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Europe’s recent summer droughts have had devastating ecological and economic consequences, but the severity and cause of these extremes remain unclear. Here we present 27,080 annually resolved and absolutely dated measurements of tree-ring stable carbon and oxygen (δ13C and δ18O) isotopes from 21 living and 126 relict oaks (Quercus spp.) used to reconstruct central European summer hydroclimate from 75 bce to 2018 ce. We find that the combined inverse δ13C and δ18O values correlate with the June–August Palmer Drought Severity Index from 1901–2018 at 0.73 (P < 0.001). Pluvials around 200, 720 and 1100 ce, and droughts around 40, 590, 950 and 1510 ce and in the twenty-first century, are superimposed on a multi-millennial drying trend. Our reconstruction demonstrates that the sequence of recent European summer droughts since 2015 ce is unprecedented in the past 2,110 years. This hydroclimatic anomaly is probably caused by anthropogenic warming and associated changes in the position of the summer jet stream. European summer droughts in recent years are anomalously severe compared with those of the previous 2,000 years, according to a synthesis of annually resolved tree-ring carbon and oxygen isotope records.
Ulf Büntgen; Otmar Urban; Paul J. Krusic; Michal Rybníček; Tomáš Kolář; Tomáš Kyncl; Alexander Ač; Eva Koňasová; Josef Čáslavský; Jan Esper; Sebastian Wagner; Matthias Saurer; Willy Tegel; Petr Dobrovolný; Paolo Cherubini; Frederick Reinig; Miroslav Trnka. Recent European drought extremes beyond Common Era background variability. Nature Geoscience 2021, 14, 190 -196.
AMA StyleUlf Büntgen, Otmar Urban, Paul J. Krusic, Michal Rybníček, Tomáš Kolář, Tomáš Kyncl, Alexander Ač, Eva Koňasová, Josef Čáslavský, Jan Esper, Sebastian Wagner, Matthias Saurer, Willy Tegel, Petr Dobrovolný, Paolo Cherubini, Frederick Reinig, Miroslav Trnka. Recent European drought extremes beyond Common Era background variability. Nature Geoscience. 2021; 14 (4):190-196.
Chicago/Turabian StyleUlf Büntgen; Otmar Urban; Paul J. Krusic; Michal Rybníček; Tomáš Kolář; Tomáš Kyncl; Alexander Ač; Eva Koňasová; Josef Čáslavský; Jan Esper; Sebastian Wagner; Matthias Saurer; Willy Tegel; Petr Dobrovolný; Paolo Cherubini; Frederick Reinig; Miroslav Trnka. 2021. "Recent European drought extremes beyond Common Era background variability." Nature Geoscience 14, no. 4: 190-196.
This paper describes the present applied research focused on pyrolysis oil as one of the three products of sewage sludge (SS) thermal treatment processing—microwave assisted pyrolysis (MAP). Specifically, the full-scale MAP unit with 3 kW magnetron and with the frequency of 2.45 GHz at low pressure conditions is in operation at AdMaS Research Centre, Brno University of Technology (AdMaS BUT). The aim of this paper is to present a chemical characterization of obtained pyrolysis oil together with the suitable analytical determination methods. Detailed characterization of pyrolysis oil from SS was realized by precipitation in n-pentane, fractionation of pentane-soluble part by column chromatography on activated silica by stepwise elution and analysis of obtained fractions by comprehensive orthogonal two-dimensional gas chromatography with time-of-flight mass spectrometric detection. Substances from several groups have been identified at the pyrolysis oil from SS sample: alkanes (110 compounds), alkenes and alkynes (184 compounds), cycloalkanes (104 compounds), aromatic and polyaromatic hydrocarbons (646 compounds), further lower numbers of alcohols, aldehydes, esters, carboxylic acids and heterocycles. The paper also presents a comparison of the above mentioned used two chromatographic methods and imply a basic ecotoxicological test—small algal screening.
Tomáš Chorazy; Josef Čáslavský; Veronika Žvaková; Jakub Raček; Petr Hlavínek. Characteristics of Pyrolysis Oil as Renewable Source of Chemical Materials and Alternative Fuel from the Sewage Sludge Treatment. Waste and Biomass Valorization 2019, 11, 4491 -4505.
AMA StyleTomáš Chorazy, Josef Čáslavský, Veronika Žvaková, Jakub Raček, Petr Hlavínek. Characteristics of Pyrolysis Oil as Renewable Source of Chemical Materials and Alternative Fuel from the Sewage Sludge Treatment. Waste and Biomass Valorization. 2019; 11 (8):4491-4505.
Chicago/Turabian StyleTomáš Chorazy; Josef Čáslavský; Veronika Žvaková; Jakub Raček; Petr Hlavínek. 2019. "Characteristics of Pyrolysis Oil as Renewable Source of Chemical Materials and Alternative Fuel from the Sewage Sludge Treatment." Waste and Biomass Valorization 11, no. 8: 4491-4505.
