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On the Interaction of Zinc with a Ferric Oxyhydroxide
(1985) Agyeman, Boadi Ankomah
Sorption and desorption of Zn by synthetic goethite (α-FeOOH) (surface area 95.2 m2/g, pH(PZC) 7.9) was studied in equilibrium and non-equilibrium conditions as functions of aqueous solution Zn and Mg concentrations and temperature, but at low amounts in the systems. The sorption data were analyzed with a multi—site Langinuir expression, which suggested that at pH 4.6 and 5.4 (25°C) Zn sorption could be entirely ascribed to a low capacity, high affinity site, whereas at pH 5.4 (44°C) and higher pH’s (both. 25 and 44°C) sorption could be described by two sites. At p118.5 (44°C) the data fit a model consisting of a high affinity Langmuir site coexisting with a site or mechanism following Henry’s Law. Site 1 affinity term, k1, increased with pH and temperature, but was not affected by 25 ppm Mg above pH 5.4. Log k1 was highly correlated with log K0, the thermodynamic distribution coefficient. Site 1 capacity term, b1, increased with pH up to pH 7.0 and then remained constant; it was not affected by either Mg or temperature. Site 2 affinity term, increased with temperature; at 25°C it did not vary with pH below pH 7.8, but increased four—fold at pH 8.5. Site 2 capacity term, b2, increased with both temperature and pH, and only below pH 7.0 were this parameter and decreased by 25 ppm Mg. At pH 5.4 though Mg did not affect k1, a decrease in b1 by Mg indicated some Mg ions were specifically adsorbed at site 1. However, the higher specificity of site 1 for Zn above pH 5.4 eliminated Mg effect on b1. Generally 25 ppm Mg significantly decreased Zn sorption at site 2 below pH 7.0. The sharp increase in Zn sorption with increasing pH in the pH range 5.4 -7 was attributed to the development of site 2 at pH 6.2, suggesting sorption by a second mechanism. Kurbatov plots suggested that one mole of H+ was released per mole of Zn sorbed below pH 7, and 2 moles above pH 7. A Zn (OH) 2 precipitation mechanism above pH 7.8 was emphasized by the release of 2 moles of H+ per mole of Zn sorbed in kinetic studies. Total sorption of Zn was markedly endothermic at all pH levels, the increase in sorption with temperature being most pronounced at low pH’s and high system loadings. Mean ∆G-0 values ranged from -9.1 kcal/mole at pH 5.4 to -11.2 at pH, pH 8.5, ∆H-0 from 14.5 kcal/mole at pH 5.4 to 6.5 at pH 8.5, and ∆S-0 from 76.9 cal/deg. mole at pH 5.4 to 57.7 at pH 8.5. Isosteric heats of Zn sorption, Qr , ranged from 1 to 27 kcal/mole, and were generally higher at low pH. Hysteresis was observed in desorption versus adsorption isotherms. Sorption was fast at pH 7.8 and 8.5, steady states being achieved in 2 hours. At pH’s below 7.8 a slow reaction followed an initial fast reaction. Below pH 7.8 the initial sorption reaction was nonprotolytic followed by a slow protogenic reaction.
The chemical constitution of seed fats from some selected plant families in Ghana
(1988) Tuani, Gideon Kwami
A total of ten seed fats from four plant families, namely sapindaceae, Sapotaceae. Olacaceae and Flacourtiacae have been analyzed for their acylglycerides’ composition. The component free fatty acids and their methylesters from each seed fat have boon separated quantitatively on thin layer chromatography (TV) and identified by their retention times relative to authentic standards. The infra red spectra of the separa-ed free fatty acids and their methylesters were also run and compared with those of authentic standards. Hydroxamic acid derivatives of the fatty acid methylesters have also been prepared and their melting points determined and compared with standards. Each glyceride fraction was digested with pancreatic lipase (enzymatic hydrolysis) to determine the relative positions of acyl groups in the glyceride. Putting the results obtained from all these analyses together, the most probable structures of the component acylglycorides in each seed fat have been proposed.
The genetics of maturity and its correlated traits and stability analysis in maize (zea mays l.) (a) identification of genomic regions controlling maturity and its correlated traits in b73 x unadapted mexican maize population. (b) evaluation of genotype by environment interactions in maize.
(2001) Abdulai, Mashark Seidu
This study was conducted to (i) apply biotechnological approaches. viz simple sequence repeats (SSR) primers and restriction fragment length polymorphism (RFLP) probes with classical breeding procedures to identify genes important in adapting exotic maize germplasm, and (ii) understand the mode of inheritance of maturity in adapted by unadapted F2 maize population. Two hundred and eleven (211) S1 families developed from a cross between adapted Corn Belt maize inbred line (B73) and an unadapted maize population and their testcrosses were evaluated at two planting dates and two locations, respectively, in 1995. Maturity was quantitatively inherited, and few factors were responsible for its expression in maize. Earliness was dominant to lateness. Fingerprinted DNA isolates from each family with SSR primers and RFLP probes revealed that, putative quantitative trait loci associated with maturity were located on seven of the ten chromosomes. Phi085, Phi 113, Phi014, Pigmentation umc59, umc168 and bnl5.09 were associated with maturity. The gene effects of the markers were a combination of additive and dominance. Ear and plant height were also quantitatively inherited and were linked to Pigmentations umc59, umc34, csu5, phi014, bnl5.09 and bnl7.49. Pigmentation, csu25, phi0l4, bnl7.49 and umcl09 were also associated days to anthesis, grain moisture at harvest and grain yield in testcrosses. The use of molecular markers in conjunction with classical breeding methods was an efficient approach to understanding the mode of inheritance of maturity in maize.
An autoregressive time series model of measles propagation: a case study of the Kumasi District
(2001) Nsiah, Dominic
In 1985, the Government of Ghana assisted by the World Bank and other organizations, initiated a programme of mass vaccination aimed at eradicating six childhood killer diseases namely, measles, poliomyelitis, whooping cough, diphtheria, tuberculosis and tetanus. In this study we attempt to assess the effectiveness of this intervention for the particular case of measles incidence in the Kumasi District. Using the Box-Jenkins method we obtain autoregressive (AR (2)) models of the pre intervention data, post intervention data and the entire interrupted times series data. Further, using interrupted time series analysis, we are able to show that the parameters before and after the intervention were significantly different at the 5% level of significance. In particular, the intercepts of linear trend lines were 27.56 and 29.04 cases per month before and after the intervention respectively. The slopes were —0.084 and -0.130 cases per month before and after the intervention respectively. The methods used in this study can clearly be used to investigate the effectiveness of any intervention aimed at controlling some time dependent natural or socio-economic phenomena.
