Radiative metamaterials based on effective-medium theory

Thermal metamaterials have made significant advancements in the past few decades. However, the concept of thermal metamaterials is primarily rooted in the thermal conduction mechanism, which has consequently restricted their application scope. It is imperative to consider thermal radiation, another crucial thermal transport mechanism, particularly in high-temperature regimes, when designing thermal devices. In this review paper, we present the advancements in this area, with a specific focus on research conducted using the effective-medium theory. Additionally, we explore the potential applications of radiative thermal metamaterials and discuss prospective research directions from a microscopic perspective for future investigations

Diffusive Pseudo-Conformal Mapping: Anisotropy-Free Transformation Thermal Media with Perfect Interface Matching

Transformation media provide a fundamental paradigm for field regulation, but their tricky anisotropy challenges fabrication. Though optical conformal mapping has been utilized to eliminate anisotropy, two key factors still hinder its development in thermotics, i.e., the distinct diffusion nature and inevitable interface mismatching. Here, we put forth the concept of diffusive pseudo-conformal mapping, overcoming the inherent difference between diffusion and waves and achieving perfect interface matching. The proposed mapping directly leads to heat guiding and expanding functions with anisotropy-free transformation thermal media, whose feasibility is confirmed by experiments or simulations. Besides diverse applications, we provide a unified perspective for two distinct types of prevailing bilayer cloaks by uncovering their profound ties with pseudo-conformal mapping. These results greatly simplify the preparation of transformation thermotics and have implications for regulating other diffusion and wave phenomena

Reconfigurable Three-Dimensional Thermal Dome

Thermal metamaterial represents a groundbreaking approach to control heat conduction, and, as a crucial component, thermal invisibility is of utmost importance for heat management. Despite the flourishing development of thermal invisibility schemes, they still face two limitations in practical applications. First, objects are typically completely enclosed in traditional cloaks, making them difficult to use and unsuitable for objects with heat sources. Second, although some theoretical proposals have been put forth to change the thermal conductivity of materials to achieve dynamic invisibility, their designs are complex and rigid, making them unsuitable for large-scale use in real three-dimensional spaces. Here, we propose a concept of a thermal dome to achieve three-dimensional invisibility. Our scheme includes an open functional area, greatly enhancing its usability and applicability. It features a reconfigurable structure, constructed with simple isotropic natural materials, making it suitable for dynamic requirements. The performance of our reconfigurable thermal dome has been confirmed through simulations and experiments, consistent with the theory. The introduction of this concept can greatly advance the development of thermal invisibility technology from theory to engineering and provide inspiration for other physical domains, such as direct current electric fields and magnetic fields

Research on household emergency supplies storage from the theory of planned behavior and intention-behavior gap in the context of COVID-19

IntroductionIn the context of COVID-19 epidemic, household-level emergency supplies are becoming a critical link in the national emergency response mechanism for public health emergencies. The main goal of this study is to analyze the forming process of household emergency supplies storage intention and behavior based on the theory of planned behavior.MethodsA total of 486 valid questionnaires were obtained from China and analyzed using structural equation modeling.ResultsThe study found that subjective norms and perceived behavioral control had a positive impact on residents’ intention to store emergency supplies, while attitudes did not play a significant role. Community institutional trust and community network play significant moderating roles in the transformation from intentions to behaviors.DiscussionThis study explored the influencing factors of residents’ household emergency supplies storage, and introduced community institutional trust and community network as moderating variables to analyze the process of transformation of residents’ household emergency supplies storage intentions to behaviors from the perspective of community situation, and initially constructed a two-stage integration model including intention formation and behavior transformation. By analyzing the forming process of household emergency supplies behavior, this paper revealed the effective paths for the formation of household emergency supplies storage intention, and put forward policy suggestions from the government and community levels

