Dynamic Switching of the Circularly Polarized Luminescence of Disubstituted Polyacetylene by Selective Transmission through a Thermotropic Chiral Nematic Liquid Crystal

The circularly polarized luminescence (CPL) of chiral disubstituted liquid‐crystalline polyacetylene (di‐LCPA) can be dynamically switched and amplified from left‐ to right‐handed CPL and vice versa through the selective transmission of CPL across a thermotropic chiral nematic liquid crystal (N*‐LC) phase. By combining a chiral di‐LCPA CPL‐emitting film with an N*‐LC cell and tuning the selective reflection band of the N*‐LC phase to coincide with the CPL emission band, a CPL‐switchable cell was constructed. The phase change induced by the thermotropic N*‐LC cell by varying the temperature leads to a change in the selective transmission of CPL, which enables the dynamic switching and amplification of CPL. It is anticipated that CPL‐switchable devices might find applications in switchable low‐threshold lasers and optical memory devices.     

Chemical and Electrochemical Syntheses of Soluble Electroconducting Poly(2,5-Thienylene) Derivatives

Soluble electroconducting poly[3 -(ω-phenylalkyl)-2,5 -thienylene)]s are synthesized by electrochemical and chemical polymerizations of 3-(2-phenylethyl)thiophene and 3-(3-phenylpropyl)thiophene, which are synthesized by a Grignard cross-coupling reaction of l-bromo-3-phenylalkane with 3-bromothiophene in the presence of dichloro[1,3-bis(diphenylphosphino)propane]-nickel(II). The chemical, electrochemical, and electrical properties of these polymers are reported, including initial characterization, spectroscopy, and electrochemical cyclic voltammetry.     

Determination of rare-earth elements in a limestone geological standard reference material by ICP-MS following solvent extraction.

Rare-earth elements in a limestone geological standard (JLs-1) were determined by inductively coupled plasma mass spectroscopy (ICP-MS) using phosphoric acid 2-ethylhexyl ester solvent extraction, which had been established for seawater analysis. First, the limestone sample was divided into two fractions: acetic acid soluble (carbonate fraction) and insoluble (residue). A modification of the method was undertaken to achieve quantitative recovery. With this method most of the REEs in the carbonate fraction were quantitatively recovered, except for the heaviest three REEs (Tm, Tb and Lu). The reason for the poor recoveries of the three elements was investigated, but still remained unclear. The mass-spectroscopic interference of BaO with Eu made an accurate determination of both lighter REEs and Eu at the same time impossible. The precision of this method was better than 20%. The data adopted after analytical consideration were consistent with those previously reported.     

Hierarchically controlled helical graphite films prepared from iodine-doped helical polyacetylene films using morphology-retaining carbonization

One-handed helical graphite films with a hierarchically controlled morphology were prepared from iodine-doped helical polyacetylene (H-PA) films using the recently developed morphology-retaining carbonization method. Results from scanning electron microscopy indicate that the hierarchical helical morphology of the H-PA film remains unchanged even after carbonization at 800 °C. The weight loss of the film due to carbonization was very small; only 10-29% of the weight of the film before doping was lost. Furthermore, the graphite film prepared by subsequent heating at 2600 °C retained the same morphology as that of the original H-PA film and that of the helical carbon film prepared at 800 °C. The screwed direction, twisted degree, and vertical or horizontal alignment of the helical graphite film were well controlled by changing the helical sense, helical pitch, and orientation state of the chiral nematic liquid crystal (N*-LC) used as an asymmetric LC reaction field. X-ray diffraction and Raman scattering measurements showed that graphitic crystallization proceeds in the carbon film during heat treatment at 2600 °C. Transmission electron microscopy measurements indicate that ultrasonication of the helical graphite film in ethanol for several hours gives rise to a single helical graphite fibril. The profound potentiality of the present graphite films is exemplified in their electrical properties. The horizontally aligned helical graphite film exhibits an enhancement in electrical conductivity and an evolution of electrical anisotropy in which conductivity parallel to the helical axis of the fibril bundle is higher than that perpendicular to the axis.     

