CFD Simulation of a Supercritical CO2 Rolling Rotor Expander for Waste Heat Recovery System of Engines

The supercritical CO2 power cycle system for waste heat recovery (WHR) of internal combustion engine (ICE) has widely been concerned as a research hotspot. And the expander is a key component in the supercritical CO2 power system. Rolling rotor expander has the following advantages: compact size, light weight, less moving parts, high stability and long service life, which qualify it a very suitable choice for engine’s waste heat recovery system. For a self-designed rolling rotor expander using supercritical CO2 as its working fluid, FLUENT software was used to simulate its internal flow field in this study, obtaining the changes of the internal pressure field and turbulent kinetic energy. The causes of local vortex in the expansion process were analyzed. Under different working conditions of the expander, the change of internal pressure and the distribution of P-V curve were observed, and the work capacity under different inlet pressure was analyzed. Results show that, the work capacity increases if the intake pressure increases within a certain range. However, if the inlet pressure keeps increasing and exceeds a reasonable limit, the local vortex in the suction process is enhanced and the pressure loss is increased and the degree of the turbulence is strengthened, which causes a certain impact on the expansion process and expander service life. The rotating speed has a great influence on the operation of the expander. These results provide guidance for the design and optimization of the supercritical CO2 expander in the future

Negative Expression of DSG1 and DSG2, as Prognostic Biomarkers, Impacts on the Overall Survival in Patients with Extrahepatic Cholangiocarcinoma

Aims. To evaluate the expression of DSG1 and DSG2 and investigate their clinicopathological significance in EHCC. Method. The protein expression of DSG1 and DSG2 was measured by EnVision immunohistochemistry in 15 normal biliary tract tissues, 10 biliary tract adenoma tissues, 30 peritumoral tissues, and 100 EHCC tumour tissues. Result. The expression of the DSG1 and DSG2 proteins was significantly lower in EHCC tumour tissues than in normal biliary tract tissues, biliary tract adenoma, and peritumoral tissues (P<0.05). Adenoma and peritumoral tissues with negative DSG1 and/or DSG2 protein expression exhibited atypical hyperplasia. DSG1 expression was positively correlated with DSG2 expression in EHCC (P<0.01). In patients with good differentiation, no invasion, no lymph metastasis, TNM I + II stage, and radical surgery, the positive expression of DSG1 and DSG2 proteins was higher (P<0.05). In comparison to patients with negative DSG1 and/or DSG2 expression, the average overall survival time of those with positive expression was significantly longer (P=0.000). Cox multivariate analysis revealed that negative DSG1 and DSG2 expressions were independent of poor prognosis factors in EHCC patients. The AUC calculated for DSG1 was 0.681 (95% confidence interval: 0.594–0.768) and that for DSG2 was 0.645 (95% confidence interval: 0.555–0.734), while that for DSG1 and DSG2 was 0.772 (95% confidence interval: 0.609-0.936). Conclusions. Negative protein expression of DSG1 and DSG2 is closely related to the pathogenesis, severe clinicopathological characteristics, aggressive biological behaviours, and dismal prognosis in EHCC

Nonvolatile magnetization switching in a single-layer magnetic topological insulator

Abstract Magnetization in a ferromagnetic layer could be manipulated by the spin-orbit torque whose generation commonly relies on the spin-orbit coupling from the adjacent heavy-metal layer within the bilayer. The fact that the magnetic topological insulator possesses both the ferromagnetic order with perpendicular anisotropy and inherent spin-orbit coupling inspires to realize such a torque-induced magnetization switching without forming any heterostructure with other materials. Here, only using a single layer of magnetically-doped topological insulator Cr:(Bi,Sb)2Te3, we realize a magnetization switching only by applying a large dc current. Assisted by the magnetic history, such a switching behaves nonvolatile under zero field but becomes volatile otherwise, as consistently shown by magnetoelectric transports and magneto-optical Kerr effect measurements. Static and quasistatic current are found to be equivalent for the switching. We propose that this switching may associate with the torque resulted from the spin-orbit coupling and the compositional asymmetry in the Cr-profile of the single layer