Shape distribution, physical

In addition to size, shape, distribution, and volume fraction of structural elements generated by proteins, physical and chemical interactions among proteins and other food ingredients also play significant roles in determining the sensory attributes such as texture, flavor, and taste stability satiety and bioactivity of foods (Aguilera and Stanley, 1999 Parada and Aguilera, 2007 Lundin et al., 2008 McClements et al.,... 

The excitation of the surface plasmon is found to be an extinction maximum or transmission minimum. The spectral position v half-width (full width at half-maximum) T and relative intensity f depend on various physical parameters. First, the dielectric functions of the metal and of the polymer Cpo(v) are involved. Second, the particle size and shape distribution play an important role. Third, the interfaces between particles and the surrounding medium, the particle-particle interactions, and the distribution of the particles inside the insulating material have to be considered. For a description of the optical plasmon resonance of an insulating material with embedded particles, a detailed knowledge of the material constants of insulating host and of the nanoparticles... 

The sharpness of the transition region in the curves is determined by the channel-size distribution. The overall shape of the curves is due to treating the surface energies and interactions in terms of capillary phenomena. This shape makes physical sense in that the transition between the two types of transport modes should be relatively sharp for this kind of phase-transition... 

There is a demand for rational methods for the development of new catalysts. Strong efforts in this direction have led to a deeper insight into catalytic phenomena on a molecular level. A key design consideration in catalysis is the optimum pore structure of catalyst particles. Design parameters may be distribution of pore radii, distribution of pore length, pore shape, distribution of catalyst crystallites (active centers) within the pores or connectivity. The variable design parameters are constrained between upper and lower bounds due to physical limitations. 

The properties of fillers such as geometric shape, particle size and distribution, physical and chemical properties, and so on will directly affect the material performances of the filling modification system. Fillers are classified mainly into the following kinds. 

To distinguish between colloid stability/instability and physical stability one must consider the state of the suspension on standing as schematically illustrated in Fig. 3.39. These states are determined by (i) magnitude and balance of the various interaction forces, electrostatic repulsion, steric repulsion and van der Waals attraction (ii) particle size and shape distribution (iii) density difference between... 

Equation (7) is an ill-conditioned Laplace transform. As such it is known that no unique solution exists. A number of formally different distribution shapes, including physically unreasonable ones, will fit the measured ACF within experimental error. This is a fundamentally limiting feature of PCS. And it is the primary reason why PCS does not produce, reliably, well resolved size distributions, except for computer simulations. 

Many physical and chemical factors affect the fraction of rapid and slow dissolution and the dissolution rate constants. These include the chemical composition of the actinide and the solvent, the particle size and shape distribution, particle roughness, adsorbed molecules, crystallinity, hydration state, porosity, density and process history. Equation 1 quantifies the dissolution rate for particles in terms of surface area where M/Mo = imdissolved mass fraction k = dissolution rate constant (g m d ) S = specific surface area (m g" ) and t = time (d). ... 

The physical significance of the zeta potential is discussed in the following section. The suspension could be characterised by particle charge density, which can in principle be determined from the electrophoretic mobility, but which requires certain assumptions regarding the particle size and shape distribution and conductivity effects. The zeta potential is the most commonly used parameter for characterising a suspension, and can be determined from measurements of particle velocity or mobility in an applied field using commercially available electrophoresis cells. In practice electrophoretic mobilities are not easy to measure accurately, and since the Smoluchowski equation is based on a model of doubtful validity, the view sometimes expressed that "zeta potentials are difficult to measure and impossible to interpret" has a ring of truth but is probably unduly pessimistic. The Smoluchowski relation is valid provided that the double... 

The value of pigments results from their physical—optical properties. These ate primarily deterrniaed by the pigments physical characteristics (crystal stmcture, particle size and distribution, particle shape, agglomeration, etc) and chemical properties (chemical composition, purity, stabiUty, etc). The two most important physical—optical assets of pigments are the abiUty to color the environment in which they ate dispersed and to make it opaque. 