Syntheses of Prekinamycin and a Tetracyclic Quinone from Common Synthetic Intermediates

Towards total synthesis of a series of kinamycin and related antibiotics via common synthetic intermediates, total synthesis of prekinamycin was achieved via Suzuki coupling of naphthaleneboronic acid and bromobenzene derivative, intramolecular Friedel? Crafts reaction of 2‐(naphthalen‐2‐yl)benzoic acid, and diazotization in ten steps from 3,5‐dimethylphenol. Synthetic studies towards kinamycin antibiotics was also examined, and the tetracyclic quinone core for kinamycins was synthesized. Palladium‐catalyzed site‐selective hydroxylation of a benzoic acid derivative with the AB‐D ring part was successfully applied to the selective D‐ring functionalizations.     

Synthesis of jadomycin A and related jadomycin aglycons: structural re-examination of jadomycins S and T may be needed

Jadomycin A and related jadomycin M and W aglycons were synthesized. Easy re-construction of 4-(hydroxymethyl)-1,3-oxazolidin-5-one system into an isomeric 1,3-oxazolidine-4-carboxylic acid system during the synthetic trial of jadomycin S aglycon requests us to more precisely re-examine the structures proposed for jadomycins S and T, derived from hydroxyl-containing amino acids of l-serine and l-threonine, respectively.     

Asymptotic behavior of viscosity solutions for a degenerate parabolic equation associated with the infinity-Laplacian

The asymptotic behavior of viscosity solutions to the Cauchy–Dirichlet problem for the degenerate parabolic equation u _t  = Δ_∞ u in Ω × (0,∞), where Δ_∞ stands for the so-called infinity-Laplacian, is studied in three cases: (i) and the initial data has a compact support; (ii) Ω is bounded and the boundary condition is zero; (iii) Ω is bounded and the boundary condition is non-zero. Our method of proof is based on the comparison principle and barrier function arguments. Explicit representations of separable type and self-similar type of solutions are also established. Moreover, in case (iii), we propose another type of barrier function deeply related to a solution of . Goro Akagi was supported by the Shibaura Institute of Technology grant for Project Research (no. 2006-211459, 2007-211455), and the grant-in-aid for young scientists (B) (no. 19740073), Ministry of Education, Culture, Sports, Science and Technology. Petri Juutinen was supported by the Academy of Finland project 108374. Ryuji Kajikiya was supported by the grant-in-aid for scientific research (C) (no. 16540179), Ministry of Education, Culture, Sports, Science and Technology.     

A hybrid microphone array post-filter in a diffuse noise field

In this paper, a hybrid post-filter for microphone arrays with the assumption of a diffuse noise field is proposed to suppress correlated as well as uncorrelated noise. In the proposed post-filter, a modified Zelinski post-filter, which is estimated using the signals on the microphone pairs on which noises are uncorrelated by considering the correlation characteristics of noise impinging on different microphone pairs, is applied to the high frequencies to suppress spatially uncorrelated noise; a single-channel Wiener post-filter is applied to the low frequencies for cancellation of spatially correlated noise. In theory, the proposed post-filter is a Wiener post-filter. In practice, experiments using multi-channel recordings were conducted, and experimental results demonstrate the usefulness and superiority of the proposed post-filter compared to other post-filters using speech quality measures and speech recognition rate.     

Sharpness and amplitude envelopes of broadband noise

This paper discusses how amplitude envelope shapes, sound-pressure level, and duration of broadband noise affect sharpness and brightness. In the first experiment, sharpness, brightness, and similarity were judged for paired stimuli by 13 subjects. The stimuli consisted of broadband noise with different types of amplitude envelopes, sound-pressure levels, and duration. Experimental results were analyzed with a multidimensional scaling technique. In addition, the second experiment measuring the point of subjective equality (PSE) of sharpness was carried out for four subjects. The results of these two experiments showed large individual differences in sharpness judgment, difficulty in brightness judgment for the stimuli used in the experiments, and influence of the amplitude envelope shapes on sharpness. The individual differences observed in sharpness judgment were explained by the differences between weights given to two psychological dimensions: loudness and subjective duration. This study forms a basis for understanding sharpness of nonsteady sounds.