Search results for "O2"
showing 10 items of 1115 documents
The Impact of the China Foreign Trade on its Actual CO2 Emissions
2018
CO2 emissions are a global problem. This means that nothing or very little will change if only particular countries are involved. The purpose of this paper is the attempt to show the real CO2 emissions of the China as well as the impact of its trade on CO2 emissions in other countries in the world and in the EU in 2015. This study was conducted on the group of countries that are the major emitters of CO2 in the world including most of the EU members. Countries with negligible CO2 emissions were omitted. Actual CO2 emissions were achieved by applying the actual emission factor. This takes into account the transfer of CO2 in export products and services as well as those imported by particular…
Optimisation of Conditions for Extraction of Biologically Active Compounds from Common Bryophytes in Latvia / Latvijâ Augoðu Briofîtu Ekstrakcijas Ap…
2015
Abstract Bryophytes are the second largest taxonomic group in the plant kingdom. They contain a high number of biologically active compounds. Studies of their composition are important for understanding evolutionary processes in the plant kingdom. The aim of this study was to assess bryophyte secondary metabolite extraction options and to increase the yields of polyphenols and substances determining the free radical scavenging activity of bryophyte extracts. Similar studies have been conducted using higher plants as model organisms, but not using bryophytes. Comparison of five extraction methods (conventional, Soxhlet extraction, treatment with microwaves, ultrasound, and supercritical CO2 …
Les habitudes alimentaires des familles françaises pendant le confinement lié au COVID-19 : (comment) ont-elles changé ?
2021
La pandemie liee au COVID-19 a conduit la France a imposer un confinement strict, affectant les habitudes des familles dans de nombreux domaines Cette etude visait a evaluer les changements possibles dans les comportements alimentaires des enfants, les pratiques educatives parentales en matiere d'alimentation et les motivations d'achat des aliments, pendant le confinement par rapport a la periode avant confinement Pendant le confinement, les parents de 498 enfants âges de 3 a 12 ans (238 garcons ;M = 7,32 ;ET = 2,27) ont repondu a une enquete nationale en ligne comprenant les items issus de questionnaires valides (ex CEDQ, CEBQ, HomeSTEAD) Ils ont decrit leur situation et celle de l'enfant …
Aspectos medioambientales y biomédicos de la Química Supramolecular de azaciclofanos derivados de la piridina y el pirazol
2015
Basándonos en las pautas descritas para obtener receptores capaces de interaccionar con determinados sustratos, se ha sintetizado un gran familia de azaciclofanos de condensación [1+1] en los que se han utilizado diferentes cadenas poliamínicas. Además, los receptores presentan un anillo heterocíclico a modo de espaciador, que aporta rigidez al ciclo y al mismo tiempo átomos de union adicionales. En este caso, se han utilizado anillos de piridina y pirazol. Por su parte, trabajar con poliaminas, ofrece una serie de ventajas ya que son relativamente económicas, fáciles de modificar mediante rutas sintéticas, presentan una gran versatilidad a la hora de interaccionar con los sustratos en func…
The heterogeneity of the Mexican lithospheric mantle: Clues from noble gas and CO2 isotopes in fluid inclusions
2022
The abundance of mantle-derived rocks and lavas, in combination with its tectonic evolution, render Mexico a perfect laboratory to investigate the chemical and the isotopic heterogeneity of the lithospheric mantle. New data on the composition of noble gases and CO2in Mexican mantle xenoliths and lavas is reported. Our samples consist of six ultramafic nodules from the Durango Volcanic Field (DVF) and the San Quintin Volcanic Field (SQVF), monogenetic complexes belonging to the Mexican Basin and Range province; and four lavas from the Sierra Chichinautzin (SCN), a Quaternary monogenetic volcanic field located in the Mexican volcanic arc. Ne and Ar isotopes in fluid inclusions reveal mixing b…
Fragmentation du combustible nucléaire UO2 en environnement oxydant : Etude cinétique et phénoménologique
2006
Une des voies envisagées pour apporter de la flexibilité à la gestion du combustible UO2 usé/irradié est son entreposage à sec. Ce mode de gestion pose en particulier la question de la tenue du combustible en cas de scénario accidentel qui entraînerait la mise à l'air des pastilles de UO2. La cinétique d'oxydation et la phénoménologie de la fragmentation de UO2 entre 250 et 330°C ont été étudiées à partir de vieillissements sous O2 et sous air de monocristaux et de fragments de pastilles de combustible non irradiés. En environnement oxydant, l'initiation de la fissuration semble due à la relaxation des contraintes de traction induites par la contraction du réseau cristallin lors de la crois…
Possibility of using NiCo2O4 alloy as catalyst for fuel electrode of hydrazine fuel cell
2017
Szerokie stosowanie ogniw paliwowych ograniczone jest głównie wykorzystywaniem drogich katalizatorów. Wyeliminowanie platyny umożliwiłoby szeroką komercjalizację tych ogniw. Artykuł przedstawia analizę elektroutleniania hydrazyny na katalizatorze NiCo2O4. Jako elektrolit wykorzystano wodny roztwór KOH. Pomiarów dokonano potencjostatem. Wykazano możliwość elektroutleniania hydrazyny na katalizatorze NiCo2O4. W każdym przypadku (dla wszystkich stężeń hydrazyny i udziałów Co) proces elektroutleniania zachodził. Gęstość prądu wynosiła 15–35 mA/cm2 dla wszystkich koncentracji hydrazyny i elektrolitu. Gęstość prądu jest niewielka, jednak koszt uzyskania katalizatora jest znacznie niższy od kosztó…
Graphene films for gas sensing applications
2013
Gas detection at small concentrations is usually done using transition metal oxides. These semiconductors are, however, strongly dependent on parameters and conditions of growth and processing. Graphene attracts a big interest in science and technology due to its exceptional electric properties, and this truly 2-dimensional material has a great promise to be used as highly sensitive gas sensor. In this thesis, CVD and epitaxial graphene samples have been investigated in order to improve their sensitivity in gas sensing applications. The response of the sensor to different concentrations of detected gas was observed as a relative change of resistance of the sample. The aim of this study was …
Behavior of rare earth elements in an aquifer perturbed by CO2 injection: Environmental implications
2019
International audience; Three cubic-meters of CO2-saturated water was injected into a subsurface fractured aquifer in a post-mined area, using a push-pull test protocol. Groundwater samples were collected before and after CO2-injection to quantify geochemical changes. CO2-injection initially reduced the pH of water from 7.3 to 5.7, led to the enrichment of major ions (Ca2+, Mg2+, and alkalinity), and dissolved trace metals (including Fe, Mn, As, and Zn) in the groundwater. Rare earth elements (REE) and yttrium concentrations were also measured in these samples before and after CO2 perturbation, to evaluate their behavior. An enrichment of total Y plus REE (REY) occurred. REY fractionation w…
The emissions of CO2 and other volatiles from the world’s subaerial volcanoes
2019
AbstractVolcanoes are the main pathway to the surface for volatiles that are stored within the Earth. Carbon dioxide (CO2) is of particular interest because of its potential for climate forcing. Understanding the balance of CO2 that is transferred from the Earth’s surface to the Earth’s interior, hinges on accurate quantification of the long-term emissions of volcanic CO2 to the atmosphere. Here we present an updated evaluation of the world’s volcanic CO2 emissions that takes advantage of recent improvements in satellite-based monitoring of sulfur dioxide, the establishment of ground-based networks for semi-continuous CO2-SO2 gas sensing and a new approach to estimate key volcanic gas param…