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11.
12.
Jones RM Van De Water RW Lindsey CC Hoarau C Ung T Pettus TR 《The Journal of organic chemistry》2001,66(10):3435-3441
A low-temperature method for generating o-quinone methides is described which permits facile introduction of assorted R substituents onto the aryl ring system at low temperature. The method is useful for the efficient preparation of ortho-ring-alkylated phenols. 相似文献
13.
Gábor Csiszár Tamás Ungár Márta Járó 《Applied Physics A: Materials Science & Processing》2013,111(3):897-906
Micro-structure can talk when documentation is missing. In ancient Roman or medieval periods, kings, queens, or just rich people decorated their clothes or even their horse covers richly with miniature jewels or metal threads. The origin or the fabrication techniques of these ancient threads is often unknown. Thirteen thread samples made of gold or gilt silver manufactured during the last sixteen hundred years are investigated for the micro-structure in terms of dislocation density, crystallite size, and planar defects. In a few cases, these features are compared with sub-structure of similar metallic threads prepared in modern, twentieth century workshops. The sub-structure is determined by X-ray line profile analysis, using high resolution diffractograms with negligible instrumental broadening. On the basis of the sub-structure parameters, we attempt to assess the metal-threads manufacturing procedures on samples stemming from the fourth century A.D. until now. 相似文献
14.
A nanostructured chalcogenide-metal optical fiber is proposed. This hybrid nanofiber is embedded with a periodic array of triangular-shaped deep-subwavelength metallic nanowires set up in a bowtie configuration. Our simulations show that the proposed nanostructured fiber supports a guided plasmonic mode enabling both subwavelength field confinement and extreme nonlinear light-matter interactions, much larger than a bare chalcogenide nanowire of comparable diameter. This is all achieved with less than 3% by volume of metal content. 相似文献
15.
Traditional methods of developing flight schedules generally do not take into consideration disruptions that may arise during actual operations. Potential irregularities in airline operations such as equipment failure are not adequately considered during the planning stage of a flight schedule. As such, flight schedules cannot be met as planned and their performance is compromised, which may eventually lead to huge losses in revenue for airlines. In this paper, we seek to improve the robustness of a flight schedule by re-timing its departure times. The problem is modeled as a multi-objective optimization problem, and a multi-objective genetic algorithm (MOGA) is developed to solve the problem. To evaluate flight schedules, SIMAIR 2.0, a simulation model which simulates airline operations under operational irregularities, has been employed. The simulation results indicate that we are able to develop schedules with better operation costs and on-time performance through the application of MOGA. 相似文献
16.
Cho DW Latham JA Park HJ Yoon UC Langan P Dunaway-Mariano D Mariano PS 《The Journal of organic chemistry》2011,76(8):2840-2852
New types of tetrameric lignin model compounds, which contain the common β-O-4 and β-1 structural subunits found in natural lignins, have been prepared and carbon-carbon bond fragmentation reactions of their cation radicals, formed by photochemical (9,10-dicyanoanthracene) and enzymatic (lignin peroxidase) SET-promoted methods, have been explored. The results show that cation radical intermediates generated from the tetrameric model compounds undergo highly regioselective C-C bond cleavage in their β-1 subunits. The outcomes of these processes suggest that, independent of positive charge and odd-electron distributions, cation radicals of lignins formed by SET to excited states of sensitizers or heme-iron centers in enzymes degrade selectively through bond cleavage reactions in β-1 vs β-O-4 moieties. In addition, the findings made in the enzymatic studies demonstrate that the sterically large tetrameric lignin model compounds undergo lignin peroxidase-catalyzed cleavage via a mechanism involving preliminary formation of an enzyme-substrate complex. 相似文献
17.
In the reaction with benzothiophene, t-butyl hypochlorite acts simultaneously as a smooth oxidizing agent and as a chlorinating agent since it is a source of both hypochlorous acid and chlorine. The mixture of all the products obtained imply that the reaction intermediate is the unstable benzothiophene I-oxide which was shown to be present by the stop flow technique. The chlorine formed traps the highly reactive benzothiophene 1-oxide in situ to give the observed products. 相似文献
18.
A.Y.-M. Ung 《Chemical physics letters》1975,32(1):193-196
The afterglow produced from an ozonizer discharge of nitrogen showed a well developed second positive system and some emission bands from the first negative system in the virtual absence of other N2 emissions. The NOγ system was also observed but the NOβ system could not be detected. These observations are interpreted on the assumption that N2 (A 3∑u+) and vibrationally excited N2 (X 1∑g+) are the principal energy carriers responsible for the excitation of the afterglow. 相似文献
19.
J. F. Bruandet Tsan Ung Chan M. Agard J. P. Longequeue C. Morand A. Giorni 《Zeitschrift für Physik A Hadrons and Nuclei》1976,279(1):69-77
The decay scheme of62Zn has been investigated by studying the yield functions, angular distributions and coincidence relation-ships of theγ-rays emitted in the63Cu(p, 2nγ) and60Ni(α, 2nγ) reactions. Spins up to7? were assigned to the observed states. Nuclear Reactions 60Ni(α, 2nγ)62Zn,E α=28–35 MeV and63Cu(p, 2nγ)62Zn,E p = 22–31 MeV; measuredE γ,I γ(θ),I γ(E p , andI γ,E α-γ coincidences,62Zn deduced decay scheme. Enriched target, Ge(Li) detectors. 相似文献
20.
Cho DW Fujitsuka M Sugimoto A Yoon UC Mariano PS Majima T 《The journal of physical chemistry. B》2006,110(23):11062-11068
Photoinduced electron transfer (PET) processes of 1,8-naphthalimide-linker-phenothiazine (NI-L-PTZ) dyads have been investigated using the nanosecond- and picosecond-transient absorption measurements. Two kinds of linker were introduced, i.e., polymethylene-linked dyad (NI-C8-PTZ and NI-C11-PTZ) and a poly(ethyl ether)-linked one (NI-O-PTZ). The 355 nm pulsed laser excitation of NI-C8-PTZ, NI-C11-PTZ, and NI-O-PTZ in acetonitrile produced NI radical anion (NI*-) and PTZ radical cation (PTZ*+) with the absorption bands around 420 and 520 nm, respectively, through charge transfer from PTZ to NI in the singlet excited state (NI(S1)) as well as in the triplet excited states (NI(T1)) in acetonitrile. On the other hand, the charge transfer process occurred only from NI(S1) in nonpolar solvents. The rates of charge transfer and charge recombination processes largely depended on the solvent polarity and they are affected by the length of linkers and electronic coupling through polyether linker. The PET mechanism is discussed in terms of the free energy change for the charge transfer. 相似文献