Distribution Of Silver Particles Research Articles

Numerical modeling of the process of extrusion of high-viscosity pastes

This paper provides a theoretical consideration of the process of paste extrusion using a piston dispenser. The paste is considered as a highly viscous suspension of terpineol and silver particle powder. As a result of numerical modeling, the distribution of silver particles in a steady paste flow was obtained. The excess pressure in the piston depending on its speed and the effective width of the track depending on the piston speed were obtained. Modeling showed that the viscosity of the paste has the greatest influence on the extrusion process. Application of the obtained dependencies will allow you to control the paste extrusion process.

Structural Analysis and Material Characterization of Silver Conductive Ink for Stretchable Electronics

Stretchable electronic systems have become more popular in various applications such as medical, fabric, flexible sensors for personalized health care, etc. There are two major parts of flexible and stretchable circuit boards that are substrate (a plastic material) and conductive ink (formulated polymer with conductive metal). According to electrical measurements, conductive ink plays a very important role in stretchable electronic equipment. The main objective of this paper is to develop a silver (Ag) based conductive ink and characterize its mechanical and electrical properties. Conductive ink is prepared by mixing an epoxy resin, cross –linking agent, additives (adhesion promoter), organic solvent, catalyst and silver flakes all together. ASTM D412 Type C dog bone shaped cutter is used to make three samples of conductive ink. The stress-strain analysis of conductive ink is carried out using universal testing machine (UTM). The conductivity is measured using two-point probe digital multi-meter. Also, the microstructural analysis, morphology and characterization are done by scanning electron microscopy (SEM). The images are taken after curing and tensile testing. The formulated ink possesses high conductivity and stretchability up to 137% strain. The achieved conductivity of the ink is 4.167×104S/m. The maximum stress before failure, yield stress, Young’s and tangent moduli are calculated as 1.195 MPa, 0.86 MPa, 5.72 MPa and 2.08 MPa, respectively. The SEM analysis indicates that the distribution of silver particles is uniform and in a good density throughout the sample.

Abnormal structure and properties of copper–silver bar billet by cold casting

Abstract Copper alloy rod billet with 20% silver was prepared using homemade three-chamber vacuum cold-type vertical continuous casting equipment. The variation rules of the microhardness, eutectic ratio, and size and distribution of silver particles precipitated in the primary α-Cu phase at the end of the continuous casting alloy rod blanks were studied using a microhardness tester and scanning electron microscope. The obtained results show that when the cold-type vertical continuous casting speed is 120 mm·min−1, there is obvious reverse segregation of solute element near the end of the prepared ∅7.8 mm copper–silver alloy rod blank. From the end of the continuous casting alloy rod blank to 5 mm from the end, the Cu–Ag eutectic structure in the copper–silver alloy increases from 13.4 to 15.9%, and the size of Ag particles precipitated in the primary α-Cu phase increases from 100 to 350 nm. The microhardness increases from 56 HV0.05 to 85 HV0.05. When the distance from the end exceeds 5 mm, the microstructure and properties of the continuous casting alloy rod blank are basically stable.

Features of the Semiconductor Surface structure containing silver particles on the porous Silicon Film Surface Formed by Metal-Assisted Etching

The porous silicon film surface region containing silver particles is studied by scanning electron microscopy and Raman spectroscopy. The porous silicon film is formed by metal-assisted etching of a single-crystal silicon substrate. It is found that the distribution of silver particles is controlled by the porous layer morphology. The formation of silver particles by chemical deposition results in certain smoothing of the por-Si film surface relief. In this case, the silicon crystallite structure does not change significantly.

Synthesis of graphene oxide ‐ based silver cotton fabric application for antibacterial activity

