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991.
The in silico design, synthesis, and biological evaluation of ten potent type II dehydroquinase inhibitors are described. These compounds contain an anhydroquinate core, incorporated as a mimic of the enolate reaction intermediate. This substructure is attached by a variety of linking units to a terminal phenyl group that binds in an adjacent pocket. Inhibitors were synthesised from (-)-quinic acid using palladium-catalysed Stille and carboamidation chemistry. Several inhibitors exhibited nanomolar inhibition constants against type II dehydroquinases from Streptomyces coelicolor and Mycobacterium tuberculosis. These are among the most potent inhibitors of these enzymes reported to date. 相似文献
992.
It is shown how the transfer function from frequency noise to a Pound-Drever-Hall signal for a Fabry-Perot cavity can be used to accurately measure cavity length, cavity linewidth, mirror curvature, misalignments, laser beam shape mismatching with resonant beam shape, and cavity impedance mismatching with respect to vacuum. 相似文献
993.
We report on a single shot optical parametric chirped pulse amplifier designed to seed the Petawatt Aquitaine Laser on the Laser Integration Line facility multipetawatt high-energy laser. The scheme is based on a stretched signal pulse at 1053 nm amplified with 20% conversion efficiency by a monomode pump pulse at 527 nm. The homemade pump laser is able to deliver a single shot beam with a square flat top spatial profile and programmable temporal shape. A high-stability 150 mJ, 8 nm, and 4.5 ns stretched pulse is then obtained with an excellent quality spatially shaped beam. 相似文献
994.
We present an optical architecture for the laser optical feedback imaging (LOFI) technique that makes it possible to avoid the effect of the optical parasitic reflections introduced by the optical components located between the laser source and the studied object. These reflections damage phase and amplitude information contained in the images. This phenomenon is a leading problem that strongly limits the LOFI performance for weak feedback detection. Consequently, it is essential to be able to limit or avoid the effect of these parasitic reflections to reach the optimal LOFI performance. 相似文献
995.
Chen DC Jones SM Silva DA Olivier SS 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(5):1305-1312
Adaptive optics scanning laser ophthalmoscopes have been used to produce noninvasive views of the human retina. However, the range of aberration compensation has been limited by the choice of deformable mirror technology. We demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human eye while maintaining the quality of the retinal imagery. We verified experimentally that the use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the micro-electro-mechanical-system mirror alone and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. We also demonstrated that the large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina. 相似文献
996.
The fragmentation of natural peptides using dynamic collision-induced dissociation (DCID), a novel fragmentation method for quadrupole ion traps, is demonstrated. Using leucine enkephalin as a diagnostic molecule, the fragmentation efficiencies and energetics of DCID are compared with other methods of collisional activation in ion traps such as conventional on-resonance excitation and high-amplitude short-time excitation (HASTE). A typical fragmentation efficiency of approximately 20% is achieved for DCID, which is significantly lower than conventional CID (maximum near 80%). Tandem mass spectra of two other peptides, substance P and oxidized insulin alpha-chain, demonstrate that product ion spectra for DCID are comparable to conventional or HASTE CID. Because DCID achieves fragmentation during the standard mass acquisition scan, no extra time is necessary for on-resonance excitation or product ion collection, so analysis times are reduced by a minimum of 10-15% depending on the scanning conditions. DCID therefore offers more tandem mass spectra per second than conventional methods of collisional activation, which could be highly advantageous for bottom-up proteomics separations. 相似文献
997.
Kangying Zhu Hao Chen Jean-Philippe Masse Olivier Bouaziz Gabriel Gachet 《Acta Materialia》2013,61(16):6025-6036
Most advanced high-strength steel products contain complex phases, including ferrite, bainite and martensite, which form successively during elaboration. It is essential to understand the effect of prior ferrite transformation on the subsequent bainite and martensite transformation kinetics to achieve precise control of the final microstructure. Nevertheless, the effect of the interface between the prior formed ferrite and the residual austenite (α/γ), together with the related chemical heterogeneity at the interface, on the subsequent phase transformations has been studied only rarely, and remains unclear. This study pays particular attention to the effect of the α/γ interface and its related concentration gradients on bainite and martensite transformation. It is shown that the interface and its related concentration gradients can play a very significant role on the subsequent bainite or martensite transformation kinetics: it retards bainite transformation whereas it accelerates martensite transformation. It is revealed from microprobe wavelength-dispersive spectrometry analysis and model calculations that there are both manganese and carbon gradients in front of the α/γ interface at the end of the ferrite transformation holding. The subsequent bainite transformation kinetics is controlled by the competition between the acceleration effect of the interface boundary itself and the retardation effect of the higher alloying concentration near the interface. Martensite transformation should initiate at the pre-existing dislocations in the center of the residual austenite grains, where the C and Mn contents are the lowest. A simple martensite transformation kinetics model taking into account C heterogeneity is proposed that can describe well the martensite transformation kinetics following the prior ferrite transformation. 相似文献
998.
A.A. Fedotov S.A. Grigoriev E.K. Lyutikova P. Millet V.N. Fateev 《International Journal of Hydrogen Energy》2013
An innovative approach to the synthesis of nanostructured carbon-supported platinum electrocatalysts for application in proton-exchange membrane (PEM) electrochemical systems has been developed. Platinum nano-particles were deposited onto the carbon carrier using magnetron-ion sputtering. A special device has been developed to promote the effective stirring of the carbon carrier during catalyst deposition. Electrocatalytic powders thus obtained have been analyzed using XRD and TEM. The electrochemical performances of Pt/C based electrodes were studied in liquid electrolyte and in single-cell PEM fuel cell and water electrolyzer. Adjustment of sputtering process parameters (discharge power, sputtering time, bias voltage) led to the formation of electrocatalysts of high active surface area (up to 44 m2 g−1), high chemical purity and high electrochemical activity. A qualitative correlation between sputtering parameters and characteristics of electrocatalysts was established. 相似文献
999.
Kieran P. Somers John M. Simmie Fiona Gillespie Christine Conroy Gráinne Black Wayne K. Metcalfe Frédérique Battin-Leclerc Patricia Dirrenberger Olivier Herbinet Pierre-Alexandre Glaude Philippe Dagaut Casimir Togbé Kenji Yasunaga Ravi X. Fernandes Changyoul Lee Rupali Tripathi Henry J. Curran 《Combustion and Flame》2013
1000.
Pierre-Olivier Logerais Raouf Khelalfa Olivier Riou Jean-Félix Durastanti Anne Bouteville 《传热工程》2013,34(13):1111-1121
The heating of a silicon wafer in a rapid thermal process is studied by numerical simulation. In the model, the equations of conservation of mass and energy are solved with the finite-volume method and the determination of the solutions of the radiative transfer equation is based on the Monte-Carlo method. The results of numerical simulations, without optimization and in steady state, show a close relationship between the thermal profiles of the silicon wafer and the ones of the quartz window. By introducing a high thermal diffusivity value for the window, the homogeneity of the wafer temperature is improved by 54%. The effect of heat storage by the quartz window on the temperature profile of the silicon substrate is hence well appreciated. Finally, a selection of materials is proposed for the implementation of the high diffusivity infrared window. 相似文献