Carbon Dioxide Research Papers - Academia.edu (original) (raw)

1] A comparison of radiative transfer models for simulating radiances from the Atmospheric Infrared Sounder (AIRS), has been undertaken. Results from 14 line-by-line and fast parameterized infrared models were submitted. Several aspects of the models were compared. First, the forward model calculations for all 2378 AIRS channels for 52 diverse atmospheric profiles and one tropical Pacific profile coincident with AIRS data were performed for three local zenith viewing angles: nadir, 45, and 60 degrees. Second, for a subset of the models and only 20 AIRS channels the transmittances from each layer to space were provided. Finally, for some models the Jacobians with respect to temperature, water vapor, and ozone were also computed. For the forward model calculations, most models agree to within 0.02 K when compared to a reference lineby-line model averaged over a subset of profiles, with the exception of a few spectral regions. When compared with AIRS observations, however, the mean differences increase to 0.2 K, and for a few models even greater differences are seen. The transmittance differences highlighted regions of the spectrum where the spectroscopy of the models differs, particularly in the carbon dioxide absorption bands at 667 cm À1 and 2386 cm À1 . For the Jacobians all models have some profiles/channels that do not fit the reference well, and the main problems are documented here. The model differences only increase slightly for off-nadir viewing angles for both forward and Jacobian calculations.

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- Remote Sensing, Carbon Dioxide, Data Assimilation, Multidisciplinary

Geological carbon dioxide storage (CCS) has the potential to make a significant contribution to the decarbonisation of the UK. Amid concerns over maintaining security, and hence diversity, of supply, CCS could allow the continued use of coal, oil and gas whilst avoiding the CO 2 emissions currently associated with fossil fuel use. This project has explored some of the geological, environmental, technical, economic and social implications of this technology. The UK is well placed to exploit CCS with a large offshore storage capacity, both in disused oil and gas fields and saline aquifers. This capacity should be sufficient to store CO 2 from the power sector (at current levels) for a least one century, using well understood and therefore likely to be lower-risk, depleted hydrocarbon fields and contained parts of aquifers. It is very difficult to produce reliable estimates of the (potentially much larger) storage capacity of the less well understood geological reservoirs such as non-confined parts of aquifers. With the majority of its large coal fired power stations due to be retired during the next 15 to 20 years, the UK is at a natural decision point with respect to the future of power generation from coal; the existence of both national reserves and the infrastructure for receiving imported coal makes clean coal technology a realistic option. The notion of CCS as a 'bridging' or 'stop-gap' technology (i.e. whilst we develop 'genuinely' sustainable renewable energy technologies) needs to be examined somewhat critically, especially given the scale of global coal reserves. If CCS plant is built, then it is likely that technological innovation will bring down the costs of CO 2 capture, such that it could become increasingly attractive. As with any capitalintensive option, there is a danger of becoming 'locked-in' to a CCS system. The costs of CCS in our model for UK power stations in the East Midlands and Yorkshire to reservoirs in the North Sea are between £25 and £60 per tonne of CO 2 captured, transported and stored. This is between about 2 and 4 times the current traded price of a tonne of CO 2 in the EU Emissions Trading Scheme. In addition to the technical and economic requirements of the CCS technology, it should also be socially and environmentally acceptable. Our research has shown that, given an acceptance of the severity and urgency of addressing climate change, CCS is viewed favourably by members of the public, provided it is adopted within a portfolio of other measures. The most commonly voiced concern from the public is that of leakage and this remains perhaps the greatest uncertainty with CCS. It is not possible to make general statements concerning storage security; assessments must be site specific. The impacts of any potential leakage are also somewhat uncertain but should be balanced against the deleterious effects of increased acidification in the oceans due to uptake of elevated atmospheric CO 2 that have already been observed. Provided adequate long term monitoring can be ensured, any leakage of CO 2 from a storage site is likely to have minimal localised impacts as long as leaks are rapidly repaired. A regulatory framework for CCS will need to include risk assessment of potential environmental and health and safety impacts, accounting and 1 monitoring and liability for the long term. In summary, although there remain uncertainties to be resolved through research and demonstration projects, our assessment demonstrates that CCS holds great potential for significant cuts in CO 2 emissions as we develop long term alternatives to fossil fuel use. CCS can contribute to reducing emissions of CO 2 into the atmosphere in the near term (i.e. peak-shaving the future atmospheric concentration of CO 2 ), with the potential to continue to deliver significant CO 2 reductions over the long term.

- by ray purdy
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- Climate Change, Renewable Energy, Carbon Dioxide, Integrated assessment
- by H. Hooghiemstra
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- Ancient History, Environmental policy, Carbon Dioxide, Climate

Eccrine porocarcinoma is a rare malignant tumor arising from the intraepidermal ductal portion of the eccfine sweat gland (acrosyringium). It usually affects older persons and is located most commonly on the lower extremities. We describe a 55-year-old man with an aggressive metastasizing eccrine porocarcinoma diagnosed 10 years after the primary lesion. The metastatic lesions were located in the pubic area and scrotum and were associated with progressive lymphedema. Several biopsy specimens revealed numerous rumor cells in the dermis and especially in the lumina of lymph and blood vessels. Immunohistochemical studies showed staining with cytokeratin KL1, epithelial membrane antigen, Ca 15-3, and Ca 19-9. Vimenfin, S-100 protein, neuron specific enolase, and carcino-embryonlc antigen were negative. Treatment with carbon dioxide laser failed. The use of interferon alfa-2a for 9 months stopped progression of the rumor. (J Am Acad Dermatol 1996;35:860-4.) Primary adenocarcinomas arising from the eccrine sweat glands are rare and represent approximately 0.005% of epithelial cutaneous neoplasms.

