Intrinsic material properties

Transmission and reflection properties of certain materials form the basis of the oldest and simplest method of isolahng spectral intervals. If one measures the 

The importance of these materials goes beyond that of the design of broad-band transmission filters. The very same substances are also used in the constmction of interference filters, prisms, Fabry-Perot etalons, beam dividers, dichroic mirrors, and sometimes as windows to seal parts of an instrument while permitting radiation to pass. 

While glasses, natural and synthetic crystals, and semiconductors provide at least several choices for the design of optical components in the near and middle infrared, suitable bulk materials are more limited at longer wavelength. Quartz, 

At long wavelengths reflection filters can be based on the residual ray effect (Hagen Rubens, 1903). At certain frequencies the crystal lattice vibration is being excited and the crystal reflects well (Czerny, 1930 Strong, 1958). 

Conductive grids may also serve as optical filters in the far infrared (Vogel Genzel, 1964). A variety of techniques are used in their construction. Evaporated or electrochemically deposited metals on dielectric, transparent substrates (mylar, quartz) can be used, or simply a flat metal foil with patterns of small holes punched into it. Woven wire grids, such as commonly employed as sieves, can serve double duty as far infrared filters. With electroformed or vacuum deposited grids it is possible to construct two complementary versions, inductive and capacitive grid patterns (Smith et al, 1972). 

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The van der Waals and other non-covalent interactions are universally present in any adhesive bond, and the contribution of these forces is quantified in terms of two material properties, namely, the surface and interfacial energies. The surface and interfacial energies are macroscopic intrinsic material properties. The surface energy of a material, y, is the energy required to create a unit area of the surface of a material in a thermodynamically reversible manner. As per the definition of Dupre [14], the surface and interfacial properties determine the intrinsic or thermodynamic work of adhesion, W, of an interface. For two identical surfaces in contact ... 

Studies have shown that in order to clear the oropharyngeal impaction barrier (comprising the mouth, throat, and pharynx), particles with aerodynamic diameters smaller than 5 pm are required [3,4]. Only particles with aerodynamic diameters less than 3 pm reach the terminal bronchi and the alveoli in significant numbers [5]. Therefore, the particle diameter required to be produced by the delivery system depends to a great extent on the intended target lung tissue. Lung deposition is also affected substantially by the specific inhalation dynamics of the patient, which in turn are influenced by the delivery device. This article addresses various attributes of the dry powder inhalation product, from intrinsic material properties to final product performance. 

Numerical simulations produce force-deformation data whose shape and magnitude is dependent on the initial parameters defined within the model, including the elastic modulus (E), the uninflated cell radius (rQ) and the initial stretch ratio (ls). Experimental data are fitted to these numerical simulations allowing intrinsic material properties to be derived. 

Besides compression testing, AFM has been used to derive intrinsic material properties of yeast cell walls by nano-indentation. This technique was employed by Touhami et al. (2003) to determine the... 

The threshold energy needed for light absorption (i.e., the band-gap energy) and the relative positions of the band edges i.e., the flat band potential) are intrinsic material properties of each semiconductor. 

Both values are based on materials properties and are, or approximate, intrinsic materials properties. Some ideas of how an idealized HRR such as the HRRst can be deduced from experimental... 

Note again, that Table 2 contains intrinsic materials properties, representative of homogeneous bulk or thin film materials. Addition of third or fourth elements for grain decoupling or columnar growth will likely lower anisotropy and magnetization values and hence compromise the ultimately achievable areal density. 

Bad products result from the wrong choice of material, poor processing, wrong application and often poor design. What we ultimately need are methods of predicting use properties from intrinsic material properties and processing parameters. In this book attention will mainly be paid to the intrinsic material properties of polymers. 

Mesoscopic physics is the field concerned with solids so small that their intrinsic properties are no longer scale-invariant. In other words, below some critical size (in at least one dimension), intrinsic materials properties are no longer constant. 

A macroscopic property is an intrinsic materials property, which remains scale invariant (size independent) or intensive (independent of the mass of the sample). 

Also, because all three rather different apparatus give fairly similar and reproducible results, one has greater confidence that all three are measuring intrinsic materials properties with acceptable accuracy. 

The viscoelastic nature of polymers generally determines rate and temperature dependence of their mechanical properties. At low strain levels, i.e. in a linear regime, this dependence is well described by intrinsic material properties defined within constitutive viscoelastic laws [1]. At high strains, in presence of failure processes, such as yielding or fracture, it is more difficult to establish a constitutive behaviour as well as to define material properties able to intrinsically characterise the failure process and its possible viscoelastic features. 

The results of the TTF experiments are of course dependent on specimen geometry and thus do not produce an intrinsic material property. Therefore comparisons between TTF results will only be valid in experiments that use identical specimens. However, TTF experiments are shown to discriminate, to a high resolution, the ESC resistance of polymer/fluid combinations [16]. 

The concept of polymer properties includes not only the intrinsic material properties, but also the processing properties and the properties of the manufactured objects [1]. All these are of significant practical importance, and a variety of techniques are used for their characterization. The intrinsic properties refer to the polymer as a substance. The processing refers to the fabrication procedures of the manufactured objects. 

Fig. 2 shows a qualitative comparison of the stress states using a similar format to that adopted by Cundall (1990). Components of the stress inside the fault/shear band in the homogeneous sand are reduced (Fig. 2). Our model showed that this effective weakening of the material (resulting solely from reduction of confining pressure, i.e., without any need for change of intrinsic material property) continues at larger displacements. Weakening of the material in a normal fault thus appears to be a natural characteristic...

In asymmetric supported membranes the use of permeability data can give rise to much confusion and erroneous conclusions for several reasons. In most cases the layer thickness is not precisely known and usually it is not known whether this layer is homogeneous or has property gradients (e.g. a "skin" and a more porous part). In many cases the material of the layer penetrates the support to some extent and so it is not possible to separate properties of separation layer and support without giving account of the interface effect. Finally, even if all these complications can be avoided, a comparison based on separation layer properties expressed in terms of permeabilities can give a completely wrong impression of the practical possibilities (as done in e.g. Ref. [109]). This is illustrated by comparison of hydrogen permeabilities of ultra-thin silica layers (see Tables 9.14-9.16) with other materials such as zeolites and metals. The "intrinsic" material properties of these silica layers are not impressive ... 

There is also an important property of H-bonds H-bonding interactions are not dependent on intrinsic material properties and can be active between two surfaces having no H-bonds within them. Unlike van der Waals interactions, H-bonding interactions are essentially asymmetrical and can only be satisfactorily treated by taking that asymmetry into account. 

Several publications on the processing of membranes based on these materials could be found in the literature [5-28]. The selection of membrane material for a given application could be divided in to two parts Screening of materials based on bulk properties and screening based on thin film properties. In the former case, intrinsic material properties such as stability and conductivity will decide the outcome of the research work. In the latter case, the defect free formability of thin film will be the deciding part. The method of film formation as well as the quality of the support substrates could become important in this respect. In supported membranes, material stability and membrane performance are very much related. The most important issue - the application of membranes in high temperature environments - is therefore the study of the stmcture of the membrane/material and its correlation with the stability/durability. 

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