Actuators that can convert environmental stimuli into mechanical work are widely used in intelligent systems, robots, and micromechanics. To produce robust and sensitive actuators of different ...scales, efforts are devoted to developing effective actuating schemes and functional materials for actuator design. Carbon‐based nanomaterials have emerged as preferred candidates for different actuating systems because of their low cost, ease of processing, mechanical strength, and excellent physical/chemical properties. Especially, due to their excellent photothermal activity, which includes both optical absorption and thermal conductivities, carbon‐based materials have shown great potential for use in photothermal actuators. Herein, the recent advances in photothermal actuators based on various carbon allotropes, including graphite, carbon nanotubes, amorphous carbon, graphene and its derivatives, are reviewed. Different photothermal actuating schemes, including photothermal effect–induced expansion, desorption, phase change, surface tension gradient creation, and actuation under magnetic levitation, are summarized, and the light‐to‐heat and heat‐to‐work conversion mechanisms are discussed. Carbon‐based photothermal actuators that feature high light‐to‐work conversion efficiency, mechanical robustness, and noncontact manipulation hold great promise for future autonomous systems.
This review highlights the recent advances in carbon‐based photothermal actuators. Physical properties and light‐to‐heat conversion mechanisms of various carbon‐based functional materials are summarized. Photothermal actuating schemes such as photothermal expansion, desorption, phase change, surface tension effect, and magnetic susceptibility are reviewed. The current challenges and future perspectives of this field are also discussed.
The challenge to retrieve canopy height from large-footprint satellite lidar waveforms over mountainous areas is formidable given the complex interaction of terrain and vegetation. This study ...explores the potential of GLAS (Geoscience Laser Altimeter System) for retrieving maximum canopy height over mountainous areas in the Pacific Coast region, including two conifers sites of tall and closed canopy and one broadleaf woodland site of shorter and sparse canopy. Both direct methods and statistical models are developed and tested using spatially extensive coincident airborne lidar data. The major findings include: 1) the direct methods tend to overestimate the canopy height and are complicated by the identification of waveform signal start and terrain ground elevation, 2) the exploratory data analysis indicates that the edge-extent linear regression models have better generalizability than the edge-extent nonlinear models at the inter-site level, 3) the inter-site level test with mixed-effects models reveals that the edge-extent linear models have statistically-justified generalizability between the two conifer sites but not between the conifer and woodland sites, 4) the intra-site level test indicates that the edge-extent linear models have statistically-justified generalizability across different vegetation community types within any given site; this, combined with 3), unveils that the statistical modeling of maximum canopy height over large areas with edge-extent linear models only need to consider broad vegetation differences (such as woodlands versus conifer forests instead of different vegetation communities within woodlands or conifer forests), and 5) the simulations indicate that the errors and uncertainty in canopy height estimation can be significantly reduced by decreasing the footprint size. It is recommended that the footprint size of the next-generation satellite lidar systems be at least 10
m or so if we want to achieve meter-level accuracy of maximum canopy height estimation using direct and statistical methods.
Recently, perovskite solar cells (PSCs) have attracted much attention owing to their high power conversion efficiency (25.2%) and low fabrication cost. However, the short lifetime under operation is ...the major obstacle for their commercialization. With efforts from the entire PSC research community, significant advances have been witnessed to improve the device operational stability, and a timely summary on the progress is urgently needed. In this review, we first clarify the definition of operational stability and its significance in the context of practical use. By analyzing the mechanisms in established approaches for operational stability improvement, we summarize several effective strategies to extend device lifetime in a layer-by-layer sequence across the entire PSC. These mechanisms are discussed in the contexts of chemical reactions, photo-physical management, technological modification,
etc.
, which may inspire future R&D for stable PSCs. Finally, emerging operational stability standards with respect to testing and reporting device operational stability are summarized and discussed, which may help reliable device stability data circulate in the research community. The main target of this review is gaining insight into the operational stability of PSCs, as well as providing useful guidance to further improve their operational lifetime by rational materials processing and device fabrication, which would finally promote the commercialization of perovskite solar cells.
This review gives insight into the operational stability of perovskite solar cells and provides possible research direction for further improvement.
Incorporating a dipole interlayer has been one of the most crucial interfacial engineering strategies in organic and perovskite solar cells. An interfacial dipole brings steep shifts in electronic ...band structure across interfaces and thus effectively tunes charge carrier transport. However, the origin of the interfacial dipole and its effects on device performance are not entirely clear; they are even controversial in some cases. We devote this Perspective to identifying the electric dipole of various interlayers and correlating the interfacial dipole with device performance on the basis of classical semiconductor device theory. It is important to further consider the chemical nature of interlayers beyond the simplified model of an interfacial dipole to develop a full understanding of interfacial structure, energy bands, and device operation mechanism. Researchers are encouraged to integrate in situ and in operando characterizations with numerical simulations in future studies.
