Osteogenesis is a complex series of events involving the differentiation of mesenchymal stem cells to generate new bone. In this study, we examined the effect of pulsed electromagnetic fields (PEMFs) on cell proliferation, alkaline phosphatase (ALP) activity, mineralization of the extracellular matrix, and gene expression in bone marrow mesenchymal stem cells (BMMSCs) during osteogenic differentiation. Exposure of BMMSCs to PEMFs increased cell proliferation by 29.6% compared to untreated cells at day 1 of differentiation. Semi-quantitative RT-PCR indicated that PEMFs significantly altered temporal expression of osteogenesis-related genes, including a 2.7-fold increase in expression of the key osteogenesis regulatory gene cbfa1, compared to untreated controls. In addition, exposure to PEMFs significantly increased ALP expression during the early stages of osteogenesis and substantially enhanced mineralization near the midpoint of osteogenesis. These results suggest that PEMFs enhance early cell proliferation in BMMSC-mediated osteogenesis, and accelerate the osteogenesis.

This study proposed a new semiactive control device for building control. Semiactive tuned mass damper (STMD) combine a tradition tuned mass damper (TMD) and a semiactive damper. The property of semiactive damper can be adjusted online to produce the desired control force. In the present year, many types of semiactive dampers are proposed. In this study, the variable damping device and MR damper are used to illustrate the control effect of STMD. In addition, the control effect of the TMD and active tuned mass damper are also compared. The numerical simulation results show that the STMD can greatly improve the control efficiency of TMD.

Aim: To investigate the role of hTERT gene expression and AP-2α in n-butylidenephthalide (n-BP)-induced apoptosis in A549 lung cancer cells. Methods: Viability of A549 cells was measured by MTT assay. Protein expression was determined by Western blot. Telomerase activity was measured using the modified telomere repeat amplification protocol (TRAP) assay. Xenograft mice were used as a model system to study the cytotoxic effect of n-BP in vivo. The morphology of tumor was examined by immunohistochemical staining. Results: The growth of A549 lung cancer cells treated with n-BP was significantly inhibited. Telomerase activity and hTERT mRNA expression were determined by telomeric repeat amplification protocol and reverse transcription-polymerase chain reaction, respectively. n-BP inhibited telomerase activity and hTERT mRNA expression in A549 cells while overexpression of hTERT could abolish BPinduced growth inhibition in the A549 cells. We also showed that hTERT promoter activity in the presence of n-BP was mediated via AP-2α. We saw an inhibition of tumor growth when nude mice carrying A549 subcutaneous xenograft tumors were treated with n-BP. Immunohistochemistry of this tumor tissue also showed a decrease in the expression of hTERT. Conclusion: The antiproliferative effects of n-BP on A549 cells in vitro and in vivo suggest a novel clinical application of this compound in the treatment of lung cancers.

SUMMARYExperimental techniques for testing dynamically substructured systems are currently receiving attention in a wide range of structural, aerospace and automotive engineering environments. Dynamic substructuring enables full-size, critical components to be physically tested within a laboratory (as physical substructures), while the remaining parts are simulated in real-time (as numerical substructures). High quality control is required to achieve synchronization of variables at the substructuring interfaces and to compensate for additional actuator system(s) dynamics, nonlinearities, uncertainties and time-varying parameters within the physical substructures. This paper presents the substructuring approach and associated controller designs for performance testing of an aseismic, base-isolation system, which is comprised of roller-pendulum isolators and controllable, nonlinear magnetorheological dampers. Roller-pendulum isolators are typically mounted between the protected structure and its foundation and have a fundamental period of oscillation far-removed from the predominant periods of any earthquake. Such semi-active damper systems can ensure safety and performance requirements, whereas the implementation of purely active systems can be problematic in this respect. A linear inverse dynamics compensation and an adaptive controller are tailored for the resulting nonlinear synchronization problem. Implementation results favourably compare the effectiveness of the adaptive substructuring method against a conventional shaking-table technique. A 1.32% error resulted compared with the shaking-table response. Ultimately, the accuracy of the substructuring method compared with the response of the shaking-table is dependent upon the fidelity of the numerical substructure.

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Damping systems discussed in this work are optimized so that a three-story steel frame structure and its SMA bracing system minimize response metrics due to a customtailored earthquake excitation. Multiple-objective numerical optimization that simultaneously minimizes displacements and accelerations of the structure is carried out with a genetic algorithm (GA) in order to optimize SMA bracing elements within the structure. After design of an optimal SMA damping system is complete, full-scale experimental shake table tests are conducted on a large-scale steel frame that is equipped with the optimal SMA devices. A fuzzy inference system is developed from data collected during the testing to simulate the dynamic material response of the SMA bracing subcomponents. Finally, nonlinear analyses of a three-story braced frame are carried out to evaluate the performance of comparable SMA and commonly-used steel braces under dynamic loading conditions and to assess effectiveness of GA-optimized SMA bracing design as compared to alternative designs of SMA braces. It is shown that peak displacement of a structure can be reduced without causing significant acceleration response amplification through a judicious selection of physical characteristics of the SMA devices. Also, SMA devices provide a re-centering mechanism for the structure to return to its original position after a seismic event.

Because of many advantages over other control systems, semi-active control devices have received considerable attention for applications to civil infrastructures. A variety of different semi-active control devices have been studied for applications to buildings and bridges subject to strong winds and earthquakes. Recently, a new semi-active control device, referred to as the resetable semi-active stiffness damper (RSASD), has been proposed and studied at the University of California, Irvine (UCI). It has been demonstrated by simulation results that such a RSASD is quite effective in protecting civil engineering structures against earthquakes, including detrimental near-field earthquakes. In this paper, full-scale hardware for RSASD is designed and manufactured using pressurized gas. Experimental tests on full-scale RSASDs have been conducted to verify the hysteretic behaviours (energy dissipation characteristics) and the relation between the damper stiffness and the gas pressure. The correlation between the experimental results of the hysteresis loops of RASADs and that of the theoretical ones has been assessed qualitatively. Experimental results further show the linear relation between the gas pressure and the stiffness of the RSASD as theoretically predicted. Finally, shake table tests have also been conducted using an almost full-scale 3-storey steel frame model equipped with full-scale RSASDs at the National Center for Research on Earthquake Engineering (NCREE), Taipei, Taiwan, and the results are presented. Experimental results demonstrate the performance of RSASDs in reducing the responses of the large-scale building model subject to several near-field earthquakes.