- by Bernard Guillot and +1
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- Carbon Dioxide, Clinical Sciences, Lower Extremity, Blood Vessel

The impact of high O 2 + high CO 2 modified atmospheres (MA), on the preservation of minimally processed carrots was studied. A combination of 50% O 2 + 30% CO 2 prolonged the shelf life of sliced carrots compared to storage in air by 2 to 3 d. When the carrots received a pre-treatment with a 0.1% citric acid dip and a sodium alginate edible coating prior to packaging, shelf life was extended by 5 to 7 d. Advantages and disadvantages of the proposed MA over previously recommended MA (1% O 2 + 10% CO 2 ), related to a range of physicochemical and microbiological characteristics of carrots are discussed.

- by Leon Gorris and +1
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- Chemical Engineering, Food Science, Carbon Dioxide, Food

The kinetics of abiotic oxidation in the dark and the kinetics of biological mineralization in soil and in a compost environment of thermally oxidized LDPE were studied. It was demonstrated that different activation energies are obtained for the thermal oxidation, depending on the composition of the materials. Significantly higher levels of biodegradability have been obtained in a soil environment at 23 C compared with the compost environment at 58 C. After two years of mineralization, 91% conversion to carbon dioxide was obtained in the soil test, compared with 43% in the compost test. The differences between fungal, archaeal and bacterial community structures in soil and compost after 607 days of biodegradability assay were mapped out. It was found that the most dominant bacterial and fungal terminal restriction fragments (TRFs) in the compost containing the test material are significantly different from the TRFs in the other environments.

- by Nazdaneh Yarahmadi
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- Materials Engineering, Chemical Engineering, Carbon Dioxide, Kinetics

We measured nitrous oxide (N 2 O), dinitrogen (N 2 ), methane (CH 4 ), and carbon dioxide (CO 2 ) fluxes in horizontal and vertical flow constructed wetlands (CW) and in a riparian alder stand in southern Estonia using the closed chamber method in the period from October 2001 to November 2003. The replicates' average values of N 2 O, N 2 , CH 4 and CO 2 fluxes from the riparian gray alder stand varied from −0.4 to 58 g N 2 O-N m −2 h −1 , 0.02-17.4 mg N 2 -N m −2 h −1 , 0.1-265 g CH 4 -C m −2 h −1 and 55-61 mg CO 2 -C m −2 h −1 , respectively. In horizontal subsurface flow (HSSF) beds of CWs, the average N 2 emission varied from 0.17 to 130 and from 0.33 to 119 mg N 2 -N m −2 h −1 in the vertical subsurface flow (VSSF) beds. The average N 2 O-N emission from the microsites above the inflow pipes of the HSSF CWs was 6.4-31 g N 2 O-N m −2 h −1 , whereas the outflow microsites emitted 2.4-8 g N 2 O-N m −2 h −1 . In VSSF beds, the same value was 35.6-44.7 g N 2 O-N m −2 h −1 . The average CH 4 emission from the inflow and outflow microsites in the HSSF CWs differed significantly, ranging from 640 to 9715 and from 30 to 770 g CH 4 -C m −2 h −1 , respectively. The average CO 2 emission was somewhat higher in VSSF beds (140-291 mg CO 2 -C m −2 h −1 ) and at the inflow microsites of HSSF beds (61-140 mg CO 2 -C m −2 h −1 ). The global warming potential (GWP) from N 2 O and CH 4 was comparatively high in both types of CWs (4.8 ± 9.8 and 6.8 ± 16.2 t CO 2 eq ha −1 a −1 in the HSSF CW 6.5 ± 13.0 and 5.3 ± 24.7 t CO 2 eq ha −1 a −1 in the hybrid CW, respectively). The GWP of the riparian alder forest from both N 2 O and CH 4 was relatively low (0.4 ± 1.0 and 0.1 ± 0.30 t CO 2 eq ha −1 a −1 , respectively), whereas the CO 2 -C flux was remarkable (3.5 ± 3.7 t ha −1 a −1 ). The global influence of CWs is not significant. Even if all global domestic wastewater were treated by wetlands, their share of the trace gas emission budget would be less than 1%.

- by Ülo Mander
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- Engineering, Ecological Engineering, Earth Sciences, Carbon Dioxide

Microperforated films (perforation diameter <200 lm) are an option for achieving the appropriate gaseous composition in modified atmosphere packaging, especially for fresh-cut products. In this project, static techniques were used to experimentally measure the oxygen and carbon dioxide transmission rates of microperforated films. Twenty nine microperforations of different dimensions (from 40 Â 30 lm to 350 Â 110 lm) and thickness (from 29 to 57 lm) were tested in the project. A potential equation was found to provide a good prediction of the dependence of the O 2 and CO 2 transmission rates on the perforation area. The data predicted by the equation was compared with those from five other bibliographic models. The empirical equation agrees, within the experimental range, with the modified Fick's law (considering the total diffusive pass length of a perforation as the sum of the perforation length and end correction term). The predictions of the proposed equation for thicker films and holes of larger dimensions (equivalent radius >3000 lm) correspond to those of the empirical models.

- by Jaime Eduardo Gonzalez-Díaz
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- Food Engineering, Carbon Dioxide, Packaging, Film

A special nanobubble generation system has been developed for evaluating the effect of nanobubble on froth flotation. In this study, an eight-factor five-level Central Composite Experimental Design was conducted for investigating eight important parameters governing the median size and the volume of nanobubbles. These process parameters included surfactant concentration, dissolved oxygen (O 2 ) content, dissolved carbon dioxide gas (CO 2 ) content, pressure drop in cavitation tube nozzle, <50 nm hydrophobic particle concentration, <50 nm hydrophilic particle concentration, slurry temperature and the time interval after nanobubble generation. The properties, stability and uniformity of nanobubbles were investigated. The study of the produced nanobubble's effects on the characteristics of microbubble solutions and millimeter scale bubble solutions was performed in a 50.8 mm column.

- by Rick Honaker and +2
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- Engineering, Carbon Dioxide, Experimental Design, Pressure Drop

While research and development of algal biofuels are currently receiving much interest and funding, they are still not commercially viable at today's fossil fuel prices. However, a niche opportunity may exist where algae are grown as a by-product of high rate algal ponds (HRAPs) operated for wastewater treatment. In addition to significantly better economics, algal biofuel production from wastewater treatment HRAPs has a much smaller environmental footprint compared to commercial algal production HRAPs which consume freshwater and fertilisers. In this paper the critical parameters that limit algal cultivation, production and harvest are reviewed and practical options that may enhance the net harvestable algal production from wastewater treatment HRAPs including CO 2 addition, species control, control of grazers and parasites and bioflocculation are discussed.

