Characterization of a miniaturized liquid bridge for nL sample infusion: a comparative study of sample flush-out behavior using flow simulations and direct ESI-MS analysis

In this work we shed light on the microfluidics of a miniaturized liquid bridge that forms the central part of a so-called “capillary gap sampler,” a novel device for rapid and seamless injection of nanoliter sample volumes into an electrospray ionization mass spectrometer (ESI-MS). Parameters relevant for sample flush-out at the liquid bridge and in the spray capillary were identified by systematic variation of the capillary dimensions, the linear buffer flow rate (2.1–34 mm/s) and molecular weight of the analytes (0.5–30 kDa). We found that a reduction in capillary wall thickness by a factor of 1.6 significantly influences analyte peak shapes, leads to an inversion of the relationship between peak width and analyte molecular weight, and allows a fivefold decrease in peak width for large molecules down to 5 s. The results could be verified and explained by simulations, in which the presence of diffusion-controlled “dead zones” at the liquid bridge and dispersion in the spray tip that depend on analyte molecular weight were identified as key factors relevant for the sample flush-out process. The merging of simulations and experimental data gives useful hints toward the re-design of a spray tip as built-in ESI-MS interface for an optimized gap sampler performance.     

Metaheuristic optimization frameworks: a survey and benchmarking

This paper performs an unprecedented comparative study of Metaheuristic optimization frameworks. As criteria for comparison a set of 271 features grouped in 30 characteristics and 6 areas has been selected. These features include the different metaheuristic techniques covered, mechanisms for solution encoding, constraint handling, neighborhood specification, hybridization, parallel and distributed computation, software engineering best practices, documentation and user interface, etc. A metric has been defined for each feature so that the scores obtained by a framework are averaged within each group of features, leading to a final average score for each framework. Out of 33 frameworks ten have been selected from the literature using well-defined filtering criteria, and the results of the comparison are analyzed with the aim of identifying improvement areas and gaps in specific frameworks and the whole set. Generally speaking, a significant lack of support has been found for hyper-heuristics, and parallel and distributed computing capabilities. It is also desirable to have a wider implementation of some Software Engineering best practices. Finally, a wider support for some metaheuristics and hybridization capabilities is needed.     

Optimization and CFD modeling of an improved rustic oven for producing bricks

Clean Technologies and Environmental Policy - This paper presents an optimization formulation and a computational fluid dynamic study for a new proposal of a rustic oven that uses natural gas...     

Enzymatic modifications of pea protein and its application in protein-cassava and corn starch gels

The interactions between starch and proteins during processing influence pasting and rheological properties of starch and produce modifications on starch gel structure. Enzymatic modifications have been proposed for overcoming the limitations of using proteins as food ingredients. This work aimed to study the impact of native and enzymatically modified pea proteins on the properties of protein-starch (from cassava or corn) gels. Pea protein isolate (PPI) was incubated with endopeptidase (AL) or microbial transglutaminase (TG). Pasting profile, rheological behaviour and water retention capacity of protein-starch gels were analyzed. Protein (native and enzymatically modified) incorporation increased the viscosity of both corn and cassava starches during gel preparation. However, the hydrolyzed protein reduced drastically the increment of viscosity of protein-starch gels. The addition of PPI led to corn starch network that shifted from an elastic-like nature to a more viscous-like, whereas the opposite effect was observed in cassava gel network. TG- and AL-treated proteins led to a decrease of both G′ and G″ moduli of protein-starch gels, and AL-treated proteins showed the highest decrease on these parameters. Hydrolyzed proteins also favoured the syneresis of the protein-corn starch gel, whereas crosslinked proteins tended to reduce it. Enzymatic modifications of pea proteins affected significantly pasting and rheological properties of protein-starch gels.     

Design and optimization of thermo-electrochemical cells

Thermo-electrochemical cells (or thermocells) convert thermal energy to electricity in continuous operation based on a balance of ion conduction and redox reactions at hot and cold electrodes. In this study, the fundamental governing equations for mass and heat transfer, fluid dynamics, and electrokinetics in thermocells are presented and solved numerically using COMSOL. A parametric study is performed to explore the limitations and optimal cell dimensions for maximum energy conversion efficiency in thermocells. Series-stacking designs are demonstrated to have the potential to increase conversion efficiency by 100 % compared to a single cell configuration. Natural convection is shown to significantly increase the conversion efficiency of thermocells with conventional aqueous electrolyte (0.4 M potassium ferri/ferrocyanide), by compressing the diffusive boundary layers. A flow cell thermocell design is also considered. Results reveal that the ohmic resistance of the electrolyte limits the energy conversion efficiency of this design.     

