Sharif Digital Repository

The growing use of nanomaterials leads to causing harm to the aquatic environment resulting in a demand for effective methods to remove these nanomaterials from aquatic environment. On the other hand, the high cost of raw materials used for the production of noble metal nanomaterial limits their use or requires the development of recycling and recovery methods. In this study, we found that citrate capped gold nanoparticles (cit-AuNPs) could be removed effectively from waste water using aluminum chloride (AlCl3) coagulant. The effect of pH, of coagulant concentration, and alkalinity on the performance of this coagulant was investigated. It has... 

In this study, a multivariate-based strategy was developed for simultaneous determination of thirteen carcinogenic polycyclic aromatic hydrocarbons (PAHs) in water samples using gold nanoparticles (AuNPs) as solid-phase extraction (SPE) sorbent combined with gas chromatography-flame ionization detector (GC-FID). The extraction technique is based on the strong affinity between citrate capped AuNPs and PAHs. Furthermore, characterization of AuNPs was performed by UV-Vis and TEM techniques. A rotatable central composite design (CCD) combined with multiple linear regression (MLR) was used for designing the extraction procedure and developing models using the GC peak areas of 13 PAHs. Also,... 

Aspect ratio dependant optical properties of silver and gold nanorods is responsible for great attention toward controlling the aspect ratio of this class of the nanostructure for their application in variety of area, such as medical diagnosis, drug delivery, biosensing and treatment. In this research, gold and silver nanorods have been synthesized using chemical reducation and growth based on seed mediated method, which is the newest and one of the best methods with less difficulty for producing silver and gold nanorods. Absorption of the visible light by gold and silver nanorods results in appearing the longitudinal and transverse Plasmon bands in their absorption spectra which is related... 

This present work is an introduction of a new electrochemical sensor toward the determination of biomolecule. A simple electrodeposition method was employed to construct a thin film modifier of palladium–gold nanoparticles (Pd–AuNPs) decorated multi-walled carbon nanotube (MWCNT) on the surface of glassy carbon electrode (GCE). Morphological characterization of the modified electrode was performed by the scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and cyclic voltammetry (CV) techniques. This nanostructured film modified electrode effectively exhibited enhanced properties for the detection of ceftazidime (CFZ). The effects of various experimental variables such... 

Gold Coin Futures Market by contract delivery month of Dey, in 1387 as part of the capital market in Iran Mercantile Exchange started its activities. Each transaction in this market includes ten coins all gold (tamam bahar). Nowadays We have three symbols on each of the next three months are traded in an active market. In this market, any natural or legal person giving the guarantee fund with any of the agencies approved by the Stock Organization and in the terms of seller or buyer begin their trading. For transactions in order to succeed, we need to predict the rise or fall of prices to be a buyer in the rises and be seller in the falls. With considering the performance of Neural Networks... 

Prediction is an important issue in many areas. Proper planning for the future requires careful forecasting, so providing accurate methods, especially in the financial field, is invaluable. In this study, the main problem is predicting the price of global gold. Factors for gold prices include oil, gas, silver, soybeans, copper, the s & p500 index, the Dow Jones index, the British and Japanese stock market indices, the dollar index, the multi-currency exchange rate (pound-euro-yuan-yen) with the dollar to The title of the influential factors in this research is considered. The time frame of this research is daily, in other words, the data is collected on a daily basis and the goal is to... 

An efficient method has been developed to synthesize well-aligned multi-walled carbon nanotubes (MWCNTs) on a conductive Ta substrate by chemical vapor deposition (CVD). By varying CVD parameters, aligned CNTs (A-MWCNTs) with diameter between 20-100 nm and length of some micrometers with bamboo-like shapes were produced. Free-standing MWCNTs arrays were functionalized and purified through electrochemical oxidation. Then in order to improve the performance, facile template-free electrochemical routes were developed for the shape-selective synthesis of less-common Au nanostructures, including flower, sphere, dendrite, sheet and rod on A-CNTs at room temperature. The results showed that the... 

Gold coatings due to their unique properties, use in a wide range of applications.Decorative coatings of gold for centuries, has been considered.However, few studies have been done on the properties of this metal, this metal is shown not only in terms of decorating, but in the industry also has a wide range of applications. In this project non-cyanide electroless bath based on binary complex sulfite-thiosulfate was prepared and metal ion concentration of the complex components, temperature, time, pH and addition of amino acids, optimzed bystability, qualityand rate of coating. The main aim of optimizing bathsis optimize the thickness and appearance of the coating.It was found that by... 

Application of nanoparticles in targeted delivery and controlled drug release is recently highly attracted especially in cancer therapy. In this study with the aim of developing a novel drug vector based on metallic nanoparticles, gold nanoparticles with their unique characteristics were used to design a vector for targeted anti-cancer drug delivery to tumor. First, gold nanoparticles were chemically synthesized therough sodium citrate and sodium brohydrate reductions with average diameters of 22 and 11 nm, respectively. Then, the activated poly ethylene glycol (PEG) and activated folic acid were conjugated to the lysine-capped gold nanoparticles. Subsequently, the widely used anticancer... 

In recent years, many studies have conducted research about stem cells due to their prominent features such as proliferation and differentiation. By changing the specific parameters of the cellular micro-environment, it is possible to determine the stem cells fate and thereby use them in medical affairs. For this purpose, various devices and methods have been designeds such as microfluidic devices and scaffolds. The microfluidic devices has been especially focuced in the researchs due to their unique features, like the possibility of testing with small amounts of samples, the creation and control of low cost cellular micro-environment and low practical time. Two-dimensional scaffolds made up... 

