Reverse Hierarchy of Alkane Adsorption in Metal–Organic Frameworks (MOFs) Revealed by Immersion Calorimetry

Immersion calorimetry into liquids of different dimensions is a powerful tool to learn about the pore size and shape in nanoporous solids. In general, in the absence of specific interactions with the solid surface, the accessibility of the liquid probe molecule to the inner porosity and the associated enthalpy value decreases with an increase in its kinetic diameter (bulkier molecules have lower accessibility and packing density). Although this is true for the majority of solids (e.g., activated carbons and zeolites), this study anticipates that this is not straightforward in the specific case of metal–organic frameworks (MOFs). The evaluation of different hydrocarbons and their derivatives reveals the presence of reverse selectivity for C6 isomers (2,2-dimethylbutane > 2-methylpentane > n-hexane) in UiO-66 and HKUST-1, whereas size exclusion effects take place in ZIF-8. The immersion calorimetric findings have been compared with vapor adsorption isotherms and computational studies. Monte Carlo simulations suggest that the reverse selectivity in UiO-66 is attributed to the strong confinement of the dibranched hydrocarbons in the small tetragonal cages, whereas the presence of strong interactions with the open metal sites accounts for the preferential adsorption in HKUST-1. These results open the gate toward the application of immersion calorimetry for the prescreening of MOFs to identify in an easy, fast and reliable way interesting characteristics and/or properties such as separation ability, reversed hierarchy, pore-window size, presence of unsaturated metal sites, molecular accessibility, and so on.Authors would like to acknowledge financial support from MINECO (MAT2016-80285-p), Generalitat Valenciana (PROMETEOII/2014/004) and H2020 (MSCA-RISE-2016/NanoMed Project). P.Z.M. is grateful for start-up funds from the University of Sheffield

Dexamethasone Treatment Reverses Cognitive Impairment but Increases Brain Oxidative Stress in Rats Submitted to Pneumococcal Meningitis

Pneumococcal meningitis is associated with a significant mortality rate and neurologic sequelae. The animals received either 10 μL of saline or a S. pneumoniae suspension and were randomized into different groups: sham: placebo with dexamethasone 0.7 mg/kg/1 day; placebo with dexamethasone 0.2 mg/kg/7 days; meningitis groups: dexamethasone 0.7 mg/kg/1 day and dexamethasone 0.2 mg/kg/7 days. Ten days after induction we evaluated memory and oxidative stress parameters in hippocampus and cortex. In the step-down inhibitory avoidance task, we observed memory impairment in the meningitis group with dexamethasone 0.2 mg/kg/7 days. The lipid peroxidation was increased in hippocampus in the meningitis groups with dexamethasone and in cortex only in the meningitis group with dexamethasone 0.2 mg/kg/7 days. The protein carbonyl was increased in hippocampus in the meningitis groups with dexamethasone and in cortex in the meningitis groups with and without dexamethasone. There was a decrease in the proteins integrity in hippocampus in all groups receiving treatment with dexamethasone and in cortex in all groups with dexamethasone (0.7 mg/kg/1 day). The mitochondrial superoxide was increased in the hippocampus and cortex in the meningitis group with dexamethasone 0.2 mg/kg/7 days. Our findings demonstrate that dexamethasone reverted cognitive impairment but increased brain oxidative stress in hippocampus and cortex in Wistar rats ten days after pneumococcal meningitis induction

Tailoring the adsorption behavior of bone char for heavy metal removal from aqueous solution

This paper evaluates the pyrolysis conditions applied during the synthesis of bovine bone char and the effect of these parameters in its adsorption properties for heavy metal removal from aqueous solution at batch reactors. The synthesis route has been analyzed in detail and the surface interactions involved in the adsorption process has been studied and discussed using different characterization techniques, given a special emphasis on X-ray photoelectron spectroscopy (XPS) analysis. A proper selection of the pyrolysis conditions improved the metal uptake of bone chars by 143% where the adsorption capacities ranged from 68.3 up to 119.4 mg/g. The removal performance followed the trend Cd2+ > Zn2+ > Ni2+. However, the multicomponent removal of Zn2+, Cd2+, and Ni2+ ions in both binary and ternary mixtures was a strong antagonistic adsorption process. XPS analysis confirmed that the ion exchange between the calcium, from the hydroxyapatite structure of bone char, and the heavy metals in solution played an important role in the adsorption process. These findings are useful to enhance the efficacy of heavy metal removal from aqueous solution using bone char

A new synthesis route for bone chars using CO2 atmosphere and their application as fluoride adsorbents

