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21.
Repáková J Holopainen JM Karttunen M Vattulainen I 《The journal of physical chemistry. B》2006,110(31):15403-15410
We elucidate the influence of pyrene-labeled phospholipids on the structural properties of a fluid dipalmitoylphosphatidylcholine lipid membrane. To this end, we employ extensive atomic-scale molecular dynamics simulations with varying concentrations of pyrene-linked lipids. We find pyrene labeling to perturb the membrane structure significantly in the vicinity of the probe, the correlation length in the bilayer plane being about 1.0-1.5 nm. The local perturbations lead to enhanced ordering and packing of lipid acyl chains located in the vicinity of the probe. Surprisingly, this holds true not only for lipids that reside in the same leaflet as the pyrene-labeled probe but also for lipids in the opposite monolayer. The latter is due to substantial interdigitation of the pyrene moiety into the opposite leaflet, suggesting that occasional excimer formation may take place for probes in different leaflets. As a related issue, we also discuss the location and conformational orientation of the pyrene moieties. In particular, the orientational distribution of pyrene turns out to be more broad and diverse than the distribution of the corresponding acyl tails of nonlabeled lipids. 相似文献
22.
Martina Hribova Frantisek Rybnikar Jarmila Vilcakova 《Journal of Macromolecular Science: Physics》2013,52(1):16-25
Microscopical, differential scanning colorimetry (DSC), and X-ray structural investigations of solution crystallized carbon nanotube (CNT) composites with linear polyethylene (LPE), isotactic polypropylene (iPP), polybutene-1 (PB-1), and nylon 6 (PA6) disclosed varying degrees of surface interaction and nucleation effect of CNT in these polymers and formation of oriented shish-kebab overgrowths on the CNT ropes in LPE and PA6. The character of the attraction and orientation forces at the CNT-polymer interface is discussed. 相似文献
23.
Aluminium based rapidly quenched alloys of nominal composition Al90Fe7Nb3 and Al94Fe2V4 were studied by Mössbauer spectroscopy. Samples annealed up to 573 K showed amorphous structure represented by quadrupole doublet. From corrected spectra areas the values of f-factor were calculated. In the case of AlFeNb samples f-factor was estimated as f = 0.26 and for AlFeV f = 0.31. The corresponding Debye temperatures were also calculated. Higher temperature annealing at 773 and 873 K induced deformation of nano- and microcrystalline state. Mössbauer spectra of samples of both compositions (with vanadium as well as with niobium) annealed at 773 K showed superposition of crystalline phases with dominant role of Al3Fe alloy. During annealing at 873 K, phases with large grains and small amount of FeAl metastable phase were developed (Das et al. Mat. Sci. Eng., A304–A306, 159, 2001; Illeková et al. Mat. Sci. Eng., A375–A377, 946, 2004). 相似文献
24.
25.
Jarmila Dolejší Josef Kantůrek Antonín Bohun Jaroslav Trnka 《Czechoslovak Journal of Physics》1958,8(5):548-555
Zusammenfassung
Anführung der Ergebnisse eines komplexen Studiums einiger optischer und elektrischer Erscheinungen bei natürlichen und künstlichen Kristallen von CaF2
verschiedener Herkunft, die photochemisch, additiv oder gleichzeitig auf beide Arten (kombiniert) gefärbt waren. Untersucht wurden vor allem die Absorption bei konstanter und gleichmäßig ansteigender Temperatur (Thermoabsorption), die integrale Lumineszenz und deren Spektralanalyse und die Exoelektronenemission.Auszug aus einem Artikel, der in tschechischem Wortlaut in der Zeitschr. s. as. Fys.8 (1958) veröffentlicht wurde. 相似文献
26.
Ondřej Kaman Tereza Dědourková Jakub Koktan Jarmila Kuličková Miroslav Maryško Pavel Veverka Radim Havelek Karel Královec Karolína Turnovcová Pavla Jendelová Adam Schröfel Ladislav Svoboda 《Journal of nanoparticle research》2016,18(4):100
Magnetic oxide nanoparticles provide a fascinating tool for biological research and medicine, serving as contrast agents, magnetic carriers, and core materials of theranostic systems. Although the applications rely mostly on iron oxides, more complex oxides such as perovskite manganites may provide a much better magnetic performance. To assess the risk of their potential use, in vitro toxicity of manganite nanoparticles was thoroughly analysed and compared with another prospective system of Mn–Zn ferrite nanoparticles. Magnetic nanoparticles of La0.63Sr0.37MnO3 manganite were prepared by two distinct methods, namely the molten salt synthesis and the traditional sol–gel route, whereas nanoparticles of Mn0.61Zn0.42Fe1.97O4 ferrite, selected as a comparative material, were synthesized by a new procedure under hydrothermal conditions. Magnetic cores were coated with silica and, moreover, several samples of manganite nanoparticles with different thicknesses of silica shell were prepared. The size-fractionated and purified products were analysed using transmission electron microscopy, dynamic light scattering, measurement of the zeta-potential dependence on pH, IR spectroscopy, and SQUID magnetometry. The silica-coated products with accurately determined concentration by atomic absorption spectroscopy were subjected to a robust evaluation of their cytotoxicity by four different methods, including detailed analysis of the concentration dependence of toxicity, analysis of apoptosis, and experiments on three different cell lines. The results, comparing two manganese-containing systems, clearly indicated superior properties of the Mn–Zn ferrite, whose silica-coated nanoparticles show very limited toxic effects and thus constitute a promising material for bioapplications. 相似文献
27.
