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High temperatures cause thermal stress, impair plant physiology, and reduce crop yield. In a recent publication in Nexus, Wang et al. describe a radiative cooling mulch for soil cooling. This technique increases crop yield in hot climates by alleviating thermal stress on plant roots and reducing soil evaporation, facilitating sustainable agriculture in regions prone to thermal stress.

Passive daytime radiative cooling has emerged as a promising sustainable technique for meeting ever-growing demand for cooling across multiple sectors. Although a number of review articles have reported fundamental mechanisms and materials developments of daytime radiative cooling, reviews on its current and potential applications have been limited to specific scenarios such as building energy saving. Thus, to the best of our knowledge, here we summarize and discuss a comprehensive list of most current and potential applications of passive daytime radiative cooling to broaden horizons in this technology. First, from a materials perspective, we briefly summarize approaches to creating high solar reflectance and high emissivity in the atmospheric window of 8–13 µm. We then present applications in five major categories, each with several sub-categories, and discus each application with selective articles. Based on the availability of real-world demonstrations and developments in commercialization, we qualitatively assess the technology readiness levels of these applications, highlighting future directions that need more attention. This review offers one-stop access to a comprehensive summary of passive radiative cooling applications along with recent progress and future opportunities.

Real-world applications of radiative sky cooling require thoughtful design of the system, along with clear understanding of weather effects on system performance. This work explores application of radiative sky cooling based upon a low-cost radiative cooling metamaterial that can be scalably manufactured. A radiative cooled-cold collection (RadiCold) module is developed to cool water to 10.6°C below ambient at noon under stationary conditions. The effects of different weather conditions (wind speed, precipitable water, and cloud cover) on the performance of radiative cooling have been investigated. A kilowatt (kW)-scale RadiCold system with 13.5 m2radiative cooling surface area is then built and demonstrated to provide a maximum cooling power of 1,296 W at night, and an average cooling power of 607 W at noon (12–2 p.m.) under 952 W/m2average solar irradiance at 26.5 L/(h⋅m2) volumetric flow rate. A building-integrated RadiCold system is proposed to provide continuous day-and-night cooling.

Three-dimensional (3D) imaging at the nanoscale is a key to understanding of nanomaterials and complex systems. While scanning probe microscopy (SPM) has been the workhorse of nanoscale metrology, its slow scanning speed by a single probe tip can limit the application of SPM to wide-field imaging of 3D complex nanostructures. Both electron microscopy and optical tomography allow 3D imaging, but are limited to the use in vacuum environment due to electron scattering and to optical resolution in micron scales, respectively. Here we demonstrate plasmonic Brownian microscopy (PBM) as a way to improve the imaging speed of SPM. Unlike photonic force microscopy where a single trapped particle is used for a serial scanning, PBM utilizes a massive number of plasmonic nanoparticles (NPs) under Brownian diffusion in solution to scan in parallel around the unlabeled sample object. The motion of NPs under an evanescent field is three-dimensionally localized to reconstruct the super-resolution topology of 3D dielectric objects. Our method allows high throughput imaging of complex 3D structures over a large field of view, even with internal structures such as cavities that cannot be accessed by conventional mechanical tips in SPM.

Association semantic link (ASL) can provide theoretical support for many web intelligent activities. However, when we extract the keywords-level association semantic link (k-ASL), some sparse distribution k-ASL are easily discarded. To solve this problem, this paper proposes a rapid mining model for extracting sparse distribution k-ASL from large-scale web resources. First, the time validity for three types of k-ASL is analysed to clear their semantic characteristics. Second, three existing problems for mining sparse distribution k-ASL are presented to analyse why this kind of k-ASL is easily discarded. After that, we present the rapid mining theoretical foundation for mining sparse distribution k-ASL. Furthermore, the rapid mining model for extracting sparse distribution k-ASL is proposed, which is based on the presented theory and set computation such as 'difference computation', 'union computation'. At last, the evaluation method is presented and the correctness of the proposed model is validated by experiments.

