Search results for "spray"
showing 10 items of 503 documents
Derivation of Models for Thin Sprays from a Multiphase Boltzmann Model
2017
We shall review the validation of a class of models for thin sprays where a Vlasov type equation is coupled to an hydrodynamic equation of Navier–Stokes or Stokes type. We present a formal derivation of these models from a multiphase Boltzmann system for a binary mixture: under suitable assumptions on the collision kernels and in appropriate asymptotics (resp. for the two different limit models), we prove the convergence of solutions to the multiphase Boltzmann model to distributional solutions to the Vlasov–Navier–Stokes or Vlasov–Stokes system. The proofs are based on the procedure followed in Bardos et al. (J Stat Phys 63:323–344 (1991), [2]) and explicit evaluations of the coupling term…
1 H,13 C, 19 F NMR, and ESI mass spectral characterization of two geminal difluorosteroids
2008
Two geminal difluorosteroids, 3,3-difluoro-5β-cholan-24-oic acid (1) and 3,3-difluoro-5α-androstan-17-one (2), have been prepared from corresponding ketosteroids with diethylaminosulphurtrifluoride (DAST) treatment in moderate yields. The structures of 1 and 2 have been characterized by 1H, 13C, 19F NMR, and ESI mass spectral techniques. Copyright © 2008 John Wiley & Sons, Ltd.
Identification and cloning of odorant binding proteins from the scarab beetle Phyllopertha diversa.
1999
Abstract Wehave identified, cloned, and characterized two odorant binding proteins from the pale brown chafer, Phyllopertha diversa. One of the proteins (OBP1, 116 amino acids long) showed high amino acid identity (>90%) to two previously identified PBPs from scarab beetles. The second protein (OBP2) showed limited sequence similarity to lepidopteran and dipteran OBPs, but contained only 133 amino acids. Both proteins showed the occurrence of six highly conserved cysteines; electrospray mass spectral data suggested they are all bound in three disulfide bonds. During purification, OBP2 separated into several isoforms; N-terminal amino acid sequencing and electrospray ionization mass spectrom…
The metal binding abilities of Megathura crenulata metallothionein (McMT) in the frame of gastropoda MTs.
2011
Metallothioneins (MTs) are proteins that play a major role in metal homeostasis and/or detoxification in all kind of organisms. The MT gene/protein system of gastropod molluscs provides an invaluable model to study the diversification mechanisms that have enabled MTs to achieve metal-binding specificity through evolution. Most pulmonate gastropods, particularly terrestrial snails, harbor three paralogous isogenes encoding three MT isoforms with different metal binding preferences: the highly specific CdMT and CuMT isoforms, for cadmium and copper respectively, and the unspecific Cd/CuMT isoform. Megathura crenulata is a non-pulmonate gastropod in which only one MT isogene has so far been re…
Determination of pharmaceuticals in soils and sediments by pressurized liquid extraction and liquid chromatography tandem mass spectrometry
2010
13 páginas, 4 figuras, 6 tablas.
Two new triterpenoid saponins fromPittosporum senaciaPutterlick (Pittosporaceae)
2012
From the branches of Pittosporum senacia Putterlick (Pittosporaceae), two new triterpenoid saponins, senaciapittosides A and B (1, 2), were isolated. Their structures were elucidated by extensive analysis of one- and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution electrospray ionization mass spectrometry (HR-ESIMS) and chemical evidence as 3-O-[β-d-glucopyranosyl-(1 2)]-[α-l-arabinopyranosyl-(1 3)]-[α-l-arabinofuranosyl-(1 4)]-β-d-glucuronopyranosyl oleanolic acid 28-O-β-d-glucopyranosyl ester (1) and 3-O-[β-d-glucopyranosyl-(1 2)]-[α-l-arabinopyranosyl-(1 3)]-[α-l-arabinofuranosyl-(1 4)]-β-d-glucuronopyranosyl-22-O-α-l-arabinopyranosyl-21-acetoxy R1-barrigen…
Etude et modélisation du comportement des gouttelettes de produits phytosanitaires sur les feuilles de vignes par imagerie ultra-rapide et analyse de…
2013
In the domain of vineyard precision spraying research, one of the most importantobjectives is to minimize the volume of phytosanitary products ejected bya sprayer in order to be more environmentally respectful with more effectivevine leaf treatments. Unfortunaltely, even if lot of works have been carriedout at a parcel scale, mainly on losses caused by drift, less works have beencarried out at the leaf scale in order to understand which parameters influencethe spray quality. Since few years, recent improvements in image processing,sensitivity of imaging systems and cost reduction have increased the interestof high-speed imaging techniques. Analyzing the behavior of droplets afterimpact with…
Modélisation d'images agronomiques - application a la reconnaissance d'adventices par imagerie pour une pulvérisation localisée
2009
Plant (crop and weed) identification is a very active field of research in agriculture since the reinforcement of European laws about pesticide applications for a site-specific management of spraying practices. A new crop/weed simulation model was developed to allow the evaluation of crop/weed spatial identification methods from imaging. Considering multiples agronomic parameters – crop location, weed infestation rate, weed spatial distribution – the first step of this model allows the simulation of an infested crop field. Then, in a second step, a world to camera transformation is applied to allow every kind of picture (with or without perspective effect). The validation of this model was …
Capillary zone electrophoresis of alkaloids
1998
Abstract A comprehensive discussion of important aspects for the analysis of alkaloids by capillary zone electrophoresis (CZE) is given. The influence of structure on the electrophoretic mobility (EM) of indole alkaloids was investigated using a running buffer which is generally applicable to the CZE analysis of alkaloids. The EM, which at the applied conditions was mostly dependent on the size and shape of the solvated analyte ions, was additionally affected by the presence of hydrogen bonds or ion–dipole interactions between protonated and unprotonated alkaloids of the same species. This could be derived from the existence of alkaloidal dimer cluster ions [2M+H]+ when mass spectrometry wa…
General approach for the analysis of various alkaloid classes using capillary electrophoresis and capillary electrophoresis-mass spectrometry
1997
Abstract The analysis of various alkaloid classes employing capillary electrophoresis (CE) and on-line combined CE-mass spectrometry (CE-MS) is described. A CE method is presented for the analysis of alkaloids without derivatisation or purification. The separation of four different groups of alkaloids consisting of monoterpenoid indole alkaloids, protoberberines/benzophenanthridines, β-carboline alkaloids, and isoquinolines from poppy by free zone capillary electrophoresis has been obtained using a 1:1 mixture of 100 mmol 1 −1 ammonium acetate (pH 3.1) and acetonitrile. The influence of alkaloid structure on the electrophoretic mobility is discussed. The CE-MS reconstructed total ion curren…