Evaluation of the effects of aqueous extract of Parkinsonia aculeata leaves on kidney and liver function indices in albino rats

The present study was designed to evaluate the reno- and hepatotoxicity effects of aqueous extract of Parkinsonia Aculeate leaves in wistar albino rats. Twenty rats were randomly divided into five groups of four animals each. Group 1 served as control, receiving only water and food, while groups 2, 3, 4 and 5 were administered graded doses of the extract at 0.60, 1.20, 1.80 and 2.40 g/kg body weight respectively, orally, once daily for 28 days. There were no mortality or behavioural changes in the acute toxicity study at single dose of 3.00 g/kg bw for the period of 48 hours. The extract also showed no significant effect on changes in the body weights of the animals. Alanine Transaminase (ALT) activity was significantly (p<0.05) decreased at the dose of 2.40 g/kgbw of the extract. Aspartate Transaminase (AST) and Alkaline Phosphatase (ALP) activities were significantly (p<0.05) decreased at the doses of 1.80 and 2.40 g/kgbw. The serum total protein and albumin concentrations were significantly (p<0.05) increased at the dose of 2.40 g/kg bw of the extract. Serum creatinine, urea and uric acid levels were significantly (p<0.05) increased at the doses of 1.80 and 2.40g/kgbw. These results suggest that the aqueous extract of P. Aculeate leaves may be safe to the liver but toxic to the kidney and the toxicity is dose-dependent.Keywords: Toxicity, kidney, liver, extract, Parkinsonia aculeat

Foreign exploitation of tourism in Zakes Mda’s The Heart of Redness and The Whale Caller

The main land of Africa enriches a large amount of natural resources that has been extracted and exploited for years. However, many African countries still rank among the poorest nations on the globe. The exploitation and sale of natural resources to western corporations have not helped Africans escape poverty. In addition, there are social issues that evolved over time from the sale and exploitation of resources. This work presented various forms of contemporary tourism and discusses matters of sustainable tourism development for local communities in Zakes Mda’s fictional account of the Xhosa community in Qolorha-by-Sea. This work therefore addressed issues that are neglected in the postapartheid era through the characters used in the novels

Ancestral belief in Adebowale’s The Virgin and Ngugi’s The River Between

The focus in this work is the re-examination of the place of the ancestors in contemporary world. This paper critically evaluates the pre-colonial status of the ancestors and clearly explains the pride of place they once enjoyed. The invasions of religions, especially Christianity and Islam maliciously challenge the place of the ancestors today. It is the thrust of this paper that since the missionary religions have made a lot of converts among the traditional people, as a consequence, little or no regard is paid to them. The converts prefer to go their new worship centres instead of venerating their departed. The civilization the West brought to Africa had helped in no small way to pave way for the high disregards for them. This paper concludes that since the living ones do not even show moral sanctity Africa was once known for, propelled by greed and materialism, moral sanctity should be allowed to rest in peace

Tradition and modernity in Adebowale’s The Virgin and Out of His Mind

Before the advent of the Europeans, African had a balanced society where every endeavour was guided by societal values and norms. This work negates the principle that city life is better than village life and also highlight on morality as opposing lyrics perceived in tradition and modernity. The adverse effects of European incursion into Africa had brought permissiveness into African society to an extent that things have fallen apart and the centre of our cherished values and norms can no longer hold. The conflict between tradition and modernity (conflicts with culture, attitudes, behaviour, values, tastes) displayed by the major characters from the canvas on which the author weaves his vision

Techniques for Ensuring Fault Ride-Through Capability of Grid Connected DFIG-Based Wind Turbine Systems: A Review

