Search results for "ISOTOPES"

showing 10 items of 1216 documents

Persistent link between Caribbean precipitation and Atlantic Ocean circulation during the Last Glacial revealed by a speleothem record from Puerto Ri…

2020

The sensitivity of tropical Atlantic precipitation patterns to the mean position of the Intertropical Convergence Zone (ITCZ) at different time scales is well‐known. However, recent research suggests a more complex behavior of the northern hemispheric tropical rain belt related to the ITCZ in the western tropical Atlantic. Here we present a precisely dated speleothem multi‐proxy record from a well‐monitored cave in Puerto Rico, covering the period between 46.2 and 15.3 ka. The stable isotope and trace element records document a pronounced response of regional rainfall to abrupt climatic excursions in the North Atlantic across the Last Glacial such as Heinrich stadials and Dansgaard/Oeschger…

551.7Atmospheric Sciencegeographygeography.geographical_feature_categoryStable isotope ratio550.28Last GlacialspeleothemsOcean currentPaleontologySpeleothemstable isotopesprecipitation reconstructionOceanographyOceanographyHeinrich stadialsPrecipitationGlacial periodGeologyDansgaard/Oeschger cycles
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Thermomineral waters of Greece: geochemical characterization

2020

75 °C). In terms of pH most results vary from 5.5 to 823 °C) ii) warm (23 40 °C) iii) thermal (40 75 °C) and iv) hyperthermal (&gtfew springs show either very low pH (&lt10) proposing serpentinization processes. Regarding TDS concentrations collected waters can be subdivided into low salinity (up to 1.5 g/L) brackish (up to 20 g/L) and saline (up to 43 g/L). The medium high salinities can be justified by mixing with sea water and/or strong waterrock interaction processes. Isotope composition of O and H ranges from 12.7 to +2.7 ‰ SMOW and from 91 to +12 ‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O possibly related to high temperature waterrock interaction processes. Carbon dioxide (18 997000 μmol/mol) or N2 (1100 989000 μmol/mol) or CH4 (&ltMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary volcanism and in continental basins characterised by elevated heat flow. Moreover the majority of them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is often brackish to saline due to marine intrusion into costal aquifer. In the present study almost 300 thermal and cold mineral water samples were collected along the Hellenic territory with their physicochemical parameters (temperature pH electrical conductivity and Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally gases found either in free or dissolved phase were sampled. Both water and gas samples were analysed at the INGVPa laboratories for major ions (Ion Chromatography) silica (Inductively Coupled Plasma Optical Emission Spectrometry) chemical composition of free and dissolved gases (Gas Chromatography) water isotopes (O and H) and carbon and helium isotopes of free and dissolved gases (Mass Spectrometry). The temperature of the investigated waters ranges from 6.5 to 98°C pH from 1.96 to 11.98 whilst Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter waters can be divided into four groups: i) cold (&lt0.5 913000 μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from 20.1 to +8.5 ‰ whilst the isotope ratio of He from 0.21 to 6.71 R/RA.4) suggesting interaction with H2Srich gases or very high pH values (&gtSettore GEO/08 - Geochimica E Vulcanologia
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Stable isotopes covering 96-7 ka BP from stalagmite CM (Santo Tomas Cave, Cuba)

2020

We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Stable isotope samples were micromilled at a resolution of 0.10-0.33mm, and measured using an IRMS equipped with a Gasbench. Line scans of Element/Calcium ratios of the speleothem were measured by laser ablation ICPMS and were reduced to the resolution of the stable isotope records.

