Antibacterial activity of cranberry juice concentrate on freshness and sensory quality of ready to eat (RTE) foods

Ready-to-eat (RTE) foods are not further treated before consumption in such a way that may significantly reduce the microbial load, therefore the risk of foodborne disease must be considered. In this regard, the use of natural antimicrobial compounds is an interesting method to be considered. On this topic, the antibacterial activity of cranberry juice concentrate (CJC) have been evaluated in vitro and in situ against 3 foodborne pathogenic bacteria. Results showed a high antimicrobial effect with a noticeable inhibition capacity against Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium. Acid sensitivity studies of bacteria indicated that at the same pH level (pH = 2.4) in presence of organic acid solution (citric and quinic acids), cranberry juice concentrate showed greater antibacterial effects than the acids due to their phenolic compounds. In situ studies showed 2.5, 1.8 and 5 log reduction of E. coli, L. monocytogenes and S. typhimurium, respectively in presence of cranberry juice concentrate, on pre-cut red peppers after 7 days of storage at 4 °C. A total inhibition of L. monocytogenes on fresh cranberry fruits in primary day of storage, was observed. Cranberries treated with CJC also showed a 3 log reduction of S. typhimurium after 4 days of storage at 4 °C. The results suggest that CJC can be an effective preservation, source of natural antibacterial, to protect the RTE foods from foodborne pathogens contamination without effecting on sensorial properties of treated samples and allow to maintain the freshness, sensory and the nutritional quality of RTE foods.     

High-yield production of N-doped graphitic platelets by aqueous exfoliation of pyrolyzed chitosan

Full exploitation of the properties of N-doped graphene and few-layers graphitic platelets will require a method for the mass production of this highly conductive material. Herein the preparation of few-layers graphitic platelet dispersions at concentrations up to 0.16 mg ml⁻¹ is reported. These suspensions are produced by dispersion and exfoliation of N-doped graphitic carbons obtained from the chitosan biopolymer. This high concentration derives from the morphology of pyrolyzed chitosan constituted by a graphitic carbonaceous residue with loose stacking of the graphene sheets that is prone to undergo easy exfoliation. The presence of few layers graphitic sheets was confirmed by Raman spectroscopy, transmission electron microscopy, electron diffraction and atomic force microscopy. Our method results in the formation of N-doped graphitic platelet suspensions with a yield of 40 wt.% of the initial graphitic carbon, which could potentially be improved to 90 wt.% by four consecutive sonication–centrifugation cycles of the same pyrolyzed chitosan residue. The absence of defects or oxides is confirmed by X-ray photoelectron, infrared and Raman spectroscopies. Solution processing of graphene and few-layers graphitic flakes opens up a range of potential large-area applications, from device and sensor fabrication to liquid-phase chemistry.     

The long-run price elasticity of residential demand for electricity: Results from a natural experiment

In one of two otherwise similar adjacent regions in a Canadian province, the price of electricity changed abruptly, substantially, and permanently. That natural experiment allows for a simple differences-in-differences calculation of the long-run price elasticity of residential demand for electricity. This analysis is of interest for two reasons. First, it is a rare circumstance when such a methodology can be used. Secondly, the magnitude of the elasticity estimate has substantial implications for utilities, regulators, and policymakers.     

Dependence of pressure on elastic,electronic and optical properties of CeO2 and ThO2: A first principles study

The phase transformation of CeO₂ and ThO₂ from fluorite to cotunnite-type structure under pressure is predicted within the density functional theory implemented with the GGA-PW91 method, the pressure induced structural phase transition occurs at 28.9 GPa for CeO₂ and 29.8 GPa for ThO₂. These values are in excellent agreement with the experimentally measured data. The elastic, electronic and optical properties at normal as well as for high-pressure phase have been calculated, particular attention is devoted to the cotunnite phase. Further, the dependence of the elastic constants, the bulk modulus B, the energy band gaps and the dielectric function on the applied pressure are presented.     

Computational evolutionary inverse lagrangian puff model

This article presents a model based on the principles of evolutionary computation and on the principles of dispersion of an Inverse lagrangian puff model of the type Backward gaussian puff tracking in order to determine the spatial behavior over time of the concentration for PM_2.5 and PM₁₀ in a study area.     

Effect of Cobalt Content on the Oxidation and Corrosion Behavior of Ni–Fe-Based Superalloy for Ultra-Supercritical Boiler Applications

The oxidation and corrosion behavior of three model alloys with different cobalt contents (6–20 wt%) were investigated in static air and a simulated coal ash/gas environment at 750 °C. The model alloys follow a parabolic law approximately during the oxidation in static air. High cobalt level improves the oxidation resistance, however, without noticeable improvement in coal ash/gas corrosion resistance. The sample with the highest cobalt content grows the thinnest oxide layer and the fewest internal oxidation products in the oxidation test. Cobalt in the model alloys promotes the establishment of a protective chromium oxide scale during the oxidation test, but did not show much difference in restraining the inward diffusion of sulfur by increasing its content. The oxidation and corrosion products formed on the sample surface consist mainly of a protective chromium oxide film. Internal aluminum oxide particles have been found especially along the grain boundaries of the base alloy.     

