The Reform of Elastic-plastic Mechanics Teaching for Petroleum Engineering Related Majors

“Elastic-plastic Mechanics” is an important course for undergraduates and postgraduates of general engineering majors. However, the theoretical derivation of equations is complex, and the connection with engineering practice is inadequate. Therefore, teaching becomes difficult and boring for a number of students. Firstly, this paper introduces the importance of Elastic-plastic Mechanics for petroleum engineering related majors. Based on the recent teaching experience, the teaching reform of Elastic-plastic Mechanics course is carried out focusing on teaching method and learning content, and a discussion teaching mode based on students’ independent discussion and engineering cases is formed. Remarkable results have been achieved in improving students’ learning efficiency and classroom teaching effect. Furthermore, students’ comprehensive ability of independent innovation and practice is enhanced

A Multi-scale Approach to Investigating the Wintering Habitat Selection of Red-crowned Cranes in the Yancheng Nature Reserve, China

A B S T R A C T The red-crowned crane (Grus japonensis) is a rare and endangered species that lives in wetland habitats. In this study, we first compared crane habitat selection in December, 2013 and January, 2014 using the Neu method in the Yancheng National Reserve (YNR). We then explored the relative importance of habitats (plot, landscape) and spatial factors on red-crowned crane abundance at multiple scales using regression models and variation partitioning approaches. Our results indicated that seepweed (Suaeda salsa) tidal flats and reed ponds were the favored habitats by cranes in December and January, respectively. The variation partitioning results indicated that plot and landscape factors were the determining factors of crane abundance in December, but plot features were more important in January. Furthermore, the pure and total effects of plot factors, and the combined effects of plot, landscape and spatial factors, increased significantly from December to January. At plot scale, vegetation coverage and road distance were the crucial variables that determine crane abundance in both months. At landscape scale, percentage of reed ponds and percentage of seepweed tidal flats showed a positive independent effect on crane abundance in both months. Percentage of paddy fields was also a significant variable in December, whereas percentage of fishponds was in January. Our study indicated that crane habitat selection and the determining factors changed over time due to food availability and human disturbance (e.g., reed pond and fishpond harvests). Our results encourage the application of partitioning methods in avian ecology because they provide a more in-depth understanding of the importance of different explanatory variables over traditional regression methods. Efforts should be made to strengthen wetland restoration and improve the mitigation of human disturbance in the YNR

Proteins of the food-borne pathogen <i>Listeria monocytogenes</i> strain F2365 relevant to lethal acidic stress and during rapid inactivation

Listeria monocytogenes, which causes human listeriosis after consumption of contaminated food, can adapt and survive under a wide range of physiological and chemical stresses. In this study, the overall proteomic response of the L. monocytogenes strain F2365—a strain with mutations limiting its ability to tolerate acidic conditions—to progressive non-thermal acidic inactivation was investigated. The challenge process was investigated in the early stationary growth phase where F2365 cultures were acidified (pH 3.0, HCl) at 5 min, 1 h, and 2 h, generating pH 4.8, pH 4.1, and pH 3.5, respectively, with protein abundance measured using iTRAQ. Approximately 73 proteins increased in abundance and 8 declined when acidic stress became non-growth-permissive (pH &lt; 4.1) and inactivation accelerated to approximately 2 log units/h. The functional categories of responding proteins were broad but the proteins involved were specific in nature and did not include whole pathways. Many responses likely accentuate energy conservation and compensate vital metabolic processes. For example, further repression of FlaA, normally repressed under acidic stress, occurs accompanied by an increase in quinol oxidase subunit QoxA and glycerol kinase GlpK. Proteins maintaining cell wall integrity, such as Iap and CwlO, manifested the overall largest abundance increase trend. Virulence proteins were also induced, including InlA, InlC, Hyl, Mpl, PlcA, and PlcB, suggesting that acidification may have mimicked conditions inducing some host survival traits. The overall suite of proteins affected appears to be the "last ditch" responses to non-thermal inactivation above and beyond the standard protections afforded in the stationary-growth phase. The array of proteins found here may provide a deeper understanding of the physiological responses of this pathogen during non-thermal inactivation

