The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Julián Garrido - One of the best experts on this subject based on the ideXlab platform.
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simultaneous effect of ph temperature ionic strength and Initial Concentration on the retention of lead on illite
Applied Clay Science, 2005Co-Authors: Jesús C. Echeverría, Irantzu Zarranz, Juncal Estella, Julián GarridoAbstract:Abstract Sorption of metal ions by clay minerals is a complex process involving different mechanisms, and controlled by different variables that can interact. The aim of this work was to study the retention mechanisms of Pb 2+ ions on illite. We obtained Pb 2+ sorption isotherms at constant pH, sorption edges as a function of pH, sorption isotherms at 5, 25 and 45 °C (pH = 5.5), and response surfaces of the simultaneous effect of pH, Initial Concentration, ionic strength, and temperature on the retention of Pb 2+ ions on illite. Surface topography and atomic composition of illite samples doped with Pb 2+ were studied by scanning electron microscopy and X-ray fluorescence microanalysis. Below pH 4.5, sorption of Pb 2+ ions on illite is via ion exchange with H 3 O + and Na + ions that saturated the exchange sites, where the exchange with Na + is the main mechanism between pH 3.5 and 4.5. Al 3 + ions whose Concentration in solution increases with decreasing pH can also compete with Pb 2+ ions. For pH above 5.0, proton stoichiometry was higher than 1.0, and the effect of ionic strength on the amount of Pb 2+ retained decreased with pH; in fact, at pH 6.8, the amount adsorbed was practically 100% and independent of ionic strength. The pronounced decrease in the intensity of the OH-stretching band for Pb–illite sample at pH 7.0 suggests that Pb 2+ ions had lost the inner hydration sphere. The analysis of images obtained by SEM from 3 mM Pb 2+ solutions with and without illite showed particles with the same morphology, which indicate a homogenous lead precipitation from the solution. For pH values higher than 4.5, increase in the temperature favored the retention of Pb 2+ ions.
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Simultaneous effect of pH, temperature, ionic strength, and Initial Concentration on the retention of Ni on illite
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003Co-Authors: Jesús C. Echeverría, J. Indurain, E. Churio, Julián GarridoAbstract:Abstract Adsorption of metals by clay minerals is a complex process involving different mechanisms, and controlled by different variables that can interact. The aim of this work was to study the simultaneous effect of pH, Initial Concentration, ionic strength, and temperature on the retention of Ni on illite by Response Surface Methodology. As fitting and analyzing response surfaces is greatly facilitated by the proper choice of experimental conditions, we previously obtained Ni adsorption isotherms at constant pH and adsorption edges as a function of pH. Adsorption isotherms at 15, 25 and 35 °C (pH 7.5) were performed to deduce thermodynamic parameters. Surface topography and atomic composition of illite samples doped with Ni were studied by scanning electron microscopy and X-ray fluorescence microanalysis. Below pH 7, ionic strength had the largest effect on Ni adsorption illite suggesting that ion exchange with H 3 O + and Na(I) ions that saturated the exchange sites was the main retention mechanism; Al(III) ions whose Concentration in solution increases with decreasing pH can also compete with Ni(II) ions. For pH values higher than 7, the amount of Ni retained increased with the Initial Concentration, pH and temperature; the effect of ionic strength on the amount of Ni(II) retained decreased with pH, being negligible at pH 8. Precipitation was nucleated by illite surfaces; as Ni percentage in illite surface increased, Si percentage decreased. These facts are compatible with a more specific process involving hydrolyzed species, where nickel can associate with illite as an inner sphere complex.
Porjai Pattanittum - One of the best experts on this subject based on the ideXlab platform.
