Browsing Faculty of Science by Title
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Gatsinzi, J-B.; Kwashira, R. (Nova Science Publishers, Inc.; www.novapublishers.com; reprinted with permission from Nova Science Publishers, Inc., NaN, 2007)[more][less]
Abstract: Let X be a finite product of even dimensional spheres, we show that the string homology of X contains a finite product of copies of the Witt Lie algebra. URI: http://hdl.handle.net/10311/162 Files in this item: 1
gatsinzi-kwashira1.pdf (139.6Kb) -
Prakash, J.; Ogulu, A. (Elsevier; www.elsevier.com/locate/ichmt, July NaN, 2007)[more][less]
Abstract: A mathematical model for the pulsatile blood flow in a small vessel in a cardiovascular system with a mild stenosis is analyzed. Blood is modeled as a power low fluid and the differential approximation for the heat flux is invoked in the energy equation. The effect of heat transfer on the velocity is computed and discussed. URI: http://hdl.handle.net/10311/226 Files in this item: 2
license.txt (1.998Kb)Prakash_ICHMT_2007.pdf (772.9Kb) -
Obuseng, V.; Nareetsile, F.; Kwaambwa, H.M. (Elsevier Science Ltd, www.elsevier.com/locate/aca, NaN, 2012)[more][less]
Abstract: Uptake for lead, copper, cadmium, nickel and manganese from aqueous solution using the Moringa oleifera seeds biomass (MOSB) and amine-based ligand (ABL) was investigated. Experiments on two synthetic multi-solute systems revealed that MOSB performed well in the biosorption and followed the decreasing orders Pb(II)>Cu(II)>Cd(II)>Ni(II)>Mn(II) and Zn(II)>Cu(II)>Ni(II). The general trend of the heavy metal ions uptake by the amine-based ligand followed decreased in the order Mn>Cd >Cu> Ni>Pb, which is the reverse trend for what was observed for MOSB. Comparing the single- and multi-metal solutions, there was no clear effect in the biosorption capacity of MOSB suggesting the presence of sufficient active binding sites for all metal ions studied. The MOSB performance is also not affected by pH in the range 3.5–8. URI: http://hdl.handle.net/10311/1039 Files in this item: 1
Obuseng_ACA_2012.pdf (886.0Kb) -
Lerouge, C.; Cailteux, J.; Kampunzu, A.B.; Milesi, J.P.; Fle´hoc, C. (Elsevier www.elsevier.com/locate/jafrearsci, NaN, 2005)[more][less]
Abstract: Luiswishi is a Congo-type Neoproterozoic sediment-hosted stratiform Cu–Co ore deposit of the Central Africa Copperbelt, located northwest of Lubumbashi (DRC). The ores form two main Cu–Co orebodies hosted by the Mines Subgroup, one in the lower part of the Kamoto Formation and the other at the base of the Dolomitic Shales Formation. Sulphides occur essentially as early parallel layers of chalcopyrite and carrolite, and secondarily as late stockwork sulphides cross-cutting the bedding and the early sulphide generation. Both types of stratiform and stockwork chalcopyrite and carrolite were systematically analyzed for sulphur isotopes, along the lithostratigraphic succession of the Mine Series. The quite similar d34S values of stratiform sulphides and late stockwork sulphides suggest an in situ recrystallization or a slight remobilization of stockwork sulphides without attainment of isotopic equilibrium between different sulphide phases (chalcopyrite and carrolite). The distribution of d34S values ( 14.4& to +17.5&) combined with the lithology indicates a strong stratigraphic control of the sulphur isotope signature, supporting bacterial sulphate reduction during early diagenesis of the host sediments, in a shallow marine to lacustrine environment. Petrological features combined with sulphur isotopic data of sulphides at Luiswishi and previous results on nodules of anhydrite in the Mine Series indicate a dominant seawater/lacustrine origin for sulphates, precluding a possible hydrothermal participation. The high positive d34S values of sulphides in the lower orebody at Luiswishi, hosted in massive chloritic–dolomitic siltite (known as Grey R.A.T.), fine-grained stratified dolostone (D.Strat.) and silicified-stromatolitic dolomites alternating with chloritic–dolomitic silty beds (R.S.F.), suggest that they were probably deposited during a period of regression in a basin cut off from seawater. The variations of d34S values (i.e. the decrease of d34S values from the Kamoto Formation to the overlying Dolomitic Shales and then the slight increase from S.D.2d to S.D.3a and S.D.3b members) are in perfect agreement with the inferred lithological and transgressive–regressive evolution of the ore-hosting sedimentary rocks [Cailteux, J., 1994. Lithostratigraphy of the Neoproterozoic Shaba-type (Zaire) Roan Supergroup and metallogenesis of associated stratiform mineralization. In: Kampunzu A.B., Lubala, R.T. (Eds.), Neoproterozoic Belts of Zambia, Zaire and Namibia. Journal of African Earth Sciences 19, 279–301]. URI: http://hdl.handle.net/10311/390 Files in this item: 1
