Search results for "DEHYDRATION"

Study of the thermal decomposition of bromazepan complexes with Co(II), Ni(II), Cu(II) and Zn(II)

1984

Abstract The thermal behaviour of complexes of bromazepan with Co(II), Ni(II), Cu(II) and Zn(II) was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The complexes decompose in two steps: dehydration and decomposition. A correlation between the dehydration temperatures of MB2Xn and the coordinating ability of X is observed.

Responses of Prunus ferganensis, Prunus persica and two interspecific hybrids to moderate drought stress

2003

Prunus ferganensis (Kost. & Riab) Kov. & Kost, a close relative of the cultivated peach (Prunus persica (L.) Batsch.), is native to arid regions of central Asia and may possess traits valuable for improving drought tolerance of commercial peach varieties. One distinguishing feature of P. ferganensis is its prominent, elongated, unbranched leaf venation pattern, which behaves as a simple recessive trait in segregating populations of P. ferganensis x P. persica hybrids. To understand whether this trait could be used as a marker in breeding for drought tolerance, we investigated the association between leaf morphological and physiological parameters related to drought response in P. ferganensi…

Anhydrobiosis in yeast: influence of calcium and magnesium ions on yeast resistance to dehydration-rehydration

2010

The influence of calcium and magnesium ions on resistance to dehydration in the yeast, Saccharomyces cerevisiae, was investigated. Magnesium ion availability directly influenced yeast cells' resistance to dehydration and, when additionally supplemented with calcium ions, this provided further significant increase of yeast resistance to dehydration. Gradual rehydration of dry yeast cells in water vapour indicated that both magnesium and calcium may be important for the stabilization of yeast cell membranes. In particular, calcium ions were shown for the first time to increase the resistance of yeast cells to dehydration in stress-sensitive cultures from exponential growth phases. It is concl…

Supported Poly(Ionic Liquid)-Heteropolyacid Based Materials for Heterogeneous Catalytic Fructose Dehydration in Aqueous Medium

2022

Two sets of four different supported catalyst materials were prepared. One set was obtained by polymerization of a bis-vinylimidazolium salt, which formed a poly(ionic liquid) coating on SiO2, TiO2, boron nitride BN, and carbon nitride C3N4. The other set was, instead, obtained by immobilizing Keggin heteropolyacid H3PW12O40 onto poly-imidazolium functionalized materials. All the catalysts, including the bare supports, were subjected to physical and chemical characterization by XRD, SEM, Specific Surface Area and pore size measurements, TGA, FTIR, and acidity-basicity measurements. The catalytic activity of the materials was tested versus the fructose dehydration in water solution at two di…

Cr(VI) sorption by intact and dehydrated Candida utilis cells: differences in mechanisms

2001

The Cr(VI) sorption kinetics by intact and dehydrated Candida utilis cells were studied. Yeast dehydration led to enhanced Cr(VI) sorption activity by cells during the first 15–20 min of rehydration. In experiments with K2Cr2O7 as a chromium source, [Cr2O7]2− was converted into [CrO4]2− during incubation with dehydrated biomass. An effect of the considerably enhanced Cr(VI) sorption activity by dehydrated cells in the buffered media at pH≈8.0 can serve as another confirmation of the different sorption mechanisms of intact and dehydrated C.utilis cells. This effect was not revealed in water solution at pH 8.0. This phenomenon will be studied in further investigations.

2018

BackgroundThe insect cuticle covers the whole body and all appendages and has bi-directionnal selective permeability: it protects against environmental stress and pathogen infection and also helps to reduce water loss. The adult cuticle is often associated with a superficial layer of fatty acid-derived molecules such as waxes and long chain hydrocarbons that prevent rapid dehydration. The waterproofing properties of cuticular hydrocarbons (CHs) depend on their chain length and desaturation number.DrosophilaCH biosynthesis involves an enzymatic pathway including several elongase and desaturase enzymes.MethodsThe link between desiccation resistance and CH profile remains unclear, so we tested…

The impact of dehydration rate on the production and cellular location of reactive oxygen species in an aquatic moss.

2012

† Background and Aims The aquatic moss Fontinalis antipyretica requires a slow rate of dehydration to survive a desiccation event. The present work examined whether differences in the dehydration rate resulted in corresponding differences in the production of reactive oxygen species (ROS) and therefore in the amount of cell damage. † Methods Intracellular ROS production by the aquatic moss was assessed with confocal laser microscopy and the ROS-specific chemical probe 2,7-dichlorodihydrofluorescein diacetate. The production of hydrogen peroxide was also quantified and its cellular location was assessed. † Key Results The rehydration of slowly dried cells was associated with lower ROS produc…

Thermal analyses of commercial magnesium stearate pseudopolymorphs

2005

Abstract Two commercial magnesium stearate powders in two well-characterised structural states are investigated using DSC and coupled TGA–DTA under dry nitrogen flow. They consist of either a mixture of crystalline hydrates or a poorly crystallised so-called anhydrate. Following the degassing of unbound water, 1 or 3 weight-loss peaks are observed below about 100 °C, each associated with one heat loss peak at the same temperature. The present results and a review of graphical data from literature show that the so-called anhydrate always contains a significant amount of water. At the beginning of the dehydration process, the heat loss is the same as the standard heat of vaporisation of water…

Immobilisation increases yeast cells' resistance to dehydration-rehydration treatment.

2014

This study was performed with the goal of revealing if the dehydration procedure used in our new immobilisation method noticeably decreases the viability of yeast cells in immobilised preparations. Various yeasts were used in this research: Saccharomyces cerevisiae cells that were rather sensitive to dehydration and had been aerobically grown in an ethanol-containing medium, a recombinant strain of S. cerevisiae grown in aerobic conditions which were completely non-resistant to dehydration and an anaerobically grown bakers' yeast strain S. cerevisiae, as well as a fairly resistant Pichia pastoris strain. Experiments performed showed that immobilisation of all these strains essentially incre…

Prediction of mass fluxes in the pervaporation process of the ethanol dehydration, based on the free volume theory

2014

Metodę obliczania współczynników dyfuzji Maxwella-Stefana opartą na współczynnikach dyfuzji własnej przewidywanych wg zależności wynikających z teorii wolnych objętości, zastosowano do obliczania strumieni masy w procesie perwaporacyjnego odwadniania etanolu na membranie z alkoholu poliwinylowego PVA. Parametry metody wolnych objętości dla badanego układu wyznaczono oraz obliczono stężenia równowagowe w PVA stosując zmodyfikowaną metodę UNIFAC-FV a następnie obliczono udziały masowe w permeacie oraz współczynniki wzbogacenia. Obliczenia przeprowadzono dla danych eksperymentalnych opublikowanych w pracy [3]. Wyniki obliczeń porównano z wynikami uzyskanymi na instalacji doświadczalnej.