Temperature-dependent luminescence spectroscopic investigations of uranyl(vi) complexation with the halides F- and Cl.

In the present study we have investigated the complexation of uranyl(vi) with chloride and fluoride using luminescence spectroscopy (TRLFS, time-resolved laser-induced fluorescence spectroscopy). At 25 °C (298.15 K), in the presence of 0-0.175 M fluoride, the first single-component emission spectra for all four uranyl(vi)-fluoride complexes, i.e. UO2F+, UO2F2, UO2F3-, and UO2F42- could be extracted. Based on the aqueous speciation derived from the TRLFS data, log K* values at I = 1 M were calculated for all these complexes and extrapolated to infinite dilution using the SIT approach. In the case of chloride, however, quenching of the uranyl(vi)-luminescence hampered the experiments. Thus, uranyl(vi)-complexation was studied with TRLFS at liquid nitrogen temperatures. Samples were prepared at 25 °C (298.15 K) with chloride concentrations ranging from 0 to 1.0 M followed by instantaneous freezing and subsequent luminescence spectroscopic measurements at -120 °C (153.15 K). This allowed for the determination of the first luminescence spectra for the UO2Cl+ complex with the TRLFS method. The chloride quench reaction was further studied in the temperature range 1-45 °C (274.15-318.15 K) using Stern-Volmer analysis. By applying the Arrhenius and the Eyring equations we obtained the first thermodynamic parameters for the dynamic quench process, i.e. the activation energy (Ea = 55.0 ± 12.9 kJ mol-1), enthalpy (ΔH‡ = 52.5 ± 13.0 kJ mol-1), and entropy (ΔS‡ = 103.9 ± 42.8 J mol-1 K-1).

Complexation of Trivalent Lanthanides (Eu) and Actinides (Cm) with Aqueous Phosphates at Elevated Temperatures.

In this study, the complexation of Eu(III) and Cm(III) with aqueous phosphates was investigated using laser-induced luminescence spectroscopy. Experiments at 25 °C and different ionic strengths (0.6-3.1 mol·L-1 NaClO4) established the formation of EuH2PO42+ and CmH2PO42+. From the conditional stability constants, the respective values at infinite dilution as well as the ε(Me(H2PO4)2+;ClO4-) (Me = Eu or Cm) ion interaction coefficients (using the specific ion interaction theory - SIT) were derived. Further experiments (at constant ionic strength of 1.1 mol·L-1) showed that upon increasing the temperature (25-80 °C), the formation of both EuH2PO42+ and CmH2PO42+ was favored. Using the van't Hoff equation, the molal enthalpy Δ R H m° and molal entropy Δ R S m° of these reactions were derived, corroborating an endothermic and entropy driven complexation process. This work contributes to a better understanding of the coordination chemistry of both trivalent lanthanides and actinides with phosphate ions.

[Osteosynthesis of fractures of the coxal femoral end with the dynamic compression hip screw]. / Osteosynthesen von Frakturen am koxalen Femurende mit der dynamischen Hüftkompressionsschraube (DHS).

Results of 179 surgical osteosynthetic procedures applying the dynamic hip screw (DHS) are reported. 103 (65.2) patients were able to walk with or without cane after hospital discharge. 48 (30.4%) patients dependent on an assisting person while 7 (4.4%) patients are not able to walk at all. 46 patients had been controlled clinically in a time-period of 4 months up to 6 years post-surgically. Results indicate an ideal application of the DHS for intertrochanteric femoral fractures, whereas it's application is limited to all other types of femoral fractures occurring near the capital region. The DHS proves to be suited to either avoid or postpone prosthesis in very young patients; it also can be favoured for high aged patients with short life-expectancies in femoral neck fractures of the medial and lateral type.

[Diagnosis and surgical tactics in adrenal gland tumors]. / Diagnostik und Operationstaktik bei Nebennierentumoren.

