Network modelling studies of depressurisation and repressurisation processes in porous media

This thesis presents an analysis of gas evolution and re-dissolution behaviour associated with the depressurisation and repressurisation of hydrocarbon-saturated porous media. A network modelling approach is adopted, whereby the porous medium is represented by an interconnected lattice of well-characterised pore elements of varying sizes. A modified invasion percolation approach is implemented for modelling the advance of gas/liquid interfaces under the combined effects of capillary, gravitational, and viscous forces. A wide range of experimentally observed pore level mechanisms and measured PVT parameters are included in the model, including: bubble nucleation, diffusive mass transport, expansion, bubble fragmentation and coalescence, oil shrinkage, unsteady-state gas migration, and oil re-imbibition. Network simulations are validated against experimental results, with comparisons providing comprehensive explanations for several poorly understood observations. Under depressurisation, transitions from non-dispersive to dispersive gas flow are found to be influenced by a number of pore-scale petrophysical parameters including; mean capillary entry radius, network connectivity, interfacial tension and pore-size distribution variance. Results show that gas flow regime and experimental protocol crucially affect the definition of critical gas saturation and the value of final gas saturation (an indicator of oil recovery) during pressure depletion. Repressurisation simulations are also presented and these clearly show how hysteresis in gas saturation between depletion and repressurisation is a manifestation of hysteresis in more fundamental properties including, supersaturation, interfacial area, the total number of gas clusters, and the total mass in the gas phase. Furthermore, secondary depletion following repressurisation can lead to a significant increase in recovery when compared with that resulting from primary depletion.Total E&P UK Lt

Evaluation of functionalized silver and silica nanoparticles for the removal of deoxyribonucleic acid conveying antibiotics resistance genes from water

Antibiotic resistance genes ARGs are recognized as a serious public health emergency linked to extensive use of antibiotics by humans and animals as a prophylactic agent that treats and prevents infections. The occurrence of high concentrations being identified in wastewater treatment plants, rivers, etc is due to untreated effluents being discharged from households, hospitals, agriculture, and pharmaceutical industries. The application of adequate treatment techniques and material for the removal of bacteria DNA conveying ARGs from the effluents before their release to the environment cannot be overemphasized. Adsorption techniques seem to be effective due to their easy design, operation, and ability to regenerate adsorbents for use without producing toxic by-products. This concept was employed for the removal of bacteria DNA conveying ARGs from simulated aqueous solution, effluents from hospital, river and WWTPs using silver and silica metallic nanoparticles. This thesis investigated the effectiveness of metallic nanoparticles containing silver AgNPs and mesoporous silica nanoparticles MSNPs as well as magnetite Fe3O4 functionalized with 4 4hydroxyphenyl 2 262-terpyridine onto their surface, for the removal of bacteria DNA conveying antibiotic resistance genes from water samples from hospitals, river, and wastewater treatment plants WWTPs. Silver nanoparticles AgNPs of different molar concentrations 0.1M, 0.5M and 1.0 M and mesoporous silica nanoparticles MSNPs adsorbents were successfully synthesized in their original states and surface functionalization achieved by incorporating magnetite Fe3O4 and 4 4 hydroxyphenyl 2 2 6 2 terpyridine on the silver AgNPs Fe3O4 and silica MSNPs TPPY surfaces respectively. Their effectiveness as adsorbent for the removal of bacteria DNA conveying ARGs from aqueous solutions and real water/wastewater samples were investigated. The DNA uptake by the as-synthesized AgNPs and MSNPs were compared to the functionalized AgNPs Fe3O4 and MSNPsTPPY by determining the adsorbents with the highest removal efficiencies. All as synthesized and functionalized adsorbents were characterized by SEM, EDX, FTIR, XRD, UV spectroscopy and PZC before the removal process. The extraction of genomic DNA from antibiotic-resistant Enterococcus faecium and Vibrio parahaemolyticus was successfully achieved via the boiling method. Antibiotic susceptibility test was conducted using the disk diffusion method before the commencement of genomic DNA extraction. Molecular characterization via gel electrophoresis confirmed the presence of resistance genes at different base pairs. Adsorption batch experiment were investigated, and the best optimum parameters were evaluated through the influence of pH, contact time, initial DNA concentration, adsorbent dose, and competitive ions for each sorption process. The rate determining step were determined by fitting kinetic models such as Natarajan and Khalaf first order, pseudo first order, pseudo second order, Elovich model to experimental data. Also, the adsorption mechanisms determining adsorption equilibrium were investigated by fitting Freundlich, Langmuir and Sips model into the experimental data. The application of AgNPsFe3O4 nanocomposite and MSNPsTPPY for the removal of bacteria DNA demonstrated much enhancement for DNA uptake than the as-synthesized AgNPs and MSNPs materials. The incorporation of magnetite and 4 4hydroxyphenyl 2 2 6 2-terpyridine onto AgNPs and MSNPs significantly enhanced the binding affinity towards the removal the bacteria DNA via strong electrostatic attraction between the active sites on the adsorbent and the negative DNA molecules. Finally, high adsorption capacities were recorded with AgNPsFe3O4 nanocomposite and MSNPsTPPY compared to AgNPs and MSNPs with chaotropic salts. The kinetic adsorption models were mostly best fitted by the pseudo-second order and Elovich models while the adsorption equilibrium was best described by Langmuir and Sips isotherm models. MSNPs with different chaotropic salts, AgNPsFe3O4 nanocomposite and MSNPsTPPY also proved its effectiveness in DNA removal not only in the simulated aqueous solution but in three different real life water samples obtained from Cofimvaba hospital, Ndevana river and Uitenhage WWTPs. High adsorption efficiencies above 90 percent were achieved during the removal of DNA in all the three real water samples. Therefore, application of these adsorbents for the removal of bacteria DNA conveying ARGs may be a promising option that would tackle the consequences of consuming ARGs infected water globally.Thesis (MSc) -- Faculty of Science and Agriculture, 202

