Carbothermal Upgrading of the Awaso Bauxite Ore using Sawdust and Coconut Shells as Reductant

Ghana’s bauxite is exported in the raw state with no value addition. One way to achieve value addition is to carbothermally upgrade the ore into magnetic and nonmagnetic fractions, followed by separation using a magnet. This work investigates the carbothermal upgrading of the Awaso bauxite ore using reductant generated from locally available saw dust (SD) and coconut shells (CNS). Composite pellets of bauxite-reductant were prepared, air-dried and cured for 72 hours. The cured pellets were placed in a fire-clay crucible and heated in a custom-made gas-fired furnace for 30 minutes. The fired composite pellets were separated into magnetic and non-magnetic portions using a low intensity hand-held magnet. The various portions were then characterised using XRD, XRF and SEM analyses. XRD results showed magnetite as the predominant species present in the magnetic fraction whilst the non-magnetic fraction showed alumina as the predominant peaks along with some traces of unreduced hematite, silica, carbon and titania but no hercynite.  Keywords: Bauxite, Palm Nut Shells, Gas-Fired Furnace, Hercynite, Cha

INVESTIGATION OF HORIZONTAL AND VERTICAL CONTROLS ON KNUST CAMPUS

Controls are coordinated horizontal or vertical positional data for land and geographic information systems forming a framework to which surveys are started, referenced and adjusted. Controls on KNUST campus were established over three decades ago with new ones being added as and when t h e y a r e required. Conventional survey methods like trilateration, triangulation and traversing were used and are still being used for densification of controls. These approaches involve the use of low precision instruments such as analogue/optical theodolites and leveling equipment. Since the establishment of these controls, t h e y have not been investigated but t h e y are being used for p r o j e c t development. A modern method that uses satellite positioning techniques such as GPS is currently in operation and has numerous advantages in the establishmentof control networks. GPS control surveys were carried-out on seven controls and ellipsoidal coordinates were obtained in the World Geodetic System 84 reference frame. The Cartesian coordinates were projected onto the Universal Transverse Mercator frame. A two dimensional conformal transformation was done using existing KNUST boundary coordinatesto Ghana National coordinates based on the War Office ellipsoid. Precise Level routines were carried out on the seven controls for the computations of orthometric heights. The method of least squares adjustment, root mean square errors (RMSE), standard errors (SE) and residuals derived were used to analyse the differences in horizontal positions and heights of the controls.The linear displacement between the computed and the existing coordinates were within the range of 0.015m to 0.014m. The RMSE were 0.048 and 0.106, whiles the SE were also 0.057 and 0.125 for the northings and eastings respectively. The computed and existing heights differed between -0.075m and -0.004m with a mean downward movement of 0.011m.Keywords: Surveying; coordinates; control points; GPS; precise leve

The Role of Formal and Informal Institutions in Smallholder Agricultural Adaptation: The Case of Lawra and Nandom Districts, Ghana

As the current frequency of climate impacts is expected to increase in semi-arid regions of Ghana, smallholder farmers will require access to new and relevant information to adapt successfully. Institutional support is increasingly gaining attention for effective and successful adaptation; however, there is limited knowledge on the specific roles of both formal and informal organizations in implementing adaptation strategies in semi-arid regions. Using the Lawra and Nandom Districts as case studies, the various roles of existing institutions in adaptation strategies were examined. A total of 135 household questionnaires, six focus group discussions (FGDs), 20 in-depth interviews with farmers, and seven key informant interviews from institutions evaluated climate risks and impacts, adaptation responses of farmers and the functions of the different institutions in supporting these adaptation strategies. Majority of respondents observed that irregular and unpredictable rainfall (77%), high temperature and extreme heat (56%) and rainfall irregularities during growing season (55%) as the main changes in the past 10 years. Major agricultural adaptation strategies identified were changing of planting dates (100%), planting of different varieties of the same crop (51%), planting of trees (35%) and seasonal migration by the local farmers (21%). There is high dependence by the smallholder farmers on formal institutions’ resources to adapt, especially for developing/ building the local capacity, rather than on local innovations within the communities. This is mainly due to the lack of knowledge about climate change risks and adaptation strategies and limited or no access to financial resources. Government-led adaptation is considered to be more sustainable than NGO-led programmes although it comparatively lacks specific mandates and financial resources. Continued support by formal institutions will therefore enable the development of more effective agricultural adaptation initiatives

Precipitable Water Comparisons Over Ghana using PPP Techniques and Reanalysis Data

Atmospheric Water vapor is an important greenhouse gas and contributes greatly in maintaining the Earth’s energy balance. This critical meteorological parameter is not being sensed by any of the 22 synoptic weather stations in Ghana. This study presents a highly precise tool for water vapor sensing based on the concept Global Navigation Satellite Systems (GNSS) meteorology and tests the computed results against global reanalysis data. Conventional approaches used to sense the atmospheric water vapor or Precipitable Water (PW) such as radiosondes, hygrometers, microwave radiometers or sun photometers are expensive and have coverage and temporal limitations. Whereas GNSS meteorological concept offers an easier, inexpensive and all-weather technique to retrieve PW or Integrated Water Vapor (IWV) from zenith tropospheric delays (ZTD) over a reference station. This study employed precise point positioning (PPP) techniques to quantify the extend of delays on the signal due to the troposphere and stratosphere where atmospheric water vapor resides. Stringent processing criteria were set using an elevation cut-off of 5 degrees, precise orbital and clock products were used as well as nominal tropospheric corrections and mapping functions implemented. The delays which are originally slanted are mapped unto the zenith direction and integrated with surface meteorological parameters to retrieve PW or IWV. The gLAB software, Canadian Spatial Reference System (CSRS) and Automatic Precise Positioning Service (APPS) online PPP services were the approaches used to compute ZTD. PW values obtained were compared with Japanese Metro Agency Reanalysis (JRA), European Centre for Medium-Range Weather Forecasts Reanalysis (ERA-interim) and National Center for Environmental Prediction (NCEP) global reanalysis data. Correlation analysis were run on the logged station data using the three approaches and global reanalysis data. The obtained results show stronger correlation between the retrieved PW values and those provided by the ERA-interim. Finally, the study results indicate that with a more densified network of GNSS base stations the retrieved PW or IWV will greatly improve numerical weather predictions in Ghana.Keywords: GNSS Signals, PPP, Integrated Water vapour, Precipitable Water, Reanalysis Model

