Roberta K. Rodrigues  Lucas A. S. Silva  Gabriel G. Vargas  Bruno V. Loureiro 《Journal of surfactants and detergents》2020,23(1):21-40

This study describes the effects of wormlike micelles formed by the commercial surfactants tallowalkylamidopropyl dimethylamine oxide (Aromox APA-TW) and oleyl methyl bis(2-hydroxyethyl) ammonium chloride (Ethoquad O/12) as drag reducers. Ethoquad O/12 is immune to degradation by heat and microorganisms. Conversely, Aromox APA-TW is biodegradable in the environment, and its susceptibility to heat-induced degradation was previously assessed. This work considers the effects of temperature, salt, and time on the drag-reduction capacity (in different Reynolds number) of wormlike micelles of these two surfactants. Wormlike micelles formed by Aromox APA-TW are able to reduce drag at higher temperatures compared to wormlike micelles formed by Ethoquad O/12. However, Aromox APA-TW can degrade after being heated to 80 °C and also after storage of the wormlike micelle solutions. Ethoquad O/12 does not undergo degradation after being heated or stored. These surfactants have the potential to be used as additives in industrial operations, as the wormlike micelles formed are able to reduce drag in systems with long pumping distances or recirculation, even in solutions with high salt concentrations (brine) and high temperatures.  相似文献   

    

Dr. Andria V. Rodrigues  Prof. Dr. Dean J. Tantillo  Dr. Aindrila Mukhopadhyay  Prof. Dr. Jay D. Keasling  Dr. Harry R. Beller 《Chembiochem : a European journal of chemical biology》2020,21(5):663-671

We recently reported the discovery of phenylacetate decarboxylase (PhdB), representing one of only ten glycyl-radical-enzyme reaction types known, and a promising biotechnological tool for first-time biochemical synthesis of toluene from renewable resources. Here, we used experimental and computational data to evaluate the plausibility of three candidate PhdB mechanisms, involving either attack at the phenylacetate methylene carbon or carboxyl group [via H-atom abstraction from COOH or single-electron oxidation of COO⁻ (Kolbe-type decarboxylation)]. In vitro experimental data included assays with F-labeled phenylacetate, kinetic studies, and tests with site-directed PhdB mutants; computational data involved estimation of reaction energetics using density functional theory (DFT). The DFT results indicated that all three mechanisms are thermodynamically challenging (beyond the range of many known enzymes in terms of endergonicity or activation energy barrier), reflecting the formidable demands on PhdB for catalysis of this reaction. Evidence that PhdB was able to bind α,α-difluorophenylacetate but was unable to catalyze its decarboxylation supported the enzyme's abstraction of a methylene H atom. Diminished activity of H327A and Y691F mutants was consistent with proposed proton donor roles for His327 and Tyr691. Collectively, these and other data most strongly support PhdB attack at the methylene carbon.  相似文献   

    

Dbora Drummond Hauss Monteiro  Henrique Limboro  Rodrigo Guimares Porto  Allyson Nogueira Moreira  Wagner Nunes Rodrigues  Cludia Silami de Magalhes 《Microscopy research and technique》2020,83(6):597-603

The MeX? software is a useful tool for tridimensional data collection for surface evaluation and could be relevant to evaluate the same specimen in different phases of the study, assuming repeated measures of dental enamel roughness. The aim of this study was to evaluate the influence of sample metallization for dental enamel roughness analysis with 3D images reconstructed using MeX? software from Scanning Electron Microscopy (SEM) images. The influence of 74.98% (%mol/mol) argon?oxygen plasma for carbon layer removal on surface roughness of the metallized specimen was also evaluated. Dental enamel specimens were prepared for SEM analysis with and without carbon metallization using conventional or environmental modes. Argon?oxygen plasma for carbon layer removal was used and surface roughness was re‐evaluated. Roughness obtained by SEM and MeX? reconstructed images, with or without metallization, did not differ. No significant alteration on surface roughness after carbon layer removal using plasma was found. SEM baseline evaluation using conventional mode without sample preparation and in environmental mode were not comparable. Roughness of enamel 3D images reconstructed with MeX? software from SEM images, with or without metallization was similar. The 74.98% (%mol/mol) argon?oxygen plasma removed the carbon layer with no effect on enamel roughness.  相似文献   

    

Denise Maria Loureiro Contente  Rayanne Rocha Pereira  Antonio Manoel Cruz Rodrigues  Edilene Oliveira da Silva  Roseane Maria Ribeiro-Costa  José Otavio Carrera Silva-Júnior 《化学工程与技术》2020,43(7):1424-1432

Nanoemulsion-based acai oil was obtained by the phase inversion method using two nonionic surfactants, Ceteareth-20 (Brij™ CS20) and polyoxyethylene-hydrogenated castor oil (Croduret™ 50), with the concentration of each surfactant varying from 7 to 10 %. The formulation with 10 % Brij CS20 presented the best values for droplet size, zeta potential, and polydispersity index (PDI). Ketoconazole was incorporated into this formulation, with an encapsulation efficiency of 98.31 % and equally good zeta potential, droplet size, and PDI, and spherical shape when observed by transmission electron microscopy. Overall, nanoemulsions of acai oil proved to be a good vehicle for imidazole antifungals such as ketoconazole.  相似文献   

