Biomedical subjects
F Adib
Publications and source records attributed to F Adib.
Initial Heats of H(2)S Adsorption on Activated Carbons: Effect of Surface Features.
The sorption of hydrogen sulfide was studied on activated carbons of various origins by means of inverse gas chromatography at infinite dilution. The conditions of the experiment were dry and anaerobic. Prior to the experiments the surface of some carbon samples was oxidized using either nitric acid or ammonium persulfate. Then the structural parameters of carbons were evaluated from the sorption of nitrogen. From the IGC experiments at various temperatures, heats of adsorption were calculated. The results showed that the heat of H(2)S adsorption under dry anaerobic conditions does not depend on surface chemistry. The dependence of the heat of adsorption on the characteristic energy of nitrogen adsorption calculated from the Dubinin-Raduskevich equation was found. This correlation can be used to predict the heat of H(2)S adsorption based on the results obtained from nitrogen adsorption. Copyright 1999 Academic Press.
Effect of pH and Surface Chemistry on the Mechanism of H(2)S Removal by Activated Carbons.
The performances of three wood-based activated carbons as adsorbents of hydrogen sulfide were evaluated by dynamic breakthrough testing. The subsequent products of H(2)S oxidation on the carbon surfaces were analyzed. The adsorbents were studied using sorption of nitrogen, thermal analysis, Boehm titration, FTIR, ion chromatography, and temperature programmed desorption. Based on the results, the effects of surface chemistry and structural features on the yield of water soluble products and on the regenerability of the exhausted carbons were evaluated. The results showed that the breakthrough capacity and the yield on regeneration depend on the average pH of the carbon surface related to the pH in local pore environment. When the surface is very acidic, the dissociation of H(2)S is suppressed resulting in a very small concentration of hydrogen sulfide ions and thus in the formation of highly dispersed sulfur. Such conditions are favorable for oxidation of sulfur to S(4+) and S(6+). When the surface is less acidic the degree of dissociation is higher and the creation of polymeric elemental sulfur species resistant to further oxidation is more favorable. A small increase in pH (half a unit) in the acidic range results in a 15-fold increase in hydrogen sulfide breakthrough capacity accompanied by only a one third decrease in the yield of sulfur oxides. Copyright 1999 Academic Press.
Effect of Surface Characteristics of Wood-Based Activated Carbons on Adsorption of Hydrogen Sulfide.
Three wood-based commercial activated carbons supplied by Westvaco were studied as adsorbents of hydrogen sulfide. The initial materials were characterized using sorption of nitrogen, Boehm titration, potentiometric titration, water sorption, thermal analysis, and temperature-programmed desorption. The breakthrough tests were done at low concentrations of H2S in the input gas to simulate conditions in water pollution control plants where carbon beds are used as odor adsorbents. In spite of apparent general similarities in the origin of the materials, method of activation, surface chemistry, and porosity, significant differences in their performance as hydrogen sulfide adsorbents were observed. Results show that the combined effect of the presence of pores large enough to accommodate surface functional groups and small enough to have the film of water at relatively low pressure contributes to oxidation of hydrogen sulfide. Moreover, there are features of activated carbon surfaces such as local environment of acidic/basic groups along with the presence of alkali metals which are important to the oxidation process. Copyright 1999 Academic Press.
Musculoskeletal etiology and therapy of craniomandibular pain and dysfunction.
A number of diverse symptoms, conventionally diagnosed and treated as individual problems, exist in combination in the craniomandibular pain and dysfunction patient. This chapter explores musculoskeletal dysfunction of the area as a common etiologic factor for head and neck pain. The electronically derived data, reported in 68 case histories, indicate that a common measurable etiology is responsible for the many ostensibly diverse manifestations of craniomandibular pain and dysfunction. Both quantitative and subjective data support the etiologic validity of the diagnosis. The basis for the effectiveness of the reported therapy rests on diagnosis of a skeletal malrelation of the mandible to the cranium that poses sustained accommodative demand on the neuromusculature.
Can electrical stimulation be used to establish a physiologic occlusal position?
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Effect of variation in manipulative force on the repetitiveness of centric relation registration: a computer-based study.
Measurement of the influence of the degree of applied force on the resulting retruded border position of the mandible established that the position varied significantly in all three dimensions according to variation in the amount of force. On the basis of the analysis of the t-test (sampling error of 8%), it can be concluded that increasing the manipulative force on the mandible in the general male population will result in a significant three-dimensional increase in the distance from centric occlusion to centric relation. The measurement data document the variability of the retruded centric relation position according to the different amounts of applied retrusive force. The data question the choice of the retruded border position on the basis of its clinical repetitiveness.
Effects of the Myo-monitor on cardiac pacemakers.
Interference of Myo-monitor stimulus on normal function of cardiac pacemakers depends on the sensitivity of the pacemaker and the amplitude setting of the stimulator. Because of electrical isolation of the fixed-rate pacemaker, it is resistant to interference and is unaffected by the Myo-monitor.