Experimental Investigation on Cooling/Heating Characteristics of Ultra-Thin Micro Heat Pipe for Electric Vehicle Battery Thermal Management

Due to the heat pipes’ transient conduction,phase change and fluid dynamics during cooling/heating with high frequency charging/discharging of batteries,it is crucial to investigate in depth the experimental dynamic thermal characteristics in such complex heat transfer processes for more accurate thermal analysis and design of a BTMS. In this paper,the use of ultra?thin micro heat pipe(UMHP) for thermal management of a lithium?ion battery pack in EVs is explored by experiments to reveal the cooling/heating characteristics of the UMHP pack. The cooling performance is evaluated under di erent constant discharging and transient heat inputs conditions. And the heating e ciency is assessed under several sub?zero temperatures through heating films with/without UMHPs. Results show that the pro?posed UMHP BTMS with forced convection can keep the maximum temperature of the pack below 40 °C under 1 ~ 3 C discharging,and e ectively reduced the instant temperature increases and minimize the temperature fluctuation of the pack during transient federal urban driving schedule(FUDS) road conditions. Experimental data also indicate that heating films stuck on the fins of UMHPs brought about adequate high heating e ciency comparing with that stuck on the surface of cells under the same heating power,but has more convenient maintenance and less cost for the BTMS. The experimental dynamic temperature characteristics of UMHP which is found to be a high?e cient and low?energy consumption cooling/heating method for BTMSs,can be performed to guide thermal analysis and optimiza?tion of heat pipe BTMSs.

MicroRNAs in nasopharyngeal carcinoma

MicroRNAs(miRNAs) provide insight into both the biology and clinical behavior of many human cancers, including nasopharyngeal carcinoma(NPC). The dysregulation of miRNAs in NPC results in a variety of tumor-promoting effects. Furthermore, several miRNAs are prognostic markers for NPC. In addition to cellular miRNAs, NPC samples also often contain miRNAs encoded by Epstein-Barr virus, and these miRNAs may impact NPC biology by targeting both cellular and viral genes. Given their numerous putative roles in NPC development and progression, a thorough understanding of the impact of miRNA dysregulation in NPC is expected to shed light on useful biomarkers and therapeutic targets for the clinical management of this disease. In this review, we describe the efforts to date to identify and characterize such miRNAs in the context of NPC.

Study on the influence of projectile on muzzle disturbance

In order to make an efficient analysis of muzzle disturbance influenced by projectile mass, mass eccentricity, dynamic unbalance, load deviation, and clearance between projectile and bore, the orthogonal test method is extended to analyze the launch dynamics. Taking a tank as the research object, the launch dynamics equations of a tank system are established. Based on the stochastic simulation principle, the tank launch dynamic simulation system is constructed and through the development of the orthogonal test method, the influence of projectile on muzzle disturbance is studied. The study results provided both theoretical foundation and simulation approaches for improving the firing dispersion of the tank.

Magnesium-L-threonate exhibited a neuroprotective effect against oxidative stress damage in HT22 cells and Alzheimer’s disease mouse model

BACKGROUND Oxidative stress results in the production of excess reactive oxygen species(ROS)and triggers hippocampal neuronal damage as well as occupies a key role in the pathological mechanisms of neurodegenerative disorders such as Alzheimer’s disease(AD).A recent study confirmed that magnesium had an inhibitory effect against oxidative stress-related malondialdehyde in vitro.However,whether Magnesium-L-threonate(MgT)is capable of suppressing oxidative stress damage in amyloidβ(Aβ)_(25-35)-treated HT22 cells and the AD mouse model still remains to be investigated.AIM To explore the neuroprotective effect of MgT against oxidative stress injury in vitro and in vivo,and investigate the mechanism.METHODS Aβ_(25-35)-induced HT22 cells were preconditioned with MgT for 12 h.APPswe/PS1dE9(APP/PS1)mice were orally administered with MgT daily for 3 mo.After MgT treatment,the viability of Aβ_(25-35)-treated HT22 cells was determined via conducting cell counting kit-8 test and the cognition of APP/PS1 mice was measured through the Morris Water Maze.Flow cytometry experiments were applied to assess the ROS levels of HT22 cells and measure the apoptosis rate of HT22 cells or hippocampal neurons.Expression of B-cell lymphoma 2(Bcl-2),Bcl-2-associated X(Bax),hypoxiainducible factor(HIF)-1α,NADPH oxidase(NOX)4,Aβ_(1-42) and phosphatidylinositol-3-kinase(PI3K)/protein kinase B(Akt)pathway proteins was quantified by Western blot.RESULTS In vitro data confirmed that Aβ_(25-35)-induced HT22 cells had a significantly lower cell viability,higher ROS level and higher apoptosis rates compared with those of control cells(all P<0.001).MgT prevented the Aβ_(25-35)-triggered oxidative stress damage by elevating viability and decreasing ROS formation and apoptosis of HT22 cells(all P<0.001).APP/PS1 mice exhibited worse cognitive performance and higher apoptosis rate of hippocampal neurons than wild-type(WT)mice(all P<0.01).Meanwhile,significant higher expression of Aβ_(1-42) and NOX4 proteins was detected in APP/PS1 mice than those of WT mice(both P<0.01).MgT also ameliorated the cognitive deficit,suppressed the apoptosis of hippocampal neuron and downregulated the expression of Aβ_(1-42) and NOX4 proteins in APP/PS1 mouse(all P<0.05).Moreover,MgT intervention significantly downregulated HIF-1αand Bax,upregulated Bcl-2 and activated the PI3K/Akt pathway both in vitro and in vivo(all P<0.05).CONCLUSION MgT exhibits neuroprotective effects against oxidative stress and hippocampal neuronal apoptosis in Aβ_(25-35)-treated HT22 cells and APP/PS1 mice.

