Sulfate Complexes Research Articles

Uranyl speciation in sulfate-bearing hydrothermal solutions up to 250 °C

The speciation of uranyl in sulfate-bearing solutions at temperatures up to 250 °C has been investigated using in situ UV–Visible spectrophotometry. Formation constants for the reactions UO22++SO42-⟺UO2SO40 (logβ1= 3.38, 4.40, 5.44, 6.33, 7.74) and UO22++2SO42-⟺UO2SO422- (logβ2 = 4.10, 5.26, 6.83, 8.00, 9.70) were derived at 25, 100, 150, 200 and 250 °C respectively. These formation constants were fitted to the modified Ryzhenko–Bryzgalin (MRB) model to derive pK(298), A(zz/a) and B(zz/a) values for both complexes: 3.262, 2.212, −197.96 (UO2SO40) and 4.189, 3.21, −473.14 UO2SO422- respectively. Compared with values extrapolated using previously available data for 25, 70 and 75 °C, our new data suggest higher stability of UO2SO40 at temperatures above 150 °C and significantly lower stability of UO2SO422- at all temperatures above 25 °C. Molar absorbances of both sulfate species were also derived. At 25 °C we found our molar absorbance for UO2SO40 agreed well with those reported previously in the literature, however we report lower peak amplitudes for UO2SO422-. We also noted significant temperature-dependent red shifts in the molar absorbance of UO2SO40. We suggest that these shifts could be explained by changes in sulfate bonding behaviour around the uranyl ion – namely shifts in the distribution of complexes with sulfate bound in either a monodentate or bidentate configuration. Simple models calculated with our new data suggest that sulfate complexes may readily predominate over chloride complexes even in solutions containing upwards of 20 wt% chloride and only 100 ppm sulfate. In addition, moderate concentrations of sulfate (∼1 wt%) can increase the solubility of uranium by an order of magnitude. Thus we suggest that sulfate could play an important role in mobilising uranium in hydrothermal systems, and that the removal of sulfate via precipitation of sulfate minerals may act as a means of depositing uranium under oxidizing conditions. This in turn might explain the associations between sulfate minerals and uranium mineralisation occasionally seen in large uranium ore deposits such as Olympic Dam and MacArthur River.

Novel Cu1‐xZnxS (x=0,0.01, …, 0.1) Nanoparticles: Synthesis, Spectroscopic Analysis, Photocatalytic and Anticancer Activities

AbstractAbstract: CuS (CS) and Cu1‐xZnxS (CZS) nanoparticles (NPs) were synthesized for the first time by a hydrothermal method from decomposition of tris(thiourea) copper (I) sulphate complex with zinc nitrate hydrate for 8 hours at 140 °C. The products have been identified by using X‐Ray diffraction analysis (XRD). These XRD patterns showed that the CS and CZS nanoparticles have a well‐ordered covellite structure with high purities. Field emission scanning electron microscope (FESEM) showed that by increasing dopant concentration, the size of Cu1‐xZnxS (x=0.01, 0.05, 0.1) nanoparticles is increased. Optical properties and band gaps were calculated with diffuse reflectance spectra (DRS) and photoluminescence (Pl), so nanoparticles with high dopant concentration (x=10%) had less band gap values. In photocatalyst studies, the CZS (x=10%) species can remove 95% Methylene Blue (MB) in the presence of H2O2 under UV light in 90 minutes. Furthermore, the CZS (x=1% ‐ 10%) NPs have excellent potential to eliminate of Hep G2 cancer cells.

Adsorption of uranium from its aqueous solutions using activated cellulose and silica grafted cellulose

Abstract The present work provides a thorough description of the preparation of two cellulose anion exchange resins. In addition, the application of the prepared resins for treatment the uranium-contaminated wastewater. In the preparation, the first resin was cellulose reacted with 0.3 M HNO3 to produce Activated Cellulose (AC), while the second was AC treated with sodium metasilicate and phosphoric acid to yield Silica Grafted Cellulose (SGC). The efficiency of the two prepared resins for uranium adsorption from aqueous solution was testifying on a batch scale. In solutions of pH ranging from 4 to 7, results showed a high exchange rate and uptaking capacity up to 105 mg/g. However, the addition of NO3 −, Fe3+ and Th4+ ions to the target media has an adverse impact on the uranium sorption for AC adsorbent. Otherwise, the addition of uranyl sulfate complexes could ameliorate Fe3+ and Th4+ adsorbed into the SGC.

