Extraction Of Ag Research Articles

Non-Muscle Myosin II Is Essential for the Negative Regulation of B-Cell Receptor Signaling and B-Cell Activation.

Antigen (Ag)-triggered B-cell receptor (BCR) signaling initiates antibody responses. However, prolonged or uncontrolled BCR signaling is associated with the development of self-reactive B-cells and autoimmune diseases. We previously showed that actin-mediated B-cell contraction on Ag-presenting surfaces negatively regulates BCR signaling. Non-muscle myosin II (NMII), an actin motor, is involved in B-cell development and antibody responses by mediating B-cell migration, cytokinesis, and Ag extraction from Ag-presenting cells. However, whether and how NMII regulates humoral responses through BCR signaling remains elusive. Utilizing a B-cell-specific, partial NMIIA knockout (cIIAKO) mouse model and NMII inhibitors, this study examined the role of NMII in BCR signaling. Upon BCR binding to antibody-coated planar lipid bilayers (PLB), NMIIA was recruited to the B-cell contact membrane and formed a ring-like structure during B-cell contraction. NMII recruitment depended on phosphatidylinositol 5-phosphatase (SHIP1), an inhibitory signaling molecule. NMII inhibition by cIIAKO did not affect B-cell spreading on PLB but delayed B-cell contraction and altered BCR clustering. Surface BCR “cap” formation induced by soluble stimulation was enhanced in cIIAKO B-cells. Notably, NMII inhibition by cIIAKO and inhibitors up-regulated BCR signaling in response to both surface-associated and soluble stimulation, increasing phosphorylated tyrosine, CD79a, BLNK, and Erk and decreasing phosphorylated SHIP1. While cIIAKO did not affect B-cell development, the number of germinal center B-cells was significantly increased in unimmunized cIIAKO mice, compared to control mice. While cIIAKO mice mounted similar antibody responses when compared to control mice upon immunization, the percentages of high-affinity antibodies, Ag-specific germinal center B-cells and isotype switched B-cells were significantly lower in cIIAKO mice than in control mice. Furthermore, autoantibody levels were elevated in cIIAKO mice, compared to control mice. Collectively, our results reveal that NMII exerts a B-cell-intrinsic inhibition on BCR signaling by regulating B-cell membrane contraction and surface BCR clustering, which curtails the activation of non-specific and self-reactive B-cells.

Trihexyl(tetradecyl)phosphonium bis-2,4,4-(trimethylpentyl)phosphinate micellar behavior in the extraction of Ag(I) from acidic nitrate media

The distribution of Ag(I) between acidic aqueous phase (HNO3) and organic phases, composed of trihexyl(tetradecyl)phosphonium bis-(2,4,4-trimethylpentyl)phosphinate (Cyphos® IL 104) diluted in kerosene or kerosene/1-decanol, has been studied. In order to elucidate the interactions in solution and the chemical equilibria responsible for Ag(I) extraction by Cyphos® IL 104, ionic conductivity, dynamic viscosity, and interfacial tension measurements, determination of water and nitric acid extraction were performed, and the organic phases were characterized by infrared spectroscopy (ATR-FTIR). Ag(I) is extracted by Cyphos® IL 104 with high affinity, even under slightly acidic conditions (close to 100% at pH 5). The linear relationship between the logarithm of the distribution ratio of Ag(I) (D) and the logarithm of Cyphos® IL 104 concentration exhibits a slope greater than the stoichiometry expected (1:1), demonstrating an atypical extraction equilibrium. The change in the physicochemical properties as a function of Cyphos® IL 104 concentration permits to deduce the formation of reverse micelles or aggregates in organic phases at the critical micellar concentration CMC = 0.001 mol L-1. The ATR-FTIR characterization showed that Ag(I) was extracted by the phosphinate group of Cyphos® IL 104 with the transfer of water and nitric acid. A thorough analysis of these data indicates a similar mechanism to solvation, and the reverse micelles (or agglomerates) are involved in Ag(I) extraction.

