Showing papers by "University of Patras published in 2016"

Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications

Abstract: This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of π–π interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graph...

Additive manufacturing methods and modelling approaches: a critical review

Abstract: Additive manufacturing is a technology rapidly expanding on a number of industrial sectors. It provides design freedom and environmental/ecological advantages. It transforms essentially design files to fully functional products. However, it is still hampered by low productivity, poor quality and uncertainty of final part mechanical properties. The root cause of undesired effects lies in the control aspects of the process. Optimization is difficult due to limited modelling approaches. Physical phenomena associated with additive manufacturing processes are complex, including melting/solidification and vaporization, heat and mass transfer etc. The goal of the current study is to map available additive manufacturing methods based on their process mechanisms, review modelling approaches based on modelling methods and identify research gaps. Later sections of the study review implications for closed-loop control of the process.

Vegetation of Europe: hierarchical floristic classification system of vascular plant, bryophyte, lichen, and algal communities

Abstract: Aims: Vegetation classification consistent with the Braun-Blanquet approach is widely used in Europe for applied vegetation science, conservation planning and land management. During the long history of syntaxonomy, many concepts and names of vegetation units have been proposed, but there has been no single classification system integrating these units. Here we (1) present a comprehensive, hierarchical, syntaxonomic system of alliances, orders and classes of Braun-Blanquet syntaxonomy for vascular plant, bryophyte and lichen, and algal communities of Europe; (2) briefly characterize in ecological and geographic terms accepted syntaxonomic concepts; (3) link available synonyms to these accepted concepts; and (4) provide a list of diagnostic species for all classes. LocationEuropean mainland, Greenland, Arctic archipelagos (including Iceland, Svalbard, Novaya Zemlya), Canary Islands, Madeira, Azores, Caucasus, Cyprus. Methods: We evaluated approximately 10000 bibliographic sources to create a comprehensive list of previously proposed syntaxonomic units. These units were evaluated by experts for their floristic and ecological distinctness, clarity of geographic distribution and compliance with the nomenclature code. Accepted units were compiled into three systems of classes, orders and alliances (EuroVegChecklist, EVC) for communities dominated by vascular plants (EVC1), bryophytes and lichens (EVC2) and algae (EVC3). Results: EVC1 includes 109 classes, 300 orders and 1108 alliances; EVC2 includes 27 classes, 53 orders and 137 alliances, and EVC3 includes 13 classes, 24 orders and 53 alliances. In total 13448 taxa were assigned as indicator species to classes of EVC1, 2087 to classes of EVC2 and 368 to classes of EVC3. Accepted syntaxonomic concepts are summarized in a series of appendices, and detailed information on each is accessible through the software tool EuroVegBrowser. Conclusions: This paper features the first comprehensive and critical account of European syntaxa and synthesizes more than 100 yr of classification effort by European phytosociologists. It aims to document and stabilize the concepts and nomenclature of syntaxa for practical uses, such as calibration of habitat classification used by the European Union, standardization of terminology for environmental assessment, management and conservation of nature areas, landscape planning and education. The presented classification systems provide a baseline for future development and revision of European syntaxonomy.

Imbalanced-learn: A Python Toolbox to Tackle the Curse of Imbalanced Datasets in Machine Learning

Abstract: Imbalanced-learn is an open-source python toolbox aiming at providing a wide range of methods to cope with the problem of imbalanced dataset frequently encountered in machine learning and pattern recognition. The implemented state-of-the-art methods can be categorized into 4 groups: (i) under-sampling, (ii) over-sampling, (iii) combination of over- and under-sampling, and (iv) ensemble learning methods. The proposed toolbox only depends on numpy, scipy, and scikit-learn and is distributed under MIT license. Furthermore, it is fully compatible with scikit-learn and is part of the scikit-learn-contrib supported project. Documentation, unit tests as well as integration tests are provided to ease usage and contribution. The toolbox is publicly available in GitHub: this https URL.