Luminescence properties and kinetic parameters of nanocrystalline BaxSr1-xSO4:Dya%,Tbb% powder under gamma excitation

In this study, nanocrystalline barium strontium sulfate complex BaxSr1-x(=0.12,0.50,0.88,0.94)SO4:Dya(=0.1,0.2,0.5,1.5%),Tbb(=0.2,0.4,1,1.5%) powders were prepared via a chemical co-precipitation method at room temperature. The nanocrystalline powders were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, UV–visible spectrometry, thermoluminescence (TL), and photoluminescence. Under gamma ray irradiation, the maximum intensity of the TL glow curves for BaxSr1-xSO4:Dy0.1%,Tb0.2% was obtained with x = 0.88. The nanocrystalline Ba0·88Sr0·12SO4:Dy1.5%,Tb1% powder was selected because of its high intensity glow curve with a good shape. The TL response of Ba0·88Sr0·12SO4:Dy1.5%,Tb1% after irradiation with different gamma doses exhibited linear behavior from 0.01 to 7 kGy and 1–15 kGy. A glow curve deconvolution method and MATLAB software were used to calculate the TL kinetic parameters and the results obtained were investigated in detail. Moreover, the emission spectra obtained for the Ba0·88Sr0·12SO4:Dy1.5%,Tb1% and Ba0·88Sr0·12SO4:Dy0.5%,Tb1.5% nanocrystalline powders at an excitation wavelength of 350 nm showed that the efficiency of the energy transfer from Dy3+ to Tb3+ ions was increased by increasing the Tb3+ ion concentration in Ba0·88Sr0·12SO4.

Investigation of Uranyl Sulfate Complexation under Hydrothermal Conditions by Quantitative Raman Spectroscopy and Density Functional Theory

Quantitative first and second formation constants of aqueous uranyl sulfate complexes were obtained from Raman spectra of solutions in fused silica capillary cells at 25 MPa, at temperatures ranging from 25 to 375 °C. Temperature-dependent values of the symmetric O-U-O vibrational frequencies of UO22+(aq), UO2SO40(aq), and UO2(SO4)22-(aq) were determined from the high-temperature spectra. Temperature-independent Raman scattering coefficients of UO22+(aq) were calculated directly from uranyl triflate spectra from 25 to 300 °C, while those of UO2SO40(aq) and UO2(SO4)22-(aq) were derived from spectroscopic data at 25 °C and concentrations calculated using the formation constants of Tian and Rao ( J. Chem. Thermodyn. 2009 , 41 , 569 - 574 ), together with the Specific Ion Interaction Theory (SIT) activity coefficient model. Chemical structures and vibrational frequencies predicted from Density Functional Theory (Gaussian 09) were employed to interpret the Raman spectra. Values of the cumulative formation constants ranged from log β1 = 3.23 ± 0.08 and log β2 = 4.22 ± 0.15 at 25 °C, to log β1 = 12.35 ± 0.22 and log β2 = 14.97 ± 0.02 at 350 °C. This is the first reported use of high-pressure fused silica capillary cells to determine formation constants of metal ligand complexes from their reduced isotropic Raman spectra under hydrothermal conditions.

