Improved activity and stability of Ce-promoted Ni/γ-A1 2O3 catalysts for carbon dioxide reforming of methane

The CO2 reforming of CH4 was carried out over Ni catalysts supported on γ-Al2O3 and CeO 2-promoted γ-Al2O3. The catalysts were characterized by means of surface area measurements, TPR, CO2 and H2 chemisorption, XRD, SEM, and TEM. The CeO2 addition promoted an increase of catalytic activity and stability. The improvement in the resistance to carbon deposition is attributed to the highest CO2 adsorption presented by the CeO2 addition. The catalytic behavior presented by the samples, with a different CH4/CO2 ratio used, points to the CH4 decomposition reaction as the main source of carbon deposition.

Treatment of developmental defect of upper lip with carbon dioxide laser radiation (CO2): First surgical time

With the exception of the cleft lip, developmental defects (DD) of the lip are rare. The upper lip originates from the ectomesenchyme and is formed by the merging of the nasal medial and lateral processes with the maxillary process. Disturbances during this formation period can cause DD with functional and/or esthetic repercussions. We present a case of DD of the upper lip in a patient with a history of progressive growth of the left lateral portion of the upper lip that occurred from the time of birth until the age of 22 years. Clinical examination revealed hypertrophy of the area from the left philtral columns to the left commissure of the lip, extending the portion of the surface mucosa creating a flaccid and asymptomatic tissue mass. All other buccal structures appeared to be within normal limits and without any evidence of defects or deformities. In the surgical planning we decided to carry out corrective surgery in two phases. The first phase accomplished a conservative excision of the total abnormal labial tissue mass with a CO2 laser radiation (5 W in continuous mode, bunch diameter φ = 0.6 mm with a power density of 768 W/cm2 and fluency of 0.231 J/cm2) being careful to preserve the vermilion portion of the lip. Postsurgical clinical evaluations were done every three days until the skin sutures were removed and then every seven days until two months post surgery. While the entire mass of excessive tissue could not be completely removed, the removal of the excessive mucosal tissue produced a very good outcome relative to lip function, with a good esthetic result without scarring, and good tissue mobility. The results showed that the CO2 laser is an extremely useful instrument that can provide excellent control of the surgical field and allow for healing that produces excellent functional and esthetic results. © 2005 Taylor & Francis.

Carbon dioxide evaporation in a single microchannel

Despite its importance for designing evaporators and condensers, a review of the literature shows that heat transfer data during phase change of carbon dioxide is very limited, mainly for microchannel flows. In order to give a contribution on this subject, an experimental study of CO 2 evaporation inside a 0.8 mm-hydraulic diameter microchannel was performed in this work. The average heat transfer coefficient along the microchannel was measured and visualization of the flow patterns was conducted. A total of 67 tests were performed at saturation temperature of 23.3°C for a heat flux of 1800 W/(m2°C). Vapor qualities ranged from 0.005 to 0.88 and mass flux ranged from 58 to 235 kg/(m2s). An average heat transfer coefficient of 9700 W/(m2°C) with a standard deviation of 35% was obtained. Nucleate boiling was found to characterize the flow regime for the test conditions. The dryout of the flow, characterized by the sudden reduction in the heat transfer coefficient, was identified at vapor qualities around 0.85. Flow visualization results showed three flow patterns. For low vapor qualities (up to about 0.25), plug flow was predominant, while slug flow occurred at moderated vapor qualities (from about 0.25 to 0.50). Annular flow was the flow pattern for higher vapor qualities. Copyright © 2006 by ABCM.

Carbon dioxide emissions under different soil tillage systems in mechanically harvested sugarcane

Soil tillage and other methods of soil management may influence CO 2 emissions because they accelerate the mineralization of organic carbon in the soil. This study aimed to quantify the CO2 emissions under conventional tillage (CT), minimum tillage (MT) and reduced tillage (RT) during the renovation of sugarcane fields in southern Brazil. The experiment was performed on an Oxisol in the sugarcane-planting area with mechanical harvesting. An undisturbed or no-till (NT) plot was left as a control treatment. The CO2 emissions results indicated a significant interaction (p < 0.001) between tillage method and time after tillage. By quantifying the accumulated emissions over the 44 days after soil tillage, we observed that tillage-induced emissions were higher after the CT system than the RT and MT systems, reaching 350.09 g m-2 of CO2 in CT, and 51.7 and 5.5 g m-2 of CO2 in RT and MT respectively. The amount of C lost in the form of CO2 due to soil tillage practices was significant and comparable to the estimated value of potential annual C accumulation resulting from changes in the harvesting system in Brazil from burning of plant residues to the adoption of green cane harvesting. The CO 2 emissions in the CT system could respond to a loss of 80% of the potential soil C accumulated over one year as result of the adoption of mechanized sugarcane harvesting. Meanwhile, soil tillage during the renewal of the sugar plantation using RT and MT methods would result in low impact, with losses of 12% and 2% of the C that could potentially be accumulated during a one year period. © 2013 IOP Publishing Ltd.

