David C Zheng

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Infrared frequency region of 2000-2600 cm(-1) (i.e., ca. 4-5 microm in wavelength) is a well-known open spectral window for peptides and proteins. In this work, six unnatural amino acids (unAAs) were designed to have characteristic absorption bands located in this region. Key chemical groups that served as side chains in these unAAs are C[triple bond]C,(More)
A simple two-level model is developed and used to test the properties of effective interactions for performing nuclear structure calculations in truncated model spaces. It is shown that the effective manybody interactions sensitively depend on the choice of the single-particle basis and they appear to be minimized when a self-consistent HartreeFock basis is(More)
Relations between the total β+ Gamow-Teller (GT+) strength and the E2 strength are further examined. It is found that in shell-model calculations for N=Z nuclei, in which changes in deformation are induced by varying the single-particle energies, the total GT+ or GT− strength decreases monotonically with increasing values of the B(E2) from the ground state(More)
Recently no-core shell-model calculations have been performed @1,2#, in which all nucleons are active, so there are no hole states. This approach avoids the use of shell-model effective interactions involving excitations from an inert core of nucleons ~e.g., the core-polarization process!, and thereby avoids the convergence problems of the standard(More)
Dry winter eggs of Artemia salina were treated with a 30-60 mT inhomogeneous constant magnetic field for 113 h, and then carried by Chinese Satellite "8885" to its spaceflight for 8 days. Their early development rate and hatching ratio were observed on the 10th, 31st, 65th and 227th days after the accomplishment of the flight. Three main results were(More)
Large-basis shell model studies of low-lying excitations in light nuclei from He to Li have been performed with a multivalued G-matrix effective interaction, as recently suggested by Haxton et al.. Calculations were performed relative to the vacuum (“no core”) using very large, separable model spaces containing all excitations with unperturbed energies up(More)
We consider several topics concerning static magnetic dipole and electric quadrupole moments (μ and Q) as signatures of the onset of nuclear collectivity. Having previously noted that in Cr there is an abrupt change of sign in Q of yrast states with J = 10, 12, and 14 relative to lower J states, we discuss whether these states are oblate or prolate. We next(More)
It is shown that when higher-shell admixtures are included for systems with two valence particles or holes, there are effects which are quite different from those for one-valence-nucleon systems. For example, for nuclei with one valence particle or hole, there is no first-order correction for the magnetic dipole moment or the Gamow-Teller transition(More)
The Lee-Suzuki iteration method is used to include the folded diagrams in the calculation of the two-body effective interaction v (2) eff between two nucleons in a no-core model space. This effective interaction still depends upon the choice of single-particle basis utilized in the shell-model calculation. Using a harmonic-oscillator single-particle basis(More)
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