Recovery of rare earth metals and synthesis of Ni0.6Co0.2Mn0.2(OH)2 from spent asymmetric-capacitance power batteries

Abstract There is a pressing need to recover asymmetric-capacitance nickel-metal hydride power batteries (AC-NiMH) owing to their large number of applications. However, recycling of these batteries is challenging because of its complexity, low extraction efficiency, and high cost. Herein, we demonstrate a sustainable, green, and effective recovery process for rare earth metals while directly preparing LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathodes from cathode and anode AC-NiMH spent materials. Based on the different solubility of metal-salt, a stepwise leaching was proposed. We investigate the effects of a range of parameters (i.e., initial acid concentration, reaction temperature, and time) on the leaching process. Over 99% of rare earth, Co, Ni, and Mn are leached out during the recovery process, with the leaching kinetics following a shrinking core model with inter-diffusion as the rate-determining step. Rare earths are recovered in the form of high-purity sulfuric acid complex salts, while Ni, Co, and Mn are used to synthetize LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathodes with good electrochemical properties. This research demonstrates a sustainable process for the recycling of power sources.

The feeding of the broiler chickens on fodder with sulphate and Zink mixed ligand complex and their slaughter characteristics

The effectiveness of the use of sulfate and the mixed zinc ligand complex Zinc and the effect of their feeding on the slaughter indicators of broilers of the Cobb-500 cross were studied after the completion of scientific and economic experience and control slaughter conducted in the premises of the vivarium of the Bila Tserkva National Agricultural University. The difference in feeding conditions between the groups was that for the poultry of the first group, depending on age, compound feed was prepared using zinc sulfate in a dose corresponding to the introduction of 60, 50 and 40 g of element per 1 ton of feed (control), for the second - using a mixed zinc ligand complex at a dose that also corresponds to the introduction of 60, 50 and 40 g of element per 1 ton, and for the third - using a zinc mixed mixed ligand complex at a dose corresponding to the introduction of 45, 37.5 and 30 g. Zinc concentration in the mixed fodder decreased as the age of birds increased. The control slaughter, which has been carried out after the experiment, shows that the different dose use of Sulphate and Zinc mixed ligand complex differently influences on the slaughter characteristics of the control and experimental bird groups. Thus, the largest pre-slaughter weight (2649.3 g) of broiler chicks of the 3rd group is (p <0.01) if they consume mixed fodder with a mixed ligand complex of Zinc at doses corresponding to the adding of 45, 37.5 and 30 g of the element per 1 ton of mixed fodder. The pre-slaughter weight of the 2nd group, which has consumed mixed fodder with Zinc mixed ligand complex at a dose corresponding to adding 60, 50 and 40 g of the element per 1 ton of feed is also higher than in the control group (2549.3 g). But the probable difference for this index is not established. In general, the pre-slaughtered weight of the 2nd and 3rd group is higher than the weight of the the control group, respectively by 4.6 and 8.7 %. Regarding the mass of the gutted carcass, it was also greater in the birds of the 2nd and 3rd experimental groups, and the difference was significant. An analysis of the relative indicators of the yield of slaughter products showed that they were better in poultry that consumed compound feeds with a mixed zinc ligand complex. So, the output of a half-gutted carcass was the largest among broilers of the 3rd experimental group (84.19 %), and the difference in this indicator compared with the control was significant (p <0.05). Chickens of the 2nd and 3rd experimental groups showed a tendency to increase the output of the pectoral muscles, muscles of the limbs, skin, lungs and heart. The results of scientific and economic experience have shown that feeding compound feed with the mixed zinc ligand complex, in comparison with sulfate, can improve the slaughter quality and yield of edible carcasses. The relative index analysis of the slaughter products reveals that the poultry fed on Zinc mixed ligand complex, has better result. Thus, the yield of a semi-eviscerated carcass is the highest in broiler chicks of the experimental group № 3 (84.19 %), and the difference in this characteristics has been compared with the control group (p <0.05). There is an output increasing tendency of the thoracic muscles, limb muscles, skin, lung and heart in the 2nd and 3rd experimental group. But the probable difference of these indexes in the control and experimental groups has not been established, except for the heart output. Thus, it can be concluded that broiler chicks fed on fodder with Zinc mixed ligand complex, in comparison with Sulfate one, makes it possible to improve the slaughter characteristics and the yield of edible parts of the carcass, and the optimum dose is equivalent to 37.5 g of the element per 1 ton of the feed. Key words: broiler chickens, pre-slaughter weight, slaughter yield, carcass weight, mass of internal organs, Zinc mixed ligand complex, Zinc sulfate.

