Producing gold nanoparticles from loaded activated carbon and its separation with carbon fiber film formation at the oil/water interface in the acetone- water-sodium chloride system

Abstract Due to the wide spread applications of gold in medicine, electronic computational industries, catalysts, and its special application in biological researches and more over by attention to high cost and complicated production of gold nanoparticles (AuNPs) and in the other hand, the importance of substituting the environmental pollutants such as cyanide compounds in most commonly processes of gold recovery from ores and concentrates, finding a simple, economic and environmental way to achieve AuNPs has to be considered. Because of its large surface area, activated carbon (AC) is used in extracting gold. In this research work a new way has been mentioned for production and separation of AuNPs from loaded AC. By heating loaded AC in the air at 300 for 30 min, gold metal nanoparticles were produced on the surfaces of AC with reducing the gold cyanide complex. The detachment of the AuNPs from AC surfaces was done by two ways: 1. Abrasion of AC by NaCl 2. Using ultrasound; the separation of the detached AuNPs from AC granules abraded by NaCl was done based on the difference between AC and gold density and using water and oil mixture. Effect of abrasion time, salt to carbon weight ratio and prewashed loaded AC conditions on the amount of gold recovered from loaded AC was evaluated in abrasion method. In a novel approach, separation of carbon from gold-containing aqueous solution was done by addition of acetone in mixture and forming carbon microfibers film at the oil/water interface. Acid washing was done to remove impurities after separating carbon from gold-containing solution. As a result, relatively pure AuNPs were obtained after acid washing

TECHNICAL NOTE CHARACTERIZATION OF CONSTRAINED AGED NiTi STRIPS FOR USING IN ARTIFICIAL MUSCLE ACTUATORS

Abstract Marvelous bending/straightening effects of two-way shape memory alloy (TWSMA) help their employment in design and manufacturing of new medical appliances. Constrained ageing with bending load scheme can induce two-way shape memory effect (TWSME). Scanning electron microscopic (SEM) analysis, electrical resistivity measurement (ERM) and differential scanning calorimetry (DSC) are employed to determine the property change due to flat strip constrained aging. Results show that flat-annealing prior to the aging shifts NiTi transformations temperatures to higher values. Superelastic behavior of the as-received/flat-annealed/aged samples with more adequate transition temperatures due to biological tissue replacement is studied by three-point flexural tests. Results show that curing changes the transition points of the NiTi strips. These changes affect the shape memory behavior of the NiTi strips embedded within the biocompatible flexible composite segments

Precipitation and Effect of Applied Surfactant on Distribution of Particle Size

Production of NiO by chemical precipitation is the approach utilized in this work. Materials mainly used in this project are nickel nitrate hex hydrate (as a basic material), sodium hydroxide (as a precipitator material), and the following surfactants (for reduction in particle size). Applied surfactants are in two kinds: polymeric (PVP, PEG) and cationic (CTAB) surfactants, 1.0 gram. Nanopowders properties are identified by TG, FTIR, XRD, SEM, and TEM. The results obtained confirm the presence of nickel oxide nanopowders produced during chemical precipitation

PARTICLES SIZE DISTRIBUTION EFFECT ON 3D PACKING OF NANOPARTICLES INTO A BOUNDED REGION

Abstract In this paper, the effects of two different Particle Size Distributions (PSD) on packing behavior of ideal rigid spherical nanoparticles using a novel packing model based on parallel algorithms have been reported. A mersenne twister algorithm was used to generate pseudorandom numbers for the particles initial coordinates. Also, for this purpose a nanosized tetragonal confined container with a square floor (300 * 300 nm) were used in this work. The Andreasen and the Lognormal PSDs were chosen to investigate the packing behavior in a 3D bounded region. The effects of particle numbers on packing behavior of these two PSDs have been investigated. Also the reproducibility and the distribution of packing factor of these PSDs were compared. Keyword

Facile synthesis of monodisperse thermally immiscible Ag-Ni alloy nanoparticles at room temperature

Abstract. Ag and Ni are immiscible, mainly due to their large lattice mismatch. This paper reports on their nanoscale formation of solid solution at room temperature by simple reduction reactions which lead to the amorphous Ag-Ni alloy nanoparticles (ANPs) with mono-disperse distribution. Microscopic and spectroscopic studies confirmed dependence of the alloy composition on size of nanoparticles. In the presence of different ligands such as sodium citrate, polyvinyl alcohol and potassium carbonate a mixture of silver oxide and Ag-Ni ANPs was achieved. Stoichiometry of the Ag-Ni ANPs was also found to be strongly dependent on ligands of the reduction reaction and further study shows without any ligand 100% Ag-Ni ANPs was observed in the system. Using Tetrakis hydroxymethyl phosphonium chloride resulted in construction of near-uniform ANPs in the easily controllable conditions of the present alloying procedure. Nanoparticles having up to 65% Ni were observed for the first time in this research

