Sharif Digital Repository

The main strategy for treating solid cancers is based on the very early diagnosis of a malignant tumor, and in general the smaller the tumor, the greater the likelihood of successful treatment. Magnetic Resonance Imaging (MRI), based on the nuclear magnetic resonance phenomenon, provides the possibility of detecting early malignant tumors with the assistance of appropriate contrast agents. Hence, researchers continue to develop novel magnetic materials to achieve this aim. Superparamagnetic nanoparticles have become the focus of these studies because their superparamagnetic, biocompatible and hydrophilic properties would be revealed after modifying the particle surface by suitable... 

ZnFe2O4 nanoparticles have been successfully prepared through a controlled microwave–assisted co-precipitation as well as conventional co-precipitation. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were used for the structural, morphological and magnetic investigation of the product. Average particle size was obtained as 12 nm from XRD. Catalytic activity of ZnFe2O4 nanopowder for O-acylation of alcohol and phenol has been investigated. A trace amount of ZnFe2O4 has been effectively used as a nanocatalyst for the acylation of alcohol and phenol in acetic anhydride.

 

A biocompatible ferrofluid have been prepared by co-precipitation of FeCl2.4H2O and FeCl3.6H2O under ultrasonic irradiation and with NaOH as alkaline agent. Also cystein was used as capping agent in the solution. Magnetic properties of the produced ferrofluid then determined by VSM test and magnetite nanoparticles were characterized by XRD and TEM techniques. Results indicate the presence of a biocompatible superparamagnetic ferrofluid including magnetite nanoparticles with particle size ranging under 15 nm. The effect of ultrasonic irradiation on presence of a sharp particle size distribution then denoted by comparing the condition with production without ultrasonic irradiation  

Microemulsion is one of the major processing techniques to synthesize a nano, homogeneous, and almost agglomerate-free powders. Any kind of oxide ceramics such as piezoelectric ceramics can be synthesis via this method in nano scale without the formation of any intermediate phase. In this study, Lead zirconate titanate (PZT) powders with composition near the morphotropic phase boundary (MPB) have been synthesized via a microemulsion processing route. This emulsion system is a thermodynamically stable mixture of oil (cyclohexane), nonionic surfactant (Triton X100), and an aqueous solution containing specific amount of Pb2+, Zr4+ and Ti4+. The ratio of these ions was adjusted with using ICP.... 

A biocompatible ferrofluid containing ?Fe?_3 O_4 nanoparticles was produced using co precipitation of ?FeCl?_2.?4H?_(2 )O and ?FeCl?_3 ?6H?_2 O under ultrasonic irradiation power with NaOH being the alkaline. Two variables studied in this research were concentration and molecular weight of PEG, as the coating agent. The impact of these variables were carefully monitored on shape, size distribution and magnetic behavior of nanoparticles through SEM, DLS, XRD and VSM characterization techniques. Moreover, MRI relaxation times,T_1and T_2, were calculated using synthesized nanoparticles as contrast agents. Accordingly these nanoparticles were biologically evaluated by MTT assay. Results... 

Present study is designed to determine the effect of manganese content in primitive inverse spinel structure of iron oxide nanoparticles. PEG coated water base ferrofluids of Mnx¬Fe3-xO4 (0<0>1)nanoparticles were prepared by co-precipitation method in presence of nitrogen gas and ultrasonic waves using NaOH as a base for biomedical purposes. The crystallite size and structure of synthesized nanoparticles were studied using atomic absorption spectroscopy (AAS), X-ray diffraction spectrometry (XRD), field emission scanning electron microscopy (FE-SEM) and dynamic light scattering (DLS) methods. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) were used to... 

Ferrofluids are special stable suspensions of magnetic nanoparticles dispersed in liquid phase. These materials have numerous biological applications such as drug delivery, magnetic hyperthermia and magnetic resonance imaging due to their special magnetic properties and fluidity. Particle size and magnetic properties of ferrofluids have an important role in these applications. In this work, magnetite-based ferrofluids have been synthesized via coprecipitation and hydrothermal methods. In the coprecipitation process, cysteine and dextran surfactants have been used as ferrofluid stabilizer and effect of synthesize temperature, time, pH and surfactant concentration have been investigated on... 

Nanoparticles have attracted the attention of many researchers because of the distinct physical and chemical properties. Besides the traditional applications in plastic reinforcement, fluid rheological additive, etc., the nanoparticles could be applied to many new fields and high-functional devices. Various chemical methods have been employed for the production of nanoparticles with narrow size distribution, such as co-precipitation, micro-emulsion, electrochemical synthesis, hydrothermal synthesis, sol–gel processing, flame spray pyrolysis, plasma chemical vapor deposition (CVD), hot-soap method and electrospray pyrolysis. But most of them have some problems so that only a few of them... 

In this research, a powder containing magnesium-aluminate spinel particles is prepared based on co-precipitation method and 5% , 10%, 15% and 20% zirconia-contained composites are produced as second phase from the synthesized powder. The raw materials used in the synthesis comprise hexa-hydrated magnesium nitrate, nona-hydrated aluminum nitrate, ammonium bicarbonate, 28% ammonium solution and distilled water. The properties of the powder is then investigated using STA, XRD and SEM tests. Also, XRD and SEM analyses as well as triple point flexural strength and Vickers hardness tests are carried out in order to investigate the effect of adding zirconia to the powders. The variations of the... 

