A facile green synthesis of gold nanoparticles using Canthium parviflorum extract sustainable and energy efficient photocatalytic degradation of organic pollutants for environmental remediation.

Organic dye and nitrophenol pollution from textiles and other industries present a substantial risk to people and aquatic life. One of the most essential remediation techniques is photocatalysis, which uses the strength of visible light to decolorize water. The present study reports Canthium Parviflorum (CNP) leaf extract utilization as an effective bio-reductant for green synthesis of Au NPs. A simple, eco-friendly process with low reaction time and temperature was adopted to synthesize CNP extract-mediated Au-NPs (CNP-AuNPs). The prepared AuNPs characterization involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS) surface area analysis, ultraviolet-visible spectroscopy (UV-Vis). XRD results showed that the cubic-structured AuNPs had a crystallite size of 14.12 nm. Assessment of organic dyes performance in degrading brilliant green (BTG) and amido black 10B (AMB) under visible light irradiation highlights an impressive 83.25% and 86% degradation efficiency within 120 min, accompanied by a kinetic rate constant dyes was found to be 0.0828 min⁻1, BTG, and 0.0123 min⁻1, Furthermore, the reduction of 4-nitrophenol by NaBH4 using CNP-AuNPs as a catalyst demonstrated good catalytic performance and rapid degradation at 89.4%. and rate constant 0.099 min-1 followed pseudo-first-order. The LC-MS analysis identified various intermediates during the degradation of the CR dye. Radical trapping experiments suggest that photogenerated free electrons and hydroxyl radicals are crucial for degrading the amido black 10B dye The AuNPs influenced the significant factors responsible for the photocatalytic activity, such as the increase in range of absorbance, increased e- and h+ pair separation, improvement in the charge transfer process, and active site formation, which significantly enhanced the process of degradation. We found that the CNP-AuNPs could effectively remove dyes and nitrophenol from industrial wastewater.

Polarization-sensitive tunable extraordinary terahertz transmission based on a hybrid metal-vanadium dioxide metasurface.

Thermally tunable extraordinary terahertz transmission in a hybrid metal-vanadium dioxide (VO2) metasurface is numerically demonstrated. The metasurface consists of a metal sheet perforated by square loops, while the loops are connected with strips of VO2. The frequency and amplitude of the transmission resonance are modulated by controlling the conductivity of VO2. For a y-polarized incident field, the resonance transmission peak redshifts from 0.88 to 0.81 THz upon insulator-to-metallic phase transition of VO2. For an x-polarized incident field, the transmission resonance at 0.81 THz is observed in the insulator phase. However, in the metallic phase of VO2, the electromagnetic field is effectively reflected in the 0.5-1.1 THz range with a transmission level lower than 0.14. The proposed metasurface can be utilized as a terahertz modulator, reconfigurable filter, or switch.

Hybrid plasmonic slot waveguide with a metallic grating for on-chip biosensing applications.

Designing reliable and compact integrated biosensors with high sensitivity is crucial for lab-on-a-chip applications. We present a bandpass optical filter, as a label-free biosensor, based on a hybrid slot waveguide on the silicon-on-insulator platform. The designed hybrid waveguide consists of a narrow silicon strip, a gap, and a metallic Bragg grating with a phase-shifted cavity. The hybrid waveguide is coupled to a conventional silicon strip waveguide with a taper. The effect of geometrical parameters on the performance of the filter is investigated by 3D finite-difference time-domain simulations. The proposed hybrid waveguide has potential for sensing applications since the optical field is pulled into the gap and outside of the silicon core, thus increasing the modal overlap with the sensing region. This biosensor offers a sensitivity of 270 nm/RIU, while it only occupies a compact footprint of 1.03µm×17.6µm.

Exciton Dipole-Dipole Interaction in a Single Coupled-Quantum-Dot Structure via Polarized Excitation.

We find that the exciton dipole-dipole interaction in a single laterally coupled GaAs/AlGaAs quantum dot structure can be controlled by the linear polarization of a nonresonant optical excitation. When the excitation intensity is increased with the linearly polarized light parallel to the lateral coupling direction [11̅0], excitons (X1 and X2) and local biexcitons (X1X1 and X2X2) of the two separate quantum dots (QD1 and QD2) show a redshift along with coupled biexcitons (X1X2), while neither coupled biexcitons nor a redshift are observed when the polarization of the exciting beam is perpendicular to the coupling direction. The polarization dependence and the redshift are attributed to an optical nonlinearity in the exciton Förster resonant energy transfer interaction, whereby exciton population transfer between the two quantum dots also becomes significant with increasing excitation intensity. We have further distinguished coupled biexcitons from local biexcitons by their large diamagnetic coefficient.