Female genital mutilation and obstetric sequelae in the Upper East Region of Ghana
(2005-11-03) Odoi-Agyarko, Kwasi Dr.
Large-scale evidence regarding the social, psychosexual and medical consequences of Female Genital Mutilation (FGM) is lacking despite the numerous resolutions and recommendations that have been made, aimed at the elimination of FGM. The available evidence suggests that women with FGM may be more likely to suffer adverse obstetric outcomes than women without FGM. The hypothesis posed for this work was to examine the risk of adverse obstetric outcomes for each type of FGM (FGM type I, FGM type II, FGM type III and FGM type IV) compared with that in women without FGM, adjusting for study centre and other potential confounding factors. The study was a multi-centered prospective cohort study, based at the maternity units and obstetric departments of the Bolgatanga, Bawku and Navrongo Hospitals. Based on a pilot study, it was estimated that approximately 6,000 women would be required in order to detect a two-fold increase in the risk of outcomes such as stillbirth and early neonatal death, in women with each type of FGM, compared to women without FGM. A total of 6,413 consenting women with singleton pregnancies presenting for delivery were consecutively recruited into the study from December 2001 to June 2003. Subjects were followed through labour and delivery, and obstetric outcome, including duration of labour, instrumental delivery, episiotomies, perineal tears, post-partum haemorrhage and maternal deaths were recorded. The newborn infant was examined and vital status, APGAR score, birth weight, and other anthropometric data were also recorded. Subjects were followed up at the two-week and at the six-week post-partum period to ascertain the presence of complications such as genital wound infections and fistulas. After the data had been carefully checked, cleaned and edited, they were analyzed using STATA (version 8.2) and Statistical Package for Social Science (SPSS) (version 11). The results were presented in frequencies, cross-tabulations and univariate and multivariate analyses by logistic regression adjusting for confounding. Overall, the FGM prevalence was 38%, made up of 7% of FGM type I, 30% of FGM type II and 1% of FGM type III. Bawku had the highest FGM prevalence of 82% and accounted for 84% of all the cases of FGM Type III that were seen. FGM was significantly associated with prolonged labour (odds ratio: 1.47, p = 0.000, CI = 1.23 - 1.75). FGM had a direct relationship with post-delivery fistulas. The association between FGM type I and FGM type II was however not significant but FGM type III with odds ratio of 33.08, p-value = 0.000, CI of 5.95 to 184.09 was strongly associated with post delivery fistulas. FGM type II and type III were significantly associated with post-delivery genital wound infection. FGM type III with odds ratio of 38.03, p-value of 0.003, CI of 3.36 to 430.85 was strongly associated with post-delivery genital wound infection. FGM Type III with odds ratio of 453.16 and a p-value of 0.000 was strongly associated with third degree tears. FGM type III with odds ratio of 2.7 and a p-value of 0.003, CI of 1.39 to 5.24 was significantly associated with low APGAR score. FGM type I and FGM type II did not demonstrate any association with C-section; FGM type III (odds ratio3.12, z-statistic 3.76, pO.000, C11.75 - 5.86) however was significantly associated with C-section. FGM had only a mild association with Post-Partum Haemorrhage. FGM had no direct relationship with Cephalo Pelvic Disproportion, maternal death, extended stay in hospital after delivery, low birth weight and stillbirth. Location of residence, age, number of births, level of education and household wealth all interact. The increased risk of adverse obstetric outcomes with FGM observed in the study occurs against the background of increased maternal morbidity and mortality. This means that FGM is likely to be responsible for substantial numbers of additional causes of adverse obstetric outcomes. Adverse obstetric and perinatal outcomes can therefore be added to the known harmful immediate and long-term effects of FGM.
Management of the African grasshopper, zonocerus variegatus (l.) (orthoptera: pyrgomorphidae) in ghana: the role of chromolaena odorata
(2005-11-03) Timbilla, J. A.
The pestilence of the variegated grasshopper. Zonocerus variegatus, was investigated whether it was attributed to the introduction and spread of the weed. Chromolaena odorata in Ghana. and the consumption of pyrrolizidine alkaloids (PAs) from the flowers of the plant by the insect. The study was aimed at developing an effective control measure against the pest. Questionnaire and ecological surveys were conducted to determine the distribution patterns and densities of’ the insect and plant in different ecological zones in the country. traversing natural vegetations. Studies were conducted on the biology of Z. variegatus with respect to diet with and without source of PAs. The attraction of Z. variegatus to the PAs in the dry roots of C. odorata. Heliotropiurn indicum and Crotalaria refusa were compared while Carbofuran® 3G. Perfekthion® 40 EC and Karate® 2.5 EC were screened for their efficacy as killing agents for the grasshopper. The survey results established a correlation between the distribution of C. odorata and the pestilence of’ Z. variegatus. While Z. variegatus is distributed nationwide. C. odorata has spread as far north as Lat. 8º 30’ N from the Coast, an increase of 15’ within a decade. In areas with no C. odorata, Z. variegatus was univoltine and not a serious pest. However, below Lat. 8º 30’ N where C. odorata occurs, Z. variegatus exists in two distinct wet and dry season populations with the dry season population being a major pest on food crops and forestry products. This observation was traced to the pharmacophagous utilization of PAs horn the flowers of C. odorata during the dry season by the insect. The diet studies showed that Z. variegatus utilises PAs which are secondary plant metabolites. Diet with a PA-source as a component positively enhanced growth. egg production and life-span of the grasshopper. All stages of the insect were attracted to the PA-sources and 300 g weight of the dry chopped roots of C. odorata showed promise for use as the PA-lure component for the development of PA-based attracticide to manage Z. variegatus. Incorporating 1.0% Carbofuran® 3G (w/v) into the dry chopped roots of C. odorata yields a potent cost effective PA-based attracticide for the management of Z. variegatus in open fields and on cabbage. Thus, farmers at the community level can adopt this management option as a contribution to the management of’ Z variegatus. Notwithstanding the present achievement on the use of PA sources as attractants for the integrated management of’ Z variegatus, it. is conceded that further investigations on the biology and the development of PA-based attracticide baits with both chemical and biological insecticides for the management of Z. variegatus are required.
