Modeling and simulation on spontaneous detonation of ammonium nitrate explosive induced by sulfide ores.

In this work, the characteristics of the exothermic reaction between ammonium nitrate and sulfide ores were explored using COMSOL Multiphysics. This reaction can cause an increase in temperature within the blast holes of sulfide mines and can potentially induce premature explosions of the explosives. Initially, simulations were conducted to observe temperature variations in blast holes before and after the loading of explosives. Then, the impact of blast hole diameter and initial temperature on the thermal environment was assessed. Subsequent analysis focused on the fluid field's dynamics, examining flow rate changes and the concentration of signature gases produced by the reaction. Additionally, the influence of blast hole diameter on these parameters was evaluated. The results show that the blast hole temperature is positively related to its diameter and initial temperature. When the diameter of the blast hole is 120 mm and 165 mm, a significant change in flow rate is observed, with a trend of being rapidly increased and then rapidly decreased. The production of NH3 is always found to be greater than that of the other two gases. As for NO and SO2, their production is characterized by an approximate ratio of 1:2. The numerical simulation results can provide important theoretical guidance for the spontaneous detonation of blast hole in sulfide mines.

Single-cell multi-omics analysis of lineage development and spatial organization in the human fetal cerebellum.

Human cerebellum encompasses numerous neurons, exhibiting a distinct developmental paradigm from cerebrum. Here we conducted scRNA-seq, scATAC-seq and spatial transcriptomic analyses of fetal samples from gestational week (GW) 13 to 18 to explore the emergence of cellular diversity and developmental programs in the developing human cerebellum. We identified transitory granule cell progenitors that are conserved across species. Special patterns in both granule cells and Purkinje cells were dissected multidimensionally. Species-specific gene expression patterns of cerebellar lobes were characterized and we found that PARM1 exhibited inconsistent distribution in human and mouse granule cells. A novel cluster of potential neuroepithelium at the rhombic lip was identified. We also resolved various subtypes of Purkinje cells and unipolar brush cells and revealed gene regulatory networks controlling their diversification. Therefore, our study offers a valuable multi-omics landscape of human fetal cerebellum and advances our understanding of development and spatial organization of human cerebellum.

Mapping the knowledge domain of microbial desulfurization application in fuels and ores for sustainable industry.

Direct application of high-sulfur fuels and ores can cause environmental pollution (such as air pollution and acid rain) and, in serious cases, endanger human health and contribute to property damage. In the background of preserving the environment, microbial desulfurization technologies for high-sulfur fuels and ores are rapidly developed. This paper aims to reveal the progress of microbial desulfurization research on fuels and ores using bibliometric analysis. 910 publications on microbial desulfurization of fuels and ores from web core databases were collected in this work, spanning 39 years. Through 910 retrieved documents, collaborative networks of authors, institutions and countries were mapped by this work, the sources of highly cited articles and cited documents were statistically analyzed, and keyword development from different perspectives was discussed. The results of the study provide a reference for microbial desulfurization research and benefit environmental protection and energy green applications.

Modeling Corrosion Product Film Formation and Hydrogen Diffusion at the Crack Tip of Austenitic Stainless Steel.

Corrosion product films (CPFs) have significant effects on hydrogen permeation and the corrosion process at the crack tip. This paper established a two-dimensional calculation model to simulate the formation of CPFs at the crack tip and its effects on the crack tip stress status and hydrogen diffusion. The CPFs were simplified as a single-layer structure composed of Fe2O3, the effective CPFs boundary was modeled by the diffusion of oxygen, and the CPF-induced stress was modeled by hygroscopic expansion. The simulation was conducted with two stages; the first stage was to simulate the formation of CPFs formation and its effects on the crack tip stress status, while the second stage focused on the hydrogen diffusion with and without CPF formation under different external tensile loads. The results indicate that the highest compressive stress induced by the formation of CPFs is located at 50~60° of the crack contour and dramatically weakens the crack tip tensile stress at low-stress status. The CPFs can inhibit the hydrogen permeation into the crack tip, and the hydrostatic pressure effects on the redistribution of the permeated hydrogen are significant under larger external load conditions.

