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1.
Jirina Sysalova Jirina Szakova Walter Goessler Jana Tremlova 《Central European Journal of Chemistry》2011,9(6):1071-1079
The modified BCR three-step sequential extraction procedure has been applied to two different samples of urban particulate
matters (PM). The distribution of selected trace elements As, Cd, Cr, Mn, Ni, Pb, Zn was investigated and, in a comparative
study, the presence of common organic air filters in extraction procedures was evaluated. Analytes in separate fractions were
determined by ICP-OES and GFAAS, respectively, depending on concentration levels. While, due to air filters, a significant
increase of some analytes mobility in individual fractions has been observed in case of the jet-milled PM (tunnel Letna),
but in case of the PKC sample such effect was not found. The analyte impurities built in some filters has been tested, and
the impact on the reliability of analyte results has been discussed. The arsenic species occurrence and their stability in
presence of air filters (size 47 mm) were investigated in both urban PM samples as well, using HPLC-ICP-MS technique. Water
soluble and by three-step BCR procedure extractable arsenic forms are shown in chromatograms 相似文献
2.
Miloslav Jirina 《Monatshefte für Mathematik》1982,94(2):103-107
Intervals in which Lagrange interpolation polynomials converge pointwise to the interpolated function are specified for a family of functions comprising all completely monotone functions. 相似文献
3.
Mineralization procedures for blood and urine suitable for the determination of arsenic by Hydride Generation Atomic Absorption
Spectrometry (HGAAS) are studied on model samples, and the results are utilized in biological monitoring investigations. The
objective of this work is to obtain good total As recoveries for both matrices regardless of added As species (As(III), As(V),
DMA, MMA, AsB, or AsC). Prior to the HGAAS analyses, preparation procedures were controlled under optimised conditions by
graphite furnace atomic absorption spectrometry (GFAAS). Two preparation procedures for urine give As recoveries close to
100% by HGAAS: a) dry ashing at 420°C with Mg(NO3)2 on a hot plate, and b) microwave oven decomposition with (NH4)2S2O8. For blood samples, As recoveries by HGAAS range between 95 and 108% for all species when using dry ashing after a pretreatment
of samples with HNO3 and H2O2 in a microwave oven. Wet digestion with (NH4)2S2O8 in a microwave oven gives recoveries very near 100% for As
inorg.
and MMA. For other As species in spiked blood samples, recoveries of less than 20% As are found. Precision and detection
limits obtained by both techniques are evaluated as well. For arsenic concentrations of 20 μg dm−3 or more in blood and urine, a chemical modifier is recommended for GFAAS analysis; it may or may not be proceeded by a mineralization
step. For low As levels encountered in the unexposed population, the HGAAS technique provides reliable results only if a very
complete mineralization procedure is used. 相似文献
4.
The flow of a vapor through a porous ceramic membrane is investigated. The membrane consists of several layers and is asymmetric with respect to the flow direction. The flow process is modeled accounting for capillary condensation, for the capillary pressure at liquid menisci, and for the temperature difference between the upstream and the downstream side of the membrane due to the Joule-Thomson effect, which induces a transfer of heat in downstream direction. Condensation may occur in various parts of the membrane. Condensation has a large influence on the mass flux through the membrane. The mass flux in one flow direction through the membrane may be a few times larger than the mass flux in the other flow direction. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
The sequential extraction test, known as a BCR procedure, was used to assess a leachability of heavy metals (Zn, Cd, Pb, Cu) from the metallo-organic sorbent—iron humate—loaded with these metals. The sequential test allowed to discriminate between various fractions of heavy metals, namely the acid-extractable fraction, the fraction bound to Fe oxides, and the fraction bound to organic matter. It was proven that the heavy metals are bound mainly to Fe oxides and organic matter, and thus they may be relatively hardly liberated into the environment. The BCR sequential extraction test exhibited a very good repeatability, when it was applied to the loaded sorbent—relative standard deviations were typically lower than 10%. 相似文献
6.
Skrivanová K Skorpíková J Svihálek J Mornstein V Janisch R 《Journal of photochemistry and photobiology. B, Biology》2006,85(2):150-154
The present study investigates the photochemical properties of a potential photosensitiser, indocyanine green (ICG), in an in vitro HeLa cell system. Cell proliferation was studied after a combined effect of ICG, at a concentration range of 24-94 microM, and therapeutic laser irradiation at several different energy densities. In addition, ICG cytotoxicity was evaluated in HeLa cells and V79 Chinese hamster by the MTT assay. Phototoxicity was evaluated at 1, 24, and 48 h after irradiation. No phototoxic effect was detected 1h after irradiation. The maximum phototoxic effect of ICG on HeLa cells was detected for an ICG concentration of 94 microM, a laser output of 360 mW, and an energy density of 99 J/cm(2) at 24h after irradiation. Potentiation of the ICG phototoxic effect was achieved by adding 20 microM H(2)O(2), which was a non-toxic concentration for HeLa cells in this experimental design. At 48 h after laser irradiation a statistically significant difference was found between the toxicity of ICG plus peroxide, as compared to ICG alone. The addition of H(2)O(2) at a concentration of 20 microM caused a significant increase in phototoxicity of ICG for HeLa cells. Our results confirm that ICG could be a perspective agent for use in photodynamic therapy and that its phototoxic effect can be potentiated by addition of an oxidative agent. 相似文献
7.