Electrically controlling the flow of charge carriers is the foundation of modern electronics. By accessing the extra spin degree of freedom (DOF) in electronics, spintronics allows for information processes such as magnetoresistive random-access memory. Recently, atomic membranes of transition metal dichalcogenides (TMDCs) were found to support unequal and distinguishable carrier distribution in different crystal momentum valleys. This valley polarization of carriers enables a new DOF for information processing. A variety of valleytronic devices such as valley filters and valves have been proposed, and optical valley excitation has been observed. However, to realize its potential in electronics it is necessary to electrically control the valley DOF, which has so far remained a significant challenge. Here, we experimentally demonstrate the electrical generation and control of valley polarization. This is achieved through spin injection via a diluted ferromagnetic semiconductor and measured through the helicity of the electroluminescence due to the spin–valley locking in TMDC monolayers. We also report a new scheme of electronic devices that combine both the spin and valley DOFs. Such direct electrical generation and control of valley carriers opens up new dimensions in utilizing both the spin and valley DOFs for next-generation electronics and computing.

Optical spin-Hall effect (OSHE) is a spin-dependent transportation phenomenon of light as an analogy to its counterpart in condensed matter physics. Although being predicted and observed for decades, this effect has recently attracted enormous interests due to the development of metamaterials and metasurfaces, which can provide us tailor-made control of the light-matter interaction and spin-orbit interaction. In parallel to the developments of OSHE, metasurface gives us opportunities to manipulate OSHE in achieving a stronger response, a higher efficiency, a higher resolution, or more degrees of freedom in controlling the wave front. Here, we give an overview of the OSHE based on metasurface-enabled geometric phases in different kinds of configurational spaces and their applications on spin-dependent beam steering, focusing, holograms, structured light generation, and detection. These developments mark the beginning of a new era of spin-enabled optics for future optical components.

Concentrated solar power (CSP) plants are generally located in solar-abundant yet hot and water-stressed locations. In such circumstances, efficient but water-intensive once-through wet cooling and water-free but inefficient air cooling are both unfavorable. Considering both thermal efficiency and water availability/temperature, recirculating evaporative cooling is a better alternative. However, evaporative cooling still loses large amounts of water into the atmosphere and thus requires a nonstop water supply. Therefore, simultaneously reducing water loss and maintaining thermal efficiency requires efficient means of supplemental cooling for CSP plants. Here, following our previous work on scalable radiative cooling films and a kW-scale radiative cooling system (Zhai et al, Science2017; Zhao et al, Joule2019), we explore the potential of consumptive water use reduction in recirculating wet-cooled CSP plants by integrating supplemental radiative cooling and cold storage. Through modeling of a reference CSP plant with a supplemental radiative cooling system as large as the plant solar field, we show that 40 – 60 % of the annual consumptive water use can be potentially reduced in the hot southwestern US region with daytime-only radiative cooling, whereas the annual potential water saving can be as much as 65 – 85 % if the radiative cooling system works both day and night with cold storage.

We propose a one-way invisible cloak using transformation optics of parity-time (PT) symmetric optical materials. At the spontaneous PT-symmetry breaking point, light is scattered only for incidence along one direction since the phase-matching condition is unidirectionally satisfied, making the cloak one-way invisible. Moreover, optical scattering from the one-way cloak can be further engineered to realize more interesting effects, for example, creating a unidirectional optical illusion of the concealed object.

