Triple-flame propagation in a parallel flow: an analytical study

We present an analytical study of triple-flame propagation in a two-dimensional mixing layer against a parallel flow. The problem is formulated within a constant density thermo-diffusive model, and solved analytically in the asymptotic limit of large activation energy of the chemical reaction for flames thin compared with their typical radius of curvature. Explicit expressions are obtained in this limit, describing the influence of the flow on the triple-flame. The results are expected to be applicable when the ratio between the flow-scale and the flame-front radius of curvature (which is mainly dictated by concentration gradients) is of order unity, or larger. When this ratio is large, as in the illustrative case of a Poiseuille flow in a porous channel considered here, the flow is found to negligibly affect the flame structure except for a change in its speed by an amount which depends on the stoichiometric conditions of the mixture. On the other hand, when this ratio is of order unity, the flow is able to significantly wrinkle the flame-front, modify its propagation speed, and shift its leading edge away from the stoichiometric line. The latter situation is investigated in the illustrative case of spatially harmonic flows. The results presented describe, in particular, how the leading-edge of the flame-front can be determined in terms of the flow amplitude A which is critical in determining the flame speed. The latter is found to depend linearly on A in the first approximation with a correction proportional to the flame thickness multiplied by , for |A| sufficiently large. The effect of varying the flow-scale on flame propagation in this context is also described, with explicit formulae provided, and interesting behaviours, such as non-monotonic dependence on the scale, identified.     

Thermoelectric power factor of RuSr2GdCu2O8

The influence of thermal treatment between 1273 and 1333?K in an oxygen atmosphere on the perovskite system RuSr₂GdCu₂O₈ was studied by X-ray diffraction (XRD), scanning electron microscopy, electrical resistivity and Seebeck coefficient measurements. The XRD patterns revealed that the phase purity depends on the sintering process. The samples were found to exhibit very small crystallite sizes in the nanometer range. The electrical resistivity was found to be strongly correlated with the heat treatment. The temperature dependence of electrical resistivity for one sample revealed semiconducting behavior, whereas the others exhibit metallic behavior. All the investigated samples exhibit a positive thermoelectric power, indicating the predominance of positive charge carriers. It was found that the power factor reaches a maximum value of 0.4?×?10^?4?W?m^?1?K^?2 at 300?K.     

Rundtischgespräche

Separation of cesium and cobalt from simulated medium active waste (MAW) by coprecipitation with hexacyanocobaltate (III) salts has been discussed. It has been found that coprecipitation of cesium or cobalt from MAW can be carried out successfully by using only potassium hexacyanocobaltate (III). The retention of cesium and cobalt has been studied over a wide range of pH, from zero to 12. A comparison of cobalti-, ferro- and ferricyanide complexes towards the retention of cesium at different pH values has also been made. The retention capacity of cobalticyanide precipitates for cesium and cobalt at pH 1.6 has been reported.     

Part 1: An Appraisal of New Radioisotope Techniques in the Study of Iodine Metabolism

The use of different radioiodines and technetium for the evaluation of the thyroid functions has been discussed. Preparation oe labelled iodotyrosines and labelled throxine is mentioned for the convey of different radiochemical tests and for the use of reference standards, necessary for the identification of separated amino acids. Paper chromatography and paper electrophoresis techniques are used for the identification and determination of iodinated amino acids or homones, either in the free state or bound to the proteins. Tc^99m is employed to substitute radioiodine in the study of uptake measurements of the thyroid gland and to evaluate the excretion of the isotope in urine. Thiourea-S³⁵ is employed, for the first time to human, to study the metabolism of the substance in different thyroid disorders.     

Frobenius manifolds from regular classical W-algebras

We obtain polynomial Frobenius manifolds from classical W-algebras associated to regular nilpotent elements in simple Lie algebras using the related opposite Cartan subalgebras.     

Aminated dendritic surfaces characterization: a rapid and versatile colorimetric assay for estimating the amine density and coating stability

The functionalization of surfaces with amino groups is used in many application areas such as in industrial biocatalytic processes for the development of medical biomaterials and in the environment for removing pollutants from water. Amino group density and grafting stability are often related to functionalized material performances; thus, their characterizations are of prime importance. The determination of amino density and grafting stability on polymeric material (e.g. polypropylene, polystyrene and cylco olefin copolymer) is often time consuming and sometimes presents technical constraints, more particularly with non-flat materials. In this paper, we report a novel colorimetric assay using the Coomassie Brilliant Blue dye for both amino density determination and grafting stability measurement. The assay named ADECA for “Amino Density Estimation by Colorimetric Assay” is sensitive, rapid, robust and versatile. We demonstrate that ADECA makes the evaluation of aminated materials performances possible for numerous material compositions, formats and chemistries used for grafting. Our study focuses on dendrigraft of poly-l-lysine and poly(amidoamine) dendrimers dendritic materials.     

Simultaneous determination of ibuprofen and paracetamol using derivatives of the ratio spectra method

Simple, rapid and accurate new method is described for the simultaneous determination of ibuprofen (IB) and paracetamol (PA) in two components mixture and Cetofen tablets. The method depends on the derivative of the ratio spectra DD by measurement of the amplitude of ¹DD at 225.6 nm and the amplitude of ²DD at 238.9 nm for IB and PA. Calibration graphs are linear in the range 2–32 (LOD 0.53) and 2–24 (LOD 0.57) μg/ml IB and PA, respectively. The proposed method is successfully applied for simultaneous determining IB and PA in authentic mixtures and Cetofen tablets.     

Interaction of carbene and olefin donors with [Cl2PN]3: exploration of a reductive pathway toward (PN)3

The iminophosphine-phosphazene [P(III)-P(V)] heterocyclic adduct [IPr·PN(PCl(2)N)(2)] was prepared via reduction of the cyclic phosphazene [Cl(2)PN](3) in the presence of the carbene donor IPr {IPr = [(HCNDipp)(2)C:], where Dipp = 2,6-(i)Pr(2)C(6)H(3)}. By contrast, the treatment of [Cl(2)PN](3) with the N-heterocyclic olefin IPr═CH(2) yielded the olefin-grafted phosphazene ring [(IPr═CH)P(Cl)N(PCl(2)N)(2)].     

A facile, modular and high yield method to assemble three-dimensional DNA structures

We describe a rapid and quantitative method to generate DNA cages of deliberately designed geometry from readily available starting strands. Balancing the incorporation of sequence uniqueness and symmetry in a face-centered approach to 3D construction can result in triangular (TP), rectangular (RP), and pentagonal prisms (PP) without compromising the potential for nanostructure addressability.     

An equilibrium ab initio atomistic thermodynamics study of chlorine adsorption on the Cu(001) surface

The effect of chlorine (Cl) chemisorption on the energetics and atomic structure of the Cu(001) surface over a wide range of chlorine pressures and temperatures has been studied using equilibrium ab initio atomistic thermodynamics to elucidate the formation of cuprous chloride (CuCl) as part of the Deacon reaction on copper metal. The calculated surface free energies show that the 1/2 monolayer (ML) c(2 × 2)-Cl phase with chlorine atoms adsorbed at the hollow sites is the most stable structure for a wide range of Cl chemical potential, in agreement with experimental observations. It is also found that at very low pressure and exposure, but elevated temperature, the 1/9 ML and 1/4 ML phases become the most stable. By contrast, a high coverage of Cl does not lead to thermodynamically stable geometries. The subsurface adsorption of Cl atoms, however, dramatically increases the stability of the 1 ML and 2 ML adsorption configurations providing a possible pathway for the formation of the bulk-chloride surface phases in the kinetic regime.