Theoretical investigation of the hydride migration to coordinated carbon monoxide

SCF and Cl calculations for the hydride migration to the carbonyl ligand of the HMn(CO)₅ system are reported. A rather high barrier, obtained from     

A single-electron circuit as a discrete dynamical system

A single-electron circuit can be operated as a discrete dynamical system because it changes its internal state discontinuously because of electron tunneling. To confirm this idea, we designed a sample circuit for discrete dynamical operation and confirmed by computer simulation that the circuit successfully generated a sequence of discrete-time outputs by following a return map. The concept of discrete dynamical systems will be useful in developing new functional systems that consist of quantum devices and nanostructures.     

Spin frustration in Y(Sc)Mn2

The relaxation rate of muon polarization of Y_0.97Sc_0.03Mn₂ with a magnetic lattice composed of corner‐shared tetrahedrons shows a broad peak around 2.5 K indicating a random spin freezing at low temperatures. The substitution by nonmagnetic Al atoms for 10% Mn atoms raises the spin freezing temperature to 45 K. The present work shows clearly that due to the strong geometrical frustration, the ground state of the system is singlet tetrahedrons mixed with frozen paramagnetic tetrahedrons. This revised version was published online in July 2006 with corrections to the Cover Date.     

Low-density attack revisited

The low-density attack proposed by Lagarias and Odlyzko is a powerful algorithm against the subset sum problem. The improvement algorithm due to Coster et al. would solve almost all the problems of density <0.9408... in the asymptotical sense. On the other hand, the subset sum problem itself is known as an NP-hard problem, and a lot of efforts have been paid to establish public-key cryptosystems based on the problem. In these cryptosystems, densities of the subset sum problems should be higher than 0.9408... in order to avoid the low-density attack. For example, the Chor-Rivest cryptosystem adopted subset sum problems with relatively high densities. In this paper, we further improve the low-density attack by incorporating an idea that integral lattice points can be covered with polynomially many spheres of shorter radius and of lower dimension. As a result, the success probability of our attack can be higher than that of Coster et al.’s attack for fixed dimensions. The density bound is also improved for fixed dimensions. Moreover, we numerically show that our improved low-density attack makes the success probability higher in case of low Hamming weight solution, such as the Chor-Rivest cryptosystem, if we assume SVP oracle calls.      

Acid catalyzed reduction of nitrosobenzene by 3,5-dipyrrolidinocarbamoyl-N-benzyl-1,4-dihydropyridine as a nadh analog

Acid catalyzed reduction of substituted nitrosobenzenes to the hydroxylamines by 3,5-dipyrrolidinocarbamoyl-N-benzyl-1,4-dihydropyridine has been studied in anhydrous acetonitrile.     

High-resolution electron microscopic study of V6O13

High-resolution structure images of V₆O₁₃ were taken with a 1-MV electron microscope with a cutoff resolution of 0.14 nm. Individual V atom rows, as well as tunnels in the structure, were resolved. The effect of the electronic state on the structure image was investigated by comparing the observed image with the simulated images calculated by assuming various ionized states to the constituent atoms. The neutral-state model interpreted the observed image more satisfactorily than the ionized-state models. A modification of V₆O₁₃ was displayed as an image. In order to interpret the image, a structure model was proposed, which is orthorhombic with lattice parameters a = 1.1922, b = 1.19912, and c = 0.3680 nm and belongs to the space group Cmma. This structure is derived from the V₂O₅ structure by removing all the atoms on every third (001) oxygen atom plane and then introducing crystallographic shear $\text{1}\text{2}\text{[0}\text{1}\text{1}\text{]}$, instead of $\text{1}\text{6}\text{[10}\text{3}\text{]}$ in the case of normal V₆O₁₃.     

Optical Spatial Filter Sensor for Ground Speed

The prototype for a ground speed sensor has been designed, fabricated and evaluated. It works on the principle of optical spatial filtering and uses pulse driven light emitting diodes as a source of illumination. The sensor was tested at speeds ranging from 2 to 50 km/h, and an accuracy of 1.5 km/h was obtained with response time of 30 ms, height from ground of from 230 to 370 mm and on various road surfaces. The sensor is viewed as beneficial for use in a vehicle’s antilock braking system and will contribute to traffic safety.Presented at the International Commission of Optics Topical Meeting, Kyoto, 1994.     

Studies on sialic acids. XIII. Isolation of 3-deoxy-D-glycero-D-galacto-2-nonulopyranosonic acid (KDN) from chum salmon, Oncorhynchus keta

A method for analysis of 3-deoxy-D-glycero-D-galacto-2-nonulopyranosonic acid (KDN) by high-performance liquid chromatography (HPLC) with a strongly basic anion-exchange resin was developed. The method was applied to detect free KDN in water used to rinse of fertilized eggs of chum salmon, Oncorhynchus keta. Furthermore, KDN was isolated from the water as a fully protected derivative.