- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Nonlinear light generation in topological nanostructures
摘要： Topological photonics has emerged as a route to robust optical circuitry protected against disorder and now includes demonstrations such as topologically protected lasing and single-photon transport. Recently, nonlinear optical topological structures have attracted special theoretical interest, as they enable tuning of topological properties by a change in the light intensity and can break optical reciprocity to realize full topological protection. However, so far, non-reciprocal topological states have only been realized using magneto-optical materials and macroscopic set-ups with external magnets, which is not feasible for nanoscale integration. Here we report the observation of a third-harmonic signal from a topologically non-trivial zigzag array of dielectric nanoparticles and the demonstration of strong enhancement of the nonlinear photon generation at the edge states of the array. The signal enhancement is due to the interaction between the Mie resonances of silicon nanoparticles and the topological localization of the electric field at the edges. The system is also robust against various perturbations and structural defects. Moreover, we show that the interplay between topology, bi-anisotropy and nonlinearity makes parametric photon generation tunable and non-reciprocal. Our study brings nonlinear topological photonics concepts to the realm of nanoscience.
关键词： Silicon nanoparticles,Nonlinear light generation,Third-harmonic signal,Mie resonances,Topological nanostructures
更新于2025-09-09 09:28:46
-
Hybrid Nanomaterials of Conjugated Polymers and Albumin for Precise Photothermal Therapy
摘要： Heretofore, conjugated polymers (CPs) attract considerable attention in photothermal therapy (PTT). Although various CPs with different structures have been reported, the suboptimal circulation persistence and biodistribution limit their efficacy in tumor treatment. Human serum albumin (HSA), an endogenous plasm protein, has been widely functioned as a carrier for therapeutic agents. Herein, we construct nanocomplexs C16 pBDP@HSA NPs from hydrophobic 4, 4-difluoro-4-bora-3a, 4adiaza-s-indacene (BODIPY)-containing CPs and HSA, which exhibit robust stability in physiological conditions and excellent photothermal activity upon irradiation. The high photothermal conversion efficiency of 37.5 %, higher than that of other reported PTT agents such as gold nanorods, phosphorus quantum dots and 2D materials, results in the potent photocytotoxicity towards cancer cells. Simultaneously, C16 pBDP@HSA NPs’ capabilities of near infrared fluorescence and photoacoustic imaging can provide guidance to the PTT. The outstanding inhibition of tumor growth results from great photothermal activity, the benefited accumulation in tumor and optimal timing of treatment. To the best of our knowledge, this is the first study which combines the BODIPY-based CPs and HSA in one nanostructure and finds application in cancer treatment. Moreover, this article also offers a new strategy for other insoluble macromolecules to explore more biomedical applications.
关键词： photothermal therapy,albumin,hybrid nanoparticles,conjugated polymers,BODIPY
更新于2025-09-09 09:28:46
-
ZnO nanoparticles modified with an amphipathic peptide show improved photoprotection in skin
摘要： ZnO nanoparticles of different sizes were functionalized with an amphipathic peptide and its effect on nanoparticle stabilization and UV photoprotective activity was studied in this article. The peptide modified nanoparticles exhibited lower aggregation, significant reduction in Zn2+ leaching in-vitro and even inside the cells for smaller particle sizes, reduced photocatalytic activity and reduced cellular toxicity under UV-B treated conditions. In addition, the peptide modified 60 nm sized ZnO nanoparticles showed lower genotoxicity, lower oxidative stress induction levels, less DNA damage responses and less immunogenic potential than the bare counterparts in presence of UV-B rays. They localized more in the stratum corneum and epidermis ex-vivo indicating better retention in epidermis and demonstrated improved UV-B protection and/or skin integrity in SKH-1 mice in-vivo as compared to unmodified nanoparticles and commercial UV protective agents tested. To our knowledge, this is the first report on application of peptide modified ZnO nanoparticles for improved photoprotection.
