The average edge order of triangulations of 3-manifolds with boundary

Feng Luo and Richard Stong introduced the average edge order of a triangulation and showed in particular that for closed 3-manifolds being less than 4.5 implies that is on . In this paper, we establish similar results for 3-manifolds with non-empty boundary; in particular it is shown that being less than 4 implies that is on the 3-ball.

     

Photosensitized oxygenation of diaryl tellurides to telluroxides and their oxidizing properties

Photosensitized oxidation of tellurides carrying bulky aromatic substituents afforded the corresponding telluroxides which were found to react with simple alcohols to give the corresponding carbonyl compounds in excellent yields along with the starting tellurides.     

Kinetic resolution of racemic Grignard reagents by nickel-catalyzed asymmetric Grignard cross-coupling

Racemic Grignard reagents, 2-phenylpropylmagnesium chloride and 2-norbornylmagnesium chloride were kinetically resolved by asymmetric cross-coupling with vinyl bromides in the presence of chiral phosphine-nickel catalysts to give optically active coupling products (~37% ee) and carboxylic acids after carbonation with carbon dioxide.     

Preparation of Titania/PDMS Hybrid Films and the Conversion to Porous Materials

Transparent films of titania/poly(dimethylsiloxane) (PDMS) hybrids were prepared by the solvent evaporation from the precursor solution prepared by the co-hydrolysis and co-condensation of titanium tetraisopropoxide and a methoxy-functionalized PDMS. The hybrid films were flexible and had high homogeneity of the composition. The organic groups of PDMS were decomposed at 400°C in air to form porous films. Though the heated films were rather brittle compared to the as-synthesized films, they were still transparent and homogeneous. The BET surface areas of the films after the heat treatment at 400°C were over 300 m²/g, while the as-synthesized hybrid films were non porous. According to the BDDT classification, the nitrogen adsorption/desorption isotherms of the calcined films were Type I, showing that the films were microporous. The titania domains were still amorphous after the heat treatment at 400°C and transformed to anatase after the heat treatment at 1,000°C.     

Comprehensive analysis system using liquid chromatography-mass spectrometry for the biosynthetic study of peptides produced by cyanobacteria

Microcystins are hepatotoxic heptapeptides and general tumor promoters produced by several species of the genera Microcystis, Anabaena, Oscillatoria and Nostoc. They are non-ribosomally synthesized via a mixed polyketide synthase/non-ribosomal peptide synthetase system called microcystin synthetase. We have carried out the detection, isolation and structural determination of non-toxic peptides produced together with microcystins by toxic cyanobacteria, which are classified into several groups on the basis of their structures and some of these non-toxic peptides are also non-ribosomally synthesized as well as microcystins. In the present study, we tried to correlate the secondary metabolic peptides produced by the hepatotoxic cyanobacteria with the corresponding peptide synthetase genes. An analytical method using LC-electroscopy ionization MS and photodiode array detection was developed for the exhaustive screening of cyanobacterial peptides in Japanese strains and it was successfully applied to the peptide fractions extracted from these strains. The established method was advantageous over conventional ones using the usual HPLC and matrix-assisted laser desorption ionization time-of-flight MS, because more structural information could be obtained and it is easier to distinguish microcystins from other peptides using this method. Small amounts of other peptides could also be detected by this method. The established method will contribute to the investigation of the relationship between genes encoding the peptide synthetase and secondary metabolic peptides.     

Efficient solid-phase synthesis of clavulones via sequential coupling of alpha- and omega-chains

We describe an efficient solid-phase synthesis of clavulones via the sequential coupling of the alpha- and omega-chains, involving two separate carbon-carbon bond-forming steps. The tetrahydropyranyl linker survived these reaction conditions and was cleaved without decomposing the unstable cross-conjugated dienones. Our methodology has allowed us to prepare six clavulone derivatives that are varied within the alpha-chain.     

Facile method for the preparation of lyso-GM1 and lyso-GM2

This paper reports a facile method for the preparation of lyso-GM1 [Gal beta1-->3GalNAc beta1--> 4(Neu5Ac alpha2-->3)Galbeta1-->4Glc beta1-->1'-sphingosine] and lyso-GM2 [GalNAc beta1-->4(Neu5Ac alpha2-->3)Gal beta1-->4Glc beta1-->sphingosine], respectively, from GM1 [Galbeta1-->3GalNAc beta1-->4(Neu5Ac alpha2-->3)Galbeta1-->4Glc beta1-->1'-Cer] and GM2[GalNAc beta1-->4(Neu5Ac alpha2-->3)Galbeta1-->4Glc beta1-->1'-Cer], using sphingolipid ceramide deacylase and high performance anion-exchange chromatography (HPAEC). The enzymatically released lyso-GM1 and/or lyso-GM2 was effectively separated from its parent ganglioside by HPAEC using a Mono Q HR 5/5 column with an Amersham Biosciences fast protein liquid chromatography system. The yield was almost quantitative and the separation completed in approximately 3 h. This method is more convenient and effective than the conventional method using alkaline hydrolysis and silicic acid chromatography to generate and purify lyso-gangliosides.     

Allylic tantalums as highly imine-selective reagents

A practical method for the allylation of low electrophilic N-aliphatic imines was established by allylic tantalum. This is a superior methodology compared with conventional ones in terms of wide applicability to imines.     

Effect of pulverization on hydration kinetic behaviors of creatine anhydrate powders

The crystal orientation of creatine monohydrate varies significantly with tableting performance and pulverizing mechanism. Furthermore, the X-ray diffraction patterns of anhydrous forms of untreated creatine monohydrate and of pulverized creatine monohydrate exhibit different crystal orientations. However, hygroscopic forms of unpulverized creatine anhydrate and pulverized creatine anhydrate was exhibit the same diffraction peak pattern. The hygroscopicity of unpulverized and pulverized creatine anhydrate has been investigated by hydration kinetic methods using isothermal differential scanning calorimetry data. Testing of the hygroscopicity of unpulverized and pulverized creatine anhydrate at various levels of relative humidity (RH) at 25 °C revealed that the anhydrate was stable at less than 33% RH, but was transformed into the monohydrate at more than 52% RH. Hydration data of unpulverized and pulverized creatine anhydrate at 60% and 75% RH were calculated to determine hydration kinetics using various solid-state kinetic models. The hydration type of unpulverized and pulverized creatine anhydrate powder follows the zero-order mechanism (Polany–Winger equation) R1. The transition rate constant of pulverized creatine anhydrate, calculated from the slope of the straight line, was about 1.34–1.36 times higher than that of unpulverized creatine anhydrate.     

Ladderlike ferromagnetic spin coupling network on a pi-conjugated pendant polyradical

A poly(9,10-anthryleneethynylene)-based polyradical with two pendant stable phenoxyls in one anthracene skeleton was newly synthesized via polymerization of the corresponding bromoethynylanthracene monomer using a Pd(0) catalyst. The average molecular weight of the polymer reached M(n) = 5 x 10(3) and was soluble in common organic solvents. The polyradical was prepared from the corresponding hydroxyl precursor polymer and was appropriately stable at room temperature. The ESR spectrum of the corresponding monomeric radical suggested an effectively delocalized spin density distribution on the backbone anthracene. The magnetization and the static magnetic susceptibility of the polyradical were measured using a SQUID magnetometer. The large average spin quantum number (S = (5)/(2)) of the polyradical indicated that the ferromagnetic spin coupling network of the polyradical had spread throughout the pi-conjugated chain and that it was considerably insensitive to spin defects.