nigerian defence academy
journal of science and engineering (ajse)
AN ANALYSIS OF THE ANTENNAE OF THE PARASITOID MELITTOBIA ACASTA (HYMENOPTERA: EULOPHIDAE)
N.G. Imandeh*, P.E. King, M.R. Fordy and M.J.W.
Using methods such as Scanning electron microscopy and behavioural observations, the antennae of an arrhenotokous eulophid, Melitoobia acasta Walker was studied in detail, in order to situate their role in the courtship behavior and the assessment and utilisation of hosts by the parasitoid.
Results revealed that the antennae have both mechanoreceptors and chemoreceptors such as trichoid sensilla, basiconic capitates pegs and multiporous plate sensilla (Type I and II).
The findings are discussed in relation to the behavior of the parasitoid as earlier reported.
PRELIMINARY INVESTIGATIONS ON THE
THERAPEUTIC ACTIVITIES OF DIMINAZENE AND
ISOMETAMIDIUM ON A TRYPANOSOMA
CONGOLENSE ISOLATE FROM THE KAURA ENDEMIC FOCUS OF BOVINE TRYPANOSOMOSIS
The therapeutic responses of a Trypanosoma congolense isolate obtained from the bovine trypanosomosis endemic focus of Kaura Local Government Area (LGA), to diminazene aceturate and isometamidium chloride were preliminarily investigated. Three goads infected with this trypanosome isolate were completely cured within 24 hours of isometamidium treatment, and remained trypanosomosis-free until the study was concluded 10 weeks later. However, there was relapsed infection in one of the two infected goats 17 days after diminazene aceturate treatment cleared the initial parasitaemia within 24 hours. Inspite of the clearance of the I. congolense parasitaemia in the cured animals by theses trypanocides, the declining trend in the values of the clinical parameters observed from the onset of the infection never reversed to normal values even during the 10 weeks post treatment monitoring. Isometamidium chloride at a dosage of 0.5mg/kg body wieht cleared the relapsed infections initially treated with diminazene. The continuous decline in clinical parameters in treatment aparasitaemic goatsin this study could be attributed to the cytotoxic effects of I. congolense derived substances or/and the effects of confinement of these experimental animals which were used to grazing for long distances in their natural habitats. The initial treatment of trypanosomosis positive cases with the cheap diminazene followed by isometamidium treatment of relapsed cases and vector trapping are suggested for effective control of bovine trypanosomosis in Kaura LGA.
CHARACTERISTICS OF THE SEEDS OF
DACTYLOCTENIUM AEGYPTIUM (l) P. BEAUV IN KADUNA,
GABRIEL A. AJIBADE, SULEIMAN D. ABDUL and
TAJUDEEN O OSENI
The external structure, weight and water content of Dactyloctenium seeds were investigated for variation among inflorescence morphotypes. Seed external structure was monomorphic in all morphotypes, with the caryopsis possessing external ridgs and the embryo enclosed in a translucent aleurone. There was insignificant correlation of the seed weight (r = - 0.15) and water content (r = 0.19) to the inflorescence morphotype, thus confirming that the morphotypes produce seeds tht have identical characteristics.
QUANTITATIVE ESTIMATES AND THE
INTERRELATIONSHIP OF SOME BIOCHEMICAL
CONSTITUENTS IN CAPSICUM ANNUUM L.
