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Toxic Responses of the Lung
Published in Stephen K. Hall, Joana Chakraborty, Randall J. Ruch, Chemical Exposure and Toxic Responses, 2020
Baritosis is a benign pneumoconiosis that results from the inhalation of dusts of barium sulfate or barium ores. The main ore of barium is baryte. Baryte is used principally as a constituent of lithopone, a white pigment employed in the manufacture of paints. It is also used as a filler in textiles, rubber, soaps, cements, and plasters. Barium is highly insoluble and radiopaque, which allows it to be used safely as a radiographic contrast medium. The inert dust of barium compounds in nonfibrogenic and baritosis is not associated with any respiratory symptoms or functional impairment. However, the radiographic appearances are quite striking. The deposits of barium appear as multiple, dense, small, rounded opacities.
Study on the performance of petroleum coke after electrolytic desulfurization in NaBr-CH3COOH system
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Yong Zhang, Qi Yu, Huanhuan Wang, Mingxu Zou
It is difficult to completely remove organic sulfur from petroleum coke because of its complex structure of macromolecules. Not only in tiophene and its derivatives, but the sulfur can be present in the inorganic sulfur forms which comprise of sulfides (e.g. pyrite, marcasite) and sulfates (gypsum, baryte etc). The organic sulfur compounds in bitumen are represented by: thiols, sulfides, disulfides, thiophenes, benzothiophenes, dibenzothiophenes, benzo [b] naphtho [d] thiophenes, etc(Spajić et al. 2021), which may be bound to the aromatic carbon skeleton located between the aromatics. It is difficult to remove the organic sulfur on the surface of the upper, aromatic structure or the connected carbon chain, especially on the aromatic structure (Si and Choi 2000). Researchers have developed a variety of desulfurization methods: calcination method (Zhong et al. 2018), medium gas method (Xiao et al. 2016), chemical desulfurization (Masri 2020), microbiology (Nt, Rss, and Cdh 2019), microwave method (Zhao et al. 2018) although the method of desulfurization before combustion, but the method that can be applied to industrial-scale production has yet to be developed.
Advanced Friction–Wear Behavior of Organic Brake Pads Using a Newly Developed System
Published in Tribology Transactions, 2019
In Figs. 12 and 13, the friction surfaces of all samples appeared to be very similar and were randomly covered with various irregularly dispersed dusts. The SEM micrographs clearly showed that the friction contact had occurred on the friction layer for both the cold and hot braking cases. During the friction tests, the sliding contact between the pad and disc was ensured along the thin friction layer. Wear debris was formed and secondary plateaus can also be observed on the worn surface of brake pad samples in Figs. 13a–13d. This can be attributed to the wollastonite and mica + silica. In addition, barium sulfate (baryte), a common filler utilized in brake pads to impart heat stability to the brake friction material, appeared on the worn surfaces. Interestingly, a different wear mechanism was observed in the SEM micrographs in Fig. 13. There were microcracks on the worn surfaces on the brake pad samples, and plastic deformation associated with microcracks was observed. This situation can be explained by the high amount of material particles fractured from the matrix. Compared to the SEM micrographs of the friction surfaces in Fig. 12, the SEM micrographs in Fig. 13 have a more homogeneous composite structure. In contrast to the micrograph in Fig. 12, the organic fiber of hazelnut or petro-coke dust can be observed in the micrograph in Fig. 13. Wear debris particles and scratches are also common for each of the two microstructures.
Trap creation, trap conversion and thermoluminescence process in barite – effect of flux
Published in Radiation Effects and Defects in Solids, 2020
J. Nandha Gopal, Bhaskar Sanyal, Arunachalam Lakshmanan
Barite (BaSO4), the most common barium mineral, occurs in depositional environments on the seafloor, as well as in those on land including biogenic, hydrothermal, and evaporation on land. The name barite is derived from the Greek word βαρύς (heavy) (1). It is one of just a few nonmetallic minerals with a specific gravity of four or higher. Barite is used in radiology for x-rays of the digestive system. Mineral Barite is one of the first luminescent material from which the famous ‘Bologna stone’ (BaS) was obtained (2, 3). Pure baryte is white opaque to transparent but impurities cause a wide variation in color (4). Radiation damage also causes coloration. For example, O– (in some blue crystals), (in some honey yellow and blue crystals) and (in yellow crystals) centers have been identified in irradiated barite. The intrinsic luminescence center (LC) of appears at 360 nm in all types of sulfates but is absent in sulfates with large quantities of impurities. Thermogravimetric analysis (TGA) of Indian Barite Mineral carried out in a nitrogen atmosphere has shown the onset of weight loss due to thermal decomposition on heating above 1000°C (4). BaSO4 as a matrix for CdTe quantum dots useful in solid-state lighting is recently reported (5). The BaSO4 matrix ensured the protection of the CdTe QDs from the surrounding environment and, as a result, provides the CdTe@BaSO4 powders with excellent optical properties, including strong red photoluminescence (PL), long fluorescent lifetime, and high photo- and thermal stability, as well as anti-acid properties. Doped BaSO4 phosphors synthesized by solid-state reaction or co-precipitation routes have been extensively studied for their PL, thermoluminescence (TL) and optically stimulated luminescence (OSL) properties and other applications – BaSO4:Sm3+/Eu2+ (6, 7), BaSO4:Tb3+ (8), BaSO4:Eu2+ (9–12), BaSO4:Bi2+ (13) and (Ba,Sr)SO4:Eu2+ (14). Gupta et al. (15) report that in impurity doped BaSO4 made by precipitation route, anion radicals (such as , , and ) that act as trapped hole centers were formed by γ-irradiation. Thermally released holes from each of such centers are mobile and recombine at some trapped electron centers to cause high-temperature TL peaks. The energy thus released excites the impurity ion present, which on returning to the normal state gives its characteristic emission. No attempt was, however, made to identify the electron centers.