Simulation of a Gas Tungsten Arc Welding Process in COMSOL

The purpose of this project is to model the transport phenomena (heat transfer, fluid flow, and current flow) in a gas tungsten arc welding (GTAW) process using COMSOL Multiphysics. The model development will start with developing two separate models - an arc model and a weld pool model and end with an integrated arc - weld pool model to simulate the interaction between the arc and the weld pool. The integrated arc-weld pool model will be used to study the effects of some welding process parameters, such as the anode materials, the arc length, and the shielding gas, on the final weld quality

Mechanism of Polarization Fatigue in BiFeO3: the Role of Schottky Barrier

By using piezoelectric force microscopy and scanning Kelvin probe microscopy, we have investigated the domain evolution and space charge distribution in planar BiFeO3 capacitors with different electrodes. It is observed that charge injection at the film/electrode interface leads to domain pinning and polarization fatigue in BiFeO3. Furthermore, the Schottky barrier at the interface is crucial for the charge injection process. Lowering the Schottky barrier by using low work function metals as the electrodes can also improve the fatigue property of the device, similar to what oxide electrodes can achieve

Explicit original gas in place determination of naturally fractured reservoirs in gas well rate decline analysis

Naturally fractured gas reservoirs have contributed significantly to global gas reserves and production. The classical gas-well decline analysis relies largely on Arps’ empirical decline models, or modern production decline analysis associating with pseudo-variables. The explicit original gas in place determination methodology is extended from homogeneous reservoir to naturally fractured reservoir under constant or variable bottom-hole pressure conditions in gas-well rate decline analysis. Then, the relationship between gas flow rate and average reservoir pseudo-pressure in the boundary-dominated flow period is re-derived. This formula is in the same format with the equation for homogeneous reservoir by due to the introduction of a new productivity index parameter that captures the inter-porosity flow between fracture and matrix in the natural fractured reservoir. The proposed step-by-step procedures are applied here, which enable the estimation of decline exponent and the explicit and straightforward determination of the original gas in place without any iterative calculations. Four simulated cases prove that our methodology can be successfully used in heterogeneous naturally fractured reservoirs with irregular boundary under constant or variable bottom-hole pressure conditions.Document Type: Original articleCited as: Wang, Y., Wang, J., Zhao, W., Ji, P., Cheng, S., Yu, H. Explicit original gas in place determination of naturally fractured reservoirs in gas well rate decline analysis. Advances in Geo-Energy Research, 2023, 9(2): 117-124. https://doi.org/10.46690/ager.2023.08.0

Pretreatment with antiplatelet drugs improves the cardiac function after myocardial infarction without reperfusion in a mouse model

Background: Reperfusion therapy is known to improve prognosis and limit myocardial damage aftermyocardial infarction (MI). The administration of antiplatelet drugs prior to percutaneous coronaryintervention also proves beneficial to patients with acute MI (AMI). However, a good number of AMIpatients do not receive reperfusion therapy, and it is not clear if they would benefit from antiplateletpre-treatment.Methods: Experimental C57BL/6 mice were randomly allocated to five groups: the sham group,control, post-treatment, pre-treatment, and pre- and post-treatment groups. Acetylsalicylic acid (15 mg/kg), clopidogrel (11 mg/kg), ticagrelor (27 mg/kg), and prasugrel (1.5 mg/kg) were intragastrically administered in the treatment groups. On day 7 post MI, cardiac function and cardiac fibrosis were evaluated using echocardiography and Masson’s trichrome staining, respectively. Histopathological examinations were performed on tissue sections to grade inflammatory cell infiltration. Platelet inhibition was monitored by measuring thrombin-induced platelet aggregation.Results: Left ventricular ejection fraction and fractional shortening improved significantly (p < 0.01)in the pre-treatment groups when compared to the post-treatment and control groups. A significant(p < 0.01) decrease in cardiac fibrosis was observed in the pre-treatment group, compared with the posttreatment and control groups. Inflammatory cell infiltration significantly decreased in the pre-treatment group compared with the control group (p < 0.05). Thrombin-induced platelet aggregation was significantly inhibited by antiplatelet drugs, but increased with the exposure to H2O2.Conclusions: In the absence of reperfusion therapy, pre-treatment with antiplatelet drugs successfullyimproved cardiac function, reduced cardiac fibrosis and inflammatory cell infiltration, and inhibited oxidative stress-induced platelet aggregation after MI in the mouse model

College students’ knowledge, attitudes, and practices of garbage sorting and their associations: a cross-sectional study of several universities in Beijing, China

BackgroundIn recent years, the Chinese government has placed growing emphasis on environmental development. The implementation of effective waste separation practices in schools is crucial for establishing an ecological civilization in China.ObjectiveThe present study aimed to assess the knowledge, attitude, and practice (KAP) of waste separation among Chinese university students and to understand the demographic factors influencing the KAP of the interviewed students. These sociodemographic factors include gender, age, education, and family environment.MethodsBased on the KAP theoretical model and the Lewin behavioral model (LBM), this study developed its questionnaire on college students’ KAP of rubbish sorting. A survey was conducted on 1,282 college students from five colleges and universities in Beijing. A one-way ANOVA, Pearson’s correlation analysis, and multiple linear stepwise regression analyzes were employed to explore the factors influencing college students’ KAP scores on waste sorting. The questionnaire’s reliability and validity were effectively verified through two rounds of Delphi expert consultation.ResultsThe scores for KAP dimensions were 55.64, 69.18, and 54.8%, respectively. The overall KAP score of university students in waste classification was 46.93 ± 9.93, with a percentage score of 62.57%. More than half of the college students lack a clear understanding of waste classification. Grade, gender, major, highest family education, and family economic status all influence college students’ KAP scores on waste classification. There is a notable deficiency in school education regarding waste classification, with only 30.7% reporting having received such education.ConclusionThis study unveils the overall KAP score of waste separation among Chinese college students, which is marginally acceptable. The interviewed students exhibit a positive attitude and a willingness to participate in waste separation. However, there is room for improvement in both knowledge and practices. A lack of knowledge about waste sorting emerges as the primary influence on individual-level practices. Consideration should be given to enhancing education and management of waste separation among college students, emphasizing the cultivation of an eco-conscious culture, and guiding students to establish correct ecological values

The genome of the Hi5 germ cell line from Trichoplusia ni, an agricultural pest and novel model for small RNA biology

We report a draft assembly of the genome of Hi5 cells from the lepidopteran insect pest, Trichoplusia ni, assigning 90.6% of bases to one of 28 chromosomes and predicting 14,037 protein-coding genes. Chemoreception and detoxification gene families reveal T. ni-specific gene expansions that may explain its widespread distribution and rapid adaptation to insecticides. Transcriptome and small RNA data from thorax, ovary, testis, and the germline-derived Hi5 cell line show distinct expression profiles for 295 microRNA- and \u3e 393 piRNA-producing loci, as well as 39 genes encoding small RNA pathway proteins. Nearly all of the W chromosome is devoted to piRNA production, and T. ni siRNAs are not 2 -O-methylated. To enable use of Hi5 cells as a model system, we have established genome editing and single-cell cloning protocols. The T. ni genome provides insights into pest control and allows Hi5 cells to become a new tool for studying small RNAs ex vivo