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The Cochrane Library - High Initial Concentration versus low Initial Concentration sevoflurane for inhalational induction of anaesthesia
The Cochrane database of systematic reviews, 2016Co-Authors: Polpun Boonmak, Suhattaya Boonmak, Porjai PattanittumAbstract:Background Sevoflurane induction for general anaesthesia has been reported to be safe, reliable and well accepted by patients. Sevoflurane induction uses either low or high Initial Concentrations. The low Initial Concentration technique involves Initially administering a low Concentration of sevoflurane and gradually increasing the Concentration of the dose until the patient is anaesthetized. The high Initial Concentration technique involves administering high Concentrations from the beginning, then continuing with those high doses until the patient is anaesthetized. This review was originally published in 2013 and has been updated in 2016. Objectives We aimed to compare induction times and complication rates between high and low Initial Concentration sevoflurane anaesthetic induction techniques in adults and children who received inhalational induction for general anaesthesia. We defined 'high' as greater than or equal to and 'low' as less than a 4% Initial Concentration. Search methods For the updated review, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (1950 to February 2016), EMBASE (1980 to February 2016), Latin American Caribbean Health Sciences Literature (LILACS) (1982 to February 2016) and the Institute for Scientific Information (ISI) Web of Science (1946 to February 2016). We also searched the reference lists of relevant articles and conference proceedings and contacted the authors of included trials. The original search was run in September 2011. Selection criteria We sought all published and unpublished, randomized controlled trials comparing high versus low Initial sevoflurane Concentration inhalational induction. Our primary outcomes included two measures of anaesthesia (time to loss of the eyelash reflex (LOER) and time until a weighted object held in the patient's hand was dropped), time to successful insertion of a laryngeal mask airway (LMA) and time to endotracheal intubation. Other outcomes were complications of the technique. Data collection and analysis We used standardized methods for conducting a systematic review as described in the Cochrane Handbook for Systematic Reviews of Interventions. Two review authors independently extracted details of trial methods and outcome data from reports of all trials considered eligible for inclusion. We conducted all analyses on an intention-to-treat basis, when possible. We estimated overall treatment effects by using a fixed-effect model when we found no substantial heterogeneity, whereas we applied the random-effects model in the presence of considerable heterogeneity. Main results We reran the searches and included one new study (100 participants) in this updated review. In total, we included 11 studies with 829 participants, although most analyses were based on data from fewer participants and evidence of low quality. We noted substantial heterogeneity in the included trials. Thus, our results should be read with caution. It was not possible to combine trials for the primary outcome (LOER), but individual trials reported faster induction times (typically 24 to 82 seconds faster, 41 seconds (31.37 to 50.62)) with high Initial Concentration sevoflurane (six studies, 443 participants, low-quality evidence). Apnoea appeared to be more common in the high Initial Concentration sevoflurane group (risk ratio (RR) 3.14, 95% confidence interval (CI) 1.72 to 5.7, two studies, 160 participants, low-quality evidence). We found no evidence of differences between the two groups in the incidence of cough (odds ratio (OR) 1.23, 95% CI 0.53 to 2.81, eight studies, 589 participants, low-quality evidence), laryngospasm (OR 1.59, 95% CI 0.16 to 15.9, seven studies, 588 participants, low-quality evidence), breath holding (OR 1.16, 95% CI 0.47 to 2.83, five studies, 389 participants, low-quality evidence), patient movement (RR 1.14, 95% CI 0.69 to 1.89, five studies, 445 participants, low-quality evidence) or bradycardia (OR 0.8, 95% CI 0.22 to 2.88, three studies, 199 participants, low-quality evidence), and the overall incidence of complications was low. Authors' conclusions A high Initial Concentration sevoflurane technique probably offers more rapid induction of anaesthesia and a similar rate of complications, except for apnoea, which may be more common with a high Initial Concentration. However, this conclusion is not definitive because the included studies provided evidence of low quality.
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High Initial Concentration versus low Initial Concentration sevoflurane for inhalational induction of anaesthesia.
