8 research outputs found
Transient LossâInduced NonâHermitian Degeneracies for Ultrafast Terahertz Metadevices
Abstract NonâHermitian degeneracies, also known as exceptional points (EPs), have attracted considerable attention due to their unique physical properties. In particular, metasurfaces related to EPs can open the way to unprecedented devices with functionalities such as unidirectional transmission and ultraâsensitive sensing. Herein, an active nonâHermitian metasurface with a lossâinduced parityâtime symmetry phase transition for ultrafast terahertz metadevices is demonstrated. Specifically, the eigenvalues of the nonâHermitian transmission matrix undergo a phase transition under optical excitation and are degenerate at EPs in parameter space, which is accompanied by the collapse of chiral transmission. Ultrafast EP modulation on a picosecond time scale can be realized through variations in the transient loss at a nonâHermitian metasurface pumped by pulsed excitation. Furthermore, by exploiting the physical characteristics of chiral transmission EPs, a switchable quarterâwave plate based on the photoactive metasurface is designed and experimentally verified and realized the corresponding function of polarization manipulation. This work opens promising possibilities for designing functional terahertz metadevices and fuses EP physics with active metasurfaces
Copper/Iron-Catalyzed Aerobic Oxyphosphorylation of Terminal Alkynes Leading to βâKetophosphonates
A copper/iron-catalyzed
oxyphosphorylation of alkynes with H-phosphonates
through a radical process was developed. The present protocol provides
an attractive approach to β-ketophosphonates in moderate to
good yields, with the advantages of readily available substrate, high
functional group tolerance and operation simplicity
Recent Advances in LDH/g-C<sub>3</sub>N<sub>4</sub> Heterojunction Photocatalysts for Organic Pollutant Removal
Environmental pollution has been decreased by using photocatalytic technology in conjunction with solar energy. An efficient method to obtain highly efficient photocatalysts is to build heterojunction photocatalysts by combining graphitic carbon nitride (g-C3N4) with layered double hydroxides (LDHs). In this review, recent developments in LDH/g-C3N4 heterojunctions and their applications for organic pollutant removal are systematically exhibited. The advantages of LDH/g-C3N4 heterojunction are first summarized to provide some overall understanding of them. Then, a variety of approaches to successfully assembling LDH and g-C3N4 are simply illustrated. Last but not least, certain unmet research needs for the LDH/g-C3N4 heterojunction are suggested. This review can provide some new insights for the development of high-performance LDH/g-C3N4 heterojunction photocatalysts. It is indisputable that the LDH/g-C3N4 heterojunctions can serve as high-performance photocatalysts to make new progress in organic pollutant removal
Typical cathode materials for lithiumâion and sodiumâion batteries: From structural design to performance optimization
Abstract Rechargeable lithiumâion and sodiumâion batteries (SIB) have dominated the energy storage fields such as electric vehicles and portable electronics due to their high energy density, long cycle life, and environmental friendliness. However, the critical bottleneck hindering the further improvement of their electrochemical performance is the unsatisfactory cathode materials, typically exhibiting inherent drawbacks such as low reversible capacity, initial capacity loss, fast capacity decay, and poor rate performance. These issues are mainly attributed to changes in the internal structure of cathode materials, such as irreversible transformation of particle morphology, evolution of crystal structure, and undesired physicochemical interfacial reactions during the electrochemical process. To address above obstacles, abundant research efforts have been devoted to stabilizing the structural evolution of cathode materials and enhancing their electrochemical performance. Herein, we reviewed the research progress on the cathode materials for lithiumâion and SIBs. The typical cathodes and their structural characteristics, electrochemical behaviors, reaction mechanisms, and strategies for electrochemical performance optimization were summarized. This review aims to promote the understanding of the structureâperformance relationship in the cathode materials and provide some guidance for the design of advanced cathode materials for lithiumâion and SIBs from the perspective of crystal structure
Performance of the first beam on Shenguang III technical Integration Line
Technical Integration Line (TIL), which is being
constructed at CAEP, is the prototype of Shenguang III fusion laser
facility. Experimental results during the first integrated tests on the
first line demonstrate that the laser system architecture from master
oscillator through the laser amplifiers can meet the requirement of TIL
engineering design. In this paper, brief introduction of TIL and main
experiment results are presented