Masking index

A masking index is defined by —logaM" " [Equation (11-13), where M includes the free metal ions, the various hydroxy complexes, and also ML, MLj,... from reactions of the metal ion with masking ligands]. The masking index can be calculated from the same type of data used to derive Figure 11-4. 

FIGURE 11-10 Masking index as a function of pH for aluminum in 0.1 M fluoride. From Perrin, p. 27.)... 

Assume that log P4, for chloride, bromide, and iodide with Zn is — 1, — 0.74, and — 1.25 and with Cd" " is 0.9, 2.53, and 6.1. (a) Calculate the masking index for Zn" " and Cd" " in 1.0 Af chloride, 1.0 Af bromide, and 0.1 Af and 1.0 Af iodide. Assume activity coefficients of unity and that the metal ions are present predominately as their highest complexes, (b) Assuming that the conditional formation constants of Zn" " and Cd with EDTA are the same (Figure 11-3), which condition is most favorable for the titration of zinc in the presence of cadmium ... 

A solution of 0.001 Af iron(lll) is masked by the addition of 0.05 Af EDTA. (a) Calculate the masking index at pH 2, assuming formation of hydroxy complexes is negligible, (b) Calculate the masking index for aluminum(III) under the same conditions. 

The schlieren microscope is able to detect refractive index variations to six decimal places. Any small difference in optical path (index difference, film thickness, etc) is very precisely detected by the schlieren microscope, especially in the Dodd modification. It is, in effect, a darkfield method. The specimen is illuminated with light in a portion of the illuminating cone and that direct light is masked in the conjugate back focal plane of the objective (Fig. 3). The only light to pass through this plane is refracted, reflected, or diffracted by the specimen. 

The procedure utilises eriochrome blue black RC (also called pontachrome blue black R Colour Index No. 15705) at a pH of 4,8 in a buffer solution. Beryllium gives no fluorescence and does not interfere iron, chromium, copper, nickel, and cobalt mask the fluorescence fluoride must be removed if present. The method may be adapted for the determination of aluminium in steel. 

IDLH (immediately dangerous to life and health) is an index of exposure used in the United States. If such a concentration is reached, there is a need for emergency evacuation of buildings or use of an insulating mask. 

In flame retarding nonwovens, the contribution of components may not be additive. Rather, the interaction of binder, flame retardant, and substrate is critical in the performance of the flame retardant nonwoven. Similarly, the flammability of a binder film or the flammability of a flame retardant coated woven cloth often do not predict the flame retardancy of the same binder or flame retardant on a nonwoven substrate of rayon or polyester. Actual data on a nonwovens substrate is the only accurate measure of a system s flame retardancy. For this study, two widely used substrates were selected. The first, lightweight rando rayon, is representative of material used in nurse caps, surgeon s masks, and miscellaneous coverstock. This material is constructed of 1 1/2 denier fiber, weighs 1 1/2 ounces per square yard, and is relatively dense web. Rayon as a material is water absorbent, burns rather than melts, and is readily flammable. This fiber ignites around 400°C(2) and has an oxygen index of about 19.0. Certain binders adhere well to rayon while others do not. Apparently, this lack of affinity for the substrate affects flame retardancy, as will be demonstrated later. 

Figure 47, SAMPLE generated profile simulations in AZ1350J resist exposed at 436 nm on an index matched substrate. The mask edge is at 0.75um on the horizontal scale. The unbleachable optical absorbance (A) was varied from the actual value at 436 nm, 0.08 to 0.43. The dose was adjusted to develop each case to dimension (l.5um space) at constant development time. As A increases, all other factors being constant, the dose required to open the line increases and the resist profile becomes...

In equation 1, bmin is the minimum feature size transferable, A is the wavelength of light, s is the separation between the mask and the substrate, and d is the thickness of the resist layer. In projection printing, a series of undulating maxima and minima are produced. Because of mutual interference, the dark region is never completely dark, and the maximum brightness does not correspond to 100% transmission. The quality of transfer can be conveniently indicated by the modulation index, M, which is defined as follows ... 

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