Browsing Faculty of Science by Title
-
Nijegorodov, N.; Mabbs, R. (Elsevier Science BV; www.elsevier.com/locate/saa, January 15, 2002)[more][less]
Abstract: [Please note that the mathematical symbols have not transposed into this abstact].The luminescent and laser properties of heteroaromatic and aromatic compounds are reviewed and discussed on the basis of all possible mutual arrangements of singlet and triplet states. All heteroaromatic compounds are divided into five classes. It is shown that a heteroaromatic compound can only be an effective laser dye if it belongs to class V (a situation where the Tn_* level lies at higher energy than the S__* 1 level). Moreover, it is shown that the energy interval between the Tn_* and S__* 1 states must be no less than 1000 cmâ 1 since the rate constant of the non-radiative process S__*1 _Tn_*_T__1 is usually 100 times greater than the fluorescence rate constant. The classification is extended to compounds with orbitals of _l,_*, _,__* and _l,__* nature. Pure aromatic compounds, the spectral-luminescent properties of which are solely determined by transitions of _-electrons (_ _ _*), are also divided into five classes, depending on the mutual arrangement of the Sp(1La), S_(1Lb), Tp(3La) and T_(3Bb) states. It is found that only aromatic compounds of classes IV and V can be effective scintillators and laser dyes. It is also shown that the energy interval S_â Sp (for class IV) and T_â Sp (for class V) must be no less than 1000 cmâ 1. To illustrate the classifications for heteroaromatic and aromatic compounds, 12 specifically chosen compounds were studied experimentally and quantum chemically. The quantum yields, _ and decay times, _f of fluorescence in aerated and non-deaerated ethanol or cyclohexane solutions were measured. The oscillator strength, fe, fluorescence rate constant, kf, natural lifetimes, _0 T and intersystem crossing rate constants, kST are calculated. The laser ability of each of the compounds studied is tested. The suggested classification schemes can be extremely useful in the quest for effective scintillators and laser dyes among hypothetical heteroaromatic and aromatic molecules, enabling evaluation of these properties for a particular compound using only quantum chemical simulations. URI: http://hdl.handle.net/10311/136 Files in this item: 2
license.txt (1.998Kb)nijegorodov_sa_2002.pdf (1.811Mb) -
Muxworthy, A.R.; King, J.G.; Odling, N. (AGU and the Geochemical Society. http://www.agu.org/journals/gc/index.shtml, NaN, 2006)[more][less]
Abstract: The magnetic hysteresis properties for well-defined micron-sized magnetite samples produced by electron beam lithography (EBL) are presented. In addition to measuring standard hysteresis parameters, first-order reversal curve (FORC) diagrams are also reported. EBL produces samples that consist of particles with very tightly constrained size distributions, and spatial distributions that govern the degree of intergrain magnetostatic interactions are accurately controlled and known. Thus EBL samples are significantly better characterized compared to powdered samples, which are conventionally used to characterize the size dependency of magnetic hysteresis properties of naturally occurring magnetic minerals. Compared with the hysteresis properties of powdered samples of the same nominal sizes, EBL samples display more multidomain-like (MD) behavior. The influence of magnetostatic interactions fields on hysteresis properties is analyzed. When magnetostatic interactions are effectively in only one direction, the hysteresis properties become more single domain-like, and if the interactions are in more than one direction, hysteresis becomes more MD-like, in agreement with numerical models. URI: http://hdl.handle.net/10311/360 Files in this item: 1
Muxworthy_GGG_2006.pdf (1.589Mb) -
King, J G; Ranganai, RT (BOSHASTED, NaN, 2000)[more][less]
