Total CO2 Concentration Research Articles

Equilibrium WO3 concentration in the Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system

The Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system is a typical system in tungsten extractive metallurgy used in the preparation and purification of ammonium tungstate solution. To determine an appropriate solution composition to optimize these processes, a thermodynamic model combined with the Pitzer activity equations was developed. This model allowed us to predict the dependence of the equilibrium WO3 concentration on the compositions of the solution in the Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system. Thermodynamic analyses clarified the stable regions of CaCO3 and CaWO4 in the Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system and indicated that increasing both the total NH3 and total CO2 concentrations is beneficial for increasing the equilibrium WO3 concentration. The experimental results confirm that the thermodynamic model offers a means of predicting the equilibrium concentrations of species in the system. Furthermore, the equilibrium WO3 concentrations of the solution of the Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system at 298.15 K have been predicted at different total CO2 concentrations, as well as different total NH3 to total CO2 concentration ratios. Thus, the findings of this study will not only help determine the appropriate composition of the leaching system for preparing ammonium tungstate solutions, but also provide a reference for purifying ammonium tungstate solutions.

Deceptive sustainability: Cognitive bias in people's judgment of the benefits of CO2 emission cuts

People's beliefs in the actions necessary to reduce anthropogenic carbon dioxide (CO2) emissions are important to public policy acceptability. The current paper addressed beliefs concerning how periods of small emission cuts contribute to the total CO2 concentration in the atmosphere, by asking participants to rate the atmospheric CO2 concentration for various time periods and emission rates. The participants thought that a time period with higher emission rates combined with a period of lower emission rates generates less atmospheric CO2 in total, compared to the period with high emission rates alone – demonstrating a negative footprint illusion (Study 1). The participants appeared to base their CO2 estimates on the average, rather than on the accumulated sum, of the two periods' emissions – i.e. an averaging bias (Study 2). Moreover, the effect was robust to the wordings of the problem presented to the participants (Study 3). Together, these studies suggest that the averaging bias makes people exaggerate the benefits of small emission cuts. The averaging bias could make people willing to accept policies that reduce emission rates although insufficiently to alleviate global warming.

A high carbon content of the Hawaiian mantle from olivine-hosted melt inclusions

Abstract The deep mantle carbon content and flux are fundamental quantities in understanding global volatile cycles and distributions. Here, we present CO2 concentrations measured in 407 olivine-hosted melt inclusions from Hualalai, Kilauea, Koolau, Loihi, and Mauna Loa to constrain the Hawaiian mantle CO2 content and flux. Quantification of melt inclusion CO2 is complicated by the ubiquitous presence of vapor or “shrinkage” bubbles. The contribution from exsolved shrinkage bubble CO2 was determined from the measured bubble size and a CO2 equation of state, and added to the dissolved CO2 to reconstruct total melt inclusion CO2 concentrations. Bubbles typically contain ∼90% of melt inclusion C, much of which may be sequestered in precipitated phases on bubble walls, and thus not amenable to measurement by Raman spectroscopy. Based on our dataset of total (dissolved + bubble) CO2 concentrations, we estimate that parental melts from the five Hawaiian volcanoes have CO2 concentrations ranging from 3900 to 10,000 ppm CO2. Among the active volcanoes, CO2 concentrations decrease to the northwest, likely reflecting mantle source heterogeneity, although differences in CO2 degassing related to the relative depths of the magma chambers may also play a role. Mantle sources of the Hawaiian volcanoes range from 380 to 480 ppm CO2 suggesting that the Hawaiian plume is at least a factor of ∼4 more C-rich than the upper mantle sampled by mid-ocean ridge basalts. This enrichment is likely due to the presence of recycled surficial C and/or C-rich primitive material in the Hawaiian mantle.

Carbon dioxide removal using low bicarbonate dialysis in rodents.

