Investigation of spatiotemporal distribution and formation mechanisms of ozone pollution in eastern Chinese cities applying convolutional neural network.

Severe ground-level ozone (O3) pollution over major Chinese cities has become one of the most challenging problems, which have deleterious effects on human health and the sustainability of society. This study explored the spatiotemporal distribution characteristics of ground-level O3 and its precursors based on conventional pollutant and meteorological monitoring data in Zhejiang Province from 2016 to 2021. Then, a high-performance convolutional neural network (CNN) model was established by expanding the moment and the concentration variations to general factors. Finally, the response mechanism of O3 to the variation with crucial influencing factors is explored by controlling variables and interpolating target variables. The results indicated that the annual average MDA8-90th concentrations in Zhejiang Province are higher in the northern and lower in the southern. When the wind direction (WD) ranges from east to southwest and the wind speed (WS) ranges between 2 and 3 m/sec, higher O3 concentration prone to occur. At different temperatures (T), the O3 concentration showed a trend of first increasing and subsequently decreasing with increasing NO2 concentration, peaks at the NO2 concentration around 0.02 mg/m3. The sensitivity of NO2 to O3 formation is not easily affected by temperature, barometric pressure and dew point temperature. Additionally, there is a minimum [Formula: see text] at each temperature when the NO2 concentration is 0.03 mg/m3, and this minimum [Formula: see text] decreases with increasing temperature. The study explores the response mechanism of O3 with the change of driving variables, which can provide a scientific foundation and methodological support for the targeted management of O3 pollution.

Are behavioral interventions a better choice for atopic dermatitis patients? A meta-analysis of 6 randomized controlled trials

Abstract Background The treatment for atopic dermatitis (AD) has been the focus of clinical research, and behavioral intervention is considered an indispensable treatment method. To our knowledge, no relevant meta-analysis has evaluated the effects of behavioral interventions on atopic dermatitis. Objectives To evaluate the effects of behavioral interventions on atopic dermatitis. Methods The authors searched PubMed, EMBASE, and Cochrane CENTRAL to retrieve relevant RCTs (up to Feb 2022). The search strategy involved a combination of related keywords. The Cochrane Q and I2 statistics were used to assess heterogeneity. Results Six RCTs involving seven reports with 246 patients were included. The results suggested that behavioral interventions could relieve eczema severity (correlation coefficient [r = −0.39]; p < 0.001) and scratching severity significantly (r = −0.19; p = 0.017), while not affect itching intensity (r = −0.02; p = 0.840). A sensitivity analysis confirmed the robustness of the results. Study limitations An important limitation of this study was the insufficient number of RCTs and the limited sample size. In addition, the study lacked a control group receiving a type of intervention other than the experimental protocol. Another limitation was the short duration of follow-up. Conclusions This study suggests that behavioral interventions could be effective in treating atopic dermatitis by reducing eczema and scratching severity. Additionally, habit-reversal behavioral therapy may be more effective for treating atopic dermatitis.

Observation of dynamic non-Hermitian skin effects.

Non-Hermitian physics has emerged as a new paradigm that profoundly changes our understanding of non-equilibrium systems, introducing novel concepts such as exceptional points, spectral topology, and non-Hermitian skin effects (NHSEs). Most existing studies focus on non-Hermitian eigenstates, whereas dynamic properties have been discussed only recently, and the dynamic NHSEs are not yet confirmed in experiments. Here, we report the experimental observation of non-Hermitian skin dynamics using tunable one-dimensional nonreciprocal double-chain mechanical systems with glide-time symmetry. Remarkably, dynamic NHSEs are observed with various behaviors in different dynamic phases, which can be understood via the generalized Brillouin zone and the related concepts. Moreover, the observed dynamic NHSEs, amplifications, bulk unidirectional wave propagation, and boundary wave trapping provide promising ways to manipulate waves in a controllable and robust way. Our findings open a new pathway toward non-Hermitian dynamics, which will fertilize the study of non-equilibrium phases of matter.

True-solution-scale utilization of natural chlorophyll a in aqueous media through cooperative aggregation with phycocyanin.

