Multi-band perfect absorber based on an elliptical cavity coupled with an elliptical metal nanorod.

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.

A carbon nanotube metamaterial sensor showing slow light properties based on double plasmon-induced transparency.

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.

Dynamically tunable multi-band plasmon-induced absorption based on multi-layer borophene ribbon gratings.

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.

An ultra-broadband solar absorber based on α-GST/Fe metamaterials from visible light to mid-infrared.

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.

Effect of superior laryngeal nerve block in alleviating sore throat after application of i-gel supraglottic airway: a randomized controlled trial.

BACKGROUND: Postoperative sore throat (POST) is a common complaint after supraglottic airway device (SAD) application. Internal branch of the superior laryngeal nerve (iSLN) block has the potential to alleviate POST. The aim of this trial was to explore the effect of iSLN block in alleviating sore throat, as well as to identify the potential risk factors for POST after SAD insertion. METHODS: One hundred thirty-four patients scheduled for elective gynecological surgery were randomized to either group T: tetracaine syrup (1%) for local lubrication on i-gel supraglottic device (n = 67) or group B: i-gel insertion with water based lubricant on it and followed by bilateral iSLN block (ropivacaine, 0.375%, 2 ml for each side) (n = 67). Under ultrasound guidance, iSLN was exposed below thyrohyoid membrane. The primary outcome was the intensity of sore throat at 6 h after surgery. In addition, POST score at 0.5 h and 24 h, the severity of postoperative swallowing discomfort, acoustic analysis and complications were measured. RESULTS: Compared with tetracaine syrup for local lubrication, iSLN block resulted in a reduced intensity of POST at 0.5 h (P = 0.044, OR = 1.99, 95%CI 1.02 to 3.88) and 6 h (P < 0.001, OR = 5.07, 95%CI 2.53 to 10.14) after surgery, as well as less severity of swallowing discomfort (P < 0.001, OR = 2.21, 95%CI 1.63 to 2.99) and cough (P = 0.039, OR = 1.97, 95%CI 1.04 to 3.73). The patients after iSLN block presented lower jitter and shimmer value in acoustic analysis at 6 h after surgery (P < 0.001). CONCLUSIONS: iSLN block was effective in alleviating POST, improving voice function, as well as reducing postoperative swallowing discomfort and coughing. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR2000037974) on 8th Sept 2020.

Internal branch of superior laryngeal nerve block by dexamethasone alleviates sore throat after thyroidectomy: a randomized controlled trial.

PURPOSE: Postoperative sore throat (POST) is a common complaint following thyroidectomy. Dexamethasone was reported to alleviate POST when administered via different routes. This study aimed to compare the effects of local spray and perineural injection surrounding the internal branch of superior laryngeal nerve (iSLN) in preventing POST and alleviating postoperative impaired voice function. METHODS: A randomized, double-blinded, controlled trial was performed to test the efficacy of the iSLN block in inhibiting of POST. A total of 161 patients who underwent elective thyroidectomy were randomly allocated to two groups. Group Spray: 4 mg dexamethasone was sprayed on to the vocal cord; Group iSLN: bilateral perineural injection with 4 mg dexamethasone around the iSLN. The incidence and severity of POST, swallowing pain, and its side effects were evaluated. Postoperative acoustic analysis, including jitter and shimmer, was also performed. RESULTS: Group iSLN exhibited a significantly less incidence and intensity of POST at 6 h and 24 h (P < 0.001). The patients experienced less swallowing pain at 6 h (P < 0.001) after the surgery, compared with Group Spray. When compared with Group Spray, Group iSLN improved postoperative voice function, which was characterized by lower jitter and lower shimmer value at 6 h and 24 h (P < 0.001) after the surgery. The severity of postoperative cough is higher in Group Spray (P < 0.001). CONCLUSIONS: Among patients undergoing elective thyroidectomy, those who received perineural injection surrounding iSLN with dexamethasone had improved voice function and presented with more excellence in the inhibition of POST and cough, in comparison with the local spray. REGISTER INFORMATION: This trial was registered in the Chinese Clinical Trial Registry on 4th Jan, 2021 (ChiCTR2100042145). The trial is registered at http://www.chictr.org.cn/showproj.aspx?proj=120142 .

Antisense oligodeoxynucleotides against dynamin-related protein 1 reduce remifentanil-induced hyperalgesia by modulating spinal N-methyl-D-aspartate receptor expression in rats.

