Amorphous dust

When the electrolyte solutions are not too reactive, as in the case of ethereal solutions, there is no massive formation of protective surface films at potentials above Li intercalation potential, and most of the solvent reduction processes may occur at potentials lower than 0.3 V vs. Li/Li+. Hence, the passivation of the electrodes is not sufficient to prevent cointercalation of solvent molecules. This leads to an exfoliation of the graphite particles into amorphous dust (expholiated graphene planes). This scenario is demonstrated in Figure 2a as the reduction of the 002 diffraction peak21 of the graphite electrode, polarized cathodically in an ethereal solution. 

For most appHcations, bismuth vanadate is not thermally or chemically stable enough, and it has to be encapsulated with a dense, amorphous shell of sihca (40,41). It is recommended that bismuth vanadate be granulated to improve its handling and eliminate any dusting problems. 

Inhalation of crystalline or fused vitreous silica dust, usually overlong periods, causes a disabling, progressive pulmonary disease known as silicosis (84). Amorphous siUcas have not been linked to siUcosis (85), but can cause respiratory irritation. The history and poHtics of siUcosis have been reviewed (86). Standards have been set or recommended for occupational exposures (87,88) and review articles on the health effects of siUca are available (83,89). 

Amorphous sihca is classified by the Occupational Safety and Health Administration as a nuisance dust. The principal reported health reaction is contact dermatitis resulting from the absorption of protective oils from the skin (1). 

A soft, gritty amorphous silica composed of minute siliceous skeletons of small aquatic plants. Used in filtration and decoloration of liquids, insulation, filler in dynamite, wax, textiles, plastics, paint, and rubber. Calcined and flux-calcined diatomaceous earth contains appreciable amounts of cristobalite, and dust levels should be the same as for cristobalite. 

Silane, see Silicon tetrahydride Silica, Amorphous Total inhalable dust Respirable dust Precipitated... 

Silica, amorphous Silica, crystalline Silica in coal mine dust Silicon... 

Freudenberg has obtained one nitrogen-free product, C13H24O, b.p. 215-220°, by the distillation of aconitine or amorphous aconitine with barium hydroxide or zinc dust. He suggests that the fundamental hydrocarbon, C20H33, may contain two five-membered and four six-membered rings, which will include nine secondary carbon atoms. 

On distillation with zinc dust the alkaloid gives an easily hydrogenated pyrrole base, and on dehydrogenation by platinised asbestos at 260-290 it yields (1) an amorphous dehydro-base, which forms an oxime and a methiodide, C17H23O4N. Mel, decomp. 227-8 , and contains a lactone and a methoxyl group, (2) a neutral pyrrole derivative, and (3) an acid giving a dark green colour with ferric chloride (1939). 

Long exposure to Si02 dust can result in fibrosis of the lung or silicosis which may eventuate in pulmonary hypertension and cor pulmonale. Susceptibility to tuberculosis is enhanced. The tolerance level for cryst forms of Si02 is calculated from the formula 250/(%SiO2 +5), and for amorph forms the tolerance level is 20 millions of particles/cu ft of air... 

Around 10% of the dust consists of carbon particles which are about 0.005 pm in diameter. These are amorphous, carbon-containing solids, probably also containing hydrogen. 

The pathological hallmark of the disease is the presence in the brain of Lafora bodies round, basophilic, PAS-positive intracellular inclusions varying in size from small, dust-like bodies less than 3 nm in diameter to large bodies up to 30 nm in diameter. Lafora bodies are typically seen in neuronal perikarya and processes, not in glial cells, and are more abundant in cerebral cortex, substantia nigra, thalamus, globus pallidus and dentate nucleus. Ultrastructural studies have shown that Lafora bodies consist of two components amorphous electron-dense... 

When supersaturated fresh gallbladder bile (or model bile) is centrifuged to remove solid crystalline and amorphous precipitates, and supernatant vesicles, and the resultant isotropic (one phase) solution maintained in a dust-free environment at 37 °C and examined daily by light microscopy, cholesterol crystals can be observed to precipitate. The time taken for these solid cholesterol... 

The nuisance dust aspect of bauxite is in sharp contrast to the limited industrial situation where lung injury was reported in Canadian workers, who in the 1940s engaged in the manufacture of alumina abrasives in the virtual absence of fume control. Fusing of bauxite at 2000°C gave rise to a fume composed of freshly formed particles of amorphous silica and aluminum oxide. Despite the poor choice of the term—bauxite fume pneumoconiosis—sometimes used to describe the disease, scientific opinion favors the silica component as the probable toxic agent. It should be emphasized that bauxite from some sources may contain small amounts of silica. 

The 2003 ACGIH proposed threshold limit value-time-weighted average (TLV-TWA) for amorphous silica, natural diatomaceous earth, is lOmg/m for the inhalable particulate and 3mg/m for respirable dust containing no asbestos and <1% quartz. 

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