Determining the responsibility of manufacturing sectors regarding electricity consumption. The Spanish case

The aim of this paper is to develop a methodology based on the input-output approach which allows us to identify the structural and technological responsibility of manufacturing sectors in electricity consumption. Sectors with a high structural responsibility are those whose products are strongly demanded by other sectors and this leads to a high electricity consumption/production. Sectors with a high technological responsibility are those whose technologies use inputs which directly or indirectly require much electricity independently of the composition of final demand in the economy. This methodology is applied to the manufacturing sectors in Spain. It is found out that the chemical sector and industries manufacturing metal products have a large structural responsibility, but their technological responsibility is low. In contrast, the mineral (non-metallic) sectors form a cluster of industries with a high technological responsibility.     

Intelligent micellar polymeric nanocarriers for therapeutics and diagnosis

Polymeric micelles can be designed and synthesized to bear polymeric blocks with different hydrophilicities; this triggers their self‐assembly into micellar aggregates similar to those generated with traditional surfactants. The basic structure consists of a hydrophobic core, capable of containing guest substances, and a hydrophilic shell, which stabilizes the payload and protects it from external degradation or prevents its quick elimination from the body. The accumulation of block copolymer micelles (BCMs) in a target cell or tissue can be accomplished by two main mechanisms, passive and active targeting; this allows the payload release at the site of action when desired. Hence, in this general overview, we pay special attention to newly developed single‐stimulus‐ and multi‐stimuli‐responsive delivery systems capable of disassembling and reassembling (in some cases) as a response to changes in their physicochemical properties. Also, special interest is also devoted to multifunctional BCMs incorporating multiple therapeutic agents and/or multiple imaging contrast agents, which can be considered the new generation (third generation) of drug‐delivery systems, that is, nanotheranostic platforms. Finally, a summary of BCM‐based drug‐delivery systems currently under clinical trials is given. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42650.     

Short-term dynamics of soil chemical parameters after application of alperujo in high-density drip-irrigated olive groves in Argentina

Two-phase olive oil mills generate a semi-solid waste made of olive pulp, olive stone, and vegetation water commonly called ‘alperujo’. Lack of disposal alternatives drives many Argentinean olive oil producers to apply it directly as soil amendment to the olive orchards. Even though this practice has been widely evaluated in Mediterranean countries, there is little agreement on the environmental impact that it may produce. In this work a surface layer of alperujo was applied to a high-density, drip-irrigated olive orchard, and different parameters were monitored. This report summarises the dynamics of soil chemical properties during the first 200 days after application. The results obtained showed that soil amended with alperujo increased total organic matter (OM), nitrogen (N) and available potassium (K), without affecting soil electrical conductivity (EC), pH and C/N ratio. The results suggest that surface application of alperujo may represent an attractive alternative to disposal under conservationist management. Further research evaluating long term effects on chemical and biological indicators must be performed to ensure the sustainability of alperujo as soil amendment.     

Montmorillonite as support for peroxide in the melt grafting of maleic anhydride onto polypropylene

Grafting of maleic anhydride onto polypropylene was performed in a Haake torque rheometer, in the presence of organically modified montmorillonite, MMT (used as support for the peroxide), according to a 2³ factorial design, where the maleic anhydride concentration (C_MA), peroxide concentration (C_per) and reaction time (t_r) were varied. For comparison, the reaction in the absence of MMT was also conducted. Polypropylene degradation was assessed by parallel plate rheometry and size exclusion chromatography (SEC) and percentage of reacted maleic anhydride (%MA_g) was obtained by titration and FTIR spectroscopy. The results showed differences in both systems, conventional and in the presence of MMT. The structure of polypropylene grafted with maleic anhydride, PP‐g‐MA, indicates longer branches are formed in the presence of MMT compared to in its absence, demonstrated by FTIR analysis. As in conventional reaction systems, an increase in C_per caused an increase in %MA_g and a reduction in molar mass. The variable C_MA showed to be not significant in the grafting reaction in the presence of MMT, even at high DCP levels, at a 5% significance level. On the other hand, increase in C_MA resulted in significant increase in viscosity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44134.