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Hydrophilic Internal Pore and Hydrophobic Particle Surface of Organically Modified Mesoporous Silica Particle to Host Photochromic Molecules
摘要： The external surface of a mesoporous silica, MCM-41, was functionalized with phenyl group to obtain dual domain mesoporous silica particle (hydrophobic particle surface and hydrophilic mesopore) for photochrmoism of merocyanine/spiropyran. Merocyanine was adsorbed on MCM-41 and that functionalized with phenyl group by the photoinduced adsorption. The red hybrid of Ph-MCM-41 showed negative photochromism with a higher decolorization efficiency and a faster thermal colorization than the hybrid of MCM-41, suggesting the photogenerated spiropyran diffused into the hydrophobic surface.
关键词： Mesoporous silica,Surface modification,Negative photochromism
更新于2025-09-04 15:30:14
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Characteristic of silica xerogel from rice husk ash wastes sintered by microwave and conventional
摘要： An attempt was made to produce silica from an agricultural waste, rice husks ash (RHA), as well as studied them. The high percentage silica content from ash of rice husks was used as silica source for sodium silica solution. Different heating temperature, time and acid treatments was studied for silica extraction. The composite is characterized and its microwave properties is investigated after sintering from 400 to 1200 oC. The results show the existing phases crystoballite at 1100 oC in microwave sintering. Preliminary experiment for reflection losses of silica alumina composite show that there are relation between degree of crystallinity and their reflection loss.
关键词： rice husk ash,microwave,alumina,Silica xerogel,sintering
更新于2025-09-04 15:30:14
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Medium range order and configurational entropy of vitreous silica
摘要： Two potential sets and three thermodynamic regimes were utilized in molecular dynamics simulations in the preparation of the corresponding structures of vitreous silica. Medium range order characterized by means of basic ring distributions is robust to both thermodynamic conditions and/or potentials sets. A strong correlation between topology and geometry is demonstrated; the correlation is much stronger for simple clusters/small rings. Configurational entropy was evaluated by the ideal mixing of the structural units of the decomposed silica network. Entropy responds to alterations in the heating/cooling rates and its behaviour yields an excellent agreement with the experimental specific heat capacity drops observed at the glass transition. It is suggested the glass transition of the simulated glass should be identified with the change of entropy and not with a change of enthalpy as is conventionally done.
关键词： medium range order,configurational entropy,vitreous silica,glass transition,molecular dynamics simulations
更新于2025-09-04 15:30:14
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Amorphous Quantum Nanomaterials
摘要： In quantum materials, macroscopic behavior is governed in nontrivial ways by quantum phenomena. This is usually achieved by exquisite control over atomic positions in crystalline solids. Here, it is demonstrated that the use of disordered glassy materials provides unique opportunities to tailor quantum material properties. By borrowing ideas from single-molecule spectroscopy, single delocalized π-electron dye systems are isolated in relatively rigid ultra-small (<10 nm diameter) amorphous silica nanoparticles. It is demonstrated that chemically tuning the local amorphous silica environment around the dye over a range of compositions enables exquisite control over dye quantum behavior, leading to efficient probes for photodynamic therapy (PDT) and stochastic optical reconstruction microscopy (STORM). The results suggest that efficient fine-tuning of light-induced quantum behavior mediated via effects like spin-orbit coupling can be effectively achieved by systematically varying averaged local environments in glassy amorphous materials as opposed to tailoring well-defined neighboring atomic lattice positions in crystalline solids. The resulting nanoprobes exhibit features proven to enable clinical translation.
关键词： photodynamic therapy (PDT),optical super-resolution microscopy,organic dyes,amorphous silica nanoparticles
更新于2025-09-04 15:30:14
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Photocatalytic activities using a nanocomposite of mesoporous SiO2 and CdInSe-graphene nanoparticles under visible light irradiation
摘要： The new novel ternary mesoporous SiO2/CdInSe-graphene composites with diameters of approximately 8.08 nm have been fabricated through a self-assembly method. All physical tests demonstrated that the CdInSe-graphene was successfully uniformly distributed onto the surface of the ordered mesoporous silica particles. The obtained mesoporous SiO2/CdInSe-graphene composites exhibited good photocatalytic activity for degradation of both cationic-anionic organic dye groups, as well as the decomposition of the representative phenol group of the compound under visible light irradiation. Moreover, the photocatalytic evolution of hydrogen was studied for establishing a wider application of the as-fabricated SiO2/CdInSe-graphene catalyst in the case of energy conversion. This work indicated that the combination of the mesoporous silica and CdInSe-graphene enables achievements such as an enhancement photocatalytic performance, which has potential in industrial waste management and energy conversion.
关键词： Dye decomposition,CdInSe nanoparticles,Graphene-based nanocomposite,Gallic acid degradation,Mesoporous silica,Hydrogen production
更新于2025-09-04 15:30:14
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Formation and Evolution of Ultrathin Silica Polymorphs on Ru(0001) Studied with Combined in Situ, Real-Time Methods
摘要： Silica mono- and bilayer films on Ru(0001) can be physisorbed or chemisorbed, with ordered or vitreous structures, depending on the particular preparation procedures applied. Using the SMART spectro-microscope at BESSY-II with its capabilities for μ-spectroscopy, μ-diffraction, and LEEM imaging with lateral resolution below 5 nm, in situ and in real time and applied to identical areas, we have investigated the formation of these layers, defined and characterized their properties and their connected morphology, and followed their evolution. Two distinct chemisorbed monolayers and three bilayers (physisorbed crystalline and vitreous, and chemisorbed zigzag phases), and some transitions between them, have been studied. We found that, apart from the deposited silicon amount, the most important parameter for steering the evolution to a particular well-defined layer is the oxygen content at the Ru interface. Nucleation and growth of all layers are homogeneous on the scale of our resolution, leading to rather small domains (20 – 40 nm), mostly of the same phase, separated by defect lines. We discuss these and other basic findings in context and point out open questions. We also offer alternative recipes for the preparation of some phases, to obtain more homogeneous layers on a mesoscopic scale.