Highly Conductive PEDOT:PSS Films with 1,3-Dimethyl-2-Imidazolidinone as Transparent Electrodes for Organic Light-Emitting Diodes.

Highly conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PEDOT: PSS) films as transparent electrodes for organic light-emitting diodes (OLEDs) are doped with a new solvent 1,3-dimethyl-2-imidazolidinone (DMI) and are optimized using solvent post-treatment. The DMI doped PEDOT: PSS films show significantly enhanced conductivities up to 812.1 S cm(-1) . The sheet resistance of the PEDOT: PSS films doped with DMI is further reduced by various solvent post-treatment. The effect of solvent post-treatment on DMI doped PEDOT: PSS films is investigated and is shown to reduce insulating PSS in the conductive films. The solvent posttreated PEDOT: PSS films are successfully employed as transparent electrodes in white OLEDs. It is shown that the efficiency of OLEDs with the optimized DMI doped PEDOT: PSS films is higher than that of reference OLEDs doped with a conventional solvent (ethylene glycol). The results present that the optimized PEDOT: PSS films with the new solvent of DMI can be a promising transparent electrode for low-cost, efficient ITO-free white OLEDs.

Synthesis and Characterization of Multiwalled Carbon Nanotubes/Poly(HEMA-co-MMA) by Utilizing Click Chemistry.

The hybrid material consisting of multi walled carbon nanotubes (MWNTs) and poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) [poly(HEMA-co-MMA)] was synthesized by a combination of RAFT and Click chemistry. In the primary stage, the copolymer poly(HEMA-co-MMA) was prepared by applying RAFT technique. Alkynyl side groups were incorporated onto the poly(HEMA-co-MMA) backbone by esterification reaction. Then, MWNTs-N3 was prepared by treating MWNTs with 4-azidobutylamine. The click coupling reaction between azide-functionalized MWNTs (MWNTs-N3) and the alkyne-functionalized random copolymer ((HEMA-co-MMA)-Alkyne) with the Cu(I)-catalyzed [3+2] Huisgen cycloaddition afforded the hybrid compound. The structure and properties of poly(MMA-co-HEMA)-g-MWNTs were investigated by FT-IR, EDX and TGA measurements. The copolymer brushes were observed to be immobilized onto the functionalized MWNTs by SEM and TEM analysis.

Prenylated Flavonoids from Cudrania tricuspidata Suppress Lipopolysaccharide-Induced Neuroinflammatory Activities in BV2 Microglial Cells.

In Korea and China, Cudrania tricuspidata Bureau (Moraceae) is an important traditional medicinal plant used to treat lumbago, hemoptysis, and contusions. The C. tricuspidata methanol extract suppressed both production of NO and PGE2 in BV2 microglial cells. Cudraflavanone D (1), isolated from this extract, remarkably suppressed the protein expression of inducible NO synthase and cyclooxygenase-2, and decreased the levels of NO and PGE2 in BV2 microglial cells exposed to lipopolysaccharide. Cudraflavanone D (1) also decreased IL-6, TNF-α, IL-12, and IL-1ß production, blocked nuclear translocation of NF-κB heterodimers (p50 and p65) by interrupting the degradation and phosphorylation of inhibitor of IκB-α, and inhibited NF-κB binding. In addition, cudraflavanone D (1) suppressed the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK pathways. This study indicated that cudraflavanone D (1) can be a potential drug candidate for the cure of neuroinflammation.

Preparation of ß-Cyclodextrin Multi-Decorated Halloysite Nanotubes as a Catalyst and Nanoadsorbent for Dye Removal.

