A reinvestigation of alloxan-like compounds derived from uric acid

The structures of two isomeric intermediate in the oxidative conversion of uric acid ($\text{1}$) to alloxan ($\text{5}$) are revised and the compounds shown to be uric acid glycol ($\text{3}$) and 5-hydroxy-pseudouric acid ($\text{4}$), respectively.     

Complexation of uranium(VI) with protocatechuic acid—application of iterative transformation factor analysis to EXAFS spectroscopy

The speciation of 1 mM uranium(VI) in carbonate-free aqueous solutions of 50 mM protocatechuic acid (PCA, 3,4-dihydroxybenzoic acid) was studied in the pH range of 4.0 to 6.8 using EXAFS spectroscopy. The uranium L_III-edge EXAFS spectra were analyzed using a newly developed computer algorithm for iterative transformation factor analysis (FA). Two structural different uranium(VI) complexes were observed. The speciation in the pH range of 4.0 to 4.8 is dominated by a 1:2 or 1:3 uranium(VI)/PCA complex with bidentate coordination of the carboxyl group to the uranium(VI) moiety. Already at pH 4.6 significant amounts of a second species are formed. This uranium(VI) species contains two PCA ligands that are bound to the uranium via their neighboring phenolic hydroxyl groups under formation of five-member rings.     

Precipitation of aluminium hydroxide in the presence of surfactant and its effect on the surface acidity

Surface acidity of aluminas prepared by precipitation from sodium aluminate solutions and nitric acid with and without surfactant were determined by IR spectroscopy. It was found that the amounts of aprotic acidic sites increase with increasing pH of precipitation and with increasing concentration of surfactant used in the course of precipitation and washing of the precipitate.

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Microspectrometric Investigation of Petrified Wood from South-Eastern Poland

 The investigation of the interesting collection of the petrified wood from Bondyrz, Roztocze, south-eastern Poland, has been continued. Two kinds of microprobes such as electron microprobe from the Catholic University of Lublin and synchrotron-based X-ray microprobe from LURE, Orsay, were applied to detect the elements associated with the main component – silica and their spatial distribution and interrelations. The distribution of carbon in the petrified material has been established, which is important since that element is the main remains from the history of the trees. The carbon distribution was characteristic – it concentrated on a place of primordial dark wood. The distribution patterns of the other elements were either similar to that of carbon (Cu, Pb) or they concentrated in separate inclusions (Fe, Al, K, Na, Ca). The replicating mode of the original wood pattern in silica and carbon-containing material was explained. Some indications about the composition of the primordial petrifying solution, the rate of the petrifaction process and the recent coloration of the sample could be concluded from the compositional patterns of silica. The boundary between totally and partially petrified zones could be well observed. Received October 2000. Revision March 6, 2001.     

Higgs bosons in nonlinearly realized supersymmetry

Using the formatlism developed by Samuel and Wess a general form of the Higgs potential in nonlinearly realized supersymmetric extention of the Standard Model in curved space is constructed. In flat space limit we derive bounds for Higgs boson masses and mass relations. Comparisons to the linear supersymmetric models MSSM and NMSSM are made.     

A classical analysis of quantum resonances in isotopic collinear H + H2 reactions

Isotopic substitution of hydrogen by muonium in the collinear H + H₂ reaction causes dramatic changes in the resonance patterns of the quantum reaction probabilities. These changes are explained by a classical model. Using the systems' resonant orbits, we show that resonances appear close to energetic thresholds of new vibrational channels.     

Transporteigenschaften von 9 bin?ren und 2 tern?ren Mischungen von Gasen bei niederer Dichte

Ohne Zusammenfassung     

Components of superspace

We give the explicit superspace form of the newly discovered tensor calculus for the chiral multiplet [1].