3,134 publications from this institution
We have observed that in complex nanostructures, such as pairs of nanorods, hotspots of optical emission induced by electron-beam excitation exist at their point of closest proximity, where strong local field enhancements are expected.
Abstract A rapid revised phase high‐performance liquid chromatographic (RP‐HPLC) method for the determination of six organic acids in Bayer liquors is reported. Oxalic, tartaric, acetic, succinic, glutaric and butene dicarboxylic acid were separated and quantified in 10 min. First time repeatability, reproducibility and recoveries were determined out for these acids in Bayer liquors. The organic acids were removed from Bayer liquor by using a solid‐phase extraction procedure with anion‐exchange cartridges. The chromatographic separation was achieved with only one Kromasil RP‐C 18 column thermo stated at 25 °C. Organic acids were detected with a UV–vis detector (215 nm). The precision results showed that the relative standard deviations of the repeatability and reproducibility were <2.80% and <3.74%, respectively. The accuracy of the method was confirmed with an average recovery ranging between 85.2 and 107.3%. Under optimum conditions the detection limits ranged from 50 to 1000 mg/L.
Summary Divergent artificial selection for abdominal bristle number in Drosophila melanogaster has been carried out starting from a genetically homogeneous base population. Lines with two different systems of mating, random ( P lines) or between full sibs whenever possible (about 50%), random otherwise ( I lines) were compared. Responses after 40 generations of selection were mostly due to one or two mutations of large effect (0·2 to 2 phenotypic standard deviations) per line. Ten mutations affecting the selected trait were individually studied (five lethal and five non-lethal, these being predominantly additive). These mutations satisfactorily explain the response attained, although some minor mutations may also be involved. No evidence of epistasis for bristle number was found. The average final divergence was 57% larger in the P lines, but it was mostly due to lethals or highly deleterious mutations. Thus, after relaxation of selection, the ranking reversed and the mean divergence became significantly larger in the I lines (14%). Analysis of inbreeding showed that the very small amount of variation created by spontaneous mutations (a heritability for the selected trait of about 3%) was responsible for a reduction in the effective size of about 50% in the I lines (relative to the case with random selection), but only about 10% in the P lines. Mutational heritabilities estimated from the response to selection (0·05–0·18%) were within the range usually found for this trait in previous experiments. REML estimates account for correlations between relatives, and were much larger in those lines where the response was due to lethal mutations, as these do not contribute to response after reaching maximum frequency.
