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31.
Synthesis of oligosaccharides catalyzed by thermostable β-glucosidase fromPyrococcus furiosus 总被引:3,自引:0,他引:3
M. A. Boon J. van der Oost W. M. de Vos A. E. M. Janssen K. van ’t Riet 《Applied biochemistry and biotechnology》1998,73(2-3):269-278
Focusing on CO2 fixation, photoautotrophic cultivation of the red algaPorphyridium cruentum was investigated by means of a batch culture under a 5% CO2-enriched atmosphere. The algal growth kinetics was successfully described with a logistic model, and simulation of a continuous
culture under the optimum growth conditions (30°C, 12 klux and 1.18 g-cells/L) showed that the algal CO2-fixation activity could reach 0.66 g-CO2/(L X d). Under the same growth conditions, eicosapentaenoic acid (20:5 n-3, EPA) and arachidonic acid (20:4 n-6, ARA) yields
were similarly calculated to be 3.6 mg-EPA/(L X d) and 6.5 mg-ARA/(L X d), respectively. 相似文献
32.
J. Mullens A. Vos A. De Backer D. Franco J. Yperman L. C. Van Poucke 《Journal of Thermal Analysis and Calorimetry》1993,40(1):303-311
The 124 superconductor YBa2Cu4O8 was prepared from the oxalate precursor Y2(C2O4)3. ·4BaC2O4·8CuC2O4·xH2O at one atmosphere oxygen pressure. In O2 the precursor decomposes in one step at 300°C and more gradually (300°–600°C) in Ar. The stability of the superconductor is strongly dependent on the gas atmosphere: in O2 and in air there is no significant weight change as long as the temperature does not exceed 800°C, whereas in a 1% O2-99%N2 mixture decomposition starts at about 670°C with the formation of CuO and YBa2Cu3Ox withx<7. The reduction of YBa2Cu4O8 in a 5% H2-95% Ar mixture takes place in at least four major steps with formation of products such as Y2O3, BaO, Cu2O, Cu, BaY2O4 and Ba4Y2O7. 相似文献
33.
Michael G. Pfeffer Tanja Kowacs Dr. Maria Wächtler Dr. Julien Guthmuller Prof. Dr. Benjamin Dietzek Prof. Dr. Johannes G. Vos Prof. Dr. Sven Rau 《Angewandte Chemie (International ed. in English)》2015,54(22):6627-6631
A molecular photocatalyst consisting of a RuII photocenter, a tetrapyridophenazine bridging ligand, and a PtX2 (X=Cl or I) moiety as the catalytic center functions as a stable system for light‐driven hydrogen production. The catalytic activity of this photochemical molecular device (PMD) is significantly enhanced by exchanging the terminal chlorides at the Pt center for iodide ligands. Ultrafast transient absorption spectroscopy shows that the intramolecular photophysics are not affected by this change. Additionally, the general catalytic behavior, that is, instant hydrogen formation, a constant turnover frequency, and stability are maintained. Unlike as observed for the Pd analogue, the presence of excess halide does not affect the hydrogen generation capacity of the PMD. The highly improved catalytic efficiency is explained by an increased electron density at the Pt catalytic center, this is confirmed by DFT studies. 相似文献
34.
A Flexible Photoactive Titanium Metal–Organic Framework Based on a [TiIV3(μ3‐O)(O)2(COO)6] Cluster
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Bart Bueken Dr. Frederik Vermoortele Dr. Danny E. P. Vanpoucke Dr. Helge Reinsch Dr. Chih‐Chin Tsou Dr. Pieterjan Valvekens Dr. Trees De Baerdemaeker Prof. Dr. Rob Ameloot Prof. Dr. Christine E. A. Kirschhock Prof. Dr. Veronique Van Speybroeck Prof. Dr. James M. Mayer Prof. Dr. Dirk De Vos 《Angewandte Chemie (International ed. in English)》2015,54(47):13912-13917
The synthesis of titanium–carboxylate metal–organic frameworks (MOFs) is hampered by the high reactivity of the commonly employed alkoxide precursors. Herein, we present an innovative approach to titanium‐based MOFs by the use of titanocene dichloride to synthesize COK‐69, the first breathing Ti MOF, which is built up from trans‐1,4‐cyclohexanedicarboxylate linkers and an unprecedented [TiIV3(μ3‐O)(O)2(COO)6] cluster. The photoactive properties of COK‐69 were investigated in depth by proton‐coupled electron‐transfer experiments, which revealed that up to one TiIV center per cluster can be photoreduced to TiIII while preserving the structural integrity of the framework. The electronic structure of COK‐69 was determined by molecular modeling, and a band gap of 3.77 eV was found. 相似文献
35.
Photoactivation of silver-exchanged zeolite A 总被引:1,自引:0,他引:1
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We observed for the first time a strong angle-independent modification of spontaneous emission spectra from laser dyes in photonic crystals, made of inverse opals in titania. Comparison with spectra from such crystals with much smaller lattice spacing, for which emission is in the long wavelength limit, reveals inhibition of emission up to a factor approximately 5 over a large bandwidth of 13% of the first order Bragg resonance frequency. The center frequency and bandwidth of the inhibition agree with calculated total density of states, while the measured inhibition of vacuum fluctuations is much larger. Because of the specific location of the dye molecules, we likely probe the strongly modulated local photonic density of states. 相似文献
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40.
Directional fluorescence spectra of laser dye in opal and inverse opal photonic crystals 总被引:1,自引:0,他引:1
We have investigated the fluorescence from R6G dye molecules embedded in fcc photonic crystals with a large range of lattice parameters. Both polystyrene opals and alumina inverse opals are studied, allowing us to compare direct and inverted structures. We observe clear stop bands in the fluorescence spectra, whose center positions, widths, and depths are analyzed and compared to stop bands from reflectivity measurements. In the frequency range of first-order stop gaps, the measured stop band centers and widths agree well with theoretical predictions. The depths are interpreted in terms of the mean free path (disorder) and the Bragg attenuation length (order). We observe intriguing enhanced emission at the blue side of the stop bands, which is attributed to the escape of diffuse light from the photonic crystal (related to both order and disorder). We perform the first experiments in the range of second-order stop gaps, which is the regime where the photonic band gap is anticipated. We observe complex multiple-Bragg features that correlate favorably with reflectivity peaks. 相似文献