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1

The Role of Naturally Occurring Stable Isotopes in Mass Spectrometry, Part II: The Instrumentation  

PubMed Central

In the second instalment of this tutorial, the authors explain the instrumentation for measuring naturally occurring stable isotopes, specifically the magnetic sector mass spectrometer. This type of instrument remains unrivalled in its performance for isotope ratio mass spectrometry (IRMS) and the reader is reminded of its operation and its technical advantages for isotope measurements. PMID:23772101

Bluck, Les; Volmer, Dietrich A.

2013-01-01

2

Correction of MS data for naturally occurring isotopes in isotope labelling experiments.  

PubMed

Mass spectrometry (MS) in combination with isotope labelling experiments is widely used for investigations of metabolism and other biological processes. Quantitative applications-e.g., (13)C metabolic flux analysis-require correction of raw MS data (isotopic clusters) for the contribution of all naturally abundant isotopes. This chapter describes how to perform such correction using the software IsoCor. This flexible, user-friendly software can be used to exploit any isotopic tracer, from well-known ((13)C, (15)N, (18)O, etc.) to unusual ((57)Fe, (77)Se, etc.) isotopes. It also provides options-e.g., correction for the isotopic purity of the tracer-to improve the accuracy of quantitative isotopic studies, and allows automated correction of large datasets that can be collected with modern MS methods. PMID:25178792

Millard, Pierre; Letisse, Fabien; Sokol, Serguei; Portais, Jean-Charles

2014-01-01

3

The Role of Naturally Occurring Stable Isotopes in Mass Spectrometry, Part I: The Theory  

PubMed Central

In this tutorial, the authors explain how naturally occurring stable isotopes are contributing to experimentally determined mass spectra and how this information can be exploited in quantitative experiments, structural elucidation studies and tracer methodologies. The first instalment of this two part series focuses on the theoretical aspects of stable isotopes and the calculation of their distribution patterns. PMID:23772100

Bluck, Les; Volmer, Dietrich A.

2013-01-01

4

APPLICATION OF THE NATURALLY-OCCURRING DEUTERIUM ISOTOPE TO TRACING THE CAPILLARY FRINGE  

EPA Science Inventory

Naturally-occurring deuterium is a useful tracer of subsurface hydrologic processes. A possible application includes the identification of capillary fringes in the vadose zone. Multiple and discontinuous water tables persist in many temperate regions, under various hydrogeologi...

5

BIODEGRADATION - MONITORED NATURAL ATTENUATION (MNA) FOR OXYGENATES: HOW IT EVOLVED, WHY IT OCCURS AND STABLE ISOTOPES  

EPA Science Inventory

The organisms that degrade MtBE under anaerobic conditions are evolved to acquire energy for growth by using molecular hydrogen and carbonate ion to cleave methyl ether bonds. Methyl ether bonds are common in nature and the bond also occurs in MTBE. MTBE in contaminated ground...

6

Compilation of minimum and maximum isotope ratios of selected elements in naturally occurring terrestrial materials and reagents  

USGS Publications Warehouse

Documented variations in the isotopic compositions of some chemical elements are responsible for expanded uncertainties in the standard atomic weights published by the Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry. This report summarizes reported variations in the isotopic compositions of 20 elements that are due to physical and chemical fractionation processes (not due to radioactive decay) and their effects on the standard atomic weight uncertainties. For 11 of those elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, copper, and selenium), standard atomic weight uncertainties have been assigned values that are substantially larger than analytical uncertainties because of common isotope abundance variations in materials of natural terrestrial origin. For 2 elements (chromium and thallium), recently reported isotope abundance variations potentially are large enough to result in future expansion of their atomic weight uncertainties. For 7 elements (magnesium, calcium, iron, zinc, molybdenum, palladium, and tellurium), documented isotope-abundance variations in materials of natural terrestrial origin are too small to have a significant effect on their standard atomic weight uncertainties. This compilation indicates the extent to which the atomic weight of an element in a given material may differ from the standard atomic weight of the element. For most elements given above, data are graphically illustrated by a diagram in which the materials are specified in the ordinate and the compositional ranges are plotted along the abscissa in scales of (1) atomic weight, (2) mole fraction of a selected isotope, and (3) delta value of a selected isotope ratio. There are no internationally distributed isotopic reference materials for the elements zinc, selenium, molybdenum, palladium, and tellurium. Preparation of such materials will help to make isotope ratio measurements among laboratories comparable. The minimum and maximum concentrations of a selected isotope in naturally occurring terrestrial materials for selected chemical elements reviewed in this report are given below: Isotope Minimum mole fraction Maximum mole fraction -------------------------------------------------------------------------------- 2H 0 .000 0255 0 .000 1838 7Li 0 .9227 0 .9278 11B 0 .7961 0 .8107 13C 0 .009 629 0 .011 466 15N 0 .003 462 0 .004 210 18O 0 .001 875 0 .002 218 26Mg 0 .1099 0 .1103 30Si 0 .030 816 0 .031 023 34S 0 .0398 0 .0473 37Cl 0 .240 77 0 .243 56 44Ca 0 .020 82 0 .020 92 53Cr 0 .095 01 0 .095 53 56Fe 0 .917 42 0 .917 60 65Cu 0 .3066 0 .3102 205Tl 0 .704 72 0 .705 06 The numerical values above have uncertainties that depend upon the uncertainties of the determinations of the absolute isotope-abundance variations of reference materials of the elements. Because reference materials used for absolute isotope-abundance measurements have not been included in relative isotope abundance investigations of zinc, selenium, molybdenum, palladium, and tellurium, ranges in isotopic composition are not listed for these elements, although such ranges may be measurable with state-of-the-art mass spectrometry. This report is available at the url: http://pubs.water.usgs.gov/wri014222.

Coplen, T.B.; Hopple, J.A.; Böhlke, J.K.; Peiser, H.S.; Rieder, S.E.; Krouse, H.R.; Rosman, K.J.R.; Ding, T.; Vocke, R.D., Jr.; Revesz, K.M.; Lamberty, A.; Taylor, P.; De Bievre, P.

2002-01-01

7

The Role of Naturally Occurring Stable Isotopes in Mass Spectrometry, Part III: Small Gas Molecule Calculations  

PubMed Central

In the third instalment of this tutorial, the authors explain the determination of the isotopic composition of a sample from a mass spectrometric measurement, and the methods of calculation as well as the units used. This tutorial outlines the practices in common usage, so that researchers new to this field can obtain a good understanding of the fundamentals involved. PMID:23766554

Bluck, Les; Volmer, Dietrich A.

2013-01-01

8

Characterising the exchangeability of phenanthrene associated with naturally occurring soil colloids using an isotopic dilution technique.  

PubMed

The association of polycyclic aromatic hydrocarbons (PAHs) with inorganic and organic colloids is an important factor influencing their bioavailability, mobility and degradation in the environment. Despite this, our understanding of the exchangeability and potential bioavailability of PAHs associated with colloids is limited. The objective of this study was to use phenanthrene as a model PAH compound and develop a technique using (14)C phenanthrene to quantify the isotopically exchangeable and non-exchangeable forms of phenanthrene in filtered soil water or sodium tetraborate extracts. The study was also designed to investigate the exchangeability of colloidal phenanthrene as a function of particle size. Our findings suggest that the exchangeability of phenanthrene in sodium tetraborate is controlled by both inorganic and organic colloids, while in aqueous solutions inorganic colloids play the dominant role (even though coating of these by organic matter cannot be excluded). Filter pore size did not have a significant effect on phenanthrene exchangeability. PMID:25689461

Tavakkoli, Ehsan; Juhasz, Albert; Donner, Erica; Lombi, Enzo

2015-04-01

9

New insight into biomarkers of human mercury exposure using naturally occurring mercury stable isotopes.  

PubMed

Human exposure to methylmercury (MeHg) and elemental mercury vapor (Hg(0)(g)) are often estimated using total Hg concentrations in hair and urine, respectively. We investigated whether Hg stable isotopes could be used to better distinguish between exposure to Hg(0)(g) versus MeHg. We found that hair from North American dental professionals was characterized by high positive ?(199)Hg values (mean = 1.86‰, 1 SD = 0.12‰, n = 11). This confirms that among people who regularly consume fish, total Hg concentrations in hair reflect exposure to MeHg. In contrast, we found that urine from the same individuals was characterized by a range of ?(199)Hg values (0.29 to 1.77‰, 2 SD = 0.06‰, n = 12) that were significantly correlated to the number of dental amalgams in each individual's mouth. We hypothesize that fish-derived MeHg is demethylated within the body, causing mass-dependent fractionation and the excretion of inorganic Hg in urine. Mercury in urine therefore represents a mixture of demethylated fish-derived MeHg and amalgam-derived inorganic Hg. We estimate that the majority (>70%) of Hg in urine from individuals with <10 dental amalgams is derived from ingestion of MeHg in fish. These data suggest that within populations that consume fish, urine total Hg concentrations may overestimate Hg exposure from personal dental amalgams. PMID:23463943

Sherman, Laura S; Blum, Joel D; Franzblau, Alfred; Basu, Niladri

2013-04-01

10

Analysis of Long-Term Diet Changes in Tropical Seabirds Using Naturally Occurring Stable Isotopes  

NASA Astrophysics Data System (ADS)

A clear understanding of ecosystem response to past environmental changes will provide more accurate interpretations of current ecosystem trends. With this mindset, we investigated the effects of the 1976/77 regime shift in the Pacific Ocean on a tropical pelagic community of apex predators. Using study skins from museum collections from 1960 to 2006, we measured stable carbon (?13C) and nitrogen (?15N) isotopes for a suite of ecologically and phylogenetically diverse seabirds from the eastern Pacific warm pool. In this region, seabirds generally forage by depending on subsurface predators to drive prey to the surface or by associating with oceanographic features that increase productivity or aggregate prey in space and time. We found that annual ?15N means from Sooty Terns’ (Onychoprion fuscatus) feathers decreased by 2.98‰, while all other species did not show any significant trends over the study period. Annual ?13C means from feathers of Sooty Terns, Wedge-tailed Shearwaters (Puffinus pacificus), Red-footed Boobies (Sula sula) and Juan Fernandez Petrels (Petrodroma externa) decreased by an average of 1.02‰, at rates between 0.01 and 0.02 ?13C‰ per year-1. Our results do not suggest a response of the seabird community to the 1976/77 regime shift. Instead, they are consistent with a trophic shift and/or change in foraging area for Sooty Terns and a long-term decrease in feather ?13C for the eastern Pacific warm pool seabird community. This long-term decrease in feather ?13C is most likely due to the Suess effect and less likely due to a decline in primary productivity of the system. We hypothesize that a deepening trend in thermocline depth in the eastern Pacific warm pool affected Sooty Terns more than other species in the subsurface predator-dependent guild that depend less on smaller subsurface predators like skipjack tuna.

Vilchis, I.; Ballance, L.

2010-12-01

11

"Naturally occurring asbestos  

NASA Astrophysics Data System (ADS)

The term asbestos refers to six silicate minerals from amphibole and serpentine groups. By definition, it consists in bundles of thin and flexible long fibers, with high-tensile strength, and chemical and heat resistance. In contrast to asbestos found within commercial products and mining, the specific term ''naturally occurring asbestos'' (NOA) refers to asbestiform minerals occurring within rocks or soils that can be released by human activities or weathering processes. The fact that the exposure to asbestos is related to lung pathologies is now widely demonstrated (e.g. asbestosis, mesothelioma and lung cancer). However, if health risks associated with exposure to NOA exist, they are not yet well documented. The crystallization of natural asbestos occurs in specific Mg-rich lithologies associated with peculiar structural and metamorphic conditions. By recognizing and combining such specific geologic criteria, the presence or the absence of asbestos in bedrock terrains can be reasonably predicted and maps of NOA hazard can be drawn. We present here new results of geological mapping and petrological study concerning the evaluation of the NOA hazard in the Alps and Corsica, in France. The three folds approach consists in (1) a determination of lithologies with potential NOA from a bibliographic compilation and extraction of target zones from a geological geodatabase (2) a geological mapping of the target zones followed by a petrological characterization of sampled asbestiform minerals in the laboratory (optical microscopy, TEM, SEM, and Raman spectroscopy technics), and (3) the drawing of the final map of NOA hazard, at regional-scale. Occurrence criteria can be retained as follows: 1. NOA are abundant in the internal zones of the Alps and Corsica, especially within ophiolitic complexes. Natural asbestos are mostly concentrated within ultramafic rocks but can also occur within basic lithologies such as Mg-metagabbros, metabasalts and meta-pillow-lavas, 2. Asbestos is commonly located within fractures, shear-bands or shear-planes, developed during late retrograde metamorphic history, 3. Tremolite-actinolite-type asbestos is abundant both in ultramafic and mafic rocks, 4. Natural asbestos occur in few places within the external zones of the Alps, especially within hercynian ophiolitic massifs or concentrated in late Alpine fractures affecting leptyno-amphibolic lithologies.

Cagnard, F.; Lahondère, D.; Blein, O.; Lahfid, A.; Wille, G.

2012-04-01

12

Isotopic Composition and Origin of Indigenous Natural Perchlorate and Co-Occurring Nitrate in the Southwestern United States  

SciTech Connect

Perchlorate (ClO4-) has been detected over an expansive area in groundwater and soils in the southwestern United States. Because of its wide distribution, much of the ClO4- is presumed to be from natural sources, primarily atmospheric deposition and accumulation. The objective of this study was to evaluate the range of the isotopic composition of natural ClO4- indigenous to the southwestern U.S. Stable isotope ratios of Cl and O were determined for ClO4- collected from numerous sources, including: groundwater from several locations in the southern high plains (SHP) of Texas and New Mexico and the middle Rio Grande Basin in New Mexico, vadose zone soil from the SHP, and surface NO3--rich caliches from four locations in Death Valley, CA. The data suggest that natural ClO4- in the southwestern U.S. has at least two distinctive isotope signatures that differ both from each other and from those previously reported for natural ClO4- from the Atacama Desert of Chile and all anthropogenic ClO4- sources tested to date. The ClO4- in four caliche samples collected in Death Valley has high 17O values (8.6 to 18.4 ), similar to those described for ClO4- from the Atacama, and suggesting atmospheric formation via reaction with ozone (O3). However, the Death Valley samples have 37Cl values (-3.1 to -0.8 ) and 18O values (+2.9 to +26.1 ), that are appreciably higher than Atacama perchlorate ( 37Cl; -14.3 to -10.2 and 18O; (-10.5 to -2.2 , respectively). In contrast, samples from 8 locations in West Texas and New Mexico were characterized by only a slight elevation in 17O (0.3 to 1.3 ), suggesting either that this material is not primarily generated with O3 as a reactant or that the ClO4- has been consistently altered post-deposition by one or more processes that caused isotopic exchange of O. The 37Cl values in the SHP perchlorate (+ 3.4 to + 5.1 ) were consistently higher than for the Atacama or Death Valley salts, while the 18O values (+ 0.5 to + 4.8 ) overlapped significantly with those from Death Valley. Additional studies are necessary to better understand the various origins and potential exchange reactions of natural perchlorate, however, the data presented herein provide constraints on natural isotope signatures important for interpretation of isotope values at locations in which ClO4- sources in groundwater or drinking water are unknown.

Jackson, Andrew [Texas Tech University, Lubbock; Bohlke, J. K. [U.S. Geological Survey, Reston, VA; Gu, Baohua [ORNL; Hatzinger, Paul B. [Shaw Environmental, Inc., Lawrenceville, NJ; Sturchio, N. C. [University of Illinois, Chicago

2010-01-01

13

Naturally Occurring Food Toxins  

PubMed Central

Although many foods contain toxins as a naturally-occurring constituent or, are formed as the result of handling or processing, the incidence of adverse reactions to food is relatively low. The low incidence of adverse effects is the result of some pragmatic solutions by the US Food and Drug Administration (FDA) and other regulatory agencies through the creative use of specifications, action levels, tolerances, warning labels and prohibitions. Manufacturers have also played a role by setting limits on certain substances and developing mitigation procedures for process-induced toxins. Regardless of measures taken by regulators and food producers to protect consumers from natural food toxins, consumption of small levels of these materials is unavoidable. Although the risk for toxicity due to consumption of food toxins is fairly low, there is always the possibility of toxicity due to contamination, overconsumption, allergy or an unpredictable idiosyncratic response. The purpose of this review is to provide a toxicological and regulatory overview of some of the toxins present in some commonly consumed foods, and where possible, discuss the steps that have been taken to reduce consumer exposure, many of which are possible because of the unique process of food regulation in the United States. PMID:22069686

Dolan, Laurie C.; Matulka, Ray A.; Burdock, George A.

2010-01-01

14

Isotopic composition and origin of indigenous natural perchlorate and co-occurring nitrate in the southwestern United States  

USGS Publications Warehouse

Perchlorate (ClO4?) has been detected widely in groundwater and soils of the southwestern United States. Much of this ClO4? appears to be natural, and it may have accumulated largely through wet and dry atmospheric deposition. This study evaluates the isotopic composition of natural ClO4? indigenous to the southwestern U.S. Stable isotope ratios were measured in ClO4? (?18O, ?17O, ?37Cl) and associated NO3? (?18O, ?17O, ?15N) in groundwater from the southern High Plains (SHP) of Texas and New Mexico and the Middle Rio Grande Basin (MRGB) in New Mexico, from unsaturated subsoil in the SHP, and from NO3?-rich surface caliche deposits near Death Valley, California. The data indicate natural ClO4? in the southwestern U.S. has a wide range of isotopic compositions that are distinct from those reported previously for natural ClO4? from the Atacama Desert of Chile as well as all known synthetic ClO4?. ClO4? in Death Valley caliche has a range of high ?17O values (+8.6 to +18.4 ‰), overlapping and extending the Atacama range, indicating at least partial atmospheric formation via reaction with ozone (O3). However, the Death Valley ?37Cl values (?3.1 to ?0.8 ‰) and ?18O values (+2.9 to +26.1‰) are higher than those of Atacama ClO4?. In contrast, ClO4? from western Texas and New Mexico has much lower ?17O (+0.3 to +1.3‰), with relatively high ?37Cl (+3.4 to +5.1 ‰) and ?18O (+0.5 to +4.8 ‰), indicating either that this material was not primarily generated with O3 as a reactant or that the ClO4? was affected by postdepositional O isotope exchange. High ?17O values in ClO4? (Atacama and Death Valley) are associated with high ?17O values in NO3?, indicating that both compounds preserve characteristics of O3-related atmospheric production in hyper-arid settings, whereas both compounds have low ?17O values in less arid settings. Although ?17O variations in terrestrial NO3? can be attributed to mixing of atmospheric (high ?17O) and biogenic (low ?17O) NO3?, variations in ?17O of terrestrial ClO4? are not readily explained in the same way. This study provides important new constraints for identifying natural sources of ClO4? in different environments by multicomponent isotopic characteristics, while presenting the possibilities of divergent ClO4? formation mechanisms and(or) ClO4? isotopic exchange in biologically active environments.

Jackson, W. Andrew; Böhlke, John Karl; Gu, Baohua; Hatzinger, Paul B.; Sturchio, Neil C.

2010-01-01

15

Isotopic composition and origin of indigenous natural perchlorate and co-occurring nitrate in the southwestern United States.  

PubMed

Perchlorate (ClO(4)(-)) has been detected widely in groundwater and soils of the southwestern United States. Much of this ClO(4)(-) appears to be natural, and it may have accumulated largely through wet and dry atmospheric deposition. This study evaluates the isotopic composition of natural ClO(4)(-) indigenous to the southwestern U.S. Stable isotope ratios were measured in ClO(4)(-) (delta(18)O, Delta(17)O, delta(37)Cl) and associated NO(3)(-) (delta(18)O, Delta(17)O, delta(15)N) in groundwater from the southern High Plains (SHP) of Texas and New Mexico and the Middle Rio Grande Basin (MRGB) in New Mexico, from unsaturated subsoil in the SHP, and from NO(3)(-)-rich surface caliche deposits near Death Valley, California. The data indicate natural ClO(4)(-) in the southwestern U.S. has a wide range of isotopic compositions that are distinct from those reported previously for natural ClO(4)(-) from the Atacama Desert of Chile as well as all known synthetic ClO(4)(-). ClO(4)(-) in Death Valley caliche has a range of high Delta(17)O values (+8.6 to +18.4 per thousand), overlapping and extending the Atacama range, indicating at least partial atmospheric formation via reaction with ozone (O(3)). However, the Death Valley delta(37)Cl values (-3.1 to -0.8 per thousand) and delta(18)O values (+2.9 to +26.1 per thousand) are higher than those of Atacama ClO(4)(-). In contrast, ClO(4)(-) from western Texas and New Mexico has much lower Delta(17)O (+0.3 to +1.3 per thousand), with relatively high delta(37)Cl (+3.4 to +5.1 per thousand) and delta(18)O (+0.5 to +4.8 per thousand), indicating either that this material was not primarily generated with O(3) as a reactant or that the ClO(4)(-) was affected by postdepositional O isotope exchange. High Delta(17)O values in ClO(4)(-) (Atacama and Death Valley) are associated with high Delta(17)O values in NO(3)(-), indicating that both compounds preserve characteristics of O(3)-related atmospheric production in hyper-arid settings, whereas both compounds have low Delta(17)O values in less arid settings. Although Delta(17)O variations in terrestrial NO(3)(-) can be attributed to mixing of atmospheric (high Delta(17)O) and biogenic (low Delta(17)O) NO(3)(-), variations in Delta(17)O of terrestrial ClO(4)(-) are not readily explained in the same way. This study provides important new constraints for identifying natural sources of ClO(4)(-) in different environments by multicomponent isotopic characteristics, while presenting the possibilities of divergent ClO(4)(-) formation mechanisms and(or) ClO(4)(-) isotopic exchange in biologically active environments. PMID:20521813

Jackson, W Andrew; Böhlke, John Karl; Gu, Baohua; Hatzinger, Paul B; Sturchio, Neil C

2010-07-01

16

Caffeine, a naturally occurring acaricide.  

PubMed

Since caffeine is a plant alkaloid that has been described as a naturally occurring insecticide, its acaricidal effect on Dermatophagoides pteronyssinus (Dp) was investigated. Twelve cultures were established by adding 30 Dp to 200 mg of Tetramin fish food and brewer's yeast (8:2 ratio); six cultures were treated with 20 mg of finely ground caffeine. All 12 cultures were incubated at 75% relative humidity, 25 degrees C, and observed during 8 weeks. Live mites were then counted under a stereoscope, cultures were extracted, and supernatants were analyzed for Der p I and Der f I allergen content with a two-site monoclonal RIA. Live mite counts in untreated cultures varied from 146 to 274 (215 +/- 47.1), and in caffeine-treated cultures from 0 to 3 (1 +/- 1.2; p less than or equal to 0.0001). Der p I concentrations in untreated cultures varied from 588 to 9000 ng/gm (3138.3 +/- 2990.8 ng/gm), and in caffeine-treated cultures from 52 to 117 ng/gm (78 +/- 23.8 ng/gm; p less than or equal to 0.01). Der p I was not detected in the food media or caffeine; Der f I was not detected in any of the cultures. Results demonstrate that caffeine inhibits mite growth and allergen production. PMID:1991914

Russell, D W; Fernández-Caldas, E; Swanson, M C; Seleznick, M J; Trudeau, W L; Lockey, R F

1991-01-01

17

Biodegradation ? Monitored Natural Attenuation (MNA) for Oxygenates: How it Evolved, why it Occurs and Using Stable Carbon Isotopes to Predict Plume Behavior  

EPA Science Inventory

The organisms that degrade MtBE under anaerobic conditions are evolved to acquire energy for growth by using molecular hydrogen and carbonate ion to cleave methyl ether bonds. Methyl ether bonds are common in nature and the bond also occurs in MTBE. MTBE in contaminated ground...

18

The magnitude of the naturally occurring isotopic enrichment of 13C in exhaled CO2 is directly proportional to exercise intensity in humans.  

PubMed

Due to various biochemical fractionation processes during lipid synthesis, the lipid molecules in the body contain substantially lower concentrations of 13C than the nonlipid molecules. Because of the isotopic differences between these two endogenous nutrient pools, any shift toward nonlipid fuel oxidation would be expected to increase in the ?13C of the exhaled breath. Interestingly, the possibility of whether or not an exercise-induced change actually occurs has been debated in literature for over two decades and researchers have still not reached a consensus. We measured ventilatory and metabolic variables before, during, and after exercise in forty-eight adults (n = 25 females, n = 23 males; 20.1 ± 1.9 years) assigned to either a resting treatment or one of three exercising treatments where they maintained a heart rate of 130, 150, or 170 bpm for 56 min. We found that the mean metabolic rates of the exercising groups increased 4.4-fold, 6.1-fold, and 7.7-fold above resting values, respectively. Exercise caused small increases in respiratory exchange ratios (e.g., from 0.83 ± 0.08 to 0.86 ± 0.10) indicative of increased carbohydrate oxidation, but these changes were too variable to be reliably correlated with exercise intensity. In contrast, the ?13C of the exhaled breath increased by 0.62 ± 0.19‰, 1.14 ± 0.29‰, and 1.79 ± 0.50‰, respectively, for the three groups and was significantly correlated with the intensity of exercise. We also show that the isotopic difference of the lipid and nonlipids of the body is similar (~ 2.7‰) even when consuming bulk diets that are isotopically distinct (> 8‰). If not corrected for, these exercise-induced changes in ?13C of the breath would be sufficiently large to skew the results of studies investigating the oxidative fates of exogenous nutritional supplements. PMID:25446144

McCue, Marshall D; Passement, Celeste A; Rodriguez, Miranda

2015-01-01

19

Naturally occurring stable isotopes reflect changes in protein turnover and growth in gilthead sea bream (Sparus aurata) juveniles under different dietary protein levels.  

PubMed

Ideal nutritional conditions are crucial to sustainable aquaculture due to economic and environmental issues. Here we apply stable isotope analysis as an indicator of fish growth and feeding balance, to define the optimum diet for efficient growing conditions. Juveniles of gilthead sea bream were fed with six isoenergetic diets differing in protein to lipid proportion (from 41/26 to 57/20). As protein intake increased, ?¹?N and ??¹?N of muscle and ??¹?N and ??¹³C of its protein fraction decreased, indicating lower protein turnover and higher protein deposition in muscle. This is reflected in the inverse relationship found between ??¹?N and growth rate, although no differences were observed in either parameter beyond the protein/lipid proportion 47/23. Principal component analysis (PCA) also signaled 47/23 diet as the pivotal point with the highest growing efficiency, with isotopic parameters having the highest discrimination load. Thus, muscle isotope composition, especially ¹?N, can be used to evaluate nutritional status in farmed fish. PMID:23947425

Martin-Perez, Miguel; Fernandez-Borras, Jaume; Ibarz, Antoni; Felip, Olga; Fontanillas, Ramon; Gutierrez, Joaquim; Blasco, Josefina

2013-09-18

20

Naturally occurring genetic variation in Arabidopsis thaliana  

Microsoft Academic Search

Currently, genetic variation is probably the most important basic resource for plant biology. In addition to the variation artificially generated by mutants in model plants, naturally occurring genetic variation is extensively found for most species, including Arabidopsis. In many cases, natural variation present among accessions is multigenic, which has historically hampered its analysis. However, the exploitation of this resource down

Maarten Koornneef; Carlos Alonso-Blanco; Dick Vreugdenhil

2004-01-01

21

Introduction to naturally occurring radioactive material  

Microsoft Academic Search

Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. We are also bathed in a sea of natural radiation coming from the sun and deep space. Living systems have adapted to these levels

Egidi

1997-01-01

22

The problem of “naturally”occurring drought  

Microsoft Academic Search

Naturally-occurring drought is defined here to be drought arising from the nonlinear interactions which are an inherent part of the dynamics of the climatic system. As such it has no specific excitation mechanism, in contrast to forced drought where sea surface temperature anomalies are frequently cited as an important precursor. The essential difference between these two types of drought is

B G Hunt; H B Gordon

1988-01-01

23

Leaching of technologically enhanced naturally occurring radioactive materials.  

PubMed

A form of waste associated with mining activities is related to the type of deposit being mined and to the procedure of exploitation and enrichment adopted. The wastes usually contain relatively large amounts of technologically enhanced naturally occurring radioactive materials (TENORM). The TENORM are often stored on the surface. Consequently, they can be leached as a result of interaction with aqueous solutions of different chemical composition. This further leads to pollution of water and soil in the vicinity of the stored wastes. The paper presents the results of laboratory investigation aimed at quantifying the leaching process of samples originating from uranium dumps and storage reservoirs associated with brine pumped from coal mines. The leaching process was investigated with respect to selected elements: uranium isotopes, radium isotopes, iron, barium and sodium. The samples were exposed to aqueous solutions of different chemical composition. The experiments revealed that TENORM in form of sulphate compounds are the most resistant against leaching. The leaching coefficient for radium isotopes varies from a few thousandth percent to a few hundredth percent. On the other hand, for TENORM occurring in sand or sludge, the leaching coefficient for uranium and radium isotopes ranged from a few hundredth percent to a few percent. PMID:17482828

Chau, Nguyen Dinh; Chru?ciel, Edward

2007-08-01

24

Persulfate activation by naturally occurring trace minerals.  

PubMed

The potential for 13 naturally occurring minerals to mediate the decomposition of persulfate and generate a range of reactive oxygen species was investigated to provide fundamental information on activation mechanisms when persulfate is used for in situ chemical oxidation (ISCO). Only four of the minerals (cobaltite, ilmenite, pyrite, and siderite) promoted the decomposition of persulfate more rapidly than persulfate-deionized water control systems. The other nine minerals decomposed persulfate at the same rate or more slowly than the control systems. Mineral-mediated persulfate activation was conducted with the addition of one of three probe compounds to detect the generation of reactive oxygen species: anisole (sulfate+hydroxyl radical), nitrobenzene (hydroxyl radical), and hexachloroethane (reductants and nucleophiles). The reduced mineral pyrite promoted rapid generation of sulfate+hydroxyl radical. However, the remainder of the minerals provided minimal potential for the generation of reactive oxygen species. The results of this research demonstrate that the majority of naturally occurring trace minerals do not activate persulfate to generate reactive oxygen species, and other mechanisms of activation are necessary to promote contaminant destruction in the subsurface during persulfate ISCO. PMID:21968122

Teel, Amy L; Ahmad, Mushtaque; Watts, Richard J

2011-11-30

25

Introduction to naturally occurring radioactive material  

SciTech Connect

Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. We are also bathed in a sea of natural radiation coming from the sun and deep space. Living systems have adapted to these levels of radiation and radioactivity. But some industrial practices involving natural resources concentrate these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. Other activities, such as flying at high altitudes, expose us to elevated levels of NORM. This session will concentrate on diffuse sources of technologically-enhanced (TE) NORM, which are generally large-volume, low-activity waste streams produced by industries such as mineral mining, ore benefication, production of phosphate Fertilizers, water treatment and purification, and oil and gas production. The majority of radionuclides in TENORM are found in the uranium and thorium decay chains. Radium and its subsequent decay products (radon) are the principal radionuclides used in characterizing the redistribution of TENORM in the environment by human activity. We will briefly review other radionuclides occurring in nature (potassium and rubidium) that contribute primarily to background doses. TENORM is found in many waste streams; for example, scrap metal, sludges, slags, fluids, and is being discovered in industries traditionally not thought of as affected by radionuclide contamination. Not only the forms and volumes, but the levels of radioactivity in TENORM vary. Current discussions about the validity of the linear no dose threshold theory are central to the TENORM issue. TENORM is not regulated by the Atomic Energy Act or other Federal regulations. Control and regulation of TENORM is not consistent from industry to industry nor from state to state. Proposed regulations are moving from concentration-based standards to dose-based standards. So when is TENORM a problem? Where is it a problem? That depends on when, where, and whom you talk to! We will start by reviewing background radioactivity, then we will proceed to the geology, mobility, and variability of these radionuclides. We will then review some of the industrial sectors affected by TENORM, followed by a brief discussion on regulatory aspects of the issue.

Egidi, P.

1997-08-01

26

Attenuation of Naturally Occurring Arsenic at  

E-print Network

(USEPA) lowered the maximum contaminant level (MCL) for dissolved arsenic in groundwater from 0.050 mg/L to 0.010 mg/L due to long-term chronic health effects of low concentrations of arsenic in drinking water. This has heightened public and regulatory awareness of dissolved arsenic in groundwater. Arsenic occurrence at petroleum-impacted sites can be summarized by five basic principles that govern the fate and transport of arsenic in shallow aquifers impacted by petroleum hydrocarbons. These are: 1. If arsenic is not present in the site mineralogy, or if arsenic has not been emplaced due to human activity, petroleum impacts will not cause arsenic impacts to groundwater. Arsenic is not a major contaminant in petroleum hydrocarbons; 2. For sites that have naturally occurring arsenic-bearing minerals, sorbed arsenic phases, or aged anthropogenic arsenic sources, there is a stable arsenic geochemistry present that determines the ambient (background) level of dissolved arsenic in groundwater. If the background level of arsenic naturally exceeds the new MCL, then the MCL is unachievable as an attenuation or remediation goal;

Petroleum Hydrocarbon–impacted Sites; Richard A. Brown; Katrina E. Patterson

27

Naturally occurring contamination in the Mancos Shale.  

PubMed

Some uranium mill tailings disposal cells were constructed on dark-gray shale of the Upper Cretaceous Mancos Shale. Shale of this formation contains contaminants similar to those in mill tailings. To establish the contributions derived from the Mancos, we sampled 51 locations in Colorado, New Mexico, and Utah. Many of the groundwater samples were saline with nitrate, selenium, and uranium concentrations commonly exceeding 250,?000, 1000, and 200 ?g/L, respectively. Higher concentrations were limited to groundwater associated with shale beds, but were not correlated with geographic area, stratigraphic position, or source of water. The elevated concentrations suggest that naturally occurring contamination should be considered when evaluating groundwater cleanup levels. At several locations, seep water was yellow or red, caused in part by dissolved organic carbon concentrations up to 280 mg/L. Most seeps had (234)U to (238)U activity ratios greater than 2, indicating preferential leaching of (234)U. Seeps were slightly enriched in (18)O relative to the meteoric water line, indicating limited evaporation. Conceptually, major ion chemical reactions are dominated by calcite dissolution following proton release from pyrite oxidation and subsequent exchange by calcium for sodium residing on clay mineral exchange sites. Contaminants are likely released from organic matter and mineral surfaces during weathering. PMID:22225529

Morrison, Stan J; Goodknight, Craig S; Tigar, Aaron D; Bush, Richard P; Gil, April

2012-02-01

28

Antigenotoxic activity of naturally occurring furanocoumarins.  

PubMed

This study was designed to investigate the antigenotoxic effects of a series of naturally occurring furanocoumarins (NOFs) including isoimperatorin, imperatorin, (+)-oxypeucedanin, (+)-byakangelicol, and (+)-byakangelicine on antigenotoxic activities against genotoxicity induced by carcinogens [furylfuramide and N-methyl-N'-nitro-N-nitrosoguanidine], and procarcinogens 2-[2-(acetylamino)-4-amino-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-4) and 2-amino-3,4-dimethyl-3H-imidazo-[4,5-f] quinoline (MeIQ)] to genotoxic metabolites catalyzed by rat S9 or rat and human recombinant cytochrome P450 (CYP) 1As by using the umu test based on SOS response. Five different NOFs, which were found in the human diets, strongly inhibited the umuC induction by procarcinogens, but did not be affected by carcinogens. Notably, isoimperatorin and (+)-byakangelicol were found to be potent inhibitors on the metabolic activation of PBTA-4 and MeIQ to genotoxic metabolites catalyzed by rat and human CYP1A1, or rat and human CYP1A2, respectively. In addition, to elucidate the mechanism of their antigenotoxic effects against procarcinogens, the effects of NOFs on rat and human CYP1A1- or rat and human CYP1A2-related enzyme activities of 7-ethoxyresorufin-O-deethylase (EROD) were also investigated. Reduction of the EROD activities by some of the NOFs with IC(50) values of 0.23-20.64 ?M was found to be due to strong inhibition of CYP1A1 and CYP1A2 dependent monooxygenases. Furthermore, the mechanism of inhibitions by NOFs on human CYP1A1 and CYP1A2 was analyzed by means of Dixon plots plus Cornish-Bowden plots. The kinetic studies of inhibition types revealed that these compounds inhibited the human CYP1A1 and CYP1A2 a variety of modes rather than by a uniform one. Moreover, experiments with a two-stage incubation indicated that NOFs, except for imperatorin, inhibited human CYP1A1 in a mechanism-based manner, but directly inhibited human CYP1A2. This data suggest that certain NOFs, to which humans are exposed in the diet, may be capable of affecting the metabolic activation of procarcinogens due to inhibitions of CYP1A1 and CYP1A2 enzymes. PMID:21786339

Marumoto, Shinsuke; Oda, Yoshimitsu; Miyazawa, Mitsuo

2011-10-01

29

Naturally Occurring Radioactive Materials in Cargo at US Borders  

SciTech Connect

In the U.S. and other countries, large numbers of vehicles pass through border crossings each day. The illicit movement of radioactive sources is a concern that has resulted in the installation of radiation detection and identification instruments at border crossing points. This activity is judged to be necessary because of the possibility of an act of terrorism involving a radioactive source that may include any number of dangerous radionuclides. The problem of detecting, identifying, and interdicting illicit radioactive sources is complicated by the fact that many materials present in cargo are somewhat radioactive. Some cargo contains naturally occurring radioactive material or technologically-enhanced naturally occurring radioactive material that may trigger radiation portal monitor alarms. Man-made radioactive sources, especially medical isotopes, are also frequently observed and produce alarms. Such nuisance alarms can be an operational limiting factor for screening of cargo at border crossings. Information about the nature of the radioactive materials in cargo that can interfere with the detection of radionuclides of concern is necessary. This paper provides such information for North American cargo, but the information may also be of use to border control officials in other countries. (PIET-43741-TM-361)

Kouzes, Richard T.; Ely, James H.; Evans, John C.; Hensley, Walter K.; Lepel, Elwood A.; McDonald, Joseph C.; Schweppe, John E.; Siciliano, Edward R.; Strom, Daniel J.; Woodring, Mitchell L.

2006-01-01

30

Plant breeding Variation occurring after natural and  

E-print Network

evaluated in Violet de Provence and in some other early cultivars. During micropropagation, the frequency plants are undesirable, the practi- cal use of micropropagation is restricted. Analysis of the nature micropropagation, was ob- served in the Violet de Provence cultivar (Pé- caut, 1985) and was confirmed in other

Paris-Sud XI, Université de

31

Naturally-occurring pathogens and invasive insects  

Technology Transfer Automated Retrieval System (TEKTRAN)

The successful establishment of introduced pest insects has been attributed, in part, to the pest insects’ separation from natural control agents in their native ranges. This concept, i.e., the ‘enemies release hypothesis’, is commonly referenced in the literature as a mechanism that fosters invasi...

32

Thermodynamic characterization of naturally occurring RNA tetraloops  

PubMed Central

Although tetraloops are one of the most frequently occurring secondary structure motifs in RNA, less than one-third of the 30 most frequently occurring RNA tetraloops have been thermodynamically characterized. Therefore, 24 stem–loop sequences containing common tetraloops were optically melted, and the thermodynamic parameters ?H°, ?S°, ?G°37, and TM for each stem–loop were determined. These new experimental values, on average, are 0.7 kcal/mol different from the values predicted for these tetraloops using the model proposed by Vecenie CJ, Morrow CV, Zyra A, Serra MJ. 2006. Biochemistry 45: 1400–1407. The data for the 24 tetraloops reported here were then combined with the data for 28 tetraloops that were published previously. A new model, independent of terminal mismatch data, was derived to predict the free energy contribution of previously unmeasured tetraloops. The average absolute difference between the measured values and the values predicted using this proposed model is 0.4 kcal/mol. This new experimental data and updated predictive model allow for more accurate calculations of the free energy of RNA stem–loops containing tetraloops and, furthermore, should allow for improved prediction of secondary structure from sequence. It was also shown that tetraloops within the sequence 5?-GCCNNNNGGC-3? are, on average, 0.6 kcal/mol more stable than the same tetraloop within the sequence 5?-GGCNNNNGCC-3?. More systemic studies are required to determine the full extent of non-nearest-neighbor effects on tetraloop stability. PMID:20047989

Sheehy, Justin P.; Davis, Amber R.; Znosko, Brent M.

2010-01-01

33

Naturally occurring hepatozoonosis in coyotes from Oklahoma.  

PubMed

Nine of 16 free-ranging coyotes (Canis latrans) from central Oklahoma (USA) had naturally acquired infections of Hepatozoon americanum. Infections were confirmed by recognition of tissue stages closely resembling H. americanum in skeletal and cardiac muscle. At the time coyotes were collected they were infested with a variety of ticks, including adult Gulf Coast ticks (Amblyomma maculatum). We propose that the high prevalence of H. americanum in this small sample of free-ranging coyotes and the ability of these same animals to harbor adult populations of A. maculatum is an important component of the epizootiology of canine hepatozoonosis in North America. PMID:10073352

Kocan, A A; Breshears, M; Cummings, C; Panciera, R J; Ewing, S A; Barker, R W

1999-01-01

34

Naturally occurring antinociceptive substances from plants.  

PubMed

Despite the progress that has occurred in recent years in the development of therapy, there is still a need for effective and potent analgesics, especially for the treatment of chronic pain. One of the most important analgesic drugs employed in clinical practice today continues to be the alkaloid morphine. In this review, emphasis will be given to the important contribution and the history of Papaver somniferum, Salix species, Capsicum species and Cannabis sativa in the development of new analgesics and their importance in the understanding of the complex pathways related to electrophysiological and molecular mechanisms associated with pain transmission. Recently discovered antinociceptive substances include alkaloids, terpenoids and flavonoid. Plant-derived substances have, and will certainly continue to have, a relevant place in the process of drug discovery, particularly in the development of new analgesic drugs. PMID:10960893

Calixto, J B; Beirith, A; Ferreira, J; Santos, A R; Filho, V C; Yunes, R A

2000-09-01

35

Dog models of naturally occurring cancer.  

PubMed

Studies using dogs provide an ideal solution to the gap in animal models for natural disease and translational medicine. This is evidenced by approximately 400 inherited disorders being characterized in domesticated dogs, most of which are relevant to humans. There are several hundred isolated populations of dogs (breeds) and each has a vastly reduced genetic variation compared with humans; this simplifies disease mapping and pharmacogenomics. Dogs age five- to eight-fold faster than do humans, share environments with their owners, are usually kept until old age and receive a high level of health care. Farseeing investigators recognized this potential and, over the past decade, have developed the necessary tools and infrastructure to utilize this powerful model of human disease, including the sequencing of the dog genome in 2005. Here, we review the nascent convergence of genetic and translational canine models of spontaneous disease, focusing on cancer. PMID:21439907

Rowell, Jennie L; McCarthy, Donna O; Alvarez, Carlos E

2011-07-01

36

Dog Models of Naturally Occurring Cancer  

PubMed Central

Studies using dogs provide an ideal solution to the gap in animal models of natural disease and translational medicine. This is evidenced by approximately 400 inherited disorders being characterized in domesticated dogs, most of which are relevant to humans. There are several hundred isolated populations of dogs (breeds) and each has vastly reduced genetic variation compared to humans; this simplifies disease mapping and pharmacogenomics. Dogs age five to eight-fold faster than humans, share environments with their owners, are usually kept until old age, and receive a high level of health care. Farseeing investigators recognized this potential and, over the last decade, developed the necessary tools and infrastructure to utilize this powerful model of human disease, including the sequencing of the dog genome in 2005. Here we review the nascent convergence of genetic and translational canine models of spontaneous disease, focusing on cancer. PMID:21439907

Rowell, Jennie L.; McCarthy, Donna O.; Alvarez, Carlos E.

2011-01-01

37

Absolute configuration of naturally occurring glabridin  

PubMed Central

The title compound {systematic name: 4-[(3R)-8,8-dimethyl-3,4-di­hydro-2H-pyrano[2,3-f]chromen-3-yl]benzene-1,3-diol, commonly named glabridin}, C20H20O4, is a species-specific biomarker from the roots Glycyrrhiza glabra L. (European licorice, Fabaceae). In the present study, this prenylated isoflavan has been purified from an enriched CHCl3 fraction of the extract of the root, using three steps of medium-pressure liquid chromatography (MPLC) by employing HW-40F, Sephadex LH-20 and LiChroCN as adsorbents. Pure glabridin was crystallized from an MeOH–H2O mixture (95:5?v/v) to yield colorless crystals containing one mol­ecule per asymmetric unit (Z? = 1) in the space group P212121. Although the crystal structure has been reported before, the determination of the absolute configuration remained uncertain. Stereochemical analysis, including circular dichroism, NMR data and an X-ray diffraction data set with Bijvoet differences, confirms that glabridin, purified from its natural source, is found only in a C3 R configuration. These results can therefore be used as a reference for the assignment of the configuration and enantio­purity of any isolated or synthetic glabridin sample. PMID:24192160

Simmler, Charlotte; Fronczek, Frank R.; Pauli, Guido F.; Santarsiero, Bernard D.

2013-01-01

38

Stable isotope deltas: tiny, yet robust signatures in nature.  

PubMed

Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg can be written as+15 ?Ur. PMID:22462621

Brand, Willi A; Coplen, Tyler B

2012-09-01

39

Stable Carbon Isotopic Signatures and Fractionations Occurring During Fungal Biosynthesis of Methyl Chloride  

NASA Astrophysics Data System (ADS)

Methyl halides are responsible for approximately 25% of the equivalent chlorine involved in stratospheric ozone depletion, yet quantitative understanding of their atmospheric budgets is still incomplete. The use of an isotopic mass balance to constrain these budgets is currently being investigated. The utility of this approach will depend not only on being able to measure the source signatures and loss kinetic isotope effects contributing to their atmospheric budgets, but also in our ability to assess the variability in these terms. Natural methyl halide sources and sinks due to microbial cycling, combined with their large and variable associated isotopic effects, should have discernable effects on the global atmospheric signature of these gases. Thus, we have begun investigating the isotopic signatures of methyl halides produced by fungi, and the fractionations occurring during their biosynthesis, using controlled laboratory cultures. Measurements of the stable carbon isotopic signatures of growth medium, biomass, respired CO2, CH3Cl, and the carbon mass balance were made over the growth cycle of Inonotus andersonii, a wood-rot fungus previously shown to emit methyl halides. Resulting CH3Cl ? 13C signatures were enriched by approximately 10\\permil as compared to those previously reported for Phellinus pomaceus, another wood-rot species1. Fractionations between substrate and biomass \\{? s-b\\}, as well as biomass and gases \\{? b-g\\}, were nearly constant during exponential and early stationary phase growth. Biomass was depleted by 1\\permil compared to the 13C malt extract medium, and CH3Cl and CO2 were depleted by up to 5\\permil compared to the biomass, implying the bulk of the final CH3Cl signature is determined during CH3Cl synthesis and not during uptake of the carbon substrate. However, the magnitude of these fractionations, and the direction of ? s-b, probably depends on the complexity of the substrate. Additionally, a survey of isotopic signatures of CH3Cl produced by several fungal species on C3 and C4 substrates was begun to quantify likely variability in the natural source signature. 1 Harper, DB., R.M. Kalin, J.T.G. Hamilton, and C. Lamb, Carbon Isotope Ratios for Chloromethane of Biological Origin: Potential Tool in Determining Biological Emissions, Environ. Sci.Technol., 35, 3616-3619, 2001.

Shaw, S. L.; Henn, M. R.; Chapela, I. H.; Conrad, M. E.; Goldstein, A. H.

2003-12-01

40

Uranium isotopes in groundwater occurring at Amazonas State, Brazil.  

PubMed

This paper reports the behavior of the dissolved U-isotopes (238)U and (234)U in groundwater providing from 15 cities in Amazonas State, Brazil. The isotope dilution technique accompanied by alpha spectrometry were utilized for acquiring the U content and (234)U/(238)U activity ratio (AR) data, 0.01-1.4µgL(-1) and 1.0-3.5, respectively. These results suggest that the water is circulating in a reducing environment and leaching strata containing minerals with low uranium concentration. A tendency to increasing ARs values following the groundwater flow direction is identified in Manaus city. The AR also increases according to the SW-NE directions: Uarini?Tefé; Manacapuru?Manaus; Presidente Figueiredo?São Sebastião do Uatumã; and Boa Vista do Ramos?Parintins. Such trends are possibly related to several factors, among them the increasing acid character of the waters. The waters analyzed are used for human consumption and the highest dissolved U content is much lower than the maximum established by the World Health Organization. Therefore, in view of this radiological parameter they can be used for drinking purposes. PMID:25528017

da Silva, Márcio Luiz; Bonotto, Daniel Marcos

2015-03-01

41

Observations of large mass-independent fractionation occurring in MC-ICPMS: implications for determination of accurate isotope amount ratios.  

PubMed

Multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) suffers large bias in isotope amount ratio determinations which has to be properly accounted for. The choice of the proper discrimination model is crucial. Over the last few decades, the exponential mass-bias correction model (Russell's law) has become a standard curriculum in isotope amount ratio measurements. In nature, however, isotopic fractionation that deviates significantly from the exponential model has been known for a long time. Recently, such fractionation was also observed in MC-ICPMS. This phenomenon is termed mass-independent fractionation. In this study, significant departure from the mass-dependent fractionation model is reported for germanium and lead with the most dramatic occurring for germanium-73 and lead-204 isotopes wherein, on average, close to a half percent bias was evidenced from the Russell's law. PMID:22023716

Yang, Lu; Mester, Zoltán; Zhou, Lian; Gao, Shan; Sturgeon, Ralph E; Meija, Juris

2011-12-01

42

Caffeine and related methylxanthines: possible naturally occurring pesticides.  

PubMed

Natural and synthetic methylxanthines inhibit insect feeding and are pesticidal at concentrations known to occur in plants. These effects are due primarily to inhibition of phosphodiesterase activity and to an increase in intracellular cyclic adenosine monophosphate. At lower concentrations, methylxanthines are potent synergists of other pesticides known to activate adenylate cyclase in insects. These data suggest that methylxanthines may function as natural insecticides and that phosphodiesterase inhibitors, alone or in combination with other compounds, may be useful in insect control. PMID:6207592

Nathanson, J A

1984-10-12

43

Naturally occurring arsenic in groundwaters of the midwestern United States  

Microsoft Academic Search

High concentrations of naturally occurring arsenic are present in alluvial groundwater systems in the midwestern United States. These occurrences tend to be sporadic because the arsenic is mobilized only under a narrow range of redox conditions. The reducing conditions must be sufficient to reduce and dissolve iron and manganese but not to produce sulfide. Typically, the affected aquifers are relatively

Nic Korte

1991-01-01

44

Signatures for several types of naturally occurring radioactive materials  

Microsoft Academic Search

Detectors to scan for illicit nuclear material began to be installed at various screening locations in 2002. On the sites considered, each vehicle drives slowly by radiation detectors that scan for neutron and gamma radiation, resulting in a time series profile. One performance limitation is that naturally occurring radioactive materials (NORM), such as cat litter, are routinely shipped across borders,

Tom Burr; Kary Myers

2008-01-01

45

Measuring and Modeling Naturally Occurring Radioactive Material: Interpreting the Relationship Between the Natural Radionuclides Present  

SciTech Connect

The regulatory release of sites and facilities (property) for restricted or unrestricted use has evolved beyond prescribed levels to model-derived dose and risk based limits. Dose models for deriving corresponding soil and structure radionuclide concentration guidelines are necessarily simplified representations of complex processes. A conceptual site model is often developed to present a reasonable and somewhat conservative representation of the physical and chemical properties of the impacted material. Dose modeling software is then used to estimate resulting dose and/or radionuclide specific acceptance criteria (activity concentrations). When the source term includes any or all of the uranium, thorium or actinium natural decay series radionuclides the interpretation of the relationship between the individual radionuclides of the series is critical to a technically correct and complete assessment of risk and/or derivation of radionuclide specific acceptance criteria. Unlike man-made radionuclides, modeling and measuring naturally occurring radioactive material (NORM) and technologically enhanced NORM (TENORM) source terms involves the interpretation of the relationship between the radionuclide present, e.g., secular equilibrium, enrichment, depletion or transient equilibrium. Isotopes of uranium, radium, and thorium occur in all three natural decay series. Each of the three series also produces a radon gas isotope as one of its progeny. In nature, the radionuclides in the three natural decay series are in a state that is approaching or has achieved secular equilibrium, in which the activities of all radionuclides within each series are nearly equal. However, ores containing the three natural decay series may begin in approximate secular equilibrium, but after processing, equilibrium may be broken and certain elements (and the radioactive isotopes of that element) may be concentrated or removed. Where the original ore may have contained one long chain of natural decay series radionuclides, the resulting TENORM source term may contain several smaller decay chains, each headed by a different longer lived member of the original series. This paper presents the anatomy of common TENORM source terms and the pitfalls of measuring, interpreting and modeling these source terms. Modeling TENORM with common software such as RESRAD is discussed. In summary: RESRAD modeling (dose assessments) to derive single radionuclide, dose based acceptance criteria, requires a good understanding of the physical, chemical and biological factors/input parameters applicable to the selected exposure scenario(s). When NORM or TENORM source terms are modeled, an additional understanding of the status of equilibrium, is necessary to accurately perform a dose assessment in support of dose based acceptance criteria. Historical information about the site processes/ores, selection of appropriate analytical analyses to identify key decay series radionuclide and a comprehensive review of the characterization data are needed to understand the equilibrium status of the decay series present. Once the source term has been characterized (in regards to relative activities of the radionuclides within a decay series) the source term must be input into RESRAD to reflect that status of equilibrium at time zero, or at the time since placement, if the characterization data reflects the equilibrium status of dated material. When the RESRAD output file is reviewed, depending on the time of maximum dose, DCGL values may be artificially high in value. Sum of fraction calculations, based on the status of equilibrium of each decay series, can also be used to assess the RESRAD results and develop an appropriate MARSSIM final status survey protocol. (authors)

Lombardo, A.J.; Mucha, A.F. [Safety and Ecology Corporation, 2800 Solway Road, Knoxville, TN (United States)

2008-07-01

46

Naturally occurring tumours in the basal metazoan Hydra.  

PubMed

The molecular nature of tumours is well studied in vertebrates, although their evolutionary origin remains unknown. In particular, there is no evidence for naturally occurring tumours in pre-bilaterian animals, such as sponges and cnidarians. This is somewhat surprising given that recent computational studies have predicted that most metazoans might be prone to develop tumours. Here we provide first evidence for naturally occurring tumours in two species of Hydra. Histological, cellular and molecular data reveal that these tumours are transplantable and might originate by differentiation arrest of female gametes. Growth of tumour cells is independent from the cellular environment. Tumour-bearing polyps have significantly reduced fitness. In addition, Hydra tumours show a greatly altered transcriptome that mimics expression shifts in vertebrate cancers. Therefore, this study shows that spontaneous tumours have deep evolutionary roots and that early branching animals may be informative in revealing the fundamental mechanisms of tumorigenesis. PMID:24957317

Domazet-Lošo, Tomislav; Klimovich, Alexander; Anokhin, Boris; Anton-Erxleben, Friederike; Hamm, Mailin J; Lange, Christina; Bosch, Thomas C G

2014-01-01

47

Arsenic poisoning in dairy cattle from naturally occurring arsenic pyrites.  

PubMed

An outbreak of arsenic poisoning occurred in which most of a 200 cow dairy herd were affected and six died. The source of the arsenic was naturally occurring arsenic pyrites from the Waiotapu Stream, near Rotorua. Arsenic levels in the nearby soil were as high as 6618 ppm. There was little evidence to suggest that treatment affected the course of the disease. Haematology was of little use in diagnosis, post-mortem signs were not always consistent and persistence of the element in the liver appeared short. Control of further outbreaks have been based on practical measures to minimise the intake of contaminated soil and free laying water by the stock. PMID:16031332

Hopkirk, R G

1987-10-01

48

An Update on Antitumor Activity of Naturally Occurring Chalcones  

PubMed Central

Chalcones, which have characteristic 1,3-diaryl-2-propen-1-one skeleton, are mainly produced in roots, rhizomes, heartwood, leaves, and seeds of genera Angelica, Sophora, Glycyrrhiza, Humulus, Scutellaria, Parartocarpus, Ficus, Dorstenia, Morus, Artocarpus, and so forth. They have become of interest in the research and development of natural antitumor agents over the past decades due to their broad range of mechanisms including anti-initiation, induction of apoptosis, antiproliferation, antimetastasis, antiangiogenesis, and so forth. This review summarizes the studies on the antitumor activity of naturally occurring chalcones and their underlying mechanisms in detail during the past decades. PMID:23690855

Zhang, En-Hui; Wang, Ru-Feng; Guo, Shu-Zhen; Liu, Bin

2013-01-01

49

Naturally occurring crystalline phases: analogues for radioactive waste forms  

SciTech Connect

Naturally occurring mineral analogues to crystalline phases that are constituents of crystalline radioactive waste forms provide a basis for comparison by which the long-term stability of these phases may be estimated. The crystal structures and the crystal chemistry of the following natural analogues are presented: baddeleyite, hematite, nepheline; pollucite, scheelite;sodalite, spinel, apatite, monazite, uraninite, hollandite-priderite, perovskite, and zirconolite. For each phase in geochemistry, occurrence, alteration and radiation effects are described. A selected bibliography for each phase is included.

Haaker, R.F.; Ewing, R.C.

1981-01-01

50

An update on antitumor activity of naturally occurring chalcones.  

PubMed

Chalcones, which have characteristic 1,3-diaryl-2-propen-1-one skeleton, are mainly produced in roots, rhizomes, heartwood, leaves, and seeds of genera Angelica, Sophora, Glycyrrhiza, Humulus, Scutellaria, Parartocarpus, Ficus, Dorstenia, Morus, Artocarpus, and so forth. They have become of interest in the research and development of natural antitumor agents over the past decades due to their broad range of mechanisms including anti-initiation, induction of apoptosis, antiproliferation, antimetastasis, antiangiogenesis, and so forth. This review summarizes the studies on the antitumor activity of naturally occurring chalcones and their underlying mechanisms in detail during the past decades. PMID:23690855

Zhang, En-Hui; Wang, Ru-Feng; Guo, Shu-Zhen; Liu, Bin

2013-01-01

51

Synthetic muscle promoters: activities exceeding naturally occurring regulatory sequences  

NASA Technical Reports Server (NTRS)

Relatively low levels of expression from naturally occurring promoters have limited the use of muscle as a gene therapy target. Myogenic restricted gene promoters display complex organization usually involving combinations of several myogenic regulatory elements. By random assembly of E-box, MEF-2, TEF-1, and SRE sites into synthetic promoter recombinant libraries, and screening of hundreds of individual clones for transcriptional activity in vitro and in vivo, several artificial promoters were isolated whose transcriptional potencies greatly exceed those of natural myogenic and viral gene promoters.

Li, X.; Eastman, E. M.; Schwartz, R. J.; Draghia-Akli, R.

