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The hierarchical flower-like CuO nanostructure was synthesized by a facile sol-gel method without template. Indirectly-heated sensors are fabricated by coating the sol-gel on ceramic tubes with signal electrodes and subsequent annealing. The obtained nanostructures are analyzed by X-ray diffraction and scanning electron microscopy. Their gas sensing performances were investigated. The results indicated that the sensor based on hierarchical flower-like CuO exhibited excellent sensing properties towards ethanol, formaldehyde, acetone and dimethylbenzene. The sensor based on the CuO exhibited the optimal gas sensing performance, giving a ppb-level detection limit and a high response (R/R) of 1.378 to 50 ppb formaldehyde at 250 °C. The response and recovery time of the flower-like CuO nanostructure sensor are 11.9 and 8.4 s, respectively. The significantly enhanced sensing properties to formaldehyde could be attributed to the changes in crystallite size and specific surface area. The results indicate that the hierarchical flower-like CuO nanostructure gas sensor can be a simple and useful platform for formaldehyde and other volatile organic compounds sensing application. [ABSTRACT FROM AUTHOR]

To analyse inner- and inter-annual changes, disaster events of 55 countries in Africa from 1990 to 2014 recorded in the International Disaster Database (EM-DAT) were recounted by year and month and were reorganised in five different regions. Thematic maps of flood disasters in Africa between 1990 and 2014 were drawn using ArcGIS 9.3 to research the spatial distribution patterns of average annual flood frequency, total deaths, total affected, and damage. There were eight natural and socio-economic indicators chosen to explore the main factors influencing the spatio-temporal distribution of flood disasters in Africa, including precipitation, ENSO, runoff, forest coverage rate, reservoir capacity, per capita GDP, population, and urbanisation rate. Studies show that seasonal changes of flood disasters in various regions of Africa, except North Africa, are closely related to precipitation. Annual flood frequencies, from 1990 to 2014, showed a fluctuating upward trend and were in good agreement with ENSO years. In terms of spatial distributions, Ethiopia, Kenya, Somalia, Tanzania in eastern Africa, Nigeria in western Africa, and Libya, and Sudan in northern Arica are flood-prone countries, and main factors influencing spatial disparities include runoff, per capita GDP, population, and urbanisation rate. [ABSTRACT FROM AUTHOR]

3D rose-like NiO nanoparticles have been prepared by electrodeposition method. The samples were characterized through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The phase and morphology observations showed the formation of rose-like hierarchical structures with an average particle diameter of 400-500 nm. Gas sensing properties of the as-synthesized rose-like NiO nanoparticles were evaluated by the detection of volatile and toxic gases including ethanol, methanol, and acetone. It was found that NiO nanoroses exhibited a highly response to the three gases at 230 °C. Furthermore, at 5 ppm, the NiO nanorose-based sensor gave a higher response to ethanol ( R/ R = 9.11) and methanol ( R/ R = 8.36), in comparison with acetone ( R/ R = 6.44). The results indicated the NiO nanorose-based sensors displayed a rapid response and recovery as well as good reproducibility. [ABSTRACT FROM AUTHOR]

Cadmium (Cd)-contaminated rice is one of the most important sources of cadmium exposure in the general population from some Asian countries. This study was conducted to assess cadmium exposure from uncooked rice in rural mining areas based on the bioaccessible fraction of cadmium using an in vitro digestion model. The biotoxic effects of cadmium in uncooked rice from mining areas were much higher than those in the control area, based not only on their higher total concentration (52.49 vs. 7.93 μg kg), but also on their higher bioaccessibility (16.94% vs. 2.38%). In the mining areas, the bioaccessible fraction of cadmium in uncooked rice has a significant positive correlation with the total concentration of cadmium in rice and there was quarterly unsafe rice to the public in the mining areas. The results indicated that the in vitro digestion model could be a useful and economical tool for providing the solubilization or bioaccessibility of uncooked rice in the mining area. The results could be helpful in conducting future experiments of cooked rice in the vitro model. [ABSTRACT FROM AUTHOR]

This study focuses on the development stages of ageing and its regional differences in China based on examination of official statistics and documents. The development of ageing in China has experienced three major stages. Firstly, in the 1950s, low coefficient of elderly population (over 65 years) paced up to primary adult type. Secondly, there was a deeply drop of the elderly population because of natural disaster and political factors in the 1960s. Thirdly, from the 1970s to the end of 20th century, the constant increasing of elderly coefficient made China close to elderly society. With statistic data of population, Logistic model is used to simulate the future development of ageing, and two characteristics of development of ageing are presented. Firstly, as for ageing from 2005 to 2050, the elderly coefficient will grow up significantly from 8.48% to 16.30%. Secondly, after 2025, the increasing rate of elderly coefficient will slow down gradually. The regional differences of elderly population in China can be summarized as follows: 1) the eastern China possesses higher elderly coefficient and huger elder population than the western China; 2) about 47.4% of municipalities and provinces in the eastern China become elderly especially Shanghai, Zhejiang Province, Jiangsu Province, Beijing, Tianjin and Shandong Province; 3) ageing intensity is higher in rural area than urban area but getting close each other, and there are more elderly people in rural area than in urban area. Therefore, these will arose aged care problems, and it becomes important issue to establish the social security system in rural areas as soon as possible for elderly people. [ABSTRACT FROM AUTHOR]