An extremal problem concerning matrices of 0's and 1 's

We determine the smallest number f(n,k) such that every (0,1)-matrix of order n what zero main diagonal which has at least f(n,k) 1's contains an irreducible, principal submatrix of order K. We characterize those matrices with f(n,k)-1 l's having no irreducible, principal submatrix of order k     

Magnetic control of chemical transformations: application for programmed electrocatalysis and surface patterning

Lateral translocation of electrocatalyst-modified magnetic particles was achieved upon application of an external magnetic field. Programmed electrocatalytic reactions at different electrodes or different areas of an electrode were performed. The spatially controlled electrocatalytic reactions were exemplified with NADH electrocatalytic oxidation and with bioelectrocatalytic electrode patterning. The method will be particularly useful for programmed electrochemical reactions at interdigitated electrodes.     

Oxidopyrylium [5+2] cycloaddition chemistry: Historical perspective and recent advances (2008–2018)

The following review article provides an overview of oxidopyrylium [5+2] cycloaddition chemistry, with a particular emphasis placed on seminal historical developments and advancements made over the last decade. It is our hope this review serves as a valuable resource to those interested in the oxidopyrylium cycloaddition chemistry, and helps inspire future advancements.     

Attomole protein analysis by CIEF with LIF detection

We have coupled CIEF with an LIF detector that is based on a post‐column sheath flow cuvette. We employed Chromeo P503 as a fluorogenic reagent to label proteins before analysis. This reagent reacts with the ε‐amine of lysine residues, preserving the cationic nature of the residue; labeled proteins generate extremely sharp peaks in CIEF. A set of four standard proteins generated a linear relationship between migration time and pI. A protein homogenate prepared from a Barrett's esophagus cell line resolved over 100 components in a 40 min separation. Detection limits for Chromeo P503‐labeled β‐lactoglobulin were 5 amol injected into the capillary. Fluorescent impurities present in the ampholytes generated a large background signal that degraded the detection limit by four orders of magnitude compared with other forms of capillary electrophoresis with this detector.     

Modification of Electrical Activity of Grain Boundaries in EFG Silicon Under Influence of Hydrogen Plasma

We investigated an influence of hydrogen plasma treatment on electrical properties of shaped silicon polycrystals. Hydrogen penetration into polycrystalline silicon is demonstrated to depend on the state of the crystal (as-grown or annealed) and type of grain boundary (general or weakly deviated from special orientations). It is found that interaction of atomic hydrogen with grain boundaries can result not only in decrease of their electrical activity, but also in increase of potential barrier height at relatively high (more than 2 × 10¹⁸ cm^–2) doses of incorporated hydrogen. This phenomenon is explained by a phenomenological model which takes into account passivation of grain boundary dangling bonds and boron atoms in the bulk as two main mechanisms controlling hydrogenation effect.     

Superspace mechanics as the classical limit of superfield theory

The semi-classical superspace pseudomechanics of Casalbuoni and others is shown to be the classical limit of a scalar superfield theory by a WKB type of approximation. By avoiding second class constraints, the relationship between the mechanics and the field theory is clarified. The spin1/2sector is then examined to find the (semiclassical) WKB limit of the Dirac equation.