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Fabrication of dye-sensitized solar cells using anthocyanidins from the extracts of Roselle (Hibiscus sabdariffa).
Get PDFThis study extracted, purified and applied the extracts of H. sabdariffa as photo-sensitizers in dye-sensitized solar cells. The chemical properties of the extracts were examined using UV, FT-IR and GC-FID spectroscopic studies. The photoelectrochemical properties of the extracts were also reported. U-V spectra showed significant difference in the absorbance and wavelengths of the crude and purified samples of H. sabdariffa (HSE and HSP respectively). The former has characteristic absorptions of 1.096 at 330 nm and 0.211 at 540 nm, and the latter, 0.211 at 335 nm and 0.334 at 540 nm. Shifts in the wavelengths of the absorption (around 330 - 350 nm) and a characteristic decrease in the absorption between the HSE and HSP were observed. The FT-IR spectra of the HSE and HSP have similar characteristic absorbances peculiar to OH, C=O, C-C double bond (both aliphatic and aromatic) and C-O HSP has two additional absorbances at 2365 cm-1 and 2075cm-1. The spectra of the purified sample have bathochromic (red) shifts on the hydroxyl group and hypsochromic (blue) shifts on the benzene. The GC-FID chromatograms revealed the presence of six anthocyanidins and the spectra data showed the amount of the anthocyanidins in mg per 100 g of the sample. The results showed that delphinidin was in abundance, followed by cyanidin in both samples. The quantities of the delphinidin increased with purity of the samples, while the others decreased with purity for both samples. The photovoltaic performances of HSE and HSP have the fill factors of 0.254 and 0.347 and the overall efficiencies of 0.118% and 0.645% respectively. From these data, the purified sample has higher fill factor and efficiency than the unpurified extract.
Keywords: Anthocyanins, dye-sensitized, solar cell, extracts, fill factor, efficiency
Comparative Studies of Water and Sediment Qualities of Some Dams in Kwara State
Get PDFPotable water is becoming progressively scarce due to anthropogenic pollution and it has necessitated monitoring of water quality of rivers and dams as a subject of ongoing concern and research. This study was conducted to assess the quality of water collected from four different dams (Agba, Igbaja, Oloru and Omu-Aran) in Kwara State, Nigeria using standard procedures. Water and sediment samples were collected from three different spatial locations on the dams. The average values of most physicochemical parameters like pH, temperature, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Total Dissolved Solid (TDS), Total Hardness (TH), Alkalinity, some nutrients such as chloride (Cl-), sulphate (SO42-), phosphate (PO43-), nitrate (NO3-) and some heavy metals such as Cu, Zn have values that were within World Health Organisation (WHO) guidelines for drinking water for each of the dams while Cd and Fe concentrations were observed to be much higher than WHO guidelines for drinking water. This could be as a result of anthropogenic input. The dams’ sediments analyzed for heavy metals showed that Mn, Zn and Cd were high in the dams, which can be easily washed into the water body through leaching, thereby causing detrimental effect to the consumers.
Keywords: geo-accumulation index, bioavailabilty, nutrient, dam, alkalinity
Study of Surface Modification of Electrospun Polyethylene Oxide Composite Fibre
Get PDFFunctionalization of polymers had gained attention because of advance applications as sensor, energy devices, membrane, etc. This present study is aimed at studying surface modification as a result of electrospinning functionalized polyethylene oxide (PEO) with zinc ion Zinc chloride was added in various proportions to PEO solution then electrospun at various voltage. Fibres resulted into various shapes; belt, rod, mat and thread which differs from the primary PEO. The mechanism for the morphology modification was studied and the optimum conditions which retain the fibrous morphology were noted. This functionalized PEO can be used as energy device.
Keyword: Polyethylene oxide, Modification, Fibre, Composite, Functionalize
Fuzzy Bigroup from another Viewpoint
Get PDFIn group theory, given two groups G and H, it is possible to construct a new group from the Cartesian product of G and H, G × H. With this as a motivation, we replicate this concept in fuzzy group algebra. In this paper, we take a slight deviation from the familiar definition of fuzzy bigroup by looking at fuzzy bigroup from the idea of Cartesian product of groups. We define Cartesian fuzzy function on groups and give examples. We also define Cartesian fuzzy bigroup and study some of its basic properties.