Effect of Mn Deficiency on Carbon and Nitrogen Metabolism of Different Genotypes Seedlings in Maize (Zea mays L.).

Manganese deficiency critically impairs the function and stability of photosystem II (PSII) and negatively impacts crop growth and yield. However, the response mechanisms of carbon and nitrogen metabolism to Mn deficiency in different genotypes of maize and the differences in Mn deficiency tolerance are unclear. Herein, three different genotypes of maize seedlings (sensitive genotype: Mo17, tolerant genotype: B73, and B73 × Mo17) were exposed to Mn deficiency treatment for 16 days using liquid culture with different concentrations of MnSO4 [0.00, 2.23, 11.65, and 22.30 mg/L (control)]. We found that complete Mn deficiency significantly reduced maize seedling biomass; negatively affected the photosynthetic and chlorophyll fluorescence parameters; and depressed nitrate reductase, glutamine synthetase, and glutamate synthase activity. This resulted in reduced leaf and root nitrogen uptake, with Mo17 being most severely inhibited. B73 and B73 × Mo17 maintained higher sucrose phosphate synthase and sucrose synthase activities and lower neutral convertase activity compared to Mo17, which resulted in higher accumulation of soluble sugars and sucrose and maintenance of the osmoregulation capacity of leaves, which helped mitigate damage caused by Mn deficiency. The findings revealed the physiological regulation mechanism of carbon and nitrogen metabolism in different genotypes of maize seedlings that resist Mn deficiency stress, providing a theoretical basis for developing high yield and quality.

Architecting fire safe hierarchical polymer nanocomposite films with excellent electromagnetic interference shielding via interface engineering.

Integrating high flame retardancy and excellent electromagnetic interference (EMI) shielding into polymetric materials is extremely necessary, and well dispersing conductive fillers into polymeric materials is still a great challenge because of incompatible interfacial polarity between polymer matrix and conductive fillers. Therefore, under the premise of maintaining integral conductive films in the process of hot compression, constructing a novel EMI shielding polymer nanocomposites where conductive films closely adhere to polymer nanocmposites layers should be a fascinating stratety. In this work, salicylaldehyde-modified chitosan decorated titanium carbide nanohybrid (Ti3C2Tx-SCS) was combined with piperazine-modified ammonium polyphosphate (PA-APP) to fabricate thermoplastic polyurethane (TPU) nanocomposites, which were used for construction of hierarchical nanocomposite films by inserting reduced graphene oxide (rGO) films into TPU/PA-APP/Ti3C2Tx-SCS nanocomposite layers through our self-developed air assisted hot pressing technique. The total heat release, total smoke release and total carbon monoxide yield for TPU nanocomposite containing 4.0 wt% Ti3C2Tx-SCS nanohybrid were 58.0%, 58.4% and 75.8% lower than those of pristine TPU, respectively. Besides, the hierarchical TPU nanocomposite film containing 1.0 wt% Ti3C2Tx-SCS presented an averaged EMI shielding effectiveness of 21.3 dB in X band. This work provides a promising strategy for fabricating fire safe and EMI shielding polymer nanocomposites.

Mapping knowledge domains for mine heat hazard: a bibliometric analysis of research trends and future needs.

As the shallow mineral resources are nearly depleted, the mining of deep resources has become an urgent problem to be studied. The increase in mine depth can lead to the increase of mine heat hazard, which is a critical concern for mining safety/occupational health and safety. However, there are limited review articles available regarding the prevention of mine heat hazard. To fill in this gap, a bibliometric analysis and knowledge mapping of the field of mine heat hazard prevention are presented in this paper. A total of 314 papers from the Web of Science (WOS) core collection database that published between January 1998 and July 2022 were analyzed using VOSviewer and CiteSpace. China, South Africa, Poland, USA, and Australia are the top five countries in this field. The important journals are Applied Thermal Engineering, Applied Energy, Energies, and International Journal of Mining Science and Technology. In addition, the research focal points and two research fronts were identified and discussed. The knowledge base of mine heat hazard research focuses on mine cooling technology, energy efficiency optimization of cooling systems, thermodynamic theory, and occupational health. There are two research fronts. One is to use the numerical simulation method to study various problems such as simulate the performance of refrigeration systems and thermal comfort in mines. The second is to study the occupational health impact of climate change on miners. Therefore, this paper provides readers and academics with an overview of the intellectual structure and knowledge body that have been developed on the subject of mine heat hazard.

