Selective synthesis of 1,4,5-trisubstituted imidazoles from α-imino ketones prepared by N-heterocyclic-carbene-catalyzed aroylation

An alternative synthetic route to 1,4,5-trisubstituted imidazoles from α-imino ketone, which can be prepared from imidoyl chlorides and aromatic aldehydes via N-heterocycle carbene-catalyzed aroylation was developed. This methodology consists of simple transformations, allowing a rapid access to imidazole derivatives with various aryl substituents at the desired positions.     

PHOTOREACTIVATION OF ULTRAVIOLET LIGHT-INDUCED DAMAGE IN CULTURED FISH CELLS AS REVEALED BY INCREASED COLONY FORMING ABILITY AND DECREASED CONTENT OF PYRIMIDINE DIMERS

Abstract— Cultured cells derived from a goldfish were irradiated with 254nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m²) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9 (40min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m²) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light.     

Scintillation properties of Yb-doped garnet crystals

Luminescence properties of heavily Yb-doped Lu₃Al₅O₁₂ (Yb:LuAG) and Lu₃Ga₅O₁₂ (Yb:LGG) single crystals grown by micro-pulling-down method were characterized. Charge transfer luminescence of Yb³⁺ was observed in both crystals. Photoluminescence spectra, temperature dependence of emission intensity and decay kinetics of these crystals were studied. Mean decay time of about 24 ns at 90 K (Yb5%:LuAG) and 21 ns at 110 K (Yb5%:LuGG) were observed. Strong thermal quenching at room temperature was measured for both Yb:LuAG and Yb:LGG.     

Hessenberg varieties,Slodowy slices,and integrable systems

Mathematische Zeitschrift - This work is intended to contextualize and enhance certain well-studied relationships between Hessenberg varieties and the Toda lattice, thereby building on the results...     

Localization of Chern–Simons type invariants of Riemannian foliations

We prove an Atiyah–Bott–Berline–Vergne type localization formula for Killing foliations in the context of equivariant basic cohomology. As an application, we localize some Chern–Simons type invariants, for example the volume of Sasakian manifolds and secondary characteristic classes of Riemannian foliations, to the union of closed leaves. Various examples are given to illustrate our method.     

Instanton counting on blowup. I. 4-dimensional pure gauge theory

We give a mathematically rigorous proof of Nekrasov’s conjecture: the integration in the equivariant cohomology over the moduli spaces of instantons on ℝ⁴ gives a deformation of the Seiberg-Witten prepotential for N=2 SUSY Yang-Mills theory. Through a study of moduli spaces on the blowup of ℝ⁴, we derive a differential equation for the Nekrasov’s partition function. It is a deformation of the equation for the Seiberg-Witten prepotential, found by Losev et al., and further studied by Gorsky et al. Mathematics Subject Classification (2000) 14D21, 57R57, 81T13, 81T60     

Performance of ceramic anvils for high pressure neutron scattering

Three kinds of ceramics, zirconia-toughened alumina (ZTA), alumina-toughened zirconia (ATZ) and yttria-stabilized zirconia (YSZ), were tested as anvil materials, mainly for the purpose of neutron scattering study under high pressure. ZTA with non-toroidal anvil profile, having the same sample volume as conventionally used double toroidal anvils, sustained pressures up to 11.9?GPa. This is comparable to anvils made of tungsten carbide (TC) with Ni binder with the same dimensions. ATZ would also be an alternative material to TC with pressure performance comparable to ZTA, whereas YSZ is much weaker than the other two ceramics. The attenuation coefficient for YSZ is significantly smaller than that of TC and similar to ZTA and ATZ, the latter being estimated by attenuation calculations. Neutron diffraction on a sample of lead in YSZ anvils as well as quasi-elastic neutron scattering on liquid water in ZTA also demonstrate the outstanding neutron transparency of these ceramics. The gain factor in count rate is up to one order of magnitude.     

Composite constituent: lactucenyl acetate, a novel migrated lupane triterpenoid from Lactuca indica revision of structure of tarolupenyl acetate

Lactucenyl acetate (1), a new member of migrated lupane triterpenoids was isolated from Lactuca indica and its structure was elucidated on the basis of spectral analyses. The structure of tarolupenyl acetate was revised as lup-19(21)-en-3β-yl acetate (2).     

呋喃类化合物在离子液体和硅胶负载离子液体中的Diels-Alder反应研

以1-丁基3-甲基咪唑盐作为离子液体阳离子,与三种不同阴离子BF4、PF6、Tf2N组成性质不同的三种离子液体,催化呋喃类和丁炔二羧酸酯之间发生的Diels-Alder反应,合成了一系列化合物,研究了离子液体的催化效果。研究表明,呋喃类化合物的极性越低, Diels-Alder 反应的活性越高。在含硫的呋喃类化合物的反应中,当以 [Bmim]PF6 作为离子液体时,Diels-Alder 反应的产率可达到53%。另外,当 [Bmim]PF6 离子液体被吸附在硅胶表面上时,Diels-Alder的反应产率有所提高。