Sorption of silver (I) ions from aqueous solutions using the synthetic sorbent

We study the sorption of silver ions from aqueous solutions by a synthetic chelating sorbent. In the presence of formaldehyde, a polymeric sorbent based on a copolymer of styrene with maleic anhydride, modified with N,N’-diphenylguanidine, was synthesized and further used for extracting Ag(I) ions. The composition and structure of the synthesized polymeric chelating sorbent were studied using IR and UV spectroscopy methods. A simple, inexpensive, and efficient method for extracting Ag(I) ions from aqueous solutions was used. The effect of various parameters on the sorption process was studied, including the acidity of the medium (pH), the initial concentration of the metal ion, the time required to establish complete sorption equilibrium, and ionic strength. The optimum pH value for the extraction of Ag(I) was found to be 6. The process is characterized by a high adsorption capacity reaching 547.2 mg/g. The research results showed that the time required to establish a complete sorption equilibrium for the sorbent modified with N,N’- diphenylguanidine is 60 min. Ag(I) adsorption increases up to the value of ionic strength of μ = 1, after which its intensity decreases. At the final stage, the process of desorption of absorbed silver ions was carried out. During desorption, the best eluting agent for the extraction of Ag(I) was determined to be 0.5 M HNO3. The sorbent can be re-used after regeneration. The copolymer of styrene and maleic anhydride modified with N,N’-diphenylguanidine has a high sorption capacity and, therefore, can be used as a potential adsorbent for the extraction of silver (I) from aqueous solutions.

An Autochthonous Acidithiobacillus ferrooxidans Metapopulation Exploited for Two-Step Pyrite Biooxidation Improves Au/Ag Particle Release from Mining Waste

Pyrite bio-oxidation by chemolithotrophic acidophile bacteria has been applied in the mining industry to bioleach metals or to remove pyritic sulfur from coal. In this process, it is desirable to use autochthonous and already adapted bacteria isolated directly from the mining sites where biomining will be applied. Bacteria present in the remnant solution from a mining company were identified through cloning techniques. For that purpose, we extracted total RNA and performed reverse transcription using a novel pair of primers designed from a small region of the 16S gene (V1–V3) that contains the greatest intraspecies diversity. After cloning, a high proportion of individuals of the strains ATCC-23270 (NR_074193.1 and NR_041888.1) and DQ321746.1 of the well-known species Acidithiobacillus ferrooxidans were found, as well as two new wild strains of A. ferrooxidans. This result showed that the acidic remnant solution comprises a metapopulation. We assayed these strains to produce bioferric flocculant to enhance the subsequent pyrite bio-oxidation, applying two-stage chemical–bacterial oxidation. It was shown that the strains were already adapted to a high concentration of endogenous Fe2+ (up to 20 g·L−1), increasing the volumetric productivity of the bioferric flocculant. Thus, no preadaptation of the community was required. We detected Au and Ag particles originally occluded in the old pyritic flotation tailings assayed, but the extraction of Au and Ag by cyanidation resulted in ca. 30.5% Au and 57.9% Ag.

Characterization of silver nano-particles synthesized using fenugreek leave extract and its antibacterial activity

In the present study silver nano-particles were synthesised by green synthesis method using fenugreek leaves extract, provides necessary bioactive for reduction of silver ions to silver nanoparticles. The sharp bands of silver nanoparticles were observed around 432 nm. Synthesis process was further optimized for pH, extraction temperature, Ag ion concentration, extract volume and extraction time on the basis of absorbance and average particles size respectively. FTIR analysis showed presence of corresponding peaks of O–H stretching and N–H amide groups. FESEM images revealed the structure and morphology of spherical AgNPs of average size 30 nm. The antibacterial activity of thus synthesized AgNPs was then tested against S. aureus, E. coli, P. aeruginosa and V. cholera and found synthesized AgNPs have higher inhibitory action against P. aeruginosa compared to other bacteria. The larger size of nano-particles is less active than smaller size of nano-particles due to small surface area.

Aster glehni F. Schmidt Extract Modulates the Activities of HMG-CoA Reductase and Fatty Acid Synthase.

Aster glehni F. Schmidt (AG), is a natural product known to have anti-obesity effects, but the mechanism underlying these effects is not well documented. We hypothesized that AG may have inhibitory effects on enzymes related to lipid accumulation. Herein, AG fractions were tested against HMG-CoA reductase (HMGR) and fatty acid synthase (FAS), two important enzymes involved in cholesterol and fatty acid synthesis, respectively. We found that dicaffeoylquinic acid (DCQA) methyl esters present in AG are largely responsible for the inhibition of HMGR and FAS. Since free DCQA is a major form present in AG, we demonstrated that a simple methylation of the AG extract could increase the overall inhibitory effects against those enzymes. Through this simple process, we were able to increase the inhibitory effect by 150%. We believe that our processed AG effectively modulates the HMGR and FAS activities, providing promising therapeutic potential for cholesterol- and lipid-lowering effects.

