Browsing Faculty of Science by Title
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Nkoanea, B.B.M.; Wibetoe, G.; Lund, W.; Abegaz, B. (South African Journal of Science, NaN, 2007)[more][less]
Abstract: BLEPHARIS ASPERA WAS COLLECTED FROM A copper–nickel mineralized area in Botswana and examined as a possible Cu–Ni indicator plant for biogeochemical prospecting. Different plant parts and the host soils were analysed using ultrasonic slurry sampling electrothermal atomic absorption spectrometry. All plant parts accumulated Cu and Ni in above-normal amounts, although not in hyperaccumulator concentrations. The leaf to soil Cu concentration ratio varied little with metal concentration in the soil. We propose Blepharis aspera as a Cu indicator plant. URI: http://hdl.handle.net/10311/282 Files in this item: 1
Examination of Blepharis.pdf (1.160Mb) -
King, J.G.; Garegae, M.; Ngwisanyi, T.H.; Ranganai, R. (Botswana Geoscientists Association, December NaN, 2005)[more][less]
Abstract: Fault-plane solutions of an earthquake can provide information about the type of fault. We report on the calculation of the fault-plane solutions of the earthquake that occurred on the morning of 18 May 2001 and was felt in the southern parts of Botswana and the North West Province of South Africa. The fact that there were few seismic stations in the vicinity of these areas meant that standard programs such as FOCMEC would produce a large number of possible fault-plane solutions. In this study a semi-manual method of determining fault-plane solution was utilized to obtain the most likely solution from a SEISAN program. The results obtained from these two methods shows that the focal mechanism for this earthquake was normal faulting. The two methods used compliment each other. Other information obtained includes epicenter at coordinates (longitude 26.0E, latitude 25.6S), magnitude of about 4.6 ML and origin time of 9:14.10.52 UTC. URI: http://hdl.handle.net/10311/337 Files in this item: 1
King_BJES_2005.pdf (143.0Kb) -
Mubyana-John, T.; Wutor, V.C.; Yeboah, S.O.; Ringrose, S. (Academic Journals. http://www.academicjournals.org/SRE, NaN, 2007)[more][less]
Abstract: The influence of wild fires on microbial community structure, soil organic matter, sulphur oxidising and nitrifying microbial populations in the floodplains of the Okavango Delta of Botswana was assessed. Microbial community structure was assessed by phospholipids ester-linked fatty acids (PLFA) quantification while microbial sulphur oxidisers were assessed by Most Probable Number (MPN). Community structure assessment showed that burning shifted the microbial community structure from single cellular bacteria being the dominant groups to filamentous fungi and actinomycetes being the most dominant groups. Generally burning increased the fungal component (18:2 w6) matrix from 3.40 to 8.35 while the actinomycetes and sulphur reducing bacterial (10 Me 16:0) component also increased from 1.02 to 1.70 mostly in the floodplains. Generally, the organic matter content declined with burning. However, the influence of burning on soil pH was non conclusive. Soil microbial biomass carbon increased slightly after the fire. The number of heterotrophic and nitrite-oxidizing and sulphur reducing bacteria increased. Overall, these results indicate that burning significantly alters the microbial community structure as large above ground losses of nutrients during and after burning often results in low quantities of nutrients released into the soil. URI: http://hdl.handle.net/10311/349 Files in this item: 1
Fire and.pdf (2.461Mb) -
Mutanyatta, J.; Bezabih, M.; Abegaz, B.; Dreyer, M.; Brun, R.; Kocher, N.; Bringmann, G (Elsevier Ltd.http://www.elsevier.com/wps/find/journaldescription.cws_home/942/description#description, NaN, 2005)[more][less]
