科创中国

Objective To detect the cell viability and the expressions of stem cell surface markers after chemotherapeutic drug treatment.Methods We observed the cytotoxic effects of three chemotherapeutic agents[epirubicin(Epi),fluorouracil(5-FU)and cyclophosphamide(Cyc)]in three cell lines,and the cell viabilities after removed these chemotherapeutic agents.Expressions of stem cell surface markers CD44,CD24,CD90,CD14 and aldehyde dehydrogenase1(ALDH1)in breast cancer cells were analyzed by real-time PCR.The post hoc analysis(Tukey's tests)in conjunction with one-way ANOVA was used for statistical analysis.Results The initial cytotoxic efficacy was most notable.After the treatment of the same therapeutic agents,cell viability was decreased by 64.8%35.14%,32.25%in BT-483 cells,66.4%,22.94%and 45.88%in MDA-MB-231 cells,97.1%,99.5%and 76.4%in MCF cells.The difference was significant compared with that before treatment(P=0.000).However,the inhibitory effects were diminished after chemotherapeutic agent withdrawal.Cell viabilities were increased to 167.9%,212.04%and 188.66%in MDA-MB-231 cells at48 h after withdrawal.At 72 h after withdrawal,cell viability was increased with a significant difference in three cell lines(all P values=0.000).Expressions of CD44 and ALDH1 were most prevalent for MDA-MB-231,BT-483 and MCF-7 cells.ALDH1 mRNA level was significant higher in BT-483(HER-2 overexpression cell line)than MDA-MB-231(triple negative cell line)(P=0.012).CD14 mRNA level in MCF-7 cells were significantly lower than that in MDA-MB-231 and BT-483(P=0.003,0.001).BT-483 showed significantly higher level of CD44 than MDA-MB-231 and MCF-7 cell line(P=0.013,0.020),and no significant difference was detected between MDA-MB-231 and MCF-7 breast cancer cells(P=0.955).CD90 mRNA expressions were detected in MDA-MB-231 cells and MCF-7 cells,but not in BT-483 cells.Conclusion Some malignant cells could survive in vitro and begin to proliferate again between cycles of chemotherapy.

In precision machining of complex curved surface parts with high performance, geometry accuracy is not the only constraint, but the performance should also be met. Performance of this kind of parts is closely related to the geometrical and physical parameters, so the final actual size and shape are affected by multiple source constraints, such as geometry, physics, and performance. These parts are rather difficult to be manufactured and new manufacturing method according to performance requirement is urgently needed. Based on performance and manufacturing requirements for complex curved surface parts, a new classification method is proposed, which divided the complex curved surface parts into two categories: surface re-design complex curved surface parts with multi-source constraints(PRCS) and surface unique complex curved surface parts with pure geometric constraints(PUCS). A correlation model is constructed between the performance and multi-source constraints for PRCS, which reveals the correlation between the performance and multi-source constraints. A re-design method is also developed. Through solving the correlation model of the typical part's performance-associated surface, the mapping relation between the performance-associated surface and the related removal amount is obtained. The explicit correlation model and the method for the corresponding related removal amount of the performance-associated surface are built based on the classification of surface re-design complex curved surface parts with multi-source constraints. Research results have been used in the actual processing of the typical parts such as radome, common bottom components, nozzle, et al., which shows improved efficiency and accuracy of the precision machining for the surface re-design parts with complex curved surface.

报告1例透明细胞汗腺瘤.患者女,22岁.3年前无意中发现左下腹一核桃大褐色半透明状实性肿块,逐渐增大,现约3.2cm*1.6cm*1.3cm,有蒂,表面光滑,质地中等,无压痛感.

As the two most important indexes of bearing raceway,surface roughness and roundness have significant influence on bearing noise.Some researchers have carried out studies in this field,however,reason and extent of the influence of raceway surface geometric characteristics on bearing running noise are not perfectly clear up to now.In this paper,the raceway of 6309 type bearing's inner and outer ring is machined by floating abrasive polishing adopting soft abrasive pad.Surface roughness parameters,arithmetical mean deviation of the profile Ra,the point height of irregularities Rz,maximum height of the profile Rmax and roundness f of raceways,are measured before and after machining,and the change rules of the measured results are studied.The study results show that the floating abrasive polishing can reduce the surface geometric errors of bearing raceway evidently.The roundness error is reduced by 25%,Rmax value is reduced by 35.5%,Rz value is reduced by 22%and Ra value is reduced by 5%.By analyzing the change of the geometrical parameters and the shape difference of the raceway before and after machining,it is found that the floating abrasive polishing method can affect the roundness error mainly by modifying the local deviation of the raceway's surface profile.Bearings with different raceway surface geometrical parameter value are assembled and the running noise is tested.The test results show that Ra has a little,Rmax and Rz have a measurable,and the roundness error has a significant influence on the running noise.From the viewpoint of controlling bearings'running noise,raceway roundness error should be strictly controlled,and for the surface roughness parameters,Rmax and Rz should be mainly controlled.This paper proposes an effective method to obtain the low noise bearing by machining the raceway with floating abrasive polishing after super finishing.

