Malijevsky A.,ICT Prague |
Malijevsky A.,Czech Institute of Chemical Process Fundamentals |
Parry A.O.,Imperial College London
Journal of Physics Condensed Matter | Year: 2014
We study the order of capillary condensation and evaporation transitions of a simple fluid adsorbed in a deep capillary groove using a fundamental measure density functional theory (DFT). The walls of the capillary interact with the fluid particles via long-ranged, dispersion, forces while the fluid-fluid interaction is modelled as a truncated Lennard-Jones-like potential. We find that below the wetting temperature Tw condensation is first-order and evaporation is continuous with the metastability of the condensation being well described by the complementary Kelvin equation. In contrast above Tw both phase transitions are continuous and their critical singularities are determined. In addition we show that for the evaporation transition above T w there is an elegant mapping, or covariance, with the complete wetting transition occurring at a planar wall. Our numerical DFT studies are complemented by analytical slab model calculations which explain how the asymmetry between condensation and evaporation arises out of the combination of long-ranged forces and substrate geometry. © 2014 IOP Publishing Ltd.
Taubner T.,ICT Prague |
Copikova J.,ICT Prague |
Havelka P.,VUOS a.s. |
Synytsya A.,ICT Prague
Cellulose | Year: 2013
Amidated derivatives of monocarboxy cellulose (MCC), the product of cellulose oxidation, containing carboxyl groups only at C-6 position, were prepared and characterised. Two-step way of amidation was based on the esterification of C-6 carboxyls in MCC by reaction with methanol at 60 °C for 72 h and further amino-de-alkoxylation (aminolysis) of the obtained methyl ester with n-alkylamines, hydrazine and hydroxylamine in the N,N-dimethylformamide medium. Purity and substitution degree of the products were monitored by vibration spectroscopic methods (FTIR and FT Raman) and organic elemental analysis. Analytical methods confirmed the preparation of highly or moderately substituted N-alkylamides, hydrazide and hydroxamic acid of MCC. © 2013 Springer Science+Business Media Dordrecht.
Capdevielle A.,IRSTEA |
Capdevielle A.,European University of Brittany |
Sykorova E.,ICT Prague |
Biscans B.,CNRS Chemical Engineering Laboratory |
And 2 more authors.
Journal of Hazardous Materials | Year: 2013
A sustainable way to recover phosphorus (P) in swine wastewater involves a preliminary step of P dissolution followed by the separation of particulate organic matter. The next two steps are firstly the precipitation of struvite crystals done by adding a crystallization reagent (magnesia) and secondly the filtration of the crystals. A design of experiments with five process parameters was set up to optimize the size of the struvite crystals in a synthetic swine wastewater. More than 90% of P was recovered as large crystals of struvite in optimal conditions which were: low Mg:Ca ratio (2.25:1), the leading parameter, high N:P ratio (3:1), moderate stirring rate (between 45 and 90. rpm) and low temperature (below 20 °C).These results were obtained despite the presence of a large amount of calcium and using a cheap reactant (MgO). The composition of the precipitates was identified by Raman analysis and solid dissolution. Results showed that amorphous calcium phosphate (ACP) co-precipitated with struvite and that carbonates were incorporated with solid fractions. © 2012 Elsevier B.V.
