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1.
Nature ; 613(7943): 324-331, 2023 01.
Article in English | MEDLINE | ID: mdl-36599989

ABSTRACT

Pathogens generate ubiquitous selective pressures and host-pathogen interactions alter social behaviours in many animals1-4. However, very little is known about the neuronal mechanisms underlying pathogen-induced changes in social behaviour. Here we show that in adult Caenorhabditis elegans hermaphrodites, exposure to a bacterial pathogen (Pseudomonas aeruginosa) modulates sensory responses to pheromones by inducing the expression of the chemoreceptor STR-44 to promote mating. Under standard conditions, C. elegans hermaphrodites avoid a mixture of ascaroside pheromones to facilitate dispersal5-13. We find that exposure to the pathogenic Pseudomonas bacteria enables pheromone responses in AWA sensory neurons, which mediate attractive chemotaxis, to suppress the avoidance. Pathogen exposure induces str-44 expression in AWA neurons, a process regulated by a transcription factor zip-5 that also displays a pathogen-induced increase in expression in AWA. STR-44 acts as a pheromone receptor and its function in AWA neurons is required for pathogen-induced AWA pheromone response and suppression of pheromone avoidance. Furthermore, we show that C. elegans hermaphrodites, which reproduce mainly through self-fertilization, increase the rate of mating with males after pathogen exposure and that this increase requires str-44 in AWA neurons. Thus, our results uncover a causal mechanism for pathogen-induced social behaviour plasticity, which can promote genetic diversity and facilitate adaptation of the host animals.


Subject(s)
Caenorhabditis elegans , Pheromones , Pseudomonas aeruginosa , Reproduction , Sexual Behavior, Animal , Animals , Female , Male , Caenorhabditis elegans/metabolism , Caenorhabditis elegans/microbiology , Caenorhabditis elegans/physiology , Caenorhabditis elegans Proteins/metabolism , Glycolipids/metabolism , Hermaphroditic Organisms/physiology , Pheromones/metabolism , Pseudomonas aeruginosa/pathogenicity , Pseudomonas aeruginosa/physiology , Receptors, Pheromone/metabolism , Reproduction/physiology , Sensory Receptor Cells/metabolism
2.
PLoS Genet ; 18(1): e1010029, 2022 01.
Article in English | MEDLINE | ID: mdl-35100258

ABSTRACT

Olfactory integration is important for survival in a natural habitat. However, how the nervous system processes signals of two odorants present simultaneously to generate a coherent behavioral response is poorly understood. Here, we characterize circuit basis for a form of olfactory integration in Caenorhabditis elegans. We find that the presence of a repulsive odorant, 2-nonanone, that signals threat strongly blocks the attraction of other odorants, such as isoamyl alcohol (IAA) or benzaldehyde, that signal food. Using a forward genetic screen, we found that genes known to regulate the structure and function of sensory neurons, osm-5 and osm-1, played a critical role in the integration process. Loss of these genes mildly reduces the response to the repellent 2-nonanone and disrupts the integration effect. Restoring the function of OSM-5 in either AWB or ASH, two sensory neurons known to mediate 2-nonanone-evoked avoidance, is sufficient to rescue. Sensory neurons AWB and downstream interneurons AVA, AIB, RIM that play critical roles in olfactory sensorimotor response are able to process signals generated by 2-nonanone or IAA or the mixture of the two odorants and contribute to the integration. Thus, our results identify redundant neural circuits that regulate the robust effect of a repulsive odorant to block responses to attractive odorants and uncover the neuronal and cellular basis for this complex olfactory task.