The challenge of applying chlorophyll(Chl) in aqueous media has been a significant obstacle to the diversified development of Chl a-related industries. This study presents the first report on the true-solution-scale utilization of Chl in aqueous media through the construction of chlorophyll a-phycocyanin (Chls-PC) composite nanoparticles. This study determined the optimal conditions for Chls-PC preparation: a composite ratio of 1:25, a solvent ratio of 1:4, and a stirring time of 1 h. Fluorescence spectroscopy, transmission electron microscope, and confocal microscopy confirmed Chl a and PC aggregation. Surface hydrophobicity and contact angle measurements showed that Chls-PC water solubility was similar to PC and much higher than Chl. Infrared spectroscopy, quantum chemical calculations, X-ray photoelectron spectroscopy, and molecular dynamics simulations elucidated the water solubilization mechanism of Chls-PC both experimentally and theoretically. This research provides theoretical guidance for the development and production of water-based products using Chl as a raw material.

A sensitive fluorescence assay of serum dipeptidyl peptidase IV activity to predict the suitability of its inhibitors in patients with type 2 diabetes mellitus.

DPP-IV inhibitors, which are close to the natural hypoglycemic pathway of human physiology and have few side effects, have been extensively employed in the management of type 2 diabetes mellitus (T2DM). However, there are currently no specific blood indicators that can indicate or predict a patient's suitability for DPP-IV inhibitors. In this study, based on the self-developed high-specificity fluorescent substrate glycyl-prolyl-N-butyl-4-amino-1, 8-naphthimide (GP-BAN), a detection method of human serum DPP-IV activity was established and optimized. The method demonstrates a favorable lower limit of detection (LOD) at 0.32 ng/mL and a satisfactory lower limit of quantification (LOQ) of 1.12 ng/mL, and can be used for the detection of DPP-IV activity in trace serum (2 µL). In addition, Vitalliptin and Sitagliptin showed similar IC50 values when human recombinant DPP-IV and human serum were used as enzyme sources, and the intra-day and inter-day precision obtained by the microplate analyzer were less than 15 %. These results indicate that the microplate reader based detection technique has good accuracy, repeatability and reproducibility. A total of 700 volunteers were recruited, and 646 serum samples were tested for DPP-IV activity. The results showed that serum DPP-IV activity was higher in patients with T2DM than in controls (P < 0.01). However, the statistical data of family history of diabetes, gender and age of diabetic patients showed no statistical significance, and there was no contrast difference. The DPP-IV activity of serum in T2DM patients ranged from 2.4 µmol/min/L to 78.6 µmol/min/L, with a huge difference of up to 32-fold. These results suggest that it is necessary to test DPP-IV activity in patients with T2DM when taking DPP-IV inhibitors to determine the applicability of DPP-IV inhibitors in T2DM patients. These results suggest that it is necessary to detect the activity of DPP-IV in blood before taking DPP-IV inhibitors in patients with T2DM to judge the applicability of DPP-IV inhibitors in patients with T2DM.

LSPR-enhanced photoresponsive antibacterial efficiency of Bi/MoS2-loaded fibrin gel for management of diabetic wounds.

Chronic diabetic wounds present formidable challenges, marked by uncontrolled bacterial infections, prolonged inflammation, and impaired angiogenesis. The evolving landscape of photo-responsive antibacterial therapy holds great promise in addressing these multifaceted issues, with a particular focus on leveraging the distinctive properties of 2D heterojunction materials. In this investigation, we engineered composite sprayed hydrogels, seamlessly integrating Bi/MoS2 nano-heterojunctions. Capitalizing on the synergistic interplay between photocatalytic antibacterial and photothermal antibacterial mechanisms, the Bi/MoS2 heterojunction, guided by its localized surface plasmon resonance, demonstrated outstanding antibacterial efficacy within a mere 10-minute exposure to 808 nm near-infrared light. This accelerated sterilization both in vitro and in vivo, consequently expediting wound healing. The sprayed composite gel not only furnishes protective shielding for skin tissues but also fosters endothelial cell proliferation, vascularization, and angiogenesis. This safe and ultrafast sterilizing hydrogel presents immense potential for application in antimicrobial dressings, thereby offering a promising avenue for diabetic wound healing.

[Clinical advantage staging and underlying mechanisms of Wangbi Tablets against knee osteoarthritis based on "disease-formula" interaction network].

