Simulating Future Groundwater Recharge in Coastal and Inland Catchments

Groundwater is a primary source of drinking water in the Mediterranean, however, climate variability in conjunction with mismanagement renders it vulnerable to depletion. Spatiotemporal studies of groundwater recharge are the basis to develop strategies against this phenomenon. In this study, groundwater recharge was spatiotemporally quantified using the Soil and Water Assessment Tool (SWAT) in one coastal and one inland hydrological basin in Greece. A double calibration/validation (CV) procedure using streamflow data and MODIS ET was conducted for the inland basin of Mouriki, whereas only ET values were used in the coastal basin of Anthemountas. Calibration and simulation recharge were accurate in both sites according to statistical indicators and previous studies. In Mouriki basin, mean recharge and runoff were estimated as 16% and 9%, respectively. In Anthemountas basin recharge to the shallow aquifer and surface runoff were estimated as 12% and 16%, respectively. According to the predicted RCP 4.5 and 8.5 scenarios, significant variations in groundwater recharge are predicted in the coastal zone for the period 2020–2040 with average annual recharges decreasing by 30% (RCP 4.5) and 25% (RCP 8.5). Variations in groundwater recharge in the inland catchment of Mouriki were insignificant for the simulated period. Anthemountas basin was characterized by higher runoff rates. Groundwater management in coastal aquifers should include detailed monitoring of hydrological parameters, reinforced groundwater recharge during winter and reduced groundwater abstraction during summer depending on the spatiotemporal distribution of groundwater recharge.

     

Effects of Genetic, Pre- and Post-Harvest Factors on Phenolic Content and Antioxidant Capacity of White Asparagus Spears

The effects of genetic, pre-harvest (season of harvest, spear diameter, spear portion and spear tip color) and post-harvest factors (storage and domestic preparation practices, e.g., peeling and cooking) on total phenolic, flavonoid and ascorbic acid content of white asparagus spears and their correlation with antioxidant capacity (DPPH and FRAP) were studied. Results showed that genetic material was important for the total phenolic content but not season of harvest, spear diameter or storage. Violet spear tips and apical spear portions showed the largest amount of total phenolics. Peeling did not affect total phenolics in fresh asparagus, whereas it reduced their content in stored asparagus, while cooking resulted in an increase in both fresh and stored asparagus. However, the soluble extract of total phenolics and flavonoids were minor and the missing significance of phenolics and flavonoids in antioxidant capacity of white asparagus spears depends on these small amounts.     

Bubble columns with fine pore sparger operating in the pseudo-homogeneous regime: Gas hold up prediction and a criterion for the transition to the heterogeneous regime

New experimental data concerning the gas holdup in bubble columns equipped with porous sparger were acquired. The effect of liquid properties and sparger characteristic (i.e., pore size, dimensions) on gas holdup at the pseudo-homogeneous regime has been studied and a correlation regarding the prediction of the transition point from the pseudo-homogeneous to the heterogeneous regime has been proposed and found to be in good agreement with available data. Moreover, a previously proposed correlation [Mouza, A.A., Dalakoglou, G.K., Paras, S.V., 2005. Effect of liquid properties on the performance of bubble column reactors with fine pore spargers. Chemical Engineering Science 60(5), 1465-1475], for the prediction of gas holdup at the homogeneous regime for this type of equipment, has been modified to take into account the effect of the mean pore diameter and it is also found to be in good agreement with published data.     

Adjustable Hyperthermia Response of Self‐Assembled Ferromagnetic Fe‐MgO Core–Shell Nanoparticles by Tuning Dipole–Dipole Interactions

The Fe‐MgO core‐shell morphology is proposed within the single‐domain nanoparticle regime as an enhanced magnetically driven hyperthermia carrier. The combinatory use of metallic iron as a core material together with the increased particle size (37–65 nm) triggers the tuning of dipolar interactions between particles and allows for further enhancement of their collective heating efficiency via concentration control. A theoretical universal estimation of hysteresis losses reveals the role of dipolar interactions on heating efficiency and outlines the strong influence of coupling effects on hyperthermia opening a novel roadmap towards multifunctional heat‐triggered theranostics particles.     

Coalescence during bubble formation at two neighbouring pores: An experimental study in microscopic scale

This work studies the effect of the liquid properties and the operating conditions on the interactions between under-formation bubbles in a cell equipped with two adjacent micro-tubes (i.d. ) for the gas injection, placed 210, 700 and apart. This set-up simulates, though in a simplified manner, the operation of the porous sparger in a bubble column, and it is used to study the bubble interactions observed on the sparger surface. Various liquids covering a wide range of surface tension and viscosity values are employed, while the gas phase is atmospheric air. A fast video recording technique is used both for the visual observations of the phenomena occurring onto the tubes and for the bubble size measurements. The experiments reveal that the interactions between under-formation bubbles as well as the coalescence time depend strongly on the liquid properties, the distance between the tubes and the gas flow rate. Two correlations, which can be found helpful for the bubble column design, have also been formulated and are in good agreement with the available experimental data.     