Development of Liposomal Gemcitabine with High Drug Loading Capacity.

Liposomes are widely used for systemic delivery of chemotherapeutic agents to reduce their nonspecific side effects. Gemcitabine (Gem) makes a great candidate for liposomal encapsulation due to the short half-life and nonspecific side effects; however, it has been difficult to achieve liposomal Gem with high drug loading capacity. Remote loading, which uses a transmembrane pH gradient to induce an influx of drug and locks the drug in the core as a sulfate complex, does not serve Gem as efficiently as doxorubicin (Dox) due to the low p Ka value of Gem. Existing studies have attempted to improve Gem loading capacity in liposomes by employing lipophilic Gem derivatives or creating a high-concentration gradient for active loading into the hydrophilic cores (small volume loading). In this study, we combine the remote loading approach and small volume loading or hypertonic loading, a new approach to induce the influx of Gem into the preformed liposomes by high osmotic pressure, to achieve a Gem loading capacity of 9.4-10.3 wt % in contrast to 0.14-3.8 wt % of the conventional methods. Liposomal Gem showed a good stability during storage, sustained-release over 120 h in vitro, enhanced cellular uptake, and improved cytotoxicity as compared to free Gem. Liposomal Gem showed a synergistic effect with liposomal Dox on Huh7 hepatocellular carcinoma cells. A mixture of liposomal Gem and liposomal Dox delivered both drugs to the tumor more efficiently than a free drug mixture and showed a relatively good anti-tumor effect in a xenograft model of hepatocellular carcinoma. This study shows that bioactive liposomal Gem with high drug loading capacity can be produced by remote loading combined with additional approaches to increase drug influx into the liposomes.

A Robust, Freestanding MXene‐Sulfur Conductive Paper for Long‐Lifetime Li–S Batteries

AbstractFreestanding, robust electrodes with high capacity and long lifetime are of critical importance to the development of advanced lithium–sulfur (Li–S) batteries for next‐generation electronics, whose potential applications are greatly limited by the lithium polysulfide (LiPS) shuttle effect. Solutions to this issue have mostly focused on the design of cathode hosts with a polar, sulfurphilic, conductive network, or the introduction of an extra layer to suppress LiPS shuttling, which either results in complex fabrication procedures or compromises the mechanical flexibility of the device. A robust Ti3C2Tx/S conductive paper combining the excellent conductivity, mechanical strength, and unique chemisorption of LiPSs from MXene nanosheets is reported. Importantly, repeated cycling initiates the in situ formation of a thick sulfate complex layer on the MXene surface, which acts as a protective membrane, effectively suppressing the shuttling of LiPSs and improving the utilization of sulfur. Consequently, the Ti3C2Tx/S paper exhibits a high capacity and an ultralow capacity decay rate of 0.014% after 1500 cycles, the lowest value reported for Li–S batteries to date. A robust prototype pouch cell and full cell of Ti3C2Tx/S paper // lithium foil and prelithiated germanium are also demonstrated. The preliminary results show that Ti3C2Tx/S paper holds great promise for future flexible and wearable electronics.

Ion exchange in complexing media – Nickel removal from ammoniacal ammonium sulfate solutions

In real hydrometallurgical systems, ion exchange of metal cations is often accompanied by competing processes, such as complex formation. In this paper, we have analyzed influence of complex formation on nickel uptake in a chelating ion exchanger that contains iminodiacetate groups. Both outer-sphere complexation with sulfate and inner-sphere complexation with ammonia were studied at 22 and 80 °C. In ammoniacal ammonium sulfate matrix, both these complexes are formed and prediction of nickel uptake becomes challenging. According to the results, nickel uptake can be substantially enhanced by complex formation. Under acidic conditions and at 80 °C, proton is complexed by sulfate more effectively than nickel and as a result, the exchange equilibrium favors nickel uptake. High sulfate background concentration further enhances the positive effect. In ammonium sulfate solutions, however, complexation with ammonia is needed to prevent nickel precipitation. The solution is stable near pH 7 and high nickel uptake can be obtained, because competition by H+ is practically absent and Ni2+/NH4+ selectivity is high. Complexation with NH3 thus makes the conditions favorable for Ni uptake rather than affects directly on Ni exchange. All these findings were successfully correlated with a dynamic model including pertinent complexation and dissociation equilibria.