A magnetic nanocomposite based on amine-functionalized pH-sensitive functional poly(styrene-co-maleic anhydride) copolymer for selective extraction, pre-concentration and determination of sub-trace Ag+ and Cu2+ ions from edible vegetable oils by a combination of spectrophotometry and ultrasound-assisted cloud point extraction

A magnetic nanocomposite based on amine-functionalized pH-sensitive functional poly(styrene-co-maleic anhydride) copolymer for selective extraction, pre-concentration and determination of sub-trace Ag+ and Cu2+ ions from edible vegetable oils by a combination of spectrophotometry and ultrasound-assisted cloud point extraction

Recovery of Copper(II) and Silver(I) from Nitrate Leaching Solution of Industrial Dust via Solvent Extraction with LIX63

A nitrate leachate containing Cu(II), Ag(I), Ni(II), Mg(II), and Al(III) was obtained during the leaching of industrial dust, which arises during the pyrometallurgy of spent camera modules. To separate and recover Cu(II) and Ag(I) from the leaching solution, solvent extraction experiments using 5,8-diethyl-7-hydroxydodecan-6-oxime (LIX63) were conducted. LIX63 was found to selectively extract Cu(II) and Ag(I) over other metal ions (Ni(II), Mg(II), and Al(III)) at low nitric acid concentrations. The extraction efficiency of Cu(II) was more affected than that of Ag(I) by the acidity of the feed solution and the LIX63 concentration in the organic phase. Cu(II) and Ag(I) were simultaneously extracted using 2 mol/L LIX63. Cu(II) was separated from the loaded LIX63 via stripping with 4 mol/L HNO3, whereas Ag(I) was recovered via stripping with 0.1 mol/L thiourea after the removal of Cu(II). McCabe–Thiele diagrams for the extraction and stripping of Cu(II) and Ag(I) were constructed. The complete extraction of Cu(II) and Ag(I) was confirmed via counter-current extraction. Moreover, stripping simulation tests confirmed that higher than 99.99% of Cu(II) and 99.2% of Ag(I) were stripped. The purities of Cu(II) and Ag(I) in the recovered solution were 95.2% and 99.993%, respectively. A process flow chart for the recovery of Cu(II) and Ag(I) from the nitrate leachate of the target industrial dust was also provided.

Controlled Growth of Hierarchical Bi2Se3/CdSe‐Au Nanorods with Optimized Photothermal Conversion and Demonstrations in Photothermal Therapy

AbstractIntegrating multiple mechanisms to maximize photothermal conversion efficiency is a significant strategy but remains challenging to construct therapeutic agents toward photothermal tumor treatment. Here, an approach to synthesize asymmetric Bi2Se3/CdSe‐Au hierarchical nanorods with excellent photothermal conversion is reported. Ag wetting‐layer is firstly grown to help overcome the interfacial lattice mismatch and promote the site‐selective growth of AgCdSe onto one end or side surface of Au nanorods. Subsequently, extraction of Ag+ ions out of lattice is observed during cation exchange reaction and epitaxial growth of Bi2Se3 shell. Bi2Se3/CdSe heterojunction with type‐II band alignment is formed and located at the plasmonic hotspots of Au nanorods, which experiences enhanced light absorption and accelerates the charge separation of photo‐excited carriers. Under excitation of near‐infrared 808 nm laser, the matchstick‐like Bi2Se3/CdSe‐Au nanorods show an excellent photothermal conversion, with 4.3 times temperature increment (ΔT) than that of bare Au nanorods. Moreover, in vitro and in vivo experiments verify them as excellent photothermal therapeutic agents.

Extraction of valuable metals from discarded AMOLED displays in smartphones using Bacillus foraminis as an alkali-tolerant strain.

