Do changes of pen and penmate affect the behaviour of heifers?

We wanted to investigate if relocation affects behaviour of dairy heifers. In the study 32 Holstein heifers were housed in pairs until they were 13 months old. 16 heifers stayed in the same pen with the same penmate (control). The pen and penmates of 16 heifers were changed 16 times between 11 and 13 months of age

Etude de la liaison hydrogène par spectroscopie vibrationnelle et simulation dynamique moléculaire d'alcools en condition supercritique

Le travail présenté dans cette thèse a pour objet l'étude de la liaison hydrogène dans les alcools en conditions supercritiques. Des expériences de spectroscopies infrarouge et Raman ont été réalisées sur trois alcools (méthanol, éthanol et tert-butanol) dans une large gamme de pressions (de 0,1 à 25 Mpa), le long de l'isotherme 523 K, permettant d'explorer un domaine de densités réduites compris entre 0,1 et 2. Le domaine spectral associé à la vibration d'élongation O-H de ces alcools a été analysé à l'aide d'un modèle original d'agrégats, conduisant à une information quantitative de l'état d'agrégation dans ces systèmes. Parallèlement aux expériences, des simulations de dynamique moléculaire ont apporté de nombreuses informations au niveau microscopique et ont démontré, notamment, la pertinence du modèle d'agrégats proposé.This work deals with the study of hydrogen bonding in supercritical alcohols. Three alcohols (namely methanol, ethanol and tert-butanol) were studied by infrared and Raman spectroscopy (0.1-25 MPa pressure range) along the isotherm 523K allowing us to investigate reduced density ranging between 0.1 and 2. The spectral domain associated with the OH stretching mode was analysed with an original cluster model leading to quantitative information on the aggregation state in these systems. Concurrently with experiments, molecular dynamic simulations have provided further information at the microscopic level validating in particular the cluster model used in the spectroscopic investigation

Mesure de la vitesse de déplacement d'un arc de coupure sur une electrode plane

Dans cet article les auteurs montrent comment ils ont mesuré la vitesse de déplacement sur une surface plane métallique, d'un pied d'arc électrique parcouru par un courant compris entre 500 et 3 000 A. Le dispositif expérimental réalisé permet d'effectuer les mesures nécessaires en temps réel sans perturber le phénomène. Les résultats illustrent le caractère instable du plasma et montrent que le déplacement s'effectue de manière aléatoire

Natural deep eutectic solvents as thermostabilizer for Humicola insolens cutinase

As a new generation of green solvents, deep eutectic solvents (DESs) are considered a promising alternative to current harsh organic solvents and find application in many chemical processing methods such as extraction and synthesis. DESs, normally formed by two or more components via various hydrogen bond interactions, offer high potential as medium for biocatalysis reactions where they can improve efficiency by enhancing substrate solubility and the activity and stability of the enzymes. In the current study, the stabilization of Humicola insolens cutinase (HiC) in natural deep eutectic solvents (NADESs) was assessed. The best hydrogen bond donor among sorbitol, xylitol, erythritol, glycerol and ethylene glycol, and the best acceptor among betaine, choline chloride, choline acetate, choline dihydrogen citrate and tetramethylammonium chloride, were selected, evaluating binding energies and molecular orientations through molecular docking simulations, and finally used to prepare NADES aqueous solutions. The effects of component ratio and NADES concentration on HiC thermostability at 90 degrees C were also investigated. The choline dihydrogen citrate:xylitol, in a 1:1 ratio with a 20 wt% concentration, was selected as the best combination in stabilizing HiC, increasing its half-life three-fold

Étude des grandeurs caractéristiques de la tache cathodique d'un arc électrique

The cathode of an electric arc burning freely in air was studied during a half-wave of a sinusoidal, 50 Hz current. For mean intensities ranging from 500 to 2 000 A, five characteristic parameters for the cathode spot were determined : the mean radius a, the temperature T, the electric field E, the total current density J, and the fraction s of the current density due to electrons. The experimental measurement of the erosion of the cathode together with five simultaneous equations enabled the parameters above to be obtained for copper and silver electrodes. The first part of the results gives mean values. The second part shows the changes occuring in the cathode spot as a function of time for the half-wave of the current.On étudie la cathode d'un arc électrique brulant librement dans l'air pendant une demi-alternance d'un courant sinusoïdal de fréquence 50 Hz. Nous avons déterminé pour des intensités moyennes variant entre 500 et 2 000 A cinq grandeurs physiques caractéristiques de la tache cathodique : le rayon moyen a, la température T, le champ électrique E, la densité totale de courant J et la fonction s de la densité de courant due aux électrons. La mesure expérimentale de l'érosion de la cathode associée à un système de cinq équations a permis d'obtenir ces grandeurs pour des électrodes en cuivre et en argent. La première partie des résultats donne des valeurs moyennes, tandis que la deuxième partie montre l'évolution de la tache cathodique en fonction du temps pour la demi-alternance de courant

1D and 2D NMR Spectroscopy of Bonding Interactions within Stable and Phase-Separating Organic Electrolyte-Cellulose Solutions

Organic electrolyte solutions (i.e. mixtures containing an ionic liquid and a polar, molecular co-solvent) are highly versatile solvents for cellulose. However, the underlying solvent–solvent and solvent–solute interactions are not yet fully understood. Herein, mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate, the co-solvent 1,3-dimethyl-2-imidazolidinone, and cellulose are investigated using 1D and 2D NMR spectroscopy. The use of a triply-13C-labelled ionic liquid enhances the signal-to-noise ratio for 13C NMR spectroscopy, enabling changes in bonding interactions to be accurately pinpointed. Current observations reveal an additional degree of complexity regarding the distinct roles of cation, anion, and co-solvent toward maintaining cellulose solubility and phase stability. Unexpectedly, the interactions between the dialkylimidazolium ring C2−H substituent and cellulose become more pronounced at high temperatures, counteracted by a net weakening of acetate–cellulose interactions. Moreover, for mixtures that exhibit critical solution behavior, phase separation is accompanied by the apparent recombination of cation–anion pairs

Polyaniline coated conducting fabrics : chemical and electrochemical characterization

Polyaniline coated conducting fabrics have been obtained by chemical oxidation of aniline by potassium peroxydisulfate on polyester fabrics. Two different acids have been employed to carry out the synthesis (HCl and H2SO4), obtaining the best results of conductivity with the latter one. The conducting fabrics have been characterized chemically by means of Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), energy dispersive X-Ray (EDX) and X-ray photoelectron spectroscopy (XPS). The morphology of the coatings has been observed by means of scanning electron microscopy (SEM). The conducting properties of the fabrics have been measured by means of electrochemical impedance spectroscopy (EIS). The electrochemical characterization has been carried out by means of cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). The conducting fabrics have also shown electrochromic properties, changing its color from green yellowish at −1 V to dark green at +2 V. The durability of the coating has been evaluated by means of washing and rubbing fastness tests.Authors thank to the Spanish Ministerio de Ciencia e Innovacion and European Union Funds (FEDER) (contract CTM2010-18842-C02-02) and Universitat Politecnica de Valencia (Primeros Proyectos de Investigacion (PAID-06-10)) for the financial support. J. Molina is grateful to the Conselleria d'Educacio (Generalitat Valenciana) for the FPI fellowship