CO2 Partial Pressure Research Articles

The conducted vascular response as a mediator of hypercapnic cerebrovascular reactivity: A modelling study

It is well established that the cerebral blood flow (CBF) shows exquisite sensitivity to changes in the arterial blood partial pressure of CO2 (Pa,CO2), which is reflected by an index termed cerebrovascular reactivity. In response to elevations in Pa,CO2 (hypercapnia), the vessels of the cerebral microvasculature dilate, thereby decreasing the vascular resistance and increasing CBF. Due to the challenges of access, scale and complexity encountered when studying the microvasculature, however, the mechanisms behind cerebrovascular reactivity are not fully understood. Experiments have previously established that the cholinergic release of the Acetylcholine (ACh) neurotransmitter in the cortex is a prerequisite for the hypercapnic response. It is also known that ACh functions as an endothelial-dependent agonist, in which the local administration of ACh elicits local hyperpolarization in the vascular wall; this hyperpolarization signal is then propagated upstream the vascular network through the endothelial layer and is coupled to a vasodilatory response in the vascular smooth muscle (VSM) layer in what is known as the conducted vascular response (CVR). Finally, experimental data indicate that the hypercapnic response is more strongly correlated with the CO2 levels in the tissue than in the arterioles. Accordingly, we hypothesize that the CVR, evoked by increases in local tissue CO2 levels and a subsequent local release of ACh, is responsible for the CBF increase observed in response to elevations in Pa,CO2. By constructing physiologically grounded dynamic models of CBF and control in the cerebral vasculature, ones that integrate the available knowledge and experimental data, we build a new model of the series of signalling events and pathways underpinning the hypercapnic response, and use the model to provide compelling evidence that corroborates the aforementioned hypothesis. If the CVR indeed acts as a mediator of the hypercapnic response, the proposed mechanism would provide an important addition to our understanding of the repertoire of metabolic feedback mechanisms possessed by the brain and would motivate further in-vivo investigation. We also model the interaction of the hypercapnic response with dynamic cerebral autoregulation (dCA), the collection of mechanisms that the brain possesses to maintain near constant CBF despite perturbations in pressure, and show how the dCA mechanisms, which otherwise tend to be overlooked when analysing experimental results of cerebrovascular reactivity, could play a significant role in shaping the CBF response to elevations in Pa,CO2. Such in-silico models can be used in tandem with in-vivo experiments to expand our understanding of cerebrovascular diseases, which continue to be among the leading causes of morbidity and mortality in humans.

Myeloid Zfhx3 deficiency protects against hypercapnia-induced suppression of host defense against influenza A virus.

Hypercapnia, elevation of the partial pressure of CO2 in blood and tissues, is a risk factor for mortality in patients with severe acute and chronic lung diseases. We previously showed that hypercapnia inhibits multiple macrophage and neutrophil antimicrobial functions and that elevated CO2 increases the mortality of bacterial and viral pneumonia in mice. Here, we show that normoxic hypercapnia downregulates innate immune and antiviral gene programs in alveolar macrophages (AMØs). We also show that zinc finger homeobox 3 (Zfhx3) - a mammalian ortholog of zfh2, which mediates hypercapnic immune suppression in Drosophila - is expressed in mouse and human macrophages. Deletion of Zfhx3 in the myeloid lineage blocked the suppressive effect of hypercapnia on immune gene expression in AMØs and decreased viral replication, inflammatory lung injury, and mortality in hypercapnic mice infected with influenza A virus. To our knowledge, our results establish Zfhx3 as the first known mammalian mediator of CO2 effects on immune gene expression and lay the basis for future studies to identify therapeutic targets to interrupt hypercapnic immunosuppression in patients with advanced lung disease.

