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71.
The development of robust infrared fibers is crucial for harnessing the capabilities of new mid-infrared lasers. We present a novel approach to the fabrication of chalcogenide glass fiber preforms: one-step multimaterial extrusion. The preform consists of a glass core and cladding surrounded by a built-in, thermally compatible, polymer jacket for mechanical support. Using this approach we extrude several preform structures and draw them into robust composite fibers. Furthermore, the polymer cladding allows us to produce robust tapers with submicrometer core diameter. 相似文献
72.
The synthesis of the tricyclic angular chromone structure originally assigned to aspergillitine is reported. The synthesis was achieved in 11 steps and 15% overall yield from 2,4-dihydroxypropiophenone, through the intermediacy of 2,3-dimethyl-7-hydroxychromen-4-one. Construction of the nitrogen-bearing heterocyclic ring entailed a Stille cross-coupling reaction with n-Bu(3)SnCH(2)CH=CH(2), followed by double bond isomerization, oximation of the chromone carbonyl, and a final microwave-assisted electrocyclization of the thus formed 6π-electron aza-triene system. 相似文献
73.
Uniform nonlinear approximation on an infinite interval is studied. This study was motivated by a specific nonlinear approximation problem arising in the construction of a stiff ordinary differential equation system solver. General results include characterization, uniqueness, and discretization theorems, as well as a computational algorithm for this problem. 相似文献
74.
Applied Biochemistry and Biotechnology - 相似文献
75.
Allan N. Kaufman 《Physics letters. A》1985,109(3):87-89
The concept of dissipative hamiltonian system is converted to Lorentz-covariant form, with evolution generated jointly by two scalar functionals, the lagrangian action and the global entropy. A bracket formulation yields the local covariant laws of energy-momentum conservation and of entropy production. The formalism is illustrated by a derivation of the covariant Landau kinetic equation. 相似文献
76.
R. Kaufman 《Israel Journal of Mathematics》1985,50(4):353-356
Theorem. Let S be a bounded Suslin set in the plane. Then there is a bounded linear operator T in co, whose point spectrum σ
e
(T)=S. 相似文献
77.
J. K. Brooks Kazuyuki Saitô JD Maitland Wright 《Rendiconti del Circolo Matematico di Palermo》2003,52(1):5-14
LetA be aC*-algebra with second dualA″. Let (φ
n)(n=1,...) be a sequence in the dual ofA such that limφ
n(a) exists for eacha εA. In general, this does not imply that limφ
n(x) exists for eachx εA″. But if limφ
n(p) exists whenever p is the range projection of a positive self-adjoint element of the unit ball ofA, then it is shown that limφ
n(x) does exist for eachx inA″. This is a non-commutative generalisation of a celebrated theorem of Dieudonné. A new proof of Dieudonné’s theorem, for
positive measures, is given here. The proof of the main result makes use of Dieudonné’s original theorem. 相似文献
78.
Moment type estimation of characteristics of a successively sampled finite population requires finding a solution to a pair of transcendental equations. Some global properties of two structurally distinct pairs—a symmetric and an asymmetric pair—of such equations are presented. Results of a Monte Carlo experiment designed to compare the performance of estimators computed by solving these transcendental equation pairs are reported. 相似文献
79.
80.