Search results for " Carbon Dioxide"

showing 10 items of 200 documents

Lidar sounding of volcanic plumes

2013

ABSTRACT Accurate knowledge of gas composition in volcanic plumes has high scientific and societal value. On the one hand, it gives information on the geophysical processes taking place inside volcanos; on the other hand, it provides alert on possible eruptions. For this reasons, it has been suggested to monitor volcanic plumes by lidar. In particular, one of the aims of the FP7 ERC project BRIDGE is the measurement of CO 2 concentration in volcanic gases by differential absorption lidar. This is a very challenging task due to the harsh environment, the narrowness and weakness of the CO 2 absorption lines and the difficulty to procure a suitable laser source. This paper, after a review on r…

010504 meteorology & atmospheric sciencesAerosol load01 natural sciencesVolcanic plume010309 opticsVolcanic Gases0103 physical scienceseventGas compositionAbsorption (electromagnetic radiation)Water vapor0105 earth and related environmental sciencesRemote sensingevent.disaster_typeLidargeographygeography.geographical_feature_categoryAerosolDepth soundingLidarCarbon dioxideVolcano13. Climate actionAerosol load; Carbon dioxide; Differential absorption; Lidar; Volcanic plumes; Water vaporDifferential absorptionWater vaporGeologyLidar Technologies, Techniques, and Measurements for Atmospheric Remote Sensing IX
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Functional, textural and sensory properties of dry pasta supplemented with lyophilized tomato matrix or with durum wheat bran extracts produced by su…

2016

A study was carried out to produce functional pasta by adding bran aqueous extract (BW) and bran oleoresin (BO) obtained using ultrasound and supercritical CO2, respectively, or a powdery lyophilized tomato matrix (LT). The bioactive compounds, hydrophilic and lipophilic antioxidant activity (HAA and LAA) in vitro, were evaluated. BW supplementation did not improve antioxidant activity, whilst LT pasta showed unconventional taste and odor. BO pasta had good levels of tocochromanols (2551 μg/100 g pasta f.w.) and carotenoids (40.2 μg/100 g pasta f.w.), and the highest HAA and LAA. The oleoresin altered starch swelling and gluten network, as evidenced by scanning electron microscopy, therefor…

0301 basic medicineAntioxidantGlutensStarchmedicine.medical_treatmentAntioxidantsGreen extraction technologieAnalytical Chemistry03 medical and health scienceschemistry.chemical_compound0404 agricultural biotechnologySolanum lycopersicummedicineFood scienceOleoresinCarotenoidTocochromanolTriticumCarotenoidchemistry.chemical_classification030109 nutrition & dieteticsSupercritical carbon dioxideBranPlant Extractsfood and beveragesStarch04 agricultural and veterinary sciencesGeneral MedicineCarotenoids040401 food scienceGlutenSupercritical fluidSettore AGR/02 - Agronomia E Coltivazioni ErbaceeSmellFunctional pastaPhenolicchemistryTriticum durumTasteFood FortifiedFood ScienceFood Chemistry
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Sterilization of macroscopic poly(l-lactic acid) porous scaffolds withdense carbon dioxide: Investigation of the spatial penetration of thetreatment …

2016

Abstract In this work the sterilization with dense carbon dioxide of poly( l -lactic acid) (PLLA) porous scaffolds intended for tissue engineering applications was investigated with the main objective of confirming the three-dimensional efficacy of the treatment and of analysing the scaffold properties after CO2 treatment. For this purpose the scaffold was contaminated with a conventional bacterium (Escherichia coli) and with spores (Streptomyces coelicolor), a species more fascinating and difficult to inactivate. Contamination was performed in such a way to soak the whole matrix with bacteria and spores. The effect of pressure and treatment time on the efficacy of the sterilization was eva…

