Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 6 Articles
This paper focuses on presenting the forefront of the interdisciplinary studies conceived towards the generation of the wear particles\r\naerosol when materials are subjected tomechanical stresses. Various wearmechanisms and instrumentation involved during stress\r\napplication and aerosolization of wear particles, as well as particles characterization, measurement, and modeling techniques are\r\npresented through the investigation of a series of contextual works which are emphasized on the identification of these aspects.\r\nThe review ismotivated fromthe fact that understandingmechanisms involved in wear-induced particle generation, both at nanoand\r\nat microscale, is important for many applications that involve surfaces sliding over each other due to various potential health\r\naspects. An attempt has been made to explain how the information based on this broad spectrum of subjects discovered in this\r\ncontribution can be used and improved in order to produce a more resilient, rational, and versatile knowledge base which has\r\nbeen found lacking in the present literature during its survey. The area of study is highly multidisciplinary since it involves aerosol,\r\nparticle, and material sciences....
The influence of biomimetic calcium phosphate coating on osteoblasts behavior in vitro is not well established yet. In this study,\r\nwe investigated the behavior of osteoblastic rat osteosarcoma 17/2.8 cells (ROS17/2.8) on two groups of biomaterial surfaces:\r\nalkaline-treated titanium surface (ATT) and biomimetic calcium phosphate coated ATT (CaP). The cell attachment, proliferation,\r\ndifferentiation, andmorphology on these surfaceswere extensively evaluated to reveal the impact of substrate surface on osteoblastic\r\ncell responses. It was found that the ROS17/2.8 cells cultured on the ATT surface had higher attachment and proliferation rates\r\ncompared to those on the CaP surface. Our results also showed that the calcium phosphate coatings generated in this work have\r\nan inhibiting effect on osteoblast adhesion and further influenced the proliferation and differentiation of osteoblast compared to\r\nthe ATT surface in vitro. Cells on the ATT surface also exhibited a higher alkaline phosphatase activity than on the CaP surface\r\nafter two weeks of culture. Immunofluorescence staining and scanning electron microscopy results showed that the cells adhered\r\nand spread faster on the ATT surface than on the CaP surface. These results collectively suggested that substrate surface properties\r\ndirectly influence cell adhesion on different biomaterials, which would result in further influence on the cell proliferation and\r\ndifferentiation....
Neural cell adhesion and neurite outgrowth were examined on graphene-based biomimetic substrates. The biocompatibility of\r\ncarbon nanomaterials such as graphene and carbon nanotubes (CNTs), that is, single-walled and multiwalled CNTs, against\r\npheochromocytoma-derived PC-12 neural cells was also evaluated by quantifying metabolic activity (with WST-8 assay),\r\nintracellular oxidative stress (with ROS assay), and membrane integrity (with LDH assay). Graphene films were grown by using\r\nchemical vapor deposition and were then coated onto glass coverslips by using the scooping method. Graphene sheets were\r\npatterned on SiO2/Si substrates by using photolithography and were then covered with serum for a neural cell culture. Both types\r\nof CNTs induced significant dose-dependent decreases in the viability of PC-12 cells, whereas graphene exerted adverse effects\r\non the neural cells just at over 62.5 ppm. This result implies that graphene and CNTs, even though they were the same carbonbased\r\nnanomaterials, show differential influences on neural cells. Furthermore, graphene-coated or graphene-patterned substrates\r\nwere shown to substantially enhance the adhesion and neurite outgrowth of PC-12 cells. These results suggest that graphene-based\r\nsubstrates as biomimetic cues have good biocompatibility as well as a unique surface property that can enhance the neural cells,\r\nwhich would open up enormous opportunities in neural regeneration and nanomedicine....
An adsorbent called chitosan coated magnetic hydroxyapatite nanoparticles (CS-MHAP) was prepared with the purpose of\r\nimprovement for the removal of Ni2+ ions and textile dye by coprecipitation. Structure and properties of CS-MHAP were\r\ncharacterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),\r\nand vibrating sample magnetometer (VSM). Weight percent of chitosan was investigated by thermal gravimetric analysis (TGA).\r\nTheprepared CS-MHAP presents a significant improvement on the removal efficiency ofNi2+ ions and reactive blue 19 dye (RB19) in\r\ncomparison with chitosan and magnetic hydroxyapatite nanoparticles.Moreover, the adsorption capacities were affected by several\r\nparameters such as contact time, initial concentration, adsorbent dosage, and initial pH. Interestingly, the prepared adsorbent could\r\nbe easily recycled from an aqueous solution by an external magnet and reused for adsorption with high removal efficiency....
Au and Ag nanoparticles embedded in amorphous Al2O3 matrix are fabricated by the pulsed laser deposition (PLD) method\r\nand rapid thermal annealing (RTA) technique, which are confirmed by the experimental high-resolution transmission electron\r\nmicroscope (HRTEM) results, respectively. The strain distribution of Au and Ag nanoparticles embedded in the Al2O3 matrix is\r\ninvestigated by the finite-element (FE) calculations.The simulation results clearly indicate that both the Au and Ag nanoparticles\r\nincur compressive strain by the Al2O3 matrix. However, the compressive strain existing on the Au nanoparticle is much weaker\r\nthan that on the Ag nanoparticle. This phenomenon can be attributed to the reason that Young�s modulus of Au is larger than that\r\nof Ag.This different strain distribution of Au and Ag nanoparticles in the same host matrix may have a significant influence on the\r\ntechnological potential applications of the Au-Ag alloy nanoparticles....
This work analyzes the effect of nanosecond laser pulse deposition of GaAs in an inert atmosphere of Ar and He.The number of\r\npulses and the gas pressure were varied and the effect on the nanoparticles formation was studied by scanning electron microscopy,\r\ngrazing incidence small angle X-ray scattering, and atomic force microscopy. It is shown that the GaAs nanoparticle sizes and size\r\ndistributions can be controlled partly by the number of laser pulses applied during their production and partly by the choice of\r\ninert gas and its pressure. Our results suggest that He is a more promising working gas producing narrower size distributions and\r\na better size control of the grown nanoparticles...
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