Using a combination of δ13CDIC-DOC-difference in dissolved inorganic and organic carbon, δ2H, and δ18O to localize leachate leaks at landfill sites in China.

The investigation of leachate leakage at numerous landfill sites is urgently needed. This study presents an exploration of environmental tracing methods using δ2H and δ13C-difference in dissolved carbon (δ13CDIC-DOC) to localize leachate leak points at landfill sites. δ2H, δ13CDIC, δ13CDOC, δ18O, and an array of physicochemical indices (e.g., total dissolved solids, temperature, and oxidation reduction potential) were monitored in both leachate and groundwater from different zones of a landfill site in China during the year of 2021-2023. Moreover, data for these parameters (i.e., the isotopic composition and physicochemical indices) from twelve published landfill cases were also collected, and these groundwater/leachate data points were located within 1 km away from the landfill boundary. Then statistical analyses, such as Pearson correlation analysis and redundancy analysis (RDA), were performed using both the detected and collected parameters at landfill sites. Consequently, the intensity of interaction between leachate and background groundwater was found to significantly control the isotopic fractionation features of hydrogen and carbon, and both the content of major contamination indicators (total dissolved solids, chemical oxygen demand, and ammoniacal nitrogen) and the oxidation reduction potential were the key impact factors. Accordingly, the water type used to indicate leachate leakage points was determined to be leachate that significantly interacted with the background groundwater or precipitation (LBGP). δ2H showed a perfect linear correlation (0.81 ≤ r2 < 1.0) with δ13CDIC-DOC in leachate under highly anaerobic landfill conditions, and the δ2H & δ13CDIC-DOC combinations in the LBGP were significantly different from those in the other water types. For groundwater with total dissolved solids lower than 1400 mg/L at landfill sites, a strong positive linear correlation (r = 0.83) was revealed between δ13CDIC and δ13CDOC. Based on these insights, δ2H versus δ13CDIC-DOC plots and RDA using δ2H and δ13CDIC-DOC as response variables were proposed to localize leak points at both lined landfills and leachate facilities. These findings further understanding of the isotopic fractionation features of hydrogen, carbon, and oxygen and provide novel environmental tracer methods for investigating leachate leak points at MSW landfill sites.

Tracking groundwater pollution plumes at landfill sites using borehole hydrochemical and hydrodynamic profile (BHHP) method.

Groundwater pollution at landfill sites poses a significant risk to human health and ecological security. However, efficiently tracking pollution plumes in a polluted aquifer with variable pollutants remains challenging. In order to track groundwater pollution plumes at landfill sites, an in-situ borehole hydrochemical and hydrodynamic profile (BHHP) method was developed. Total dissolved solids (TDS), oxidation-reduction potential (ORP), and ammonia nitrogen were selected as the hydrochemical indicators. Meanwhile, the hydrodynamic indicators included flow direction and flow velocity of groundwater. Among the three hydrochemical indicators, TDS and ORP were analyzed to be the prior alternative ones for the BHHP application. The BHHP method was successfully applied to track groundwater pollution plumes at a typical valley-type landfill site and its neighboring downstream zone. Consequently, four groundwater pollution plumes of different types and different scales were identified in both horizontal and vertical directions within the depth of 0-50 m, and the various pollution sources for the detected pollution plumes were revealed. Furthermore, the BHHP method was validated using sampling test results of groundwater chloride and chemical oxygen demand at the surveyed landfill site.

Mechanism of vascular endothelial cell-derived exosomes modified with vascular endothelial growth factor in steroid-induced femoral head necrosis.

Steroid-induced avascular necrosis of the femoral head (SANFH) is an intractable orthopedic disease. This study investigated the regulatory effect and molecular mechanism of vascular endothelial cell (VEC)-derived exosomes (Exos) modified with vascular endothelial growth factor (VEGF) in osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in SANFH. VECs were culturedin vitroand transfected with adenovirus Adv-VEGF plasmids. Exos were extracted and identified.In vitro/vivoSANFH models were established and treated with VEGF-modified VEC-Exos (VEGF-VEC-Exos). The internalization of Exos by BMSCs, proliferation and osteogenic and adipogenic differentiation of BMSCs were determined by the uptake test, cell counting kit-8 (CCK-8) assay, alizarin red staining, and oil red O staining. Meanwhile, the mRNA level of VEGF, the appearance of the femoral head, and histological analysis were assessed by reverse transcription quantitative polymerase chain reaction and hematoxylin-eosin staining. Moreover, the protein levels of VEGF, osteogenic markers, adipogenic markers, and mitogen-activated protein kinase (MAPK)/extracellular regulated protein kinases (ERK) pathway-related indicators were examined by Western blotting, along with evaluation of the VEGF levels in femur tissues by immunohistochemistry. Glucocorticoid (GC) induced adipogenic differentiation of BMSCs and inhibited osteogenic differentiation. VEGF-VEC-Exos accelerated the osteogenic differentiation of GC-induced BMSCs and inhibited adipogenic differentiation. VEGF-VEC-Exos activated the MAPK/ERK pathway in GC-induced BMSCs. VEGF-VEC-Exos promoted osteoblast differentiation and suppressed adipogenic differentiation of BMSCs by activating the MAPK/ERK pathway. VEGF-VEC-Exos accelerated bone formation and restrained adipogenesis in SANFH rats. VEGF-VEC-Exos carried VEGF into BMSCs and motivated the MAPK/ERK pathway, thereby promoting osteoblast differentiation of BMSCs in SANFH, inhibiting adipogenic differentiation, and alleviating SANFH.

Application of Multimodal Fusion Technology in Image Analysis of Pretreatment Examination of Patients with Spinal Injury.

As one of the most common imaging screening techniques for spinal injuries, MRI is of great significance for the pretreatment examination of patients with spinal injuries. With rapid iterative update of imaging technology, imaging techniques such as diffusion weighted magnetic resonance imaging (DWI), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and magnetic resonance spectroscopy are frequently used in the clinical diagnosis of spinal injuries. Multimodal medical image fusion technology can obtain richer lesion information by combining medical images in multiple modalities. Aiming at the two modalities of DCE-MRI and DWI images under MRI images of spinal injuries, by fusing the image data under the two modalities, more abundant lesion information can be obtained to diagnose spinal injuries. The research content includes the following: (1) A registration study based on DCE-MRI and DWI image data. To improve registration accuracy, a registration method is used, and VGG-16 network structure is selected as the basic registration network structure. An iterative VGG-16 network framework is proposed to realize the registration of DWI and DCE-MRI images. The experimental results show that the iterative VGG-16 network structure is more suitable for the registration of DWI and DCE-MRI image data. (2) Based on the fusion research of DCE-MRI and DWI image data. For the registered DCE-MRI and DWI images, this paper uses a fusion method combining feature level and decision level to classify spine images. The simple classifier decision tree, SVM, and KNN were used to predict the damage diagnosis classification of DCE-MRI and DWI images, respectively. By comparing and analyzing the classification results of the experiments, the performance of multimodal image fusion in the auxiliary diagnosis of spinal injuries was evaluated.