A FRAMEWORK FOR SHARING ONLINE LABORATORY RESOURCES

ABSTRACT Numerous online laboratory resources have been and continue to be developed by many educational institutions around the world. These resources include both remote laboratories, which are based on actual experimental devices accessed remotely, as well as virtual laboratories, which represent software simulations of experiments. In the vast majority of the cases, the remotely accessible online laboratories reported on in the literature represent stand-alone systems, which are typically difficult to share by large numbers of learners dispersed at various educational institutions. This has led to the existence of many functionally similar, but independently operating systems developed in many places. This paper will identify the common features of such online laboratory resources. Then, the framework for a network of interconnected resource managers, which facilitate the efficient implementation and deployment of as well as the subsequent search for and shared usage of online laboratory resources (e.g. remote experiments, virtual experiments, game-based environments, etc.), will be presented. A centralized resource repository is presented that enables the publishing of information on the existence and availability of specific resources through the network. Finally, an example is given that illustrates the issues relating to joining, publishing, searching for and accessing online laboratory resources in that framework

Evaluation of low-rank coals as raw material for Fe and Ca organomineral fertilizer using a new EDXRF method

A rapid and reliable method for analyzing Fe and Ca in low-rank Greek coals was developed. The presence of Fe and Ca is of importance regarding the potential use of these coals as raw material for organomineral fertilizers. Samples were collected from the main Greek lignite deposits and standards were prepared using Atomic Absorption Spectroscopy (AAS), which were also employed in the Energy Dispersive X-ray Fluorescence (EDXRF) method. The new method offers the advantages of being timesaving, non-destructive and can be easily incorporated in a fertilizer production line. Analysis of low-rank Greek coals demonstrated a significant Fe and Ca content ranging from 0.15 to 1.97 wt.% for Fe and from 0.04 to 2.51 wt.% for Ca. When both EDXRF and AAS techniques were applied, the Fe and Ca concentration values differed less than 5%, demonstrating that both techniques are reliable for low-rank coals in the above concentration range. These EDXRF results may be used as a preliminary test regarding the application of Greek coals in organomineral fertilizer production, given that in these coals iron and calcium are the most abundant metals. © 2008 Elsevier B.V. All rights reserved

Chemistry of metal-humic complexes contained in Megalopolis lignite and potential application in modern organomineral fertilization

Lignite samples from two deposits located in the Megalopolis Basin, Southern Greece, were evaluated for their potential applicability as raw materials for the production of organomineral fertilizers. Fundamental chemical analyses were carried out to demonstrate high humic substances and metal contents. To determine their relative distribution in the Megalopolis lignite extract, eight elements, namely Na, K, Cd, Mn, Mg, Pb, Zn, and Cu, were studied both in H2O and in Na4P2O7/NaOH solutions. The behavior of these metals showed significant variations; Zn, Pb, Cd, and Cu associate mostly to the humic substances and proved scarce in the water extract. Contrarily, K and Mg gave a significantly low total yield in the Na4P2O7/NaOH solution, while Mn was classified among the least extracted elements. Further enrichment of Megalopolis humic substances in these metals was achieved; Pb and Mg proved the most and least retained metal, respectively. Decomplexation titration curves of humic matter saturated with these metal ions demonstrated that novel organomineral fertilizing materials may develop based on optimized metal ion and humate contents, which can retain metals in a soluble form within a wide pH range. Formation of complexes between humic substances and Zn, Cd, and Mg was clearly indicated. © 2009 Elsevier B.V. All rights reserved

Studies of the low-rank Greek coals. 1. Classification

Physical and chemical measurements of Greek coals lead to a classification by rank into five categories, ranging from subbituminous C to peat. This classification is further documented by ESR spectroscopy and powder X-ray diffraction. In order to accommodate all the deposits, a new category is introduced between lignite B and peat, designated as lignitized peat, which is clearly and operationally distinguished from peat and higher-rank lignites. © 1989

Fe(III)-humate complexes from Megalopolis peaty lignite: A novel eco-friendly fertilizer

Fe(III)-humate complexes were synthesized from Greek peaty lignite of the Megalopolis Basin. The preparation was carried out under mild and low-energy conditions producing a biodegradable, eco-friendly and effective material to substitute the synthetic chelates Fe-EDDHA, Fe-EDTA and Fe-DTPA. Due to both the existing expanded configuration of the humic substances (that make binding sites accessible to the metal ions) and the ionization of functional groups, alkaline environment facilitates the association between Fe(III) ions and the lignite-derived humic substances. UV-vis and IR spectra revealed coordination of the metal ions with the carboxylic and phenolic groups of the oxygen-rich humic substances. Fe(III)-humate complexes were proved stable in a wide pH range similar to Fe-EDDHA synthetic chelates. Furthermore, the presence of K+ and humic matter increases the agronomic value of this material establishing alternative applications for Megalopolis peaty lignite. © 2009 Elsevier Ltd. All rights reserved