- by Andy Shilton
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- Carbon Dioxide, Biomass, Water Purification, Wastewater Treatment

Carbon capture and storage (CCS) is vital to reduce CO 2 emissions to the atmosphere, potentially providing 20% of the needed reductions in global emissions. Research and demonstration projects are important to increase scientific understanding of CCS, and making processes and results widely available helps to reduce public concerns, which may otherwise block this technology. The Otway Project has provided verification of the underlying science of CO 2 storage in a depleted gas field, and shows that the support of all stakeholders can be earned and retained. Quantitative verification of long-term storage has been demonstrated. A direct measurement of storage efficiency has been made, confirming that CO 2 storage in depleted gas fields can be safe and effective, and that these structures could store globally significant amounts of CO 2 . carbon storage | geosequestration | carbon dioxide | climate change | energy policy

- by Jim Underschultz and +2
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- Climate Change, Carbon Dioxide, Carbon Sequestration, Air pollution

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- by Joe Kerry
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- Carbon Dioxide, Nitrogen, Modified atmosphere packaging, Meat products
- by kirsi lehto
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- Microbiology, Carbon Dioxide, Photosynthesis, Medical Microbiology

Net primary production (NPP), the difference between CO 2 fixed by photosynthesis and CO 2 lost to autotrophic respiration, is one of the most important components of the carbon cycle. Our goal was to develop a simple regression model to estimate global NPP using climate and land cover data. Approximately 5600 global data points with observed mean annual NPP, land cover class, precipitation, and temperature were compiled. Precipitation was better correlated with NPP than temperature, and it explained much more of the variability in mean annual NPP for grass-or shrub-dominated systems (r 2 ¼ 0.68) than for tree-dominated systems (r 2 ¼ 0.39). For a given precipitation level, treedominated systems had significantly higher NPP (;100-150 g CÁm À2 Áyr À1 ) than non-treedominated systems. Consequently, previous empirical models developed to predict NPP based on precipitation and temperature (e.g., the Miami model) tended to overestimate NPP for non-tree-dominated systems. Our new model developed at the National Center for Ecological Analysis and Synthesis (the NCEAS model) predicts NPP for tree-dominated systems based on precipitation and temperature; but for non-tree-dominated systems NPP is solely a function of precipitation because including a temperature function increased model error for these systems. Lower NPP in non-tree-dominated systems is likely related to decreased water and nutrient use efficiency and higher nutrient loss rates from more frequent fire disturbances. Late 20th century aboveground and total NPP for global potential native vegetation using the NCEAS model are estimated to be ;28 Pg and ;46 Pg C/yr, respectively. The NCEAS model estimated an ;13% increase in global total NPP for potential vegetation from 1901 to 2000 based on changing precipitation and temperature patterns.

- by Vanessa Ramirez
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- Environmental Science, Carbon Dioxide, Photosynthesis, Biomass

Among prokaryotes, the large vacuolated marine sulphur bacteria are unique in their ability to store, transport and metabolize significant quantities of sulphur, nitrogen, phosphorus and carbon compounds. In this study, unresolved questions of metabolism, storage management and behaviour were addressed in laboratory experiments with Thioploca species collected on the continental shelf off Chile. The Thioploca cells had an aerobic metabolism with a potential oxygen uptake rate of 1760 lmol O 2 per dm 3 biovolume per h, equivalent to 4.4 nmol O 2 per min per mg protein. When high ambient sulphide concentrations (B200 lM) were present, a sulphide uptake of 6220 ± 2230 lmol H 2 S per dm 3 per h, (mean ± s.e.m., n ¼ 4) was measured. This sulphide uptake rate was six times higher than the oxidation rate of elemental sulphur by oxygen or nitrate, thus indicating a rapid sulphur accumulation by Thioploca. Thioploca reduce nitrate to ammonium and we found that dinitrogen was not produced, neither through denitrification nor through anammox activity. Unexpectedly, polyphosphate storage was not detectable by microautoradiography in physiological assays or by staining and microscopy. Carbon dioxide fixation increased when nitrate and nitrite were externally available and when organic carbon was added to incubations. Sulphide addition did not increase carbon dioxide fixation, indicating that Thioploca use excess of sulphide to rapidly accumulate sulphur rather than to accelerate growth. This is interpreted as an adaptation to infrequent high sulphate reduction rates in the seabed. The physiology and behaviour of Thioploca are summarized and the adaptations to an environment, dominated by infrequent oxygen availability and periods of high sulphide abundance, are discussed.

- by N. Revsbech
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- Carbon Dioxide, Biology, Chile, Biological Sciences

Photon flux density (PFD) and water availability, the daily and seasonal factors that vary most in tropical environments, were examined to see how they influenced expression of crassulacean acid metabolism (CAM) in 3year-old Clusia shrubs native to Panama. Instead of the commonly used single-leaf approach, diel CO 2 exchange was measured for whole individual canopies of plants in large soil containers inside a naturally illuminated 8.8 m 3 chamber. In well-watered C. rosea, a mainly constitutive CAM species, nocturnally fixed CO 2 contributed about 50% to 24 h carbon gain on sunny days but the contribution decreased to zero following overcast days. Nonetheless, CO 2 fixation in the light responded in such a way that 24 h carbon gain was largely conserved across the range of daily PFDs. The response of C. rosea to drought was similarly buffered. A facultative component of CAM expression led to reversible increases in nocturnal carbon gain that offset drought-induced reductions of CO 2 fixation in the light. Clusia cylindrica was a C 3 plant when well-watered but exhibited CAM when subjected to water stress. The induction of CAM was fully reversible upon rewatering. C. cylindrica joins C. pratensis as the most unambiguous facultative CAM species reported in the genus Clusia.

