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A tuned viscous mass damper (TVMD) is a novel type of vibration absorber which exhibits outstanding vibration control performance. In this study, an experiment was conducted to investigate the robustness of a TVMD for the vibration control of a typical single degree of freedom (SDOF) structural system. To that end, a new eddy-current TVMD (EC-TVMD) was developed as a representative TVMD device. The TVMD-controlled SDOF system was investigated using a series of shaking table tests. The influence of variations in stiffness of the primary structure and TVMD damping (including damping amplitude and damping nonlinearity) was assessed. The variation in TVMD damping exerted a smaller influence on control performance than the variation in primary structure stiffness. The robustness of TVMD control was enhanced by increasing the inertance-to-mass ratio. Parametric analyses using a numerical model further confirmed the experimental observations, and indicated that a TVMD exhibits improved robustness compared with a conventional tuned mass damper (TMD) which is sensitive to the detuning effect. The vibration control mechanism and robustness characteristics of the TVMD were further revealed by a Kelvin-Voigt model. Finally, the influence of damping nonlinearity was verified by the nonlinear time history analysis of a finite element model of the test structure. The results indicate that damping nonlinearity has limited influence on the control of a TVMD with nonlinear damping as long as this TVMD has the same peak displacement amplification ratio as the optimal linear design.

Multi-person pose tracking task aims to estimate and track person keypoints in videos. Most of the previous methods follow the general track-by-detection strategy that ignores the consistent pose information during the whole framework. Thus, they often suffer from missing detections or inaccurate human association in challenging scenes with motion blur or person occlusion. To handle those problems, we propose a pose-guided tracking-by-detection framework that fuses pose information into both video human detection and human association procedures. In the video human detection stage, we adopt the pose-guided person location prediction exploiting the temporal information to make up missing detections. Technically, pose heatmaps are utilized to cope with the person-specific intra-class distractors. Furthermore, in the human association stage, we propose an appearance discriminative model based on the hierarchical pose-guided graph convolutional networks (PoseGCN). The PoseGCN-based model exploits human structural relations to boost person representation. Extensive experiments show the superiority of our method on the challenging pose tracking benchmark. Our proposed method ranks first on the PoseTrack leaderboard. 1 1 http://posetrack.net/leaderboard.php till the submission date (22-Aug-2019) of this paper. Our code has been publicly available at https://github.com/human-centric982/PGPT .

Exposed chronic wounds are usually covered by hypoxic tissues accompanied with necrosis, persistent inflammation and anaerobic infections. Since atmospheric oxygen air can only penetrate about 0.3 mm tissues, meanwhile oxygen from the circulation is difficult to reach chronic wounds through the destroyed blood vessels, a solution to deliver oxygen locally and permeably is urgently needed. Herein we report a technique to reform traditional gel-based wound dressings by adding lyophilized oxygen encapsulated nanoparticles, which can deliver dissolved oxygen locally into wound surface. This delivery technique can potentially evaluate the therapeutic effects on hypoxic epithelial, endothelial and fibroblasts in vitro. Further experiments confirm the effects on both open wounds bearing and flap transplanted diabetic mice models. Considering its biocompatibility, effectiveness and practicality, we believe our hydrogel has significant transformation value to care and accelerate the healing of various clinical wounds, especially chronic wound.

Hypoxia-based agents (HBAs), such as anaerobic bacteria and bioreductive prodrugs, require both a permeable and hypoxic intratumoural environment to be fully effective. To solve this problem, herein, we report that perfluorocarbon nanoparticles (PNPs) can be used to create a long-lasting, penetrable and hypoxic tumour microenvironment for ensuring both the delivery and activation of subsequently administered HBAs. In addition to the increased permeability and enhanced hypoxia caused by the PNPs, the PNPs can be retained to further achieve the long-term inhibition of intratumoural O2 reperfusion while enhancing HBA accumulation for over 24 h. Therefore, perfluorocarbon materials may have great potential for reigniting clinical research on hypoxia-based drugs., Hypoxia-based agents need permeable and hypoxic intratumour environment to be effective. Here, the authors show that perfluorocarbon nanoparticles promote increased permeability and sustained hypoxia to improve accumulation of hypoxia-based agents, and inhibit intratumour oxygen reperfusion.

Recently, deep learning methods have proved exceptional performance in video action recognition. However, it remains a challenging problem to extract discriminative features from videos effectively. Most existing methods mainly focus on spatial-temporal information separately. In this paper, we propose a novel Stacked Diverse Attention Network (SDAN). It uses a Multi-dimensional Attention Module to emphasize informative maps along the channel and spatial-temporal dimension. Besides, a Supervised Attention Module is designed to generate a weighted feature map in a class-supervised way. Compared with previous methods, the proposed method has the following advantages: (1) The Multi-dimensional Attention Module can exploit effective combinations and correlation of attention mechanisms along different dimensions. (2) The Supervised Attention Module improves the network capability supervised directly by action labels which reveal the class-related object and limb information. Extensive experimental evaluation demonstrates the effectiveness of the proposed approach and establishes significant results on Kinetics400, UCF101 and HMDB51 Datasets. Codes are available on https://github.com/jeff62802217/SDAN-Pytorch.

