Spatial relationships between forest and PM2.5 concentrations are of great policy implications in regional afforestation layout and air pollution control. This paper investigates the transboundary ...externality of a city’s forest on the concentrations of PM2.5 in different city segments. Employing a mixed-regressive spatial panel model with data for 255 Chinese cities over 2000 to 2015, we find that the concentrations of PM2.5 tend to be substantially lower in cities with larger forest area and the depositing effect of forest spills over significantly to neighboring cities. A one percentage increase in forest area reduces the average annual concentrations of PM2.5 by 2.53%, of which 76% is contributed to the spillover effect. Moreover, the average marginal effect of forest on PM2.5 concentrations exhibits an inverted-U relationship with wind speed and the depositing effect minimizes (in magnitude) as the average annual speed of wind approaches to 23 kilometers per hour. These findings suggest that severe hazing cities with mild wind speed are priority afforestation areas for transboundary air pollution control.
•We quantified the own and spillover effects of forest on PM2.5 concentrations with a panel dataset of 255 Chinese cities over 2000 to 2015.•The concentrations of PM2.5 tend to be substantially lower in cities with larger forest area and the effect spills over significantly to neighboring cities.•PM2.5 concentrations in a city are more heavily affected by an average increase in forest area of its neighbors.•The depositing effect of forest on PM2.5 minimizes (in magnitude) as the average annual wind speed approaches to 23 km per hour.
•The Trans-deformer module is proposed to solve the deformation of the pancreas.•The Scale Inter-active Fusion module is designed to integrate local features and global features.•The multi-input ...module based on wavelet decomposition is put forward for blurred boundaries of the pancreas.•The effectiveness of the Trans-Deformer network is validated on two public pancreas datasets.
Accurate and efficient pancreas segmentation is the basis for subsequent diagnosis and qualitative treatment of pancreatic cancer. Segmenting the pancreas from abdominal CT images is a challenging task because the morphology of the pancreas varies greatly among different individuals and may be affected by problems such as the unbalanced category and blurred boundaries. This paper proposes a two-stage Trans-Deformer network to solve these problems of pancreas segmentation. To be specific, we first use 2D Unet for coarse segmentation to generate candidate regions of the pancreas. In the fine segmentation stage, we propose to integrate deformable convolution into Vision Transformer (VIT) for solving the deformation problem of the pancreas. For the problem of blurred boundaries caused by low contrast in the pancreas, a multi-input module based on wavelet decomposition is proposed to make our network pay more attention to high-frequency texture information. In addition, we propose using the Scale Inter-active Fusion (SIF) module to merge local features and global features. Our method was evaluated on the public NIH dataset including 82 abdominal contrast-enhanced CT volumes and the public MSD dataset including 281 abdominal contrast-enhanced CT volumes via fourfold cross-validation. We have achieved the average Dice Similarity Coefficient (DSC) values of 89.89 ± 1.82 % on the NIH dataset, and 91.22 ± 1.37 % on the MSD dataset, outperforming other exiting state-of-the-art pancreas segmentation methods.
To gain a deep understanding of the interaction between underground mining and mountain deformation, based on historical deformation and the UAV video, we analyzed the evolution process of ...deformation and failure in detail and comprehensively evaluated the slope deformation and fracture network under the action of underground mining via the bottom friction physical simulation test, DPDM technology, fractal theory, and percolation theory. We simulated the whole process of mining, deformation, and failure of the Pusa collapse. DPDM technology was employed to obtain the evolution process of the total displacement, maximum shear strain (
γ
max
), and volumetric strain
ε
v
of the Pusa collapse and establish a relationship between the fractal dimension and settlement. Simultaneously, the fractal dimension, fracture number, fracture rate, and percolation probability of the fracture network were calculated in MATLAB software. The research results of the bottom friction physical simulation test and DPDM technology indicated that after the M10 coal seam was mined, the maximum total displacement and maximum shear strain
γ
max
were mainly located in the direct roof, resulting in volume expansion due to the direct roof collapse. After the M14 coal seam was mined, the maximum total displacement and volume strain
ε
v
developed towards the slope top, and the maximum shear strain was located in the middle and lower parts of the model surface and the leading and trailing edges of the slope top, respectively. The research results of fractal dimension and percolation probability indicated that after the M10 coal seam was mined, the development form of the fracture network at this stage mainly entailed the formation of new fractures. After the M14 coal seam was mined, the fracture network developed from beyond this stage mainly included fracture expansion and opening. The test results are consistent with the historical change process and the UAV video showing the method and signs of deformation. These research results help to better explain the deformation evolution process of a given slope under the action of underground mining and provide a technical reference for accurate assessment and proper mitigation of similar landslide disasters.
