On the development of Taylor vortices in a vertical annulus with a heated rotating inner cylinder

A numerical study has been conducted to determine the heat transfer characteristics and flow patterns which develop around a rotating, heated vertical cylinder enclosed within a stationary concentric cylinder. A tall annulus (aspect ratio of 10) with fixed, adiabatic horizontal end-plates and a radius ratio of 0·5 has been considered. Furthermore, the effect that the introduction of buoyancy forces by heating the inner cylinder has on the development of the Taylor vortex flow is examined. It is observed that the formation of the Taylor vortices is delayed until the rotational parameter σ = Gr/Re² has a value below unity for any given Reynolds number Re which is above the critical value Re_crit for the formation of Taylor vortices in an isothermal flow. Also, the Taylor cells first appear at the top of the annulus. As σ is gradually decreased below unity, bifurcations to other states are observed. The final structure of the secondary flow is noticeably distorted in the mixed-convection mode, with the size of the Taylor cells varying greatly along the height of the annulus. This distortion diminishes as σ is further decreased, until the isothermal flow pattern is nearly recovered below σ = 0·01.     

Synthesis and application of rhodium complexes of asymmetric water-soluble diphosphine derived from 2-[(diphenylphosphino)methyl]-4-(diphenylphosphino)-pyrrolidine

Optical yields of up to 60% are obtained in the hydrogenation in water of prochiral compounds in the presence of rhodium complexes of asymmetric water-soluble diphosphines derived from 2-[(diphenylphosphino)methyl]-4-(diphenylphosphino)pyrrolidine.     

Synthesis and Molecular Docking Studies of Novel 2‐Phenyl‐4‐Substituted Oxazole Derivatives as Potential Anti‐cancer Agents

A novel series of 2,4‐disubstituted oxazole derivatives were synthesized, screened for their anti‐tumor activity against three cell lines MCF‐ 7 , TK‐10, and UACC‐62. Molecular docking study was carried out against epidermal growth factor receptor. A new series of 2‐phenyl‐4‐substituted oxazole derivatives were synthesized. A series of chiral α‐amino acid derivatives 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 were synthesized by coupling various l ‐acylated amino acid azide 3. The synthesized compounds were tested for their in vitro antitumor activity against MCF‐7, TK‐10, and UACC‐62 cell lines. Compound 6 exhibited the strongest inhibitory activity against TK cell lines, while compound 12 showed the highest activity against MCF‐7 cell lines. Compound 14 was the most active against UACC‐62 cell lines. Furthermore, a molecular docking study of the most active compounds was carried out using epidermal growth factor receptor X‐ray 3D structure (protein data bank ID 1 M17). Docking results revealed that compound 6 showed the highest binding energy of ΔG = ?78.17 Kcal/mol.     

A mapping technique for better solution exploration: NSGA-II adaptation

A mapping method (MaM) for a better solution space exploration adapted to NSGA-II method is presented. The Mapping technique divides the solution space into several zones using a Hamming distance to a reference solution. We present a bijective mapping function from the search space to the binary representation space of solutions. For each zone, a mapping metric is used to evaluate the solution space exploration. According to this evaluation, a local search is performed. The mapping is adapted to the well known non-dominated sorting genetic algorithm-II (NSGA-II) method applied to solve the flexible job shop problem (FJSP) case. We present the comparison between the hybridization using the local search for the non-dominated solutions and the hybridization using the mapping metrics. The multi-objective metrics show the efficiency of mapping adaptation in terms of convergence and diversity.     

Persistence of quantum correlations in a XY spin-chain environment

Quantum correlations in a physical system are usually degraded whenever there is aninteraction with the environment. Here we consider the action of a XY spin-chain interactingwith a system of two qubits. Results are surprising for particular families of statessince their evolution does not destroy the presence of either entanglement or nonlocality,that is, those correlations persist for any possible configuration of theenvironment. In addition, we unveil the form of those states which, although being mixed,their entanglement implies nonlocality and vice versa. This finding constitutes anextension of the well-known Gisin Theorem for pure states of two qubits.The ensuing form will enable us to find the evolved entanglement and nonlocality in ananalytical fashion.     

