Bulk or macroscopic

Consider the cooling of a hot block by blowing cool air over its tdp surface (Fig. 1-32). Heal is first transferred to the air layer adjacent to the block by conduction. This heat is then carried away from the surface by convection, that is, by the combined effects of conduction within the air that is due to random motion of air molecules and the bulk or macroscopic motion of the air that removes the heated air near the surface and replaces it by the cooler air. 

Thus the plot of polarization as a function of the applied field is a straight line whose slope is the linear polarizabilty, a, of the molecule or atom. If the field oscillates with a frequency, then the induced polarization will have the same frequency and phase, if the response is instantaneous. Most applications of experiments with NLO are carried out on bulk or macroscopic materials and in this case, the linear polarization can be defined as... 

There is also a distinction to be drawn between nanoscience and nanotechnology. Nanoscience is the sub-discipline of science that involves the study of nanoscale materials, processes, phenomena and/or devices. Nanoscience includes materials and phenomena at the nanoscale (typically 0.1-100 nm) hence, it includes areas such as carbon nanoscience (e.g. fullerenes), molecular scale electronics, molecular self-assembly, quantum size effects and crystal engineering. Nanotechnology involves the design, characterization, manipulation, incorporation and/or production of materials and structures in the nanoscale range. These applications exploit the properties of the nanoscale components, distinct from bulk or macroscopic systems. Naturally, there is a substantial overlap of scale between nanotechnology and colloid technology. 

Most measurements of rates of chemical reactions are made on bulk systems in which the reacting molecules are distributed over a range of energy states (cf. Fig. 1). Some theories of reaction rates therefore focus on the bulk, or macroscopic, systems. This requires them to be statistical treatments. 

Like all physical matter, a fluid is composed of an extremely large number of molecules per unit volume. A theory such as the kinetic theory of gases or statistical mechanics treats the motions of molecules in terms of statistical groups and not in terms of individual molecules. In engineering we are mainly concerned with the bulk or macroscopic behavior of a fluid rather than with the individual molecular or microscopic behavior. 

Here p, Po, and E are vectors and a, and y tensors, normally referred to as polarizability, hyperpolarizability and second order hyperpolarizability, respectively. Similarly, the polarization in bulk or macroscopic media is given by ... 

So far, we have considered bulk or macroscopic mass transport measurements which involve an averaged value of and hence A for the entire electrode. However, all practical electrodes will have a non-uniform distribution of i, due to factors such as ... 

The molecular polarizabilities obtained in the last two sections are microscopic parameters that characterize an individual molecule. To relate them to the bulk or macroscopic parameters, namely, the susceptibihties and so forth, one... 

To look for possible answers to these questions we recall that classical thermodynamics deals with the bulk, or macroscopic, properties of matter. It does not consider its molecular structure. Internal energy and entropy, for example, are defined completely independently of any molecular considerations. (The reason why we have used, on certain occasions, such considerations was to gain some insight, not because they were needed per se). 

The focus of the present chapter is the application of second-order nonlinear optics to probe surfaces and interfaces. In this section, we outline the phenomenological or macroscopic theory of SHG and SFG at the interface of centrosymmetric media. This situation corresponds, as discussed previously, to one in which the relevant nonlinear response is forbidden in the bulk media, but allowed at the interface. 

The nnclei and the elements of new phase generated from them (gas babbles, metal crystallites) are macroscopic entities their nnmber on the surface is limited (i.e., they emerge not at all surface sites but only at a limited number of these sites). Hence, the primary products should move (by bulk or surface diffusion) from where they had been prodnced to where a nucleus appears or grows. 

Bulk or free water and gas are in the macroscopic pores with a hydraulic diameter greater than 0.1 fim. The gel pores are filled with pore solution (gel water). Their diameter is much smaller (1 - 30 nm). During cooling below the freezing point of bulk water ice is formed in the larger pores with sufficient su-... 

Nanotechnology is therefore essentially about understanding and manipulating materials at the atomic, molecular, and macromolecular level in a way that imparts properties to the material that would otherwise not exist either as individual atoms or as bulk processed macroscopic systems. 

Mesoporous materials were originally synthesized in irregular bulk or powder forms, which could limit their applications in separation, optics, electronics, and so on. Thus, it is highly desirable to produce mesoporous materials with controllable macroscopic forms. So far, mesoporous materials have been synthesized in a variety of forms including thin films, spheres, fibers, monoliths, rods, single crystals, and nanoparticles. The acidic synthetic route (S+X I+) developed by Huo etal. appears to be the most appropriate for the morphological control of mesostmctures. 