Background: Spinal N-methyl-D-aspartate (NMDA) receptor activation is attributed to remifentanil-induced hyperalgesia (RIH). However, the specific mechanism and subsequent treatment is still unknown. Previous studies have shown that the dynamin-related protein 1 (DRP1)-mitochondria-reactive oxygen species (ROS) pathway plays an important role in neuropathic pain. This study examined whether antisense oligodeoxynucleotides against DRP1 (AS-DRP1) could reverse RIH. Methods: The authors first measured changes in paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) at 24 hours before remifentanil infusion and 4, 8, 24, and 48 hours after infusion. The expression levels of DRP1 and NR2B were measured after behavioral testing using Western blotting. In addition, DRP1 expression was knocked down by intrathecal administration of AS-DRP1 to investigate the effects of DRP1 on RIH. The behavioral testing, the expression levels of spinal DRP1 and NR2B, and dorsal mitochondrial superoxide were measured. Changes in mitochondrial morphology were assessed using electron microscopy. Results: After remifentanil exposure, upregulation of spinal DRP1 and NR2B was observed along with a reduction in PWMT and PWTL. In addition, AS-DRP1 improved RIH-induced PWTL and PWMT (P < 0.001 and P < 0.001) and reduced remifentanil-mediated enhancement of spinal DRP1 and NR2B expression (P = 0.020 and P = 0.022). More importantly, AS-DRP1 reversed RIH-induced mitochondrial fission (P = 0.020) and mitochondrial superoxide upregulation (P = 0.031). Conclusions: These results indicate that AS-DRP1 could modulate NMDA receptor expression to prevent RIH through the DRP1-mitochondria-ROS pathway.

Key Genes Associated With Non-Alcoholic Fatty Liver Disease and Polycystic Ovary Syndrome.

Background: Polycystic ovary syndrome (PCOS) is the most common metabolic and endocrinopathies disorder in women of reproductive age and non-alcoholic fatty liver (NAFLD) is one of the most common liver diseases worldwide. Previous research has indicated potential associations between PCOS and NAFLD, but the underlying pathophysiology is still not clear. The present study aims to identify the differentially expressed genes (DEGs) between PCOS and NAFLD through the bioinformatics method, and explore the associated molecular mechanisms. Methods: The microarray datasets GSE34526 and GSE63067 were downloaded from Gene Expression Omnibus (GEO) database and analyzed to obtain the DEGs between PCOS and NAFLD with the GEO2R online tool. Next, the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis for the DEGs were performed. Then, the protein-protein interaction (PPI) network was constructed and the hub genes were identified using the STRING database and Cytoscape software. Finally, NetworkAnalyst was used to construct the network between the targeted microRNAs (miRNAs) and the hub genes. Results: A total of 52 genes were identified as DEGs in the above two datasets. GO and KEGG enrichment analysis indicated that DEGs are mostly enriched in immunity and inflammation related pathways. In addition, nine hub genes, including TREM1, S100A9, FPR1, NCF2, FCER1G, CCR1, S100A12, MMP9, and IL1RN were selected from the PPI network by using the cytoHubba and MCODE plug-in. Then, four miRNAs, including miR-20a-5p, miR-129-2-3p, miR-124-3p, and miR-101-3p, were predicted as possibly the key miRNAs through the miRNA-gene network construction. Conclusion: In summary, we firstly constructed a miRNA-gene regulatory network depicting interactions between the predicted miRNA and the hub genes in NAFLD and PCOS, which provides novel insights into the identification of potential biomarkers and valuable therapeutic leads for PCOS and NAFLD.

Isoflurane and Sevoflurane Induce Cognitive Impairment in Neonatal Rats by Inhibiting Neural Stem Cell Development Through Microglial Activation, Neuroinflammation, and Suppression of VEGFR2 Signaling Pathway.

