Untersuchungen an Metallkatalysatoren. XIX. Zur katalytischen Wirksamkeit von Ni?Cu?Re-Katalysatoren

Investigations on Metal Catalysts. XIX. Catalytic Efficiency of Ni? Cu? Re Catalysts Alloying of Ni? Cu catalysts with rhenium causes an increased activity in the case of dehydrogenation of cyclohexane as well as the hydrogenolysis of ethane. The catalytic dehydrogenation activity is essentially determined by the f.c.c. phase of the ternary alloy system. In the case of ethane hydrogenolysis, both the f.c.c. and the h.c.p. phases are active, and both are desactivated by copper. The dehydrogenation activity of Ni? Cu? Re samples with medium copper content and low rhenium content is higher by one order of magnitude in comparison with nickel, and their hydrogenolysis activity is considerably lower.     

Photometrische Bestimmung von Phosphat und löslichem Silikat in Umweltproben

Zusammenfassung Phosphat und Silikat sind in salpetersaurer Lösung als Molybdoheteropolysäuren nach Extraktion mit 20%n-Butanol in CHCl₃ bzw. mitn-Amylalkohol hintereinander bei 310 nm bzw. 410 nm spektrophotometrisch bestimmbar. Eine grobe Unterscheidung verschiedener Phosphatanionenspezies gelingt dadurch, daß nach der Bestimmung von Orthophosphat soviel Säure zugesetzt wird, um anorganisch kondensierte Phosphate (Grahamsches Salz), nicht aber organische Phosphate (ATP) zu hydrolysieren. Zur Bestimmung des Gesamtphosphorgehaltes wurde die Probe mit HNO3 aufgeschlossen. Bei unvollständigem Aufschluß von aromatischen Verbindungen muß parallel dazu der jeweilige Blindwert durch Extraktion ohne Molybdatzusatz bestimmt werden. Die Querstörungen durch häufig vorkommende Ionen sind gering.Der Arbeitsbereich der Methode liegt bei 0,2–10g P (als Orthophosphat), 1–20g P (als Ortho-und Polyphosphat) bzw. 5–100g Si (als lösliches Silikat). Die Standardabweichung für 5g P als Orthophosphat beträgt 5%, bei täglicher Eichung 2,6%. Das Verfahren wurde auf die Analyse von Abwässern und Fallstaubdepositionsproben angewendet; die Zuverlässigkeit wurde durch Vergleichsmessungen mit einem Referenzverfahren überprüft.

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Photometric determination of phosphate and soluble silicate in effluents and airborne particles

Summary Phosphate and silicate can be determined from solutions of nitric acid by spectrophotometry at 310 nm or 410 nm resp. after extraction with 20%n-butanol in CHC₃ and subsequently withn-amylalcohol. A coarse differentiation of the various phosphate anions succeeds in addition of as much acid after the determination of orthophosphate, as is needed to hydrolize anorganic condensed phosphates (Graham's salt), but not organic bound phosphate (ATP).To determine the total amount of phosphorus the sample was decomposed. When there is incomplete decomposition of aromatic organic compounds, the reagent blank has to be determined in parallel be extraction without the addition of molybdate. Interference of frequently occurring ions are low.The working range is about 0.2–10g P (as ortho phosphate), 1–20g P (as ortho and poly phosphate) and 5–100g Si (as soluble silicate). The standard deviation for 5g P as ortho phosphate amounts 5%, or 2.6% at calibration daily. The method has been applicated for the analysis of effluents and depositions of airborne particles, the reliability has been checked by a reference method.

     

Untersuchungen an Metallkatalysatoren. XVIII. Zur Phasengestaltung,Dispersität und Oberflächenzusammensetzung von Ni?Cu?Re?Katalysatoren

Investigations on Metal Catalysts. XVIII. Phase Shaping, Dispersity, and Surface Composition of Ni? Cu? Re Catalysts Catalysts of the system Ni? Cu? Re reduced at 500°C consist of the following phases: only one f.c.c. phase in Ni? Cu samples, in Ni? Cu? Re samples with ≥10 at.-% Re there is an additional h.c.p. phase (pure Re). The greatest solubility in regard to rhenium (but never > 10 at.-%) was observed in the case of catalysts with a Ni:Cu ratio of 1:1. Ni? Cu? Re samples show considerably higher surface areas than the nickel sample. The catalyst Ni 45 Cu 45 Re 10 exhibits the maximum surface area. The surface layer of the crystallites is enriched with copper.     

