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Atmospheric corrosion evaluation of silver coating using simulating technique test
, Article European Corrosion Conference: Long Term Prediction and Modelling of Corrosion, EUROCORR 2004, Nice, 12 September 2004 through 16 September 2004 ; 2004 ; Afshar, A ; Sharif University of Technology
2004
Abstract
A standard simulating technique test was investigated to assess the atmospheric corrosion behavior of silver coating. The rates of formation of corrosion products were measured in the simulating atmospheres of 100% humidity containing SO 2,H 2S and a complex atmosphere consist of SO 2,H 2S and NO 2 gases ,based on the mass increase method. The concentrations of corrosive gases were chosen according to real world conditions. XRD, SEM and EDS were used to examine the morphology and to determine the composition of the corrosion products under different experimental conditions. Results revealed the formation of Ag 2SO 4 and Ag 2S on the silver coating surfaces in the SO 2 and H 2S containing...
Reagent-free facile synthesis of silver nanoparticles/nanorods hybrid
, Article Proceedings of the IASTED International Conference on Nanotechnology and Applications, NANA 2010, 1 November 2010 through 3 November 2010, Cambridge, MA ; 2010 , Pages 498-501 ; 9780889868625 (ISBN) ; Soleyman, R ; Pourjavadi, A ; Sharif University of Technology
2010
Abstract
Silver nanostructures are very important agents in biomedical research, because of its unique activity against unfavorable processes in bioscience. In the current study, reagent-free facile preparation of silver nanoparticles (average diameter: 72 nm) and silver nanoparticles/ nanorods hybrid was reported via wet chemical synthesis method. Kappa-carrageenan (kC), a hydrophilic biopolymer with sulphate groups on its backbone, as capping agent was used in the reaction medium. Silver nanoparticles and silver nanoparticles/ nanorods formation was confirmed by SEM images. Further investigations were carried out using DLS data and GPC analysis
Investigation of metal absorption and antibacterial activity on cotton fabric modified by low temperature plasma
, Article Cellulose ; Volume 17, Issue 3 , 2010 , Pages 627-634 ; 09690239 (ISSN) ; Rashidi, A ; Ghoranneviss, M ; Anvari, A ; Rahimi, M. K ; Bameni Moghaddam, M ; Wiener, J ; Sharif University of Technology
2010
Abstract
In this work, the silver particle absorption and antibacterial activity of cotton fabric when modified by low temperature plasma were investigated. The modification consisted of plasma pre-functionalization followed by one-step wet treatment with silver nitrate solution. Oxygen and nitrogen were used as the working gases in the system, and the results were compared. The results showed that nitrogen plasma-treated samples can absorb more silver particles than oxygen-treated samples, and thus the antibacterial activity of the samples in this case, which was analyzed by the counting bacteria test, was increased considerably
Multistep reduction of oxygen on polycrystalline silver in alkaline solution
, Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 31, Issue 5 , 2010 , Pages 541-546 ; 02539837 (ISSN) ; Gobal, F ; Mahjani, M. G ; Hosseini Aliabadi, M ; Sharif University of Technology
Abstract
Oxygen reduction on a polycrystalline silver electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The reaction occurred by a two-electron pathway. The steps in the mechanism were observed in the cyclic voltammograms recorded with different scan rates. The intermediates formed in the steps were detected by electrochemical impedance spectroscopy
Electrical conductivity of methylimidazolium hexafluorophosphate ionic liquid in the presence of colloidal silver nano particles with different sizes and temperatures
, Article Journal of Physical Chemistry C ; Volume 121, Issue 39 , 2017 ; 19327447 (ISSN) ; Kiani, S ; Sharif University of Technology
American Chemical Society
2017
Abstract
Colloidal nanoparticle could be used for recognition location of tumors and cancer tissue. A simulation of molecular dynamic for colloidal silver nanoparticles (Ag NPs) based on density functional theory (DFT) potential parametrization with different sizes in 1-ethyl-3-methylimidazolium hexafluorophosphate [EMim][PF6] ionic liquid was performed. Then, using Green Kubo formalism, diffusion coefficient for Ag NPs in IL and in the gas phase was calculated. We also calculated diffusion coefficients of anions and cations for pure IL and IL in the presence of different sizes of Ag NPs at different temperatures. The findings showed that the diffusion coefficient of anions and cations increases in...
