Thermal decomposition kinetics of tetraalkylammonium and dimethylpyridinium salts of the complex anion bis(1,3-dithiole-2-thione-4,5-dithiolate) bismuthate (−1)

In the present work, thermal decomposition kinetics of tetraalkylammonium and 1,4-dimethylpyridinium salts of the complex anion bis(1,3-dithiole-2-thione-4,5-dithiolate) bismuthate ([Bi(dmit)₂]⁻) are addressed. Kinetic parameters for the decomposition reactions were obtained utilizing the Ozawa and Coats–Redfern (CR) models. Entropy, enthalpy, and free energy of decomposition processes were calculated from the CR results, providing information on the thermodynamic characteristics of the processes. The most probable mechanisms of thermal decomposition were indicated for the studied systems, along with their kinetic and thermodynamic parameters.     

Cell decomposition of almost smooth real algebraic surfaces

Let Z be a two dimensional irreducible complex component of the solution set of a system of polynomial equations with real coefficients in N complex variables. This work presents a new numerical algorithm, based on homotopy continuation methods, that begins with a numerical witness set for Z and produces a decomposition into 2-cells of any almost smooth real algebraic surface contained in Z. Each 2-cell (a face) has a generic interior point and a boundary consisting of 1-cells (edges). Similarly, the 1-cells have a generic interior point and a vertex at each end. Each 1-cell and each 2-cell has an associated homotopy for moving the generic interior point to any other point in the interior of the cell, defining an invertible map from the parameter space of the homotopy to the cell. This work draws on previous results for the curve case. Once the cell decomposition is in hand, one can sample the 2-cells and 1-cells to any resolution, limited only by the computational resources available.     

Solid-phase synthesis of linear and cyclic peptides containing a calix[4]arene amino acid

Solid-phase synthesis is used to obtain new linear and cyclic N,C-linked peptidocalixarenes. The synthetic strategy allows, for the first time, the condensation of a calix[4]arene amino acid during the stepwise elongation sequence of the peptide. An important role is played by the lower rim functionalization of the calixarene since it modulates the flexibility of the calixarene scaffold and the conformational properties of the resulting non-natural peptide.     

Magnetic and transport studies of σ-phase Fe50V50 alloys with different thermal history

The influence of the formation conditions of the sigma phase in an equiatomic FeV alloy on the magnetic and electric transport properties is studied. It is found that a sigma phase sample with higher resistivity (subject to a previous long annealing) has a much sharper magnetic transition than one formed after a shorter heat treatment and quenching, although both have very similar magnetic moments and ferromagnetic transition temperatures (T_c ～ 15 K from minimum dM/dT).     

Fractional volume integration in two-dimensional NMR spectra: CAKE, a Monte Carlo approach

Quantitative information from multi-dimensional NMR experiments can be obtained by peak volume integration. The standard procedure (selection of a region around the chosen peak and addition of all values) is often biased by poor peak definition because of peak overlap. Here we describe a simple method, called CAKE, for volume integration of (partially) overlapping peaks. Assuming the axial symmetry of two-dimensional NMR peaks, as it occurs in NOESY and TOCSY when Lorentz-Gauss transformation of the signals is carried out, CAKE estimates the peak volume by multiplying a volume fraction by a factor R. It represents a proportionality ratio between the total and the fractional volume, which is identified as a slice in an exposed region of the overlapping peaks. The volume fraction is obtained via Monte Carlo Hit-or-Miss technique, which proved to be the most efficient because of the small region and the limited number of points within the selected area. Tests on simulated and experimental peaks, with different degrees of overlap and signal-to-noise ratios, show that CAKE results in improved volume estimates. A main advantage of CAKE is that the volume fraction can be flexibly chosen so as to minimize the effect of overlap, frequently observed in two-dimensional spectra.     

Community repeated interaction and strategic delegation

A large population of fixed-type agents engage in exclusive pairwise relationships in a decentralized setting. At the onset, agents randomly meet in pairs under private information of individual time-invariant types. They play a voluntary contribution game. At the end of the first period, members of each pair either stay together in the second period, in which case reported information is common knowledge, or quit and meet randomly new partners, under private information of individual types. Thus, either long-term or short-term relationships may arise. We show that there are values of the parameters such that information extracted in the first period has a positive effect on social efficiency. We give an interpretation of our results in terms of advantageous delegation of decisions to uninformed agents. Finally, we consider several extensions of the model in which our results still hold.     

Inherently Chiral Spider‐Like Oligothiophenes

The racemate of an inherently chiral “spider‐like” octathiophene monomer T8₃ , in which chirality is generated by torsion in its backbone, was synthesized. The racemate was resolved into configurationally stable antipodes by HPLC on a chiral stationary phase. Electrooxidation of the enantiomers resulted in materials displaying high enantiorecognition ability towards the antipodes of some chiral probes. Moreover, the T8₃ racemate demonstrated great aptitude to stimulate formation of 3D rigid architectures if used as a cross‐linking monomer for molecular imprinting. This feature was exploited to devise a molecularly imprinted polymer‐based chemosensor selective for a thymine–adenine oligonucleotide.