Development of Phosphate Based Glass Scaffolds for the Repair of Craniofacial Bone

Degradable phosphate-based glasses have been known to have many potential properties to work as biomaterials for bone repair clinical applications. Although several studies were performed on different compositions to investigate the most appropriate glass formula, no specific formula was found to be the most favourable for clinical application. The main aim of this thesis was to fabricate and biologically assess phosphate glass scaffold made from specific elements known for their potential in promoting bone growth. To achieve this, primary studies were done on four different compositions of both zinc and strontium phosphate-based glass discs. The next study was to further investigate the best two zinc and strontium glass compositions that were obtained from the primary studies using glass beads. As a result of this study, specific composition of both zinc and strontium phosphate glass, having the most favourable cellular response, was recommended to be used for the following experiments. Based on previous compositions, another study was performed to surface functionalise glass discs by coating them with carbon nanotubes (CNTs) and polycaprolactone polymer (PCL) to assess the effect of surface modification on cellular adhesion and metabolic activity. This was subsequently followed by manufacturing, mechanical testing and structural evaluation of zinc and strontium scaffolds. Another experiment was carried out to identify the most suitable technique for scaffold cells seeding by coating scaffolds with fibronectin and collagen. The final study aimed to assess different types of zinc and strontium phosphate glass scaffolds (non-coated, CNT-coated) in both static and dynamic conditions. For the assessment of these scaffolds under dynamic conditions, a perfusion bioreactor was custom made that worked continuously for 28 days. The results revealed that the most preferable glass compositions were identified as ZnO5% and SrO17.5%. Also, glass coating with CNTs and PCL has found to encourage cells adhesion and metabolic activity as it enhanced both surface roughness and hydrophilicity. Scaffold production by sintering technique was thermally optimised and scaffold cellular seeding using collagen coating has yielded the most efficient seeding density. The final results displayed that the most suitable cellular response was found in CNT and PCL coated scaffolds under dynamic conditions (perfusion bioreactors cultivated scaffolds)

Enhancing the cooling system of a residential building using integrated building information modelling with solar absorption system

Building energy management is concerned with the energy consumption of the building. The used electricity in the residential building has the highest percentage when applying HVAC systems among all other building services installations and other electric appliances. For that, the present work focuses on the cooling load capacity issues and the methods to reduce the amount of electricity used in the building, particularly in air conditioning systems. In order to achieve this target, three main steps were applied; the first step was calculating the cooling load capacity by using the Cooling Load Temperature Difference method (CLTD) method. The second step was to find a sustainable wall material that could reduce the cooling load requirements using Building Information Model (BIM). The sustainable material was a new type of concrete block with a high insulation capability. The final step was to analyse the required energy of the cooling system device by using an applied Engineering Equation Solver (EES) to obtain accurate results. Two types of cooling systems were tested to determine the economic device based on the energy required to operate them under the same conditions. The two cooling systems were the conventional vapour-compression and solar absorption systems. The EES program evaluates the mathematical model and calculations for these systems to investigate the performance coefficient of the selected air-conditioning systems within (May, June, July and August) months in Iraq. This program evaluated the cooling systems by calculating the cost of used power. The results observed that the use of sustainable material reduces the building energy consumption by about 20%, and the solar absorption system is the best device for cooling systems. The solar absorption system provided the best COP in May, which was 0.8048

Advanced biocomposites of poly(glycerol sebacate) and β-tricalcium phosphate by in situ microwave synthesis for bioapplication

Biodegradable poly(glycerol sebacate) [PGS] has gained substantial attention in the soft tissue engineering field over the past few years, but its application is limited because its fast degradation rate causes an acidic environment which can adversely affect cell viability and eventually tissue growth. β-tricalcium phosphate (β-TCP) is an ideal biocompatible candidate to mitigate these drawbacks of PGS. This work for the first time rationalizes a biocomposite composed of PGS and β-TCP prepared by a fast and well-controlled microwave approach. As expected, the presence of β-TCP particles (i) improves the degree of cross-linking of PGS, thus decreasing the sol content by ca. 66%, (ii) enhances its hydrophilicity with much lower contact angle, (iii) reduces the degradation rate by a factor of two and (iv) increases the swelling effect of the biocomposite by ca. 10%. Furthermore both PGS/β-TCP150 and PGS/β-TCP180 biocomposites demonstrate significant difference in cell viability form the single PGS materials, which is more than 65% higher in cell growth in one day proliferation, demonstrating an advanced biomaterial embodying both advantages of PGS polymer and β-TCP bioceramics