Control mechanism of the migration of heavy metal ions from gangue backfill bodies in mined-out areas

In the process of solid backfill mining, the leaching of heavy metal ions from the gangue backfill body in the mined-out area can pose potential risk of polluting water resources in the mine. Accordingly, based on the environment of the gangue backfill body, the migration model of heavy metal ions from the gangue backfill body was established to reveal the pollution mechanism of water resources by the gangue backfill body in the mined-out area. The main factors that affect the migration of heavy metal ions were analyzed, and prevention and control techniques for the leaching and migration of heavy metal ions from gangue backfill bodies were proposed. Research showed that the heavy metal ions in gangue backfill bodies were subjected to the coupled action of seepage, concentration, and stress and then driven by water head pressure and gravitational potential energy to migrate downward along the pore channels in the floor, during which mine water served as the carrier. The migration distance of heavy metal ions increased with time. According to the migration rate, the migration process can be subdivided into three phases: the rapid migration phase (0–50 years), the slow migration phase (50–125 years), and the stable phase (125–200 years). It was concluded that the leaching concentration of heavy metal ions, the particle size of gangue, the permeability of floor strata, and the burial depth of coal seams were the main influencing factors of the migration of heavy metal ions. From the two perspectives of heavy metal ion leaching and migration, prevention and control techniques for the leaching and migration of heavy metal ions from gangue backfill bodies were proposed to protect water resources in mining area. The present study is of great significance to realizing utilization of solid waste in mines and protecting the ecological environment

Highly parallel and efficient single cell mRNA sequencing with paired picoliter chambers

单细胞转录组测序技术在单个细胞水平上对转录组进行高通量测序分析，从而揭示单个细胞内所有基因的表达情况，揭示细胞间的异质性，在发育生物学、免疫学、微生物学、神经科学、临床医学等领域有重要的应用前景。单细胞转录组测序的挑战在于如何高效地操控单个细胞，如何对大量的低拷贝数mRNA进行无偏倚扩增，如何避免背景游离mRNA的污染，以及如何同时对大量的单细胞进行并行测序以降低成本。化学化工学院杨朝勇教授课题组在高通量单细胞转录组测序新器件新方法研究方面取得重要进展.该工作由厦门大学、上海交通大学、美国斯坦福大学等多团队联合攻关完成。化学生物学系博士研究生张明霞、邹远和2011协同创新中心博士研究生许醒为论文的共同第一作者。ScRNA-seq has the ability to reveal accurate and precise cell types and states. Existing scRNA-seq platforms utilize bead-based technologies uniquely barcoding individual cells, facing practical challenges for precious samples with limited cell number. Here, we present a scRNA-seq platform, named Paired-seq, with high cells/beads utilization efficiency, cell-free RNAs removal capability, high gene detection ability and low cost. We utilize the differential flow resistance principle to achieve single cell/barcoded bead pairing with high cell utilization efficiency (95%). The integration of valves and pumps enables the complete removal of cell-free RNAs, efficient cell lysis and mRNA capture, achieving highest mRNA detection accuracy (R = 0.955) and comparable sensitivity. Lower reaction volume and higher mRNA capture and barcoding efficiency significantly reduce the cost of reagents and sequencing. The single-cell expression profile of mES and drug treated cells reveal cell heterogeneity, demonstrating the enormous potential of Paired-seq for cell biology, developmental biology and precision medicine.The authors thank the National Science Foundation of China (21927806, 21735004, 21521004, 21325522), the National Key R&D Program of China (2018YFC1602900), Innovative research team of high-level local universities in Shanghai, and the Program for Changjiang Scholars and Innovative Research Team in University (IRT13036) for their financial support.该研究工作得到国家重大科研仪器研制项目、国家基金委重点项目、创新研究群体项目等支持

Genomic Mutation Profile of Primary Gastrointestinal Diffuse Large B-Cell Lymphoma.

Primary gastrointestinal diffuse large B-cell lymphoma (GI-DLBCL) is the most common gastrointestinal lymphoma, but its genetic features are poorly understood. We performed whole-exome sequencing of 25 primary tumor samples from patients with GI-DLBCL and 23 matched normal tissue samples. Oncogenic mutations were screened, and the correlations between genetic mutations and clinicopathological characteristics were analyzed. Twenty-five patients with GI-DLBCL were enrolled in the genetic mutation analysis with a median of 184 (range 79-382) protein-altering variants per patient. We identified recurrent oncogenic mutations in GI-DLBCL, including those in TP53, MUC16, B2M, CCND3, HIST1H1C, NEB, and ID3. Compared with nodal DLBCL, GI-DLBCL exhibited an increased mutation frequency of TP53 and reduced mutation frequencies of PIM1, CREBBP, BCL2, KMT2D, and EZH2. Moreover, GI-DLBCL exhibited fewer MYD88 and CD79B mutations than DLBCL in the testis and central nervous system. GI-DLBCLs with HLA-B, MEF2A, RHOA, and NAV3 mutations exhibited a tendency toward a high proliferation index. MUC16 and ETV6 mutations often occurred in tumors with early clinical staging. Our data provide a comprehensive understanding of the landscape of mutations in a small subset of GI-DLBCLs. The genetic mutation profiles of GI-DLBCL differ from those of nodal DLBCL and DLBCL in immune-privileged sites. The different mutated genes are related to the NF-κB and JAK-STAT pathways, and the different pathogenetic mechanisms leading to the development of DLBCL may be influenced by the tissue microenvironment. Differences in genetic alterations might influence the clinicopathological characteristics of GI-DLBCL

Influence of reservoir heterogeneity on immiscible water-alternating-CO2 flooding: A case study

