Development of Abraham model correlations for describing the transfer of molecular solutes into propanenitrile and butanenitrile from water and from the gas phase

Experimental solubilities were measured for 20 crystalline organic solutes dissolved in propanenitrile and for 13 crystalline organic solutes dissolved in butanenitrile at 298.15 K. Infinite dilution activity coefficient data for solutes dissolved in propanenitrile and butanenitrile have been compiled from the published chemical and engineering literature and converted into gas-to-liquid partition coefficients and water-to-organic solvent partition coefficients through standard thermodynamic relationships. Abraham model correlations were developed for describing solute transfer into both propanenitrile and butanenitrile by combining our measured solubility data with the partition coefficients that we calculated from the published activity coefficient data. The derived Abraham model correlations were found to back-calculate the observed partition coefficients and molar solubility data to within 0.14 log units.     

Synthesis, crystal structure, and spectroscopic characterization of af-dichloro-bd,ec-bis{μ[2-(1-methyl-2-piperidinyl)ethanethiolato]-S,N,μ-S} dipalladium(II)

The reaction of 2-(1-methyl-2-piperidinyl)ethanethiol with sodium tetrachloro-palladate(II) at pH = 8 yields a yellow precipitate of formula [Pd₂(C₈H₁₆NS)₂Cl₂] which crystallized in the orthorhombic space group Pcab with a = 22.050(4) Å, b = 14.644(3) Å, c = 13.834(3) Å, V = 4467(3) ų, and Z = 8. The organic ligands chelate to one Pd atom through the S and N atoms and bridges to another Pd atom through the S atom to form a dimer in which each molecule of the organic ligand has the same chirality. IR, UV—Vis and ¹H NMR spectra are presented for this compound.     

Cobalt(III) complexes with aminothiolates

Summary This article describes some complexes of cobalt(III) with -mercaptopropylamine,N, N-dimethyl--mercaptopropylamme andN,N-dimethyl--mercaptoethylamine. The compounds are of stoichiometry [Co(ligand)₃], [Co₃(ligand)₆]_X (X=Cl or Br) and [Co(ligand)₃]X₃ (X=Cl or ClO₄). -Mercaptopropylamine yields both chelated and non-chelated compounds while theN,N-dimethyl derivatives yield only non-chelated complexes. This behaviour contrasts with the results obtained with nickel(II).     

Self-assembly of mercaptane-metallacarborane complexes by an unconventional cooperative effect: a C-H...S-H...H-B hydrogen/dihydrogen bond interaction

The existence of a dihydrogen bond (S-H...H-B) and its combination with a C-H...S hydrogen bond in an unusual cooperative effect are demonstrated from a combination of experimental and theoretical methods. This cooperative effect seems to be responsible for self-assembly of mercaptane-metallacarborane complexes such as closo-[3-Ru(eta6-C6H6)-8-HS-1,2-C2B9H10] (1) and closo-[3-Co(eta5-C5H5)-8-HS-1,2-C2B9H10] (3), which present identical supramolecular two-dimensional polymeric networks. The findings, besides documenting structurally the first S-H...(H-B)2 dihydrogen bond and the unconventional cooperative ability of a boron-attached SH group, prove that substituted carboranes have the potential to serve as building blocks for assembling complex structures.     

Membrane thickness and preparation temperature as key parameters for controlling the macrovoid structure of chiral activated membranes (CAM)

A macrovoid structure is formed in polysulfone (PSf) polymeric membranes prepared by the immersion technique using N-dimethylformamide (DMF)/water as a solvent/non-solvent pair. It is actually important controlling the macrovoid formation process, because macrovoids can cause unwanted mechanical failure during high-pressure applications. In order to control the formation of these structures, the influence of different parameters like membrane thickness, solvent additives (isopropyl myristate, IPM or N-hexadecyl-l-hydroxypriline, HHP), temperature of the coagulation bath, and solvent/non-solvent pair has been studied for chiral activated membranes. With the same purpose, corresponding membranes where physically characterized by scanning electron microscopy (SEM) measurements of their cross-section images. Those SEM images have been treated by the software IFME^®, which provides the parameters of asymmetry and irregularity of the membranes. The surface of the membranes has been analyzed by atomic force microscopy (AFM) and brightness analysis in order to calculate their roughness. A comparison of the same PSf membranes, but prepared by evaporation precipitation, or by using chloroform/methanol as solvent/non-solvent pair during the immersion precipitation step, has been also checked. That paper helps us to understand and predict which will be the best conditions to prepare the optimum membranes.     

Limiting search cost distribution for the move-to-front rule with random request probabilities

Consider a list of n files whose popularities are random. The list is updated according to the move-to-front rule. When the induced Markov chain is at equilibrium, we explicitly compute the limiting distribution of the search-cost per item as n tends to infinity. The uniform distribution results in the largest search cost.     

Linearization of a class of non-linear systems modelled by multibond graphs

Based on non-linear systems described by multibond graphs, a procedure designed to present symbolic linearization of these multibond graphs, is presented in this paper. Firstly, a junction structure of a multibond graph with multiport gyrators that represent Eulerian junction structures is proposed. In addition, non-linear multiport resistors are considered. By knowing the non-linear causal paths and loops of the non-linear multibond graph, the linearization is obtained by two steps: (1) The original multibond graph on the nominal operating point is evaluated; (2) New and additional paths based on the non-linear causal paths and loops are included. The state space representation of the linearized multibond graph using the corresponding junction structure is presented. An advantage of this methodology is its ability to allow the user to define a nominal operating point in which the linearization will be carried out.

In order to apply the proposed methodology, two physical systems are modelled and linearized by multibond graphs: a synchronous generator and a two degrees of freedom PUMA. Simulation results of these non-linear and linearized systems are shown.     

Cocyclic two-circulant core Hadamard matrices

Journal of Algebraic Combinatorics - The two-circulant core (TCC) construction for Hadamard matrices uses two sequences with almost perfect autocorrelation to construct a Hadamard matrix. A...     

Pappus’ theorem and a construction of complex Kleinian groups with rich dynamics

Pappus’ theorem is used to produce and study discrete subgroups of PSL(3, ?) with very rich dynamics. We get an example of a subgroup of PSL(3, ?) which is not conjugate to any subgroup of PU(2, 1) nor to any subgroup of Aff(?²), its Kulkarni region of discontinuity is non-empty and its complement, the Kulkarni limit set, contains infinitely many complex projective lines in general position. This construction is based on a representation of the group SL(2, ?) in the projective group PSL(3, ?).