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- 实验方案
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Direct Observation of Curved Surface Enhanced Disordering in Ag <sub/>2</sub> S Nanoparticles
摘要： Surface induced order-disorder phase transition has been widely studied on flat bulk surfaces, while such a transition is poorly understood on curved surfaces in nanoscale. Here, we report a direct observation of the dynamic behaviors of surface-initiated disordering in Ag2S nanoparticles using atomic resolution in-situ transmission electron microscopy. It was found that the disordering behavior is different from the traditional model that the disordered layer follows a logarithmical thickness dependence with temperature. In particular, the disordering is largely enhanced at higher temperature when the radius of the residual order phase is getting smaller. Moreover, the correlation length of disordered phase was found to be several times larger than the typical value for bulk surfaces. This significantly enhanced disordering in nanoparticles could be attributed to the extra driving force provided by the decreasing of order-disorder interface area.
关键词： nanoscale,Ag2S nanoparticles,in-situ TEM,phase transition,surface-initiated disordering
更新于2025-09-04 15:30:14
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One Step Nanoscale Patterning of Silver Nanowire-Nitride Heterostructures using Substrate-Assisted Chemical Etching
摘要： Nanoscale etching and patterning of noble metals such as copper, silver and gold is extremely difficult to achieve due to the low volatility of group 11 metal compounds. Here, we introduce a method of nanoscale chemical etching that utilizes reactions between H2O adsorbates and N radicals generated from electron beam-induced etching (EBIE) of a h-BN or AlN substrate to achieve efficient and highly localized chemical etching of Ag nanowires and the underlying substrate. The volatilization of noble metal nanowires by radical species generated during EBIE of the underlying substrate represents a new class of EBIE reactions, which we term ‘substrate-assisted chemical etching’.
关键词： nanoscale etching,substrate-assisted chemical etching,electron beam-induced etching,silver nanowires,noble metals
更新于2025-09-04 15:30:14
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Facile and Efficient Welding of Silver Nanowires Based on UVA‐Induced Nanoscale Photothermal Process for Roll‐to‐Roll Manufacturing of High‐Performance Transparent Conducting Films
摘要： The continuous, large-area solution-processed production of silver nanowire (AgNW) transparent conducting films with outstanding optoelectronic and mechanical performance remains a challenge. Here, efficient welding of AgNWs is demonstrated using ultraviolet A (UVA) with the specific wavelength range from ≈320 to ≈400 nm based on a nanoscale photothermal process. The AgNW welding shows a self-terminating and self-limiting nature, and sensitivity to diameter of AgNWs. Sheet resistance of the UVA-illuminated (UVAI) AgNW films rapidly drops within 2 min without loss of transmittance. For the UVAI AgNW (30 nm in diameter) film, decrement of sheet resistance approaches three orders of magnitude (≈105–102 Ohm sq?1) with original transmittance being (97%) retained, which significantly enhances its optoelectronic properties. Enhanced mechanical flexibility, electromagnetic interference (EMI) shielding effectiveness (SE), and heating performance are obtained in the UVAI AgNW films. The SE and plateau temperature of the AgNW film increase to 25 dB and 50 °C after illumination, respectively. Smart window, transparent heater, and triboelectric nanogenerator based on the UVAI AgNW film demonstrate its versatile applications in optoelectronics. Finally, the welding method is easily integrated into a roll-to-roll process to manufacture AgNW film with a low sheet resistance of 25 Ohm sq?1 and a high transmittance of 90%, and excellent flexibility.
关键词： transparent conducting films,roll-to-roll process,nanoscale photothermal process,welding,silver nanowires
更新于2025-09-04 15:30:14
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - THz Near- Field Imaging and Spectroscopy with Nanoscale Resolution
摘要： Scattering-type near-field microscopy can overcome the limits in spatial resolution present in conventional THz imaging and spectroscopy techniques. This talk shows how THz near-field imaging and THz-TDS with a spatial resolution <20 nm can be realized with our neaSNOM microscope and some of the possible applications.