Subject(s)
Caenorhabditis elegans/physiology , Sensory Receptor Cells/physiology , Smell/physiology , Animals , Caenorhabditis elegans/genetics , Ketones/pharmacology , Mutation , Odorants , Pentanols/pharmacology , Smell/drug effects
3.
J Am Chem Soc ; 146(6): 4242-4251, 2024 Feb 14.
Article in English | MEDLINE | ID: mdl-38300828

ABSTRACT

Understanding the reconstruction of electrocatalysts under operational conditions is essential for studying their catalytic mechanisms and industrial applications. Herein, using spatiotemporally resolved Raman spectroscopy with CO as a probe molecule, we resolved the spontaneous reconstruction of Cu active sites during cathodic CO reduction reactions (CORRs). Quasi-in situ focused ion beam transmission electron microscopy (FIB-TEM) revealed that under prolonged electrolysis, the Cu surface can reconstruct to form nanometer-sized Cu particles with (111)/(100) facets and abundant grain boundaries, which strongly favor the formation of an inactive *CObridge binding site and deteriorate the CORR performance. A short period of anodic oxidation can efficiently remove these reconstructed nanoparticles by quick dissolution of Cu, thus providing an effective strategy to regenerate the Cu catalysts and recover their CORR performance. This study provides real-time in situ observations of Cu reconstruction and changes in the binding of key reaction intermediates, highlighting the decisive role of the local active site, rather than the macroscopic morphology, on adsorption of key reaction intermediates and thus CORR performance.

4.
J Am Chem Soc ; 146(26): 17618-17623, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38899905

ABSTRACT

Upconversion (UC) of incoherent near-infrared (NIR) photons to visible photons through sensitized triplet-triplet annihilation (TTA) shows great potential in solar energy harvesting, photocatalysis, and bioimaging. However, the efficiencies of NIR-to-visible TTA-UC systems lag considerably behind those of their visible-to-visible counterparts. Here, we report a novel NIR-to-yellow TTA-UC system with a record quantum yield (QY) of 21.1% (out of a 100% maximum) and a threshold intensity of 20.2 W/cm2 by using InAs-based colloidal quantum dots (QDs) as triplet photosensitizers. The key to success is the epitaxial growth of an ultrathin ZnSe shell on InAs QDs that passivates the surface defects without impeding triplet energy transfer (TET) from QDs to surface-bound tetracene. Transient absorption spectroscopy verifies efficient TET efficiency of more than 80%, along with sufficiently long triplet lifetime of tetracene molecules, leading to high-performance UC. Moreover, high UC QYs (>18%) remain when larger InAs-based QDs─of which the absorption peak is red-shifted by more than 50 nm─are used as sensitizers, indicating the great potential of InAs QDs to utilize NIR photons with lower energy.

5.
Opt Express ; 32(10): 16611-16628, 2024 May 06.
Article in English | MEDLINE | ID: mdl-38858863

ABSTRACT

A scheme for high-efficiency transfer of optical vortices is proposed by an inelastic two-wave mixing (ITWM) process in an inverted-Y four-level atomic medium, which is originally prepared in a coherent superposition of two ground states. The orbital angular momentum (OAM) information in the incident vortex probe field can be transferred to the generated signal field through the ITWM process. Choosing reasonable experimentally realizable parameters, we find that the presence of the off-resonance control field can greatly improve the conversion efficiency of optical vortices, rather than in the absence of a control field. This is caused by the broken of the destructive interference between two one-photon excitation pathways. Furthermore, we also extend our model to an inelastic multi-wave mixing process and demonstrate that the transfer efficiency between multiple optical vortices strongly depends on the superposition of the ground states. Finally, we explore the composite vortex beam generated by collinear superposition of the incident vortex probe and signal fields. It is obvious that the intensity and phase profiles of the composite vortex can be effectively controlled via adjusting the intensity of the control field. Potential applications of our scheme may exist in OAM-based optical communications and optical information processing.

6.
Chemphyschem ; 25(3): e202300599, 2024 Feb 01.
Article in English | MEDLINE | ID: mdl-38012079

ABSTRACT

Two-step deposition method has been widely exploited to fabricate FA1-x Csx PbI3 perovskite solar cells. However, in previous studies, CsI is mainly added into the PbI2 precursor with DMF/DMSO as solvent. Here in this study, a novel method to fabricate FA1-x Csx PbI3 perovskite has been proposed. The CsI is simultaneously added into the PbI2 precursor and the organic FAI/MACl salts solution in our modified two-step deposition process. The resulting FA1-x Csx PbI3 film exhibits larger perovskite crystals and suppressed defect density (4.05×1015  cm-3 ) compared with the reference perovskite film (9.23×1015  cm-3 ) without CsI. Therefore, the obtained FA1-x Csx PbI3 perovskite solar cells have demonstrated superior power conversion efficiencies (PCE=21.96 %) together with better long-term device stability.

