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Topic: Isotopic tracer

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Radioactive isotopes

	Radioactive tracer - Wikipedia, the free encyclopedia
		A radioactive tracer is a substance containing a radioactive isotope (radioisotope).
		The tracers can be used to measure the speed of chemical processes and was developed by George de Hevesy.
		The tracers are applied in autoradiography, nuclear medicine (including single photon emission computed tomography or SPECT), and positron emission tomography.
	en.wikipedia.org /wiki/Radioactive_tracer (76 words)

	ISOTOPIC TRACER (Site not responding. Last check: 2007-10-22)
		An isotope of an element, a small amount of which may be incorporated into a sample of material in order to follow the course of that element through a chemical, biological, or physical process, and thus also follow the larger sample.
		The tracer may be radioactive, in which case observations are made by measuring the radioactivity.
		Tracers also are called labels or tags, and materials are said to be labeled or tagged when radioactive tracers are incorporated in them.
	www.websters-online-dictionary.org /definition/ISOTOPIC+TRACER (505 words)

	GLOSSARY (Site not responding. Last check: 2007-10-22)
		The tracer is quantified by measuring the amount of light emitted by the tracer at a specific wavelength after exciting the tracer with incident light of a shorter wavelength.
		The tracer, substrate, and buffer measured in the tracer activity samples are taken from the same sources that are used for the rest of the same assay run.
		Isotopic tracer activity samples contain the same amount of tracer that is added to each assay sample and are therefore higher in activity than any other sample.
	www.brendan.com /Glossary.htm (11001 words)

	Information Handout: Radiogenic Isotopes and the Eastern Mineral Resources Program of the USGS
		Isotopes used for age determinations include radiogenic Sr (strontium produced by decay of radioactive rubidium), Nd (neodymium from decay of samarium), and Os (osmium from decay of rhenium); application of all radiogenic systems requires knowledge of the appropriate half-lives and chemical analyses to detect the relative abundances of parents and daughters.
		Isotopic dating is useful for all types of rocks having a closed system -- geologists assume that the age is an estimate of the time elapsed since the radioactive parent became part of the rock or mineral and that no parent elements or daughter products have been added or lost.
		Isotopic tracer studies on sulfide minerals seek to establish constraints on the possible sources of the metals and on the contributions of different types of mineralizing fluids.
	pubs.usgs.gov /info/ayuso2 (2256 words)

	Nat' Academies Press, Emerging Technologies for Nutrition Research: Potential for Assessing Military Performance ...
		Now, except for enriched stable isotopic forms of the mineral elements, which remain in short supply and are prohibitively expensive, the stable isotopes of carbon, hydrogen, nitrogen, and oxygen and a wide variety of biochemicals containing these nuclides are commercially available in relative abundance.
		An established approach to this problem is to inject an appropriate tracer into the accessible compartment and monitor the dilution of the tracer in the accessible pool by sampling the compartment repeatedly after introduction of the tracer.
		The shape of the tracer dilution curve is determined by the characteristics of the tracer outflow into the inaccessible compartments and the nature of the unlabeled substrate movement into the accessible compartment—in other words, by the structure of the system in question.
	www.nap.edu /books/0309057973/html/201.html (4505 words)

	Isotopic tracer composition and method for making and using same - Patent 5208007
		The isotopic tracer composition comprises a protein carrier agent such as fibrinogen, antibodies, enzymes or portions thereof, bound to a radioisotope which has been reduced to a lower oxidation state by stannous phosphate at a pH of greater than 7.
		Accordingly, the present invention comprises a method for preparing an isotopic tracer composition comprising a protein or fragment thereof and a radioisotope characterized by the ability to bind a protein or fragment thereof when reduced to a lower oxidation state by a sufficient amount of stannous phosphate.
		Following administration of the isotopic tracer solution, the subject preferably is placed before a scintigraphic camera to detect the gamma radiation emitted from the target area.
	www.freepatentsonline.com /5208007.html (4435 words)

