Search results for "carbon (C)"
showing 10 items of 156 documents
Storage and release of fossil organic carbon related to weathering of sedimentary rocks
2007
International audience; The biogeochemical carbon cycle, which plays an undeniable role in global climate change, is defined both by the size of carbon reservoirs (such as the atmosphere, biomass, soil and bedrock) and the exchange between them of various mineral and organic carbon forms. Among these carbon forms, fossil organic carbon (FOC) (i.e., the ancient organic matter stored in sedimentary rocks) is widely observed in modern environments but is not included in the supergene carbon budget. Using a digitized map of the world and an existing model of CO2 consumption associated with rock weathering, we establish the global distribution of FOC stored in the first meter of sedimentary rock…
Novel virocell metabolic potential revealed in agricultural soils by virus-enriched soil metagenome analysis
2021
International audience; Viruses are now recognized as important players in microbial dynamics and biogeochemical cycles in the oceans. Yet, compared with aquatic ecosystems, virus discovery in terrestrial ecosystems has been challenging partly due to the inherent complexity of soils. To expand our understanding of soil viruses and their putative contributions to soil microbial processes, we analysed metagenomes of community-level virus-enriched suspensions by tangential flow filtration obtained from two French agricultural soils. We found viral sequences representing a total of 239 viral operational taxonomic units that corresponded to 29.5% of the mapping reads in the metagenomic datasets.…
Fracture Toughness and Bridging Law of 3D Woven Composites
2003
ABSTRACT In the paper, the methodology of measuring G 1 c by using DCB specimens in the presence of large-scale bridging is adapted for investigating the delamination in 3D woven composites. The main novelties introduced in the DCB testing concern a) the loading device, b) the specimen geometry, c) the measurement scheme, and d) the determination of G 1 c and the bridging law from experimental data. The geometry-independent material characteristic G 1c as a function of the initial crack opening displacement (ICOD) is introduced. Typical values of the delamination fracture toughness of 3D glass and carbon composites are presented.
What You Should Know About Carbon Markets
2008
Since the entry into force of the Kyoto Protocol, carbon trading has been in continuous expansion. In this paper, we review the origins of carbon trading in order to understand how carbon trading works in Europe and, specifically, the functioning of the European Union Emission Trading Scheme (EU ETS) and the workings of several spot, futures and options markets where European Union Allowances are traded. As well, the linking of the EU ETS with the other United Nations carbon markets is also studied.
Assessment for the mean value total dressing method: Comparison with coupled cluster including triples methods for BF, NO+, CN+, C2, BeO, NH3, CH2, H…
1997
Limited previous experience with the mean value total dressing (MVTD) method had shown that MVTD energies for closed shell systems are generally better than CCSD(T) ones compared to FCI. The method, previously published as total dressing 2′(td-2′), is based on the single reference intermediate Hamiltonian theory. It is not a CC method but deals in a great part with the same physical effects that CC methods that incorporate amplitudes of triples such as CCSDT or its CCSDT-1n approaches. A number of test calculations comparing to diverse CC methods, as well as FCI and experiment when available, have been performed. The tests concern equilibrium energies in NH3 and CH2, equilibrium energies an…
Compensatory water effects link yearly global land CO2 sink changes to temperature
2017
Large interannual variations in the measured growth rate of atmospheric carbon dioxide (CO2) originate primarily from fluctuations in carbon uptake by land ecosystems1–3. It remains uncertain, however, to what extent temperature and water availability control the carbon balance of land ecosystems across spatial and temporal scales3–14. Here we use empirical models based on eddy covariance data15 and process-based models16,17 to investigate the effect of changes in temperature and water availability on gross primary productivity (GPP), terrestrial ecosystem respiration (TER) and net ecosystem exchange (NEE) at local and global scales. We find that water availability is the dominant driver of…
Novel Lipid and Polymeric Materials as Delivery Systems for Nucleic Acid Based Drugs
2015
Nucleic acid based drugs (NADBs) are short DNA/RNA molecules that include among others, antisense oligonucleotides, aptamers, small interfering RNAs and micro-interfering RNAs. Despite the different mechanisms of actions, NABDs have the ability to combat the effects of pathological gene expression in many experimental systems. Thus, nowadays, NABDs are considered to have a great therapeutic potential, possibly superior to that of available drugs. Unfortunately, however, the lack of effective delivery systems limits the practical use of NABDs. Due to their hydrophilic nature, NABDs cannot efficiently cross cellular membrane; in addition, they are subjected to fast degradation by cellular and…
Preventing early age chloride migration into low-carbon concrete
2019
The use of substituting cementitious materials (SCMs) to produce low-carbon concrete is escalating. This contributes to reducing the anthropogenic emission of CO2, and to reduce harmful temperature gradients during cement hydration in massive structures. Mature low-carbon concretes are known to perform well on both strength and durability. However, the maturity process is slow compared to that of standard concrete. Structures made from low-carbon concrete are subject to penetration of agents like chloride at early age, accelerating degrading processes. Chloride penetration is a major problem especially to infrastructure, due to seawater proximity and the use of de-icing agents. Solutions fo…
53 Human bio-monitoring of epoxy resins and hardeners in the production of rotor: blades
2018
Introduction In a small company producing rotor blades for aviation from carbon composites, epoxy resins based on Novolac and isophorone diamine as hardener are used. Both compounds can be absorbed via skin contact and were shown to be strong skin sensitizers. As a part of risk assessment, the industrial physician prompted a biological monitoring to determine the internal exposure of the workers. Methods 6 workers were identified with potential contact to the hardener and resin. We have collected pre- and post-shift urine samples at the beginning and mid of the work week and analysed them for the concentration of isophoronediamine and bisphenol-f-diglycidylethermetabolites as biomarker for …
Intraday Price Dynamics between EUAs and CERs in the European Carbon Futures Market
2011
We provide the first intraday analysis on the contribution to price discovery of two emissions carbon credits: European Union Allowances (EUAs) and Certified Emission Reductions (CERs). We find that EUAs lead price discovery but CERs play a growing role and, therefore, should not be ignored.