With the alarming rate of e-waste generation, resource recovery from secondary metal sources is essential for sustainable resource utilization and to prevent the release of potentially toxic elements into the environment. In the current study, the first-time extraction of Ag, Mo, and Cu from active-matrix organic light-emitting diode (AMOLED) screens of discarded smartphones have been achieved using organic acids produced by Bacillus foraminis cultured on a modified Horikoshi medium. The influences of initial pH, inoculation size, and pulp density on the bioleaching process were evaluated over six-day experiment. Maximum extraction of Ag, Mo, and Cu (100, 56.8, and 41.4%) at optimal values of three investigated factors was obtained over a 12-day bioleaching experiment. A diverse assemblage of organic acid was produced in the optimized bioleaching condition, including tartaric (12.1mM), formic (49.8mM), acetic (21.5mM), lactic (78.5mM), citric (2.7mM), and propionic (69.6mM) acid. The contact angle analysis highlighted more hydrophobicity of powder after the bioleaching. FTIR and CHNO data also confirmed the role of bioleaching in the powder wettability alteration. The sequential extraction method revealed high mobility of In, Fe, Co, Cu, Cr, and Mo and low mobility of Ag. The results exhibited high tolerance of alkali-tolerant bacteria to potentially toxic elements and its superior performance in the bioleaching of discarded mobile screens at high pulp density.

Environmental-friendly synthesis of Au-Ag alloy nanoparticles using Anethum graveolens leaf extract and their application to Surface Enhanced Raman Scattering (SERS)

We report an Environmental-friendly method for the synthesis of Au-Ag alloy nanoparticles (ANPs) by using Anethum graveolens fresh leaf extract as a reducing and stabilizing agent. The precursor solutions of Au (HAuCl4: 3H2O), Ag (AgNO3) and leaf extract were mixed by varying molar ratios and heated with continuous stirring at 70℃ for an hour leads a formation of Au-Ag ANPs with different atomic compositions. The periodic observation of colour changes indicated the formation of Au-Ag ANPs and got confirmed by the measurement of UV-Vis spectroscopy. The synthesized Au-Ag ANPs were characterized for morphological and elemental composition using Transmission Electron Microscopy (TEM) in conventional and scanning TEM (STEM) mode. The TEM image analysis shows that the synthesized Au-Ag ANPs were found to be in spherical shape with a broad size distribution with a mean size of 23 ± 18 nm. The energy dispersive X-ray (EDX) spectrometry in the STEM mode confirms the formation of Au-Ag ANPs . To show that these biosynthesized Au-Ag ANPs can be used as SERS (Surface Enhanced Raman Scattering) substrates, we carried out SERS studies using Crystal Violet (CV) and Rhodamine 6G (R6G) as test molecules by using 514.5 nm laser excitation wavelength. The detection level achieved was 50µM of CV and R6G, which would lead to exploring biosensing applications.

Neutral organophosphorus ligands as a molecular lab for simultaneous detecting of Ag(I) ions

Study of the liquid-liquid extraction of Ag(I) ions with a series of phosphine oxides (trioctylphosphine, tributylphosphine, triphenylphosphine, and octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide) and phosphorus-containing calix[4]arene by the well-known method of slope analysis and determination of the process parameters are presented employing CHCl3 and an ionic liquid, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C1C4im+][Tf2N−]) as diluents. The ligand effect on the complexation properties of Ag(I) is quantitatively assessed. The silver-containing extracts are examined by 1H, 31P NMR as well as by SEM and TEM approaches in order to viewing the cation coordination and ligands’ binding mode inside, in the organic phase solution at micro-scale level. A conclusion can be made about aggregation in micelle formation of the calix[4]arene under study upon extraction of Ag(I) ion. A method employing thermogravimetric analysis (TGA) is also exploited for the determination of the solubility of CMPO ligand diluted in [C1C4im+][Tf2N−]. Final conclusions are given highlighting the role of the diluent, molecular or ionic, in complexation processes and selectivity involving ligands with P=O donor group and various metal s-, p-, d- and f-cations. The Ag(I) ions have shown the best extraction behavior compared to the other ions in the +1 oxidation state. Indeed, the calix[4]arene derivative bearing four P=O functions at the lower rim, shows strongly enhanced extraction as well as pronounced separation abilities towards lanthanoids in an ionic liquid environment.

