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The synergistic solvent extraction of cobalt(II) from sulfate medium with N-(2-hydroxybenzylidene) aniline in association of two synergistic agents, the methyl-isobutyl ketone (MIBK) and 1-octanolin chloroform at 25 °C, has been studied. Synergistic and antagonistic effects are observed for the title metal at low and high concentration ratios of the synergistic agents. The synergistic extraction of cobalt(II) with the mixtures has been investigated with the methods of slope analysis. The extracted species with the mixtures are CoL2(S)2 and CoL2 (HL) (S) (L, denoted N-(2-hydroxybenzylidene) aniline ion and S denoted MIBK or 1-octanol). [ABSTRACT FROM AUTHOR]

The motive behind present work was to discover a solution for overcoming the problems allied with a deprived oral bioavailability of salbutamol sulfate (SS) due to its first pass hepatic metabolism, shorter half-life, and systemic toxicity at high doses. Pulmonary delivery provides an alternative route of administration to avoid hepatic metabolism of SS, moreover facilitated diffusion and prolonged retention can be achieved by incorporation into liposomes. Liposomes were prepared by thin film hydration technique using 32 full factorial design and formulation was optimized based on the vesicle size and percent drug entrapment (PDE) of liposomes. Optimized liposomal formulation exhibited an average size of about 167.2 ± 0.170 nm, with 80.68 ± 0.74% drug entrapment, and 9.74 ± 1.10 mV zeta potential. The liposomal dispersion was then spray dried and further characterized for in-vitro aerosol performance using Andersen Cascade Impactor. Optimized liposomal formulation revealed prolonged in-vitro drug release of more than 90% up to 14 h following Higuchi's controlled release model. Thus, the proposed new-fangled liposomal formulation would be a propitious alternative to conventional therapy for efficient and methodical treatment of asthma and alike respiratory ailments. [ABSTRACT FROM AUTHOR]

This research was focused on the measurements of ambient air pollutants species (Cl−, NO3−, and SO42−) concentrations of wet and dry depositions by using PS-1 (TSP), dry depositions plate and wet depositions tub at mixed (traffic, commercial, and residential) sampling sites. Lu-Liao, characterized by traffic, commercial and residential sites, was selected as the dry deposition measurement site. Hungkuang University, characterized by a traffic site, was selected as the wet deposition collection site. At the Luliao site, the results indicated that the average ionic species (Cl−, NO3−, and SO42−) concentrations were 12.86, 25.58, and 18.37 μg/m3, respectively, in winter and 2.94, 11.37, and 14.09 μg/m3, respectively in spring. The average ionic species (Cl−, NO3−, and SO42−) dry depositions were 284.43, 1808.50, and 412.93 μg/m2 min, respectively, in winter and 147.66, 109.59, and 415.44 μg/m2 min, respectively, in spring. As for the monthly Cl−, NO3−, and SO42− volume weighted mean (VWM) concentrations at the Hungkuang site, the results for January were 5.64, 4.41, and 10.13 mg/L, for May were 0.45, 1.98, and 2.09 mg/L, for June were 0.76, 1.39, and 2.46 mg/L, and for July were 1.83, 2.97, and 5.84 mg/L. The monthly Cl−, NO3−, and SO42− Fw (Fluxwet deposition) at the same site were 355.41, 277.63, and 638.15 mg/m2 month, respectively, for January; 17.01, 99.03, and 362.05 mg/m2 month, respectively, for May; 99.03, 181.18, and 319.45 mg/m2 month, respectively, for June; and 362.05, 587.86, and 1156.49 mg/m2 month, respectively, for July. SO42− had the highest VWM and Fw values when compared with the other ionic species, Cl− and NO3−. The highest VWM values for all ionic species (Cl−, NO3−, and SO42−) all occurred in winter. [ABSTRACT FROM AUTHOR]

The connection between sulphur (S) and selenium (Se) metabolism makes rapeseed (Brassica napus) an attractive candidate for Se fortification. Unfortunately, fertilizers may interfere with the availability of selenate (SeO42-) in numerous ways, including both soil and physiological processes. Experiments on two agricultural soils amended with SeO42- (32 μg Se kg−1 soil), sulphate and phosphate (each at three levels of supply) were established to elucidate the effect of these anions on the selenization efficiency. Maximal efficiency in Chernozem soil was roughly two-fold higher (455 μg Se kg−1 seed) than in Cambisol. Sulphate significantly decreased (up to 28%) the seed Se contents in Cambisol, while an enhancement (up to 33%) was found in Chernozem. In the Chernozem, the induction of collective S and Se translocation toward the seed more than compensated for any competition effects due to the highest sulphate supply. In Cambisol, plant Se distribution did not follow that of S as closely as in Chernozem. Phosphate did not significantly alter the fortification efficiency. Resistance of rapeseed proteins to protease hampered a quantitative investigation of changes in Se speciation under different S supplies. Nevertheless, protein-bound selenomethionine was the predominant Se storage form and traces of other Se species were also identified. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the short-term dynamics of chemical species of sulfate and the main basic cations in the soil solution affected by the application of different sulfur (S) rates using agricultural gypsum. The experiment was carried out in an Ultisol with 14% clay, managed under no-tillage for 14 yrs in Southern Brazil. Four rates of S (0, 5, 10 and 20 kg of S ha−1) were evaluated using agricultural gypsum (CaSO4) as S-source. The soil solution was collected using porous capsule lysimeters before and at 9, 17, 37, 60, 76 and 109 d after the gypsum application, at depths of 20 and 60 cm. Surface application of gypsum rapidly increases the sulfate concentration in the soil solution at 20 cm depth. However, in less than 30 d, the effect of the S rates on the soil solution at 20 cm was minimal, with an increase in sulfate concentration in the soil solution at 60 cm depth after 17 d. Sulfated fertilization via agricultural gypsum at rates greater than 10 kg ha−1 in sandy soil with low cation exchange capacity increased the mobility of Ca and Mg in the soil profile. [ABSTRACT FROM AUTHOR]

Usually the regulation defines the concentration of sulfates to consider aggressive soil or water. There are different standards to evaluate the resistance of concretes to the external sulfate attack. Most of these tests are based on the immersion of samples in solutions with high concentration of sulfates. But in the field, the concretes are also exposed to wet–dry cycles and the crystallization of salts can occur. In this work, 65 concretes manufactured with sulfate-resisting cements are tested. The cores were tested during 1 year submerged in sodium and calcium solutions for analyzing aspect, expansion, and variation of weight. After this, the cores were exposed to the same solutions semi-immersed for 2.5 years. After being semi-submerged for 1 year, some of the concretes revealed/showed alterations. After 2.5 years, around 15% of cores showed cracks and loss of material, due to formation of ettringite and thaumasite. [ABSTRACT FROM AUTHOR]

