Search results for "DEHYDRATION"

Harmonic behavior of trehalose-coated carbon-monoxy-myoglobin at high temperature.

1999

Abstract Embedding biostructures in saccharide glasses protects them against extreme dehydration and/or exposure to very high temperature. Among the saccharides, trehalose appears to be the most effective bioprotectant. In this paper we report on the low-frequency dynamics of carbon monoxy myoglobin in an extremely dry trehalose glass measured by neutron spectroscopy. Under these conditions, the mean square displacements and the density of state function are those of a harmonic solid, up to room temperature, in contrast to D 2 O-hydrated myoglobin, in which a dynamical transition to a nonharmonic regime has been observed at ∼180K (Doster et al., 1989. Nature. 337:754–756). The protective ef…

Sensitivity analysis and process optimization of a natural gas dehydration unit using triethylene glycol

2019

Abstract Dehydration of natural gas by absorption using triethylene glycol (TEG) is a common industrial offshore procedure to ensure the compliance with the required water dew point specifications for midstream transportation. Two thermodynamic models, the UMR-PRU and the TST/NRTL, are applied for the process simulation while a preliminary economic evaluation has been conducted revealing that both yield overall similar results as for the fixed capital cost which is found to be in good agreement with reported literature values. Moreover, sensitivity analysis of several operational parameters of the process has been performed and optimized values are suggested aiming to reduce its energy requ…

Proposal of Isobutyl Alcohol as Entrainer To Separate Mixtures Formed by Ethanol and Water and 1-Propanol and Water

2017

Isobutyl alcohol (IBA) has been proposed as a solvent to carry out the dehydration of ethanol and 1-propanol by means of a nonconventional distillation process. In this way, isobaric vapor–liquid equilibrium (VLE) and vapor–liquid–liquid equilibrium (VLLE) data at atmospheric pressure have been obtained for the ternary systems ethanol (1a) + water (2) + IBA (3) and 1-propanol (1b) + water (2) + IBA (3). Then, these data have been correlated to obtain a set of parameters capable of estimating VLE and VLLE. According to the results achieved, distillation sequences to separate water and ethanol or 1-propanol have been proposed. Finally, a study about the minimum amount of entrainer required to…

Flame-burned stainless steel wire spheres as carriers ofZymomonas mobilis cells and extracellular levansucrase

1999

In the present work, the use of flame-burned WS as carriers of Z. mobilis and extracellular levansucrase and the effect of the cell fixation method by dehydration on system productivity were investigated. Lyophilization and convective drying of Z. mobilis biomass at 30°C to a moisture content of 10–14% gave the best results for the repeated batch fermentations of a sucrose medium to obtain levan and ethanol. Significant correlation between the product formation and the concentration of free cells in the fermentation medium was established. Clearly, the cells were weakly bound to the newly generated WS and were washed out into the medium during fermentation. Here the hypothesis is presented …

Thermodynamic Analysis and Process Simulation of Ethanol Dehydration via Heterogeneous Azeotropic Distillation

2014

The heterogeneous azeotropic distillation process is widely used to separate nonideal binary mixtures into their constituent pure components. This method uses the addition of a third component, called an entrainer, to cause liquid–liquid phase separation over a broad range of compositions in the ternary phase diagram. Ethanol dehydration was used as a case study and diisopropyl ether and isobutyl alcohol were analyzed as possible entrainers in a heterogeneous azeotropic distillation. In this way, isobaric vapor–liquid–liquid equilibrium was measured for the ethanol + water + diisopropyl ether or + isobutyl alcohol ternary mixtures at 101.3 kPa. The data were correlated by the NRTL and UNIQU…

Attachment of yeast to modified stainless steel wire spheres, growth of cells and ethanol production

1999

Abstract The immobilization of yeast Saccharomyces cerevisiae, their growth and ethanol production were investigated using untreated and modified stainless steel wire spheres (WS) as carriers. The carrier surface was modified by oxidation, by treatment with titanium (IV) chloride (TiCl4) or by γ-aminopropyltrietoxysilane (AS) in an attempt to raise the efficiency of the immobilization of the yeast cells. The influence of the cell fixation method on culture growth and ethanol synthesis was investigated. The immobilization of cells to carrier surface was checked by scanning electron microscopy (SEM). More closely attachment of yeast cells was seen on the aminated wire surface. It was establis…

Anhydrobiosis in Non-conventional Yeasts

2019

Anhydrobiosis is a unique state of living organisms that provides the possibility of surviving conditions of extreme heat and drought with temporary and reversible suspended processes of metabolism. Beyond its ecological importance in nature, it is used for the production of viable dry microbial preparations, including active dry yeast. During the last decade, this state has also been studied in non-conventional yeasts (NCY), mainly because of the necessity of active dry wine yeasts. At the same time, many other modern biotechnological processes are also linked to the use of NCY. Correspondingly, this implies an interest in the long-term maintenance of various species of NCY in a viable dry…

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…

The impact of pulsed electric fields on quality parameters of freeze‐dried red beets and pineapples

2020

DEEP EUTECTIC SOLVENTS E LIQUIDI IONICI: SOLVENTI PER LO SVILUPPO DI PROCESSI ECO-COMPATIBILI

2020

L’obiettivo di questi tre anni di Dottorato è stato lo studio e l’utilizzo nuovi solventi di reazione in grado di sostituire i solventi organici classici. In particolare sono stati studiati i Deep Eutectic Solvent (DES) e le miscele di Liquidi Ionici (IL). I DES sono stati utilizzati come solventi per lo studio di reazioni organiche, usate per la formazione di nuovi legami C-C. Nello specifico sono state studiate la reazione di Diels-Alder, e diverse reazioni di coupling C-C catalizzate da Pd. In seguito, i DES sono stati utilizzati per la formazione di nuovi gel supramolecolari, chiamati eutectogel. Questi gel sono stati formati usando come gelator amminoacidi naturali, consentendo quindi …