Nano-silica generation

In terms of green composite or bio-composite, the sol-gel sihca can be applied to natural fibres. An earlier work reports the generation of sihca into the voids of kenaf fibre about 20% of nano-silica could be incorporated into the fibre. Figure 7.2 showed the incorporation of sol-gel silica in the void of kenaf fibres. The kenaf sol-gel silica mixture could be used to prepare bio-composites or green composites by choosing the right polymer matrices. 

Carbon nanotubes (CNTs) currently attract intense interest because of their unique properties which make them suitable for many industrial applications.28 Carbon nanotubes exhibit some of the properties implied in asbestos toxicity. Carbon nanotubes share with asbestos the fibrous habit - long fibers with a diameter of a few nanometers -and a very high biopersistence. On this basis they are suspected to be hazardous and indeed the first studies in vivo14,29,30 have shown an inflammatory response followed by some evolution towards fibrosis. When inhaled, CNTs may thus constitute a possible hazard to human health. The inflammatory and fibrotic responses elicited by CNTs is similar to that caused by other toxic particles which might be the result of oxidative stress caused by particle- and/or cell-derived free radicals. There is no direct experimental evidence of a capacity of carbon nanotubes to generate free radicals similar to silica asbestos and nano sized iron oxide particles. 

In order to reduce peak broadening in the nano-ESI needle attached to the nano-LC column, the use of packed needles has been promoted. Gatiin et al. [58] reports the use of 100-pm-ID fused-silica in-needle packed columns (10-pm particles) with a laser-pulled tip with a diameter of -2 pm. Figeys and Aebersold [59] reported the use of such in-needle RPLC columns for the LC-MS analysis of tryptic digests in combination with a nucrofluidic device to generate a nanoflow solvent gradient via electroosmotic flows. 

Metal Surface Composition To determine which metal bound to surfaces of road dust, soil dust was collected that contained larger particles (400 to 3000 nm diameter in air) and that compared closely to amorphous silica dust (6, 7). This dust was thought to be composed of both particles ground from the Earth s emst and particles generated by transportation vehicles that drive on the roads from which road dust was collected. Dust was collected near a road in four fractions. <56 nm, <100nm, both ultrafine (nano) particle aerosols, a fraction <2500 nm (a fine aerosol), and one < 10,000 nm (a coarse aerosol). Different elements were enriched on the surface of different-sized particles (6, 7). 

Stable and efficient ESI, and thus sensitive MS detection, is most easily accomplished from very sharp emitters (2-10 p,m i.d. x 5-20 ttm o.d.) fabricated from pulled fiised-silica capillaries, that operate at an optimum flow rate of 20-50 nL/min and relatively low ESI on-set voltage (800-1800 V). These are the typical nano-ESI emitters that enable the much desired amol and zmol detection limits. To achieve similar performance, such emitters have been inserted in the chip either through the edge of the chip, directly in the channel terminus, or perpendicular to the chip, through an orifice that was communicating with one of the channels on the chip. Flow generation and stabilization in these chips was accomplished by various approaches. 

Based on colloidal monolayers of polystyrene spheres, we have prepared various two-dimensional nano-structured arrays by solution routes and electrodeposition. Many ordered structured arrays generated using these methods are of surface roughness on the nano- and micro-scales, and could be superhydrophobic or superhydrophilic. The nano-devices based on such nano-structured arrays would be waterproof and selfcleaning, in addition to their special device functions. In this article, taking silica, ZnO and gold as examples of the insulators, semiconductors and metals, respectively, we report some of our recent results to demonstrate controlled wettability and superhydrophobicity of two-dimensional ordered nano-stmctured arrays with centimeter square-size based on colloidal monolayers. 

New generation nano scale fillers are challenging the domination of traditional fillers such a as carbon blacks and silica in the mbbery industry. Nanoscaled fillers such as layered silicates, carbon nanotubes, carbon nanofibers (CNFs), exfoliated graphite, spherical particles and Polyhedral oligomeric silsesquioxane (POSS), etc. dispersed as a reinforcing phase in a mbber matrix are emerging as a relatively new form of usefiil material. 

Another instrumental development is based on the fact that the generation of smaller droplets is more favorable in terms of droplet evaporation during ESI, of sensitivity and the abihty to preserve non-covalent molecular associates. Thus, nanoelectrospray ionization (nESI) has been developed [68], where the analyte is sprayed from a gold-coated fused-silica capillary with a tip diameter of 1-5 pm rather than from capillaries with a 100-150-pm tips that are used in conventional (pneumatically assisted) ESI. In nESI, flow-rates as low as 20 nl/min can be nebulized. Thus, gentler operating conditions (temperature, gas flows, needle voltage) can be achieved. In order to more readily implement nESI in LC-MS operation, integrated chip-based nano-LC-nESI devices have also been developed [69]. 

Y. Yin, Y. Lu, Y. Sun and Y. Xia, Silver nanowires can be directly coated with amorphous silica to generate well-controlled coaxial nanocables of silver/silica, Nano Lett. 2(4), (2002). 

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