Kampunzu2005SulpherIsotope.pdf (1.156Mb) -
Koosimile, A.T. (Elsevier, www.elsevier.com/locate/ijedudev, NaN, 2005)[more][less]
Abstract: This paper focuses on teachers’ experiences with implementing a modified International General Certificate of Secondary Education (IGCSE) physics syllabus in Botswana. The syllabus, characterised by a new organisational and pedagogic paradigm, is a significant shift from the traditional ‘‘teacher-proof’’ syllabus to one that is flexible, nonprescriptive and student-centred. Through data from discussions and interviews with teachers, it emerged that policy statements on the nature of the syllabus were contradictory and confusing to guide both the adoption and implementation of the syllabus. It also emerged that teachers accorded the core curriculum component of the syllabus a lower priority and status than the extended curriculum component. The findings also reveal that considerable overlaps in the core and extended curriculum components of the syllabus blurred the distinction between the two as well as weakening prospect of fidelity of adoption and implementation. The resulting ‘innovation gap’ invariably means that the ideals of the syllabus and the associated paradigm shifts are possibly not realised in teaching in Botswana. The findings generally underscore the importance of clear guidance and policy statements on any new syllabus, and indeed, a new curriculum. Possible directions in future research would be to investigate innovation gaps that might be manifest in teaching. URI: http://hdl.handle.net/10311/499 Files in this item: 1
Koosimile2005ICGSEphysics.pdf (1.142Mb) -
Masale, M. (Elsevier Science Ltd. www.elsevier.com/locate/physb, February NaN, 2002)[more][less]
Abstract: The experimental techniques of attenuated total reflection and grating-coupling were originally employed separately as probes for surface polaritons. However, as far back as the mid-1970s, some value was found in actually combining them into a single tool for probing elementary surface excitations. In this article, the theory of the two methods combined into one probe for surface polaritons is presented. The main results of the calculations, here, are the firstorder diffuse reflectivities, which arise due to the presence of a classical grating. For the ease of presentation, only a semi-infinite specimen is considered and the grating is thought to be deposited only on one interface. The discussion highlights the advantages the combined technique has over either of the two methods when each is employed on its own. URI: http://hdl.handle.net/10311/195 Files in this item: 2
license.txt (1.998Kb) -
Masale, M. (Elsevier Science Ltd. http://www.elsevier.com/wps/find/journaldescription.cws_home/505712/description#description, NaN, 2003)[more][less]
Abstract: The experimental techniques of attenuated total reflection (ATR) and grating coupling were originally employed separately as probes for polaritons. The combined technique of these methods into a single probe is a very versatile tool for probing elementary surface excitations. A theoretical investigation of this single probe for surface polaritons, ATRgrating coupling, is undertaken. The emphasis is on the calculations of first-order diffuse reflectivities, which arise due to the presence of a classical grating. More specifically, the ATR set-up in the Otto configuration is considered and for ease of presentation of the results, a classical grating is thought to be deposited on only one interface of a surface-active thin-film specimen. The discussion highlights the advantages the combined technique has over either of the two methods when each is employed on its own. URI: http://hdl.handle.net/10311/233 Files in this item: 2
license.txt (1.998Kb) -
Kumar, P.; Thangaraj, R.; Sathiaraj, T.S. (Springer Netherlands, NaN, 2008)[more][less]