Abstract: Emissions of vehicles represent a significant contribution to environmental pollution along roads. Pollutants from cars include gases such as (NOx, CO, CO2), solid components such as sort particles from exhaust system, abrasion products from the brakes and engine etc (Leven et al., 1999). Aerosols pollutants can reduce significantly the quality of the environment and seriously affect human health e.g. by contributing to high rates of allergies or diseases of the respiratory system. In this study, samples were collected at various distances from a busy road, Gaborone-Tlokweng road near Game store. Non-magnetic adhesive paper pieces were used as sample collectors. Magnetic properties of the aerosols collected were measured using a highly sensitive magnetometer (AGM-Micromag). Magnetic properties measured include total magnetic moment, hysteresis loops and associated parameters such as coercivity. In general, observed hysteresis loops are typical for magnetite. URI: http://hdl.handle.net/10311/406 Files in this item: 1
King_BOSHASTED_2000.pdf (159.1Kb) -
Kampunzu, A.B.; Tombale, A.R.; Zhaia, M.; Bagai, Z.; Majaule, T.; Modisi, M.P. (Elsevier www.elsevier.com/locate/lithos, NaN, 2003)[more][less]
Abstract: The Neoarchaean Tati granite–greenstone terrane occurs within the southwestern part of the Zimbabwe craton in NE Botswana. It comprises 10 intrusive bodies forming part of three distinct plutonic suites: (1) an earlier TTG suite dominated by tonalites, trondhjemites, Na-granites distributed into high-Al (Group 1) and low-Al (Group 2) TTG sub-suite rocks; (2) a Sanukitoid suite including gabbros and Mg-diorites; and (3) a younger high-K granite suite displaying I-type, calc-alkaline affinities. The Group 1 TTG sub-suite rocks are marked by high Sr/Y values and strongly fractionated chondrite-normalized rare earth element (REE) patterns, with no Eu anomaly. The Group 2 TTG sub-suite displays higher LREE contents, negative Eu anomaly and small to no fractionation of HREE. The primordial mantle-normalized patterns of the Francistown TTGs are marked by negative Nb–Ti anomalies. The geochemical characteristics of the TTG rocks are consistent with features of silicate melts from partial melting of flat subducting slabs for the Group 1 sub-suite and partial melting of arc mafic magmas underplated in the lower crust for the Group 2 sub-suite. The gabbros and high-Mg diorites of the Sanukitoid suite are marked by Mg#>0.5, high Al2O3 (>>16%), low TiO2 ( < 0.6%) and variable enrichment of HFSE and LILE. Their chondrite-normalized REE patterns are flat in gabbros and mildly to substantially fractionated in high-Mg diorites, with minor negative or positive Eu anomalies. The primordial mantle-normalized diagrams display negative Nb–Ti (and Zr in gabbros) anomalies. Variable but high Sr/Y, Sr/Ce, La/Nb, Th/Ta and Cs/La and low Ce/Pb ratios mark the Sanukitoid suite rocks. These geochemical features are consistent with melting of a sub-arc heterogeneously metasomatised mantle wedge source predominantly enriched by earlier TTG melts and fluids from dehydration of a subducting slab. Melting of the mantle wedge is consistent with a steeper subduction system. The late to post-kinematic high-K granite suite includes I-type calc-alkaline rocks generated through crustal partial melting of earlier TTG material. The Neoarchaean tectonic evolution of the Zimbabwe craton is shown to mark a broad continental magmatic arc (and related accretionary thrusts and sedimentary basins) linked to a subduction zone, which operated within the Limpopo– Shashe belt atf2.8–2.65 Ga. The detachment of the subducting slab led to the uprise of a hotter mantle section as the source of heat inducing crustal partial melting of juvenile TTG material to produce the high-K granite suite. URI: http://hdl.handle.net/10311/381 Files in this item: 1
Kampunzu2003Majorandtrace element.pdf (2.863Mb) -
Simon, R.E.; Wright, C.; Kwadiba, M.T.O.; Kgaswane, E.M. (Elsevier Science Ltd. www.elsevier.com/locate/lithos, NaN, 2003)[more][less]
Abstract: Average one-dimensional P and S wavespeed models from the surface to depths of 800 km were derived for the southern African region using travel times and waveforms from earthquakes recorded at stations of the Kaapvaal and South African seismic networks. The Herglotz–Wiechert method combined with ray tracing was used to derive a preliminary P wavespeed model, followed by refinements using phase-weighted stacking and synthetic seismograms to yield the final model. Travel times combined with ray tracing were used to derive the S wavespeed model, which was also refined using phase-weighted stacking and synthetic seismograms. The presence of a high wavespeed upper mantle lid in the S model overlying a low wavespeed zone (LWZ) around 210- to - 345-km depth that is not observed in the P wavespeed model was inferred. The 410-km discontinuity shows similar characteristics to