	[T] TERMS & DEFINITIONS IN NUCLEAR CHEMISTRY
		TRACER, INTRINSIC An isotope, present naturally in a given sample, that may be used to trace a given element through chemical and physical processes.
		TRACER, ISOTOPIC A tracer which only differs in isotopic composition from the substance to be traced.
		TRACER, SPECIFICALLY LABELED A tracer in which the label is present in a specified position.
	www.radiochemistry.org /nomenclature/t.htm (761 words)

	Radiogenic Isotopes - TIMS
		Isotope research techniques are exceptionally powerful tools in essential baseline regional and local mapping studies as well as resource, hazard, environmental, surficial, and global change studies.
		Radiogenic isotopic tracers (Pb, Sr, Nd, Sr, U) can be used to provide information regarding geologic processes such as magma evolution, sources of magmas and sediments, eolian dust transport, sources of metals (human-caused or natural in various ecosystems), and ñbaselineî data for environmentally pristine ecosystems.
		Isotopic data improved the understanding of the life cycle of metals and nutrients in sedimentary basins which will improve assessments of (1) mineral and energy resources, (2) environmental consequences of mining and oil petroleum, and (3) their biologic and environmental effects.
	crustal.usgs.gov /projects/isotope_geochron_labs/task2.html (1005 words)

	McGraw-Hill AccessScience: Radiochemistry
		The widespread use of isotopes in chemistry is based on two fundamental properties exhibited by all radioactive substances.
		The first property is that the disintegration rate of an isotopic sample is directly proportional to the number of radioactive atoms in the sample.
		The second fundamental property is that the disintegration rate is completely unaffected by the chemical form of the isotope, and conversely, the property of radioactivity does not affect the chemical properties of the isotope.
	www.accessscience.com /Encyclopedia/5/56/Est_569500_frameset.html (299 words)

	David Noone Research
		One way to gain insight to the dynamics of water is to investigate, with measurements and models, the isotopic composition of the water in the many places it is found.
		tracer: A foreign substance mixed with or attached to a given substance to enable the distribution or location of the latter to be determined subsequently.
		(iii) An isotopic tracer is a unique isotope, either radioactive or an enriched, uncommon stable isotope, of the element to be traced;...
	paos.colorado.edu /~dcn/research.php (275 words)

	Stable Isotope Ratio Analysis (Site not responding. Last check: 2007-10-22)
		Whether you apply stable isotopes to agriculture, archaeology, ecology, food authenticity, geochemistry or medical research we can provide you with a quality assured service, in good time and at a competitive price.
		Isotope analyses which are specific to a particular discipline can be found by application.
		If you operate an isotope ratio mass spectrometer for hydrogen, carbon, nitrogen, oxygen or sulfur analysis, you may be interested in our IRMS services.
	www.iso-analytical.com (214 words)

	Elemental and isotopic abundances (from isotope) -- Encyclopædia Britannica
		Two isotopes of an element are different in weight but not in gross chemical properties, which are determined by the number of electrons.
		An isotopic tracer must behave as does the material being studied, but, in addition, it must have some distinguishing property by which it can be detected in the...
		The procedure involves adding to a substance a known quantity of a radioisotope of the element to be measured and mixing it with the stable isotope of the element.
	www.britannica.com /eb/article-48252?tocId=48252 (866 words)

	Glossary: I-J-K
		The isotopes of an element are identical in chemical properties, and in all physical properties except those determined by the mass of the atom.
		The different isotopes of an element contain different numbers of neutrons in their nuclei.
		Isotopic tracers make it possible to determine the provenance of certain molecules in a chemical compound and to monitor the movement of chemical substances on a large scale.
	www.qc.ec.gc.ca /csl/glo/glo005_e.html (154 words)

