16 research outputs found

    The convergence of PM2.5 concentration in Chinese cities: a distribution dynamic approach

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    To fill the gap in the research on the convergence trend of air pollutants since 2013 in China and overcome the Galton fallacy caused by the parametric regression method, this study examines the convergence trend of the annual average concentration of fine particulate matter 2.5 (PM2.5) in China’s prefecture-level cities after 2013 using a distribution dynamic approach. The winter PM2.5 pollution in Chinese cities is severe. Hence, the convergence of the average winter PM2.5 concentration of prefecturelevel cities is also explored in this study. The results show that during 2015–2019, the annual average PM2.5 concentration level improved significantly. However, the average PM2.5 winter concentration level in 2015–2018 did not significantly decrease, with some cities showing severe pollution levels. The annual average PM2.5 of China’s prefecture-level cities exhibit club convergence, while the PM2.5 concentration in winter exhibits ‘unikurtosis’. In the long run, the annual average PM2.5 clusters around two levels, at approximately 35 lg/m3 and 60 lg/m3 , while the average PM2.5 in winter is concentrated at 100 lg/m3 . In the long run, in the central region, PM2.5 pollution is more severe than in northern and southern areas, regardless of the annual or winter average PM2.5 concentration

    The Influence of Potential Infection on the Relationship between Temperature and Confirmed Cases of COVID-19 in China

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    Considering the impact of the number of potential new coronavirus infections in each city, this paper explores the relationship between temperature and cumulative confirmed cases of COVID-19 in mainland China through the non-parametric method. In this paper, the floating population of each city in Wuhan is taken as a proxy variable for the number of potential new coronavirus infections. Firstly, to use the non-parametric method correctly, the symmetric Gauss kernel and asymmetric Gamma kernel are applied to estimate the density of cumulative confirmed cases of COVID-19 in China. The result confirms that the Gamma kernel provides a more reasonable density estimation of bounded data than the Gauss kernel. Then, through the non-parametric method based on the Gamma kernel estimation, this paper finds a positive relationship between Wuhan’s mobile population and cumulative confirmed cases, while the relationship between temperature and cumulative confirmed cases is inconclusive in China when the impact of the number of potential new coronavirus infections in each city is considered. Compared with the weather, the potentially infected population plays a more critical role in spreading the virus. Therefore, the role of prevention and control measures is more important than weather factors. Even in summer, we should also pay attention to the prevention and control of the epidemic

    Preparation and Characterization of Wood Scrimber Based on Eucalyptus Veneers Complexed with Ferrous Ions

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    Wood-based products manufactured from fast-growing wood species such as eucalyptus have gained increasing attraction with the demand of using wood in architecture, furniture, and decoration. In this paper, a new type of wood scrimber based on eucalyptus veneers complexed with ferrous ions was prepared and its properties were characterized. The results showed that the presence of complexes did not affect the mechanical properties of eucalyptus wood scrimber, but made its surface more hydrophobic (contact angle increased by 38.48% and dimensional stability improved (thickness swelling rate decreased by 32.26%). Most importantly, the color of eucalyptus wood scrimber changed significantly, from the original brown to dark blue, and its anti-photoaging property also greatly improved. These advantages would make this type of wood scrimber based on the eucalyptus veneer complexes with ferrous ions more widely applicable in decorations and buildings

    Estimation of the Hydrophobicity of a Composite Insulator Based on an Improved Probabilistic Neural Network

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    The estimation of hydrophobicity for composite insulators is of great importance for the purpose of predicting the surface degradation. The hydrophobic image is firstly decomposed by the 2-level wavelet, along with the multi-Retinex algorithm in this paper. The processed low frequency sub-band and high frequency sub-band images are then reconstructed. The 3 × 3 Sobel operator is performed to measure the basic spatial gradient in four directions, including the horizontal direction, the diagonal direction, and then the vertical direction. The shape factor, the area ratio of the largest water droplet, and the coverage rate of the water droplet are selected as the feature parameters and input into the classification network that has been trained to do the hydrophobic level recognition. The effect of the different expansion speed on the desired learning results is discussed. The threshold plays a key role in image processing. Considering that the difference between the water droplet edge and the composite insulator surface is relatively small, the asymptotic semi-soft threshold function is used in pretreatment, whereas the adaptive two-dimensional Otsu’s method is used in image segmentation. The experimental results show that the proposed method has high recognition accuracy up to 94.8% for a diversity of images, and it is superior to the improved Shape Factor Method, the Multi-fractal Method, and the RBF Neural Network