Currently, limited studies of immiscible water-alternating-CO2 (imWACO2) flooding focus on the impact of reservoir heterogeneity on reservoir development outcomes. Given this, using the heterogeneous reservoirs in the Gao 89-1 block as a case study, this study conducted slab core flooding experiments and numerical simulations to assess the impact of reservoir heterogeneity on imWACO2 flooding efficiency. It can be concluded that imWACO2 flooding can enhance the sweep volume and oil recovery compared to continuous CO2 flooding. As the permeability difference increases, the difference in the swept volume between zones/layers with relatively high and low permeability increases. To optimize the exploitation of reservoirs in the Gao 89-1 block, the optimal timing and CO2 injection rate for imWACO2 flooding are determined at water cut of 40% and 10000 m³/d, respectively. A short injection-production semi-period, combined with multiple cycles of water and CO2 injection alternations, is beneficial for enhanced oil recovery from imWACO2 flooding

Sand Blocking Mechanisms and Productivity Analysis of Slant Well in Siltstone Reservoirs

The siltstone reservoir with many small layers of pay zones is usually produced by slant holes. However, severe sand blockages take place when the siltstone reservoir is developed by slant holes. Currently, the sand blocking mechanisms and the effect of sand blocking on productivity of slant well are still challenges for engineers and scholars. In this paper, based on the existing productivity model of inclined slant wells, the mechanical skin factor, which describes the effect of sand blocking on productivity, is proposed. Meanwhile, many experimental works have been done to investigate the sand blocking mechanisms in siltstone reservoirs. From the experimental work, it is concluded that with the increase of displacement PV number and displacement flow rate, the permeability of sand control system decreases by 40%. When solid particles enter the casing and block the gravel and sand control screen in the annulus, the skin factor increases sharply and the productivity decreases by more than 80%. Through the productivity calculation of multilayer sand control wells, it is considered that larger gravel packing radius can keep particles away from the well bore, which is helpful to ensure oil well productivity. Furthermore, the influence of differential filling radius on the fluid production capacity of each layer of sand control well is analyzed. It is proved that optimizing the filling radius of each layer can improve the production effect of mediate- and low-permeability layers. This method has been applied in Kendong #12 block. The daily oil production rate is increased by 9.61 t/day, and the oil recovery of this block is increased by 2.12%

Well Testing Model of Multiple Fractured Horizontal Well with Consideration of Stress-Sensitivity and Variable Conductivity in Tight Gas Reservoirs

Multiple fractured horizontal wells have been widely used to develop unconventional tight gas reservoirs. Currently, many well testing models were established to study the performance of fractured horizontal wells in tight gas reservoirs. However, none of these models thoroughly takes stress-sensitivity of natural fractures and variable conductivity of artificial fractures into consideration. Based on the consideration of stress-sensitivity of natural fractures and variable conductivity of artificial fractures, a novel well testing model for fractured horizontal well in tight gas reservoirs is proposed. And the semianalytical solution of this new model is obtained by dividing the artificial fracture into different segments under the integrative methods of Laplace transformation, point source function, perturbation theory, superposition principle, and Stehfest numerical inversion. After validation, the semianalytical solution is consistent with that of Zerzar’s model (2004). Also, typical pressure and pressure derivative curves are plotted. According to typical curves, seven regimes can be derived, namely, bilinear flow, linear flow, early-time pseudoradial flow, biradial flow, intermediate-time pseudoradial flow, and pseudo-steady state interporosity flow, and late-time pseudoradial flow can be identified. In addition, this paper analyzes the impact on pressure and pressure derivative curves exerted by variable conductivity and stress-sensibility. The results show that variable conductivity mainly affects the early flow regimes, including bilinear flow, linear flow, and early-time radial flow, while the stress-sensitivity mainly affects the later flow regimes, including intermediate-time pseudoradial flow, pseudo-steady state interporosity flow, and late-time pseudoradial flow. The typical curves will ascend with the increasing of stress-sensitivity coefficient. The research provides a method for precise prediction of formation parameters and has a significant impact on the tight gas reservoir development

Responses of soil respiration to rainfall depth and frequency in semiarid grassland communities

Climate change is increasing the extreme precipitation depth and frequency, which may cause a strong response of ecological processes in drought regions. To investigate how rainfall depth and frequency alter soil respiration (SR), a rainfall simulation experiment was conducted in grassland communities dominated by Artemisia gmelinii and Lespedeza davurica in Loess Plateau of China. SR rate (Rs), soil temperature (Ts) and soil volumetric water content (Sv) were monitored before and after the rainfall treatments, that is, four depths (5, 10, 20 and 40 mm) and three frequencies (40 mm × 1, 20 mm × 2 and 10 mm × 4) during the growing season (June to September). Results indicated that the response magnitude of Rs increased with rainfall depths, reaching the maximum under 40 mm, and the increments were tightly related to rainfall frequency and community type. The increase and mean value of Rs in A. gmelinii community were significantly higher than those in L. davurica and bare land under same rainfall depth. L. davurica community was more sensitive to rainfall lower than 10 mm, whereas it had weaker but longer response under rainfall larger than 10 mm compared with A. gmelinii community. Successive rainfall events dampened the pulse effect of Rs but generated more cumulative CO2 emission in vegetation communities. Ts and Sv varied significantly with rainfall depth and co-regulated SR. These findings implied more CO2 will be released from soil in the semiarid grasslands under extreme and successive rainfalls and emphasized the importance of species impact on SR for soil carbon evaluation under future rainfall regimes. © 2021 John Wiley & Sons, Ltd.National Key Research and Development Program of China12 month embargo; first published: 06 July 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]