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Palynomorph assemblage biozonation of Paleogene strata in Bende–Umuahia Area,Niger Delta Basin, southeastern Nigeria

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Journal of Palaeogeography 2020年第2期9卷 168-180页

作者： okechukwu nicodem.s ikegwuonu Obianuju Patricia Umeji Osita Igwebuike Chiaghanam Kingsley KNwozor Otobong sunday Ndukwe Kingsley Chukwuebuka Chiadikobi Department of Geology Chukwuemeka Odumegwu Ojukwu UniversityUliNigeria Department of Geology University of NigeriaEnuguNigeria Department of Geology Federal UniversityOye-EkitiNigeria.

Cenozoic sediments form extensive outcrops in the Niger Delta Basin. Detailed palynostratigraphic study was undertaken across Paleogene sequences exposed in Bende–Umuahia Area in up-dip sectors of the Niger Delta Basin, southeastern Nigeria, to establish different palynomorphs assemblage zones, with their corresponding *** analysis was carried out on 27 selected outcrop samples, using the conventional maceration technique for recovering acid-insoluble organic-walled microfossils from sediments. Three Cenozoic lithostratigraphic units, including Imo Formation, Ameki Formation, and Ogwashi Formation, are exposed in the study area. Lithologies are sandstone, carbonaceous shale, mudstone, limestone, and the lignite. A total of 65 species of sporomorphs and 51 dinoflagellate cysts were identified. The recovered spores and pollen grains were used to establish six informal palynomorph assemblage zones, labeled as zone A – zone F, based on the first and the last occurrences of two or more species. These palynomorph assemblage zones include:(1) zone A — middle Paleocene scabratriporites simpliformis–Bombacidites annae zone;(2) zone B — late Paleocene Foveotricolporites crassiexinus–Mauritidiites crassiexinus zone;(3) zone C — early Eocene striatopollis catatumbus–Momipites africanus zone;(4) zone D — middle Eocene Margocolporites umuahiaensis–Gemmastephanocolporites brevicolpites zone;(5)zone E — late Eocene Cicatricosisporites dorogensis–Perfotricolpites nigerianus zone;and,(6) zone F — Oligocene–early Miocene Verrucatosporites usmensis–Magnastriatites howardii zone. The erected palynozones were correlated and compared with existing biozones in subsurface, down-dip sectors of the Niger Delta Basin, with pantropical palynological zones in tropical areas of Africa, and with palynofloral provinces of northern south America. A comparison of palynozones studied in southeastern Nigeria with other international palynozones, in this study, will assist in establishing

关键词： Palynology stratigraphy Biozonation spores and pollen grains Dinoflagellate cysts Cenozoic Niger Delta Basin

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Radiation Field Preference for Radiographic Anatomical Markers by Radiographers in a University Teaching Hospital in Nigeria

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Open Journal of Radiology 2014年第3期4卷 275-278页

作者： Thomas Adejoh sobechukwu Warric Iwene Onwuzu Flavious Bobuin Nkubli Nwamaka ikegwuonu Radiology Department Nnamdi Azikiwe University Teaching Hospital Nnewi Nigeria Medical Imaging Unit Department of Medical Centre University of Nigeria Nsukka Nigeria Department of Medical Radiography College of Medical Sciences University of Maiduguri Maiduguri Nigeria

Objective: The work aims to determine the radiographers’ preference between primary and secondary radiation fields for imprinting anatomical markers on radiographs. Methodology: Processed radiographs from the darkroom with evidence of radiographic anatomical markings were selected randomly and reviewed using a viewing box, within a 4-week period. The radiation field in which markers were placed was noted for each radiograph. Faintly-appearing and partly coned- off markers were excluded. simple statistical tools were used to derive central tendency. Result: 623 radiographs were assessed. 89.0% (n = 555) had markers in the primary radiation field while 11.0% (n = 68) were in the secondary radiation field. 98% (n = 611) of markers did not obstruct essential anatomy while 2% (n = 12) did, but the radiographs were neither repeated nor rejected because of the twin reason of reportability and the need to avoid additional radiation dose to patients. Conclusion: Radiographers in the centre preferred the primary radiation field for marker placement to avoid cone-off, cut-off and illegibility which leads to repeat. This, however, does not offer superior advantage to markers placed in secondary radiation field. It is recommended that marker placement preference should be guided by the need for legibility, aesthetics and avoidance of essential anatomy.

关键词： Marker Radiation Field Radiographs Radiographers

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Film-screen Radiographic Artefacts: A Paradigm shift in Classification

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Open Journal of Medical Imaging 2014年第3期4卷 108-111页

作者： T. Adejoh s. W. I. Onwuzu F. B. Nkubli N. C. ikegwuonu Medical Imaging Unit Department of Medical Centre University of Nigeria Nsukka Nigeria Medical Radiography Department University of Maiduguri Maiduguri Nigeria Radiology Department Nnamdi Azikiwe University Teaching Hospital Nnewi Nigeria

Objective: To propose a new method of classifying film-screen radiographic artefacts. Methodology: A prospective study was carried out at the Radiology Department of a University Teaching Hospital in Nigeria between June, 2011 and June 2013. Radiographs were assessed with the aid of a viewing box for artefacts which were arranged according to prior classifications by other researchers. They were subsequently grouped according to pre-arranged format into the new classification. Result: The following groups were observed: packaging (dark), procedure (greyscale), patient (greyscale), pre-processor (dark), processor (greyscale) and post-processor (greyscale). Conclusion: Classification of artefacts based on appearance and stage of introduction into film is easier to understand and remember.

关键词： Artefacts Greyscale Classification

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