Commercially available simple ionic liquids-promoted dehydrative carbon–carbon bond-forming reaction of diarylmethanols and triarylmethanols with pyrroles,thiophene, furan and indoles

Two commercially available simple ionic liquids, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and 1-ethyl-2,3-dimethylimidazolium trifluoromethansulfonate, effectively promote the solvent-free dehydrative carbon–carbon (C–C) bond-forming reaction of a variety of diarylmethanols and triarylmethanols with π-rich heteroaromatics, such as pyrroles, indole, furan, and thiophene without ring-opening and polymerization to give the corresponding not only 2-substituted pyrroles, furan, and thiophene but also 3-substituted indoles in good to excellent yields with moderate to excellent regioselectivities. These dehydrative C–C bond formation reactions of alcohols offer several advantages, such as the use of stoichiometric amounts of π-rich heteroaromatics and ionic liquids, water is the only by-product, there is no need for either organic solvents or expensive metal or strong Brønsted acid catalysts in the reaction, and the diversity of diarylmethylation and triarylmethylation.     

Mössbauer spectroscopic study of nonstoichiometric perovskite,Ba1−xCaxFeO3−δ

Nonstoichiometric perovskites, Ba_1?xCa_xFeO_3?δ, were prepared by a pyrolysis of the mixture of Ba, Ca and Fe citrates. The amount of oxygen deficiency increases with the increase of Ca content. A new magnetic species was observed at room temperature in Mössbauer spectra of Ba_1?xCa_xFeO_3?δ. It is supposed that the iron species would occupy an intermediate site of octahedral and tetrahedral coordinations.     

Interferometry for measuring large aspherical surfaces with holographic optical elements

Interferometry for measuring the shape of large aspherical surfaces is reported. The interference fringe pattern between the parallel reference beam and the reconstructed wavefront from the master zone plate which is drawn by an electron-beam drawing machine is recorded on a hologram plate with off-axis optical arrangement. The hologram plate used as the standard element is reconstructed by the conjugate beam in a modified Twyman-Green interferometer. Insufficient parallelism of commercial hologram plates can be compensated by this method. It is also easy to make replicas. Some experimental results are also presented.     

Diffuse phase transition in rare earth ion doped SBN

The diffuse transition of a rare earth ion doped SBN (Ba_xSr_1?xNb₂O₆) was studied by measuring the spontaneous polarization P_s, and the dielectric constant ?. The phase transition of SBN can be regarded as a special case of a second order transition.     

The stability of generalized Volterra equations

In this paper, a particular type of a system of generalized Volterra equations [1], whose solutions are assured to be nonnegative for arbitrary nonnegative initial values, is considered. The extended stability theorem of LaSalle is used for deriving conditions for a nonnegative equilibrium point to be stable with respect to a certain subset of the Euclidean space. The obtained stability theorem has a close relation with Lyapunov's stability condition for linear systems with constant coefficients and is generally less restrictive than conditions known so far.     

Photo-induzierte Bildung von Peroxiden in Sacchariden und verwandten Verbindungen

Ohne Zusammenfassung     

Optical ultramicrometer technique utilizing a composite diffraction grating

Precise control of positioning or alignment technique utilizing a “composite diffraction grating” formed by superimposing a pair of gratings is proposed. Positioning accuracy of ±0.1 μm has been achieved in the preliminary experiments using dual transmission gratings. This indicates a novel method of sensitive detection of a displacement.