Browsing by Title
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Kumar, J.; Ahmad, M.; Chander, R.; Thangaraj, R.; Sathiaraj, T.S. (EDP Sciences. http://www.epjap.org/, NaN, 2008)[more][less]
Abstract: Effect of Pb substitution on the amorphous-crystalline transformation temperature, optical band gap and crystalline structure of Ge2Sb2Te5 has been studied. In Pb:GeSbTe chalcogenide films prepared by thermal evaporation, an amorphous to crystallization transition is observed at 124, 129, 136 and 138 ◦C in Pb0Ge20Sb24Te56, Pb1.6Ge19Sb26Te54, Pb3Ge17Sb28Te53 and Pb5Ge12Sb28Te55 respectively. XRD investigations of annealed samples reveal that Pb substitution retains NaCl type crystalline structure of GST but expands the lattice due to large atomic radii. The increase in amorphous-crystalline transformation temperature is followed with the increase in phase segregation. The optical gap shows marginal variations with composition. URI: http://hdl.handle.net/10311/278 Files in this item: 1
Kumar_EPJAP41_2008.pdf (796.1Kb) -
Goodwin, J.W.; Hughes, R.W.; Kwaambwa, H.M.; Reynolds, P.A. (Elseview Science B.V. www.elsevier.nl/locate/colsurfa, NaN, 2000)[more][less]
Abstract: A series of well characterised cis-polyisoprene polymers have been added to dispersions of PHS coated PMMA particles in dodecane. At a molecular weight of 8000 g mol−1 and above, these systems showed phase separation at low particle volume fractions and above a critical polymer concentration. The rate of separation has been shown to be influenced by the viscosity of the polymer. At high polymer and particle volume fractions long lived metastable phases occurred. Above a critical concentration these were viscoelastic indicating an appreciable change in diffusion dynamics with two relaxation processes present. A significant Bingham yield stress was also observed. The Asakura Oosawa potential was not able to describe the observed rheological properties. At a molecular weight of 1000 g mol−1 no phase separation was observed. At high particle concentrations the yield stress was found to reduce with the addition of polymer. This was due to the polymer acting as a ‘solvent’ and penetrating the stabilising layer on the particles. URI: http://hdl.handle.net/10311/329 Files in this item: 1
Phase separation behaviour.pdf (2.723Mb) -
Kezilahabi, E. (Taylor and Francis, NaN, 2001)[more][less]
Abstract: This article argues that greeting among the Kerebe is a phenomenological project of everydayness in which the concept of being manifests itself in a dialogic manner. This is revealed through the four variables on which greetings are based: time, age, gender and relationship. The variables give us a glimpse of how the Kerebe view the question of temporality of being, the idea of being-for-the-other and the question of truth; and they cast some light on the general concept of a person in Kerebe thought. The article is oriented toward an inquiry into the concept of being-in-the-world from an African point of view. URI: http://hdl.handle.net/10311/421 Files in this item: 1
Kezilahabi_JACS_2001.pdf (1.480Mb) -
Munkombwe N.M. (Elsevier Ltd. www.elsevier.com/locate/phytochem, NaN, 2003)[more][less]
Abstract: Two phenylpropanoid glucosides, 2-O-b-d-glucosyloxy-4-methoxybenzenepropanoic acid and its methyl ester, together with syringin and adicardin were isolated from the stem of Gnidia polycephala and characterized by physical and spectroscopic data. URI: http://hdl.handle.net/10311/275 Files in this item: 2
Phenylpropanoid glycosides.pdf (2.288Mb)Phenylpropanoid glycosides of Gnidia.pdf (155.6Kb) -
Nijegorodov, N.; Zvolinski, V.; Luhanga, P.V.C.; Mabbs, R.; Ahmad, J. (Elsevier Ltd. www.elsevier.com/locate/saa, NaN, 2006)[more][less]
Abstract: The multi-banded fluorescence and laser properties of 11 new amino- and tosylamino derivatives of 2,5-di(phenyl)-1,3,4-oxadiazole and oxadiazole in various solvents at 293 K are reported. All the compounds investigated possess intra-molecular hydrogen quasi-bond (IHB) of 4.6-5.2 kcal mol-1 in the ground state. In the excited state they can undergo protolytic dissociation or intra-molecular photon-initiated transfer of proton and reveal anomalous fluorescence which cannot be explained within the framework of the Kasha and Kasha-Vavilov rules. Depending upon the excitation wavelength, solvent, concentration and pH of the medium, the compounds studied show a single, double, triple or even a four-banded fluorescence, which has not been reported earlier. The nature of multi-banded fluorescence is explained in terms of the possible photochromic processes in excited states. Quantum yields and decay times of the different fluorescence bands are reported. Anomalous dependence of quantum yield upon concentration of the solution is observed. Laser properties of the compounds studied are carefully tested. Laser action based on the fluorescence of the so-called bi-radical molecules is reported. Various possible arrangements of singlet and triplet levels of compounds investigated are discussed. URI: http://hdl.handle.net/10311/176 Files in this item: 2