1999-01-01

52

Crystal structure of naturally occurring mercury(II) amidonitrate  

NASA Astrophysics Data System (ADS)

A naturally-occurring mercuroammonium compound from Pitkin County, Colorado, is shown to be the natural analog of synthetic HgNH 2NO 3. The crystals are isometric, P4 132 or P4 332, with a = 10.254(1)Å and twelve formula weights per cell. Using 437 symmetry-independent reflections, the crystal structure was partially determined and refined to a residual of 0.090. The positions of the Hg atoms and the N and O atoms of the nitrate group were determined, but the amide ion could not be located, probably due to positional disorder. The structure contains mercury atoms arranged in equilateral triangles 3.421(1) Å on a side. These triangles are linked through shared vertices into helical chains wound around the fourfold screw axes. Similar triangular units occur in other inorganic Hg(II) compounds. The distortion of the nitrate ion from trigonal planar symmetry is also discussed.

Randall, Charles J.; Peacor, Donald R.; Rouse, Roland C.; Dunn, Pete J.

1982-05-01

53

Diversified bioactivities of four types of naturally occurring quinochalcones.  

PubMed

Quinochalcones, quinone-containing chalcones, belong to the flavonoid family and have attracted increasing popularity in Western countries in the last decade due to their pharmacological activities. This review describes four types of naturally occurring quinochalcones and summarizes their different pharmacological activities, including anti-cerebral ischemia, anti-tumor, and anti-infection activities. In addition, the pharmacological activities and relevant structure-activity relationships of synthetic quinochalcones are also reviewed. PMID:25172102

Zhao, Siyu; Lu, Xinmiao; Xiao, Cheng; Ning, Zhangchi; Zeng, Honglian; Ding, Xinzhe; Zhang, Yinhuan; Lu, Cheng; Liu, Yuanyan

2014-12-01

54

Naturally occurring benzodiazepines: current status of research and clinical implications  

Microsoft Academic Search

Naturally occurring benzodiazepines (BZDs) were first detected in mammalian tissues in 1986. They comprise a variety of 1,4-benzodiazepines\\u000a corresponding to drugs commercially available for the treatment of anxiety disorders, sleep disturbances and epileptic seizures.\\u000a Several biosynthetic pathways leading to the formation of BZDs are currently being discussed and have led to the proposition\\u000a of possible precursor molecules.\\u000a \\u000a For years, the

Philipp Sand; Dominique Kavvadias; Doris Feineis; Peter Riederer; Peter Schreier; Matthias Kleinschnitz; Franz-Christian Czygan; Ahmed Abou-Mandour; Gerhard Bringmann; Helmut Beckmann

2000-01-01

55

Naturally Occurring Incidents as Facsimiles for Biochemical Terrorist Attacks  

Microsoft Academic Search

\\u000a Research on techniques for effective bioterrorism surveillance is limited by the availability of data from actual bioterrorism\\u000a incidents. This research explores the potential contribution of naturally occurring incidents, such as Florida wildfires,\\u000a as reasonable facsimiles for airborne bioterrorist attacks. Hospital discharge data on respiratory illnesses are analyzed\\u000a to uncover patterns that might resemble the effects of an aerosolized biological or

Jamie L. Griffiths; Donald J. Berndt; Alan R. Hevner

2006-01-01

56

Naturally Occurring Anthraquinones: Chemistry and Therapeutic Potential in Autoimmune Diabetes  

PubMed Central

Anthraquinones are a class of aromatic compounds with a 9,10-dioxoanthracene core. So far, 79 naturally occurring anthraquinones have been identified which include emodin, physcion, cascarin, catenarin, and rhein. A large body of literature has demonstrated that the naturally occurring anthraquinones possess a broad spectrum of bioactivities, such as cathartic, anticancer, anti-inflammatory, antimicrobial, diuretic, vasorelaxing, and phytoestrogen activities, suggesting their possible clinical application in many diseases. Despite the advances that have been made in understanding the chemistry and biology of the anthraquinones in recent years, research into their mechanisms of action and therapeutic potential in autoimmune disorders is still at an early stage. In this paper, we briefly introduce the etiology of autoimmune diabetes, an autoimmune disorder that affects as many as 10 million worldwide, and the role of chemotaxis in autoimmune diabetes. We then outline the chemical structure and biological properties of the naturally occurring anthraquinones and their derivatives with an emphasis on recent findings about their immune regulation. We discuss the structure and activity relationship, mode of action, and therapeutic potential of the anthraquinones in autoimmune diabetes, including a new strategy for the use of the anthraquinones in autoimmune diabetes.

Wu, Yueh-Chen

2015-01-01

57

Naturally occurring anti-tissue antibodies in rat sera  

PubMed Central

Seventy per cent of normal rat sera have been shown to contain heat labile serum component(s) active against various rat organ homogenates as demonstrated by haemolytic complement fixation and passive haemagglutination tests. The main antigenic activity in rat liver has been found in the mitochondrial fractions. It was also demonstrated by the indirect fluorescent antibody technique that both guinea-pig complement and high molecular weight rat globulins were fixed to rat organ sections. Chemotactic activity has also been observed with rat serum and rat liver mitochondria and it is suggested that these naturally occurring antibodies may be implicated in the removal of tissue breakdown products. PMID:5338951

Weir, D. M.; Pinckard, R. N.; Elson, C. J.; Suckling, Deirdre E.

1966-01-01

58

The sensitizing capacity of chimaphilin, a naturally-occurring quinone.  

PubMed

Chimaphilin is a yellow naphthoquinone which occurs naturally in various chimaphila and Pyrola species. In Chimaphila umbellata (winter green) and C. maculata, it is a major constituent. Folk medicine recommends the leaves of Chimaphila species as a topical application to treat skin diseases. Since 1887, winter green is claimed to have caused dermatitis and to have been responsible for "idiosyncrasy". Experimental sensitization using the open epicutaneous as well as Freund's complete adjuvant technique has now revealed that chimaphilin is a moderate contact sensitizer. PMID:3191678

Hausen, B M; Schiedermair, I

1988-09-01

59

Naturally occurring low-dose lithium in drinking water.  

PubMed

Recently, a series of ecological studies on antisuicidal properties of naturally occurring lithium contents in drinking water have sparked interest among researchers. In this issue, Ishii and colleagues present further argument for the hypothesis that even low lithium doses-or rather, doses of lithium at a supplemental level-might have their place in suicide prevention.With limitations, there is some evidence from randomized controlled trials (RCTs) supporting lithium in therapeutic doses as a suicide preventative in individuals with unipolar depression, bipolar disorder, schizoaffective disorder, dysthymia, or rapid cycling. PMID:25830462

Kapusta, Nestor D; König, Daniel

2015-03-01

60

Naturally occurring radionuclides in agricultural products: An overview  

SciTech Connect

Low levels of naturally occurring radionuclides exist in phosphatic clays, a by-product of phosphatic mining and beneficiation processes. Concerns about these radionuclides entering the human food chain were an immediate research priority before the phosphate clays could be reclaimed for intensive agricultural purposes. Efforts included the assembly of a large body of data from both sons and plants, part of which were produced by the Polk County (Florida) Mined Lands Agricultural Research/Demonstration Project MLAR/DP. Additional detailed studies involving dairy and beef cattle (Bos taurus) were conducted by researchers working with the MLAR/DP. A national symposium was conducted in which data concerning the MLAR/DP work and other research projects also dealing with naturally occurring radionuclides in agriculture could be discussed. The symposium included invited review papers dealing with the identification of radionuclide geological origins, the geochemistry and movement of radionuclides within the environment, mechanisms of plant uptake, entry points into the food chain, and evaluation of dose and risk assessment to the consumer of low levels of radionuclides. The risk to human health of an individual obtaining 0.1 of his or her dietary intake from crops produced on phosphatic clays increased by 1 in 5 x 10{sup 6}/yr above a control individual consuming no food grown on phosphatic clays. Leaf tissues were found to be generally higher than fruit, grain, or root tissues. The natural range in radionuclide content among various food types was greater than the difference in radionuclides content between the same food produced on phosphatic clays vs. natural soils. 19 refs.

Hanlon, E.A. [Univ. of Florida, Gainesville, FL (United States)

1994-07-01

61

Helium isotopic abundance variation in nature  

SciTech Connect

The isotopic abundance of helium in nature has been reviewed. This atomic weight value is based on the value of helium in the atmosphere, which is invariant around the world and up to a distance of 100,000 feet. Helium does vary in natural gas, volcanic rocks and gases, ocean floor sediments, waters of various types and in radioactive minerals and ores due to {alpha} particle decay of radioactive nuclides.

Holden, N.E.

1993-08-01

62

Macaques exhibit a naturally-occurring depression similar to humans.  

PubMed

Rodent models have dominated preclinical investigations into the mechanisms of depression. However, these models-which rely on subjecting individual rodents to physical stressors - do not realistically resemble the etiopathological development of depression, which occurs naturally in a social context. A non-human primate model that better reflects the social ethological aspects of depression would be more advantageous to investigating pathophysiological mechanisms and developing antidepressant therapeutics. Here, we describe and model a naturally-occurring depressive state in a non-human primate species, the cynomolgus monkey (Macaca fascicularis), in a realistic social ethological context and associate the depressed behavioral phenotype with significant serum metabolic perturbations. One to two subjects per stable social colony (17-22 subjects) manifested a depressive phenotype that may be attributed to psychosocial stress. In accordance with rodent and human studies, the serum metabolic phenotype of depressed and healthy subjects significantly differed, supporting the model's face validity. However, application of the fast-acting antidepressant ketamine failed to demonstrate predictive validity. This study proposes a non-human primate depression model in a realistic social ethological context that can better approximate the psychosocial stressors underlying depression. PMID:25783476

Xu, Fan; Wu, Qingyuan; Xie, Liang; Gong, Wei; Zhang, Jianguo; Zheng, Peng; Zhou, Qinmin; Ji, Yongjia; Wang, Tao; Li, Xin; Fang, Liang; Li, Qi; Yang, Deyu; Li, Juan; Melgiri, Narayan D; Shively, Carol; Xie, Peng

2015-01-01

63

Macaques Exhibit a Naturally-Occurring Depression Similar to Humans  

PubMed Central

Rodent models have dominated preclinical investigations into the mechanisms of depression. However, these models-which rely on subjecting individual rodents to physical stressors - do not realistically resemble the etiopathological development of depression, which occurs naturally in a social context. A non-human primate model that better reflects the social ethological aspects of depression would be more advantageous to investigating pathophysiological mechanisms and developing antidepressant therapeutics. Here, we describe and model a naturally-occurring depressive state in a non-human primate species, the cynomolgus monkey (Macaca fascicularis), in a realistic social ethological context and associate the depressed behavioral phenotype with significant serum metabolic perturbations. One to two subjects per stable social colony (17–22 subjects) manifested a depressive phenotype that may be attributed to psychosocial stress. In accordance with rodent and human studies, the serum metabolic phenotype of depressed and healthy subjects significantly differed, supporting the model's face validity. However, application of the fast-acting antidepressant ketamine failed to demonstrate predictive validity. This study proposes a non-human primate depression model in a realistic social ethological context that can better approximate the psychosocial stressors underlying depression. PMID:25783476

Xu, Fan; Wu, Qingyuan; Xie, Liang; Gong, Wei; Zhang, Jianguo; Zheng, Peng; Zhou, Qinmin; Ji, Yongjia; Wang, Tao; Li, Xin; Fang, Liang; Li, Qi; Yang, Deyu; Li, Juan; Melgiri, Narayan D.; Shively, Carol; Xie, Peng

2015-01-01

64

Regulation of naturally occurring radioactive materials in Australia.  

PubMed

In order to promote uniformity between jurisdictions, the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has developed the National Directory for Radiation Protection, which is a regulatory framework that all Australian governments have agreed to adopt. There is a large and diverse range of industries involved in mining or mineral processing, and the production of fossil fuels in Australia. Enhanced levels of naturally occurring radionuclides can be associated with mineral extraction and processing, other industries (e.g. metal recycling) and some products (e.g. plasterboard). ARPANSA, in conjunction with industry and State regulators, has undertaken a review and assessment of naturally occurring radioactive material (NORM) management in Australian industries. This review has resulted in guidance on the management of NORM that will be included in the National Directory for Radiation Protection. The first NORM safety guide provides the framework for NORM management and addresses specific NORM issues in oil and gas production, bauxite, aluminium and phosphate industries. Over time further guidance material for other NORM-related industries will be developed. This presentation will provide an overview of the regulatory approach to managing NORM industries in Australia. PMID:21515621

Jeffries, Cameron; Akber, Riaz; Johnston, Andrew; Cassels, Brad

2011-07-01

65

Naturally Occurring Animal Models of Human Hepatitis E Virus Infection  

PubMed Central

Hepatitis E virus (HEV) is a single-stranded, positive-sense RNA virus in the family Hepeviridae. Hepatitis E caused by HEV is a clinically important global disease. There are currently four well-characterized genotypes of HEV in mammalian species, although numerous novel strains of HEV likely belonging to either new genotypes or species have recently been identified from several other animal species. HEV genotypes 1 and 2 are limited to infection in humans, whereas genotypes 3 and 4 infect an expanding host range of animal species and are zoonotic to humans. Historical animal models include various species of nonhuman primates, which have been indispensable for the discovery of human HEV and for understanding its pathogenesis and course of infection. With the genetic identification and characterization of animal strains of HEV, a number of naturally occurring animal models such as swine, chicken, and rabbit have recently been developed for various aspects of HEV research, including vaccine trials, pathogenicity, cross-species infection, mechanism of virus replication, and molecular biology studies. Unfortunately, the current available animal models for HEV are still inadequate for certain aspects of HEV research. For instance, an animal model is still lacking to study the underlying mechanism of severe and fulminant hepatitis E during pregnancy. Also, an animal model that can mimic chronic HEV infection is critically needed to study the mechanism leading to chronicity in immunocompromised individuals. Genetic identification of additional novel animal strains of HEV may lead to the development of better naturally occurring animal models for HEV. This article reviews the current understanding of animal models of HEV infection in both natural and experimental infection settings and identifies key research needs and limitations. PMID:24936039

Yugo, Danielle M.; Cossaboom, Caitlin M.; Meng, Xiang-Jin

2014-01-01

66

Natural and artificial alpha radioactivity of platinum isotopes  

Microsoft Academic Search

The partial alpha emission half-life for the naturally occurring and artificially produced platinum isotopes (Z=78) was evaluated in the framework of a semiempirical, one-parameter model based on the quantum mechanical tunneling mechanism through a Coulomb-plus-centrifugal-plus-overlapping potential barrier within the spherical nucleus approximation. This approach has been shown to be exceptionally well suited (to a level of 90% of the cases

O. A. P. Tavares; E. L. Medeiros

2011-01-01

67

Each summer, fish kills occur in freshwater and saltwater environments. They occur in natural  

E-print Network

. This process, known as photosynthesis occurs during daylight hours. Photosynthesis is conducted by submerged. Oxygen enters water from the atmosphere and through photosynthesis by aquatic plants and algae. Diffusion photosynthesis occurs only during daylight hours and respiration (or use of oxygen) occurs day and night

Jawitz, James W.

68

Discrimination of Naturally Occurring Radioactive Material in Plastic Scintillator Material  

SciTech Connect

Plastic scintillator material is used in many applications for the detection of gamma-rays from radioactive material, primarily due to the sensitivity per unit cost compared to other detection materials. However, the resolution and lack of full-energy peaks in the plastic scintillator material prohibits detailed spectroscopy. Therefore, other materials such as doped sodium iodide are used for spectroscopic applications. The limited spectroscopic information can however be exploited in plastic scintillator materials to provide some discrimination. The discrimination between man-made and naturally occurring sources would be useful in reducing alarm screening for radiation detection applications which target man-made sources. The results of applying the limited energy information from plastic scintillator material for radiation portal monitors are discussed.

Ely, James H.; Kouzes, Richard T.; Geelhood, Bruce D.; Schweppe, John E.; Warner, Ray A.

2003-08-19

69

Naturally occurring mercury contamination in a pristine environment?  

NASA Astrophysics Data System (ADS)

About 19 percent of sampled residential water wells situated in a pristine, granitic Maine (USA) coastal environment have elevated mercury concentrations according to USEPA standards. There are no identified anthropogenic sources for mercury but some local granitoids have anomalous mercury concentrations in the Waldoboro Pluton Complex (WPC). Site-specific hydrogeologic conditions appear to have aggravated what is otherwise only trace amounts of some naturally occurring toxic analytes in the groundwater in contact with the suspect granitoids of the WPC. The extent of mercury in this crystalline rock environment is examined here. It is prudent to exercise preventive measures and appropriately site water supply wells and not expect complete remediation of the affected homeowners' wells.

Sidle, W. C.

1993-04-01

70

Signatures for several types of naturally occurring radioactive materials.  

PubMed

Detectors to scan for illicit nuclear material began to be installed at various screening locations in 2002. On the sites considered, each vehicle drives slowly by radiation detectors that scan for neutron and gamma radiation, resulting in a time series profile. One performance limitation is that naturally occurring radioactive materials (NORM), such as cat litter, are routinely shipped across borders, leading to nuisance alarms. One strategy for nuisance alarms is to define and recognize "signatures" of certain types of NORM so that many nuisance alarms can be quickly resolved as being innocent. Here, we consider candidate profile features, such as the peak width and the maximum energy ratio, and use pattern recognition methods to illustrate the extent to which several common types of NORM can be distinguished. PMID:18378153

Burr, Tom; Myers, Kary

2008-09-01

71

Fenugreek: a naturally occurring edible spice as an anticancer agent  

PubMed Central

In recent years, various dietary components that can potentially be used for the prevention and treatment of cancer have been identified. In this study, we demonstrate that extract (FE) from the seeds of the plant Trigonella foenum graecum, commonly called fenugreek, are cytotoxic in vitro to a panel of cancer but not normal cells. Treatment with 10-15 ug/mL of FE for 72h was growth inhibitory to breast, pancreatic and prostate cancer cell lines (PCa). When tested at higher doses (15-20 ug/mL), FE continued to be growth inhibitory to PCa cell lines but not to either primary prostate or htert-immortalized prostate cells. At least part of the growth inhibition is due to induction of cell death, as seen by incorporation of Ethidium Bromide III into cancer cells exposed to FE. Molecular changes induced in PCa cells are: in DU-145 cells: down regulation of mutant p53, and in PC-3 cells up regulation of p21 and inhibition of TGF-? induced phosphorylation of Akt. The surprising finding of our studies is that death of cancer cells occurs despite growth stimulatory pathways being simultaneously up regulated (phosphorylated) by FE. Thus, these studies add another biologically active agent to our armamentarium of naturally occurring agents with therapeutic potential. PMID:19197146

Shabbeer, Shabana; Sobolewski, Michelle; Kachhap, Sushant; Davidson, Nancy; Carducci, Michael A.; Khan, Saeed

2011-01-01

72

Explanation for naturally occurring supernumerary limbs in amphibians.  

PubMed

The occasional occurrence of high frequencies of limb abnormalities, including extra limbs, in natural populations of amphibians has long been a puzzle. In this paper we report the discovery of a population in which such limb abnormalities appear to be caused by a parasitic flatworm (trematode) that uses amphibians as intermediate hosts. The cercarial larval stage of the trematode attacks amphibians, penetrating the skin to form cysts (metacercariae). The cysts are preferentially localized in the cloacal region, including the developing hind limb regions in larvae of both frogs (Hyla regilla) and salamanders (Ambystoma macrodactylum). A wide range of limb abnormalities are seen, including duplicated limb structures ranging from extra digits to several extra whole limbs. We hypothesize that these limb abnormalities result from localized regulatory responses of developing and regenerating limb tissues to mechanical disruption caused by the trematode cysts. We have tested this idea by implanting inert resin beads into developing limb buds of frogs and salamanders. Since this treatment can cause supernumerary limb structures, our hypothesis is sufficient to explain the naturally occurring extra limbs. PMID:2348164

Sessions, S K; Ruth, S B

1990-04-01

73

Laboratory observation of naturally occurring dust-density waves  

NASA Astrophysics Data System (ADS)

Dust-density waves are electrostatic compressional waves that propagate in dusty plasma. Compared to the more familiar ion-acoustic waves, in dust-density waves, inertia is provided by dust particles (instead of ions) while pressure is provided by the ions as well as electrons (not just electrons). In a laboratory experiment, we observed dust density waves in a 3D void-free dusty plasma. The waves occur naturally due to an ion-flow instability. Dust particles (4.8 microns) are levitated within the volume of a glass box that rests atop an electrode in a radio-frequency glow discharge plasma. Horizontal confinement of dust particles is provided by the plasma's natural electric field that is enhanced by the walls of the glass box, while vertical confinement is due to the electrode's sheath. We observed dust-density waves with planar wave fronts propagating in alignment with flowing ions. By directly imaging the dust particles with a 500 frame-per-second camera, we monitor the dust density modulations in both space and time. A typical wave propagates at 40 mm/s with a frequency of 24 Hz. In this work, we characterize these waves and their growth as they propagate.

Flanagan, Tim; Goree, John

2010-11-01

74

A nitrogen and sulfur isotope investigation of redox conditions occurring in a shallow outwash aquifer.  

NASA Astrophysics Data System (ADS)

The sources and distribution of elevated nitrate and sulfate concentrations were determined using nitrogen and sulfur isotopes in groundwater from an unconfined outwash aquifer located in Jackson County, southern Indiana. Land use is mostly agricultural. Local farmers apply nitrogeneous inorganic fertilizers to their fields. In addition, two commercial confined feedlots house over two million chickens, and wastes are stored in seven interconnected lagoons at the larger feedlot. These wastes are later applied to an adjacent field via spray irrigation. Over 50 shallow wells (5 m deep), domestic wells (7 m deep) and deep wells (15to 20 m deep) were sampled over a two- year period to monitor nitrogen and sulfur inputs from these sources. Most shallow groundwater in the study area is above the EPA drinking water standards for nitrate-N (>10 mgL). Nitrate concentrations are highest down gradient from the spray irrigation field (53.5 mgL), yet are also elevated in up gradient groundwaters. Nitrogen isotopes are enriched in the heavier isotope (d15N-NO3 > +13.7 ooo) down gradient from the large feedlot and lightest signatures (d15N-NO3 < +2.0 ooo) are found in up gradient groundwater underlying fields that use inorganic fertilizers. Analytes associated with feedlot wastes (sodium, potassium, chloride and sulfate) are also elevated down gradient from the larger feedlot. Deep groundwater has no nitrate and higher sulfate concentrations than shallow waters. In two sets of multi-level wells, enrichment in both oxygen and nitrogen isotopes indicates that denitrification may occur at two depths: 1) locally in shallow waters adjacent to the waste lagoons; and 2) in deeper waters (approximately 10 m) throughout the study area. Sulfate isotopic signatures in deep groundwater approach the signature of pyrite found within the outwash (d34S-SO4 = -11.6 ooo). Autotrophic denitrification may be occurring where nitrate is reduced and the oxidation of pyrite is adding sulfate with depth.

Spalding, R.; Hartke, E.

2001-12-01

75

Forecasting Seizures in Dogs with Naturally Occurring Epilepsy  

PubMed Central

Seizure forecasting has the potential to create new therapeutic strategies for epilepsy, such as providing patient warnings and delivering preemptive therapy. Progress on seizure forecasting, however, has been hindered by lack of sufficient data to rigorously evaluate the hypothesis that seizures are preceded by physiological changes, and are not simply random events. We investigated seizure forecasting in three dogs with naturally occurring focal epilepsy implanted with a device recording continuous intracranial EEG (iEEG). The iEEG spectral power in six frequency bands: delta (0.1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (12–30 Hz), low-gamma (30–70 Hz), and high-gamma (70–180 Hz), were used as features. Logistic regression classifiers were trained to discriminate labeled pre-ictal and inter-ictal data segments using combinations of the band spectral power features. Performance was assessed on separate test data sets via 10-fold cross-validation. A total of 125 spontaneous seizures were detected in continuous iEEG recordings spanning 6.5 to 15 months from 3 dogs. When considering all seizures, the seizure forecasting algorithm performed significantly better than a Poisson-model chance predictor constrained to have the same time in warning for all 3 dogs over a range of total warning times. Seizure clusters were observed in all 3 dogs, and when the effect of seizure clusters was decreased by considering the subset of seizures separated by at least 4 hours, the forecasting performance remained better than chance for a subset of algorithm parameters. These results demonstrate that seizures in canine epilepsy are not randomly occurring events, and highlight the feasibility of long-term seizure forecasting using iEEG monitoring. PMID:24416133

Stead, S. Matt; Brinkmann, Ben; Vasoli, Vincent; Crepeau, Daniel; Vite, Charles H.; Sturges, Beverly; Ruedebusch, Vanessa; Mavoori, Jaideep; Leyde, Kent; Sheffield, W. Douglas; Litt, Brian; Worrell, Gregory A.

2014-01-01

76

Global distribution of naturally occurring marine hypoxia on continental margins  

NASA Astrophysics Data System (ADS)

Hypoxia in the ocean influences biogeochemical cycling of elements, the distribution of marine species and the economic well being of many coastal countries. Previous delineations of hypoxic environments focus on those in enclosed seas where hypoxia may be exacerbated by anthropogenically induced eutrophication. Permanently hypoxic water masses in the open ocean, referred to as oxygen minimum zones, impinge on a much larger seafloor surface area along continental margins of the eastern Pacific, Indian and western Atlantic Oceans. We provide the first global quantification of naturally hypoxic continental margin floor by determining upper and lower oxygen minimum zone depth boundaries from hydrographic data and computing the area between the isobaths using seafloor topography. This approach reveals that there are over one million km 2 of permanently hypoxic shelf and bathyal sea floor, where dissolved oxygen is <0.5 ml l -1; over half (59%) occurs in the northern Indian Ocean. We also document strong variation in the intensity, vertical position and thickness of the OMZ as a function of latitude in the eastern Pacific Ocean and as a function of longitude in the northern Indian Ocean. Seafloor OMZs are regions of low biodiversity and are inhospitable to most commercially valuable marine resources, but support a fascinating array of protozoan and metazoan adaptations to hypoxic conditions.

Helly, John J.; Levin, Lisa A.

2004-09-01

77

Solution of naturally-occurring glasses in the geological environment  

SciTech Connect

As part of a study to investigate the feasibility of putting nuclear wastes in glass containers and burying them on land or dumping them in the ocean, we have made a study of the amount of solution experienced by naturally occurring glasses from two land sites and thirty-four deep-sea sites. The glasses used in this study are microtektites from three strewn fields (Australasian, Ivory Coast, and North American) and from the Zhamanshin impact crater in southern Siberia. The microtektites range in age from 0.7 to 35 m.y. and they have a wide range in composition. Although several criteria for determining the amount of solution were considered, most of the conclusions are based on two criteria: (1) width of cracks, and (2) elevation of silica-rich inclusions above the adjacent microtektite surface. The amount of solution was determined for about 170 microtektites; and measured amounts of solution range from 0.2 to at least 28 {mu}m, but most are less than 5 {mu}m. There appears to be no systematic relationship between age and amount of solution. 21 refs., 7 tabs.

Glass, B.P.

1982-12-01

78

Natural mercury isotope variation in coal deposits and organic soils  

SciTech Connect

There is a need to distinguish among sources of Hg to the atmosphere in order to more fully understand global Hg pollution. In this study we investigate whether coal deposits within the United States, China, and Russia-Kazakhstan, which are three of the five greatest coal-producing regions, have diagnostic Hg isotopic fingerprints that can be used to discriminate among Hg sources. We also investigate the Hg isotopic composition of modern organic soil horizons developed in areas distant from point sources of Hg in North America. Mercury stored in coal deposits displays a wide range of both mass dependent fractionation and mass independent fractionation. {delta}{sup 202}Hg varies in coals by 3{per_thousand} and {Delta}{sup 201}Hg varies by 0.9{per_thousand}. Combining these two Hg isotope signals results in what may be a unique isotopic 'fingerprint' for many coal deposits. Mass independent fractionation of mercury has been demonstrated to occur during photochemical reactions of mercury. This suggests that Hg found in most coal deposits was subjected to photochemical reduction near the Earth's surface prior to deposition. The similarity in MDF and MIF of modern organic soils and coals from North America suggests that Hg deposition from coal may have imprinted an isotopic signature on soils. This research offers a new tool for characterizing mercury inputs from natural and anthropogenic sources to the atmosphere and provides new insights into the geochemistry of mercury in coal and soils. 35 refs., 2 figs., 1 tab.

Abir, Biswas; Joel D. Blum; Bridget A. Bergquist; Gerald J. Keeler; Zhouqing Xie [University of Michigan, Ann Arbor, MI (United States). Department of Geological Sciences

2008-11-15

79

Role of naturally occurring gas hydrates in sediment transport  

SciTech Connect

Naturally occurring gas hydrates have the potential to store enormous volumes of both gas and water in semi-solid form in ocean-bottom sediments and then to release that gas and water when the hydrate's equilibrium condition are disturbed. Therefore, hydrates provide a potential mechanism for transporting large volumes of sediments. Under the combined low bottom-water temperatures and moderate hydrostatic pressures that exist over most of the continental slopes and all of the continental rises and abyssal plains, hydrocarbon gases at or near saturation in the interstitial waters of the near-bottom sediments will form hydrates. The gas can either be autochthonous, microbially produced gas, or allochthonous, catagenic gas from deeper sediments. Equilibrium conditions that stabilize hydrated sediments may be disturbed, for example, by continued sedimentation or by lowering of sea level. In either case, some of the solid gas-water matrix decomposes. Released gas and water volume exceeds the volume occupied by the hydrate, so the internal pressure rises - drastically if large volumes of hydrate are decomposed. Part of the once rigid sediment is converted to a gas- and water-rich, relatively low density mud. When the internal pressure, due to the presence of the compressed gas or to buoyancy, is sufficiently high, the overlying sediment may be lifted and/or breached, and the less dense, gas-cut mud may break through. Such hydrate-related phenomena can cause mud diapirs, mud volcanos, mud slides, or turbidite flows, depending on sediment configuration and bottom topography. 4 figures.

McIver, R.D.

1982-06-01

80

Methamphetamine-induced neurotoxicity disrupts naturally occurring phasic dopamine signaling.  

PubMed

Methamphetamine (METH) is a highly addictive drug that is also neurotoxic to central dopamine (DA) systems. Although striatal DA depletions induced by METH are associated with behavioral and cognitive impairments, the link between these phenomena remains poorly understood. Previous work in both METH-pretreated animals and the 6-hydroxydopamine model of Parkinson's disease suggests that a disruption of phasic DA signaling, which is important for learning and goal-directed behavior, may be such a link. However, previous studies used electrical stimulation to elicit phasic-like DA responses and were also performed under anesthesia, which alters DA neuron activity and presynaptic function. Here we investigated the consequences of METH-induced DA terminal loss on both electrically evoked phasic-like DA signals and so-called 'spontaneous' phasic DA transients measured by voltammetry in awake rats. Not ostensibly attributable to discrete stimuli, these subsecond DA changes may play a role in enhancing reward-cue associations. METH pretreatment reduced tissue DA content in the dorsomedial striatum and nucleus accumbens by ~55%. Analysis of phasic-like DA responses elicited by reinforcing stimulation revealed that METH pretreatment decreased their amplitude and underlying mechanisms for release and uptake to a similar degree as DA content in both striatal subregions. Most importantly, characteristics of DA transients were altered by METH-induced DA terminal loss, with amplitude and frequency decreased and duration increased. These results demonstrate for the first time that denervation of DA neurons alters naturally occurring DA transients and are consistent with diminished phasic DA signaling as a plausible mechanism linking METH-induced striatal DA depletions and cognitive deficits. PMID:23574406

Howard, Christopher D; Daberkow, David P; Ramsson, Eric S; Keefe, Kristen A; Garris, Paul A

2013-07-01

81

Naturally occurring asbestos: a recurring public policy challenge.  

PubMed

The potential environmental hazards and associated public health issues related to exposure to respirable dusts from the vicinity of natural in-place asbestos deposits (commonly referred to as naturally occurring asbestos, NOA) have gained the regulatory and media spotlight in many areas around the United States, such as Libby, MT, Fairfax County, VA, and El Dorado Hills, CA, among others. NOA deposits may be present in a variety of geologic formations. It has been suggested that airborne asbestos may be released from NOA deposits, and absent appropriate engineering controls, may pose a potential health hazard if these rocks are crushed or exposed to natural weathering and erosion or to human activities that create dust. The issue that needs to be addressed at a policy level is the method of assessing exposures to elongated rock fragments ubiquitous in dust clouds in these same environments and the associated risk. Elongated rock fragments and single crystal minerals present in NOA have been construed by some as having attributes, including the health effects, of asbestos fibers. However, the Occupational Safety and Health Administration (OSHA), Mine Safety and Health Administration (MSHA), and the Consumer Products Safety Commission (CPSC) found that the scientific evidence did not support this assumption. As in many environmental fields of study, the evidence is often disputed. Regulatory policy is not uniform on the subject of rock fragments, even within single agencies. The core of the issue is whether the risk parameters associated with exposures to commercial asbestos can or should be applied to rock fragments meeting an arbitrary set of particle dimensions used for counting asbestos fibers. Inappropriate inclusion of particles or fragments results in dilution of risk and needless expenditure of resources. On the other hand, inappropriate exclusion of particles or fragments may result in increased and unnecessary risk. Some of the fastest growing counties in the United States are in areas where NOA is known to exist and therefore this issue takes on national significance. This ongoing national dilemma has raised public and business concerns. There has been continuing political and scientific debate and widespread miscommunication over perceived versus actual health risks, the validity of various analytical sampling and testing methods, the questionable necessity and escalating costs of remediation procedures, and the combined negative impact on numerous commercial and public interests. Thus, conflicting research and regulatory positions on the distinctions between and hazards of true asbestos and ordinary rock fragments is all that is presently available to the public until the differing scientific communities and government agencies arrive at a consensus on these issues. The risk assessment methodology and the analytical technology needed to support inferences drawn from existing research are available, but have not been organized and implemented in the manner needed to resolve the NOA controversy. There should exist nationally adopted and peer-reviewed NOA standards (developed jointly by the scientific community, health risk professionals, and government regulators) that establish: (1) a scientific basis for risk evaluation and assessment of NOA and rock fragments; (2) accepted analytical protocols for determining if NOA actually exists in a given area and for separating NOA from related non-asbestos rock fragments and single crystal minerals; and (3) effective public policies for managing NOA, minimizing potential hazards, and protecting public health. This article will review some of the key issues involved with the current NOA debate, propose improved analytical methodologies, describe potential solutions for dealing with NOA, and outline the benefits to be gained by creating a practical national NOA public policy. PMID:18180100

Lee, R J; Strohmeier, B R; Bunker, K L; Van Orden, D R

2008-05-01

82

Probabilities of Natural Events Occurring at Savannah River Plant  

SciTech Connect

This report documents the comprehensive evaluation of probability models of natural events which are applicable to Savannah River Plant. The probability curves selected for these natural events are recommended to be used by all SRP/SRL safety analysts. This will ensure a consistency in analysis methodology for postulated SAR incidents involving natural phenomena.

Huang, J.C.

2001-07-17

83

Manufactured Home Testing in Simulated and Naturally Occurring High Winds  

SciTech Connect

A typical double-wide manufactured home was tested in simulated and naturally occurring high winds to understand structural behavior and improve performance during severe windstorms. Seven (7) lateral load tests were conducted on a double-wide manufactured home at a remote field test site in Wyoming. An extensive instrumentation package monitored the overall behavior of the home and collected data vital to validating computational software for the manufactured housing industry. The tests were designed to approach the design load of the home without causing structural damage, thus allowing the behavior of the home to be accessed when the home was later exposed to high winds (to 80-mph). The data generally show near-linear initial system response with significant non-linear behavior as the applied loads increase. Load transfer across the marriage line is primarily compression. Racking, while present, is very small. Interface slip and shear displacement along the marriage line are nearly insignificant. Horizontal global displacements reached 0.6 inch. These tests were designed primarily to collect data necessary to calibrate a desktop analysis and design software tool, MHTool, under development at the Idaho National Laboratory specifically for manufactured housing. Currently available analysis tools are, for the most part, based on methods developed for “stick built” structures and are inappropriate for manufactured homes. The special materials utilized in manufactured homes, such as rigid adhesives used in the connection of the sheathing materials to the studs, significantly alter the behavior of manufactured homes under lateral loads. Previous full scale tests of laterally loaded manufactured homes confirm the contention that conventional analysis methods are not applicable. System behavior dominates the structural action of manufactured homes and its prediction requires a three dimensional analysis of the complete unit, including tiedowns. This project was sponsored by the US Department of Energy, US Department of Housing and Urban Development, and the Manufactured Housing Institute. The results of this research can lead to savings in annual losses of life and property by providing validated information to enable the advancement of code requirements and by developing engineering software that can predict and optimize wind resistance.

W. D. Richins; T. K. Larson

2006-08-01

84

Absolute proof that hydrogen-antihydrogen oscillations occur in nature  

E-print Network

Detecting H-antiH oscillations is intimately connected with the existence of natural antiH. We detect natural H-antiH oscillations, generated by a classical spin-free Coulomb quantum gap, which we calculate analytically without any parameter. Oscillation times are much smaller than those predicted with the Standard Model. These unprecedented results also remove the so-called problem with matter-antimatter asymmetry in the Universe.

G. Van Hooydonk

2005-08-07

85

Natural and artificial alpha radioactivity of platinum isotopes  

NASA Astrophysics Data System (ADS)

The partial alpha emission half-life for the naturally occurring and artificially produced platinum isotopes (Z=78) was evaluated in the framework of a semiempirical, one-parameter model based on the quantum mechanical tunneling mechanism through a Coulomb-plus-centrifugal-plus-overlapping potential barrier within the spherical nucleus approximation. This approach has been shown to be exceptionally well suited (to a level of 90% of the cases within a factor of less than 2) to fitting the existing data covering nearly 23 orders of magnitude in the measured half-lives. Exceptions were found for the artificial alpha transition from 176Pt to the excited level of 172Os, and the rare, quite recently observed, case of the natural alpha decay of 190Pt to the first excited level of 186Os. Comparison with other alpha decay half-life estimates for the naturally occurring platinum isotopes has also been presented. In celebration of the centennial anniversary of the discovery of the atomic nucleus.

Tavares, O. A. P.; Medeiros, E. L.

2011-10-01

86

Biomimetic Nitration of Conjugated Linoleic Acid: Formation and Characterization of Naturally Occurring Conjugated Nitrodienes  

PubMed Central

Nitro-conjugated linoleic acids (NO2-cLA), endogenous nitrodiene lipids which act as inflammatory signaling mediators, were isolated and single isomers purified from the biomimetic acidic nitration products of conjugated linoleic acid (CLA). Structures were elucidated by means of detailed NMR and HPLC–MS/MS spectroscopic analysis and the relative double bond configurations assigned. Additional synthetic methods produced useful quantities and similar isomeric distributions of these unusual and reactive compounds for biological studies and isotopic standards, and the potential conversion of nitro-linoleic to nitro-conjugated linoleic acids was explored via a facile base-catalyzed isomerization. This represents one of the few descriptions of naturally occurring conjugated nitro dienes (in particular, 1-nitro 1,3-diene), an unusual and highly reactive motif with few biological examples extant. PMID:24350701

Woodcock, Steven R.; Salvatore, Sonia R.; Bonacci, Gustavo; Schopfer, Francisco J.; Freeman, Bruce A.

2014-01-01

87

Use of stable isotopes naturally occur-ring in dietary compounds for the study  

E-print Network

- fied by ion exchange. Neutral sugars were reduced and acetylated. Alditol acetates were separated. The metabolism of glycoprotein sugars and their nutritional regulation in man may be studied via dietary containing wheat starch (1.08692% !3C) as the only sugar source, then for 1 wk on the same diet containing

Paris-Sud XI, Université de

88

Overview of naturally occurring Earth materials and human health concerns  

NASA Astrophysics Data System (ADS)

The biosphere and the Earth's critical zone have maintained a dynamic equilibrium for more than 3.5 billion years. Except for solar energy, almost all terrestrial substances necessary for life have been derived from near-surface portions of the land, hydrosphere, and atmosphere. If aggregate biological activities are less than the rate of nutrient supply and/or resource renewal, sustained population growth is possible. Where the replenishment rate of a life-sustaining Earth material is finite, usage may reach a condition of dynamic equilibrium in which biological consumption equals but on average cannot exceed the overall supply. Although large, most natural resources are present in finite abundances; for such commodities, excessive present-day human utilization reduces future availability, and thus the ultimate planetary carrying capacity for civilization. Intensive use of Earth materials has enhanced the quality of life, especially in the developed nations. Still, natural background levels, and Earth processes such as volcanic eruptions, as well as human activities involving agriculture, construction, and the extraction, refining, and transformation of mineral resources have led to harmful side effects involving environmental degradation and public health hazards. Among naturally and anthropogenically induced risks are bioaccessible airborne dusts and gases, soluble pollutants in agricultural, industrial, and residential waters, and toxic chemical species in foods and manufactured products. At appropriate levels of ingestion, many Earth materials are necessary for existence, but underdoses and overdoses have mild to serious consequences for human health and longevity. This overview briefly sketches several natural resource health hazards. Included are volcanic ash + aerosols + gases, mineral dusts, non-volcanic aerosols + nanoparticles, asbestos + fibrous zeolites, arsenic, fluorine, iodine, uranium + thorium + radium + radon + polonium, selenium, mercury, copper, lead, chromium, and cadmium. Also noted are health effects of natural disasters, and an obligatory future sustainable consumption of natural resources. Not treated are the overwhelming adverse effects of malnutrition, lack of potable water, inadequate sanitation, fossil fuel usage, mining, manufacturing, and agricultural pollution, or environmental pathogens, nor are the important impacts of complex mixtures of Earth materials considered. With rise of the worldwide information network, economic globalization, and the industrial thrust of Developing Nations, the achievement of natural resource sustainability has emerged as a strategic imperative. Accompanying increased rates of Earth materials consumption and attendant environmental change, substantially improved, universal public health will require a major global effort, integrating collaborations among geoscientists, medical researchers, and epidemiologists. Governments and NGOs must provide important support of such cooperative efforts, and both health and Earth scientists must cross disciplinary and national boundaries.

Ernst, W. G.

2012-10-01

89

The Frequency, Nature, and Effects of Naturally Occurring Appearance-Focused Social Comparisons  

ERIC Educational Resources Information Center

This research examined the effects of naturally occurring appearance-focused social comparisons on women's affect, body satisfaction, and weight-related cognitions. During their daily activities, women reporting body dissatisfaction (n = 53) and women reporting body satisfaction (n = 34) recorded their reactions to comparison information.…

Leahey, Tricia M.; Crowther, Janis H.; Mickelson, Kristin D.

2007-01-01

90

Interactions between plasma proteins and naturally occurring polyphenols.  

PubMed

The plant natural products known as polyphenols are found at micronutrient levels in fruits, vegetables, and plant-based beverages such as wine, tea, coffee and cocoa. Consumption of a fruit- and vegetable-rich diet, the "Mediterranean diet", has been epidemiologically related to health benefits especially for chronic diseases including diabetes, cardiovascular disease, and Alzheimer's disease. The abundance of polyphenols in plant-rich diets, and the potent bioactivities of polyphenols, provide indirect evidence for a role for polyphenols in maintaining good health. However, molecular mechanisms for therapeutic or preventative activity have not been demonstrated in vivo. We summarize the chemical classes of natural polyphenols, their bioactivities and bioavailability and metabolism. Because many polyphenols bind protein, we focus on the potential of protein binding to mediate the health-related effects of polyphenols. We discuss interactions with plasma proteins as the first target organ past the digestive tract for these orally-ingested compounds. PMID:23330924

Li, Min; Hagerman, Ann E

2013-05-01

91

Going Wild: Lessons from Naturally Occurring T-Lymphotropic Lentiviruses  

PubMed Central

Over 40 nonhuman primate (NHP) species harbor species-specific simian immunodeficiency viruses (SIVs). Similarly, more than 20 species of nondomestic felids and African hyenids demonstrate seroreactivity against feline immunodeficiency virus (FIV) antigens. While it has been challenging to study the biological implications of nonfatal infections in natural populations, epidemiologic and clinical studies performed thus far have only rarely detected increased morbidity or impaired fecundity/survival of naturally infected SIV- or FIV-seropositive versus -seronegative animals. Cross-species transmissions of these agents are rare in nature but have been used to develop experimental systems to evaluate mechanisms of pathogenicity and to develop animal models of HIV/AIDS. Given that felids and primates are substantially evolutionarily removed yet demonstrate the same pattern of apparently nonpathogenic lentiviral infections, comparison of the biological behaviors of these viruses can yield important implications for host-lentiviral adaptation which are relevant to human HIV/AIDS infection. This review therefore evaluates similarities in epidemiology, lentiviral genotyping, pathogenicity, host immune responses, and cross-species transmission of FIVs and factors associated with the establishment of lentiviral infections in new species. This comparison of consistent patterns in lentivirus biology will expose new directions for scientific inquiry for understanding the basis for virulence versus avirulence. PMID:17041142

VandeWoude, Sue; Apetrei, Cristian

2006-01-01

92

Structures and Properties of Naturally Occurring Polyether Antibiotics  

PubMed Central

Polyether ionophores represent a large group of natural, biologically active substances produced by Streptomyces spp. They are lipid soluble and able to transport metal cations across cell membranes. Several of polyether ionophores are widely used as growth promoters in veterinary. Polyether antibiotics show a broad spectrum of bioactivity ranging from antibacterial, antifungal, antiparasitic, antiviral, and tumour cell cytotoxicity. Recently, it has been shown that some of these compounds are able to selectively kill cancer stem cells and multidrug-resistant cancer cells. Thus, they are recognized as new potential anticancer drugs. The biological activity of polyether ionophores is strictly connected with their molecular structure; therefore, the purpose of this paper is to present an overview of their formula, molecular structure, and properties. PMID:23586016

Rutkowski, Jacek; Brzezinski, Bogumil

2013-01-01

93

Serum concentration of sialic acids in naturally occurring ovine babesiosis.  

PubMed

This study is designated to assess the effect of the severity of Babesia ovis infection on sialic acid concentration in blood sera in naturally infected sheep. Infected animals (diseased group) comprised 38 Iranian fat-tailed sheep, about 1-3 years old, naturally infected with B. ovis, divided into four subgroups with respect to parasitemia rates (low 0.1-0.3 %, moderate 0.4-0.9 %, high 1-2.5 %, and very high >2.5 %). The parasitological diagnosis was confirmed using PCR analysis. As a control group, ten clinically healthy sheep reared under the same management and environmental conditions were also sampled. Hematological parameters and the concentrations of total sialic acid (TSA), lipid-bound sialic acid (LBSA), and protein-bound sialic acid (PBSA) were measured in both groups. Compared to controls, sialic acid concentrations showed significant increase (p?

Esmaeilnejad, Bijan; Tavassoli, Mousa; Asri-Rezaei, Siamak; Dalir-Naghadeh, Bahram; Abtahi Froushani, Seyyed Meysam; Arjmand, Jafar; Golabi, Mostafa

2014-10-01

94

Isolation and Spectral Analysis of Naturally Occurring Thiarubrine A  

NASA Astrophysics Data System (ADS)

We have designed an experiment in which students isolate and characterize thiarubrine A, a pseudo-antiaromatic 1,2-dithia-3,5-cyclohexadiene derivative. Thiarubrines are an important class of compounds which have recently received attention because of their unusual reactivity, unique biological activity, and potential medicinal applications. They possess a distinctive red color and structure features that are particularly useful for demonstrating UV-vis, NMR, and IR spectral analyses. A crude mixture containing thiarubrine A is obtained by methanol (liquid-solid) extraction of the roots of short ragweed, Ambrosia artemisiifolia. Alternatively, these compounds can be isolated from numerous taxa within the family Asteraceae. Thiarubrine A possesses alkyl, alkenyl, and alkynyl functionality, which is useful in illustrating the utility of IR and NMR in the characterization of natural products. The long wavelength UV-vis absorption band of thiarubrine is indication of the nonplanarity of dithiin ring and provides an excellent opportunity to discuss the concepts of aromaticity, conjugation, and molecular orbital theory.

Reyes, Juan; Morton, Melita; Downum, Kelsey; O'Shea, Kevin E.

2001-06-01

95

Evidence of sublaminar drag naturally occurring in a curved pipe  

NASA Astrophysics Data System (ADS)

Steady and unsteady flows in a mildly curved pipe for a wide range of Reynolds numbers are examined with direct numerical simulation. It is shown that in a range of Reynolds numbers in the vicinity of Reb ? 3400, based on bulk velocity and pipe diameter, a marginally turbulent flow is established in which the friction drag naturally reduces below the laminar solution at the same Reynolds number. The obtained values for friction drag for the laminar and turbulent (sublaminar) flows turn out to be in excellent agreement with experimental measurements in the literature. Our results are also in agreement with Fukagata et al. ["On the lower bound of net driving power in controlled duct flows," Phys. D 238, 1082 (2009)], as the lower bound of net power required to drive the flow, i.e., the pressure drop of the Stokes solution, is still lower than our marginally turbulent flow. A large-scale traveling structure that is thought to be responsible for that behaviour is identified in the instantaneous field. This mode could also be extracted using proper orthogonal decomposition. The effect of this mode is to redistribute the mean flow in the circular cross section which leads to lower gradients at the wall compared to the laminar flow.

Noorani, A.; Schlatter, P.

2015-03-01

96

Naturally Occurring Variants of the Dysglycemic Peptide Pancreastatin  

PubMed Central

Pancreastatin (PST), a chromogranin A-derived peptide, is a potent physiological inhibitor of glucose-induced insulin secretion. PST also triggers glycogenolysis in liver and reduces glucose uptake in adipocytes and hepatocytes. Here, we probed for genetic variations in PST sequence and identified two variants within its functionally important carboxyl terminus domain: E287K and G297S. To understand functional implications of these amino acid substitutions, we tested the effects of wild-type (PST-WT), PST-287K, and PST-297S peptides on various cellular processes/events. The rank order of efficacy to inhibit insulin-stimulated glucose uptake was: PST-297S > PST-287K > PST-WT. The PST peptides also displayed the same order of efficacy for enhancing intracellular nitric oxide and Ca2+ levels in various cell types. In addition, PST peptides activated gluconeogenic genes in the following order: PST-297S ? PST-287K > PST-WT. Consistent with these in vitro results, the common PST variant allele Ser-297 was associated with significantly higher (by ?17 mg/dl, as compared with the wild-type Gly-297 allele) plasma glucose level in our study population (n = 410). Molecular modeling and molecular dynamics simulations predicted the following rank order of ?-helical content: PST-297S > PST-287K > PST-WT. Corroboratively, circular dichroism analysis of PST peptides revealed significant differences in global structures (e.g. the order of propensity to form ?-helix was: PST-297S ? PST-287K > PST-WT). This study provides a molecular basis for enhanced potencies/efficacies of human PST variants (likely to occur in ?300 million people worldwide) and has quantitative implications for inter-individual variations in glucose/insulin homeostasis. PMID:24338022

Allu, Prasanna K. R.; Chirasani, Venkat R.; Ghosh, Dhiman; Mani, Anitha; Bera, Amal K.; Maji, Samir K.; Senapati, Sanjib; Mullasari, Ajit S.; Mahapatra, Nitish R.

2014-01-01

97

Naturally Occurring Orthopoxviruses: Potential for Recombination with Vaccine Vectors  

PubMed Central

Orthopoxviruses are being increasingly used as live recombinant vectors for vaccination against numerous infectious diseases in humans, domestic animals, and wildlife. For risk assessments and surveillance, information about the occurrence, distribution and ecology of orthopoxviruses in western Europe is important but has mainly been based on serological investigations. We have examined kidneys, lungs, spleens, and livers of Norwegian small rodents and common shrews (Sorex araneus) for the presence of orthopoxvirus DNA sequences by PCR with primers complementary to the viral thymidine kinase (TK) gene. PCR amplicons were verified as orthopoxvirus specific by hybridization with a vaccinia virus TK-specific probe. A total of 347 animals (1,388 organs) from eight locations in different parts of Norway, collected at different times of the year during 1993 to 1995, were examined. Fifty-two animals (15%) from five locations, up to 1,600 km apart, carried orthopoxvirus DNA in one or more of their organs, most frequently in the lungs. These included 9 of 68 (13%) bank voles (Clethrionomys glareolus), 4 of 13 (31%) gray-sided voles (Clethrionomys rufocanus), 3 of 11 (27%) northern red-backed voles (Clethrionomys rutilus), 16 of 76 (21%) wood mice (Apodemus sylvaticus), and 20 of 157 (13%) common shrews. The previous isolation of cowpox virus from two clinical cases of infection (human and feline) at two of the locations investigated suggests that the viruses detected are cowpox and that some of the virus-carrying small mammalian species should be included among the cowpox virus natural reservoir hosts in Scandinavia and western Europe. PMID:9705389

Sandvik, Tore; Tryland, Morten; Hansen, Hilde; Mehl, Reidar; Moens, Ugo; Olsvik, Ørjan; Traavik, Terje

1998-01-01

98

[Chemical investigation of naturally occurring drug materials. Elucidation of scientific basis for traditional medicines and exploitation of new naturally occurring drugs].  

PubMed

In search of new biologically active compounds in nature, we have been investigating naturally occurring substances on the following subjects: I. chemical studies on naturally occurring drug materials [a) elucidation of bioactive constituents in natural drugs, b) elucidation of scientific basis for crude drug processing, and c) investigation of bioactive constituents in food materials], II. exploitation of new pharmaceuticals in nature [a) investigation of marine natural products and b) exploitation of Indonesian medicinal plants], and III. synthetic studies on bioactive natural products [a) chemical modification of naturally abundant carbohydrates and terpenoids and b) synthetic studies of complex lipids]. This article reviews the results obtained in our laboratory since 1978 on the subjects of I-a, b, c, II-a, and III-a. PMID:1578342

Kitagawa, I

1992-01-01

99

Natural abundances of carbon isotopes in acetate from a coastal marine sediment  

NASA Technical Reports Server (NTRS)

Measurements of the natural abundances of carbon isotopes were made in acetate samples isolated from the anoxic marine sediment of Cape Lookout Bight, North Carolina. The typical value of the total acetate carbon isotope ratio (delta 13C) was -16.1 +/- 0.2 per mil. The methyl and carboxyl groups were determined to be -26.4 +/- 0.3 and -6.0 +/- 0.3 per mil, respectively, for one sample. The isotopic composition of the acetate is thought to have resulted from isotopic discriminations that occurred during the cycling of that molecule. Measurements of this type, which have not been made previously in the natural environment, may provide information about the dominant microbial pathways in anoxic sediments as well as the processes that influence the carbon isotopic composition of biogenic methane from many sources.

Blair, N. E.; Martens, C. S.; Des Marais, D. J.

1987-01-01

100

Distribution of naturally occurring radionuclides (U, Th) in Timahdit black shale (Morocco).  

PubMed

Attention has been focused recently on the use of Moroccan black oil shale as the raw material for production of a new type of adsorbent and its application to U and Th removal from contaminated wastewaters. The purpose of the present work is to provide a better understanding of the composition and structure of this shale and to determine its natural content in uranium and thorium. A black shale collected from Timahdit (Morocco) was analyzed by powder X-ray diffraction and SEM techniques. It was found that calcite, dolomite, quartz and clays constitute the main composition of the inorganic matrix. Pyrite crystals are also present. A selective leaching procedure, followed by radiochemical purification and alpha-counting, was performed to assess the distribution of naturally occurring radionuclides. Leaching results indicate that 238U, 235U, 234U, 232Th, 230Th and 228Th have multiple modes of occurrence in the shale. U is interpreted to have been concentrated under anaerobic conditions. An integrated isotopic approach showed the preferential mobilization of uranium carried by humic acids to carbonate and apatite phases. Th is partitioned between silicate minerals and pyrite. PMID:17098337

Galindo, C; Mougin, L; Fakhi, S; Nourreddine, A; Lamghari, A; Hannache, H

2007-01-01

101

Regional Patterns in the Isotopic Composition of Natural and  

E-print Network

regions has the potential to produce large groundwater NO3 - concentrations. The use of isotopes - in groundwater is fundamental to developing effective management plans intended to reduce nitrogen (N) inputsRegional Patterns in the Isotopic Composition of Natural and Anthropogenic Nitrate in Groundwater

102

Reassessing the stable isotope composition assigned to methane flux from natural wetlands in isotope-constrained budgets  

NASA Astrophysics Data System (ADS)

Stable isotope ratios in CH4 preserve information about its origin and history, and are commonly used to constrain global CH4 budgets. Wetlands are key contributors to the atmospheric burden of CH4 and typically are assigned a stable carbon isotope composition of ~-60 permil in isotope-weighted stable isotope models despite the considerable range of ?13C(CH4) values (~ -100 to -40 permil) known to occur in these diverse ecosystems. Kinetic isotope effects (KIEs) associated with the metabolism of CH4-producing microorganisms generate much of the natural variation but highly negative and positive ?13C(CH4) values generally result from secondary processes (e.g., diffusive transport or oxidation by soil methanotrophs). Despite these complexities, consistent patterns exist in the isotope composition of wetland CH4 that can be linked conclusively to trophic status and consequently, natural succession or human perturbations that impact nutrient levels. Another challenge for accurate representation of wetlands in carbon cycle models is parameterisation of sporadic CH4 emission events. Abrupt release of large volumes of CH4-rich bubbles in short periods of time can account for a significant proportion of the annual CH4 flux from a wetland but such events are difficult to detect using conventional methods. New infrared spectroscopy techniques capable of high temporal resolution measurements of CH4 concentration and stable isotope composition can readily quantify short-lived CH4 pulses. Moreover, the isotope data can be used conclusively to determine shifts in the mode of CH4 transport and provide the potential to link initiation of abrupt emission events to forcing by internal or external factors.

Hornibrook, Edward; Maxfield, Peter; Gauci, Vincent; Stott, Andrew

2013-04-01

103

CHARACTERIZATION OF CASEINS CROSSLINKED BY A NATURALLY OCCURRING CROSSLINKING AGENT-GENIPIN  

Technology Transfer Automated Retrieval System (TEKTRAN)

Increasing economic and environmental pressures demand more effective utilization of natural resources. Genipin, a naturally occurring crosslinking agent obtained from the fruit of Gardenia jasminoides, has recently attracted much attention due to its low cytotoxicity compared to traditional crossli...

104

INFLUENCE OF EASILY DEGRADABLE NATURALLY OCCURRING CARBON SUBSTRATES ON BIODEGRADATION OF MONOSUBSTITUTED PHENOLS BY AQUATIC BACTERIA  

EPA Science Inventory

The influence of readily degradable, naturally occurring carbon substrates on the biodegradation of several monosubstitued phenols (m-cresol, m-aminophenol, p-chlorophenol) was examined. The natural substrate classes used were amino acids, carbohydrates, and fatty acids. Samples ...

105

Mobilization of arsenic and other naturally occurring contaminants in groundwater of the Main Ethiopian Rift aquifers.  

