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BackgroundMany studies have considered the prevalence of dementia in mainland China, Hong Kong and Taiwan. However, area level estimates have not been produced. This study examines area differences across mainland China, Hong Kong and Taiwan adjusting for the effect of methodological factors with the aim of producing estimates of the numbers of people with dementia in these areas.Method and FindingsA search of Chinese and English databases identified 76 dementia prevalence studies based on samples drawn from mainland China, Hong Kong and Taiwan between 1980 and 2012. A pattern of significantly decreasing prevalence was observed from northern, central, southern areas of mainland China, Hong Kong and Taiwan. Area variations in dementia prevalence were not explained by differences in methodological factors (diagnostic criteria, age range, study sample size and sampling method), socioeconomic level or life expectancy between areas. The results of meta-analysis were applied to current population data to provide best estimate. Based on the DSM-IV diagnostic criteria, the total number of people aged 60 and over with dementia in mainland China, Hong Kong and Taiwan is 8.4 million (4.6%, 95% CI: 3.4, 5.8) and in northern, central and southern areas are 3.8 (5.1%, 95% CI: 4.1, 6.1), 3.2 (4.4%, 95% CI: 3.2, 5.6) and 1.2 (3.9%, 95% CI: 2.3, 5.4) million respectively. These estimates were mainly based on the studies existing in highly developed areas and potentially affected by incomplete and insufficient data.ConclusionsThe findings of this review provide a robust estimate of area differences in dementia prevalence. Application of the estimated prevalence to population data reveals the number of people with dementia is expected to double every 20 years, areas in mainland China will be facing the greatest dementia challenge.

Light-induced halide segregation limits the bandgap tunability of mixed-halide perovskites for tandem photovoltaics. Here we report that light-induced halide segregation is strain-activated in MAPb(I1−xBrx)3 with Br concentration below approximately 50%, while it is intrinsic for Br concentration over approximately 50%. Free-standing single crystals of CH3NH3Pb(I0.65Br0.35)3 (35%Br) do not show halide segregation until uniaxial pressure is applied. Besides, 35%Br single crystals grown on lattice-mismatched substrates (e.g. single-crystal CaF2) show inhomogeneous segregation due to heterogenous strain distribution. Through scanning probe microscopy, the above findings are successfully translated to polycrystalline thin films. For 35%Br thin films, halide segregation selectively occurs at grain boundaries due to localized strain at the boundaries; yet for 65%Br films, halide segregation occurs in the whole layer. We close by demonstrating that only the strain-activated halide segregation (35%Br/45%Br thin films) could be suppressed if the strain is properly released via additives (e.g. KI) or ideal substrates (e.g. SiO2).

The production of cellulose-based aerogels from the conversion of cheap and rich precursors using environmentally friendly techniques is a very attractive subject in materials chemistry. In this work, we reports a facile strategy to construct flame retardant, sound-adsorption and mechanical enhancement cellulose-based composite aerogels by the incorporation of aluminum hydroxide nanoparticles (AH NPs) into cellulose gels via an in-situ sol-gel process, followed by freeze-drying to coat AH NPs on cellulose composite aerogels (AH NPs@cellulose composite aerogels). The results demonstrated that the AH NPs homogeneous dispersion within cellulose aerogel, and the presence of AH NPs did not have a remarkable influence on the homogeneous porous structure of cellulose aerogels when compared with cellulose aerogel prepared from the NaOH/urea/thiourea solution. The prepared composite cellulose aerogels showed excellent flame retardancy, the peak of heat release rate (PHRR) of the composite aerogels decreased significantly from 280 W/g of the control sample to 22 W/g, and total heat release (THR) of the composite aerogels decreased remarkably from 13.2 kJ/g to 1.6 kJ/g. Moreover, the incorporation of AH NPs composite aerogels exhibited remarkable mechanical properties, the compressive strength of the composite aerogels increased significantly from 0.08 MPa to 1.5 MPa. In addition, AH NPs composite cellulose aerogels have excellent sound absorption at high frequencies with a maximum sound absorption coefficient of 1. AH NPs composite cellulose aerogels have strong water and oil affinity. After immersing the samples in mixed silica nanoparticles, heptadecafluorononanoic, and fluoroalkyl silane solutions they became super-antiwetting, with a water contact angle (CA) larger than 150° and oil CA larger than 140°. In summary, this study provides a facile strategy to rationally construct flame retardant, mechanically robust, high-efficiency sound-adsorption and superamphiphobic cellulose-based composite aerogels, which have promising applications in the future as green engineering materials.

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