Fibrous particles

The method used for grinding pressed cakes depends upon the nature of the cake, its purity, residual oil, and moisture content. If the whole cake is to be pulverized without removal of fibrous particles, it may be ground in a hammer mill with or without air classification. A 15-kW (20-hp) hammer mill with an air classifier, grinding pressed cake, had a capacity of 136 kg/h (300 Ib/h), 90 percent through No. 200 sieve a 15-kW (20-lm) screen-hammer mill grinding to 0.16-cm (Vi6-in) screen producea 453 kg/h (1000 Ib/h). In many cases the hammer mill is used merely as a preliminaiy disintegrator, followed by an attrition mill. Typical performance of the attrition mill is given in Table 20-25. A finer product may be obtained in a hammer mill in closed circuit with an external screen or classifier. 

Mechanical interlocking of particles may occur during the agitation or compression of, for example, fibrous particles, but it is probably only a minor contributor to agglomerate strength in most cases. 

Simply put, paper is manufactured by applying a watery suspension of cellulose fibers to a screen that allows the water to drain and leaves the fibrous particles behind in a web. Most modem paper products contain nonfibrous additives, but otherwise they fall within this general definition. Only a few paper products for specialized uses are created without the use of water, using dry forming techniques. The production of pulp is the major source of environmental impacts from the pulp and paper industry. 

The first sensor proposed for detecting gastric and oesophageal pH24, made use of two fluorophores, fluorescein and eosin, immobilised onto fibrous particles of amino-ethyl cellulose, fixed on polyester foils. Only tested in vitro, the sensor reveals a satisfactory response time of around 20 seconds. 

The inherent toxicity of the particle will depend on its chemical composition. For example, a particle of CdCl2 can be expected to be more toxic than NaCl because of the known toxicity of Cd+2 (6). In the case of fibrous particles, the toxicity of the material will also depend on the size and shape of the fibers, with long, thin fibers being the most toxic (7.8). 

Conversely, flocculation implies those aggregation processes effected by the intertwining of fibrous particles, for example in the wool trade, or the entrapment of silt particles in foul water, as above. 

If a fiber is less than a few micrometers thick, mineralogists may emphasize its fineness with the term fine-fibrous. Particles with diameters of a few mils (1 mil = 25 micrometers see Table 1.1) must be examined under a microscope. Electron microscopy is employed for the finest materials, and high-resolution electron microscopy is required to image fibrils with diameters of a few angstroms (1 angstrom = 10 ° meter or 0.1 of a nanometer). At any resolution, the aspect ratio can be estimated or measured as part of the identification of the fiber. 

The aerodynamic behavior of a fibrous particle is neither simple nor well understood (Timbrell, 1965). However, once any fibrous particle is suspended in ambient air, there is always the opportunity for inhalation. Fibrous particulate aerodynamics may be related, as a first approximation, to fiber diameter (Timbrell, 1979). 

The size of the fibrous particles that appear to induce disease in the animal models is compatible with the measured respiratory range in humans (Lipp-man, 1977). Most particulate deposition takes place not in the upper or conducting portion of the airways but in the alveolar region of the pulmonary tree (the respiratory unit). Some surface deposition may occur at bifurcations in the bronchial tree, but the actual amount at each location is influenced by anatomy, specific to the species—probably to an individual—as well as the variety of fiber. A large proportion of airborne particulates are rejected as part of the normal clearance mechanisms in animals, but in humans clearance mechanisms may be compromised by smoking, for example. We are unaware of any experiments on fiber toxicity using smoking rats ... 

The effects of toxins are, generally, proportional to dosage. Well-controlled dosage, as in these cell systems, provides the best opportunity for relating carcinogenicity to levels of exposure. In live animal experiments, the amount administered is usually defined as the exposure. However, not all fibrous particles will ultimately reach a specific target tissue. Measurement of the fiber load at the tissue site and the pathologic response are tedious but necessary procedures to evaluate this aspect of the problem. 

Combined chronic toxicity/carcinogenicity testing of respirable fibrous particles (July 2001)... 