PubMed

This study investigates the mechanisms of arsenic (As) and other naturally occurring contaminants (F(-), U, V, B, and Mo) mobilization from Quaternary sedimentary aquifers of the Main Ethiopian Rift (MER) and their enrichment in the local groundwater. The study is based on systematic measurements of major and trace elements as well as stable oxygen and hydrogen isotopes in groundwater, coupled with geochemical and mineralogical analyses of the aquifer rocks. The Rift Valley aquifer is composed of rhyolitic volcanics and Quaternary lacustrine sediments. X-ray fluorescence (XRF) results revealed that MER rhyolites (ash, tuff, pumice and ignimbrite) and sediments contain on average 72 wt. % and 65 wt. % SiO2, respectively. Petrographic studies of the rhyolites indicate predominance of volcanic glass, sanidine, pyroxene, Fe-oxides and plagioclase. The As content in the lacustrine sediments (mean = 6.6 mg/kg) was higher than that of the rhyolites (mean: 2.5 mg/kg). The lacustrine aquifers of the Ziway-Shala basin in the northern part of MER were identified as high As risk zones, where mean As concentration in groundwater was 22.4 ± 33.5 (range of 0.60-190 ?g/L) and 54% of samples had As above the WHO drinking water guideline value of 10 ?g/L. Field As speciation measurements showed that most of the groundwater samples contain predominantly (~80%) arsenate-As(V) over arsenite-As(III) species. The As speciation together with field data of redox potential (mean Eh = +73 ± 65 mV) and dissolved-O2 (6.6 ± 2.2 mg/L) suggest that the aquifer is predominantly oxidative. Water-rock interactions, including the dissolution of volcanic glass produces groundwater with near-neutral to alkaline pH (range 6.9-8.9), predominance of Na-HCO3 ions, and high concentration of SiO2 (mean: 85.8 ± 11.3 mg/L). The groundwater data show high positive correlation of As with Na, HCO3, U, B, V, and Mo (R(2) > 0.5; p < 0.001). Chemical modeling of the groundwater indicates that Fe-oxides and oxyhydroxides minerals were saturated in the groundwater, suggesting that the As reactivity is controlled by adsorption/desorption processes with these minerals. The data show that As and other oxyanion-forming elements such as U, B, Mo, and V had typically higher concentrations at pH > ~8, reflecting the pH-dependence of their mobilization. Based on the geochemical and stable isotope variations we have established a conceptual model for the occurrence of naturally occurring contaminants in MER groundwater: 1) regional groundwater recharge from the Highland, along the Rift margins, followed by lateral flow and water-rock interactions with the aquifer rocks resulted in a gradual increase of the salinity and naturally occurring contaminants towards the center of the valley; and (2) local ?(18)O-rich lake water recharge into adjacent shallow aquifers, followed by additional mobilization of As and other oxyanion-forming elements from the aquifer rocks. We posit that the combined physical-chemical conditions of the aquifers such as oxidizing state, Na-HCO3 composition, and pH>~8 lead to enhanced mobilization of oxyanion-forming elements from Fe-oxides and consequently contamination of local groundwater. These geochemical conditions characterize groundwater resources along the Eastern African Rift and thus constitute a potential threat to the quality of groundwater in larger areas of Eastern Africa. PMID:23899878

Rango, Tewodros; Vengosh, Avner; Dwyer, Gary; Bianchini, Gianluca

2013-10-01

106

Evidence of natural isotopic distribution from single-molecule SERS  

E-print Network

We report on the observation of the natural isotopic spread of carbon from single-molecule Surface Enhanced Raman Spectroscopy (SM-SERS). By choosing a dye molecule with a very localized Raman active vibration in a cyano bond (C$\\equiv$N triple bond), we observe (in a SERS colloidal liquid) a small fraction of SM-SERS events where the frequency of the cyano mode is softened and in agreement with the effect of substituting $^{12}$C by the next most abundant $^{13}$C isotope. This example adds another demonstration of single molecule sensitivity in SERS through isotopic editing which is done, in this case, not by artificial isotopic editing but rather by nature itself. It also highlights SERS as a unique spectroscopic tool, capable of detecting an isotopic change in one atom of a single molecule.

P. G. Etchegoin; E. C. Le Ru; M. Meyer

2008-11-03

107

Environmental and biomedical applications of natural metal stable isotope variations  

USGS Publications Warehouse

etal stable isotopes are now being used to trace metal contaminants in the environment and as indicators of human systemic function where metals play a role. Stable isotope abundance variations provide information about metal sources and the processes affecting metals in complex natural systems, complementing information gained from surrogate tracers, such as metal abundance ratios or biochemical markers of metal metabolism. The science is still in its infancy, but the results of initial studies confirm that metal stable isotopes can provide a powerful tool for forensic and biomedical investigations.

Bullen, T.D.; Walczyk, T.

2009-01-01

108

Nature of isomerism in exotic sulfur isotopes  

E-print Network

We clarify the origin of the anomalously hindered $E2$ decay from the $4^+_1$ level in $^{44}$S by performing a novel many-body analysis in the shell model. Within a unified picture about the occurrence of isomerism in neutron-rich sulfur isotopes, the $4^+_1$ state is demonstrated to be a $K=4$ isomer dominated by the two-quasiparticle configuration $\

Yutaka Utsuno; Noritaka Shimizu; Takaharu Otsuka; Tooru Yoshida; Yusuke Tsunoda

2014-12-30

109

Uranium pollution in an estuary affected by pyrite acid mine drainage and releases of naturally occurring radioactive materials.  

PubMed

After the termination of phosphogypsum discharges to the Huelva estuary (SW Spain), a unique opportunity was presented to study the response of a contaminated environmental compartment after the cessation of its main source of pollution. The evolution over time of uranium concentrations in the estuary is presented to supply new insights into the decontamination of a scenario affected by Naturally Occurring Radioactive Material (NORM) discharges. The cleaning of uranium isotopes from the area has not taken place as rapidly as expected due to leaching from phosphogypsum stacks. An in-depth study using various techniques of analysis, including (234)U/(238)U and (230)Th/(232)Th ratios and the decreasing rates of the uranium concentration, enabled a second source of uranium contamination to be discovered. Increased uranium levels due to acid mine drainage from pyrite mines located in the Iberian Pyrite Belt (SW Spain) prevent complete uranium decontamination and, therefore, result in levels nearly twice those of natural background levels. PMID:21529854

Villa, M; Manjón, G; Hurtado, S; García-Tenorio, R

2011-07-01

110

Inhibition of Gland Development in Insects by a Naturally Occurring Antiallatotropin ("Anti-Hormone")  

NSDL National Science Digital Library

The exercise will introduce the students to using chemical surgery as well as demonstrate the function of insect juvenile hormone and naturally occuring compounds in the interaction between insects and host plants.

Dorothy Feir (Saint Louis University; )

1981-06-07

111

REMOVAL OF ARSENIC FROM GROUNDWATER USING NATURALLY OCCURRING IRON OXIDES IN RURAL REGIONS OF MONGOLIA  

EPA Science Inventory

We have found that the iron oxide particles produced by grinding naturally occurring iron ores are very effective in removing arsenic from water. The arsenic adsorption isothermal of the particles h...

112

DECIPHERING NATURALLY-OCCURRING PB CONTAMINATION IMPACTING DRINKING WATER WELLS: SHAKER VILLAGE CATCHMENT, MAINE.  

EPA Science Inventory

Trace Pb concentrations in groundwater within glacial deposits across Maine fluctuate considerably. Deciphering the distribution and sources of naturally occurring Pb in groundwater with only the use of conventional anomaly identification techniques presents a challenge. In a rep...

113

In-situ remediation of naturally occurring radioactive materials with high-permeability hydraulic fracturing  

E-print Network

This thesis addresses the problem of removal of Naturally Occurring Radioactive Materials, NORM, and describes an effective alternative to the current treatment method for their removal. High-pen-meability fracturing, recently established...

Demarchos, Andronikos Stavros

1998-01-01

114

Naturally Occurring and Iatrogenic Animal Models of Valvular, Infectious, and Arrhythmic Cardiovascular Disease  

Microsoft Academic Search

Most naturally occurring congenital cardiovascular entities found in humans have been identified in one or more species of\\u000a animals but the utility of these naturally occurring models as research subjects is not well established. Many of the congenital\\u000a diseases are associated with noncardiovascular defects and some of these may result in infertility, impotence, and other reproductive\\u000a problems that preclude the

David R. Gross

115

Nature of isomerism in exotic sulfur isotopes.  

PubMed

We clarify the origin of the anomalously hindered E2 decay from the 4_{1}^{+} level in ^{44}S by performing a novel many-body analysis in the shell model. Within a unified picture about the occurrence of isomerism in neutron-rich sulfur isotopes, the 4_{1}^{+} state is demonstrated to be a K=4 isomer dominated by the two-quasiparticle configuration ??^{?}=1/2^{-}???^{?}=7/2^{-}. The 4_{1}^{+} state in ^{44}S is a new type of high-K isomer which has significant triaxiality. PMID:25658995

Utsuno, Yutaka; Shimizu, Noritaka; Otsuka, Takaharu; Yoshida, Tooru; Tsunoda, Yusuke

2015-01-23

116

Nature of Isomerism in Exotic Sulfur Isotopes  

NASA Astrophysics Data System (ADS)

We clarify the origin of the anomalously hindered E 2 decay from the 41+ level in 44S by performing a novel many-body analysis in the shell model. Within a unified picture about the occurrence of isomerism in neutron-rich sulfur isotopes, the 41+ state is demonstrated to be a K =4 isomer dominated by the two-quasiparticle configuration ? ??=1 /2-?? ??=7 /2- . The 41+ state in 44S is a new type of high-K isomer which has significant triaxiality.

Utsuno, Yutaka; Shimizu, Noritaka; Otsuka, Takaharu; Yoshida, Tooru; Tsunoda, Yusuke

2015-01-01

117

Mass transfer and carbon isotope evolution in natural water systems  

USGS Publications Warehouse

This paper presents a theoretical treatment of the evolution of the carbon isotopes C13 and C14 in natural waters and in precipitates which derive from such waters. The effects of an arbitrary number of sources (such as dissolution of carbonate minerals and oxidation of organic material) and sinks (such as mineral precipitation, CO2 degassing and production of methane), and of equilibrium fractionation between solid, gas and aqueous phases are considered. The results are expressed as equations relating changes in isotopic composition to changes in conventional carbonate chemistry. One implication of the equations is that the isotopic composition of an aqueous phase may approach a limiting value whenever there are simultaneous inputs and outputs of carbonate. In order to unambiguously interpret isotopic data from carbonate precipitates and identify reactants and products in reacting natural waters, it is essential that isotopic changes are determined chiefly by reactant and product stoichiometry, independent of reaction path. We demonstrate that this is so by means of quantitative examples. The evolution equations are applied to: 1. (1) carbon-14 dating of groundwaters; 2. (2) interpretation of the isotopic composition of carbonate precipitates, carbonate cements and diagenetically altered carbonates; and 3. (3) the identification of chemical reaction stoichiometry. These applications are illustrated by examples which show the variation of ??C13 in solutions and in precipitates formed under a variety of conditions involving incongruent dissolution, CO2 degassing, methane production and mineral precipitation. ?? 1978.

Wigley, T.M.L.; Plummer, L.N.; Pearson, F.J., Jr.

1978-01-01

118

Concentrations of the naturally occurring radionucleides Pb-210, Po-210, and Ra-226 in aquatic fauna  

NASA Technical Reports Server (NTRS)

Study reveals naturally occurring radionuclides are ubiquitous and contribute a substantial fraction of the natural radiation dose to humans and various biota. Measurements may be useful in ecological and other biological problems such as tracing food chains of animals and study of the metabolism of these elements.

Holtzman, R. B.

1969-01-01

119

Chemical constituents of peppers (Piper spp.) and application to food preservation: naturally occurring antioxidative compounds.  

PubMed Central

In a structure analysis of the compounds of the genus Piper (Family Piperaceae), we identified five phenolic amides from Piper nigrum, seven compounds from P. retrofractum, and two compounds from P. baccatum. All the phenolic amides possess significant antioxidant activities that are more effective than the naturally occurring antioxidant, alpha-tocopherol. One amide, feruperine, has antioxidant activity as high as the synthetic antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Naturally occurring antioxidants, therefore, may surpass BHA and BHT in their ability to inactivate mutagens in food. PMID:3757949

Nakatani, N; Inatani, R; Ohta, H; Nishioka, A

1986-01-01

120

Apoptosis and autophagy induction as mechanism of cancer prevention by naturally occurring dietary agents  

PubMed Central

Nontoxic naturally occurring compounds, especially those from dietary sources, are receiving increasing consideration for prevention and treatment of diseases including cancer. There is a growing need for innovative anticancer therapies and therefore search for natural compounds with novel biological activities or antineoplastic potential is currently an important area in drug discovery. Support for this interest also comes from increasing concern over the efficacy and safety of many conventional therapies, especially those that run over a long course of time. Laboratory studies in different in vitro and in vivo systems have shown that many natural compounds possess the capacity to regulate response to oxidative stress and DNA damage, suppress angiogenesis, inhibit cell proliferation and induce autophagy and apoptosis. This review discusses the induction of apoptosis and autophagy as a mechanism of cancer prevention by some of the most studied naturally occurring dietary compounds. PMID:23140293

Mukhtar, Eiman; Adhami, Vaqar Mustafa; Khan, Naghma; Mukhtar, Hasan

2013-01-01

121

A study of the dry heat resistance of naturally occurring organisms widely dispersed on a surface  

NASA Technical Reports Server (NTRS)

Although Bacillus subtilis var. niger is the standard test organism for NASA planetary quarantine sterilization studies, it was found that some naturally occurring soil organisms are more heat resistant. The separation of these organisms from soil particles is described. Experiments are discussed which were designed to show that the heat resistance is a natural characteristic of the organisms, rather than a condition induced by the clumping effect of agglomerated particles and organisms.

Garst, D. M.; Lindell, K. F.

1971-01-01

122

Recent progress regarding the bioactivities, biosynthesis and synthesis of naturally occurring resorcinolic macrolides.  

PubMed

Macrolides, which comprise a family of lactones with different ring sizes, belong to the polyketide class of natural products. Resorcinolic macrolides, an important subgroup, possess interesting structures and exhibit a wide variety of bioactivities, such as anti-tumor, anti-bacteria, and anti-malaria activities, etc. This review summarizes progress in isolation, bioactivity studies, biosynthesis, and representative chemical syntheses of this group of macrolides in recent decades, encompassing 63 naturally occurring macrolides published in 120 articles. PMID:24464049

Xu, Jing; Jiang, Cheng-shi; Zhang, Zai-long; Ma, Wen-quan; Guo, Yue-wei

2014-03-01

123

A naturally occurring brominated furanone covalently modifies and inactivates LuxS.  

PubMed

Halogenated furanones, a group of natural products initially isolated from marine red algae, are known to inhibit bacterial biofilm formation, swarming, and quorum sensing. However, their molecular targets and the precise mode of action remain elusive. Herein, we show that a naturally occurring brominated furanone covalently modifies and inactivates LuxS (S-ribosylhomocysteine lyase, EC 4.4.1.21), the enzyme which produces autoinducer-2 (AI-2). PMID:19775890

Zang, Tianzhu; Lee, Bobby W K; Cannon, Lisa M; Ritter, Kathryn A; Dai, Shujia; Ren, Dacheng; Wood, Thomas K; Zhou, Zhaohui Sunny

2009-11-01

124

Naturally occurring scrapie-like spongiform encephalopathy in five domestic cats  

Microsoft Academic Search

Naturally occurring transmissible spongiform encephalopathies have been recognised in sheep, man, mink, captive deer and cattle. Recently a similar disease was reported in a domestic cat. This paper describes the clinical and pathological findings in five cats with similar signs, including further observations on the original case. All the cats had a progressive, neurological disease involving locomotor disturbances, abnormal behaviour

JM Wyatt; GR Pearson; TN Smerdon; TJ Gruffydd-Jones; GA Wells; JW Wilesmith

1991-01-01

125

A radioimmunological assay for naturally occurring insect juvenile hormones using iodinated tracers  

E-print Network

A radioimmunological assay for naturally occurring insect juvenile hormones using iodinated tracers hormone (JH). The antigens were prepared by binding the JH's to human serum albumin. lodinated tracers.100 of BSA. The assay detection limit was 20 pg for all the three juvenile hormones. RIA sensitivity

Paris-Sud XI, Université de

126

Genome-wide architecture of reproductive isolation in a naturally occurring hybrid zone between Mus  

E-print Network

house mouse subspecies (Mus musculus musculus and M. m. domesticus) along with studies using laboratoryGenome-wide architecture of reproductive isolation in a naturally occurring hybrid zone between Mus musculus musculus and M. m. domesticus VA´ CLAV JANOUS EK,* LIUYANG WANG, KEN LUZYNSKI, PETRA DUFKOVA

Dean, Matthew D.

127

The element arsenic occurs naturally in dif-ferent forms, which may be classified  

E-print Network

, arsenic can be released from the Earth's crust into groundwater or surface water. Geothermal waters (e.g., "hot springs") also can release arsenic into groundwater, particularly in the Western United StatesThe element arsenic occurs naturally in dif- ferent forms, which may be classified either

128

Sign languages are naturally occurring languages used by members of deaf communities throughout the world.  

E-print Network

Sign languages are naturally occurring languages used by members of deaf communities throughout of vocal tract articula- tors, established sign languages display the full array of hierarchically of the present research was in sign­speech correspondence in the perceptual effects of language experience

129

Isolation of two novel candidate hormones using a chemical method for finding naturally occurring polypeptides  

Microsoft Academic Search

Naturally occurring peptides with biological actions have in most cases been detected by observing their biological activities in crude extracts and their isolation has been followed using bioassays. As a complement to the classical biological detection systems, we have proposed a chemical detection system based on fragmentation of peptides in tissue extracts followed by identification of certain of these peptide

Kazuhiko Tatemoto; Viktor Mutt

1980-01-01

130

Subject Reaction to Human-Caused and Naturally-Occurring Radioactive Threat.  

ERIC Educational Resources Information Center

While research has shown that people are adversely psychologically affected by knowledge that their communities have been toxically contaminated, it has been suggested that those who see a disaster as naturally occurring tend to be less adversely affected than those who see a disaster as caused by human acts. To examine this issue, questionnaires…

Belford, Susan; Gibbs, Margaret

131

Does Naturally Occurring Comprehension Strategies Instruction Make a Difference when Students Read Expository Text?  

ERIC Educational Resources Information Center

The present study examined whether observed differences in naturally occurring classroom instruction of reading comprehension strategies were reflected in students' independent use of strategies to comprehend expository text. Based on a descriptive classroom study in 4 ninth-grade language arts classrooms, participants were divided into two groups…

Braten, Ivar; Anmarkrud, Oistein

2013-01-01

132

NATURALLY OCCURRING SECONDARY NUTRITIONAL HYPERPARATHYROIDISM IN CATTLE EGRETS (BUBULCUS IBIS) FROM CENTRAL TEXAS  

Microsoft Academic Search

Naturally occurring secondary nutritional hyperparathyroidism is described in the nestlings of two colonies of cattle egrets (Bubulcus ibis) from Central Texas (Bryan and San Antonio, Texas, USA). Nestlings from a third colony (Waco, Texas, USA) were collected in a subsequent year for comparison. Birds from the first two colonies consistently had severe osteo- penia and associated curving deformities and folding

David N. Phalen; Mark L. Drew; Cindy Contreras; Kimberly Roset; Miguel Mora

133

MALDI-TOF Mass Spectrometry of Naturally-Occurring Mixtures of Mono- and Di-rhamnolipids  

Technology Transfer Automated Retrieval System (TEKTRAN)

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been developed for high-throughput screening of naturally-occurring mixtures of rhamnolipids from Pseudomonas spp. Mono- and di-rhamnolipids are readily distinguished by characteristic molecular adduct i...

134

Naturally occurring vapor-liquid-solid (VLS) Whisker growth of germanium sulfide  

USGS Publications Warehouse

The first naturally occurring terrestrial example of vapor-liquid-solid (VLS) growth has been observed in condensates from gases released by burning coal in culm banks. Scanning electron microscopy, X-ray diffraction, and energy dispersive analysis indicate that the crystals consist of elongated rods (??? 100 ??m) of germanium sulfide capped by bulbs depleted in germanium. ?? 1974.

Finkelman, R.B.; Larson, R.R.; Dwornik, E.J.

1974-01-01

135

On Their Own Turf: Community Design and Active Aging in a Naturally Occurring Retirement Community  

Microsoft Academic Search

This research examines neighborhood-scale physical and social environmental conditions that are associated with active living among seniors in Greendale, Wisconsin. The town's demographics reflect a naturally occurring retirement community. From survey responses of over 700 seniors, findings show that far more seniors reported walking for health and exercise reasons than for instrumental reasons or for social interaction. Senior Greendalers rarely

Sherry Ahrentzen

2010-01-01

136

Naturally Occurring Retirement Communities: Untapped Resources to Enable Optimal Aging at Home  

Microsoft Academic Search

Staying healthy, independent and happy in one's own home is one of the greatest challenges of aging. Naturally occurring retirement communities (NORCs) are untapped and underutilized resources that have the potential to optimize health, independence, and quality of life for older individuals in an economical way. This conceptual article describes the evolution (1996–2010) of the Cherryhill NORC (13 apartment buildings;

Marita Kloseck; Richard G. Crilly; Gloria M. Gutman

2010-01-01

137

Tasks, Teacher Feedback, and Learner Modified Output in Naturally Occurring Classroom Interaction  

ERIC Educational Resources Information Center

Tasks and interactional feedback have received much attention in instructed second language acquisition research in recent years. However, little research exists that has investigated feedback and task factors together during naturally occurring teacher-student interaction in classroom settings. To bridge this gap, the current study explored the…

Gurzynski-Weiss, Laura; Revesz, Andrea

2012-01-01

138

Sensitivity, child regulatory processes, and naturally occurring declines in antisocial behavior across childhood.  

PubMed

Despite considerable research on why antisocial behavior develops and interventions that reduce it, aspects of everyday family processes that may promote naturally occurring declines in antisocial behavior or that may result from such declines in most children without intervention are poorly understood. The current study explored family processes that may enable children to replace antisocial tendencies and the effects that declines in antisocial behavior may have on parenting and child regulatory processes. Longitudinal data from 1,022 children (54 months-6th grade) from the NICHD Study of Early Child Care and Youth Development were examined. Findings demonstrated that naturally occurring declines in antisocial behavior both predicted and were predicted by maternal sensitivity, emotion regulation, and social skills. These declines predicted but were not predicted by declines in hostile attributions. The data revealed multiple indirect paths, which highlight the complex nature of these variables across development. PMID:25221971

Buck, Katharine Ann

2014-12-01

139

Magnesium Isotope Fractionation By Chemical Diffusion In Natural Silicate Rocks  

NASA Astrophysics Data System (ADS)

The isotopic composition of geologic materials can be altered by natural processes in a number of different ways. Important information about the conditions and the processes that operated can be documented by studying the resulting fractionations. In this study, we document the fractionation of magnesium isotopes by chemical diffusion between coeval felsic and silicic magmas from the Vinal Cove complex of the Vinalhaven Intrusive Complex in Maine. Further, we show that the isotopic fractionation can be used to determine the extent of diffusive transport associated with particular geological processes. The Vinal Cove complex is dominated by felsic porphyry along with substantial volumes of contemporaneous mafic and hybrid rocks. The rocks of the Vinal Cove complex appear to record events during the waning stages of solidification of the Vinalhaven intrusive complex, when a large mafic dike intruded a small, partially molten inner portion of the mostly solidified, coarse-grained Vinalhaven granite (Wiebe et al., 2004). An approximately 20 cm thick zone of felsic porphyry between granite and basalt is thought to have formed by the thermal rejuvenation of a silicic crystal mush by a basaltic influx. The contact between the porphyry and the basalt is irregular and crenulate. The magnesium isotopic compositions of samples from two regions across this contact were measured. In addition, two experimental diffusion couples, made by juxtaposing powders of felsic porphyry and basalt from the natural sample from Vinal Cove, were also used to quantify and to compare the magnesium isotopic fractionations associated with chemical diffusion between the natural and experimental samples. The two diffusion couples were made by annealing the powders in a piston cylinder assembly at temperatures of 1450°C, pressures of 1450 kbar, and for 22.5 and 10 hours respectively. Chemical diffusion of magnesium from basalt to felsic porphyry was driven by a concentration ratio of between 4 and 5 in diffusion couples and the natural samples and produced a fractionation of 26Mg from 24Mg of between 2-3 ‰ in both, the two diffusion couples and in the two natural samples. The measured isotopic fractionations provide an estimate of the mass dependence of the diffusion coefficients of the magnesium isotopes corresponding to D26Mg/ D24Mg = (24/26)? with ? = 0.05. These results correspond with the experimental results and predictions of Richter et al. (2008) and shows that the degree of isotopic fractionation during chemical diffusion depends on the relative mobility of the isotopes (i.e. ?) and the concentration contrast between the interdiffusing melts and that its effect is the greatest in the region of low concentration. References Richter F. M., Watson E. B., Mendybaev R. A., Teng F-Z. and Janney P. E. (2008) Magnesium isotope fractionation in silicate melts by chemical and thermal diffusion. Geochem. Cosmochem. Acta 72, 206-220. Wiebe R. A., Manon M. R., Hawkins, D. P. and McDonough W. F. (2004) Late-stage mafic injection and thermal rejuvenation of the Vinalhaven granite, coastal Maine. J. Petrol. Vol. 45, 2133-2153.

Chopra, R.; Richter, F. M.; Watson, E. B.

2009-12-01

140

The analysis of naturally-occurring radionuclides from uranium and thorium decay series in table mineral waters.  

PubMed

This project required the highly sensitive analysis of low-level alpha- and beta-emitters naturally occurring in table mineral water sold on the Swiss market. These radionuclides occur in the three major decay series-uranium-238, uranium-235, and thorium-232. The radionuclides analysed were 238U, 235U, 234U, 232Th, 230Th, 228Th, 210Po, 210Pb, and 226Ra. Many other radionuclides were determinable as a result of their equilibrium with an analysed nuclide. Efficient, element specific separation techniques were developed, allowing for the spectral analysis of each element without interference from other radioactive elements. Radioactive tracers, 232U, 230Th, and 209Po, were necessary to determine the percentage yield. These yields often varied greatly between different mineral waters, especially for thorium, ranging from 30 to 100%. Uranium, thorium and polonium isotopes could be directly analysed for by alpha-spectrometry. 226Ra was determined through the ingrowth of its daughter 222Rn by liquid scintillation counting. From the samples remaining after 210Po removal, the isotope's re-ingrowth from 210Pb determined the original 210Pb content. Limits of detection ranged from 0.1 to 2.0 mBq/l. The following contents were determined 234U + 238U 30-720 mBq/l; 232Th + 230Th < 1-5 mBq/l; 228Th 2-40 mBq/l; 226Ra 5-370 mBq/l; 210Po 1-90 mBq/l; 2,0Pb 1-90 mBq/l. PMID:8469952

Aellen, T C; Umbricht, O; Goerlich, W

1993-03-25

141

Chapter 5. Conclusion Uranium, a naturally occurring element, contributes to low levels of natural background radiation in the  

E-print Network

5-1 Chapter 5. Conclusion Uranium, a naturally occurring element, contributes to low levels into uranium oxide or other chemical forms usable in industry. Uranium undergoes radioactive decay into a long are extracted from the earth. Protore is mined uranium ore that is not rich enough to meet the market demand

142

Isotopic distributions.  

PubMed

Isotopic information determined by mass spectrometry can be used in a wide variety of applications. Broadly speaking these could be classified as "passive" applications, meaning that they use naturally occurring isotopic information, and "active" applications, meaning that the isotopic distributions are manipulated in some way. The classic passive application is the determination of chemical composition by comparing observed isotopic patterns of molecules to theoretically calculated isotopic patterns. Active applications include isotope exchange experiments of a variety of types, as well as isotope labeling in tracing studies and to provide references for quantitation. Regardless of the type of application considered, the problem of theoretical calculation of isotopic patterns almost invariably arises. This paper reviews a number of application examples and computational approaches for isotopic studies in mass spectrometry. PMID:23666722

Rockwood, Alan L; Palmblad, Magnus

2013-01-01

143

Issues in the disposal of waste containing naturally occurring radioactive material.  

PubMed

This article considers a number of key issues in the disposal of waste containing enhanced levels of naturally occurring radioactive material (NORM), including gaseous, liquid and solid media. A brief review is made of sources of natural radioactivity in the biosphere and of anthropogenic enhancement of the concentration of NORM in the various media. The factors controlling the mobility of radionuclide activity in the environment are examined and disposal options are considered, comparison also being made with disposal of nuclear fuel cycle materials, in particular the tailings of uranium mining. Current and proposed disposal practices and policies for NORM are cited, reference being made to experiences in a number of countries. PMID:9451776

Bhattacharyya, D K

1998-03-01

144

ENVIRONMENTAL ISOTOPES FOR RESOLUTION OF HYDROLOGY PROBLEMS  

EPA Science Inventory

The use of environmental isotopes as tracers in the hydrosphere is increasing as analytical instrumentation improves and more applications are discovered. There exists still misconceptions on the role of isotopes in resolving hydrology problems. Naturally occurring isotopes in th...

145

Structural Consequences of Chromophore Formation and Exploration of Conserved Lid Residues amongst Naturally Occurring Fluorescent Proteins  

PubMed Central

Computational methods were used to generate the lowest energy conformations of the immature precyclized forms of the 28 naturally occurring GFP-like proteins deposited in the pdb. In all 28 GFP-like proteins, the beta-barrel contracts upon chromophore formation and becomes more rigid. Our prior analysis of over 260 distinct naturally occurring GFP-like proteins revealed that most of the conserved residues are located in the top and bottom of the barrel in the turns between the ?-sheets.(1) Structural analyses, molecular dynamics simulations and the Anisotropic Network Model were used to explore the role of these conserved lid residues as possible folding nuclei. Our results are internally consistent and show that the conserved residues in the top and bottom lids undergo relatively less translational movement than other lid residues, and a number of these residues may play an important role as hinges or folding nuclei in the fluorescent proteins. PMID:24465077

Zimmer, Matthew H.; Li, Binsen; Shahid, Ramza S.; Peshkepija, Paola; Zimmer, Marc

2014-01-01

146

Structural consequences of chromophore formation and exploration of conserved lid residues amongst naturally occurring fluorescent proteins  

NASA Astrophysics Data System (ADS)

Computational methods were used to generate the lowest energy conformations of the immature precyclized forms of the 28 naturally occurring GFP-like proteins deposited in the pdb. In all 28 GFP-like proteins, the beta-barrel contracts upon chromophore formation and becomes more rigid. Our prior analysis of over 260 distinct naturally occurring GFP-like proteins revealed that most of the conserved residues are located in the top and bottom of the barrel in the turns between the ?-sheets (Ong et al. 2011) [1]. Structural analyses, molecular dynamics simulations and the Anisotropic Network Model were used to explore the role of these conserved lid residues as possible folding nuclei. Our results are internally consistent and show that the conserved residues in the top and bottom lids undergo relatively less translational movement than other lid residues, and a number of these residues may play an important role as hinges or folding nuclei in the fluorescent proteins.

Zimmer, Matthew H.; Li, Binsen; Shahid, Ramza; Peshkepija, Paola; Zimmer, Marc

2014-01-01

147

Revising the proton affinity scale of the naturally occurring ? -amino acids  

Microsoft Academic Search

The proton affinities (PA) of the 20 naturally occurring ?-amino acids (AA) have been determined computationally by means of density functional theory (DFT) and high-level G2(MP2)\\u000a calculations. These theoretical PAs, together with data that have appeared since 1997 in the literature, are used to validate\\u000a the most reasonable currently available PA scale for AAs (Harrison, A. G. Mass Spectrom. Rev.

Christian Bleiholder; Sándor Suhai; Béla Paizs

2006-01-01

148

Pyrethroid insecticides: A naturally occurring toxin. (Latest citations from Pollution Abstracts). Published Search  

SciTech Connect

The bibliography contains citations concerning the effects of pyrethrum and pyrethroid insecticides. Topics examine toxicity to fish, worms, flies, mosquitoes, and moths. Chemical residue on crops, the transportation of pyrethrum from soils to crops, and pyrethrum accumulation in ponds and lakes are among the topics discussed. Naturally occurring and synthetic pyrethroid insecticides are included. (Contains a minimum of 173 citations and includes a subject term index and title list.)

Not Available

1993-05-01

149

Two naturally occurring deletion mutants of 12S seed storage proteins in Arabidopsis thaliana  

Microsoft Academic Search

Two naturally occurring Arabidopsis mutants, Cape Verde Islands and Monte (Mr-0), with aberrant 12S seed storage protein (SSP) profiles have been identified by SDS-PAGE. In both mutants, one of the 12S globulin bands is missing while a new band of lower molecular mass is present. Tandem mass spectrometry-mass spectrometry (MS\\/MS) analyses of the mutant peptides have revealed that both are

Anfu Hou; Kede Liu; Niramol Catawatcharakul; Xurong Tang; Vi Nguyen; Wilfred A. Keller; Edward W. T. Tsang; Yuhai Cui

2005-01-01

150

Polyporus tenuiculus : a new naturally occurring mushroom that can be industrially cultivated on agricultural waste  

Microsoft Academic Search

Polyporus tenuiculus is a naturally occurring species from Central and South America that is consumed by different ethnic groups in the region.\\u000a To determine the optimal conditions for fruiting body production, two strains were assayed on wheat straw and sawdust with\\u000a or without supplements. Sixty days of incubation at 25°C were needed to produce a solid block. The highest yield

Alejandra Omarini; Bernardo E. Lechner; Edgardo Albertó

2009-01-01

151

9-?-L(+) Adenosine: A new naturally occurring plant growth substance elicited by triacontanol in rice  

Microsoft Academic Search

The naturally occurring plant growth substance elicited by triacontanol was found to be 9-ß-L(+) adenosine by physical and spectral methods. At picomolar concentrations, 9-ß-L(+) adenosine stimulated growth as determined by dry weight measurements of several plant species. Reaction of adenosine deaminase with adenosine from rice showed that small quantities of 9-ß-L(+) adenosine exist in plants. We believe this is the

Stanley Ries; Violet Wert; N. F. D. O'Leary; Muraleedharan Nair

1990-01-01

152

The first naturally occurring thiepinols and thienol from an endolichenic fungus Coniochaeta sp.  

PubMed

Coniothiepinols A (1) and B (2) and coniothienol A (3), the first naturally occurring thiepinols (1 and 2) and thienol (3), have been isolated from the crude extract of an endolichenic fungus Coniochaeta sp. 1 possesses a unique 8-oxa-2-thia-bicyclo[3.2.1]octane skeleton, and its structure was assigned by NMR spectroscopy and X-ray crystallography. 1 showed significant activity against the gram-positive bacteria, Enterococcus faecium and Enterococcus faecalis. PMID:20919732

Wang, Yinchao; Niu, Shubin; Liu, Shuchun; Guo, Liangdong; Che, Yongsheng

2010-11-01

153

California Dept. of Toxic Substances Control (DTSC) Update of the Schools Naturally Occurring Asbestos Guidance  

NASA Astrophysics Data System (ADS)

Prior to acquisition and/or construction of prospective school sites, the California Education Code mandates that school districts complete environmental assessments and cleanups for prospective new or expanding school sites in order to qualify for state funding. If prospective school sites are determined to have environmental contamination from hazardous materials, including naturally occurring hazardous materials such as naturally occurring asbestos (NOA), where there may be unacceptable potential health risks, the school sites must be properly mitigated prior to occupancy for protection of human health and the environment. NOA is of special concern for schools, because children who are exposed to asbestos may be at increased risk of developing asbestos-related diseases over time. In order to protect human health, the Department of Toxic Substances Control's (DTSC) goals at school sites are to: 1) identify the presence of NOA in school site soils using exposure-reducing soil thresholds; 2) manage potential NOA exposures using mitigation measures to reduce generation of airborne asbestos fibers from soils on school sites; and 3) ensure long-term monitoring and protection of mitigation measures via Operations & Maintenance activities. DTSC is currently in the process of revising its Interim Guidance Naturally Occurring Asbestos (NOA) at School Sites - September 2004. The revisions include: 1) updating the guidance to consider incremental sampling for use at NOA sites in consultation with DTSC's project manager and technical staff, and 2) documenting a tiered approach to addressing high and low activity areas on a school.

Malinowski, M.

2012-12-01

154

15 N isotope biogeochemistry and natural denitrification process in groundwater: Application to the chalk aquifer of northern France  

Microsoft Academic Search

The use of 15 N natural isotope tracing in an aquifer contained within chalk rocks in northern France indicates that, under certain hydrogeological conditions, major denitrification occurs. At the boundary where the aquifer becomes confined, the nitrate concentrations decrease in the direction of groundwater flow accompanied by an exponential increase in 15 N (expressed in 15 N ) of the

André Mariotti; Alain Landreau; Béatrice Simon

1988-01-01

155

Intraspecific variation in testis asymmetry in birds: evidence for naturally occurring compensation  

PubMed Central

In many taxa, the left and right testes often differ in size. The compensation hypothesis states that one testis of the pair serves as a ‘back-up’ for any reduced function in the other and provides a mechanism to explain intraspecific variation in degree and direction of gonad asymmetry. Although testis asymmetry is common in birds, evidence for natural testis compensation is unknown. Using a novel quantitative approach that can be applied to any bilateral organ or structure, we show that testis compensation occurs naturally in birds and can be complete when one testis fails to develop. Owing to a recurrent risk of testis impairment and an evolutionary trade-off between natural and sexual selections acting on the arrangement of internal organs in species with abdominal and/or seasonal testes, compensation adds an important, but neglected, dimension to measures of male reproductive investment. PMID:19324740

Calhim, Sara; Birkhead, Tim R.

2009-01-01

156

Natural Ca Isotope Composition of Urine as a Rapid Measure of Bone Mineral Balance  

NASA Astrophysics Data System (ADS)

Naturally occurring stable Ca isotope variations in urine are emerging as a powerful tool to detect changes in bone mineral balance. Bone formation depletes soft tissue of light Ca isotopes while bone resorption releases isotopically light Ca into soft tissue. Previously published work found that variations in Ca isotope composition could be detected at 4 weeks of bed rest in a 90-day bed rest study (data collected at 4, 8 and 12 weeks). A new 30-day bed rest study involved 12 patients on a controlled diet, monitored for 7 days prior to bed rest and 7 days post bed rest. Samples of urine, blood and food were collected throughout the study. Four times daily blood samples and per void urine samples were collected to monitor diurnal or high frequency variations. An improved chemical purification protocol, followed by measurement using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) allowed accurate and precise determinations of mass-dependent Ca isotope variations in these biological samples to better than ±0.2% (?44/42Ca) on <25 ?g of Ca. Results from this new study show that Ca isotope ratios shift in a direction consistent with net bone loss after just 7 days, long before detectible changes in bone density by X-ray measurements occur. Consistent with this interpretation, the Ca isotope variations track changes observed in N-teleopeptide, a bone resorption biomarker. Bone-specific alkaline phosphatase, a bone formation biomarker, is unchanged over this period. Ca isotopes can in principle be used to quantify net changes in bone mass. Using a mass-balance model, our results indicate an average loss of 0.62 ± 0.16 % in bone mass over the course of this 30-day study. This is consistent with the rate of bone loss in longer-term studies as seen by X-ray measurements. This Ca isotope technique should accelerate the pace of discovery of new treatments for bone disease and provide novel insights into the dynamics of bone metabolism.

Skulan, J.; Gordon, G. W.; Morgan, J.; Romaniello, S. J.; Smith, S. M.; Anbar, A. D.

2011-12-01

157

Differentiation of naturally-occurring vs. artificial hydrocarbons in a landfill groundwater investigation  

SciTech Connect

Interpretation of groundwater sampling data at a large municipal/industrial landfill indicates contamination by both artificial and naturally-occurring hydrocarbons. Site hydrogeology consists of three different water bearing zones. The uppermost (shallow) aquifer is an unconfined unit consisting of silt, clay, and sand deposits. An intermediate depth semiconfined aquifer underlies the unconfined unit, and consists of a chert rubble zone and the upper portion of a fractured and solution-enhanced limestone formation. A regionally-extensive organic-rich shale underlies the semiconfined aquifer and separates it from the deep confined aquifer, which also consists of limestone. Groundwater investigations at the landfill have detected chlorinated and non-chlorinated hydrocarbons in the different aquifer intervals. Chlorinated hydrocarbons detected include tetrachloroethene, dichloroethene, and vinyl chloride and occur almost exclusively in the shallow aquifer. Aromatic hydrocarbons detected include benzene, toluene, ethylbenzene, and xylene (BTEX) and-occur in the intermediate and deep aquifers. The landfill was originally interpreted as the source of the contaminants. The observation of free-phase liquid hydrocarbons in the intermediate aquifer at the site, and high dissolved BTEX levels in the deep and intermediate aquifers upgradient of the landfill suggest that the aromatics were derived from a source other than the landfill. A potential source of BTEX contamination may be abandoned (pre-1930) natural gas wells located near the landfill. An additional BTEX source may be the organic-rich shale formation (a documented petroleum source rock).

Beaver, J.L.; Hartness, J.A.; Breeding, L.B.; Buchanan, D.M. [Law Environmental, Inc., Kennesaw, GA (United States)

1994-12-31

158

Naturally occurring arsenic in the groundwater at the Kansas City Plant  

SciTech Connect

This report describes an investigation concerning the presence of arsenic in concentrations exceeding 0.4 mg/L in the groundwater under the Department of Energy's Kansas City Plant (KCP). The study consisted of four distinct phases: a thorough review of the technical literature, a historical survey of arsenic use at the facility, a laboratory study of existing techniques for determining arsenic speciation, and a field program including water, soil, and sediment sampling. The historical survey and literature review demonstrated that plant activities had not released significant quantities of arsenic to the environment but that similar occurrences of arsenic in alluvial groundwater are widespread in the midwestern United States. Laboratory studies showed that a chromatographic separation technique was necessary to accurately determine arsenic speciation for the KCP groundwater samples. Field studies revealed that naturally occurring reducing conditions prevalent in the subsurface are responsible for dissolving arsenic previously sorbed by iron oxides. Indeed, the data demonstrated that the bulk arsenic concentration of site subsoils and sediments is {approximately}7 mg/kg, whereas the arsenic content of iron oxide subsamples is as high as 84 mg/kg. Literature showed that similar concentrations of arsenic in sediments occur naturally and are capable of producing the levels of arsenic found in groundwater monitoring wells at the KCP. The study concludes, therefore, that the arsenic present in the KCP groundwater is the result of natural phenomena. 44 refs., 8 figs., 14 tabs.

Korte, N.E.

1990-12-01

159

Biological activity of some naturally occurring resins, gums and pigments against in vitro LDL oxidation.  

PubMed

Naturally occurring gums and resins with beneficial pharmaceutical and nutraceutical properties were tested for their possible protective effect against copper-induced LDL oxidation in vitro. Chiosmastic gum (CMG) (Pistacia lentiscus var. Chia resin) was the most effective in protecting human LDL from oxidation. The minimum and maximum doses for the saturation phenomena of inhibition of LDL oxidation were 2.5 mg and 50 mg CMG (75.3% and 99.9%, respectively). The methanol/water extract of CMG was the most effective compared with other solvent combinations. CMG when fractionated in order to determine a structure-activity relationship showed that the total mastic essential oil, collofonium-like residue and acidic fractions of CMG exhibited a high protective activity ranging from 65.0% to 77.8%. The other natural gums and resins (CMG resin 'liquid collection', P. terebinthus var. Chia resin, dammar resin, acacia gum, tragacanth gum, storax gum) also tested as above, showed 27.0%-78.8% of the maximum LDL protection. The other naturally occurring substances, i.e. triterpenes (amyrin, oleanolic acid, ursolic acid, lupeol, 18-a-glycyrrhetinic acid) and hydroxynaphthoquinones (naphthazarin, shikonin and alkannin) showed 53.5%-78.8% and 27.0%-64.1% LDL protective activity, respectively. The combination effects (68.7%-76.2% LDL protection) of ursolic-, oleanolic- and ursodeoxycholic- acids were almost equal to the effect (75.3%) of the CMG extract in comparable doses. PMID:12748987

Andrikopoulos, Nikolaos K; Kaliora, Andriana C; Assimopoulou, Andreana N; Papapeorgiou, Vassilios P

2003-05-01

160

Naturally occurring progesterone in loblolly pine (Pinus taeda L.): a major steroid precursor of environmental androgens.  

PubMed

Progesterone, androstenedione, and androstadienedione were previously identified in the water and sediment of the Fenholloway River (Taylor County, FL, USA), a river that contains populations of masculinized female mosquitofish downstream of a paper mill, at levels higher than those in the nearby Spring Creek. Plant sterols, such as beta-sitosterol in mill effluent derived from pine tree pulp, were suggested to be metabolized by bacteria to progesterone and androgens to account for the masculinization phenomenon. The current study made use of standard solid-phase methanol extraction procedures, high-performance liquid chromatography, liquid chromatography-mass spectrometry, and a cell-based, androgen-receptor transcription assay to determine naturally occurring progesterone levels in mature pine trees. Progesterone concentrations in the loblolly pine (Pinus taeda L.) were 49.34 +/- 4.1 nmol/g dry mature wood (15.5 +/- 1.29 microg/g), 12.26 +/- 1.78 nmol/g pine needles (3.85 +/- 0.56 microg/g), and 3.81 +/- 0.36 nmol/g pine bark (1.19 +/- 0.11 mug/g). The results suggest that naturally occurring progesterone from pine wood pulp contributes to increased progesterone levels downstream of paper mill effluent discharges and may serve as the natural steroid precursor for environmental androgen production that causes masculinization of female mosquitofish. PMID:18229975

Carson, John D; Jenkins, Ronald L; Wilson, Elizabeth M; Howell, W Mike; Moore, Ray

2008-06-01

161

Activity measurements of technically enhanced naturally occurring radionuclides (TENORM) in phosphogypsum.  

PubMed

Phosphogypsum is a by-product of the phosphoric acid based fertilizer industry; it can be used in agriculture and to make building materials. Phosphogypsum is radioactive due to the presence of technically enhanced naturally occurring radionuclides (TENORM) and its environmental impact is a major concern of the public authorities. The Radionuclide Metrology Laboratory from IFIN-HH participated at the IAEA-CU-2007-06-CCRI(II)-S5 Supplementary Comparison for the Determination of TENORM in phosphogypsum. The measurement procedures and the discussion of results and problems encountered are presented. PMID:19231218

Luca, A; Margineanu, R; Sahagia, M; Wätjen, A C

2009-05-01

162

The new IAEA reference material: IAEA-434 technologically enhanced naturally occurring radioactive materials (TENORM) in phosphogypsum.  

PubMed

A reliable determination of Technologically Enhanced Naturally Occurring Radioactive Materials in phosphogypsum is necessary to comply with radiation protection and environmental regulations. In this respect, a new phosphogypsum reference material was produced and certified to assist in the validation of analytical methods and the quality assurance of produced analytical results. This paper presents the sample preparation methodology, material homogeneity assessment, characterization campaign results and assignment of property values, and associated uncertainties. The reference values and associated uncertainties for Pb-210, Ra-226, Th-230, U-234 and U-238 were established based on consensus values calculated from analytical results reported by three National Metrology Institutes and five expert laboratories. PMID:20869259

Shakhashiro, A; Sansone, U; Wershofen, H; Bollhöfer, A; Kim, C K; Kim, C S; Kis-Benedek, G; Korun, M; Moune, M; Lee, S H; Tarjan, S; Al-Masri, M S

2011-01-01

163

Towards the elusive structure of kotalanol, a naturally occurring glucosidase inhibitor.  

PubMed

This Highlight describes the detailed approach used to determine the absolute stereochemistry of the stereogenic centers in the acyclic side chain of kotalanol, a naturally occurring glucosidase inhibitor isolated from the plant Salacia reticulata. The plant extract itself is used in Ayurvedic medicine for the treatment of Type 2 diabetes. We highlight the syntheses of proposed candidates based on structure-activity relationships, the total synthesis of kotalanol, and crystallographic studies of kotalanol and its de-O-sulfonated derivative complexed with recombinant human maltase glucoamylase (MGA), a critical intestinal glucosidase involved in the breakdown of glucose oligomers into glucose. PMID:20336233

Mohan, Sankar; Pinto, B Mario

2010-04-01

164

First total synthesis of a naturally occurring iodinated 5'-deoxyxylofuranosyl marine nucleoside.  

PubMed

4-Amino-7-(5'-deoxy-?-D-xylofuranosyl)-5-iodo-pyrrolo[2,3-d]pyrimidine 1, an unusual naturally occurring marine nucleoside isolated from an ascidan, Diplosoma sp., was synthesized from D-xylose in seven steps with 28% overall yield on 10 g scale. The key step was Vorbrüggen glycosylation of 5-iodo-pyrrolo[2,3-d]pyrimidine with 5-deoxy-1,2-O-diacetyl-3-O-benzoyl-D-xylofuranose. Its absolute configuration was confirmed. PMID:22690148

Sun, Jianyun; Dou, Yanhui; Ding, Haixin; Yang, Ruchun; Sun, Qi; Xiao, Qiang

2012-04-01

165

First Total Synthesis of a Naturally Occurring Iodinated 5?-Deoxyxylofuranosyl Marine Nucleoside  

PubMed Central

4-Amino-7-(5?-deoxy-?-D-xylofuranosyl)-5-iodo-pyrrolo[2,3-d]pyrimidine 1, an unusual naturally occurring marine nucleoside isolated from an ascidan, Diplosoma sp., was synthesized from D-xylose in seven steps with 28% overall yield on 10 g scale. The key step was Vorbrüggen glycosylation of 5-iodo-pyrrolo[2,3-d]pyrimidine with 5-deoxy-1,2-O-diacetyl-3-O-benzoyl-D-xylofuranose. Its absolute configuration was confirmed. PMID:22690148

Sun, Jianyun; Dou, Yanhui; Ding, Haixin; Yang, Ruchun; Sun, Qi; Xiao, Qiang

2012-01-01

166

Evidence for a naturally occurring anti-spermine antibody in normal rabbit serum.  

PubMed Central

Normal rabbit serum contains an IgG-like component(s) that binds spermine as well as other polyamines. This molecule(s) has the same physicochemical properties as anti-spermine antibody obtained from rabbits immunized with spermine-thyroglobulin conjugates. However, the polyamines-binding IgG-like molecule(s), unlike anti-spermine antibody, is incapable either of precipitating a spermine-bovine serum albumin complex or of binding to a spermine-Sepharose column. These results suggest the existence of a naturally occurring anti-polyamine antibody that may have defective antibody functions. Images PMID:6930674

Furuichi, K; Ezoe, H; Obara, T; Oka, T

1980-01-01

167

Bibliography of reports, papers, and presentations on naturally occurring radioactive material (NORM) in petroleum industry wastes  

SciTech Connect

This bibliography was created to support projects conducted by Argonne National Laboratory (ANL) addressing issues related to naturally occurring radioactive material (NORM) in petroleum industry wastes. The bibliography provides citations for many of the available published reports, papers, articles, and presentations on petroleum industry NORM. In the past few years, the rapid expansion of NORM treatment and disposal technologies, the efforts to characterize NORM wastes and their associated potential risks, and the promulgation of state-level NORM regulatory programs have been well-documented in project reports and in papers presented at technical conferences and symposia. There are 221 citations.

Smith, K.P.; Wilkey, M.L.; Hames, R.D.

1997-07-01

168

Bay Area Air Quality Management District (BAAQMD) Naturally Occurring Asbestos Regulations and Enforcement Protocols  

NASA Astrophysics Data System (ADS)

BAAQMD has been delegated local enforcement of the Naturally-Occurring Asbestos Airborne Toxic Control Measure for Construction, Grading, Quarrying, and Surface Mining Operations, Section 93105, Title 17, California Code of Regulation ("NOA ATCM") by the state Air Resource Board. BAAQMD will present an overview of how BAAQMD administers and enforces the NOA ATCM, as well as a discussion of various issues that have arisen at NOA projects BAAQMD has overseen, and steps that have been taken in the interest of protecting the public health.

Wall, M.

2012-12-01

169

Naturally occurring and related synthetic cannabinoids and their potential therapeutic applications.  

PubMed

Naturally occurring cannabinoids (phytocannabinoids) are biosynthetically related terpenophenolic compounds uniquely produced by the highly variable plant, Cannabis sativa L. Natural and synthetic cannabinoids have been extensively studied since the discovery that the psychotropic effects of cannabis are mainly due to Delta(9)-THC. However, cannabinoids exert pharmacological actions on other biological systems such as the cardiovascular, immune and endocrine systems. Most of these effects have been attributed to the ability of these compounds to interact with the cannabinoid CB1 and CB2 receptors. The FDA approval of Marinol, a product containing synthetic Delta(9)-THC (dronabinol), in 1985 for the control of nausea and vomiting in cancer patients receiving chemotherapy, and in 1992 as an appetite stimulant for AIDS patients, has further intensified the research interest in these compounds. This article reviews patents (2003-2007) that describe methods for isolation of cannabinoids from cannabis, chemical and chromatographic methods for their purification, synthesis, and potential therapeutic applications of these compounds. PMID:19519560

Galal, Ahmed M; Slade, Desmond; Gul, Waseem; El-Alfy, Abir T; Ferreira, Daneel; Elsohly, Mahmoud A

2009-06-01

170

Molecular- and nm-scale Investigation of the Structure and Compositional Heterogeneity of Naturally Occurring Ferrihydrite  

NASA Astrophysics Data System (ADS)

Ferrihydrite is a hydrated Fe(III) nano-oxide that forms in vast quantities in contaminated acid mine drainage environments. As a result of its high surface area, ferrihydrite is an important environmental sorbent, and plays an essential role in the geochemical cycling of pollutant metal(loid)s in these settings. Despite its environmental relevance, this nanomineral remains one of the least understood environmental solids in terms of its structure (bulk and surface), compositional variations, and the factors affecting its reactivity. Under natural aqueous conditions, ferrihydrite often precipitates in the presence of several inorganic compounds such as aluminum, silica, arsenic, etc., or in the presence of organic matter. These impurities can affect the molecular-level structure of naturally occurring ferrihydrite, thus modifying fundamental properties that are directly correlated with solid-phase stability and surface reactivity. Currently there exists a significant gap in our understanding of the structure of synthetic vs. natural ferrihydrites, due to the inherent difficulties associated to the investigation of these poorly crystalline nanophases. In this study, we combined synchrotron- and laboratory-based techniques to characterize naturally occurring ferrihydrite from an acid mine drainage system situated at the New Idria mercury mine in California. We used high-energy X-ray total scattering and pair distribution function analysis to elucidate quantitative structural details of these samples. We have additionally used scanning transmission X-ray microscopy high resolution imaging (30 nm) to evaluate the spatial relationship of major elements Si, Al, and C within ferrihydrite. Al, Si and C K-edge near- edge X-ray absorption fine structure spectroscopy and 27Al nuclear magnetic resonance spectroscopy were used to obtain short-range structural information. By combining these techniques we attain the highest level of resolution permitted by current analytical methods to study such naturally occurring nanomaterials, both at the molecular- and nm-scale. This work provides structural information at the short-, medium- and long- range, as well as evidence of compositional heterogeneity, and mineral/organic matter associations.

Cismasu, C.; Michel, F. M.; Stebbins, J. F.; Tcaciuc, A. P.; Brown, G. E.

2008-12-01

171

Harnessing Naturally Occurring Tumor Immunity: A Clinical Vaccine Trial in Prostate Cancer  

PubMed Central

Background Studies of patients with paraneoplastic neurologic disorders (PND) have revealed that apoptotic tumor serves as a potential potent trigger for the initiation of naturally occurring tumor immunity. The purpose of this study was to assess the feasibility, safety, and immunogenicity of an apoptotic tumor-autologous dendritic cell (DC) vaccine. Methods and Findings We have modeled PND tumor immunity in a clinical trial in which apoptotic allogeneic prostate tumor cells were used to generate an apoptotic tumor-autologous dendritic cell vaccine. Twenty-four prostate cancer patients were immunized in a Phase I, randomized, single-blind, placebo-controlled study to assess the safety and immunogenicity of this vaccine. Vaccinations were safe and well tolerated. Importantly, we also found that the vaccine was immunogenic, inducing delayed type hypersensitivity (DTH) responses and CD4+ and CD8+ T cell proliferation, with no effect on FoxP3+ regulatory T cells. A statistically significant increase in T cell proliferation responses to prostate tumor cells in vitro (p?=?0.002), decrease in prostate specific antigen (PSA) slope (p?=?0.016), and a two-fold increase in PSA doubling time (p?=?0.003) were identified when we compared data before and after vaccination. Conclusions An apoptotic cancer cell vaccine modeled on naturally occurring tumor immune responses in PND patients provides a safe and immunogenic tumor vaccine. (ClinicalTrials.gov number NCT00289341). Trial Registration ClinicalTrials.gov NCT00289341 PMID:20824184

Tian, Suyan; Suárez-Fariñas, Mayte; Parveen, Salina; Blachère, Nathalie E.; Morris, Michael J.; Slovin, Susan; Scher, Howard I.; Albert, Matthew L.; Darnell, Robert B.

2010-01-01

172

A case of naturally occurring visual field loss in a chimpanzee with an arachnoid cyst.  

PubMed

Deficits in the occipital cortex have varying consequences among mammalian species. Such variations are indicative of evolutionary transitions in the striate cortical contribution to visually guided behavior. However, little is known about the role of the striate cortex in visually guided behavior in chimpanzees due to ethical concerns about invasive experiments and methodological limitations such as the inability to monitor gaze movements. We had the opportunity to study the behavioral consequences of a deficit in the occipital cortex in a chimpanzee with a naturally occurring arachnoid cyst in her right occipital lobe. We assessed the chimpanzee's ability to detect a small light probe (0.5 visual degree, Michelson contrast > 0.9) presented at several locations in the visual field while monitoring gaze direction using an infra-red remote eye-tracker recently introduced to studies of great apes. The results showed the chimpanzee was unable to detect the probe in the lower left quadrant of the visual field, suggesting severe loss of contrast sensitivity in a part of hemivisual field that is retinotopically corresponded to the hemisphere of the cyst. A chimpanzee with a naturally occurring deficit in the right striate cortex and the availability of remote eye-tracking technology presented a unique opportunity to compare the role of the occipital lobe in visually guided behavior among various primate species. PMID:24036355

Kaneko, Takaaki; Sakai, Tomoko; Miyabe-Nishiwaki, Takako; Tomonaga, Masaki

2013-11-01

173

The kinetics of rare earth element interactions with synthetic and naturally occurring polyelectrolytes  

SciTech Connect

This research is an investigation of the kinetics of formation and dissociation of complexes of trivalent lanthanide ions with the polyelectrolytes polyacrylic acid and humic acid. Theories of cation binding to charged polymers have defined two types of interactions: site binding, which involves complexation by a specific ligand group on the polyion, and territorial binding that is a non-specific, charge neutralization interaction. The speciation of trivalent lanthanides and actinides in the environment may be dominated by complexation with naturally occurring polymers. Therefore, knowledge of the rates of these interactions is important in modeling the environmental behavior of these cations in natural systems. Ultrafiltration and ion exchange studies indicate that under the conditions of this study, complexation is fast and complete, but slowly changes from the initially labile interactions to a distribution of the cations between labile sites and longer lived binding sites. This change in binding occurs by a cooperative binding mechanism that includes two processes. Relatively rapid diffusion of the metal ions into sites within the coiled structure of the polyion can occur along with slower polymer configurational changes that can create less labile, previously inaccessible sites. Decomplexation has been studied using a ligand exchange technique, and the binding sites appear to fall into two classes of interactions based on their dissociation rates. The first category of interactions dissociates rapidly, and presumably includes lanthanide ions bound to sites on the surface of the polymer as well as territorially bound cations. The second type of binding interactions is longer lived and may represent lanthanide ions complexed within the coiled structure of the polyion.