The clinical advantage staging and underlying mechanisms of Wangbi Tablets against knee osteoarthritis(KOA) were studied based on the "disease-formula" interaction network. Firstly, the clinical symptoms and related genes corresponding to Wangbi Tablets and KOA in the acute, remission, and recovery phases were collected from clinical guidelines/consensus and SoFDA database, and the putative targets of Wangbi Tablets were obtained from ETCM 2.0. Then, Jaccard similarity and cosine similarity were employed to assess the similarities of clinical symptoms, genes, and enriched pathways between Wangbi Tablets and KOA in different phases. The "disease-formula" interaction network of the drug targets and disease genes was constructed, and the key targets were screened by topological feature calculation. KEGG and Reactome database were used for the functional enrichment of the key targets, on the basis of which the functional characteristics of Wangbi Tablets against KOA in the acute, remission, and recovery phases were predicted. Finally, the SW1353 cells exposed to lipopolysaccharide were used to decipher the mechanism of Wangbi Tablets against KOA. The results showed that 92/3 921, 138/3 708, 139/3 800, and 196/3 946 clinical symptoms and the related genes corresponded to KOA in the acute, remission, and recovery phases and Wangbi Tablets were collected from SoFDA, and 260 putative targets of Wangbi Tablets were obtained from ETCM 2.0. Wangbi Tablets had highest similarity of clinical symptoms, genes, and enriched pathways with KOA in the remission phase and the secondary highest similarity with KOA in the recovery phase. The key targets of Wangbi Tablets mainly participated in the regulation of immunity-inflammation imbalance and exerted pain-relieving and bone-protecting effects to alleviate symptoms such as knee joint pain, joint swelling, soreness, fatigue, and dysfunction. Intriguingly, the key targets of Wangbi Tablets possessed antioxidant effects during KOA in the acute and remission phases, while they maintained material and energy metabolism homeostasis and protected vessels during KOA in the recovery phase. The cell experiment indicated that Wangbi Tablets down-regulated the expression of interleukin(IL)-6, IL-1ß, tumor necrosis factor-α(TNF-α), and Bcl-2-associated X protein(Bax)/B-cell lymphoma 2(Bcl-2) via regulating the phosphatidylinositol 3-kinase(PI3K)-protein kinase B(Akt) signaling pathway. The findings lay a theoretical foundation for further clarifying the clinical advantage stage and precise clinical application of Wangbi Tablets in treating KOA.

A GAN-based fast focusing method for circular SAR images.

Circular Synthetic Aperture Radar(CSAR) imaging is vulnerable to perturbations in the atmosphere and various other elements that can lead to position offset errors in the antenna's phase center as well as induce motion errors. Traditional phase compensation methods that operate in the time domain, such as Auto-regressive Back-projection (ARBP), typically require computation on a direction-by-direction basis, which can result in the considerable expenditure of time and memory resources. To address these challenges, thispaperintroduces a novel approach for focusing on CSAR images. This method leverages the training of a Generative Adversarial Network (GAN) to directly achieve focus on CSAR sub-aperture images. Additionally, to counteract the network's tendency towards low-frequency preferences, the Auto-focus Frequency Loss (AFFL) is introduced. Moreover, to enhance the accuracy of focus position extraction, the Focus Position Feature Attention (FPFA) is proposed. These innovations, along with a new fusion strategy for the sub-aperture images post-focusing, have been experimentally validated, demonstrating significant improvements in the efficiency and accuracy of CSAR image focusing.

Three-dimensional-printed femoral diaphysis for biomechanical testing-Optimization and validation.

Polylactic acid (PLA) models of normal human femoral diaphyses were designed using three-dimensional (3D) printing technology to create inexpensive, accessible, and reproducible specimens for flexural biomechanical studies. These models were subjected to three-point bending and their response to loading was characterized. The anisotropic mechanical behavior of the 3D-printed femurs and the influence of printing orientations, infill density, wall layers, resolution, and other printing parameters were explored to develop a design space. The objective of the design space was set to emulate the flexural biomechanical response of the normal human femur bones. Results show the 3D-printed PLA diaphyseal femurs with 5% infill density, two-four wall layers, and a resolution of 200 µm resulted in a flexural strength of 184.8 ± 8.18 MPa. Models with 20% infill density and six wall layers resulted in a flexural modulus of 18.54 ± 0.543 GPa. These results emulate the biomechanical response of the normal human femur, as determined by historical target values derived from prior cadaveric and 3D printing data. With further research, inclusive of modeling the proximal and distal femur and more comprehensive biomechanical testing, 3D-printed femurs may ultimately serve as a cheap, accessible biomechanical resource for surgeons and researchers.

The Protective Effect of Octanoic Acid on Sepsis: A Review.

