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After landing in the Utopia Planitia, Tianwen-1 formed the deepest landing crater on Mars, approximately 40 cm deep, exposing precious information about the mechanical properties of Martian soil. We established numerical models for the plume-surface interaction (PSI) and the crater formation based on Computational Fluid Dynamics (CFD) methods and the erosion model modified from Roberts’ Theory. Comparative studies of cases were conducted with different nozzle heights and soil mechanical properties. The increase in cohesion and internal friction angle leads to a decrease in erosion rate and maximum crater depth, with the cohesion having a greater impact. The influence of the nozzle height is not clear, as it interacts with the position of the Shock Diamond to jointly control the erosion process. Furthermore, we categorized the evolution of landing craters into the dispersive and the concentrated erosion modes based on the morphological characteristics. Finally, we estimated the upper limits of the Martian soil’s mechanical properties near Tianwen-1 landing site, with the cohesion ranging from 2612 to 2042 Pa and internal friction angle from 25° to 41°.

The ionicity of ionic solids is typically characterized by the electronegativity of the constituent ions. Electronegativity measures the ability of electron transfer between atoms and is commonly considered under ambient conditions. However, external stresses profoundly change the ionicity, and compressed ionic compounds may behave differently. Here, we focus on silver halides, with constituent ions from one of the most electropositive metals and some of the most electronegative nonmetals. Using first-principles calculations, we find that the strengths of the ionic bonds in these compounds change greatly under pressure owing to downshifting of the Ag 4d-orbital. The center of this orbital is lowered to fill the antibonding state below the Fermi level, leading to chemical decomposition. Our results suggest that under pressure, the orbital energies and correspondingly the electronegativities still tune the ionicity and control the electron transfer, ionicity, and reactivity of both the metal and the nonmetal elements. However, the effects of orbital energies start to become dominant under pressure, causing substantial changes to the chemistry of ionic compounds and leading to an unusual phenomenon in which elements with substantial electronegativity differences, such as Ag and Br, do not necessarily form ionic compounds, but remain in their elemental forms.

In situ conversion presents a viable strategy for exploiting low to moderate maturity shale oil. Traditional methods, however, require dense well patterns and substantial energy, which are major hurdles. This study introduces a novel approach employing low-frequency electrical heating via production wells to enhance heat transfer without necessitating additional heating wells. Utilizing a self-developed simulator, we developed a numerical model to evaluate the efficacy of this method in augmenting reservoir temperature and facilitating substance decomposition. Findings indicate that low-frequency electrical heating significantly elevates reservoir temperatures, accelerates hydrocarbon cracking, and boosts fluid production. A sensitivity analysis on various heating strategies and reservoir characteristics showed that elevated heating power can further pyrolyze the heavy oil in the product to light oil, while higher porosity formations favor increased oil and gas output. The study also explores the effect of thermal conductivity on heating efficiency, suggesting that while better conductivity improves heat distribution, it may increase the proportion of heavy oils in the output. Overall, this investigation offers a theoretical foundation for refining in situ conversion technologies in shale oil extraction, enhancing both energy efficiency and production quality.

Block-in-matrix-soils (bimsoils) are geological mixtures that have distinct structures consisting of relatively strong rock blocks and weak matrix soils. It is still a challenge to evaluate the mechanical behaviors of bimsoils because of the heterogeneity, chaotic structure, and lithological variability. As a result, only very limited laboratory studies have been reported on the evolution of their internal deformation. In this study, the deformation evolution of bimsoils under uniaxial loading is investigated using real-time X-ray computed tomography (CT) and image correlation algorithm (with a rock block percentage (RBP) of 40%). Three parameters, i.e. heterogeneity coefficient (K), correlation coefficient (CC), and standard deviation (STD) of displacement fields, are proposed to quantify the heterogeneity of the motion of the rock blocks and the progressive deformation of the bimsoils. Experimental results show that the rock blocks in bimsoils are prone to forming clusters with increasing loading, and the sliding surface goes around only one side of a cluster. Based on the movement of the rock blocks recorded by STD and CC, the progressive deformation of the bimsoils is quantitatively divided into three stages: initialization of the rotation of rock blocks, formation of rock block clusters, and formation of a shear band by rock blocks with significant rotation. Moreover, the experimental results demonstrate that the meso-motion of rock blocks controls the macroscopic mechanical properties of the samples.

