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There exists a lot of research on the nonlinear vibration of the pipeline system with different boundary conditions. To the best of our knowledge, little research on the actual constraint of the clamp has been performed. In this paper, according to hysteresis loops of the clamp obtained from experimental test, the simplified bilinear stiffness and damping model is proposed. Then the Finite Element (FE) model of L-type pipeline system with clamps is established using Timoshenko beam theory in combination with aforementioned stiffness-damping model. Both hammering and shaker tests verify the FE model via the comparisons of natural frequencies and vibration responses. The results show that the maximum errors of natural frequencies and vibration responses are about 8.31% and 17.6%, respectively. The proposed model can simulate the dynamic characteristics of the L-type pipeline system with clamps well, which is helpful to provide some guidance for the early design stage of pipeline in aero-engine.

The production of excess free zinc ions (Zn

Hypoxia, induced by inadequate oxygen supply, is a key indication of various major illnesses, which necessitates the need to develop new nanoprobes capable of sensing hypoxia environments for the targeted system monitoring and drug delivery. Herein, we report a hypoxia-responsive, periodic mesoporous organosilica (PMO) nanocarrier for repairing hypoxia damage. β-cyclodextrin (β-CD) capped azobenzene functionalization on the PMO surface could be effectively cleaved by azoreductase under a hypoxia environment. Moreover, the nanosystem is equipped with fluorescence resonance energy transfer (FRET) pair (tetrastyrene derivative (TPE) covalently attached to the PMO framework as the donor and Rhodamine B (RhB) in the mesopores as the receptor) for intracellular visualization and tracking of drug release in real-time. The design of intelligent nanocarriers capable of simultaneous reporting and treating of hypoxia conditions highlights a great potential in the biomedical domain.

This paper presents a general approach for free vibration analysis of spinning local elastic-foundation supported joined conical–cylindrical shells (JCCSs) with arbitrary boundary conditions. The Donnell’s shell theory is employed in the modeling of the structures, and all the effects of centrifugal forces, Coriolis forces as well as initial hoop tensions are considered. The approach utilizes the concept of artificial springs which permit convenient joining of the conical and cylindrical shells. Particularly, it can efficiently simulate arbitrary boundary conditions of JCCSs. The spinning JCCSs are locally or completely surrounded by elastic foundation, formulated by the Pasternak model. By using the orthogonal polynomial series as the admissible functions, the frequency equations of spinning JCCSs with arbitrary boundary conditions are derived using the Rayleigh–Ritz method. Then, some numerical examples are compared with the available literature and finite element results to validate the present approach. Finally, the effects of key parameters on free vibration characteristics are investigated including spring stiffness, spinning speed, cone angle and local elastic foundation.

In the present study, the effect of plant growth regulators (PGRs) on callus regeneration, adventitious shoot differentiation, and root formation of Haworthia turgida Haw. was investigated. The greatest callus induction percentage (95.6%) was achieved with leaf explants inoculated on Murashige and Skoog (MS) medium with 1.0 mg·L−1 6-benzyladenine (BA) and 0.1 mg·L−1 1-naphthaleneacetic acid (NAA), and this callus induction medium supplemented with 2.5 mg·L−1 thidiazuron (TDZ) was optimal for callus proliferation. The maximum number of shoots (25.7) was obtained when the callus was cultured on MS medium supplemented with 1.0 mg·L−1 BA and 0.2 mg·L−1 2,4-dichlorophenoxyacetic acid (2,4-D). The highest number of roots per shoot (6.2) and highest rooting frequency (82.0%) were obtained when adventitious shoots were inoculated on MS medium with 0.05 mg·L−1 NAA. Regenerated plantlets were transferred to a mixture of vermiculite and soil and acclimated in a greenhouse. The survival rate of the transplanted plantlets was about 91.6%. The rate of ex vitro rooting was 83.3%, indicating that this technique is effective for root induction in H. turgida. This study has established a rapid and efficient micropropagation system that can be beneficial for commercial cultivation and germplasm conservation of H. turgida.