0301 basic medicineScaffoldBiocompatibilityGeneral Chemical Engineering030106 microbiologyNanotechnology02 engineering and technology03 medical and health scienceschemistry.chemical_compoundTissue engineeringPhysical and Theoretical ChemistrySettore ING-IND/24 - Principi Di Ingegneria ChimicabiologyChemistryPenetration (firestop)Sterilization (microbiology)021001 nanoscience & nanotechnologyCondensed Matter Physicsbiology.organism_classificationDense carbon dioxide Sterilization PLLA scaffolds E. coli S. coelicolor BiocompatibilitySupercritical fluidLactic acidChemical engineering0210 nano-technologyBacteria
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CO2 flux emissions from the Earth's most actively degassing volcanoes, 2005-2015

2019

AbstractThe global carbon dioxide (CO2) flux from subaerial volcanoes remains poorly quantified, limiting our understanding of the deep carbon cycle during geologic time and in modern Earth. Past attempts to extrapolate the global volcanic CO2 flux have been biased by observations being available for a relatively small number of accessible volcanoes. Here, we propose that the strong, but yet unmeasured, CO2 emissions from several remote degassing volcanoes worldwide can be predicted using regional/global relationships between the CO2/ST ratio of volcanic gases and whole-rock trace element compositions (e.g., Ba/La). From these globally linked gas/rock compositions, we predict the CO2/ST gas…

0301 basic medicineVolcanologylcsh:MedicineAtmospheric sciencesCarbon cycleVolcanic Gases03 medical and health scienceschemistry.chemical_compound0302 clinical medicine[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanologyeventlcsh:Scienceevent.disaster_typeCarbon dioxide in Earth's atmospheregeographyMultidisciplinarygeography.geographical_feature_categoryAtmospheric carbon dioxidelcsh:RTrace elementFOS: Earth and related environmental sciencesVolcanologyGeochemistry030104 developmental biologyVolcanochemistry[SDU]Sciences of the Universe [physics]Carbon dioxideSubaerialEnvironmental scienceVolcanoeslcsh:Q030217 neurology & neurosurgeryvolcanic gas fluxes voclanoes
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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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Utilization of impedance spectroscopy to investigate the self-assembly behavior of amphiphiles soluble in supercritical carbon dioxide: Preliminary r…

2007

Abstract A mixture of CO 2 , water, methyl orange (MO) and Dynol 604 surfactant was analyzed at 309 K and 20 MPa simultaneously by impedance and UV–vis spectroscopy. A plot of the static dielectric constant as a function of the surfactant concentration was obtained using a suitable equivalent circuit to elaborate impedance data. Experimental points can be fitted by two different straight lines whose intersection occurs at about 0.13% (w/w) concentration of Dynol. When the surfactant concentration crossed the aforementioned value, a peak was detectable in the UV–vis spectrum at a wavelength range corresponding to the absorption of MO; absorbance of the peak increased with the surfactant conc…

AbsorbanceSupercritical carbon dioxidePulmonary surfactantChemistryGeneral Chemical EngineeringCritical micelle concentrationAnalytical chemistryMicroemulsionPhysical and Theoretical ChemistryCondensed Matter PhysicsSpectroscopySupercritical fluidDielectric spectroscopyThe Journal of Supercritical Fluids
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Design of nonionic surfactants for supercritical carbon dioxide

1996

Interfacially active block copolymer amphiphiles have been synthesized and their self-assembly into micelles in supercritical carbon dioxide (CO 2 ) has been demonstrated with small-angle neutron scattering (SANS). These materials establish the design criteria for molecularly engineered surfactants that can stabilize and disperse otherwise insoluble matter into a CO 2 continuous phase. Polystyrene- b -poly(1,1-dihydroperfluorooctyl acrylate) copolymers self-assembled into polydisperse core-shell-type micelles as a result of the disparate solubility characteristics of the different block segments in CO 2 . These nonionic surfactants for CO 2 were shown by SANS to be capable of emulsifying u…

AcrylateMultidisciplinarySupercritical carbon dioxideSANSMicelleSupercritical fluidSolventchemistry.chemical_compoundchemistrysupercritical-CO2AmphiphilemicelleCopolymerOrganic chemistrySolubility
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Effects of gender on resting leg blood flow: implications for measurement of regional substrate oxidation.

