Pt-Ru-TiO2 photoelectrocatalysts for methanol oxidation

Novel photoelectrocatalysts composed of PtRuTiO₂/C are prepared by the polymeric precursor method and are characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy and cyclic voltammetry. The onset potential for methanol oxidation is similar (0.3 V vs. RHE) for all of the photoelectrocatalyst layers investigated, although the peak current density is dependent on the layer composition. Irradiation of UV light on the photoelectrocatalyst surfaces enhances the chronoamperometric responses up to 18%, which clearly demonstrates a synergistic effect between the photo- and electrocatalysts. The comparison between all the layers prepared indicates that there is an appropriate ratio of metallic nanoparticles and TiO₂ to obtain the best performance of these photoelectroactive layers. These results demonstrate that methanol oxidation is achieved by electro- and photocatalysis using a simple and affordable method. This procedure can be conveniently exploited to enhance the response of direct methanol fuel cell electrodes.     

Effects of spontaneous and inoculated fermentation on the volatile profile of lychee (Litchi chinensis Sonn) fermented beverages

The aim of this study was to evaluate the contribution of yeast to the volatile profile of beverages obtained by the fermentation of lychee must through inoculated (Saccharomyces cerevisiae strains UFLA CA116 , UFLA CA1183 and UFLA CA1174 ) and spontaneous fermentation. Higher alcohols and esters were the primary volatiles detected by SPME/GC–MS. A Principal Component Analysis indicated similarities between UFLA CA116 and UFLA CA1183 and between UFLA CA1174 and spontaneous fermentation. Changing the yeast strain used in the fermentation process has the potential to modulate the volatile profile of fermented beverages. The beverage produced by the inoculation of yeast CA1183 showed the most complex aroma profile compared to the other beverages.     

District heating and cooling for business buildings in Madrid

Energy needs for heating and cooling in Spain are of paramount interest in the context of the European roadmap to a decarbonized environment; because of that, it is highly desirable that more examples of district heating and cooling networks are developed. The present work evaluates the implementation of one of them into the climatic environment of Madrid. It consists on a complex of business office buildings with a total useful surface of 50,000 m², linked with heating and cooling rings of 1 km of loop length. Basic energy needs of buildings lead to the following design values: 1.7 MW of electricity, 1.3 MW of heating and 2 MW of cooling. They will be supplied by the trigeneration plant here proposed, which relies on an internal combustion engine.The high demand of cooling for air conditioning makes the dimensioning of the engine critical because of the large differences between the heat demand for summer and the one for winter. If the total amount of the cooling demand is covered with an absorption chiller, the heat demand during the summer reaches about 5 MW. In consequence, a critical decision has to be taken relative to the way the cooling demand is attended: with an absorption chiller (single or double effect) or with a conventional chiller powered by electricity. Applying the criteria developed in the present work, which are focused on maximum primary energy reduction, the fraction of the cooling demand to be met with each technology is determined as a function of the engine nominal power, on the grounds of the instantaneous demand.The high cooling demand during the summer season suggests the inclusion of a thermal solar collector field, to be used for complementing the waste heat rejection from the engine to drive the absorption chiller. During the winter, the heat provided by the solar field could be applied in attending a fraction of the heating demand. Thus a hybrid Trigeneration Plant is introduced. This way, over sizing of the engine can be avoided, as the electric demand is small.The analysis is based on the solution of energy and mass balance equations for a trigeneration plant. Monthly demands and environmental conditions (ambient temperature and solar irradiance) are introduced as input data into the model. Monthly and annual primary energy consumption and CO₂ emission reductions are obtained as outputs. Economical data, such as fuel and operating costs, electricity prices, tariffs and subsidies are considered in order to optimize the size of the plant in terms of its payback period.     