Evaluation of functionalized silver and silica nanoparticles for the removal of deoxyribonucleic acid conveying antibiotics resistance genes from water

Antibiotic resistance genes ARGs are recognized as a serious public health emergency linked to extensive use of antibiotics by humans and animals as a prophylactic agent that treats and prevents infections. The occurrence of high concentrations being identified in wastewater treatment plants, rivers, etc is due to untreated effluents being discharged from households, hospitals, agriculture, and pharmaceutical industries. The application of adequate treatment techniques and material for the removal of bacteria DNA conveying ARGs from the effluents before their release to the environment cannot be overemphasized. Adsorption techniques seem to be effective due to their easy design, operation, and ability to regenerate adsorbents for use without producing toxic by-products. This concept was employed for the removal of bacteria DNA conveying ARGs from simulated aqueous solution, effluents from hospital, river and WWTPs using silver and silica metallic nanoparticles. This thesis investigated the effectiveness of metallic nanoparticles containing silver AgNPs and mesoporous silica nanoparticles MSNPs as well as magnetite Fe3O4 functionalized with 4 4hydroxyphenyl 2 262-terpyridine onto their surface, for the removal of bacteria DNA conveying antibiotic resistance genes from water samples from hospitals, river, and wastewater treatment plants WWTPs. Silver nanoparticles AgNPs of different molar concentrations 0.1M, 0.5M and 1.0 M and mesoporous silica nanoparticles MSNPs adsorbents were successfully synthesized in their original states and surface functionalization achieved by incorporating magnetite Fe3O4 and 4 4 hydroxyphenyl 2 2 6 2 terpyridine on the silver AgNPs Fe3O4 and silica MSNPs TPPY surfaces respectively. Their effectiveness as adsorbent for the removal of bacteria DNA conveying ARGs from aqueous solutions and real water/wastewater samples were investigated. The DNA uptake by the as-synthesized AgNPs and MSNPs were compared to the functionalized AgNPs Fe3O4 and MSNPsTPPY by determining the adsorbents with the highest removal efficiencies. All as synthesized and functionalized adsorbents were characterized by SEM, EDX, FTIR, XRD, UV spectroscopy and PZC before the removal process. The extraction of genomic DNA from antibiotic-resistant Enterococcus faecium and Vibrio parahaemolyticus was successfully achieved via the boiling method. Antibiotic susceptibility test was conducted using the disk diffusion method before the commencement of genomic DNA extraction. Molecular characterization via gel electrophoresis confirmed the presence of resistance genes at different base pairs. Adsorption batch experiment were investigated, and the best optimum parameters were evaluated through the influence of pH, contact time, initial DNA concentration, adsorbent dose, and competitive ions for each sorption process. The rate determining step were determined by fitting kinetic models such as Natarajan and Khalaf first order, pseudo first order, pseudo second order, Elovich model to experimental data. Also, the adsorption mechanisms determining adsorption equilibrium were investigated by fitting Freundlich, Langmuir and Sips model into the experimental data. The application of