Abstract: From the roots of Bulbine frutescens, the first sulfated phenylanthraquinones were isolated, together with their known sulfate-free analogs. Their structures were elucidated by spectroscopic and chiroptical methods, by acid hydrolysis or by partial synthesis. The new compounds have the usual stereo-orientation at the biaryl axis (i.e., with the acetyl portion above the anthraquinone plane) except for sodium ent-knipholone 60-O-sulfate (and thus, also its hydrolysis product, ent-knipholone), which exhibit an opposite axial configuration. We also describe the first stereoanalysis of natural phenylanthraquinones, some of which were found to be not enantiomerically pure, some even nearracemic. We furthermore, report on the first X-ray structure analysis of a phenylanthraquinone, viz. 40-O-demethylknipholone. URI: http://hdl.handle.net/10311/246 Files in this item: 2
license.txt (1.998Kb) -
Omari, K.; Mubyana, T.; Matsheka, M.I.; Bonyongo, M.C.; Veenendaal, E. (South African Journal of Botany http://www.elsevier.com/wps/find/journaldescription.cws_home/707238/description#description, NaN, 2004)[more][less]
Abstract: Effects of flooding on soil nitrogen (N), and asymbiotic nitrogen fixing bacterial (diazotroph) populations of the Okavango Delta were investigated. Diazotrophs from the rhizosphere of dominant annual and perennial grasses of the Okavango Delta were isolated on N-free composite media and identified applying morphological and biochemical criteria and Restriction Fragment Length Polymorphism (RFLP). Azotobacter species were found associated mostly with the grasses Andropogon guyanus and Vetevaria nigritiana (103CFU g–1 rhizosphere soil). Annual grasses such as Eragrostis inamoena, Setaria sphacelata as well as perennials showed insignificant populations (<101CFU g–1 soil). On the contrary, Azospirillum spp. was found associated with most of the grasses. Highest population densities (above 104MPN g–1 soil) were observed in rhizospheres of E. inamoena, Cympogon excavatus, Sporobolus acinifolis, Eragrostis lapila and Eragrostis rigidor and lowest population densities (below 102MPN g–1 soil) in rhizospheres of Andropogon guyanus and Panicum repens. Flooding increased the Azotobacter populations, while Azospirillum spp. populations were significantly reduced. Nitrogen-fixing sulphur reducers were observed in the rhizosphere of annuals (A. guyanus and P. repens) and only in perennials growing in flooded soils. No Beijerinckia species were found associated with any of the grasses. The highest soil nitrogen levels were detected in flooded soils (<0.20% N) while no N was detected in the rhizosphere soil of grasses growing in very dry soils (<5% moisture content). The results indicate that in the Okavango Delta, total soil nitrogen varies with flooding regime. With flooding, the diazotroph population shifts towards Azotobacter and Nfixing sulphur reducers while Azospirillum spp. are widespread in non-flooded soils. RFLP analysis of the 1 450bp amplicon using the restriction endonuclease Alu1, showed three different banding profiles, suggesting the occurrence of three different species of Azospirillum. URI: http://hdl.handle.net/10311/294 Files in this item: 1
Flooding and its influence.pdf (2.253Mb) -
Setshogo, M.P.; Mbereki, C.M. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: The sale of herbal medicine, either as concoctions or single plant specimens, has become common in the streets and main shopping centres of major towns and cities in Botswana. A study was undertaken to collect information on the uses of medicinal plants sold by street vendors in Gaborone, Botswana during June 2008 to December 2008. The indigenous knowledge of the street vendors and the plants used for medicinal purposes were collected through questionnaire and personal interviews during field trips. The survey showed that the street vendors used 47 species of plants distributed in 45 genera belonging to 29 families to treat various diseases and health conditions. The documented medicinal plants were mostly used to cure skin sores, sexually transmitted diseases (STD) and asthma. In this study, the most dominat families are the Asteraceae and Fabaceae, each with 5 species and roots were most frequently used for the treatment of diseases accounting for 62% of the medicines sold. This study showed that many people in Botswana still continue to depend on medicinal plants for primary healthcare. URI: http://hdl.handle.net/10311/922 Files in this item: 1
Setshogo_AJPSB_2011.pdf (876.4Kb) -