Structural and Physical Properties of TiO2/CNT Nanocomposite Thin Films Synthesized by Sol-Gel Dip Coating Method for Using in Dye-Sensitized Solar Cell

TiO2/MWCNT nanocomposite thin films containing different percentages of multi-walled carbon nanotubes were coated on fluorinated tin oxide substrates by sol-gel dip coating method. Results of X-ray diffraction analysis indicated that the crystal structure of the coatings was anatase TiO2. It was also understood that the size of crystallites reduced with CNT but structural properties and equilibrium phase remain intact. Field emission scanning electron microscope images showed that CNTs dispersed uniformly among 45 nm spherical TiO2 particles of close relations. These images also showed that CNT promoted cracks on the coated surface. Results of the UV-Vis spectroscopy showed that the visible light range adsorption  increased with CNT and the absorption edge did not significantly differ with the pure TiO2 layers.. Results of the photoluminescence spectroscopy revealed that the presence of CNT could reduce the pair electron–electron holes recombination which is considered totally undesirable. &nbsp

Fabrication and Characterization of NiTi-based Shape Memory Thin Films

Abstract NiTi-based shape memory thin films have attracted much attention in recent years as intelligent and functional materials in the rapidly growing field of Micro-ElectroMechanical-Systems (MEMS) and Bio-MEMS. In this paper the fabrication of NiTi and NiTiHf thin films by a DC magnetron sputtering using simultaneous deposition from elemental targets is reported. The characterization of the films were performed using a differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) to explore transformation temperatures and structure as a function of film composition. The results showed that film composition is a critical issue to control transition temperatures. The proposed technique can be considered as a flexible fabrication method to control precise film composition, which leads to manufacturing of shape memory microactuators in a wide range of applications

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Abstract-Presence of bubbles affects quality of the lead silicate glass (LSG) samples. This paper presents the most recent results obtained on formation and collapse of bubbles in LSG melts. Main sources of the bubbles are dissolved gases and redox reactions. A foamy layer full of bubbles rapidly forms at top of the molten phase. Effect of viscosity and density of the melt on content and ascension rate of the bubbles are investigated. Num ber and mean diameter of the bubbles and thickness of the top bubbly layer are calculated from gas volume measurements and image analysis via J software

Synthesis of nano-hydroxyapatite under a sonochemical/hydrothermal condition

In this study, hydroxyapatite (denoted as HAp) nanostructure with uniform morphologies, controllable size, nano-dispersion and narrow size distribution in diameter has been synthesized successfully by low-temperature hydrothermal process, and the as-synthesized powders were characterized by XRD, scanning electron microscopy, high-resolution transmission microscopy, FT-IR, Zetasizer and inductively coupled plasma. In the present work, a novel sonochemical technique using CaHPO4·2H2O/NaOH/distilled water with cetyltrimethylammonium bromide ((CH3(CH2) 15N+(CH3)3Br-) designated as CTAB) under a hydrothermal condition to synthesize HAp nanostructure was described. Furthermore, the usage of a high basic condition and a water environment are the two crucial keys in ensuring the formation of HAp in the hydrothermal/sonochemical processes. However, the crystallite size and crystallinity degree of the HAp increased with increasing annealing temperature. Indeed, the present work will introduce a new method in synthesizing HAs for scientific and medical engineering

Hydrothermal synthesis of aligned hydroxyapatite nanorods with ultra-high crystalinity

Hydroxyapatite nanorods aligned with ultrahigh crystallinity and high-yield were successfully synthesized through a hydrothermal approach. In this experiment, a new composition of cetyltrimethylammonium bromide ((CH3 (CH2 )15N + (CH3 )3Br - ) was designated as CTAP)/Ca(NO3 )2 / (NH4)2HPO4/NaOH and distilled water under hydrothermal condition, to synthesize single crystal HAp nanorods with diameter of 20 ± 10 nm and length of 80 ± 20 nm, was introduced. Crystal phases were determined by X-ray diffraction (XRD). Scanning electron microscope (SEM) was applied to investigate the morphology. The microstructure of the HAp products were further observed by transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) with energy-dispersive X-ray spectroscopy (EDX). The purity and chemical composition of the as-synthesized powder was analyzed by FTIR and inductively coupled plasma atomic emission spectroscopy (ICP)