International Journal of Nanoparticles (7 papers in press)
Structural and Magnetic properties investigation of sintered MnxMg1-xFe2O4 ferrites from nanopowders prepared via co-precipitation method
by Sohrab Manouchehri, Seyed Taghi Mohammadi Benehi, Mohammad Hassan Yousefi, Javad Zahmatkesh, Mohsen Abdollahi
Abstract: Nanoferrite powders having composition MnxMg1-xFe2O4 (x= 0.0, 0.2, 0.4, 0.6, 0.8) were synthesized by the chemical co-precipitation method and then sintered as the pellets. The X-ray diffraction (XRD), Alternating Gradient Force Magnetometer (AGFM) techniques and Curie temperature measurement were used to carry out this study. The XRD patterns confirm the nanosized dimension of the samples and showed that the samples are single phase cubic spinel nanoferrites. From the analysis of XRD data using Scherrers formula, the average crystallite size (DXRD) of the particles was found to decrease from 81 to 55 nm with increasing manganese substitution. Substitution of Mn2+ in MgFe2O4 causes an increase in the lattice constant (a) from 8.35 to 8.43
Keywords: Nanoferrite powders; Co-precipitation method; Sintering; Spinels; Magnetic properties
Synthesis and Microstructure of Gallium Substituted Cobalt Ferrite Nanoparticles by Hydrothermal Method
by Gayathri Sivaraman, Kalainathan sivaperuman
Abstract: Magnetic CoFe2-xGaxO4 nanoparticles were successfully synthesized via hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM).The experimental results showed that the CoFe2-xGaxO4 were composed of single phase spinel structure and the average crystallite size is between 42 and 57nm.The saturation magnetization (Ms) of the CoFe2-xGaxO4 nanoparticles decreased linearly as the contents of Ga increased for x = 0.2 -0.8 which can be used in sensor applications.
Keywords: Magnetic Nanoparticles;Hydrothermal method;FESEM;HRTEM;VSM magnetic studies.
Silver nanoparticles bioreduction by Dittrichia Viscosa leaves extract and its bactericidal effects
by sofiane sedira, Nadjeh Sobti
Abstract: A variety of chemical and physical procedures could be used for synthesis of silver nanoparticles. However, these methods are confronted with many problems including use of toxic solvents. A green method for silver nanoparticles synthesis using Dittrichia Viscosa leaves extract is proposed. This plant is available in abundance on the coastal Mediterranean countries can replace polyvinylpyrrolidone conventionally used in the synthesis of silver nanoparticles. Polyol method (reflux heating) was used for silver nanoparticles synthesis. The nanoparticles obtained were characterized using x-ray diffraction, ultravioletvisible spectroscopy, Raman spectroscopy, Fourier Transform Infrared spectroscopy and transmission electron microscopy. Compared with silver nanoparticles prepared by polyvinylpyrrolidone and ethanol 96%, the bactericidal effect of silver nanoparticles synthesized by Dittrichia Viscosa is more efficient against bacteria. No toxic solvents were used in the present work; therefore, it is an environmentally safe method with potential for biomedical applications.
Keywords: silver nanoparticles, Dittrichia Viscosa, bactericidal effect.
Preparation of Nanospheres from Oxidized Cellulose nanofibrils via Poylelectrolite complexation
by Rajasekar Sankar
Abstract: Cellulose is one of the most abundant natural polymer, that consist of both crystalline phase and amorphous region. When disturb the amorphous regions of the cellulose fibers by mechanical degradation that weaker amorphous regions cuts down into crystalline regions that crystalline regions are consist of nanometer size in nature. The TEMPO specific oxidation of cellulose fiber is only the method providing carboxylated cellulose nano-crystals without formation of aldehydic content. The surface carboxylated cellulose was prepared by TEMPO-mediated specific oxidation method. Supernatant of the reaction mass contains entirely oxidized cellulose nanofibrils (Polyglucuronans) that was isolated by precipitation with methanol. The anionic character of the cellulose nanocrystals were enabling to undergo polyelectrolyte complexation with cationic polymers. Prepared nano-spheres with oxidized cellulose through polyelectrolyte complexation with chitosan. Based on this method nano-sphere were prepared with chitosan in aqueous medium in different concentrations. Shape of the nano-sphere was identified by using SEM. When increase the concentration of chitosan, the nano-spheres were stick on excess chitosan film. To overcome the spheres agglomeration, the surface of that sphere was hydrophobically modified with alkyl tail (Decyltrimethylammonium bromide). The hydrophobic modification was given individual nano-spheres and they were distinctly identified by SEM. It is hoped that the finding in this communication will help in deriving a new nanomaterial of CNF, which will act as a nano carrier for delivery applications.
