An easy access to 7-methyl-2-naphthalenecarbonitrile

A practical and cost-effective procedure has been developed for the synthesis of 7-methyl-2-naphthalenecarbonitrile, the precursor of the anticoagulant agents YM-60828 or YM-96765. This new route generates the key intermediate in only two steps from readily available 3-cyanopropionaldehyde dimethyl acetal and m-tolualdehyde, without requiring chromatographic purification. The synthesis involves condensation of the cyano derivative with the aldehyde and subsequent cyclodehydration.     

The influence of the adsorption of surface active substance on the rate constant of the electrode reaction

The electrode reaction of copper-EDTA complex was studied polarographically in the presence of polyvinylalcohol. The d.c. polarographic current-time curves were analyzed by using the equation given by Matsuda for the diffusion process of the depolarizer influenced by the adsorbates. The rate constants affected by the adsorption are assumed to be composed of two parts at relatively high coverage, i.e., one is the rate constant of the electrode reaction at free surface of DME and the other the rate constant of the electrode reaction through the adsorded layer. The rate constant at the uncovered surface was analyzed by a formula analogous to that proposed by Parsons and it was shown that one of the parameters involved in the formula depends on the electrode potential. On the other hand, it was shown that the electrode reaction at the covered surface is irreversible, and its cathodic rate constant depends on the electrode potential exponentially.     

Surface-emitted terahertz-wave difference-frequency generation in two-dimensional periodically poled lithium niobate

We report on the demonstration of surface-emitted terahertz- (THz-) wave difference-frequency generation from two-dimensional (2D) periodically poled lithium niobate (PPLN). The two orthogonal periodic structures individually compensate for both the phase mismatch of the launched lasers and the generated THz wave. Tunable 1.5-1.8 THz wave generation with a bandwidth of 10-GHz was obtained by use of two 2D PPLN crystals. We also confirmed that THz waves were simultaneously generated into two opposite directions, which suggests the possibility of higher THz-wave output power.     

Phase isomerism in gear-shaped molecules

The concept of new stereoisomerism due to different phase relations between the labeled cogs in a smoothly geared molecule is described.     

Reaction of (diacetoxyiodo)benzene with excess of trifluoromethanesulfonic acid. A convenient route to para-phenylene type hypervalent iodine oligomers

Reaction of (diacetoxyiodo)benzene [PhI(OAc)₂] in trifluoromethanesulfonic acid (TfOH) resulted in oligomerization of PhI(OAc)₂. Quenching with NaBr gave the bromide salts of hypervalent iodine oligomers that were determined by thermolysis with KI to be a para phenylene type of oligomers. Neutralization of the reaction mixture of PhI(OAc)₂ and TfOH with aqueous NaHCO₃ yielded the triflate salts of iodine oligomers. Furthermore, quenching the reaction mixture with aromatic substrates afforded arylated iodine oligomers. These iodine oligomers were found to be 3-4 of the number average degree of polymerization (P_n) by GC analysis of the thermolysis products and ¹H NMR analysis. The major products, trimer and tetramer, were synthesized independently.     

Growth of low defect density GaP layers on Si substrates within the critical thickness by optimized shutter sequence and post-growth annealing

We have developed a growth procedure for realizing a low defect density GaP layer on an Si substrate. The growth procedure consists of two parts. One is the post-growth annealing for the annihilation of stacking faults (SFs). We have investigated an annihilation mechanism with molecular beam epitaxy grown GaP layers. 1-monolayer-thick SFs typically generate from the GaP/Si interface in a non-annealed GaP layer. In a 700 °C annealed GaP layer, generation points of these SFs tend to shift toward the GaP surface. In a 730 °C annealed GaP layer, SFs density is effectively decreased. These results suggest that SFs are annihilated through the climb motion of two partial dislocations during the post-growth annealing. Another one is the optimized shutter sequence for migration enhanced epitaxy. We have revealed that it is effective for the suppression of both three-dimensional growth and melt-back etching to increase in a stepwise manner the number of supplied Ga atoms per cycle. As a result, the generation of threading dislocations and pits is remarkably suppressed. A root mean square surface roughness of 0.13 nm is obtained within the critical thickness. We have estimated etch pit density (EPD) to be ∼7×10⁵ cm⁻² with a GaPN/GaP/Si structure. To the best of our knowledge, this value is same as that of commercially available GaP substrates and is the lowest one in the EPD of GaP/Si heteroepitaxy.     

