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1.
Transcutaneous carbon dioxide measurements in fruits, vegetables and humans: A prospective observational study.
Sochet, AA, Bessone, SK, Parilla, NW, Nakagawa, TA
European journal of anaesthesiology. 2019;(12):904-910
Abstract
BACKGROUND Transcutaneous carbon dioxide measurement (TcCO2) is frequently used as a surrogate for arterial blood gas sampling in adults and children with critical illness. Data from noninvasive TcCO2 monitoring assists with clinical decisions regarding mechanical ventilation settings, estimation of metabolic consumption and determination of adequate end-organ tissue perfusion. OBJECTIVES To report TcCO2 values obtained from various fruits, vegetables and elite critical care medicine specialists. DESIGN Prospective, observational, nonblinded cohort study. SETTINGS Single-centre, tertiary paediatric referral centre and organic farmers' market. PARTICIPANTS Vegetables and fruits included 10 samples of each of the following: red delicious apple (Malus domestica), manzano banana (Musa sapientum), key lime (Citrus aurantiifolia), miniature sweet bell pepper (Capsicum annuum), sweet potato (Ipomoea batatas) and avocado (Persea americana). Ten human controls were studied including a paediatric intensivist, a paediatric inpatient hospital physician, four paediatric resident physicians and four paediatric critical care nurses. INTERVENTIONS None. MAIN OUTCOME MEASURES TcCO2 values for each species and device response times. RESULTS TcCO2 readings were measurable in all study species except the sweet potato. Mean ± SD values of TcCO2 for human controls [4.34 ± 0.37 kPa (32.6 ± 2.8 mmHg)] were greater than apples [3.09 ± 0.19 kPa (23.2 ± 1.4 mmHg), P < 0.01], bananas [2.73 ± 0.28 kPa (20.5 ± 2.1 mmHg), P < 0.01] and limes [2.76 ± 0.52 kPa (20.7 ± 3.9 mmHg), P < 0.01] but no different to those of avocados [4.29 ± 0.44 kPa (32.2 ± 3.3 mmHg), P = 0.77] and bell peppers [4.19 ± 1.13 kPa (31.4 ± 8.5 mmHg), P = 0.68]. Transcutaneous response times did not differ between research cohorts and human controls. CONCLUSION We found nonroot, nontuberous vegetables to have TcCO2 values similar to that of healthy, human controls. Fruits yield TcCO2 readings, but substantially lower than human controls.
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2.
Characterization of marine bacterial carbonic anhydrase and their CO2 sequestration abilities based on a soil microcosm.
Jaya, P, Nathan, VK, Ammini, P
Preparative biochemistry & biotechnology. 2019;(9):891-899
Abstract
The novel technology of biological carbon sequestration using microbial enzymes have numerous advantages over conventional sequestration strategies. In the present study, extracellular carbonic anhydrase (CA) producing bacteria were isolated from water samples in the Arabian Sea, India. A potential isolate, Bacillus safensis isolate AS-75 was identified based on 16S rDNA sequence analysis. The culture conditions suitable for CA production were 32 °C incubation temperature with 4% NaCl and 10 mM Zn supplementation. Experimental optimization of culture conditions enhanced enzyme activity to 265 U mL-1. CA specific gene was characterized and based on the analysis, the CA of B. safensis isolate AS-75 was a leucine (11.3%) with α-helices as the dominant component in its secondary structure. Based on soil microcosm studies, CA could sequester CO2 by 95.4% ± 0.11% in sterilized soil with enzyme microcosm. Hence, the application of enzyme was found to be more effective in removing CO2.
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3.
Provision of carbon skeleton for lipid synthesis from the breakdown of intracellular protein and soluble sugar in Phaeodactylum tricornutum under high CO2.