JPC – Journal of Planar Chromatography – Modern TLC - Alternaria alternata is an important mycotoxin-producing species that occurs on cereals, sunflower seeds, oilseed rape, tomato,... 相似文献
28.
Svetlana Hrouzková Eva Matisová Mária Andraščíková Matej Horváth Renáta Húšková Jarmila Ďurčanská 《International journal of environmental analytical chemistry》2013,93(13):1546-1562
The search on endocrine disrupting chemicals (EDCs) in non-fatty food was evaluated. A fast, high-throughput, accurate, multiresidue method for the analysis of selected EDC pesticides in fruit and vegetable food samples was developed. The QuEChERS technique was used for sample preparation. Fast GC-MS was performed with a narrow-bore capillary column and a quadrupole benchtop detector with electron ionization (EI) and negative chemical ionization (NCI). A part of the work was devoted to the comparison of NCI versus EI approach concerning the sensitivity of detection and to the study of selectivity enhancement in NCI mode. Matrix-matched standard solutions were utilized for calibration. The methods validation was performed. Fortification studies at 1, 5, 10 and 250?µg?kg?1 for 35 pesticides in EI mode and 0.1, 1, 5 and 250?µg?kg?1 for 28 pesticides in NCI mode were performed. Average recoveries for each fortification level ranged from 70 to 110% with >80% of recoveries between 90 and 110%. Limits of quantification (LOQs) were established at 5?µg?kg?1 for EI and at 1?µg?kg?1 for NCI mode, which is lower than the lowest maximum residue level (MRL) value set by the European Commission in fruit and vegetables. The developed and validated fast GC-MS method was successfully applied to the search of EDC pesticides at ultratrace concentration level in real fruit and vegetable samples in Slovakia. Thirty-four samples of 20 different commodities were analyzed. Seven samples contained residues of three or more EDCs pesticides. 相似文献
29.
Jana Blašková Viera Vojteková Jarmila Nováková Daniela Mackových Yaroslav Bazeľ Lubomír Lapčík Zuzana Poperníková Ashraf M. M. Abusenaina 《Central European Journal of Chemistry》2013,11(7):1201-1212
Application of economically important and time saving pretreatment for the screening element mobility evaluation of contaminated sediments is presented. Ultrasonically-assisted single-step extraction (USAE) was carried out by EDTA solution. The extraction time of USAE was optimized and obtained results were compared with results estimated by conventional (EDTA extraction) and by sequential extraction (modified BCR protocol). The original three step BCR protocol was modified by addition of the first step (water leaching) and the fifth step, total digestion of sediment residue (acid mixture with HF). Zn, Cu and Pb have been determined in extracts by ICP-OES. Good conformity of the ultrasonically-extracted element contents and sum of contents, extracted during first three steps (water-soluble, acid-extractable, reducible — i.e., the most mobile fractions) of sequential extraction, was found. The sono-extraction reduced operating time of the first three steps of sequential extraction from 48 h to 15 min. Thus, USAE can serve as a rapid screening assessment of the mobile and potentially mobile element portions in sediments and other similar solid state environmental media. Analytical quality control was realized by comparison of the sums of element contents obtained at individual (five) extraction steps. Total element contents were also determined by an independent method (XRF). 相似文献
30.
Lukáš Gál Michal Čeppan Milena Reháková Vladimír Dvonka Jarmila Tarajčáková Jozef Hanus 《Analytical and bioanalytical chemistry》2013,405(28):9085-9091
A method has been developed for identification of corrosive iron–gall inks in historical drawings and documents. The method is based on target-factor analysis of visible–near infrared fibre optic reflection spectra (VIS–NIR FORS). A set of reference spectra was obtained from model samples of laboratory-prepared inks covering a wide range of mixing ratios of basic ink components deposited on substrates and artificially aged. As criteria for correspondence of a studied spectrum with a reference spectrum, the apparent error in target (AET) and the empirical function SPOIL according to Malinowski were used. The capability of the proposed tool to distinguish corrosive iron–gall inks from bistre and sepia inks was evaluated by use of a set of control samples of bistre, sepia, and iron–gall inks. Examples are presented of analysis of historical drawings from the 15th and 16th centuries and written documents from the 19th century. The results of analysis based on the tool were confirmed by XRF analysis and colorimetric spot analysis. Figure
Sitting Evangelist, Bartolomeo Passarotti, 16th century, Slovak National Gallery, Bratislava, Slovak Republic, Inventory No. K 96 相似文献