Polymer blends based on sulfonated poly(ether ketone ketone) and poly(ether sulfone) as proton exchange membranes for fuel cells,

Abstract The importance of the blend microstructure and its effect on conductivity and structural integrity of proton exchange membranes (PEM) were investigated. Sulfonated poly(ether ketone ketone) (SPEKK) was selected as the proton-conducting component in a blend with either poly(ether sulfone) (PES) or SPEKK with a different sulfonation level. The second component was added to improve the mechanical stability in the fuel cell environment. Membranes were cast from solution using N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc). Special attention was paid to the ternary solution behavior. Solution cast SPEKK/PES membranes are homogeneous for all studied compositions, 8/2 through 5/5 (w/w), and sulfonation levels, 1.7-3.5 mequiv./g. Although this polymer pair does not show evidence for intrinsic compatibility, the excellent solvent quality results in a frozen-in structure during solution casting. The morphology of SPEKK/SPEKK blends can be tailor-made by finding the right balance between composition, casting solvent and temperature. Co-continuous morphologies can be devised for an SPEKK blend with sulfonation levels of 1.2 and 2 mequiv./g. Both blends show lower swelling than the parent SPEKK. This results in better stability of PEMs during fuel cell testing

Magazines for youth? : a comparative content analysis of two New Zealand juvenile periodicals

This research project investigated the readership of two New Zealand youth magazines during the period 1945-1947. The magazines, Conquest: the magazine for youth, and Junior Digest: the magazine for girls and boys, were subjected to a content analysis which attempted to capture details of the readers, and describe the types of articles in each magazine in an attempt to discover what kinds of reading tastes young people of the period had. The project produced a description of the kinds of content that were present in the two magazines and in what quantities. By combining this content analysis with demographic data of the readers themselves, who contributed to the magazines by sending letters, jokes, competition entries and jokes, this research was able to show who the specific group of readers were and make conclusions about what they liked. By contrasting the results, it was determined that there were slight differences in the content of the magazines which may have accounted for the failure of Conquest to continue after July 1947, but that the data provided by the content analysis alone was insufficient to allow insight into the broader periodical reading tastes of New Zealand youth in the second half of the 1940s

Trapping \u3ci\u3ePhyllophaga \u3c/i\u3espp. (Coleoptera: Scarabaeidae: Melolonthinae) in the United States and Canada using sex attractants.

The sex pheromone of the scarab beetle, Phyllophaga anxia, is a blend of the methyl esters of two amino acids, L-valine and L-isoleucine. A field trapping study was conducted, deploying different blends of the two compounds at 59 locations in the United States and Canada. More than 57,000 males of 61 Phyllophaga species (Coleoptera: Scarabaeidae: Melolonthinae) were captured and identified. Three major findings included: (1) widespread use of the two compounds [of the 147 Phyllophaga (sensu stricto) species found in the United States and Canada, males of nearly 40% were captured]; (2) in most species intraspecific male response to the pheromone blends was stable between years and over geography; and (3) an unusual pheromone polymorphism was described from P. anxia. Populations at some locations were captured with L-valine methyl ester alone, whereas populations at other locations were captured with L-isoleucine methyl ester alone. At additional locations, the L-valine methyl ester-responding populations and the L-isoleucine methyl ester-responding populations were both present, producing a bimodal capture curve. In southeastern Massachusetts and in Rhode Island, in the United States, P. anxia males were captured with blends of L-valine methyl ester and L-isoleucine methyl ester

Preparation Via Supercritical Fluid Route Of Pd-Impregnated Nafion Membranes Which Exhibit Reduced Methanol Crossover For Dmfc

Palladium (Pd)-impregnated Nafion membranes that reduce methanol crossover were synthesized via a supercritical fluid route. The method involved impregnation of Nafion membranes with palladium(II) hexafluoroacetylacetonate from a supercritical CO2 (scCO2) solution, followed by subjecting the impregnated membranes to hydrogen. Membrane morphology was characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The obtained membranes had uniform surface morphology. The palladium particles were distributed both at the membrane surface and also extended deeper into the membrane. Membrane electrode assemblies with palladinized Nafion membranes were prepared and evaluated in direct methanol fuel cells (DMFCs) to determine methanol crossover, proton conductivity as well as DMFC performance. The Pdimpregnated Nafion membranes showed reduced methanol crossover and gave improved DMFC performance compared to that of a pure Nafion membrane, especially with higher concentration of methanol such as 5 M. The suppressed methanol crossover of Nafion membranes by the palladium impregnation improved DMFC efficiency. The successful preparation of palladium-impregnated membranes through the scCO2 route demonstrated an effective alternative way for modifying membranes and for depositing electrode catalytic nanoparticles onto electrolyte. © 2005 The Electrochemical Society. All rights reserved

Susceptibility of four species of turfgrass-infesting scarabs (Coleoptera: Scarabaeidae) to Bacillus thuringiensis serovar japonensis strain Buibui

Bacillus thuringiensis serovar japonensis strain Buibui experimental formulations containing Cry8Cal δ-endotoxin were evaluated in the field for the control of oriental beetle, Anomala orientalis Waterhouse; Japanese beetle, Popillia japonica Newman; Asiatic garden beetle, Maladera castanea (Arrow); and European chafer, Rhizotrogus majalis (Razoumowsky) larvae infesting turfgrasses. In 17 fall applications, control of A. orientalis and P. japonica was achieved at rates as low as 100 g of toxin per ha; however, rates of 301 or 593 g/ha were consistently more effective. A. orientalis larvae were the most susceptible followed by P. japonica, R. majalis, and M. castanea. Two spring applications of 120 g of toxin per ha were not effective against oriental or Japanese beetles. © 2007 Entomological Society of America

Membranes And Meas Based On Sulfonated Poly(Ether Ketone Ketone) And Heteropolyacids For Polymer Electrolyte Fuel Cells

Organic sulfonated poly(ether ketone ketone) (SPEKK) membranes with different ion-exchange capacities (IECs), and composite membranes prepared by the addition of 20 wt % phosphotungstic acid (PTA) to SPEKK were used to prepare membrane electrode assemblies (MEAs). The proton conductivity of the membranes increased with increasing IEC of the SPEKK, and with the addition of PTA. The proton conductivity attained at 80°C and 75% relative humidity was 20±2 mS/cm. The feasibility of using SPEKK in the cathode layer of the MEAs was investigated. The electrochemically active surface areas (ECAs) of the SPEKK-based cathodes were lower than that of the Nafion-based cathode and decreased further as the operating relative humidity was lowered. These observations were reflected in the single-cell polarization data, which indicated that the MEAs with the SPEKK-based electrodes were outperformed by their Nafion-based counterparts. Furthermore, a mismatch in SPEKK IEC between the membrane and cathode resulted in immiscibility at the interface. While the additive stability in the composite membrane was very good, the long-term stability of the membranes was poor when compared to perfluorosulfonic acid membranes such as Nafion, with failure occurring by scission along the gasket edges of the MEA after limited operation. © 2008 The Electrochemical Society