The Cochrane database of systematic reviews, 2012Co-Authors: Polpun Boonmak, Suhattaya Boonmak, Porjai PattanittumAbstract:Sevoflurane induction for general anaesthesia has been reported to be safe, reliable and well accepted by patients. Sevoflurane induction uses either low or high Initial Concentrations. The low Initial Concentration technique involves Initially administering a low Concentration then gradually increasing the dose until the patient is anaesthetized. The high Initial Concentration technique involves administering high Concentrations from the beginning, continuing until the patient is anaesthetized. We aimed to compare the induction times and complications between high and low Initial Concentration sevoflurane induction in patients who received inhalational induction for general anaesthesia. We defined 'high' as greater and 'low' as less than a 4% Initial Concentration. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 9); MEDLINE (1950 to September 2011); EMBASE (1980 to September 2011); LILACS (1982 to September 2011) and ISI Web of Science (1946 to September 2011). We also searched the reference lists of relevant articles, conference proceedings; and contacted the authors of included trials. We sought all published and unpublished, randomized controlled trials comparing high versus low Initial sevoflurane Concentration inhalational induction. Our primary outcomes were two measures of anaesthesia (time to loss of the eyelash reflex (LOER) and time until a weighted object held in the patient's hand was dropped), time to successful insertion of a laryngeal mask airway (LMA), and time to endotracheal intubation. Other outcomes were complications of the technique. We used the standardized methods for conducting a systematic review as described by the Cochrane Handbook for Systematic Reviews of Interventions. Two authors independently extracted details of trial methodology and outcome data from reports of all trials considered eligible for inclusion. All analyses were made on an intention-to-treat basis, where possible. The overall treatment effects were estimated by using a fixed-effect model when there was no substantial heterogeneity, whereas the random-effects model was applied in the presence of considerable heterogeneity. We used data from 10 studies with 729 participants in the review, though most analyses were based on data from fewer participants. There was substantial heterogeneity in the trials. Thus, our results should be read with caution. It was not possible to combine the trials for the primary outcome (LOER) but individual trials found faster induction times (typically 24 to 82 seconds faster) with high Initial Concentration sevoflurane. Apnoea appeared to be more common in the high Initial Concentration sevoflurane group (two trials,160 participants). There was no evidence of a difference in the incidence of cough, laryngospasm, breath holding, bradycardia, salivation and hypotension between the two groups, with the overall incidence of complications being low. A high Initial Concentration sevoflurane technique probably offers more rapid induction of anaesthesia and a similar rate of complications except for apnoea, which may be more common with a high Initial Concentration. However, this conclusion is not definitive.
Jesús C. Echeverría - One of the best experts on this subject based on the ideXlab platform.
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simultaneous effect of ph temperature ionic strength and Initial Concentration on the retention of lead on illite
Applied Clay Science, 2005Co-Authors: Jesús C. Echeverría, Irantzu Zarranz, Juncal Estella, Julián GarridoAbstract:Abstract Sorption of metal ions by clay minerals is a complex process involving different mechanisms, and controlled by different variables that can interact. The aim of this work was to study the retention mechanisms of Pb 2+ ions on illite. We obtained Pb 2+ sorption isotherms at constant pH, sorption edges as a function of pH, sorption isotherms at 5, 25 and 45 °C (pH = 5.5), and response surfaces of the simultaneous effect of pH, Initial Concentration, ionic strength, and temperature on the retention of Pb 2+ ions on illite. Surface topography and atomic composition of illite samples doped with Pb 2+ were studied by scanning electron microscopy and X-ray fluorescence microanalysis. Below pH 4.5, sorption of Pb 2+ ions on illite is via ion exchange with H 3 O + and Na + ions that saturated the exchange sites, where the exchange with Na + is the main mechanism between pH 3.5 and 4.5. Al 3 + ions whose Concentration in solution increases with decreasing pH can also compete with Pb 2+ ions. For pH above 5.0, proton stoichiometry was higher than 1.0, and the effect of ionic strength on the amount of Pb 2+ retained decreased with pH; in fact, at pH 6.8, the amount adsorbed was practically 100% and independent of ionic strength. The pronounced decrease in the intensity of the OH-stretching band for Pb–illite sample at pH 7.0 suggests that Pb 2+ ions had lost the inner hydration sphere. The analysis of images obtained by SEM from 3 mM Pb 2+ solutions with and without illite showed particles with the same morphology, which indicate a homogenous lead precipitation from the solution. For pH values higher than 4.5, increase in the temperature favored the retention of Pb 2+ ions.
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Simultaneous effect of pH, temperature, ionic strength, and Initial Concentration on the retention of Ni on illite
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003Co-Authors: Jesús C. Echeverría, J. Indurain, E. Churio, Julián GarridoAbstract:Abstract Adsorption of metals by clay minerals is a complex process involving different mechanisms, and controlled by different variables that can interact. The aim of this work was to study the simultaneous effect of pH, Initial Concentration, ionic strength, and temperature on the retention of Ni on illite by Response Surface Methodology. As fitting and analyzing response surfaces is greatly facilitated by the proper choice of experimental conditions, we previously obtained Ni adsorption isotherms at constant pH and adsorption edges as a function of pH. Adsorption isotherms at 15, 25 and 35 °C (pH 7.5) were performed to deduce thermodynamic parameters. Surface topography and atomic composition of illite samples doped with Ni were studied by scanning electron microscopy and X-ray fluorescence microanalysis. Below pH 7, ionic strength had the largest effect on Ni adsorption illite suggesting that ion exchange with H 3 O + and Na(I) ions that saturated the exchange sites was the main retention mechanism; Al(III) ions whose Concentration in solution increases with decreasing pH can also compete with Ni(II) ions. For pH values higher than 7, the amount of Ni retained increased with the Initial Concentration, pH and temperature; the effect of ionic strength on the amount of Ni(II) retained decreased with pH, being negligible at pH 8. Precipitation was nucleated by illite surfaces; as Ni percentage in illite surface increased, Si percentage decreased. These facts are compatible with a more specific process involving hydrolyzed species, where nickel can associate with illite as an inner sphere complex.
