Polyacrylamides as hydrophilic selectors in non-aqueous capillary electrophoresis

Polyacrylamides (PAAms) were investigated as hydrophilic selectors in non-aqueous capillary electrophoresis (CE). Separation of 10 substituted benzoates and unsubstituted benzoate as model samples was greatly improved by the addition of PAAms in acetonitrile-CE. The migration behavior indicates that the carbonyl moiety of PAAms works as a good hydrogen-accepting site toward hydrogen-donating analytes such as 4-hydroxybenzoate anion (4OH-BA) in acetonitrile. PAAms also serve as electron-accepting agents with its amide proton interacting with the dissociated carboxyl groups of the benzoates. The ion-dipole interaction is useful to control the migration behavior of benzoates without hydrogen-donating substituents. The overall mode of the interaction is similar to that of polyethylene glycol (PEG) 20000 reported previously, but the complex formation constant of poly(N-tert.-butyl)acrylamide (PBAAm) with 40H-BA estimated here was 130-fold larger than that of PEG 20000. This would be ascribed to the strong basicity of the carbonyl oxygen atoms of PBAAm as compared with the ether oxygen atoms of PEG. Furthermore, a copolymer of (N-tert.-butyl)acrylamide-acrylamide [70:30 (in feed)] exhibited a complex formation constant of about fourfold larger toward 4OH-BA than PBAAm, most probably due to decrease in steric hindrance from the tert.-butyl groups. Adrenaline and its six precursors have been separated successfully using the PAAms.     

Non-aqueous capillary electrophoresis of p-quinone anion radicals.

The electrophoretic detection of two kinds of p-quinone anion radicals arising from the electrolysis of benzoquinone and chloranil was achieved by employing an acetonitrile medium. Sufficient dehydration of a running solution was necessary for the detection of the benzoquinone anion radical. Oxygen in the running solution also caused a serious decrease in the amount of the benzoquinone anion radical during electrophoresis. The addition of methanol as a hydrogen-donor decreased the electrophoretic mobility of the benzoquinone anion radical significantly, while that of the chloranil anion radical was little changed. This result is interpreted in terms of hydrogen-bonding interaction between the p-quinone anion radicals and methanol, reflecting the magnitude of their proton-accepting ability (benzoquinone anion radical > chloranil anion radical).     

The difference between the ordinary height and the canonical height on elliptic curves

We estimate the bounds for the difference between the ordinary height and the canonical height on elliptic curves over number fields. Our result is an improvement of the recent result of Cremona, Prickett, and Siksek [J.E. Cremona, M. Prickett, S. Siksek, Height difference bounds for elliptic curves over number fields, J. Number Theory 116 (2006) 42-68]. Our bounds are usually sharper than the other known bounds.     

Time-average holographic interferometry with a sinusoidally modulated laser diode

Laser diodes have the features of a single-mode operation and a frequency tunability. Holographic interferometry is described for investigating the vibrating amplitude and phase with a frequency-modulated laser diode. Sinusoidal wavelength change by varying laser injection current produces the sinusoidal phase modulation of relative phase difference between the reference and vibrating object paths. Holograms are made by time-average exposure of three-type recording modes with a laser diode. The phase of vibrating object is extracted from the measurements of Bessel-type fringe irradiances in three kinds of time-average holographic reconstruction. Experimental results of phase and amplitude for a vibrating cantilever object are shown.     

Synthetic Studies on Sialoglycoconjugates 95: Total Synthesis of Sulfated Glucuronyl Lactosaminyl Paraglobosides

ABSTRACT

3-O-Sulfo glucuronyl neolactohexanosyl ceramide derivatives (heptasaccharides) have been synthesized. Condensation of 2-(trimethylsilyl)ethyl 2,4,6-tri-O-benzyl-β-D-galactopyranoside (2) with 4-O-acetyl-3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl trichloroacetimidate (1) gave the desired β-glycoside 3, which was converted into 2-(trimethylsilyl)ethyl O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranosyl)-(1→3)-2,4,6-tri-O-benzyl-β-D-galactopyranoside (4) via removal of the O-acetyl and N-phthaloyl groups, followed by N-acetylation. Glycosylation of 4 with O-(methyl 4-O-acetyl-2-O-benzoyl-3-O-levulinoyl-β-D-glucopyranosyluronate)-(1→3)-2,4,6-tri-O-benzoyl-α-D-galactopyranosyl trichloroacetimidate (5) using trimethylsilyl trifluoromethanesulfonate gave the target tetrasaccharide 6, which was transformed via removal of the benzyl group, O-benzoylation, removal of the 2-(trimethylsilyl)ethyl group and imidate formation into the tetrasaccharide donor 9. Glycosylation of 2-(trimethylsilyl)ethyl O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranosyl)-(1→3)-O-(2,4,6-tri-O-benzyl-β-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (10) with the imidate donor 9 using trimethylsilyl trifluoromethanesulfonate gave the desired heptasaccharide 11, which was transformed into the heptasaccharide imidate donor 14. Glycosylation of (2S, 3R, 4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (15) with 14 gave β-glycoside 16, which was transformed into the four target compounds, via reduction of the azido group, coupling with octadecanoic acid or tetracosanoic acid, selective removal of the levulinoyl group, O-sulfation, hydrolysis of the methyl ester group and O-deacylation.     

