TrajStat: GIS-based software that uses various trajectory statistical analysis methods to identify potential sources from long-term air pollution measurement data

Statistical analysis of air mass back trajectories combined with long-term ambient air pollution measurements are useful tools for source identification. Using these methods, the geographic information system (GIS) based software, TrajStat, was developed to view, query, and cluster the trajectories and compute the potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses when measurement data are included.     

Improved GDP spatialization approach by combining land-use data and night-time light data: a case study in China’s continental coastal area

Gross domestic product (GDP) reflects a nation or region’s economic growth as a whole, and is the sum of product in the primary, secondary, and tertiary sectors of the economy in the area. However, statistical GDP data is problematic in integrated application with geographical data. The GDP spatialization data, which shows the GDP in grid cells and often is obtained by operating a spatialization model, is more useful than its officially published statistical data recorded by administrative units in both spatial representation and application. Thus, there is a need to improve the GDP spatialization models, and to present these models in a way as clear and transparent as possible. In this article, by taking China’s continental coastal area as a case study area, we combined economic census data, land-use data, and night-time light data together, and developed a technique that we call the ‘dynamic regionalization’ method to improve the GDP spatialization products. We then created GDP spatialization models for three sectors of the economy (i.e. the primary, the secondary, and the tertiary sector) in 2000, 2005, and 2010, respectively. We find the following. (1) Because the ‘overglow’ effect of night-time light data has a bad influence on spatialization models, we used land-use data to distinguish the distribution plots of the tertiary sector on night-time light images. Compared with setting a threshold merely, land-use data can more effectively remove the ‘overglow’ effect. (2) Owing to the prominent spatial heterogeneity of GDP distribution in China’s continental coastal area, building one spatialization model for the whole area would probably produce the estimated products with poor accuracy, so the ‘dynamic regionalization’ method was adopted to dynamically divide the whole study area into several subregions, and build separate spatialization models for each subregion. The accuracy assessment showed that the new method improved the accuracy of GDP spatialization data, especially in the area with high spatial heterogeneity.     

Heavy metal pollution status in surface sediments of the coastal Bohai Bay

Bohai Bay, the second largest bay of Bohai Sea, largely due to the huge amount of pollutants discharged into it annually and its geohydrologic condition, is considered to be one of the most polluted marine areas in China. To slow down, halt and finally reverse the environmental deterioration of Bohai Sea, some researchers have proposed to connect it with Jiaozhou Bay in the western coast of Southern Yellow Sea by digging an interbasin canal through Shandong Peninsula. In order to assess the heavy metal pollution and provide background information for such a large geoengineering scheme, surface sediments from 42 stations covering both riverine and marine regions of the northwestern coast of Bohai Bay were analyzed for heavy metal content and fractionation (Cd, Cr, Cu, Ni, Pb and Zn). Three empirically derived sediment quality guidelines were used to assess the pollution extent of these metals. The studied metals had low mobility except for Cd at all stations and Zn at some riverine stations. Although a high mobility of Cd was observed, it could hardly cause a bad effect on the environment owing to its low total concentrations. Anthropogenic influence on the accumulation of studied heavy metals in sediments of Bohai Bay was obvious, but their contents were relatively lower to date comparing with some other marine coastal areas that receive important anthropogenic inputs. Taking as a whole, surface sediments of northwestern Bohai Bay had a 21% probability of toxicity based on the mean effects range-median quotient.     

Reconstruction of satellite chlorophyll-a data using a modified DINEOF method: a case study in the Bohai and Yellow seas,China

A data-interpolating empirical orthogonal function (DINEOF) method was applied to 8 day composited satellite-derived chlorophyll-a (chl-a) images to produce a long-term, cloud-free chl-a data set over the Bohai Sea and Yellow Sea from 1997 to 2010. In this study, two additional procedures, a depth subdivision scheme and a new process of outlier detection and removal, improved the overall performance of this interpolating technique. The whole chl-a data set was divided into three subsets according to 20 and 50 m isobaths and the DINEOF reconstruction was performed on each subset. This subdivision scheme can significantly improve the accuracy of reconstruction, but is achieved with loss of computational efficiency due to the increased number of iterations required for reconstruction of the three subsets. A simple and new outlier detection method based on standardized residuals theory was developed to eliminate the spurious values (outliers) from the chl-a data set. The accuracy of the DINEOF reconstruction was significantly improved by the application of the outlier detection and removal process.     

Templated electrodeposition of Ag7NO11 nanowires with very high oxidation states of silver

The templated electrodeposition of 200 nm diameter nanowires of the argentic oxynitrate Ag(Ag₃O₄)₂NO₃ phase is reported. Their high surface-to-volume ratio and the high average oxidation state of Ag make these wires promising candidates for nanoscale redox processes in which both a high volumetric charge density and a high discharge rate are required. The antibiotic activity of these nanowires was demonstrated by inhibiting the growth of Bacillus cereus bacteria.     

