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Objective To investigate the effect of pseudolaric acid B (PAB) on apoptosis of prostate cancer cell line DU145 and the potential mechanism. Methods The cells were treated with 0, 5, 10, 20 and 40 μmol/L PAB for 24, 48, 72 and 96 hours respectively;the CCK8 method was used to detect cell proliferation,flow cytometry annexin V-FITC/PI double staining and TUNEL method was used to detect cell apoptosis after the treatment of PAB. Scratch test and transwell chamber were used to detect cell migration and invasion. Western blot was used to detect the protein expressions of Bcl-2, Bax, PTEN, AKT and p-AKT in the cells. Results With the increase of PAB concentration and time of incubation, the cell viability of DU145 cells was significantly reduced (P＜0.01). Compared with the control group, the average cell apoptosis rate, Bax and PTEN protein expression in the PAB group were significantly increased, while the cell scratch healing rate, the number of transmembrane cells, Bcl-2 and p-AKT protein expression were significantly reduced(P＜0.01). GW9662 significantly reversed the pro-apoptotic effect of PAB on DU145. Conclusions PAB may inhibit the proliferation and invasion of prostate cancer DU145 cells and induce cell apoptosis through the PTEN/AKT signaling pathway.

Incremental learning has achieved good results in image classification,but it is challenging to apply incremental learning to multi-class object detection.Object detection is more complex than image classification,which combines classification and border regression.At present,the most advanced incremental object detectors adopt the external fixed region suggestion method based on knowledge distillation,which consumes a lot of time and cost.For single-stage detectors,due to the lack of annotation and region advice information for the old class,old objects are usually identified by the detector as the background,resulting in catastrophic forgetting.In this paper,a label selection algorithm based on border distance metric is proposed.It uses the detection results of the old model and the existing dataset labels to select and merge by measuring the coincidence of the bounding boxes,making up for the lack of annotations of the old objects in the new dataset and alleviating catastrophic forgetting.In addition,a module that combines the attention module with the residual module is designed to extract discriminative features at different depths in feature extraction network,to further improve the detection accuracy of model.The proposed method is implemented in the single-stage detection framework,and the effectiveness of the method is verified on PASCAL VOC dataset.Compared with the best model at present,the average accuracy value of the old object and all objects improves by 2.8% and 2.1%,respectively.The pseudo-labels obtained by the proposed method greatly alleviate the forgetting problem,and the attention residual module improves the detection accuracy of the model.

Due to the existence of the associated gas, the spiral weld of a pipeline in Tahe Oilfield was cracked.In order to clarify the failure reason of spiral weld of the pipeline and provide effective guidance for future pipeline corrosion control, the macro morphology of the cracked part of the spiral weld of the associated gas pipeline, the part far away from the weld and the material surface at both ends of the defect were observed, respectively.The composition of material was analyzed by fluorescence spectrometer.The micro morphology and element components of the cracked part were observed and analyzed by scanning electron microscope and X-ray energy dispersive spectrum, and the cracking reason of the spiral weld of the associated gas pipeline were analyzed.Results showed that the fracture of the associated gas pipeline was the result of hydrogen induced cracking(HIC)and sulfide stress corrosion cracking(SSCC)caused by high content of H2S in the associated gas in the pipeline.The middle of the fissure(i.e.the widest part)was the starting point of the crack.

In order to solve the problem of acid corrosion in crude oil extraction, two double condensed Schiff base corrosion inhibitors XFJ - 1 and XFJ - 2 were synthesized by the solvent method. The corrosion inhibition performance at the environment of 90 ℃ and 15%(mass fraction) HCl was evaluated by static weightless method and polarization curve method, and the corrosion inhibition mechanism of XFJ - 1 and XFJ - 2 was explained by simulation method from the molecular level. Results showed that when the mass fraction of the two inhibition was 1.0%, respectively, the corrosion inhibition efficiency of the two corrosion inhibitors reached 82.90% and 99.46%, respectively, and simultaneously suppressed the cathodic and anodic reactions of N80 steel. The adsorption forms were consistent with the Langmuir adsorption isotherm model. The simulation results indicated that the corrosion inhibitor molecules would mainly accept or provide electrons through the benzene ring and the C=N double bond. The reactivity and adsorption energy of the XFJ - 2 corrosion inhibitor were greater than those of XFJ - 1, which was also consistent with the experimental data, indicating that the corrosion inhibition effect of XJF - 2 was better than that of XJF - 1.

It is still a challenge to achieve perfect ((near-unity)) absorption across a wide wavelength range with a three-layer structure. This paper presents a metamaterial absorber (MA) based on MXene that can achieve broadband and perfect absorption in the near-infrared and visible regions. The MA with a simple three-layer structure consists of a top Ti3C2Tx layer, an intermediate dielectric layer and a bottom gold layer. It can achieve perfect absorption (the absorptivity over 99%) in the wavelength range of 730–900 nm. The electric field distribution reveals that the localized surface plasmon resonance occurring at the interface of Ti3C2Tx and SiO2 leads to strong absorption over the wide wavelength range. Furthermore, the MA exhibits excellent angular stability. This work provides a method to construct MAs with broadband perfect absorption in the near-infrared and visible band. [ABSTRACT FROM AUTHOR]