7.
Phys Chem Chem Phys ; 26(22): 16096-16106, 2024 Jun 06.
Article in English | MEDLINE | ID: mdl-38780318

ABSTRACT

In this study, we proposed a bifunctional sensor of high sensitivity and slow light based on carbon nanotubes (CNTs). An array of left semicircular ring (LSR), right semicircular ring (RSR), and circular ring (CR) resonators are utilized to form the proposed metamaterial. The proposed structure can achieve double plasmon-induced transparency (PIT) effects under the excitation of a TM-polarization wave. The double PIT originated from the destructive interference between two bright modes and a dark mode. A coupled harmonic oscillator model is used to describe the destructive interference between the two bright modes and a dark mode, and the simulation results agree well with the calculated results. Moreover, we investigate the influence of the coupling distance, period, and flare angle on the PIT spectra. The relationship between the resonant frequencies, full width at half maximum (FWHM), amplitudes, quality factors (Q), and the coupling distance is also studied. Finally, a high sensitivity of 1.02 THz RIU-1 is obtained, and the transmission performance can be maintained at a good level when the incident angle is less than 40°. Thus, the sensor can cope with situations where electromagnetic waves are not perpendicular to the structure's surface. The maximum figure of merit (FOM) can reach about 8.26 RIU-1; to verify the slow light property of the device, the slow light performance of the proposed structure is investigated, and a maximum time delay (TD) of 22.26 ps is obtained. The proposed CNT-based metamaterial can be used in electromagnetically induced transparency applications, such as sensors, optical memory devices, and flexible terahertz functional devices.

8.
Phys Chem Chem Phys ; 26(17): 13209-13218, 2024 May 01.
Article in English | MEDLINE | ID: mdl-38630493

ABSTRACT

In this paper, we propose a borophene-based grating structure (BBGS) to realize multi-band plasmon-induced absorption. The coupling of two resonance modes excited by upper borophene grating (UBG) and lower borophene grating (LBG) leads to plasmon-induced absorption. The coupled-mode theory (CMT) is utilized to fit the absorption spectrum. The simulated spectrum fits well with the calculated result. We found the absorption peaks exhibit a blue shift with an increase in the carrier density of borophene grating. Further, as the coupling distance D increases, the first absorption peak shows a blue shift, while the second absorption peak exhibits a red shift, leading to a smaller reflection window. Moreover, the enhancement absorption effect caused by the bottom PEC layer is also analyzed. On this basis, using a three-layer borophene grating structure, we designed a three-band perfect absorber with intensities of 99.83%, 99.45%, and 99.96% in the near-infrared region. The effect of polarization angle and relaxation time on the absorption spectra is studied in detail. Although several plasmon-induced absorption based on two-dimensional (2D) materials, such as graphene, black phosphorus, and transition metal dichalcogenides (TMDs), have been previously reported, this paper proposes a borophene-based metamaterial to achieve plasmon-induced perfect absorption since borophene has some advantages such as high surface-to-volume ratios, mechanical compliance, high carrier mobility, excellent flexibility, and long-term stability. Therefore, the proposed borophene-based metamaterial will be beneficial in the fields of multi-band perfect absorber in the near future.

