The stability of green nanoparticles in increased pH and salinity for applications in oil spill-treatment

AbstractThe melting of the permanent ice cover in the arctic region due to the climate change is increasing industrial activity in the region and also consequently there is the enhanced risk for oil-spills. Therefore, there is a need for the development of green chemicals for oil-spill treatment in the arctic region. Carboxymethylated chitosan nanoparticles were cross-linked with Mg, Ca or Sr and the stability of nanoparticles in increased pH and salinity was studied. The carboxymethylation of chitosan was investigated with FTIR and the nanoparticles were studied with dynamic light scattering and SEM. The nanoparticles cross-linked with Ca ions were found to be most stable in increased salinity and pH. The interaction of Ca cross-linked nanoparticles with dodecane in water was also demonstrated. The nanoparticles showed promising potential for applications in oil-spill treatment

Stock Market Volatility, Speculative Short Sellers and Weekend Effect: International Evidence

We test the Chen and Singal (2003) hypothesis that speculative short sellers add to the selling pressure on Mondays, and hence add to the weekend effect, by examining evidence from 60 market indices. We find strong evidence that, until about a decade ago, the actions of short sellers could explain the weekend ef- fect. Recently, however, the relationship between short sales and the weekend effect is gradually dissi- pating in developed markets, probably due to the cross-market hedges of short sellers. These findings strongly support, rather than weaken, the Chen and Singal hypothesis

Synthesis and magnetic properties of CoPt–poly(methylmethacrylate) nanostructured composite material

We have prepared nanometer-sized CoPt particles dispersed in a poly~methyl methacrylate~PMMA!matrix, as a novel nanostructured magnetic plastic, through a soft chemical processing route. In this work, CoPt nanoparticles were successfully synthesized from a solution phase reduction system in the presence of capping ligands and stabilizing agents at high temperature. The CoPt nanoparticles were annealed at 400 °C for 3 h, and were subsequently re-dispersed inmethylmethacrylate~monomer! . The polymerization was induced by a UV source and the hardness of final product was adjusted by varying the amount of monomeric cross-link agent. Annealed bare CoPt nanoparticles as a ‘‘core’’ material and CoPt–PMMA composite material were characterized by using energy dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction, indicating that we are able to prepare CoPt nanoparticles with 10 nm in diameter ~after annealing by employing this high temperature colloidal processing method. Magnetic investigation of this CoPt–PMMA material indicates an intrinsic coercivity of 300 Oe at 300 K and 1665 Oe at 5 K

A Simple Extrusion Method for the Synthesis of Aligned Silica Nanowires Using the Template of a Rigid Surface Mesophase

Long range alignment of silica nanowires has been accomplished by extrusion of a novel surfactant mesophase prior to silica synthesis

Stock Market Volatility, Speculative Short Sellers and Weekend Effect: International Evidence

We test the Chen and Singal (2003) hypothesis that speculative short sellers add to the selling pressure on Mondays, and hence add to the weekend effect, by examining evidence from 60 market indices. We find strong evidence that, until about a decade ago, the actions of short sellers could explain the weekend ef- fect. Recently, however, the relationship between short sales and the weekend effect is gradually dissi- pating in developed markets, probably due to the cross-market hedges of short sellers. These findings strongly support, rather than weaken, the Chen and Singal hypothesis

Synthesis and magnetic properties of CoPt–poly(methylmethacrylate) nanostructured composite material

We have prepared nanometer-sized CoPt particles dispersed in a poly~methyl methacrylate~PMMA!matrix, as a novel nanostructured magnetic plastic, through a soft chemical processing route. In this work, CoPt nanoparticles were successfully synthesized from a solution phase reduction system in the presence of capping ligands and stabilizing agents at high temperature. The CoPt nanoparticles were annealed at 400 °C for 3 h, and were subsequently re-dispersed inmethylmethacrylate~monomer! . The polymerization was induced by a UV source and the hardness of final product was adjusted by varying the amount of monomeric cross-link agent. Annealed bare CoPt nanoparticles as a ‘‘core’’ material and CoPt–PMMA composite material were characterized by using energy dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction, indicating that we are able to prepare CoPt nanoparticles with 10 nm in diameter ~after annealing by employing this high temperature colloidal processing method. Magnetic investigation of this CoPt–PMMA material indicates an intrinsic coercivity of 300 Oe at 300 K and 1665 Oe at 5 K

Self-assembly of FePt nanoparticles into nanorings

The application of nanoparticles as quantum dots in nanoelectronics demands their arrangement in ordered arrays. Shape controlled self-assembly is a challenge due to the difficulties of obtaining proper self-assembling parameters, such as solvent concentration, organic ligands, and nanoparticle size. In this article, hard magnetic FePt nanoparticles were synthesized using a combination approach of reduction and thermal decomposition. The nanoparticles are about 4.5 nm and appeared as truncated octahedral enclosed by the {100} and {111} crystal facets of fcc structure. The nanoparticles are of hexagonal close packing and orient randomly in the self-assembly nanoarrays. By diluting the solution for large-area self-assembly, monolayer, submonolayer, and multilayer nanorings of FePt nanoparticles were formed. The nanoring formation is determined by hydrodynamics, surface effects, and interaction between the FePt nanoparticles and substrates

Photoinduced electrooptics in the In2O3 nanocrystals incorporated into PMMA matrixes

We have observed an appearance of clear morphological structure in composites containing In2O3 nanocrystals (NCs) incorporated into polymethyl methacrylite (PMMA) matrices under optical treatment by a polarized femtosecond laser. The initial photoinduced treatment was carried out using a Ti:sapphire femtosecond laser emitting 140 fs p-polarized light at a maximum spectral wavelength 775 nm with pulse repetition 1 kHz. It was found that the average morphological radius is varied maximally only during illumination at liquid helium temperature (T = 4.2 K). The morphological average mean radius is strictly dependent on the sizes of incorporated In2O3 NCs. Afterwards we measured the linear electrooptic effect at cw He–Ne laser wavelength 633 nm during simultaneous treatment by 1060 and 530 nm coherent beams of a Nd–YAG picosecond laser. We have established that a decrease of the average morphological mean radius favours an increase of the optically poled linear electrooptic coefficient. The diameters of In2O3 NCs were evaluated using transmission electron microscopy (TEM) and light-scattering techniques, whereas the NC sizes and morphological average mean radius of formed nanocomposites were estimated by atomic force microscopy (AFM). A relationship between the diameter of the NC, composite morphological mean average radius and effective linear electrooptic coefficient was established.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58122/2/cm7_1_016204.pd