卧式搅拌釜气液流动数值模拟及多目标参数优化

采用双欧拉模型、SST k-ω湍流模型和多重参考系法对搅拌釜内气液两相流动行为进行数值模拟。结果表明:在所有影响因素中,转速对搅拌釜性能的影响最大,其次是挡板宽度。通过正交试验和矩阵分析,发现最优工况为桨叶离底高度950 mm、桨叶间距1300 mm、挡板宽度525 mm和转速123 r/min。在优化工况下,保证气含率和相对功耗基本不变时,混匀时间从31.620 s缩短至25.845 s。

卧式搅拌釜气液两相流场的参数化研究

基于Fluent软件,采用SST k−ω湍流模型、欧拉−欧拉两相流模型和多重参考系法对卧式搅拌釜气液两相流场进行数值模拟,并采用示踪剂法研究釜内混合过程。结果表明:增大转速或气体流量有利于气相分布更均匀并加快液相的混合。当搅拌转速超过93 r/min时,相对功率消耗基本不变。上叶轮倾斜角的变化对气相分布的影响很小。当倾角为50°时,相对功率消耗最大。适当提高桨叶离底高度可以提高气含率并改善气相分布,但会增加液相混匀时间。

Influence of simvastatin on dopaminergic neurons of lipopolysaccharide—induced rat model of Parkinson's disease

Objective::To investigate the neuroprotective effects of simvastatin on lipopolysaccharide(LPS)-indueed rat model of Parkinson's disease(PD) and the mechanisms involved.Methods:Hemiparkinsonian rat models were induced by stereotaxieal injection of LPS in the right substantia nigra compacts.After 2 weeks of simvastatin treatment,rotational behavior test was performed after the intraperitoneal injection of apomorphine.Expression of tyroxine hydroxylase(TH) and glial fibrillan acidic protein were analyzed through immunohistochemical staining of substantia nigra and striatum,and the level of TNF-α was evaluated using enzyme-linked immunosorbent assay.Results:Comparing with untreated group,behavioral symptoms of the rats were significantly less in the rats that received simvastatin treatment.The TH positive cell count in substantia nigra and striatum were significantly increased(P<0.05) and TNF- α expression was significantly decreased(P<0.05) in simvastatin group compared to untreated group.Conclusions:Simvastatin could effectively inhibit the activation of astrocytes,reduce TNF-α expression,and exert anti-inflammatory effects,and thus protect the dopaminergic neurons in substantia nigra and striatum of the rat model of PD.

Numerical analysis of supersonic jet flow and dust transport induced by air ingress in a fusion reactor

During a loss of vacuum accident(LOVA),the air ingress into a vacuum vessel(VV)may lead to radioactive dust resuspension,migration,and even explosion,thereby posing a great threat to the safe operation of future fusion reactors;thus,it is crucial to understand the flow characteristics and radioactive dust transport behavior induced by LOVA.However,only a few studies have identified the characteristics of the highly under-expanded jet flow at a scale of milliseconds during LOVA.Particularly,the occurrence and behavior of a Mach disk is yet to be captured in existing studies.In this study,we used a more advanced model with a finer mesh and adaptive mesh strategies to capture the Mach disk in a VV during LOVA.In detail,a computational fluid dynamics–discrete phase model one-way coupled multiphase approach was established using the computational fluid dynamics code ANSYS FLUENT and applied to the analysis during the first seconds of LOVA.The results showed that air ingress into the VV behaved like a highly free under-expanded jet at the initial stage and Mach disk was formed at~6 ms.Moreover,the flow field dramatically changed at the position of the Mach disk.The jet core before the Mach disk had a maximum velocity of~8 Mach with the corresponding lowest static pressure(~100 Pa)and temperature(few tens of K).The friction velocities in the lower part of the VV,which is an area of concern due to dust deposition,were generally larger than 15 m/s near the inlet region.Lastly,the crude prediction of the particle trajectories demonstrated the spiral trajectories of the dust following the air motion.Therefore,this study provided a basis for further safety analysis and accident prevention related to dust transport and explosion in future fusion reactors.

Research progress on the correlation between ion channel and excitability of striatum neurons in Parkinson's disease

Parkinson's disease(PD)is a neurodegenerative disorder due to gradual loss of dopaminergic neurons in the substantia nigra in the midbrain,however the pathogenesis is unclear.There is a correlation between the excitability of striatal neurons and PD.Ion channels are important to maintain membrane potential and regulate excitability of neurons,while ionic mechanisms for modulation of neurons excitability are not fully understood.This article reviews the relationship between ion channels and excitability of striatal neurons in PD and ion channel changes in the pathogenesis of PD.In order to find new targets to treatment PD by intervening ion channels.

Meta-analysis of efficacy and safety of Donepezil in treating cognitive decline of Parkinson's disease

Objective:To systematically evaluate the efficacy and safety of Donepezil in treating the cognitive decline in patients with Parkinson's disease(PD).Methods:Nine literature databases in domestic and abroad were searched by computer,and the search deadline was November 2,2020.The randomized controlled trials(RCT)using donepezil to treat the cognitive decline in patients with PD were screened.The MMSE(Mini-Mental State Exam)scores,MoCA(Montreal Cognitive Assessment)scores and adverse events of the included RCTs were extracted.Meta-analysis was implemented with RevMan 5.3 software,and the subgroup analyses were conducted to evaluate the effects of mean age and mean course of disease on the MMSE scores.Results:14 RCTs with 1263 patients were selected,including 646 cases in the experimental group and 617 cases in the control group.There were 1209 effective patients who completed MMSE score,including 612 in the experimental group and 597 in the control group.Meta-analysis results showed that MMSE scores in the experimental group were higher than that in the control group after using donepezil intervention,and the difference was statistically significant[SMD=0.55,95%CI(0.24,0.87),P=0.0006].It was also found that the MoCA scores of experimental group were higher than that of control group after using donepezil intervention,and the difference was statistically significant[SMD=1.25,95%CI(0.79,1.72),P<0.00001].Subgroup analysis showed that donepezil improved MMSE scores in different subgroups,and the difference between each group was statistically significant.There was no heterogeneity in the subgroup of mean age lower than 65 years,and the heterogeneity existed between the subgroup of mean course of disease lower than 3 years and the subgroup of mean course of disease larger than or equal to 3 years.For adverse events,the incidence of adverse events in the experimental group was 22.18%.There was no heterogeneity between the included studies(I2=0%),and the difference was not statistically significant[RR=1.18,95%CI(0.95,1.47),P=0.14].Conclusion:The results of meta-analysis showed that donepezil can improve the cognitive decline in patients with Parkinson's disease significantly,and it has good safety.

THE BLOSSOM APPROACH TO THE DIMENSION OF THE BIVARIATE SPLINE SPACE

Presents information on a study which outlined the blossom approach to the dimension count of bivariate spline space. Smoothness conditions in blossoming form; Application of the approach to the case of Morgan-Scott partition.