“Special Issue on Latin-American Research” Maritime Networks,Services Structure and Maritime Trade

This paper aims at investigating the relationship between maritime trade and maritime freight rates at sectoral level. These rates and their effect on international trade will be estimated using highly disaggregated data of shipments from five Spanish ports to seventeen destinations, 78.34% of the tonnage exported by Spain. The paper focuses on the effect of maritime networks, services structure and port infrastructure variables on maritime freight rates. The relationship between freight rates and trade is then analysed by applying a gravity model for sectoral exports. We investigate the endogeneity of the trade and freight rate variables by estimating both equations by using instrumental variables methods. The main findings of this study should contribute significantly in explaining the variability of maritime freight rates and to quantifying the impact of maritime freight rates in maritime trade.     

Fired clay masonry units production incorporating two-phase olive mill waste (alperujo)

This work deals with the use of alperujo, the main residue from the two-phase olive oil extraction process, as a raw material in fired clay masonry units production. Different amounts (3, 6 and 12 wt%) of clay were substituted by alperujo, and the properties of the resulting ceramic units were compared to those of conventional products. Results show that a number of advantages can be obtained. At 12 wt% alperujo addition, masonry units present lower density (1710 kg m^?3 compared to 1850 kg m^?3 reference value) and higher thermal insulation effectiveness (18% reduction in the bulk of fired clay thermal conductivity). With respect to mechanical properties, the fired bending strength attained of approximately 14 N mm^?2 is sufficiently high for this type of unit. In addition, the heating value obtained from the organic content of the added alperujo can cause a decrease in the heating requirements in the firing process.     

Magnetite Production from Steel Wastes with Concentrated Solar Energy

In order to achieve a balanced development in the application of materials for structural or functional purposes, one of the priority objectives of future work is to achieve the goal of “zero waste” in the different production lines. As would be expected from what was agreed in the Kyoto Protocol and the meetings of Copenhagen 2009 and Cancun 2010, the production of clean energy will be strongly encouraged in the future, and indeed that is already the case now. Taking that into consideration, while the promotion of clean energy production is mainly directed toward electricity, solar thermal is quite interesting because of its direct application to metal mining and the chemical processes used in the sustainable development of materials. The combination of both objectives, “zero waste” and “clean energy,” may pose an interesting challenge in the development of primary iron and steel, as well as in other areas of metal production and even in the field of mining. The help of solar thermal energy, which can be concentrated to reach high temperatures, is a tool that could support both the direct production and the recycling of waste steel, in particular waste which is physically and chemically the worst for the environment. This would mean that the environment itself, solar energy, is in fact the key to environmental protection.     

The influence of the process conditions on the characteristics of activated carbons obtained from PET de-polymerisation

In a previous paper we have reported a procedure to obtain active carbons by carbonisation of the residues obtained from the basic hydrolysis of poly(ethyleneterephthalate) (PET). Now we are getting insight into the relationships between the process parameters and the properties of the active carbons obtained by this procedure. Hydroxide/residue mass ratio, nitrogen flow rate, carbonisation time and carbonisation temperature are the process parameters which have been considered. It is shown that the textural properties of the activated carbons can be tailored by controlling such variables. Thus it is possible to obtain active carbons with a wide range of textural characteristics ranging from a molecular sieve to a sample with heterogeneous pore size but with high adsorption volume (0.8 cm³/g). This adds value to the procedure of obtaining active carbons from PET wastes. The textural characteristics have been determined by analysing the nitrogen and carbon dioxide adsorption isotherms. Several approaches have been applied to the isotherms, namely BET, Dubinin-Radushkevich, α_s-plot and molecular simulation. Our results also show that all the approximations render similar textural characteristics when the micropore network is narrow, uniform and accessible. Nevertheless, it seems the α_s-method overestimates micropore volumes in very activated carbons, as DR and molecular simulation render coincident values.     