The Effect of Anethum Graveolens L. (Dill) on Lipid Profile in Adults with Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Controlled Clinical Trials

Background: Several randomized clinical trials (RCTs) has assessed the effect of Anethum graveolens L. (AG) or dill supplementation on lipid profile in adults with cardiovascular risk factors with different results. Therefore, we decided to conduct a systematic review and meta-analysis regarding the available randomized controlled trials to assess AG supplementation's efficacy on lipid profile in adults with cardiovascular risk factors.
 Methods: PubMed, Embase, Cochrane's database, Ovid, Web of Science, ProQuest, Scopus, and Google Scholar were searched to find relevant articles investigating the effect of AG on the lipid profile of adults with risk factors for cardiovascular disease up to December 2020. Six trials with seven treatment armsmet the inclusion criteria. A random-effects model was used in the meta-analysis. To test heterogeneity, I2 statistics and Cochrane Q test were applied.
 Results: The results reported a significant improving effect of AG on TG [WMD = -29.20, 95% confidence interval (CI): -34.73,-23.68 mg/dL, p < 0.001], TC (WMD = -16.46, 95%CI: -21.54,-11.39 mg/dL, p < 0.001), LDL-C (WMD = -13.90, 95%CI: -16.08, -11.72 mg/dL, p < 0.001), and HDL-C (WMD = 4.01, 95%CI: 3.48, 4.54 mg/dL, p < 0.001).
 Conclusion: This meta-analysis of randomized controlled clinical trials revealed that consuming AG extract for more than six weeks might improve lipid profile in adults with cardiovascular risk factors.

The untapped industrial crop, Cucumeropsis mannii: dry oil extraction, characterization and potential use as biodiesel feedstock and heavy metal sink

Due to the quest to meet a basic need – food, vast potentials of numerous African crops have remained unexplored. Cucumeropsis mannii, an invaluable West African melon, is cultivated for its edible proteinous oil-rich seeds. Here, we report for the first time, its potential use for biodiesel production over an uncommon heterogeneous nanocatalyst, and for wastewater treatment. An identification of the untapped species’ seed was made, for disambiguation. Oil (CMO) was expressed from the C. mannii seeds (CMS) and characterized. The CMS was found composed of 53.5% lipids, while 46.1% of the full-fat CMS flour was recovered as vegetable oil. Transesterification experiments were performed using a specially-prepared heterogeneous nanocatalyst derived from Eobania vermiculata shells, by varying successively: methanol/oil ratio, temperature, and reaction time. Maximum biodiesel (CMOME) yield of 86.2% was achieved at catalyst concentration of 5.4%, methanol to oil molar ratio of 9:1, reaction temperature of 60 °C, after 3 h of reaction. Furthermore, part of the polyunsaturated CMO was sulphur-functionalized and utilized at different dosage levels for extraction of Ag+ from 600 to 1500 ppm simulated water. The modified CMO exhibited desirable sorption properties – sinking 100% of Ag+ from 900 ppm water, after 7-h-phase-contact at 6.9 g (20 mL)− 1 dosage. Stagewise operation (multi-staging) was found capable of improving the extraction efficiency in highly concentrated wastewater. Although CMOME conformed to EN-14214 and ASTM D-6751 standards, it had low oxidation stability; making wastewater treatment a more faithful application. Regarding the crop’s food value, residual CMS cake remained edible, even with longer shelf-life (relative to the full-fat flour) – encouraging commercial flour-defattening and consequent availability of CMO for industrial applications. Lastly, it was concluded (with some relevant recommendations) that CMO has great potentials for use as biodiesel feedstock and as heavy metal removal agent.

The Ameliorative Role of Acacia senegal Gum against the Oxidative Stress and Genotoxicity Induced by the Radiographic Contrast Medium (Ioxitalamate) in Albino Rats.

