Dependence of temperature variation of the Jahn-Teller potential well splitting and phase transition temperature in CuxZn1-xTiF6.6H2O crystals on Cu2+ ion concentration, x
December 2008
The energy Eo by which one of the three Jahn-Teller potential wells becomes lower than the other two in Cu2+:ZnTiF6.6H2O single crystal at phase transition temperature, Tcl are determined at temperatures below Tcl for different Cu2+concentrations from the electron paramagnetic resonance (EPR) spectra. As the sample is cooled, it is found that for high Cu2+ concentration, Eo increases below...
Numerical simulation of a one-dimensional shock tube problem at supercritical fluid conditions
December 2008
The numerical computation of supercritical fluid flows is extremely challenging because of the complexity of the physical processes and the disparity of the space and time scales involved. Supercritical fluids exhibit large density fluctuations especially very close to the critical region. In this region, the perfect gas law is no longer valid and has to be replaced by a specific equation of state (EoS) as, for...
A text based approach to content based information retrieval for Indian medicinal plants
November 2008
The usage of plants as foodstuff and also medicine is universal. It is important and yet a difficult task to identify the medicinal plants’ species present in the universe through computers. Development of a machine vision system for medicinal plants is a dire necessity as this tacit knowledge dies with the experts in the field. Hence it is helpful to understand and manage these medicinal plants in the interest of...
Inhibition of the corrosion of mild steel in H2SO4 by 5-amino-1-cyclopropyl-7-[(3R, 5S) 3, 5-dimethylpiperazin-1-YL] -6, 8-difluoro-4-oxo-uinoline-3-carboxylic acid (ACPDQC)
November 2008
Adsorption and inhibitive efficiencies of ACPDQC on mild steel corrosion have been studied using gasometric and thermometric techniques. ACPDQC is found to be a good inhibitor for the corrosion of mild steel in H2SO4 solution. The inhibition efficiencies of ACPDQC were found to decrease with increase in temperature but increased with increase in the concentration of the extract. Thermodynamic/adsorption...
Kinetic and thermodynamic study of the adsorption of Pb (II) from aqueous solution to the natural and treated bentonite
November 2008
Lead (Pb) is one of the major environmental pollutants. Adsorption appears to be the most widely used for the removal of heavy metals. The aim of this work is to investigate the adsorption potential of commercial natural bentonite (NB) in the removal of Pb (II) ions from aqueous solution. The effect of different variables, such as, concentration of Pb, mass of NB, pH, time, NB washing and heat treatment and temperature...
Determination of lead, cadmium and mercury in surrounding water and organs of some species of fish from Ikpoba river in Benin city, Nigeria
November 2008
The mean concentration of some heavy metals (lead, cadmium and mercury) in the muscles and the organs of some common species of fish: Metacembelus Iconnbergii, Clarias lazera, Citarinus citharus, Tilapia zilli and Erpetoichithy were investigated using atomic absorption spectrophotometric method. The mean concentrations of lead in the muscle, kidney and liver were in the ranges of 0.00 – 0.004...
Chemical and surface properties of longan seed activated charcoal
October 2008
In order to study the chemical compositions and surface properties of longan seed (Daw) activated charcoal, the influences of a phosphoric acid activation process was investigated before and after carbonization. Carbonization temperatures in this study were ranged from 400 - 800°C. It was found that higher carbonization temperatures resulted in a high amount of organic carbon and ashes, while the volatile matters...
Effect of kaolin clay addition on mechanical properties of foundry sand moulds bonded with grades 1 and 2 Nigerian acacia species
October 2008
The research studied effects of addition of kaolin clay on mechanical properties of sand moulds bonded with grades 1 and 2 Nigerian acacia species exudates. The properties included green and dry compressive strength; permeability and hardness; shatter index and the moisture content. Green and dry sand mould specimens bonded with composite mixtures of kaolin clay and each of grades 1 and 2 acacia exudates were subjected...
Application of vertical electrical sounding method to decipher the existing subsurface stratification and groundwater occurrence status in a location in Edo North of Nigeria
October 2008
The interpretation of two resistivity curves over Iyakpi town within geologic terrain often referred to as Ajali formation which bears false-bedded sandstone with associated clay and shale intervals in the bottom section indicates that the area has an abundant groundwater potential. Existence of productive borehole in the study area was field-confirmed. The study area is said to have a standing history of abortive...
