New formation of a 1,3-dipole in the reaction of adamantanone azine with triazolinediones: In connection with reactivity toward singlet oxygen

Tricyclo[3.3.1.1]decanone azine ( adamantanone azine ) reacts with 4-substituted 1,2,4-triazoline-3,5-diones under elimination of diazo adamantane to give a 1,3-dipole ( “azomethinimine” ), which on treatment with dipolahophiles affords the [ 2 + 3] -cycloadducts. The reaction is compared with singlet oxygen oxidation.     

Chemical release control: Carbamates of 3-vinylphenyl and 2-methacryloyloxyethyl isocyanates and perfume and herbicide alcohols

Polymerizable carbamates were synthesized from 3-vinylphenyl and 2-methacryloyloxyethyl isocyanates and perfume and herbicide alcohols, such as 2-phenethyl alcohol, citronellol, geraniol, 1-menthol, borneol, and 2-(2,4-dichlorophenoxy)- and 2-(2,4,5-trichlorophenoxy)ethyl alcohols. Copolymerization of these carbamate monomers and N-vinyl-2-pyrrolidone with AIBN in dioxane gave respective copolymers. Hydrolyses of both monomers and copolymers, however, required severe acid conditions, although different chemical structures gave different hydrolytic behaviors.     

Surface friction of hydrogels with well-defined polyelectrolyte brushes

Hydrogels of poly(2-hydroxyethyl methacrylate) (PHEMA) with well-defined polyelectrolyte brushes of poly(sodium 4-styrenesulfonate) (PNaSS) of various molecular weights were synthesized, keeping the distance between the polymer brushes constant at ca. 20 nm. The effect of polyelectrolyte brush length on the sliding friction against a glass plate, an electrorepulsive solid substrate, was investigated in water in a velocity range of 7.5 x 10(-5) to 7.5 x 10(-2) m/s. It is found that the presence of polymer brush can dramatically reduce the friction when the polymer brushes are short. With an increase in the length of the polymer brush, this drag reduction effect only works at a low sliding velocity, and the gel with long polymer brushes even shows a higher friction than that of a normal network gel at a high sliding velocity. The strong polymer length and sliding velocity dependence indicate a dynamic mechanism of the polymer brush effect.     

Reaction of singlet oxygen with indanone phosphazine: formation of ketone and lactone

Photooxygenation of 1,1,3,3-tetramethyl-2-indanone triphenyl-phosphazine afforded, in addition to the parent indanone and triphenylphosphine oxide, 2,2,5,5-tetramethyl-3,4-benzo-3-penten-5-olide from a carbonyl oxide intermediate and also gave light emission.     

Interactions of enzymes and a lectin with a chitin-based graft copolymer having polysarcosine side chains

The molecular-recognition abilities of a water-soluble chitin derivative, chitin-graft-polysarcosine (2) were investigated using chitinase, lysozyme, and wheat germ agglutinin (WGA). The enzymatic degradabilities of 2 were evaluated using chitinase and lysozyme. The molecular weight of those compounds of 2 with a higher affinity toward water decreased rapidly, as compared with partially deacetylated chitin (1). The 1H NMR spectrum of the low-molecular-weight fraction, yielded after lysozymic hydrolysis, indicated that saccharide residues in the chitinous backbone were specifically recognized by the lysozyme, then beta-glycosidic linkages in the backbone were selectively hydrolyzed. Furthermore, the molecular-recognition ability of the chitinous backbone of graft copolymer 2 toward the lectin WGA was elucidated by the enzyme-linked lectin-binding assay (ELLA). It was revealed that the graft copolymer with a lower degree of substitution (DS) value efficiently interacted with WGA. Interestingly, a graft copolymer having longer polysarcosine side chains showed higher recognition ability toward WGA than that having short side chains.     

Passive Q-switching of a diode-side-pumped Nd-doped mixed gadolinium yttrium vanadate bounce laser

High power passive Q-switching was achieved with a pulse width of 18–32 ns by using a diode-side-pumped Nd:Gd_0.6Y_0.4VO₄ bounce amplifier. An average output power of > 8 W was obtained at a pump power of 39 W. The peak power of the Q-switched output was adjusted within 1.9–5.2 kW by changing the Nd concentration. The mixed vanadates showed significantly higher Q-switching performances in comparison with pure Nd:GdVO₄. PACS 42.55.Xi; 42.60.Gd; 42.60.Da     

Nonlinear resonances and self-excited oscillations of a rotor caused by radial clearance and collision

This paper investigates oscillations in a flexible rotor system with radial clearance between an outer ring of the bearing and a casing by experiments and numerical simulations. The mathematical model considers the collisions of the bearing with the casing. The following phenomena are found: (1) Nonlinear resonances of subharmonic, super-subharmonic and combination oscillation occur. (2) Self-excited oscillation of a forward whirling mode occurs in a wide range above the major critical speed. (3) Entrainment phenomena from self-excited oscillation to nonlinear forced oscillation occur at these nonlinear resonance ranges. Moreover, this study analyzes periodic solutions of the mathematical model by the Harmonic Balance Method (HBM). As the results, the nonlinear resonances of subharmonic oscillation and its entrainment phenomenon can be explained theoretically by investigating the stability of the periodic solutions. The influence of the static force and the bearing damping on these oscillation are also clarified.     

Tunable, visible phase conjugator with a saturable-amplifier polymer laser dye

We present the first report to the best of our knowledge of highly efficient phase conjugation in a laser-pumped polymer-dye saturable amplifier. Phase-conjugate reflectivity of as much as 210% at 560 nm has been obtained. Moreover, efficient reflectivity has been obtained in the broad wavelength region from 556 to 567 nm.     

Modal Power Analysis for Two-Mode Fibers Illuminated by an Offset Beam Based on Near Field Pattern Measurement

A novel method for determining mode power distribution in a two-mode fiber illuminated by an offset beam by measuring the near field pattern on the test fiber endface is developed. This method utilizes the different field symmetries of the fundamental and the second order modes. Coupling efficiencies from a quasi Gaussian beam to the fundamental and the second order modes in a two mode fiber were measured by the new technique for various offset launching conditions, and were in good agreement with the theoretical ones.