关键词： THz-TDS,nanoscale resolution,neaSNOM microscope,THz near-field imaging
更新于2025-09-04 15:30:14
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Internal strain tunes electronic correlations on the nanoscale
摘要： In conventional metals, charge carriers basically move freely. In correlated electron materials, however, the electrons may become localized because of strong Coulomb interactions, resulting in an insulating state. Despite considerable progress in the last decades, elucidating the driving mechanisms that suppress metallic charge transport, the spatial evolution of this phase transition remains poorly understood on a microscopic scale. Here, we use cryogenic scanning near-field optical microscopy to study the metal-to-insulator transition in an electronically driven charge-ordered system with a 20-nm spatial resolution. In contrast to common mean-field considerations, we observe pronounced phase segregation with a sharp boundary between metallic and insulating regions evidencing its first-order nature. Considerable strain in the crystal spatially modulates the effective electronic correlations within a few micrometers, leading to an extended “zebra” pattern of metallic and insulating stripes. We can directly monitor the spatial strain distribution via a gradual enhancement of the optical conductivity as the energy gap is depressed. Our observations shed new light on previous analyses of correlation-driven metal-insulator transitions.
关键词： nanoscale,electronic correlations,metal-insulator transition,condensed matter physics,strain
更新于2025-09-04 15:30:14
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Hybrid Nanomedicine Fabricated from Photosensitizer-Terminated Metal-Organic Framework Nanoparticles for Photodynamic Therapy and Hypoxia-Activated Cascade Chemotherapy
摘要： During photodynamic therapy (PDT), severe hypoxia often occurs as an undesirable limitation of PDT owing to the O2-consuming photodynamic process, compromising the effectiveness of PDT. To overcome this problem, several strategies aiming to improve tumor oxygenation are developed. Unlike these traditional approaches, an opposite method combining hypoxia-activated prodrug and PDT may provide a promising strategy for cancer synergistic therapy. In light of this, azido-/photosensitizer-terminated UiO-66 nanoscale metal–organic frameworks (UiO-66-H/N3 NMOFs) which serve as nanocarriers for the bioreductive prodrug banoxantrone (AQ4N) are engineered. Owing to the effective shielding of the nanoparticles, the stability of AQ4N is well preserved, highlighting the vital function of the nano-carriers. By virtue of strain-promoted azide–alkyne cycloaddition, the nanocarriers are further decorated with a dense PEG layer to enhance their dispersion in the physiological environment and improve their therapeutic performance. Both in vitro and in vivo studies reveal that the O2-depleting PDT process indeed aggravates intracellular/tumor hypoxia that activates the cytotoxicity of AQ4N through a cascade process, consequently achieving PDT-induced and hypoxia-activated synergistic therapy. Benefiting from the localized therapeutic effect of PDT and hypoxia-activated cytotoxicity of AQ4N, this hybrid nanomedicine exhibits enhanced therapeutic efficacy with negligible systemic toxicity, making it a promising candidate for cancer therapy.
关键词： hypoxia-activated prodrugs,cascade therapy,nanoscale metal–organic frameworks,banoxantrone,photodynamic therapy
更新于2025-09-04 15:30:14
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Additive-Manufacturing of 3D Glass-Ceramics down to Nanoscale Resolution
摘要： Fabrication of a true-3D inorganic ceramic with resolution down to nanoscale (～ 100 nm) using sol-gel resist precursor is demonstrated. The method has an unrestricted free-form capability, control of the ?ll-factor, and high fabrication throughput. A systematic study of the proposed approach based on ultrafast laser 3D lithography of organic-inorganic hybrid sol-gel resin followed by a heat treatment enabled formation of inorganic amorphous and crystalline composites guided by the composition of the initial resin. The achieved resolution of 100 nm was obtained for 3D patterns of complex free-form architectures. Fabrication throughput of 50 × 103 voxels/s is achieved; voxel - a single volume element recorded by a single pulse exposure. A post-exposure thermal treatment was used to form a ceramic phase which composition and structure were dependent on the temperature and duration of the heat treatment as revealed by Raman micro-spectroscopy. The X-ray diffraction (XRD) showed a gradual emergence of the crystalline phases at higher temperatures with a signature of cristobalite SiO2, a high-temperature polymorph. Also, a tetragonal ZrO2 phase known for its high fracture strength was observed. This 3D nano-sintering technique is scalable from nanoscale to millimeter dimensions and opens a conceptually novel route for optical 3D nano-printing of various crystalline inorganic materials de?ned by an initial composition for diverse applications for microdevices designed to function in harsh physical and chemical environments and at high temperatures.
