Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt

Uso de ?ster misto de baga?o de cana na remo??o de Co2+ e Ni2+ de solu??es aquosas em batelada e em coluna de leito fixo.

Programa de P?s-Gradua??o em Engenharia Ambiental. N?cleo de Pesquisas e P?s-Gradua??o em Recursos H?dricos, Universidade Federal de Ouro Preto.Neste trabalho foi preparado um novo material derivado do baga?o da cana-de-a??car. Esse material foi aplicado como adsorvente para a remo??o de Co2+ e Ni2+ de solu??es aquosas em sistemas mono e bicomponente em batelada e em coluna de leito fixo. O material (BST) foi preparado por meio da dupla esterifica??o do baga?o de cana com os anidridos succ?nico (AS) e trimel?tico (AT) em uma rea??o de uma ?nica etapa (one-pot). Realizou-se uma etapa de triagem para a s?ntese do BST, por meio de um planejamento experimental completo do tipo 23. As vari?veis independentes investigadas foram tempo, temperatura e fra??o molar de AS (?AS). As respostas avaliadas foram capacidade de adsor??o de Co2+ e Ni2+ (qCo2+ e qNi2+), ganho de massa (pgm) e quantidade total de fun??es ?cido carbox?lico introduzidas (nT,COOH). O material BST obtido a partir das melhores condi??es de s?ntese foi caracterizado por pgm, nT,COOH, an?lise elementar de C, H e N, espectroscopia na regi?o do infravermelho com transformada de Fourier, an?lise termogravim?trica, resson?ncia magn?tica nuclear (RMN) de 13C no estado s?lido, relaxometria por RMN, difra??o de raios-X (DRX), ?rea superficial espec?fica, distribui??o de tamanho dos poros, microscopia eletr?nica de varredura (MEV), espectroscopia de energia dispersiva de raios-X (EDS) e pH do ponto de carga zero (pHPCZ). A melhor condi??o resultante do planejamento experimental (100?C, 660 min e ?AS de 0,2) produziu um material com pgm de 57,1%, nT,COOH de 4,48 mmol g-1 e qCo2+ e qNi2+ de 0,90 e 0,96 mmol g-1 , respectivamente. Os estudos de adsor??o em batelada foram realizados em diferentes tempos de contato, valores de pH e concentra??es iniciais das solu??es contendo os ?ons met?licos. O modelo de Redlich-Peterson foi o que melhor se ajustou aos dados de equil?brio para a adsor??o monocomponente em batelada de ambos os ?ons e as capacidades m?ximas de adsor??o (Qmax,est) estimadas por esse modelo foram 1,16 e 1,29 mmol g-1 para Co2+ e Ni2+ (pH 5,75, 25?C), respectivamente. O modelo RAST (Real Adsorbed Solution Theory), implementado com o modelo de isoterma de Sips, foi o que melhor se ajustou aos dados de equil?brio bicomponente em batelada para as propor??es molares 1:1 e 2:1 (pH 5,75, 25?C). Todos os modelos analisados (RAST-Sips e RAST-Langmuir) apresentaram falta de ajuste aos dados de equil?brio bicomponente em batelada para a propor??o molar 1:2. Realizou-se um estudo de dessor??o monocomponente em batelada, obtendo-se valores de efici?ncias de dessor??o e de readsor??o pr?ximos ? 100%, possibilitando a recupera??o dos ?ons met?licos e do adsorvente BST. Os valores de varia??o da entalpia padr?o de adsor??o (?adsH) obtidos por titula??o calorim?trica isot?rmica (ITC) foram de 8,03 e 6,94 kJ mol- 1 para adsor??o de Co2+ e Ni2+ , respectivamente. Foram realizados cinco ciclos sucessivos de adsor??odessor??o monocomponente em coluna de leito fixo, n?o ocorrendo redu??o significativa nos valores de Qmax,Co2+ e Qmax,Ni2+, resultando em elevadas efici?ncias de dessor??o e readsor??o em todos os ciclos. O modelo de Bohart-Adams foi o que melhor se ajustou aos dados da adsor??o monocomponente em coluna de leito fixo para ambos os ?ons met?licos com Qmax,est igual ? 0,95 e 1,02 mmol g-1 para adsor??o de Co2+ e Ni2+, respectivamente. A adsor??o bicomponente em coluna de leito fixo foi investigada por meio de um planejamento experimental de mistura. O Ni2+ apresentou maior afinidade pelos s?tios de adsor??o do BST. Os valores de Qmax,total foram pr?ximos a 1,00 mmol g-1 em todos experimentos do planejamento de mistura. O modelamento das curvas de ruptura obtidas possibilitou afirmar que os mecanismos de convec??o predominaram, com n?mero de P?clet (Pe) >> 10 e, na maioria dos sistemas estudados, a resist?ncia ? difus?o dentro das part?culas foi maior que a transfer?ncia de massa no filme, com valores do n?mero de Biot (Bi) maiores do que 30. Os experimentos para elucida??o do mecanismo de adsor??o dos ?ons Co2+ e Ni2+ no BST indicaram que a remo??o desses ?ons ocorreu por