Extracorporeal carbon dioxide removal may be used to manage hypercapnia, but compared to dialysis, it's not widely available. A recent in vitro study showed that dialysis with low bicarbonate dialysates removes CO2. To show that bicarbonate dialysis removes CO2 in an animal model to validate in-vitro findings and quantify the effect on arterial pH. Male Sprague-Dawley hypercapnic rats were dialyzed with either a conventional dialysate (PrismasolTM) or a bicarbonate-free dialysate (Bicarb0). The effect of dialysis on standard blood gases and electrolytes was measured. Partial pressure of CO2 and bicarbonate concentration in blood decreased significantly after exposure to Bicarb0 compared to PrismasolTM (filter outflow values 12.8 vs 81.1 mmHg; p < 0.01 for CO2 and 3.5 vs 22.0 mmol/L; p < 0.01 for bicarbonate). Total CO2 content of blood was reduced by 459 mL/L during dialysis with Bicarb0 (filter inflow 546 ± 91 vs filter outflow 87 ± 52 mL/L; p < 0.01), but was not significantly reduced with PrismasolTM. Bicarbonate dialysis removes CO2 at rates comparable to existing low-flow ECCO2R.

Investigation of CoCrMo material loss in a novel bio-tribometer designed to study direct cell reaction to wear and corrosion products

Wear and corrosion in total hip replacement negatively impact implant service-life and patient well-being. The aim of this study was to generate a statistical response surface of material loss using an apparatus, capable of testing the effect of wear and corrosion products in situ on cells, such as macrophages. The test chamber of a ball-on-flat tribometer operating inside a CO2 incubator was integrated with an electrochemical setup and adapted for cell culture work. A 20-test series, following a 2-level 3-factor design of experiments, was performed with a ceramic head in reciprocating rotational motion against a CoCrMo-alloy disc, under constant load. The lubricant was cell culture medium (RPMI-1640 + 10 vol% bovine serum). Response surfaces were generated, which statistically showed the influence of motion amplitude, load, and potential on the total mass loss and wear scar volume of the metallic discs. Potential had the highest impact on the total mass loss, while motion amplitude and load significantly influenced the wear scar volume. The concentrations of the alloy elements found in the lubricants reflected the bulk-alloy stoichiometry. The total concentration of Co released into the lubricant (2.3–63 ppm by total mass loss, 1.5 to 62 ppm by ICP-MS) corresponded well with the known range to trigger cell response. Tribocorrosion tests in the presence of cells and tissues, such as macrophages, lymphocytes and/or synovium, will be carried out in the future.

Combustion behavior of poplar (Populus adenopoda Maxim.) and radiata pine (Pinus radiata Don.) treated with a combination of styrene-acrylic copolymer and sodium silicate

Poplar (Populus adenopoda Maxim.) and radiata pine (Pinus radiata Don.) wood were treated with an aqueous solution containing styrene-acrylic copolymer (SAC) and sodium silicate (SS). The effects of this treatment on the thermal stability and combustion behavior of the wood were determined. Thermogravimetric (TG) analysis showed that treatment in the presence of SS resulted in earlier thermal degradation compared to samples untreated and treated with SAC alone. Cone calorimetry showed that treatment of wood with SAC alone resulted in increased total heat release, total smoke production, and CO and CO2 concentration. Wood treated with SAC/SS was more difficult to ignite as evidenced by longer ignition time and higher limiting oxygen index; however, the treatment did not reduce the production of smoke and carbon oxide. Scanning electron microscopy and energy dispersive X-ray analysis of residual char indicated that SS was mainly deposited in the lumina of vessel or tracheid, and SS distribution in wood was not uniform. These findings demonstrate that incorporation of SS retards the flame of SAC-treated wood; however, the fire risk is not reduced due to dense smoke and CO production.