In this investigation, the dry–wet-cycled sulfate resistance and hydration products of steam-cured and standard-cured steel-slag mortars were investigated. Strength loss, porosity change, and microstructure of mortars prepared by replacing 20% of cement with steel slag (SS) were analyzed and compared with pure cement (PC) mortars. The results revealed that SS-blended cement mortar shows worse sulfate resistance than PC mortar regardless of the initial curing condition. Steam-cured PC mortar presents inferior sulfate resistance to standard-cured PC mortar, on the contrast, steam curing improves the sulfate resistance of SS mortar, when compared with the standard-cured mortars. Besides the large amount of C-S-H gels, the formation of hemicarbonate, C-A-S-H and relative lower CH content under steam curing can account for the improved sulfate resistance of initially steam-cured SS mortars, although the high porosity caused by steam curing brings negative impact to the sulfate resistance. [ABSTRACT FROM AUTHOR]

Sulfate anion is well-known for being one of the most active agents to be injected into the oil reservoirs and being capable of not only altering the interfacial properties of crude oil but also enhancing the water solution properties in oil recovery. In the current study, the effects of temperature and pressure were studied on interfacial tension (IFT) as well as the adsorption behavior of two different solutions containing sulfate anion using experimental measurements and modeling approaches. Although it was expected that IFT values of the studied systems might decrease as temperature increased due to the improvement in the molecule mobility and solubility of crude oil in water, which consequently might lead to the reduction in its free energy, the reverse trend was observed. The measured dynamic IFT values and adsorption behavior revealed that surface excess concentration of natural surfactants (ГNS) can be considered as the most effective parameter on interpreting IFT behavior as a function of temperature. [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of the methanogenic treatment of electronic industry wastewater containing tetramethylammonium hydroxide (TMAH), monoethanolamine (MEA) and sulfate in a lab-scale mesophilic up-flow anaerobic sludge blanket reactor. Feeding a mixture of electronic industry wastewater and co-substrate organics to the reactor for smooth acclimatization of sludge gave complete degradation of each organics within five days. When the reactor was fed only electronic industry wastewater, total COD removal, TMAH removal and MEA removal were achieved over 80, 99 and 99%, respectively, at an organic loading rate of 11.5 kg-COD m−3 day−1. 173 mg-S L−1 of influent sulfate was almost reduced simultaneously with the COD removal. In order to evaluate performance stability, the TMAH shock load event was performed under the conditions of 11,000 mg-COD L−1 for 24 h. Inflow of high TMAH concentration inhibited TMAH degradation and sulfate reduction for more than one month, however, not MEA. The batch feeding experiment and specific activity measurement revealed degradation pathways of each organics. TMAH was degraded via methanogenic pathway without sulfate reduction, MEA was degraded via methanogenic pathway with sulfate reduction. The results indicated that methanogenic treatment was applicable to electronic industry wastewater by appropriate reactor handling. [ABSTRACT FROM AUTHOR]

This work explores the effect of two metallic wastes (mining wastes, MW; fly ashes, FA) and micro-aeration (MA) on the anaerobic digestion of wastewater which is rich in sulfate and sulfide. Two initial COD concentrations (5,000 and 10,000 mg/L) were studied under both conditions in batch systems at 35 °C, with a fixed COD/SO42− ratio = 10, with 100 mg/L of S2−. It was observed that the use of MW and FA in the assays with an initial COD concentration of 10,000 mg/L resulted in a simultaneous increase in COD removal, sulfate removal, sulfide removal and methane generation, while MA only improved the COD and sulfide removals in comparison with the control system. On the contrary, the use of MW, FA or MA in systems with initial COD concentrations equal to or lower than 5,000 mg/L did not show any improvement with respect to the control system in terms of COD removal, sulfate removal or methane generation, with only sulfide removal being positively affected by MW and FA. [ABSTRACT FROM AUTHOR]

An experimental investigation was undertaken in order to assess the effect of sodium (Na2SO4) and calcium (CaSO4·2H2O) sulphates and curing period on stress–strain curves and failure modes of grey (GS) and red (RS) clayey soils stabilised by lime (L), natural pozzolana (NP) and their combinations (L–NP). Several soil–L–NP mixtures were studied to be used as subgrade soils for road pavements. Stress–strain curves were obtained from unconfined compressive strength (UCS) test made on several soil–L–NP specimens after curing for 7 and 120 days. Tests results showed that the use of L or L–NP without sulphates produced a significant increase in peaks stress of both clayey soils and then modified their stress–strain curves from nonlinear to linear behaviour almost up to 70% of peak stress after a longer curing period. However, the presence of 2% Na2SO4 or any CaSO4·2H2O content provided beneficial effects on peaks stress and stress–strain curves of both stabilised clayey soils and then improved their linearity almost up to 95% of peak stress after curing for 120 days. In contrast, the presence of 6% Na2SO4 caused undesirable effects. In addition, both sulphates greatly affected the failure modes of soil–L–NP specimens, particularly at a later stage. [ABSTRACT FROM AUTHOR]

Two green and simple spectrophotometric methods were developed for the determination of kanamycin sulfate (KNM) in its dosage forms. Method I is based on formation of a binary complex with eosin in citric phosphate buffer pH 3.5 and the product was measured at 548 nm. Method II depends on the reaction of KNM with vanillin in borate buffer pH 12 to produce a colored chromogen, which showed maximum absorbance at 404 nm. Different experimental variables influencing development and stability of the colored products were optimized. Validation of the developed procedures regarding linearity, ranges, precision, accuracy, robustness and limits of detection and quantification was performed. The absorbance-concentration plots were found linear over KNM ranges of 1-5 and 5-30 μg/mL for methods I and II respectively. The validated methods were successfully applied to the analysis of commercial suspension containing the drug. The main advantages of the proposed methods are being simple, inexpensive, green (done almost entirely in aqueous media) and with no requirement for laborious extraction procedures. [ABSTRACT FROM AUTHOR]

