Nanoscale Silver Research Articles

The temperature-dependent fractional evolutional model for sintered nanoscale silver films

The sintered nano-silver has been popularly selected as die attachment and interconnection material in the next generation of high-power electronics packaging due to its low-temperature sintering and high-temperature operation. Considering the high temperature application condition, the temperature-dependent mechanical behaviors of sintered nanoscale silver have become one of reliability concerns in high power electronics. In this article, the effect of temperature has been combined with a variable fractional model to describe the temperature-dependent mechanical behaviors. The fractional order is physically interpreted by the strain hardening index. The changing law of involved parameters with respect to temperature is also revealed by the proposed model. The model is subsequently modified with a continuously varying fractional order for the whole tensile process instead of the piecewise one. The simulation results and comparisons with existing models exhibit that the modified model presents a simpler formulation without loss of fitting accuracy.

Plasmon resonance, thermal, and optical contributions to anti‐Stokes‐to‐Stokes line strength ratios in continuous wave‐excited surface‐enhanced Raman scattering spectra of molecules at random Ag surface

AbstractSurface‐enhanced Raman scattering (SERS) by biochemically relevant organic reporter molecules, spread out over a promising localized surface plasmon resonance (LSPR) structure of randomly arranged silver nanoscale particles (AgPs) of various dimensions and shape, was induced using tightly focused continuous wave (CW) 785‐nm laser radiation, and the spectra were registered simultaneously in the anti‐Stokes and Stokes spectral ranges. The spectra were recorded as a function of the excitation laser power density in the range of their profile reproducibility. The power density dependences of the line strength ratio for three respective pairs of vibrational lines of a thiolate of 2‐nitrobenzoic acid (TNB) in SERS spectra were derived. Using these data, we specify and quantify the contributions responsible for the discrepancy between this ratio and that defined by the thermal equilibrium populations of the upper and lower vibrational levels corresponding to the Raman‐active transitions. These contributions are the following: (i) the spectral profile of an LSPR contour, (ii) local heating of the reporter molecule/AgP conjugates by the 785‐nm radiation, and (iii) optical (Raman) pumping of the upper vibrational levels of the transitions involved. The extraction of the latter contribution enabled us to estimate the cross‐sections of the TNB/AgP conjugates Raman vibrational pumping by the radiation for each of the three vibrational modes.

Iodide ion removal from artificial iodine-containing solution using Ag-Ag2O modified Al2O3 particles prepared by electroless plating

A large amount of iodine-containing solution (ICS) is produced in both nuclear medicine and the atomic energy industry, which may cause serious health hazards in case if it enters aquatic ecosystem without sufficient treatment. The treatment of ICS by silver demonstrates great potential for iodine capture and retention. Nano-scale silver and its oxide particles formed on the surface of Al2O3 via electroless plating was introduced to ICS treatment. A series of batch sorption experiments against ICS by Ag-Ag2O modified Al2O3 (Ag-Ag2O-Al2O3) has been conducted. Ag-Ag2O-Al2O3 was characterized by SEM, FTIR, XRD, and XPS before and after the reaction. The results show that ~ 82.6% of I− was removed by 4.0 g/L Ag-Ag2O-Al2O3 from the solution containing 0.3 mg/L I− at pH 3 and at 298 K. Ag-Ag2O-Al2O3 was effective in low concentration artificial nuclear medical ICS treatment. Thermodynamic analysis showed that the reaction consistent with the Langmuir model and was a uniform exothermic reaction of a single layer. Therefore, Ag-Ag2O-Al2O3 prepared by electroless plating could be considered as a potential material for the ICS treatment.

Investigation of biological and photocatalytic activity of nanopowders metal oxides with nanosized silver coating

Was carried out the assessment of photocatalytic, cytotoxic properties on cells and antibacterial properties against E. coli and Staphylococcus of oxides nanopowders with nanoscale silver coating. Is shown the promising use of such composites as a photocatalytic agent, as well as in medicine.

Effect of annealing on metal nanoclusters tuned luminescence shift in Ag and Cu embedded nanocomposite glasses

Nanoscale silver and copper clusters are prepared in the soda-lime glass by sequential ion-exchange technique and thermal annealing process. The observed peak values of optical absorption spectroscopy result in the confirmation of embedded Ag and Cu nanoclusters in soda-lime glass. The effect of temperature on the plasmonic response has been investigated for various temperatures. The temperature dependence of surface plasmon resonance (SPR) shifted towards the blue wavelength region, due to growth of silver and copper nanoclusters. Similar to the absorption peak shift, the blue shift in emission spectra has been observed in the photoluminescence spectra of embedded Ag and Cu nanoclusters. The optical bandgap values of Ag and Cu nanoclusters are determined from Tauc's plot. The bandgap variations with luminescence spectra and their emission peak shift with the temperature make them as a promising material for temperature sensors. The FESEM images confirm the cluster distribution of these embedded metal nanoparticles.

