Ag Content Research Articles

The optimization of poly(vinyl)-alcohol-alginate beads with a slow-release compound for the aerobic cometabolism of chlorinated aliphatic hydrocarbons.

Chlorinated aliphatic hydrocarbons (CAHs), such as cis-1,2-dichloroethylene (cDCE), are prevalent in groundwater at many locations throughout the United States. When immobilized in hydrogel beads with slow-release compounds, the bacteria strain Rhodococcus rhodochrous ATCC 21198 can be used for the in situ bioremediation of cDCE. These hydrogel beads must exhibit high mechanical strength and resist degradation to extend the lifetime of slow-release compounds and bioremediation. We engineered poly(vinyl)-alcohol - alginate (PVA-AG) beads to immobilize ATCC 21198 with the slow-release compound, tetrabutoxysilane (TBOS) that produces 1-butanol as a growth substrate, for high mechanical strength. We optimized three inputs (concentration of PVA, concentration of AG, and the crosslinking time) on two responses (compressive modulus and rate of oxygen utilization) for batch incubation experiments between 1 and 30 days using a design of experiments approach. The predictive models generated from design of experiments were then tested by measuring the compressive strength, oxygen utilization, and abiotic rates of hydrolysis for a predicted optimal bead formulation. The result of this study generated a hydrogel bead with immobilized R. rhodochrous ATCC 21198 and TBOS that exhibited a high compressive modulus on day 1 and day 30, which was accurately predicted by models. These hydrogel beads exhibited low metabolic activity based on oxygen rates on day 1 and day 30 but were not accurately predicted by the models. In addition, the ratio between oxygen utilization and abiotic rates of hydrolysis were observed to be roughly half of what was expected stoichiometrically. Lastly, we demonstrated the capability to use these beads as a bioremediation technology for cDCE as we found that, for all bead formulations, cDCE was significantly reduced after 30 days. Altogether, this work demonstrates the capability to capture and enhance the material properties of the complex hydrogel beads with predictive models yet signals the need for more robust methods to understand the metabolic activity that occurs in the hydrogel beads.

Spectroscopic analysis of nanosized Zn(Ag, Ni)O systems and observation of superparamagnetism at low temperature.

To understand the impact of binary doping in ZnO, nanosized Zn(Ag, Ni)O systems were synthesized by the sol-gel method. The amount of Ag was fixed at 2 at%, and that of Ni was varied from 1 to 15 at%. Ni incorporation equal to or beyond 3 at% gave rise to the development of the NiO phase. The presence of Ag and Ni did not have much influence on the lattice constants of ZnO. However, a larger addition of Ni impacted the unit cell of NiO, as indicated by the reduction of the lattice constant of NiO. The increase in NiO and Ag contents in ZnO reduced the second and third harmonic intensities under non-linear investigations. X-ray photoelectron spectroscopy analysis indicated that initial Ni addition varied randomly along with Ag, and it stabilized itself at higher concentration. Field emission scanning electron microscopy revealed that interlinked particles and chains with tamarind shapes were formed, closely matching the rod-like structures under high resolution. Ag and Ni addition altered the structures slightly and randomly till 5 at% Ni; thereafter they deviated from the particle shape to flat disc-shapes. Interestingly, the magnetic response of the sample was determined by the NiO phase, and the effect of Ni and Ag substitution in the ZnO host matrix was almost irrelevant at low temperatures toward magnetic contribution. Weak ferromagnetism at low temperatures (≤50 K) with superparamagnetic-like behavior (cusp in ZFC magnetization) was observed in all the samples. This could be attributed to the finite nano-size effect and uncompensated spins at the surface of the particle.

Multigenerational exposure of Ag materials (nano and salt) in soil - environmental hazards in Enchytraeus crypticus (Oligochaeta).

