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101.
Hsieh HT Psaltis D Beyer O Maxein D von Korff Schmising C Buse K Sturman B 《Optics letters》2005,30(17):2233-2235
Spatial gratings are recorded holographically by two femtosecond pump pulses at 388 nm in lithium niobate (LiNbO3) crystals and read out by a Bragg-matched, temporally delayed probe pulse at 776 nm. We claim, to our knowledge, the first holographic pump-probe experiments with subpicosecond temporal resolution for LiNbO3. An instantaneous grating that is due mostly to the Kerr effect as well as a long-lasting grating that results mainly from the absorption caused by photoexcited carriers was observed. The Kerr coefficient of LiNbO3 for our experimental conditions, i.e., pumped and probed at different wavelengths, was approximately 1.0 x 10(-5) cm2/GW. 相似文献
102.
Chen C. Y. Liu C. M. Yeh H. C. Li W. J. Li H. T. Cheng M. J. Hsieh P. C. Wang H. M. 《Chemistry of Natural Compounds》2022,58(3):455-458
Chemistry of Natural Compounds - A new β-ionone, litulipiferic acid (12), was isolated from the leaves of Liriodendron tulipifera (Magnoliaceae). The structure of the new β-ionone was... 相似文献
103.
The synthesis and structural characterization of several new silver complexes of L (L = a bidendate ligand of pyrazole and N-heterocyclic carbene) are described. The result shows that the choice of counterions, N-substitutions of L, and reaction conditions are crucial which lead to a variety of structural motifs, including novel metallomacrocycles [Ag2(mu-L)2]2+ with or without Ag...Ag close contact, a mononuclear [AgL2]+ complex, and a [LAg(NO3)]n coordination polymer. In particular, the nonbonding Ag...Ag distance and the overall geometry of the metallomacrocycles are controllable with different N-substitutions and counterions. All these complexes have been determined by X-ray diffraction. The solid-state aggregates are retained in solution as supported by the electrospray mass spectroscopic studies. 相似文献
104.
Chen VC Chou CC Hsieh HY Perreault H Khoo KH 《Journal of mass spectrometry : JMS》2008,43(12):1649-1658
Protein phosphorylation is a type of posttranslational modification which plays an important role in cell regulation and signal transduction. Because of its biological relevance, a considerable amount of interest has been paid to the development of efficient techniques for phosphopeptide analysis. Although advances in MS control have enabled the high-throughput discovery of proteins from limited amounts of sample, automated selection of MS/MS precursor ions based on intensity alone can significantly hamper the detection of low-abundance phosphopeptides. On the basis of the observation that the introduction of a phosphate moiety does not dramatically change peptide retention time in reverse-phase chromatography, phosphopeptide specific MS/MS fragmentation attempts based on LC retention time and m/z were evaluated using a standard protein mixture, then using in vitro phosphorylated myelin basic protein. Results indicated that the majority (98%) of phosphopeptides identified eluted within a +/- 4-min window of the predicted LC elution time. While studies presented here are primarily proof of concept in nature, data suggest that the use of LC retention time prediction could be a valuable constraint for the identification of phosphopeptides within a set of off-line LC deposited sample spots. It is expected that the development of these methods will not only permit the targeted identification of protein phosphorylation sites but also allow the in-depth analysis of the dynamic events linked to the posttranslational modification. 相似文献
105.
Yi-Chih Hsieh Mark S. Andersland 《The Journal of the Operational Research Society》1995,46(6):747-752
We develop an exact closed-form expression for the steady-state availability of a repairable, N-server system in which the ith server contains n i identical, reconfigurable, breakdown-prone units. Our approach, which follows from the Markov chain balance equations and the recursive properties of Hessenberg matrix determinants, is simpler than previously proposed matrix geometric approaches, and can readily be adapted to the availability analysis of more complicated structures. We illustrate this by computing the steady-state availability of a mixed parallel-serial gracefully degrading replicated system. 相似文献
106.
