The chiral phase transition in charge ordered 1T-TiSe2

It was recently discovered that the low temperature, charge ordered phase of 1T-TiSe2 has a chiral character. This unexpected chirality in a system described by a scalar order parameter could be explained in a model where the emergence of relative phase shifts between three charge density wave components breaks the inversion symmetry of the lattice. Here, we present experimental evidence for the sequence of phase transitions predicted by that theory, going from disorder to non-chiral and finally to chiral charge order. Employing X-ray diffraction, specific heat, and electrical transport measurements, we find that a novel phase transition occurs ~7 K below the main charge ordering transition in TiSe2, in agreement with the predicted hierarchy of charge ordered phases.Comment: 5 pages, 3 figures; includes additional experimental and theoretical results; fixed typo

A review of aerodynamic and wake characteristics of floating offshore wind turbines

International audienceWind-generated electricity has effectively promoted the net-zero carbon emission plan, and gradually developed to the deeper ocean, which leads to the emergence of rotating equipment with both rigidity and flexibility: floating offshore wind turbines (FOWT). This review presents crucial determinants for the FOWT's power generation, namely aerodynamics and wakes, which are strongly coupled to the hydrodynamics of the floating platform. The selection of different platforms leads to unique performances, and technology and cost are direct constraints for global floating projects. In the experimental study, the scale model based on some similarity criteria is used to reflect aerodynamic characteristics of the prototype under the multi-degree of freedom motions, but with the contradiction between the Froude number and Reynolds number. Wave basin and wind tunnel are two typical research forms, but the premise is the model scaling to obtain similar dynamic thrust and power. Besides, a cyclic pitch control method is discussed, which is expected to effectively reduce the fatigue load of the spindle and gears. As for the numerical simulation, Blade Element Momentum, Computational Fluid Dynamics, Free-Vortex Wake and Boundary Element behave in different calculation capacities and costs. The power, thrust and wake are obtained under specific platform and motion conditions, and the calculation results lack comparisons and verifications. It is necessary to ignore the extremely limited power increase caused by pitch and surge motion in the design process, to make the platform more stable for dynamic performances and significantly reduce fatigue loads. As a review article, this paper could provide a meaningful reference for those engaged in the aerodynamics of FOWT

The coupling of multi-channel optical vortices based on angular momentum conservation using a single-layer metal metasurface

Optical vortices (OVs) carry the orbital angular momentum with arbitrary topological charges, which has excellent potential in optical communication, photonic integrated circuits, optical trapping, and so on. However, generating arbitrary orders of adjustable optical vortices remains to be solved. Here, we propose a single-layer metal porous metasurface operating in infrared band for generating vortex beams from first to fourth order based on the spin-orbit interactions (SOI). The optical vortices with integral 2π phase are obtained through generating double geometric phase induced by structural element spin rotation. Furthermore, the new phenomenon of optical vortices emerging on the center has also been observed in our system, which is caused by the coupling of multi-channel same-order OVs. Our work possesses wide applications in optical communication, multiplex and demultiplex systems, optical capture devices, and communication coding

Chinese Knot Inspired Ag Nanowire Membrane for Robust Separation in Water Remediation

Chinese knot is a "traditional handicraft art" in Chinese culture, which is expected to ward off evil spirits and pray for good luck. It is constructed by weaving cords and tying different types of knots firmly. Inspired by Chinese knot, a robust 1D Ag nanowire membrane with nanoscale knots is fabricated to achieve robust catalytic/anti-bacterial separation. Silver mirror reaction is manipulated to anchor Ag nanowires on a hierarchical polyvinylidene fluoride membrane substrate. The robust Ag nanowire membrane withstands the vigorous cross-flow hydraulic shear (3000 mL min(-1)) for 24 h at 0.1 MPa without any physicochemical deterioration. The Chinese knot inspired membrane exhibits extraordinary robustness in continuous catalysis, kill-release anti-bacteria, oil-in-water emulsion, and ultrafiltration separation. This work paves a new way for constructing a robust 1D inorganic nanowire membrane for water remediation applications

Chinese Knot Inspired Ag Nanowire Membrane for Robust Separation in Water Remediation

Chinese knot is a "traditional handicraft art" in Chinese culture, which is expected to ward off evil spirits and pray for good luck. It is constructed by weaving cords and tying different types of knots firmly. Inspired by Chinese knot, a robust 1D Ag nanowire membrane with nanoscale knots is fabricated to achieve robust catalytic/anti-bacterial separation. Silver mirror reaction is manipulated to anchor Ag nanowires on a hierarchical polyvinylidene fluoride membrane substrate. The robust Ag nanowire membrane withstands the vigorous cross-flow hydraulic shear (3000 mL min(-1)) for 24 h at 0.1 MPa without any physicochemical deterioration. The Chinese knot inspired membrane exhibits extraordinary robustness in continuous catalysis, kill-release anti-bacteria, oil-in-water emulsion, and ultrafiltration separation. This work paves a new way for constructing a robust 1D inorganic nanowire membrane for water remediation applications