Diversity within yeast involved in spontaneous fermentation of pito
(2007-11-11) Glover, Richard Lander Kwame
A survey was conducted in ten (10) “Dagarti pito” production sites located in nine towns within eight administrative regions of Ghana to investigate diversity within yeast varieties involved in the spontaneous fermentation of Dagarti pito. Samples of dry yeast were obtained from commercial Dagarti pito producers from Tamale and Nyankpala (Northern Region); Ayigya- Kumasi and Monaco-Kumasi (Ashanti Region); Accra (Greater- Accra Region); Cape Coast (Central Region); Takoradi (Western Region); Sunyani (Brong Ahafo Region); Ho (Volta Region) and Suhum (Eastern Region). For purposes of comparison, dry yeast was also sampled from three dolo production sites in Ouagadougou, Burkina Faso. Yeast populations ranged between 106 and 108 cfu g-1. Twenty-five yeast isolates from each site were characterized phenotypically by colony and cell morphology as well as carbohydrate assimilation profiling, using the API ID 32 C Kit (Biomerieux SA, Marcy L’Etoile, France). Ninety-nine percent (247) of the isolates showed colony and cell morphologies typical of S. cerevisiae. Of these, 72 % (179) had fifty-three carbohydrate assimilation profiles similar to S. cerevisiae (according to Vaughan-Martini and Martini, 1998) and were subsequently identified as such while 28 % (68) which had four carbohydrate assimilation profiles atypical of S. cerevisiae or any other member of the sensu stricto complex could not be identified in API galleries. Two isolates (1%) which had colony and cell morphologies atypical of S. cerevisiae, and a broad-spectrum assimilation profile, were identified as Candida kefyr. Genotyping of five randomly selected isolates from each site was carried out using the Polymerase Chain Reaction (PCR) to amplify the region spanning the two intergenic transcribed spacers (ITS) and the 5.8S ribosomal gene (ITS1-5.8S rDNA-ITS2), followed by restriction analysis (ITS-PCR+RFLP) of the product, as well as Pulsed Field Gel Electrophoresis (PFGE). The genetic analyses indicated that all of them belonged to S. cerevisiae, notwithstanding the phenotypic differences. The mitochondrial cytochrome-c oxidase II gene (COX 2) of four isolates representing the four chromosome profile groupings that emerged after PFGE, were then sequenced to confirm their close relatedness to S. cerevisiae, particularly type strain CBS1171. Two isolates randomly selected from each of the ten production sites, (one with a broad carbohydrate assimilation spectrum and the other with a narrow carbohydrate assimilation spectrum) and assessed for technological properties showed different patterns of growth and flocculation without much change in pH during fermentation, and most of them produced pito having sensory attributes which compared favorably with commercially produced pito. Pito produced with each of ten out of the twenty yeast strains from Ghana used for the earlier investigations and three from Burkina Faso was analyzed by headspace, for its aroma constituents. All ten Ghanaian isolates could form aromatic compounds representing the alcohols, esters, and ketones which are among reported typical flavor compounds of conventional beer. This study has demonstrated diversity within S. cerevisiae strains involved in fermentation of pito wort. These strains possess desirable technological properties, including sufficient growth during fermentation and efficient hydrolysis of sugars for biomass enhancement. They also demonstrated fermentation activities, particularly, ethanol production, formation of aroma compounds and metabolites, which impart appropriate sensory attributes to pito.
Wastewater Irrigated Vegetable Production: Contamination pathway for health risk reduction in Accra, Kumasi and Tamale – Ghana.
(2008-10-21) Amoah, Philip
The study was conducted in three Ghanaian cities (Accra, Kumasi and Tamale) selected from different agro-ecological zones (Coastal Savanna for Accra, Moist Semi Deciduous Forest for Kumasi, and Guinea Savanna for Tamale) in two phases. The main methods used included surveys, crop and analysis, and field trials. In phase I, questionnaire interviews were used to gather background information from a total of 1058 subjects (farmers, sellers and consumers) from the three cities on wastewater use, distribution and handling of wastewater irrigated vegetables. In addition, direct observation and focus group discussions were carried out. Samples of waste water irrigated lettuce, cabbage and spring onions were also collected from selected markets in Accra, Kumasi and Tamale to determine the current level of exposure of the Ghanaian urban population to hazardous pesticide and faecal bacteria contamination through the consumption of fresh vegetables produced with wastewater. All three vegetables were analyzed for total coliform (TC) and faecal coliform (FC) as well as helminth egg populations an all three vegetables using standard methods. Lettuce samples were also analyzed for pesticide residue. In view of the qualitative nature of most of the results from phase I, scientific quantitative data was provided to complement qualitative results, identify intervention points and provide the baseline for assessing the effectiveness of interventions. The requisite quantitative scientific data and implications were covered in the second phase of the study. Lettuce was used as test crop because of the higher level of FC from markets (phase I) compared to cabbage and spring onions. Tamale was also dropped because farmers used similar irrigation water sources as in Accra. At this stage, the microbial and physiochemical quality of irrigation water from different urban sources was assessed. From two vegetable production sites each in Accra and Kumasi, lettuce samples irrigated with water from drain, stream, well and piped water were collected at designated points along the “farm to fork” pathway and analyzed for TC, FC, and helminth egg populations. Attempts were also made to isolate and characterize representative types of faecal coliforms present on farm samples collected during the pathway to study to assess the potential health risk to consumers. Methods used for washing vegetables before consumption at households and street food kitchens were surveyed and modifications to improve on their efficacies in removal of FC and helminth eggs carried out in the laboratory. Some of the agronomic practices employed by farmers who used wastewater for vegetable production could be sources of both microbiological and chemical contamination and potentially put farmers, sellers and consumers at risk. For example, 52 to 65% of farmers in Accra, Kumasi, and Tamale irrigated their crops on the day of harvesting, affirming the need to develop measures to minimize the risk associated with water use in vegetable production. Majority of the irrigated vegetable sellers in Accra, Kumasi and Tamale condemned the use of polluted surface water for growing vegetables but could not indicate which input poses the highest risk. All respondents interviewed washed their vegetable before consumption. This is an indication that the last stage before consumption could be one of the best entry points where health risks reduction strategies could be put in place. Market vegetables from all there cities carried FC and helminthes egg populations ranging between 4.0 x 10³ to 9.3 x 10(8) /g for FC and 1.1 to 2.7 for helminth and exceeded ICMSF recommended standards. A number of different types of helminth eggs, including that of Ascaris lumbricoides, Ancylostoma duodenale, Schistosoma heamatobium and Trichuris trichiura, were also identified on lettuce, cabbage, and spring onions from the markets. Most of pesticide residues on lettuce exceeded the maximum Residue Limit (MRL) for consumption. Faecal coliform and helminth egg productions in irrigation water from different sources exceeded WHO recommended standards for