Hybrid materials of ß-cyclodextrin multi-decorated halloysite nanotubes (HNTs-g-ßCD) were prepared by a facile route, which showed high efficiency for catalysis and dye adsorption. Initially, the surface of halloysite nanotubes (HNTs) was modified with poly(glycidyl methacrylate) by the reversible addition fragmentation chain transfer (RAFT) polymerization of glycidyl methacrylate having epoxy groups as a monomer. Subsequently, ß-cyclodextrin was conjugated with the modified HNTs to produce HNTs-g-ßCD by the epoxide ring-opening reaction of mono-6-deoxy-6-hexanediamine-ß-cyclodextrin. The nanocomposites were characterized by FT-IR, TGA, SEM, and TEM. The HNTs-g-ßCD composites could be used as a nano adsorbent for methylene blue and a catalyst in the oxidation reaction of benzyl alcohol owing to the unique structure of ß-cyclodextrin. The HNTs-g-ßCD shows promiseas potential multi-functional materials by a combination of ß-cyclodextrin and HNTs properties.

Effect of Co doping concentration on structural properties and optical parameters of Co-doped ZnO thin films by sol-gel dip-coating method.

The structural and optical properties of Co-doped ZnO thin films prepared by a sol-gel dip-coating method were investigated. X-ray diffraction analysis showed that the thin films were grown with a c-axis preferred orientation. The position of the (002) peak was almost the same in all samples, irrespective of the Co concentration. It is thus clear that Co doping had little effect on the position of the (002) peak. To confirm that Co2+ was substituted for Zn2+ in the wurtzite structure, optical measurements were conducted at room temperature by a UV-visible spectrometer. Three absorption peaks are apparent in the Co-doped ZnO thin films that do not appear for the undoped ZnO thin film. As the Co concentration was increased, absorption related to characteristic Co2+ transitions increased because three absorption band intensities and the area underneath the absorption wells between 500 and 700 nm increased with increasing Co concentration. The optical band gap and static dielectric constant decreased and the Urbach energy and extinction coefficient increased with increasing Co concentration.

Influence of Sn doping on structural and optical properties of zinc oxide nanorods prepared via hydrothermal process.

Hydrothermally grown ZnO nanorods were doped with various concentrations of Sn, ranging from 0 to 2.5 at%. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), ultraviolet (UV)-visible spectroscopy, and Photoluminescence (PL) measurements were used to determine the effect of Sn doping on the structural and optical properties. In the SEM images, the nanorods have hexagonal wurtzite structure and the diameter of the nanorods increases with an increase in the Sn content. The optical parameters of the Sn-doped ZnO (SZO) nanorods such as the absorption coefficients, optical bandgaps, Urbach energies, refractive indices, dispersion parameters, dielectric constants, and optical conductivities were determined from the transmittance and reflectance results. In the PL spectra, the intensity of the NBE peak in the UV region decreases and is blue-shifted with an increase in the Sn content, while the DLE peaks of the nanorods in the visible region shift toward the low-energy region with the introduction of Sn.

Prognosis of amyotrophic lateral sclerosis patients after tracheostomy invasive ventilation in Korea.

Background: Tracheostomy invasive ventilation (TIV) is applied to a subset of amyotrophic lateral sclerosis (ALS) patients; however, its frequency and impact on prognosis vary across countries. Methods: We conducted a nationwide retrospective cohort study using Korean National Health Insurance claims data. All patients diagnosed with sporadic ALS from 2012 to 2017 were included, with the observation period until 2020. The survival time between the TIV and non-TIV groups was compared using propensity score matching analysis, and prognostic factors were assessed within the TIV group. Results: This study included 3484 ALS patients (mean [standard deviation] age, 62.4 [11.9] years, 60.4% male), among whom 1230 (35.3%) underwent TIV. After 1:1 propensity score matching, the survival duration between the two groups was not significantly different (28 vs. 25 months, p = 0.057). Cox regression indicated that older age (hazard ratios [HRs] for each decade compared to <40 years: 3.89, 3.83, 5.30, 6.78, and 8.40 [≥80 years]; p < 0.005 for all) and lower income (HR, 1.28; 95% confidence interval [CI], 1.09-1.52; p = 0.003) negatively impacted survival, while gastrostomy (HR, 0.57; 95% CI, 0.50-0.66; p < 0.001) and supportive care services (HR, 0.43; 95% CI, 0.32-0.59; p < 0.001) were associated with prolonged survival. Conclusions: TIV was administered to more than one-third of Korean ALS patients without significant survival prolongation. Older age, lower income, lack of gastrostomy, and insufficient supportive care were independent poor prognostic factors for survival, underscoring the importance of comprehensive management for ALS patients.