Thermodynamic properties and relative stability of polybrominated phenoxathiins by density functional theory
October 2008
The thermodynamic properties of 135 polybrominated phenoxathiins (PBPTs) in the ideal gas state at 298.15 K and 1.013×105 Pa have been calculated at the B3LYP/6-31G* level using Gaussian 03 program. The isodesmic reactions were designed to calculate standard enthalpy of formation (ΔfHÓ©) and standard free energy of formation (ΔfGÓ©) of PBPTs congeners. The relations of these thermodynamic...
A class of fixed denominator rational integrators
October 2008
Existing methods such as Niekerk (1987) and Fatunla (1982) are effective but could not handle problem whose initial value is zero. In this paper, we designed and implemented a class of free denominator rational integrators for the solution of initial value problems (IVPs) in ordinary differential equations (ODES), particularly for the case of Stiff and singular problems. The class of integration obtained was found to be...
Biosorption of Zn(II) from an aqueous solution by Erythrina variegata orientalis leaf powder
September 2008
In the present investigation, the biosorption is carried out in a batch process to test the suitability of abundantly and freely available plant based material, Erythrina variegata orientalis (Indian coral tree) leaf powder, as an adsorbent for removal of Zn(II) from aqueous solution. The influence of various process parameters like agitation time, adsorbent size and dosage, pH of the aqueous solution and...
Estimation of air aerosol number concentration by indirect method
September 2008
The estimation of the air aerosol number concentration variation was carried out in this work making use of data obtained from the Bauchi Road Campus of the University of Jos, Plateau State, Nigeria in 1990. The aerosol number concentration was determined indirectly, making use of the intensity of light scattered by particles. The scattered light intensity is proportional to the average number...
Empirical models for the correlation of global solar radiation with meteorological data for Iseyin, Nigeria
September 2008
A number of multilinear regression equations were developed to predict the relationship between global solar radiations with one or more combinations of the following weather parameters: clearness index, mean of daily temperature, ratio of maximum and minimum daily temperature, relative humidity and relative sunshine duration for Iseyin Nigeria for five years (1995 - 1999). Using the Angstrom model as the base,...
Design and implimentaton of a model (ATLC-2007DNM) of an automated traffic light controller
September 2008
In this work, a model of an automated traffic light controller (ATLC –2007DNM) had been designed and implemented, using electronic instrumentation and experimental techniques in electronic engineering and physics, to manage the traffics at the busy four- ways junctions along Sahuda road in Mubi North,Adamawa State, Nigeria. The designed was achieved with the help of low power transformer rating of 3.6 watts,...
Characterization of a stable isoenzyme of malate dehydrogenase (MDH1) from blood stream Trypanosoma vivax
September 2008
MDH1, isoenzyme of malate dehydrogenase from blood stream Trypanosoma vivax was characterized. The enzyme was active over a broad pH and temperature range with optimal values of 5.0 and 35oC respectively. The energy of activation was 20.58kj/mol and the pKa values were 6.8 and 7.8 implicating ionizable groups at the catalytic site. Kinetic studies conducted in the direction of oxaloacetate reduction gave...
Studies of instantaneous thermal refraction and nonlinear scattering effect in C60/toluene solution
September 2008
Nonlinear refraction and scattering effect properties of C60/toluene solution were studied by using the Z-scan technique and 532 nm laser delivering 4 nanosecond (ns) pulses. With single ns pulse, reverse saturable absorption (RSA) and negative nonlinear refraction were observed, and the nonlinear scattering effect in the solution could not be ignored when the pulse energy was large enough. The refraction cross-section...
Fe(III) and Co(II) complexes of mixed antibiotics: synthesis, characterization, antimicrobial potential and their effect on alkaline phosphatase activities of selected rat tissues
August 2008
Two new mixed ligand metal complexes of Fe(III) and Co(II) chloride hexahydrate salts were prepared using standard methods. Ampicillin trihydrate and oxytetracycline hydrochloride antibiotics were used as ligands. Chemical analysis including conductivity measurements, molecular weight determination and spectroscopic studies were used to propose the geometry and mode of binding of the ligands to metal ions. Both ligands...
On boundry value problems for random nonlinear differential equations
August 2008
This paper deals with the nonlinear boundary value problem including random effects. An approximate probability distribution function is constructed by numerical integrated of a set of related deterministic problems. Convergence of the approximate distribution function in the actual distribution function is established. Key words: Random boundary value problem, distribution function, numerical...