	Isotopic tracer composition and method for making and using same - Patent 5455021
		A method for preparing an isotopic tracer composition comprising a protein or fragment thereof and a radioisotope characterized by the ability to bind a protein or fragment thereof when treated with a sufficient amount of stannous phosphate, consisting of the steps of:
		Isotopic tracer compositions are used in the diagnosis and treatment of disease states.
		The radioisotope is present in an amount to effectively bind the quantity of protein or protein fragment needed for the intended application of the isotopic tracer composition.
	www.freepatentsonline.com /5455021.html (4266 words)

	h41e in fm04
		Mass and isotope balances showed that circa 70 percent of the applied K2SO4 had passed the mineral soil horizons in 20 cm depth 2.5 years after tracer application, but no labeled sulfate was detected in seepage water in 100 cm soil depth during the observation period.
		Isotope ratio measurements on various sulfur compounds from soil samples obtained in 1991, 1995, 1999 and 2003 confirmed that the majority of the labeled sulfate was retained in the mineral soil for several years.
		Second, isotopic results recently published indicate that 10% of the nitrate observed at baseflow is direct throughput of atmospherically derived nitrate and during storm events nearly 40% of exported nitrate is throughput of atmospheric nitrate.
	www.agu.org /cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm04&database=/data/epubs/wais/indexes/fm04/fm04&maxhits=200&="H41E" (2742 words)

	MSN Encarta - Search Results - Isotopic Tracer
		MSN Encarta - Search Results - Isotopic Tracer
		Isotopic Tracer, name applied to an atom of an isotope used to observe the movement of certain materials in chemical, biological, or physical...
		In the centrifuge method the apparatus is so arranged that vapor flows downward in the outer part of the rotating cylinder and upward in the central...
	ca.encarta.msn.com /Isotopic_Tracer.html (99 words)

	Comparison of estimates of zinc absorption in humans by using 4 stable isotopic tracer methods and compartmental ...
		isotopic tracers of zinc, 1 oral and 1 intravenous.
		Stable isotopic tracers are useful for measuring mineral absorption.
		of the orally and intravenously administered tracers in plasma.
	www.ajcn.org /cgi/content/full/71/2/523 (4695 words)

	Isotopic tracer -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-22)
		An isotopic tracer, (also "isotopic marker" or "isotopic label"), is
		(One of two or more atoms with the same atomic number but with different numbers of neutrons) isotope.
		isotopes based on the different masses resulting from the different number
	www.absoluteastronomy.com /encyclopedia/i/is/isotopic_tracer.htm (415 words)

	Isotopic tracer techniques for studying the bioavailability and bioefficacy of dietary carotenoids, particularly ...
		Isotopic tracer techniques for studying the bioavailability and bioefficacy of dietary carotenoids, particularly {beta}-carotene, in humans: a review -- van Lieshout et al.
		Because retinol excretion in urine is increased in infection,
		of the estimate of isotopic enrichment and decreasing the precision
	www.ajcn.org /cgi/content/full/77/1/12 (8836 words)

	David Noone publications (Site not responding. Last check: 2007-10-22)
		Noone, D., and I. Simmonds, 2001: GCM study of synoptic influences on the isotope record in Antarctic ice cores.
		Noone, D., 2003: Water isotopes in CCSM for studying water cycles in the climate system.
		Noone, D., 2002: Isotopic tracers in detection of changes in high latitude carbon cycling, Atmospheric Chemistry Division, NASA Jet Propulsion Laboratory, Pasadena, California.
	www.gps.caltech.edu /~dcn/noonerefs.html (1477 words)

	JAWMA Paper: Feasibility of Applying a Stable Isotopic Tracer for Direct Determination of Dry Particulate Deposition to ... (Site not responding. Last check: 2007-10-22)
		A stable rare-earth isotopic tracer was used to measure the deposition of KNO 3 particles on soybean leaves by direct measurement of the tracer on the plant surfaces by thermal-ionization mass spectrometry.
		Submicrometer particles, made from a solution containing 3 mg mL -1 neodymium isotope (148 Nd, 87.9%) and 1,000 mg mL -1 KNO 3, were dispersed with a two-fluid nozzle and released upwind of a soybean field.
		As little as 5.5 pg of the tracer (i.e., excess 148 Nd) was detected in soybean leaves at signal-to-noise ra-tios ranging from 7,500 to 240,000, in the presence of 200 to 2,700 pg of naturally occurring Nd.
	www.awma.org /Journal/ShowAbstract.asp?Year=1998&PaperID=755 (284 words)

