Low-temperature synthesis of mesoporous nanocrystalline magnesium aluminate (MgAl2O4) spinel with high surface area using a novel modified sol-gel method

A simple, template-free and scalable modified sol-gel route was developed for the synthesis of mesoporous flake-like magnesium aluminate spinel (MgAl₂O₄) at low temperature (700 °C) with high surface area (281 m² g^?1). The obtained spinel materials were characterized by means of physicochemical techniques including X-ray diffraction, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and N₂ adsorption-desorption analysis. The propylene oxide was used as gelation and pore forming agent in the sol-gel process. Different morphologies and sizes of flake were generated by the varied synthesis conditions. The result materials reveal that the textural properties of the MgAl₂O₄ product are strongly associated with the nature and amount of addictive solvent and calcination temperatures. It shows that the BET surface area decrease as the increase of calcination temperature and the optimal temperature of 700 °C result in the pure phase of MgAl₂O₄ spinel. This synthesis strategy offers a feasible approach for scalable fabrication of mixed metal oxides for various catalytic reactions or catalyst supports due to the large surface area.     

Interaction of hydrogen sulfide with the pristine and B&N-doped beryllium oxide nanotube: DFT study

ABSTRACT

In this study, hydrogen sulfide interaction with pristine, B-, N-, and B&N atom-doped beryllium oxide nanotube (BeONTs) is investigated by the density functional theory (DFT) method. At the first step, we considered different configuration models for the adsorption of H₂S on the surface of nanotube and then we selected 12 stable models for this study. The structures of all selected models are optimized and the quantum properties, thermodynamic parameters, natural bond orbitals (NBO), reduced density gradient (RDG), molecular electrostatic potential (MEP), and atom in molecule (AIM) parameters are calculated at the cam–B3LYP level of theory with 6–31G (d) base set. The obtained E_ads for the exterior surface of nanotube is exothermic and is in the range –3.15 to –28.34?Kcal mol^–1, and that for the interior surface is endothermic and is in the range 19.17 to 27.17?kcal mol^–1. The gap energy for pure, B-doped, N-doped, and B&N-doped BeONTs is 10.11, 10.03 (α spin), 10.13 (α spin), and 9.35?eV, respectively. The results of thermodynamic parameters, such as ΔG and ΔH values for the adsorption of H₂S, on the surface of B-doped BeONTs are more negative than other models and favorable in thermodynamic approach. The NBO, MEP, NMR, and HOMO–LUMO results confirm that the electron charge transfer occurs from H₂S molecule toward BeONTs, as a result the bonding type of H₂S?…?BeONTs is weak ionic.     

Application of Amine Modified Magnetic Nanoparticles as an Efficient and Reusable Nanofluid for Removal of Ba2+ in High Saline Waters

Silicon - This study describes an investigation on the application of functionalized nanoparticles used as a sorbent for extraction and removal of barium ions from high saline waters. Magnetic...     

Amygdalin Contents of Oil and Meal from Wild Almond: Effect of Different Heat Pretreatment and Extraction Methods

The effects of different heat treatment methods on the extraction yield of oil and the amygdalin contents of the wild almond meal and oil were investigated. When using hexane as a solvent for the extraction, oil yield and amygdalin contents of the extracted oils increased by increasing the applied temperature as the pretreatment (46.1–51.6%, w/w, for oil yield and 26–49 mg/100 mL oil for the amygdalin content). When using mechanical oil extraction, hot-press resulted in higher oil yield (23.2%) than did the cold-press (15.6%) but the amygdalin levels of the extracted oils were not significantly different (12.8–12.9 mg/100 mL oil). Autoclaving ground wild almond and hot-press resulted in a significant increase in the peroxide and acid values of the oils. Investigation of fatty acid profiles of different samples showed that heat treatment and extraction method in this study did not impact the fatty acid profiles of the extracted oils.     

Resource Management in a Peer to Peer Cloud Network for IoT

Wireless Personal Communications - Software-Defined Internet of Things (SDIoT) is defined as merging heterogeneous objects in a form of interaction among physical and virtual entities. Large scale...     

Reduction of carbon dioxide to methanol on the surface of adenine functionalized reduced graphene oxide at a low potential

In this study, the surface of reduced graphene oxide (rGO) was modified with adenine via diazonium reaction. Then, to prepare Pt@Adenine-rGO, Pt was deposited on the surface of adenine-rGO, using cyclic voltammetry in the range of ?0.30 to +1.30 V at a scan rate of 100 mV s^?1 in a solution containing Pt salt. Afterward, it was characterized by various techniques such as scanning electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. Electrochemical studies showed the efficient electrocatalytic behavior of Pt@Adenine-rGO for the reduction of CO₂ to methanol at ?0.30 V. The products formed on the surface of Pt@Adenine-rGO were monitored using different techniques including Raman spectroscopy, gas chromatography, gas chromatography-mass spectrometry, and ¹³C NMR spectroscopy. Our findings indicated that methanol with a reasonably high Faradaic efficiency up to 85% and a current density of 0.5 mA cm^?2 as the main product of CO₂ reduction on the surface of Pt@Adenine-rGO.     

Compact tunable tri-band bandpass filter using varactor diodes for wireless fidelity,wireless local area network,and worldwide interoperability for microwaves access applications

The purpose of this paper is to present a tri-band bandpass filter (BPF) with compact structure. This filter consists of 50 Ω transmission line, varactor diode, positive-intrinsic-negative (PIN) diode, symmetrical square-shaped half-loop resonator pair, and three pairs of rectangular half circle that a T-stub is placed in it. By using the add PIN and varactor diodes in the proposed structure, it is possible to connect and disconnect each band, and change the central frequency up to 400 MHz. In addition, there is a situation to disconnect and connect all three bands simultaneously and asynchronously (unconditionally). This filter contains a low ripple value in all three bands. In this regard, the maximum ripple value does not exceed 0.3 dB and rejection is greater than 25 dB in total stop-band. An experimental tri-band BPF has been developed for wireless fidelity, wireless local area network, and worldwide interoperability for microwaves access applications. The measured results are properly accommodated with simulated results.     

Scalable video traffic offloading for streaming services in 5G HetNets

Multimedia Tools and Applications - In this paper, by combining scalable video coding (SVC) and traffic offloading, we propose a scalable video traffic offloading (SVO) approach to provide video...