Microscopic distribution

The physical process of melt ascent during two-phase flow models is typically based on the separation of melt and solid described by Darcy s Law modified for a buoyancy driving force. The melt velocity depends on the permeability and pressure gradients but the actual microscopic distribution of the melt (on grain boundaries or in veins) is left unspecified. The creation of disequilibria only requires movement of the fluid relative to the solid. 

Taylor GN, Jee WSS, Dockum N, et al. 1969. Microscopic distribution of americium-241 in the beagle thyroid gland. Health Phys 17 723-725. 

Early theories of Guth, Kuhn, Wall and others proceeded on the assumption that the microscopic distribution of end-to-end vectors of the chains should reflect the macroscopic dimensions of the specimen, i.e., that the chain vectors should be affine in the strain. The pivotal theory of James and Guth (1947), put forward subsequently, addressed a network of Gaussian chains free of all interactions with one another, the integrity of the chains which precludes one from the space occupied by another being deliberately left out of account. Hypothetical networks of this kind came to be known later as phantom networks (Flory, 1964,... 

The first dye laser generates 10-ps, 2-pJ, 365-nm pulses that pump a microscopic distributed feedback dye laser (DFDL) producing Fourier transform hmited 0.7-ps pulses at 616 nm. These DFDL pulses are amplified in two stages to give 100-pJ, diffraction-limited pulses. 

Fakan, S., Leduc, Y., Lamarre, D., Brunet, G. and Poirier, G.G. (1988) Immunoelectron microscopical distribution of poly(ADP-ribose)polymerase in the mammalian cell nucleus. Exp. Cell Res., 179, 517-526. 

Laser microprobe mass analyzers permit mass spectrometric analysis of very small volumes (0.01-1 pm3) of thin Sections. The method is based on laser induced ion production from a microvolume and analysis of the evaporated ions in a time-of-flight mass-spectrometer. The technique allows detection of all elements and isotopes with a sensitivity approaching the ppm range and an extremely low limit of detection 10 15 to 10-20 g. Transmission type instruments such as the LAMMA 500 are designed for the analysis of particles of 3 pm in diam. The lateral resolution is about 0.5-1 pm. Because the area to be analyzed is selected by an optical microscope, distribution of chemical constituents can be precisely correlated with morphologic structures (Hillenkamp et al., 1982 39), Simons, 198440), Kaufmann, 1984)41 >. 

Recently, ferroelectric materials, especially in thin film form, have attracted the attention of many researchers. Their large dielectric constants make them suitable as dielectric layers of microcapacitors in microelectronics. They are also investigated for application in nonvolatile memory using the switchable dielectric polarization of ferroelectric material. To characterize such ferroelectric materials, a high-resolution tool is required for observing the microscopic distribution of remanent (or spontaneous) polarization of ferroelectric materials. 

Petralia RS, Yokotani N, Wenthold RJ. 1994b. Light and electron microscope distribution of the NMDA receptor subunit NMDARl in the rat nervous system using a selective anti-peptide antibody. J Neurosci 14 667-696. 

Fig. 34a), the li/r l distributions are strongly peaked near i/rg = l, indicative of a high degree of local triangular order. As the system melts (Fig. 34b), the distributions develop a tail at small values of i/r l. As we have seen for other microscopic distribution functions, the distributions display an isosbestic point in the coexistence region (Fig. 34b), at =0.9, consistent with the behavior expected for solid-liquid coexistence. 

Jaarsma D, Levey AI, Frostholm A, Rotter A, Voogd J (1995a) Light-microscopic distribution and parasagittal organisation of muscarinic receptors in rabbit cerebellar cortex. J. Chem. Neuroanat., 9, 241-259. 

Mixing due to the microscopic distribution of pore water velocities, known as hydrodynamic dispersion, is illustrated in Fig. 3-2. Figure 3-2A shows the pore water velocity profile, v(y) for Poiseuille flow in a uniform capillary tube of radius r. Additional spreading can occur due to the irregular shape of natural pores as compared to ideal cylinders (Fig. 3-2B). 

Deposit thickness distribution in wafer electroplating must be considered in terms of two separate scales. (1) Macroscopic distribution, on the wafer scale (cm) and (2) microscopic distribution, on the length scale of the features (microns). Because of the large variation (4-5 orders of magnitude) between the scales, these distributions are controlled by different mechanisms. Furthermore, the design objectives for the two scales are quite different. While it is important to obtain uniform deposit thickness on the wafer scale, a bottom-up fill is desired on the features scale, since uniform deposition leads to the formation a center seam. 

The uniform chemical environment of a CSTR makes it ideally suited for the production of copolymers. If the assumption of perfect mixing is justified, there will be no macroscopic composition distribution due to monomer drift, but the mixing time must remain short upon scaleup. See Sections 1.5 and 4.4. A real stirred tank or loop reactor will more closely approach perfect mixing when the circulation rate is high. The narrowing of the macroscopic composition distribution as a function of circulation rate can be modeled. When the macroscopic distribution becomes commensurate in breadth to the microscopic distribution, further inputs of power are unwarranted. 

This mass spectrometric method for trace analysis is mainly used in multi-element analysis of surfaces and thin films. Also, microscopic distributions of elements in depth concentration profiles and in adsorption processes are determined - . A stable ion bombardment by a primary beam of a few kV is capable of ionizing atoms and molecules from the surface of a solid sample (about 100 A deep). 

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