Characteristics of shock wave as well as its evolution of aluminum plasma produced by nanosecond YAG laser is investigated by time-resolved optical shadowgraph images. Experimental results show that shock wave is strongly influenced by the laser parameters and target arrangement. Shock waves from aluminum plasma and air plasma are observed simultaneously by shadowgraphs when the distance from lens to target surface (DLTS) is longer than the lens focal length, and a narrow bright "line" is observed in the region where shock waves from Al plasma and air plasma meet. The longitudinal expansion velocity of shock wave from Al plasma is largely influenced by DLTS and laser intensity as well, and it increases with laser intensity at the early stage of plasma expansion and reach to a maximum of 8.1×104 m/s.
Estimating the 6D pose of known objects is an important task for many robotic and AR applications. The most recent trend in 6D pose estimation has been to take advantage of deep networks to either directly regress the pose from the image or to first predict the 2D locations of 3D keypoints and then recover the pose according to the 2D-3D coordinates relationship of keypoints using a PnP algorithm. However, most of these methods are vulnerable to occlusions. In this paper, we present a simple but efficient method to estimate 6D pose of objects using anchor-based corner detection, based on two-stage detection backbone (i.e. Faster R-CNN Ren et al. (2015)). Instead of directly predicting two-dimensional coordinates of the projected 3D bounding box (i.e. corners), we regress relative coordinates of top corners based on the two-dimensional anchor and diagonals of corresponding faces. Bottom corners are further robustly inferred using geometrical constraints of face diagonals. Experiments show that our method achieves significant improvement on LineMod S. Hinterstoisser et al. (2012) and Occlusion Brachmann et al. (2014a) dataset, outperforming most existing 6D pose estimation methods without using refinement.
In this study, experiments were designed to investigate the effects of oxidized low density lipoprotein (ox‐LDL) on bone marrow stem cell differentiation into endothelial cells and underlying mechanisms. Adult rat bone marrow multipotent progenitor cells (MAPCs) were used as the source of stem cells, and induced to differentiate into endothelial cells with or without ox‐LDL in the presence of VEGF. The differentiation process was closely monitored with cell morphology and expressions of endothelial markers including vWF, Flk‐1, and CD31 with RT‐PCR and Western blot analysis. As expected, the differentiating stem cells started to express vWF, Flk‐1, and CD31 from day 5 of differentiation, and reached their maximum at day 14. Ox‐LDL (at 9, 18, and 36 ug/ml) significantly inhibited the differentiation of MAPCs into endothelial cells in a dose‐dependent manner (p < 0.05) as reflected by markedly decreased mRNA levels and contents of vWF, Flk‐1, and CD31. Interestedly, the decreased expressions of endothelial markers were associated with significantly reduced Akt phosphorylation during the early phase of differentiation in these cells. These results indicate that ox‐LDL inhibits the differentiation of bone marrow stem cells into endothelial cells possibly through preventing Akt phosphorylation. The data from this study provides a novel mechanism for the development of ox‐LDL‐related cardiovascular diseases.
Abstract While improving the thermal conductivity of composites, single‐size carbon nanotubes (CNT) often degrade their mechanical properties due to the agglomerates. To overcome this limitation, this study reported thermoplastic resin matrix composites synergistically reinforced with small, medium, and large‐size carbon nanotubes (S‐CNT, M‐CNT, and L‐CNT). Using the thermal conductivity ( λ ) and mechanical properties (flexural strength [ F ], compressive strength [ C ] and tensile strength [ T ]) as the response values, we conducted 21 sets of mixing design experiments and developed the associated quadratic term models. Further multi‐objective optimization was carried out for the above response values. Optimized multiscale CNT synergistically modified composites (S‐CNT, M‐CNT, and L‐CNT contents of 1.25, 7.02, and 2.56 wt%) exhibited a λ value of 1.168 W/mK, which was 121% higher than that of pure composite and also superior to the same content of S‐CNT‐ (1.031 W/mK), M‐CNT‐ (1.016 W/mK), and L‐CNT‐modified composites (0.983 W/mK). Additionally, the optimized composite demonstrated excellent mechanical properties ( F = 1482 MPa, C = 848 MPa, and T = 1759 MPa), which were 13%, 11%, and 13% higher than those of the pure composites, respectively, and also surpassed those of the S‐CNT‐, M‐CNT‐and L‐CNT‐modified composites. Highlights Using three different scales of carbon nanotubes modified CF/PPBESK composites. Polynomial modeling of composite's thermal conductivity and mechanical properties. Synergistic interactions between carbon nanotubes to improve the composite's thermal conductivity and mechanical properties.
Objective To isolate and identify human endothelial progenitor cell(EPC) from peripheral blood of type 2 diabetic patients and investigate the capability of differentiation and proliferation of EPC. Methods Mononuclear cells isolated from human peripheral blood of type 2 diabetic patients (diabetics without complication,n=20;diabetics with angiopathy,n=19) and control subjects (n=21) were cultured.The appearing time and the number of cell clusters and spindle-shaped cells were observed respectively.Attached spindle-shaped cells were detached and labeled with a series of antibodies against blood vessel endothelial-specific markers.Fluorescence-activated cell sorting (FACS) detection of EPC was performed on attached spindle cells after 7 days. Results The number of EPC and EPC-bearing clusters in diabetic vascular complication group were significantly fewer than those of nondiabetic control subjects and diabetics without complication (P0.01).The number of clusters were inversely correlated with HbA1c levels (R=-0.749,P0.05) and the course of diabetes(R=-0.406,P0.01). Conclusions There are endothelial progenitor cells in human peripheral blood, which can differentiate into endothelial cells.The dysfunction of EPC in diabetics is significantly correlated with the HbA1c levels and the course of diabetes.
Microgrids, as a new type of power supply network that connects distributed energy sources with power loads, can operate in both grid-connected and islanded states. It has the advantages of high reliability and flexible configuration. When the microgrid operates in islanding mode, ensuring voltage and frequency stability becomes a primary focus of research. This paper provides a brief overview of the master-slave control and peer-to-peer control strategies used in microgrids, analyzing the advantages and disadvantages of each approach. The application of droop control strategies to microgrid converters is emphasized. This research analyzes the implementation of droop control strategies in addressing microgrid frequency and power offsets. Given the advantages of the synchronized fixed-frequency droop control method, the authors provide a detailed overview of this strategy, which is based on the global satellite navigation system (GPS). On this basis, a comprehensive comparison of various synchronous frequency control methods is conducted, analyzing the advantages and disadvantages of each approach. Finally, the research findings in this area are summarized, and the future development trends of research in this field are discussed and anticipated.
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