FACULTY OF SCIENCE
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Item Units of burnside rings of cyclic groups(Faculty of Science, University of Ibadan, Nigeria, 1999) Alawode, M. A.Item Geophysical siting of boreholes in crystalline basement areas of Africa(Pergamon Press Ltd, 1992) Olayinka, A.I.This paper assesses the effectiveness of surface geophysical methods namely electrical resistivity, electromagnetic, seismic refraction, magnetic, gravity and induced polarization for groundwater exploration in crystalline basement complex areas. Most of these geophysical techniques can provide quantitative information on the characteristics of the weathered zone which relate to the occurrence of an economic aquifer. The critical factors in the choice of a particular method include the local geological setting, the initial and maintenance costs of the equipment, the speed of surveying, the manpower required as field crew, the degree of sophistication entailed in data processing to enable a geologically meaningful interpretation, and anomaly resolution. The particular advantages and limitations of each technique are highlighted. Several case histories from Nigeria and the rest of Africa indicate that electrical resistivity (both vertical sounding and horizontal profiling) is the most widely used, followed by electromagnetic traversing. These are often employed in combination to improve upon the percentage of successful boreholes. Due to the high cost of equipment, large scale of the field operations and difficulties in data interpretation, seismic refraction is not widely adopted in commercial- type surveys. Similarly, magnetic, gravity and induced polarization are used only sparinglyItem Error in depth determination from resistivity soundings due to non-identification of suppressed layers(Elsevier Science, 1997) Olayinka, A.I.The magnitude of errors in the determination of depth to bedrock from Wenner and Schlumberger resistivity sounding curves, caused by the nonidentification of a suppressed layer, has been investigated. The principal objective is to evaluate how the layer thicknesses and resistivities affect the accuracy of depth estimates. In the computations, the intermediate layer in a 3-layer model, in which the resistivity increases with depth, is removed and the 2-layer sounding curve that is electrically equivalent to the 3-layer curve is generated. The results indicate that there is a possibility for large depth underestimations when the resistivity contrast between layers 1 and 2 is very large. This is manifested in a steeply rising terminal branch on the sounding curve. There is a slight decrease in the depth underestimation as the resistivity contrast between layers 2 and 3 increases. Conversely, if the intermediate layer is fairly thick and the resistivity contrasts are not too large, the best-fit 2-layer curve shows large deviations from the 3-layer curve, in such cases, the intermediate layer can be identified, resulting in reliable depth estimates. A field example from Nigeria is presented in which the sounding data has been interpreted so as to account for a prebasement layer of intermediate resistivity, indicative of a fractured granite.Item Electromagnetic profiling for groundwater in precambrian basement complex areas of Nigeria(1990) Olayinka, A.I.Ground electromagnetic profiling, using a Geonics EM34-3 instrument, has been employed to identify areas of high conductivity in a Precambrian basement complex terrain of Nigeria. Field examples, conducted as part of a rural water supply programme, are presented. They indicate that the apparent conductivities are generally lower than about 60 mmho m-1. Subsequent borehole drilling suggests a good correlation between high EM34 anomalies, deep weathering and high well yield (> 1 1 s-1). On the other hand, boreholes sited on conductivity lows penetrated a thinner regolith with relatively lower yields.Item Electromagnetic profiling and resistivity soundings in groundwater investigation near Egbeda- kabba, Kwara state(1990) Olayinka, A.I.As part of a borehole siting programme for rural water supply in a Precambrian crystalline basement terrain, 36 Offset - Wenner electrical soundings and about 4.5 line-kilometres of ground conductivity profiling with a Gconics EM34-3 equipment were made near Egbeda-Kabba. Kwara Slate, Nigeria. The EM34-3 measurements