Cent Of Residues Research Articles

Method Validation, Dissipation and Decontamination of Flubendiamide Residues in Lettuce using LC/MS/MS

A method for determining flubendiamide residues in lettuce using LCMS/MS with negative electron spray ionization was developed and used for its residue analysis. Samples were extracted in acetonitrile and cleaned up by dispersive solid phase extraction with recovery of 70 to 120 per cent at RSD < 20 per cent. The residues dissipated on 25 and 30 d of application of flubendiamide at 24 and 48 g a.i. ha−1 respectively on lettuce. Tamarind water washing was found very effective for decontamination of flubendiamide residues from iceberg lettuce. It removed 91.62 and 82.11 per cent of residues at the recommended and double the recommended doses.

Experimental review of oxygen content at mixing layer in cone calorimeter

This work aims to elucidate whether the hypothesis of zero oxygen at the mixture layer when flame takes place is assumable for every kind of material. For that purpose, we investigated the oxygen concentration there by cone calorimeter tests. A modified holder was developed in order to collect oxygen in this mixture layer. In addition, thermogravimetric tests were carried out so as to relate the possible effects of the presence of oxygen in the atmosphere where the pyrolysis process takes place, since the cone calorimeter does not allow to control the oxygen level of the atmosphere during the experiment. The reaction rates and per cent of residue in the cone calorimetric tests were measured and compared with the results from thermogravimetric tests. Six products were analysed which can be classified in three main groups: lignocellulosic, thermoplastic polymers and thermoset polymers. Cone calorimetric results showed that for some of the materials analysed (PET, Nylon and PUR foam) the oxygen level at mixture layer decreased until values close to zero. The comparison of reaction rates between cone calorimetric and thermogravimetric tests revealed the char layer created in cone calorimetric tests over the exposed face for brushed fir, Nylon and PET established an important heat barrier that modifies the thermal behaviour of these materials.

Microbial grazer populations in a 15N labelled organic residue and the uptake of residue N by wheat

The aim of this study was to determine the extent and timing of mineral N release from a localized source of decomposing residue (hotspot) and its subsequent uptake by a growing plant, in relation to changes in the populations of microbial-feeding nematodes and protozoa. Dried and ground ryegrass labelled with 15N was used to create a hotspot at a depth of 30 cm in a column of clay-loam soil. Wheat plants grown in the columns were harvested after 10, 16, 22, 28 and 34 days and analyzed for total N and 15N content, along with simultaneous measurements of soil mineral N and microfauna. There was a rapid increase in microfauna and mineral N, indicating rapid mineralization activity. A total of 25 per cent of the N initially in the residue was present in the wheat plants after 34 days. The pattern of residue N uptake was sigmoidal, with 62 per cent of residue N uptake occurring between days 16-22. The importance of synchronization between mineralization and plant N uptake is discussed.

Two-dimensional 1H, 15N NMR investigation of uniformly 15N-labeled lac repressor headpiece.

15N uniformly labeled lac repressor and lac repressor headpiece were prepared. 15N NMR spectra of lac repressor were shown resolution inadequate for detailed study while the data showed that the 15N labeled N-terminal part of the protein is quite suitable for this type of study allowing future investigation of the specific interaction of the lac repressor headpiece with the lac operator. We report here the total assignment of proton 1H and nitrogen 15NH backbone resonances of this headpiece in the free state. Assignments of the 15N resonances of the protein were obtained in a sequential manner using heteronuclear multiple quantum coherence (HMQC), relayed HMQC nuclear Overhauser and relayed HMQC-HOHAHA spectroscopy. More than 80 per cent of residues were assigned by their 15NH(i)-N1H(i + 1) and 15NH(i)-N1H(i - 1) connectivities. Values of the 3JNH alpha splitting for 39 of the 51 residues of the headpiece were extracted from HMQC and HMQC-J. The observed 15NH(i)-C beta H cross peaks and the 3JNH alpha coupling constants values are in agreement with the three alpha-helices previously described [Zuiderweg, E.R.P., Scheek, R.M., Boelens, R., van Gunsteren, W.F. and Kaptein, R., Biochimie 67, 707 (1985)]. The 3JNH alpha coupling constants can be now used for a more confident determination of the lac repressor headpiece. From these values it is shown that the geometry of the ends of the second and third alpha-helices exhibit deviation from the canonical alpha-helix structure. On the basis of NOEs and 3JNH alpha values, the geometry of the turn of the helix-turn-helix motif is discussed.

Composition of Gum Tumentines of Pines. XIII. A Report on Pinus albicauclis

The oleoresin of P. albicaulis contains 31 per cent volatile oil and 69 per cent rosin. By fractional distillation, the gum turpentine was found to contain approximately 32 per cent Δ3-carene, 3 per cent a-terpinyl acetate, 10 per cent cadinene, 42 per cent albicaulene, 0.2 per cent albicaulol, 2.5 per cent cembrene, and about 4 per cent of residue and resinous fractions. In this unusual turpentine three compounds not previously reported as constituents of essential oils were found. Albicaulene is a monocyclic sesuiterne and is related to the monocyclic tertiary sesquiterpene alcohol, albicaulol. The diterpene, cembrene, is a monocyclic diterpene.