The rock characteristic and size–frequency distribution (SFD) on Mars are important for understanding the geologic and geomorphic history of the surface, for evaluating the trafficability of roving, and for planning the potential infrastructure construction. Tianwen-1, China’s first autonomous Mars exploration mission, formed an excavated depression during touchdown, which has been the deepest depression on the Martian surface so far compared with others. According to the images captured using the Navigation and Terrain Cameras (NaTeCams) onboard the rover, Zhurong, the SFD of rocks is calculated and compared inside the excavated depression, within and out of the blast zone. For the first time, the rock size distribution inside the excavated depression is obtained, exposing the geological features of the shallow subsurface on Mars at a depth of tens of centimeters, which will surely be important for future drilling missions. It is found that the rock abundance in the depression is smaller than the original abundance on the surface, and the distribution of rocks in the blast zone on the surface is greatly influenced by the touchdown. In addition, based on the fractal dimension of rock sizes, the rocks (>10 mm) at the shallow subsurface of the Zhurong landing site may experience two different geological processes.

The plume–surface interaction (PSI) is a common phenomenon that describes the environment surrounding the landers resulting from the impingement of hot rocket exhaust on the regolith of planetary bodies. The PSI will cause obscuration, erosion of the planetary surface, and high-speed spreading of dust or high-energy ejecta streams, which will induce risks to a safe landing and cause damage to payloads on the landers or to nearby assets. Safe landings and the subsequent scientific goals of deep-space exploration in China call for a comprehensive understanding of the PSI process, including the plume flow mechanics, erosion mechanism, and ejecta dynamics. In addition, the landing crater caused by the plume provides a unique and insightful perspective on the understanding of PSI. In particular, the PSI can be used directly to constrain the composition, structure, and mechanical properties of the surface and subsurface soil. In this study, we conducted a systematic review of the phenomenology and terrestrial tests of PSI: we analyzed the critical factors in the PSI process and compared the differences in PSI phenomena between lunar and Martian conditions; we also reviewed the main erosion mechanisms and the evolution and development of terrestrial tests on PSI. We discuss the problems with PSI, challenges of terrestrial tests, and prospects of PSI, and we show the preliminary results obtained from the landing crater caused by the PSI of Tianwen-1. From analysis of the camera images and digital elevation model reconstructions, we concluded that the landing of Tianwen-1 caused the deepest crater (depth > 40 cm) on a planetary surface reported to date and revealed stratigraphic layers in the subsurface of Martian soil. We further constrained the lower bounds of the mechanical properties of Martian soil by a slope stability analysis of the Tianwen-1 landing crater. The PSI may offer promising opportunities to obtain greater insights into planetary science, including the subsurface structure, mineral composition, and properties of soil.

Oil shale, as a vast potential resource, is considered an important alternative energy source, and its effective development and economic utilization are of significant importance in alleviating the contradiction between energy supply and demand. Presently, the in situ conversion technology for oil shale has gained significant global attention, with numerous extraction methods undergoing active research and development. One of these methods is the in situ conversion of oil shale based on the hydration reaction of calcium-oxide-based composite material (CaO-CM). This approach harnesses the heat produced by the reaction between CaO-CM and water as a heat source for the pyrolysis of oil shale. This paper conducted experiments to assess the feasibility of temperature associated with this method. The feasibility study mainly includes two aspects: First, it is necessary to investigate whether the temperature generated by the hydration reaction of CaO-CM can meet the temperature requirements for the pyrolysis of oil shale. Through pyrolysis experiments of Xinjiang oil shale, the minimum temperature required for oil shale pyrolysis was determined to be 330 °C. High-temperature and high-pressure reaction vessels were employed to explore the temperature generated by the hydration reaction of CaO-CM. The results show that with the increase in environment pressure, environment temperature, and reaction mass, the maximum temperature generated by the hydration reaction of CaO-CM also increases (reach 455.5 °C), meeting the temperature requirements for the pyrolysis of oil shale. Second, the study evaluates whether the hydration reaction of CaO-CM can induce pyrolysis hydrocarbons of the oil shale. Through the pyrolysis experiments of oil shale based on the hydration reaction of CaO-CM, the changes in the content of pyrolysis hydrocarbons (S2) in oil shale before and after pyrolysis are measured. The results show that under 10 MPa pressure, the content of pyrolysis hydrocarbons in the oil shale decreased from 40.96 mg/g to 0.08 mg/g after pyrolysis. This confirms the feasibility of the temperature conditions for the in situ conversion of oil shale based on the hydration reaction of CaO-CM.