Growth and carbon isotopes of Mediterranean trees reveal contrasting responses to increased carbon dioxide and drought

Forest dynamics will depend upon the physiological performance of individual tree species under more stressful conditions caused by climate change. In order to compare the idiosyncratic responses of Mediterranean tree species (Quercus faginea, Pinus nigra, Juniperus thurifera) coexisting in forests of central Spain, we evaluated the temporal changes in secondary growth (basal area increment; BAI) and intrinsic water-use efficiency (iWUE) during the last four decades, determined how coexisting species are responding to increases in atmospheric CO2 concentrations (Ca) and drought stress, and assessed the relationship among iWUE and growth during climatically contrasting years. All species increased their iWUE (ca. +15 to +21 %) between the 1970s and the 2000s. This increase was positively related to Ca for J. thurifera and to higher Ca and drought for Q. faginea and P. nigra. During climatically favourable years the study species either increased or maintained their growth at rising iWUE, suggesting a higher CO2 uptake. However, during unfavourable climatic years Q. faginea and especially P. nigra showed sharp declines in growth at enhanced iWUE, likely caused by a reduced stomatal conductance to save water under stressful dry conditions. In contrast, J. thurifera showed enhanced growth also during unfavourable years at increased iWUE, denoting a beneficial effect of Ca even under climatically harsh conditions. Our results reveal significant inter-specific differences in growth driven by alternative physiological responses to increasing drought stress. Thus, forest composition in the Mediterranean region might be altered due to contrasting capacities of coexisting tree species to withstand increasingly stressful conditions. © 2013 Springer-Verlag Berlin Heidelberg.

Problemas fitossanitários e crescimento de duas cultivares de café durante o primeiro ano em experimento FACE (“Free Air Carbon Dioxide Enrichment”)

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Increased carbon dioxide concentration in the air reduces the severity of Ceratocystis wilt in Eucalyptus clonal plantlets

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A time series sequestration and storage model of atmospheric carbon dioxide

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Increased atmospheric carbon dioxide concentration: effects on eucalypt rust (Puccinia psidii), C:N ratio and essential oils in eucalypt clonal plantlets

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The calcium looping cycle study for capturing carbon dioxide applied to the energy generation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Seasonal fluctuation of soil carbon dioxide emission in differently managed pastures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Supercritical carbonation treatment on extruded fibre-cement reinforced with vegetable fibres

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of elevated atmospheric carbon dioxide on the biological control of coffee leaf rust under controlled conditions

The effect of elevated atmospheric CO2 concentration on biological control of coffee leaf rust, caused by Hemileia vastatrix, was evaluated by leaf disc assay, under controlled conditions. The biocontrol agents Bacillus subtilis, Bacillus pumilus and Lecanicillium longisporum were applied 24h before, 24h after, and simultaneously with the H. vastatrix on leaf discs (diameter of 1.5cm). The CO2 concentrations tested were: 380, 430, 700 and 1300ppm for B. subtilis and B. pumilus; and 380, 430, 670 and 1200ppm for L. longisporum. The antagonists were not affected by CO2 concentrations. B. subtilis was the most effective in controlling the disease when applied before and simultaneously with pathogen.

Seasonal Carbon Dioxide and Oxygen Concentrations in the Dens of Hibernating Mammals (Sciuridae)

This paper reports seasonal changes in respiratory gases in artificial dens of two species of hibernators indigenous to central and northern Alaska: Citellus parryi ablusus(Osgood) and Marmota broweri Hall and Gilmore (Sciuridae).

Supercritical CO2 extraction of phenolic compounds from Baccharis dracunculifolia

Extracts from Baccharis dracunculifolia leaves were obtained using the following solvents: supercritical carbon dioxide (SC-CO2), ethanol and methanol. Supercritical extraction was carried out at temperatures of 40, 50 and 60 degrees C and pressures of 20, 30 and 40 MPa. Four phenolic compounds were analysed in the extracts by high-performance liquid chromatography: 3,5-diprenyl-4-hydroxycinnamic acid (DHCA or artepillin C); 3-prenyl-4-hydroxycinnamic acid (PHCA); 4-hydroxycinnamic acid (p-coumaric acid) and 4-methoxy-3,5,7-trihydroxyflavone (kaempferide). The global extraction yields (X-0) obtained by the conventional methods with ethanol and methanol were higher than those obtained by SC-CO2. However on analysing the components of interest extracted at 60 degrees C and 40 MPa, the extraction yields of kaempferide, DHCA and PHCA were 156%, 98% and 64% higher, respectively, than in the ethanolic extracts. Only the p-coumaric acid extraction yield was better when extracted using the conventional method. (C) 2008 Elsevier B.V. All rights reserved.