Inhaled anesthetics are known to induce neurotoxicity in the developing brains of rodents, although the mechanisms are not well understood. The aim of this study was to elucidate the molecular mechanisms underlying anesthetics-induced neurodevelopmental toxicity by VEGF receptor 2 (VEGFR2) through the interaction between microglia and neural stem cells (NSCs) in postnatal day 7 (P7) rats. Cognitive function of P7 rats exposed to isoflurane and sevoflurane were assessed using Morris Water Maze and T maze tests. We also evaluated the expression levels of NSC biomarkers (Nestin and Sox2), microglia biomarker (CD11b or or IBA1), pro-inflammatory cytokines (IL-6 and TNF-α), and VEGFR2 using western blotting and immunohistochemistry in the brains of control and anesthesia-treated rats. We found spatial learning and working memory was impaired 2 weeks after anesthetics exposure in rats. Isoflurane induced stronger and more prolonged neurotoxicity than sevoflurane. However, cognitive functions were recovered 6 weeks after anesthesia. Isoflurane and sevoflurane decreased the levels of Nestin, Sox2, and p-VEGFR2, activated microglia, decreased the number of NSCs and reduced neurogenesis and the proliferation of NSCs, and increased the levels of IL-6, TNF-α, and CD11b. Our results suggested that isoflurane and sevoflurane induced cognitive impairment in rats by inhibiting NSC development and neurogenesis via microglial activation, neuroinflammation, and suppression of VEGFR2 signaling pathway.

Wnt3a Inhibitor Attenuates Remifentanil-Induced Hyperalgesia via Downregulating Spinal NMDA Receptor in Rats.

PURPOSE: The upregulation of spinal NMDA receptor is a crucial mechanism in remifentanil-induced hyperalgesia (RIH). Wnt3a/ß-catenin pathway plays an important role in neuropathic pain. We hypothesized that wnt3a inhibitor (iwp-2) could downregulate the expression of NR2B subunit in NMDA receptor, in order to relieve RIH. MATERIALS AND METHODS: The study has 2 phases. The phase 1 study is designed by different doses of iwp-2 groups to create an appropriate iwp-2 dose used in RIH alleviation. The phase 2 study is designed to prove that the wnt3a inhibitor could downregulate the activation of the NR2B to inhibit RIH in rats. Thermal hyperalgesia (PWTL) and mechanical allodynia (PWMT) were evaluated after RIH. The area under the PWTL and PWMT curves (AUC) were calculated. The amount of activated NR2B subunit, c-fos, NF-κB, ß-catenin, wnt3a and p-GSK-3ß (Ser9) were detected in the lumbar spinal cord. RESULTS: Remifentanil infusion could induce overexpression of ß-catenin and wnt3a in rats. Iwp-2 (60µM, 120µM, 180µM) could dose-dependently inhibit thermal hyperalgesia and mechanical allodynia in rats. In phase 2 study, both NR2B subunit antagonist Ro25-6981 and iwp-2 decreased the amount of activated NR2B, enhanced p-GSK-3ß (Ser9), reduced ß-catenin, c-fos and NF-κB in the lumbar spinal cord (p < 0.001). In comparison with the group iwp-2, the group of Ro25-6981 had more benefit in reversing hyperalgesia, including higher AUC value of PWTL (p = 0.022) and PWMT (p = 0.035). CONCLUSION: Remifentanil exposure could induce overexpression of wnt3a and enhance the production of ß-catenin in the spinal dorsal horn. Inhibition of wnt3a response was capable of attenuating RIH in alleviating hyperalgesia-related behavioral parameters, as well as reducing overexpression of c-fos, NF-κB, NR2B in spinal dorsal horn.

Isoflurane anesthesia in aged mice and effects of A1 adenosine receptors on cognitive impairment.

AIMS: Isoflurane may not only accelerate the process of Alzheimer's disease (AD), but increase the risk of incidence of postoperative cognitive dysfunction (POCD). However, the underlying mechanisms remain unknown. This study was designed to investigate whether isoflurane contributed to the POCD occurrence through A1 adenosine receptor (A1AR) in aged mice. METHODS: We assessed cognitive function of mice with Morris water maze (MWM) and then measured expression level of two AD biomarkers (P-tau and Aß) and a subtype of the NMDA receptor (NR2B) in aged wild-type (WT) and homozygous A1 adenosine receptor (A1AR) knockout (KO) mice at baseline and after they were exposed to isoflurane (1.4% for 2 hours). RESULTS: For cognitive test, WT mice with isoflurane exposure performed worse than the WT mice without isoflurane exposure. However, A1AR KO mice with isoflurane exposure performed better than WT mice with isoflurane exposure. WT mice exposed to isoflurane had increased levels of Aß and phosphorylated tau (P-tau). Levels of Aß and P-tau were decreased in A1AR KO mice, whereas no differences were noted between KO mice with and without isoflurane exposure. NR2B expression was inversely related to that of P-tau, with no differences found between KO mice with and without isoflurane exposure. CONCLUSIONS: We found an association between isoflurane exposure, impairment of spatial memory, decreasing level of NR2B, and increasing levels of A-beta and P-tau, presumably via the activation of the A1A receptor.