Mycotoxins are widely studied by many research groups in all aspects, but the stability of these compounds needs further research for clarification. The objective of this study is to evaluate deoxynivalenol and zearalenone stability during all steps of the malting and brewing processes. The levels of these compounds decreased significantly during the production process (barley to beer). During the malting process, the DON levels decreased significantly in the steeping, germination, and malting steps (62%, 51.5%, and 68%, respectively). Considering ZEN, when the levels were compared between barley and the last step of the process, a significant decrease was observed. Most of the mycotoxins produced were transferred to the rootlets and spent grains, which is advantageous considering the final product. Furthermore, the mycotoxin dietary intake estimation was included in this study. The results proved that if the concentrations of target mycotoxins in raw material are under the limits established by the regulations, the levels decrease during the malting and brewing processes and make the beer secure for consumers. The quality of the five commodities involved in the beer process plays a decisive role in the creation of a safe final product.
Karim C. Piacentini; Sylvie Běláková; Karolína Benešová; Marek Pernica; Geovana D. Savi; Liliana O. Rocha; Ivo Hartman; Josef Čáslavský; Benedito Corrêa. Fusarium Mycotoxins Stability during the Malting and Brewing Processes. Toxins 2019, 11, 257 .
AMA StyleKarim C. Piacentini, Sylvie Běláková, Karolína Benešová, Marek Pernica, Geovana D. Savi, Liliana O. Rocha, Ivo Hartman, Josef Čáslavský, Benedito Corrêa. Fusarium Mycotoxins Stability during the Malting and Brewing Processes. Toxins. 2019; 11 (5):257.
Chicago/Turabian StyleKarim C. Piacentini; Sylvie Běláková; Karolína Benešová; Marek Pernica; Geovana D. Savi; Liliana O. Rocha; Ivo Hartman; Josef Čáslavský; Benedito Corrêa. 2019. "Fusarium Mycotoxins Stability during the Malting and Brewing Processes." Toxins 11, no. 5: 257.
This study assessed the state of waters in Belgrade regarding pollution with musk compounds as the target contaminants. Eleven of these compounds were alicyclic, two were macrocyclic, and one was polycyclic. Solid-phase microextraction was used for the isolation of these compounds from waste, surface and underground waters and from processed water prepared for drinking, while comprehensive orthogonal two-dimensional gas chromatography with mass spectrometry was used as the final analytical method. In wastewater samples, galaxolide was detected in concentrations of 1.13 and 0.40 μg/L, while in the Sava River and underground water its concentrations were 0.09 and 0.038 μg/L. The lowest concentrations of the investigated musk compounds were detected in underground water samples, indicating that this is the cleanest water of all the analyzed sources with respect to musk compounds. Comparing the results of musk compound concentrations determined in surface river water samples and clean river water samples utilized for drinking, a lower concentration of these compounds was detected in the clean river water samples. The majority of musk compounds were found in waters utilized for drinking. Based on the concentration values, we conclude that the analyzed waters are moderately polluted with these compounds.
Dubravka Relić; Aleksandar Popović; Dragana Đorđević; Josef Čáslavský. Occurrence of synthetic musk compounds in surface, underground, waste and processed water samples in Belgrade, Serbia. Environmental Earth Sciences 2017, 76, 122 .
AMA StyleDubravka Relić, Aleksandar Popović, Dragana Đorđević, Josef Čáslavský. Occurrence of synthetic musk compounds in surface, underground, waste and processed water samples in Belgrade, Serbia. Environmental Earth Sciences. 2017; 76 (3):122.
Chicago/Turabian StyleDubravka Relić; Aleksandar Popović; Dragana Đorđević; Josef Čáslavský. 2017. "Occurrence of synthetic musk compounds in surface, underground, waste and processed water samples in Belgrade, Serbia." Environmental Earth Sciences 76, no. 3: 122.
Alkaloids known as secondary metabolites are grouped by typical structural characteristics into large families such as pyrrolizidine alkaloids (PAs) comprising more than 350 individual heterocyclic compounds. The PAs present a serious health risk to human and livestock; hence there is a need for methods that allow these dangerous plant toxins to be determined. In this study, a fast, reliable and sensitive approach is proposed to identify and quantify PAs in feed samples. PAs including monocrotaline, senkirkine, senecionine, seneciphylline and retrorsine were determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry. Sample preparation was based on a modified QuEChERS approach. The mean recovery, precision, matrix effects and limits of quantification were assessed for three matrices within the method validation. The presented method was used to inspect 41 various feed samples, where the presence of PAs was expected. Roughages and feed for rabbits contained the highest levels of PAs, in general.
Martina Bolechová; Josef Čáslavský; Markéta Pospíchalová; Petra Kosubová. UPLC–MS/MS method for determination of selected pyrrolizidine alkaloids in feed. Food Chemistry 2015, 170, 265 -270.
AMA StyleMartina Bolechová, Josef Čáslavský, Markéta Pospíchalová, Petra Kosubová. UPLC–MS/MS method for determination of selected pyrrolizidine alkaloids in feed. Food Chemistry. 2015; 170 ():265-270.
