23,528 results match your criteria gas transport


A Molecular Simulation Study of Silica/Polysulfone Mixed Matrix Membrane for Mixed Gas Separation.

Polymers (Basel) 2021 Jul 1;13(13). Epub 2021 Jul 1.

Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.

Polysulfone-based mixed matrix membranes (MMMs) incorporated with silica nanoparticles are a new generation material under ongoing research and development for gas separation. However, the attributes of a better-performing MMM cannot be precisely studied under experimental conditions. Thus, it requires an atomistic scale study to elucidate the separation performance of silica/polysulfone MMMs. Read More

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Evaporation kinetics of a polydisperse ensemble of drops.

Philos Trans A Math Phys Eng Sci 2021 Sep 19;379(2205):20200309. Epub 2021 Jul 19.

Department of Theoretical and Mathematical Physics, Laboratory of Multi-Scale Mathematical Modeling, Ural Federal University, Ekaterinburg, 620000, Russian Federation.

A mathematical model of the evaporation of a polydisperse ensemble of drops, with allowance for a nonlinear 'diffusion' term in the kinetic equation for the population density distribution function, is developed. The model describes the interaction of a gas phase with vaporizing drops: it has great potential for application in condensed matter physics, thermophysics and engineering devices (e.g. Read More

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September 2021

Personalized mechanical ventilation in acute respiratory distress syndrome.

Crit Care 2021 07 16;25(1):250. Epub 2021 Jul 16.

Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.

A personalized mechanical ventilation approach for patients with adult respiratory distress syndrome (ARDS) based on lung physiology and morphology, ARDS etiology, lung imaging, and biological phenotypes may improve ventilation practice and outcome. However, additional research is warranted before personalized mechanical ventilation strategies can be applied at the bedside. Ventilatory parameters should be titrated based on close monitoring of targeted physiologic variables and individualized goals. Read More

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Collective energy-spectrum broadening of a proton beam in a gas-discharge plasma.

Phys Rev E 2021 Jun;103(6-1):063216

Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.

An accurate understanding of ion-beam transport in plasmas is crucial for applications in inertial fusion energy and high-energy-density physics. We present an experimental measurement on the energy spectrum of a proton beam at 270 keV propagating through a gas-discharge hydrogen plasma. We observe the energies of the beam protons changing as a function of the plasma density and spectrum broadening due to a collective beam-plasma interaction. Read More

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Polycyclic aromatic hydrocarbons in marine mammals: A review and synthesis.

Mar Pollut Bull 2021 Jul 13;171:112699. Epub 2021 Jul 13.

Instituto Oceanográfico da Universidade de São Paulo (IO-USP), Praça do Oceanográfico, 191, Cidade Universitária, São Paulo 05508-120, Brazil.

Most marine mammal species and populations are listed as endangered, threatened, or depleted under the Endangered Species Act and the Marine Mammal Protection Act. Organic contaminants such as polycyclic aromatic hydrocarbons from anthropogenic activities are part of the threat to marine mammals. The evaluation of the potential bioaccumulation of these compounds by marine mammals is a tool for adoption of policies to reduce polycyclic aromatic hydrocarbons discharges to the marine environment, where important players such as the oil and gas industries, maritime transport and sewage companies operate. Read More

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Evaluating Indoor Air Chemical Diversity, Indoor-to-Outdoor Emissions, and Surface Reservoirs Using High-Resolution Mass Spectrometry.

Environ Sci Technol 2021 Aug 16;55(15):10255-10267. Epub 2021 Jul 16.

Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States.

Detailed offline speciation of gas- and particle-phase organic compounds was conducted using gas/liquid chromatography with traditional and high-resolution mass spectrometers in a hybrid targeted/nontargeted analysis. Observations were focused on an unoccupied home and were compared to two other indoor sites. Observed gas-phase organic compounds span the volatile to semivolatile range, while functionalized organic aerosols extend from intermediate volatility to ultra-low volatility, including a mix of oxygen, nitrogen, and sulfur-containing species. Read More

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Numerical modeling as a tool for evaluating the renewability of geothermal resources: the case study of the Euganean Geothermal System (NE Italy).

Environ Geochem Health 2021 Jul 16. Epub 2021 Jul 16.

Department of Geosciences, Università degli Studi di Padova, Padova, Italy.