Arabic gum (Acacia senegal, AG) is proven effective antioxidant and cytoprotective agent. The present study was designed to test this notion by investigating the possible role of AG against the radiographic contrast medium (Ioxitalamate, Telebrix-35®, TBX)-induced oxidative stress and genotoxicity. Albino rats were divided into four groups and supplied with either; distilled water, daily 10% (w/v) AG, an intravenous dose of TBX (1600 mg I/kg b.wt) and co-administration of TBX and AG. Rats were sacrificed and blood samples were collected to assess the genotoxicity employing the peripheral blood leucocytes fluorescent double staining; namely the acridine orange/ethidium bromide (AO/EB) staining and alkaline comet assay. Further, chromosomal analyses were done in bone marrow cells. Serum urea and creatinine levels, in addition to malondialdehyde (MDA), nitric oxide (NO), catalase (CAT) and glutathione (GSH) levels in kidney tissues were measured. Liquid chromatography-mass spectrophotometry (LC-MS-MS) was performed to identify the chemical composition of AG extract. Kidney functions, single/double-stranded DNA damage, chromosomal aberrations, mitotic index, MDA and NO levels were significantly (p < 0.001) increased in TBX-treated group compared to the control and AG-treated one. Meanwhile, CAT and GSH activities were significantly diminished and the AG supplementation significantly (p < 0.001) ameliorated these effects compared with the control and AG-treated groups. Five compounds have been identified using GNPS networking including 7,3′,4′-Trihydroxyisoflavone, Noscapine, Tetrahydropapaveroline, Costunolide, Hesperidin. In conclusion, results of the present study suggest that AG exerted a protective role against TBX-induced oxidative stress and genotoxicity which may be attributed to the active metabolites in the gum.

Sampling and combined Pb and Ag isotopic analysis of ancient silver coins and ores

The combination of Pb and Ag isotopes in silver coins, artefacts, and ores greatly helps identifying ancient metal sources and detecting alteration such as lead addition, ore mixing, and metal recycling. The present study proposes a new set of procedures suitable for high-precision analysis of lead and silver isotopes in Ag-bearing ores and ancient silver coins. The protocols for combined Pb and Ag extraction and purification are based on multi-step ion-exchange and reversed-phase partition chromatography. In addition to conventional drilling, which irreversibly damages the silver object being sampled, a new method was developed to collect metal from silver coins by etching their edges with a solution of hydrogen peroxide and ammonia (H2O2 + NH4OH), either pure or with added dispersed silicon carbide (SiC) to increase etching efficiency, a technique that only damages the coin patina. This technique can also be applied to silver artefacts other than coins with minor modifications to adapt to different object shapes. Multi-collection inductively-coupled plasma mass spectrometry (MC-ICP-MS) was used to measure the isotopic compositions of both Pb and Ag in ores and coins. Variations in Pb and Ag isotopic compositions are uncorrelated for all the material analyzed, whether ores or silver coins, which demonstrate that isotope variability results from physically different processes. Evidence of mixing between different components is observed for ores, while etched and drilled coins show a conspicuous range of Pb and Ag isotopic compositions. The latter is interpreted as resulting from mass-dependent fractionation during surficial alteration under oxidizing burial conditions, and from patina formation. Silver in patina is isotopically light due to the formation of Ag2S, while the layer below the patina is isotopically heavy. Preliminary patina removal followed by H2O2 + NH4OH etching with suspended SiC may be used as an alternative to coin drilling when the latter is not possible such as for rare and precious coins. The present techniques will further help distinguish primary Pb isotopic variability in artefacts and coins from secondary variations due to underground interaction with the water table, weathering from prolonged burial, and curatorial handling.

Identification of Chemical Compounds from Artemisia gmelinii using UPLC-QTOF-MS/MS and their Regulatory Effects on Immune Responses in DSS-Induced Colitis Mice.

Artemisia gmelinii Web. ex Stechm. (AG), a popular medicinal herb in Asia, has been used as a common food ingredient in Korea and is traditionally known for its anti-inflammatory properties. Therefore, in this study, we aimed to investigate whether AG relieves IBD, a classic chronic inflammatory disease of the gastrointestinal tract. We identified 35 chemical compounds in AG ethanol extract using ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry. In mice with DSS-induced IBD, AG administration attenuated the disease activity index and the serum and colonic levels of inflammatory cytokines and chemokines. AG treatment decreased nuclear factor-[Formula: see text]B (NF-[Formula: see text]B) signaling, a key mediator of inflammation, in the mouse colons. Additionally, AG extract enhanced immune responses in lymphoid tissues such as spleen and Peyer's patches. Thus, AG consumption potently ameliorated IBD symptoms and improved immune signaling in lymphoid tissues.

