African Journals Online
Journal of Applied Science and Technology (JAST)

Volume 6 Nos 1 & 2, 2001
Abstracts

THE RELATIONSHIP BETWEEN THE ONE-OUTLIER DISPLAYING COMPONENT AND FISHER'S LINEAR DISCRIMINANT FUNCTION

B.K. Gordor and N.R.J. Fieller +Department of Mathematics and Statistics, University of Cape Coast, Cape Coast, Ghana.+ School of Mathematics and Statistics, University of Sheffield, Sheffield, UK.

The technique for displaying single outliers in multivariate data has been examined and the results show that there is a relationship between the one-outlier displaying component and the linear discriminant function. The nature of this relationship and the implications are also discussed.

DETERMINATION OF NUCLEAR CROSS-SECTION OF ⁸¹Br (n,) Br⁸² REACTION BY THERMAL NEUTRON IRRADIATION OF BARIUM BROMIDE

PROCESSED AND MEASURED AS HBr⁸².

K. Ahmad, L. Baranyai+, J. Kornyei+, and B.T. Maakuu

Ghana Atomic Energy Commission, P.O. Box LG.80, Legon, Accra, Ghana

+ Institute of Isotope Co. Ltd., Budapest, Hungary

The nuclear cross-section of the reaction ⁸¹Br (n,) Br⁸² has been measured by irradiation of Barium Bromide (BaBr₂) in a thermal neutron flux of 4.2 x 10¹³ n cm^-2 s^-1. The BaBr₂ was chemically processed and measured as Hydrogen Bromide (HBr⁸²). The value of nuclear cross-section was determined to be 2.1 0.2 barns, which falls within the range of values as previously reported elsewhere.

RAPID CALIBRATION OF THE CENTRAL CONTROL ROD OF MINIATURE SOURCE REACTOR (MNSR)

G.I. Balogun

Reactor Facility Section, Centre for Energy Research and Training, Energy Commission of Nigeria

Ahamdu Bello University, Zaria, Nigeria.

An innovative method of combining the well-known computer codes WIMS and CITATION in an interactive Windows environment to calculate the control rod worth and generate the calibration data/curve of single-contr-ol rod miniature source reactor (MNSR) types has been developed and tested. In the scheme, once CITATION base data have been prepared using group constants generated by WIMS, the required calculations are perform-ed automatically. The methodology eliminates errors and cumbersome procedures involved in manual regenera-tion of data after each CITATION pass associated with the calculations, thus facilitating the reactor design proc-ess, such that an important aspect of reactor design calculation that used to take days or weeks could now be more reliably done within the shortest possible time.

GAMMA RADIATION TREATMENT OF WASTE WATERS FROM

TEXTILE INDUSTRIES IN GHANA

S. A. Dogbe+, G. Emi-Reynolds and G. K. Banini

+Chemistry Department, Radiation Technology Center, GAEC, P. O. Box LG. 80, Legon

National Nuclear Research Institute, GAEC, P. O. Box LG. 80, Legon, Ghana.

Effects of gamma irradiation alone, and in combination with chemical treatment on color, odor, chemical oxyg-en demand (COD) and suspended solids in waste waters from textile industries in Ghana were studied to explore the potential of alternative and innovative processes for treatment of industrial waste waters. Waste waters from three textile industries in Ghana were progressively irradiated to a maximum dose of 19.96 0.07 kGy in a ga-mma irradiator of dose rate 7.80 0.05 kGy/h. The waste water samples were also irradiated in the presence of hydrogen peroxide, sodium peroxide, aluminium sulfate and ferrous ammonium sulfate. In a preliminary study, model aqueous solutions of three textile dyes were irradiated to investigate the process of treatment. Irradiation of waste water samples in the presence of ferrous ammonium sulfate were found to be an effective method for treatment of waste waters from the textile industries.

ANALYSIS OF TOTAL HYDROGEN CONTENT IN PALM OIL AND PALM KERNEL OIL USING THERMAL NEUTRON MODERATION METHOD

E.H.K. Akaho, S.A. Jonah, C.P.K. Dagadu+, B.T. Maakuu, S. Anim-Sampong, and A.W.K. Kyere

National Nuclear Research Institute, Ghana Atomic Energy Commission (GAEC),

P.O. Box LG80, Legon-Accra, Ghana.

