Objective Our objective was to compare the effectiveness of nonbiological artificial liver (NBAL) support, particularly short-term (28-day) survival rates, in patients who underwent treatment using double plasma molecular adsorption system (DPMAS), plasma exchange (PE), or combined PE+DPMAS, in addition to comprehensive physical treatment for different stages of acute-on-chronic liver failure (ACLF). Methods We retrospectively reviewed clinical data of 135 patients with ACLF who received NBAL treatment between November 2015 and February 2019. The patients were categorized into PE, DPMAS, and PE+DPMAS groups. Short-term effectiveness of treatment was assessed and compared based on selected clinical findings, laboratory parameters, and liver function markers. Results Coagulation function improved significantly in all groups after treatment. In the PE and PE+DPMAS groups, prothrombin time decreased to different degrees, whereas plasma thromboplastin antecedent increased significantly after treatment. White blood cell counts increased and platelet counts decreased in all groups after treatment. The model for end-stage liver disease score, Child–Pugh grade, systematic inflammatory syndrome score, and sepsis-related organ failure score decreased in all three groups after treatment. Conclusions PE, DPMAS, and PE+DPMAS improved disease indicators in all patients with ACLF. The combined treatment improved the short-term effectiveness of treatment, especially in patients with mild ACLF.
In spite of much progress in the development of gasoline direct injection (GDI) engines, choosing an appropriate piston top contour to obtain desirable combustion efficiency is still an arduous process for engineers. This study investigates the combined effects of piston bowl geometry and a charge motion control valve (CMCV) on tumble flow and combustion features in GDI engines. Based on the model validation, the processes of intake, spray, mixture formation and combustion at different engine speeds are simulated and analyzed for different piston shapes for the two cases of opening and closing the CMCV. The results show that the bowl on the top of piston is beneficial for the formation and development of tumble flow. The flat top piston with the CMCV closed is able to achieve acceptable combustion pressure. However, with the increase of engine speed and load, the advantages of the flat top pistons gradually disappear; the dual offset bowl piston has a minimum tumble ratio and turbulence kinetic energy (TKE) at the end of the compression stroke because of the projection in the middle of the piston top surface which leads to a lower pressure rise rate and a reduced flame propagation speed at high load. The closed CMCV contributes to a faster evaporation rate and a more uniform mixture at lower speeds. It is not recommended for use at high speeds due to lower intake air mass and reduced combustion pressure. The research provides an effective way for engineers to choose an appropriate piston top contour combined with a CMCV to obtain desirable combustion efficiency.
ARTICLE HISTORY
Ultrasonic oil production technique for enhanced oil recovery (EOR) attracts more attention due to its high adaptability, simple operation, low cost and zero pollution to the oil reservoir. In this paper, recent new downhole tools used for enhanced oil recovery developed in China are summarized. Furthermore, research advance on some key problems that affect the widespread application of ultrasonic oil production technique in China are also summarized in view of what are the primary factors that influence crude oil paraffin inhibition and viscosity reduction, whether ultrasonic excitation is better than chemical agent for any plugs removal and whether ultrasound-chemical combination plug removal technology has the best plugs removal effect. The purpose of this paper is to provide reference for the broad application of ultrasonic oil production for enhance oil recovery.
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