No description available.

No description available.

In this work, I investigated the influence of different surfaces on stem cell proliferation and osteogenetic differentiation. Surface properties of biomaterials are important factors that influence cell fate such as cell adhesion, viability, proliferation and differentiation. Herein, mesenchymal stem cells (MSCs) were cultured on composite electrospun nanofibrous membranes with varied surface wettability for designed periods and cell morphologies, proliferation and viability were characterized via analysis methods such as Infrared attenuated total reflectance Spectroscopy (IR-ATR), scanning electron microscopy (SEM) and MTT cell proliferation assay. The expression of genes associated with osteogenesis, including bone sialoprotein (BSP), alkaline phosphatase (ALP), osteopontin (OPN) and osteocalcin (OCN) were measured by real-time RT-PCR on different time points. Through western blot analysis, ERK1/2 pathway was found to be responsible for the differentiation of MSCs on nanofibrous membranes with different wettability.

The Major Intrinsic Proteins are represented in all forms of life; plants, animals, bacteria and recently archaebacteria have all been shown to express at least one member of this superfamily of integral membrane proteins. We have overexpressed the E. coli aquaglyceroporin, glycerol facilitator (GlpF), to use as a model for studying membrane protein structure, folding and stability. Understanding membrane protein folding, stability, and dynamics is required for a molecular explanation of membrane protein function and for the development of interventions for the hundreds of membrane protein folding diseases. X-ray analysis of GlpF crystals shows that the protein exits as a tetramer in the crystallized state [1]. However, preparations of stable aqueous detergent solutions of GlpF in its native oligomeric state have been difficult to make; the protein readily unfolds and forms non-specific aggregates in many detergents. Here, I report the study of the structure and stability of the glycerol facilitator in several detergent solutions by blue native and sodium dodecyl sulphate polyacrylamide gel electrophoresis, circular dichroism, and fluorescence. For the first time, stable protein tetramers were prepared in two different detergent solutions (dodecyl maltoside (DDM) and lyso-myristoyl phosphatidylcholine (LMPC)) at neutral pH. Thermal unfolding experiments show that the protein is slightly more stable in LMPC than in DDM and that the thermal stability of the helical core at 95oC is slightly greater in the former detergent. In addition, tertiary structure unfolds before quaternary and secondary structures in LMPC whereas unfolding is more cooperative in DDM. The high stability of the protein is also evident from the unfolding half-life of 8 days in 8 M urea suggesting that hydrophobic interactions contribute to the stability. The GlpF tetramers are less resistant to acidic conditions; LMPC-solubilized GlpF shows loss of tertiary and quaternary structure by pH 6, while in DDM the tertiary structure is lost by pH 5, however the tetramer remains mostly intact at pH 4. The implications of thermal and chemical stress on the stability of the detergent-solubilized protein and its in vivo folding are discussed.

Many tumour cells are more sensitive to hyperthermia than non-cancerous cells. The nature of this greater thermal sensitivity is not clear. The present study indicates that a likely cause for this increased thermal sensitivity is membrane-associated. Plasma membrane enriched fractions were obtained from two solid rat tumours: D23, a hepatoma, and Mc7, a sarcoma. Lipids from these membranes were extracted, characterized, and compared to equivalent fractions from control tissue (liver). In both cases the tumour membranes had lowered cholesterol: phospholipid ratios. There was little differenceln the phospholipid classes, but there was somecliSigfetice in the fatty acid composition of the individual phospholipids. Fluorescence polarization studies were carried out on whole membranes and indicated that the overall 'order' of the tumour membranes was decreased with respect to the controls. In addition a plasma membrane bound enzyme, the Mg2+ATPase, was found to be considerably more thermolabile in the tumour cells. The addition of the membrane pertubant tetracaine produced a greater degree of disorder in the tumour membranes compared to controls, and enhanced the thermolability of the Mg2+ATPase. These differences are further evidence that the plasma membrane is a likely site for the primary lesion in cell heat injury. Results from in vivo studies support the above mentioned in vitro work. D23 and Mc7 tumours, grown in the foot, were subject to hyperthermia and the simultaneous application of a membrane perturbant, tetracaine. The addition of the tetracaine significantly increased the efficacy of the treatment. When the D23 tumour was grown in ethanol-dependent rats there was no difference in the 'adaptive' response of the tumour, compared to the normal, plasma membranes. There was no difference in the heat sensitivity of foot tumours grown in ethanol-fed rats compared to tumours from pair fed controls.

Environmental awareness has increased significantly during the past years and the need to replace fossil fuels with a more sustainable alternative has become a priority in the modern society. Algal biofuels have shown to have a good productivity compared to other biomass feedstock options but the high cost- low-efficiency cultivation process has proven to be a challenge. The purpose of this project is to use membrane technologies to recover algal biomass more efficiently. This technology would significantly reduce the water usage and energy input to the algal biomass production process. In this study, the Derjaguin-Landau-Verwey-Overbeek (DLVO) model derived using the Surface Element Integration (SEI) technique was used to identify the interaction energy between 3 microalgae species and 5 hollow fiber membrane materials. The results suggested that Scendesmus Obliquous would have the lowest energy barrier (-2.7834 kT) with a Poly(vinylbutyral) (PVB) hollow fiber membrane, therefore it would have a greater initial number of algal cells attaching to the membrane, compared to the other microalgae and membrane materials studied. Further work needs to be completed in order to integrate algae growth and biomass harvesting into the actual model.

Basal reinforcement along with individually capped foundation piles is used in cases where both embankment stability and surface settlement control are required. The technique has been utilised to prevent differential settlement between new embankment construction over soft soil and an existing embankment where settlement has ceased. The piled embankment solution is also adopted to prevent differential settlement between an approach embankment constructed over soft soil and the piled foundations of a bridge abutment. The study was conducted to investigate the behaviour of an idealised piled embankment incorporating basal geosynthetic reinforcement. Three-dimensional model tests at self-weight conditions were carried out to evaluate the effect of some of the factors affecting the arching mechanism and the development of surface settlement in piled embankments. The physical model was designed to represent a square grid of individually capped piles centrally located within an embankment. Three different pile cap sizes and four different geosynthetic materials were employed in the experimental study. A movable base supported on hydraulically operated jacks was used to model the soft ground. The use of a movable base permitted the simulation of a worst case scenario in which the soft ground was not involved in the load sharing mechanism. The experimental results indicated the existence of two modes of behaviour pertaining to a shallow and deep mechanism. The piled embankment geometry represented by a combination of height of fill, pile cap size and spacing was found to govern the mode of behaviour. The arching mechanism in the fill was found to be mobilised at a relatively small reinforcement deflection which supported the adoption of the two step approach utilised in designing the basal reinforcement. The circular and parabolic arc geometries were found to be adequate in describing the deflected shape of the reinforcement. The use a modified flexible cable formulation to describe the loaddeflection response of the reinforcement was found to be in good agreement with the experimental results. In addition, the validity of a number of current methods and recommendations relating to the design of piled embankments was addressed. A numerical study was undertaken using FLAC, a plane strain finite difference based programme. The calculated and measured results were compared to assess the suitability of modelling piled embankment behaviour using the finite difference programme. A parametric study was conducted to investigate the role of the basal reinforcement in the load transfer mechanism and in the prevention of surface settlement. The embankment geometry was identified as the significant factor influencing the reduction in differential settlement. A surface settlement mechanism was established based on results of the parametric study.

No description available.

No description available.

No description available.