9.
Phys Chem Chem Phys ; 26(5): 4597-4606, 2024 Jan 31.
Article in English | MEDLINE | ID: mdl-38250817

ABSTRACT

We proposed a triple-band narrowband device based on a metal-insulator-metal (MIM) structure in visible and near-infrared regions. The finite difference time domain (FDTD) simulated results illustrated that the absorber possessed three perfect absorption peaks under TM polarization, and the absorption efficiencies were about 99.76%, 99.99%, and 99.92% at 785 nm, 975 nm, and 1132 nm, respectively. Simulation results matched well with the results of coupled-mode theory (CMT). Analyses of the distributions of the electric field indicated the "perfect" absorption was due to localized surface plasmon polaritons resonance (LSPPR) and Fabry-Perot resonance. We developed a multi-band absorber with more ellipsoid pillars. The four band-absorbing device presented perfect absorption at 767 nm, 1046 nm, 1122 nm, and 1303 nm, and the absorption rates were 99.45%, 99.41%, 99.99%, and 99.94%, respectively. By changing the refractive index of the surrounding medium, the resonant wavelengths could be tuned linearly. The maximum sensitivity and Figure of Merit were 230 nm RIU-1 and 10.84 RIU-1, respectively. The elliptical structural design provides more tuning degrees of freedom. The absorber possessed several satisfactory performances: excellent absorption behavior, multiple bands, tunability, incident insensitivity, and simple structure. Therefore, the designed absorbing device has enormous potential in optoelectronic detection, optical switching, and imaging.

10.
Ecotoxicol Environ Saf ; 270: 115925, 2024 Jan 15.
Article in English | MEDLINE | ID: mdl-38183752

ABSTRACT

Disinfection by-products (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs), have attracted attention due to their carcinogenic properties, leading to varying conclusions. This meta-analysis aimed to evaluate the dose-response relationship and the dose-dependent effect of DBPs on cancer risk. We performed a selective search in PubMed, Web of Science, and Embase databases for articles published up to September 15th, 2023. Our meta-analysis eventually included 25 articles, encompassing 8 cohort studies with 6038,525 participants and 10,668 cases, and 17 case-control studies with 10,847 cases and 20,702 controls. We observed a positive correlation between increased cancer risk and higher concentrations of total trihalomethanes (TTHM) in water, longer exposure durations, and higher cumulative TTHM intake. These associations showed a linear trend, with relative risks (RRs) and 95 % confidence intervals (CIs) being 1.02 (1.01-1.03), 1.04 (1.02-1.06), and 1.02 (1.00-1.03), respectively. Gender-specific analyses revealed slightly U-shaped relationships in both males and females, with males exhibiting higher risks. The threshold dose for TTHM in relation to cancer risk was determined to be 55 µg/L for females and 40 µg/L for males. A linear association was also identified between bladder cancer risk and TTHM exposure, with an RR and 95 % CI of 1.08 (1.05-1.11). Positive linear associations were observed between cancer risk and exposure to chloroform, bromodichloromethane (BDCM), and HAA5, with RRs and 95 % CIs of 1.02 (1.01-1.03), 1.33 (1.18-1.50), and 1.07 (1.03-1.12), respectively. Positive dose-dependent effects were noted for brominated THMs above 35 µg/L and chloroform above 75 µg/L. While heterogeneity was observed in the studies for quantitative synthesis, no publication bias was detected. Exposure to TTHM, chloroform, BDCM, or HAA5 may contribute to carcinogenesis, and the risk of cancer appears to be dose-dependent on DBP exposure levels. A cumulative effect is suggested by the positive correlation between TTHM exposure and cancer risk. Bladder cancer and endocrine-related cancers show dose-dependent and positive associations with TTHM exposure. Males may be more susceptible to TTHM compared to females.


Subject(s)
Disinfectants , Urinary Bladder Neoplasms , Water Pollutants, Chemical , Male , Female , Humans , Disinfection , Chloroform/analysis , Trihalomethanes/toxicity , Trihalomethanes/analysis , Water Pollutants, Chemical/toxicity , Water Pollutants, Chemical/analysis , Disinfectants/toxicity
11.
Carcinogenesis ; 44(2): 143-152, 2023 05 26.
Article in English | MEDLINE | ID: mdl-36455238