Coinage Metal–Sulfur Complexes: Stability on Metal(111) Surfaces and in the Gas Phase

We provide a comprehensive theoretical assessment at the level of density functional theory (DFT) of the stability of various coinage metal–sulfur complexes, both in the gas phase and also for the complexes adsorbed on the (111) surface of the same coinage metal. Our primary interest lies in the latter where earlier scanning tunneling microscopy (STM) experiments were interpreted to suggest the existence of adsorbed S-decorated metal trimers, sometimes as a component of more complex adlayer structures. Recent STM studies at 5 K directly observed other isolated adsorbed metal–sulfur complexes. For these adsorbed species, we calculate various aspects of their energetics including a natural measure of stability corresponding to their formation energy from sulfur adsorbed on terraces and from metal atoms that are in thermal equilibrium with the substrate. From this perspective, our DFT analysis shows that all of Ag2S3, Ag3S3, and many larger complexes on Ag(111) are strongly stable, Cu2S3 is stable, and some larger complexes are marginally stable on Cu(111), but only Au4S4 on Au(111) is stable. Results are consistent with STM observations for Cu(111) and Ag(111) surfaces but appear to deviate slightly for Au(111). A systematic analysis relating stability in the gas phase with that of adsorbed species is achieved within the framework of Hess’s law. This analysis also unambiguously elucidates various energetic contributions to stability.

More crystal field theory in action: the metal-4-picoline (pic)-sulfate [M(pic)x]SO4 complexes (M= Fe, Co, Ni, Cu, Zn, and Cd).

Seven crystal structures of five first-row (Fe, Co, Ni, Cu, and Zn) and one second-row (Cd) transition metal-4-picoline (pic)-sulfate complexes of the form [M(pic)x]SO4 are reported. These complexes are catena-poly[[tetrakis(4-methylpyridine-κN)metal(II)]-μ-sulfato-κ2O:O'], [M(SO4)(C6H7N)4]n, where the metal/M is iron, cobalt, nickel, and cadmium, di-μ-sulfato-κ4O:O-bis[tris(4-methylpyridine-κN)copper(II)], [Cu2(SO4)2(C6H7N)6], catena-poly[[bis(4-methylpyridine-κN)zinc(II)]-μ-sulfato-κ2O:O'], [Zn(SO4)(C6H7N)2]n, and catena-poly[[tris(4-methylpyridine-κN)zinc(II)]-μ-sulfato-κ2O:O'], [Zn(SO4)(C6H7N)3]n. The Fe, Co, Ni, and Cd compounds are isomorphous, displaying polymeric crystal structures with infinite chains of MII ions adopting an octahedral N4O2 coordination environment that involves four picoline ligands and two bridging sulfate anions. The Cu compound features a dimeric crystal structure, with the CuII ions possessing square-pyramidal N3O2 coordination environments that contain three picoline ligands and two bridging sulfate anions. Zinc crystallizes in two forms, one exhibiting a polymeric crystal structure with infinite chains of ZnII ions adopting a tetrahedral N2O2 coordination containing two picoline ligands and two bridging sulfate anions, and the other exhibiting a polymeric crystal structure with infinite chains of ZnII ions adopting a trigonal bipyramidal N3O2 coordination containing three picoline ligands and two bridging sulfate anions. The structures are compared with the analogous pyridine complexes, and the observed coordination environments are examined in relation to crystal field theory.

