Non-commutative Łukasiewicz propositional logic

The non-commutative counterpart of the well-known Łukasiewicz propositional logic is developed, in strong connection with the algebraic theory of psMV-algebras. An extension by a new unary logical connective is also considered and a stronger completeness result is proved for this system.     

Mössbauer investigations of the Fe−Cu−Mn catalysts for Fischer-Tropsch synthesis

In the selective process of the syngas conversion to synthetic gasoline a bifunctional catalytic system has to be used. It was obtained by combination a Fischer-Tropsch catalyst with the HZSM-5 zeolite. The phase compositions of the precursor and the fresh catalyst were established as well as the optimum thermal treatment. The catalyst was reduced in pure H₂ or in a H₂+CO mixture. The influence of the reduction and reaction conditions on the catalyst structure was investigated.     

63Cu NMR evidence for enhanced antiferromagnetic correlations around Zn impurities in YBa2Cu3O6.7

Doping the high- T(c) superconductor YBa2Cu3O6.7 with 1.5% of nonmagnetic Zn impurities in CuO2 planes is shown to produce a considerable broadening of 63Cu NMR spectra, as well as an increase of low-energy magnetic fluctuations detected in 63Cu spin-lattice relaxation measurements. A model-independent analysis demonstrates that these effects are due to the development of staggered magnetic moments on many Cu sites around each Zn and that the Zn-induced moment in the bulk susceptibility might be explained by this staggered magnetization. Several implications of these enhanced antiferromagnetic correlations are discussed.     

Metric and multidimensional scaling: efficient tools for clustering molecular conformations

The application of metric and multidimensional scaling to conformer ensembles was demonstrated in this work. An automated process was devised to cluster and assign group memberships and cluster representatives. The method allows rapid clustering, leading to intuitive results that can be visually inspected. Multidimensional scaling was found to be superior to metric scaling for clustering conformers. The performance of different hierarchical clustering algorithms was compared using multidimensional plots, and the group average method was found to perform best.     

Clustering of catalytic nanocompartments for enhancing an extracellular non-native cascade reaction

Compartmentalization is fundamental in nature, where the spatial segregation of biochemical reactions within and between cells ensures optimal conditions for the regulation of cascade reactions. While the distance between compartments or their interaction are essential parameters supporting the efficiency of bio-reactions, so far they have not been exploited to regulate cascade reactions between bioinspired catalytic nanocompartments. Here, we generate individual catalytic nanocompartments (CNCs) by encapsulating within polymersomes or attaching to their surface enzymes involved in a cascade reaction and then, tether the polymersomes together into clusters. By conjugating complementary DNA strands to the polymersomes'' surface, DNA hybridization drove the clusterization process of enzyme-loaded polymersomes and controlled the distance between the respective catalytic nanocompartments. Owing to the close proximity of CNCs within clusters and the overall stability of the cluster architecture, the cascade reaction between spatially segregated enzymes was significantly more efficient than when the catalytic nanocompartments were not linked together by DNA duplexes. Additionally, residual DNA single strands that were not engaged in clustering, allowed for an interaction of the clusters with the cell surface as evidenced by A549 cells, where clusters decorating the surface endowed the cells with a non-native enzymatic cascade. The self-organization into clusters of catalytic nanocompartments confining different enzymes of a cascade reaction allows for a distance control of the reaction spaces which opens new avenues for highly efficient applications in domains such as catalysis or nanomedicine.

Compartmentalization is fundamental in nature, where the spatial segregation of biochemical reactions within and between cells ensures optimal conditions for the regulation of cascade reactions.     

Design and evaluation of a new Peltier-cooled laser ablation cell with on-sample temperature control

A new custom-built Peltier-cooled laser ablation cell is described. The proposed cryogenic cell combines a small internal volume (20 cm³) with a unique and reliable on-sample temperature control. The use of a flexible temperature sensor, directly located on the sample surface, ensures a rigorous sample temperature control throughout the entire analysis time and allows instant response to any possible fluctuation. In this way sample integrity and, therefore, reproducibility can be guaranteed during the ablation. The refrigeration of the proposed cryogenic cell combines an internal refrigeration system, controlled by a sensitive thermocouple, with an external refrigeration system. Cooling of the sample is directly carried out by 8 small (1 cm × 1 cm) Peltier elements placed in a circular arrangement in the base of the cell. These Peltier elements are located below a copper plate where the sample is placed. Due to the small size of the cooling electronics and their circular allocation it was possible to maintain a peephole under the sample for illumination allowing a much better visualization of the sample, a factor especially important when working with structurally complex tissue sections. The analytical performance of the cryogenic cell was studied using a glass reference material (SRM NIST 612) at room temperature and at −20 °C. The proposed cell design shows a reasonable signal washout (signal decay within less than 10 s to background level), high sensitivity and good signal stability (in the range 6.6–11.7%). Furthermore, high precision (0.4–2.6%) and accuracy (0.3–3.9%) in the isotope ratio measurements were also observed operating the cell both at room temperature and at −20 °C. Finally, experimental results obtained for the cell application to qualitative elemental imaging of structurally complex tissue samples (e.g. eye sections from a native frozen porcine eye and fresh flower leaves) demonstrate that working in cryogenic conditions is critical in such type of direct sample analysis.     