Adrenal tumours are relatively rare. For localisation and reliable identification, stepwise radiological or nuclearmedical diagnosis should be added to targeted endocrinological diagnosis. Highest accuracy has been recordable from computed tomography, followed by phlebography, and arterial angiography. The authors feel that the extraperitoneal, lumbar approach can be considered a non-invasive, low-complication surgical method. It should be applied more often to cope with benign unilateral adrenal processes.

Organophosphate detoxicating hydrolases in different vertebrate species.

Phosphorylphosphatase activities in various organs of vertebrate species from different classes were determined using a spectrophotometric assay for paraoxonase (EC 3.1.1.2) and a potentiometric assay with a fluoride sensitive electrode for DFPase (EC 3.8.2.1). Temperature-dependent inactivation experiments, an extended interpretation of mixed substrate studies and activity distribution patterns confirm that in vertebrate tissue at least two different enzymes are responsible for hydrolytic detoxication of paraoxon and DFP. Total organophosphate detoxicating phosphorylphosphatase activity of a certain animal species is shown to be the major determinant for differences between the inhibitory potency of organophosphorus compounds on the animal's target enzymes in vitro and organophosphate toxicity in vivo.

[Enzymatic detoxication of organophosphorus insecticides and nerve gases in primates]. / Die enzymatische Entigiftung von phosphororganischen Insektiziden und Nervengasen in Primaten.

The detoxication of organophosphorus compounds by phosphorylphosphatases was studied in primates. Taking into account the distribution of paraoxonase (EC 3.1.1.2) and DFPase (EC 3.8.2.1) in different tissues of the monkey (Macaca mulatta), the total detoxicating capacity for diethyl-p-nitrophenylphosphate (paraoxon, E 600) and diisopropylphosphorofluoridate (DFP) was determined. Acetylcholinesterase (AChE) (EC 3.1.1.7) of human brain was inhibited in vitro by paraoxon and DFP. Using the rate constants of AChE-inhibition and of AChE-synthesis those concentrations of organophosphorus inhibitors were calculated, which in vivo would reduce the steady-state AChE-activity to 20% of normal. This acute ineffective concentration is 7.6 X 10(-8) g/kg for DFP and 2.3 X 10(-8) g/kg for paraoxon. From substrate kinetics of the phosphorylphosphatases the time course of paraoxon and DFP detoxication in primates could be calculated. The time needed by phosphorylphosphatases to reduce a certain dose of an organophosphorus compound to the acute ineffective concentration is referred to as "effective detoxication time". The effective detoxication time (teff) was determined for different concentrations of paraoxon and DFP and was compared with the time needed by these organophosphate concentrations to inhibit AChE-activity to 12.5% of normal (t1/8). The significance of in vitro data for the evaluation of dose limits of organophosphate toxicity in vivo is discussed.

Comparative study of nitroglycerin and molsidomine. Effects on the integrated systemic venous bed and the arterial pressure in dogs.

The effect of nitroglycerin, N-carboxy-3-morpholino-sydnonimine-ethylester (molsidomine, Corvaton), and its metabolite 3-morpholinosydnonimine upon the peripheral circulation was investigated in 38 dogs with cardio-pulmonary bypass. The three compounds increased the integrated systemic venous blood volume and decreased the mean arterial pressure. The time course of the action of nitroglycerin was different from that of molsidomine: The arterial and venous effects of nitroglycerin began immediately after the injection was started, reached a maximum, and had disappeared after 7 min. The effects of molsidomine started later and showed no tendency to decrease during the observation period of 30 min. When referred to the same decrease in arterial blood pressure, molsidomine acted more strongly upon the systemic venous bed than did nitroglycerin. The arterial and venous effects of the molsidomine metabolite could be antagonized by a dopamine infusion. It is concluded that the hypotensive effect of the three compounds observed in the intact circulation is due to the diminuation of peripheral resistance as well as to the dilatation of the systemic venous bed. The dilatation of the veins effects a decrease in the venous return and thereby in the cardiac output and the arterial pressure. It can be concluded that the antianginal effect of the three compounds is not only due to the diminution of the afterload of the heart; the diminution of the heart; the diminution of the preload also represents an important component of action.