Специфіка лікування деструктивних змін у верхівковому періодонті у хворих на туберкульоз легень

Introduction. The prevalence of a number of socially dangerous illnesses in Ukraine, including pulmonary tuberculosis, is quite high. Considerable groups of patients, in addition to anti-TB treatment, also require adequate dental care, taking into account the general somatic status.The aim of the study. To evaluate the effectiveness of the use of antibiotics in the endodontic treatment of destructive forms of apical periodontitis in patients with pulmonary forms of active tuberculosis.Materials and methods. An endodontic treatment of 23 teeth in 19 patients aged 21-39 years (30,6±5,7) with regard to destructive apical periodontitis has been performed. Therapeutic manipulations were carried out within the framework of the existing protocols. In addition to standard procedures, cotton swabs with 5% solution of kanamycin sulfate were introduced into the root canal to create the stores. In the control group aged 20 – 44 years (32,5±7,6) – 24 persons (25 teeth) with a similar dental pathology, treatment was carried out according to the standard scheme indicated in the protocol, an additional drug treatment of root canals with an antibiotic was not conducted. The control of long-term results was performed after 6 and 12 months according to clinical and radiological data.Study results and their discussion. The analysis of the immediate results confirmed the reduction in the number of complications requiring repeated endodontic interventions and other therapeutic care activities by 27% compared to the control group. According to digital dental radiography, the use of the complex of kanamycin sulfate + calcium-containing paste in endodontic treatment accelerates the processes of restoration of bone structures in the destruction zone and allows in 12 month period to restore periodontitis in 72.0% of cases.Conclusions. The inclusion of kanamycin sulfate in the protocol of endodontic treatment of destructive processes in apical periodontitis in patients with active forms of pulmonary tuberculosis improves the remote results due to the sanitation and prevention of the formation of specific infection centers in the maxillofacial area and activation of reparative processes.

Selective Separation of Radium and Actinium from Bulk Thorium Target Material

A complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material will be presented. The process may be applicable to the production of 225Ac and 227Ac via proton spallation on thorium targets. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Targeting the minor components (Ac,Ra) allows use of much smaller chromatographic columns than traditional nitrate based systems which target the bulk thorium. Additionally, the primary separation is performed from 0.1M Th, 0.6M sulfate, pH 1-2 instead of the more corrosive 3-8M HNO3 typically employed in solvent extraction or anion exchange based thorium separations. Actinium and radium are recovered from the cation exchange resin in a small volume of 5M HNO3 and directly purified via extraction chromatography with UTEVA and DGA resins without feed adjustment or evaporation. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity. The flowsheet has been tested at the Canadian Nuclear Laboratory (CNL) on 25 gram solid thorium targets irradiated at Fermi Lab. -Bond, A.H., Horwitz, E.P., McAlister, D.R., 2006. A Multicolumn Selectivity Inversion Generator for the Production of High Purity Actinium-225 for Use in Therapeutic Nuclear Medicine, United States patent number 7,087,206. (Licensed to NorthStar Medical Radioisotopes) -D.R. McAlister, E.P. Horwitz, “Selective Separation of Radium and Actinium from Bulk Thorium Target Material on Strong Acid Cation Exchange Resin from Sulfate Media,” Applied Radiation and Isotopes, 140, 18-23 (2018).

Investigating the role of the different metals in hydrotalcite Mg/Al-based adsorbents and their interaction with acidic sorbate species

The role of aluminum in the structure of hydrotalcite-based sorbents was investigated with 27Al-NMR and XPS with respect to the chemisorption mechanism of different sorbate species, such as CO2, H2O and H2S, at elevated temperatures. Sorbent materials with different ratios of Al/Mg were studied in order to elucidate the influence of the material composition on the Al coordination. Two different tetrahedrally and octahedrally coordinated Al species were detected. It was found that their quantitative appearance depends on the ratio of Al/Mg within the sorbent material. A higher Mg content leads to a higher distortion and to the formation of more tetrahedrally coordinated Al with a high chemical shift. Whereas CO2 and H2O adsorption does not seem to influence well-coordinated Al, as observed with NMR, chemisorption of H2S showed a clear interaction with Al leading to the formation of an additional tetrahedrally coordinated site with a high chemical shift. XPS showed that a reversible metal sulfate complex was formed on the sorbent, which was reversible upon exposure to H2O.

