Nanoceramics

Nalidixic acid, 3 29 21 104, 123, 215 year of disclosure or market introduction, 3 6t N-alkylation reactions of aniline, 2 785-786 microwaves in, 16 557-558 Naltrexone drug delivery, 9 65—66 Nameplate capacities, 23 547-548 Nametre viscometer, 21 739 NAND arrays, 22 258 Nanoaluminum composites, 10 19, 20 Nanoassemblies, shell and core cross-linked, 20 489-490 Nanocar, 24 62 Nanocarbon materials, 1 718-722 Nanoceramics, 1 705-708 Nanoclays, 11 313-314... 

Aronove, D., Karlov, A., and Rosenman, G. (2007). Hydroxyapatite nanoceramics Basic physical properties and biointerface modification. ]. Eur. Ceram. Soc. 27, 4181-4186. 

Nanocrystalline materials form an exciting area of materials research because bulk materials with grain size less than 100 nm have properties not seen in their microcrystalline counterparts. But the brittleness of nanoceramics has limited their potential for use in structural applications, namely, research on nanoceramics shows that they are not inherently tougher than their microcrystalline counterparts. Many strategies have been proposed to improve the mechanical properties of nanoceramics by using reinforcement by a second-phase addition and hybridization to develop nanocrystalline matrix composite materials. 

According to the equation, the diffusional creep rate of a polycrystal may be enhance by reducing the crystal size cl, and by increasing the boundary diffusivity I. Nanoceramics are therefore expected to exhibit enhanced diffusional creep for two reasons first, the reduction of the crystal size from about 10 pm to -10 nm enhances the creep rate by a factor of 109, and second, the enhanced boundary diffusivity may increase the creep rate by 103, so that the total enhancement is 1012. 

It is noted, however, that both of the above CaF2 and Ti02 nanoceramics had some amount of porosity. This may account for an apparent soft behavior related to the superplastic deformation at low temperature, which does not yet reveal the plastic deformation characteristics in nanoceramics. Localized superplastic deformation under cyclic tensile fatigue tests was observed by Yan et al. on 3Y-TZP nanoceramics at room temperature [25], The micromechanism behind this phenomenon is argued to be essentially governed by grain-boundary diffusion. The contribution of dislocation slip might be in operation as a parallel mechanism to develop slip band-like microfeatures. 

Zhan, G.-D., Kuntz, J.D., Garay, J.E. and Mukherjee, A.K., Electrical properties of nanoceramics reinforced with ropes of single-walled carbon nanotubes , Appl. Phys. Lett., 2003, 83, 1228-1230. 

On the other hand, improvements in ceramic powder processing technology, the routine preparation of high-purity ceramics of nanometre scale, and the new techniques for the processing of these powders such as HIP, SPS, microwave furnace, etc., will be the driving forces for a very active study on nanoceramics in the near future, probably opening up new phenomena and new applications. 

Investigations of the underlying mechanism(s) revealed that the concentration, conformation, and bioactivity of vitronectin (a protein contained in serum that is known to mediate osteoblast adhesion ((Thomas et al., 1997) see the section Vitronectin ) was responsible for the select, enhanced adhesion (a crucial prerequisite for subsequent, anchorage-dependent-cell function) of osteoblasts on these novel nanoceramic formulations. Specifically, of the proteins (such as albumin, laminin, fibronectin, collagen, and vitronectin) tested, vitronectin adsorbed in the highest concentration on nanophase alumina after 4 hr moreover, competitive adsorption of vitronectin was 10% greater on nanophase compared to conventional alumina (Webster et al.,... 

It is imperative to determine properties of nanoceramics that enhance osteoblast and osteoclast functions Webster et al. (2000a,b, 2001 a,b) proposed the following ... 

Due to their ability to selectively promote both osteoblast and osteoclast function, nanophase ceramics provide a preferable alternative to conventional orthopedic and dental implants that fail to integrate with surrounding bone it is undoubtedly highly desirable to minimize, if not avoid, clinical complications that necessitate removal of failed implants as a result of poor surface properties that lead to insufficient osseointegration. These results provide evidence that nanoceramics may be synthesized to match surface properties of bone and, thus, demonstrate strong promise and potential for their use in orthopedic and dental applications. 

Keywords nanotechnology, nanomaterials, molecular layering method, adsorbents, catalysts, nanoceramic, nanocomposition materials, pigments, nanofillers, polymers, retardants of combustibility... 

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