Mixture design applied for the development of films based on starch,polyvinyl alcohol,and glycerol

Starch and polyvinyl alcohol (PVA) are biodegradable materials with potentiality to replace the conventional polymers in some applications. The aim of this work was to produce biodegradable films of PVA, cassava starch, and glycerol by thermoplastic extrusion using a mixture design to evaluate the effects of each component in the blend properties. Six formulations were prepared using a twin‐screw extruder coupled with a calender. All the materials were visually homogeneous and presented good processability. Mechanical properties were dependent on both the relative humidity conditioning and the formulation; higher relative humidities detracted the mechanical properties, which was associated to plasticizer effect of the water. Furthermore, the mechanical properties were better when higher concentrations of PVA were used, resulting in films with lower opacity, lower water vapor permeability, and higher thermal stability, according to TGA. Biodegradable materials based on starch, PVA, and glycerol have adequate mechanical and processing properties for commercial production. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42697.     

Antibacterial polymeric coating based on polypyrrole and polyethylene glycol on a new alloy TiAlZr

In order to enhance properties of the polymer composite films, composite coatings based on polypyrrole (PPy) and polyethylene glycol (PEG), using various percentages of PEG (0.5%, 2%, 4%), were electrodeposited on a new titanium alloy electrode as insulating material. The structure of the coatings was investigated via infrared (FTIR) analysis, and the surface features were studied using contact angle determination, atomic force microscopy (AFM) and scanning electronic microscopy (SEM). When testing the antibacterial properties of the coatings, the best effect was found for the coating with 2% PEG concentration, which has hydrophilic character and small roughness. Such results are in concordance with mechanism of biomaterial–bacteria interaction which involves as factors affecting bacterial adhesion and growth an initial physicochemical interaction stage, where roughness and wettabilitty are factors promoting bacterial adhesion and biofilm deposition.     

Extrusion Cooking of Cassava Starch for Ethanol Production

Response surface methodology was used to study the effect of extrusion variables on gelatinization and viscosity of cassava starch with the aim to reduce energy consumption in alcohol production. None of the variables significantly affected the degree of gelatinization and moisture content of starch was the only significant variable affecting cold viscosity. Torque was affected by all the variables moisture being the most important. Extrusion was an efficient pre-treatment for simultaneous saccharification and fermentation of cassava starch, resulting in 92.4% ethanol conversion. The best conditions for continuous process were: 100°C. 70 rpm, 4 mm die opening and 25-27% moisture. For discontinuous process, when the extruded starch would be dried and ground 200°C, 190 rpm, 4 mm die opening and 20% moisture is recommended.     

Implementing the Omega failure detector in the crash-recovery failure model

Unreliable failure detectors are mechanisms providing information about process failures, that allow to solve several problems in asynchronous systems, e.g., Consensus. A particular failure detector, Omega, provides an eventual leader election functionality. This paper addresses the implementation of Omega in the crash-recovery failure model. We first propose an algorithm assuming that processes are reachable from the correct process that crashes and recovers a minimum number of times. Then, we propose two algorithms which assume only that processes are reachable from some correct process. Besides this, one of the algorithms requires the membership to be known a priori, while the other two do not.     

A new algorithm to compute conjectured supply function equilibrium in electricity markets

Several types of market equilibria approaches, such as Cournot, Conjectural Variation (CVE), Supply Function (SFE) or Conjectured Supply Function (CSFE) have been used to model electricity markets for the medium and long term. Among them, CSFE has been proposed as a generalization of the classic Cournot. It computes the equilibrium considering the reaction of the competitors against changes in their strategy, combining several characteristics of both CVE and SFE. Unlike linear SFE approaches, strategies are linearized only at the equilibrium point, using their first-order Taylor approximation. But to solve CSFE, the slope or the intercept of the linear approximations must be given, which has been proved to be very restrictive.This paper proposes a new algorithm to compute CSFE. Unlike previous approaches, the main contribution is that the competitors’ strategies for each generator are initially unknown (both slope and intercept) and endogenously computed by this new iterative algorithm.To show the applicability of the proposed approach, it has been applied to several case examples where its qualitative behavior has been analyzed in detail.     

