| 1 | Macroscopic and microscopic mechanical behaviors of climbing tendrils显示文摘Tendril-bearing climbing plants must recur to the tendril helices with chiral perversion or dual chirality for climbing and to obtain sun exposure. Despite researchers' prolonged fascination with climbing tendrils since Darwin's time and even earlier, why the soft and slender tendrils can bear heavy loads such as the self-weight of a plant or additional load caused by rain remains elusive. In this paper, we take towel gourd tendrils as an example and investigate the macroscopic and microscopic mechanical behaviors of tendrils through experiments and simulations. Our study indicates that the tendril filament exhibits rubber-like hyperelastic behaviors and can particularly endure large elongation, which is mainly attributed to the superelasticity of the cellulose fibril helix contained in the cell wall. Combination of the tendril helical structure with dual chirality or chiral perversion at a macroscale and a cellulose filament helix at a subcellular level creates superior elasticity for biological species relying on support and climbing. This study provides deep insight into the structure-property relationship of climbing tendrils, and the relationship is useful for the bioinspired design of composite systems with superior elasticity. | Q.Guo J.J.Dong Y.Liu X.H.Xu Q.H.Qin J.S.Wang | 2019 | Acta Mechanica Sinica2019，35，3： | 1 |
| 2 | Proton beams from intense laser-solid interaction:Effects of the target materials显示文摘We report systematic studies of laser-driven proton beams produced with micrometer-thick solid targets made of aluminum and plastic,respectively.Distinct effects of the target materials are found on the total charge,cutoff energy,and beam spot of protons in the experiments,and these are described well by two-dimensional particle-in-cell simulations incorporating intrinsic material properties.It is found that with a laser intensity of 8×10^(19) W/cm^(2),target normal sheath acceleration is the dominant mechanism for both types of target.For a plastic target,the higher charge and cutoff energy of the protons are due to the greater energy coupling efficiencies from the intense laser beams,and the larger divergence angle of the protons is due to the deflection of hot electrons during transport in the targets.We also find that the energy loss of hot electrons in targets of different thickness has a significant effect on the proton cutoff energy.The consistent results obtained here further narrow the gap between simulations and experiments. | Y.X.Geng D.Wu W.Yu Z.M.Sheng S.Fritzsche Q.Liao M.J.Wu X.H.Xu D.Y.Li W.J.Ma H.Y.Lu Y.Y.Zhao X.T.He J.E.Chen C.Lin X.Q.Yan | 2020 | Matter and Radiation at Extremes2020，5，6： | 0 |
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