AgNPsFe3O4 nanocomposite and MSNPsTPPY for the removal of bacteria DNA demonstrated much enhancement for DNA uptake than the as-synthesized AgNPs and MSNPs materials. The incorporation of magnetite and 4 4hydroxyphenyl 2 2 6 2-terpyridine onto AgNPs and MSNPs significantly enhanced the binding affinity towards the removal the bacteria DNA via strong electrostatic attraction between the active sites on the adsorbent and the negative DNA molecules. Finally, high adsorption capacities were recorded with AgNPsFe3O4 nanocomposite and MSNPsTPPY compared to AgNPs and MSNPs with chaotropic salts. The kinetic adsorption models were mostly best fitted by the pseudo-second order and Elovich models while the adsorption equilibrium was best described by Langmuir and Sips isotherm models. MSNPs with different chaotropic salts, AgNPsFe3O4 nanocomposite and MSNPsTPPY also proved its effectiveness in DNA removal not only in the simulated aqueous solution but in three different real life water samples obtained from Cofimvaba hospital, Ndevana river and Uitenhage WWTPs. High adsorption efficiencies above 90 percent were achieved during the removal of DNA in all the three real water samples. Therefore, application of these adsorbents for the removal of bacteria DNA conveying ARGs may be a promising option that would tackle the consequences of consuming ARGs infected water globally.Thesis (MSc) -- Faculty of Science and Agriculture, 202

Stem Bark Extracts of Ficus exasperata protects the Liver against Paracetamol induced toxicity in Wistar Rats

Ficus exasperata is an important medicinal plant with a wide geographicaldistribution in Africa particularly in Nigeria. In this study, aqueous stem bark extracts of Ficus exasperata were administered to investigate its hepatoprotective effects on Paracetamol induced liver toxicity in Wistar rats. A total of Twenty Five Wistar rats were randomly divided into fivegroups labeled A-E and kept in a well ventilated room. Group A served as control and were treated with distilled water. Rats in groups B-E were all treated with Paracetamol (800mg/kg body weight) but rats in group C, D and E were however pretreated with Silymarin (50 mg/kg bw), 100mg/kg bw aqueous stem bark extracts of Ficus exasperata and 200mg/kg bw aqueous stem bark extracts of Ficus exasperata respectively one hour before Paracetamol administration for fourteen days. Animals were sacrificed twenty four hours after the last treatment. Blood samples were collected into heparinized bottles for biochemical estimation of liver enzymes and the liver was harvested for routine histological examination. Paracetamol produced significant changes in biochemical parameters (increases in serum Alanine Aminotransferase (ALT), Aspartate  Aminotransferase (AST), Alkaline Phosphatase (ALP), with a reduction in Total protein) and Liver histology (damage to hepatocytes). Pretreatment with Silymarin and aqueous stem bark extracts of Ficus exasperata  significantly prevented the biochemical and histological changes induced by Paracetamol in the liver. In conclusion, our histological and biochemical findings indicate that aqueous stem bark extracts of Ficus exasperata possesses hepatoprotective properties. © JASE

Extraction, Physicochemical, Phytochemical Analysis And Identification Of Some Important Compounds Of Monodora Myristica (African Nutmeg) Seed Oil

