Identifying high-order plasmon modes in silver nanoparticle-over-mirror configuration.

Metallic nanoparticle-over-mirror (NPOM) represents as a versatile plasmonic configuration for surface enhanced spectroscopy, sensing and light-emitting metasurfaces. However, experimentally identifying the high-order localized surface plasmon modes in NPOM, especially for the best plasmonic material silver, is often hindered by the small scattering cross-section of high-order plasmon modes and the poor reproducibility of the spectra across different NPOMs, resulted from the polyhedral morphology of the colloidal nanoparticles or the rough surface of deposited polycrystalline metals. In this study, we identify the high-order localized surface plasmon modes in silver NPOM by using differential reflection spectroscopy. We achieved reproducible single-particle absorption spectra by constructing uniform NPOM consisting of silver nanospheres, single-crystallized silver microplates, and a self-assembled monolayer of 1,10-decanedithiol. For comparison, silver NPOM created from typical polycrystalline films exhibits significant spectral fluctuations, even when employing template stripping methods to minimize the film roughness. Identifying high-order plasmon modes in the NPOM configuration offers a pathway to construct high-quality plasmonic substrates for applications such as colloidal metasurface, surface-enhanced Raman spectroscopy, fluorescence, or infrared absorption.

Output energy enhancement in a mode-locked Er-doped fiber laser using CVD-Bi2Se3 as a saturable absorber.

In this study, the output energy in topological insulators (TIs)-based Erbium-doped fiber laser (EDFL) was improved using two strategies: bidirectional pumped laser cavity and saturable absorber (SA) with high damage threshold and large modulation depth. Using the chemical vapor deposition (CVD) method, Bismuth Selenide (Bi2Se3) film was synthesized and improved to a SA. Employing this CVD-Bi2Se3 SA in an EDFL, bright and bright-dark soliton operations were achieved. The average output power/pulse energy was 82.6 mW/48.3 nJ and 81.2 mW/47.5 nJ, respectively. The results demonstrate that CVD-Bi2Se3 can act as an excellent performance material to improve output power performance in TISA-based EDFL.

Graphene-Ag nanoparticles-cicada wings hybrid system for obvious SERS performance and DNA molecular detection.

In recent years, biomaterials have increasingly attracted attention on surface-enhanced Raman spectroscopy (SERS) due to their well Raman performance while metal particles are combined with biological substrates. Therefore, we propose an environmentally friendly substrate based on silver-plated cicada wings with seamless graphene layer (Gr-AgNPs-C.w.), which can be prepared with a simple and inexpensive method. Compared with AgNPs-C.w., Gr-AgNPs-C.w. hybrids show better SERS performance with high sensitivity, good uniformity and good stability with R6G detection. The minimum detected concentration can reach 10-15 M, and the value of R2 can reach 0.996, respectively. Theoretical simulation demonstrates the situation of electromagnetic field through COMSOL software. In addition, due to the affinity of graphene for biomolecules, we can successfully detect the DNA biomolecules through a simple process. Therefore, this cheap and efficient natural SERS substrate has great potential for a considerable number of biochemical SERS applications and can broaden the way in which multiple SERS platforms derived from other natural materials are prepared.

Noise-like mode-locked Yb-doped fiber laser in a linear cavity based on SnS2 nanosheets as a saturable absorber.

In this study, a high-energy noise-like mode-locked Yb-doped fiber laser in a linear cavity was achieved with SnS2-polyvinyl alcohol film as the saturable absorber. In addition, the nonlinear saturable absorption characteristics of the SnS2 were investigated experimentally. The saturation intensity and modulation depth were about 6.01 MW/cm2 and 8.68%, respectively. Under pump power of 422 mW, stable noise-like mode-locked operation with a maximum output power and largest single pulse energy of 9.50 mW and 18.1 nJ, respectively, was obtained. To the best of our knowledge, this study is the first to observe and experimentally investigate noise-like operation in a linear laser cavity. Our study may provide some valuable design guidelines for noise-like operation and create new directions for advanced photonic devices based on SnS2.

