Search

Abstract The Longwall top coal caving (LTCC) technology is regarded as one of the most crucial approaches for exploiting thick coal seams. A crucial and effective approach for improving the recovery rate of top coal and reducing coal resource losses in LTCC faces is to reasonably select process parameters based on actual mining and geological conditions of different mines. The main focus of this paper is the engineering background of the 12,309 LTCC face in Wangjialing Coal Mine. A numerical model is developed using FALC3D and PFC3D software, employing a finite difference method and discrete element method. This model takes into account predetermined cutting and caving ratios, as well as drawing intervals. To examine the caving process and roof particles, three different drawing sequences were examined: sequential drawing, segmented sequential drawing, and intermittent drawing. The findings suggest that, in terms of the reset shape of the drawing body before individual and entire caving, the segmented sequential drawing method exhibits noticeable drawbacks compared to the other two methods. From the perspective of the drawing weight, following “closing drawing opening when seeing gangue”, the sequential drawing, segmented sequential drawing, and intermittent drawing methods can yield 32.42 t, 26.87 t, and 35.78 t of top coal, with corresponding recovery rates of 73.39%, 60.81%, and 82.97%. Therefore, it can be concluded that intermittent drawing is suitable for implementation on LTCC working face 12,309.

BACKGROUND: Currently, many emerging polycyclic aromatic hydrocarbons (PAHs) have been found to be widely present in the environment. However, little has been reported about their toxicity, particularly in relation to CYP1A1. OBJECTIVES: This study aimed to explore the toxicity of naphtho[2,1-a]pyrene (N21aP) and elucidate the mechanism underlying N21aP-induced expression of CYP1A1. METHODS: The concentration and sources of N21aP were detected and analyzed by gas chromatography–triple quadrupole mass spectrometry (GC-MS/ MS) and diagnostic ratio analysis. Then the effects of CYP1A1 on the toxicity of N21aP were conducted in male wild-type (WT) and Cyp1a1 knockout mice exposed to N21aP (0.02, 0.2, and 2 mg/kg) through intratracheal instillation. Further, the aryl hydrocarbon receptor (AhR) pathway was examined through luciferase and chromatin immunoprecipitation (ChIP) assays. 푁6-methyladenosine (m6A) modification levels were measured on global RNA and specifically on CYP1A1 mRNA using dot blotting and methylated RNA immunoprecipitation-quantitative real-time polymerase chain reaction (MeRIP qRT-PCR), with validation by m6A inhibitors, DAA and SAH. m6A sites on CYP1A1 were identified by bioinformatics and luciferase assays, and CYP1A1mRNA’s interaction with IGF2BP3 was confirmed by RNA pull-down, luciferase, and RNA binding protein immunoprecipitation (RIP) assays. RESULTS: N21aP was of the same environmental origin as benzo[a]pyrene (BaP) but was more stably present in the environment. N21aP could be metabolically activated by CYP1A1 to produce epoxides, causing DNA damage and further leading to lung inflammation. Importantly, in addition to the classical AhR pathway (i.e., BaP), N21aP also induced CYP1A1 expression with a posttranscriptional modification of m6A in CYP1A1 mRNA via the METTL14–IGF2BP3–CYP1A1 axis. Specifically, in the two recognition sites of METTL14 on the CYP1A1 mRNA transcript (position at 2700 and 5218), a methylation site (position at 5218) in the 3′-untranslated region (UTR) was recognized by IGF2BP3, enhanced the stability of CYP1A1 mRNA, and finally resulted in an increase in CYP1A1 expression. DISCUSSION: This study systematically demonstrated that in addition to AhR-mediated transcriptional regulation, N21aP, had a new additional mechanism of m6A-mediated posttranscriptional modification, jointly contributing to CYP1A1 expression. Given that PAHs are the metabolic substrates of CYP1A1, this study not only helps to understand the significance of environment–genetic interactions for the toxicity of PAHs but also helps to better understand the health risks of the emerging PAHs at environmental exposure levels. [ABSTRACT FROM AUTHOR]

Privacy protection has become the key problem that blockchain technology must solve from theory to practice. There is a privacy protection requirement of on-demand disclosure in practical applications. Inspired by multicast secure communication mechanism, a privacy protection mechanism of on-demand disclosure on blockchain was proposed. This mechanism improves the RSA based anonymous multi receiver encryption scheme to realize the disclosure of the private data on the blockchain only to the permitted informed, the anonymity protection of the informed and the traceability of the privacy disclosure. The Quorum blockchain privacy protection mechanism is adopted to realize the safe and efficient distribution of the key between the owner of the private information and the informed. Finally, it is proved that PPM-ODB mechanism can guarantee the privacy of privacy data and its superiority in time and storage cost, and it is suggested that the number of informed people should be less than 100 to obtain a good user experience.