Gold passivation by sulfur species: A molecular picture

The role of sulfur species in the passivation of gold surface in cyanide and thiosulfate solutions was investigated using density functional theory (DFT). The interaction energy between various sulfur complexes as well as deposited sulfur allotropes with the gold surface were computed and the contribution of each specie to the formation of a passivated layer were compared. For this purpose, a new parameter was introduced to explain and understand the tendency of each sulfur complex to interact with the gold surface from a molecular point of view. It was observed that the ratio of the hydration to the binding energy (H/B) of each sulfur specie can be well correlated with the calculated interaction energy with the gold surface. This parameter could be effectively used to predict the interaction of each specie with a substance, only based on the structural characteristics of the specie. It has been also demonstrated that the theoretically calculated energies of interactions of sulfur complexes with the gold surface are well correlated with experimentally reported data. The results showed that S, S2−, polysulfides, tetrathionate, and sulfite species affect the gold leaching process directly through the passivation of the gold surface. Sulfate, dithionate, trithionate, and thiocyanate do not contribute to the passivation effect, although they indirectly affect the gold leaching process by consuming the oxygen and cyanide required to dissolve gold in the cyanidation process. The sulfur allotropes forming on the gold surface also passivate the gold surface and limit the access of the lixiviants required for the gold leaching process. The results could shed light on the mechanism of passivation of gold surface by sulfur species in gold leaching and this effect can be controlled by inhibiting the formation of main sulfur contributors in passivation process.

Efficacy and Tolerability of Progen, a Nutritional Supplement Based on Innovative Plasma Proteins, in ACL Reconstruction: A Multicenter Randomized Controlled Trial.

Background:New biologic strategies are arising to enhance healing and improve the clinical outcome of anterior cruciate ligament (ACL) reconstruction.Purpose:To evaluate the efficacy of a new oral nutritional supplement (Progen) that contains hydrolyzed collagen peptides and plasma proteins, a hyaluronic acid–chondroitin sulfate complex, and vitamin C.Study Design:Randomized controlled trial; Level of evidence, 2.Methods:The study included patients who underwent ACL reconstruction with hamstring autografts using the same fixation method. All patients received the same analgesia and physical therapy (PT) protocol and were randomized to receive either the nutritional supplement (supplemented group) or no additional therapy (control group). Patients were followed up at days 7, 30, 60, and 90. Pain was assessed by use of a visual analog scale (VAS) and by analgesic consumption. Clinical outcome was assessed via International Knee Documentation Committee (IKDC) score and the number of PT sessions. Perceived efficacy and tolerability were rated on a 5-point Likert scale. Graft maturation was assessed by a blinded musculoskeletal radiologist using magnetic resonance imaging. The number of adverse events (AEs) was recorded.Results:The intention-to-treat analysis included 72 patients, 36 allocated to the supplemented group and 36 to the control group, with no significant differences regarding demographic and preoperative characteristics. Both groups showed significant improvement in pain and function (measured by VAS and IKDC scores) during the 90-day follow-up period (P < .001 for both), without significant differences between groups. The supplemented group had fewer patients that needed analgesics (8.5% vs 50.0%; P < .05) and attended fewer PT sessions (38.0 vs 48.4 sessions; P < .001) at 90 days and had a higher IKDC score at 60 days (62.5 vs 55.5; P = .029) compared with the control group. Patient- and physician-perceived efficacy was considered significantly higher in the supplemented group at 60 and 90 days (P < .05). Perceived tolerability of the overall intervention was better in the supplemented group at 30, 60, and 90 days (P < .05). Graft maturation showed more advanced degrees (grades 3 and 4) in the supplemented group at 90 days (61.8% vs 38.2%; P < .01). No intolerance or AEs associated with the nutritional supplement treatment were reported.Conclusion:The combination of the nutritional supplement and PT after ACL reconstruction improved pain, clinical outcome, and graft maturation. Nutritional supplementation showed higher efficacy during the second month of recovery, without causing AEs.Registration:NCT03355651 (ClinicalTrials.gov identifier).

