Ethylene production,respiration and gas exchange modelling in modified atmosphere packaging for banana fruits

A mathematical model was developed from experimental measurements to describe the evolution of the O₂, CO₂ and ethylene in a modified atmosphere packaging system for Cavendish bananas. The respiration and ethylene production in the fruits were experimentally obtained from a closed system method and then represented by Michaelis–Menten equations of enzyme kinetics. The gas transfer through the packaging was described by a Fick's diffusion equation, and the temperature dependence was represented based on the Arrhenius law. The model was validated by packaging the fruit in perforated bags of polypropylene and low density polyethylene at 12 °C for a period of 8 days. With the developed model it was possible to satisfactorily describe the experimental evolution of the gas content in the headspace of the packages, obtaining coefficients of determination (R²) of 0.93 for the O₂ levels, 0.90–0.91 for the CO₂ levels, and 0.89–0.93 for the ethylene levels.     

Virulence-resistance plasmids (pUO-StVR2-like) in meat isolates of Salmonella enterica serovar Typhimurium

During a screening of Salmonella enterica in foods of animal origin four isolates of serovar Typhimurium carrying hybrid virulence-resistance plasmids were detected. Three of them, one from pork and two from chicken meat, contained pUO-StVR2, a derivative of the pSLT virulence plasmid with the bla_OXA-1, catA1, aadA1, sulI and tet(B) genes, which confer resistance to ampicillin, chloramphenicol, streptomycin-spectinomycin, sulfonamides and tetracycline, respectively. The fourth isolate, from pork, harbored a pUO-StVR2 variant (termed ν8) with an additional dfrA10 gene responsible for resistance to trimethoprim. This gene is part of the orf513-dfrA10-qacEΔ1-sul1 element characteristically found in complex class 1 integrons. Pulsed-field gel electrophoresis identified two XbaI-BlnI combined profiles: X2-B2 generated from the three pUO-StVR2 isolates, and X12-B17 shown by the pUO-StVR2-ν8 isolate. The same profiles have also been found in clinical and ill pig isolates, supporting chicken and pork meat as vehicles for transmission of Typhimurium carrying pUO-StVR2-like plasmids.     

Overview of underground coal gasification operations at Chinchilla,Australia

Underground coal gasification (UCG) is a process which converts deep, un-mineable or difficult to mine coal resources into syngas which can then be converted into valuable end products such as electric power, liquid fuels, synthetic natural gas and chemicals. This paper provides a summary of the UCG operations conducted at the Chinchilla Demonstration Facility in Australia, focusing on gasifiers constructed using directional drilling. A number of the experiences and key lessons learned from operating multiple underground gasifiers over several years at the facility are described. Implications for the implementation in commercial projects using UCG are also discussed. Finally, the potential of UCG as a method for producing syngas from deep coal is discussed and some of the challenges and opportunities are summarized.     

Implementing the European “Floods Directive”: the Case of the Po River Basin

The European “Floods Directive” 2007/60/EC (FD) asks Member States to develop flood risk maps on the bases of most appropriate and advanced tools, with particular attention on limiting required economic efforts. The question arises on how these tools should be selected so as to supply all the knowledge that is required to develop Flood Risk Management Plans (FRMPs). By analysing the implementation of the FD in the Po River Basin (Italy), the paper describes and compares two different approaches for flood risk assessment: the expert driven-qualitative approach vs. the quantitative approach based on damage models. The comparison shows, as expected, that quantitative approaches supply more useful knowledge for the development of FRMPs (and for flood risk management in general) with respect to qualitative approaches. However, they still present limits which prevent their adoption without critically consider the peculiarities of the investigated area in terms of available knowledge on hazard, exposure and vulnerability. Accordingly, considerations are supplied on how effectiveness of quantitative approaches can be maximized, towards flood risk management objectives.     