In this study, the micro and nano particles of substituted strontium hexaferrites with nominal composition of SrFe12-xTix/2Znx/2O19 (x=0, 0.5, 1, 1.5, 2 and 2.5) were prepared by a co-precipitaion method. Ferrite-PVA composites (70:30) with thickness of 1.8mm were prepared at 220°C and 50Mpa. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) were employed for characterization of synthesized powders and composites. XRD and FTIR results showed that single phase hexaferrite were obtained for almost all of the... 

As contrast enhancement agent, two different structures of superparamagnetic nanoparticles were synthesized. Iron oxide nanoparticles were prepared through an alkaline coprecipitation method of Iron (II) and (III) ions. PEG-6000 was used as biocapping material and its effect on particle size, colloidal stability and cytotoxicity was evaluated. On the other hand, novel core/shell structures were produced by NaBH4 reduction process of iron (III) in an aqueous media following by further oxidation by two different methods using (CH3)3NO oxygen transferring agent and exposure to oxygen flow. In both cases, structural examinations were conducted via X-ray diffraction, electron microscopy and... 

The water-gas shift reaction, as a vital reaction in industry especially as a source of hydrogen for the manufacture of ammonia, is influential for all of the scientists and researchers in chemical engineering all around the world. In this research, high temperature water-gas shift (HTS) catalysts were investigated in order to study synthesis parameters and improvement of their performance and catalytic activity. The two catalyst categories; non pre-active and pre-active (magnetite-based samples, not requiring a reduction step prior to use) were prepared by co-precipitation method, using chloride, sulfate and nitrate metal (Fe, Cr, Cu) precursors and NaOH as precipitating agent (the aging... 

To study the kinetics of the yttria-stabilized zirconia produced by co-precipitation method from the chemical engineering point of view, this process was studied in two parts of hydrolysis and precipitation. the hydrolysis reaction was studied by titration method, and the rate constant and fraction of formation of hydrous zirconia was determined by applying Avrami equation. The results showed that the percentage of zirconia formation until the boiling time of 12 hours was zero and after 48 hours boiling was 2.81%. moment definitions were used In order to study the kinetics of precipitation. changes in precipitated powder concentration with pH of the solution was obtained based on the... 

In this study, a polyoxotungestate containing copper was impregnated as catalyst on a magnetic metal-organic framework (Fe3O4/MIL-101(Cr)). Initially, the desired polyoxotungestate was synthesized using sodium tungestate and sodium metasilicate salts and then copper(ІІ) ion was fixed on it. Subsequently, the MIL-101(Cr) metal-organic framework was prepared by solvothermal method; using chromium nitrate salt and 1,4-benzen dicarboxylic acid at 220 ◦C and was magnetized by co-precipitation method. Finally, the corresponding polyoxotungestate was stirred at ambient temperature for 24 h with MIL-101(Cr) and then the brown precipitate was separated using a magnet. Different techniques such as IR,... 

Reaction parameters in precipitation processes have a significant impact on the product characteristics. The process of formation of yttrium-stabilized zirconia precipitates was studied by co-precipitation method to investigate the parameters affecting particle size distribution. These studies aimed to investigate the reaction parameters and determine their effect on the size of the particles, taking into account the effects caused by the interaction of the parameters. To achieve this goal, the design of the experiment based on response surface methodology was used and five parameters of zirconyl chloride concentration, molar percentage of yttrium oxide, reaction time, mass percentage of... 

Electric vehicles and electronics such as laptops and smartphones require an efficient amount of energy conversion and storage. As one of the reliable systems in this field, lithium-ion batteries have high energy density and lower emissions. Cathodic material is a bottleneck in the development of lithium-ion systems due to its high cost and limited energy capacity. In this study, lithium-rich oxide cathode was synthesized in the liquid phase using the co-precipitation synthesis method using six-aqueous nickel nitrate and four-aqueous manganese chloride precursors. The material was analyzed by structural characterization analysis as well as electrochemical characterizations. In this project,... 

In the first section, due to the important role of nanocatalysts in different fields of chemistry, magnetic metal ferrite nanoparticles were synthesized. Ferrite nanoparticles were synthesized using co-precipitation method and were characterized. Then, these nanoparticles were applied as catalyst system for one-pot β-ketophosphonates and thiophosphate synthesis.This is a green and efficient route for S-P and C-P bond construction using copper ferrite nanoparticles as catalyst. The application of a highly active recyclable heterogeneous nanocopper ferrite catalyst for the oxyphosphorylation reaction of various alkenes was conducted under ligand-free conditions, in acetonitrile as solvent at... 

Magnetic nanoparticles, especially magnetic nanoparticles with silicate coatings, have attracted the attention of many researchers; Mainly because the silica shell can be functionalized with different molecules and functional groups and used in biological applications as targeted drug carriers. This study aimed to synthesize Fe3O4 core-shell nanoparticles with continuous and porous SiO2 shells on the surface of Fe3O4 particles. So that the coating is done evenly and with a strong connection. The procedure was as follows: core nanoparticle individual nanoparticles were made by the single-step method. To extract silica from rice husk, rice husk was subjected to heat treatment to obtain rice... 

In the present study, the process of recycling spent lithium batteries by co-precipitation method has been investigated. The process of regeneration of lithium batteries by co-deposition method consists of four stages. In the first stage, the cathodic material is separated from the aluminum foil using NMP solution, and then the cathodic material is heat treated at a temperature of 700 degrees. In the second stage, using sulfuric acid and hydrogen peroxide, the cathode material is leached at 60 ° C, pulp density 55 g / l, time 100 minutes, sulfuric acid concentration 3.25 M and volume percentage of hydrogen peroxide. 10% More than 99% of lithium, nickel, cobalt and manganese are leached. In...