that in other continental regions, but occurs slightly deeper at 420 km. Depletion of iron and/or enrichment in aluminium relative to other regions are the preferred explanation, since the P wavespeeds throughout the transition zone are slightly higher than average. The average S wavespeed structure beneath southern Africa within and below the transition zone is similar to that of the IASP91 model. There is no evidence for discontinuity at 520-km depth. The 660-km discontinuity also appears to be slightly deeper than average (668 km), although the estimated thickness of the transition zone is 248 km, similar to the global average of 241 km. The small size of the 660-km discontinuity for P waves, compared with many other regions, suggests that interpretation of the discontinuity as the transformation of spinel to perovskite and magnesiowu¨ stite may require modification. Alternative explanations include the presence of garnetite-rich material or ilmenite-forming phase transformations above the 660-km discontinuity, and the garnet– perovskite transformation as the discontinuity. URI: http://hdl.handle.net/10311/265 Files in this item: 1
Simon_L71_2003.pdf (2.274Mb) -
De Waele, B.; Kampunzu, A.B.; Mapani, B.S.E.; Tembo, F. (Elsevier www.elsevier.com/locate/jafrearsci, NaN, 2006)[more][less]
Abstract: The Mesoproterozoic Irumide belt is a northeast-trending structural province stretching from central Zambia to the Zambia–Tanzania border and northern Malawi. Mesoproterozoic and Neoproterozoic transcurrent shear zones within reactivated parts of the Palaeoproterozoic Ubendian belt define its northeastern limit. The northwestern margin is defined by the largely undeformed basement lithologies of the Bangweulu block. An intensely folded and sheared zone at the southeastern margin of the Mporokoso Group sedimentary depocentre on the Bangweulu block, interpreted to have developed above a thrust at the basement-cover interface, indicates that far-field effects of the Irumide Orogen also affected the southeastern part of the Bangweulu block sedimentary cover. To the west and southwest, Irumide and basement lithologies were reworked by the Damara–Lufilian–Zambezi Orogen within the Neoproterozoic Zambezi and Lufilian belts. The Choma–Kalomo block, previously regarded as the southwesterly continuation of the Irumide belt, is a distinct Mesoproterozoic province, while a succession of structurally juxtaposed tectonic terranes in eastern Zambia record a deformation event related to the Irumide Orogen. The lithological units identified in the Irumide belt include: (1) limited Neoarchaean rocks emplaced between 2.73 and 2.61 Ga and representing the oldest rocks in the Bangweulu block; (2) ca. 2.05–1.85 Ga volcano-plutonic complexes and gneisses representing the most important components in the Bangweulu block; (3) an extensive quartzite–metapelite succession with minor carbonate forming the Muva Supergroup, and deposited at ca. 1.85 Ga; (4) granitoids emplaced between 1.65 and 1.55 Ga; (5) a minor suite of anorogenic plutons (nepheline syenite and biotite granite) restricted to the far northeastern Irumide belt and emplaced between 1.36 and 1.33 Ga; (6) voluminous syn- to post-kinematic Irumide granitoids emplaced between 1.05 and 0.95 Ga. Crustal shortening and thickening in the Irumide belt are shown by northwestward-directed thrusts and related folds and metamorphic parageneses recording a clockwise medium-pressure/medium-temperature P–T–t path. Metamorphic grades range from greenschist facies in the foreland to the northwest to upper amphibolite facies in the southeast, with local granulites. Peak metamorphism is diachronous across the belt and bracketed between 1.05 in the southeast and 1.02 Ga in the northwest. URI: http://hdl.handle.net/10311/398 Files in this item: 1
-
Becker, T.; Schreiber, U.; Kampunzu, A.B.; Armstrong, R. (Elsevier www.elsevier.com/locate/jafrearsci, NaN, 2006)[more][less]
