nanoparticle Articles
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Effect of surface modification of SiO 2 nanoparticles on the mechanical properties of ambient pressure dried silica aerogels
In this study, we synthesised silica aerogel composites using SiO 2 nanoparticles and studied the effects of surface modification of silica nanoparticles on the properties of silica aerogel composites. The surface condition of the silica nanoparticles was controlled to be either hydrophobic or hydrophilic. Accordingly, the effect of the surface chemical state of silica nanoparticles on the ...
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Molecular dynamics simulations of nanoparticles
Nanoparticles are becoming increasingly important in many areas of nanotechnology. Here we use classical molecular dynamics simulations to investigate the competition between surface and volumetric effects in metal nanoparticles. In particular, we review work on the melting of isolated nanoparticles, solid-solid transitions in nanoparticles and the deposition of nanoparticles on substrates. In ...
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Design of bimetallic nanoparticles
A novel preparation method to control a microstructure and the resulting structure and activity relationship are presented to aim a rational design of the well defined bimetallic nanoparticles. Nanoparticles are engineered inside the supercage of faujasite type zeolite. The reduction mechanism for the bimetallic nanoparticles is proposed based on the results of X-ray absorption fine structure, ...
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Nucleation phenomenon in nanoparticle self-assemblies
Dispersed nanoparticles self-assemble into complex structures when segregated from the solvent either by evaporation or precipitation. Thus, different micro- and macroscopic structures (opals, fractals, liquid crystals) formed by nanoparticles are observed as a result of the balance between electrostatic forces, surface tension, volume exclusion, substrate topography and affinity, and size, shape ...
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Commercial scale production of inorganic nanoparticles
This review focuses on the current trend in the commercial scale production methods of inorganic nanoparticles. The limiting factors for the scalability of synthesis methods are explained and the relationship between commercial nanoparticle materials and production methods is discussed. Particular emphasis is placed on the fact that different synthesis techniques lead to different properties of ...
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Dispersion and stability of titanium dioxide nanoparticles in aqueous suspension: effects of ultrasonication and concentration
The increasing applications of titanium dioxide (TiO2) nanoparticles raise concerns about their potential environmental impacts. To investigate the fate and transport of TiO2 nanoparticles in aqueous suspension, ultrasonication is widely used for the dispersion of TiO2 nanoparticles in laboratory-scale studies. There is a pressing need for detailed information on the dispersion and stability of ...
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Structural and chemical changes during the growth of Fe nanoparticles in SiO
2under low energy ion implantationLow energy (15 keV) Fe implantation into SiO2 (400 nm) on Si initially leads to the formation of very small Fe nanoparticles. The Fe nanoparticles grow in size and remain crystalline as the fluence is increased. At the same time there is Si and oxygen sputtering that reduces the thickness of the SiO2 layer. It is this sputtering that leads to Fe nanoparticles that protrude from the surface for ...
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Optimizing adsorption of Cr(VI) from aqueous solutions by NiO nanoparticles using Taguchi and response surface methods
In the present study, nickel oxide nanoparticles synthesized by the sol–gel method were used as an effective adsorbent for the removal of Cr(VI) from aqueous solutions. To do so, the effect of four parameters including the concentration of Cr(VI), the dosage of NiO, contact time, and pH on the removal of Cr(VI) by NiO nanoparticles were studied. In order to examine and describe the ...
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Dielectric, magnetic and optical properties of nanocomposites
Nanocomposites are media made of nanoparticles embedded in a matrix. Depending on the nanoparticle types and shapes, nanocomposites can have different properties. I discuss here dielectric and magnetic composites at low, as well as, high frequencies. At low frequencies, dielectric and magnetic properties can be enhanced by using elongated nanoparticles. At high frequencies various photonic, ...
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Metallic nanoparticles for application in electronic non-volatile memories
Nanoparticle memories have appeared during last years as a possible solution to overcome the scaling issue of electronic nonvolatile memories. Ultimately, we are looking for nanoparticle memories to significantly decrease the voltage needed to write/erase the memory without compromising its retention characteristics. As an alternative to semiconductor nanoparticles which have been intensively ...