Couplet Analysis of Linguistic Topology Using Deep Neural Networks in Cognitive Linguistics.

The work reported here primarily aims to realize the automatic generation of couplets using the linguistic topology of deep neural network (DNN). First, the symmetry, topology, and cognitive linguistics of language are explored to lay a theoretical foundation for subsequent model establishment and analysis. Then, the recurrent neural network (RNN) is employed to build the Seq2Seq model, and Liweng's Guide to Rhyme (an ancient Chinese enlightenment reading material to poetry creation) is imported into the Seq2Seq model as a basic corpus. Eventually, the entire system is implemented automatically on TensorFlow. The system undergoes tests of the five-character quatrain, the seven-character quatrain, the couplet, and the part-of-speech detection. Results demonstrate that both the first and the second lines of the couplet present an excellent correspondence regarding sentences and words. After some famous verses are entered, the second line of the couplet obtained is quite vivid and appropriate. Meanwhile, the results can be generated quickly and meet the requirements on rhyme and couplet matching. This model can input verses according to users' own needs and generate the second line of the couplet quickly, showing good correspondence in words, part-of-speech, and sentence pattern. Because the couplet belongs to Chinese traditional culture, it has a strong local Chinese cultural flavor. The system designed based on computer technology can help people learn and experience the charm of couplets.

A CAST-Based Analysis of the Metro Accident That Was Triggered by the Zhengzhou Heavy Rainstorm Disaster.

Emergency management research is used to deal with the increasing number of extreme weather threats in urban areas. This paper uses causal analysis based on systems theory (CAST) to review the subway water ingress accident and the government's emergency management actions in Zhengzhou, Henan Province, during the heavy rainstorm disaster on 20 July 2021. The aims of this article are to establish safety control structures at both the enterprise level and the government level, and to systematically analyze the problems in emergency management in Zhengzhou City. Our analysis found that the construction of disaster prevention facilities restricted emergency management. Therefore, we suggest that enterprises and governments not only pay attention to emergency management, but also to the construction of disaster prevention facilities. This article also points out that the system of chief executive responsibility that is implemented in China is becoming a double-edged sword in emergency management. Our study makes recommendations for enhancing the capacities of emergency management, points out the shortcomings of the existing emergency management structure, and provides knowledge gained for future emergency management research.

Analysis and Visualization of Research on Resilient Cities and Communities Based on VOSviewer.

To objectively grasp the current situation and development trend of resilient cities or communities (RC) research. The articles in Web of Science (WOS) Core Collection databases from 1995 to 2022 were used as a sample, and bibliometrics was used to statistically analyze the year of publication and number of articles, highly cited documents and keyword hotness in this field. VOSviewer was used to explore the knowledge graph of RC research documents. The results show that: the development process is roughly divided into 3 periods: no attention (1995-2004), starting (2005-2014), and rapid growth (2015-2021). The journal "Sustainability" and "International journal of disaster risk reduction" are the key journals publishing RC research. Serre and Shaw are the most productive authors. The USA is still the leading country in this field of RC. Colorado State Univ, Texas a&m Univ, and Delft Univ Technol are the main research institutions. The keyword analysis indicates the hot topics in different periods. Moreover, several limitations and some recommendations for future research on RC are also given based on this.

Aerial-aquatic robots capable of crossing the air-water boundary and hitchhiking on surfaces.