	Mendenhall Postdoctoral Research Fellowship Program: Research Opportunities
		The large range in natural isotopic compositions makes Pb a powerful tracer for understanding the sources of parental magmas of igneous rocks, origins of metals in mineral deposits, and pathways of anthropogenic contaminants.
		Pb isotopes during growth of a crystal, shell, tooth, or fossil.
		The technique has been applied to the isotopic characterization of volcanic glass particles, feldspar crystals in rocks and pottery, pyrite crystals in disseminated gold deposits, fine-scale growth zoning of galena crystals, and enamel layers of walrus teeth.
	geology.usgs.gov /postdoc/2005/opps/opp22.html (660 words)

	Targeting Malnutrition - Isotopic Tools for Evaluating Nutrition Worldwide
		Several new, more accurate isotopic tracer methods are now being developed for assessing human vitamin A status and assessing the bioavailability of provitamin A carotenoids.
		An IAEA programme was launched in 1995 to develop and modify isotopic techniques for measuring whole body vitamin A under conditions of supplementation (Ghana, Peru), food fortification (Peru, Israel) and dietary improvement (China, Thailand, Philippines, India).
		The IAEA is providing isotopes, experts in isotopic techniques, and isotopic analysis for measurement vitamin A status in infants.
	www.iaea.org /Publications/Booklets/Malnutrition/two.html (716 words)

	Fractional Protein Synthesis Rates Measured by an Intraperitoneal Injection of a Flooding Dose of ... (Site not responding. Last check: 2007-10-22)
		the tracer free pools in plasma and tissues are similar (18).
		Patterson, B. (1997) Use of stable isotopically labeled tracers for studies of metabolic kinetics: an overview.
		Wolfe, R. (1992) Radioactive and Stable Isotope Tracers in Biomedicine: Principles and Practice of Kinetic Analysis 1992 Wiley-Liss New York, NY.
	www.nutrition.org /cgi/content/full/134/10/2722 (4389 words)

	Ecology: Nitrogen Flow Through The Food Web In The Oligohaline Zone Of A New England Estuary
		Maximum tracer enrichments were lower in the grass shrimp and mud crab than in the amphipod (Fig.
		Peak tracer incorporation by oligochaetes was delayed 3 wk relative to that of benthic diatoms (Figs.
		Two contrasting spatial patterns of [N.sup.15]-tracer enrichment in biota were observed: (1) a spatial gradient of enrichment, with tracer content increasing toward the head of the estuary, and (2) enrichment with relatively little spatial variation.
	www.findarticles.com /p/articles/mi_m2120/is_2_81/ai_60138144/pg_4 (1197 words)

	USGS -- Scientific Capabilities - Geochronology, Geochemistry, and Tracer Studies
		The Geologic Division maintains a variety of high quality, state-of-the-art facilities that provide geochronological, geochemical, and isotopic tracer studies applied to both natural and artificial systems.
		Instruments and scientific staff are housed across the country in the major centers and are variably utilized according to programmatic and project priorities.
		The critical operative in these studies is the time-space framework established through careful geologic mapping, observations, and sampling (framework), coupled with isotopic tracer and geochronologic investigations.
	geology.cr.usgs.gov /capabilities/geotrac.html (233 words)

	Isotopic tracer - Wikipedia, the free encyclopedia
		In this technique, one or more of the atoms of the molecule of interest is substituted for an atom of the same chemical element, but of a different (often radioactive, such as in radioactive tracing) isotope.
		The radiation emitted by compounds containing the radioactive isotopes darkens a piece of photographic film, recording the position of these compounds relative to one another in the gel.
		This page was last modified 23:12, 15 October 2005.
	www.wikipedia.org /wiki/Isotopic_tracer (264 words)

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