    

Durjoy Baidya  Marco Antonio Rodrigues de Brito  Seyed Ali Ghoreishi-Madiseh 《矿业科学技术学报(英文版)》2020,30(4):517-523

Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter. The cold fresh air of those remote areas can be as severe as -40 ℃ and commonly needs to be heated to around +3 ℃. This extensive amount of heating is usually provided by employing large-size air heaters,fueled by diesel, propane, natural gas, or heavy oil, leading to high energy costs and large carbon footprints. At the same time, the thermal energy content of a diesel generator sets(gen-sets) exhaust is known to be one-third of the total heating value of its combusted fuel. Exhaust heat recovery from diesel gen-sets is a growing technology that seeks to mitigate the energy costs by capturing and redirecting this commonly rejected exhaust heat to other applications such as space heating or pre-heating of the mine intake air. The present study investigated the possibility of employing a simple system based on off-theshelf heat exchanger technology, which can recover the waste heat from the exhaust of the power generation units(diesel gen-sets) in an off-grid, cold, remote mine in Canada for heating of the mine intake air. Data from a real mine was used for the analysis along with environmental data of three different location-scenarios with distinct climates. After developing a thermodynamic model, the heat savings were calculated, and an economic feasibility evaluation was performed. The proposed system was found highly viable with annual savings of up to C$6.7 million and capable enough to provide an average of around 75% of the heating demand for mine intake air, leading to a payback period of about eleven months or less for all scenarios. Deployment of seasonal thermal energy storage has also been recommended to mitigate the mismatch between supply and demand, mainly in summertime, possibly allowing the system to eliminate fuel costs for intake air heating.  相似文献   

    

Paulo Carmo  Ana M. Ribeiro  Alírio E. Rodrigues  Alexandre Ferreira 《American Institute of Chemical Engineers》2020,66(5):e16899

This work aims at developing an efficient and feasible adsorption-based separation process for the separation of vinyl chloride and nitrogen, on activated carbon, by employing a multitubular packed bed geometry, with adsorbent material inside the tubes. Using this geometry, a 2-dimensional mathematical model of a temperature pressure swing adsorption process was used to developed a 6-step three multitubular adsorbers system capable of separating and purifying an industrial scale gas stream of a 40:60% (v/v) vinyl chloride/nitrogen mixture into a 95% (v/v) vinyl chloride stream and a nitrogen stream with a vinyl chloride limit concentration of 8 ppm (w/w). The process reported energy consumption of 4.88 × 10⁶ J/kg_VCM and recovery capacity of 24.35 kg_VCM/(m³_unit h). The multitubular geometry enabled the use of lower adsorbent loads, shorter cycle times, and lower regeneration temperatures. An equivalent 1-dimensional model has also shown to satisfactorily estimate the performance of the current equipment.  相似文献   

    

Fernanda Palladino  Rita C L B Rodrigues  Raquel M Cadete  Katharina O Barros  Carlos A Rosa 《Biofuels, Bioproducts and Biorefining》2021,15(3):690-702

This study aimed to screen the xylitol-producing strains of Cyberlindnera xylosilytica and Wickerhamomyces rabaulensis for the bioconversion of the hemicellulosic fraction of sugarcane bagasse. Among the 16 strains tested, two of each species (C. xylosilytica UFMG-CM-Y309 and UFMG-CM-Y409, and W. rabaulensis UFMG-CM-Y3716 and UFMG-CM-Y3747) were selected on the basis of xylitol yield (Y_p/s) and xylitol volumetric productivity (Q_p) in YPX broth (yeast extract, 10 g L⁻¹; peptone, 20 g L⁻¹; and d -xylose, 60 g L⁻¹). These strains were cultivated in sugarcane bagasse hemicellulosic hydrolysate (SCHH) supplemented with ammonium sulfate, rice bran extract, and yeast extract. The xylitol yield was the highest in the strain C. xylosilytica UFMG-CM-Y-309 with a production of 14.06 g L⁻¹; xylitol yield, 0.63 g g⁻¹; xylitol volumetric productivity, 0.20 g L⁻¹ h⁻¹. Xylitol yields ranged from 14% to 74% above those of other xylitol-production yeast species. This work demonstrates the potential of biotechnological application of these yeasts for xylitol production. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd  相似文献   

    

Maria Micheline Teixeira Lopes  Maria do Carmo Passos Rodrigues  Ana Maria Souza de Araújo 《Journal of food science》2018,83(3):798-803

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Ruly Terán‐Hilares  Rosana Chirinos  Romina Pedreschi  David Campos 《Journal of food process engineering》2018,41(1)

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Daniela Maria Rodrigues  Bethania Vilela Eiras Veríssimo  Ana Carla Marques Pinheiro  Vanessa Rios de Souza 《Journal of Food Processing and Preservation》2018,42(6)

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