meio da troca i?nica. O estudo de adsor??o em coluna de leito fixo a partir de uma solu??o sint?tica do processo hidrometal?rgico, mostrou que a capacidade de adsor??o do Ni2+ (Qmax = 1,08 mmol g-1) (?on presente em maior concentra??o) manteve-se inalterada mesmo na presen?a dos outros ?ons, al?m de ter sido obtida uma efici?ncia de remo??o dos ?ons Co2+, Cu2+, Mg2+ e Mn2+ acima de 56%.In this study, a new material derived from sugarcane bagasse was prepared. This material was use as adsorbent for removal of Co2+ and Ni2+ from aqueous solutions in mono and bicomponent systems in batch and fixed-bed column. The material (BST) was prepared by esterification of sugarcane bagasse with succinic (SA) and trimellitic (TA) anhydrides using a one-pot synthesis method. A 23 -factorial experimental design was used to investigate the synthesis conditions of BST. The independent variables evaluated were time, temperature, and mole fraction of AS (?AS). The responses evaluated were adsorption capacities of Co2+ and Ni2+ (qCo2+ and qNi2+), weight gain (wg), and number of carboxylic acid groups (nT,COOH) introduced. The BST synthesized from the best reaction conditions was characterized by wg, nT,COOH, Fourier transform infrared spectroscopy, thermogravimetric analysis, 13C solid-state nuclear magnetic resonance (NMR) spectroscopy, NMR relaxometry, X-ray diffraction (XRD) spectroscopy, specific surface area, pore size distribution, scanning electron microscopy (SEM), energy-dispersive Xray (EDS) spectroscopy and pH of the point of zero charge (pHPCZ). The best reaction conditions obtained from the experimental design (100?C, 660 min, ?AS of 0.2) yielded a BST with wg of 57.1%, nT,COOH of 4.48 mmol g-1 and qCo2+ and qNi2+ of 0.90 and 0.96 mmol g-1, respectively. Batch adsorption studies were performed at different contact times, pH values and initial metal ion concentrations. The Redlich-Peterson model best fitted to the equilibrium data for monocomponent batch adsorption with maximum adsorption capacities (Qmax) estimated by this model of 1.16 and 1.29 mmol g- 1 for Co2+ and Ni2+, respectively. The Real Adsorbed Solution Theory (RAST) fed with Sips isotherm model best fitted to the equilibrium data for bicomponent batch adsorption for the molar ratios of 1:1 and 2:1 (pH 5.75, 25?C). All models analyzed (RAST-Sips and RAST-Langmuir) presented lack of fit for bicomponent batch adsorption for the molar ratio of 1:2. A monocomponent batch desorption study was carried out, which showed that desorption and re-adsorption efficiencies were close to 100%. This can allow the recovery of both metal ions and BST adsorbent. The values of variation in standard enthalpy of adsorption (?adsH) were obtained by isothermal titration calorimetry (ITC) and found to be 8.03 and 6.94 kJ mol-1 for Co2+ and Ni2+, respectively. Five successive monocomponent adsorption-desorption cycles in a fixed-bed column were performed. No significant decrease in Qmax,Co2+ and Qmax,Ni2+ values were observed, which was a consequence of the high desorption and re-adsorption efficiencies obtained in all cycles. The Bohart-Adams model best fitted to the monocomponent fixed-bed column adsorption data for both metal ions with Qmax,est values of 0.95 and 1.02 mmol g-1 for Co2 + and Ni2+ adsorption, respectively. Bicomponent fixed-bed column adsorption was investigated by a mixing experimental design. The Ni2+ showed higher affinity for BST adsorption sites than Co2+. The Qmax,total values were close to 1.00 mmol g-1 for all experiments. The modeling of the breakthrough curves allowed to conclude that the convection mechanisms predominated, with values of the P?clet number (Pe) >> 10 and, in the most of the studied systems, the diffusion resistance inside the particles was higher than the mass transfer through the film, with values of the Biot (Bi) number higher than 30. Experiments for elucidation of adsorption mechanism of Co2+ and Ni2+ ions on the BST indicated that the removal of these ions occurred by ion-exchange. The adsorption study in a fixed-bed column using a synthetic solution from the hydrometallurgical process showed that the adsorption capacity of Ni2+ (Qmax = 1.08 mmol g-1) (ion present in higher concentration) remained unchanged even in the presence of other ions, with a removal efficiency of Co2+, Cu2+, Mg2+ and Mn2+ ions higher than 56%

