Browsing by Title
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Gobagoba, L.; Meyer, T.; Ringrose, S.; Kampunzu, A.B.; Coetzee, S. (Botswana Society, NaN, 2005)[more][less]
Abstract: Calcrete deposits of the Qangwa area, northwestern Botswana are evaluated on the basis of satellite imagery and sedimentological analysis. Enhanced Thematic Mapper imagery interpretation combined with field evidence has led to identification of the calcrete. This project aims at making a detailed surficial geology map accompanied by a report as a step in expanding the knowledge of calcretes. It also attempts to develop an understanding of the relationship in the timing of the late Quaternary wetter and drier phases. A digital map using GIS and remote sensing applications was developed from both analysed data and fieldwork. Data analysis revealed five types of calcretes and a calcareous soil. Hardpan calcrete along with brecciated and conglomeratic calcrete dominate the interfluves and are believed to predate the formation of nodular and honeycomb calcrete which occupy the valleys. The older hardpan associated types may have developed following regional wet/warm periods the last of which has been dated elsewhere as occurring c. 120,000. The younger valley calcretes show different mechanisms of formation, and are believed to have been developed following incision and palaeo-lake establishment, c. 25,000 years ago. URI: http://hdl.handle.net/10311/943 Files in this item: 1
Gobagoba 2005 calcrete mapping.pdf (2.409Mb) -
Mpuchane, S.; Allotey, J.; Matsheka, I.; Simpanya, M.; Coetzee, S.; Jordaan, A.; Mrema, N.; Gashe, B.A. (ICIPE - African Insect Science for Food and Health, http://journals.cambridge.org/action/displayJournal?jid=JTI, NaN, 2006)[more][less]
Abstract: Domestic cockroaches Blattella germanica were trapped from various homes in Gaborone, Botswana using ‘Dyroach’ traps. Isolations of bacteria, yeasts and moulds were done on external body parts and on the faecal pellets using various selective media. Body parts of cockroaches were also fixed with OsO4 vapour for 24 h, sputter coated with gold under special conditions and examined in a Phillips (1) XL30 ESEM in low vacuum mode. Awide spectrum of bacteria including common food spoilage and pathogenic organisms, such as Bacillus spp., Staphylococcus spp., Escherichia coli, Pseudomonas spp., Enterobacter spp., Klebsiella spp., Erwinia spp. Salmonella sp., Shigella sp. and Serratia spp. were isolated. Yeasts commonly associated with food spoilage, such as Pichia sp., Candida sp. and Torulopsis spp. were found on many cockroaches. In addition, various groups of moulds, some associated with food spoilage and others known to produce mycotoxins, such as Aspergillus flavus, Aspergillus fumigatus and Aspergillus parasiticus were isolated. Antimicrobial sensitivities of bacterial isolates revealed resistance patterns to various agents. Since cockroaches are prevalent in homes, particularly in food preparation areas and since their body parts and faecal pellets have been found in food storage areas, concern about their impact on food quality and safety is raised and possible control measures including education of communities on proper sanitation are suggested. URI: http://hdl.handle.net/10311/1005 Files in this item: 1
Matsheka_IJTIS_2006.pdf (193.3Kb) -
Rekha, A.; Raju, V.C.C. (University of Botswana, NaN, 1999)[more][less]
Abstract: The stress-attention in cascade reliability has been studied when both stess and strength follow Rayleigh distribution. The expression for the relaibility R(n), for a system survive with the first (n-1) components failed and the n component active, is obtained R(n) is calculated numerically, for n=1,2,3 and 4, for different values of the parameter p and the attention factor k. It has been found that with lower attention factors in high degree of reliability can be attained. URI: http://hdl.handle.net/10311/677 Files in this item: 1
Rekha_BJT_1999.pdf (887.1Kb) -
Mbaiwa, J.E. (Elsevier, www.elsevier.com, NaN, 2004)[more][less]
Abstract: This paper reviews available literature concerning water resources use in the Okavango River Basin (ORB). It describes a number of common arguments regarding possibilities for the emergence of violent conflict in and among Basin states, particularly those states party to the Okavango River Basin Commission (Okacom)—Angola, Botswana and Namibia. The paper presents data concerning present and future water demands and examines a number of formal, institutional steps taken by global and regional actors to facilitate sustainable development, natural resources management and peaceful cooperation in the Basin. Contrary to trends in much of the literature, the paper suggests that there is great scope for enhanced inter-state cooperation in the Basin. It argues that to achieve sustainable utilisation of water resources and avoid violent conflict in the ORB, an integrated management plan for the entire basin needs to be developed. In addition, each basin member-state should observe international and regional conventions and treaties governing the use of water resources when designing national water development projects that require the use of water from the ORB. URI: http://hdl.handle.net/10311/934 Files in this item: 1
