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11.
12.
Erzsébet Háznagy-Radnai Edit Wéber Szilvia Czigle Róbert Berkecz Károly Csedő Judit Hohmann 《Chromatographia》2014,77(17-18):1153-1159
Melampyrum bihariense A. Kern. (Scrophulariaceae), a plant species used in traditional medicine for the treatment of rheumatic disorders and skin infections, was investigated with regard to its antioxidant activity and identification of its bioactive chemical constituents. The crude methanolic extract of the aerial parts of M. bihariense was examined by the spectrophotometric DPPH (1,1-diphenyl-2-picrylhydrazyl) and ferric reducing antioxidant power methods. The free radical scavenging capacity (SC50) of the extract was found by the DPPH method to be 27.10 mg mL?1, and the ferric reducing ability equivalent to ascorbic acid at 50 mg mL?1 was 0.709 μg mL?1. The chemical composition of this highly effective in the methanolic extract was analysed, and the main compounds were isolated through solvent–solvent partition, and multiple chromatographic separations, including column chromatography, vacuum liquid chromatography, centrifugal planar chromatography and preparative thin-layer chromatography. The structures were established by one- and two-dimensional NMR and liquid chromatography-mass spectrometry. The iridoids aucubin (1), 8-epi-loganin (2) and mussaenoside (3), the flavones apigenin and luteolin and the triterpene acids ursolic acid and oleanolic acid were identified; components 2, 3, ursolic acid and oleanolic acid for the first time in this species. The present study reveals that M. bihariense exerts antioxidant activity, and the iridoids, flavonoids and triterpene acids may be the main bioactive constituents of its methanolic extract. 相似文献
13.
Tóth A Törocsik A Tombácz E Oláh E Heggen M Li C Klumpp E Geissler E László K 《Journal of colloid and interface science》2011,364(2):469-475
We report the adsorption of phenol and dopamine probe molecules, from aqueous solution with NaCl, on commercial multiwall carbon nanotubes (MWCNT) and on their carboxylated derivative. The nanotubes were fully characterized by high resolution transmission electron microscopy (HRTEM), small angle X-ray scattering (SAXS), potentiometric titration, electrophoretic mobility, and nitrogen adsorption (77K) measurements. The experimental pollutant isotherms, evaluated using the Langmuir model, showed that only 8-12% and 21-32% of the BET surface area was available for phenol and dopamine, respectively, which is far below the performance of activated carbons. Influence of the pH was more pronounced for the oxidized MWCNT, particularly with dopamine. The strongest interaction and the highest adsorption capacity occurred at pH 3 with both model pollutants on both types of nanotubes. Although the surface area available for adsorption is far lower in MWCNTs than in activated carbons, it is nonetheless substantial. In particular, delayed release of toxic molecules that are either adsorbed on the surface or trapped in the inner bore of such systems could constitute an environmental hazard. The need for further adsorption studies with regard to their environmental aspects is therefore pressing, particularly for MWCNTs in their functionalized state. 相似文献
14.
The root and leaf essential oils, present in trace amounts in Amsonia illustris Woods. (Apocynaceae), were isolated by steam distillation and their chemical constituents identified by GC-FID and GC-MS. More than 80% of the thirty volatile compounds in the leaf oil were identified, the major constituents being mainly sesquiterpenes like a-humulene (14.5%), beta-caryophyllene (12.4%) and guaiol (11.6%). The volatile ingredients of the root oil were pinocampheol, methyl salicylate, (2E,4E)- decadienal, eugenol and trans-isoeugenol. 相似文献
15.
Stefan Jopp Tina Wallaschkowski Peter Ehlers Eva Frank Gyula Schneider János Wölfling Erzsébet Mernyák Alexander Villinger Peter Langer 《Tetrahedron》2018,74(23):2825-2836
4-Bromo-3-O-triflyl-estrone has been synthesized in 2 steps from estrone and was successfully employed in chemoselective palladium catalysed Suzuki-Miyaura reactions. Mono- and bis-arylations were carried out selectively by variation of ligands and solvents. Overall 19 derivatives of mono- and bis-arylated estrones were synthesized under optimized conditions in high yields. Various products showed atropisomerism which was studied in detail by NMR spectroscopy. 相似文献
16.
Veronika Vágvölgyi M. Hales W. Martens J. Kristóf Erzsébet Horváth R. L. Frost 《Journal of Thermal Analysis and Calorimetry》2008,92(3):911-916
The understanding of the thermal stability of zinc carbonates and the relative stability of hydrous carbonates including hydrozincite
and hydromagnesite is extremely important to the sequestration process for the removal of atmospheric CO2. The hydration-carbonation or hydration-and-carbonation reaction path in the ZnO-CO2-H2O system at ambient temperature and atmospheric CO2 is of environmental significance from the standpoint of carbon balance and the removal of green house gases from the atmosphere.
