Structural feature based computational approach of toxicity prediction of ionic liquids: Cationic and anionic effects on ionic liquids toxicity

yesThe density functional theory (DFT) based a unique model has been developed to predict the toxicity of ionic liquids using structural-feature based quantum chemical reactivity descriptors. Electrophilic indices (ω), the energy of highest occupied (EHOMO) and lowest unoccupied molecular orbital, (ELUMO) and energy gap (∆ E) were selected as the best toxicity descriptors of ILs via Pearson correlation and multiple linear regression analyses. The principle components analysis (PCA) demonstrated the distribution and inter-relation of descriptors of the model. A multiple linear regression (MLR) analysis on selected descriptors derived the model equation for toxicity prediction of ionic liquids. The model predicted toxicity values and mechanism are very consistent with observed toxicity. Cationic and side chains length effect are pronounced to the toxicity of ILs. The model will provide an economic screening method to predict the toxicity of a wide range of ionic liquids and their toxicity mechanism

Effects of Burkholderia thailandensis rhamnolipids on the unicellular algae Dunaliella tertiolecta

The effects of rhamnolipids (RLs) produced and further purified from Burkholderia thailandensis, on the unicellular microalgae Dunaliella tertiolecta were investigated, in terms of RLs ability to affect algal growth, photosynthetic apparatus structure and energy flux, round and through photosystems II and I. Specifically, 24–48 h RLs-treated algae (RLs at concentrations ranged from 5 to 50 mg L−1) showed significantly decreased levels of growth rate, while increased levels of Chl a and b were obtained only in 72–96 h RLs-treated algae. Similarly, although no changes were obtained in the Chl a/b ratio and almost all chlorophyll fluorescence parameters over time, yields of electron transport (ϕR0, ϕE0) and respective performance index (PItotal) were negatively affected at 72 and 96 h. Based on those findings, it seems that the inhibitory effect of RLs on the algae growth rate after 24 and 48 h and the gradual attenuation of the phenomenon (after 72 h of exposure), may indicate the initial response of the organism, as well as algae ability to overcome, since RLs showed no effects on algae photosynthetic ability. Those findings reveal for the first time that RLs from Burkholderia thailandensis are not harmful for Dunaliella tertiolecta. However, further studies with the use of more aquatic species could be essential for assessing the RLs-mediated effects on aquatic biota

Thermochemical Conversion of Lipid-extracted Algal Biomass to Value-Added Sustainable Products

The extensive use of fossil fuels has increased the CO2 emissions, a phenomenon that has increased the demand for renewable energy and resources. Algae, photosynthetic aquatic organisms, have recently caught attention due to their high growth rate and the high CO2 capture ability. Biofuels and bioproducts from algae are considered promising alternatives because of their lower carbon footprint. Lipids are by far the most popular algal product, as they find applications in both fuels, such as biodiesel, and products, such as nutraceuticals and cosmetics. However, after lipid extraction, conversion of the residual algal biomass to value-added products is viewed as essential for strengthening and diversifying the economics of algae biorefineries. Hence, the overall objective of this research is to develop sustainable algal products, such as hydrochar and activated char, from lipid-extracted algal biomass to replace fossil-derived materials, such as charcoal and activated carbon. In the first phase, mechanical, thermochemical, and electromagnetic cell disruption methods were tested to maximize lipid extraction from wet biomass of Picochlorum oculatum, an industrially promising marine alga. Among mechanical methods, grinding with and without liquid nitrogen was employed, while among thermochemical methods sulfuric and nitric acid were tested. As for electromagnetic methods, ultrasonication was performed using an ultrasound bath. After cell disruption, two different solvent systems were tested for lipid extraction, namely chloroform and methanol (2:1) and hexane and isopropanol (3:2). Among the cell disruption methods, grinding with liquid nitrogen was the most effective method with a 14.8% lipid yield (content) without affecting the lipid composition that is important for biodiesel production. Following lipid extraction, lipid-extracted algae (LEA) was obtained and thermochemically converted into hydrochar through a promising method named hydrothermal carbonization (HTC), which represents the second phase of this project. The effect of temperature, reaction time, and solids loading on hydrochar yield were investigated. Response surface methodology was applied to study the effects of temperature (180-220°C), reaction time (1-3 h), and solids loading (8-15%). The optimum hydrochar yield was ~37% and was obtained at 180 oC after a reaction time of 3 h at a solids loading of 15%. The solid product, algal hydrochar, is a material rich in oxygen functional groups and carbon (up to 67.3%) and hence a promising candidate for remediation of wastewaters. In addition to hydrochar, hydrothermal carbonization also generates an aqueous phase rich in nitrogen and other elements that need to be treated before discharge into water bodies. The aqueous phase was found to contain high concentrations of nitrogen (2.4 g/L), phosphorus (1.75 g/L), organic carbon (20.9 g/L), and trace elements, which are useful nutrients for algae. Utilization of the aqueous phase in algae cultivation can potentially reduce algae production cost, while mitigating waste generation. Hence, in the third phase of this study, the potential of the generated aqueous phase to serve as a source of nutrients for lipid production from Chlorella vulgaris was assessed. The fourth phase of the project examined chemical activation of algal hydrochar with potassium hydroxide (KOH) to produce value-added activated char by increasing its surface area and pore size. A systematic approach was employed to study the effects of different activation factors such as temperature, impregnation ratio (mass ratios of KOH and hydrochar), and activation time on the characteristics of activated char. Temperatures of 400-600 0C, ratios of 0.25- 1.0, and activation times of 30-60 min were employed. The maximum Brunauer-Emmett-Teller (BET) surface area of 847 m2/g was achieved at 600 oC after 30 min at a ratio of 1:1. Finally, in the fifth phase of the project, a techno-economic analysis (TEA) of the integrated carbonization/activation process was carried out to assess the economic viability of the process and its potential for commercial development. Using Aspen Plus simulation to analyze process economics, the minimum selling price of activated char was determined to be $2,300/ton. Overall, the development of hydrochar and activated char from lipid- extracted algae paves a path towards a more cost-competitive and sustainable algae biorefinery. Recommended next steps include testing of catalysts to enhance the HTC process and assessment of the efficacy of hydrochar and activated char in carbon capture applications and removal of organic pollutants, such as siloxanes, from landfill gas