Modeling and simulation of neodymium oxide dissolution in molten fluorides

By combining the mass transfer mechanism of neodymium oxide with dissolution kinetics,a solution strategy for neodymium oxide dissolution was proposed to predict the dissolved neodymium oxide concentration during the process under complex flow field conditions.The factors affecting neodymium oxide dissolution were analyzed in detail.Aiming at the pulse feeding and continuous feeding modes in industrial practice,the characteristics of the dissolution process under the two feeding modes were compared.Simulation results showed that pulse feeding took shorter time to distribute evenly than continuous feeding.Finally,the dissolution time of single-particle neodymium oxide under static flow field conditions was compared with the literature results.Except for only one set of data with a maximum error of about 10%,the errors of other data are all within 5%.

Prevention of central venous catheter-related infection in ICU with cluster nursing intervention: a meta-analysis

Objective:To systematically evaluate the clinical effects of cluster nursing intervention in preventing central venous catheter-related infection in intensive care unit.Methods:A randomized controlled study was searched from China National Knowledge Internet(CNKI),Wanfang,Chinese Scientific Journals Database(VIP),Chinese Biomedical Literature Service System(SinoMed),PubMed,Embase and Cochrane library databases from the establishment to May 1,2020.Two reviewers independently evaluated and cross checked the quality of the study.Revman 5.3 was used to conduct the meta-analysis.Results:A total of 21 randomized controlled trials with 6,030 patients were included.Meta-analysis showed that the incidence of central venous catheter-related infection(relative risk(RR)=0.29,95%confidence interval(CI)[0.23,0.37]),the incidence of catheter plugging(RR=0.25,95%CI[0.16,0.39])and catheter prolapse(RR=0.18,95%CI[0.11,0.29])were significantly different between the two groups.Conclusion:Cluster nursing intervention could prevent central venous catheter-related infection in intensive care unit.

仿生纳米通道的制备、修饰及生物分析应用

纳流控作为一种新兴技术,近年来得到了广泛关注.其产生和发展伴随着新流体现象的发现和新型器件的诞生.纳米流体中独特的物质传输性质和潜在的应用引起了广泛关注.迄今为止,纳米通道器件在DNA测序、单分子传感、能源储存与转换、离子门控等方面显示出了巨大的应用前景.本文总结了仿生纳米通道的设计与制备、纳米通道功能化修饰的策略及其在生物分析中的应用研究,并思考了仿生纳米通道的发展与面临的挑战.

ECG quality assessment based on a kernel support vector machine and genetic algorithm with a feature matrix

We propose a systematic ECG quality classification method based on a kernel support vector machine(KSVM) and genetic algorithm(GA) to determine whether ECGs collected via mobile phone are acceptable or not. This method includes mainly three modules, i.e., lead-fall detection, feature extraction, and intelligent classification. First, lead-fall detection is executed to make the initial classification. Then the power spectrum, baseline drifts, amplitude difference, and other time-domain features for ECGs are analyzed and quantified to form the feature matrix. Finally, the feature matrix is assessed using KSVM and GA to determine the ECG quality classification results. A Gaussian radial basis function(GRBF) is employed as the kernel function of KSVM and its performance is compared with that of the Mexican hat wavelet function(MHWF). GA is used to determine the optimal parameters of the KSVM classifier and its performance is compared with that of the grid search(GS) method. The performance of the proposed method was tested on a database from PhysioNet/Computing in Cardiology Challenge 2011, which includes 1500 12-lead ECG recordings. True positive(TP), false positive(FP), and classification accuracy were used as the assessment indices. For training database set A(1000 recordings), the optimal results were obtained using the combination of lead-fall, GA, and GRBF methods, and the corresponding results were: TP 92.89%, FP 5.68%, and classification accuracy 94.00%. For test database set B(500 recordings), the optimal results were also obtained using the combination of lead-fall, GA, and GRBF methods, and the classification accuracy was 91.80%.

Electronic-property dependent interactions between tetracycline and graphene nanomaterials in aqueous solution

Understanding the interactions between graphene nanomaterials（GNMs） and antibiotics in aqueous solution is critical to both the engineering applications of GNMs and the assessment of their potential impact on the fate and transport of antibiotics in the aquatic environment. In this study, adsorption of one common antibiotic, tetracycline, by graphene oxide（GO） and reduced graphene oxide（RGO） was examined with multi-walled carbon nanotubes（MWCNTs） and graphite as comparison. The results showed that the tetracycline adsorption capacity by the four selected carbonaceous materials on the unit mass basis followed an order of GO ＆gt; RGO ＆gt; MWCNTs ＆gt; graphite. Upon normalization by surface area,graphite, RGO and MWCNTs had almost the same high tetracycline adsorption affinity while GO exhibited the lowest. We proposed π-electron-property dependent interaction mechanisms to explain the observed different adsorption behaviors. Density functional theory（DFT） calculations suggested that the oxygen-containing functional groups on GO surface reduced its π-electron-donating ability, and thus decreased the π-based interactions between tetracycline and GO surface. Comparison of adsorption efficiency at different p H indicated that electrostatic interaction also played an important role in tetracycline-GO interactions. Site energy analysis confirmed a highly heterogeneous distribution of the binding sites and strong tetracycline binding affinity of GO surface.