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Signalling Flare Compositions
Published in Ajoy K. Bose, Military Pyrotechnics, 2021
Infusing chlorine also allows more magnesium to react with chlorine to form MgCl, which is invisible and does not affect colour formed due to strontium monochloride. Further, presence of carbon provided by chlorine donors also allows any MgO formed to react and form Mg vapour and CO which does not affect colour. These chlorine donors also cool the flame, so that white light does not overpower the red light due to strontium monochloride. It also reduces the reaction rate for proper burn rate. The chlorine formed during combustion at high temperature also reacts with any strontium oxide (formed, if any) to form strontium monochloride. Hence, these signal compositions are required to be made in negative oxygen balance to avoid formation of strontium oxide. Some of the red signalling flare compositions are given in Table 9.4.
Advances in Primary and Revision Hip Arthroplasty
Published in K. Mohan Iyer, Hip Joint in Adults: Advances and Developments, 2018
Shibu P. Krishnan, G. Gopinath
Biolox delta is a zirconia-toughened alumina ceramic. An earlier design Biolox forte was made of alumina with a small proportion of magnesium oxide. The addition of zirconium to create Biolox delta increased the fracture toughness of alumina. Biolox delta contains 82% alumina, 17% zirconium oxide, 0.3% chromium oxide and 0.6% strontium oxide [3]. It was initially introduced for use as femoral heads only and more recently expanded to use as Biolox-delta-onBiolox-delta bearings in total hip arthroplasty (THA). Because of its increased fracture toughness and burst strength, it is expected to reduce the estimated fracture risk of alumina ceramic (Biolox forte) heads (0.02% is the fracture risk for Biolox forte heads). A wider range of head sizes is available with Biolox delta compared to Biolox forte.
Light Sources
Published in Toru Yoshizawa, Handbook of Optical Metrology, 2015
The excited electrons become trapped in the triplet state (a metastable state) for prolonged period of time, which causes substantial delay between excitation and emission. Although most phosphorescent compounds de-excite rather quickly (on the order of milliseconds), there are certain crystals as well as some large organic molecules, which remain in a metastable state sometimes as long as several hours. These substances effectively store light energy, and if the phosphorescent quantum yield is high, they release significant amounts of light over long time, creating an afterglow effect. The metastable states could be populated also via thermal excitation; therefore, phosphorescence is temperature-dependent process. Common pigments used in phosphorescent materials include zinc sulfide and strontium oxide aluminate. Since strontium oxide aluminate has a luminance approximately 10 times greater than zinc sulfide, it is used widely in safety-related signage (exit signs, pathway marking, and other).
Earth-Based Building Materials. The First Use of Clay Mortars and Adobes in Antiquity in Cyprus
Published in International Journal of Architectural Heritage, 2022
The chemical analysis of the majority of adobes under study (Table 5) showed similar results with the analyses of clay mortars. Specifically, a high percentage of CaO ranging between 18–46%, and silica SiO2 ranging between 10–49%, with a moderately high concentration of alumina Al2O3 ranging between 2–12%, was observed. Nevertheless, the concentration of silica in the majority of samples ranged from ca. 30–40% and of alumina from ca 10–20%. The appearance of some other elements in smaller concentrations, such as Fe and Mg, was also reported, as well as Na, K and Mn. In most of the samples from Kalavasos-Tenta and Khirokitia, a rather high percentage of sulphur trioxide was found, despite the significantly low concentrations of this particular element in all other samples. Additionally, in the samples of Khirokitia, a high concentration of strontium oxide (SrO) was observed (Table 5).