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961.
Self-starting 6.5-fs pulses from a Ti:sapphire laser 总被引:7,自引:0,他引:7
Jung ID Kärtner FX Matuschek N Sutter DH Morier-Genoud F Zhang G Keller U Scheuer V Tilsch M Tschudi T 《Optics letters》1997,22(13):1009-1011
We demonstrate self-starting 6.5-fs pulses from a Kerr-lens mode-locked Ti:sapphire laser with 200-mW average output power at a pulse repetition rate of ~86 M Hz. This is to our knowledge the shortest pulse ever generated directly from a laser. For dispersion compensation we used a prism pair in combination with double-chirped mirrors, which balances the higher-order dispersion of the prism pair and therefore flattens the average total group-delay dispersion in the laser cavity. For self-starting mode locking we used a broadband semiconductor saturable-absorber mirror. 相似文献
962.
O. Merwitz H. M. Nitzsche E. Hochhäuser 《Isotopes in environmental and health studies》2013,49(4):319-322
Abstract The dose-dependent isotope fractionation during decarboxylation (13C/12C) amplifies the radiation effect in the relatively low dose range. The fractionation of the nitrogen isotopes during deamination (15N/14N) at the dose of 17 Gy was found to be smaller than that of decarboxylation. 相似文献
963.
964.
Yuriy M. Dyukarev Bernd Fritzsche Bernd Kirstein Conrad Mädler 《Complex Analysis and Operator Theory》2010,4(4):905-951
We study two slightly different versions of truncated generalized matricial moment problems of Stieltjes type. A central topic
is the construction and investigation of distinguished solutions of both moment problems under consideration. These solutions
turn out to be nonnegative Hermitian Borel measures on the real axis which are concentrated on a finite number of points.
Our approach is mainly algebraic. It is based on the use of particular matrix polynomials constructed from a nonnegative Hermitian
block Hankel matrix. 相似文献
965.
966.
Chlorophyll‐Derived Yellow Phyllobilins of Higher Plants as Medium‐Responsive Chiral Photoswitches 下载免费PDF全文
Dr. Chengjie Li Dr. Klaus Wurst Dr. Steffen Jockusch Prof. Karl Gruber Dr. Maren Podewitz Prof. Klaus R. Liedl Prof. Bernhard Kräutler 《Angewandte Chemie (International ed. in English)》2016,55(51):15760-15765
The fall colors are signs of chlorophyll breakdown, the biological process in plants that generates phyllobilins. Most of the abundant natural phyllobilins are colorless, but yellow phyllobilins (phylloxanthobilins) also occur in fall leaves. As shown here, phylloxanthobilins are unique four‐stage photoswitches. Which switching mode is turned on is controlled by the molecular environment. In polar media, phylloxanthobilins are monomeric and undergo photoreversible Z/E isomerization, similar to that observed for bilirubin. Unlike bilirubin, however, the phylloxanthobilin Z isomers photodimerize in apolar solvents by regio‐ and stereospecific thermoreversible [2+2] cycloadditions from self‐assembled hydrogen‐bonded dimers. X‐ray analysis revealed the first stereostructure of a phylloxanthobilin and its hydrogen‐bonded self‐templating architecture, helping to rationalize its exceptional photoswitch features. The chemical behavior of phylloxanthobilins will play a seminal role in identifying biological roles of phyllobilins. 相似文献
967.
Katja Fröhlich Evgeny Legotin Frank Bärhold Atanaska Trifonova 《Journal of Solid State Electrochemistry》2017,21(12):3403-3410
The spray roasting process is recently applied for production of catalysts and single metal oxides. In our study, it was adapted for large-scale manufacturing of a more complex mixed oxide system, in particular symmetric lithium nickel manganese cobalt oxide (LiNi1/3Co1/3Mn1/3O2—NMC), which is already used as cathode material in lithium-ion batteries. An additional lithiation step was coupled with the main process in order to obtain the desired layered structure. Thermogravimetric analysis and high-temperature X-ray diffractometry built the basis for determining suitable synthesis temperature regions for the used chloride precursors and the post-treatment step. The optimized process was proven on an industrial pilot line where a setup for minimum production capacity of 12 kg h?1 was possible. The powder obtained directly after roasting had a very striking morphology compared to the final lithiated product. Hollow aggregates (≥250 μm) with overall 10.926 m2 g?1 surface area and a pore diameter of 3.396 nm were observed. Their well-faceted primary particles were converted into nanosized spheres after lithiation, building a few micrometer big high-porous agglomerates. Actual composition was verified by inductively coupled plasma atomic emission spectroscopy analysis, and the crystal structure and corresponding unit cell parameters were identified and confirmed by Rietveld fit of the derived X-ray diffraction pattern. The initial electrochemical measurements show a 149-mAh g?1discharge capacity, as determined from cyclic voltammetry. 相似文献
968.
969.
970.
Zoltán M. Balogh Katrin Fässler Ioannis D. Platis 《Journal d'Analyse Mathématique》2011,113(1):265-291
We develop a method using the modulus of curve families to study minimisation problems for the mean distortion functional
in the class of finite distortion homeomorphisms. We apply our method to prove extremality of the spiral-stretch mappings
defined on annuli in the complex plane. This generalises results of Gutlyanskiĭ and Martio [12] and Strebel [23]. 相似文献