AbstractIn this study, silver/graphene oxide nanocomposites (Ag/GO) was synthesized via in situ method for antibacterial application. Silver/graphene oxide cotton fabric(Ag/GO/cotton fabric) was then synthesized via the dip ‐ coating method. The characteristics of GO, Ag/GO, and Ag/GO/cotton fabric were investigated with Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, Raman spectroscopy, and energy ‐ dispersive X‐ray spectroscopy. The results showed that the distribution of silver particles with an average size of 17.41±4.55 nm was uniformed on the GO sheets. The Ag/GO mounted on the fabric surface after coated. Pseudomonas aeruginosa ATCC 27853 (P. aeruginosa) and Staphylococcus aureus ATCC 25923 (S. aureus) were used to test the antibacterial activity of Ag/GO and Ag/GO/cotton fabric by disk diffusion method. The results demonstrated that Ag/GO displayed high antibacterial activity with minimum inhibitor concentration (MIC) value was 2.0 and 50.0 μg/mL with P. aeruginosa and S. aureus, respectively. The Ag/GO/cotton fabric was able to against two types of bacteria P. aeruginosa and S. aureus with diameter of inhibition zone was 5.00 and 2.50 mm, respectively. The results had prospective applications in a lot of fields like clothing, mask, and protective gear.

Anti-Escherichia coli Functionalized Silver-Doped Carbon Nanofibers for Capture of E. coli in Microfluidic Systems.

Silver-doped carbon nanofibers (SDCNF) are used as the base material for the selective capture of Escherichia coli in microfluidic systems. Fibers were spun in a glovebox with dry atmosphere maintained by forced dry air pumped through the closed environment. This affected the evaporation rate of the solvent during the electrospinning process and the distribution of silver particles within the fiber. Antibodies are immobilized on the surface of the silver-doped polyacrylonitrile (PAN) based carbon nanofibers via a three-step process. The negatively charged silver particles present on the surface of the nanofibers provide suitable sites for positively charged biotinylated poly-(L)-lysine-graft-poly-ethylene-glycol (PLL-g-PEG biotin) conjugate attachment. Streptavidin and a biotinylated anti-E. coli antibody were then added to create anti-E. coli surface functionalized (AESF) nanofibers. Functionalized fibers were able to immobilize up to 130 times the amount of E. coli on the fiber surface compared to neat silver doped fibers. Confocal images show E. coli remains immobilized on fiber mat surface after extensive rinsing showing the bacteria is not simply a result of non-specific binding. To demonstrate selectivity and functionalization with both gram negative and gram-positive antibodies, anti-Staphylococcus aureus surface functionalized (ASSF) nanofibers were also prepared. Experiments with AESF performed with Staphylococcus aureus (S. aureus) and ASSF with E. coli show negligible binding to the fiber surface showing the selectivity of the functionalized membranes. This surface functionalization can be done with a variety of antibodies for tunable selective pathogen capture.

Transport properties of hybrid materials based on perfluorosulfonic acid membranes and silver nanoparticles

Composite materials based on MF-4SK perfluorosulfonic acid membranes and silver nanoparticles with various distribution of the metal in the membrane matrix have been prepared. The influence of the concentration of a reducing agent on the distribution of silver particles in the bulk of the membrane has been revealed. It was shown that under certain conditions a conductive layer of reduced silver is formed on the membrane surface. The dependence of the diffusion permeability of the obtained mixed-matrix membranes on the quantity of the introduced silver and its spatial distribution within the membrane matrix has been determined.

Preparation and Study of Ink-Jet Printing of Ag Based Conductive Ink on Paper

Compared with the lithography and traditional technology, ink-jet printing technology has huge advantages such as reducing costs, improving production efficiency and reducing environment damage. The silver nanoparticles conductive ink used as core material in ink-jet printing technology has been greatly developed. At present, the conductive inks for printed circuit usually has high sintering temperature, low adhesion, poor mechanical properties, high cost, which limit the further industrial application. In this paper, nano silver pulp was prepared through liquid phase reduction method, and a self-made protective agent ensured that the particle size distribution of silver particles is about 5nm. The above silver pulp was dispersed in the organic resin to get conductive ink with 20% (wt%) silver content. Under 170°Csintering, the electrical conductivity of the ink layer was 1.15×104S/m.

Surface Modification Of Polyanniline Nanofiber Using Silver nanoparticles To Enhance Sensing Properties

The surface of polyaniline nanofibres is modified by silver nano particles using cyclic voltametry (CV). The surface modifications induced by silver particles are confirmed by scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and Raman spectroscopic techniques. The SEM micrographs show uniform distribution of silver particles on the surface of PANI nano fibers. Presence of silver particles was confirmed by EDX. Structural variations induced after reduction of Ag-metal particles and formation of polaron and bipolarons are studied by Raman spectroscopy. Copyright © 2013 VBRI press.

