Liaoning Provincial Institute of Agricultural Mechanization

With the large-scale construction and long-term operation of underground reservoirs in coal mines, the problem of surrounding rock stability under long-term water immersion has become increasingly prominent. Therefore, clarifying the dynamic response of rocks under long-term immersion and impact loads is of great theoretical significance for ensuring the safe operation of coal mine reservoirs throughout their entire life cycle. In this study, sandstone samples were immersed in water for 0, 3, 30, 90 and 180 days respectively. The microstructure characterization and dynamic tests were carried out by using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), computed tomography (CT), and an improved separated Hopkinson compression bar (SHPB) system. The results show that: (1) The combined results of SEM, NMR and CT tests indicate long-term impregnation reduces the proportion of micropores and increases the proportion of mesopores and macropores. The total dissolved solids (TDS) concentration in the impregnating solution increases with time, and the pH value of the solution first rises and then decreases with the extension of the immersion time. (2) The faster the impact velocity, the greater the frequency and amplitude of the stress wave generated. The water saturation gradually increases with immersion, weakening the discontinuity of acoustic impedance and reducing the reflection coefficient at the interface. (3) The increase in impact velocity intensifies fragmentation and promotes the development of complex fracture networks. With the extension of immersion time, the expansion of clay minerals such as montmorillonite will generate expansion stress, thereby creating micro-cracks, which leads to a higher fractal dimension of the crack network and eventually stabilizes over time. (4) Under the action of impact loads, the proportion of intergranular fractures increases with the extension of immersion time. However, at high impact speeds, the relative strength contrast between the cementing material and quartz particles leads to an increase in transgranular fracture. Overall, this study provides guidance for the safe design and operation of underground reservoirs in coal mines.

Addressing the problem of lacking accurate and reliable contact parameters and bonding parameters in the simulation of the mashing process during the harvesting of alfalfa, this study takes the stems of alfalfa at the harvesting stage as the research object. The geometric dimensions and related intrinsic parameters of the stems were measured. Using the Enhanced Discrete Element Method (EDEM) software, a multi-scale discrete element flexible bonding model of alfalfa stems was established based on region-specific parameters. The entire alfalfa stem was divided into three parts: the top, middle, and root sections. A multi-scale particle aggregation model of hollow stems was created using the Hertz-Mindlin with bonding model. The contact parameters between alfalfa stems at the harvesting stage and PU rubber were determined using a mathematical model based on quadratic polynomial fitting curves. The results showed that the shear modulus of the top, middle, and root sections of the alfalfa stems were 24.96 MPa, 29.60 MPa, and 10.48 MPa, respectively. The coefficients of restitution between the top, middle, and root sections of the alfalfa stems and PU rubber were 0.426, 0.375, and 0.386, respectively; the static friction coefficients were 0.613, 0.667, and 0.422, respectively; and the rolling friction coefficients were 0.213, 0.226, and 0.292, respectively. The relative error between the simulated and measured values of the angle of repose was less than 3%, effectively representing the mechanical characteristics of alfalfa stems at the harvesting stage bending and breaking under impact. This study aims to establish a discrete element flexible model of alfalfa stems at the harvesting stage and accurately calibrate the contact parameters with typical rubber materials, thereby addressing the lack of reliable bonding and contact parameters in existing simulations of the mashing process.

The heterotrophic nitrification aerobic denitrification bacteria (HNDS) can perform nitrification and denitrification at the same time. Two HNDS strains, Achromobacter sp. HNDS-1 and Enterobacter sp. HNDS-6 which exhibited an amazing ability to solution nitrogen (N) removal have been successfully isolated from paddy soil in our lab. When peptone or ammonium sulfate as sole N source, no significant difference in gene expression related to nitrification and denitrification of the strains was found according to the transcriptome analysis. The expression of phosphomethylpyrimidine synthase (thiC), ABC transporter substrate-binding protein, branched-chain amino acid ABC transporter substrate-binding protein, and RNA polymerase (rpoE) in HNDS-1 were significantly upregulated when used peptone as N source, while the expression of exopolysaccharide production protein (yjbE), RNA polymerase (rpoC), glutamate synthase (gltD) and ABC-type branched-chain amino acid transport systems in HNDS-6 were significantly upregulated. This indicated that these two strains are capable of using organic N and converting it into NH4+-N, then utilizing NH4+-N to synthesize amino acids and proteins for their own growth, and strain HNDS-6 can also remove NH4+-N through nitrification and denitrification.

High oleic (HO) peanut (Arachishypogaea L.) oils benefit human health and industrial production due to its superior nutritional composition and thermo-oxidative stability. However, HO peanut is sensitive to cold stress especially during germination, which limits its distribution in low temperature areas. To understand the molecular mechanism of cold responses in HO peanuts at germination stage, four HO peanut varieties with different cold tolerance were selected in field experiments to analyze their genome-wide gene regulation under low temperatures. High-throughput sequencing and transcriptome analysis revealed a total of 139 429 unigenes. Among these, 3520 common differentially expressed genes (DEG) were detected between two groups of cold-tolerant and cold-sensitive peanuts, and the number of up-regulated genes was greater than that of down-regulated genes in the cold-tolerant peanuts. Gene ontology analysis indicates that the number of DEGs involved in cell membrane metabolism and integrity as well as proteins located in the cell periphery were significantly higher in the cold-tolerant peanuts. KEGG pathway analysis suggests that plant-pathogen interaction and plant hormone signal transduction pathway play important roles in cold tolerance. Four cold-induced genes, TIC(TIME FOR COFFEE), ATX3(histone-lysine N-methyltransferase ATX3-like), AGO4(argonaute 4-like), FER(FERONIA-like receptor protein kinase), and three transcription factor genes, bHLH(bHLH49-like transcription factor), MYB(MYB-related protein 3R-1-like)and EREB(Ethylene-responsive element binding factor 6)were selected to verify the expression profile via real-time quantitative PCR detection. The expression of TIC, ATX3, AGO4, bHLH, MYB and EREB significantly increased within 3 hours after low temperature stress, while the expression of FER significantlyincreased after 12 hours, suggesting that these genes responded to low temperature stress during peanut germination. This work not only sheds light on the transcriptional regulation of HO peanut under low-temperature stress during germination but also provides data resources for screening candidate genes in improving peanuts stress resistance.

Abstract With the development of science and technology, reliability of power grids in rural areas in the algorithm have made new progress, in a variety of simulation methods, Monte Carlo simulation method because the sampling frequency has nothing to do with the grid size and the required accuracy only the features, so network security risk management in rural areas has been widely used. This article describes the sequential simulation, non-sequential Monte Carlo simulation of the basic principles of probabilistic simulation methods and characteristics.KeywordsMonte Carlo simulationPower systemRisk assessment