Search results for "Hydration"
showing 10 items of 217 documents
Supported H3PW12O40 for 2-propanol (photo-assisted) catalytic dehydration in gas-solid regime: The role of the support and of the pseudo-liquid phase…
2016
Abstract Catalytic and photocatalytic 2-propanol dehydration was carried out by using a supported Keggin heteropolyacid H3PW12O40 (PW12). Binary materials were prepared by impregnation and/or solvothermal treatment by using commercial supports: SiO2 (Mallinckrodt), TiO2 (Evonik P25) and multiwall carbon nanotubes (Sunnano) or home solvothermically prepared SiO2 and TiO2. All the materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM) coupled with EDX microanalysis, specific surface area measurements, diffuse reflectance spectroscopy (DRS), FTIR and Raman spectroscopy. (Photo)catalytic 2-propanol dehydration was studied in gas-solid regim…
Can pressure-induced cell inactivation be related to cell volume compression? A case study for Saccharomyces cerevisiae
2013
In this paper, emphasis has been put on the relationship between volume compression and cell inactivation for the Saccharomyces cerevisiae strain CBS 1171 submitted to high hydrostatic pressure treatments. The influence of cell dehydration on pressure inactivation was first investigated. Inactivation was found to be strongly limited, or even completely prevented for cells with a water content of 60% w/w or below. Moreover, the volume compression undergone by a single yeast cell was assessed as a function of pressure and hydration conditions using a high-pressure setup for pressure-volume-temperature measurements. Direct measurements of volume compression were performed on cell pellets after…
CRYOPRESERVATION OF PEACH SHOOT TIPS BY ENCAPSULATION DEHYDRATION
2011
Cryopreservation of Italian cultivars of hazelnut
2021
The present study was performed to optimise the cryopreservation protocol in Italian cultivars of Corylus avellana L. Lateral buds excised from in vitro grown plantlets of ‘Tonda Gentile Romana’ (TGR) and ‘Montebello’ (MB) were cryopreserved by the encapsulation-dehydration technique. The effect of dehydration of beads with sucrose (0.5, 0.75 or 1 M) for 1 or 3 days, of desiccation with silica gel for 6 or 8 h and of application of two cytokinins (N6-benzyladenine or meta-Topolin) in the regrowth phase was evaluated. The highest regrowth was obtained dehydrating alginate beads with 0.75 M sucrose applied for 1 day and with desiccation for 8 h with silica gel in both cultivars. On the other …
Interactions ciment-organofunctional silanes : implications on hydration and on mechanical properties of the modified systems
2010
Nowadays concrete is the most attractive option for the construction sector. This is because concrete itself is a low cost, low energy and low environmental impact material. Moreover, concrete structures are very durable and high load bearing. This is achieved by incorporating steel, because concrete itself is a very low tensile strength material. Chemically, the weakness originates in the cohesive nature of cement used for concrete making. Nanoscale experimental investigations and numerical simulations showed that cohesion of cement paste is caused by short range surface forces acting between calcium silicate hydrates (C-S-H) in the interstitial solution. This thesis addresses the possibil…
Hydration dependent dynamics in sol-gel encapsulated myoglobin.
2008
In this work we study the effect of hydration on the dynamics of a protein in confined geometry, i.e. encapsulated in a porous silica matrix. Using elastic neutron scattering we investigate the temperature dependence of the mean square displacements of non-exchangeable hydrogen atoms of sol-gel encapsulated met-myoglobin. The study is extended to samples at 0.2, 0.3 and 0.5 g water/g protein fractions and comparison is made with met-myoglobin powders at the same average hydration and with a dry powder sample. Elastic data are analysed using a model of dynamical heterogeneity to take into account deviations of elastic intensity from gaussian behaviour in a large momentum transfer range and r…
Immobilisation of yeast cells on the surface of hydroxyapatite ceramics
2011
Hydroxyapatite (HAP) ceramics was tested for the first time for the possibility of being used as a new carrier for the immobilisation of yeast cells that are both model organisms for eukaryotic cell investigations and producers, which is important in classical and modern biotechnological processes. It was shown that under typical immobilisation conditions yeast (Saccharomyces cerevisiae) has no affinity to HAP ceramics. A novel method for yeast immobilisation was developed. This new method includes the joint incubation of a carrier with the cells, the sedimentation and adhesion of cells on the carrier and the dehydration of obtained preparations. It was shown that the sedimentation and adhe…
Dehydration potential of ultrathin clouds at the tropical tropopause
2003
[1] We report on the first simultaneous in situ and remote measurements of subvisible cirrus in the uppermost tropical troposphere. The observed cirrus, called UTTCs ( ultrathin tropical tropopause clouds), are the geometrically (200-300 m) and optically (t approximate to 10(-4)) thinnest large-scale clouds ever sampled (approximate to10(5) km(2)). UTTCs consist of only a few ice particles per liter with mean radius approximate to5 mum, containing only 1-5 % of the total water. Yet, brief adiabatic cooling events only 1-2 K below mean ambient temperature destabilize UTTCs, leading to large sedimenting particles (r approximate to 25 mm). Due to their extreme altitude above 17 km and low part…
Physical pre-treatment of plums (Prunus domestica). Part 1. Modelling the kinetics of drying
2002
An alternative physical method for enhancing the drying rate of plums is proposed. It consists of the superficial abrasion of the plums' peel using an inert abrasive material to remove the cuticular waxy layer, the limiting factor for moisture loss. The physical pre-treatment was compared with a chemical treatment in which the plums were dipped into a solution of ethyl oleate. The drying kinetics of the above samples, including the untreated one, were reconstructed by using a mathematical model. The drying process, carried out at 60 C to reduce the prunes' quality loss, showed the great capability of both pre-treatments to enhance water diffusivity in the plum peel with respect to the untre…