Chicago/Turabian StyleMartina Bolechová; Josef Čáslavský; Markéta Pospíchalová; Petra Kosubová. 2015. "UPLC–MS/MS method for determination of selected pyrrolizidine alkaloids in feed." Food Chemistry 170, no. : 265-270.
Martina Bolechová; Karolína Benešová; Sylvie Běláková; Josef Čáslavský; Markéta Pospíchalová; Renata Mikulíková. Determination of seventeen mycotoxins in barley and malt in the Czech Republic. Food Control 2015, 47, 108 -113.
AMA StyleMartina Bolechová, Karolína Benešová, Sylvie Běláková, Josef Čáslavský, Markéta Pospíchalová, Renata Mikulíková. Determination of seventeen mycotoxins in barley and malt in the Czech Republic. Food Control. 2015; 47 ():108-113.
Chicago/Turabian StyleMartina Bolechová; Karolína Benešová; Sylvie Běláková; Josef Čáslavský; Markéta Pospíchalová; Renata Mikulíková. 2015. "Determination of seventeen mycotoxins in barley and malt in the Czech Republic." Food Control 47, no. : 108-113.
The solvent extraction process is regarded amongst other known methods to be applicable for decontamination of sensitive equipment components, especially in cases the components are contaminated in-depth with chemical warfare agents. Viability of the solvent extraction method was evaluated on coupons of butadiene rubber contaminated by sulphur mustard before decontamination by the solvent extraction. The contaminated coupons were extracted in a flow cell, which the solvent (ethoxynonafluorobutane) passed through. Three following specific operational factors, namely the temperature, the flow rate, and the power of ultrasound bath, were assessed for the extent of influencing upon the respective observed extraction efficiencies. The paper describes the results of the evaluation of the solvent extraction effectiveness.Defence Science Journal, 2014, 64(2), pp. 168-172. DOI: http://dx.doi.org/10.14429/dsj.64.3887
Marek Andrle; František Opluštil; Josef Čáslavský. Effects of Ultrasound Power, Temperature and Flow Rate of Solvent on Decontamination of Sensitive Equipment by Extraction. Defence Science Journal 2014, 64, 168 -172.
AMA StyleMarek Andrle, František Opluštil, Josef Čáslavský. Effects of Ultrasound Power, Temperature and Flow Rate of Solvent on Decontamination of Sensitive Equipment by Extraction. Defence Science Journal. 2014; 64 (2):168-172.
Chicago/Turabian StyleMarek Andrle; František Opluštil; Josef Čáslavský. 2014. "Effects of Ultrasound Power, Temperature and Flow Rate of Solvent on Decontamination of Sensitive Equipment by Extraction." Defence Science Journal 64, no. 2: 168-172.
Sylvie Běláková; Karolína Benešová; Josef Čáslavský; Zdeněk Svoboda; Renata Mikulíková. The occurrence of the selected fusarium mycotoxins in Czech malting barley. Food Control 2014, 37, 93 -98.
AMA StyleSylvie Běláková, Karolína Benešová, Josef Čáslavský, Zdeněk Svoboda, Renata Mikulíková. The occurrence of the selected fusarium mycotoxins in Czech malting barley. Food Control. 2014; 37 ():93-98.
Chicago/Turabian StyleSylvie Běláková; Karolína Benešová; Josef Čáslavský; Zdeněk Svoboda; Renata Mikulíková. 2014. "The occurrence of the selected fusarium mycotoxins in Czech malting barley." Food Control 37, no. : 93-98.
Water solutions of organic dye Direct Red 79 were treated by DC high voltage created by diaphragm discharge (input power up to 160 W). Higher dye decoloration (60% after 40 min) was observed in the anode part of the reactor by UV–VIS spectroscopy. Recorded absorption spectra showed shifts of absorption maximum to lower wavelength values that were related to the formation of stable degradation products. Absorption spectra obtained in the cathode part of the diaphragm reactor produced only negligible shifts of absorption maximum and the dye decomposition rate reached 25% after 80 min of the treatment. HPLC-MS method revealed five main compounds in the anode part and another three ones in the cathode part. Analysis of identified products showed on the initial decomposition of one azo-group in the original dye molecule. Significant changes of solution properties during the diaphragm discharge were observed, too. Solution conductivity increased in both parts of the reactor. Solution pH dropped from the initial neutral value to acidic conditions (up to 3) in the anode part and to alkaline conditions (up to 10) in the cathode part. Changes were induced by formation of reactive species by the discharge and by electrochemical reactions on electrodes. Keywords Discharge in water Diaphragm discharge Organic dye decomposition HPLC-MS ESI 1 Introduction Nowadays, high requirements on water quality are desired. Due to the huge amount of wastewaters from plants, industry as well as from households, harmful and hazardous compounds are released into the environment. Common chemical and physical methods used for water purification are not sufficiently effective and moreover, application of chemical agents for compound decomposition could lead to an additional environmental pollution. On the other hand, biological methods have higher efficiency for pollutants removal however, constructions of devices for methods are quite expensive. Following new research activities, huge group of methods belonging among so-called Advanced Oxidation Processes (AOP’s) has been developed during the last few decades [1–8] . The main mechanism of these processes is the creation of chemical reactive species (especially hydroxyl and other radicals as well as ions and molecules with high oxidation