Because of its properties, silver is among the most used metals both as salt and as nanomaterials (NMs), hence reaching the environment. Multigenerational (MG) exposure testing is scarce, and especially so for NMs and soil invertebrates. In this study the MG effects of Ag NMs (Ag NM300K) and Ag salt (AgNO3) were assessed, using Enchytraeus crypticus in LUFA 2.2 soil. Survival, reproduction and internal Ag concentration in the animals were measured throughout 7 generations (5 generations (F0-F4) in spiked soil plus 2 (F5-F6) in clean soil) exposed to sublethal concentrations corresponding to the reproduction EC10 and EC50 obtained in standard toxicity tests (45 and 60 mg Ag per kg soil DW for AgNO3; 20 and 60 mg Ag per kg soil DW for Ag NM300K). MG exposure caused a dose-related decrease in reproduction for both Ag forms. Ag uptake peaked in the F1 (64 days) for AgNO3 and F2 (96 days) for Ag NM300K, after which it decreased. In agreement with toxicokinetic studies, a maximum body Ag concentration was reached (20 mg Ag per kg body DW (AgNO3) and 70 mg Ag per kg body DW (Ag NM300K)) and after which detoxification mechanisms seem to be activated with elimination of Ag accompanied by a decrease in reproduction. Transfer to clean soil allowed Ag to be (fully) eliminated from the animals. This MG study confirmed the effects determined in standard reproduction toxicity tests but further allowed to monitor the dynamics between exposure and effects of the Ag materials, and how the animals seem to cope with Ag for 7 generations by compensating between detoxification and reproductive output.

Decellularization of caprine forestomach rumen tissue modified with silver nanowires as an antibacterial skin substitute scaffold in wound care therapeutics.

In this study, caprine forestomach native collagen (CFNC) isolated from rumen tissues is reported for the first time with subsequent surface modifications with varying concentrations of silver nanowires (AgNWs). Accordingly, CFNC/AgNWs scaffolds were prepared to be used as suitable wound healing dressing materials through a sequential isolation and decellularization process, followed by step-wise AgNW surface modification and ultraviolet (UV) crosslinking. The significant outcomes of this research highlight that CFNC/AgNWs scaffolds exhibit a highly porous three-dimensional (3D) network structure with favourable physicochemical characteristics. Also, the comprehensive tensile testing demonstrated that there were changes in mechanical properties based on the AgNW content. The CFNC/AgNWs scaffolds also exhibited strong antibacterial action against E. coli and S. aureus in a dose-dependent manner. The release of Ag+ ions from CFNC/AgNWs scaffolds exhibited a slow and sustained release pattern over an extended period of time. The cell-biomaterial interaction studies on CFNC/AgNWs scaffolds using L929 fibroblast cells showed dose-dependent and time-dependent toxicity when the concentration exceeded above 1 mg mL-1. The cytotoxicity is mainly due to the higher concentration of Ag+ ions which initiates cell death through lipid peroxidation and causes cell membrane damage. The biocompatibility test results serve as a reference point to select the optimal dosage of AgNWs with balanced antibacterial and biocompatibility properties. Thus, the developed CFNC/AgNWs scaffolds will serve as a versatile wound dressing material similar to other metallic or conjugated reconstituted collagen systems with the added benefit of strong antimicrobial properties, and as a biomimetic xenograft for skin regeneration.

Potassium Amyl Xanthate (PAX) as an alternative organic reactive for mercury removal from cyanidation process of amalgamation tailing.

Mercury is the heavy metal that is most difficult to remove from cyanide solution. This situation brings with it many environmental, health and economic problems. This study aims to effectively utilize xanthate by presenting a new strategy for purifying mercury in the cyanidation process of amalgamation residues. In the study, the removal of mercury by precipitation using PAX from cyanidation leach solutions of a well-characterized amalgamation residue was investigated. The dosage of the precipitation reagent is the most important parameter in the removal of mercury. The mercury removal efficiency increases with the increase in the PAX/Hg ratio, and when the removal ratio is 60, the precipitation efficiency reaches a value of 66.7%. Applying coagulation and flocculation procedures after the precipitation process increases the mercury removal efficiency. It is seen that with this application, mercury can be removed with an efficiency of 95.6% at the same reagent rate. With this application, the particle sizes of the precipitates are enlarged and their filtration properties are improved. It has also been determined that the precipitates formed are in the form of HgS, a stable mercury compound. These results indicate that mercury can be effectively removed in its steady state. It was found that the concentration of Au and Cu did not change significantly, while the concentration of Ag decreased during the precipitation processes.

All-optical switching based on spatial self-phase modulation of Ag/violet phosphorus heterojunctions.