Many phenolic compounds have been found to have endocrine disrupting activities, but their arylamine analogs, the phenolic hydroxyl groups substituted by aniline amino groups, have rarely been reported. 4,4′-(9-Fluorenylidene)dianiline (BAFL) is an arylamine analog of fluorene-9-bisphenol (BHPF) and BHPF has been reported to be a strong antiestrogen which could cause endometrial atrophy, ovarian damage and adverse pregnancy outcomes in animals. BAFL has been widely used as material to synthetize polymers, such as polyimides, polyamide, and polyamine, for various uses since the 1970s. Here, we assessed the antiestrogenicity of BAFL using a variety of methods and looked into its impacts on the development of females in CD-1 mice. With the aid of a yeast estrogen screen assay, we found BAFL possessed obviously antiestrogenic activity (IC50 = 8.15 × 10−6 M), which close to that of tamoxifen and BHPF. Using a 10-d mouse uterotrophic assay, we found that BAFL obviously decreased uterine weight in a dose-dependent way. Histological analyses of mouse uteri revealed that BAFL induced marked endometrial atrophy and inhibited the uterine development. Immunohistochemical analyses showed that Sprr2d, an estrogen-responsive gene encoding protein, was mainly expressed in endometrial epithelial cells and BAFL decreased the areas and levels of Sprr2d staining in mouse uteri. It was clear from uterine transcriptome investigations that BAFL significantly downregulated the expressions of multiple genes responding to estrogen. Molecular docking showed that BAFL could effectively occupy the antagonist-binding pocket of hERα, and one of the amino groups of BAFL formed hydrogen bonds with the side chains of Arg394 and Glu353 in the receptor. These results indicated that BAFL exhibited clearly antiestrogenic characteristics and could interfere with normal female development in mice, which should be avoided using in commodities that come into direct contact with humans. Moreover, this study indicated that the arylamine analogs of phenolic endocrine disrupting chemicals might also have endocrine disrupting activities.

Identifying chemicals with endocrine disrupting properties linked to disease outcomes is a key concern, as stated in the WHO-UNEP 2012 report on endocrine-disrupting chemicals. The chemical 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (BPEF) is widely and increasingly applied in synthesizing fluorene-based cardo polymers with superior optical, thermal and mechanical properties for various uses. However, little toxicological information is available regarding its safety. Here, we studied the endocrine disrupting property of BPEF by multiple toxicological tools and investigated its effects on female development in adolescent mice. Using the yeast two-hybrid bioassay, BPEF showed strong antiestrogenicity which was similar to that of tamoxifen, an effective antiestrogenic drug. In adolescent CD-1 mice, BPEF significantly decreased the uterine weight at relatively low doses and induced marked endometrial atrophy. Immunohistochemical staining and transcriptome analyses of the mice uteri revealed that BPEF could repressed the expressions of estrogen-responsive genes. Molecular simulation indicated that BPEF could be docked into the antagonist pocket of human estrogen receptor α, and the formation of hydrogen bonds and hydrophobic interactions between BPEF and the active site of receptor maintained their strong binding. All of the data demonstrated that BPEF possessed strong antiestrogenic property and might disrupt female development, suggesting it should be avoided in making products that might directly expose to people, particularly immature women.

In situ heat injection is a suitable technique for extracting shale oil from reservoirs with high organic matter content but insufficient thermal maturation. To optimize the stimulation process and to avoid unnecessary energy consumption, understanding the thermal process and the effects of thermal parameters is crucial. This research employs a self-developed simulator to build a 2D numerical model of the in situ conversion process of kerogen with electric heaters. A benchmark model is first established to determine the effects of heat injection on crude oil production and kerogen decomposition. Subsequently, this study analyzes the evolution of shale oil within the reservoir, identifying the role of thermal and physical properties in crude oil production and kerogen decomposition during the stimulation treatment. A sensitivity analysis of the thermal properties of the reservoir is also carried out, which allows for defining the role of the thermal conductivity of the rock during the stimulation process. Finally, it is observed that, when using the injection at a constant power, the injection time to achieve a suitable large rate of decomposition is shorter than at a constant temperature—consequently, it has a higher economic advantage.