AGESpeleothem sampleδ13C stackedδ13CEarth System Researchpaleoclimatologyδ18O stackedstackedCentral Americaδ18OMass spectrometer DeltaPlusXL coupled to a Gasbench IIspeleothemStable isotopes
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Digestion and absorption rates of [3H]-oleic acid and [14C]-triolein do not differ in rats fed heated (-) and (+) gossypol cottonseed and soybean flo…

1998

This study was conducted to compare in vivo the acute effects of heated (+) and (-) gossypol cottonseed flours with those of soybean flour on lipid digestion and absorption in growing rats. Rats were fed by gastric intubation mixed [ 3 H]-oleic acid and [ 14 C]-triolein with heated flours or without flour (control). Lipid digestion and absorption were determined for 6 h after meal intubation. Both radioactivities recovered in gastrointestinal tract were significantly higher in rats fed (+) gossypol cottonseed flour than in all other groups. The majority of both recovered radioactivities was found in stomach contents, then in stomach wall and finally in intestinal wall. The distribution of b…

Absorption (pharmacology)MaleHot TemperatureCottonseed OilMedicine (miscellaneous)BiologyFatty Acids NonesterifiedTritiumCottonseedchemistry.chemical_compoundAnimalsTrioleinFood scienceCarbon RadioisotopesIntestinal MucosaRats WistarIntubation GastrointestinalTriglyceridesGastrointestinal tractNutrition and DieteticsfungiGossypolfood and beveragesRatsOleic acidKineticschemistryBiochemistryIntestinal AbsorptionGossypollipids (amino acids peptides and proteins)DigestionSoybeansDigestionLipid digestionTrioleinOleic AcidThe Journal of nutrition
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Ag11(SG)7 : A New Cluster Identified by Mass Spectrometry and Optical Spectroscopy

2014

We report a one-step and high yield synthesis of a red-luminescent silver cluster with the molecular formula, Ag11(SG)7 (SG: glutathionate) via reduction of silver ions by sodium borohydride in the presence of the tripeptide, glutathione (GSH). The as-prepared cluster shows prominent absorption features at 485 and 625 nm in its UV-vis absorption spectrum. Aging of the as-prepared cluster solution led to the disappearance of the 625 nm peak, followed by broadening of the 485 nm peak to give three maxima at ?487, 437, and 393 nm in its absorption spectrum. These peaks remain unchanged even after polyacrylamide gel electrophoresis (PAGE), where a single band was observed confirming high purity…

Absorption spectroscopyta114Electrospray ionizationAnalytical chemistryMass spectrometryAbsorption spectra; Density functional theory; Electrodeposition; Electromagnetic wave absorption; Electrophoresis; Electrospray ionization; Isotopes; Light absorption; Mass spectrometry; Metal ions; Potable water; Spectrometry; Ultraviolet spectroscopy; Absorption features; Electrospray ionization mass spectrometry; High yield synthesis; Molecular formula; Optical spectroscopy; Polyacrylamide gel electrophoresis; Sodium boro hydrides; UV-VIS absorption spectra; Absorption spectroscopySurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsIonSodium borohydridechemistry.chemical_compoundGeneral EnergyUltraviolet visible spectroscopychemistryPhysical and Theoretical ChemistryAbsorption (electromagnetic radiation)Spectroscopyta116Journal of Physical Chemistry C
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A radiometric and petrographic approach to risk assessment at Alte Madonie Mounts region (Sicily, Italy)

2013

The main goal of this work was to assess the radiological hazard at Alte Madonie Mounts region (north-central Sicily, Italy) in response to rumours of an increase in the incidence of cancer in this area. A correlation between the natural radionuclide contents and the petrographic features of the soil and rock samples was also evaluated. A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in 'Marinelli' beakers for 20 d prior to measurement to ensure that a radioactive equilibrium between (226)Ra and (214)Bi had been reached. A gamma-ray spectrometer was used to quantify the radioactivity concentrations. To determine (238)U and (232)Th activities, the…

