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101.
102.
Lucinda R. H. Cohen Kerstin Strupat Franz Hillenkamp 《Journal of the American Society for Mass Spectrometry》1997,8(10):1046-1052
The intact noncovalent structure of the homo-oligomeric complexes of streptavidin (52 kDa), alcohol dehydrogenase (150 kDa), and beef liver catalase (240 kDa) have been observed using the matrix 2,6-dihydroxyacetophenone in an organic solvent. Intact streptavidin tetramers could also be observed with ferulic acid and other hydroxyacetophenone derivatives. Intact complexes are observed only for the first shot at a given position, which may be due to physical segregation or precipitation of the noncovalent complexes at the crystal surface. This effect is independent of the macroscopic crystal structure or the type of substrate (hydrophobic versus hydrophilic). Observation of intact complexes is not affected by addition of less than 10 mM salts or buffers, and appears to be independent of the pH stability range of the protein samples investigated. 相似文献
103.
A high-power longitudinally pumped Nd:YAG laser using direct pumping into the upper laser level is demonstrated. With an absorbed pump power of 438 W an output power of 250 W was realized, which results in an optical-to-optical efficiency of 57%. To the best of our knowledge, this is the first demonstration of a high-output power 885 nm pumped laser design. 相似文献
104.
Temperature induced refractive index changes are an important aspect in today's fiber amplifiers with high average power. For many processes, their time dependence is critical. Here, we analyze the impact of radial heat diffusion on the optical phase. We modulated the pump power in a 10?W amplifier and measured the frequency response of the optical phase. We compared the result with the calculated frequency response of the temperature in the fiber core, which shows the same characteristics. Additionally, we analyzed the influence of fiber parameters on the temperature dynamics. 相似文献
105.
Pelegrina-Bonilla G Hausmann K Liu K Sayinc H Morgner U Neumann J Kracht D 《Optics letters》2012,37(11):1844-1846
We developed a fused fiber coupler (FFC) capable of multiplexing wavelengths in the range of 795 nm and 2 μm. A simple 2D simulation model to calculate the pretaper length for matching the propagation constants in the coupling region was established. Based on the numerical data, we fabricated an asymmetric FFC consisting of two different fibers with single-mode guidance for the respective wavelength, achieving a transmission of 90% in the signal fiber for both wavelengths. In order to demonstrate the application, we integrated the FFC into a core pumped thulium-doped fiber amplifier. 相似文献
106.
We report on monotonically positively chirped pulse operation of a hybridly mode-locked thulium fiber laser. Dispersion management was realized with a small-core, high-NA fiber providing normal dispersion in the 2 μm wavelength region. The laser delivered pulses with 0.7 nJ energy at the 1927 nm center wavelength and sub-500-fs pulse duration after compression. 相似文献
107.
Dr. Kathrin Junge Konstanze Möller Bianca Wendt Shoubhik Das Dr. Dirk Gördes Prof. Dr. Kerstin Thurow Prof. Dr. Matthias Beller 《化学:亚洲杂志》2012,7(2):314-320
The combination of ZnEt2 and chiral pyridinebisoxazoline (pybox) or pyridinebisimidazoline (pybim) ligands catalyzed the asymmetric hydrosilylation of aryl, alkyl, cyclic, heterocyclic, and aliphatic ketones. Under mild conditions, high yields and good enantioselectivities were achieved. ESI measurements allowed for the characterization of the active catalyst. 相似文献
108.
Dirk Mortag Thomas Theeg Katharina Hausmann Lars Grüner-Nielsen Kim Giessmann Jespersen Uwe Morgner Dieter Wandt Dietmar Kracht Jörg Neumann 《Optics Communications》2012,285(5):706-709
An all-fiber-integrated linear chirped-pulse amplifier system generating microjoule pulse energies is reported. It is seeded by an all-fiber dissipative-soliton laser and incorporates a newly developed fiber stretcher, whose dispersive properties match that of the grating compressor. Pulse durations of 189 fs with energies of 2.2 μJ were achieved after compression. The average power was 9.8 W at the repetition rate of 4.5 MHz. 相似文献
109.
Kerstin Scheurell René König Prof. Dr. Sergey I. Troyanov Prof. Dr. Erhard Kemnitz 《无机化学与普通化学杂志》2012,638(9):1265-1273
Magnesium acetate solvates, Mg(OAc)2 · nL, and their hydrates were prepared by crystallization of Mg(OAc)2 · 4H2O or Mg(OAc)2 from different solvents (L = MeOH, EtOH, HOAc). Anhydrous Mg(OAc)2 was obtained by thermal dehydration of the tetrahydrate at 150 °C. X‐ray single crystal diffraction mostly with the use of synchrotron radiation allowed the structure determination of Mg(OAc)2(H2O)3(EtOH) ( I ), Mg(OAc)2(HOAc)2(H2O)2 ( II ), Mg3(OAc)6(MeOH)6 ( III ), Mg3(OAc)6(HOAc)2(H2O)2 · 2HOAc ( IV ), Mg(OAc)2(HOAc) · 1.8(HOAc) ( V ), Mg(OAc)2 · H2O ( VI ), [Mg3(OAc)6(EtOH)2] · 2EtOH ( VII ), and Mg(OAc)2 ( VIII ). Structural data were discussed in terms of the number of neutral O‐donor ligands per magnesium atom, coordination environment of magnesium atoms, structural functions of acetate groups, and hydrogen bonding systems. 相似文献
110.
Mónica Denham Kerstin Wendt Germán Bianchini Ana Cortés Tomàs Margalef 《Journal of computational science》2012,3(5):398-404
This work represents the first step towards a Dynamic Data-Driven Application System (DDDAS) for wildland fire prediction. Our main efforts are focused on taking advantage of the computing power provided by High Performance Computing systems and to propose computational data-driven steering strategies to overcome input data uncertainty. In doing so, prediction quality can be enhanced significantly. On the other hand, these proposals reduce the execution time of the overall prediction process in order to be of use during real-time crisis. In particular, this work describes a Dynamic Data-Driven Genetic Algorithm (DDDGA) used as steering strategy to automatically adjust highly dynamic input data values of forest fire simulators taking into account the underlying propagation model and real fire behaviour. 相似文献