Planar optical elements that can manipulate the multidimensional physical parameters of light efficiently and compactly are highly sought after in modern optics and nanophotonics. In recent years, ...the geometric phase, induced by the photonic spin–orbit interaction, has attracted extensive attention for planar optics due to its powerful beam shaping capability. The geometric phase can usually be generated via inhomogeneous anisotropic materials, among which liquid crystals (LCs) have been a focus. Their pronounced optical properties and controllable and stimuli‐responsive self‐assembly behavior introduce new possibilities for LCs beyond traditional panel displays. Recent advances in LC‐mediated geometric phase planar optics are briefly reviewed. First, several recently developed photopatterning techniques are presented, enabling the accurate fabrication of complicated LC microstructures. Subsequently, nematic LC‐based transmissive planar optical elements and chiral LC‐based broadband reflective elements are reviewed systematically. Versatile functionalities are revealed, from conventional beam steering and focusing, to advanced structuring. Combining the geometric phase with structured LC materials offers a satisfactory platform for planar optics with desired functionalities and drastically extends exceptional applications of ordered soft matter. Some prospects on this rapidly advancing field are also provided.
Recent advances in the liquid‐crystal (LC)‐mediated geometric phase are briefly summarized, from nematic‐LC‐mediated transmissive to chiral‐LC‐mediated broadband reflective planar optics. Numerous spin‐controlled functionalities are presented, including not only conventional beam steering and focusing, but also advanced light structuring. A comprehensive understanding of LC‐based geometric phase planar optics and their numerous applications is provided.
The molecular-dynamics simulation of a ternary (solid–liquid–gas) system was performed to investigate the nucleation of nanobubble clusters and the effect of nanobubble flow on nanochannels. Results ...showed that the existence of gaseous nanobubbles can replace the dense and orderly absorbed liquid layer in nonbubble flow. Nanochannels with various surface wettabilities were compared. For the hydrophilic surface, nanobubbles were attracted by the solid surface with a large contact angle, and density fluctuations near the surface decreased. Conversely, the hydrophilic surface exhibited repulsion toward nanobubbles. Simulation results indicated that surface wettability may be enhanced toward its intrinsic property with increased driving velocity. Moreover, introducing the hydrophobic property coupled with high velocity had a dramatic positive effect on drag reduction.
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•Two molecular dynamic simulations of ternary system are carried out to study the nanobubble behavior in a nanochannel.•Nanobubble contact angle was calculated to analyze the formation and stability of surface nanobubbles on wettable surfaces.•The flow behavior was performed to explain the ultra-low friction drag of the nanobubble existence surface.•The hydrophobic property coupled with high velocity had a dramatic positive effect on reducing drag is presented.
Iron-Sulfur (Fe-S) clusters and proteins are essential to many growth and developmental processes. In plants, they exist in the plastids, mitochondria, cytosol, and nucleus. Six types of Fe-S ...clusters are found in the plastid: classic 2Fe-2S, NEET-type 2Fe-2S, Rieske-type 2Fe-2S, 3Fe-4S, 4Fe-4S, and siroheme 4Fe-4S. Classic, NEET-type, and Rieske-type 2Fe-2S clusters have the same 2Fe-2S core; similarly, common and siroheme 4Fe-4S clusters have the same 4Fe-4S core. Plastidial Fe-S clusters are assembled by the sulfur mobilization (SUF) pathway, which contains cysteine desulfurase (EC 2.8.1.7), sulfur transferase (EC 2.8.1.3), Fe-S scaffold complex, and Fe-S carrier proteins. The plastidial cysteine desulfurase-sulfur transferase-Fe-S-scaffold complex system is responsible for
assembly of all plastidial Fe-S clusters. However, different types of Fe-S clusters are transferred to recipient proteins via respective Fe-S carrier proteins. This review focuses on recent discoveries on the molecular functions of different assembly and transfer factors involved in the plastidial SUF pathway. It also discusses potential points for regulation of the SUF pathway, relationships among the plastidial, mitochondrial, and cytosolic Fe-S assembly and transfer pathways, as well as several open questions about the carrier proteins for Rieske-type 2Fe-2S, NEET-type 2Fe-2S, and 3F-4S clusters.