Ag/ZnO nanomaterials as high performance sensors for flammable and toxic gases

Ag/ZnO nanocomposites supported on polycrystalline Al2O3 were synthesized by an unprecedented approach combining plasma enhanced chemical vapor deposition (PE-CVD) of ZnO matrices and the subsequent deposition of Ag nanoparticles (NPs) by radio frequency (RF) sputtering. The system structure, composition and morphology were investigated by glancing incidence x-ray diffraction (GIXRD), secondary ion mass spectrometry (SIMS), field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDXS). A tailored dispersion and distribution of silver particles could be obtained under mild conditions by the sole variation of the sputtering time. Gas sensing properties toward flammable and toxic gases, both reducing (CH3CH2OH, CH3COCH3) and oxidizing (O3), were investigated in the temperature range 100–400 °C. Beside the high sensitivity, the developed sensors exhibited a response proportional to Ag content, thanks to catalytic and electronic effects promoted by silver NPs. In addition, discrimination between oxidizing and reducing analytes was enabled by a suitable choice of the adopted working temperature.

Characterization of Antibacterial, Mechanical, and Structural Properties of Polyvinyl Chloride/Silver Nitrate Composites Prepared by Thermoplastic Compounding

Polyvinyl chloride/silver nitrate composites were prepared by thermoplastic compounding. Antibacterial activity against gram-negative and gram-positive bacteria was determined by agar diffusion test. X-ray diffraction, X-ray photoelectron spectroscopy, and optical microscopy analyses were carried out to determine the effect of polyvinyl chloride modification on structural properties. The mechanical characteristics of prepared films were observed using stress-strain analysis. The results revealed that final composites exhibit sufficient antibacterial properties against tested bacteria, with nonuniform distribution of silver particles in the PVC matrix, which caused a decrease in mechanical properties. X-ray characterization proved the presence of the modifier, mostly in Ag+ form.

Effect of 125I labeled nerve growth factor on glioma cell line U251

Objective To explore radiotoxicity of 125I labeled nerve growth factor (125I-NGF) in U251. Methods Absorbance values of U251 treated with 18.5, 37.0, 74.0, 148.0, 296.0, 592.0,1184. 0, 1480. 0, 1850. 0, 2590. 0, 3330. 0, 3700. 0 kBq/ml 125I-NGF were detected by MTT assay. The corresponding minimum concentration of 125I-NGF tending to the minimum absorbance value was selected as minimum effective concentration, and was adopted in follow-up experiments. Plate colony-forming assay was adopted to compare the proliferation ability of cells treated with complete culture medium, 592 kBq/ml Na125I, 1 mg/L NGF and 592 kBq/ml 125I-NGF. Distribution of silver particles within the cells was observed by autoradiography to respond the existence of 125 I-NGF inside the cells. DNA damage was evaluated by comet assay and micronuclei forming assay. The proportion of cells in G0/G1 or S p hase was determined by flow cytometry. Results Minimal effective concentration of 125I-NGF was 592. 0 kBq/ml. Under thisconcentration, 125I-NGF could be transported to the nuclei of U251 and caused DNA damage. Being treated with 125I-NGF, U251 clone forming rate was (0. 02 ± 0. 01 ), compared to control group (0. 33 ± 0. 02),the proliferation of U251 was inhibited remarkably (P <0. 01 ). The proportion of cells in S phase ( 10. 69± 0. 02) was decreased, but that in Go/G1 phase ( 75. 10 ± 0. 22 ) increased remarkably ( P < 0. 01 ).Conclusion After being iodinated with 125I,125I-NGF can be transported to nuclei and causes DNA damage in U251. 125I-NGF has specific lethal effect on U251 cells in S phase. Key words: Radionuclide; Targeted therapy; Glioma