- by Milton N. Garcia J.
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- Botany, Carbon Dioxide, Photosynthesis, Plant Biology
- by Pertti Martikainen
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- Carbon Dioxide, Biology, Filtration, Public Health
- by Cletos Mapiye
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- Mathematics, Nutrition and Dietetics, Carbon Dioxide, Energy Metabolism

The South American lungfish, Lepidosiren paradoxa inhabits seasonal environments in the Central Amazon and Paraná-Paraguay basins that undergo significant oscillations in temperature throughout the year. They rely on different gas exchange organs, such as gills and skin for aquatic gas exchange while their truly bilateral lungs are responsible for aerial gas exchange; however, there are no data available on the individual contributions of the skin and the gills to total aquatic gas exchange in L. paradoxa. Thus, in the present study we quantify the relative contributions of skin and gills on total aquatic gas exchange during warm (35°C) and cold exposure (20°C) in addition to the effects of aerial and aquatic hypercarbia on aquatic gas exchange and gill ventilation rate (fG; 25°C), respectively. Elevated temperature (35°C) caused a significant increase in the contribution of cutaneous (from 0.61±0.13 to 1.34±0.26ml. STPD.h(-1)kg(-1)) and branchial (from 0.54±0.17 to 1.73±0.53ml. STP...

- by Kênia Bícego
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- Carbon Dioxide, Biological Sciences, Fishes, Skin

The performance of a hollow fibre artificial lung ('Capiox E') was analysed by measurement of the 'parallel deadspace' of the device under varying conditions in 21 patients. The efficiency with which carbon dioxide was exchanged was determined by the time available for equilibration between the blood and gas phases. When this equilibration coefficient was less than 12 seconds per litre of blood flow per litre of gas flow, there was a marked reduction in the efficiency of gas exchange. Under certain conditions, the 'counter-current' design of the device apparently permitted the clearance of carbon dioxide at a partial pressure greater than that which was found in the mixed venous blood. This anomalous behaviour may represent in vivo confirmation of the Haldane effect.

- by David Pybus
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- Carbon Dioxide, Rheology, Efficiency, Body Temperature

Use of cuffed oropharyngeal vs laryngeal mask airway in elderly patients Purpose: This study was designed to compare the new cuffed oropharyngeal airway (COPA) to the laryngeal mask airway (LMA) in elderly patients. Methods: In a randomized, controlled study, 80 patients, age ~ 65, ASA I-III, undergoing urology procedures, were managed with either COPA or LMA. Propofol requirements for insertion of the devices, ease of insertion and removal, airway manipulations, mean arterial pressure, heart rate, PETCO 2, SpO 2, peak inspiratory pressure, selection of the appropriate size of the device and leaks, fibreoptic visualization of larynx and complications were studied. l~,stdts: There were more airway manipulations in the COPA group than in the LMA group (40% and 5% respectively) whereas PETCO 2 was higher in the LiVlA group (P <0.05). In 60% of COPA patients the vocal cords could not be visualized but ventilation was adequate in all but two cases. Postoperative sore throat occurred in 20~ of patients with LMA vs 10% with COPA). Bloody secretions on the device were present in two patients managed with LMA. Conclusion: In elderly patients COPA required more airway manipulations than the LMA. Laryngeal mask airway caused more sore throats, but was better for flbreoptic visualisation of the larynx. Both are excellent options when intubation is not indicated/desired. Objectif: La pr6sente &ude a &E men& pour comparer deux appareils utilis& chez des patients ~g~s : la canule oropharyng~e & ballonnet (COPB) et le masque laryng6 (ML). M&hode : Dans une &ude randemis& et contr61~e, on a ins&~ une COPB ou un M L chez 80 patients, ~.g& de 65 ans, ASA I-III, devant subir une intervention urologique. Le propofol n&essaire pendant I'insertion du dispositif, la facilit~ de rinsertion et du retrait, les manipulations requises, la tension art6rielle moyenne, la fr~quence cardiaque, la PETCO2, la SpO 2, la pression inspiratoire de or&e, l'appareil choisi selon la faille approprLae et les fuites, la visualisation fibroscopique du larynx et les complications ont ~t~ 6tudi~s. l~,sultats : l'insertion de la COPB a demand6 plus de manipulations que celle du ML (40 0% et 5 %, respectivement) tandis que la PETCO 2 &ait plus haute avec le ML (P < 0,05). Chez 60 % des patients qui ont regu la COPB, on ne pouvait visualiser les cordes vocales, mais la ventilation 6tait ad6quate chez tous sauf chez deux patients. Des maux de gorge postop&atoires sont survenus chez 20 % des patients avec le ML vs I0 0% avec la COPB). Des s&r~tions sanguinolentes 6taient pr6sentes sur l'appareil de deux patients portant le ML. Conclusion : Chez les patients ~g&, l'insertion de la COPB demande plus de manipulations que celle du ML. Le ML cause davantage de maux de gorge, mais permet une meilleure visualisation fibroscopique du larynx. Les deux dispositifs test6s sont trEs utiles lorsque rintubation n'est pas indiqu6e ou souhait6e.

- by Daniel Geva
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- Carbon Dioxide, Stents, Canadian, Blood Pressure
- by Mark Zahniser and +1
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- Mechanical Engineering, Carbon Dioxide, Optical physics, Room Temperature
- by Edward Anthony and +1
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- Carbon Dioxide, Multidisciplinary, Environmental science and technology, Power Plants