This study focuses on the self-sustained oscillatory flow characteristics between two tandem circular cylinders of equal diameter
placed in a uniform inflow. The Reynolds number (Re
D
), based on the cylinder diameter, was around 1,000 and all experiments were performed in a recirculating water channel. The
streamwise distance between two tandem cylinders ranged within 1.5 ≤ X
c/D ≤ 7.0. Here X
c denotes the center-to-center distance between two tandem cylinders. For all experiments studied herein, quantitative velocity
measurements were performed using hot-film anemometer and the LDV system. The laser sheet technique was employed for qualitative
flow visualization. The wavelet transform was applied to elucidate the temporal variation and phase difference between two
spectral components of the velocity signals detected in the flow field. The remarkable finding was that when two tandem circular
cylinders were spaced at a distance within 4.5 ≤ X
c/D ≤ 5.5, two symmetrical unstable shear layers with a certain wavelength were observed to impinge onto the downstream cylinder.
The responding frequency (f
u
), measured between these two cylinders, was much higher than the natural shedding frequency behind a single isolated cylinder
at the same Re
D
. This responding frequency decreased as the distance X
c/D increased. Not until X
c/D ≥ 6.0, did it recover to the natural shedding frequency behind a single isolated cylinder. Between two tandem cylinders,
the Strouhal numbers (St
c = f
u
X
c/Uc) maintained a nearly constant value of 3, indicating the self-sustained oscillating flow characteristics with a wavelength X
c/3. Here U
c is the convection speed of the unstable shear layers between two tandem cylinders. At Re
D
= 1,000, the self-sustained oscillating characteristics between two tandem circular cylinders were proven to exhibit a sustained
flow pattern, not just a sporadic phenomenon. 相似文献
107.
Synthesis and thermotropic behaviour of liquid crystals containing tolane-based mesogenic units 总被引:3,自引:0,他引:3
Tolane-based liquid crystal materials with three different terminal groups: trifluoromethyltolanes, cyanotolanes, and nitrotolanes, and with different chain lengths of alkenyloxy groups, have been synthesized. The phase behaviour of these liquid crystal materials has been characterized by differential scanning calorimetry, optical polarized light microscopy and X-ray diffraction. The mesophase behaviour of the materials was shown to be significantly influenced by the polarity of the terminal groups. The trifluoromethyltolanes exhibit an enantiotropic smectic E mesophase and the cyanotolanes exhibit a monotropic nematic mesophase. The most polar among the three types of liquid crystal material; the nitrotolanes do not display any liquid crystalline phases, except for the homologue with an eleven methylene unit chain. 相似文献
108.
Tom H.H. Hsieh 《Tetrahedron》2009,65(16):3062-7210
Nitroalkenes have been called ‘chemical chameleons’ due to their versatility in numerous synthetic transformations. Herein, we describe the first transition metal-catalyzed transformation of conjugated nitroalkenes into indoles. Under mild reaction conditions (1 atm carbon monoxide, 110 °C), palladium catalyzes the reductive cyclization of nitroalkenes to form a putative nitrosoalkene intermediate, which then rearranges to provide 3-arylindoles in high yields. Notably, this novel C-H bond amination takes advantage of carbon monoxide as an inexpensive stoichiometric reductant and produces carbon dioxide as the major byproduct. 相似文献
109.
Theory of water waves in an elastic vessel 总被引:3,自引:0,他引:3
D. Y. Hsieh 《Acta Mechanica Sinica》2000,16(2):97-112
Recent experiments related to the Dragon Wash phenomena showed that axisymmetric capillary waves appear first from excitation,
and circumferential capillary waves appear after increase of the excitation strength. Based on this new finding, a theory
of parametric resonance is developed in detail to explain the on-set of the prominent circumferential capillary waves. Numerical
computation is also carried out and the results agree generally with the experiments. Analysis and numerical computation are
also presented to explain the generation of axisymmetric low-frequency gravity waves by the high-frequency external excitation. 相似文献
110.
The various oblique shock wave reflection patterns generated by a moving incident shock on a planar wedge using an ideal quantum
gas model are numerically studied using a novel high resolution quantum kinetic flux splitting scheme. With different incident
shock Mach numbers and wedge angles as flow parameters, four different types of reflection patterns, namely, the regular reflection,
simple Mach reflection, complex Mach reflection and the double Mach reflection as in the classical gas can be classified and
observed. Both Bose–Einstein and Fermi–Dirac gases are considered.
相似文献