+ Centre for Energy Research and Training, Ahmadu Bello University,

P.M.B. 1014, Zaria, Nigeria.

A fast and non-destructive technique based on thermal neutron moderation has been used for determining the total hydrogen content in two types of red palm oil (dzomi and amidze) and palm kernel oil produced by traditio-nal methods in Ghana. An equipment consisting of an ²⁴¹Am-Be neutron source and ³He neutron detector was used in the investigation. The equipment was originally designed for detection of liquid levels in petrochemical and other process industries. Standards in the form of liquid hydrocarbons were used to obtain calibration lines for thermal neutron reflection parameter as a function of hydrogen content. Measured reflection parameters wi-th respective hydrogen content with or without heat treatment of the three edible palm oils available on the mar-ket were compared with a brand cooking oil (frytol). The average total hydrogen content in the local oil samples prior to heating was measured to be 11.62 w% which compares well with acceptable value of 12 w % for palm oils in the sub-region. After heat treatment, the frytol oil (produced through bleaching process) had the least lo-ss of hydrogen content of 0.26 % in comparison with palm kernel oil of 0.44 %, followed by dzomi of 1.96 % and by amidze of 3.22 %.

TRANSIT DOSE CALCULATIONS AROUND STRAIGHT CATHETERS IN HIGH DOSE RATE (HDR) BRACHYTHERAPY

E.K. Nani, A.W.K. Kyere, G. K.Tetteh+ and E.K. Addison*

National Centre for Radiotherapy & Nuclear Medicine, Korle Bu Teaching Hospital,
P. O. Box KB 369, Korle Bu, Accra, Ghana.
+ Department of Physics, University of Ghana, Legon, Accra, Ghana.
* Dept of Physics, Kwame Nkrumah University of Science &Technology, Kumasi, Ghana

An analytical formalism is presented for the calculation of the transit dose in high dose rate (HDR) brach-ytherapy, and an example is provided to show the effects of the transit dose on the output. The transit dose, wh-ich is neglected by current computer software for calculating doses, could result in significant dosimetric errors since the additional unrecognised doses imply over-dosing and distortions in the dose distributions within the ir-radiated volume. Assessment of dose to critical and radiosensitive organs can be considered inaccurate and cou-ld increase late tissue complications as predicted by the Linear Quadratic Model. A model based on the hybridi-ised function has been developed for determining the transit dose in HDR brachytherapy, and the model works very well for straight catheters and is therefore recommended for the evaluation of the transit dose around such catheters.

GEOTECHNICAL CONSIDERATIONS OF PERENNIAL FAILURES OF A HIGHWAY SECTION OVER A BOX CULVERT IN A TROPICAL RAIN FOREST IN GHANA.

E.B.E. Ghartey and C.F.A. Akayuli

Council for Scientific and Industrial Research, Building and Road Research Institute,

CSIR-BRRI, P. O. Box 40, Kumasi, Ghana.

The causes of frequent failures of the Kumasi – Accra highway section at Wiwiso have been investigated to offer remedial measures on future reconstruction works. The study of the highway section at Wiwiso has revea-led that pavements can undergo considerable distress when seepage control considerations are partially or whol-lly neglected in the design and construction. Investigation of a box culvert constructed across the highway has established that the foundation had experienced negligible differential settlements and cracks had not developed in the sub-structures, but drainage control of the shoulders, up-slope sides, culvert/sub-base interface had been partially neglected thus prompting perennial failures of the pavement. It was observed that an inevitable feature of failures of pavements placed over concrete culverts was the development of undulations, cracks and pot-holes of large dimensions which had generated much public concerns. It is concluded that the major factors observed to influence the rate of pavement failures are age, sub-grade and sub-base material quality, inadequacy of seepa-ge conduits, partially surfaced shoulders, disturbed crowns through non-engineered maintenance works and non-appreciation of suitable precautionary measures to mitigate failures.

APPLICATION OF EARTH BUILDING MATERIALS FOR LOW-INCOME HOUSING

Nana Asamoah-Boadu and F.K. Afukaar

Council for Scientific and Industrial Research, Building and Road Research Institute,

P.O. Box UST 40, Kumasi, Ghana.

The characteristics, properties, problems and other factors associated with earth materials for building houses, especially in the tropical regions of the world are identified. The inter-relationships among these factors which inhibit the adoption of earth materials and the recommendations for overcoming the problems in a coordinated manner are discussed. The information and solutions provided would enable economic and appropriate measur-es to be taken to make earth buildings safer and more durable.

