This paper investigates the enhancement of heat transfer coefficient and Nusselt number of a nanofluid containing nanoparticles (γ-AL2O3) with a particle size of 20 nm and volume fraction of 0.1%-0.3% (V/V). Effects of temperature and concentration of nanoparticles on Nusselt number changes and heat transfer coefficient in a double pipe heat exchanger with counter turbulent flow are investigate...

One-dimensional γ-Al2O3 nanofibers were modified with Nb2O5 to be used as an efficient heterogeneous catalyst to catalyze biomass into 5-hydroxymethylfurfural (5-HMF). At low Nb2O5 loading, the niobia species were well dispersed on γ-Al2O3 nanofiber through Nb-O-Al bridge bonds. The interaction between Nb2O5 precursor and γ-Al2O3 nanofiber results in the niobia species with strong Lewis acid si...

the knoevenagel condensation of aromatic aldehydes with barbituric acid, dimedone and malononitrile occurred in the presence of bf3/nano-γ-al2o3 at room temperature in ethanol. this catalyst is characterized by powder x-ray diffraction (xrd), fourier transform infrared spectroscopy (ft-ir), thermal gravimetric analysis (tga), field emission scanning electron microscopy (fesem) and energy-disper...

Liquid drops on deformable soft substrates exhibit quite complicated wetting behavior as compared to those rigid solid substrates. We report a of Co nanoparticles (NPs) sapphire substrate during pulsed laser-induced dewetting (PLID). NPs produced by PLID wetted the with contact angle near 70°, which is in contrast typical metal thin films exhibiting angles greater than 90°. In addition, nanosca...

This work aimed to demonstrate Cu2O/Al2O3 as a catalyst of the photo-Fenton process in UV and visible spectra. Cu2O nanoparticles were synthesized by laser ablation liquid supported on Al2O3. The catalytic activity resulting solid was assessed mineralization bisphenol A (BPA). studied variables type Al2O3α γ, Cu content (0.5 1%), H2O2 concentration (1, 5, 10 times stoichiometric amount). respon...

The thermal atomic layer etching (ALE) of Al2O3 can be performed using sequential and self-limiting reactions with trimethylaluminum (TMA) and hydrogen fluoride (HF) as the reactants. The atomic layer deposition (ALD) of AlF3 can also be accomplished using the same reactants. This paper examined the competition between Al2O3 ALE and AlF3 ALD using in situ Fourier transform infrared (FTIR) vibra...

We report a quantitative measurement of the pressure effect on melting point elevation of encapsulated nanoparticles without epitaxial interfaces. By means of in situ x-ray diffraction, a substantial melting point elevation of about 15 K in encapsulated Al nanoparticles in Al2O3 shells without epitaxial interfaces was observed. Meanwhile, a pressure buildup of about 0.25 GPa on the Al nanoparti...

Plasma electrolytic oxidation (PEO) was applied using a pulsed unipolar waveformto produce Al2O3−TiO2 composite coatings from sol solutions containing colloidal TiO2 nanoparticles. The were produced by dissolving 1, 3, and 5 g/L of potassium titanyl oxalate (PTO) in silicate solution. Scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, Raman spectroscopy to characte...

Particle morphology and surface properties of metal oxides are topics great importance in the field heterogeneous catalysis. Herein, we have developed a molecular-colloidal coassembly approach combined with an ultrasonic-assisted precipitation method to fabricate [email protected]γ-Al2O3 composites tuneable pore size well-defined octahedral-shape crystal structure. The supramolecular assemblies...

We report the structure and stability of ceria units deposited on the surface of γ-Al2O3 or incorporated in its cavities, as determined by periodic density functional calculations. Ceria species are modeled as CeO2 or Ce2O4 moieties or as a small nanoparticle, Ce13O26, on the (100) and (001) surfaces of a γ-Al2O3 slab. Among the studied structures the incorporation of Ce(4+) ions in cavities of...