Národní úložiště šedé literatury Nalezeno 14 záznamů.  1 - 10další  přejít na záznam: Hledání trvalo 0.01 vteřin. 
Metodika identifikace zdrojů znečišťování pomocí PMF pro strategické rozhodování při ochraně ovzduší – aktualizace 2023
Horník, Štěpán ; Sýkora, Jan ; Pokorná, Petra
Předkládaná metodika navrhuje využití spektroskopie nukleární magnetické rezonance (NMR) jako další analytické techniky pro identifikaci sloučenin v atmosférických aerosolech. Tato technika umožňuje výrazně zvýšit počet stanovovaných látek a tfm i případný počet markerů, které lze následně ve spojení s jinými metodami využít pro identifikaci zdrojů znečištění ovzduší pomocí pokročilé statistické analýzy. Mezi markery stanovované pomocí\nNMR spektroskopie náleží různé organické kyseliny, sulfonové kyseliny nebo sacharidy, které jsou charakteristické pro příslušné zdroje znečištění. Aktualizovaná metodika také představuje identifikaci biogenního zdroje, který předcházející metodiky nedokázaly stanovit.
NMR Aerosolomics Study of Water-Soluble Organic Compounds in Size-Resolved Particulate Matter
Horník, Štěpán ; Vodička, Petr ; Pokorná, Petra ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
Organic aerosols (OA) account for a significant fraction (10 – 90%) of atmospheric particulate matter (Hallquist et al., 2009). The composition of organic aerosols is very complex and is usually characterized by their water solubility. Water-soluble organic compounds (WSOC) constitute a large fraction of OA (10 – 80%) and consist of chemical species containing oxygenated functional groups such as hydroxyl, carboxyl, or carbonyl groups. NMR spectroscopy represents an alternative to commonly used techniques (gas chromatography-mass spectrometry, liquid chromatography-based techniques) for WSOC analysis. Our recently introduced method, called NMR aerosolomics, allows quantitative analysis of dozens of individual compounds from different aerosol samples. An important part of the characterization of aerosols is their classification by particle size. The analysis of individual compounds in the size-resolved fractions of the WSOC class has been performed only in a few studies that focus mainly on a particular subclass of compounds or use multiple analytical techniques.
Plný tet: Stáhnout plný textPDF
NMR Aerosolomics as a Tool to Distinguish Various Types of Aerosol Samples.
Horník, Štěpán ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
In the recent study, the summer and winter aerosol samples were analyzed using NMR aerosolomics approach. The samples were collected in Prague-Suchdol during summer 2008 and winter 2009 in two different particle size fractions - PM2.5 and PM 10. Around 50 compounds were identified in each aerosol spectrum owing to the comprehensive library. The profile of 86 identified compounds, which were identified in the samples altogether, served as an input data for statistical analysis. Multivariate statistical analysis clearly discriminates the two groups studied. Furthermore, it is possible to determine the most significant compounds.
Plný tet: SKMBT_C22019041212342 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
NMR Aerosolomics as a Tool to Distinguish Various Types of Aerosols.
Horník, Štěpán ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
Water-soluble organic compounds represent up to 80% of all organic compounds present in atmospheric aerosols. Unlike composition of inorganic compounds or volatile organic compounds, which seems to be well explored, the knowledge about WSOC composition is still rather limited. The most frequently used method for WSOC analysis is GC-MS, which is a very sensitive technique. However, the analysis of polar compounds via GC-MS requires derivatization and the quantification is extremely time consuming. The second widely used technique is ion chromatography (IC). Nowadays, IC is routinely used for analysis of specific groups of organic compounds such as carboxylic acids, amines or carbohydrates. On the other hand, there is NMR spectroscopy as a fully quantitative but rather insensitive method. NMR spectroscopy was for the purpose of aerosol chemistry employed only recently as this technique has undergone rapid development and sensitivity gain of late. So far, the use of NMR spectroscopy is mainly restricted to socalled Functional Group Analysis, of which main interest lies elsewhere than in identification of individual compounds.
Plný tet: SKMBT_C22019110512330 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
NMR Aerosolomics as a Tool to Distinguish Various Types of Aerosol Samples.
Horník, Štěpán ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
In the recent study, the summer and winter aerosol samples were analyzed using NMR aerosolomics approach. The samples were collected in Prague-Suchdol during summer 2008 and winter 2009 in two different particle size fractions - PM2.5 and PM 10. Around 50 compounds were identified in each aerosol spectrum owing to the comprehensive library. The profile of 86 identified compounds, which were identified in the samples altogether, served as an input data for statistical analysis. Multivariate statistical analysis clearly discriminates the two groups studied. Furthermore, it is possible to determine the most significant compounds.
Plný text: Stáhnout plný textPDF
Metabolomics Study of the Association between Pancreatic Cancer and Diabetes Mellitus.