    Surface Properties of Pine Scrimber Panels with Varying Density

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    Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because the water contact angles were less than 90°. The panels with a density of 1.20 g/cm3 had the largest angle change rate (k = 0.212). As the panel density increased, the instantaneous contact angle of each test liquid (i.e., water, formamide, and diiodomethane) on the panels decreased, and so did surface free energy. Panels with higher density showed lower surface roughness. Surface roughness across the wood grain was greater than that along the grain. SEM observations showed the high-density panels had a smoother surface with fewer irregular grooves in comparison with the low-density panels. X-ray photoelectron spectroscopy (XPS) analysis indicated that more unoxygenated groups appeared on the surface of high-density panels

    Prenatal Diagnosis: The Main Advances in the Application of Identification of Biomarkers Based on Multi-Omics

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    Prenatal diagnosis is to make the diagnosis of fetal structural abnormalities, genetic diseases, and pregnancy-related diseases before birth thus could offer evidence for intrauterine treatment or selectively termination of pregnancy. Up to now, researchers have applied multi-omics, including genomics, transcriptomics, and proteomics, in the discovery of prenatal diagnostic biomarkers. They have found some candidate biomarkers for aneuploids, preeclampsia, intrauterine growth retardation, and congenital structural abnormalities. With the momentous progress of biomarkers’ identification based on multi-omics for prenatal diagnosis, noninvasive prenatal testing (NIPT) has experienced tremendous progress and is revolutionizing prenatal screening and diagnosis over the past few decades. Extensive studies have also demonstrated the value of biomarkers. In particular, cell-free DNA (cfDNA), allows for a definitive diagnosis in early pregnancy for fetal diseases, including Down syndrome and other common aneuploidies. The cfDNA can be extracted from maternal plasma, posing no risk of miscarriage compared to the traditional invasive diagnosis directly analyzing fetal cells from amniocentesis or chorionic villus sampling. In this review, we would discuss the main advances, strengths, and limitations in the application of biomarkers for prenatal diagnosis along with the analysis of several representative fetal diseases

    Full-Wood Utilization Strategy toward a Directional Luminescent Solar Concentrator

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    Luminescent solar concentrators (LSCs) have proven to be highly effective in enhancing the conversion efficiency of photovoltaic (PV) cells. However, the traditional LSCs always suffer from self-absorption and escape the losses of luminescence. To these challenges, this study presents an ingenious all-wood-based LSC (W-LSC) with directional light-concentrating capabilities. By converting lignin into fluorescent carbon quantum dots (CQDs) and integrating them into transparent cellulose channels in delignified wood, we achieved efficient directional luminescence transmission in the W-LSC is achieved. The synthesized lignin-based CQDs (L-CQDs) exhibited a large Stokes shift (0.63 eV) and a bright yellow emission (540 nm). The prepared W-LSC possessed an external optical efficiency (ηopt) along the longitudinal (L) direction of 4.60% under a low irradiation intensity (40 mW·cm–2). Besides, contributed to the low thermal conductivity (0.300 W·m–1·K–1) of wood, the W-LSC maintained an ηopt of 4.03% at a temperature of 65 °C. Furthermore, the W-LSC demonstrated high tensile strength (424 MPa) and light transmission (85%). By leveraging the advantages of wood, this approach provides a different solution for enhancing solar energy utilization and advancing sustainable building

    Chinese consumer preferences for organic labels on Oolong tea: evidence from a choice experiment

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    Repeated food scandals in China have prompted growing consumer consciousness on food safety and health. Organic food, considered to be of higher quality, is being increasingly demanded by Chinese consumers. This study examines preferences for organic labels to provide insight on the sustainable development of the Oolong tea industry. Research was conducted using the choice experiment (CE) method in Fujian and Guangdong Provinces. The results demonstrate that place of origin, organic label, and brand attributes are all significant factors affecting the purchase of Oolong. Also, people demonstrated significantly positive attitudes toward organic labels and preferred Oolong tea from Fujian Province to those from Guangdong Province and Taiwan. Increasing trust can enhance consumer preference and willingness to pay (WTP) for organic labels. Contrary to previous studies, people have a higher WTP for Chinese organic labels than Japanese and American ones. This is probably because respondents are more familiar with domestic Oolong tea and trust more in Chinese organic certification. This provides an opportunity for domestic producers to tailor their organic food labels and better satisfy consumer demands. These findings suggest that the Chinese government should take more responsibility for reducing food-related fraud and thus improve consumer trust regarding organic food
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