potential) [9] that provides subsequent decomposition of molecules dissolved in water or even microbiological decontamination [10] . Utilization of various electrical discharges generated directly in water or near water surface is one of these promising processes for water treatment without additional by-effects. This paper presents results coming from the investigation of so-called diaphragm discharge in order to estimate the removal efficiency of selected organic dye (Direct Red 79) by this discharge. Applying high voltage on electrodes separated by a dielectric barrier (diaphragm) with a small pin-hole in it, the discharge is ignited just in this orifice [11] . Plasma streamers propagating from the pin-hole towards electrodes do not reach electrode surface and thus electrode erosion is minimized as well as electrode lifetime is prolonged in this configuration. If DC high voltage is used for the discharge generation, opposite electrode polarity on both sides of the diaphragm strongly influences both plasma streamers propagation (shape, velocity, energy) and subsequent processes initiated in the reactor [12] . Moreover, high energy supplied into the discharge initiates dissociation and ionisation of water molecules as well as formation of various reactive species such as radicals (hydroxyl, atomic hydrogen and oxygen, etc.), ions and reactive molecules (hydrogen peroxide, ozone, etc.) [9] . Due to their high oxidation potential (2.8 eV for hydroxyl radical [13] ), these species are responsible for consequent chemical reactions that can lead to the destruction of organic compounds dissolved in water. Our previous work has already confirmed decomposition of various organic dyes by the DC diaphragm discharge with respect to the electrode polarity, input power and solution properties (content of supported electrolyte, initial solution conductivity and pH). Obtained results were published in following papers [14–18] . Analyses of treated solutions were carried out by the absorption UV–VIS spectroscopy in order to determine decoloration efficiency of the applied discharge. However, methods of absorption spectroscopy were not convenient for the estimation of degradation products of the dye used. Therefore presented paper presents the newest results obtained from the HPLC-MS analysis and describes dye degradation products and their possible fragmentation schemes in the discharge treatment. 2 Experimental apparatus and methods A special batch discharge reactor was used for organic dye decomposition in water solutions. This device was already described in details in [11] and its simplified scheme and photograph are shown in Figs. 1 and 2 . The reactor was equipped with a changeable diaphragm made of chemically inert and mechanically stable material (PET, thickness of 0.25 mm). One central orifice (initial diameter of 0.25 mm) was drilled in this diaphragm and it was fixed in a plastic wall separating two electrode parts of the reactor. Diameter of the orifice was slightly enhanced and eroded by the discharge operation which led to a minor increase of discharge current and simultaneous decrease of voltage. However, the total discharge power remained constant (160 W) during the treatment. Non-pulsed high DC voltage (up to 2.5 kV) was applied on two planar electrodes (5 × 12 mm) made of stainless steel. Distance between each electrode and the diaphragm was fixed at 20 mm. The main advantage of using DC non-pulsed voltage, comparing to the pulsed regimes [4,5,7] , was a relatively more simple HV source and a substantially lower voltage magnitude required for the discharge ignition (approximately 2 kV...
Zdenka Kozáková; Martin Nejezchleb; František Krčma; Ivana Halamová; Josef Čáslavský; Jindřiška Dolinová. Removal of organic dye Direct Red 79 from water solutions by DC diaphragm discharge: Analysis of decomposition products. Desalination 2010, 258, 93 -99.
AMA StyleZdenka Kozáková, Martin Nejezchleb, František Krčma, Ivana Halamová, Josef Čáslavský, Jindřiška Dolinová. Removal of organic dye Direct Red 79 from water solutions by DC diaphragm discharge: Analysis of decomposition products. Desalination. 2010; 258 (1):93-99.
Chicago/Turabian StyleZdenka Kozáková; Martin Nejezchleb; František Krčma; Ivana Halamová; Josef Čáslavský; Jindřiška Dolinová. 2010. "Removal of organic dye Direct Red 79 from water solutions by DC diaphragm discharge: Analysis of decomposition products." Desalination 258, no. 1: 93-99.
The determination of polychlorinated biphenyls (PCBs) in water, sediment and fish samples from the Czech Republic was carried out using high resolution gas chromatography with electron capture detection. PCBs concentrations in water and sediment samples were rather low and corresponded with the findings from some prior studies. On the other hand, investigated samples of fish tissue were highly contaminated (on average 1.3-266 ng/g fat for individual PCBs), thus, a continuing contamination of fish species with PCBs was proved.
R. Lana; M. Vávrová; J. Čáslavský; M. Skoumalová; A. Bilková; E. Šucman. PCBs in Samples from the Environment of the Southern Moravia Region, Czech Republic. Bulletin of Environmental Contamination and Toxicology 2008, 81, 574 -577.
AMA StyleR. Lana, M. Vávrová, J. Čáslavský, M. Skoumalová, A. Bilková, E. Šucman. PCBs in Samples from the Environment of the Southern Moravia Region, Czech Republic. Bulletin of Environmental Contamination and Toxicology. 2008; 81 (6):574-577.
