Theoretical research on the transverse spin of structured optical fields inside a waveguide

Structured optical fields inside a waveguide possess the transverse spin, i.e., the spin angular momentum perpendicular to the direction of the waveguide. The physical origin of the transverse spin can be attributed to the presence of an effective rest mass of photons in guided waves, or equivalently, to the existence of a longitudinal field component, such that the transverse and longitudinal fields together form an elliptical polarization plane. In contrary to the traditional viewpoint, the transverse spin of photons in guided waves is also quantized, and its quantization form is related to the ellipticity of the polarization ellipse. The direction of the transverse spin depends on the propagation direction of electromagnetic waves along the waveguide, such a spin-momentum locking may have important applications in spin-dependent unidirectional optical interfaces. By means of a coupling between the transverse spin of guided waves and some physical degrees of freedom, one can develop an optical analogy of spintronics, i.e., spinoptics.

二葡糖基没食子酸的合成及其性能研究

以没食子酸甲酯和五乙酰基葡萄糖为原料,经过乙酰化反应、成盐、酸化等过程合成了美白剂二葡糖基没食子酸,并通过IR,MS,^(1)H NMR和^(13)C NMR确认了最终产物的结构。同时考察了美白剂二葡糖基没食子酸对酪氨酸酶活性的影响、酪氨酸二酚酶的抑制作用机制以及抗氧化能力。研究表明:以L-酪氨酸为底物时,二葡糖基没食子酸对酪氨酸单酚酶的半抑制浓度IC_(50)为1.46 mg/mL,以L-多巴为底物时,二葡糖基没食子酸对酪氨酸二酚酶的半抑制浓度IC_(50)为2.68 mg/mL,而且从Lineweaver-Burk图获得的抑制机理表明二葡糖基没食子酸对酪氨酸二酚酶的抑制作用表现为竞争性抑制,抑制常数K_(m)为2.43 mg/mL。没食子酸相比于同质量浓度下的V_(max)对DPPH自由基的清除效果更好,而二葡糖基没食子酸相比于同质量浓度下的V_(c),其对DPPH自由基仍存在一定的清除作用。

“十四五”时期化解政府隐性债务应关注的几个问题

地方政府隐性债务的大幅扩张引起各级政府主体、各个市场主体的强烈关注,中央政府在化解和防范隐性债务风险方面也不断推出一系列法规政策。基于对地方政府债务扩张的历程和隐性债务大幅扩张逻辑机制的分析,在“十四五”时期化解地方政府隐性债务风险,应重点关注地方政府隐性债务的精确识别、准确评估和风险预警,进一步厘清政府支出责任、企业行为的边界,继续推进融资平台向市场化转型,建立常态化监控机制和问责机制等方面的问题,实现对隐性债务的有效监管和调控。进而充分发挥地方政府显性债务的调控作用,提高公共资源的配置效率,与市场经济发展相适应和相协调,服务于现代经济体系建设和提升国家治理效能。

Reducing surficial and interfacial defects by thiocyanate ionic liquid additive and ammonium formate passivator for efficient and stable perovskite solar cells

Organic–inorganic metal halide perovskites have attained extensive attention owing to their outstanding photovoltaic performances,but the existence of numerous defects in crystalline perovskites is still a serious constraint for the further development of perovskite solar cells(PSCs).In particular,the rapid crystallization guided by anti-solvents leads to plenty of surficial and interfacial defects in perovskite films.Herein,we report the adoption of a pseudo-halide anion based ionic liquid additive,1-butyl-3-methylimidazolium thiocyanate(BMIMSCN)for growing ternary cation(CsFAMA,where FA=formamidinium and MA=methylammonium)perovskites with large-scale crystal grains and strong preferential orientation via the enhanced Ostwald ripening.Meanwhile,a novel halide-free passivator,benzylammonium formate(BAFa),was employed as a buffering layer on the perovskite films to suppress surface-dominated charge recombination.As a result,the cooperative effects of BMIMSCN additive and BAFa passivator lead to significant enhancements on fluorescence lifetime(from 79.41 to 201.01 ns),open-circuit voltage(from 1.13 to 1.19 V),photoelectric conversion efficiency(from 18.90%to 22.33%).Moreover,the BMIMSCN/BAFa-CsFAMA PSCs demonstrated greatly improved stability against moisture and heat.This work suggests a promising strategy to improve the quality of perovskite materials via reducing the surficial and interfacial defects by the synergistic effects of lattice doping and interface engineering.

