 68.5 to 87.9 with increasing Mn content and decrease to 54.1 with increase in the sulfur content was observed. Both the dielectric constant and the loss factor increased with temperature due to the Maxwell–Wagner type interfacial space-charge polarization. The Cole–Cole plot confirmed that the conduction in as-synthesized samples are through the grain and grain boundaries. The resistance and capacitance of grain and grain boundaries have been calculated. The grain resistance varies from 248 to 199 Ω whereas the grain boundary resistance varies from 16 to 6.7 KΩ over the temperature ranges of 323–473 K for 1:1 sample. It endorsed the NTCR type behavior in all the samples. The electric modulus representation revealed the well-defined relaxation peaks. The relaxation time versus temperature behavior revealed that the relaxation time decreases with increase in temperature. AC-conductivity (σac) increases with increasing frequency and temperature. σac increases from 1.58 × 10−5 to 1.51 × 10−3 S cm−1 with the increase of Mn content and then decreases to 1.22 × 10−8 S cm−1 with increase of sulfur content. The activation energy is found to be 0.35 eV (1:1), 0.64 eV (1:2) and 0.28 eV (2:1) at 3 kHz. The chemically modified MnS nanocrystals exhibit paramagnetic behavior. A typical saturation magnetization of 0.56, 0.38, and 0.57 emu/g and coercivity of 2.31, 8.42, and 5.57 Oe at room temperature for 1:1, 1:2 and 2:1 sample respectively.

Ellipsometric study of optical properties of GaSxSe1-x layered mixed crystals

Spectroscopic ellipsometry measurements were performed on GaSxSe1-x mixed crystals (0⩽x⩽1) in the 1.2–6.2eV range. Spectral dependence of optical parameters; real and imaginary components of pseudodielectric function, pseudorefractive index and pseudoextinction coefficient were reported in the present work. Critical point (CP) analyses on second-energy derivative spectra of the pseudodielectric function were accomplished to find the interband transition energies. The revealed energy values were associated with each other taking into account the fact that band gap energy of mixed crystals rises with increase in sulfur content. The variation of CP energies with composition (x) was also plotted. Peaks in the spectra of studied optical parameters and CP energy values were observed to be shifted to higher energy values as sulfur concentration is increased in the mixed crystals.

Influence of Sulfur Species on Current Efficiency in the Aluminum Smelting Process

Anode impurities are the major source of sulfur in aluminum electrolysis. Sulfur in anodes is mainly found as organic compounds. Alumina also introduces small quantities of sulfur, typically in the form of sulfates. The scarcity and cost of low-sulfur raw materials and the possibility of sulfur removal from the cell by means of flue gas may make high-sulfur content anodes a viable option. However, some anode impurities are known to affect current efficiency in aluminum production and caution must be exercised. The effect of increased sulfur content in the aluminum electrolysis electrolyte must be studied. This paper explores the effect of increased sulfur concentration in the electrolyte on current efficiency in a laboratory cell. Sodium sulfate was added to the electrolyte as a source of sulfur at regular time intervals to maintain a constant sulfur concentration. Current efficiency decreased by 1.1 pct per each 100 mg/kg (ppm) increase in sulfur concentration in the electrolyte.

Fabrication and characterization of nanostructural WS2/WO3 binary compound semiconductors prepared by the sulfurization of sprayed thin films

We have investigated the impact of sulfurization and changing the metal salt ratio ([s]/[w] = 6–24 at.%) in the precursor solution on the structural, morphological, optical, electrical and photoconductivity properties of WS2/WO3 binary thin films grown on glass substrate by the spray pyrolysis technique. X–ray diffraction analysis showed that while the as-deposited samples present an amorphous nature, annealing these films in sulfur atmosphere generate a mix phase of WS2/WO3. FESEM study revealed the changes in surface morphology with increase in sulfur concentration in the spray solution. UV–Vis optical measurements analysis showed that these binary films have a relatively high absorption coefficient ~2 × 104–8 × 104 cm−1 in the visible spectrum with two distinct inflexions indicative of two transitions correspond to WS2/WO3 phases in agreement with the XRD analysis. The electrical studies showed that all these samples have a p-type conductivity; and the resistivity and photoconductivity decreases with increasing the sulfur to tungsten molar ratio.

Pathophysiological Concepts in Multiple Sclerosis and the Therapeutic Effects of Hydrogen Sulfide

Introduction:Multiple sclerosis (MS) is generally known as a manageable but not yet curable autoimmune disease affecting central nervous system. A potential therapeutic approach should possess several properties: Prevent immune system from damaging the brain and spinal cord, promote differentiation of oligodendrocyte progenitor cells (OPCs) into mature oligodendrocytes to produce myelin, prevent the formation of fibronectin aggregates by astrocytes to inhibit scar formation, and enhance function of healthy endothelial cells (ECs).Methods:To determine if an increase in sulfur contents through H2S, a potent antioxidant known to induce protective autophagy in cells, could provide the above desired outcomes, peripheral blood mononuclear cells (PBMNCs), OCPs, astrocytes, and ECs were treated with NaHS (50 μM) in vitro.Results:Transmigration assay using EC monolayer showed that serotonin increased migration of PBMNC while pretreatment of EC with NaHS inhibited the migration induced by serotonin treatment. NaHS upregulated proteins involved in immune system response and downregulated PBMNCs- and EC-related adhesion molecules (LFA-1 and VCAM-1). Furthermore, it had a cell expansion inducing effect, altering EC morphology. The effects of NaHS on OPCs and astrocytes were studied compared to mTOR inhibitor rapamycin. In NaHS treated astrocytes the induced fibronectin production was partially inhibited while rapamycin almost fully inhibited fibronectin production. NaHS slowed but did not inhibit the differentiation of OCPs or the production of myelin compared to rapamycin.Conclusion:The in vitro results point to the potential therapeutic application of hydrogen sulfide releasing molecules or health-promoting sulfur compounds in MS.

Electronic structure of purified Mo6S(9 − x)Ix nanowires studied by X-ray spectroscopy

The local electronic structure of purified Mo6S(9−x)Ix (x=6, 4.5) nanowires is investigated by X-ray absorption and fluorescence spectroscopies. The nanowires are found to be metallic with the density of states altered in both the conduction and the valence band depending on the stoichiometry. First-principle theoretical calculations suggest that the changes can be mainly attributed to the effect of strong MoS hybridization in the nanowires. The atomic chain structure of the nanowires is confirmed and the effect of increasing sulphur content is investigated.

Effect of sulfur on dielectric properties of Cd–Se Glassy system

Cd4Se96−xSx with x = 0, 4, 8, 12 amorphous semiconductor has been prepared by melt-quenching technique. Bulk samples in the form of powder were characterized by XRD which shows the amorphous nature of the prepared samples. The dielectric parameters were studied in the temperature range of 300–350 K and in the frequency range of 20 Hz–1 MHz. Dielectric dispersion are observed in the Cd–Se–S system, these results are explained on the basis of dipolar type of dielectric dispersion. It is also observed that DC conductivity increases and activation energy decrease with increase of sulfur concentration, which is mainly due to increase in the density of localized state in the mobility gap or decrease in the band gap.