license.txt (1.998Kb) -
Nijegorodov, N; Zvolinski, V; Luhanga, P V C; Mabbs, R; Ahmad, J (Elsevier Science Ltd. www.elsevier.com/locate/saa, NaN, 2006)[more][less]
Abstract: The multi-banded fluorescence and laser properties of 11 new amino- and tosylamino derivatives of 2,5-di(phenyl)-1,3,4-oxadiazole and oxadiazole in various solvents at 293K are reported. All the compounds investigated possess intra-molecular hydrogen quasi-bond (IHB) of 4.6–5.2 kcal mol−1 in the ground state. In the excited state they can undergo protolytic dissociation or intra-molecular photon-initiated transfer of proton and reveal anomalous fluorescence which cannot be explained within the framework of the Kasha and Kasha–Vavilov rules. Depending upon the excitation wavelength, solvent, concentration and pH of the medium, the compounds studied show a single, double, triple or even a four-banded fluorescence, which has not been reported earlier. The nature of multi-banded fluorescence is explained in terms of the possible photochromic processes in excited states. Quantum yields and decay times of the different fluorescence bands are reported. Anomalous dependence of quantum yield upon concentration of the solution is observed. Laser properties of the compounds studied are carefully tested. Laser action based on the fluorescence of the so-called bi-radical molecules is reported. Various possible arrangements of singlet and triplet levels of compounds investigated are discussed. URI: http://hdl.handle.net/10311/247 Files in this item: 2
license.txt (1.998Kb)Nijegorodov_SAa65_2006.pdf (2.225Mb) -
Murty, V.R.K.; Devan, K.R.S. (Elsevier Science Ltd. www.elsevier.com/locate/radphyschem, NaN, 2004)[more][less]
Abstract: The interaction of photons with matter has been extensively studied over the past several decades in view of its importance in basic radiation physics research, medical, industrial and other applied fields. Large amounts of data have been complied on photon cross sections mostly in tabular and graphical forms (Hubbell, 1999, 1994; Berger and Hubbell, 1987). A careful survey of the latest bibliography (Hubbell, 1994) of experimental investigations shows gaps in the cross section data, especially in certain low-Z elements. These are mainly attributed to the difficulty in procuring thin absorbers in suitable form for low energy experiments. It was also evident from the bibliography that the cross section data was sparse for elements Mg and V, especially, using high resolution solid state detectors in the photon energy region below 100 keV. URI: http://hdl.handle.net/10311/266 Files in this item: 1
Murty_RPC_2004.pdf (191.6Kb) -
Nijegorodov, N.; Zvolinsky, V.; Luhanga, P.V.C. (Elsevier Science Ltd. www.elsevier.com/locate/jphotochem, NaN, 2008)[more][less]
Abstract: Intramolecular processes and fluorescence properties of 32 specially chosen aromatic molecules, different in degrees of planarity and rigidity, but family related in -structure are experimentally and theoretically (using the PPP-method) studied at room temperature (293 K). The quantum yields of fluorescence , and decay times τf, of deaerated and non-deaerated cyclohexane solutions are measured. The oscillator strength fe, the fluorescence rate constants kf, the natural lifetimes τT o , and the intersystem crossing rate constants kST, are calculated. The investigations showed the following differences in the behaviour of the fluorescence parameters in transition from the non-planar molecule to the planar and more rigid-type: the value of the symmetry line wave-number υ00 (the frequency of the S0→S1 * transition) and the Stokes shift υST, decrease. The oscillator strength and fluorescence constant, normally decrease. The change in the quantum yield of the fluorescence depends upon the changes in the kf and kST values. Furthermore, the intersystem crossing rate constant generally decreases, sometimes very significantly. However, there are some interesting exceptions. For example, the kST value of the non-planar molecule of 9,10-diphenylanthracene is less than the kST value of the planar and very rigid molecule of anthracene. This important phenomenon is explained. The differences of the intramolecular processes of planar and non-planar molecules are discussed. The photochemical stability of planar and non-planar molecules is studied. The effect of planarity, rigidity and molecular symmetry upon laser properties is also traced. URI: http://hdl.handle.net/10311/367 Files in this item: 1