Adsorção de cátions metálicos e oxiânions em solução aquosa usando novos materiais bifuncionalizados a partir da celulose e da quitosana.

Programa de Pós-Graduação em Engenharia Ambiental. PROÁGUA, Pró-Reitoria de Pesquisa e Pós Graduação, Universidade Federal de Ouro Preto.A poluição dos recursos hídricos principalmente por ações antropogênicas vem exigindo, cada vez mais, alternativas eficazes e de baixo custo para a adequação de determinado efluente às normas de descarte vigentes. Este trabalho descreve a síntese de dois materiais bifuncionalizados inéditos, a partir da celulose e da quitosana, para adsorção de cátions metálicos e oxiânions em solução aquosa, visando à aplicação na descontaminação de recursos hídricos e efluentes industriais. A celulose foi mercerizada, succinilada e, por fim, modificada com cloreto de colina, após a formação do anidrido interno utilizando anidrido acético para a obtenção do material bifuncionalizado CM3. Já a quitosana teve seus grupamentos amina metilados e posteriormente foi modificada com dianidrido do EDTA, formando o material Q2. Os adsorventes foram caracterizados por análise elementar (CHN), espectroscopia na região do infravermelho com transformada de Fourier (FTIR), ressonância magnética nuclear de carbono 13 (RMN 13C) e ponto de carga zero (pHPCZ) . As capacidades de adsorção do material CM3 em relação ao cátion Cu(II) e ao oxiânion Cr(VI) e as capacidades de adsorção do material Q2 em relação aos cátions Co(II), Cu(II) e Ni(II) e ao oxiânion Cr(VI) foram avaliadas. A cinética e a isoterma de adsorção foram estudadas para cada sistema adsorvente-adsorvato. Os dados cinéticos obtidos experimentalmente foram modelados por regressão não linear empregando o modelo cinético de pseudo-ordem n e por regressão linear e não linear empregando os modelos de pseudoprimeira ordem e pseudossegunda ordem. Os dados experimentais referentes às isotermas foram modelados empregando as isotermas de Langmuir, de Freundlich e de Sips. Os resultados do modelamento mostraram que a regressão não linear foi mais adequada ao ajuste dos modelos supracitados aos dados experimentais e, também, para estimar os parâmetros de cada modelo. As capacidades de adsorção do material CM3 foram de 17,7mg/g para adsorção de Cu(II) e 61,7mg/g para adsorção de Cr(VI). As capacidades de adsorção do material Q2 foram 41,2mg/g para Co(II); 71,5mg/g para Cu(II); 42,5mg/g para Ni(II) e 98,3mg/g para Cr(VI).The increasing pollution of water resources mainly by human activities has required effective and low costs alternatives for the specific effluent fitting to the levels demanded by the legislation. This study describes the synthesis of two new bifunctionalized materials, from cellulose and chitosan, to adsorb metallic cations and oxyanions in aqueous solution, for application in the decontamination of water bodies and effluents from industries. The cellulose was mercerized and then succinylated. Cellulose succinate was modified with acetic anhydride groups to produce internal anhydride functional groups. Finally, these anhydride groups were reacted with choline chloride to abtain CM3 material. The amine groups from chitosan at C-2 were methylated and hydroxyl groups at C-3 and C-6 were reacted with EDTA dianhydride to obtain Q2 material. The adsorbents were characterized by elemental analysis (CHN), infrared spectroscopy with Fourier transform (FTIR), 13 carbon nuclear magnetic resonance (13C NMR) and point of zero charge (pHPCZ). The adsorption capacity of CM3 material for Cu(II) in the cation form, and Cr(VI) in the oxyanion form and the adsorption capacity of Q2 material for Co(II), Cu(II) and Ni(II) the cationic form, and Cr(VI) oxyanion form were evaluated. The adsorption kinetics and isotherms were studied for each adsorbent-adsorbate system; and the experimental data was fitted by non-linear regression of the pseudo-nth-order kinetic model and by linear and non-linear regression of the pseudo-first and the pseudo-second order kinetics models. Equilibrium data were fitted by the Langmuir, Freundlich and Sips isotherm models. Results showed that the experimental data were better fitted by non-linear regression than linear one. The adsorption capacity of the CM3 material was 17.7 mg/g for Cu(II) and 61.7mg/g for Cr(VI). The adsorption capacity of the Q2 material was 41.2 mg/g for Co(II); 71.5 mg/g for Cu(II); 42.5 mg/g for Ni(II) and 98.3 mg/g for Cr(VI)

