Dark specs

Many problems may be encountered in thermoforming, some of these are related to plasticizers or they can be eliminated by changes in plasticizer type and amount Problems related to plasticizers include die lines or dull spots (plate-out buildup), dark specs and streaks (polymer degradation), excessive sag, distortion after part removal, warpage, poor wall thickness distribution, and part sticking to mold. 

Even daylight will produce dark specs of Ag on thin layers of AgN03 solution. Using a low pressure mercuiy lamp and irradiating 200 cm water, in which 0.2 g silver nitrate was dissolved together with 2.0 g anatase, for 30 minutes, the darkened P25 anatase was found to have gained 0.098 g. The silver deposit is easily dissolved by hot dilute nitric acid. Thus silver can be... 

One of the most important redox reactions of this class of compounds is the oxidation of Pt(2.0+)2 by 02, for this is the main cause of the appearance of the blue, purple, or dark red colors of the mixed-valence species. Although no detailed examination has been performed, the kinetics of the 02 oxidation of I Pt,1 (NHo)4(a-pyrrolido-nato)2]2+ into I Pt1 VNH3)4(a-pyrrolidonato)2(H20)2 I41 (Eq. (7)) was spec-trophotometrically examined (117). The study showed that the reaction proceeds over several days at room temperature. The first-order rate constants in acidic media were in the range of kobs = 4.2 x KT6 s 1 (pH = 0.23) - 1.13 x lO6 s"1 (pH = 2.1) (at 25°C, in air, I = 1.5 M) (117). 

The entire body is yellow with variable dusky pattern, usually there are two longitudinal dark bands over the mesosoma and the pedipalps and legs are spotted. The pattern may be absent in some specimens or populations. This species is very distinctive. Its light, smooth and polished chitin makes it look as if it were made of crystal. Most stings occur when the scorpion is suprised, otherwise this is a very timid and flighty spec-imin. 

FIGURE 48. Representative H NMR spectra (fuU lines) of dark-adapted bR (90 mg) containing deuteriated relink, with line shape simulations (dashed lines) superimposed. Both the powder spec-tmm (a) from randomly oriented PM patches and the tilt series (b) over sample inchnations, a = 0, 45° and 90°, were recorded at —60°C (number of scans, 1.7 x 10, for a = 0°). Spectrum (c) was measured at 21 °C with a = 0° (number of scans, 3 x 10 ). Reprinted with permission from Reference 60. Copyright (1997) American Chemical Society... 

Dark-gray or black powder with metallic luster or coherent mass of silver-white color body-centered cubic structure. mp 2622° (Worthing), bp about 4825°, d 10.28. Spec heat 5.68 cal /g -atom/deg heat of fusion 6.6 kcal/g.aiom heat of vaporization 142 kcal/g-atom (Stoll, Sinke). Fairly stable at Ordinary temp oxidized to the trioxide at a red heat slowly oxidized by steam. Not attacked by water, by dil acids or by coned hydrochloric acid. Practically insol in alkali hydroxides or fused alkalies. Reacts with nitric acid, hot coned sulfuric acid, fused potassium chlorate or nitrate. Attacked by fluorine at Ordinary temp, by chlorine or bromine at a red heat. 

These observations surprised me, because if the furnace oil is dark, the Fluid Catalytic Cracking Unit (FCCU) feed cut (i.e., the next lowest product draw) must be even darker. However, when I inquired as to the color of the FCCU feed drawoff, the operators responded that this product was right on spec. That is, it was black. 

Spec determination of the iron (II)-2,2 -bipyridine dark red complex... 

Crystals of [Co(en)2(SCHjCOO)] (CIO4) are dark purple, sometimes appearing black. The perchlorate salt, which crystallizes from the reaction mixture, is soluble in HjO (1.1 X 10 M in 0.01 M HCIO4), slightly soluble in dimethyl sulfoxide (DMSO), DMF, and sulfolane, and insoluble in ethanol. The chloride salt is very soluble in water and insoluble in all other solvents listed above. The (PFe) salt is soluble in DMSO, DMF, and tetrahydrothiophene 1,1-dioxide and insoluble in ethanol. The compound is characterized by its visible-UV spec-trum, which has a peak at 518 nm (e = 152 M cm ) and a characteristic sulfur-to-metal charge-transfer band at 282 nm (e = 11,700M cm ) by which the purity of the compound can be estimated. 

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