Purification.—The several filtratjons and depositions above alluded to being effected, the milky liquor is allowed to flow into large settlerB, where it is loft to repose for several hours, till the whole matter in suspension falls to the bottom the clear water Is then siphoned off, and the brownish layer on the surface, consisting of fibrous particles, pulp, and other substances lighter than the fecula, scraped off as clean as... 

Another slow-burning mixt is the so-called Coal Powder. Its compn is K nitrate 70.0+1.0, oal 14.0+1.0 sulfur 16.0 1.0%. The US Armed Forces requirements for this powder are given in Spec X-PA-PD-623(listed as Type II Powder, Black, Slow Burning) which superseded Spec JAN-P-540. The coal used for this powder must be semibituminous and of such fineness that 100% passes through No 140 US Std sieve and not less than 45% through No 200 sieve. Other requirements for coal are moist 0.75%(max), ash 11.0 1.5, volatile matter 18.0 1, fixed carbon 70.5 3.5 sulfur 3.0 0.5% no foreign matter, such as gritty or fibrous particles, shall be present. 

Following are the definitions of the above terms Common banded is the common variety of bituminous and subbituminous coals it consists of a sequence of irregularly alternating layers of lenses of a homogeneous blk material having a brilliant vitreous luster a grayish-blk less brilliant striated material usually of silky luster and thin bands or lenses of soft powder and fibrous particles, known as (usain or mineral charcoal. The difference in luster of the bands is greater... 

Triethanolamine has some effect on the morphology of hydrating C3S gels [18] where it seems that the size of the fibrous particles at 2 months is greater in the presence of TEA. 

Extenders have two very broad classifications inorganic and organic. Inorganic extenders are primarily naturally occurring minerals, and these are often used in epoxy formulations. Organic extenders are naturally occurring resins or fibrous particles. In either case, the most distinguishing features of these extenders are their low cost and availability. 

The use of asbestos is being curbed because it has been shown to cause lung cancer if inhaled. A simple explanation for this is that the straight molecules in asbestos cleave easily. The asbestos dust consists of small sized fibrous particles... 

PROP Fine white fibrous particles from treatment of bleached cellulose from wood or cotton. Insol in water and most org solvs. SYNS ABICEL n P-AMYLOSE ARBOCEL ARBOCEL BC 200 ARBOCELL B 600/30 AVICEL AVICEL 101 AVICEL 102 AVICEL PH 101 AVICEL PH 105 CELLEX MX a-CELLULOSE CELLULOSE 248 CELLULOSE (ACGIH.OSHA) CELLULOSE CRYSTALLINE CELUFI CEPO CEPO CFM CEPO S 20 CEPO S 40 CHROMEDIA CC 31 ... 

Tsuda A, Stringer BK, Mijailovich SM, et al. 1999. Alveolar cell stretching in the presence of fibrous particles induces interleukin-8 responses. Am J Respir Cell Mol Biol 21 455-462. 

Vu V, Barrett JC, Roycroft J, et al. 1996. Chronic inhalation toxicity and carcinogenicity testing of respirable fibrous particles. Regul Toxicol Pharmacol 24 202-212. 

Schmidt et. al. [153] investigated the use of dark field microscopy (DFM) to measure fibrous particles. Large areas were examined for statistical reliability. A high correlation was found between DFM and light microscopy for fiber lengths greater than 1 pm. 

Both particles and toxic compounds that may contaminate a wound will be responsible for disrupting the healing pattern. The incorporation of fibrous particles into a wound may result in a granuloma that could subsequently reduce the wound strength and induce keloid scarring. It is well documented that particulate contamination can also reduce the infection resistance levels by a factor of 1.0 x 10 . 

Mechanical interlocking—fracture and deformation due to pressure that produces shape related bonding or intertwining of long fibrous particles. 

Inhalation of certain durable natural mineral fibers of amphibole asbestos, such as amosite and crocido-lite, can lead to the development of inflammation, fibroproliferation, pulmonary neoplasms, and cancer of the serosal lining of the body cavities or mesothelioma. Administration of fibrous particles to laboratory animals has included, in addition to inhalation, intratracheal instillation and intracavitary implantation and instillation. Inhalation studies are difficult to conduct due to the problems associated with the generation and characterization of the fibers during all phases of the assay. 

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