Mabbs, R.; Nijegorodov, N.; Downey, W.S. (Elsevier Science Ltd. www.elsevier.com/locate/saa, NaN, 2003)[more][less]
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Kwaambwa, H.M.; Maikorera, R. (Elsevier B.V. www.elsevier.com/locate/colsurfb, NaN, 2007)[more][less]
Abstract: The fluorescence studies of coagulating protein extracted from Moringa oleifera seeds have been studied using steady-state intrinsic fluorescence. The fluorescence spectra are dominated by tryptophan emission and the emission peak maximum ( max = 343±2 nm) indicated that the tryptophan residue is not located in the hydrophobic core of the protein. Changes in solution pH affected the protein conformation as indicated by changes in the tryptophan fluorescence above pH 9 whereas the ionic strength had minimal effect. The exposure and environments of the tryptophan residue were determined using collisional quenchers. URI: http://hdl.handle.net/10311/323 Files in this item: 1
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Gumbricht, T.; Wolski, P.; Frost, P.; McCarthy, T.S. (Elsevier http://www.doi:10.1016/j.jhydrol.2003.11.010, NaN, 2004)[more][less]
Abstract: The pristine Okavango Delta wetland of northern Botswana is potentially under threat due to water abstraction from its tributaries. We have developed a statistical model which makes it possible to predict the extent of wetland loss which will arise from water abstraction. The model also permits prediction of the maximum area of flooding, and its spatial distribution, three months in advance of the flood maximum. The model was calibrated using maximum areas of seasonal inundation extracted from satellite imagery covering the period 1985–2000, which were correlated with rainfall and total flood discharge. A technique was developed to translate the modelled flood area into a flood map. The methodology can predict maximum area of flooding and its distribution with better than 90% accuracy. An important, although relatively minor, source of error in the spatial distribution of the flood arises from a secular change in flood distribution in the distal Delta which has taken place over the last 15 years. Reconstruction of flooding history back to 1934 suggests that the Delta may be subject to a quasi 80 year climatic oscillation. If this oscillation continues, the extent of flooding will increase in the coming decades. URI: http://hdl.handle.net/10311/428 Files in this item: 1
Gumbricht_JH_2004.pdf (1.267Mb) -
Ddamba, W.A.A.; Ngila, J.C.; Mokoena, T.T.; Motlhagodi, K. (South African Journal of Chemistry. <http://ejour.sabinet.co.za/images/ejour/chem/chem_v55_a1.pdf>., NaN, 2002)[more][less]
Abstract: The copolymerization of difurylmethane with maleic anhydride in the presence of azobisisobutyronitrile as an initiator has been investigated at 65 °C, 72 °C and 85 °C in different solvents. Reaction feeds containing 85 mol % and higher of difurylmethane yielded a soluble alternating copolymer in which the furan residue entrained in the polymer chain formed 2,5 linkages and had 3,4 unsaturation. The 1:1 difurylmethane– maleic anhydride adduct was readily prepared, and at the above temperatures and in the presence of the radical initiator partially underwent retro-Diels–Alder reaction. Copolymerization of the difurylmethane and maleic anhydride thus formed yielded the unsaturated alternating copolymer. Copolymers prepared from reaction feeds with proportions of difurylmethane lower than 85 mol % had higher cross-link density and exhibited higher thermodecomposition temperatures. URI: http://hdl.handle.net/10311/305 Files in this item: 1
Free radical.pdf (2.417Mb) -
Bwire, R N; Majinda, R R; Masesane, I B; Steel, P G (International Union of Pure and Applied Chemistry. http://stage.iupac.org/publications/pac/, NaN, 2009)[more][less]
Abstract: The Diels–Alder adducts of ethyl (E)-3-nitroacrylate and furan provided a common and versatile template for the stereocontrolled synthesis of an isomer of the natural product oryzoxymycin and polyhydroxylated cyclohexyl β-amino acid derivatives. The strategy for the synthesis of the polyhydroxylated cyclic β-amino acid derivatives involved base-induced fragmentation of the oxanorbornene skeleton and face selective oxidation reactions. A Pd-catalyzed transfer hydrogenation reaction in the presence of organic acids is also described. This reaction is amenable to being enantioselective through use of optical pure chiral organic acids. URI: http://hdl.handle.net/10311/301 Files in this item: 1