With the increasing demand for high-performance passive nonlinear photonic devices, significant progress has been made in spatial self-phase modulation (SSPM) based on 2D nanomaterials in all-optical switches, logic gates, and information converters in recent years. However, there are still challenges in improving the responsiveness of photonic devices. In this work, we prepared a heterojunction of Ag nanoparticles deposited on the surface of violet phosphorus nanosheets (VP Ns), investigated their SSPM, and demonstrated their performance in all-optical switches. The SSPM experimental results show that compared with pure VP Ns at the same light intensity, both the maximum number and the formation time of self-diffraction rings in Ag/VP heterojunctions increase, and the nonlinear refractive index is approximately doubled. The main reason for optical nonlinearity enhancement is that the internal electric field in the heterojunction strengthens the mobility of the photogenerated carrier, thereby enhancing its optical nonlinearity. In particular, we demonstrate the performance of all-optical switches based on SSPM by utilizing the superior optical nonlinearity of Ag/VP heterojunctions. It is shown that with the increase of low-dose Ag content in heterojunctions, the switching time in the all-optical switch becomes shorter and the maximum number of self-diffraction rings of the signal light increases, although the quality of self-diffraction rings slightly decreases due to the scattering of Ag particles. The results contribute to the design and implementation of high-performance nonlinear photonic devices, based on the use of heterojunctions with low-cost preparation and a high nonlinear refractive index.

Multilayer immobilizing of denitrifying Bacillus sp. and TiO2-AgNPs on floating expanded clay carrier for co-treatment of nitrite and pathogens in aquaculture.

Nitrite contamination and the spread of pathogens can seriously degrade water quality. To simultaneously control these factors, an innovative approach of fabricating a remediation agent that contained denitrifying bacteria and TiO2-AgNPs co-immobilized on floating expanded clay (EC) was proposed in this study. The EC was fabricated from a mixture of clay and rice husk through pyrolysis at a high temperature of 1200 °C, followed by a rapid cooling step to create a porous structure for the material. TiO2NPs were modified with Ag to shift the absorbance threshold of TiO2-AgNPs into the visible region of 700-800 nm. The experimental results showed that the stirring speed of 250 rpm was suitable for immobilizing TiO2-AgNPs on EC and achieved the highest Ti and Ag content of 639.38 ± 3.04 and 200.51 ± 3.71 ppm, respectively. Coating TiO2-Ag/EC with chitosan (0.5%) significantly reduced the detachment level of immobilized TiO2-AgNPs compared to that of the material with no coating. In particular, this functionalized material inhibited 99.93 ± 0.1% of Vibrio parahaemolyticus pathogen but did not adversely affect the denitrifying bacteria after 2 h of visible light irradiation. Based on the electrostatic bond between oppositely charged polymers, the denitrifying bacteria, Bacillus sp., in alginate solution was successfully immobilized on the chitosan-coated TiO2-Ag/EC with a bacteria density of (76.67 ± 9.43) × 107 CFU g-1, retaining its nitrite removal efficiency at 99.0 ± 0.27% through six treatment cycles. These findings provide solid evidence for further investigating the combination of biodegradation and photodegradation in wastewater treatment.

Mechanism of the Sliding Contact of a Ag-Graphite Brush against a Au-plated Slip Ring for Varying Ag Content

Mechanism of the Sliding Contact of a Ag-Graphite Brush against a Au-plated Slip Ring for Varying Ag Content

High-precision measurement of Ag isotopes for silicate rocks by MC-ICP-MS

A new protocol for the high-precision measurement of Ag isotopes for samples with low Ag contents by MC-ICP-MS.

A new MOF@bioactive glass composite reinforced with silver nanoparticles - a new approach to designing antibacterial biomaterials.