Nijegorodov_JPPaC196_2008.pdf (1.901Mb) -
Physically active lifestyle and the development and sustenance of healthy human and economic sourcesOnyewadume, I.U. (Boleswa, http://bera.co.bw, NaN, 2002)[more][less]
Abstract: Dedicated participation in leisure/recreational and competitive physical activities have been known to develop the physical fitness and the physical working capacity (PWC) of the individuals concerned. In the same vein, improved physical fitness and PWC lead to improved productivity in any group of people in their various professions. The ultimate goal of any profession is the provision of abundant economic and material benefits through the development of fit and capable human resouces. Thus, this paper aims at bringing to the fore the modalities through which a countyr's human resource can be galvanized into a fit and physically empowered factor of production for the achievement of material and economic prosperity. URI: http://hdl.handle.net/10311/721 Files in this item: 1
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Mphale, K.M.; Heron, M.L. (Elsevier Science Ltd. www.elsevier.com/locate/jastp, NaN, 2007)[more][less]
Abstract: The flames of wildfires are weakly ionized gas. The ionization is mainly due to omnipresent alkali and alkaline earth metal species that are emitted from thermally decomposing plant structure into the flame during a wildfire. The amount of ionization in flames with alkali impurities is a factor of both the temperature and the quantity of the emitted alkali species in vegetation. Assuming a Maxwellian velocity distribution of flame particles and collision frequencies much higher than plasma frequencies, the propagation of radio waves through wildfires is predicted to have attenuation and phase shift. A theoretical model has been developed to predict propagation characteristics of HF–VHF radio signals at normal incidence to a high intensity wildfire fuel–flame interface. At the interface, the flame medium is modelled by a series of mini-slabs, each with a different but fixed electron density and dielectric permittivity governed by the Rayleigh distribution of temperature. Electron density in each mini-slab is calculated from thermal ionization of alkali species assuming the existence of thermal equilibrium. The model predicts average electron densities ranging from 10¹4 to 10¹7m–³ for fuel–flame interfaces with maximum temperatures from 900 to 1200 K. Specific attenuation and phase shift for propagation in the ionized gas are calculated from the predicted average electron density and collision frequency. At collision frequency of 10¹¹ s–¹, radio signal specific attenuation for the simulated grassfires range from 0.001 to 0.49 dBm–¹ while specific phase shift ranged from 0.0002 to 152°m–¹ for the maximum temperature range of 900–1150 K. URI: http://hdl.handle.net/10311/269 Files in this item: 1
Mphale_JASTP69_2007.pdf (2.265Mb) -
Garg, A.K.; Van Tonder, R.; Joubert, R.J.O. (Inderscience Enterprises Ltd. http://www.inderscience.com/browse/index.php?journalID=235, NaN, 2007)[more][less]
Abstract: In order to analyse the strategic issues with regard to the South African Platinum Group of Metals (PGM) industry, a risk analysis and an assessment of the competitiveness of the industry were conducted. The analysis of risk related to market conditions indicates a relatively low risk rating driven by increased demand for jewellery and autocatalysts, while the industry is exposed to moderate risk for raw materials and supporting services, which is expected to remain moderate in future. Overall, the current risk for production factors was found to be moderate and is expected to remain moderate over the medium term. The results of industry risk analysis indicate that the PGM industry is currently exposed to moderate risk. Applying Porter’s diamond model (Porter, 1990), the research found that the South Africa’s PGM industry has a very strong platform and is expected to become more competitive in future, although increased cooperation will still be evident. The competitiveness of South African producers is expected to increase over the medium term, since most of the expansion will come on stream in the near future. The paper also discusses the development potential of South Africa in line with the exploitation of PGM. URI: http://hdl.handle.net/10311/295 Files in this item: 1