Mbaiwa Causes and Solutions.pdf (1.775Mb) -
Pansiri, L.; Pansiri, N.O. (University of Botswana; http://www.ub.bw, NaN, 2011)[more][less]
Abstract: Poor parental involvement in schools and educational activities at basic education level is a concern the world over. Governments have promulgated deliberate educational policies to institute parental involvement through structures commonly known as Parents and Teachers Associations (PTA). Despite this structural approach, many countries including Botswana, experience poor parental involvement in a school located in a low-income township area in Gaborone – Botswana. The study confirms that there is lack of effective parental involvement in that school. One of the major challenges is that school activities and meetings are often held when the majority of the parents are at work. It therefore, recommended that PTA activities be held at a time that suits specific activities and tasks; and that teachers must be encouraged to visit their children’s homes to dialogue with parents on educational issues in order to inspire parents to participate in the education of their children. URI: http://hdl.handle.net/10311/1139 Files in this item: 1
Pansiri_PBJAS_2011.pdf (3.788Mb) -
Abegaz, B.M.; Ngadjui, B.T.; Dongo, E.; Ngameni, B.; Nindi, M.N.; Bezabih, M. (Elsevier Science Ltd. www.elsevier.com/locate/phytochem, NaN, 2002)[more][less]
Abstract: The twigs of Dorstenia prorepens furnished the digeranylated chalcone, 5,30-(3,7-dimethyl-2,6-octadienyl)-3,4, 20,40-tetrahydroxychalcone while Dorstenia zenkeri yielded the 30,40-(3-hydroxy-2,2-dimethyldihydropyrano)-4,20-dihydroxychalcone and a bichalcone. 4-Hydroxylonchocarpin was found in both plants. D. prorepens also yielded the known compounds: psoralen, bergapten, b-sitosterol and its D-glucopyranosyl derivative. D. zenkeri yielded p-hydroxybenzaldehyde, dorsmanin A, 4,20,40-trihydroxychalcone and 4,20,40-trihydroxy-30-prenylchalcone. Structures of the new compounds were established by UV, IR, MS and 2-D NMR analysis. URI: http://hdl.handle.net/10311/254 Files in this item: 2
Chalcones and other constituents.pdf (3.760Mb)license.txt (1.998Kb) -
Temtime, Z.T.; Mmereki, R.N. (Emerald Group Publishing Limited, www.emeraldinsight.com, NaN, 2011)[more][less]
Abstract: Purpose – The purpose of this paper is to examine the degree of satisfaction and perceived relevance of the Graduate Business Education (GBE) programme at the University of Botswana. Design/methodology/approach – A self-administered questionnaire and face to face interviews were used to collect data from Master of Business Administration (MBA) participants on their reason for studying MBA, level of satisfaction, and the extent to which the skills and experiences obtained correlate with those required by the corporate world. The data were analyzed using simple descriptive statistics. Findings – The majority of the respondents are male adults attending part time MBA classes and working full time in administrative positions in the public and private sectors. The study found that improved managerial skills, career development and broader business insights are major reasons for joining the MBA programme, while employability and economic gains were ranked low as driving forces. Even though the overall satisfaction with the programme is mixed and inconclusive, the MBA programme has assisted participants to develop basic management and administration skills. However, the programme puts greater emphasis on conceptual, technical and analytical skills than on problem solving, innovation, communication and entrepreneurial skills which are perceived to be most needed by employers, implying a relevance gap. What the MBA participants learnt does not correlate with what they perceived to be most needed by employers. Research limitations/implications – Since the findings are based on perceptions of MBA participants, the conclusions drawn from these findings must be considered tentative and interpreted with care. Future research must include representative sample of all MBA