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Olivier Véron Jean-Philippe Blondeau Michał Grabiec Aleksandra Wolak Krzystof Dzierżęga Nadège Ollier François Goutaland Mohamed Chérif Sow Stéphane Pellerin Nadia Pellerin 《Plasmonics (Norwell, Mass.)》2013,8(1):93-103
Silver-exchanged silicate glass has been irradiated by 532-nm pulsed Nd:YAG laser in order to locally form metallic nanoparticles. The particular interest of this process is to locally control the silver nanoparticles (NPs) growth. Silver ions are exchanged with sodium ions near the glass surface after dumping of a silicate glass few minutes in silver and sodium nitrates molten salt. A low-energy density laser exposure (0.239 J/cm2) chosen at the ablation threshold allows to observe the kinetics of the silver NPs growth according to the increasing shots number. An on-line optical measurement is carried out after each shot to identify the most important steps during the irradiation process. According to this measurement, we have determined four steps highlighted by UV/Visible spectrophotometry and we have identified the influence of located surface plasmon resonance. Three combined material analysis methods were used to understand the glass/laser interaction mechanism: we outlined the material volume variations by profilometric method, the element distribution by scanning electron microscopy and finally the structural distribution of the irradiated region by a local infrared investigation. The trend for NPs formation revealed by the UV/Visible spectrophotometry is thus explained by the formation of a ring expelled from a central hole. We highlight that the on-line extinction measurement can be used to data process the NPs evolution. 相似文献
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Helena Popławska Adam Wilczewski Agnieszka Dmitruk Wojciech Hołub 《Economics & Human Biology》2013,11(2):221-226
The aim of this study was to determine secular changes in the sexual maturation of children and adolescents from Eastern regions of Poland between 1980 and 2000, with special attention paid to rural–urban differences. Our sample comprised 34,055 girls and 28,100 boys from 9 to 18 years of age. The age at which each gender reached each stage of sexual maturation was examined, along with menarcheal age in girls. An increase in the rate of sexual maturation was observed over the 20-year period of this study. Menarcheal age in girls decreased by 0.59 years. The length of sexual maturation decreased: from 6.58 years to 3.85 years in girls and from 5.84 years to 3.65 years in boys. A significantly faster rate of sexual maturation was observed between 1990 and 2000. Over the entire 20-year period, adolescents living in rural settings experienced a slower rate of sexual maturation than did their urban peers. 相似文献
149.
Niels Van Steenkiste Bart Tessens Wim Willems Thierry Backeljau Ulf Jondelius Tom Artois 《PloS one》2013,8(3)
In this study we elaborate the phylogeny of Dalytyphloplanida based on complete 18S rDNA (156 sequences) and partial 28S rDNA (125 sequences), using a Maximum Likelihood and a Bayesian Inference approach, in order to investigate the origin of a limnic or limnoterrestrial and of a symbiotic lifestyle in this large group of rhabditophoran flatworms. The results of our phylogenetic analyses and ancestral state reconstructions indicate that dalytyphloplanids have their origin in the marine environment and that there was one highly successful invasion of the freshwater environment, leading to a large radiation of limnic and limnoterrestrial dalytyphloplanids. This monophyletic freshwater clade, Limnotyphloplanida, comprises the taxa Dalyelliidae, Temnocephalida, and most Typhloplanidae. Temnocephalida can be considered ectosymbiotic Dalyelliidae as they are embedded within this group. Secondary returns to brackish water and marine environments occurred relatively frequently in several dalyeliid and typhloplanid taxa. Our phylogenies also show that, apart from the Limnotyphloplanida, there have been only few independent invasions of the limnic environment, and apparently these were not followed by spectacular speciation events. The distinct phylogenetic positions of the symbiotic taxa also suggest multiple origins of commensal and parasitic life strategies within Dalytyphloplanida. The previously established higher-level dalytyphloplanid clades are confirmed in our topologies, but many of the traditional families are not monophyletic. Alternative hypothesis testing constraining the monophyly of these families in the topologies and using the approximately unbiased test, also statistically rejects their monophyly. 相似文献
150.
Anthony Arguelles Arias Marc Ongena Bart Devreese Mohammed Terrak Bernard Joris Patrick Fickers 《PloS one》2013,8(12)