Hydraulic fracturing is one of the most important technologies for shale gas production. Complex hydraulic fracture networks can be stimulated in shale reservoirs due to the existence of numerous natural fractures. The prediction of the complex fracture network remains a difficult and challenging problem. This paper presents a fully coupled hydromechanical model for complex hydraulic fracture network propagation based on the discontinuous deformation analysis (DDA) method. In the proposed model, the fracture propagation and rock mass deformation are simulated under the framework of DDA, and the fluid flow within fractures is simulated using lubrication theory. In particular, the natural fracture network is considered by using the discrete fracture network (DFN) model. The proposed model is widely verified against several analytical and experimental results. All the numerical results show good agreement. Then, this model is applied to field-scale modeling of hydraulic fracturing in naturally fractured shale reservoirs. The simulation results show that the proposed model can capture the evolution process of complex hydraulic fracture networks. This work offers a feasible numerical tool for investigating hydraulic fracturing processes, which may be useful for optimizing the fracturing design of shale gas reservoirs.

Odor ΨΩγemission has become mathvariant="normal" mathvariant="sans-serif-bold-italic" an important issue in kitchen waste management. Ammonia and hydrogen sulfide are the two most important odor sources as they contribute malodor and can cause health problems. As biotreatment and chemical treatment are two majorly applied technologies for odor control, in this study, they were used to remove ammonia and hydrogen sulfide and the performance of each process was compared. It was found that chemical absorption could efficiently eliminate both ammonia and hydrogenmathvariant="script" sulfide, and the removal efficiencies of ammonia and hydrogen sulfide highly depended on the pH of the adsorbent, contacting time, and gas and solution ratio (G/S). The ammonia-removal efficiency reached 100% within less than 2 s at G/S 600 and pH 0.1. The complete removal of hydrogen sulfide was achieved within 2 s at G/S 4000 and pH 13. Biotrickling filter showed better ability for hydrogen sulfide removal and the removal efficiency was 91.9%; however, the ammonia removal was only 73.5%. It suggests that chemical adsorption is more efficient compared to biotreatment for removing ammonia and hydrogen sulfide. In the combination of the two processes, biotrickling filter followed by chemical adsorption, the final concentrations of ammonia and hydrogen sulfide could meet the Level 1 standard of Emission Standards for Odor Pollution (China). The study provides a potential approach for odor control during kitchen waste aerobic composting.

Fluorene-9-bisphenol (BHPF), a substitute for bisphenol A (BPA), has been widely used in the synthesis of polyester polymers. Studies have reported multiple BHPF toxicities but its effect on the liver remains unknown. In this study, we performed short-term and subchronic toxicity tests, as well as primary hepatocyte experiments, to investigate the hepatic toxicity of BHPF using CD-1 mice. And microarray was used to analyze the changes of global gene expression in the liver of mice treated with BHPF. The results showed that the liver coefficient and the activities of serum aminotransferases were obviously elevated by BHPF at doses of 27.8 mg/kg body weight (bw)/day or higher in mice treated for 10 days. Histological analysis showed obvious changes, including narrowed hepatic sinuses, dilated central vein, leucocyte infiltration, and cytoplasmic vacuolation, in the livers of mice treated with BHPF at dosages of 2 mg/kg bw/3-day and higher for 36 days. Microarray analyses revealed 2623 differentially expressed genes (DEGs) in the livers of mice treated with 50 mg/kg bw/day of BHPF for 3 days, which could be enriched in GO terms of T cell activation, leukocyte migration, and leukocyte chemotaxis and KEGG pathways of natural killer cell-mediated cytotoxicity and autoimmune thyroid disease. The top 10 hub DEGs, including LTF and MMP8, were observed in the protein-protein interaction network obtained via STRING database analysis, and are proposed as potential biomarkers for liver injury studies. Primary hepatocyte experiments demonstrated the hepatotoxicity of BHPF at concentrations of 10−6 M and higher. This study indicates that BHPF could cause liver injury at relatively low levels, suggesting that the risk of human BHPF exposure should be of concern.