Model Simulation of Cucumber Yield and Microclimate Analysis in a Semi-closed Greenhouse in China

Adequate greenhouse environmental management is very important for improving resource use efficiency and increasing vegetable yield. The objective of this study was to explore suitable climate and cultivation management for cucumber to achieve high yield and build optimal yield models in semi-closed greenhouses. A fruit cucumber cultivar Deltastar was grown over 4 years in greenhouse and weekly data of yields (mean, highest and lowest) and environmental variables, including total radiation, air temperature, relative humidity, and carbon dioxide (CO2) concentration were collected. Regression analyses were applied to develop the relationships and build best regression models of yields with environmental variables using the first 2 years of data. Data collected in years 3 and 4 were used for model validation. Results showed that total radiation, nutrient, temperature, CO2 concentration, and average nighttime relative humidity had significant correlations with cucumber yields. The best regression models fit the mean, lowest, and highest yields very well with R2 values of 0.67, 0.66, and 0.64, respectively. Total radiation and air temperature had the most significant contributions to the variations of the yields. Our results of this study provide useful information for improving greenhouse climate management and yield forecast in semi-closed greenhouses.

Rootstocks influence the salt tolerance of Kinnow mandarin trees by altering the antioxidant defense system, osmolyte concentration, and toxic ion accumulation

Rootstocks are a vital element of commercial citrus production. A varied level of salinity tolerance has been described for citrus rootstock cultivars, however, the effects of the rootstock can be scion-dependent. Our objective was to determine if rootstock selection has an influence on the salt-tolerance of 2-year-old Kinnow mandarin plants grafted onto two salt-sensitive (Carrizo citrange and Sanchton citrumello) and two salt-tolerant (Rangpur lime and Rubidoux) rootstock cultivars. Kinnow mandarin scion was grafted on these four rootstocks and irrigated with water containing 0, 30, 60, 90, or 120 mM NaCl. At the end of the experiment (90 days of salinization) growth, leaf gas exchange and chlorophyll fluorescence parameters, leaf and root Cl and Na concentrations, and parameters related to the antioxidant system were measured. Under salinity stress, plants grafted on salt-tolerant rootstocks had less reduction in plant biomass, total chlorophyll content, photosynthesis rate, stomatal conductance, and internal CO2 concentration as compared to the plants grafted on salt-sensitive rootstocks. Similarly, plants with salt-tolerant rootstocks had lower reactive oxygen species, suggesting enhanced activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, guaiacol peroxidase, and glutathione reductase), and higher accumulation of osmolytes (proline and glycinebetaine). In addition, for plants with salt-tolerant rootstocks the levels of Na and Cl were higher in roots while lower in leaves; the opposite was the case for plants grafted on salt-sensitive rootstocks. Therefore, the selection of the rootstock can enhance the salt-tolerance potential by enhancing antioxidant activities, increasing concentrations of osmoprotectants, and limiting leaf levels of Na and Cl. Kinnow mandarin plants grafted on Rangpur lime or Rubidoux showed more salt tolerance than those on Carrizo citrange or Sanchton citrumello.

The Role of the Ecosystem Engineer, the Leaf‐Cutter Ant Atta cephalotes, on Soil CO2 Dynamics in a Wet Tropical Rainforest

AbstractLeaf‐cutter ants are dominant herbivores that disturb the soil and create biogeochemical hot spots. We studied how leaf‐cutter ant Atta cephalotes impacts soil CO2 dynamics in a wet Neotropical forest. We measured soil CO2 concentration monthly over 2.5 years at multiple depths in nonnest and nest soils (some of which were abandoned during the study) and assessed CO2 production. We also measured nest and nonnest soil efflux, nest vent efflux, and vent concentration. Nest soils exhibited lower CO2 accumulation than nonnest soils for the same precipitation amounts. During wet periods, soil CO2 concentrations increased across all depths, but were significantly less in nest than in nonnest soils. Differences were nonsignificant during drier periods. Surface efflux was equal across nest and nonnest plots (5 μmol CO2 m−2 s−1), while vent efflux was substantially (103 to 105 times) greater, a finding attributed to free convection and sporadic forced convection. Vent CO2 concentrations were less than in soil, suggesting CO2 efflux from the soil matrix into the nest. Legacy effects in abandoned nests were still observable after more than two years. These findings indicate that leaf‐cutter ant nests provide alternative transport pathways to soil CO2 that increase total emissions and decrease soil CO2 concentrations, and have a lasting impact. Estimated total nest‐soil CO2 emissions were 15 to 60% more than in nonnest soils, contributing 0.2 to 0.7% to ecosystem‐scale soil emissions. The observed CO2 dynamics illuminate the significant carbon footprint of ecosystem engineer Atta cephalotes and have biogeochemical implications for rainforest ecosystems.