N-doped hierarchically macro/mesoporous carbon with excellent electrocatalytic activity and durability for oxygen reduction reaction

A novel kind of N-doped hierarchically porous carbon materials (HPC-Ns) has been successfully synthesized with hierarchically macro/mesoporous silica as a hard template followed by a simple N-doping procedure using low-cost and nontoxic urea as the nitrogen source. The synthesized HPC-N samples demonstrated extensive three-dimensional (3D) connected macroporosity and partially ordered mesoporosity, extremely large specific surface area, favorable graphitization degree, and high relative content of pyridinic N, which is active to the oxygen reduction reaction (ORR). Due to the combined contributions of the above features, the metal-free HPC-Ns demonstrated excellent performance in ORR with a highly comparable limiting current density but much higher current output stability and resistance towards the fuel crossover effect compared to the commercial Pt/C, as well as the dominant 4 e⁻ reduction mechanism. Thus, it is believed that HPC-N has the potential to be used in polymer electrolyte membrane fuel cells.     

Reproducible and Sensitive Plasmonic Sensing Platforms Based on Au-Nanoparticle-Internalized Nanodimpled Substrates

Electromagnetic enhancement effects through localized surface plasmon resonance considerably amplify the intensity of incident light when molecules are positioned in the vicinity of miniscule nanogaps. The aggregation of plasmonic nanoparticles synthesized using bottom-up methods has been extensively used to generate hot spots in solutions. These methods assist in obtaining non-periodic plasmonic signals, because the realization of uniform nanogaps through particle aggregation is difficult. Nanostructured substrates with gaps of 20–100 nm have also been fabricated using the top-down approach. However, the fabrication of smaller nanogap templates using these methods is difficult owing to high costs and low throughput. Therefore, a nanodimple array internalized with AuNPs is developed in this study to mitigate the challenges encountered in the bottom-up and top-down approaches. Precise nanogaps are generated by regularly internalizing AuNPs in the cavities of nanodimples through DNA hybridization. Simulations of the electric field distribution indicate that the incorporation of 80 nm-sized AuNPs into a curved nanodimpled Au substrate generate high-density volumetric hot spots within a detection volume, and result in a high plasmonic enhancement factor of 8.25 × 10⁷. The tremendous potential of the proposed plasmonic platform as an SERS-based biomedical diagnostic device is also verified.     

基于激光偏振技术的海洋牧场水下成像技术研究

良好的水下视觉环境是推动海洋经济发展的前提,海洋牧场的建设对水下成像技术提 出 新的要求,但是受水体环境吸收及散射影响,光信息丢失严重,用常规光学成像方式进行水 下 图像获取会有可视距离短,图像模糊不清,对比度低等缺点。为解决海洋牧场水下成像清晰 度 低的问题,提出一种通过532 nm激光光源与偏振技术相结合的方法并 集成了一款水下相机。 532 nm波段的绿色激光光源在水体环境中受到水体影响较小,传播效 果更佳,偏振成像技术在去 背景光散射中应用广泛,采用532 nm激光光源与偏振成像技术相结合 的方法进行水下图像的获 取,并在模拟海水环境的水池中进行了海参图像获取的实验,实验结果证明在某一偏振角度 下, 532 nm激光光源与偏振成像技术相结合的方式获取的海参图像相比于 自然光下获取的原图像对比 度、清晰度更高,含有的图像信息更加丰富,验证了此方法在水下成像的可行性。     

Graphene quantum dots in alveolar macrophage: uptake-exocytosis,accumulation in nuclei,nuclear responses and DNA cleavage

Background

Given the tremendous potential for graphene quantum dots (QDs) in biomedical applications, a thorough understanding of the interaction of these materials with macrophages is essential because macrophages are one of the most important barriers against exogenous particles. Although the cytotoxicity and cellular uptake of graphene QDs were reported in previous studies, the interaction between nuclei and the internalized graphene QDs is not well understood. We thus systematically studied the nuclear uptake and related nuclear response associated with aminated graphene QDs (AG-QDs) exposure.

Results

AG-QDs showed modest 24-h inhibition to rat alveolar macrophages (NR8383), with a minimum inhibitory concentration (MIC) of 200 μg/mL. Early apoptosis was significantly increased by AG-QDs (100 and 200 μg/mL) exposure and played a major role in cell death. The internalization of AG-QDs was mainly via energy-dependent endocytosis, phagocytosis and caveolae-mediated endocytosis. After a 48-h clearance period, more than half of the internalized AG-QDs remained in the cellular cytoplasm and nucleus. Moreover, AG-QDs were effectively accumulated in nucleus and were likely regulated by two nuclear pore complexes genes (Kapβ2 and Nup98). AG-QDs were shown to alter the morphology, area, viability and nuclear components of exposed cells. Significant cleavage and cross-linking of DNA chains after AG-QDs exposure were confirmed by atomic force microscopy investigation. Molecular docking simulations showed that H-bonding and π-π stacking were the dominant forces mediating the interactions between AG-QDs and DNA, and were the important mechanisms resulting in DNA chain cleavage. In addition, the generation of reactive oxygen species (ROS) (e.g., ?OH), and the up-regulation of caspase genes also contributed to DNA cleavage.

Conclusions

AG-QDs were internalized by macrophages and accumulated in nuclei, which further resulted in nuclear damage and DNA cleavage. It is demonstrated that oxidative damage, direct contact via H-bonding and π-π stacking, and the up-regulation of caspase genes are the primary mechanisms for the observed DNA cleavage by AG-QDs.