Impacts of climate change and climate variability on maize yield under rainfed conditions in the sub-humid zone of Ghana: A scenario analysis using APSIM

Climate change and variability pose a serious threat to food production in sub-Saharan Africa. The projected changes in local spatio-temporal patterns of rainfall and temperature will likely affect the availability of water and nutrients, crop growth, and yield formation. This paper presents the simulated effects of climate change on maize (Zea mays L.) in Ejura in the Sekyedumase district of Ghana, one of the important food baskets of the country. Experimental data from maize grown under various nitrogen (N) and phosphorus (P) conditions in the 2008 major and minor rainy seasons at two sites in Ejura were used to parameterize and evaluate the cropping systems model APSIM. Daily climatic data for the period 2030-2050 under the scenarios A1B and B1 were obtained from the regional climate projections obtained by the mesoscale model MM5. The assessment of climate change impact on grain yield suggested a likely 6-week shift in the planting dates of the rainy season from the current (1980-2000) 3rd week of March to the 2nd week of May for the simulated period. Climate change also resulted in projected yield reduction of, on average, 19% and 14% for the Obatanpa maize variety under A1B and B1, respectively, for maize-maize continuous cropping. Likewise, the Dorke maize yield is expected to reduce by 20% and 18% for A1B and B1, respectively, with increased yield variability under both scenarios. Potential adaptation measures to climate change in the area include cropping of cowpea during the minor season or fallow rotation with other crops

Groundwater Vulnerability Assessment using Drastic Index and GIS in Kumasi Metropolitan Assembly, Ghana

The assessment of groundwater vulnerability to contamination has become an important element for landuse planning and groundwater resource management. This study aims at estimating groundwater vulnerability using an integration of Geographic Information System (GIS) and DRASTIC method in the Kumasi Metropolitan Assembly (KMA). The groundwater vulnerability map was prepared using index and overlay analysis with the aid of Arc GIS 10. The DRASTIC Index (DI) computed ranged between 70 and 164 as the lowest and highest contamination potential respectively. The eastern and western flanks and north-west tip of KMA are underlain by the granites which bear water due to the combined effect of weathering and fracturing and are dominated by "Very High", "High" and "Moderate" vulnerability based on the vulnerability index computed. The "Low" and "Very Low" vulnerability are located at the northern, central and southern parts of KMA which are underlain by phyllites. These suggest that boreholes located in the Birimian metasedimentary units which comprise mainly phyllites would be less likely to be vulnerable to contamination than those located in the intrusive rocks dominated by the granites. Keywords: Groundwater Vulnerability, Soil Media, Hydraulic Conductivity, Overlay Analysi

Comparisons between sequenced and re-sequenced genomes of historical subterranean clover mottle virus isolates

We report comparisons between the complete genomic sequences of five historical Western Australian isolates of subterranean clover mottle virus (SCMoV) from 1989–2000, and an infectious clone of its 1989 isolate. Sanger Sequencing (SS) and High Throughput Sequencing (HTS), or both, were used to obtain these genomes. Four of the SCMoV isolates were sequenced by SS in 1999–2002, but re-sequenced again by HTS in 2020. The pairs of sequences obtained from these four isolates differed by only 18–59 nucleotides. This small difference resulted from the different sequencing methods, the < 1–5 years each isolate was host passaged before freeze-drying prior to HTS sequencing, or a combination of both. Since SCMoV has not been reported outside Australia, this similarity suggests the population sequenced represents the progeny of either an indigenous virus that spread from a native legume to subterranean clover after its introduction or a recent seed-borne incursion from elsewhere. The ORF1 was the most variable, and the phylogenetic tree constructed with ORF1s showed the isolates grouped according to their symptom severity in subterranean clover, indicating the probability that ORF1-encoded P1 protein is a symptom determinant. A satellite RNA was associated with all SCMoV genomes obtained by HTS but none derived by SS

Relative Response Factor for Lamivudine and Zidovudine Related substances by RP-HPLC with DAD detection

A study was conducted to establish the Relative Response Factors for Zidovudine related impurity C, Lamivudine salicylic acid and Zidovudine related impurity B.  A simple and fast isocratic Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method was used for the simultaneous determination of the related impurities. The method consists of a mobile phase combination of Acetonitrile (HPLC grade) and Buffer (0.0680 g of Potassium Dihydrogen Orthophosphate, 0.3 ml of Triethylamine, pH adjusted to 8.0 with Orthophosphoric acid to a final volume preparation of 100 ml) in the ratio 10:90 using Phenomenex Luna 5-µm C18 (2)-250 x 4.6-mm, 5-µm) as a stationary phase, flow rate of 1.0 mL/min with detection at 270 nm. The RRF for Zidovudine related impurity C, Lamivudine salicylic acid and Zidovudine related impurity B were 2.07, 0.13 and 1.28 respectively.   Results obtained for quantification of the related substance in lamivudine and zidovudine single dose oral solid dosage form using the RRF and know standards shows no significant difference at 95 % confidence interval. The RRF can therefore be used for the quantification of know related impurities in lamivudine zidovudine oral dosage form using the stated chromatographic conditions