Development of an impedimetric sensor based on carbon dots and chitosan nanocomposite modified electrode for Cu(II) detection in water

Journal of Solid State Electrochemistry - The fast and sensitive detection of copper ions would be essential for water monitoring. Herein, we report a novel development of an impedimetric sensor...     

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.     

The rearrangement of some cyclopentanone-aryloximes: synthesis of (±)-aplysin, (±)-filiformin and of their debromo analogues.

Upon acid catalyzed rearrangement after Sheradsky, the aryloximes A gave the tricyclic aminals C, which suffered hydrolysis to lactols E. The unique alcohol 29 was then prepared through a highly stereoselective equilibration-reductive alkylation of the epimeric mixture of lactols 22a,b. Two routes, one of which was stereospecific, allowed cyclization of 29 to (±)-aplysin 34. The yield was 2.5 % from oximes 2a,b. The isomeric epi-aplysin 35 and filiformin 36 were also obtained from 29. The debromo analogues 37,38 and 39 and their trideutero derivatives 41,42 and 43 were synthesized along similar line and allowed unequivocal structure elucidation by NMR spectroscopy.     

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.     

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.     

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...     

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.     

Electronic structure of cubic ErxGa1−xN using the LSDA+U approach

Electronic structure calculations were performed for substitutional erbium rare-earth impurity in cubic GaN using density-functional theory calculations within the LSDA+U approach (local spin-density approximation with Hubbard-U corrections). The LSDA+U method is applied to the rare-earth 4f states. The Er_xGa_1−xN is found to be a semiconductor, where the filled f-states are located in the valence bands and the empty ones above the conduction band edge. The filled and empty f-states are also shown to shift downwards and upwards in the valence and conduction bands, respectively, with increase in the U potentials.     

Hydroxylation of Aromatics by H2O2 Catalyzed by Mononuclear Non-heme Iron Complexes: Role of Triazole Hemilability in Substrate-Induced Bifurcation of the H2O2 Activation Mechanism

Rieske dioxygenases are metalloenzymes capable of achieving cis-dihydroxylation of aromatics under mild conditions using O₂ and a source of electrons. The intermediate responsible for this reactivity is proposed to be a cis-Fe^V(O)(OH) moiety. Molecular models allow the generation of a Fe^III(OOH) species with H₂O₂, to yield a Fe^V(O)(OH) species with tetradentate ligands, or {Fe^IV(O); OH^.} pairs with pentadentate ones. We have designed a new pentadentate ligand, mtL₄², bearing a labile triazole, to generate an “in-between” situation. Two iron complexes, [(mtL₄²)FeCl](PF₆) and [(mtL₄²)Fe(OTf)₂]), were obtained and their reactivity towards aromatic substrates was studied in the presence of H₂O₂. Spectroscopic and kinetic studies reflect that triazole is bound at the Fe^II state, but decoordinates in the Fe^III(OOH). The resulting [(mtL₄²)Fe^III(OOH)(MeCN)]²⁺ then lies on a bifurcated decay pathway (end-on homolytic vs. side-on heterolytic) depending on the addition of aromatic substrate: in the absence of substrate, it is proposed to follow a side-on pathway leading to a putative (N₄)Fe^V(O)(OH), while in the presence of aromatics it switches to an end-on homolytic pathway yielding a {(N₅)Fe^IV(O); OH^.} reactive species, through recoordination of triazole. This switch significantly impacts the reaction regioselectivity.     

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.