hydrocarbon belts due to their potential applications in carbon nanotechnology.By contrast,heteroatomembedded zigzag hydrocarbon belts as advanced design strategies with fascinating structures and desirable,unique pro...hydrocarbon belts due to their potential applications in carbon nanotechnology.By contrast,heteroatomembedded zigzag hydrocarbon belts as advanced design strategies with fascinating structures and desirable,unique properties have remained largely unexplored,and inherently chiral ones are unknown.Herein,we report the synthesis of a diversity of symmetric and highly enantiopure inherently chiral O-and N-doped zigzag-type hydrocarbon belts starting from strainless macrocycles based on fjord-stitching strategy.The readily available pertriflated resorcin[6]arene underwent partial hydrolyses and intramolecular S_(N)Ar reactions to form a calix[3](9H-xanthene)derivative and a prochiral half-belt selectively.Straightforward transformations of calix[3](9H-xanthene)into C_(3v)-symmetric molecular belts were achieved by closing the rest of the fjords with triple intramolecular S_(N)Ar reactions and Yamamoto homo coupling reactions,as well as palladiumcatalyzed intermolecular acridination reactions with primary amines.The prochiral half-belt underwent enantioselective desymmetrizative mono-acridination to afford an inherently chiral N,O_(4)-bridged pseudo-belt with an enantiomeric excess(ee)value of>99%under the catalysis of Pd(OAc)_(2)and(R)-Antphos.Ring closure reactions of the pseudo-belt produced diverse heteroatom-inlayed zigzag-type hydrocarbon belts of inherent chirality.Further,we showed the unique cavity structures of the belts and demonstrated interesting chiroptic properties of the inherently enantiopure chiral belts.This research opens the door for the exploration of novel and sophisticated symmetric and inherently chiral molecular nanobelt structures with outstanding physical and chemical properties,as well as potential applications.展开更多
We present the interesting result that under sinusoidal field detuning setting along the propagation direction of 1D atomic lattices, the probe susceptibility response of the lattices, regardless of atomic configurati...We present the interesting result that under sinusoidal field detuning setting along the propagation direction of 1D atomic lattices, the probe susceptibility response of the lattices, regardless of atomic configuration, uniformly demonstrates pseudo-PT-antisymmetry, which by our definition corresponds to n(z)=-n*(-z), the complex refractive index antisymmetry along propagation axis, and when being cast back to quantum mechanical side, corresponds to V (x, t)=-V*(x,-t), the conjugate time-reversal antisymmetry of complex potential. We define this as the pseudoPT-antisymmetry, and prove the reason for this phenomenon to be the quantum-mechanical nature described by master equation under weak field approximation for any configuration of 1D atomic lattices. This work will help to deepen the understanding of origin of optical response features of atomic lattices, and will certainly open up the gate to a more rigorous, durable and flexible method of atomic optical lattice design.展开更多
The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous ma...The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous material in uniform and zigzag manner on the rib surface of the flow field. The study focuses on enhancing the performance of PEMFC by reducing liquid flooding in the interface between the rib and Gas Diffusion Layer (GDL). A single PEMFC having an active area of 25 cm2, with three flow channel designs (conventional serpentine, pin type flow channel with 2 mm cubical porous inserts in zigzag and uniform pattern) are modeled for the numerical analysis. The effect of porosity of the carbon inserts on the cell performance is studied by varying its value from 0.6 to 0.9. The results show that the performance of the flow channel with zigzag and uniformly positioned porous inserts is more than the conventional serpentine flow channel by 20.36% and 16.87% respectively. The reason for this increase is the removal of the accumulated water from the rib surface due to the capillary action of the porous carbon inserts. This helps in eliminating the stagnant water regions under the rib and thereby helps in reducing liquid flooding.展开更多
The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed. It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses w...The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed. It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses with the number of bounces of light within the slab, which can be well explained by the trace of the zigzag propagation. In addition, we conclude that the beamlet with a larger number of bounces experiences weaker thermal lensing but more serious wavefront deformation due to the large side lobe portion in the curve of optical path difference.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,grant nos.22050005,21920102001,22171160,and 22371161)Tsinghua University Dushi Program,and China National Postdoctoral Program for Innovative Talents(grant no.BX20220184).