Research on influencing factors and remedial measures of coal seam water blocking effect

Coalbed methane development primarily relies on hydraulic fracturing and drainage gas extraction processes. The intrusion of external fluids and long-term drainage and extraction contribute to the water blocking effect, which becomes one of the crucial factors affecting production capacity. In this study, the coal reservoir of a certain coalbed methane in Hancheng, Shaanxi Province, was selected as the research object. The experimental method was employed to comprehensively evaluate the correlation between factors such as coal sample moisture content, permeability, porosity, properties of external liquids, and water blocking damage. The results indicated that there was a positive correlation between coal sample moisture content, liquid surface tension, and water blocking damage. On the other hand, coal sample pore permeability characteristics, liquid contact angle with rock samples, and water blocking damage showed a negative correlation. Building upon the aforementioned research, an investigation into remedial measures for water blocking damage was conducted. Additionally, a chemical treatment study using the compound surfactant system JSS-1 as a water-blocking agent was performed to manage the water blocking effect. The results demonstrated that JSS-1 as a water-blocking agent significantly reduced the surface tension of the wellbore fluid and improved its wetting behavior on the coal-rock surface. The laboratory experiments confirmed the capability of JSS-1 in managing the water blocking effect

Tutorial introdutório do Port4NooJ

Background: Plakophilin2 (PKP2) is a desmosome-related protein with numerous armadillo repeats and has been linked to arrhythmogenic right ventricular cardiomyopathy (ARVC). Fatal arrhythmias resulting in sudden death also occur in the absence of morphologic cardiac abnormalities at autopsy, and have been linked to ion channel mutations in a subset of cases, but so far not to PKP2.Methods and Results: We sequenced all 14 exons of PKP2 in DNA extracted from postmortem heart tissues of 25 patients dying from ARVC and 25 from sudden unexpected death with negative autopsy (SUDNA). the primers were designed using the Primer Express 3.0 software. Direct sequencing for both sense and antisense strands was performed with a BigDye Terminator DNA sequencing kit on a 3130XL Genetic Analyzer. Mutation damage prediction was made using Mutation Taster, Polyphen and SIFT software. in 6 of the 25 ARVC samples, 6 PKP2 mutations were identified, 4 of which were likely significant, and 3 of which were novel (p.N641del, p.L64PfsX22, p.G269R). in 6 of the 25 cases of SUDNA samples, 6 PKP2 mutations were identified, 3 of which were likely significant, and 4 of which were not previously described (p.P665S, p.Y217TfsX45, p.E540, p.S615T).Conclusions: PKP2 mutations are not specific for ARVC and may result in SUDNA. the link between ARVC and desmosomal mutations may not be causal but related to an association between defective desmosomal proteins and arrhythmias. (Circ J 2012; 76: 189-194

Preparation and Characterization of Superabsorbent Polymers Based on Sawdust

Sawdust, a cheap by-product of the timber and forestry industry, was considered as a framework structure to prepare superabsorbent polymer with acrylic acid (AA) and acrylamide (AM), the synthetic monomers. The effects of initiator content, crosslinker content, AA content, AM content, degree of neutralization of AA, and reaction temperature on the swelling rate of superabsorbent polymer were investigated. The synthesized polymer was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Under optimal synthesis conditions, the results showed that the swelling rate of the polymer in deionized water and 0.9% NaCl solution reached 738.12 and 90.18 g/g, respectively. The polymer exhibits excellent swelling ability, thermal stability, and reusability. After the polymer was introduced into the samples (soil or coal), the water evaporation rate of the samples was significantly reduced, and the saturated water holding capacity and pore structure were also significantly improved

TDA-Net: A Novel Transfer Deep Attention Network for Rapid Response to Building Damage Discovery

