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61.
Ruta Bariseviciute Justinas Ceponkus Valdas Sablinskas 《Central European Journal of Chemistry》2007,5(1):71-86
A new method is used for the separation of ethene secondary ozonide (SOZ) from the other products of ethene ozonization reaction.
The reaction was performed in the neat films of the reactants at 77 K. Ethene SOZ was separated from other products of the
reaction by vacuum distillation at 190–210 K and analyzed by means of the matrix isolation IR absorption spectroscopy. Spectroscopic
data from photolysis of the matrix isolated ozonide was used as an argument for assignment of the infrared spectral bands
either to ethene SOZ or to other products of the reaction. The spectra of ethene SOZ isolated in the Ar matrix were analyzed
by combining experimental results with the theoretical calculations performed at the MP2 6-311+G (3df, 3pd) level.
A new assignment of some experimental fundamental bands is proposed taking in to account the Fermi resonance between CH stretch
and the five membered ring vibrations. For the first time more than 30 weak infrared absorption bands were observed and assigned
to various combination vibrations and overtones. By using new spectral information concerning the overtones and the combination
bands it is concluded that the dissociation of unstable ethene SOZ involving breaking of any of the four CO bonds of the five
membered ring of ethene SOZ has low probability. Dissociation of the ring starts from breaking of the OO bond.
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62.
Kalnina I Zvagule T Gabruseva N Kirilova J Kurjane N Bruvere R Kesters A Kizane G Kirilovs G Meirovics I 《Journal of fluorescence》2007,17(6):633-638
ABM (3-aminobenzanthrrone derivative) developed at the Riga Technical University, Riga, Latvia) has been previously shown
as a potential probe for determination of the immune state of patients with different pathologies .The fist study (using probe
ABM) of peripheral blood mononuclear cells (PBMC) membranes of 97 Chernobyl clean-up workers from Latvia was conducted in
1997. Now we repeatedly examine the same (n = 54) individuals in dynamics. ABM spectral parameters in PBMC suspension, fluorescence
anisotropy and blood plasma albumin characteristics were recorded. In 1997 screening showed 5 different patterns of fluorescence
spectra, from which in 2007 we obtained only two. These patterns of spectra had never been previously seen in healthy individuals
or patients with tuberculosis, multiple sclerosis, rheumatoid arthritis, etc., examined by us. Patterns of ABM fluorescence
spectra are associated with membrane anisotropy and conformational changes of blood plasma albumin. We observed that in dynamics
1997–2007 the lipid compartment of the membrane became more fluid while the lipid-protein interface became more rigid. The
use of probe ANS and albumin auto-fluorescence allowed show conformational alterations in Chernobyl clean-up workers blood
plasma. It is necessary to note that all investigated parameters significantly differ in observed groups of patients. These
findings reinforce our understanding that that the cell membrane is a significant biological target of radiation. The role
of the membrane in the expression and course of cell damage after radiation exposure must be considered. So ten years dynamic
of PBMC membrane characteristics by ABM (spectral shift and anisotropy indexes) in Chernobyl clean-up workers reveal progressive
trend toward certain resemblance with those of chronic B-cell lymphoid leukemia. 相似文献
63.
R Mitrica I Dumitru LL Ruta AM Ofiteru IC Farcasanu 《Molecules (Basel, Switzerland)》2012,17(9):10355-10369
Green tea extracts (GTEs) as well as their main component, the polyphenol epigallocatechin gallate (EGCG), are known for their versatile antioxidant, antimicrobial, antitumoral or anti-inflammatory effects. In spite of the huge beneficial action, there is increasing evidence that under certain conditions green tea and its components can be detrimental to living organisms. Using Saccharomyces cerevisiae strains with various defects in the response to oxidative stress, we found that GTEs or EGCG act in synergy with visible light, exhibiting either deleterious or protective effects depending on the solvent employed. Similar synergistic effects could be observed under singlet oxygen-generating conditions, such as light exposure in the presence of photosensitizers or UV-A irradiation, therefore solvent variance may represent a powerful tool to modulate the preparation of green tea extracts, depending on the intended target. 相似文献
64.
Ruta J Rudaz S McCalley DV Veuthey JL Guillarme D 《Journal of chromatography. A》2010,1217(52):8230-8240
The aim of this study was to evaluate the importance of sample diluents to improve peak shapes in hydrophilic interaction liquid chromatography (HILIC), using low molecular weight (<1000 Da) analytes as well as peptides (with MW ranging between 1000 and 6000 Da) as model compounds. Various solvents were tested including water, acetonitrile, methanol, ethanol, propan-2-ol, dimethyl sulfoxide, and a number of combinations of them. For the analysis of small MW compounds, best peak shapes were obtained with sample dissolved in pure ACN but, IPA or a mixture of ACN/IPA (50:50, v/v) could represent a viable alternative in the case of solubility issues with pure ACN. For drug discovery applications, DMSO can be employed but in combination with at least 80% of ACN. For peptides analysis, acetonitrile, EtOH and IPA as sample diluents, provided similar chromatographic profiles, but pure EtOH or IPA were recommended to limit denaturation and samples solubility issues. Finally, whatever the nature of the compounds, it is recommended to add the lowest amount of water to the sample diluent, to maintain suitable peak shapes. 相似文献