Showing papers by "Rivers State University of Science and Technology published in 1988"

Antibiotic resistance among coliforms and Pseudomonas spp. from bodies of water around Port Harcourt, Nigeria.

Abstract: Samples from municipal waste water, the Bonny River estuary and wells in and around Port Harcourt were examined for bacteriological quality over a 9 month period. A total of 157 Pseudomonas spp., 133 Escherichia coli and 282 other coliforms were isolated and tested for the incidence of resistance to 10 antibiotics. All of the Pseudomonas spp. were resistant to at least one of the antibiotics while 96.2% were resistant to two or more. Most (83.5%) of the E. coli and other coliforms (91.8%) were resistant to at least one antibiotic. All strains were susceptible to gentamicin. Minimal inhibitory concentrations of ampicillin and tetracycline for E. coli ranged from 6.25 to 50 and 6.25 to 12.5 micrograms/ml, respectively. Minimal inhibitory concentrations of ampicillin and tetracycline were 1000 and 25 micrograms/ml for the Pseudomonas strains. The high incidence of bacterial resistance to antibiotics is discussed in relation to the widespread use of antibiotics, and possible public health implications.

Preliminary observations on the effect of salinity on the reproduction and growth of freshwater Nile tilapia, Oreochromis niloticus (L.), cultured in brackishwater ponds

Abstract: . Tilapia, probably Africa's best candidate for aquaculture, is faced by the problems of small size due to overpopulation in culture systems. This paper reports the effect of high salinity on the reproduction of Oreochromis niloticus (L.) while testing the effect of a 20% protein supplemental feed on the growth and survival of this species in brackishwater ponds. The trial was run for 120 days in six 100-m2 ponds with fingerlings having an initial average weight of 2·80g. Salinity in the ponds rose from 25 ppt. to 50 ppt. during the culture period. Sampling for reproduction check was conducted every 2 weeks and 20% of the fish population were weighed to monitor growth changes and adjust quantity of feed fed. A 20% protein feed was fed at the rate of 5% and 3% of the total fish biomass during the first and second, and third and fourth months of the trial respectively. After 120 days the fish in each replicate were counted and weighed in bulk to obtain total weight while 50 females from each replicate were dissected and gonads examined. Results showed that growth was significantly different (P 0·05). 95% of the females were gravid but did not spawn. This suggests that gonadal development and onset of reproduction can be delayed by high salinities, which may be another practical method of population control in the culture of O. niloticus.

Incidence and biotyping of Aeromonas species from the environment.

Abstract: A survey was carried out to establish the incidence rate of Aeromonas species in various environmental samples with a view to ascertaining their reservoirs and distinguishing the biotypes. High rates of isolation were obtained from snails and water. This indicates that these samples are likely reservoirs and therefore constitute high sources of human infection. Low incidence rates were realised from poultry, cattle and humans, thus suggesting that these samples may be transient hosts. Two species of Aeromonas were isolated: A. sobria, and A. hydrophila which was further split into two biotypes, viz A. hydrophila subspecies hydrophila and A. hydrophila subspecies anaerogenes. All were involved with infections in humans.

Economic criteria in the choice of weed‐control methods for young pine (Pinus caribaea var. hundurensis Barr and Golf) plantations