Diarylborinic Acid-Catalyzed, Site-Selective Sulfation of Carbohydrate Derivatives.

Sulfated carbohydrates have been implicated in diverse biological processes, with the position and extent of sulfation of a glycoside often playing important roles in determining the affinity and specificity of its binding to a biomolecular partner. Methods for the site-selective introduction of sulfate groups to carbohydrates are thus of interest. Here, we describe the development of a diarylborinic acid-catalyzed protocol for selective sulfation of pyranoside derivatives at the equatorial position of a cis-1,2-diol group. This method, which employs the sulfur trioxide-trimethylamine complex as the electrophile, has been employed for installation of a sulfate group at the 3-position of a range of galacto- and mannopyranosides, including substrates having a free primary OH group. By using a full equivalent of the diarylborinic acid, selective syntheses of more complex monosulfated glycosides, namely, a 3'-sulfolactose derivative and 3'-sulfo-β-galactosylceramide, have been accomplished. Preliminary kinetics experiments suggested that the catalyst resting state is a tetracoordinate diarylborinic ester that reacts with the SO3 complex in the turnover-limiting step. Catalyst inhibition by the pyranoside sulfate product and trialkylamine byproduct of the reaction was demonstrated.

Thermodynamic and structural aspects of the aqueous uranium(iv) system - hydrolysis vs. sulfate complexation.

The aquatic species of U(iv) in acidic aqueous solution in the presence of sulfate were studied in the micromolar range by a combined approach of optical spectroscopy (UV/vis and mid-IR), quantum-chemical calculations (QCC), and thermodynamic modelling. The number of species occurring in solution within the pH range 0-2 was assessed by decomposition and fitting of photometric spectra using HypSpec and Geochemist's Workbench software. Single component spectra of U4+, UOH3+, USO42+ and U(SO4)2 were obtained and extinction coefficients ελ were calculated to be 61.7, 19.2, 47.6 and 40.3 L mol-1 cm-1, respectively. Complex formation constants of two U(iv) sulfate species and the first hydrolysis species UOH3+ in infinitely diluted solution were determined by thermodynamic modelling to be log β = 6.9 ± 0.3, log β = 11.8 ± 0.5 and log β = -(0.36 ± 0.1), respectively. No further U(iv) sulfate and hydrolysis species were observed under the prevailing conditions. Molecular structural information of the sulfate species was derived from vibrational spectra and QCC exhibiting a predominant monodentate coordination of the sulfate ions.

Effects of Dietary Zinc Amino Acid Complex and Zinc Sulfate on Growth Performance, Digestive Enzyme Activity and Immune Response in Asian Seabass (Lates calcarifer)

Zinc is an essential trace mineral to fish and vital to various biological processes and function. The artificial diets offered to intensively cultivated fish must possess the zinc content required by the animal metabolism for health maintenance and high weight gain. However, essential elements must also be in an available form to be utilized by the organism. Thus, this study was designed to evaluate the effects of different zinc forms, including organic zinc (zinc amino acid complex) and inorganic zinc (zinc sulfate) as feed additives in diets on in vitro protein digestibility, growth performance, feed utilization, digestive enzyme activity, immune response and muscle quality of Asian seabass (Lates calcarifer). The study was assigned in CRD with 3 treatments and 3 replicates. Three groups of fish with mean weight 22.54 ± 0.80 g, were given a basal diet either unsupplemented (control) or supplemented with 50 mg Zn kg-1, as zinc sulfate (ZnSO4) or zinc amino acid complex (ZnAA). The fish were fed experimental diets 3.0% of their body weight per day, twice daily at 08.00 and 16.00 h, for 10 weeks. At the end of the experiment, no significant differences were observed on protein digestibility, survival, growth performance and feed utilization across the three dietary treatments (P>0.05). Fish fed ZnSO4 diets exhibited a significant increase in the specific activities of total protease, pepsin and trypsin compared with ZnAA and the control (P 0.05). The results of the present work allowed us to conclude that there was no difference in the growth between the two zinc sources but ZnAA supplementation exhibited a higher immunity response in Asian seabass.