Multifunctional materials that combine antimicrobial properties with the ability to stimulate bone formation are needed to overcome the problem of infected bone defects. As a novel approach, a new composite based on bioactive glass nanoparticles in a simple system of SiO2-CaO (BG) coated with NH4[Cu3(μ3-OH)(μ3-4-carboxypyrazolato)3] (Cu-MOF) with additionally anchored silver nanoparticles (AgNPs) was proposed. Ag@Cu-MOF@BG obtained by the spin coating approach in the form of a disc was characterized using PXRD, ATR-FTIR, XPS, ICP-OES, and TEM. Importantly, the material retained its bioactivity, although ion exchange in the bioactive glass administered as a disc is limited. Hydroxyapatite (HA) formation was identified in TEM images after 7 days of immersion of the composite in a physiological-like buffer (pH 7.4, 37 °C). The Cu and Ag contents of Ag@Cu-MOF@BG were as low as 0.013 and 0.018 wt% respectively, but the slow release of the AgNPs ensured its antibacterial nature. Ag@Cu-MOF@BG exhibited antibacterial activity against all tested bacteria (E. coli, S. aureus, P. aeruginosa, and K. pneumoniae) with the diameter of the inhibition zones of their growth between 8 and 10 mm and the reduction index determined to be ≥3. Moreover, the biocompatibility of the new composite has been demonstrated, as shown by cell culture assays with human dermal fibroblasts (HDFs). The results from the migration test also proved that the HDF cell's phenotypic properties were not changed, and the cell adhesion and migration ability were the same as in control indirect assays.

Effects of Maternal Health During Pregnancy and Child Immunization on Mother-to-Child Transmission of Hepatitis B Virus: A Multicentre, Large-Sample Study in Southeast China.

High hepatitis B infection rates in China are a major public health issue, and mother-to-child transmission (MTCT) is a significant risk factor. This study was conducted with a prospective multicentre design from January 2021 to December 2022 in 245 hospitals providing midwifery services in southeastern China. The participants were pregnant women who were positive for hepatitis B surface antigen (HBs Ag) and their children. The HBs Ag concentration was tested in children aged 8-12 months. The odds ratio for each risk factor was calculated bylogisticregression analysis, and thedecisiontreemodel was used. A total of 5369 children born to hepatitis B-infected mothers between 8 and 12 months of age were enrolled, among whom 81 (1.51%) were positive for HBsAg. The risk factors for hepatitis B infection in 5369 children under one-year-old were a high intrauterine hepatitis B exposure level, a history of hepatitis B immunoglobulin (HBIG) delay beyond 12 hours after birth, and lack of full hepatitis B vaccine (HepB), with risks of 3.356 (1.223~9.209), 5.691 (1.931~16.773), and 5.137 (2.265~11.650), respectively. The discrimination accuracy of the decision tree was 98.5%. The risk factors for hepatitis B infection in 4542 children under one year old with high exposure risk were nonstandard treatment by the mother during pregnancy, HBIG delay beyond 12 hours after birth, and no complete HepB administration, with risks of 2.925 (1.063-8.047), 5.354 (1.806-15.871) and 5.147 (2.258-11.733), respectively. The discrimination accuracy of the decision tree was 98.3%. To prevent mother-to-child transmission of hepatitis B, it is necessary to standardize the treatment of pregnant women with a high exposure risk of hepatitis B, implement combined vaccination within 12 hours of birth, and standardise the full course of HepB.

Silver nanoparticles can be sampled by ultrafiltration probe but elution into & recovery from plasma and Dulbecco's Phosphate Buffered Saline differs in vitro.

Locally sustained release antimicrobials such as silver nanoparticles (AgNPs) might prove useful in combating local infections. Their elution has been investigated in Phosphate Buffered Saline (PBS) including from poloxamer 407 (P407). No information exists on possible interactions with proteins, nor have ultrafiltration (UF) probes been evaluated to measure Ag. These investigations would provide helpful data prior to investigating the sustained release after subcutaneous implantation in vivo over time. We compared (1) the influence of elution fluid on AgNP elution, and (2) UF probe and direct sampling in vitro. Six AgNP-P407 specimens in a dialysis tube were placed in Dulbecco's PPBS (DPBS) (n = 3) or canine plasma (n = 3) for 96 h on a stirred hot plate (37 °C and 600 rpm) and sampled 20 times. A 0.001 mg/mL AgNP solution was prepared in DPBS or plasma. Six pipette and UF probe samples were taken of each. Inductively coupled plasma mass spectrometry was used to analyze Ag. Stock plasma contained Ag. At 96 h, 5/6 dialysis tubes had not fully released AgNP. One peak in hourly Ag increase was present in DPBS (10-13 h), and two peaks in plasma (6-8 and 10-13 h). The hourly Ag increase in plasma decreased earlier than in DPBS. Ultrafiltration probe sampling was possible in both DPBS and plasma and resulted in higher Ag concentrations but with more variation. While in vitro use of DPBS might be more cost effective, plasma should be considered due to difference in elution and recovery. Ultrafiltration probes can be used to sample Ag, but results will have a greater degree of variation, and multiple samples and increased time points should be considered.

