African Journal of Science and Technology最新文献

{"title":"K-AR AGES, MINERALOGY, MAJOR AND TRACE ELEMENT GEOCHEMISTRY OF THE TERTIARY-QUATERNARY LAVAS FROM THE NDU VOLCANIC RIDGE N.W. CAMEROON","authors":"Ik Njilah, Hn Ajonina, K. Kamgang, M. Tchindjang","doi":"10.4314/AJST.V5I1.15318","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15318","url":null,"abstract":"The Ndu Volcanic Ridge occupies the central position amongst the continental sector volcanoes of the Cameroon Volcanic Line. K-Ar age determination coupled with field observations show that there were three episodes of volcanic manifestation: 31-28 Ma; 23-21 Ma and African Journal of Science and Technology Vol.5(1) 2004: 47-56","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83541158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IMPROVED COMBUSTION PROCESSES IN MEDICAL WASTES INCINERATORS FOR RURAL APPLICATIONS","authors":"C. Ketlogetswe, M. T. Oladiran, J. Foster","doi":"10.4314/AJST.V5I1.15320","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15320","url":null,"abstract":"The emergence of sustainable development programmes and the problem associated with continued steady increase in population have increased public awareness and concern for the environment. In particular, the demand for health services has increased to an extent that the health sector produces large quantities of biomedical wastes that can have severe impact on the environment if not properly disposed. Although incineration is not a clean process of disposing these wastes, it is still a preferred method especially when operated at elevated temperatures. The problem in developing countries is that several incinerators either in rural or urban areas operate at low temperatures and are therefore sources of environmental pollution. This paper describes the use of cost effective and appropriate pollution control systems to achieve acceptable combustion conditions. A small rig was designed for conducting tests on the incineration of rural clinical wastes in Botswana. Experimental results showed that if proper combustion conditions are applied to low technology rural clinical waste incinerators, the operating temperatures could increase from around 400 to above 850 o C. It was concluded that by increasing the operating temperatures of the current disposal methods and using wet scrubber in rural clinical waste incinerators, the combustion conditions could be improved significantly. African Journal of Science and Technology Vol.5(1) 2004: 67-72","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"97 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74887608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FLAVONOIDES ISOLES DES FEUILLES DE OCHNA AFZELII ET HEMISYNTHESE DES AFZELODINES A, B ET C A PARTIR DE LA DIHYDROLOPHIRONE C","authors":"My Bassomo, Dieudonné Emmanuel Pegnyemb, J. N. Mbing, D. Atchade, Raphael Ghogomu Tih, Bl Sondengarn, Alain Blond, Bernard Bodo","doi":"10.4314/AJST.V5I1.15324","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15324","url":null,"abstract":"L'etude phytochimique des feuilles de la plante medicinale camerounaise Ochna afzelii nous a permis d'isoler et de caracteriser neuf flavonoides parmi lesquelles la dihydrolophirone C 9. Le traitement de cette derniere avec une solution de KOH a 20 % a permis d'obtenir trois nouveaux biflavonoides : les afzelodines A 10, B 11 et C 12 a des rendements differents. African Journal of Science and Technology Vol.5(1) 2004: 101-108","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88364054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DETERMINATION OF VANADIUM IN FOODS BY ATOMIC ABSORPTION SPECTROMETRY","authors":"O. Awofolu","doi":"10.4314/AJST.V5I1.15314","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15314","url":null,"abstract":"This paper presents an assessment of the level of vanadium in foods (Plantain, Musa spp; Yam, Discorea rotundata; and Maize, Zea mays) from ten popular market places in Lagos metropolis, Nigeria. Total acid leaching digestion method was employed and determination was by Flame Atomic Absorption Spectrophotometry. The concentration of the metal obtained ranged from 0.01 ± 0.001 (M 3 ) - 0.62 ± 0.002 (M 2 ) for Musa spp; 0.02 ± 0.001 (M 3 , M 5 , M 9 ) - 0.41 ± 0.002 (M 3 ) for Discorea rotundata; and 0.01 ± 0.001 (M 1 ) - 0.35 ± 0.001 (M 6 ) for Zea mays. The overall mean concentrations of the metal were 0.19, 0.13 and 0.09mg g -1 in the same food order. The quality assurance of the analytical protocol was in the range of 91.5 - 98.1 % with C.V. of between 1.5 – 3.4%, which was adjudged acceptable for the analytical protocol. Vanadium was detected in all analysed foods with some elevated concentrations. Key Words: Vanadium, foods, AAS, coal, city, terminals African Journal of Science and Technology