Nanoscale Silver Iodobismuthate Photosensitizer and Its Hybridization with Molecular Dye for Mesoporous TiO2 Film-based Solid-state Sensitized Solar Cells

Nanoscale Ag2Bi3I11 photosensitizer was prepared on mesoscopic TiO2 film (∼1 µm thick) by spin-coating of its low-concentrated precursors. The as-prepared Ag2Bi3I11-sensitizer was tested in the for...

Identification and Speciation of Nanoscale Silver in Complex Solid Matrices by Sequential Extraction Coupled with Inductively Coupled Plasma Optical Emission Spectrometry.

Nanoscale silver (n-Ag) including silver nanoparticles (Ag-NPs), silver chloride nanoparticles (AgCl-NPs), and silver sulfide nanoparticles (Ag2S-NPs) and their corresponding ionic counterpart, namely, dissolved Ag, may coexist in soils. X-ray absorption near edge spectroscopy (XANES) is used to elucidate the speciation of n-Ag in soils, whereas it possesses drawbacks like high costs, rare availability of the instrument, and providing semiquantitative data. We developed a new method for the identification and speciation of n-Ag in soils and sediments based on a sequential extraction technique coupled with inductively coupled plasma optical emission spectrometry. Extraction conditions were first evaluated, establishing the optimal extraction procedure; Ag-NPs, AgCl-NPs, and dissolved Ag in soil were simultaneously extracted by using an aqueous solution of 10 mM tetrasodium pyrophosphate, followed by selective isolation and quantification via AgCl-NPs dissolution (4.45 M aqueous ammonia), centrifugation (Ag-NPs), and detection. The Ag2S-NPs remaining in the soil were then extracted with Na2S solution at pH 7.0 through selective complexation. Optimal recoveries of Ag-NPs, AgCl-NPs, Ag2S-NPs, and dissolved Ag were 99.1 ± 2.4%, 112.0 ± 3.4%, 96.4 ± 4.0%, and 112.2 ± 4.1%, respectively. The method was validated to investigate the speciation of n-Ag in soils and sediments, exhibiting the distribution of Ag-NPs, AgCl-NPs, Ag2S-NPs, and dissolved Ag in each sample, wherein Ag2S-NPs, the major species of n-Ag, accounted for 35.42-68.87% of the total Ag. The results of n-Ag speciation in soil are comparable to those obtained through the linear combination fitting of XANES. This method thus is a powerful, yet convenient, substitute for XANES to understand the speciation of n-Ag in complex solid matrices.

Facile green preparation of nano-scale silver particles using Chenopodium botrys water extract for the removal of dyes from aqueous solution

In this study, the silver nanoparticles (AgNPs) as an eco-friendly, efficient and low-cost adsorbent was synthesized from Chenopodium botrys extract. Characteristics of the prepared adsorbent were investigated using scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDAX). According to the particle size distribution, the average size of AgNPs was obtained 11.9 nm. AgNPs were used for methyl blue (MB) and methyl orange (MO) removal from aqueous solution. Maximum removal percentages of 97.50 and 95.00 was obtained under optimum conditions, including contact time of 25 min, pH = 10, adsorbent dosage of 0.9 g, and dye concentration of 30 mg/L for MB and MO, respectively. Langmuir isotherm indicated the best results of adsorption related to the MB and MO with the maximum adsorption capacity of (qmax) 90.09 and 80 mg g−1 for MB and MO, respectively. The kinetics study showed that the results were fitted to the pseudo-second-order model with the coefficient of determination (R2) of 0.9984 and 0.9919 for MB and MO, respectively. The process of removal can be also by adsorption of dye molecule on the surface of Ag-NPs and also may be due to the removal of dye molecules by hydroxyl radicals generated by the NPs effect on water molecules in the presence of light. The proposed adsorbent with its great properties can be used to remove contaminants from industrial wastewater before discharge to the environment.