1998

Jensen, Michael D., Tu T. Nguyen, A. Hernández Mijares, C. Michael Johnson, and Michael J. Murray. Effects of gender on resting leg blood flow: implications for measurement of regional substrate oxidation. J. Appl. Physiol. 84(1): 141–145, 1998.—These studies were designed to examine whether the respiratory quotient (RQ) of leg tissue (primarily skeletal muscle) would increase to a greater degree in women than in men during meal ingestion. We found that mean leg and systemic RQ values were similar in men under both basal and fed conditions, whereas the agreement was poor in women. In women, leg RQ values tended to be greater than the systemic RQ, whereas splanchnic RQ values tended to be l…

AdultMaleLegSex CharacteristicsPhysiologyChemistryHemodynamicsCalorimetry IndirectBlood flowAnatomyCarbon DioxideSubstrate (marine biology)Lower limbOxygenRegional Blood FlowPhysiology (medical)Body CompositionHumansFemaleSplanchnic CirculationBlood carbon dioxideOxidation-ReductionJournal of applied physiology (Bethesda, Md. : 1985)
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Functionalization of CnH2n+2Alkanes: Supercritical Carbon Dioxide Enhances the Reactivity towards Primary Carbon-Hydrogen Bonds

2015

The functionalization of the primary sites of alkanes is one of the more challenging areas in catalysis. In this context, a novel effect has been discovered that is responsible for an enhancement in the reactivity of the primary C-H bonds of alkanes in a catalytic system. The copper complex Cu(NCMe) (=hydrotris{[3,5-bis(trifluoromethyl)-4-bromo]-pyrazol-1-yl}borate) catalyzes the functionalization of CnH2n+2 with ethyl diazoacetate upon inserting the CHCO2Et unit into C-H bonds. In addition, the selectivity of the reaction toward the primary sites significantly increased relative to that obtained in neat alkane upon using supercritical carbon dioxide as the reaction medium. This was attribu…

Alkanechemistry.chemical_classificationSupercritical carbon dioxideChemistryOrganic Chemistrychemistry.chemical_elementPhotochemistryCatalysisSupercritical fluidCatalysisInorganic Chemistrychemistry.chemical_compoundEthyl diazoacetateMoleculeReactivity (chemistry)Physical and Theoretical ChemistryCarbonChemCatChem
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Favoring alkane primary carbon-hydrogen bond functionalization in supercritical carbon dioxide as reaction medium

2019

The selectivity of a catalytic alkane functionalization process can be modified just changing the reaction medium from neat alkane to supercritical carbon dioxide (scCO2). A silica supported copper complex bearing an Nheterocyclic carbene ligand promotes the functionalization of carbon-hydrogen bonds of alkanes by transferring the CHCO2Et group from N2=CHCO2Et (ethyl diazoacetate, EDA). In neat hexane only 3% of the primary C-H bonds (ethyl heptanoate being the product) are functionalized in that manner, whereas the same reaction carried out in scCO2 provides a 30% yield in this linear ester. Such effect seems to be induced by an electronic density flux from the NHC ligand to the surroundin…

Alkanechemistry.chemical_classificationSupercritical carbon dioxideRenewable Energy Sustainability and the EnvironmentGeneral Chemical EngineeringAlkaneCarbon–hydrogen bond activation02 engineering and technologyGeneral Chemistry010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical sciencesCatalysisHexanechemistry.chemical_compoundchemistryEthyl diazoacetateCarbon dioxidePolymer chemistryEnvironmental Chemistry0210 nano-technologyCarbon-hydrogenCarbeneEthyl heptanoate
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