A factorial design applied to polypropylene functionalization with maleic anhydride

Maleic anhydride functionalized PP was prepared in a melt-mixer according to a factorial design. Two levels of maleic anhydride concentration (MA), dicumyl peroxide concentration (DCP), reaction time, and temperature were employed. The isolated and interaction effects of these variables on the degree of functionalization and molecular weights were analyzed. The products were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), titration, and torque measures. The reaction time showed no appreciable effect within the studied range (10 to 20 minutes); however, the other three factors showed significant main effects. MA and temperature presented an important interaction effect on the degree of functionalization and molecular weights. The highest degrees of functionalization were found to be related to the smallest molecular weights.     

Simultaneous Disruption of Pheromone Communication in Choristoneura rosaceana and Pandemis limitata with Pheromone and Antagonist Blends

In British Columbia, trapping and wind-tunnel studies demonstrated that (Z)-9-tetradecenyl acetate (Z9–14:OAc), a minor component of the sex pheromone for Pandemis limitata, acted as a pheromone antagonist to a sympatric species, Choristoneura rosaceana. Addition of >1% Z9–14:OAc to the four-component C. rosaceana pheromone in a wind tunnel resulted in significant reductions in the proportion of male C. rosaceana that wing fanned, locked on to the plume in flight, oriented upwind, and made source contact, compared to the responses to the pheromone alone. Disruption of pheromone communication was tested in 33.3 × 33.3-m plots, at a release rate of 10 mg/ha/hr using Conrel fiber dispensers. Z9–14:OAc applied alone did not disrupt orientation to virgin-female-baited traps for either C. rosaceana or P. limitata. A 1:1 mixture of Z9–14:OAc and the four-component C. rosaceana pheromone was as effective as the pheromone alone at disrupting orientation of C. rosaceana males to virgin-female-baited traps, demonstrating that disruption apparently did not occur through false-trail following. The 1:1 mixture of Z9–14:OAc and the C. rosaceana pheromone also reduced catches of P. limitata males in virgin-female-baited traps, but not significantly more than the 83% disruption caused by the pheromone alone. Therefore, the C. rosaceana pheromone could be used alone or with Z9–14:OAc to disrupt communication and, presumably, mating in both leafrollers simultaneously.     

A Linear Discriminant for Gaussian Time Series

A simple linear discriminant is introduced for Gaussian time series with fixed deterministic component. It is demonstrated that the discriminant is 'efficient' under some general conditions. The proposed procedure is tested using some seismological data.     

U.v. irradiation-induced crosslinking of solid poly(ethylene oxide) modified with tetraalkyl ammonium salt

Crosslinked poly(ethylene oxide) (PEO) modified with a quaternary tetraalkyl ammonium salt, ethyl methacrylate dimethyldodecylammonium bromide, was prepared by exposure of the solid blend to ultraviolet radiation from a high-pressure 150 W mercury lamp. The photochemical crosslinking of the blends proceeded in the presence of benzophenone as a hydrogen-abstracting agent. Gel fraction yield exceeded 85%, equilibrium swelling in water varied from 3.0 to 5.0, and the equilibrium swelling in chloroform from 6.5 to 12.5. The networks obtained have been characterized by elemental analysis, i.r.,¹H n.m.r., and d.s.c. measurements and their microstructure, water absorption and equilibrium swelling have been discussed.     

The C-terminal domains of gammaS-crystallin pair about a distorted twofold axis

The 2-domain gammaS-crystallin, a highly conserved early evolutionaryoff-shoot of the gamma-crystallin family, is located in the water-richregion of eye lenses. The expressed C-terminal domain, gammaS-C, has beencrystallized and the 2.56 A X-ray structure determined. There are twodomains in the asymmetric unit which pair about a distorted twofold axis.One of the domains has an altered conformation in a highly conserved regionof the protein, the tyrosine corner. The distorted gammaS-C dimer ofdomains is compared with the highly symmetrical, equivalent recombinantdimer of C-terminal domains from gammaB- crystallin. Sequence changes closeto the interface, that distinguish gammaS from the other gamma-crystallins,are examined in order to evaluate their role in symmetrical domain pairing.     

Multiple steady states in combined buoyancy and wind driven natural ventilation: The conditions for multiple solutions and the critical point for initial conditions

Natural ventilation systems may have multiple steady states in the combined buoyancy and wind driven mode in a single space. In this paper, dynamical system analysis is applied both graphically and quantitatively to investigate the multiple steady state behavior of such a natural ventilation system.