Renewable natural resources are strategic for reducing greenhouse gas emissions and the human footprint. The renewability of these resources is a crucial aspect that should be evaluated in utilization of scenario planning. The renewability of geothermal resources is strictly related to the physical and geological processes that favor water circulation and heating. Read More

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Empirical determination of explosive vapor transport efficiencies.

Analyst 2021 Jul 16. Epub 2021 Jul 16.

Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, D.C. 20375, USA.

The transport efficiency of 2,4-dinitrotoluene (2,4-DNT), 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazinane (RDX) trace vapors through tubing materials that commonly constitute vapor handling infrastructures have been determined for a variety of tubing dimensions and sampling conditions. Using a programmable temperature vaporization inlet coupled with a gas chromatography mass spectrometer (PTV-GC-MS), the explosive vapors were quantified both with and without a length of tubing of a specific material in the sampling flow path. At vapor temperatures of 30 °C and 66 °C, minimal attenuations were observed for 2,4-DNT and TNT vapor concentrations when the tubing material was in-line with the sampling flow path, indicating that the transport is largely unaffected by interactions with the surface of the tubing materials. Read More

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The Significance of Enabling Human Consideration in Policymaking: How to Get the E-Ferry That You Want.

Front Psychol 2021 29;12:635722. Epub 2021 Jun 29.

Department of Logistics Management, Izmir University of Economics, Izmir, Turkey.

There is broad agreement in literature and policy that the transport sector needs to maximise electric mobility, in order to lower both energy consumption and greenhouse gas emissions. This ongoing transformation continues to require a high degree of technological innovation. Consequently, policymakers are striving to reward innovation in procurement tender contracts, in order to achieve sustainable innovation. Read More

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Structural and functional characterization of the intracellular filament-forming nitrite oxidoreductase multiprotein complex.

Nat Microbiol 2021 Jul 15. Epub 2021 Jul 15.

Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany.

Nitrate is an abundant nutrient and electron acceptor throughout Earth's biosphere. Virtually all nitrate in nature is produced by the oxidation of nitrite by the nitrite oxidoreductase (NXR) multiprotein complex. NXR is a crucial enzyme in the global biological nitrogen cycle, and is found in nitrite-oxidizing bacteria (including comammox organisms), which generate the bulk of the nitrate in the environment, and in anaerobic ammonium-oxidizing (anammox) bacteria which produce half of the dinitrogen gas in our atmosphere. Read More

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Longitudinal changes in compliance, oxygenation and ventilatory ratio in COVID-19 versus non-COVID-19 pulmonary acute respiratory distress syndrome.

Crit Care 2021 07 15;25(1):248. Epub 2021 Jul 15.

Medical ICU, University Hospital of Strasbourg, University of Strasbourg, Strasbourg, France.

Background: Differences in physiology of ARDS have been described between COVID-19 and non-COVID-19 patients. This study aimed to compare initial values and longitudinal changes in respiratory system compliance (C), oxygenation parameters and ventilatory ratio (VR) in patients with COVID-19 and non-COVID-19 pulmonary ARDS matched on oxygenation.

Methods: 135 patients with COVID-19 ARDS from two centers were included in a physiological study; 767 non-COVID-19 ARDS from a clinical trial were used for the purpose of at least 1:2 matching. Read More

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Saturated fatty acids accelerate linear motility through mitochondrial ATP production in bull sperm.

Reprod Med Biol 2021 Jul 6;20(3):289-298. Epub 2021 May 6.

Laboratory of Reproductive Endocrinology Graduate School of Biosphere Science Hiroshima University Hiroshima Japan.

Purpose: The present study was undertaken to clarify whether bovine sperm could take up fatty acids (FAs) and produce ATP to maintain linear motility.

Methods: Frozen bovine semen was thawed in media containing either lipid mixture (LM) or FAs, and sperm motility was analyzed. The kinetic changes in FA levels in sperm were detected using gas chromatography-mass spectrometry. Read More

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Integration of aprotic CO reduction to oxalate at a Pb catalyst into a GDE flow cell configuration.

Faraday Discuss 2021 07;230(0):360-374

Institute of Chemical Technology, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.

Electrochemical CO2 reduction to oxalic acid in aprotic solvents could be a potential pathway to produce carbon-neutral oxalic acid. One of the challenges in aprotic CO2 reduction are the limited achievable current densities under standard conditions, despite the increased CO2 solubility compared to aqueous applications. The application of aprotic solvents can reduce CO2 rather selectively to oxalate, and faradaic efficiencies (FEs) of up to 80% were achieved in this study with a Pb catalyst in acetonitrile, the FE being mainly dictated by the local CO2 concentration at the electrode. Read More

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Electrochemical carbon dioxide reduction in ionic liquids at high pressure.