Controlling mass and energy diffusion with metamaterials

Diffusion driven by temperature or concentration gradients is a fundamental mechanism of energy and mass transport, which inherently differs from wave propagation in both physical foundations and application prospects. Compared with conventional schemes, metamaterials provide an unprecedented potential for governing diffusion processes, based on emerging theories like the transformation and the scattering cancellation theory, which enormously expanded the original concepts and suggest innovative metamaterial-based devices. We hereby use the term ``diffusionics'' to generalize these remarkable achievements in various energy (e.g., heat) and mass (e.g., particles and plasmas) diffusion systems. For clarity, we categorize the numerous studies appeared during the last decade by diffusion field (i.e., heat, particles, and plasmas) and discuss them from three different perspectives: the theoretical perspective, to detail how the transformation principle is applied to each diffusion field; the application perspective, to introduce various intriguing metamaterial-based devices, such as cloaks and radiative coolers; and the physics perspective, to connect with concepts of recent concern, such as non-Hermitian topology, nonreciprocal transport, and spatiotemporal modulation. We also discuss the possibility of controlling diffusion processes beyond metamaterials. Finally, we point out several future directions for diffusion metamaterial research, including the integration with artificial intelligence and topology concepts.Comment: This review article has been accepted for publication in Rev. Mod. Phy

PCBP-1 regulates alternative splicing of the CD44 gene and inhibits invasion in human hepatoma cell line HepG2 cells

<p>Abstract</p> <p>Background</p> <p>PCBP1 (or alpha CP1 or hnRNP E1), a member of the PCBP family, is widely expressed in many human tissues and involved in regulation of transcription, transportation process, and function of RNA molecules. However, the role of PCBP1 in CD44 variants splicing still remains elusive.</p> <p>Results</p> <p>We found that enforced PCBP1 expression inhibited CD44 variants expression including v3, v5, v6, v8, and v10 in HepG2 cells, and knockdown of endogenous PCBP1 induced these variants splicing. Invasion assay suggested that PCBP1 played a negative role in tumor invasion and re-expression of v6 partly reversed the inhibition effect by PCBP1. A correlation of PCBP1 down-regulation and v6 up-regulation was detected in primary HCC tissues.</p> <p>Conclusions</p> <p>We first characterized PCBP1 as a negative regulator of CD44 variants splicing in HepG2 cells, and loss of PCBP1 in human hepatic tumor contributes to the formation of a metastatic phenotype.</p

Electrostatic chameleons: theory of intelligent metashells with adaptive response to inside objects

The remarkable capability to tailor material property has largely expanded the permittivity range, even with negative value. However, permittivity, as an inherent property, may lack adaptive response to nearby objects. To solve this problem, here we introduce the chameleon behavior from biology to electrostatics. The essence of electrostatic chameleons can be concluded as intelligent metashells with adaptive response to inside objects. The requirement of electrostatic chameleons is deduced by making the effective permittivities of metashells only dependent on the permittivities of inside objects. By delicately designing the anisotropic permittivities of metashells, we summarize two types of electrostatic chameleons with distinct mechanisms. The theoretical analyses are validated by numerical simulations, which indicate that the proposed metashells do work as expected. Such schemes have potential applications in camouflage, self-adaption, etc. This work not only lays the theoretical foundation for electrostatic chameleons, but also provides guidance for exploring other intelligent materials beyond chameleon

Thermal illusion with the concept of equivalent thermal dipole

The research on thermal illusion contributes to both fundamental theories and practical applications. In the existing literatures, the most common mechanism is to design a shell to disguise the inside core. However, the core-shell scheme may be weak to handle many-particle systems because N particles may require N specially-designed shells. This lacks efficiency and restricts practical applications. To solve this problem, we can no longer focus on the local effect of a single particle. In contrast, we should study the macroscopic effect of the N particles by treating each particle as an equivalent thermal dipole. Then, thermal illusion can be achieved when the macroscopic equivalent thermal dipole moments of different systems are equal to each other. This requires only once calculation and contributes to efficiency. Accidentally, the concept of equivalent thermal dipole helps to revisit the well-known Bruggeman theory and provides a clear physical image for it. The proposed scheme is verified by theoretical analyses, finite-element simulations, and laboratory experiments. Our work offers an efficient approach to achieving thermal illusion in many-particle systems, and contributes to potential applications in misleading infrared detection, manipulating heat flux, etc