Search results for "13C"
showing 10 items of 194 documents
Helicobacter pylori - diagnostika izmantojot 13C urīnvielas elptestu un seroloģijas testu: rezultātu salīdzināšana
2017
Ievads. 2012.gada veiktajā pētījumā tika iegūti dati, ka Latvijā Helicobacter Pylori (HP) izplatība pieaugušo populācijā ir augstā līmenī – 79.21%. Prezentētajā pētījumā tika analizēta HP infekcijas izplatība saistībā ar sociāli-demogrāfiskiem faktoriem - dalībnieku izglītības līmeni, nodarbinātību, vidējiem ienākumiem, ģimenes stāvokli, smēķēšanas paradumiem Latvijas iedzīvotājiem. Pētījuma mērķis. HP testu, kuri veikti izmantojot 13C urīnvielas elptestu un seroloģijas testu Daudzcentru randomizēts pētījums kuņģa vēža izraisītās mirstības samazināšanai (GISTAR) pētījuma ietvarā, rezultātu salīdzināšana saistībā ar sociāli-demogrāfiskiem faktoriem. Materiāli un metodes. Darbs ir šķērsgriezu…
Contributions of autochthonous and allochthonous sources to dissolved organic matter in a large, shallow, eutrophic lake with a highly calcareous cat…
2013
We traced the origin of dissolved organic matter (DOM) in the large, shallow, eutrophic Lake Vortsjarv in Estonia. Allochthonous DOM (Al-DOM) had higher δ13C values than autochthonous DOM (Au-DOM). The δ13C of inflow DOM varied from −28.2‰ to −25.4‰ (mean −26.7‰) and in-lake DOM varied from −28.4‰ to −26.1‰ (mean −27.2‰). Low stable isotope (SI) signatures of Au-DOM were caused by relatively 13C-depleted values of its precursors (mainly phytoplankton) with mean δ13C of −28.9‰. SI signatures of dissolved inorganic carbon (DIC) in the inflows and in the lake were also relatively low (from −15.1‰ to −3.28‰). SI values of DOM were lower during the active growing season from May to September and…
δ pattern of dissolved inorganic carbon in a small granitic catchment: the Strengbach case study (Vosges mountains, France)
1999
Abstract The transfers and origins of dissolved inorganic carbon (DIC) were studied for a year in a soil–spring–stream system in the Strengbach catchment, Vosges mountains, France. This 80 ha experimental research basin is located on the eastern side of the mountains, at an altitude ranging from 883 to 1146 m.a.s.l. and is mainly covered by spruce (80%). Brown acid and podzolic soils developed on a granitic basement, and, as a result, the DIC originates solely from CO2 generated by oxidation of soil organic matter. The ( δ 13 C DIC ) in catchment waters is highly variable, from about −22‰ in the springs and piezometers to about −12‰ in the stream at the outlet of the catchment. In the sprin…
In the Shadows of a hypergraph: looking for associated primes of powers of squarefree monomial ideals
2018
The aim of this paper is to study the associated primes of powers of square-free monomial ideals. Each square-free monomial ideal corresponds uniquely to a finite simple hypergraph via the cover ideal construction, and vice versa. Let H be a finite simple hypergraph and J(H) the cover ideal of H. We define the shadows of hypergraph, H, described as a collection of smaller hypergraphs related to H under some conditions. We then investigate how the shadows of H preserve information about the associated primes of the powers of J(H). Finally, we apply our findings on shadows to study the persistence property of square-free monomial ideals and construct some examples exhibiting failure of contai…
Further orthometalated dinuclear palladium(iii) compounds with bridging N,S-donor ligands
2013
New dinuclear palladium(III) compounds of general formula Pd2[(C6H4)PPh2]2[N-S]2Cl2, N-S being 2-mercaptopyridinate, 3a; 2-mercapto-6-methylpyridinate, 3b; 2-quinolinethiolate, 3c; 2-mercaptopyrimidinate, 3d; 1-methyl-1H-imidazole-2-thiolate, 3e; 1-methyl-1H-benzimidazole-2-thiolate, 3f; 2-mercaptobenzothiazolate, 3g and 5-mercapto-1-methyltetrazolate, 3h have been obtained by oxidation with PhICl2 of the corresponding palladium(II) counterparts. The stability of the new compounds has been studied by (31)P NMR spectroscopy from 200 to 298 K. Compounds 3f-h were relatively stable until room temperature and they have been synthesized and characterized by (31)P, (1)H and (13)C NMR spectroscopy…
