Performance-based seismic isolation design using the theory of spatially concave friction distribution

Seismic isolation devices were designed to protect three similar building structures, containing different objects with different fragilities, in a strong earthquake region. And a performance-based assessment framework, established by the PEER, was used to identify the seismic isolation efficiency of these devices. It optimized the ratios of spring part, viscous damping part and friction part in the seismic isolation devices, aiming at different functional buildings. Results show that a spatially concave friction distribution, combined with a weak spring, not only can reduce the structural acceleration response during earthquakes, but also decrease the structural residual displacement after earthquakes. Moreover, the spatially concave friction distribution can dissipate earthquake energy, but cannot hinder the recentering of structure like that of general uniform friction distributions. Consequently, the spatially concave friction distribution can partly or fully replace the viscous dampers, which are more expensive and short-lived. The reasonable combination of different components in the seismic isolation devices can satisfy different seismic requirements, aiming at different functional buildings

Facile fabrication of multi-hydrogen bond self-assembly poly(Maac-co-maam) hydrogel modified pvdf ultrafiltration membrane to enhance anti-fouling property

In this work, a facile preparation method was proposed to reduce natural organics fouling of hydrophobic membrane via UV grafting polymerization with methacrylic acid (MAAc) and methyl acrylamide (MAAm) as hydrophilic monomers, followed by multihydrogen bond self-assembly. The resulting poly(vinylidene fluoride)-membranes were characterized with respect to monomer ratio, chemical structure and morphology, surface potential, and water contact angle, as well as water flux and organic foulants ultrafiltration property. The results indicated that the optimal membrane modified with a poly(MAAc-co-MAAm) polymer gel layer derived from a 1:1 monomer ratio exhibited superior hydrophilicity and excellent gel layer stability, even after ultrasonic treatment or soaking in acid or alkaline aqueous solution. The initial water contact angle of modified membranes was only 36.6° ± 2.9, and dropped to 0° within 13 s. Moreover, flux recovery rates (FRR) of modified membranes tested by bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA) solution, respectively, were all above 90% after one-cycle filtration (2 h), significantly higher than that of the pure membrane (70–76%). The total fouling rates (R$_{t}$) of the pure membrane for three foulants were as high as 47.8–56.2%, while the Rt values for modified membranes were less than 30.8%. Where R$_{t}$ of BSA dynamic filtration was merely 10.7%. The membrane designed through grafting a thin-layer hydrophilic hydrogel possessed a robust antifouling property and stability, which offers new insights for applications in pure water treatment or protein purificatio

Performance-based seismic isolation design using the theory of spatially concave friction distribution

Seismic isolation devices were designed to protect three similar building structures, containing different objects with different fragilities, in a strong earthquake region. And a performance-based assessment framework, established by the PEER, was used to identify the seismic isolation efficiency of these devices. It optimized the ratios of spring part, viscous damping part and friction part in the seismic isolation devices, aiming at different functional buildings. Results show that a spatially concave friction distribution, combined with a weak spring, not only can reduce the structural acceleration response during earthquakes, but also decrease the structural residual displacement after earthquakes. Moreover, the spatially concave friction distribution can dissipate earthquake energy, but cannot hinder the recentering of structure like that of general uniform friction distributions. Consequently, the spatially concave friction distribution can partly or fully replace the viscous dampers, which are more expensive and short-lived. The reasonable combination of different components in the seismic isolation devices can satisfy different seismic requirements, aiming at different functional buildings

Potential Mechanisms Responsible for the Antinephrolithic Effects of an Aqueous Extract of Fructus Aurantii

The potential effects of Fa extract on the prevention and treatment of CaOx nephrolithiasis were analyzed in an ethylene glycol- (EG-) induced CaOx crystallization model in rats and an in vitro assay. Multiple biochemical variables were measured in the urine and kidney. Kidney sections were subjected to histopathological and immunohistochemical analyses. Urolithiasis-related osteopontin (OPN) was evaluated by Western blotting. The in vitro assay revealed the significant inhibition of crystal formation (3.50±1.43) and dilution of formed crystals (12.20±3.35) in the group treated with 1 mg/mL Fa extract compared with the control group (52.30±4.71 and 53.00±4.54, resp.) (p<0.05). The in vivo experiments showed that prophylactic treatment with Fa aqueous extract significantly prevented EG-induced renal crystallization and pathological alterations compared with nephrolithic rats (p<0.05). Significantly lower levels of oxidative stress, oxalate, and OPN expression as well as increased citrate and urine output levels were observed in both the low- and high-dose prophylactic groups (p<0.05). However, in the low- and high-dose therapeutic groups, none of these indexes were significantly improved (p>0.05) except for urinary oxalate in the high-dose therapeutic groups (p<0.05). Fa extract prevented CaOx crystallization and promoted crystal dissolution in vitro. Additionally, it was efficacious in preventing the formation of CaOx nephrolithiasis in rats