Ueber das Roheisen und die Bestimmung des Kohlenstoffs in demselben

Ohne Zusammenfassung     

Ueber das gelbe und rothe Arsenikglas

Ohne Zusammenfassung     

Zur Ausmittelung des Phosphors in gerichtlichen F?llen

Ohne Zusammenfassung     

Time-resolved photoelectron spectroscopy of solvated electrons in aqueous NaI solution

Time-resolved photoelectron spectroscopy was used to study the energetics and dynamics of solvated electrons in aqueous solution. Solvated electrons are generated by ultrafast photodetachment in a 100 mM aqueous NaI solution. Initially, an ensemble of strongly bound ("cold") solvated electrons and an ensemble of weakly bound ("hot") electrons in an unequilibrated solvent environment are observed. We report an ultrafast recombination channel for the "hot" electrons with a rate of (800 fs)(-1) which is in competition with thermalization occurring with a rate of (1.1 ps)(-1). The thermalized electrons recombine with the iodide radical with a rate of (22 ps)(-1). About 35% of the thermalized electrons escape geminate recombination and form free, solvated electrons. The vertical detachment energy for the solvated electron is determined to be 3.40 eV. No indication for a surface-bound electron at lower binding energies was observed.     

Correlation between polarity parameters and dielectric properties of [Na][TOTO]--a sodium ionic liquid

The ionic liquid (IL) [Na][TOTO], with sodium as the cation and an oligoethercarboxylate as the anion, shows properties that differ significantly from conventional ionic liquids, like imidazolium salts. Its polarity, determined in the temperature range of (293-333) K from measurements of Reichardt's E value and the Kamlet-Taft parameters is extraordinarily low and matches the dielectric constant extrapolated from frequency dependent complex permittivity measurements. The dielectric spectra also reveal split dynamics with the dominating slow mode probably associated with the reorientation of -COO(-)...Na(+) ion pairs and the fast mode arising from the flexibility of the oligoethylene moieties of the anion. This assignment, supported by the derived effective dipole moments, argues against our previous hypothesis [O. Zech et al., Chem.-Eur. J., 2009, 15, 1341-1345] that salts, such as [Na][TOTO], have low melting points because of cation complexation in a pseudo crown ether-like fashion and resulting "intra-molecular" charge neutralization. The present data rule out a rigid chelate-like complex as the dominating species. Considering the present findings together with the viscosities of [TOTO](-) salts, a crosslinked structure of the ionic liquid with strong -COO(-)...Na(+) interactions and relatively weaker forces between cations and ether oxygen groups of the anions appears to be plausible.     

Siderophore-Mediated Iron Uptake Promotes Yeast–Bacterial Symbiosis

In the present study, siderophore produced by the marine yeast Aureobasidium pullulans was characterized as hydroxamate by chemical and bioassays. The hydroxamate assignment was supported by the appearance of peaks at 1,647.21?C1,625.99?cm^?1 and at 1,435.04?cm^?1 in the infrared spectrum. The purified siderophore exhibited specific growth-promoting activity under iron-limited conditions for siderophore auxotrophic probiotic bacteria. Cross-utilization of siderophore indicates a symbiotic relationship between the yeast A. pullulans and the selected probiotic bacterial strains. Statistical optimization of medium components for improved siderophore production in A. pullulans was depicted by response surface methodology. The shift in UV?CVis spectroscopy indicates the photoreactive property and subsequent oxidative cleavage of purified siderophore on exposure to sunlight.     

Effect of thermal processing on the flavonols rutin and quercetin

The current research involves the study of the thermal treatment of quercetin and rutin in an aqueous model system (cooking). These substances were heated and their degradation was followed by high-performance liquid chromatography/diode-array detection (HPLC/DAD). The influence of pH and the involvement of oxygen in the degradation were studied. HPLC/electrospray ionization multi-stage mass spectrometry (ESI-MS(n)) was used for the structural characterization of the compounds produced. The influence of the degradation of the phenolic compounds on their antioxidant properties was elucidated by a electron spin resonance (ESR) spectrometry study of the reaction samples mixed with the stabilized radical, Fremy's salt. Strong degradation of the model substances took place under weak basic and oxidative conditions. Quercetin showed the most intense degradation. Protocatechuic acid could be identified as a cleavage reaction product by analyzing its retention time and molar mass during the degradation of quercetin. The structure of a second cleavage product could be identified on the basis of ESI-MS(n) fragmentation data. Also, several structures for reaction products of oxidized quercetin are suggested. The ESR analysis showed a decrease in the antioxidant activity of the reaction samples after heat treatment in aqueous solution.