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Environmental health has recently become more and more important in the discussion of international health issues. Due to the impact of haze pollution on human health, ecological environment and climate change, it has become the first problem to be solved in the process of protecting environmental health. PM2.5 is the main cause of haze pollution. Based on the observation data of PM2.5 concentration in 368 cities in China from February to march in 2020, this paper uses the statistical model of spatial data to reveal the spatial and temporal pattern distribution of PM2.5 in China during the period of severe outbreak and spread (February 3 to March 29) of 8 weeks and 56 days. The analysis results show that 1) during the epidemic period, the average concentration of PM2.5 in China ranged from 32.876 to 42.173, which generally showed a trend of rapid decrease and then rebound and continued decline after the outbreak of the epidemic. 2) in terms of space, the concentration of PM2.5 is the highest in the central region, higher in the north than in the south, and higher in the eastern bohai rim region and northern China than in the western qinghai-tibet plateau and Himalayan mountain belt. The high-value areas were mainly distributed in the north China plain, the beijing-tianjin-hebei region, urumqi and hotan regions of xinjiang. 3) the hot spot analysis shows that the hot spots of pollution distribution are the beijing-tianjin-hebei region and the north China plain. The cold spots are the pearl river delta and the yunnan-guizhou region. 4) spatial autocorrelation analysis shows that the average weekly concentration of PM2.5 shows a strong local spatial autocorrelation.

Metasurfaces are nanopatterned structures of sub-wavelength thickness. Their effective refractive index and spectral characteristic can be tailored by material composition, intrinsic and extrinsic resonances, structure size, and ambient conditions. Consequently, they allow for phase, amplitude, polarisation, and spatial control of an optical field beyond what natural materials can offer. Dielectric metasurfaces with lower loss have opened a wide range of new applications such as enhanced imaging, structural colour, holography, and planar sensors. In particular, beam steering and control measures such as nonlinear optics, ultrafast optics, and quantum optics are of increasing importance for quantum communication, computation, and information processing. In this review, the recent progress on dielectric metasurfaces is summarised, including advanced fabrication technologies and novel applications from advanced wavefront shaping to quantum platforms. In addition, a perspective for the future development of the field is presented.

Background Knowledge of the factors that influence maternal serum screening (MSS) service utilization can be used to develop health policies to promote equitable access to MSS and further diagnostic tests. The purpose of this study was to find the factors associated with utilization of MSS as well as the current status of service utilization in mainland China. Methods This was a hospital-based cross-sectional study with respondents interviewed with a questionnaire designed based on Andersen’s behavioral model. Descriptive statistics, univariate analysis, and multilevel logistic regression analysis were used to identify the factors associated with MSS utilization, and to explore potential methods to improve screening uptake. Results A total of 8110 women who had given birth within the previous 7 days in one of 111 participating institutions from six provinces in mainland China were interviewed. Approximately 36 % of the participants had used MSS. Women between 20 and 35 years, who resided in urban areas, were educated, were in a stable occupation, who had health knowledge, who attended maternal preparation classes, who had received eight or more prenatal checkups, who were from a region of higher social economic status, and who delivered in a tertiary healthcare institution were significantly more likely to use MSS than their counterparts. As compared with other factors, insufficient education is the single most important demographic factor for service underutilization. Conclusions Efforts should not only be made to target the population that underuses MSS, but the overall organization of MSS service delivery should be assessed during policy development to make access to MSS equitable to the entire population of mainland China.

University laboratory is an important base for cultivating high quality innovative talents. The construction of experimental teaching demonstration center plays an important role in improving the level of experimental teaching and personnel training quality, enhancing undergraduates' practical ability and innovative spirit, and improving laboratory construction and management level. Experimental teaching is an important part of the construction of national experimental teaching demonstration center. The reform must aim at improving undergraduates' ability. How to construct scientific reasonable experimental curriculum teaching with independent operation mechanism, break the situation that the experiment (practice) curriculums are too much attached on theory curriculums, promote the harmonious development of the experimental teaching quality and scale, have become the core problem of the construction of experimental teaching demonstration center. The purpose of this independent teaching operation mechanism is to improve the undergraduates' innovation ability and engineering practice ability, so that undergraduates have enough competitiveness in employment in