unrestricted irrigation. From all the irrigation water sources in both Kumasi and Accra, Ascaris lumbricoides was the most predominant species recorded; population density ranged between 2 to 4 eggs /l. however, heavy metal concentrations were mostly within limits of international standard. Despite poor sanitary conditions in markets, post-harvest handling, and distribution of lettuce did not significantly increase the farm-gat contamination levels. High FC levels exceeding common guidelines for food quality were also recorded on lettuce irrespective of the irrigation water source. The result also showed that apart from wastewater, contaminated soil and poultry manure also contribute to crop contamination. Identified bacterial isolates from lettuce from lettuce sampled from the farms belonged to 9 genera (Cedecea, Enterobacter, Erwina, Escherichia, Klebsiella, Kluyvera, Aeromonas, Chryseomonas and Seratia). Presumptive test for E. coli 0154:H7 was positive for about 13% of isolates from Accra and 20% from Kumasi. The food vendor/consumer surveys revealed that the large majority of the households and street kitchens used various methods to wash vegetables before consumption. Washing vegetables, irrespective of the method used reduced FC and helminth populations in lettuce, but at varying degrees. Attempts made to improve on selected existing washing methods showed that there was promise for vinegar (> 4 long reductions possible at increased concentration and contact time) but with high financial implications for poor households: and this could reduce its adoption potential. The WHO has set health protection level of 10 /6 DALY (Disability Adjusted Life Years) pppy, which is achievable by 6 – 7 log reduction. However, none of the methods tested achieved this level of reduction alone. The study concluded that wastewater irrigated vegetable production threatens public health from the perspective of microbiological and pesticide contaminations. The need to reduce the potential health risks resulting from FC and helminth contamination of wastewater irrigated vegetables needs a more holistic approach than a simple focus on polluted irrigation water sources. The adoption of multiple barrier approach, where complementary risk reduction strategies are applied at various entry points before the vegetables reach the kitchen, is likely to make more significant impact.
Malaria Transmission Dynamics and Pyrethroid Insecticide Resistance Status of Anopheles Gambiae Sensu Lato Gilles (Diptera: Culicidae) in two Districts of the Brong Ahafo Region, Ghana
(2009) Hayford, Daniel
Malaria results from infection with Plasmodium species transmitted mostly through the bite of female Anopheles species. The Brong Ahafo Region (BAR) of Ghana is endemic for malaria with endemicity greater than 75%. The Ghana National Malaria Control Programme (NMCP) has prioritised the use of pyrethroid-treated bednet and/or indoor residual spraying as a key strategy for combating malaria transmission. Control of malaria transmission using insecticide treated bed-nets and/or IRS impacts on both morbidity and mortality due to malaria. Evidence of insecticide resistance in malaria vectors in different areas necessitates surveillance studies to allow prompt detection of resistance should it arise and thus enable its management. Also, in preparation for the future IRS expansion programme planned by the NMCP, data on indices of malaria transmission would be required from several parts of Ghana, including the BAR. Hence, density, diversity, biting habits, feeding behaviour, parity rates, survival rates, sporozoite rates and entomological inoculation rates (EIRs) as well as pyrethroid insecticide resistance in the main malaria vector were investigated in some communities in two districts of the BAR. Mosquito larvae were collected using the dipping technique and reared to the adult stage and used for the insecticide susceptibility bioassays. Adult mosquitoes were also collected using human landing catches. The susceptibility bioassays were carried out using the standard WHO diagnostic bioassay kits. Bioassays were performed on non-blood fed female mosquitoes 2- to 4-day old. Knockdown rates were recorded after 5, 10, 15, 20, 30, 40, 50, 60, and 80 minutes. Mortality rates 24 hours post-exposure were also noted. Anopheles gambiae complex mosquitoes were analysed using the An. gambiae species specific PCR protocol. DNA from specimens identified as An. gambiae s.s. were subjected to PCR assays for the identification of the M and S molecular forms, and the detection of the leucine to phenylalanine knockdown resistance (kdr) gene mutation. Ovaries of wild-captured adult mosquito samples were dissected to examine the ovarian tracheations in order to determine parity, survival rates and life expectancy. The heads and thoraces of the parous mosquito samples were tested for the presence of circumsporozoite antigens of P. falciparum using enzyme-linked immunosorbent assay. A total of 15,384 Anopheles was collected, 13,088 in the rainy season and 2,296 in the dry season. Three Anopheles species were identified in both seasons: An. gambiae s.l. Gilles (98.80%), An. hancocki Edwards (1.20%) and An. coustani Laveran (0.03%). Anopheles gambiae s.s. was the only member of the An. gambiae s.l. found, consisting of both the M and S molecular forms but the S form was predominant (72.30%). No M/S hybrids were found. The susceptibility tests showed resistance to deltamethrin and permethrin. That is, mortality rates below 80% were observed ranging from 45% to 59% for the 0.05% deltamethrin bioassays conducted at Ahafo Kenyasi and Sunyani respectively. Mortality rates for the 0.75% permethrin bioassays ranged from 27% to 35% for the Ahafo Kenyasi and Sunyani samples respectively. Lastly, 46% mortality was observed for the Ahafo Kenyasi samples tested with 1.5% permethrin. The leucine to phenylalanine kdr gene mutation was detected in the two molecular forms but it was more frequent in the S form. That is, approximately 80.1% and 31.0% of the S and M molecular forms of the An. gambiae s.s. respectively, had the mutation. Anopheles gambiae s.s had its peak biting activity in the third and fourth quarters of the night in the rainy season but activity in the dry season peaked in the third quarter. In the rainy season, human-biting rates did not differ significantly between Sunyani, Ahafo Kenyasi and Hwidiem but the rates in these communities were significantly higher than in Chiraa (p = 0.034). In the dry season, however, there were no significant differences in HBR between the study sites (p = 0.898). Overall biting rates were higher in the rainy season (p < 0.001). Parity and survival rate did not differ significantly between sites but they were higher in the dry season. The sporozoite rate of both the An. hancocki and An. coustani was zero. There were no significant differences in P. falciparum sporozoite rates of An. gambiae between sites and seasons, however, EIRs were higher in the rainy season. The average inoculation rate was 2.864 infective bites per man per night (ib/m/n) in the rainy season, which gives an estimated 85.92 infective bites per man per month (ib/m/m). Comparative figures for the dry season were 0.468 ib/m/n and 14.07 ib/m/m. An overall average inoculation rate was 1.649 ib/m/n, which gives an estimated 49.48 ib/m/m. The results of this study suggest that the An. gambiae s.s. populations are resistant to the pyrethroid (deltamethrin and permethrin) insecticides tested. The implication of this is that malaria vector control measures in these communities using pyrethroid insecticides may be compromised due to the existence of insecticide resistance in the main malaria vector, An. gambiae s.s. The results of this study also suggest that the present study communities are areas of high malaria transmission intensity with transmission occurring all year round even though it is significantly higher in the rainy season.
