Search results for " nitrate"

Exploring Zinc Apatites through Different Synthesis Routes

2013

nclusion of zinc in apatites is not completely understood due to complexes in solution preventing the incorporation or the inclusion of defects. Some work has shown zinc addition by alternative synthesis routes, but the level of incorporation has not been reassessed. This work uses a newly developed approach whereby zinc is included in an amorphous phase and subsequently crystallized. Different phosphate reactants (ammonium, sodium or potassium phosphates) were mixed together with calcium salts (calcium nitrate or calcium acetate) and the pH level adjusted (with ammonia or KOH) to investigate the ease of forming an amorphous phase and the inclusion of zinc. X-ray diffraction revealed that a…

[Aquabis(nitrato-κO)copper(II)]-μ-{bis[5-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl]selenide}-[diaqua(nitrato-κO)copper(II)] nitrate monohydrate

2012

In the title binuclear complex, [Cu2(NO3)3(C18H16N6Se)(H2O)3]NO3·H2O, the Cu(II) ions are penta-coordinated in a tetra-gonal-pyramidal geometry. In both cases, the equatorial planes are formed by a chelating pyrazole-pyridine group, a water mol-ecule and a nitrate O atom, whereas the apical positions are occupied by a water mol-ecule for one Cu(II) ion and a nitrate O atom for the other. The organic selenide ligand adopts a trans configuration with respect to the C-Se-C plane. Numerous inter-molecular O-H⋯O and N-H⋯O hydrogen bonds between the coordinating and lattice water mol-ecules, nitrate anions and pyrazole groups are observed. π-π stacking inter-actions between the pyridine rings [av…

[Di-aqua-sesqui(nitrato-κO)hemi(perchlorato-κO)copper(II)]-μ-{bis-[5-methyl-3-(pyridin-2-yl)-1H-pyrazol-4-yl] selenide}-[tri-aqua-(perchlorato-κO)cop…

2013

In the binuclear title complex, [Cu2(ClO4)1.5(NO3)1.5(C18H16N6Se)(H2O)5]NO3·H2O, both Cu(II) ions are hexa-coordinated by O and N atoms, thus forming axially elongated CuO4N2 octa-hedra. The equatorial plane of each octa-hedron is formed by one chelating pyrazole-pyridine fragment of the organic ligand and two water mol-ecules. The axial positions in one octa-hedron are occupied by a water mol-ecule and a monodentately coordinated perchlorate anion, while those in the other are occupied by a nitrate anion and a disordered perchlorate/nitrate anion with equal site occupancy. The pyrazole-pyridine units of the organic selenide are trans-oriented to each other with a C-Se-C angle of 96.01 (14)…

Apparent Molar Volumes of Calcium Nitrate in 1-Propanol + Water at 298.15 K

1999

The densities of 1-propanol + water + calcium nitrate mixtures have been measured with an oscillating-tube densimeter over a large range of concentrations of the salt and 1-propanol, at 298.15 K. From these densities, apparent molar volumes of calcium nitrate in 1-propanol + water mixtures have been calculated, and partial molar volumes at infinite dilution have been evaluated.

Potential of interactive multiobjective optimization in supporting the design of a groundwater biodenitrification process

2019

The design of water treatment plants requires simultaneous analysis of technical, economic and environmental aspects, identified by multiple conflicting objectives. We demonstrated the advantages of an interactive multiobjective optimization (MOO) method over a posteriori methods in an unexplored field, namely the design of a biological treatment plant for drinking water production, that tackles the process drawbacks, contrarily to what happens in a traditional volumetric-load-driven design procedure. Specifically, we consider a groundwater denitrification biofilter, simulated by the Activated Sludge Model modified with two-stage denitrification kinetics. Three objectives were defined (nitr…

2009

Abstract. The emission of nitric oxide (NO) by soils (SNOx) is an important source of oxides of nitrogen (NOx=NO+NO2) in the troposphere, with estimates ranging from 4 to 21 Tg of nitrogen per year. Previous studies have examined the influence of SNOx on ozone (O3) chemistry. We employ the ECHAM5/MESSy atmospheric chemistry model (EMAC) to go further in the reaction chain and investigate the influence of SNOx on lower tropospheric NOx, O3, peroxyacetyl nitrate (PAN), nitric acid (HNO3), the hydroxyl radical (OH) and the lifetime of methane (τCH4). We show that SNOx is responsible for a significant contribution to the NOx mixing ratio in many regions, especially in the tropics. Furthermore, …

Product Quantum Yields for the 350 nm Photodecomposition of Pyruvic Acid in Air

1992

Quantum yields for the products CH3CHO, CO2 and CH3COOH in the 350 nm photodecomposition of pyruvic acid are 0.48 ± 0.01, 1.27 ± 0.18 and 0.14, respectively, as measured in air at atmospheric pressure. In the presence of NO2 the quantum yield for CH3CHO was reduced to 0.30 ± 0.04 and peroxyacetyl nitrate was formed with a quantum yield of 0.15 ± 0.02. This is taken to indicate the formation of acetyl radicals in one of the primary processes.

the role of mitochondrial aldehyde dehydrognase (ALDH-2) for bioactivation of organic nitrates: “Proof of concept” through investigations in ALDH-2 k…

2006

Simulataneous application of charge coupled device array-detected Raman spectroscopy and differential scanning calorimetry to in situ investigation o…

1992

The combination of differential scanning calorimetry (DSC) with charge coupled device (CCD) array-detected Raman spectroscopy for the in situ investigation of phase transition is illustrated using ammonium nitrate as an example. This method aids unambiguous characterization of different phases by providing a simultaneous probe of thermodynamic and vibrational data. The availability of real-time vibrational data, including both the internal and external mode regions, is unique to array-detected Raman spectroscopy. The intensity changes of the symmetric stretching mode ν1 of the nitrate ions and the lattice vibrations, that accompany the phase transition IV → II of ammonium nitrate, are ratio…

Transition paths between phases IV, III and II of ammonium nitrate predicted from X-ray powder diffractometer and differential scanning calorimeter d…

1994

Abstract Ammonium nitrate solid phase transition paths between phases IV, III and II were explained and predicted on the basis of X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) data by applying partial least-squares regression (PLS) and principal component analysis (PCA). The samples were clustered according to their different transition paths with the PLS and PCA models, and the transition paths were predicted with PLS component clusters. The best PLS clusters were formed by a few first components. Prediction of the transition path with the PLS clusters made a semiquantitative prediction of the transition energy possible. In PCA, principal components 6 and 11, w…