Abstract: The melt-quenched Sn10Sb20Se70 sample in the bulk form was used to prepare films on well-cleaned glass substrates by thermal evaporation method. The activation energy for glass transition (apparent) and crystallization has been analyzed by using the Kissinger formulation. The X-ray diffraction study shows the crystallization of Sb2Se3 phase in the major proportion as compared to the SnSe2 phase. The SEM images film of the show the appearance of spherical globules upon annealing below the glass transition temperature. The effect of annealing temperature on the electrical and optical properties has been studied. A linear fit between DE and Eo is observed, indicating the validity of Meyer–Neldel rule with the change in the annealing temperature. Description: some mathematical symbols may not come as they are in the title and abstract. URI: http://hdl.handle.net/10311/691 Files in this item: 1
Thermal analysis.pdf (949.2Kb) -
Thermal annealing dependence of some physical propertiesof Bi-substituted Sn–Sb–Se glassy thin filmsAhmad, M.; Thangaraj, R.; Sathiaraj, T.S. (EDP Sciences, NaN, 2009)[more][less]
Abstract: Bulk glasses of the Sn10Sb20−xBixSe70 (0 x 8) system were prepared by the conventional melt quenching technique. Thin films were prepared by the thermal evaporation technique on glass substrates. Appearance of some crystalline phases is observed from the X-ray diffractograms after heat treatment below the glass transition temperature for 1 h. Scanning electron microscopy studies also show the presence of microcrystalline phases in the amorphous matrix after annealing for 1 h. The effect of Bi concentration and heat treatment on the optical gap and activation energy for dark conductivity were also investigated for the pristine as well as annealed films. The results are discussed on the basis of models related to the presence of defect states in chalcogenide materials. URI: http://hdl.handle.net/10311/534 Files in this item: 1
Thermal annealing dependence.pdf (822.7Kb) -
Mmopelwa, G.; Kgathi, D.L.; Molefhe, L. (Elsevier http://www.linkinghub.elsevier.com/retrieve/pii/S0261517706001440, NaN, 2007)[more][less]
Abstract: Moremi game reserve (MGR) in northern Botswana is one of southern Africa’s most popular destination because of its impressive wildlife and wilderness areas. To maintain the wilderness nature of the park and game reserve, the Government has pursued a policy of high cost-low volume which is not necessarily based on demand and supply characteristics of the tourist market. The present study determines the perceptions of self-drive tourists and clients of mobile tour operators on the prevailing park fees in MGR and uses the contingent valuation method to determine their willingness to pay (WTP) for park fees under a management scenario in which the management of the game reserve would be improved by a hypothetical international conservation organization. Data collection involved a self-fill of a questionnaire by these tourists in the game reserve. In the first scenario the mean entrance and camping suggested by nonresidents was higher than the prevailing fee. Residents suggested a lower entrance fee. In the hypothetical scenario, the mean maximum WTP for entrance and camping fee for South African and overseas tourists were higher than in the first scenario. There was a significant difference in the WTP for entrance fee between overseas tourists and South African tourists (p<0.05). Overall expenditure was significantly related to the WTP for increased park fees. The paper concludes by suggesting improvement in the MGR’s facilities for better satisfaction of tourists. URI: http://hdl.handle.net/10311/481 Files in this item: 1
Mmopelwa_TM_2007.pdf (1.545Mb) -
Gwebu, T.D. (Blackwell Publishing Ltd, http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1467-9663, NaN, 2006)[more][less]