Surface processes at a polymetallic (Mn-Fe-Pb) sulfide subject to cyanide leaching under sonication conditions and with an alkaline pretreatment: Understanding differences in silver extraction with X-ray photoelectron spectroscopy (XPS)

Leaching of polymetallic sulfides is often challenging due to the complexity of these systems. The main issues are related to the formation of surface by-products or to the presence of different metals that require a greater consumption of chemicals compared to that needed to extract the target metal during leaching. This latter case is followed in the present work using X-ray photoelectron spectroscopy (XPS) during the leaching of a silver-containing polymetallic (Mn-Fe-Pb) sulfide under three different cyanidation procedures: (1) conventional leaching, (2) ultrasound-assisted leaching, and (3) leaching of a sample pretreated in alkaline media. In all cases, leaching results in the build-up of Pb compounds (oxides/hydroxides) on the surface of the minerals, suggesting a mechanism in which Pb is first leached by hydroxide and cyanide and later is re-adsorbed as an external layer on the minerals. On the other hand, the effect of each process on Mn was quite distinct: 1) Conventional leaching leads to the oxidation of the sulfide (pyrite) surface and a slight increase of surface Mn species; 2) Ultrasound-assisted leaching decreases surface Mn by dissolving oxidized species, which exposes fresh sulfide surfaces and increases Ag extraction; and 3) An alkaline pretreatment at high temperature exposed fresh sulfide surfaces and decreased the surface concentration of Mn. The fact that ultrasound-assisted leaching and leaching after an alkaline pretreatment allow for a higher Ag extraction (60% and 75% of total Ag, respectively, as opposed to the 25% extracted via conventional leaching), indicates that leaching is more efficient if the surface is not oxidized and if Mn is removed from the samples, either before or during leaching.

Designing New Antibacterial Wound Dressings: Development of a Dual Layer Cotton Material Coated with Poly(Vinyl Alcohol)_Chitosan Nanofibers Incorporating Agrimonia eupatoria L. Extract

Wounds display particular vulnerability to microbial invasion and infections by pathogenic bacteria. Therefore, to reduce the risk of wound infections, researchers have expended considerable energy on developing advanced therapeutic dressings, such as electrospun membranes containing antimicrobial agents. Among the most used antimicrobial agents, medicinal plant extracts demonstrate considerable potential for clinical use, due primarily to their efficacy allied to relatively low incidence of adverse side-effects. In this context, the present work aimed to develop a unique dual-layer composite material with enhanced antibacterial activity derived from a coating layer of Poly(vinyl alcohol) (PVA) and Chitosan (CS) containing Agrimonia eupatoria L. (AG). This novel material has properties that facilitate it being electrospun above a conventional cotton gauze bandage pre-treated with 2,2,6,6-tetramethylpiperidinyl-1-oxy free radical (TEMPO). The produced dual-layer composite material demonstrated features attractive in production of wound dressings, specifically, wettability, porosity, and swelling capacity. Moreover, antibacterial assays showed that AG-incorporated into PVA_CS’s coating layer could effectively inhibit Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) growth. Equally important, the cytotoxic profile of the dual-layer material in normal human dermal fibroblast (NHDF) cells demonstrated biocompatibility. In summary, these data provide initial confidence that the TEMPO-oxidized cotton/PVA_CS dressing material containing AG extract demonstrates adequate mechanical attributes for use as a wound dressing and represents a promising approach to prevention of bacterial wound contamination.

Ag removal from e-waste using supercritical fluid: improving efficiency and selectivity

ABSTRACT E-waste, including toxic and precious metals, requires an effective and environment-friendly disposal method. Extraction by supercritical CO2 is attractive, being inexpensive, available, and environment-friendly. This paper reports an investigation of Ag extraction from waste printed circuit boards [WPCBs] using supercritical CO2. Effects of temperature, pressure, dynamic time, various co-solvents, modifiers, and complex formers on the efficiency of the process are studied. The optimum reaction parameters are calculated through Response Surface Methodology (RSM). In addition, both calculated and experimental results are analysed using Design Expert software program, and the mathematical equations are presented for different parameters and experimental conditions. The optimum conditions for supercritical extraction are 217 bar, 51 ᵒC, and 40 mins, and the most appropriate ligand and co-solvent are found to be Cyanex 302 and acetone. Finally, a 98.75 Ag extraction from waste printed circuit boards was achieved using the proposed method.