Determination of some dithiocarbamates by catalytic thermometric titration

The determination of dithiocarbamates by catalytic thermometric titration is described. The dithiocarbamates can be determined in the range 0.5-20 mumole with relative errors of about 5%.     

Discriminantal arrangement, 3 × 3 minors of Plücker matrix and hypersurfaces in Grassmannian Gr(3,n)

We show that points in specific degree-2 hypersurfaces in the Grassmannian $Gr(3,n)$ correspond to generic arrangements of n hyperplanes in ${\mathbb{C}}^3$ with associated discriminantal arrangement having intersections of multiplicity three in codimension two.     

Singleton Bounds for Codes over Finite Rings

We introduce the Singleton bounds for codes over a finite commutative quasi-Frobenius ring.     

Purification of enzymes by high-speed gel filtration on TSK-GEL SW columns

The purification of enzymes was investigated by high-speed gel filtration on TSK-GEL G3000SWG columns packed with porous silica gel deactivated by chemically bonded hydrophilic compounds. Crude β-galactosidase from bacterial cells and commercial urease were purified ca. 15-fold in a single gel filtration. These enzymes were eluted within an hour from the column and the recoveries of enzymatic activity were almost 100% although the operation was carried out at room temperature (22°). Samples up to 100 mg could be applied to the column without loss of separation efficiency.     

Self-regulated Ni cluster formation on the TiO2(1 1 0) terrace studied using scanning tunneling microscopy

We have studied the growth mode and morphology of Ni clusters on a TiO₂(1 1 0) surface with a wide terrace using scanning tunneling microscopy (STM) at a low coverage (less than 3 atoms nm⁻²). The Ni clusters are formed on the terrace at the low coverage of 0.2 atoms nm⁻². Their average dimensions are constant in three directions up to 1 atoms nm⁻². The Ni clusters have an oval shape with average sizes of 1.8 nm (along [0 0 1]) × 1.4 nm (along (in the [1 1 0] directions). Above the coverage of 1.0 atoms nm⁻², an increase in the cluster height occurs, retaining an almost constant lateral size. It is proposed that the interaction of the Ni cluster and the support surface regulates the Ni cluster size.     

The Japanese perspective on TIMSS

The International Association for the Evaluation of Educational Achievement (IEA) undertook three international mathematics studies: the first, FIMS, in 1976, the second, SIMS, in 1980, and the third, TIMSS, in 1995, 13-year-old Japanese students were included in these studies. The purpose of this paper is to discuss the level of mathematics achievement and attitudes toward mathematics among Japanese students and the situation of mathematics education in Japan, based on the results of TIMSS and previous studies. From our analysis of results, we can indicate the following points: although achievement in the fundamental techniques of calculation can be viewed in general as satisfactory, the attainment levels cannot be regarded as acceptable for problems which require a high degree of thinking and comprehension. And from the consequence of international comparison about interest and attitude, it became evident that a smaller fraction of Japanese students have a favorable opinion than in other countries.     

Analysis of Off-Axial Optical Systems (1)

We have established a new method of aberration analysis for off-axial optical systems which are generalized concepts of co-axial optical systems, by introducing two kinds of newly defined 4-element vectors and expanding these vectors with the help of tensor algebra. In this method, since aberration properties are represented in tensor form, we can easily formulate the aberration relations between different azimuths. We can then evaluate the azimuth dependence of aberration properties in greater detail by separating them into inherent optical properties parts, which are independent of azimuths, and the paraxial ray-tracing part, which includes the expression of the evaluation azimuth.     

Preparation and applications of novel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite nanocomposites

Novel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite (HAp) nanocomposites were prepared by the reaction of calcium nitrate tetrahydrate and phosphoric acid in the presence of the corresponding oligomer. These fluorinated oligomer/HAp composites thus obtained are nanometer size‐controlled fine particles (83–173 nm), and were found to exhibit good dispersibility in methanol, ethanol, and isopropyl alcohol. These fluorinated HAp nanocomposites were applied to the surface modification of glass and poly(methyl methacrylate) (PMMA) to exhibit good hydro‐ and oleophobic characteristics imparted by fluorine on their surface. In addition, the surface structural changes of the modified polyethylene terephtalate and PMMA films treated with these fluorinated nanocomposites before and after soaking in a simulated body fluid (SBF) were analyzed by using SEM, XRD, and EDX to observe the formation of spherical HAp deposits on the surface. Copyright © 2009 John Wiley & Sons, Ltd.