Simplified Analytical Model for Predicting Neutral Cross-Section Position of Lenticular Deployable Composite Boom in Tensile Deformation.

Foldable and deployable flexible composite thin-walled structures have the characteristics of light weight, excellent mechanical properties and large deformation ability, which means they have good application prospects in the aerospace field. In this paper, a simplified theoretical model for predicting the position of the neutral section of a lenticular deployable composite boom (DCB) in tensile deformation is proposed. The three-dimensional lenticular DCB is simplified as a two-dimensional spring system and a rigid rod, distributed in parallel along the length direction. The position of the neutral cross-section can be determined by solving the balance equations and geometric relations. In order to verify the validity of the theoretical model, a finite element model of the tensile deformation of a lenticular DCB was established. The theoretical prediction results were compared with the finite element calculation results, and the two results were in good agreement.

LY294002 blocks the effect of dexamethasone in reducing urine protein in rats by inhibiting PI3K/Akt signaling pathway / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the involvement of PI3K/Akt signaling pathway in the changes of urine protein in adriamycin-induced nephropathic rats treated with dexamethasone and LY294002 (a PI3K inhibitor).</p><p><b>METHODS</b>SD rats were randomized into normal control group, ariamycin-induced nephropathy group (ADR group), ariamycin+dexamethasone group (DEX group), and ADR+DEX+LY294002 group (LY294002 group). On days 7, 14 and 28 after the treatments, 24-h urine was collected from the rats to analyze the total urine proteins. The renal tissues were obtained on day 28 to examine the expressions of p-AKT, AKT and Bad proteins in the cortical tissues using Western blotting; the expression of Bad mRNA in the cortical tissues was measured by QPCR.</p><p><b>RESULTS</b>Urine protein increased progressively in ADR group accompanied by significantly reduced p-AKT/AKT ratio and increased Bad mRNA expression in comparison with those in the normal control group (P<0.05). Urine protein was obviously reduced in DEX group with comparable p-AKT/AKT ratio and Bad mRNA expression level with those in the control group (P>0.05). Urine protein showed no significant reduction in LY294002 group, but the p-AKT/AKT ratio was significantly reduced and Bad mRNA expression was increased compared with those in DEX group (P<0.05).</p><p><b>CONCLUSION</b>Dexamethasone increases the expression of Bad mRNA and reduces urine protein in adriamycin-induced nephropathic rats by activating PI3K/Akt signaling pathway. LY294002 can inhibit PI3K/Akt signaling pathway to block the effect of dexamethasone, suggesting that PI3K/Akt signaling pathway is one of the signaling pathways that mediate the effect of dexamethasone on proteinuria.</p>