Silver Behavior During Magmatic and Magmatic-Hydrothermal Evolution of a Highly Evolved Reduced Granitic System Related to the Giant Shuangjianzishan Ag-Pb-Zn-(Sn) Epithermal Deposit, Northeast China

Abstract Magmatic-related epithermal silver-rich polymetallic deposits are among the most important sources of Ag in the world, and they are found associated with magmatic systems with striking differences. Most of the time, they are associated either with I-type oxidized (magnetite-series granite) intermediate to evolved intrusions or with S-type/A-type reduced (ilmenite-series granite) highly evolved intrusions. To better understand these associations, the Ag evolution has been tracked during the magmatic differentiation and the magmatic-hydrothermal transition stage of A-type highly evolved porphyritic granites associated with the giant Shuangjianzishan Ag-Pb-Zn-(Sn) epithermal deposit, the largest known Ag deposit of Asia (145 million tonnes at 128.5 g/t Ag and 2.2 wt % Pb + Zn) located in the largest known metallogenic province for Ag in China (the southern Great Xing’an Range). At the Shuangjianzishan deposit, the porphyritic granite complex consists of three temporally distinct intrusions—a coarse-grained monzogranite porphyry, a fine-grained syenogranite porphyry, and a fine-grained syenogranite—having crystallized at ~2 kbar and ~750°C and recording a continuous magmatic differentiation trend. The silicate melt that generated the last highly differentiated intrusion (fine-grained syenogranite) is interpreted as the source of the mineralizing fluids forming the Shuangjianzishan Ag-Pb-Zn-(Sn) epithermal deposit, as it is the only intrusive unit that reached fluid saturation, as indicated by cotrapped fluid and melt inclusions in quartz phenocrysts and by the occurrences of unidirectional solidification textures (USTs). Silver evolution in the different porphyritic granite facies was reconstructed with laser ablation-inductively coupled plasma-mass spectrometry analyses of quartz-hosted silicate melt inclusions, amphibole-hosted magmatic sulfide inclusions, and chemical modeling. The silicate melt forming the porphyritic granite complex was sulfide saturated during the first crystallization stage, as shown by the occurrence of Ag-rich monosulfide solid solution (MSS) inclusions hosted in amphibole phenocrysts from the coarse-grained monzogranite porphyry and from mafic microgranular enclaves hosted in the coarse-grained monzogranite porphyry. However, these Ag-rich MSSs had only a minimal impact on the Ag budget of the magmatic system, as shown by the increase of the Ag concentration (~100–1,000 ppb) in quartz-hosted silicate melt inclusions during the further evolution of the system until fluid exsolution was reached. These results combined with mass balance modeling suggest that Ag and Sn are efficiently transferred to the evolving residual melt during crystallization and crystal-melt segregation. The results of this study indicate that highly Ag endowed epithermal polymetallic deposits can be formed from the exsolution of Ag-rich mineralizing fluids from relatively low volume, highly evolved, reduced melts, similar to those responsible for the formation of Sn-rich greisen deposits.

Silver nanoparticle-decorated NiFe2O4/CuWO4 heterostructure electrocatalyst for oxygen evolution reactions.

In this work, Ag nanoparticles decorated with NiFe2O4/CuWO4 heterostructure were synthesized using the step-wise precipitation method. The influence of varying Ag loading on the NiFe2O4/CuWO4 heterostructure and its electrochemical OER performance was extensively studied in 1 M KOH electrolyte. The obtained LSV profile was analyzed to determine the overpotential, Tafel slope, and onset potential. The heterostructure with an optimal Ag loading of 5 wt% required the least overpotential (1.60 V vs. RHE) for generating a current density of 10 mA cm-2 with a lower Tafel slope of 44.5 mV dec-1, indicating its faster OER kinetics. Furthermore, the composite remained stable over a period of 24 hours with a minimum rise in the overpotential after the stability test. The enhanced OER performance of the as-prepared catalyst can be attributed to the presence of multiple metallic elements in the Ag-loaded NiFe2O4/CuWO4 composite, which created a diverse array of oxygen-vacant sites with varying reactivity, enhancing the charge-transfer kinetics; and thus contributing to the overall efficiency of OER. Therefore, optimizing the Ag concentration and engineering a microstructure represents an encouraging strategy for developing cost-effective catalysts for next-generation energy-conversion applications.

