Appearance defects

In some cases samples are processed on a laboratory version of the production unit and the tests may be more concerned with materials quality than with processability. However, processability can become an issue when a masterbatch or compound introduces problems of achieving uniform coloring or specified electrical properties, etc. In extrusion, agglomerates can produce surface appearance defects, obstructions in small bore tubing (following "die drool"), voltage breakdown in cables, and failure to meet dispersion requirements of pipe, cable, and cistern standards. 

The most common processing issues in working with polycarbonate-based resins are appearance defects. The most common type of aesthetic defect is the appearance of contaminant inclusions within transparent parts, commonly known as hlack specks. These defects are usually found to be degraded resin—either within the polycarbonate stream or from other resin sources—and occur when charred material, which has formed over time on the surface of the processing equipment, breaks away and... 

Scrap may also be extrusions with dimensional or appearance defects which can be reused blended with virgin polymer at an agreed ratio. Providing various housekeeping and quality issues are met, there should be no mixing difficulties, but there are instances where a separate extrusion line processing 100% scrap with suitable screw mixing facilities is necessary. 

This vitamin was discovered by Kdgl in 1934 and later identified with Gydi s vitamin P M5). The protein-bound form of this vitamin can be liberated by a peptidase lJi6). The metabolic events which appeared defective in biotin deficiency are associated with the fixation of COt in various biosynthetic processe6 H7-149). A more specific chemical participation of botin in CO fixation was formulated recently by L3men ef al. ISO) who studied the mechanism of the enzymic carboxylation of fj-hydroxyisovaleryl CoA. The over-all process is as follows ... 

Weld lines are common defects often found on the exterior surfaces of plastic injection molding parts. Weld lines are not only appearance defects, they also decrease the mechanical strength of the parts. [1,2,3]... 

The case of thin-skin regime appears in various industrial sectors such as aerospace (with aluminium parts) and also nuclear in tubes (with ferromagnetic parts or mild steel components). The detection of deeper defects depends of course on the choice of the frequency and the dimension of the probe. Modelling can evaluate different solutions for a type of testing in order to help to choose the best NDT system. 

If in the section defects are absent, the projections is distributed accidentally on pixels and the values of functions p(ij) aproximately are alike in all pixels of the section. In defective areas the projections are focused and, as far as defect appearance is unlikely on accepted hypothesis... 

The sensitivity to defects and other control parameters can be improved by optimizing the choice of the probe. It appears, after study of different types of probes (ferritic, wild steel, insulator) with different geometries (dish, conical,. ..), necessary to underline that the success of a feasibility research, largely depends on a suitable definition of measure collectors, so that they are adapted to the considered problem. 

Another phenomenon is so called two-side filling of one-side closed conical capillaries with liquid [5]. On the one hand the more penetrant is trapped by the defect the wider indication will appear. Contrariwise it is almost impossible to extract a penetrant from the completely filled surface defects by dry developer [6]. In this study we propose the theory of the phenomenon. Besides experimental results of the investigation of two-side filling with various penetrants of conical capillaries are presented. Practical recommendations to optimize liquid penetrant testing process are proposed. 

Experimentally, local vibrational modes associated witli a defect or impurity may appear in infra-red absorjrtion or Raman spectra. The defect centre may also give rise to new photoluminescence bands and otlier experimentally observable signature. Some defect-related energy levels may be visible by deep-level transient spectroscopy (DLTS) [23]. 

Primary immunodeficiencies are uncommon, and may occur in 1 in 10,000 individuals (6). Many primary immunodeficiencies are hereditary and congenital, and first appear in infants and children. Primary immunodeficiencies are classified into four main groups (7) relating to the lymphocytes (B-ceUs, T-ceUs, or both), phagocytes, or the complement cascade (8). Primary deficiency diseases result from B-ceU defects in 50% of cases, from T-ceU defects in ca 10%, and from combined B- and T-ceU defects in ca 20%. Phagocytic disorders account for 18% and complement defects occur in 2% of all cases. 

Cystic fibrosis, a disease of the Caucasian population, is associated with defective CL regulation and is essentially a disorder of epithehal cells (113,114). The defect arises at several levels in the CL ion transporter, ie, the cystic fibrosis transmembrane regulation (CFTR), and is associated with defective CL transport and defective processing, whereby the protein is not correctiy incorporated into the cell membrane. The most common mutation, affecting approximately 60% of patients, is termed F 608 and designates the loss of phenylalanine at this position. This mutation appears to be at least 50,000 years old, which suggests that its survival may have had evolutionary significance (115). 

Two comments sought to give content to the terms "defective condition" and "unreasonably dangerous" that appear ia this rule ... 

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