ABSTRACT
Based on a 5-point stencil and three 3-point stencils, a nonlinear multi-order weighted method adaptive to 5-3-3-3 stencils for shock capturing is presented in this paper. The form of the weighting function is the same as JS (Jiang-Shu) weighting; however, the smoothness indicator of the 5-point stencil adopts a special design with a higher-order leading term similar to the τ in Z weighting. The design maintains that the nonlinear weights satisfy sufficient conditions for the scheme to avoid degradation even near extreme points. By adjusting the linear weights to a specific value and using the τ in Z weighting, the method can be degraded to Z weighting. Analysis of linear weights shows that they do not affect the accuracy in the smooth region, and they can also adjust the resolution and discontinuity-capturing capability. Numerical tests of different hyperbolic conservation laws are conducted to test the performance of the newly designed nonlinear weights based on the weighted compact nonlinear scheme. The numerical results show that there are no obvious oscillations near the discontinuity, and the resolution of both the discontinuity and smooth regions is better than that of Z weights.
ABSTRACT
Background: Myocardial necrosis caused by myocardial ischemia-reperfusion (MI/R) in diabetic patients is prominently aggravated and can cause oxidative stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a redox-sensing transcription factor that protects against myocardial ischemia/reperfusion injury (MIRI). However, the mechanism of action of Nrf2 in resveratrol-pretreated cardiomyocytes is complex. We assumed that adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/p38 mitogen-activated protein kinases (p38)/Nrf2 might be involved in resveratrol alleviating MIRI in diabetic rats as an endogenous protective mechanism. Methods: A total of 50 type 2 diabetes mellitus (T2DM) rat models were randomly divided into 5 groups (n=10 in each group): sham group; MI/R group; AMPK inhibitor compound C + myocardial ischemia-reperfusion (C + MI/R) group; resveratrol + myocardial ischemia-reperfusion (RSV + MI/R) group; and resveratrol + AMPK inhibitor compound C + myocardium ischemia-reperfusion group (RSV + C + MI/R) group. Rats were fed a high fat diet, and the T2DM models were established by intraperitoneal injection of 1% streptozotocin (STZ). The MIRI models were established by ligating the left anterior descending coronary artery for 30 minutes followed by reperfusion for 120 minutes. The size of myocardial infarction was measured. Serum samples were collected to measure the concentrations of creatine kinase-MB (CK-MB). The levels of lactate dehydrogenase (LDH), glutathione (GSH), and superoxide dismutase (SOD) in myocardial tissues were determined. Immunofluorescence analysis of translocase of outer mitochondrial membrane 20 (TOMM20) was performed to observe the pathological changes in myocardial tissues. The protein expressions of AMPK, p-AMPK, p38, p-p38, Nrf2, and heme oxygenase 1 (HO-1) were determined by western blotting. Results: Compared with the sham group, the expressions of AMPK, p38, Nrf2, and HO-1 in the myocardium were significantly increased in the MI/R group. Compared with the MI/R group, the RSV + MI/R group had a significantly lower oxidative stress level, milder myocardial injury, increased expressions of AMPK, Nrf2, and HO-1, and lower expression of p38. The protein expressions of Nrf2 and HO-1 were partially inhibited in the RSV + C + MI/R group. Conclusions: Resveratrol can inhibit oxidative stress and alleviate MIRI by activating the AMPK/p38/Nrf2 signaling pathway. Meanwhile, AMPK/p38/Nrf2 is also an endogenous antioxidant stress pathway that protects against stress.
ABSTRACT
Correlated spectroscopic analysis can provide complementary chemical insights that are often unattainable by either approach used in isolation. We distinguished the different self-assembling behavior of isomeric aminothiophenols (ATPs) on Ag dendrite by the correlation of surface-enhanced Raman spectroscopy and laser-induced desorption ionization mass spectrometry, demonstrating that steric effect impinged significantly upon surface molecular density and plasmon-driven catalytic reaction yield, which led to drastic variations in the resulting SERS spectra. The correlative measurement shows that ortho-substitute barely formed a self-assemble monolayer, relative to the para-isomer, which can form a close-packed self-assembled monolayer and perform a decent azo-coupling reaction. Comparison between normal and SERS spectra of ATP isomers supports the fact that additional disulfide- or hydrogen-bonding interactions are established in para-ATP solid crystal, but neither of ortho- nor meta-isomers. This work is expected to create a significant impact on the development of an orthogonally correlated spectroscopic tool in deciphering chemical insights and underlying reaction mechanism. Graphical abstract.