Michálková, Lenka ; Horník, Štěpán ; Sýkora, Jan ; Habartová, L. ; Setnička, V.
In our study, 1H NMR metabolomics was employed to plasma samples of pancreatic cancer patients, individuals with long-term diabetes mellitus type 2 (lasting more than 5 years) and healthy controls. The NMR analyses were followed by establishing a statistical model based on principal component analysis and discriminant analysis. The aim was to discover differences between these groups and to define a potential biomarker panel. The statistical evaluation of metabolomics-based profiles provided high values of sensitivity and specificity. Subsequently, plasma samples of the risk group, specifically patients with recently diagnosed diabetes mellitus with a duration of <3 years (possible T3cDM), were analysed and the possibility of PC development was predicted. The achieved results showed strong potential of 1H NMR metabolomics to establish a biomarker panel that would facilitate the early diagnosis of PC and the possibility identify diabetic individuals, who are at risk of developing PC.
Plný tet: SKMBT_C22019041212340 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
NMR Aerosolomics as a Tool to Distinguish Various Types of Aerosol Samples.
Horník, Štěpán ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
In the recent study, the summer and winter aerosol samples were analyzed using NMR aerosolomics approach. The samples were collected in Prague-Suchdol during summer 2008 and winter 2009 in two different particle size fractions - PM2.5 and PM 10. Around 50 compounds were identified in each aerosol spectrum owing to the comprehensive library. The profile of 86 identified compounds, which were identified in the samples altogether, served as an input data for statistical analysis. Multivariate statistical analysis clearly discriminates the two groups studied. Furthermore, it is possible to determine the most significant compounds.
Plný tet: SKMBT_C22019041208492 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
NMR Metabolomics Study of the Association between Pancreatic Cancer and Diabetes Mellrtus.
Michálková, Lenka ; Horník, Štěpán ; Sýkora, Jan ; Habartová, L. ; Setnička, V.
In our study, 1H NMR metabolomics was employed to plasma samples of pancreatic cancer patients, individuals with long-term diabetes mellitus type 2 (lasting more than 5 years) and healthy controls. The NMR analyses were followed by establishing a statistical model based on principal component analysis and discriminant analysis. The aim was to discover differences between these groups and to define a potential biomarker panel. The statistical evaluation of metabolomics-based profiles provided high values of sensitivity and specificity. Subsequently, plasma samples of the risk group, specifically patients with recently diagnosed diabetes mellitus with a duration of <3 years (possible T3cDM), were analysed and the possibility of PC development was predicted. The achieved results showed strong potential of 1H NMR metabolomics to establish a biomarker panel that would facilitate the early diagnosis of PC and the possibility identify diabetic individuals, who are at risk of developing PC.
Plný tet: SKMBT_C22019041208491 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
NMR Aerosolomics: A Convenient Route to Organic Aerosol Analysis.
Horník, Štěpán ; Schwarz, Jaroslav ; Sýkora, Jan
Atmospheric aerosols are a small but very important part of the Earth’s atmosphere. The proportion of inorganic and organic compounds in aerosol particles seems to be equal on average. While the inorganic composition of aerosols is well explored, knowledge about the organic part is still very limited. It is well known that the major part of organic aerosol compounds is represented by polar, water-soluble organic compounds (WSOC). So far GC-MS is the most frequently used method for WSOC analysis. GC-MS is a very sensitive technique, furthermore, it exploits huge spectra libraries accumulated over decades. Therefore, its role in the determination of aerosol composition is indisputable. Primarily owing to GC-MS, about 150 organic compounds have been identified in aerosol particles. NMR spectroscopy for the purpose of aerosol chemistry was discovered only recently as it is rather insensitive method. Nevertheless, NMR has undergone rapid development and sensitivity gain of late. Moreover, it is fully quantitative method and no sample derivatization is needed. So far, the use of NMR spectroscopy has been limited to so called Functional group analysis. In this analysis the whole NMR spectrum is divided into parts and subsequently integrated according to functional groups.
Plný tet: SKMBT_C22018110212472 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
NMR Aerosolomics: A Convenient Route to Organic Aerosol Analysis.
Horník, Štěpán ; Schwarz, Jaroslav ; Sýkora, Jan
Both real atmospheric and model samples (from diesel combustion engines) have been analysed by the method. Special treatment of the real atmospheric samples led to the identification of at least 40 compounds in each analysed sample. Variations in the composition of different group fractions from the individual samples will be discussed in this work along with diesel combustion markers identification.
Plný text: Stáhnout plný textPDF

Národní úložiště šedé literatury : Nalezeno 14 záznamů.   1 - 10další  přejít na záznam:
Chcete být upozorněni, pokud se objeví nové záznamy odpovídající tomuto dotazu?
Přihlásit se k odběru RSS.