ABSTRACT

Lung squamous cell carcinoma (LUSC) lacks appropriate prognostic and diagnostic strategies. Available studies suggest the effectiveness of immunotherapy for LUSC, but effective molecular markers are still insufficient. We obtained mRNA expression and clinical information of LUSC samples from The Cancer Genome Atlas (TCGA) database. Enrichment levels of immune-related genes were revealed by single sample gene set enrichment analysis. Then, differentially expressed genes (DEGs) related to immunity were obtained by differential analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. In addition, Cox regression analysis combined with LASSO method was utilized to identify immune-related prognostic genes, and an immune-related prognostic model was constructed. Kaplan-Meier and receiver operating characteristic (ROC) curves were drawn to verify the accuracy of the model. Finally, a nomogram and calibration curve were drawn to predict LUSC patients' survival. Samples were assigned into high-, medium- and low-immune groups. Compared with low- and medium-immune groups, high-immune group enriched more immune cells, with higher immune infiltration degree, and higher expression of immune checkpoints and human leukocyte antigen. DEGs were enriched in biological processes and signaling pathways related to immunity. Eleven genes (ONECUT3, MAGED4, SULT2A1, HPR, S100A5, IRS4, DPP6, FGF8, TEX38, PLAAT1 and CLEC3A) were obtained to construct an immune-related prognostic model. Riskscore served as an independent prognostic factor. Besides, the nomogram prediction model could predict disease progression in LUSC patients. The constructed risk assessment model for LUSC immune-related genes could assess LUSC patients' prognoses with great efficacy, providing guidance for the clinical treatment of LUSC.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Carcinoma, Squamous Cell , Lung Neoplasms , Humans , Prognosis , Carcinoma, Squamous Cell/genetics , Lung Neoplasms/genetics , Lung , Lectins, C-Type
12.
J Am Chem Soc ; 145(37): 20655-20664, 2023 Sep 20.
Article in English | MEDLINE | ID: mdl-37639564

ABSTRACT

Developing alternative electrolysis techniques is crucial for advancing electrocatalysis in addition to tremendous efforts of material developments. Recently, pulse electrochemical CO2 reduction reaction (CO2RR) has demonstrated dramatic selectivity improvement toward multicarbon (C2+) products compared to potentiostatic electrochemical CO2RR, yet the underlying mechanisms remain little understood. Herein, we develop a fast time-resolved in situ Raman spectroscopic method with a time resolution of 0.25 s. We reveal that pulse electrolysis improves the C2+ selectivity of CO2RR through dynamic controls of the surface CuxO/Cu composition that would be unachievable under potentiostatic electrolysis. The population of the surface-adsorbed CO intermediate (COads) is characterized to be the determining factor in controlling reaction selectivity, which depicts the C2+/C1 selectivity of CO2RR under pulse conditions. Meanwhile, the vibrational character of COads, despite transforming dynamically between the low-frequency and high-frequency modes is characterized not to be the key factor in controlling the reaction selectivity. Such an active control of catalyst surface compositions and reaction intermediates enabled by pulse electrolysis offer a general way of regulating the electrocatalysis performance of broad electrochemical reactions beyond CO2RR.

13.
J Am Chem Soc ; 145(25): 14101-14111, 2023 Jun 28.
Article in English | MEDLINE | ID: mdl-37321595

ABSTRACT

Developing industrial-grade electroreduction of CO2 to produce formate (HCOO-)/formic acid (HCOOH) depends on highly active electrocatalysts. However, structural changes due to the inevitable self-reduction of catalysts result in severe long-term stability issues at industrial-grade current density. Herein, linear cyanamide anion ([NCN]2-)-constructed indium cyanamide nanoparticles (InNCN) were investigated for CO2 reduction to HCOO- with a Faradaic efficiency of up to 96% under a partial current density (jformate) of 250 mA cm-2. Bulk electrolysis at a jformate of 400 mA cm-2 requires only -0.72 VRHE applied potential with iR correction. It also achieves continuous production of pure HCOOH at ∼125 mA cm-2 for 160 h. The excellent activity and stability of InNCN are attributed to its unique structural features, including strongly σ-donating [NCN]2- ligands, the potential structural transformation of [N═C═N]2- and [N≡C-N]2-, and the open framework structure. This study affirms metal cyanamides as promising novel materials for electrocatalytic CO2 reduction, broadening the variety of CO2 reduction catalysts and the understanding of structure-activity relationships.