ActiniumSettore ING-IND/20 - Misure E Strumentazione NucleariMineralogychemistry.chemical_elementRisk AssessmentNuclear physicsPetrographyRadiation MonitoringBackground RadiationSoil Pollutants RadioactiveRadiology Nuclear Medicine and imagingRadiometrySicilyRadioisotopesRadionuclideRadiationGeographyRadiological and Ultrasound TechnologyCarbonate radiaoctivity petrographyThoriumSettore GEO/07 - Petrologia E PetrografiaPublic Health Environmental and Occupational HealthThoriumGeneral MedicineSecular equilibriumUraniumSpectrometry GammaLinear relationshipchemistrySoil waterLinear ModelsPotassiumUraniumEnvironmental scienceRadiometric datingBismuthRadiumRadiation Protection Dosimetry
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The identification of vicinally substituted cyclohexane isomers in their mixtures by 1H and 13C NMR spectroscopy.

2000

The radical addition reactions of organobromine compounds, XBr (X = CH2COOMe, PhCH2, CHBr2 and CCl3) with cyclohexene afforded mixtures of cis/trans isomer pairs of 1-X-2-Br-cyclohexanes. In addition to benzyl benzoyloxy derivatives are formed also, when benzoyl peroxide is used as an initiator. Owing to the great difficulties in separating these cis/trans isomer pairs, they are identified directly in their mixtures by NMR spectroscopy. In addition to one-dimensional (ID) 1H, proton decoupled 13C and DEPT-135, also two-dimensional (2D) 13C-13C INADEQUATE as well as 1H-13C HMQC experiments have been used in assigning the signals of each compound in their mixtures. The identification of each …

Addition reactionCarbon IsotopesMagnetic Resonance SpectroscopyCyclohexaneStereochemistryCyclohexeneMolecular ConformationStereoisomerismStereoisomerismBenzoyl peroxideNuclear magnetic resonance spectroscopyTritiumMedicinal chemistryAtomic and Molecular Physics and OpticsAnalytical Chemistrychemistry.chemical_compoundchemistryCyclohexanesmedicineMolecular orbitalInstrumentationSpectroscopyCis–trans isomerismmedicine.drugSpectrochimica acta. Part A, Molecular and biomolecular spectroscopy
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Contribution of thallium-201-SPECT to the grading of tumorous alterations of the brain

1992

Single photon emission computed tomography (SPECT) with thallium-201-chloride (201Tl) was used in 22 patients to assess the grade of malignancy of brain tumors. Low- and high-grade malignant gliomas could be well differentiated by calculating the Grade Index (GI), i.e., 201Tl uptake in the tumor area relative to a contralateral brain region. Low-grade gliomas (WHO-grade I-II) usually showed a GI of1.5. Tumors classified histologically as high-grade malignant (WHO-grade III-IV) had GI values greater than 1.42 and a mean value of 1.89. Until labelled amino-acid tracers for gamma-cameras become commercially available, thallium-201 brain-SPECT can provide an independent and complementary method…

AdenomaAdultMalemedicine.medical_specialtychemistry.chemical_elementAstrocytomaSingle-photon emission computed tomographyMalignancyDiagnosis DifferentialMeningeal NeoplasmsmedicineHumansPituitary NeoplasmsGrading (tumors)AgedNeoplasm StagingTomography Emission-Computed Single-Photonmedicine.diagnostic_testBrain Neoplasmsbusiness.industryBrainGliomaNeuroma AcousticGeneral MedicineMiddle Agedmedicine.diseaseThallium RadioisotopeschemistryPositron emission tomographyThalliumFemaleSurgeryNeurology (clinical)NeurosurgeryMeningiomabusinessNuclear medicineNeurosurgical Review
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Toxic adenoma and papillary thyroid carcinoma in a patient with Graves' disease.