CMEMS-LSCE: a global, 0.25°, monthly reconstruction of the surface ocean carbonate system

Abstract. Observation-based data reconstructions of global surface ocean carbonate system variables play an essential role in monitoring the recent status of ocean carbon uptake and ocean acidification, as well as their impacts on marine organisms and ecosystems. So far, ongoing efforts are directed towards exploring new approaches to describe the complete marine carbonate system and to better recover its fine-scale features. In this respect, our research activities within the Copernicus Marine Environment Monitoring Service (CMEMS) aim to develop a sustainable production chain of observation-derived global ocean carbonate system datasets at high space–time resolutions. As the start of the long-term objective, this study introduces a new global 0.25∘ monthly reconstruction, namely CMEMS-LSCE (Laboratoire des Sciences du Climat et de l'Environnement) for the period 1985–2021. The CMEMS-LSCE reconstruction derives datasets of six carbonate system variables, including surface ocean partial pressure of CO2 (pCO2), total alkalinity (AT), total dissolved inorganic carbon (CT), surface ocean pH, and saturation states with respect to aragonite (Ωar) and calcite (Ωca). Reconstructing pCO2 relies on an ensemble of neural network models mapping gridded observation-based data provided by the Surface Ocean CO2 ATlas (SOCAT). Surface ocean AT is estimated with a multiple-linear-regression approach, and the remaining carbonate variables are resolved by CO2 system speciation given the reconstructed pCO2 and AT; 1σ uncertainty associated with these estimates is also provided. Here, σ stands for either the ensemble standard deviation of pCO2 estimates or the total uncertainty for each of the five other variables propagated through the processing chain with input data uncertainty. We demonstrate that the 0.25∘ resolution pCO2 product outperforms a coarser spatial resolution (1∘) thanks to higher data coverage nearshore and a better description of horizontal and temporal variations in pCO2 across diverse ocean basins, particularly in the coastal–open-ocean continuum. Product qualification with observation-based data confirms reliable reconstructions with root-mean-square deviation from observations of less than 8 %, 4 %, and 1 % relative to the global mean of pCO2, AT (CT), and pH. The global average 1σ uncertainty is below 5 % and 8 % for pCO2 and Ωar (Ωca), 2 % for AT and CT, and 0.4 % for pH relative to their global mean values. Both model–observation misfit and model uncertainty indicate that coastal data reproduction still needs further improvement, wherein high temporal and horizontal gradients of carbonate variables and representative uncertainty from data sampling would be taken into account as a priority. This study also presents a potential use case of the CMEMS-LSCE carbonate data product in tracking the recent state of ocean acidification. The data associated with this study are available at https://doi.org/10.14768/a2f0891b-763a-49e9-af1b-78ed78b16982 (Chau et al., 2023).

Genomic structural variation is associated with hypoxia adaptation in high-altitude zokors.

Zokors, an Asiatic group of subterranean rodents, originated in lowlands and colonized high-elevational zones following the uplift of the Qinghai-Tibet plateau about 3.6 million years ago. Zokors live at high elevation in subterranean burrows and experience hypobaric hypoxia, including both hypoxia (low oxygen concentration) and hypercapnia (elevated partial pressure of CO2). Here we report a genomic analysis of six zokor species (genus Eospalax) with different elevational ranges to identify structural variants (deletions and inversions) that may have contributed to high-elevation adaptation. Based on an assembly of a chromosome-level genome of the high-elevation species, Eospalax baileyi, we identified 18 large inversions that distinguished this species from congeners native to lower elevations. Small-scale structural variants in the introns of EGLN1, HIF1A, HSF1 and SFTPD of E. baileyi were associated with the upregulated expression of those genes. A rearrangement on chromosome 1 was associated with altered chromatin accessibility, leading to modified gene expression profiles of key genes involved in the physiological response to hypoxia. Multigene families that underwent copy-number expansions in E. baileyi were enriched for autophagy, HIF1 signalling and immune response. E. baileyi show a significantly larger lung mass than those of other Eospalax species. These findings highlight the key role of structural variants underlying hypoxia adaptation of high-elevation species in Eospalax.

