Kinetic study of ethyl octyl ether formation from ethanol and 1‐octanol on Amberlyst 70

An option to introduce bioethanol to diesel, improving at the same time its fuel quality, is by adding ethyl octyl ether (EOE). It can be obtained successfully by the dehydration reaction between ethanol and 1‐octanol over acidic ion‐exchange resins. In the present work, the kinetic study of EOE synthesis on Amberlyst 70 in the liquid phase is performed in a 20‐cm³ fixed‐bed reactor and in a 100‐cm³ batch reactor at 423–463 K and 2.5 MPa. EOE synthesis takes place together with diethyl ether (DEE) formation as main side reaction. A mechanistic kinetic model in terms of component activities is proposed for EOE synthesis (E_a=105 ± 4 kJ/mol) and for DEE formation (E_a =100 ± 5 kJ/mol). Reaction rates were highly inhibited by the adsorption of the formed water on Amberlyst 70. The inhibitor effect of water is well represented as a competitive adsorption with alcohols reactants on the catalysts surface. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2918–2928, 2014     

Innate Immune Response to SARS-CoV-2 Infection: From Cells to Soluble Mediators

The vulnerability of humankind to SARS-CoV-2 in the absence of a pre-existing immunity, the unpredictability of the infection outcome, and the high transmissibility, broad tissue tropism, and ability to exploit and subvert the immune response pose a major challenge and are likely perpetuating the COVID-19 pandemic. Nevertheless, this peculiar infectious scenario provides researchers with a unique opportunity for studying, with the latest immunological techniques and understandings, the immune response in SARS-CoV-2 naïve versus recovered subjects as well as in SARS-CoV-2 vaccinees. Interestingly, the current understanding of COVID-19 indicates that the combined action of innate immune cells, cytokines, and chemokines fine-tunes the outcome of SARS-CoV-2 infection and the related immunopathogenesis. Indeed, the emerging picture clearly shows that the excessive inflammatory response against this virus is among the main causes of disease severity in COVID-19 patients. In this review, the innate immune response to SARS-CoV-2 infection is described not only in light of its capacity to influence the adaptive immune response towards a protective phenotype but also with the intent to point out the multiple strategies exploited by SARS-CoV-2 to antagonize host antiviral response and, finally, to outline inborn errors predisposing individuals to COVID-19 disease severity.     

Natural Composite Material from Steelwool or Luffa cylindrica under Natural,Rigid and Flexible Resin

In a changing world with a high interest in new ecomaterials, natural fibers such as the steelwool or Luffa cylindriea appear in new presentations and mixing with other materials to develop better opportunities to replace synthetic fibers. This work presents a research on the use of steelwool fiber for composite materials, on the basis of the physical properties, that generate conditions of mixing with three binders （matrix） natural： the rosin, artificial hard： polyurethane resin and artificial flexible： flexible twin resin （epoxy） and finally a polyester resin to make a comparison with other major resins. A testing of compression and tension is carried out to the materials analyzed, obtaining three types of composite materials by the above mentioned binders and three proposed presentations of fiber （complete, tissue and ground）. The test tube in tension with polyester resin presented a high rigidity and a percentage of deformation of 14%, resulting in less distortion than the woven with resin polyurethane with 12% of deformation. The presentation with resin polyurethane presented greater resistance to compression, because the resin acts as a sponge absorbing the energy of charge and the join of particles is larger than the other presentations generating greater cohesion among them and avoiding its rupture easily for a load of 2,000 kg. The presentation that is least resisted was the woven in two resins in the stage of energy absorption of load where polyurethane is 800 kg and the flexible twin is 850 kg, because the form of woven fiber distribution creates spaces where there are more resin than fiber.     

Quantification of Listeria monocytogenes in minimally processed leafy vegetables using a combined method based on enrichment and 16S rRNA real-time PCR

Modern lifestyle markedly changed eating habits worldwide, with an increasing demand for ready-to-eat foods, such as minimally processed fruits and leafy greens. Packaging and storage conditions of those products may favor the growth of psychrotrophic bacteria, including the pathogen Listeria monocytogenes. In this work, minimally processed leafy vegetables samples (n = 162) from retail market from Ribeirão Preto, São Paulo, Brazil, were tested for the presence or absence of Listeria spp. by the immunoassay Listeria Rapid Test, Oxoid. Two L. monocytogenes positive and six artificially contaminated samples of minimally processed leafy vegetables were evaluated by the Most Probable Number (MPN) with detection by classical culture method and also culture method combined with real-time PCR (RTi-PCR) for 16S rRNA genes of L. monocytogenes. Positive MPN enrichment tubes were analyzed by RTi-PCR with primers specific for L. monocytogenes using the commercial preparation ABSOLUTE™ QPCR SYBR^® Green Mix (ABgene, UK). Real-time PCR assay presented good exclusivity and inclusivity results and no statistical significant difference was found in comparison with the conventional culture method (p < 0.05). Moreover, RTi-PCR was fast and easy to perform, with MPN results obtained in ca. 48 h for RTi-PCR in comparison to 7 days for conventional method.     

Food composition: a little bit of history

Data on nutrients and other food components are necessary in several sectors, such as nutrition, health, agriculture, trading and marketing. From the 17th century on, the systematic study of food composition started to be established. During the 19th century, there were many advances, such as the clarification of food energy production, the identification of nutrients and their physiologic role. Also, the first food composition tables began to emerge, finishing the century with the publication of Atwater and Wood's "The Chemical Composition of American Food Material" of the United States Department of Agriculture (USDA), in 1896. In the 20th century, the methods of analysis and the elaboration of food composition tables were improved in many countries. In 1984, INFOODS (International Network of Food Data Systems) was created. This network, linked to United Nations University (UNU) and Food and Agriculture Administration (FAO), proposed rules and created tools that brought great advances in food composition tables. Nowadays, the conscious related to food biodiversity has been amplifying the focus of food composition tables and databases. In Brazil, the Brazilian Food Composition Table (TBCA-USP), of the Brazilian Network for Food Composition Data (BRASILFOODS), since its creation in 1998, has been adopting these international patterns and is available on the Internet (http://www.fcf.usp.br/tabela), currently on the version 4.1.     

Multiwalled carbon nanotube chemically modified gold electrode for inorganic As speciation and Bi(III) determination

A chemically modified gold electrode has been conveniently prepared by binding multiwalled carbon nanotubes (MWCNTs) to which thiol functions have been tethered. The electrode has been characterized by atomic force microscopy and oxidative desorption experiments and gives excellent results for trace determination of As(III) and Bi(III) in natural and high-salinity waters, overcoming the limitation typical of solid electrodes. A mechanism for As(III) preconcentration at the electrode is proposed and supported by results obtained by two similar chemically modified electrodes (CMEs), the first one prepared with single-walled carbon nanotubes and the second one with a monolayer of (biphenyl)dimethanethiol. The performance obtained with the MWCNTs-CME largely overcomes that obtained by using other devices.