Abstract: Summary: Resume: Zusammenfassung The effect of three types of cover crop Calapogonium mucunoides Desv., Centrosema pubescens Benth. and Pueraria phaseoloides (Rexb.) Benth., and hand-weeding on the growth and yield of Pinus caribaea var. hundurensis Barr and Golf were investigated after 42 months of planting. The costs and benefits of the four methods are evaluated and compared. Results show no significant differences in survival percentage, but show significant differences in mean height of trees after 15 months. Survival percentage, mean height, girth and basal area of trees, measured after 42 months, showed no significant difference between treatments. However, trees grown with C. mucunoides had the highest values of all four variables measured. Economic analysis shows that cost per hectare is higher for hand-weeding while cover cropping has a higher net present value of investment. The results demonstrate that cover cropping is a more profitable alternative to hand-weeding in weed control in pine plantations, and that C. mucunoides will be the best choice of the three cover crops studied. Criteres de choix economiques pour des methodes de desherbage des jeunes plantations de pins (Pinus caribaea var hundurensis Barr and Golf) Les effets de 3 sortes de couvert vegetal (Calapo-gonium mucunoides Desv., Centrosema pubescens Benth. et Pueraria phaseoloides (Rexb.) Benth. et du desherbage manuel sur la croissance et le rendement de Pinus caribaea var. hundurensis Barr et Golf ont eteetudies apres 42 mois de plantation. Les couts et profits des quatre methodes sont estimes et compares. Les resultats ne montrent pas de differences significatives dans le pourcentage de survie, mais en revanche les differences sont significatives sur la hauteur moyenne des arbres apres 15 mois. Le pourcentage de survie la hauteur moyenne, la surface basale et la circonference des arbres mesures apres 42 mois n'expriment pas de difference significative entre les traitements. Cependant, les arbres eleves avec C. mucunoides ont des valeurs plus elevees pour les quatre variables envisagees. L'analyse economique montre que le cout par hectare est plus eleve pour le desherbage, tandis que le couvert vegetal a une plus grande valeur nette d'investissement. Les resultats demontrent que le couvert vegetal est une alternative plus rentable que le desherbage manuel dans les plantations de pins et que C. mucunoides est le meilleur choix parmi les trois especes etudiees. L'analyse economique montre que le cout par hectare est plus eleve pour le desherbage manuel, tandis que le couvert vegetal a une plus grande valeur nette d'investissement. Les resultats demontrent que le couvert vegetal est une alternative plus rentable que le desherbage manuel dans les plantations de pins et que C. mucunoides est le meilleur choix parmi les 3 especes etudiees. Okonomische Kriterien fur die Unkrautbekampfung in Kulturen von Pinus caribaea var. hundurensis Barr & Golf Die Wirkung von Bodendeckern (Calapogonium mucunoides Desv., Centrosema pubescens Benth., Pueraria phaseoloides (Rexb.) Benth., und mechanischer Unkrautbekampfung (Jaten) auf das Wachstum und den Zuwachs von Pinus caribaea var. hundurensis Barr & Golfwurde 42 Monate nach der Pflanzung untersucht. Die Kosten und die Wirksamkeit der 4 Varianten wurden verglichen. Wahrend hinsichtlich des Anwachsens keine Unterschiede bestanden, ergaben sich fur die mittlere Wuchshohe der Baume nach 15 Monaten signifikante Unterschiede. Uberlebensrate, mittlere Hohe und Stammumfang waren 42 Monate nach der Pflanzung nicht significant verschieden, doch waren diese Parameter bei Calapogonium mucunoides am hochsten. Die Hektarkosten waren fur die mechanische Unkrautbekampfung hoher als fur die Bepflanzung mit Bodendeckern, die sich damit fur Kiefernkulturen als wirtschaftlicher erwies. Von den 3 Bodendeckern ist die erstgenannte Art vorzuziehen.

Insect pest spectrum of stored palm kernel and the damage caused by them.

Abstract: Assessment of damage to apparently good quality palm kernels by test insect species under laboratory conditions revealed that all the cultures had other pest species due to hidden infestation. The total damage caused by the insects to palm kernels in the experimental jars ranged from 17.5 to 30.9% at the end of a 1-yr storage period. With the exception of test species, Oryzaephilus mercator (Fauv.) and Tribolium castaneum (Herbst) which were predominant in cultures in which they were formally introduced, the other cultures were found to be dominated by O. mercator, T. castaneum, Lasioderma serricorne (F.) and Cryptolestes ferrugineus (Steph.). Thus the damage reported above was principally due to these four species. Symptoms of damage to palm kernels by O. mercator; T. castaneum and L. serricorne have been given for the first time and the pest status of the beetle pests associated with stored palm kernel assessed relative to damage caused.

Design of a Simple Gas and Solid Filtration Apparatus

Abstract: The results of experiments using needle-bonded polypropylene fibers as filter fabrics show that the air permeability of the filter fabrics depends on the type and size of needles used for fabric construction. For dust filtration, the internal structure of the filter fabrics has an effect on the resultant collection capacity based on the air permeability. A new gas and dust filtration apparatus was designed for the investigation, and the results obtained are reproducible. A regression analysis produced high correlations between pressure drop and air flow rates, which are statistically valid at a significance level of 0.1%.