Development of a genetic engineering toolbox for syngas-utilizing acetogen Clostridium sp. AWRP

BackgroundClostridium sp. AWRP (AWRP) is a novel acetogenic bacterium isolated under high partial pressure of carbon monoxide (CO) and can be one of promising candidates for alcohol production from carbon oxides. Compared to model strains such as C. ljungdahlii and C. autoethanogenum, however, genetic manipulation of AWRP has not been established, preventing studies on its physiological characteristics and metabolic engineering.ResultsWe were able to demonstrate the genetic domestication of AWRP, including transformation of shuttle plasmids, promoter characterization, and genome editing. From the conjugation experiment with E. coli S17-1, among the four replicons tested (pCB102, pAMβ1, pIP404, and pIM13), three replicated in AWRP but pCB102 was the only one that could be transferred by electroporation. DNA methylation in E. coli significantly influenced transformation efficiencies in AWRP: the highest transformation efficiencies (102–103 CFU/µg) were achieved with unmethylated plasmid DNA. Determination of strengths of several clostridial promoters enabled the establishment of a CRISPR/Cas12a genome editing system based on Acidaminococcus sp. BV3L6 cas12a gene; interestingly, the commonly used CRISPR/Cas9 system did not work in AWRP, although it expressed the weakest promoter (C. acetobutylicum Pptb) tested. This system was successfully employed for the single gene deletion (xylB and pyrE) and double deletion of two prophage gene clusters.ConclusionsThe presented genome editing system allowed us to achieve several genome manipulations, including double deletion of two large prophage groups. The genetic toolbox developed in this study will offer a chance for deeper studies on Clostridium sp. AWRP for syngas fermentation and carbon dioxide (CO2) sequestration.

Highly efficient, coke-free electrolysis of dry CO2 in solid oxide electrolysis cells

Dry CO2 electrolysis in solid oxide electrolysis cells (SOECs), a highly efficient, versatile method for converting CO2 into value-added products, is critically limited by carbon deposition on Ni-based fuel electrodes. We achieved efficient, coke-free CO2 electrolysis using SOECs by elaborately controlling the local gas environments. Multilayered electrode microstructures were systematically engineered to facilitate mass transport and maintain the CO partial pressure below the threshold for solid carbon formation. A fuel-electrode-supported cell with an improved electrode microstructure operated stably for 500 h without coking at 0.50 A cm−2 and 700 °C, whereas conventional ones failed immediately. Multiphysics modeling coupled with three-dimensional quantitative microstructural analysis confirmed our improved electrode successfully mitigated carbon deposition. Furthermore, the enhanced electrode substantially lowered the overpotential and increased the CO production rate by > 50 %. These results highlight the feasibility of coke-free dry CO2 electrolysis in SOECs using commercially viable materials by controlling the electrode transport properties.

Impact of Marine Heatwaves on Air‐Sea CO2 Flux Along the US East Coast

AbstractMarine heatwaves (MHWs) are extremely warm ocean temperature events that significantly affect marine environments, but their effects on the coastal carbonate system are still uncertain. In this study, we systematically quantify MHWs' impacts on air‐sea carbon dioxide (CO2) flux anomalies (FCO2′) in the Mid‐Atlantic Bight (MAB) and South Atlantic Bight (SAB) from 1992 to 2020. During the longest MHW in both regions, oceanic CO2 uptake capabilities substantially decreased, primarily due to significant increases in the seawater partial pressure of CO2 (pCO2sea). For all cases, MHWs played a more significant role in driving pCO2sea changes in the MAB than the SAB, where non‐thermal drivers dominated pCO2sea variability. In the MAB, weakened wind speeds related to wintertime atmospheric perturbations increase ocean temperatures and pCO2sea, further reducing CO2 uptake during winter MHWs. This work is the first to connect extreme temperatures to coastal air‐sea CO2 fluxes. The reduction in CO2 absorption noted during MHWs in this study has important implications for coastal regions to act as continued sinks for excess CO2 emissions in the atmosphere.

Physiological and Anesthetic Considerations of Safe and Optimal Pneumoperitoneal Pressures for Laparoscopic Surgeries in Children.