14.
J Med Virol ; 95(3): e28623, 2023 03.
Article in English | MEDLINE | ID: mdl-36852651

ABSTRACT

We assessed the effectiveness of mRNA and viral-vector vaccines in epidemic period led by different SARS-CoV-2 variants. Systematic search of PubMed, EMBASE, and CNKI (China National Knowledge Infrastructure) databases without language restriction for studies published before September 19, 2022. The review was registered with PROSPERO (CRD42022335430) and reported according to PRISMA guidelines. Forty studies met the inclusion criteria for this study, with 62 954 861 participants. The overall vaccine effectiveness (VE) to prevent COVID-19 infection was 0.76 (95% confidence interval [CI] 0.73-0.78), symptomatic infection was 0.87 (95% CI 0.83-0.91), hospital admissions was 0.82 (95% CI 0.75-0.87), and mortality was 0.76 (95% CI 0.48-0.89). Subgroup analysis were performed to characterize the effectiveness of different vaccines. When SARS-CoV-2 variants are taking account, the VE decreased along with the variation of the virus by clinical outcomes and vaccine types. The findings of this systematic review provide the best available evidence that BNT162b2, mRNA-1273, ChAdOx1, and Ad26. COV2.S seems to be approximately effective from predelta to omicron, but only modestly effective in participants aged 65 or older. When SARS-CoV-2 variants are taking account, VE decreased along with the variation of the virus for all mRNA and viral-vector vaccines.


Subject(s)
COVID-19 , Viral Vaccines , Humans , SARS-CoV-2/genetics , RNA, Messenger , BNT162 Vaccine , COVID-19/epidemiology , COVID-19/prevention & control
15.
Nutr Cancer ; 75(3): 785-794, 2023.
Article in English | MEDLINE | ID: mdl-36715012

ABSTRACT

The anti-inflammatory properties of glucosamine and chondroitin suggest that they may have potential effects in cancer prevention. We performed this meta-analysis to assess the protective function of glucosamine and/or chondroitin intake against cancer risk. We searched the PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI) databases. The odds ratio (OR), corresponding to the 95% confidence interval (95% CI), was used to assess the association between chondroitin and/or glucosamine intake and cancer risk. Thirteen studies met the inclusion criteria, with 1,690,918 participants and 55,045 cancer cases. Overall, chondroitin and/or glucosamine intake was associated with a lower risk of colorectal cancer (OR = 0.91, 95% CI, 0.87-0.94) and lung cancer (OR = 0.84, 95% CI, 0.79-0.89). Subgroup analysis supported the protective effect of different SYSADOAs (chondroitin and/or glucosamine) intake. However, the protective effect was not observed in the only chondroitin intake group and in the NSAIDs group. Our meta-analysis found that the intake of glucosamine and/or chondroitin decreased the risk of colorectal and lung cancers. Moreover, NSAIDs use may have a synergistic protective effect.


Subject(s)
Chondroitin , Lung Neoplasms , Humans , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Chondroitin/therapeutic use , Glucosamine , Lung Neoplasms/prevention & control
16.
Nanotechnology ; 34(24)2023 Mar 24.
Article in English | MEDLINE | ID: mdl-36881863

ABSTRACT

Low-dimensional tin selenide nanoribbons (SnSe NRs) show a wide range of applications in optoelectronics fields such as optical switches, photodetectors, and photovoltaic devices due to the suitable band gap, strong light-matter interaction, and high carrier mobility. However, it is still challenging to grow high-quality SnSe NRs for high-performance photodetectors so far. In this work, we successfully synthesized high-quality p-type SnSe NRs by chemical vapor deposition and then fabricated near-infrared photodetectors. The SnSe NR photodetectors show a high responsivity of 376.71 A W-1, external quantum efficiency of 5.65 × 104%, and detectivity of 8.66 × 1011Jones. In addition, the devices show a fast response time with rise and fall time of up to 43µs and 57µs, respectively. Furthermore, the spatially resolved scanning photocurrent mapping shows very strong photocurrent at the metal-semiconductor contact regions, as well as fast generation-recombination photocurrent signals. This work demonstrated that p-type SnSe NRs are promising material candidates for broad-spectrum and fast-response optoelectronic devices.