To tackle the energy consumption issue and meet the energy-efficiency building requirement, this study proposes a method by incorporating polyethylene (PE) powder as a multi-function and low-cost ...construction material in the foam concrete to enhance the thermal insulation. The effects of heating treatment and dosages of PE powder on the dry density, compressive strength, water absorption, thermal conductivity and microstructure of foam concrete were investigated. The pore structure and morphology were examined using Image-Pro-Plus software, electron microscope and SEM-EDS. Results indicate that the dry density and compressive strength of foam concrete generally decreased, while the water absorption overall increased with higher dosage of PE powder. Thermal conductivity of foam concrete containing PE powder without heating treatment exhibited a rising trend with the increase of dosage, while that of foam concrete prepared with the PE powder was greatly inhibited by heating treatment. Both the average roundness of pores and the porosity of foam concrete increased with the incorporation of PE powder, but the smaller effective pore size in the foam concrete with heating treatment was significant. The PE membrane coated on the pore wall and clogged the pore structure, which was verified by SEM-EDS analysis on the microstructure of foam concrete after heating treatment.
•Polyethylene (PE) powder can be added into foam concrete.•PE powder with higher dosage has a deterioration on the strength and water absorption.•PE powder after heating treatment is effective inhibiting the thermal conductivity.•PE powder after heating treatment refines effective pore size but increases porosity.•The PE membrane is coated on the pore wall and clogged the pore structure.
The quality of red blood cells (RBCs) in stored blood has a direct impact on the recovery of patients treated by blood transfusion, which directly reflects the quality of blood. The traditional means ...for blood quality evaluation involve the use of reagents and multi-step and time-consuming operations. Here, a low-cost, multi-classification, label-free and high-precision method is developed, which combines microfluidic technology and a deep learning algorithm together to recognize and classify RBCs based on morphology. The microfluidic channel is designed to effectively and controllably solve the problem of cell overlap, which has a severe negative impact on the identification of cells. The object detection model in the deep learning algorithm is optimized and used to recognize multiple RBCs simultaneously in the whole field of view, so as to classify them into six morphological subcategories and count the numbers in each subgroup. The mean average precision of the developed object detection model reaches 89.24%. The blood quality can be evaluated by calculating the morphology index (MI) according to the numbers of cells in subgroups. The validation of the method is verified by evaluating three blood samples stored for 7 days, 21 days and 42 days, which have MIs of 84.53%, 73.33% and 24.34%, respectively, indicating good agreement with the actual blood quality. This method has the merits of cell identification in a wide channel, no need for single cell alignment as the image cytometry does and it is not only applicable to the quality evaluation of RBCs, but can also be used for general cell identifications with different morphologies.
The precise segmentation of brain tumor images is a vital step towards accurate diagnosis and effective treatment of brain tumors. Magnetic Resonance Imaging (MRI) can generate brain images without ...tissue damage or skull artifacts, providing important discriminant information for clinicians in the study of brain tumors and other brain diseases. In this paper, we survey the field of brain tumor MRI images segmentation. Firstly, we present the commonly used databases. Then, we summarize multi-modal brain tumor MRI image segmentation methods, which are divided into three categories: conventional segmentation methods, segmentation methods based on classical machine learning methods, and segmentation methods based on deep learning methods. The principles, structures, advantages and disadvantages of typical algorithms in each method are summarized. Finally, we analyze the challenges, and suggest a prospect for future development trends.
This study aims to explore the feasibility of foamed cement preparation by microbial liquid. Specimens containing glass beads were employed for comparison with microbial foamed cement, and the ...characterization and evaluation of these samples were conducted using techniques such as TGA, XRD, micro-CT, thermal conductivity measuring instrument and SEM. The results revealed that the porosity of the microbial foamed specimens could reach 25.3 %, and compared to the thermal conductivity of 1.06 W/mK for the normal samples, microbial foamed cement could reach 0.58 W/mK. Furthermore, the strength of the foamed cement with bacterial solution was the lowest, and the strength at 7 days was almost the same as that at 28 days. This is attributed to the high concentration of the bacterial solution impacting the stabilization of the C-S-H gel, thereby hindering the further hydration of cement particles. Nevertheless, for production blocks used in non-load-bearing structures, the strength proved to be adequate, and significant time savings can be achieved.
•The feasibility of making foamed cement with microbial assisted foaming was investigated.•The influence of bacterial solution on the strength of cement was clarified.•The pore structure generated by microbial foaming was observed.