The oil from African nutmeg seed (Monodora myristica) also known as ehuru in Igbo or Ariwo in Yoruba was extracted using normal hexane. Physico-chemical analysis, phytochemical analysis and GC-MS was carried out from crude extract. Physico-chemical analysis indicated that Iodine value (4.318 mg), Peroxide value (10.1 meq/ kg), Acid value (0.784 mg KOH /g), Saponification value (246.1 mg KOH g-), Refractive index (1.479), Specific gravity (0.968 g/m L) and % yield (36.04%). GC-MS analysis shed n-Hexadecanoic acid, Arachidonic acid, 9- Octadecanoic acid to be a major component of the seed oil. The results suggest that the oil is non drying oil; free from rancidity therefore it is good for cooking

Assessment of Dermatoglyphic Patterns and Sex Distribution in Esan Ethnic Group of Edo State, Nigeria

This study was carried out to find out the possibility of a unique pattern of palm and finger prints (Dermatoglyphics) among 192 adults (96 males and 96 females) of Esan origin who, at the time of this study, were residing in Esan-land - the central senatorial district of Edo state, Nigeria. The subjects were selected via multi-stage sampling technique and fingerprint determination was performed using the Indian ink methods. Palm and fingerprints were observed for the angles connecting the triradii at the roots of the fingers (a-index finger, b-middle finger, c-ring finger d-small finger and t-the most proximal triradii in the palm) taken as atd, tad and tda angles. The data collected were statistically analyzed using the Statistical Package for Social Science (SPSS) using the student t-test, chi square test and ANOVA as statistical tools. Results showed that the loop pattern had the highest frequency (61.7%) followed by whorl (24.9%), arch (12.8%) and double whorl (0.6%). The mean atd angles were 43.49 for males and 44.02 for females; tad angles were 75.11 for males and 74.71 % for females; and tda were 61.22% for males and 61.35% females. These reveals that the pattern of finger prints distribution were similar for both sexes except that the males had more arches on the right hand (53%) than the females with more arches on the left hand (57.1%).Keywords: Esan people, Dematoglyphic Patterns, Finger Prints, Pal

Stem Bark Extracts of Ficus exasperata protects the Liver against Paracetamol induced toxicity in Wistar Rats

Ficus exasperata is an important medicinal plant with a wide geographical distribution in Africa particularly in Nigeria. In this study, aqueous stem bark extracts of Ficus exasperata were administered to investigate its hepatoprotective effects on Paracetamol induced liver toxicity in Wistar rats. A total of Twenty Five Wistar rats were randomly divided into five groups labeled A-E and kept in a well ventilated room. Group A served as control and were treated with distilled water. Rats in groups B-E were all treated with Paracetamol (800mg/kg body weight) but rats in group C, D and E were however pretreated with Silymarin (50 mg/kg bw), 100mg/kg bw aqueous stem bark extracts of Ficus exasperata and 200mg/kg bw aqueous stem bark extracts of Ficus exasperata respectively one hour before Paracetamol administration for fourteen days. Animals were sacrificed twenty four hours after the last treatment. Blood samples were collected into heparinized bottles for biochemical estimation of liver enzymes and the liver was harvested for routine histological examination. Paracetamol produced significant changes in biochemical parameters (increases in serum Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Alkaline Phosphatase (ALP), with a reduction in Total protein) and Liver histology (damage to hepatocytes). Pretreatment with Silymarin and aqueous stem bark extracts of Ficus exasperata significantly prevented the biochemical and histological changes induced by Paracetamol in the liver. In conclusion, our histological and biochemical findings indicate that aqueous stem bark extracts of Ficus exasperata possesses hepatoprotective properties

Ineffective Communication in Nigeria: A Problem Associated with Low Level of Literacy

Communication is one thing. Effective communication is another. Specifically, for one to express an idea in speech or writing is one thing and expressing it as it is in one’s mind is another thing. Furthermore, receiving the idea through listening or reading is one thing while understanding it, as it is intended, to be able to make an adequate and appropriate response is another thing. This paper, by a simple study instrument, argues that the political, religious, economic, medical and educational problems in the country are a function of ineffective communication. It however makes recommendations for how to reduce it