Innovative biocatalytic production of soil substrate from green waste compost as a sustainable peat substitute

In the present work, a new simple and quick eco-friendly method is discussed to handle effectively the green wastes and produce a sustainable peat substitute of high quality on the large scale. Principal physicochemical parameters, i.e., temperature, moisture, specific weight, pH, electrical conductivity and, also, microorganisms, organic matter, humic substances, total Kjeldahl nitrogen and total organic carbon, C/N ratio, ash, metal content and phytotoxicity, were monitored systematically. Humic substances content values were interrelated to both C/N ratio and pH values and, similarly, bulk density, TOC, TKN, C/N, GI, ash and organic matter were found interconnected to each other. A novel biocatalyst, extremely rich in soil microorganisms, prepared from compost extracts and peaty lignite, accelerated the biotransformation. Zeolite was also employed. The compost does not demonstrate any phytotoxicity throughout the entire biotransformation process and has increased humic substances content. Both humic substances content and germination index can be employed as maturation indices of the compost. Addition of compost, processed for 60 days only, in cultivations of grass plants led to a significant increase in the stem mass and root size, annotating the significant contribution of the compost to both growth and germination. The product obtained is comparable to peat humus, useful as peat substitute and can be classified as a first class soil conditioner suitable for organic farming. © 2016 Elsevier Lt

Design and Implementation of a Virtual Laboratory for Machine Dynamics

Laboratory experiments are considered to be a crucial component of engineering and science curricula by all stakeholders in the education process. In traditional laboratories, students develop practical skills and become effective professionals. However, the major drawbacks of traditional laboratories are their high demand on resources, significant maintenance costs and the inability to delivery the laboratory content in distance education. Virtual laboratory experiments represent a valuable option for educational laboratories, due to their advantages over traditional hands-on as well as remote experiments, including the ease of reconfiguring the experimental system, the high flexibility in the input specifications, the possibility of conducting experiments using devices otherwise infeasible and the option of re-running experiments multiple times. In response to the need for developing laboratory resources that provide a practical experience to online engineering students, this paper describes a simulation-based virtual laboratory, which is used at Stevens Institute of Technology (SIT) in a junior-level course on mechanisms and machine dynamics as a compliment to experimental work in the traditional hands-on laboratory. This virtual laboratory system alleviates the space, time and cost constraints associated with traditional laboratories and serves as an efficient teaching aid. It conveys to the students practical issues associated with actual experiments and provides learning outcomes that are comparable to those of traditional physical laboratories. The students have the opportunity to explore a wide range of experimental configurations and parameters. In addition, the system includes a realistic rendering of the experimental setup and its components, thus providing the students with a strong feeling of immersion, as if they were performing an experiment in a traditional laboratory

Preparation of bioinorganic fertilizing media by adsorption of humates on glassy aluminosilicates

Surface-modified expanded perlite was synthesized using humic substances from the Megalopolis peaty lignite. Adsorption is efficient and increases at higher temperatures and lower pHs. The preparation can be carried out under mild conditions leading to an eco-friendly, bioinorganic material useful as soil conditioner and biofertilizer. Six adsorption models were applied; the Klotz, Freundlich and Redlich-Peterson isotherms fit more successfully to the experimental data. The obeying of the theoretical models was correlated with the heterogeneity and non-uniform distribution of the adsorption sites, host-guest attraction forces as well as the formation of self-assembled aggregates and self-organized multilayers of humic substances onto the aluminosilicate adsorbent, consistent with changes in micromorphology. Thermodynamic quantities revealing distinct physicochemical characteristics of the adsorption phenomena, i.e., enthalpy, entropy and free energy change, were calculated. Desorption experiments and cultivation of microorganisms demonstrated that perlite may act successfully as host material for microbial populations upgrading the humic-loaded perlite for soil applications. © 2010 Elsevier B.V

Dispersion and sorption of oil spills by emulsifier-modified expanded perlite

Three grain sizes of expanded perlite were modified with emulsifiers and their potential usefulness in combating oil spills was studied. The tests in the laboratory show that when this perlite is added to a water-oil mixture, the light perlite particles move on the surface spreading over it very quickly (in fractions of a second). It seems that the emulsifier disperses the oil, but at the same time it disperses the perlite particles. At the end there is an emulsion and also perlite particles saturated with it. The usefulness in combating oil spills at sea depends on the following characteristics: (a) With emulsifier-modified perlite some of the oil can be removed (in the form of emulsion), whereas with emulsifiers only this is not possible. Simultaneously the spill is dispersed quickly, before spreading. (b) The action is quick even with a calm sea. Self-mixing is inherent to the process. (c) The action is quick and limited to the surface, where the perlite particles float. There is little waste of the emulsifier in the bulk of the sea. © 2002 Elsevier Ltd. All rights reserved