Free boundary problems with nonlinear diffusion occur in various applications, such as solidification over a mould with dissimilar nonlinear thermal properties and saturated or unsaturated absorption in the soil beneath a pond. In this article, we consider a novel inverse problem where a free boundary is determined from the mass/energy specification in a well-posed one-dimensional nonlinear diffusion problem, and a stability estimate is established. The problem is recast as a nonlinear least-squares minimisation problem, which is solved numerically using the
The research involved a rapid, automated and highly accurate developed CFIA/MZ technique for estimation of phenylephrine hydrochloride (PHE) in pure, dosage forms and biological sample. This method is based on oxidative coupling reaction of 2,4-dinitrophenylhydrazine (DNPH) with PHE in existence of sodium periodate as oxidizing agent in alkaline medium to form a red colored product at ʎmax )520 nm (. A flow rate of 4.3 mL.min-1 using distilled water as a carrier, the method of FIA proved to be as a sensitive and economic analytical tool for estimation of PHE.
Within the concentration range of 5-300 μg.mL-1, a calibration curve was rectilinear, where the detection limit was 3.252 μg.mL
A newly photometric analytical method characterized by its speed and sensitivity was developed for the determination of folic acid in pure and pharmaceutical samples via its oxidation to reddish-orange coloured complex through oxidation by cerium (IV) sulphate in aqua medium using homemade Ayah 3Sx3-3D-solar cell CFI photometer. The colored species were determined using supper bright green light emitting diode (LED) as a source. A 100μl was taken as a best sample volume for the determination of folic acid. The linearity of calibration curve for the instrument response versus folic acid concentration was 0.005-20 mmol.L-1 while the L.O.D. was 0.5 mol.L-1 from the stepwise dilution for the minimum concentration of lowest concentration
... Show MoreA simple, rapid and sensitive method for the analysis of Atenolol in pure and pharmaceutical preparation as an alternative analytical procedure were developed by continuous flow injection analysis via turbidimetric (T180o) and scattered light effect at two opposite position (2N90o). The method is based upon the formation of white precipitate for the ion pair compound by phosphomolybidic acid with Atenolol in aqueous medium. The precipitate is measured via the attenuation of incident light and scattering of the incident light in two opposite direction namely +90o and -90o angle were measured. Chemical and physical parameters were investigated. The linearity of Atenolol is ranged from (0.1-11) mmol.L-1, with correlation coefficient r=0.993
... Show MoreThe development of a reversed phase high performance liquid chromatography fluorescence method for the determination of the mycotoxins fumonisin B1 and fumonisin B2 by using silica-based monolithic column is described. The samples were first extracted using acetonitrile:water (50:50, v/v) and purified by using a C18 solid phase extraction-based clean-up column. Then, pre-column derivatization for the analyte using ortho-phthaldialdehyde in the presence of 2-mercaptoethanol was carried out. The developed method involved optimization of mobile phase composition using methanol and phosphate buffer, injection volume, temperature and flow rate. The liquid chromatographic separation was performed using a reversed phase Chromolith® RP-18e column
... Show MoreA newly developed analytical method characterized by its speed and sensitivity for the determination of metformin-HCl via the formation of complex for metformin-HCl-OH--copper(II) ion from the gel bead system by continuous flow injection analysis. The method is based on the imbedded copper(II) ion in the gel bead structure can be used in the reaction for the formation of red –magneta colour complex(λmax. =530nm) formed by direct reaction of the drug with the released copper (II) ion from the gel bead in alkaline medium. Linear dynamic range for the absorbance versus metformin concentration was 0.001-1 mmol.L-1 while C.O.D was (r2% =95.33%) . The L.O.Q was 0.868mmol.L-1.L.O.D (S/N=3)=0.5μmol.L-1 from the step wise dilution for the min
... Show MoreMany geophysical methods have been applied to locate groundwater in Nigeria’s rural and urban villages. Locating groundwater in low permeability formations like shales and siltstones is even more challenging due to the difficulty of mapping fracture zones within these formations. The fracture zones serve as potential aquifers in low permeability formations and have been the object of groundwater search in shales, siltstones and other low permeability formations. The electrical resistivity method has proven helpful in fracture mapping within low permeability formations due to the existing resistivity contrast usually observed between the fractured and non-fractured sections in the Shales and Siltstones. Three vertical electri
... Show MoreUsing sodium4-((4,5-diphenyl-imidazol-2-yl)diazenyl)-3-hydroxynaphthalene-1-sulfonate (SDPIHN) as a chromogenic reagent in presence of non-ionic surfactant (Triton x-100) to estimate the chromium(III) ion if the wavelength of this reagent 463 nm to form a dark greenish-brown complex in wavelength 586 nm at pH=10,the complex was stable for longer than 24 hours. Beer's low, molar absorptivity 0.244×104L.mol-1.cm-1, and Sandal's sensitivity 0.021 µg/cm2 are all observed in the concentration range 1-11 µg/mL. The limits of detection (LOD) and limit of quantification (LOQ), respectively, were 0.117 µg/mL and 0.385µg/mL. (mole ratio technique, job's method) were employed to
... Show MoreSteps were taken to obtain the Kojic acid crystals from local fungal isolation A. flavus WJF81 by separating the fermentation products from the fungus mycelium from the production plant at the centrifuge at a speed of 5000 cycles for 10 minutes. The extraction was followed by ethyl acetate then supernatant concentrate by using rotary evaporator, and dried with heat oven 37ºC. Long, yellowish, pristine acid crystals were obtained that examined the optical microscope with a magnification force of 10x and 40x. The melting point of kojic acid was determined between 152.9-153.5 °C Results of the diagnosis of Kojic acid by applying High pressure liquid chromatography HPLC technique showed that the acid was at one peak, which was close to the
... Show MoreA newly flow injection-turbidimetric method characterized by it is speed and sensitivity has been developed for the determination of Amiloride in pure and pharmaceutical preparations. It is based on the formation of yellowish white precipitate for the Amiloride-phosphomolybidic acid ion pair in aqueous medium. Turbidity was measured by Ayah 6Sx1-T-1D solar cell CFI analyser via the attenuation of incident light from the surfaces precipitated particles at 0-180. The Chemical and physical parameters were investigated. Linear dynamic range for the attenuation of incident light versus Amiloride concentration was of 0.005-10 mmol.L-1, with the correlation coefficient (r) of 0.9986 , while the percentage linearity (r2%) was 99.71%. The L.O.
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