Hybrid routing scheme using imperialist competitive algorithm and RBF neural networks for VANETs

Wireless Networks - Vehicular ad hoc network (VANET), a special type of mobile ad-hoc networks (MANETs), is characterized by a very high mobility. Due to the dynamic nature of vehicle nodes and...     

A Novel 3-D Nanoporous Ce(III) Metal-Organic Framework with Terephthalic Acid; Thermal,Topology, Porosity and Structural Studies

This study describes the synthesis, crystal structure, porosity, and thermal stability of a new three-dimensional nano-porous metal-organic framework, [Ce₂(tp)₃(DMF)₂(DMSO)₂]_n, 1, (H₂tp = terephthalic acid, DMF = dimethyl formamid, DMSO = dimethyl sulfoxide). Compound 1 was synthesized by the solvothermal reaction of Ce(NO₃)₃·6H₂O and H₂tp and was then characterized by single-crystal X-ray diffraction and infrared spectroscopy. Structural analysis of 1 showed that Ce(III) ion has coordination number nine in a distorted mono-capped square anti-prismatic geometry. Gas sorption studies revealed a relatively reversible type-I isotherm characteristic of a porous material with surface area, pore volume, and average pore size of 179.4 m² g^?1, 0.73 cm³ g^?1, and 3.8 Å, respectively.     

Size-controlled synthesis of ZnO nanocrystals from diethylzinc and donor-functionalized alcohols

Nanocrystals of zinc oxide (ZnO) were prepared from diethylzinc and donor-functionalized alcohols, 2-methoxyethanol, 2-ethoxyethanol, and 2-methoxyethoxyethanol by sol-gel processing. The nanocrystals were prepared at room temperature and characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). Crystal sizes were controlled by the type of utilized donor-functionalized alcohol in which decreased by an increase of the chain length and type of the donor-functionalized alcohol from 16 to 27 nm. The HRTEM and SAED results revealed that the degree of crystallinity decreases with increasing donor-functionalized alcohol chain length. The particle size of the ZnO powders demonstrated high tolerance to heat treatment and grow up to approximately 65 to 80 nm upon calcination at 1000 °C.     

A novel porous nanocomposite of aminated silica MCM‐41 and nylon‐6: Isotherm,kinetic, and thermodynamic studies on adsorption of Cu(II) and Cd(II)

Porous amine‐modified MCM‐41/Nylon‐6 nanocomposite (NH₂‐MCM‐41/NY6 NC) was synthesized by a facile solution casting protocol, which was used as an effective adsorbent for the removal of Cu(II) and Cd(II) from aqueous media. The physicochemical properties of NH₂‐MCM‐41/NY6 NC were studied by scanning and transmission electron microscopies, thermogravimetric analysis, etc. The influence of pH, adsorbent dose, contact time and initial concentration on adsorption performance were investigated in detail. Kinetic and isotherm parameters were evaluated and the data fitted well to the pseudo‐second order and Freundlich isotherm model, respectively. The maximum adsorption capacities of Cu(II) and Cd(II) were about 35.84 and 27.5 mg·g^?1, respectively. The K_d of NH₂‐MCM‐41/NY6 NC for Cu(II) (> ) and Cd(II) (> ) ions uptake in aqueous solution, showed very good values. Thermodynamic parameters suggest that the adsorption is a spontaneous process with an endothermic nature. According to the results obtained, we conclude that this novel porous NH₂‐MCM‐41/NY6 NC could be used for the removal of heavy metal ions from an aqueous solution. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45383.     

Organo-Modification of Mesoporous SBA-15 with Chiral Diacid and its Utilization for the Preparation of L-Phenylalanine-Based Poly(amide-imide) Nanocomposites

In this study ultrasonic irradiation has been proposed for organo-modification of SBA-15 with N,N′-(pyromellitoyl)-bis-L-phenylalanine. Chiral poly(amide-imide) (PAI) was synthesized by the direct polymerization of L-chiral diacid and 4,4-diaminodiphenyle sulfone in molten tetrabutylammonium bromide. Different nanocomposites (NCs) of modified SBA-15 and chiral PAI were synthesized by solution intercalation method under ultrasonic irradiation. The structures and morphology of the hybrids were investigated by different techniques. The NCs showed an improvement in the thermal properties in comparison with the neat PAI. Transmission electron microscopy images show well-ordered hexagonal arrays of mesopores SBA and the average distances between neighboring pores is around 3–5 nm.     

The Effect of Nb and Ti on Structure and Mechanical Properties of 12Ni-25Cr-0.4C Austenitic Heat-Resistant Steel after Aging at 900 °C for 1000 h

Austenitic heat-resistant steels are particularly suitable for applications where service conditions comprise high temperature. The demand for better performance has motivated developments in these steels. In this work, Ti and Nb were added to austenitic heat-resistant steels, Fe-12Ni-25Cr-0.4C, wt.% simultaneously. Microstructural changes were studied via scanning electron microscopy equipped with energy dispersive spectrum (EDS), optical microscopy, and x-ray diffraction (XRD) in as-cast condition and after aging in 900 °C for 1000 h. Mechanical properties were measured using tensile tests, impact energy, and Vickers hardness. It was observed that by formation of NbC and TiC, the level of fragmentation of the chromium carbides increased, as a positive aspect for mechanical properties. XRD and EDS results show increasing the amount of Ti can inhibit G-phase transformation.     

Production of High-Strength Al/Al2O3/WC Composite by Accumulative Roll Bonding

In this study, Al/Al₂O₃/WC composites were fabricated via the accumulative roll bonding (ARB) process. Furthermore, the microstructure evolution, mechanical properties, and deformation texture of the composite samples were reported. The results illustrated that when the number of cycles was increased, the distribution of particles in the aluminum matrix improved, and the particles became finer. The microstructure of the fabricated composites after eight cycles of the ARB process showed an excellent distribution of reinforcement particles in the aluminum matrix. Elongated ultrafine grains were formed in the ARB-processed specimens of the Al/Al₂O₃/WC composite. It was observed that as the strain increased with the number of cycles, the tensile strength, microhardness, and elongation of produced composites increased as well. The results indicated that after ARB process, the overall texture intensity increases and a different-strong texture develops. The main textural component is the Rotated Cube component.