stakeholders such as faculty, students, graduates, employers and administrators to get rich information about quality of inputs, processes and products of MBA programme. Practical implications – There is strong need for the MBA programme to integrate traditional management and administrative skills with experiences and skills relevant for today's world of work. Bridging the growing theory-practice gap requires attracting professors with practical business experience, revising staff recruitment policies and procedures, establishing formal partnership with external organization, and develop long-term strategies to reduce teaching load and staff turnover. Originality/value – Most of the studies on the relevance and quality of GBE programmes are conducted in western higher education institutions, very little has been done in African universities. This is the first of its kind in the context of Botswana, an important contribution to existing literature and foundation for further advanced studies in the area. URI: http://hdl.handle.net/10311/860 Files in this item: 1
Temtime_QAE19_2011.pdf (1.911Mb) -
Adeyemi, M. B. (Caddo Gap Press, http://www.caddogap.com, NaN, 2009)[more][less]
Abstract: The world is a diverse ecosystem where humans and the environment must interact and live in harmony. In order to keep any society going, either at the national or global level, the importance of having visions for the improvement of that society cannot be overemphasized. It is in the light of this dream of making Botswana an enviable nation that the "Vision 2016" was published in 1997. A pillar of the "Vision" focuses on the development of a moral and tolerant nation. This article presents a brief literature review that focuses on the "moral and tolerant" aspects as aspirations of a nation. These two concepts are values which have implications for classroom pedagogy. This article reports an investigation of 64 teachers at the junior secondary school level and the challenges faced by them when teaching topics related to these values with their attendant remedies. The identified challenges included the difficulty of the use of critical and ethical reasoning methods in classes, a lack of community support, inadequate teachers' qualifications and experience, needed teaching resources, and the heterogeneity of the students, among others. The teachers provide some remedies to these challenges, while the investigator advocates for further research on the appropriate methods for teaching values in schools. URI: http://hdl.handle.net/10311/1098 Files in this item: 1
Adeyemi_ME_2009.pdf (655.4Kb) -
Makgala, C.J.; Botlhale, E. (Routledge (Taylor and francis), www.routledge.com, NaN, 2008)[more][less]
Abstract: This account of tribal finances in Bechuanaland Protectorate under British colonial rule argues that while the treasury dispensation made the tribes responsible for their finances, it also brought about a new dynamic and challenge in tribal communities as a result of a new monetary and financial system. Little or inadequate remuneration led to low morale, theft, and the employment of incompetent personnel in some instances. The colonial authority needed the chiefs to run tribal affairs and for political stability. As a result, chiefs often escaped unpunished whenever they were involved in peculation of funds. On the other hand, when tribal revenue workers did the same they were harshly dealt with. Efficiency and corruption in the treasury system differed from one area to another and was dependent on the character of the chief in the area. URI: http://hdl.handle.net/10311/924 Files in this item: 1
Makgala_AHR_2008.pdf (2.701Mb) -
Swatuk, L.A.; Kgomotso, P.K. (Elsevier, www.elsevier.com/locate/pce, NaN, 2007)[more][less]
Abstract: Supplying adequate water and sanitation facilities to small, scattered rural communities and/or large, fast growing settlements in remote areas is a challenge not easily met anywhere in the world. This article focuses on just such a challenge in the remote, rural area of Ngamiland District in north-western Botswana. Drawing on a combination of critical analysis of government and secondary data, participant observation, and key stakeholder interviews conducted over the period 2004–2006, the article shows that despite a good aggregate record of supplying water and sanitation throughout the country, there are abiding, often serious, problems with supply in remote areas. The research reveals that due to a combination of limited human and financial resource capacity, government policy that deliberately under-serves remote areas in order to encourage resettlement, and complacence among key decision-takers, supply problems go unresolved. The article suggests four key interventions as possible ways forward: using the Okavango Delta Management Plan (ODMP) process as a guiding framework for institutional reform; linking research directly to human resource capacity development; treating water as both a social and an economic good; and soliciting an IWRM ‘champion’ to drive the political process. URI: http://hdl.handle.net/10311/501 Files in this item: 1