关键词： UV-B rays,ZnO nanoparticles,cytotoxicity,cell penetrating peptide,photoprotection
更新于2025-09-09 09:28:46
-
Fabrication and analysis of the structural phase transition of ZrO <sub/>2</sub> nanoparticles using modified facile sol–gel route
摘要： The synthesis of zirconia nanoparticles is achieved through a modified facile sol–gel route. The as-prepared gel is analyzed thermally using TGA and DTA techniques to spot the crystallization process of zirconia nanoparticles. The prepared gel is then annealed at different temperatures and the structure was found to change between tetragonal and monoclinic crystal systems. The first stable tetragonal phase is achieved after annealing for 2 h at 400°C. The annealed powders between 600°C and 800°C demonstrate mixed tetragonal/monoclinic phases. Annealing at 1000°C and higher temperatures up to 1200°C resulted in pure monoclinic phase. Cubic phase was not detected within the annealing temperature range in this study. The elemental analysis of the annealed powder confirmed the formation of zirconia nanoparticles with the chemical formula ZrO2. The FTIR spectra of the annealed samples introduced a variation in the vibrational bands especially around the phase transition temperature. HR-TEM images reported the formation of nano-zirconia crystals with apparently large particle sizes. The optical energy gap of zirconia nanoparticles is investigated and determined.
关键词： ZrO2 nanoparticles,HR-TEM,sol–gel synthesis,EDAX,optical energy gap
更新于2025-09-09 09:28:46
-
Photocatalytic and Antibacterial Activities of Silver and Iron Doped Titania Nanoparticles in Solution and Polyaspartic Coatings
摘要： Visible region active photocatalytic coatings are of interest for antimicrobial activity in low light applications or those employing LED lights with limited UV content. This work examined Ag and Fe doped titania nanoparticles (nTiO2) with varying dopant ranges in polyaspartic polymer coatings for potential light and dark activity. First, the Ag and Fe doped nTiO2 were synthesized by sol-gel chemistry with varying dopant concentrations, then characterized with respect to their size and aggregate size distribution, crystallinity, and surface and band gap features. The photocatalytic activity was then tested with methylene blue (MB) under both AM1.5G and visible light. From both sample sets (Ag and Fe doped nTiO2), the best photo catalytically active sample materials were chosen for antibacterial tests with gram negative Escherichia coli (E. coli) and gram positive Bacillus subtilis (B. subtilis) in (a) solution and (b) polyaspartic nanocomposites under UV and visible irradiation. The results showed that Ag doped nTiO2 samples delivered the best photocatalytic activity and excellent antibacterial action, even in the dark, attributed to both an enhanced band gap and surface area, as well as a combination of photocatalytic activity and Ag being present at the nanoparticle’s (NP) surface. No leaching of Ag at room temperature was observed from the nTiO2 structure, giving potential for next generation coatings that are both light and dark active.
关键词： Fe doping,polyaspartic composites,antibacterial activity,photo-catalysis,Ag doping,nanoparticles,Titania
更新于2025-09-09 09:28:46
-
[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Polymer/Ag Nanoparticles Composite for Chloroform Detection
摘要： In this paper we report on changes in the extinction spectra of a nanocomposite consisting of Ag nanoparticles arranged into poly(glycidyl methacrylate) host matrix. Two collective surface plasmon modes denoted as P and T were identified in the spectrum. They associated with electric dipoles perpendicular and parallel to the plane of the array respectively. It was found experimentally that intensity and bandwidth of corresponding bands decrease when the nanocomposite is exposed to chloroform vapor. At the same time, both plasmon bands shift toward shorter wavelength. Those dependences can be explained by weakening of the electrodynamic coupling between LSPR in neighboring nanoparticles due to the increase of the distance between particles caused by swelling of the polymer matrix. The spectral changes are fully reversible. It was found that sensitivity of the nanocomposite sensor to chloroform vapor is 0.02 nm/ppm with the response time t=25 s.
