Degradation in soil behavior of artificially aged polyethylene films with pro‐oxidants

Bio‐based, biodegradable in soil, as well as degradable polyethylene mulching films with pro‐oxidants, have been introduced in the market in an effort to deal with the serious problem of managing plastic waste streams generated from conventional mulching films. In a previous experimental investigation, a series of naturally degraded under water melon cultivation conditions linear low density polyethylene (LLDPE) mulching films with pro‐oxidants, buried in the field for 8.5 years, were recovered intact even though undergoing a continuous slow abiotic degradation in soil. The aim of the present article was to simulate the behavior of the LLDPE mulching films with pro‐oxidants under a much longer time‐scale (e.g. some decades). Toward this purpose, samples of LLDPE with pro‐oxidants film were artificially degraded to simulate severe degradation/fragmentation of these films while been buried in the soil for many years, following the end of the cultivation season. Further degradation of these severely degraded samples was investigated by burying them in the soil over a period of seven years. During this burial period, all degradation parameters and their evolution with time were measured. The artificially degraded LLDPE film samples with pro‐oxidants, in contrast to the naturally degraded film that remained intact for 8.5 years, were gradually transformed into tiny micro‐fragments in the soil. These fragments, through a continuing abiotic degradation process under natural soil conditions are eventually transformed into invisible micro‐fragments. The fate of these micro‐fragments and their long‐term impact to the environment and human health is unpredictable. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42289.     

Effect of different iron compounds on wheat and gluten‐free breads

BACKGROUND: Iron fortification of bread often results in sub‐optimal quality of the final product due to undesirable changes in the physical characteristics and sensory properties of the bread. In this study both the form of iron (soluble, insoluble or encapsulated) and the type of bread (wheat or gluten‐free) were varied in order to investigate the effect of iron and gluten on the product characteristics. RESULTS: The effect of iron on the quality characteristics of the breads investigated depended on iron type, but not on iron solubility. Colour, crust firmness, specific volume, cell number and uniformity as well as aroma were the attributes that were mainly affected in iron‐enriched wheat bread. In some cases, specific volume was 30% lower than that of the control sample, while cell uniformity was significantly lower, as low as 50% of the control sample in some fortified samples. In gluten‐free breads, differences between unfortified and fortified samples included colour, crust firmness, cell number, ‘moisture’ odour, metallic taste and stickiness. In some cases, the sensory scores were better for fortified samples. CONCLUSIONS: Differences due to iron fortification were less pronounced in gluten‐free compared to wheat breads. The choice of the appropriate iron compound which will not cause adverse quality changes is still a challenge. Copyright © 2010 Society of Chemical Industry     

The Adoption of Mediterranean Diet Attenuates the Development of Acute Coronary Syndromes in People with the Metabolic Syndrome

Objectives  

In this work we investigated the effect of the consumption of the Mediterranean diet on coronary risk, in subjects with the metabolic syndrome.     

Gender issues in technology use: Perceived social support,computer self-efficacy and value beliefs,and computer use beyond school

In this study, we examined relations between outside school computer experiences, perceived social support for using computers, and self-efficacy and value beliefs about computer learning for 340 Greek elementary school boys and girls. Participants responded to a questionnaire about their access to computer use outside school (e.g. frequency of use and nature of activities), perceived parental and peer support, and computer self-efficacy and value beliefs. Although almost all students used computers outside school, there were significant gender differences in frequency and type of computer use. Also, boys reported more perceived support from their parents and peers to use computers and more positive computer self-efficacy and value beliefs than girls. Parental support and, to a lesser extent, peer support were the factors more strongly associated with boys’ and girls’ computer self-efficacy and value beliefs, while home computer access was not related to students’ motivation. Our findings highlight the role of socialization in the gender gap in computing and the need for research and educational interventions that focus on the social practices that communicate gendered expectations to young boys and girls.     

Transforming communicating X-machines into P systems

Tissue P systems (tPS) represent a class of P systems in which cells are arranged in a graph rather than a hierarchical structure. On the other hand, communicating X-machines (XMs) are state-based machines, extended with a memory structure and transition functions instead of simple inputs, which communicate via message passing. One could use communicating XMs to create models built out of components in a rather intuitive way. There are investigations showing how various classes of P systems can be modelled as communicating XMs. In this paper, we define a set of principles to transform communicating XMs into tPS. We describe the rules that govern such transformations, present an example to demonstrate the feasibility of this approach and discuss ways to extend it to more general models, such as population P systems, which involve dynamic structures.     

