Development of anion-conducting ionomer binder solutions for electrodes of solid alkaline fuel cells.

For solid alkaline fuel cell applications, membrane-electrode assemblies (MEAs) should be prepared. Thus, in this study, anion-conducting ionomer binder was prepared for electrodes of MEAs. Specifically, we synthesized water soluble anionic binder solutions based on quaternized chitosan derivatives (QCDs) and cross-linked QCDs and prepared a novel electrode. The electrochemical and physicochemical properties of ionomer binder and electrode were investigated by FT-IR, NMR and ionic conductivity. The ionic conductivity of these cross-linked QCDs was 9.7 x 10(-3) S cm(-1) in deionized water at room temperature. The membrane electrode assemblies (MEAs) were prepared by a spray method and were investigated in terms of cyclic voltammetry, impedance and fuel cell performance. The MEA with the 35 wt% QCD ionomer showed the highest performance and confirmed the successful formation of ionomer binder at the electrode of the MEA by the on-site crosslinking reaction.

Development of breeding lines with three pyramided resistance genes that confer broad-spectrum bacterial blight resistance and their molecular analysis in rice.

BACKGROUND: The development of resistant cultivars has been the most effective and economical strategy to control bacterial leaf blight (BB) disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo). Molecular markers have made it possible to identify and pyramid valuable genes of agronomic importance in resistance rice breeding. In this study, three resistance genes (Xa4 + xa5 + Xa21) were transferred from an indica donor (IRBB57), using a marker-assisted backcrossing (MAB) breeding strategy, into a BB-susceptible elite japonica rice cultivar, Mangeumbyeo, which is high yielding with good grain quality. RESULTS: Our analysis led to the development of three elite advanced backcross breeding lines (ABL) with three resistance genes by foreground and phenotypic selection in a japonica genetic background without linkage drag. The background genome recovery of the ABL expressed more than 92.1% using genome-wide SSR marker analysis. The pathogenicity assays of three resistance-gene-derived ABL were conducted under glasshouse conditions with the 18 isolates of Xoo prevalent in Korea. The ABL exhibited very small lesion lengths, indicating a hypersensitive reaction to all 18 isolates of Xoo, with agronomic and grain quality traits similar to those of the recurrent parent. Pyramiding the resistance genes Xa4, xa5 and Xa21 provided a higher resistance to Xoo than the introduction of the individual resistance genes. Additionally, the combination of two dominant and one recessive BB resistance gene did not express any negative effect on agronomic traits in the ABL. CONCLUSIONS: The strategy of simultaneous foreground and phenotypic selection to introduce multiple R genes is very useful to reduce the cost and the time required for the isolation of desirable recombinants with target resistance genes in rice. The resistance-gene-derived ABL have practical breeding value without a yield penalty by providing broad-spectrum resistance against most of the existing isolates of BB in South Korea and will have a high impact on the yield stability and sustainability of rice productivity.

Interactions between multiwall carbon nanotubes and poly(diallyl dimethylammonium) chloride: effect of the presence of a surfactant.

The interactions between multiwall carbon nanotubes (MWCNTs) and poly(diallyl dimethylammonium) chloride (PDDA) have been studied in the presence of different ionic and nonionic surfactants, such as sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), Tween 20, 40, 60, and 80, and Triton X-100. On the basis of scanning electron microscopy (SEM) results, the MWCNT/PDDA sample treated with Triton X-100 has been observed to show good dispersion of nanotubes. This is due to the π-π stacking between the benzene ring of Triton X-100 and the hexagonal carbon rings of nanotubes and better coating of PDDA on MWCNTs, as is confirmed by the Raman studies. Energy dispersive X-ray (EDX) spectroscopic data shows the presence of higher oxygen content in the MWCNTs/PDDA/Triton X-100 sample. The maximum upshift in the C1s peak position and down-shift in the N1s peak position for the MWCNTs/PDDA/Triton X-100 sample has been observed from X-ray photoelectron spectroscopy (XPS) results and is due to the intermolecular charge transfer from carbon in MWCNTs to nitrogen in PDDA. The presence and nature of a surfactant in the MWCNTs/PDDA system has been found to affect their interactions. The above results suggest that the MWCNTs/PDDA/Triton X-100 system is suitable as a metal-free electrocatalyst for the oxygen reduction reaction (ORR) in fuel cells.

A study on the effect of different chemical routes on functionalization of MWCNTs by various groups (-COOH, -SO3H, -PO3H2).

Pristine multiwall carbon nanotubes [MWCNTs] have been functionalized with various groups (-COOH, -SO3H, -PO3H2) using different single- and double-step chemical routes. Various chemical treatments were given to MWCNTs using hydrochloric, nitric, phosphoric, and sulphuric acids, followed by a microwave treatment. The effect of the various chemical treatments and the dispersion using a surfactant via ultrasonication on the functionalization of MWCNTs has been studied. The results obtained have been compared with pristine MWCNTs. Scanning electron microscopy, energy dispersive X-ray [EDX] spectroscopy, and transmission electron microscopy confirm the dispersion and functionalization of MWCNTs. Their extent of functionalization with -SO3H and -PO3H2 groups from the EDX spectra has been observed to be higher for the samples functionalized with a double-step chemical route and a single-step chemical route, respectively. The ID/IG ratio calculated from Raman data shows a maximum defect concentration for the sample functionalized with the single-step chemical treatment using nitric acid. The dispersion of MWCNTs with the surfactant, Triton X-100, via ultrasonication helps in their unbundling, but the extent of functionalization mainly depends on the chemical route followed for their treatment. The functionalized carbon nanotubes can be used in proton conducting membranes for fuel cells.