Pseudoephedrine is used for the temporary relief of stuffy nose and sinus pain/pressure caused by infection such as the common cold and flu. Here we were reporting a simple and precise validated stability indicating RP-HPLC method for estimation of Pseudoephedrine Sulfate and its related compounds in solid oral dosage forms. The stability indicating nature of current method has been demonstrated by a forced degradation study. All process related impurities and degradation products from forced degradation samples were well resolved from each other. The chromatographic separation of impurities was achieved with a Hypersil phenyl column (25 cm x 4.6 mm i.d., particle size 5 μ) using buffer and acetonitrile in the ratio of 95:5 v/v respectively as the mobile phase. The buffer used in mobile phase contained 10 mM potassium dihydrogen phosphate and its pH was adjusted to 3.0 ±0.05 with diluted orthophosphoric acid. The flow rate of HPLC was 1.0 mL min−1 and the wavelength of UV detector at 210 nm. The method was shown a linear response over range of 0.125 μg mL−1 to 0.750 μg mL−1 PES and impurities. The correlation coefficient was more than 0.999. Performed the robustness by using design experiments. [ABSTRACT FROM AUTHOR]

Context: AS FDSTs will provide an accessible alternative for AS autoinjector (ATROPEN®), and a noninvasive first-aid antidote for the treatment of organophosphate (OP) poisoning and reduce the number of fatalities due to nerve gas attacks or OP pesticide poisoning. Objective: The effects of changing the filler grade on the characteristics of atropine sulfate (AS) fast disintegrating sublingual tablets (FDSTs) and AS sublingual permeability were investigated in order to optimize the formulation of AS FDSTs and, therefore, AS sublingual permeability. Methods: Two batches of AS FDSTs containing AS 8 mg were formulated and manufactured using two different filler grades: microcrystalline cellulose (MCC) UF-702 (formulation A) and MCC PH-301 (formulation B). Several United States Pharmacopeia (USP) and non-USP physical tests were performed to evaluate the AS FDSTs' characteristics. The AS permeability from the two AS FDST batches were evaluated using Franz cells through excised porcine sublingual membranes. Results were statistically compared at p <.05. Results: Both batches passed the content uniformity and friability tests. Formulation A tablets were significantly different from formulation A tablets and resulted in better powder flowability, higher breaking force, faster disintegration, faster dissolution rate, higher water uptake, and higher AS permeability. Conclusion: The selection of the filler grade to be used in the formulation of AS FDSTs can significantly impact their characteristics and significantly affect AS sublingual permeability, which can be used to improve the sublingual delivery of AS and the potential of using AS FDSTs as an alternative dosage form for the first-aid treatment of OP poisoning. [ABSTRACT FROM AUTHOR]

We report results from a blind comparison of five analytical laboratories ISO/IEC 17025 (International Organization for Standardization/International Electrotechnical Commission) accredited for the analysis of sulfate collected in H2O2(aq) from industrial stacks in accordance with the European Standard Reference Method (SRM) for sulfur dioxide (SO2) (EN 14791): the method produced under European Commission mandate to support the enforcement of the Industrial Emissions Directive (IED). Both "synthetic" (sodium sulfate dissolved in aqueous hydrogen peroxide [H2O2(aq)]) and "real" (extracted and collected from a stack simulator facility in accordance with EN 14791) samples were prepared across 2–10 and 10–290 mg·m0−3 emission equivalent concentration ranges, respectively. From the measurements returned by the laboratories, it was found that in 35% of the former and 28% of the latter the stated expanded uncertainty limits did not intersect with the mean. It was also found with the real samples that in 30% of the 46 different concentration test levels the stated expanded uncertainty of at least two of the laboratories did not intersect. With respect to compliance monitoring, it was found that EN 14791 was capable of enforcing emission limits under the IED associated with waste incinerators (i.e., 50 mg·m0−3), as only 3% of the deviations were in excess of the required uncertainty (commensurate with a 95% level of confidence). However, with respect to the use of EN 14791 for calibration of automated measuring systems (AMSs), it was found that 38.5% of the deviations were in excess of the uncertainty recommended by at least one national regulator as being necessary for EN 14791 to be an "effective tool" for the calibration of AMSs. With emission limits under the IED and the Best Available Technique Reference (BREF) documents it adopts becoming increasingly stringent, it is clear that more work is needed to determine the capability of the SRM and also alternative methods based on portable instruments. Implications: The deviations observed between laboratories ISO/IEC 17025 accredited for sulfate analysis bring into question the monitoring communities' ability to routinely meet the uncertainty requirements associated with increasingly stringent SO2 emission limits under the European Union's Industrial Emissions Directive. Furthermore, with even further reductions in the near future due to legislative adoption of BREF documents, such issues are only likely to be exacerbated. If the European monitoring community is to have confidence in the capability of the existing Standard Reference Method described in EN 14791 for enforcing increasingly stringent limits, work is needed to validate this method at these lower emission levels. [ABSTRACT FROM AUTHOR]

Sediment historically impacted by acid mine drainage was exposed to different initial pH and electron donors to investigate the effect that both conditions had on the performance and fingerprint of the community from naturally acidic sediments. Batch experiments were fed with either acetate, lactate, or glycerol at initial pH of 5, 4, or 3, under sulfate-reducing conditions. The performance results indicated that sulfide production efficiency was above 85% in the treatments fed with lactate and glycerol at pH 5 and 4. However, acetate consumption efficiency was greater than 85% only in the treatments with acetate at pH 5 and lactate at pH 5 and 4. Glycerol fed treatments successfully produced sulfide even at initial pH = 3. Sulfide production rates were related to the initial pH in treatments fed with lactate and acetate and independent of the pH in the glycerol fed treatments. 16S rRNA gene T-RFLP analysis of the enriched communities indicated that the initial pH could explain the differences of the microbial community fingerprint obtained after 90 days. This study points out the fact that acidic stress is a heavy burden for the development of sulfate-reducing microorganisms, especially for those that use acetate as substrate. [ABSTRACT FROM AUTHOR]

In this study, the effects of polymeric ferric sulfate (PFS) and chitosan (CTS) on the dewatering characteristics of the digested activated sludge (e.g. filtrate turbidity, specific resistance of filtration (SRF), and cake moisture content) were investigated. The combined conditioning of PFS and CTS improved the settleability of the digested sludge more effectively than when using of PFS alone. The SRF value of the digested sludge decreased to 2.08 × 1012 m/kg after conditioning with 50 mg/g PFS and 10 mg/g CTS. Furthermore, a minimum moisture content of 68% was obtained when 40 mg/g PFS and 10 mg/g CTS were used to condition the digested sludge. At a fixed dose of PFS, the concentrations of extracellular polymeric substances, including polysaccharides (C/C0 = 2.1), proteins (C/C0 = 2.7), and deoxyribonucleic acids (C/C0 = 7.8) in the supernatant were increased considerably with an increase in CTS dose (0–10 mg/g). Phosphorus could be recovered efficiently as a result of charge neutralization and the adsorption-bridging effects of CTS, which promote the release of phosphorus from the digested activated sludge. The concentrations of heavy metals in the digested sludge conditioned with 40 mg/g PFS and 10 mg/g CTS satisfied the agricultural safety requirements. These results indicate that conditioning the digested sludge with combinations of PFS and CTS improves its dewatering performance and enables its direct use as a fertilizer. [ABSTRACT FROM AUTHOR]

