Search results for "ACETATE"
showing 10 items of 756 documents
Mathematical modeling of the biofiltration of ethyl acetate and toluene and their mixture
2009
Abstract A dynamic model for ethyl acetate and toluene removal by biofiltration is presented. Haldane-type kinetic expressions that include the oxygen limitation, the inhibition effect due to high concentration of substrate, and the cross-inhibition between substrates have been considered. A decrease in the biomass density with the bed height was proposed to represent the performance of peat biofilters over a broad range of operating conditions. Experimental yield coefficients have been derived from the experimental CO 2 production data. The unknown kinetic parameters of the model along with the coefficient for axial biomass density distribution were calibrated using experimental data from …
Evaluation of a combined activated carbon prefilter and biotrickling filter system treating variable ethanol and ethyl acetate gaseous emissions
2009
The removal of a 1:1 by weight mixture of ethanol and ethyl acetate was studied in a gas phase biotrickling filter running under conditions that simulated industrial emissions from the flexographic sector, i.e. discontinuous loading (twelve hours per day and five days per week) and oscillating concentration of the inlet stream. Three sets of experimental conditions were tested in which empty-bed residence time varied from 60 to 25s (inlet loads from 50 to 90g Cm -3 h -1 ). The biotrickling filter reached a maximum elimination capacity of 48.5g Cm -3 h -1 (removal efficiency = 68.9%) for an empty-bed residence time of 40 s. A decrease in the residence time from 40 to 25 s adversely affected …
Removal of ethyl acetate, n-hexane and toluene from waste air in a membrane bioreactor under continuous and intermittent feeding conditions
2012
BACKGROUND: European Union environmental policy has focused on abatement of volatile organic compounds (VOCs) from industrial emissions, and new European VOC emission limits have been established. This study analyzes the performance of a composite membrane bioreactor treating air stream contaminated with ethyl acetate, n-hexane and toluene under continuous and intermittent feeding conditions. RESULTS: The system was operated under continuous feeding conditions: removal efficiencies (REs) higher than 99% were obtained for inlet loads up to 200 g m−3 h−1 and empty bed residence times (EBRTs) as short as 15 s for ethyl acetate. A maximum elimination capacity of 75 g m−3 h−1 (RE ∼66%) at an EBR…
Biofiltration of ethyl acetate under continuous and intermittent loading
2007
A laboratory-scale peat biofilter was used for ethyl acetate removal from an air stream over a period lasting 1 yr. In a first stage, the biofilter was operated under continuous mode: a maximum elimination capacity of 400 g m−3 h−1 was obtained, and ethyl acetate was efficiently degraded with empty bed residence time (EBRT) as short as 22 s. The estimated yield coefficient, determined from the carbon dioxide production, resulted in 0.42 g dry biomass produced per gram of ethyl acetate consumed. The living and the dead cell concentrations were also monitored. The dead cell percentages varied between 18 and 85%, progressive increases in the dead cell percentages were achieved as EBRT decrease…
Microbial production of biopolymers from the renewable resource wheat straw.
2014
Aims Production of poly-s-hydroxybutyrate (PHB) and the chemical basic compound lactate from the agricultural crop ‘wheat straw’ as a renewable carbon resource. Methods and Results A thermal pressure hydrolysis procedure for the breakdown of wheat straw was applied. By this means, the wheat straw was converted into a partially solubilized hemicellulosic fraction, consisting of sugar monomers, and an insoluble cellulosic fraction, containing cellulose, lignin and a small portion of hemicellulose. The insoluble cellulosic fraction was further hydrolysed by commercial enzymes in monomers. The production of PHB from the sugar monomers originating from hemicellulose or cellulose was achieved by …
Influence of interactions on water and aroma permeabilities of ι-carrageenan–oleic acid–beeswax films used for flavour encapsulation
2009
The objective of this work is to investigate the water and aroma barrier properties of films obtained from ι-carrageenan containing glycerol and lipids mixtures of oleic acid (OA) and beeswax (BW) used for encapsulation of active compounds. Water vapor permeability (WVP) is greatly influenced by lipid composition, encapsulated aroma compound and also relative humidity. WVP decreases when films contain encapsulated aroma compound but increases when the moisture content in the films increases. When oleic acid was the main compound of lipid phase, the plasticizing effect of water revealed through water permeability is less marked. The results of ethyl acetate, ethyl butyrate, ethyl hexanoate, …
SAXS investigation on aggregation phenomena in supercritical CO2.
2004
Synchrotron Small-Angle X-Ray scattering (SAXS) measurements on aggregate formation of a Polyvinyl acetate- b-Perfluoro octyl acrylate (PVAc- b-PFOA) block copolymer in supercritical CO(2) are here reported. Experiments were carried out for a series of different thermodynamic conditions, changing the solvent density by profiling both the pressure at constant temperature and the temperature at constant pressure. This block copolymer and in general fluorocarbon-hydrocarbon di-blocks form aggregates depending on the value of CO(2) density. A sharp transition between monomers dissolved as random coils and micelles characterized by a solvophilic shell and a solvophobic core occurs when the CO(2)…
Glatiramer acetate during early pregnancy: A prospective cohort study
2016
Background: Only limited data are available on whether glatiramer acetate exposure during pregnancy has an effect on perinatal outcome. Objective: To determine the effect of glatiramer acetate exposure during pregnancy on pregnancy outcomes in women with multiple sclerosis. Methods: We compared the outcome of pregnancies of women with multiple sclerosis exposed to glatiramer acetate with pregnancies unexposed to disease-modifying therapies. Women were enrolled into the German Multiple Sclerosis and Pregnancy registry. A standardized questionnaire was administered during pregnancy and postpartum. Detailed information on course of multiple sclerosis and pregnancy, concomitant medications, lab…
Clusterin gene expression in apoptotic MDCK cells is dependent on the apoptosis-inducing stimulus
1995
Abstract Clusterin (Apolipoprotein J, complement lysis inhibitor) is a widely expressed multifunctional glycoprotein. The expression of clusterin mRNA has been reported to be elevated in a broad spectrum of apoptotic or degenerative tissues. More recently, it was shown that within these tissues clusterin is expressed in the surviving rather than in the dying cells, and that clusterin gene expression is actually down-regulated in the apoptotic cells. We have studied the expression of the clusterin gene in apoptotic MDCK cells. Cell death was initiated by three different stimuli: application of the steroid hormone antagonist RU 486, activation of protein kinase C by the application of the pho…
Pore-forming toxins trigger shedding of receptors for interleukin 6 and lipopolysaccharide.
1996
Cleavage of membrane-associated proteins with the release of biologically active macromolecules is an emerging theme in biology. However, little is known about the nature and regulation of the involved proteases or about the physiological inducers of the shedding process. We here report that rapid and massive shedding of the interleukin 6 receptor (IL-6R) and the lipopolysaccharide receptor (CD14) occurs from primary and transfected cells attacked by two prototypes of pore-forming bacterial toxins, streptolysin O and Escherichia coli hemolysin. Shedding is not induced by an streptolysin O toxin mutant which retains cell binding capacity but lacks pore-forming activity. The toxin-dependent c…