Sepsis, a systemic inflammation that occurs in response to a bacterial infection, is a significant medical challenge. Research conducted over the past decade has indicated strong associations among a patient's nutritional status, the composition of their gut microbiome, and the risk, severity, and prognosis of sepsis. Octanoic acid (OA) plays a vital role in combating sepsis and has a protective effect on both animal models and human patients. In this discussion, the potential protective mechanisms of OA in sepsis, focusing on its regulation of the inflammatory response, immune system, oxidative stress, gastrointestinal microbiome and barrier function, metabolic disorders and malnutrition, as well as organ dysfunction are explored. A comprehensive understanding of the mechanisms by which OA act may pave the way for new preventive and therapeutic approaches to sepsis.

The Efficacy of Curcumin Application to Melanoma in Mice: A Systematic Review and Meta-analysis.

OBJECTIVE: Melanoma is a skin tumor that poses a serious threat to human health. Our study explores the effectiveness and safety of curcumin in the treatment of melanoma based on animal models, and providing evidence-based medical evidence for curcumin in the treatment of malignant melanoma. METHODS: The study collected all randomized controlled trial data from the establishment of the database to October 2023 of curcumin for the treatment of melanoma in mice by searching PubMed, Embase, and the Cochrane Library. According to inclusion and exclusion criteria, data were extracted and quality assessment of included studies was performed by using the SYRCLE (Systematic Review Center for Laboratory animal Experimentation) animal experiment bias risk assessment tool. RevMan 5.4 and Stata 15.1 software were used for meta-analysis. RESULTS: Eighteen randomized controlled trials were included in this study with a total of 185 mouse models, including 93 mice in the experimental group and 92 in the control group. The results of meta-analysis showed that the IC50 (inhibitory concentrations of 50%) in the experimental group is lower than that of the control group [standardized mean difference (SMD) = -4.68, 95% confidence interval (CI) (-7.30, -2.06), P < 0.01]; the tumor volume is significantly smaller than the control group [SMD = -3.10, 95% CI (-4.45, -1.75), P < 0.01]; the tumor weight is smaller than the control group [SMD = -3.01, 95% CI (-4.81, -1.21), P < 0.01]. However, there was no significant statistical difference in the apoptosis rate between the experimental group and the control group [SMD = 2.27, 95% CI (-1.39, 5.92), P < 0.01]. CONCLUSION: Based on animal models for meta-analysis, curcumin can inhibit the growth and proliferation of melanoma in mice. Melanoma may be an effective method for treating melanoma. However, this result still requires further in-depth research.

Study on rock fracture mechanism and hydraulic fracturing propagation law of heterogeneous tight sandstone reservoir.

Hydraulic fracturing technology is an effective way to develop tight sandstone reservoirs with low porosity and permeability. The tight sandstone reservoir is heterogeneous and the heterogeneity characteristics has an important influence on fracture propagation. To investigate hydraulic fracture performance in heterogeneous tight reservoir, the X-ray diffraction experiments are carried out, the Weibull distribution method and finite element method are applied to establish the uniaxial compression model and the hydraulic fracture propagation model of heterogeneous tight sandstone. Meanwhile, the sensitivity of different heterogeneity characterization factors and the multi-fracture propagation mechanism during hydraulic fracture propagation is analyzed. The results indicate that the pressure transfer in the heterogeneous reservoir is non-uniform, showing a multi-point initiation fracture mode. For different heterogeneity characterization factors, the heterogeneity characteristics based on elastic modulus are the most sensitive. The multi-fracture propagation of heterogeneous tight sandstone reservoir is different from that of homogeneous reservoir, the fracture propagation morphology is more complex. With the increase of stress difference, the fracture propagation length increases. With the increase of injection rate, the fracture propagation length increases. With the increase of cluster spacing, the propagation length of multiple fractures tends to propagate evenly. This study clarifies the influence of heterogeneity on fracture propagation and provides some guidance for fracturing optimization of tight sandstone reservoirs.

miR-93-5p impairs autophagy-lysosomal pathway via TET3 after subarachnoid hemorrhage.

Intact autophagy-lysosomal pathway (ALP) in neuronal survival is crucial. However, it remains unclear whether ALP is intact after subarachnoid hemorrhage (SAH). Ten-eleven translocation (TET) 3 primarily regulates genes related to autophagy in neurons in neurodegenerative diseases. This study aims to investigate the role of TET3 in the ALP following SAH. The results indicate that the ALP is impaired after SAH, with suppressed autophagic flux and an increase in autophagosomes. This is accompanied by a decrease in TET3 expression. Activation of TET3 by α-KG can improve ALP function and neural function to some extent. Silencing TET3 in neurons significantly inhibited the ALP function and increased apoptosis. Inhibition of miR-93-5p, which is elevated after SAH, promotes TET3 expression. This suggests that the downregulation of TET3 after SAH is, at least in part, due to elevated miR-93-5p. This study clarifies the key role of TET3 in the functional impairment of the ALP after SAH. The preliminary exploration revealed that miR-93-5p could lead to the downregulation of TET3, which could be a new target for neuroprotective therapy after SAH.

