Probing anisotropic interaction potentials of unsaturated hydrocarbons with He*(2 3S) metastable atom: attractive-site preference of sigma-direction in C2H2 and pi-direction in C2H4

State-resolved collision energy dependence of Penning ionization cross sections of acetylene (C2H2) and ethylene (C2H4) with He*(2 3S) metastable atoms was observed in a wide collision energy range from 20 to 350 meV. A recently developed discharge nozzle source with a liquid N2 circulator was employed for the measurements in the low-energy range from 20 to 80 meV. Based on classical trajectory calculations for the energy dependence of the partial ionization cross sections, anisotropic potential energy surfaces for the present systems were obtained by optimizing ab initio model potentials for the chemically related systems Li+C2H2 and C2H4. In the case of C2H2, the global minimum was found to be located around the H atom along the molecular axis with a well depth of 48 meV (ca. 1.1 kcal/mol). On the other hand, a dominant attractive well with a depth of 62 meV (ca. 1.4 kcal/mol) was found in the piCC electron region of C2H4. These findings were discussed in connection with orbital interactions between molecular orbitals of the target molecules and atomic orbitals of the metastable atom. It is concluded that sigma-type unoccupied molecular orbitals of C2H2 and a piCC-type highest occupied molecular orbital of C2H4 play a significant role for the attractive-site preference of sigma direction in C2H2 and pi direction in C2H4, respectively.     

BiScO3: centrosymmetric BiMnO3-type oxide

With neutron powder diffraction, electron diffraction, and second-harmonic generation, we have shown that BiScO3 has a structure closely related to that of multiferroic BiMnO3, but BiScO3 crystallizes in the centrosymmetric space group of C2/c. These results bring up a question about the origin of ferroelectricity in BiMnO3. BiScO3 may serve as a model system to understand the role of Mn3+ ions in the ferroelectricity of BiMnO3.     

Simultaneous genotyping of indels and SNPs by mass spectroscopy

Nucleotide insertion/deletion polymorphisms (indels) in ApoE gene were precisely genotyped using artificial ribonucleases and MALDI-TOF MS. The RNA fragments for MS analysis were prepared by treating RNA specimens with our artificial ribonucleases, which consist of LuCl(3) (molecular scissors) and oligonucleotides bearing two acridine groups (RNA-activator for site-selective scission). RNA scission by Lu(III) ion always occurred at the phosphodiester linkages in front of the two acridines, even when the RNA specimens involved consecutive cytidine sequences of different lengths. Thus, even complicated mixtures of these indel specimens were completely genotyped by using only one acridine-bearing oligonucleotide and by subjecting the reaction mixture to single MS measurement. Moreover, single nucleotide polymorphism (SNP) in the consecutive sequences could be genotyped simultaneously with the indels.     

Pyrinadine A, a novel pyridine alkaloid with an azoxy moiety from sponge Cribrochalina sp.

A novel cytotoxic bis-3-alkylpyridine alkaloid with an azoxy moiety, pyrinadine A (1), has been isolated from an Okinawan marine sponge Cribrochalina sp. (SS-1115), and the structure was elucidated by spectroscopic data and chemical means.     

The elementary transformation of vector bundles on regular schemes

We give a generalized definition of an elementary transformation of vector bundles on regular schemes by using Maximal Cohen-Macaulay sheaves on divisors. This definition is a natural extension of that given by Maruyama, and has a connection with that given by Sumihiro. By this elementary transformation, we can construct, up to tensoring line bundles, all vector bundles from trivial bundles on nonsingular quasi-projective varieties over an algebraically closed field. Moreover, we give an application of this theory to reflexive sheaves.

     

Double Shrinkage Estimators in the GMANOVA Model

In the GMANOVA model or equivalent growth curve model, shrinkage effects on the MLE (maximum likelihood estimator) are considered under an invariant risk matrix. We first study the fundamental structure of the problem through which we decompose the estimation problem into some conditional problems and then demonstrate some classes of double shrinkage minimax estimators which uniformly dominate the MLE in the matrix risk.     

A Method of Orthogonal Oligosaccharide Synthesis Leading to a Combinatorial Library Based on Stationary Solid‐Phase Reaction

A new, efficient synthesis of oligosaccharides, which involves solid‐phase reactions without mixing in combination with an orthogonal‐glycosylation strategy, is described. Despite a great deal of biological interest, the combinatorial chemistry of oligosaccharides is an extremely difficult subject. The problems include 1) lengthy synthetic protocols required for the synthesis and 2) the variety of glycosylation conditions necessary for individual reactions. These issues were addressed and solved by using the orthogonal‐coupling protocol and the application of a temperature gradient to provide appropriate conditions for individual reactions. Furthermore, we succeeded in carrying out solid‐phase reactions with neither mechanical mixing nor flow. In this report, the synthesis of a series of trisaccharides, namely, α/β‐L ‐Fuc‐(1→6)‐α/β‐D ‐Gal‐(1→2/3/4/6)‐α/β‐D ‐Glc‐octyl, is reported to demonstrate the eligibility of the synthetic method in combinatorial chemistry.     

Reversible and stable redox behavior of a Pt(II) bis(dithiobenzoate)-type complex attributed to rotaxane-based stabilization

A three-dimensionally insulated Pt(II) bis(dithiobenzoate) complex with a [1]rotaxane structure was synthesized using permethylated cyclodextrins. We have confirmed macrocyclic insulation is necessary to yield the Pt(II) bis(dithiobenzoate) complex with high selectivity. Furthermore, the formed Pt(II) complex showed highly stable and reversible two-step redox behavior in cyclic voltammetry due to the three-dimensional insulation.     

Exponents of 2-multiarrangements and multiplicity lattices

We introduce a concept of multiplicity lattices of 2-multiarrangements, determine the combinatorics and geometry of that lattice, and give a criterion and method to construct a basis for derivation modules effectively.