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This paper presents the characteristics of magnesium aluminium silicate-gentamicin complexes for drug delivery systems. The work describes the results of studies on the successful introduction of gentamicin (an aminoglycoside antibiotic) into the interlayers of smectite clay and examines the possible use of intercalated smectite as a carrier for sustained drug release. Characterisation of magnesium aluminium silicate-gentamicin complexes was carried out by means of X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis and scanning electron microscopy with EDX analysis. The possibility of using the gentamicin intercalated smectite as a carrier for sustained release of the drug was investigated during in vitro study, in which the release rate of gentamicin from the smectite clay matrix was monitored based on absorption at 330 nm using a UV-Vis spectrometer and the kinetic of drug release was evaluated based on the zero-order, first-order, Higuchi and Korsmeyer-Peppas models. The results confirmed the efficiency of intercalation and indicate the potential for introducing gentamicin into the interlayer space of montmorillonite. Accordingly, the obtained material may thus be used as a drug carrier in modulated drug delivery systems. [ABSTRACT FROM AUTHOR]

Scintillator materials are widely used in X-ray medical imaging detector applications, coupled with available photoreceptors like radiographic film or photoreceptors suitable for digital imaging like a-Si, charge-coupled devises (CCD), complementary metal-oxide-semiconductors (CMOS) and GaAs). In addition, scintillators can be utilized in non-medical imaging detectors such as industrial detectors for non-destructive testing (NDT) and detectors used for security purposes (i.e. airport luggage control). Image quality and dose burden in the above applications is associated with the amount of optical photons escaping the scintillator as well as the amount of optical photons captured by the photoreceptor. The former is characterized by the scintillator efficiency and the latter by the spectral matching between the emission spectrum of the scintillator and the spectral response of the photoreceptor. Recently, a scintillator material, europium-activated lutetium oxide (LuO:Eu), has shown improved scintillating properties. LuO:Eu samples of compact nanocrystalline non-agglomerated powder were developed in our laboratory using homogeneous precipitation from a water-toluene solution in the presence of polyvinyl alcohol as a surfactant. In order to test their light-emission properties, experimental measurements under the excitation of X-ray spectra with X-ray tube voltages between 50 kVp and 140 kVp were performed. This range of applied voltages is appropriate for X-ray radiology, NDT and security applications. LuO:Eu was evaluated with respect to output yield and spectral compatibility of digital imaging photoreceptors (CCD-based, CMOS-based, amorphous silicon a:Si flat panels, ES20 and GaAs). High light yield and spectral compatibility increase the performance of the medical detector and reduce the dose burden to the personnel involved. In addition a theoretical model was used to determine the values for the LuO:Eu optical photon light propagation parameters. The inverse diffusion length was found to be equal to 33 cm/g. In addition LuO:Eu was found to match well with several photoreceptors capable of digital imaging (i.e. GaAs). [ABSTRACT FROM AUTHOR]

Powders and thin films of nanocrystalline yttrium disilicate (Y2Si2O7) doped with Ce3+ have been prepared by a sol–gel method. Structure and morphology of the synthesised samples have been determined and spectroscopic properties compared. The triclinic α-Y2Si2O7 form (space group P 1-) for the powders annealed between 1000°C and 1200°C has been found. A total conversion into a thortveitite-type monoclinic β-Y2Si2O7 polymorph after annealing of powder samples at 1400°C (space group C2/m) has been observed. In the case of films even at 1300°C the basically pure triclinic α-Y2Si2O7 phase was observed with luminescent spectroscopy. The influence of grain size, controlled by thermal treatment, on the structure and luminescence properties of the fabricated materials are presented and discussed. [ABSTRACT FROM AUTHOR]

The study concerned with the current work is to provide a comparative investigation of the detective quantum efficiency (DQE) of Lu2O3:Eu phosphor screens, prepared with different grain shape/size grains, specifically spherical grains, with sizes 50 nm, 200 nm, and 5 µm and two screens with rod-like shape grains and sizes 500 nm and 1-8 µm. The phosphors were deposited by the sedimentation method. It was found that the influence of the grains shape on image quality is more important than the grain size. The rod-like grains show higher noise levels, at low frequencies. The influence of grains size, between 50 nm, 200 nm, and 5 µm, is negligible on the normalize noise power spectrum (NNPS) at higher spatial frequencies due to structural non-uniformities. The spherical grains exhibited higher DQE values. [ABSTRACT FROM AUTHOR]