The geotechnical properties of subgrade soils may need to be enhanced for appropriateness in pavement construction using mineral additives such as cement, lime (L) and fly ash. An experimental investigation was undertaken to study the effects of sodium (Na2SO4) and calcium (CaSO4·2H2O) sulphates on pH and pozzolanic reactions of soil–lime–natural pozzolana (soil–L–NP) mixtures in order to choose an adequate mixture for pavement subgrade soil stabilisation. The pH was measured for different curing periods with and without sulphates. The results showed that increases and decreases in pH values depend on the type of additive and its amount, type of sulphate and its content, mineralogical composition of stabilised soil and curing period. In addition, the pH parameter can be used as an indicator to track the pozzolanic reactions process. On the other hand, clayey subgrade soils can be stabilised with Lime–Natural Pozzolana (L–NP) mixtures containing any amounts of CaSO4·2H2O which is highly recommended. However, Na2SO4 with a low content has a better effect on the behaviour of these soils but become deleterious when its content is greater than 2%. In general, the addition of sulphates accelerates both the pozzolanic reactions and NP dissolution. [ABSTRACT FROM AUTHOR]

The impregnation of rice straw with 2-amino-3-(2-(4-chlorophenyl)hydrazinyl)-8,8-dimethyl-8,9-dihydropyrazolo[1,5-a]quinazolin-6(7H)-one (CPHPQ) has been used for the recovery of uranium from sulfate leach liquor. The uranium adsorption and elution of solvent impregnated mercerized rice straw (SIMRS) were carried out using a batch technique. The uranium adsorption controlling factors include pH, initial uranium concentration, contact time, S/L ratio, and temperature. Thermodynamic characteristics showed that the adsorption process is exothermic with enthalpy change ΔH = −152.1 kJ/mol. The kinetics data fit well with a pseudo-second-order model. The equilibrium data fit well with the Langmuir isotherm. Uranium cake was obtained from the eluate solution using hydrogen peroxide as UO4.2H2O precipitate. [ABSTRACT FROM AUTHOR]

Budesonide is a BCS class II drug with low water solubility (0.045 mg/mL) and low oral bioavailability (6–8%) due to high first pass effect. The aim is to prepare cross-linked chitosan–dextran sulfate nanoparticles and/or nanodispersion. Nebulizable cross-linked nanodispersion was prepared by the solvent evaporation technique and characterized through XRPD, FTIR, mean particle size (MPS), polydispersity index (PDI), zeta potential (ZP), drug loading, entrapment efficiency, SEM, % production yield, in vitro diffusion, aerodynamic and stability study. The optimization of formulation was done by using central composite rotatable design to study the effect of independent variables, concentration of chitosan (X1) and concentration dextran sulfate (X2) on the dependent variables, MPS (Y1), drug loading (Y2) and % CDR (% cumulative drug release) (Y3). The MPS, PDI, and ZP of budesonide-loaded nanoparticles were 160.8 ± 0.27 nm, 0.36 ± 0.04, and 13 ± 0.894 mV, respectively. The percent drug loading of all the batches was found in range of 10–16%. The emitted drug in target region (alveoli) was measured by using HPLC and it was found to be 18.26%. It was found that, nanodispersion had the optimum in vitro aerodynamic behavior. Stability study results showed no significant change in MPS, PDI, ZP, and % CDR after three month storage. In conclusion, cross-linked chitosan–dextran sulfate nanoparticles had properties suitable for nebulizable dispersion of increased drug loading, in vitro drug release and avoiding the first pass effect. [ABSTRACT FROM AUTHOR]

Salinity as a major agricultural problem can affect crop growth and quality. Onion (Allium cepa L.) plant contains a wide variety of sulfur-containing compounds which may be involved in plant protection against salt stress. In the current study, a similar reduction in growth caused by chloride and sulfate salts was observed when onion was exposed to equimolar concentrations of Na+. Also, no difference was observed for shoot/root ratio and dry matter content of roots and shoots. Plants accumulated Na+ and the respective anions (chloride and sulfate) which in turn caused changes in the content of other nutrients. The content of potassium and calcium was decreased more than the other elements by both sodium salts. Sulfate salinity resulted in substantial increase in total sulfur and sulfate content but chloride salinity affected neither the total sulfur nor sulfate content of the roots and shoots, only in onion exposed to 200 mM chloride salt, those of roots and shoots were reduced. Furthermore, the water-soluble non-protein thiol content as well as the content of alliin remained rather unaffected. In conclusion, either salts affected the uptake and distribution of sulfate in onion, but had no or only a minor effect on the plant sulfur metabolism. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate an innovative treatment route for gold-mining effluents rich in calcium, arsenic, and sulfate. This treatment route comprised two nanofiltration (NF) stages and a two-step intermediate precipitation. Arsenic and iron coprecipitation (first step) and calcium carbonate precipitation (second step) were assessed aiming to treat the first-stage NF concentrate and increase the permeate recovery rate in a second-stage NF. The pH, the molar ratio of Fe/As (first step), and the molar ratio of CO3/Ca (second step) were optimized by using rotational central composite design. Under optimal conditions, the arsenic removal was 99.8% (at pH = 7.0 and Fe/As = 4.0), and the calcium removal was 99.5% (at pH 11.5 and CO3/Ca = 3.5). The supernatant of Ca precipitation had very basic pH and had to be acidified before the second-stage NF. The pH 8.5 proved to be the best one regarding retention efficiency and flux. The flux decay of the second-stage NF was attributed to both osmotic pressure increase and reversible fouling resistance. It was concluded that the proposed treatment system is efficient for the treatment of gold-mining wastewater, ensuring higher production of treated effluent and an easy disposable of the final concentrate. [ABSTRACT FROM AUTHOR]