VARIETIES FROM SOUTH EASTERN NIGERIA
CHEUKWUMA S.I. ODOEMENA & KINGSLEY E. AKPABIO
Quantitative estimation of carotenoid, capsaicin and ascorbic acid contents and their interrelationship with each other were evaluated in seven varieties of Captsicum annuum. The highest carotenoid content was in N-LRP variety which also recorded the least capsaicin concentration. The N-YAP showed the highest value in capsaicin and ascorbic acid amounts than all the other varieties but least in carotenoid level. Ascorbic acid content was not significantly (P<0.5) correlated with that of capsaicin in all the varieties while the carotenoid level gave a negative linear correlation with the capsaicin level, indicating an increase rate of 58%. In conclusion the study has revealed that the higher the carotenoid content in Capsicum peppers the lower the capsicin and the pungency levels. PHOTOBIOLOGICAL EFFECTS OF ULTRAVIOLET
LIGHT ON SELECTED PATHOGENS
FOR DECONTAMINATION PURPOSES
WILLIAMS S. DONIYA
Comparative studies on the effects of ultraviolet light (UV) radiation on selected microorganisms was carried out with a view to using it for disinfection purposes. The test organisms were Escherichia coli, Staphylococcus aureus, Aspergillus niger and Penicillium notatum. The effect of UV lioght at 365 nm on the organisms was observed in their growth rate pattern at various time of exposure. The organisms vary considerably in their responses. E. Coli was the most susceptible, with its cells been killed after 45 minutes of exposure, while P. notatum wass the most resistant requiring the highest lethal time of 90 minutes.
THE EFFECTS OF BALANITES AEGYPTIACA
AND KIGELIA AGRICANA ON SURVIVAL OF PLANORBID SNAIL
BIOMPHALARIA PFEIFFERI, CHRONOMID AND
Acute concentration of reeze dried water extracts of Balanites aegyptiana and Kigelia Africana were exposed to planorbid snail, Biomphalaria pfeifferi, chironomid and mosquito larvae for 96 hours to determine the 96 hLC 50 values of these extracts for the organisms. The mortality percentages at the end of the 96 hours were calculated.
The 96 hLC 50 values of B. aegyptiaca and K. Africana were 5.0118 mgl-1 and 2.0417 mgl-1 respectively. For both extracts, a linear relationship between probit mortality of the snail and the logarithmic concentration of the extracts existed. There was no mkortality recorded with chironomid and mosquito larvae at the end of the 96 hours. The control experiments recorded no mortality. Behavioural patterns such as increased feacal droppings, sinking to the bottom and retraction were observed with the snail indicating stress. The mosquito larvae metamorphosed to the adult stage indicating no stress condition. K. Africana turned out to be more potent. The lethal doses of the water extracts of K. africana and Bu. aegyptiaca could be used as molluscicides in ponds without elimination of the chironomid and mosquito larvae, depending on the fist being cultivated.
MULTILAYER DEPOSITION OF COLLOIDAL
SUSPENSION UNDER THE INFLUENCE
OF MAGNETIC FIELDS
M.F. HAQUE and O.W. OLASOJI
ABSTRACTThe paper presents the results of an experimental and theoretical study of multilayer deposition of a colloidal suspension in a packed column technique. Experimentally, the deposition of submicron hematite particles (rp = 0.041 x 10-6m on C1018 steel bead (rb = 33.4 x 10-6m) was studied under the influence of magnetic fields. Theoretically, a model is proposed to describe the multilayer deposition phenomena, along with the lines of the existing monolayer deposition theories. The proposed model introduces one new parameter wich characterizes the multilayer deposition probability.
SOME PECULIARITIES OF CERTAIN CLASS OF
LINEAR DEGENERATE DIFFERENTIAL EQUATIONS
Consider the differential equation A dx + Bx = f(t), where, A and B are matrices and
x, dx and f(t) – vector functions. An equation of this kind is called a degenerate
differential equation. By comparison with the classical equation dx + Tx = f(t), the
degenerate differential equation has certain peculiar properties. In this study, some of these peculiarities are established.
SOME HEAVY METALS CONCENTRATION IN RAIN
WATER RUN-OFF ON PAVED ROADS IN LAGOS AND
ILORIN CITIES, NIGERIA
F.A. ADEKOLA*, O.A.A.
ELETTA & S.A. ATANDA
The concentrations of zinc, lead and iron in rainwater run-off on-paved roads in Ilorin and Lagos cities of Nigeria were determined using Atomic-Absorption spectrophotometric (AAS) technique.