Bisphenol A is used in the production of many plastic products, but has adverse health effects and is therefore being replaced. Here the authors show that its substitute, fluorene-9-bisphenol, is released from commercial plastic bottles into drinking water, and has anti-oestrogenic effects in mice.

The clear understanding of hydraulic fracture network complexity and the optimization of fracture network configuration are important to the hydraulic fracturing treatment of shale gas reservoirs. For the prediction of hydraulic fracture network configuration, one of the problems is the accurate representation of natural fractures. In this work, a real natural fracture network is reconstructed from shale samples. Moreover, a virtual fracture system is proposed to simulate the large number of small fractures that are difficult to identify. A numerical model based on the displacement discontinuity method is developed to simulate the fluid-rock coupling system. A dimensionless stress difference that is normalized by rock strength is proposed to quantify the anisotropy of crustal stress. The hydraulic fracturing processes under different stress conditions are simulated. The most complex fracture configurations are obtained when the maximum principle stress direction is perpendicular to the principle natural fracture direction. In contrast, the worst results are obtained when these two directions are parallel to each other. Moreover, the side effects of the unfavorable geological conditions caused by crustal stress anisotropy can be partly suppressed by increasing the viscous effect of the fluid.

The formation of dense spacing fracture network is crucial to the hydraulic fracturing treatment of unconventional reservoir. However, one difficulty for fracturing treatment is the lack of clear understanding on the nature of fracture complexity created during the treatment. In this paper, fracture propagation is numerically investigated to find the conditions needed for the stable propagation of complex fracture network. Firstly, starting from a parallel fracture system, the stability of fracture propagation is analyzed and a dimensionless number M is obtained. Then, by developing a hydraulic fracturing simulation model based on displacement discontinuity method, the propagation of parallel fractures is simulated and a clear relation between M and the stability of parallel fractures is obtained. Finally, the investigation on parallel fractures is extended to complex fracture networks. The propagation of complex fracture networks is simulated and the results show that the effects of M on complex fracture networks is the same to that of parallel fractures. The clear relation between M and fracture propagation stability is important for the optimization of hydraulic fracturing operation.

Triclosan (TCS) is a broad-spectrum antimicrobial agent that is frequently used in pharmaceuticals and personal care products. Reports have shown that TCS is a potential endocrine disruptor; however, the potential effects of TCS on placental endocrine function are unclear. The aim of this study was to investigate the endocrine disrupting effects of TCS on the placenta in pregnant rats. Pregnant rats from gestational day (GD) 6 to GD 20 were treated with 0, 30, 100, 300 and 600 mg/kg/d TCS followed by analysis of various biochemical parameters. Of the seven tissues examined, the greatest bioaccumulation of TCS was observed in the placenta. Reduction of gravid uterine weight and the occurrence of abortion were observed in the 600 mg/kg/d TCS-exposed group. Moreover, hormone detection demonstrated that the serum levels of progesterone (P), estradiol (E2), testosterone (T), human chorionic gonadotropin (hCG) and prolactin (PRL) were decreased in groups exposed to higher doses of TCS. Real-time quantitative reverse transcriptase-polymerase chain reaction (Q-RT-PCR) analysis revealed a significant increase in mRNA levels for placental steroid metabolism enzymes, including UDP-glucuronosyltransferase 1A1 (UGT1A1), estrogen sulfotransferase 1E1 (SULT1E1), steroid 5α-reductase 1 (SRD5A1) and steroid 5α-reductase 2 (SRD5A2). Furthermore, the transcriptional expression levels of progesterone receptor (PR), estrogen receptor (ERα) and androgen receptor (AR) were up-regulated. Taken together, these data demonstrated that the placenta was a target tissue of TCS and that TCS induced inhibition of circulating steroid hormone production might be related to the altered expression of hormone metabolism enzyme genes in the placenta. This hormone disruption might subsequently affect fetal development and growth.

