874 research outputs found

    Versuche zur Regulierung des Birnenblattsaugers

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    European pear sucker causes financial penalties in many pear orchards. Honey dew exudations reduce qual-ity. Another problem is the transmission of pear decline. In years of high infestation chemical treatments are complicated. Neither cutisan- nor sugar-treatments showed an appreciable reduction of the pest in the year 2005

    Trial to control woolly aphid by earwigs

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    In years of disadvantageous atmospheric conditions natural control of woolly aphid by its parasite A. mali is insufficient in the majority of cases. In organic fruit-growing a chemical control is not possible. Settlements of earwigs showed a complete and lasting control of the pest in the year of testing, 2005. Fruitdamages were not found

    Picosecond time-resolved fluorescence of phycobiliproteins

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    The α- and β-subunits of C-phycocyanin from Mastigocladus laminosus were prepared according to revised procedures. Both subunits are isolated as dimers, which can be dissociated into monomers with detergent mixtures. The fluorescence decay kinetics are similar for the respective monomers and dimers. In no case could they be fitted by only one (α-subunit) or two exponentials (β-subunit) which are predicted by theory for samples with a unique chromophore—protein arrangement containing one and two chromophores, respectively. It is suggested that there exists a heterogeneity among the chromophores of the subunits, which may persist in the highly aggregated complexes present in cyanobacterial antennas

    Trials to control European pear sucker

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    European pear sucker causes financial penalties in many pear orchards. Honey dew exudations reduce quality. Another problem is the transmission of pear decline. In years of high infestation chemical treatments are complicated. Neither cutisan- nor sugar-treatments showed an appreciable reduction of the pest in the year 2005

    Versuch zur Regulierung der Blutlaus mittels Ohrwurmansiedlung

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    In years of disadvantageous atmospheric conditions natural control of woolly aphid by its parasite A. mali is insufficient in the majority of cases. In organic fruit-growing a chemical control is not possible. Settlements of earwigs showed a complete and lasting control of the pest in the year of testing, 2005. Fruit-damages were not found

    A General Pathway to Heterobimetallic Triple‐Decker Complexes

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    A systematic study on the reactivity of the triple-decker complex [(Cp'''Co)(2)(mu,eta(4):eta(4)-C7H8)] (A) (Cp'''=1,2,4-tritertbutyl-cyclopentadienyl) towards sandwich complexes containing cyclo-P-3, cyclo-P-4, and cyclo-P-5 ligands under mild conditions is presented. The heterobimetallic triple-decker sandwich complexes [(Cp*Fe)(Cp'''Co)(mu,eta(5):eta(4)-P-5)] (1) and [(Cp'''Co)(Cp'''Ni)(mu,eta(3):eta(3)-P-3)] (3) (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) were synthesized and fully characterized. In solution, these complexes exhibit a unique fluxional behavior, which was investigated by variable temperature NMR spectroscopy. The dynamic processes can be blocked by coordination to {W(CO)(5)} fragments, leading to the complexes [(Cp*Fe)(Cp'''Co)(mu(3),eta(5):eta(4):eta(1)-P-5){W(CO)(5)}] (2 a), [(Cp*Fe)(Cp'''Co)(mu(4),eta(5):eta(4):eta(1):eta(1)-P-5){(W(CO)(5))(2)}] (2 b), and [(Cp'''Co)(Cp'''Ni)(mu(3),eta(3):eta(2):eta(1)-P-3){W(CO)(5)}] (4), respectively. The thermolysis of 3 leads to the tetrahedrane complex [(Cp'''Ni)(2)(mu,eta(2):eta(2)-P-2)] (5). All compounds were fully characterized using single-crystal X-ray structure analysis, NMR spectroscopy, mass spectrometry, and elemental analysis

    Overview of the Temperature Response in the Mesosphere and Lower Thermosphere to Solar Activity

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    The natural variability in the terrestrial mesosphere needs to be known to correctly quantify global change. The response of the thermal structure to solar activity variations is an important factor. Some of the earlier studies highly overestimated the mesospheric solar response. Modeling of the mesospheric temperature response to solar activity has evolved in recent years, and measurement techniques as well as the amount of data have improved. Recent investigations revealed much smaller solar signatures and in some case no significant solar signal at all. However, not much effort has been made to synthesize the results available so far. This article presents an overview of the energy budget of the mesosphere and lower thermosphere (MLT) and an up-to-date status of solar response in temperature structure based on recently available observational data. An objective evaluation of the data sets is attempted and important factors of uncertainty are discussed

    Energetics of the primary electron transfer reaction revealed by ultrafast spectroscopy on modified bacterial reaction centers

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    The modification of reaction centers from Rhodobacter sphaeroides by the introduction of pheophytins instead of bacteriopheophytins leads to interesting changes in the primary photosynthetic reaction: long-living populations of the excited electronic state of the special pair P* and the bacteriochlorophyll anion B−A show up. The data allow the determination of the energetics in the reaction center. The free energy of the first intermediate P+B−A, where the electron has reached the accessory bacteriochlorophyll BA lies ≈ 450 cm−1 below the initially excited special pair P*

    General transport properties of superconducting quantum point contacts: a Green functions approach

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    We discuss the general transport properties of superconducting quantum point contacts. We show how these properties can be obtained from a microscopic model using nonequilibrium Green function techniques. For the case of a one-channel contact we analyze the response under different biasing conditions: constant applied voltage, current bias and microwave-induced transport. Current fluctuations are also analyzed with particular emphasis on thermal and shot-noise. Finally, the case of superconducting transport through a resonant level is discussed. The calculated properties show a remarkable agreement with the available experimental data from atomic-size contacts measurements. We suggest the possibility of extending this comparison to several other predictions of the theory.Comment: 10 pages, revtex, 8 figures, submitted to a special issue of Superlattices and Microstructure

    Modified bacterial reaction centers

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    Pigments of borohydride-treated reaction centers of Rhodobacter sphaeroides R 26 and Rhodopseudomonas viridis were analyzed by HPLC with polychromatic detection. In both species, pigment composition and contents were unchanged. Reaction centers from Rhodobacter sphaeroides R26 were prepared in which bacteriochlorophylls (BA,B) and bacteriopheophytins (HA,B) were exchanged with their potential borohydride products reduced at C-31. [3-Hydroxyethyl]-BChl a exchanges selectively into the BA,B pockets, and 31-OH-BPh a to the HA,B pockets. Stable reaction centers are obtained in both cases. A comparison of the absorption and circular dichroism spectra of reaction centers after exchange with 31-OH pigments, and of borohydride-modified reaction centers, reveal distinct differences. It is concluded that during borohydride reduction none of the pigments is chemically modified or extracted from the reaction centers
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