This study describes a new synthesis route for bone chars using a CO2 atmosphere and their behavior as adsorbent for fluoride removal from water. Specifically, we have performed a detailed analysis of the adsorption properties of bone char samples obtained at different carbonization conditions and a comparative study with samples of bone char obtained via pyrolysis under nitrogen. Experimental results show that the nature of the gas atmosphere (CO2 versus N2) and the carbonization temperature play a major role to achieve an effective bone char for water defluoridation. In particular, the best adsorption properties of bone char for fluoride removal are obtained with those samples synthesized at 700 °C. Carbonization temperatures above 700 °C under CO2 atmosphere cause the dehydroxylation of the hydroxyapatite in the bone char, thus reducing its fluoride adsorption capacity. The maximum fluoride adsorption capacity for the bone char obtained in this study under CO2 atmosphere (i.e., 5.92 mg/g) is higher than those reported for commercial bone chars.Authors acknowledge the financial support provided by CONACYT, DGEST, Instituto Tecnológico de Aguascalientes and Universidad de Alicante

Physico-chemical characterization of metal-doped bone chars and their adsorption behavior for water defluoridation

New bone chars for fluoride adsorption from drinking water have been synthetized via metallic doping using aluminum and iron salts. A detailed statistical analysis of the metal doping process using the signal-to-noise ratios from Taguchi's experimental designs and its impact on the fluoride adsorption properties of modified bone chars have been performed. The best conditions, including the proper metallic salt, for metal doping were identified to improve the fluoride uptakes of modified bone chars. Results showed that the fluoride adsorption properties of bone chars can be enhanced up to 600% using aluminum sulfate for the surface modification. This aluminum-based adsorbent showed an adsorption capacity of 31 mg/g, which outperformed the fluoride uptakes reported for several adsorbents. Surface interactions involved in the defluoridation process were established using FTIR, DRX and XPS analysis. Defluoridation using the metal-doped bone chars occurred via an ion exchange process between fluoride ions and the hydroxyl groups on the adsorbent surface, whereas the Al(OH)xFy, FexFy, and CaF2 interactions could play also an important role in the removal process. These metal-doped adsorbents anticipate a promising behavior in water treatment, especially in developing countries where the efficiency – cost tradeoff is crucial for implementing new defluoridation technologies.Authors acknowledge the financial support provided by CONA-CYT, DGEST, Instituto Tecnológico de Aguascalientes (Mexico), Universidad de Alicante (Spain) and MINECO (Projects PCIN-2013-057 and MAT2013- 45008-P)

A implementação da telenfermagem no período pós-operatório mediato e tardio: protocolo de revisão de escopo

Este é um protocolo de revisão de escopo que terá por objetivo mapear as características do processo de implementação da telenfermagem no pós-operatório mediato e tardio de todas as especialidades cirúrgicas. A telenfermagem é uma tecnologia muito utilizada em diversas áreas do cuidado. Em uma leitura preliminar, evidências internacionais apontam que diversos benefícios puderam ser experimentados pelos pacientes cirúrgicos com a implementação dessa prática pelos enfermeiros. Desse modo acredita-se que um mapeamento da literatura acerca deste assunto irá fomentar cada vez mais o interesse da população, dos profissionais enfermeiros e gestores por essa modalidade de cuidado inovadora, que ultrapassa barreiras físicas e geográficas, promovendo cada vez mais um cuidado igualitário e universal, assim como propõe o ministério da saúde do Brasil. É importante ressaltar que o arquivo referente a este protocolo foi atualizado devido a necessidade de incluir novos autores que participaram na elaboração da estratégia de busca para pesquisa. Também foi retirado um quadro referente as estratégias de busca que ainda serão utilizadas na segunda etapa de busca, e ainda houve a inclusão de duas citações que faltavam na lista de referências

Attenuation of cognitive impairment by the nonbacteriolytic antibiotic daptomycin in Wistar rats submitted to pneumococcal meningitis

BACKGROUND: Streptococcus pneumoniae is associated with neurologic sequels, such as, seizures, sensory-motor deficits, hearing loss, learning and memory impairment, which can occur in approximately 30 to 52% of surviving patients. Neuronal damage can be caused by intense inflammatory reaction and direct effects of the bacteria virulence factors. The aim of the present study was to evaluate the effects of the nonbacteriolytic antibiotic daptomycin versus ceftriaxone on behavioral parameters in adult Wistar rats submitted to pneumococcal meningitis. RESULTS: Ten days after induction we verified that the meningitis group with daptomycin treatment showed retention of aversive memory; it presented memory of the object recognition at short term and long term. In continuous multiple-trials step-down inhibitory avoidance task the meningitis group with ceftriaxone treatment required approximately two times more stimulus to reach the acquisition criterion when compared with meningitis group with daptomycin treatment. However, in the habituation memory test there were no differences in the number of crossings and rearings in training and task sessions demonstrating habituation impairment to the environment task in both meningitis groups. CONCLUSIONS: The evidence of the present study shows the potential alternative of the treatment with daptomycin in preventing learning and memory impairments caused by pneumococcal meningitis. Further investigations are necessary to provide support for evaluation of daptomycin as an alternative treatment of bacterial meningitis

Preparation and investigation of active carbons based on furfural copolymer

Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 0997–1001, June, 2018.Active carbons were synthesized from a furfural copolymer using a polyester resin as an activator. The influence of the temperature of the thermal treatment of the carbon sorbents on the weights and ash contents of the obtained materials was established. The molecular structures of the carbons were studied by NMR spectroscopy