As constitutive models are too complicated and existing mechanical models lack universality, these models are beyond satisfaction for magnetorheological elastomer (MRE) devices. In this article, a novel universal method is proposed to build concise mechanical models. Constitutive model and electromagnetic analysis were applied in this method to ensure universality, while a series of derivations and simplifications were carried out to obtain a concise formulation. To illustrate the proposed modeling method, a conical MRE isolator was introduced. Its basic mechanical equations were built based on equilibrium, deformation compatibility, constitutive equations and electromagnetic analysis. An iteration model and a highly efficient differential equation editor based model were then derived to solve the basic mechanical equations. The final simplified mechanical equations were obtained by re-fitting the simulations with a novel optimal algorithm. In the end, verification test of the isolator has proved the accuracy of the derived mechanical model and the modeling method.

With the rapidly increasing number of long span bridges being built all over the world, the windinduced vibrations of their constructing high bridge towers are becoming a serious issue. These vibrations will discomfort workers, affect construction accuracy, lead to construction period delay, and sometimes even cause accidents. Tuned mass dampers (TMDs) are well accepted to have a good performance in wind-induced vibration control under the condition that their natural frequencies are tuned to the natural frequencies of the main structures. However, as the natural frequencies of the bridge towers keep varying during its construction, their wind-induced vibrations can hardly be controlled by conventional TMDs. To improve the control efficiency, a novel magnetorheological elastomer variable stiffness tuned mass damper (MRE VSTMD) was proposed to retune the system. To verify the efficiency of the proposed system, a constructing bridge tower was modeled analytically and the corresponding MRE VSTMD was designed. Simulations were carried out and evaluations were made among the uncontrolled, passive controlled and semi-active controlled structures. It is proved that the proposed MRE VSTMD can improve the performance of passive TMDs by up to 40%. It is also observed that the softening behavior can double the stiffness variable range of MRE layers, indicating MRE VSTMD's potential to further improve its performance with time varying excitation powers.

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Here, we report the first asymmetric total synthesis of (+)-talassimidine and (+)-talassamine, two hetidine-type C20-diterpenoid alkaloids. A highly regio- and diastereoselective 1,3-dipolar cycloaddition of an azomethine ylide yielded a chiral tetracyclic intermediate in high enantiopurity, thus providing the structural basis for asymmetric assembly of the hexacyclic hetidine skeleton. In this key step, the introduction of a single chiral center induces four new continuous chiral centers. Another key transformation is the dearomative cyclopropanation of the benzene ring and subsequent SN2-like ring opening of the resultant cyclopropane ring with water as a nucleophile, which not only establishes the B ring but also precisely installs the difficult-to-achieve equatorial C7–OH group.

In this paper, we described the synthesis and characterization of new diphenylethylene bearing imino group. We concentrated particularly on the investigation of the possibility of the excited state intramolecular charge transfer (ESIPT) of the new dyes experimentally and theoretically. The absorption and fluorescence spectroscopy of the dyes were determined in various solvents. The results showed that the maximal absorption wavelength of 2-[(4'-N,N-dimethylamino-diphenylethylene-4-ylimino)methyl]phenol (C1) and 4-[(4'-N,N-dimethylamino-diphenylethylene-4-ylimino)methyl]phenol (C2) exhibited almost independence on the solvent polarity. While as contrast, the maximal fluorescence wavelength of the dyes showed somewhat dependence on the solvent polarity. In particular, C1 displayed well-separated dual fluorescence spectroscopy. The second fluorescence peak was characterized with an "abnormal" fluorescence emission wavelength in aprotic solvents with large Stokes shift (ca. 140 nm in THF), which was much more than normal Stokes shift (ca. 30 nm in THF). This emission spectroscopy could be assigned to ESIPT emission. On the other hand, the ESIPT fluorescence of C1 was much reduced or lost in the protic solvents. While, only normal fluorescence emission was detected in various solvents. Although the absorption maxima of C1 exhibited about 10 nm red-shift with respect to those of C2, the normal fluorescence maxima of C1 and C2 were almost identical in various solvents. These results suggested that C1 could undergo ESIPT, but C2 was not able to proceed ESIPT. The molecular geometry optimization of phototautomers in the ground electronic state (S 0 ) was carried out with HF method (Hartree-Fock) and at DFT level (Density Functional Theory) using B3LYP both, while the CIS was employed to optimize the geometries of the first singlet excited state (S 1 ) of the phototautomers of C1 and C2 respectively. The properties of the ground state and the excited state of the phototautomers of C1 and C2, including the geometrical parameter, the energy, the frontier orbits, the Mulliken charge and the dipole moment change were performed and compared completely. The data were analyzed further based on our experimental results. Furthermore, the absorption and fluorescence spectra were calculated in theory and compared with the measured ones. The rate constant of internal proton transfer (9.831×10 11 s -1 ) of C1 was much lower than that of salicylidene methylamine (C3, 2.045×10 15 s -1 ), which was a typical Schiff base compound and was well demonstrated to undergo ESIPT easily under photoexcitation.