Abstract: Two main Mesoproterozoic provinces occur in southern Namibia: (1) The high-grade Namaqua Metamorphic Complex (NMC) composed of a supracrustal sedimentary succession and interpreted as a passive margin sequence in the west of the Kalahari craton; (2) The Sinclair Group and its northeastern correlatives, composed of two main magmatic and metamorphic units, reflecting northeast-directed subduction, which started before 1.37 Ga and lasted until about 1.1 Ga. These two units were tectonically juxtaposed during the 1.1– 1.03 Ga Namaqua orogenic event. The Kairab–Kumbis Metamorphic Complex comprises metasedimentary and metavolcanic rocks intruded by the 1.37 Ga arc-related Aunis tonalite. The mafic volcanic rocks from this complex have geochemical features of island arc calcalkaline basalts; they were emplaced and metamorphosed along an active margin before 1.37 Ga. The 1.2–1.1 Ga low-grade unmetamorphosed volcanic and immature sedimentary rocks of the Sinclair Group and its northwestern equivalents rest disconformably on the Kairab–Kumbis Complex. They occur in fault-bounded depocenters defining a regional arc-shape structure up to 100 km-wide and with a minimum length of 2000 km. The plate tectonic setting of this arc is best constrained by the composition of volcanic rocks from the 1.2 Ga Barby Formation and coeval granitoids; they comprise high-K calcalkaline rocks suggesting emplacement in an active continental margin setting. The final stage of this continental arc evolution is recorded in the <1.1 Ga tholeiites of the Opdam Formation. High Ti-content and flat REEpatterns in the tholeiites suggests an extensional event, whereas high Th/Ta and La/Nb ratios, low Ce/Pb values and negative anomalies for Nb–Ta suggest a subduction-related setting for the mantle source from which the mafic magmas were derived. Docking of continents led to the slab detachment, allowing interaction between the asthenospheric mantle and the mantle wedge enriched during the subduction process. The magmatic underplating related to this event induced the genesis of large-scale batholitic granitoid bodies in the NMC and a 1.1–1.0 Ga high-grade LP/HT metamorphism, with mineral assemblages indicating an anti-clockwise P–T–t path. URI: http://hdl.handle.net/10311/385 Files in this item: 1
Kampunzu2006RocksofNamibia.pdf (3.444Mb) -
Atlhopheng, J.R.; Ekosse, G. I. E. (Bioline http://www.bioline.org, NaN, 2007)[more][less]
Abstract: A mineralogical investigation of duricrust suites in Letlhakeng valley, and five pans around Jwaneng in Botswana was undertaken in order to know the mineral assemblages and infer on their landscape formation. In Letlhakeng, duricrusts comprised calcretes, silcretes and ferricretes. Calcretes were dominated by the minerals: calcite, quartz and to a lesser extent dolomite. Silcrete mineralogy was dominated by quartz, opal, and some occurrences of palygorskite, microcline and rutile. The intermediate forms of cal-silcretes yielded quartz, muscovite, and kaolinite. Ferricretes occurred on an area of the valley capping, with minerals dominated by goethite and haematite. The indurates are believed to have been formed through groundwater mechanisms. The general lowering of the valley, led to precipitation of the duricrusts. The pans were dominated by calcrete and silcrete only. The calcretes mineralogy was mainly calcite, dolomite and quartz. Illite-montmorillonite and sepiollite were also present. Samples of pan clay floor, other than being dominated by calcite, dolomite and quartz, also had sepiollite ferrian. Pans and valleys are accumulation sites, with polygenetic modes of genesis. The duricrusts have undergone several alterations throughout time. URI: http://hdl.handle.net/10311/679 Files in this item: 1
Atlhopheng_JASEM_2007.pdf (494.4Kb) -
Meck, M.L.; Atlhopheng, J.; Masamba, W.R.L.; Ringrose, S.; Diskin, S. (Bentham Open, http://www.benthamscience.com/open/tomj/index.htm, NaN, 2011)[more][less]
Abstract: This study set out to establish the major minerals at Dorowa and determine which of those are likely to host metals that may leach into surface and groundwater. This study comes after a preliminary assessment of the water quality in the Save River downstream of the Dorowa phosphate mine in Zimbabwe showed an increase in conductivity, iron content, manganese content, nitrates and hardness when compared to those taken before the mining area. X-Ray Diffractometry (XRD) was used to establish the major minerals at Dorowa whilst Inductively Coupled Plasma Mass Spectrometry (ICP- MS) was used to establish the chemistry of the rocks. The results from this study show that the major minerals in the rocks around Dorowa are feldspars, pyroxenes, apatite, magnetite and calcite. The metals hosted by the rocks include Ag, As, Be, Cd, Co, Cu, Pb, Hg, Ni, Sb, Se and Zn. The study concludes that the minerals likely to host metals are calcite and apatite. Metal hosting is higher in apatite minerals than in calcite. Metal hosting by the other minerals observed in the study area is low. URI: http://hdl.handle.net/10311/1109 Files in this item: 1