Swatuk2007WATERSUPPLY.pdf (1.584Mb) -
Kalusopa, T. (Emerald, NaN, 2005)[more][less]
Abstract: Purpose – This paper attempts to discuss some of the key challenges that Zambia faces in the application of information communication technologies (ICTs) for the small-scale farmers. Design/methodology/ approach, A survey of information needs of small-scale farmers in two selected provinces was carried out in order to establish and prioritize their information needs. Evaluation of the existing information infrastructure provided insights into the type of ICTs that can support the provision of information to small-scale farmers in Zambia. Findings - The paper highlights some of the salient findings of the research carried out under the African Technology Policy Studies (ATPS), Zambian Chapter and financed by the International Development Research Foundation (IDRC) from 2001 to 2003. These, among others, include: weak human capital and technical infrastructure, lack of clear national information policy and lack of a coordinated agricultural information support system for small-scale farmers anchored on ICTs. Research limitations/implications – This study illustrates that it is becoming increasingly evident that the success of any agricultural development programme in Zambia requires a well organized and functionally integrated information delivery system propelled by the application of appropriate ICTs. The paper presents recommendations for this to be realized. Originality/value – The changes in the socio-economic and political arena in Zambia have had a drastic effect on the management of the agriculture sector. Further, even though it is widely acknowledged that information plays an important role in agricultural and rural development in Zambia, this conception has received less pragmatic attention and seems to have been less consolidated over time. The central role of information in this sector has thus been largely superficial. The need for a clear national policy framework on the use of ICTs for the small-scale farmers to enhance national development is thus articulated in this paper. URI: http://hdl.handle.net/10311/764 Files in this item: 1
Kalusopa_LHT_2005.pdf (897.5Kb) -
Mbaiwa, J.E. (Elsevier, September 5, 2010)[more][less]
Abstract: The Community-Based Natural Resource Management (CBNRM) program in Botswana aims at achieving conservation and rural development. In the Okavango Delta, some communities are involved in tourism through CBNRM to improve their livelihoods. However, research has not adequately analyzed changes caused by CBNRM on traditional livelihood activities and lifestyles. This study, therefore, uses modernization theory to analyze changes on traditional livelihood activities and lifestyles caused by CBNRM at Sankoyo, Mababe and Khwai villages in the Okavango Delta. Using primary and secondary data sources, results indicate that CBNRM is causing a decline in traditional livelihood activities like subsistence hunting, gathering, crop and livestock farming. As a result, a modern cash economy has emerged. New livelihood activities done by communities include: employment in CBNRM projects, the sale of crafts to tourists and thatching grass to tourism lodges. Income derived from CBNRM affords households to build modern houses, buy foreign foods and household equipment like: four-burner gas stoves, kitchen utensils, and satellite televisions. Conversely, this causes a decline in the consumption of traditional foods and the use of huts and household utensils. CBNRM is thus a modernization tool since it is causing a transformation of traditional livelihood activities and lifestyles. However, even though changes in livelihood activities and lifestyles may be an indication of the dynamism of culture in study villages, sudden change and modernization may increase livelihood insecurity. As such, tourism planning should ensure that modernization is sensitive to traditional economic systems and the need for rural livelihood sustainability. URI: http://hdl.handle.net/10311/805 Files in this item: 1
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Kalabamu, F. (Elsevier http://www. doi:10.1016/j.habitatint.2003.09.005, NaN, 2005)[more][less]
