High performance of Rh(Phebox) catalysts in asymmetric reductive aldol reaction: high anti-selectivity

Chiral rhodium(bisoxazolinylphenyl) complexes (1 mol %) efficiently catalyze the asymmetric reductive aldol reaction of aldehydes and alpha,beta-unsaturated esters at 50 degrees C for ca. 0.5-1.0 h with several hydrosilanes to give the corresponding beta-hydroxypropionates with extremely high anti-selectivity (up to 98%) and enantioselectivity (up to 96% ee). The stereochemical outcome is likely due to a chairlike cyclic transition state involving rhodium-(E)-enolate.     

Radiation-induced cationic dimerization and polymerization of styrene in methylene chloride solution. I

Radiation-induced polymerization of styrene in methylene chloride solution or bulk system was investigated to explain the initiation mechanism of cationic polymerization. It was found that high energy radiation produces polymers and dimers. The main dimers were identified as trans-1,2-diphenylcyclobutane, 1-phenyl-1,2,3,4-tetrahydronaphthalene, and 1-phenyl-1,2-dihydronaphthalene. The dimerization procedure was cationic in a pattern similar to that obtained in photoexcited EDA systems. It was shown clearly by product analysis that the bonded dimer cation radical intermediate, which was assumed to be an initiating species of the cationic polymerization, was produced in a radiation-induced polymerization system. The observed polymerization was composed of two types; cationic and radical, the latter initiated by radical species.     

Study of electronic X-rays emitted from pionic and muonic atoms

The electronic X-ray energies of muonic atoms were precisely measured. The atomic number (Z) dependence of the energy difference between electronic X-rays of muonic atoms and Z-1 atoms (energy shift) was systematically investigated. The energy shifts in the low-Z region were compared with those of the high-Z region that had been obtained experimentally and theoretically in previous work. An obvious difference between these two regions was found in the atomic-number dependence of the energy shift. We also compared the energy shifts of muonic atoms with those of pionic atoms.     

ISOLATION OF BLEPHARISMIN-BINDING 200 kDa PROTEIN RESPONSIBLE FOR BEHAVIOR IN Blepharisma

Abstract— The ciliated protozoan, Blepharisma, shows an avoidance reaction (step-up photophobic response) in response to light stimulation. A profile of a gel-permeation of a crude detergent-solubilized sample of the cells resulted in several red-colored fractions. Among these blepharismin-containing fractions, the fractions III-V did not contain amino acids. The peak of fraction II monitored by 580 nm absorbance was much smaller. A prominent peak appeared in fraction I, which contained a large amount of amino acids. The absorption spectrum of fraction I was well fitted to the action spectrum of the step-up photophobic response, although free pigment (blepharismin) also fitted. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of this fraction resulted in a thicker band corresponding to molecular mass of 200 kDa. These results suggest that the 200 kDa chromoprotein (blepharismin-protein complex) is responsible for the step-up photophobic response in Blepharisma. The absorption spectrum of free chromophore dissociated from the chromophore-protein complex was identical to free red pigment termed blepharismin. The absorption spectrum of the other fractions agreed with that of thin-layer chromatography-purified red pigment, indicating that the pigments contained in these fractions are free pigment dissociated from the chromophore-protein complex.     

Y-ligation: An efficient method for ligating single-stranded DNAs and RNAs with T4 RNA ligase

Very efficient ligation ofoligodeoxyribonucleotides was attained through asimple molecular construct, which is composed of onestem and two branches (Y-shape), with use of T4 RNAligase. Single-stranded DNAs (naturally, RNAs also) ofmore than 100 nucleotides (even 800 nts) wereconsiderably ligated, approximately as theoreticallyexpected. Owing to the molecular construct adopted,such a tiny amount of ligation products could beamplified to a sufficient amount by PCR and thenrecovered as single-stranded DNAs. This advantage ofbeing amplifiable is shown to be useful for bothcombinatorial chemistry and evolutionary molecularengineering, which deal with a pool of diversity molecules.     

