An Infinite Antichain of Planar Tanglegrams

Contrary to the expectation arising from the tanglegram Kuratowski theorem of Czabarka et al. (SIAM J. Discrete Math. 31(3), 1732–1750, 2017), we construct an infinite antichain of planar tanglegrams with respect to the induced subtanglegram partial order. R.E. Tarjan, R. Laver, D.A. Spielman and M. Bóna, and possibly others, showed that the partially ordered set of finite permutations ordered by deletion of entries contains an infinite antichain, i.e., there exists an infinite collection of permutations, such that none of them contains another as a pattern. Our construction adds a twist to the construction of Spielman and Bóna (Electr. J. Comb. 7, N2, 2000).

     

Kinetics Study of the Thermal Decomposition of Post-consumer Poly(Ethylene Terephthalate) in an Argon Atmosphere

The thermal decomposition of post-consumer samples of a carbonated water bottle made of poly(ethylene terephthalate), PC-PET, was examined by linear temperature programing under an argon atmosphere to determine its mass loss kinetics. A simple kinetic model, called the first order pseudo single-component model, was used. The total weight-loss of each sample assumed to be in two periods, with each period corresponding to a one step decomposition of the PC-PET to volatiles. Three methods for determining the kinetic parameters by thermal gravimetric analysis were examined: differential analysis at a constant heating rate (differential), temperatures of a given conversion at a number of heating rates (isoconversional), and the maximum rate at multiple heating rates (peak temperature). The latter two multiple heating rates methods results were comparable to each other but they were not in agreement with the results from the differential method. The results of the differential method were insensitive to the heating rate and consistent with kinetics data reported in the literature for PET.     

Polysilsesquioxanes Containing Superparamagnetic Nanoclusters of Cobalt or Nickel

Theoretical and Experimental Chemistry - A method was developed for the synthesis of ion-coordinated polysilsesquioxanes (OSS-M) by reaction of amphiphilic carboxyl-containing oligosilsesquioxanes...     

Crystal growth,structure, and properties,of a new oxovanadium(IV) phosphate material, [H2en]4[V7P8O35(OH)6(H2O)]·3H2O prepared via a mild one step hydrothermal route

One new oxovanadium(IV) phosphate material, [H₂en]₄[V₇P₈O₃₅(OH)₆(H₂O)]·3H₂O was prepared utilizing a one step, mild hydrothermal route involving ethylenediamine as the reducing agent. The compound was structurally characterized by single crystal and powder X-ray diffraction methods and found to crystallize in the monoclinic space group C2/c. The temperature dependence of the magnetic susceptibility of was measured and found to be paramagnetic down to 2 K. The compound was further characterized by IR and UV–Vis spectroscopies.     

Columnar Liquid‐Crystalline Dinaphthoperylenetetracarboxdiimides

Although the double Friedel–Crafts acylation of arenes with ethyl chloroglyoxylate is hindered by the strongly deactivating effect of the first‐entering glyoxylic substituent, the double reaction is successful with the reactive arene perylene under long reaction times and with concomitant ester hydrolysis. The reaction is regiospecific, giving the 3,9‐regioisomer exclusively. This perylenylenediglyoxylic acid is condensed first with o‐bromophenylacetic acid and then with α‐branched alkylamines to yield the title compounds. Whilst the corresponding tetraalkyl esters only show monotropic mesophases, these diimides show enantiotropic columnar mesophases that can be maintained at room temperature if racemically branched alkyl chains of moderate size are used. A palladium‐induced C?C bond migration during the build‐up of the arene system leads to an isomeric side product of reduced symmetry that can be isolated by aggregation‐controlled chromatographic separation. The HOMO and LUMO energies of the title compounds are considerably higher than those of established perylenetetracarboxdiimides.     

13 C Saturation-Transfer Difference (STD)-NMR Experiments Using INEPT Polarization Transfer

Saturation-transfer difference (STD)-NMR spectroscopy has been widely used to screen potential ligands for binding to large receptor molecules. The STD-NMR experiment is typically based on a proton NMR spectrum, which can suffer from spectral overlap, leading to missing information in STD-based epitope mapping. Two-dimensional STD-NMR experiments can alleviate spectral overlap, but are time consuming. Here, we examine the feasibility of saturating protons in a receptor molecule and observing the STD effect on nearby carbon nuclei after transferring polarization from protons to carbons using the insensitive nuclei enhanced by polarization transfer (INEPT) pulse sequence. We show that under favorable conditions, a 1H→13C STD-INEPT experiment can give information similar to that obtained from a two-dimensional heteronuclear experiment, but in significantly less time. The STD-INEPT experiment could be especially useful when studying mixtures of ligands in which the peak positions in the proton and HSQC spectrum change significantly, and in particular, when using high-throughput, automated methods to analyze the data.     

A Dual Threat: Redox-Activity and Electronic Structures of Well-Defined Donor–Acceptor Fulleretic Covalent-Organic Materials

The effect of donor (D)–acceptor (A) alignment on the materials electronic structure was probed for the first time using novel purely organic porous crystalline materials with covalently bound two- and three-dimensional acceptors. The first studies towards estimation of charge transfer rates as a function of acceptor stacking are in line with the experimentally observed drastic, eight-fold conductivity enhancement. The first evaluation of redox behavior of buckyball- or tetracyanoquinodimethane-integrated crystalline was conducted. In parallel with tailoring the D-A alignment responsible for “static” changes in materials properties, an external stimulus was applied for “dynamic” control of the electronic profiles. Overall, the presented D–A strategic design, with stimuli-controlled electronic behavior, redox activity, and modularity could be used as a blueprint for the development of electroactive and conductive multidimensional and multifunctional crystalline porous materials.     

A category of kernels for equivariant factorizations,II: Further implications

We leverage the results of the prequel [8], in combination with a theorem of D. Orlov to create a categorical covering picture for factorizations. As applications, we provide a conjectural geometric framework to further understand M. Kontsevich's Homological Mirror Symmetry conjecture and obtain new cases of a conjecture of Orlov concerning the Rouquier dimension of the bounded derived category of coherent sheaves on a smooth variety.