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51.
Maleic anhydride was grafted by long-chain alcohols (1-hexadecanol, 1-octadecanol) to amphiphilic mono-L cis-butene dicarboxylates (L = hexadecyl, octadecyl), i.e., MAH, MAO, respectively. Subsequently, corresponding amphiphilic cerium
complexes with these two mono-L cis-butene dicarboxylate ligands (Ce(L')3, L'= MAH, MAO) were synthesized and behaved as the precursors to prepare CeO2 nanoparticles for both of which can form nanosized micelle-like aggregates by special self-assembly in the wet chemical process.
The nanoparticles were further characterized by Fourier transform-infrared spectroscopy (FTIR), Diffuse reflectance ultraviolet-visible
spectra (DRUVS), scanning electron microscope (SEM), transmission electron microscope (TEM), and x-ray diffraction (XRD).
Both the CeO2 nanoparticles are in a cubic fluorite structure and present regular and well-dispersion club-like morphology with average
particle size in the range of 40–70 nm. Besides, the strong ultraviolet–visible absorption for these CeO2 nanoparticles can be found at the long-wavelength ultraviolet to visible region of 200–500 nm. 相似文献
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54.
Olin T. Mefford Robert C. Woodward Jonathan D. Goff T.P. Vadala Tim G. St. Pierre James P. Dailey Judy S. Riffle 《Journal of magnetism and magnetic materials》2007
Biocompatible, hydrophobic ferrofluids comprised of magnetite nanoparticles dispersed in polydimethylsiloxane show promise as materials for the treatment of retinal detachment. This paper focuses on the motion of hydrophobic ferrofluid droplets traveling through viscous aqueous media, whereby the movement is induced by gradients in external fields generated by small permanent magnets. A numerical method was utilized to predict the force on a spherical droplet, and then the calculated force was used to estimate the time required for the droplet to reach the permanent magnet. The calculated forces and travel times were verified experimentally. 相似文献
55.
Wuyou Fu Shikai Liu Wenhua Fan Haibin Yang Xiaofen Pang Jing Xu Guangtian Zou 《Journal of magnetism and magnetic materials》2007
Spinel CoFe2O4 coating on the surface of hollow glass microspheres of low density was synthesized by co-precipitation method. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectroscopy (EDS). The results show that CoFe2O4 coating on hollow glass microspheres can be achieved, and the coating layers are constituted by CoFe2O4 nanoparticles of mean size ca. 10 nm. The as-synthesized powder materials were uniformly dispersed into the phenolic cement, then the mixture was pasted on metal plate with the area of 200 mm×200 mm as the test plate. The test of microwave absorption was carried out by the radar-absorbing materials (RAM) reflectivity far field radar cross-section (RCS) method. The results indicate that the coated CoFe2O4/hollow glass microspheres composites can be applied in lightweight and strong absorption microwave absorbers. 相似文献
56.
Silver-decorated silica spheres of submicrometer-sized silica spheres with a core-shell structure were obtained based on a seed-mediated growth process, where silver nanoparticles were firstly formed from reducing Ag+ to Ag0 in N,N-dimethylformamide (DMF) in the presence of poly(vinylpyrrolidone) (PVP) as protective agent under ultrasound irradiation, followed by the growth of silver shell served silver nanoparticles as nucleation sites and formaldehyde as reducer. The results revealed that the terms of PVP addition and ultrasonic surroundings had great influence on the fabrication of silver seeds. 相似文献
57.
Recent studies demonstrated that the process to produce metal and oxide nanoparticles by laser ablation of consolidated microparticles is a convenient and energy-efficient way to prepare nanoparticles. In this work, the novel process is applied to nanoparticle synthesis in the liquid environment and the results are compared with those by the gas-phase process. Metal and oxide nanoparticles are synthesized by pulsed laser ablation of the compacted metal microparticles using a Q-switched Nd:YAG laser in water. It is shown that the process is effective for preparing nanoparticle suspensions having relatively uniform size distributions. While the laser fluence and the degree of compaction strongly influence the size of the produced nanoparticle in air, the sedimentation time is shown to be the most critical factor to determine the mean size of the suspended particles. 相似文献
58.
Chengyu Wang 《Applied Surface Science》2007,253(10):4768-4772
Hydrophobic vaterite nanoparticles were prepared via crystallization of CaCO3 with oleic acid in methanol by mimicking the process of biomineralization. The molar ratio of oleic acid to calcium ion was varied from 0.1 to 0.5. By changing the concentration of the oleic acid, CaCO3 particles with different shapes and polymorphism were obtained. High concentration of the oleic acid gave stable vaterite crystals, the polymorph of which did not change when the composite was kept in water for more than one week. Fourier transform infrared spectroscopy (FT-IR) and TGA analysis of the obtained product indicated that the oleic acid was bound to the crystalline CaCO3. The contact angle of the modified vaterite reached 122°. We have succeeded in crystallization of hydrophobic CaCO3 nanoparticles in situ. 相似文献
59.
Synthesis of poly(PDL-GA) copolymers is successfully achieved via enzymatic catalysis starting from ω-pentadecalactone and ethyl glycolate. In the copolymers PDL and GA units show a significant tendency to an alternating arrangement. All copolyesters display a high degree of crystallinity (χc ≈ 70%) regardless of their composition (GA content: 0–27 mol%). Analysis of melting point depression by the Wendling–Suter model suggests inclusion of GA units in PPDL-type crystals. Accordingly WAXS results show that, with increasing GA unit content, the PPDL unit cell undergoes a gradual increase of c-axis (chain axis) periodicity, compatible with the insertion of GA units within the crystallizing PDL sequences. Poly(PDL-GA) copolymers combine typically hydrophobic (PDL) and hydrophilic (GA) monomers and are promising new tuneable drug-delivery systems for medical applications. In this perspective, poly(PDL-GA) nanoparticles are fabricated and characterized. 相似文献
60.
Magnetic nanocomposite material composed of poly vinyl alcohol encapsulated Ni0.2Ca0.8Gd0.08Fe1.92O4 was synthesized by a two step chemical method including sol-gel combustion and solvent casting technique. The obtained samples were characterized by powder X-ray diffraction; transmission electron microscopy and Fourier transform infrared spectroscopy. The results of spectroanalysis pointed towards the existence of a considerably feasible interaction between the polymer chain and the ferrite particles. The dc magnetization measurements divulged that both pristine and the nanocomposite samples under applied magnetic field exhibit no hysteretic behavior at room temperature, symptomatic of the superparamagnetic behavior. The departure of field cooled and zero field cooled curves in the moment-versus-temperature plot further confirmed the room temperature superparamagnetic behavior. The extrapolation of the slope of the curves to M=0 imparted the average value of Curie temperature at ∼323 K (50 °C) for both the samples, suggestive of the efficacy of the material for finding application in self controlled hyperthermia. 相似文献