Dilute Silver Research Articles

Numerical Calculation of the Thermodynamic Properties of Silver Erbium Alloys for Use in Metallic Magnetic Calorimeters

Using dilute silver erbium alloys as a paramagnetic temperature sensor in metallic magnetic calorimeters (MMCs) has the advantage of the host material not having a nuclear quadrupole moment, in contrast to the alternative of using gold erbium alloys. We present numerical calculations of the specific heat and magnetization of Ag:Er, which are necessary for designing and optimizing MMCs using this type of alloy as sensor material. The parameter ranges we consider are temperatures between 1,{text {{mK}}} and 1,{text {{K}}}, external magnetic fields of up to 20,{text {{mT}}}, and erbium concentrations of up to 2000,{text {{ppm}}}. The system is dominated by an interplay of crystal field effects, Zeeman splitting, and the RKKY interaction between erbium ions, with certain specific constellations of erbium ions having noticeable effects on the specific heat. Increasing the external magnetic field or assuming a decreased strength of the RKKY interaction leads to a higher magnetization and a narrowing of the main Schottky peak, while changes in the erbium concentration can be well described by parameter scaling.

Dilute Silver Diamine Fluoride (1:10) Versus Light Cure Calcium Hydroxide as Indirect Pulp Capping Agents in Primary Molars - A Randomized Clinical Trial.

To evaluate the clinical and radiographic outcomes of diluted silver diamine fluoride (1:10) and light cure calcium hydroxide as indirect pulp capping agents in primary molars. Fifty-six primary molars requiring indirect pulp treatment were randomly allocated to two groups: Dilute SDF (one drop of SDF mixed with 9 drops of distilled water giving a 1:10 dilution) and light cure calcium hydroxide. The indirect pulp treatment was followed by glass ionomer cement restoration and all primary molars received stainless steel crown as full coverage restoration. The teeth were followed up both clinically and radiographically at 1,6- and 12-months' time interval using a pre-determined criterion. The results were statistically analyzed using Chi square analysis. The significance level was set at p ≤0.05. Overall clinical and radiographic success rate of indirect pulp treatment with SDF was 96% and with light cure calcium hydroxide was 91.6% respectively at the end of 12 months but the difference was not statistically significant (p>0.05). Dilute silver diamine fluoride (1:10) can be advocated as potential indirect pulp capping agent in primary molars with deep carious lesions.

Hydrothermal sterilization in silver nitrate solution endows plasma sprayed hydroxyapatite coating with antibacterial property

Plasma sprayed hydroxyapatite (HA) coatings are widely used on bone implants due to excellent osteoconductivity. However, the coating also provides an appropriate environment for biofilm formation. To prevent bacteria adhesion, this study tried to modify the HA coating with silver (Ag) by hydrothermal sterilization in dilute silver nitrate (AgNO3) solution at 121 °C for 20 min. Surface morphology, phase and chemical composition and antibacterial ability of the sterilized coating were investigated. After treatment, Ag was successfully incorporated onto the HA coating surface as in situ growing silver phosphate (Ag3PO4) compound and the distribution of Ag element was homogeneously. Inhibition zone test showed that, the sterilized HA coating had an excellent antibacterial ability against Staphylococcus aureus (S. aureus). This simple and feasible method shows promising potential for clinical applications.

Biosynthesis of Ag 3 PO 4 nanoparticles in the absence of phosphate source using a phosphorus mineralising bacterium

Silver phosphate nanoparticles were biologically synthesised, for the first time, using a dilute silver nitrate solution as the silver ion supplier, and without any source of phosphate ion. The applied bacterium was Sporosarcina pasteurii formerly known as Bacillus pasteurii which is capable of solubilising phosphate from soils. It was speculated that the microbe accumulated phosphate from the organic source during the growth period, and then released it to deionised water. According to the transmission electron microscopy images and X-ray diffraction results, the produced nanoparticles were around 20 nm in size and identified as silver phosphate nanocrystals. The outcomes were also approved by energy-dispersive X-ray analysis, thermogravimetric and differential scanning calorimetry analyses, ultraviolet–visible spectroscopy, and Fourier transform infrared spectroscopy analysis. Finally, the antibacterial effect of the obtained nanoparticles was verified by testing them against Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium. The activity of silver phosphate nanoparticles against gram-negative strains was better than the gram positives. It should be mentioned that the concentrations of 500 and 1000 mg/l were found to be strongly inhibitory for all of the strains.

