Search

The rationality and reliability of the damping reduction factor are of great significance to the seismic design of building structures. However, the values of damping reduction factor predicted by the existing models have great dispersions, which are mainly related to the regression model and the considered influencing factors. Based on the linear time history analysis of a single-degree-of-freedom system under 4716 ground motions, the influence degrees of the damping ratio, the natural vibration period, the ratio between the ground predominant period and the natural vibration period, the earthquake magnitude, the rupture distance, the site type (the average shear wave velocity in the top 30 m of soil), the significant duration, and the peak ground velocity to acceleration ratio (PGV/PGA) on the damping reduction factor are evaluated by the Spearman rank correlation coefficient. After that, improved damping reduction factor models are respectively proposed for different response spectra, in which only the damping ratio and the natural vibration period are considered as variables. Through the comparison with the existing damping reduction factor models and the robustness test under different natural ground motions, the improved damping reduction factor models are proved to have a reasonable expression form and strong robustness, which can accurately predict the damping reduction factors for different response spectra.

The misuse of tetracycline (TC) will cause adverse effects on environment and has become a serious problem threatening human health. In this work, a novel bifunctional europium-based metal organic framework (1) containing characteristic metal chains was successfully synthesized via a facile one-pot hydrothermal method for the first time and used in simultaneous detection and removal of TC. Detailed characterizations including scanning electron microscope, energy dispersive X-ray spectroscope, Fourier-transform infrared, X-ray diffraction and X-ray single crystal diffraction were conducted to confirm the successful synthesis of 1. Subsequently, the prepared 1 showed significant fluorescence enhancement at 615 nm with a wide sensitive range (0.05–60 μM) and low detection limit (3 nM) for detection of TC under pH 9. The excellent adsorption behaviours (387.14 mg g−1) of 1 toward TC were demonstrated by kinetic and equilibrium experiments. Possible mechanisms of recognition and adsorption including host-guest capability of Eu nodes, hydrogen bonding, π-π interactions and electrostatic attraction were further explored. In addition, the practical feasibilities of 1 for TC sensing were further investigated in real samples with satisfactory recoveries (94.89 %−112.86 %, RSD ≤ 6.03 %). This work provides a facile strategy for design of MOF-based bifunctional turn-on fluorescence sensor for efficient TC monitoring.

It is assumed that acute myocardial infarction affects renal function. To study the mechanism, we used mice following permanent ligation of their left coronary artery that results in extensive myocardial infarction. Soon after ligation, there was a marked rise in circulating pro-inflammatory cytokines and malondialdehyde (thiobarbituric acid-positive evidence of lipid peroxidation). Renal function had significantly declined by the third day in association with mild fibrosis, and swelling of glomeruli and tubules. There was a significant increase in the expression of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), interelukin-1β, vascular cell adhesion molecule-1, and thiobarbituric acid-reactive substances in the kidney. Renal function showed some recovery by Day 21; however, there was progressive fibrosis of the kidneys. LOX-1 knockout mice had significantly diminished increases in systemic and renal pro-inflammatory cytokines, malondialdehyde, structural alterations, and decline in renal function than the wild-type mice following ligation of the left coronary artery. Cardiac function and survival rates were also significantly better in the LOX-1 knockout mice than in the wild-type mice. Hence, severe myocardial ischemia results in renal dysfunction and histological abnormalities suggestive of acute renal injury. Thus, LOX-1 is a key modulator among multiple mechanisms underlying renal dysfunction following extensive myocardial infarction.

Statins, inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, have been shown to induce both angiogenic and angiostatic responses. We attempted to resolve this controversy by studying the effects of two different statins, rosuvastatin and simvastatin, in two different assay systems. In the matrigel angiogenesis assay, both statins enhanced tube formation by human umbilical vein endothelial cells (HUVECs, p

Vascular Ca2+ channels play an important role in the pathogenesis of hypertension, but little is known about their role in atherosclerosis. We studied the expression and function of CaV1.2 in aorta from LDLR -/- mice fed normal or high cholesterol (HC) diet for 26 weeks. HC diet markedly increased serum triglyceride, total cholesterol and phopholipid levels and generated atherosclerotic plaques, but had no significant effect on blood pressure. Immunohistochemistry (Figure) and Western blot analysis (inset) revealed that aortic CaV1.2 expression was significantly upregulated in mice fed HC diet compared to normal (N) diet. The majority of the CaV1.2 expression was in vascular smooth muscle cells (VSMCs), rather than atherosclerotic plaques. Despite overexpression of CaV1.2 subunits, aortic rings from the HC mice had a diminished constrictor response to CaV1.2 channel activator FPL64176, perhaps a result of reduced expression of the contractile protein α-actin. Inclusion of 1 mg/kg/d rosuvastatin or amlodipine in the HC diet ameliorated all observed changes. These data suggest that during atherosclerosis: (1) VSMCs develop a phenotype switch involving upregulation of CaV1.2 subunits but downregulation of contractile protein α-actin, and therefore reduced contractility; (2) CaV1.2 channels may be involved in atherosclerosis.View Large Image | View Hi-Res Image | Download PowerPoint Slide