Improving infra-red polarized imaging efficiency in a bilayer wire-grid polarizer.

The optical, plasmonic, and imaging performance of an infra-red polarized system exceeds that of a conventional infra-red detector due to its high resolution and precision. The wire-grid polarizer has large potential for use in an infra-red polarized imaging device owing to its large polarization efficiency. In this study, we theoretically and experimentally investigate a method to improve the polarization efficiency of a wire-grid polarizer. Here, we demonstrated a high-performance wire grid polarizer with a maximum extinction ratio (ER) of 355 using a bilayer structure and dielectric material in the mid-wavelength infra-red (MWIR) region (3000 nm-5000 nm), which is a 4 times higher ER value than that of the monolayer structure. More interestingly, we were able to improve the performance of the bilayer wire-grid polarizer by devising a method to improve the surface roughness using Ar ion milling. The ER for the after-milled sample was 1255, which was markedly larger than that of the before-milled sample. The results of transmittance measurement confirmed that the improvement in the ER was due to the Fabry-Perot (F-P) phenomenon caused by constructive or destructive interference in the bilayer wire-grid structure and the enhancement of the surface smoothness. These results will help design a polarizer structure that will maximize the polarization efficiency and realize a high-performance infrared polarized imaging system.

Temperature dependence of indigo light emission from mesoporous ZnO/porous silicon nanocomposites.

Nanocomposites of mesoporous zinc oxide (ZnO) and porous silicon (PS) were prepared through a hydrothermal method. Room-temperature (RT) and temperature-dependent photoluminescence (PL) were performed to investigate the optical properties and temperature dependence of the indigo emission peak from the ZnO/PS nanocomposites. An indigo emission peak from the nanocomposites and a red emission peak from the PS were observed in the case of the mesoporous ZnO/PS nanocomposites. At 10 K, the nanocomposites exhibited four emission peaks at 3.108, 2.929, 2.730, and 2.248 eV, which correspond to the DX, AX, DX-1LO, and DX-2LO phonon replicas, respectively. With an increase in temperature from 10 to 275 K, the curves in the intensities of the emission peaks formed an inverted "S" shape while their energies remained nearly constant. At 300 K, however, only the AX emission peak was observed; the DX and LO phonon replicas disappeared. The intensities of the DX and AX emission peaks exhibited anomalous behaviors.

Magnesium content ratio effects of MgxZn1-xO seed layers on structural and optical properties of ZnO nanorods.

ZnO nanorods were grown on MgxZn1-xO seed layers with different content ratio ranging from 0 to 0.3 by hydrothermal method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out to investigate the effects of Mg content ratio for the MgxZn1-xO seed layers on the structural and optical properties of the ZnO nanorods. The surface morphology and structural properties of the MgxZn1-xO seed layers were changed by the Mg incorporation. However, the appearance, such as density, diameter, and shape, of the ZnO nanorods grown on the MgxZn1-xO seed layers was not changed significantly. The highest intensity ratio of the near-band-edge emission (NBE) to deep-level emission (DLE) and the narrowest full width at half maximum (FWHM) of the NBE peaks, indicating improvement in the crystallinity and luminescent properties of the ZnO crystals, were observed in the ZnO nanorods grown on the MgxZn1_xO seed layers with the content ratio of the 0.05.

Temperature-Dependent Exciton Dynamics in a Single GaAs Quantum Ring and a Quantum Dot.

Micro-photoluminescence was observed while increasing the excitation power in a single GaAs quantum ring (QR) at 4 K. Fine structures at the energy levels of the ground (N = 1) and excited (N = 2) state excitons exhibited a blue shift when excitation power increased. The excited state exciton had a strong polarization dependence that stemmed from the asymmetric localized state. According to temperature-dependence measurements, strong exciton-phonon interaction (48 meV) was observed from an excited exciton state in comparison with the weak exciton-phonon interaction (27 meV) from the ground exciton state, resulting from enhanced confinement in the excited exciton state. In addition, higher activation energy (by 20 meV) was observed for the confined electrons in a single GaAs QR, where the confinement effect was enhanced by the asymmetric ring structure.

Exfoliation of MoS2 Quantum Dots: Recent Progress and Challenges.

