O'Donnell Sylvester | American University of Nigeria, Yola (original) (raw)

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Papers by O'Donnell Sylvester

The current study aims to determine the molecular mechanisms of age-related macular degeneration ... more The current study aims to determine the molecular mechanisms of age-related macular degeneration (AMD) using the phosphorylation network. Specifically, we examined novel biomarkers for oxidative stress by protein interaction mapping using in vitro and in vivo models that mimic the complex and progressive characteristics of AMD. We hypothesized that the early apoptotic reactions could be initiated by protein phosphorylation in region-dependent (peripheral retina vs. macular) and tissue-dependent (retinal pigment epithelium vs. retina) manner under chronic oxidative stress. The analysis of protein interactome and oxidative biomarkers showed the presence of tissue-and region-specific post-translational mechanisms that contribute to AMD progression and suggested new therapeutic targets that include ubiquitin, erythropoietin,

This paper summarizes the effect of inhibitors on the corrosion of stainless steels and aluminium... more This paper summarizes the effect of inhibitors on the corrosion of stainless steels and aluminium alloys in different media. Stainless steels and aluminium alloys have a wide range of applications in construction, transport, domestic appliances, medical, and energy related fields. The exposure of stainless steels and aluminium alloys to corroding environments however, results in the degradation of the materials. Inhibitors are used to mitigate the corrosion of these alloys in various corrosive media and enhance their durability. Corrosion inhibitors can either be anodic inhibitors, cathodic inhibitors, mixed inhibitors, or volatile corrosion inhibitors. This review showed that inhibition efficiency increases with increase in inhibitor concentration irrespective of alloy tested. However, adsorption of inhibitors on the alloys' surface depends on the alloy type. Adsorption of inhibitors on the surface of stainless steels obeyed Langmuir adsorption isotherms, while those of aluminium alloys obeyed Langmuir, Temkin, Flory-Huggins and Freundlich isotherms. This study is important for different industrial fields where stainless steels and aluminium alloys are utilized.

Biodiesel is produced from vegetable oils and animal fats by transesterification reaction in the ... more Biodiesel is produced from vegetable oils and animal fats by transesterification reaction in the presence of an acidic, alkaline or enzymatic catalyst. The application of biodiesel as an alternative to fossil fuels is growing; however, the optimization of reaction parameters to obtain maximum yield is still an area of research that can be further explored. The current methods of biodiesel production employ the use of acidic, basic, solid and enzymatic catalysts to obtain high yields and lower the cost of production. In this paper, various catalysts that have been explored over the past decade are reviewed to obtain an understanding of the progress made in the field of biodiesel catalysis. Areas of potential interest like the exploration of catalysts from natural sources are also explored and recommended for further studies.

Previously, our molecular binding study showed that prohibitin interacts with phospholipids, incl... more Previously, our molecular binding study showed that prohibitin interacts with phospholipids, including phosphatidylinositide and cardiolipin. Under stress conditions, prohibitin interacts with cardiolipin as a retrograde response to activate mitochondrial proliferation. The lipid-binding switch mechanism of prohibitin with phosphatidylinositol-3,4,5-triphosphate and cardiolipin may suggest the role of prohibitin effects on energy metabolism and age-related diseases. The current study examined the region-specific expressions of prohibitin with respect to the retina and retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). A detailed understanding of prohibitin binding with lipids, nucleotides, and proteins shown in the current study may suggest how molecular interactions control apoptosis and how we can intervene against the apoptotic pathway in AMD. Our data imply that decreased prohibitin in the peripheral RPE is a significant step leading to mitochondrial dysfunction that may promote AMD progression.

The rates of corrosion of zinc and copper materials at room temperature, 40°C and 60°C in biodies... more The rates of corrosion of zinc and copper materials at room temperature, 40°C and 60°C in biodiesels obtained from olive, groundnut and soya oils were studied. The study showed that copper materials have a higher corrosion rate in the biodiesels studied compared to zinc materials. The corrosion rate of zinc materials increased with increase in temperature of the biodiesels over a period of time.

The current study highlights biodiesel and ethanol production from Balanite aegyptiaca and Azadir... more The current study highlights biodiesel and ethanol production from Balanite aegyptiaca and Azadirachta indica plants. Both plants are capable of producing the parent oil as long-chain fatty acid triglycerides showing thirty per cent yield, followed by biodiesel synthesis with high yield. Balanite aegyptiaca showed a higher biodiesel yield (75%) compared to Azadirachta indica (49%). In addition, Balanite aegyptiaca is lighter, showing specific gravity of 0.83 and lower viscosity (4.98 mm2/s) relative to that of Azadirachta indica seed, which has viscosity and specific gravity values of 5.25 mm2/s and 0.85, respectively. The biomass from the seeds is further used to generate bioethanol to optimize the utility of the seeds in biofuel production to maximize carbon recycling.