Application of a laser-based spectrometer for continuous in situ measurements of stable isotopes of soil CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; in calcareous and acidic soils

Abstract. The short-term dynamics of carbon and water fluxes across the soil–plant–atmosphere continuum are still not fully understood. One important constraint is the lack of methodologies that enable simultaneous measurements of soil CO2 concentration and respective isotopic composition at a high temporal resolution for longer periods of time. δ13C of soil CO2 can be used to derive information on the origin and physiological history of carbon, and δ18O in soil CO2 aids in inferring the interaction between CO2 and soil water. We established a real-time method for measuring soil CO2 concentration, δ13C and δ18O values across a soil profile at higher temporal resolutions (0.05–0.1 Hz) using an off-axis integrated cavity output spectroscopy (OA-ICOS). We also developed a calibration method correcting for the sensitivity of the device against concentration-dependent shifts in δ13C and δ18O values under highly varying CO2 concentration. The deviations of measured data were modelled, and a mathematical correction model was developed and applied for correcting the shift. By coupling an OA-ICOS with hydrophobic but gas-permeable membranes placed at different depths in acidic and calcareous soils, we investigated the contribution of abiotic and biotic components to total soil CO2 release. We found that in the calcareous Gleysol, CO2 originating from carbonate dissolution contributed to the total soil CO2 concentration at detectable degrees, potentially due to CO2 evasion from groundwater. The 13C-CO2 of topsoil at the calcareous soil site was found reflect δ13C values of atmospheric CO2, and the δ13C of topsoil CO2 at the acidic soil site was representative of the biological respiratory processes. δ18O values of CO2 in both sites reflected the δ18O of soil water across most of the depth profile, except for the 80 cm depth at the calcareous site where a relative enrichment in 18O was observed.

The structural-phase state and magnetoresistive properties of thin film alloys obtained by co-evaporated Cu and Co

Abstract This research presents the study on the structural-phase states and magnetoresistive properties of thin nanogranular film alloys based on Cu and Co with a total concentration of Co in the range of 15 ≤ x ≤ 71 at%. The analyses for the unannealed and annealed thin films with a thickness d = 20 nm, have been performed. The films have been annealed in the temperature range from 300 to 800 K for 20 min. It found that the heat treatment within the range from 600 to 800 K led to an increase in the magnetoresistance and coercive force due to the growth of Co granules size under heat treatment and partial decomposition of the fcc-Cu(Co) solid solution. The highest magnitudes of the magnetoresistance were found in the as-deposited film alloys featured by the total concentration of Co x = 21 at%, which consist of Cu(Co) solid solution made of fcc-Cu and superparamagnetic Co granules (size L = 2 ÷ 5 nm). Interestingly, the thin film alloys with an increased concentration of Co x ≥ 50 at% exhibited anisotropic magnetoresistance.

Mn Porphyrin-Based Redox Active Drugs As Novel Anti-Adhesive and Anti-Inflammatory Agents Targeting Sickle Red Blood Cell Oxidative Damage In Vivo