Rescue of dead MnO2 for stable electrolytic Zn-Mn redox-flow battery: a metric of mediated and catalytic kinetics.

The virtues of electrolytic MnO2 aqueous batteries are high theoretical energy density, affordability and safety. However, the continuous dead MnO2 and unstable Mn2+/MnO2 electrolysis pose challenges to the practical output energy and lifespan. Herein, we demonstrate bifunctional cationic redox mediation and catalysis kinetics metrics to rescue dead MnO2 and construct a stable and fast electrolytic Zn-Mn redox-flow battery (eZMRFB). Spectroscopic characterizations and electrochemical evaluation reveal the superior mediation kinetics of a cationic Fe2+ redox mediator compared with the anionic ones (e.g. I- and Br-), thus eliminating dead MnO2 effectively. With intensified oxygen vacancies, density functional theory simulations of the reaction pathways further verify the concomitant Fe-catalysed Mn2+/MnO2 electrolysis kinetics via charge delocalization and activated O 2p electron states, boosting its rate capability. As a result, the elaborated eZMRFB achieves a coulombic efficiency of nearly 100%, ultra-high areal capacity of 80 mAh cm-2, rate capability of 20 C and a long lifespan of 2500 cycles. This work may advance high-energy aqueous batteries to next-generation scalable energy storage.

Abrocitinib Monotherapy for Refractory Prurigo Nodularis: Report of Two Successful Cases.

Prurigo nodularis (PN) is a debilitating chronic neuroimmunologic skin condition due to the intense pruritus and difficult to treat. The pruritogenic cytokines, particularly IL-4, IL-13, IL-22, IL-31, and oncostatin M (OSM), play a crucial role in the pathogenesis of PN, potentially involving the JAK1-STAT pathway. An oral JAK1 inhibitor, abrocitinib, is presently undergoing Phase 2 trials for the treatment of PN. We evaluated the efficacy of abrocitinib at a daily dosage of 100 mg in treating two patients with PN affecting both lower limbs: a 50-year-old male with a 16-year disease history and a 38-year-old female with over three years of disease history, both of whom had failed to respond to multiple conventional treatments. Both patients responded rapidly after one week of treatment and exhibited a marked improvement. Following eight weeks of therapy, near-complete resolution of both pruritus and lesions was achieved, and no adverse effects were reported. Additionally, there were no reported side effects during the initial four months of continued treatment. Abrocitinib is an effective targeted therapy for PN, offering a promising new option for refractory patients.

Exploring Embodied Cognition and Brain Dynamics under Multi-tasks Target Detection in Immerse Projector-based Augmented Reality (IPAR) Scenarios.

Embodied cognition explores the intricate interaction between the brain, body, and the surrounding environment. The advancement of mobile devices, such as immersive interactive computing and wireless electroencephalogram (EEG) devices, has presented new challenges and opportunities for studying embodied cognition. To address how mobile technology within immersive hybrid settings affects embodied cognition, we propose a target detection multitask incorporating mixed body movement interference and an environmental distraction light signal. We aim to investigate human embodied cognition in immersive projector-based augmented reality (IPAR) scenarios using wireless EEG technology. We recruited and engaged fifteen participants in four multitasking conditions: standing without distraction (SND), walking without distraction (WND), standing with distraction (SD), and walking with distraction (WD). We pre-processed the EEG data using Independent Component Analysis (ICA) to isolate brain sources and K-means clustering to categorize Independent Components (ICs). Following that, we conducted time-frequency and correlation analyses to identify neural dynamics changes associated with multitasking. Our findings reveal a decline in behavioral performance during multitasking activities. We also observed decreases in alpha and beta power in the frontal and motor cortex during standing target search tasks, decreases in theta power, and increases in alpha power in the occipital lobe during multitasking. We also noted perturbations in theta band power during distraction tasks. Notably, physical movement induced more significant fluctuations in the frontal and motor cortex than distractions from social environment light signals. Particularly in scenarios involving walking and multitasking, there was a noticeable reduction in beta suppression. Our study underscores the importance of brain-body collaboration in multitasking scenarios, where the simultaneous engagement of the body and brain in complex tasks highlights the dynamic nature of cognitive processes within the framework of embodied cognition. Furthermore, integrating immersive augmented reality technology into embodied cognition research enhances our understanding of the interplay between the body, environment, and cognitive functions, with profound implications for advancing human-computer interaction and elucidating cognitive dynamics in multitasking.