Chicago/Turabian StyleR. Lana; M. Vávrová; J. Čáslavský; M. Skoumalová; A. Bilková; E. Šucman. 2008. "PCBs in Samples from the Environment of the Southern Moravia Region, Czech Republic." Bulletin of Environmental Contamination and Toxicology 81, no. 6: 574-577.
A library of negative ion electrospray ionization mass spectra and tandem mass spectra (MS/MS) of sulfonated dyes has been developed for fast identification purposes. The uniform protocol has been elaborated and applied to the measurements of more than 50 anionic dyes. Three collision energies are selected in our protocol which ensures that at least one of them provides a suitable ratio of product ions to the precursor ion. The robustness is investigated with altered values of tuning parameters (e.g. the pressure of the nebulizing gas, the temperature and the flow rate of drying gas, and the mobile phase composition). The results of the inter-laboratory comparison of product ion mass spectra recorded on seven different tandem mass spectrometers (three ion traps, two triple quadrupoles and two hybrid quadrupole time of flight instruments) are presented for four representative anionic dyes--azo dye Acid Red 118, anthraquinone dye Acid Violet 43, triphenylmethane dye Acid Blue 1 and Al(III) metal-complex azo dye. The fragmentation patterns are almost identical for all tandem mass analyzers, only the ratios of product ions differ somewhat which confirms the possibility of spectra transfer among different mass analyzers with the goal of library formation.
Kateřina Volná; Michal Holčapek; Lenka Kolářová; Karel Lemr; Josef Čáslavský; Petr Kačer; Jan Poustka; Martin Hubálek. Comparison of negative ion electrospray mass spectra measured by seven tandem mass analyzers towards library formation. Rapid Communications in Mass Spectrometry 2007, 22, 101 -108.
AMA StyleKateřina Volná, Michal Holčapek, Lenka Kolářová, Karel Lemr, Josef Čáslavský, Petr Kačer, Jan Poustka, Martin Hubálek. Comparison of negative ion electrospray mass spectra measured by seven tandem mass analyzers towards library formation. Rapid Communications in Mass Spectrometry. 2007; 22 (2):101-108.
Chicago/Turabian StyleKateřina Volná; Michal Holčapek; Lenka Kolářová; Karel Lemr; Josef Čáslavský; Petr Kačer; Jan Poustka; Martin Hubálek. 2007. "Comparison of negative ion electrospray mass spectra measured by seven tandem mass analyzers towards library formation." Rapid Communications in Mass Spectrometry 22, no. 2: 101-108.
Jaromír Plešek; Bohumír Grüner; Jan Macháček; Ivana Císařová; Josef Čáslavský. 8-Dioxane ferra(III) bis(dicarbollide): A paramagnetic functional molecule as versatile building block for introduction of a Fe(III) centre into organic molecules. Journal of Organometallic Chemistry 2007, 692, 4801 -4804.
AMA StyleJaromír Plešek, Bohumír Grüner, Jan Macháček, Ivana Císařová, Josef Čáslavský. 8-Dioxane ferra(III) bis(dicarbollide): A paramagnetic functional molecule as versatile building block for introduction of a Fe(III) centre into organic molecules. Journal of Organometallic Chemistry. 2007; 692 (22):4801-4804.
Chicago/Turabian StyleJaromír Plešek; Bohumír Grüner; Jan Macháček; Ivana Císařová; Josef Čáslavský. 2007. "8-Dioxane ferra(III) bis(dicarbollide): A paramagnetic functional molecule as versatile building block for introduction of a Fe(III) centre into organic molecules." Journal of Organometallic Chemistry 692, no. 22: 4801-4804.
Calix[4]arene derivatives bearing two residues A(–) derived from cobalt bis(dicarbollide)(1–) (1) and two CMPO groups B at their narrow rim were synthesized from tBu‐calix[4]arene in four steps. The first step involved the preparation of tBu‐calix[4]arene diether derivatives with appropriate precursors for amino groups (mostly nitriles 3). These were O‐alkylated through ring‐opening reactions with the zwitterionic dioxane derivative [(8‐O(CH2CH2)2O‐1,2‐C2B9H10)‐(1′,2′‐C2B9H11)‐3,3′‐Co]0 (10) to produce ionic nitrile derivatives 4. Reduction of the nitrile groups with BH3·SMe2 (or deprotection in the case of the corresponding phthalimido or Boc derivatives 8) led to a series of diamines 5a–f, which were subsequently converted into the corresponding CMPO derivatives 6a–f by acylation with p‐nitrophenyl(diphenylphosphoryl) acetate. Pure cone conformers were isolated in moderate to excellent yields after the second or third reaction step, although the presence of other conformers in the reaction mixtures was sometimes observed by NMR spectroscopy and HPLC, and in one case a di‐A(–)‐di‐B derivative 6c* in the 1,3‐alternate conformation was prepared. The novel ionic ligands 6a–f showed dramatically enhanced extraction abilities for trivalent actinides and lanthanides in relation to the previously reported simple covalent combination of one A(–) with one B group or to various synergistic mixtures of calixarenes substituted exclusively with two A(–) or two B moieties. A 1:1 mixture of calix[4]arenes containing four A(–) anions (13) and four CMPO functions (14), however, showed similarly high extraction efficiency, comparable to that of the best calixarenes 6b–d with mixed substitution. Complexation studies with 6c for La3+, Eu3+ and Yb3+ in methanol carried out by UV spectrophotometry and microcalorimetry revealed the formation of 1:1 and 1:2 metal‐to‐ligand complexes with log β values ranging from 9.6 to 11.7.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Libor Mikulášek; Bohumír Grüner; Crenguta Dordea; Valentyn Rudzevich; Volker Böhmer; Jaouad Haddaoui; Véronique Hubscher-Bruder; Françoise Arnaud-Neu; Josef Čáslavský; Pavel Selucký. tert-Butyl-calix[4]arenes Substituted at the Narrow Rim with Cobalt Bis(dicarbollide)(1–) and CMPO Groups – New and Efficient Extractants for Lanthanides and Actinides. European Journal of Organic Chemistry 2007, 2007, 4772 -4783.