DEVELOPMENT OF A NATIONAL CODE OF PRACTICE FOR STRUCTURAL MASONRY – THE GHANAIAN APPROACH

Nana Asamoah Boadu and F.K. Afukaar

Council for Scientific and Industrial Research, Building and Road research Institute,

P.O. Box UST 40, Kumasi, Ghana.

The problems and constraints faced by most developing countries, particularly Ghana, in developing codes of practice for structural masonry are highlighted. The steps that must be undertaken through the coordinated efforts of the National Standards Boards, Research Institutions, Universities and Professional Bodies in the con-struction industry to formulate technical specifications and standards aimed eventually at the development of a national code of practice for structural masonry are also outlined. Education and training of brick and block lay-ers, and local manufacturers of masonry units have been identified as key measures needed to ensure high quali-ty masonry products in Ghana. A proposed format of draft code of practice is also presented.

A NEW CLAMP METHOD FOR FIRING BRICKS

K. Obeng and J.K. Boadi

Council for Scientific and Industrial Research, Building and Road Research Institute, (CSIR-BRRI)

University P. O. Box 40, Kumasi, Ghana.

A conventional or standard clamp firing method has long been used by small and medium scale brick industries in Ghana, because the system is easier to build, cheaper to operate, can be constructed close to the supply of cl-ay and fuel to reduce transportation cost, and has a higher brick capacity of between 5.0 x 10³ to 1.0 x 10⁵ green bricks than other systems. Despite these advantages, the conventional clamp firing method suffers from excessi-ve heat loss from the top of the clamp due to thermal convection, and the uncontrolled heat loss in the firing has led to higher number of under-burnt bricks. To overcome this operational deficiencies, a new method of firing bricks that uses brick clamp technique that incorporates a clamp wall of 60 cm thickness, a six tier approach of sealing the top of the clamp (by combination of green bricks) has been developed. The new method of sealing the top of the brick clamp greatly reduces heat loss by convection from the top of the clamp and the sides of the clamp wall resulting in the reduction of under-burnt bricks by 6.9 %.

A ONE-DIMENSIONAL MODEL FOR SIMULATING SOIL WATER MOVEMENT

J.D. Owusu-Sekyere, E.A. Baryeh, S. Pengà & X.H. Shaoà

Department of Agricultural Engineering, University of Cape Coast, Cape Coast, Ghana

à Irrigation and Drainage Department, Hohai University, Hohai, China

Two simulation models have been used to predict water movement in soil and soil water content in a wheat field at Guan Yun (China). A backward finite difference approach was used to solve for the upward water flux and the water movement under a water table control system. It was found that the upward water flux decreased non-linearly as the water table depth (depth below root zone) increased, and a regression analysis revealed the relati-onship to be exponential. The values of calculated and measured soil water content and total evapotranspiration decreased with number of days after rain or irrigation. The nodal soil water content also decreased with the soil depth.

X-RAY POWDER DIFFRACTOMETRY, CRYSTALLOGRAPHIC PHASE ANALYSIS AND LATTICE PARAMETERS OF KAOLINITE.

F.A. Gavu and A. Ayensu +

Department of Physics, University of Cape Coast, Cape Coast, Ghana

+Industry, Natural and Social Sciences Sector, Council for Scientific and Industrial Research

CSIR, P.O. Box M32, Accra. Ghana.

Computerized X-Ray diffraction system has been used to determine the composition and lattice parameters of raw and activated kaolinite. The universal diffractometry URD 63 was interfaced with computer via an APX 63 software package for rapid capturing of data on reflected intensity and other crystallographic parameters, includ-ing atomic coordinates, lattice parameters, Bragg angle and structure factor. Neglecting impurities, the raw kao-linite sample was found to contain about 55.6 % silica and 44.4 % alumina. The diffraction traces and intensity peaks of the thermal and chemical activated kaolinite indicated respectively, reduction in silica and alumina content.