The Unreasonable Fairness of Maximum Nash Welfare

Abstract: The maximum Nash welfare (MNW) solution --- which selects an allocation that maximizes the product of utilities --- is known to provide outstanding fairness guarantees when allocating divisible goods. And while it seems to lose its luster when applied to indivisible goods, we show that, in fact, the MNW solution is unexpectedly, strikingly fair even in that setting. In particular, we prove that it selects allocations that are envy free up to one good --- a compelling notion that is quite elusive when coupled with economic efficiency. We also establish that the MNW solution provides a good approximation to another popular (yet possibly infeasible) fairness property, the maximin share guarantee, in theory and --- even more so --- in practice. While finding the MNW solution is computationally hard, we develop a nontrivial implementation, and demonstrate that it scales well on real data. These results lead us to believe that MNW is the ultimate solution for allocating indivisible goods, and underlie its deployment on a popular fair division website.

A global map of roadless areas and their conservation status

Abstract: Roads fragment landscapes and trigger human colonization and degradation of ecosystems, to the detriment of biodiversity and ecosystem functions. The planet’s remaining large and ecologically important tracts of roadless areas sustain key refugia for biodiversity and provide globally relevant ecosystem services. Applying a 1-kilometer buffer to all roads, we present a global map of roadless areas and an assessment of their status, quality, and extent of coverage by protected areas. About 80% of Earth’s terrestrial surface remains roadless, but this area is fragmented into ~600,000 patches, more than half of which are

Human–robot interaction review and challenges on task planning and programming

Abstract: The wide interest of research and industry in the human–robot interaction HRI related topics is proportional to the increased productivity and flexibility of the production lines, as it combines human and robot capabilities. This paper presents a review of recent research and progress on HRI, related to task planning/coordination and programming with emphasis on the manufacturing/production environment. Human–robot task allocation and scheduling, metrics for HRI, as well as the social aspects are reviewed. The role of digital human modelling systems for human–robot task planning related issues is also discussed. The process of learning by demonstration as well as the instructive systems is reviewed, focussing mainly on programming through visual guidance and imitation, voice commands and haptic interaction. The aspect of physical HRI as well as the safety related issues are also discussed. Additionally, a survey on multimodal communication frameworks is presented. Challenges encountered and directions for future research are discussed.

European Vegetation Archive (EVA): an integrated database of European vegetation plots

Abstract: The European Vegetation Archive (EVA) is a centralized database of European vegetation plots developed by the IAVS Working Group European Vegetation Survey. It has been in development since 2012 and first made available for use in research projects in 2014. It stores copies of national and regional vegetation- plot databases on a single software platform. Data storage in EVA does not affect on-going independent development of the contributing databases, which remain the property of the data contributors. EVA uses a prototype of the database management software TURBOVEG 3 developed for joint management of multiple databases that use different species lists. This is facilitated by the SynBioSys Taxon Database, a system of taxon names and concepts used in the individual European databases and their corresponding names on a unified list of European flora. TURBOVEG 3 also includes procedures for handling data requests, selections and provisions according to the approved EVA Data Property and Governance Rules. By 30 June 2015, 61 databases from all European regions have joined EVA, contributing in total 1 027 376 vegetation plots, 82% of them with geographic coordinates, from 57 countries. EVA provides a unique data source for large-scale analyses of European vegetation diversity both for fundamental research and nature conservation applications. Updated information on EVA is available online at http://euroveg.org/eva-database.

Vascular plants of Greece: An annotated checklist. Supplement

Abstract: Supplementary information on taxonomy, nomenclature, distribution within Greece, total range, life form and ecological traits of vascular plants known to occur in Greece is presented and the revised data are quantitatively analysed Floristic discrepancies between Vascular plants of Greece: An annotated checklist (Dimopoulos & al 2013) and relevant influential datasets (Flora europaea, Med-Checklist, Euro Med PlantBase, etc) are explained and clarified An additional quantity of synonyms and misapplied names used in previous Greek floristic literature is presented Taxonomic and floristic novelties published after 31 October 2013 are not consideredCitation: Dimopoulos P, Raus Th, Bergmeier E, Constantinidis Th, Iatrou G, Kokkini S, Strid A & Tzanoudakis D 2016: Vascular plants of Greece: An annotated checklist Supplement — Willdenowia 46: 301–347 doi: http//dxdoiorg/103372/wi4646303Version of record first published online on 26 October 2016 ahead of inclusion in December 2016 issue

