Transparency number

It is possible to colorimetrically determine the ability of a pigmented layer to scatter light above a black substrate i.e., its transparency (Sec. 1.6.1.3) by finding the normal value Y or the distance A ab on the DIN 6174 Color Chart. This method may also be used to compare increasingly thick layers. To quantitatively describe the transparency of a system, the so-called Transparency Number / lias been introduced. It is defined as the inverse of the distance AE ah between colors... 

However, the transparency number is not only a function of pigment and vehicle it usually changes with the thickness of the layer (e.g., the pigment surface concentration). The transparency number of a sample which is applied at a thickness somewhere in the interval between two limits hi and h2 is calculated as follows ... 

Transparency. Transparency is expressed quantitatively as the transparency number. This is defined as the reciprocal of the increase in color difference AE b on a black substrate obtained on increasing the film thickness h of the pigmented medium. The transparency number has the unit mm ( = L/m2). It indicates the number of liters of pigmented medium needed to coat 1 m2 of a black substrate in order to obtain a color difference of AE%b = 1 relative to this substrate. In a simplified method the transparency number can be determined by evaluating one or two points on the straight part of the AE b(h) curve. A computer method is more exact, furthermore calculations can be made using the spectral principle of spectral evaluation (see above). For standards, see Table 1 ( Transparency ). 

D-CTViewer allows to create up to three different Isosurfaces inside the data volume with each having different color and transparency value. The number of polygons inside the Isosurface hull can be decimated using a special polygon reduction tool (Fig. 5). 

The relationship between tlie lattice gas and the Ising model is also transparent in the alternative fomuilation of the problem, in temis of the number of down spins [i] and pairs of nearest-neighbour down spins [ii]. For a given degree of site occupation [i]. 

In 1960, Harrick demonstrated that, for transparent substrates, absorption spectra of adsorbed layers could be obtained using internal reflection [42]. By cutting the sample in a specific trapezoidal shape, the IR beam can be made to enter tlirough one end, bounce internally a number of times from the flat parallel edges, and exit the other end without any losses, leading to high adsorption coeflScients for the species adsorbed on the external surfaces of the plate (Irigher than in the case of external reflection) [24]. This is the basis for the ATR teclmique. 

Finally, semi-classical approaches to non-adiabatic dynamics have also been fomuilated and siiccessfLilly applied [167. 181]. In an especially transparent version of these approaches [167], one employs a mathematical trick which converts the non-adiabatic surfaces to a set of coupled oscillators the number of oscillators is the same as the number of electronic states. This mediod is also quite accurate, except drat the number of required trajectories grows with time, as in any semi-classical approach. 

Polyaniline (PANI) can be formed by electrochemical oxidation of aniline in aqueous acid, or by polymerization of aniline using an aqueous solution of ammonium thiosulfate and hydrochloric acid. This polymer is finding increasing use as a "transparent electrode" in semiconducting devices. To improve processibiHty, a large number of substituted polyanilines have been prepared. The sulfonated form of PANI is water soluble, and can be prepared by treatment of PANI with fuming sulfuric acid (31). A variety of other soluble substituted AJ-alkylsulfonic acid self-doped derivatives have been synthesized that possess moderate conductivity and allow facile preparation of spincoated thin films (32). 

Beckman Elutriation Method. The Beckman elutriation method uses a chamber designed so that the centrifugal effect of the radial inward fluid flow is constant (Fig. 3). The separation chambers are made of transparent epoxy resin which faciUtates observation of the movements of the cell boundary in strobe light illumination. This enables detection of the radius at which the cells are separating. When a mixture of cells, eg, mononuclear white cells, enters the chamber, separation can be achieved by fine tuning centrifuge speed and inward fluid flow to the specific cell group. This is a laboratory method suitable for relatively small numbers of cells. Chambers are available in sizes to handle 2-3 x 10 , 1 2 x 10 , and 1 x 10 ° cells. The Beckman chambers can be appHed to collect mononuclear cells from bone marrow aspirates. 

Chemical Durability. The resistance of nontransparent vitreous sihca to chemical attack is slightly less than the resistance of transparent vitreous sihca. This difference results primarily from the higher surface area of the former caused by the presence of a large number of bubbles. Most data in the hterature are on the transparent material. 

When doped, low band-gap polymers have optical transitions in the infrared region of the spectmm, and therefore transmit more visible light in the conducting form than in the insulating form. This feature enables this class of conducting polymers to be investigated for a number of optical appHcations where both electrical conductivity and optical transparency are desired. 

There are a number of occasions where a transparent plastics material which can be used at temperatures of up to 150°C is required and in spite of its relatively high cost, low impact strength and poor aging properties poly-(4-methylpent-1 -ene) is often the answer. Like poly(vinyl chloride) and polypropylene, P4MP1 is useless without stabilisation and as with the other two materials it may be expected that continuous improvement in stabilising antioxidant systems can be expected. 

---