In the era of minimally invasive surgeries, pediatric laparoscopic surgeries are now becoming the standard of care. In this study, we aim to determine the safe and optimal pneumoperitoneal pressures (PPs) for laparoscopic surgery in children aged 1-5 years, along with the technical ease for the surgeon. Prospective, randomized, single-blinded study was conducted at SGPGI Lucknow. Children aged 1-5 years were randomized into Group I (n = 24): PP = 6-8 mmHg and Group II: (PP) = 9-10 mmHg. Hemodynamic, ventilatory, and blood gas changes were measured before CO2 insufflation (T0), 20 min after insufflation (T1), before desufflation (T2), and 10 min after desufflation (T3). Surgeon's technical ease of surgery, postoperative pain, the requirement of rescue analgesia, time to resume feeding, and complications were recorded and analyzed. Paired t-test, Mann-Whitney test, and Wilcoxon signed-rank test were used for nonparametric/parametric data. Chi-square/Fisher's test was used for nominal data. Partial pressure of CO2 (PaCO2) was significantly higher in Group II at T1, T2, and T3, requiring frequent changes in ventilatory settings. Postoperative pain scores were higher in Group II at 1, 6, and 12 h, requiring rescue analgesia. Surgeon's scores and hemodynamics were similar in both groups. Higher PP in Group II caused significant changes in PaCO2, end-tidal CO2, and postoperative pain requiring rescue analgesia, but blood gas changes were clinically insignificant and there were no significant changes in hemodynamic parameters. Since the surgeon's ease of performing surgery was similar in both groups, we recommend that laparoscopy in children aged 1-5 years can be started with lower PPs of 6-8 mmHg, which can be increased if needed based on the surgeon's comfort and the patient's body habitus.

Cyclic CO2 absorption/desorption property of Li3NaSiO4 under the partial pressure of CO2 for practical applications.

The temperature for realizing the cyclic CO2 absorption/desorption property of Li3NaSiO4 by repetition of switching a CO2/N2 gas mixture and N2 with a partial pressure of CO2, P(CO2), of 0.1 bar was optimized using the pseudo van't Hoff plot of LiNaCO3 + Li2SiO3 ↔ Li3NaSiO4 + CO2 prepared by thermogravimetry at various P(CO2) values.

Respiratory and muscular effort during pre-slaughter stress affect Nile tilapia fillet quality.

Nile Tilapia (Oreochromis niloticus) management procedures are directly linked to the final quality of the product. The aim of this study was to evaluate the effect of pre-slaughter density and different stunning methods on biochemical, respiratory and muscle injury parameters associated with quality and sensory characteristics of Nile tilapia fillets. Fish with an average weight of 762±105 g were used, first collected called the control group. The experiment was conducted in a 2 × 2 factorial scheme, with two densities (50 and 300 kg of live weight m-3) and two stunning methods thus totaling four treatments, with 15 repetitions per treatment totaling 75 fish sampled. Blood gas analysis, evaluation of biochemical parameters, analysis of meat quality and sensory analysis were carried out. For blood gas, biochemical and enzymatic parameters, the highest values were obtained for the density of 300 kg m-3 and asphyxia method: partial pressures of CO2; glucose and lactate, the highest values presented were 268.98 and 11.33 mg dL-1 respectively. As well as enzymatic activities, Creatinine kinase (CPK); Creatinine kinase isoenzyme (CKMB) showed higher values (768.93 and 1078.98 mg dL-1 respectively) in the higher density and asphyxia method. Conversely, when evaluating the quality parameters, the highest values were observed for lower density and thermonarcosis. High depuration density (300 kg m-3), combined with the asphyxiation stunning method, promotes changes in respiratory dynamics and provides greater stress, less firm fillet texture and greater weight loss due to cooking, as well as changes in creatine kinase (CK) and its CK-MB isoenzyme, demonstrating greater muscle damage. On the other hand, the density of 50 kg m-3 during pre-slaughter, combined with the method of stunning by thermonarcosis, provide a longer period of permanence in pre rigor mortis, which will result in fillets with a better sensory profile.