Abstract: The purpose of this essay is to identify gender contracts in self-help housing construction. Gender contracts have been defined as invisible power relationships that determine roles, responsibilities, privileges, status, sexuality and behaviour of men and women within households, communities, the market and the state. Gender contracts shape social, economic, political and sexual relationships in what people often refer to as ‘our culture’. Various gender contracts constitute a gender system (e.g. patriarchy or matriarchy) under which general rules, perceptions, hierarchies and privileges are formulated, refined and preserved. The paper notes that although the advent of colonialism and capitalism did not replace patriarchal structures in Botswana, they set in new political and production systems that upset the traditional power base and provided opportunities for women to challenge traditional gender contracts—notably the marriage contract that had hitherto been used to oppress women. The paper further notes that despite women having made inroads into male domains, there has surfaced new sites and forms of female subordination largely due to gendered inequalities in accessing and controlling contemporary critical resources (land, money, modern technical skills and formal employment) as well as continued male dominance of community and state structures. Taking Lobatse as a case study, the paper tries to identify gender contracts formed as a result of men’s takeover of construction activities which were traditionally undertaken by women in Botswana. It notes that besides dominating construction work, men control access to land, building skills, housing finance, and the entire self-help housing process in Lobatse, thereby forcing women into subordinate positions from which they have to bargain or negotiate new gender contracts. URI: http://hdl.handle.net/10311/430 Files in this item: 1
Kalabamu_HI_2005.pdf (2.325Mb) -
Mafela, L. (Routledge. http://www.informaworld.com, August NaN, 2009)[more][less]
Abstract: This study explores the historical relationship between the languages of Basarwa of Botswana and Setswana, in order to understand the dynamics underpinning their appropriation of the Setswana language, as they adjust to their changing livelihoods. The study contributes towards the promotion of a better understanding and awareness of the issues of language shift and language use amongst Basarwa. Basarwa occupy the lowest rungs of the social ladder in Botswana. Due to the close association between the status of the people and the status of their language, the Basarwa languages accordingly rank low in use and status nationally (Andersson & Janson, 2004, p. 118; Batibo, 2005, p. 71). Like the other minority languages, the Basarwa languages also have a low status and a low prestige in education and in written discourse. Moreover, the study observes that in their quest to mediate their socio-economic marginalisation, Basarwa have had to appropriate Setswana, the dominant national language for survival. However, their appropriation of the Setswana Language has had deleterious effects on their languages and overall sociocultural identity. In this context, the nationally dominant Setswana language not only dominates public discourse, but also official spoken discourse as well, while English dominates official written discourse (Andersson&Janson, 1993, pp. 83 84). The sources used to guide this analysis include secondary material, official and unofficial documents, as well as the author’s own observations, as a Motswana and an educationist. URI: http://hdl.handle.net/10311/529 Files in this item: 1
Mafela_IJM_2009.pdf (1.665Mb) -
Rankokwane, B.; Gwebu, T.D. (Springer, www.springerlink.com/index/52P6472307264K5M.pdf, NaN, 2006)[more][less]
Abstract: In Gaborone, as in other large cities in the developing world, individuals try to make a living by engaging in novel occupations such as landfill scavenging. This paper reports on a research conducted in the Gaborone landfill, the largest in Botswana. The study content-analyzed available literature from other countries. It also relied mainly on direct field observations. The discussions on and answers to closed and interview schedules by stakeholders, affected- and- interested – persons, provided the information on the threats and opportunities related to the landfill site and its informal management activities. This on-going case study lends credence to the potential of scavenging in sustaining livelihoods among those who cannot secure employment in the formal urban market. Scavenging tends to be useful although it may hazardous to the informal entrepreneurs. Taking all the threats into consideration, the decommissioning and closure of the landfill seems inevitable, in spite of the apparent short-term livelihood opportunities it provides to the informal sector. URI: http://hdl.handle.net/10311/362 Files in this item: 1