The anti-termite properties and basic phytochemicals of eight local plants and the chemical characterisation of thevetia peruviana (pers) k. schum in Ghana
(2009) Tagbor, Trinity Ama
There is an increasing interest in the use natural products for termite control because of their environmental safety. Some local plant materials have been mentioned as potential alternatives to synthetic termiticides. The objective of this work was to determine the antitermitic efficacy of locally available plants such as; Thevetia peruviana (pers) K Shum Carapa procera DC, Jatropha curcus L ,Cassia nigricans Vahl, Cymbopogon ginganteus (Hachst) Chiov), Hyptis spicigera Lam., Vetiver zizaniodes Nash (vetiver grass) and Chromolaena odorata (L). Following the identification and collection of the experimental plants and termite samples, a series of field and laboratory experiments were conducted using parts of the plants to determine their antitermite efficacy. Antitermite efficacy was measured as their tolerance to termite damage, repellency and toxicity to termites. This was followed by extraction into petroleum ether, ethanol and water and the analysis of the most efficacious extract by chromatography (thin layer, column and high pressure) and spectrometry (mass spectrometry, nuclear magnetic resonance and infra red) methods to identify the active ingredients in the extract of the most efficacious plant. Resistance to termite destruction was measured by the loss in weight of stakes buried in treated and untreated soil and by visual assessment of extent of destruction. Repellency or attrantancy was determined by counting the number of termites that moved towards or away from filter paper pads treated with extracts of the test material. The results showed that soil treated with pulverised materials from T. peruviana offered the best protection to buried stakes against damage by subterranean termites. Field tests conducted with petroleum ether, ethanol and water extracts of T. peruviana suggested that the ethanol extract of T. peruviana resisted the destructive effects of termites most. In the repellency/attrantancy test, the ethanol extract was found to be an attractant. When the fractionated components of the ethanol extract were tested on brine shrimps, fraction 1 was found to be highly toxic suggesting obvious cytotoxicity. Analysis of fraction 1 by chromatography and spectrometry methods indicated the presence of two components digitoxin and digitoxigenin which were found to be toxic to brine shrimp. Sucrose was also isolated from the crude ethanolic extract of T. peruviana. Thus this work has shown that the potential for the use of anti-termite agents from T. peruviana is promising.
Quantum Mechanical Studies of the Mechanisms of Some Transition Metal Organometallic Reactions
(2009-07-18) Tia, Richard
The mechanistic pathways of three organometallic reactions, namely the oxidation of ethylene by chromyl chloride leading to the formation of epoxide, 1,2-dichloroethane, 1,2-chlorohydrin, acetaldehyde, and vinyl alcohol precursors; the olefin metathesis reaction involving ethylene and 20 metal methylidene Cl4MCH2(M=Cr, Mo, W, Ru, Re) and metal oxo-methylidene Cl2(O)MCH2(M=Cr, Mo, W, Ru, Re) complexes; and the transition-metal-assisted formation of 1,2-dinitroso complexes of cobalt and its congeners have been studied using hybrid density functional theory at the B3LYP/LACVP* level of theory. The formation of the epoxide precursor (Cl2(O)Cr-OC2H4) was found to take place via initial [2+2] addition of ethylene across the Cr=O bond of CrO2Cl2 to form a chromaoxetane intermediate, as opposed to [3+2] addition across the two Cr=O bonds of CrO2Cl2 as suggested in earlier studies. The hitherto unexplored pathway involving initial [3+2] addition of ethylene across the Cr=O and Cr-Cl bonds of CrO2Cl2 was found to be more favorable than the [3+2] addition across the two Cr-O bonds of CrO2Cl2. The formation of the 1,2-dichloroethane precursor was found to take place via [3+2] addition of ethylene across the two Cr-Cl bonds of CrO2Cl2. The 1,2-chlorohydrin precursor was also found to originate from [3+2] addition of ethylene across the Cr-O and Cr-Cl bonds of CrO2Cl2 as opposed to [2+2] addition of ethylene across the Cr-Cl bond. Also the vinyl alcohol and acetaldehyde precursors were found to arise from a direct attack of one of the carbon atoms of ethylene on an oxygen atom of CrO2Cl2 through a triplet intermediate. In the reactions of Cl4MCH2(M=Cr, Mo, W, Ru, Re) with ethylene it was found that the formation of the metallacyclobutane through formal [2+2] cycloaddition, a key step in the olefin metathesis reaction according to the Herrison-Chauvin mechanism, is a low-barrier process in each of the complexes studied. It was also found that the active species for the formation of the metallacyclobutane is a carbene complex and not a carbenoid complex. One key factor was found to be responsible for the difference in metathesis activity in these complexes: the stability of the carbenoid complexes relative to the carbenes. In Cr and Ru, the carbenoid complexes are more stable than the carbenes and thus Cl4CrCH2 and Cl4RuCH2 are likely to exist in the lower- 21 energy carbenoid Cl3MCH2Cl form as opposed to the carbene Cl4M=CH2 form. This is likely to deplete the reaction surface of the active species of the process, making Cl4MCH2(M=Cr, Ru) not suitable for olefin metathesis. This suggests that whereas Cl4MCH2 (M = Mo, W, Re) may catalyze olefin metathesis, Cl4MCH2 (M = Cr, Ru) may not. The W and Re complexes have been found to have greater metathesis activity than the Mo complex. In the Cl2(O)MCH2 (M=Mo, W, Re) complexes the metathesis reaction has favorable energetics and is found to be more feasible than the side-reactions studied while in the Cl2(O)MCH2(M=Cr, Ru) complexes, the olefin metathesis is found to be less favorable than the side reactions. In the transition-metal-assisted formation of 1,2-dinitrosoalkanes, it was found that the activation barriers for the one-step [3+2] addition pathway for the formation 1,2-dinitrosoalkanes are generally very low while the activation barriers for the [2+2] addition of the C=C bond of the olefins across the M-N bonds of CpM(NO)2 (M=Co, Rh, Ir) to form an intermediate are generally very high. A transition state for the re-arrangement of the products of [2+2] addition to the products of [3+2] addition could not be located, indicating that the re-arrangement of the products of [2+2] addition by reductive elimination involving the second metal-nitrogen π-bond to form the observed 1,2-dintrosoalkanes as suggested in the work of Rappé and Upton may not be possible. Therefore it is concluded that the direct one-step [3+2] addition pathway proposed by Bergman and Becker for the formation of 1,2-dinitrosoalkanes is a more plausible pathway.
