Evaluation of the antiradical and reducing properties of selected Greek white wines: correlation with polyphenolic composition

The total hydroxycinnamate (THC) and total flavanol (TF) contents were determined in 26 selected Greek white wines of ‘Appellation of Origin of High Quality’ using well‐established spectrophotometric methodology. Furthermore, two parameters related to the antioxidant capacity of wines, the antiradical activity (A_AR) and the reducing power (P_R), were also determined using the stable DPPH· radical and a ferric reducing power assay respectively. THC content varied from 64.4 to 197.1 mg l^?1 chlorogenic acid equivalents (CGAE), whereas TF content exhibited larger variation, ranging from 3.3 to 205.3 mg l^?1 catechin equivalents (CTE). A_AR and P_R were found to range from 0.47 to 0.60 mM Trolox equivalents (TRE) and from 0.32 to 2.05 mM quercetin equivalents (QE) respectively. Regression analysis at 95% significance level indicated that reducing effects are likely to be exerted by the flavanol fraction (SF < 0.05), as opposed to antiradical efficiency which is primarily affected by the sum of THC and TF contents (SF < 0.05), suggesting that synergistic phenomena account for the overall antioxidant status of white wines. © 2002 Society of Chemical Industry     

Comparing hybrid learning with traditional approaches on learning the Microsoft Office Power Point 2003 program in tertiary education

The purpose of this study was to determine the effectiveness of a hybrid learning approach to deliver a computer science course concerning the Microsoft office PowerPoint 2003 program in comparison to delivering the same course content in the form of traditional lectures. A hundred and seventy-two first year university students were randomly assigned into two teaching method groups: traditional lecture instruction (TLI) and hybrid lecture instruction (HLI). Each group received six 95-min periods of instruction divided into 4 sections: a) 5-min brief outline of the key learning points, b) 40-min lecture on general knowledge c) 45-min constructivist-inspired learning activities and d) 5-min summary on key learning points. In the beginning and the end of this study students completed a 17-item multiple choice knowledge test. Two-way analysis of variances (ANOVA), with repeated measures on the last factor, were conducted to determine effect of method groups (TLI, HLI) and measures (pre-test, post-test) on knowledge test. The measures main effect was significant, as well as the groups x measures interaction effect. Two independent-samples t test were conducted to follow up the significant interaction. Differences in mean ratings of knowledge performance between the two teaching groups were not significantly different at first measure, while the TLI method group yielded a significantly lower mean rating at second measure. The findings indicated that HLI approach might be a superior option for undergraduate students on learning the Microsoft office PowerPoint 2003 program.     

Study of the thermal behaviour of alipharomatic polyesters around the glass–rubber transition region by thermomechanical analysis: the mobile and rigid amorphous fraction

The objective of this work was the study using thermomechanical analysis (TMA) of a peculiar behaviour, which was observed some years ago, around the glass–rubber transition region in some thermoplastic alipharomatic polyesters. For this purpose a series of nine alipharomatic polyesters was prepared by the two‐stage melt polycondensation method in a glass batch reactor and subjected to TMA in both penetration and expansion mode. Differential scanning calorimetry (DSC) was additionally used and the results are discussed focusing mainly on the first derivative curve of TMA thermograms in the penetration mode. From this curve, which shows two distinct peaks, the first peak could be attributed to the glass transition temperature (T_g) of the mobile amorphous fraction, since the value coincides with that obtained from DSC and is due to the abrupt shrinkage of the amorphous part of the sample. The second peak (up to 40 °C higher than T_g) is due most probably to the softening of the rigid amorphous fraction and the passage of the polymeric sample from the glass region to the cold crystallization region. When the sample is more crystalline than amorphous then the first peak is smaller or is completely absent. Copyright © 2006 Society of Chemical Industry     

Water supply management approaches using US on the island of Rhodes, Greece

Desalination powered by renewable energy sources (RES) is presented as an alternative option for the water supply augmentation in the semi-arid region of the island of Rhodes. The case study was chosen as the island relies mostly on the exploitation of groundwater resources and faces serious water shortage problems in an already stressed environment. Alternatives are discussed and compared in contrast to the construction of storage dams to meet urban water needs up to the year 2040. Results may indicate that through the use of financial incentives coupled with holistic water management approaches, desalination powered by RES could be an attractive and environmentally friendly option in an effort to solve problems related to water quantity and quality in semi-arid regions with adequate renewable energy potential.     

