Finite element thermo-mechanical analysis of concrete box-girders

A full-scale 3D thermo-mechanical Finite Element (FE) model was conducted in this research to investigate the effect of open-field thermal loads on the structural response of box-girder bridges. A box-girder bridge with a span of 50 m was analyzed for temperature, radiation and displacement fields using COMSOL Multiphysics. To verify the FE model, a full-scale experimental box-girder segment was constructed and instrumented with temperature, radiation and other sensors. From the experimental records, three days with extreme temperature and radiation measurements were selected. The stresses and displacements are discussed at specific points along the 24 h of the selected days and at specific times along critical sections. The FE analysis showed that the vertical and lateral stress distributions exhibited approximately similar behaviors to their corresponding temperature distributions with minor differences but with reversed sign. The results also showed that the maximum stress was compressive, which was −3.35 MPa in summer −3.83 MPa in winter. On the other hand, the maximum vertical and lateral displacements were 12.5 and 1.2 mm, respectively in summer and 2.7 and 1.9 mm in winter

Concentrated Fish Oil (Lovaza®) Extends Lifespan and Attenuates Kidney Disease in Lupus-Prone Short-Lived (Nzbxnzw)F1 Mice

A growing number of reports indicate that anti-inflammatory actions of fish oil (FO) are beneficial against systemic lupus erythematosus (SLE). However, the majority of pre-clinical studies were performed using 5-20% FO, which is higher than the clinically relevant dose for lupus patients. The present study was performed in order to determine the effective low dose of FDA-approved concentrated FO (Lovaza®) compared to the commonly used FO-18/12 (18-Eicosapentaenoic acid [EPA]/12-Docosahexaenoic acid [DHA]). We examined the dose-dependent response of Lovaza® (1% and 4%) on an SLE mouse strain (NZBxNZW)F1 and compared the same with 1% and 4% placebo, as well as 4% FO-18/12, maintaining standard chow as the control. Results show for the first time that 1% Lovaza® extends maximal lifespan (517 d) and 4% Lovaza® significantly extends both the median (502 d) and maximal (600 d) life span of (NZBxNZW)F1 mice. In contrast, FO-18/12 extends only median lifespan (410 d) compared to standard chow diet (301 d). Additionally, 4% Lovaza® significantly decreased anti-dsDNA antibodies, reduced glomerulonephritis and attenuated lipopolysaccharide-induced pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) in splenocytes compared to placebo. 4% Lovaza® was also shown to reduce the expression of inflammatory cytokines, including IL-1β, IL-6 and TNF-α, while increasing renal anti-oxidant enzymes in comparison to placebo. Notably, NFκB activation and p65 nuclear translocation were lowered by 4% Lovaza® compared to placebo. These data indicate that 1% Lovaza® is beneficial, but 4% Lovaza® is more effective in suppressing glomerulonephritis and extending life span of SLE-prone short-lived mice, possibly via reducing inflammation signaling and modulating oxidative stress

The protective effects of L-carnitine and vitamin E in rat lenses in irradiation-induced oxidative injury

Objectives. The aim of this study was to evaluate the antioxidant role of L-carnitine (LC) and vitamin E against radiation-induced cataracts in rat lenses after total cranial irradiation with a single 5 Gray (Gy) dose of gamma irradiation. Material and Methods. Thirty two Sprague-Dawley rats were used for the experiment. The control group did not receive LC and vitamin E or irradiation but received both 0.1 ml physiological saline intraperitoneally and sham irradiation. The irradiation (IR) group received 5 Gy gamma irradiation to the total cranium as a single dose plus 0.1 ml physiological saline intraperitoneally. The IR plus vitamin E group received irradiation to total cranium plus 10 mg/kg/day vitamin E intraperitoneally. The IR plus LC group received irradiation to total cranium plus 100 mg/kg/day LC intraperitoneally. Biochemical parameters measured in murine lenses were carried out using spectrophotometric techniques. Results. Total superoxide scavenger activity (TSSA), non-enzymatic superoxide scavenger activity (NSSA), glutathione-S- transferase (GST) and glutathione reductase (GRD) activities, significantly increased in the control, IR plus vitamin E and LC plus IR groups when compared with the IR only group. Lens TSSA and NSSA activities in the control group were significantly increased compared to that of the IR only group, but decreased compared to those of the IR plus vitamin E and IR plus LC groups. Lens xanthine oxidase (XO) activity in the IR group significantly increased compared to those of other groups. Conclusions. Results show that LC and vitamin E prevented oxidative stress by scavenging free radicals generated by ionizing radiation in rat lenses (Adv Clin Exp Med 2011, 20, 1, 15-21). © Copyright by Wroclaw Medical University

Endurance training attenuates the oxidative stress due to acute exhaustive exercise in rat liver

The aim of this study was to investigate whether an 8-week treadmill training attenuates exerciseinduced oxidative stress in rat liver. Male rats were divided into untrained and trained groups. Endurance training consisted of treadmill running at a speed of 2.1 km/h, 1.5 h/day, 5 days a week for 8 weeks. To see the effects of endurance training on acute exhaustive exercise induced oxidative stress, untrained and trained rats were further devided into two groups: animals killed at rest and those killed after acute exhaustive exercise, in which the rats run at 2.1 km/h (10% uphill) until exhaustion. Acute exhaustive exercise increased malondialdehyde level in untrained but not in trained rats. It decreased the activity of glutathione peroxidase and total (enzymatic plus non-enzymatic) superoxide scavenger activity in untrained rats and catalase activity in trained rats. However, it did not affect glutathione S-transferase, glutathione reductase, superoxide dismutase and non-enzymatic superoxide radical scavenger activities in both trained and untrained rats. On the other hand, endurance training decreased glutathione peroxidase and glutathione S-transferase activities. The results suggested that endurance training attenuated exercise-induced oxidative stress in liver, probably by preventing the decreases in glutathione peroxidase and total superoxide scavenger activities during exercise. © 2008 Akadémiai Kiadó