An efficient and selective conversion of sorbitol in ionic liquids: Use of ion exchange resin as a solid acid catalyst

Sorbitol was readily converted by heating in hydrophobic ionic liquids by the presence of ion exchange resins. Chemoseletivity of the dehydration depended on the choice of ion exchange resin; Nafion selectively produced isosorbide while Amberlite gave 1,5-anhydrosorbitol along with unreacted sorbitol. Ionic liquids used in the reaction were readily recovered by simple extraction procedure. With these procedures, we succeeded to prepare isosorbide in pure form, not contaminated with either ionic liquids or acid catalyst, by simple experimental procedure.     

PIDA-mediated synthesis of oxazoles through oxidative cycloisomerization of propargylamides

PIDA [phenyliodine(III) diacetate] in AcOH or AcOH-HFIP (hexafluoroisopropanol) efficiently promotes the formation of 2,5-disubstituted oxazoles via the oxidative cycloisomerization of propargylamide derivatives.     

Detecting coupled collective motions in protein by independent subspace analysis

Protein dynamics evolves in a high-dimensional space, comprising aharmonic, strongly correlated motional modes. Such correlation often plays an important role in analyzing protein function. In order to identify significantly correlated collective motions, here we employ independent subspace analysis based on the subspace joint approximate diagonalization of eigenmatrices algorithm for the analysis of molecular dynamics (MD) simulation trajectories. From the 100 ns MD simulation of T4 lysozyme, we extract several independent subspaces in each of which collective modes are significantly correlated, and identify the other modes as independent. This method successfully detects the modes along which long-tailed non-Gaussian probability distributions are obtained. Based on the time cross-correlation analysis, we identified a series of events among domain motions and more localized motions in the protein, indicating the connection between the functionally relevant phenomena which have been independently revealed by experiments.     

Ion-pair structure of vaporized ionic liquid studied by matrix-isolation FTIR spectroscopy with DFT calculations: a case of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate

The matrix-isolation infrared spectrum of a thermally evaporated ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][OTf]), was measured by FTIR spectroscopy and analyzed with the aid of DFT calculations. The main chemical species in the observed IR spectrum was mainly identified as the 1:1 cation-anion pair, which corresponds to the second stable ion-pair structure bonded through five hydrogen bonds between three O atoms of the anion side and four H atoms of the cation.     

Counter-current chromatographic separation of nucleic acid constituents with a hydrophilic solvent system

Nucleic acid constituents such as nucleobases, nucleosides and nucleotides were separated by counter-current chromatography using type J coil planet centrifuge. The separation was performed with a hydrophilic solvent system composed of 1-propanol/800 mM potassium phosphate buffer (pH 7.4) (1:1, v/v) by eluting the lower aqueous phase at a flow-rate of 0.5 ml/min. Eight selected nucleic acid constituents (4.0 mg, 0.5 mg of each), uridine monophosphate (UMP), adenosine monophosphate (AMP), deoxyadenosine monophosphate (dAMP), uridine, urasile, deoxy uridine, adenosine and adenine were well resolved within 160 min.     

3D atomic imaging by internal-detector electron holography

A method of internal-detector electron holography is the time-reversed version of photoelectron holography. Using an energy-dispersive x-ray detector, an electron gun, and a computer-controllable sample stage, we measured a multiple-energy hologram of the atomic arrangement around the Ti atom in SrTiO3 by recording the characteristic Ti Kα x-ray spectra for different electron beam angles and wavelengths. A real-space image was obtained by using a fitting-based reconstruction algorithm. 3D atomic images of the elements Sr, Ti, and O in SrTiO3 were clearly visualized. The present work reveals that internal-detector electron holography has great potential for reproducing 3D atomic arrangements, even for light elements.     

InGaAsP multiple quantum well edge-emitting light-emitting diode showing low coherence characteristics using selective-area metalorganic vapor phase epitaxy

Low coherence multiple-quantum well edge-emitting light-emitting diodes were obtained using selective-area metalorganic vapor-phase epitaxial growth, which utilized growth rate enhancement on an open stripe region between mask stripes. An optical absorption region, which was controlled by selective-area growth, was introduced to suppress optical feedback. At a driving current of 100 mA and an ambient temperature of 25°C, a power of 55 μW was coupled into a single-mode fiber, and a broad spectrum without spectral ripple was observed. Low coherence characteristics and very small temperature dependence were obtained in the temperature range from -40°C to 85°C. The modulation bandwidth was 210 MHz at a bias current of 100 mA.     

Dynamics of FLCs with a tilted bookshelf structure using time-resolved FTIR spectroscopy

Time-resolved FTIR spectroscopy with microsecond resolution was applied to the switching process of FLCs using an IR polarizer attached to a microscope whose axis was set along the aligning direction (direction of SiO flux). A tilted bookshelf geometry with a layer tilt angle of approximately 34° was obtained by alignment using obliquely evaporated SiO layers in a CaF₂ cell with about 1.7 μm gap. Six kinds of FLC mixtures were prepared by mixing 5 wt % of a chiral molecule with host mixtures of phenylpyrimidines. By monitoring an absorption band at 1432 cm^-1, assigned to vibrational modes of the pyrimidine skeleton, it was found that the molecular long axis either rotates along the upper side or along the lower side of the cone during switching. Moreover, we investigated the relationship between the rotational direction of the directors and the stability of the dark level transmission during multiplexing. The dark level transmission during rotation along the upper side of the cone may fluctuate less than that during rotation along the lower side of the cone. We found that the bias stability of the dark level transmission is closely related to the direction of the rotation along the cone. The direction of the rotation of FLCs along the cone was therefore found to play an important role in realizing high contrast ratios during multiplexing.     

Whole field spatial frequency analysis of double-or multiple-exposed PIV images

Speckle Velocimetry or high-image density PIV gives a velocity vector map of a twodimensional flow field by point-by-point spatial frequency analysis of local pattern at an interrogation spot in a double- or a multiple-exposed image of laser speckle or pseudo-speckle pattern generated by pulsed laser-light-sheet illuminations of a plane in the flow densely seeded with fine particles. The whole field spatial frequency analysis of the double- or multiple-exposed PIV image gives more useful information of the flow field. Optical Fourier transform is a conventional technique not only for the local spatial frequency analysis but for the whole field analysis. Filtering of spatial frequency is one of the typical techniques for the latter which can reconstruct a velocity contour or a component velocity contour map of the flow. Fundamentally this technique is a simple and efficient analogue method to get more information in the velocity field analysis of the flow than a digital image processing, but in practical applications the measurement is restricted to simple flows because of optical noise and low spatial resolution. In order to improve the technique, the fundamental characteristics of the filtering and the noise yielded in the filtering process must be investigated. Meanwhile, wavelet analysis can also be applied to the whole field spatial frequency analysis of PIV image. In this paper the filtering technique is examined by numerical convolution integral, and the results obtained are compared with ones obtained by the wavelet analysis.