Faraday Discuss 2021 Jul;230(0):331-343

Department of Chemistry, University of Liverpool, Liverpool, UK. and Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool, UK.

Imidazolium ionic liquids are potentially useful solvents for both carbon dioxide reduction conversion and capture. In particular electrocatalytic CO2 reduction has been shown to occur at low overpotentials using a 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf]) and water mixed solvent. A limitation of such solvent systems is their viscosity, making it hard to maintain reasonable catalytic current densities without energy intensive stirring/agitation of the electrolyte. Read More

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Epitaxial Molybdenum Disulfide/Gallium Nitride Junctions: Low-Knee-Voltage Schottky-Diode Behavior at Optimized Interfaces.

ACS Appl Mater Interfaces 2021 Jul 14;13(29):35105-35112. Epub 2021 Jul 14.

Department of Chemistry and Materials Science & Engineering Program, University of California-Riverside, Riverside, California 92521, United States.

Low turn-on (knee) voltage (∼0.3 V) Schottky-diode behavior of a four-layer (4L) MoS/GaN junction is achieved by optimizing the in situ interface preparation of the GaN substrate prior to MoS overlayer growth in a vacuum system using metallic molybdenum and hydrogen sulfide gas as precursors. The process leads to a clean nitrogen-terminated GaN surface that bonds well to the MoS film revealing a 2 × 2 reconstruction at the interface observed in low-energy electron diffraction (LEED). Read More

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Fluid Dynamics of Respiratory Infectious Diseases.

Authors:
Lydia Bourouiba

Annu Rev Biomed Eng 2021 07;23:547-577

The Fluid Dynamics of Disease Transmission Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; email:

The host-to-host transmission of respiratory infectious diseases is fundamentally enabled by the interaction of pathogens with a variety of fluids (gas or liquid) that shape pathogen encapsulation and emission, transport and persistence in the environment, and new host invasion and infection. Deciphering the mechanisms and fluid properties that govern and promote these steps of pathogen transmission will enable better risk assessment and infection control strategies, and may reveal previously underappreciated ways in which the pathogens might actually adapt to or manipulate the physical and chemical characteristics of these carrier fluids to benefit their own transmission. In this article, I review our current understanding of the mechanisms shaping the fluid dynamics of respiratory infectious diseases. Read More

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Carbonaceous aerosols in urban Chongqing, China: Seasonal variation, source apportionment, and long-range transport.

Chemosphere 2021 Jul 8;285:131462. Epub 2021 Jul 8.

Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China.

Seventy-seven PM2.5 samples were collected at an urban site (Chongqing University Campus A) in October 2015 (autumn), December 2015 (winter), March 2016 (spring), and August 2016 (summer). These samples were analysed for organic carbon (OC), elemental carbon (EC), and their associated char, soot, 16 PAHs, and 28 n-alkanes to trace sources, and atmospheric transport pathways. Read More

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Synthesis and Characterization of Ligand-Linked Pt Nanoparticles: Tunable, Three-Dimensional, Porous Networks for Catalytic Hydrogen Sensing.

ChemistryOpen 2021 Jul;10(7):697-712

Institute of Applied and Physical Chemistry, University of Bremen, Leobener Str. 6, 28359, Bremen, Germany.

Porous networks of Pt nanoparticles interlinked by bifunctional organic ligands have shown high potential as catalysts in micro-machined hydrogen gas sensors. By varying the ligand among p-phenylenediamine, benzidine, 4,4''-diamino-p-terphenyl, 1,5-diaminonaphthalene, and trans-1,4-diaminocyclohexane, new variants of such networks were synthesized. Inter-particle distances within the networks, determined via transmission electron microscopy tomography, varied from 0. Read More

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Physiological and Proteomic Responses to Drought in Leaves of () Yü et Lu.

Front Plant Sci 2021 24;12:620499. Epub 2021 Jun 24.

State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin, China.