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Spectroscopic investigation of II–VI core-shell nanoparticles: CdSe/CdS
CdSe and CdSe/CdS core/shell nanoparticles were prepared by a one-pot synthesis process. The CdSe/CdS core/shell nanoparticles showed red-shift absorption and emission spectra compared to the CdSe core. An optimal reaction time for CdS to form on the CdSe nanoparticles was evaluated and the highest photoluminescence yield of approximately equal to 20% was observed for the core/shell ...
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Synthesis of ZnO whiskers via EDTA–assisted hydrothermal routes
Uniform ZnO whiskers with a length of 3.5–4.0 μm and a diameter of 180 nm have been synthesised via the EDTA–assisted hydrothermal route, using ZnO nanoparticles as the raw material and NaOH solution as the reaction medium. In order to convert the ZnO nanoparticles to ZnO whiskers via the dissolution–hydrothermal precipitation route, ZnO nanoparticles were firstly dissolved ...
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Exchange bias in ferromagnetic nanoparticles embedded in an antiferromagnetic matrix
The fabrication process and magnetic properties of three types of system consisting of ferromagnetic (FM) particles embedded in an antiferromagnetic (AFM) matrix are discussed. The preparation techniques are ball milling, H2 partial reduction of oxides and nanoparticle gas condensation. The magnetic properties of the FM/AFM composites are shown to depend strongly on the morphology of the system ...
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Exergy analysis of hydrocarbons mixture refrigerants R436A and R436B as a drop in replacement for R134a with TiO
2nanoparticlesThe refrigerator exergy efficiency (EE) with nanoparticles in the working fluid was investigated experimentally. Mineral oil (MO) with TiO2 nanoparticles mixtures were used as the lubricant instead of Polyol ester (POE) oil in the R134a, R436A (R290/R600a–56/44–weight %) and R436B (R290/R600a–52/48–weight %) refrigerator. The results indicate that R134a, R436A and R436B and MO with TiO2 ...
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Stability of Fe-oxide nanoparticles coated with natural organic matter under relevant environmental conditions
Manufactured nanoparticles (MNPs) are increasingly released into the environment and thus research on their fate and behaviour in complex environmental samples is urgently needed. The fate of MNPs in the aquatic environment will mainly depend on the physico-chemical characteristics of the medium. The presence and concentration of natural organic matter (NOM) will play a significant role on the ...
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Magnetic spinel ferrite nanoparticles from microemulsions
Microemulsion methods have been used to prepare a wide range of spinel ferrite nanoparticles with low size distribution. Synthesis conditions are summarised for both normal micelle (o/w) and reverse micelle (w/o) synthesis procedures with examples over a variety of ferrite nanoparticles (MFe2O4; M = Co, Fe, Mg, Mn, Cr, Zn). Size selection through control over metal cation concentration and ...
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Synthesis and characterisation of gold nanoparticles using Mentha piperita leaf extract: a green, non-toxic and rapid method
Eco-friendly synthesis of gold nanoparticles (AuNPs) using Mentha piperita leaf extract was addressed in this work. Different extract concentrations (0.5, 1.0 and 1.5% w/v) were used for the synthesis of AuNPs. Reaction rate increased with temperature and leaf extract concentration; however, prolonged heating might affect negatively the AuNPs synthesis. AuNPs in colloid state were synthesised ...
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Characteristics of colloidal copper particles prepared by using polyvinyl pyrrolidone and polyethylene glycol in chemical reduction method
A simple chemical reduction method is used to prepare colloidal copper nanoparticles where polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) are used as stabiliser, size controller and capping agents. The main purpose of this paper is to report about the large improvement in replacing PEG by PVP in the reduction synthesis of copper nanoparticles. From the TEM results it was found that ...
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On inherent irreversibility in Sakiadis flow of nanofluids
The problem of entropy generation and inherent irreversibility in the steady boundary layer shear flow of nanofluids over a moving flat plate is studied numerically. The governing partial differential equations are transformed into ordinary differential equations using a similarity transformation and then solved numerically by a Runge–Kutta–Fehlberg method with the shooting technique. Two types ...
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EFSA Publishes Safety Assessment of Selenium Nanoparticles for use in Active Food Contact Materials
The European Food Safety Authority (EFSA) Panel on Food Contact Materials, Enzymes, Flavorings, and Processing Aids evaluated food contact material (FCM) Substance No. 1070, which incorporates selenium nanoparticles into the adhesive middle layer of multilayer laminates with an outside polyethylene terephthalate (PET) layer and an inner polyolefin (food contact) layer. The results of the ...
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