Alena Reznickova Zdenka Kolska Vladimir Hnatowicz Vaclav Svorcik 《Journal of nanoparticle research》2011,13(7):2929-2938
Properties of pristine, plasma modified, and etched (by water and methanol) polytetrafluoroethylene (PTFE) were studied. Gold
nanolayers sputtered on this modified PTFE have been also investigated. Contact angle, measured by goniometry, was studied
as a function of plasma exposure and post-exposure aging times. Degradation of polymer chains was examined by etching of plasma
modified PTFE in water or methanol. The amount of ablated and etched layer was measured by gravimetry. In the next step the
pristine, plasma modified, and etched PTFE was sputtered with gold. Changes in surface morphology were observed using atomic
force microscopy. Chemical structure of modified polymers was characterized by X-ray photoelectron spectroscopy (XPS). Surface
chemistry of the samples was investigated by electrokinetic analysis. Sheet resistance of the gold layers was measured by
two-point technique. The contact angle of the plasma modified PTFE decreases with increasing exposure time. The PTFE amount,
ablated by the plasma treatment, increases with the plasma exposure time. XPS measurements proved that during the plasma treatment
the PTFE macromolecular chains are degraded and oxidized and new –C–O–C–, –C=O, and –O–C=O groups are created in modified
surface layer. Surface of the plasma modified PTFE is weakly soluble in methanol and intensively soluble in water. Zeta potential
and XPS shown dramatic changes in PTFE surface chemistry after the plasma exposure, water etching, and gold deposition. When
continuous gold layer is formed a rapid decrease of the sheet resistance of the gold layer is observed. 相似文献
8.
9.
Pinkas J Reichlova V Zboril R Moravec Z Bezdicka P Matejkova J 《Ultrasonics sonochemistry》2008,15(3):257-264
Amorphous nanoscopic iron(III) oxide with interesting magnetic properties was prepared by sonolysis of Fe(acac)(3) under Ar in tetraglyme with a small amount of added water. The organics content and the surface area of the Fe(2)O(3) nanoparticles can be controlled with an amount of water in the reaction mixture and it increases from 48 m(2)g(-1) for dry solvent up to 260 m(2)g(-1) when wet Ar is employed. For further monitoring of the particle size and morphology and for the study of the surface, magnetic and thermal properties, the sample with 2 vol.% of H(2)O was chosen. SEM showed nanoscopic composite particles of a uniform size distribution and nearly spherical shapes with an estimated diameter of 20 nm. Such composites are built from amorphous iron(III) oxide nanoparticles (3 nm) embedded in an acetate matrix as proved by TEM and IR spectroscopy. Temperature-dependent M?ssbauer spectra demonstrate a very narrow magnetic transition with an unusually low transition temperature around 25K reflecting the system of magnetically non-interacting ultrasmall particles with a narrow size distribution. The in-field (5T) M?ssbauer spectrum recorded at 5K shows a minimum change compared to the zero-field spectrum indicating an absence of the long-range magnetic ordering. The composite particles are thermally stable up to 150 degrees C, which is confirmed by DSC, TG, and by the constant surface area. At higher temperatures, acetate groups are removed from the particle surface, which is documented by the increased surface area and disappearance of their IR bands. 相似文献
10.
Skalnikova H Rehulka P Chmelik J Martinkova J Zilvarova M Gadher SJ Kovarova H 《Analytical and bioanalytical chemistry》2007,389(5):1639-1645
We describe an optimised protocol for application of isobaric tags for relative and absolute quantitation (iTRAQ) and tandem
mass spectrometry to obtain relative quantitative data from peptides derived from tryptic digestions of proteins fractionated
by using the 2D liquid-phase ProteomeLab™ PF 2D technique. This methodology is suitable for the quantitation of proteins from
a pool of co-eluting proteins which are often difficult to identify for the purpose of candidate protein selection for biologically
relevant qualitative/quantitative changes under experimental conditions or in disease states. iTRAQ quantitation also facilitates
the possibility of result to result comparison using other methodologies such as UV protein quantitation via the ProteomeLab™
PF 2D technique. The optimised protocol outlined here allows relative quantitation by MALDI-TOF/TOF mass spectrometry with
high sensitivity and without the need to perform 2D HPLC separation of labelled peptides. The overall outcome is the simplification
in the data complexity and the ease of use of the labelling protocol.
This study is dedicated to Dr. Josef Chmelik in memory of his contribution and constant inspiration. 相似文献