17.
Phys Chem Chem Phys ; 25(35): 23855-23866, 2023 Sep 13.
Article in English | MEDLINE | ID: mdl-37641967

ABSTRACT

In this paper, a TM polarization multi-band absorber is achieved in a graphene-Ag asymmetrical grating structure. The proposed absorber can achieve perfect absorption at 1108 nm, 1254 nm, and 1712 nm (the absorption exceeds 98.4% at the three peaks). Results show that the perfect absorption effect originates from the excitation of magnetic polaritons (MPs) in the silver ridge grating; a LC equivalent circuit model is utilized to confirm the finite-difference-time-domain (FDTD) simulation. The influences of the incident angle, polarization angle, and geometrical size on the absorption spectrum are investigated. Moreover, a quadruple band absorber and a quintuple band absorber are also designed by introducing more silver grating ridges in one period. The proposed graphene-Ag asymmetrical structure has some advantages compared with other absorbers such as the ability to be independently tuned and a simple structure. Thus, the proposed structure can be applied in the areas of multiple absorption switches, near-infrared modulators, and sensors.

18.
Phys Chem Chem Phys ; 25(40): 27586-27594, 2023 Oct 18.
Article in English | MEDLINE | ID: mdl-37807903

ABSTRACT

In this paper, we proposed an ultra-broadband and high absorption rate absorber based on Fe materials. The proposed absorber consists of a rectangle pillar, two rings, a SiO2 film, a Ge2Sb2Te5(GST) planar cavity, an Fe mirror, and a SiO2 substrate. The average absorption reaches 98.45% in the range of 400-4597 nm. We investigate and analyze the electric field distributions. The analysis of the physical mechanism behind the broadband absorption effect reveals that it is driven by excited surface plasmons. Furthermore, the absorber can maintain high absorption efficiency under a large incident angle. The geometrical symmetric structure possesses polarization insensitivity properties. The proposed structure allows for certain manufacturing errors, which improves the feasibility of the actual manufacture. Then, we investigate the effect of different materials on absorption. Finally, we study the matching degree between the energy absorption spectrum and the standard solar spectrum under AM 1.5. The results reveal that the energy absorption spectrum matches well with the standard solar spectrum under AM 1.5 over the full range of 400 to 6000 nm. In contrast, energy loss can be negligible. The absorber possesses ultra-broadband perfect absorption, a high absorption rate, and a simple structure which is easy to manufacture. It has tremendous application potential in many areas, such as solar energy capture, thermal photovoltaics, terminal imaging, and other optoelectronic devices.

19.
Phys Chem Chem Phys ; 25(12): 8489-8496, 2023 Mar 22.
Article in English | MEDLINE | ID: mdl-36883439

ABSTRACT

With the development of science and technology, intermediate infrared technology has gained more and more attention in recent years. In the research described in this paper, a tunable broadband absorber based on a Dirac semimetal with a layered resonant structure was designed, which could achieve high absorption (more than 0.9) of about 8.7 THz in the frequency range of 18-28 THz. It was confirmed that the high absorption of the absorber comes from the strong resonance absorption between the layers, and the resonance of the localised surface plasmon. The absorber has a gold substrate, which is composed of three layers of Dirac semimetal and three layers of optical crystal plates. In addition, the resonance frequency of the absorber can be changed by adjusting the Fermi energy of the Dirac semimetal. The absorber also shows excellent characteristics such as tunability, absorption stability at different polarisation waves and incident angles, and has a high application value for use in radar countermeasures, biotechnology and other fields.

20.
J Opt Soc Am A Opt Image Sci Vis ; 40(9): 1706-1713, 2023 Sep 01.
Article in English | MEDLINE | ID: mdl-37707007

ABSTRACT

In this paper, we generate a type of double helico-conical beam (HCB) by binarizing the modified helico-conical phase (MHCP). The diffraction patterns of the double HCBs were analyzed theoretically and experimentally. The relative position of the double HCBs can be adjusted arbitrarily by introducing a blazed grating only. In addition, the superposition of multiple binary MHCPs can be used to generate multi-helix beams. Accordingly, the diffraction patterns of the multi-helix beams were also analyzed theoretically and experimentally. The results demonstrated that the number and relative position of multi-helix beams can be adjusted by the number of superimposed MHCP profiles and the azimuth factor θ j, respectively. This kind of arrayed HCB will be potentially applied in the fields of optical manipulation and multiplexed holography.

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