Magnetic carbon nanotubes with particle-free surfaces and high drug loading capacity

Open-ended, multi-wall carbon nanotubes (CNTs) with magnetic nanoparticles encapsulated within their graphitic walls (magCNTs) were fabricated by a combined action of templated growth and a ferrofluid catalyst/carbon precursor, and tested as drug hosts. The hybrid nanotubes are stable under extreme pH conditions due to particle protection provided by the graphitic shell. The magCNTs are promising for high capacity drug loading given that the magnetic functionalization did not block any of the active sites available for drug attachment, either from the CNT internal void or on the internal and external surfaces. This is in contrast to typical approaches of loading CNTs with particles that proceed through surface attachment or capillary filling of the tube interior. Additionally, the CNTs exhibit enhanced hydrophilic character, as shown by water adsorption measurements, which make them suitable for biological applications. The morphological and structural characteristics of the hybrid CNTs are evaluated in conjunction to their magnetic properties and ability for drug loading (diaminophenothiazine). The fact that the magnetic functionality is provided from 'inside the walls' can allow for multimode functionalization of the graphitic surfaces and makes the magCNTs promising for targeted therapeutic applications.     

Modular construction of P3HT/PCBM planar-heterojunction solar cells by lamination allows elucidation of processing–structure–function relationships

Contrary to polymer solar cells with bulk-heterojunction active layers, devices with planar-heterojunction active layers allow the decoupling of active layer phase separation from constituent crystallization, and their relative influence on device performance. We fabricated planar-heterojunction devices by first processing the electron donor and electron acceptor in isolation; they were subsequently laminated across the donor–acceptor interface to establish electrical contact. Thermal annealing was intentionally avoided after lamination to maintain the pristine charge transfer interface. Lamination thus obviates the need for solvent orthogonality; more importantly, it provides independent process tuning of individual organic semiconductor layers, ultimately allowing control over constituent structural development. We found the short-circuit current density of planar-heterojunction solar cells comprising poly(3-hexyl thiophene), P3HT, and [6,6]-phenyl-C₆₁-butyric acid methyl ester, PCBM, as the electron donor and acceptor, respectively, to be generally independent of the annealing history of P3HT. On the contrary, thermal annealing PCBM prior to lamination mainly led to a reduction in short-circuit current density. This deterioration is correlated with the development of preferentially oriented PCBM crystals that hinders electron transport in the vertical direction.     

Screw dislocation in nonlocal anisotropic elasticity

Based on Eringen’s model of nonlocal anisotropic elasticity, new solutions for the stress fields of screw dislocations in anisotropic materials are derived. In the theory of nonlocal anisotropic elasticity the anisotropy is twofold. The anisotropic material behavior is not only included in the anisotropy of the elastic stiffness properties, but also in the anisotropy of the nonlocality which is expressed by the anisotropy of the length scale parameters, which is incorporated in the anisotropy of the nonlocal kernel function. Particularly, a new two-dimensional anisotropic kernel which is the Green function of a linear differential operator with three length scale parameters is derived analytically. New solutions for the stresses of straight screw dislocations in anisotropic (monoclinic and hexagonal) materials are found. The stresses do not have singularities and possess interesting features of anisotropy, which are presented and discussed.     

Water demand management: implementation principles and indicative case studies

Current practices for the efficient use and management of water resources are based on the conjunctive application of water supply and demand measures. Even though options for the augmentation of water supply are widely analysed and assessed, water demand management remains an open field for study, as it is highly dependent on the socio‐economic features of a region and has a site‐specific character. This paper summarizes the guiding principles of demand management and presents some successful application examples of demand management measures from regions that cover a wide range of socioeconomic and environmental conditions in an effort to identify the critical factors for the efficient planning and implementation of demand management plans.     

Estimating energy conservation patterns of Greek households

This paper develops an empirical model to investigate the main determinants of household energy conservation patterns in Greece employing cross-section data. In the empirical analysis, household energy-conserving choices models are employed, using a discrete and a latent trait variable respectively as a dependent variable. The results show that socio-economic variables such as consumers’ income and family size are suitable to explain differences towards energy conservation preferences. In addition, the results suggest that electricity expenditures and age of the respondent are negatively associated with the number of energy-conserving actions that a consumer is willing to adopt. Finally, other variables such as environmental information feedback and consciousness of energy problems are characteristics of the energy-saver consumer. By evaluating consumer's decision-making process with regards to energy conservation measures, we are able to formulate and propose an effective energy conservation framework for Greece. An energy policy framework is among the main prerequisites not only to achieve sustainable development but also to maintain consumers’ quality of life.     

A Model Based on the Assessment of Intrinsic Creep Resistance Concept

In the present study a simple model is proposed to assess creep behavior. The model is applied to experimental results performed on austenitic steel X8 CrNiMoNb 16 16. The model is based on a modification of the Levy‐Mises equation for plasticity to consider creep time effects, introducing as a parameter the intrinsic creep resistance. The assessment of creep behavior applied for monotonic and two stages loading data is good. The model could assess negative creep strain rates as well as damage accumulation observed as an increase of the minimum creep rate after each reloading at the same stress level in two stages tests.