Synthesis of silver nanoparticles from a Desmodium adscendens extract and its antibacterial evaluation on wound dressing material.

The one-pot synthesis of silver nanoparticles (AgNPs) using the medium-polar extract of Desmodium adscendens (Sw.) DC. is presented here as an alternative synthesis of metal NPs. Characterisation of the formed NPs showed polydispersed AgNPs ranging from 15 to 100 nm where the concentration of metal ions was found to play a role in the size and shape of the prepared NPs. It could be established that the flavonoids, saponins, and alkaloids present in the extract acted as both reducing and stabilising agents during the formation of the capped metal NPs. This means of NP synthesis was also employed during the in situ immobilisation of AgNPs on gauze and plaster. An evaluation of the antibacterial activity of the medium-polar D. adscendens extract, AgNPs suspended in solution, and the immobilised AgNPs against Staphylococcus aureus (ATCC 25923), Bacillus cereus (ATCC 11778), and Escherichia coli (ATCC 25922) showed high efficacy against the latter in particular. This suggests that gauze, dilute silver nitrate solutions, and D. adscendens extract could be used successfully in the simple in situ preparation of effective antibacterial wound dressings.

Assessing Photocatalytic Activity at the Nanoscale Using Integrated Optical and Electron Microscopy

An integrated optical‐electron microscope is presented that enables the in situ study of dynamic processes on photoactive materials. Here, the deposition of metallic silver nanostructures at ZnO photocatalyst particles is monitored in real time under ambient conditions by means of scanning electron microscopy. Zinc oxide crystals are immobilized on an electron transparent silicon nitride window. By passing UV light through an opposing optically transparent window, the zinc oxide is illuminated resulting in the photocatalytic formation of silver nanostructures. Both windows are part of a specially designed liquid cell filled with a dilute aqueous silver nitrate solution. Using the presented system, different electron detectors are evaluated for their ability to provide detailed images despite the interference caused by the liquid surrounding the sample. Special care has to be taken since direct silver reduction from solution induced by the electron beam interferes with the photocatalytic process. Oxygen gas, produced during the photocatalytic reaction, is also shown to complicate the imaging of the dynamic nanoscale processes in the scanning electron microscope. Nevertheless, the integrated approach allows to directly establish structure–activity relationships and to unravel optically induced processes at nanostructured materials.

Synthesis Procedures for Silver Nanoparticles

This article gives some proposals on how to grow silver nanoparticles using different methods. Dilute silver salts are recommended as the metal precursor starting solutions. The formation of the silver nanoparticles is to be monitored using UV-Vis absorption spectroscopy so as to reveal the formation of silver nanoparticles and how they will exhibit surface plasmon absorption maxima at 418-420 nm from the UV–Vis spectrum. The Mie light scattering theory will be applied and the experimental results analyzed to show the diameter of silver nanoparticles in colloidal solution. Energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–Vis spectroscopy are proposed to be used to characterize the formed silver nanoparticles obtained. The energy-dispersive spectroscopy (EDX) of the nanoparticles dispersion will confirm the presence or absence of elemental silver signal peaks. The size and morphology of the formed silver nanoparticles will be determined by transmission electron microscopy. The synthesized silver nanoparticles will be structurally characterized by using X-ray diffraction and transmission high-energy electron diffraction (HEED) and the peaks in the XRD pattern will be compared to the standard values of the face-centeredcubic form of metallic silver (ICCD-JCPDS card no. 4-0787).