In sickle cell disease (SCD), painful vaso-occlusive crises and end-organ damage are caused by occlusion of the vessels due largely to sickle red blood cell (RBC) adhesion to both the endothelium and adherent leukocytes. RBC oxidative damage caused by continuous endogenous and exogenous oxidative stress may participate in the occurrence of vaso-occlusive crises.We have evaluated the effects of scavenging reactive oxygen species (ROS) in sickle RBCs on cell adhesion and vaso-occlusion in a humanized mouse model of vaso-occlusion in vivo analyzed by intravital microscopy. To scavenge RBC ROS, we used our manganese porphyrin-based superoxide dismutase (SOD) mimics MnTnBuOE-2-PyP5+ (MnBuOE) and MnTE-2-PyP5+ (MnE), powerful catalysts of superoxide dismutation, and reductants of peroxynitrite, peroxide and hypochlorite. Intravital microscopy observations of enflamed vessels visible through dorsal skin-fold window chamber implants was performed after the inflammatory trigger of tumor necrosis factor alpha (TNFα) to induce vaso-occlusion in transgenic sickle mice followed by subcutaneous injection of MnBuOE at 0.1, 0.2 or 2 mg/kg, or MnE at 0.5 or 2 mg/kg.Treatment of sickle mice with only one dose of 0.1, 0.2 and 2 mg/kg MnBuOE decreased dose-dependently adhesion of both sickle cells and leukocytes in enflamed vessels by 68±4% (p<0.01), 85±2.3% (p<0.01) and 89±4.3% (p<0.01), respectively, compared with vehicle-treated sickle mice. MnBuOE at 0.1, 0.2 and 2 mg/kg also caused significant and dose-dependent reduction in leukocyte rolling flux (p<0.05). Similar inhibitory benefits were obtained when MnE was administered to TNFa-treated sickle mice. MnE at 0.5 and 2 mg/kg significantly decreased the number of adherent sickle cells and leukocytes by 76±8.6% (p<0.01) and 92±2.5% (p<0.01), respectively, and leukocyte rolling flux (p<0.01) compared to vehicle-treated animals. The effect of these two SOD mimics on sickle RBCs and leukocyte adhesion, and leukocyte rolling flux was rapid, because a decline in cell adhesion and leukocyte rolling flux were already detectable within the first 15 minutes after injection of the compounds. In contrast, cell adhesion and leukocyte rolling flux were already pronounced 15 minutes following vehicle injection. Reduced cell adhesion to the endothelium by the SOD mimics resulted in improved microcirculatory blood flow in sickle mice. These favorable effects on cell adhesion and vaso-occlusion following SOD mimic treatment were indeed due at least to the significant decrease in sickle RBC ROS levels compared to vehicle-treated mice (p<0.001).The long-term anti-adhesive and anti-inflammatory effects of MnBuOE and MnE in sickle mice were next examined. Subcutaneous administration for 28 days of MnBuOE at 0.1 and 0.5 mg/kg inhibited significantly adhesion of RBCs and leukocytes in enflamed venules by 34±13% (p<0.05) and 69±3.5% (p<0.001), respectively, and leukocyte rolling flux (p<0.001) compared to vehicle-treated sickle mice. Subcutaneous injection of MnE at 0.5 and 1 mg/kg for 28 days also had significant effect on sickle cell and leukocyte adhesion (p<0.01), and leukocyte rolling flux (p<0.01). In addition, venous blood gases were significantly improved by the SOD mimics. The levels of partial pressure of Carbon dioxide (pCO2), partial pressure of oxygen (pO2), base excess of the extracellular fluid (BEecf), bicarbonate (HCO3-) concentration, total CO2 (TCO2) concentration, and the indicators of hypoxia, hemoglobin saturation of oxygen (sO2) and lactate, became close to or within the normal ranges (p<0.05) in sickle mice treated with 1 mg/kg MnE. MnBuOE at 0.1 mg/kg showed only a trend toward an increase in venous blood gases, with a significant decrease in lactate (p<0.05). Leukocytosis in sickle mice treated with the SOD mimics was also alleviated. A significant drop in leukocyte (p<0.05), neutrophil (p<0.01), lymphocyte (p<0.05) and monocyte (p<0.05) counts was detected in sickle mice treated with either 0.1 mg/kg MnBuOE or 1 mg/kg MnE. These beneficial therapeutic outcomes induced by the SOD mimics were due at least in part to a decline in RBC ROS levels (p<0.001) and RBC phosphatidylserine surface exposure (p<0.05), an eryptosis marker.These results suggest that our SOD mimics may represent a valuable novel therapeutic intervention for not only vaso-occlusive crises, but inflammation as well, that should be further evaluated in patients with SCD. DisclosuresNo relevant conflicts of interest to declare.

