硒是人体必需的微量营养元素之一, 我国1/3的地区严重缺硒. 植物通过自身的新陈代谢作用,可以将无机硒转化为生物活性高、更安全的有机硒,利用富硒的水果、蔬菜、稻米等农产品的摄入来补硒是最安全有效的途径[1,2]. 水培是一种新型的蔬菜栽培方式,具有高效、清洁、一致性高、可控性强等优点[3].以迷你型温室水耕床(专利号:ZL201320519728.6)为例,介绍一种速生叶菜富硒水培生产的床架结构、育苗定植、施硒、采收等相关栽培技术.

Optical and thermal metamaterials-based devices have been extensively explored under the guidance of transformation optics/thermotics theories to tune light and heat propagation to realize unprecedented functions, such as cloaking, concentrating, camouflaging, etc. Other than these functions, what else can they do? In this paper, we demonstrate another interesting and potential application, thermal encoding, based on the thermal energy shielding and harvesting units. The proposed thermal encoding protocol takes advantage of the binary (contrary) states of heat flux through two units, which can be encoded as binary digits of 1 and 0, respectively. Steady and transient simulations and experiments validate the feasibility of thermal encoding, which can be further effectively encrypted depending on the encoding or decoding protocol. Such thermal encoding supplements the existing implementations of thermal memory or computing. The proposed encoding protocol may open an alternative avenue for triggering counterpart developments by utilizing the binary states of electromagnetic and optical metamaterials for information encoding, decoding, and storage.

Invisible optical and thermal cloaking have been explored as the typical demonstrations of the transformation optics and thermotics theory. However, the existing cloaks are realized by only one-coordinate transformation, and the cloaking layout, i.e. the form of electromagnetic wave/heat passing around the invisible region, is single for a long time. Here, we propose a new rotated thermal cloak which can unify the conventional cloaking and rotating together, and realize the while-rotating–while-cloaking effect. The required anisotropic thermal conductivity tensor is deduced from the new geometric mapping. Though rotated, the heat flux can be tuned around the central invisible region perfectly by the proposed rotated thermal cloak. The underlying physics is explored by comprehensive analysis of the distribution of the thermal conductivity tensor, which is further compared with those of the conventional cloak and rotator. The experimental feasibility is also discussed by validating the practical while-rotating–while-cloaking effect through a proof-of-concept design. The proposed rotated thermal cloak is expected to extend the possibility of cloaking scheme, and open avenues for the multiple coordinate transformation in counterpart physical fields, like optics, electrics, acoustics, magnetics, mechanics, etc.

Metamaterials have attracted sufficient attentions in exploring new phenomena and functions, improving performance and efficiency, and extending to other physical fields. But how to detect the metamaterial structures is still lacking though it is significantly demanded in imaging analysis or military application. Here, we successfully attempt this problem by flying laser point to detect the edge of the thermal metamaterial structures. The ideal thermal cloak, concentrator and rotator are taken as examples with brief introduction of the design process. The dynamic hot spot behaviors, corresponding to the evanescent dissipation of thermal energy, of the flying laser point are analyzed with full description of the specific features and successful identification of the three thermal structures on the plane. The proposed method can be used for edge detection, and help developing some transient imaging analyzer or anti-function structures.