Search results for "Nitrogen"
showing 10 items of 1200 documents
Polycondensed nitrogen heterocycles. X. 5,6,7,8-Tetrahydropyrrolo[1,2-e][1,5]benzodiazocin-7-ones. A new ring system
1981
The synthesis of a new heterocyclic ring system is described. Condensation of 1,4-diketones 1a,b with β-alanine gave the substituted propionic acids 2a,b which upon reduction with palladium on charcoal afforded compounds 3a,b. Title compounds 4a,b were obtained by refluxing 3a,b in toluene with p-toluenesulphonic acid as catalyst.
ChemInform Abstract: Polycondensed Nitrogen Heterocycles. Part 24. Pyrrolo(3,4-c) isoquinolinone by Thermal Rearrangement of a Pyrrolylbenzotriazinon…
2010
Rearrangement under acidic conditions of the pyrrolylbenzotriazinone 7 afforded the pyrrolylbenzamides 10 and 11. By thermal rearrangement instead, the first fully aromatic derivative of the pyrrolo[3,4-c]isoquinoline ring system 9 was obtained.
Halogen bond preferences of thiocyanate ligand coordinated to Ru(II) via sulphur atom
2017
Halogen bonding between [Ru(bpy)(CO)2(S-SCN)2] (bpy = 2,2’-bipyridine), I2 was studied by co-crystallising the metal compound and diiodine from dichloromethane. The only observed crystalline product was found to be [Ru(bpy)(CO)2(S-SCN)2]⋅I2 with only one NCS⋅⋅⋅I2 halogen bond between I2 and the metal coordinated S atom of one of the thiocyanate ligand. The dangling nitrogen atoms were not involved in halogen bonding. However, computational analysis suggests that there are no major energetic differences between the NCS⋅⋅⋅I2 and SCN⋅⋅⋅I2 bonding modes. The reason for the observed NCS⋅⋅⋅I2 mode lies most probably in the more favourable packing effects rather than energetic preferences between …
Variability in inorganic and organic nitrogen uptake associated with riverine nutrient input in the Gulf of Riga, Baltic Sea
2001
Concentrations and rates of uptake of dissolved organic nitrogen (DON, free amino acids, and urea) and inorganic nitrogen (DIN, nitrate, and ammonium) were measured along two transects in the Gulf of Riga, a sub-basin of the Baltic Sea, during May and July 1996. Concentrations of total dissolved nitrogen (TDN) were 23±3 μg-at N 1−1 in the northern region (mouth) and 41±5 μg-at N 1−1 in the southern region (head) of the Gulf. Rates of nitrogen uptake, determined with15N-labeled substrates, reflected differences in TDN concentration between the regions. In May, uptake of DIN+DON measured 0.17 and 0.43 μg-at N 1−1 h−1 in the northern and southern parts of the Gulf, respectively. In July, DIN+D…
Abundance and activity of nitrate reducers in an arable soil are more affected by temporal variation and soil depth than by elevated atmospheric [CO2]
2011
Elevated atmospheric carbon dioxide concentrations ([CO2]) might change the abundance and the function of soil microorganisms in the depth profile of agricultural soils by plant-mediated reactions. The seasonal pattern of abundance and activity of nitrate-reducing bacteria was studied in a Mini-FACE experiment planted with oilseed rape (Brassica napus). Three depths (0–10, 10–20 and 20–30 cm) were sampled. Analyses of the abundances of total (16S rRNA gene) and nitrate-reducing bacteria (narG, napA) revealed strong influences of sampling date and depth, but no [CO2] effects. Abundance and activity of nitrate reducers were higher in the top soil layer and decreased with depth but were not re…
ChemInform Abstract: Polycondensed Nitrogen Heterocycles. Part 17. Isoxazolo(4,3-d)pyrazolo-(3,4-f)(1,2,3)triazepine. A New Ring System.
1988
The title compounds were prepared by nitration of compounds 2, reduction of the dinitro derivatives 4 and diazotization of the diamino derivatives 6 followed by an intramolecular coupling reaction. Compound 4a showed good activity against Salmonella cholerasuis and Clostridium perfringens bacteria.
Seasonal variation of average phytoplankton concentration in the Kattegat—a periodical point model
2003
Abstract Seasonal variations in primary production, phytoplankton biomass, chlorophyll-a, dissolved inorganic phosphorus and nitrogen concentrations in the upper 10 m of the Kattegat were analysed by means of monitoring data from 1993–1997. Spatial optimal analysis, based on a stochastic model, was used to reconstruct weekly constituent fields onto a spatial grid. The reconstructed fields were spatially integrated, resulting in a relatively smooth seasonal variability of the average variables. A simple dynamical model, set up as a periodical boundary problem, is suggested for the average phytoplankton concentration, dissolved inorganic nitrogen and entrainment depth as state variables. The …
Evaluation of Hybrid Models to Estimate Chlorophyll and Nitrogen Content of Maize Crops in the Framework of the Future CHIME Mission
2022
In the next few years, the new Copernicus Hyperspectral Imaging Mission (CHIME) is foreseen to be launched by the European Space Agency (ESA). This mission will provide an unprecedented amount of hyperspectral data, enabling new research possibilities within several fields of natural resources, including the “agriculture and food security” domain. In order to efficiently exploit this upcoming hyperspectral data stream, new processing methods and techniques need to be studied and implemented. In this work, the hybrid approach (HYB) and its variant, featuring sampling dimensionality reduction through active learning heuristics (HAL), were applied to CHIME-like data to evaluate the…
Interactive Effects of Genotype and Molybdenum Supply on Yield and Overall Fruit Quality of Tomato
2019
Molybdenum (Mo) is an essential trace element for plant growth, development, and production. However, there is little known about the function and effects of molybdenum in tomato plants. The present study assessed the influences of different Mo concentrations on four tomato F1 hybrids (“Bybal” F1, “Tyty” F1, “Paride” F1, and “Ornela” F1) grown using a soilless system with different Mo levels [0.0, 0.5 (standard NS), 2.0, and 4.0 μmol L−1, respectively]. The crop yield, plant vigor, fruit skin color, TA, fruit water content as well as the accumulation of SSC, and some antioxidant compounds such as lycopene, polyphenols and ascorbic acid were evaluated. The minerals concentration, including n…
Synthesis, characterization and magnetic study of two new octahedral iron(III) complexes with pendant zwitterionic Schiff bases
2016
Two Schiff bases, HL1 [2-((3-(dimethylamino)propylimino)methyl)-5-bromophenol] and HL2 [2-((2-(diethylamino)ethylimino)methyl)-6-methoxyphenol], have been employed to prepare two new octahedral iron(III) complexes, [Fe(HL1)2(N3)2]ClO4·2H2O (1) and [Fe(HL2)2(NCS)2]ClO4·H2O (2). Both complexes are characterized by spectral and elemental analyses. Single crystal X-ray diffraction studies confirm their structures. In both complexes, Schiff bases are trapped in their zwitterionic forms and coordinated to iron(III) only through the imine nitrogen and phenoxo oxygen, i.e., they behave as bi-dentate ligands, keeping the remaining potential donor sites pendant. The measurement of χM vs. T for both c…