Papers by Keyword: Nanoparticle

Abstract: Mg-Co nano crystalline ferrites having general formula Mg1-xCoxFe2O4 (x=0, 0.05, 0.1, 0.15, 0.2, 0.25) were prepared by co-precipitation method. X-ray powder diffraction (XRD) patterns of the prepared samples show the formation single spinel phase. The crystallite size, lattice parameters and porosity of samples were calculated by XRD data analysis as function of cobalt concentration. The crystallite size for each sample was calculated using the Scherrer formula considering the most intense (3 1 1) peak lies in the range 27-35 nm. The lattice parameters increased with increase of cobalt concentration. It is because of the fact that cobalt has greater ionic radius then magnesium. The dielectric constant, dielectric loss tangent and ac electrical conductivity of the prepared samples is also measure. The observed variation in electrical and dielectric properties is explained on the basis of cations distribution among tetrahedral (A) and octahedral (B) sites. The variance in saturation magnetization, remanence magnetization and magnetic moment was also measured from BH curve of samples.

Abstract: Objective: To prepare water-soluble chitosan(WSC) nanoparticles(WSC-NPs) and microspheres(WSC-MPs) , exam the morphology and particle sizes of them and study their effect on lowering lipids . Methods: WSC-NPs and WSC-MPs were prepared by ionic gelation process and spray-drying methods respectively. The effect of WSC-NPs and WSC-MPs on lowering lipids was evaluated by measuring its binding capacities of lipids in the conditions simulating human gastrointestinal tract in vitro. Also, the morphology and particle sizes of WSC-NPs and WSC-MPs were examined under scanning electron microscopy (SEM) and particle sizer. Resluts: WSC-NPs and WSC-MPs were nearly spherical in shape and the mean particles size varied from 200-400 nm and 3-7 μm respectively; The lipids-binding capacities of WSC-NPs and WSC-MPs were more effective compared with water-soluble chiosan. The lipids-binding capacity were enhenced when the particle size were decreased. Conclusion: WSC-NPs and WSC-MPs will be better fat-lowing food additives to replace water-soluble chitosan.

Abstract: We have investigated the absorption of 0.9, 1.4 nm silicon carbide nanoparticles (SiC NPs) by time-dependent density functional calculations, focusing on the effect of different oxygen adsorbates of the surface. We have found that negatively charged Si-O−, Si-COO− defects dramatically lower the optical gap of SiC NPs. Our findings can help interpret recent controversary experiments on colloidal SiC NPs.

Abstract: The crystallization properties of magnetic nickel ferrite (NiFe₂O₄) nanoparticles have been investigated from the comparison of the characteristics of NiFe₂O₄ nanoparticles prepared by using the solvent co-precipitation method at different temperatures. The results indicated that the magnetic particles were in the spinel phase and the crystallite size changed increasingly with the calcined temperatures, demonstrating the high saturation magnetization moment, as close to the well-crystallized NiFe₂O₄ particle, and suitable soft magnetic properties.

Abstract: TiO₂ nanoparticles (anatase) with diameters between 2 and 4 nm were synthesized by controlled hydrolysis of a solution of titanium(IV)isopropoxide to which ⁴⁴Ti in 4M HCl was added. Inactive nanoparticles were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM), the active ones were analyzed by measuring the nuclear quadrupole interaction (NQI) of the I = 1 state in ⁴⁴Sc using time differential perturbed angular correlation (TDPAC). Rather broad distributions were obtained. We also synthesized nanowires with typical diameters of 2 nm and 100 nm length using shape controllers. They were analyzed by HRTEM and XRD. The material turned out to be TiO₂(B). The ⁴⁴Ti was added by impregnation and diffusion at 180°C for two hours. Two well-defined NQI signals were observed which we tentatively assigned to the volume fraction and the “surface” fraction, i.e. Ti probes with OH-termination. In addition, we studied AMT-100 (anatase, uncoated, 6 nm) from Tayca, Eusolex T-2000 (rutile, Al2O3-coated, 20×20×100 nm³, simethicone additive) and P25 (mainly anatase, uncoated, 20 nm diameter) using the impregnation and diffusion method. P25 and the isolated rutile fraction from P25 yield spectra which correspond to anatase and rutile volume signals plus their surface signals, respectively. TDPAC thus proved very useful in characterizing the nanomaterials, especially their disorder, by measuring the NQI. In addition, information on surface properties is obtained. The relatively narrow surface signals indicate a lower degree of disorder and are possibly also a result of partial motional averaging of Ti-signals with OH-bonds due to mobile H-atoms.

Abstract: A long pulsed laser ablation with a moving target at high speed technique was applied to prepare tellurium nanoparticles from a tellurium target under argon gas at atmospheric pressure. The prepared nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), and X-ray diffraction (XRD). The influence of the moving speed of the target on the size, morphology and crystallographic structure of the nanoparticles was investigeated. The results show that for the target moving at high speed without burning of the target the production of isolated nanoparticles is obtained. The diameter of the nanoparticles is ranging from 30 to 200 nm.

Abstract: This study reports on the controlled single conductive path in ReRAM formed by embedding Pt nanoparticles (Pt NPs) in NiO film. Homogenous Pt NPs produced and placed by ferritin protein produce electric field convergence which leads to the controlled conductive path formation. The ReRAM with Pt NPs shows stable switching behavior. A Pt NP density decrease results in an increase of OFF state resistance and decrease of forming voltage, whereas ON resistance was independent from the Pt NP density, which indicates that a single metal NP in a memory cell will achieve extremely high-on/off resistance ratio, low power operation and stable operation.

Abstract: In this Study, the Tripolyphosphate-Chitosan (TPP-CS) Nano-Carrier was Prepared by Polyelectrolyte Complexation. TPP and CKGM are Polyanion, and can Interact with Cationic Chitosan by Electrostatic Forces. the Nanoparticles Size was Analyzed by the Transmission Electron Micrographs (TEM) and Scattering Electron Micrographs (SEM). FTIR Confirmed Tripolyphosphoric Groups of TPP and CKGM Linked with Ammonium Groups of Chitosan in the Nanoparticles. the CS Nps were Loaded with the Anticancer Drug, Berberine, by Different Concentration of Cross-Linking Agent. the Zeta Potentials of CKGM and CS were Shown as a Function of Ph. it was Observed that CS has Strong Interaction with CKGM about Ph 5.5. the CKGM-CS Nanoparticles were Formed by Mixed Different Weight Ratio of CS and CKGM. the Morphology of CKGM-CS was Characterized by FESEM. the Size of CKGM-CS Particles was Smaller than 150 Nm. the Zeta Potential of CKGM-CS Particles was Proved that the Polymer Ratio can Control the Charge Density.

Abstract: Drug delivery systems with active targeting ligand provide improved therapeutic efficiency due to the selectivity towards tumor cells. In this paper we prepared drug loaded nanoparticles (NPs) using folate (FA) incorporated chitosan (FA-CS) based on ionic gelation technology. FA-CS NPs were spherical in shape with an average particle size of 100 nm, while 5-fluorouracil (5-FU) loaded NPs became less circular with average particle size of 100-500 nm. NPs made from FA-CS conjugates exhibited improved capability to encapsulate hydrophilic 5-FU. It was found 5-FU distributed in FA-CS NPs in solid solution state. In vitro release results demonstrated the release of 5-FU from FA-CS NPs was more controllable as compared to that of CS NPs.

Abstract: In this paper, a novel biodegradable and fluorescent polymer: fluorescein-polylactide (FL-PLA) was synthesized by FL and lactide in the method of ring-opening polymerization with the catalysis of Sn(Oct)₂ under 130°C . The structure and molecular weight of FL-PLA were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (¹H-NMR) spectroscopy, and gel permeation chromatography (GPC). The molecular weight of FL-PLA increased from 9.03×10³ to 21.24×10³ with decreasing the amount of FL and kept a narrow distribution. The result of differential scanning calorimeter (DSC) showed that T_g increased from 52 to 72°C with increasing the molecular weight of polymer. Moreover, the average number content of FL in each molecular chain decreased from 0.96 to 0.81 with decrement of the amount of FL. Furthermore, FL-PLA showed the fluorescence property, and the fluorescence intensity could be controlled by the amount of FL. The FL-PLA nanoparticles were prepared by mixing the good and poor solvent, and the diameter was about 3 μm with regular spherical morphology.