Search results for "Nitrogen"
showing 10 items of 1200 documents
Abundance of narG , nirS , nirK , and nosZ Genes of Denitrifying Bacteria during Primary Successions of a Glacier Foreland
2006
ABSTRACT Quantitative PCR of denitrification genes encoding the nitrate, nitrite, and nitrous oxide reductases was used to study denitrifiers across a glacier foreland. Environmental samples collected at different distances from a receding glacier contained amounts of 16S rRNA target molecules ranging from 4.9 × 10 5 to 8.9 × 10 5 copies per nanogram of DNA but smaller amounts of narG , nirK , and nosZ target molecules. Thus, numbers of narG , nirK , nirS , and nosZ copies per nanogram of DNA ranged from 2.1 × 10 3 to 2.6 × 10 4 , 7.4 × 10 2 to 1.4 × 10 3 , 2.5 × 10 2 to 6.4 × 10 3 , and 1.2 × 10 3 to 5.5 × 10 3 , respectively. The densities of 16S rRNA genes per gram of soil increased with…
Carbon and nitrogen stable isotope ratios of soils and grasses as indicators of soil characteristics and biological taxa
2019
Abstract The use of stable isotope techniques can assist in understanding interactions of plants with various abiotic and biotic processes. In the research, we focused on carbon (C) and nitrogen (N) isotopes because they are the most important resources influencing plant function and the biogeochemical cycles. The 13C/12C and 15N/14N ratios in plants and in soils and the relationships between these ratios and biological and environmental factors of widely distributed native C3 plants (couch grass, plantain and yarrow) collected from two sites in St. Petersburg, Russia were studied. The soil characteristics of the sites were rather different. This had a significant effect on the isotope rati…
XAFS study of gadolinium and samarium bisporphyrinate complexes.
2001
The comparative X-ray absorption spectroscopy study of gadolinium and samarium bisporphyrinate complexes represented by the formulas Gd(III)H(oep)(tpp), Gd(III)(oep)(2), Gd(III)H(tpp)(2) and Sm(III)H(oep)(tpp), Sm(III)(oep)(2), Sm(III)H(tpp)(2) is reported. The XAFS spectra are recorded on the LURE-DCI storage ring (Orsay, France) in transmission mode on the microcrystalline samples at the Gd and Sm L(3) edges. The local environment for Ln(3+) ions has been reconstructed applying one-shell and two-shell XAFS analysis procedures. The protonated and nonprotonated bisporphyrinate complexes present different XAFS features. After our analysis on the title derivatives, the gadolinium ion (at 80 K…
Characterization of particle morphology of biochanin A molecularly imprinted polymers and their properties as a potential sorbent for solid-phase ext…
2014
Abstract Molecularly imprinted polymers (MIPs) with biochanin A as a template were obtained using a bulk polymerization with non-covalent imprinting approach. The polymers were prepared in acetonitrile as porogen, using ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The synthesis, with an application of 1′,1′-azobis(cyclohexanecarbonitrile) (ACHN) as an initiator, has been performed thermally. During the synthesis process the effect of different functional monomers such as methacrylic acid (MAA), acrylamide (AA) and 4-vinylpyridine (4-VP) was investigated. The application of nitrogen sorption porosimetry, scanning electron microscopy (SEM), and Fourier transform infrared spec…
Root uptake, storage and remobilisation of autumn applied nitrogen to kiwifruit (Actinidia deliciosa) vines
2000
L'absorption racinaire, la subdivision, la conservation, et la redistribution de l'azote au niveau des racines ont ete etudiees sur des jeunes plantes de kiwi cv « Hayward », portant des fruits et cultives en pots. Deux rations de nitrate d'ammonium enrichi en 15 N [3,3 g (LN) et 10,0 g (HN) N par plante] ont ete distribuees 1 mois avant la recolte des fruits. Les fruits de kiwi ont absorbe 44-68 % du 1 5 N fourni a l'automne, qui a ete stocke principalement dans le systeme racinaire (61 %). Le 15 N a represente 22 et 36 % respectivement de l'azote total contenu dans les fruits des plantes LN et HN. Les feuilles ont retenu la plus grande partie de l'azote marque au cours de la senescence et…