Hematological, biochemical, and acid-base response of trotters to submaximal exercise at the end of the horse racing season

Depending on intensity, physical exercise in horses causes various changes in the parameters of hematological, biochemical, acid-base, and electrolyte status, which can affect the health and athletic performance of the horse. This study?s objective was to look at how submaximal exercise at the end of the racing season affected the horses? hematological, biochemical, acid-base, and electrolyte status markers. In this study, eight (n=8) trotters, aged 4?2 years, were involved. Venous blood samples were drawn from each horse by jugular puncture before and after exercise to determine hematologic, biochemical, acid-base and electrolyte parameters. The submaximal physical exercise in this study was two intervals of 2,000 m of slow trotting and two consecutive runs of 500 m at submaximal level. Hematocrit (HCT), red blood cell (RBC) and monocyte count, hemoglobin (HGB) concentration, aspartate aminotransferase (AST) activity, and glucose concentration increased significantly after the exercise. Additionally, significant decreases in venous blood pH, bicarbonate (HCO3-) and total CO2 (TCO2) concentration, base excess of the extracellular fluid (BEecf), and ionized Ca2+ (iCa2+) concentrations were established after exercise. In contrast, partial pressure of CO2 (pCO2), total concentration of weak acids (Atot), the anion gap (AG), and total protein and lactate concentrations were significantly higher after exercise. Considering the significant changes in the parameters of hematological, biochemical, and acid-base status after submaximal exercise, determining those parameters would be useful for monitoring the health and performance of trotters.

Thermodynamic analysis of gate-opening carbon dioxide adsorption behavior of metal-organic frameworks.

Thermodynamic analysis of gate-opening carbon dioxide (CO2) adsorption behavior of metal-organic frameworks (MOFs) was investigated using differential scanning calorimetry (DSC). Unlike measurements under nitrogen atmosphere, obvious exothermic and endothermic peaks were observed in DSC curves under CO2 flow. In situ heating X-ray diffraction and thermogravimetric analyses under CO2 revealed that reversible crystal structure and weight changes occurred upon CO2 adsorption/desorption. The thermodynamic parameters of the CO2 adsorption process by MOFs were determined by DSC analysis at various CO2 partial pressures.

Mechanistic insights into the co-recovery of nickel and iron via integrated carbon mineralization of serpentinized peridotite by harnessing organic ligands.

The rising need to produce a decarbonized supply chain of energy critical metals with inherent carbon mineralization motivates advances in accelerating novel chemical pathways in a mechanistically-informed manner. In this study, the mechanisms underlying co-recovery of energy critical metals and carbon mineralization by harnessing organic ligands are uncovered by investigating the influence of chemical and mineral heterogeneity, along with the morphological transformations of minerals during carbon mineralization. Serpentinized peridotite is selected as the feedstock, and disodium EDTA dihydrate (Na2H2EDTA·2H2O) is used as the organic ligand for metal recovery. Nickel extraction efficiency of ∼80% and carbon mineralization efficiency of ∼73% is achieved at a partial pressure of CO2 of 50 bars, reaction temperature of 185 °C, and 10 hours of reaction time in 2 M NaHCO3 and 0.1 M Na2H2EDTA·2H2O. Extensive magnesite formation is evidence of the carbon mineralization of serpentine and olivine. An in-depth investigation of the chemo-morphological evolution of the CO2-fluid-mineral system during carbon mineralization reveals several critical stages. These stages encompass the initial incongruent dissolution of serpentine resulting in a Si-rich amorphous layer acting as a diffusion barrier for Mg2+ ions, subsequent exfoliation of the silica layer to expose unreacted olivine, and the concurrent formation of magnesite. Organic ligands such as Na2H2EDTA·2H2O aid the dissolution and formation of magnesite crystals. The organic ligand exhibits higher stability for Ni-complex ions than the corresponding divalent metal carbonate. The buffered environment also facilitates concurrent mineral dissolution and carbonate formation. These two factors contribute to the efficient co-recovery of nickel with inherent carbon mineralization to produce magnesium carbonate. These studies provide fundamental insights into the mechanisms underlying the co-recovery of energy critical metals with inherent carbon mineralization which unlocks the value of earth abundant silicate resources for the sustainable recovery of energy critical metals and carbon management.

