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The relation of depositional patterns to hydrocarbon occurrence in middle to upper Miocene strata of part of the western Niger Delta Basin is postulated from the study of electrical logs, radiometric logs, lithologic logs, bottom ...
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The relation of depositional patterns to hydrocarbon occurrence in middle to upper Miocene strata of part of the western Niger Delta Basin is postulated from the study of electrical logs, radiometric logs, lithologic logs, bottom hole temperatures, intervals of hydrocarbon occurrence and paleontological data. Alternating sands and shales of the Agbada Formation were deposited in the area (up to 720 m, middle Miocene and 510 m, upper Miocene) mainly as regressive off lap sequences in a paralic environment with depo-centers located in the south of the study area. Three deltaic facies can be recognized based on the relative amounts of shale and sand including, proximal delta front facies (>70% sand), distal delta front facies (30-70% sand) and prodelta facies (<30% sand). The upper Miocene is generally sandier than the middle Miocene as a result of south-westerly progradation of delta front facies from middle to upper Miocene. Geo-thermal gradients in the area range from 2.5℃/100 m to 4.4℃/100 m. Isothermal maps show that some middle to upper Miocene shales could have undergone catagenesis to become mature source rocks. Three depositional zones (A, B, C) corresponding to dominant depositional facies i.e., proximal delta, distal delta and prodelta respectively, have been delineated from sand percentage maps. There is a progression of these zones from A through B to C in a generally south-westerly direction (the direction of delta progradation). Data for hydrocarbon intervals reveal the predominance of hydrocarbons in Zone C due to high entrapment potentials and to a lesser extent in Zone B. Zone A is barren as a result of poor entrapment potentials. The juxtaposition of distal delta front sands and prodelta mud could have initiated growth faults which constitute the major types of traps in the basin.
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The study focused on the assessment of household energy types, sources, uses and their implications on sustainable forest management in the Buea Municipality of the South West Region of Cameroon. The study was carried out in the m...
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The study focused on the assessment of household energy types, sources, uses and their implications on sustainable forest management in the Buea Municipality of the South West Region of Cameroon. The study was carried out in the mcnths of May- September 2005 and November-April 2006.The study made use of the random sampling technique for the administration of questionnaires. Along side the administration of the questionnaire, some selected Participatory rural Appraisal (PRA) tools were employed Results revealed that, Fuel wood (FW), Kerosene (K), Sawdust (SD), Cooking gas (CG). Charcoal (CH), Rubber (RB), Electricity (EL), were the main energy types/sources identified in the Buea Municipality Saw dust and Fuel wood were found to be the most frequently consumed energy type/source in the Buea Municipality with a resultant effect on deforestation. On an aggregate weighting, the area was found to consume a total of about 253m~3 of FW, 744Litres of K, 14602Kg of SD, 6360Litres of CG, 20625Kg of CH, 3861g of RB. and 40,299KW of EL in a month. Monthly total household expenditure on the various energy types/sources for the study area was evaluated at about 10496640 FRS CFA (US$ 20993). The quantity supplied and consumed of the identified energy types/sources were observed to be adversely affected by income levels of consumers, market prices for these energy types/sources, seasons and the disappearing forest.
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Rhipicephalus sanguineus ticks (n = 63) collected from five dogs (two adults and three puppies) housed in a kennel were screened for Ehrlichial agents (Ehrlichia canis, E. chaffeensis, and E. ewingii) using a species-specific mult...
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Rhipicephalus sanguineus ticks (n = 63) collected from five dogs (two adults and three puppies) housed in a kennel were screened for Ehrlichial agents (Ehrlichia canis, E. chaffeensis, and E. ewingii) using a species-specific multicolor real-time TaqMan PCR amplification of the disulphide bond formation protein (dsb) gene. Ehrlichia chaffeensis DNA was detected in 33 (56%) ticks, E. canis DNA was detected in four (6%) ticks, and one tick was coinfected. The E. chaffeensis and E. canis nucleotide sequences of the amplified dsb gene (374 bp) obtained from the Cameroonian R. sanguineus ticks were identical to the North American genotypes.
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Okundoperoxide (1) was isolated by bioassay-guided fractionation of extracts from Scleria striatinux (syn. S. striatonux). The compound contains a cyclic endoperoxide structural moiety and possesses moderate antimalarial activity.
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Okundoperoxide (1) was isolated by bioassay-guided fractionation of extracts from Scleria striatinux (syn. S. striatonux). The compound contains a cyclic endoperoxide structural moiety and possesses moderate antimalarial activity.
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Thirty eight drainage sediment samples collected from an area approximately 2050 km~2 west of Yaounde (Cameroon) have been evaluated for some heavy minerals of economic interest using granulometric, mineralogical and geochemical a...
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Thirty eight drainage sediment samples collected from an area approximately 2050 km~2 west of Yaounde (Cameroon) have been evaluated for some heavy minerals of economic interest using granulometric, mineralogical and geochemical analytical methods. Rutile was found in 10 samples, concentrated predominantly in the 2 mm-size fraction with quantities ranging from 0.3 to 6.8 wt%. Rutile exhibits irregular, prismatic and massive sub-rounded forms with oblong spheres dominating. Rutile also displays deep colours ranging from black to brown with a few red species (Titanium oxide (TiO2) content of 95.27 wt% and consists mostly of black and brown grains with a few red grains, found mostly within the northern portion of the study area. Garnet occurs in 33 samples predominantly within the 2 mm- and' 1 mm-sieve size fractions with quantities ranging from 0.03 to >58 wt%. The garnet grains are principally rounded and have colours of red, purple and brown with a white streak. The average major oxide content of the garnet is 39.77 wt% Fe_2O_3, 21.42 wt% Al_2O_3, and 22.88 wt% SiO_2, similar to almandine garnets. Kyanite occurs in 21 samples and is concentrated mostly within the 2 mm-sieve size fraction. The kyanite grains are sub-rounded, bladed, and elongated with blue colours and a characteristic white streak. The average composition of the kyanite is 58.04 wt% Al_2O_3 and 36.63 wt% SiO_2. The rutile, garnet and kyanite in the study area meet international specifications for economic ore and industrial minerals. The association of these heavy minerals (garnet and kyanite) in the same area (Yaounde series) implies that the rocks from which they were derived, crystallised during the eclogite faciès (T=750-800°C and P=1000-1200Kpa) possibly from pegmatite gneisses, micaschists, talcschists, granites and quartzites.