Huang, A, Wu, S, Gu, W, Li, Y, Xie, X, Wang, G
BMC biotechnology. 2019;(1):53
Abstract
BACKGROUND Increasing CO2 emissions have resulted in ocean acidification, affecting marine plant photosynthesis and changing the nutrient composition of marine ecosystems. The physiological and biochemical processes of marine phytoplankton in response to ocean acidification have been reported, but have been mainly focused on growth and photosynthetic physiology. To acquire a thorough knowledge of the molecular regulation mechanisms, model species with clear genetic background should be selected for systematic study. Phaeodactylum tricornutum is a pennate diatom with the characteristics of small genome size, short generation cycle, and easy to transform. Furthermore, the genome of P. tricornutum has been completely sequenced. RESULTS AND DISCUSSION In this study, P. tricornutum was cultured at high and normal CO2 concentrations. Cell composition changes during culture time were investigated. The 13C isotope tracing technique was used to determine fractional labeling enrichments for the main cellular components. The results suggested that when lipid content increased significantly under high CO2 conditions, total protein and soluble sugar contents decreased. The 13C labeling experiment indicated that the C skeleton needed for fatty acid C chain elongation in lipid synthesis under high CO2 conditions is not mainly derived from NaHCO3 (carbon fixed by photosynthesis). CONCLUSION This study indicated that breakdown of intracellular protein and soluble sugar provide C skeleton for lipid synthesis under high CO2 concentration.
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4.
CO2 and O2 removal during continuous veno-venous hemofiltration: a pilot study.
Jonckheer, J, Spapen, H, Debain, A, Demol, J, Diltoer, M, Costa, O, Lanckmans, K, Oshima, T, Honoré, PM, Malbrain, M, et al
BMC nephrology. 2019;(1):222
Abstract
BACKGROUND Carbon dioxide (CO2) accumulation is a challenging issue in critically ill patients. CO2 can be eliminated by renal replacement therapy but studies are scarce and clinical relevance is unknown. We prospectively studied CO2 and O2 behavior at different sample points of continuous veno-venous hemofiltration (CVVH) and build a model to calculate CO2 removal bedside. METHODS In 10 patients receiving standard CVVH under citrate anticoagulation, blood gas analysis was performed at different sample points within the CVVH circuit. Citrate was then replaced by NaCl 0.9% and sampling was repeated. Total CO2 (tCO2), CO2 flow (V̇CO2) and O2 flow (V̇O2) were compared between different sample points. The effect of citrate on transmembrane tCO2 was evaluated. Wilcoxon matched-pairs signed rank test was performed to evaluate significance of difference between 2 data sets. Friedman test was used when more data sets were compared. RESULTS V̇CO2 in the effluent (26.0 ml/min) correlated significantly with transmembrane V̇CO2 (24.2 ml/min). This represents 14% of the average expired V̇CO2 in ventilated patients. Only 1.3 ml/min CO2 was removed in the de-aeration chamber, suggesting that CO2 was almost entirely cleared across the membrane filter. tCO2 values in effluent, before, and after the filter were not statistically different. Transmembrane tCO2 under citrate or NaCl 0.9% predilution also did not differ significantly. No changes in V̇O2 were observed throughout the CVVH circuit. Based on recorded data, formulas were constructed that allow bedside evaluation of CVVH-attributable CO2 removal. CONCLUSION A relevant amount of CO2 is removed by CVVH and can be quantified by one simple blood gas analysis within the circuit. Future studies should assess the clinical impact of this observation. TRIAL REGISTRATION The trial was registered at https://clinicaltrials.gov with trial registration number NCT03314363 on October 192,017.
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5.
A whole canopy gas exchange system for the targeted manipulation of grapevine source-sink relations using sub-ambient CO2.
