ABSTRACT. As a proven tool, DNA barcoding can identify species rapidly and unambiguously. In this study, we used mtDNA cyt b, COI, and 16s rRNA sequences of six species of Pseudohynobius, Protohynobius puxiongensis, Liua shihi, Ranodon sibiricus, and Pachyhynobius shangchengensis, to reconstruct the phylogenetic relationships using Bayesian inference and maximum likelihood methods. Approximate lineage divergence times were also estimated, the divergence between them was calculated to have taken place mainly in Miocene. Our results showed that: 1) Ps. guizhouensis is an independent and valid species that is a sister species to Ps. kuankuoshuiensis; 2) five Pseudohynobius species formed a monophyletic group; 3) Ps. tsinpaensis is different from L. shihi, and should be classified as belonging to the Liua genus; and 4) Pr. puxiongensis is the sister lineage to all Pseudohynobius species, and should therefore be named Pseudohynobius puxiongensis.
With the development of the third generation synchrotron radiation sources the X-ray photoemission electron microscopy (XPEEM) is playing as a powerful tool for analyzing specimens with spatial resolution about tens of nanometer. It has been used to observe the chemical reaction process, and to investigate the surfaces, interfaces, thin films, buried layers and nano-structures. XPEEM image signals are contributed from photoelectrons, Auger electrons, backscattering electrons and secondary electrons excited by X-rays of certain energy. In this work, a Monte Carlo model for XPEEM image simulation is built. XPEEM images in total electron yield (TEY) mode are simulated with this model for several nanostructures (spheres and cylinders) of silver deposited on/in a silicon substrate (Ag/Si). The simulated XPEEM image in TEY mode for Ag dot array on a Si substrate is quite close to an experimental image. Furthermore, the XPEEM image simulation has been performed for different incident X-rays and for different geometric structures.
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