关键词： composite,localized surface plasmon resonanse,silver nanoparticles,vapor sensor
更新于2025-09-09 09:28:46
-
ASAXS study of CaF <sub/>2</sub> nanoparticles embedded in a silicate glass matrix
摘要： The formation and growth of nanosized CaF2 crystallites by heat treatment of an oxyfluoride glass of composition 7.65Na2O–7.69K2O–10.58CaO–12.5CaF2–5.77Al2O3–55.8SiO2 (wt%) was investigated using anomalous small-angle X-ray scattering (ASAXS). A recently developed vacuum version of the hybrid pixel detector Pilatus 1M was used for the ASAXS measurements below the Ca K-edge of 4038 eV down to 3800 eV. ASAXS investigation allows the determination of structural parameters such as size and size distribution of nanoparticles and characterizes the spatial distribution of the resonant element, Ca. The method reveals quantitatively that the growing CaF2 crystallites are surrounded by a shell of lower electron density. This depletion shell of growing thickness hinders and finally limits the growth of CaF2 crystallites. Moreover, in samples that were annealed for 10 h and more, additional very small heterogeneities (1.6 nm diameter) were found.
关键词： silicate glass matrix,electron density,CaF2 nanoparticles,ASAXS,nanostructure
更新于2025-09-09 09:28:46
-
Deposition Time Dependent Properties of Copper Tin Telluride (Cu <sub/>2</sub> SnTe <sub/>3</sub> ) Nanoparticles for Solar Absorber Applications
摘要： We report the growth of copper tin telluride nanoparticles as an absorber layer using a chemical bath deposition (CBD) process for solar selective applications. The XRD results showed the phase of Cu2SnTe3 with a cubical structure. The larger-sized nanoparticles resulted with increased absorption properties and the optical band gap ranging from 1.93, 1.90, 1.58 and 1.56 eV for deposition times of 20–120 min, respectively. Then, the electrical properties of Cu2SnTe3 nanoparticles were also provided a higher current (～6–8 mA) with bias potential of zero.
关键词： Selective Solar Absorber,Nanoparticles,Copper Tin Telluride,Chemical Bath Deposition
更新于2025-09-09 09:28:46
-
Elusive Pure Anapole Excitation in Homogenous Spherical Nanoparticles with Radial Anisotropy
摘要： For homogenous isotropic dielectric nanospheres with incident plane waves, Cartesian electric and toroidal dipoles can be tunned to cancel each other in terms of far-field scattering, leading to the effective anapole excitation. At the same time however, other multipoles such as magnetic dipoles with comparable scattered power are simultaneously excited, mixing with the anapole and leading to a nonnegligible total scattering cross-section. Here, we show that, for homogenous dielectric nanospheres, radial anisotropy can be employed to significantly suppress the other multipole excitation, which at the same time does not compromise the property of complete scattering cancellation between Cartesian electric and toroidal dipoles. This enables an elusive pure anapole excitation within radially anisotropic dielectric nanospheres, which may shed new light on many scattering related fundamental researches and applications.
关键词： toroidal dipole,scattering,radial anisotropy,anapole,nanoparticles
更新于2025-09-09 09:28:46
-
Sonochemical syntheses of iron doped zinc oxide nanoparticles at different sonication powers and temperatures with their application for photocatalytic degradation of PVC-ZnO composite film
摘要： Doping with iron enhances various properties of zinc oxide making it suitable for several applications. Sonochemical route is an easy way for synthesis of doped ZnO nanoparticles. Input-powers of ultrasound and synthesis–temperature have significant influences over the characteristics of iron-doped zinc oxide nanoparticles. Effects of the varying sonication powers and synthesis temperatures on the average grain size, band gap and magnetic properties of doped ZnO were studied using UV-vis spectrophotometer, X-ray diffraction (XRD), field emission scanning electron micrography (FESEM) with Energy dispersive X-ray spectroscopy (EDX) and SQUID-magnetometer. Both temperature and sonication power influenced the characteristics. The nanoparticles were then used for casting composite films with polyvinyl chloride (PVC) and photodegradation of the film was examined under sunlight. Performances of nanoparticles synthesised at different conditions were compared. Maximum degradation of about 12% was obtained within three hours with nanoparticles synthesised at 42 W power and 30°C temperature.
关键词： sonication-power,temperature,Fe-doped zinc oxide,nanoparticles,photocatalyst,degradation,ultrasound,PVC-nanocomposite,bandgap,magnetization,characterisation
更新于2025-09-05 23:13:11