The dynamic thermal analysis of hydrozincite shows a 22.1% mass loss at 247°C. The controlled rate thermal analysis (CRTA)
pattern of hydrozincite shows dehydration at 38°C, some dehydroxylation at 170°C and dehydroxylation and decarbonation in
a long isothermal step at 190°C. The CRTA pattern of smithsonite shows a long isothermal decomposition with loss of CO2 at 226°C. CRTA technology offers better resolution and a more detailed interpretation of the decomposition processes of zinc
carbonate minerals via approaching equilibrium conditions of decomposition through the elimination of the slow transfer of
heat to the sample as a controlling parameter on the process of decomposition. The CRTA technology offers a mechanism for
the study of the thermal decomposition and relative stability of minerals such as hydrozincite and smithsonite. 相似文献
17.
Y. Zhao R. L. Frost Veronika Vágvölgyi E. R. Waclawik J. Kristóf Erzsébet Horváth 《Journal of Thermal Analysis and Calorimetry》2008,94(1):219-226
Yttrium doped boehmite nanofibres with varying yttrium content have been prepared at low temperatures using a hydrothermal
treatment in the presence of poly(ethylene oxide) surfactant (PEO). The resultant nanofibres were characterized by X-ray diffraction
(XRD) and transmission electron microscopy (TEM). TEM images showed the resulting nanostructures are predominantly nanofibres
when Y-doping is less than 5%; in contrast Y-rich phases were formed when doping was around 10%.
The doped boehmite and the subsequent nanofibres/nanotubes were analyzed by thermogravimetric and controlled rate thermal
analysis methods. The boehmite nanofibres produced in this research thermally transform at higher temperatures than boehmite
crystals and boehmite platelets. Boehmite nanofibres decompose at higher temperatures than non-hydrothermally treated boehmite. 相似文献
18.
L. Benkő J. Danis R. Hubmann G. Kasza Éva Gömöri Erzsébet Rőth D. Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2009,95(3):763-768
Massive bleeding from esophagus varices presents a life threatening complication of portal hypertension. No effective method
of treatment is available until now, that would guarantee high grade of patient wellness during the conditioning and investigation
phase until the definitive treatment could be introduced. The aim of this study was to evaluate the tissue response to esophagus
stents - designed for manage acute variceal bleeding - in animal experiment.
Self-expandable nitinol stents were introduced into the esophagus of six porcines. Another twelve porcines were undergone
the same procedure, using the new biodegradable stents made of PDO (polydioxanon). Histological investigations of the stented
esophagus segments were observed after 2 and 4 weeks at the first 12 animals. To monitor the time of stent degradation, histology
were performed 7 and 12 weeks after the implantation in the biodegradable group (3–3 animals). Differential scanning calorimetric
examination was performed in all esophagus samples.
Focal erosion of the esophagus segments was more explicit in the nitinol group at the histology. On the 7th week all of the biodegradable stent were in the stomach and on the 12th week these were completely solved. DSC examination showed significant alterations in the structure of the esophagus in both
stented group compared to the healthy control.
This experiment showed that the new self-expandable stents are safety and suitable procedure without deterioration of the
esophageal wall. According to our DSC results the thermal denaturation of intact esophagus, its mucosa and muscle fragments
revealed significant differences compared to healthy sample in favour the new biodegradable stent. Safety and efficiency in
the experimental model had encouraged us to apply this method successfully patients with bleeding esophagus varices. The long
term goal is to show that stent placement could be an effective way of decreasing or stabilising the acute bleeding from ruptured
esophagus varices in cirrhotic patients. 相似文献
19.
Klára Nedvig Andrea Ferencz Erzsébet Rőth D. Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2009,95(3):775-779
The fact that small bowel is extremely sensitive to ischemia/reperfusion (I/R) injury had encouraged us to compare the conventional
histology and differential scanning calorimetry (DSC) methods in intestinal structural changes following experimental warm
I/R models. Our histological findings showed that longer warm I/R period caused more severe damage in structure of mucosa
and crypts, but there were no changes in the muscular layer. According to our DSC data (transition temperature, calorimetric
enthalpy) suggest that the thermal destruction of mucosa, muscular layer and total intestinal wall following I/R injury revealed
significant differences compared to normal bowel structure. 相似文献
20.
Erzsébet Néher-Neumann 《Journal of solution chemistry》2006,35(8):1085-1107
Equations are derived for the calculation of the total potential anomalies in Emf cells with liquid junctions (ΔE
J
) in mV and at 25.0 °C, defined as
wherez
j
= the charge number of the potential determining ion, J, and TS2 = terminal solution 2 ≡ test solution. This definition includes the activity factor (f
J
) contributions to the measuring electrode, the ideal diffusion potential (E
D
) and the contribution of the activity factors to E
D
, denoted by E
Df
. The cell assumed to contain an equilibrium solution which exists in the system, HY – BY
z(B)–A
y
L in the ionic medium (A+, Y−) with the experimental condition I (ionic strength) = CM, constant, in the mixed solutions. Here, L
y
− denotes the ligand and B
z
(B)+ the metal ions.The reasons for the dependence of the equilibrium constants on the ionic medium are given. The change of the equilibrium constants with the experimental conditions in a given ionic medium is also explained. 相似文献