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Synthesis of Silica Microspheres—Inspired by the Formation of Ice Crystals—With High Homogeneous Particle Sizes and Their Applications in Photonic Crystals
摘要： Silica microspheres (SMs) must possess the performances of desirable monodispersity, narrow particle size distribution, and high sphericity for preparing photonic crystals (PCs) and other materials such as microspheres reference material, etc. We have adopted the techniques of increasing reactant concentration and raising the temperature to improve the synthesis rate of SMs, gaining inspiration from the formation mechanism of ice crystals. SMs with uniform particle sizes (polydispersity index less than 0.05) and good spherical features were fabricated through homogeneous nucleation. The mathematical relationship between particle sizes of SMs and reactant concentrations is further fitted. High accuracy of the regression equation is verified by an F-test and verification experiment. Highly ordered PCs (the stacking fault is about 1.5%, and the point defect is about 10?3) with dense stacked opal structures have been obtained by self-assembly of SMs. In addition, highly ordered PCs (the stacking fault is about 3%, and the point defect is about 10?3) with non-dense packed opal structure and inverse opal structure were successfully prepared. PCs of inverse opal structure were used to examine their response characteristics to identify ethanol, exhibiting good performance. Our research may provide significant inspiration for the development of other sorts of microspheres.
关键词： photonic crystals,silica microspheres,homogeneous nucleation,self-assembly
更新于2025-09-09 09:28:46
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Silica Nanoparticles with Up-conversion Fluorescence Based on Triplet-Triplet Annihilation Mechanism for Specific Recognition of Apoptosis Cells
摘要： Discriminating of live and apoptotic cells is a crucial task in the research of pharmacology, biology, pathology, and medicine science. Recently, up conversion (UC) luminescent materials have appealed much attention due to their unique ability to convert low energy excitation photons to high energy ones. However, UC fluorescence has not been employed in the field of discriminating of live and apoptotic cells. We presented a facile, and cost-less St?ber method to fabricate robust silica nanoparticles (SiO2 UCNPs) exhibiting several merits, such as narrow size distribution, and UC luminescence. SiO2 UCNPs could discriminate live and apoptosis cells by taking advantage of the unique surface property of SiO2 UCNPs for the first time. This work is also the first demonstration of the use of single photon excited UC fluorescence derived from nanoparticles for biological recognition of a specific type of cells.
关键词： Apoptosis Cells,Triplet-Triplet Annihilation Mechanism,Silica Nanoparticles,Up-conversion Fluorescence
更新于2025-09-09 09:28:46
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Synthesis of silica microspheres on silicon-modified carbon foams under ablation
摘要： Silica microspheres (SMs) were in situ synthesized in silicon-modified porous carbon foams (SCFs) by an economic and efficient technique – high temperature oxyacetylene torch ablation. The microstructure and formation mechanism of SMs were analyzed in detail. Results showed that the resultant SMs generally were several microns in diameter, and mainly distributed in the ablation center zone. The formation mechanism was governed by the vapor–liquid–solid principle during the process of ablation and cooling. The influence of the ablative flame on the physicochemical property of SCFs was the leading cause of the bizarre SMs.
关键词： ablation,Silica microsphere,carbon foam
更新于2025-09-09 09:28:46
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Slow crack growth in silica aerogels: A review
摘要： The sub-critical crack growth in hydrophobic (as prepared) and hydrophilic (oxidized) silica aerogel was studied using the Dynamic fatigue experiment and the Double-Cleavage-Drilled-Compression test (DCDC). The effect of oxidation treatment is clearly evidenced. The temperature and water vapor content dependence on the crack growth rate is measured between 22 °C and 110 °C with relative air moisture ranging from 5 to 80% RH. Like dense silica, crack growth velocities were found to decrease when increasing the temperature at a constant water vapor concentration. Surprisingly, the crack velocity also decreases when increasing water vapor content at constant temperature. Such a behavior is contrary to expected results usually encountered in glasses. We assume that a capillary condensation phenomenon of water vapor inside the aerogel porosity takes place, inducing internal compressive stresses.