Low Irradiation Dose for Sorghum Seed Sterilization: Hydroponic Fodder System and In Vitro Study

The purpose of this study was to to evaluate the influence of low gamma irradiation dose on growth performance, in vitro gas production and rumen fermentation product of sorghum hydroponic fodder (SHF) to utilize them in ruminant diets. Three polyethylene packages of Samurai 2 sorghum seeds were exposed at 25oC gamma irradiation in gamma cell (Co-60) at doses of 100, 200 and 300 Gy in the presence of air. Samples were then referigated (&lt; 5oC) before planting. All seeds were planted in nutrient film technique hydroponic system. This study used Completely Randomized Design with four replications The observed parameters were total fresh yield, plant height and coversion ratio from seeds to SHF. In vitro gas test evaluation was done to compare all treatments with sorghum straw. The observed parameters were total gas production, kinetics gas, CH4 concentration, CO2 concentration and rumen fermentation products. Results showed that lower irradiation dose for seeds sterilization decreased plant height and total fresh yield on SHF production. In vitro total gas production of all SHF treatment was higher (p&lt;0.05) than sorghum straw (control) at 2-48 h time of incubation. Gamma irradiation dose of 200 and 300 Gy on SHF seeds sterilization decreased (p&lt;0.05) in vitro CH4 concentration for 19.51 and 15.43% respectively compared to SHF control (hypochlorite sterilization). In the same dose, seeds sterilization with gamma irradiation increased (p&lt;0.05) CO2:CH4 ratio by 23.46 and 20.73% respectively compared to SHF control. The treatment of 100 Gy gamma irradiation for seed sterilization also increased (p&lt;0.05) TVFA by 30.63% compared to sorghum straw. It was concluded that lower irradiation dose for seeds sterilization decreased growth performance of SHF. However, 100 Gy gamma irradiation increased in vitro total gas production.

Re-Evaluation of Total CO2 Concentration in Apparently Healthy Younger Adults

The initial assessment of acid-base status is usually based on the measurement of total CO₂ concentration ([TCO₂]) in venous blood, a surrogate for [HCO₃^–]. Previously, we posited that the reference limits of serum [TCO₂] in current use are too wide. Based on studies on the acid-base composition of normal subjects, we suggested that the reference limits of serum [TCO₂] at sea level be set at 23–30 mEq/L. To validate this proposal, we queried the University of California at Los Angeles (UCLA’s) Integrated Clinical and Research Data Repository, a database containing information on 4.5 million patients seen at UCLA from 2006 to the present. Criteria for inclusion included adults (18–40 years of age), who were free of disorders that could affect acid-base balance, were not taking medications that could affect acid-base balance, and were seen for a routine medical examination or immunization in the outpatient setting. The number of individuals who met the inclusion criteria (52% female and 48% male) was 28,480, with a mean age of 28.9 ± 5.1 years. The mean serum [TCO₂] level was slightly higher in males than females, 26.6 ± 2.16 mEq/L vs. 25.0 ± 2.11 mEq/L (p < 0.05). Ninety-one percent of patient values were within the proposed 23–30 mEq/L range and 61.7% were within the 24–27 mEq/L range. These findings validate our proposal that the reference range of serum [TCO₂] in venous blood at sea level be narrowed to 23–30 mEq/L. Subjects with serum [TCO₂] outside this range might require assessment with a venous blood gas to exclude the presence of clinically important acid-base disorders.

Smoke suppression properties of Si-Al mesoporous structure on medium density fiberboard

In this article, smoke suppression of Si-Al mesoporous structure on medium density fiberboard (MDF) was investigated by cone calorimeter test (CCT), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and fourier transform infrared spectrometry (FTIR). The CCT results show that the Si-Al mesoporous structure can effectively decrease heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), smoke rate (SR), CO and CO2 concentration, etc. Particularly, the SR curves of MDF present that Si-Al mesoporous structure are considered to be a filter, which can net the solid particles and volatile flammable components in the smoke and fix onto wood fiber. Remarkably, the CO and CO2 concentration curves of MDF indicate that the Si-Al mesoporous structure has an excellent adsorption property, which can rapidly absorb CO and CO2 that generated in wood combustion process. On the other hand, the FTIR and TGA results reveal that the Si-Al mesoporous structure can significantly improve the structure of char residue.

