M. Sajjia

Effect of poly ethylene glycol on the mechanical and thermal properties of bioactive Poly (ε–caprolactone) melt extrudates for pharmaceutical applications

This paper investigates the effects of polyethylene glycol (PEG), on the mechanical and thermal properties of nalidixic acid/poly ε-caprolactone (NA)/PCL blends prepared by hot melt extrusion. The blends were characterized by tensile and flexural analysis, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. Results show that loading PEG in the PCL had a detrimental effect on the tensile strength and toughness of the blends, reducing them by 20-40%. The partial miscibility of the PCL-PEG system, causes an increase in Tg. While increases in the crystallinity is attributed to the plasticisation effect of PEG and the nucleation effect of NA. The average crystal size increased by 8% upon PEG addition. Experimental data indicated that the addition of NA caused loss of the tensile strength and toughness of PCL. Thermal analysis of the PCL showed that on addition of the thermally unstable NA, thermal degradation occurred early and was autocatalytic. However, the NA did benefit from the heat shielding provided by the PCL matrix resulting in more thermally stable NA particles.

Materials in PEM Fuel Cells

Tremendous efforts have been made in the last few decades to develop new energy sources that can replace the conventional power sources which relay on fossil resources. Among the different alternative power sources, the Proton Exchange Membrane Fuel Cell (PEMFC) is considered one of the most promising alternative clean power generators, since it offer the possibility of zero-emission by converting the chemical energy stored in hydrogen fuel directly into electricity with water as the only by-product.

Mechanistic modelling of industrial-scale roller compactor ‘Freund TF-MINI model’

Abstract A pharmaceutical roller compaction process was modelled using the Johanson powder mechanics model, which may be employed to achieve desired process performance. Mathematical modelling of the compaction of microcrystalline cellulose (PH102) was used to determine optimal process conditions for an industrial scale roll compactor (Freund, Model TF-MINI). The critical process parameters investigated were screw speed and roll pressure, while the rolls were kept at constant speed and the roll gap as variable. The roll-compacted ribbon density was considered the quality attribute of interest, as it is directly linked to the granule properties, particle size distribution and tablet mechanical properties. Experimental process data were used for model calibration and validation. This was followed by utilisation of the predictive capability of the model to achieve desired process performance of the compactor. The model findings indicated that the developed mechanistic model for the roller compactor can provide a design space to correlate the process parameters and materials properties to the critical quality attributes of granules which would be useful for implementation of Quality-by-Design paradigm in pharmaceutical manufacturing.

Production and Treatment of Porous Glass Materials for Advanced Usage

Porous glass is derived from glass that is heat treated to form two interconnecting phases: a silica-rich phase, and an alkali-rich borate phase. The heat-treated glass is then leached selectively to remove one of the phases. The heat-treatment step and leaching conditions can be adjusted to achieve the desired pore size, pore volume, and surface area. This glass has an interconnected pore structure with a uniform pore distribution. Therefore, porous glass based on the sodium borosilicate system which is widely known to undergo amorphous phase separation can be tailor-made to required specifications, thus offering flexibility in terms of end applications.

Mechanics and Computational Modeling of Pharmaceutical Tabletting Process

Tabletting is a cheap, but complicated, manufacturing process which is widely used in the pharma sector to produce pharmaceutical tablets as the most common form of solid dosage. The tabletting process is associated with many complex phenomena that may lead to undesirable tablet defects. Successful tabletting is very challenging and requires a sound knowledge of the powder behavior during compaction.

Properties of Glass Materials

Properties of glasses like the density, viscosity, thermal expansion coefficient, chemical durability, electrical resistivity, and refractive index, as a function of bulk composition define the common structure models. The concepts of phase separation, bridging and non-bridging oxygen formation, network structures, and elemental effect on composition properties further explain the characteristic of a particular glass. Thermal history has a profound effect on density and viscosity of a vitreous glass. Therefore, it is essential to fully understand a glass composition and thermal history, to produce glasses of desirable mechanical, optical, and electrical properties for a particular application.

Metallic Thin-Walled Tubes for Crashworthiness Applications: A Reference Guide

Over the past several decades, thin-walled (TW) metallic tubes have been widely used in energy absorbing structures to alleviate the detrimental effects of an impact loading and enhance the crashworthiness performance of a vehicle. In this article, based on a broad survey of the literature, a comprehensive overview of the recent developments in the area of crashworthiness performance of TW tubes is given with a special focus on the topics that emerged in the last 10 years such as crashworthiness optimization design and energy absorbing responses of unconventional TW components including multicells tubes, and functionally graded thickness tubes. Due to the huge number of studies that analyzed and assessed the energy absorption behavior of various TW components, this article presents only a review of the crashworthiness behavior of metallic hollow structures under various loading conditions.

Transparent Conductive Oxides Thin Films for Radio Frequency Attenuation

A great interest has arisen in technologies that use radio frequency. Not limited to the sensitive electrical devices, radio frequency is the key for all applications that employ transmission of information. This has brought different kinds of fear on what effects these frequencies could have on human beings. Radio frequency shielding is employed where there is a need for that whether as a precaution or a requirement. In this article, transparent conductive oxides (TCOs) in the form of thin films are reviewed as a type of material known to have the best combination between good conductivity and optical transparency. The physical properties of TCOs were thoroughly discussed to address a good understanding for the radio frequency attenuation process.