Koci V.,ICT Prague |
Mocova K.,ICT Prague |
Kulovana M.,T. G. Masaryk Water Research Institute |
Vosahlova S.,ENVISAN GEM
Environmental Science and Pollution Research | Year: 2010
Background, aim, and scope: The purpose of this study was to compare the suitability of different phytotoxicity testing procedures for the evaluation of toxicity associated with both soil contamination and solid wastes, both of which can be of environmental risk to plants. Ten different representative types of contaminated soils and solid waste samples were chosen from the Czech Republic. Materials and methods: Both solid-phase and aquatic toxicity testing procedures on mono- and dicotyledonous plants were performed using Lactuca sativa L., Sinapis alba L., Hordeum vulgare L., Triticum aestivum L., Lemna minor L., and the chlorococcal algae Desmodesmus subspicatus (syn. Scenedesmus subspicatus), strain Brinkmann 1953/SAG 86.81. An innovative classification scheme, using the intensity of toxic effects upon the plants, is presented in the study. Detailed chemical characterizations of both solid samples and their aquatic elutriates were carried out, using the appropriate ISO guidelines. In the solid samples, all the congeners of polychlorinated biphenyls were analyzed, together with 16 U. S. EPA polyaromatic hydrocarbons, the aggregate of C10-C40 hydrocarbons, total organic carbon, extractable organic halogens, as well as the majority of the environmentally toxic metals. In the aquatic elutriates, parameters analyzed were pH, conductivity, dissolved organic content, phenol index, main anions, and the majority of the environmentally relevant metals. Results: Eight out of ten samples tested expressed phytotoxic properties on tested organisms. Only three of the samples were toxic to both aquatic and terrestrial organisms in the tests. This demonstrates how different substances present in different samples can express different types of toxic effects, resulting in the illogical substituting terrestrial bioassays with aquatic ones. Discussion: Based upon our experience, we propose the following battery of bioassays for use in the characterization of toxic properties of solid wastes and contaminated soils: Aquatic ecosystems were tested by the algae D. subspicatus and plant L. minor; and the terrestrial ecosystems were tested by the dicotyledonous L. sativa and monocotyledonous H. vulgare. This proposed new battery of bioassays for the detection of phytotoxicity of both solid wastes and contaminated soils has higher sensitivity (as well as greater ecological relevance) compared to the battery of bioassays currently used in the Czech Republic. Conclusions: The tests currently used for regulatory purposes in the Czech Republic are phytotoxicity tests of elutriates, using S. alba and D. subspicatus, which have been found insufficiently sensitive to the range of different pollutants present in contaminated soils and/or solid wastes. If only aquatic bioassays are used for the toxicity testing, it is possible that the toxic effects of substances (poorly or totally) insoluble in water might be underestimated. The new proposed system of toxicity classification has proven to be both practical and sensitive. Recommendations and perspectives: This recommended alternative battery of phytotoxicity tests includes both aquatic tests of waste elutriates (with the algae D. subspicatus along with the aquatic plant L. minor), in addition to tests of the terrestrial solid samples (with the dicotyledonous L. sativa and the monocotyledonous H. vulgare). This battery of bioassays is sufficiently sensitive, representing a majority of types of aquatic and terrestrial plants. © Springer-Verlag 2009.
Geun Goo B.,Catholic University of Korea |
Baek G.,Catholic University of Korea |
Jin Choi D.,ICT Prague |
Il Park Y.,ICT Prague |
And 5 more authors.
Bioresource Technology | Year: 2013
Extracellular polysaccharide (EPS) was isolated from defatted micro-algae Dunaliela tertiolecta and defined as linear (1 → 4)-α-d-glucan based on monosaccharide composition, enzymatic and spectroscopic analyses. Optimization and characterization of acidic and enzymatic hydrolyses of EPS have been performed for its potential use as a renewable biorefinery material. The hydrolytic methods were improved to assess the effect of substrate specificity, reaction time, pH, ionic strength and temperature on efficiency of glucose production. EPS was effectively converted into glucose within one-step enzymatic or acidic hydrolysis under optimized conditions. Over 90% recovery of glucose was achieved for both hydrolytic approaches. High potential production of EPS and high yield conversion of this substrate to glucose may allow further exploration of microalga D. tertiolecta as a potential biomass producer for biotechnological and industrial exploitation of bioethanol. © 2012 Elsevier Ltd.
Dzuman Z.,ICT Prague |
Vaclavikova M.,ICT Prague |
Polisenska I.,Agrotest Fyto Ltd |
Veprikova Z.,ICT Prague |
And 3 more authors.
Analytical and Bioanalytical Chemistry | Year: 2014
Enzyme-linked immunosorbent assay (ELISA) represents a bioanalytical strategy frequently used for rapid screening of mycotoxin deoxynivalenol (DON) in cereals and derived products. Due to a considerable affinity of some anti-DON antibodies to structurally similar DON metabolites, such as DON-3-glucoside (DON-3-Glc) and 3-acetyl-DON (3-ADON), a significant overestimation of DON concentrations may occur. A validation study of six commercial DON-dedicated ELISA kits, namely Ridascreen DON, Ridascreen FAST, DON, DON EIA, AgraQuant DON Assay, Veratox 5/5, and Veratox HS was carried out on wheat, barley, and malt matrices. Performance characteristics of all tested ELISAs were determined using aqueous solutions of DON, DON-3-Glc, and 3-ADON analytical standards, further with extracts of artificially spiked blank cereals, and finally with matrix-matched standards of all three compounds. In the final phase, the accuracy of data was assessed through a comparison of DON concentrations determined by particular ELISAs and reference ultra-high-performance liquid chromatography-tandem mass spectrometry method. For this purpose, both quality control materials and a comprehensive set of naturally and artificially contaminated samples of wheat, barley, and malt were analyzed. High cross-reactivities were proved for both DON-3-Glc and 3-ADON in the majority of examined assays, and moreover, a considerable contribution of some matrix components to overestimation of DON results was confirmed. © Springer-Verlag Berlin Heidelberg 2013.