Garg_IGICBM_2007.pdf (2.472Mb) -
Marobela, M.N.; Mawere, S.P. (Academic Journals, http://www.academicjournals.org, July 4, 2011)[more][less]
Abstract: This paper explores the implementation of public sector performance reforms in Botswana magistrate courts to improve service delivery. The authors argue that it is imperative for management to consider the possibility of the unintended outcomes in public sector reforms something that is normally ignored when introducing change. Critical realist philosophy has been adopted as a guiding paradigm for this study. The main contention is that the social world exists independently of the researcher. In this study realist philosophy was used together with the case study methodology to give context. In the courts performance management was supposed to help improve service delivery by reducing court congestion, legal costs, and delays. However, the findings suggest that this has not been the case because of gaming and manipulation of performance measures. A principal constraint in writing this paper was the absence of relevant literature in Botswana. Data was sourced from one organisation used as a case study. Problems like the backlogs of cases and delays affect both the fairness and efficiency of the judicial system. Efficiency has to take account of other factors. Developing performance management systems that incorporate measurement and evaluation in the public sector continues to be a key challenge. Both the positive and negative effects of PMS must be embraced. URI: http://hdl.handle.net/10311/1083 Files in this item: 1
Marobela and Mawere_AJBM_2011.pdf (1.154Mb) -
Kwadiba, M.T.O.G.; Wright, C.; Kgaswane, E.M.; Simon, R.E.; Nguuri, T.K. (Elsevier Science Ltd. www.elsevier.com/locate/lithos, NaN, 2003)[more][less]
Abstract: Pn arrivals from mining-induced earthquakes on the edge of the Witwatersrand basin show that the P wavespeeds in the uppermost mantle are almost constant throughout most of the Kaapvaal craton. The presence of only small wavespeed variations allows the use of a simple method of estimating crustal thicknesses below the stations of the Kaapvaal broad-band network using Pn times that has been compared with results from receiver functions. One thousand three hundred thirty-seven Pn arrivals were used to derive crustal thicknesses at 46 stations on the Kaapvaal craton. The average crustal thicknesses for 19 centrally located stations on each of the northern and southern regions of the craton that yielded well-constrained thicknesses were 50.52 ± 0.88 km and 38.07 ± 0.85 km, respectively. In contrast, the corresponding average thicknesses determined from receiver functions were 43.58 ± 0.57 km and 37.58 ± 0.70 km, respectively. The systematically lower values for receiver functions in the northern part of the Kaapvaal craton that was affected by the Bushveld magmatism at 2.05 Ga, suggest that the receiver functions do not enable the petrological crust mantle boundary to be reliably resolved due to variations in composition and metamorphic grade in a mafic lower crust. The Pn times also suggest pervasive azimuthal anisotropy with maximum wavespeeds of about 8.40 km/s at azimuths of about 15° and 217° in the northern and southern regions of the craton, respectively, and minimum wavespeeds of about 8.25 km/s. URI: http://hdl.handle.net/10311/281 Files in this item: 1
Kwadiba_L71_2003.pdf (2.747Mb) -
Maundeni, Z. (Academic Journals, http://www.academicjournals.org, April NaN, 2010)[more][less]
Abstract: This article considers Lesotho’s political history and culture, a political history characterised by rebellious chiefs who had rejected Christianity and who were heavily armed and fought numerous wars against their black and white neighbours. Its argument is that the state’s dysfunctionality in small Lesotho is a result of a political culture and history of armed resistance, producing rebellious political elites who feuded between themselves, against the colonial establishment and against the postcolonial government. It was also a political culture that rejected Christianity, accepted old leaders to die in office and encouraged factionalism. The political parties that emerged from such a political culture were traditionally oriented, radical, dominated by old leaders and were factionalised. Such a society was not easily open to renewal through fresh leaders and borrowed ideas. The article suggests that Lesotho need to come to terms with its political history and to come up with a cultural re-orientation away from traditionalism, rebellion and factionalism. URI: http://hdl.handle.net/10311/585 Files in this item: 1