Design and Fabrication of Nanovolt Ag/AgCl Bio-potential Sensor
, M.Sc. Thesis Sharif University of Technology ; Fardmanesh, Mehdi (Supervisor) ; Simchi, Abdolreza (Co-Advisor)
Abstract
Biopotential sensors are used in a wide range of biomedical applications. For example, measuring electric potentials on the surface of living tissues in electroencephalography (EEG), electromyography (EMG), and electrocardiography (ECG) systems in which the brain, muscle, and heart activities respectively are measured over time. Moreover, these electrodes are used in measuring the pH of different materials and also in receiving and recording the electric field changes of the environment. The major purpose of biopotential electrodes is to act as a transducer between the ionic transport of the tissue and the electron flow in the electrode. Such a transduction takes place due to an oxidation or...
Design and Fabrication of Electrical Field Sensor for Biological and Corrosion Currents Application
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor) ; Fardmanesh, Mehdi (Supervisor)
Abstract
Electric field sensors are one of the common types of sensors that are widely used today to record changes in the electric field in underwater environments, also record pH changes in different materials. This type of sensor is inspired by the shark mucous membrane. In this study, silver / silver chloride silver (Ag / AgCl) was used for three methods of silver filtration directly in electrolyte containing chloride ion, Electrophoretic electrode method and electrode making method using silver oxide adhesive. Part of the electrodes manufacturing method involves converting part of silver into silver chloride. The made electrode has a length of 7 cm and a diameter of 0.5 mm, with its core made of...
Silver Nanowaste Reduction and Recycling by Combination of Physical and Chemical Seperation Methods
, M.Sc. Thesis Sharif University of Technology ; Hormozi Nezhad, Mohammad Reza (Supervisor) ; Sajjadi, Ali Akbar (Supervisor)
Abstract
The increasing utilization of silver nanoparticles (Ag-NPs) in industrial and consumer products has raised concern to wastewater treatment utilities, due to its antimicrobial activity. In this research, recovery of silver nanoparticles from wastewater via using activated carbon and convert it into usable nanoparticles is presented. real waste of silver nanoparticles have been used and activated carbon as adsorbent has a high absorption recovery for silver. Under the optimized experimental parameters e.g. pH, temperature, time of process, and amount of activated carbon, an absorption maximum was achieved and over than 99% of silver nanoparticles can be removed from wastewater. After the...
Aggregation-based colorimetric sensor for determination of prothioconazole fungicide using colloidal silver nanoparticles (AgNPs)
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 187 , 2017 , Pages 143-148 ; 13861425 (ISSN) ; Fahimi Kashani, N ; Hormozi Nezhad, M. R ; Sharif University of Technology
Abstract
There is a growing interest in developing high-performance sensors monitoring fungicides, due to their broadly usage and their adverse effects on humans and wildlife. In the present study, a colorimetric probe has been proposed for detection of prothioconazole based on aggregation of unmodified silver nanoparticles (AgNPs). Under optimized condition, linear relationships between the concentration of prothioconazole and the absorbance ratio of A500/A395 were found over the range of 0.01 μg·mL− 1 to 0.4 μg·mL− 1 with quantification limit as low as 1.7 ng·mL− 1. Furthermore, AgNPs color change from yellow to pink-orange in presence of prothioconazole, indicates highly sensitive naked-eye...