Although, quantum dots (QDs) of two-dimensional (2D) molybdenum disulfide (MoS2) have shown great potential for various applications, such as sensing, catalysis, energy storage, and electronics. However, the lack of a simple, scalable, and inexpensive fabrication method for QDs is still a challenge. To overcome this challenge, a lot of attention has been given to the fabrication of QDs, and several fabrication strategies have been established. These exfoliation processes are mainly divided into two categories, the 'top-down' and 'bottom-up' methods. In this review, we have discussed different top-down exfoliation methods used for the fabrication of MoS2 QDs and the advantages and limitations of these methods. A detailed description of the various properties of QDs is also presented.

Effects of precursor concentrations and thermal annealing on ZnO nanorods grown by hydrothermal method.

ZnO nanorods were grown on spin-coated ZnO seed layers by hydrothermal method. The ZnO nanorods were grown with various precursor concentrations ranging from 0.01 to 0.3 M. Field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out to investigate the structural and optical properties of the ZnO nanorods. The average diameter and length of the ZnO nanorods is increased as the precursor concentration increased from 0.01 to 0.3 M. From XRD, the intensity of ZnO (002) peak is increased and full width at half maximum (FWHM) of ZnO (002) decreased as the precursor concentration increased. The FWHM of near-band-edge emission (NBE) decreased and intensity ratio of the NBE to the deep-level emission (DLE) increased as the precursor concentration increased which indicated the optical property is improved. The DLE is red-shifted from yellow- to red-emission and its intensity is increased as the annealing temperature increased due to thermal diffusion process.

Ictal Swearing as a Lateralizing Value for the Dominant Hemisphere in Temporal Lobe Epilepsy.

Ictal swearing, as an epileptic manifestation, has rarely been reported. Despite its poor localization value and unclear mechanism, several previous studies have reported that it frequently originates from the temporal lobe and more often from the non-dominant hemisphere. Herein, we report a case of a 41-year-old right-handed man with a history of stereotypical manifestation of ictal swearing with a left (dominant) hemisphere origin, confirmed by video electroencephalography monitoring. Reasonable suspicion that repetitive swearing could be a manifestation of seizures is important for clinicians not to misdiagnose the disease.

Optical characteristics of type-II hexagonal-shaped GaSb quantum dots on GaAs synthesized using nanowire self-growth mechanism from Ga metal droplet.

We report the growth mechanism and optical characteristics of type-II band-aligned GaSb quantum dots (QDs) grown on GaAs using a droplet epitaxy-driven nanowire formation mechanism with molecular beam epitaxy. Using transmission electron microscopy and scanning electron microscopy images, we confirmed that the QDs, which comprised zinc-blende crystal structures with hexagonal shapes, were successfully grown through the formation of a nanowire from a Ga droplet, with reduced strain between GaAs and GaSb. Photoluminescence (PL) peaks of GaSb capped by a GaAs layer were observed at 1.11 eV, 1.26 eV, and 1.47 eV, assigned to the QDs, a wetting-like layer (WLL), and bulk GaAs, respectively, at the measurement temperature of 14 K and excitation laser power of 30 mW. The integrated PL intensity of the QDs was significantly stronger than that of the WLL, which indicated well-grown GaSb QDs on GaAs and the generation of an interlayer exciton, as shown in the power- and temperature-dependent PL spectra, respectively. In addition, time-resolved PL data showed that the GaSb QD and GaAs layers formed a self-aligned type-II band alignment; the temperature-dependent PL data exhibited a high equivalent internal quantum efficiency of 15 ± 0.2%.

Comparative Chemico-Physical Analyses of Strain-Free GaAs/Al0.3Ga0.7As Quantum Dots Grown by Droplet Epitaxy.

We investigate the quantum confinement effects on excitons in several types of strain-free GaAs/Al 0 . 3 Ga 0 . 7 As droplet epitaxy (DE) quantum dots (QDs). By performing comparative analyses of energy-dispersive X-ray spectroscopy with the aid of a three-dimensional (3D) envelope-function model, we elucidate the individual quantum confinement characteristics of the QD band structures with respect to their composition profiles and the asymmetries of their geometrical shapes. By precisely controlling the exciton oscillator strength in strain-free QDs, we envisage the possibility of tailoring light-matter interactions to implement fully integrated quantum photonics based on QD single-photon sources (SPSs).