Precipitation Forecast Using Artificial Neural Networks in Specific Regions of Greece

In recent years, significant changes in precipitation regimes have been observed and these manifest in socio economic and ecological problems especially in regions with increased vulnerability such as the Mediterranean region. For this reason, it is necessary to estimate the future projected precipitation on short and long-term basis by analyzing long time series of observed station data. In this study, an effort was made in order to forecast the monthly maximum, minimum, mean and cumulative precipitation totals within a period of the next four consecutive months, using Artificial Neural Networks (ANNs). The precipitation datasets concern monthly totals recorded at four meteorological stations (Alexandroupolis, Thessaloniki, Athens, and Patras), in Greece. For the evaluation of the results and the ability of the developed prognostic models, appropriate statistical indexes such as the coefficient of determination (R ²), the index of agreement (IA) and the root mean square error (RMSE) were used. The findings from this analysis showed that the ANN’s methodology provides satisfactory precipitation totals in four consecutive months and these results are better results, than those obtained using classical statistical methods. A fairly good consistency between the observed and the predicted precipitation totals at a statistical significance level of p < 0.01 for the most of the examined cases has been revealed. More specifically, the Index of Agreement (IA) ranges between 0.523 and 0.867 and the coefficient of determination (R ²) ranges between 0.141 and 0.603. The most accurate forecasts concern the mean monthly and the cumulative precipitation for the next four consecutive months.     

Energy balance analysis of combined photovoltaic-diesel powered telecommunication stations

During the last years photovoltaic (PV) generators comprise a promising option for satisfying the electrification needs of both grid connected and isolated systems worldwide. At the same time, the mobile telecommunication (T/C) sector presents a vast growth that leads to the expansion of the respective networks even at the most remote of areas. In this context, there are numerous T/C stations that cannot appreciate connection to an electricity grid and thus cover their energy needs usually on the basis of oil-consuming diesel generators. On the other hand, replacement of the oil-based generation with PV-battery stand-alone configurations implies system over-sizing so as to obtain zero load rejections throughout the year. In an attempt to both reduce the amounts of oil consumed and downsize the PV-battery system, a hybrid PV-based stand-alone system, employing also a diesel engine and a battery bank, is currently proposed. System sizing is first undertaken for various scenarios of annual fuel consumption and panel tilt angle under the restriction of zero load rejection, while following, the main directions for obtaining optimum solutions are given. Finally, an extensive energy balance analysis of typical configurations also provided reflects the fact that such hybrid systems may support better utilization of the PV energy production and also reduce considerably the annual amounts of oil required for the diesel-only solution.     

Performance of Pilot-scale Constructed Floating Wetlands in the Removal of Nutrients and Pesticides

Aiming to evaluate the efficacy of constructed floating wetlands (CFW) in removing agrochemicals (nutrients and pesticides), a series of experiments were run continuously for a 16-week period in pilot-scale CFW systems to study the effect of two aquatic plant species (duckweed and water hyacinth) and climatic parameters. The CFW systems were loaded daily with agricultural polluted water containing a fertilizer and five pesticides, whose concentrations and removal efficiencies were measured in the experiments. Average nutrient and pesticide reductions varied from 27.4% to 83.6% and from 12.4% to 42.7%, respectively. The two plants performed almost equally well. High temperatures and increased solar radiation significantly contributed to increased removal performance. The results suggest the use of CFW systems as effective and low-cost agricultural pollution control technologies.

     

Effect of acid tolerance response (ATR) on attachment of Listeria monocytogenes Scott A to stainless steel under extended exposure to acid or/and salt stress and resistance of sessile cells to subsequent strong acid challenge

The aim of this study was to investigate the potential effect of adaptive stationary phase acid tolerance response (ATR) of Listeria monocytogenes Scott A cells on their attachment to stainless steel (SS) under low pH or/and high salt conditions and on the subsequent resistance of sessile cells to strong acid challenge. Nonadapted or acid-adapted stationary-phase L. monocytogenes cells were used to inoculate (ca. 10? CFU/ml) Brain Heart (BH) broth (pH 7.4, 0.5% w/v NaCl) in test tubes containing vertically placed SS coupons (used as abiotic substrates for bacterial attachment). Incubation was carried out at 16 °C for up to 15 days, without any nutrient refreshment. L. monocytogenes cells, prepared as described above, were also exposed to low pH (4.5; adjusted with HCl) or/and high salt (5.5% w/v NaCl) stresses, during attachment. On the 5th, 10th and 15th day of incubation, cells attached to SS coupons were detached (through bead vortexing) and enumerated (by agar plating). Results revealed that ATR significantly (p<0.05) affected bacterial attachment, when the latter took place under moderate acidic conditions (pH 4.5, 0.5 or 5.5% w/v NaCl), with the acid-adapted cells adhering slightly more than the nonadapted ones. Regardless of acidity/salinity conditions during attachment, ATR also enhanced the resistance of sessile cells to subsequent lethal acid challenge (exposure to pH 2 for 6 min; pH adjusted with either hydrochloric or lactic acid). The trend observed with viable count data agreed well with conductance measurements, used to indirectly quantify remaining attached bacteria (following the strong acid challenge) via their metabolic activity. To sum, this study demonstrates that acid adaptation of L. monocytogenes cells during their planktonic growth enhances their subsequent attachment to SS under extended exposure (at 16 °C for up to 15 days) to mild acidic conditions (pH 4.5), while it also improves the resistance of sessile cells to extreme acid treatment (pH 2). Therefore, the ATR of bacterial cells should be carefully considered when applying acidic decontamination strategies to eradicate L. monocytogenes attached to food processing equipment.