All the heavy metals exhibited relatively high levels in the urban run-offs from these cities. Iron has the highest mean concentration while cadmium has the lower level. Although the levels of the heavy metals appeared to be relatively higher in Lagos than in Ilorin, there is however no significant difference in the mean concentration of each metal in both cities except for zinc. The mean concentration of zinc was significantly higher in Ilorin than in Lagos (P= 0.05).
The analytical results also indicate a strong correlation (r= 0.9597) between lead and cadmium in Ilorin run-off and between cadmium and zinc (r – 0.9661) in Lagos run-ff at 95% probability level. This suggests a most probable common source for Cd and Pb in Ilorin. It therefore appears that other sources different from automobile emissions might account for Pb and Cd levels in Lagos unlike in Ilorin for which the Pb and Cd might likely originate mainly from automobile emissions.
AN ANALYSIS OF THE ONE-DIMEMSIONAL
ELECTRONIC STRUCTURE OF VERY THIN
The Kronig-Penney model is adapted to analyze the electronic structure of very thin heterostructures. The variation of the barrier potential, Vo, with well widths dw for different values of the “strength of the binding” parameter, PH , is discussed; and “virture lowering” of the barrier potential, ……, which is a measure of the ……………eveling g probability of the carriers through the bearer, is identified and a lowering constant k…. = 2.78 x 10-3N is defined. The ratio ……Eg/…….PSL for any given dw exhibits two different constant values, with the change in the values occurring when PH = 1, or when mw dw dB Vo = ….2. A facor of ½, which may represent the spacing ratio of the charge for a uniform atomic spacing, was required in the ratio of the mass of the heaving holes to the mass of light holes for numerical fit.
NATURE OF SUSPENDED SEDIMENT TRANSPORT
INAN URBANIZED TROPICAL STREAM,
ISHAKU I. YARI MALLO
The gulp method was used to collect turbid river water samples in
an urbanized tropical steam in Kaduna metropolis,
northern Nigeria. The gravimetric method was used to
analyse the samples in the laboratory. Results shows
that the 30 randomlyselected samples from five
rainstorm events within a six-month rainy season,
yielded a mean suspended sediment transport of
1,556.9mg/l. Graphs relating the amount of suspended
sediment to both stage and discharge produced a
system of hysteric loops. This may be attributed to
occasional collapse of soil at the stream and gully
banks, direct dumping of debris into stream and
drains, and readily available weathered debris from
urban construction sites.
FABRICATIONAND ELECTRICAL STUDY OF
METAL-SEMICONDUCTOR, (Pb/Cu/Cu2O), DIODES
MUHAMMAD YUSUF ONIMISI & A.O. MUSA
This paper deals with metal-semiconductor diodes and involves the fabrication and study of electrical properties of Pb/Cu/Cu2O diodes prepared by partial thermal oxidation of copper at 9500C. The diode, apart from its simplicity of preparation and mechanical stability, forms a natural junction, Cu2/Cu which allows for improvement of the barrier height to give optimum rectifying properties. It is important to note that temperature and time played very important roles in the oxidation processes. The oxidation temperature was found to be proportional to the amount of copper(1) oxide layer deposited on copper.
To enhance the performance of the diode, the number of basic structure, Cu2O/Cu, was increased from one to two. The two sets of Cu2O were joined together through a lead foil sandwitched between them to form good electrical contact for the structures. The performance of the diodes was observed to be poor for diodes joined together without lead foils irrespective of the oxidation time, annealing time and even the number Cu2O/Cu structures sandwitched together. The internal and external parameters of the devices were evaluated from the current-voltage characteristics. The forward and shunt resistance were respectively found to be 0.66Ω; and 2KΩ; while the diode non-ideality factor A was found to be 64.33 and the saturation current density Jo was found to be 0.12x10-8 Acm-2. The barrier height of 0.95Ev was obtained which agrees favourably with the theoretical value of 0.9Ev – 1.3Ev.
