Effect of preparation method on the performance of Ni/MgOSiO2 catalysts for glycerol steam reforming

Catalysts were prepared with 10 wt% of Ni(II) and 30 wt% of MgO over commercial SiO₂, using dry (physical mixture) and wet (impregnation with different polarities solvents: ethanol and acetone) sequential processes. The characterization techniques used were energy dispersive X-ray spectroscopy, nitrogen physisorption, X-ray diffractometry, H₂ temperature-programmed reduction, X-ray diffractometry in situ with H₂, H₂ temperature-programmed desorption, and scanning electron microscopy. In order to verify activity, selectivity, and carbon deposition, the catalysts were tested in glycerol steam reforming reaction at 600 °C, for 5 h, at a 12:1 water:glycerol molar ratio. After the reactions, the catalysts were submitted to thermogravimetric analysis, X-ray diffractometry, and scanning electron microscopy, in order to characterize the carbon deposits during the catalytic process. Impregnation solvent polarity influenced the metallic dispersion and the metallic area of the catalysts, given that, the lower the polarity of the solvent, the higher the metallic dispersion and the area, and the lesser the carbon deposition during the reaction. The material that presented the best catalytic performance in terms of H₂ output and carbon deposition was the catalyst prepared with ethanol as impregnation solvent (less polar solvent), as a consequence of its greater dispersion and larger metallic area.     

IS6110 homologs are present in multiple copies in mycobacteria other than tuberculosis-causing mycobacteria

A surgical technique for safe early repair of ventricular septal rupture is described. The technique consists of exclusion of the infarcted area, septal stabilization, and remodeling of the left ventricle with an internal two-patch method. This technique is simple and reliable, and it appeared favorable in an elderly patient group. Six of 7 patients were treated with good results.     

Phytoplankton-mediated redox cycle of iron in the epilimnion of Lake Kinneret

The biological-mediated redox cycle of Fe was studied in the epilimnion of Lake Kinneret (Sea of Galilee), a mesotrophic lake in Israel. Multi-annual lake water sampling and incubation experiments were carried out to study Fe(III) reduction by natural phytoplankton populations and their possible role in inhibiting Fe(II) oxidation. The reduction characteristics of the dinoflagellate Peridinium gatunense, the dominant lake alga, were further examined in the laboratory. The steady-state concentration of Fe(II) calculated from the assessed reduction and oxidation rates was compared with Fe(II) measured in the lake in order to evaluate the significance of these processes to the lake Fe redox cycle. Nanomolar concentrations of Fe(II) were measured in the oxygenated, high pH, upper water layer of the lake throughout the year. Reduction rates of Fe by natural phytoplankton assemblages ranged between 0.1 and 10 nM/h. The highest reduction rates, determined in dinoflagellate-dominated lake waters, coincided with the highest concentrations of Fe(II) measured simultaneously in the lake. Iron(II) oxidation rates calculated from the measured lake Fe(II) and the obtained reduction rates were significantly slower than published abiotic Fe(II) oxidation rates. Indeed, Fe(II) oxidation rates measured in algal-enriched lake water were 30-fold slowerthan Fe(II) oxidation rates in natural water, demonstrating the potential for Fe(II) stabilization by the lake phytoplankton.     

Influence of MgO content as an additive on the performance of Ni/MgOSiO2 catalysts for the steam reforming of glycerol

Ni catalysts supported on MgOSiO₂ were assessed in the steam reforming reaction of glycerol for the study of the H₂ production and carbon deposition with different MgO contents as additives. The catalysts were prepared with commercial SiO₂ by the aqueous impregnation method and characterized by energy dispersive X-ray spectroscopy, specific surface area, X-ray diffraction, thermogravimetric analysis, X-ray diffraction in situ with O₂, temperature programmed reduction with H₂, X-ray diffraction in situ with H₂, temperature programmed desorption with H₂ and scanning electron microscopy. The glycerol steam reforming reaction took place at 600 °C for 5 h, with a water/glycerol molar ratio of 12/1 at 5 mLh^?1. N₂ was used as the carrier gas. The characterization of the samples showed the interaction of Ni with the support increases with the MgO addition, due to the formation of a NiMg silicate hydrate and MgNiO₂ solid solution; as a result, both metallic area and dispersion also increased. Catalytic results showed similar gaseous products yields (H₂, CH₄, CO and CO₂) for mixed-matrix catalysts, however, a lower carbon deposition on 10 wt%Ni catalyst supported on 30 wt%MgOSiO₂ was observed.     

Hydrogen production by steam reforming of ethanol over Ni-based catalysts promoted with noble metals

The catalytic activity of Ni/La₂O₃-Al₂O₃ catalysts modified with noble metals (Pt and Pd) was investigated in the steam reforming of ethanol. The catalysts were characterized by ICP, S_BET, X-ray diffraction, temperature-programmed reduction, UV–vis diffuse reflectance spectroscopy and X-ray absorption fine structure (XANES). The results showed that the formation of inactive nickel aluminate was prevented by the presence of La₂O₃ dispersed on the alumina. The promoting effect of noble metals included a marked decrease in the reduction temperatures of NiO species interacting with the support, due to the hydrogen spillover effect, facilitating greatly the reduction of the promoted catalysts. It was seen that the addition of noble metal stabilized the Ni sites in the reduced state throughout the reaction, increasing ethanol conversion and decreasing coke formation, irrespective of the nature or loading of the noble metal.     