目的利用AAV介导的体细胞基因敲除技术,在人大肠癌细胞系HCTll6中对靶基因Sirt1进行敲除,达到基因沉默的目的.方法构建Sirtl打靶载体,通过病毒包装、感染、药物筛选、PCR鉴定、Westernblotting鉴定等步骤获得Sirt1基因敲除的细胞株.结果经过筛选和鉴定后获得两个Sirtl-/-阳性克隆,成功构建HCTll6Sirtl.一细胞系.结论通过体细胞敲除技术,我们成功地获得Sirtl敲除肠癌细胞株.

During hard cutting process there is severe thermodynamic coupling effect between cutting tool and workpiece, which causes quenching effect on finished surfaces under certain conditions. However, material phase transformation mechanism of heat treatment in cutting process is different from the one in traditional process, which leads to changes of the formation mechanism of damaged layer on machined workpiece surface. This paper researches on the generation mechanism of damaged layer on machined surface in the process of PCBN tool hard cutting hardened steel Cr12 Mo V. Rules of temperature change on machined surface and subsurface are got by means of finite element simulation. In phase transformation temperature experiments rapid transformation instrument is employed, and the effect of quenching under cutting conditions on generation of damaged layer is revealed. Based on that, the phase transformation points of temperature under cutting conditions are determined. By experiment, the effects of cutting speed and tool wear on white layer thickness in damaged layer are revealed. The temperature distribution law of third deformation zone is got by establishing the numerical prediction model, and thickness of white layer in damaged layer is predicted, taking the tool wear effect into consideration. The experimental results show that the model prediction is accurate, and the establishment of prediction model provides a reference for wise selection of parameters in precise hard cutting process. For the machining process with high demanding on surface integrity, the generation of damaged layer on machined surface can be controlled precisely by using the prediction model.

近年来178Hfm2 31年的同核异能态被认为是用低能X射线触发使其释放储存能量的最合适候选者.为了探讨在178Hf中是否存在触发Kπ=16+同核异能态γ发射的门态,本工作首先用投影壳模型对178Hf的多准粒子态和集体激发态进行了研究,结果表明其它态位于距离16+同核异能态较远的地方.但当用包括γ自由度的组态限制(绝热阻塞)方法计算178Hf的多准粒子激发态时,结果显示有三个能级可能是16+同核异能态光退激的候选者,位能面计算的结果显示178Hf为轴对称硬核.

With the increasing noise pollution,low noise optimization of centrifugal pimps has become a hot topic.However,experimental study on this problem is unacceptable for industrial applications due to unsustainable cost.A hybrid method that couples computational fluid dynamics(CFD)with computational aeroacoustic software is used to predict the flow-induced noise of pumps in order to minimize the noise of centrifugal pumps in actual projects.Under Langthjem's assumption that the blade surface pressure is the main flow-induced acoustic source in centrifugal pumps,the blade surface pressure pulsation is considered in terms of the acoustical sources and simulated using CFX software.The pressure pulsation and noise distribution in the near-cutoff region are examined for the blade-passing frequency(BPF)noise,and the sound pressure level(SPL)reached peaks near the cutoff that corresponded with the pressure pulsation in this region.An experiment is performed to validate this prediction.Four hydrophones are fixed to the inlet and outlet ports of the test pump to measure the flow-induced noise from the four-port model.The simulation results for the noise are analyzed and compared with the experimental results.The variation in the calculated noise with changes in the flow agreed well with the experimental results.When the flow rate was increased,the SPL first decreased and reached the minimum near the best efficient point(BEP);it then increased when the flow rate was further increased.The numerical and experimental results confirmed that the BPF noise generated by a blade-rotating dipole roughly reflects the acoustic features of centrifugal pumps.The noise simulation method in current study has a good feasibility and suitability,which could be adopted in engineering design to predict and optimize the hydroacoustic behavior of centrifugal pumps.

The thin-walled tube flexure(TWTF) hinges have important potential application value in the deployment mechanisms of satellite and solar array, but the optimal design of the TWTF hinges haven't been completely solved, which restricts their applications. An optimal design method for the qusai-static folding and deploying of TWTF hinges with double slots is presented based on the response surface theory. Firstly, the full factorial method is employed to design of the experiments. Then, the finite element models of the TWTF hinges with double slots are constructed to simulate the qusai-static folding and deploying non-linear analysis. What's more, the mathematical model of the TWTF flexure hinge quasi-static folding and deploying properties are derived by the response surface method. Considering of small mass and high stability, the peak moment of quasi-static folding and deploying as well as the lightless are set as the objectives to get the optimal performances. The relative errors of the objectives between the optimal design results and the FE analysis results are less than 7%, which demonstrates the precision of the surrogate models. Lastly, the parameter study shows that both the slots length and the slots width both have significant effects to the peak moment of quasi-static folding and deploying of TWTF hinges with double slots. However, the maximum Mises stress of quasi-static folding is more sensitive to the slots length than the slots width. The proposed research can be applied to optimize other thin-walled flexure hinges under quasi-static folding and deploying, which is of great importance to design of flexure hinges with high stability and low stress.