One of the major motivations for the study of nano-aggregate formation, either in bulk or in solution, is because it provides an opportunity to construct macromolecular objects with dimensions significantly larger than molecular dimensions, and therefore would pave the way to further organize them well into the macroscopic domain. Thus, this serves as a step-wise approach to organizing macromolecules in the bulk phase, with a control over the molecular organization at each step along the way. The fixation of the mushroom-shaped supramolecular ag-... 

In this chapter, we discuss the thermodynamic properties of surface phases. In the previous chapters we have assumed that heterogeneous systems consist of a number of completely homogeneous phases separated by sharply defined mathematical surfaces. It is clear from either molecular or macroscopic considerations that this assumption cannot rigorously apply. Molecules in the vicinity of the interface between any two phases experience a different environment from molecules in the bulk of the phases. Thus, the densities of the various components and the densities of energy and entropy in the vicinity of the interface will be different from the corresponding densities in the bulk phases. However, the influence of the interface does not extend for more than a few molecular dimensions (about 10 cm) into the phases, and the phases may therefore be assumed to be uniform except in the immediate neighborhood of the interfaces. The interface between two phases is in reality a thin region in which the physical properties vary continuously from the bulk properties of one phase to the bulk properties of the other phase. 

Hardness is a measure of a material s ability to resist elastic and plastic deformation. The hardness of non-ideal material is determined by the intrinsic stiffness of the material, as well as by the nature of its defects, be they point defects, dislocations, or macroscopic defects such as microcracks etc. For ideal systems, the hardness of a material will scale with its bulk modulus. 

We will here focus on nanoparticles as a typical example of nano-carriers. Nanoparticles can be seen as sub-micron colloidal objects with a predominantly elastic mechanical behaviour (solid-like bodies), which can be loaded with therapeutically active compounds on their surface, in their bulk or both. Drug-loaded nanoparticles have been administered as nano-carriers in water-based dispersions through virtually all parenteral routes, i.e., intravenous, subcutaneous, intramuscular and also intraperitoneal, but they have also been used to prepare macroscopic materials in situ (Fig. 12.1). 

So far, we have discussed the properties of soft shape-memory materials as a function of their nanoarchitectonics. At the same time, material microarchitectonics, also known as material forms, should be tailored to specific applications as SME in material was generally treated with bulk phenomenon. As such, designing an SMP object at the submicron to microscale is challenging. In particular, the synthesis of well-regulated nanoscale structures built up as meso- or macroscopic materials remains challenging. Recent rapid evolution in SMPs has been developed in efforts to meet various requirements in diverse potential applications. As a result, not only traditional film, tube, and sponge (foam) forms, but also microparticles, surface as well as micro/nanofiber that exhibit SMEs at mesoscopic to microscopic scales, have attracted much attention (Fig. 5.2.4). 

Until very recently, the theoretical evaluation of the effect of the medium on the behavior and properties of molecules was beyond the reach of quantum mechanical computations, essentially due to the prohibitive size of the systems which would have to be considered. Thus the habit evolved to treat essentially the isolated molecule and be satisfied by qualitative considerations or, at best, approximate evaluations of the bulk effect of the medium following early models [l]-[3]. The last few years have seen a number of attempts at a refinement of these continuum or macroscopic representations [4, 5, 6, 7]. One constant and essential inconvenience of these models is, however, the absence of precision concerning the arrangement of the solvation layer(s) around the solute, which is considered as residing in a cavity (generally spherical) embedded in a polarizable dielectric. No information is obtainable in this way about the details of the short-range solute-medium interactions. 

In order to fully explain the way in which molecular level structures and interactions bridge to macroscopic liquid-state properties, Voth stressed that a wide range of length and timescale calculations are required to predict different properties, like the interfacial tension, selfdiffusion and viscosity [30]. Both Voth and Borodin demonstrated the necessity of using polarisable force fields to accurately predict several properties of ionic liquids and their mixtures, namely, the transport of ionic species in the bulk or at metallic interfaces [96]. 

As it has been noted above, the main feature of polymers is that they consist of long chain macromolecules. Therefore, it is to be expected that polymer chains structure and their characteristics will be influenced essentially on bulk polymers properties. One of such polymer chain structural factors is availability in it of bulk side groups, which results to bulk polymers brittleness enhancement [40], A side groups effect on plasticity level for heterochain polymers was considered in Ref. [41], where brittleness increase was explained by side groups nonparticipation in local or macroscopic plasticity processes. 

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