Field distribution of the Z_(2)topological edge state revealed by cathodoluminescence nanoscopy

Photonic topological insulators with robust boundary states can enable great applications for optical communication and quantum emission,such as unidirectional waveguide and single-mode laser.However,because of the diffraction limit of light,the physical insight of topological resonance remains unexplored in detail,like the dark line that exists with the crys-talline symmetry-protected topological edge state.Here,we experimentally observe the dark line of the Z_(2)photonic topo-logical insulator in the visible range by photoluminescence and specify its location by cathodoluminescence characteriza-tion,and elucidate its mechanism with the p-d orbital electromagnetic field distribution which calculated by numerical sim-ulation.Our investigation provides a deeper understanding of Z_(2)topological edge states and may have great signific-ance to the design of future on-chip topological devices.

Synthesis and Evaluation of 2-Amino-4H-Pyran-3-Carbonitrile Derivatives as Antitubercular Agents

A series of 2-amino-4H-pyran-3-carbonitrile derivatives were designed and synthesized. Their antitubercular activities were evaluated against autoluminescent M. tuberculosis H37Ra and standard strain M. tuberculosis H37Rv. No obvious antitubercular activities could be observed (MIC > 10 ug/mL). The results are in sharp contrast with the previously reported data.

Perspective:Acoustic Metamaterials in Future Engineering

Acoustic metamaterials(AMMs)are a type of artificial materials that make use of appropriate structural designs and exhibit exotic properties not found in natural materials,such as negative effective material parameters(e.g.,bulk modulus,mass density,and refractive index).These interesting properties offer novel means for sound manipulation and thus have drawn a great deal of attention.Over the past two decades,tremendous progress has been made in the fundamental research of AMMs,which has not only promoted the development of modern acoustics but also shown the potential of AMMs for engineering applications.Here,we review recent developments in AMMs with a focus on their future engineering,especially in the most promising fields of sound absorption/isolation,acoustic imaging,cloaking,and so on,furthermore,we outline the opportunities and challenges they are encountering.

Why Can China Realize the Continental“Shale Oil Revolution”?

0 INTRODUCTION Continental shale oil is a strategic alternative resource to ensure the safety of national oil supply and improve the level of industrial innovation.China is a large country of continental oil resources,accounting for 90%of the total onshore oil resources;and China is also a major producer of continental oil,accounting for about 93%of the total oil production(Yang et al.,2019;Jia et al.,2018).

Topological photonic crystals:a review

The field of topological photonic crystals has attracted growing interest since the inception of optical analog of quantum Hall effect proposed in 2008.Photonic band structures embraced topological phases of matter,have spawned a novel platform for studying topological phase transitions and designing topological optical devices.Here,we present a brief review of topological photonic crystals based on different material platforms,including all-dielectric systems,metallic materials,optical resonators,coupled waveguide systems,and other platforms.Furthermore,this review summarizes recent progress on topological photonic crystals,such as higherorder topological photonic crystals,non-Hermitian photonic crystals,and nonlinear photonic crystals.These studies indicate that topological photonic crystals as versatile platforms have enormous potential applications in maneuvering the flow of light.

STUDY ON TYPHOON DISASTER LOSS AND RISK PREDICTION AND BENEFIT ASSESSMENT OF DISASTER PREVENTION AND MITIGATION

Based on the meteorological monitoring data of Typhoon Nesat and Haitang in Fujian Province in 2017, the data of the typhoon disaster situation and third-party evaluation of typhoon disaster prevention and mitigation benefit were investigated. By using the mean value anomaly estimation method in the similarity analysis method, it is estimated that typhoon Nesat and Haitang will cause direct economic losses of 0.8 ～ 1.8 billion yuan, and the typhoon disaster risk index evaluation model is used. The disaster risk pre-assessment of Typhoon Nesat and Haitang is carried out. The results of the study and analysis show that the pre-assessment results of Typhoon Nesat and Haitang are basically consistent with the actual disaster situation. The disaster loss was reduced to the minimum. According to the third party evaluation and investigation, it was concluded that the contribution rate of reducing economic benefits was 75% in Fujian Province for preventing and landing double typhoons Nesat and Haitang. Mainly reflected in the ship return to the port to avoid the wind, geological hazards prone to the site construction and cage culture danger removal reinforcement and other links; The contribution rate of reducing casualties is 86, mainly reflected in fishermen disembarkation and personnel transfer to safety emergency shelter and other links. The benefit of this double typhoon disaster prevention and mitigation in Fujian Province is about 0.6 billion yuan to reduce the direct economic loss. According to the investigation, the overall satisfaction of the double typhoon meteorological service is 91.0 points. Typhoon early warning information service convenience satisfaction is 91.4 points, early warning information accuracy satisfaction is 87.2 points, government departments strong anti-Taiwan disaster reduction organization, linkage departments participate in disaster prevention and mitigation high. However, there is a gap between public awareness and participation in typhoon disasters.