关键词： ultrafast 3D laser nanolithography,3D nanoscale optical printing,inorganic 3D structures,high-temperature glass-ceramic materials,calcination
更新于2025-09-04 15:30:14
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Imaging the Local Charge Environment of Nitrogen-Vacancy Centers in Diamond
摘要： Characterizing the local internal environment surrounding solid-state spin defects is crucial to harnessing them as nanoscale sensors of external fields. This is especially germane to the case of defect ensembles which can exhibit a complex interplay between interactions, internal fields, and lattice strain. Working with the nitrogen-vacancy (NV) center in diamond, we demonstrate that local electric fields dominate the magnetic resonance behavior of NV ensembles at a low magnetic field. We introduce a simple microscopic model that quantitatively captures the observed spectra for samples with NV concentrations spanning more than two orders of magnitude. Motivated by this understanding, we propose and implement a novel method for the nanoscale localization of individual charges within the diamond lattice; our approach relies upon the fact that the charge induces a NV dark state which depends on the electric field orientation.
关键词： diamond,local electric fields,nanoscale localization,nitrogen-vacancy center,magnetic resonance
更新于2025-09-04 15:30:14
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Folic acid-nanoscale gadolinium-porphyrin metal-organic frameworks: fluorescence and magnetic resonance dual-modality imaging and photodynamic therapy in hepatocellular carcinoma
摘要： Background: Hepatocellular carcinoma (HCC) is the most common primary liver cancer and severely threatens human health. Since the prognosis of advanced HCC remains poor, there is an urgent need to develop new therapeutic approaches. Porphyrin metal-organic frameworks are a class of porous organic-inorganic hybrid functional materials with good biocompatibility. Methods: Gadolinium-porphyrin metal-organic frameworks were used as a skeleton for folic acid (FA) conjugation to synthesize a novel type of nanoparticle, denoted as folic acid-nanoscale gadolinium-porphyrin metal-organic frameworks (FA-NPMOFs). The FA-NPMOFs were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric-differential thermal analysis. The biotoxicity and imaging capability of the FA-NPMOFs were determined using HepG2 cells and embryonic and larval zebrafish. The delivery and photodynamic therapeutic effect of FA-NPMOFs were explored in transgenic zebrafish with doxycycline-induced HCC. Results: FA-NPMOFs were spherical in structure with good dispersion and water solubility. They showed low biotoxicity, emitted bright red fluorescence, and exhibited an excellent magnetic resonance imaging capability, both in vitro and in vivo. Meanwhile, the FA-NPMOFs exhibited a strong affinity for folate receptor (FR)-expressing cells and were delivered to the tumor site in a targeted manner. Moreover, HCC tumor cells were eliminated following laser irradiation. Conclusion: FA-NPMOFs can be used for dual-modality imaging and photodynamic therapy in HCC and show promise for use as a carrier in new therapies for HCC and other FR-positive tumors.
关键词： nanoscale gadolinium-porphyrin metal-organic frameworks,folic acid,hepatocellular carcinoma,photodynamic therapy,dual-modality imaging
更新于2025-09-04 15:30:14