Een 20-jarige man met een luxatie van de grote teen

A 20-year-old student came to our Emergency Department with a dislocated great toe with interposition of the sesamoid bone on the plantair side of the proximal phalanx (Miki Type 2 dislocation). Attempts of closed reduction at the Emergency Room were unsuccessful and open reduction and K-wire fixation was performe

Thallium isotope variations in seawater and hydrogenetic, diagenetic, and hydrothermal ferromanganese deposits

Results are presented for the first in-depth investigation of Tl isotope variations in marine materials. The Tl isotopic measurements were conducted by multiple collector-inductively coupled plasma mass spectrometry for a comprehensive suite of hydrogenetic ferromanganese crusts, diagenetic Fe–Mn nodules, hydrothermal manganese deposits and seawater samples. The natural variability of Tl isotope compositions in these samples exceeds the analytical reproducibility (±0.05‰) by more than a factor of 40. Hydrogenetic Fe–Mn crusts have ϵ205Tl of +10 to +14, whereas seawater is characterized by values as low as −8 (ϵ205Tl represents the deviation of the 205Tl/203Tl ratio of a sample from the NIST SRM 997 Tl isotope standard in parts per 104). This ∼2‰ difference in isotope composition is thought to result from the isotope fractionation that accompanies the adsorption of Tl onto ferromanganese particles. An equilibrium fractionation factor of α∼1.0021 is calculated for this process. Ferromanganese nodules and hydrothermal manganese deposits have variable Tl isotope compositions that range between the values obtained for seawater and hydrogenetic Fe–Mn crusts. The variability in ϵ205Tl in diagenetic nodules appears to be caused by the adsorption of Tl from pore fluids, which act as a closed-system reservoir with a Tl isotope composition that is inferred to be similar to seawater. Nodules with ϵ205Tl values similar to seawater are found if the scavenging of Tl is nearly quantitative. Hydrothermal manganese deposits display a positive correlation between ϵ205Tl and Mn/Fe. This trend is thought to be due to the derivation of Tl from distinct hydrothermal sources. Deposits with low Mn/Fe ratios and low ϵ205Tl are produced by the adsorption of Tl from fluids that are sampled close to hydrothermal sources. Such fluids have low Mn/Fe ratios and relatively high temperatures, such that only minor isotope fractionation occurs during adsorption. Hydrothermal manganese deposits with high Mn/Fe and high ϵ205Tl are generated by scavenging of Tl from colder, more distal hydrothermal fluids. Under such conditions, adsorption is associated with significant isotope fractionation, and this produces deposits with higher ϵ205Tl values coupled with high Mn/Fe

Photochemistry of peroxoborates: borate inhibition of the photodecomposition of hydrogen peroxide

The UV absorbance and photochemical decomposition kinetics of hydrogen peroxide in borate/boric acid buffers were investigated as a function of pH, total peroxide concentration, and total boron concentration. At higher pH borate/boric acid inhibits the photodecomposition of hydrogen peroxide (molar absorptivity and quantum yield of H2O2 and HO2−, (19.0±0.3) m−1 cm−1 and 1, and (237±7) m−1 cm−1 and 0.8±0.1, respectively). The results are consistent with the equilibrium formation of the anions monoperoxoborate, KBOOH=[H+][HOOB(OH)3−]/([B(OH)3][H2O2]), 2.0×10−8, R. Pizer, C. Tihal, Inorg. Chem. 1987, 26, 3639–3642, and monoperoxodiborate, KBOOB=[BOOB2−]/([B(OH)4−][HOOB(OH)3−]), 1.0±0.3 or 4.3±0.9, depending upon the conditions, with molar absorptivity, (19±1) m−1 cm−1 and (86±15) m−1 cm−1, respectively, and respective quantum yields, 1.1±0.1 and 0.04±0.04. The low quantum yield of monoperoxodiborate is discussed in terms of the slower diffusion apart of incipient .OB(OH)3− radicals than may be possible for .OH radicals, or a possible oxygen-bridged cyclic structure of the monoperoxodiborate