Synthesis and characterization of ZNO: CU and AG bimetallics nanoparticles by sol gel method

Different weight ratios of Cu-silver-doped and non-doped ZnO nanoparticles were created, By using XRD, FTIR, UV-visible spectroscopy, FESEM, and EDS the presence of nanoparticles in the sol-gel (ZnO) and (ZnO: Ag and Cu) techniques was confirmed, the JCPDS standard card for Zn (01-080-0074) validated the hexagonal ZnO structure by X-ray diffraction for (ZnO) and (ZnO:Ag and Cu). we calculated the average crystal size of all the produced samples, and we observe that the crystal size grows as the ratio of copper and silver doping rises. According to the FTIR data, O-H expansion is responsible for the expected distinctive absorption band in the vicinity of (3090-3665 cm). Because KBr quickly absorbs CO, it is possible that the peaks in the range (1550-1630 cm) are caused by the KBr utilized. These peaks are related to the stretching vibrations of C=O that are symmetric and asymmetric. The stretching vibration of the ZnO bond can be seen in the form of a prominent peak in the (350–780 cm) range. When Ag and Cu are entered to the doped ZnO samples, the peak strength declines, indicating the start of Ag and Cu clusters on the surface of ZnO nanoparticles. The bond position was shifted as a result of alteration in bond length brought about by the substitution of Ag+ ions at the ZnO lattice sites. According to the UV-VIS measurements, pure ZnO has a peak at 370 nm that becomes red at 569 nm. With increasing concentrations of Ag and Cu, the nanocomposites show high absorption in the visible region because the peaks shift monotonously to longer wavelengths and cause the energy gap value to decrease by 3, 2.958, 2.76, 2.74, 2.69, and 2.5 eV, respectively. According to the FESEM data from IMAGE J, the nanoparticles have a spherical or nearly spherical form. Zn, Ag, and Cu elements may be seen in the EDS data.

Synthesis of magnetite and her used by AgNO3 remove from aqueous system

Today pollution is an important problem that must be addressed, in this sense adsorption processes are a methodology that is usually used to remove different pollutants such as anions, cations and organic compounds. There is a great diversity of adsorbents ranging from porous oxides, metallic networks and polymeric membranes; magnetite and its composites have been shown to be adsorbent materials for the removal of various contaminants. The present work shows the study of the removal of Ag(I) from aqueous systems with Fe3O4 synthesized from precipitation processes. The magnetite showed an adsorption capacity of 19.84 mgg-1 according to the Langmuir adsorption model, a KL of 0.143 Lmg-1 , the partition coefficient showed a favorable adsorption with values between 0.1-0.01 and an endothermic Gibbs free energy. of 4.8 KJmol-1 . The kinetics of adsorption is carried out using a second order system, observing a decrease in the magnitude of the rate constant (K2) with the initial concentration of Ag(I), which suggests that the adsorption process at concentrations elevated is limited by the intra-particle diffusion of the system

Achieving the low emissivity of graphene oxide based film for micron-level electromagnetic waves stealth application

In recent years, the development of advanced materials with enhanced micron-level electromagnetic waves stealth properties has garnered significant attention due to their applications in fields such as military technology and thermal insulation. This study primarily investigates the stealth characteristics of materials within the 8–14 μm electromagnetic wave band, commonly known as the infrared (IR) spectrum. The effect of metallic Ag nanoparticles on the graphene oxide (GO) was obtained to achieve the excellent IR stealth ability. Specifically, Ag/GO composite films were prepared using a one-step reduction method and vacuum-assisted drying. The IR emissivity (8–14 μm) of the composites was significantly reduced with increasing Ag content, and the electrical conductivity of the materials was enhanced. When the Ag/GO mass ratio in the material was 1:2, the IR emissivity of the material at 8–14 μm was as low as 0.279, which was 62 % lower compared to GO. In addition, IR thermograms of the composites were analyzed using an IR thermographic camera. Obviously, the composites exhibited significant IR stealth properties when compared with those of GO. Thus, this work provides a reference for the preparation of carbon-based low IR emissivity materials for infrared stealth application.