Catalytic performance of silica-aluminas synthesised with the help of chitosan biopolymer

Mesoporous amorphous silica-aluminas were synthesised with standard aluminium and silicon sources by means of the formation of inorganic–organic composites with the addition of chitosan biopolymer, and compared to analogous catalysts synthesised conventionally. Some catalysts were subjected to hydrothermal treatment. The resulting specific surface areas were from 480 to 573 m²/g in the untreated samples and 300–430 m²/g in the hydrotreated catalysts, average pore sizes ranging from 32 to 100 Å with sharp, unimodal distributions. The chitosan materials showed higher specific surface areas and larger pore sizes than those of their non-chitosan counterparts. The most important differences in the acidic properties were in the relationships between tetrahedral and octahedral aluminium atoms, the chitosan materials having higher relative amounts of tetrahedral aluminium than the conventional silica-aluminas. Evidences of stabilization in the physical and chemical properties were observed in the chitosan-containing catalysts. The catalytic performance was evaluated with the conversion of tri-isopropylbenzene at 400 °C, to assess activity and accessibility, and cyclohexene at 300 °C, to assess hydrogen transfer properties. The highest activity and accessibility was observed in the hydrotreated, chitosan-containing catalyst, while hydrogen transfer capabilities were similar to those of medium unit cell sizes, equilibrium commercial FCC catalysts.     

Dehydrogenase Enzymes Associated to Glycolysis in Beef Carcasses Stored at 0 °C

After the death of an animal, cell metabolism is controlled locally. The post-mortem oxygen depletion increases the glycolytic activity and lactate production. However, many mechanisms of post-mortem metabolic regulation have not been fully investigated in beef carcasses. In this work, we studied the post-mortem glycolytic behavior (including lactate dehydrogenase) and three dehydrogenase associated to glycolysis (glycerophosphate dehydrogenase, glucose 6-phosphate dehydrogenase, and glycerol dehydrogenase) by using cytochemistry techniques in three fast-twitch muscles (M. longissimus dorsi, M. semimembranosus, and M. cutaneus trunci) of carcasses stored at 0 °C. Our results indicate that glycolysis depends on the type of muscle. The post-mortem glycolytic flux and lactate dehydrogenase activity of M. cutaneus trunci was the lowest of the three muscles studied. Of the other dehydrogenases analyzed, only glycerophosphate and glycerol dehydrogenase showed clear cytochemical reaction. Glucose 6-phosphate dehydrogenase was not used by muscles very much. The glycerophosphate dehydrogenase was the strongest enzymatic activity correlated to the post-mortem glycolytic flux. In addition, a relationship between glycerophosphate dehydrogenase and glycerol dehydrogenase was detected by using a multiple regression model. This phenomenon was studied by using bioinformatics tools, suggesting that glycerophosphate dehydrogenase could oxidize the glycerol in bovine fast-twitch muscles.     

A non-destructive digital imaging method to predict immobilized yeast-biomass

In food fermentation, many types of immobilization systems are used, such as hydrogel entrapment, where alginate is the main biopolymer. One of the important problems in industrial processes is the quantifications of biomass, since the traditional system of direct cell counting cannot be used. In this study, a simple digital imaging method to determine the biomass of yeasts immobilized into alginate capsules was developed. Important evidence of the yeasts growing inside the alginate was the change in the surface color of the capsule. Digital images were taken with different biomass concentration, and the RGB-analysis showed significant differences in the blue field. The histogram of the blue channel was used to develop a PLS multivariate calibration to predict biomass concentration. The method was validated in primary beer fermentation with good efficiency.     

The role of psychology and social influences in energy efficiency adoption

Current energy efficiency policy and incentive programs tend to target economic motivations, which may misalign with other potentially important motivations arising from situational factors, individual differences, and social context. Thus, in this research, we review areas of work that have focused on psychological and social influences to energy efficiency adoption in commercial buildings. We then conduct an empirical scoping study interviewing 10 commercial building owners/managers (decision makers) and 10 experts/consultants (decision influencers) regarding perceived motives and barriers to energy efficient investments, decision-maker attributes, and the social context of the decision. Potential factors that emerge from the interviews, which are not yet extensively discussed in the energy efficiency literature, include owners/managers’ resistance to change and the influence of investment funding origins on the decision. Our results also suggest potential heterogeneity in energy efficiency decision-making philosophies between the two groups. Interviewed owners/managers prioritize corporate social responsibility (CSR) and prefer internal consulting (e.g., building engineers). Conversely, experts/consultants do not emphasize CSR and are more concerned with external policies. These findings suggest that accounting for the decision maker and the social context in which decisions are made could enhance the design of commercial sector energy efficiency programs.