Inactivation of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella in cranberry, lemon, and lime juice concentrates

The production of thermally concentrated fruit juices uses temperatures high enough to achieve at least a 5-log reduction of pathogenic bacteria that can occur in raw juice. However, the transportation and storage of concentrates at low temperatures prior to final packaging is a common practice in the juice industry and introduces a potential risk for postconcentration contamination with pathogenic bacteria. The present study was undertaken to evaluate the likelihood of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella surviving in cranberry, lemon, and lime juice concentrates at or above temperatures commonly used for transportation or storage of these concentrates. This study demonstrates that cranberry, lemon, and lime juice concentrates possess intrinsic antimicrobial properties that will eliminate these bacterial pathogens in the event of postconcentration recontamination. Bacterial inactivation was demonstrated under all conditions; at least 5-log Salmonella inactivation was consistently demonstrated at -23 degrees C (-10 degrees F), at least 5-log E. coli O157:H7 inactivation was consistently demonstrated at -11 degrees C (12 degrees F), and at least 5-log L. monocytogenes inactivation was consistently demonstrated at 0 degrees C (32 degrees F).     

Replacement of Diesel Generator Sets in Isolated Communities with More Efficient Biomass Combustion Process

Electrical power supply to communities isolated from urban areas is typically complex and expensive. Their geographical situation and the lack of infrastructure and qualified workforce impede the provision of electricity. Many are the sources of energy available, but few are appropriate or sustainable. Combustion of diesel fuel is a good technical solution; however, it is neither economic nor environmentally tenable. This paper presents the advantages of using biomass as an energy source, along with its potential increase in efficiency when steam is generated in specific circumstances of temperature and pressure.     

Overview of hydrogen production technologies from biogas and the applications in fuel cells

Traditionally, H₂ is a large-scale production by the reforming process of light hydrocarbons, mainly natural gas, used by the chemical industry. However, the reforming technologies currently used encounter numerous technical/scientific challenges, which depend on the quality of raw materials, the conversion efficiency and security needs for the integration of H₂ production, purification and use, among others. Biogas is a high-potential versatile raw material for reforming processes, which can be used as an alternative CH₄ source. The production of H₂ from renewable sources, such as biogas, helps to largely reduce greenhouse gas emissions. Within this context, the integration of biogas reforming processes and the activation of fuel cell using H₂ represent an important route for generating clean energy, with added high-energy efficiency. This work expounds a literature review of the biogas reforming technologies, emphasizing the types of fuel cells available, the advantages offered by each route and the main problems faced.     

Intra- and interspecific mineral composition variability of commercial instant coffees and coffee substitutes: Contribution to mineral intake

The present paper reports the amount and estimated daily mineral intake of nine elements (Ca, Mg, K, Na, P, Fe, Mn, Cr and Ni) in commercial instant coffees and coffee substitutes (n = 49). Elements were quantified by high-resolution continuum source flame (HR-CS-FAAS) and graphite furnace (HR-CS-GFAAS) atomic absorption spectrometry, while phosphorous was evaluated by a standard vanadomolybdophosphoric acid colorimetric method.Instant coffees and coffee substitutes are rich in K, Mg and P (>100 mg/100 g dw), contain Na, Ca and Fe in moderate amounts (>1 mg/100 g), and trace levels of Cr and Ni. Among the samples analysed, plain instant coffees are richer in minerals (p < 0.001), except for Na and Cr. Blends of coffee substitutes (barley, malt, chicory and rye) with coffee (20–66%) present intermediate amounts, while lower quantities are found in substitutes without coffee, particularly in barley.From a nutritional point of view the results indicate that the mean ingestion of two instant beverages per day (total of 4 g instant powder), either with or without coffee, cannot be regarded as important sources of minerals to the human diet, although providing a supplementation of some minerals, particularly Mg and Mn in instant coffees. Additionally, and for authentication purposes, the correlations observed between some elements and the coffee percentage in the blends, with particular significance for Mg amounts, provides a potential tool for the estimation of coffee in substitute blends.     

