Current Issue : January - March Volume : 2014 Issue Number : 1 Articles : 7 Articles
Mesoporous silica nanoparticles (MSNs) were synthesized by sol-gel reaction at normal pressure by using TEOS as a silica source\r\nand CTAB as a directing agent in ammonia solution at 323K subsequently calcined at 823K. Then inorganic pores were modified\r\nwith metal-supported MSN with attention to the acidity, surface area, pore size, and ability of ion exchange. Crystalline size was\r\nshown to decrease up to 20 molar ratios of Si/Al followed by increasing while further adding nanoparticles-aluminium.Moreover,\r\nthe XRD patterns revealed the mesostructured material for all with 2D hexagonal structure. The obtained results from the XRD\r\npatterns were confirmed by using BET and EDX.The BET surface areas revealed the spherical shape for all samples with a decrease\r\nin the pore volume and surface area for various AlMSNs which emphasized that the loading of Al and was compatible with XRD\r\nresults. MSN was prepared by sol-gel methods followed by loading of Al in order to prepare AlMSN which possess strong Lewis\r\nacidic sites. This modification occurred by using various molar ratios of 0, 5, 10, 20, 50, and 100 Si/Al, respectively.The XRD patterns\r\nof various ratios of Si/Al were interpreted in terms of strain, nanocrystalline size, and distribution of the particle size by deriving\r\nWiliamson Hall equation....
Recent technology and experiments have fabricated high-quality superconducting MgB2 nanoparticles. We investigate properties\r\nof two-gap superconductivity in nanosized systems by using a two-sublevel model. In the present work, we analyze the results\r\nobtained for superconducting granules in the case of multiband superconductivity. We discuss the finite size effect in multiband\r\nsuperconductors. A definition of the critical level spacing of two-gap superconductivity is also presented, and we discuss the\r\ncondensation energy and the parity gap of two-gap superconductivity in relation to the size dependence of those properties with\r\ntwo bulk gaps and the effective pair scattering process between two sublevels....
Various concentrations of copper oxide were embedded into silica matrix of xerogel forms using copper source Cu(NO3)2�·3H2O.\r\nThe xerogel samples were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) with determination of\r\nnew molar ratios of the components by the sol-gel method. In this paper, three samples of copper oxide were doped into silica\r\nmatrices using different concentrations. We obtained 10, 20, and 30 wt.% of copper oxide in silica matrices labeled as A, B, and\r\nC, respectively. The absorption and transmittance spectra of the gel matrices were treated at different concentrations by Uv-vis\r\nspectrophotometer. Quantities of water and transparency in the silica network change the spectral characteristics of Cu2 ions in\r\nthe host silica. Absorption spectra of the samples heated to higher concentration complete the conversion of Cu2 ions to Cu\r\nions. The effects of concentration of copper oxide were characterized by X-ray diffraction (XRD) patterns, and the transmission\r\nelectron microscope (TEM) micrographs. Also, textural properties of samples were studied by surface area analysis (BET method)\r\nat different concentrations....
This paper reports the results of studies on the rheological behavior of nanocomposites of high density polyethylene (HDPE) with\r\npristinemultiwall carbon nanotubes (CNT) as well as phenol and 1-octadecanol (C18) functionalized CNT at 1, 2, 3, 4, 5, and 7 wt%\r\nloading. The viscosity reduction at 1 wt% CNT follows the order, pristine CNT < phenol functionalized CNT < C18 functionalized\r\nCNT. As the filler loading increases from 1 to 2, 3, and 4 wt%, neat HDPE and filled HDPE systems show similar moduli and\r\nviscosity, particularly in the low frequency region. As the filler loading increases further to 5 and 7 wt%, the viscosity and moduli\r\nbecome greater than the neatHDPE.Thestorage modulus, tan??, and the Cole-Cole plots show that CNT network formation occurs\r\nat higher CNT loading. The critical CNT loading or the rheological percolation threshold, where network formation occurs is\r\nfound to be strongly dependant on the functionalization of CNT. For pristine CNT, the rheological percolation threshold is around\r\n4 wt%, but for functionalized CNT it is around 7 wt%. The surface morphologies of CNT and functionalized CNT at 1 wt% loading\r\nshowed good dispersion while at 7 wt% loading, dispersion was also achieved, but there are few regions with agglomeration of\r\nCNT....
Silver p-tolylacetylide is an achiral molecule; however, its nanostructure has been found to consist of twisted nanoribbons. The\r\ntwisted ribbon is a helicoid that combines translation and perpendicular rotation along the ribbon axis. A helix, a typical chiral\r\nstructure, can be created by the aggregation of achiral molecules, and the recrystallization conditions control the twist of the\r\nnanoribbons. Therefore, the recrystallization controls the chirality....
Comparative studies are presented of iron oxide nanoparticles in the 7ââ?¬â??15nm average diameter range ball milled in hexane in the\r\npresence of oleic acid. Transmission electron microscopy identified spherical particles of decreasing size as milling time and/or\r\nsurfactant concentration increased. Micromagnetic characterization via MÃ?¨ossbauer spectroscopy at room temperature yielded\r\nbroadened magnetic spectroscopic signatures, while macromagnetic characterization via vibrating sample magnetometry of 7-\r\n8 nm diameter particles showed largely superparamagnetic behavior at room temperature and hysteretic at 2K. Zero-field and\r\nfield-cooled magnetization curves exhibited a broad maximum at ~215K indicating the presence of strong interparticle magnetic\r\ninteractions.The specific absorption rates of ferrofluids based on these nanoparticle preparations were measured in order to test\r\ntheir efficacies as hyperthermia agents...
Titanium dioxide (TiO2) nanoparticles are widely used in electronics, biology, andmedicine owing to their special properties.However,\r\nduring TiO2 nanoparticles exposure, nanoparticles may enter the blood circulation and translocate to the heart, and they may\r\nresult in negative effects on the cardiovascular system. In this study, we demonstrated that the anatase and rutile TiO2 nanoparticles\r\nhad potential toxicological effects on primary cultured cardiac myocytes of rat. After incubating with the anatase and rutile TiO2\r\nnanoparticles, the primary cultured cardiac myocytes had become elongated and appeared to detach from the surface of cell plate.\r\nAfter exposure to 50, 100, and 150 ??g/mL anatase and rutile TiO2 nanoparticles for 2 days, the obvious decrease of cell viability\r\nwas observed. And further studies showed that TiO2 nanoparticles exposure could induce the high expression of proinflammatory\r\ncytokines TNF-?? and IL-6, especially in 150 ??g/mL group. The long-rod rutile TiO2 had more strong effects on cell viability and\r\nproinflammatory cytokines induction than red-blood cells like anatase TiO2. Results indicated that TiO2 nanoparticles exposure\r\ncould impair the function of primary cultured cardiac myocytes of rat. Therefore, these findings support the view that much more\r\nattention should be aroused on the application of these nanoparticles and their potential exposure effects on human beings....
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