Net calcium flux (JCa) from bone in vitro is pH dependent. When pH falls below 7.40, through a reduction in [HCO3-], there is both physicochemical and cell-mediated JCa. To characterize the physicochemical effect of acidosis on bone we inhibited the bone-resorbing cells (osteoclasts) with the specific inhibitor calcitonin and studied the effect of acidosis on JCa and bone ion composition using an analytic high-resolution scanning ion microprobe. Neonatal mouse calvariae were cultured for 48 h in physiologically neutral pH medium (Ntl, pH = 7.41, [HCO3-] = 25 nM) or in medium that modeled metabolic acidosis (Met, pH = 7.10, [HCO3-] = 12), each with or without calcitonin (CT, 3 x 10(-9) M). There was net calcium efflux in Ntl (JCa = 631 +/- 36 nmol per bone per 48 h), which increased in Met (1019 +/- 53, p < 0.01); CT inhibited JCa in Ntl (-54 +/- 11, p < 0.01 versus Ntl), which increased in Met (197 +/- 15, p < 0.01 versus Ntl + CT). In the presence of CT the increase in JCa in Met versus Ntl represents physiochemical bone dissolution. The Ntl bone surface (approximately 2 nm in depth) was rich in Na compared to Ca (Na/Ca = 11.9, count/s of detected secondary ions), which fell in Met (Na/Ca = 6.0, p < 0.05); CT caused a further reduction of Na/Ca (3.1, p < 0.01 versus Ntl and versus Met), which was not altered in Met (2.6, p < 0.05 versus Ntl + CT).(ABSTRACT TRUNCATED AT 250 WORDS)

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The results of a systematic study of photoluminescence (PL) properties of un‐doped sapphire crystals grown using different starting materials on various crystal growth methods (CZ, EFG, HDSM, Kyropoulus, HEM) are presented. Narrow line of emission has been attributed to radiation transition in Cr3+ ions (R‐line), while the nature of red wide band (RWB) of emission (600‐850 nm) is still under question. Integral intensities of R‐line and RWB were analyzed and their dependences on type of starting raw materials and of the method of crystal growth were shown. The crystals grown using Vernuil starting material exhibited significant PL in all utilized methods. On the contrary, sapphire samples grown by the same technologies wherein EMT HPDAR (High Purity Densified Alumina) was the starting material revealed much lower PL. HPDAR is produced by EMT, Inc. with proprietary and patented technology. The concentrations of various metal impurities such as Ca, Mg, Zn, Cu, Cr, Fe, Ni, H were measured. Effect of these impurities on luminescence intensity and especially the role of hydrogen incorporated into sapphire lattice are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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