Back titration with mercuric nitrate in alkaline medium analysis of tertiary mixtures of mercury(II) with some other metals

Summary Tertiary mixtures each containing mercury(II) were analysed by simple procedures involving combination between the recent method of back titration with mercuric nitrate in alkaline medium, and the volumetric methods which make use of masking agents as cyanide. The content of mercury(II) in most mixtures is determined potentiometrically with potassium iodide using the silver amalgam as indicator electrode. End points are attended with fair accuracy within 0.02 ml titrant and with reasonable jumps from 60 to 90 mv per 0.1 ml of mercuric nitrate solution or from 170 to 200 mv per 0.1 ml of potassium iodide solution.     

Ionic‐Liquid‐Based Acidic Aqueous Biphasic Systems for Simultaneous Leaching and Extraction of Metallic Ions

The first instance of an acidic aqueous biphasic system (AcABS) based on tributyltetradecyl phosphonium chloride ([P₄₄₄₁₄][Cl]) and an acid is here reported. This AcABS exhibits pronounced thermomorphic behavior and is shown to be applicable to the extraction of metal ions from concentrated acidic solutions. Metal ions such as cobalt(II), iron(III), platinum(IV) and nickel(II) are found to partition preferentially to one of the phases of the acidic aqueous biphasic system and it is here shown that it successfully allows the difficult separation of Co^II from Ni^II, here studied at 24 and 50 °C.     

Synthesis and conformational behaviour of 1,9,17-triaza[2.2.2]metacyclophane-2, 10, 18-trione derivatives

The 1,9,17-triaza[2.2.2]metacyclophane-2, 10, 18-trione derivatives ($\text{1}$) – ($\text{3}$) have been synthesised. X-Ray crystallography shows that the 1,9,17-trimethyl derivative ($\text{3}$) adopts a Crown conformation ($\text{11}$) in the solid state. Dynamic n.m.r. spectroscopy indicates that both the 1,9-dimethyl-17-benzyl- ($\text{2}$) and 1,9,17-trimethyl- ($\text{3}$) derivatives exist as interconverting mixtures of Crown ($\text{11}$) and Saddle ($\text{12}$) conformations with the former predominating at equilibrium in solution.     

Acetylenic ketones. VII—Structural analyses by mass spectrometry of the products obtained from the reaction of acetylenic ketones with nucleophilic sulphur compounds

The mass spectra of β-hydroxy-α-thiobenzoylstyrene derivatives and (E, Z)- or (E, E)-β,β-di(α-aroylstyryl)sulphides as well as β,β′di(α-aroylstyryl)disulphides are discussed. The fragmentation patterns support their proposed structure and configuration.     

Reaction of α,β-unsaturated ketones with guanidine. Substituent effects on the protonation constants of 2-amino-4,6-diarylpyrimidines

1,3-Diaryl-2-propen-1-ones, I, reacted with guanidine hydrochloride (II) in the presence of 3 moles of sodium hydroxide to give the corresponding 2-amino-4,6-diarylpyrimidines, III. The structure and configuration of the products are based on chemical and spectroscopic evidence. The protonation constants of these compounds (series A and series B) have been determined in 50 volume percent ethanol-water medium. Excellent linear correlations are obtained when pK_a values of the two series of 2-amino-4,6-diarylpyrimidines, IIIa-j and IIIk-r, are plotted against the substituent constant, ^σx, and the polar substituent constant, ^σ* xC₆H₄, for substituted phenyl groups. The pK_a values have also been correlated with the extended Hammett equation. The correlation follows the equations: Series A; pK_a = 3.273 - 0.820σI,X - 0.662σR,X Series B; pK_a = 3.169 - 0.424σI,X - 0.137σR,X