Polpun Boonmak - One of the best experts on this subject based on the ideXlab platform.
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The Cochrane Library - High Initial Concentration versus low Initial Concentration sevoflurane for inhalational induction of anaesthesia
The Cochrane database of systematic reviews, 2016Co-Authors: Polpun Boonmak, Suhattaya Boonmak, Porjai PattanittumAbstract:Background Sevoflurane induction for general anaesthesia has been reported to be safe, reliable and well accepted by patients. Sevoflurane induction uses either low or high Initial Concentrations. The low Initial Concentration technique involves Initially administering a low Concentration of sevoflurane and gradually increasing the Concentration of the dose until the patient is anaesthetized. The high Initial Concentration technique involves administering high Concentrations from the beginning, then continuing with those high doses until the patient is anaesthetized. This review was originally published in 2013 and has been updated in 2016. Objectives We aimed to compare induction times and complication rates between high and low Initial Concentration sevoflurane anaesthetic induction techniques in adults and children who received inhalational induction for general anaesthesia. We defined 'high' as greater than or equal to and 'low' as less than a 4% Initial Concentration. Search methods For the updated review, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (1950 to February 2016), EMBASE (1980 to February 2016), Latin American Caribbean Health Sciences Literature (LILACS) (1982 to February 2016) and the Institute for Scientific Information (ISI) Web of Science (1946 to February 2016). We also searched the reference lists of relevant articles and conference proceedings and contacted the authors of included trials. The original search was run in September 2011. Selection criteria We sought all published and unpublished, randomized controlled trials comparing high versus low Initial sevoflurane Concentration inhalational induction. Our primary outcomes included two measures of anaesthesia (time to loss of the eyelash reflex (LOER) and time until a weighted object held in the patient's hand was dropped), time to successful insertion of a laryngeal mask airway (LMA) and time to endotracheal intubation. Other outcomes were complications of the technique. Data collection and analysis We used standardized methods for conducting a systematic review as described in the Cochrane Handbook for Systematic Reviews of Interventions. Two review authors independently extracted details of trial methods and outcome data from reports of all trials considered eligible for inclusion. We conducted all analyses on an intention-to-treat basis, when possible. We estimated overall treatment effects by using a fixed-effect model when we found no substantial heterogeneity, whereas we applied the random-effects model in the presence of considerable heterogeneity. Main results We reran the searches and included one new study (100 participants) in this updated review. In total, we included 11 studies with 829 participants, although most analyses were based on data from fewer participants and evidence of low quality. We noted substantial heterogeneity in the included trials. Thus, our results should be read with caution. It was not possible to combine trials for the primary outcome (LOER), but individual trials reported faster induction times (typically 24 to 82 seconds faster, 41 seconds (31.37 to 50.62)) with high Initial Concentration sevoflurane (six studies, 443 participants, low-quality evidence). Apnoea appeared to be more common in the high Initial Concentration sevoflurane group (risk ratio (RR) 3.14, 95% confidence interval (CI) 1.72 to 5.7, two studies, 160 participants, low-quality evidence). We found no evidence of differences between the two groups in the incidence of cough (odds ratio (OR) 1.23, 95% CI 0.53 to 2.81, eight studies, 589 participants, low-quality evidence), laryngospasm (OR 1.59, 95% CI 0.16 to 15.9, seven studies, 588 participants, low-quality evidence), breath holding (OR 1.16, 95% CI 0.47 to 2.83, five studies, 389 participants, low-quality evidence), patient movement (RR 1.14, 95% CI 0.69 to 1.89, five studies, 445 participants, low-quality evidence) or bradycardia (OR 0.8, 95% CI 0.22 to 2.88, three studies, 199 participants, low-quality evidence), and the overall incidence of complications was low. Authors' conclusions A high Initial Concentration sevoflurane technique probably offers more rapid induction of anaesthesia and a similar rate of complications, except for apnoea, which may be more common with a high Initial Concentration. However, this conclusion is not definitive because the included studies provided evidence of low quality.