Characterization of Micro- and Nanoscale Silver Wires Synthesized Using a Single-Replacement Reaction between Sputtered Copper Metal and Dilute Silver Nitrate Solutions

This paper describes an experiment developed to provide students enrolled in introductory nanotechnology and introductory chemistry courses with an opportunity to synthesize silver nanowires using a bottom-up nanofabrication technique. The reaction between copper metal sputter coated on silicon dioxide and a dilute silver nitrate solution is used to create the nanowires. Included in this experiment is a characterization component allowing students to analyze the nanowires using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Microscale silver wires are also produced in the reaction, making it possible for students to utilize optical microscopy, in addition to AFM and SEM, for silver wire characterization. The silver nanowire synthesis reported in this paper does not require the use of nanoporous templates or hazardous purification steps to liberate wires from template confinement.

Synthesis Procedures for Silver Nanoparticles

This article gives some proposals on how to grow silver nanoparticles using different methods. Dilute silver salts are recommended as the metal precursor starting solutions. The formation of the silver nanoparticles is to be monitored using UV-Vis absorption spectroscopy so as to reveal the formation of silver nanoparticles and how they will exhibit surface plasmon absorption maxima at 418-420 nm from the UV–Vis spectrum. The Mie light scattering theory will be applied and the experimental results analyzed to show the diameter of silver nanoparticles in colloidal solution. Energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–Vis spectroscopy are proposed to be used to characterize the formed silver nanoparticles obtained. The energy-dispersive spectroscopy (EDX) of the nanoparticles dispersion will confirm the presence or absence of elemental silver signal peaks. The size and morphology of the formed silver nanoparticles will be determined by transmission electron microscopy. The synthesized silver nanoparticles will be structurally characterized by using X-ray diffraction and transmission high-energy electron diffraction (HEED) and the peaks in the XRD pattern will be compared to the standard values of the face-centered-cubic form of metallic silver (ICCD-JCPDS card no. 4-0787).

Thermodynamics of oxygen in dilute liquid silver-tellurium alloys.

The activity coefficient of oxygen f_{text{O}}^{0} in liquid Ag and binary Ag–Te dilute alloys were determined between 1,285 and 1,485 K by coulometric titration using the electrochemical cell (Ir, [O] in liquid metal or alloy | yttria stabilized zirconia | air, Pt). The experimental and evaluation procedures described in the literature were adopted. The oxygen activity coefficient was determined in pure liquid silver to be ln f_{text{O}}^0 = {{ - 1{,}760.2} mathord{left/ {vphantom {{ - 1,760.2} T}} right. kern-nulldelimiterspace} T} + 0.6315. Next, the oxygen activity coefficient in dilute Ag–(Te)–O alloys for variable X Te content (from 0.01 to 0.06) was measured. From the obtained results, Wagner’s interaction parameter varepsilon_{text{O}}^{text{Te}} as a function of temperature was derived in the form varepsilon _{text{O}}^{{text{Te}}} left( { pm 0.32} right) = {{ - 18,483} mathord{left/ {vphantom {{ - 18,483} T}} right. kern-nulldelimiterspace} T} + 7.668. The electrochemical coulometric titration method seems to be very useful to study the thermodynamics of oxygen interaction in liquid silver and its alloys.Graphical abstract

Inkjet Printing of Electrically Conducting Micron-Wide Lines and Transparent Conducting Films by Edge-Enhanced Twin-Deposition

ABSTRACTRoll-to-roll manufacturing holds the potential to rapidly and cheaply produce electronic devices in a flexible format as well as to effectively scale up production of emerging nanotechnologies. Developing scalable techniques for the efficient and effective use of solution-processed functional material is a significant factor in realizing the potential of roll-to-roll manufacturing. We present a novel inkjet deposition process developed to rapidly deposit arrays of micron-wide lines of silver nanoparticles for use as an optically transparent and electrically conducting film. The technique involves jetting a controlled number of space-overlapped drops of a dilute nanoparticle silver ink onto a substrate to form a long stable ink rivulet with two parallel and pinned edges. Subsequently, nanoparticles deposit preferentially at the two parallel rivulet edges due to edge-enhanced evaporation of the solvent. The final result is a twin-deposit of parallel continuous nanoparticle lines, each with a characteristic width less than 5μm and height less than 300 nm. The twin lines are separated by a predominantly particle-free region with the spacing between the lines ranging from 100 μm to 600 μm, where the spacing is a function of ink, substrate, and printing conditions. The effect of substrate surface and jetting parameters on nanoparticle line morphology is presented. Arrays of such lines have been printed and evaluated as potential transparent conducting films, showing an effective sheet resistance of ∼5 Ω/□. This edge-enhanced twin-deposition technique has the potential for rapid, material-efficient, and lithography-free patterned deposition of functional material for use in roll-to-roll manufacturing.