Application of a new bifunctionalized chitosan derivative with zwitterionic characteristics for the adsorption of Cu2+, Co2+, Ni2+, and oxyanions of Cr6+ from aqueous solutions : kinetic and equilibrium aspects.

This study describes the synthesis of a new chitosan derivative (C2) with zwitterionic characteristics and its use for the removal of cationic species Cu2+, Co2+, and Ni2+ and anionic species of Cr6+ in a single aqueous solution. The new adsorbent was synthesized by quaternization of the amine group of chitosan and esterification of hydroxyl groups with EDTA dianhydride. These combined reactions gave both cationic and anionic characteristics to C2 with the release of quaternary ammonium groups and carboxylic groups. The capacity of C2 to adsorb Cu2+, Co2+, Ni2+, and oxyanions of Cr6+ was evaluated in a batch process with different contact times, pH values, and initial concentrations. Adsorption isotherms were best fitted to the Langmuir and Sips models. The maximum adsorption capacities (Qmax) of C2 for adsorption of Cu2+, Co2+, Ni2+, and Cr6+ were 0.698, 1.125, 0.725, and 1.910 mmol/g, respectively. The DadsG_ values were in the range from _20 to _28 kJ/mol. These values suggest a mixed mechanism controlling adsorption. Desorption studies using an aqueous solution consisting of 0.1 mol/L HNO3 were carried out. The reusability of the recovered C2 adsorbent after desorption was also evaluated

Synthesis and application of sugarcane bagasse cellulose mixed esters. Part I: Removal of Co2+ and Ni2+ from single spiked aqueous solutions in batch mode using sugarcane bagasse cellulose succinate phthalate

