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Biomedical subjects

M Moussavi

Publications and source records attributed to M Moussavi.

6 recordsLinked to original sources
PubMed2002

Chemical pretreatment of formaldehyde-containing effluents.

Lime was found in this study to be an efficient reagent to lower the concentration of formaldehyde in highly concentrated effluents down to and below the limits suitable for biological treatment systems. The results show that the reactions leading to formaldehyde elimination can be divided in two steps. In the first step, the reaction is relatively slow. More than two-thirds of the original formaldehyde disappears in the second step in a period as short as one-third of the first step. Such trend is followed in a temperature range of up to 92 degrees C. Economical considerations suggest maintaining the conditions of the process around the ambient temperature with no heat requirement. It was noticed that the efficiencies of formaldehyde removal better than 99% could be achievable even around room temperature. However, these efficiencies would result in quite a shorter period of time if the temperature was raised. The mathematical representation for the rate of formaldehyde removal was found to appear with an exponential behavior. It will be seen that the rate of formaldehyde removal is strongly dependent on temperature. The present survey proves that the formaldehyde-containing effluents can be treated in a pretreatment step by lime to maintain the formaldehyde concentration in a range that is safe for biological treatment systems.

Calcium Compounds↗
PubMed1994

Harmonic distortion caused by electrode polarisation.

Steady-state measurements of the electrical properties of electrodes immersed in physiological saline were taken with small- and large-amplitude sinusoidal voltages (30 m V-1 V) in the frequency range 0.2 mHz-2 Hz. Impedance magnitude and phase, and the first four Fourier series coefficients of the polarised current were measured. The dependence of the polarisation admittance on input current intensity was modelled with the linear relationship proposed by Schwan. This model predicts harmonics in the non-linear range for AC overpotentials up to several hundred millivolts. Observed values deviated from theoretical values. Reasons for such deviations are discussed. The study of harmonic distortion appears to be a useful tool to monitor and predict the non-linear behaviour of the interface and other dielectric phenomena.

Electric Impedance↗
PubMed1993

Lithium phthalocyanine: a probe for electron paramagnetic resonance oximetry in viable biological systems.

Lithium phthalocyanine (LiPc) is a prototype of another generation of synthetic, metallic-organic, paramagnetic crystallites that appear very useful for in vitro and in vivo electron paramagnetic resonance oximetry. The peak-to-peak line width of the electron paramagnetic resonance spectrum of LiPc is a linear function of the partial pressure of oxygen (pO2); this linear relation is independent of the medium surrounding the LiPc. It has an extremely exchange-narrowed spectrum (peak-to-peak line width = 14 mG in the absence of O2). Physicochemically LiPc is very stable; its response to pO2 does not change with conditions and environments (e.g., pH, temperature, redox conditions) likely to occur in viable biological systems. These characteristics provide the sensitivity, accuracy, and range to measure physiologically and pathologically pertinent O2 tensions (0.1-50 mmHg; 1 mmHg = 133 Pa). The application of LiPc in biological systems is demonstrated in measurements of pO2 in vivo in the heart, brain, and kidney of rats.

Animals↗
PubMed1991

Measurements of pertinent concentrations of oxygen in vivo.

A new method able to measure the concentration of oxygen in complex biological systems, including in vivo, has been developed using low-frequency EPR and newly characterized free radicals that are very sensitive to the concentration of oxygen. The free radicals (fusinite and lithium phthalocyanine) are very stable in tissues (for at least 150 days), apparently nontoxic, and can reflect oxygen concentrations that are less than the Km of cytochrome oxidase (0.1 microM or lower). Their biological stability is indicated by the fact that repeated measurements with fusinite of the concentration of oxygen in skeletal muscle have been made in the same animal for more than 150 days without any change in sensitivity or signs of toxicity.

Animals↗
PubMed1990

Nonlinear phenomenon of interfacial polarization immittance of a Pt electrode.

Description of a computerized, automated method to measure the interfacial polarization immittance of a Pt electrode in nonlinear range is presented. The classical three-electrode setup is used for measurements in conjunction with a special purpose software implemented on a Unix computer using C language. A collection of data at very low frequencies (below 2 Hz) and at high input intensities with various dc biases imposed on the input are presented to show the behavior of the interface in nonlinear range. The instrument also provides on-line harmonic analysis of the output signal, by calculating the first four Fourier series coefficients, in response to a pure sinusoidal input.

Electrodes↗