Particle–Fluid–Structure Interaction for Debris Flow Impact on Flexible Barriers

Flexible barriers are increasingly used for the protection from debris flow in mountainous terrain due to their low cost and environmental impact. However, the development of a numerical tool for the rational design of such structures is still a challenge. In this work, a hybrid computational framework is presented, using a total Lagrangian formulation of the finite element method to represent a flexible barrier. The actions exerted on the structure by a debris flow are obtained from simultaneous simulations of the flow of a fluid‐grain mixture, using two conveniently coupled solvers: the discrete element method governs the motion of the grains, while the free‐surface non‐Newtonian fluid phase is solved using the lattice Boltzmann method. Simulations on realistic geometries show the dependence of the momentum transfer on the barrier on the composition of the debris flow, challenging typical assumptions made during the design process today. In particular, we demonstrate that both grains and fluid contribute in a nonnegligible way to the momentum transfer. Moreover, we show how the flexibility of the barrier reduces its vulnerability to structural collapse, and how the stress is distributed on its fabric, highlighting potential weak points.     

Production of stable amorphous form by means of spray drying

Spray drying is a very useful method for manufacturing of amorphous solid materials. This is mainly due to the possibility of fast solvent evaporation that leads to a rapid transformation of solution to a solid state. Besides evaporation kinetics, there are various process parameters that influence physical and chemical characteristics of such obtained material. The possibility of obtaining a stable amorphous structure of the active pharmaceutical ingredient in a spray dryer was examined. A solution of the hydrochloride crystalline structure of the active pharmaceutical ingredient in a mixture of water and acetonitrile was dried at different temperatures and flowrates of nitrogen used for atomization, as well as the flowrates of the solution. The influence of the process conditions on the properties of the product was analyzed. The final dried products were characterized and identified with a variety of analytical and physical methods. The results showed that a stable amorphous structure of the high purity active pharmaceutical ingredient is obtained, and that the optimal conditions of the process are defined. The amorphous structure is stable at temperatures below 200°C when it is transformed into a new crystal structure. Conditions of high relative air humidity lead to partial transformation.     

In vitro digestibility of phenolic compounds from edible fruits: could it be explained by chemometrics?

The health benefits of phenolic compounds depend on the ingested amount, molecular diversity and gastrointestinal digestibility. The phenolic profile of eight fruits (blackberry, blueberry, strawberry, raspberry, mulberry, pomegranate, green and red globe grapes) was chemometrically associated with their in vitro digestibility (oral, gastric, intestinal). Extractable phenols, flavonoids and anthocyanins strongly correlated with each other (r ≥ 0.84), proanthocyanidins with anthocyanins (r = 0.62) and hydrolysable phenols with both extractable phenols (r = 0.45) and proanthocyanidins (r = ?0.54). Two principal components explained 93% of the variance [61% (free‐phenols), 32% (bounded‐phenols)], and four clusters were confirmed by hierarchical analysis, based in their phenolic richness (CLT 1‐4: low to high) and molecular diversity. In vitro digestibility of extractable phenols and flavonoids was blackberry (CLT‐4)> raspberry (CLT‐2)> red grape (CLT‐1) related to their phenolic richness (r ≥ 0.96; P < 0.001), but anthocyanins’ digestibility was pH‐dependent. Chemometrics is useful to predict the in vitro digestibility of phenolic compounds in the assayed fruits.     

Effect of different acid and lithium salt used in polyethylene glycol–titanium oxide based solvent-free electrolytes on electrochromic performance of WO3 thin films

Polymeric nanocomposites of polyethylene glycol (PEG) with titanium oxide compound, PEG–Ti, are solvent-free viscous materials obtained by sol–gel method in acidic medium. Lithium salt (LiX) has been added into PEG–Ti to form PEG–Ti–LiX polymeric electrolytes. Electrochromic devices based on tungsten oxide thin films and PEG–Ti–LiX electrolyte may show excellent optical contrast in the wavelength range from 300 to 2500 nm, however it depends on the type of lithium salt as well as the acid source used during the sol–gel process. With LiI, the color change speed of the devices is very fast, but they show a yellow color at bleaching state. The use of LiClO₄ makes the devices totally transparent in visible region, and the optical contrast is small. On the other hand, hydrochloric acid is good catalyst for hydrolysis of the titanium precursor during the sol–gel process, but it also originates the yellowish appearance of the devices. The substitution of HCl by acetic acid makes the devices more transparent in 250–500 nm, but the optical contrast as well as color change speed were deteriorated. Possible chemical reaction mechanisms during the formation of these polymeric electrolytes have been proposed to explain the relation between electrochromic performance of tungsten oxide and chemical composition of the electrolytes.