Adsorption of H2S on carbonaceous materials of different dimensionality

The effect of the dimension of carbonaceous systems, from two to zero, on the adsorption strength of H₂S is investigated by density functional theory based methods. To this end, a carbon nanocone (CNC), a (3, 3) carbon nanotube ((3, 3)-CNT), and graphene (G) are chosen as models for zero-, one- and two-dimensional systems, respectively. Pristine G and CNC have low tendency to adsorb H₂S but on the (3, 3)-CNT the molecule adsorbs dissociatively and deforms the surface. The effect of doping the surface of these materials with Ti has also been investigated. The presence of Ti modifies H₂S adsorption capability to the point that it is chemically adsorbed on the three decorated surfaces although H₂S adsorption on Ti decorated graphene appears to be different from two other doped surfaces. Only in this case, the H₂S molecule dissociates and releases hydrogen atoms which form H₂ molecule. The resulting H₂ molecule is physisorbed on the Ti-decorated graphene surface and the S atom adsorbs directly on the Ti atom. The density of states of pristine, Ti decorated and H₂S adsorbed nanostructures demonstrate that the systems change their conductivity and magnetic properties.     

Geochemical characteristics of upper Jurassic carbonate reservoir bitumen in the Eastern Kopeh-Dagh,NE Iran

Geochemical characteristics of solid bitumen in Upper Jurassic carbonate reservoir are investigated. Aromatic maturity parameters indicate peak to late oil window level of maturity for the bitumen samples. Regular sterane distributions, conical variable (CV), plots of δ¹³C_Sat versus δ¹³C_Aro and Pr/nC₁₇ against Ph/n_C18, predominance of C₂₃ tricyclic terpane, ratios of steranes/hopanes and C₂₃/C₂₁ tricyclic terpane indicate charging from clastic-rich anoxic marine source rocks. Ratios of C₂₉/C₃₀ hopane, Ts/Ts+ Tm, C₂₄ tetracyclic terpane/C_20-26 tricyclic terpanes and plot of C₂₂/C₂₁ versus C₂₄/C₂₃ tricyclic terpanes show influences of carbonate/marl facies. All these would throw crucial guiding light on the interpretation of the future exploration.     

Query optimization mechanisms in the cloud environments: A systematic study

The goal of a query optimizer is to provide an optimal Query Execution Plan (QEP) by comparing alternative query plans. In a distributed database system over cloud environment, the relations required by a query plan may be stored at multiple sites. This leads to an exponential increase in the number of possible equivalent plan alternatives to find an optimal QEP. Although it is not computationally reasonable to explore exhaustively all possible plans in such large search space. Although query optimization mechanisms are important in the cloud environments, to the best of our knowledge, there exists no complete and systematic review on investigating these issues. Therefore, in this paper, four categories to study these mechanisms are considered which are search‐based, machine learning‐based, schema‐based, and security‐based mechanisms. Also, this paper represents the advantages and disadvantages of the selected query optimization techniques and investigates the metrics of their techniques. Finally, the important challenges of these techniques are reviewed to develop more efficient query optimization techniques in the future.     

Instrumental shade sorting of coloured fabrics using genetic algorithm and particle swarm optimisation

In the present research by combination of Clemson Colour Clustering (CCC) instrumental shade sorting method and two metaheuristic algorithms, a genetic algorithm (GA) and a particle swarm optimisation (PSO), two new shade sorting methods, called CCCGA and CCCPSO were proposed. Then these proposed methods were applied on 16 well-prepered colour sets made of coloured fabrics and their results were compared using some important performance evaluation factors. The results of the methods were also compared with conventional CCC shade sorting method and a method based on CCC combined with k-means technique (CCCk). The results obtained from various shade sorting methods showed that the CCCGA and CCCPSO methods successfully sorted the coloured fabrics with high efficiency, and their results slightly outperformed the results of the CCC method.     

Synthesis and Characterization of Polycarbonate/TiO2 Ultrafiltration Membranes: Critical Flux Determination

A novel polycarbonate (PC) membrane was modified with titanium dioxide via nonsolvent-induced phase separation method to improve its hydrophilicity and antifouling properties in a submerged membrane system for the removal of humic acid (HA) both with and without polyaluminum chloride (PAC) coagulant. The effect of TiO₂ additive on the morphology and performance of the nanocomposite membranes was studied by atomic force microscopy, field emission scanning electron microscopy, energy dispersive X-ray, mechanical properties, water contact angle, porosity, pure water flux, rejection tests, and antifouling parameters. The obtained results revealed that a higher critical flux was achieved by the PC/TiO₂ nanocomposite membrane. The flux recovery ratio of the neat PC membrane increased with the addition of TiO₂ nanoparticles and without PAC coagulant. HA removal for the PC nanocomposite membrane was higher than that of the neat PC membrane with and without PAC coagulant.     

Polyionene/Br3 Grafted on Magnetic Nanoparticles as an Efficient and Eco-Friendly Catalyst for the Metal Free Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones/Thiones

Silicon - A novel polyionene modified magnetic nanoparticle with a core-shell-shell structure was developed for utilization as a heterogeneous catalyst in the metal free synthesis of...     

Synthesis and Antimicrobial Evaluation of Some Novel Thiazole,Pyridone, Pyrazole,Chromene, Hydrazone Derivatives Bearing a Biologically Active Sulfonamide Moiety

This study aimed for the synthesis of new heterocyclic compounds incorporating sulfamoyl moiety suitable for use as antimicrobial agents via a versatile, readily accessible N-[4-(aminosulfonyl)phenyl]-2-cyanoacetamide (3). The 2-pyridone derivatives were obtained via reaction of cyanoacetamide with acetylacetone or arylidenes malononitrile. Cycloaddition reaction of cyanoacetamide with salicyaldehyde furnished chromene derivatives. Diazotization of 3 with the desired diazonium chloride gave the hydrazone derivatives 13a–e. Also, the reactivity of the hydrazone towards hydrazine hydrate to give Pyrazole derivatives was studied. In addition, treatment of 3 with elemental sulfur and phenyl isothiocyanate or malononitrile furnished thiazole and thiophene derivatives respectively. Reaction of 3 with phenyl isothiocyanate and KOH in DMF afforded the intermediate salt 17 which reacted in situ with 3-(2-bromoacetyl)-2H-chromen-2-one and methyl iodide afforded the thiazole and ketene N,S-acetal derivatives respectively. Finally, reaction of 3 with carbon disulfide and 1,3-dibromopropane afforded the N-[4-(aminosulfonyl) phenyl]-2-cyano-2-(1,3-dithian-2-ylidene)acetamide product 22. All newly synthesized compounds were elucidated by considering the data of both elemental and spectral analysis. The compounds were evaluated for both their in vitro antibacterial and antifungal activities and showed promising results.     

Design aspect of a novel L-shaped pulsed column for liquid–liquid extraction applications: Energy consumption and the characteristics velocity concept

This article deals with the evaluation of the consumption of energy for a steady state solvent extraction in a novel L-shaped pulsed sieve-plate column,which is highly required for design and optimization of the periodic flow processes for industrial applications.In this regard,a comprehensive evaluation on the energy consumption in case of a pulsed flow for three different chemical systems is conducted and besides the influence of pulsation intensity,the effect of geometrical parameters including the plate spacing and the plate free area is investigated as well.Moreover,the concept ofcharacteristic velocity models at flooding points is evaluated with respect to the variation of pressure drop along the column at different operational conditions.