The determination of thallium in rocks and biological materials at ng g−1 levels by differential-pulse anodic stripping voltammetry and electrothermal atomic absorption spectrometry

Thallium is volatilized from biological materials and rocks after admixture with silicic acid and cellulose/magnesium chloride, respectively, by combustion in oxygen in a quartz apparatus, and from rocks after admixture with magnesium chloride by fusion at 1250°C in a quartz tube drawn to a capillary at one end and sealed at the other end. The condensed thallium is dissolved in a small volume of acid which is used directly to determine thallium procedure was found to be 1 ng g^?1 (deposition time 10 min). The results are in satisfactory agreement with those obtained by electrothermal atomic absortion spectrometry after extraction.     

A Beurling-Blecher-Labuschagne Theorem for Noncommutative Hardy Spaces Associated with Semifinite von Neumann Algebras

We prove a Beurling-Blecher-Labuschagne theorem for \({H^\infty}\)-invariant spaces of \({L^p(\mathcal{M},\tau)}\) when \({0 < p \leq\infty}\), using Arveson’s non-commutative Hardy space \({H^\infty}\) in relation to a von Neumann algebra \({\mathcal{M}}\) with a semifinite, faithful, normal tracial weight \({\tau}\). Using the main result, we are able to completely characterize all \({H^\infty}\)-invariant subspaces of \({L^p(\mathcal{M} \rtimes_\alpha \mathbb{Z},\tau)}\), where \({\mathcal{M} \rtimes_\alpha \mathbb{Z} }\) is a crossed product of a semifinite von Neumann algebra \({\mathcal{M}}\) by the integer group \({\mathbb{Z}}\), and \({H^\infty}\) is a non-selfadjoint crossed product of \({\mathcal{M}}\) by \({\mathbb{Z}^+}\). As an example, we characterize all \({H^\infty}\)-invariant subspaces of the Schatten p-class \({S^p(\mathcal{H})}\), where \({H^\infty}\) is the lower triangular subalgebra of \({B(\mathcal{H})}\), for each \({0 < p \leq\infty}\).     

Chemical Perturbation of Oncogenic Protein Folding: from the Prediction of Locally Unstable Structures to the Design of Disruptors of Hsp90–Client Interactions

Protein folding quality control in cells requires the activity of a class of proteins known as molecular chaperones. Heat shock protein-90 (Hsp90), a multidomain ATP driven molecular machine, is a prime representative of this family of proteins. Interactions between Hsp90, its co-chaperones, and client proteins have been shown to be important in facilitating the correct folding and activation of clients. Hsp90 levels and functions are elevated in tumor cells. Here, we computationally predict the regions on the native structures of clients c-Abl, c-Src, Cdk4, B-Raf and Glucocorticoid Receptor, that have the highest probability of undergoing local unfolding, despite being ordered in their native structures. Such regions represent potential ideal interaction points with the Hsp90-system. We synthesize mimics spanning these regions and confirm their interaction with partners of the Hsp90 complex (Hsp90, Cdc37 and Aha1) by Nuclear Magnetic Resonance (NMR). Designed mimics selectively disrupt the association of their respective clients with the Hsp90 machinery, leaving unrelated clients unperturbed and causing apoptosis in cancer cells. Overall, selective targeting of Hsp90 protein–protein interactions is achieved without causing indiscriminate degradation of all clients, setting the stage for the development of therapeutics based on specific chaperone:client perturbation.     

New high precision lifetime measurements in pure copper and a 0.3 at.% AgSb alloy with a BaF2 lifetime spectrometer

The temperature dependence of positron annihilation in copper and a 0.3 at.% AgSb alloy has been investigated by measuring the positron lifetime. In both cases the vacancy lifetime is nearly independent on temperature while the bulk lifetime shows a rapid increase after the onset of detectable vacancies. This increase can be explained by trapping during thermalization with an enhanced trapping rate.