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The fatty acids of two composts of active sludge with palm tree waste were investigated by thermochemolysis coupled to gas chromatography-mass spectrometry. This method (tetramethylammonium hydroxide-pyrolysis-gas chromatography-mass spectrometry) allowed the direct determination of total fatty acids (analysed as fatty acid methyl esters: FAMEs) present in the organic matter of the samples without any separation procedures. Mixture A was 1/3 sludge+2/3 palm waste and mixture B was 1/2 sludge+1/2 palm waste. The level of FAMEs rose by 8.4–33.3% and 10.8–13.4% in mixtures A and B, respectively, after 6 months of co-composting. Branched FAMEs of bacterial origin (iC15:0) rose during the thermophilic phase, in mixture A theaC17:0/aC15:0 ratio increased during the co-composting process, also in mixture B theaC16:0/C16:0 ratio rose but only during the thermophilic phase. All the FAMEs identified showed a drop at the end of co-composting except for C18:0 and C16:0. The stabilisation phase was characterised by a significant rise in the length of the aliphatic chains; the carbon preference index thus increased at the end of the composting process, indicating that the final product was proportionally richer in fatty acids of plant origin. [ABSTRACT FROM PUBLISHER]

We report on the observation of orbital excitations in YVO3 by means of resonant inelastic x-ray scattering (RIXS) at energies across the vanadium L3 and oxygen K absorption edges. At the V L3 edge, we are able to resolve the full spectrum of orbital excitations up to 5 eV. In order to unravel the effect of superexchange interactions and the crystal field on the orbital excitations, we analyzed the energy and temperature dependence of the intra-t2g excitations at 0.1-0.2 eV in detail. While these results suggest a dominant influence of the crystal field, peak shifts of about 13-20 meV observed as a function of the transferred momentum q∥a reflect a finite dispersion of the orbital excitations. This is puzzling since theoretical models based on superexchange interactions predict a dispersion only for q ∥c. Furthermore, we demonstrate that RIXS at the O K edge is very sensitive to intersite excitations. At the O K edge, we observe excitations across the Mott-Hubbard gap and an additional feature at 0.4 eV, which we attribute to two-orbiton scattering, i.e., an exchange of orbitals between adjacent sites. Altogether, our results indicate that both superexchange interactions and the crystal field are important for a quantitative understanding of the orbital excitations in YVO3. [ABSTRACT FROM AUTHOR]

Compounds with intermediate-size transition metals such as Fe or Mn are close to the transition between charge-transfer systems and Mott-Hubbard systems. We study the optical conductivity σ(ω) of insulating layered LaSrFeO4 in the energy range 0.5-5.5 eV from 15 K to 250 K by the use of spectroscopic ellipsometry in combination with transmittance measurements. A multipeak structure is observed in both σa(ω) and σc(ω). The layered structure gives rise to a pronounced anisotropy, thereby offering a means to disentangle Mott-Hubbard and charge-transfer absorption bands. We find strong evidence that the lowest dipole-allowed excitation in LaSrFeO4 is of Mott-Hubbard type. This rather unexpected result can be attributed to Fe 3d-O 2p hybridization and in particular to the layered structure with the associated splitting of the eg level. In general, Mott-Hubbard absorption bands may show a strong dependence on temperature. This is not the case in LaSrFeO4, in agreement with the fact that spin-spin and orbital-orbital correlations between nearest neighbors do not vary strongly below room temperature in this compound with a high-spin 3d5 configuration and a Néel temperature of TN=366 K. [ABSTRACT FROM AUTHOR]

With established urinary markers of kidney integrity the early renal effects of lead have previously been considered to be mainly tubular or tubulointerstitial. In a cross-sectional study on 81 male lead-exposed workers and 45 age-matched controls (median blood lead concentrations 2.03 and 0.34 μmol/l respectively) not only well-established but also new urinary markers of renal integrity preferentially or exclusively located along the different nephron segments were analysed. Markers related to the glomerulus were 6-ketoprostaglandin, thromboxane B mainly produced in the glomerulus, and the extracellular matrix protein fibronectin. Markers of the proximal tubule were the brush-border antigens BBA, BB50, and HF5 and the intestinal alkaline phosphatase. Prostaglandin E and F, preferentially synthesized in the collecting duct and medullary interstitial cells, served as markers of these more distal nephron segments. In contrast to previous studies on the early phase of lead nephrotoxicity, not only tubular but also glomerular involvement could be shown in the study presented here by increases in the median values of 6-keto-prostaglandin, and decreases in fibronectin. The proximal tubular markers intestinal alkaline phosphatase and BBA confirmed that this particular segment of the nephron is affected by lead. Effects on the collecting tubule or medullary interstitial cells could also be observed. It is concluded that lead affects both the glomerulus and the tubular apparatus and that combinations of new and established markers could be valuable for a better definition and early detection of lead nephropathy. [ABSTRACT FROM PUBLISHER]