A class of exponentially - Fitted third derivative methods for solving stiff differential equations
August 2008
A class of exponentially fitted third derivative methods of order eight for solving stiff initial value problems in ordinary differential equations is derived. The derivation of the method which allows free parameters is cast into predictor-corrector form for efficient implementation. The analysis of the method shows that it is A-stable. The numerical implementation of the method to standard stiff problems shows that it...
Effect of annealing on the resistivity of copper (I) oxide solar cells
August 2008
The effect of annealing on the resistively of copper (I) oxides (Cu2O) samples has been investigated in detail. The resistivily of the sample is a function of the power output of such Cu2O solar cell. Results revealed that the annealing of Cu2O samples improves the output performance compared to that of unannealed samples by about 36%. The results on the resistivity of the samples oxidized at different temperatures for...
A robust observer design for chaos synchronization of uncertain systems using LMI criterion
July 2008
In this paper, considering the effect of exoteric perturbation on system’s parameters, a robust observer, based on Lyapunov theory, is designed for the output synchronization of a class of uncertain systems when the full state vector is not available. With the help of LMI criterion and then using the MATLAB LMI Toolbox, the observer gain L is derived, which can not only make the...
Complexation of cobalt (II) with nicotinohydroxamic acid and its microbial sensitivity
July 2008
Complex of cobalt (II) with nicotinohydroxamic acid (NHA) has been investigated by spectroscopic method at 25 ± 0.1oC in aqueous solution of 0.1mol dm-3 ionic strength. The results reveal the sole formation of 1:2 complex at equilibrium. Spectra and magnetic studies of the isolated complex indicate octahedral mixed coordination mode (N.O). Microbial sensitivity test on eight micro-organism (that is, four...
Lamda-mu-rho technique as a viable tool for litho-fluid discrimination - The Niger-Delta example
July 2008
The focus of this paper is to discriminate fluid and lithology in the tertiary Niger Delta using the Lamda-mu-rho technique. This involves the use of basic rock Physics, Amplitude Variation with Offset (AVO), and seismic amplitude inversion to show the effectiveness of this technique in an oil sand reservoir. The data used in this study include pre-stack seismic data and well log data. The result shows the effectiveness...
Study on the morphology of polyacrylamide – silica fumed nanocomposite thin films
June 2008
Silica fumed nanoparticles were dispersed in polyacrylamide thin films by direct mixing. Atomic Force Microscopy study was carried out in order to analyze the surface roughness. Height distribution of surface roughness changes from Gaussian like for polyacrylamide to skew asymmetric when increasing the silica concentration. The length of the distribution tail increases, indicating the formation of multi-scale features...
Electronically tunable current mode second order high pass filter for different value of Q
June 2008
This paper presents realization of current-mode active-R filter in order to increase the speed of circuits for analog signal processing and to decrease the supply voltages of integrated circuits. The proposed filter is constructed using operational amplifiers [OA] and resistors. The circuit capable of realizing quadratic transfer function .The proposed second order high pass filter circuit works ideal for Q >=1...
Application of geochemical parameters for characterization of oil samples using GC-MS technique
June 2008
Geochemical characterization of eleven (11) oil samples has been carried out; using diagnostic biomarker parameters related to thermal maturity, organic matter source, age and depositional environment. Oleanane was only found in the Nigerian oil, serving as a primary feature in distinguishing it from other oils. All the oil samples appeared to have mixed organic matter input with samples of the same region closely...
Friedelanone and other triterpenoids from Hymenocardia acida
June 2008
The stem barks of the plant Hymenocardia acida Tul. (Hymenocardiaceae) has yielded five triterpenoids which were identified by spectroscopic methods as friedelan-3-one, betulinic acid, lupeol, β-sitosterol, stigmasterol and the fatty acid, oleic acid. These compounds are being reported for this plant material for the first time. Key words: Hymenocardia acida, hymenocardiaceae, Nigeria,...
Annual effective dose and concentration levels of heavy metals in different types of tea in Egypt
May 2008
Six marked brands of black tea (S1, S2, S4, S5, S6, and S7) and one type of green tea (S3) which commonly consumed in Egypt, were collected from local markets. The total alpha and beta gross activities in different tea samples were measured. The annual effective dose (mSv/y) for both total alpha and beta gross activities (Bq/2 gm) related to different types of tea drink corresponding to each radionuclide was...
Removal OF EMG and ECG artifacts from EEG based on real time recurrent learning algorithm
May 2008
EEG (Electroencephalograph) recording from the scalp has biological artifacts and external artifacts. Biological artifacts, which are generated, can be EMG (Electromyograph) signal, EOG (Electrooculograph) signal or ECG (Electrocardiograph) signal. These artifacts appear as noise in the recorded EEG signal individually or in a combined manner. Usually physicians are misled by...