Maundeni_AJPSIR_2010.pdf (137.1Kb) -
Molomo, M.G. (Made Plain Commucation, NaN, 2008)[more][less]
Abstract: This chapter discusses the national integrity system of political parties. In assessing the viability and integrity of political parties, the purpose of their existence needs to be established and analysed. The building and institutionalisation of political parties is a basic prerequisite for deepening and consolidating democracy. However, the organisational structures and the resources at the disposal of political parties influence their effectiveness. In addition, as entities that make national laws within the framework of parliamentary democracy, political parties must conduct themselves in an open and ethical manner. This chapter will assess their integrity, the handling of conflict of interest, and their perception regarding rules and disclosure. URI: http://hdl.handle.net/10311/635 Files in this item: 1
Molomo_TACB_2008.pdf (1.574Mb) -
Kamwendo, G. (Taylor & Francis, http://www.tandf.co.uk/journals, December NaN, 2010)[more][less]
Abstract: Finex Ndhlovu’s The politics of language and nation building in Zimbabwe is a product of his doctoral research project. The book, which is a welcome contribution to scholarly debates on nation building in multilingual and multicultural contexts, comprises seven chapters: Chapter one (Introduction), Chapter two (The history of language politics in Zimbabwe), Chapter three (The languages of Zimbabwe), Chapter four (Language and ethnicity in Zimbabwean polilitics), Chapter five (The politics of language: Nation building or empire building?), Chapter six (Language policy, hegemony and internal colonization) and Chapter seven (The Zimbabwean case study in global perspective). The book is supported by two informative appendices, i.e. Appendix A (list of interviewees arranged by category of participants) and Appendix B (guiding questions for oral interviews). URI: http://hdl.handle.net/10311/1050 Files in this item: 1
Kamwendo_LM_2010.pdf (281.0Kb) -
Meck, M.L.; Atlhopheng, J.; Masamba, W.R.L.; Ringrose, S. (Elsevier Science Ltd, http://www.elsevier.com/locate/pce, NaN, 2010)[more][less]
Abstract: The study set out to determine the weathering and dissolution of metal hosting minerals at Dorowa for purposes of deducing pollution potential to the nearby Save River. Phosphate rock is mined at Dorowa for the production of phosphate fertilizer. The major minerals found in the ring complex are feldspars, pyroxenes, apatite, magnetite and calcite. Chemical analysis established that the rocks are associated with metals that include copper, lead, zinc, cobalt, nickel, tin and cadmium. Among the many minerals present apatite and calcite host metals more than the other minerals due to their crystal structure. This study investigated the weathering and dissolution of these two minerals. Both apatite and calcite dissolve in natural environmental conditions prevalent at Dorowa. From the analysis the study concludes that the potential availability of metals trapped in the calcite and apatite structures is high. The understanding of weathering and dissolution of metal hosting minerals is important in predicting quality of water around the study area, because most villagers use the Save River as their primary drinking water source. URI: http://hdl.handle.net/10311/1021 Files in this item: 1
Atlhopheng_PCE_2010.pdf (758.1Kb) -
Meck, M.L.; Atlhopheng, J.; Masamba, W.R.L.; Ringrose, S. (Elsevier. http://www.elsevier.com, August 20, 2010)[more][less]
