Effect of viscosity on internal waves from a source in a wall

The solution for a line source of oscillatory strength kept at the origin in a wall bounding a semi-infinite viscous imcompressible stratified fluid is presented in an integral form. The behaviour of the flow at far field and near field is studied by an asymptotic expansion procedure. The streamlines for different parameters are drawn and discussed. The real characteristic straight lines present in the inviscid problem are modified by the viscosity and the solutions obtained are valid even at the resonance frequency.     

Multiple ionic-plasmon resonances in naturally occurring multiwall nanotubes: infrared spectra of chrysotile asbestos

Chrysotile asbestos is formed by densely packed bundles of multiwall hollow nanotubes. Each wall in the nanotubes is a cylindrically wrapped layer of Mg(3)Si(2)O(5)(OH)(4). We show by experiment and theory that the infrared spectra of chrysotile present multiple ionic-plasmon resonances in the Si-O stretching bands. These collective charge excitations are universal features of the nanotubes that are obtained by cylindrically wrapping an anisotropic material. The multiple plasmons can be observed if the width of the resonances is sufficiently small as in chrysotile.     

Markov jump random c.d.f.’s and their posterior distributions

In this article we introduce the class of Markov jump random c.d.f.’s as a sub-class of the Q$Q$-Markov prior distributions studied in R.M. Balan [Q$Q$-Markov random probability measures and their posterior distributions, Stochastic Process. Appl. 109 (2004) 296–316]. Our main result states that if the prior distribution of a sample is a Markov jump process, then the posterior distribution can also be viewed as the distribution of a Markov jump process, whose transition mechanism and infinitesimal behavior have been updated in the light of the new data.     

Molecular Dynamics Simulations of Proteins with Chemically Modified Disulfide Bonds

Proteins that are used as therapeutic drugs act in the extracellular microenvironment. They usually have a small number of intramolecular disulfide bonds to help maintain their tertiary structure in the vascular circulation. In general, most cysteine residues are part of a disulfide bond with free sulfhydrals being uncommon. We have studied whether the site-specific chemical reduction of disulfides and the incorporation of a 3-carbon methylene bridge between the cysteines in interferon-α 2a would change the structure of this protein. Bridging of both of the disulfide bonds of interferon-α 2a was studied using two different molecular simulation protocols: (1) molecular dynamics, and (2) stochastic dynamics. We have shown that the disulfide bonds in interferon-α 2a can be reduced and chemically modified without significantly altering the tertiary structure of the protein. This offers the novel possibility of chemically modifying therapeutically important proteins without affecting their biological properties.     

Histamine detection using functionalized porphyrin as electrochemical mediator

This study reports on deposition of asymmetrical substituted meso-phenyl porphyrin, 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin (CPTPP) thin films by matrix-assisted pulsed laser evaporation (MAPLE) on screen-printed electrodes, aiming for histamine detection. Raman spectrometry confirmed that CPTPP chemical structure was preserved in MAPLE-deposited thin films at 200 mJ/cm² laser fluence. Atomic force microscopy topography revealed that MAPLE-deposited thin films have a better coverage on the working electrode made of carbon compared to the ones obtained by dropcasting. Cyclic voltammetry demonstrated that CPTPP is an appropriate mediator for histamine detection in trichloroacetic acid solution. We proved that MAPLE serves as a soft technique in fabrication of porphyrin thin films and patterns.