Silver nanoparticles immobilized onto poly(4-vinylpyridine)-functionalized magnetic nanoparticles: a robust magnetically recyclable catalyst for oxidant-free alcohol dehydrogenation
, Article Applied Organometallic Chemistry ; Volume 32, Issue 2 , February , 2018 ; 02682605 (ISSN) ; Shakourian Fard, M ; Talebloo, N ; Mahmoodi Hashemi, M ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
A heterogeneous and recyclable catalyst with a high loading of silver nanoparticles was synthesized via the silver nanoparticles being supported onto the surface of magnetic nanoparticles coated with poly(4-vinylpyridine). The synthesized catalyst was used in the dehydrogenation of alcohols to corresponding carbonyl compounds. A broad diversity of alcohols was converted into their corresponding carbonyl compounds in excellent yields. The catalyst was easily recovered by applying an external magnetic field and reused for seven reaction cycles without considerable loss of activity. The catalyst was fully characterized using various techniques. Copyright © 2017 John Wiley & Sons, Ltd
Five- and six-coordinated silver(I) complexes formed by a metallomacrocyclic ligand with a “Au2N2” donor group: observation of pendulum and linear motions and dual phosphorescence
, Article Inorganic Chemistry ; Volume 59, Issue 8 , 31 March , 2020 , Pages 5702-5712 ; Jamali, S ; Jamjah, A ; Shakirova, J. R ; Tunik, S. P ; Gurzhiy, V ; Samouei, H ; Shahsavari, H. R ; Sharif University of Technology
American Chemical Society
2020
Abstract
The six-coordinated silver(I) complex [Au2Ag(μ-(PPh2)2py)2(OTf)2](OTf), 4 (py = pyridine, OTf = CF3SO3), and the five-coordinated silver(I) complex [Au2Ag(acetone)(μ-(PPh2)2py)2](PF6)3, 6, were prepared by the reaction of the precursor complexes 1(OTf)2 and 1(PF6)2, in which 1 = [Au2(μ-(PPh2)2py)2]2+, with 1 equiv of Ag(OTf) in dichloromethane and excess of Ag(PF6) in a mixture of dichloromethane/acetone, respectively. Also, the five-coordinated silver(I) complex [Au2Ag(μ-(PPh2)2py)2(py)(OTf)](OTf)2, 5, was obtained by the reaction of 4 with pyridine. The clusters 4-6 were characterized using multinuclear NMR spectroscopy and elemental microanalysis. The single-crystal X-ray diffraction...
An Investigation on Production of Silver Nanopowder by Electromagnetic Levitation Melting Method
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
Electromagnetic levitation gas condensation (ELGC) method was used to synthesize silver nanoparticles. Silver droplets were melted and levitated stably at about 1130 °C with appropriate flat coils in a 10 mm OD silica tube. High purity argon, nitrogen and helium were employed as carrier gases and cooling media. Morphology and particle size of the products were investigated by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD) energy dispersive X-ray analysis (EDAX) and dynamic light scattering (DLS). The DLS, SEM and TEM studies demonstrated narrow size distribution of spherical shape Ag nanoparticles with particle size of about 60, 45 and 35 nm synthesized...
Thesis Title Synthesis and Characterization of Metal Nano Oxids and Investigation of their Catalytic Activity
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
In this project, the catalytic properties of CuO and ZnO were investigated in reduction reactions.MOFs were used as a precursor to preparation of these metal oxides. Gold and silver nanoparticles were used to improve the catalytic properties of the prepared metal oxides. Structural characteristics of nanocatalysts were stydied by SEM, TEM, XRD and FT-IR techniques. The prepared nanocomposites were applied in the catalytic reduction of paranitrophenol in the presence of sodium borohydride and the kinetics and mechanism were investigated according to the structure of the prepared catalysts
Biopolymers Mediated Green Synthesis of Silver Nanoparticles With Definite Shape and Their Biomedical Activity Investigation
, M.Sc. Thesis Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
Silver nanoparticles (Ag-NPs) are promising agents in bionanotechnology, because of their unique activity against unfavorable processes in bioscience such as undesirable microbial growth, angiogenesis in tumors and etc. Ag-NPs have been widely used in wound dressing; wound healing, water treatment filters, inks, sensors, catalysts, cosmetics, orthopaedics, surgical instruments and vascular prosthesis. Ever-increasing applications of Ag-NPs in biomedical field are due to the anti-bacterial, anti-fungal, anti-viral, anti-platelet, anti-proliferative, anti-inflammatory (apoptosis detection) and anti-angiogenesis properties (cancer therapy). In the current research, we synthesized Ag-NPs in...
Synthesis of Colloidal Silver Nanoparticles by Microwave Method and Study of its Antibacterial Activity
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
Silver nanoparticles are widely used in different industries because of their antibacterial effects. Many synthesis methods were used to obtain silver nanoparticles. In this study the microwave method is used to synthesize nanosilver. This method is easier and faster in comparison to other methods. The effect of precursors’ concentrations, using different solvents, different remaining time in microwave and microwave power were studied. By increasing the reaction time, microwave power and using different solvents, nanosilver particle size varies from 2 nm up to 300nm. The TEM images, size distribution, XRD patterns and UV-visible spectrum are shown. The obtained nanosilver was used to observe...
Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique
, Article Journal of Nanoparticle Research ; Volume 16, Issue 9 , September , 2014 ; ISSN: 13880764 ; Dolati, A ; Sharif University of Technology
Abstract
Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO...
Highly efficient hydroxyapatite/TiO2 composites covered by silver halides as E. coli disinfectant under visible light and dark media
, Article Photochemical and Photobiological Sciences ; Volume 12, Issue 10 , 2013 , Pages 1787-1794 ; 1474905X (ISSN) ; Elahifard, M ; Haghighi, S ; Gholami, M ; Sharif University of Technology
2013
Abstract
TiO2-based photocatalysts are seen as the most common agents for the photodegradation of bacteria. In this study, AgCl/TiO2, hydroxyapatite(Hp)/AgCl/TiO2, AgI/TiO2, and Hp/AgI/TiO2 were prepared by the deposition-precipitation method on P25 TiO2 nanoparticles and were characterized by XRD, SEM, FT-IR, EDX and BET methods. The prepared composites showed high efficiency for the inactivation of Escherichia coli (E. coli) bacteria under visible light and in dark media with different catalyst amounts of 12 and 24 mg, respectively. In less than 30 min, AgI/TiO2, prepared by the combination of cationic surfactant and PVPI2, disinfected 1 × 107 colony-forming units of E. coli completely. However,...
An Investigation on the Effects of Experimental Variables on Silver Nano Particles Produced by Electromagnetic Levitation Technique
, Article Journal of Cluster Science ; Volume 24, Issue 3 , 2013 , Pages 635-642 ; 10407278 (ISSN) ; Malekzadeh, M ; Sharif University of Technology
2013
Abstract
In this study the effects of melt temperature and flow rate of cooling gas on the characteristics of silver nanoparticles have been studied. Transmission electron microscopy and dynamic light scattering techniques have been employed to monitor morphology and particle size of the product. Measurements reveal that higher melt temperatures and higher cooling gas flow rates can decrease particle size. Silver nanoparticles with an average particle size of 35 nm and specific surface of 18.489 m2/g have been obtained at a melt temperature of 1,130 °C with argon flow rate of 20 liters per minute
Silver Block Intersection Graphs of Steiner 2-Designs
, Article Graphs and Combinatorics ; Volume 29, Issue 4 , 2013 , Pages 735-746 ; 09110119 (ISSN) ; Besharati, N ; Mahmoodian, E. S ; Mortezaeefar, M ; Sharif University of Technology
2013
Abstract
For a block design D, a series of block intersection graphs G i, or i-BIG(D), i = 0,..., k is defined in which the vertices are the blocks of D, with two vertices adjacent if and only if the corresponding blocks intersect in exactly i elements. A silver graph G is defined with respect to a maximum independent set of G, called an α-set. Let G be an r-regular graph and c be a proper (r + 1)-coloring of G. A vertex x in G is said to be rainbow with respect to c if every color appears in the closed neighborhood N[x] = N(x) ∪ {x}. Given an α-set I of G, a coloring c is said to be silver with respect to I if every x ∈ I is rainbow with respect to c. We say G is silver if it admits a silver...
A sensitive colorimetric detection of ascorbic acid in pharmaceutical products based on formation of anisotropic silver nanoparticles
, Article Scientia Iranica ; Volume 17, Issue 2 F , 2010 , Pages 148-153 ; 10263098 (ISSN) ; Karimi, M. A ; Shahheydari, F ; Sharif University of Technology
2010
Abstract
A sensitive colorimetric method for the detection of ascorbic acid was proposed in this research based on the reduction of silver ions by ascorbic acid in the presence of citrate-stabilized silver seeds, additional trisodium citrate and a polymer such as polyvinylpyrrolidone. The color of the stable sol is controlled by varying the concentration of trisodium citrate (TSC), polyvinylpyrrolidone, silver nitrate and silver seeds. The reduction of Ag + to triangle silver nanoparticles (Ag-NPs) by ascorbic acid in the presence of trisodium citrate (TSC) and silver seeds produced two very intense surface plasmon resonance peaks of Ag-NPs. The plasmon absorbance of Ag-NPs allows the quantitative...