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Chemical Pretreatment (chemical + pretreatment)

Distribution by Scientific Domains

Life Sciences	40%

Selected Abstracts

Design of dual-purpose membrane desalination systems

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2010
Rajindar Singh
Abstract Reverse osmosis (RO) and nanofiltration (NF) membrane plants are used extensively for brackish water desalination and industrial water purification. The operating range of RO plants is 60,80% product water recovery depending on the quality of raw water and feed water pretreatment. Typically, these plants operate at 75% recovery. The disposal of RO reject streams (20,40% of plant feed water) containing high concentration of salts is becoming an environmental problem. To reduce brine disposal costs and to increase product water recovery, several high-recovery energy-efficient membrane processes were analyzed. Generally speaking, a balance is required between brine volume reduction, capital and operating costs, energy consumption, and process simplicity. The analyses showed that up to 90% product water recovery can be achieved for low to medium brackish feed waters using RO/NF membrane systems with minimal feed water chemical pretreatment. The benefits of hybrid membrane systems integrated with fuel cell alternate energy systems are discussed. © 2009 American Institute of Chemical Engineers Environ Prog, 2010 [source]

Bioconversions of maize residues to value-added coproducts using yeast-like fungi,

FEMS YEAST RESEARCH, Issue 2 2003
Timothy D Leathers
Abstract Agricultural residues are abundant potential feedstocks for bioconversions to industrial fuels and chemicals. Every bushel of maize (approximately 25 kg) processed for sweeteners, oil, or ethanol generates nearly 7 kg of protein- and fiber-rich residues. Currently these materials are sold for very low returns as animal feed ingredients. Yeast-like fungi are promising biocatalysts for conversions of agricultural residues. Although corn fiber (pericarp) arabinoxylan is resistant to digestion by commercially available enzymes, a crude mixture of enzymes from the yeast-like fungus Aureobasidium partially saccharifies corn fiber without chemical pretreatment. Sugars derived from corn fiber can be converted to ethanol or other valuable products using a variety of naturally occurring or recombinant yeasts. Examples are presented of Pichia guilliermondii strains for the conversion of corn fiber hydrolysates to the alternative sweetener xylitol. Corn-based fuel ethanol production also generates enormous volumes of low-value stillage residues. These nutritionally rich materials are prospective substrates for numerous yeast fermentations. Strains of Aureobasidium and the red yeast Phaffia rhodozyma utilize stillage residues for production of the polysaccharide pullulan and the carotenoid astaxanthin, respectively. [source]

Direct exposure electron ionization mass spectrometry and gas chromatography/mass spectrometry techniques to study organic coatings on archaeological amphorae

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2005
Maria Perla Colombini
Abstract Two different analytical approaches, direct exposure electron ionization mass spectrometry (DE-MS) and gas chromatography/mass spectrometry (GC/MS), were compared in a study of archaeological resinous materials. DE-MS was found to be an efficient fingerprinting tool for the fast screening of organic archaeological samples and for providing information on the major components. GC/MS appeared to be more efficient in unravelling the sample composition at a molecular level, despite the long analysis time and the need for a wet chemical pretreatment. Both procedures were applied to characterize the organic material present as coatings in Roman and Egyptian amphorae. DE-MS successfully identified abietanic compounds, hence a diterpenic resinous material could be identified and its degree of oxidation assessed. GC/MS enabled us to identify dehydroabietic acid, 7-oxodehydroabietic acid, 15-hydroxy-7-oxodehydroabietic acid, 15-hydroxydehydroabietic acid, retene, tetrahydroretene, norabietatriene, norabietatetraene and methyl dehydroabietate. These oxidized and aromatized abietanes provided evidence that the amphorae examined were waterproofed with a pitch produced from resinous wood of plants from the Pinaceae family. The chemometric evaluation of the GC/MS data highlighted significant chemical differences between the pitches found in the two archaeological sites, basically related to differences in the production techniques of the materials and in their degradation pathways. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Indole-related Compounds Induce the Resistance to Rice Blast Fungus, Magnaporthe grisea in Barley

JOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2004
M. Ueno
Abstract When barley leaves pretreated with indole-3-acetic acid (IAA), tryptamine and tryptophan solutions at 50 ,g/ml, which did not show antifungal activity, were inoculated with Magnaporthe grisea spores 24 h after chemical pretreatments, both blast lesion and infection-hypha formations were significantly inhibited. Such resistance to M. grisea in barley was induced from 12 h after the pretreatment. In barley leaves pretreated with IAA, tryptamine and tryptophan at 50 ,g/ml, phenylalanine ammonia-lyase (PAL), peroxidase and chitinase activities were already significantly enhanced before M. grisea inoculation, when compared with that in distilled water (DW)-treated leaves as a control. In chemical-pretreated leaves, furthermore, H2O2 generation was observed by M. grisea inoculation before lesion formation, but not in DW-pretreated leaves as a control even by M. grisea inoculation. These results suggested that indole-related compounds IAA, tryptamine and tryptophan can protect barley from M. grisea as functioning as the plant activator. Studies on indole-related compounds may contribute to develop new plant activators for disease control. [source]

Evidence of physico,chemical and isotopic modifications in archaeological bones during controlled acid etching

ARCHAEOMETRY, Issue 3 2002
V. Balter
It has been repeatedly shown that palaeoecological inferences from the elemental and isotopic content of carbonate hydroxylapatite of fossil teeth and bones are unrecoverable without removing diagenetic overprinting by chemical pretreatments. Such pretreatments may in turn cause modification of the biogenic signature. In this paper, we focus upon optimal removal of Ca,bearing carbonates (mainly calcite). In order to control the progress with time of calcite dissolution, we perform leaching under vacuum, and we monitor the evolution of the pH, pCO2, ,13C of released CO2, %C, ,13C and ,18O of the remaining mineral. For a set of different Quaternary bones and teeth, mass and isotopic balances indicate that 1 hour at most is necessary for complete dissolution of calcite with an optimal conservation of carbonate hydroxylapatite. Long,lasting experiments lead to a fractionation of hydroxylapatite 18O/16O carbonates. [source]