Herstellung und 13 C‐NMR‐Spektroskopie isomerer 1,4‐Heterophosphorinanium‐Salze
1978
Die quartaren Diallylphosphonium-Salze 1–8 werden mit Natronlauge, Natriumhyrogensulfid. Ammoniak oder prim. Aminen zu den 1,4-Oxa- (9–14), 1,4-Thia- (15–21) und 1,4-Azaphosphorinanium-Salzen (22–36) umgesetzt. Die Konformation bzw. Konfiguration der in den meisten Fallen als Isomerengemische anfallenden Salze 9–36 wird 1H- bzw. 13C-NMR-spektroskopisch untersucht. Eine Abhangigkeit von der geometrischen Anordnung sowohl der 4JPH- als auch der vicinalen3JPC-Kopplungskonstanten konnte bei diesen nicht gespannten 1,4-Diheterocylohexanen festgestellt werden. Synthesis and 13C NMR Spectra of Isomeric 1,4-Heterophosphorinanium Salts The phosphonium salts 1–8 react with aqueous sodium hydroxide, s…
(Table 1) Trace element/Ca ratios of Orbulina universa shells from late Neogene Mediterranean samples
2008
A Mediterranean composite sedimentary record was analyzed for Ba/Ca ratios on carbonate shells of Orbulina universa planktonic foraminifer (Ba/Ca)carb providing the opportunity to study and assess the extent of freshwater inputs on the basin and possible impacts on its dynamics during the Tortonian to Recent period. A number of scanning electron microscope analyses and auxiliary trace element measurements (Mn, Sr, and Mg), obtained from the same samples, exclude important diagenetic effects on the studied biogenic carbonates and corroborate the reliability of (Ba/Ca)carb ratios in foraminifera calcite as indicators of seawater source components during the studied interval. A long-term trend…
Stable isotopic composition of three foraminifera species in ODP Hole 160-963D
2020
Carbon-rich layers exist at both sides of the Mediterranean Sea sedimentary record and are called sapropels and organic rich layers (ORLs), respectively in the eastern and western basins. They have different levels of organic carbon accumulation and seafloor oxygen deprivation. The most recent sapropel and ORL deposition have a different timing, 10.8-6.1 and 14.5-9.0 ka respectively. Here we investigate oxygen isotopic records of three foraminifera species that occupy different habitats within the Sicily Channel water column since ~ 12.0 ka, thus in the sill between the eastern and western Mediterranean basins. These data are ice volume-corrected, to get information on water masses density …
Core oligosaccharide of Escherichia coli B—the structure required for bacteriophage T4 recognition
2015
Abstract The structure of Escherichia coli B strain PCM 1935 core oligosaccharide has been investigated by 1H and 13C NMR spectroscopy, MALDI-TOF MS and ESI MSn. It was concluded that the core oligosaccharide is a pentasaccharide with the following structure: ESI MS/MS analysis revealed that the glycine (a minor component) is linked to the →3,7)- l -α- d -Hepp-(1→ residue.
Sesquiterpenoids in subtribe Centaureinae (Cass.) Dumort (tribe Cardueae, Asteraceae): distribution, (13)C NMR spectral data and biological propertie…
2012
Asteraceae Bercht. & J. Presl is one of the biggest and most economically important plant families. The taxonomy and phylogeny of Asteraceae is rather complex and according to the latest and most reliable taxonomic classification of Panero & Funk, based on the analysis of nine chloroplast regions, the family is divided into 12 subfamilies and 35 tribes. One of the largest tribes of Asteraceae is Cardueae Cass. with four subtribes (Carlininae, Echinopinae, Carduinae and Centaureinae) and more than 2500 species. Susanna & Garcia-Jacas have organized the genera of Centaureinae (about 800 species) into seven informal groups, which recent molecular studies have confirmed: 1. Basal genera; 2. Vol…