Development in fission track-thermal ionization mass spectrometry for particle analysis of safeguards environmental samples

An improved method of fission track (FT) sample preparation was developed, in which the detector of fission track and the layer containing particles are separated, in order to apply the FT-thermal ionization mass spectrometry (TIMS) for particle analysis of safeguards environmental samples. The developed FT sample enabled us to detect the particle of interest simply by observing the fission tracks. The process of particle identification was difficult due to the discrepancy between the position of the particles and fission tracks, which were observed in the conventional FT sample. The proposed method has significantly resolved this problem.     

Gauge-Higgs unification in the left–right model

We construct a supersymmetric left–right model in four dimension with gauge-Higgs unification starting from a SU(3)_c×SU(4)_w×U(1)_B−L gauge symmetry in five dimension. The model has several interesting features, such as, the CKM mixings in the quark sector are naturally small while for the neutrino sector it is not, light neutrino masses can be generated via the seesaw mechanism in the usual way, and the model has a U(1)_R symmetry which naturally forbid dimension five proton decay operators. We also discuss the grand unification of our model in SO(12) in five dimensions.     

Toward the Exact WKB Analysis of the PII Hierarchy

We develop the exact WKB analysis of the P _II hierarchy introduced by Gordoa et al. [ 5 ] in this paper; our particular interest is in the relation between the Stokes geometry of a higher order Painlevé equation in the hierarchy and that of its underlying Lax pair. An important observation is that Stokes curves of the Painlevé equation may cross, reflecting the higher order character of the equation, and in a neighborhood of the crossing point an unexpected degeneracy of the Stokes geometry of the Lax pair may occur along a curved ray emanating from the crossing point.     

Asymmetric Synthesis of Spiroketals with Aminothiourea Catalysts

Chiral spiroketal skeletons are found as core structures in a range of bioactive compounds. These natural compounds and their analogues have attracted much attention in the field of drug discovery. However, methods for their enantioselective construction are limited, and easily available optically active spiroketals are rare. We demonstrate a novel catalytic asymmetric synthesis of spiroketal compounds that proceeds through an intramolecular hemiacetalization/oxy‐Michael addition cascade mediated by a bifunctional aminothiourea catalyst. This results in spiroketal structures through the relay formation of contiguous oxacycles, in which multipoint recognition by the catalyst through hydrogen bonding imparts high enantioselectivity. This method offers facile access to spiroketal frameworks bearing an alkyl group at the 2‐position, which are prevalent in insect pheromones. Optically active (2S,5S)‐chalcogran, a pheromone of the six‐spined spruce bark beetle, and an azide derivative could be readily synthesized from the bicyclic reaction product.     

High-speed monitoring of the crystallinity change in poly(lactic acid) during photodegradation by using a newly developed wide area NIR imaging system (Compovision)

We aimed to achieve wide area rapid monitoring of the crystallinity change in poly(lactic acid) (PLA) during photodegradation caused by ultraviolet (UV) light by using a newly developed near-infrared (NIR) camera (Compovison). Several kinds of PLA samples with different crystallinities and their blends with poly[(3)-(R)-hydroxybutyrate] were prepared. Their two-dimensional NIR spectra in the 1,000–2,350-nm region were measured by Compovision at a 5-min interval during photolysis. An intensity decrease of the band in the 1,900-1,925-nm region due to the second overtone of the C = O stretching vibration of PLA was observed during photolysis. This suggests that an anhydride carbonyl is produced during photolysis. The NIR image of the crystallinity change monitored by the band at 1,917 nm in the standard normal variate spectra clearly shows the inhomogeneity of crystal evolution. A logarithmic increase was observed for all identified areas in the PLA film; however, the time to reach the maximum crystallinity was slightly different according to the initial crystallinity of the sample. It is likely that the initial crystallinity of the sample influences the degradation speed more than the degradation amount. These imaging results have provided fundamental chemical insights into the photolytic process for PLA, and at the same time they have demonstrated that the two-dimensional spectral data obtained by Compovision are useful for process monitoring of polymers.