provided a rapid reconnaissance tool in identifying high conductivity anomalies thought to be due to deep weathering and/or bedrock fissuring. The apparent conductivities arc generally less than 50 mmho m'1. A quantitative interpretation of the vertical sounding data indicated that the resistivity of the weathered zone varies over a wide range, from about 10 to 200 ohm.m, and that the overburden is generally less than 40m thick. Three abstraction wells, each having a yield of about 11s"1, were drilled at deeply weathered sites (depth to bedrock > 20m) identified from the surface geophysical measurements.Item BIOSYSTEMATIC STUDIES IN SOME NIGERIAN SPECIES OF ANTHERICUM LIN. AND CHLOROPHYTUM KER-GAWL. (LILIACEAE)(1981-03) ADEYEMI, F. A.Field surveys and investigations of representatives of Anthericum L. and Chiprophytum Ker-Gawl. complex in Nigeria were carried out in their natural habitats in at least sixteen States of the Nigerian Federation. All herbarium specimens in the Forestry Research Institute, Ibadan and in nine Nigerian Univetfsities visited were examined (if any). So far, ten species of Anthericum and fifteen species of Chlorophytum have been reported and collected in Nigeria. They were all studied morphologically. Detailed ecological analyses including the Chemical composition of their soils were carried out on three taxa of Anthericum and ten taxa of Chrolophytum. Many living populations were sampled from their different natural habitats in Nigeria, Their representatives were cultivated in three locations for experimental studies. Data were collected on the morphology by conventional methods and analysed. Anatomical data were amassed from the leaf surface patterns and the roots. Types of leaf margin anatomy were noted. Cytological studies were carried out in five taxa of Anthericum and eleven taxa of Chlorophytum. There were inter-generic hybridization tests. The use of lea f vein spacing interval and anther: filament ratio as taxonomic criteria have been suggested and their usefulness in the monocotyledon taxonomy, especially in Liliaceae, needed to be further explored. The importance of leaf margin anatomy as a taxonomic criterion above species level was highlighted. Chromosome counts for seven taxa were confirmed, viz; C. macrophvllum (A. Rieh.) Aschers 2n = 28. C. blepharophvllum gchwinf. ex Bak. 2n = 28. C. atenopetalum I Bak. 2n = 14. C. atenopetalum II (sp. nov.) 2n = 14. C. laxum R. Br. 2n = 14. C. inomatum Ker-Gawl. 2n = 14. C. togoense Engl. 2n = 14. New chromosome counts were recorded in :- C. geophilum Peter ex. v. Poelln. 2n = 28. C. alisaifolium Bak. 2n = 16. Chiprophytum X ( related to C. elatum ) 2n = 16. C . caulescens (Bak.) Marais & Reilly ( formerly A. caulescens Bak.) 2n = 16. A. Limosum Bak. 2n = 16. A. pterooaulon I Welw. ex Bak 2n = 24. A. Pterocaulon II 2n = 16. A. nubicum Bak. 2n = 16. A. pubirhachis Bak. 2n = 16. A. uvuiense 2n = 16. The possible evolution o f chromosome numbers in the complex has been postulated. The possible chromosome evolution o f the complex based on the available data from this work and existing literature has been proposed. Evidence was adduced to Support the Suggestion that the possible basic Chromosome number in the complex was x = 4, and that n = 8 Was a secondary basic number. It has also been contended that n =7 and n= 6 evolved from a more primitive n = 8. Supplementary evidence in Support of Marais and Reilly’ s (1978) transfer of A. caulescens from Anthericum into Chloronhytum as C. caulescens was adduced. A form of C.stenopetalum has been elevated to species level on account of its morphological, cytological and genetic differences. A new taxonomic key has been proposed for the Separation of Anthericum and Chiprophytum. The possible mode of evolution of some Nigerian species of Anthericum and Chlorophytum. based mainly on their leaf surface patterns, has been proposed.Item SPIN COMPLEXES IN FERROMAGNETISM(1988-11) AGBOOLA, A. I.The spin-wave theory in Heisenberg model of ferromagnetism is investigated with the Holstein - Primakoff transformation and with emphasis on the spin wave interactions. The temperature Tₒ below which the concept of magnons is valid is determined. By a special expansion formalism of operator (l-a+a/2S)1/2 which yields 1+(1-(1-1/2S)1/2 )a+a it is shown that quantized spin waves which behave like spin 1 quasiparticles (with