Speck, black

Fig. 3. Cross-section photomicrograph of a color-negative product showing the film base, the emulsion layer (the black specks are microcrystalline silver hahde grains), and a protective overcoat. The emulsion layer and overcoat are - 3.5 x 10 m thick.

Sediment. Sediment is most commonly used as an operational check of filter efficiency and leakage, although some customers, especially those who iatend to melt the sugar iato clear solutions, write sediment restrictions. The measurement is normally done by passiag the 50% solution used for the color determination through a half black—half white filter pad and visually counting the white and black specks. 

Enamel Defects. Characterization of defects in porcelain enamel surfaces frequently requites detailed examination via microscopy to determine the sources of the defects. Defects ate divided into processing and material defects. The greatest number of defects result from processing bhsters, pinholes, black specks, dimples, tool marks, and chipping. Defects often occur from unobserved sources at almost every stage of the enameling process, but they ate not recognizable until the ware is fired. Conscientious process control helps to minimize the incidents of unacceptable finishes. 

Some telluride compounds, such as K2Te, are available commercially, however, black specks and/or a deep purple color (dependent on the pH of the solution) are frequently observed when they are dissolved in the presence of traces of oxygen. The black specks are elemental Te, while the purple color has been attributed to Te2 ions [305]. The apparent lack of stability of such solutions makes them undesirable for use in an ECALE cycle. The equilibrium shown in Eq. (5) can still be used to form Te atomic layers, however, the deposition is generally run as a stripping experiment. A small amount of bulk Te is first formed from a solution of HTe02, which is more tractable ... 

PC Loss of molecular weight by hydrolysis with water contamination, black specks... 

PPO/HIPS Blend Black specks from oxidation and styrene monomer... 

The origin of defects causing discoloration in polyolefin pellets can be identified using light and electron microscopy. For example, PE pellets from an in-plant recycle re-pelletlzing process contained pellets that were off color and had black specks, as shown In Fig. 11.6(a). One of these defects was isolated using the cross sectioning technique, as shown in Fig. 11.6(b). The cross section revealed an intense reddish particle that caused the discoloration of the pellet. 

A 60 durometer EPDM rubber for a pure bleach will not produce black speck contamination. It has the same excellent bleach and water resistance with the added feature of having food grade FDA compliance. All linings are to be designed for minimal shrinkage in cure and should have good thermal flexibility. 

Soluble substances, when brought into solution, may show slight physical impurities, such as fragments of filter paper, fibers, and dust particles. Unless excluded by definite tests or other requirements however, significant amounts of black specks, metallic chips, glass fragments, or other insoluble matter are not permitted. 

PVC-P materials, such as flooring and roofing material, can be prone to microbiological attack in humid or damp conditions. This is due to the fungi using the plasticiser at the surface of the article as a food source. This can lead to partial discolouration (pink colour or black specks) which can further cause a tacky surface where dirt can accumulate. Unpleasant odours may also be a consequence. 

Next we pour some iron filings and some powdered sulfur into a large test tube and stir them together. The sample appears to be a dirty yellow, but if we look closely, we can see yellow specks and black specks. If we hold a magnet next to the test tube (Figure 1.3c), the black particles (with some yellow particles clinging to them) are attracted by the magnet. When we pour some carbon disulfide on the sample, the liquid turns yellow. We pour off that liquid and pour on more carbon disulfide until no yellow solid remains in the sample. When we evaporate the carbon disulfide in a fume hood, we get a... 

While the primary antioxidant serves a critical role, it cannot stop all polymer peroxy radicals from propagating. This is where a second class of antioxidants, called peroxide decomposers, comes in. These molecules catalyze the decomposition of the peroxides to nonradical species, thus breaking the repetitive cycle of radical formation. Phosphites and thioesters commonly serve as secondary antioxidants. Phosphites are commonly used in HIPS resins, but care must be taken to use hydrolysis-resistant molecules to avoid the degradation of these species into black specks that render the final product unacceptable. Phosphites are usually found at levels between 500 and 2000 ppm. 

Titanium dioxide is a hard, abrasive material. Coating suspensions containing titanium dioxide have been reported to cause abrasion and wear of a steel-coated pan surface, which led to white tablets being contaminated with black specks. If titanium dioxide is used as a pigment it should conform to the appropriate food standards specifications, which are more demanding than the pharmacopeial specifications. 

In addition to problems outlined in the cabbage entry, a combination of cold injury and viral disease can cause leaves with black specks. Destroy infected plants. Caterpillars will bore small holes into sprouts see Leaves with large, ragged holes on page 56 for more details and controls. Plants deficient in potassium have poorly developed sprouts Spray with seaweed extract at transplanting and repeat several times to prevent problems. Check potassium levels with a soil test, and amend as necessary. 

Cause Black rot. Fruit shrivels into hard, black mummies reddish brown spots with black specks on leaves. 

Leaves with reddish brown spots with black specks. Cause Black rot. Leaves may wilt and shoots may show large, black, elliptical lesions. For more information, see Fruit with light brown spots that enlarge and darken above. 

Live and dead lice (about 3 mm long and greyish-white or brown in colour) and yellowish cast exoskeleton shells can be seen by combing the hair with a fine-tooth comb over a sheet of white paper, after shampooing and towelling dry. Lice faecal material (black specks) may be found on pillows and collars. 

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