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Effect of supplementary manganese on the sporulation of Bacillus endospores analysed by Raman spectroscopy

It is a common practice in microbiology to induce and accelerate sporulation of spore‐forming bacteria by adding small amounts of divalent manganese to the cultivation medium. By micro‐Raman spectroscopy the effect of supplementary divalent manganese during the growth and sporulation of Bacillus spp. bacteria was studied. The spectral alterations in the Raman spectra of single endospores due to this cultivation parameter comprised slight alterations of the bands attributed to intracellular, abundantly present calcium dipicolinate (CaDPA). Those signals suffered a loss of intensity or partial band broadening because of the appearance of new weak signals next to them. Exclusively in Raman spectra of single B. sphaericuss endospores, the band at 1485 cm⁻¹ vanished. The theoretical spectra of CaDPA and manganese dipicolinate (MnDPA) were calculated and compared with the experimental spectra to prove the hypothesis that, while the overall intracellular DPA content decreased, an intracellular assembly of MnDPA in the endospores might also occur. Band shifts of the COO⁻ vibrations in the salt's spectra as well as in the endospore's spectra, and the decrease of the two CaDPA bands, confirmed this proposal. The appearance of the 1030 cm⁻¹ band in all Bacillus spectra as well as the disappearance of the 1485 cm⁻¹ band in the B. sphaericus spectra still needs to be clarified. With the help of two multivariate chemometric methods, these spectral alterations allowed discrimination between single endospores of different Bacillus strains cultivated on normal nutrient agar (NA) and those grown on NA with MnSO₄ · xH₂O addition. With these investigations, a possible strategy is shown to trace back the cultivation environment of matured single endospores. Utilizing the joint concept of micro‐Raman spectroscopy and chemometric analysis, the differentiation between natively grown endospores and those cultivated in a laboratory with the help of manganous salts as a common sporulation accelerator seems accomplishable. Copyright © 2009 John Wiley & Sons, Ltd.     

Electron spin resonance of Gd in intermetallic compounds with CsCl structure

The g-shift and the thermal broadening of the ESR linewidth of Gd doped YRh and ScM (M = Ru, Rh, Pd, Ag, Cu) are reported. The results seem to be influenced by non s-band conduction electrons.     

Cu-EPR in YBa2Cu3O6+δ single crystals

We report on the observation of Cu-EPR signals in single crystalline material of YBa₂Cu₃O₆₊ in the narrow oxygen concentration range 0.7<<0.9 and for temperatures 80 K<T<200 K. We provide evidence that the signal results from Cu²⁺ ions located in Cu(1)OCu(1) chain fragments.     

Correlation of π-conjugated oligomer structure with film morphology and organic solar cell performance

The novel methyl-substituted dicyanovinyl-capped quinquethiophenes 1-3 led to highly efficient organic solar cells with power conversion efficiencies of 4.8-6.9%. X-ray analysis of single crystals and evaporated neat and blend films gave insights into the packing and morphological behavior of the novel compounds that rationalized their improved photovoltaic performance.     

Noise suppression properties of an interferometer-based regenerator for differential phase-shift keying data

We studied the amplitude and phase noise suppression properties of an all-optical regenerator for differential phase-shift keying data. A detailed analytical investigation is performed and compared with numerical simulations for different working points. The results show that both amplitude and phase can be regenerated. However, simultaneous amplitude and phase noise suppression is possible only if the phase degradation is stronger than the amplitude degradation, for instance, due to nonlinear phase noise.     

Analysis of composition and growth mechanisms of oxide scales on high temperature alloys by SNMS,SIMS, and RBS

Composition and growth phenomena of alumina scales on a conventional wrought alloy Fe-20Cr-5Al and an yttria containing ODS alloy with the same base composition were investigated. The alloys were oxidized in a twostage oxidation process at 1000 °C in air and air containing¹⁸O-tracer. By using secondary neutrals and secondary ion mass spectrometry in combination with RBS, the in-depth concentration of main and minor alloying elements as well as the oxygen isotope distribution in the alumina scale could be determined. It is shown, that the difficulties in deriving the exact growth processes of the scales from the oxygen tracer profiles can be overcome by using the time dependance of the iron and chromium distribution in the alumina. From these results it could be derived that growth of the oxide scales formed on the ODS and the conventional alloy mainly differ in the relative contribution of aluminium diffusion. The mechanisms which lead to these differences in scale growth phenomena will be discussed.     

Surface analytical investigations on the oxidation behaviour of TiAl-base intermetallics

Summary The oxidation behaviour of TiAl-base intermetallics has been investigated at 800°C in air. The main emphasis was placed on the mechanism by which niobium additions decrease the oxidation rate of titanium aluminides. For this purpose specimens of Ti50Al and Ti45Al10Nb were oxidized in a two-stage oxidation technique using an ¹⁸O-tracer. The scale formed during this oxidation process was analyzed by SNMS. It was found that niobium is mainly incorporated in the titanium dioxide and the nitride scale which forms beneath the initially formed alumina layer. The effect of this behaviour of the niobium on the oxide scale growth rates is discussed.     

Superconductivity of hydrides Ti3SbHx

The effect of interstitially dissolved hydrogen on the transition temperature T_c of superconductivity has been investigated in cubic A-15 type (Cr₃Si type) hydrides Ti₃SbH_x, 0 ? x ? 2. The transition temperature T_c decreases with increasing hydrogen content x from 5.6 K in Ti₃Sb to 1.0 K in Ti₃SbH_1.0.