Dye and nitro-compound pollution has become a significant issue worldwide. The adsorption and degradation of dyes and nitro-compounds have recently become important areas of study. Different methods, ...such as precipitation, flocculation, ultra-filtration, ion exchange, coagulation, and electro-catalytic degradation have been adopted for the adsorption and degradation of these organic pollutants. Apart from these methods, adsorption, photocatalytic degradation, and chemical degradation are considered the most economical and efficient to control water pollution from dyes and nitro-compounds. In this review, different kinds of dyes and nitro-compounds, and their adverse effects on aquatic organisms and human beings, were summarized in depth. This review article covers the comprehensive analysis of the adsorption of dyes over different materials (porous polymer, carbon-based materials, clay-based materials, layer double hydroxides, metal-organic frameworks, and biosorbents). The mechanism and kinetics of dye adsorption were the central parts of this study. The structures of all the materials mentioned above were discussed, along with their main functional groups responsible for dye adsorption. Removal and degradation methods, such as adsorption, photocatalytic degradation, and chemical degradation of dyes and nitro-compounds were also the main aim of this review article, as well as the materials used for such degradation. The mechanisms of photocatalytic and chemical degradation were also explained comprehensively. Different factors responsible for adsorption, photocatalytic degradation, and chemical degradation were also highlighted. Advantages and disadvantages, as well as economic cost, were also discussed briefly. This review will be beneficial for the reader as it covers all aspects of dye adsorption and the degradation of dyes and nitro-compounds. Future aspects and shortcomings were also part of this review article. There are several review articles on all these topics, but such a comprehensive study has not been performed so far in the literature.
The recognition of microbial nucleic acids is a major mechanism by which the immune system detects pathogens. Cyclic GMP-AMP (cGAMP) synthase (cGAS) is a cytosolic DNA sensor that activates innate ...immune responses through production of the second messenger cGAMP, which activates the adaptor STING. The cGAS-STING pathway not only mediates protective immune defense against infection by a large variety of DNA-containing pathogens but also detects tumor-derived DNA and generates intrinsic antitumor immunity. However, aberrant activation of the cGAS pathway by self DNA can also lead to autoimmune and inflammatory disease. Thus, the cGAS pathway must be properly regulated. Here we review the recent advances in understanding of the cGAS-STING pathway, focusing on the regulatory mechanisms and roles of this pathway in heath and disease.
Wide bandgap oxide semiconductors constitute a unique class of materials that combine properties of electrical conductivity and optical transparency. They are being widely used as key materials in ...optoelectronic device applications, including flat‐panel displays, solar cells, OLED, and emerging flexible and transparent electronics. In this article, an up‐to‐date review on both the fundamental understanding of materials physics of oxide semiconductors, and recent research progress on design of new materials and high‐performing thin film transistor (TFT) devices in the context of fundamental understanding is presented. In particular, an in depth overview is first provided on current understanding of the electronic structures, defect and doping chemistry, optical and transport properties of oxide semiconductors, which provide essential guiding principles for new material design and device optimization. With these principles, recent advances in design of p‐type oxide semiconductors, new approaches for achieving cost‐effective transparent (flexible) electrodes, and the creation of high mobility 2D electron gas (2DEG) at oxide surfaces and interfaces with a wealth of fascinating physical properties of great potential for novel device design are then reviewed. Finally, recent progress and perspective of oxide TFT based on new oxide semiconductors, 2DEG, and low‐temperature solution processed oxide semiconductor for flexible electronics will be reviewed.
Wide‐bandgap oxide semiconductors uniquely combine electrical conductivity and optical transparency and are widely used in optoelectronic devices. The materials physics of wide‐bandgap oxide semiconductors, the recent progress in the design of new materials and novel thin‐film transistor (TFT) devices, and current challenges and perspectives are reviewed.
Burgers-type equations are used to describe certain phenomena in gas dynamics, traffic flow, plasma astrophysics and ocean dynamics. In this paper, a (2
+
1)-dimensional generalized Burgers system ...with the variable coefficients in a fluid is investigated. We obtain the Painlevé-integrable constraints of the system with respect to the variable coefficients. Based on the truncated Painlevé expansions, an auto-Bäcklund transformation is constructed, along with some soliton solutions. Via a truncated Painlevé expansions, certain multiple kink solutions are derived. Via a complex-conjugate transformation, some breather solutions, half-periodic kink solutions and hybrid solutions composed of the breathers and kink waves are seen.
Summary
Using genetic resistance against bacterial blight (BB) caused by Xanthomonas oryzae pathovar oryzae (Xoo) is a major objective in rice breeding programmes. Prime editing (PE) has the ...potential to create novel germplasm against Xoo. Here, we use an improved prime‐editing system to implement two new strategies for BB resistance. Knock‐in of TAL effector binding elements (EBE) derived from the BB susceptible gene SWEET14 into the promoter of a dysfunctional executor R gene xa23 reaches 47.2% with desired edits including biallelic editing at 18% in T0 generation that enables an inducible TALE‐dependent BB resistance. Editing the transcription factor TFIIA gene TFIIAγ5 required for TAL effector‐dependent BB susceptibility recapitulates the resistance of xa5 at an editing efficiency of 88.5% with biallelic editing rate of 30% in T0 generation. The engineered loci provided resistance against multiple Xoo strains in T1 generation. Whole‐genome sequencing detected no OsMLH1dn‐associated random mutations and no off‐target editing demonstrating high specificity of this PE system. This is the first‐ever report to use PE system to engineer resistance against biotic stress and to demonstrate knock‐in of 30‐nucleotides cis‐regulatory element at high efficiency. The new strategies hold promises to fend rice off the evolving Xoo strains and protect it from epidemics.
