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81.
S.Y. Frankie Mak Gary C.H. Chiang James E.P. Davidson John E. Davies Andrew Ayscough Gilles Pain Jonathan W. Burton Andrew B. Holmes 《Tetrahedron: Asymmetry》2009,20(6-8):921-944
The enantioselective synthesis of a number of simplified analogues of the cytotoxic natural product eleutherobin is reported. 相似文献
82.
Rishav Choudhary Julian J. Girard Sean Clees Sarah E. Johnson Jiankun Shao David F. Davidson Ronald K. Hanson Allen A. Aradi 《Proceedings of the Combustion Institute》2021,38(1):957-965
We report the first shock tube measurements of formaldehyde (CH2O) during the first stage ignition of n-heptane, 2-methylhexane and 3,3-dimethylpentane, in highly diluted fuel/oxygen mixtures in the pressure range of 7–10 atm and temperature range of 700–880 K. Combined time histories of all carbonyl (–C = O) species, CO and fuel were also measured simultaneously in an effort to study the impact of fuel structure on the concentration and the rate of evolution of first stage ignition products. Of the three isomers studied in this work, n-heptane was found to be the fastest, while 3,3-dimethylpentane was found to be the slowest. The differences in the time scale of formation, and plateau concentration of the intermediates between the isomers across the entire range of test conditions suggests a strong dependency of the measured time histories to fuel structure. These species therefore act as markers of the Negative Temperature Coefficient (NTC) behavior of fuels and can be used as targets for developing semi-empirical, hybrid chemistry models of complex, multi-component petroleum derived gasoline and jet fuels. The time histories reported in this work should prove very useful in the refinement of detailed kinetic models of n-heptane, and development of rate rules for branched alkane isomers. 相似文献
83.
An integral equation formulation for buoyancy-driven convection problems is developed and illustrated. Buoyancy-driven convection in a bounded cylindrical geometry with a free surface is studied for a range of aspect ratios and Nusselt numbers. The critical Rayleigh number, the nature of the cellular motion, and the heat transfer enhancement are computed using linear theory. Green's functions are used to convert the linear problem into linear Fredholm integral equations. Theorems are proved which establish the properties of the eigenvalues and eigenfunctions of the linear integral operator which appears in these equations. 相似文献
84.
It is known that the exact density functional must give ground-state energies that are piecewise linear as a function of electron number. In this work we prove that this is also true for the lowest-energy excited states of different spin or spatial symmetry. This has three important consequences for chemical applications: the ground state of a molecule must correspond to the state with the maximum highest-occupied-molecular-orbital energy, minimum lowest-unoccupied-molecular-orbital energy, and maximum chemical hardness. The beryllium, carbon, and vanadium atoms, as well as the CH(2) and C(3)H(3) molecules are considered as illustrative examples. Our result also directly and rigorously connects the ionization potential and electron affinity to the stability of spin states. 相似文献
85.
Constantin D Davidson P Freyssingeas É Madsen A 《The Journal of chemical physics》2010,133(22):224902
We used x-ray photon correlation spectroscopy to study the dynamics in the lamellar phase of a platelet suspension as a function of the particle concentration. We measured the collective diffusion coefficient along the director of the phase, over length scales down to the interparticle distance, and quantified the hydrodynamic interaction between the particles. This interaction sets in with increasing concentration and can be described qualitatively by a simplified model. No change in the microscopic structure or dynamics is observed at the transition between the fluid and the gel-like lamellar phases. 相似文献
86.
Anuj R. Shah Jennifer Davidson Matthew E. Monroe Anoop M. Mayampurath William F. Danielson Yan Shi Aaron C. Robinson Brian H. Clowers Mikhail E. Belov Gordon A. Anderson Richard D. Smith 《Journal of the American Society for Mass Spectrometry》2010,21(10):1784-1788
The diverse range of mass spectrometry (MS) instrumentation along with corresponding proprietary and nonproprietary data formats has generated a proteomics community driven call for a standardized format to facilitate management, processing, storing, visualization, and exchange of both experimental and processed data. To date, significant efforts have been extended towards standardizing XML-based formats for mass spectrometry data representation, despite the recognized inefficiencies associated with storing large numeric datasets in XML. The proteomics community has periodically entertained alternate strategies for data exchange, e.g., using a common application programming interface or a database-derived format. However, these efforts have yet to gain significant attention, mostly because they have not demonstrated significant performance benefits over existing standards, but also due to issues such as extensibility to multidimensional separation systems, robustness of operation, and incomplete or mismatched vocabulary. Here, we describe a format based on standard database principles that offers multiple benefits over existing formats in terms of storage size, ease of processing, data retrieval times, and extensibility to accommodate multidimensional separation systems. 相似文献
87.
Nixon M Friedman M Ronen E Friesem AA Davidson N Kanter I 《Physical review letters》2011,106(22):223901
We experimentally investigate the phase dynamics of laser networks with homogenous time-delayed mutual coupling and establish the fundamental rules that govern their state of synchronization. We identified a specific substructure that imposes its synchronization state on the entire network and show that for any coupling configuration the network forms at most two synchronized clusters. Our results indicate that the synchronization state of the network is a nonlocal phenomenon and cannot be deduced by decomposing the network into smaller substructures, each with its individual synchronization state. 相似文献
88.
James Davidson 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2014,65(4):757-766
The solutions of the discrete Safronov–Dubovski coagulation equation are investigated. We prove global existence for a class of unbounded coagulation kernels. We also show that for sub-linear unbounded kernels, the mass conservation law holds. Finally, we show that for bounded kernels, this equation has a unique global solution that is continuously dependent on the initial data. 相似文献
89.
Adiabatic focusing of cold atoms in a blue-detuned laser standing wave is analyzed. It is shown that using repulsive light
forces that push atoms towards dark regions and thus minimizes heating, cold atoms can be adiabatically compressed by more
than an order of magnitude to yield background-free sub-10-nm (rms) spots. The optimal parameters for the atomic lens and
the maximal compression ratio are predicted using an analytic model and found to be in agreement with the exact results of
our Monte Carlo simulations. A combined adiabatic-coherent scheme is proposed and shown to yield 8.8 nm spot size even for
a thermal atomic beam.
Received: 1 October 1999 / Revised version: 13 December 1999 / Published online: 5 April 2000 相似文献
90.
F. Sima P. Davidson E. Pauthe O. Gallet K. Anselme I. N. Mihailescu 《Applied Physics A: Materials Science & Processing》2011,105(3):611-617
We report on matrix-assisted pulsed laser evaporation (MAPLE) transfer of intact and functional protein molecules from a cryogenic
aliquot obtained by freezing a protein-saline buffer solution. Vitronectin (Vn), an extracellular matrix protein with distinctive
active domains for cell attachment and signalization, was expelled from frozen targets by KrF* excimer laser irradiation,
and then immobilized on substrates. Particulates surrounded by a dense matrix were observed by optical, profilometry and AFM
studies. The composition preservation of MAPLE-deposited protein films versus drop-cast films was demonstrated by FTIR and
immunostaining studies. The stability and integrity of Vn after transfer was shown by their interaction with human osteoprogenitor
cells in which actin filaments stretched across the entire cell area and clear focal points with surface were formed. The
absence of detectable degradation of protein structure after MAPLE immobilization could provide benefits to surface functionalization
for biomedical applications. 相似文献