Study of Wound-Healing Ointment Composition based on Highly Dispersed Zinc Oxide Modified with Nanoscale Silver

A complex modern study of the ratio effect of components of an ointment composition based on highly dispersed Zinc oxide modified with nanoscale silver on its physical and chemical properties is performed. It was found that at a concentration of glycerol equal to C = 10%, and at a concentration of methylcellulose C = 3%, the value of the active acidity of the ointment composition is optimal (pH = 6.5-7). Studies of the structural and mechanical properties of the ointment composition have shown t

Interactions between Nanoscale Zerovalent Iron and Silver Nanoparticles Control the Reactivity in Aqueous Environments

Interactions between Nanoscale Zerovalent Iron and Silver Nanoparticles Control the Reactivity in Aqueous Environments

Effects of rhamnolipid biosurfactant on the dissolution and transport of silver nanoparticles in porous media

The effects of nanoscale silver (nAg) particles on subsurface microbial communities can be influenced by the presence of biosurfactants, which have been shown to alter nanoparticle surface properties.

Unraveling the Active Biomolecules Responsible for the Sustainable Synthesis of Nanoscale Silver Particles through Nuclear Magnetic Resonance Metabolomics

We have investigated the sustainable synthesis of silver nanoparticles (AgNPs) using blueberry (Vaccinium corymbosum L.) ethanolic extract from the point of view of the intervening metabolites. An extensive NMR metabolomic approach based on nuclear magnetic resonance (NMR) spectroscopy and headspace-solid phase microextraction (HS-SPME) followed by gas chromatography/quadrupole-mass spectrometry (GC–qMS) has been directed in order to ascertain for the first time the involved bioactive molecules as those responsible for the synthesis of AgNPs. The green process was monitored through UV–vis spectrophotometry, and a plethora of techniques such as EDX, XRD, XPS, TEM, SEM, and DLS were used to confirm the formation of the AgNPs. The successful synthesis was indirectly proven by their antibacterial activity against Gram-positive Streptococcus pyogenes and Gram-negative bacteria Salmonella typhi.

ПРОФИЛАКТИКА ТОКСИКО-АЛЛЕРГИЧЕСКИХ РЕАКЦИЙ ПРИ ИСПОЛЬЗОВАНИИ СЛОЖНОЧЕЛЮСТНЫХ ПРОТЕЗОВ И АППАРАТОВ

Subject. Today, nanoparticles of chemical elements that make up the body are of particular interest. Such nanomaterials usually do not cause allergic reactions, they can potentially be broken down and removed from it, and, for example, drugs can be placed in the pores of these materials. At the Department of Prosthetic Dentistry of V.G. N.N. Burdenko together with Voronezh State University developed a polymer modified with nanosized silver particles, which was successfully tested on patients in the manufacture of removable plate prostheses. However, there is no data on the effect of this polymer in patients with complex jaw pathology in combination with somatic pathology, in which visible changes occur in the oral cavity. 
 Goal ― to consider the problem of prevention of toxic-allergic reactions when using complex-jaw prostheses and devices. To study the state of the oral microbiocenosis and the cytological characteristics of the mucous membrane in patients with apparatus bases made of a polymer modified with nanoscale silver. Materials and methods. 80 people were examined and 60 patients were treated for complete absence of teeth with various degrees of atrophy according to A.I.Doynikov (1967) I, II, III, IV, V, with a uniform quantitative distribution in groups. 
 Methodology. 80 people were examined and 60 patients were treated for complete absence of teeth with various degrees of atrophy according to A.I.Doynikov (1967) I, II, III, IV, V, with a uniform quantitative distribution in groups. 
 Results. The dynamics of the inflammatory processes of the mucous membrane of the prosthetic bed under the bases of removable jaw devices made by the known method and with bases from modified materials was studied. A complex of personalized prevention of complications associated with the action of basic polymers has been developed. 
 Conclusion. Obtained by analyzing the results of the study, it was possible to create, on the basis of the use of modified acrylic polymer as the material of the bases of removable prostheses and devices, a program for individual prevention of the inflammatory complications induced by them from the mucosa of the prosthetic bed, the efficiency level of which is at least 60 %. This predisposes to recommendations for the further implementation of the modified nanosilver acrylic polymer in practical dentistry.

Sunlight-Induced Synthesis of Non-Target Biosafety Silver Nanoparticles for the Control of Rice Bacterial Diseases.

