Mihály Óvári

Rhodium-catalyzed hydrogenation of olefins in γ-valerolactone-based ionic liquids

γ-Valerolactone-based ionic liquids were successfully used as the catalyst phase for [Rh(cod)2][BF4]/RP(C6H4-m-SO3Na)2 (R = Me, Pr, Bu, Cp) catalyzed hydrogenation of different olefins. Compared to broadly used ionic liquids e.g. 1-butyl-3-methylimidazolium chloride [bmim][Cl], the turnover frequencies were significantly higher and the reaction was selective for the CC double bonds in the presence of carbonyl, cyano, and phenyl groups. The catalyst was recycled for ten consecutive runs under regular or biphasic conditions without loss of activity. The vapour pressure and viscosity of γ-valerolactone-based ionic liquids were determined as well.

Investigation into the mechanism of stimulation by low-concentration stressors in barley seedlings

Beneficial effects of low-concentration chemical stressors have been investigated previously in different model systems. The symptoms of stimulation are known from earlier studies, but information about the mechanism is at an initial stage. In the present work, the mechanism of stimulation of low-concentration Cd (5 x 10(-8)M) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU, 10(-7)M) was investigated in barley seedlings. In treated plants, the amount of cytokinins increased in roots and, after being transported to the leaves, they caused stimulation there. To identify the signal transduction pathway(s) involved in the primary stimulation of cytokinin synthesis (and/or activation) in roots, specific phosphatidylinositol-4,5-bisphosphate-inositol-1,4,5-triphosphate/diacylglycerol (PIP(2)-IP(3)/DAG) and mitogen activated protein kinase (MAPK) signaling pathway inhibitors were added to the nutrient solution, and all proved to be effective, eliminating the stimulation by the stressors. Measurements of superoxide dismutase (SOD, EC 1.15.1.1) activity and the amount of malonyldialdehyde (MDA) showed that the increased amount of Cd did not cause oxidative stress in the roots, and no oxidative stress was found in the leaves, where Cd did not even accumulate. DCMU slightly increased the activity of SOD after 1 week in roots, but did not cause lipid peroxidation. In leaves, there was no oxidative stress upon treatment with DCMU. Thus, oxidative stress cannot be responsible for the stimulation with low-concentration stressors, as they changed the activity of SOD differently, while being equally stimulative for the plants.

The use of a portable total reflection X-ray fluorescence spectrometer for field investigation ☆

b ´ Abstract A newly developed, portable total reflection X-ray fluorescence (TXRF) spectrometer was tested during a field campaign on Chilean lakes and a German river in January 2002. The field measurements were compared with laboratory measurements carried out on a stationary instrument in the German laboratory. For method validation certified reference material (NIST SRM 1640 Trace elements in natural water) and water samples from different freshwater sources were analyzed with both techniques and evaluated statistically. Based on these preliminary results, it could be concluded that the portable TXRF is a useful technique for the quantitative elemental screening of freshwater samples during field campaigns. Future tests with biological samples (e.g. biofilms and zooplankton), and suspended matter will provide information about the suitability of the portable TXRF for these materials. 2003 Elsevier B.V. All rights reserved.

On the mechanism of rejuvenation of ageing detached bean leaves by low-concentration stressors.

The effect of low concentrations of some stress-inducing compounds of different toxicity and chemical nature, such as Cd and Pb salts or DCMU, was investigated on the senescence of chloroplasts in detached primary leaves of bean (Phaseolus vulgaris L.). After 1 week of senescence followed by root development from the petiole, these agents stimulated chlorophyll accumulation and photosynthetic activity ((14)CO(2) fixation) as compared to the control, thus inducing rejuvenation. Low-concentration stressors increased the level of active cytokinins in roots and leaves during the treatment, as monitored by the Amaranthus betacyanin bioassay and high-pressure liquid chromatography. The lithium ion, an inhibitor of the PIP(2)-IP(3)/DAG signal transduction pathway, abolished the stimulating effect of stressors, both in roots (retarding cytokinin synthesis) and consequently also in leaves (reducing cytokinin-dependent chlorophyll accumulation). This suggests the involvement of the PIP(2)-IP(3)/DAG signal transduction pathway in generation of these consecutive organ-specific responses.