Abstract: This paper investigates the extent to which the differential urbanisation model is applicable to Botswana by using empirical data obtained from periodic censuses, supportive documentary information and observations from personal on-going research on urbanisation and migration. Differential urbanisation refers to the cyclic spatio-temporal growth trends that the elements of human settlement hierarchies undergo, in response to migration. Empirical studies have verified the validity of differential urbanisation in the United States, Europe, India and South Africa. These areas, unlike Botswana, have longer histories of urbanisation, larger population sizes, denser population distributions, and higher levels of economic development. Current research interest is focused on investigating the theoretical applicability of the differential urbanisation model to those countries at the lower end of the economic development spectrum. The rationale and thrust of this paper is to therefore investigate the relevance of differential urbanisation under unique environmental, demographic and socio-economic conditions that pertain to Botswana. Evidence from the paper shows that urbanisation in Botswana has occurred in sequenced phases that, in general, resemble those suggested by the differential urbanisation model in the following ways. First, there has been concentration in the primate city due to mainstream migration. Secondly, there has been fission leading to the fast growth of the adjacent intermediate settlements, partly as a result of deglomeration economies at the primate core accompanied by substream migration. Third, the peripheral regional and rural centres appear to be now growing relatively rapidly, in response to the implementation of decentralisation policies. URI: http://hdl.handle.net/10311/956 Files in this item: 1
Gwebu_TESG_2006.pdf (1.050Mb) -
Mapolelo, M.; Torto, N. (Elsevier; www.elsevier.com/locate/talanta, NaN, 2004)[more][less]
Abstract: [Please note that chemical formulae do not display correctly in this abstract]. Sorption properties of baker's yeast cells, characterised as Saccharomyces cerevisiae were evaluated for trace enrichment of metal ions: Cd2+, Cr3+, Cr6+, Cu2+, Pb2+ and Zn2+ from aqueous environments. Metal concentration was determined by flame atomic absorption spectrometry (FAAS). Parameters affecting metal uptake such as solution pH, incubation time, amount of yeast biomass and effect of glucose concentration (energy source) were optimised. Further studies were carried out to evaluate the effects on metal uptake after treating yeast with glucose as well as with an organic solvent. The results showed that trace enrichment of the metals under study with yeast, depends upon the amount of yeast biomass, pH and incubation time. Treatment of yeast cells with 10-20mM glucose concentration enhanced metal uptake with exception to Cr6+, whose metal enrichment capacity decreased at glucose concentration of 60 mM. Of the investigated organic solvents THF and DMSO showed the highest and lowest capacity, respectively, to enhance metal uptake by yeast cells. Trace enrichment of metal ions from stream water, dam water, treated wastewater from a sewage plant and wastewater from an electroplating plant achieved enrichment factors (EF) varying from 1 to 98, without pre-treatment of the sample. pH adjustment further enhanced the EF for all samples. The results from these studies demonstrate that yeast is a viable trace metal enrichment media that can be used freely suspended in solution to achieve very high EF in aquatic environments. URI: http://hdl.handle.net/10311/156 Files in this item: 2
license.txt (1.998Kb)mapolelotortonew.pdf (469.7Kb) -
Phuthego, T.C.; Chanda, R. (Elsevier http://www.linkinghub.elsevier.com/retrieve/pii/S014362280300033X, NaN, 2004)[more][less]
Abstract: The advent of community-based natural resource management (CBNRM) in Botswana in the late 1980s ushered in a new paradigm in natural resource management. The strategy marked a change from state-controlled to community-controlled wildlife management. The expectation is that under community control, local expertise on biodiversity, termed in this paper as traditional ecological knowledge (TEK), plays a significant role that is supposedly facilitated through local institutions and traditional practices. This paper examines the incorporation of TEK in the CBNRM projects in KD 1, which is a controlled-hunting area (CHA) in the north-western part of the Kgalagadi North sub-district, Botswana and illustrates that the projects acknowledge and demonstrate the utility value of TEK in sustainable natural resource management. It concludes that TEK systems and institutions could serve as entry points into sustainable natural resource utilisation and management. This could be achieved through the exploration of cultural practices of the local people and integrating useful aspects into the modern natural resource management expertise. URI: http://hdl.handle.net/10311/418 Files in this item: 1
