Polymer Micelles for Delayed Release of Therapeutics from Drug‐Releasing Surfaces with Nanotubular Structures

A new approach to engineer a local drug delivery system with delayed release using nanostructured surface with nanotube arrays is presented. TNT arrays electrochemically generated on a titanium surface are used as a model substrate. Polymer micelles as drug carriers encapsulated with drug are loaded at the bottom of the TNT structure and their delayed release is obtained by loading blank micelles (without drug) on the top. The delayed and time‐controlled drug release is successfully demonstrated by controlling the ratio of blank and drug loaded‐micelles. The concept is verified using four different polymer micelles (regular and inverted) loaded with water‐insoluble (indomethacin) and water‐soluble drugs (gentamicin).

     

The DESTIN: Preservice Teachers' Drawings of the Ideal Elementary Science Teacher

The aim of this study is to report findings from the Drawing‐Elementary‐Science‐Teacher‐Ideal‐Not, or the DESTIN procedure. The study utilizes a simple drawing procedure accompanied by a narrative and discussion for understanding preservice teachers' images of science, science teaching, and the science teacher. Ninety drawings from two sections of an elementary science methods course were analyzed. Looking at the pre‐drawings from the beginning of the semester and post‐drawings done at the end of the semester, the findings relate the value of using drawings in teacher education and the usefulness of this procedure to promote discussions about science teaching, the construction of new images and practices for teaching elementary science, and teacher identity. The DESTIN procedure has potential as a productive activity for teacher education and long‐term professional development by making more explicit teachers' views of science teaching and learning and their past experiences as science learners.     

Shehu Transform: Extension to Distributions and Measures

This paper improves the computational aspect of the Shehu transform. An inversion formula is given. Finally the Shehu transform is extended to distributions and measures.     

Diffraction tomography: a geometrical distortion free procedure

Ductal echography (DE) is a recent anatomically-led method of investigation of internal mammary structures that provides direct observation of ductolobular structures in mammary lobes. Indeed, breast cancer initiates from the epithelium (hypoechogenic) and develops first in ductolobular structures. Our research aims at developing an ultrasonic scanner (hemispherical antenna) that will allow three-dimensional measurement of the field diffracted by the gland. The present reconstruction procedure is an alternative solution to the standard elliptic back-projection (EBP) technique based on the Born approximation (weak scattering assumption). The latter implicitly assumes that the sound speed is (almost) constant within the breast. This unrealistic a priori is inconsistent with our heterogeneous media characterization purpose, and leads both to geometrical distortion in the reconstruction and to poor focusing of the backpropagated waves (low contrast imaging). However, the EBP technique retains a two-fold advantage: firstly it does not make any other assumption concerning the distribution of mechanical parameters apart from low gradients. Secondly, it shows great robustness, a high resolving power, and is easy to implement. Thus, in order to account for strong wavefront distortions, we integrate temporal compensation of the scattered signals acquired into the scattering EBP technique. The adjustment relies on a time of flight estimation based on a "layer stripping" approach. Numerical tests based on finite difference time domain simulations of data scattered by a random tissue-like phantom are proposed.     

Antimicrobial pentacyclic triterpenes and glycosides from the stem bark of Cussonia bancoensis

Abstract

The stem bark of Cussonia bancoensis is used traditionally for the treatment of different types of infection and pain. A bioassay guided fractionation of the methanol stem bark extract led to the isolation of five pentacyclic triterpenes and glycosides identified based on spectroscopic data as 23-hydroxyursolic acid (CB1), hederagenin (CB2), 3-O-α-L-arabinopyranosyl-echinocystic acid (CB3), 3-O-α-L-arabinopyranosyl- oleanolic acid (CB4) and 3-O-α-L-arabinopyranosyl-ursolic acid (CB5). CB2 - CB5 are being reported for the first time from this species. The compounds were evaluated for antimicrobial activity against ten microorganisms using the HT-SPOTi method. CB3 demonstrated remarkable antimicrobial activity against S. aureus, S. pyogens, E. faecalis, S. typhi and C. albicans at MICs between 3.12 and 12.5?µg/mL. Among the studied compounds, it was observed that hydroxylation of position C-16 of the oleanane skeleton may enhance antimicrobial activity. This study gives insight into the anti-infective constituents of the stem bark of C. bancoensis and justifies its use in ethnomedicine.     

Invariance analysis and reduction of discrete Painlevé equations

The construction and role of symmetries for difference equations have been established, relatively, recently. In this paper, a symmetry analysis and reductions of the discrete Painlevé equations are considered. We assume that the characteristics of the ‘vector fields’ have a particular dependence since the general form lead to cumbersome calculations. Where possible, these symmetries are used to construct exact solutions in some cases.     

Photostimulated attenuation of hypersound in superlattices

Photostimulated attenuation of hypersound in semiconductor superlattices has been investigated theoretically. It is shown that the attenuation coefficient depends on the phonon wave vectorqin an oscillatory manner and that from this oscillation the band width Δ of the superlattice can be found.     

Rectification in Chiral Carbon Nanotubes with Hot Electron Injection

Journal of Experimental and Theoretical Physics - The novel effect of direct current generation by carbon nanotubes with hot electron injection which may arise due to an electromagnetic radiation...