From nature.pdf (2.826Mb) -
Mubyana-John, T.; Wright, M.G. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: A study assessing fungi isolated from three climatic regions of Botswana as a possible control for root knot nematodes (Meloidogyne spp.) affecting the tomato(Lycopersicon esculentum L. var. ‘Money maker’) crops was conducted. Out of 1,250 soil fungal isolates, only 232 soil fungi from the Okavango Delta, Bobirwa district and different saltpans in Botswana could be sub cultured, and screened for antagonism against Meloidogyne sp. Seven of the isolates i.e., Trichoderma sp., Penicillium sp., Dendriphiopsis sp., Fusarium chlamydosporium, Cochliobolus sativus, Aspergillus fumigatus and an unidentified sterile fungus showed potential to immobilize nematode juveniles on agar plates within 2-4 days. C. sativus and Dendriphiopsis sp. showed maximum paralysis on agar plates and eventually death of the Meloidgyne sp. juveniles. In greenhouse studies using tomato plants the fungi alleviated the effect of nematodes by increasing plant, shoot height and root weight as compared to the reference controls. Cochliobolus sativus and Trichoderma sp. showed maximum plant protection of tomato plants under greenhouse conditions. Fungi ability to produce cellulase and chitinase were some of the mechanisms studied. The results indicated that Trichoderma sp., Penicillium sp., Dendriphiopsis sp., Fusarium chlamydosporium, Cochliobolus sativus and Aspergillus fumigatus are nematode antagonistic fungi indigenous to Botswana that can be used to control nematodes as they are better adapted in comparison to introduced fungi. URI: http://hdl.handle.net/10311/917 Files in this item: 1
Mbuyana-John_AJPSB_2011.pdf (813.1Kb) -
Abegaz, B.M.; Bezabih, M.; Msuta, T.; Brun, R.; Menche, D.; Muhlbacher, J.; Bringmann, G. (American Chemical Society. http://pubs.acs.org/jnp/, NaN, 2002)[more][less]
Abstract: The novel phenylanthraquinones 4'-O-demethylknipholone-4'-O-β-D-glucopyranoside (2) and gaboroquinones A (3) and B (4) were isolated from the African medicinal plant Bulbine frutescens. Biaryl 2 represents the first phenylanthraquinone glucoside, while 3 and 4 are the first side-chain-hydroxylated phenylanthraquinones. Their constitutions were determined by spectroscopic analysis, in particular by HMBC, HMQC, and ROESY NMR investigations, and by chemical transformations. The axial configurations were elucidated chemically, by deglucosylation of 2 and by side-chain deoxygenation of 3 and 4 to give the known phenylanthraquinones 4'-O-demethylknipholone (5), isoknipholone (6), and knipholone (1), respectively, and chiroptically, by CD investigations. Compounds 2, 3, and 4 showed moderate to good antiplasmodial and antitrypanosomal activities in vitro. URI: http://hdl.handle.net/10311/346 Files in this item: 1
Gaboroquinones.pdf (407.3Kb) -
Motshegwe, S.M.; Holmback, J.; Yeboah, S.O. (AOCS Press. http://www.springerlink.com/content/0003-021X, NaN, 1998)[more][less]
Abstract: A preliminary investigation of the bulk properties of the oil from the edible mophane caterpillar (phane), Imbrasia belina, showed a significant difference in the iodine values of the oils from mature and young phane. Detailed analysis of the fatty acid composition of the two oil samples was thus carried out by capillary gas chromatography (GC) and complemented with 1H and 13C nuclear magnetic resonance (NMR) studies to investigate the degree of unstauration in the two oil samples. While these studies showed that the oil samples from the mature and young mophane caterpillar were much the same in fatty acid composition, the data revealed a significant divergence from a literature report on phane oil. This earlier report puts the ratio of total saturated to total unsaturated fatty acids at approximately 1:1 (48.2:48.8, in percentages) and estimates the fatty acid composition for the major fatty acids as 16:0 (31.9%), 18:0 (15.2%), 18:1 (20.4%), 18:2 (9.9%), and 18:3 (19%). The data collected from the present work, however, showed the fatty acid composition for total saturated and total unsaturated fatty acids to be 40.5 and 57.0%, respectively. This work estimated the fatty acid composition for the major fatty acids as 16:0 (27.2%), 18:0 (12.3%), 18:1 (16.1%), 18.2 (10.7%), and 18:3 (29.0%). Thus, linolenic acid was the most abundant fatty acid in the phane oil. The GC results of the present analysis were largely corroborated by studies of the composition of fatty acid classes in the phane oil estimated from integrals of 1H and 13C NMR signals. Oils from other edible Lepidoptera larvae are also known to be much richer in unsaturated than saturated fatty acids. URI: http://hdl.handle.net/10311/307 Files in this item: 1
General properties.pdf (1.906Mb) -
Cailteux, J.L.H.; Kampunzu, A.B.; Lerouge, C.; Kaputo, A.K.; Milesi, J.P. (Elsevier www.elsevier.com/locate/jafrearsci, NaN, 2005)[more][less]
Abstract: The Neoproterozoic central African Copperbelt is one of the greatest sediment-hosted stratiform Cu–Co provinces in the world, totalling 140 Mt copper and 6 Mt cobalt and including several world-class deposits (P10 Mt copper). The origin of Cu–Co mineralisation in this province remains speculative, with the debate centred around syngenetic–diagenetic and hydrothermal-diagenetic hypotheses. The regional distribution of metals indicates that most of the cobalt-rich copper deposits are hosted in dolomites and dolomitic shales forming allochthonous units exposed in Congo and known as Congolese facies of the Katangan sedimentary succession (average Co:Cu = 1:13). The highest Co:Cu ratio (up to 3:1) occurs in ore deposits located along the southern structural block of the Lufilian Arc. The predominantly siliciclastic Zambian facies, exposed in Zambia and in SE Congo, forms para-autochthonous sedimentary units hosting ore deposits characterized by lower a Co:Cu ratio (average 1:57). Transitional lithofacies in Zambia (e.g. Baluba, Mindola) and in Congo (e.g. Lubembe) indicate a gradual transition in the Katangan basin during the deposition of laterally correlative clastic and carbonate sedimentary rocks exposed in Zambia and in Congo, and are marked by Co:Cu ratios in the range 1:15. The main Cu–Co orebodies occur at the base of the Mines/Musoshi Subgroup, which is characterized by evaporitic intertidal–supratidal sedimentary rocks. All additional lenticular orebodies known in the upper part of the Mines/Musoshi Subgroup are hosted in similar sedimentary rocks, suggesting highly favourable conditions for the ore genesis in particular sedimentary environments. Prelithification sedimentary structures affecting disseminated sulphides indicate that metals were deposited before compaction and consolidation of the host sediment. The ore parageneses indicate several generations of sulphides marking syngenetic, early diagenetic and late diagenetic processes. Sulphur isotopic data on sulphides suggest the derivation of sulphur essentially from the bacterial reduction of seawater sulphates. The mineralizing brines were generated from sea water in sabkhas or hypersaline lagoons during the deposition of the host rocks. Changes of Eh–pH and salinity probably were critical for concentrating copper–cobalt and nickel mineralisation. Compressional tectonic and related metamorphic processes and supergene enrichment have played variable roles in the remobilisation and upgrading of the primary mineralisation. There is no evidence to support models assuming that metals originated from: (1) Katangan igneous rocks and related hydrothermal processes or; (2) leaching of red beds underlying the orebodies. The metal sources are pre-Katangan continental rocks, especially the Palaeoproterozoic low-grade porphyry copper deposits known in the Bangweulu block and subsidiary Cu–Co–Ni deposits/occurrences in the Archaean rocks of the Zimbabwe craton. These two sources contain low grade ore deposits portraying the peculiar metal association (Cu, Co, Ni, U, Cr, Au, Ag, PGE) recorded in the Katangan sediment-hosted ore deposits. Metals were transported into the basin dissolved in water. The stratiform deposits of Congo and Zambia display features indicating that syngenetic and early diagenetic processes controlled the formation of the Neoproterozoic Copperbelt of central Africa. URI: http://hdl.handle.net/10311/387 Files in this item: 1
