In the past, adaptive tuned vibration absorbers (ATVAs) based on magnetorheological elastomers (MREs) have mainly been developed in a shear working mode. The enhancing effect of MREs in squeeze mode has already been investigated, but ATVAs in squeeze mode have rarely been studied. This paper reports the development of a compact squeeze MRE absorber and its subsequent performance in various magnetic fields characterized under various frequencies by a vibration testing system. The results revealed that the natural frequency of the MRE absorber working in squeeze mode can be tuned from 37 Hz to 67 Hz. Following this, a theoretical model based on magnetic dipole theory was developed to investigate the dynamic performance of the squeeze MRE absorber, and the vibration attenuation of the squeeze MRE absorber was then verified by mounting it on a beam with supports under both ends. The results revealed that the squeeze MRE absorber extended its vibration attenuation range from 37 Hz to 67 Hz while the passive absorber was only effective around 53 Hz.

BACKGROUND: The effect of general anesthetics (propofol and volatile anesthetics) on pulmonary outcome after lung resection surgery with one-lung ventilation (OLV) is yet undetermined. We evaluated the effect of intravenous anesthesia (propofol) and volatile anesthesia (sevoflurane or desflurane) regimens on postoperative pulmonary complications (PPCs) in patients undergoing lung resection surgery. METHODS: This prospective, randomized controlled trial enrolled 555 adult patients scheduled for lung resection surgery with OLV. Participants were randomized to 1 of 3 general anesthetic regimens (propofol, sevoflurane, or desflurane). Standard anesthesia and ventilation protocols were followed in all groups. The primary outcome was a composite of PPCs in the first 7 postoperative days. Secondary outcomes included the severity of PPCs and major postoperative complications classification. Intergroup difference in the primary outcome was assessed for significance using the Pearson χ2 test. RESULTS: Of 837 patients who were assessed for eligibility, 555 were randomized and 545 were analyzed. One hundred and seventy-nine patients were assigned to the propofol group, 182 in the sevoflurane group, and 184 in the desflurane group. The incidence of PPCs did not differ between the combined volatile anesthetics (sevoflurane and desflurane) group and the propofol group (21.9% vs 24.0%; odds ratio, 0.89; 95% confidence interval, 0.58-1.35; P = .570). The PPCs grade and Clavien-Dindo scores did not differ significantly across groups. CONCLUSIONS: In patients undergoing lung resection surgery with OLV, general anesthesia with volatile anesthetics (sevoflurane or desflurane) did not reduce PPCs compared with propofol. No difference in secondary outcomes was observed.

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