[en] Using direct measurement, we investigated entrance surface doses of patients for routine radiographs in attempt to develop evaluation methods of patient dose in order to establish the guidance level in Ghana. To date, patient doses have been evaluated by calculation based on radiographic conditions, or model experiments using phantoms, also based on several assumptions. Direct measurement of patient dose is difficult to perform in many patients due to its time requirement, level of expertise required and difficulty in providing an explanation of the procedure to the patient. However, such direct measurement is essential since it incorporates all aspects of radiography from the radiographic equipment used, to the actual conditions of each patient without assumption. In this study, we examined the need for introducing the guidance level, controversial points in the calculation method for patient dose evaluation, evaluation accuracy required for introducing the guidance level, and necessity for a standardized method. The variation between measured and calculated doses range between -4.8 to +29.3 per cent. Computational technique is a wide ranging and cost effective method od conducting representative patient dose estimations in plain radiography. (au)

[en] Two field experiments were conducted in 2012 at the plantation Crop section of the Department of Crop and Soil Sciences, Kwame Nkrumah University of Science and Technology, to investigate the effect N availability on nodulation, nitrogen fixation, N remobilization and grain yield of soybean. The design used in both studies was a 3 x 4 factorial arranged in randomized complete block design. Each treatment was replicated three times. The factors studied were rate and time of N fertilizer application. The N rate were 0, 20, 40 and 60kg N/ha and the time of application were early vegetative and early flowering phases. Anidaso, an improved soybean variety of 110 days maturity was used. Following land preparation, seeds were planted at the beginning of the rains at a spacing of 50 x 5cm. All required cultural practices were observed. Data collected were nodule number per plant and nodule dry weight, number of pods per plant, number of seeds per pod, 100 seeds weight, total nitrogen fixed, harvest index, grain yield and remobilized N. The total nitrogen difference method was used in determining the amount of N₂ fixed by the soybean and the micro kjeldahl method was used in determining the total plant N. The results indicated that nodulation was not significantly (p>0.05) affected by N rate and time of N application. However Nitrogen fixation was significantly (p<0.05 in affected time of N application in the minor season. Harvest index was significantly affected time of N application in the major season. Grain yield was also significantly affected by time of N application in both seasons. The results indicate that if farmers would apply N fertilizer to soybean at the vegetative growth phase, there would be increase in yield. The study also demonstrate that N remobilization occurs in soybean during grain filling although rate and time of application used did not significantly (p>0.05) affect N remobilization. (au)

[en] Repeated exposures of Shigella dysenteriae strain A to ultra-violet radiation (253.7 nm) with intervening outgrowth of survivors gave rise to clear bacteriophage plaques. Isolation, propagation and partial purification of the new Shd-4LI0 phages showed that they are similar in morphology to the Myxobacteriaphage Mx-4 described earlier. The new phages retained the general characteristics of S. dystenteriae phageShd-4L3, including serological properties and phage typing. It is suggested that ultra-violet irradiation may have played a role in the transformation and excision of the presumed lysogen of S. dysenteriaestrain A into a lytic phase. PhageShd-4LI0 was subsequently partially characterized. It has a density of 1.61, a DNA: protein ratio of 0.42 and thus a cryptogram of D/2:54.3/32.5:X/X: B/O. The phage was further characterised by fractionation of its protein using SDS-polyacrilamide gel electrophoresis. DNA extracted from phages was hydrolysed with restriction endonuclease R., EcoR1. The restriction fragments were catalogued and their apparent molecular weights calculated from electrophoresis gels calibrated with fragments from DNA of coliphageλ λ. From the total fragments obtained with nuclease R., EcoR1, the apparent minimum molecular weight of phage Shd-4LI0DNA was found to be 54.3 x 10⁶ Daltons. The molecular weight of the phage DNA was also calculated from measurements of contour length of purified DNA samples, using the formula MW = 1.97 x 10¹⁰ 1/(magnification), where 1 is the measured length of DNA in centimetres). The very close relatedness with phage Shd-4L3 was confirmed by these techniques. (au)

