Smectite clay adsorbents of aflatoxin B1 to amend animal feed

Smectite clay has been shown in studies over the past 20 years to sorb aflatoxin B1 (AfB1) in animal feed and thereby reduce its toxic influence on animals. In this study, 20 smectite samples were selected from industrial products or reference minerals. In the initial steps, it was shown that AfB1 entered the interlayer galleries of smectites and a 10-fold range in sorption ability was observed in a set of 20 smectite samples. Yet, it was not clear which clay properties (CEC, pH, base saturation) influenced this variation. In an effort to further explore properties that might influence the sorption of AfB1, three good sorbent samples were chosen from our set of 20 samples along with one sample of low sorption capacity. Those samples were fractionated into sand, silt, coarse clay (CC), and fine clay (FC) fractions. From all sample fractions, sorption isotherms and X-ray diffraction patterns were obtained. Additionally, a vermiculite and a palygorskite were examined with regard to sorption capacity. Concentration of smectite and their adsorption test suggest that differences in smectite composition are responsible for difference in sorption, not so much their relative abundance or other mineral phases. Initial infrared analysis indicates that weathered aluminous smectites, which have no octahedral iron or magnesium, belong to the poor AfB1 sorbents. Palygorskite and vermiculite are not effective sorbents. Based on the findings in this study, tentative quality criteria of sorbent selection for their use in animal feed were established. These criteria are: pH between 6.5 and 8.5, CEC > 75cmolc/kg, organic carbon < 2.5 g/kg, expression of XRD smectite peak and AlFeOHbending in FTIR and Langmuir adsorption capacity for AfB1 > 0.40 mol/kg

Installations sportives: Economie d’entreprise

Panorama des questions que posent, sur le plan de l’économie d’entreprise, la planification, la construction et l’exploitation des installations sportives

Kinetics of heterogeneous bubble nucleation in rhyolitic melts: implications for the number density of bubbles in volcanic conduits and for pumice textures

International audienceWe performed decompression experiments to simulate the ascent of a phenocryst-bearing rhyolitic magma in a volcanic conduit. The starting materials were bubble-free rhyolites water-saturated at 200 MPa–800°C under oxidizing conditions: they contained 6.0 wt% dissolved H2O and a dense population of hematite crystals (8.7 ± 2 9 105 mm-3). Pressure was decreased from the saturation value to a final value ranging from 99 to 20 MPa, at constant temperature (800C); the rate of decompression was either 1,000 or 27.8 kPa/s. In all experiments, we observed a single event of heterogeneous bubble nucleation beginning at a pressure PN equal to 63 ± 3 MPa in the 1,000 kPa/s series, and to 69 ± 1 MPa in the 27.8 kPa/s series. Below PN, the degree of water supersaturation in the liquid rapidly decreased to a few 0.1 wt%, the nucleation rate dropped, and the bubble number density (BND) stabilized to a value strongly sensitive to decompression rate: 80 mm-3 at 27.8 kPa/s vs. 5,900 mm-3 at 1,000 kPa/s. This behaviour is like the behavior formerly described in the case of homogeneous bubble nucleation in the rhyolite-H2O system and in numerical simulations of vesiculation in ascending magmas. Similar degrees of water supersaturation were measured at 27.8 and 1,000 kPa/s, implying that a faster decompression rate does not result in a larger departure from equilibrium. Our experimental results imply that BNDs in acid to intermediate magmas ascending in volcanic conduits will depend on both the decompression rate jdP=dtj and the number density of phenocrysts, especially the number density of magnetite microphenocrysts (1–100 mm-3), which is the only mineral species able to reduce significantly the degree of water supersaturation required for bubble nucleation. Very low BNDs (&1 mm-3) are predicted in the case of effusive eruptions (jdP=dtj & 0.1 kPa/s). High BNDs (up to 107 mm-3) and bimodal bubble size distributions are expected in the case of explosive eruptions: (1) a relatively small number density of bubbles (1–100 mm-3) will first nucleate in the lower part of the conduit (jdP=dtj & 10 kPa/s), either at high pressure on magnetite or at lower pressure on quartz and feldspar (or by homogeneous nucleation in the liquid) and (2) then, extreme decompression rates near the fragmentation level (jdP=dtj & 103 kPa/s) will trigger a major nucleation event leading to the multitude of small bubbles, typically a few micrometers to a few tens of micrometers in diameter, which characterizes most silicic pumices

Sportanlagen: Betriebswirtschaftliche Aspekte

Behandlung betriebswirtschaftlicher Themen bei Planung, Bau und Betrieb von Sportanlagen

Bäder: Grundlagen für Planung, Bau und Betrieb

Umfassende Planungsgrundlagen für die fachgerechte Objektplanung. Hinweise zu Bedarfswerten, Abmessungen, Organisation, Technik und Energietechnik. Vorgehen bei Neubau, Umbau und Sanierung

Piscines: Principes de planification

Bases détaillées de planification; besoins; dimensionnement, l’organisation, technique et technique énergétique. Procédure de construction, de rénovation, d’assainissement