127 research outputs found
Is the red dragon green? An examination of the antecedents and consequences of environmental proactivity in China
China is the worldās second largest economy and the largest emitter of carbon dioxide, yet we know little about environmental proactivity in the most populated country in the world. We address this gap through a survey of 161 Chinese companies with two respondents per firm (N = 322) where we seek to identify the antecedents and consequences of environmental proactivity. We identify two categorizations of environmental proactivity: Environmental operational improvements and environmental reporting. We find that ecological motivations and regulatory stakeholder pressure are positively related to both types of environmental proactivity, and external stakeholder pressure is negatively related to environmental reporting. Furthermore, we find that (1) if a firm is environmentally proactive (as it relates to either measure) and they are ecologically motivated, there is a positive and significant cost advantage, and (2) if a firm makes use of environmental operational improvement and they are competitively motivated, there is a positive and significant reputation advantage. Implications for researchers, managers, and policy-makers in China are discussed
Aortic valve tear with severe aortic regurgitation following blunt chest trauma
An aortic valve tear associated with aortic regurgitation following blunt chest trauma is seldom seen. In this case, a 55-year-old man sustained a non-penetrating chest injury caused by a sudden fall from 10 meters. This led to a sizable tear in the left coronary cusp associated with severe aortic insufficiency. The case was treated successfully by surgical replacement of the aortic valve with a mechanical prosthesis
Protective effect of glucosamine cyclohexyl ester on osteoarthritis in rat via targeting expressions of matrix metalloproteinase and tissue inhibitor of metalloproteinases-1
Purpose: To investigate the therapeutic effect of glucosamine cyclohexyl ester on osteoarthritis (OA) in a rat model.Methods: Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot assays were used to analyze the effect of glucosamine cyclohexyl ester on changes in mRNA and protein expressions of matrix metalloproteinase and tissue inhibitor of metalloproteinases-1 in isolated rat chondrocytes, and in a rat model of OA. The rat model of OA was prepared by injecting monoiodoacetate to Sprague-Dawley rats via intra-articular route.Results: Treatment of the chondrocytes with glucosamine cyclohexyl ester for 48 h prevented interleukin-1 Ī² (IL-1Ī²)-mediated increases in mRNA and proteinĀ expressions in matrix metalloproteinases-1, -3 and -13, and also blocked IL-1Ī²-induced decreases in mRNA and protein expressions of tissue inhibitor of metalloproteinase-1. Glucosamine cyclohexyl ester treatment also blocked the onset of morphological changes such as irregular surface, adhesion of tissues andpresence of osteophytes in the femoral condyle surface of the OA rats. Mankin score for control, OA and glucosamine cyclohexyl ester treatment groups were 0.98 Ā± 0.15, 8.35 Ā± 0.88 and 2.39 Ā± 0. 67 (p = 0.002), respectively. Treatment of OA rats with glucosamine cyclohexyl ester also inhibited increases in the activities of matrix metalloproteinases-1, -3 and -13, and decreases of tissue inhibitor of metalloproteinase-1 mRNA and protein expressions. Treatment of chondrocytes and OA rats with IL-1Ī² caused no significant changes in the levels of H3K27 and H4K8.Conclusion: These results show that glucosamine cyclohexyl ester prevents OA by targeting the expressions of matrix metalloproteinases-1, -3 and -13 and tissue inhibitor of metalloproteinases-1.Keywords: Metalloproteinases, Interleukin, Mankin score, Osteoarthritis, Cartilag
Multi-damage detection in composite structure
In this paper a pre-stack reverse-time migration concept of signal processing techniques is developed and adapted to guided-wave propagation in composite structure for multi-damage imaging by experimental studies. An anisotropic laminated composite plate with a surface-mounted linear piezoelectric ceramic (PZT) disk array is studied as an example. At first, Mindlin Plate Theory is used to model Lamb waves propagating in laminates. The group velocities of flexural waves are also derived from dispersion relations and validated by experiments. Then reconstruct the response wave fields with reflected data collected by the linear PZT array. Reverse-time migration technique is then performed to back-propagate the reflected energy to the damages using a two-dimensional explicit finite difference algorithm and damages are imaged. Stacking these images together gets the final image of multiple damages. The results show that the pre-stack migration method is hopeful for damage detection in composite structures
Regulation of welding residual stress in laser-welded AISI 304 steel-niobium joints using a Cu interlayer
Residual stress and deformation in a welded joint will significantly reduce its service life, and thus the analysis and regulation of residual stresses are very important. In this paper, a SYSWELD software was used to numerically simulate the temperature field, residual stress field, and the welding deformation during welding with and without a Cu interlayer. Thermocouples were used to measure the thermal cycle curves, and X-ray diffraction (XRD) was used to measure the residual stresses of the joints. The results show that the addition of a Cu interlayer does not significantly change the temperature field, and that the high temperature region on the niobium side is wider. In addition, the peak temperature in the centre of the welds and the temperature gradient perpendicular to the weld are greatly reduced by a Cu interlayer. Furthermore, a Cu interlayer contributes to a certain increase in both transverse and longitudinal residual stresses. Because the weld involves three different materials, steel, niobium, and Cu, the residual stresses in the welds are more complex. The simulation of the welding deformation shows that the transverse shrinkage in the thickness direction can be homogenized by the Cu interlayer, which leads to a significant reduction in deformation.acceptedVersio
Thoracoscopic Left Atrial Appendage Excision Plus Ablation for Atrial Fibrillation to Prevent Stroke
Atrial fibrillation (AF) patients with a previous stroke are often at a high risk of recurrent stroke and bleeding. Anticoagulation therapy in such patients is a challenging dilemma. Thoracoscopic left atrial appendage excision (LAAE) plus AF ablation is an interventional approach offered to some AF patients. We hypothesized that this approach may be suitable as a secondary stroke prevention strategy for these high-risk patients. Between January 2013 and December 2016, a total of 44 patients (26 male; mean age 65.0 Ā± 9.1 years) with nonvalvular AF and a previous stroke or systemic thromboembolic event were enrolled. The patients underwent thoracoscopic LAAE plus AF ablation by experienced operators and were followed up for 2 years (at 1, 3, 6, 9, and 12 months postoperatively and every 6 months thereafter). Thromboembolic and major bleeding events were recorded. Cerebral computed tomography or magnetic resonance imaging and 7-day Holter monitoring were performed annually. Mean CHA2DS2-VASc and HAS-BLED scores were 4.2 Ā± 1.2 and 3.3 Ā± 0.7, respectively. All patients discontinued oral anticoagulation therapy after the surgical intervention. One patient suffered a periprocedural transient ischemic attack, and another was diagnosed with a new ischemic stroke at 491 days after surgery. The annual rate of total thromboembolism was 2.05%. No deaths or major bleeding events were observed postoperatively. The rate of successful AF ablation with no AF recurrence was 76.3%. Transthoracoscopic LAAE plus AF ablation may be a promising approach for this high-risk population. Thromboembolism event in this secondary prevention cohort was low, even without oral anticoagulation treatment
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