Nanometer effect

Currently, the applications of the regularities of nanoscience in the catalyst structure are the nanoclusters composed of either atoms or ions, which play an important role in improving the catalyst properties. The developments and conservations of such kind of nanoclusters require the deep backgrounds of solid state chemistry, which is the main target for any of catalyst producers. 

The modern industrial iron catalyst is a nanostructured metastable substance, which is formed during the surprisingly complex synthesis of the oxide precursor. 

Though the nanoscience concepts have been applied in industrial catalysis since its beginning, the catalyst research workers should be clear-headed and recognize that, the attentions of many in the past, was mainly focused on the size effect of materials, while, there are even more of interests in the nanosciences in addition to the size effect, that the surface effect and the quantum effect and from which the produced particularly excellent properties such as mechanics, optics, magnetism and calorifics. 

The surface effect refers to the consumedly increase of the ratios between surface atoms and total atoms, the surface energies and surface tensions of the particles with the decrease of the sizes of nanoparticles, which then result in the changes of the nature of nanoparticles. The crystal field and binding energy of the surface atoms in nanoparticles are somewhat different from that of the inner atoms, where in the former case, numerous dangling bonds are present and with the unsaturations these surface atoms are extremely easy to bond with other atoms in order to stabilize. Hence, the surface atoms have the very high chemical activities. 

The surface area of spherical particle is in proportion to the square of its diameter, while its volume is in direct proportion to the cube of the diameter. Hence, the specific surface area (surface area/volume) is in inverse proportion to the diameter, namely, the specific surface area increases strikingly as the particle diameter becomes smaller, as shown in Table 3.27. 

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Liu, J., Zhao, Z., Xu, C., etal. (2010). Ce02-supported Vanadium Oxide Catalysts for Soot Oxidation The Roles of Molecular Structure and Nanometer Effect, J. Rare Earths, 28, pp. 198-204. 

A similar effect occurs in highly chiral nematic Hquid crystals. In a narrow temperature range (seldom wider than 1°C) between the chiral nematic phase and the isotropic Hquid phase, up to three phases are stable in which a cubic lattice of defects (where the director is not defined) exist in a compHcated, orientationaHy ordered twisted stmcture (11). Again, the introduction of these defects allows the bulk of the Hquid crystal to adopt a chiral stmcture which is energetically more favorable than both the chiral nematic and isotropic phases. The distance between defects is hundreds of nanometers, so these phases reflect light just as crystals reflect x-rays. They are called the blue phases because the first phases of this type observed reflected light in the blue part of the spectmm. The arrangement of defects possesses body-centered cubic symmetry for one blue phase, simple cubic symmetry for another blue phase, and seems to be amorphous for a third blue phase. 

The development of mote intense sources (eg, plasma sources, soft x-ray lasers, and synchrotron sources) has made possible highly effective instmments both for x-ray microscopy and x-ray diffraction on a few cubic nanometer sample. The optical problem of focusing x-rays is accompHshed by the use of zone plates or by improved grazing incidence or multilayer reflectors. 

Wahl, K.J., Stepnowski, S.V. and Unertl, W.N., Viscoelastic effects in nanometer-scale contacts under shear. Tribal. Lett., 5, 103-107 (1998). 

The scale of the microscopic surface roughness is important to assure good mechanical interlocking and good durability. Although all roughness serves to increase the effective surface area of the adherend and therefore to increase the number of primary and secondary bonds with the adhesive/primer, surfaces with features on the order of tens of nanometers exhibit superior performance to those with features on the order of microns [9,14], Several factors contribute to this difference in performance. The larger-scale features are fewer in number... 

Carbon nanotube research was greatly stimulated by the initial report of observation of carbon tubules of nanometer dimensions[l] and the subsequent report on the observation of conditions for the synthesis of large quantities of nanotubes[2,3]. Since these early reports, much work has been done, and the results show basically that carbon nanotubes behave like rolled-up cylinders of graphene sheets of bonded carbon atoms, except that the tubule diameters in some cases are small enough to exhibit the effects of one-dimensional (ID) periodicity. In this article, we review simple aspects of the symmetry of carbon nanotubules (both monolayer and multilayer) and comment on the significance of symmetry for the unique properties predicted for carbon nanotubes because of their ID periodicity. 

High-resolution transmission electron microscopy (HREM) is the technique best suited for the structural characterization of nanometer-sized graphitic particles. In-situ processing of fullerene-related structures may be performed, and it has been shown that carbonaceous materials transform themselves into quasi-spherical onion-like graphitic particles under the effect of intense electron irradiation[l 1],... 

In modern materials science topics of high interest are surface structures on small (nanometer-length) scales and phase transitions in adsorbed surface layers. Many interesting effects appear at low temperatures, where quantum effects are important, which have to be taken into account in theoretical analyses. In this review a progress report is given on the state of the art of (quantum) simulations of adsorbed molecular layers. 

As is known, microscale friction and wear is important in microtribology. However, it is not easy to get real friction force on micro/nano scale during the tests. The surface morphology at nanometer scale, the scanning direction of the FFM, etc., have significant effects on friction force measurement. Even nowadays for commercial SPM we are not quite sure if the friction force we get is a real one or not. 

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