Many real-world applications for robots-such as long-term aerial and underwater observation, cross-medium operations, and marine life surveys-require robots with the ability to move between the air-water boundary. Here, we describe an aerial-aquatic hitchhiking robot that is self-contained for flying, swimming, and attaching to surfaces in both air and water and that can seamlessly move between the two. We describe this robot's redundant, hydrostatically enhanced hitchhiking device, inspired by the morphology of a remora (Echeneis naucrates) disc, which works in both air and water. As with the biological remora disc, this device has separate lamellar compartments for redundant sealing, which enables the robot to achieve adhesion and hitchhike with only partial disc attachment. The self-contained, rotor-based aerial-aquatic robot, which has passively morphing propellers that unfold in the air and fold underwater, can cross the air-water boundary in 0.35 second. The robot can perform rapid attachment and detachment on challenging surfaces both in air and under water, including curved, rough, incomplete, and biofouling surfaces, and achieve long-duration adhesion with minimal oscillation. We also show that the robot can attach to and hitchhike on moving surfaces. In field tests, we show that the robot can record video in both media and move objects across the air/water boundary in a mountain stream and the ocean. We envision that this study can pave the way for future robots with autonomous biological detection, monitoring, and tracking capabilities in a wide variety of aerial-aquatic environments.

Methyl-CpG binding protein 2 is associated with the prognosis and mortality of elderly patients with hip fractures.

OBJECTIVES: To investigate the expression level and clinical significance of Methyl-CpG binding Protein 2 (MECP2) in elderly patients with hip fractures. METHODS: This prospective observational study included 367 elderly patients with hip fractures between April 2016 and December 2018. All the patients were treated with internal fixation or joint replacement. In addition, 50 healthy elderly individuals were enrolled as healthy controls. The serum levels of MECP2 and inflammatory factors Interleukin (IL)-1ß, IL-6, IL-8, and Tumor Necrosis Factor (TNF)-α was determined by enzyme-linked immunosorbent assay. Data on patients' basic characteristics and postoperative complications were collected. The Harris score was used to assess hip function at 1-month, 3-months, and 6-months after surgery. Patient quality of life was measured using the Barthel Index (BI) score 3-months after surgery. The 1-year mortality was analyzed using the Kaplan-Meier curve, and logical regression was used to analyze the risk factors for mortality. RESULTS: No significant differences were observed in the basic clinical characteristics of all patients. The serum MECP2 levels were remarkably high in patients with hip fractures and negatively correlated with serum IL-1ß, IL-6, and TNF-α levels. Patients with higher MECP2 predicted higher dynamic Harris scores, lower postoperative complications, lower 1-year mortality, and higher BI scores. Logical regression showed that age was the only independent risk factor for postoperative 1-year mortality in elderly patients with hip fractures. CONCLUSION: Lower MECP2 predicted poor prognosis and higher 1-year mortality in elderly patients with hip fractures.

Evolutionarily conservative and non-conservative regulatory networks during primate interneuron development revealed by single-cell RNA and ATAC sequencing.

The differences in size and function between primate and rodent brains, and the association of disturbed excitatory/inhibitory balance with many neurodevelopmental disorders highlight the importance to study primate ganglionic eminences (GEs) development. Here we used single-cell RNA and ATAC sequencing to characterize the emergence of cell diversity in monkey and human GEs where most striatal and cortical interneurons are generated. We identified regional and temporal diversity among progenitor cells which give rise to a variety of interneurons. These cells are specified within the primate GEs by well conserved gene regulatory networks, similar to those identified in mice. However, we detected, in human, several novel regulatory pathways or factors involved in the specification and migration of interneurons. Importantly, comparison of progenitors between our human and published mouse GE datasets led to the discovery and confirmation of outer radial glial cells in GEs in human cortex. Our findings reveal both evolutionarily conservative and nonconservative regulatory networks in primate GEs, which may contribute to their larger brain sizes and more complex neural networks compared with mouse.

An Investigation of a New Parameter Based on the Plastic Strain Gradient to Characterize Composite Constraint around the Crack Front at a Low Temperature.

