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Prague, Czech Republic
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Taubner T.,Institute of Animal Science | Marounek M.,Institute of Animal Science | Synytsya A.,ICT Prague
International Journal of Biological Macromolecules | Year: 2017

Alginic acid is a suitable material for modification to prepare new derivatives because of presence of its carboxyl groups. The high content of carboxyl groups over the entire length of its chain renders it an easily modifiable material with a possibility of achieving a high degree of substitution in the prepared derivatives. The salt of alginic acid (sodium alginate) is readily commercially available and is widely used in many branches of chemistry. Alginic acid was thus selected as the substrate for amidation. The amidation used two-steps: methyl esterification followed by amino-de-alkoxylation. The aim of this study was to prepare highly substituted derivatives with different polysaccharide chain characteristics. As such, the alginic acid was modified by the two-step amidation based on the esterification of the alginic acid carboxyl groups by reaction with methanol and further amino-de-alkoxylation (aminolysis) of the obtained methyl ester with amidation reagents (n-alkylamines, hydrazine and hydroxylamine). The purity and substitution degree of the prepared derivatives were monitored by vibration spectroscopic methods (FTIR and FT Raman) and organic elemental analysis. These analytical methods confirmed the preparation of highly or moderately substituted N-alkylamides, hydrazide and hydroxamic acid of alginic acid. © 2017 Elsevier B.V.

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.

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.

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