In this paper, configurations of pre-existing fractures in cubic rock blocks were investigated and reconstructed for the modeling of experimental hydraulic fracturing. The fluid-rock coupling process of hydraulic fracturing was simulated based on the displacement discontinuities method. The numerical model was validated against the related laboratory experiments. The stimulated fracture configurations under different conditions can be clearly shown using the validated numerical model. First, a dominated fracture along the maximum principle stress direction is always formed when the stress difference is large enough. Second, there are less reopened pre-existing fractures, more newly formed fractures and less shear fractures with the increase of the cohesion value of pre-existing fractures. Third, the length of the stimulated shear fracture decreases rapidly with the increase of the friction coefficient, while the length of the tensile fracture has no correlation to the fiction coefficient. Finally, the increase of the fluid injection rate is favorable to the formation of a fracture network. The unfavorable effects of the large stress difference and the large cohesion of pre-existing fractures can be partly suppressed by an increase of the injection rate in the hydraulic fracturing treatment. The results of this paper are useful for understanding fracture propagation behaviors during the hydraulic fracturing of shale reservoirs with pre-existing fractures.

Shear fracture network is important to the hydraulic fracturing treatment of a shale gas reservoir. In this paper, the formation of shear fracture network is investigated by a Displacement Discontinuity Method (DDM) based model. The results show that the sliding of fracture surface is irreversible but may change significantly after fluid pressure dissipates. The final sliding distance is different for natural and hydraulic fractures. Most of the shear fractures are natural fractures while the newly formed hydraulic fractures tend to be totally closed after pressure dissipates. The effects of in situ stress are investigated. The affected area reaches its maximum value when the maximum principle stress direction is perpendicular to the principal fracture direction. The effects of the injection rate are also investigated. The increasing of the injection rate is helpful in increasing the fracture aperture, but has no effect on the final sliding distance. Moreover, the effects of the injection rate on the affected area depend on the connectivity of natural fractures. The affected area increases with the injection rate when the connectivity is poor but decreases slightly with injection rate when the connectivity is good.

Numerical simulation is very useful for understanding the hydraulic fracturing mechanism. In this paper, we simulate the hydraulic fracturing using the distinct element approach, to investigate the effect of some critical parameters on hydraulic fracturing characteristics. The breakdown pressure obtained by the distinct element approach is consistent with the analytical solution. This indicates that the distinct element approach is feasible on modeling the hydraulic fracturing. We independently examine the influence of in-situ stress ratio, injection rate and fluid viscosity on hydraulic fracturing. We further emphasize the relationship between these three factors and their contributions to the hydraulic fracturing. With the increase of stress ratio, the fracture aperture increases almost linearly; with the increase of injection rate and fluid viscosity, the fracture aperture and breakdown pressure increase obviously. A low value of product of injection rate and fluid viscosity (i.e., Qμ) will lead to narrow fracture aperture, low breakdown pressure, and complex or dispersional hydraulic fractures. A high value of Qμ would lead wide fracture aperture, high breakdown pressure, and simple hydraulic fractures (e.g., straight or wing shape). With low viscosity fluid, the hydraulic fracture geometry is not sensitive to stress ratio, and thus becomes a complex fracture network.

BackgroundRadiotherapy kills tumor-cells by inducing DNA double strand breaks (DSBs). However, the efficient repair of tumors frequently prevents successful treatment. Therefore, identifying new practical sensitizers is an essential step towards successful radiotherapy. In this study, we tested the new hypothesis: identifying the miRNAs to target DNA DSB repair genes could be a new way for sensitizing tumors to ionizing radiation.Principal findingsHERE, WE CHOSE TWO GENES: DNA-PKcs (an essential factor for non-homologous end-joining repair) and ATM (an important checkpoint regulator for promoting homologous recombination repair) as the targets to search their regulating miRNAs. By combining the database search and the bench work, we picked out miR-101. We identified that miR-101 could efficiently target DNA-PKcs and ATM via binding to the 3'- UTR of DNA-PKcs or ATM mRNA. Up-regulating miR-101 efficiently reduced the protein levels of DNA-PKcs and ATM in these tumor cells and most importantly, sensitized the tumor cells to radiation in vitro and in vivo.ConclusionsThese data demonstrate for the first time that miRNAs could be used to target DNA repair genes and thus sensitize tumors to radiation. These results provide a new way for improving tumor radiotherapy.