Clark, S.B.

1989-01-01

174

Reactive Neurogenesis in Response to Naturally Occurring Apoptosis in an Adult Brain  

PubMed Central

Neuronal birth and death are tightly coordinated to establish and maintain properly functioning neural circuits. Disruption of the equilibrium between neuronal birth and death following brain injury or pharmacological insult often induces reactive, and in some cases regenerative, neurogenesis. Many neurodegenerative disorders are not injury-induced, however, so it is critical to determine if and how reactive neurogenesis occurs under noninjury-induced neurodegenerative conditions. Here, we used a model of naturally occurring neural degradation in a neural circuit that controls song behavior in Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) and examined the temporal dynamics between neuronal birth and death. We found that during seasonal-like regression of the song, control nucleus HVC (proper name), caspase-mediated apoptosis increased within 2 d following transition from breeding to nonbreeding conditions and neural stem-cell proliferation in the nearby ventricular zone (VZ) increased shortly thereafter. We show that inhibiting caspase-mediated apoptosis in HVC decreased neural stem-cell proliferation in the VZ. In baseline conditions the extent of neural stem-cell proliferation correlated positively with the number of dying cells in HVC. We demonstrate that as apoptosis increased and the number of both recently born and pre-existing neurons in HVC decreased, the structure of song, a learned sensorimotor behavior, degraded. Our data illustrate that reactive neurogenesis is not limited to injury-induced neuronal death, but also can result from normally occurring degradation of a telencephalic neural circuit. PMID:25253853

Larson, Tracy A.; Thatra, Nivretta M.; Lee, Brian H.

2014-01-01

175

Reactive neurogenesis in response to naturally occurring apoptosis in an adult brain.  

PubMed

Neuronal birth and death are tightly coordinated to establish and maintain properly functioning neural circuits. Disruption of the equilibrium between neuronal birth and death following brain injury or pharmacological insult often induces reactive, and in some cases regenerative, neurogenesis. Many neurodegenerative disorders are not injury-induced, however, so it is critical to determine if and how reactive neurogenesis occurs under noninjury-induced neurodegenerative conditions. Here, we used a model of naturally occurring neural degradation in a neural circuit that controls song behavior in Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) and examined the temporal dynamics between neuronal birth and death. We found that during seasonal-like regression of the song, control nucleus HVC (proper name), caspase-mediated apoptosis increased within 2 d following transition from breeding to nonbreeding conditions and neural stem-cell proliferation in the nearby ventricular zone (VZ) increased shortly thereafter. We show that inhibiting caspase-mediated apoptosis in HVC decreased neural stem-cell proliferation in the VZ. In baseline conditions the extent of neural stem-cell proliferation correlated positively with the number of dying cells in HVC. We demonstrate that as apoptosis increased and the number of both recently born and pre-existing neurons in HVC decreased, the structure of song, a learned sensorimotor behavior, degraded. Our data illustrate that reactive neurogenesis is not limited to injury-induced neuronal death, but also can result from normally occurring degradation of a telencephalic neural circuit. PMID:25253853

Larson, Tracy A; Thatra, Nivretta M; Lee, Brian H; Brenowitz, Eliot A

2014-09-24

176

Background in the context of land contaminated with naturally occurring radioactive material.  

PubMed

The financial implications of choosing a particular threshold for clearance of radioactively contaminated land are substantial, particularly when one considers the volume of naturally occurring radioactive material (NORM) created each year by the production and combustion of fossil fuels and the exploitation of industrial minerals. Inevitably, a compromise needs to be reached between the level of environmental protection sought and the finite resources available for remediation. In the case of natural series radionuclides, any anthropogenic input is always superimposed on the inventory already present in the soil; this 'background' inventory is conventionally disregarded when assessing remediation targets. Unfortunately, the term is not well defined and the concept of 'background dose' is open to alternative interpretations. In this paper, we address the issue of natural background from a geochemical rather than from a solely radiological perspective, illustrating this with an example from the china clay industry. We propose a simple procedure for decision making based on activity concentrations of primordial radionuclides and their progeny. Subsequent calculations of dose need to take into account the mineralogical and chemical characteristics of the contamination, which in the case of NORM are invariably reflected in uranium series disequilibrium. PMID:23519083

Read, D; Read, G D; Thorne, M C

2013-06-01

177

NPACT: Naturally Occurring Plant-based Anti-cancer Compound-Activity-Target database  

PubMed Central

Plant-derived molecules have been highly valued by biomedical researchers and pharmaceutical companies for developing drugs, as they are thought to be optimized during evolution. Therefore, we have collected and compiled a central resource Naturally Occurring Plant-based Anti-cancer Compound-Activity-Target database (NPACT, http://crdd.osdd.net/raghava/npact/) that gathers the information related to experimentally validated plant-derived natural compounds exhibiting anti-cancerous activity (in vitro and in vivo), to complement the other databases. It currently contains 1574 compound entries, and each record provides information on their structure, manually curated published data on in vitro and in vivo experiments along with reference for users referral, inhibitory values (IC50/ED50/EC50/GI50), properties (physical, elemental and topological), cancer types, cell lines, protein targets, commercial suppliers and drug likeness of compounds. NPACT can easily be browsed or queried using various options, and an online similarity tool has also been made available. Further, to facilitate retrieval of existing data, each record is hyperlinked to similar databases like SuperNatural, Herbal Ingredients’ Targets, Comparative Toxicogenomics Database, PubChem and NCI-60 GI50 data. PMID:23203877

Mangal, Manu; Sagar, Parul; Singh, Harinder; Raghava, Gajendra P. S.; Agarwal, Subhash M.

2013-01-01

178

Naturally occurring and experimentally transmitted Hepatozoon americanum in coyotes from Oklahoma.  

PubMed

Twenty free-ranging coyotes (Canis latrans) in Oklahoma (USA) were examined for the presence of naturally occurring infections with Hepatozoon americanum and to determine if bone lesions attributable to H. americanum were present. Although eight of the 20 free-ranging coyotes were found to be naturally infected with H. americanum, no bone lesions were detected. In addition, two coyote pups were exposed to H. americanum oocysts collected from experimentally infected ticks and the course of the resulting infection was followed. Both experimentally infected coyotes developed hepatozoonosis detectable by specific muscle lesions beginning 4 wk after exposure. Bone lesions were detected grossly and histologically at necropsy. Histologic evidence of periosteal bone proliferation ranged from segmental areas of plump hypercellularity and thickening of the periosteum, with minor degrees of osteogenesis, to extensive proliferation of woven bone and periosteal hypercellularity and thickening. Nymphal Amblyomma maculatum that fed on one of the experimentally infected coyote pups became infected and mature H. americanum oocysts were recovered when the ticks molted to adults. These results demonstrate that coyotes in some parts of Oklahoma are naturally infected with H. americanum, that experimentally infected coyotes can develop clinical disease, including characteristic bone lesions, and that A. maculatum nymphs can acquire infections by feeding on them. PMID:10682757

Kocan, A A; Cummings, C A; Panciera, R J; Mathew, J S; Ewing, S A; Barker, R W

2000-01-01

179

2005 Nature Publishing Group In situ Os isotopes in abyssal peridotites bridge the  

E-print Network

© 2005 Nature Publishing Group In situ Os isotopes in abyssal peridotites bridge the isotopic gap Abyssal peridotites are assumed to represent the mantle residue of mid-ocean-ridge basalts (MORBs). However, the osmium isotopic compositions of abyssal peridotites and MORB do not appear

Demouchy, Sylvie

180

From phenotypic to molecular polymorphisms involved in naturally occurring variation of plant development.  

PubMed

An enormous amount of naturally occurring genetic variation affecting development is found within wild and domesticated plant species. This diversity is presumably involved in plant adaptation to different natural environments or in human preferences. In addition, such intraspecific variation provides the basis for the evolution of plant development at larger evolutionary scales. Natural phenotypic differences are now amenable to genetic dissection up to the identification of causal DNA polymorphisms. Here we describe 30 genes and their functional nucleotide polymorphisms currently found as underlying allelic variation accounting for plant intraspecific developmental diversity. These studies provide molecular and cellular mechanisms that determine natural variation for quantitative and qualitative traits such as: fruit and seed morphology, colour and composition; flowering time; seedling emergence; plant architecture and inflorescence or flower morphology. Besides, analyses of flowering time variation within several distant species allow molecular comparisons between species, which are detecting homologous genes with partly different functions and unrelated genes with analogous functions. Thus, considerable gene function differences are being revealed also among species. Inspection of a catalogue of intraspecific nucleotide functional polymorphisms shows that transcriptional regulators are the main class of genes involved. Furthermore, barely more than half of the polymorphisms described are located in coding regions and affect protein structure, while the rest are regulatory changes altering gene expression. These limited analyses of intraspecific developmental variation support Doebley and Lukens's proposition (1998) that modifications in cis -regulatory regions of transcriptional regulators represent a predominant mode for the evolution of novel forms, but await more detailed studies in wild plant species. PMID:16096977

Alonso-Blanco, Carlos; Mendez-Vigo, Belén; Koornneef, Maarten

2005-01-01

181

Beneficial Effects of Autologous Bone Marrow-Derived Mesenchymal Stem Cells in Naturally Occurring Tendinopathy  

PubMed Central

Tendon injuries are a common age-related degenerative condition where current treatment strategies fail to restore functionality and normal quality of life. This disease also occurs naturally in horses, with many similarities to human tendinopathy making it an ideal large animal model for human disease. Regenerative approaches are increasingly used to improve outcome involving mesenchymal stem cells (MSCs), supported by clinical data where injection of autologous bone marrow derived MSCs (BM-MSCs) suspended in marrow supernatant into injured tendons has halved the re-injury rate in racehorses. We hypothesized that stem cell therapy induces a matrix more closely resembling normal tendon than the fibrous scar tissue formed by natural repair. Twelve horses with career-ending naturally-occurring superficial digital flexor tendon injury were allocated randomly to treatment and control groups. 1X107 autologous BM-MSCs suspended in 2 ml of marrow supernatant were implanted into the damaged tendon of the treated group. The control group received the same volume of saline. Following a 6 month exercise programme horses were euthanized and tendons assessed for structural stiffness by non-destructive mechanical testing and for morphological and molecular composition. BM-MSC treated tendons exhibited statistically significant improvements in key parameters compared to saline-injected control tendons towards that of normal tendons and those in the contralateral limbs. Specifically, treated tendons had lower structural stiffness (p<0.05) although no significant difference in calculated modulus of elasticity, lower (improved) histological scoring of organisation (p<0.003) and crimp pattern (p<0.05), lower cellularity (p<0.007), DNA content (p<0.05), vascularity (p<0.03), water content (p<0.05), GAG content (p<0.05), and MMP-13 activity (p<0.02). Treatment with autologous MSCs in marrow supernatant therefore provides significant benefits compared to untreated tendon repair in enhancing normalisation of biomechanical, morphological, and compositional parameters. These data in natural disease, with no adverse findings, support the use of this treatment for human tendon injuries. PMID:24086616

Smith, Roger Kenneth Whealands; Werling, Natalie Jayne; Dakin, Stephanie Georgina; Alam, Rafiqul; Goodship, Allen E.; Dudhia, Jayesh

2013-01-01

182

Effect of genipin, a naturally occurring crosslinker on the properties of kappa-carrageenan.  

PubMed

Genipin-fixed kappa-carrageenan was prepared in ambient conditions in aqueous solution using genipin, a naturally occurring crosslinker with kappa-carrageenan (kappaC). The crosslinked kappaC showed the greatest swelling capacity in acidic medium having pH 1.2 when compared to those in neutral and alkaline media. Enhanced stability of the crosslinked product with respect to the non-modified kappaC was confirmed by degradation studies in Ringer's solution, rheological and thermogravimetric measurements. Genipin fixation of kappaC was confirmed by measuring the bulk density, true density, pore volume, porosity, intrinsic viscosity, UV absorbance and optical rotation of the crosslinked kappaC, and as well as by optical microscopy, SEM, and MS/MS studies. The crosslinked product may be useful as super absorbent and sustained release formulation in biomedical applications. PMID:17339049

Meena, Ramavatar; Prasad, Kamalesh; Siddhanta, A K

2007-06-01

183

Optimal conditions for the fruit body production of natural occurring strains of Lentinus tigrinus.  

PubMed

Lentinus tigrinus is a species with a fleshy pileus, strong odor and agreeable taste. In order to determine the optimal conditions for the production of this species, three substrates based on Salix sp. sawdust, wheat straw and supplements were tested in 500g dry weight bags at two different fruiting temperatures. Naturally occurring strains of this species were incubated at 30 degrees C. Primordium initiation could be observed 11-16 days after induction conditions began. This species produced highest yields with biological efficiency (BE) of 62% with supplemented sawdust at 25 degrees C. When bags were reduced to 100g dry weight, spawning run time was reduced from 28 to 30 to 10 to 14 days and BE increased more than 100%. L. tigrinus is a promising species with possibilities for commercial production. PMID:17239586

Lechner, Bernardo E; Albertó, Edgardo

2007-07-01

184

Naturally occurring Parelaphostrongylus tenuis-associated choriomeningitis in a guinea pig with neurologic signs.  

PubMed

An adult male guinea pig (Cavia porcellus) with a 1-month history of hind limb paresis, torticollis, and seizures was euthanized and submitted for necropsy. Gross examination was unremarkable, but histologic examination revealed multifocal eosinophilic and lymphoplasmacytic choriomeningitis and cross sections of nematode parasites within the leptomeninges of the midbrain and diencephalon. Morphologic features of the nematode were consistent with a metastrongyle, and the parasite was identified as Parelaphostrongylus tenuis by polymerase chain reaction testing and nucleotide sequencing. Further questioning of the owner revealed that the guinea pig was fed grass from a yard often grazed by white-tailed deer (Odocoileus virginianus). To the authors' knowledge, this is the first report of a naturally occurring P. tenuis infection in a guinea pig. PMID:23238578

Southard, T; Bender, H; Wade, S E; Grunenwald, C; Gerhold, R W

2013-05-01

185

Naturally occurring radioactive materials (NORM): a matter of wide societal implication.  

PubMed

Naturally occurring radioactive materials are ubiquitous on Earth and their radioactivity may become concentrated as a result of human activities. Numerous industries produce concentrated radioactivity in their by-products: the coal industry, petroleum extraction and processing, water treatment, etc. The present reference system of radiation protection does not provide a complete framework for the coherent management of all types of radioactively contaminated materials. Inconsistencies in waste management policy and practice can be noted across the board, and especially vis-à-vis the management of radioactive waste from the nuclear industry. This article reviews the present societal approach to manage materials that are radioactive but are often not recognised as being such, and place the management of radioactive materials from the nuclear industry in perspective. PMID:11302258

Pescatore, C; Menon, S

2000-12-01

186

Systems and methods for facilitating hydrogen storage using naturally occurring nanostructure assemblies  

DOEpatents

Some or all of the needs above can be addressed by embodiments of the invention. According to embodiments of the invention, systems and methods for facilitating hydrogen storage using naturally occurring nanostructure assemblies can be implemented. In one embodiment, a method for storing hydrogen can be provided. The method can include providing diatoms comprising diatomaceous earth or diatoms from a predefined culture. In addition, the method can include heating the diatoms in a sealed environment in the presence of at least one of titanium, a transition metal, or a noble metal to provide a porous hydrogen storage medium. Furthermore, the method can include exposing the porous hydrogen storage medium to hydrogen. In addition, the method can include storing at least a portion of the hydrogen in the porous hydrogen storage medium.

Fliermans; , Carl B. (Augusta, GA)

2012-08-07

187

Naturally occurring spore particles at planar fluid interfaces and in emulsions.  

PubMed

We have investigated the potential of utilizing naturally occurring spore particles of Lycopodium clavatum as sole emulsifiers of oil and water mixtures. The preferred emulsions, prepared from either oil-borne or aqueous-borne dispersions of the monodispersed particles of diameter 30 microm, are oil-in-water. The particles act as efficient stabilizers for oils of different polarity. Droplets as large as several millimeters are stable to coalescence indefinitely, despite the low coverage of interfaces by particles observed microscopically. Consistent with the emulsion findings, we discover that particles spontaneously adsorb to bare oil-water interfaces of single drops from oil dispersions, whereas adsorption is less spontaneous and extensive from aqueous dispersions. Monolayers of the spore particles at both air-water and oil-water planar interfaces contain particles in an aggregated state forming clusters and chains. The influence of particle concentration, oil/water ratio, and additives in the aqueous phase is studied. PMID:16114917

Binks, B P; Clint, J H; Mackenzie, G; Simcock, C; Whitby, C P

2005-08-30

188

Healthy Naturally Occurring Retirement Communities: A Low-Cost Approach to Facilitating Healthy Aging  

PubMed Central

Naturally occurring retirement communities (NORCs) are broadly defined as communities where individuals either remain or move when they retire. Using the determinants of health model as a base, we hypothesize that some environmental determinants have a different impact on people at different ages. Health benefits to living within NORCs have been observed and likely vary depending upon where the specific NORC exists on the NORC to healthy-NORC spectrum. Some NORC environments are healthier than others for seniors, because the NORC environment has characteristics associated with better health for seniors. Health benefits within healthy NORCs are higher where physical and social environments facilitate greater activity and promote feelings of well-being. Compared to the provision of additional medical or social services, healthy NORCs are a low-cost community-level approach to facilitating healthy aging. Municipal governments should pursue policies that stimulate and support the development of healthy NORCs. PMID:16735634

Masotti, Paul J.; Fick, Robert; Johnson-Masotti, Ana; MacLeod, Stuart

2006-01-01

189

Naturally occurring Tyzzer's disease in cotton-top tamarins (Saguinus oedipus).  

PubMed

We noted naturally occurring infection with Clostridium piliforme (Tyzzer's disease) in 2 captive-reared cotton-top tamarins (Saguinus oedipus). Spontaneous Tyzzer's disease has been reported in multiple species of laboratory, domestic, and wild animals but is extremely rare in humans and nonhuman primates. Distinct from idiopathic colitis, which is common in cotton-top tamarins, these 2 tamarins had severe, transmural, necrotizing typhlocolitis accompanied by myocarditis and hepatitis. Abundant bacteria compatible with C. piliforme, the etiologic agent of Tyzzer's disease, were present adjacent to lesions in the cecum-colon, liver, and heart. Therefore, colitis caused by C. piliforme, although rare, should be included as a differential diagnosis in cotton-top tamarins and as a cause of postnatal mortality in this species. PMID:17348301

Sasseville, Vito G; Simon, Meredith A; Chalifoux, Laura V; Lin, Kuei-Chin; Mansfield, Keith G

2007-02-01

190

Using ²²²Rn as a naturally occurring tracer to estimate NAPL contamination in an aquifer.  

PubMed

The naturally occurring radioisotope (222)Rn was used as a partitioning tracer to evaluate the presence and amount of a non-aqueous phase liquid (NAPL) in an aquifer. The batch experiment results of a diesel contaminated soil showed that the emanation rate of (222)Rn decreased to 31%, relative to a background rate. Batch experiment results of water contaminated by gasoline, diesel, PCE and TCE were similar. A field study to examine TCE contamination was conducted using 54 groundwater samples in Wonju city, Republic of Korea. Estimates of TCE contamination ranged from <0.001 mg/L to 14.3mg/L, and (222)Rn concentrations ranged from 1.89 Bq/L to 444. Results of (222)Rn analysis showed that TCE contamination was mainly restricted to an asphalt laboratory area and that the (222)Rn values of a NAPL-contaminated aquifer were correlated with TCE analytical results. PMID:23602707

Yoon, Yoon Yeol; Koh, Dong Chan; Lee, Kil Yong; Cho, Soo Young; Yang, Jae Ha; Lee, Kang Kun

2013-11-01

191

Analysis of naturally-occurring radionuclides in coal combustion fly ash, gypsum, and scrubber residue samples.  

PubMed

Coal combustion residues from coal-fired power plants can be advantageous for use in building and construction materials. These by-products contain trace quantities of naturally occurring radionuclides from the uranium and thorium series, as well as other naturally occurring radionuclides such as K. Analysis was performed on samples of coal fly ash, flue gas desulfurization, gypsum and scrubber sludges, fixated scrubber sludges, and waste water filter cakes sampled from multiple coal-fired power plants in the United States. The radioactive content of U and Th decay series nuclides was determined using gamma photopeaks from progeny Pb at 352 keV and Tl at 583 keV, respectively; K specific activities were determined using the 1,461 keV photopeak. The samples were hermetically sealed to allow for secular equilibrium between the radium parents and the radon and subsequent progeny. Samples were analyzed in a common geometry using two high purity germanium photon detectors with low energy detection capabilities. The specific activities (Bq kg) were compared to results from literature studies including different building materials and fly ash specific activities. Fly ash from bituminous and subbituminous coals had U specific activities varying from 30-217 Bq kg (mean + 1 s.d. 119 ± 45 Bq kg) and 72-209 Bq kg (115 ± 40 Bq kg), respectively; Th specific activities from 10-120 Bq kg (73 ± 26 Bq kg) and 53-110 Bq kg (81 ± 18 Bq kg), respectively; and K specific activities from 177 to 928 Bq kg (569 ± 184 Bq kg) and 87-303 Bq kg (171 ± 69 Bq kg), respectively. Gypsum samples had U, Th, and K specific activities approximately one order of magnitude less than measured for fly ash samples. PMID:23361421

Roper, Angela R; Stabin, Michael G; Delapp, Rossane C; Kosson, David S

2013-03-01

192

Biased Signaling in Naturally Occurring Mutations in Human Melanocortin-3 Receptor Gene  

PubMed Central

The melanocortin-3 receptor (MC3R) is primarily expressed in the hypothalamus and plays an important role in the regulation of energy homeostasis. Recently, some studies demonstrated that MC3R also signals through mitogen-activated protein kinases (MAPKs), especially extracellular signal-regulated kinases 1 and 2 (ERK1/2). ERK1/2 signaling is known to alter gene expression, potentially contributing to the prolonged action of melanocortins on energy homeostasis regulation. In the present study, we performed detailed functional studies on 8 novel naturally occurring MC3R mutations recently reported, and the effects of endogenous MC3R agonist, ?-melanocyte stimulating hormone (MSH), on ERK1/2 signaling on all 22 naturally occurring MC3R mutations reported to date. We found that mutants D158Y and L299V were potential pathogenic causes to obesity. Four residues, F82, D158, L249 and L299, played critical roles in different aspects of MC3R function. ?-MSH exhibited balanced activity in Gs-cAMP and ERK1/2 signaling pathways in 15 of the 22 mutant MC3Rs. The other 7 mutant MC3Rs were biased to either one of the signaling pathways. In summary, we provided novel data about the structure-function relationship of MC3R, identifying residues important for receptor function. We also demonstrated that some mutations exhibited biased signaling, preferentially activating one intracellular signaling pathway, adding a new layer of complexity to MC3R pharmacology. PMID:25798062

Yang, Fan; Huang, Hui; Tao, Ya-Xiong

2015-01-01

193

Natural thorium isotopes in marine sediment core off Labuan port  

SciTech Connect

Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.

Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R. [School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600, Bangi, Selangor (Malaysia)

2014-02-12

194

Naturally occurring neuronal plasticity in visual wulst of the Baya weaver, Ploceus philippinus (Linnaeus, 1766).  

PubMed

The visual wulst (VW), the rostro-dorsal surface of the avian telencephalon extending from the midline to the lateral region of the brain, is a laminated "bulge" consisting in four histologically distinct rostro-caudally arranged laminae with a specific sequence: hyperpallium apicale, interstitial nucleus of hyperpallium apicale, hyperpallium intercalatum and hyperpallium densocellulare. The VW has been proposed to be the avian equivalent of the mammalian striate cortex. Various behavioral studies including lesion experiments have indicated the importance of the VW, which receives visual and/or auditory cues. We have investigated qualitatively and quantitatively the fascinating structural changes occurring in VW neurons of the seasonally breeding bird, Ploceus philippinus (Linnaeus, 1766). The Golgi method was used to study the seasonal fluctuations in the neuronal classes of the VW with regard to dendritic thickness, spine morphology and spine density during both the non-breeding and breeding periods of male Baya weaver birds. Significant variations in parameters studied among the various neuronal types located in the different well-demarcated regions of the VW are believed to contribute to the functional differences reported among the wulst regions. Thus, this study extends our view demonstrating naturally occurring neuronal plasticity in a seasonally dynamic avian brain of a bird that hones not only its learning and memorizing system but also its social and sexual system in preparation for the breeding season. PMID:23435992

Srivastava, U C; Gaur, Parul

2013-06-01

195

Two naturally occurring deletion mutants of 12S seed storage proteins in Arabidopsis thaliana.  

PubMed

Two naturally occurring Arabidopsis mutants, Cape Verde Islands and Monte (Mr-0), with aberrant 12S seed storage protein (SSP) profiles have been identified by SDS-PAGE. In both mutants, one of the 12S globulin bands is missing while a new band of lower molecular mass is present. Tandem mass spectrometry-mass spectrometry (MS/MS) analyses of the mutant peptides have revealed that both are shorter variants of 12S globulin with deletion sites detected within the alpha-subunits of 12S globulin cruciferin B (CRB) and C (CRC), respectively. Sequence analyses of the genomic DNA flanking the deletion sites have demonstrated that both deletions occurred at the genomic level. These two mutants are referred to as CRBDelta12 and CRCDelta13 with the delta sign indicating a deletion and the number indicating amino acids deleted. Alignment of these two mutant sequences with that of soybean A3B4 subunit, for which the crystal structure was determined recently, have revealed that the CRCDelta13 deletion is located in a hypervariable/disordered region, and will probably not affect the structure of the hexameric globulin. The CRBDelta12 deletion, however, is located in a binding region that is thought to be important for the hexamer formation. However, CRBDelta12 appears to accumulate normally as judged by its band intensity relative to the other SSP subunits on the protein gels. Thus it seems that the seed can, to a certain extent, tolerate some mutations in its storage proteins. PMID:15912356

Hou, Anfu; Liu, Kede; Catawatcharakul, Niramol; Tang, Xurong; Nguyen, Vi; Keller, Wilfred A; Tsang, Edward W T; Cui, Yuhai

2005-10-01

196

The MTAP-CDKN2A Locus Confers Susceptibility to a Naturally Occurring Canine Cancer  

PubMed Central

Background Advantages offered by canine population substructure, combined with clinical presentations similar to human disorders, makes the dog an attractive system for studies of cancer genetics. Cancers that have been difficult to study in human families or populations are of particular interest. Histiocytic sarcoma is a rare and poorly understood neoplasm in humans that occurs in 15–25% of Bernese Mountain Dogs (BMD). Methods Genomic DNA was collected from affected and unaffected BMD in North America (NA) and Europe. Both independent and combined genome wide association studies (GWAS) were used to identify cancer-associated loci. Fine mapping and sequencing narrowed the primary locus to a single gene region. Results Both populations shared the same primary locus, which features a single haplotype spanning MTAP and part of CDKN2A and is present in 96% of affected BMD. The haplotype is within the region homologous to human chromosome 9p21, which has been implicated in several types of cancer. Conclusions We present the first GWAS for HS in any species. The data identify an associated haplotype in the highly cited tumor suppressor locus near CDKN2A. These data demonstrate the power of studying distinctive malignancies in highly predisposed dog breeds. Impact Here, we establish a naturally-occurring model of cancer susceptibility due to CDKN2 dysregulation, thus providing insight regarding this cancer-associated, complex, and poorly understood genomic region. PMID:22623710

Shearin, Abigail L.; Hedan, Benoit; Cadieu, Edouard; Erich, Suzanne A.; Schmidt, Emmett V.; Faden, Daniel L.; Cullen, John; Abadie, Jerome; Kwon, Erika M.; Gröne, Andrea; Devauchelle, Patrick; Rimbault, Maud; Karyadi, Danielle M.; Lynch, Mary; Galibert, Francis; Breen, Matthew; Rutteman, Gerard R.; André, Catherine; Parker, Heidi G.; Ostrander, Elaine A.

2012-01-01

197

In silico prediction of the cosmetic whitening effects of naturally occurring lead compounds.  

PubMed

The identification of tyrosinase inhibitors is important, not only for the treatment of skin hyperpigmentation disorders, such as melasma, but also for the production of cosmetic whitening effects. The aim of this study was the in silico prediction of the naturally occurring lead compounds in three commonly used skin-whitening herbs: Ampelopsis japonica, Lindera aggregata, and Ginkgo biloba. The active ingredients responsible for the whitening effect of these herbs remain largely unknown. The tyrosinase binding affinities and skin permeation, skin irritancy, and corrosive properties of43 natural constituents of the three herbs were predicted by docking simulations using Surflex-Dock and the QSAR-based Dermal Permeability Coefficient Program (DERMWIN) and Skin Irritation Corrosion Rules Estimation Tool (SICRET) implemented in Toxtree. Nine constituents of the three herbs were found to have more advanced binding energies than the gold standard whitening agents, arbutin and kojic acid, but 40 were indicative of at least one skin sensitization alert, and many exhibited poor skin permeability. Linderagalactone c and (+)-n-methyllaurotetanine were found to have the strongest prospects for use in topical formulations, as they achieved high predicted tyrosinase binding scores and displayed good skin permeation properties and minimal potential for skin sensitization and irritation. PMID:23156992

Fong, Pedro; Tong, Henry H Y

2012-10-01

198

In vitro Conversion of Vinyl to Formyl Groups in Naturally Occurring Chlorophylls  

PubMed Central

The chemical structural differences distinguishing chlorophylls in oxygenic photosynthetic organisms are either formyl substitution (chlorophyll b, d, and f) or the degree of unsaturation (8-vinyl chlorophyll a and b) of a side chain of the macrocycle compared with chlorophyll a. We conducted an investigation of the conversion of vinyl to formyl groups among naturally occurring chlorophylls. We demonstrated the in vitro oxidative cleavage of vinyl side groups to yield formyl groups through the aid of a thiol-containing compound in aqueous reaction mixture at room temperature. Heme is required as a catalyst in aqueous solution but is not required in methanolic reaction mixture. The conversion of vinyl- to formyl- groups is independent of their position on the macrocycle, as we observed oxidative cleavages of both 3-vinyl and 8-vinyl side chains to yield formyl groups. Three new chlorophyll derivatives were synthesised using 8-vinyl chlorophyll a as substrate: 8-vinyl chlorophyll d, [8-formyl]-chlorophyll a, and [3,8-diformyl]-chlorophyll a. The structural and spectral properties will provide a signature that may aid in identification of the novel chlorophyll derivatives in natural systems. The ease of conversion of vinyl- to formyl- in chlorophylls demonstrated here has implications regarding the biosynthetic mechanism of chlorophyll d in vivo. PMID:25119484

Loughlin, Patrick C.; Willows, Robert D.; Chen, Min

2014-01-01

199

Acoustic surface perception from naturally occurring step sounds of a dexterous hexapod robot  

NASA Astrophysics Data System (ADS)

Legged robots that exhibit dynamic dexterity naturally interact with the surface to generate complex acoustic signals carrying rich information on the surface as well as the robot platform itself. However, the nature of a legged robot, which is a complex, hybrid dynamic system, renders the more common approach of model-based system identification impractical. The present paper focuses on acoustic surface identification and proposes a non-model-based analysis and classification approach adopted from the speech processing literature. A novel feature set composed of spectral band energies augmented by their vector time derivatives and time-domain averaged zero crossing rate is proposed. Using a multi-dimensional vector classifier, these features carry enough information to accurately classify a range of commonly occurring indoor and outdoor surfaces without using of any mechanical system model. A comparative experimental study is carried out and classification performance and computational complexity are characterized. Different feature combinations, classifiers and changes in critical design parameters are investigated. A realistic and representative acoustic data set is collected with the robot moving at different speeds on a number of surfaces. The study demonstrates promising performance of this non-model-based approach, even in an acoustically uncontrolled environment. The approach also has good chance of performing in real-time.

Cuneyitoglu Ozkul, Mine; Saranli, Afsar; Yazicioglu, Yigit

2013-10-01

200

Synthetic molecular mimics of naturally occurring cyclopentenones exhibit antifungal activity towards pathogenic fungi.  

PubMed

The naturally occurring reactive electrophilic species 12-oxo-phytodienoic acid (12-oxo-PDA) is a potent antifungal agent, whereas the plant growth regulator jasmonic acid, which is synthesized from 12-oxo-PDA, is ineffective. To address what structural features of the molecule endow it with antifungal activity, we synthesized a series of molecular mimics of 12-oxo-PDA varying in the length of the alkyl chain at its C-4 ring position. The octyl analogue (4-octyl cyclopentenone) was the most effective at suppressing spore germination and subsequent mycelial growth of a range of fungal pathogens and was particularly effective against Cladosporium herbarum and Botrytis cinerea, with minimum fungicidal concentrations in the range 100-200 µM. Introduction of a carboxyl group to the end of the chain, mimicking natural fatty acids, markedly reduced antifungal efficacy. Electrolyte leakage, indicative of membrane perturbation, was evident in both C. herbarum and B. cinerea exposed to 4-octyl cyclopentenone. Lipid composition analysis of the fungal spores revealed that those species with a high oil content, namely Fusarium oxysporum and Alternaria brassicicola, were less sensitive to 4-octyl cyclopentenone. The comparable hydrophobicity of 4-octyl cyclopentenone and 12-oxo-PDA accounts for the similar spore suppression activity of these two compounds. The relative ease of synthesis of 4-octyl cyclopentenone makes it an attractive compound for potential use as an antifungal agent. PMID:21921102

Zhou, Yi; Behrendt, Jonathan; Sutherland, Andrew J; Griffiths, Gareth

2011-12-01

201

Identification of naturally occurring hybrids between two overexploited sciaenid species along the South African coast.  

PubMed

Hybridisation between fish species can play a significant role in evolutionary processes and can influence management and conservation planning, however, this phenomenon has been widely understudied, especially in marine organisms. The distribution limits of two sciaenid species (silver kob, Argyrosomus inodorus, and dusky kob, A. japonicus) partly overlap along the South African coast, where both species have undergone severe depletion due to overfishing. Following the identification of a number of possible cases of species misidentification or hybridisation (21 out of 422 individuals), nuclear and mitochondrial DNA data (12microsatellite loci and 562bp of the COI gene) were analysed to investigate the genetic composition of these individuals. Results indicated a field-based species misidentification rate of approximately 2.8% and a rate of natural hybridisation of 0.7%. Interestingly, all hybrid fish resulted from first-generation (F1) hybridisation events, which occurred exclusively between silver kob females and dusky kob males. Whether hybridisation is the result of natural events (such as secondary contact following a shift in distribution range), or anthropogenic activities (size-selective pressure due to overfishing), these findings have important implications for critical recovery and future management of these species in the wild. PMID:24582737

Mirimin, L; Kerwath, S E; Macey, B M; Bester-van der Merwe, A E; Lamberth, S J; Bloomer, P; Roodt-Wilding, R

2014-07-01

202

Bordetella pertussis naturally occurring isolates with altered lipooligosaccharide structure fail to fully mature human dendritic cells.  

PubMed

Bordetella pertussis is a Gram-negative bacterium and the causative agent of whooping cough. Despite high vaccination coverage, outbreaks are being increasingly reported worldwide. Possible explanations include adaptation of this pathogen, which may interfere with recognition by the innate immune system. Here, we describe innate immune recognition and responses to different B. pertussis clinical isolates. By using HEK-Blue cells transfected with different pattern recognition receptors, we found that 3 out of 19 clinical isolates failed to activate Toll-like receptor 4 (TLR4). These findings were confirmed by using the monocytic MM6 cell line. Although incubation with high concentrations of these 3 strains resulted in significant activation of the MM6 cells, it was found to occur mainly through interaction with TLR2 and not through TLR4. When using live bacteria, these 3 strains also failed to activate TLR4 on HEK-Blue cells, and activation of MM6 cells or human monocyte-derived dendritic cells was significantly lower than activation induced by the other 16 strains. Mass spectrum analysis of the lipid A moieties from these 3 strains indicated an altered structure of this molecule. Gene sequence analysis revealed mutations in genes involved in lipid A synthesis. Findings from this study indicate that B. pertussis isolates that do not activate TLR4 occur naturally and that this phenotype may give this bacterium an advantage in tempering the innate immune response and establishing infection. Knowledge on the strategies used by this pathogen in evading the host immune response is essential for the improvement of current vaccines or for the development of new ones. PMID:25348634

Brummelman, Jolanda; Veerman, Rosanne E; Hamstra, Hendrik Jan; Deuss, Anna J M; Schuijt, Tim J; Sloots, Arjen; Kuipers, Betsy; van Els, Cécile A C M; van der Ley, Peter; Mooi, Frits R; Han, Wanda G H; Pinelli, Elena

2015-01-01

203

Effects of Naturally Occurring Coumarins on Hepatic Drug Metabolizing Enzymes in Mice  

PubMed Central

Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme families involved in carcinogen metabolism. Generally, P450s play activation or detoxifying roles while GSTs act primarily as detoxifying enzymes. We previously demonstrated that oral administration of the linear furanocoumarins, isopimpinellin and imperatorin, modulated P450 and GST activities in various tissues of mice. The purpose of the present study was to compare a broader range of naturally occurring coumarins (simple coumarins, and furanocoumarins of the linear and angular type) for their abilities to modulate hepatic drug metabolizing enzymes when administered orally to mice. We now report that all of the different coumarins tested (coumarin, limettin, auraptene, angelicin, bergamottin, imperatorin and isopimpinellin) induced hepatic GST activities, whereas the linear furanocoumarins possessed the greatest abilities to induce hepatic P450 activities, in particular P450 2B and 3A. In both cases, this corresponded to an increase in protein expression of the enzymes. Induction of P4502B10, 3A11, and 2C9 by xenobiotics often are a result of activation of the pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Using a pregnane X receptor reporter system, our results demonstrated that isopimpinellin activated both PXR and its human ortholog SXR by recruiting coactivator SRC-1 in transfected cells. In CAR transfection assays, isopimpinellin counteracted the inhibitory effect of androstanol on full length mCAR, a Gal4-mCAR ligand binding domain fusion, and restored coactivator binding. Orally administered isopimpinellin induced hepatic mRNA expression of Cyp2b10,Cyp3a1, GSTa in CAR(+/+) wild-type mice. In contrast, the induction of Cyp2b10 mRNA by isopimpinellin was attenuated in the CAR(?/?) mice, suggesting that isopimpinellin induces Cyp2b10 via the CAR receptor. Overall, the current data indicate that naturally occurring coumarins have diverse activities in terms of inducing various xenobiotic metabolizing enzymes based on their chemical structure. PMID:18692084

Kleiner, Heather E.; Xia, Xiojun; Sonoda, Junichiro; Zhang, Jun; Pontius, Elizabeth; Abey, Jane; Evans, Ronald M.; Moore, David D.; DiGiovanni., John

2008-01-01

204

Effects of naturally occurring coumarins on hepatic drug-metabolizing enzymes inmice  

SciTech Connect

Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme families involved in carcinogen metabolism. Generally, P450s play activation or detoxifying roles while GSTs act primarily as detoxifying enzymes. We previously demonstrated that oral administration of the linear furanocoumarins, isopimpinellin and imperatorin, modulated P450 and GST activities in various tissues of mice. The purpose of the present study was to compare a broader range of naturally occurring coumarins (simple coumarins, and furanocoumarins of the linear and angular type) for their abilities to modulate hepatic drug-metabolizing enzymes when administered orally to mice. We now report that all of the different coumarins tested (coumarin, limettin, auraptene, angelicin, bergamottin, imperatorin and isopimpinellin) induced hepatic GST activities, whereas the linear furanocoumarins possessed the greatest abilities to induce hepatic P450 activities, in particular P450 2B and 3A. In both cases, this corresponded to an increase in protein expression of the enzymes. Induction of P4502B10, 3A11, and 2C9 by xenobiotics often is a result of activation of the pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Using a pregnane X receptor reporter system, our results demonstrated that isopimpinellin activated both PXR and its human ortholog SXR by recruiting coactivator SRC-1 in transfected cells. In CAR transfection assays, isopimpinellin counteracted the inhibitory effect of androstanol on full-length mCAR, a Gal4-mCAR ligand-binding domain fusion, and restored coactivator binding. Orally administered isopimpinellin induced hepatic mRNA expression of Cyp2b10, Cyp3a11, and GSTa in CAR(+/+) wild-type mice. In contrast, the induction of Cyp2b10 mRNA by isopimpinellin was attenuated in the CAR(-/-) mice, suggesting that isopimpinellin induces Cyp2b10 via the CAR receptor. Overall, the current data indicate that naturally occurring coumarins have diverse activities in terms of inducing various xenobiotic metabolizing enzymes based on their chemical structure.

Kleiner, Heather E. [Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Park Road 1-C, Smithville, TX 78957 (United States)], E-mail: hklein@lsuhsc.edu; Xia, Xiaojun; Sonoda, Junichiro [Howard Hughes Medical Institute, Gene Expression Laboratory, Salk Institute for Biological Sciences, La Jolla, CA 92037 (United States); Zhang, Jun [Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 (United States); Pontius, Elizabeth; Abey, Jane [Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Park Road 1-C, Smithville, TX 78957 (United States); Evans, Ronald M. [Howard Hughes Medical Institute, Gene Expression Laboratory, Salk Institute for Biological Sciences, La Jolla, CA 92037 (United States); Moore, David D. [Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 (United States); DiGiovanni, John [Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Park Road 1-C, Smithville, TX 78957 (United States)

2008-10-15

205

Infrared spectroscopic examination of the interaction of urea with the naturally occurring zeolite clinoptilolite  

USGS Publications Warehouse

Infrared spectroscopy has shown for the first time that the naturally occurring zeolite clinoptilolite can absorb urea, (NH2)2CO, under ambient conditions from either aqueous or ethanolic solutions. The two strongest NH stretching bands at 3441 and 3344 cm-1 in pure, solid urea shift to higher frequency (about 3504 and 3401 cm-1) after absorption. Two of the four urea bands in the 1800-1300 cm-1 range (at 1683 and 1467 cm-1) undergo marked downward shifts to about 1670 and 1445 cm-1. The other two bands show little change in frequency. The strong band at 1602 cm-1, however, diminishes in intensity to little more than an ill-defined shoulder on the 1626-cm-1 peak. When clinoptilolite is heated to 450 ??C and then treated with molten urea (ca. 140 ??C) for several minutes, and finally washed twice with ethanol to remove excess unreacted urea, further changes become apparent in the spectrum of the urea-treated clinoptilolite. The two NH stretching bands broaden without significant change in frequency. Two new bands appear in the midfrequency range at 1777 (weak) and 1719 (medium strong) cm-1. Of the four original midfrequency peaks, the one at 1602 cm-1 is now absent. Two others (1627 and 1440 cm-1) exhibit little change, while the fourth has broadened and shifted down to 1663 cm-1, where it appears as a shoulder on the band at 1627 cm-1. Both treatments clearly induce interaction between urea and the zeolite which seems to result in significant modifications in the nature of the hydrogen bonding of the substrate. ?? 1991.

Byler, D.M.; Gerasimowicz, W.V.; Stockette, V.M.; Eberl, D.D.

1991-01-01

206

Pennsylvania's technologically enhanced, naturally occurring radioactive material experiences and studies of the oil and gas industry.  

PubMed

This presentation provides an overview of the Commonwealth of Pennsylvania's experiences and ongoing studies related to technologically enhanced, naturally occurring radioactive material (TENORM) in the oil and gas industry. It has been known for many years that Pennsylvania's geology is unique, with several areas having relatively high levels of natural uranium and thorium. In the 1950s, a few areas of the state were evaluated for commercial uranium production. In the late 1970s, scoping studies of radon in homes prompted the Pennsylvania Department of Environmental Protection (DEP) Bureau of Radiation Protection (BRP) to begin planning for a larger state-wide radon study. The BRP and Oil and Gas Bureau also performed a TENORM study of produced water in the early 1990s for a number of conventional oil and gas wells. More recently, BRP and the Bureau of Solid Waste developed radiation monitoring regulations for all Pennsylvania solid waste disposal facilities. These were implemented in 2001, prompting another evaluation of oil and gas operations and sludge generated from the treatment of conventionally produced water and brine but mainly focused on the disposal of TENORM solid waste in the state's Resource Conservation and Recovery Act Subtitle D landfills. However, since 2008, the increase in volumes of gas well wastewater and levels of Ra observed in the unconventional shale gas well flow-back fracking water has compelled DEP to fully re-examine these oil and gas operations. Specifically, with BRP in the lead, a new TENORM study of oil and gas operations and related wastewater treatment operations has been initiated (), supported by an American National Standards Institute standard on TENORM () and a U.S. Government Accountability Office report on shale resource development and risks (). This study began in early 2013 and will examine the potential public and worker radiation exposure and environmental impact as well as re-evaluate TENORM waste disposal. This presentation summarizes conventional and unconventional oil and gas well operations, geology and respective uranium/thorium content, radium content in oil and gas wastewater, treatment solids, radon in natural gas, the scope of other TENORM issues in the state, regulatory framework, national regulations and guidance. It also provides an overview of past and the status of ongoing TENORM studies in the Commonwealth (; Rowan and Kraemer 2012; ). PMID:25551500

Allard, David J

2015-02-01

207

Effect of naturally occurring apatites on growth and morphology of algae.  

PubMed

Crystals (30--100 micrometer) of selected naturally occurring apatite (Ca10 (PO4)6(OH, F)2) samples were added to P-free (less than 0.001 microgram/ml total P) Bristol's medium (1-1000 microgram/ml of apatite) as the sole source of ortho-PO43-. The media were inoculated with washed, non-axenic cells of three chlorophycean algal species cultivated under PO43--deficient conditions. Phase-contrast and scanning electron microscopy revealed that at low slurry densities (1-10 microgram/ml of apatite), Ankistrodesmus braunii (ATCC 2744) cells were morphologically distorted. At concentrations of 100 and 1000 microgram/ml of apatite, more than 85% of the cells had undergone autospore formation within 7--10 days of incubation at 20 degrees C. Most autospores formed failed to germinate under high nutrient conditions. Scenedesmus longus (No. 1236) formed colonies when cultivated in Bristol's medium but daughter cells displayed a Chodatella-like unicellular morphology when grown in apatite media. Test algal species (Chlamydomonas dysosmos, S. longus, A. braunii) showed a marked preference for growth on apatite crystals over non-nutritive surfaces. Unialgal and mixed-algal cultures produced an extensive matrix of extracellular fibrous material in response to growth on crystals at concentrations greater than 10 microgram/ml of apatite. PMID:907915

Smith, E A; Mayfield, C I; Wong, P T; Silverberg, B A

1977-09-01

208

Contact Mechanics of Naturally Occurring Grains: Experiments and Discrete Element Modeling  

NASA Astrophysics Data System (ADS)

Application of the discrete element method to engineering problems involving naturally occurring granular materials requires knowledge of the contact mechanics of the particles and a realistic treatment of particle shapes. This paper presents results from on-going work that addresses these two fundamental issues of granular media mechanics. Grain-scale laboratory experiments are being conducted to provide the needed contact relationships. A concurrent discrete element modeling effort is under way to implement the experimentally determined contact relationships and employ realistic particle shapes. The experiments determine the stiffness and frictional behavior of normal and sliding contacts of observed for spherical specimens of gneiss. Stiffness in the normal mode is seen to range from 0.1 to 15 MN m-1 depending on force level. Shear stiffness is on the order of the normal stiffness, but only for relatively low shear force levels (or shear deformations). Frictional energy losses are observed to varying degrees under virtually all experimental conditions. The discrete element modeling effort simulates the triaxial response of the spherical grains enclosed in a membrane and implements the experimentally determined contact relationships for normal and sliding contact behavior. Inclusion of the full frictional behavior prior to macroscopic sliding is under development. Some aspects of the simulations of the triaxial deformation of spherical grains of gneiss are presented and compared with the grain-scale experimental data. The simulations are seen to capture the key features of the experimental observations.

Cole, David M.; Hopkins, Mark A.

2009-06-01

209

Microbial Utilization of Naturally Occurring Hydrocarbons at the Guaymas Basin Hydrothermal Vent Site †  

PubMed Central

The Guaymas Basin (Gulf of California; depth, 2,000 m) is a site of hydrothermal activity in which petroliferous material is formed by thermal alteration of deposited planktonic and terrestrial organic matter. We investigated certain components of these naturally occurring hydrocarbons as potential carbon sources for a specific microflora at these deep-sea vent sites. Respiratory conversion of [1-14C]hexadecane and [1(4,5,8)-14C]naphthalene to 14CO2 was observed at 4°C and 25°C, and some was observed at 55°C, but none was observed at 80°C. Bacterial isolates were capable of growing on both substrates as the sole carbon source. All isolates were aerobic and mesophilic with respect to growth on hydrocarbons but also grew at low temperatures (4 to 5°C). These results correlate well with previous geochemical analyses, indicating microbial hydrocarbon degradation, and show that at least some of the thermally produced hydrocarbons at Guaymas Basin are significant carbon sources to vent microbiota. PMID:16348045

Bazylinski, Dennis A.; Wirsen, Carl O.; Jannasch, Holger W.

1989-01-01

210

Two Naturally Occurring Terpenes, Dehydrocostuslactone and Costunolide, Decrease Intracellular GSH Content and Inhibit STAT3 Activation  

PubMed Central

The main purpose of the present study is to envisage the molecular mechanism of inhibitory action ofdehydrocostuslactone (DCE) andcostunolide (CS), two naturally occurring sesquiterpene lactones, towards the activation of signal transducer and activator of transcription 3 (STAT3). We report that, in human THP-1 cell line, they inhibit IL-6-elicited tyrosine phosphorylation of STAT3 and its DNA binding activity with EC50 of 10 µM with concomitantdown-regulation ofthe phosphorylation of the tyrosine Janus kinases JAK1, JAK2 and Tyk2. Furthermore, these compounds that contain an ?-?-unsatured carbonyl moiety and function as potent Michael reaction acceptor, induce a rapid drop in intracellular glutathione (GSH) concentration by direct interaction with it, thereby triggering S-glutathionylation of STAT3. Dehydrocostunolide (HCS), the reduced form of CS lacking only the ?-?-unsaturated carbonyl group, fails to exert any inhibitory action. Finally, the glutathione ethylene ester (GEE), the cell permeable GSH form, reverts the inhibitory action of DCE and CS on STAT3 tyrosine phosphorylation. We conclude that these two sesquiterpene lactones are able to induce redox-dependent post-translational modification of cysteine residues of STAT3 protein in order to regulate its function. PMID:21625597

Butturini, Elena; Cavalieri, Elisabetta; Carcereri de Prati, Alessandra; Darra, Elena; Rigo, Antonella; Shoji, Kazuo; Murayama, Norie; Yamazaki, Hiroshi; Watanabe, Yasuo; Suzuki, Hisanori; Mariotto, Sofia

2011-01-01

211

Using naturally occurring polysaccharides to align molecules with nonlinear optical activity  

NASA Technical Reports Server (NTRS)

The Biophysics and Advanced Materials Branch of the Microgravity Science and Applications Division at Marshall Space Flight Center has been investigating polymers with the potential for nonlinear optical (NLO) applications for a number of years. Some of the potential applications for NLO materials include optical communications, computing, and switching. To this point the branch's research has involved polydiacetylenes, phthalocyanins, and other synthetic polymers which have inherent NLO properties. The aim of the present research is to investigate the possibility of using naturally occurring polymers such as polysaccharides or proteins to trap and align small organic molecules with useful NLO properties. Ordering molecules with NLO properties enhances 3rd order nonlinear effects and is required for 2nd order nonlinear effects. Potential advantages of such a system are the flexibility to use different small molecules with varying chemical and optical properties, the stability and cost of the polymers, and the ability to form thin, optically transparent films. Since the quality of any polymer films depends on optimizing ordering and minimizing defects, this work is particularly well suited for microgravity experiments. Polysaccharide and protein polymers form microscopic crystallites which must align to form ordered arrays. The ordered association of crystallites is disrupted by gravity effects and NASA research on protein crystal growth has demonstrated that low gravity conditions can improve crystal quality.

Prasthofer, Thomas

1996-01-01

212

Repair of naturally occurring mismatches can induce mutations in flanking DNA  

PubMed Central

‘Normal’ genomic DNA contains hundreds of mismatches that are generated daily by the spontaneous deamination of C (U/G) and methyl-C (T/G). Thus, a mutagenic effect of their repair could constitute a serious genetic burden. We show here that while mismatches introduced into human cells on an SV40-based episome were invariably repaired, this process induced mutations in flanking DNA at a significantly higher rate than no mismatch controls. Most mutations involved the C of TpC, the substrate of some single strand-specific APOBEC cytidine deaminases, similar to the mutations that can typify the ‘mutator phenotype’ of numerous tumors. siRNA knockdowns and chromatin immunoprecipitation showed that TpC preferring APOBECs mediate the mutagenesis, and siRNA knockdowns showed that both the base excision and mismatch repair pathways are involved. That naturally occurring mispairs can be converted to mutators, represents an heretofore unsuspected source of genetic changes that could underlie disease, aging, and evolutionary change. DOI: http://dx.doi.org/10.7554/eLife.02001.001 PMID:24843013

Chen, Jia; Miller, Brendan F; Furano, Anthony V

2014-01-01

213

Radiological dose assessment related to management of naturally occurring radioactive materials generated by the petroleum industry  

SciTech Connect

A preliminary radiological dose assessment of equipment decontamination, subsurface disposal, landspreading, equipment smelting, and equipment burial was conducted to address concerns regarding the presence of naturally occurring radioactive materials (NORM) in production waste streams. The assessment estimated maximum individual dose equivalents for workers and the general public. Sensitivity analyses of certain input parameters also were conducted. On the basis of this assessment, it is concluded that (1) regulations requiring workers to wear respiratory protection during equipment cleaning operations are likely to result in lower worker doses, (2) underground injection and downhole encapsulation of NORM wastes present a negligible risk to the general public, and (3) potential doses to workers and the general public related to smelting NORM-contaminated equipment can be controlled by limiting the contamination level of the initial feed. It is recommended that (1) NORM wastes be further characterized to improve studies of potential radiological doses; (2) states be encouraged to permit subsurface disposal of NORM more readily, provided further assessments support this study; results; (3) further assessment of landspreading NORM wastes be conducted; and (4) the political, economic, sociological, and nonradiological issues related to smelting NORM-contaminated equipment be studied to fully examine the feasibility of this disposal option.

Smith, K.P.; Blunt, D.L.; Williams, G.P. [Argonne National Lab., IL (United States). Environmental Assessment Div.; Tebes, C.L. [Univ. of Illinois, Urbana, IL (United States)

1996-09-01

214

Antioxidant effect of naturally occurring xanthines on the oxidative damage of DNA bases  

NASA Astrophysics Data System (ADS)

The repair of the oxidised radicals of adenine and guanosine by several naturally occurring xanthines was studied. Each pair of DNA purine/xanthine was made to react with the sulphate radical and the decrease of the concentration of both compounds was measured by HPLC as a function of irradiation time. The results show that xanthine efficiently prevents the oxidation of the two DNA purines. Theophyline and paraxanthine repair the oxidised radical of adenine but not the one from guanosine. Theobromine and caffeine do not show any protecting effect. An order of the oxidation potentials of all the purines studied is proposed. La réparation des radicaux oxydés de l'adénine et de la guanosine par des xanthines naturelles a été étudiée en soumettant chaque paire base de l'ADN/xanthine à l'oxydation par le radical sulfate et en mesurant par HPLC la disparition des deux composés en fonction du temps d'irradiation. Les résultats montrent que la xanthine joue un rôle protecteur efficace contre l'oxydation des deux purines de l'ADN. La théophyline et la paraxanthine réparent le radical oxydé de l'adénine mais pas celui de la guanosine. La théobromine et la cafeíne n'ont pas d'effet protecteur. Un ordre de potentiels d'oxydation des purines étudiées est proposé.

Vieira, A. J. S. C.; Telo, J. P.; Pereira, H. F.; Patrocínio, P. F.; Dias, R. M. B.

1999-01-01

215

An overview of naturally occurring radioactive materials (NORM) in the petroleum industry  

SciTech Connect

Oil and gas extraction and processing operations sometimes accumulate naturally occurring radioactive materials (NORM) at concentrations above normal in by-product waste streams. Results from NORM surveys indicate that radionuclide concentrations can be quite variable, ranging from undetectable to extremely high levels. To date, efforts to characterize the geographic distribution of NORM have been limited by poor statistical representation. In addition, the fate of NORM in the environment has not been fully defined, and few human health risk assessment have been conducted. Both the petroleum industry and regulators are becoming increasingly concerned about the presence of NORM. At present, most existing federal environmental regulations do not address oil and gas NORM, and only a few states have developed regulatory programs. Available data suggest that the occurrence of NORM (and associated health risks) is significant enough to warrant increased regulatory control. However, before these regulations can be developed, additional research is needed to (1) better characterize the occurrence and distribution of NORM throughout the industry, (2) quantify hazards posed by NORM to industry workers and the general public, and (3) develop effective waste treatment and minimization technologies that will lower the risk associated with NORM and reduce disposal costs.

Smith, K.P.

1992-12-01

216

Investigation of the activity level and radiological impacts of naturally occurring radionuclides in blast furnace slag.  

PubMed

The activity level and possible radiological impacts of naturally occurring radionuclides on the health of workers and members of the public, as a result of utilisation of blast furnace slag (BFS) samples as a substitute for aggregate in road construction were investigated by using a gamma-ray spectrometer and potential exposure scenarios given in Radiation Protection 122. The mean activity concentrations of the (226)Ra, (232)Th and (40)K in BFS samples were found to be 152.4, 54.9 and 183.1 Bq kg(-1), respectively. These values are compared with typical values measured in BFS samples from the European Union countries, which are 270, 70 and 240 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The values of radium equivalent activity index calculated for BFS samples were within the recommended safety limits. The highest total annual effective doses evaluated as 0.9 and 0.4 mSv y(-1) for members of the public and workers, respectively, were lower than the annual limit of 1 mSv y(-1). PMID:22826355

U?ur, F A; Turhan, S; Sahan, H; Sahan, M; Gören, E; Gezer, F; Ye?ingil, Z

2013-01-01

217

Studies of two naturally occurring compounds which effect release of acetylcholine from synaptosomes. [Leptinotarsa decemlineata  

SciTech Connect

Two naturally occurring compounds which effect the release of neurotransmitter from synaptosomes have been purified to apparent homogeneity. Iotrochotin (IOT) isolated from wound exudate of the Caribbean purple bleeder sponge promotes release in a manner that is independent of the extracellular Ca/sup 2 +/ ion concentration. Leptinotarsin (LPT-d), a protein taken from hemolymph of the Colorado potato beetle, Leptinotarsa decemlineata, stimulates Ca/sup 2 +/-dependent release. IOT is slightly acidic and has a molecular weight of approximately 18 kD. (/sup 3/H)acetylcholine which has been introduced into synaptosomes as (/sup 3/H)choline can be released by IOT. The toxin releasable pool of labelled neurotransmitter is not depleted by depolarization of the synaptosomes with high potassium, and therefore seems to be primarily extravesicular. LPT-d is a larger protein (molecular weight = 45 kD) than IOT, and seems to effect primarily vesicular release by opening at least one type of presynaptic Ca/sup 2 +/ channel. The facilitatory effects of the toxin on synaptosomal release can be inhibited by inorganic Ca/sup 2 +/ channel antagonists, but are not generally affected by organic antagonists.