Silver is an important and efficient bactericide. Nanoscale silver has a large specific surface area, high target adhesion, strong permeability and high bactericidal activity. At present, the control of plant bacterial diseases is difficult, and the resistance of plant bacterial pathogens develops rapidly. Silver nanoparticles are expected to become a new generation of agrochemical to control plant bacterial diseases. In this study, a simple and green natural sunlight-induced method was used to prepare carboxymethylcellulose sodium-stabilized silver nanoparticles (CMC-SNs) with a particle size of around 13.53 ± 4.72 nm. CMC-SNs were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD) and UV-vis spectroscopy and found to be spherical and evenly dispersed. The bacteriostatic activity of the CMC-SNs toward Xanthomonas oryzae pv. oryzae (Xoo) was tested. The minimum inhibitory concentration (MIC) of CMC-SNs to Xoo was 1 mg/L, and the minimum bactericidal concentration (MBC) was 2 mg/L. In addition, the antibacterial mechanism was studied by scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM), which confirmed that the CMC-SNs had high antibacterial activity. In order to verify its impact on the environment, we conducted an acute toxicity test on zebrafish and found that Half lethal concentration (LC50) > 100 mg/L in zebrafish, or no acute toxicity. The ability of CMC-SNs to control rice bacterial blight was verified by a pot experiment.

Carbon-based nanomaterials suppress tobacco mosaic virus (TMV) infection and induce resistance in Nicotiana benthamiana

Although nanomaterials (NMs) may inhibit viral pathogens, the mechanisms governing plant–virus–nanomaterial interactions remain unknown. Nicotiana benthamiana plants were treated with nanoscale titanium dioxide (TiO2) and silver (Ag), C60 fullerenes, and carbon nanotubes (CNTs) at 100, 200 and 500 mg L−1 for a 21-day foliar exposure before inoculation with GFP-tagged tobacco mosaic virus (TMV). Plants treated with CNTs and C60 (200 mg L−1) exhibited normal phenotype and viral symptomology was not evident at 5 days post-infection. TiO2 and Ag failed to suppress viral infection. RT-qPCR analysis revealed that viral coat protein transcript abundance and GFP mRNA expression were reduced 74–81% upon CNTs and C60 treatment. TEM revealed that the chloroplast ultrastructure in carbon NM-treated plants was unaffected by TMV infection. Fluorescence measurement of CNTs and C60 (200 mg L−1) treated plants indicated photosynthesis equivalent to healthy controls. CNTs and C60 induced upregulation of the defense-related phytohormones abscisic acid and salicylic acid by 33–52%; the transcription of genes responsible for phytohormone biosynthesis was elevated by 94–104% in treated plants. Our findings demonstrate the protective role of carbon-based NMs, with suppression of TMV symptoms via hindered physical movement and viral replication. Given the lack of viral phytopathogen treatment options, this work represents a novel area of nano-enabled agriculture.

Self-lubricating and high wear resistance mechanism of silver matrix self-lubricating nanocomposite in high vacuum

The silver matrix self-lubricating nanocomposite with low friction and high wear resistant was fabricated by nanoscale silver powder, nanoscale tungsten disulfide powder and microscale molybdenum disulfide powder. The friction and wear behaviors were investigated, and the worn surfaces were observed and analyzed by SEM and XPSXPS. The investigations on transfer layer and lubricating film were used to analyze the friction and wear properties of the materials, and self-lubricating and high wear resistance mechanism of the nanocomposite was discussed. Decreasing the velocity could increase the thickness of lubricating film, and the thickest lubricating film (about 117 nm) was achieved at a velocity of 0.1 m/s. It is confirmed that the nanocomposite had a significant improvement in friction and wear properties, the low friction coefficient and high wear resistance in high vacuum were 0.125 and 2.53 × 10−6 mm3/N·m, respectively. The transfer layers and lubricating films containing tungsten disulfide and molybdenum disulfide has better self-lubricating property than the transfer layer containing the single solid lubricant. The synergistic effect of binary solid lubricants was confirmed in Nanocomposite.

Development and Characterization of Membranes with PVA Containing Silver Particles: A Study of the Addition and Stability

Developing technologies for the reduction of biofouling and enhancement of membrane functionality and durability are challenging but critical for the advancement of water purification processes. Silver (Ag) is often used in the process of purification due to its anti-fouling properties; however, the leaching of this metal from a filtration membrane significantly reduces its effectiveness. Our study was designed to integrate the positive characteristics of poly vinyl alcohol (PVA) with the controlled incorporation of nano-scale silver ions across the membrane. This approach was designed with three goals in mind: (1) to improve antifouling activity; (2) to prevent leaching of the metal; and (3) to extend the durability of the functionalized membrane. The fabrication method we used was a modified version of manual coating in combination with sufficient pressure to ensure impregnation and proper blending of PVA with cellulose acetate. We then used the spin coater to enhance the cross-linking reaction, which improved membrane durability. Our results indicate that PVA acts as a reducing agent of Ag+ to Ag0 using X-ray photoelectron spectroscopy analysis and demonstrate that the metal retention was increased by more than 90% using PVA in combination with ultraviolet-photo-irradiated Ag+ reduced to Ag0. The Ag+ ions have sp hybrid orbitals, which accept lone pairs of electrons from a hydroxyl oxygen atom, and the covalent binding of silver to the hydroxyl groups of PVA enhanced retention. In fact, membranes with reduced Ag displayed a more effective attachment of Ag and a more efficient eradication of E. coli growth. Compared to pristine membranes, bovine serum albumin (BSA) flux increased by 8% after the initial addition of Ag and by 17% following ultraviolet irradiation and reduction of Ag, whereas BSA rejection increased by 10% and 11%, respectively. The implementation of this hybrid method for modifying commercial membranes could lead to significant savings due to increased metal retention and membrane effectiveness. These enhancements would ultimately increase the membrane’s longevity and reduce the cost/benefit ratio.