关键词： Silica aerogels,Slow crack growth,Stress corrosion effect
更新于2025-09-09 09:28:46
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Photothermal Therapy Employing Gold Nanoparticle- Loaded Macrophages as Delivery Vehicles: Comparing the Efficiency of Nanoshells Versus Nanorods
摘要： Macrophages (Ma) loaded with gold-based nanoparticles, which convert near infrared light to heat, have been studied as targeted transport vectors for photothermal therapy (PTT) of tumors. The purpose of the experiments reported here was to compare the efficacy of gold-silica nanoshells (AuNS) and gold nanorods (AuNR) in macrophage-mediated PTT. Photothermal therapy efficacy was evaluated in hybrid glioma spheroids consisting of human glioma cells and either AuNS- or AuNR-loaded Ma, designated MaNS and MaNR, respectivly. Spheroids were irradiated for 10 minutes with light from an 810-nm diode laser at irradiances ranging from 0 to 28 W/cm2. Photothermal therapy efficacy was determined from spheroid growth over a 14-day period. The uptake by Ma of pegylated AuNR (3.9 ± 0.9 %) was twice that of pegylated AuNS (7.9 ± 0.7%). Hybrid spheroids consisting of a 5:1 ratio of glioma cells to loaded Ma exhibited significant growth inhibition with MaNS when subjected to irradiances of 7 W/cm2 or greater. In contrast, no significant growth inhibition was observed for the MaNR hybrid spheroids at this 5:1 ratio, even at the highest irradiance investigated (28 W/cm2). Although AuNR were taken up by Ma in larger numbers than AuNS, MaNS were shown to have greater PTT efficacy compared to MaNR for equivalent numbers of loaded Ma.
关键词： photothermal therapy,glioma,murine macrophages,gold-silica nanoshells,gold nanorods
更新于2025-09-09 09:28:46
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Temperature-Dependent Refractive Index of Quartz at Terahertz Frequencies
摘要： Characterisation of materials often requires the use of a substrate to support the sample being investigated. For optical characterisation at terahertz frequencies, quartz is commonly used owing to its high transmission and low absorption at these frequencies. Knowledge of the complex refractive index of quartz is required for analysis of time-domain terahertz spectroscopy and optical pump terahertz probe spectroscopy for samples on a quartz substrate. Here, we present the refractive index and extinction coefficient for α-quartz between 0.5 THz and 5.5 THz (17–183 cm?1) taken at 10, 40, 80, 120, 160, 200 and 300 K. Quartz shows excellent transmission and is thus an ideal optical substrate over the THz band, apart from the region 3.9 ± 0.1 THz owing to a spectral feature originating from the lowest energy optical phonon modes. We also present the experimentally measured polariton dispersion of α-quartz over this frequency range.
关键词： Terahertz,Quartz,Refractive index,Dispersion,Silica,Optical pump terahertz probe OPTPS,Time-domain spectroscopy,Polariton,SiO2
更新于2025-09-09 09:28:46
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Multi-objective Optimization of Rotary Ultrasonic Machining Parameters for Quartz Glass Using Taguchi-Grey Relational Analysis (GRA)
摘要： Rotary ultrasonic machining has the capability to process the materials which are very hard, brittle and electrically non-conductive, with efficiency and cost-effectiveness. The current investigation is focused on the use of Taguchi-Grey relational analysis to improve the machining performance of Rotary ultrasonically machined quartz glass. Ideal machining parameters were calculated by grey relational grade calculated in grey relational analysis which was designed for simultaneous optimization of material removal rate and surface roughness. The rotary ultrasonic machining parameters setting with tool rotational speed of 5000 rpm, tool feedrate of 0.75 mm/min, and ultrasonic power of 55% were found to have the highest grey relation grade resulting in the high material removal rate and low surface roughness of the processed material. The tool feed rate was found to be the most critical parameter followed by ultrasonic power and tool rotational speed on the rotary ultrasonic machining characteristics. Confirmatory experiments were also executed to authenticate the forecasted results obtained from the Taguchi-Grey relational analysis. Furthermore, the microstructural investigation was carried out to comprehend the mechanism of material removal in the rotary ultrasonic machining of quartz glass at optimum parameter setting. It was found that the material was removed in the brittle mode and abrasion during the machining at optimum parameter setting. The sharp cutting edges of the diamond grits have caused the abrasive wear and brittle fracture of the quartz material. The interlinking of the cracks results in the pullout of the grains and consequently deeper grooves are formed on the machined surface.