Arabidopsis immune-associated nucleotide-binding genes repress heat tolerance at the reproductive stage by inhibiting the unfolded protein response and promoting cell death

Plants are vulnerable to heat stress,especially during reproductive development.The heat shock response(HSR)in the cytosol and nucleus,as well as the unfolded protein response(UPR)in the endoplasmic reticulum(ER),are two mechanisms that enable plants to survive heat stress.Excessive heat or ER stresses lead to cell death when the UPR cannot repair stress damage,but the means by which cell survival or death is determined remains unclear.In this study,we used a genome-wide association study(GWAS)to identify that a cluster of five Immune-associated nucleotide-binding protein(IAN)genes(IAN2 to IAN6)is responsible for variation in heat tolerance at the reproductive stage in Arabidopsis thaliana.These IAN genes have both unique and overlapping functions in the negative regulation of heat tolerance,and their loss of function singly or in combination confers increased heat tolerance,measured by a lower number of barren siliques and a higher seedling survival rate under heat.The loss of rice IAN1 gene function also leads to enhanced heat tolerance,suggesting a conserved function of plant IANs.Transcriptome analysis revealed enhanced expression of HSR and UPR genes,as well as reduced cell death,under heat and ER stress in the mutant of IAN6,a major effect member in Arabidopsis.Furthermore,the IAN proteins were found to promote cell death induced by heat stress,ER stress,and cell death-inducing molecules.Thus,the Arabidopsis IAN genes repress heat tolerance,probably through the HSR and UPR and by enhancing the cell death pathway.The IAN2 to IAN6 proteins are partially localized to the ER,suggesting a direct role in the UPR and UPR-mediated cell death.In addition,a natural IAN6 variant from more heat-tolerant Arabidopsis accessions confers greater heat tolerance and induces less cell death compared with the natural variant from less heat-tolerant accessions.The heat-tolerant IAN6 variant is associated with a higher maximum temperature of the warmest month at its collection sites compared with the heat-sensitive variant.Taken together,these results reveal an important role of Arabidopsis IAN2 to IAN6 genes in the regulation of the HSR,UPR,and cell death,and suggest that their natural variations have adaptive functions in heat tolerance.

Using coupling slabs to tailor surface-acoustic-wave band structures in phononic crystals consisting of pillars attached to elastic substrates

The propagation of surface acoustic waves(SAWs) in two-dimensional phononic crystals(PnCs) with and without coupling-enhancement slabs was theoretically investigated using a three-dimensional finite element method.Different piezoelectric substrates,for example,lithium niobate(LiNbO_3),gallium nitride(GaN),and aluminium nitride(A1N),were taken into account.Compared to the PnCs without coupling-enhancement slabs,the coupling between each pillar and its nearest neighbor was largely enhanced in the presence of slabs.The bandwidth of the first directional band gap increased markedly compared with its initial value for the PnCs without a slab(within square symmetry).In addition,with increasing thicknesses of the slabs bonded between neighboring pillars,the first directional band-gap and second directional band gap of the PnCs tend to merge.Therefore,the structure with coupling-enhancement slabs can be used as an excellent electrical band elimination filter for most electro-SAW devices,offering a new strategy to realize chip-scale applications in electroacoustic signal processing,optoacoustic modulation,and even SAW microfluidic devices.

Metalens in harmony with refractive optics

Optical dispersion is an inherent property of all materials in nature. Due to the dispersion of the optical material and the phase accumulation of the light field at different wavelengths, chromatic aberration is inevitable in commercial optical lens. When taking pictures by lenses with severe chromatic aberration, the images will look blurred or noticeably colored edges (red, green, blue) around the objects, especially in high-contrast situations. Thus, achromatism, correction of the chromatic aberration, is extremely important in broadband optical applications. There are mainly two approaches in the correction of the chromatic aberration in existing optical systems: combining the refractive lenses with different dispersions or introducing the diffractive optical elements. However, it is still a technical challenge to achieve that goal in the entire visible light band.