نتایج جستجو برای: 2s
تعداد نتایج: 6212 فیلتر نتایج به سال:
e + e − experiments producing charmonium are reviewed. It is found that the contribution of the continuum amplitude via virtual photon was neglected in almost all the experiments and the channels analyzed. It is shown that the contribution of the continuum part may affect the final results significantly in ψ(2S) and ψ(3770) decays, while the interference between continuum and resonance amplitud...
Khat (Catha edulis Forsk.) is a flowering perennial shrub cultivated for its neurostimulant properties resulting mainly from the occurrence of (S)-cathinone in young leaves. The biosynthesis of (S)-cathinone and the related phenylpropylamino alkaloids (1S,2S)-cathine and (1R,2S)-norephedrine is not well characterized in plants. We prepared a cDNA library from young khat leaves and sequenced 4,8...
We show that to each graceful labelling of a path on 2s + 1 vertices, s ≥ 2, there corresponds a current assignment on a 3-valent graph which generates at least 22s cyclic oriented triangular embeddings of a complete graph on 12s + 7 vertices. We also show that in this correspondence, two distinct graceful labellings never give isomorphic oriented embeddings. Since the number of graceful labell...
We have studied the inclusive photon spectra in Upsilon(2S) and Upsilon(3S) decays using a large statistics data sample obtained with the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates and photon energies for Upsilon(2S) --> gammachi(bJ)(1P) and Upsilon(3S) --> gammachi(bJ)(2P) (J = 0, 1, 2). We measure the rate for a rare E1 transiti...
(2S,4R)- and (2S,4S)-perfluoro-tert-butyl 4-hydroxyproline were synthesized (as Fmoc-, Boc-, and free amino acids) in 2-5 steps. The key step of each synthesis was a Mitsunobu reaction with perfluoro-tert-butanol, which incorporated a perfluoro-tert-butyl group, with nine chemically equivalent fluorines. Both amino acids were incorporated in model α-helical and polyproline helix peptides. Each ...
We show that whenever s > k(k + 1), then for any complex sequence (an)n∈Z, one has ∫ [0,1)k ∣∣∣∣ ∑ |n|6N ane(α1n+ . . .+ αkn ) ∣∣∣∣2s dα Ns−k(k+1)/2( ∑ |n|6N |an| )s . Bounds for the constant in the associated periodic Strichartz inequality from L to l of the conjectured order of magnitude follow, and likewise for the constant in the discrete Fourier restriction problem from l to L ′ , where s′...
(2S,3R)-3-Amino-2-hydroxyoctanoic acid was synthesized by Curtius rearrangement of an azide derivative of (S)-malic acid. Total syntheses of valinoctin A and its analogues were achieved by a coupling of (2S, 3R)-3-amino-2-hydroxyoctanoic acid moiety with L-valine or several other amino acids moieties. 2S configuration of 3-amino-2-hydroxyoctanoic acid moiety was found to be important for the in...
The formation and various disintegration modes of $2s$ states for muonic hydrogen deuterium atoms at kinetic energies both above below the $2s\text{\ensuremath{-}}2p$ threshold are studied. cross sections collision-induced radiative quenching, elastic scattering, Coulomb deexcitation ${({\ensuremath{\mu}}^{\ensuremath{-}}p)}_{2s}$ ${({\ensuremath{\mu}}^{\ensuremath{-}}d)}_{2s}$ in collisions wi...
Isotope shifts in dielectronic recombination spectra were studied for Li-like (A)Nd(57+) ions with A=142 and A=150. From the displacement of resonance positions energy shifts deltaE(142 150)(2s-2p(1/2))=40.2(3)(6) meV [(stat)(sys)] and deltaE(142 150)(2s-2p(3/2))=42.3(12)(20) meV of 2s-2p(j) transitions were deduced. An evaluation of these values within a full QED treatment yields a change in t...
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