Mapping landscape canopy nitrogen content from space using PRISMA data
2021
Abstract Satellite imaging spectroscopy for terrestrial applications is reaching maturity with recently launched and upcoming science-driven missions, e.g. PRecursore IperSpettrale della Missione Applicativa (PRISMA) and Environmental Mapping and Analysis Program (EnMAP), respectively. Moreover, the high-priority mission candidate Copernicus Hyperspectral Imaging Mission for the Environment (CHIME) is expected to globally provide routine hyperspectral observations to support new and enhanced services for, among others, sustainable agricultural and biodiversity management. Thanks to the provision of contiguous visible-to-shortwave infrared spectral data, hyperspectral missions open enhanced …
Ferrocenylbis(ylene) phosphoranes
1997
The ferrocenylbis(methylene)phosphorane Fc-P(=CTms 2 ) 2 ( 1 ) (Fc = −C 5 H 4 FeC 5 H 5 ) can be synthesized starting from ferrocenyldichlorophosphane FcPCl 2 or ferrocenyldilithiophosphane FcPLl 2 . The X-ray structure of ( 1 ) shows some unusual structural features, which indicate considerable electronic interaction of the ferrocenyl group and the σ 3 λ 5 -phosphorane unit. As a consequence of this interaction, the rotational barrier of the methylene bonds is extraordinary low. Therefore, in contrast to other bis(methylene)phosphoranes, the endo - and exo -Tms groups are indistinguishable on the NMR time scale even at −100°C. The analogous ferrocenylbis(imino)phosphorane Fc-P(=NTms) 2 ( 9…
The Use of 15N NMR for the Understanding of Nitrogen Physisorption.
1994
Abstract Nitrogen adsorption at liquid nitrogen temperature, 77K, is universally employed to determine pore dimensions. The nature of nitrogen physisorbed within the micropores of ZSM-5 zeolite was studied by in situ15N NMR as it depends on the partial pressure of the nitrogen and the temperature above and below 77K. An increase in the volume of adsorption of nitrogen at 77K occurs at a relative pressure of ~0.18 for this zeolite. The nature of the nitrogen was studied below and above this increase in nitrogen adsorption. We find that two states (phases) of nitrogen are evident. We conclude that two phases can be present but that a solid phase of nitrogen is not evident even as the temperat…
Exposure assessment of fruits contaminated with pesticide residues from Valencia, 2001– 03
2006
A total of 634 samples of oranges, tangerines, peaches, nectarines, khakis and watermelons were collected from an Agricultural Valencia Community Cooperative during the May 2001 to April 2003 campaigns and they were analysed for 15 pesticides among those recommended for pest treatment. A conventional multiresidue analytical procedure based on ethyl acetate extraction was used followed by gas chromatography coupled to a nitrogen phosphorus detector for routine analysis; and mass spectrometry was performed for confirmation. Recovery studies with spiked samples at 0.5 mg kg-1 for each pesticide ranged from 52% for acephate to 87% for fenthion with a standard deviation20%. Limits of quantificat…
Bendamustine with or without rituximab in the treatment of relapsed chronic lymphocytic leukaemia: an Italian retrospective study.
2011
To retrospectively assess the efficacy of bendamustine alone and with rituximab (R-B), 109 patients with relapsed chronic lymphocytic leukaemia (CLL) were enrolled in 24 Italian centres. The median age was 66 years (range 39-85). Forty-three percent of patients had relapsed and 57% were resistant (median previous therapies = 3; range 1-8). Twenty-two patients received bendamustine alone and 87 patients received R-B (median B dosage: 100 mg/m(2) per day, range 90-130 mg/m(2) per day). The overall response rate was 69·6% (complete response 28·6%; partial response 41%), and was significantly higher in patients treated with R-B (P = 0·014) and in those responsive to the previous treatment (P=0·…