Synthesis of Ag_(2)S nano-sized clusters and their chemical sensitizations in AgCl cubic and {100} tabular microcrystal imaging systems

In recent years much attention has been devoted to AgCl emulsion owing to its se-rial advantages and inimitable potential.But in the research of this emulsion a thorny problem remains unsolved till now,which is the improvement in sensitivity is always accompanied with high fog density.In this work 5 nm Ag_(2)S particles were prepared and used as novel sensitizers in AgCl cubic and{100}tabular microcrystal emulsions.The novel sensitizer shows an effective sensitizing ability for silver chloride emulsion,and it is superior to the traditional Na_(2)S_(2)O_(3) sensi-tizer because by using it comparatively high sensitivity can be obtained with lower fog density.So the above sensitizing problem is going to be effectively solved.To discover the evolution mechanism of the sensitizer clusters and explain their excellent sensitizing properties,diffuse reflectance spectroscopy(DRS)was used as a probe on the AgCl microcrystal surface.

Advances in Noble Metal-Decorated Metal Oxide Nanomaterials for Chemiresistive Gas Sensors:Overview

Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analysis.Among various chemiresistive sensing materials,noble metal-decorated semiconducting metal oxides(SMOs)have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals.This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures(e.g.,nanoparticles,nanowires,nanorods,nanosheets,nanoflowers,and microspheres)for high-performance gas sensors with higher response,faster response/recovery speed,lower operating temperature,and ultra-low detection limits.The key topics include Pt,Pd,Au,other noble metals(e.g.,Ag,Ru,and Rh.),and bimetals-decorated SMOs containing ZnO,SnO_(2),WO_(3),other SMOs(e.g.,In_(2)O_(3),Fe_(2)O_(3),and CuO),and heterostructured SMOs.In addition to conventional devices,the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed.Moreover,the relevant mechanisms for the sensing performance improvement caused by noble metal decoration,including the electronic sensitization effect and the chemical sensitization effect,have also been summarized in detail.Finally,major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.

Sick Neighborhood Syndrome: Population with Multiple Chemical Sensitivity Adjacent to Bioethanol Distillery

The population of a neighborhood in the city of Córdoba presents general irritant symptoms since a bioethanol distillery began to operate there, from which formaldehyde, toluene, xylene mainly emanate. At the request of the community, collective environmental health was evaluated with a cross-sectional study of prevalence of these conditions. 53% of the residents reported respiratory disorders, conjunctivitis 31%, headaches 27%, dermatitis 23% and dyspepsia 22%. 57% of children aged 6 - 7 use bronchodilators (an indicator of asthma). 66% of the population has one of these conditions, 46% has two and 26% has three;children are the most affected. The results coincide with the Consensus on Multiple Chemical Sensitivity Syndrome in that it is reproducible by repeated chemical exposure, is chronic and does not improve without eliminating exposure, affecting multiple organs and systems. 14.8% of newborns feature malformations, while in the rest of the city, only 1.7% did. Similar to the Sick Building Syndrome, the collective health picture found suggests a “Sick Neighborhood Syndrome”.

Improved sensing performance of WO_(3) nanoparticles decorated with Ag and Pt nanoparticles

Gas sensors built with metal oxide semiconductors have attracted tremendous attention due to the growing demand for the detection of inflammable,explosive and toxic gases.Herein,to improve the sensing response,WO_(3) nanoparticles decorated with Ag and Pt bimetals(Ag and Pt/WO_(3) NPs)have been developed via combined hydrolysis and hydrothermal strategies.Such sensors prototypes show high response to acetone(Ra/Rg=250@100×10^(-6),140℃),which is 6.1 fold as high as that of the pristine WO_(3) NPs(Ra/Rg=41@100×10^(-6),140℃).Moreover,the recovery time of Ag and Pt/WO_(3) NPs was reduced from 138 to 13 s compared with that of the pristine WO_(3) NPs.The improved acetone sensing performance may be attributed to that the chemical and electronic sensitization of Ag and Pt to WO_(3) NPs increases adsorbed oxygen species,speeds up the reaction and thus boosts the sensing response.Our strategy that decoration of dual precious metals onto WO_(3) NPs improves the acetone sensing performance may be applied to the gas sensors of other sensing materials.