Phuthego_AG_2004.pdf (1.867Mb) -
Ngamba, D.; Awouafack, M.; Tane, P.; Bezabih, M.; Abegaz, B. (Elsevier Ltd. www.elsevier.com/locate/biochemsyseco, NaN, 2007)[more][less]
Abstract: Gladiolus psittascinus HOOK, an herbaceous plant, is propagated by its bulb. This onion-looking plant occurs in rocky places in western province of Cameroon. The bulbs are used to treat asthma, gonorrhoea, diabetes and intestinal parasites (Adjanohoun et al., 1990). The bulbs of G. psittascinus were collected in Dschang (West Province of Cameroon) in July 2005 and identified by Mr Francois Nana, a botanist at the National Herbarium, Yaounde where a voucher specimen (55925 HCN) is deposited. We report here the isolation and structural elucidation from the chloroform extract of two new anthraquinones namely: 1,6,7-trihydroxy-3-methoxy-8-methyl-anthraquinone (1) and 1-hydroxy-3,6,7-trimethoxy-8-methyl-anthraquinone (2) along with four known compounds. The structures of the compounds were elucidated by spectroscopic analysis, mainly, 1D and 2D NMR and by comparing their physical (mp) and spectroscopic (Table 1) data with those reported in the literature. URI: http://hdl.handle.net/10311/248 Files in this item: 4
license.txt (1.998Kb)license.txt (1.998Kb)license.txt (1.998Kb) -
Mazimba, O.; Majinda, R.R.; Modibedi, C.; Masesane, I.B.; Cencicˇ, A.; Chingwaru, W. (Elsevier Science Ltd, http://www.elsevier.com/locate/bmc, NaN, 2011)[more][less]
Abstract: The investigation of Tylosema esculentum (Morama) husks, cotyledons, and tuber yielded griffonilide 2, compound 1, griffonin 3, gallic acid 4, protocatechuic acid 5, b-sitosterol 6, behenic acid 7, oleic acid 8, sucrose 9, 2-O-ethyl-a-D-glucopyranoside 10, kaempferol 11 and kaempferol-3-O-b-D-glucopyranoside 12. The structures of the isolates were determined by NMR, HR-TOF EIMS, IR and UV–vis spectroscopy, and by comparison with literature data. The husk EtOAc and n-butanol extracts demonstrated >90% DPPH radical scavenging activity at concentrations of 25, 50 and 250 lg/mL. Furthermore the husk extracts showed higher total phenolic content (233 mg GAE/g). The extractives exhibited minimum inhibitory quantities of 50–100 lg or no activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Candida albicans. The tuber extracts were inactive against Caco-2 and Hela cell lines, while the husk extracts showed low activity against Caco-2 and Vero cell line with IC50 values >400 lg/mL. The GC–MS analysis showed the beans and tuber non-polar (n-hexane) extracts major constituents as fatty acids. URI: http://hdl.handle.net/10311/1029 Files in this item: 1
Mazimba_BMC_2011.pdf (698.8Kb) -
Masale, M. (Elsevier Science Ltd. www.elsevier.com/locate/physc, January NaN, 2003)[more][less]
Abstract: The problem of a type II superconducting disk in a spatially inhomogeneous magnetic field is considered. The aim of the investigations undertaken here is to evaluate the effects of the spatial inhomogeneity of the parallel component of the applied magnetic field on the nature of the superconducting nucleation of a short cylinder. Full numerical solutions of the linearized Ginzburg-Landau equation for the order parameter, taking into account only the parallel component of the field, are presented in the case of a solid disk;free-standing and in a metallic matrix. In the case of a mesoscopic system, only the limiting form of the critical temperature is obtained. The temperature-field (e-f) curves are characterized by flux-entry points at each of which the azimuthal quantum number decreases by unity. The quasi-period of the flux-entry points increases in f with the increasing strength of the spatial inhomogeneity of the applied field. The increased effect of coating the superconductor with a suitable normal metal leads to the well known suppression of the critical temperature as well as smoothing out of flux entries. It is predicted that the wiping out of surface nucleation is effected with relative ease when the applied magnetic field is uniform than when it posseses a degree of spatial inhomogeneity. URI: http://hdl.handle.net/10311/197 Files in this item: 2
license.txt (1.998Kb) -
