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Oxidation/reduction control of the VO2 nanoparticle in the nano-confined space of the hollow silica nanoparticle
摘要： Vanadium dioxide (VO2) exhibits a good thermochromic property which can be used in a smart window. To improve its poor visible transparency, immobilization of the VO2 nanoparticles on the silica shell of hollow nanoparticles was proposed. In addition to improving the particle dispersibility of the VO2 and to reducing stress from repeated phase transitions of the VO2 between monoclinic and tetragonal, the hollow interior can reduce any undesirable oxidation of the VO2 to V3O7, V2O5, etc., along with the thermal decomposition behavior of organic compounds around the vanadium atom. The hollow silica nanoparticles with micropores (less than 2 nm) were prepared by a previously-reported template method. Through the pores, the vanadium precursor with a chelate ligand solution penetrates into the hollow interior. The vanadium intermediate formed by adding water was then captured by the silica shell. During the crystallization process under a nitrogen atmosphere, 10-30 nm of VO2 particles were immobilized on the silica shell with a high dispersibility by optimization of the vanadium precursor concentration, and ratios of vanadium/water and vanadium/hollow silica nanoparticles. The VO2/hollow silica nanoparticles in water exhibited a higher visible transparency than that of the commercial VO2. In addition, their thermochromic property in the infrared region was close to that of the commercial one.
关键词： Thermochromic,Hollow silica nanoparticle,Vanadium dioxide,Micropore
更新于2025-09-23 15:23:52
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Microneedle fractional radiofrequency-induced micropores evaluated by in vivo reflectance confocal microscopy, optical coherence tomography, and histology
摘要： Background: Microneedle fractional radiofrequency (MNRF) is a minimally invasive technique that delivers radiofrequency (RF) energy into the skin via microneedles. Reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) enable the characterization of device-tissue interactions in in vivo skin. The aim of this study is to describe MNRF-induced micropores using RCM and OCT imaging. Materials and methods: Five healthy participants were treated with a 7 × 7 array of 1500 μm microneedles on two adjacent areas of the right hip. One area received MNRF using high RF energy while the other underwent MNRF at low RF energy. Micropore morphology was evaluated qualitatively and quantitatively with RCM and OCT. To relate imaging with histology, one participant underwent punch biopsy in both areas. Results: Reflectance confocal microscopy visualized shape, content, and thermal-induced coagulation zone (CZ) of MNRF micropores. At high RF energy, micropores showed concentric shape, contained hyperreflective granules, and coagulated tissue from epidermis to dermo-epidermal junction (diameter 63-85 μm). Micropores at low RF energy, presented with a stellate shape, no content and CZs that were visible only in epidermis (CZ thickness 9 μm, IQR 8-21 μm). Evaluating OCT, high RF energy showed deeper (150 μm), more easily identifiable micropores compared to low RF energy micropores (70 μm). Histology showed tissue coagulation to a depth of 1500 μm at high RF energy, while at low RF energy, disruption was only visible in epidermis. Conclusion: Microneedle fractional radiofrequency micropores show distinct characteristics in both RCM and OCT, depending on RF energy. These in vivo imaging modalities are complementary and allow combined, qualitative, and quantitative evaluation.
关键词： microneedle fractional radiofrequency,histology,optical coherence tomography,micropore,reflectance confocal microscopy
更新于2025-09-19 17:15:36
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Time evolution of angular momentum coherent state derived by virtue of entangled state representation and a new binomial theorem
摘要： Objective: This study explored the clinical efficacy and hemodynamic effects of the micropore stent graft (MSG) that could promote aortic remodeling and preserve important organ branches. Methods: We conducted a retrospective analysis of 26 patients who underwent endovascular repair using an MSG for DeBakey types I and III TAD at our center between December 2014 and December 2017. The main efficacy parameters were rupture of the false lumen or dissection-related death, conversion to open repair, secondary reintervention, branch vessel patency, and the hemodynamic effects of TAD at 12 months. Results: Dissection rupture, dissection-related mortality, conversion to open repair, and secondary reintervention rates at 12 months were 0, 3.9, 0, and 0%, respectively. In the 24 patients with more than 6 months of follow-up, micropore stents were implanted to cover 39 openings in aortic arch branches, 91.7% (22/24) presented with complete thrombosis in the false lumen, 8.3% (2/24) presented with partial thrombosis in the false lumen, 35.2% (6/17) presented with a thrombus in the false lumen that was completely absorbed, and all 39 branches were patent. After surgery, pressure peak value and fluctuation along with the degree and range of unstable blood flow in the aortic lumen decreased. Conclusions: For type I and type III thoracic artic dissection, endovascular treatment with an MSG may be a safe and effective treatment option with a good midterm outcome.
关键词： endovascular repair,micropore stent graft,patency rate,thoracic aortic dissection,hemodynamics
更新于2025-09-11 14:15:04
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Composited micropores constructed by amorphous TiO2 and graphene for degrading volatile organic compounds
摘要： The adsorption ability and photoactivity of photocatalysts directly determine the mineralization efficiency of volatile organic compounds. In this study, a 2D–2D microporous structure of amorphous TiO2 nanoparticles and graphene (GR) was constructed to simultaneously enhance the adsorption ability and charge separation efficiency of catalysts. N2 adsorption–desorption, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction measurements were conducted to investigate the physical properties of the prepared samples. The atmospheric surface photovoltage (SPV) was utilized to study the separation process of the photogenerated charge carriers. Toluene was chosen as the model agent to estimate the adsorption ability and photoactivity of the samples. Results showed that the amorphous TiO2 nanoparticles homogeneously deposited onto the GR surface and hence formed a 2D–2D microporous structure. Although the surface area of the GR–TiO2 compositions increased by only 4–8% relative to that of microporous TiO2 alone, the amount of adsorbed toluene for the GR–TiO2 compositions was 156–193% times higher than that for the microporous TiO2. The SPV result proved that the GR significantly enhanced the intrinsic separation of the photogenerated charge carriers. The contribution of O2 and the GR to the charge separation was dependent on the weight addition ratio of the GR. The GR dominated the charge separation process as its weight addition ratio ≥5%. Given the advantages in adsorption ability and photoactivity, toluene showed mineralization efficiencies for the composite with 5.0 wt% GR of 1.4 and 2.7 folds those of microporous TiO2 and P25, respectively, after 96 min irradiation.
关键词： Charge carriers,Surface photovoltage,Micropore,Mineralization,Adsorption
更新于2025-09-10 09:29:36