关键词： Silica films,SMART spectro-microscope,real-time methods,in situ,LEEM,chemisorbed,physisorbed,polymorphs,Ru(0001),μ-spectroscopy,μ-diffraction
更新于2025-09-04 15:30:14
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Visualization of Endogenous Hydrogen Sulfide in Living Cells based on Au Nanorods@Silica Enhanced Fluorescence
摘要： Hydrogen sulfide as a gas indicator molecule plays an important role in various human physiological processes. However, due to the high volatility and diffusivity of H2S in biological systems, it is very difficult to implement a precise assay for H2S detection. Compared with the destructive instrumental methods, assays based on fluorescence probes provide noninvasive and real-time detections of H2S in living cells. In this work, we presented a fluorescent nanoprobe based on dye-functionalized Au nanorods (NRs)@silica for sensitive and selective detection of H2S in vitro and living cells. With the metal enhanced fluorescence effect, the fluorescence turn-on and turn-off were controlled by the formation and disassembly of coordination compound between dyes and copper ions. Silica matrix was used to coat the Au NRs to prevent them from the biological cytotoxicity. The effects of the different distances between Au NRs and fluorophores on fluorescent enhancement were explored and approximately 5-fold fluorescence enhancement was obtained with a distance of 22 nm. A detection of limit of 17 nM was achieved. In addition, visualization of exogenous and endogenous H2S in living cells was validated.
关键词： nanoprobes,Au nanorods@silica,metal enhanced fluorescence,living cells,endogenous H2S
更新于2025-09-04 15:30:14
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Investigation on the Thermo-Optic Coefficient of Silica Fiber Within a Wide Temperature Range
摘要： In this paper, the thermo-optic coef?cient of silica ?ber is analyzed and measured within a wide temperature range of 0–1200 °C for the ?rst time. To obtain the thermo-optic coef?cient, experiments were carried out by using ?ber optic extrinsic Fabry–Perot interferometers (EFPIs) embedded in silica ?ber. The optical cavity lengths of the EFPIs were measured with white-light interferometry. The experimental results show that the ?rst and second orders of the thermo-optic coef?cient are 1.090 × 10?5/°C and 1.611 × 10?9/°C2, respectively. The quadratic model for the temperature dependence of the basic optical parameter, the refractive index, is rigorous within a wide temperature range. Furthermore, this paper also provides a temperature calibration method for extrinsic Fabry–Perot interferometric temperature sensors. The temperatures measured by the sensors are in excellent agreement with those measured by the reference thermocouple. Hence, this calibration method is promising for temperature sensors with a wide working temperature range.
关键词： thermo-optic coef?cient,Fabry-Perot interferometers,silica ?ber
更新于2025-09-04 15:30:14
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<i>In vivo</i> Imaging-Guided Nanoplatform for Tumor Targeting Delivery and Combined Chemo-, Gene- and Photothermal Therapy
摘要： Currently, a large number of anti-tumor drug delivery systems have been widely used in cancer therapy. However, due to the molecular complexity and multidrug resistance of tumors, monotherapies remain suboptimal. Thus, this study aimed to develop a multifunctional theranostic nanoplatform for effective cancer therapy. Methods: Folic acid-modified silver sulfide@mesoporous silica core-shell nanoparticle was first modified with desthiobiotin (db) on the surface, then doxorubicin (DOX) was loaded into pore. Avidin was employed as "gatekeeper" to prevent leakage of DOX via desthiobiotin-avidin interaction. Db-modified survivin antisense oligonucleotide (db-DNA) which could inhibit survivin expression was then grafted on avidin at the outer layer of nanoparticle. DOX release and db-DNA dissociation were simultaneously triggered by overexpressing biotin in cancer cells, then combining PTT from Ag2S QD to inhibit tumor growth. Results: This nanoprobe had satisfactory stability and photothermal conversion efficiency up to 33.86% which was suitable for PTT. Due to the good targeting ability and fluorescent anti-bleaching, its signal still existed at the tumor site after tail vein injection of probe into HeLa tumor-bearing nude mice for 48 h. In vitro and in vivo antitumor experiments both demonstrated that drug, gene and photothermal synergistic therapy significantly enhanced antitumor efficacy with minimal systemic toxicity. Conclusion: Our findings demonstrate that this novel nanoplatform for targeted image-guided treatment of tumor and tactfully integrated chemotherapy, photothermal therapy (PTT) and gene therapy might provide an insight for cancer theranostics.
关键词： mesoporous silica,photothermal therapy,fluorescence imaging,gene therapy,drug delivery system
更新于2025-09-04 15:30:14
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The effect of the medium-range configuration on the atomistic fracture behaviour of vitreous silica
摘要： Using molecular dynamics simulations, we prepare vitreous silica by quenching molten silica to ambient temperature. Varying the quenching rate, we show that the latter barely influences the short-range order, whereas the medium-range configuration is significantly affected. We subject the prepared silica specimens to tension until fracture occurs and demonstrate the effect on the material behaviour. We evaluate the medium-range configuration in terms of the ring statistics of the glass network structure. Linking the ring statistics with the deformation and fracture behaviour of vitreous silica, we provide a topologically motivated explanation of the material behaviour.
关键词： quenching rate,fracture behaviour,vitreous silica,medium-range configuration,molecular dynamics
更新于2025-09-04 15:30:14