Biomedical subjects
Publications and source records attributed to MS Lee.
[structure: see text] A facile synthesis of the novel conformationally restricted reverse turn mimetic is described. The key features are the preparation of the alpha-keto amide and tandem bicyclic ring formation.
Polarized atomic orbitals (PAO's) are molecule-adapted minimal basis functions that are variationally obtained as an atom-blocked transformation from a conventional extended basis set, as a Hartree-Fock calculation is performed in the PAO basis. This approximation yields a higher energy than a HF calculation performed in the extended basis, although the two results converge to the same limit as the extended basis approaches completeness on each atom. To test the rate of convergence, PAO-HF calculations were performed using cc-pVXZ and aug-cc-pVXZ basis sets for the water monomer and dimer, and six substituted ethylenes. The results show that the quality of PAO calculations converges smoothly with X. The use of augmented functions is recommended. To correct a PAO-HF calculation for residual deficiencies, a noniterative second order correction is introduced. This correction corresponds to an energy-weighted steepest descent step, and substantially improves the quality of PAO energies.
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Blazed-binary optical elements with only binary ridges or pillars are diffractive components that mimic standard blazed-echelette diffractive elements. We report on the behavior of one-dimensional blazed-binary optical elements with local periods much larger than the wavelength. For this purpose, an approximate model based on both scalar and electromagnetic theory is proposed. The model is tested against electromagnetic-theory computational results obtained for one-dimensional blazed-binary gratings with large periods. An excellent agreement is obtained, showing that the model is able to predict quantitatively the wavelength and the incidence-angle dependences of the diffraction efficiency of blazed-binary structures.
Permeability coefficients P of KCl through porous cellulose triacetate (CTA) membranes were measured as a function of the water volume fraction V(W) and diffusion coefficients D were determined using solubility parameters K and a membrane thickness d from the relationship of P = KD/d. D increased with an increase in V(W). D especially increases abruptly around V(W) = 0.5, which corresponds to 2% triethylene glycol (TEG) content. The percolation theory was applied to the experimental results under the conditions D(A) = D (V(W) = 1) = 1.8 x 10(-5) cm(2) s(-1), D(B) = D(V(W) = 0) = 1.8 x 10(-8) cm(2) s(-1), coordination number (Z) = 2.5, 3, 3.5, and 4, and packing fraction f = 1.0. A good fit was obtained at Z = 3.5 because the experimental and calculated results also shifted at the same V(W) below V(W) = 0.5. It is suggested that a phase inversion, that is, change of a discontinuous water phase to a continuous water phase, occurs around V(W) = 0.5. Above V(W) = 0.5, the experimental results agree well with the calculated line for Z = 3 or Z = 2.5 which means that the coordination numbers decrease with an increase in water content. It is thought that V(W) is overestimated because it is hard to completely wipe off the excess water quickly from the membrane surface. Z = 3.5 means that a pore can connect in 3.5 directions. Copyright 1999 Academic Press.
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