Synthesis of Azulene Derivatives from 2H-Cyclohepta[b]furan-2-ones as Starting Materials: Their Reactivity and Properties

A variety of synthetic methods have been developed for azulene derivatives due to their potential applications in pharmaceuticals and organic materials. Particularly, 2H-cyclohepta[b]furan-2-one and its derivatives have been frequently used as promising precursors for the synthesis of azulenes. In this review, we describe the development of the synthesis of azulenes by the reaction of 2H-cyclohepta[b]furan-2-ones with olefins, active methylenes, enamines, and silyl enol ethers as well as their reactivity and properties.     

Two-stage-type electrostatic precipitator re-entrainment phenomenaunder diesel flue gases

One of the applications of the electrostatic precipitator (ESP) is the cleaning of air to increase the visibility index in highway tunnels. Particles floating in air in highway tunnels are mainly carbon. Collection efficiency of a large particle diameter in an ESP often decreases when the ESP collects carbon particles which have low electric resistance. Collection efficiency often becomes negative in an experimental ESP. The negative collection efficiency means that the particle concentration flowing downstream is greater than that upstream in the ESP. This phenomenon is explained as the re-entrainment of particles. In this paper, experiments were carried out to investigate the cause of the decrease in efficiency of particle collection of the ESP. The time characteristic of the collection efficiency and the distribution of particle size on the collection electrodes were studied. Experimental results showed that the decrease in the collection efficiency was caused by re-entrainment of particles during the ESP operation. The effect of gas-flow velocity on the collection efficiency of the ESP was also investigated to study the cause of re-entrainment phenomena. The result showed that the re-entrainment phenomena depended on the gas-flow velocity     

Resolution of Epoxydienes by Reversed-Phase Chiral HPLC and its Application to Stereochemistry Assignment of Mulberry Looper Sex Pheromone

Resolution of insect pheromonal cis-epoxydiene racemates derived from (Z,Z,Z)-3,6,9-trienes was examined with a reversed-phase chiral HPLC column. The results showed that a Chiralcel OJ-R column was suitable for separating the enantiomers having a C₁₇–C₂₃ unsaturated straight chain except for 9,10-epoxydienes with a C₂₁–C₂₃ chain. To determine the absolute configuration of the separated enantiomers, each of the optically active epoxydienes was hydrogenated over Pd-BaSO₄ and its behavior was examined on this chiral column by cochromatography with the corresponding chiral epoxy compound having a saturated chain, which was prepared via a Sharpless epoxidation reaction. This analysis showed that the dextrorotatory C₁₇–C₂₃ 3,4- and 6,7-epoxydienes and C₁₇–C₂₀ 9,10-epoxydienes with shorter R _ts possess (3S,4R)-, (6S,7R)-, and (9R,10S) configurations, respectively, and the levorotatory enantiomers with longer R _ts possess the opposite configuration. An abdominal tip extract of the mulberry looper, Hemerophila artilineata Butler (Lepidoptera: Geometridae: Ennominae), included (9S,10R)-(Z,Z)-cis-9,10-epoxy-3,6-octadecadiene as a main sex pheromone component. The synthetic (9S,10R)-9,10-epoxydiene, rather than its antipode, elicited strong antennal and behavioral responses from the male moths in electrophysiological and field tests.     

On-line measurement of orientation development in the high-speed melt spinning process

On-line measurement of birefringence was performed in the high-speed melt spinning process of poly(ethylene terephthalate) using an apparatus that incorporates a rotating polarizer for the measurement of the optical retardation of running filament. Particular attention was paid to the detailed measurements in the vicinity of neck-like deformation. Through the measurement at the take-up velocity of 5 km/min, development of birefringence under the strain rate up to about 1 ms^?1 was investigated. To analyze the relation between applied stress and birefringence, tension and temperature profiles of the spin-line were calculated based on the experimentally obtained diameter profiles. Even though the strain rate is extremely high, a linear relationship between birefringence and a parameter calculated by dividing stress by temperature was confirmed to hold up to birefringence and stress/temperature values of about 0.017 and 10 kPa/K, respectively.     