Atlhopheng_OMJ_2011.pdf (848.6Kb) -
Matsheka, M.I.; Lastovica, A.J.; Elisha, B.G. (American Society for Microbiology. http://jcm.asm.org/, NaN, 2001)[more][less]
Abstract: A 1.6-kb DNA fragment isolated from a Campylobacter concisus genomic library gave C. concisus-specific restriction fragment length patterns when it was used as a probe in hybridization studies. All of the strains tested, including type strains and clinical isolates, contained a 0.5-kb HindIII fragment that hybridized to the probe. DNA sequencing of the 1.6-kb fragment identified three open reading frames (ORFs). One of the ORFs encodes the carboxy terminus of GyrB, and the translational products of ORF2 and ORF3 showed similarity to hypothetical proteins, previously identified in Campylobacter jejuni. DNA-DNA hybridization studies with a fragment internal to ORF3 showed that this sequence was responsible for the signal observed with the 0.5-kb HindIII fragment. A rapid PCR assay was developed and evaluated. Primers that annealed to the extremities of the 1.6-kb fragment were used to obtain an amplicon of the correct size from both reference and clinical strains of C. concisus. URI: http://hdl.handle.net/10311/306 Files in this item: 1
Molecular identification of.pdf (4.701Mb) -
Mogobe, K.D.; Tshiamo, W.; Bowelo, M. (Elsevier, www.rhmjournal.org.uk, NaN, 2007)[more][less]
Abstract: This paper describes the maternity monitoring system in Botswana, developed in 1998, and the main methods used: maternal death and morbidity reviews at service delivery level, analysis by the National Maternal Mortality Audit Committee of data from the reviews as reported on two forms, perinatal reviews and surveys using process indicators. We carried out a study of these findings to examine whether the system was working well. Surveys using process indicators in 2001 and 2006 were analysed. Other data examined were from 2004–2006 and early 2007. The Maternal Death Notification Form was found to be comprehensive but not all health facilities were submitting them and some gave incomplete information. In 2001, 70% of pregnant women attended antenatal care but access to emergency obstetric care was uneven. In 2006, 28 facilities with maternity services surveyed were providing 24-hour delivery care, but laboratory, theatre and blood supplies were more limited, and only 50% of doctors and 67% of midwives had life-saving skills. Antibiotics were widely available, but there were shortages of magnesium sulphate, diazepam, oxytocics and manual vacuum aspiration kits. Recommendations for improvements have been made, training for skilled attendants is ongoing and a medical school has just opened at the University of Botswana. URI: http://hdl.handle.net/10311/498 Files in this item: 1
DintleMogobe2007Mortality.pdf (944.3Kb) -
Gnonlonfin, G.J.B.; Hell, K.; Fandohan, P.; Siame, A.B. (Elsevier B.V. www.elsevier.com/locate/ijfoodmicro, NaN, 2008)[more][less]
Abstract: The presence of fungi, aflatoxins and fumonisin B1 in cassava and yam chips (during 28 processing and storage) were evaluated during two consecutive seasons in two agroecological zones of Benin (Northern Guinea Savannah, NGS and Sudan Savannah, SS). The Benin samples were assessed for moisture content, fungal infestation and total aflatoxin and fumonisin B1 contamination. During the two seasons, samples collected from the NGS, had moisture contents ranging from 10.0 to 14.7% in cassava chips and from 11.4 to 15.3% in yam chips. In samples from the SS, moisture content ranged from 10.1 to 14.5% and 11.1 to 14.5% in cassava and yam chips, respectively. A. flavus was the predominant fungal species. The maximum cfu/g in cassava and yam chips was 8950 and 6030, respectively. Other fungal species isolated included P. chrysogenum, M. piriformis, Phoma sorghina, F. verticillioides, R. oryzae and Nigrospora oryzae. High performance liquid chromatography analysis of both cassava and yam chips showed no contamination by either aflatoxins or fumonisin B1. URI: http://hdl.handle.net/10311/317 Files in this item: 1
Mycoflora and natural occurrence.pdf (5.959Mb) -
Cao, Y.; Allameh, S.; Sethiaraj, S. (Elsevier, NaN, 2006)[more][less]