Koenig, M.L.

1985-01-01

218

Recombinant Moraxella bovoculi cytotoxin-ISCOM matrix adjuvanted vaccine to prevent naturally occurring infectious bovine keratoconjunctivitis  

PubMed Central

A randomized, blinded, controlled field trial was conducted during summer 2006 in a northern California, USA, herd of beef cattle to evaluate the efficacy of a recombinant Moraxella bovoculi cytotoxin subunit vaccine to prevent naturally occurring infectious bovine keratoconjunctivitis (IBK; pinkeye). A convenience sample comprised of 127 steers were administered a subcutaneous dose of either adjuvant alone (ISCOM matrices; control group) or recombinant M. bovoculi cytotoxin carboxy terminus adjuvanted with ISCOM matrices (MbvA group) and were boostered 21 days later. The steers were examined once weekly for 15 weeks for evidence of IBK. No significant difference in the cumulative proportion of corneal ulcerations was detected between groups. Compared to the control calves, the MbvA vaccinates had significantly higher increases in serum neutralizing titers to M. bovoculi hemolysin between week 0 and week 6. The prevalence of M. bovis isolations was higher from ulcerated eyes of calves vaccinated with MbvA as compared to control calves. Vaccination of calves against the carboxy terminus of M. bovoculi RTX toxin resulted in significant increases in serum hemolysin neutralizing titers and may modulate organism type cultured from ulcerated eyes of calves in herds where both M. bovis and M. bovoculi exist. Use of M. bovoculi antigens alone in vaccines to prevent IBK may not be beneficial in herds where IBK is associated with both M. bovoculi and M. bovis. PMID:20217228

Lane, V. Michael; Ball, Louise M.; Hess, John F.

2010-01-01

219

Antigens of Tumours Induced by Naturally Occurring Murine Sarcoma Virus (MSV-FBJ)  

PubMed Central

Antigens associated with cells transformed in vivo by FBJ virus, a wild type murine sarcoma virus (MSV) complex originating from a spontaneously arising osteosarcoma in a CF1 mouse, have been partially characterized by complement fixation (CF). Using rat antisera against antigens specified by Gross leukaemia virus (GLV) the group specific (gs) antigen of C-type RNA murine tumour viruses was demonstrated in FBJ tumours as well as in GLV rat leukaemias, AKR lymphomata and sarcomata induced by MSV-H (Harvey), an MSV isolate of Friend-Moloney-Rauscher (FMR) subgroup specificity. Using mouse antisera against antigens present in FBJ cells the Gross (G) or wild type specificity of FBJ tumours was demonstrated by cross reactivity with antigens expressed on normal AKR lymphoid tissues and leukaemias. These antigens were absent from MSV-H induced sarcomata and in reciprocal tests mouse antisera to MSV-H failed to react with antigens present in FBJ tumour cells. No distinction between cellular and virion antigens expressed by FBJ cells was possible by CF although evidence for a cellular antigen with G specificity was obtained in tests using aged C57B1 antiserum containing a naturally occurring G antibody lacking significant virus neutralizing capacity. However, the likelihood that mouse FBJ antisera contain antibodies to type specific viral envelope antigens (VEA) as well as cellular antigen is discussed. PMID:4820943

Jones, D. B.; Moore, M.

1974-01-01

220

Evaluation of naturally occurring radioactive materials (NORM) in the South Western oil wells of Iran.  

PubMed

An investigation was carried out to find out the concentration of Naturally Occurring Radioactive Materials (NORMs) in an oil production unit, an evaporation pond, and a drilling site in the Khuzestan province, in south west Iran the 4th largest oil producing country in the world. The nuclides (232)Th and (40)K were determined in soil samples and (226)Ra was analyzed in both soil and water. The (232)Th ranged between 8.7 and 403 Bq kg(-1), while the minimum concentration for (40)K was much larger, i.e. 82 Bq kg(-1) and its maximum concentration was 815 Bq kg(-1). Soil samples indicated very low concentrations of (226)Ra, typically between 10.6 and 42.1 Bq kg(-1) with some exceptions of 282, 602, and even 1480 Bq kg(-1). Also, the range for (226)Ra in water was less from 0.1 to a maximum 30.3 Bq L(-1). Results show that on average, NORM concentrations in these areas are lower in comparison with the usual concentration levels in typical oil and gas fields, but despite this fact, necessary measures have to be taken in order to minimize the environmental impact of radioactive materials. PMID:22321893

Khodashenas, Alireza; Roayaei, Emad; Abtahi, Seyed Mojtaba; Ardalani, Elham

2012-07-01

221

SUPPLEMENTARY COMPARISON Technically enhanced naturally occurring radionuclides (TENORM) in phosphogypsum: Comparison CCRI(II)-S5  

NASA Astrophysics Data System (ADS)

Within the frame of mutual cooperation between the IAEA and the BIPM, the Consultative Committee for Ionizing Radiation Section II—Measurement of Radionuclides accepted an IAEA-organized interlaboratory comparison in 2008 on the determination of technically enhanced naturally occurring radionuclides in phosphogypsum. The study was piloted by the Chemistry Unit at the IAEA's Laboratories in Seibersdorf (Austria). This report presents the methodology applied in conducting this comparison and the results. Activity results for Pb-210, Ra-226, Th-230, U-234, U-235 and U-238 were reported by three national metrology institutes (NMI) and five other expert laboratories or designated institutes. Four different approaches were used to calculate the nominal value of the reported results and associated uncertainties, and the results from each individual participant were evaluated and compared with this nominal reference value. The reported evaluation of the measurement results demonstrated agreement amongst the participating laboratories. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section II, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Shakhashiro, A.; Sansone, U.; Wershofen, H.; Bollhöfer, A.; Kim, C. K.; Kim, C. S.; Korun, M.; Moune, M.; Lee, S. H.; Tarjan, S.

2010-01-01

222

Microbial utilization of naturally occurring hydrocarbons at the Guaymas Basin hydrothermal vent site  

SciTech Connect

The Guaymas Basin (Gulf of California; depth, 2,000 m) is a site of hydrothermal activity in which petroliferous materials is formed by thermal alteration of deposited planktonic and terrestrial organic matter. We investigated certain components of these naturally occurring hydrocarbons as potential carbon sources for a specific microflora at these deep-sea vent sites. Respiratory conversion of (1-{sup 14}C)hexadecane and (1(4,5,8)-{sup 14}C)naphthalene to {sup 14}CO{sub 2} was observed at 4{degree}C and 25{degree}C, and some was observed at 55{degree}C, but none was observed at 80{degree}C. Bacterial isolates were capable of growing on both substrates as the sole carbon source. All isolates were aerobic and mesophilic with respect to growth on hydrocarbons but also grew at low temperatures (4 to 5{degree}C). These results correlate well with previous geochemical analyses, indicating microbial hydrocarbon degradation, and show that at least some of the thermally produced hydrocarbons at Guaymas Basin are significant carbon sources to vent microbiota.

Bazylinski, D.A.; Wirsen, C.O.; Jannasch, H.W. (Woods Hole Oceanographic Institution, MA (USA))

1989-11-01

223

Effects of conserved residues and naturally occurring mutations on Mycobacterium tuberculosis RecG helicase activity  

PubMed Central

RecG is a helicase that is conserved in nearly all bacterial species. The prototypical Escherichia coli RecG promotes regression of stalled replication forks, participates in DNA recombination and DNA repair, and prevents aberrant replication. Mycobacterium tuberculosis RecG (RecGMtb) is a DNA-dependent ATPase that unwinds a variety of DNA substrates, although its preferred substrate is a Holliday junction. Here, we performed site-directed mutagenesis of selected residues in the wedge domain and motifs Q, I, Ib and VI of RecGMtb. Three of the 10 substitution mutations engineered were detected previously as naturally occurring SNPs in the gene encoding RecGMtb. Alanine substitution mutations at residues Q292, F286, K321 and R627 abolished the RecGMtb unwinding activity, whilst RecGMtb F99A, P285S and T408A mutants exhibited ~25–50?% lower unwinding activity than WT. We also found that RecGMtb bound ATP in the absence of a DNA cofactor. PMID:24169816

Zegeye, Ephrem Debebe; Balasingham, Seetha V.; Laerdahl, Jon K.; Homberset, Håvard; Kristiansen, Per E.

2014-01-01

224

Larvicidal activity of naturally occurring naphthalenedione and its structurally related analogs against three mosquito species.  

PubMed

The objective of this study was to determine the larvicidal activity of an active compound isolated from Cercis chinensis heartwood and its structurally related analogs against 4th-stage Aedes aegypti, Culex pipiens pallens, and Ae. togoi. The larvicidal compound of C. chinensis was isolated with the use of various chromatographic techniques and identified as analogs of 1,4-naphthalenedione. Based on the median lethal concentration (LC50) values of commercially procured analogs against Ae. aegypti larvae, the most toxic analog was 2-bromo-1,4-naphthalenedione (1.19 µg/ml); followed by 5-hydroxy-1,4-naphthalenedione (1.72 µg/ml); 2-methyl-1,4-naphthalenedione (9.12 µg/ml); 2-hydroxy-1,4-naphthalenedione (10.76 µg/ml); and 2-methoxy-1,4-naphthalenedione (12.50 µg/ml). Similar results were observed against Cx. p. pallens and Ae. togoi larvae with 1,4-naphthalenedione analogs. These results also showed that 1,4-naphthalenedione analogs were less toxic than the organophosphate pirimiphos-methyl. Nonetheless, naturally occurring C. chinensis-derived materials and 1,4-naphthalenedione analogs have potential for development as mosquito larvicidal agents. PMID:25843178

Jeon, Ju-Hyun; Kim, Min-Gi; Lee, Hoi-Seon

2015-03-01

225

The phytoestrogen coumestrol is a naturally occurring antagonist of the human pregnane X receptor.  

PubMed

Antagonizing the action of the human nuclear xenobiotic receptor pregnane X receptor (PXR) may have important clinical implications in preventing drug-drug interactions and improving therapeutic efficacy. We provide evidence that a naturally occurring phytoestrogen, coumestrol, is an antagonist of the nuclear receptor PXR (NR1I2). In transient transfection assays, coumestrol was able to suppress the agonist effects of SR12813 on human PXR activity. PXR activity was assessed and correlated with effects on the metabolism of the anesthetic tribromoethanol and on gene expression in primary human hepatocytes. We found that coumestrol was able to suppress the effects of PXR agonists on the expression of the known PXR target genes, CYP3A4 and CYP2B6, in primary human hepatocytes as well as inhibit metabolism of tribromoethanol in humanized PXR mice. Coumestrol at concentrations above 1.0 microm competed in scintillation proximity assays with a labeled PXR agonist for binding to the ligand-binding cavity. However, mammalian two-hybrid assays and transient transcription data using ligand-binding-cavity mutant forms of PXR show that coumestrol also antagonizes coregulator recruitment. This effect is likely by binding to a surface outside the ligand-binding pocket. Taken together, these data imply that there are antagonist binding site(s) for coumestrol on the surface of PXR. These studies provide the basis for development of novel small molecule inhibitors of PXR with the ultimate goal of clinical applications toward preventing drug-drug interactions. PMID:18096694

Wang, Hongwei; Li, Hao; Moore, Linda B; Johnson, Michael D L; Maglich, Jodi M; Goodwin, Bryan; Ittoop, Olivia R R; Wisely, Bruce; Creech, Katrina; Parks, Derek J; Collins, Jon L; Willson, Timothy M; Kalpana, Ganjam V; Venkatesh, Madhukumar; Xie, Wen; Cho, Sool Y; Roboz, John; Redinbo, Matthew; Moore, John T; Mani, Sridhar

2008-04-01

226

Phenomenon of Coolant Local Natural Circulation Occurring in Heat Removal Loops of Nuclear Power Plant  

Microsoft Academic Search

The paper presents the results of experimental research performed at the BN-350 NPP, which have allowed the identification of a local natural circulation phenomenon arising in some sections of the NPP heat removal loops. The nature of this phenomenon and the features of its interaction with a total-circuit natural circulation are described. Also, the possible influence of the local natural

Yury ASHURKO; Gennady PUGACHEV

2011-01-01

227

Acute Toxicological Responses of Fischer Rats to Naturally Occurring Asbestos from theUnited States and Canada  

EPA Science Inventory

This study was designed to provide understanding of the toxicity of naturally occurring asbestos (NOA) including Libby amphibole (LA), Sumas Mountain chrysotile (SM), EI Dorado Hills tremolite (ED) and Ontario actinolite/ferroactinolite cleavage fragments (ON). Ratrespirable fra...

228

Managing for Successful Control of Naturally Occurring Asbestos During Large Scale Grading  

NASA Astrophysics Data System (ADS)

Pacific Gas and Electric Company recently completed environmental remediation and civil grading of a 35-acre site in San Francisco Bay Area, and the project became recognized with local agencies as having excellent controls systems for naturally-occurring asbestos (NOA). The project began in 2010 and was completed in 2012, and involved excavating and grading over 100,000 tons of soil containing NOA. The work was subject to requirements by state, local and regional agencies, including an asbestos dust mitigation plan for the Bay Area Air Quality Management District. Effective control of NOA is attributed to management approaches combined with effective monitoring and state-of-the-art controls. Management Planning. The contract for construction specified NOA compliance management and controls, including having a NOA-control "czar" ultimately responsible for effective mitigation. An important element was daily pre-planning for excavation/grading that involved both the NOA mitigation experts and construction staff. Personnel Planning and Training. All construction personnel were trained before work regarding NOA hazards and mitigations. Daily tailboards with all construction personnel included discussions of the NOA controls integral to the daily work. Supervision. A NOA mitigation compliance leader was assigned to each excavation operation, responsible for continuously monitoring wind direction and work to ensure mitigation met requirements, and that disturbed areas were hydrosealed or covered. Adaptive Management - Daily and weekly debriefs occurred with those responsible for NOA controls to evaluate effectiveness, and identify improvements needed. If a monitoring result exceeded the project trigger level, work shut down and a root-cause analysis was performed to determine appropriate corrective actions. Deviations of results from background were researched as to cause, and any adjustments identified. Nearby non-project activities were monitored, as they occasionally caused trigger level exceedences in perimeter monitors, including from off-site vehicles, nearby construction, and mechanical vegetation management (e.g. weed whacking). Regulatory and Owner Oversight. Monitoring results were reported daily to agencies, agencies made frequent inspections, and owner's independent compliance representatives observed the NOA mitigation and provided real-time feedback to the construction team. NOA Controls. NOA emissions were controlled site-wide and for each work activity. Site systems included misting, water trucks on roads, temporary covers and soil sealants. Work activity controls for excavation/grading included both source and perimeter controls. Water application technologies specially designed for NOA fiber mitigation, and not just dust mitigation, were effective without adding excessive water to work areas. These activities collectively created a management structure that facilitated successful implementation of NOA control technologies.

Saur, R.; Harnish, D.; Cavanaugh, J.; Kendall, K.; Virdee, A.; Ludlam, D.

2012-12-01

229

Antibacterial activities of naturally occurring compounds against Mycobacterium avium subsp. paratuberculosis.  

PubMed

The antibacterial activities of 18 naturally occurring compounds (including essential oils and some of their isolated constituents, apple and green tea polyphenols, and other plant extracts) against three strains of Mycobacterium avium subsp. paratuberculosis (a bovine isolate [NCTC 8578], a raw-milk isolate [806R], and a human isolate [ATCC 43015]) were evaluated using a macrobroth susceptibility testing method. M. avium subsp. paratuberculosis was grown in 4 ml Middlebrook 7H9 broth containing 10% oleic acid-albumin-dextrose-catalase, 0.05% Tween 80 (or 0.2% glycerol), and 2 microg/ml mycobactin J supplemented with five concentrations of each test compound. The changes in the optical densities of the cultures at 600 nm as a measure of CFU were recorded at intervals over an incubation period of 42 days at 37 degrees C. Six of the compounds were found to inhibit the growth of M. avium subsp. paratuberculosis. The most effective compound was trans-cinnamaldehyde, with a MIC of 25.9 microg/ml, followed by cinnamon oil (26.2 microg/ml), oregano oil (68.2 microg/ml), carvacrol (72.2 microg/ml), 2,5-dihydroxybenzaldehyde (74 microg/ml), and 2-hydroxy-5-methoxybenzaldehyde (90.4 microg/ml). With the exception of carvacrol, a phenolic compound, three of the four most active compounds are aldehydes, suggesting that the structure of the phenolic group or the aldehyde group may be important to the antibacterial activity. No difference in compound activity was observed between the three M. avium subsp. paratuberculosis strains studied. Possible mechanisms of the antimicrobial effects are discussed. PMID:18676709

Wong, Stella Y Y; Grant, Irene R; Friedman, Mendel; Elliott, Christopher T; Situ, Chen

2008-10-01

230

HIV Infection of Naturally Occurring and Genetically Reprogrammed Human Regulatory T-cells  

PubMed Central

A T-cell subset, defined as CD4+CD25hi (regulatory T-cells [Treg cells]), was recently shown to suppress T-cell activation. We demonstrate that human Treg cells isolated from healthy donors express the HIV-coreceptor CCR5 and are highly susceptible to HIV infection and replication. Because Treg cells are present in very few numbers and are difficult to expand in vitro, we genetically modified conventional human T-cells to generate Treg cells in vitro by ectopic expression of FoxP3, a transcription factor associated with reprogramming T-cells into a Treg subset. Overexpression of FoxP3 in naïve human CD4+ T-cells recapitulated the hyporesponsiveness and suppressive function of naturally occurring Treg cells. However, FoxP3 was less efficient in reprogramming memory T-cell subset into regulatory cells. In addition, FoxP3-transduced T-cells also became more susceptible to HIV infection. Remarkably, a portion of HIV-positive individuals with a low percentage of CD4+ and higher levels of activated T-cells have greatly reduced levels of FoxP3+CD4+CD25hi T-cells, suggesting disruption of the Treg cells during HIV infection. Targeting and disruption of the T-cell regulatory system by HIV may contribute to hyperactivation of conventional T-cells, a characteristic of HIV disease progression. Moreover, the ability to reprogram human T-cells into Treg cells in vitro will greatly aid in decoding their mechanism of suppression, their enhanced susceptibility to HIV infection, and the unique markers expressed by this subset. PMID:15252446

Oswald-Richter, Kyra; Grill, Stacy M; Shariat, Nikki; Leelawong, Mindy; Sundrud, Mark S; Haas, David W

2004-01-01

231

Biochemical changes in the jejunal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency.  

PubMed

The roles of extracellular and intracellular mechanisms in the degradation of brush border proteins have been investigated by studying the small intestinal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency. Peroral jejunal biopsies were homogenised and the organelles separated by isopycnic centrifugation on continuous sucrose density gradients. The distributions of marker enzymes for the principal subcellular organelles were determined in the gradients and related to the specific activities in the homogenates. There were increased activities of the brush border carbohydrases zinc-resistant alpha-glucosidase, maltase and sucrase in the pancreatic insufficient animals, but no change in lactase activity. The activity of gamma-glutamyl transferase was also higher in the affected group; the activities of two other brush border enzymes, alkaline phosphatase and leucyl-beta-naphthylamidase, however, were unaltered. These findings with an increase in the modal density of the brush border from 1.20 to 1.22 are consistent with an enhanced glycoprotein content of the microvillus membrane. There were also rises in the activities of lysosomal enzymes. N-Acetyl-beta-glucosaminidase activity was increased in the soluble fractions and the percentage latent enzyme activity was reduced, findings indicative of an increased fragility of the lysosomal membrane. There were no marked alterations in the activities or density gradient distributions of marker enzymes for the other organelles, stressing the specificity of the changes in the brush borders and lysosomes. These findings are compatible with the degradation of certain exposed brush border proteins by pancreatic proteases and suggest that when this is defective, intracellular degradative mechanisms may be stimulated. PMID:488765

Batt, R M; Bush, B M; Peters, T J

1979-08-01

232

Determination of naturally occurring MTBE biodegradation by analysing metabolites and biodegradation by-products  

NASA Astrophysics Data System (ADS)

Methyl tert-butyl ether (MTBE) is one of the main additives in gasoline. Its degradation is known to be difficult in natural environments. In this study, significant MTBE degradation is demonstrated at a contaminated site in Leuna (eastern Germany). Since the extent of the plume appeared to be constant over the last 5 years, an extended study was performed to elucidate the degradation processes. Special attention was paid to the production, accumulation and degradation of metabolites and by-products. Groundwater samples from 105 monitoring wells were used to measure 20 different substances. During the degradation process, several intermediates such as tert-butyl alcohol (TBA), tert-butyl formate, formate and lactate were produced. However, the potentially carcinogenic by-product methacrylate was not detected in several hundred samples. At the Leuna site, MTBE degradation occurred under microaerobic conditions. In contrast to hydrocarbons and BTEX, there was no evidence for anaerobic MTBE degradation. Among the degradation products, TBA was found to be a useful intermediate to identify MTBE degradation, at least under microaerobic conditions. TBA accumulation was strongly correlated to MTBE degradation according to the kinetic properties of both degradation processes. Since maximum degradation rates ( vmax) and km values were higher for MTBE ( vmax = 2.3 mg/l/d and km = 3.2 mg/l) than for TBA ( vmax = 1.35 mg/l/d and km = 0.05 mg/l), TBA significantly accumulated as an intermediate by-product. The field results were supported by bench scale model aquifer experiments.

Martienssen, Marion; Fabritius, Holger; Kukla, Stefan; Balcke, Gerd U.; Hasselwander, Eyk; Schirmer, Mario

2006-09-01

233

Regulation of naturally occurring antisense RNA of myosin heavy chain (MyHC) in neonatal cardiomyocytes.  

PubMed

Naturally occurring antisense RNA has been detected for a range of eukaryotic genes. Its abundance compared to levels of its complementary sense mRNA appears to be a factor indicating its possible regulatory function. In previous studies, we detected appreciable levels of antisense RNA against the two isoforms (alpha and beta) of the heavy myosin-chain (MyHC) in the myocardium of rats. If this is to play a significant role in gene expression antisense levels should vary in response to external and internal cellular influences. Recently, a bidirectional promoter located in the alpha/beta MyHC intergenic region was described, which was proposed to regulate coordinated transcription of alpha-MyHC sense and beta-MyHC antisense. To study MyHC antisense regulation in neonatal heart, we investigated cultivated myocytes stimulated with either trijodthyronin (T3) as an inductor of alpha-MyHC or phenylephrine with stimulation of beta-MyHC. RNA-quantification of sense and antisense transcripts of both isoforms was performed by real-time RT-PCR. Stimulation by T3 led to an induction of both sense and antisense of alpha-MyHC and to a decrease of beta-MyHC sense and antisense. Phenylephrine increased sense and antisense beta-MyHC but reduced antisense alpha-MyHC. The sense/antisense of alpha- and beta-MyHC ratio was unchanged compared to control. Results indicate a coregulation of sense and antisense MyHC RNA under stimulation of T3 and phenylephrine in neonatal cardiomyocytes. PMID:15578571

Luther, H P; Bartsch, H; Morano, I; Podlowski, S; Baumann, G

2005-03-01

234

Naturally occurring secondary nutritional hyperparathyroidism in cattle egrets (Bubulcus ibis) from central Texas.  

PubMed

Naturally occurring secondary nutritional hyperparathyroidism is described in the nestlings of two colonies of cattle egrets (Bubulcus ibis) from Central Texas (Bryan and San Antonio, Texas, USA). Nestlings from a third colony (Waco, Texas, USA) were collected in a subsequent year for comparison. Birds from the first two colonies consistently had severe osteopenia and associated curving deformities and folding fractures of their long bones. These birds also had reduced bone ash, increased osteoclasia, a marked decrease in osteoblast activity, variable lengthening and shortening of the hypertrophic zone of the epiphyseal cartilage, decreased and disorganized formation of new bone, and a marked hypertrophy and hyperplasia of the parathyroid glands as compared to birds collected from the third colony. Fibrous osteodystrophy was found in all of the birds from San Antonio and Bryan. Evidence of moderate to severe calcium deficiency was also identified in 33% of the cattle egrets collected from Waco. Gut contents of affected chicks contained predominately grasshoppers and crickets; vertebrate prey items were absent from the Bryan birds. Grasshoppers and crickets collected from fields frequented by the adult egrets in 1994 had 0.12-0.28% calcium and 0.76-0.81% phosphorus. Pooled grasshoppers and crickets collected during a subsequent wet early spring averaged 0.24% calcium and 0.65% phosphorus. Although the phosphorus content of the insect prey was adequate for growth, calcium was approximately one-third the minimum calcium requirement needed for growth for other species of birds. It was postulated that cattle egrets breeding in Central Texas have expanded their range into habitat that contains less vertebrate prey, and as a result, many nestling egrets are being fed diets that contain suboptimal calcium. Therefore, in years where vertebrate prey is scarce and forage for insect prey is reduced in calcium, nestling egrets are at risk for developing secondary nutritional hyperparathyroidism. PMID:16107676

Phalen, David N; Drew, Mark L; Contreras, Cindy; Roset, Kimberly; Mora, Miguel

2005-04-01

235

Naturally occurring 2'-hydroxyl-substituted flavonoids as high-affinity benzodiazepine site ligands.  

PubMed

Screening of traditional medicines has proven invaluable to drug development and discovery. Utilizing activity-guided purification, we previously reported the isolation of a list of flavonoids from the medicinal herb Scutellaria baicalensis Georgi, one of which manifested an affinity for the benzodiazepine receptor (BDZR) comparable to that of the synthetic anxiolytic diazepam (K(i)=6.4 nM). In the present study, this high-affinity, naturally occurring flavonoid derivative, 5,7,2'-trihydroxy-6,8-dimethoxyflavone (K36), was chosen for further functional and behavioral characterization. K36 inhibited [3H]flunitrazepam binding to native BDZR with a K(i) value of 6.05 nM. In electrophysiological experiments K36 potentiated currents mediated by rat recombinant alpha(1)beta(2)gamma(2) GABA(A) receptors expressed in Xenopus oocytes. This potentiation was characterized by a threshold (1 nM) and half-maximal stimulation (24 nM) similar to diazepam. This enhancement was demonstrated to act via the BDZR, since co-application of 1 microM of the BDZR antagonist Ro15-1788 reversed the potentiation. Oral administration of K36 produced significant BDZR-mediated anxiolysis in the mice elevated plus-maze, which was abolished upon co-administration of Ro15-1788. Sedation, myorelaxation and motor incoordination were not observed in the chosen dosage regimen. Structure-activity relationships utilizing synthetic flavonoids with different 2' substituents on the flavone backbone supported that 2'-hydroxyl-substitution is a critical moiety on flavonoids with regard to BDZR affinities. These results further underlined the potential of flavonoids as therapeutics for the treatment of BDZR-associated syndromes. PMID:14637197

Huen, Michael S Y; Hui, Kwok-Min; Leung, Justin W C; Sigel, Erwin; Baur, Roland; Wong, J Tze-Fei; Xue, Hong

2003-12-15

236

Staphylococcal Phenotypes Induced by Naturally Occurring and Synthetic Membrane-Interactive Polyphenolic ?-Lactam Resistance Modifiers  

PubMed Central

Galloyl catechins, in particular (-)-epicatechin gallate (ECg), have the capacity to abrogate ?-lactam resistance in methicillin-resistant strains of Staphylococcus aureus (MRSA); they also prevent biofilm formation, reduce the secretion of a large proportion of the exoproteome and induce profound changes to cell morphology. Current evidence suggests that these reversible phenotypic traits result from their intercalation into the bacterial cytoplasmic membrane. We have endeavoured to potentiate the capacity of ECg to modify the MRSA phenotype by stepwise removal of hydroxyl groups from the B-ring pharmacophore and the A:C fused ring system of the naturally occurring molecule. ECg binds rapidly to the membrane, inducing up-regulation of genes responsible for protection against cell wall stress and maintenance of membrane integrity and function. Studies with artificial membranes modelled on the lipid composition of the staphylococcal bilayer indicated that ECg adopts a position deep within the lipid palisade, eliciting major alterations in the thermotropic behaviour of the bilayer. The non-galloylated homolog (-)-epicatechin enhanced ECg-mediated effects by facilitating entry of ECg molecules into the membrane. ECg analogs with unnatural B-ring hydroxylation patterns induced higher levels of gene expression and more profound changes to MRSA membrane fluidity than ECg but adopted a more superficial location within the bilayer. ECg possessed a high affinity for the positively charged staphylococcal membrane and induced changes to the biophysical properties of the bilayer that are likely to account for its capacity to disperse the cell wall biosynthetic machinery responsible for ?-lactam resistance. The ability to enhance these properties by chemical modification of ECg raises the possibility that more potent analogs could be developed for clinical evaluation. PMID:24699700

Palacios, Lucia; Rosado, Helena; Micol, Vicente; Rosato, Adriana E.; Bernal, Patricia; Arroyo, Raquel; Grounds, Helen; Anderson, James C.; Stabler, Richard A.; Taylor, Peter W.

2014-01-01

237

Effect of leachability on environmental risk assessment for naturally occurring radioactive materials in petroleum oil fields.  

PubMed

Elevated concentrations of naturally occurring radioactive material (NORM), including 238U, 232Th, and their progeny found in underground geologic deposits, are often encountered during crude oil recovery. Radium, the predominant radionuclide brought to the surface with the crude oil and produced water, co-precipitates with barium in the form of complex compounds of sulfates, carbonates, and silicates found in sludge and scale. These NORM deposits are highly stable and very insoluble under ambient conditions at the earth's surface. However, the co-precipitated radium matrix is not thermodynamically stable at reducing conditions which may enable a fraction of the radium to eventually be released to the environment. Although the fate of radium in uranium mill tailings has been studied extensively, the leachability of radium from crude oil NORM deposits exposed to acid-rain and other aging processes is generally unknown. The leachability of radium from NORM contaminated soil collected at a contaminated oil field in eastern Kentucky was determined using extraction fluids having wide range of pH reflecting different extreme environmental conditions. The average 226Ra concentration in the samples of soil subjected to leachability testing was 32.56 Bq g(-1) +/- 0.34 Bq g(-1). The average leaching potential of 226Ra observed in these NORM contaminated soil samples was 1.3% +/- 0.46% and was independent of the extraction fluid. Risk assessment calculations using the family farm scenario show that the annual dose to a person living and working on this NORM contaminated soil is mainly due to external gamma exposure and radon inhalation. However, waterborne pathways make a non-negligible contribution to the dose for the actual resident families living on farmland with the type of residual NORM contamination due to crude oil recovery operations. PMID:10647985

Rajaretnam, G; Spitz, H B

2000-02-01

238

Antibacterial Activities of Naturally Occurring Compounds against Mycobacterium avium subsp. paratuberculosis?  

PubMed Central

The antibacterial activities of 18 naturally occurring compounds (including essential oils and some of their isolated constituents, apple and green tea polyphenols, and other plant extracts) against three strains of Mycobacterium avium subsp. paratuberculosis (a bovine isolate [NCTC 8578], a raw-milk isolate [806R], and a human isolate [ATCC 43015]) were evaluated using a macrobroth susceptibility testing method. M. avium subsp. paratuberculosis was grown in 4 ml Middlebrook 7H9 broth containing 10% oleic acid-albumin-dextrose-catalase, 0.05% Tween 80 (or 0.2% glycerol), and 2 ?g/ml mycobactin J supplemented with five concentrations of each test compound. The changes in the optical densities of the cultures at 600 nm as a measure of CFU were recorded at intervals over an incubation period of 42 days at 37°C. Six of the compounds were found to inhibit the growth of M. avium subsp. paratuberculosis. The most effective compound was trans-cinnamaldehyde, with a MIC of 25.9 ?g/ml, followed by cinnamon oil (26.2 ?g/ml), oregano oil (68.2 ?g/ml), carvacrol (72.2 ?g/ml), 2,5-dihydroxybenzaldehyde (74 ?g/ml), and 2-hydroxy-5-methoxybenzaldehyde (90.4 ?g/ml). With the exception of carvacrol, a phenolic compound, three of the four most active compounds are aldehydes, suggesting that the structure of the phenolic group or the aldehyde group may be important to the antibacterial activity. No difference in compound activity was observed between the three M. avium subsp. paratuberculosis strains studied. Possible mechanisms of the antimicrobial effects are discussed. PMID:18676709

Wong, Stella Y. Y.; Grant, Irene R.; Friedman, Mendel; Elliott, Christopher T.; Situ, Chen

2008-01-01

239

Diversity of Opines and Opine-Catabolizing Bacteria Isolated from Naturally Occurring Crown Gall Tumors  

PubMed Central

The diversity of opines from 43 naturally occurring crown gall tumors on several plant species was analyzed for the presence of agropine, chrysopine, iminodiacid, an unidentified leucinopine-like iminodiacid (IDA-B), mannopine, octopine, nopaline, DL- and LL-succinamopine, leucinopine and heliopine. Opine utilization patterns of agrobacteria and fluorescent pseudomonads resident in a tumor were then analyzed and compared for agreement with the opine isolated from that tumor. Nopaline was the most common opine found and was detected in tumors from cherry, blackberry, grape, and plum. Octopine was not found, although octopine-catabolizing bacteria were isolated from several tumors. A new, previously undescribed iminodiacid of the succinamopine-leucinopine type (provisionally designated IDA-B) was isolated from tumors of wild blackberry. Field tumors from apple, blueberry and grape yielded no detectable opines, even though opine-utilizing bacteria were present. Bacterial isolates from plum and cherry showed the best correspondence between the opine in tumors (nopaline) and the presence of bacteria that catabolized that opine. However, several unusual opine catabolic combinations were identified, including isolates that catabolized a variety of opines but were nonpathogenic. More variability was observed among isolates from field tumors on the remaining plant species. We isolated novel mannopine-nopaline type agrobacteria from field tumors of cherry, plum and blackberry that induced tumors containing either mannopine (plus agropine) or nopaline, but not both. Epidemiologically, the galled plants from an area were not of clonal origin (same Ti plasmid), indicating that the field tumors from a small area were incited by more than one type of Ti plasmid. PMID:16535484

Moore, L. W.; Chilton, W. S.; Canfield, M. L.

1997-01-01

240

Estimated trichloroethene transformation rates due to naturally occurring biodegradation in a fractured-rock aquifer  

USGS Publications Warehouse

Rates of trichloroethene (TCE) mass transformed by naturally occurring biodegradation processes in a fractured rock aquifer underlying a former Naval Air Warfare Center (NAWC) site in West Trenton, New Jersey, were estimated. The methodology included (1) dividing the site into eight elements of equal size and vertically integrating observed concentrations of two daughter products of TCE biodegradation–cis-dichloroethene (cis-DCE) and chloride–using water chemistry data from a network of 88 observation wells; (2) summing the molar mass of cis-DCE, the first biodegradation product of TCE, to provide a probable underestimate of reductive biodegradation of TCE, (3) summing the molar mass of chloride, the final product of chlorinated ethene degradation, to provide a probable overestimate of overall biodegradation. Finally, lower and higher estimates of aquifer porosities and groundwater residence times were used to estimate a range of overall transformation rates. The highest TCE transformation rates estimated using this procedure for the combined overburden and bedrock aquifers was 945 kg/yr, and the lowest was 37 kg/yr. However, hydrologic considerations suggest that approximately 100 to 500 kg/yr is the probable range for overall TCE transformation rates in this system. Estimated rates of TCE transformation were much higher in shallow overburden sediments (approximately 100 to 500 kg/yr) than in the deeper bedrock aquifer (approximately 20 to 0.15 kg/yr), which reflects the higher porosity and higher contaminant mass present in the overburden. By way of comparison, pump-and-treat operations at the NAWC site are estimated to have removed between 1,073 and 1,565 kg/yr of TCE between 1996 and 2009.

Chapelle, Francis H.; Lacombe, Pierre J.; Bradley, Paul M.

2012-01-01

241

Initial evaluation of nighttime restlessness in a naturally occurring canine model of osteoarthritis pain  

PubMed Central

Chronic pain due to osteoarthritis (OA) can lead to significant disruption of sleep and increased restlessness. Our objective was to assess whether naturally occurring canine OA is associated with nighttime restlessness and so has potential as a model of OA-associated sleep disturbance. The study was designed as a two-part prospective masked, placebo-controlled study using client-owned dogs (Part A n = 60; Part B n = 19). Inclusion criteria consisted of OA-associated joint pain and mobility impairment. The primary outcome measure for both parts was nighttime accelerometry. In Part B, quality of sleep was assessed using a clinical metrology instrument (Sleep and Night Time Restlessness Evaluation Score, SNoRE). Part A included dogs receiving two weeks of non-steroidal anti-inflammatory drug (NSAID) preceded with two weeks of no treatment. Part B was a crossover study, with NSAID/placebo administered for two weeks followed by a washout period of one week and another two weeks of NSAID/placebo. Repeated measures analysis of variance was used to assess differences between baseline and treatment. There were no significant changes in accelerometry-measured nighttime activity as a result of NSAID administration. SNoRE measures indicated significant improvements in aspects of the quality of nighttime sleep that did not involve obvious movement. These results reflect the few similar studies in human OA patients. Although accelerometry does not appear to be useful, this model has potential to model the human pain-related nighttime sleep disturbance, and other outcome measures should be explored in this model. PMID:25722957

Knazovicky, David; Tomas, Andrea; Motsinger-Reif, Alison

2015-01-01

242

Identification of Myeloid Derived Suppressor Cells in Dogs with Naturally Occurring Cancer  

PubMed Central

Dogs with naturally occurring cancer represent an important large animal model for drug development and testing novel immunotherapies. However, poorly defined immunophenotypes of canine leukocytes have limited the study of tumor immunology in dogs. The accumulation of myeloid derived suppressor cells (MDSCs) is known to be a key mechanism of immune suppression in tumor-bearing mice and in human patients. We sought to identify MDSCs in the blood of dogs with cancer. Peripheral blood mononuclear cells (PBMCs) from dogs with advanced or early stage cancer and from age-matched healthy controls were analyzed by flow cytometry and microscopy. Suppressive function was tested in T cell proliferation and cytokine elaboration assays. Semi-quantitative RT-PCR was used to identify potential mechanisms responsible for immunosuppression. PBMCs from dogs with advanced or metastatic cancer exhibited a significantly higher percentage of CD11b+CD14?MHCII? cells compared to dogs diagnosed with early stage non-metastatic tumors and healthy dogs. These CD11b+ CD14?MHCII? cells constitute a subpopulation of activated granulocytes that co-purify with PBMCs, display polymorphonuclear granulocyte morphology, and demonstrate a potent ability to suppress proliferation and IFN-? production in T cells from normal and tumor-bearing donors. Furthermore, these cells expressed hallmark suppressive factors of human MDSC including ARG1, iNOS2, TGF-? and IL-10. In summary our data demonstrate that MDSCs accumulate in the blood of dogs with advanced cancer and can be measured using this three-marker immunophenotype, thereby enabling prospective studies that can monitor MDSC burden. PMID:22428007

Goulart, Michelle R.; Pluhar, G. Elizabeth; Ohlfest, John R.

2012-01-01

243

Naturally occurring secondary nutritional hyperparathyroidism in cattle egrets (Bubulcus ibis) from Central Texas  

USGS Publications Warehouse

Naturally occurring secondary nutritional hyperparathyroidism is described in the nestlings of two colonies of cattle egrets (Bubulcus ibis) from Central Texas (Bryan and San Antonio, Texas, USA). Nestlings from a third colony (Waco, Texas, USA) were collected in a subsequent year for comparison. Birds from the first two colonies consistently had severe osteopenia and associated curving deformities and folding fractures of their long bones. These birds also had reduced bone ash, increased osteoclasia, a marked decrease in osteoblast activity, variable lengthening and shortening of the hypertrophic zone of the epiphyseal cartilage, decreased and disorganized formation of new bone, and a marked hypertrophy and hyperplasia of the parathyroid glands as compared to birds collected from the third colony. Fibrous osteodystrophy was found in all of the birds from San Antonio and Bryan. Evidence of moderate to severe calcium deficiency was also identified in 33% of the cattle egrets collected from Waco. Gut contents of affected chicks contained predominately grasshoppers and crickets; vertebrate prey items were absent from the Bryan birds. Grasshoppers and crickets collected from fields frequented by the adult egrets in 1994 had 0.12-0.28% calcium and 0.76-0.81% phosphorus. Pooled grasshoppers and crickets collected during a subsequent wet early spring averaged 0.24% calcium and 0.65% phosphorus. Although the phosphorus content of the insect prey was adequate for growth, calcium was approximately one-third the minimum calcium requirement needed for growth for other species of birds. It was postulated that cattle egrets breeding in Central Texas have expanded their range into habitat that contains less vertebrate prey, and as a result, many nestling egrets are being fed diets that contain suboptimal calcium. Therefore, in years where vertebrate prey is scarce and forage for insect prey is reduced in calcium, nestling egrets are at risk for developing secondary nutritional hyperparathyroidism. ?? Wildlife Disease Association 2005.

Phalen, D.N.; Drew, M.L.; Contreras, C.; Roset, K.; Mora, M.

2005-01-01

244

Polyporus tenuiculus: a new naturally occurring mushroom that can be industrially cultivated on agricultural waste.  

PubMed

Polyporus tenuiculus is a naturally occurring species from Central and South America that is consumed by different ethnic groups in the region. To determine the optimal conditions for fruiting body production, two strains were assayed on wheat straw and sawdust with or without supplements. Sixty days of incubation at 25 degrees C were needed to produce a solid block. The highest yield was obtained with strain ICFC 383/00 grown on supplemented willow sawdust. In a second experiment the strain ICFC 383/00 and different supplements were used to improve the biological efficiency (BE) and to determine the quality traits and its biodegradation capacity. The highest yields were obtained on sawdust with 25% of supplements reaching 82.7% of BE. Supplements raised the number of flushes, generally from four to five, contributing to increased yields. The type of substrate had a significant effect on fruiting body diameters of P. tenuiculus, and the largest mushrooms were harvested on supplemented substrate with the highest BE coinciding with the highest dry matter loss in substrates. P. tenuiculus showed a capacity to degrade sawdust, causing a decrease of 67.2-74.5% in cellulose, 80.4-85.7% in hemicellulose, and 60.6-66.2% in lignin content at the end of the cultivation cycle. The decrease in hemicellulose was relatively greater than that of cellulose and lignin on supplemented substrates. This is the first report of the cultivation of P. tenuiculus on lignocellulosic waste, and it is a promising species both for commercial production and for its potential use in the degradation of other biowastes. PMID:19212788

Omarini, Alejandra; Lechner, Bernardo E; Albertó, Edgardo

2009-05-01

245

Demonstration of significant abiotic iron isotope fractionation in nature  

USGS Publications Warehouse

Field and laboratory studies reveal that the mineral ferrihydrite, formed as a result of abiotic oxidation of aqueous ferrous to ferric Fe, contains Fe that is isotopically heavy relative to coexisting aqueous Fe. Because the electron transfer step of the oxidation process at pH >5 is essentially irreversible and should favor the lighter Fe isotopes in the ferric iron product, this result suggests that relatively heavy Fe isotopes are preferentially partitioned into the readily oxidized Fe(II)(OH)x(aq) species or their transition complexes prior to oxidation. The apparent Fe isotope fractionation factor, ??ferrihydrite-water, depends primarily on the relative abundances of the Fe(II)(aq) species. This study demonstrates that abiotic processes can fractionate the Fe isotopes to the same extent as biotic processes, and thus Fe isotopes on their own do not provide an effective biosignature.

Bullen, T.D.; White, A.F.; Childs, C.W.; Vivit, D.V.; Schultz, M.S.

2001-01-01

246

A comparison of the induced and naturally occurring juvenile hormone esterases from last instar larvae of Trichoplusia ni  

Microsoft Academic Search

During the last larval instar of Trichoplusia ni two naturally occurring peaks of juvenile hormone esterase activity are present. After a critical period, juvenile hormone esterase activity can be induced in normal and ligated larvae by the topical application of juvenile hormone or juvenoids. The natural and artificially induced juvenile hormone esterases are similarly inhibited by a selected group of

THOMAS C. SPARKS; BRUCE D. HAMMOCK

1979-01-01

247

AcuteToxicological Responses of Fischer Rats to Naturally Occurring Asbestos Samples from the United States and Canada  

EPA Science Inventory

The potential public health issues related to exposure to natural asbestos deposits (commonly termed naturally occurring asbestos, NO A) has gained the regulatory and media spotlight in recent years. Arguably the most well known example is Libby, Montana, the site of the largest ...

248

Zinc isotope variations in natural and cultured marine phytoplankton.  

NASA Astrophysics Data System (ADS)

Zn is an essential micronutrient for marine phytoplankton. Zn distribution in the ocean is largely controlled by biological uptake, being drawn down from several nanomolar concentrations in the deep ocean to picomolar concentrations in the surface ocean. Zn isotopes may record this biological activity based on the preferential uptake of lighter Zn isotopes by phytoplankton. Marechal et. al. (2000) attribute a seasonal cycle in the Zn isotope composition of sediment trap material and global variations in the Zn isotope composition of manganese nodules to this biological fractionation. To better understand the processes controlling the distribution of Zn isotopes in the ocean, the isotopic composition of phytoplankton was investigated. In-situ plankton were collected by trace metal clean plankton tows from both the Atlantic and Pacific Oceans. In a region close to a continental source of Zn, approximately 300 km off the coast of Brazil (7.4 S, 31.4 W), the isotope composition of the plankton tow material closely resembles that of continental material. The isotopic composition of plankton tows from more remote locations in the open ocean may better record the effects of biological cycling. Additional samples from the Atlantic, as well as samples from the central Pacific near Hawaii and the North Pacific are being processed. This data may be used to better understand how biological processes control the global distribution of Zn isotopes in the oceans.

John, S. G.; Bergquist, B. A.; Boyle, E. A.

2004-12-01

249

Nitrate dynamics in natural plants: insights based on the concentration and natural isotope abundances of tissue nitrate  

PubMed Central

The dynamics of nitrate (NO?3), a major nitrogen (N) source for natural plants, has been studied mostly through experimental N addition, enzymatic assay, isotope labeling, and genetic expression. However, artificial N supply may not reasonably reflect the N strategies in natural plants because NO?3 uptake and reduction may vary with external N availability. Due to abrupt application and short operation time, field N addition, and isotopic labeling hinder the elucidation of in situ NO?3-use mechanisms. The concentration and natural isotopes of tissue NO?3 can offer insights into the plant NO?3 sources and dynamics in a natural context. Furthermore, they facilitate the exploration of plant NO?3 utilization and its interaction with N pollution and ecosystem N cycles without disturbing the N pools. The present study was conducted to review the application of the denitrifier method for concentration and isotope analyses of NO?3 in plants. Moreover, this study highlights the utility and advantages of these parameters in interpreting NO?3 sources and dynamics in natural plants. We summarize the major sources and reduction processes of NO?3 in plants, and discuss the implications of NO?3 concentration in plant tissues based on existing data. Particular emphasis was laid on the regulation of soil NO?3 and plant ecophysiological functions in interspecific and intra-plant NO?3 variations. We introduce N and O isotope systematics of NO?3 in plants and discuss the principles and feasibilities of using isotopic enrichment and fractionation factors; the correlation between concentration and isotopes (N and O isotopes: ?18O and ?17O); and isotope mass-balance calculations to constrain sources and reduction of NO?3 in possible scenarios for natural plants are deliberated. Finally, we offer a preliminary framework of intraplant ?18O-NO?3 variation, and summarize the uncertainties in using tissue NO?3 parameters to interpret plant NO?3 utilization. PMID:25101106

Liu, Xue-Yan; Koba, Keisuke; Makabe, Akiko; Liu, Cong-Qiang

2014-01-01

250

Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry  

USGS Publications Warehouse

The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

Meier, A.L.

1982-01-01

251

Naturally Occurring Differences in CENH3 Affect Chromosome Segregation in Zygotic Mitosis of Hybrids  

PubMed Central

The point of attachment of spindle microtubules to metaphase chromosomes is known as the centromere. Plant and animal centromeres are epigenetically specified by a centromere-specific variant of Histone H3, CENH3 (a.k.a. CENP-A). Unlike canonical histones that are invariant, CENH3 proteins are accumulating substitutions at an accelerated rate. This diversification of CENH3 is a conundrum since its role as the key determinant of centromere identity remains a constant across species. Here, we ask whether naturally occurring divergence in CENH3 has functional consequences. We performed functional complementation assays on cenh3-1, a null mutation in Arabidopsis thaliana, using untagged CENH3s from increasingly distant relatives. Contrary to previous results using GFP-tagged CENH3, we find that the essential functions of CENH3 are conserved across a broad evolutionary landscape. CENH3 from a species as distant as the monocot Zea mays can functionally replace A. thaliana CENH3. Plants expressing variant CENH3s that are fertile when selfed show dramatic segregation errors when crossed to a wild-type individual. The progeny of this cross include hybrid diploids, aneuploids with novel genetic rearrangements and haploids that inherit only the genome of the wild-type parent. Importantly, it is always chromosomes from the plant expressing the divergent CENH3 that missegregate. Using chimeras, we show that it is divergence in the fast-evolving N-terminal tail of CENH3 that is causing segregation errors and genome elimination. Furthermore, we analyzed N-terminal tail sequences from plant CENH3s and discovered a modular pattern of sequence conservation. From this we hypothesize that while the essential functions of CENH3 are largely conserved, the N-terminal tail is evolving to adapt to lineage-specific centromeric constraints. Our results demonstrate that this lineage-specific evolution of CENH3 causes inviability and sterility of progeny in crosses, at the same time producing karyotypic variation. Thus, CENH3 evolution can contribute to postzygotic reproductive barriers. PMID:25622028

Maheshwari, Shamoni; Tan, Ek Han; West, Allan; Franklin, F. Chris H.; Comai, Luca

2015-01-01

252

Elevated Bacterial Abundance in Laboratory-Grown and Naturally Occurring Frost Flowers Under Late Winter Conditions  

NASA Astrophysics Data System (ADS)

Sea ice has been identified as an important microbial habitat, with bacteria and other microbes concentrated in the brine inclusions between ice crystals. Frost flowers, thought to draw brine from underlying sea ice, have not been characterized from a microbial standpoint. To test whether frost flowers serve as an upward vector of bacteria contained within sea ice brines we grew frost flowers in a freezer laboratory (air temperature of -21°C) from saline water spiked with the mesophilic (and thus passive under experimental conditions) bacterium Halomonas pacifica. Salinity of melted samples was measured and bacterial abundance determined by epifluorescent microscopy. Bacterial counts scaled to ice-melt volume averaged 2.82 x 106 ml-1 for frost flowers, compared to 9.47 x 105 ml-1 for underlying ice (3 x higher). Bacterial counts also correlated significantly with salinity (maximum value of 62.5 psu) for frost flowers, brine skim, and ice (df = 17, r = 0.59, p < 0.0001). Segregation coefficients were calculated to describe the efficiency of transport of both cells and salt from the starting solution into frost flowers. From these coefficients an enrichment index was calculated to test for bacterial concentration into frost flowers at a different rate than salt. Analysis with a Student’s T-test (df = 24, t = 0.306, p = .76) indicated that cells and salt were not transported into frost flowers with a significantly different efficiency. To test these findings in the field we then collected frost flowers (and related samples) from new sea ice near Barrow, Alaska in April 2009. Bacterial counts were significantly elevated (again, a 3-fold increase) in natural frost flowers (mean = 2.73 x 105 ml-1) compared to underlying sea ice (mean = 8.46 x 104 cells ml-1). For all field samples collected (frost flowers, underlying brine skim and sea ice, as well as snow), bacterial abundance correlated significantly with salinity (maximum value 124 psu, df = 40, r = 0.60, p < 0.0001). The presence of elevated numbers of bacteria in frost flowers may have implications for the previously observed chemical reactions that take place in them, especially if microbial activity can be shown to occur in this unique low temperature, low water activity microbial habitat.

Bowman, J. S.; Deming, J. W.

2009-12-01

253

Manufactured Home Testing in Simulated and Naturally Occurring High Winds for WCTE Conference  

SciTech Connect

A typical double-wide manufactured home was tested in simulated and naturally occurring high winds to understand structural behavior and improve performance during severe windstorms. Seven (7) lateral load tests were conducted on a double-wide manufactured home at a remote field test site in Wyoming. An extensive instrumentation package monitored the overall behavior of the home and collected data vital to validating computational software for the manufactured housing industry. The tests were designed to approach the design load of the home without causing structural damage, thus allowing the behavior of the home to be accessed when the home was later exposed to high winds (to 80-mph). The data generally show near-linear initial system response with significant non-linear behavior as the applied loads increase. Load transfer across the marriage line is primarily compression. Racking, while present, is very small. Interface slip and shear displacement along the marriage line are nearly insignificant. Horizontal global displacements reached 0.6 inch. These tests were designed primarily to collect data necessary to calibrate a desktop analysis and design software tool, MHTool, under development at the Idaho National Laboratory specifically for manufactured housing. Currently available analysis tools are, for the most part, based on methods developed for "stick built" structures and are inappropriate for manufactured homes. The special materials utilized in manufactured homes, such as rigid adhesives used in the connection of the sheathing materials to the studs, significantly alter the behavior of manufactured homes under lateral loads. Previous full scale tests of laterally loaded manufactured homes confirm the contention that conventional analysis methods are not applicable. System behavior dominates the structural action of manufactured homes and its prediction requires a three dimensional analysis of the complete unit, including tie-downs. This project was sponsored by the US Department of Energy, US Department of Housing and Urban Development, and the Manufactured Housing Institute. The results of this research can lead to savings in annual losses of life and property by providing validated information to enable the advancement of code requirements and by developing engineering software that can predict and optimize wind resistance.

William D. Richins; Thomas K. Larson; Jeffrey M. Lacy; Ryan G. Kobbe

2006-08-01

254

Naturally Occurring Differences in CENH3 Affect Chromosome Segregation in Zygotic Mitosis of Hybrids.  

PubMed

The point of attachment of spindle microtubules to metaphase chromosomes is known as the centromere. Plant and animal centromeres are epigenetically specified by a centromere-specific variant of Histone H3, CENH3 (a.k.a. CENP-A). Unlike canonical histones that are invariant, CENH3 proteins are accumulating substitutions at an accelerated rate. This diversification of CENH3 is a conundrum since its role as the key determinant of centromere identity remains a constant across species. Here, we ask whether naturally occurring divergence in CENH3 has functional consequences. We performed functional complementation assays on cenh3-1, a null mutation in Arabidopsis thaliana, using untagged CENH3s from increasingly distant relatives. Contrary to previous results using GFP-tagged CENH3, we find that the essential functions of CENH3 are conserved across a broad evolutionary landscape. CENH3 from a species as distant as the monocot Zea mays can functionally replace A. thaliana CENH3. Plants expressing variant CENH3s that are fertile when selfed show dramatic segregation errors when crossed to a wild-type individual. The progeny of this cross include hybrid diploids, aneuploids with novel genetic rearrangements and haploids that inherit only the genome of the wild-type parent. Importantly, it is always chromosomes from the plant expressing the divergent CENH3 that missegregate. Using chimeras, we show that it is divergence in the fast-evolving N-terminal tail of CENH3 that is causing segregation errors and genome elimination. Furthermore, we analyzed N-terminal tail sequences from plant CENH3s and discovered a modular pattern of sequence conservation. From this we hypothesize that while the essential functions of CENH3 are largely conserved, the N-terminal tail is evolving to adapt to lineage-specific centromeric constraints. Our results demonstrate that this lineage-specific evolution of CENH3 causes inviability and sterility of progeny in crosses, at the same time producing karyotypic variation. Thus, CENH3 evolution can contribute to postzygotic reproductive barriers. PMID:25622028

Maheshwari, Shamoni; Tan, Ek Han; West, Allan; Franklin, F Chris H; Comai, Luca; Chan, Simon W L

2015-02-01

255

Increased carbon uptake in marine sediment enabled by naturally occurring electrical conductors  

NASA Astrophysics Data System (ADS)

Reduction-oxidation (redox) gradients are common across marine sediment-water interfaces and result from microbially-mediated reactions such as the oxidation of organic matter coupled to reduction of electron acceptors. Most microbes living in sediments do not have direct access to oxygen in their immediate environment, however it has recently been shown that sulfide-oxidizing microbes may employ extracellular electron transfer (EET) to couple the oxidation of sulfide in the anoxic zone to reduction of oxygen at the sediment-water interface located several centimeters away. However, no mechanisms for this observed phenomenon have been validated. Accordingly, we tested the hypothesis that conductive minerals in marine sediment (specifically pyrite) can couple spatially separated redox reactions such as anaerobic respiration and oxygen reduction. Marine sediment was amended with naturally occurring pyrite in varying concentrations (0, 2, 10 and 50 weight-percent) and then incubated with 10 ?M 13C-labeled acetate. After six hours, the treatments with the greatest amount of added pyrite showed the greatest incorporation of acetate from the labeled pool. The fraction of labeled acetate incorporation more than doubled in the 10 and 50 weight-percent treatments compared to the control sediment. We also designed a circuit to investigate the electrical conductivity of the sediment treatments as a function of added pyrite. A potentiostat was used to establish a known voltage across a sediment column and current was measured. Resistance (the inverse of conductance) was calculated from a linear fit of current data over a range of voltages ranging from 0.5 to 1.0 V. The treatments with added pyrite had lower resistance than background sediment, with the lowest resistance corresponding to the 50% pyrite treatment. We also examined the effect of varying pyrite content on microbial community composition using massively parallel 16S rRNA sequencing. Microbial community analyses reveal that the majority of microbes in the sediment belong to the deltaproteobacteria or gammaproteobacteria classes, which have been previously implicated in EET in laboratory and field-based bioelectrochemical studies. These data force us to reconsider the role of EET and conductive minerals in organic carbon cycling -particularly in metaliferous sediments- and suggest that EET-enabled anaerobic metabolism may represent a significant contribution to marine carbon cycling.

Nielsen, M. E.; Cahoon, D. P.; Girguis, P. R.

2011-12-01

256

Naturally occurring heavy radioactive elements in the geothermal microcosm of the Los Azufres (Mexico) volcanic complex.  