Expanding the structural landscape of niclosamide: a high Z′ polymorph,two new solvates and monohydrate HA

Three new crystalline phases are reported for the drug niclosamide [5‐chloro‐N‐(2‐chloro‐4‐nitrophenyl)‐2‐hydroxybenzamide], C₁₃H₈Cl₂N₂O₄. A new high‐Z′ polymorph (denoted Form II) is described, with four molecules in the asymmetric unit in the space group P2/n. The structure exhibits pseudosymmetry, including local translations and screw‐type operations. The niclosamide molecules are linked by O—H...O hydrogen bonds into chains, and the chains are packed so that the molecules form face‐to‐face (stacking) and end‐to‐end interactions within layers perpendicular to the chains. There are two different layer arrangements, giving a structure that is relatively complex. In the acetone and acetonitrile solvates, the incorporated solvent molecules accept hydrogen bonds from the OH groups of niclosamide, and the niclosamide molecules are stacked in a face‐to‐face manner. In the acetone solvate, C₁₃H₈Cl₂N₂O₄·C₃H₆O, V‐shaped arrangements are formed in which the nitrobenzene ends of the niclosamide molecules are brought into face‐to‐face contact. In the acetonitrile solvate, C₁₃H₈Cl₂N₂O₄·CH₃CN, stacking occurs by translation along a short axis (ca 3.8 Å) and the crystals are frequently observed to be twinned by twofold rotation around that axis. The acetonitrile molecules occupy channels in the structure. A complete structure is provided for niclosamide monohydrate, C₁₃H₈Cl₂N₂O₄·H₂O, polymorph H_A, obtained by Rietveld refinement against laboratory powder X‐ray diffraction data. It has been suggested that this compound is related to the methanol solvate of niclosamide [Harriss, Wilson & Radosevljevic Evans (2014). Acta Cryst. C 70 , 758–763], but it is found that the two are not fully isostructural: they contain isostructural two‐dimensional layers, but the layers are arranged differently in the two structures. This suggests that H_A may have the potential for polytypism, and features in the Rietveld difference curve indicate that a polytype fully isostructural with the methanol solvate might be present.     

Thermal stability of new biologic active copper(II) complexes with 5,6-dimethylbenzimidazole

Three new coordinative compounds that contain mixed ligands (5,6-dimethylbenzimidazole and acrylato anion) were synthesized and characterized. The features of complexes have been assigned from microanalytical, IR, UV–Vis and EPR spectra as well as thermal analysis. IR data are in accordance with unidentate nature of 5,6-dimethylbenzimidazole while the acrilato ion acts as uni- or bidentate ligand. The electronic spectra display the characteristic pattern of square pyramidal or octahedral stereochemistry, which were confirmed by the EPR spectra. Antibacterial and antifungal activities of the complexes have been determined in vitro, against various Gram-negative and Gram-positive bacteria and fungi. The tested complexes exhibited different spectra of antimicrobial activity and inhibited the microbial ability to colonize the inert surfaces, acting as potential anti-adherence and biofilm-controlling agents. Thermal decomposition evidenced several well-defined steps as dehydration (complex 2), 5,6-dimethylbenzimidazole molecule release (all complexes) and the acrylate decomposition in carbonate (complex 3). The final residue is in all cases copper (II) oxide.     

Electron-deficient adduct site in the ring opening of methylcyclopentane (MCP) on tungsten-oxide-supported Pt,Ir and Pt–Ir catalysts

The activities of Pt/WO₂, Ir/WO₂ and Pt–Ir/WO₂ toward the conversion of methylcyclopentane (MCP) were investigated. The catalysts were prepared using impregnation and co-impregnation methods and were characterized by SEM, XRD, N₂-sorption and TEM investigations. The most active catalyst toward the conversion of MCP, irrespective of the temperature, was Ir/WO₂. The order of the reactivity was Ir/WO₂ > Pt–Ir/WO₂ > Pt/WO₂. Strong metal–support interactions (SMSI) were observed for all the catalysts over the entire investigated temperature range. At 400 °C, the Pt and Pt–Ir showed 100% selectivity toward ring-enlargement reactions associated with the presence of electron-deficient adduct sites on the reducible acidic WO₂ support. Ring opening occurred over all the catalysts in three positions, resulting in the formation of 2-methylpentane (2-MP), 3-methylpentane (3-MP), and n-hexane (n-H). Difficulty in breaking the secondary – tertiary carbon bonds was observed predominantly on the Ir catalyst, which opens the MCP ring via a selective mechanism.