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High Initial Concentration versus low Initial Concentration sevoflurane for inhalational induction of anaesthesia.
The Cochrane database of systematic reviews, 2012Co-Authors: Polpun Boonmak, Suhattaya Boonmak, Porjai PattanittumAbstract:Sevoflurane induction for general anaesthesia has been reported to be safe, reliable and well accepted by patients. Sevoflurane induction uses either low or high Initial Concentrations. The low Initial Concentration technique involves Initially administering a low Concentration then gradually increasing the dose until the patient is anaesthetized. The high Initial Concentration technique involves administering high Concentrations from the beginning, continuing until the patient is anaesthetized. We aimed to compare the induction times and complications between high and low Initial Concentration sevoflurane induction in patients who received inhalational induction for general anaesthesia. We defined 'high' as greater and 'low' as less than a 4% Initial Concentration. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 9); MEDLINE (1950 to September 2011); EMBASE (1980 to September 2011); LILACS (1982 to September 2011) and ISI Web of Science (1946 to September 2011). We also searched the reference lists of relevant articles, conference proceedings; and contacted the authors of included trials. We sought all published and unpublished, randomized controlled trials comparing high versus low Initial sevoflurane Concentration inhalational induction. Our primary outcomes were two measures of anaesthesia (time to loss of the eyelash reflex (LOER) and time until a weighted object held in the patient's hand was dropped), time to successful insertion of a laryngeal mask airway (LMA), and time to endotracheal intubation. Other outcomes were complications of the technique. We used the standardized methods for conducting a systematic review as described by the Cochrane Handbook for Systematic Reviews of Interventions. Two authors independently extracted details of trial methodology and outcome data from reports of all trials considered eligible for inclusion. All analyses were made on an intention-to-treat basis, where possible. The overall treatment effects were estimated by using a fixed-effect model when there was no substantial heterogeneity, whereas the random-effects model was applied in the presence of considerable heterogeneity. We used data from 10 studies with 729 participants in the review, though most analyses were based on data from fewer participants. There was substantial heterogeneity in the trials. Thus, our results should be read with caution. It was not possible to combine the trials for the primary outcome (LOER) but individual trials found faster induction times (typically 24 to 82 seconds faster) with high Initial Concentration sevoflurane. Apnoea appeared to be more common in the high Initial Concentration sevoflurane group (two trials,160 participants). There was no evidence of a difference in the incidence of cough, laryngospasm, breath holding, bradycardia, salivation and hypotension between the two groups, with the overall incidence of complications being low. A high Initial Concentration sevoflurane technique probably offers more rapid induction of anaesthesia and a similar rate of complications except for apnoea, which may be more common with a high Initial Concentration. However, this conclusion is not definitive.
Nicolas Marmier - One of the best experts on this subject based on the ideXlab platform.
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sorption of cr vi onto natural iron and aluminum oxy hydroxides effects of ph ionic strength and Initial Concentration
Journal of Hazardous Materials, 2010Co-Authors: Omar Ajouyed, Charlotte Hurel, Mohammed Ammari, Laila Ben Allal, Nicolas MarmierAbstract:The aim of this work is to study the performances of removal of hexavalent chromium from aqueous solution by three different oxy-hydroxides: hematite, goethite and α-alumina. Batch experiments were conducted to measure the effects on adsorption of Cr(VI) of different parameters such as pH of the medium, ionic strength, and Initial Concentration. Results showed that the adsorption of Cr(VI) depends strongly on the pH, but is independent of ionic strength for hematite and goethite. For α-alumina, adsorption is strongly dependent on pH values and ionic strength. Equilibrium studies showed that Cr(VI) had a high affinity in an acidic medium, but decreased as solution pH increased. Equilibrium isotherms were measured experimentally. Results were analyzed by the Langmuir and Freundlich equations using linearized correlation coefficient at room temperature. The characteristic parameters for each isotherm have been determined. Langmuir equation was found to fit the equilibrium data for Cr(VI) adsorption.