Characterization of water yam (Dioscorea Alata) for existing and potential food products
(2009-08-05) Baah, Faustina Dufie
The yam species, Dioscorea alata has an advantage for sustainable cultivation due to its comparatively good agronomic characteristics. This research was aimed at identifying the major chemical and physical characteristics of D. alata tubers that affect food and industrial processing qualities. Tubers from 20 varieties of D. alata were compared to a reference variety, D. rotundata. The tubers were processed into flour for the determination of quality characteristics. Pounded yam, boiled yam and amala products were also prepared for sensory assessment against the reference. The influences of tuber maturity and length of storage on the quality characteristics were also evaluated, as well as the tuber tissue microstructure. On the average, most of the characteristics evaluated were relatively higher in D. alata varieties as compared to D. rotundata: moisture (72.2%), sugar (5.7%), protein (6.0%) and total dietary fibre (6.9%) contents; higher water binding capacity (163.3%), solubility (11.0%), and amylose (29.4%); breakdown (198.7 RVU), peak time (6.3 min) and pasting temperature (84.2 oC). However, dry matter (27.8%) and starch contents (68.4%), peak, setback, and final viscosities (215.7, 57.3 and 256.0 RVU respectively) were comparatively lower. D. alata varieties equally had appreciable contents of minerals. Based on the physicochemical and chemical properties, D. alata could be processed to flour for use in bakery products and diet formulations. The measured physicochemical properties in conjunction with pasting properties of the D. alata varieties suggest the presence of strong bonding forces within their starch granules. The relatively higher pasting temperatures required, and the lower pasting viscosities make D. alata suitable for producing weaning foods and other products that require low viscosity. Pasting properties of D. alata revealed relatively higher thermal and mechanical stability which will make it a good ingredient for processed foods, especially those that require thermal sterilization. The sensory analyses showed that D. alata varieties have comparative advantage over D. rotundata for amala production. However, specific promising varieties (TDa 98-159, TDa 291, TDa 297 and TDa 93-36) would need further genetic improvement to render them suitable for boiled yam and pounded yam dishes. Microstructural studies of the cooked cells in majority of the D. alata varieties (71%) showed incomplete disruption of the cells and consequently reducing exudation of starch contents. This feature partly accounts for less suitability of D. alata for sticky and doughy yam products in production areas. Moisture content of D. alata tubers decreased significantly from 5 to 9 months after planting (MAP) (74.53 to 71.76%) and throughout the 5 months storage period (71.76 to 68.06%) as a result of dehydration. Sugar and starch contents increased from the 5MAP to 9MAP (4.54 to 4.70%; 65.92% to 72.01% respectively), however, starch content decreased at the end of 5 months storage period (72.01 to 66.55%) with concomitant increase in sugar content (4.70-6.83%). The observations are due to photosynthetic materials accumulation during growth period and breakdown of starch to sugars as a result of respiration during storage. Amylose content generally decreased with the storage period but swelling power increased (6.26-9.02%). Pasting viscosities increased throughout the growth period to the end of storage. The increases in dry matter and sugar contents, swelling power and pasting viscosities of stored D. alata tubers would have significant improvement in their organoleptic and textural properties. Contribution to Science From this study, the following have been established and therefore add onto the scientific knowledge on D. alata yam species: 1. D. alata varieties had higher total dietary fibre than what is reported for brown rice (5%) (Best, 2005) with a few varieties having comparable values to whole wheat flour. The specific varieties with high TDF will be useful in diet formulation because of its health benefits 2. D. alata flour (elubo) is very good for amala product. This product should be promoted in Ghana due to the high flour storability and ease of preparation. 3. Significant mineral variations were observed among D. alata varieties which suggest the potential for improvement through breeding programmes.
Diversity in Anopheles gambiae s.s and Wuchereria bancrofti, and the Distribution of Lymphatic Filariasis in Ghana
(2010) Dziedzom, Komi de Souza
Lymphatic Filariasis (LF) is a disease transmitted by the filarial worm Wuchereria bancrofti. It is a disease of public health importance, and has been earmarked for elimination by the year 2020 through Mass Drug Administration (MDA) programs. In Ghana, the distribution of LF reveals a pattern of endemicity separated by a continuous area of non-endemicity. As such, this study hypothesized that genetic differences – probably not revealed by current identification methods, within LF vectors and parasite populations, may be responsible for the observed distribution pattern. The main aim of this project was therefore to explain the current observed distribution of LF based on the diversity in the Anopheles gambiae s.s and Wuchereria bancrofti in Ghana. Mosquito samples were collected from 14 sites across Ghana, divided into 4 ecological zones, and falling into endemic and non-endemic areas. W. bancrofti samples were picked from dissected mosquitoes -using dissecting pins, collected from previous studies in Ghana. The samples were morphologically and molecularly identified using routine methods. Using the PCR, the Cytochrome C Oxidase subunit 1 (COI) from W. bancrofti and An. gambiae s.s was amplified, sequenced and analyzed. To better understand the effects of environmental factors on the diversity in the An. gambiae s.s, the spatial distribution of the An. gambiae M and S molecular forms and associated environmental factors were examined, and their relationship with disease prevalence was determined. A total of 10274 mosquitoes were collected, out of which 6150 (59.9%) were morphologically identified as An. gambiae s.l; 1494 (24.3%) of the An. gambiae s.l were further classified into sibling species. The S form of An. gambiae s.s predominated in the middle belt, while the M form predominated in the northern and coastal Savannah belts. Bivariate correlation analysis between the M and S forms indicated that their prevalences were negatively correlated (-0.763). Spatial analyses carried out, indicated a positive spatial clustering for both the An. gambiae M (MI =0.19, Z score=4.2, P< 0.01) and An. gambiae S (MI =0.19, Z score=4.2, P< 0.01) forms. Multiple regression analyses of all data (n=70 sites), indicated that temperature was an important variable for both forms, explaining for An. gambiae M, 28% (R2=0.28, F=25.8, P<0.001) and for An. gambiae S, 36% (R2=0.36, F=37.9, P<0.001) of the variance in the model. An. gambiae M was significantly correlated with LF, and 2.5 to 3 times more prevalent in the high LF zone than low to medium LF zones. Phylogenetic analyses of An. gambiae s.s revealed the samples to be grouped according to endemicity and ecological zones. The equality of evolutionary rate between the consensus sequences from the endemic and non-endemic areas, revealed a χ2 test statistic of 3.71 (P = 0.054), rejecting the null hypothesis of equal rates between lineages. Seven and 15 W. bancrofti specimens from Gomoa District (in the South) and Bongo District (in the North) respectively were sequenced. There was a significant difference in the evolutionary rate between the consensus sequences of W. bancrofti from the North and the South, with a χ2 test statistic of 7.44 (P = 0.00637). The results of this study indicate that environmental factors, especially temperature, play an important role in the distribution of LF and its vectors in Ghana. The observed genetic differences in An. gambiae s.s and W. bancrofti populations in Ghana may affect the vector-parasite interactions in various areas, and may explain the observed distribution of LF in the country.
