Electrical and optical properties of amorphous semiconducting GeSe and GeSbSe films

The electrical activation energy and optical band-gap of GeSe and GeSbSe thin films prepared by flash evaporation on to glass substrates have been determined. The conductivities of the films were found to be given by Image , the activation energy Ea being 0.53 eV and 0.40 eV for GeSe and GeSbSe respectively. The optical absorption constant α near the absorption edge could be described by Image from which the optical band-gaps E0 were found to be 1.01 eV for GeSe and 0.67 eV for GeSbSe at 300°K. At 110°K the corresponding values of E0 were 1.07 eV and 0.735 eV respectively. The significance of these values is discussed in relation to those of other amorphous semiconductors

Tetracycline hydrochloride (TCH)-loaded drug carrier based on PLA:PCL nanofibre mats: experimental characterisation and release kinetics modelling

The experimental characterisation of electrospun poly(lactic acid) (PLA): poly(e-caprolactone) (PCL) as drug carriers, at five blend ratios from 1:0, 3:1, 1:1, 1:3 and 0:1, was holistically investigated in terms of their morphological structures, crystallinity levels and thermal properties. A widely used antibiotic tetracycline hydrochloride (TCH) was loaded to prepared fibrous mats at TCH concentrations of 1 and 5 wt%. The additional TCH into PLA: PCL better facilitates the reduction of fibre diameter than polymer blends. Increasing the TCH concentration from 1 to 5 wt% was found to result in only a modest decrease in the crystallinity level, but a significant increase in the crystallisation temperature (Tc) for PLA within PLA: PCL blends. The infrared spectra of fibre mats confirm the successful TCH encapsulation into fibrous networks. The first order and Zeng models for drug release kinetics were in better agreement with experimental release data, indicating the release acceleration of TCH with increasing its concentration. In a typical case of PLA: PCL (1:1) loaded with 5 wt% TCH, the fibre mats apparently demonstrate more wrinkled and floppy structures and increased fibre diameters and decreased inter-fibrous spaces after 7-day in vitro fibre degradation, as opposed to those obtained after 3-h degradation