Otiti, T.; Ekosse, G-I.; Stephen, S.T. (Bioline International. http://www.ajol.info/journal_index.php?jid=90, June NaN, 2007)[more][less]
Abstract: Normal, helical and zigzag deposited Ni films were produced by letting a vapour stream of source material impinge on Corning 1737 glass substrates at oblique incidence while rotating the substrate during deposition. Films produced by glancing angle deposition (GLAD) technique while rotating the substrate. The microstructures of these Ni films were studied using X-ray diffractometry technique. The X-ray diffraction (XRD) patterns depicted 100% and 42% relative intensity (RI) peaks identified for normal and helical deposited Ni films but none for the zigzag deposited Ni film. Higher degree of crystallinity of Ni was demonstrated by the helical thin film sample having 200 nm thickness (sample Ni40) compared to the normal thin film which had only the 100% RI peak defined. Should an application therefore require Ni thin films of high crystallinity, it would be the film prepared with helical microstructure of 200 nm thickness that will be employed. URI: http://hdl.handle.net/10311/353 Files in this item: 2
license.txt (1.998Kb)Otiti_JASEM11_2007.pdf (451.5Kb) -
Mazimba, O.; Majinda, R.R.; Masesane, I.B. (Elsevier Science Ltd, http://www.elsevier.com/locate/tetlet, NaN, 2009)[more][less]
Abstract: A 1,2-hydride shift in the phosphoric acid-promoted cyclodimerization of styrene oxide and its chloro derivatives under solvent-free conditions leading to 2,4-disubstituted 1,3-dioxolanes is described. Methoxy substituents on the aromatic ring of the styrene oxide prevent the 1,2-hydride shift reaction leading to substituted 1,4-dioxanes. A possible mechanism for the formation of the 1,3-dioxolanes is proposed. URI: http://hdl.handle.net/10311/1026 Files in this item: 1
Masesane_TL_2009.pdf (246.5Kb) -
Toteng, E.N. (Springer http://www.springerlink.com/index/05CM7XY4DJGUEUQL.pdf, NaN, 2001)[more][less]
Abstract: For the last three and half decades, Botswana has been widely acclaimed to be one of sub-Saharan Africa's longest and most stable liberal democracies, coupled with and sustained by a growing economy. One of the major contradictions, however, within this development scenario, has been the neglect of environmental problems in the country in general, and urban environmental issues in particular. Part of the problem fueling the misconception of environmental issues in Botswana is the state's domination of the country's environmental agenda. This is linked to the power disjunction in decision-making and policy processes between state and nonstate actors over the most appropriate course of action to tackle the problems. Without adopting appropriate analytical frameworks, it is possible that the problem of urban environmental mismanagement in Botswana will persist. This article examines some of the major urban environmental issues in Botswana from neighborhood, citywide, and urban–rural interface perspectives. Further, the elite theory of public policy is used to explain constraints on policy change in the urban environmental management arena in Botswana URI: http://hdl.handle.net/10311/365 Files in this item: 1
Toteng_EM_2001.pdf (933Kb) -
Gwebu, T.D. (Pergamon, www.elsevier.com/locate/habitatint, NaN, 2002)[more][less]
Abstract: In most sub-Sahara African cities, rapid urbanization has placed a heavy burden on available human, financial and socioeconomic resources. The problem has been compounded by the intricate and interactive effects of rapid population growth, the inability of local authorities to handle the increasingly complex functions of metropolitan management, centralization of decision-making by Central Governments, economic structural adjustment programmes, and even unfavourable variations in weather patterns. This is a historical case study, covering the period of roughly from 1989 to 1995. It is based on secondary sources, participation by the author in water supply feasibility investigations for Bulawayo, Zimbabwe, and views expressed in stakeholders’ meetings. It illustrates specifically how civic response has challenged the Central Government of Zimbabwe to review and revise its long-term water provisioning strategy for this municipal authority. URI: http://hdl.handle.net/10311/495 Files in this item: 1
GWEBU2002urbanWaters.pdf (1.681Mb)