X-RAY DIFFRACTION STUDIES OF Cd_0.9Zn_0.1Te AT ROOM TEMPERATURE

R. K. Nkum and R. B. Weil+

Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

+ Solid State Institute and Department of Physics, Technion-Israel Institute of Technology,

32000 Haifa, Israel

X-ray diffraction studies of Cd_0.9Zn_0.1Te have been made from the diffraction patterns recorded at room tempera-ture. A distinct splitting of some of the lines in Cd_0.9Zn_0.1Te have been found while no splitting was found in the lines for CdTe, giving evidence that the structure of Cd_0.9Zn_0.1Te is distorted from the zinc blende structure. Correcting for thermal vibrations, it is observed that the intensities of the diffraction lines of Cd_0.9Zn_0.1Te at ro-om temperature were lower than those of the lines of CdTe. This gives further evidence of the distortion in the structure of Cd_0.9Zn_0.1Te. The results of the X-ray diffraction studies indicate that the structure of Cd_0.9Zn_0.1Te at room temperature is zinc blende with a rhombohedral distortion. A model in which the Te ion is shifted from its original position is consistent with the results.

POLLUTANT CONCENTRATION AND DISPERSION IN ENGINE TEST LABORATORIES

K.D.H. Bob-Manuel

Department of Marine Engineering, Rivers State University of Science & Technology

P.M.B. 5080, Nkpolu, Port Harcourt, Nigeria.

Concentration levels of nitrous fumes (nitric oxide and nitrogen dioxide) and carbon monoxide in engine test la-boratories during performance test and simulated dispersion values of these pollutants are presented. The simul-ation was based on solution of three dimensional Gaussian diffusion equation of dispersion in the laboratories at standard atmospheric conditions. The predicted values were in agreement with the measured concentration lev-els. It was observed that concentration levels of nitrous fumes and carbon monoxide in the laboratories varied during the test period. Engine design, operational mode, calibration gas concentration and ventilation were ide-ntified as variable factors that could influence the concentration levels of pollutants in the laboratories. High co-ncentration levels of pollutants occurred immediately after calibration of analyzers, during long idling and at hi-gh speed and load operation when ventilation in the test cell was inadequate.

IMPACT OF DEVELOPMENT AND URBANISATION ON VARIATION OF WATER QUALITY PARAMETERS OF THE NIMA CREEK IN ACCRA

E. Nana-Amankwaah and E.K. Bosque-Hamilton

Council for Scientific and Industrial Research, Water Research Institute (CSIR-WRI)

P. O. Box M32, Accra, Ghana.

The spatial and temporal variations of the physico-chemical water quality parameters, microfauna and micro-flora composition of the Nima Creek in Accra vividly illustrate the environmental problems associated with water bodies in a community where development and urbanization are in progress. Monthly water and benthic bedload sampling were undertaken to determine the water quality and biological constituents of the creek from a point near the source to the confluence with the River Odaw. The study reveals two distinct zones of variable water quality parameters. The upstream section covering a low population density area which is not very much affected by anthropogenic activities, was marked by comparatively high Dissolved Oxygen (DO) level, low Bio-chemical Oxygen Demand (BOD) level, and high incidence of micro-organisms associated with oligosaprobic waters, such as Ulothrix, Phiodina rotifer, Gyrosigma and Navicula species. The upstream section of the creek could be described as comparatively unpolluted sections with good quality water. The middle and downstream sections covering the densely populated and low income areas of the catchment area had comparatively high BOD ranging from 120.0 to 609.0 mg/L, depleted DO ranging from 0.0 to 9.1 mg/L and pollution-tolerant orga-nisms like Vorticella, Synedra, Synura, Paramecium and Oscillatoria species. The values of physico-chemical and biological water quality parameters indicate unusual stress on the water quality in the middle and down-stream sections of the creek, which confirms the negative impact of high population density, slum and poor env-ironmental sanitation on water bodies.

NUTRITIONAL VALUE AND CHOLESTEROL-LOWERING EFFECT OF WILD

LETTUCE (LAUNAEA TAXARACIFOLIA) LEAF AS A SOURCE OF PROTEIN

P.A. Wallace, E.K. Marfo+, G. Timpohà and W.A. Plahar¤

Council for Scientific and Industrial Research, Animal Research Institute,

P. O. Box AH 20, Achimota, Ghana,

+Methodist University College, Accra, Ghana

àDepartment of Horticulture, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana,

