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Background: An anomalous origin of the right coronary artery from the left coronary artery sinus is usually characterized by an acute take-off angle. Most affected patients have no clinical symptoms; however, some patients have decreased blood flow into the right coronary artery during exercise, which can lead to symptoms such as myocardial ischemia. Most researchers who have studied an anomalous origin of the right coronary artery from the left coronary artery sinus have done so through clinical cases. In this study, we used numerical simulation to evaluate the hemodynamics of this condition and the effect of an acute take-off angle on hemodynamic parameters. We expect that the results of this study will help in further understanding the clinical symptoms of this anomaly and the hemodynamic impact of an acute take-off angle.Methods: Three-dimensional models were reconstructed based on the computed tomography images from 16 patients with a normal right coronary artery and 26 patients with an anomalous origin of the right coronary artery from the left coronary artery sinus. A numerical simulation of a two-way fluid-structure interaction was executed with ANSYS Workbench software. The blood was assumed to be an incompressible Newtonian fluid, and the vessel was assumed to be an isotropic, linear elastic material. Hemodynamic parameters and the effect of an acute take-off angle were statistically analyzed.Results: During the systolic period, the wall pressure in the right coronary artery was significantly reduced in patients with an anomalous origin of the right coronary artery (t =1.32 s, P=0.0001; t =1.34-1.46 s, P<0.0001). The wall shear stress in the abnormal group was higher at the beginning of the systolic period (t =1.24 s, P=0.0473; t =1.26 s, P=0.0193; t =1.28 s, P=0.0441). The acute take-off angle was smaller in patients with clinical symptoms (27.81°±4.406°) than in patients without clinical symptoms (31.86°±2.789°; P=0.017). In the symptomatic group, pressure was negatively correlated with the acute take-off angle (P=0.0185-0.0341, r=−0.459 to −0.4167). Conclusions:This study shows that an anomalous origin of the right coronary artery from the left coronary artery sinus causes changes in hemodynamic parameters, and that an acute take-off angle in patients with this anomaly is associated with terminal ischemia of the right coronary artery.

Hydrophobic titanium oxide (TiO 2 ) film formed on metallic titanium substrate in hydrogen peroxide solution with a subsequent oxidation under air atmosphere. Component, microstructure, and hydrophobicity of the oxide film were characterized by X-ray diffraction, scanning electron microscope, and water contact angle methods. Corrosion resistance tests were carried out in seawater solution at different heating temperature conditions. Electrochemical impedance spectroscopy techniques and polarization curves were used to study the changes and the corrosion resistance of the TiO 2 film. The results demonstrate that the pre-treated TiO 2 film heated at 400 8C environment owns small special groove-shaped structure on its surface, which induce higher hydrophobic capability, larger impedance, and better electrochemical stability than the film that was prepared at other temperatures or the Ti with nature formed oxidation film. It would be an ideal candidate as engineering material in deep seawater environment.

To reduce frequent heavy air pollution, the Chinese government suspends clinker production during the heating season in most areas of the North, which is known as the Clinker Off-peak Production Policy. The questions regarding such a repressive production policy for environmental purposes are whether this policy is effective in reducing pollutants and whether the marginal cost is high. To explore these policy effects, a quasi-experiment is designed, taking advantage of spatial-temporal variations in policy implementation. With the triple-difference method and environmental satellite data, the effect on air pollution is estimated to be −1900 μg/m2 (~2%) of SO2 and −3200 μg/m2 (~10%) of NO2. With daily price information and the difference-in-differences method, the market effect is estimated to be an approximately 10% increase in annual sale prices. The marginal cost estimated through a back-of-the-envelope analysis is 32 k RMB yuan/ton SO2 or NO2, which is 24.88 times the pollutant discharge fee but which better reflects the pollutant shadow price.

Background: The anomalous origin of the right coronary artery (RCA) from the left coronary artery sinus (AORL) is one of the abnormal origins of the coronary arteries. Most of these issues rarely have any effects on human health, but some individuals may exhibit symptoms, such as myocardial ischemia or even sudden death. Recently, researchers have investigated the AORL through clinical cases, but studies based on computational fluid dynamics (CFD) have rarely been reported. In this study, the hemodynamic changes between the normal origin of the RCA and the AORL are compared based on numerical simulation results. Methods: Realistic three-dimensional (3D) models of the 16 normal right coronary arteries and 26 abnormal origins of the RCAs were constructed, respectively. The blood flow was numerically simulated using the ANSYS software. This study used a one-way fluid-solid coupling finite element model, wherein the blood is assumed to be an incompressible Newtonian fluid, and the vessel is assumed to be made of an isotropic linear elastic material. Results: The cross-sectional area differences between the inlet of the normal group and that of the abnormal group were significant (P < 0.0001). Moreover, there were significant differences in the volumetric flow (P = 0.0001) and pressure (P = 0.0002). Positive correlation exists for the ratio of the cross-sectional area of the RCA to the inlet area of the ascending aorta (AAO), and the ratio of the inlet volumetric flow of the RCA to the volumetric flow of the AAO, in the normal (P = 0.0001, r = 0.8178) and abnormal (P = 0.0033, r = 0.6107) groups. Conclusion: This study demonstrates that the cross-sectional area of the AORL inlet may cause ischemia symptoms. The results obtained by this study may contribute to the further understanding of the clinical symptoms of the AORL based on the hemodynamics.

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