Generation of high-energy rectangular pulses in a nonlinear polarization rotation mode-locked ring fiber laser.

In this paper, a novel high-energy mode-locked fiber laser based on the nonlinear polarization rotation (NPR) technique is presented to generate 331 nJ rectangular pulses. When pump power was 2659 mW, the maximum output power would be 102.3 mW; the maximum peak power was 41.74 W under the pump power of 1766 mW. In this study, the use of two homemade laser diodes and other common fiber devices was a vital step to achieve the low-cost and high-efficiency NPR mode-locked fiber laser. Based on these results, a novel approach could be developed to realize a high-energy rectangular pulse and promote the practical applications of the NPR mode-locked fiber laser in the field of ultrafast photonics.

Sensitive, reproducible, and stable 3D plasmonic hybrids with bilayer WS2 as nanospacer for SERS analysis.

The highly enhanced local electromagnetic field occurring through nanometer gap between the plamonic nanostructures provides the dominant contribution in surface enhancement Raman scattering (SERS) enhancement. Thence, we designed the remarkable SERS platform (AuNPs/WS2@AuNPs hybrids) by introducing bilayer WS2 film as the precise nanospacer. Bilayer WS2 film can realize the facile and tight combination with AuNPs via the thermal decomposition approach. Dense three-dimension (3D) hot spots provided by this hybrid plasmonic nanostructures are responsible for the extremely satisfying SERS performances. Using rhodamine 6G (R6G) as the probe molecules, the AuNPs/WS2@AuNPs hybrids perform the excellent sensitivity with the minimum detectable concentration as low as 10-11 M. Uniform and reproducible SERS signals illustrate that the synthesized SERS hybrids perform the splendid spot-to-spot reproducibility (RSD~5.4%) and substrate-to-substrate reproducibility (RSD~5.7%). The stability of AuNPs and the protection of WS2 film endow this hybrid plasmonic nanostructures with the brilliant anti-oxidation stability. Moreover, the enhanced electric field distribution simulated with the COMSOL software proves the remarkable SERS performance in theory. Therefore, AuNPs/WS2@AuNPs substrate not only widens the SERS research filed of WS2, but also shows vast potential as excellent SERS sensor for practical applicability.

Discovery of novel salicylaldehyde derivatives incorporating an α-methylene-γ-butyrolactone moiety as fungicidal agents.

BACKGROUND: Plant diseases caused by phytopathogenic fungi and oomycetes pose a serious threat to ensuring crop yield and quality. Finding novel fungicidal candidates based on natural products is one of the critical methods for developing effective and environmentally friendly pesticides. In this study, a series of salicylaldehyde derivatives containing an α-methylene-γ-butyrolactone moiety were designed, synthesized, and their fungicidal activities were evaluated. RESULTS: The bioassay studies indicated that compound C3 displayed an excellent in vitro activity against Rhizoctonia solani with a half-maximal effective concentration (EC50 ) value of 0.65 µg/mL, higher than that of pyraclostrobin (EC50 = 1.44 µg/mL) and comparable to that of carbendazim (EC50 = 0.33 µg/mL). For Valsa mali and Phytophthora capsici, compound C3 also showed good fungicidal activities with EC50 values of 0.91 and 1.33 µg/mL, respectively. In addition, compound C3 exhibited promising protective in vivo activity against R. solani (84.1%) at 100 µg/mL, which was better than that of pyraclostrobin (78.4%). The pot experiment displayed that compound C3 had 74.8% protective efficacy against R. solani at 200 µg/mL, which was comparable to that of validamycin (78.2%). The antifungal mode of action research indicated that compound C3 could change the mycelial morphology and ultrastructure, increase cell membrane permeability, affect respiratory metabolism by binding to complex III, and inhibit the germination and formation of sclerotia, thereby effectively controlling the disease. CONCLUSION: The present study provides support for the application of these salicylaldehyde derivatives as promising potential pesticides with remarkable and broad-spectrum fungicidal activities against phytopathogenic fungi and oomycetes in crop protection. © 2023 Society of Chemical Industry.