This study examined the role of pregnancy-induced changes in wakefulness (or nonchemoreflex) and central chemoreflex drives to breathe, acid-base balance and female sex hormones in the hyperventilation of human pregnancy. Thirty-five healthy women were studied in the third trimester (TM 3 ; 36.3 ± 1.0 wks gestation; mean ± SD) and again 20.2 ± 7.8 wks postpartum (PP). An iso-oxic hyperoxic rebreathing procedure was used to evaluate wakefulness and central chemoreflex drives to breathe. At rest, arterialized venous blood was obtained for the estimation of arterial PCO 2 (PaCO 2 ) and [H + ]. Blood for the determination of plasma strong ion difference ([SID]), albumin ([Alb]), as well as serum progesterone ([P 4 ]) and 17-estradiol ([E 2 ]) concentrations was also obtained at rest. Wakefulness and central chemoreflex drives to breathe, [P 4 ] and [E 2 ], ventilation and V · CO 2 increased, whereas PaCO 2 and the central chemoreflex ventilatory recruitment threshold for PCO 2 (VRTCO 2 ) decreased from PP to TM 3 (all p<0.01). The reductions in PaCO 2 were not related to the increases in [P 4 ] and [E 2 ]. The alkalinizing effects of reductions in PaCO 2 and [Alb] were partly offset by the acidifying effects of a reduced [SID], such that arterial [H + ] was still reduced in TM 3 vs. PP (all p<0.001). A mathematical model of ventilatory control demonstrated that pregnancy-induced changes in wakefulness and central chemoreflex drives to breathe, acid-base balance, V · CO 2 and cerebral blood flow account for the reductions in PaCO 2 , [H + ] and VRTCO 2 . This is the first study to demonstrate that the hyperventilation and attendant hypocapnia/alkalosis of human pregnancy results from a complex interaction of pregnancy-induced changes in wakefulness and central chemoreflex drives to breathe, acid-base balance, metabolic rate and cerebral blood flow.

- by James Duffin
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- Carbon Dioxide, Modeling, Sex Hormones, Mathematical Modeling

FLUORESCENT QUANTUM EFFICIENCY danger of disrupting the molecule. The high degree of resonance (in chemical terminology) that exists in the structure being considered would certainly provide for rapid distribution of the excess photon energy throughout the molecule. The nature of the emission site and its location in the molecule are still uncertain.

- by William Malkmus
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- Carbon Dioxide, Infrared

We investigated whether spiders fed lipid-rich rather than protein-rich prey elevate metabolism to avoid carrying excessive lipid deposits, or whether they store ingested lipids as a buffer against possible future starvation. We fed wolf spiders (Pardosa prativaga) prey of different lipid:protein compositions and measured the metabolic rate of spiders using closed respirometry during feeding and fasting. After a 16-day feeding period, spider lipid:protein composition was significantly affected by the lipid:protein composition of their prey. Feeding caused a large and fast increase in metabolism. The cost of feeding and digestion was estimated to average 21% of the ingested energy irrespective of diet. We found no
difference in basal metabolic rate between dietary treatments. During starvation ˙VO2 and ˙VCO2 decreased gradually, and the larger lipid stores in spiders fed lipid-rich prey appeared to extend survival of these spiders under starvation compared to spiders fed protein-rich prey. The results show that these spiders do not adjust metabolism in order to maintain a constant body composition when prey nutrient composition varies. Instead, lipids are stored efficiently and help to prepare the spiders for the long periods of food deprivation that may occur as a consequence of their opportunistic feeding strategy.

- by Kim Jensen
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- Physiology, Zoology, Carbon Dioxide, Insect Physiology

Due to more stringent requirements to protect personnel against hazardous gasses, the inspiratory resistance of the present generation of respiratory protective devices tends to increase. Therefore an important question is to what extent inspiratory resistance may increase without giving problems during physical work. In this study the effects of three levels (0.24; 1.4 and 8.3 kPa s l À1 ) of inspiratory resistance were tested on maximal voluntary performance. Nine male subjects performed a graded exercise test on a cycle ergometer with and without these three levels of inspiratory resistance. Oxygen consumption, heart rate, time to exhaustion and external work were measured. The results of these experiments showed that increasing inspiratory resistance led to a reduction of time to exhaustion (TTE) on a graded exercise test(GXT). Without inspiratory resistance the mean TTE was 11.9 min, the three levels of resistance gave the following mean TTE's: 10.7, 7.8 and 2.7 min. This study showed that TTE on a GXT can be predicted when physical fitness (VO 2 -max) of the subject and inspiratory resistance are known. The metabolic rate of the subjects was higher with inspiratory resistance, but no differences were found between the three selected inspiratory loads. Other breathing parameters as minute ventilation, tidal volume, expiration time and breathing frequency showed no or minor differences between the inspiratory resistances. The most important conclusion of these experiments is that the overall workload increases due to an increase in inspiratory resistance by wearing respiratory protective devices. r

- by Ronald Heus and +1
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- Carbon Dioxide, Adolescent, Applied Ergonomics, Heart rate

BACKGROUND: In this study, we analyzed the effect of the alveolar recruitment strategy (ARS) and positive end-expiratory pressure (PEEP) titration on Phase III slope (S III ) of volumetric capnography (VC) in morbidly obese patients. METHODS: Eleven anesthetized morbidly obese patients were studied. Lungs were ventilated with tidal volumes of 10 mL ⅐ kg Ϫ1 , respiratory rates of 12-14 bpm, inspiration:expiration ratio of 1:2, and Fio 2 of 0.4. ARS was performed by increasing PEEP in steps of five from 0 end-expiratory pressure to 15 cm H 2 O. During lung recruitment, plateau pressure was limited to 50 cm H 2 O, whereas tidal volume was increased to the ventilator's maximum value of 1400 mL, and PEEP was increased to 20 cm H 2 O for 2 min. Thereafter, PEEP was reduced in steps of 5 cm H 2 O, from 15 to 0. VC, arterial blood gases, and lung mechanics data were determined for each PEEP step. RESULTS: S III decreased from 0.014 Ϯ 0.006 to 0.005 Ϯ 0.005 mm Hg/mL when 0 end-expiratory pressure was compared against 15 cm H 2 O of PEEP after ARS (15 ARS , P Ͻ 0.05). This decrement in S III was accompanied by increases in Pao 2 (27%, P Ͻ 0.002) and compliance (32%, P Ͻ 0.001), whereas Paco 2 decreased by 8% (P Ͻ 0.038) when comparing values before and after ARS. A good prediction of the lung recruitment effect by S III was derived from the receiver operating characteristic curve analysis (area under the curve of 0.81, sensitivity of 0.75, and specificity of 0.74; P Ͻ 0.001). CONCLUSION: The S III in VC was useful to detect the optimal level of PEEP after lung recruitment in anesthetized morbidly obese patients.