Mesogenic soft materials, having single or multiple mesogen moieties per molecule, commonly exhibit typical self‐organization characteristics, which promotes the formation of elegant helical ...superstructures or supramolecular assemblies in chiral environments. Such helical superstructures play key roles in the propagation of circularly polarized light and display optical properties with prominent handedness, that is, chiro‐optical properties. The leveraging of light to program the chiro‐optical properties of such mesogenic helical soft materials by homogeneously dispersing photosensitive chiral material into an achiral soft system or covalently connecting photochromic moieties to the molecules has attracted considerable attention in terms of materials, properties, and potential applications and has been a thriving topic in both fundamental science and application engineering. State‐of‐the‐art technologies are described in terms of the material design, synthesis, properties, and modulation of photoprogrammable chiro‐optical mesogenic soft helical architectures. Additionally, the scientific issues and technical problems that hinder further development of these materials for use in various fields are outlined and discussed. Such photoprogrammable mesogenic soft helical materials are competitive candidates for use in stimulus‐controllable chiro‐optical devices with high optical efficiency, stable optical properties, and easy miniaturization, facilitating the future integration and systemization of chiro‐optical chips in photonics, photochemistry, biomedical engineering, chemical engineering, and beyond.
Photoprogrammable mesogenic helical soft materials with both photosensitive and mesogenic moieties in molecules possess typical chiro‐optical properties, showing handedness dependency on the transmission, reflection, and absorption of an incident circularly polarized light (photonic bandgap and circular dichroism). This can be modulated readily by light irradiation, thus paving the way toward future chiro‐optical devices and systems.
Composite vortex beams (CVBs) have attracted considerable interest recently due to the unique optical properties and potential applications. However, these beams are mainly generated using spatial ...light modulators, which suffer from large volume, high cost, and limited resolution. Benefiting from the ultrathin nature and unprecedented capability in light manipulation, optical metasurfaces provide a compact platform to perform this task. A metasurface approach to creating these CVBs is proposed and experimentally demonstrated. The design is based on the superposition of multiple circularly polarized vortex beams with different topological charges, which is realized based on a geometric metasurface consisting of metallic nanorods with spatially variant orientations. The effects of the initial phases, amplitude coefficients, incident polarization state, and propagation distance on the generated CVBs, which are in good agreement with the theoretical prediction, are experimentally analyzed. This work has opened a new avenue for engineering CVBs with a minimal footprint, which has promising applications ranging from multiple optical traps to quantum science.
A compact metasurface approach is proposed and experimentally demonstrated to create composite vortex beams. A single geometric metasurface is used to realize the superposition of multiple vortex beams with different circular polarization states. This method provides a compact platform to generate composite vortex beams with engineered singularity distributions, which are fundamentally important for singular optics and quantum science.
Social media‐based online communities are becoming increasingly popular for various social interactions, including those for healthcare and health‐related activities. The benefits from these ...activities, however, are constrained by how a platform is designed, as a platform's design defines what activities can be done and how individuals can engage and interact on the platform. In this study, we focus on weight‐loss communities and social tools that facilitate social communication and establish a variety of relationships between users. In particular, we examine the effectiveness of one‐way and two‐way social relationships on individuals’ weight‐loss management. Drawing from theories of social support, social reciprocity, and social indebtedness, we use two‐way friendship relationships to proxy perceived support and one‐way commenting relationships to proxy received support and conjecture that they work through different pathways. We find, through empirical analyses, that both types of social relationships as well as self‐monitoring are effective in promoting weight loss, but perceived and received support have different impacts. Whereas both perceived and received support are positively related to weight‐loss outcomes, the effect of received support is found to be higher than that of perceived support and the difference is statistically significant. Moreover, we find that received support is positively associated with self‐monitoring behaviors, whereas perceived support is not. These findings provide insights for platform providers to improve the social design aspect of online services and for healthcare practitioners in their efforts to advise individuals on weight self‐management. Our results also can be used to design and implement more effective online interventions.
