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Lasing in optimized two-dimensional iron-nail-shaped rod photonic crystals
摘要： We demonstrated lasing at the Γ-point band-edge (BE) modes in optimized two-dimensional iron-nail-shaped rod photonic crystals by optical pulse pumping at room temperature. As the radius of the rod increased quadratically toward the edge of the pattern, the quality factor of the Γ-point BE mode increased up to three times, and the modal volume decreased to 56% compared with the values of the original Γ-point BE mode because of the reduction of the optical loss in the horizontal direction. Single-mode lasing from an optimized iron-nail-shaped rod array with an InGaAsP multiple quantum well embedded in the nail heads was observed at a low threshold pump power of 160 μW. Real-image-based numerical simulations showed that the lasing actions originated from the optimized Γ-point BE mode and agreed well with the measurement results, including the lasing polarization, wavelength, and near-field image.
关键词： optical pulse pumping,photonic crystals,iron-nail-shaped rod,lasing,band-edge modes
更新于2025-09-04 15:30:14
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Fe3O4/SiO2 Core Shell Nanostructures: Preparation and Characterization
摘要： Silica coated iron oxide nanoparticles with controlled silica shell thickness were prepared by a modified St?ber method. Modification of the St?ber method consisted of changing the synthesis conditions to control the thickness of the SiO2 shell. The core-shell nanoparticles were characterized by means of X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy and vibrational sample magnetometry. It was found that the shell formed after 8 hours of stirring. An increase of the tetraethoxysilane-magnetite mass ratio from 12.5 to 25.1 led to an increase of the shell thickness, whereas further increase in the tetraethoxysilane-magnetite mass ratio (from 25.1 to 37.6) led to decrease shell thickness. The core size has only insignificant influence on the shell thickness. Magnetic properties of composite particles correlate well with properties of pure magnetite nanoparticles considering dilution of magnetic particles by silica. Obtained results can be used for fabrication of silica shell with controlled thickness on the surface of different sized magnetite nanoparticles.
关键词： FTIR,iron oxide,surface functionalization,silica coated,nanoparticles
更新于2025-09-04 15:30:14
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Hydrogen Peroxide Responsive Iron-Based Nanoplatform for Multimodal Imaging-Guided Cancer Therapy
摘要： Cancer multimodal phototherapy triggered by hydrogen peroxide has attracted widespread attention as a dominating strategy to increase phototherapeutic efficiency. Herein, a hydrogen peroxide responsive iron oxide nanoplatform, with the diameter of about 50 nm, is fabricated to intracellularly trigger the Fenton reaction and achieve synergistic photodynamic therapy and photothermal therapy. The nanoplatform based on iron oxide nanoparticles is decorated with indocyanine green (ICG, photosensitizer) and hyaluronic acid (HA, targeting molecular) through electrostatic interaction, thus the as-prepared nanoplatform (IONPs-ICG-HA) exhibits excellent active targeting ability and biocompatibility. More importantly, it can effectively utilize the intratumoral overproduced hydrogen peroxide to generate reactive oxygen species for cancer cell killing via intracellular Fenton reactions. In vitro and in vivo experiments reveal that the IONPs-ICG-HA nanocomposites realize effective photoacoustic/photothermal/fluorescence imaging–guided phototherapy, leading to promising hydrogen peroxide responsive cancer theranostics.
关键词： multiple bioimaging,iron oxide,synergistic phototherapy,hydrogen peroxide
更新于2025-09-04 15:30:14
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Exploration of charge carrier delocalization in the iron oxide/CdS type-II heterojunction band alignment for enhanced solar-driven photocatalytic and antibacterial applications
摘要： Recyclable magnetic photocatalysts of iron oxide (IO)/CdS core/shell nanocrystals (CSNCs) were prepared by a facile sequential one-pot method using 3, 3'-thiobispropanoic acid (TDP) as a bridge. The CSNCs showed redshift in absorption edge, decrease in the optical band gap, reduced exciton decay rates and increment in particle size. Quenching studies have been employed to understand the position of the electron/hole wave-functions at the IO/CdS interface. Antimicrobial tests have also been performed using broth tube dilution and disc diffusion methods against S. aureus. Additionally, photocatalytic properties of IO/CdS CSNCs have been evaluated for the decomposition of xylenol blue. In comparison with CdS quantum dots (QDs) and iron oxide nanoparticles (IONPs), the IO/CdS CSNCs showed improved photocatalytic and bactericidal activities. Finally, levels of oxidative damage to proteins and lipids were evaluated.
关键词： Photocatalysis,Wave-function engineering,Advanced oxidation process,Iron oxide/CdS nanocrystals,Photocatalytic bacterial inactivation
更新于2025-09-04 15:30:14
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Laboratory precision measurements of optical emissions from coronal iron
摘要： Total solar eclipses, as the recent one seen across North America, are rare opportunities for optical spectroscopy of the corona. In view of the dearth of accurate rest-frame wavelength data, we measured 11 of the strongest optical coronal lines belonging to Fe X-XIV thereby proving the existence of the Fe XII line at 290.385(8) nm. Four lines, such as the green coronal line at 530.28113(13) nm, were measured with unprecedented precision, allowing in principle for absolute velocity determinations of plasmas with uncertainties of 0.08 km s?1. These results furthermore stringently benchmark the theory of complex open-3p-shell ions.
关键词： solar eclipses,coronal iron,optical emissions,spectroscopy,precision measurements
更新于2025-09-04 15:30:14
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On the Fluorescent, Steric and Electronic Factors Affecting the Detection of Metallic Ions Using an Imidazolyl-Phenolic Derived Fluorescent Probe
摘要： The imidazolyl-phenolic probe used at the present study has its photophysic properties regulated by a tautomeric equilibrium. After the absorption of a photon, an excited state intramolecular proton transfer process generates a ketonic species, responsible for the 440 nm emission (in CH3CN/H2O, 95:5, v/v). Addition of Cu2+, Al3+, Cr3+ and Fe3+ suppresses emission through a combination of dynamic and static-like quenching, as indicated by Stern-Volmer plots, with a higher sensitivity for Cu2+ (KSV = 1.90 × 105 and 2.40 × 104 L mol–1, respectively, for Cu2+ and Fe3+). The trivalent ions led to the formation of a locked-enol tautomer that emits at shorter wavelengths; this coordinated compound is also quenched at metallic ions concentrations above 20 μmol L–1, due to a collisional process. When compared to another imidazolyl-phenolic probe, experimental and simulated data revealed that fluorescent, steric and electronic effects regulate their sensitivity towards the ions.
关键词： iron(III),copper(II),fluorescent sensor,ESIPT,tautomerization
更新于2025-09-04 15:30:14