Macroscopic and microscopic

Tabor M, Levine R D, Ben-Shaul A and Steinfeld J I 1979 Microscopic and macroscopic analysis of non-linear master equations vibrational relaxation of diatomic molecules Mol. Phys. 37 141-58... 

Figure C2.7.10. Rates of reaction of CO with O on Pt(l 11), detennined from microscopic ( ) and macroscopic (+) ( text for details 1121.

Tlie microscopic and macroscopic properties of asbestos fibers stem from their intrinsic, and sometimes unique, crystalline features. As with all siUcate minerals, the basic building blocks of asbestos fibers are the siUcate tetraliedra wliicli may occur as double chains, as in the ampliiboles, or in... 

The typical industrial catalyst has both microscopic and macroscopic regions with different compositions and stmctures the surfaces of industrial catalysts are much more complex than those of the single crystals of metal investigated in ultrahigh vacuum experiments. Because surfaces of industrial catalysts are very difficult to characterize precisely and catalytic properties are sensitive to small stmctural details, it is usually not possible to identify the specific combinations of atoms on a surface, called catalytic sites or active sites, that are responsible for catalysis. Experiments with catalyst poisons, substances that bond strongly with catalyst surfaces and deactivate them, have shown that the catalytic sites are usually a small fraction of the catalyst surface. Most models of catalytic sites rest on rather shaky foundations. 

Thus, there are rather many microscopic processes which contribute to result in hydrogen-improved workability. To elucidate all contributions to this beneficial phenomenon, further study of the plastic flow of titanium alloys is necessary both at microscopic and macroscopic levels. 

Me/a/—composition, detailed atomic structure, microscopic and macroscopic heterogeneities, stress (tensile, compressive, cyclic), etc. 

Heterogeneities associated with a metal have been classified in Table 1.1 as atomic see Fig. 1.1), microscopic (visible under an optical microscope), and macroscopic, and their effects are considered in various sections of the present work. It is relevant to observe, however, that the detailed mechanism of all aspects of corrosion, e.g. the passage of a metallic cation from the lattice to the solution, specific effects of ions and species in solution in accelerating or inhibiting corrosion or causing stress-corrosion cracking, etc. must involve a consideration of the detailed atomic structure of the metal or alloy. 

In this section the interaction of a metal with its aqueous environment will be considered from the viewpoint Of thermodynamics and electrode kinetics, and in order to simplify the discussion it will be assumed that the metal is a homogeneous continuum, and no account will be taken of submicroscopic, microscopic and macroscopic heterogeneities, which are dealt with elsewhere see Sections 1.3 and 20.4). Furthermore, emphasis will be placed on uniform corrosion since localised attack is considered in Section 1.6. 

Iindg88a] Lindgren, K., Microscopic and macroscopic entropy . Physical Review 38A (1988) 4794-4798. 

To elucidate the distinction between the sub-microscopic and macroscopic worlds, Table 1.1 lists some observable chemical phenomena (the macroscopic level) along with the corresponding explanatory models that we use at the sub-microscropic level. 

Another example of the coupling between microscopic and macroscopic properties is the flexo-electric effect in liquid crystals [33] which was first predicted theoretically by Meyer [34] and later observed in MBBA [35], Here orientational deformations of the director give rise to spontaneous polarisation. In nematic materials, the induced polarisation is given by... 

The ability to create and observe coherent dynamics in heterostructures offers the intriguing possibility to control the dynamics of the charge carriers. Recent experiments have shown that control in such systems is indeed possible. For example, phase-locked laser pulses can be used to coherently amplify or suppress THz radiation in a coupled quantum well [5]. The direction of a photocurrent can be controlled by exciting a structure with a laser field and its second harmonic, and then varying the phase difference between the two fields [8,9]. Phase-locked pulses tuned to excitonic resonances allow population control and coherent destruction of heavy hole wave packets [10]. Complex filters can be designed to enhance specific characteristics of the THz emission [11,12]. These experiments are impressive demonstrations of the ability to control the microscopic and macroscopic dynamics of solid-state systems. 

The linkage of microscopic and macroscopic properties is not without challenges, both theoretical and experimental. Statistical mechanics and thermodynamics provide the connection between molecular properties and the behavior of macroscopic matter. Coupled with statistical mechanics, computer simulation of the structure, properties, and dynamics of mesoscale models is now feasible and can handle the increase in length and time scales. 