•The status recycling methods for the precious metal recovery from the waste print circuit board are reviewed.•The effects of environment by the improper recover methods are analyzed.•The bottlenecks ...in precious metals recycling system are proposed.•Addressing future metal recycling challenges and recommendations are presented.
Nowadays, rapid economic growth, continuous technological innovation and the improvement of living standards have result in large amounts of waste electric and electronic equipment (WEEE). Amongst all these WEEE, waste printed circuit boards (WPCBs) are considered as the most valuable components due to precious metals contained. Previous studies found that the presence of precious metals are richer in WPCBs than in typical metal mines, which are driven recycling precious metals from WPCBs to a profitable business without proper pollution controls in developing countries. However, recovering precious metals from WPCBs is a challenge because WPCBs are both valuable and harmful simultaneously, which are caused by their complex materials makeup. Hence, the proper technologies to recycle metals from WPCBs without negative effects to the environment and human health are urgent and essential. In this article, the current metals recycling technologies from WPCBs are reviewed. Then, an integrated technological route, including metals enrichment and precious metals recovery, is proposed. Finally, in order to promote the development of metals (precious metals) recovery from WPCBs, some improvements and recommendations in techniques and the future trend are also put forward.
Photosynthesis, pathogen infection, and plant defense are three important biological processes that have been investigated separately for decades. Photosynthesis generates ATP, NADPH, and ...carbohydrates. These resources are utilized for the synthesis of many important compounds, such as primary metabolites, defense-related hormones abscisic acid, ethylene, jasmonic acid, and salicylic acid, and antimicrobial compounds. In plants and algae, photosynthesis and key steps in the synthesis of defense-related hormones occur in chloroplasts. In addition, chloroplasts are major generators of reactive oxygen species and nitric oxide, and a site for calcium signaling. These signaling molecules are essential to plant defense as well. All plants grown naturally are attacked by pathogens. Bacterial pathogens enter host tissues through natural openings or wounds. Upon invasion, bacterial pathogens utilize a combination of different virulence factors to suppress host defense and promote pathogenicity. On the other hand, plants have developed elaborate defense mechanisms to protect themselves from pathogen infections. This review summarizes recent discoveries on defensive roles of signaling molecules made by plants (primarily in their chloroplasts), counteracting roles of chloroplast-targeted effectors and phytotoxins elicited by bacterial pathogens, and how all these molecules crosstalk and regulate photosynthesis, pathogen infection, and plant defense, using chloroplasts as a major battlefield.
Photosystem II (PSII) is a multi-component pigment-protein complex that is responsible for water splitting, oxygen evolution, and plastoquinone reduction. Components of PSII can be classified into ...core proteins, low-molecular-mass proteins, extrinsic oxygen-evolving complex (OEC) proteins, and light-harvesting complex II proteins. In addition to these PSII subunits, more than 60 auxiliary proteins, enzymes, or components of thylakoid protein trafficking/targeting systems have been discovered to be directly or indirectly involved in de novo assembly and/or the repair and reassembly cycle of PSII. For example, components of thylakoid-protein-targeting complexes and the chloroplast-vesicle-transport system were found to deliver PSII subunits to thylakoid membranes. Various auxiliary proteins, such as PsbP-like (Psb stands for PSII) and light-harvesting complex-like proteins, atypical short-chain dehydrogenase/reductase family proteins, and tetratricopeptide repeat proteins, were discovered to assist the de novo assembly and stability of PSII and the repair and reassembly cycle of PSII. Furthermore, a series of enzymes were discovered to catalyze important enzymatic steps, such as C-terminal processing of the D1 protein, thiol/disulfide-modulation, peptidylprolyl isomerization, phosphorylation and dephosphorylation of PSII core and antenna proteins, and degradation of photodamaged PSII proteins. This review focuses on the current knowledge of the identities and molecular functions of different types of proteins that influence the assembly, stability, and repair of PSII in the higher plant Arabidopsis thaliana.
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