Renewable energy sources (RES) are being integrated to electrical grid to complement the conventional sources to meet up with global electrical energy demand. Among other RES, Wind Energy Conversion Systems (WECS) with Doubly Fed Induction Generator (DFIG) have gained global electricity market competitiveness because of the flexible regulation of active and reactive power, higher power quality, variable speed operation, four quadrant converter operation and better dynamic performance. Grid connected DFIG-based WECS are prone to disturbances in the network because of direct connection of stator windings to grid. The ability of the Wind Turbine (WT) to remain connected during grid faults is termed the Fault Ride-Through (FRT) capability. The grid code requirement for integrating the DFIG-based WTs to power networks specified that they must remain connected and support the grid stability during grid disturbances of up to 1500 ms. The use of compensation devices offers the best FRT compliance thereby protecting the DFIG and the converters from voltage fluctuations and over currents during the grid fault. The paper presents a review of techniques employed in ensuring FRT compliance. The article also proposes the state-of-the-art techniques for compensating voltage sag/swell and limiting the fault short-circuit current. Keywords: Renewable energy sources, DFIG, wind turbine system, fault ride-through, grid codes, dual-functional DV

Geometry optimization and vibrational frequencies of tetracene molecule in gas phase and in methanol based on Density Funtional Theory and Restricted Hartree-Fock

Tetracene is an organic semiconductor with chemical formula C18H12 used in organic field effecttransistor (OFET) and organic light emitting diode (OLED). In this work, the molecular geometry (optimized bond lengths and bond angles), vibrational frequencies and intensities, HOMO-LUMO Energy gap and Atomic charge distribution of the Tetracene molecule in gas phase and in solution were calculated and reported. Restricted Hartree-Fock (RHF) and Density Functional Theory (DFT) with different basis sets were employed for the task. Windows version of Gaussian 03 software was used to perform all the calculations. The results obtained show that the bond length obtained using RHF has the lowest average value of 1.072Å and that obtained using DFT has the lowest average value of 1.085Å in gas phase. In Methanol, it is observed that at RHF level, the lowest average value was 1.075Å and at DFT level was 1.087Å. This shows that the values are a bit higher in methanol than in gas phase which implies that the bonds will be slightly stronger in gas phase than in methanol. The strongest bonds in tetracene molecule are those of C20-H28, C23-H29 and C24- H30 in both gas and methanol. The weakest bonds are those of C6-C12 and C6-C14.The bond angles were found to be so closed to 1200 at both levels of theory for all basis sets used suggesting that the molecule is planar benzene in which the C atoms are sp2 hybridized. The calculated HOMOLUMO energy gap shows that the molecule will be slightly more stable in chemical reaction in gas phase than in methanol. DFT values of the energy gap appeared to be closer to the reported experimental value of 2.6eV than those obtained by RHF. The atomic charges distribution was found to be very sensitive to the basis sets which presumably occur due to polarization. From the results obtained for vibrational frequencies, it shows that tetracene molecule would be more stable in gas phase that in methanol as a result of no imaginary frequency found in gas phase. This confirms the stability of the molecule as stated in the results of HOMO-LUMO energy gap. The calculated vibrational frequencies show that the most intense frequency was obtained to be 924.9862cm-1 at 146.7973KM/mole by RHF/3-21G in gas phase while at B3LYP/3-21G, it has the most intense frequency of about 474.1260cm-1 at 390.1077.2845MK/mole in methanol.Keywords: Optimixation, Methanol, Gas, Frequency, Tetracen

DFT, RHF and MP2 based study of the thermodynamic, electronic and non-optical properties of DNA nucleobases

Deoxyribonucleic acid or DNA is a molecule that contains the instructions an organism needs to develop, live and reproduce. These instructions are found inside every cell, and are passed down from parents to their children. In this study, the DNA nucleobases, that is. Adenine (A), Guanine (G), Cytosine(C) and Thymine (T) have been investigated by employing quantum chemical methods calculation. The thermodynamic parameters such as entropy, enthalpy, heat capacity and zero point vibrationional energy, non optical linear properties (dipole moment and mean polarizability) and Mullikan charges were calculated using Restricted Hartree–Fock (RHF), Moller-Plesset Second Order Perturbation Theory (MP2) and Density FuTheory (DFT), B3LYP and LSDA methods with 3- 21G, 3-21+G and 6-31G basis set . In addition, HOMO-LUMO energy gap of each of the molecules was calculated. The high value of HOMO-LUMO energy gap indicates the high stability of the molecules in chemical reaction. Of the four molecules, guanine has the highest value of HOMO- LUMO energy gap which implies that it is the most stable molecule in chemical reaction. The values of the dipole moment obtained were in agreement with the experimental values. For instance, the dipole moment of guanine at B3LYP/6-31G was calculated as 7.2D while the experimental value is 7.1D. Gaussian 03 package was used to perform all the calculations. Results from comparison of the DFT, MP2 and RHF methods shows close results and can be seen to support one another.Keywords: DNA, Nucleobases, HOMO-LUMO, DFT, RHF and MP

