Characterization of the mechanism of interaction in ibuprofen-Eudragit RL100 coevaporates

The present study is a preliminary exploration of the affinity between a carboxylic model drug, the nonsteroidal antiinflammatory agent ibuprofen (IBU) and Eudragit RL100 (RL) polymer. Due to the presence of a variable amount of quaternary ammonium groups in this matrix, physical and chemical interaction with the carboxylic drug can occur, which reinforces its scant mechanical dispersion in the polymer network and can ultimately affect its release profile in vitro and in vivo. To study these aspects, IBU was mixed at increasing weight ratios and in different chemical forms (free acid, sodium salt, and n-butyl ester), to investigate further the role of the carboxylic group in the interaction with the RL polymer. Therefore, IBU-RL solid dispersions (coevaporates) were obtained and fully characterized in the solid state through spectroscopic, calorimetric, and x-ray diffractometric analyses. The in vitro release pattern of the drug, in the different chemical states, was studied for the coevaporates, compared with drug-RL physical mixtures, along with drug adsorption profiles from aqueous solutions on the surface of the polymer granules.     

Raman spectra of virgin and damaged graphite edge planes

First-order Raman spectra of virgin and ion irradiated highly oriented pyrolytic graphite were performed along the basal and edge planes. Ion irradiation was performed in the low fluence regime (≈ 10¹²–10¹³ ions cm⁻²) using a 400 keV Ar⁺ beam in order to a introduce controlled amount of defects in the structure. Virgin edge Raman spectra reveal the presence of a 1351 cm⁻¹ structure (D^*) shifted 10 cm⁻¹ away from the disorder induced D-line found upon irradiating or grinding the graphite surface.The 1351 cm⁻¹ D^* structure is then considered as the feature coming from the rupture of the D_6h⁴ space group symmetry. A comparison between D^* and the classical 1360 cm⁻¹ D-line is discussed in terms of induced disorder.     

Radial junctions formed by conformal chemical doping for innovative hole-based solar cells

In this paper an innovative approach for Si solar cells based on radial junctions is presented. It consists of fabricating the junction in quasi one-dimensional structures like holes. The hole-based architecture, while maintaining the decoupling between the light absorption and the electrical collection typical of the more common wires and rods, ensures more robustness, numerous waveguide coupling modes and possibility to form non-conformal top contact. Nanosizes also provide the possibility to tune the band gap by quantum effects. Doping of the nanoholes, like in the case of nanowires, presents critical issues like conformality and control of the dopant dose and junction depth at nanometric level. We propose to dope the nanoholes by using a chemical method based on the use of a dopant containing molecules dispersed in solution. We apply the procedure on an array of holes of micrometric sizes fabricated to test and study the method and to properly scale it down and implement it on the nanostructures. Results show that the method provides junction depths in the nm scale with dopant peak concentrations as high as 10¹⁹ cm^?3 and that the doping is conformal on the vertical surfaces of the hole.     

IMP2, a nuclear gene controlling the mitochondrial dependence of galactose, maltose and raffinose utilization in Saccharomyces cerevisiae.

The IMP2 gene of Saccharomyces cerevisiae is involved in the nucleo-mitochondrial control of maltose, galactose and raffinose utilization as shown by the inability of imp2 mutants to grow on these carbon sources in respiratory-deficient conditions or in the presence of ethidium bromide and erythromycin. The negative phenotype cannot be scored in the presence of inhibitors of respiration and oxidative phosphorylation, indicating that the role of the mitochondria in the utilization of the above-mentioned carbon sources in imp2 mutants is not at the energetical level. Mutations in the IMP2 gene also confer many phenotypic alterations in respiratory-sufficient conditions, e.g. leaky phenotype on oxidizable carbon sources, sensitivity to heat shock and sporulation deficiency. The IMP2 gene has been cloned, sequenced and disrupted. The phenotype of null imp2 mutants is indistinguishable from that of the originally isolated mutant.