Variations of Residual CO2 and Pressure in Conifer Woody Roots

In continuation of works on the determination of cyclic tree-stem CO2 efflux, vacuum-extracted gas samples of large woody roots of Siberian stone pine and Scots pine are studied. Laser photoacoustic gas analysis was used to obtain chronologies of CO2 and total pressure of gas components in root rings. Spectral and cross-spectral analyses reveal the cyclic character of variations in the chronologies. Such a behavior of the total pressure and CO2 content in large roots can testify to possible cyclic diffusion of CO2 from the roots into soil and then into the atmosphere, which can be considered as a new feature of autotroph respiration. An attempt is made to analyze results of some previous work on a similar subject based on cyclic CO2 efflux from large roots.

The Correlation of Serum Osteoprotegerin with Non-Traditional Cardiovascular Risk Factors and Arterial Stiffness in Patients with Pre-Dialysis Chronic Kidney Disease: Results from the KNOW-CKD Study.

BackgroundOsteoprotegerin (OPG) plays protective roles against the development of vascular calcification (VC) which greatly contributes to the increased cardiovascular events in patients with chronic kidney disease (CKD). The present study aimed to find the non-traditional, kidney-related cardiovascular risk factors correlated to serum OPG and the effect of serum OPG on the arterial stiffness measured by brachial ankle pulse wave velocity (baPWV) in patients with the pre-dialysis CKD.MethodsWe cross-sectionally analyzed the data from the patients in whom baPWV and the serum OPG were measured at the time of enrollment in a prospective pre-dialysis CKD cohort study in Korea.ResultsAlong with traditional cardiovascular risk factors such as age, diabetes mellitus, pulse pressure, and baPWV, non-traditional, kidney-related factors such as albuminuria, plasma level of hemoglobin, total CO2 content, alkaline phosphatase, and corrected calcium were independent variables for serum OPG in multivariate linear regression. Reciprocally, the serum OPG was positively associated with baPWV in multivariate linear regression. The baPWV in the 3rd and 4th quartile groups of serum OPG were higher than that in the 1st quartile group after adjustments by age, sex and other significant factors for baPWV in linear mixed model.ConclusionNon-traditional, kidney-related cardiovascular risk factors in addition to traditional cardiovascular risk factors were related to serum level of OPG in CKD. Serum OPG level was significantly related to baPWV. Our study suggests that kidney-related factors involved in CKD-specific pathways for VC play a role in the increased secretion of OPG into circulation in patients with CKD.Trial RegistrationClinicalTrials.gov Identifier: NCT01630486

Changes in hemolymph total CO2 content during the water-to-air respiratory transition of amphibiotic dragonflies.

Dragonflies (Odonata, Anisoptera) are amphibiotic; the nymph is aquatic and breathes water using a rectal gill before metamorphosing into the winged adult, which breathes air through spiracles. While the evolutionary and developmental transition from water breathing to air breathing is known to be associated with a dramatic rise in internal CO2 levels, the changes in blood-gas composition experienced by amphibiotic insects, which represent an ancestral air-to-water transition, are unknown. This study measured total CO2 (TCO2) in hemolymph collected from aquatic nymphs and air-breathing adults of Anax junius, Aeshna multicolor (Aeshnidae), Libellula quadrimaculata and Libellulaforensis (Libellulidae). Hemolymph PCO2 was also measured in vivo in both aeshnid nymphs and marbled crayfish (Procambarus fallax. f. virginalis) using a novel fiber-optic CO2 sensor. The hemolymph TCO2 of the pre- and early-final instar nymphs was found to be significantly lower than that of the air-breathing adults. However, the TCO2 of the late-final instar aeshnid nymphs was not significantly different from that of the air-breathing adults, despite the late-final nymphs still breathing water. TCO2 and PCO2 were also significantly higher in the hemolymph of early-final aeshnid nymphs compared with values for the water-breathing crayfish. Thus, while dragonfly nymphs show an increase in internal CO2 as they transition from water to air, from an evolutionary standpoint, the nymph's ability to breathe water is associated with a comparatively minor decrease in hemolymph TCO2 relative to that of the air-breathing adult.