In field conditions, soil salinity may be due to an excess of different soluble salts. In order to compare the impact of chloride and sulfate salinities on rice, two contrasted cultivars (IKP: salt-sensitive and Pokkali: salt-resistant) were exposed to iso-strength Na+ nutrient solutions (NaCl 50 mM or Na2SO4 25 mM; EC: 5.31 dS m−1) for 2 weeks under controlled environmental conditions. It was found that NaCl was more toxic than Na2SO4, especially for the salt-sensitive IKP. Sodium and proline accumulation were higher while shoot osmotic potential was lower in NaCl-treated plants than in those exposed to Na2SO4. Chloride-treated plants exhibited a higher shoot malondialdehyde concentration, suggesting a higher level of lipid peroxidation while Na2SO4-treated plants presented a slightly higher total antioxidant activity. Pokkali was more tolerant than IKP to both types of toxicities although it accumulated similar concentration of toxic ions. Pokkali was able to reduce the root osmotic potential and to quickly recycle oxidized glutathione to reduced glutathione, which may help the plant to more efficiently control its oxidative status in stress conditions. It is concluded that different salts may have distinct impacts on the plant physiology and that differences may vary according to the considered cultivar. [ABSTRACT FROM AUTHOR]

The application of an integrated process configuration comprising of an ion exchange (IX) column and an upflow anaerobic sludge blanket (UASB) bioreactor for the simultaneous removal of SO42- and total Se from synthetic mine wastewater was evaluated. Use of an IX column as a pre-treatment (not as post-treatment) to the UASB bioreactor gave the best overall removal performance. The combined treatment reduced the total Se and SO42- concentration from 8.0 and 1441 mg/L to 0.2 and 28.0 mg/L, respectively. This study demonstrated for the first time that an IX process as a pre-treatment to a biological process can significantly improve the oxyanion removal efficiency and the overall treatment of Se-laden wastewaters. [ABSTRACT FROM AUTHOR]

The production of sulfur (S) from the biological oxidization of sulfide (S2−) by SOB (sulfide-oxidizing bacteria) allows for resource recovery. Past researches have indicated that S recovery from S2− oxidation MABR (the membrane aerated biofilm reactor) was feasible. The process was complicated by the requirement of maintaining appropriate oxygen supply to prevent the produced S from being further oxidized into sulfate () and by the presence of heterotrophic biomass. In this study, a multispecies biofilm model was developed and experimentally validated to gain insight for the S recovery process in MABR. The developed model was capable of predicting the S recovery performance in the MABR. The optimal conditions involved in maintaining the appropriate oxygen flux and the biofilm thickness according to the hydraulic and S2− loading rate. The low anoxic heterotrophic growth rate using and S as electron donors could explain why the impact of heterotrophic growth was insignificant. [ABSTRACT FROM AUTHOR]

In this study, a physically and chemically based model including thermodynamic equilibrium, kinetic control and surface complexation is used. Different cases are proposed and simulated with the same set of parameters. The results are compared with experimental data. They show very good agreement between experimental and numerical results. They also show that the parameters are not very sensible to cement composition, concrete mix-design or environmental exposition. Hence, this numerical model seems to be used as a reliable tool to predict the chloride binding capability and external sulphate attack. It is also convenient because of its limited number of parameters. [ABSTRACT FROM AUTHOR]

Aqueous two-phase partitioning system (ATPS) was used to extract and purify catalase from Bacillus pumilus. The system parameters for effective purification of catalase were optimized. The best catalase recovery (123%) with a 4.6-fold purification was obtained in the bottom phase of ATPS including the mixture of 15% (w/w) PEG4000, 10% (w/w) Na2SO4 and 3% (w/w) NaCl at pH 5.0. The purified enzyme was characterized regarding its activity and stability. The highest enzyme activity was observed at pH 7.0 and 37 °C on hydrogen peroxide. The enzyme was quite stable at temperatures between 30 and 55 °C and a pH range of 7.0–9.0. The Km and Vmax values were determined from Lineweaver–Burk plot as 11 mM and 1667 µmole ml−1 min−1, respectively. Overall, it can be said that ATPS is a rapid, reasonable, straightforward and cost-effective process for catalase purification in comparison to the chromatographic methods. [ABSTRACT FROM AUTHOR]

Barium sulfate, strontium sulfate and barium-strontium sulfate nanoparticles were obtained by the addition of metal chloride(s) (metal = barium/strontium/barium-strontium) to sodium sulfate by conventional precipitation method. To overcome the limitations of conventional precipitation method, we have prepared barium dodecyl sulfate/strontium dodecyl sulfate/barium-strontium dodecyl sulfate by mixing metal chloride(s) (metal = barium/strontium/barium-strontium) with sodium dodecyl sulfate (SDS) as precursors. Barium dodecyl sulfate/strontium dodecyl sulfate/barium-strontium dodecyl sulfate obtained above on decomposition generates barium sulfate/strontium sulfate/barium strontium sulfate having different morphologies and nano sized particles. The samples were characterized using powder X-ray diffraction technique, infrared spectroscopy and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

In this study, waste rock of iron ore mine (metasomatic rocks) has been modified and utilized as a sulfate adsorbent to enhance sulfate removal from contaminated aqueous solution. The modification generating from the assembly of Mg-Al and Ni-Al layered double hydroxides and metasomatic rocks. The sulfate adsorption onto both adsorbents was performed favorably as a monolayer adsorption in homogeneous condition. The kinetic studies identify the chemisorption mechanism of sulfate adsorption process onto both adsorbents with the combination of the film-mass transfer and internal diffusion. Thermodynamic studies indicate that sulfate adsorption process onto both adsorbents was exothermic and spontaneous. [ABSTRACT FROM AUTHOR]

AIMS: To compare the effect of two partial mixed ration diets containing either sulfate or chloride-based anionic salts, fed to grazing prepartum dairy cows, on concentrations of Ca, Mg, P and beta-hydroxybutyrate (BHB) in plasma, disease incidence and milk yield during the early postpartum period. METHODS: The study was conducted on a seasonal-calving grazing dairy farm located in Benton (MO, USA). In August 2016, two groups of 200 cows were randomly assigned at 30 days before expected parturition to receive either a sulfate or chloride-based anionic diet, to achieve a dietary cation-anion difference (DCAD) of −25 mEq/kg DM. Cows were fed partial mixed rations to provide 50% of their DM intake, with 50% provided by grazing fescue pasture. Urine samples were collected from 20 cows from each group once a week for 5 weeks until calving for pH assessment. At parturition, 42 cows per group were selected at random and blood samples collected on Days 1, 2, 3 and 7 postpartum. The study continued until 100 cows per group calved. Health events and cumulative milk yield until 30 days postpartum were recorded. Concentrations of Ca, P, and Mg in plasma at Days 1, 2, 3, and 7, and BHB in plasma at Day 7 postpartum were assessed. RESULTS: Mean urine pH was lower in cows in the chloride than sulfate group (p≤0.06) on four of five sampling occasions. Mean concentrations of Ca in plasma on Day 1 were 2.00 (95% CI=1.94-2.05) and 1.91 (95% CI=1.88-1.97) mmol/L for the chloride and sulfate groups, respectively (p=0.15), and on Day 3 were 2.03 (95% CI=1.97-2.08) and 1.90 (95% CI=1.84-1.96) mmol/L, respectively (p=0.038). Concentrations of Mg, P and BHB in plasma and incidence of diseases postpartum were similar in both groups (p>0.05). There were no cases of clinical hypocalcaemia in either group. CONCLUSIONS AND CLINICAL RELEVANCE: Prepartum cows fed a partial mixed ration with a negative DCAD containing chloride-based anionic salts and free access to a fescue pasture had lower prepartum urine pH, and higher concentrations of total Ca in plasma during the first week postpartum, than cows receiving a partial mixed ration containing sulfate-based anionic salts. [ABSTRACT FROM AUTHOR]