Cancer treatment is one of the most challenging issues of recent years. Extensive researches have been conducted in various fields of medicine, pharmacy, and medical physics in this regard. Today, considering nanotechnology developments, researchers believe that full cancer treatment is possible through the use of nano-systems designed with scientific background to overcome the defects of previous methods. In this research, the main purpose is to design and synthesize multifunctional hybrid nanostructures with favorable optical and magnetic properties providing a way to combine chemotherapy and thermal treatment. Accordingly, two different structures were designed and experimentally... 

Selective oxidation of cyclohexene and styrene were investigated using molecular oxygen under mild conditions. Au/TiO2 and Au/Al2O3 surfaces were impregnated with three different Ionic Liquids. Supported Ionic Liquids gold nanocatalysts are particularly versatile catalysts for oxidation reaction with exceptionally high efficiency and significant selectivity.
Selective oxidation of alkenes by hexadecyl-trimethyl-ammonium bromide-stabilized gold nanorods and gold nanosphere were investigated using molecular oxygen in aqueous solution under mild conditions. Colloidal gold nanoparticles are particularly versatile catalysts for oxidation reaction with exceptionally high efficiency and... 

In the first part of this work, citric acid monomer was selected to produce dendrimer through the divergent method using logical conditions (for controlling its functional groups) on the base of poly (ethylene glycol) as the core. Triblock copolymers (ABA-type) of citric acid and poly (ethylene glycol) (PCA-PEG-PCA) as biocompatible compounds were synthesized in four different molecular weights and applied as nanocarriers. The structure definition of the molecules and nanoparticles were carried out using different spectroscopy methods. Diameter of the synthesized copolymers was investigated using dynamic light scattering (DLS) experiments and transmission electron microscopy (TEM) and it was... 

This study intends to evaluate Value at Risk of the Gold price returns for Short and Long positions by using Extreme value, Normal and t-student parametric model approaches. Conditional variance also is estimated by GARCH(1,1), FIGARCH, FIEGARCH, PGARCH, EGARCH and TGARCH with the three window sizes: 1000, 750 and 500. Accuracy and sufficiency of specified models are tested in two stages. In the first stage we select the models which are sufficient and in the second stage, a loss function is calculated for the VaR methods which passed the sufficiency tests. Our result shows that the accuracy ranking is not independent on window size. Nevertheless, the most accurate models are those which use... 

Textual news published in the media on a daily basis is a large and valuable source of unstructured data that can be used to analyze and model the financial market by using text mining methods. The purpose of this study is to design a news-reading system for economic analysis and modeling of gold prices using features extracted from textual news and text mining methods; it seeks to enable the machine to read news like financial analysts then analyze and forecast the economic situation and market trends. For this purpose, we collected news from the website of an Iranian economic news agency. To design the economic analyzer, we extracted important economic, political, and social factors from... 

This research aims to expand comprehensive information about bioleaching of different kinds of electronic waste (E-waste). The selected wastes were computer PCBs (CPCBs), mobile phone PCBs (MPPCBs), television PCBs (TVPCBs), fax machine PCBs (FPCBs), copy machine PCBs (COPCBs) and central processing units (CPUs). At the first step, a comprehensive study made on the E-waste structure. The best method for precious metal digestion analysis introduced, i.e., using aqua regia, hydrogen peroxide, hydrofluoric acid, and boric acid. The economic values of the E-wastes were as follows: CPU> MPPCBs> COPCBs> FPCBs> CPCBs> TVPCBs. Among the metals, gold attributed to the highest value distribution and... 

In this work, a new catalyst based on gold nanoparticles immobilized on magnetic GO (graphene oxide) has been introduced. A new ligand based on pyridine has been used to the functionalization of GO to design robust heterogeneous catalyst for reduction in a short time using a low amount of the catalyst. The prepared catalyst was employed in the synthesis of aromatic amines using various types of nitroarnes in water. This catalyst is readily prepared from available starting materials and also is a reusable catalyst having very good stability to air and moisture. The proposed procedure applied here can conduct the reactions under milder reactions. Finally, due to total removal of the... 

The first report of anti-aggregation-based sensor arrays is presented. The strategy is based on the competitive interaction of citrate-capped gold nanoparticles (AuNPs) and heavy metal ions (i.e., Hg(II), Ag(I), Fe(III), and Pb (II)) with three aggregation reagents (i.e., cysteine, melamine, and arginine). In the presence of aggregation reagent,the color and UV–vis spectra of AuNPs are changed indicating the aggregation ofAuNPs. Addition of the aggregation reagents which are firstly treated with the ions, causes AuNPs turn from the aggregation to the dispersion state. The anti-aggregation capability of ions towards various aggregation reagents is different because of distinct stability... 

Biological thiols are crucial substances that play an essential role in several biological processes and activities in the body. Hence, the fluctuation of their concentrations can be used as a diagnostic sign for numerous disorders. In contrast, the ratio of these thiols to their disulfide form within the cell is useful as an indicator for determining cytotoxicity. Hence, it is crucial for develop a simple yet efficient analytical technique for quickly recognizing and determining them. The purpose of this study is to develop a plasmonic colorimetric sensor by utilizing gold nanorods (AuNRs). This sensor aims to accurately measure and distinguish between cysteine (CYS) and glutathione (GSH),... 

Detection of pentaerythritol tetranitrate (PETN) as an explosive has been of great interest because of public safety and military concerns. Here, we have presented a simple, selective and sensitive colorimetric method for direct detection of PETN. The gold nanoparticles (AuNPs) were first exposed to arginine which has primary amines in its structure. Primary amines from arginine as electron donors could strongly interact with electron deficient –NO2 group of PETN. Also, hydrogen bonding could happen between the –NO2 group of PETN and –NH2 group of arginine molecules. Therefore, selective aggregation of AuNPs happened because of the donor-acceptor and hydrogen bonding interactions. Due to the...