Irregularly shaped ice aggregates in optical modeling of convectively generated ice clouds

We propose a model of irregular shaped ice particles for satellite and ground-based cloud remote sensing applications. Microphysical observations have shown that ice particles generated in convective clouds tend to have highly irregular structures as a result of aggregation process. To simulate such complex structures, we used spatial Poisson–Voronoi tessellations. Furthermore, we adopted fractal-like shapes that were consistent with the proposed mass-dimension and area ratio-dimension relationships of measured cirrus particles. Single-scattering properties of the modeled “Voronoi aggregates” at visible wavelengths with size parameters up to 2246 were estimated from numerical calculations using the finite-difference time-domain method and the geometrical-optics integral-equation method. The phase functions for randomly oriented Voronoi aggregates showed features with no halos in the forward-scattering direction and a flat angular dependence in the side-to-backscattering directions. These characteristics and resultant asymmetry factors agreed with those of measured ice particles. Moreover, we confirmed the weak size and shape dependences of these scattering properties for the Voronoi aggregates, as well as high backscattering depolarization ratios and low linear polarizations.     

Application of high-resolution ESI and MALDI mass spectrometry to metabolite profiling of small interfering RNA duplex

We investigated the application of a high-resolution Orbitrap mass spectrometer equipped with an electrospray ionization (ESI) source and a matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometer to the metabolite profiling of a model small interfering RNA (siRNA) duplex TSR#34 and compared their functions and capabilities. TSR#34 duplex was incubated in human serum in vitro, and the duplex and its metabolites were then purified by ion exchange chromatography in order to remove the biological matrices. The fraction containing the siRNA duplex and its metabolites was collected and desalted and then subjected to high-performance liquid chromatography (HPLC) equipped with a reversed phase column. The siRNA and its metabolites were separated into single strands by elevated chromatographic temperature and analyzed using the ESI-Orbitrap or the MALDI-TOF mass spectrometer. Using this method, the 5' and/or 3' truncated metabolites of each strand were detected in the human serum samples. The ESI-Orbitrap mass spectrometer enabled differentiation between two possible RNA-based sequences, a monoisotopic molecular mass difference which was less than 2 Da, with an intrinsic mass resolving power. In-source decay (ISD) analysis using a MALDI-TOF mass spectrometer allowed the sequencing of the RNA metabolite with characteristic fragment ions, using 2,4-dihydroxyacetophenone (2,4-DHAP) as a matrix. The ESI-Orbitrap mass spectrometer provided the highest mass accuracy and the benefit of on-line coupling with HPLC for metabolite profiling. Meanwhile, the MALDI-TOF mass spectrometer, in combination with 2,4-DHAP, has the potential for the sequencing of RNA by ISD analysis. The combined use of these methods will be beneficial to characterize the metabolites of therapeutic siRNA compounds. Copyright ? 2012 John Wiley & Sons, Ltd.     

Analog Metal-Oxide-Semiconductor Integrated Circuit Implementation of Approach Detection with Simple-Shape Recognition Based on Visual Systems of Lower Animals

We proposed an analog network for motion detection of an approaching object with simple-shape recognition based on the visual systems of lower animals. Locusts can detect an approaching object by performing a simple process in a descending contralateral motion detector (DCMD) existing in their brain, which senses the increase in size and expansion velocity of the image projected on a retina just before collision. The responses correspond to the approaching velocity and direction. Frogs can recognize a simple shape by performing a simple process in a tectum and thalamus existing in their brain based on retinal information; this is called the Ewert von Seelen model. The proposed network was constructed with simple analog metal-oxide-semiconductor (MOS) circuits. Simulation results with a simulation program with integrated circuit emphasis (SPICE) showed that the network was able to detect the approaching velocity and direction, and also recognized simple shapes such as a circle, square, triangle and rectangle.     

Paradigm Shift from Alkaline (Earth) Metals to Early Transition Metals in Fluoroorganometal Chemistry: Perfluoroalkyl Titanocene(III) Reagents Prepared via Not Titanocene(II) but Titanocene(III) Species

Perfluoroalkyl (R_F) titanocene reagents [Cp₂Ti^IIIR_F] synthesized via [Cp₂Ti^IIICl] rather than [Cp₂Ti^II] show new types of perfluoroalkylation reactions. The [Cp₂Ti^IIIR_F] reagents exhibit a wide variety of reactivity with carbonyl compounds including esters and nitriles, and selectivities far higher than those reported for conventional R_FLi and R_FMgX reagents.