Smith, JP, Edwards, EJ, Walker, AR, Gouot, JC, Barril, C, Holzapfel, BP
BMC plant biology. 2019;(1):535
Abstract
BACKGROUND Elucidating the effect of source-sink relations on berry composition is of interest for wine grape production as it represents a mechanistic link between yield, photosynthetic capacity and wine quality. However, the specific effects of carbohydrate supply on berry composition are difficult to study in isolation as leaf area or crop adjustments can also change fruit exposure, or lead to compensatory growth or photosynthetic responses. A new experimental system was therefore devised to slow berry sugar accumulation without changing canopy structure or yield. This consisted of six transparent 1.2 m3 chambers to enclose large pot-grown grapevines, and large soda-lime filled scrubbers that reduced carbon dioxide (CO2) concentration of day-time supply air by approximately 200 ppm below ambient. RESULTS In the first full scale test of the system, the chambers were installed on mature Shiraz grapevines for 14 days from the onset of berry sugar accumulation. Three chambers were run at sub-ambient CO2 for 10 days before returning to ambient. Canopy gas exchange, and juice hexose concentrations were determined. Net CO2 exchange was reduced from 65.2 to 30 g vine- 1 day- 1, or 54%, by the sub-ambient treatment. At the end of the 10 day period, total sugar concentration was reduced from 95 to 77 g L- 1 from an average starting value of 23 g L- 1, representing a 25% reduction. Scaling to a per vine basis, it was estimated that 223 g of berry sugars accumulated under ambient supply compared to 166 g under sub-ambient, an amount equivalent to 50 and 72% of total C assimilated. CONCLUSIONS Through supply of sub-ambient CO2 using whole canopy gas exchange chambers system, an effective method was developed for reducing photosynthesis and slowing the rate of berry sugar accumulation without modifying yield or leaf area. While in this case developed for further investigations of grape and wine composition, the system has broader applications for the manipulation and of study of grapevine source-sink relations.
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6.
A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System.
Hou, W, Wang, H, Wang, W, Liu, Z, Li, Q
Journal of visualized experiments : JoVE. 2019;(148)
Abstract
Injecting carbon dioxide (CO2) into a deep coal seam is of great significance for reducing the concentration of greenhouse gases in the atmosphere and increasing the recovery of coalbed methane. A visualized and constant-volume gas-solid coupling system is introduced here to investigate the influence of CO2 sorption on the physical and mechanical properties of coal. Being able to keep a constant volume and monitor the sample using a camera, this system offers the potential to improve instrument accuracy and analyze fracture evolution with a fractal geometry method. This paper provides all steps to perform a uniaxial compression experiment with a briquette sample in different CO2 pressures with the gas-solid coupling test system. A briquette, cold-pressed by raw coal and sodium humate cement, is loaded in high-pressure CO2, and its surface is monitored in real-time using a camera. However, the similarity between the briquette and the raw coal still needs improvement, and a flammable gas such as methane (CH4) cannot be injected for the test. The results show that CO2 sorption leads to peak strength and elastic modulus reduction of the briquette, and the fracture evolution of the briquette in a failure state indicates fractal characteristics. The strength, elastic modulus, and fractal dimension are all correlated with CO2 pressure but not with a linear correlation. The visualized and constant-volume gas-solid coupling test system can serve as a platform for experimental research about rock mechanics considering the multifield coupling effect.
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7.
The molecular evolution of C4 photosynthesis: opportunities for understanding and improving the world's most productive plants.
Niklaus, M, Kelly, S
Journal of experimental botany. 2019;(3):795-804
Abstract
C4 photosynthesis is a convergent evolutionary trait that enhances photosynthetic efficiency in a variety of environmental conditions. It has evolved repeatedly following a fall in atmospheric CO2 concentration such that there is up to a 30 million year difference in the amount of time that natural selection has had to improve C4 function between the oldest and youngest C4 lineages. This large difference in time, coupled with the phylogenetic distance between lineages, has resulted in a large disparity in anatomy, physiology, and biochemistry between extant C4 species. This review summarizes the myriad of molecular sequence changes that have been linked to the evolution of C4 photosynthesis. These range from single nucleotide changes to duplication of entire genes, and provide a roadmap for how natural selection has adapted enzymes and pathways for enhanced C4 function. Finally, this review discusses how this molecular diversity can provide opportunities for understanding and improving photosynthesis for multiple important C4 food, feed, and bioenergy crops.
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8.
Carbon Dioxide As a Standard of Care for Zero Contrast Interventions: When, Why and How?