Colouring of anodised aluminium by electroless method

In this investigation, a porous oxide coating has been formed on aluminium using direct current anodising technique, sensitised in stannous ion followed by colouring in dilute silver ion at different concentrations and durations to produce pleasing colours ranging from yellow to brown and black. The metallically coloured surface has been analysed using EDAX, atomic force microscopy, X-ray diffraction and ultraviolet–visible–infrared spectrophotometer, and a suitable mechanism has been proposed.

Rechargeable Antibacterial and Antifungal Polymeric Silver Sulfadiazines

Poly(methyl methacrylate) (PMMA)-based rechargeable antibacterial and antifungal polymeric silver sulfadiazines were prepared by copolymerizing acryloyl sulfadiazine with methyl methacrylate and sequentially treating the copolymers with dilute silver nitrate aqueous solutions. The chemical structures of the samples were characterized by FT-IR, 1H-NMR, XPS, and TGA analyses. On contact, the PMMA-based polymeric silver sulfadiazines provided 100% inactivation of 108—109 CFU/mL of Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria) in 10 min, and Candida tropicalis (yeast) in 30 min. Kirby—Bauer test data indicated that the antibacterial and antifungal effects were achieved through contact kill; no silver ions leached out of the new copolymers. The antibacterial and antifungal functions were stable for at least 12 months under normal storage conditions. Silver nitrate treatments regenerated any lost of antibacterial and antifungal activity; this recharging can be repeated as needed to achieve long-term protection. These properties make the new PMMA-based polymeric silver sulfadiazines attractive candidates for a broad range of medical (orthopedic), dental, and other related applications to reduce the risks of bacterial and fungal contamination on high-touch/high-risk surfaces and foreign body-related infections.

Microstructural Changes During Internal Oxidation of a Ag-Sn Alloy

AbstractElectrical contact materials are expected to combine improved mechanical and physical properties with good corrosion resistance at increased temperatures. One of the most widely used groups of contact materials are internally oxidized dispersion hardened silver alloys. The principle of their production involves selective oxidation of less noble solute elements (usually Mg, Al, Sn, Cd and Zn) forming the fine dispersion of oxide particles in the solvent silver matrix. In this study the internal oxidation of dilute silver alloy containing 2 at. % of tin was extensively investigated. The morphological evolution of the alloy and the internal oxidation kinetics were determined by several metallographic examinations and in-situ electrical resistance measurements in the air atmosphere and in the temperature range from 600°C to 800°C. The results of experiments and their analyses show that the microstructural changes during internal oxidation of Ag-Sn alloy are strongly dependent on the annealing temperature. At the highest temperatures the perfectly dispersive distribution of the oxide particles SnO2 in the silver matrix was found, while at lower temperatures the formation of inner oxide bands and distribution of oxide particles along the grain boundaries is predominate.

Visualization of the release behaviour of microcapsules

This paper describes an experimental technique that visualizes the release behaviour that microcapsules loaded initially with a halide salt experience when immersed in aqueous media. The technique, based on the principle of silver halide photography, involves observing the effect that contact with a dilute aqueous silver nitrate solution has on individual microcapsules. Rapid precipitation of an insoluble silver halide salt on a capsule surface provides a permanent record of the location(s) on a capsule surface at which halide ion release occurs. Results obtained by examining the behaviour of individual capsules selected from one KCl and three NaCl capsule samples produced by fluidized bed coating illustrate the wide variety of halide ion release behaviour exhibited by capsules from different capsule samples as well as capsules from the same sample. Scanning electron microscopy showed that halide ion release from all capsules studied does not occur uniformly over the capsule surface, but is limited to specific points on the capsule surface. Whereas most capsules from two NaCl samples broke open spontaneously after a short immersion time, thereby producing a large plume of AgCl precipitate, capsules from one NaCl and the KCl sample remained intact even after prolonged immersion. In these latter cases, a AgCl bolus typically grows on the surface of a capsule as immersion time increased.