关键词： RUM,Fused silica,Taguchi method,Machining performance,Grey relational analysis,Microstructural investigation
更新于2025-09-09 09:28:46
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Dual-Emission Fluorescent Microspheres for the Detection of Biothiols and Hg2+
摘要： Dual-emission nanosensor for Hg2+ detection was prepared by coupling CA-AEAPMS on the surface of RBS-doped modified silica microspheres. The CA-AEAPMS was synthesized by using N-(β-aminoethyl)-γ-aminopropyl methyldimethoxysilane (AEAPMS) and citric acid as the main raw material. The obtained nanosensor showed characteristic fluorescence emissions of Rhodamine B (red) and CA-AEAPMS (blue) under a single excitation wavelength (360 nm). Upon binding to Hg2+, only the fluorescence of CA-AEAPMS was quenched, resulting in the ratiometric fluorescence response of the dual-emission silica microspheres. This ratiometric nanosensor exhibited good selectivity to Hg2+ over other metal ions, because of the amide groups on the surface of CA-AEAPMS serving as the Hg2+ recognition sites. The ratio of F450/F580 linearly decreased with the increasing of Hg2+ concentration in the range of 0 to 3 × 10?6 M, and a detection limit was as low as 97 nM was achieved. Then, the addition of three thiol-containing amino acids (Cys, Hcy, GSH) to the quenched fluorescence solution with Hg2+ can restore the fluorescence, and the detection limits of the three biothiols (Cys, Hcy, GSH) are 0.133 μM, 0.086 μM, and 0.123 μM, respectively.
关键词： dual-emission,fluorescence,silica microspheres
更新于2025-09-09 09:28:46
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Hydroxypropyl Methacrylate Interaction and Chitosan Coating for Enhanced UV Detection Sensitivity of Colloidal Nanoparticles in Capillary Electrophoresis Analysis
摘要： The binding interactions between silica (SiO2), titania (TiO2) or polymeric nanoparticles with hydroxypropyl methacrylate (HPMA) were investigated for enhancing the ultraviolet (UV) detection sensitivity of these nanoparticles in capillary electrophoresis (CE) analysis. HPMA interacted with colloidal SiO2 nanoparticles, producing a larger CE-UV peak at a slightly shorter migration time. An increase in particle size with HPMA binding was validated using dynamic light scattering. The interaction was selective as HPMA did not interact with TiO2 nanoparticles in aqueous suspension. Chitosan coating of SiO2 or TiO2 nanoparticles produced significantly larger hydrodynamic diameters to further enhance the sensitivity of their UV detection. The analytical technique, which involves coating SiO2 nanoparticles with chitosan first and binding with HPMA next, is novel. It has allowed us to achieve a significant enhancement of 50 folds in detection sensitivity.
关键词： Titania,Colloid,Nanoparticles,Capillary electrophoresis,Chitosan,Hydroxypropyl methacrylate,Silica,Polymer,Dynamic light scattering
更新于2025-09-09 09:28:46
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Mesoporous silica modified luminescent Gd2O3:Eu nanoparticles: physicochemical and luminescence properties
摘要： Highly colloidal Gd2O3:Eu nanoparticles (core-NPs) were synthesized by thermal decomposition via weak base at low temperature. The sol–gel chemical process was employed for silica layer surface coating to increase solubility, colloidal stability, biocompatibility, and non-toxicity at the ambient conditions. XRD results indicate the highly puri?ed, crystalline, single phase, and cubic phase Gd2O3 nanocrystals. TEM image shows that the mesoporous thick silica layer was effectively coated on the core nanocrystals, which have irregular size with nearly spherical shape and grain size about 10–30 nm. An absorption spectra and zeta potential results in aqueous media revealed that solubility, colloidal stability, and biocompatibility character were enhanced from core to core–shell structure because of silica layer surface encapsulation. The samples, demonstrated excellent photoluminescence properties (dominant emission 5D0 → 7F2 transition in the red region at 610 nm), indicated to be used in optical bio-detection, bio-labeling, etc. The photoluminescence intensity of the silica shell modi?ed core/shell NPs was suppressed relatively core-NPs; it indicates the multi-photon relaxation pathways arising from the surface coated high vibrational energy molecules of the silanol groups. The core/nSiO2/mSiO2 nanocrystals display strong emission (5D0 → 7F2) transition along with excellent solubility and biocompatibility, which may ?nd promising applications in the photonic based biomedical ?eld.
关键词： silica,Gadolinium oxide,Biocompatible,Luminescence properties,Zeta potential,Mesoporous
更新于2025-09-09 09:28:46