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541.
542.
The synthesis of slow reacting substances, leukotrienes C, D, and E, can be accomplished conveniently by a stereoselective biomimetic route. Details are provided for the conversion of 5-HPETE methyl ester 4 to leukotriene methyl ester (2) and thence to leukotrienes C and D. 相似文献
543.
Barton L. Willis 《International Journal of Theoretical Physics》1991,30(12):1655-1661
The Larmor radiation formula relates the momentum radiated toward infinity along a light cone from a single point charge to the velocity and acceleration of the particle. The formula applies only to a light cone whose apex is on the world line of the particle. This paper generalizes the Larmor formula to an arbitrary light cone. An example involving circular motion is worked. 相似文献
544.
Differential birefringence in Bragg gratings in multicore fiber under transverse stress 总被引:1,自引:0,他引:1
Silva-Lopez M Li C MacPherson WN Moore AJ Barton JS Jones JD Zhao D Zhang L Bennion I 《Optics letters》2004,29(19):2225-2227
We present experimental measurements of the peak splitting of the reflection spectra of fiber Bragg gratings as a result of birefringence induced by transverse loading of a multicore fiber. Measurements show that the splitting is a function of the applied load and the direction of the load relative to the azimuth of the fiber. A model for calculating the stress in the fiber that is due to an applied load is in good agreement with our experimental observations. 相似文献
545.
The coordination polymer Pb[B(Im)(4)](NO(3))(xH(2)O), constructed by using sodium tetrakis(imidazolyl)borate and lead(II) nitrate solutions, is a layered material with the metal centers facing the interlayer spacing. As in naturally occurring layered minerals, this compound can readily undergo anion exchange and reversible intercalation of solvent water in the solid state with retention of crystallinity. We observed changes in solvent intercalation by (207)Pb solid state NMR (SSNMR) and thermogravimetric analysis (TGA). Stoichiometric exchange of (15)N nitrate for nitrate and iodide for nitrate is monitored by (15)N and (207)Pb SSNMR, and single crystals of the iodide-exchanged material Pb[B(Im)(4)]I were isolated. While the iodide compound can be obtained through facile exchange from the nitrate parent compound, the organic anion benzoate is placed in the interlayer spacing for nitrate under self-assembly conditions and forms an alternating monolayer in Pb[B(Im)(4)](C(6)H(5)COO)(0.5H(2)O). The ion exchange versus self-assembly behavior correlates with the structural differences in the three compounds. In both Pb[B(Im)(4)]I and Pb[B(Im)(4)](C(6)H(5)COO)(0.5H(2)O), the lead sites act as Lewis acids for the iodide and benzoate, respectively. 相似文献
546.
B. Bhattacharjee P. Lemonidis W.H. Green Jr. P.I. Barton 《Mathematical Programming》2005,103(2):283-307
Optimization problems involving a finite number of decision variables and an infinite number of constraints are referred to as semi-infinite programs (SIPs). Existing numerical methods for solving nonlinear SIPs make strong assumptions on the properties of the feasible set, e.g., convexity and/or regularity, or solve a discretized approximation which only guarantees a lower bound to the true solution value of the SIP. Here, a general, deterministic algorithm for solving semi-infinite programs to guaranteed global optimality is presented. A branch-and-bound (B&B) framework is used to generate convergent sequences of upper and lower bounds on the SIP solution value. The upper-bounding problem is generated by replacing the infinite number of real-valued constraints with a finite number of constrained inclusion bounds; the lower-bounding problem is formulated as a convex relaxation of a discretized approximation to the SIP. The SIP B&B algorithm is shown to converge finitely to –optimality when the subdivision and discretization procedures used to formulate the node subproblems are known to retain certain convergence characteristics. Other than the properties assumed by globally-convergent B&B methods (for finitely-constrained NLPs), this SIP algorithm makes only one additional assumption: For every minimizer x* of the SIP there exists a sequence of Slater points xn for which (cf. Section 5.4). Numerical results for test problems in the SIP literature are presented. The exclusion test and a modified upper-bounding problem are also investigated as heuristic approaches for alleviating the computational cost of solving a nonlinear SIP to guaranteed global optimality. 相似文献
547.
Bram?J.?J.?SlagmolenEmail author Mark?Barton Conor?Mow-Lowry Glenn?de?Vine David?S.?Rabeling Jong?H.?Chow Albert?Romann Chunnong?Zhao Malcolm?B.?Gray David?E.?McClelland 《General Relativity and Gravitation》2005,37(9):1601-1608
In this paper we report on the alignment locking of an in vacuum 77 m long suspended mirror Fabry-Perot cavity. Lock was achieved
by mode-matching a 500 mW Nd:YAG NPRO onto a pre-mode cleaner, the output of which was then mode-matched to the suspended
cavity. The longitudinal locking was achieved by feeding back to the laser frequency actuator to follow the cavity resonance.
Subsequent implementation of a hybrid auto-alignment system enhanced the stability of the circulating power inside the cavity.
Preliminary results are presented. 相似文献
548.
The stack of base pairs within double helical DNA has been shown to mediate charge transport reactions. Charge transport through DNA can result in chemistry at a distance, yielding oxidative DNA damage at a site remote from the bound oxidant. Since DNA charge transport chemistry depends on coupling within the stacked base pair array, this chemistry is remarkably sensitive to sequence-dependent DNA structure and dynamics. Here, we discuss different features of DNA charge transport chemistry, including applications as well as possible biological consequences and opportunities. 相似文献
549.
Albermann C Soriano A Jiang J Vollmer H Biggins JB Barton WA Lesniak J Nikolov DB Thorson JS 《Organic letters》2003,5(6):933-936
[reaction: see text] In an effort to expand the scope of natural product in vitro glycorandomization (IVG), the substrate specificity of NovM was investigated. A test of four aglycon analogues and over 40 nucleotide sugars revealed NovM has a surprisingly stringent substrate specificity and provided only three new "unnatural" natural products. On the basis of the determined substrate specificity, an alternative to the sugar nucleotide biosynthetic dogma and a cautionary note for the general applicability of IVG are introduced. 相似文献
550.
M.A. Caprio N.V. Zamfir E.A. McCutchan R.F. Casten Z. Berant H. Amro C.J. Barton C.W. Beausang D.S. Brenner J.R. Cooper R.L. Gill G. Gürdal A.A. Hecht C. Hutter R. Krücken D.A. Meyer J.R. Novak N. Pietralla P.H. Regan J.J. Ressler 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):177-180
Lifetime measurements for the 2+
1 levels of 162Er and 162Yb were obtained in β+/ɛ decay at the Yale Moving Tape Collector by fast electronic scintillation timing of β+γ coincidences.
Received: 2 September 2002 / Accepted: 1 October 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: mark.caprio@yale.edu
Communicated by J. ?yst? 相似文献