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Comprehensive evaluation of biogenic amines and related drugs’ antiradical activity using reactive 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical

100%
Sârbu C., Casoni D.
Open Chemistry
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2013
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vol. 11
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issue 5
679-688
EN
A comprehensive study of biogenic amines and related drugs as free radical scavengers and potential antioxidants was carried out using the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH·). The results of the effect of test duration and the relative concentration on the ability of the compounds to scavenge the DPPH· were investigated and discussed. The antiradical activity of amines was compared with the activity of some reference antioxidants (phenols, phenolic acids, flavonols and other antioxidants). Some particular insights related to the mechanism of reactivity toward the DPPH· were investigated by carrying out kinetic studies in methanol for different relative concentrations. According to the obtained results, catecholamines and especially their related drugs (D-dopa, adrenalone, S-(−)-carbidopa and isoprenaline) showed a fast reactivity towards DPPH· and the highest antiradical activity which increased in a concentration-dependent manner. Moreover, catecholamines proved to be more powerful scavengers than ascorbic and caffeic acids even at low concentrations while their related drugs (D-dopa, adrenalone and S-(−)-carbidopa) showed higher antiradical activity than gallic acid for all of the investigated concentrations. [...]
2
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Application of linear discriminant analysis to the study of dew chemistry on the basis of samples collected in Poland (2004–2005)

61%
Klimaszewska K., Sârbu C., Polkowska Ż., Lech D., Pasławski P., Małek S., Namieśnik J.
Open Chemistry
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2009
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vol. 7
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issue 1
20-30
EN
This paper presents the results of determination of selected characteristics (anions, cations, formaldehyde, hydrogen peroxide, phenols, TC, TIC, TOC and metals) in dew samples collected in six different sites in Poland. The influence of local parameters (e.g. wind speed, humidity) was investigated. Discriminant analysis was applied to the study of several dew samples collected from different sampling sites covering six agglomerations in Poland. Discriminant function analysis was used not only for classifying samples into different groups with a better than chance accuracy, but also for detecting the most important variables that discern between the groups of samples considered. In this way it was possible to identify which ions or other physicochemical features are responsible for the similarities or differences observed between different groups of dew samples. A good agreement with their origin and location was observed. It is interesting to note that the classification of all samples was dominated by pH, wind direction, pressure and temperature with a significant contribution of Na+ and Cl− ions. [...]
3
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A comparative study concerning chromatographic retention and computed partition coefficients of some precursors of peraza crown ethers

61%
Onişor C., Blăniţă G., Coroş M., Bucşa M., Vlassa M., Sârbu C.
Open Chemistry
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2010
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vol. 8
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issue 6
1203-1209
EN
Retention indices for some precursors of peraza crown ethers were determined by reversed phase high-performance thin layer chromatography on RP-18 plates with methanol-water in different volume proportions as mobile phase. The Log P values for the same compounds were calculated using different computer programs: SciQSAR, SciLogP, Chem3D Ultra 8.0, XLOGP (based on atom contributions), Chemaxon and KOWWIN (based on atom/fragment contributions), cLogP (based on fragmental contributions), ALOGPS and IAlogP (based on atom-type electrotopological-state indices and neural network modeling). A comparative study concerning lipophilic parameters (RM0, b and ϕ0) and computed partition coefficients has been developed. Taking into account the correlation coefficients between determined and calculated Log P values, it seems that RM0 and b are less suitable than ϕ0 for estimating lipophilicity of the compounds investigated, and cLogP and ALOGPS provide the best correlations with experimental values.
4
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Rime samples characterization and comparison using classical and fuzzy principal components analysis

61%
Klimaszewska K., Sârbu C., Polkowska Ż., Błaś M., Sobik M., Namieśnik J.
Open Chemistry
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2008
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vol. 6
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issue 2
208-215
EN
The main objective of this paper is to introduce principal component analysis and two robust fuzzy principal component algorithms as useful tools in characterizing and comparing rime samples collected in different locations in Poland (2004–2007). The efficiency of the applied procedures was illustrated on a data set containing 108 rime samples and concentration of anions, cations, HCHO, as well as pH and conductivity. The fuzzy principal component algorithms achieved better results mainly because they are more compressible than classical PCA and very robust to outliers. For example, a three component model, fuzzy principal component analysis-first component (FPCA-1) accounts for 62.37% of the total variance and fuzzy principal component analysis-orthogonal (FPCA-o) 90.11%; PCA accounts only for 58.30%. The first two principal components explain 51.41% of the total variance in the case of FPCA-1 and 79.59% in the case of FPCA-o as compared to only 47.55% for PCA. As a direct consequence, PCA showed only a partial differentiation of rime samples onto the plane or in the space described by different combination of two or three principal components, whereas a much sharper differentiation of the samples, regarding their origin and location, is observed when FPCAs are applied. [...]
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