AMA StyleLibor Mikulášek, Bohumír Grüner, Crenguta Dordea, Valentyn Rudzevich, Volker Böhmer, Jaouad Haddaoui, Véronique Hubscher-Bruder, Françoise Arnaud-Neu, Josef Čáslavský, Pavel Selucký. tert-Butyl-calix[4]arenes Substituted at the Narrow Rim with Cobalt Bis(dicarbollide)(1–) and CMPO Groups – New and Efficient Extractants for Lanthanides and Actinides. European Journal of Organic Chemistry. 2007; 2007 (28):4772-4783.
Chicago/Turabian StyleLibor Mikulášek; Bohumír Grüner; Crenguta Dordea; Valentyn Rudzevich; Volker Böhmer; Jaouad Haddaoui; Véronique Hubscher-Bruder; Françoise Arnaud-Neu; Josef Čáslavský; Pavel Selucký. 2007. "tert-Butyl-calix[4]arenes Substituted at the Narrow Rim with Cobalt Bis(dicarbollide)(1–) and CMPO Groups – New and Efficient Extractants for Lanthanides and Actinides." European Journal of Organic Chemistry 2007, no. 28: 4772-4783.
Pressurised fluid extraction using water or methanol was employed for the extraction of stevioside from Stevia rebaudiana Bertoni. The extraction method was optimised in terms of temperature and duration of the static or the dynamic step. Extracts were analysed by liquid chromatography followed by UV and mass-spectrometric (MS) detections. Thermal degradation of stevioside was the same in both solvents within the range 70-160 degrees C. Methanol showed better extraction ability for isolation of stevioside from Stevia rebaudiana leaves than water within the range 110-160 degrees C. However, water represents the green alternative to methanol. The limit of detection of stevioside in the extract analysed was 30 ng for UV detection and 2 ng for MS detection.
Jaroslav Pól; Elena Varaďová Ostrá; Pavel Karásek; Michal Roth; Karolínka Benesová; Pavla Kotlaríková; Josef Cáslavský. Comparison of two different solvents employed for pressurised fluid extraction of stevioside from Stevia rebaudiana: methanol versus water. Analytical and Bioanalytical Chemistry 2007, 388, 1847 -1857.
AMA StyleJaroslav Pól, Elena Varaďová Ostrá, Pavel Karásek, Michal Roth, Karolínka Benesová, Pavla Kotlaríková, Josef Cáslavský. Comparison of two different solvents employed for pressurised fluid extraction of stevioside from Stevia rebaudiana: methanol versus water. Analytical and Bioanalytical Chemistry. 2007; 388 (8):1847-1857.
Chicago/Turabian StyleJaroslav Pól; Elena Varaďová Ostrá; Pavel Karásek; Michal Roth; Karolínka Benesová; Pavla Kotlaríková; Josef Cáslavský. 2007. "Comparison of two different solvents employed for pressurised fluid extraction of stevioside from Stevia rebaudiana: methanol versus water." Analytical and Bioanalytical Chemistry 388, no. 8: 1847-1857.
Single- and multibranched centrosymmetric derivatives incorporating B12 clusters [B12H11−N(H)C(H)-C6H4−C6H4−C(H)=(H)N−B12H11]2- (3) and [1,3,5-(4-(B12H11−N(H)C(H))-C6H4)-C6H3]3- (5) have been synthesized. Both derivatives were characterized by multinuclear NMR and ESI-MS analyses. To the best of our knowledge, compound 5 is the first example of a multicage derivative bearing three B12 units. Compounds 3 and 5 are only slightly yellowish colored. The UV−vis absorption curves of 3 and 5 show intense absorption bands at 360 and 314 nm, respectively. This result permits us to confirm the strong donor effect of the B12 cluster. The hypsochrome effect observed for compound 5 compared to that of compound 3 confirms the interest in multibranched derivatives for the preparation of two-photon absorption materials active in the visible range.