PubMed

The Los Azufres geothermal complex of central Mexico is characterized by fumaroles and boiling hot-springs. The fumaroles form habitats for extremophilic mosses and ferns. Physico-chemical measurements of two relatively pristine fumarolic microcosms point to their resemblance with the paleo-environment of earth during the Ordovician and Devonian periods. These geothermal habitats were analysed for the distribution of elemental mass fractions in the rhizospheric soil (RS), the native volcanic substrate (VS) and the sediments (S), using the new high-sensitivity technique of polarized x-ray energy dispersive fluorescence spectrometry (PEDXRF) as well as instrumental neutron activation analysis (INAA) for selected elements. This work presents the results for the naturally occurring heavy radioactive elements (NOHRE) Bi, Th and U but principally the latter two. For the RS, the density was found to be the least and the total organic matter content the most. Bi was found to be negligibly present in all substrate types. The average Th and U mass fractions in the RS were higher than in the VS and about equal to their average mass fractions in the S. The VS mass fraction of Th was higher, and of U lower, than the mass fractions in the earth's crust. In fact for the fumaroles of one site, the average RS mass fractions of these elements were higher than the averaged values for S (without considering the statistical dispersion). The immobilization of the NOHRE in the RS is brought about by the bio-geochemical processes specific to these extremophiles. Its effectiveness is such that despite the small masses of these plants, it compares with, or may sometimes exceed, the immobilization of the NOHRE in the S by the abiotic and aggressive chemical action of the hot-springs. These results indicate that the fumarolic plants are able to transform the volcanic substrate to soil and to affect the NOHRE mass fractions even though these elements are not plant nutrients. Mirrored back to the paleo times when such plant types were ubiquitous, it would mean that the first plants contributed significantly to pedogenesis and the biogeochemical recycling of even the heaviest and radioactive elements. Such plants may potentially be useful for the phytostabilisation of soil moderately contaminated by the NOHRE. Furthermore where applicable, geochronology may require taking into account the influence of the early plants on the NOHRE distributions. PMID:25464039

Abuhani, W A; Dasgupta-Schubert, N; Villaseñor, L M; García Avila, D; Suárez, L; Johnston, C; Borjas, S E; Alexander, S A; Landsberger, S; Suárez, M C

2015-01-01

257

The effect of colloid formulation on colloid osmotic pressure in horses with naturally occurring gastrointestinal disease  

PubMed Central

Background Naturally occurring gastrointestinal disease is an important cause of acute hypoproteinemia in adult horses and hydroxyethyl starch colloid fluid treatment is a component of supportive care in these cases to improve plasma volume and maintain colloid osmotic pressure (COP). The objectives of the present study were to compare 2 formulations of high molecular weight hydroxyethyl starch and their relative effect on COP, acid-base status, and survival of horses with acute hypoproteinemia secondary to gastrointestinal disease. Methods Twenty adult horses, ? 1 year of age, were prospectively enrolled, with informed client consent, if they developed acute hypoproteinemia, defined as a plasma total protein <5.0 g/dL or albumin <2.2 g/dL during hospitalization while undergoing treatment for gastrointestinal disease. Horses were randomly assigned to receive a rapid infusion of either 6% hydroxyethyl starch in 0.9% saline or 6% hydroxyethyl starch in lactated ringers solution at a dose of 10ml/kg. Venous blood gas analysis, COP, and PCV were evaluated before and after colloid administration. Results For both groups, average COP prior to treatment was 11.0 mmHg (9.7 – 12.2 mmHg) and post colloid treatment was 13.2 mmHg (12.0 -14.7 mmHg) [Normal range 18 – 22 mmHg]. COP was significantly increased with colloid treatment (p<0.001) but this increase was not significantly different between treatment groups. Venous pH did not change significantly with treatment. Twelve horses survived to hospital discharge and survival did not differ significantly between treatment groups. Conclusions Post-treatment COP improved approximately 20% regardless of the formulation used, however, values did not reach the normal range of COP observed in healthy horses. Acid-base parameters were not significantly impacted by either treatment. Further study is needed to determine how these two products compare with regards to other outcome measures. Evaluation of the relative effects of colloid formulation in horses with clinical disease is a future area of interest. PMID:25237987

2014-01-01

258

Mortality of one-week-old chickens during naturally occurring Marek's disease virus infection  

Technology Transfer Automated Retrieval System (TEKTRAN)

Marek’s disease (MD) is a serious economic disease of chickens which occurs worldwide. MD can present as one of several forms, with the most commonly occurring forms being the lymphoproliferative diseases. Under experimental conditions, an early mortality syndrome has been recognized following infec...

259

Investigation of Naturally Occurring Radio Nuclides in Shir-kuh Granites  

SciTech Connect

One of the principle natural radiation resources is Granite which can be dangerous for human because of its radiations. Based on this fact, in this research we attempt to specify the activity amount of these natural radio nuclides, existing in Shir-kuh Granite of Yazd state. To specify the activity amount of this natural radio nuclides, it has been applied the measurement method of Gamma spectroscopy using high purity Germanium (HPGe) detector.

Mazarei, Mohammad Mehdi; Zarei, Mojtaba [Department of Science, Bushehr Branch, Islamic Azad University, City of Aalishahr, Bushehr Province, Iran P.O.Box: 7519619555 (Iran, Islamic Republic of)

2011-12-26

260

The Biomimetic Synthesis and Final Structure Determination of ()-and ()-Centrolobine, Naturally Occurring Diarylheptanoid  

E-print Network

The Biomimetic Synthesis and Final Structure Determination of (þ)- and (À)-Centrolobine, Naturally cyclization of their optically active diarylheptanoid precursors. The approach is considered as a biomimetic

Rüedi, Peter

261

Investigating Tungsten Concentrations and Isotopic Compositions of Natural Water Samples from the Carson River Basin  

NASA Astrophysics Data System (ADS)

Recent studies have shown that W-isotopes may fractionate in nature1; however, the magnitude and cause of the isotopic variations are largely unknown and unconstrained. In this study, the isotopic compositions of the NIST 3163 W standard, W ore minerals, and 15 natural surface waters from Nevada's Carson River Basin were analyzed by MC-ICP-MS using external bracketing with NIST 3163 and the IUPAC 184W/183W for mass bias correction. Chemical separation procedures were developed to purify W from natural matrices and tested to assure fractionation was not introduced during column chemistry. The W isotopic compositions of these samples were measured and compared to the accepted IUPAC composition of natural W. Samples of wolframite (Fe, MnWO4) and hubnerite (MnWO4) have compositions similar to the IUPAC value but vary from the isotopic composition of NIST 3163 - particularly in 182W/183W. The isotopic compositions of the natural waters, except for an extremely evaporated sample from Soda Lake, are similar to the NIST standard. This evaporative lake, formed by a maar, has a unique chemical composition compared to other surface waters with high W (800 ± 20 ng/g) and As (1665 ± 17 ng/g) concentrations; and relatively low Fe (5.00 ± 0.13 ng/g) and Mn (0.52 ± 0.07 ng/g). These results support recent observations of natural W isotopic variation and imply that W-isotope compositions may be useful for environmental applications of stable isotope geochemistry. 1. Irisawa, K. and Hirata, T. (2006) Tungsten isotopic analysis on six geochemical reference materials using multiple collector-ICP-mass spectrometry coupled with a rhenium-external correction technique. Journal of Analytical Atomic Spectrometry 21, 1387-1395.

Wasserman, N. L.; Williams, R. W.; Kayzar, T. M.; Schorzman, K. C.

2012-12-01

262

Concentration and natural stable isotope profiles of nitrogen species in the Clara A. Fuchsman a,  

E-print Network

: Nitrogen cycle Nitrogen isotopes Anoxic basin Denitrification Anammox Nitrogen fixation Regional indexConcentration and natural stable isotope profiles of nitrogen species in the Black Sea Clara A particulate organic nitrogen (PON) and total organic nitrogen (TON) concentrations and nitrogen stable

Murray, James W.

263

Oxygen isotope signatures of transpired water vapor: the role of isotopic non-steady-state transpiration under natural conditions.  

PubMed

The oxygen isotope signature of water is a powerful tracer of water movement from plants to the global scale. However, little is known about the short-term variability of oxygen isotopes leaving the ecosystem via transpiration, as high-frequency measurements are lacking. A laser spectrometer was coupled to a gas-exchange chamber directly estimating branch-level fluxes in order to evaluate the short-term variability of the isotopic composition of transpiration (?E ) and to investigate the role of isotopic non-steady-state transpiration under natural conditions in cork-oak trees (Quercus suber) during distinct Mediterranean seasons. The measured ?(18) O of transpiration (?E ) deviated from isotopic steady state throughout most of the day even when leaf water at the evaporating sites was near isotopic steady state. High agreement was found between estimated and modeled ?E values assuming non-steady-state enrichment of leaf water. Isoforcing, that is, the influence of the transpirational ?(18) O flux on atmospheric values, deviated from steady-state calculations but daily means were similar between steady state and non-steady state. However, strong daytime isoforcing on the atmosphere implies that short-term variations in ?E are likely to have consequences for large-scale applications, for example, partitioning of ecosystem fluxes or satellite-based applications. PMID:24909361

Dubbert, Maren; Cuntz, Matthias; Piayda, Arndt; Werner, Christiane

2014-09-01

264

Review of research on impacts to biota of discharges of naturally occurring radionuclides in produced water to the marine environment.  

PubMed

Produced water has been described as the largest volume waste stream in the exploration and production process of oil and gas. It is accompanied by discharges of naturally occurring radionuclides raising concerns over the potential radiological impacts of produced water on marine biota. In the Northern European marine environment, radioactivity in produced water has received substantial attention owing to the OSPAR Radioactive Substances Strategy which aims at achieving 'concentrations in the environment near background values for naturally occurring radioactive substances'. This review provides an overview of published research on the impacts to biota from naturally occurring radionuclides discharged in produced water by the offshore oil and gas industry. In addition to summarising studies and data that deal directly with the issue of dose and effect, the review also considers studies related to the impact of added chemicals on the fate of discharged radionuclides. The review clearly illustrates that only a limited number of studies have investigated possible impacts on biota from naturally occurring radionuclides present in produced water. Hence, although these studies indicate that the risk to the environment from naturally occurring radionuclides discharged in produced water is negligible, the substantial uncertainties involved in the assessments of impact make it difficult to be conclusive. With regard to the complexity involved in the problem under consideration there is a pressing need to supplement existing data and acquire new knowledge. Finally, the present work identifies some knowledge gaps to indicate future research requirements. PMID:23022586

Hosseini, Ali; Brown, Justin E; Gwynn, Justin P; Dowdall, Mark

2012-11-01

265

Naturally Occurring Arsenic in Ground Water, Norman, Oklahoma, 2004, and Remediation Options for Produced Water  

USGS Publications Warehouse

In 2000, the U.S. Environmental Protection Agency (EPA) reviewed the arsenic drinking water standard for public water supplies. Considering the available research and statistics on the health effects of arsenic ingestion, the EPA reduced the Maximum Contaminant Level (MCL) for public drinking water from 50 micrograms per liter (?g/L) to 10 ?g/L (U.S. Environmental Protection Agency, 2001a). As a result of the more stringent standard, the EPA estimates that about 3,000 public water providers across the United States must take action to meet the new standard before it becomes effective on January 23, 2006 (U.S. Environmental Protection Agency, 2001b). The City of Norman (City) is one of several Oklahoma municipalities affected by the new arsenic standard. About 20 percent of Norman?s water is supplied by wells completed in the Central Oklahoma (Garber-Wellington) aquifer; the rest is supplied by Lake Thunderbird (fig. 1) or purchased from Oklahoma City. The Norman well field is composed of 24 active wells, and water produced from about half of the wells will not be in compliance with the new MCL (figs. 2 and 3). Chemical treatment of water with elevated arsenic is possible, but it is generally cost prohibitive. Another costly solution is simply to abandon the high-arsenic wells and replace them with new wells in low-arsenic areas. In the next phase of well construction beginning in 2005, the City plans to construct as many as 30 new wells in northeast Norman (Bryan Mitchell, City of Norman, oral commun., 2005). The new wells will replace production lost to the new arsenic standard and add new production to keep pace with rapidly growing consumer demand. Well modification to exclude arsenic-bearing water from existing wells is a more cost-effective solution, but it requires a great deal of knowledge about local aquifer properties and individual well dynamics to decide which wells are good candidates for modification. With the goal of determining if well modification can be used to bring some of Norman?s high-arsenic wells into compliance with the new arsenic standard, the EPA Office of Research and Development (ORD) initiated a three-year research project in 2003 with participation from the U.S. Geological Survey (USGS), Oklahoma State University, and the City of Norman. The primary objectives of the project are to: (1) determine where naturally occurring arsenic is entering wells by collecting water samples at different depths, (2) investigate the utility of new methods for collecting water-quality data in a pumping well, (3) better understand the stratigraphy and composition of aquifer rocks, (4) assess 10 wells for the possibility of arsenic remediation by well modification, and (5) evaluate the effectiveness of well modification in bringing marginal wells into compliance with the new arsenic MCL. The purpose of this report is to describe the occurrence of arsenic in ground water near Norman, Oklahoma, and available options for reducing arsenic concentrations in produced ground water.

Smith, S. Jerrod; Christenson, Scott

2005-01-01

266

Introduction to Chemistry and Applications in Nature of Mass Independent Isotope Effects Special Feature  

PubMed Central

Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented. PMID:24167299

Thiemens, Mark H.

2013-01-01

267

APPLICATIONS OF ENVIRONMENTAL ISOTOPES FOR WATERSHED INVESTIGATIONS  

EPA Science Inventory

Environmental isotopes include naturally-occurring nuclides that can be applied as tracers within watersheds (Sidle, 1998). Recent advances in mass spectroscopy may supplant many traditional and costly hydrometric techniques. It is now possible, for example, to utilize isotopes a...

268

Fate and bioaccumulation of soil-associated low-level naturally occurring radioactivity following disposal into a marine ecosystem. Final report  

SciTech Connect

The fate of radium (Ra) and other naturally occurring uranium-series isotopes associated with soils disposed in seawater was examined using the Marine Ecosystem Research Laboratory (MERL) controlled marine ecosystems. Thirty-seven kilograms of a soil containing approximately 400 pCi Ra-226/g from an inactive uranium ore processing plant site in Middlesex, New Jersey, were added to each of two mesocosms over five days in mid-September 1984. Radionuclide activity in these and two control mesocosms was observed for three months after the soil additions. Radioactivity in the soil appeared to be confined to discrete soil particles rather than being distributed equally on the soil particles, suggesting the source of the radioactivity was remnant ore particles.

Hunt, C.D.

1986-10-01

269

Using Natural Stable Calcium Isotopes to Rapidly Assess Changes in Bone Mineral Balance Using a Bed Rest Model to Induce Bone Loss  

NASA Technical Reports Server (NTRS)

Metabolic bone diseases like osteoporosis result from the disruption of normal bone mineral balance (BMB) resulting in bone loss. During spaceflight astronauts lose substantial bone. Bed rest provides an analog to simulate some of the effects of spaceflight; including bone and calcium loss and provides the opportunity to evaluate new methods to monitor BMB in healthy individuals undergoing environmentally induced-bone loss. Previous research showed that natural variations in the Ca isotope ratio occur because bone formation depletes soft tissue of light Ca isotopes while bone resorption releases that isotopically light Ca back into soft tissue (Skulan et al, 2007). Using a bed rest model, we demonstrate that the Ca isotope ratio of urine shifts in a direction consistent with bone loss after just 7 days of bed rest, long before detectable changes in bone mineral density (BMD) occur. The Ca isotope variations tracks changes observed in urinary N-teleopeptide, a bone resorption biomarker. Bone specific alkaline phosphatase, a bone formation biomarker, is unchanged. The established relationship between Ca isotopes and BMB can be used to quantitatively translate the changes in the Ca isotope ratio to changes in BMD using a simple mathematical model. This model predicts that subjects lost 0.25 0.07% ( SD) of their bone mass from day 7 to day 30 of bed rest. Given the rapid signal observed using Ca isotope measurements and the potential to quantitatively assess bone loss; this technique is well suited to study the short-term dynamics of bone metabolism.

Morgan, J. L. L.; Skulan, J. L.; Gordon, G. E.; Smith, Scott M.; Romaniello, S. J.; Anbar, A. D.

2012-01-01

270

Distinguishing sources of base cations in irrigated and natural soils: evidence from strontium isotopes  

Microsoft Academic Search

Strontium isotope ratios (87Sr\\/86Sr) of soil solids, soil cation extracts, irrigation water and plant material are used to determine strontium and therefore cation sources and fluxes in irrigated and natural soil–plant systems. Strontium isotopes of soil solids from four soil profiles (two irrigated vineyard soils and two 'natural' profiles from nearby reserves) show large differences between soil horizons with depth.

Graham P. Green; Erick A. Bestland; G. Stewart Walker

2004-01-01

271

Characterization of calcium isotopes in natural and synthetic barite  

USGS Publications Warehouse

The mineral barite (BaSO4) accommodates calcium in its crystal lattice, providing an archive of Ca-isotopes in the highly stable sulfate mineral. Holocene marine (pelagic) barite samples from the major ocean basins are isotopically indistinguishable from each other (??44/40Ca = -2.01 ?? 0.15???) but are different from hydrothermal and cold seep barite samples (??44/40Ca = -4.13 to -2.72???). Laboratory precipitated (synthetic) barite samples are more depleted in the heavy Ca-isotopes than pelagic marine barite and span a range of Ca-isotope compositions, ??44/40Ca = -3.42 to -2.40???. Temperature, saturation state, a Ba2 + / a SO42 -, and aCa2+/aBa2+ each influence the fractionation of Ca-isotopes in synthetic barite; however, the fractionation in marine barite samples is not strongly related to any measured environmental parameter. First-principles lattice dynamical modeling predicts that at equilibrium Ca-substituted barite will have much lower 44Ca/40Ca than calcite, by -9??? at 0 ??C and -8??? at 25 ??C. Based on this model, none of the measured barite samples appear to be in isotopic equilibrium with their parent solutions, although as predicted they do record lower ??44/40Ca values than seawater and calcite. Kinetic fractionation processes therefore most likely control the extent of isotopic fractionation exhibited in barite. Potential fractionation mechanisms include factors influencing Ca2+ substitution for Ba2+ in barite (e.g. ionic strength and trace element concentration of the solution, competing complexation reactions, precipitation or growth rate, temperature, pressure, and saturation state) as well as nucleation and crystal growth rates. These factors should be considered when investigating controls on isotopic fractionation of Ca2+ and other elements in inorganic and biogenic minerals. ?? 2008 Elsevier Ltd.

Griffith, E.M.; Schauble, E.A.; Bullen, T.D.; Paytan, A.

2008-01-01

272

Evaluation of the age of landfill gas methane in landfill gas-natural gas mixtures using co-occurring constituents.  

PubMed

At a municipal solid waste landfill in southern California (USA) overlying a natural gas reservoir, methane was detected at concentrations of up to 40% (by volume) in perimeter soil gas probes. Stable isotope and (14)C values of methane together with gas composition (major components and volatile organic compounds) data were evaluated to assess the relative contributions of landfill gas and natural gas to the measured methane concentrations. The data was further used to estimate the residence time of the landfill gas in the probes. Results showed that up to 37% of the measured methane was derived from landfill gas. In addition, the landfill gas in the probe samples has undergone extensive alteration due to dissolution of carbon dioxide in pore water. Data further indicates that the measured methane was released from the waste approximately 1.2 to 9.4 years ago, rather than representing evidence of an ongoing release. PMID:23660592

Kerfoot, Henry B; Hagedorn, Benjamin; Verwiel, Mark

2013-06-01

273

The nitrogen cycle in cryoconites: naturally occurring nitrification-denitrification granules on a glacier.  

PubMed

Cryoconites are microbial aggregates commonly found on glacier surfaces where they tend to take spherical, granular forms. While it has been postulated that the microbes in cryoconite granules play an important role in glacier ecosystems, information on their community structure is still limited, and their functions remain unclear. Here, we present evidence for the occurrence of nitrogen cycling in cryoconite granules on a glacier in Central Asia. We detected marker genes for nitrogen fixation, nitrification and denitrification in cryoconite granules by digital polymerase chain reaction (PCR), while digital reverse transcription PCR analysis revealed that only marker genes for nitrification and denitrification were abundantly transcribed. Analysis of isotope ratios also indicated the occurrence of nitrification; nitrate in the meltwater on the glacier surface was of biological origin, while nitrate in the snow was of atmospheric origin. The predominant nitrifiers on this glacier belonged to the order Nitrosomonadales, as suggested by amoA sequences and 16S ribosomal RNA pyrosequencing analysis. Our results suggest that the intense carbon and nitrogen cycles by nitrifiers, denitrifiers and cyanobacteria support abundant and active microbes on the Asian glacier. PMID:24946985

Segawa, Takahiro; Ishii, Satoshi; Ohte, Nobuhito; Akiyoshi, Ayumi; Yamada, Akinori; Maruyama, Fumito; Li, Zhongqin; Hongoh, Yuichi; Takeuchi, Nozomu

2014-10-01

274

Naturally occurring tetracycline-like fluorescence in sections of femur from jackals in Zimbabwe  

Microsoft Academic Search

In assessing the potential of the tetracycline compounds as biomarkers in oral rabies vaccination campaigns in jackals in Zimbabwe, the natural prevalence of fluorescent compounds in bone tissue from jackals was investigated. Femur samples were taken from unbaited jackals received for routine rabies diagnosis, and thin undecalcified sections were cut and viewed under an ultraviolet microscope. Of 131 femur samples

J Bingham; R Matema; A Kappeler; FW Hill

1994-01-01

275

Protoporphyrin IX Occurs Naturally in Colorectal Cancers and Their Metastases1  

Microsoft Academic Search

Colorectal cancers exhibit a red fluorescence. The nature of the respon- sible fluorophore and its eventual diagnostic potential were investigated. Thirty-three consecutive colorectal resection specimen, 32 of which with histologically confirmed cancer, and a total of 1053 palpable mesenteric nodes were fluorimetrically characterized ex vivo. Furthermore, frozen material from 28 patients was analyzed, selected for the availability of primary tumor

K. Thomas Moesta; Bernd Ebert; Tim Handke; Dirk Nolte; Christian Nowak; Wolfgang E. Haensch; Ravindra K. Pandey; Thomas J. Dougherty; Herbert Rinneberg; Peter M. Schlag

276

A NATURALLY OCCURRING EPIGENETIC MUTATION IN AN SBP-BOX GENE INHIBITS TOMATO FRUIT RIPENING  

Technology Transfer Automated Retrieval System (TEKTRAN)

A major player in the regulatory network controlling fruit ripening is likely to be the gene at the tomato Colorless non-ripening (Cnr) locus 1,2. The Cnr mutation results in colorless fruits with a significant loss of cell to cell adhesion. The nature of the mutation and the identity of the Cnr g...

277

Naturally occurring scrapie is associated with a lower CBG binding capacity in ewes  

Microsoft Academic Search

Naturally scrapie-affected ewes present a syndrome of hypercortisolism as evaluated by measuring total plasma cortisol concentrations. The objective of this study was to investigate the plasma protein binding of cortisol and to evaluate the concentration of the biologically active free fraction of cortisol in scrapie-affected ewes. Corticosteroid binding globulin (CBG) binding parameters were evalu- ated by equilibrium dialysis in 13

N Picard-Hagen; V Gayrard; M Alvinerie; V Laroute; C Touron; O Andreoletti; P L Toutain

2000-01-01

278

NATURAL OCCURANCE OF XYLELLA FASTIDIOSA IN A COMMERCIAL NURSERY IN MARYLAND  

Technology Transfer Automated Retrieval System (TEKTRAN)

Since Xylella fastidiosa is an important plant pathogen in the landscape nursery trade, a survey was conducted in 2003 and 2004 in a commercial wholesale and production nursery in Maryland to determine the natural occurrence of X. fastidiosa in nursery plants and surrounding vegetation using enzyme-...

279

Directed Evolution Natural evolution: Over time, random genetic mutations occur within an  

E-print Network

the parents ­ selection: survival of the fittest ­ amplification: procreation #12;2 Benefits of directed to survival Directed evolution mimics natural evolution in the laboratory (in vitro), but operates is compensated for by use of a powerful selection/screening method based on the concept of the survival

Park, Sheldon

280

Rapidly Assessing Changes in Bone Mineral Balance Using Natural Stable Calcium Isotopes  

NASA Technical Reports Server (NTRS)

We demonstrate that variations in the Ca isotope ratios in urine rapidly and quantitatively reflect changes in bone mineral balance. This variation occurs because bone formation depletes soft tissue of light Ca isotopes, while bone resorption releases that isotopically light Ca back into soft tissue. In a study of 12 individuals confined to bed rest, a condition known to induce bone resorption, we show that Ca isotope ratios shift in a direction consistent with net bone loss after just 7 days, long before detectible changes in bone density occur. Consistent with this interpretation, the Ca isotope variations track changes observed in N-teleopeptide, a bone resorption biomarker, while bone-specific alkaline phosphatase, a bone formation biomarker, is unchanged. Ca isotopes can in principle be used to quantify net changes in bone mass. Ca isotopes indicate an average loss of 0.62 +/- 0.16 % in bone mass over the course of this 30-day study. The Ca isotope technique should accelerate the pace of discovery of new treatments for bone disease and provide novel insights into the dynamics of bone metabolism.

Morgan, J. L. L.; Gordon, G. W.; Romaniello, S. J.; Skulan, J. L.; Smith, S. M.; Anbar, A. D.

2011-01-01

281

Naturally occurring asbestos in eastern Australia: a review of geological occurrence, disturbance and mesothelioma risk  

Microsoft Academic Search

Potential asbestos-bearing rocks account for about 0.2% of the land area of eastern Australia. The main mode of occurrence\\u000a is as narrow cross fibre and slip fibre veins of chrysotile asbestos in serpentinised ophiolite complexes along the boundaries\\u000a of major tectonic domains. Smaller deposits of chrysotile and amphibole asbestos occur in metamorphosed mafic and ultramafic\\u000a rocks associated with the Macquarie

Marc Hendrickx

2009-01-01

282

Stratigraphic and geochemical controls on naturally occurring arsenic in groundwater, eastern Wisconsin, USA  

Microsoft Academic Search

High arsenic concentrations (up to 12,000 7g\\/L) have been measured in groundwater from a confined sandstone aquifer in eastern Wisconsin. The main arsenic source is a sulfide-bearing secondary cement horizon (SCH) that has variable thickness, morphology, and arsenic concentrations. Arsenic occurs in pyrite and marcasite as well as in iron oxyhydroxides but not as a separate arsenopyrite phase. Nearly identical

M. E. Schreiber; J. A. Simo; P. G. Freiberg

2000-01-01

283

The isotopic effects of electron transfer: An explanation for Fe isotope fractionation in nature  

Microsoft Academic Search

Isotope fractionation of electroplated Fe was measured as a function of applied electrochemical potential. As plating voltage was varied from ?0.9 V to 2.0 V, the isotopic signature of the electroplated iron became depleted in heavy Fe, with ?56Fe values (relative to IRMM-14) ranging from ?0.18(±0.02) to ?2.290(±0.006) ‰, and corresponding ?57Fe values of ?0.247(±0.014) and ?3.354(±0.019) ‰. This study

Abby Kavner; François Bonet; Anat Shahar; Justin Simon; Edward Young

2005-01-01

284

Estimation of the radiological background and dose assessment in areas with naturally occurring uranium geochemical anomalies--a case study in the Iberian Massif (Central Portugal).  

PubMed

Naturally occurring uranium geochemical anomalies, representative of the several thousand recognized in the Portuguese section of the Iberian Massif and outcropping in three target areas with a total of a few thousand square metres, were subjected to a detailed study (1:1000 scale) to evaluate the radiological health-risk on the basis of a dose assessment. To reach this goal some radioactive isotopes from the uranium, thorium and potassium radioactive series were measured in 52 samples taken from different environmental compartments: soils, stream sediments, water, foodstuff (vegetables) and air; external radiation was also measured through a square grid of 10×10 m, with a total of 336 measurements. The results show that some radioisotopes have high activities in all the environmental compartments as well as a large variability, namely for those of the uranium decay chain, which is a common situation in the regional geological setting. Isotopic disequilibrium is also common and led to an enrichment of several isotopes in the different pathways, as is the case of (226)Ra; maximum values of 1.76 Bq L(-1) (water), 986 Bq kg(-1) (soils) and 18.9 Bq kg(-1) (in a turnip sample) were measured. On the basis of a realistic scenario combined with the experimental data, the effective dose from exposure to ionizing radiation for two groups of the population (rural and urban) was calculated; the effective dose is variable between 8.0 and 9.5 mSv year(-1), which is 3-4 times higher than the world average. Thus, the radiological health-risk for these populations could be significant and the studied uranium anomalies must be taken into account in the assessment of the geochemical background. The estimated effective dose can also be used as typical of the background of the Beiras uranium metalogenetic province and therefore as a "benchmark" in the remediation of the old uranium mining sites. PMID:22694913

Pereira, A J S C; Neves, L J P F

2012-10-01

285

Naturally occurring radioactive materials (NORMs) generated from lignite-fired power plants in Kosovo.  

PubMed

The energy production in Kosovo depends primarily on lignite-fired power plants. During coal combustion, huge amounts of fly ash and bottom ash are generated, which may result in enriched natural radionuclides; therefore, these radionuclides need to be investigated to identify the possible processes that may lead to the radiological exposure of workers and the local population. Lignite samples and NORMs of fly ash and bottom ash generated in lignite-fired power plants in Kosovo are analyzed using a gamma-ray spectrometry method for the activity concentration of natural radionuclides. The average activity concentrations of (40)K, (226)Ra and (232)Th in lignite are found to be 36 ± 8 Bq kg(-1), 9 ± 1 Bq kg(-1) and 9 ± 3 Bq kg(-1), respectively. Indications on the occurrence and geochemical behavior of uranium in the lignite matrix are suggested. The activity concentrations of natural radionuclides in fly ash and bottom ash samples are found to be concentrated from 3 to 5 times that of the feeding lignite. The external gamma-ray absorbed dose rate and the activity concentration index are calculated to assess the radiological hazard arising from ash disposal and recycling in the cement industry. PMID:25233215

Hasani, F; Shala, F; Xhixha, G; Xhixha, M K; Hodolli, G; Kadiri, S; Bylyku, E; Cfarku, F

2014-12-01

286

Mapping Relative Likelihood for the Presence of Naturally Occurring Asbestos in Placer and Eastern Sacramento Counties, California  

Microsoft Academic Search

Naturally occurring asbestos (NOA) is a term applied to the geologic occurrence of six types of silicate minerals that have asbestiform habit. These include the serpentine mineral chrysotile and the amphibole minerals actinolite, amosite, anthophyllite, crocidolite, and tremolite; all are classified as known human carcinogens. NOA, which is likely to be present in at least 50 of the 58 counties

C. T. Higgins; J. P. Clinkenbeard; R. K. Churchill

2006-01-01

287

Isolation and identification of a new, naturally occurring cytokinin (6-benzylaminopurineriboside) from an anise cell culture ( Pimpinella anisum L.)  

Microsoft Academic Search

A new, naturally occurring cytokinin was isolated from a cell culture of anise (Pimpinella anisum L.). Its structure was determined as 6-benzylaminopurine riboside by the use of gas chromatography and mass spectrometry. Quantitation of this new plant hormone was accomplished by single-ion-monitoring measurements.

D. Ernst; W. Schäfer; D. Oesterhelt

1983-01-01

288

Lab 2: Mineral Lab notes. Minerals are inorganic, solid, naturally occurring substances that have a characteristic chemical compositions,  

E-print Network

Lab 2: Mineral Lab notes. Minerals are inorganic, solid, naturally occurring substances that have composition is the chemical elements that make up any given mineral. For instance, the mineral quartz is silicon dioxide SiO2; the mineral galena is an ore of lead, and its chemical formula is PbS, a lead

Li, X. Rong

289

Recruiting Older Adults into a Physical Activity Promotion Program: "Active Living Every Day" Offered in a Naturally Occurring Retirement Community  

ERIC Educational Resources Information Center

Purpose: This article explores recruitment strategies based on the transtheoretical model (TTM) with older adults living in a naturally occurring retirement community (NORC) to encourage enrollment in a physical activity promotion program, "Active Living Every Day" (ALED). Reasons for participation or nonparticipation are identified. Design and…

Hildebrand, Mary; Neufeld, Peggy

2009-01-01

290

Inorganic arsenic (InAs) occurs naturally in the groundwater of many parts of the world, and  

E-print Network

Inorganic arsenic (InAs) occurs naturally in the groundwater of many parts of the world 2002). Ingested arsenic causes cancers of the skin, bladder, and lung and has been associated that are about 30­3,000 times lower (Smith et al. 2002). Importantly, the new U.S. standard for arsenic applies

California at Berkeley, University of

291

Evaluation of the Fate of Naturally Occurring Escherichia coli O157:H7 During Bovine Manure Composting Processes  

Technology Transfer Automated Retrieval System (TEKTRAN)

Foodborne illnesses associated with produce consumption have brought attention to livestock manure composts as potential sources of pathogens for the contamination of these crops. Our objective was to determine the fate of naturally-occurring E. coli O157:H7 during “minimally managed” on-farm bovin...

292

Elevated Appraisals of the Negative Impact of Naturally Occurring Life Events: A Risk Factor for Depressive and Anxiety Disorders  

ERIC Educational Resources Information Center

The tendency to appraise naturally occurring life events (LEs) as having high negative impact may be a predisposing factor for the development of depression and anxiety disorders. In the current study, appraisals of the negative impact of recent LEs were examined in relationship to depressive and anxiety disorders in a sample of 653 adolescents…

Espejo, Emmanuel Peter; Hammen, Constance; Brennan, Patricia A.

2012-01-01

293

Healthy Naturally Occurring Retirement Communities: The Need for Increased Collaboration Between Local Public Health Agencies and Municipal Government  

Microsoft Academic Search

Naturally occurring retirement communities (NORCs) exist on a “health promoting” continuum in the extent to which they facilitate healthy aging. Some NORCs are healthier than others for seniors because their physical and social environments encourage activity and promote feelings of well-being. Municipal governments and public health agencies have different potential roles in developing healthy-NORCs. Municipal government responsibilities affect housing, transportation,

Paul J. Masotti; Robert Fick; Kathleen O’Connor

2010-01-01

294

Interactions between natural-occurring landscape conditions and land use influencing the abundance of riverine smallmouth bass, micropterus dolomieu  

USGS Publications Warehouse

This study examined how interactions between natural landscape features and land use influenced the abundance of smallmouth bass, Micropterus dolomieu, in Missouri, USA, streams. Stream segments were placed into one of four groups based on natural-occurring watershed characteristics (soil texture and soil permeability) predicted to relate to smallmouth bass abundance. Within each group, stream segments were assigned forest (n = 3), pasture (n = 3), or urban (n = 3) designations based on the percentages of land use within each watershed. Analyses of variance indicated smallmouth bass densities differed between land use and natural conditions. Decision tree models indicated abundance was highest in forested stream segments and lowest in urban stream segments, regardless of group designation. Land use explained the most variation in decision tree models, but in-channel features of temperature, flow, and sediment also contributed significantly. These results are unique and indicate the importance of natural-occurring watershed conditions in defining the potential of populations and how finer-scale filters interact with land use to further alter population potential. Smallmouth bass has differing vulnerabilities to land-use attributes, and the better the natural watershed conditions are for population success, the more resilient these populations will be when land conversion occurs.

Brewer, S.K.; Rabeni, C.F.

2011-01-01

295

ISOTOPE HYDROLOGY LABORATORY (WATER QUALITY MANAGEMENT BRANCH, WATER SUPPLY AND WATER RESOURCES DIVISION, NRMRL)  

EPA Science Inventory

The mission of NRMRL's Water Supply and Water Resources Division's Isotope Hydrology Laboratory (IHL) is to resolve environmental hydrology problems through research and application of naturally occurring isotopes. The emergent field of isotope hydrology follows advances in anal...

296

ANALYTICAL CAPABILITY - ISOTOPE HYDROLOGY LABORATORY (WATER QUALITY MANAGEMENT BRANCH, WATER SUPPLY AND WATER RESOURCES DIVISION, NRMRL)  

EPA Science Inventory

The mission of NRMRL's Water Supply and Water Resources Division's Isotope Hydrology Laboratory is to resolve environmental hydrology problems through research and application of naturally occurring isotopes. Analytical capabilities at IHL include light stable isotope radio mass...

297

Genetic background and GxE interactions modulate the penetrance of a naturally occurring wing mutation in Drosophila melanogaster.  

PubMed

Many genes involved in producing complex traits are incompletely penetrant. One such example is vesiculated, an X-linked gene in Drosophila melanogaster that results in wing defects. To examine the genetic architecture of a complex trait (wings containing vesicles), we placed a naturally occurring variant into multiple autosomal backgrounds and quantified penetrance and expressivity at a range of developmental temperatures. We found significant epistasis, genotype-by-environment interactions, and maternal effects. Sex and temperature effects were modulated by genetic background. The severity of wing phenotypes also varied across different genetic backgrounds, and expressivity was positively correlated with penetrance. We also found evidence of naturally segregating suppressors of vesiculated. These suppressors were present on both the second and third chromosomes, and complex interactions were observed. Taken together, these findings indicate that multiple genetic and environmental factors modulate the phenotypic effects of a naturally occurring vesiculated allele. PMID:24002866

Lachance, Joseph; Jung, Lawrence; True, John R

2013-11-01

298

Genetic variation for an aphid wing polyphenism is genetically linked to a naturally occurring wing polymorphism  

PubMed Central

Many polyphenisms are examples of adaptive phenotypic plasticity where a single genotype produces distinct phenotypes in response to environmental cues. Such alternative phenotypes occur as winged and wingless parthenogenetic females in the pea aphid (Acyrthosiphon pisum). However, the proportion of winged females produced in response to a given environmental cue varies between clonal genotypes. Winged and wingless phenotypes also occur in males of the sexual generation. In contrast to parthenogenetic females, wing production in males is environmentally insensitive and controlled by the sex-linked, biallelic locus, aphicarus (api). Hence, environmental or genetic cues induce development of winged and wingless phenotypes at different stages of the pea aphid life cycle. We have tested whether allelic variation at the api locus explains genetic variation in the propensity to produce winged females. We assayed clones from an F2 cross that were heterozygous or homozygous for alternative api alleles for their propensity to produce winged offspring. We found that clones with different api genotypes differed in their propensity to produce winged offspring. The results indicate genetic linkage of factors controlling the female wing polyphenism and male wing polymorphism. This finding is consistent with the hypothesis that genotype by environment interaction at the api locus explains genetic variation in the environmentally cued wing polyphenism. PMID:15817441

Braendle, Christian; Friebe, Ilvy; Caillaud, Marina C; Stern, David L

2005-01-01

299

Naturally occurring tetracycline-like fluorescence in sections of femur from jackals in Zimbabwe.  

PubMed

In assessing the potential of the tetracycline compounds as biomarkers in oral rabies vaccination campaigns in jackals in Zimbabwe, the natural prevalence of fluorescent compounds in bone tissue from jackals was investigated. Femur samples were taken from unbaited jackals received for routine rabies diagnosis, and thin undecalcified sections were cut and viewed under an ultraviolet microscope. Of 131 femur samples examined, 49 (37 per cent) had fluorescent markings indistinguishable from those of tetracycline. The result implies that the tetracycline compounds, which are commonly used in rabies baiting campaigns in Europe and North America, cannot be used as biomarkers in jackals in Zimbabwe. PMID:7992475

Bingham, J; Matema, R; Kappeler, A; Hill, F W

1994-08-20

300

Naturally occurring plant isoquinoline N-oxide alkaloids: their pharmacological and SAR activities.  

PubMed

The present review describes research on novel natural isoquinoline alkaloids and their N-oxides isolated from different plant species. More than 200 biological active compounds have shown confirmed antimicrobial, antibacterial, antitumor, and other activities. The structures, origins, and reported biological activities of a selection of isoquinoline N-oxides alkaloids are reviewed. With the computer program PASS some additional SAR (structure-activity relationship) activities are also predicted, which point toward new possible applications of these compounds. This review emphasizes the role of isoquinoline N-oxides alkaloids as an important source of leads for drug discovery. PMID:25636889

Dembitsky, Valery M; Gloriozova, Tatyana A; Poroikov, Vladimir V

2015-01-15

301

The naturally occurring carcinogen ptaquiloside is present in groundwater below bracken vegetation.  

PubMed

The present study demonstrates unequivocally the presence of the natural carcinogen ptaquiloside and its transformation product pterosin B in groundwater and surface water. Groundwater concentrations up to 0.23 nmol/L (92?ng/L) ptaquiloside and up to 2.2 nmol/L (0.47?µg/L) pterosin B were found. Of 21 groundwater samples, 5 contained ptaquiloside, exceeding the estimated threshold for drinking water (1.3-40?pmol/L). The results are critical for water abstraction in bracken-infested areas. PMID:24464773

Clauson-Kaas, Frederik; Jensen, Pia H; Jacobsen, Ole S; Juhler, René K; Hansen, Hans Christian B

2014-05-01

302

Shortcut Syntheses of Naturally Occurring 5-Alkylresorcinols with DNA-Cleaving Properties.  

PubMed

Resorcinols such as 1-5 bearing long alkyl- or alkenyl substituents at the C-5 position, including bola-formed bis-resorcinol derivatives, have recently been isolated from natural sources and were shown to exhibit exceptional DNA-cleaving properties under oxidative conditions. Previous synthetic approaches to such compounds seem inappropriately lengthy with regard to their structural simplicity. Disclosed is a very flexible synthesis which assembles these targets from triflate 7 and well accessible alkenes, dienes, enynes, or dienynes, respectively, by means of a boron-mediated reaction manifold. As a typical example, hexadeca-1,15-dien-8-yne 11 is hydroborated with 9-H-9-BBN at all possible sites, the alkenyl borane entity of the resulting tris-borane 12 is selectively cleaved off to afford the desired (Z)-alkene group in a stereoselective manner, the remaining two terminal alkylboranes are treated with NaOMe, and the bis-borate complex 13 thus formed is finally used as the nucleophile for a palladium-catalyzed Suzuki cross-coupling reaction with triflate 7. This sequence is carried out in one pot and provides product 14 in 62% overall yield. Demethylation of 14 (and analogues) can be conveniently achieved by means of 9-iodo-9-BBN to afford the natural product 5. The efficiency and flexibility of this unprecedented approach which combines different features of classical and modern boron chemistry is further demonstrated by the synthesis of anacardic and ginkgolic acid derivatives. PMID:11671563

Fürstner, Alois; Seidel, Günter

1997-04-18

303

Naturally occurring bacteraemia in American lobsters, Homarus americanus Milne-Edwards, in Long Island Sound.  

PubMed

The health status of the American lobster, Homarus americanus Milne-Edwards, in Long Island Sound (LIS) has been in decline, with seasonal mortality events occurring since 1998. In order to assess the potential effects of environmental conditions on lobster health via haemolymph analysis, lobsters collected from various sites in LIS were examined and sampled while concurrent environmental data (water temperature, salinity and dissolved oxygen) were recorded. The pH of the haemolymph of each lobster was tested, followed by a collection of haemolymph for serum biochemistry analysis and bacterial culture. This report focuses on the results of the bacterial sampling. The majority of bacteria cultured were opportunistic pathogens commonly found in the environment, including some that are associated with sewage and pollution. The prevalence of bacteraemia was correlated with the site of collection, the month in which the lobsters were sampled, and water temperature. PMID:18086031

Bartlett, S L; Wooster, G A; Sokolowski, M S; Dove, A D M; Bowser, P R

2008-01-01

304

Sequestering carbon dioxide into complex structures of naturally occurring gas hydrates  

PubMed Central

Large amounts of CH4 in the form of solid hydrates are stored on continental margins and in permafrost regions. If these CH4 hydrates could be converted into CO2 hydrates, they would serve double duty as CH4 sources and CO2 storage sites. We explore here the swapping phenomenon occurring in structure I (sI) and structure II (sII) CH4 hydrate deposits through spectroscopic analyses and its potential application to CO2 sequestration at the preliminary phase. The present 85% CH4 recovery rate in sI CH4 hydrate achieved by the direct use of binary N2 + CO2 guests is surprising when compared with the rate of 64% for a pure CO2 guest attained in the previous approach. The direct use of a mixture of N2 + CO2 eliminates the requirement of a CO2 separation/purification process. In addition, the simultaneously occurring dual mechanism of CO2 sequestration and CH4 recovery is expected to provide the physicochemical background required for developing a promising large-scale approach with economic feasibility. In the case of sII CH4 hydrates, we observe a spontaneous structure transition of sII to sI during the replacement and a cage-specific distribution of guest molecules. A significant change of the lattice dimension caused by structure transformation induces a relative number of small cage sites to reduce, resulting in the considerable increase of CH4 recovery rate. The mutually interactive pattern of targeted guest–cage conjugates possesses important implications for the diverse hydrate-based inclusion phenomena as illustrated in the swapping process between CO2 stream and complex CH4 hydrate structure. PMID:16908854

Park, Youngjune; Kim, Do-Youn; Lee, Jong-Won; Huh, Dae-Gee; Park, Keun-Pil; Lee, Jaehyoung; Lee, Huen

2006-01-01

305

Elevated naturally occurring arsenic in a semiarid oxidizing system, Southern High Plains aquifer, Texas, USA  

USGS Publications Warehouse

High groundwater As concentrations in oxidizing systems are generally associated with As adsorption onto hydrous metal (Al, Fe or Mn) oxides and mobilization with increased pH. The objective of this study was to evaluate the distribution, sources and mobilization mechanisms of As in the Southern High Plains (SHP) aquifer, Texas, relative to those in other semiarid, oxidizing systems. Elevated groundwater As levels are widespread in the southern part of the SHP (SHP-S) aquifer, with 47% of wells exceeding the current EPA maximum contaminant level (MCL) of 10 ??g/L (range 0.3-164 ??g/L), whereas As levels are much lower in the north (SHP-N: 9% ??? As MCL of 10 ??g/L; range 0.2-43 ??g/L). The sharp contrast in As levels between the north and south coincides with a change in total dissolved solids (TDS) from 395 mg/L (median north) to 885 mg/L (median south). Arsenic is present as arsenate (As V) in this oxidizing system and is correlated with groundwater TDS (Spearman's ?? = 0.57). The most likely current source of As is sorbed As onto hydrous metal oxides based on correlations between As and other oxyanion-forming elements (V, ?? = 0.88; Se, ?? = 0.54; B, ?? = 0.51 and Mo, ?? = 0.46). This source is similar to that in other oxidizing systems and constitutes a secondary source; the most likely primary source being volcanic ashes in the SHP aquifer or original source rocks in the Rockies, based on co-occurrence of As and F (?? = 0.56), oxyanion-forming elements and SiO2 (?? = 0.41), which are found in volcanic ashes. High groundwater As concentrations in some semiarid oxidizing systems are related to high evaporation. Although correlation of As with TDS in the SHP aquifer may suggest evaporative concentration, unenriched stable isotopes (??2H: -65 to -27; ??18O: -9.1 to -4.2) in the SHP aquifer do not support evaporation. High TDS in the SHP aquifer is most likely related to upward movement of saline water from the underlying Triassic Dockum aquifer. Mobilization of As in other semiarid oxidizing systems is caused by increased pH; however, pH in the SHP aquifer is near neutral (10-90 percentiles, 7.0-7.6). Although many processes, such as competitive desorption with SiO2, VO4, or PO4, could be responsible for local mobilization of As in the SHP aquifer, the most plausible explanation for the regional As distribution and correlation with TDS is the counterion effect caused by a change from Ca- to Na-rich, water as shown by the high correlation between As and Na/(Ca)0.5 ratios (?? = 0.57). This change in chemistry is related to mixing with saline water that moves upward from the underlying Dockum aquifer. This counterion effect may mobilize other anions and oxyanion-forming elements that are correlated with As (F, V, Se, B, Mo and SiO2). Competition among the oxyanions for sorption sites may enhance As mobilization. The SHP case study has similar As sources to those of other semiarid, oxidizing systems (original volcanic ash source followed by sorption onto hydrous metal oxides) but contrasts with these systems by showing lack of evaporative concentration and pH mobilization of As but counterion mobilization of As instead in the SHP-S aquifer. ?? 2009 Elsevier Ltd.

Scanlon, B.R.; Nicot, J.-P.; Reedy, R.C.; Kurtzman, D.; Mukherjee, A.; Nordstrom, D.K.

2009-01-01

306

Schwann cell hyperplasia and tumors in transgenic mice expressing a naturally occurring mutant NF2 protein  

PubMed Central

Specific mutations in some tumor suppressor genes such as p53 can act in a dominant fashion. We tested whether this mechanism may also apply for the neurofibromatosis type-2 gene (NF2) which, when mutated, leads to schwannoma development. Transgenic mice were generated that express, in Schwann cells, mutant NF2 proteins prototypic of natural mutants observed in humans. Mice expressing a NF2 protein with an interstitial deletion in the amino-terminal domain showed high prevalence of Schwann cell-derived tumors and Schwann cell hyperplasia, whereas those expressing a carboxy-terminally truncated protein were normal. Our results indicate that a subset of mutant NF2 alleles observed in patients may encode products with dominant properties when overexpressed in specific cell lineages. PMID:10215625

Giovannini, Marco; Robanus-Maandag, Els; Niwa-Kawakita, Michiko; van der Valk, Martin; Woodruff, James M.; Goutebroze, Laurence; Mérel, Philippe; Berns, Anton; Thomas, Gilles

1999-01-01

307

Genetic architecture of naturally occurring quantitative traits in plants: an updated synthesis.  

PubMed

Deciphering the genetic and molecular bases of quantitative variation is a long-standing challenge in plant biology because it is essential for understanding evolution and for accelerating plant breeding. Recent multi-trait analyses at different phenotypic levels are uncovering the pleiotropy and the genetic regulation underlying high-level complex traits. Thus, the number of known causal loci, genes and nucleotide polymorphisms is expanding. Current plant causal catalogs contain ?400 genes and natural polymorphisms revealing several dysfunctional allelic series that involve multiple mutations. In addition, repeated evolution of quantitative traits mediated by large effect alleles is found across plant phylogeny. Finally, systematic analyses of genetic and environmental interactions are beginning to elucidate the molecular mechanisms of relevant interactions. PMID:24565952

Alonso-Blanco, Carlos; Méndez-Vigo, Belén

2014-04-01

308

Wedelolactone, a Naturally Occurring Coumestan, Enhances Interferon-? Signaling through Inhibiting STAT1 Protein Dephosphorylation*  

PubMed Central

Signal transducers and activators of transcription 1 (STAT1) transduces signals from cytokines and growth factors, particularly IFN-?, and regulates expression of genes involved in cell survival/death, proliferation, and migration. STAT1 is activated through phosphorylation on its tyrosine 701 by JAKs and is inactivated through dephosphorylation by tyrosine phosphatases. We discovered a natural compound, wedelolactone, that increased IFN-? signaling by inhibiting STAT1 dephosphorylation and prolonging STAT1 activation through specific inhibition of T-cell protein tyrosine phosphatase (TCPTP), an important tyrosine phosphatase for STAT1 dephosphorylation. More interestingly, wedelolactone inhibited TCPTP through interaction with the C-terminal autoinhibition domain of TCPTP. We also found that wedelolactone synergized with IFN-? to induce apoptosis of tumor cells. Our data suggest a new target for anticancer or antiproliferation drugs, a new mechanism to regulate PTPs specifically, and a new drug candidate for treating cancer or other proliferation disorders. PMID:23580655

Chen, Zhimin; Sun, Xiaoxiao; Shen, Shensi; Zhang, Haohao; Ma, Xiuquan; Liu, Jingli; Kuang, Shan; Yu, Qiang

2013-01-01

309

Naturally occurring plant polyphenols as potential therapies for inherited neuromuscular diseases.  

PubMed

There are several lines of laboratory-based evidence emerging to suggest that purified polyphenol compounds such as resveratrol, found naturally in red grapes, epigallocatechin galate from green tea and curcumin from turmeric, might be useful for the treatment of various inherited neuromuscular diseases, including spinal muscular atrophy, Duchenne muscular dystrophy and Charcot-Marie-Tooth disease. Here, we critically examine the scientific evidence related to the known molecular effects that these polyphenols have on different models of inherited neuromuscular disease, with particular attention to problems with the validity of in vitro evidence. We also present proteomic evidence that polyphenols have in vitro effects on cells related to metal ion chelation in cell-culture media. Although their precise mechanisms of action remain somewhat elusive, polyphenols could be an attractive approach to therapy for inherited neuromuscular disease, especially since they may be safer to use on young children, compared with some of the other drug candidates. PMID:24215348

Fuller, Heidi R; Humphrey, Emma L; Morris, Glenn E

2013-11-01

310

Solid-state NMR in the analysis of drugs and naturally occurring materials.  

PubMed

This article presents some of the solid-state NMR (SSNMR) techniques used in the pharmaceutical and biomedical research. Solid-state magic angle spinning (MAS) NMR provides structural information on powder amorphous solids for which single-crystal diffraction structures cannot be obtained. NMR is non-destructive; the powder sample may be used for further studies. Quantitative results can be obtained, although solid-state NMR spectra are not normally quantitative. As compared with other techniques, MAS NMR is insensitive and requires a significant amount of the powder sample (2-100mg) to fill the 1.3-7 mm ZrO2 rotor. This is its main drawback, since natural compounds isolated from plants, microorganisms or cell cultures are difficult to obtain in quantities higher than a few milligrams. Multinuclear MAS NMR routinely uses (1)H and (13)C nuclei, less frequently (15)N, (19)F, (31)P, (77)Se, (29)Si, (43)Ca or (23)Na. The article focuses on the pharmaceutical applications of SSNMR, the studies were aimed to control over manufacturing processes (e.g. crystallization and milling) investigation of chemical and physical stability of solid forms both as pure drug and in a formulated product. SSNMR is used in combination with some other analytical methods (DSC, XRD, FT-IR) and theoretical calculations of NMR parameters. Biologically active compounds, such as amino acids and small peptides, steroids and flavonoids were studied by SSNMR methods (part 4) providing valuable structural information. The SSNMR experiments performed on biopolymers and large natural products like proteins, cellulose and lipid layers are commented upon briefly in part 5. PMID:24173236

Paradowska, Katarzyna; Wawer, Iwona

2014-05-01

311

Diagnostic features in 10 naturally occurring cases of acute fatal canine leptospirosis.  

PubMed

The current report describes the diagnostic features in 10 cases of acute fatal canine leptospirosis with minimal renal and hepatic changes that may present a diagnostic challenge for the pathologist. Most affected dogs were less than 6 months of age and had a biochemical profile consistent with hepatorenal dysfunction. Clinical signs consisted of vomiting, depression, icterus, dehydration, diarrhea, and anorexia. All dogs died or were humanely euthanized within 3-7 days after the onset of clinical disease. Necropsy findings included pulmonary edema with hemorrhages, icterus, renal and hepatic pallor and swelling, and gastric edema with hemorrhage. Despite severe azotemia, histological changes in the kidneys were subtle in all dogs, and included mild renal tubular simplification, with single-cell necrosis and attenuation, along with minimal interstitial lymphoplasmacytic inflammation, edema, and hemorrhage. Hepatic lesions included scattered hepatocellular single-cell necrosis and hepatocellular dissociation. Prominent extrarenal lesions typically associated with uremia including vascular fibrinoid necrosis in multiple organs, pulmonary mineralization with occasional fibrinosuppurative exudation, and gastric mineralization were also present. Postmortem diagnostic confirmation was based on the detection of leptospiral antigen on fresh renal samples by fluorescent antibody test and on the demonstration of intact spirochetes in sections of kidneys using immunohistochemical staining. Acute fatal canine leptospirosis occurred as a fulminant hepatorenal disease affecting mainly young dogs, and the diagnosis was dependent on the recognition of the subtle renal changes with confirmation via fluorescent antibody testing or immunohistochemical staining. PMID:25274745

Rissi, Daniel R; Brown, Cathy A

2014-11-01

312

Phylogeny and virulence of naturally occurring type III secretion system-deficient Pectobacterium strains.  

PubMed

Pectobacterium species are enterobacterial plant-pathogenic bacteria that cause soft rot disease in diverse plant species. Previous epidemiological studies of Pectobacterium species have suffered from an inability to identify most isolates to the species or subspecies level. We used three previously described DNA-based methods, 16S-23S intergenic transcribed spacer PCR-restriction fragment length polymorphism analysis, multilocus sequence analysis (MLSA), and pulsed-field gel electrophoresis, to examine isolates from diseased stems and tubers and found that MLSA provided the most reliable classification of isolates. We found that strains belonging to at least two Pectobacterium clades were present in each field examined, although representatives of only three of five Pectobacterium clades were isolated. Hypersensitive response and DNA hybridization assays revealed that strains of both Pectobacterium carotovorum and Pectobacterium wasabiae lack a type III secretion system (T3SS). Two of the T3SS-deficient strains assayed lack genes adjacent to the T3SS gene cluster, suggesting that multiple deletions occurred in Pectobacterium strains in this locus, and all strains appear to have only six rRNA operons instead of the seven operons typically found in Pectobacterium strains. The virulence of most of the T3SS-deficient strains was similar to that of T3SS-encoding strains in stems and tubers. PMID:19411432

Kim, Hye-Sook; Ma, Bing; Perna, Nicole T; Charkowski, Amy O

2009-07-01

313

Sulphoraphane, a naturally occurring isothiocyanate induces apoptosis in breast cancer cells by targeting heat shock proteins  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer HSPs (27, 70 and 90) and HSF1 are overexpressed in MCF-7 and MDA-MB-231 cells. Black-Right-Pointing-Pointer Sulphoraphane, a natural isothiocyanate inhibited HSPs and HSF1 expressions. Black-Right-Pointing-Pointer Inhibition of HSPs and HSF1 lead to regulation of apoptotic proteins. Black-Right-Pointing-Pointer Alteration of apoptotic proteins activate of caspases particularly caspase 3 and 9 leading to induction of apoptosis. Black-Right-Pointing-Pointer Alteration of apoptotic proteins induce caspases leading to induction of apoptosis. -- Abstract: Heat shock proteins (HSPs) are involved in protein folding, aggregation, transport and/or stabilization by acting as a molecular chaperone, leading to inhibition of apoptosis by both caspase dependent and/or independent pathways. HSPs are overexpressed in a wide range of human cancers and are implicated in tumor cell proliferation, differentiation, invasion and metastasis. HSPs particularly 27, 70, 90 and the transcription factor heat shock factor1 (HSF1) play key roles in the etiology of breast cancer and can be considered as potential therapeutic target. The present study was designed to investigate the role of sulphoraphane, a natural isothiocyanate on HSPs (27, 70, 90) and HSF1 in two different breast cancer cell lines MCF-7 and MDA-MB-231 cells expressing wild type and mutated p53 respectively, vis-a-vis in normal breast epithelial cell line MCF-12F. It was furthermore investigated whether modulation of HSPs and HSF1 could induce apoptosis in these cells by altering the expressions of p53, p21 and some apoptotic proteins like Bcl-2, Bax, Bid, Bad, Apaf-1 and AIF. Sulphoraphane was found to down-regulate the expressions of HSP70, 90 and HSF1, though the effect on HSP27 was not pronounced. Consequences of HSP inhibition was upregulation of p21 irrespective of p53 status. Bax, Bad, Apaf-1, AIF were upregulated followed by down-regulation of Bcl-2 and this effect was prominent in MCF-7 than in MDA-MB-231. However, very little change in the expression of Bid was observed. Alteration in Bcl-2 Bax ratio resulted in the release of cytochrome c from mitochondria and activation of caspases 3 and 9 which are in agreement with apoptotic index values. Sulphoraphane therefore can be regarded as a potent inducer of apoptosis due to HSP modulation in breast cancer cells.