- by Isabel Passoni and +1
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- Carbon Dioxide, Anesthesia, Lung, Clinical Sciences

In this study, 27 CDC traps were modified with various attractive features and compared with a CDC trap with no light source or baits to evaluate the effects on attraction to Phlebotomus papatasi (Scopoli) north of the Dead Sea near Jericho. Attractive features included CO2, lights, colored trap bodies, heat, moisture, chemical lures and different combinations of the same. Traps were placed 20m apart and rotated from one trap location to the next after 24h trapping periods. The most significant attractive feature was CO2, which attracted more sand flies than any other feature evaluated. Ultraviolet light was the next most attractive feature, followed by incandescent light. When evaluated alone, black or white trap bodies, heat and moisture, all influenced trap catch but effects were greater when these attractive features were used together. The results of this study suggest that traps with CO2 and UV light could be used in batteries as control interventions if suitable CO2 sources b...

- by Rui-de Xue
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- Animal Behavior, Carbon Dioxide, Biological Sciences, Psychodidae

Despite the great interest concerning the relationship between species diversity and ecosystem functioning, there is virtually no knowledge as to how the diversity of decomposer microbes influences the decomposition rate of soil organic matter. We established a microcosm study in which the number of soil fungi was investigated in relation to the system's ability to (i) degrade raw coniferous forest humus, and (ii) use resources that were either added to the systems or released into the soils after a disturbance (drought). With the exception of the most diverse treatment, in each of the six replicates of each of the six diversity treatments (1, 3, 6, 12, 24 or 43 taxa), fungal taxa were randomly chosen from a pool of 43 commonly isolated fungal species of raw humus. Two months after initiation of the study CO 2 production increased as fungal diversity increased, but in the species-poor end of the diversity gradient only. Addition of various energy resources to the microcosms generally increased the level of soil respiration but did not affect the shape of the diversity-CO 2 -production curve. Rewetting the soil after severe drought resulted in a rapid flush of CO 2 , particularly in the most diverse communities. The biomass of the fungi in the non-disturbed soils, and soil NH 4 -N concentration and soil pH in both disturbed and non-disturbed systems were slightly but significantly higher in the diverse than in the simple systems. Fungal species richness had no influence on the organic matter content of the humus at the end of the experiment. The results suggest that the functional efficiency of fungal communities can increase with the number of fungal taxa. This diversity effect was, however, significant at the species-poor end of the diversity gradient only, which implies considerable functional equivalency (redundancy) among the decomposer fungi.

- by Heikki Setälä
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- Carbon Dioxide, Treatment, Ecology, Population Dynamics

The objective of the study has been to investigate whether cold-adapted microorganisms (CAMs) are metabolising hydrocarbons in situ at sub-zero temperatures. Since the summer 2001, soil temperatures and soil gas concentrations of oxygen (O 2 ) and carbon dioxide (CO 2 ) at various depths at a petroleum hydrocarbon contaminated permafrost site at Longyearbyen, Spitsbergen, have continuously been measured and compared to data from a nearby non-contaminated site. We have previously reported on unchanged microbial O 2 consumption in the active layer for about 12 days after the soil temperatures decreased below 0 8C in late October 2001 and we are now reporting on the microbial activity in the soil profile from January to September 2002. The empirical data have been compared to theoretical simulations of O 2 concentration as a function of soil depth and time from when the CAMs became active in spring until steady-state conditions were achieved in the summer. At the 0.7 m depth in the oil-plume site, microbial O 2 consumption started in the middle of April, about 45 days before the soil thawed. There was no coincidence between the microbial activation time and the thawing time of the soil. The CAMs became active at temperatures of about À6 8C, but the main degradation activity occurred at temperatures between À1 and À3 8C. When the soil thawed, the hydrocarbon degradation was probably limited by the O 2 supply. In the summer months where we expected the greatest degradation activity to occur because of positive temperatures and access to water, the degradation was limited by O 2 depletion. The overall data from this arctic permafrost site indicate that without other limiting conditions such as O 2 and 0165-232X/$ -see front matter D substrate availability, the active biodegradation period can be extended to about 6 months despite periods with sub-zero soil temperatures. D

- by Cam Gunn
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- Civil Engineering, Carbon Dioxide, Permafrost, Steady state

Crystalline Cd(OH) 2 /CdCO 3 nanowires, having lengths in the range from 0.3 up to several microns and 5-30 nm in diameter, were synthesized by a microwave-assisted wet chemical route and used as a precursor to obtain CdO nanostructures after a suitable thermal treatment in air. The morphology and microstructure of the as-synthesized and annealed materials have been investigated by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and thermogravimetry-differential scanning calorimetry. The change in morphology and electrical properties with temperature has revealed a wire-to-rod transformation along with a decreases of electrical resistance.

- by A. Stassi and +1
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- Carbon Dioxide, Scanning Electron Microscopy, Transmission Electron Microscopy, Nanotechnology

Atlantic salmon (Salmo salar L.) smolts (mean weight 66 g) in freshwater were exposed to three replicate levels of carbon dioxide (CO 2 ) partial pressures for 60 days in an open flow system: 2 mm Hg (6 mg l À 1 ; control), 5 mm Hg (16 mg l À 1 ; medium) and 7 mm Hg (24 mg l À 1 ; high) at constant pH. Water temperature was 7 -9 jC and oxygen concentration higher than 9 mg l À 1 . All groups were transferred to 34x seawater on day 60 and kept there for 150 days. No significant differences in weight and length were found between groups during the freshwater and seawater period. While mean cellular haemoglobin (in the high group) and plasma chloride (in the medium and high group) were significantly lower than that of the control group during the freshwater period, no significant differences between groups were observed in mean haemoglobin concentration, haematocrit, or gill Na + ,-K + -ATPase activity. Increased nephrocalcinosis and contents of Ca in the kidney in response to increasing water CO 2 levels were observed at day 58. After 4 weeks in seawater, pH in muscle and whole body ash, Ca, P and Zn content were all significantly higher in 0044-8486/03/$ -see front matter D Aquaculture 215 (2003) 301 -319 fish exposed to elevated CO 2 levels during the freshwater period. This indicates that freshwater CO 2 levels affected tissue mineral content after transfer to seawater. D