Facile fabrication of size-controlled Ag@PI hybrid nanotubes and its photocatalytic performance

Here, we report for the first time on the successful fabrication of size-controlled silver@polyimide (Ag@PI) hybrid nanotubes (NTs) based on a silver ion-induced crosslinking effect via coaxial electrospinning and direct ion exchange-reduction techniques. By simply altering the coaxial electrospinning parameters and concentration of electrospinning solution, the diameter and wall thickness of the Ag@PI hybrid NTs could be finely tuned in the range of 300–900 nm and 50–200 nm, respectively. This hybrid material possesses a special conductive/dielectric-layered nanotubular structure, integrating the advantages of nanoscale silver and PI materials. The photocatalysis of the Ag@PI hybrid NTs was characterized by the decolorization of the Methylene Blue (MB) solution. The decolorization efficiency of MB can be as high as 90% within 210 min in the presence of Ag@PI NTs.

Designing AgFeO2-graphene/Cu2(BTC)3 MOF heterojunction photocatalysts for enhanced treatment of pharmaceutical wastewater under sunlight

In this work, nanoscale silver ferrite (AgFeO2) was successively impregnated onto graphene(G) and Cu2(BTC)3 MOF to construct binary and tertiary heterojunction photocatalysts with engineered bandgap energies (Eg = 1.95 to 1.72 eV) for photocatalytic removal of pharmaceutical drug pollutants under sunlight irradiation. Response surface methodology was employed to investigate and optimize the prepared photocatalysts for visible-driven photodegradation of amoxicillin (AMC) and diclofenac (DCF) (as model drug pollutants) under the effect of irradiation time (XT), drug concentrations (XC), and water salinity (XS). At optimum conditions (XT: 100 min, XC: 5 mg/L, and XS: 250 mg/L), all photocatalysts exhibited high sensitivity for solution pH due to the ionization of AMC/DCF molecules, which influences their adsorbability on the photocatalysts surfaces. Under sunlight irradiation, AgFeO2/G@Cu2(BTC)3 outperformed other binary photocatalysts (AgFeO2/G and AgFeO2/Cu2(BTC)3) towards AMC/DCF drug pollutants removal (up to 97 % after 150 min), with apparent photo-kinetic (k1) rates of 6.4–8.7 × 10−2 min-1 and excellent stability up to four cycles. More importantly, AgFeO2/G@Cu2(BTC)3 heterojunction showed high efficacy to remediate real pharmaceutical wastewater with an efficiency of 87.1 ± 2.9% reduction in chemical oxygen demand (COD) after 7 h under direct sunlight. The enhanced photocatalytic activity of the tertiary heterojunction photocatalyst is attributed to promoted charges transfer mechanism via direct Z-scheme from the conduction band of Cu2(BTC)3 to the valence band of AgFeO2 in the presence of graphene as a solid electron mediator/acceptor. Hence, the photogenerated electrons in the conduction band of AgFeO2 reacted with O2 molecules to generate O2−anion (as predominant oxidative species), which successively enhances the degradation/mineralization of adsorbed drug molecules on the catalyst surfaces.

Optical detection of the percolation threshold of nanoscale silver coatings with optical fiber gratings

The metal-to-dielectric transition of silver films deposited on single-mode optical fibers is monitored by measurements of the transmission spectra of tilted fiber Bragg gratings inscribed in the core of the fiber. In situ, real-time measurements of the spectrum at wavelengths near 1550 nm during the wet etching of a 50 nm thick silver coating show a sudden and temporary decrease of more than 90% in the amplitudes of the core-to-cladding mode coupling resonances when the film thickness reaches 18 nm. Confirmation that this observation corresponds to the percolation threshold is obtained from simultaneous measurements of the silver coating conductivity during etching and by simulations of the grating response. The characteristic spectral signature of the percolation threshold is only obtained for cladding modes polarized azimuthally in the fiber cross section, i.e., parallel to the film surface.