Search results for " CO2."
showing 10 items of 160 documents
Andamento stagionale del flusso di emissione di CO2 dal suolo in risposta al contenuto di umidità all'interno di un agroecosistema mediterraneo
2014
Total soil respiration as the sum of two biotic component, autotrophic and heterotrophic respiration, is influenced by various environmental factor, in particular soil temperature and soil moisture. In arid and semi arid regions, soil moisture is a major driver of soil respiration during periods of drought stress. Hence, the aim of this work was to evaluate the effect of soil moisture on soil CO2 efflux. Measurements were made every two weeks between January 2008 and June 2010 using a portable soil respiration instrument fitted with a soil respiration chamber (IRGA) CIRAS 1 (PP Systems, Hitchin, UK).The Simultaneously with soil respiration measurements, soil temperature (T) and soil volumetri…
Use of supercritical CO2 and N2 as dissolved gases for the atomization of ethanol and water
2012
Supercritical dissolved gas atomization (SDGA) is an atomization process in which a gas at temperatures and pressures above the critical point is used as the atomizing medium. The concept of SDGA has been applied mainly using CO 2 as atomizing gas in various processes developed for the production of fine particles of pharmaceuticals, polymers, and chemical products and for the atomization of fuels. In this work, SDGA, using ethanol and water as the liquids to be atomized, has been experimentally studied. The spray characteristics, in terms of droplet size and distribution, have been investigated using a laser diffraction analyzer. Ethanol has been chosen due to the large miscibility with CO…
The instability of the adjusted and unadjusted environmental Kuznets curves
2006
We test the stability of the unadjusted and adjusted environmental Kuznets curves (EKCs). Our results provide evidence in favour of a theoretically funded "adjusted EKC hypothesis" in which the impact of per capita GDP on CO2 emissions is evaluated conditionally to the effects of the industry mix and of the energy-supply infrastructure. In this specification, the shape of the GDP-CO2 relationship appears quite sensitive to changes in the estimation period. In the final part of the paper, signs and dynamics of fixed effects of individual countries in different specifications are interpreted as measures of virtuous or vicious of environmental behaviour. © 2006 Elsevier B.V. All rights reserve…
Duvalo “Volcano” (North Macedonia): A Purely Tectonic‐Related CO 2 Degassing System
2022
Duvalo “volcano” is a site of anomalous geogenic degassing close to Ohrid (North Macedonia) not related to volcanic activity, despite its name. CO2 flux measurements made with the accumulation chamber (321 sites over ∼50,000 m2) showed fluxes up to nearly 60,000 g m-2 d-1, sustaining a total output of ∼67 t d-1. Soil gas samples were taken at 50 cm depth from sites with high CO2 fluxes and analyzed for their chemical and isotope composition. The gas is mainly composed by CO2 (> 90%) with significant concentrations of H2S (up to 0.55 %) and CH4 (up to 0.32 %). The isotope compositions of He (R/RA 0.10) and of CO2 (δ13C ∼0‰) exclude significant mantle contribution, while δ13C-CH4 (∼ -35‰) …
Photocatalytic membranes based on TiO2 catalysts and fluorinated polymers for CO2 conversion
2015
In this work, prepared TiO2–Nafion™-based membranes were used in a photocatalytic membrane reactor, operated in continuous mode, for converting CO2 to methanol.
Pedogenesis and carbon sequestration in transformed agricultural soils of Sicily
2021
The increasing atmospheric CO2 concentration is a consequence of human activities leading to severe environmental deteriorations. Techniques are thus needed to sequester and reduce atmospheric carbon. One of the proposed techniques is the transformation or construction of new soils into which more organic carbon can be sequestered and CO2 be consumed by increased weathering. By using a chronosequence of new and transformed soils on crushed limestone (0–48 years) in a Mediterranean area (Sicily), we tried to quantify the amount of organic carbon that could be additionally sequestered and to derive the corresponding rates. A further aim was to trace chemical weathering and related CO2 consump…
The Constraints of Vehicle Range and Congestion for the Use of Electric Vehicles for Urban Freight in France
2015
The 9th International Conference on City Logistics, Tenerife, Espagne, 17-/06/2015 - 19/06/2015; Electric vehicle is a solution to reduce pollutant emissions from road urban freight. This paper assesses the potential CO2 reduction by transferring urban freight from diesel to electric vehicles while simultaneously looking at the two main technical constraints: electric vehicle range and the impact on congestion linked to change diesel heavy duty vehicles (with a load up to 25 tons) to much smaller electric vehicles. The data used has been computed from a survey (ECHO) that describes in details a very large sample of French shipments. Two scenarios were set up, which differ mainly by the type…
Tratamiento de los carcinomas epidermoides orales y orofaringeos mediante láser de CO2
2004
Introducción: El efecto de la amplia longitud de onda del láser de CO2 es la vaporización térmica de los tejidos, consiguiendo una máxima concentración de energía con una mínima penetración en los mismos. En el campo de la cirugía oral generalmente se emplea para el tratamiento de los pequeños tumores mucosos de la cavidad oral y la orofaringe, por la escasa morbilidad que produce y la ausencia de necesidad reconstructiva del defecto creado. Objetivo: Analizar la evolución postoperatoria, en los pacientes tratados por carcinomas epidermoides orales y orofaringeos, tras la resección mediante láser de CO2. Compararla con la de los pacientes tratados mediante métodos quirúrgicos convencionales…
Intermedios Reactivos en CO2sc
2015
Dióxido de carbono supercrítico (CO2sc) es un medio de reacción alternativo que se considera similar a n-pentano o tetracloruro de carbono. Los parámetros de polaridad caracterizan a CO2sc como apolar (ETN(200 bar) = -0.053), con baja permitividad eléctrica ((200 bar) = 1.5) y sin capacidad para aceptar puentes de hidrógeno ( = 0 ), aunque estas características contrastan con su capacidad disolvente frente a determinados sustratos, particularmente compuestos fluorados, y sus interacciones con los grupos funcionales básicos de moléculas orgánicas, como grupos carbonilo o hidroxilo. El estudio de reacciones orgánicas fuertemente sensibles al disolvente en CO2sc descrito en el presente traba…
A solar photothermo-catalytic combined process for the VOCs combustion and the subsequent CO2 valorization using noble metal-free catalysts
2023
We here investigated a solar photothermo-catalytic combined process where the toluene (as volatile organic compound model) was first oxidized to CO2 which was subsequently converted into solar fuels in a second reactor. For this aim two noble-metal free catalytic systems were used, namely MnOx-ZrO2, which gave the best results for the toluene removal, and brookite TiO2-CeO2 mixed oxides which were the most efficient in the subsequent CO2 conversion. This latter reaction was further improved by the addition of small amounts of copper-based materials on brookite-ceria, acting as co-catalysts. The key point for both the examined reactions was the synergism between the thermocatalytic and the p…