Sarkar, Ruma; Mukherjee, Sutapa [Department of Environmental Carcinogenesis and Toxicology, Chittaranjan National Cancer Institute, 37, SP Mukherjee Road, Kolkata 700 026 (India)] [Department of Environmental Carcinogenesis and Toxicology, Chittaranjan National Cancer Institute, 37, SP Mukherjee Road, Kolkata 700 026 (India); Biswas, Jaydip [Chittaranjan National Cancer Institute, 37, SP Mukherjee Road, Kolkata 700 026 (India)] [Chittaranjan National Cancer Institute, 37, SP Mukherjee Road, Kolkata 700 026 (India); Roy, Madhumita, E-mail: mitacnci@yahoo.co.in [Department of Environmental Carcinogenesis and Toxicology, Chittaranjan National Cancer Institute, 37, SP Mukherjee Road, Kolkata 700 026 (India)] [Department of Environmental Carcinogenesis and Toxicology, Chittaranjan National Cancer Institute, 37, SP Mukherjee Road, Kolkata 700 026 (India)

2012-10-12

314

Naturally Occurring Compounds Elicit HIV-1 Replication in Chronically Infected Promonocytic Cells  

PubMed Central

Since antiretroviral therapy suppresses but does not eradicate HIV-1 infection, methods to purge viral reservoirs are required. Many strategies involve the reactivation of chronically HIV infected cells to induce the expression of integrated viral genome. In this study, five bioactive compounds, the plant derivatives 1-cinnamoyl-3,11-dihydroxymeliacarpin (CDM), nordihydroguaiaretic acid (NDGA), and curcumin (Cur) and the synthetic stigmasterol analogs (22S,23S)-22,23-dihydroxystigmast-4-en-3-one (compound 1) and (22S,23S)-3?-bromo-5?,22,23-trihydroxystigmastan-6-one (compound 2), were evaluated for their ability to elicit HIV replication in promonocytic (U1) and lymphocytic (H9+) HIV-1 chronically infected cells. The results revealed that natural compounds CDM, NDGA, and Cur were able to increase HIV-1 p24 antigen, determined by ELISA, only in latently infected promonocytic cells. CDM would reactivate HIV from latency by modulating the release of IL-6 and TNF-?, since the amount of both cytokines measured through ELISA significantly increased in U1 treated cells. Besides, NDGA increased ROS production, which might be related to the increase on p24 level observed in NDGA treated U1. These findings suggest that CDM, NDGA, and Cur might be candidates for further studies on latency-reversing therapeutics to eliminate latently HIV-1 reservoirs. PMID:24901006

Barquero, Andrea Alejandra; Dávola, María Eugenia; Riva, Diego Ariel; Mersich, Susana Esther; Alché, Laura Edith

2014-01-01

315

Mobilization and transport of naturally occurring enterococci in beach sands subject to transient infiltration of seawater.  

PubMed

This study explores the transport of enterococci (ENT) from naturally contaminated beach sands to the groundwater table via infiltrating seawater using field, laboratory, and modeling experiments. ENT were readily mobilized and transported through the unsaturated zone during infiltration events in both the field and laboratory column experiments. Detachment mechanisms were investigated using a modified version of HYDRUS-1D. Three models for detachment kinetics were tested. Detachment kinetics that are first order with respect to the rate of change in the water content and attached surface bacterial concentrations were found to provide a best fit between predicted and observed data. From these experimental and model results we conclude that detachment mechanisms associated with the rapid increases in pore water content such as air-water interface scouring and thin film expansion are likely drivers of ENT mobilization in the investigated system. These findings suggest that through-beach transport of ENT may be an important pathway through which ENT from beach sands are transported to beach groundwater where they may be discharged to coastal waters via submarine groundwater discharge. PMID:22533299

Russell, Todd L; Yamahara, Kevan M; Boehm, Alexandria B

2012-06-01

316

Laboratory studies using naturally occurring "green rust" to aid metal mine water remediation.  

PubMed

Green rust, an Fe (II) and (III) oxyhydroxy salt, can alter the aqueous oxidation state, mobility and toxicity, of inorganic contaminants and thus could have applications in water treatment. This paper discusses a series of stirred, open batch experiments designed to evaluate green rust, and its oxidised equivalent in this context comparing it to a ferrihydrite/goethite 'ochre'. Natural green rust was added to different mine waters as either a wet, reduced material or a dry, partially oxidised material. Experiments showed that the addition of either form accelerated the removal of potentially harmful elements from solution. Within one hour Fe, Al and Cu were completely removed from mine waters with initial concentrations of 80, 70 and 8.5mg/L, respectively, and Zn was reduced from 60 to <5mg/L. These experiments show the potential of green rust in mine water treatment, especially as it is able to remove problematic elements such as Al and Zn. The material is effective even after being dried and mostly oxidised. Changes to the pH and ORP of the mine waters and surface catalysis are the suggested mechanisms of accelerated removal of contaminants. PMID:21497995

Bearcock, Jenny M; Perkins, William T; Pearce, Nicholas J G

2011-06-15

317

Contrasts in growth and water sources in co-occurring Mediterranean riparian tree species: Evidence from tree ring isotopes and dendrochronology  

NASA Astrophysics Data System (ADS)

Riparian trees have growth responses to varying water sources that are more subtle than those of their upland counterparts, but differences in water use between co-occurring riparian species are not easily discerned by conventional dendrochronology. While tree ring isotopes have been developed as a useful tool for understanding past climate (temperature and precipitation) at the growth limits for particular species, relatively little research has investigated responses in tree growth in water-rich environments, where co-occurring tree species may express differential adaptation to water availability and shifting water sources. Better understanding of such subtle adaptations will improve predictions of the response of lowland riparian forests to climate changes that manifest as shifts in: regional ground water tables; the spatial/temporal distribution of precipitation; or volumes and timing of streamflow. We use an approach that combines dendrochronology and tree ring isotopes (?18O) to discern the relationships between tree growth and water sources for two contrasting, co-occurring Mediterranean riparian species-- Fraxinus excelsior and Populus nigra. We developed growth time series via two methods (one de-trended for climate) and extracted alpha-cellulose from tree rings to assess relative responses to water stress via ?18O, and we analyzed these data alongside streamflow and precipitation data for the Ain River basin in France. We find that both species exhibit decreased growth during drought years, but F. excelsior demonstrates more consistent annual growth than P. nigra. In contrast, oxygen isotopic values in P. nigra have low interannual variability compared with ?18O in F. excelsior. These differences suggest contrasting patterns of water use by these co-occurring species, wherein F. excelsior functions as an opportunist, scavenging water from the vadose zone where and when it cannot access groundwater. In contrast, the P. nigra demonstrates consistent groundwater usage (consistent with its moniker-obligate phreatophyte) and tends to struggle in drought years. These observations are consistent with ancillary data on rooting depths which show that F. excelsior maintains its roots above the gravel layer, where it can extract soil water from precipitation or overbank flooding. In contrast, P. nigra roots deeply into the phreatic zone without maintaining significant vadose zone roots, and is therefore less adaptable to rapid declines in the water table. These factors suggest, in contrast to prior work, that poplars may be more sensitive to drought than ash trees. Such dynamics in water use between such co-occurring, yet contrasting riparian trees within a riparian floodplain may indicate the response in succession and stand composition to climate changes or major anthropogenic impacts.

Singer, M. B.; Dufour, S.; Stella, J. C.; Piégay, H.; Johnstone, L.; Wilson, R.

2011-12-01

318

Natural gas constituent and carbon isotopic composition in petroliferous basins, China  

NASA Astrophysics Data System (ADS)

There are abundant gas resources in petroliferous basins of China. Large to midsize gas fields are found in Eastern, central and Western of China. However, origin, constituents and isotopic composition of natural gas in different gas fields are varied distinctly, and some present strong chemical secondary alteration and show variation both in age and space. Based on the systematic analysis of constituents and carbon isotope of a large number of gas samples, combined with the geological characteristics, this paper classifies the origins of the gases, explores the gas isotope characteristics and evolutionary regulation with the variation time and space, and further discusses the distinctive geochemistry of the gases in China. These gases are dominated by dry gas, its methane carbon isotope values range from -10‰ to -70‰, ethane from -16‰ to -52‰, propane from -13‰ to -43‰, and butane from -18‰ to -34‰. The carbon isotopes of most gases show the characteristics of humic-derived gas and crude oil cracked gas. In addition, large primary biogenic gas fields have been discovered in the Qaidam basin; inorganic-derived alkane gases have been discovered in deep of the Songliao Basin. Half of these gas fields are characterized by the alkane carbon isotope reversal in different degrees. Research indicates there are several reasons can result in carbon isotope reversal. Firstly, gas charge of different genetic types or different source in one gas reservoir may cause carbon isotope reversal. Besides, high-over mature evolution of gas can also lead to the carbon isotopic reversal of alkanes. Thirdly, secondary alteration of hydrocarbons may also result in abnormal distribution of carbon isotope, isotope transforms to unusual light and heavy.

Zhu, Guangyou; Wang, Zhengjun; Dai, Jinxing; Su, Jing

2014-02-01

319

Existence of long-lived isotopes of a superheavy element in natural Au  

E-print Network

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265 and abundance of (1-10)x10$^{-10}$ relative to Au has been found in a study of natural Au using an inductively coupled plasma - sector field mass spectrometer. The measured masses fit the predictions made for the masses of $^{261}$Rg and $^{265}$Rg (Z=111) and for some isotopes of nearby elements. The possibility that these isotopes belong to the recently discovered class of long-lived high spin super- and hyperdeformed isomeric states is discussed.

Marinov, A; Gentry, R V; Halicz, L; Kashiv, Y; Kolb, D; Miller, H W; Pape, A; Rodushkin, I; Segal, I

2007-01-01

320

Existence of long-lived isotopes of a superheavy element in natural Au  

E-print Network

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265 and abundance of (1-10)x10$^{-10}$ relative to Au has been found in a study of natural Au using an inductively coupled plasma - sector field mass spectrometer. The measured masses fit the predictions made for the masses of $^{261}$Rg and $^{265}$Rg (Z=111) and for some isotopes of nearby elements. The possibility that these isotopes belong to the recently discovered class of long-lived high spin super- and hyperdeformed isomeric states is discussed.

A. Marinov; I. Rodushkin; A. Pape; Y. Kashiv; D. Kolb; R. Brandt; R. V. Gentry; H. W. Miller; L. Halicz; I. Segal

2007-02-25

321

Determination of naturally-occurring actinides and their progeny in fresh water using ICP-MS and batch separation  

SciTech Connect

The determination of naturally-occurring actinides (including progeny such as {sup 230}Th) in fresh water is of significance in limnology, hydrology, and environmental monitoring. In many instances, these determinations require multiple analyses and a combination of radiometric and elemental measurement techniques (e.g., alpha spectrometry and thermal ionization mass spectrometry). In this work, we will describe the use of a single technique, inductively coupled plasma-mass spectrometry (ICP-MS), for these determinations. We will also describe the batch separation chemistry used to facilitate these determinations in ground and surface water, where natural analyte concentrations run between 1 {mu}g/L and 1 {mu}g/L.

Crain, J.S.; Alvarado, J.A.; Kiely, J.T. [Argonne National Lab., IL (United States)] [and others

1995-12-01

322

Collection, isolation and enrichment of naturally occurring magnetotactic bacteria from the environment.  

PubMed

Magnetotactic bacteria (MTB) are aquatic microorganisms that were first notably described in 1975 from sediment samples collected in salt marshes of Massachusetts (USA). Since then MTB have been discovered in stratified water- and sediment-columns from all over the world. One feature common to all MTB is that they contain magnetosomes, which are intracellular, membrane-bound magnetic nanocrystals of magnetite (Fe3O4) and/or greigite (Fe3S4) or both. In the Northern hemisphere, MTB are typically attracted to the south end of a bar magnet, while in the Southern hemisphere they are usually attracted to the north end of a magnet. This property can be exploited when trying to isolate MTB from environmental samples. One of the most common ways to enrich MTB is to use a clear plastic container to collect sediment and water from a natural source, such as a freshwater pond. In the Northern hemisphere, the south end of a bar magnet is placed against the outside of the container just above the sediment at the sediment-water interface. After some time, the bacteria can be removed from the inside of the container near the magnet with a pipette and then enriched further by using a capillary racetrack and a magnet. Once enriched, the bacteria can be placed on a microscope slide using a hanging drop method and observed in a light microscope or deposited onto a copper grid and observed using transmission electron microscopy (TEM). Using this method, isolated MTB may be studied microscopically to determine characteristics such as swimming behavior, type and number of flagella, cell morphology of the cells, shape of the magnetic crystals, number of magnetosomes, number of magnetosome chains in each cell, composition of the nanomineral crystals, and presence of intracellular vacuoles. PMID:23183960

Oestreicher, Zachery; Lower, Steven K; Lin, Wei; Lower, Brian H

2012-01-01

323

Collection, Isolation and Enrichment of Naturally Occurring Magnetotactic Bacteria from the Environment  

PubMed Central

Magnetotactic bacteria (MTB) are aquatic microorganisms that were first notably described in 19751 from sediment samples collected in salt marshes of Massachusetts (USA). Since then MTB have been discovered in stratified water- and sediment-columns from all over the world2. One feature common to all MTB is that they contain magnetosomes, which are intracellular, membrane-bound magnetic nanocrystals of magnetite (Fe3O4) and/or greigite (Fe3S4) or both3, 4. In the Northern hemisphere, MTB are typically attracted to the south end of a bar magnet, while in the Southern hemisphere they are usually attracted to the north end of a magnet3,5. This property can be exploited when trying to isolate MTB from environmental samples. One of the most common ways to enrich MTB is to use a clear plastic container to collect sediment and water from a natural source, such as a freshwater pond. In the Northern hemisphere, the south end of a bar magnet is placed against the outside of the container just above the sediment at the sediment-water interface. After some time, the bacteria can be removed from the inside of the container near the magnet with a pipette and then enriched further by using a capillary racetrack6 and a magnet. Once enriched, the bacteria can be placed on a microscope slide using a hanging drop method and observed in a light microscope or deposited onto a copper grid and observed using transmission electron microscopy (TEM). Using this method, isolated MTB may be studied microscopically to determine characteristics such as swimming behavior, type and number of flagella, cell morphology of the cells, shape of the magnetic crystals, number of magnetosomes, number of magnetosome chains in each cell, composition of the nanomineral crystals, and presence of intracellular vacuoles. PMID:23183960

Oestreicher, Zachery; Lower, Steven K.; Lin, Wei; Lower, Brian H.

2012-01-01

324

Naturally occurring bactericidal antibodies specific for Haemophilus influenzae Lipooligosaccharide are present in healthy adult individuals.  

PubMed

Nontypeable Haemophilus influenzae (NTHi), a typical mucosal pathogen largely responsible for respiratory infections and pediatric otitis media, has been increasingly recognized as a significant cause of invasive disease, especially in immunocompromised individuals. Lipooligosaccharide (LOS) is a conserved molecule with an important role in H. influenzae virulence and immune evasion, and it may be considered as a vaccine candidate. However, abilities of H. influenzae LOS to induce protective immune response are poorly understood. The goal of this study was to determine whether antibodies against LOS isolated from H. influenzae strains Eagan, Rd and NTHi 375 are present in the sera of normal individuals. Antigen specific IgG and IgM were studied in sera of 71 and 30 healthy adults, respectively. IgG specific for LOS of all three strains was ubiquitously present in our sample population while IgM specific for Eagan, Rd and NTHi 375 LOS compounds was detected in 37%, 63%, and 40% of samples, respectively. All tested serum samples exhibited bactericidal activity against all three H. influenzae strains; the removal of anti-LOS antibodies from the sera resulted in significant increases in bacterial survival of the corresponding strain. NTHi 375 exhibited the highest serum resistance, whereas the Rd strain was the least resistant. Serum bactericidal activity of anti-LOS antibody was mediated via the classical complement pathway. These findings suggest that in healthy adults, naturally acquired complement-activating anti-LOS antibodies significantly contribute to the overall serum bactericidal activity against both encapsulated and non-encapsulated strains of H. influenzae. PMID:25738817

Choi, Joshua; Nix, Eli B; Gaultier, Gabrielle N; Cox, Andrew D; McCready, William; Ulanova, Marina

2015-04-15

325

Allelic polymorphism of GIGANTEA is responsible for naturally occurring variation in circadian period in Brassica rapa.  

PubMed

GIGANTEA (GI) was originally identified by a late-flowering mutant in Arabidopsis, but subsequently has been shown to act in circadian period determination, light inhibition of hypocotyl elongation, and responses to multiple abiotic stresses, including tolerance to high salt and cold (freezing) temperature. Genetic mapping and analysis of families of heterogeneous inbred lines showed that natural variation in GI is responsible for a major quantitative trait locus in circadian period in Brassica rapa. We confirmed this conclusion by transgenic rescue of an Arabidopsis gi-201 loss of function mutant. The two B. rapa GI alleles each fully rescued the delayed flowering of Arabidopsis gi-201 but showed differential rescue of perturbations in red light inhibition of hypocotyl elongation and altered cold and salt tolerance. The B. rapa R500 GI allele, which failed to rescue the hypocotyl and abiotic stress phenotypes, disrupted circadian period determination in Arabidopsis. Analysis of chimeric B. rapa GI alleles identified the causal nucleotide polymorphism, which results in an amino acid substitution (S264A) between the two GI proteins. This polymorphism underlies variation in circadian period, cold and salt tolerance, and red light inhibition of hypocotyl elongation. Loss-of-function mutations of B. rapa GI confer delayed flowering, perturbed circadian rhythms in leaf movement, and increased freezing and increased salt tolerance, consistent with effects of similar mutations in Arabidopsis. Collectively, these data suggest that allelic variation of GI-and possibly of clock genes in general-offers an attractive target for molecular breeding for enhanced stress tolerance and potentially for improved crop yield. PMID:25775524

Xie, Qiguang; Lou, Ping; Hermand, Victor; Aman, Rashid; Park, Hee Jin; Yun, Dae-Jin; Kim, Woe Yeon; Salmela, Matti Juhani; Ewers, Brent E; Weinig, Cynthia; Khan, Sarah L; Schaible, D Loring P; McClung, C Robertson

2015-03-24

326

Nuclear genomic control of naturally occurring variation in mitochondrial function in Drosophila melanogaster  

PubMed Central

Background Mitochondria are organelles found in nearly all eukaryotic cells that play a crucial role in cellular survival and function. Mitochondrial function is under the control of nuclear and mitochondrial genomes. While the latter has been the focus of most genetic research, we remain largely ignorant about the nuclear-encoded genomic control of inter-individual variability in mitochondrial function. Here, we used Drosophila melanogaster as our model organism to address this question. Results We quantified mitochondrial state 3 and state 4 respiration rates and P:O ratio in mitochondria isolated from the thoraces of 40 sequenced inbred lines of the Drosophila Genetic Reference Panel. We found significant within-population genetic variability for all mitochondrial traits. Hence, we performed genome-wide association mapping and identified 141 single nucleotide polymorphisms (SNPs) associated with differences in mitochondrial respiration and efficiency (P ?1?×?10-5). Gene-centered regression models showed that 2–3 SNPs can explain 31, 13, and 18% of the phenotypic variation in state 3, state 4, and P:O ratio, respectively. Most of the genes tagged by the SNPs are involved in organ development, second messenger-mediated signaling pathways, and cytoskeleton remodeling. One of these genes, sallimus (sls), encodes a component of the muscle sarcomere. We confirmed the direct effect of sls on mitochondrial respiration using two viable mutants and their coisogenic wild-type strain. Furthermore, correlation network analysis revealed that sls functions as a transcriptional hub in a co-regulated module associated with mitochondrial respiration and is connected to CG7834, which is predicted to encode a protein with mitochondrial electron transfer flavoprotein activity. This latter finding was also verified in the sls mutants. Conclusions Our results provide novel insights into the genetic factors regulating natural variation in mitochondrial function in D. melanogaster. The integrative genomic approach used in our study allowed us to identify sls as a novel hub gene responsible for the regulation of mitochondrial respiration in muscle sarcomere and to provide evidence that sls might act via the electron transfer flavoprotein/ubiquinone oxidoreductase complex. PMID:23171078

2012-01-01

327

Characterization of Naturally Occurring Surface and Interface-Active Molecules in Petrochemicals by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

Microsoft Academic Search

High-resolution electrospray ionization Fourier Transform Ion Cyclotron Mass Spectrometry (ESI FT-ICR MS) is a robust method for identifying polar nitrogen, sulfur, and oxygen (–NSO) containing compounds in naturally occurring complex mixtures (i.e. coal, humic acids, crude oil, etc…) as it affords an average mass resolution m\\/?m50% ?100, 000 and mass accuracy <0.3 ppm. In Chapter 3, we apply ESI FT-ICR

Lateefah Ain Stanford

2006-01-01

328

Evaluation of Compton scattering and self-attenuation coefficient after ? -ray analysis of naturally occurring radioactive elements in environmental samples  

Microsoft Academic Search

Comparison of Compton scattering and Compton scattering cross section with self-attenuation coefficient were explained based\\u000a on the kinematic equation and Klein-Nishina formula. Naturally occurring elements, 238U (226Ra), 40K, 232Th (228Ra) and 137Cs were determined in sediments and water from Ismailia canal in Egypt which were found in the range of permissible level.\\u000a Self-attenuation coefficients, K, the ratio between photopeak detection

A. A. El-Sayed

2007-01-01

329

Laboratory methods for evaluating migrated high molecular weight hydrocarbons in marine sediments at naturally occurring oil seeps  

Microsoft Academic Search

A laboratory study has been conducted to determine the best methods for the detection of C10–C40 hydrocarbons at naturally occurring oil seeps in marine sediments. The results indicate that a commercially available method using n-C6 to extract sediments and gas chromatography–flame ionization detection (GC–FID) to screen the resulting extract is effective at recognizing the presence of migrated hydrocarbons at concentrations

Graham A. Logan; Michael A. Abrams; Nicola F. Dahdah; Emmanuelle Grosjean

2009-01-01

330

In Vivo and In Vitro Protein Ligation by Naturally Occurring and Engineered Split DnaE Inteins  

Microsoft Academic Search

BackgroundProtein trans-splicing by naturally occurring split DnaE inteins is used for protein ligation of foreign peptide fragments. In order to widen biotechnological applications of protein trans-splicing, it is highly desirable to have split inteins with shorter C-terminal fragments, which can be chemically synthesized.Principal FindingsWe report the identification of new functional split sites in DnaE inteins from Synechocystis sp. PCC6803 and

A. Sesilja Aranko; Sara Züger; Edith Buchinger; Hideo Iwaï; Hilal Lashuel

2009-01-01

331

Rare gas isotopic compositions in natural gases of Japan  

NASA Astrophysics Data System (ADS)

Isotopic and elemental compositions of rare gases in various types of gas samples collected in the Japanese Islands were investigated. Excess 3He was found in most samples. Many samples showed a regionally uniform high 3He/ 4He ratio of about 7 times the atmospheric ratio. The He concentrations varied from 0.6 to 1800 ppm, and they were low in CO 2-rich gases and high in N 2-rich gases. Ne isotopic deviations from the atmospheric Ne were detected in most volcanic gases. The deviations and the elemental abundance patterns in volcanic gases can be explained by a mixing between two components, one is mass fractionated rare gases and the other is isotopically atmospheric and is enriched in heavy rare gas elements. Ar was a mixture of mass fractionated Ar, atmospheric Ar and radiogenic Ar, and the contribution of radiogenic 40Ar was small in all samples. Except for He, elemental abundance patterns were progressively enriched in the heavier rare gases relative to the atmosphere. Several samples were highly enriched in Kr and Xe relative to the abundance pattern of dissolution equilibrium of atmospheric rare gases in water. The component which is highly enriched in heavy rare gases may be released from sedimentary materials in the crust.

Nagao, Keisuke; Takaoka, Nobuo; Matsubayashi, Osamu

1981-04-01

332

Stable water isotope characterization of human and natural impacts on land-atmosphere exchanges in the Amazon Basin  

Microsoft Academic Search

Stable water isotopes have been employed as a means of challenging, validating, and improving numerical models of the Amazon Basin since the 1980s. This paper serves as an exemplar of how characterization of human and natural impacts on surface-atmosphere water exchanges could beneficially exploit stable water isotope data and simulations. Interpretations of Amazonian isotopic data and model simulations are found

K. McGuffie; A. Henderson-Sellers

2004-01-01

333

Isotopes of Pennies  

NSDL National Science Digital Library

This lab activity from Science Netlinks is designed to explain the weighted averages that are used in average atomic mass calculations. Students can be expected to learn that isotopes of an element have different masses; that isotopes are atoms of the same element that have different numbers of neutrons; and that atomic mass is the weighted average of the naturally occurring isotopes of an element.

Science Netlinks

334

Prediction of rodent carcinogenic potential of naturally occurring chemicals in the human diet using high-throughput QSAR predictive modeling  

SciTech Connect

Consistent with the U.S. Food and Drug Administration (FDA) Critical Path Initiative, predictive toxicology software programs employing quantitative structure-activity relationship (QSAR) models are currently under evaluation for regulatory risk assessment and scientific decision support for highly sensitive endpoints such as carcinogenicity, mutagenicity and reproductive toxicity. At the FDA's Center for Food Safety and Applied Nutrition's Office of Food Additive Safety and the Center for Drug Evaluation and Research's Informatics and Computational Safety Analysis Staff (ICSAS), the use of computational SAR tools for both qualitative and quantitative risk assessment applications are being developed and evaluated. One tool of current interest is MDL-QSAR predictive discriminant analysis modeling of rodent carcinogenicity, which has been previously evaluated for pharmaceutical applications by the FDA ICSAS. The study described in this paper aims to evaluate the utility of this software to estimate the carcinogenic potential of small, organic, naturally occurring chemicals found in the human diet. In addition, a group of 19 known synthetic dietary constituents that were positive in rodent carcinogenicity studies served as a control group. In the test group of naturally occurring chemicals, 101 were found to be suitable for predictive modeling using this software's discriminant analysis modeling approach. Predictions performed on these compounds were compared to published experimental evidence of each compound's carcinogenic potential. Experimental evidence included relevant toxicological studies such as rodent cancer bioassays, rodent anti-carcinogenicity studies, genotoxic studies, and the presence of chemical structural alerts. Statistical indices of predictive performance were calculated to assess the utility of the predictive modeling method. Results revealed good predictive performance using this software's rodent carcinogenicity module of over 1200 chemicals, comprised primarily of pharmaceutical, industrial and some natural products developed under an FDA-MDL cooperative research and development agreement (CRADA). The predictive performance for this group of dietary natural products and the control group was 97% sensitivity and 80% concordance. Specificity was marginal at 53%. This study finds that the in silico QSAR analysis employing this software's rodent carcinogenicity database is capable of identifying the rodent carcinogenic potential of naturally occurring organic molecules found in the human diet with a high degree of sensitivity. It is the first study to demonstrate successful QSAR predictive modeling of naturally occurring carcinogens found in the human diet using an external validation test. Further test validation of this software and expansion of the training data set for dietary chemicals will help to support the future use of such QSAR methods for screening and prioritizing the risk of dietary chemicals when actual animal data are inadequate, equivocal, or absent.

Valerio, Luis G. [Division of Biotechnology and GRAS Notice Review, US Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Food Additive Safety, HFS-255, 5100 Paint Branch Parkway, College Park, MD 20740 (United States)]. E-mail: luis.valerio@FDA.HHS.gov; Arvidson, Kirk B. [Division of Food Contact Notifications, US Food and Drug Administration, Center for Food Safety and Applied Nutrition, 7Office of Food Additive Safety, HFS-255, 5100 Paint Branch Parkway, College Park, MD 20740 (United States); Chanderbhan, Ronald F. [Division of Biotechnology and GRAS Notice Review, US Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Food Additive Safety, HFS-255, 5100 Paint Branch Parkway, College Park, MD 20740 (United States); Contrera, Joseph F. [US Food and Drug Administration, Center for Drug Evaluation and Research, Office of Pharmaceutical Science, Informatics and Computational Safety Analysis Staff, Silver Spring, MD 20993 (United States)

2007-07-01

335

(220)Rn/(222)Rn isotope pair as a natural proxy for soil gas transport.  

PubMed

Radon (Rn) is a naturally occurring radioactive noble gas, which is ubiquitous in soil gas. Especially, its long-lived isotope (222)Rn (half-life: 3.82 d) gained widespread acceptance as a tracer for gas transport in soils, while the short-lived (220)Rn (half-life: 55.6 s) found less interest in environmental studies. However, in some cases, the application of (222)Rn as a tracer in soil gas is complex as its concentrations can be influenced by changes of the transport conditions or of the (222)Rn production of the soil material. Due to the different half-lives of (220)Rn and (222)Rn, the distances that can be traveled by the respective isotopes before decay differ significantly, with (220)Rn migrating over much shorter distances than (222)Rn. Therefore, the soil gas concentrations of (220)Rn and (222)Rn are influenced by processes on different length scales. In laboratory experiments in a sandbox, we studied the different transport behaviors of (220)Rn and (222)Rn resulting from changing the boundary conditions for diffusive transport and from inducing advective gas movements. From the results gained in the laboratory experiments, we propose the combined analysis of (220)Rn and (222)Rn to determine gas transport processes in soils. In a field study on soil gases in the cover soil of a capped landfill we applied the combined analysis of (220)Rn and (222)Rn in soil gas for the first time and showed the feasibility of this approach to characterize soil gas transport processes. PMID:24266394

Huxol, Stephan; Brennwald, Matthias S; Henneberger, Ruth; Kipfer, Rolf

2013-12-17

336

Chemical method for nitrogen isotopic analysis of ammonium at natural abundance.  

PubMed

We report a new chemical method to determine the (15)N natural abundance (?(15)N) for ammonium (NH4(+)) in freshwater (e.g., precipitation) and soil KCl extract. This method is based on the isotopic analysis of nitrous oxide (N2O). Ammonium is initially oxidized to nitrite (NO2(-)) by hypobromite (BrO(-)) using previously established procedures. NO2(-) is then quantitatively converted into N2O by hydroxylamine (NH2OH) under strongly acid conditions. The produced N2O is analyzed by a commercially available purge and cryogenic trap system coupled to an isotope ratio mass spectrometer (PT-IRMS). On the basis of a typical analysis size of 4 mL, the standard deviation of ?(15)N measurements is less than 0.3‰ and often better than 0.1‰ (3 to 5 replicates). Compared to previous methods, the technique here has several advantages and the potential to be used as a routine method for (15)N/(14)N analysis of NH4(+): (1) substantially simplified preparation procedures and reduced preparation time particularly compared to the methods in which diffusion or distillation is involved since all reactions occur in the same vial and separation of NH4(+) from solution is not required; (2) more suitability for low volume samples including those with low N concentration, having a blank size of 0.6 to 2 nmol; (3) elimination of the use of extremely toxic reagents (e.g., HN3) and/or the use of specialized denitrifying bacterial cultures which may be impractical for many laboratories. PMID:24654992

Liu, Dongwei; Fang, Yunting; Tu, Ying; Pan, Yuepeng

2014-04-15

337

Nitrogen-isotope analysis of groundwater nitrate in carbonate aquifers: Natural sources versus human pollution  

NASA Astrophysics Data System (ADS)

Results of nitrogen-isotope analyses of nitrate in the waters of the Cretaceous Edwards aquifer in Texas, U.S.A., indicate that the source of the nitrate is naturally-occurring nitrogen compounds in the recharge streams. In contrast, nitrogen isotopes of nitrate in the fresh waters of the Pleistocene Ironshore Formation on Grand Cayman Island, West Indies, indicate that human wastes are the source of the nitrate. The Cretaceous Edwards Limestone is a prolific aquifer that produces principally from fracture porosity along the Balcones Fault Zone. Recharge is primarily by streams crossing the fault zone. Rainfall is ˜ 70 cm yr. -1, and the water table is generally deeper than 30 m below land surface. The ?15 N of 73 samples of nitrate from Edwards waters ranged from + 1.9 to + 10‰ with an average of + 6.2‰. This ?15 N range is within the range of nitrate in surface water in the recharge streams ( ? 15N range = + 1 to + 8.3‰ ) and within the range of nitrate in surface water from the Colorado River, Texas, ( ? 15N range = + 1 to + 11‰ ). No sample was found to be enriched in 15N, which would suggest the presence of nitrate from animal waste ( ? 15N range = + 10 to + 22‰ ). The Ironshore Formation contains a small freshwater lens that is recharged entirely by percolation through the soil. Average rainfall is 165 cm yr. -1, and the water table is within 3 m of land surface. The ?15 N of four nitrate samples from water samples of the Ironshore Formation ranged from + 18 to + 23.9‰, which indicates a cesspool/septictank source of the nitrate. Limestone aquifers in humid environments that are recharged by percolation through the soil appear to be more susceptible to contamination by septic tanks than are aquifers in subhumid environments that feature thick unsaturated sections and are recharged by streams.

Kreitler, Charles W.; Browning, Lawrence A.

1983-02-01

338

MNA for Chlorinated Solvents and Fuel Oxygenates: Why It Occurs, How It Evolved, and Using Stable Carbon Isotopes to Predict Plume Behavior  

EPA Science Inventory

The organisms that degrade MtBE under anaerobic conditions are evolved to acquire energy for growth by using molecular hydrogen and carbonate ion to cleave methyl ether bonds. Methyl ether bonds are common in nature and the bond also occurs in MTBE. MTBE in contaminated ground...

339

MNA of Chlorinated Solvents and Fuel Oxygenates: Why it occurs, how it evolved, and using stable carbon isotopes to predict plume behavior  

EPA Science Inventory

The organisms that degrade MTBE under anaerobic conditions are evolved to acquire energy for growth by using molecular hydrogen and carbonate ion to cleave methyl ether bonds. Methyl ether bonds are common in nature and the bond also occurs in MTBE. MTBE in contaminated ground...

340

Water quality in the vicinity of Mosquito Creek Lake, Trumbull County, Ohio, in relation to the chemistry of locally occurring oil, natural gas, and brine  

USGS Publications Warehouse

Environmental samples collected in the Mosquito Creek Lake area were used to characterize water quality in relation to the chemistry of locally occurring oil, natural gas, and brine and to establish baseline water quality. Mosquito Creek Lake (a manmade reservoir) and the shallow bedrock aquifers near the lake are major sources of potable water in central Trumbull County. The city of Warren relies on the lake as a sole source of potable water. Some of the lake bottom may be in direct hydraulic connection with the underlying aquifers. The city of Cortland, along the southeastern shore of the lake, relies on the Cussewago Sandstone aquifer as a sole source of potable water. This aquifer subcrops beneath the glacio-fluvial sediments that underlie the lake. Nearly all residential homes around the lake, with the exception of homes in the city of Cortland, rely on domestic supply wells as a source of potable water. Oil and natural gas exploration and production have been ongoing in the Mosquito Creek Lakearea since the discovery of the historic Mecca Oil Pool in the Mississippian Berea and Cussewago Sandstones in 1860. Since the late 1970' s, the major drilling objective and zone of production is the Lower Silurian Clinton sandstone. The oil and natural gas resources of the Mosquito Creek Lake area, including reservoir pressure, production history, and engineering and abandonment practices are described in this report. The chemical and isotopic characteristics of the historic Mecca oil and natural gas are very different than those of the Clinton sandstone oil and natural gas. Gas chromatograms show that Mecca oil samples are extensively altered by biodegradation, whereas Clinton sandstone oils are not. Extensive alteration of Mecca oil is consistent with their occurrence at very shallow depths (less than 100 ft below land surface) where microbial activity can affect their composition. Also, the carbon-isotope composition of dissolved methane gas from Berea and Cussewago Sandstone water samples indicates that the gas is microbially generated, whereas the Clinton sandstone gases are thermogenically generated. Methane gas, in addition to crude oil, occurs naturally in the shallow Berea and Cussewago Sandstone aquifers in the Mosquito Creek Lake area and concentrations of dissolved methane are significant in the city of Cortland public-supply wells and in the domestic-supply wells near the southern shore of the lake. Water associated with oil and gas in the Clinton sandstone is a brine with high concentrations of chloride. Water from the Berea and Cussewago Sandstones, however, is fresh and potable. The contrasting geochemical characteristics are important for addressing water-quality issues that relate to oil and natural gas development in the Mosquito Creek area. A reexamination of the geologic framework and results of a subsurface-gas survey show that crude oil in the historic Mecca Oil Pool probably does not seep into Mosquito Creek Lake. Environmental samples show no evidence of any measurable release of oil, gas, or brine from the deeper Clinton sandstone oil and gas wells to the shallow aquifers, the lake, or lake tributaries. Brine is not associated with the hydrocarbons in the shallow Berea-Cussewago aquifer system and therefore cannot be a source of brine contamination. A mixing diagram constructed for dissolved bromide and chloride in surface water and water-supply wells shows no demonstrable mixing of these water resources with brine from the Clinton sandstone. There is some notable salinity in surface waters; however, the water is bromide poor, and a mixing diagram indicates that some local ground waters are influenced by halite solutions, presumably derived from leaching of road salt or from septic effluent.

Barton, G.J.; Burruss, R.C.; Ryder, R.T.

1998-01-01

341

Rapidly assessing changes in bone mineral balance using natural stable calcium isotopes  

PubMed Central

The ability to rapidly detect changes in bone mineral balance (BMB) would be of great value in the early diagnosis and evaluation of therapies for metabolic bone diseases such as osteoporosis and some cancers. However, measurements of BMB are hampered by difficulties with using biochemical markers to quantify the relative rates of bone resorption and formation and the need to wait months to years for altered BMB to produce changes in bone mineral density large enough to resolve by X-ray densitometry. We show here that, in humans, the natural abundances of Ca isotopes in urine change rapidly in response to changes in BMB. In a bed rest experiment, use of high-precision isotope ratio MS allowed the onset of bone loss to be detected in Ca isotope data after about 1 wk, long before bone mineral density has changed enough to be detectable with densitometry. The physiological basis of the relationship between Ca isotopes and BMB is sufficiently understood to allow quantitative translation of changes in Ca isotope abundances to changes in bone mineral density using a simple model. The rate of change of bone mineral density inferred from Ca isotopes is consistent with the rate observed by densitometry in long-term bed rest studies. Ca isotopic analysis provides a powerful way to monitor bone loss, potentially making it possible to diagnose metabolic bone disease and track the impact of treatments more effectively than is currently possible. PMID:22652567

Morgan, Jennifer L. L.; Skulan, Joseph L.; Gordon, Gwyneth W.; Romaniello, Stephen J.; Smith, Scott M.; Anbar, Ariel D.

2012-01-01

342

Upper limits for the existence of long-lived isotopes of roentgenium in natural gold  

NASA Astrophysics Data System (ADS)

A sensitive search for isotopes of a superheavy element (SHE) in natural gold materials has been performed with accelerator mass spectrometry at the Vienna Environmental Research Accelerator, which is based on a 3-MV tandem accelerator. Because the most likely SHE in gold is roentgenium (Rg, Z = 111), the search concentrated on Rg isotopes. Two different mass regions were explored: (i) For the neutron-deficient isotopes Rg261 and Rg265, abundance limits in gold of 3×10-16 were reached (no events observed). This is in stark contrast to the findings of Marinov [Int. J. Mod. Phys. EIMPEER0218-301310.1142/S021830130901280X 18, 621 (2009)], who reported positive identification of these isotopes with inductively coupled plasma sector field mass spectrometry in the (1-10)×10-10 abundance range. (ii) Theoretical models of SHEs predict a region of increased stability around the proton and neutron shell closures of Z = 114 and N = 184. We therefore investigated eight heavy Rg isotopes, ARg, A = 289, 290, 291, 292, 293, 294, 295, and 296. For six isotopes no events were observed, setting limits also in the 10-16 abundance range. For Rg291 and Rg294 we observed two and nine events, respectively, which results in an abundance in the 10-15 range. However, pileup of a particularly strong background in these cases makes a positive identification as Rg isotopes—even after pileup correction—unlikely.

Dellinger, F.; Kutschera, W.; Forstner, O.; Golser, R.; Priller, A.; Steier, P.; Wallner, A.; Winkler, G.

2011-01-01

343

Natural variation of magnesium isotopes in mammal bones and teeth from two South African trophic chains  

NASA Astrophysics Data System (ADS)

Isotopic fractionations accompanying element transfer through terrestrial ecosystems have the potential to shed light on ecological interactions between primary producers and consumers, but with the exception of carbon and nitrogen this potential has barely been exploited. Here, the magnesium stable isotope composition of bones and teeth of extant mammals from Kruger National Park (KNP) and Western Cape (WC), South Africa was measured for the first time. The nature of the geological substrate proves to be a major determinant of the ecosystem isotope baseline, as indicated by the lighter magnesium isotope ratios measured in WC mammals (ranging from -1.58‰ to -0.79‰) compared to those from KNP mammals (ranging from -1.01‰ to -0.04‰). Therefore, comparisons between the isotope signatures of taxa must be restricted to a pre-defined geographic area with a homogeneous substrate. In both parks, Mg shows slight enrichment in heavier isotopes from herbivores to carnivores. Plant remains trapped in the dentition of herbivores provide direct evidence of dietary source and, when available, were measured. In KNP only, ?26Mg of plant remains is systematically lighter than the values for herbivore teeth. These results invite further exploration of the variability of Mg isotopes in vertebrate ecosystems in order to test whether magnesium, a bio-essential element present in relatively large proportions in bone and teeth apatite, may serve as an additional trophic tracer to nitrogen, which is a constituent of collagen that rapidly degrades after burial.

Martin, Jeremy E.; Vance, Derek; Balter, Vincent

2014-04-01

344

Mechanistic insights into the formation of chloroform from natural organic matter using stable carbon isotope analysis  

NASA Astrophysics Data System (ADS)

Chloroform can be naturally formed in terrestrial environments (e.g. forest soils, peatland) by chlorination of natural organic matter (NOM). Recently, it was demonstrated that natural and anthropogenic chloroform have a distinctly different carbon isotope signature that makes it possible to identify its origin in soil and groundwater. In order to evaluate the contribution of different functional groups to chloroform production and factors controlling the isotopic composition of chloroform, carbon isotope trends during chlorination of model compounds, soil organic matter (SOM) and humic acids were evaluated, and apparent kinetic isotope effects (AKIEs) quantified. Phenol and propanone were selected as model compounds representing common functional groups in NOM. Chlorination was induced by hypochlorous acid to mimic natural chlorination. The pH ranged between 4 and 8 to cover typical soil conditions. For each model compound and pH, different AKIEs were observed. For phenol, the AKIE was normal at pH 4 (1.0156 ± 0.0012) and inverse at pH 8 (0.9900 ± 0.0007). For 2-propoanol, an opposite pH dependence was observed with an inverse AKIE at pH 4 (0.9935 ± 0.0007) and a normal AKIE at pH 8 (1.0189 ± 0.0016). The variations of the AKIE values suggest that the rate-limiting step of the reaction is either the re-hybridization of the carbon atom involved in chloroform formation or the hydrolysis of trichloroacetyl intermediates depending on the nature of functional group and pH. The chloroform formation from humic acid and SOM gives rise to small isotope variations. A comparison of the isotopic trends of chloroform formed from humic acid and SOM with those found for the model compounds suggest that opposed AKIE associated with the chlorination of phenolic and ketone moieties of NOM partly compensate each other during chlorination of NOM indicating that different types of functional groups contribute to chloroform formation.

Breider, Florian; Hunkeler, Daniel

2014-01-01

345

Nature and nurture: Environmental isotope story of the River Rhine  

Microsoft Academic Search

The total dissolved load of the Rhine river increases downstream due to the combined impact of natural and pollution loads. The natural background, controlled by geology, is soon swamped by pollution, particularly from salt and coal mining activities in Alsace and the Ruhr area. The Rhine is also a net source of CO2 from oxidation of excess organic productivity that

D. Buhl; R. D. Neuser; D. K. Richter; D. Riedel; B. Roberts; H. Strauss; J. Veizer

1991-01-01

346

Iron isotopes in the Seine River (France): Natural versus anthropogenic sources  

NASA Astrophysics Data System (ADS)

The determination of fluxes and isotope compositions of Fe transported from continents to the ocean is essential for understanding global surface Fe cycle and its effect on oceanic biological productivity. Contrasting to non-polluted rivers, Fe isotope composition in rivers strongly affected by human activities is poorly constrained. In this contribution, we present the first Fe isotope data in suspended particulate matter (SPM) and dissolved load of the human-impacted Seine River (France). Iron concentrations and isotope compositions, together with major and trace element concentrations, were measured for two sample sets: (1) a geographic transect along the river from headwater to estuary, and (2) a temporal series of samples collected in Paris from 2004 to 2007. In the Seine River, Fe is mostly carried by SPM (average 99% of the total Fe) rather than dissolved load. The high Fe enrichment factor (1.40, relative to natural fluvial pre-historical and headwater sediments) and strong correlation between SPM Fe and Zn concentrations (r2 = 0.70, n = 30) demonstrate a strong anthropogenic Fe input. The Fe isotope compositions in SPM show a very small range (?56Fe from -0.05‰ to 0.09‰) in spite of the large variations of Fe concentrations (from 1.78 to 4.17 wt.%) and are comparable to anthropogenic samples, suggesting that anthropogenic sources have similar Fe isotope composition to that of the natural background. In contrast, larger variations of Fe isotope compositions observed in the dissolved load (from -0.60‰ to 0.06‰) than that of SPM may provide a more promising means for tracing anthropogenic contributions to natural river systems. The ?56Fe and ?66Zn values of the dissolved loads are positively correlated (r2 = 0.62, n = 8), indicating a mixing between anthropogenic and natural end-members, enriched in light and heavy Fe isotopes respectively. Correlation between dissolved ?56Fe and DOC/Fe ratio (i.e. dissolved organic carbon/dissolved Fe concentrations) suggests that dissolved Fe of natural origin is mainly associated with organic colloids. The Fe compounds with low DOC/Fe ratio and ?56Fe values may correspond to anthropogenically-derived Fe-oxyhydroxide or sulfide colloids. Our study clearly demonstrates that polluted rivers transport an anthropogenic surplus flux of Fe that can be traced by coupling Fe and Zn isotopes. This surplus flux will fertilize the ocean and increase the primary productivity of phytoplankton, and thus may ultimately impact the global carbon cycle.

Chen, Jiu-Bin; Busigny, Vincent; Gaillardet, Jérôme; Louvat, Pascale; Wang, Yi-Na

2014-03-01

347

flvi-1, a common integration domain of feline leukemia virus in naturally occurring lymphomas of a particular type.  

PubMed Central

A locus in feline DNA, termed flvi-1, which may play an important role in the natural induction of lymphomas by feline leukemia virus (FeLV) was identified. Examination of a bank of 21 naturally occurring FeLV-positive feline lymphomas revealed that FeLV proviral integration occurs at flvi-1 in four independent tumors (19%). Independent integrations occurred within a 2.4-kilobase region of flvi-1, the probability of which by random chance can be estimated as 10(-16). Several lines of evidence, including sequence analysis of the long terminal repeat, demonstrated that proviruses integrated at flvi-1 are exogenously acquired and are oriented in the same transcriptional direction with respect to the locus. Molecularly cloned flvi-1 did not hybridize with probes representing several previously described proviral integration domains or with probes representing 10 oncogenes. The natural feline lymphomas examined in this study were heterogeneous with respect to tissue of origin, cell type, and number of monoclonal proviral integrations. The four tumors in which flvi-1 is interrupted were classified as members of a phenotypic subgroup containing seven lymphomas, i.e., at least four (57%) of seven lymphomas of this type contained FeLV proviral integration at flvi-1. Members of this phenotypic subgroup are non-T-cell lymphomas isolated from the spleen and contain an average of three proviruses, compared with an average of eight among all of the tumors examined. The small number of proviral integrations in tumors of this subgroup suggests that an early proviral integration event into flvi-1 can induce malignant change. Images PMID:2161948

Levesque, K S; Bonham, L; Levy, L S

1990-01-01

348

Distribution of the PBC-specific- (M2) and the naturally-occurring mitochondrial antigen- (NOMAg) systems in plants.  

PubMed Central

In previous studies it was demonstrated that antibodies in sera from patients with primary biliary cirrhosis (PBC) and their relatives can recognize two different antigen systems in the ATPase fraction prepared from beef heart mitochondria, namely the PBC-related M2- and the naturally occurring mitochondrial antigen (NOMAg)-related epitopes. Since separation of these two antigen systems could not be achieved using mammalian mitochondria, mitochondria from a wide spectrum of plants were analysed with respect to the presence of mitochondrial antigens. Mitochondria from 29 species of plants were prepared and tested by ELISA and Western blot using marker sera from patients with PBC reacting in the Western blot with M2a,b,c,d (alpha-ketoacid-dehydrogenase complex) and NOMAg-specific sera recognizing the three major epitopes epsilon, zeta, and eta at 65, 61 and 58 kD. Naturally occurring mitochondrial antibody (NOMA)-positive marker sera reacted in the ELISA with mitochondria from all plants, and the zeta/eta positive sera gave also a positive reaction at 61/58 kD in the Western blot while the epsilon epitope could not be visualized by this method. In contrast, the M2 antigen was detected preferentially in lower plants such as algae, fungi, and ferns. Analysing these data with respect to the evolution of proteins one would have to assume that the M2 antigen was lost in most higher plants or underwent some structural alterations. Furthermore, considering the fact that the M2- and the NOMAg-related epitopes could be only partially separated, i.e. there were no plant mitochondria showing only M2 but no NOMAg, one could speculate that anti-M2 antibodies are derived from the pool of naturally occurring antibodies. Images Fig. 2 PMID:1281057

Lang, P; Klein, R; Becker, E W; Berg, P A

1992-01-01

349

The atomic weight and isotopic composition of boron and their variation in nature  

SciTech Connect

The boron isotopic composition and atomic weight value and their variation in nature are reviewed. Questions are raised about the previously recommended value and the uncertainty for the atomic weight. The problem of what constitutes an acceptable range for normal material and what should then be considered geologically exceptional is discussed. Recent measurements make some previous decisions in need of re-evaluation.

Holden, N.E.

1993-08-01

350

Natural isotope tracers for assessing the mechanisms of heavy metal mobilization in copper ore tailings  

Microsoft Academic Search

The hydrodynamic mechanism of heavy metal mobilization from slag heaps in a former copper mining region of Saxony-Anhalt \\/ Germany has been investigated by means of natural isotope tracers. The heap is considered to be a black box, with no indication given, if the heavy metals in the spring water flowing out from the heap are leached from the processing

Knoeller Kay; Schubert Michael; Osenbrueck Karsten

351

Association of naturally occurring radionuclides in sludges from Drinking Water Treatment Plants previously optimized for their removal.  

PubMed

The raw water used in Drinking Water Treatment Plants (DWTPs) can present high values of naturally occurring radionuclides. In order to reduce this content, the routine working conditions of DWTPs were successfully modified. This meant that those radionuclides were accumulated in the sludges generated, whose radioactive content was frequently above the exemption levels. It therefore becomes necessary to assess the association of naturally occurring radionuclides in the sludges for their potential use as agricultural fertilizers. Two approaches were studied: (a) the effect of different sequential extraction methods applied to a selected sludge; and (b) the effect of the different contents of inorganic complexes dissolved in the input water on the composition of the sludges generated by two DWTPs with different origins of their input water. Uranium and radium were mainly associated with the carbonated and reducible fractions, while (210)Po and (228)Th were associated with the residual fraction. There were differences between the two speciation methods, but the order of bioavailable radionuclides was roughly the same: (226)Ra?(234,238)U>(228)Th>(210)Po. The major inorganic complexes content, mainly carbonate, in the raw water affected the radionuclide association. The greater the carbonate content in the raw water, the greater was the association of uranium and radium with the carbonated and easily reducible fractions. PMID:24238776

Baeza, A; Salas, A; Guillén, J; Muñoz-Serrano, A

2014-02-01

352

Molecular Imprint of Exposure to Naturally Occurring Genetic Variants of Human Cytomegalovirus on the T cell Repertoire  

NASA Astrophysics Data System (ADS)

Exposure to naturally occurring variants of herpesviruses in clinical settings can have a dramatic impact on anti-viral immunity. Here we have evaluated the molecular imprint of variant peptide-MHC complexes on the T-cell repertoire during human cytomegalovirus (CMV) infection and demonstrate that primary co-infection with genetic variants of CMV was coincident with development of strain-specific T-cell immunity followed by emergence of cross-reactive virus-specific T-cells. Cross-reactive CMV-specific T cells exhibited a highly conserved public T cell repertoire, while T cells directed towards specific genetic variants displayed oligoclonal repertoires, unique to each individual. T cell recognition foot-print and pMHC-I structural analyses revealed that the cross-reactive T cells accommodate alterations in the pMHC complex with a broader foot-print focussing on the core of the peptide epitope. These findings provide novel molecular insight into how infection with naturally occurring genetic variants of persistent human herpesviruses imprints on the evolution of the anti-viral T-cell repertoire.

Smith, Corey; Gras, Stephanie; Brennan, Rebekah M.; Bird, Nicola L.; Valkenburg, Sophie A.; Twist, Kelly-Anne; Burrows, Jacqueline M.; Miles, John J.; Chambers, Daniel; Bell, Scott; Campbell, Scott; Kedzierska, Katherine; Burrows, Scott R.; Rossjohn, Jamie; Khanna, Rajiv

2014-02-01

353

Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction  

SciTech Connect

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ?375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (?Sr SW = +13.8 to +41.6, where ?Sr SW is the deviation of the 87Sr/86Sr ratio from that of seawater in parts per 104); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

Elizabeth C. Chapman,† Rosemary C. Capo,† Brian W. Stewart,*,† Carl S. Kirby,‡ Richard W. Hammack,§

2012-02-24

354

Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction  

SciTech Connect

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of 375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (?{sub Sr}{sup SW} = +13.8 to +41.6, where ?{sub Sr}{sup SW} is the deviation of the {sup 87}Sr/{sup 86}Sr ratio from that of seawater in parts per 10{sup 4}); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

Chapman, Elizabeth C; Capo, Rosemary C.; Stewart, Brian W.; Kirby, Carl S.; Hammack, Richard W.; Schroeder, Karl T.; Edenborn, Harry M.

2012-03-20

355

Geochemical and strontium isotope characterization of produced waters from Marcellus Shale natural gas extraction.  

PubMed

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ~375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (?(Sr)(SW) = +13.8 to +41.6, where ?(Sr) (SW) is the deviation of the (87)Sr/(86)Sr ratio from that of seawater in parts per 10(4)); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters. PMID:22360406

Chapman, Elizabeth C; Capo, Rosemary C; Stewart, Brian W; Kirby, Carl S; Hammack, Richard W; Schroeder, Karl T; Edenborn, Harry M

2012-03-20

356

Analysis in natural time domain of geoelectric time series monitored prior two strong earthquakes occurred in Mexico  

NASA Astrophysics Data System (ADS)

The short-time prediction of seismic phenomena is currently an important problem in the scientific community. In particular, the electromagnetic processes associated with seismic events take in great interest since the VAN method was implemented. The most important features of this methodology are the seismic electrical signals (SES) observed prior to strong earthquakes. SES has been observed in the electromagnetic series linked to EQs in Greece, Japan and Mexico. By mean of the so-called natural time domain, introduced by Varotsos et al. (2001), they could characterize signals of dichotomic nature observed in different systems, like SES and ionic current fluctuations in membrane channels. In this work we analyze SES observed in geoelectric time series monitored in Guerrero, México. Our analysis concern with two strong earthquakes occurred, on October 24, 1993 (M=6.6) and September 14, 1995 (M=7.3). The time series of the first one displayed a seismic electric signal six days before the main shock and for the second case the time series displayed dichotomous-like fluctuations some months before the EQ. In this work we present the first results of the analysis in natural time domain for the two cases which seems to be agreeing with the results reported by Varotsos. P. Varotsos, N. Sarlis, and E. Skordas, Practica of the Athens Academy 76, 388 (2001).

Ramírez-Rojas, A.; Flores-Marquez, L. E.

2009-12-01

357

Isotopic disequilibrium effects in leaching of natural uraninite and thorianitc  

NASA Astrophysics Data System (ADS)

Fractional leach rates of 228Th that are greater than those of 232Th from natural uraninite and thorianite have been interpreted by Eyal and Fleischer in terms of ?-decay damage to the crystal lattice. An alternative interpretation proposed here is that the enhanced leaching of 228Th is due to its presence as interstitial ions.

Vance, E. R.; Gascoyne, M.

1987-09-01

358

Natural mass-dependent variations in the isotopic composition of molybdenum  

Microsoft Academic Search

We present the first observations of natural mass-dependent fractionation of the isotopic composition of molybdenum (Mo), using multi-collector inductively coupled plasma mass spectrometry. Variations in the isotopic composition of Mo are reported as ?97\\/95Mo (=((97Mo\\/95Mo)sample\\/(97Mo\\/95Mo)standard?1)×1000‰). External analytical precision of ?97\\/95Mo is 1‰ between sediments deposited under anoxic conditions (?97\\/95Mo=+1.02 to +1.52‰ relative to our in-house standard) and ferromanganese nodules (?97\\/95Mo=?0.63

J Barling; G. L Arnold; A. D Anbar

2001-01-01

359

Radiological Impact Associated to Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) from Coal-Fired Power Plants Emissions - 13436  

SciTech Connect

Certain materials used and produced in a wide range of non-nuclear industries contain enhanced activity concentrations of natural radionuclides. In particular, electricity production from coal is one of the major sources of increased human exposure to naturally occurring radioactive materials. A methodology was developed to assess the radiological impact due to natural radiation background. The developed research was applied to a specific case study, the Sines coal-fired power plant, located in the southwest coastline of Portugal. Gamma radiation measurements were carried out with two different instruments: a sodium iodide scintillation detector counter (SPP2 NF, Saphymo) and a gamma ray spectrometer with energy discrimination (Falcon 5000, Canberra). Two circular survey areas were defined within 20 km of the power plant. Forty relevant measurements points were established within the sampling area: 15 urban and 25 suburban locations. Additionally, ten more measurements points were defined, mostly at the 20-km area. The registered gamma radiation varies from 20 to 98.33 counts per seconds (c.p.s.) corresponding to an external gamma exposure rate variable between 87.70 and 431.19 nGy/h. The highest values were measured at locations near the power plant and those located in an area within the 6 and 20 km from the stacks. In situ gamma radiation measurements with energy discrimination identified natural emitting nuclides as well as their decay products (Pb-212, Pb-2142, Ra-226, Th-232, Ac-228, Th-234, Pa-234, U- 235, etc.). According to the results, an influence from the stacks emissions has been identified both qualitatively and quantitatively. The developed methodology accomplished the lack of data in what concerns to radiation rate in the vicinity of Sines coal-fired power plant and consequently the resulting exposure to the nearby population. (authors)

Dinis, Maria de Lurdes; Fiuza, Antonio; Soeiro de Carvalho, Jose; Gois, Joaquim [Geo-Environment and Resources Research Centre (CIGAR), Porto University, Faculty of Engineering - FEUP, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)] [Geo-Environment and Resources Research Centre (CIGAR), Porto University, Faculty of Engineering - FEUP, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Meira Castro, Ana Cristina [School of Engineering Polytechnic of Porto - ISEP, Rua Dr. Antonio Bernardino de Almeida, 431, 4200-072, Porto (Portugal)] [School of Engineering Polytechnic of Porto - ISEP, Rua Dr. Antonio Bernardino de Almeida, 431, 4200-072, Porto (Portugal)

2013-07-01

360

Novel and nontraditional use of stable isotope tracers to study metal bioavailability from natural particles.  