文摘hydrocarbon belts due to their potential applications in carbon nanotechnology.By contrast,heteroatomembedded zigzag hydrocarbon belts as advanced design strategies with fascinating structures and desirable,unique properties have remained largely unexplored,and inherently chiral ones are unknown.Herein,we report the synthesis of a diversity of symmetric and highly enantiopure inherently chiral O-and N-doped zigzag-type hydrocarbon belts starting from strainless macrocycles based on fjord-stitching strategy.The readily available pertriflated resorcin[6]arene underwent partial hydrolyses and intramolecular S_(N)Ar reactions to form a calix[3](9H-xanthene)derivative and a prochiral half-belt selectively.Straightforward transformations of calix[3](9H-xanthene)into C_(3v)-symmetric molecular belts were achieved by closing the rest of the fjords with triple intramolecular S_(N)Ar reactions and Yamamoto homo coupling reactions,as well as palladiumcatalyzed intermolecular acridination reactions with primary amines.The prochiral half-belt underwent enantioselective desymmetrizative mono-acridination to afford an inherently chiral N,O_(4)-bridged pseudo-belt with an enantiomeric excess(ee)value of>99%under the catalysis of Pd(OAc)_(2)and(R)-Antphos.Ring closure reactions of the pseudo-belt produced diverse heteroatom-inlayed zigzag-type hydrocarbon belts of inherent chirality.Further,we showed the unique cavity structures of the belts and demonstrated interesting chiroptic properties of the inherently enantiopure chiral belts.This research opens the door for the exploration of novel and sophisticated symmetric and inherently chiral molecular nanobelt structures with outstanding physical and chemical properties,as well as potential applications.
基金Support from National Basic Research Program of China under Grant No.2014CB921403National Natural Science Foundation of China under Grant Nos.11534002,U1730449 and U1530401
文摘We present the interesting result that under sinusoidal field detuning setting along the propagation direction of 1D atomic lattices, the probe susceptibility response of the lattices, regardless of atomic configuration, uniformly demonstrates pseudo-PT-antisymmetry, which by our definition corresponds to n(z)=-n*(-z), the complex refractive index antisymmetry along propagation axis, and when being cast back to quantum mechanical side, corresponds to V (x, t)=-V*(x,-t), the conjugate time-reversal antisymmetry of complex potential. We define this as the pseudoPT-antisymmetry, and prove the reason for this phenomenon to be the quantum-mechanical nature described by master equation under weak field approximation for any configuration of 1D atomic lattices. This work will help to deepen the understanding of origin of optical response features of atomic lattices, and will certainly open up the gate to a more rigorous, durable and flexible method of atomic optical lattice design.
文摘The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous material in uniform and zigzag manner on the rib surface of the flow field. The study focuses on enhancing the performance of PEMFC by reducing liquid flooding in the interface between the rib and Gas Diffusion Layer (GDL). A single PEMFC having an active area of 25 cm2, with three flow channel designs (conventional serpentine, pin type flow channel with 2 mm cubical porous inserts in zigzag and uniform pattern) are modeled for the numerical analysis. The effect of porosity of the carbon inserts on the cell performance is studied by varying its value from 0.6 to 0.9. The results show that the performance of the flow channel with zigzag and uniformly positioned porous inserts is more than the conventional serpentine flow channel by 20.36% and 16.87% respectively. The reason for this increase is the removal of the accumulated water from the rib surface due to the capillary action of the porous carbon inserts. This helps in eliminating the stagnant water regions under the rib and thereby helps in reducing liquid flooding.
基金supported by the National Natural Science Foundation of China(Grant Nos.50721004 and 60978032)
文摘The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed. It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses with the number of bounces of light within the slab, which can be well explained by the trace of the zigzag propagation. In addition, we conclude that the beamlet with a larger number of bounces experiences weaker thermal lensing but more serious wavefront deformation due to the large side lobe portion in the curve of optical path difference.