Stress corrosion cracking (SCC) is an important destruction form of materials such as stainless steel, nickel-based alloy and their welded components in nuclear reactor pressure vessels and pipes. The existing popular quantitative prediction models of SCC crack growth rate are mainly influenced by fracture toughness values KJc or Jc. In particular, the composite constraint, containing the in-plane constraints and out-of-plane constraints around the crack front, has a significant influence on the fracture toughness of structures in nuclear power plants. Since the plastic strain gradient is a characterization parameter of the quantitative prediction model for crack growth rate, it may be a characterization parameter of composite constraint. On the basis of the experimental data at a low temperature of alloy steel 22NiMoCr3-7 used in nuclear pressure vessels, the gradient of equivalent plastic strain DPEEQ around the crack fronts at different constraint levels was calculated using the finite element method, which introduces a new non-dimensional constraint parameter Dp, to uniformly characterize the in-plane and out-of-plane constraint effects. Compared with constraint parameters APEEQ or Ap, the process of obtaining parameters DPEEQ or Dp is much simpler and easier. In a wide range, a single correlation curve was drawn between parameter Dp and normalized fracture toughness values KJc/Kref or Jc/Jref of specimens at a low or high constraint level. Therefore, regardless of whether the constraint levels of the structures or standard specimens are low or high, constraint parameter Dp can be used to measure their fracture toughness. To build an evaluation method that has structural integrity and safety while containing the composite constraint effects, in addition to accurate theoretical interpretation, further verification experiments, numerical simulations and detailed discussions are still needed.

Modeling the Hydrogen Redistribution at the Grain Boundary of Misoriented Bicrystals in Austenite Stainless Steel.

Hydrogen embrittlement, as one of the major concerns for austenitic stainless steel, is closely linked to the diffusion of hydrogen through the grain boundary of materials. The phenomenon is still not well understood yet, especially the full interaction between hydrogen diffusion and the misorientation of the grains. This work aimed at the development of a robust numerical strategy to model the full coupling of the hydrogen diffusion and the anisotropic behavior of crystals in 316 stainless steel. A constitutive model, which allows easy incorporation of crystal orientation, various loading conditions, and arbitrary model geometries, was established by using the finite element package ABAQUS. The study focuses on three different bicrystal models composed of misoriented crystals, and the results indicate that the redistribution of hydrogen is significant closely to the grain boundary, and the redistribution is driven by the hydrostatic pressure caused by the misorientation of two neighboring grains. A higher elastic modulus ratio along the tensile direction will lead to a higher hydrogen concentration difference in the two grains equidistant from the grain boundary. The hydrogen concentration shows a high value in the crystal along the direction with stiff elastic modulus. Moreover, there exists a large hydrogen concentration gradient in a narrow region very close to the grain boundary to balance the concentration difference of the neighboring grains.

Characterization and bioassays of extracellular vesicles extracted by tangential flow filtration.

Aim: To evaluate the efficiency of tangential flow filtration (TFF) in improving the yield of human umbilical cord mesenchymal stem cell (hucMSC)-derived extracellular vesicles (EVs) while promoting cell regeneration under oxidative stress. Methods: HucMSC-EVs were extracted from supernatants by ultracentrifugation (UC-EVs) and TFF (TFF-EVs), followed by feature characterization and bioactivity assays. Results: The yield of TFF-EVs increased 18-times compared with that of UC-EVs. TFF-EVs displayed proliferation-promoting ability similar to that of UC-EVs in the damaged HaCaT cell model with ultraviolet radiation B (UVB) and H2O2. Furthermore, the antiapoptotic effects of TFF-EVs were improved, whereby the apoptosis rate exhibited a 3.7-fold decrease. Conclusion: HucMSC-EVs extracted by TFF show a higher yield and rejuvenate the damaged HaCaT cells induced by oxidative stress.

Plain language summary The progresses in regenerative medicine will enable a perfect repair of burns. Stem cells release extracellular vesicles around injured tissues to improve its structural and functional repair. But the current methods for vesicles enrichment are not efficient enough to meet the needs of investigation. Here we isolated the vesicles from the stem cells supernatants by either traditional method or ultrafiltration. We found that the vesicles isolated with ultrafiltration method displayed a similar cell proliferation ability of that with the traditional one. The output of the vesicles or its anti-aging capability has increased 18- or 3.7-times respectively. Therefore, the scalable and effective isolation method described here may facilitate the successful medical translation of the vesicles for clinical use.

Constructing segregated polystyrene composites for excellent fire resistance and electromagnetic wave shielding.

