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Abstract— C18 formate ester (5) [2-(6-methyl-8-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3E,5E,7E-octatrienyl formate], a highly reactive analog of retinal, was synthesized and its interaction with bacterioopsin studied. The formate ester, in the absence of purple or bleached membrane, undergoes very rapid reaction (tl/2 = 0.9 min) in neutral buffer but with membrane present it diffuses more rapidly into the membrane where it reacts slowly. Incorporation of 5 in the membrane results in a 38 nm (3900 cm-1 ) red shift which remains after reconstitution with retinal. Similar experiments with the corresponding C18 alcohol (4) results in a red shift, but this absorption blue shifts upon reconstitution with retinal. Washing the formate ester-treated membrane with bovine serum albumin or the corresponding lyophilized preparation with hexane, treatments that remove retinal oxime, fails to remove the UV-visible absorption, suggesting that a covalent bond between the C18 moiety and a nucleophilic group of the protein has probably formed. 相似文献
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Stanley Gudder 《Foundations of Physics》1996,26(6):813-822
A D-algebra is a generalization of a D-poset in which a partial order is not assumed. However, if a D-algebra is equipped with a natural partial order, then it becomes a D-poset. It is shown that D-algebras and effect algebras are equivalent algebraic structures. This places the partial operation for a D-algebra on an equal footing with the partial operation for an effect algebra. An axiomatic structure called an effect stale-space is introduced. Such spaces provide an operational interpretation for the partial operations and . Finally, a relationship between effect-state spaces and torsion free interval effect algebras is demonstrated. 相似文献
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A beam of relativistic antihydrogen atoms — the bound state (
e+) — can be created by circulating the beam of an antiproton storage ring through an internal gas target. An antiproton which
passes through the Coulomb field of a nucleus will create e+e− pairs, and antihydrogen will form when a positron is created in a bound instead of continuum state about the antiproton.
The cross section for this process is roughly 3Z
2 pb for antiproton momenta about 6 GeV/c. A sample of 600 antihydrogen atoms in a low-emittance, neutral beam will be made in 1995 as an accidental byproduct of Fermilab
experiment E760. We describe a simple experiment, Fermilab Proposal P862, which can detect this beam, and outline how a sample
of a few-104 atoms can be used to measure the antihydrogen Lamb shift to 1 %.
Work supported in part by Department of Energy contract DE-AC03-76SF00515 (SLAC).
Work supported by Fondo Nacional de Investigación Científica y Tecnológica, Chile. 相似文献
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