Effect of ethane addition on propane pyrolysis

Abstract: Pyrolysis of propane/argon mixture in the presence of trace quantities (0.1% and 0.9%) of ethane was investigated at reflected shock wave temperatures between 1200 and 2000K. Traces of ethane accelerated propane decomposition at high temperature. However, increase in the quantity of ethane added to propane/argon mixture did not result in the same increase of its accelerating influence. Ethylene, methane and acetylene were the main hydrocarbon reaction products, with small quantities of propylene and ethane detected only at lower temperatures. Below 1500K, addition of ethane slightly enhanced the yields of ethylene and methane at the expense of propylene and ethane respectively. The selectivity for acetylene increased with increasing temperature and with the decline of those for the other products. For none of the products, did the presence of ethane alter the relationship between product formation rates and temperature. The influence of ethane addition on propane pyrolysis at high temperatures was explained in terms of increased radical concentrations, especially hydrogen atoms and vinyl radicals, formed at high conversions. These accounted for the rapid acceleration of propane decomposition and the high yield of acetylene at high temperatures.

Virulence factors from Aeromonas species.

Abstract: Isolates (116) of Aeromonas were obtained from various sources and subjected to tests to establish their virulence factors. A high number of the isolates (69.8%) were found to be enterotoxigenic. The isolates from snails had more enterotoxigenic strains (73.3%), while those from cattle faeces had the lowest (33.3%). Haemolysin production was found to be high (60.3%) amongst the isolates, and human isolates gave the highest number of haemolysin producing strains (70.6%), while the least number (33.3%) was obtained from cattle strains. About 50% of the strains produced both enterotoxin and haemolysin. The enzyme profile of the isolates included amylase, lecithinase, lipase and protease. There was no definite pattern in the elaboration of these enzymes and the production of haemolysin and enterotoxin, thus inferring that the production of these factors is not specific to the source. Two isolates were seen to produce none of these enzymes, and one was positive for enterotoxin and haemolysin production, leaving only one isolate which yielded none of these factors. The work adds more support to the pathogenicity of Aeromonas species, and indicates the existence of non-pathogenic strains.

Expository Teaching Styles of Nigerian Science Teachers. Part 1: The Science Teaching Observation Schedule

Abstract: As a preliminary to a study of the expository styles of science teachers (reported in Part IT) 54 biology, chemistry and integrated science lessons in Rivers State, Nigeria were analysed using the Science Teaching Observation Schedule. Forty‐two lessons were observed directly and the remainder analysed from transcripts. Four clusters emerged. It is shown that the presentation of factual information was unremitting throughout every lesson and that the clusters arise from variations in less frequent categories of interaction. Cluster 1 lessons (N= 13) involve little other than information giving. Cluster 2 lessons (N=21) include fairly extensive questioning of a factual and simple problem‐solving nature. Cluster 3 lessons (N= 9) include, in addition, a marked concentration on experimental procedures, not usually accompanied by practical activities. Cluster 4 (N=11), which persists when the analysis is reduced to a two cluster solution, is characterised by moderate levels of teachers' statements rel...

Numerical Simulation of Diffusion Rate of Crude Oil Particles into Wave Passes Water Regime

Abstract: Numerical models were developed to simulate the diffusion rate of crude oil particles in to wave passes water regime. developed models were used t o correlate the diffusion rate as a function of the physical properties of the crude oil sample, wave dimensions and diffusion coefficient. The models were simulated with the aid of Hewlett Packard HP-85 computer and found that the diffusion rate was principally influenced by the crude oil density and wave phase differences. The correlated models are useful in predicting extent of crude oil diffusion as a result of oil spillage.

Nigeria's 1980–1982 incomes policy — problems and issues

Abstract: Having reviewed Nigeria's recent attempts at incomes policy, it is concluded that future policies need to be kept to a one‐year maximum in order to generate sufficient public support to guarantee success Enforcement of incomes policies should also be guided strictly by the law, and guidelines should be vigorously pursued and upheld Whether this will be achieved, however, is rather less certain