A review: Energy recovery in batch processes

The implementation of batch processing has increased due to its intrinsic flexibility and adaptability. These are essential characteristics when it comes to producing high-value added materials such as agrochemicals, pharmaceuticals, specialty chemicals…the demand for which has grown in recent decades.Although industrial processes are highly diverse, a common feature to all is that they utilize fossil fuels as the energy source. The reliance on fossil fuels as a primary source of energy generates a negative impact on the environment. The implantation of renewable energies and efficient usage of energy has thus become crucial. Improving energy use could be achieved through advancements in plant machinery and the use of methodologies such as ‘process integration’.Process integration can be described as system oriented methods that could be used during the design and retrofit of industrial processes in order to obtain an optimal utilization of resources. The methods have traditionally focused on an efficient energy use, although recently process integration techniques cover other areas such as efficient use of raw materials, emission reduction and process operations. Energy integration tries to reach the optimization of heat, power, fuel and utilities.The consideration of energy integration complicates the process design and the generation of batch process design alternatives, so what is now required is the proposal and development of different approaches and methods oriented towards recovering energy in this kind of industrial process. Improving energy end-use efficiency will make it possible to reduce dependence on energy imports and bring about innovation and competitiveness.The aim of this work is report the main contributions that have been carried out in order to attain energy integration in batch processes, as well as different examples of applications that have shown the possibilities offered by the developed tools.     

Factors affecting growth of foodborne pathogens on minimally processed apples

Escherichia coli O157:H7, Salmonella and Listeria innocua increased by more than 2 log₁₀ units over a 24 h period on fresh-cut ‘Golden Delicious’ apple plugs stored at 25 and 20 °C. L. innocua reached the same final population level at 10 °C meanwhile E. coli and Salmonella only increased 1.3 log₁₀ units after 6 days. Only L. innocua was able to grow at 5 °C. No significant differences were observed between the growth of foodborne pathogens on fresh-cut ‘Golden Delicious’, ‘Granny Smith’ and ‘Shampion’ apples stored at 25 and 5 °C. The treatment of ‘Golden Delicious’ and ‘Granny Smith’ apple plugs with the antioxidants, ascorbic acid (2%) and NatureSeal^® (6%), did not affect pathogen growth. The effect of passive modified atmosphere packaging (MAP) on the growth of E. coli, Salmonella and L. innocua on ‘Golden Delicious’ apple slices was also tested. There were no significant differences in growth of pathogens in MAP conditions compared with air packaging of ‘Golden Delicious’ apple plugs, but the growth of mesophilic and psychrotrophic microorganisms was inhibited. These results highlight the importance of avoiding contamination of fresh-cut fruit with foodborne pathogens and the maintenance of the cold chain during storage until consumption.     

Fate of Escherichia coli O157:H7, Salmonella and Listeria innocua on minimally-processed peaches under different storage conditions

Consumption of fresh-cut produce has sharply increased recently causing an increase of foodborne illnesses associated with these products. As generally, acidic fruits are considered ‘safe’ from a microbiological point of view, the aim of this work was to study the growth and survival of Escherichia coli O157:H7, Salmonella and Listeria innocua on minimally-processed peaches. The three foodborne pathogens population increased more than 2 log₁₀ units on fresh-cut peach when stored at 20 and 25 °C after 48 h. At 10 °C only L. innocua grew more than 1 log₁₀ unit and it was the only pathogen able to grow at 5 °C. Differences in growth occurred between different peach varieties tested, with higher population increases in those varieties with higher pH (‘Royal Glory’ 4.73 ± 0.25 and ‘Diana’ 4.12 ± 0.18). The use of common strategies on extending shelf life of fresh-cut produce, as modified atmosphere packaging and the use of the antioxidant substance, ascorbic acid (2% w/v), did not affect pathogens’ growth at any of the temperatures tested (5 and 25 °C). Minimally-processed peaches have shown to be a good substrate for foodborne pathogens’ growth regardless use of modified atmosphere and ascorbic acid. Therefore, maintaining cold chain and avoiding contamination is highly necessary.