Hydrogen producing water treatment through mesoporous TiO2 nanofibers with oriented nanocrystals

The development of well-defined TiO2 nanoarchitectures is a versatile strategy to achieve high-efficiency photocatalytic performance.In this study,mesoporous TiO2 nanofibers consisting of oriented nanocrystals were fabricated by a facile vapothermal-assisted topochemical transformation of preformed H-titanate nanobelts.The vapothermal temperature is crucial in tuning the microstructures and photocatalytic redox properties of the resulting mesoporous TiO2 nanofibers.The microstructures were characterized with XRD,TEM,XPS and nitrogen adsorption-desorption isotherms,etc.The photocatalytic activities were evaluated by photocatalytic oxidation of organic pollutant(Rhodamine B as an example)as well as photocatalytic reduction of water to generate hydrogen(H2).The nanofibers vapothermally treated at 150°C showed the highest photocatalytic activity in both oxidation and reduction reactions,2 times higher than that of P25.The oriented alignment and suitable mesoporosity in the resulting nanofiber architecture were crucial for enhancing photocatalytic performances.The oriented alignment of anisotropic anatase nanocrystals shall facilitate faster vectorial charge transportation along the nanofibers architecture.And,the suitable mesoporosity and high surface area would also effectively enhance the mass exchange during photocatalytic reactions.We also demonstrate that efficient energy-recovering photocatalytic water treatments could be accomplished by a cascading oxic-anoxic process where the dye is degraded in the oxic phase and hydrogen is generated in the successive anoxic phase.This study showcases a novel and facile method to fabricate mesoporous TiO2 nanofibers with high photocatalytic activity for both clean energy production and environmental purification.

Ribosome Profiling Reveals Genome-wide Cellular Translational Regulation upon Heat Stress in Escherichia coli

Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome in Escherich＆ coli, we conducted ribosome profiling in parallel with RNA-Seq to investigate the alterations in transcription and translation efficiency when E. coli cells were exposed to a mild heat stress （from 30 ~C to 45 ~C）. While general changes in ribosome foot- prints correlate with the changes of mRNA transcripts upon heat stress, a number of genes show differential changes at the transcription and translation levels. Translation efficiency of a few genes that are related to environment stimulus response is up-regulated, and in contrast, some genes func- tioning in mRNA translation and amino acid biosynthesis are down-regulated at the translation level in response to heat stress. Moreover, our ribosome occupancy data suggest that in generalribosomes accumulate remarkably in the starting regions of ORFs upon heat stress. This study pro- vides additional insights into bacterial gene expression in response to heat stress, and suggests the presence of stress-induced but yet-to-be characterized cellular regulatory mechanisms of gene expression at translation level.