Nonlinear FEM Analysis on Composite Beams with Web Opening Under Negative Bending Moment

In order to investigate the shear behaviour and main factors of steel-concrete composite beam with web opening under negative moment, simply supported composite beam under concentrated load was analysis through finite element method. The finite element software ANSYS is used to calculate and analyse nonlinearly ten specimens. The main changing parameters are thickness, reinforcement ratio of slab and size of opening. The analysis indicates that stiffness and ultimate capacity will reduce greatly after web opening under negative bending moment. Through increasing the thickness of concrete slab, its bearing capacity can be enhanced markedly, and increasing the reinforcement ratio of concrete slab can improve its deformability effectively. Concrete slab makes a great contribution to shear capacity of web opening composite beam under negative moment. With the increase of the height or width of opening, the shear force that concrete slab undertakes will increase relatively

Objective identification and forecast method of PM2.5 pollution based on medium- and long-term ensemble forecasts in Beijing-Tianjin-Hebei region and its surrounding areas

Accurate long-term forecasts of PM2.5 pollution are essential to mitigating health risks and formulating pollutant control strategies for decision-makers in China. In this study, an objective identification and forecast method for PM2.5 pollution (OIF-PM2.5) is developed based on medium- and long-term ensemble forecasts of PM2.5 in Beijing-Tianjin-Hebei region and its surrounding areas. The results show that the observed PM2.5 pollution ratio increases with the aggravating PM2.5 pollution. For example, the ratio of meteorological stations with heavy pollution is 4.4 times that of light pollution and 3.9 times that of moderate pollution. In addition, the correlation coefficients between observations and forecasts are above 0.60 for all forecast leading times. Statistical results show that the average accuracy for forecasts with the leading times of 1–3 days, 4–7 days, and 8–15 days are 74.1%, 81.3%, and 72.9% respectively, indicating that the OIF-PM2.5 method has a high reliability in forecasts with the leading times of 1–15 days. The OIF-PM2.5 method is further applied in a severe PM2.5 pollution episode in the December of 2021, and the average forecast precision in forecasts with the leading times of 6–8 days reaches as high as 100%, showing a certain reference value for PM2.5 forecasts

Time scales of epidemic spread and risk perception on adaptive networks

Incorporating dynamic contact networks and delayed awareness into a contagion model with memory, we study the spreading patterns of infectious diseases in connected populations. It is found that the spread of an infectious disease is not only related to the past exposures of an individual to the infected but also to the time scales of risk perception reflected in the social network adaptation. The epidemic threshold $p_{c}$ is found to decrease with the rise of the time scale parameter s and the memory length T, they satisfy the equation $p_{c} =\frac{1}{T}+ \frac{\omega T}{a^s(1-e^{-\omega T^2/a^s})}$. Both the lifetime of the epidemic and the topological property of the evolved network are considered. The standard deviation $\sigma_{d}$ of the degree distribution increases with the rise of the absorbing time $t_{c}$, a power-law relation $\sigma_{d}=mt_{c}^\gamma$ is found

Wu Shan Shen Cha (Malus asiatica Nakai. Leaves)-Derived Flavonoids Alleviate Alcohol-Induced Gastric Injury in Mice via an Anti-Oxidative Mechanism

Wu Shan Shen Cha is the leaf of Malus asiatica Nakai., a special type of tea that is consumed in the same way as green tea. To study the effect of Wu Shan Shen Cha-derived flavonoids (WSSCF) on lesions in the stomach, a 15% hydrochloric acid–95% ethanol (volume ratio 4:6) solution was used to induce gastric injury in mice. The degree of gastric injury was assessed using tissue specimens, and the effects of WSSCF on the serum levels of antioxidant enzymes were investigated. The results showed that WSSCF could alleviate the damage of the gastric mucosa and gastric wall caused by the hydrochloric acid–ethanol solution, decrease the tissue and serum levels of malondialdehyde (MDA) in mice with gastric injury, and increase the serum levels of superoxide dismutase (SOD) and glutathione (GSH). The results of quantitative polymerase chain reaction (qPCR) showed that WSSCF could increase the mRNA expression of Mn-SOD, Cu/Zn-SOD, catalase (CAT), endothelial nitric oxide synthase (eNOS), and neuronal nitric oxide synthase (nNOS) in tissue specimens from mice with gastric injury and decrease the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). At the same time, the results of the high concentration of WSSCF (WSSCFH) group were closer to those of the drug (ranitidine) treatment group. Wu Shan Shen Cha-derived flavonoids had a good antioxidant effect, so as to play a preventive role in alcoholic gastric injury