Abstract: The study set out to determine the weathering and dissolution of metal hosting minerals at Dorowa for purposes of deducing pollution potential to the nearby Save River. Phosphate rock is mined at Dorowa for the production of phosphate fertilizer. The major minerals found in the ring complex are feldspars, pyroxenes, apatite, magnetite and calcite. Chemical analysis established that the rocks are associated with metals that include copper, lead, zinc, cobalt, nickel, tin and cadmium. Among the many minerals present apatite and calcite host metals more than the other minerals due to their crystal structure. This study investigated the weathering and dissolution of these two minerals. Both apatite and calcite dissolve in natural environmental conditions prevalent at Dorowa. From the analysis the study concludes that the potential availability of metals trapped in the calcite and apatite structures is high. The understanding of weathering and dissolution of metal hosting minerals is important in predicting quality of water around the study area, because most villagers use the Save River as their primary drinking water source. URI: http://hdl.handle.net/10311/833 Files in this item: 1
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Gwebu, T.D. (Springer http://www.springerlink.com/index/3NU5AFH2F999FM9P.pdf -, NaN, 2003)[more][less]
Abstract: Based on government and other relevant documentation, this paper explores the conceptual linkage between population, development, and waste management in Botswana and the implications of this relationship for global climate change. Population is increasing, albeit at a decreasing rate. Spatially, the population is becoming more and more concentrated as the rates and level of urbanization increase. Economic growth has remained consistently high. The combined effect of population dynamics and economic development are having a noticeable imprint on the environment in the form of increased waste generation. Poor waste management poses a real threat to environmental sustainability in general and climate change in particular because of inadequate technology, weak institutional mechanisms to enforce regulations, and low levels of sensitization among the public to deal with the problem. Mitigation measures are suggested to minimize the negative effects of waste management on climate change. URI: http://hdl.handle.net/10311/478 Files in this item: 1
Gwebu_EM_2003.pdf (459.8Kb) -
Weiser, S. D.; Leiter, K.; Heisler, M.; McFarland, W.; Percy-de Korte, F.; DeMonner, S. M.; Tlou, S.; Phaladze, N.; Iacopino, V.; Bangsberg, D. R. (Public Library of Science, http://www.plos.org/, January 1, 2006)[more][less]
Abstract: Background In Botswana, an estimated 24% of adults ages 15–49 years are infected with HIV. While alcohol use is strongly associated with HIV infection in Africa, few population-based studies have characterized the association of alcohol use with specific high-risk sexual behaviors. Methods and Findings We conducted a cross-sectional, population-based study of 1,268 adults from five districts in Botswana using a stratified two-stage probability sample design. Multivariate logistic regression was used to assess correlates of heavy alcohol consumption (>14 drinks/week for women, and >21 drinks/week for men) as a dependent variable. We also assessed gender-specific associations between alcohol use as a primary independent variable (categorized as none, moderate, problem and heavy drinking) and several risky sex outcomes including: (a) having unprotected sex with a nonmonogamous partner; (b) having multiple sexual partners; and (c) paying for or selling sex in exchange for money or other resources. Criteria for heavy drinking were met by 31% of men and 17% of women. Adjusted correlates of heavy alcohol use included male gender, intergenerational relationships (age ≥gap 10 y), higher education, and living with a sexual partner. Among men, heavy alcohol use was associated with higher odds of all risky sex outcomes examined, including unprotected sex (AOR = 3.48; 95% confidence interval [CI], 1.65 to 7.32), multiple partners (AOR = 3.08; 95% CI, 1.95 to 4.87), and paying for sex (AOR = 3.65; 95% CI, 2.58 to 12.37). Similarly, among women, heavy alcohol consumption was associated with higher odds of unprotected sex (AOR = 3.28; 95% CI, 1.71 to 6.28), multiple partners (AOR = 3.05; 95% CI, 1.83 to 5.07), and selling sex (AOR = 8.50; 95% CI, 3.41 to 21.18). A dose-response relationship was seen between alcohol use and risky sexual behaviors, with moderate drinkers at lower risk than both problem and heavy drinkers. Conclusions Alcohol use is associated with multiple risks for HIV transmission among both men and women. The findings of this study underscore the need to integrate alcohol abuse and HIV prevention efforts in Botswana and elsewhere. URI: http://hdl.handle.net/10311/591 Files in this item: 1
Populaton based study.pdf (2.223Mb)