Kampunzu2005GenesisSediment.pdf (2.837Mb) -
Ranganai, R.T.; Whaler, K.A.; Ebinger, C.J. (Elsevier Science Ltd. www.elsevier.com/locate/jafrearsci, NaN, 2008)[more][less]
Abstract: The granite-greenstone terrain of south-central Zimbabwe, encompassing the Belingwe (Mberengwa) greenstone belt and sections of the Great Dyke, provides important constraints on models for the evolution of the Zimbabwe craton and the Archaean crust in general. In this paper we enhance and model existing and recently acquired gravity data from the region and correlate the anomalies and their derivatives with the known basement geology to evaluate models for greenstone belt development. We also study the spatial gneiss-granite- greenstone association in general, and the geologic implications of models of the anomaly patterns in particular. Although the Belingwe greenstone belt has been mapped, its subsurface geometry is poorly known. Similarly, the Great Dyke is well studied, but no systematic study of the extent and cross-cutting relations of other mafic dykes in the Archaean crust has been undertaken. The regional gravity field shows no evidence for crustal thickness variations in the area and the gravity anomalies can be explained by lateral density variations of the supracrustal rocks. Prominent gravity highs are observed over the high density (≤ 3000 kg/m3) volcanosedimentary piles (greenstone belts) and ultramafic complexes. Well-defined elongate, sub-oval/elliptical gravity lows are associated with intrusive granitic plutons. The granite-greenstone contacts are marked by steep gravity gradients of up to 5 mGal/km that imply steeply dipping or near-vertical contacts for the anomalous bodies. This is tested and confirmed by 2½D modelling of gravity profiles across the Belingwe and Fort Rixon greenstone belts, constrained by measured densities and observed geological data. The modelling also indicates that these belts, and possibly all the belts in the study area (based on comparable densities and anomaly amplitudes), have limited depth extents in the range of 3–5 km. This is comparable to thicknesses obtained elsewhere from deep seismic reflection data and geoelectrical studies, but mapped stratigraphic thicknesses give a maximum depth extent of about 9.5 km. Present studies and previous work support the idea that the volcanics were extruded within rift zones and laid on older granitic crust, followed by subsidence and rapid deposition of sediments that were sourced from the adjacent basement terrains. The volcano-sedimentary sequences were subsequently deformed by intruding younger plutons and affected by late-stage strike-slip activity producing cross-cutting structures. URI: http://hdl.handle.net/10311/276 Files in this item: 1
Ranganai_JAES_2008.pdf (4.603Mb) -
Ranganai, R.T.; Kampunzu, A.B.; Atekwana, E.A.; Paya, B.K.; King, J.G.; Koosimile, D.I.; Stettler, E.H. (Royal Astronomical Society. http://www.wiley.com/bw/journal.asp?ref=0956-540X&site=1, NaN, 2002)[more][less]
Abstract: The Limpopo Belt of southern Africa is a Neoarchean orogenic belt located between two older Archean provinces, the Zimbabwe craton to the north and the Kaapvaal craton to the south. Previous studies considered the Limpopo Belt to be a linearly trending east-northeast belt with a width of ~250 km and ~600 km long. We provide evidence from gravity data constrained by seismic and geochronologic data suggesting that the Limpopo Belt is much larger than previously assumed and includes the Shashe Belt in Botswana, thus defining a southward convex orogenic arc sandwiched between the two cratons. The 2 Ga Magondi orogenic belt truncates the Limpopo–Shahse Belt to the west. The northern marginal, central and southern marginal tectonic zones define a single gravity anomaly on upward continued maps, indicating that they had the same exhumation history. This interpretation requires a tectonic model involving convergence between the Kaapvaal and Zimbabwe cratons during a Neoarchean orogeny that preserved the thick cratonic keel that has been imaged in tomographic models. URI: http://hdl.handle.net/10311/326 Files in this item: 1