Biodiesel production costs can be significantly reduced by using nonrefined feedstock. Sulfated solid catalysts have been proposed for producing biodiesel from acid oils by esterification reactions. Nevertheless, leaching of sulfate species to the reaction medium may occur, but often it is not considered. In this article, a commercial tin sulfate (SnSO4) was used as a catalyst for the esterification of a feedstock with high content of free fatty acid in order to assess the contribution of the homogeneous catalysis in different situations. SnSO4 was calcined at different temperatures (300, 400, 500 and 700 °C) and converted into SnO2 after calcination at temperatures higher than 300 °C. Homogeneous catalysis seems possible to occur with all of the catalysts, but it was clearly observed for the uncalcined catalyst (SnSO4) and for that calcined at 300 °C (SnSO4(300)). For these catalysts, an important leaching of the sulfate species was confirmed. Higher conversions were obtained with the uncalcined SnSO4. Reactions at the same conditions using sulfuric acid as catalyst at concentrations of 0.1% were performed and confirmed conversions higher than 80%. Heterogeneous catalysis plays a significant role only with the catalyst that present the highest specific surface areas and acidity (SnSO4(400)). As some small amount of sulfate species is retained in the structure or surface of the calcined catalysts (even after calcination at 700 °C), we cannot exclude the possibility that these species are also leached during reaction. Thus, a possible contamination of biodiesel through the use of sulfated catalysts cannot be ruled out. [ABSTRACT FROM AUTHOR]

The article focuses on the history of the discovery of the mammothite, a rare multimetal oxy-hydroxide-sulfate that can be found in three countries such as the U.S., Italy and Greece. It states that the mammothite is considered a new specie and was named after the Mammoth vein, one of the main ore horizons in Mamoth, Arizona. It also offers brief history of the summary of the main ownership dates of the stone.

Artificial neural network and response surface methodology have been used to develop a model for simulation and optimization of the removal of Nile blue sulfate by heterogeneous Fenton oxidation. Experimental data were used to train an artificial neural network model with linear transfer function at the output layer and a tangent sigmoid transfer function at the hidden layer. A Box–Behnken design was employed to assess the effects of input process parameters on the total organic carbon removal. First order kinetics and lumped kinetics models were used to describe the reaction; a high regression coefficient indicated that the latter fitted best. The formation of non-oxidizable compounds was shown by liquid chromatography–mass spectrometry. [ABSTRACT FROM AUTHOR]

Climate engineering with stratospheric sulfate aerosol injections (SSAI) has the potential to reduce risks of injustice related to anthropogenic emissions of greenhouse gases. Relying on evidence from modeling studies, this paper makes the case that SSAI could have the potential to reduce many of the key physical risks of climate change identified by the Intergovernmental Panel on Climate Change. Such risks carry potential injustice because they are often imposed on low-emitters who do not benefit from climate change. Because SSAI has the potential to reduce those risks, it thereby has the potential to reduce the injustice associated with anthropogenic emissions. While acknowledging important caveats, including uncertainty in modeling studies and the potential for SSAI to carry its own risks of injustice, the paper argues that there is a strong case for continued research into SSAI, especially if attention is paid to how it might be used to reduce emissions-driven injustice. [ABSTRACT FROM AUTHOR]

Introduction: Abuse-deterrent formulations have been developed to reduce inappropriate opioid use. The aim of this paper is to review existing literature about currently available morphine abuse-deterrent formulations. Areas covered: The US FDA has currently attributed an 'abuse-deterrent formulation' label to two different morphine compounds: an agonist/antagonist combination, and a morphine formulation with physical barrier. The combination of morphine sulfate and naltrexone showed bioequivalence with extended release morphine. Naltrexone was found in low levels or non-detectable in most of the patients. If the capsules are tampered, the orally available naltrexone would be released, causing a decreased euphoria expected by the use of morphine. The application of physical and chemical barriers to the active compound aims at preventing manipulation of the opioid tablet. This abuse-deterrent formulation obtained with a physical barrier did not reduce drug liking compared to ER morphine. Expert commentary: Available data from literature suggest that both formulations may offer an alternative with lower abuse potential in the treatment of chronic pain. Nevertheless, current evidence suggests that only a little percentage of abusers may stop abusing drugs as result of reformulation. More post-marketing studies are advocated to evaluate the real impact of abuse-deterrent formulations. [ABSTRACT FROM AUTHOR]

Four unplasticized, commercially available cellulose acetate (CA) powders were artificially aged for up to 30 weeks in a humid oven at 70°C and 50% relative humidity (RH) to see if higher levels of residual sulfate groups (−OSO2OH)− attached to the cellulose backbone affected degradation. Qualitative x-ray fluorescence (XRF) of unaged powders showed that three contained the same amount of sulfur while the fourth exhibited more. Three powders were manufactured recently whereas the fourth was produced in the 1970s. Powders were aged in lidded borosilicate glass bottles to impede evaporation of acids generated during artificial aging. A water reservoir was enclosed within each bottle to help maintain humidity. Changes to the level of acidity and sample weight were characterized at various time points. All samples emitted acid vapor with aging yet the powder with higher residual sulfate content emitted the most. Similarly, with aging, only the powder with higher level of sulfur content showed a weight loss. No unique behavior was observed from the powder that had naturally aged for forty years before being artificially aged. [ABSTRACT FROM AUTHOR]