Development of nickel based catalysts for the transformation of natural triglycerides and related compounds into green diesel: a critical review

Abstract: The accumulation of greenhouse gases in the atmosphere resulting from the extensive use of fossil fuels and the depletion of oil reserves due to the increasing demands for energy compel the progressive replacement of fossil fuels by renewable energy sources among which biomass. Triglycerides-based biomass such as plant oils, animal fats, waste cooking and micro-algal oils should be upgraded by transesterification, cracking/hydrocracking and selective deoxygenation (SDO) to provide, respectively, biodiesel (fatty acid methyl esters), the so-called organic liquid product (mixture of hydrocarbons in the range of gasoline, kerosene and diesel) and green diesel (hydrocarbons in the diesel range). Problems related to the production, storage and use of the already produced biodiesel shifts the research to the second and third upgrading route. Intensive work in the last ten years has shown that the noble metals (mainly palladium) and the NiMo, CoMo and NiW sulphide catalysts supported on high surface area carriers, are promising concerning SDO for producing green diesel in the context of a stand-alone process of natural triglycerides. However, the high cost of the noble metal catalysts and the eventual S-contamination of the end product when using the aforementioned sulfided catalysts have rise intensive parallel research in the last three years for developing low cost Ni-based non-sulphide catalysts. The research effort in this area seems to focus on the following issues: (i) effect of supports, nickel loading and promoters on the catalytic performance of Ni-based non-sulphide catalysts, (ii) SDO pathways over these catalysts, (iii) effect of preparation method on their catalytic performance, (iv) comparison of nickel catalysts with other metallic and sulphide catalysts, (v) development of nickel phosphide catalysts, (vi) development of NiMo, CoMo or NiW non-sulphide catalysts (reduced, carbides, nitrides) and (vii) deoxygenation in low or no hydrogen containing atmosphere. In the present article we critically review the contributions relevant to each one of the aforementioned subjects for obtaining a synthetic picture concerning the progress pointed out so far and the future perspectives as well.

The degradation potential of PET bottles in the marine environment: An ATR-FTIR based approach

Abstract: The dominance and persistence of plastic debris in the marine environment are well documented. No information exists in respect to their lifespan in the marine environment. Nevertheless, the degradation potential of plastic litter items remains a critical issue for marine litter research. In the present study, polyethylene terephthalate bottles (PETs) collected from the submarine environment were characterized using ATR-FTIR in respect to their degradation potential attributed to environmental conditions. A temporal indication was used as indicative to the years of presence of the PETs in the environment as debris. PETs seem to remain robust for approximately fifteen years. Afterwards, a significant decrease of the native functional groups was recorded; some even disappear; or new-not typical for PETs-are created. At a later stage, using the PET time series collected from the Saronikos Gulf (Aegean Sea–E. Mediterranean), it was possible to date bottles that were collected from the bottom of the Ionian Sea (W. Greece). It is the first time that such a study has been conducted with samples that were actually degraded in the marine environment.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

Abstract: [This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Online Stability in Human-Robot Cooperation with Admittance Control

Abstract: In the design of a compliant admittance controller for physical human-robot interaction, it is necessary to ensure stable and effective cooperation. The stability of the admittance controller is mainly threatened by a stiff environment. Many methods that guarantee stability in arbitrary environments, impose conservative control gains that limit the effectiveness of the cooperation. Inspired by previous work in frequency domain stability observers, a method is proposed in this paper to detect unstable behavior and stabilize the robot with online adaptation of the admittance control gains. The introduced instability index is based on frequency domain analysis, which very quickly detects unstable behavior by monitoring high frequency oscillation in the force signal. To treat the instability, an adaptation scheme of the admittance parameters is proposed, that relaxes conservative gains and improves the cooperation by considering the effect of variable admittance on the operators’ effort. We investigate two human-robot co-manipulation tasks; cooperation within a zero stiffness environment and cooperation in contact with a stiff double-wall virtual environment. The proposed methods are validated experimentally with a number of subjects in cooperation with an LWR manipulator.