The seismic performance of prefabricated reinforced concrete shear walls is a key point in the safety of the whole assembly structure under earthquake actions. In this study, six specimens of ...reinforced concrete shear walls were assembled with a cast-in-place vertical joint with a straight, L, or convex shape. The specimens were tested using a low cyclic loading test under an axial compression ratio of 0.2 or 0.3. The stress process, failure pattern, and hysteretic curve of each specimen were measured. Combined with a numerical analysis using the finite element method, the variations in the bearing capacity, stiffness degradation, ductility, and energy dissipation capacity of the tested specimens were analyzed. Results showed that all specimens failed in a shear pattern without an obvious failure phenomenon along the vertical joint. The hysteresis curves exhibited an obvious pinch phenomenon and good deformation ability. The seismic behavior decreased in sequence for the shear walls assembled with a cast-in-place vertical joint with a straight, L, or convex shape, while a higher axial compression ratio improved the bearing capacity of the shear walls. The shear wall with an L-shaped vertical joint had similar seismic behavior to that with a straight vertical joint, but the shear wall with a convex vertical joint exhibited a decrease of 8.5% and 10.9% in bearing capacity, 18.2% and 1.2% in ductility, and 13.1% and 20.6% in energy dissipation, respectively, under an axial compression ratio of 0.2 and 0.3. The bearing mechanisms of shear walls with different vertical joints are explained with the numerical analysis of the stress vector maps of concrete and the stress cloud maps of reinforcements at different stress levels.
Circulating tumor cells (CTCs), which have extremely low density in whole blood, are an important indicator of primary tumor metastasis. Isolation and enumeration of these cells are critical for ...clinical applications. Separation of CTCs from massive blood cells without labeling and addition of synthetic polymers is challenging. Herein, a novel well-defined co-flow microfluidic device is presented and used to separate CTCs in viscous blood by applying both inertial and viscoelastic forces. Diluted blood without any synthetic polymer and buffer solution were used as viscoelastic fluid and Newtonian fluid, respectively, and they were co-flowed in the designed chip to form a sheath flow. The co-flow system provides the function of particle pre-focusing and creates a tunable shear rate region at the interface to adjust the migration of particles or cells from the sample solution to the buffer solution. Successful separation of CTCs from viscous blood was demonstrated and enumeration was also conducted by image recognition after separation. The statistical results indicated that a recovery rate of cancer cells greater than 87% was obtained using the developed method, which proved that the direct separation of CTCs from diluted blood can be achieved without the addition of any synthetic polymer to prepare viscoelastic fluid. This method holds great promise for the separation of cells in viscous biological fluid without either complicated channel structures or the addition of synthetic polymers.
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•Granites and related Sn mineralization are coeval at ~150 Ma.•Dayishan A-type granites are formed from the crustal-mantle interaction.•Dayishan granites are in favor of Sn ...mineralization.
The roles of the mantle in generating granites and the extent of crust-mantle interaction are fundamental topics to our understanding of Sn mineralization. In this study, we report geochronological, geochemical, and Sr-Nd–Hf isotopic data for the granites, and muscovite 40Ar/39A isotopic data of the greisen type Sn ores, in the Dashunlong Sn deposit, Dayishan orefield, middle Qinzhou-Hangzhou metallogenic belt. LA–ICP–MS zircon U–Pb dating for the medium-fine grained- and coarse grained-biotite monzogranite of Dayishan pluton yields emplacement ages of 154.6 ± 1.2 Ma (MSWD = 0.73) and 154.7 ± 1.6 Ma (MSWD = 1.9), respectively, which are consistent with the muscovite 40Ar/39Ar plateau age of 151.1 ± 0.9 Ma (MSWD = 0.09) for the greisen-type Sn ores. It is indicated that the Sn mineralization in the Dashunlong deposit is related to the Late Jurassic Dayishan granite. The granite shows the geochemical features of highly fractionated A-type granite: 1) high 10,000 Ga/Al ratios of 2.95–3.88; 2) high Zr + Nb + Ce + Y contents of 292–637 ppm; 3) high TFeO/(TFeO* + MgO) ratios of 0.86–0.97; and 4) high Rb/Sr ratios of 2.80–18.8. Whole rocks isotopes show that this granite has variable initial 87Sr/86Sr ratios (0.71607–0.72437), negative εNd(t) values (−7.20 to −5.46), and two-stage Nd model ages of 1530–1388 Ma. LA–MC–ICP–MS zircon Lu-Hf isotopes show that the medium-fine-grained monzogranite has εHf(t) values of −0.94–2.20 and two-stage Hf model ages of 1298–1059 Ma, whereas the coarse-grained biotite monzogranite has relatively high εHf(t) values of −0.84–5.95 and two-stage Hf model ages of 1257–823 Ma. Different Hf and Nd isotopes indicate that the Nd-Hf isotopic decoupling occurs in the Dayishan granite, which was likely caused by the partial melting of the rocks containing abundant high Lu/Hf minerals. The magma of the Dayishan granite is reduced, highly fractionated, and enriched in Sn and F, resulting in large-scale Sn mineralization in the Dayishan orefield. It is proposed that these granites are originated from melts mixed by crustal- and mantle constituents and are formed in an extensional setting caused by the subduction of the Palaeo-pacific plate. A two end-member modeling indicates that ca. 10–20 percent of mantle-derived melts were likely involved in the formation of the Dayishan granites.
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