In this work, Ag/TiO 2 nanoheterostructures with Ag nanocrystals well-grown on TiO 2 -based nanofiber mats have been achieved by means of a novel and straighforward protocol combining an electrospinning technique and a solvothermal process. The experimental results indicated that the morphology and size of the secondary Ag nanostructures could be tailored by altering the experimental parameters, such as the reaction time and solvent as well as the reducing agent in the solvothermal treatment. The investigation of photocatalytic ability showed that the Ag/TiO 2 nanoheterostructures possess an excellent photocatalytic activity superior to the pure TiO 2 nanofiber for the degradation of Rhodamine B (RB) dye driven by visible light. The results indicated that Ag might be responsible for the visible light induced photocatalytic degradation by improving the photogenerated electrons and holes separation as well as charge migration, allowing both the electrons and holes to partake in the overall photocatalytic reaction. In addition, Ag has a good light absorption capability, extending the response of TiO 2 to visible light. Finally, the corresponding possible mechanism related to the photocatalytic performance of the Ag/TiO 2 nanoheterostructures was discussed in detail. Additionally, the separation and recovery process of the Ag/TiO 2 nanoheterostructures might be easily acheived by sedimentation without a decrease in the photocatalytic ability because of their particular one-dimensional nanostructured nature.
As influenza viruses have developed resistance towards current drugs, new inhibitors that prevent viral replication through different inhibitory mechanisms are useful. In this study, we developed a screening procedure to search for new antiinfluenza inhibitors from 1,200,000 compounds and identified previously reported as well as new antiinfluenza compounds. Several antiinfluenza compounds were inhibitory to the influenza RNA-dependent RNA polymerase (RdRP), including nucleozin and its analogs. The most potent nucleozin analog, 3061 (FA-2), inhibited the replication of the influenza A/WSN/33 (H1N1) virus in MDCK cells at submicromolar concentrations and protected the lethal H1N1 infection of mice. Influenza variants resistant to 3061 (FA-2) were isolated and shown to have the mutation on nucleoprotein (NP) that is distinct from the recently reported resistant mutation of Y289H [Kao R, et al. (2010) Nat Biotechnol 28:600]. Recombinant influenza carrying the Y52H NP is also resistant to 3061 (FA-2), and NP aggregation induced by 3061 (FA-2) was identified as the most likely cause for inhibition. In addition, we identified another antiinfluenza RdRP inhibitor 367 which targets PB1 protein but not NP. A mutant resistant to 367 has H456P mutation at the PB1 protein and both the recombinant influenza and the RdRP expressing the PB1 H456P mutation have elevated resistance to 367. Our high-throughput screening (HTS) campaign thus resulted in the identification of antiinfluenza compounds targeting RdRP activity.high-throughput screening | antiinfluenza | influenza NP | influenza PB1 | chemical genetics
Using d-xylose as an appropriate chiral precursor, we have synthesized active neuraminidase inhibitor oseltamivir, antiflu drug Tamiflu, and novel phosphonate congeners that exhibit even stronger antiflu activities by inhibiting the neuraminidases of the wild-type and H274Y mutant of H1N1 and H5N1 viruses. Molecular modeling of the neuraminidase−phosphonate complex indicates a pertinent binding mode of the phosphonate with three arginine residues in the active site. Discovery of such potent neuraminidase inhibitors will offer an opportunity to the development of new anti-influenza drugs.
A library of 27 sialosides, including seventeen 2,3-linked and ten 2,6-linked glycans, has been prepared to construct a glycan array and used to profile the binding specificity of different influenza hemagglutinins (HA) subtypes, especially from the 2009 swine-originated H1N1 and seasonal influenza viruses. It was found that the HAs from the 2009 H1N1 and the seasonal Brisbane strain share similar binding profiles yet different binding affinities toward various α2,6 sialosides. Analysis of the binding profiles of different HA subtypes indicate that a minimum set of 5 oligosaccharides can be used to differentiate influenza H1, H3, H5, H7, and H9 subtypes. In addition, the glycan array was used to profile the binding pattern of different influenza viruses. It was found that most binding patterns of viruses and HA proteins are similar and that glycosylation at Asn27 is essential for receptor binding.
The periodical nonlinearity of an interferometer usually ranges from sub-nanometre scale to several nanometres. This nonlinearity limits the usefulness of an interferometer to the sub-nanometre level of accuracy in length measurements. A theoretical analysis of length measurement nonlinearities both in heterodyne and in one-frequency interferometers is reported in this paper. The nonlinearity of a heterodyne interferometer arises mainly from the cross talk between different frequencies of two linearly polarized beams. Both one-cycle and two-cycles nonlinearities were observed as the difference in optical path length changed from 0 to 2π. Unlike the heterodyne interferometer, the nonlinearity of the one-frequency interferometer arises mainly from the cross talk between two linearly orthogonal beams of the same frequency and only two cycles of periodical nonlinearity were observed as the difference in optical path length changed from 0 to 2π.
TiO2 nanoparticles were successfully fabricated on electrospun polyacrylonitrile (PAN) nanofibers via the coupling of electrospinning and hydrothermal pathway. A straightforward photocatalysis oxidation process has been developed for simultaneous desulfurization and denitrification of flue gas using the TiO2-PAN photocatalyst. Also, the influences of some important operating parameters, such as titanium loading content of catalyst, flue gas humidity, flue gas flow, and inlet flue gas temperature on removal efficiencies of SO2 and NO were investigated. The results demonstrated that removal efficiencies of 99.3% for SO2 and 71.2% for NO were attained under the following optimal experiment conditions: titanium loading content, 6.78 At %; gas flow rate, 200 mL/min; flue gas humidity, 5%; inlet flue gas temperature, 40 °C. Furthermore, the presumed reaction mechanism of SO2 and NO removal using TiO2-PAN photocatalyst under UV light was proposed.
The nonlinearity of one-frequency optical interferometry with quadrature fringe detection is the result of a number of factors including polarization mixing, unequal gain of detectors, imbalanced beams and lack of quadrature. An elliptical least-squares fitting technique to correct the nonlinearity is presented in this paper. Experimental results demonstrate that a nonlinearity-free condition can be achieved and the stability of the interferometer set-up in our laboratory is better than nm over 2.5 h.
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