Macrocycles as components of gas-chromatographic phases

The use of crown compounds (18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6, benzo-15-crown-5, dibenzo-24-crown-8, 4,13-diaza-18-crown-6,4,13-dibenzyl-diaza-18-crown-6, and cryptand [2.2.2]) as components of stationary phases in the determination of organic compounds by gas chromatography is studied. The polarity, selectivity, efficiency, and working temperature ranges of stationary phases based on crown ethers and cryptand as well as conventional stationary phases for gas chromatography are compared. The influence of the type and number of heteroatoms, the conformational lability of the cavity, and the presence of substituents on the polarity and selectivity of the stationary phases under study is revealed. Preferable types of interactions of stationary phases containing crown compounds with organic compounds of different classes are discussed. It is concluded that phases of the mixed type based on crown ethers are promising for improving the selectivity and efficiency of gas-chromatographic separation     

Synthesis,anticancer screening,and in silico ADME prediction of novel 2-pyridones as Pim inhibitors

A novel series of 26 substituted N-(2-ethylphenyl)-2-oxo-pyridine-3-carbonitriles have been designed and synthesized via one-pot synthesis of various aromatic aldehydes, different aromatic acetophenones, and 2-cyano-N-(2-ethylphenyl)acetamide 1 . Moreover, cytotoxicity of the target compounds was evaluated by NCI, which selected 14 compounds for one-dose screening. Among them, compound 21 was selected for five-dose screening, which confirmed its potency against most of cancer cell lines. This compound elicited selectivity profile against human cell line WI-38. Cell cycle analysis was carried out, revealed that compound 21 is an apoptosis inducer causing cell cycle arrest at G2/M. Further exploration on the mode of action by evaluating its effect against Pim-1, Pim-2, and Pim-3 demonstrated its inhibitory effect on Pim-1 and Pim-3 rather than Pim-2. Molecular docking showed that compound 21 binds with high affinity to the active site of Pim-1 enzyme through three hydrogen bonds and two arene-H bonds.     

Chiral Lithium Amido Aryl Zincates: Simple and Efficient Chemo‐ and Enantio‐Selective Aryl Transfer Reagents

An enantioselective aryl transfer is promoted using chiral tricoordinated lithium amido aryl zincates that are easily accessible reagents and whose chiral appendage is simply recovered for reuse. The arylation reaction is run in good yields (60 % average on twenty substrates) and high enantiomeric excesses (95 % ee average). This occurs whatever the ortho, meta, or para substituent borne by the substrate and a complete chemoselectivity is observed with respect to the aldehyde function. Sensitive groups such as nitriles, esters, ketones, and enolisable substrates resist to the action of the ate reagent, warranting a large scope to this methodology.     

Solvent Effects on the Kinetics of Amide Bond Cleavage in p-Chloro and p-Bromo Oxazolinones in Acetonitrile–Water Mixtures

The kinetics of amide bond cleavage in p-chloro and p-bromo oxazolinone have been studied using triethylamine as a base catalyst under pseudo-first order conditions, in the temperature range (303.15?C333.15?K). The reaction rate was measured spectrophotometrically over a range of acetonitrile?Cwater mixed solvent (30?C70?%, v/v) compositions. The reaction rate was found to be faster for p-Cl than for p-Br oxazolinone. The thermodynamic parameters of activation were calculated: ?G* increased gradually as the mole fraction of the cosolvent increased due to quasi-mirror image compensation of ?H* and ?S* (entropy?Centhalpy compensation). The isokinetic temperature indicates that the reaction is enthalpy controlled. The reactivity was analyzed in the light of various simple and multiple regression equations using the Kamlet?CTaft solvatochromic parameters.     

Interrelated functionalities of hierarchically CNT/CeO2/Pt nanostructured layers: synthesis, characterization, and electroactivity

We present a free-standing catalyst layer comprising current collector/CNTs (catalyst support)/CeO(2)/Pt (catalyst) nanostructured layers, each layer constructed upon the one below it. FESEM and TEM showed that a CeO(2) layer has a fluffy morphology recalling the texture of cotton, whereas Pt nanoparticles assemble into cauliflower or broccoli-like arrangement. New insights have been gained into the effect of CeO(2) on the structural properties of the beneath CNTs layer and on the above Pt layer. First, by means of Raman analysis, it was found that interaction of CeO(2) with CNTs induced a decrease in the crystallinity of the latter. Second, by TEM and XPS analyses, it was observed that the size of Pt nanoparticles in the CNT/CeO(2)/Pt structure was inferior to that in the CNT/Pt, implying that CeO(2) influenced the dispersion quality of Pt nanoparticles. For the first time, it is observed that CeO(2) supported CNTs undergo oxidation/reduction reactions at low potentials in the ethanol electrolyte. The electrochemical analysis showed that entities produced from those redox processes are surface adsorbed/desorbed species most likely hydroxides. This unexpected electroactivity is due to the beneath CNTs that boosted the conductivity of CeO(2). Such improved conductivity of CeO(2) has fostered the electron-transfer kinetics of ethanol at Pt as demonstrated by the decreased overpotential required to oxidize ethanol and by the specific mass activity, which was greater than that of CNT/Pt.     

On steady motions of a rigid body bearing three-degree-of-freedom control momentum gyroscopes and their stability

Equations of motion are obtained for a rigid body bearing N three-degree-of-freedom control momentum gyroscopes in gimbals and the entire set of steady motions in a homogeneous external field is determined. The steady motion dependence on the magnitude of the system angular momentum is studied and a detailed analysis of the secular stability is performed.     

Separation of representations with quadratic overgroups

Any unitary irreducible representation π of a Lie group G defines a moment set Iπ, subset of the dual g^? of the Lie algebra of G. Unfortunately, Iπ does not characterize π. If G is exponential, there exists an overgroup G⁺ of G, built using real-analytic functions on g^?, and extensions π⁺ of any generic representation π to G⁺ such that Iπ⁺ characterizes π.In this paper, we prove that, for many different classes of group G, G admits a quadratic overgroup: such an overgroup is built with the only use of linear and quadratic functions.     

The asymptotic properties of the motions of satellites in a central field due to internal dissipation

A satellite in the form of a system of bodies that does not have the property of a gyrostat in the general case is considered. An algorithm for determining all the equilibrium configurations of the system that correspond to steady motions in a central gravitational field and an algorithm for analysing their stability are given. A method based on Routh's first theorem is used to investigate the asymptotic stability of the steady motions in the unconstrained problem. Three effects caused by internal dissipation are established in a model example: stabilization of the satellites in a neighbourhood of rotations about a normal to the orbital plane, which is codirectional with the axis of the largest moment of inertia, evolution of elliptic orbits into circular orbits, and capture of the satellites in resonant oscillatory modes of motion.     

The properties of the steady motions of a body carrying a system of two-degree-of-freedom powered gyroscopes

The steady motions of a rigid body carrying several two-degree-of-freedom powered gyroscopes in a uniform external field are investigated. It is shown that when the installation scheme of the gyroscopes in the carrying body is collinear, the problem of determining the steady motions of the system and analysing their secular stability reduces for the most part to the previously solved, similar problem for a system with one gyroscope. It is established that when there is dissipation in the axes of the gyroscope frames, the system tends asymptotically to a state of rest if the absolute value of the total angular momentum of the system lies in the segment of possible absolute values of the angular momentum of the gyroscope rotors. The results of an analysis of the steady motions of a system carrying two gyroscopes with a non-collinear installation scheme are presented.