http://repository.aust.edu.ng/xmlui/handle/123456789/278 These are publications by AUST PhD students (Ex-students). Thu, 16 Apr 2026 18:25:43 GMT 2026-04-16T18:25:43Z http://repository.aust.edu.ng/xmlui/handle/123456789/4885 A shear assay study of single normal/breast cancer cell deformation and detachment from poly-di-methyl-siloxane (PDMS) surfaces Ani, Chukwuemeka J.; Obayemi, John David; Ozonwanne, Vanesa; Danyuo, Yiporo This paper presents the results of a combined experimental and analytical/computational study of viscoelastic cell deformation and detachment from poly-di-methyl-siloxane (PDMS) surfaces. Fluid mechanics and fracture mechanics concepts are used to model the detachment of biological cells observed under shear assay conditions. The analytical and computational models are used to compute crack driving forces, which are then related to crack extension during the detachment of normal breast cells and breast cancer cells from PDMS surfaces that are relevant to biomedical implants. The interactions between cells and the extracellular matrix, or the extracellular matrix and the PDMS substrate, are then characterized using force microscopy measurements of the pull-off forces that are used to determine the adhesion energies. Finally, fluorescence microscopy staining of the cytosketelal structures (actin, micro-tubulin and cyto-keratin), transmembrane proteins (vimentin) and the ECM structures (Arginin Glycine Aspartate – RGD) is used to show that the detachment of cells during the shear assay experiments occurs via interfacial cracking between (between the ECM and the cell membranes) with a high incidence of crack bridging by transmembrane vinculin structures that undergo pull-out until they detach from the actin cytoskeletal structure. The implications of the results are discussed for the design of interfaces that are relevant to implantable biomedical devices and normal/cancer tissue. Mon, 12 Nov 2018 00:00:00 GMT http://repository.aust.edu.ng/xmlui/handle/123456789/4885 2018-11-12T00:00:00Z http://repository.aust.edu.ng/xmlui/handle/123456789/575 Extended pulsated drug release from PLGA-based minirods Danyuo, Yiporo The kinetics of degradation and sustained cancer drugs (paclitaxel (PT) and prodigiosin (PG)) release are presented for minirods (each with diameter of ~5 and ~6 mm thick). Drug release and degradation mechanisms were studied from solvent-casted cancer drug-based mini- rods under in vitro conditions in phosphate buffer solution (PBS) at a pH of 7.4. The immersed minirods were mechanically agitated at 60 revolutions per minute (rpm) under incubation at 37 °C throughout the period of the study. The kinetics of drug release was studied using ultraviolet visible spectrometry (UV-Vis). This was used to determine the amount of drug released at 535 nm for poly (lactic-co-glycolic acid) loaded with prodigiosin (PLGA- PG) samples, and at 210 nm, for paclitaxel-loaded samples (PLGA-PT). The degradation characteristics of PLGA-PG and PLGA-PT are elucidated using optical microscope as well as scanning electron microscope (SEM). Statistical analysis of drug release and degradation mechanisms of PLGA-based minirods were performed. The implications of the results are discussed for potential applications in implantable/degradable structures for multi-pulse cancer drug delivery. Tue, 07 Feb 2017 00:00:00 GMT http://repository.aust.edu.ng/xmlui/handle/123456789/575 2017-02-07T00:00:00Z http://repository.aust.edu.ng/xmlui/handle/123456789/282 Analysis of Solar Radiation Data in Northern Ghana Danyou, Yiporo; Ampaw, Edward; Musa, Abdulai Energy plays a significant role in life. Humans need energy to operate in industries, agriculture, transport and services. Due to increasing population and technological development, humans consume more energy than before, resulting in higher air pollution, damming of rivers, creation of nuclear waste, and other environmental drawbacks. Almost all energy used today is non-renewable which takes a long time to reproduce. Solar energy therefore originates from the nuclear reaction within the sun’s hot core (i.e. about 6×106K), and is transmitted to the sun’s surface by radiation and hydrogen convection (Roger et al., 2003). Solar energy is the radiant light and heat from the sun that has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar energy contributes 99.98% of all the energy that drives processes on Earth (Dorothy, 1998). Sun, 01 Jan 2012 00:00:00 GMT http://repository.aust.edu.ng/xmlui/handle/123456789/282 2012-01-01T00:00:00Z http://repository.aust.edu.ng/xmlui/handle/123456789/281 Design of Thermally Reliable Environmental Barrier Coating for a SiC/SiC Ceramic Matrix Composites Danyou, Yiporo; Arthur, Emmanuel Kwesi; Ampaw, Edward; Azeko, S.T.; Agyei-Tuffour, B.; Kan-Dapaah, Kwabena; Obayemi, John David Silicon carbide-fiber-reinforced silicon carbide matrix composites (SiC/SiC CMCs) have been proven to possess greater high-temperature strength and durability. These materials are usually used in air breathing engines due to their unique properties. However, the application of SiC/SiC CMCs is ineffective in combustion environment due to oxidation and surface recession. Efforts to improve service of SiC/SiC CMCs in combustion environments require knowledge of their long-term stability in combustion environments, volatility, phase stability, and thermal conductivity. Therefore in this paper, the design of a reliable EBC for SiC/SiC CMCs with excellent corrosion, recession and thermal shock resistance is proposed. This design consists of a three-multilayer; yttrium disilicate/mullite/ytterbium disilicate (Y2Si2O7/ 3Al2O3.2SiO2/Yb2Si2O7) system. Also, finite element models (FEMs) were used to predict the thermal residual stresses within the proposed multilayers under operating conditions. The implications of the results are discussed for potential application of this EBC system in air breathing engines. Tue, 01 Jan 2013 00:00:00 GMT http://repository.aust.edu.ng/xmlui/handle/123456789/281 2013-01-01T00:00:00Z