Ranganai_GJI_2002.pdf (1.361Mb) -
Mbongwe, B.; Mmereki, B.T.; Magashula, A. (Elsevier Ltd. http://www.elsevier.com/wps/find/journaldescription.cws_home/404/description#description, March 12, 2007)[more][less]
Abstract: Healthcare waste management continues to present an array of challenges for developing countries, and Botswana is no exception. The possible impact of healthcare waste on public health and the environment has received a lot of attention such that Waste Management dedicated a special issue to the management of healthcare waste (Healthcare Wastes Management, 2005. Waste Management 25(6) 567-665). As the demand for more healthcare facilities increases, there is also an increase on waste generation from these facilities. This situation requires an organised system of healthcare waste management to curb public health risks as well as occupational hazards among healthcare workers as a result of poor waste management. This paper reviews current waste management practices at the healthcare facility level and proposes possible options for improvement in Botswana. URI: http://hdl.handle.net/10311/223 Files in this item: 2
license.txt (1.998Kb) -
Chaturvedi, P.; Pipedi-Tshekiso, M.; Moseki, B.; Kwape, P.E. (Academic Journals, http://www.academicjournals.org/SRE, NaN, 2011)[more][less]
Abstract: Bark of Bauhinia purpurea tree was collected and both the water and methanol extracts were prepared. Both extracts were tested for free radical scavenging activities and phenol content. Water extract was then tested for its protective potentials against alcohol induced toxicity. For this experiment, twenty rats were randomly divided into four groups, alcohol control group, normal control and two experimental groups. The rats in alcohol control group received alcohol (5 g/kg), rats in normal control were given water. Rats in two experimental groups were administered two doses of methanol extract (50 and 100 mg/kg respectively) plus alcohol (5 g/kg) for 30 days. At the end of the experiment, rats were killed after ether anesthesia. Liver and blood samples were collected for biochemical measurements. Parameters measured were thiobarbituric acid reactive substances, serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, reduced glutathione, glutathione peroxidase, superoxide dismutase, catalase and ascorbic acid. Results showed that both methanol and water extracts scavenged free radicals equivalent to gallic acid scavenging and were found rich in total phenol content. Results of in vivo experiments showed that the water extract inhibited lipid peroxidation, protected the experimental animals from hepatic toxicity and maintained the levels of antioxidants in dose dependent manner. URI: http://hdl.handle.net/10311/1018 Files in this item: 1
Chaturvedi_SRE_2011.pdf (207.7Kb) -
Ahmad, M.; Thangaraj, R.; Sathiaraj, T.S. (Springer, NaN, 2010)[more][less]
Abstract: Bulk samples of Sn10Sb20-xBixSe70 (0 B x B 8) chalcogenide alloys were prepared by the conventional melt quenching technique. Thin films were prepared on wellcleaned glass substrates by thermal evaporation technique. X-ray diffraction studies revealed that the alloys with x = 0 and 2 at.% of Bi were amorphous, whereas the alloys with x = 4, 6, 8 at.% were crystalline. The crystalline phases are identified as due to the formation of Bi2Se3 and BiSe2 phases. The microstructural and differential scanning calorimetric studies show the presence of these phases. A simple, straight forward procedure suggested by Swanepoel has been used to calculate the optical parameters, refractive index, and extinction coefficient. The optical gap for all the samples has been obtained from the Tauc plots. The variation in optical parameters for different Bi concentration has been explained on the basis of presence of defect states and the change in stoichiometry with the change in Bi concentration. Description: some symbols on the abstract may not appear as they are on the text. URI: http://hdl.handle.net/10311/752 Files in this item: 1
Heterogeneous crystallization.pdf (777.8Kb)