Hot Isostatic Pressing of Reactive SnO2 Powder

Tin(IV) oxide (SnO₂) crystallizes at room temperature by adding hydrazine monohydrate ((NH₂)₂· H₂O) to a hydrochloric acid solution of tin, followed by washing and drying. Well-densified SnO₂ ceramics (99.8% of theoretical) with an average grain size of 0.9 μm have been fabricated by hot isostatic pressing for 2 h at 900°C and 196 MPa. Their Vickers hardness and bending strength are 14.4 GPa and 200 MPa, respectively. They exhibit an electrical conductivity of 2 × 10⁻³−9 × 10⁻³ S·cm⁻¹ at room temperature.     

Effect of Gallia Addition on the Sintering Behavior of Samaria-Doped Ceria

Samaria-doped ceria (SDC) was prepared by using the solid-state reaction method. Sintering of SDC was significantly promoted by adding a small amount of gallium. SDC that had 1% of gallium added, sintered at 1450°C, showed almost the same properties as SDC sintered at 1600°C. Measurements showed that the addition of gallia could reduce the sintering temperature by 150°C without deteriorating the properties of SDC as an electrolyte for solid oxide fuel cells.     

A Study of Polymer Electrolyte Fuel Cells by the Measurement of AC Impedance,Current Interrupt,and Dew Points: 2. Effect of Cell Temperature

The effect of cell temperature on the performance of a polymer electrolyte fuel cell was examined in the present study. Measurements using the current interrupt and AC impedance methods showed that membrane resistance increased as the cell temperature was reduced. The charge transfer resistance, determined by the AC impedance method, also increased with decreasing cell temperature. The results of electrochemical analysis showed that the temperature of the cell strongly affected the performance of the membrane–electrode assembly in the cell. In addition, the water balance calculated from dew points of fuel gases changed with cell temperature. At a cell temperature of 80 °C, ca. 80% of the water generated on the cathode passed through the membrane to the anode, while at a cell temperature of 40 °C, only ca. 20% of the water on the cathode passed through the membrane to the anode.     

Polyion Complex Fiber and Capsule Formed by Self‐Assembly of Chitosan and Poly(α,L‐glutamic acid) at Solution Interfaces

Different characteristic surface structures such as spherical capsules, regularly spaced droplets and fibers are formed by electrostatic polysaccharide interaction between chitosan and poly(α,L ‐glutamic acid) via polyion complex (PIC) formation. Spherical droplet‐like PIC capsules of varying diameters form in solutions. Some dyes adsorb on the surface of the capsules, while other dyes and benzoic acid derivatives penetrate into the capsules. The PIC fiber can be prepared by reactive‐spinning at the solution interface, followed by gravity and by removing water in ethanol. The tensile strength of the fiber is 11.2 kg·mm^–2 (1.48 g·denier^–1) and the knotting strength is 2.15 kg·mm^–2 (0.30 g·d^–1). By reaction with an organic cross‐linking agent, ethylene glycol diglycidyl ether (EGDE), the tensile strength of the fiber can be increased to 18.1 kg·mm^–2 (3.14 g·d^–1), and by reacting with hexamethylene diisocyanate (HMDI), the knotting strength of the fiber can be increased to 7.58 kg·mm^–2 (0.89 g·d^–1). The interaction energies (work of adsorption, W_ads) of PLG and chitosan in aqueous solution were estimated by a surface chemical approach, and a relationship between the W_ads values and the tensile strengths of the PIC fibers and the W_ads indicated that the higher W_ads system gives the higher tensile strength. The PIC fiber can be dyed by four different dyeing procedures such as direct and vat dyeings. When the cross‐linked PIC fiber was incubated in an aqueous solution in the presence of endocrine disruptor related compounds such as dibenzofuran and biphenyl, these compounds were accumulated onto and/or into the fibers.