Correlations between two sets of angular relation equations

It is shown here that the angular relation equations between direct and reciprocal vectors are very similar to the angular relation equations in Euler's theorem. These two sets of equations are usually treated separately as unrelated equations in different fields. In this careful study, the connection between the two sets of angular equations is revealed by considering the cosine rule for the spherical triangle. It is found that understanding of the correlation is hindered by the facts that the same variables are defined differently and different symbols are used to represent them in the two fields. Understanding the connection between different concepts is not only stimulating and beneficial, but also a fundamental tool in innovation and research, and has historical significance. The background of the work presented here contains elements of many scientific disciplines. This work illustrates the common ground of two theories usually considered separately and is therefore of benefit not only for its own sake but also to illustrate a general principle that a theory relevant to one discipline can often be used in another. The paper works with chemistry related concepts using mathematical methodologies unfamiliar to the usual audience of mainstream experimental and theoretical chemists

Synthesis of New C2-Symmetric Six-Membered NHCs and Their Application for the Asymmetric Diethylzinc Addition of Arylaldehydes

A concise method for the preparation of new 3,4,5,6-tetrahydropyrimidinium salts was presented in this paper. Further application of these salts in asymmetric diethylzinc addition of arylaldehydes was explored, giving the corresponding chiral second alcohols in good yields and moderate enantioselectivities

The Influence of Lactic Acid Bacteria from Xinjiang Traditional Fermented Yogurt on Antioxidation of Geniposide in vitro

To investigate the influence of lactic acid bacteria on the antioxidant effect of geniposide in vitro, seven strains of lactic acid bacteria were isolated from natural fermented yoghurt from Xinjiang, China. Lactic acid bacteria, geniposide and their mixtures were used separately to evaluate the antioxidant effect through detecting the scavenging activity of 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH), Hydroxyl free radicals and 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS). The results showed that, compared with the group that geniposide separately used, the strains numbered x70-1, x70-2, x70-3, x70-4 and x70-5, combined with geniposide had more remarkable antioxidant effect, while the other two strains (numbered x43-2 and x43-3)combined with geniposide showed low oxidation resistance. These results may provide a potential method to promote antioxidant effect of geniposide

Preventive Effect of Blueberry Extract on Liver Injury Induced by Carbon Tetrachloride in Mice

The blueberry is a common fruit that is rich in nutritional value and polyphenol substances. In this study, the blueberry polyphenol content in extract was analysed by spectrophotometry. The results showed that the blueberry polyphenol content in the extract reached 52.7%. A mouse model of liver injury induced by carbon tetrachloride (CCl4) was established to study the preventive effect of blueberry extract (BE) on liver injury in mice and the experimental animals were examined using biochemical and molecular biological methods. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are important clinical liver function indicators; the changes of triglyceride (TG) and total cholesterol (TC) are observed after liver injury; interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) are important inflammatory indexes; superoxide dismutase (SOD) activity and thiobarbituric acid reactive substances (TBARS) are important changes of oxidative stress indexes. The in vivo animal experiment results showed that BE decreased the liver index of mice with liver injury, BE could reduce the AST, ALT, TG and TC levels and also could reduce the serum cytokine IL-6, TNF-α and IFN-γ levels in mice with liver injury. Moreover, BE increased the SOD activity and decreased the TBARS level in the gastric tissues of mice with liver injury. After treatment with the highest concentration of BP in liver injury mice, these levels returned close to those obtained after treatment with the standard drug of silymarin. Detection of messenger RNA (mRNA) in liver tissue showed that BE upregulated the Cu/Zn-SOD, Mn-SOD and chloramphenicol acetyltransferase (CAT) expression levels and downregulated cyclooxygenase (COX)-2 expression. The effect of BE on mice with liver injury was positively correlated with the BE concentration and was similar to that of silymarin, which is a drug for liver injury, suggesting that BE had a good preventive effect on liver injury. Thus, BE rich in polyphenols is a bioactive substance with value for development and utilization