Carbonate System Seasonal Behavior along a Southeastern Brazilian Estuarine-Lagoon Complex with Different Degrees of Anthropogenic Impacts on its Sectors

This study aimed to understand the behavior of the carbonate system in the Cananéia-Iguape Estuarine-Lagoon Complex (CIELC) to evaluate its potential as a source or sink for atmospheric CO2. This estuarine-lagoon complex is one of the most extensive in Brazil, more than 100 km long and covers protected and sparsely inhabited regions of the state of São Paulo. This system presents, in its southern portion, most preserved areas, and evident anthropogenic impact in the northern portion, where an artificial canal was created in the second half of the 19th century, with the aim of shortening the navigation path link the river to the estuarine system offering a passage to the sea, resulting in several modifications, both from a hydrodynamic and biogeochemical mechanisms. Sampling of salinity (S), temperature (T), total alkalinity (TA), pH, dissolved oxygen (DO), and nutrients (P and Si) were performed along the CIELC in the winter of 2012 and in the summer of 2013. S, TA, pH and nutrients were used to support the understanding the behavior of the species in the carbonate system (CO2 , HCO3 - , CO3 2-) and related variables were used to calculating the partial pressure of CO2 (pCO2 ). The data showed the difference in salinity and carbonate members distinguished the northern and southern areas, the influence of the marine waters entrance by the bars, and the predominance of the system as a source of CO2 , even in the most preserved area. However, the difference in this behavior is most evident under anthropogenic pression offering risk of extreme changes in direction to the southern sector, now observed until the intermediate point of the system. The recommendation is an urgency in monitoring this region to minimizes futures environmental changes, as acidification and the increase as a source of CO2 .

Drivers of Air‐Sea CO2 Flux in the Subantarctic Zone Revealed by Time Series Observations

AbstractThe subantarctic zone is an important region in the Southern Ocean with respect to its influence on air‐sea CO2 exchange and the global ocean carbon cycle. However, understanding of the magnitude and drivers of the flux are still being refined. Using observations from the Southern Ocean Time Series (SOTS) station (∼47°S, 142°E) and auxiliary data, we developed a multiple linear regression model to compute the sea surface partial pressure of CO2 (pCO2) over the past two decades. The mean amplitude of the pCO2 seasonal cycle between 2004 and 2021 was 44 μatm (range 30–54 μatm). Summer minima ranged from 310 to 370 μatm and winter maxima were near equilibrium with the atmosphere. The non‐thermal (i.e., biological processes and mixing) contribution to the seasonal variability in pCO2 was several times larger than the thermal contribution. The SOTS region acted as a net carbon sink at annual time scales, with mean magnitude of 6.0 mmol m−2 d−1. The positive phase of the Southern Annular Mode (SAM) increased ocean carbon uptake primarily through an increase in wind speed at zero time lag. Increased surface pCO2 was correlated with a positive SAM with a lag of 4 months, mainly due to reduced biological uptake and increased mixing. During the autotrophic season, pCO2 was predominantly impacted by primary productivity, whereas water mass movement, inferred by temperature and salinity anomalies, had a larger impact on the heterotrophic season. In general, mesoscale processes such as eddies and frontal movement impact the local biogeochemical features more than the SAM.