Rankokwane_GJ_2006.pdf (1.200Mb) -
Mabaleha, M.B.; Yeboah, S.O. (AOCS Press., NaN, 2004)[more][less]
Abstract: Seed oils from six legume cultivars of Phaseolus vulgaris, grown in the Kingdom of Lesotho, were extracted and their physicochemical properties and FA compositions were determined in order to compare their dietary lipids with those in P. vulgaris cultivars grown in other parts of the world. The oil content of the beans was very low, ranging from 1.5 to 2.0% (w/w). The acid values ranged from 11.0 to 19.2 mg KOH/g, whereas a combination of the PV and the p-anisidine values in Holm’s equation gave oxidation values that ranged from 11.0 to 15.0. Thus, considerable enzymatic hydrolysis and oxidation had taken place in the beans during storage. Iodine values ranged from 80.5 to 92.3 (Wijs method), indicating moderate unsaturation in the oils. However, capillary GC analysis, supported by proton NMR analysis of the FAME, gave a total unsaturation range from 79.67 to 84.24%. The dominant FA were α-linolenic acid (36.47–48.81%) and linoleic acid (20.96–36.10%), with appreciable amounts of palmitic acid (14.33–18.23%). This FA composition pattern is quite similar to the FA distribution reported for low oil-bearing legume seeds. Thus, notwithstanding the different climatic and soil conditions, the general properties of lipids in the southern African legume cultivars were quite similar to those of lipids in P. vulgaris cultivars grown in other parts of the world. The high content of α-linolenic acid in the cultivars of P. vulgaris could very likely play a beneficial role in reducing the risk of coronary heart disease among the large populations consuming them in the southern African region. URI: http://hdl.handle.net/10311/303 Files in this item: 1
Characterization and compositional.pdf (3.533Mb) -
Kayombo, B.; Meulenburg, F.; Moganane, B. G.; Dikinya, O.; Aliwa, J. N.; Nsinamwa, M.; Gaboutloeloe, G.; Patrick, C.; Mzuku, M.; Machacha, S. (University of Botswana, http://www.ub.bw, April NaN, 2005)[more][less]
Abstract: A study was carried out during 1998-2001 with the objective of, firstly, assessing the impact of cultivation on soil quality, and secondly, evaluating the effects of human and animal activities on soil erosion and range resources. A Topical Rapid Rural Appraisal (TRRA) based on rapid appraisal approaches, was conducted in three benchmark villages in Bobirwa Sub-district. A diagonistic survey report provided similar information for Kgalagadi District. Three benchmark sites were located in Bobirwa Sub-district and two others in Kgalagadi District. Soils were characterized at benchmark sites and in the laboratory for physiochemical properties. Soil erosion was monitored using embedded nail technique. At all benchmark sites, trends show a deterioration of soil quality, both in terms of nutrient depletion and poor physical properties for cultivated soils in comparison to uncultivated soils. There is visible evidence of environmental degradation of land resources resulting partly from considerable soil trampling and loosening during the dry season by livestock. During the wet season, the loosened soil is washed down elsewhere and/or deposited at watering points. The confounding effects of drought, overgrazing, poor management and ever-increasing utilization of veld products have led to the decline of a considerable number of tree and grass species. URI: http://hdl.handle.net/10311/645 Files in this item: 1
Kayombo_BJT_2005.pdf (3.655Mb) -
Characterization of arsenic occurrence in the water and sediments of the Okavango Delta, NW BotswanaHuntsman-Mapila, P.; Mapila, T.; Letshwenyo, M.; Wolski, P.; Hemond, C. (Elsevier Science B.V. Amsterdam; http://www.elsevier.com/wps/find/journaldescription.cws_home/768/description#description, NaN, 2006)[more][less]