Investigation of ionic liquids toxicity with the use of bio-indicators and in vitro biological models

Given that the application of ionic liquids (ILs), either pure or in mixtures (IL-IL, IL-water, IL-acetone), is increasing rapidly, the present study investigates the toxic effects of the widely used imidazolium-based ILs, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF4]), on a battery of aquatic organisms, as well as whether acetone could mediate ILs toxicity. In this context, the algae Dunaliella tertiolecta and Scenedesmus rubescens, crustaceans Thamnocephalus platyurus and Artemia franciscana, rotifers Brachionus calyciflorus and Brachionus plicatilis and the bivalve mollusk Mytilus galloprovincialis were exposed to different concentrations of [bmim][BF4], [omim][BF4] and/or a binary mixture of [bmim][BF4]–[omim][BF4] (1:1), with or without 0.06% v/v acetone, in order to determine the half maximal inhibitory concentration (IC50 values) or the median lethal concentration (LC50 values), in each case. Subsequently, mussels were exposed to sub- and nonlethal concentrations of each IL (with or without the presence of acetone) for investigating the IL-mediated cytotoxic (currently tested with the use of neutral red retention time/NRRT assay), oxidative (superoxide anions and lipid peroxidation enhancement) and genotoxic (with the use of Comet and MN assays) effects in different tissues (hemolymph/hemocytes and gills). In addition, the cytokinesis-block micronucleus assay (CBMN) was applied in human lymphocytes, as a sensitive assay for assessing the genotoxic and mutagenic ability of both ILs, with or without the presence of acetone. Moreover, in order to investigate the role of abiotic factors, such as salinity, to the induced toxic effects, the physiological behavior of the green algae D. tertiolecta (in terms of growth rate, carotene and chlorophyll a content) when exposed to ILs under different salinities (30 and 35‰) was also investigated. Except from the description of the toxic profile of the studied ILs, a more mechanistic approach, concerning ILs-mediated toxic mode of action, as well as the modulatory role of acetone on ILs-mediated toxic behavior was further performed, using isolated [omim][BF4]-treated mussel hemocytes, primarily incubated with the chaotropic agent guanidine hydrochloride (1mM GndHCl) and LC-MS-TOF analysis, respectively. According to the present study, [bmim][BF4] and [omim][BF4] could induce not only lethal effects on challenged species but also cytotoxic, oxidative, neurotoxic and genotoxic effects, as revealed by stress indices values, currently observed in tissues of M. galloprovincialis and in human lymphocytes. [omim][BF4] was found to be more toxic than [bmim][BF4] in all cases, while its toxicity seemed to be significantly modulated by the presence of acetone. ILs-mediated toxic mode of action seemed to rely on their ability to disrupt membrane proteins and lipid membrane bilayer integrity and function, as revealed using GndHCl pre-treated hemocytes, while the results of the LC-MS-TOF analysis showed that acetone probably alters [omim][BF4] hydrophilic/lipophilic character and viscosity, which in turn mediates its cellular interaction, membrane permeability and its concomitant adverse effects. Moreover, other factors, such as the physicochemical parameters and the composition of the environment/nutrient are also very important, as they can affect cells’ ability to respond under various conditions, especially when being under stress. In particular, salinity levels could play a key role in ILs-mediated inhibitory effects on D. tertiolecta, thus acting against algal growth rate rather than Chl a synthesis, merely due to the existence of a cross-linking with carotenoids. In conclusion, the present study indicates that the characterization of the imidazolium-based ILs as “green” should not be generalized and shows for the first time that carrier solvents, such as acetone, could be used for the development and usage/application of more environmentally safe ILs.