A Simple and Efficient Synthesis of 2-Substituted 3-Diethylphosphono 5-Methylfurans

An efficient carbanionic synthesis of the phosphonic dicarbonylated compounds 2 was achieved and used as key intermediates in the synthesis of the phosphonic furans 4 by acid-induced Paal-Knorr cyclization reaction.     

Microcrystalline testing used in combination with Raman micro‐spectroscopy for absolute identification of novel psychoactive substances

Two new psychoactive substances, namely 4‐methylmethcathinone (mephedrone) and 5,6‐methylenedioxy‐2‐aminoindane (MDAI) were analysed with a novel combination of microcrystalline tests followed by Raman micro‐spectroscopy to facilitate their absolute identification. The discrimination power of the proposed combination was successfully demonstrated through the analysis of the positional isomers 2‐ and 3‐methylmethcathinone. The addition of mercury dichloride as a microcrystalline test reagent produced specific microcrystals of each tested analyte. The robustness of the method was evaluated in the presence of common cutting agents (caffeine and benzocaine) as well as on street samples. The crystal lattice structures of mephedrone, 2‐methylmethcathinone and MDAI mercury dichloride microcrystals were determined by single crystal X‐ray diffraction. This confirmed the presence of both drug and reagent together in the lattice and accounts for the distinct habit of the observed microcrystals. Raman spectra of the formed microcrystals differed from those obtained from their standard salt form by loss and/or gain of some vibrational modes. Particularly important was the appearance of the mercury chloride link to each tested drug molecule which showed as strong bands at low wavenumbers. Its presence was corroborated by its detection in the crystal lattice. It was therefore concluded that microcrystalline testing followed by Raman micro‐spectroscopy satisfies the technique combination requirement for psychoactive substances recommended by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) and provides a rapid and cheap analysis route. The proposed technique combination also aids the development of new microcrystalline tests as it allows for confirmation of the uniqueness of the developed microcrystals almost in‐situ rather than growing single crystals for often long periods of time needed for single crystal X‐ray diffraction analysis. Copyright © 2016 John Wiley & Sons, Ltd.     

Use of noncontact dilatometry for the assessment of the sintering kinetics during mullitization of three kaolinitic clays from Cameroon

Noncontact dilatometry, compared to differential scanning calorimetry (DSC), was used together with scanning electron microscopy and densification behavior studies to investigate the parameters that govern the kinetics of transformation of kaolin to mullite during sintering. Three kaolinitc clays from Cameroon, with different SiO₂/Al₂O₃ molar ratio, were examined. The temperatures of mullite nucleation were 973, 979, and 984 °C at 5 °C/min heating rate, respectively, for values of SiO₂/Al₂O₃ molar ratio equal to 4.22, 2.22, and 2.08. At 20 °C/min heating rate, the temperatures are shifted to higher values, 992, 997, and 1,001 °C. The mullitization phenomenon, which includes a first step of nucleation and a second one of crystal growth, presented activation energy in the range of 650–730 kJ/mol, depending on the nature of the sample investigated. These values, obtained by noncontact dilatometer measurements, were comparable to those obtained by means of DSC and are in agreement with literature values. The difference in sintering kinetics for the three kaolinitic clays could explain the different morphologies obtained for the mullite grains.     

Local structure and thermodynamics of a core-softened potential fluid: theory and simulation.

Phase behavior and structural properties of homogeneous and inhomogeneous core-softened (CS) fluid consisting of particles interacting via the potential, which combines the hard-core repulsion and double attractive well interaction, are investigated. The vapour-liquid coexistence curves and critical points for various interaction ranges of the potential are determined by discrete molecular dynamics simulations to provide guidance for the choice of the bulk density and potential parameters for the study of homogeneous and inhomogeneous structures. Spatial correlations in the homogeneous CS system are studied by the Ornstein-Zernike integral equation in combination with the modified hypernetted chain (MHNC) approximation. The local structure of CS fluid subjected to diverse external fields maintaining the equilibrium with the bulk CS fluid are studied on the basis of a recently proposed third order+second order perturbation density functional approximation (DFA). The accuracy of DFA predictions is tested against the results of a grand canonical ensemble Monte Carlo simulation. Reasonable agreement between the results of both methods proves that the DFA theory applied in this work is a convenient theoretical tool for the investigation of the CS fluid, which is practically applicable for modeling numerous real systems.     