In situ electrochemical modification of the Li/Li1.3Al0.3Ti1.7(PO4)3 interface in solid lithium metal batteries via an electrolyte additive.

Solid-state Li batteries employing Li-metal anodes and solid Li/Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolytes have emerged as promising next-generation energy storage devices due to their high energy density and safety. However, their performance is seriously limited by the irreversible reactivity of LATP with the Li-metal anode and the poor solid-solid interfacial contact between them, which result in relatively low ionic conductivity at the interface. The present work addresses these issues by presenting a method for modifying the Li/LATP interface in situ by applying 2-(trimethylsilyl) phenyl trifluoromethanesulfonate (2-(TMS)PTM) as a new type of electrolyte additive between the Li anode and the LATP electrolyte when assembling the battery, and then forming a uniform and thin interfacial layer via redox reactions occurring during the application of multiple charge-discharge cycles to the resulting battery. As a result of the significantly improved chemical compatibility between the Li anode and the LATP electrolyte, an as-assembled battery delivers a high reversible capacity of 165.7 mAh g-1 and an outstanding capacity retention of 86.2% after 300 charge-discharge cycles conducted at a rate of 0.2C and a temperature of 30 °C. Accordingly, this work provides a new strategy for developing advanced solid-state Li metal batteries by tailoring the interface between the Li anode and the solid electrolyte.

Enhanced ionic conductivity and interface compatibility of PVDF-LLZTO composite solid electrolytes by interfacial maleic acid modification.

Improving conductivity and optimizing interface contact are two primary targets to promote the development of solid-state electrolytes. Herein, maleic acid (MA) is introduced into normal PVDF-LLZTO(Li6.75La3Zr1.75Ta0.25O12) based composite polymer-ceramic electrolytes (CPEs). Benefiting the self-polymerization of MA, a core-shell structure is spontaneously formed with LLZTO as core and MA nano-film as shell, the MA shell builds a bridge to link LLZTO and PVDF. In addition, carboxyl groups in MA provide extra channels for Li+ transmission. As a proof, the optimized 25MA-75PVDF-LLZTO CPEs demonstrates an enhanced conductivity as high as 1.15 × 10-3 S cm-1 at 30 °C, an extended electrochemical window up to < 5.0 V, a raised Li+ transfer number of 0.596, and an improved compatibility with Li metal anode. The as-prepared Li‖25MA-75PVDF-LLZTO CPEs‖LiFePO4 full cell delivers an initial specific discharge capacity of 170.5 mAh g-1 at 0.2C, a high rate capability up to 1.0C with 138 mAh g-1 and an excellent long-term cycling stability of over 180cycles without capacity attenuation. The work provides a new strategy to optimize solid state lithium batteries by introducing unsaturated small organic molecules.

A bibliometric analysis of preoperative anxiety research (2001-2021).

Recently, mental health has received increasing attention, particularly preoperative anxiety, which constitutes a bad emotional experience for surgical patients. Many experts have studied preoperative anxiety in terms of its related risk factors, interventions, and postoperative effects; however, there has been no systematic analysis of published articles. This paper presents a bibliometric review of documents related to preoperative anxiety published between 2001 and 2021. A detailed data analysis of 1,596 publications was conducted using CiteSpace and VOSviewer. Since the 20th century, the field of preoperative anxiety has gradually developed; research began around 2000 and has made a huge leap forward since 2016. Developed countries, led by the United States, were the first to conduct research, but preoperative anxiety research in developing countries like Turkey and China has gradually increased and led to an irreplaceable contribution. Intervention has remained the main topic of preoperative anxiety research, and measures have developed from premedication to the provision of education and information. Moreover, the use of advanced equipment such as virtual reality has emerged with great popularity. Based on previous research, the application of virtual reality combined with pediatric patients will become a new research direction.

Genetic Diversity and Population Structure of Hemiculter leucisculus (Basilesky, 1855) in Xinjiang Tarim River.