A Synthesis of Global Coastal Ocean Greenhouse Gas Fluxes

AbstractThe coastal ocean contributes to regulating atmospheric greenhouse gas concentrations by taking up carbon dioxide (CO2) and releasing nitrous oxide (N2O) and methane (CH4). In this second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2), we quantify global coastal ocean fluxes of CO2, N2O and CH4 using an ensemble of global gap‐filled observation‐based products and ocean biogeochemical models. The global coastal ocean is a net sink of CO2 in both observational products and models, but the magnitude of the median net global coastal uptake is ∼60% larger in models (−0.72 vs. −0.44 PgC year−1, 1998–2018, coastal ocean extending to 300 km offshore or 1,000 m isobath with area of 77 million km2). We attribute most of this model‐product difference to the seasonality in sea surface CO2 partial pressure at mid‐ and high‐latitudes, where models simulate stronger winter CO2 uptake. The coastal ocean CO2 sink has increased in the past decades but the available time‐resolving observation‐based products and models show large discrepancies in the magnitude of this increase. The global coastal ocean is a major source of N2O (+0.70 PgCO2‐e year−1 in observational product and +0.54 PgCO2‐e year−1 in model median) and CH4 (+0.21 PgCO2‐e year−1 in observational product), which offsets a substantial proportion of the coastal CO2 uptake in the net radiative balance (30%–60% in CO2‐equivalents), highlighting the importance of considering the three greenhouse gases when examining the influence of the coastal ocean on climate.

Fyzická aktivita detských pacientov s nešpecifickými črevnými zápalovými ochoreniami – výhody a limitácie

Summary: Introduction: Inflammatory bowel diseases (IBDs) are a group of diseases including Crohn’s disease, ulcerative colitis and unclassified IBD. They are chronic, immune-mediated inflammatory diseases of the gastrointestinal tract. Due to their extraintestinal manifestation, they are considered to be systemic diseases. IBD has a negative impact on health-related quality of life. The treatment is life-long and may be accompanied by side effects. Low-intensity activity of moderate duration is sufficient to elicit improvements in fitness, decrease stress, and improve symptoms. In this study, the relationship between physical activity and IBD development and course is described. Aims: To assess the relationship between physical activity and exercise capacity and the severity and course of IBD. Methods: Probands with IBD and healthy controls underwent pulmonary function testing (PFT) and cardiopulmonary exercise testing (CPET). The results were compared between these two groups; in the IBD group, the results were correlated with disease activity parameters as well. In the IBD group, the probands were encouraged to perform regular physical activity. After 0.5–1 year, they underwent another CPET. Their exercise capacity development was objectively assessed and it was correlated with their IBD development. Results: Forty-one children were included in the study. Twenty of them were healthy controls, while 21 comprised the IBD patient group. These probands underwent the PFT and CPET. When comparing healthy controls and IBD patients, significant differences were found in peak oxygen uptake and peak work rate. In the IBD group, a negative correlation was found between peak work rate and C-reactive protein concentration. In faecal calprotectin, a significant correlation was found only in the subgroup with ulcerative colitis – the negative correlation with peak oxygen uptake and partial pressure of CO2 in exhaled air in the peak of the exercise. PCDAI correlated positively with ventilatory index, peak dead space and tidal volume ratio but negatively with peak work rate, work rate at the time of anaerobic threshold, peak oxygen uptake and oxygen uptake efficacy slope. In PUCAI, we found a positive correlation with CO2 ventilatory uptake at the time of anaerobic threshold and negative correlations with peak oxygen uptake and oxygen uptake efficacy slope. In further CPET in the IBD group, a significant decrease was found in faecal calprotectin and PCDAI or PUCAI; there were also positive correlations between PCDAI/PUCAI changes and resting heart rate changes. The negative correlation was found in the correlation with the changes in peak oxygen uptake, metabolic index and ventilatory equivalent for CO2 at the time of anaerobic threshold. Conclusion: These results suggest that regular recreational physical exercise positively impacts IBD. When adhering to treatment recommendations, doing sport professionally is also possible. Key words: inflammatory bowel diseases – physical activity

Promoted Ni–Co bimetallic catalysts for glycerol dry reforming: Understanding the physiochemical properties and carbon formation