Abstract: Detailed chemical analyses were performed on surface water, groundwater and sediment samples collected from the Okavango Delta between February and November 2003 in order to examine the distribution and geochemistry of naturally occurring As in the area. Surface water in the Okavango Delta, which is neutral to slightly acidic and has high dissolved organic C (DOC), was found to be slightly enriched in As when compared to a global value for stream water. Of the 20 new borehole analyses from this project, six were found to have values exceeding 10 ug/L. the current World Health Organization provisional guideline value for As. The results from field speciation indicate that As(III) is slightly more predominant than As(V). There is a positive correlation between As and pH and between As and DOC in the groundwater samples. For the sediment samples, there is a positive correlation between As and Co. As and Fe. As and loss on ignition (LOI) and between As and the percent fines in the sample. Reductive dissolution of oxides and hydroxides in the sediments with organic C as an electron acceptor is the likely mechanism for the release of As from the sediments into the groundwater. URI: http://hdl.handle.net/10311/135 Files in this item: 2
huntsman-mapila_app_geochem.pdf (3.170Mb)license.txt (1.998Kb) -
Døssinga, L.N.; Frei, R.; Stendal, H.; Mapeo, R.B.M. (Elsevier www.elsevier.com/locate/precamres, NaN, 2009)[more][less]
Abstract: Major and trace element, samarium (Sm)–neodymium (Nd) and lead (Pb) isotopic analyses of individual mesobands of five Banded Iron Formations (BIFs) and associated volcanic and sedimentary rocks from the Neoarchean Tati Greenstone Belt (TGB, Northeastern Botswana) were conducted in order to characterize the source(s) and depositional environment(s). Rare earth element (REE)–yttrium (Y) patterns of individual BIF mesobands showfeatures characteristic of other Archean BIFs with LREE depletion relative to MREE and HREE, positive La/La∗PAAS, Eu/Eu∗PAAS, Y/Ho ratios and no Ce/Ce∗PAAS anomalies. The REY patterns are comparable to modern seawater and together with low concentrations of high-field strength elements these features are indicative of an essentially detritus-free precipitation. Elevated Eu anomalies in the TGB BIFs are a general feature observed in ∼2.7 Ga BIFs worldwide and possibly result from widespread magmatic activity and associated high-temperature fluid fluxes to the oceans at around this time. Uranogenic Pb isotope data for the BIFs define correlation lines with slopes corresponding to apparent ages of ∼2.7 Ga which brackets the depositional timeframe. Pb isotope data on sulfides and Pb-stepwise leaching (PbSL) data on garnets define a correlation line with an apparent age of 1976±88 Ma. This age is similar to tectono-metamorphic events within the adjacent Limpopo belt. Elevated 207Pb/204Pb relative to 206Pb/204Pb ratios of BIFs are indicative of a high- (238U/204Pb) prehistory of their source materials which can best be modeled by a 3.0–3.2 Ga extraction of these sources from an older Archean mantle reservoir. The TGB BIFs show evidence of two periodically interacting water masses during the deposition. The first is characterized by elevated Sm/Nd ratios and a negative inferred εNd(2.7 Ga) value of −2.5 and is associated with high Fe fluxes. The second source, associated with high Si fluxes, is characterized by lower Sm/Nd ratios and a less negative inferred εNd(2.7 Ga) value of −0.4. While the association of high Fe concentrations and elevated Sm–Nd in BIF mesobands is characteristic of hydrothermal seawater input, the Sm–Nd isotopic characterization of this source, unlike other Archean BIFs, points to a significantly LREE enriched mantle source. This finding is compatible with the potential existence of a sub-continental lithospheric mantle reservoir beneath the Zimbabwe and Kaapvaal craton. The old (up to ∼3.5 Ga) Nd (TDM) model ages, particularly of iron-rich mesobands of the TGB BIFs, support such a scenario. In contrast, Si-rich solutes were likely derived from weathering of mafic continental crust. URI: http://hdl.handle.net/10311/389 Files in this item: 1
Mapeo2009Characterization.pdf (2.630Mb) -
Metuno, R.; Ngandeu, F.; Tchinda, A.T.; Ngameni, B.; Kapche, G.D.W.F.; Djemgou, P.C.; Ngadjui, B.T.; Bezabih, M.; Abegaz, B.M. (Elsevier Ltd. www.elsevier.com/locate/biochemsyseco, NaN, 2007)[more][less]
Abstract: Three species of the genus Treculia namely, Treculia acuminata Baill., Treculia africana Decne ex. Treà ´cul and Treculia obovoidea N.E.Br. grow in the humid rain forest of southwest Cameroon. They are also widely distributed in tropical Africa. T. africana is commonly known as African bread fruit. These three species are commonly used in folk medicine against skin diseases and dental allergies (Berg et al., 1985). The twigs, stem and wood of T. acuminata and the leaves of T. africana, whose chemical constituents are reported herein, were collected from Kumba, Cameroon, in August 2004, and identified by Mr Victor Nana of the National Herbarium in Yaounde, Cameroon where voucher specimens (N 2921/Srf/CAM and 29053/SRF/Cam, respectively) are deposited. URI: http://hdl.handle.net/10311/291 Files in this item: 1
Chemical constituents of Treculia.pdf (2.209Mb)