Abstract: This paper presents the results of nanoindentation experimental studies of the contact-induced deformation in Au and Ag thin films. The paper examines the effects of film thickness and substrate deformation restraint on the mechanical properties of electron beam (e-beam) deposited Au and Ag films. Following a brief description of film microstructure, surface topography, and contact-induced pile-up deformation, film mechanical properties (hardness and Young’s modulus) were determined using nanoindentation techniques. The indentation size effects (ISE) observed in films with different thicknesses were explained using a mechanism-based strain gradient (MSG) theory. The intrinsic film yield strengths and hardnesses extracted from the MSG theory are shown to exhibit classical Hall–Petch dependence on the inverse square root of the average film grain size. Displacement bursts were also found to occur in Ag films at indentation load levels of 100 N. These were attributed to the initial onset of dislocation slip activity, when the shear stress exceeds the estimated theoretical shear strengths of the materials. URI: http://hdl.handle.net/10311/537 Files in this item: 1
Nanoindentation measurements.pdf (1.173Mb) -
Meck, M.L.; Masamba, W.R.L.; Atlhopheng, J.; Ringrose, S. (Elsevier Science Ltd, http://www.elsevier.com/locate/pce, NaN, 2011)[more][less]
Abstract: The objective of the study was to investigate the role played by the natural environment in protecting the transboundary Save River from the impacts of metals derived from phosphate mining at Dorowa. The study is a follow up study from a previous one that noted that there is natural attenuation at Dorowa. Water and sediment samples were collected in the Save River and the streams that drain the Dorowa dumps. Inductively coupled plasma mass spectrometry (ICP–MS) was used to analyze the cations (Na+, K+, Ca2+, Mg2+, Cu2+, Co2+, Fe2+, Ni2+, Zn2+, Pb2+, Sn2+, Mn2+, Cd2+) in the samples. Major anions Cl , SO2 4 and NO 3 were analyzed by standard chromatography whilst CO2 3 and HCO 3 were determined by titration. pH was measured on site. Geochemical modeling of the water composition was conducted with Visual Minteq. The results show that natural attenuation is being achieved through precipitation of solids from the water and subsequent deposition onto the sediments. Six of the metals are almost completely precipitated (Cu 99.99%, Fe 99.39%, Ni 91.24%, Pb 99.87%, Sn 99.99% and Zn 88.66%). However Mn, Co and Cd remain in solution. Thus the natural environment is protecting the Save River which is a transboundary river from the impacts of mining through precipitation of the metals. Users downstream of Dorowa mine are therefore not being affected by mining pollution. This study demonstrates that besides being a legitimate and important user of water, the natural environment can also play a significant role in protecting water quality by attenuating metals naturally. By analyzing costs incurred in several places where alternative methods are employed to remediate metal related pollution the study concludes that natural remediation at Dorowa is saving the nation in environmental costs. Therefore the paper advocates for appreciation of the role that the natural environment plays in protecting ecosystems from the impact of human developments and environmental costs. Subsequently, this calls for recognition of natural environment’s role in water resources management for the sustenance of ecosystems and peoples livelihoods. URI: http://hdl.handle.net/10311/963 Files in this item: 1
Atlhopheng_PCE_2011.pdf (630.3Kb) -
Murty, V.R.K.; Karunakara, N. (Elsevier, www.elsevier.com/locate/radmeas, NaN, 2008)[more][less]
Abstract: Studies on concentrations of primordial radionuclides in soil samples of Botswana were carried out. Measurements were made by gamma spectrometry employing a 41% relative efficiency HPGe detector. The activity of 226Ra was found to vary in the range 6.1–97.4 Bq kg 1 with a mean value of 34.8 Bq kg 1, 232Th in 7.4–110.0 Bq kg 1 with a mean value of 41.8 Bq kg 1 and that of 40K between 33.5 and 1085.7 Bq kg 1 with a mean value of 432.7 Bq kg 1 in surface soils. Existence of strong correlations in the distributions of these radionuclides indicates that an individual result for any one of the radionuclide is a good predictor of the concentration of the other. The mean value of effective dose, due to the 238U series, 232Th series and 40K in soil, was 0.07 mSV. The results of the present study are compared with the literature values reported for other normal background regions of the world and discussed. URI: http://hdl.handle.net/10311/493 Files in this item: 1