2D layered black arsenic-phosphorus materials:Synthesis,properties,and device applications

Phosphorene,especially black phosphorus(BP),has attracted considerable attention due to the unique characteristics,such as tunable direct bandgap,high carrier mobility,and strong in-plane anisotropy.Recently,a new modification strategy for black phosphorus has been developed by alloying black phosphorus with the congener element arsenic.The elemental composition tuning of black phosphorus with arsenic can not only maintain its special crystal structure and high anisotropy but also modify its electrical and optical properties for the further applications of multifunctional devices.The achieved two-dimensional(2D)black arsenic-phosphorus materials exhibit outstanding optical,electrical,and photoelectric properties,such as very narrow band gap,anisotropic infrared absorption,and bipolar transfer characteristics,presenting great potential in infrared photodetectors and highperformance field effect transistors(FETs).In this review,we introduce the recent progress made in the synthesis and applications of black arsenic-phosphorus,and provide an outlook and perspectives on the current challenges and future opportunities in this field.We hope that this review can bring new insights and inspirations on the further development of 2D black arsenic-phosphorus based materials and devices.

Identification,expression analysis,and functional characterization of ghrelin and its receptors in spotted sea bass(Lateolabrax maculatus)

Ghrelin(Ghrl),an appetite-inducing peptide hormone secreted by the stomach,is the endogenous ligand for the growth hormone secretagogue receptor(Ghs-r).In this study,we identified the preproghrelin gene and its receptors in spotted sea bass(Lateolabrax maculatus).The ghrl gene consisted of an open reading frame(ORF)of 324 nucleotides encoding 107 amino acids,and the premature protein contained a 20-amino-acid mature peptide.Through a syntenic analysis,we also validated the annotation of growth hormone secretagogue receptor la(ghs-rla)and growth hormone secretagogue receptor la-1ike(ghs-rla-like),which contained seven-transmembrane structures,in spotted sea bass.The ORF of ghs-rla consisted of 1152 bp that encoded a 383-amino-acid protein,and(ghs-rla-like) contained an ORF of 2631 bp and produced a protein with 876 amino acids.A phylogenetic analysis showed that spotted sea bass ghrl and its receptors clustered with those of other fishes and were more distantly related to those of other vertebrates.In situ hybridization revealed that ghrl was highly expressed in the stomach and localized in the mucosa and submucosa.The expression of these genes varied during short-term starvation in a time-dependent manner.In vitro studies showed that after incubation with Ghrl for 3 h enhanced the expression of motilin(mln),gastrin(gas)and cholecystokinin(cck)、but this effect vanished after 6 h of incubation.In summary,Ghrl and its receptors might play important roles in the regulation of food intake in spotted sea bass.

Rapid construction of highly-dispersed cobalt nanoclusters embedded in hollow cubic carbon walls as an effective polysulfide promoter in high-energy lithium-sulfur batteries

The ultrahigh specific energy density and low cost of lithium-sulfur batteries are suitable for the next generation of energy storage.However,the shuttle issue and sluggish conversion kinetics of polysulfides remain unsolved.Confining metal nanoclusters with strong polarity in conductive porous carbon is an effective strategy for tackling such knotty issues.Herein,we design and synthesize hollow cubic carbon embedded with highly dispersed cobalt nanoclusters as an effective sulfur reservoir for lithium sulfur batteries.The large cavity structure and well-dispersed cobalt nanoclusters,with uniform sizes near 11 nm,enable the hosting structure to hold the high sulfur loading,70%capacity retention after 500 cycles at 2 C with a high sulfur loading of 6.5 mg·cm^(−2),effective stress release,accelerated polysulfide conversion,superior rate performance,strong physical confinement and chemical absorption capability.Further density functional theoretical calculations demonstrate that the welldispersed cobalt nanoclusters in the hosting structure play a critical electrocatalytic role in boosting the capability of absorbing and converting polysulfides.