Multiaperture telecentric lens for 3D reconstruction

We present a telecentric lens that is able to gain 3D information. The proposed lens system has multiple aperture stops, which enable it to capture multidirectional parallel light rays, while a conventional telecentric lens has only one aperture stop and can capture only light rays that are perpendicular to the lens. We explain the geometry of the multiaperture telecentric system and show that correspondences fall on a line like those in a conventional stereo. As it is a single-lens sensor, we also introduce the principles of 3D reconstruction. Unlike a conventional stereo camera, the disparity of a scene point measured by the proposed lens system is linearly proportional to the depth of a scene point.     

Studying very light gravitino at the ILC

A collider signal with a stable gravitino of O(10) eV mass at the International Linear Collider (ILC) experiment is investigated. Such a light gravitino is generally predicted in the low-scale gauge mediation scenario of the supersymmetry breaking. We particularly focus on the case that the next lightest supersymmetric particle is stau, which eventually decays into a gravitino and a τ-lepton. With such a small gravitino mass, the lifetime of the stau is ¹⁰−15-¹⁰−11 s, and the produced stau decays before reaching the first layer of the inner detector of the ILC. It is shown, however, that the lifetime can be determined from the distribution of the impact parameter, which is obtained by observing charged tracks caused by decay products of the τ-lepton. This measurement also enables us to estimate the mass of the gravitino and determine the scale of the supersymmetry breaking. Based on a simulation study, we found that the lifetime can be measured when it is longer than ∼¹⁰−14 s and the stau mass is about 100 GeV.     

A reduction approach to the repeated assignment problem

We consider the repeated assignment problem (RAP), which is a K-fold repetition of the n × n linear assignment problem (LAP), with the additional requirement that no assignment can be repeated more than once. In actual applications K is typically much smaller than n. First, we derive upper and lower bounds respectively by a heuristic together with local search, and an efficient method solving the continuous relaxation. The latter also solves a Lagrangian relaxation, such that the related pegging test, to fix variables at zero or one, decomposes into K independent pegging tests to LAPs. These can be solved exactly by transforming them into all-pairs shortest path problems. Together with these procedures, we also employ a virtual pegging test and reduce RAP in size. Numerical experiments show that the reduced instances, with K ? n, can be solved exactly using standard MIP solvers.     

Total syntheses of (-)- and (+)-goniomitine

The Stille coupling reaction of 3-(benzyloxymethyl)-1-(tert-butyldiphenylsiloxy)ethyl-1-(tributylstannyl)allene with N-(tert-butoxycarbonyl)-2-iodoaniline directly produced the corresponding 2-vinylindole derivative, which was independently transformed into natural (-)-goniomitine and unnatural (+)-goniomitine via the cross-metathesis with chiral oxazolopiperidone lactams. The antiproliferative activity of the synthesized natural (-)-goniomitine in Mock and MDCK/MDR1 cells showed them to be more potent to retard cell growth than unnatural (+)-goniomitine.     

Derivatives Of α-Cyclodextrin and the Synthesis of 6-O-α-D-Glucopyranosyl-α-Cyclodextrin

Abstract

Regioselective silylation of α-cyclodextrin with tert-butyl-dimethylsilyl chloride in N, N-dimethylformamide in the presence of imidazole gave, in 75% yield, the hexakis(6-O-tert-butyldimethylsilyl) derivative 2, which was transformed into the hexakis(2,3-di-O-methyl, 6-O-methyl, 2,3-di-O-propyl, and 2,3-di-O-acetyl) derivatives. On methanesulfonylation and p-toluenesulfonylation, the hexakis(2,3-di-O-acetyl) derivative 16 afforded the hexakis(2,3-di-O-acetyl-6-O-methylsulfonyl 17 and 2,3-di-O-acetyl-6-O-p -tolylsulfonyl 18) derivatives, respectively. Nucleophilic displacement of 17 and 18 with iodide, bromide, chloride, and azide ions afforded the hexakis(6-deoxy-6-iodo 19, 6-bromo-6-deoxy, 6-chloro-6-deoxy, and 6-azido-6-deoxy) derivatives, respectively, of α-cyclodextrin dodeca-acetate. The hexakis (2, 3-di-O-acetyl-6-deoxy) derivative was prepared from 19. Selective glucosylation of 16 with 2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl bromide under catalysis by halide ion, followed by removal of protecting groups, furnished 6-O-α-D-glucopyranosyl-α-cyclodextrin.     

Selective α-D-Galactosylation of Benzyl 4,6-O-Benzyhdene-β-D-Galacto-Pyranoside with 2,3,4,6-Tetra-O-Benzyl-α-D-Galactopyranosyl Bromide Under Catalysis by Halide Ion

Abstract

Selective glycosylation of benzyl 4,6-O-benzylidene-β-D-galacto-pyranoside (1) with 1.5 mole equivalent of 2,3,4,6-tetra-O-binzyl-α-D-galactopyranosyl bromide (2) catalyzed by halide ion gave the (1→2)-α-(5) and (l→3)-α-D-linked disaccharide (7) derivatives in 22 and 40% yields, respectively. The D-galactose unit at the reducing end of 2-O-α-D-galactopyranosyl-D-galactose [11) at equilibrium in D₂O was shown By ¹³C NMR spectroscopy to exist in the pyranose and furanose forms in the ratio of ～2:1.     

Organic Polymer-Silica Gel Hybrid: A Precursor of Highly Porous Silica Gel

In this article I describe two of our discoveries. The first is the preparation of a transparent solid material composed of an organic polymer and silica gel. A novel material called a “hybrid” has successfully been prepared by the sol-gel reaction of ethyl orthosilicate in the presence of an organic polymer consisting of repeating units having an N-alkylamide group. The molecular-level dispersion of the organic polymer in the framework of silica gel has been established, which is due to the hydrogen-bond interaction between the organic polymer and silanol group of silica gel. The second discovery is the preparation of porous silica gel, which has been achieved by calcination of the organic polymer-silica gel hybrid at 600°C. Pore sizes ranging from 10 to 20 Å have been attained. A method of controlling pore size has been proposed.