Development of Shunt Active Power Filter for Harmonic Reduction using Synchronous Reference Frame with Space Vector Pulse Width Modulation

The work aims at development of Shunt Active Power Filter (SAPF) for harmonic reduction. The current harmonics are being caused by nonlinear characteristic of power electronics based equipments which increase power losses and in turn reduce power quality. Synchronous Reference Frame (SRF) was used as a control strategy and for reference harmonic current generation and Space Vector Pulse Width Modulation (SVPWM) was adopted as switching signal generation. With RL load under balanced input voltage condition, the developed SAPF-SVPWM achieved a reduction of THD of 0.91% as compared to 25.60 before compensation. In addition, the developed SAPF- SVPWM model was compared with SAPF without compensation using RL load under unbalanced voltage and the result shows that the developed SVPWM achieved reduction in THD of 1.74 % as compared to 26.68% after and before compensation. The developed SVPWM model was also compared with SPWM balanced and unbalanced voltage condition. The results show that SVPWM performed better than SPWM. All the results obtained are within IEEE 519 harmonics standard (i.e. THD less than 5%) with nonlinear load under balanced and unbalanced voltage. Keywords: Shunt active filter, input voltage, harmonics, space vector pulse width modulation, nonlinear load

Influence of climate variability and change on natural hazard in selected states in northern Nigeria

The study examined the climate variability and change using temperature record (1951-2014) over Kano, Maiduguri, and Sokoto to depict the spatiotemporal influence on natural hazards across the states. Shiroro hydrologic records for thirty seven years (1975-2012) were collected and analyzed in addition, 300 structured questionnaires were administered to the residents of Gurmana downstream settlement for the purpose of generating their responses arising from flooding and its related problems. The result affirmed temperature changes between 1950 - 1981 and 1982 – 2014; it reveals positive changes in April mean, maximum and minimum temperature values of between 0.4 to1.5°C across the study area. Similarly, the observed oscillation and positive trend of inflow and outflow from shiroro reservoir constitute a major and unprecedented shift in stream flow across the downstream communities. Intensified warmer temperature, inflow and discharge trends have continued to aggravate seasonal rainfall related hazards which are threats to sustainability of human livelihood across most rural communities. Consequently, there is need for systematic development and application of policies, strategies and adoption of best practices as pathway towards disaster risk reduction

Reduction of Sulphur Content of Urals Crude Oil Prior to Processing Using Oxidative Desulphurization

The presence of sulphur in crude oil poses enormous challenges as regards its negative environmental and economic impacts. As such, the safety of the personnel and the equipment is at high risk during the processing of Urals crude oil in Kaduna Refining and Petrochemical Company (KRPC) because of its sour nature. This study was aimed at reducing the sulphur content of the Urals crude oil prior to processing by subjecting it to oxidative desulphurization where peracetic acid was used as the oxidant in the actual mass-to-stoichiometric mass ratio ranging from 1 to 5. The oxidized sulphur compounds were thereafter extracted using acetic acid as the extraction solvent. Furthermore, atmospheric distillation was carried out on both the raw and the desulphurized crude oil samples. Finally, the sulphur contents of the various crude oil samples and their fractions were analyzed. The results showed drastic reductions in the sulphur contents up to actual mass-to-stoichiometric mass ratio of 2 but the reductions became progressively insignificant afterwards. Meanwhile, the highest reduction in the sulphur content of the crude oil was 61.6 % while those of the gasoline, kerosene, diesel and residue were 32.0, 45.1, 68.9 and 75.0 % respectively. Therefore, peracetic acid is an effective oxidant for oxidative desulphurization of the crude oil.Keywords: Sulphur content, Crude oil, Oxidative desulphurization, Thiophenic compound