Vacuum Ultraviolet Spectra of Silver in a Borosilicate Glass

Vacuum ultraviolet absorption spectra of silver dissolved in 60 mol% B₂O₃-40 mol% SiO₂ glass in oxygen, nitrogen, and oxygen–nitrogen atmospheres at 1000°, 1100°, and 1200°C were measured. Strong absorption which may be attributed to Ag⁺-complex was observed around 5.5 and 6.5 eV. It is suggested that an Ag⁺-complex/Ag⁰ redox pair exists in the glass and that this pair shows O-type redox behavior.     

Growth of NiWO4 crystals from a Na2W2O7 flux

Well-formed rod crystals of NiWO₄ were grown from a Na₂W₂O₇ flux by a slow cooling method. The solubility of NiWO₄ in Na₂W₂O₇ increased with increasing temperature. At 1100 °C, NiWO₄ was dissolved in Na₂W₂O₇ at a concentration of about 45 mol %. The eutectic temperature was 615± 5 °C. Flux growth was conducted by heating mixtures at 1100 °C for 10 h, followed by cooling to 500 °C at a rate of 5 °C h^–1. The brownish and transparent crystals up to 15 mm in length were grown from the mixtures of about 40 g. The most suitable solute content was 30 mol %. The grown crystals were bounded by the {100}, {010}, {110}, {102}, and {111} faces. In certain instances, the {111} faces disappeared. The EPMA data showed that sodium from the flux used was not contained within the grown crystals. The crystals of NiWO₄ had a d.c. electrical resistivity of about 1 × 10¹¹ cm.     

Mechanism of bed-wall heat transfer in a fluidized bed at high temperatures

Radiant heat transfer in a fluidized bed was investigated experimentally by means of two kinds of heat exchange pipes. It was found that the contribution due to radiant heat transfer would be insignificant at temperature levels in fluidized beds up to 1000°C.The results are interpreted in terms of a model based on the behaviour of bubbles in the fluidized bed.     

Correlation of normal stresses in polystyrene melts and its implications

It is found that the principal normal stress difference, N₁, in commercial polystyrene melts is a unique function of shear stress σ₁₂, independent of temperature and molecular weight, An empirical expression representing this relationship is developed. The functional dependence reported does not represent data for narrow molecular weight distribution polystyrenes, generally significantly overpredicting N₁ values. The basis for this behavior is discussed. The implications of the N₁ ? σ₁₂ relationship to some rheological and processing problems are described.     

Jetting phenomena in injection mold filling mold filling

Experimental studies of injection molding of polymer melts have classified two regimes of mold filling–simple filling and jetting. In this paper we have examined a wide range of polymer melts and mold designs in an attempt to devise a criterion for the transition between these regimes. This criterion is found to be related to the extrudate swell d, gate diameter D, and small cavity dimension at the gate h. For isothermal mold filling, if d/h exceeds 1.0, the-melt will contact the mold, stick to it, and induce a simple mold filling regime. The variation in behavior in vertical and horizontal mold filling is considered, as is the influence of barriers near the gate. For the non-isothermal mold case, the manner of filling is similar, and the criterion for jetting remains the same, The die swell behavior in the non-isothermal case is complex.     

Stabilization of poly(vinyl chloride). VIII. Synergisms between epoxy compounds and metal soaps

Effects of bisphenol A type epoxy compounds involving various average molecular weights on the zinc stearate/calcium stearate and the cadmium stearate/barium stearate synergetic soaps induced thermal stabilization of poly(vinyl chloride) (PVC) were investigated by colorimetry. The remarkable stabilization effects of epoxides could not be observed on the PVC films without synergetic soaps, while the stabilization of PVC was markedly enhanced by combined use of epoxides and synergetic soaps. The appearance of excessive coloration of cool color producing metal chloride–polyene complexes which were an origin of abrupt discoloration of stabilized PVC was retarded by using epoxides together with synergetic soaps. Moreover, as for PVC with or without synergetic soaps, the epoxy compounds did not inhibit the formation of longer polyene chains which were a chromophore for yellow orange of aged PVC. Further colorimetries and IR or X-ray photoelectron spectroscopies on the various PVC containing epoxy compounds and zinc chloride indicated that the epoxy groups caught the zinc chloride. The synergetic effect between epoxy compounds and synergetic metal soaps is ascribed to the action that the epoxides serve as an acceptor for the excessive cool color producing metal chloride produced from zinc stearate and cadmium stearate to retard the abrupt discoloration of stabilized PVC.     

Lasioderma chemistry sex pheromone of cigarette beetle (Lasioderma serricorne F.)

A chemical study of the sex pheromone of the cigarette beetle was carried out. Seven components were isolated from active fractions of column chromatography of the female extract, and their structures were elucidated by spectroscopic evidence and confirmed by synthesis to be (4S,6S,7S)-4,6-di-methyl-7-hydroxynonan-3-one (serricornin) (I), 2,6-diethyl-3,5-dimethyl-3,4-dihydro-2H-pyran (anhydroserricornin) (II), 4,6-dimethylnonan-3,7-dione (III), 4,6-dimethylnonan-3,7-diol (IV), 4,6-dimethyl-7-hydroxy-4-nonen-3-one (V), (2S,3R)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(l-methyl-2-oxobutyl)-4H-pyran-4-one (serricorone) (VI) and (2S,3R)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(1-methyl-2-hydroxybutyl)-4H-pyran-4-one (serricorole) (VII).These structural features suggested that the occurrence of these components might be related to the polyketide biosynthesis. The behavioral bioassay and BAG experiments revealed the biological role of each component in the copulatory behavior of this insect.     

High-temperature 1H n.m.r. study of oxidized coal

Two coking coals, a caking and a non-caking coal are examined in a Bruker pulsed ¹H n.m.r. spectrometer in the temperature range 293–730 K. One coking and the caking coal are oxidized in air at 383 K for 13 days. Temperatures of signal appearance and loss are noted as well as the temperatures of minimum signal half-peak width ($\text{ΔH}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$). There occurs no change in the above three temperatures with oxidation of the coals. The variation of ($\text{ΔH}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$) with temperature of the coal is also measured. Changes in ($\text{ΔH}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$) are more pronounced for the caking coal. The softening and solidification temperatures are below and above, respectively, those reported using the Gieseler method. Values of ($\text{ΔH}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$) increase beyond the minimum value as the fluidity continues to increase. This may be caused by an increase in average molecular weight of constituent molecules and/or an increasing concentration of free radicals in the fluid phase. This experimental approach may afford a new method to characterize coals which are to be used in liquefaction processes.