Papers by Keyword: Nanospheres

Abstract: Herein, silica nanoparticles (SiO₂ NPs) were synthesized from a waste product of the zirconium carbide facility (WPZF). Firstly, the WPZF was characterized by using physical and chemical methods like X-ray powder diffraction (XRD), field emission scanning electron microscope (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), and energy dispersive X-ray analysis (EDXA) methods. Then WPZF proceeded via chemical reagents to synthesize SiO₂ NPs by using the sol-gel method. Obtained SiO₂ NPs were characterized by using XRD, SEM, EDXA, and transmission electron microscopy (TEM) methods. The yield of SiO₂ NPs reached up to 96.5% and particles were spherical with a diameter of 20 ± 3 nm. Most importantly observed SiO₂ NPs in this procedure has an amorphous structure.

Abstract: The paper presents the synthesis and investigation of zirconium oxide (ZrO₂) nanoparticles that were synthesised by precipitation method with the effects of the temperatures of reaction on the particles size, morphology, crystallite sizes and stability at high temperature. The reaction temperature effect on the particle size, morphology, crystallite sizes and stabilized a higher temperature (tetragonal and cubic) phases was studied. Thermal decomposition, band structure and functional groups were analyzed by Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Thermo-gravimetric analysis (TGA) and Fourier transform infrared (FT-IR). The crystal structure was determined using X-ray diffraction. The morphology and the particle size were studied using (SEM) and (TEM). The shaped particles were confirmed through the SEM analysis. The transmission electron microscopic analysis confirmed the formation of the nanoparticles with the particle size. The FT-IR spectra showed the strong presence of ZrO₂ nanoparticles.

Abstract: The carbon nanotubes (CNTs) modified by the carbon particles with diameter of 120-180 nm are prepared by using hydrocarbon ion deposition techniques. Based on the investigation of scanning electron microscopy and transmission electron microscopy, the CNTs are decorated by some nanospheres with size of 120-180 nm randomly, and the full CNTs surface besides the area of nanosphere is coated by the graphene stacks with size of 10-15 nm. The nanospheres are composed of several nanoparticles of graphene stacks and are seamless connected with graphene stacks. The sparse distribution CNTs on Si substrate is crucial for the formation of carbon nanospheres. The formation of carbon nanospheres proceeds through the following three stages: the formation of graphene nanoparticle on CNTs surface and silicon substrate – the migration of active hydrocarbon groups towards the surface of the CNTs deposition zone at high temperature – the formation of carbon nanospheres by the aggregating hydrocarbon active groups.

Abstract: We develop a simple and competitive fabrication of antireflective (AR) films with high-ordered nanostructure arrays on polycarbonate (PC) substrate by using gas-assisted hot embossing and a self-assembled technique. In this method, a self-assembled monolayer of polystyrene (PS) nanospheres is well-patterned on glass substrates as the first template. Subsequently, we use the plasma sputtering to deposit a conductive layer onto the surface of nanosphere (NS) patterned substrates, and then, electroforming is applied to fabricate a nickel mold with an inverse shape of nanospheres. In the last step, a unique glass transition is utilized to duplicate nanostructures on PC films via gas-assisted hot embossing. Not only in visible light but in near infrared, the optical properties of this AR film are similar or better than for other methods. This fabrication process also has great potential in industry, with its simplicity, large-area but low-cost.

Abstract: Objective To obtain immobilized nanomaterials with good performance, the preparation condition of chitosan nanospheres by miniemulsion crosslinking method was optimized. Methods The chitosan nanospheres were synthesized by miniemulsion crosslinking method with Span80 and Tween80 as the emulsifier, glutaraldehyde as the crosslinker, n-hexane and paraffin liquid as oil phase,chitosan acetic acid solution as aqueous phase. The particle size was measured by Zetasizer nanoanalyzer. Results The results of the univariate tests show that the optimal preparation condition of chitosan nanospheres can be obtained when water/oil volume ratio is 3:2. The size distribution of chitosan nanospheres is 18.17nm to 190.1nm. Conclusion The chitosan nanospheres by miniemulsion crosslinking method are suitable materials as enzymes and proteins immobilized carrier.

Abstract: The La-doped porous In₂O₃ nanospheres were prepared by a simple hydrothermal method, and La³⁺ accounted for 3 mol% of the In³⁺. The La exists and has been doped in the lattice of In₂O₃ characterized respectively by the means of energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), the morphology of the samples with uniform nanospheres observed by field-emission scanning electron microscopy (FESEM). Moreover, the sensor exhibits higher response properties compared with pure porous In₂O₃ nanospheres towards different acetone concentration at operating temperature 300 °C. The response and recovery times is about 13 s and 8 s to 50 ppm acetone.

Abstract: In this study, Photosan (PS) was loaded onto hollow silica nanospheres using one-step wet chemical-based synthetic route method. Polydispersive index of the Photosan-loaded hollow Silica Nanospheres (PS-loaded NSs) is 0.121±0.01. The photobiological activity of the PS-loaded NSs was evaluated on human cholangiocarcinoma QBC939 cells. Cells were incubated with free PS or PS-loaded NSs for 2 h and then washed with phosphate-buffered saline. Culture medium was added to the wells containing the cells. Finally, the cells were exposed to red light (630 nm) with a light dose of 10J/cm². The cellular viability was determined after 24 h of incubation. PS-loaded NSs and free PS eliminated about 96.4%±2.0% and 54.7%±1.9% of QBC939 cells, respectively. The phototoxicity was time dependent up to 2 h and concentration dependent at 1-7.5 mg/l. The cells viability decreased with the increase of the light dose in the range of 5-15 J/cm². In conclusion, PS-loaded NSs are the release systems that promise photodynamic therapy use.

Abstract: An effective and optimized method for synthesis silica sol nanospheres by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in the presence of aqueous alcohol solution with ammonia as catalyst was described. Under this experiment condition, monodisperse and uniform-size silica sol spheres with average diameters from 38-95nm were obtained. Here, we successfully controlled the size and shape of silica sol by fine adjusting the reaction parameters such as concentration of TEOS, value of R (H2O/TEOS) and ammonia concentration. On the basis of the experiment results, it was found that sphere size declined as the concentration of TEOS decreased. Also with the increment of ammonia concentration, the diameter of silica sol decreased slightly. However, higher R (H2O/TEOS) value would lead to larger sphere size in the range of 62-95nm. The resulting silica sol was determined by Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier transformed infrared (FT-IR).

Abstract: Spherical V-MCM-41s with different diameter are synthesized by direct hydrothermal method through the precise control over the molar ratio of NaOH/TEOS. Vanadium supported on spherical MCM-41s is also prepared by impregnation methods. They are used as heterogeneous catalysts for the oxidation of styrene with H₂O₂ as oxidant. The results suggest that all catalysts have high catalytic activity, which increases with their diameter decreasing.

Abstract: A rapid solvent-free melting route has been successfully developed for the synthesis of tungsten nitrides with lamellar and solid spherical nanostructures which have considerably different surface areas (106.4 m² g^-1 contrast to 8.3 m² g^-1) by the reaction of WCl6 and NaNH2 at 220 °C for 2-5 h directly, and it is found that the heat insulating property of reaction container plays important roles in the composition, phase, and morphologies of the nitrides. The products were analyzed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS). Their thermal stability and surface area were measured by thermogravimetric analysis (TGA) and BET, respectively. Finally, the possible formation mechanism of tungsten nitrides with different morphologies was also investigated.