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[en] We tend to believe that in ancient times the scientific knowledge were scarce and sometimes arises something in history which exceeds our expectations and denies it. This is the case of the protagonist of this article, the Antikythera mechanism, an instrument that has allowed us to better understand those prodigious minds of our ancestors. (Author)
[en] Most stable isotope workers believe that the delta13C values of carbonatites, kimberlites and diamonds (-5 to -70/00 PDB) represent the isotopic ratio of deep-seated 'juvenile' carbon. There are, however, some findings that disagree with this hypthesis: 1) Trace amounts of reduced carbon found in all igneous rocks have delta13C values around -250/00. Lunar rocks, except dust and fines, show quite negative delta13C values. 2) The data of Clayton et al. (1976) suggest that the earth and the moon have a common origin. 3) Where it is possible to sample CO2 over liquid lava delta13C values between -18 and -240/00 have been obtained. Similar values have been observed in CO2 inclusions in evaporites neighbouring basaltic dikes. 4) CO2 from fluid inclusions in olivine nodules found within basaltic rocks also shows light delta13C values. The 'primary' carbonic fluid from fluid inclusions in granulite facies rocks appears to have delta13C values around -150/00 or even lighter up to -200/00. During the late stages of retrograde metamorphism an enrichment in 13C seems to occur, resulting in delta values between -5 and -70/00.(auth.)
[en] The purpose of this paper is to establish a set of steps for helping companies to create a Green Supply Chain Strategy based on the reduction of their carbon footprint. The aim is to put forward a simple guideline that companies can follow and guide them in achieving their carbon emission targets, as well as obtaining attractive supply chain savings. Design/methodology/approach: Based on a literature review and benchmarking this paper proposes a methodology based on three pillars: 1) Corporate Carbon Strategy; 2) Carbon emission roadmap; and 3) Implementation and tracking. Analytic Hierarchy Process (AHP) techniques were used in order to create a green strategy and support the decision-making processes to select the most interesting alternatives for carbon emission reduction and supply chain savings. The supply chain of a metallurgical company is used to illustrate the case study where the proposed methodology is used. The criteria used for the carbon alternatives selection was based on three factors: 1) the supply chain cost of the alternative; 2) carbon emission impact in terms of CO2 tonnes; and 3) marketing effect. Findings: The paper identifies some specific steps for developing a Green Supply Chain Strategy. The case study developed, demonstrates the importance of following a proper methodology based on a set of steps, it also demonstrates that some alternatives focus on improving the supply chain, such as the facilities location, can also improve the key performance indicator related with carbon emission. Originality/value: The study provides guidance for manufacturing companies in implementing their Green Supply Chain Strategy.
[en] Clathrate hydrates have been found to occur naturally, and have been extensively studied due to their important industrial applications, such as the storage of the CO_2 from the atmosphere and control climate change. Thus, quantitative understanding of physical and chemical properties, as well as the factors that control the formation of CO_2 hydrates, on both macroscopic and microscopic levels is essential in several areas of physical science. (paper)
[en] An experimental strategy for determining the coil–globule transition parameters of a polymer chain in supercritical carbon dioxide has been developed on the basis of a gas-dynamic model of the expansion of a pulse jet of a van der Waals gas . Taking into account the behavior of CO2 in the near-critical region and isentropic conditions of the jet expansion process, starting conditions that arise in the nozzle and correspond to the proposed model are determined. The design of the experiment (geometrical and size parameters of the key components of the equipment, pulse valve duration, etc.) is developed. Possible options for carrying out the experiment and processing the experimental data are discussed. Calculation procedures for the case corresponding to the experimental conditions described in [2, 3] are given as an example.
[en] Carbon capture and storage (CCS) technologies are a cornerstone for reducing CO_2 emissions from energy and energy-intensive industries. Among the various CCS technologies, solid sorbent looping systems are considered to be potentially promising solutions for reducing CO_2 capture energy penalty. We present an evaluation module for a carbonator with sorbent looping cycle to calculate the carbonation efficiency. The module incorporates a simple sorbent activity model, and the solid/gas balances are constructed by assuming simple reactor mixing quality. By conducting simulations, we examine the variation in the carbonation efficiencies as a function of the sorbent looping operation factors and discuss an optimum operating strategy
[en] Solubility data of carbon dioxide (CO_2) in two pyrrolidinium-based ionic liquids: 1-butyl-1-methylpyrrolidinium dicyanamide ([bmpyr][dca]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpyr] [Tf_2N]) are presented at pressures up to about 30MPa and temperatures from 303..2 K to 343.2 K. The solubility was determined by measuring bubble or cloud point pressures of mixtures of CO_2 and ionic liquid using a high-pressure equilibrium apparatus equipped with a variable-volume view cell. The CO_2 solubility in the ionic liquid in terms of the mole fraction or the molality increased with the increase of the equilibrium pressure at a given temperature, but decreased with the increase of temperature at a given pressure. At a given temperature, the mole fraction of CO_2 dissolved in the ionic liquid increased rapidly as pressure increased. CO_2 solubility in the mole fraction almost reached saturation around 0.65 for [bmpyr][dca] and around 0..8 for [bmpyr][Tf_2N], respectively. The experimental data for the CO_2+ionic liquid systems were correlated using the Peng-Robinson equation of state (PR-EoS). The mixing rules of the Wong-Sandler type rather than the classical mixing rules of the van der Waals type were coupled with the PR-EoS. The resulting modeling approach proved to be able to correlate the CO_2 solubilities in aforementioned ionic liquids over the aforementioned range of temperature and pressure within 5% average deviations