The N-dodecyl chitosan sulfate (NDCS) with a higher degree of substitution of dodecyl was synthesized. The surface tension and transmission electron microscopy showed that the product had a higher surface activity and could self-assemble into bigger spherical polymeric micelles. Besides, the characteristics of complexation of NDCS with cetyltrimetylammonium bromide (CTAB) were studied by static/dynamic surface tension, turbidity and transmission electron microscopy. The results revealed that the mixture of NDCS with CTAB had a higher surface activity, lower diffusing rate and higher turbidity. Furthermore, they also could self-assemble into agglomerate or dispersed spherical aggregates in some concentration domain of CTAB. [ABSTRACT FROM AUTHOR]

The present work aimed at research the physic-chemical properties of the interaction of N-decyl-O-chitosan sulfate (an amphiphilic chitosan derivative, C10-OCHS) with cetyltrimetylammonium bromide (CTAB) by the steady-state fluorescent, static/dynamic surface tension, turbidity and transmission electron microscopy (TEM). The results showed that the complex of C10-OCHS/CTAB had high surface activity and lower critical aggregation concentration. Besides, the C10-OCHS/CTAB could self-assemble into various aggregates like irregular spherical aggregates, vesicles or polydisperse aggregates from lower to higher concentrations of CTAB with a mixed C10-OCHS concentration of 200 mg/L. [ABSTRACT FROM AUTHOR]

Sulfate attack is one of the major durability problems in concrete structures, but there is less research on sulfate attack of concrete with initial damage. In this paper, the deterioration law of concrete with damage degrees under combined actions of sulfate attack and drying-wetting cycles were investigated through mass change and relative dynamic elastic modulus (Erd). The pore structure and corrosion products of the concrete exposed to sodium sulfate solution under drying-wetting cycles were also investigated by MIP and SEM/EDS, respectively. The results revealed that the mass change and Erd of concrete with damage were greater than that of concrete without damage; the high content of slag in concrete can increase the resistance sulfate attack and the low content of slag reduce sulfate resistance of concrete. As time increases, the porosity and the number of large pores of concrete with damage increased. The internal corrosion products of concrete with high water-to-cement ratio were mainly gypsum, and the internal corrosion products of concrete with low water-to-cement ratio were mainly ettringete. [ABSTRACT FROM AUTHOR]

A practical and efficient asymmetric synthesis of (S)-dihydrokavain from known ethyl (S)-2-hydroxy-4-phenylbutanoate which is, in turn, readily available from L-malic acid as a cheap chiral pool material is described using regioselective ring-opening of the 1,2-cyclic sulfate with lithium-3,3,3-triethoxypropiolate and subsequent HgO/H2SO4-mediated lactonization as the key steps. Its opposite enantiomer (R)-dihydrokavain was also synthesized from D-malic acid using the same sequences of reactions for the purpose of optical purity determination. [ABSTRACT FROM AUTHOR]

A newly synthesized chitosan stearoyl thiourea derivative is first used for the preconcentration of uranium from sulfate solution prior to its spectrophotometric determination. The effect of optimal adsorption and elution conditions was studied. The equilibrium data were found to be satisfactorily fitting to Langmuir isotherms with a maximum adsorption capacity of 98.75 mg/g. Kinetics and thermodynamics studies showed an exothermic pseudo-first-order adsorption process. Interference studies showed a high tolerance of diverse ions. The proposed method was validated and successfully applied for the determination of uranium in certified reference samples and ore samples with satisfactory results. [ABSTRACT FROM AUTHOR]

Plant extracts and streptomycin sulfate were evaluated against Xanthomonas axonopodis pv. citri. In first experiment, Azadirachta indica, Allium cepa, Catharanthus roseus, Allium sativum, Zingiber officinale (Roscoe) were investigated in vitro through inhibition zone technique against the growth of X. a. pv. citri. Results indicated that A. indica exhibited statistically significant inhibition (4 cm) zone over control. In second experiment, A. indica and streptomycin sulfate disjointedly and in amalgamation were evaluated in vitro. Streptomycin alone and in permutation with A. indica articulated significant inhibition of the bacterium. In third study, streptomycin sulfate and A. indica (S) and in combination were evaluated against citrus canker disease in green house. Results showed that streptomycin sulfate reduced disease significantly than control. In fourth experiment, streptomycin sulfate, A. indica, in combination and their interaction with days were evaluated under field condition. Streptomycin sulfate proved to be most effective and reduced the disease severity as compared to control. [ABSTRACT FROM AUTHOR]

A small library of neutral peptide-based anion receptors was synthesised, where changes were made to the scaffold structure to investigate the effect these structural features have on the anion binding ability of these receptors. These changes included shortening the peptide side chain lengths, increasing the number of electron withdrawing substituents present on the squaramide phenyl substituents and increasing the length and flexibility of the peptide backbone. An effort was also made to increase the aqueous solubility of these receptors by functionalising the N-terminus of the peptide with a hydrophilic moiety. All the receptors displayed strong affinity and selectivity for sulfate in 20% v/v H2O/DMSO-d6 and a 5-fold increase in the affinity of the thiourea receptors was observed upon shortening the side chains by one methylene unit. Overall, the squaramide derivatives displayed much stronger association, in this competitive media, than the thiourea based receptors. [ABSTRACT FROM AUTHOR]

The size distribution and chemical components of a fine fraction (<2.5 μm) of road dust collected at urban sites in Korea (Gwangju) and Mongolia (Ulaanbaatar) where distinct urban characteristics exist were measured. A clear bimodal size distribution was observed for the resuspended fine road dust at the urban sites in Korea. The first mode peaked at 100-110 nm, and the second peak was observed at 435-570 nm. Ultrafine mode (~30 nm) was found for the fine road dust at the Mongolia site, which was significantly affected by residential coal/biomass burning. The contribution of the water-soluble ions to the fine road dust was higher at the sites in Mongolia (15.8-16.8%) than at those in Korea (1.2-4.8%). Sulfate and chloride were the most dominant ionic species for the fine road dust in Mongolia. As (arsenic) was also much higher for the Mongolian road dust than the others. The sulfate, chloride, and As mainly come from coal burning activity, suggesting that coal and biomass combustion in Mongolia during the heating season should affect the size and chemical components of the fine road dust. Cu (copper) and Zn (zinc), carbonaceous particles (organic carbon [OC] and elemental carbon [EC]) increased at sites in Korea, suggesting that the fine road dust at these sites was significantly affected by the high volume of traffic (engine emission and brake/tire wear). Our results suggest that chemical profiles for road dust specific to certain sites should be applied to more accurately apportion road dust source contributing to the ambient particulate matter. Implications: Size and chemical characteristics of fine road dust at sites having distinct urban characteristics were examined. Residential coal and biomass burning and traffic affected physiochemical properties of the fine road dust. Different road dust profiles at different sites should be needed to determine the ambient PM2.5 sources more accurately. [ABSTRACT FROM AUTHOR]