Electroconductive polystyrene (PS) composites with ideal flame-retardant properties are considered as potential electromagnetic interference (EMI) shielding materials. In this work, PS/silicon wrapped ammonium polyphosphate/multi-wall carbon nanotubes (PS/SiAPP/MWCNT) composites with segregated structure were synthesized via the methods of balling mill and hot-pressing. The obtained results revealed that the SiAPP and MWCNT were successfully introduced onto PS spheres and showed uniform distribution on the PS surface. The thermogravimetric analysis showed that PS/SiAPP/MWCNT containing 7 wt% MWCNT exhibited excellent thermal stability. Furthermore, the results of cone calorimeter test indicated that the heat release rate and total heat release of the PS/SiAPP/MWCNT containing a loading of 7 wt% MWCNT were reduced by 60.5% and 33.9%, respectively. In addition, the EMI shielding performance could reach 11 dB. Above results implied that the synergistic effect between the MWCNT and SiAPP effectively enhanced the flame retardant performance of the PS by promoting the generation of dense and continuous char layer to protect the PS from burning. The multiple reflection and adsorption are responsible for improved EMI shielding effectiveness. Therefore, segregated PS/SiAPP/MWCNT hybrid is an up-and-coming candidate for satisfactory EMI shielding materials with exceptional fire retardancy for electronic devices.

Lightweight, amphipathic and fire-resistant prGO/MXene spherical beads for rapid elimination of hazardous chemicals.

Frequent leaks of hazardous chemicals have a huge impact on human lives, property and the ecological environment. Therefore, the three-dimensional functional porous materials with high absorption efficiency and special wettability for the disposal of hazardous chemical spills is an urgent demand. In this work, a series of spherical beads consisting of partially reduced graphene oxide (prGO) and MXene (Ti3C2Tx) nanosheets were constructed by hydrogen bond induced self-assembly along with freeze-drying and thermal treatment. The lightweight and amphipathic prGO/MXene spherical beads (prGMSBDs) had millimeter-level size, spherical morphology and highly porous internal structure, which were especially suitable for eliminating hazardous chemicals. Because of their excellent thermal stability and fire retardance, the prGMSBDs could be used to absorb flammable organic liquids, reducing the fire risk of the flammable hazardous chemical spills. Indeed, the prGMSBDs exhibited outstanding absorption performances for various hazardous chemicals, including organic solvents and water-based concentrated acid and alkali. Moreover, the prGMSBDs showed relatively stable absorption performance after five absorption-drying cycles. Due to meeting the requirements of both amphipathic characteristic and flame retardancy, the prGMSBDs reported in this work may offer a promising strategy for rapidly cleaning up various hazardous chemicals and open a feasible route to protecting the combustible hazardous chemical spills from fire.

Methyl-CpG binding protein 2 is associated with the prognosis and mortality of elderly patients with hip fractures

ABSTRACT Objectives To investigate the expression level and clinical significance of Methyl-CpG binding Protein 2 (MECP2) in elderly patients with hip fractures. Methods This prospective observational study included 367 elderly patients with hip fractures between April 2016 and December 2018. All the patients were treated with internal fixation or joint replacement. In addition, 50 healthy elderly individuals were enrolled as healthy controls. The serum levels of MECP2 and inflammatory factors Interleukin (IL)-1β, IL-6, IL-8, and Tumor Necrosis Factor (TNF)-α was determined by enzyme-linked immunosorbent assay. Data on patients' basic characteristics and postoperative complications were collected. The Harris score was used to assess hip function at 1-month, 3-months, and 6-months after surgery. Patient quality of life was measured using the Barthel Index (BI) score 3-months after surgery. The 1-year mortality was analyzed using the Kaplan-Meier curve, and logical regression was used to analyze the risk factors for mortality. Results No significant differences were observed in the basic clinical characteristics of all patients. The serum MECP2 levels were remarkably high in patients with hip fractures and negatively correlated with serum IL-1β, IL-6, and TNF-α levels. Patients with higher MECP2 predicted higher dynamic Harris scores, lower postoperative complications, lower 1-year mortality, and higher BI scores. Logical regression showed that age was the only independent risk factor for postoperative 1-year mortality in elderly patients with hip fractures. Conclusion Lower MECP2 predicted poor prognosis and higher 1-year mortality in elderly patients with hip fractures.