Impact Attenuation System Using a Passive Damper
(2010-03-18) Agyei-Agyemang, Anthony
The goal of this work is to mitigate the degree of damage to passengers caused by automobile collisions. Crash phenomena involving road vehicles were investigated for the purpose of developing an impact attenuation design that can withstand speeds higherthan the current specified range of up to 4 km/h (for a bumper). Different impact attenuation systems in the vehicle were studied with emphasis on the bumper modeling, analysis and design. A mathematical model for a bumper was developed. Simulation of impact of the bumper against a fixed barrier was performed. A passive friction element was introduced into the bumper system to improve on the attenuation of the impact and kinetic energy absorption capacity. A mathematical model of the bumper-damper system was formulated and used to simulate impact phenomena for a 1900 kg mass moving at a speed of 70 km/h (19.4 m/s), 17.5 times the speed of a typical design specification. The simulation revealed that the energy absorption capacity of the bumper was improved with the addition of a frictionelement. Design parameters for the friction damper were extracted from the results of the simulation. The extracted design parameters includestiffness, k, and coefficient of the damping, c, of the bumper. The use of the results from ii the simulation in the design of the bumper was pursued with success. Friction damper designs were proposed. Two of thesedesigns were built and used in experiments to verify their effectiveness and to validate the simulation results. The experiments revealed that higher energy absorption could be achieved with the addition of afriction element to traditional bumpers. From simulation, it was observed that a combinationof material stiffness and damping factors could influence energy absorption ability of the damper. It was observed that the addition of a friction element to an ordinary bumper-damper system with the new design parameters can improve its energy absorption capacity by 103.6 kJ,that is about 146 %. Additionally, it was also observed that the addition of the friction element to a traditional vehicle could increase the critical design speed from 4 km/h (1.11 m/s) to 14.9 km/h (4.1 m/s). It was concluded that a passive friction damper system could be used to attenuate road vehicle impact energy in collisions (of vehicles of mass similar to that of a typical sedan car) at speeds 3times higher than the speed for which current conventional bumpers are designed to attenuate (i.e. 4 km/h).
Spatio-temporal Variability of Phytoplankton Community Species Composition, Biomass and Primary Productivity of Lake Bosomtwe (Ghana)
(2010-07-12) Awortwi, Francis Emmanuel
In this thesis, the community composition, biomass and primary productivity of the phytoplankton of Lake Bosomtwe on spatio-temporal scales are presented for the first time in relation to the physico-chemical environment. Horizontal and temporal/seasonal variabilities in the wet weight biomass, chlorophyll a, gross productivities, and community respiration as well as growth rates are also assessed. Phytoplankton community composition and biomass were assessed from 14 different stations in spatial surveys and 1 index central station for temporal studies. Samples were collected biweekly (temporal study) and in stratified and mixing periods (spatial study) with a 6-Litre van Dorn sampler and preserved with acid Lugol. Samples were counted using inverted microscopy and converted to wet weight biomasses by approximating cell volume through routine measurements of 30-50 cells of an individual species and the application of the geometric formula best fitted to the shape of the cell. Identifications were performed on preserved whole and net (10 µm mesh) samples. The in situ light and dark bottle oxygen method was used for studying photosynthesis. An adapted version of the phytoplankton production model was employed to quantify phytoplankton photosynthesis and community respiration. Both chlorophyll a and total phosphorus were estimated. Coefficient of variance, t-test, ANOVA and the Levine test of homogeneity of variance were used to assess annual, inter-annual and seasonal variability of the means of physico-chemical and biological variables. Community species composition consisted of a total of 56 in horizontal and 75 in temporal studies in 7 major groups dominated by the Chlorophyceae. But the biomass dominated by the Cyanobacteria. Mean biomass of phytoplankton was 1570.0 in the first year (2004-2005) and 2262.3 mg m-3 in the second year (205-2006). Annual mean gross primary productivity of 4.73 gC m-2d-1 is high but net productivity was very low i.e. 0.38 gC m-2d-1. This was due to the very high community respiration that represented 90 % of the gross primary productivity and may imply higher loss rates. Mean growth rate in the Zeu of 0.13 d-1 is low and is commensurate with the low biomasses observed in the lake. Very weak relation between biomass and chlorophyll a and the little change in community composition in an annual cycle show that the changes in the chlorophyll a concentration are due to adaptation of the same community to differing conditions within the water column. Variabilities in the community biomass that range from a Coefficient of Variance of 28-79 % and that of the gross primary productivity of 33.1 % are high and seem to be regulated by the similarly high variabilities in the physico-chemical parameters. Significant inter-annual differences in the community biomass were observed. Physical factors such as Zmix and Zeu seem to exert more control in the dynamics of the phytoplankton growth and productivity compared to chemical factors even though nitrogen limitation is suggestive because of the abundance of heterocyst-bearing filamentous Cyanophyceae. Selective grazing may also be contributing to some extent to the observed dynamics.