Estimation of solar radiation at Uturu, Nigeria
May 2008
The estimation of the solar radiation at Uturu latitude 05.33oN and 06.03oN was carried out in this work. The temperature data were obtained from 5th – 31st October, 2007) using the maximum and minimum thermometer placed in the Stevenson screen at 1.5 m The Hargreaves equation was used to estimate the solar radiation at Uturu. The mean global solar radiation obtained for the period is...
Phase and conductivity dynamics of strontium hexaferrite nanocrystals in a hydrogen gas flow
May 2008
The phase and conductivity dynamics of strontium hexaferrite nanocrystals were isothermally studied at different temperatures during a constant flow of hydrogen gas at normal atmospheric pressure. The nanocrystals were prepared by self-flash combustion of acetate precursors. While the formed phase was characterized using XRD, TEM, and optical microscopy after hydrogen exposure, the electrical conductivity was in-situ...
Inhibiting effect of cetyl pyridinium chloride (CPC) on the corrosion of mild steel in acidic medium
May 2008
The inhibiting effect of Cetyl Pyridinium Chloride (CPC) on mild steel in 1M Hydrochloric acid has been studied by using three techniques namely: weight loss, electrochemical polarization and metallurgical research microscopic techniques. Results obtained reveal that CPC is good inhibitor and shows very good corrosion inhibition efficiency (IE). The IE was found to vary with concentration of inhibitor and...
Application of ultrasonic waves coupled with functional link neural network for estimation of carrageenan concentration
April 2008
In this paper, a simple functional link neural network (FLNN) model is developed for the quantification of polysaccharides using ultrasonic waves. Every material has its own intensity to absorb the sound waves. The sound absorption capability of Carrageenan is based on its concentration in the solution. The sound pressure leave obtained from the one third octave band frequency spectrum is given as input to the FLNN and...
A quadratic based integration scheme for the solution of singulo-stiff differential equations
April 2008
In this term paper, we designed a quadratic based integration scheme for the solution of initial value problem (IVPs) in ordinary differential equation (ODEs). This was achieved by considering the rational interpolating operator satisfying A class of rational integrator formula given...
Extraction of zinc (II) by triphenylphosphite (TPP) in hydrochloric acid: Kinetics and mechanism
April 2008
The extraction of Zinc (II) in chloride medium with triphenyl phosphite (TPP) in kerosene has been investigated under different experimental conditions in order to have a better understanding of the extraction mechanism. The extraction yield was found to depend on the concentrations of Zinc (II) and TPP, and pH. The extraction yield can easily be predicted based on an established linear expression. The effect of...
Thermodynamic and isothermal studies of the biosorption of cadmium (II) from solution by maize wrapper
March 2008
The removal of Cd (II) from dilute aqueous solution using maize (Zea mays) wrapper as a biosorbent was studied. The biosorption was pH-dependent with an optimum pH of 5 - 7. It was also time-dependent and maximum biosorption was obtained after 100 minutes. The adsorption isotherms obtained fitted well into the Freundlich and Langmuir isotherms. The Freundlich equation obtained was log Г = 1.0813 logCe + 0.958...
Dielectric study of moisture laden soils at X-band microwave frequency
March 2008
Interaction of electromagnetic waves with the materials of planet earth provides the information for microwave remote sensing. From the reflected wave it is possible to reveal the information, which is useful for the measurement of dielectric properties. The dielectric properties of material are function of its chemical constituents and physical properties. Measurements of real (ε’) and imaginary...
Numerical simulation of aerodynamic and thermal fields inside a cylinder of an alternative engine
March 2008
We are interested in the study of turbulent and instationary flow inside a cylinder of an alternative engine. The finite element method is used to solve equations model. As the domain of the flow is changing with time due to the moving piston, an arbitrary Lagrange eulerian technique is chosen to reply to this problem. The modelisation is based on classic k- ε model. In this paper, we will present...
Effect of mixture components on the properties of MUF resin
February 2008
The effect of disodium tetraborate decahydrate (DTD) on the properties of melamine-urea-formaldehyde (MUF) resin was studied. The leachability from the MUF resin into solvents was investigated. The solvents chosen in this research were distilled water, 10% ethanol, and 30% ethanol. The main constituents that contribute to the leaching in water are melamine, additional urea, and DTD concentrations. Based on the...
