Efficient Location for a Semi-Obnoxious Facility

This paper deals with a location model for the placement of a semi-obnoxious facility in a continuous plane with the twin objectives of maximizing the distance to the nearest inhabitant and minimizing the sum of distances to all the users (or the distance to the farthest user) in a unified manner. For special cases, this formulation includes (1) elliptic maximin and rectangular minisum criteria problem, and (2) rectangular maximin and minimax criteria problem. Polynomial-time algorithms for finding the efficient set and the tradeoff curve are presented.     

KNI-272, a highly selective and potent peptidic HIV protease inhibitor

Kynostatin {KNI-272; systematic name: 3-[3-benzyl-2-hydroxy-9-(isoquinolin-5-yl­oxy)-6-methyl­sulfanyl­methyl-5,8-dioxo-4,7-di­aza­nonanoyl]-N-tert-butyl-1,3-thia­zolane-4-carbox­amide}, a highly selective and potent HIV protease inhibitor containing allo­phenyl­norstatin [(2S,3S)-3-amino-2-hydroxy-4-phenyl­butyric acid], has been crystallized as the hydrate, C₃₃H₄₁N₅O₆S₂·0.803H₂O, from aqueous hexyl­ene glycol. The observed disorder of the phenyl group in the structure is related to the mode of hydration. The backbone conformation of the mol­ecule is twisted and the overall conformation of the free inhibitor is similar to that observed in its complex with HIV protease.     

Nonlinear optics for surface phase transitions

A general approach of second-harmonic generation (SHG) studies for surface phase transitions (PTs) is presented, with a thermodynamic classification of surface PTs and their relation to SHG parameters. The symmetry aspects of SHG near a surface PT are discussed, including issues connected with separation of surface and bulk contributions and the role of atomic and mesoscopic inhomogeneities. This approach is illustrated by applying it to two systems revealing a (near-) surface PT: single-crystalline SrTiO₃ near a bulk structural PT and single-crystalline Au in an electrochemical cell revealing an order–disorder and a reconstructive PT. Received: 15 January 2002 / Published online: 11 June 2002     

Effect of branching in base polymer on ionic conductivity in hyperbranched polymer electrolytes

Novel hyperbranched polymer, poly[bis(diethylene glycol)benzoate] capped with a 3,5-bis[(3′,6′,9′-trioxodecyl)oxy]benzoyl group (poly-Bz1a), was prepared, and its polymer electrolyte with LiN(CF₃SO₂)₂, poly-Bz1a/LiN(CF₃SO₂)₂ electrolyte, was all evaluated in thermal properties, ionic conductivity, and electrochemical stability window. The poly-Bz1a/LiN(CF₃SO₂)₂ electrolyte exhibited higher ionic conductivity compared with a polymer electrolyte based on poly[bis(diethylene glycol)benzoate] capped with an acetyl group (poly-Ac1a), and the ionic conductivity of poly-Bz1a/LiN(CF₃SO₂)₂ electrolyte was to be 7×10⁻⁴ S cm⁻¹ at 80 °C and 1×10⁻⁶ S cm⁻¹ at 30 °C, respectively. The existence of a 3,5-bis[(3′,6′,9′-trioxodecyl)oxy]benzoyl group as a branching unit present at ends in the base polymer improved significantly ionic conductivity of the hyperbranched polymer electrolytes. The polymer electrolyte exhibited the electrochemical stability window of 4.2 V at 70 °C and was stable until 300 °C.     

Transmission positron microscopes

Immediate and near-future plans for transmission positron microscopes being built at KEK, Tsukuba, Japan, are described. The characteristic feature of this project is remolding a commercial electron microscope to a positron microscope. A point source of electrons kept at a negative high voltage is changed to a point source of positrons kept at a high positive voltage. Positional resolution of transmission microscopes should be theoretically the same as electron microscopes. Positron microscopes utilizing trapping of positrons have always positional ambiguity due to the diffusion of positrons.     

Preparation of an Advanced Intermediate for the Synthesis of Stable Analogues of Guanofosfocin

The synthesis of C‐mannosyl‐guanosine 23 , an advanced intermediate for the preparation of stable analogues of guanofosfocin, is described. This convergent approach features an improved Traube‐type synthesis of a 8‐substituted guanine, followed by ribosylation. NMR Studies show that the C‐mannopyranosyl moiety of 23 adopts a distorted ¹C₄ conformation while the nucleoside is predominantly syn‐oriented.     

In-focus Fourier-domain Optical Coherence Tomography by Complex Numerical Method

We introduce a numerical in-focus Fourier-domain optical coherence tomography(in-focus FD-OCT) which can measure cross-sectional images of samples with the high lateral resolution comparable with the resolution in the focal plane in overall range of measurement. In this method, the lateral resolution is enhanced by lateral signal processing of a complex OCT image obtained with FD-OCT. Quantitative evaluation of this method and application to measurement of a porcine eyeball are presented.