Hydrogeochemical Processes and Inverse Modeling for a Multilayer Aquifer System in the Yuaner Coal Mine,Huaibei Coalfield,China

Coal mining can dramatically change hydrogeological conditions and induce serious environmental problems. Fifty groundwater samples were collected from the main aquifers in the Yuaner coal mine (Anhui Province, China). The results show that the main hydrogeochemical processes in the mine include dissolution, precipitation, pyrite oxidation, desulfurization, and cation exchange. The Neogene porous aquifer is affected by groundwater flow conditions; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, and cation exchange. The Permian coal measure’s fractured sandstone aquifer was confirmed to be controlled by the region’s geological structure; its main hydrogeochemical processes are desulfurization and cation exchange. The Carboniferous Taiyuan limestone aquifer was determined by both groundwater flow conditions and regional geological structure; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, pyrite oxidation, and cation exchange. Additionally, hydrogeochemical inverse modeling of the groundwater flow path confirm the hydrochemistry results and principal component analysis.

     

Physiochemical structure of semicoke derived from co-carbonization of coal and sawdust blends

The substitution of coal blending with sawdust had been widely investigated for metallurgical coke production. In this paper, the physiochemical structures of the semicoke derived from sawdust/coals blends co-coking were characterized by several analytical techniques including FTIR-ATR, XPS, NMR, OM, and SEM. Meanwhile, the influence of the sawdust on the physicochemical properties of the sawdust/coals blends were also investigated. Results indicated that partial substitution of coal blending with sawdust benefited from the formation of colloid and optical anisotropy due to the positive synergetic effect, whereas high proportion of sawdust (>10 wt%) inhibited the agglomeration of semi-coke. On the other hand, the semicoke consisted primarily of aromatic carbons replaced by the oxygen linked to carbons and aliphatic carbons when the coal blending was replaced by high proportion of sawdust, causing a less polyaromatic graphite-like structure formation in the semicoke.     

A Feature Extraction Method for scRNA-seq Processing and Its Application on COVID-19 Data Analysis

Single-cell RNA-sequencing (scRNA-seq) is a rapidly increasing research area in biomedical signal processing. However, the high complexity of single-cell data makes efficient and accurate analysis difficult. To improve the performance of single-cell RNA data processing, two single-cell features calculation method and corresponding dual-input neural network structures are proposed. In this feature extraction and fusion scheme, the features at the cluster level are extracted by hierarchical clustering and differential gene analysis, and the features at the cell level are extracted by the calculation of gene frequency and cross cell frequency. Our experiments on COVID-19 data demonstrate that the combined use of these two feature achieves great results and high robustness for classification tasks.     

Atomistic insight into the lubrication of glycerol aqueous solution: The role of the solid interface-induced microstructure of fluid molecules

Molecular dynamics simulations are performed to investigate the solid surface-induced microstructure and friction coefficient of glycerol aqueous solutions with different water contents confined in graphene and FeO nanoslits. Results show that the friction coefficient of glycerol aqueous solutions confined in both nanoslits presents similar nonlinear variation tendencies with increasing water content, but their lowest value and the corresponding water contents differ. Distinctive microstructures of the near-surface liquid layer induced by surfaces with different hydrophilicity are responsible for their difference in lubrication. The sliding primarily occurs at the solid–liquid interface for the hydrophobic graphene nanoslit owing to almost the same velocity difference in fluid molecules. By contrast, the sliding mainly occurs at the liquid–liquid interface for the hydrophilic FeO nanoslit because of the large velocity difference in fluid molecules. The weaker the interaction force at the sliding position, the lower the friction coefficient.     

Facial-sketch Synthesis: A New Challenge

Machine Intelligence Research - This paper aims to conduct a comprehensive study on facial-sketch synthesis (FSS). However, due to the high cost of obtaining hand-drawn sketch datasets, there is a...     

