نتایج جستجو برای: beryllium compounds
تعداد نتایج: 229129 فیلتر نتایج به سال:
Chronic beryllium disease (CBD) is a granulomatous lung disease that occurs primarily in workers who are exposed to beryllium dust or fumes. Although exposure to beryllium is a necessary factor in the pathobiology of CBD, alleles that code for a glutamic acid residue at the 69th position of the HLA-DPbeta1 gene have previously been found to be associated with CBD. To date, 43 HLA-DPbeta1 allele...
Despite more than 20 years of surveillance and epidemiologic studies using the beryllium blood lymphocyte proliferation test (BeBLPT) as a measure of beryllium sensitization (BeS) and as an aid for diagnosing subclinical chronic beryllium disease (CBD), improvements in specific understanding of the inhalation toxicology of CBD have been limited. Although epidemiologic data suggest that BeS and ...
Chronic beryllium disease is predominantly a pulmonary granulomatosis that was originally described in 1946. Symptoms usually include dyspnea and cough. Fever, anorexia, and weight loss are common. Skin lesions are the most common extrathoracic manifestation. Granulomatous hepatitis, hypercalcemia, and kidney stones can also occur. Radiographic and physiologic abnormalities are similar to those...
C hronic beryllium disease (CBD) appeared to be waning 30 yrs ago [1]. In 1980, less than one case per year was reported and the incidence rate per ton of beryllium produced had declined from between five and 10, to less than 0.001. CBD appeared to be heading toward the medical archives as a success story of environmental control in the absence of understanding of the pathogenesis of the diseas...
The intrinsic acidity of CH2[double bond, length as m-dash]CHXH2, HC[triple bond, length as m-dash]CXH2 (X = N, P, As, Sb) derivatives and of their complexes with BeH2 and BH3 has been investigated by means of high-level density functional theory and molecular orbital ab initio calculations, using as a reference the ethyl saturated analogues. The acidity of the free systems steadily increases d...
Plateaus in water adsorption isotherms on hydroxylated BeO surfaces suggest significant differences between the hydroxylated (100) and (001) surface structures and reactivities. Density functional theory structures and energies clarify these differences. Using relaxed surface energies, a Wulff construction yields a prism crystal shape exposing long (100) sides and much smaller (001) faces. This...
A previously unknown thermodynamically stable high-pressure phase of BeF2 has been predicted using the evolutionary algorithm USPEX. This phase occurs in the pressure range 18-27 GPa. Its structure has C2/c space group symmetry and contains 18 atoms in the primitive unit cell. Given the analogy between BeF2 and SiO2, silica phases have been investigated as well, but the new phase has not been o...
In this study, beryllium-copper alloy was subjected to around -150° F for cold treatment and to around -300° F for cryogenic treatment and the effects of these cold and cryogenic treatments on the machinability of beryllium-copper workpieces in electro discharge machining have been investigated. Experimental results showed about 20-30 % increase in material removal rate of cold and cryogenic tr...
introduction: evaluation of bonding in atomic level, by sem/eds analysis of si atoms, is an exact method for determination of bond strength of metal and porcelain. the purpose of this study was to evaluate the bond strength of one noble alloy and two base metal alloys with and without beryllium. methods and materials: six specimens of each alloy begostar, rexillium iii, wiron 99 (10×10×1mm dime...
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