Ethylene and 1‐hexene sorption in LLDPE under typical gas‐phase reactor conditions: Experiments

The sorption of ethylene and 1‐hexene and their mixture in three poly(ethylene‐co‐1‐hexene) samples is measured gravimetrically at temperatures 70, 90, and 150°C and pressures 0–30 bar. Gravimetric sorption measurements are supplemented with microscopic observations of swelling of polyethylene particles caused by sorption and the extent of swelling is found to be significant. Experimental data are compared with predictions of PC‐SAFT (perturbed chain—‐statistical associating fluid theory) equation of state. Comparison of sorption data in semicrystalline polymer (measured at 70 and 90°C) and amorphous polymer (at 150°C) demonstrates the constraining effect of semicrystalline structure. Solubilities of penetrants in investigated samples are not observed to depend on the content of 1‐hexene in copolymers. The solubility of the mixture of ethylene and 1‐hexene is smaller than the sum of solubilities of individual components at 70 and 90°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1124–1136, 2006     

Identification of a Widespread Monomolecular Odor Differentially Attractive to Several <Emphasis Type="Italic">Delia Radicum</Emphasis> Ground-dwelling Predators in the Field

Dimethyl disulfide (DMDS) was identified as a major volatile constituent of Brassica napus roots heavily infested by Delia radicum, the cabbage root fly. Attractiveness of this widespread compound was tested in the field in a naturally complex odorous environment. By using an original setup especially designed for ground dwelling beetles, different concentrations of the pure molecule as well as attractiveness of the natural blend emitted by the rotten part of infested roots were tested simultaneously. The use of general linear model (GLM) statistics permitted us to finely discriminate the responses among the different treatments. The main predators of D. radicum (i.e., two staphylinids Aleochara bilineata and Aleochara bipustulata and carabid beetles of the genus Bembidion) were significantly attracted by DMDS, but responded in different ways to the natural blend and to the different concentrations tested. The dose–response curves were similar for the two staphylinids. However, whereas A. bilineata was more attracted by the natural volatile blend than by its preferred DMDS concentration, A. bipustulata was attracted as much by the natural blend as by its preferred DMDS concentration. Carabid beetles exhibited a different response. They were not attracted by the natural blend, but responded to a wider range of DMDS concentrations that included low concentrations that did not attract the staphylinid beetles. These results are discussed according to the potential resources searched by each taxon studied and their specificity for the resources. The possible use of DMDS for enhancing biological control of D. radicum is mentioned.     

Stabilization/solidification of munition destruction waste by asphalt emulsion

Destruction of discarded military munitions in an explosion chamber produces two fractions of hazardous solid waste. The first one is scrap waste that remains in the chamber after explosion; the second one is fine dust waste, which is trapped on filters of gas products that are exhausted from the chamber after explosion. The technique of stabilization/solidification of the scrap waste by asphalt emulsion is described in this paper. The technique consists of simple mixing of the waste with anionic asphalt emulsion, or two-step mixing of the waste with cationic asphalt emulsion. These techniques are easy to use and the stabilized scrap waste proves low leachability of contained heavy metals assessed by TCLP test. Hence, it is possible to landfill the scrap waste stabilized by asphalt emulsion. If the dust waste, which has large specific surface, is stabilized by asphalt emulsion, it is not fully encapsulated; the results of the leaching tests do not meet the regulatory levels. However, the dust waste solidified by asphalt emulsion can be deposited into an asphalted disposal site of the landfill. The asphalt walls of the disposal site represent an efficient secondary barrier against pollutant release.     

Expansion of Access Tunnels and Active‐Site Cavities Influence Activity of Haloalkane Dehalogenases in Organic Cosolvents

The use of enzymes for biocatalysis can be significantly enhanced by using organic cosolvents in the reaction mixtures. Selection of the cosolvent type and concentration range for an enzymatic reaction is challenging and requires extensive empirical testing. An understanding of protein–solvent interaction could provide a theoretical framework for rationalising the selection process. Here, the behaviour of three model enzymes (haloalkane dehalogenases) was investigated in the presence of three representative organic cosolvents (acetone, formamide, and isopropanol). Steady‐state kinetics assays, molecular dynamics simulations, and time‐resolved fluorescence spectroscopy were used to elucidate the molecular mechanisms of enzyme–solvent interactions. Cosolvent molecules entered the enzymes' access tunnels and active sites, enlarged their volumes with no change in overall protein structure, but surprisingly did not act as competitive inhibitors. At low concentrations, the cosolvents either enhanced catalysis by lowering K_0.5 and increasing k_cat, or caused enzyme inactivation by promoting substrate inhibition and decreasing k_cat. The induced activation and inhibition of the enzymes correlated with expansion of the active‐site pockets and their occupancy by cosolvent molecules. The study demonstrates that quantitative analysis of the proportions of the access tunnels and active‐sites occupied by organic solvent molecules provides the valuable information for rational selection of appropriate protein–solvent pair and effective cosolvent concentration.     

A study on electrical and thermal conductivities of ethylene–octene copolymer/expandable graphite composites

A series of ethylene–octene copolymer (EOC) composites have been prepared by melt‐mixing with different weight ratios of expandable graphite filler (0–50% by weight). Electrical conductivity [both alternating current (AC) and direct current (DC)] and thermal conductivity studies were carried out. Effect of filler loading and frequency on electrical conductivity was studied. DC conductivity has increased from 1.51 × 10^?13 S cm^?1 to 1.17 × 10^?1 S cm^?1. Percolation threshold by DC and also AC methods was observed at about 16 vol% of the filler. Real part of permittivity was found to be decreasing with increase in frequency while conductivity was increasing. Thermal conductivity was also found to be increasing gradually from 0.196 to 0.676 Wm^?1 K^?1 which is about 245% increase. Graphite not only increases the electrical and thermal conductivities but at and above 40 wt%, also acts as a halogen‐free, environmental friendly flame retardant. Shore‐A hardness of EOC/graphite composites shows that even with high graphite loading, the hardness is increased from about 50–68 only so that the rubbery nature of the composite is not affected very much. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Adaptation of the musical composition method for solving constrained optimization problems

Many real-world problems may be expressed as nonlinear constrained optimization problems (CNOP). For this kind of problems, the set of constraints specifies the feasible solution space. In the last decades, several algorithms have been proposed and developed for tackling CNOP. In this paper, we present an extension of the “Musical Composition Method” (MMC) for solving constrained optimization problems. MMC was proposed by Mora et al. (Artif Intell Rev 1–15, doi:10.1007/s10462-011-9309-8, 2012a). The MMC is based on a social creativity system used to compose music. We evaluated and analyzed the performance of MMC on 12 CNOP benchmark cases. The experimental results demonstrate that MMC significantly improves the global performances of the other tested metaheuristics on some benchmark functions.