一种改进启发式算法在解决组合优化问题中的应用

启发式算法是解决组合优化问题的良策,介绍了一种改进的启发式算法和该算法在解决组合优化相关问题上的应用,分析该算法的详细流程,并通过仿真实验验证该算法的性能,并对其优势和不足进行了分析。     

Ferroelectric and electromechanical performance of diverse engineered states of Mn-doped 0.75Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 ceramics

The materials processing history has a great influence on their properties and finally determines their application effect. In this paper, the ferroelectric, polarization-switching current, and strain properties of Mn-doped 0.75Pb(Mg_1/3Nb_2/3)O₃-0.25PbTiO₃ ceramics were studied in fresh state, aged state, and poled state, respectively. Compared with the symmetric polarization-electric-field (P-E) hysteresis loops, current-density-electric-field (J-E) curves, and bipolar electric-field-induced strain (S-E) curves in fresh state samples, asymmetric P-E loops, J-E curves, and bipolar S-E curves were obtained in poled state samples. Well-aged-state samples exhibit double hysteresis P-E loop, four peaks J-E curves, and symmetric S-E curves without negative strain. The symmetry-conforming short-range order (SC-SRO) principle of point defects and internal electric field E_i is employed to clarify the different phenomenon of three states. Results indicated that randomly oriented defect polarization P_D in aged samples can reverse the spontaneous polarization P_S back and result in the double hysteresis P-E loop and four peaks J-E curves. The oriented P_D and resulting E_i in poled-state samples will lead to the asymmetric loops and strain memory effect.     

Inhibiting effect of heterogeneous cations aggregation enhanced by oxygen deficiency on glass formation of BaTi2O5 melts

Although remarkable development of titanate-based glasses has been achieved, challenge remains to elucidate the correlation between structure and glass-forming properties in these systems due to their complex structure that is inconsistent with the classic Zachariasen's model. In this work, we aim to correlate the structural evolution of titanate melts to their glass-forming ability (GFA). The prototypical material barium dititanate (BaTi₂O₅, BT2) melts with different GFA were rendered by controlled melting atmospheres, and the corresponding structural changes were determined using in situ high-energy synchrotron X-ray diffraction combined with empirical potential structure refinement and ab initio molecular dynamics. The results show that BT2 melt in reducing atmosphere shows poor GFA but that in oxidizing atmosphere presents good GFA. Structural analysis demonstrates the mean coordination number of [TiO_m] polyhedra is analogous in the melt under two different atmospheres but an enhanced heterogeneous cations aggregation takes place in the melt under reducing atmosphere, which is closely related to oxygen-deficiencies. Furthermore, we reveal that the enhanced heterogeneous cations aggregation promotes crystallization (and therefore hinders glass formation) through disordering the distribution of [TiO_m] and [BaO_n] polyhedra, changing the connectivity between these polyhedra, creating more crystal-like Ti-Ti clusters, and decreasing topological disorder of BT2 melt. Our work provides a new viewpoint to understand the GFA of titanates melt from structural heterogeneity beyond the previous perspectives that only focus on [TiO_m] polyhedra.     

Zinc doped Fe2O3 for boosting Electrocatalytic Nitrogen Fixation to ammonia under mild conditions

Artificial nitrogen fixation is emerging as a promising approach for synthesis of ammonia at mild conditions. Inspired by biological nitrogen fixation based on bacteria containing iron, zinc doped Fe₂O₃ nanoparticles are proposed as an efficient and earth abundant electrocatalyst for converting N₂ to NH₃. In neutral media, it achieves a maximum Faradaic efficiency (FE) of 10.4% and a large NH₃ yield rate of 15.1 μg h^?1 mg^?1_cat. at ?0.5 V vs. reversible hydrogen electrode. This catalyst also exhibits excellent selectivity and stability. Theoretical calculations suggest the reaction follows the associative enzymatic mechanism and it has a barrier of as low as 0.68 eV.