Modificação química de argilas: desafios científicos e tecnológicos para obtenção de novos produtos com maior valor agregado

Chemical modification of clays is possible due to their ion-exchange and adsorption capacities, which allows the adjustment of the physicochemical properties of the surfaces of their layers. This modification makes possible the use of clays to produce a great number of new materials, which range from coarse applications such as oil based drilling fluids to refined applications such as pharmaceutical products. This article intends to expose where there is still space for research and investment aiming at the performance improvement of clay-based materials

Use of manganese oxides recovered from spent batteries in electrocatalysis of oxygen reduction reaction in alkaline medium

The oxygen reduction reaction was studied in alkaline media using manganese oxides obtained from spent batteries as electrocatalysts. Three processes were used to recover manganese oxides from spent batteries. The particles obtained were in the range from 8 to 11 nm. The electrochemical experiments indicated a good electrocatalytic activity toward oxygen reduction using the different samples and showing approximately a direct transference of 4 electrons during the process. Even though all the processes were efficient, the best result was observed for the prepared sample using reactants of low cost.FAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)UFAB

Medidas de tensão superficial pelo método de contagem de gotas: descrição do método e experimentos com tensoativos não-iônicos etoxilados Surface tension measurement by drop counting method: method description and experiments with etoxilated non-ionic surfactants

<abstract language="eng">Surface tension knowledge of surfactants aqueous solutions is important during amphiphilic molecule manufacturing and new product development, as feedback information to handle synthesis parameters to target performance. Drop counting method is an interesting simplification of drop weight method for surface tension measurements. A simple laboratory measurement device, with capability for temperature control, was assembled to allow investigation of ethoxylated surfactants. The implementation of the method was preceded by a detailed investigation of two factors that may affect the measured surface tension: drop formation velocity and surfactant ethoxylation degree. The limitations of the method are discussed on this basis

Au–CeO2-based nanocatalysts supported on SBA-15 for preferential oxidation of carbon monoxide (PrOx-CO)

In this work, as-synthesized SBA-15 was used as a support for CeO2 and Au nanoparticles (NPs), in order to stabilize them and to promote the metal/oxide interface contact. CeO2 NPs were grown within the pores of SBA-15 using the method of successive metalorganic impregnation–decomposition cycles (IDCs), and samples with an increasing number of IDCs (x = 2, 5 and 8) were obtained. This method allowed control of the SiO2/CeO2 ratio and tailoring of samples with different crystallite sizes (2–4 nm). The (x)CeO2/S15 supports were then decorated with Au NPs through the Deposition–Precipitation (DP) method using NaOH. The DP conditions used along with the pore size limitations from each support allowed control over the Au NP size (4–9 nm). The samples were characterized by N2 physisorption, XRD, TEM, ICP-OES, XRF, DRS and Raman Spectroscopy, and for their catalytic activity for PrOx-CO. The pure supported Au-catalyst exhibited maximum CO conversion at 300 °C. The incorporation of CeO2 reduced the reaction temperature to as low as 100 °C, while the peak performance for CO conversion was observed for the catalyst containing Au and 5 IDCs of CeO2 (2.0 mol of CO2 formation per mol of Au per second at 135 °C). Further increasing the amount of CeO2 (8 IDC) resulted, however, in a decrease of the catalytic activity, resulting in a substantial reduction of the surface area and subsequent reduced access of the reaction gases (H2, CO, O2) to the active sites of the catalyst441902819036CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP407591/2016-8; 307494/2016-0; 465452/2014-0Não tem2013/22127-2; 2014/50906-

<b>Structural features and inactivation of coagulation proteases of a sulfated polysaccharidic fraction from <i>Caulerpa cupressoides</i> var. <i>lycopodium</i> (Caulerpaceae, Chlorophyta)</b> - doi: 10.4025/actascitechnol.v35i4.16709

Studies on biopolymers from macroalgae suggested sulfated polysaccharides (SPs) as research agents to investigate events related to haemostasis. Caulerpa cupressoides var. lycopodium is a marine green alga containing three SPs fractions (SP1, SP2 and SP3). SP2 had anticoagulant (in vitro) and anti- and prothrombotic (in vivo) actions; however, its effect on the coagulation system is not fully understood. This study aimed to determine the infrared (IR) spectroscopy, chemical composition (CC), elemental microanalysis (EM), molecular weight (MW) and the effect on coagulation proteases of SP2. The presence of sulfate ester, galactose-6-sulfate, uronic acid and glycoside linkages for IR spectrum; contents of sulfate (28%), total sugars (40%) and uronic acids (7.18%) for CC; and content of carbon (21.98%), sulfate (4.27%), nitrogen (1.3%) and hydrogen (4.86%) for EM were obtained. The average molecular weights of four different SPs (SP-1, SP-2, SP-3 and SP-4) subfractions from the SP2 ranged from ~ 8 to >100 kDa. SP2 was tested on coagulation proteases (thrombin and factor Xa) in the presence of antithrombin (AT) and heparin cofactor II (HCII) using human plasma, being both thrombin and factor Xa target proteases inhibited, but requiring a concentration of about 2.5-fold higher of HCII than the thrombin inactivation by AT.   </p

Time for determining the diagnosis of brain death and its relation to organ donation

This study aimed to identify the time needed for confirmation of brain death and its relation to organ donation. Quantitative, descriptive and retrospective study with 175 patients who had diagnosis of brain death completed between January and December 2013.&nbsp;The time from 11 to 20 hours (38.9%) prevailed, with average of 17.91 hours (SD 17.53).&nbsp;There was significant association between the finding of brain death diagnosis in less than 20 hours and the number of donated livers (P = 0.041). We stress the importance of speeding up the diagnosis of brain death as an important step of the donation process, in order to contribute to realization of transplants. Key words: Brain Death; Time; Directed Tissue Donation; Nursing. &nbsp