Multi-objective optimization of a plate and frame heat exchanger via genetic algorithm

In the present paper, a plate and frame heat exchanger is considered. Multi-objective optimization using genetic algorithm is developed in order to obtain a set of geometric design parameters, which lead to minimum pressure drop and the maximum overall heat transfer coefficient. Vividly, considered objective functions are conflicting and no single solution can satisfy both objectives simultaneously. Multi-objective optimization procedure yields a set of optimal solutions, called Pareto front, each of which is a trade-off between objectives and can be selected by the user, regarding the application and the project’s limits. The presented work takes care of numerous geometric parameters in the presence of logical constraints. A sensitivity analysis is also carried out to study the effects of different geometric parameters on the considered objective functions. Modeling the system and implementing the multi-objective optimization via genetic algorithm has been performed by MATLAB.     

A quantum chemical study of the interactions of uracil as a constituent of ribonucleic acid (RNA) with thiazolidinedione and rhodanine bioactive molecules: an insight into energetic and structural features

In this study, the biologically active configurations composed of Thiazolidinedione–Uracil (TU) and Rhodanine–Uracil (RU) have been fully investigated from the energetic and structural points of view, employing B3LYP and M062X functionals in combination with the different basis sets. Dispersion corrections to the interaction energy using M062X–GD3 and double hybrid density functionals (B2PLYP–GD2, B2PLYP–GD3 and mPW2PLYP–GD2) are also taking into account. The basis set superposition error-corrected interaction energy for hydrogen bonded configurations ranges from ??5.27 to ??13.53 and ??5.25 to ??12.93 kcal/mol for TU and RU complexes respectively as calculated at M062X/6–311++G(df,pd) level. The charge transfer process within all of the TU and RU configurations were analyzed using Natural Bond Orbital (NBO) calculations. The nature of the interactions is analyzed with NBO and Atoms in Molecules (AIM) analysis at M062X/6–311++G(df,pd) and energy decomposition analysis at BP86–D3/TZ2P(ZORA)//M062X/6–311++G(df,pd) level of theory. The results confirm that the nature of the interactions is nearly electrostatic, with a contribution of about 51–56% of the total interaction energy. The orbital interactions (ΔE_orb) for the considered TU and RU complexes have a contribution of about 24–38% of the total interaction energy. Based on the AIM and NBO results, the interactions were defined as electrostatic H-bonds with partially covalent character. In addition, correlation between interaction energies and vibrational frequency changes was investigated.     

Cascade synthesis of fused polycyclic dihydropyridines by Ni–Zn–Fe hydrotalcite (HT) immobilized on silica-coated magnetite as magnetically reusable nanocatalyst

Research on Chemical Intermediates - An efficient ecofriendly approach has been developed for one-pot multicomponent synthesis of fused polycyclic dihydropyridine (DHP) derivatives. Tandem...     

The design of bells with harmonic overtones

Musical bells have had limited application due to the presence of inharmonic partials in the lower part of their acoustic spectra. A series of bells has been designed that contains up to seven partial frequencies in the harmonic series beginning at the fundamental frequency. This was achieved by choosing geometries for finite-element analysis models in which as many purely circumferential bending modes as possible occurred at frequencies below any mode with an axial ring node. The bell models were then fine tuned using gradient projection method shape optimization and the resulting profiles were cast in silicon bronze. A range of bell geometries and timbres is analyzed using psycho-acoustic models and is discussed in relation to European carillon bells.     

A new method for finding the center of gravity of polygons

A direct and easy general method is described for finding the center of gravity of all types of convex and concave polygons such as quadrilaterals, pentagons, hexagons and n-sided polygons.     

ZnBr2 catalyzed domino Knoevenagel-hetero-Diels–Alder reaction: An efficient route to polycyclic thiopyranoindol annulated [3,4-c]quinolone derivatives

Various novel polycyclic thiopyranoindol annulated [3,4-c]quinolone derivatives were synthesized via domino Knoevenagel-hetero-Diels–Alder reactions of indoline-2-thions and novel N-acrylated anthranilaldehydes in refluxing ethanol as a solvent in the presence of 20 mol% ZnBr₂ as a Lewis acid catalyst. All reactions proceed with high yields with excellent regio- and stereoselectivity.     

Synthesis and in vitro antibacterial evaluation of 6-substituted 4-amino-pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidines

Pyrazolo[3,4-d]pyrimidines are one of the most important classes of fused heterocyclic compounds which exhibit a broad range of biological and medicinal properties. They are known as anticancer, antifungal, antibacterial, antiviral and anti-inflammatory agents. In this study, some new 6-substituted 4-amino-pyrazolo[3,4-d]pyrimidine derivatives were prepared via reaction of 5-amino-3-methyl-1-phenyl-1H-pyrazole-4-carbonitrile with various nitriles in the presence of sodium ethoxide as catalyst. The inhibitory properties of synthesized compounds were studied according to CLSI guidelines against some pathogenic bacteria including four gram-positive strains (Streptococcus pyogenes, Staphylococcus aureus, Bacillus cereus and Bacillus subtilis subsp. spizizenii) and three gram-negative strains (Pseudomonas aeruginosa, Shigella flexneri and Salmonella enterica subsp. enterica). The antibacterial effects of all derivatives were compared with those of antibiotics belonging to different classes. The values were reported as inhibition zone diameter (IZD), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The effect of substituents on the biological activity of derivatives was discussed as well. The inhibitory effect of compound 6a, was shown to be the most, with MIC values in the range of 32–4096 μg/mL. Since most of the synthesized compounds were effective against Streptococcus pyogenes and Pseudomonas aeruginosa, they can be considered as inhibitors of these two bacteria.     

Mixed finite difference and Galerkin methods for solving Burgers equations using interpolating scaling functions

The current paper proposes a technique for the numerical solution of Burgers equations. The method is based on finite difference formula combined with the Galerkin method, which uses the interpolating scaling functions. Several test problems are given, and the numerical results are reported to show the accuracy and efficiency of the new algorithm. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and characterization of copper(II) complexes incorporating pyrazolyl-derived N,S-donor bidentate ligands

The novel bidentate N,S-donor anionic ligands [PhNCSIndz]^?, [PhNCSImz]^?, [PhNCSPz^Me3]^?, and [EtNCSPz]^?, where Indz?=?indazole, Imz?=?imidazole, Pz^Me3?=?3,4,5-trimethylpyrazole, and Pz?=?pyrazole, were synthesized and used to prepare Cu(II) complexes of general formula [Cu(N^S)₂]. The ligands were synthesized via direct addition of phenylisothiocyanate or ethylisothiocyanate into THF suspensions of the corresponding sodium-pyrazolate salts. All of the synthesized compounds, including the ligands and the complexes, were characterized by physico-chemical and spectroscopic methods, and crystal structures of [Cu(EtNCSPz)₂] and [Cu(PhNCSPz^Me2)₂] were determined by X-ray diffraction analysis, showing a trans-square planar geometry for [Cu(EtNCSPz)₂] and a distorted tetrahedral geometry for [Cu(PhNCSPz^Me2)₂].