¤ Council for Scientific and Industrial Research, Food Research Institute,

P. O. Box M20, Accra, Ghana

The nutritive value and cholesterol-lowering effect of wild lettuce (Launaea taxaracifolia) leaf when fed as a source of protein was assessed by using male albino rats (Rattus norvegicus) as an index of evaluation. The rats were fed on both methionine supplemented and unsupplemented wild lettuce leaf diets and elicited significant plasma hypocholesterolemic response (p < 0.05) at all levels of inclusions. There were no significant differenc-es in the cholesterol levels as determined in some visceral organs namely liver, kidney and heart of animals fed on the wild lettuce diets (p > 0.05). Total lipid levels determined in the liver, kidney and heart of the animals fed on both wild lettuce leaf protein diets and casein-based diets (as control) were comparatively similar. However, lipid levels in the plasma of the animals maintained on the wild lettuce diets were significantly higher than those fed on the casein diets (p < 0.05). Total plasma protein was not affected by feeding animals with wild lettuce leaf. However, the rats fed with the lettuce leaf diets (both methionine supplemented and unsupplemented) gai-ned comparatively lower growth response in terms of weight gain, protein efficiency ratio (PER) and feed effici-ency ratio (FER) when compared with animals on the respective control diets (p < 0.05).

TRENDS AND ADVANCES IN PESTICIDE RESIDUE ANALYSIS

P. O. Yeboah

Department of Chemistry, National Nuclear Research Institute

P. O. Box LG80, Legon-Accra, Ghana.

The nature, origin and the economic significance of pesticide residues are reviewed to underscore the need for countries to develop the ability and capacity to monitor pesticide residues. An overview of pesticide residues analytical procedures is also presented with emphasis on thin layer chromatography (TLC) as an important tool for analysis. Where limited budget does not permit the use of more expensive and sophisticated equipment, su-ch as gas chromatography and high performance liquid chromatography, TLC is recommended for use.

DETECTION OF PESTICIDES IN THIN LAYER CHROMATOGRAPHY

P.O. Yeboah, S. Lowor + and C.K. Akpabli à

Chemistry Department, National Nuclear Research Institute, P. O. Box LG 80, Legon, Ghana

+ Cocoa Research Institute of Ghana, CRIG, Tafo, Ghana.

à Department of Chemistry, University of Ghana, Legon, Ghana.

O-Tolidine plus potassium iodide, p-nitrobenzene-diazonium-fluoroborate bioassay with enzyme sources, silver nitrate plus ultraviolet radiation, and p-dimethyl-aminobenzaldehyde and photosynthesis inhibition modes of de-tection were selected for Thin Layer Chromatography screening of pesticides residues of reference origin. Sing-le solvents were used for elution and indicator compounds used for controlling the proper conditions for the det-ection. The detectability of 34 pesticide compounds was tested and the minimum detectable amounts were dete-rmined. The linear range of some of the pesticides relative to the detection methods used is also presented. Re-sults indicate that the linear range of a particular chemical depends on the method of detection used. The range was found to be wider for chemicals that had very low limits of detection with particular methods.

BREEDING FOR DROUGHT TOLERANCE IN CROPS

H.K. Adu-Dapaah and E.Y. Oppong-Kunadu +

Council for Scientific and Industrial Research Institute,

Crop Research Institute, P. O. Box 3785, Kumasi, Ghana

+ Crop Research Institute, Pokuase Station, P.O. Box AM 184, Accra, Ghana.

Tolerance to drought is under complex genetic control and selection for it often presents difficult challenges to plant breeders. With classical breeding methods, combining or pyramiding many different desirable genes in one background is nearly impossible because the tests required to reveal the presence of those genes in the off-spring are not available. The objective of this paper is to review the various approaches employed by research-ers to develop drought tolerant varieties of crop plants with emphasis on the potential of biotechnological techn-iques in addressing this concern. Screening methods for field evaluation, physiological evaluation and the use of molecular-genetic techniques have been outlined. The use of biotechnological methods provides the most op-timistic means of detecting the presence of genes conditioning drought tolerance. Biotechnological techniques also provide a better understanding of the genetic control of complexly inherited traits and lead to the developm-ent of markers that could enhance breeding for drought tolerance. Molecular markers such as isozymes, storage proteins, restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD), provide powerful means of identifying genetic loci associated with drought tolerance for use in marker-assisted selection (MAS). The development of saturated molecular genetic maps could lead to detection of markers sig-nificantly associated with quantitative trait loci (QTL) that determine drought tolerance, which could make sele-ction for drought tolerance more effective than conventional phenotypic methods.