Keywords: Bigroups, Cartesian fuzzy function, Fuzzy bigroups
Good Governance and Economic Prosperity in Sub-Saharan Africa: The Islamic Perspective
No full textFor any nation to experience growth and accelerated development, conscious efforts have to be made in terms of socio-economic inclusion of the entire citizenry, good governance and ensuring justice in all spheres. This paper advocates some Islamic elements of governance and economic blueprint as panacea for development that will culminate to a harmonious communal living devoid of sectional schisms and economic exploitation of the majority by the few. The Islamic institutions of Zakaat (Compulsory Annual Charity), Sadaqah (Voluntary Alms), Kaffaarah (Atonement Feeding) and Zakaatul-Fitr (End-of-Ramadhan Charity) that are effective instruments of redistribution of wealth and bridging the gap between the affluent and the destitute were proposed for adoption by Sub-Saharan Africa in order to achieve the much sought national reconciliation, economic prosperity and survival justice for all. The paper concludes that it is only through good governance and economic emancipation of people that genuine progress and real nationhood can be achieved. Keywords Good governance, Sadaqah, economic prosperity, Zakaat, Zakaatul-Fitr, empowermen
Gas Chromatography-Mass Spectrometry and Cytotoxicity of Securidaca longepedunculata (polygalaceae) Root Bark Extract
Get PDFSecuridaca longepedunculata is a savannah shrub found growing in tropical Africa. It is reputed to have more than a hundred medicinal uses and is a major component of anticancer decoctions in Nigeria. Despite its reported use as an anti-cancer plant, there is a dearth of information on the anti-cancer potential and mechanism of its anticancer activity. The present study is to identify the chemical constituents present in Securidaca longepedunculata by quantitative Gas Chromatography-Mass Spectrometry (GC-MS) analysis and determine the cytotoxic effect of the plant on Ehrlich ascites carcinoma cells. Secondary metabolites in the extract were predicted using GC-MS. In vitro cytotoxic activity was determined using the trypan blue dye exclusion assay by incubating Ehrlich ascites carcinoma cells with various concentrations of S. longepedunculata aqueous extract. Analysis by GC-MS revealed the presence of the following compounds: bis (2-ethylhexyl) phthalate (90.99%), 1-decanol (4.17%) and cyclododecane (1.86%), phenol, 2, 21-methylene bis (1.32%), cyclopenten-4-one, 3-hydroxy-1, 2, 3, 5, 51-pentakis (trimethylsilyloxy)- (0.89%) and phenol, 2, 4-bis (1, 1-dimethylethyl)(0.78%). Securidaca longepedunculata aqueous extract (SL) was cytotoxic to Ehrlich ascites carcinoma cells in vitro. The IC50 of SL on EAC cells was 67 μg/ml. The aqueous root-bark extract of S. longepedunculata contains bioactive agents and was cytotoxic to Ehrlich ascites carcinoma cells in vitro.
Keywords: phthalate, Ehrlich, carcinoma, medicinal, plant
Orthogonal-Based Second Order Hybrid Initial Value Problem Solver
Get PDFThis work focuses on development of an initial value problem solver by employing a new class of orthogonalpolynomial, the basis function. We present the recursive formula of the class of polynomials constructed and adopt collocation technique to develop the method. The method was analyzed for its basic properties and findings show that the method is accurate and convergent.AMS Subject Classification: 65L05, 65L06
Keywords: Orthogonal polynomials, Algorithm, Block method, Collocation, Interpolation, Zero-Stable
Modelling and Simulating Access Control in Wireless Ad-Hoc Networks
Get PDFThere has been a great increase in the use of wireless networks over the years; Mobile Ad hoc Network is an example of such wireless network. It functions without any central administration and the network is made up of a collection of nodes within a radio frequency. Security in mobile network has been an area of great research over the years mainly because most ad hoc protocols do not provide the basic security framework and services. This paper aims at simulating access control in wireless ad-hoc networks. The objectives are to ensure that the network is not vulnerable and should also devoid of any form of malicious attack that could prevent authorized access. Two metrics (packet delivery ratio and traffic overhead) were used to measure the effectiveness and efficiency of the networks. Through a detailed simulation study, we show that the protocol is efficient and allows a trade-off between security and performance. This research focuses on designing an access control mechanism that was incorporated within ad-hoc routing protocols with the aim of adding an extra layer of security against threats in the network. The three stage-process for access control was implemented with NS-2 v 35. The nodes in the simulation were created dynamically, the movement between nodes was generated randomly and the connections between the nodes were done using Constant Bit Rate (CBR) connection which was aimed at enabling the network to mimic a real life scenario. Through different experiments and simulations done, it was observed that the access control model works and also provides a higher level of security for ad-hoc networks even when under security threats and attacks.
Keywords: Access control, NS 2, Ad-Hoc, MANET, Mobile, Simulation
Effect of Performance Management System on Employees’ Attitude in the Nigerian Banking Sector
No full textPerformance Management System is said to have been developed and implementedresulting in the failure to deliver the results people expect from it. The main objective of the paper is to examine the effect of Performance Management System (PMS) on Employees’ Attitude in the Nigerian Banking Sector. Stratified Sampling Technique were used to select a total number of 180 staff from Head Offices of the 15 listed Banks in Nigerian Stock Exchange (NSE). Primary data were collected using a structured questionnaire. Data obtained were analysed and presented using both descriptive and inferential statistics. Correlation and regression analysis were used to test the hypotheses formulated for the study. The findings revealed that R2 of 0.2177, 0.4066 and 0.6687 values suggested that variables in the model are all jointly significantly influence the probability of the Nigerian banking sector performing better. The study concluded that the implementation of PMS is said to be the commencement of changed attitude to work due to continuous and systematic assessment of employees’ performance on a regular basis. The study recommended that; management should continue to communicate the importance of Performance Management System (PMS) to employees until the process is entrenched.Keywords Performance management, performance management system, employees, attitude,Nigerian banking sector, performance indicator Â
NEPAD and Foreign Direct Investment in Africa
No full textThe New Partnership for Africa\u27s Development is a pledge by African Leaders based on a common vision and a firm, shared conviction that they have a pressing duty to eradicate poverty and place their countries, both individually and collectively on a path of sustainable growth and development and to participate actively in the world economy and politics (NEPAD, 2001). The paper uses the political economy theory to examine the philosophy of the New Partnership for Africa\u27s Development and the policy has been able to attract foreign direct investment. The research relies on secondary sources of data for the purpose of evaluating the successes and failures of NEPAD. The paper recommends that regional integration be strengthen to enhance economy interaction among African States and conflict prevent mechanism be strengthen to reduce persistence conflict in Africa, to encourage foreign investment in the region. KeywordsNEPAD, Foreign Direct Investment, development, poverty, underdevelopmen