Vol.5(1) 2004: 15-21","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84661062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate Mapping: The First Step To Better Spatial Information Management By African Utilities","authors":"G. Mulaku","doi":"10.4314/AJST.V5I1.15316","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15316","url":null,"abstract":"African utilities, faced with the challenge of providing diverse services to some of the fastest growing urban areas in the world, have to improve their management systems, especially the management of their spatial information if they are to rise to this challenge. This paper argues that for this to happen, urgent revision and expansion of large scale base mapping, more investment in thematic mapping by the utilities themselves, plus greater commitment to digital management support systems such as Geographic Information Systems (GIS) are necessary. Reviews of the status of large scale mapping in Kenya's major towns and the level of map usage at Nairobi's major utilities are presented as examples to support this argument. African Journal of Science and Technology Vol.5(1) 2004: 29-33","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"69 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86423306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ACTIVITE POUZZOLANIQUE DES DECHETS DE BRIQUESET TUILES CUITES","authors":"U. Melo, Ndigui Billong","doi":"10.4314/AJST.V5I1.15323","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15323","url":null,"abstract":"RESUME:- Cette etude porte sur l'activite pouzzolanique des dechets de briques et tuiles cuites recoltes dans trois unites de production de Yaounde et ses environs. La caracterisation des materiaux (argiles lateritiques) bruts des dechets a montre qu'ils contiennent de l'argile kaolinitique peu plastique. Les dechets et ces argiles calcinees a 800 °C ecrases a O \u0000Mots cles: Dechets de briques et tuiles cuites, recuperation, clinker, pouzzolanes, pouzzolanicite, ciments, mortiers \u0000ABSTRACT:- The pozzolanic activity of waste fired bricks and tiles from three production units in and around Yaounde were studied. The raw materials (lateritic clays) of the wastes are kaolinitic and of low plasticity. The clays calcined at 800 °C and the wastes, crushed to fine powders of O Key Words: Fired bricks and tile wastes, wastes recycling, clinker, pozzolans, pozzolanicity, cements, mortars. African Journal of Science and Technology Vol.5(1) 2004: 92-100","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72932707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ASSESSMENT OF BUILDING FAILURES IN NIGERIA: LAGOS AND IBADAN CASE STUDY","authors":"G. Ayininuola, O. Olalusi","doi":"10.4314/AJST.V5I1.15321","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15321","url":null,"abstract":"The research focused on the causes and possible solutions to common buildings failures in Nigeria. Two major cities, Ibadan and Lagos were taken as case study. Questionnaires were administered to few selected architects, town planners, civil engineers and clients in the case study areas and also field trips were made to selected areas to ascertain common failures of buildings. Secondary data were obtained from the Nigerian Institute of Building (NIOB) and few media houses. The research outcome revealed that all parties in the building industry: Clients, Architects, Design Engineers, Local Authority (Town planners) and Contractors are contributing immensely to building failures in various dimensions. Also, the nation is loosing both human and material resources each time a building fails. Common failures seen on buildings were wall cracking, wall spalling, foundation settlement, column buckling, etc. Proper assurance of competent professionals and strict enforcement of ethical standards by the Nigerian Society of Engineers, the Nigerian Institute of Building, and the Nigerian Institute of Architects would reduce the problems identified to the minimum. African Journal of Science and Technology Vol.5(1) 2004: 73-78","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"94 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73802480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INVESTIGATION OF THE ANTIULCER PROPERTIES OF THE METHANOLIC LEAF FRACTION OF CISSAMPELOS MUCRONATA","authors":"S. Nwafor","doi":"10.4314/AJST.V5I1.15325","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15325","url":null,"abstract":"Fraction F1 containing alkaloids and sterols/triterpenes isolated from the methanolic leaf extract of Cissampelos mucronata A.Rich (Menispermaceae) was assayed for anti-ulcer activity using histamine- and stress-induced ulcer models. The fraction and crude methanolic extract (CME) were screened for anti-spasmodic activity using the spontaneously