Hydrogen-induced stress relaxation in thin Pd films: influence of carbon implementation

The influence of carbon impurities on mechanical properties of thin Pd film in the process of hydride formation and its disintegration has been investigated "in situ" by means of atomic force microscopy (AFM). Pd interaction with hydrogen leads to the formation of hydride PdHx, if critical conditions of pressure and temperature are reached (equilibrium hydrogen pressure over PdHx at 298 K is approximately 1 kPa). The lattice constant of PdHx is larger than that of the original metal, and the hydride formation generates high stress within the film. As a consequence, the reversible formation of well organized mesoscopic protrusions on the film surface is observed. In this paper, we focus our investigation on the mechanical response which occurs when, prior to hydride generation, carbon atoms are incorporated into the bulk of the film. The systems characterized by carbon incorporation from the two opposite sides of thin palladium film (HOPG substrate and hydrocarbon fragments deposit from a gas-phase reached by preadsorption of ethylene) are compared. For both cases the mechanism of mechanical response is the same, but very different from that registered for pure thin palladium film. Carbon impurities induce, during PdHx decomposition, creation of an organized network of cracks which divides the continuous film into separated domains. The mechanisms of carbon introduction occurring in both cases have been proposed.     

Chemical transformations of alcohols sampled with the use of adsorptive enrichment on the carbon adsorbent traps followed by thermal desorption

Graphitized carbons, Carbopack X, Carbograph 5TD and Carbotrap B, used to enrich samples of C(3)-C(4) alcohols determined in the atmospheric air produce experimental artefacts. After thermal desorption, recoveries for alcohols are much smaller than unity with a concomitant appearance of aldehydes and ketones on chromatograms. Obviously, the adsorbents studied cannot be recommended for analysis of alcohols, ketones and aldehydes in the atmosphere. Polymeric adsorbents, Tenax TA and Chromosorb 106, do not exhibit such oxidative properties.     

Development of Adenosine Deaminase-Specific IgY Antibodies: Diagnostic and Inhibitory Application

Adenosine deaminase (ADA) is currently used as a diagnostic marker for tuberculous pleuritis. Although ADA has been suggested as a potential marker for several types of cancer, the importance of each of ADA isoforms as well as their levels and enzymatic activities in tumors need to be further investigated. Herein we developed avian immunoglobulin Y highly specific to human ADA via hens immunization with calf adenosine deaminase. The obtained antibodies were used for the development of a sensitive double-egg yolk immunoglobulin (IgY) sandwich ELISA assay with an ADA detection limit of 0.5 ng/ml and a linearity range of up to 10 ng/ml. Specific, affinity-purified IgYs were able to recognize human recombinant ADA and ADA present in human cancer cell lines. In addition, antigen-specific IgY antibodies were able to inhibit catalytic activity of calf ADA with an IC₅₀ value of 47.48 nM. We showed that generated IgY antibodies may be useful for ADA detection, thus acting as a diagnostic agent in immunoenzymatic assays.     

Spectroscopic Characterization of i-motif Forming c-myc Derived Sequences Double-Labeled with Pyrene

In current studies we use the oligonucleotides based on c-myc sequence: CCC CAC CCT CCC CAC CCT CCC C (cmyc22) and CCC CAC CCT CCC CAC CCT CCC CA (cmyc22A) functionalized by pyrene moieties at both termini. Results of the circular dichroism (CD), UV absorption melting experiments, and steady-state fluorescence measurements of pyrene-modified i-motifs as well as their unlabeled precursors are presented and discussed here. The pyrene labels have a remarkable influence on i-motif stability which was deduced from CD spectra and confirmed by UV melting experiments. Both probes emit fluorescence band of pyrene monomer with intensity decreasing upon pH lowering.     

Synthesis of Some Quaternary N-(1,4-anhydro-5-deoxy-D,L-ribitol-5-yl)ammonium Salts

The successful removal of the isopropylidene-protecting group from 1,4-anhydro-2,3-O-isopropylidene-5-O-tosyl-D,L-ribitol and from quaternary N-(1,4-anhydro-5-deoxy-2,3-O-isopropylidene-D,L-ribitol-5-yl)ammonium salts is reported. The structures of all isolates were determined by spectral analysis, including extensive 2-D NMR analyses. Single-crystal x-ray diffractions of 1,4-anhydro-5-O-tosyl-D,L-ribitol and its 2,3-O-isopropylidene derivatives are reported.     

Small amplitude chimeras for coupled clocks

Nonlinear Dynamics - We report the arise of small amplitude chimera states in three coupled pendulum clocks suspended on an oscillating base. Two types of chimeras are identified and described by...     

Classification of amino acids and oligopeptides with the use of multi-mode chemical images obtained with ion selective electrode array

The analysis of amino acids and oligopeptides as important bioanalytes is a significant task in medical diagnostics and proteomic research and currently it is based on chromatographic and electrophoretic methods. In this paper, an approach based on sensor array coupled with titration is proposed for effective recognition of 5 amino acids and 4 oligopeptides. It is shown, that the increase of information gained during measurements of sensors’ signals in various pH allows for capturing more data on interaction of amino acids and oligopeptides with various polymeric membranes of potentiometric electrodes used in the array, and that leads to the lowering of classification errors in partial least squares analysis.     

Optically Active T-Butylphenylphosphinothioic Acid: Synthesis,Selected Structural Studies and Applications as a Chiral Solvating Agent

Abstract

Synthesis, structural studies and the use of the (?)-(S)- and (+)-(R) enantiomers of t-butylphenylphosphinothioic acid as a chiral solvating agent for the determination of enantiomeric purity is discussed. Systems that are the most extensively studied are emphasized.