Rémy Bernard; David Cornu; Jean-Pierre Scharff; And Rodica Chiriac; Philippe Miele; Patrice L. Baldeck; Josef Čáslavský. Synthesis, Characterization, and UV−vis Linear Absorption of Centrosymmetric π-Systems Incorporatingcloso-Dodecaborate Clusters. Inorganic Chemistry 2006, 45, 8743 -8748.
AMA StyleRémy Bernard, David Cornu, Jean-Pierre Scharff, And Rodica Chiriac, Philippe Miele, Patrice L. Baldeck, Josef Čáslavský. Synthesis, Characterization, and UV−vis Linear Absorption of Centrosymmetric π-Systems Incorporatingcloso-Dodecaborate Clusters. Inorganic Chemistry. 2006; 45 (21):8743-8748.
Chicago/Turabian StyleRémy Bernard; David Cornu; Jean-Pierre Scharff; And Rodica Chiriac; Philippe Miele; Patrice L. Baldeck; Josef Čáslavský. 2006. "Synthesis, Characterization, and UV−vis Linear Absorption of Centrosymmetric π-Systems Incorporatingcloso-Dodecaborate Clusters." Inorganic Chemistry 45, no. 21: 8743-8748.
The covalent attachment of two CMPO-functions and two anionic Cosan groups to the narrow rim of tert-butylcalix[4]arene leads to a dramatic increase of the extraction efficiency for the cone isomer; Am3+ is removed from 5 × 10−8 M solution to more than 99% by a single extraction step with a 3 × 10−6 M solution of the calixarene.
Libor Mikulášek; Bohumír Grüner; Crenguta Danila; Volker Bőhmer; Josef Čáslavský; Pavel Selucký. Synergistic effect of ligating and ionic functions, prearranged on a calix[4]arene. Chemical Communications 2006, 4001 -4003.
AMA StyleLibor Mikulášek, Bohumír Grüner, Crenguta Danila, Volker Bőhmer, Josef Čáslavský, Pavel Selucký. Synergistic effect of ligating and ionic functions, prearranged on a calix[4]arene. Chemical Communications. 2006; (38):4001-4003.
Chicago/Turabian StyleLibor Mikulášek; Bohumír Grüner; Crenguta Danila; Volker Bőhmer; Josef Čáslavský; Pavel Selucký. 2006. "Synergistic effect of ligating and ionic functions, prearranged on a calix[4]arene." Chemical Communications , no. 38: 4001-4003.
Laser desorption-ionisation/time-of-flight mass spectrometry (LDI/TOF MS) and liquid chromatography/atmospheric pressure chemical ionisation-ion trap mass spectrometry (HPLC/APCI-ITMS) were used for the analysis of polycyclic aromatic hydrocarbons with molecular weight exceeding 278 Da (HMW-PAHs) in air, water and soil samples from the contaminated area of DEZA chemical plant, Valašské Mezříčí, Czech Republic, and from its vicinity. Semipermeable membrane devices (SPMDs) were employed for passive sampling. LDI-TOF MS proved to be a suitable method for quick evaluation of the HMW-PAHs distribution; the presence of PAHs with molecular mass exceeding 500 Da in real samples was proved by this method. Identification and quantitation of individual PAHs was realised using LC/APCI-ITMS. LDI-TOF mass spectra and selected LC/APCI-MS profiles (m/z 303, 327 and 351) were used to confirm the source of contamination by high-molecular-weight PAHs in this area.
Josef Čáslavský; P. Kotlaříková. Analysis of High-Molecular-Weight Polycyclic Aromatic Hydrocarbons by Laser Desorption-Ionisation/Time-of-Flight Mass Spectrometry and Liquid Chromatography/Atmospheric Pressure Chemical Ionisation Mass Spectrometry. Environmental Chemistry 2005, 393 -408.
AMA StyleJosef Čáslavský, P. Kotlaříková. Analysis of High-Molecular-Weight Polycyclic Aromatic Hydrocarbons by Laser Desorption-Ionisation/Time-of-Flight Mass Spectrometry and Liquid Chromatography/Atmospheric Pressure Chemical Ionisation Mass Spectrometry. Environmental Chemistry. 2005; ():393-408.
Chicago/Turabian StyleJosef Čáslavský; P. Kotlaříková. 2005. "Analysis of High-Molecular-Weight Polycyclic Aromatic Hydrocarbons by Laser Desorption-Ionisation/Time-of-Flight Mass Spectrometry and Liquid Chromatography/Atmospheric Pressure Chemical Ionisation Mass Spectrometry." Environmental Chemistry , no. : 393-408.