The current study tested the hypothesis as to whether or not polyethylene-based plastic can be co... more The current study tested the hypothesis as to whether or not polyethylene-based plastic can be converted to liquid fuel by
thermal catalytic cracking over metal oxide catalysts, including Ca(OH)2, Al2O3, and ZnO. To determine the optimum condition for the highest yield of low molecular weight (C5-C22, MW=100-300) liquid fuel production, the catalyst-to-polymer ratio was investigated at various temperature and reaction times. The initial liquid product obtained from each catalyst was further cracked to yield hydrocarbons of lower molecular mass. The obtained final products were analyzed by gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography (HPLC), infrared resonance (FT-IR), and elemental analysis (EA). The GC/MS analysis demonstrated that the fuel obtained had constituents ranging from carbon numbers of 5-22. The FT-IR spectra showed the expected functional group and the element analyzer indicated the gross and net heating values of the fuel to be within the range 61-383 MJ/Kg. Comparative analysis showed that Ca(OH)2 has the highest total conversion yield followed by Al2O3 and then ZnO.

Biodiesel is a substitute diesel fuel produced from vegetable oils or animal fats by trans-esteri... more Biodiesel is a substitute diesel fuel produced from vegetable oils or animal fats by trans-esterification in the presence of a catalyst. Due to its environmental friendliness, its use is becoming necessary in all regions, however, there are problems associated with its fluidity in cold temperatures. This paper examines the cold flow properties as well as the kinematic viscosity of produced biodiesels. The review shows that both properties are affected by the length of the carbon chain and degree of saturation. However, these can be improved by blending either with petro-diesel or less saturated FAME, as well as the use of some additives.

The concerns on climate change, the high energy prices and the dwindling oil reserves and supplie... more The concerns on climate change, the high energy prices and the dwindling oil reserves and supplies have necessitated a strong interest in the research for alternative fuel sources. Biodiesel is an alternative renewable fuel that has gained massive attention in recent years.Studies on the physical properties of biodiesel have shown that it is completely miscible with petroleum diesel. Since the combustion of biodiesel emits particulate matter and gases which is lower than petrodiesel, combustion of biodiesel and biodiesel blends have shown a significant reduction in particulate matter and exhaust emissions.In this review paper, the use of pure biodiesel or biodiesel blends in terms of performance and exhaust emissions has been studied in comparison to petroleum diesel.

The study of the interaction between matter and radiation is known as spectroscopy and it is seen... more The study of the interaction between matter and radiation is known as spectroscopy and it is seen as a suitable and precise analytical method in quality control analysis. Spectroscopy is vital in analysis of biodieselgiven that biodiesel has gained considerable attention in recent years due to its merits: biodegradable, renewable, non-toxic, less emission of gaseous and particulate pollutants with higher cetane number than normal fossil fuels. Spectroscopic methods could be atomic or molecular though modern techniques of acoustic, mass and electron spectroscopy do not involve the electromagnetic radiation. In this review, we studied various spectroscopic methods that have been used to evaluate the quality of biodiesel as well as observe the process of transesterification. Infrared, Nuclear magnetic resonance, Ultraviolet-Visible, Thermal lens and Mass spectroscopies are important analytical tools reviewed in this paper.

Chromatographic analysis have been used in many ways in quantifying and identifying individual co... more Chromatographic analysis have been used in many ways in quantifying and identifying individual components in biodiesel samples, such as the identification of contaminants and Fatty acids methyl esters. Chromatography is vital in modern quality control analysis of biodiesel hence, its wide application in the study of biodiesel composition. These relevant studies have contributed immensely to the rapid growth of biodiesel production and analysis, with modern techniques providing better results. In this paper, several past research work on chromatographic analysis of Biodiesel from different oils have been reviewed.

Conference Presentations by O'Donnell Sylvester

Purpose: Age-related macular degeneration (AMD) involves progressive cell death of postmitotic RP... more Purpose: Age-related macular degeneration (AMD) involves progressive cell death of postmitotic RPE cells. The current study examines the correlation between prohibitin as a metabolic anti-apoptotic switch with phospholipids in a stress-dependent manner. The changes of prohibitin-lipid interaction in RPE identify key elements of apoptotic networks that follow lipid metabolism and serve as a framework of biochemical pathways in AMD.

The current study explores epigenetic control of gene expression and oxidative responses through ... more The current study explores epigenetic control of gene expression and oxidative responses through modulating phosphoproteome in the retina and RPE cells. We examined a novel role of phosphorylation signaling as an adaptation to extracellular stress and used phosphoproteome alterations to determine early molecular mechanism of retina/RPE cell death and survival. Our hypothesis is that decreased transferrin and increased kinase/phosphatase activity in AMD could be responsible for regulated apoptotic phosphorylation signaling during AMD progression.