The influence of molecular shape and charge distribution on the molecular approach in solution. NMR dipolar relaxation studies of the many-body effects

The paramagnetic dipolar spin-lattice relaxation of nuclear spins is expressed in terms of the geometrical and dynamical parameters of the molecules and used to analyze the intra- and intermolecular microdynamics. The possible conformational changes of a TEMPOL nitroxide-labelled sugar in deuterated chloroform are studied and then the intermolecular processes are considered. The influence of the discrete polar natures of acetonitrile, chloroform, and methanol on the TEMPOL solvation dynamics is recognized. The importance of the water structure on the collisional approach of two attractive ions is emphasized. Finally, the attractive effects of the dipole-dipole electrostatic forces are shown for the water/TEMPOL pair. Diffusion and jump analytical theories, integral equations of statistical mechanics, and Monte-Carlo simulations of the diffusion are combined to treat the anisotropic interactions and the many-body effects.     

A reduced-order model manifold technique for automated structural defects judging using the PGD with analytical validation

Automation is conquering new fields on a daily basis. Aiming for faster and more reliable products, industrials as well as researchers are oriented into automation. Non-destructive testing as well as defect quantification is not an exception. In fact, decisions with minimum allowable error are sought in real-time when facing any potential defect. In this work, we suggest a comprehensive method based on model order reduction techniques to judge if a structure shall be salvaged. The real-time decision is based on multidimensional parametric simulation, performed offline, using the Proper Generalized Decomposition (PGD). The PGD is a model order reduction technique that allows circumventing the curse of dimensionality by using domain decomposition. Therefore, the 6D simulation illustrated in this paper is performed within a few minutes on a standard laptop. Later on, a stress concentration manifold is built and used online for decision-making. The manifold is validated on a few selected solutions solved analytically using an analytical procedure. The aforementioned procedure is developed, in this paper, to calculate the tangential stress around circular holes of different sizes, in an infinite isotropic plate containing any number of holes and subjected to in-plane pressure loading at the tip of the infinite plate. The procedure is based on determining two Muskhelishvili complex potentials in terms of complex Fourier series, and applying the Schwartz alternating method repeatedly until the boundary conditions on the contour of every hole are satisfied.     

Solution of fuzzy equations with extended operations

Assuming that 1 is any operation defined on a product set X × Y and taking values on a set Z, it can be extended to fuzzy sets by means of Zadeh's extension principle. Given a fuzzy subset C of Z, it is here shown how to solve the equation $\text{A 1 B = C}$ (or $\text{A 1 B ? C}$) when a fuzzy subset A of X (or a fuzzy subset B of Y) is given. The methodology we provide includes, as a special case, the resolution of fuzzy arithmetical operations, i.e. when 1 stands for +, ?, × or ÷, extended to fuzzy numbers (fuzzy subsets of the real line). The paper is illustrated with several examples in fuzzy arithmetic.     

Fluctuation spectrum of fluid membranes coupled to an elastic meshwork: jump of the effective surface tension at the mesh size

We identify a class of composite membranes: fluid bilayers coupled to an elastic meshwork that are such that the meshwork's energy is a function F(el)[A(xi)] not of the real microscopic membrane area A, but of a smoothed membrane's area A(xi), which corresponds to the area of the membrane coarse grained at the mesh size xi. We show that the meshwork modifies the membrane tension sigma both below and above the scale xi, inducing a steep crossover of amplitude deltasigma=dF(el)/dA(xi). The predictions of our model account for the fluctuation spectrum of red blood cell membranes coupled to their cytoskeleton. Our results indicate that the cytoskeleton might be under extensional stress, which would provide a means to regulate available membrane areas. We also predict an observable tension jump for membranes decorated with polymer "brushes."