Murty2008SoilSamples.pdf (782.0Kb) -
Hambira, W.L. (Elsevier, http://www.elsevier.com/wps/find/journaldescription.cws_home/413/description#description, NaN, 2007)[more][less]
Abstract: Natural Resource Accounting (NRA) has become an important environmental/natural resources management tool in recent years. It provides information on stocks of a resource available at a particular point in time and what activities the resource is being used for. The conventional System of National Income Accounts (SNA) normally does not capture the cost of depletion, degradation or pollution of natural resources. This encourages unsustainable use of natural resources since the costs are not reflected when assessing the country’s economic performance or development progress. NRA is thus an attempt to integrate environmental issues into the conventional national accounts. The water sector is one sector that could greatly benefit from this natural resource management tool. Botswana has adopted NRA as a natural resource management tool and has so far developed accounts for minerals, livestock and water. The focus of this paper is on Water Accounting (WA) in relation to Integrated Water Resources Management (IWRM). IWRM is concerned with coordinated development and management of water in order to maximise economic and social welfare without compromising the sustainability of ecosystems. WA helps fill data gaps since it provides the required information for IWRM to be achieved. The aim of this paper therefore is to evaluate the Water Accounts of Botswana Report of 2006 to determine the extent to which it can contribute to integrated water resources management. The paper is based on literature review and the results show that: the available water stocks vary depending on rainfall patterns, well fields are over utilised, there has been growth in consumption, and more than 80% of the waste water produced is not being put to use. These results calls for changes in policies, role of institutions and practices pertaining to water resources management which is what IWRM is all about hence the paper concludes that indeed WA can contribute to the realisation of IWRM. URI: http://hdl.handle.net/10311/283 Files in this item: 1
-
Cailteux, J.L.H.; Kampunzu, A.B.; Lerouge, C. (Elsevier www.elsevier.com/locate/gr, NaN, 2007)[more][less]
Abstract: Rocks of the Neoproterozoic Mwashya Subgroup (former Upper Mwashya) form the uppermost sedimentary unit of the Roan Group. Based on new field and drill hole observations, the Mwashya is subdivided into three formations: (1) Kamoya, characterized by dolomitic silty shales/ siltstones/sandstones and containing a regional marker (the “Conglomerate de Mwashya” bed or complex); (2) Kafubu, formed by finely bedded black carbonaceous shales; and (3) Kanzadi, marked by feldspathic sandstones. Rocks of the Mwashya Subgroup are overlain by the Sturtian age Grand Conglomérat diamictite (equivalent to the Varianto/Brazil and Chuos/Namibia diamictites), and conformably overlie rocks of the Kansuki Formation (former Lower Mwashya), a carbonate unit containing volcaniclastic beds. New geochemical data confirm the continental rift context of this magmatism, which is contemporaneous with rift-related volcanism of the Askevold Formation (Nosib Group, Namibia). A gradational lithological transition between rocks of the Kansuki and the underlying Kanwangungu Formations, and similar petrological composition of these two formations, support the hypothesis that the Kansuki is the uppermost unit of the carbonate-dominated Dipeta/Kanwangungu sequence, and does not form part of the Mwashya Subgroup. Base metal deposits, mostly hosted in rocks of the Kansuki Formation, include weakly disseminated early-stage low-grade Cu–Co mineralisation, which was reworked and enriched, or initially deposited, by metamorphic fluids associated with the Lufilian orogenic event. URI: http://hdl.handle.net/10311/399 Files in this item: 1
Kampunzu2007Neoproterozoic Mwashya.pdf (2.801Mb) -
Ntshwene, K.; Kashiwagi, J.; Kashiwagi, D. (Royal Institute of Chartered Surveyors http://www.rics.org/site/download_feed.aspx?fileID=5042&fileExtension=PDF, NaN, 2009)[more][less]