Glycerol dry reforming (GDR) is one of the alternatives for syngas production by utilizing glycerol, a by-product of biodiesel. This current work focusing on the effect of Ce, Ru and Pd as promoters on Ni–Co/Al2O3 catalysts. Ultrasonic-assisted impregnation was utilized to synthesize the catalysts and GDR was carried out by varying the reactant partial pressure CO2 to glycerol ranging from 10 to 40 kPa at 1073 K. Characterization studies showed that incorporation of promoter reduced Ni–Co agglomeration and increased metal dispersion on Al2O3 support. This resulted in smaller crystallite size and more consumption of H2 and CO2 based on H2-TPR and CO2-TPD analyses. Irrespective of reactant partial pressure, the catalytic performance was increased with following trend; Ni–Co/Al2O3 < Ce–Ni–Co/Al2O3 < Ru–Ni–Co/Al2O3 < Pd–Ni–Co/Al2O3. The best reactant partial pressure (CO2 and glycerol) was achieved at 20 kPa and the effect of competing reactant caused a significant decline in catalytic performance beyond 20 kPa. Oxygen storage capacity, basic nature and redox cycle of promoters assisting in the carbon reduction on catalysts surface. Overall, Pd–Ni–Co/Al2O3 recorded the highest catalytic activity and lowest carbon formation (7.25%) compared to other promoted catalysts credited to their smallest crystallite size (7.12 nm), great metal dispersion (77.4%, 2.95), highest H2 production, CO2 consumption and oxygen storage capacity.

Comparative investigation on high-pressure flow accelerated corrosion at gradual contraction and gradual expansion pipes

In current study, the flow accelerated corrosion behaviors of X65 steel gradual contraction and gradual expansion pipes under high-pressure conditions were comparatively investigated by establishing dynamic in situ electrochemical tests under high CO2 partial pressure conditions in a loop apparatus. The findings indicate that the corrosion rate is reduced along the flowing direction of gradual contraction pipe. Nevertheless, the corrosion rate firstly descends and subsequently ascends along the flowing direction of gradual expansion pipe, and the lowest corrosion rate is presented in inclination segment close to the straight pipe with large diameter. The corrosion rate at the top wall of gradual contraction pipe is symmetrical to that at the bottom wall, while it is asymmetrically distributed at the top wall and the bottom wall of inclination segment in gradual expansion pipe. The distribution of corrosion rate is correlated with the flow fields at gradual contraction and gradual expansion pipes. Furthermore, the special corrosion rate distribution at inclination segment of gradual expansion pipe is ascribed to the formation of secondary flow and vortexes.

Investigation of barium iron oxides for CO2 capture and chemical looping oxygen uncoupling

The performance of two underexploited ternary oxides – Ba3Fe2O6 and Ba5Fe2O8 are investigated for carbon dioxide capture and chemical looping oxygen uncoupling. The ternary compound Ba3Fe2O6 was found to have a structure characterised by space group Pa3¯. Experimental results have shown that both Ba3Fe2O6 and Ba5Fe2O8 are capable of cyclically capturing CO2 at temperatures above 800 °C. Ba5Fe2O8 demonstrated superior CO2 capture performance compared to Ba3Fe2O6, with consistent gravimetric CO2 uptake capacities of 4.35 wt% and 13.39 wt% at 900 °C and 1000 °C, respectively, over 20 cycles. In comparison, Ba3Fe2O6 demonstrated high initial CO2 uptake capacities which deteriorated cyclically, with 20 cycle average capacities of 7.73 wt% and 11.99 wt% at 900 °C and 1000 °C, respectively. Ba3Fe2O6 also exhibits excellent recyclability and satisfactory chemical looping oxygen uncoupling (CLOU) activity over temperature swing cycles between 550 °C and 950 °C. In contrast, the strong affinity with CO2 makes Ba5Fe2O8 unsuitable for application in chemical looping oxygen uncoupling or chemical looping air separation, especially in the presence of substantial partial pressures of CO2.