Σκοπός της παρούσας μελέτης ήταν η εκτίμηση του περιβαλλοντικού κινδύνου από τα ευρέως χρησιμοποιούμενα ιμιδαζολικά ιοντικά υγρά (ILs), τετραφθοροβορικό 1-βούτυλο-3-μεθυλιμιδαζόλιο (1-butyl-3-methylimidazolium tetrafluoroborate /([bmim][BF4]) και τετραφθοροβορικό 1-μέθυλο-3-οκτυλιμιδαζόλιο (1-octyl-3-methylimidazolium tetrafluoroborate /[omim][BF4]), με την χρήση οργανισμών βιο-ενδεικτών και in vitro βιολογικών μοντέλων. Παράλληλα, καθώς η πιθανότητα χρήσης διαλυμάτων ILs-οργανικού διαλύτη σε ένα πλήθος εφαρμογών είναι αυξημένη, μελετήθηκε η επίδραση της ακετόνης στην ικανότητα των ILs να επάγουν φαινόμενα τοξικότητας. Αναλυτικότερα, πραγματοποιήθηκαν δοκιμές τοξικότητας με την χρήση των φυτοπλαγκτονικών ειδών Dunaliella tertiolecta και Scenedesmus rubescens, των καρκινοειδών Thamnocephalus platyurus και Artemia franciscana, των τροχοζώων Brachionus calyciflorus και Brachionus plicatilis, του δίθυρου μαλακίου Mytilus galloprovincialis, παρουσία ή απουσία ακετόνης (0.06% v/v). Πέραν της ικανότητάς τους να προκαλούν θνησιμότητα στους εκτιθέμενους οργανισμούς, διερευνήθηκε η πιθανότητα επαγωγής κυτταροτοξικών (τεχνική Neutral Red Retention Time), νευροτοξικών (ενζυμική δραστικότητα ακετυλ-χολινεστεράσης/AChE) και γενοτοξικών (συχνότητα εμφάνισης μικροπυρήνων/MN, τεχνική ανάλυσης κομητών/MS assay) επιπτώσεων, καθώς και φαινομένων οξειδωτικής καταπόνησης (προσδιορισμός επιπέδων σουπεροξειδικών ανιόντων, προσδιορισμός επιπέδων μηλονικής διαλδεϋδης/ MDA) σε ιστούς (αιμόλεμφος/αιμοκύτταρα και βράγχια) του είδους M. galloprovincialis. Επιπλέον, μελετήθηκε η κυτταροτοξική και μεταλλαξιγόνος δράση των ILs, εφαρμόζοντας την τεχνική των μικροπυρήνων με τη χρήση της κυτταροχαλασίνης-Β (CBMN), σε καλλιέργειες ανθρώπινων λεμφοκυττάρων. Παράλληλα, για να μελετηθεί καλύτερα ο μηχανισμός δράσης των ILs και η αλληλεπίδρασή τους με την ακετόνη πραγματοποιήθηκε ανάλυση LC-MS-TOF, και in vitro μελέτες σε απομονωμένα αιμοκύτταρα του μυδιού M. galloprovincialis, έπειτα από επώαση τους με τον χαοτροπικό παράγοντα υδροχλωρική γουανιδίνη (1 mM). Τέλος, προκειμένου να διερευνηθεί η επίδραση των φυσικοχημικών παραμέτρων, όπως η αλατότητα, στην φυσιολογική απόκριση των φυτοπλαγκτονικών οργανισμών (ρυθμός αύξησης, επίπεδα χλωροφύλλης α και ολικών καροτενοειδών), πραγματοποιήθηκε έκθεση καλλιεργειών D. tertiolecta στα ILs υπό διαφορετικές αλατότητες (30 και 35‰). Σύμφωνα με τα αποτελέσματα, τα ILs μειώνουν σημαντικά τη βιωσιμότητα των εκτιθέμενων οργανισμών και προκαλούν σημαντικές προ-παθολογικές καταστάσεις. Ειδικότερα, το [οmim][BF4] που φέρει μεγαλύτερη αλκυλική αλυσίδα, εμφανίζει μεγαλύτερη τοξικότητα, σε σχέση με το [bmim][BF4] και το μίγμα [bmim][BF4]-[οmim][BF4], προκαλώντας σημαντικές διαταραχές στη φυσιολογία των εκτιθέμενων ατόμων/κυττάρων, πιθανό λόγω της ικανότητας του IL να αλληλεπιδρά με τα φωσφολιπίδια και τις πρωτεΐνες των κυτταρικών μεμβρανών, ενεργοποιώντας μια σειρά αλυσιδωτών αντιδράσεων στο εσωτερικό των κυττάρων. Το είδος και η έκταση των επαγόμενων φαινομένων επηρεάζεται σημαντικά από την παρουσία της ακετόνης, η οποία αναστέλλει σε σημαντικό βαθμό τις τοξικές επιπτώσεις του [omim][BF4]. Σύμφωνα με την ανάλυση LC-MS-TOF, φαίνεται πως η ακετόνη μεταβάλλει το ιξώδες και την λιποφιλικότητα των ILs και κατ’ επέκταση την ικανότητά τους να αλληλεπιδρούν με τις βιολογικές μεμβράνες. Τέλος, η τοξικότητα των ILs φαίνεται πως εξαρτάται σε μεγάλο βαθμό από τις φυσικοχημικές παραμέτρους του περιβάλλοντος, καθώς επηρεάζουν την ικανότητα των κυττάρων να ανταπεξέρχονται σε διαφορετικές συνθήκες stress. Συγκεκριμένα, η αλατότητα φάνηκε να παίζει σημαντικό ρόλο στο ρυθμό αύξησης του μικροφύκους D. tertiolecta. Συμπερασματικά, τα αποτελέσματα της παρούσας μελέτης αμφισβητούν την ορθότητα του χαρακτηρισμού των ιμιδαζολικών ILs ως «Πράσινοι» διαλύτες. Παράλληλα, αναδεικνύει για πρώτη φορά το σημαντικό ρόλο της ακετόνης στη ρύθμιση του τοξικού χαρακτήρα των ILs, συμβάλλοντας με αυτό τον τρόπο στην προσπάθεια παραγωγής, ανάπτυξης και χρήσης περισσότερο περιβαλλοντικά φιλικών ILs

