Chiral structures play an important role in natural sciences due to their great variety and potential applications. A perversion connecting two helices with opposite chirality creates a dual-chirality helical structure. In this paper, we develop a novel model to explore quantitatively the mechanical behavior of normal, binormal and transversely isotropic helical structures with dual chirality and apply these ideas to known nanostructures. It is found that both direction and amplitude of rotation can be finely controlled by designing the cross-sectional shape. A peculiar rotational inversion of overwinding followed by unwinding, observed in some gourd and cucumber tendril perversions, not only exists in transversely isotropic dual-chirality helical nanobelts, but also in the binormal/normal ones when the cross-sectional aspect ratio is close to 1. Beyond this rotational inversion region, the binormal and normal dual-chirality helical nanobelts exhibit a fixed directional rotation of unwinding and overwinding, respectively. Moreover, in the binormal case, the rotation of these helical nanobelts is nearly linear, which is promising as a possible design for linear-to-rotary motion converters. The present work suggests new designs for nanoscale devices.

中文翻译：

---

具有双手性的纳米结构中可控的旋转反转†

由于手性结构的多样性和潜在的应用前景，它们在自然科学中起着重要的作用。连接两个具有相反手征性的螺旋的变态产生了双手征性的螺旋结构。在本文中，我们开发了一个新颖的模型，以定量探索具有双手性的正态，双正态和横向各向同性螺旋结构的力学行为，并将这些思想应用于已知的纳米结构。发现通过设计横截面形状可以很好地控制旋转的方向和幅度。在某些葫芦和黄瓜卷须变态中观察到的一种特殊的旋转过度上紧接着倒退的现象，不仅存在于横观各向同性的双手性螺旋纳米带中，而且在横截面纵横比接近1的双正态/正态螺旋纳米带中也存在。 。除了该旋转反转区域之外，双正态和正常双手性螺旋纳米带分别表现出固定的绕卷和绕卷的旋转方向。而且，在双正常情况下，这些螺旋纳米带的旋转几乎是线性的，这有望作为线性转旋转运动转换器的一种可能的设计。目前的工作提出了纳米器件的新设计。