Upgrading the Arlberg tunnel to current safety standards

Austrian road tunnels within the Trans-European Road Network (TERN) must fulfil the requirements of the Directive 2004/54/EC (European Commission, 2004) not later than April 2019. This regulation has to be applied to all tunnels in the TERN with a length of more than 500 m, whether they are in operation, under construction or at design stage, and aims at ensuring a minimum level of safety for road users. One of the main features of this directive is the requirement for providing an egress possibility to a safe environment every 500 m throughout the whole tunnel.The Arlberg road tunnel has a length of some 15.5 km and is in operation for more than 35 years. It is a single tube tunnel operated with bi-directional traffic, but carries a quite low traffic volume. Hence, the construction of a second tube is not really cost effective. Currently the tunnel is equipped with a transversal ventilation system with remotely controlled smoke extraction dampers providing smoke extraction every 100 m. The maximum distance between egress possibilities to a save environment is some 1500 m. Due to the high costs of a construction of a second tube or a parallel running escape gallery, a novel solution was found. The existing fresh air duct will be used as safe escape way between the existing egress possibilities. This solution has big impacts on the ventilation system and on the requirements for thermal structure protection of the new egress ways, i.e. the fresh air duct. In order to overcome this problem, massive changes in the ventilation design have to be performed, accompanied by the installation of a high-pressure water-mist system for structure protection.     

A study on the tensile response and fracture in carbon nanotube-based composites using molecular mechanics

A study on the mechanical properties of polyethylene and carbon nanotube (CNT) based composites is presented using molecular mechanics simulations. The systems being investigated consist of amorphous as well as crystalline polyethylene (PE) composites with embedded single-walled CNTs. All the systems are subjected to quasi-static tensile loading, with the assumption that no cross-link chemical bonds exist between the CNT and polyethylene matrix in the case of nanocomposites. Based on the numerical simulations, we report Young’s moduli (C₃₃) of 212–215 GPa for crystalline PE, which closely match the experimental measurement. Furthermore, elastic stiffness of 3.19–3.69 GPa and tensile strength of 0.21–0.25 GPa are obtained for amorphous PE. The tensile responses are found to be highly isotropic. In the case of crystalline PE reinforced by long through CNTs, moderate improvements in the tensile strength and elastic stiffness are observed. However, the results differ from the predictions using the rule of mixtures. On the other hand, although significant increase in the overall tensile properties is observed when amorphous PE is reinforced by long through CNTs, the load transfer at the nanotube/polymer interface has negligible effect. Finally, degradations in both tensile strength and elastic stiffness are reported when amorphous PE is reinforced by embedded CNTs. The study presented indicates the importance of specific CNT and polymer configurations on the overall properties of the nanocomposite.     

Integration of Multiple Plasmonic and Co‐Catalyst Nanostructures on TiO2 Nanosheets for Visible‐Near‐Infrared Photocatalytic Hydrogen Evolution

Utilization of visible and near‐infrared light has always been the pursuit of photocatalysis research. In this article, an approach is developed to integrate dual plasmonic nanostructures with TiO₂ semiconductor nanosheets for photocatalytic hydrogen production in visible and near‐infrared spectral regions. Specifically, the Au nanocubes and nanocages used in this work can harvest visible and near‐infrared light, respectively, and generate and inject hot electrons into TiO₂. Meanwhile, Pd nanocubes that can trap the energetic electrons from TiO₂ and efficiently participate in the hydrogen evolution reaction are employed as co‐catalysts for improved catalytic activity. Enabled by this unique integration design, the hydrogen production rate achieved is dramatically higher than those of its counterpart structures. This work represents a step toward the rational design of semiconductor–metal hybrid structures for broad‐spectrum photocatalysis.     

Correlation between ultrafast transient photomodulation spectroscopy and organic photovoltaic solar cell efficiency based on RR-P3HT/PCBM blends

Ultrafast transient spectroscopy was applied to various films of regio-regular polythiophene (RR-P3HT, donor-D) and C₆₀ derivative (PCBM, acceptor-A) blends, in conjunction with organic photovoltaic (OPV) solar cell fabrication and evaluation based on the same blends, for investigating the existence of a correlation between the device efficiency and the transient photophysics characteristics. For our transient spectroscopy measurements we used the ps pump–probe transient photomodulation (PM) technique having a unique probe spectral range in the mid-IR (0.25–1.05 eV). We found that the transient PM spectra contain photoinduced absorption bands of excitons in the donor polymer, charge transfer excitons (CTE) at the D–A interfaces, and free polarons. We compared the relative density of photogenerated CTE in D–A blends having various D–A weight ratio with the photocurrent density of fabricated solar cells based on the same blends. We found that the dissociation of CTE into free charges correlates well with the optoelectronic measurements of the corresponding solar cell. The more efficient CTE dissociation occurs in films having the optimum D–A weight ratio (which is 1.2:1 for the P3HT/PCBM system) that shows the highest OPV power conversion efficiency; this is due to the lowest CTE binding energy for this blend that results from the most suitable D- and A- grain sizes. We also show that the exciton lifetime is the shortest for the optimum blend, and this helps boosting the device efficiency by reducing energy loss.