Silver Nanoparticles from Ultrasonic Spray Pyrolysis of Aqueous Silver Nitrate

Silver particles less than 20 nm in diameter were synthesized by pyrolysis of an ultrasonically atomized spray of highly dilute aqueous silver nitrate solution at temperatures above 650°C and below the melting point of silver. Feed solution concentration and ultrasound power applied to the atomizer were found to have a significant impact on the particle size of the silver nanoparticles. Average particle size was found to be controllable in the range of 20 nm to 300 nm by varying the solution concentration and the ultrasound power to the atomizer.

Silver containing bioactive glasses prepared by molten salt ion-exchange

Bioactive glasses containing silver on their surface were produced by ion-exchange from dilute silver nitrate melts. This technique allowed introducing Ag+ ions only on the surface of the base glass while maintaining its bioactivity. The ion-exchanged glasses were characterized by means of X-Ray diffraction, SEM observations and compositional analysis (EDS). The control of the Ag+ content on the surface, as well as its diffusion profile throughout the ion-exchanged layer, was obtained by a careful choice of the ion-exchange parameters (temperature, time and silver concentration in the molten bath). A very good repeatability in the diffusion profile and in the silver concentration throughout the ion-exchanged layer was achieved. In vitro tests were performed on the ion-exchanged samples in order to verify their bioactive behavior (soaking in a simulated body fluid). On the soaked samples, the precipitation of a hydroxycarbonate apatite layer (HCAp) was investigated. The amount of released Ag+ into simulated body fluid from the exchanged glass was detected by atomic absorption spectroscopy with heated graphite furnace (GFAAS).

INFERENCE OF ELECTRON CONFIGURATION AND ACTIVATION ENERGY OF SOLUTE ATOMS IN COPPER AND SILVER CONDUCTORS ON ELECTROMIGRATION VOID FORMATION

It is shown that the kinetics of vacancy coagulation to macroscopic erosion voids in dilute crystalline metallic alloys depends strongly on the chemical nature of the solute element. In numerous published and the author's own electromigration data, it was found that the formation of erosion voids is suppressed if valence electrons of the matrix metal atom and the alloying (or impurity) atom sum up to an odd number. This is due to the formation and electronic charging state of vacancy-impurity pairs. Provided that activation energies of the solute elements are low compared to those of matrix atoms, stable vacancy-impurity pairs dominate and resist coagulation. At higher temperatures the number of pairs diminishes, weakening the mechanism of mutual Coulomb repulsion. Dilute copper and silver alloys are compared in the framework of the mentioned properties, giving copper a better chance for electromigration resistance than silver.

Determination of Absolute Vacancy Concentration and Vacancy-Impurity Interaction Energies in Dilute Silver and Copper Alloys

Determination of Absolute Vacancy Concentration and Vacancy-Impurity Interaction Energies in Dilute Silver and Copper Alloys

A differentiated silver intensification procedure for the peroxidase-diaminobenzidine reaction.

Several silver-based procedures have been developed to intensify the peroxidase-catalyzed diaminobenzidine polymer used as a marker in immunohistochemistry. Many of these methods use acutely unstable reagents or reagents that are not amenable to batch processing. We describe a new procedure with an initial treatment in dilute ammoniacal silver, followed by a differentiation step to remove background staining and a final toning in 0.2% gold chloride. The procedure provides a jet-black intensification of the tan diaminobenzidine product, is amenable to batch processing of free-floating sections and slide-mounted sections, and does not require acid-cleaned glassware.