Tephra analysis in ombrotrophic peatlands: A geochemical comparison of acid digestion and density separation techniques

Conodonts display higher specific gravity (2.84-3.10) than common minerals in sedimentary rocks. For several decades this property has been exploited to separate these microfossils from sediment residues using density separation techniques. Two heavy liquids commonly used, bromoform and tetra-bromoethane, are toxic (Sax, 1979; HaufTand Airey, 1980) and constitute a danger to human health. Tetrabromoethane is a known carcinogen (Brem et al., 1974). Both of these liquids should be abandoned in favor of nontoxic sodium polytungstate (Callahan, 1987; Merrill, 1987b; Krukowski, 1988). There are, however, some technical problems with its use because of relatively high viscosity and a tendency to recrystallize during separation. Another big disadvantage is also its price at $100 per kilogram. These problems may be considerably overcome by using polytungstate in the way described by Savage (1988).

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Biotransformation of nitrocellulose under methanogenic conditions

Water Science & Technology ◽

10.2166/wst.1996.0567 ◽

1996 ◽

Vol 34 (5-6) ◽

pp. 327-334 ◽

Cited By ~ 2

Author(s):

David L. Freedman ◽

Bryan M. Caenepeel ◽

Byung J. Kim

Keyword(s):

Biological Treatment ◽

Enrichment Culture ◽

Basal Medium ◽

Anaerobic Biodegradation ◽

Anaerobic Treatment ◽

Acid Digestion ◽

Energetic Compounds ◽

Nitrate Ester ◽

Digestion Technique ◽

Aerobic And Anaerobic

Treatment of wastewater containing nitrocellulose (NC) fines is a significant hazardous waste problem currently facing manufacturers of energetic compounds. Previous studies have ruled out the use of biological treatment, since NC has appeared to be resistant to aerobic and anaerobic biodegradation. The objective of this study was to examine NC biotransformation in a mixed methanogenic enrichment culture. A modified cold-acid digestion technique was used to measure the percentage of oxidized nitrogen (N) remaining on the NC. After 11 days of incubation in cultures amended with NC (10 g/L) and methanol (9.9 mM), the % N (w/w) on the NC decreased from 13.3% to 10.1%. The presence of NC also caused a 16% reduction in methane output. Assuming the nitrate ester on NC was reduced to N2, the decrease in CH4 represented almost exactly the amount of reducing equivalents needed for the observed decrease in oxidized N. An increase in the heat of combustion of the transformed NC correlated with the decrease in % N. There was no statistically significant decrease in % N when only NC was added to the culture, or in controls that contained only the sulfide-reduced basal medium. The biotransformed NC has a % N comparable to nonexplosive nitrated celluloses, suggesting that anaerobic treatment may be a technically feasible process for rendering NC nonhazardous.

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Novel Separation Techniques for Isolation and Purification of Fatty Acids and Oil By‐Products

Bailey's Industrial Oil and Fat Products ◽

10.1002/047167849x.bio065.pub2 ◽

2020 ◽

pp. 1-32

Author(s):

Udaya N. Wanasundara ◽

P.K. Janitha P.D. Wanasundara ◽

Fereidoon Shahidi

Keyword(s):

Fatty Acids ◽

Separation Techniques ◽

Isolation And Purification ◽

By Products

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Single institute experience with anterior and posterior component separation techniques for large ventral hernias: A retrospective review

Asian Journal of Surgery ◽

10.1016/j.asjsur.2021.07.042 ◽

2021 ◽

Author(s):

Jaini Gala ◽

Pramod Nichat ◽

Ajay Bhandarwar ◽

Nikhil Dhimole ◽

Rajeshwari Bhat ◽

...

Keyword(s):

Retrospective Review ◽

Component Separation ◽

Separation Techniques ◽

Posterior Component Separation ◽

Ventral Hernias

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A New Radiocarbon Pretreatment Method for Molluscan Shell Using Density Fractionation of Carbonates in Bromoform

Radiocarbon ◽

10.1017/s0033822200046397 ◽

2010 ◽

Vol 52 (3) ◽

pp. 1301-1311 ◽

Cited By ~ 4

Author(s):

Christopher M Russo ◽

Jennifer A Tripp ◽

Katerina Douka ◽

Thomas F G Higham

Keyword(s):

Radiocarbon Dating ◽

Separation Technique ◽

Archaeological Sites ◽

Density Fractionation ◽

Pretreatment Method ◽

Density Separation ◽

Molluscan Shell ◽

Archaeological Artifacts ◽

Organic Remains

Coastal archaeological sites that lack organic remains for radiocarbon dating are often abundant sources of molluscan shells. As a substitute for materials such as bone and charcoal, shells can be analyzed with 14C dating to determine a site's age. Despite their being convenient, non-mobile archaeological artifacts, molluscan shells are plagued by several issues, including carbonate remodeling, in which aragonite in shells is converted to calcite as predicted by thermodynamics. We present here a carbonate density separation technique that addresses the issue of carbonate remodeling. Using a density fractionation with bromoform, aragonite concentrations are enriched in shells that have undergone significant remodeling. The technique has been applied to archaeological shells and has returned dates that are younger than those previously determined for the same shells.

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A Comprehensive Review on Chemotaxonomic and Phytochemical Aspects of Homoisoflavonoids, as Rare Flavonoid Derivatives

International Journal of Molecular Sciences ◽

10.3390/ijms22052735 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2735

Author(s):

Javad Mottaghipisheh ◽

Hermann Stuppner

Keyword(s):

Plant Species ◽

Separation Techniques ◽

Comprehensive Review

Homoisoflavonoids (3-benzylidene-4-chromanones) are considered as an infrequent flavonoid class, possessing multi-beneficial bioactivities. The present study gives an overview on phytochemical aspects of homoisoflavonoids, including utilized plant species, parts, extracts, and separation techniques. Overall, these compounds have mainly been isolated and identified from bulbs and rhizomes of the plants belonging to Asparagaceae and Fabaceae families, particularly the genera of Ophiopogon, Dracaena, Scilla, Polygonatum, and Caesalpinia.

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