Weak transparency

Weak transparency It is difficult (but not impossible) to attend directly to our experience that is, we can most easily attend to our experience by attending to the objects represented by that experience. 

Weak transparency It is difficult to be aware of the intrinsic features of our experiences. We are almost always instead aware of the intrinsic features of the objects of our experiences. 

Kind notes that Thomas Reid was an early proponent of weak transparency. He compares sensations to the words of a language, wherein we do not attend to the sound, but to the sense. And he repeatedly has occasion to say things like this ... 

The anulsion polymers are either used directly as a latex or dried for use in coatings or melt processing. Polyvinylidene chloride itself is a weak, transparent, pliable thermoplastic however, the polymer crystallizes with aging and becomes stronger and more opaque. 

No change compared to reference sample Traces of yellow or red-brown coloration Light yellow,- orange, -brown Dark brown, weak transparency Deep brown, black, almost opaque... 

There are complicating issues in defmmg pseudopotentials, e.g. the pseudopotential in equation Al.3.78 is state dependent, orbitally dependent and the energy and spatial separations between valence and core electrons are sometimes not transparent. These are not insunnoimtable issues. The state dependence is usually weak and can be ignored. The orbital dependence requires different potentials for different angular momentum components. This can be incorporated via non-local operators. The distinction between valence and core states can be addressed by incorporating the core level in question as part of the valence shell. For... 

As already discussed, transparent specimens are generally only weakly visible by their outlines and flat areas caimot be distinguished from the surroundings due to lack of contrast. In addition to the phase contrast teclmiques, light interference can be used to obtain contrast [8, 9]. 

Optical detectors can routinely measure only intensities (proportional to the square of the electric field), whether of optical pulses, CW beams or quasi-CW beams the latter signifying conditions where the pulse train has an interval between pulses which is much shorter than the response time of the detector. It is clear that experiments must be designed in such a way that pump-induced changes in the sample cause changes in the intensify of the probe pulse or beam. It may happen, for example, that the absorjDtion coefficient of the sample is affected by the pump pulse. In other words, due to the pump pulse the transparency of the sample becomes larger or smaller compared with the unperturbed sample. Let us stress that even when the optical density (OD) of the sample is large, let us say OD 1, and the pump-induced change is relatively weak, say 10 , it is the latter that carries positive infonnation. 

The spectra of saturated heterocycles are generally fairly featureless, with amine n —>a absorptions and those transitions associated with sulfur showing up weakly, while saturated ethers are usually transparent down to 210 nm. 

Methylpentene polymer, a light plastic, has a crystalline melting point of 464 retention up to 392° F, transparency of 92%, and electrical properties similar to fluoroethylene. Its impact strength is greater than polystyrene and polymethyl methacr resistant to alkalies, weak acids, and non-chlorinated solvents. It may be injection m< implements for food packaging and preparation, medical care, and non-stick coating ... 

Orthoboric acid, B(OH)3, is the normal end product of hydrolysis of most boron compounds and is usually made ( 160 000 tonnes pa) by acidification of aqueous solutions of borax. Price depends on quality, being 805 per tonne for technical grade and about twice that for refined material (1990). It forms flaky, white, transparent crystals in which a planar array of BO3 units is joined by unsymmetrical H bonds as shown in Fig. 6.25. In contrast to the short O—H O distance of 272 pm within the plane, the distance between consecutive layers in the ciystal is 318 pm, thus accounting for the pronounced basal cleavage of the waxy, plate-like ciystals, and their low density (1.48 g cm ). B(OH)3 is a very weak monobasic acid and acts exclusively by hydroxyl-ion acceptance rather than proton donation ... 

More interesting is the use of nonpolar solvents (e. g. xylene, toluene, carbon tetrachloride, hydrocarbons), because these are transparent to MW and absorb them only weakly. They therefore enable specific absorption by the reactants. If these reactants are polar, energy transfer occurs from the reactants to the solvent and the results might be different under the action of MW and A. This effect seems to be clearly dependent on the reaction and is, therefore, the subject of controversy. In xylene under reflux, for example, no MW-specific effects were observed for the Diels-Alder reaction [5] whereas important specific effects were described for aryldiazepinone synthesis [33]. 

It must be stressed that a liquid component can be substituted with an efficient absorber of microwave irradiation together with a low-melting component. The use of most typical PTC solvents (nonpolar aromatic or aliphatic hydrocarbons, or highly chlorinated hydrocarbons) is most interesting for microwave activation, because such solvents are transparent or absorb microwaves only weakly. They can, therefore, enable specific absorption of microwave irradiation by the reagents, and the results or product distributions might be different under microwave and conventional conditions [7]. 

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