Kinetic, isotherm and thermodynamic studies of the biosorption of zinc (II) from solution by maize wrapper
February 2008
The removal of Zn2+ from dilute aqueous solution using maize (Zea mays) wrapper as the biosorbent is reported in this paper. Batch experiments were carried out to assess biosorption kinetic and equilibrium behaviour of Zn2+ by varying parameters such as pH, contact time and initial metal ion concentration at 27ºC. The analysis of residual metal ions was determined using atomic absorption...
Effect of pH and concentration on the complexation of calcium ions with humic acid extracted from composted oil palm bunches
February 2008
The reaction (complexation) between calcium ions at certain concentrations (1.000, 0.500, 0.250 and 0.125 M) and pH (2, 4, 6, and 8) and humic acid obtained from composted oil palm (Elaeis guineensis Jacq) bunches were investigated in this study. The results obtained showed that at maximum total calcium concentrated (1.000 M) few or no Ca2+ was complexed to the humic acid at pH 2 and 8 respectively, while...
On non-standard finite difference schemes for initial value problems in ordinary differential equations
February 2008
In this paper, we present the theory of non-standard finite difference schemes which can be used to solve some initial value problems in ordinary differential equations. Methods of construction and mode of implementation of these methods are also discussed. We also examine the stability properties of the constructed schemes. Keywords: Non-standard, stability, non-local approximation, initial value...
Optimizing friction behaviour of clutch facings using pin-on-disk test
February 2008
In this work, a rational approach based on Taguchi technique and Pin-on-disk test is used in order to study the friction coefficient behaviour of clutch facings as function of material formulation. Experiments were designed according to the orthogonal array L8 where the chosen factors are temperature and sliding speed. A complex interaction exists between the surface texture of the produced clutch facings and the used...
Groundwater fluoride levels in villages of Southern Malawi and removal studies using bauxite
January 2008
Dental and skeletal fluorosis are known to be caused by excessive fluoride ingestion particularly from drinking water sources. Dental fluorosis is common in some parts of Malawi but studies on fluoride levels of drinking water sources have not been adequately done. This paper presents our findings in fluoride levels of some drinking water sources in selected rural areas of Southern Malawi and studies on the potential of...
On the solution of an HIV- immune dynamic system
January 2008
Some mathematical properties of nonlinear system associated with an HIV- Immune dynamic model will be given. The considered model will be solved numerically. The numerical method permits the examination of the behaviour of the dynamic system on long-term. In the same time, it is easy to implement, fast convergent and has a very competitive stability results. Numerical results demonstrate the effect of improving the...
Complex of nickel (II) with isonicotinohydroxamic acid
January 2008
Isonicotinohydroxamic acid (INHA) was synthesized, characterized, and its pKa determined spectrophotometrically as 8.680.05 at 25oC and in buffers of 0.1 mol dm-3 ionic strength (I). A spectroscopic investigation of its reaction with NiII in aqueous solution revealed the sole formation of the 1:2 complex at equilibrium. Spectra and magnetic studies of the isolated complex indicate octahedral coordination via...
Extraction of Eu(III) from nitrate medium by CYANEX921 using solvent extraction technique
January 2008
The extraction of Eu(III) was investigated from nitrate medium by CYANEX921 (C921). It was found that the chemical formula of the main extracted species in the organic phase is Eu(NO3)3.3[C921] for extraction by C921. It was found that the Eu(III) percent extracted from toluene, n-hexane, cyclohexane and kerosene was nearly similar but with faster phase separation in favor of toluene. The relation between the shaking...
Rb-Sr and U-Pb age dating of granite rocks by inductively coupled plasma mass spectrometry
January 2008
Inductively coupled plasma-mass spectrometry (ICP-MS) was used as alternative to thermal ionization mass spectrometer (TIMS) for age dating of granite samples originating from different magmatic volcanic rock formations on the Arabian shield. Cation exchange chromatography was used to avoid isobaric overlap of 87Rb with87Sr and 204Hg with 204Pb ions signals to the largest possible extent, while...
Calculation of the Mie scattering field inside and outside a coated spherical particle
January 2008
A procedure to compute intensity distributions generated by the Mie scattering from a single coated sphere is described, and applied to a nanoshell and a microshell. The obtained information on the near-field intensity and the absorbed energy density is shown to be useful in predicting optical properties of the core-shell structure for applications. Key words: Nanoparticles, Mie theory,...
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