The melts of a series of low molecular weight poly（ethylene oxide）（PEO） fractions on mica surfaces were studied by atomic force microscopy（AFM） and X-ray reflectivity（XRR） measurement.The PEO ultrathin films w...The melts of a series of low molecular weight poly（ethylene oxide）（PEO） fractions on mica surfaces were studied by atomic force microscopy（AFM） and X-ray reflectivity（XRR） measurement.The PEO ultrathin films were obtained via static dilute solution casting.Different from the melts of the PEO with both methoxyl（（—OCH3）） end groups that are dewetted on the mica surface,a pseudo-dewetting phenomenon of the PEO melts was observed when either one end group of the PEOs becomes hydroxyl（—OH） or both are hydroxyl groups.The wetting layer thicknesses of the pseudo-dewetted melts were measured to be 4.5～4.7 nm,independent on the molecular weight and the end groups of PEOs.However,the PEO melt droplets on the wetting layer varied from spherical caps with relatively high contact angle to irregular shapes with relatively low contact angle when increasing the molecular weight and the hydrophobicity of end groups of PEOs.展开更多
This work evaluates the phenotypic response of the model grass （Brachypodium distacbyon （L.） P. Beauv.） to nitrogen and phosphorus nutrition using a combination of imaging techniques and destructive harvest of sho...This work evaluates the phenotypic response of the model grass （Brachypodium distacbyon （L.） P. Beauv.） to nitrogen and phosphorus nutrition using a combination of imaging techniques and destructive harvest of shoots and roots. Reference line Bd21-3 was grown in pots using 11 phosphorus and 11 nitrogen concentrations to establish a dose-response curve. Shoot biovolume and biomass, root length and biomass, and tissue phosphorus and nitrogen concentrations increased with nutrient concentration. Shoot biovolume, estimated by imaging, was highly correlated with dry weight （R2 〉 0.92） and both biovolume and growth rate responded strongly to nutrient availability. Higher nutrient supply increased nodal root length more than other root types. Photochemical efficiency was strongly reduced by low phosphorus concentrations as early as 1 week after germination, suggesting that this measurement may be suitable for high throughput screening of phosphorus response. In contrast, nitrogen concentration had little effect on photochemical efficiency. Changes in biovolume over time were used to compare growth rates of four accessions in response tonitrogen and phosphorus supply. We demonstrate that a time series image-based approach coupled with mathematical modeling provides higher resolution of genotypic response to nutrient supply than traditional destructive techniques and shows promise for high throughput screening and determina- tion of genomic regions associated with superior nutrient use efficiency.展开更多
文摘The melts of a series of low molecular weight poly（ethylene oxide）（PEO） fractions on mica surfaces were studied by atomic force microscopy（AFM） and X-ray reflectivity（XRR） measurement.The PEO ultrathin films were obtained via static dilute solution casting.Different from the melts of the PEO with both methoxyl（（—OCH3）） end groups that are dewetted on the mica surface,a pseudo-dewetting phenomenon of the PEO melts was observed when either one end group of the PEOs becomes hydroxyl（—OH） or both are hydroxyl groups.The wetting layer thicknesses of the pseudo-dewetted melts were measured to be 4.5～4.7 nm,independent on the molecular weight and the end groups of PEOs.However,the PEO melt droplets on the wetting layer varied from spherical caps with relatively high contact angle to irregular shapes with relatively low contact angle when increasing the molecular weight and the hydrophobicity of end groups of PEOs.
基金supported by the Office of Science (BER), U.S. Department of Energy through Interagency Agreement DE-SC0001526the Australian Grain Research and Development Corporation (GRDC)
文摘This work evaluates the phenotypic response of the model grass （Brachypodium distacbyon （L.） P. Beauv.） to nitrogen and phosphorus nutrition using a combination of imaging techniques and destructive harvest of shoots and roots. Reference line Bd21-3 was grown in pots using 11 phosphorus and 11 nitrogen concentrations to establish a dose-response curve. Shoot biovolume and biomass, root length and biomass, and tissue phosphorus and nitrogen concentrations increased with nutrient concentration. Shoot biovolume, estimated by imaging, was highly correlated with dry weight （R2 〉 0.92） and both biovolume and growth rate responded strongly to nutrient availability. Higher nutrient supply increased nodal root length more than other root types. Photochemical efficiency was strongly reduced by low phosphorus concentrations as early as 1 week after germination, suggesting that this measurement may be suitable for high throughput screening of phosphorus response. In contrast, nitrogen concentration had little effect on photochemical efficiency. Changes in biovolume over time were used to compare growth rates of four accessions in response tonitrogen and phosphorus supply. We demonstrate that a time series image-based approach coupled with mathematical modeling provides higher resolution of genotypic response to nutrient supply than traditional destructive techniques and shows promise for high throughput screening and determina- tion of genomic regions associated with superior nutrient use efficiency.