Decreasing fires in Mediterranean Europe

Abstract: Forest fires are a serious environmental hazard in southern Europe. Quantitative assessment of recent trends in fire statistics is important for assessing the possible shifts induced by climate and other environmental/socioeconomic changes in this area. Here we analyse recent fire trends in Portugal, Spain, southern France, Italy and Greece, building on a homogenized fire database integrating official fire statistics provided by several national/EU agencies. During the period 1985-2011, the total annual burned area (BA) displayed a general decreasing trend, with the exception of Portugal, where a heterogeneous signal was found. Considering all countries globally, we found that BA decreased by about 3020 km2 over the 27-year-long study period (i.e. about -66% of the mean historical value). These results are consistent with those obtained on longer time scales when data were available, also yielding predominantly negative trends in Spain and France (1974-2011) and a mixed trend in Portugal (1980-2011). Similar overall results were found for the annual number of fires (NF), which globally decreased by about 12600 in the study period (about -59%), except for Spain where, excluding the provinces along the Mediterranean coast, an upward trend was found for the longer period. We argue that the negative trends can be explained, at least in part, by an increased effort in fire management and prevention after the big fires of the 1980's, while positive trends may be related to recent socioeconomic transformations leading to more hazardous landscape configurations, as well as to the observed warming of recent decades. We stress the importance of fire data homogenization prior to analysis, in order to alleviate spurious effects associated with non-stationarities in the data due to temporal variations in fire detection efforts.

Dairy and non-dairy probiotic beverages

Abstract: Nowadays there has been an increased interest in the development of new functional foods and their incorporation in a healthy diet. Such products and especially probiotics exert a beneficial effect on host gut microbiota after consumption and may be capable to prevent several diseases. Fermented beverages are traditional products that act as vehicles of probiotics in human diet. Many studies the last decades have concluded that the best substrates for the delivery of probiotics are dairy products. However lactose intolerance, high fat and cholesterol, milk allergies and also the growing trend of vegetarianism has promoted the research in the field of non-dairy probiotic products. Therefore this review highlights the recent advances in the field of probiotic beverages both from dairy and non-dairy origin.

Phylogeny and physiology of candidate phylum 'Atribacteria' (OP9/JS1) inferred from cultivation-independent genomics

Abstract: The ‘Atribacteria’ is a candidate phylum in the Bacteria recently proposed to include members of the OP9 and JS1 lineages. OP9 and JS1 are globally distributed, and in some cases abundant, in anaerobic marine sediments, geothermal environments, anaerobic digesters and reactors and petroleum reservoirs. However, the monophyly of OP9 and JS1 has been questioned and their physiology and ecology remain largely enigmatic due to a lack of cultivated representatives. Here cultivation-independent genomic approaches were used to provide a first comprehensive view of the phylogeny, conserved genomic features and metabolic potential of members of this ubiquitous candidate phylum. Previously available and heretofore unpublished OP9 and JS1 single-cell genomic data sets were used as recruitment platforms for the reconstruction of atribacterial metagenome bins from a terephthalate-degrading reactor biofilm and from the monimolimnion of meromictic Sakinaw Lake. The single-cell genomes and metagenome bins together comprise six species- to genus-level groups that represent most major lineages within OP9 and JS1. Phylogenomic analyses of these combined data sets confirmed the monophyly of the ‘Atribacteria’ inclusive of OP9 and JS1. Additional conserved features within the ‘Atribacteria’ were identified, including a gene cluster encoding putative bacterial microcompartments that may be involved in aldehyde and sugar metabolism, energy conservation and carbon storage. Comparative analysis of the metabolic potential inferred from these data sets revealed that members of the ‘Atribacteria’ are likely to be heterotrophic anaerobes that lack respiratory capacity, with some lineages predicted to specialize in either primary fermentation of carbohydrates or secondary fermentation of organic acids, such as propionate.

