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Negative stiffness mechanism has been found able to improve damping performance of dampers on a stay cable which otherwise is limited by the damper installation distance from a cable end. This study provides a practical negative stiffness device (NSD) with adjustable negative stiffness and experiments are performed to validate the negative stiffness effect. The NSD is then combined with a viscoelastic damper in parallel or series for cable damping improvement. Explicit design formulas are derived for optimal design with a target enhancement effect in damping considering the damper described respectively using the Kelvin model and the linear hysteretic damping model. The formulas are verified by analytical and numerical solutions. Parametric analyses show damping enhancement effects of the NSD and it is found more efficient when combined with a damper in series because both deformation amplitudes of the damper and the NSD are further increased in this configuration. Subsequently, case studies are carried out based on two cables of the Sutong Bridge respectively with a shear-type viscous damper and a high damping rubber damper. The results show that the designed NSD can fulfill practical requirements. Particularly, a 100% increase in damping can be achieved by the presented NSD when combined with the damper installed on a cable of 546.9 m long. [Display omitted] • Practical NSDs are presented and experimentally tested for cable damping improvement. • Damping effects of a cable with the NSD and dampers in parallel and series are investigated. • The NSD is shown to be more efficient when placed with the dampers in series configuration. • Achieved negative stiffness is found sufficient for stay cables even longer than 500 m. [ABSTRACT FROM AUTHOR]

This paper presents a full-scale experimental study on dynamics of hybrid cable networks composed of three real cables, a rigid cross-tie and three viscous-shear dampers. For comparison, an improved numerical model of cable networks considering cross-ties, dampers, and cross-tie pretension is also provided. The measured frequencies and mode shapes of the cable networks with different configurations and cross-tie locations are found in good agreement with corresponding theoretical predictions. The characteristics of damping variation with respect to cross-tie location and the layout observed from the experiments are generally consistent with the theoretical analysis, although there is a discrepancy between identified and computed values of damping. The experiments show that the cross-tie when located close to the dampers can lead to a reduction in modal damping of low-frequency modes. The dampers in the cable networks provide relatively large damping to global modes and modes dominated by vibrations of cable segments to which the damper is connected. Furthermore, when the cross-tie is installed far away from the external dampers, the cross-tie extended to the ground can effectively improve the system modal damping, as the length of the cable is reduced equivalently and the relative distance of the damper away from the closest anchor as compared to the cable length is increased. [ABSTRACT FROM AUTHOR]

Antibiotics resistance of H. pylori has been increasing constantly accompanied with decreasing clearance rate clinically, which is demonstrated to be closely related to biofilms with higher resistance than planktonic bacteria for the dense extracellular polymeric substances. Rhamnolipid (RHL) is proved to not only damage the structure of biofilm, but also potentially inhibit bacterial adhesion. To investigate if RHL could promote eradicating rate of the conventional triple therapy to H. pylori biofilm and hence attenuate the resistance and relapse of H. pylori , first-line antibiotics clarithromycin (CLR), amoxicillin (AMX) or/and proton pump inhibitor (PPI) involved single, dual or triple therapies were compared with RHL-containing drug combinations on eradicating H. pylori biofilm. The residual biofilm biomass, the survival of bacteria inside the remaining biofilm and the planktonic bacteria dispersed from the biofilm after treatment were tested. Combination with RHL significantly improved the ability of antibiotics to eradicate H. pylori biofilm, especially RHL combined with AMX and PPI could eradicate more than 95% of biofilm showing much more effective ability than the conventional triple therapy CLR + AMX + PPI. Additionally, the combination of RHL and antibiotics could effectively inhibit the biofilm formation at lower concentration. Thus, RHL might be used as a potential antibiotic adjuvant on anti- H. pylori therapy to enhance eradicating ability of antibiotics to biofilms. • RHL enhances the effect of antibiotics on eradicating H. pylori biofilms and inhibiting biofilm formation. • RHL effectively decreases the survival rate of H. pylori dispersed from the biofilms. • RHL can be developed as an antibiotic adjuvant for anti- H. pylori therapy. [ABSTRACT FROM AUTHOR]