Evaluation of the microbiological and physicochemical quality of borehole water in the Offinso District of Ashanti Region
(2010-08-11) Amankona, Benjamin Kwasi
The quality of borehole water from seven administrative town councils namely Asuoso (AS), Akenkaasu (AK), Samproso (SA), Abofour (AB), Offinso (OF), Afrancho (AF) and Bonsua (BO) in the Offinso District of Ashanti region were analysed from January 2007 to June 2007. Water samples were collected from thirty-five boreholes comprising five boreholes in each town council and analysed for temperature, pH, colour, turbidity, conductivity, total dissolved solids, alkalinity, hardness and some selected anions PO3-4, NO2-,SO2-4) some heavy metals (Cd, Cu, Zn, Mn and Pb), total and faecal coliforms. From the results, pH of the water was slightly acidic (5.03-6.53) and was unaffected by the seasonal variation. The water was moderately soft to slightly hard (12.8-226.80mg/l CaCO3). The nutrient loads observed in the water were slightly low and fell within the WHO standards. There were isolated cases of cadmium contamination at Asuoso (AS), Abofour (AB) and Bonsua (BO) recording 0.00198, 0.00124, 0.00158 and 0.00164, respectively. With the exception of pH, all the other parameters analysed were influenced by seasonal variations. There was a general increase in all the parameters during the wet season with turbidity, conductivity and total dissolved solids recording high values. The mean total coliforms ranged between 10 and 20CFU/100ml while all the samples analyzed recorded zero for faecal coliforms. The results suggest that borehole water sources in the Offinso district were of acceptable quality.
Biting Patterns of Mosquitoes, the dynamics of Malaria Transmission and Existence of the Knockdown Resistance (kdr) Gene in parts of the Central Forest Belt of Ghana
(2010-8-24) Abonuusum, Ayimbire
Malaria is presumed to be holoendemic in the forest belt of Ghana, through no comprehensive transmission studies have been conducted...
New Cone Metrics on the Sphere
(2011-06-13) Boadi, Richard Kena
We give an explicit construction of lattices in P U (1, 2). A family of these lattices was originally constructed by Livn´e [15]. Parker [19] constructed these lattices of Livn´e as the modular group of certain Euclidean cone metrics on the sphere. In this work we give a construction of these lattices which includes that of Parker’s as the modular group of certain Euclidean cone metrics on the sphere. Our cone metrics on the sphere had five cone points with cone angles (π − θ + 2φ, π + θ, π + θ, π + θ, 2π − 2θ − 2φ) Where θ > 0, φ > 0 and θ + φ < π. These corresponds to a group of five tuples lattices generated by Thurston [27] in his paper Shapes of Polyhedra and Triangulations of the Sphere . Hence our choice of θ and φ in order to obtain discreteness are as follows: θ 2π/3 2π/3 2π/3 2π/4 2π/4 (2π/5) 2π/5 2π/6 φ π/4 π/5 π/6 π/3 π/4 (2π/5) π/3 π/3 Certain automorphisms which we considered on our cone metrics yielded unitary matrices R1, R2 and I1. Using these matrices, we obtained our fundamental polyhe- dron D by constructing our vertices, edges and faces to define the polyhedron. Our vertices were obtained by the degeneration of certain cone metrics. The polyhedron D is contained in bisectors whose intersection give us the edges of the polyheron. The faces are also contained in the bisectors. Then finally we proved using Poincar´e’s polyhedron theorem that the group Γ generated by the side pairings of D is a dis- crete subgroup of P U (1, 2) with fundamental domain D and presentation: J 3 = Rp = Rp = (P −1J )k = I , \ 1 2 Γ = J, P, R1, R2 : R2 = P R1P −1 = J R1J −1, P = R1R2
Assessment of Public Exposure to Naturally Occurring Radioactive Materials from Mining and Mineral Processing Activities of Tarkwa Goldmine in Ghana
(2011-06-14) Faanu, Augustine
Mining has been identified as one of the potential sources of exposure to naturally occurring radioactive materials (NORM). However, mining companies are not being regulated for NORM in Ghana. Whilst the developed countries have identified NORM as potential problems and measures are being taken to address the issues, very little is being done in the developing countries. However, most of the NORM industries such as mining and mineral processing are located in developing countries such as Ghana. Currently, there are over two hundred (200) registered mining companies operating small, medium and large scale mining in Ghana. Tarkwa Goldmine is one of the largest gold mining companies in Ghana and has been in operation for the past 200 years with no data on radioactivity levels. The mine currently undertakes only surface mining and the process produces large volumes of tailings and waste that may contain NORM. Some of the NORM are soluble in water and have the tendency to leach into water bodies and farm lands. These studies have been carried out to determine the exposure of the public to NORM from processing of gold ore at the Tarkwa Goldmine in Ghana. Direct gamma spectrometry and neutron activation analysis (NAA) techniques were used to analyse for U/Th series and K-40 in soil, rock, water, food and particulate (dust) samples from the mining environment. The mean activity concentrations measured for 238U, 232Th and 40K in the soil/rock samples were 15.2 Bq/kg, 26.9 Bq/kg and 157.1 Bq/kg respectively. For the water samples the mean activity concentrations were 0.54 Bq/L, 0.41 Bq/L and 7.76 Bq/L for 226Ra, 232Th and 40K respectively. The mean activity concentrations of 226Ra, 232Th and 40K in the food samples were 0.18, 0.14 and 45.00 Bq/kg respectively. The mean activity concentrations measured in the dust samples were 4.90 and 2.75 µBq/m3 for 238U and 232Th respectively. The total annual effective dose to the public was estimated to be 0.74 mSv. The results in this study compared well with typical world average values. The results indicate an insignificant exposure of the public to technologically enhanced NORMS from the activities of the Goldmine. The radiological hazard due to226Ra, 232Th and 40K were carried out. The radium equivalent activity (Raeq) and the calculated external and internal hazard indices, the absorbed dose rates and the corresponding annual effective dose were estimated in the soil and rock materials that might possibly be used as building materials. The results obtained in this study shows insignificant radiological hazards for the materials considered for use as construction materials for dwellings by the inhabitants in the study area. The results obtained in this study also shows that the background radiation levels are within the natural limits and compared well with similar studies for other countries. The study assessed the concentration of U, Th and K as well as other trace metals, anions and the physical parameters in water and soil samples in the goldmine and its surrounding areas. The mean concentrations of the U, Th and K were 0.020, 0.029 and 1.19 mg/L. The concentration of U, Th and K were variable in soil and rock samples taken from different locations in the study area with mean values varying in a range of 0.2 to 1.8 µg/g, 0.9 to 2.6 µg/g and 7037 to 71360 µg/g respectively. The concentrations of U, Th and K are comparable to world average values of similar studies. The calculated Th/U ratios show that there has not been significant fractionation during weathering of the radioelements with a mean value of 2.5. The concentrations of the other trace metals, anions and the physical parameters are within the WHO guideline levels in drinking water. The mean values of the gross-α and gross-β activity concentrations were 0.012 and 0.137 Bq/L which are also below the WHO recommended guideline values for drinking water.
New cone metrics on the sphere
(2011-10-05) Boadi, Richard Kena

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