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Ti-doped zinc oxide and pure zinc oxide nanoparticles were synthesized by a modified oxalate route using Averrhoa carambola fruit juice as a natural source of oxalate. The characteristics of the precursors have been investigated b...
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Ti-doped zinc oxide and pure zinc oxide nanoparticles were synthesized by a modified oxalate route using Averrhoa carambola fruit juice as a natural source of oxalate. The characteristics of the precursors have been investigated by FTIR, TGA, and XRD.The results from the investigation revealed that the precursors are zinc oxalate and Ti-doped zinc oxalate which readily decompose at 450°C. The as-prepared precursors were calcined at 450°C for 4 hours, and the decomposition products have been characterized by XRD, SEM, EDX, and VSM. XRD results revealed crystallinity with hexagonal wurtzite structure, while the average grain size was found to be 26nm for Ti-doped ZnO and 29nm for ZnO, using calculations based on Debye-Scherrer equation. Furthermore, the morphological studies by SEM showed particle agglomeration, while the presence of Ti~(3+) in the zinc oxide lattice is indicated by EDS analysis. Finally the hysteresis loop from VSM results shows that Ti-doped ZnO exhibits ferromagnetism.
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Campanian-Maastrichtian marine sediments outcrop in five genetically linked sedimentary basins along the West African coast in the Gulf of Guinea, from the Douala Basin in Cameroon to the Anambra Basin in Nigeria. These sediments ...
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Campanian-Maastrichtian marine sediments outcrop in five genetically linked sedimentary basins along the West African coast in the Gulf of Guinea, from the Douala Basin in Cameroon to the Anambra Basin in Nigeria. These sediments in the more centrally located Rio del Rey Basin have been the least studied. Therefore, the geologic history of this region has merely been speculative. The Rio del Rey Basin like the adjacent Niger Delta is producing hydrocarbon from the offshore Tertiary sedimentary interval in which all studies have been focused, neglecting the onshore Cretaceous sediments. Outcrops in the basin are rare, small and highly weathered. Samples from some of these sediments have yielded a few Plank-tonic and dominantly benthonic foraminiferal assemblages. The long-ranging heterohelix and hedbergel-lids characterized the planktics while the species Afrobolivina afra which is a well known diagnostic taxon for Campanian-Maastrichtian sediments in West African basins clearly dominate the benthic assemblage. Its occurrence in association with other Upper Cretaceous forms such as Bolivina explicata, Praeb-ulimina exiqua, Gabonita lata, Ammobaculites coprolithiformis amongst others, formed the basis on which this age was assigned to the sediments sampled from the Rio del Rey Basin. Hence, this work has undoubtedly established the much needed link in this regional geologic history and correlates these sediments with the Logbaba and Nkporo Formations in the Douala Basin in Cameroon and the southeastern Nigerian Sedimentary Basins. Thus, these units were all deposited during this same geologic period and probably controlled by the same geologic event.
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The relation that exists between the structure of a compound and its function is an integral part of chemoinformatics. The similarity principle states that "structurally similar molecules tend to have similar properties and simila...
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The relation that exists between the structure of a compound and its function is an integral part of chemoinformatics. The similarity principle states that "structurally similar molecules tend to have similar properties and similar molecules exert similar biological activities". The similarity of the molecules can either be studied at the structure level or at the descriptor level (properties level). Generally, the objective of chemical similarity measures is to enhance prediction of the biological activities of molecules. In this article, an overview of various methods used to compare the similarity between metabolite structures has been provided, including two-dimensional (2D) and three-dimensional (3D) approaches. The focus has been on methods description; e.g. fingerprint-based similarity in which the molecules under study are first fragmented and their fingerprints are computed, 2D structural similarity by comparing the Tanimoto coefficients and Euclidean distances, as well as the use of physiochemical properties descriptor-based similarity methods. The similarity between molecules could also be measured by using data mining (clustering) techniques, e.g. by using virtual screening (VS)-based similarity methods. In this approach, the molecules with the desired descriptors or /and structures are screened from large databases. Lastly, SMILES-based chemical similarity search is an important method for studying the exact structure search, substructure search and also descriptor similarity. The use of a particular method depends upon the requirements of the researcher.
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A theoretical scheme for an experimental implementation involving bisolitonic matter waves from an attractive Bose-Einstein condensate, is considered within the framework of a non-perturbative approach to the associate Gross-Pitae...
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A theoretical scheme for an experimental implementation involving bisolitonic matter waves from an attractive Bose-Einstein condensate, is considered within the framework of a non-perturbative approach to the associate Gross-Pitaevskii equation. The model consists of a single condensate subjected to an expulsive harmonic potential creating a double-condensate structure, and a gravitational potential that induces atomic exchanges between the two overlapping post condensates. Using a non-isospectral scattering transform method, exact expressions for the bright-matter-wave bisolitons are found in terms of double-lump envelopes with the co-propagating pulses displaying more or less pronounced differences in their widths and tails depending on the mass of atoms composing the condensate.
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