Synthesis and characterization of Pt-MoO_x-TiO_2 electrodes for direct ethanol fuel cells

To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells,carbon nanotubes were modified by titanium dioxide （donated as CNTs@TiO2） and subsequently served as the support for the preparation of Pt/CNTs@TiO2 and Pt-Mo/CNTs@TiO2 electrocatalysts via a UV-photoreduction method.The physicochemical characterizations of the catalysts were carried out by using X-ray diffraction （XRD）,transmission electron microscopy （TEM）,X-ray photoelectron spectroscopy （XPS）,and infrared spectroscopy of adsorbed probe ammonia molecules.The electrocatalytic properties of the catalysts for methanol oxidation were investigated by the cyclic voltammetry technique.The results show that Pt-Mo/CNTs@TiO2 electrode exhibits the highest performance in all the electrodes.It is explained that,the structure,the oxidation states,and the acid-base properties of the catalysts are influenced due to the strong interaction between Ti and Mo species by adding TiO2 and MoOx to the Pt-based catalysts.

Orthogonal Solubility in Fully Conjugated Donor-Acceptor Block Copolymers： Compatibilizers for Polymer/Fullerene Bulk-Heterojunction Solar Cells

Donor-acceptor （D-A） type fully conjugated block copolymer systems have been rarely reported due to the challenges in synthetic approaches to prepare well-defined low-polydispersity products. In this work, fully conjugated block copolymers are synthesized in a one-pot reaction through Stille coupling polycondensation, by utilizing the end-functional polymer copolymerization method. End-functional P3HT are copolymerized with AA （2,7-dihromo-9-（heptadecan-9-yl）-9H- carbazole） and BB （4,7-bis（5-（trimethylstannyl）thiophen-2-yl）benzo[c][1,2,5]thiadiazole, TBT） type monomers, respectively. The orthogonal solubility between the very soluble P3HT donor and the insoluble PCDTBT acceptor block improves the purity of block copolymers as well as distinct nano-scale phase-separation compared with other reports on miscibility of donor and acceptor polymer block. Further purification via preparative GPC is carried out to remove the excess of unreacted P3HT and free PCDTBT as well as to achieve low polydispersity of block copolymers. The chemical structure of the P3HT- b-PCDTBT block copolymers are verified via IH-NMR, and further confirmed by FTIR spectra. The block copolymer shows broad absorption and moderate optical band gap of 1.8 eV. Furthermore, the fully conjugated block copolymer films exhibit significant fine structures, much smoother film morphology compared to P3HT/PCDTBT polymer blends. By adding a small amount of block copolymer P3HT-b-PCDTBT as a compatibilizer into the bulk-heterojunction of P3HT：PC61BM blends, polymer solar ceils with an 8% increase of short circuit current （Jse） and 10% increase of power conversion efficiency （PCE） are achieved owing to the improvement of the active-layer film morphology. To the best of our knowledge, this is the first report on donor-acceptor type fully conjugated block copolymer as an effective ternary additive in polymer： fullerene bulk heterojunction solar cells.

Risk assessment and genomic characterization of Zika virus in China and its surrounding areas

Background:Zika virus (ZIKV) has emerged as a global pathogen causing significant public health concerns.China has reported several imported cases where ZIKV were carried by travelers who frequently travel between China and ZIKV-endemic regions.To fully characterize the ZIKV strains isolated from the cases reported in China and assess the risk of ZIKV transmission in China,comprehensive phylogenetic and genetic analyses were performed both on all ZIKV sequences of China and on a group of scientifically selected ZIKV sequences reported in some of the top interested destinations for Chinese travelers.Methods:ZIKV genomic sequences were retrieved from the National Center for Biotechnology Information database through stratified sampling.Recombination event detection,maximum likelihood (ML) phylogenetic analysis,molecular clock analysis,selection pressure analysis,and amino acid substitution analysis were used to reconstruct the epidemiology and molecular transmission of ZIKV.Results:The present study investigated 18 ZIKV sequences from China and 70 sequences from 16 selected countries.Recombination events rarely happens in all ZIKV Asian lineage.ZIKV genomes were generally undergone episodic positive selection (17 sites),and only one site was under pervasive positive selection.All ZIKV imported into China were Asian lineage and were assigned into two clusters:Venezuela-origin (cluster A) and Samoa-origin cluster (cluster B) with common ancestor from French Polynesia.The time of most recent common ancestors of Cluster A dated to approximately 2013/11 (95% highest posterior density [HPD] 2013/06,2014/ 03) and cluster B dated to 2014/08 (95% HPD 2014/02,2015/01).Cluster B is more variable than Cluster A in comparison with other clusters,but no varied site of biological significance was revealed.ZIKV strains in Southeast Asia countries are independent from strains in America epidemics.Conclusions:The genetic evolution of ZIKV is conservative.There are two independent introductions of ZIKV into China and China is in danger of autochthonous transmission of ZIKV because of high-risk surrounding areas.Southeast Asia areas have high risk of originating the next large-scale epidemic ZIKV strains.