Non-lactic acid, contaminating microbial flora in ready-to-eat foods: a potential food-quality index

The bacteriological profile of 87 samples of commercially available ready-to-eat (RTE) dairy and meat-products, packaged sandwiches and salads was obtained by testing for aerobic colony count, for lactic acid bacterial (LAB) count, for the presence and the extent of non-LAB microflora (contaminating microflora), and by testing for certain food-borne pathogens. The pathogens Listeria monocytogenes, Salmonella spp. and sulfite-reducing clostridia were not detected in any of the analysed samples. Whereas only three samples (3.4%) were deemed unacceptable for consumption for exceeding the established pathogen tolerance levels (for Staphylococcus aureus and Escherichia coli), several samples were found to contain non-lactic acid contaminating microflora of considerable magnitude. The log10 cfu g(-1) counts for contaminating microflora in the food categories examined were as follows: hard cheeses 4.85 (SD 1.17); semi-hard cheeses 5.39 (SD 1.37); soft cheeses 5.13 (SD 1.03); whey cheeses 6.55 (1.24); fermented meat-products 4.18 (SD 1.48); heat-treated meat-products 3.47 (SD 1.99); salads 3.37 (SD 1.56) and sandwiches 5.04 (SD 0.96). Approximately 1 in every 30 to 80 bacterial cells found on different types of cheeses and salads was a non-LAB microorganism; the respective ratios for fermented meat-products, heat-treated meat-products and sandwiches were 1 in 6, 2.5 and 15. The assessment of the contaminating microflora magnitude at various steps during the manufacture and distribution of RTE foods can serve as an index for monitoring the microbiological quality of the starting materials, the sanitation efficacy during processing and possible temperature abuse during processing, transportation or storage.     

Mobility,education and labor market outcomes for U.S. graduates: Is selectivity important?

The literature on human capital, and its positive effects on individuals and regional economies, is now vast. The linkages between human capital and migration have also found a fertile ground in recent years especially in Europe where many studies have focused on interregional migration of graduates and highly skilled individuals. However, the literature on this phenomenon in the USA is less developed. Using the SESTAT database from NSF, this paper aims at contributing to the understanding of inter-state migration behavior of graduates in the USA and its effects on their career outcomes. It builds on the existing literature not only by focusing specifically on the US context, but also incorporating into the empirical model a correction for the possible selection bias that arises from the dual relationship between migration propensity and human capital endowment. Our estimated Mincerian earning equations, corrected for migrant self-selectivity, show that indeed repeat migration is associated with higher average salaries, while late migration is associated with a salary penalty. As for the other control variables, our results are consistent with what has been found in the labor economics literature. Female workers suffer from a salary penalty, while experience, level of education and employer size are all associated with higher average salaries. The labor market also rewards different fields of study differently.     

Evaluating the research performance of the Greek medical schools using bibliometrics

Quality in Higher Education Institutions is the subject of several debates in the academic community in a worldwide basis and various efforts are made towards identifying ways to quantify it. In this respect, the use of bibliometrics gains significant ground as an effective tool for the evaluation of universities’ research output. In the present study, the research performance of the seven Greek medical schools is assessed by means of widely accepted and advanced bibliometric indices, such as total and average publications and citations, average and median h- and g-index with and without self-citations for all the 1,803 academics, while statistical analysis of the data was also performed in order to compare the observed differences in the mean values of the calculated indices. Considerable effort was exerted to overcome all inherent limitations of a bibliometric analysis through a meticulous data collection. This large-scale work was conducted both in school and academic rank level leading to interesting results concerning the scientific activity of the medical schools studied as units and of the various academic ranks separately, which can be partially justified with geographic and socioeconomic criteria. In general, bibliometrics demonstrate statistically significant difference in favour of Crete University medical school, while it was also found that self-citations have only marginal effect on the individual’s research profile and the average indices. Finally, the useful findings of the present study render the methodology adopted of high viability for assessing the research performance of Higher Education Institutions even in a broader context.     

Effect of organic surfactant additives on gas holdup in the pseudo-homogeneous regime in bubble columns equipped with fine pore sparger

New experimental data concerning the gas holdup in bubble columns equipped with porous sparger were acquired. The effect of surfactant additives on gas holdup in the pseudo-homogeneous regime has been studied. Three different commercial surfactants (Triton X-100^®, SDS^®, CTAB^®) were used and four aqueous solutions of each one were employed, in order to study the effect of the surfactant concentration and type (i.e., non-ionic, anionic, cationic). A general correlation, which includes dimensionless numbers (i.e., Froude, Archimedes and Bond) as well as the geometric characteristics of the column and the sparger, can predict the gas holdup in various systems (i.e., pure substances, ionic surfactants, non-ionic surfactants) with reasonable accuracy.     

Bibliometric evaluation of the research performance of the Greek civil engineering departments in National and European context

Quality evaluation and its assurance in higher education institutions constitute an obligation and scope of most European Universities. To accomplish this, quantitative indices, known as bibliometrics, are recruited which are considered a useful evaluation tool particularly for academics’ and Universities’ research performance. In the present study, the research quality of the five Greek civil engineering departments (Athens, Patras, Thessaloniki, Volos, Xanthi) is assessed by means of several advanced bibliometric indices calculated separately for each academic. Statistical analysis of the data is also performed to compare the observed differences in the mean values of the calculated indices. The study is conducted both in department and academic rank level to explore how research activity is distributed among the various ranks. In addition, to evaluate the research status of the Greek departments in the European context, their research output is compared with that of London civil engineering department. To explore the dependence of bibliometrics on seniority, bibliometric analysis considering the research activity of all academics only during the last decade is also made. Finally, the temporal progress of the research productivity leads to interesting findings about the impact of the European economic crisis on research performance. In general, bibliometrics demonstrate that Patras department host academics of better quality, but Athens exhibits higher scientific activity over the last decade. Superiority of London department is evident but few bibliometrics are comparable with the ones of the Greek departments. Results also indicate that no common standards in hiring/promotion of academics are established, while the European socio-economic crisis has significant negative impact on research productivity.