Injectable Cardiac Cell Microdroplets for Tissue Regeneration

One of the strategies for heart regeneration includes cell delivery to the defected heart. However, most of the injected cells do not form quick cell–cell or cell–matrix interactions, therefore, their ability to engraft at the desired site and improve heart function is poor. Here, the use of a microfluidic system is reported for generating personalized hydrogel‐based cellular microdroplets for cardiac cell delivery. To evaluate the system's limitations, a mathematical model of oxygen diffusion and consumption within the droplet is developed. Following, the microfluidic system's parameters are optimized and cardiac cells from neonatal rats or induced pluripotent stem cells are encapsulated. The morphology and cardiac specific markers are assessed and cell function within the droplets is analyzed. Finally, the cellular droplets are injected to mouse gastrocnemius muscle to validate cell retention, survival, and maturation within the host tissue. These results demonstrate the potential of this approach to generate personalized cellular microtissues, which can be injected to distinct regions in the body for treating damaged tissues.     

Reducing resource use and emissions by integrating technology and policy solutions

Clean Technologies and Environmental Policy -     

Ethanol Steam Reforming by Ni Catalysts for H2 Production: Evaluation of Gd Effect in CeO2 Support

Catalysis Letters - Ni-based catalysts supported on CeO2 doped with Gd were prepared in this work to investigate the role of gadolinium on ethanol conversion, H2 selectivity, and carbon formation...     

Multi-enzyme production by pure and mixed cultures of Saccharomyces and non-Saccharomyces yeasts during wine fermentation

Saccharomyces and non-Saccharomyces yeasts release enzymes that are able to transform neutral compounds of grape berries into active aromatic compounds, a process that enhances the sensory attributes of wines. So far, there exists only little information about enzymatic activity in mixed cultures of Saccharomyces and non-Saccharomyces during grape must fermentations. The aim of the present work was to determine the ability of yeasts to produce extracellular enzymes of enological relevance (β-glucosidases, pectinases, proteases, amylases or xylanases) in pure and mixed Saccharomyces/non-Saccharomyces cultures during fermentation. Pure and mixed cultures of Saccharomyces cerevisiae BSc562, Hanseniaspora vinae BHv438 and Torulaspora delbrueckii BTd259 were assayed: 1% S. cerevisiae/99% H. vinae, 10% S. cerevisiae/90% H. vinae, 1% S. cerevisiae/99% T. delbrueckii and 10% S. cerevisiae/90% T. delbrueckii. Microvinifications were carried out with fresh must without pressing from Vitis vinifera L. c.v. Pedro Jiménez, an autochthonous variety from Argentina. Non-Saccharomyces species survived during 15-18days (BTd259) or until the end of the fermentation (BHv438) and influenced enzymatic profiles of mixed cultures. The results suggest that high concentrations of sugars did not affect enzymatic activity. β-Glucosidase and pectinase activities seemed to be adversely affected by an increase in ethanol: activity diminished with increasing fermentation time. Throughout the fermentation, Saccharomyces and non-Saccharomyces isolates assayed produced a broad range of enzymes of enological interest that catalyze hydrolysis of polymers present in grape juice. Vinifications carried out by a pure or mixed culture of BTd259 (99% of T. delbrueckii) showed the highest production of all enzymes assayed except for β-glucosidase. In mixed cultures, S. cerevisiae outgrew H. vinae, and T. delbrueckii was only detected until halfway the fermentation process. Nevertheless, their secreted enzymes could be detected throughout the fermentation process. Our results may contribute to a better understanding of the microbial interactions and the influence of some enzymes on vinification environments.     

Modelica-based modelling and simulation of dry-expansion shell-and-tube evaporators working with alternative refrigerant mixtures

A new methodology of intermediate complexity level is developed to model the dry-expansion shell and U-tube evaporators. The model has a reasonable level of accuracy and uses fundamental physical principles in a distributed parameters approach capable of detecting the complex circuit of the shell-side flow. This level of details is necessary to simulate accurately the zeotropic refrigerant mixtures evaporation. Using Modelica language gives a heat exchanger model with a generic flow arrangement. The model is experimentally validated using a standard shell-and-tube evaporator working with HFC-134a. Three distinct working fluids, pure HFC-134a, R-407C, and a specially selected glide matching refrigerant mixture are simulated in the same heat source duty with different shell-and-tube configurations. Three different gas superheat values are also taken into account. The total amount of irreversibility is considered by calculating the total exergy losses. It is concluded that the effect of the temperature profile of any refrigerant mixture can be substantial on the relative performance of a particular heat exchanger configuration compared to counter-flow configuration.