Hemiculter leucisculus is an invasive fish and widely distributed in the Xinjiang Tarim River. In this study, RAD-seq was used to explore the genetic diversity and population subgroup structure of H. leucisculus in the Tarim River and develop relevant Simple Sequence Repeat (SSR) markers. The study collected 40 samples distributed at four different sites of the Tarim River. A total of 7,291,260 single nucleotide polymorphisms (SNPs) were obtained. The genetic diversity results showed that the population genetic diversity level of H. leucisculus was low. The population pairwise FST values ranged from 0.231 to 0.258, indicating that there was moderate genetic differentiation among these populations. AMOVA showed that the genetic variation within populations accounted for 92.31% of the total variation. The principal component analysis (PCA) and neighbor joining (NJ) tree revealed that the four populations could be separated into two clusters (upper-middle and downstream populations) and the individuals from Taitema Lake (TTMH) showed differences and had a bigger geographic distance than the others. There is the probability that the H. leucisculus from Bosten Lake entered Taitema Lake to breed and then expanded into the Tarim River due to the water diversion projects in location. In addition, 147,705 SSRs loci were detected and 22,651 SSR primer pairs were developed. This study will contribute to providing valuable molecular data for the management of wild populations, marker-assisted selection and resource exploitation of H. leucisculus.

Suppressing the Phase Segregation with Potassium for Highly Efficient and Photostable Inverted Wide-Band Gap Halide Perovskite Solar Cells.

Wide-band gap (WBG) mixed-halide perovskites have drawn much attention because of their excellent optoelectronic properties and the potential to be deployed in tandem solar cells. Nevertheless, the bromine incorporation inevitably leads to photoinduced phase segregation in WBG mixed-halide perovskites. Herein, potassium is used to effectively suppress photoinduced phase segregation, which is visualized with confocal photoluminescence microscopy imaging. Strikingly, the potassium passivation not only inhibits the formation of the narrow-band gap subphase but also enhances the crystallinity of the WBG mixed-halide perovskite. In addition, the potassium-passivated WBG perovskite exhibits lower defect density, longer charge carrier lifetime, and better photostability. As a result, the optimized KI (2 mol %)-passivated WBG perovskite solar cells (PSCs) deliver a champion power conversion efficiency of 18.3% with negligible hysteresis. They maintain 98% of their initial efficiency after 400 h under 100 mW·cm-2 white light illumination in nitrogen.

Global asymptotic stability for the SEIRS models with varying total population size.

In this paper, SEIRS epidemiological model with disease caused death and varying total population size is discussed. Based on the geometric approach developed by Li and Muldowney, a new criterion to determine the global asymptotic stability for nonlinear system is proposed. By applying this new criterion, global asymptotic stability of the endemic equilibrium when it is unique is proved. The above global result shows that the basic reproduction number is a sharp threshold for SEIRS model which removes restrictions of rate of loss of immunity and rate of disease caused death in Li and Muldowney's result.

Permanence for two-species Lotka-Volterra cooperative systems with delays.

In this paper, a two-species Lotka-Volterra cooperative delay system is considered, and the relationships between the delays and the permanence are obtained. Some sufficient conditions for the permanence under the assumption of smallness of the delays are obtained. Two examples are given to illustrate the theorems.

Permanence for two-species lotka-volterra systems with delays.

The permanence of the following Lotka-Volterra system with time delays x '(1) ( t ) = x(1) ( t ) [ r(1) - a(1)x(1) ( t ) + a(11)x(1) ( t - tau(11) ) + a(12)x(2) ( t - tau(12) ) ] x '(2) ( t ) = x(2) ( t ) [ r(2) - a(2)x(2) ( t ) + a(21)x(1) ( t - tau(21) ) + a(22)x(2) ( t - tau(22) ) ] is considered.With intraspecific competition, it is proved that in competitive case, the system is permanent if and only if the interaction matrix of the system satisfies condition (C1) and in cooperative case it is proved that condition (C2) is sufficient for the permanence of the system.