1999

A case of a very rare association of toxic adenoma and papillary carcinoma with Graves’ disease is presented. A 34-year-old woman developed Graves’ disease with mild ophthalmopathy. An ultrasound revealed diffuse thyroid enlargement with a hypoechoic pattern and a hypoechoic nodule with regular edges of 1.6 cm in diameter at the lower pole of the left lobe. A thyroid 131I scintiscan showed a diffuse and homogeneous 131I distribution. The 131I uptake (RAIU) was elevated. One year later, while still on a low dose of methimazole, the patient had a recurrence of hyperthyroidism following an iodine load from a contrast agent. A further thyroid ultrasound confirmed the previously described patter…

AdenomaAdultendocrine systemPathologymedicine.medical_specialtyendocrine system diseasesAdenomaEndocrinology Diabetes and MetabolismGraves' diseasemedicine.medical_treatmentThyroid carcinomaIodine RadioisotopesEndocrinologyAntithyroid AgentsCarcinomamedicineHumansNeoplastic transformationThyroid NeoplasmsUltrasonographyMethimazolebusiness.industryThyroidThyroidectomyNodule (medicine)medicine.diseaseCarcinoma PapillaryGraves DiseaseThyroxinemedicine.anatomical_structureThyroidectomyFemalemedicine.symptombusinessJournal of endocrinological investigation
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A computational model of postprandial adipose tissue lipid metabolism derived using human arteriovenous stable isotope tracer data

2019

Given the association of disturbances in non-esterified fatty acid (NEFA) metabolism with the development of Type 2 Diabetes and Non-Alcoholic Fatty Liver Disease, computational models of glucose-insulin dynamics have been extended to account for the interplay with NEFA. In this study, we use arteriovenous measurement across the subcutaneous adipose tissue during a mixed meal challenge test to evaluate the performance and underlying assumptions of three existing models of adipose tissue metabolism and construct a new, refined model of adipose tissue metabolism. Our model introduces new terms, explicitly accounting for the conversion of glucose to glyceraldehye-3-phosphate, the postprandial …

Adipose Tissue/metabolismDIETARY FATTY-ACIDSmedicine.medical_treatmentFatty Acids NonesterifiedBiochemistry0302 clinical medicineEndocrinologyModelsInsulinGlucose/metabolismBiology (General)Organic CompoundsFatty AcidsChemical ReactionsPostprandial Period/physiologyPostprandial PeriodLipidsPostprandialBloodComputational Theory and MathematicsAdipose TissueModeling and SimulationPhysical Sciencesmedicine.medical_specialtyQH301-705.5LipolysisCarbohydratesLIPOPROTEIN-LIPASECarbohydrate metabolism03 medical and health sciencesNEFASDG 3 - Good Health and Well-beingGeneticsLipolysisHumansComputer SimulationMolecular BiologyEcology Evolution Behavior and SystematicsBlood Glucose/metabolismArteriovenous AnastomosisChemical CompoundsBiology and Life SciencesComputational BiologyComputational Biology/methodsmedicine.diseaseLipid MetabolismBiologicalHormonesLipid Metabolism/physiology030104 developmental biologyEndocrinologyBiological TissueGlucoseMOBILIZATION030217 neurology & neurosurgery0301 basic medicineGlycerolBlood GlucosePhysiologyPATHOGENESISAdipose tissueLipids/physiologySDG 3 – Goede gezondheid en welzijnVoeding Metabolisme en GenomicaGlucose MetabolismIsotopesMedicine and Health SciencesMetabolitesINSULIN-RESISTANCEEcologyChemistryHydrolysisMonomersMonosaccharidesArteriovenous Anastomosis/metabolismMetabolism and GenomicsBody FluidsChemistryFatty Acids/metabolismMetabolisme en GenomicaCarbohydrate MetabolismNutrition Metabolism and GenomicsFatty Acids Nonesterified/metabolismAnatomyResearch ArticleInsulin/metabolismINHIBITIONWEIGHT-LOSSModels BiologicalBlood PlasmaMECHANISMSCellular and Molecular NeuroscienceInsulin resistanceVoedingInternal medicinemedicineLife ScienceNonesterified/metabolismNutritionDiabetic EndocrinologyInsulinOrganic ChemistryLipid metabolismECTOPIC FATPolymer ChemistryMetabolism
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