Abstract: The traditional contracting/delivery system in Botswana, introduced by the US, UK, and European educators, consultants, and practitioners, has not been working well in Botswana. The poor project delivery system results have forced the organization of a new group, the Government Implementation Coordination Group (GICO) to attempt to solve the problems. In the fall of 2008, the University of Botswana (UB), through the US State Department sponsored Fulbright program, brought professor Kashiwagi, and the best value Performance Information Procurement System (PIPS) technology, the Information Measurement Theory (IMT), and the Industry Structure Analysis to the UB project management section. This paper proposes that the client’s professional representative requires a new, more effective role. The role includes using performance information, transforming the client’s expectations into a design/construction intent by using expert vendors, ensuring the vendors manage and minimize the risk that they do not control, outsourcing the technical responsibilities, and doing quality assurance instead of quality control. This paradigm will minimize project risk, maximize project value, and increase the professionalism of project management, construction management, and quantity surveyors. These concepts will be tested on three test projects in Botswana. URI: http://hdl.handle.net/10311/473 Files in this item: 1
Ntshwene_COBRA_2009.pdf (1.344Mb) -
Aranibar, J.N.; Otter, L.; Macko, S.A.; Feral, C.J.W.; Epstein, H.E.; Dowty, P.R.; Eckardt, F.; Shugart, H.H.; Swap, R.J. (Blackwell Publishing, January 1, 2004)[more][less]
Abstract: Nitrogen (N) cycling was analyzed in the Kalahari region of southern Africa, where a strong precipitation gradient (from 978 to 230mm mean annual precipitation) is the main variable affecting vegetation. The region is underlain by a homogeneous soil substrate, the Kalahari sands, and provides the opportunity to analyze climate effects on nutrient cycling. Soil and plant N pools, 15N natural abundance (d15N), and soil NO emissions were measured to indicate patterns of N cycling along a precipitation gradient. The importance of biogenic N2 fixation associated with vascular plants was estimated with foliar d15N and the basal area of leguminous plants. Soil and plant N was more 15N enriched in arid than in humid areas, and the relation was steeper in samples collected during wet than during dry years. This indicates a strong effect of annual precipitation variability on N cycling. Soil organic carbon and C/N decreased with aridity, and soil N was influenced by plant functional types. Biogenic N2 fixation associated with vascular plants was more important in humid areas. Nitrogen fixation associated with trees and shrubs was almost absent in arid areas, even though Mimosoideae species dominate. Soil NO emissions increased with temperature and moisture and were therefore estimated to be lower in drier areas. The isotopic pattern observed in the Kalahari (15N enrichment with aridity) agrees with the lower soil organic matter, soil C/N, and N2 fixation found in arid areas. However, the estimated NO emissions would cause an opposite pattern in d15N, suggesting that other processes, such as internal recycling and ammonia volatilization, may also affect isotopic signatures. This study indicates that spatial, and mainly temporal, variability of precipitation play a key role on N cycling and isotopic signatures in the soil–plant system. URI: http://hdl.handle.net/10311/577 Files in this item: 1
ARANIBAR2004NITROGEN CYCLING.pdf (2.135Mb) -
Abegaz, B.M.; Ngadjui, B.T.; Bezabih, M.; Mdee, L.K. (International Union of Pure and Applied Chemistry. http://www.iupac.org/publications/pac/, NaN, 1999)[more][less]
Abstract: Marketed plants are an important but a vulnerable group of plants whose investigations as well as conservation should be considered with priority. The chemistry, and in some cases biological activities of novel iso¯avonoids, nor-lignans, anthracene and naphthalene derivatives and poly prenylated ¯avonoids isolated and characterized from Hagenia abyssinica, Salsola somalensis, Hypoxis spp., Taverniera abyssinica, Aloe spp., Bulbine capitata, Rhamnus prinoides and Dorstenia spp. are discussed. URI: http://hdl.handle.net/10311/289 Files in this item: 1
Novel natural products.pdf (4.533Mb)