The results present an improvement when the work of Grondahl (1920) (9) Bardeen. Brattan and Schockley
(1940’s) [6 and 9] were compared with the fabricated
THE CANTOR SET IN THE DYNAMICS OF
THE QUADRATIC FAMILY IN R
DR KB YUGUDA
Studies by Devancy [1986 and May , assert that the well known classical population growth model, p’(t) = kp, k>0, when recasted as a discrete dynamical system, leads to an interactive process, Pn+1= kpn.
By the introduction of suitable constraints however, it was shown that the former model conforms more to reality while the later leads to one of the most complicated dynamical systems imaginable, the logistic function otherwise known as the Quadratic Family Fµ(x) = µx(1-x). We shall show in the sequel, following closely the work of Devancy , that for µ>4 (precisely µ>2+√). Fµ indeed exhibits one of the most important phenomenon in dynamical systems namely, chaos!. The dynamics of Fµ on this chaotic set, otherwise known as the Cantor set is further modelled by the shift map via topological conjugacy and by so doing a better understanding of the dynamics of Fµ on the Cantor set is achieved.
SOME RECENT ADVANCES IN THE THEORY
OF TIKHONOV REGULARIZATION: PART I
The classical (or ordinary) Tikhonov regularization method is widely used in science and technology to deal with a major difficulty associated with linear and nonlinear inverse problems. However, despite the extensive application of the classical Tikhonov method, the solution it gives does not converge optimally among all regularization methods. In this regard, this paper reports results that may be of interest to the scientist, engineer and the mathematician alike.
If the data is sufficiently smooth, then a nearly op0timal order coergence can be expected from a high order version of the Tikhonov method. The superior version treated herein is the “iterated Tikhonov regularization”, whose numerical realization is not seriously more expensive than the classical method. Regarding the convergence rates obtainable, an alternative to the iterated Tikhonov regularization is to apply the classical Tikhonov method in scales of Banach spaces.
The smoothness of the (error-free) data translates to a corresponding smoothness of the exact solution. Unfortunately, in practice neither the exact solution nor its smoothness is known. It is possible to implement the iterated Tikhonov regularization and obtain optimal order convergence without precise information about the smoothness of the exact solution. But the convergence rates depend on the smoothness of the solution. A scheme is suggested in this paper for estimating the smoothness parameter in the practical implementation of the iterated Tihkonov regularization.
Most of the discussion herein is approximative rather than numerical. Scientists and engineers may wish to try out finite-dimensional examples from their fields of study to gauge the practical viability and utility of the reported theoretical advances.
A NUMBER ANALYSISOF THE VIBRATION OF TWO
RIGID BODIES ON AN ELASTIC HALF SPACE
CHRISTOPHER O IZELU
A study of the 6-degree of freedom vibration of two rigid bodies in close vicinity on an elastic half space is presented. It is of interest to establish the effect of the presence of one of the bodies on that which is subject to excitation. The Boundary Integral Equation (BIE) method is used in conjunction with the Thau’s Elastic Wave Decomposition Equation (EWDE) to obtain numerical solution of the problem which is governed by the Navier’s Equilibrium of a time harmonic motion. The dynamic stiffness and compliance of the half space, and the dynamic response amplitude of the system are computed for given values of the frequency factor, poisson’s ratio, and mass ratio. The results obtained show that the presence of a nearby unexcited rigid body tends to reduce the response amplitude of the body which is excited.
A NOVEL APPROACH TO THE DESIGN OF SIMPLE
PARALLEL – COUPLED MIRCOSTRIP LINES
Although design considerations for microstrip lines directional couplers are available, the approach is hampered because the coupler parameters (Coupling Factor, Directivity, Isolation and Transmission) are often theoretically defined and, therefore, not fully appreciated.
A new design procedure for simple parallel microstrip line couplers is presented. The procedure enables experimental verification of the degree of coupling and directivity, based on a simple configuration, as functions of separation distance and frequency. The approach and experimental results are presented, and can be applied to design simple microstrip line directional coupler of given specifications.