- by Sveinung Fivelstad
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- Zoology, Carbon Dioxide, Aquaculture, Atlantic Salmon
- by Sébastien Barot
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- Pharmacology, Biochemistry, Bioinformatics, Evolutionary Biology
- by Viacheslav Adamchuk
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- Analytical Chemistry, Carbon Dioxide, Sensors, Soil Microbiology

One limitation of the coronavirus disease 2019 (COVID-19) pandemic response has been the lack of widely available, practical tools to measure factors, such as ventilation and airflow, that can impact transmission risk. The Centers for Disease Control and Prevention (CDC) has recommended that steps be taken to improve ventilation in healthcare facilities, schools, businesses, and households. 1 However, limited guidance has been provided on how to evaluate the adequacy of ventilation. To be useful in real-world settings, tools to assess ventilation must be inexpensive, safe, and easy to use. An ideal tool would provide rapid and easy-to-interpret results that could be used to identify areas with inadequate ventilation and to assess the impact of interventions. One promising candidate as a practical tool to assess ventilation is carbon dioxide monitoring using inexpensive handheld devices that measure carbon dioxide concentrations. The concentration of carbon dioxide in outdoor air is ∼400 parts per million (ppm) versus ∼40,000 ppm in exhaled breath. 2 Thus, carbon dioxide levels rise in occupied spaces that are inadequately ventilated. 2 According to the CDC, carbon dioxide readings >800 ppm in buildings are an indicator of suboptimal ventilation requiring intervention. 1 Carbon dioxide monitoring has been used to assess ventilation and to identify measures to reduce risk in settings such as schools, university buildings, dental offices, motor vehicles, and hospitals. 3-7 The most important limitation of carbon dioxide monitoring is that it does not account for filtering of air. For example, carbon dioxide levels rise above 800 ppm in the cabin of airplanes both in flight and during boarding and deplaning, but the risk for viral transmission may remain low because the air conditioning system provides rapid recirculation of air through high-efficiency particulate air (HEPA) filters. 5 Other potential tools to assess ventilation include handheld particle counters and devices that measure total volatile organic compounds. 8,9 In an assessment of ventilation in public spaces,

- by Curtis Donskey
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- Carbon Dioxide, Ventilation, Airflow, SARS-CoV-2

The leaf economics spectrum (LES) represents a suite of intercorrelated leaf traits concerning construction costs per unit leaf area, nutrient concentrations, and rates of carbon fixation and tissue turnover. Although broad trade-offs among leaf structural and physiological traits have been demonstrated, we still do not have a comprehensive view of the fundamental constraints underlying the LES trade-offs. Here, we investigated physiological and structural mechanisms underpinning the LES by analysing a novel data compilation incorporating rarely considered traits such as the dry mass fraction in cell walls, nitrogen allocation, mesophyll CO2 diffusion and associated anatomical traits for hundreds of species covering major growth forms. The analysis demonstrates that cell wall constituents are major components of leaf dry mass (18-70%), especially in leaves with high leaf mass per unit area (LMA) and long lifespan. A greater fraction of leaf mass in cell walls is typically associated...

- by Tiina Tosens
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- Carbon Dioxide, Biological Sciences, Diffusion, Nitrogen

Carbon dioxide, energy flux measurements and methane chamber measurements were carried out in an arctic wet tussock grassland located on a flood plane of the Kolyma river in NE Siberia over a summer period of 155 days in 2002 and early 2003. Respiration was also measured in April 2004. The study region is characterized by late thaw of the top soil (mid of June) and periodic spring floods. A stagnant water table below the grass canopy is fed by thawing of the active layer of permafrost and by flood water. The climate is continental with average daily temperature in the warmest months of 13 1C (maximum temperature at midday: 28 1C by the end of July), dry air (maximum vapour pressure deficit at midday: 28 hPa) and low rainfall of 50 mm during summer (July-September). Summer evaporation (July-September: 103 mm) exceeded rainfall by a factor of 2. The daily average Bowen ratio (H/LE) was 0.62 during the growing season. Net ecosystem CO 2 uptake reached 10 lmol m À2 s À1 and was related to photon flux density (PFD) and vapour pressure deficit (VPD). The cumulative annual net carbon flux from the atmosphere to the terrestrial surface was estimated to be about À38 g C m À2 yr À1 (negative flux depicts net carbon sink). Winter respiration was extrapolated using the Lloyd and Taylor function. The net carbon balance is composed of a high rate of assimilation in a short summer and a fairly large but uncertain respiration mainly during autumn and spring. Methane flux (about 12 g C m À2 measured over 60 days) was 25% of C uptake during the same period of time (end of July to end of September). Assuming that CH 4 was emitted only in summer, and taking the greenhouse gas warming potential of CH 4 vs. CO 2 into account (factor 23), the study site was a greenhouse gas source (at least 200 g C equivalent m À2 yr À1). Comparing different studies in wetlands and tundra ecosystems as related to latitude, we expect that global warming would rather increase than decrease the CO 2-C sink.

- by onesmus kole
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- Environmental Science, Carbon Dioxide, Global Change Biology, Biological Sciences

Selective Laser Sintering (SLS) produces three-dimensional objects directly from a computer-aided design (CAD) solid model, without part-specific tooling, by repeatedly depositing thin layers of fusible powder and selectively sintering... more

- by Joel Barlow
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- Engineering, Materials Science, Carbon Dioxide, Computer Aided Design

A thermodynamic equilibrium analysis on the multi-reaction system for carbon dioxide reforming of methane in view of carbon formation was performed with Aspen plus based on direct minimization of Gibbs free energy method. The effects of CO 2 /CH 4 ratio (0.5–3), reaction temperature (573–1473 K) and pressure (1–25 atm) on equilibrium conversions, product compositions and solid carbon were studied. Numerical analysis revealed that the optimal working conditions for syngas production in Fischer–Tropsch synthesis were at temperatures higher than 1173 K for CO 2 /CH 4 ratio being 1 at which about 4 mol of syngas (H 2 /CO = 1) could be produced from 2 mol of reactants with negligible amount of carbon formation. Although temperatures above 973 K had suppressed the carbon formation, the moles of water formed increased especially at higher CO 2 /CH 4 ratios (being 2 and 3). The increment could be attributed to RWGS reaction attested by the enhanced number of CO moles, declined H 2 moles and...