PubMed

We devised a novel tracing approach that involves enriching test organisms with a stable metal isotope of low natural abundance prior to characterizing metal bioavailability from natural inorganic particles. In addition to circumventing uncertainties associated with labeling natural particles and distinguishing background metals, the proposed "reverse labeling" technique overcomes many drawbacks inherent to using radioisotope tracers. Specifically, we chronically exposed freshwater snails ( Lymnaea stagnalis ) to synthetic water spiked with Cu that was 99.4% (65)Cu to increase the relative abundance of (65)Cu in the snail's tissues from ~32% to >80%. The isotopically enriched snails were then exposed to benthic algae mixed with Cu-bearing Fe-Al particles collected from the Animas River (Colorado), an acid mine drainage impacted river. We used (63)Cu to trace Cu uptake from the natural particles and inferred their bioavailability from calculation of Cu assimilation into tissues. Cu assimilation from these particles was 44%, indicating that 44% of the particulate Cu was absorbed by the invertebrate. This demonstrates that inorganic particulate Cu can be bioavailable. The reverse labeling approach shows great potential in various scientific areas such as environmental contamination and nutrition for addressing questions involving uptake of an element that naturally has multiple isotopes. PMID:23458345

Croteau, Marie-Noële; Cain, Daniel J; Fuller, Christopher C

2013-04-01

361

A method for the determination of vanadium and iron oxidation states in naturally occurring oxides and silicates  

USGS Publications Warehouse

A valence-specific analytical method for determining V3+ in ore minerals has been developed that involves two steps: dissolution of a mineral sample without disturbing the V3+/Vtot ratio, followed by determination of V3+ in the presence of V4+. The samples are dissolved in a mixture of hydrofluoric and sulphuric acids at 100?? in Teflon-lined reaction vessels. Tervalent vanadium is then determined colorimetrically by formation of a V3+-thiocyanate complex in aqueous-acetone medium. Fe3+ is measured semi-quantitatively in the same solution. The method has been tested with two naturally occurring samples containing vanadium and iron. The results obtained were supported by those obtained by other methods, including electron spin resonance spectroscopy, thermogravimetric analysis, and Mo??ssbauer spectroscopy. ?? 1985.

Wanty, R.B.; Goldhaber, M.B.

1985-01-01

362

Polarization dependent two-photon absorption spectroscopy on a naturally occurring biomarker (curcumin) in solution: A theoretical-experimental study  

NASA Astrophysics Data System (ADS)

We report on the theoretical-experimental analysis of the two-photon absorption (TPA) and two-photon circular-linear dichroism (TPCLD) spectra of (1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) in Tetrahydrofuran (THF) solution. The measurement of the full TPA spectrum of this molecule reveals a maximum TPA cross-section at 740 nm, i.e. more than 10 times larger than the maximum reported in the literature at 800 nm for the application of curcumin in bioimaging. The TPCLD spectrum exposes the symmetry of the main excited-states involved in the two-photon excitation process. TD-DFT calculations support the experimental results. These outcomes are expected to expand the application of natural-occurring dyes in bioimaging.

Tiburcio-Moreno, Jose A.; Alvarado-Gil, J. J.; Diaz, Carlos; Echevarria, Lorenzo; Hernández, Florencio E.

2013-09-01

363

Vincristine modulates the expression of Ki67 and apoptosis in naturally occurring canine transmissible venereal tumor (TVT).  

PubMed

We investigated eight adult dogs that were brought to veterinary clinics with a history of transmissible venereal tumors (TVT). Our goal was to demonstrate the occurrence of apoptosis and the cessation of cell proliferation at every phase of scheduled chemotherapy for naturally occurring TVT. Tissue samples were collected immediately after weekly treatments with vincristine sulfate and processed for histological purposes. Sections 5 ?m thick were stained by the TUNEL reaction for apoptosis and immunostained for Ki67 as a proliferation marker. We observed that after vincristine applications, tumor cell proliferation ceased and apoptosis increased. Ki67 HSCORE values were significantly lowered after the first and second treatments with the chemotherapeutic agent compared to controls, whereas TUNEL HSCORE values were significantly higher after two applications of vincristine compared to controls. Our results suggest that scheduled vincristine sulfate applications stabilize the induction of tumor regression by inducing apoptosis and preventing cell proliferation. PMID:22404564

Özalp, G R; Zik, B; Bastan, A; Peker, S; Özdemir-Salci, E S; Bastan, I; Darbaz, I; Salar, S; Karakas, K

2012-07-01

364

The nature, occurring contexts, and psychological implications of weight-related teasing in urban physical education programs.  

PubMed

This study examined the nature, occurring contexts, and psychological implications of weight-related teasing in urban physical education programs. Semistructured interviews were conducted with 47 participants from a large urban school district. Data were analyzed using inductive analysis and constant comparisons. Most overweight adolescents experienced many different types of teasing in physical education. Victims of teasing felt hurt and experienced uncomfortable feelings due to social comparisons. Overweight students who were not teased reported a variety of reasons. Teachers lacked awareness of and strategies to handle teasing of overweight students. There is a need to implement preventive policies and rules to eliminate weight-related teasing and create inclusive physical education environments. PMID:22808717

Li, Weidong; Rukavina, Paul

2012-06-01

365

Natural decrease of the intensity level of artificial radioactive isotopes in the Barents Sea  

NASA Astrophysics Data System (ADS)

The results of radioecological investigations carried out within the framework of the Russian-Finnish high-latitude expedition in 2007 are presented. The characteristics of the present-day accumulation level of the significant radioecological isotopes 137Cs, 90Sr and 239,240Pu in the Barents Sea are described. The comparative analysis is performed for the radiation pollution of the environment in the 1980s and 1990s and in the first decade of the 21st century. Natural purification processes in the marine environment are the main factors of the decrease in the intensity level of artificial radioactive isotopes. These processes include repeated dilution, nuclear decay, occlusion by sediments and suspended solid material, and accumulation by aquatic inhabitants. A stable decreasing trend is observed for the intensity level of artificial radioactive isotopes in the Barents Sea.

Matishov, G. G.; Matishov, D. G.; Solatie, D.; Kasatkina, N. E.; Leppanen, A.

2009-08-01

366

Existence of Long-Lived Isotopes of a Superheavy Element in Natural Au  

NASA Astrophysics Data System (ADS)

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265, and abundance of (1-10)×10-10 relative to Au, has been found in a study of natural Au using inductively coupled plasma-sector field mass spectrometry. The measured masses match the predictions for the masses of 261Rg and 265Rg (Z=111), and those of some isobars of nearby elements. Based on chemical arguments, it is proposed that they are most probably isotopes of Rg. It is deduced that long-lived isomeric states exist in these isotopes. The hypothesis that they belong to a new class of long-lived high spin super- and hyperdeformed isomeric states is discussed.

Marinov, A.; Rodushkin, I.; Pape, A.; Kashiv, Y.; Kolb, D.; Brandt, R.; Gentry, R. V.; Miller, H. W.; Halicz, L.; Segal, I.

367

Naturally occurring hypothermia is more advantageous than fever in severe forms of lipopolysaccharide- and Escherichia coli-induced systemic inflammation.  

PubMed

The natural switch from fever to hypothermia observed in the most severe cases of systemic inflammation is a phenomenon that continues to puzzle clinicians and scientists. The present study was the first to evaluate in direct experiments how the development of hypothermia vs. fever during severe forms of systemic inflammation impacts the pathophysiology of this malady and mortality rates in rats. Following administration of bacterial lipopolysaccharide (LPS; 5 or 18 mg/kg) or of a clinical Escherichia coli isolate (5 × 10(9) or 1 × 10(10) CFU/kg), hypothermia developed in rats exposed to a mildly cool environment, but not in rats exposed to a warm environment; only fever was revealed in the warm environment. Development of hypothermia instead of fever suppressed endotoxemia in E. coli-infected rats, but not in LPS-injected rats. The infiltration of the lungs by neutrophils was similarly suppressed in E. coli-infected rats of the hypothermic group. These potentially beneficial effects came with costs, as hypothermia increased bacterial burden in the liver. Furthermore, the hypotensive responses to LPS or E. coli were exaggerated in rats of the hypothermic group. This exaggeration, however, occurred independently of changes in inflammatory cytokines and prostaglandins. Despite possible costs, development of hypothermia lessened abdominal organ dysfunction and reduced overall mortality rates in both the E. coli and LPS models. By demonstrating that naturally occurring hypothermia is more advantageous than fever in severe forms of aseptic (LPS-induced) or septic (E. coli-induced) systemic inflammation, this study provides new grounds for the management of this deadly condition. PMID:22513748

Liu, Elaine; Lewis, Kevin; Al-Saffar, Hiba; Krall, Catherine M; Singh, Anju; Kulchitsky, Vladimir A; Corrigan, Joshua J; Simons, Christopher T; Petersen, Scott R; Musteata, Florin M; Bakshi, Chandra S; Romanovsky, Andrej A; Sellati, Timothy J; Steiner, Alexandre A

2012-06-15

368

Naturally Occurring Variation in the Glutathione-S-Transferase 4 Gene Determines Neurodegeneration After Traumatic Brain Injury  

PubMed Central

Abstract Aim: Genetic factors are important for outcome after traumatic brain injury (TBI), although exact knowledge of relevant genes/pathways is still lacking. We here used an unbiased approach to define differentially activated pathways between the inbred DA and PVG rat strains. The results prompted us to study further if a naturally occurring genetic variation in glutathione-S-transferase alpha 4 (Gsta4) affects the outcome after TBI. Results: Survival of neurons after experimental TBI is increased in PVG compared to the DA strain. Global expression profiling analysis shows the glutathione metabolism pathway to be the most regulated between the strains, with increased Gsta4 in PVG among top regulated transcripts. A congenic strain (R5) with a PVG genomic insert containing the Gsta4 gene on DA background displays a reversal of the strain pattern for Gsta4 expression and increased survival of neurons compared to DA. Gsta4 is known to effectively reduce 4-hydroxynonenal (4-HNE), a noxious by-product of lipid peroxidation. Immunostaining of 4-HNE was evident in both rat and human TBI. Intracerebral injection of 4-HNE resulted in neurodegeneration with increased levels of a marker for nerve injury in cerebrospinal fluid of DA compared to R5. Innovation: These findings provide strong support for the notion that the inherent capability of coping with increased 4-HNE after TBI affects outcome in terms of nerve cell loss. Conclusion: A naturally occurring variation in Gsta4 expression in rats affects neurodegeneration after TBI. Further studies are needed to explore if genetic variability in Gsta4 can be associated to outcome also in human TBI. Antioxid. Redox Signal. 18, 784–794. PMID:22881716

Ström, Mikael; Lindblom, Rickard; Aeinehband, Shahin; Bellander, Bo-Michael; Nyengaard, Jens R.; Lidman, Olle; Piehl, Fredrik

2013-01-01

369

The Effect of Naturally Occurring Chronic Kidney Disease on the Micro-Structural and Mechanical Properties of Bone  

PubMed Central

Chronic kidney disease (CKD) is a growing public health concern worldwide, and is associated with marked increase of bone fragility. Previous studies assessing the effect of CKD on bone quality were based on biopsies from human patients or on laboratory animal models. Such studies provide information of limited relevance due to the small size of the samples (biopsies) or the non-physiologic CKD syndrome studied (rodent models with artificially induced CKD). Furthermore, the type, architecture, structure and biology of the bone of rodents are remarkably different from human bones; therefore similar clinicopathologic circumstances may affect their bones differently. We describe the effects of naturally occurring CKD with features resembling human CKD on the skeleton of cats, whose bone biology, structure and composition are remarkably similar to those of humans. We show that CKD causes significant increase of resorption cavity density compared with healthy controls, as well as significantly lower cortical mineral density, cortical cross-sectional area and cortical cross-sectional thickness. Young's modulus, yield stress, and ultimate stress of the cortical bone material were all significantly decreased in the skeleton of CKD cats. Cancellous bone was also affected, having significantly lower trabecular thickness and bone volume over total volume in CKD cats compared with controls. This study shows that naturally occurring CKD has deleterious effects on bone quality and strength. Since many similarities exist between human and feline CKD patients, including the clinicopathologic features of the syndrome and bone microarchitecture and biology, these results contribute to better understanding of bone abnormalities associated with CKD. PMID:25333360

Meltzer, Hagar; Milrad, Moran; Brenner, Ori; Atkins, Ayelet; Shahar, Ron

2014-01-01

370

Functional characterization of naturally occurring melittin peptide isoforms in two honey bee species, Apis mellifera and Apis cerana.  

PubMed

Insect-derived antimicrobial peptides (AMPs) have diverse effects on antimicrobial properties and pharmacological activities such as anti-inflammation and anticancer properties. Naturally occurring genetic polymorphism have a direct and/or indirect influence on pharmacological effect of AMPs, therefore information on single nucleotide polymorphism (SNP) occurring in natural AMPs provides an important clue to therapeutic applications. Here we identified nucleotide polymorphisms in melittin gene of honey bee populations, which is one of the potent AMP in bee venoms. We found that the novel SNP of melittin gene exists in these two honey bee species, Apis mellifera and Apis cerana. Nine polymorphisms were identified within the coding region of the melittin gene, of which one polymorphism that resulted in serine (Ser) to asparagine (Asp) substitution that can potentially effect on biological activities of melittin peptide. Serine-substituted melittin (Mel-S) showed more cytotoxic effect than asparagine-substituted melittin (Mel-N) against E. coli. Also, Mel-N and Mel-S had different inhibitory effects on the production of inflammatory factors such as IL-6 and TNF-? in BV-2 cells. Moreover, Mel-S showed stronger cytotoxic activities than Mel-N peptide against two human ovarian cancer cell lines. Using carbon nanotube-based transistor, we here characterized that Mel-S interacted with small unilamellar liposomes more strongly than Mel-N. Taken together, our present study demonstrates that there exist different characteristics of the gene frequency and the biological activities of the melittin peptide in two honey bee species, Apis mellifera and A. cerana. PMID:24512991

Park, Doori; Jung, Je Won; Lee, Mi Ok; Lee, Si Young; Kim, Boyun; Jin, Hye Jun; Kim, Jiyoung; Ahn, Young-Joon; Lee, Ki Won; Song, Yong Sang; Hong, Seunghun; Womack, James E; Kwon, Hyung Wook

2014-03-01

371

Naturally-occurring tetrahydro-?-carboline alkaloids derived from tryptophan are oxidized to bioactive ?-carboline alkaloids by heme peroxidases.  

PubMed

?-Carbolines are indole alkaloids that occur in plants, foods, and endogenously in mammals and humans, and which exhibit potent biological, psychopharmacological and toxicological activities. They form from naturally-occurring tetrahydro-?-carboline alkaloids arising from tryptophan by still unknown way and mechanism. Results in this research show that heme peroxidases catalyzed the oxidation of tetrahydro-?-carbolines (i.e. 1,2,3,4-tetrahydro-?-carboline-3-carboxylic acid and 1-methyl-1,2,3,4-tetrahydro-?-carboline-3-carboxylic acid) into aromatic ?-carbolines (i.e. norharman and harman, respectively). This oxidation followed a typical catalytic cycle of peroxidases through redox intermediates I, II, and ferric enzyme. Both, plant peroxidases (horseradish peroxidase, HRP) and mammalian peroxidases (myeloperoxidase, MPO and lactoperoxidase, LPO) catalyzed the oxidation in an efficient manner as determined by kinetic parameters (VMAX and KM). Oxidation of tetrahydro-?-carbolines was inhibited by peroxidase inhibitors such as sodium azide, ascorbic acid, hydroxylamine and excess of H2O2. The formation of aromatic ?-carbolines by heme peroxidases can help to explain the presence and activity of these compounds in biological systems. PMID:25035927

Herraiz, Tomás; Galisteo, Juan

2014-08-15

372

Thermoluminescence (TL) Analysis and Fading Studies of Naturally Occurring Salt Irradiated by 500 mGy Gamma Rays  

SciTech Connect

The aim of the present study was to investigate the potential of the naturally occurring salt for the dosimetry purposes, using TL. The fine powder samples (20 mg) were irradiated by {gamma}- rays from 500 mGy to 2500 mGy by using Theratron-780C Cobalt-60 source, however, this paper discusses about 500 mGy only. The TL glow curve peak parameters were studied by using Chen's peak shape equation. TL glow curves were compared with fitted curves using glow curve deconvolution (GCD) method by using Kitis expression. The kinetic parameter values (E, b and s) so calculated, are in good agreement with those available in literature. The calculated energy values were also verified by using various heating rate (VHR) method. {chi}{sup 2} test and figure of merit (FOM) calculation was done to accept the goodness of fit between the curves. Fading studies of the sample showed a good fitting between the curves. The analysis suggests that natural salt should be considered for dosimetry purposes.

Tiwari, Ramesh Chandra; Pau, Kham Suan [Department of Physics, Mizoram University: Tanhril Campus, Aizawl-796004, Mizoram (India)

2011-10-20

373

Influence of naturally occurring dissolved organic matter, colloids, and cations on nanofiltration of pharmaceutically active and endocrine disrupting compounds.  

PubMed

This study examined the rejection of selected pharmaceutically active (PhAC) and endocrine disrupting compounds (EDCs) when using nanofiltration as a function of naturally occurring dissolved organic matter (DOM), colloidal particles, cations and their interactions. Lake Ontario water served as a source of natural DOM and colloidal particles. PhAC/EDC rejection experiments were conducted using raw Lake Ontario water and Lake Ontario water that was pre-treated with either ultrafiltration to remove colloidal particles, or fluidized ion exchange resins to remove DOM. Additionally, the concentration of cations (Ca(2+), Mg(2+), and Na(+)) in the raw and pre-treated water matrices was varied. While ionic PhACs and EDCs exhibited high rejections from all the water matrices examined, neutral compounds were most effectively rejected in water containing DOM and no colloids, and least effectively rejected from colloid-containing water with increased cations but no DOM. The presence of DOM significantly improved compound rejection and the increase in cation concentration significantly decreased rejection. The presence of colloids had comparatively little effect except to mitigate the impact of increased cation concentration, apparently providing some cation-buffering capacity. The sequence in which constituents are removed from waters during treatment may significantly impact PhAC and EDC removal, especially of neutral compounds. PMID:25016429

Sadmani, A H M Anwar; Andrews, Robert C; Bagley, David M

2014-12-01

374

Hydrolysis of a naturally occurring beta-glucoside by a broad-specificity beta-glucosidase from liver.  

PubMed Central

We have isolated from guinea-pig liver a broad-specificity beta-glucosidase of unknown function that utilizes as its substrate non-physiological aryl glycosides (e.g. 4-methylumbelliferyl beta-D-glucopyranoside, p-nitrophenyl beta-D-glucopyranoside). The present paper documents that this enzyme can be inhibited by various naturally occurring glycosides, including L-picein, dhurrin and glucocheirolin. In addition, L-picein, which acts as a competitive inhibitor of the broad-specificity beta-glucosidase (Ki 0.65 mM), is also a substrate for this enzyme (Km 0.63 mM; Vmax. 277,000 units/mg). Heat-denaturation, kinetic competition studies, chromatographic properties and pH optima all argue strongly that the broad-specificity beta-glucosidase is responsible for the hydrolysis of both the non-physiological aryl glycosides and L-picein. This paper demonstrates that beta-glucosidase can catalyse the hydrolysis of a natural glycoside, and may provide a key to understanding the function of this enigmatic enzyme. A possible role in the metabolism of xenobiotic compounds is discussed. PMID:3099756

LaMarco, K L; Glew, R H

1986-01-01

375

Enhanced dechlorination of carbon tetrachloride by Geobacter sulfurreducens in the presence of naturally occurring quinones and ferrihydrite.  

PubMed

The effect of naturally occurring quinones including lawsone (LQ), ubiquinone (UQ), juglone (JQ), and 1,4-naphthoquinone (NQ) on the biotransformation of carbon tetrachloride (CT) in the presence of Geobacter sulfurreducens and ferrihydrite was investigated. AQDS was used as the model compound for comparison. The reductive dissolution of ferrihydrite by G. sulfurreducens was enhanced by AQDS, NQ, and LQ. However, addition of UQ and JQ had little enhancement effect on Fe(II) production. The bioreduction efficiency and rate of ferrihydrite was highly dependent on the natural property and concentration of quinone compounds and the addition of low concentrations of LQ and NQ significantly accelerated the biotransformation rate of CT. The pseudo-first-order rate constants for CT dechlorination (kobsCT) in AQDS-, LQ- and NQ-amended batches were 5.4-5.8, 4.6-7.4 and 2.4-5.8 times, respectively, higher than those in the absence of quinone. A good relationship between kobsCT for CT dechlorination and bioreduction ratio of ferrihydrite was observed, indicating the important role of biogenic Fe(II) in dechlorination of CT under iron-reducing conditions. Spectroscopic analysis showed that AQDS and NQ could be reduced to semiquinones and hydroquinones, while only hydroquinones were generated in LQ-amended batches. PMID:24290294

Doong, Ruey-an; Lee, Chun-chi; Lien, Chia-min

2014-02-01

376

Ecological physiology of Synechococcus sp. strain SH-94-5, a naturally occurring cyanobacterium deficient in nitrate assimilation  

NASA Technical Reports Server (NTRS)

Synechococcus sp. strain SH-94-5 is a nitrate assimilation-deficient cyanobacterium which was isolated from an ammonium-replete hot spring in central Oregon. While this clone could grow on ammonium and some forms of organic nitrogen as sole nitrogen sources, it could not grow on either nitrate or nitrite, even under conditions favoring passive diffusion. It was determined that this clone does not express functional nitrate reductase or nitrite reductase and that the lack of activity of either enzyme is not due to inactivation of the cyanobacterial nitrogen control protein NtcA. A few other naturally occurring cyanobacterial strains are also nitrate assimilation deficient, and phylogenetic analyses indicated that the ability to utilize nitrate has been independently lost at least four times during the evolutionary history of the cyanobacteria. This phenotype is associated with the presence of environmental ammonium, a negative regulator of nitrate assimilation gene expression, which may indicate that natural selection to maintain functional copies of nitrate assimilation genes has been relaxed in these habitats. These results suggest how the evolutionary fates of conditionally expressed genes might differ between environments and thereby effect ecological divergence and biogeographical structure in the microbial world.

Miller, S. R.; Castenholz, R. W.

2001-01-01

377

What do N isotopes tell us about the biogeochemistry of natural gradients? (Invited)  

NASA Astrophysics Data System (ADS)

The two stable isotopes of nitrogen (N) hold great promise for biogeochemistry. Many processes prefer the lighter (14N) over the heavier (15N) isotope (they 'fractionate'), so the ratios of the two isotopes often differ within and across ecosystems. Our instruments are sufficiently awesome that we can observe these slight variations with great accuracy and precision, and these observations have revealed striking patterns along a number of natural environmental gradients. Because N isotopes integrate processes across time and space, there has been much hope that N isotopic patterns can unlock a mechanistic understanding of N dynamics, particularly at scales that are beyond the reach of experimentation. Is this a realistic hope? Certain patterns have clear, theory-based mechanistic implications. For example, the equilibrium (synonymous here with 'steady-state') isotopic signature of bulk soil N relative to net ecosystem N inputs indicates the degree of isotopic fractionation during ecosystem N losses. However, the nitrogen cycle is sufficiently complex that a given pattern could be produced from a variety of mechanisms, and in such cases it would be easy to infer a mechanism incorrectly. To expand our ability to make mechanistic inferences from N isotopic patterns, I extended a mathematical model of ecosystem N biogeochemistry to include explicit representations of the two N isotopes, constrained the theory with fractionation data, and analyzed the model using analytical approximations and numerical simulations. In this talk I will confine discussion to the submodel that studies ammonium and nitrate. The first three results I will discuss concern transient (non-equilibrium) dynamics, and serve as cautions for equilibrium-based interpretations. First, the time it takes to approach equilibrium is longer for N isotopic ratios than for the corresponding N pools, often by many fold, so isotopic ratios might be far from equilibrium even if pools are close. Second, the approach to equilibrium is often slower from above than below, so the average of measurements through time can be biased relative to the equilibrium. Third, the time it takes to approach equilibrium is shorter when N limits the processes of interest, often by an order of magnitude. In each of these cases, equilibrium-based inferences could be biased, but these results give guidance on the degree of bias and the circumstances under which is it expected, and thus give the ability to adjust equilibrium-based inferences accordingly. With these potential biases in mind, equilibrium results from the model yield mechanistic insights. For example, if some fractionation factors are known, data on N isotopic ratios in ammonium and nitrate allow estimates of the relative strengths of denitrification versus hydrologic nitrate loss. As another example, nitrification can be estimated from data on N isotopic ratios in ammonium and bulk soil N along with some fractionation factors. In this talk I will discuss these insights as they relate to N dynamics along natural environmental gradients.

Menge, D.

2013-12-01

378

Analysis of reserve pit sludge from unconventional natural gas hydraulic fracturing and drilling operations for the presence of technologically enhanced naturally occurring radioactive material (TENORM).  

PubMed

Soil and water (sludge) obtained from reserve pits used in unconventional natural gas mining was analyzed for the presence of technologically enhanced naturally occurring radioactive material (TENORM). Samples were analyzed for total gamma, alpha, and beta radiation, and specific radionuclides: beryllium, potassium, scandium, cobalt, cesium, thallium, lead-210 and -214, bismuth-212 and -214, radium-226 and -228, thorium, uranium, and strontium-89 and -90. Laboratory analysis confirmed elevated beta readings recorded at 1329 ± 311 pCi/g. Specific radionuclides present in an active reserve pit and the soil of a leveled, vacated reserve pit included 232Thorium decay series (228Ra, 228Th, 208Tl), and 226Radium decay series (214Pb, 214Bi, 210Pb) radionuclides. The potential for impact of TENORM to the environment, occupational workers, and the general public is presented with potential health effects of individual radionuclides. Current oversight, exemption of TENORM in federal and state regulations, and complexity in reporting are discussed. PMID:23552651

Rich, Alisa L; Crosby, Ernest C

2013-01-01

379

EasyDelta: A spreadsheet for kinetic modeling of the stable carbon isotope composition of natural gases  

NASA Astrophysics Data System (ADS)

A new kinetic model and an Excel © spreadsheet program for modeling the stable carbon isotope composition of natural gases is provided in this paper. The model and spreadsheet could be used to describe and predict the variances in stable carbon isotope of natural gases under both experimental and geological conditions with heating temperature or geological time. It is a user-friendly convenient tool for the modeling of isotope variation with time under experimental and geological conditions. The spreadsheet, based on experimental data, requires the input of the kinetic parameters of gaseous hydrocarbons generation. Some assumptions are made in this model: the conventional (non-isotope species) kinetic parameters represent the light isotope species; the initial isotopic value is the same for all parallel chemical reaction of gaseous hydrocarbons generation for simplicity, the re-exponential factor ratio, 13A/ 12A, is a constant, and both heavy and light isotope species have similar activation energy distribution. These assumptions are common in modeling of isotope ratios. The spreadsheet is used for searching the best kinetic parameters of the heavy isotope species to reach the minimum errors compared with experimental data, and then extrapolating isotopic changes to the thermal history of sedimentary basins. A short calculation example on the variation in ?13C values of methane is provided in this paper to show application to geological conditions.

Zou, Yan-Rong; Wang, Lianyuan; Shuai, Yanhua; Peng, Ping'an

2005-08-01

380

A Transient Model of Induced Natural Circulation Thermal Cycling for Hydrogen Isotope Separation  

SciTech Connect

The property of selective temperature dependence of adsorption and desorption of hydrogen isotopes by palladium is used for isotope separation. A proposal to use natural circulation of nitrogen to alternately heat and cool a packed bed of palladium coated beads is under active investigation, and a device consisting of two interlocking natural convection loops is being designed. A transient numerical model of the device has been developed to aid the design process. It is a one-dimensional finite-difference model, using the Boussinesq approximation. The thermal inertia of the pipe walls and other heat structures as well as the heater control logic is included in the model. Two system configurations were modeled and results are compared.

SHADDAY, MARTIN

2005-07-12

381

Acetylation and glycation of fibrinogen in vitro occur at specific lysine residues in a concentration dependent manner: A mass spectrometric and isotope labeling study  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Fibrinogen was incubated in vitro with glucose or aspirin. Black-Right-Pointing-Pointer Acetylations and glycations were found at twelve lysine sites by mass spectrometry. Black-Right-Pointing-Pointer The labeling by aspirin and glucose occurred dose-dependently. Black-Right-Pointing-Pointer No competition between glucose and aspirin for binding to fibrinogen was found. -- Abstract: Aspirin may exert part of its antithrombotic effects through platelet-independent mechanisms. Diabetes is a condition in which the beneficial effects of aspirin are less prominent or absent - a phenomenon called 'aspirin resistance'. We investigated whether acetylation and glycation occur at specific sites in fibrinogen and if competition between glucose and aspirin in binding to fibrinogen occurs. Our hypothesis was that such competition might be one explanation to 'aspirin resistance' in diabetes. After incubation of fibrinogen in vitro with aspirin (0.8 mM, 24 h) or glucose (100 mM, 5-10 days), we found 12 modified sites with mass spectrometric techniques. Acetylations in the {alpha}-chain: {alpha}K191, {alpha}K208, {alpha}K224, {alpha}K429, {alpha}K457, {alpha}K539, {alpha}K562, in the {beta}-chain: {beta}K233, and in the {gamma}-chain: {gamma}K170 and {gamma}K273. Glycations were found at {beta}K133 and {gamma}K75, alternatively {gamma}K85. Notably, the lysine 539 is a site involved in FXIII-mediated cross-linking of fibrin. With isotope labeling in vitro, using [{sup 14}C-acetyl]salicylic acid and [{sup 14}C]glucose, a labeling of 0.013-0.084 and 0.12-0.5 mol of acetylated and glycated adduct/mol fibrinogen, respectively, was found for clinically (12.9-100 {mu}M aspirin) and physiologically (2-8 mM glucose) relevant plasma concentrations. No competition between acetylation and glycation could be demonstrated. Thus, fibrinogen is acetylated at several lysine residues, some of which are involved in the cross-linking of fibrinogen. This may mechanistically explain why aspirin facilitates fibrin degradation. We find no support for the idea that glycation of fibrin(ogen) interferes with acetylation of fibrinogen.

Svensson, Jan, E-mail: jan.svensson@ki.se [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden) [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden); Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden); Bergman, Ann-Charlotte [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden)] [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden); Adamson, Ulf [Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden)] [Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden); Blombaeck, Margareta [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden)] [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden); Wallen, Hakan; Joerneskog, Gun [Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden)] [Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden)

2012-05-04

382

Existence of Long-Lived Isotopes of a Superheavy Element in Natural Au  

Microsoft Academic Search

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265, and abundance of (1-10)×10-10 relative to Au, has been found in a study of natural Au using inductively coupled plasma-sector field mass spectrometry. The measured masses match the predictions for the masses of 261Rg and 265Rg (Z=111), and those of some isobars of nearby elements. Based

A. Marinov; I. Rodushkin; A. Pape; Y. Kashiv; D. Kolb; R. Brandt; R. V. Gentry; H. W. Miller; L. Halicz; I. Segal

2009-01-01

383

The Inactivation of Human CYP2E1 by Phenethyl Isothiocyanate, a Naturally Occurring Chemopreventive Agent, and Its Oxidative Bioactivation  

PubMed Central

Phenethylisothiocyanate (PEITC), a naturally occurring isothiocyanate and potent cancer chemopreventive agent, works by multiple mechanisms, including the inhibition of cytochrome P450 (P450) enzymes, such as CYP2E1, that are involved in the bioactivation of carcinogens. PEITC has been reported to be a mechanism-based inactivator of some P450s. We describe here the possible mechanism for the inactivation of human CYP2E1 by PEITC, as well as the putative intermediate that might be involved in the bioactivation of PEITC. PEITC inactivated recombinant CYP2E1 with a partition ratio of 12, and the inactivation was not inhibited in the presence of glutathione (GSH) and not fully recovered by dialysis. The inactivation of CYP2E1 by PEITC is due to both heme destruction and protein modification, with the latter being the major pathway for inactivation. GSH-adducts of phenethyl isocyanate (PIC) and phenethylamine were detected during the metabolism by CYP2E1, indicating formation of PIC as a reactive intermediate following P450-catalyzed desulfurization of PEITC. Surprisingly, PIC bound covalently to CYP2E1 to form protein adducts but did not inactivate the enzyme. Liquid chromatography mass spectroscopy analysis of the inactivated CYP2E1 apo-protein suggests that a reactive sulfur atom generated during desulfurization of PEITC is involved in the inactivation of CYP2E1. Our data suggest that the metabolism of PEITC by CYP2E1 that results in the inactivation of CYP2E1 may occur by a mechanism similar to that observed with other sulfur-containing compounds, such as parathion. Digestion of the inactivated enzyme and analysis by SEQUEST showed that Cys 268 may be the residue modified by PIC. PMID:23371965

Yoshigae, Yasushi; Sridar, Chitra; Kent, Ute M.

2013-01-01

384

Evaluation of the varying Naturally Occurring Asbestos mitigation measures at School and Commercial construction projects in California  

NASA Astrophysics Data System (ADS)

In commercial development or K-12 school construction, project sites are often purchased and much of the planning process completed prior to an assessment of the soils proposed for excavation or potential offhaul. Geologic maps, while initially helpful for identifying potential hazards such as landslides and earthquake faults, are less helpful in the identification of naturally occurring hazardous minerals, such as the seven regulated minerals currently classified as asbestos. Geologic maps identify mafic and ultramafic bedrock zones; however, a skilled geologist with knowledge of asbestos hazards will further visualize the earth-shaping processes that may have resulted in the deposition of naturally occurring asbestos in locations outside mapped ultramafic zones including the base of an alluvial fan or within streambed channels. When sampled as an afterthought prior to disposal, property owners are surprised by the budget-crippling costs of waste handling and disposal of NOA, as well as mitigations required to protect the health of construction workers, the public, and future site occupants. The California Air Resources Board (CARB) continues to lead the way in evaluation and regulation of NOA, through development of the CARB 435 preparation and laboratory analytical method, local enforcement of the Asbestos Airborne Toxic Control Measure for Construction, Grading, Quarrying, and Surface Mining Operations (ATCM), and implementation of dust control measures to protect public health. A thorough site evaluation and construction design includes utilization of the sampling methods developed by the California Geological Survey, laboratory analytical methods within CARB 435, and mitigation measures required by CARB, DTSC, and OSHA for the protection of worker and public health after NOA is discovered. The site evaluation should additionally include an assessment of the future site usage, as regulations differ based on potential health affects to future occupants. Construction and long-term monitoring at an elementary school differs in regulatory requirements from construction of a commercial property. This presentation will highlight two case studies: a school project with several years of advance planning versus a commercial property where NOA was discovered weeks before the start of construction. The presentation will analyze the regulatory differences, mitigation measures, and consideration of the financial impacts that the discovery of NOA can have on a school versus a commercial project.

Kalika, S.

2012-12-01

385

Modeling the effects of naturally occurring organic carbon on chlorinated ethene transport to a public supply well.  

PubMed

The vulnerability of public supply wells to chlorinated ethene (CE) contamination in part depends on the availability of naturally occurring organic carbon to consume dissolved oxygen (DO) and initiate reductive dechlorination. This was quantified by building a mass balance model of the Kirkwood-Cohansey aquifer, which is widely used for public water supply in New Jersey. This model was built by telescoping a calibrated regional three-dimensional (3D) MODFLOW model to the approximate capture zone of a single public supply well that has a history of CE contamination. This local model was then used to compute a mass balance between dissolved organic carbon (DOC), particulate organic carbon (POC), and adsorbed organic carbon (AOC) that act as electron donors and DO, CEs, ferric iron, and sulfate that act as electron acceptors (EAs) using the Sequential Electron Acceptor Model in three dimensions (SEAM3D) code. SEAM3D was constrained by varying concentrations of DO and DOC entering the aquifer via recharge, varying the bioavailable fraction of POC in aquifer sediments, and comparing observed and simulated vertical concentration profiles of DO and DOC. This procedure suggests that approximately 15% of the POC present in aquifer materials is readily bioavailable. Model simulations indicate that transport of perchloroethene (PCE) and its daughter products trichloroethene (TCE), cis-dichloroethene (cis-DCE), and vinyl chloride (VC) to the public supply well is highly sensitive to the assumed bioavailable fraction of POC, concentrations of DO entering the aquifer with recharge, and the position of simulated PCE source areas in the flow field. The results are less sensitive to assumed concentrations of DOC in aquifer recharge. The mass balance approach used in this study also indicates that hydrodynamic processes such as advective mixing, dispersion, and sorption account for a significant amount of the observed natural attenuation in this system. PMID:24372440

Chapelle, Francis H; Kauffman, Leon J; Widdowson, Mark A

2014-09-01

386

Naturally occurring radioactive material from the aluminium industry--a case study: the Egyptian Aluminium Company, Nag Hammady, Egypt.  

PubMed

The activity concentrations and the gamma-absorbed dose rates of the terrestrial naturally occurring radionuclides (226)Ra and (232)Th were determined in samples of bauxite, alumina and aluminium dross tailings industrial waste (used to produce two types of alums) using high purity germanium (HPGe) gamma ray spectrometry. The bauxite and alumina are imported by Egyptalum (The Egyptian Aluminium Company, Nag Hammady, Egypt) from Guinea and India. The activity concentrations in the bauxite range from 29 +/- 1 to 112 +/- 6 Bq kg(-1) for (226)Ra, and 151 +/- 8 to 525 +/- 12 Bq kg(-1) for (232)Th, with mean values of 62 +/- 8 and 378 +/- 50 Bq kg(-1), respectively. With respect to alumina and tail, the mean values are 5.7 +/- 1.1 and 8.4 +/- 0.8 Bq kg(-1) for (226)Ra and 7.2 +/- 1.6 and 10.7 +/- 1.2 Bq kg(-1) for (232)Th. Potassium-40 was not detected in any of the studied samples. The measured activity concentrations of (226)Ra and (232)Th in bauxite are higher than the world average while in alumina and tail they are lower. As a measure of radiation hazard to the occupational workers and members of the public, the Ra equivalent activities and external gamma dose rates due to natural radionuclides at 1 m above the ground surface were calculated. The external gamma-radiation doses received by the Egyptalum workers are 97, 409, 8.5 and 12.7 microSv y(-1) for the Guinean and Indian bauxite, the alumina and tail, respectively, which is well below the recommended allowed dose of 1 mSv y(-1) for non-exposed workers. PMID:17146126

Abbady, Adel G E; El-Arabi, A M

2006-12-01

387

Naturally Occurring Incompatibilities between Different Culex pipiens pallens Populations as the Basis of Potential Mosquito Control Measures  

PubMed Central

Background Vector-borne diseases remain a threat to public health, especially in tropical countries. The incompatible insect technique has been explored as a potential control strategy for several important insect vectors. However, this strategy has not been tested in Culex pipiens pallens, the most prevalent mosquito species in China. Previous works used introgression to generate new strains that matched the genetic backgrounds of target populations while harboring a new Wolbachia endosymbiont, resulting in mating competitiveness and cytoplasmic incompatibility. The generation of these incompatible insects is often time-consuming, and the long-term stability of the newly created insect-Wolbachia symbiosis is uncertain. Considering the wide distribution of Cx. pipiens pallens and hence possible isolation of different populations, we sought to test for incompatibilities between natural populations and the possibility of exploiting these incompatibilities as a control strategy. Methodology/Principal Findings Three field populations were collected from three geographic locations in eastern China. Reciprocal cross results showed that bi-directional patterns of incompatibility existed between some populations. Mating competition experiments indicated that incompatible males could compete with cognate males in mating with females, leading to reduced overall fecundity. F1 offspring from incompatible crosses maintained their maternal crossing types. All three populations tested positive for Wolbachia. Removal of Wolbachia by tetracycline rendered matings between these populations fully compatible. Conclusions/Significance Our findings indicate that naturally occurring patterns of cytoplasmic incompatibility between Cx. pipiens pallens populations can be the basis of a control strategy for this important vector species. The observed incompatibilities are caused by Wolbachia. More tests including field trials are warranted to evaluate the feasibility of this strategy as a supplement to other control measures. PMID:23383354

Chen, Lin; Zhu, Changliang; Zhang, Donghui

2013-01-01

388

Modeling the effects of naturally occurring organic carbon on chlorinated ethene transport to a public supply well  

USGS Publications Warehouse

The vulnerability of public supply wells to chlorinated ethene (CE) contamination in part depends on the availability of naturally occurring organic carbon to consume dissolved oxygen (DO) and initiate reductive dechlorination. This was quantified by building a mass balance model of the Kirkwood-Cohansey aquifer, which is widely used for public water supply in New Jersey. This model was built by telescoping a calibrated regional three-dimensional (3D) MODFLOW model to the approximate capture zone of a single public supply well that has a history of CE contamination. This local model was then used to compute a mass balance between dissolved organic carbon (DOC), particulate organic carbon (POC), and adsorbed organic carbon (AOC) that act as electron donors and DO, CEs, ferric iron, and sulfate that act as electron acceptors (EAs) using the Sequential Electron Acceptor Model in three dimensions (SEAM3D) code. SEAM3D was constrained by varying concentrations of DO and DOC entering the aquifer via recharge, varying the bioavailable fraction of POC in aquifer sediments, and comparing observed and simulated vertical concentration profiles of DO and DOC. This procedure suggests that approximately 15% of the POC present in aquifer materials is readily bioavailable. Model simulations indicate that transport of perchloroethene (PCE) and its daughter products trichloroethene (TCE), cis-dichloroethene (cis-DCE), and vinyl chloride (VC) to the public supply well is highly sensitive to the assumed bioavailable fraction of POC, concentrations of DO entering the aquifer with recharge, and the position of simulated PCE source areas in the flow field. The results are less sensitive to assumed concentrations of DOC in aquifer recharge. The mass balance approach used in this study also indicates that hydrodynamic processes such as advective mixing, dispersion, and sorption account for a significant amount of the observed natural attenuation in this system.

Chapelle, Francis H.; Kauffman, Leon J.; Widdowson, Mark A.

2013-01-01

389

Modeling the Effects of Naturally Occurring Organic Carbon on Chlorinated Ethene Transport to a Public Supply Well†  

PubMed Central

The vulnerability of public supply wells to chlorinated ethene (CE) contamination in part depends on the availability of naturally occurring organic carbon to consume dissolved oxygen (DO) and initiate reductive dechlorination. This was quantified by building a mass balance model of the Kirkwood-Cohansey aquifer, which is widely used for public water supply in New Jersey. This model was built by telescoping a calibrated regional three-dimensional (3D) MODFLOW model to the approximate capture zone of a single public supply well that has a history of CE contamination. This local model was then used to compute a mass balance between dissolved organic carbon (DOC), particulate organic carbon (POC), and adsorbed organic carbon (AOC) that act as electron donors and DO, CEs, ferric iron, and sulfate that act as electron acceptors (EAs) using the Sequential Electron Acceptor Model in three dimensions (SEAM3D) code. SEAM3D was constrained by varying concentrations of DO and DOC entering the aquifer via recharge, varying the bioavailable fraction of POC in aquifer sediments, and comparing observed and simulated vertical concentration profiles of DO and DOC. This procedure suggests that approximately 15% of the POC present in aquifer materials is readily bioavailable. Model simulations indicate that transport of perchloroethene (PCE) and its daughter products trichloroethene (TCE), cis-dichloroethene (cis-DCE), and vinyl chloride (VC) to the public supply well is highly sensitive to the assumed bioavailable fraction of POC, concentrations of DO entering the aquifer with recharge, and the position of simulated PCE source areas in the flow field. The results are less sensitive to assumed concentrations of DOC in aquifer recharge. The mass balance approach used in this study also indicates that hydrodynamic processes such as advective mixing, dispersion, and sorption account for a significant amount of the observed natural attenuation in this system. PMID:24372440

Chapelle, Francis H; Kauffman, Leon J; Widdowson, Mark A

2014-01-01

390

Naturally occurring peer support through social media: the experiences of individuals with severe mental illness using YouTube.  

PubMed

Increasingly, people with diverse health conditions turn to social media to share their illness experiences or seek advice from others with similar health concerns. This unstructured medium may represent a platform on which individuals with severe mental illness naturally provide and receive peer support. Peer support includes a system of mutual giving and receiving where individuals with severe mental illness can offer hope, companionship, and encouragement to others facing similar challenges. In this study we explore the phenomenon of individuals with severe mental illness uploading videos to YouTube, and posting and responding to comments as a form of naturally occurring peer support. We also consider the potential risks and benefits of self-disclosure and interacting with others on YouTube. To address these questions, we used qualitative inquiry informed by emerging techniques in online ethnography. We analyzed n?=?3,044 comments posted to 19 videos uploaded by individuals who self-identified as having schizophrenia, schizoaffective disorder, or bipolar disorder. We found peer support across four themes: minimizing a sense of isolation and providing hope; finding support through peer exchange and reciprocity; sharing strategies for coping with day-to-day challenges of severe mental illness; and learning from shared experiences of medication use and seeking mental health care. These broad themes are consistent with accepted notions of peer support in severe mental illness as a voluntary process aimed at inclusion and mutual advancement through shared experience and developing a sense of community. Our data suggest that the lack of anonymity and associated risks of being identified as an individual with severe mental illness on YouTube seem to be overlooked by those who posted comments or uploaded videos. Whether or not this platform can provide benefits for a wider community of individuals with severe mental illness remains uncertain. PMID:25333470

Naslund, John A; Grande, Stuart W; Aschbrenner, Kelly A; Elwyn, Glyn

2014-01-01

391

Lithium isotopes in large rivers reveal the cannibalistic nature of modern continental weathering and erosion  

NASA Astrophysics Data System (ADS)

The erosion of major mountain ranges is thought to be largely cannibalistic, recycling sediments that were deposited in the ocean or on the continents prior to mountain uplift. Despite this recognition, it has not yet been possible to quantify the amount of recycled material that is presently transported by rivers to the ocean. Here, we have analyzed the Li content and isotope composition (?Li7) of suspended sediments sampled along river depth profiles and bed sands in three of the largest Earth's river systems (Amazon, Mackenzie and Ganga-Brahmaputra rivers). The ?Li7 values of river-sediments transported by these rivers range from +5.3 to -3.6‰ and decrease with sediment grain size. We interpret these variations as reflecting a mixture of unweathered rock fragments (preferentially transported at depth in the coarse fraction) and present-day weathering products (preferentially transported at the surface in the finest fraction). Only the finest surface sediments contain the complementary reservoir of Li solubilized by water-rock interactions within the watersheds. Li isotopes also show that river bed sands can be interpreted as a mixture between unweathered fragments of igneous and sedimentary rocks. A mass budget approach, based on Li isotopes, Li/Al and Na/Al ratios, solved by an inverse method allows us to estimate that, for the large rivers analyzed here, the part of solid weathering products formed by present-day weathering reactions and transported to the ocean do not exceed 35%. Li isotopes also show that the sediments transported by the Amazon, Mackenzie and Ganga-Brahmaputra river systems are mostly sourced from sedimentary rocks (>60%) rather than igneous rocks. This study shows that Li isotopes in the river particulate load are a good proxy for quantifying both the erosional rock sources and the fingerprint of present-day weathering processes. Overall, Li isotopes in river sediments confirm the cannibalistic nature of erosion and weathering.

Dellinger, Mathieu; Gaillardet, Jérôme; Bouchez, Julien; Calmels, Damien; Galy, Valier; Hilton, Robert G.; Louvat, Pascale; France-Lanord, Christian

2014-09-01

392

Fe and O isotope composition of meteorite fusion crusts: Possible natural analogues to chondrule formation?  

NASA Astrophysics Data System (ADS)

Meteorite fusion crust formation is a brief event in a high-temperature (2000-12,000 K) and high-pressure (2-5 MPa) regime. We studied fusion crusts and bulk samples of 10 ordinary chondrite falls and 10 ordinary chondrite finds. The fusion crusts show a typical layering and most contain vesicles. All fusion crusts are enriched in heavy Fe isotopes, with ?56Fe values up to +0.35‰ relative to the solar system mean. On average, the ?56Fe of fusion crusts from finds is +0.23‰, which is 0.08‰ higher than the average from falls (+0.15‰). Higher ?56Fe in fusion crusts of finds correlate with bulk chondrite enrichments in mobile elements such as Ba and Sr. The ?56Fe signature of meteorite fusion crusts was produced by two processes (1) evaporation during atmospheric entry and (2) terrestrial weathering. Fusion crusts have either the same or higher ?18O (0.9-1.5‰) than their host chondrites, and the same is true for ?17O. The differences in bulk chondrite and fusion crust oxygen isotope composition are explained by exchange of oxygen between the molten surface of the meteorites with the atmosphere and weathering. Meteorite fusion crust formation is qualitatively similar to conditions of chondrule formation. Therefore, fusion crusts may, at least to some extent, serve as a natural analogue to chondrule formation processes. Meteorite fusion crust and chondrules exhibit a similar extent of Fe isotope fractionation, supporting the idea that the Fe isotope signature of chondrules was established in a high-pressure environment that prevented large isotope fractionations. The exchange of O between a chondrule melt and an 16O-poor nebula as the cause for the observed nonmass dependent O isotope compositions in chondrules is supported by the same process, although to a much lower extent, in meteorite fusion crusts.

Hezel, Dominik C.; Poole, Graeme M.; Hoyes, Jack; Coles, Barry J.; Unsworth, Catherine; Albrecht, Nina; Smith, Caroline; RehkäMper, Mark; Pack, Andreas; Genge, Matthew; Russell, Sara S.

2015-02-01

393

Demonstrating a natural origin of chloroform in groundwater using stable carbon isotopes.  

PubMed

Chloroform has been for a long time considered only as an anthropogenic contaminant. The presence of chloroform in forest soil and groundwater has been widely demonstrated. The frequent detection of chloroform in groundwater in absence of other contaminants suggests that chloroform is likely produced naturally. Compound-specific isotope analysis of chloroform was performed on soil-gas and groundwater samples to elucidate whether its source is natural or anthropogenic. The ?(13)C values of chloroform (-22.8 to -26.2‰) present in soil gas collected in a forested area are within the same range as the soil organic matter (-22.6 to -28.2‰) but are more enriched in (13)C compared to industrial chloroform (-43.2 to -63.6‰). The ?(13)C values of chloroform at the water table (-22.0‰) corresponded well to the ?(13)C of soil gas chloroform, demonstrating that the isotope signature of chloroform is maintained during transport through the unsaturated zone. Generally, the isotope signature of chloroform is conserved also during longer range transport in the aquifer. These ?(13)C data support the hypothesis that chloroform is naturally formed in some forest soils. These results may be particularly relevant for authorities' regulation of chloroform which in the case of Denmark was very strict for groundwater (<1 ?g/L). PMID:22554551

Hunkeler, Daniel; Laier, Troels; Breider, Florian; Jacobsen, Ole Stig

2012-06-01

394

Factors associated with concentrations of select cytokine and acute phase proteins in dairy cows with naturally occurring clinical mastitis.  

PubMed

The objective of the current observational study was to determine the potential associations between cow factors, clinical mastitis (CM) etiology, and concentrations of select acute phase proteins and cytokines in milk from affected quarters of cows with CM. Cows with CM (n=197) were grouped based on systemic disease severity, milk culture result, parity, days in milk (DIM), previous CM occurrence, and season of the year when CM occurred. Concentrations of lipopolysaccharide-binding protein (LBP), haptoglobin (Hp), BSA, IFN-gamma, tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-8, IL-10, IL-12, transforming growth factor (TGF)-alpha, and TGF-beta and activity of lactate dehydrogenase (LDH) were evaluated. Differences in the least squares means log(10) transformed concentrations of these proteins were compared using multiple linear regression mixed models. The milk concentrations of LBP, Hp, IL-1beta, IL-10, and IL-12, and activity of LDH in milk were higher in cows with moderate to severe versus mild systemic disease. The concentrations of Hp, BSA, IL-1beta, and IL-10 in milk were higher in cows with a gram-negative versus gram-positive milk culture result. Season of the year when CM occurred was associated with the concentration of all proteins evaluated except for IL-1beta and IL-12. Concentrations were higher in the winter versus summer except for Hp and TGF-beta, for which the opposite was true. Concentrations of LBP, IL-10, and IL-12, and LDH activity in milk were associated with DIM group. Except for LBP, these proteins were lower in cows with CM during the first 60 DIM versus those in mid or later lactation. Interferon-gamma, TNF-alpha, and IL-8 were undetectable in 67, 31, and 20% of samples, respectively. Detection of IFN-gamma and IL-8 was associated with season, and detection of TNF-alpha and IL-8 was associated with systemic disease severity. The current study provides the most comprehensive report of milk concentrations of innate immune response proteins in cows with naturally occurring CM and identifies factors that potentially influence those concentrations. Further investigation into the seasonal variation of cytokine production and its potential effect on the outcome of CM is warranted. Furthermore, the results of this study provide useful data for planning future studies examining the role of the innate immune response in CM. PMID:20494154

Wenz, J R; Fox, L K; Muller, F J; Rinaldi, M; Zeng, R; Bannerman, D D

2010-06-01

395

Evolution of isotopic composition of reprocessed uranium during the multiple recycling in light water reactors with natural uranium feed  

SciTech Connect

A complex approach based on the consistent modeling of neutron-physics processes and processes of cascade separation of isotopes is applied for analyzing physical problems of the multiple usage of reprocessed uranium in the fuel cycle of light water reactors. A number of scenarios of multiple recycling of reprocessed uranium in light water reactors are considered. In the process, an excess absorption of neutrons by the {sup 236}U isotope is compensated by re-enrichment in the {sup 235}U isotope. Specific consumptions of natural uranium for re-enrichment of the reprocessed uranium depending on the content of the {sup 232}U isotope are obtained.

Smirnov, A. Yu., E-mail: a.y.smirnoff@rambler.ru; Sulaberidze, G. A. [National Research Nuclear University MEPhI (Russian Federation); Alekseev, P. N.; Dudnikov, A. A.; Nevinitsa, V. A., E-mail: neva@dhtp.kiae.ru; Proselkov, V. N.; Chibinyaev, A. V. [Russian Research Centre Kurchatov Institute (Russian Federation)

2012-12-15

396

A serine protease inhibitor, protease nexin I, rescues motoneurons from naturally occurring and axotomy-induced cell death.  

PubMed Central

Protease nexin I (PNI) is a member of the family of serine protease inhibitors (serpins) that have been shown to promote neurite outgrowth in vitro from different neuronal cell types. These include neuroblastoma cells, hippocampal neurons, and sympathetic neurons. Free PNI protein is markedly decreased in various anatomical brain regions, including hippocampus, of patients with Alzheimer disease. Here, we report that PNI rescued spinal motoneurons during the period of naturally occurring (programmed) cell death in the chicken in a dose-dependent fashion. Furthermore, PNI prevented axotomy-induced spinal motoneuron death in the neonatal mouse. The survival effect of PNI on motoneurons during the period of programmed cell death was not associated with increased intramuscular nerve branching. PNI also significantly increased the nuclear size of motoneurons during the period of programmed cell death and prevented axotomy-induced atrophy of surviving motoneurons. These results are consistent with the possible role of PNI as a neurotrophic agent. They also support the idea that serine proteases or, more precisely, the balance of proteases and serpins may be involved in regulating the fate of neuronal cells during development. Images Fig. 1 Fig. 2 Fig. 3 PMID:7846074

Houenou, L J; Turner, P L; Li, L; Oppenheim, R W; Festoff, B W

1995-01-01

397

Biochemical changes in the jejunal mucosa of dogs with a naturally occurring enteropathy associated with bacterial overgrowth.  

PubMed

The subcellular biochemical features of a naturally occurring enteropathy in the dog associated with bacterial overgrowth have been examined. Affected animals comprised a group of 10 German Shepherd dogs with raised serum folate and reduced vitamin B12 concentrations, mild steatorrhoea, reduced xylose absorption, and normal exocrine pancreatic function. Culture of duodenal juice showed bacterial overgrowth with mixed flora, most frequently including enterococci and Escherichia coli. Examination of peroral jejunal biopsies revealed predominantly minimal histological but distinct biochemical abnormalities in the mucosa. The specific activity of alkaline phosphatase was decreased, isopycnic density gradient centrifugation showing a marked loss particularly of the brush border component of enzyme activity. In contrast, gamma-glutamyl transferase activity was enhanced in brush border fragments of slightly increased modal density, but there were no changes in the activities of the carbohydrases, zinc-resistant alpha-glucosidase, maltase, sucrase, and lactase or of the peptidase, leucyl-2-naphthylamidase. Activities of lysosomal enzymes were increased and there was evidence for enhanced lysosomal fragility and mitochondrial disruption. The activities and density gradient distributions of marker enzymes for basal-lateral membranes, endoplasmic reticulum and peroxisomes were essentially unaltered. These findings show that bacterial colonisation of the proximal small intestine may be associated with specific alterations in microvillus membrane proteins and provide biochemical evidence for intracellular damage to the enterocytes. PMID:6745719

Batt, R M; Carter, M W; Peters, T J

1984-08-01

398

A Naturally Occurring GIP Receptor Variant Undergoes Enhanced Agonist-Induced Desensitization, Which Impairs GIP Control of Adipose Insulin Sensitivity  

PubMed Central

Glucose-dependent insulinotropic polypeptide (GIP), an incretin hormone secreted from gastrointestinal K cells in response to food intake, has an important role in the control of whole-body metabolism. GIP signals through activation of the GIP receptor (GIPR), a G-protein-coupled receptor (GPCR). Dysregulation of this pathway has been implicated in the development of metabolic disease. Here we demonstrate that GIPR is constitutively trafficked between the plasma membrane and intracellular compartments of both GIP-stimulated and unstimulated adipocytes. GIP induces a downregulation of plasma membrane GIPR by slowing GIPR recycling without affecting internalization kinetics. This transient reduction in the expression of GIPR in the plasma membrane correlates with desensitization to the effects of GIP. A naturally occurring variant of GIPR (E354Q) associated with an increased incidence of insulin resistance, type 2 diabetes, and cardiovascular disease in humans responds to GIP stimulation with an exaggerated downregulation from the plasma membrane and a delayed recovery of GIP sensitivity following cessation of GIP stimulation. This perturbation in the desensitization-resensitization cycle of the GIPR variant, revealed in studies of cultured adipocytes, may contribute to the link of the E354Q variant to metabolic disease. PMID:25047836

Mohammad, Sameer; Patel, Rajesh T.; Bruno, Joanne; Panhwar, Muhammad Siyab; Wen, Jennifer

2014-01-01

399

Synthesis of D-lyxitol and D-ribitol analogues of the naturally occurring glycosidase inhibitor salacinol.  

PubMed

The synthesis of analogues of the naturally occurring glycosidase inhibitor, salacinol, in which the D-arabinitol ring has been replaced by D-lyxitol or D-ribitol, is described. Salacinol is one of the active principles in the aqueous extracts of Salacia reticulata, which are traditionally used in India and Sri Lanka for the treatment of Type II diabetes. The synthetic strategy relies on the nucleophilic attack of 1,4-anhydro-2,3,5-tri-O-p-methoxybenzyl-4-thio-D-lyxitol or 1,4-anhydro-2,3,5-tri-O-p-methoxybenzyl-4-thio-D-ribitol at the least hindered carbon of the benzylidene-protected L-cyclic sulfate derived from L-erythritol. Screening of these compounds against recombinant human maltase glucoamylase (MGA), a critical intestinal glucosidase involved in the processing of oligosaccharides of glucose into glucose itself, shows that they are not effective inhibitors of MGA and demonstrates the importance of the d-arabinitol configuration in the heterocyclic ring for effective inhibition. PMID:16198322

Kumar, Nag S; Pinto, B Mario

2005-12-12