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RISS 인기검색어
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- 저자 : Rambo Carlos R. (검색결과 2 건)
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Humberto R. Gamba,Marcos V. H. Rambo,Gustavo B. Borba,Joaquim M. Maia,Carlos A. S. Ramos 대한의용생체공학회 2013 Biomedical Engineering Letters (BMEL) Vol.3 No.3
Purpose Electronic foramen locators are widely used to locate the apical foramen (AF), by measuring the electrical impedance between the electrodes (ZE). There is no in vivo study that completely characterizes ZE as a function of frequency and endodontic file tip position. The results of in vivo studies of the impedance ZE and a coefficient that can be used to locate the AF are presented. Methods An electronic device was specially built to study ZE. Ten root canals were used in the experiment. The spectral attenuation of ZE was in vivo measured with the endodontic file tip placed at -3.0, -2.5, -2.0, -1.5, -1.0, -0.5 and zero millimeters from the root canal AF. At each file position the spectrum attenuation was modeled. Based on the attenuation models an endodontic spectral attenuation coefficient (ESAC)was defined. Results The in vivo results demonstrate that the spectral attenuation of the electrical impedance ZE has an exponential decay in the frequency range of the study. It was verified that ESAC can be correlated to the distance between the endodontic file tip and the apical foramen. The ESAC accuracy was assessed and the results showed that it can locate the AF with accuracy better than 0.5mm. Conclusions The spectral attenuation of ZE has an exponential decay for all file tip distances from the AF. It supports the feasibility of ESAC to accurately locate the root canal AF. Moreover, using frequencies steps of one octave makes the implementation of ESAC in an embedded system easier.
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Enhanced CO2 capture by cupuassu shell-derived activated carbon with high microporous volume
Cruz Orlando F.,Campello-Gómez Ignacio,Casco Mirian E.,Serafin Jarosław,Silvestre-Albero Joaquín,Martínez-Escandell Manuel,Hotza Dachamir,Rambo Carlos R. 한국탄소학회 2023 Carbon Letters Vol.33 No.3
Here, we report the preparation of microporous-activated carbons from a Brazilian natural lignocellulosic agricultural waste, cupuassu shell, by pyrolysis at 500 ºC and KOH activation under different experimental conditions and their subsequent application as adsorbent for CO2 capture. The effect of the KOH:precursor ratio (wt/wt%) and the activation temperature on the porous texture of activated carbons have been studied. The values of specific surface area ranged from 1132 to 2486 m2/g, and the overall micropore volume ranged from 0.73 to 1.02 cm3/g. Carbons activated with 2:1 ratio of KOH and activation temperature of 700 ºC presented a CO2 adsorption at 1 bar of 7.8 and 4.4 mmol/g at 0 °C and 25 ºC, respectively. The isosteric heat of adsorption, Qst , was calculated for all samples by applying the Clausius–Clapeyron approach to CO2 adsorption isotherms at both temperatures. The values of CO2 adsorption capacities are among the highest reported in the literature, especially for activated carbons produced from biomass.
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