[en] Groundwater potential of the sedimentary formation in the Brong Ahafo Region of Ghana has been evaluated using computed transmissivity and specific capacity values. Data on multiple step and constant-discharge tests on twenty (20) boreholes were analyzed. The Cooper-Jacob's straight line analytical approach was used to determine the aquifer characteristics. Computed transmissivity coefficients of the underlying aquifer ranged widely from 0.82 - 61.27 m2d-1. The specific capacity values obtained varied between 0.59 and 75.20 m3d-1m-1. Total head loses of the boreholes ranged generally between 5.49 and 99.2%. Hydrogeologically, the aquifer systems can be described as fairly heterogeneous in accordance with Krasny's transmissivity classification model. Ground-water potential of the sedimentary aquifer system could be classified as high to intermediate to yield substantial groundwater resource for domestic and industrial water supply. To secure substantial quantity of water for sustainable water supply in areas underlain by this sedimentary aquifer system in Ghana, integrated geophysical approach including 2D-Continuous Vertical Electrical Resistivity (CVES) survey, and other related tools such as Remote Sensing (RS) and Geographical Information Systems (GIS) should be used to enhance the delineation of deeper aquifer zones of high groundwater potential. (au)

[en] Mixed farming systems are practiced in low latitude localities where the land tenure is inflexible and the soil is usually marginal. Two experiments were designed to evaluate Nitrogen (N) resource utilization in such systems as practiced in moist savanna and forest-savanna transitional agroecologies of West Africa. Two cowpea (Vigna unguiculata) and two maize (Zea mays) cultivars of peanut (Arachis hypogea) and Sorghum sp. were used in the other as monocropped and mixed cropped treatments. Plants were provided with fertilizer N treatment at the rates of 0, 5, 10 and 35 mg N kg ¹ of soil as ¹⁵ N-labeled ammonium sulphate. Legume components of inoculated treatments received a mixture of three serologically-distinct strains of Bradyrhizobium sp. recommended for each legume species. Results showed that mixed cropped legumes responded to Bradyrhizobium inoculation and utilized significantly (P<0.05) higher amounts of nitrogen from the atmosphere when compared with monocropped legumes. The inoculation response was influenced by legume-cereal combination, plant cultivars, and soil available nitrogen. The results indicate that in soils of given N availability status, selection of appropriate legume-cereal cultivar combinations will be a useful management practice for enhancing BNF for the benefit of resource poor farmers (author)

[en] Soil sediment samples collected from Tarkwa and its environs were investigated for the levels. of mercury, using atomic absorption spectrophotometric technique. It was observed that mercury levels were generally high in both soil and sediment. Mercury levels in soil at the catchment areas of Chifan River ranged from 30.71±5.913μgKg^-1 at C₃ (near Tarkwa-Takoradi main road) to 142.50±9.48μgKg^-1. The minimum level of mercury in soil samples at the catchment areas of Chifan River was about three times the accepted WHO 1993 level of 10μgKg^-l. Sediment samples recorded 458.53±14.52μgKg^-1 at C₃ (near Tarkwa-Takoradi main road). Mercury was not detected at C₄. The pH_w, of both soil and sediment samples were normal. Boboboo catchment area recorded the highest levels of mercury in sediment and soil samples. Soil samples from Bentinri showed 183.46±5.67μgKg,^-1 while Drobo showed 203.43±11.17μgKg^-1. Mercury levels in the study area were generally very high. (au)

[en] The Government of Ghana by Legislation Instrument L.I 1732 banned the production, importation, storage, sale and use of leaded gasoline in Ghana with effect from 1^st January 2004. The aim of this work is to find out the contribution of lead to the atmospheric aerosol two years after the coming into force of the ban. The sampling was done using a Gent sampler with stacked filter units and the aerosol collected size fractionated into PM_2.5 (fine) and PM_10-2.5 (Coarse). Energy dispersive x-ray fluorescence (EDXRF) analysis was used to identify and quantify lead (Pb) and other elements in both the coarse and fine fractions. The average concentration of Pb in the ambient air was 1.49 ngm^-3 and 0.70 ngm^-3 for the coarse and fine fractions respectively. The average total of both the coarse and fine fractions (which is PM₁₀) was 2.19 ngm^-3, which is well below the US EPA set standard of 1.5 μgm^-3. Source apportionment on the fine fraction using Principal Component Analysis (PCA) showed that mostly soil/dust and to a lesser extent combustion processes were the sources of the Pb. (au)