dispersion relation ω~ k2 ) called magnons at temperatures T < Tₒ, are Bosons with an effective (negative) electrochemical potential µ that varies as T in the wave-wave interaction approximation. The various coefficients of Tv in the expression of the spontaneous magnetization M(T)/M(o) = l-(C1T3/2+C2T5/2+C3T7/2+C4T4) as well as the specific heat for some ferromagnets are calculated. The results are remarkably close to the experimental values obtained by other investigators. The method used enables one to deal especially with regimes of small spin values S for which µ differs substantially from zero. The influence of the chemical potential on some thermodynamic quantities are found for ferromagnets with Hexagonal-close-packed structures, as well as for cubic crystals, The existence of the spin wave interactions and hence of non-zero effective chemical potential is shown to give rise to a lowering of the thermodynamic internal energy with the implication that spin waves, on the average, form bound states called spin complexes. The kinematical as well as the dynamical interactions on the thermodynamic quantities are also found for some ferromagnets, by subjecting the magnons to intermediate statistics. The influence of the spin-wave-spin-wave-spin-wave interactions on the coefficients of Tv in the expression of the spontaneous magnetization of some ferromagnets are found to be negligible in comparison with wave-wave interactions. An attempt is made to extend the above calculations to spin complexes in antiferromagnetism, a phenomenon which seems to be relevant to high temperature superconductivity.Item MICROBIOLOGICAL STUDIES OF GUINEA CORN FERMENTATION FOR OGI-BABA PRODUCTION(1986-01) ADEYELE, S.Item Effect of ultraviolet radiation on survival, infectivity and maturation of schistosoma mansonicer cariae(Australian Society for Parasitology, 1990) Ariyo, A. A.; Oyerinde, J. P. O.S. mansoni cercariae exposed to ultraviolet radiation for 1,3, 5,10 and 20 s as well as non-irradiated cercariae remained actively motile 30 min post-irradiation. Thereafter the activity decreased with increasing dose level of radiation and age of cercariae. There was no significant difference between the rates of attachment of the batches of cercariae. The recovery rates (0-49% of cercariae to which mice were exposed) of adult worms were, however, significantly different from the number of cercariae calculated to have attached to the mice (93.5-100% of cercariae to which mice were exposed). Maturation and penetration rates were dependent on radiation exposure levels. Numbers of eggs deposited in the liver of mice as well as hatchability rate of eggs varied significantly with the levels of exposure to radiationItem An evaluation of the prevalence and intensity of liver fluke infection in cattle slaughtered in Jos abattoir with comments on the incidence of amphistome infection(1986) Okwuosu, V. N.; Ariyo, S. A.An evaluation of the prevalence of liver fluke disease of cattle revealed an upward trend for an urban abattoir. A total of 3072 animal gall bladders were assayed between December 1980 and January 1982 and 74.06 + 6.46% were positive, the major fluke species were Fasciola gigantic and diocrocoellum hospes with a few case of schistosoma bovis. The max/min. monthly prevalence rates were 85.42% and 60.00% respectively. The mean rates for D. hospes and F. gigantic were 57.95 + 6.58% nd 48.71 + 11.66% respectively. T-test assessments showed these mean to be significantly different. The study further showed that for natural infections of cattle mixed infections were more frequent than singe infections. The mean value were 32.13% as against X single infection rates of 25.5% and 16.45% for D. hospes and F. gigantic. Chi-square analysis confirmed that mixed infection rates were significantly higher than single infections for both species. The flike species were highly prolific, producing mac egg count of 50 x 103 and 60 x 103 c.p.ml for F. gigantic and D. hospes respectively. There was variation in egg count due to seasons with significantly more eggs produced in the dry than in the wet season, for freely infected animals, there wa suppression of egg production in mixed infections which though affecting the species, had more effect on F gigantic, this resulted in significantly more eggs being produces by either species in single than in mixed infections