Bisdas, T, Koutsias, S
Current pharmaceutical design. 2019;(44):4662-4666
Abstract
BACKGROUND Traditional contrast media containing iodine remain the gold standard for vessel visualization during endovascular procedures. On the other hand, their use has several side effects and implications and may cause contrast medium-induced nephropathy. Carbon dioxide (CO2) angiography is an old alternative technique used only for critical patients in order to prevent kidney damages or allergic reactions. Zero contrast procedure: The availability of automated CO2 injectors has led to an increase in the use of CO2 angiography, providing an option for zero contrast interventions, preserving patient renal function and saving costs for the hospital facility. Taking advantage of the properties of CO2 gas, it is possible to improve the performance of some complex procedures such as atherectomy and the detection of type II endoleaks after EVARs. However, a learning curve is needed to get good imaging, and learn about the qualities and limitations of the technique. CONCLUSIONS The use of automatic delivery systems for CO2 angiography appears to be a good choice for the use of CO2 as the first imaging option. The standardization of injection protocols and the extensive use of this technique could lead to significant benefits both for the patient's prospects and health facilities.
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9.
Changes in size and composition of pigweed (Amaranthus hybridus L.) calcium oxalate crystals under CO2 starvation conditions.
Tooulakou, G, Nikolopoulos, D, Dotsika, E, Orkoula, MG, Kontoyannis, CG, Liakopoulos, G, Klapa, MI, Karabourniotis, G
Physiologia plantarum. 2019;(3):862-872
Abstract
The functional role(s) of plant calcium oxalate (CaOx) crystals are still poorly understood. Recently, it was shown that crystals function as dynamic carbon pools whose decomposition could provide CO2 to photosynthesis when stomata are closed (e.g. under drought conditions) and CO2 starvation conditions may be created within the mesophyll. This biochemical process, named as 'alarm photosynthesis', can become crucial for plant survival under adverse conditions. Here, we study crystal decomposition under controlled CO2 starvation conditions (either in the shoot or in the root) to obtain a better insight into the process of crystal formation and function. Hydroponically grown pigweed plants were kept in CO2 -free air and/or CO2 -free nutrient medium for 9 days. Crystal volume was monitored daily, and carbon stable isotope composition (δ13 C) and Fourier transformation Raman spectra were obtained at the end of the experiment. A considerable reduction in the leaf crystal volume was observed in shoot-CO2 -starved plants at the end of the experiment. The smallest crystals were isolated from the plants in which carbon was excluded from both the shoot and the root and contained potassium nitrate. Crystal δ13 C of CO2 -starved plants was altered in a predicted way. Specifically, it depended on the average calculated isotope fractionation of all carbon fixation processes considered to be contributing in each experimental treatment. The results of the present study confirmed the correlation between CO2 starvation conditions and the CaOx crystal decomposition. Inorganic carbon fixed in the root may represent a major carbon source for CaOx formation.
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10.
Biological CO2 mitigation by microalgae: technological trends, future prospects and challenges.
de Morais, MG, de Morais, EG, Duarte, JH, Deamici, KM, Mitchell, BG, Costa, JAV
World journal of microbiology & biotechnology. 2019;(5):78
Abstract
The increase in the CO2 concentration in the Earth's atmosphere has been a topic of worldwide concern since anthropogenic emissions of greenhouse gases began increasing considerably during the industrial period. The effects of these mass emissions are probably the main cause of global warming, which has been observed over recent decades. Among the various techniques of CO2 capture, microalgal biofixation by photosynthesis is considered a promising technology due to the efficiency of these microorganisms in converting this gas into organic compounds through its use as a nutrient in the culture medium. Over the years, several research centers have developed studies on this subject, which have focused on mainly the development of bioreactors, the growth conditions that increase the efficiency of the process and the production of biomass with applicability in several areas. The biological mitigation of CO2 by microalgae has many advantages, including reductions in the concentration of an industrially sourced greenhouse gas and the energy or food obtained from the produced photosynthetic biomass. This versatility allows for the cultivation of economically useful biomass while reducing the environmental impacts of industrial facilities. In this context, this mini-review aims to discuss new technologies and strategies along with the main challenges and future prospects in the field and the ecological and economic impacts of CO2 biofixation by microalgae.