Μελέτη του επιδημιολογικού προφίλ της φυματίωσης στους μετανάστες στην Ελλάδα

Η φυματίωση, μία σοβαρή λοιμώδης νόσος και μία από τις κυριότερες αιτίες θανάτου παγκοσμίως, αποτελεί σημαντικό πρόβλημα Δημόσιας Υγείας ακόμη και σήμερα. Τα τελευταία χρόνια έχει καταγραφεί μία πτώση στην επίπτωση της φυματίωσης στις περισσότερες χώρες της Ευρωπαϊκής Ένωσης. Αυτή η πτωτική πορεία όμως έχει μειωθεί από την αναζωπύρωση της νόσου στις ευάλωτες πληθυσμιακές ομάδες όπως είναι οι μετανάστες από χώρες με υψηλό επιπολασμό και με ελλιπείς στρατηγικές πρόληψης και ελέγχου της νόσου. Επιπλέον η ανθεκτική φυματίωση είναι πιο συχνή στους αλλοδαπούς παρά στους Ευρωπαίους πολίτες. Σκοπός της παρούσας εργασίας είναι η μελέτη και διερεύνηση της επιδημιολογικής εικόνας της φυματίωσης στους μετανάστες στην Ελλάδα. Συγκεντρώθηκαν και αναλύθηκαν οι πληροφορίες των δελτίων δήλωσης της περιόδου 2007-2008 και 2017-2018 από τα αρχεία του Εθνικού Κέντρου Αναφοράς Μυκοβακτηριδίων ώστε να προκύψουν συμπεράσματα σχετικά με το επιδημιολογικό προφίλ της φυματίωσης στους μετανάστες και πώς αυτό έχει μεταβληθεί τα τελευταία χρόνια στην Ελλάδα.Tuberculosis, a serious infectious disease and one of the leading causes of death worldwide, remains a major public health problem. Tuberculosis incidence rates have fallen in most European Union countries over the past years. This declining trend however has been slowed down by the resurgence of the disease in vulnerable population groups such as migrants coming from high tuberculosis incidence countries with inefficient and of low quality health care services. Moreover drug-resistant tuberculosis is more common in foreign-born persons than European citizens. The aim of this study is to investigate the epidemiology of tuberculosis among migrants in Greece. Data were collected from the National Reference Laboratory for Mycobacteria records for the periods 2007-2008 and 2017- 2018. Information in the mandatory notification reports was reviewed and analyzed in order to determine if the epidemiological characteristics of tuberculosis among migrants in Greece have changed over the recent year