Non-contact acoustic tests based on nanosecond laser ablation: Generation of a pulse sound source with a small amplitude

A method to generate a pulse sound source for acoustic tests based on nanosecond laser ablation with a plasma plume is discussed. Irradiating a solid surface with a laser beam expands a high-temperature plasma plume composed of free electrons, ionized atoms, etc. at a high velocity throughout ambient air. The shockwave generated by the plasma plume becomes the pulse sound source. A laser ablation sound source has two features. Because laser ablation is induced when the laser fluence reaches 10¹²–10¹⁴ W/m², which is less than that for laser-induced breakdown (10¹⁵ W/m²), laser ablation can generate a lower sound pressure, and the sound source has a hemispherical radiation pattern on the surface where laser ablation is generated. Additionally, another feature is that laser-induced breakdown sound sources can fluctuate, whereas laser ablation sound sources do not because laser ablation is produced at a laser beam–irradiation point. We validate this laser ablation method for acoustic tests by comparing the measured and theoretical resonant frequencies of an impedance tube.     

Neighboring effect of the sodium carboxylate group on the saponification of diallyl phthalate prepolymer

The neighboring effect of sodium carboxylate groups on the saponification of diallyl phthalate prepolymer was investigated in detail in dioxane solutions that contained various amounts of water at 50°C by using different types of model compound; this procedure is also compared with the neighboring effect of hydroxyl groups.     

CHLORPROMAZINE PHOTOSENSITIZATION—I. EFFECT OF NEAR-UV IRRADIATION ON BACTERIOPHAGES SENSITIZED WITH CHLORPROMAZINE

Abstract— Both DNA bacteriophage and RNA bacteriophage were inactivated when they were irradiated with near-UV light (black light) in the presence of chlorpromazine. The far-UV sensitive mutants of T4D, i.e. T4D v , T4D px and T4D y , were no more sensitive to near-UV light plus chlorpromazine than the wild type. Electron microscopic observations showed that adsorption of T4D was greatly influenced by the treatment. The present results may indicate that the inactivation of T4D is due to the loss of adsorption caused by impairment in the tail or the tail fiber protein rather than the inactivation of DNA.     

Redox‐Responsive Hydrogel System Using the Molecular Recognition of β‐Cyclodextrin

Summary: We have successfully constructed a redox‐responsible hydrogel system by combination of β‐cyclodextrin (β‐CD), dodecyl‐modified poly(acrylic acid) [p(AA/C₁₂)], and a redox‐responsive guest, ferrocenecarboxylic acid (FCA). In the reduced state of FCA, the ternary mixture exhibited a gel‐like behavior, whereas, in its oxidized state, the mixture exhibited a sol behavior.

Conceptual illustration for the redox‐responsive hydrogel system.     

Macromolecular Recognition by Polymer‐Carrying Cyclodextrins: Interaction of a Polymer Bearing Cyclodextrin Moieties with Poly(acrylamide)s Bearing Aromatic Side Chains

Summary: The interaction of a polymer bearing β‐cyclodextrin moieties (β‐CD polymer) with poly(acrylamide)s bearing aromatic side chains was investigated by viscometry to study the effect of collectivity (i.e., interactions at multi‐sites) in macromolecular recognition. The formation of inclusion complexes at multi‐sites caused a large difference in the size of interpolymer aggregates, even though the difference in association constants for complexation of native β‐CD with guest moieties was not very much large.

Conceptual illustration for interpolymer aggregates of β‐CD polymer with poly(acrylamide)s bearing naphthyl groups substituted on the (a) 1‐ and (b) 2‐positions (see Scheme 1 ).     

Practical and efficient synthesis of the (R)-atropisomer of a 4-phenyl 1,2,4-triazole derivative as a selective GlyT1 inhibitor

Herein we describe a novel and efficient method for synthesizing the (R)-atropisomer of 3-[3-ethyl-5-(6-phenylpyridin-3-yl)-4H-1,2,4-triazol-4-yl]-2-methylbenzonitrile 1, a novel GlyT1 inhibitor. The diastereomeric salt formation of 3-[3-ethyl-5-(6-phenylpyridin-3-yl)-4H-1,2,4-triazol-4-yl]-2-methylbenzoic acid 7 with (1R,2S)-(?)-2-amino-1,2-diphenylethanol afforded the desired (R)-atropisomer. We also report the determination of the absolute configuration of (R)-7 by powder X-ray diffraction.     

Classification of Minimal Actions of a Compact Kac Algebra with Amenable Dual

We show the uniqueness of minimal actions of a compact Kac algebra with amenable dual on the AFD factor of type II₁. This particularly implies the uniqueness of minimal actions of a compact group. Our main tools are a Rohlin type theorem, the 2-cohomology vanishing theorem, and the Evans-Kishimoto type intertwining argument.     

Polymerization of monoallyl phthalate

Radical polymerization of monoallyl phthalate (MAP) was conducted at 70, 80, and 90°C, benzoyl peroxide being used as an initiator. It was found that the analytical values of the polymer obtained were always lower than the calculated ones for MAP homopolymer and nearly constant regardless of the polymerization conditions. From the detailed investigation it was concluded that the results are due to the formation of polymer including about 20 mole % of allyl alcohol units; such allyl alcohol units might be incorporated into the polymer through propagation accompanied by partial elimination of phthalic anhydride.     

Generalisations of the Haagerup approximation property to arbitrary von Neumann algebras

The notion of the Haagerup approximation property, originally introduced for von Neumann algebras equipped with a faithful normal tracial state, is generalised to arbitrary von Neumann algebras. We discuss two equivalent characterisations, one in term of the standard form and the other in term of the approximating maps with respect to a fixed faithful normal semifinite weight. Several stability properties, in particular regarding the crossed product construction are established and certain examples are introduced.     

Damage detection in membrane structures using non-contact laser excitation and wavelet transformation

In this paper, a vibration testing and health monitoring system based on an impulse response excited by laser is proposed to detect damage in membrane structures. A high power Nd: YAG pulse laser is used to supply an ideal impulse to a membrane structure by generating shock waves via laser-induced breakdown in air. A health monitoring apparatus is developed with this vibration testing system and a damage detecting algorithm which only requires the vibration mode shape of the damaged membrane. Artificial damage is induced in membrane structure by cutting and tearing the membrane. The vibration mode shapes of the membrane structure extracted from vibration testing by using the laser-induced breakdown and laser Doppler vibrometer are then analyzed by 2-D continuous wavelet transformation. The location of damage is determined by the dominant peak of the wavelet coefficient which can be seen clearly by applying a boundary treatment and the concept of an iso-surface to the 2-D wavelet coefficient. The applicability of the present approach is verified by finite element analysis and experimental results, demonstrating the ability of the method to detect and identify the positions of damage induced on the membrane structure.