Keywords: Nanomaterials, Oxidized cellulose nanofibrils, Nanospheres polyelectrolyte complexation.
Genotoxicity detection following exposure to silver nanoparticles in African catfish (Clarias gariepinus)
by Alaa El-Din Sayed
Abstract: The aim of the present study is to evaluate the cytotoxic and genotoxic effects of silver nanoparticles (Ag-NPs) towards African catfish (Clarias gariepinus). Adult male catfish was exposed to 0, 25, 50, and 75 mgl-1 Ag-NPs for two weeks. Exposure to Ag-NPs exerted an increase in mortality rate and behavioral changes compared to control. A fluorescent microscopy examination was used to assess the cytotoxic effect. There was a fifteen-fold greater extent of apoptosis in erythrocytes of exposed fish to 75 mgl-1 compared to control fish. No significant differences in the extent of apoptosis were detected in 25 mgl-1 and 50 mgl-1 exposed fish. Also, The genotoxic effect of the tested compound was evaluated via micronucleus and DNA fragmentation assays. The micronucleated erythrocytes were observed as well as, DNA damage was recorded in the liver, kidney, gill, and muscles in all exposed groups and percentage elevated with the increase of Ag-NPs concentration. Overall, our results indicate that, Ag-NPs exhibited the both genotoxic and cytotoxic effects in African catfish.
Keywords: Ag-NPs; Apoptosis, Micronuclus; DNA; Clarias gariepinus
Biosynthesis of Silver Nanoparticles Using Unriped Carica Papaya Fruit Extract with Different PH Conditions
by Hooi Chien Ng, Cheng Seong Khe, Azizan Aziz, Zulkifli Merican Aljunid Merican, Rajalingam Sokkalingam, Thiam Leng Chew, Chin Wei Lai
Abstract: Silver nanoparticles were successfully synthesized at room temperature from silver nitrate using unripe Carica papaya fruit extract as a reducing and capping agent. pH of the reaction solution was adjusted with the addition of sodium hydroxide from pH 5.6 (original pH of the broth) to pH 6.5, pH 7.5 and pH 8.5. Quasi spherical silver nanoparticles were obtained across the studied pH range. The average particle size obtained decreased from 34 nm to 15 nm as the pH of the solution increased from 5.6 to 8.5. From the observations and ultra violetvisible spectrophotometer analysis, the rate of reduction and formation of silver nanoparticles increased as the pH increased. The crystalline nature of the as-synthesized silver nanoparticles in a cubic structure was confirmed by the peaks in X-ray diffraction and selected area electron diffraction. From Fourier transform infrared spectra, it was found that proteins in unripe papaya fruit extract were strongly bounded to the surface of silver nanoparticles as a capping agent. The thin layer of protein coating also further confirmed under high resolution transmission electron microscope. A plausible formation mechanism has been briefly proposed.
Keywords: Biosynthesis; silver nanoparticles; Carica papaya fruit extract; pH; twinning
Special Issue on: CIMDD 2013 Behaviour of Materials
Electrical properties of Nanoscale Field Effect Transistor
by Sana Kausar, Shirish Joshi
Abstract: In this paper structure of a H-passivated silicon nanowire along direction with hexagonal cross section is defined by using Virtual nanolab(VNL), and set up a nanoscale field effect transistor (FET) structure with a wrap-around gate. Then the transmission spectrum and conductance is computed as the gate bias is varied. The device characteristic curve and conductance with respect to gate voltage is studied. Also effect of doping of Al atom on characteristic curve and conductance of nanoscale field effect transistor is analyzed.
Keywords: DFT, GGA, nanowire