Absorption spectra of the nitrosonaphtholsulphonic acid complexes formed with iron(II)

Summary A spectrophotometric study was made of the reactions of iron(II) with nine differento-nitrosonaphtholsulphonates in aqueous solution. The study shows that the green complexes formed by 1-nitroso-2-naphthol-6-sulphonate, 2-nitroso-1-naphthol-4-sulphonate, 2-nitroso-1-naphthol-6-sulphonate, and l-nitroso-2-naphthol-7-sulphonate with iron (II) have slightly higher molar absorptivities than the iron complex formed with the more popular reagent 1-nitroso-2-naphthol-3,6-disodium sulphonate (nitroso-R salt).

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Zusammenfassung Die Reaktionen von Eisen(II) mit neun verschiedeneno-Nitrosonaphtholsulfonaten in wäßiger Losung wurden spektrophotometrisch untersucht. Daraus ergab sich, daß die grünen Komplexverbindungen von l-Nitroso-2-naphthol-6-sulfonat, 2-Nitroso-1-naphthol-4-sulfonat, 2-Nitroso-1-naphthol-6-sulfonat und 1-Nitroso-2-naphthol-7-sulfonat mit Eisen(II) eine etwas stärkere molare Absorption ergeben als die Eisenkomplexe mit dem gebräuchlichen Reagens 1-Nitroso-2-naphthol-3,6-dinatriumsulfonat (Nitroso-R-Salz).

     

Characterization of the alnumycin gene cluster reveals unusual gene products for pyran ring formation and dioxan biosynthesis

Alnumycin is closely related to the benzoisochromanequinone (BIQ) polyketides such as actinorhodin. Exceptional structural features include differences in aglycone tailoring that result in the unique alnumycin chromophore and the existence of an unusual 4-hydroxymethyl-5-hydroxy-1,3-dioxan moiety. Cloning and sequencing of the alnumycin gene cluster from Streptomyces sp. CM020 revealed expected biosynthesis genes for polyketide assembly, but several genes encoding subsequent tailoring enzymes were highly atypical. Heterologous expression studies confirmed that all of the genes required for alnumycin biosynthesis resided within the sequenced clone. Inactivation of genes aln4 and aln5 showed that the mechanism of pyran ring formation differs from actinorhodin and granaticin pathways. Further inactivation studies identified two genes, alnA and alnB, involved in the synthesis and attachment of the dioxan moiety, and resulted in the production of the polyketide prealnumycin.     

Measurement uncertainty in microbiological cultivation methods

Microbiological analyses are carried out on clinical, food, feed and environmental samples. The aims of the analyses are diagnostic or estimation of the safety or the quality of the sample. Important decisions are made on the basis of microbiological analyses. Little attention, however, is paid to the uncertainty of measurement of microbiological analyses. In microbiological cultivation techniques the result is obtained by counting individual objects. The normally low number of counted objects strongly affects the result of the analysis and its uncertainty. Because of the importance of the particle statistical variation to the uncertainty, the approaches developed for chemical analyses are not directly applicable to microbiology. This paper discusses microbial analyses and describes a novel guidance document for the estimation of measurement uncertainty in culturing methods [1]. Received: 7 October 2000 Accepted: 8 March 2001     

The fast diffusion equation with measure data

We show the existence of solutions to the fast diffusion equation with a general finite and positive Borel measure as the right hand side source term.     

Über die Einwirkung des Bromwasserstoffs und der Schwefelsäure auf primäre Alkohole

Ohne Zusammenfassung     

Boundary continuity of solutions to elliptic equations with nonstandard growth

We study regularity properties of weak solutions to elliptic equations involving variable growth exponents. We prove the sufficiency of a Wiener type criterion for the regularity of boundary points. This criterion is formulated in terms of the natural capacity involving the variable growth exponent. We also prove the Hölder continuity of weak solutions up to the boundary in domains with uniformly fat complements, provided that the boundary values are Hölder continuous.     

Halogenated xenon cyanides ClXeCN, ClXeNC, and BrXeCN

We report on the preparation and characterization of three new noble-gas molecules ClXeCN, ClXeNC, and BrXeCN. These molecules are synthesized by 193 nm photolysis and thermal annealing of ClCN and BrCN in a xenon matrix. The absorption spectra are measured in the mid- and far-infrared regions, and the assignment is supported by isotope substitution and quantum chemical calculations at the B3LYP and MP2 levels of theory. The present results demonstrate a way to prepare other noble-gas molecules of this type.     

Nuclear spin optical rotation and Faraday effect in gaseous and liquid water

Nuclear spin optical rotation (NSOR) of linearly polarized light, due to the nuclear spins through the Faraday effect, provides a novel probe of molecular structure and could pave the way to optical detection of nuclear magnetization. We determine computationally the effects of the liquid medium on NSOR and the Verdet constant of Faraday rotation (arising from an external magnetic field) in water, using the recently developed theory applied on a first-principles molecular dynamics trajectory. The gas-to-liquid shifts of the relevant antisymmetric polarizability and, hence, NSOR magnitude are found to be -14% and -29% for (1)H and (17)O nuclei, respectively. On the other hand, medium effects both enhance the local electric field in water and, via bulk magnetization, the local magnetic field. Together these two effects partially cancel the solvation influence on the single-molecular property. We find a good agreement for the hydrogen NSOR with a recent pioneering experiment on H(2)O(l).