Complexation diastereoselective d''alcools benzyliques par le chrome hexacarbonyle. Difference de reactivite des diastereoisomeres en milieu acide.

Reaction of ortho alkyl or alkoxy phenyl carbinol with Cr(CO)₆ affords arene chromium tricarbonyl complexes with 38 to 86% of diastereoisomeric excess. The behavior of the two diastereoisomers shows a striking difference. Equimolar mixture of (RR,SS) and (RS,SR) diastereoisomers treated with concentrated sulfuric acid and methanol gives (RS,SR) ether while (RR,SS) alcool remains unchanged.     

Application of <Emphasis Type="Italic">G</Emphasis>′/<Emphasis Type="Italic">G</Emphasis>-expansion method to Kuramoto-Sivashinsky equation

This paper obtains the solutions of the Kuramoto-Sivashinsky equation. The G′/G method is used to carry out the integration of this equation. Subsequently, its special case, will be integrated and topological 1-soliton solution will be obtained by the soliton ansatz method. The restrictions on the parameters and exponents are also identified.     

Optimal design and characterization of superparamagnetic iron oxide nanoparticles coated with polyvinyl alcohol for targeted delivery and imaging

Superparamagnetic iron oxide nanoparticles (SPION) with narrow size distribution and stabilized by polyvinyl alcohol (PVA) were synthesized. The particles were prepared by a coprecipitation technique using ferric and ferrous salts with a molar Fe3+/Fe2+ ratio of 2. Using a design of experiments (DOE) approach, the effect of different synthesis parameters (stirring rate and base molarity) on the structure, morphology, saturation magnetization, purity, size, and size distribution of the synthesized magnetite nanoparticles was studied by various analysis techniques including X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC) measurements, vibrating-sample magnetometer (VSM), transmission electron microscopy (TEM), UV-visible, and Fourier transform infrared (FT-IR) spectrometer. PVA not only stabilized the colloid but also played a role in preventing further growth of SPION followed by the formation of large agglomerates by chemisorption on the surface of particles. A rich behavior in particle size, particle formation, and super paramagnetic properties is observed as a function of molarity and stirring conditions. The particle size and the magnetic properties as well as particle shape and aggregation (individual nanoparticles, magnetic beads, and magnetite colloidal nanocrystal clusters (CNCs) are found to be influenced by changes in the stirring rate and the base molarity. The formation of magnetic beads results in a decrease in the saturation magnetization, while CNCs lead to an increase in saturation magnetization. On the basis of the DOE methodology and the resulting 3-D response surfaces for particle size and magnetic properties, it is shown that optimum regions for stirring rate and molarity can be obtained to achieve coated SPION with desirable size, purity, magnetization, and shape.     

Separation Axioms on ℕ∞-Systems

Projection algebras (spaces) are nothing but -systems. Computer scientists use these algebras for the specification of infinite objects (process) which can not be denoted by finite terms. Using the closure operator given in [9], we consider these algebras as topological spaces and investigate the separation axioms for them. Among other things, we get some equivalent conditions to separatedness defined and studied in [9]. We also study the relations between separatedness and other separation axioms. Finally, we characterize the subdirectly irreducible projection algebras.     

Magnetically separable and recyclable g-C<Subscript>3</Subscript>N<Subscript>4</Subscript> nanocomposite catalyzed one-pot synthesis of substituted imidazoles

A green, reliable synthetic method and highly efficient one-pot three-component synthesis of 2,4,5-trisubstituted imidazoles from 1,2-diketones, aldehydes and ammonium acetate in the presence of recyclable magnetic graphitic carbon nitride nanocomposite (Fe₃O₄@g-C₃N₄) has been developed. Various imidazole derivatives were obtained in moderate to excellent yields and high purity after recrystallization from ethanol. Interestingly, the low-cost Fe₃O₄@g-C₃N₄ a nontoxic and inexpensive catalyst showed excellent recyclability using an external magnet without loss of parent catalytic activity even after ten cycles and its provides new opportunities for the truly environmental friendliness methodology.     

Magnetic g-C3N4 nanocomposite-catalyzed environmentally benign aminolysis of epoxide

Research on Chemical Intermediates - A magnetic graphitic carbon nitride (g-C3N4) nanocomposite was prepared and used as a novel magnetically retrievable nanocatalyst for efficient ring opening of...     

Identification of catecholamine neurotransmitters using fluorescence sensor array

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual catecholamine (i.e., dopamine, norepinephrine, and l-DOPA) and their mixtures in the concentration range of 0.25–30 μmol L⁻¹. Finally, we found that the sensor had capability to identify the various catecholamines in urine sample.     

Extrapolated positive definite and positive semi-definite splitting methods for solving non-Hermitian positive definite linear systems

Applications of Mathematics - Recently, Na Huang and Changfeng Ma in (2016) proposed two kinds of typical practical choices of the PPS method. In this paper, we extrapolate two versions of the PPS...     

An alternative proof of a characterization of Cohen-Macaulay bipartite graphs

Recently, Herzog and Hibi explicitly described all Cohen-Macaulay bipartite graphs by using the Stanley-Reisner ideal of the Alexander dual of the simplicial complex Δ _P associated to a finite poset P. In this paper, we will present a short proof that does not use the Stanley-Reisner ideal of the Alexander dual of Δ _P .