Performance Check of Vegetation Fluorescence Imaging Lidar through In Vivo and Remote Estimation of Chlorophyll Concentration Inside Plant Leaves

Laser-induced fluorescence imaging lidar was developed for in vivo plant/vegetation monitoring. Fluorescences of poplar tree leaves growing naturally at a distance of 60 m from the lidar were successfully detected as two spectral images at wavelengths of 685 nm and 740 nm. By comparing chlorophyll concentration quantified with high performance liquid chromatography, it was confirmed that the intensity ratio of the two wavelengths was converted into the chlorophyll concentration inside the leaves. The intensity ratio of the images reflected the status of the poplar tree in the process of senescence so well that it was possible to assess the living status of the tree as a numerical value. The performance characteristics and the potential of the laser-induced fluorescence imaging lidar for monitoring the physiological activities of plants and vegetation are described.     

Thermal stability of ion-exchange Nafion N117CS membranes

The effect of exchanged ions on the thermal stability of Nafion N117CS membranes was investigated by X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and ion exchange capacity determinations. The ion exchange of alkaline metal ions was effective in improving the thermal stability of the Nafion N117CS membrane. Findings reveal that when Nafion was exchanged for cations with a larger ionic radius, the membrane attained superior thermal stability. On the other hand, we confirmed that the Na-exchange Nafion N117CS membrane possessed a distinctive degree of thermal stability among the alkaline ion-exchange Nafions, although the order of ionic radii is K > Na > Li. Thermal stability improved the most when the Nafion membrane was exchanged for alkaline ions, followed by divalent ions, then trivalent ions. As for the Nafion membrane when it was exchanged for divalent ions or trivalent ions, Nafion following the ion exchange had a thermal stability proportional to an increase in the ionic radius of the cation. This stability may be explained by the reduction of water content and a greater interaction between the sulfonate groups and the cations with larger ionic radii. Since the Al cations acted as a Lewis acid center, the decomposition of the ether bonds of the perfluoroalkylether pendant-chains of the Nafion membrane was observed for the Nafion N117CS membrane that had been exchanged for Al ions. The activation of molecular mobility in Nafion was observed between the decomposition stages of the loss of water and the loss of sulfonic groups. The temperature of activation of cation-exchange Nafion became much higher than that of Nafion in an acid form.     

A Lower Bound for Fundamental Solutions of the Heat Convection Equations

This paper studies the heat convection equations when the convection term has some singularities at time zero. We shall establish the pointwise estimates for fundamental solutions from below by the Gaussian-like functions. As an application, we prove the existence and uniqueness of the mild solutions of the equations.     

LR Tests for Random-Coefficient Covariance Structures in an Extended Growth Curve Model

This paper is concerned with an extended growth curve model with two within-individual design matrices which are hierarchically related. For the model some random-coefficient covariance structures are reduced. LR tests for testing the adequacy of each of these random-coefficient structures and their asymptotic null distributions are derived.     

(2,2′‐Biquinoline‐κ2N,N′)dichloropalladium(II), ‐copper(II) and ‐zinc(II)

In the three title complexes, namely (2,2′‐biquinoline‐κ²N,N′)dichloro­palladium(II), [PdCl₂(C₁₈H₁₂N₂)], (I), and the corresponding copper(II), [CuCl₂(C₁₈H₁₂N₂)], (II), and zinc(II) complexes, [ZnCl₂(C₁₈H₁₂N₂)], (III), each metal atom is four‐coordinate and bonded by two N atoms of a 2,2′‐biquinoline molecule and two Cl atoms. The Pd^II atom has a distorted cis‐square‐planar coordination geometry, whereas the Cu^II and Zn^II atoms both have a distorted tetra­hedral geometry. The dihedral angles between the N—M—N and Cl—M—Cl planes are 14.53 (13), 65.42 (15) and 85.19 (9)° for (I), (II) and (III), respectively. The structure of (II) has twofold imposed symmetry.