Solid sampling electrothermal vaporization inductively coupled plasma atomic emission spectrometric method for analysis of amphipods (Dikerogammarus villosus) samples

A solid sampling electrothermal vaporization inductively coupled plasma atomic emission spectrometric (ETV-ICP-AES) method was developed for determination of Ag, Cd, Co, Cu, Mn, Pb and Zn in amphipods (Dikerogammarus villosus) applied for river water monitoring. The organic part of the dried and homogenized samples was decomposed at 450 °C in a quartz boat. Ashed sample (2 mg) was weighed into the graphite boat and the carbonates were decomposed by addition of 40 μl 1 M nitric acid. The dried inorganic residue was introduced into the graphite furnace and vaporized at 1350 °C applying Freon 22 gaseous halogenating agent. The calibration was carried out by dry residues of standard solutions. The same amphipod sample was digested and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The analytical results show a difference between 2 and 25%.

Reference concentrations of trace elements in urine of the budapestian population

Reference values in biological specimens are crucial to estimate the type and magnitude of environmental and occupational exposure: Because of its importance in the excretion of noxious substances and to the noninvasive mode of its collection, urine is a useful specimen for monitoring studies. Thus, the concentrations of six trace elements (Al, Co, Mo, Nb, Ni, and Ti) were determined in 100 urine samples of the Budapestian population by inductively coupled plasma-mass spectrometry. The obtained creatinine adjusted concentrations (medians) are (in μg/g) 9.9, 0.6, 53.5, 0.4, 1.5, and 8.5 for Al, Co, Mo, Nb, Ni, and Ti, respectively.

Elemental analysis of Dikerogammarus villosus samples for river water monitoring

Dikerogammarus villosus (amphipod crustacean) samples were collected from the River Danube. The applicability of artificial substrates (gravel and clay filled containers translocated at the bottom of the river) and the effect of the applied colonization periods of short (3 weeks) and long (up to 30 weeks) terms were tested. Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn concentrations of the amphipods were measured by inductively coupled plasma mass spectrometry (ICP-MS) after the digestion of some milligram samples. It was established that the artificial substrates did not influence the bioaccumulative processes of the elements investigated, and the short-term colonization period turned out to be sufficient for biomonitoring.

Recently forming stalagmites from the Baradla Cave and their suitability assessment for climate–proxy relationships

Determination of the long-term behavior of cave systems and their response to changing environmental conditions is essential for further paleoclimate analyses of cave-hosted carbonate deposits. For this purpose, four actively forming stalagmites were collected in the Baradla Cave where a three-year monitoring campaign was also conducted. Based on textural characteristics and radiocarbon analyses, the stalagmites are composed of annual laminae, whose counting was used to establish age–depth relationships. Fast and slowly growing stalagmites have different stable carbon and oxygen isotope compositions as well as trace element contents that could be attributed to differences in drip water migration pathways. The stable isotope compositions were compared with meteorological data of the last ∼100 years indicating that carbon isotope compositions of the stalagmites may reflect changes in precipitation amount, while oxygen isotope compositions are more related to temperature variations. The combined textural–geo...

Investigation of distribution of beryllium, nickel and vanadium in subsoil of Csepel-Island

Abstract In order to investigate the long-term effect of the Szazhalombatta power plant on the environment of the Csepel-Island subsoil samples were collected in 55 points within 200 km2. Using a microwave-assisted extraction procedure, Be, Ni and V were extracted from the soil samples by aqua regia and the metal concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS). The analytical results were evaluated by chemometric methods and interpreted considering the main mineral constituents of the subsoil.

Effect of variety of grapes on trace element and ochratoxin A contents of Hungarian red wines

The quality of wines depends on the soil, the climatic circumstances, the technology, and the variety of grapes. Since the Egri Bikavér (Bulls blood of Eger) is a cuvee wine, for its production, different 1-year-old red wines (Blauburger, Cabernet sauvignon, Cabernet franc, Kékfrankos, Merlot) are mixed in well-selected ratios. Our investigations were focused on red wines of 2007 vintage produced by the same technology from five different varieties of grapes cultivated in the same agricultural area and on the Bikavér produced in 2006 by the mixing of five different 1-year-old wines as mentioned above. The concentration of trace elements and ochratoxin A were determined by inductively coupled plasma sector field mass spectrometry and high-performance liquid chromatography techniques, respectively. It was established that the variety of grapes produced at the same territory has practically no influence on the trace element concentration of the investigated red wines. In addition, the concentration of ochratoxin A has remained in all cases <0.1 µg L−1, considerably lower than the European regulatory limit of 2 µg L−1.