The building blocks of all materials in any phase are atoms and molecules. Their arrangements and how they interact with one another define many properties of the material. The nanotechnology MBBs, because of their sizes of a few nanometers, impart to the nanostructures created from them new and possibly preferred properties and characteristics heretofore unavailable in conventional materials and devices. These nanosize building blocks are intermediate in size, lying between atoms and microscopic and macroscopic systems. These building blocks contain a hmited and countable number of atoms. They constitute the basis of our entry into new realms of bottom-up nanotechnology [97, 98]. 

Periphyton are microscopic and macroscopic algae that attach to and grow on solid surfaces, such as lake bottoms, rooted aquatic vegetation, and submerged woody debris. Periphyton form part of the base of littoral food webs in lakes. Periphyton communities are taxonomically diverse and the attached communities contain other organisms, such as bacteria and zooplankton, as well as detrital material. Periphyton vary seasonally and annually in both abundance and species composition. 

The combination of microscopic and macroscopic information is made possible by what can be called parameter imaging . In the general sense, it consists of the encoding of properties such as spectral line shifts, relaxation times, diffusion coefficients, etc., in the image by suitable combination of corresponding modules into one pulse sequence. Parameter images are to be distinguished from mere... 

In physical chemistry the most important application of the probability arguments developed above is in the area of statistical mechanics, and in particular, in statistical thermodynamics. This subject supplies the basic connection between a microscopic model of a system and its macroscopic description. The latter point of view is of course based on the results of experimental measurements (necessarily carried out in each experiment on a very large number of particle ) which provide the basis of classical thermodynamics. With the aid of a simple example, an effort now be made to establish a connection between the microscopic and macroscopic points of view. 

Figure 2. Asphaltene structure deduced from microscopic and macroscopic analysis, showing their micro- and macro-molecular bonding. T. F. Yen, 1972, first suggested this type of structure.

Feedback provided by on-line monitoring of self-assembling processes will play an increasingly important role in controlling the microscopic and macroscopic architecture of molecular assemblies. Successful adaptation of char-... 

Although there is a distribution of residence times, the complete mixing of fluid at the microscopic and macroscopic levels leads to an averaging of properties across all fluid elements. Thus, the exit stream has a concentration (average) equivalent to that obtained as if the fluid existed as a single, large fluid element with a residence time of t = V/q (equation 2.3-1). 

Note that, compared to conventional liquid solvents, SCFs are not always a panacea. They have both merits and disadvantages. Many chemical reactions are better performed in ordinary fluid solutions. However, chemistry of the reaction in SCFs still is a young and fully unexplored scientific field. We need deeper understanding of the microscopic and macroscopic properties of SCFs. The industrial... 

Figure 24, presented originally by Belton (1995), illustrates the enormous range in distance scales that can be probed using various magnetic resonance spectroscopy and imaging techniques. Approximate distance ranges for molecular, microscopic, and macroscopic regions are provided for perspective on the left side of Figure 24. The criterion used for the demarcation between macroscopic and microscopic regions was based on the size of objects that are no longer visible with the naked or unaided eye, i.e., less than 40 xm (Hills, 1998).

In general, heterogeneities in structural materials are often the source of mechanical failure, but specific types also provide ways to disperse energy without failure. For example, some silks, at a microscopic and macroscopic level, are able to form structures such as spherulite inclusions that will develop into elongated cavities in the solid fibers (Akai, 1998 Frische et al., 1998 Robson, 1999 Tanaka et al., 2001). Interestingly, Isobe et al. (2000), in a significant but largely overlooked paper, showed that synthetic A/ i 4o produced spherulites that had the essential features of Alzheimer s amyloid senile plaques (Kaminsky et al., 2006). 

The first satisfactory explanation of these effects was given, in the twenties, by Debye, Hiickel, Onsager, and Falkenhagen (see, for instance, Ref. 8). Using a remarkably clever combination of microscopic and macroscopic concepts, they were able to describe the behavior of dilute electrolytes by the famous limiting laws . 

Onda M, Yoshihara K, Koyano H, Ariga K, Kunitake T (1996) Molecular recognition of nucleotides by the guanidinium unit at the surface of aqueous micelles and bilayers. A comparison of microscopic and macroscopic interfaces. J Am Chem Soc 118 8524-8530... 

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