Solid-state synthesis method for the preparation of cobalt doped Ni–Al2O3 mesoporous catalysts for CO2 methanation

In this study, a simple solid-state synthesis method was employed for the preparation of the Ni–Co–Al₂O₃ catalysts with various Co loadings, and the prepared catalysts were used in CO₂ methanation reaction. The results demonstrated that the incorporation of cobalt in nickel-based catalysts enhanced the activity of the catalyst. The results showed that the 15 wt%Ni-12.5 wt%Co–Al₂O₃ sample with a specific surface area of 129.96 m²/g possessed the highest catalytic performance in CO₂ methanation (76.2% CO₂ conversion and 96.39% CH₄ selectivity at 400 °C) and this catalyst presented high stability over 10 h time-on-stream. Also, CO methanation was investigated and the results showed a complete CO conversion at 300 °C.     

Development and Microstructural Characterization of a New Wrought High Entropy Superalloy

Metals and Materials International - In this study, a newly developed γ′ precipitation hardened high entropy superalloy (designated as HES-A1 hereafter) was produced and its...     

Modeling of precipitated asphaltene using the ANFIS approach

Asphaltene precipitation is introduced as a seriously problematic issue in the petroleum reservoirs that causes filling porosity of rocks and reduction of oil production. Hence, estimating the amount of precipitated asphaltene has huge importance in preventing the deposition of asphaltene. The present study was done to estimate the precipitated asphaltene as a function of temperature, dilution ratio, and molecular weight of different n-alkanes using adaptive neuro-fuzzy inference system (ANFIS). Moreover, another new scaling model was also developed to compare with the ANFIS model. In addition, these two developed models have been compared with previously developed correlations. The obtained values of R² for the ANFIS and scaling models were 0.9912 and 0.9862, respectively. These tools are simple to use and can be used as an accurate approximation of the precipitated asphaltene as a function of temperature, dilution ratio, and molecular weight of different n-alkanes.     

The synthesis of poly(vinyl chloride) nanocomposite films containing ZrO2 nanoparticles modified with vitamin B1 with the aim of improving the mechanical,thermal and optical properties

In the present investigation, solution casting method was used for the preparation of nanocomposite (NC) films. At first, the surface of ZrO₂ nanoparticles (NPs) was modified with vitamin B₁ (VB₁) as a bioactive coupling agent to achieve a better dispersion and compatibility of NPs within the poly(vinyl chloride) (PVC) matrix. The grafting of modifier on the surface of ZrO₂ was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA). Finally, the resulting modified ZrO₂ (ZrO₂–VB₁), was used as a nano-filler and incorporated into the PVC matrix to improve its mechanical and thermal properties. These processes were carried out under ultrasonic irradiation conditions, which is an economical and eco-friendly method. The effect of ZrO₂–VB₁ on the properties and morphology of the PVC matrix was characterized by various techniques. Field emission scanning electron microscopy and transmission electron microscopy analyses showed a good dispersion of fillers into the PVC matrix with the average diameter of 37–40 nm. UV–Vis spectroscopy was used to study optical behavior of the obtained NC films. TGA analysis has con?rmed the presence of about 7 wt% VB₁ on the surface of ZrO₂. Also, the data indicated that the thermal and mechanical properties of the NC films were enhanced.     

Solution combustion synthesis of FeCr2O4 powders for pigment applications: Effect of fuel type

Solution combustion synthesis of iron chromite was reported using iron(III) nitrate nonahydrate and chromium(III) nitrate nonahydrate as starting materials, as well as glycine, urea, citric acid, and ethylene glycol as fuels. The influence of fuel type on the structure, molecular, microstructure as well as chromatic properties of samples was investigated. The X-ray diffraction (XRD) patterns showed that unlike themodynamical prediction, glycine fuel led to strongest combustion and consequent highest XRD peak intensities and lower lattice parameters. Moreover, the change of fuel type and mixing of fuels affected XRD data. Fourier transform infrared analysis showed that the band position of Cr–O and Fe–O bonds were shifted to higher frequencies by using of fuels with weaker combustion reactions. In addition, scanning electron micrographs showed that different morphologies of FeCr₂O₄ particles were obtained depending on the fuel type and ratios. Energy-dispersive X-ray spectroscopy analysis of the samples showed that oxygen concentration of samples was less than that of stoichiometric ratio of FeCr₂O₄ due to local reducing atmosphere. Furthermore, chromatic properties of the powders showed that the pigment synthesized with glycine fuel has a better and lighter grayish brown color than the other ones and can be used as a suitable industrial candidate to create a brown color in the ceramic glaze.     

Securing BitTorrent using a new reputation-based trust management system

Nowadays, BitTorrent as a means of sharing files has become highly popular among internet users. However, due to the open nature of BitTorrent protocol and lack of any security mechanism, number of attacks against BitTorrent has significantly increased. Sybil, Collusion, Lying-Piece, Fake-Block, and Chatty-Peer are attack types which have been considered in this paper to secure BitTorrent against them. These attacks can decrease the download performance of BitTorrent clients considerably. In this paper a new reputation based trust management system to cover aforementioned attack types is presented. The proposed approach calculates a local score at peers and a global score at the tracker for each peer. First, peers are sorted according to their cumulative score at the tracker and then top 10 % of these peers are used to determine other peers global score. These local and global scores are used to find attackers. In addition, a novel formula has been utilized to calculate peers local score. Using the global score concept makes our mechanism robust and swift to detect collusion attack which has not been considered in most of similar previous works. In order to evaluate the effectiveness of the proposed system, several simulation and real experiments in the Emulab testbed were performed. The outcomes indicate that our method is highly effective in detection of rogue peers and Free-Riders; moreover, performance of honest peers has significantly improved.     

Major alkaloids of Glaucium flavum Grantz, population Ghom

Glaucium flavum Grantz, population Ghom, contains 1.24% dicentrine, 0.89% bulbocapnine, and 0.05% salutaridine in dry aerial parts and root of the flowering plant. These alkaloids were detected for the first time in the Glaucium genus.