Tunable and white light photoluminescence from ZnO on porous Si with the addition of carbon quantum dots.

In this work we demonstrate a two-pixel solid-state photoluminescent device able to emit white light covering the entire visible spectrum from 380 nm up to 800 nm. The device is based on a combination of porous Si, hydrothermally grown ZnO and carbon quantum dots, in a two-pixel formation, with porous Si and ZnO acting independently while the carbon quantum dots are deposited on top of the entire device. All processing is done using standard Si processing techniques. Moreover, the device design allows for tunability of the emitted spectrum simply by choosing the desired combination of the materials. Overall, the demonstrated device is low cost, environmentally safe and biocompatible.

Two-terminal charge-trapping WORM memory device using anodic aluminum oxide.

A two terminal write-once-read-many-times (WORM) memory device based on charge trapping near the interface of anodic aluminum oxide and p+Si is demonstrated. An investigation of the memory properties as a function of the interface morphology is presented. A memory window, defined as the ratio of current before and after the application of a given "write" pulse, of the order of 100 was demonstrated for the best devices studied. The devices also exhibited good stability with time both in terms of retention and in terms of measuring cycles in the "written" state. A variation of the results by less than 10% over 50 measured devices is reported. The current through the devices is analyzed and the mechanisms behind the observed behavior are discussed in detail.

Decision support system for the evaluation of urban air pollution control options: application for particulate pollution in Thessaloniki, Greece.

Development of strategies to control urban air pollution is a complex and multi-disciplinary process involving a wide range of scientists with different expertise and interests. This paper presents an integrated assessment methodological scheme for the evaluation of air pollution control measures that are put forward in order to reduce sufficiently air pollution levels in urban areas. Forming long-term, efficient air pollution control strategies requires knowledge of the costs associated with their implementation, the emission inventories and emission reductions to be achieved, as well as the concentration variations that represent air quality levels in the area examined. In contrast to the majority of the currently employed assessment approaches, the presented scheme enables the evaluation of any proposed air pollution control option in terms of its combined impact on air quality and social welfare, by correlating economic and health impact assessment issues. The approach presented in this paper brings together air quality modelling and mathematical programming techniques and provides a decision support system for the determination of optimal bundles of air pollution control options according to the particular features and needs of the areas examined. Both cost-effectiveness and cost-benefit approaches are taken into account in order to put the problem on the basis of economic efficiency from a societal perspective. The methodology is implemented for the case of Thessaloniki, Greece, which is selected on the grounds that the area is considered as one of the most polluted--if not the most polluted--cities within Europe, especially with respect to airborne particles.

Air quality status in Greater Thessaloniki Area and the emission reductions needed for attaining the EU air quality legislation.

This paper aims at imprinting the urban air quality status and assessing the impact of various emission reduction scenarios on the photochemical and particulate matter air pollution levels in the Greater Thessaloniki Area, Greece. In particular, it is investigated under which conditions compliance with the EU air quality legislation can be achieved. For this purpose, the Ozone Fine Structure model is applied for a full calendar period (reference year 2002), as well as for specific scenarios, corresponding to predefined emission reductions for 2010. The model results for photochemical and particulate matter air pollution levels in 2002 agree fairly well with the observations. Predictions for 2010 indicate that significant improvement towards the EU legislation requirements can be achieved for certain emission reduction scenarios. However, an overall strategy will also have to include additional local scale measures.