Characterization of red wines from South America based on sensory properties and antioxidant activity

BACKGROUND: It is widely accepted that red wines constitute one of the most important sources of dietary polyphenolic antioxidants. However, it is still not known how some variables such as variety, vintage, country of origin, and retail price are associated with the antioxidant activity and sensory profile of South American red wines. In this regard, 80 samples produced in Brazil, Chile and Argentina were assessed in relation to their sensory properties, color and in vitro antioxidant activity, and results were subjected to multivariate statistical techniques. RESULTS: Samples were grouped in clusters, characterized by high, intermediate and low in vitro antioxidant activity, sensory properties and prices. It was possible to observe that wines with high antioxidant activity were associated to high retail prices and overall perception of sensory quality. CONCLUSION: South American wines produced from Vitis vinifera such as Syrah, Malbec and Cabernet Sauvignon had higher in vitro antioxidant activity and also higher sensory quality than wines produced from Vitis labrusca. This result was independent of vintage (2002‐2010), corroborating the idea that the same grape varietal, even when produced in different years, displays similar sensory characteristics and antioxidant activity. Copyright © 2011 Society of Chemical Industry     

Influence of slaughter season and sex on fatty acid composition, cholesterol and α-tocopherol contents on different muscles of Barrosã-PDO veal

The influence of slaughter season and sex on intramuscular total lipids (ITL) neutral lipid (NL) and phospholipid (PL) compositions, cholesterol and α-tocopherol contents were evaluated in Biceps femoris (Bf), Longissimus dorsi (Ld) and Supraspinatus (Ss) muscles from 92 Barrosã-PDO (Protected Denomination of Origin) calves. ITL content in Bf muscle was affected by slaughter season and sex whereas NL content was only affected by slaughter season. Neither sex nor slaughter season influenced cholesterol and α-tocopherol contents in the muscles under study. Concerning NL composition, sex was an important source of variation on the proportions of total SFA and MUFA in all muscles. Irrespective of the considered muscle, males had higher total SFA but lower total MUFA and MUFA/SFA contents than females. Slaughter season influenced C18:2 cis-9 trans-11 (CLA) content in Bf (P < 0.01) and in Ss muscles (P < 0.05) with calves slaughtered in autumn showing higher values than their counterparts. Total MUFA, n-3 PUFA and n-6/n-3 ratio contents in Ld muscle were also affected by slaughter season. Regarding PL composition, slaughter season × sex interaction affected total SFA, PUFA/SFA and n-6 PUFA contents in Bf and Ss muscles. In addition, this interaction influenced total MUFA (P < 0.05) in Bf muscle and total PUFA (P < 0.01) in Ss muscle. CLA content in PL from Ld was influenced by sex (P < 0.05) and by slaughter season (P < 0.01), with females slaughtered in autumn presenting the highest content. These results clearly indicate that sex and slaughter season are important factors that influence the fatty acid composition of Barrosã-PDO veal.     

Evaluation of the combined solar TiO2/photo-Fenton process using multivariate analysis.

The effect of combining the photocatalytic processes using TiO2 and the photo-Fenton reaction with Fe3+ or ferrioxalate as a source of Fe2+ was investigated in the degradation of 4-chlorophenol (4CP) and dichloroacetic acid (DCA) using solar irradiation. Multivariate analysis was used to evaluate the role of three variables: iron, H2O2 and TiO2 concentrations. The results show that TiO2 plays a minor role when compared to iron and H2O2 in the solar degradation of 4CP and DCA in the studied conditions. However, its presence can improve TOC removal when H2O2 is totally consumed. Iron and peroxide play major roles, especially when Fe(NO3)3 is used in the degradation of 4CP. No significant synergistic effect was observed by the addition of TiO2 in this process. On the other hand, synergistic effects were observed between FeOx and TiO2 and between H2O2 and TiO2 in the degradation of DCA.