- by mohammad jafarbegloo
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- Chemical Engineering, Thermodynamics, Carbon Dioxide, Numerical Analysis

Like our previous work with imidazolium-and phosphonium-based ionic liquids, we report diffusivities over a range of viscosities (71-532 cP) and develop a predictive diffusivity correlation. Reported are the permeability, solubility, and diffusivity data for nine gases in nine ammonium RTILs liquids at 30 • C, as determined with a lag-time technique. The gas solubilities and diffusivities of the ammonium RTILs are of the same magnitude as those for the phosphonium and imidazolium RTILs. The ammonium RTILs used, in this study, included cations with both N-alkyl groups and branched alkyl groups. We also report on ammonium-based RTILs derived from quaternary ammonium surfactants. These surfactantsderived ammonium-based RTILs offer a relatively inexpensive alternative to imidazolium-based RTILs. We compare and contrast the thermodynamic (solubility) and transport (diffusivities) phenomena in the ammonium-based RTILs with both the imidazolium and the phosphonium RTILs in the context of being working fluids in a chemical process. From this comparison came certain "universal" trends for diffusivity in RTILs. Specifically, diffusivity scales roughly with the inverse of the square-root of viscosity and inversely with solute molar volume to the power of 1-1.3. This means that diffusivity, in RTILs, is less dependent on viscosity, and more dependent on solute size than predicted by the conventional Stokes-Einstein model. The gases tested were carbon dioxide, nitrogen, oxygen, methane, ethylene, propylene, 1-butene, butane, and 1,3-butadiene.

- by Paul Scovazzo
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- Chemical Engineering, Thermodynamics, Carbon Dioxide, Modeling

h i g h l i g h t s " New results about ocean acidification in the southern region of South America. " First study of the effects of acidification on the physiology of a chilean bivalve. " Effects of ocean acidification on the mussel... more

- by Rodrigo Torres
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- Physiology, Climate Change, Carbon Dioxide, Multidisciplinary

Experimental and theoretical flux models have been developed to reveal the influence of sun flecks and increasing CO 2 concentrations on the energy and entropy balances of the leaf. The rapid and wide range of fluctuations in light intensity under field conditions were simulated in a climatic gas exchange chamber and we determined the energy and entropy balance of the leaf based on radiation and gas exchange measurements. It was estimated that the energy of photosynthetic active radiation (PAR) accounts for half of transpiration, which is the main factor responsible for the exportation of the entropy generated in photosynthesis (S g) out of the leaf in order to maintain functional the photosynthetic machinery. Although the response of net photosynthetic production to increasing concentrations of CO 2 under fluctuating light is similar to that under continuous light, rates of transpiration respond slowly to changes of light intensity and are barely affected by the concentration of CO 2 in the range of 260-495 ppm, in which net photosynthesis increases by more than 100%. The analysis of the results confirms that future increases of CO 2 will improve the efficiency of the conversion of radiant energy into biomass, but will not reduce the contribution of plant transpiration to the leaf thermal balance.

- by Dolores Marín
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- Engineering, Thermodynamics, Carbon Dioxide, Photosynthesis

Distal renal tubular acidosis chronic hydronephrosis in children with The difference between the Pco~ of alkalinized urine and the Pco~ of blood has been proposed as an indirect means of assessing distal nephron H + secretion. Following oral bicarbonate loading and alkalinization of the urine to pH ~ 7.2, eight of nine children with chronic hydronephrosis and four children with idiopathic distal RTA had low (U-B)Pco.~ values when compared with seven normal subjects. This finding leads us to conclude that chronic hydronephrosis may cause a form of distal RTA which persists many years after surgical diversion procedures have been carried out.

- by Robert Hutcheon
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- Pediatrics, Carbon Dioxide, Adolescent, Child

Properties of concentration waves of solutes affected by nonlinear sorption, precipitation/ dissolution and homogeneous reactions in the mobile and stationary phases are established when the number of phases is constant. These properties essentially depend on the structure of a stoichiometric matrix which describes the chemical interactions. A reduction procedure of the stoichiometric matrix gives the number of waves or peaks together with their propagation velocities, and the retardation factors of species at trace levels. The location of the peaks and their broadening behavior due to the nonlinear equilibria are estimated. The number of waves and the properties of suitable linear combinations of concentrations provide a method for discriminating among rival interaction mechanisms irrespective of the equilibrium constants. This cannot be done using conventional methods based on the comparison between numerical simulations and experimental curves. Bryant et al., 1986] are devoted to the consequences of the set of elementary interactions (homogeneous reactions, adsorption and/or exchange reactions, precipitation, dissolution, degassing processes, etc.) on the structure and properties of the corresponding breakthrough curves (BTC). Predicting qualitative properties of BTCs or elucidating the main features of an interaction mechanism from experimental BTCs can be performed using numerical computer codes. Unfortunately, these calculations can be time consuming and they require that the interaction parameters (i.e., equilibrium constants, kinetic constants, etc.) be known. There is thus a need for some general properties relating the structure (i.e., shape, number, and existence of waves or peaks) of the BTCs to the structure of the solid-fluid interaction mechanism. These properties should be as independent as possible of the interaction parameters, and they should help one both to discriminate among rival mecHanisms and to estimate the sensitivity of the shape of the BTCs to physicochemical parameters. This first of two papers describes the underlying concepts

- by Michel Sardin
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- Environmental Engineering, Civil Engineering, Water resources, Carbon Dioxide