contracting smooth muscle of the rabbit jejunum. Their antimicrobial potency was assessed using different Gram-negative and Grampositive bacteria as well as two species of fungi. The result indicate that the fraction and CME exhibited 63.25 % and 57.26 % inhibition of ulcer induced by histamine while 57.15 % and 47.14 % inhibition were recorded against stress-induced ulcer respectively. The inhibitions of ulcer induction were significant (P Key Words: Cissampelos mucronata, fraction, histamine, stress African Journal of Science and Technology Vol.5(1) 2004:109-114","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74968658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DESIGN AND CONSTRUCTION OF A WATER HEATER CONTROLLER","authors":"Hm Taluder, Avinash K. Gholap, S. Kanyemba","doi":"10.4314/AJST.V5I1.15312","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15312","url":null,"abstract":"A micro-controller based water heater allows consumers to efficiently control domestic water heating system. Hardware and software designs and construction of the controller are done in the laboratory. The controller is interfaced with a real time digital watch, a temperature sensor and a keypad. In this design, a real time emulator driven by software controls a water heater using a micro-controller. Keywords. Micro-controller, geyser, keypad, interface, design, construction. African Journal of Science and Technology Vol.5(1) 2004: 1-5","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73620910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ESSAIS DE STABILISATION DE LA LATERITE AVEC LES FIBRES CELLULOSIQUES","authors":"Ab Bakam, M. K. Ndikontar, I. Njilah","doi":"10.4314/AJST.V5I1.15315","DOIUrl":"https://doi.org/10.4314/AJST.V5I1.15315","url":null,"abstract":"RESUME :- Afin de valoriser les matieres premieres locales, des blocs de laterite comprimee ont ete stabilises par des fibres cellulosiques provenant du Cyperus papyrus (cyperus), fibres longues et du Manihot esculenta (manioc), fibres courtes. Ainsi, la plus grande valeur de la resistance a la flexion statique a sec, 2,5 MPa, a ete obtenue avec des blocs de laterite comprimee stabilises a 5% de fibres longues. A cette meme teneur, les blocs de laterite contenant les fibres courtes donnent une resistance inferieure, soit 1,69 MPa. De facon inattendue, a 10% de fibres courtes, la resistance a la flexion a sec des briques (2,47 MPa) est superieure a celle des briques a fibres longues a teneur egale (2,08 MPa). La resistance a la flexion humide de tous ces blocs apparait nulle avec, cependant une conservation du reseau des blocs de laterite contenant les fibres cellulosiques du cyperus et du manioc a des teneurs superieures ou egales a 5%. Les briques absorbent l'eau de remontee capillaire en fonction de leur teneur en fibres cellulosiques et de la nature de ces dernieres. Pour les briques non stabilisees, le pourcentage d'eau absorbee est de 9,5%. A 7,5% de fibres longues, il n'est plus que 6,0%, alors qu'a 10% de fibres longues, il monte a 15,3% pendant que celui des fibres courtes atteint la valeur de 16,2% au bout d'une periode de 22 heures. \u0000Mot cles: laterite, briques stabilisees, fibres cellulosiques, resistance a la flexion, absorption par capillarite. ABSTRACT :- In order to give added value to local raw materials, compressed laterite bricks have been stabilised with cellulose fibres of Cyperus papyrus (cyperus), long fibres and Manihot esculenta (cassava), short fibres. The highest value of the dry flexural resistance, 2.53 MPa, was obtained with blocks stabilised at 5% long fibres content. At the same content the blocks of laterite containing short fibres gave a dry flexural resistance of 2.47 MPa which is higher than the value of 2.08 MPa for long fibres. The wet flexural resistance of all blocks is zero. But it can be noted that bricks containing cellulose fibres of cyperus and cassava at percentages higher or equal to 5% conserve their shape during complete immersion. The bricks absorbed water by capillarity depending on the nature and the percentage content of cellulose fibres. After a period of 22 hours, bricks containing 7.5% long fibres absorbed 6.0% water, less than 9.5% for unstabilised bricks; while at 10% of long fibres, absorption increased to 15.3%. In the same period, with 10% short fibres, the percentage water absorbed rose to 16.2%, indicating the better performance of the longer fibres. Key words : laterite, stabilised bricks, cellulose fibres, flexural resistance, absorption by capillarity. African Journal of Science and Technology Vol.5(1) 2004: 22-28","PeriodicalId":7641,"journal":{"name":"African Journal of Science and Technology","volume":"106 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80694051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}