The porous organic polymers have been considered as effective materials for gas storage and adsorption. Herein, we synthesized highly crystalline nitrogen-rich covalent triazine frameworks (CTFs) by polycondensation for preparing the novel hyper-cross-linked conjugated polymers (HCCPs) with tunable specific surface area and pore volume through coupling Friedel-Crafts reaction, in which 1,4-Bis(chloromethyl)benzene and 4,4-Bis(chloromethyl)biphenyl as the expansion molecules were pillared between the layers of CTF-HUST. This technology not only increased the specific surface area and total pore volume of CTF-HUST by 2.56 and 4.68 times, but also greatly enhanced the utilization of adsorption sites of CTF-HUST. The HCCP2-1.25 exhibited the highest surface area (1349.29 m2g-1) among these HCCPs and demonstrated excellent adsorption performance for ethyl acetate (1605.14 mg/g), ethanol (1371.49 mg/g), 1,2-Dichloroethane (1971.68 mg/g), benzene (1151.77 mg/g) and toluene (1024.28 mg/g) due to the multiple C-H…O, C-H…Cl, O-H…N and C-H…π interactions between volatile organic compounds (VOCs) and HCCPs framework. Moreover, CO2 and H2 storage capacities of the HCCP2-1.25 were 8.02 wt % and 1.54 wt %, 1.66 and 1.67 times higher than CTF-HUST, respectively. This study developed a simple and effective molecular expansion strategy to synthesize a series of novel high-surface-area porous polymers for potential applications in the environmental field.

This paper presents the experimental and simulation study of circular steel arches attached on the steel columns through the rigid connection, which are loaded to failure under static load. Local buckling of the top flange at the mid-span arch or the bottom flange at end of the arch occurs under the ultimate load. The deformation shape is approximately antisymmetrical with a 0.2 rise-to-span ratio and is symmetrical with a 0.1 rise-to-span ratio. A simplified model is proposed as an arch with elastic horizontal and rotational end restraints. The corresponding stiffness is determined as equivalent horizontal and rotational stiffness at each arch end under the ultimate load. Then a large amount of parameter analysis is conducted to investigate the influence of the elastic supported stiffness, load type, rise-to-span ratio, and slenderness on the ultimate resistance. The finding is that the reduction of the ultimate resistance for the arch with the horizontal and rotational elastic end restraints is maximal under the uniform full-span vertical load, minimal under the concentrated load. Finally, a design method of the steel arch with elastic horizontal and rotational end restraints is proposed taking both ultimate resistance and maximum horizontal displacement of the supports into account for engineering reference.

The low oxygen concentration limits the therapeutic efficacy of photodynamic therapy in treating cancer cells in hypoxia, since the cytotoxic 1O2 can't be effectively generated in this condition. To overcome this, we load photosensitizer into perfluorocarbon nanodroplet, which has a high oxygen capacity to enrich O2 for photodynamic consumption. Under the well-controlled hypoxic condition, we test its efficacy both in vitro and in vivo. This method can be successfully used for destroying cancer cells in hypoxic condition.

Adhesions between homologous cancer cells play an important role in promoting tumor progression and designing tumor-targeting methods. Known as 'homologous adhesions' of cancerous cells, these are usually more specific than adhesions to normal cells and heterogenic cells, and they have been widely discovered both in vivo and in vitro. The aberrant expression of cell adhesion-related molecules (CARMs) on each species of cancer cells is mainly responsible for inducing more specific homologous adhesions. Based on the improvement of biomimetic technologies, such adhesion has been investigated and applied deeply in drug delivery systems recently. Areas covered: This review focuses on the discovery, mechanism and application of homologous adhesion and aims to assist researchers with a clear understanding for more effective development. The advantages and challenges of recent research progress and therapeutic applications are also described and discussed. Expert commentary: Homologous adhesion shows promise in providing new strategies for targeted drug delivery and tailored cancer treatments. However, the 'homing' property of certain cancer cell types remains unclear and needs to be further defined.

Objectives Aberrant transforming growth factor β (TGFβ) activation is detrimental to both nucleus pulposus (NP) cells and cartilage endplates (CEPs), which can lead to intervertebral disc degeneration (IDD). Ligustrazine (LIG) reduces the expression of inflammatory factors and TGFβ1 in hypertrophic CEP to prevent IDD. In this study, we investigate the effects of LIG on NP cells and the TGFβ signaling. Design LIG was injected to the lumbar spinal instability (LSI) mouse model. The effect of LIG was evaluated by intervertebral disc (IVD) score in the LSI mouse model. The expression of activated TGFβ was examined using immunostaining with pSmad2/3 antibody. The upright posture (UP) rat model was also treated and evaluated in the same manner to assess the effect of LIG. In ex vivo study, IVDs from four-week old mice were isolated and treated with 10−5, 10−6, and 10−7 M of LIG. We used western blot to detect activated TGFβ expression. TGFβ-treated human nucleus pulposus cells (HNPCs) were cotreated with optimized dose of LIG in vitro. Immunofluorescence staining was performed to determine pSmad2/3, connective tissue growth factor (CCN2), and aggrecan (ACAN) expression levels. Results IVD score and the percentage of pSmad2/3+ NP cells were low in LIG-treated LSI mice in comparison with LSI mice, but close to the levels in the Sham group. Similarly, LIG reduced the overexpression of TGFβ1 in NP cells. The inhibitory effect of LIG was dose dependent. A dose of 10−5 M LIG not only strongly attenuated Smad2/3 phosphorylation in TGFβ-treated IVD ex vivo but also suppressed pSmad2/3, CCN2, and ACAN expression in TGFβ-treated NP cells in vitro. Conclusions LIG prevents IDD via suppression of TGFβ overactivation in NP cells.

In this paper, we review theoretical and experimental research progress on timing properties of superconducting nanowire single-photon detectors, including six possible mechanisms that induce timing jitter and experiments towards ultra-low timing jitter.