Non-centrosymmetric π-conjugated systems incorporating closo-dodecaborate clusters, [NC–C6H4–C(H)N(H)–B12H11]− (2), [NC–C6H4–C(H)C(H)–C6H4–C(H)N(H)–B12H11]− (3), and [NC–C6H4–C(H)C(H)–C6H4–C(H)C(H)–C6H4–C(H)N(H)–B12H11]− (4) have been synthesized by reaction of the monoamino derivative of B12, [B12H11NH3]− (1), with various arylaldehydes, R–C6H4–CHO. These Schiff base-like compounds were fully characterized by multinuclear NMR spectroscopy and mass spectrometry. In order to evaluate these boron rich π-systems as potential materials for two-photon absorption (TPA) processes, UV linear absorption curves were recorded for 3 and 4, and comparatively studied with those of the boron-free π-systems NC–C6H4–C(H)N–CH3 (5) and NC–C6H4–C(H)C(H)–C6H4–C(H)N–CH3 (6). The donor effect of the boron cluster was evidenced by a shift to the lower energy of the absorption band in the spectra of systems incorporating B12. The two photon absorption (TPA) spectrum of compound 3, obtained by the up-conversion method, shows a resonance at 720 nm with a cross-section σTPA of 35 × 10−50 cm4 s photon−1 molecule−1. This value suggests the potential of B12 clusters to be used as new donor groups for the synthesis of non-linear materials.
Rémy Bernard; D. Cornu; P. L. Baldeck; J. Čáslavský; J.-M. Letoffe; J.-P. Scharff; Philippe Miele. Synthesis, characterization and optical properties of π-conjugated systems incorporating closo-dodecaborate clusters: new potential candidates for two-photon absorption processes. Dalton Transactions 2005, 3065 -3071.
AMA StyleRémy Bernard, D. Cornu, P. L. Baldeck, J. Čáslavský, J.-M. Letoffe, J.-P. Scharff, Philippe Miele. Synthesis, characterization and optical properties of π-conjugated systems incorporating closo-dodecaborate clusters: new potential candidates for two-photon absorption processes. Dalton Transactions. 2005; (18):3065-3071.
Chicago/Turabian StyleRémy Bernard; D. Cornu; P. L. Baldeck; J. Čáslavský; J.-M. Letoffe; J.-P. Scharff; Philippe Miele. 2005. "Synthesis, characterization and optical properties of π-conjugated systems incorporating closo-dodecaborate clusters: new potential candidates for two-photon absorption processes." Dalton Transactions , no. 18: 3065-3071.
Semipermeable membrane devices (SPMDs) are nowadays used as passive samplers of organic pollutants. The knowledge of the sampling rate values ( R S) of each substance trapped on membranes is necessary to calculate their average concentration. Here we calculate R S values for 16 polycyclic aromatic hydrocarbons using the comparison of active sampling method results and the amounts sequestered by SPMDs at varying exposure times.
J. Caslavsky; P. Kotlaříková; K. Benešová. Sampling of airborne polycyclic aromatic hydrocarbons with semipermeable membrane devices. Environmental Chemistry Letters 2004, 2, 89 -92.
AMA StyleJ. Caslavsky, P. Kotlaříková, K. Benešová. Sampling of airborne polycyclic aromatic hydrocarbons with semipermeable membrane devices. Environmental Chemistry Letters. 2004; 2 (2):89-92.
Chicago/Turabian StyleJ. Caslavsky; P. Kotlaříková; K. Benešová. 2004. "Sampling of airborne polycyclic aromatic hydrocarbons with semipermeable membrane devices." Environmental Chemistry Letters 2, no. 2: 89-92.
Polycyclic aromatic hydrocarbons (PAHs) with molecular weight exceeding 278 amu were analyzed in air, water, and soils from the area and vicinity of the DEZA Chemical Plant (Vala w ské Mezi q í ) í, Czech Republic). Air and water were sampled using semipermeable membrane devices (SPMDs); grab sampling was applied for soils. Laser desorption/ionization-time-of-flight mass spectrometry (LDI-TOF MS) and liquid chromatography/ion trap mass spectrometry with atmospheric pressure chemical ionization (LC/APCI-ITMS) were employed for the quick assessment of PAH distribution and for the identification and quantification of some high-molecular-weight PAHs. Compounds with molecular mass up to 450 u were found. LDI-TOF mass spectra and selected LC/APCI-ITMS profiles (m/z 303, m/z 327, and m/z 351) were compared to identify potential source of contamination in this locality. High-molecular-weight PAHs were found in all environmental compartments in the area studied; their levels were quite high close to their source and decreased sharply with increasing distance from it.
Josef Caslavsky; Pavla Kotlaríková. High-Molecular-Weight Polycyclic Aromatic Hydrocarbons in the Area and Vicinity of the Deza Chemical Plant, Czech Republic. Polycyclic Aromatic Compounds 2003, 23, 327 -352.
AMA StyleJosef Caslavsky, Pavla Kotlaríková. High-Molecular-Weight Polycyclic Aromatic Hydrocarbons in the Area and Vicinity of the Deza Chemical Plant, Czech Republic. Polycyclic Aromatic Compounds. 2003; 23 (3):327-352.
Chicago/Turabian StyleJosef Caslavsky; Pavla Kotlaríková. 2003. "High-Molecular-Weight Polycyclic Aromatic Hydrocarbons in the Area and Vicinity of the Deza Chemical Plant, Czech Republic." Polycyclic Aromatic Compounds 23, no. 3: 327-352.