Pregnancy in women with a Fontan circulation: Short and long-term outcomes.

BACKGROUND: The Fontan circulation procedure is the palliative surgery of choice for patients with single ventricle physiology, many of whom are now reaching childbearing age due to advances in care. Our study examines the impact of pregnancy on women with Fontan circulation, assessing both short and long-term outcomes. METHODS: We retrospectively analysed pregnancies in women with Fontan circulation at our centre from 2005 to 2023, including a matched non-pregnant, nulliparous cohort for comparison. Pregnancies lost before 18 weeks were analysed separately. RESULTS: Among 26 pregnancies in 18 women, preterm births were common (73.1%), with 3 fetal losses and no maternal deaths. Neonatal complications included a 50% incidence of babies small for gestational age (SGA). Cardiac events occurred in 19.2% of pregnancies, primarily supraventricular arrhythmias, and 23% experienced postpartum haemorrhage. Over a median 6.1 [5.2-10.6]-year follow-up, no deaths, heart failure (HF), or Fontan-associated liver disease (FALD) developed, and functional status remained stable. CONCLUSIONS: Women with a Fontan-type circulation undergoing pregnancy had a few serious maternal cardiac events, though there was a high rate of post-partum haemorrhage. The rates of neonatal complications, particularly related to restricted growth and pre-term birth, were also high. Our findings indicate a generally positive medium-term outlook for these patients, though the impact of pregnancy on long-term survival remains unclear. Careful selection of patients with Fontan circulation during pre-pregnancy counselling may help to reduce complications during and after pregnancy.

Research on the damage and wound repair of cornea by GO and ZnO.

OBJECTIVE: The widespread use of nanoparticles in recent years has increased the risk of ocular exposure. zinc oxide (ZnO) is widely used in the field of cosmetics because of its unique chemical properties. The application of graphene oxide (GO) as an emerging nanomaterial in the field of eye drops is also gradually emerging. Currently, research on ZnO and GO eye exposure mainly focuses on application or toxicity to optic nerve cells. There's less study on corneal wound healing effects. and the previous research hasn't compared ZnO and GO corneal toxicity. METHODS: We systematically established a complete chain study of in vitro and in vivo experiments and mouse corneal injury model, and comprehensively evaluated the ocular safety and toxicity of ZnO and GO. RESULTS: We found that 50 ug/mL GO and 0.5 ug/mL ZnO can reduce human corneal epithelial cells (HCEpiC) viability in a concentration-dependent manner. Short-term repeated exposure to ZnO can cause sterile inflammation of the cornea with concentration-dependence, while GO have not been significantly altered. 50 ug/mL ZnO could significantly delay the healing of corneal wounds, while GO did not change wound healing. CONCLUSION: The toxic effect of ZnO is higher than that of GO. Inflammatory signal transduction, oxidative stress and apopnano zitosis are involved in the ocular toxicity injury process of nanoparticles. Research can provide a judgement basis for people's eye health and eye protection risk control.

Ultrabroadband nonlinear enhancement of mid-infrared frequency upconversion in hyperbolic metamaterials.

Metamaterials have demonstrated significant potential for enhancing nonlinear processes at the nanoscale. The presence of narrowband hot-spots and highly inhomogeneous mode-field distributions often limit the enhancement of nonlinear interactions over larger spatial scales. This has posed a formidable challenge in achieving simultaneous enhancement across a broadband spectral range, significantly constraining the potential of photonic nanostructures in enhancing nonlinear frequency conversion. Here, we propose a broadband resonant mode matching method through near-field examinations that supports the multipole modes and enables the development of an ultrabroadband-enhanced 3-5 µm mid-infrared frequency upconversion technique utilizing a hyperbolic triangular pyramidal metasurface. The gap-plasma mode of the hyperbolic metamaterial multilayer system excites narrowly high-order resonances at near-infrared pump light wavelengths, while the slow-light effect generated by the dipoles achieves ultrabroadband near-field enhancement at mid-infrared wavelengths. The symmetry breaking of the triangular structure localizes these resonant modes at the tips, enabling mode-matched modulation at different wavelengths, and thus boosting the nonlinear frequency conversion process. Our approach provides a promising platform for metasurface-based frequency conversion techniques.