Sugarcane bagasse cellulose mixed ester succinate phthalate (SBSPh) was synthesized by a novel one-pot reaction method. The effects of temperature, time and mole fraction of succinic anhydride (χSA) on the responses weight gain (wg), number of carboxylic acid groups (nT,COOH), and adsorption capacity (q) of Co2+ and Ni2+ were evaluated by a 23 experimental design. The chemical structure of the material was elucidated by Fourier transform infrared, 13C Multiple Cross-Polarization solid-state NMR spectroscopy and 1H NMR relaxometry. The best SBSPh synthesis condition (100 °C, 11 h, χSA of 0.2) yielded a wg of 59.1%, nT,COOH of 3.41 mmol g−1, and values of qCo2+ and qNi2+ of 0.348 and 0.346 mmol g−1, respectively. The Sips model fitted better the equilibrium data, and the maximum adsorption capacities (pH 5.75 and 25 °C) estimated by this model were 0.62 and 0.53 mmol g−1 for Co2+ and Ni2+, respectively. The ΔadsH° values estimated by isothermal titration calorimetry were 8.43 and 7.79 kJ mol−1 for Co2+ and Ni2+, respectively. Desorption and re-adsorption efficiencies were evaluated by a 22 experimental design, which showed that SBSPh adsorbent can be recovered and reused without significant loss of adsorption capacity

Oxidized Renewable Materials for the Removal of Cobalt(II) and Copper(II) from Aqueous Solution Using in Batch and Fixed-Bed Column Adsorption

Batch and continuous adsorption of Co2+ and Cu2+ from aqueous solutions by oxidized sugarcane bagasse (SBox) and oxidized cellulose (Cox) were investigated. The oxidation reaction of sugarcane bagasse and cellulose was made with a mixture of H3PO4‒NaNO2 to obtain SBox and Cox, with the introduction of high number of carboxylic acid functions, 4.5 and 4.8 mmol/g, respectively. The adsorption kinetics of Co2+ and Cu2+ on SBox and Cox were modeled using two models (pseudo-first-order and pseudo-second-order) and the rate-limiting step controlling the adsorption was evaluated by Boyd and intraparticle diffusion models. The Sips and Langmuir models better fitted the isotherms with values of maximum adsorption capacity Qmax of 0.68 and 0.37 mmol/g for Co2+ and 1.20 and 0.57 mmol/g for Cu2+ adsorption on Cox and SBox, respectively. The reuse of both spent adsorbents was evaluated. Adsorption of Cu2+ and Co2+ on SBox in continuous was evaluated using a 22 factorial design with spatial time and initial metal concentration as independent variables and Qmax and effective use of the bed as responses. The breakthrough curves were very well described by the Bohart–Adams original model and the Qmax values for Co2+ and Cu2+ were 0.22 and 0.55 mmol/g. SBox confirmed to be a promising biomaterial for application on a large scale

Synthesis and application of sugarcane bagasse cellulose mixed esters. Part II : removal of Co2+ and Ni2+ from single spiked aqueous solutions in batch and continuous mode.

Sugarcane bagasse cellulose succinate trimellitate (SBST) was prepared by a one-pot synthesis method. The synthesis of this novel mixed ester was investigated by a 23-factorial design. The parameters investigated were time, temperature, and succinic anhydride mole fraction (?SA). The responses evaluated were the adsorption capacity (qCo2+ and qNi2+), weight gain (wg), and number of carboxylic acid groups (nT,COOH). 13C Multiple Cross-Polarization solid-state NMR spectroscopy, 1H NMR relaxometry, and Fourier-transform infrared spectroscopy were used to elucidate the SBST structure. The best SBST reaction conditions were 100??C, 660?min, and ?SA of 0.2, which yielded SBST with a wg of 57.1%, nT,COOH of 4.48?mmol?g?1, and qCo2+ and qNi2+ of 0.900 and 0.963?mmol?g?1, respectively. The maximum adsorption capacities (Qmax) (pH 5.75, 25??C) estimated by the Redlich-Peterson model for Co2+ and Ni2+ were 1.16 and 1.29?mmol?g?1. The ?adsH? values for Co2+ and Ni2+ adsorption obtained by isothermal titration calorimetry were 8.03 and 6.94?kJ?mol?1. Regeneration and reuse of SBST were investigated and the best conditions applied for fixed-bed column adsorption in five consecutive cycles. SBST was fully desorbed and Qmax values for Co2+ (0.95?mmol?g?1) and Ni2+ (1.02?mmol?g?1) were estimated using the Bohart-Adams model

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.13Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt