Search results for " Nanoparticle"
showing 10 items of 936 documents
Optical properties of biocompatible polyaniline nano-composites
2006
Abstract Polyaniline (PANI) is an electro-active polymer of great interest thanks to its outstanding physical and chemical properties which make it suitable for various applications in optics, bioelectronics, biosensors, diagnostics and therapeutic devices. Unfortunately, PANI is infusible and insoluble in most common solvents and, thus, very difficult to process. In the attempt of improving processability, yet preserving its interesting properties, PANI has been synthesized in the form of particles and dispersed into a hydrogel matrix. The synthesis of PANI–hydrogel composites proceeds via γ-irradiation of PANI dispersions as obtained by ‘in situ’ polymerization of aniline in the presence …
Environment assisted photoconversion of luminescent surface defects in SiO 2 nanoparticles
2017
Abstract Time-resolved photoluminescence investigation on SiO 2 nanoparticles was carried out in controlled atmosphere, with the aim to discern the effects induced on the typical blue luminescence band by high power UV Nd:YAG laser photons (4.66 eV) and by some selected molecular species of the air (O 2 , N 2 , CO 2 , H 2 O). These factors ultimately determine both the brightness and photostability of the emitting defect, so as to limit the unique and attracting potentialities offered by this system in many applicative fields. Here it is highlighted that the effects due to photons and molecules, singularly considered, are not additive, the radiation being more dramatic in reducing the emiss…
New transport properties of ferrocolloids: magnetic Soret effect and thermomagnetoosmosis
2005
The paper deals with critical analysis of experiments on thermodiffusion in ferrocolloids. The observed magnetic Soret effect is significantly stronger than that predicted theoretically. It is shown that the main reason for that is the influence of a magnetic field on mass diffusion. Besides, some measurements are effected by uncontrolled thermal and solutal magnetic convection. Even in porous media, when macroscopic convection is depressed, thermodiffusion can be disturbed by microconvective mass transfer induced by particle magnetophoresis on filter grains.
Thermally Induced Structural Modification of Silica Nanoparticles Investigated by Raman and Infrared Absorption Spectroscopies
2010
We report an experimental investigation by Raman and infrared (IR) absorption spectroscopies on the structural modifications induced by isochronal thermal treatments on amorphous SiO2 nanoparticles (fumed silica). In particular, three different commercial types of this material, characterized by particle mean diameters of 7, 14, and 40 nm, were subjected to thermal treatments from 100 up to 1000 °C. We found that some properties of fumed silica, such as the SiOSi mean bond angle, ring size distribution, and surface adsorbed water content, are drastically different from those of common bulk silica materials and intimately related to the particles' dimension. The SiOSi mean bond angle, probed…
FERULIC ACID INHIBITS OXIDATE STRESS AND CELL DEATH INDUCED BY Ab OLIGOMERS: IMPROVED DELIVERY BY SOLID LIPID NANOPARTICLES.
2009
Oxidative stress and dysfunctional mitochondria are among the earliest events in AD, triggering neurodegeneration. The use of natural antioxidants could be a neuroprotective strategy for blocking cell death. Here, the antioxidant action of ferulic acid (FA) on different paths leading to degeneration of recombinant beta-amyloid peptide (rAbeta42) treated cells was investigated. Further, to improve its delivery, a novel drug delivery system (DDS) was used. Solid lipid nanoparticles (SLNs), empty or containing ferulic acid (FA-SNL), were developed as DDS. The resulting particles had small colloidal size and highly negative surface charge in water. Using neuroblastoma cells and rAbeta42 oligome…
Synchronization of coupled single-electron circuits based on nanoparticles and tunneling junctions
2009
We explore theoretically the synchronization properties of a device composed of coupled single-electron circuits whose building blocks are nanoparticles interconnected with tunneling junctions. Elementary nanoscillators can be achieved by a single-electron tunneling cell where the relaxation oscillation is induced by the tunneling. We develop a model to describe the synchronization of the nanoscillators and present sample calculations to demonstrate that the idea is feasible and could readily find applications. Instead of considering a particular system, we analyze the general properties of the device making use of an ideal model that emphasizes the essential characteristics of the concept.…
Deposition of Cu Nanoparticles on the Surface of Metallic Aluminum
2012
Deposition of Cu particles by electrolysis at constant electrode potential and by internal electrolysis methods was investigated. The composition of deposited material was confirmed by optical and scanning electron microscope methods. Combination of electrolysis at constant electrode potential with internal electrolysis method was found most effective for fabrication of nanoparticle arrays. Single crystalline Cu particles are fabricated by internal electrolysis, while polycrystalline ones obtained by combined chronopotentiometric and internal electrolysis methods. The formation mechanism of Cu nanoparticles is described.
[Ag67(SPhMe2)32(PPh3)8]3+: Synthesis, Total Structure, and Optical Properties of a Large Box-Shaped Silver Nanocluster
2016
Engineering the surface ligands of metal nanoparticles is critical in designing unique arrangements of metal atoms. Here, we report the synthesis and total structure determination of a large box-shaped Ag67 nanocluster (NC) protected by a mixed shell of thiolate (2,4-dimethylbenzenethiolate, SPhMe2) and phosphine (triphenylphosphine, PPh3) ligands. Single crystal X-ray diffraction (SCXRD) and electrospray ionization mass spectrometry (ESI-MS) revealed the cluster formula to be [Ag67(SPhMe2)32(PPh3)8]3+. The crystal structure shows an Ag23 metal core covered by a layer of Ag44S32P8 arranged in the shape of a box. The Ag23 core was formed through an unprecedented centered cuboctahedron, i.e.,…
Insights into the Mechanism of Cumene Peroxidation Using Supported Gold and Silver Nanoparticles
2013
Due to the considerable industrial implications, an in-depth study of cumene peroxidation using supported gold and silver nanoparticles was carried out to gain more insight into the mechanism of this reaction. Supported gold nanoparticles were found to efficiently catalyze the decomposition of cumene hydroperoxide with a selectivity of 25% at 80 °C when using gold supported on hydrotalcite (AuNP@HT), and 2-phenyl-2-propanol (i.e., cumyl alcohol) was the main product. Further, silver nanoparticles supported on hydrotalcite (AgNP@HT) converted cumene to cumene hydroperoxide at 80 °C with 80% selectivity. Both benchtop and oxygen-uptake experiments were used to probe the reaction mechanism and…
Catalytic properties of Ag-PolyaminoβCD NPs for reduction of nitroarenes
2014
The reduction of nitroarenes is a key reaction involved in the synthesis of several compounds such as drugs, pesticides or dyes. During the last years Pd and Ag NPs have been used as catalysts to carry out this reaction with NaBH4. However several mechanistic aspects of the process are still unclear; in particular there is not agreement about the kinetic order of these reactions, whether 0-th or 1-st order in the substrate[1]. The aim of this work is to use a novel catalytic systems constituted by Ag-NPs coated with different polyamino-βCDs (Figure 1)[2], to carry out the reduction of some aromatic nitrocompounds using NaBH4 as the reducing agent, and to determine the kinetic features of th…