[en] The study assesses heavy metals contamination of some communities along the Jim River Basin in the Ashanti Region. The Jim River Basin is within the mining concession of Ashanti Goldfields Company (AGC) Limited, now Anglogold Ashanti. The selected communities receive drainage and effluent from mining, processing and waste containment facilities of AGC and from the activities of illegal small scale miners (galamseys) in the area. Representative samples of water from streams, boreholes, hand-dug wells, stream and over bank sediments, and fruits were analyzed for Mn, Cu, Zn, Ni, Pb and Cd using the Unicam 969 Atomic Absorption Spectrometer (AAS). Fe was determined by ion chromatography, As by an ARL 341 hydride-generator and Hg by cold vapour Atomic Fluorescence Spectrometry. Protracted periods of underground mining, recent extensive surface mining and intensified illegal mining activities were identified as major sources of augmented levels of heavy metals in water, sediment and fruit samples. Sediments and fruits exhibit higher concentration of determined metals than water. Cu, Cd, Zn, and Ni, are generally low in water samples, while Fe, As and Mn are generally high, particularly in stream water and ranged from < 0.002 to 17.100mg/l, 0.001 to 6.318mg/l and <0.001 to 2.584mg/l respectively. Metal concentrations were highest in sediments. Fe values in sediments ranged from 2210-50180 mg/kg and averaged 28270mg/kg, Hg between 0.26 to 3.02 mg/kg and averaged 1.21mg/kg while arsenic ranged between 0.24-to 7591.58mg/kg and averaged 1746.51mg/kg. Heavy metals in fruit samples were considered indicative of their bioavailability. Some fruits showed extremely high concentrations Hg, Zn and As. High heavy metal concentrations are generally coincident with areas of past and/ or of active mining and processing activities. (author)

[en] The effects of solar radiation on the photosynthetic oxygen production and pigmentation were investigated in the marine filamentous cyanobacterium. Microcoleus chthonoplastes harvested from the intertidal zone of the Biriwa coast in Ghana. The organism was exposed to unfiltered solar radiation (UV-B. UV-A and PAR) and solar radiation filtered through optical filters. WG320 (UV-A and PAR), GG400 (PAR only), and UG5 (only UV-B and UV-A), Photosynthetic oxygen production was impaired. The reduction in the rate of photosynthetic oxygen production took over 2 hours to occur. The photoinhibition due to unfiltered solar radiation and combined UV-A and PAR were most severe. Absorption spectra of the crude extracts of M. chthonoplastes, indicated the presence of chlorophyll a, carotenoids, phycoerythrin and phycocyanin as the photosynthetic pigments, which were significantly bleached under the various solar radiation wavelengths. Generally, the phycobilins were affected most. Fluorescence measurements showed peaks that decreased significantly in amplitude and also underwent a shift towards shorter wavelengths, with prolonged exposure time, indicating that energy transfer from the accessory pigments was adversely affected. The implication is that increased solar radiation may have severe consequences on the marine ecosystem. (au)

[en] Cadmium sulphide thin films have been prepared by the chemical bath deposition technique (ph 11, 70 degree centigrade). Two different sets of films were prepared under varied conditions and concentrations of their ions sources (Cd²⁺ from cadmium nitrate, S^2- from thiourea) and Na₂EDTA as a complexing agent. A UV mini-Schimazu UV-VIS Spectrophotometer was used to determine the optical absorbance of the films as a function of wavelength at room temperature over the wavelength range 200 - 600 nm. The samples were then thermally annealed for thirty minutes, at temperatures of 100 degree centigrade, and 200 degree centigrade, after which the absorbance of the films were again recorded. The band gap values obtained for the sample with 0.5 M CdS as deposited, annealed at 100 degree centigrade and 200 degree centigrade were 2.1 eV, 2.2 eV and 2.3 eV respectively. Whilst the values obtained for the sample 0.15 CdS as deposited, annealed at 100 degree centigrade and annealed at 200 degree centigrade were 2.0 eV, 2.01 eV and 2.02 eV respectively. The increase in band gap with annealing temperature might be attributed to the improvement in crystallinity in the films. (au)