In this work, p-MoO3 nanostructures/n-TiO2 nanofiber heterojunctions (p-MoO3/n-TiO2-NF-HJs) were obtained by a two-step fabrication route. First, MoO2 nanostructures were hydrothermally grown on electrospun TiO2 nanofibers. Second, by thermal treatment of the obtained MoO2 nanostructures/TiO2 nanofibers, p-MoO3/n-TiO2-NF-HJs were obtained due to the phase transition of MoO2 to MoO3. With increasing the concentration of molybdenum precursor in hydrothermal process, the morphologies of MoO2 changed from nanoparticles to nanosheets, and then fully covered shells with an increased loading on TiO2 nanofibers. After calcination, the obtained p-MoO3/n-TiO2-NF-HJs possessed similar morphology to that without thermal treatment. X-ray photoelectron spectra showed that both Ti 2p and OTi-O 1s peaks of p-MoO3/n-TiO2-NF-HJs shifted to higher binding energies than that of TiO2 nanofibers, suggesting electron transfer from TiO2 to MoO3 in the formation of p-n nanoheterojunctions. The p-n nanoheterojunctions decreased photoluminescence intensity, suppressed photogenerated electrons and holes recombinations, and enhanced charge separation and photocatalytic efficiencies. The apparent first-order rate constant for the degradation of RB by p-MoO3/n-TiO2-NF-HJs with nanosheets surface morphology was two times that of TiO2 nanofibers. For the core/shell structure of p-MoO3/n-TiO2-NF-HJs, the internal electric field of p-n junction forced the photogenerated electrons transferring to TiO2 cores, then decreased the surface photocatalytic reactions and led to the lowest photocatalytic activity among the p-MoO3/n-TiO2-NF-HJs.

Information on population genetics is fundamental to developing in situ or ex situ conservation strategies. Few researchers, however, have compared the genetic structure of restored and natural populations of threatened plant species. Metasequoia glyptostroboides Hu & Cheng (dawn redwood) (Taxodiaceae), a living fossil endemic to China, may be the most successfully recovered threatened species, with many more individuals and a much wider distribution than fossil records indicate. We used random amplification of polymorphic DNA markers to compare the genetic structure of artificial populations with that of wild ones and to determine whether the genetic structure of M. glyptostroboides has been recovered as has its distribution. The genetic variation of wild populations of M. glyptostroboides was lower than the average of gymnosperms, indicating the effects of glaciations and recent habitat loss and fragmentation. Genetic variation in artificial populations was less, but not substantially, compared with wild populations. The unweighted pair group method with arithmetic mean revealed that the wild and the artificial populations formed two distinct groups. Artificial populations were more similar to each other (mean Nei's genetic distance = 0.0924) than to wild populations (mean distance = 0.2054). This might be the result of biased seed collection, vegetative propagation, or a mixture of propagules from different populations and an ultimate propagule source. These results suggest that although the quantity and distribution range have been successfully restored, the genetic structure of M. glyptostroboides has not recovered appropriately, given the loss of genetic variation and biased genetic composition in artificial populations. Therefore, in addition to protecting the wild populations, additional ex situ genetic reserves should be established based on genetic knowledge and via appropriate approaches. We suggest that population genetic and demographic indices should be considered when downlisting or delisting threatened species.Resumen: Es fundamental contar con información sobre genética poblacional para el desarrollo de estrategias de conservación in situ o ex situ. Sin embargo, pocos investigadores han comparado la estructura genética de poblaciones restauradas y naturales de especies de plantas amenazadas. Metasequoia glyptostroboides Hu & Cheng (Taxodiaceae), un fósil viviente endémico de China, puede ser la especie amenazada recuperada más exitosamente, con mucho más individuos y una distribución mucho mayor que la indicada por registros fósiles. Utilizamos amplificaciones aleatorias de marcadores de ADN polimórfico para comparar la estructura genética de poblaciones artificiales con la de poblaciones silvestres y para determinar si la estructura genética de M. glyptostroboides se ha recuperado como lo ha hecho su distribución. La variación genética de ‡Address correspondence to X.-Y. Chen, email Li et al. Genetic Variation in Metasequoia 225poblaciones silvestres de M. glyptostroboides fue menor que la del ...

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CuO nanofibers (NFs) were fabricated via the traditional electrospinning technique and subsequent thermal treatment processes. Using CuO NFs as precursors and glucose as a reducing agent, CuO/Cu 2 O NFs, with high surface areas and ultralong one dimensional (1D) nanostructures, were obtained by a partial reduction of CuO NFs. Comparing with pure CuO NFs, CuO/Cu 2 O NFs, as non-enzymatic electrode materials, showed a much higher sensitivity of 830 mA mM À1 cm À2 and a much wider detection range from 0.5 mM to 10 mM for the amperometric detection of glucose. The excellent electrocatalytic performances could be ascribed to the following advantages: (1) the CuO/Cu 2 O NFs with Cu(II)/Cu(I) multiple oxidation states system could promote the redox reactions between electrode materials and glucose, and the reactive sites became more active due to the synergic effect; (2) the surface of CuO/ Cu 2 O NFs became smoother after partial reduction, resulting in less adsorption of the intermediates during the oxidation of glucose, generating the enlarged detection range. Therefore, the CuO/Cu 2 O composite NFs electrode materials, with a multiple oxidation states system, would be promising candidates for the development of non-enzymatic glucose sensors.

Carbon-modified BiVO(4) microtubes embedded with Ag nanoparticles (BVO@C/Ag MTs) were obtained by a two-step fabrication route. First, the BiVO(4)@carbon core-shell microtubes (BVO@C MTs) were fabricated by using BiVO(4) microtubes (BiVO(4) MTs) as a hard-template through a hydrothermal approach. Next, small Ag nanoparticles (Ag NPs) with well-dispersed distribution were assembled inside the carbon layer of the BVO@C MTs via an in situ reduction method. The results showed that small Ag NPs were well dispersed inside the carbon layer of approximately 8 nm in thickness around the BiVO(4) microtubes. The photocatalytic studies revealed that the BVO@C/Ag MTs exhibited the highest photocatalytic activity for photodegradation of rhodamine B (RB) compared to the pure BVO-MTs, BVO@C MTs under visible light irradiation. The high separation efficiency of photogenerated electron-hole pairs based on the photosynergistic effect among the three components of BiVO(4), carbon, and Ag and the improved visible light utilization from the sensitizing effects of carbon layers both contribute to the enhanced photocatalytic activity. The BVO@C/Ag MTs did not exhibit any significant loss of activity after three cycles of RB photodegradation, which results from the fact that the presence of the carbon layer could inhibit loss and oxidation of Ag NPs during repeated applications. The BVO@C/Ag MTs could be easily recovered by sedimentation due to their one-dimensional nanostructural property.

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