Über Grundwasserströmungen

Ohne Zusammenfassung     

Viscositsmessung an wässerigen Zucker- und Natriumphosphatlösungen

Ohne Zusammenfassung The online version of the original article can be found at     

Neuroprotective Effect of Quercetin during Cerebral Ischemic Injury Involves Regulation of Essential Elements,Transition Metals,Cu/Zn Ratio,and Antioxidant Activity

Cerebral ischemia results in increased oxidative stress in the affected brain. Accumulating evidence suggests that quercetin possesses anti-oxidant and anti-inflammatory properties. The essential elements magnesium (Mg), zinc (Zn), selenium (Se), and transition metal iron (Fe), copper (Cu), and antioxidants superoxide dismutase (SOD) and catalase (CAT) are required for brain functions. This study investigates whether the neuroprotective effects of quercetin on the ipsilateral brain cortex involve altered levels of essential trace metals, the Cu/Zn ratio, and antioxidant activity. Rats were intraperitoneally administered quercetin (20 mg/kg) once daily for 10 days before ischemic surgery. Cerebral ischemia was induced by ligation of the right middle cerebral artery and the right common carotid artery for 1 h. The ipsilateral brain cortex was homogenized and the supernatant was collected for biochemical analysis. Results show that rats pretreated with quercetin before ischemia significantly increased Mg, Zn, Se, SOD, and CAT levels, while the malondialdehyde, Fe, Cu, and the Cu/Zn ratio clearly decreased as compared to the untreated ligation subject. Taken together, our findings suggest that the mechanisms underlying the neuroprotective effects of quercetin during cerebral ischemic injury involve the modulation of essential elements, transition metals, Cu/Zn ratio, and antioxidant activity.     

The transport properties of binary mixtures of hydrogen with CO,CO2 and CH4

The paper presents new, absolute measurements of the viscosity and thermal conductivity of mixtures of hydrogen with carbon monoxide, carbon dioxide and methane near room temperature. The viscosity measurements have been performed at a pressure of 0.1 MPa and have an estimated accuracy of ±0.1%. The data have been employed to evaluate quantities characteristic of the unlike interaction, including the binary diffusion coefficient. These results allow the thermal conductivity to be calculated with the aid of the appropriate kinetic-theory expressions. The calculations have been performed for both the zero-density limit and over the range of pressures encompassed by the measurements (0.8–12 MPa). It has not proved possible to represent the experimental thermal conductivity data within their uncertainty of ±0.3% by means of the available kinetic-theory equations. This finding is attributed to the fact that the equations employed are not as accurate as the experimental data for systems in which the mass ratio of the species differs substantially from unity.     

Ground state energy of spin polarized hard core neutron matter

The expansion of the ground state energy of spin polarized hard core neutron matter in powers of x =k_Fc (k_F = Fermi momentum, c = hardcoreradius) is calculated up to terms ≈x⁸.     

Elektrolytische Herstellung von Zyklotrontargets der Seltenerdmetalle

Für Zyklotronbestrahlungen von Seltenerdmetallen (SE) ist es erforderlich, das gewünschete Element in geeigneter Form auf einer Platinunterlage aufzutragen. Durch Aufstreichen von SE-Nitraten, die anschlißend bei 900 … 1000°C zu Oxiden verglüht werden, erhält man fest haftende Schichten. Die Methode ist jedoch bei teuren getrennten Isotopen verschwenderisch.     

Evaluation of excess volume in UO2(NO3)2 · 6H2O-HNO3-H2O ternary mixture

In order to obtain the exact information of atomic number density in UO₂(NO₃)₂ · 6H₂O–HNO₃–H₂O ternary mixture, the theoretical estimation of excess volume which is one of excess properties of non-ideal solution is discussed in this study. The calculation model based on the Stokes-Robinson application of the Brunauer-Emmett-Teller (BET) adsorption isotherm and activity equations of water nitric acid, and uranyl nitrate hexahydrate (UNH) which were used to calculate distribution coefficients in a solvent extraction system has one adjustable parameter and two BET constants. The BET constants have been determined by asymptotic method on the BET adsorption isotherm as a function of water activity in the ternary system. As results of the study, the observed volume of mixture agrees with the volume predicted by the simulation within a maximum relative deviation of 0.78% and the excess volume is also estimated as a function of total molality.     

Integration of metrological principles in a proficiency-testing scheme in the field of water analysis

Measurement traceability is universally recognised as one of the basic prerequisites for comparability of results obtained in different laboratories and is a basic aspect of metrological sciences such as analytical chemistry. This requirement is underscored by the increasing adoption of standards and measurement quality systems, such as laboratory accreditation against ISO/IEC 17025. Testing laboratories ensure traceability of their measurement results by using appropriate reference standards for calibration of instruments and control of measurement processes. For routine work in the field of water analysis, these standards are usually commercial solutions or in-house solutions prepared from pure products. Therefore, laboratories should demonstrate that their use of reference standards is appropriate and sufficient, which can be done by participation in an appropriate proficiency-testing scheme. The paper reports how measurement traceability of results from field laboratories (nitrite nitrogen, nitrate nitrogen, chloride and sulphate; all in water) can be demonstrated by participation in a proficiency-testing scheme based on reference values.     

1-methyl-2-undecyl-4(1H)-quinolone as an irreversible and selective inhibitor of type B monoamine oxidase

The inhibitory compound of monoamine oxidase (MAO) activity was isolated from the CH(2)Cl(2) fraction of the fructus of Evodia rutaecarpa and identified as 1-methyl-2-undecyl-4(1H)-quinolone (1). Compound 1 showed a selective inhibition of type B MAO (MAO-B) activity with the IC(50) value of 15.3 microM using a substrate kynuramine, but did not inhibit type A MAO (MAO-A) activity. The kinetic analysis using Lineweaver-Burk plots indicated that compound 1 competitively inhibited MAO-B activity with the K(i) value of 9.91 microM. The inhibition of MAO-B by compound 1 was found to be irreversible by dialysis of the incubation mixture. These results suggest that compound 1 is a potent irreversible inhibitor of MAO-B, and may regulate catecholamine content in the neurons.