Photocatalytic Optical Hollow Fiber with Enhanced Visible-light-driven CO2 Reduction.

A visible-light-driven CO2 reduction optical fiber is fabricated using graphene-like nitrogen-doped composites and hollow quartz optical fibers to achieve enhanced activity, selectivity, and light utilization for CO2 photoreduction. The composites are synthesized from a lead-based metal-organic framework (TMOF-10-NH2 ) and g-C3 N4 nanosheet (CNNS) via electrostatic self-assembly. The TMOF-10-NH2 /g-C3 N4 (TMOF/CNNS) photocatalyst with an S-type heterojunction is coated on optical fiber. The TMOF/CNNS coating, which has a bandgap energy of 2.15 eV, has good photoinduced capability at the coating interfaces, high photogenerated electron-hole pair yield, and high charge transfer rate. The conduction band potential of the TMOF/CNNS coating is more negative than that for CO2 reduction. Moreover, TMOF facilitates the CO desorption on its surface, thereby improving the selectivity for CO production. High CO2 photoreduction and selectivity for CO production is demonstrated by the TMOF/CNNS-coated optical fiber with the cladding/core diameter of 2000/1000 µm, 10 wt% TMOF in CNNS, coating thickness of 25 µm, initial CO2 concentration of 90 vol%, and relative humidity of 88% RH under the excitation wavelength of 380-780 nm. Overall, the photocatalytic hollow optical fiber developed herein provides an effective and efficient approach for the enhancement of light utilization efficiency of photocatalysts and selective CO2 reduction.

Photocatalytic synergistic biofilms enhance tetracycline degradation and conversion.

Tetracyclines are refractory pollutants that cause persistent harm to the environment and human health. Therefore, it is urgently necessary to develop methods to promote the efficient degradation and conversion of tetracyclines in wastewater. This report proposes a photobiocatalytic synergistic system involving the coupling of GeO2/Zn-doped phosphotungstic acid hydrate/TiO2 (GeO2/Zn-HPW/TiO2)-loaded photocatalytic optical hollow fibers (POHFs) and an algal-bacterial biofilm. The GeO2/Zn-HPW/TiO2 photocatalyst exhibits a broad absorption edge extending to 1000 nm, as well as high-efficiency photoelectric conversion and electron transfer, which allow the GeO2/Zn-HPW/TiO2-coated POHFs to provide high light intensity to promote biofilm growth. The resulting high photocatalytic activity rapidly and stably reduces the toxicity and increases the biodegradability of tetracycline-containing wastewater. The biofilm enriched with Salinarimonas, Coelastrella sp., and Rhizobium, maintains its activity for the rapid photocatalytic degradation and biotransformation of intermediates to generate the O2 required for photocatalysis. Overall, the synergistic photocatalytic biofilm system developed herein provides an effective and efficient approach for the rapid degradation and conversion of water containing high concentrations of tetracycline.

Dry eye syndrome in elderly Tibetans at high altitude: a population-based study in China.

PURPOSE: To determine the prevalence of dry eye syndrome, analyze the relationship between dry eye symptoms and signs, and identify associated risk factors for dry eye syndrome in an elderly Tibetan population at high altitude. METHODS: A population-based survey was conducted from October 2006 to December 2006. A stratified, clustered, random sampling procedure was used to select 2632 native Tibetan people >or=40 years of age. Symptoms of dry eye were assessed by using a 6-item validated questionnaire. Dry eye syndrome was diagnosed in those subjects having 1 or more symptoms often or all the time. Positive signs included a tear film breakup time of or=1. Correlations between symptoms and signs were analyzed. RESULTS: Of a total of 2632 eligible subjects, 2229 (84.69%) were examined. The data of 1840 participants were analyzed. Of 1840 participants, 52.4% (95% confidence interval: 50.2-54.7) were symptomatic. The tear film breakup time of or=1 was seen in 5.8% (95% confidence interval: 4.7-6.9). The correlations between dry eye symptoms and signs were statistically significant. Independent risk factors for dry eye syndrome were positive dry eye signs, increased age, low education level and socioeconomic status, and higher altitude. CONCLUSIONS: This study shows a high prevalence rate of dry eye syndrome in elderly Tibetans, representing an important health problem.