The most commonly measured pigment properties ate elemental analysis, impurity content, crystal stmcture, particle size and shape, particle size distribution, density, and surface area. These parameters are measured so that pigments producers can better control production, and set up meaningful physical and chemical pigments specifications. Measurements of these properties ate not specific only to pigments. The techniques appHed are commonly used to characterize powders and soHd materials and the measutiag methods have been standardized ia various iadustries. 

Important physical properties of catalysts include the particle size and shape, surface area, pore volume, pore size distribution, and strength to resist cmshing and abrasion. Measurements of catalyst physical properties (43) are routine and often automated. Pores with diameters <2.0 nm are called micropores those with diameters between 2.0 and 5.0 nm are called mesopores and those with diameters >5.0 nm are called macropores. Pore volumes and pore size distributions are measured by mercury penetration and by N2 adsorption. Mercury is forced into the pores under pressure entry into a pore is opposed by surface tension. For example, a pressure of about 71 MPa (700 atm) is required to fill a pore with a diameter of 10 nm. The amount of uptake as a function of pressure determines the pore size distribution of the larger pores (44). In complementary experiments, the sizes of the smallest pores (those 1 to 20 nm in diameter) are deterrnined by measurements characterizing desorption of N2 from the catalyst. The basis for the measurement is the capillary condensation that occurs in small pores at pressures less than the vapor pressure of the adsorbed nitrogen. The smaller the diameter of the pore, the greater the lowering of the vapor pressure of the Hquid in it. 

Transition aluminas are good catalyst supports because they are inexpensive and have good physical properties. They are mechanically stable, stable at relatively high temperatures even under hydrothermal conditions, ie, in the presence of steam, and easily formed in processes such as extmsion into shapes that have good physical strength such as cylinders. Transition aluminas can be prepared with a wide range of surface areas, pore volumes, and pore size distributions. 

Characterization. The proper characterization of coUoids depends on the purposes for which the information is sought because the total description would be an enormous task (27). The foUowiag physical traits are among those to be considered size, shape, and morphology of the primary particles surface area number and size distribution of pores degree of crystallinity and polycrystaUinity defect concentration nature of internal and surface stresses and state of agglomeration (27). Chemical and phase composition are needed for complete characterization, including data on the purity of the bulk phase and the nature and quaHty of adsorbed surface films or impurities. 

The physics and modeling of turbulent flows are affected by combustion through the production of density variations, buoyancy effects, dilation due to heat release, molecular transport, and instabiUty (1,2,3,5,8). Consequently, the conservation equations need to be modified to take these effects into account. This modification is achieved by the use of statistical quantities in the conservation equations. For example, because of the variations and fluctuations in the density that occur in turbulent combustion flows, density weighted mean values, or Favre mean values, are used for velocity components, mass fractions, enthalpy, and temperature. The turbulent diffusion flame can also be treated in terms of a probabiUty distribution function (pdf), the shape of which is assumed to be known a priori (1). 

The powders of zeolites of various trademarks are used to produce petroleum-refining catalysts. In this connection, it is very important to have complete information concerning not only chemical composition and distribution of impurity elements, but also shape, surface, stmcture and sizes of particles. It allows a more detailed analysis of the physical-chemical characteristics of catalysts, affecting their activity at different stages of technological process. One prospective for solving these tasks is X-ray microanalysis with an electron probe (EPMA). 

Engineering factors include (a) contaminant characteristics such as physical and chemical properties - concentration, particulate shape, size distribution, chemical reactivity, corrosivity, abrasiveness, and toxicity (b) gas stream characteristics such as volume flow rate, dust loading, temperature, pressure, humidity, composition, viscosity, density, reactivity, combustibility, corrosivity, and toxicity and (c) design and performance characteristics of the control system such as pressure drop, reliability, dependability, compliance with utility and maintenance requirements, and temperature limitations, as well as size, weight, and fractional efficiency curves for particulates and mass transfer or contaminant destruction capability for gases or vapors. 

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