Fabrication of highly efficient heterostructured Ag-CeO2/g-C3N4 hybrid photocatalyst with enhanced visible-light photocatalytic activity

On the basis of hydrothermal synthesis of Ag-CeO2 microspheres,Ag-CeO2/g-C3N4 composite photocatalyst with heterostructure was prepared by simple solvent evaporation of Ag-CeO2 and g-C3N4.To characterize the composition,structure,morphology and light absorption properties of the as-prepared Ag-CeO2/g-C3N4 composites,XRD,FTIR XPS,SEM,TEM,PL,BET and UV-vis DRS were used,respectively.The as-prepared photocatalyst was subjected to photocatalytic degradation of pollutants,and the prepared composite material has excellent photocatalytic activity for photodegradation of methylene blue(MB).The research shows that the photocatalytic properties of Ag-CeO2/g-C3N4 composites were related to the mass ratio of Ag-CeO2 microspheres and g-C3N4 nanosheets.When the ratio of Ag-CeO2 microspheres:g-C3N4 is 1:5,the composites have the highest photocatalytic activity,which was 9.6 and 3.3 times that of single Ag-CeO2 and g-C3N4,respectively.The improvement of photocatalytic activity is attributed to the heterostructure between the composite materials and the addition of noble metal silver,and the degradation of methylene blue by the visible light irradiation material is greatly improved.Finally,an attempt was made to analyze the principle of photocatalytic degradation of pollutants in prepared materials.

Relationships of Residential Distance to Major Traffic Roads with Dementia Incidence and Brain Structure Measures:Mediation Role of Air Pollution

Background:Uncertainty exists regarding the operating pathways between near-roadway exposure and dementia incidence.We intend to examine relationships between proximity to major roadways with dementia incidence and brain MRI structure measures,and potential mediation roles of air and noise pollution.Methods:The cohort study was based on the UK Biobank.Baseline survey was conducted from 2006 to 2010,with linkage to electronic health records conducted for follow-up.Residential distance to major roadways was ascertained residential address postcode.A land use regression model was applied for estimating traffic-related air pollution at residence.Dementia incidence was ascertained using national administrative databases.Brain MRI measures were derived as imagederived phenotypes,including total brain,white matter,gray matter,and peripheral cortical gray matter.Results:We included 460,901 participants[mean(SD)age:57.1(8.1)years;men:45.7%].Compared with individuals living>1,000 m from major traffic roads,living≤1,000 m was associated with a 13%to 14%higher dementia risk,accounting for 10%of dementia cases.Observed association between residential distance and dementia was substantially mediated by traffic-related air pollution,mainly nitrogen dioxide(proportion mediated:63.6%;95%CI,27.0 to 89.2%)and PM2.5(60.9%,26.8 to 87.0%).The shorter residential distance was associated with smaller volumes of brain structures,which was also mediated by traffic-related air pollutants.No significant mediation role was observed of noise pollution.Conclusions:The shorter residential distance to major roads was associated with elevated dementia incidence and smaller brain structure volumes,which was mainly mediated by traffic-related air pollution.