The rapid and accurate discovery of damage information of the affected buildings is of great significance for postdisaster emergency rescue. In some related studies, the models involved can detect damaged buildings relatively accurately, but their time cost is high. Models that can guarantee both detection accuracy and high efficiency are urgently needed. In this paper, we propose a new transfer-learning deep attention network (TDA-Net). It can achieve a balance of accuracy and efficiency. The benchmarking network for TDA-Net uses a pair of deep residual networks and is pretrained on a large-scale dataset of disaster-damaged buildings. The pretrained deep residual networks have strong sensing properties on the damage information, which ensures the effectiveness of the network in prefeature grasping. In order to make the network have a more robust perception of changing features, a set of deep attention bidirectional encoding and decoding modules is connected after the TDA-Net benchmark network. When performing a new task, only a small number of samples are needed to train the network, and the damage information of buildings in the whole area can be extracted. The bidirectional encoding and decoding structure of the network allows two images to be input into the model independently, which can effectively capture the features of a single image, thereby improving the detection accuracy. Our experiments on the xView2 dataset and three datasets of disaster regions achieve high detection accuracy, which demonstrates the feasibility of our method

Graphitic carbon nitride with thermally-induced nitrogen defects: an efficient process to enhance photocatalytic H2production performance

Graphitic carbon nitride (g-C3N4, CN) with nitrogen vacancies was synthesized by a controlled thermal etching method in a semi-closed air-conditioning system. The defect-modified g-C3N4shows an excellent photocatalytic performance demonstrated by water splitting under visible light irradiation. With proper heat-treatment durations such as 2 h (CN2) and 4 h (CN4) at 550 °C, the hydrogen production rates significantly increase to 100 µmol h-1and 72 µmol h-1, which are 11 times and 8 times the rate of the pristine CN (8.8 µmol h-1) respectively. The excellent hydrogen production performance of nitrogen defect modified CN2 is due to the synergy effect of the decreased band gap, enlarged specific surface area and increased separation/migration efficiency of photoinduced charge carriers. This simple defect engineering method provides a good paradigm to improve the photocatalytic performance by tailoring the electronic and physical structures of g-C3N4

Topography- and Species-Dependent Climatic Responses in Radial Growth of Picea meyeri and Larix principis-rupprechtii in the Luyashan Mountains of North-Central China

Dendroecological techniques were used to examine the relationships between topographic aspects, climate factors and radial growth of Picea meyeri and Larix principis-rupprechtii in Luyashan Mountains, North-Central China. Four sites were selected at timberline and totally 67 trees and 134 cores were collected. Pearson correlation and regression surface analysis were conducted to reveal the growth-climate relationships. The results indicated that the two species both showed significant negative correlations with temperature during preceding November on the two topographic aspects. On both slope aspects, growth of P. meyeri exhibited significant negative correlations with precipitation in current June, whereas growth of L. principis-rupprechtii showed significant negative correlations with precipitation in preceding September. On north-facing slope, tree growth was limited by low temperature in early growing season, which not shown on south-facing slope. If climate warming continues, L. principis-rupprechtii may be more favored and a reverse between relationships with temperature and precipitation maybe occur in growth of trees. Treeline position on the north-facing slope may possess a greater potential for elevation shifting than the south-facing slope. Our results supply useful information for discussing the potential effect of future climate on the forest growth in North-Central China

Estimating Loess Plateau Average Annual Precipitation with Multiple Linear Regression Kriging and Geographically Weighted Regression Kriging

Estimating the spatial distribution of precipitation is an important and challenging task in hydrology, climatology, ecology, and environmental science. In order to generate a highly accurate distribution map of average annual precipitation for the Loess Plateau in China, multiple linear regression Kriging (MLRK) and geographically weighted regression Kriging (GWRK) methods were employed using precipitation data from the period 1980–2010 from 435 meteorological stations. The predictors in regression Kriging were selected by stepwise regression analysis from many auxiliary environmental factors, such as elevation (DEM), normalized difference vegetation index (NDVI), solar radiation, slope, and aspect. All predictor distribution maps had a 500 m spatial resolution. Validation precipitation data from 130 hydrometeorological stations were used to assess the prediction accuracies of the MLRK and GWRK approaches. Results showed that both prediction maps with a 500 m spatial resolution interpolated by MLRK and GWRK had a high accuracy and captured detailed spatial distribution data; however, MLRK produced a lower prediction error and a higher variance explanation than GWRK, although the differences were small, in contrast to conclusions from similar studies