Professor T. T. Soong is one of the early pioneers in fi eld of earthquake response control of structures. A new type of smart damper, which is based on an Energy Dissipating Restraint (EDR), is presented in this paper. The EDR by Nims and Kelly, which has a triangle hysteretic loop, behaves like an active variable stiffness system (AVS) and possesses the basic characteristics of a linear viscous damper but has diffi culty in capturing the output and large stroke simultaneously needed for practical applicataions in engineering structures. In order to overcome this limitation, the friction surface in the original Sumitomo EDR is divided into two parts with low and high friction coeffi cients in this paper. The results of fi nite element analysis studies show that the new type of smart friction damper enables large friction force in proportion to relative displacement between two ends of the damper and has a large allowable displacement to fi t the demands of engineering applications. However, unlike the EDR by Nims and Kelly, this type of friction variable damper cannot self re-center. However, the lateral stiffness can be used to restore the structure. The nonlinear time history analysis of earthquake response for a structure equipped with the proposed friction variable dampers was carried out using the IDARC computer program. The results indicate that the proposed damper can successfully reduce the earthquake response of a structure.

A passive tuned mass damper (TMD) fabricated using the Reid damping, referred to as the Reid-TMD, is proposed. First, the characteristics of the Reid damping model are introduced, followed by the presentation of a passive variable friction damper to achieve this model. Next, the steady-state response of single-degree-of-freedom structures with the Reid-TMD under a harmonic load is solved by the harmonic balance method (HBM), together with an error analysis of the results. Subsequently, the optimization and control effect of the Reid-TMD damping system are analyzed and compared with the traditional viscous damping TMD. The results show that under the action of a harmonic load or seismic load, the vibration suppression effect of the Reid-TMD with the same mass ratio is essentially equivalent to the traditional viscous damping TMD. In addition, the damping control effect increases with the increase in mass ratio. When the mass ratio is less than 0.05, the energy dissipation coefficient is less than 0.5 and the frequency ratio is less than 0.95. For parameters within this range, the steady-state response of the seismic reduction structure with the Reid-TMD is solved by the HBM. If the parameters of the Reid-TMD are outside this range, the error of the HBM becomes large, and recourse should be changed to general numerical methods. The optimum parameters of the Reid-TMD are determined through an optimization analysis for the mass ratio in the range of 0.005–0.1. While using the Reid-TMD for the vibration absorption design, the optimum parameters can be acquired directly by using the established tables. Because the passive variable friction damper has good durability and economy, the application of the Reid-TMD is beneficial to shock absorption technology.

Under harmonic load and random stationary white noise load, the existing fitting formulas are not suitable for calculating the optimal parameters of large mass ratio tuned mass dampers (TMDs). For this reason, the optimal parameters of large mass ratio TMDs are determined by numerical optimisation methods, and a revised fitting formula is proposed herein based on a curve fitting technique. Finally, the dynamic time history analysis method is used to study the control effect of large mass ratio TMDs. The results show that when the mass ratio is large, the error between the existing fitting formula and the actual optimal value is quite large, and the revised fitting formula is applicable to the parameter design of the traditional small mass ratio and large mass ratio (≤1) TMDs. When the ratio of local base soil predominant frequency to structure vibration frequency is greater than 4, the optimal parameters of a TMD under white noise excitation can be calculated according to the revised fitting formula, and the remaining conditions should be determined by numerical optimisation. In addition, a large mass ratio TMD reduces the dynamic response of the main structure effectively compared with a small mass ratio TMD and reduces the relative displacement between the TMD and main structure.

Context Pterostilbene (PTE), a common polyphenol compound, exerts an anti-inflammatory effect in many diseases, including acute lung injury (ALI). Objective This study explores the potential mechanism of PTE pre-treatment against lipopolysaccharide (LPS)-induced ALI. Materials and methods Sixty Sprague-Dawley rats were divided into control, ALI, 10 mg/kg PTE + LPS, 20 mg/kg PTE + LPS, and 40 mg/kg PTE + LPS groups. At 24 h before LPS instillation, PTE was administered orally. At 2 h before LPS instillation, PTE was again administered orally. After 24 h of LPS treatment, the rats were euthanized. The levels of inflammatory cells and inflammatory factors in the bronchoalveolar lavage fluid (BALF), the expression of nuclear receptor subfamily 4 group A member 1 (NR4A1), and the nuclear factor (NF)-κB pathway-related protein levels were detected. NR4A1 agonist was used to further investigate the mechanism of PTE pre-treatment. Results After PTE pre-treatment, the LPS induced inflammation was controlled and the survival rate was increased to 100% from 70% after LPS treatment 24 h. For lung injury score, it decreased to 1.5 from 3.5 after treating 40 mg/kg PTE. Compared with the control group, the expression of NR4A1 in the ALI group was decreased by 20–40%. However, the 40 mg/kg PTE pre-treatment increased the NR4A1 expression by 20–40% in the lung tissue. The results obtained with pre-treatment NR4A1 agonist were similar to those obtained by pre-treatment 40 mg/kg PTE. Conclusions PTE pre-treatment might represent an appropriate therapeutic target and strategy for preventing ALI induced by LPS.

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