Skalicky M.,Institute of Chemical Technology Prague |
Skalicka V.,Institute of Chemical Technology Prague |
Paterova J.,Institute of Chemical Technology Prague |
Rybackova M.,Institute of Chemical Technology Prague |
And 4 more authors.
Organometallics | Year: 2012
A series of fluorous silver complexes bearing two fluorous NHC ligands was synthesized from bis(polyfluoroalkylated) or bis(polyfluoropolyoxaalkylated) imidazolium salts and silver oxide in acetonitrile. The starting salts were prepared either under conventional conditions in two steps via polyfluoroalkylated imidazoles or preferably directly from imidazole and the respective polyfluoroalkyl triflates or polyfluoropolyoxaalkyl nonaflates bearing a nonfluorinated ethylene or methylene spacer. Surprisingly, striking differences in fluorophilicity were observed for both starting imidazolium salts and target Ag-NHC complexes depending on the type of polyfluorinated chains. While the complexes bearing a polyfluoroalkyl ponytail displayed moderate fluorophilicities f i in the range of 0.9-1.8, the presence of fluorinated polyether chains resulted in much higher fluorophilicity reaching for unbranched polyethers values as high as 3.2 with excellent solubility in perfluorinated solvents. For the explanation, DFT calculations on the model imidazolium salts showed that, in contrast to polyfluoroalkyl ponytails pointing out of the imidazolium rings, dominant conformation of the polyfluoropolyether chain is able to shield fluorophobic counteranions against the perfluorinated environment, minimizing thus fluorophobic interactions. We also employed DFT calculations for the confirmation of the higher flexibility of perfluoropolyether chains compared with perfluoroalkyl chains, scanning the energy content of two model compounds, perfluorohexane and perfluoro-3- oxahexane, on their C3-C4 or O-C3 torsion angle. © 2012 American Chemical Society.
Dumbrovsky M.,Brno University of Technology |
Sobotkova V.,Brno University of Technology |
Sarapatka B.,Palacky University |
Chlubna L.,TGM Water Research Institute
Ecological Engineering | Year: 2014
Soil erosion in the Czech Republic is a serious degradation process affecting more than 50% (about 1.5 million ha) of arable land, 80% of which is affected by water erosion. Soil degradation by water erosion and related impacts can be effectively limited by various types of soil erosion control measures. This study is a sensitivity analysis of the impact parameters of selected types of soil erosion control measures on changes in flow rate in the catchment area. The study further evaluates the effectiveness of these measures. A soil erosion control measure in the form of broad-base terrace, designed with different variants, was evaluated for this analysis in two selected case study areas in the Hostišovský stream catchment (tributary of the Dřevnice, Czech Republic). In the model locations evaluation was carried out on the influence of design variants of furrowed broad-base terraces on water-course sedimentation and on potential damage in urban areas. It was found that, in model Location L1 and variant V5, there was an 80% reduction in soil loss to the water-course. In the case of variants V1, V5, V6 and V7 there was a reduction in water-course capacity of up to 10%. In model Location L2 the variants with relatively greatest ability to reduce potential damage in urban areas were variants V11, V17 and V18. The reduction in average potential damage in the stated variants exceeded the sum of 2.4EUR/m2. © 2014.
Gozlan R.E.,Bournemouth University |
Andreou D.,University of Cardiff |
Asaeda T.,Saitama University |
Beyer K.,SARDI Aquatic Sciences Center |
And 25 more authors.
Fish and Fisheries | Year: 2010
In recent years, policy-makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non-target species that are unknowingly released alongside intentionally-introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported P. parva introduction, mainly resulting from the movement of Chinese carps for fish farming. The mean detection period after first introduction was 4 years, a duration insufficient to prevent their pan-continental invasion. High phenotypic plasticity in fitness related traits such as growth, early maturity, fecundity, reproductive behaviour and the ability to cope with novel pathogens has predisposed P. parva to being a strong invader. The Pseudorasbora parva invasion has provided quantitative data for the development of 1) early warning systems across different spatial scales; 2) rapid eradication programmes prior to natural spread in open systems and 3) sound risk assessments with emphasis on plasticity of life history traits. © 2010 Blackwell Publishing Ltd.
Turek J.,University of South Bohemia |
Randak T.,University of South Bohemia |
Horky P.,TGM Water Research Institute |
Zlabek V.,University of South Bohemia |
And 3 more authors.
Journal of Fish Biology | Year: 2010
The growth, and dispersal of stocked European grayling Thymallus thymallus, reared in a hatchery (fed dry food pellets) or in a pond (fed natural food), compared with their wild conspecifics was assessed from the recapture of individually tagged fish 168 days after their release into the Blanice River, Czech Republic. Recapture rates and site fidelity were higher for wild T. thymallus than for artificially reared fish. Specific growth rate and upstream or downstream dispersal did not significantly differ between any of the groups of fish. An influence of rearing conditions (pond v. hatchery) on the overall performance of stocked fish was not demonstrated. Initially, lower condition factors of reared T. thymallus were equal to wild fish after recapture, suggesting adaptation of artificially reared fish that remained in the sections studied. © 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles.
Valova Z.,Academy of Sciences of the Czech Republic |
Jurajda P.,Academy of Sciences of the Czech Republic |
Janac M.,Academy of Sciences of the Czech Republic |
Bernardova I.,TGM Water Research Institute |
Hudcova H.,TGM Water Research Institute
Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering | Year: 2010
The aim of this study was to assess mercury (Hg), cadmium (Cd) and lead (Pb) contamination in muscle tissue of fishes over the longitudinal profile of the River Morava (Czech Republic, Danube basin) and to detect any temporal trends over the past 18 years. Fish samples were collected in 1992, 1998, 2000, 2003 and 2009 at 6 study sites situated just downstream of important pollution sources. Chub (Leuciscus cephalus L.) were selected as indicator species at 5 sites, and brown trout (Salmo trutta m. fario L.) at the uppermost site where chub do not occur. In total, muscle tissue of 175 specimens of chub and 19 specimens of brown trout were analysed. Concentrations of heavy metals ranged as follows: mercury 0.015-0.369 mg/kg; cadmium 0.001-0.254 mg/kg and lead 0.006-1.505 mg/kg. Mercury levels did not exceed the maximum allowed concentration in the Czech Republic (0.5 mg/kg). Content of cadmium and lead in fish muscle exceeded the maximum allowed levels (0.05 and 0.3 mg/kg respectively) in 11 and 4 samples, respectively. On average, the order of metal concentration in fish muscle was: Hg>Pb>Cd. No significant differences were found between sites along the longitudinal profile of the river. Significant differences were found, however, for the interannual comparison of cadmium and lead (but not mercury) at different sites (P < 0.05). A catastrophic flood in 1997 resulted in an increase in metal concentrations, especially cadmium and lead, in the following 1998 season. Our results indicate that theMorava river basin does not represent a threatening source of mercury, cadmium or lead for the River Danube downstream. Copyright © Taylor & Francis Group, LLC.