Methane (CH4) oxidation plays an important role in regulating the atmospheric CH4 balance. Although nitrogen (N) enhancement and sulphate () deposition are major environmental problems facing the Min River estuary in subtropical China, the interactive effects of N and on CH4 oxidation remain poorly understood. We conducted an incubation experiment to investigate the effects of N and additions on CH4 oxidation in marsh soils. CH4 oxidation exhibited distinct seasonal variations, which correlated with changes in temperature and soil moisture; in addition, CH4 oxidation rates were enhanced by the addition of nitrate (), but were slightly inhibited by the addition of ammonium () and . The combined effects of N and on CH4 oxidation were controlled primarily by the form of N, which may imply that inhibition of CH4 oxidation with addition may be counteracted by N addition, especially in estuarine marsh soils with low N and high concentrations. We propose that, although was more effective in stimulating CH4 oxidation and the inhibition caused by and was minor, CH4 oxidation may be inhibited because was dominant and accompanied by strong deposition in the Min River estuary. As such, future CH4 emissions from estuarine wetlands may increase as a result of higher inputs of and . [ABSTRACT FROM AUTHOR]

A series of new hyaluronan derivatives was synthesized and tested as an antibiotic release system by antibacterial and osseointegration assays. Specifically, partially sulphated hyaluronic acid (sHA) was functionalized with dopamine (DA). The DA moiety guarantees good performance as a binding agent for coating a titanium alloy surface; furthermore, the negatively charged sHA has bone regenerative effects and a high binding affinity for positively charged antibiotics. A sHA scaffold with a defined degree of sulphation (DS =2) was selected as a good compromise between a high negative charge density and poor heparin-like anticoagulant activity, while the degree of DA derivatization (17.1%mol) was chosen based on the absence of cytotoxic activity and the promotion of osteoblast proliferation. The titanium alloy coating was investigated indirectly using a fluorescent probe and directly by environmental scanning electron microscope (ESEM) analysis. Long-duration antibiotic release was demonstrated in vitro, and antibacterial efficacy against a Staphylococcus aureus culture was shown. [ABSTRACT FROM AUTHOR]

The objective of this study is to utilize an expanded granular sludge bed reactor for removing heavy metals and sulfate from synthetic acid-mine drainage (AMD) using sewage sludge fermentation centrate as the substrate. The reactor was bioaugmented with an enriched consortium of sulfate-reducing bacteria (SRB). The bioreactor performance was studied with different chemical oxygen demand ratios, liquid upflow velocity (Vup), hydraulic retention time (HRT) and influent pH. The highest COD, sulfate and heavy metal removal efficiencies were achieved at a ratio of 1.5, Vup of 4.0 m/h, HRT of 15 h and influent pH of 6.0 (68.2%, 92.1% and 100%, respectively). The activity of SRB greatly increases the effluent pH. Even at an influent pH of 3.0, 60.8% of sulfate, 41.3% of COD and 91.2% of heavy metals could be removed, and the effluent quality can meet the national discharge standard of China. The activity tests demonstrate that the sludge fermentation centrate is an excellent carbon source for SRB. This study shows the potential of synchronous treatment of residual sewage sludge and treatment of AMD. [ABSTRACT FROM AUTHOR]

1. Methylone (3,4-methylenedioxy-N-methylcathinone, MDMC), which appeared on the illicit drug market in 2004, is a frequently abused synthetic cathinone derivative. Known metabolic pathways of MDMC include N-demethylation to normethylone (3,4-methylenedioxycathinone, MDC), aliphatic chain hydroxylation and oxidative demethylenation followed by monomethylation and conjugation with glucuronic acid and/or sulphate. 2. Three new phase II metabolites, amidic conjugates of MDC with succinic, glutaric and adipic acid, were identified in the urine of rats dosed subcutaneously with MDMC.HCl (20 mg/kg body weight) by LC-ESI-HRMS using synthetic reference standards to support identification. 3. The main portion of administered MDMC was excreted unchanged. Normethylone, was a major urinary metabolite, of which a minor part was conjugated with dicarboxylic acids. 4. Previously identified ring-opened metabolites 4-hydroxy-3-methoxymethcathinone (4-OH-3-MeO-MC), 3-hydroxy-4-methoxymeth-cathinone (3-OH-4-MeO-MC) and 3,4-dihydroxymethcathinone (3,4-di-OH-MC) mostly in conjugated form with glucuronic and/or sulphuric acids were also detected. 5. Also, ring-opened metabolites derived from MDC, namely, 4-hydroxy-3-methoxycathinone (4-OH-3-MeO-C), 3-hydroxy-4-methoxycathinone (3-OH-4-MeO-C) and 3,4-dihydroxycathinone (3,4-di-OH-C) were identified for the first time in vivo. [ABSTRACT FROM AUTHOR]

This study was intended to investigate the properties of Cr/Cr bilayer coatings. These coatings were deposited on a copper substrate by the DC electrodeposition method from Cr(III) sulphate baths with additions of formate-urea or glycine as complexing agents. Examination of the surface morphology of Cr coatings with SEM has shown that both single and bilayer Cr coatings obtained in the Cr(III) bath with formate-urea, and those obtained in the Cr(III) bath with glycine are cracked. It has been determined that the surface microhardness (HV) of bilayer Cr coatings obtained in the Cr(III) bath with glycine is higher compared with that of single-layer Cr coatings. Wear testing of the coatings was undertaken against an Al2O3 ball counterface (6 mm diameter) at 1N load. The results indicate that the friction coefficients (COF) of bilayer Cr/Cr coatings obtained in the Cr(III) bath with formate-urea increased from 0.2 to 0.5 compared with that of single-layer Cr coatings, while their wear resistance deteriorated. However, bilayer Cr/Cr coatings obtained in the Cr(III) bath with glycine exhibit wear resistance close to that of single coatings with COF equal to 0.05. [ABSTRACT FROM AUTHOR]

The views expressed in this presentation are those of the author and do not reflect the official policy of the Department of the Army/Navy/Air Force or the Department of Defense The identification of specific products or scientific instrumentation does not constitute an endorsement or implied endorsement on the part of the authors, DoD, or any component agency. While we generally excise references to products, companies, manufacturers, organizations, etc. in government produced works, the abstracts produced and other similarly situated researchers presents a special circumstance when such product inclusions become an integral part of the scientific endeavor. [ABSTRACT FROM AUTHOR]