Data communications have been growing at a speed even faster than Moore's Law, with a 44-fold increase expected within the next 10 years. Data Transfer on such scale would have to recruit optical communication technology and inspire new designs of light sources, modulators, and photodetectors. An ideal optical modulator will require high modulation speed, small device footprint and large operating bandwidth. Silicon modulators based on free carrier plasma dispersion effect and compound semiconductors utilizing direct bandgap transition have seen rapid improvement over the past decade. One of the key limitations for using silicon as modulator material is its weak refractive index change, which limits the footprint of silicon Mach-Zehnder interferometer modulators to millimeters. Other approaches such as silicon microring modulators reduce the operation wavelength range to around 100 pm and are highly sensitive to typical fabrication tolerances and temperature fluctuations. Growing large, high quality wafers of compound semiconductors, and integrating them on silicon or other substrates is expensive, which also restricts their commercialization. In this work, we demonstrate that graphene can be used as the active media for electroabsorption modulators. By tuning the Fermi energy level of the graphene layer, we induced changes in the absorption coefficient of graphene at communication wavelength and achieve a modulation depth above 3 dB. This integrated device also has the potential of working at high speed.

We propose a hybrid optical nanocavity consisting of photonic crystals coupled to a metal surface with a nanoscale air gap between. The hybridization of photonic crystal modes and surface plasmons across the gap forms hybrid cavity modes, which are highly confined in the low-loss air gap region. Deep subwavelength mode volume and high quality factor are demonstrated at telecommunication wavelength, resulting in an extremely large Q/Vmratio of 60 000 λ−3. This new type of high-Q/Vmbroad-band hybrid nanocavity opens up opportunities for various applications in enhanced light−matter interactions.

In this paper, we analyze the biharmonic eigenvalue problem by two nonconforming finite elements, Q1rotand E Q1rot. We obtain full order convergence rate of the eigenvalue approximations for the biharmonic eigenvalue problem based on asymptotic error expansions for these two nonconforming finite elements. Using the technique of eigenvalue error expansion, the technique of integral identities, and the extrapolation method, we can improve the accuracy of the eigenvalue approximations. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008

The SrBi2Ta2O9 (SBT) thin films were prepared by metalorganic decomposition on Pt/TiO2/SiO2/Si substrates with rapid thermal annealing (RTA). The films were annealed at different temperature (T) for different time (t) to investigate the crystal growth of the films. The grain size distribution basically conforms to Gaussian distribution and the rate of nucleation is high with RTA. There are two steps in grain growth. First, grain size is proportion to t1/2 before 10s, then proportion to t1/2. The growth activity energy is about 29kJ/mol under 700°C and 81kJ/mol above 700°C. From the results mentioned above we can draw a conclusion that it is easier to grow larger SBT grains by increasing annealing temperature than by lengthening annealing time in RTA.

The SrBi2Ta2O9 (SBT) thin films were prepared on Pt/TiO2/SiO2/Si substrates by metalorganic decomposition method. The films were annealed layer by layer at 650-800°C for 3minutes in oxygen using rapid thermal annealing. The structure, morphology and electrical properties of as-deposited films were characterized using X-ray diffraction, atomic force microscope, Auger electron spectroscopy and some electrical measurement. The films showed smaller grains, higher density, less interfacial diffusion and smaller remnant polarization than those annealed in conventional tube furnace. The remnant polarization and coercive field at applied voltage of 3 V were 8.7μC/cm2 and 13.4kV/cm, respectively, for the 440nm-thick films annealed at 750°C. The coercive field was much lower than those reported previously. This is advantageous to low voltage applications in nonvolatile memory. The films also exhibited no fatigue after 1010 cycles switching and no loss after 105s retention time.

The unambiguous determination of optical refractive indices of metamaterials is a challenging task for device applications and the study of new optical phenomena. We demonstrate here simple broadband phase measurements of metamaterials using spectrally and spatially resolved interferometry. We study the phase response of a π-shaped metamaterial known to be an analog to electromagnetically induced transparency. The measured broadband interferograms give the phase delay or advance produced by the metamaterial in a single measurement. The presented technique offers an effective way of characterizing optical metamaterials including nonlinear and gain–metamaterial systems.

We report the experimental generation and dynamic trajectory control of plasmonic Airy beams (PABs). The PABs are created by directly coupling free-space Airy beams to surface plasmon polaritons through a grating coupler on a metal surface. We show that the ballistic motion of the PABs can be reconfigured in real time by either a computer addressed spatial light modulator or mechanical means.