Assessment of indoor air quality at an electronic cigarette (Vaping) convention

E-cigarette (vaping) conventions are public events promoting electronic cigarettes, in which indoor use of e-cigarettes is allowed. The large concentration of people using e-cigarettes and poor air ventilation can result in indoor air pollution. In order to estimate this worst-case exposure to e-cigarettes, we evaluated indoor air quality in a vaping convention in Maryland (MD), USA. Real-time concentrations of particulate matter (PM10) and real-time total volatile organic compounds (TVOCs), CO2 and NO2 concentrations were measured. Integrated samples of air nicotine and PM10 concentrations were also collected. The number of attendees was estimated to range from 75 to 600 at any single observation time. The estimated 24-h time-weighted average (TWA) PM10 was 1800 μg/m3, 12-fold higher than the EPA 24-h regulation (150 μg/m3). Median (range) indoor TVOCs concentration was 0.13 (0.04–0.3) ppm. PM10 and TVOC concentrations were highly correlated with CO2 concentrations, indicating the high number of people using e-cigarettes and poor indoor air quality. Air nicotine concentration was 125 μg/m3, equivalent to concentrations measured in bars and nightclubs. E-cigarette aerosol in a vaping convention that congregates many e-cigarette users is a major source of PM10, air nicotine and VOCs, impairing indoor air quality. These findings also raise occupational concerns for e-cigarette vendors and other venue staff workers.

Weak hydrothermal carbonation of the Ongeluk volcanics: evidence for low CO2 concentrations in seawater and atmosphere during the Paleoproterozoic global glaciation

It was previously revealed that the total CO2 concentration in seawater decreased during the Late Archean. In this paper, to assess the secular change of total CO2 concentration in seawater, we focused on the Paleoproterozoic era when the Earth experienced its first recorded global glaciation. The 2.4 Ga Ongeluk Formation outcrops in the Kaapvaal Craton, South Africa. The formation consists mainly of submarine volcanic rocks that have erupted during the global glaciation. The undeformed lavas are mostly carbonate-free but contain rare disseminated calcites. The carbon isotope ratio of the disseminated calcite (δ13Ccc vs. VPDB) ranges from − 31.9 to − 13.2 ‰. The relatively low δ13Ccc values clearly indicate that the carbonation was partially contributed by 13C-depleted CO2 derived from decomposition of organic matter beneath the seafloor. The absence of δ13Ccc higher than − 13.2‰ is consistent with the exceptionally 13C-depleted CO2 in the Ongeluk seawater during glaciation. The results suggest that carbonation occurred during subseafloor hydrothermal circulation just after the eruption of the lavas. Previously, it was reported that the carbonate content in the uppermost subseafloor crust decreased from 3.2 to 2.6 Ga, indicating a decrease in total CO2 concentration in seawater during that time. However, the average CO2 (as carbonate) content in the Ongeluk lavas (< 0.001 wt%) is much lower than those of 2.6 Ga representatives and even of modern equivalents. This finding suggests that the total CO2 concentration in seawater further decreased during the period between 2.6 and 2.4 Ga. Thus, the very low content of carbonate in the Ongeluk lavas is probable evidence for the extremely low CO2 concentration in seawater during the global glaciation. Considering that the carbonate content of the subseafloor crusts also shows a good correlation with independently estimated atmospheric pCO2 levels through the Earth history, it seem highly likely that the low carbonate content in the Ongeluk lavas reflects the low atmospheric pCO2 at that time. We conclude that the continuous decrease in CO2 concentration of seawater/atm. from 3.2 Ga was one of the contributing factors to the Paleoproterozoic global glaciation.