NH3-SCR performance and the resistance to SO2 for Nb doped vanadium based catalyst at low temperatures

Niobium oxide as the promoter was doped in the V/WTi catalyst for the selective catalytic reduction（SCR）of NO.The results showed that the addition of Nb2O5could improve the SCR activity at low temperatures and the 6 wt.%additive was an appropriate dosage.The enhanced reaction activity of adsorbed ammonia species and the improved dispersion of vanadium oxide might be the reasons for the elevation of SCR activity at low temperatures.The resistances to SO2of 3V6Nb/WTi catalyst at different temperatures were investigated.FTIR spectrum and TG-FTIR result indicated that the deposition of ammonium sulfate species was the main deactivation reason at low temperatures,which still exhibited the reactivity with NO above 200℃ on the catalyst surface.There was a synergistic effect among NH3,H2O and SO2that NH3and H2O both accelerated the catalyst deactivation in the presence of SO2at 175℃.The thermal treatment at 400℃ could regenerate the deactivated catalyst and get SCR activity recovered.The particle and monolith catalysts both kept stable NOxconversion at 225℃ with high concentration of H2O and SO2during the long time tests.

Synthesis of Single-Crystalline Anatase TiO_2 Nanorods With High-Performance Dye-Sensitized Solar Cells

Single-crystalline anatase TiO2nanorods have been prepared by solvothermal method using tetrabutylammonium hydroxide（TBAH） as a morphology controlling agent.The obtained TiO2nanorods are dominated by a large percentage of {010} facets.The power conversion efficiency of dye-sensitized solar cell（DSSC） based on anatase TiO2nanorods（8.66%） exhibits a significant improvement（35%） compared to that of P25 TiO2（5.66%）.The high performance of the anatase TiO2nanorods solar cell is ascribed to their large percent of exposed {010} facets as well as balancing their surface areas and sizes.

Molecular basis for the inhibition of β-hydroxyacyI-ACP dehydratase HadAB complex from Mycobacterium tuberculosis by flavonoid inhibitors

Dehydration is one of the key steps in the biosynthesis of mycolic acids and is vital to the growth of Mycobac- terium tuberculosis （Mtb）. Consequently, stalling dehy-dration cures tuberculosis （TB）. Clinically used anti-TB drugs like thiacetazone （TAC） and isoxyl （ISO） as well as flavonoids inhibit the enzyme activity of the β-hydroxy- acyI-ACP dehydratase HadAB complex. How this inhi- bition is exerted, has remained an enigma for years. Here, we describe the first crystal structures of the MtbHadAB complex bound with flavonoid inhibitor butein, 2＇,4,4＇-trihydroxychalcone or fisetin. Despite sharing no sequence identity from Blast, HadA and HadB adopt a very similar hotdog fold. HadA forms a tight dimer with HadB in which the proteins are sitting side-by-side, but are oriented anti-parallel. While HadB contributes the catalytically critical His-Asp dyad, HadA binds the fatty acid substrate in a long channel. The atypical double hotdog fold with a single active site formed by MtbHadAB gives rise to a long, narrow cavity that vertically traverses the fatty acid binding channel. At the base of this cavity lies Cys61, which upon muta- tion to Ser confers drug-resistance in TB patients. We show that inhibitors bind in this cavity and protrude into the substrate binding channel. Thus, inhibitors of MtbHadAB exert their effect by occluding substrate from the active site, The unveiling of this mechanism of inhibition paves the way for accelerating development of next generation of anti-TB drugs,