Ubiquity of organic nitrates from nighttime chemistry in the European submicron aerosol

Abstract: In the atmosphere nighttime removal of volatile organic compounds is initiated to a large extent by reaction with the nitrate radical (NO3) forming organic nitrates which partition between gas and particulate phase. Here we show based on particle phase measurements performed at a suburban site in the Netherlands that organic nitrates contribute substantially to particulate nitrate and organic mass. Comparisons with a chemistry transport model indicate that most of the measured particulate organic nitrates are formed by NO3 oxidation. Using aerosol composition data from three intensive observation periods at numerous measurement sites across Europe, we conclude that organic nitrates are a considerable fraction of fine particulate matter (PM1) at the continental scale. Organic nitrates represent 34% to 44% of measured submicron aerosol nitrate and are found at all urban and rural sites, implying a substantial potential of PM reduction by NOx emission control.

Work Function Tuning of Reduced Graphene Oxide Thin Films

Abstract: Graphene oxide (GO) has shown great potential as a component in various devices due to its excellent solution processability and two-dimensional structure. However, the oxygenated form of graphene has a moderate charge-transport capability. The latter parameter may be enhanced through controlled deoxygenation of GO with subsequent tuning of its work function (WF). Various reduction approaches were employed to investigate the effect of the oxygen content on the work function of GO derivatives as thin films on an indium tin oxide substrate. Such films were reduced by stepwise thermal annealing in ultrahigh vacuum up to 650 °C, by chemical reduction with hydrazine, or by a combination of chemical and thermal reduction processes. The effect of the GO film thickness and the flake size on the WF was also investigated. UV photoelectron spectroscopy and X-ray photoelectron spectroscopy were used to correlate the WF of GO derivatives with their oxygen content. The results showed that the WF is strongly dependent o...

Electronic cigarette use in the European Union: analysis of a representative sample of 27 460 Europeans from 28 countries.

Abstract: Aims To assess prevalence of electronic cigarette (e-cigarette) use, reported changes in smoking status due to e-cigarette use and correlates of e-cigarette use in the European Union (EU) member states in 2014. Design Cross-sectional survey of EU citizens representative of the population (Special Eurobarometer 429). Setting All 28 Member States of the EU. Participants A total of 27 460 EU citizens aged ≥ 15 years (after excluding those who responded ‘Do not know’ to the questions about smoking status and e-cigarette use). Measurements Descriptive analysis [%, 95% confidence interval (CI)] of e-cigarette use prevalence (current use, past use and past experimentation) according to smoking status, self-reported changes in smoking status according to patterns of e-cigarette use and logistic regression analysis to examine correlates of e-cigarette use, especially socio-demographic factors and smoking status. Findings Ever e-cigarette use was reported by 31.1% (95% CI = 30.0–32.2%) of current smokers, 10.8% (95% CI = 10.0–11.7%) of former smokers and 2.3% (95% CI = 2.1–2.6%) of never smokers. Past experimentation [7.2% (95% CI = 6.9–7.5%)] was more common than current [1.8% (95% CI = 1.6–1.9%)] and past use [2.6% (95% CI = 2.4–2.8%)]. Extrapolated to the whole population, approximately 48.5 million EU citizens were ever e-cigarette users, with 76.8% using nicotine-containing e-cigarettes. An estimated 6.1 and 9.2 million EU citizens had quit and reduced smoking with the help of e-cigarettes, respectively. Initiation with e-cigarettes was reported by 0.8% (95% CI = 0.6–0.9%) of participants who reported ever use of any tobacco-related product. Only 1.3% (95% CI = 1.1–1.5%) of never smokers used nicotine-containing e-cigarettes, with 0.09% (95% CI = 0.04–0.14%) reporting daily nicotine use. Smoking cessation with the help of e-cigarettes was reported by 35.1% (95% CI = 30.7–39.5%) of current e-cigarette users, while a further 32.2% (95% CI = 29.9–36.5%) reported smoking reduction. Being current [odds ratio (OR) = 21.23, 95% CI = 18.32–24.59) or former smokers (OR = 6.49, 95% CI = 5.49–7.67) were the strongest correlates of ever e-cigarette use. Conclusions E-cigarette use in the European Union appears to be largely confined to current or former smokers, while current use and nicotine use by people who have never smoked is rare. More than one-third of current e-cigarette users polled reported smoking cessation and reduction.