Preparation and characterization of trilobal activated carbon fibers

The objective of this research was to evaluate the effectiveness of several different methods for controlling the pore size and pore size distribution in activated carbon fibers. Variables studied included fiber shape, activation time, and the addition of small amounts of silver nitrate. Pure isotropic pitch and the same isotropic pitch containing 1 wt.% silver were melt spun to form fibers with round and trilobal cross sections. These fibers were then stabilized, carbonized, and activated in carbon dioxide. Field emission scanning electron microscopy (FE SEM), electron dispersive spectra (EDS), and wavelength dispersive spectra (WDS) were used to monitor the size and distribution of the silver particles in the fibers before and after activation. Each of these analyses showed that the distribution of silver particles was extremely uniform before and after activation. The fibers were also weighed before and after activation to determine the percent burn-off. The BET specific surface areas of the activated fibers were determined from N 2 adsorption isotherms measured at −196 °C. The results showed that round and trilobal fibers with equivalent cross-sectional areas yielded similar burn-off values and specific surface areas after activation. Also, activation rates were found to be independent of CO 2 flow rate. The porosity of the activated fibers depended on the total time of activation and the cross-sectional area of fibers. The N 2 adsorption measurements showed that the activated fibers had extremely high specific surface areas (greater than 3000 m 2/g) and high degrees of meso- and macro-porosity. FE SEM was also used to investigate surface texture and size of pore openings on the surfaces of the activated fibers. The photos showed that silver particles generated surface macro- and mesopores, in agreement with the inferences from N 2 adsorption measurements.

Formation and characterization of high-density silver nanoparticles embedded in silica thin films by “in situ” self-reduction

Silver nanoparticles (10–20 nm) embedded into silica thin films have been obtained through the use of a silver organometallic precursor compound dissolved in Spin-On-Glass and subsequently spinned onto suitable substrates. In this paper we present a study of the shape, size, and distribution of silver particles through the use of microscopes, x-ray diffraction, and optical extinction. It has been observed that the obtained films are stable for annealing up to 500 °C with a progressive degradation above this temperature. Furthermore it is possible to obtain high-density silver particles up to 15% in weight without affecting the cluster size and shape.

Variations in the Morphology of Image Silver Particles in Thermally Developed Photographic Materials

Photothermographic imaging systems based on silver halide and silver carboxylates have been utilized for a wide variety of imaging applications for many years. We have been investigating the morphology of silver particles formed in the image area of photothermographic imaging systems in order to understand the forces that affect their morphology. Because the size, shape, morphology and silver particle distribution within an image area affects the overall optical properties of the imaging material, control of these properties should lead to improved photographic responses of the materials. We have found in this investigation that there are multiple factors that influence the overall morphology of the silver particles, and show how morphological properties are changed by different conditions, e.g., the nature of the materials used, including the toners (succinimide, phthalimide, phthalazine), phenolic developers, and related components.

Scanning Force Microscopy Study of Methanol-Induced Changes in the Distribution of Silver Particles in Colloidal Metal Films

Colloidal silver particles were attached to a solid surface for use as a substrate for surface-enhanced Raman scattering and surface enhanced fluorescence spectroscopies. The enhancement of Raman scattering is dramatically increased after exposure of the substrates to methanol solution. Scanning force microscopy was used to visualize the substrate before and after the methanol treatment, and a statistical evaluation of the particle distribution revealed some differences. The nearest-neighbor distance was decreased after the exposure to methanol. This effect suggests that an aggregation of the particles occurred. This aggregation is probably based on increased attractive interactions and lateral mobility of the particles in methanol.

Biocompatibility of silver-coated polyurethane catheters and silvercoated Dacron ® material

The local effects of silver-coated polyurethane catheters and Dacron ® material were compared to uncoated polyurethane catheters and Dacron ® material in a long-term implantation test using rabbits. The tissue-implant interaction was analysed by investigating the type and number of inflammatory cells, capillaries, fat tissue, the extent of fibrosis, thickness of the fibrous capsule, number and distribution of silver particles, and the size of giant cells. Silver-coated and uncoated materials displayed comparable signs of inflammation and tissue reaction. Biomaterials (1994) 15, (10) 753–758

INFLUENCE OF Ag CONTENT ON OPTICAL PROPERTIES OF Ag-Cs2O THIN FILMS

The variations of glass refletance or front reflectance Rf, vacuum reflectance Rv and tran-smittance T of well activated cesium oxide thin films with Ag addition were measured within the visible and infrared range. Rv increases as the amount of Ag increases, but Rf decreases at first, then increases. Optical absorptions of the thin film and silver particles increase as the amount of Ag increases, and its photoemission increases at first, and then decreases. A model with inhomogeneous distribution of silver particles is proposed.