Mineralogy of host rocks of the Osinovskoe gold-quartz deposit (Central Urals)

The paper describes the mineralogy of mica shales of the Osinovskoe gold deposit in the Central Urals. Our studies unraveled the role of dynamometamorphism in the transformation of primary rocks and allowed the characterization of their metasomatic alteration. We showed the relationship between plastic and brittle deformations and the formation of gold-bearing mineral assemblage with major pyrite, pyrrhotite and ilmenite and subordinate and rare sphalerite, chalcopyrite, marcasite, rutile, magnetite, molybdenum, galena, altaite, hessite, melonite, petzite, calaverite, volynskite, and sylvanite. The Ag content of native gold varies from 4 to 29 wt. %. Tellurides are associated with pyrite and pyrrhotite and also form monomineral grains and intergrowths in chlorite and mica with inclusions of REE minerals (xenotime-(Y), monazite-(Ce), hydroxylbastnesite-(Ce)), allanite-(Ce)), REE-bearing minerals (epidote, apatite, zircon), Th silicate (torite), and uraninite.

Tissue Distribution, Pharmacokinetics, and Effect of Hematological and Biochemical Parameters of Acute Intravenous Administration of Silver Nanoparticles in Rats.

The widespread biomedical and commercial applications of silver nanoparticles (AgNPs) have increased their potential for human and environmental exposure and toxicity to human health. The bio-distribution and toxicity of AgNPs in rodents following inhalation, intratracheal instillation, and oral ingestion are well documented; however, little is known about the bio-distribution of intravenously (IV)-administered AgNPs and their organ-specific pathophysiological effects. Here, we investigate the pharmacokinetic pattern and tissue distribution of AgNPs in male rats following IV administration. The animals were humanely sacrificed after 10 min, 1 h, 6 h, 12 h, 24 h, and 168 h of AgNP administration, and the silver (Ag) content was measured from blood samples and various tissues following acid digestion. The AgNPs were readily absorbed and subsequently distributed into most organs predominantly in the colon, small intestine, kidney, and heart after 6 h; however, they were the highest in the spinal cord after 168 h. White blood cells (WBCs) were significantly increased (42-60%) in AgNP-administered animals at all time points except 10 min. Regarding platelets, all AgNP-administered animals showed counts 7.8-39.2% lower, with the lowest count at 168 h post-administration. In the case of lymphocytes (LYMs), the AgNP-treated animals exhibited a count 19.5-41% lower at 10 min and 1 h post-administration; however, the animals at 168 h post-administration showed a count 30.5% more. The mean corpuscular hemoglobin (MCH) counts from the AgNP-treated animals were decreased by 50-62%. The concentrations of aspartate transaminase (AST), urea, and creatinine were increased in the AgNP-treated animals. Taken together, the results suggest that the acute IV administration of AgNPs alters metabolic and hematological parameters in animals and may pose a health risk to humans.

Radiophotoluminescence properties of Ag2O–Cs2O–BaO–Al2O3–P2O5 glasses

In this study, we synthesized Ag2O–Cs2O–BaO–Al2O3–P2O5 glasses with different Ag concentrations (0.1, 0.3, 1.0, and 3.0%) using the melt-quenching method and investigated the optical properties and the spatial resolution as an imaging plate. These glasses showed luminescence at around 340 nm upon 230 nm excitation before X-ray irradiation and luminescence at around 620 nm upon 340 nm excitation after X-ray irradiation. The lifetimes for the 340 and 620 nm emissions were 7.2–32.2 μs and 15.6–19.7 ns, respectively. Based on the emission wavelength and lifetimes, the luminescence at 340 and 620 nm was considered to originate from Ag+ and Ag2+, respectively. In other words, the results suggested that these glasses showed the radio-photoluminescence (RPL) phenomenon. The emission intensity of Ag2+ increased with annealing at 100–200 °C and disappeared by annealing at 600 °C in all the Ag-doped samples. The 3.0% Ag-doped sample indicated the highest emission intensity of Ag2+ and the spatial resolution of 10 LP/mm.