Numerical differentiation on scattered data through multivariate polynomial interpolation

BIT Numerical Mathematics - We discuss a pointwise numerical differentiation formula on multivariate scattered data, based on the coefficients of local polynomial interpolation at Discrete Leja...     

A note on the two-stage hybrid flow shop problem with dedicated machines

In this paper we introduce a new dominance rule for the two-stage hybrid flow shop problem with dedicated machines. The rule is then used to construct a dominating set. The efficiency of the proposed rule is shown through an analysis of the dominating set cardinality.     

The Webster scalar curvature problem on the three dimensional CR manifolds

In this paper, we prove some existence results for the Webster scalar curvature problem on the three dimensional CR compact manifolds locally conformally CR equivalent to the unit sphere S³ of C². Our methods are based on the techniques related to the theory of critical points at infinity.     

Electrocatalytic Determination of Sulfite at Immobilized Microdroplet Liquid|Liquid Interfaces: The EIC′ Mechanism

Liquid|liquid interfaces provide a natural boundary and a reactive interface where an organic phase is in contact with an aqueous analyte. The selectivity of ion transfer processes at liquid|liquid interfaces can help to provide sensitivity, introduce reactive reagents, or allow analyte accumulation at the electrode surface. In this study, microdroplet deposits of the organic liquid 4‐(3‐phenylpropyl)‐pyridine (PPP) with the ferrocenylmethyl‐dodecyldimethylammonium⁺ (FDA⁺) redox system are deposited onto a basal plane pyrolytic graphite electrode and employed to transfer anions from the aqueous into the organic phase. A clear trend of more hydrophobic anions transferring more readily (at more negative potentials) is observed and an ESI‐mass spectrometry method is developed to confirm the transfer. Subsequently, the electrocatalytic oxidation of sulfite, SO₃^2?, within the organic phase and in the presence of different electrolyte anions is investigated. Competition between sulfite transfer and inert anion transfer occurs. The electrocatalytic sulfite oxidation is suppressed in the presence of PF₆^? and occurs most readily in the presence of the hydrophilic nitrate anion. The resulting process can be classified as an electrocatalytic EIC′‐process (E: electron transfer; I: ion transfer; C: chemical reaction step). The effectiveness of the electrocatalytic process is limited by i) competition during anion transfer and ii) the liquid|liquid interface acting as a diffusion barrier. The analytical sensitivity of the method is limited to ca. 100 μM SO₃^2? (or ca. 8 ppm) and potential approaches for improvement of this limit are discussed.     

Synthesis and structure of the unsymmetrical β-diimine precursor: The β-iminoamine

The reaction of benzoylacetone with ortho-substituted aniline derivatives gives the unsymmetrical β-iminoamine ligands (5–8) with high yields. A convenient synthesis is described. These compounds have been characterized by NMR and IR spectroscopies. The structure of the β-iminoamine 5, 3-N-(2,6-diisopropylphenylamino)-1-phenyl-1N-(2,6-diisopropylphenylimino)but-2-ene, was solved by X-ray diffraction methods.     

EGB-promoted electrochemical synthesis of 6-thioxo-[1,3,5]-triazinane-2,4 dione derivatives

A simple method for the synthesis of 6-thioxo-[1,3,5]-triazinane-2,4-dione derivatives was reported. The electrogenerated cyanomethyl base obtained from electroreduction of neat acetonitrile assisted the reaction between thiourea derivatives and alkyl or aryl isocyanate. This protocol had the advantage of giving good yields using mild conditions. The obtained products have been identified by spectroscopic data, mass spectrometry, and high-resolution mass spectra or elemental analysis.     

Synthesis, crystal structure and mono-dimensional thallium ion conduction of TlFe0.22Al0.78As2O7

A new solid solution TlFe_0.22Al_0.78As₂O₇ has been synthesized by a solid-state reaction. The structure of the title compound has been determined from a single-crystal X-ray diffraction and refined to final values of the reliability factors: R(F²)=0.030 and wR(F²)=0.081 for 1343 independent reflections with I>2σ(I). It crystallizes in the triclinic space group P-1, with a=6.296(2) Å, b=6.397(2) Å, c=8.242(2) Å, α=96.74(2)°, β=103.78(2)°, γ=102.99(3)°, V=309.0(2) Å³ and Z=2. The structure can be described as a three-dimensional framework containing (Fe/Al)O₆ octahedra connected through As₂O₇ groups. The metallic units and diarsenate groups share oxygen corners to form a three-dimensional framework with interconnected tunnels parallel to the a, b and c directions, where Tl⁺ cations are located. The ionic conductivity measurements are performed on pellets of the polycrystalline powder. At 683 K, The conductivity value is 5.23×10⁻⁶ S cm⁻¹ and the ionic jump activation energy is 0.656 eV. The bond valence analysis reveals that the ionic conductivity is ensured by Tl⁺ along the [001] direction.     

The Webster scalar curvature revisited: the case of the three dimensional CR sphere

In this paper we consider the problem of prescribing the Webster scalar curvature on the three CR sphere of ${\mathbb{C}^{2}}$ . We use techniques related to the theory of critical points at infinity, and obtain existence results for curvature satisfying an assumption of Bahri?CCoron type.     

Étude de l’activité catalytique des argiles pontées aluminium,zirconium et cérium dans la synthèse du 2,2-diméthyl-1,3-dioxolane

The purified Tunisian clay G and the commercialized American clay W were pillared with zirconium, aluminum and mixed pillars zirconium–aluminum, cerium–zirconium, cerium–aluminum, and cerium–zirconium–aluminum. These different clays were used in the synthesis of 2,2-dimethyl-1,3-dioxolane 3 by acetalyzation of acetone 2 with ethylene glycol 1 under autogenously pressure and without solvent. Results indicate that the yield of product 3 depends of the nature and the acidity of the clay used and the time of reaction.