Vosmanska V.,ICT Prague |
Kolarova K.,ICT Prague |
Rimpelova S.,ICT Prague |
Svorcik V.,ICT Prague
Cellulose | Year: 2014
In this paper we focused on cold plasma treatment of oxidized cellulose haemostat. Oxidized cellulose was modified in inert argon plasma. The changes of surface composition were examined by XPS and FTIR. Surface morphology of fibres was studied by SEM. Gravimetry was used to study ablation and water absorption. Antibacterial effect of pristine and plasma treated samples was examined by growth of Escherichia coli and Staphylococcus epidermidis. Behaviour of pristine and plasma treated samples in water, physiological saline solution and phosphate buffered saline was observed by changes in the pH of their solutions. Modification of oxidized cellulose by inert argon plasma caused significant changes in the chemical composition of its surface layers as well as changes in morphology of those layers while maintaining or improving the antibacterial properties. We found out that modification by inert argon plasma improves the properties necessary for haemostatic function of oxidized cellulose. © 2014 Springer Science+Business Media Dordrecht.
Firatligil-Durmus E.,ICT Prague |
Firatligil-Durmus E.,Technical University of Istanbul |
Sarka E.,ICT Prague |
Bubnik Z.,ICT Prague |
And 2 more authors.
Journal of Food Engineering | Year: 2010
Image analysis system was used to provide geometric parameters of legume seeds, which are important for designing of engineering processes such as drying, milling, germination etc. Measured features of bean and lentil seeds were projected area, equivalent diameter, MaxFeret, MinFeret and thickness. Three approximation models (an oblate spheroid, two sphere segments and a triaxial ellipsoid) were used to evaluate volume and surface area of lentil and bean seeds of various varieties. The best approximation model was found as the triaxial ellipsoid and the oblate spheroid for bean varieties and two sphere segments for lentil varieties. From the model data estimated specific surface area were ranged from 5.1-5.8 cm2/g for bean varieties and 11.57-11.95 cm2/g for lentil varieties. Image analysis system provided fast and accurate values of important technological properties of legume such as geometric parameters, volume and surface area. © 2009 Elsevier Ltd. All rights reserved.
Capek J.,ICT Prague |
Vojtech D.,ICT Prague
Key Engineering Materials | Year: 2014
Porous magnesium materials appear to be promising candidates for scaffold production. In this work we prepared porous magnesium samples by powder metallurgy using ammonium bicarbonate as space-holder particles. We focused on the influence of the magnesium powder size and shape on product characteristics. Samples prepared using magnesium chips showed significantly worse flexural properties than samples with similar porosities prepared from an equi-axed magnesium powder. Therefore, we can conclude that spherical particles are more suitable for the preparation of porous objects by powder metallurgy. © (2014) Trans Tech Publications.
Kouril M.,ICT Prague |
Novak P.,ICT Prague |
Bojko M.,ICT Prague
Cement and Concrete Research | Year: 2010
The threshold chloride concentration for stainless steels activation in concrete environments depends not only on chemical composition of the steel and on pH level of concrete pore solution but is also considerably affected by the superficial state of the steel. The presence of scales leads to significant decrease of corrosion resistance. This study evaluates the corrosion resistance of various stainless steels exposed to pore solutions of fresh concrete by means of electrochemical methods. All tested materials with bare surface, except for martensitic chromium steel FeCr12, proved to be completely resistant to fresh concrete pore solution containing chlorides. If the surface is scaled, the identically high resistance cannot be expected even for the most alloyed stainless steels. © 2009 Elsevier Ltd. All rights reserved.