Various environmental stresses strongly influence plant development. Among these stresses is drought, which is a serious threat that can reduce agricultural productivity and obstruct plant growth. Although the mechanism of plants in response to drought has been studied extensively, the adaptive strategies of () Yü et Lu grown in drought and rewatered habitats remain undefined. Read More

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A large fixed bed reactor for MRI operando experiments at elevated temperature and pressure.

Rev Sci Instrum 2021 Apr;92(4):043711

Chemical Process Engineering (CVT), Faculty of Production Engineering (FB 4), University of Bremen, Leobener Straße 6, 28359 Bremen, Germany.

Recently, in situ studies using nuclear magnetic resonance (NMR) have shown the possibility to monitor local transport phenomena of gas-phase reactions inside opaque structures. Their application to heterogeneously catalyzed reactions remains challenging due to inherent temperature and pressure constraints. In this work, an NMR-compatible reactor was designed, manufactured, and tested, which can endure high temperatures and increased pressure. Read More

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Microplastics in the western Pacific and South China Sea: Spatial variations reveal the impact of Kuroshio intrusion.

Environ Pollut 2021 Jul 6;288:117745. Epub 2021 Jul 6.

State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China; Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, 361102, China; College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China; Coastal and Ocean Management Institute, Xiamen University, Xiamen, 361102, China. Electronic address:

Surface currents play an essential role in the worldwide distribution of microplastics in the coastal seas and open oceans. As a branch of the western boundary currents (WBCs), Kuroshio changes seawater properties and pollutant levels of the South China Sea (SCS) during its intrusion process. To study the impact of Kuroshio intrusion on microplastics, we conducted field observations on surface water from the western Pacific (WP) and SCS. Read More

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Particle/gas partitioning for semi-volatile organic compounds (SVOCs) in Level III multimedia fugacity models: Gaseous emissions.

Sci Total Environ 2021 Jul 1;795:148729. Epub 2021 Jul 1.

Institute of Ocean Sciences, Department of Fisheries and Oceans, P.O. Box 6000, Sidney, BC V8L 4B2, Canada; Centre for Earth Observation Science, University of Manitoba, Winnipeg R3T 2N2, Canada.

Atmospheric transport is a global-scale process that moves semi-volatile organic compounds (SVOCs) rapidly from source regions to remote locations, where these chemicals have never been produced or used. Particle/gas (P/G) partitioning of SVOCs during atmospheric transport governs wet and dry deposition, and thereby controls the efficiency and scope of long-range atmospheric transport and fate for these sorts of compounds. Previous work has shown that the assumption of steady state between particulate and gaseous phases in the atmosphere leads to model results that more closely match observations especially for compounds that strongly favor the particulate phase. Read More

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Rapid screening of nanopore candidates in nanoporous single-layer graphene for selective separations using molecular visualization and interatomic potentials.

J Chem Phys 2021 May;154(18):184111

Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

Nanoporous single-layer graphene is promising as an ideal membrane because of its extreme thinness, chemical resistance, and mechanical strength, provided that selective nanopores are successfully incorporated. However, screening and understanding the transport characteristics of the large number of possible pores in graphene are limited by the high computational requirements of molecular dynamics (MD) simulations and the difficulty in experimentally characterizing pores of known structures. MD simulations cannot readily simulate the large number of pores that are encountered in actual membranes to predict transport, and given the huge variety of possible pores, it is hard to narrow down which pores to simulate. Read More

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Covalent Organic-Inorganic Hybrid Superlattice Covered with Organic Functional Group for Highly Sensitive and Selective Gas Sensing.

Angew Chem Int Ed Engl 2021 Jul 9. Epub 2021 Jul 9.

Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155 Yangqiao Road West, 350002, Fuzhou, CHINA.

Organic-inorganic hybrid superlattices (OIHSLs) hold attractive physical and chemical properties, while the construction of single-crystal covalent OIHSLs has not been achieved. Herein a coordination assembly strategy was proposed to create a single-crystal covalent OIHSL PbBDT (BDT=1,4-benzenedithiolate), where layered [PbS 2 ] sublattice covalently connects with benzene sublattice. The covalent bonding offers better thermo-/chemi-stability, inter-sublattice electron transport, and unique organic-group-functionalized surface, which may enable better performances in chemical applications than non-covalent OIHSL. Read More

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Oxygen-Selective Diffusion-Bubbling Membranes with Core-Shell Structure: Bubble Dynamics and Unsteady Effects.

Langmuir 2021 Jul 8;37(28):8370-8381. Epub 2021 Jul 8.

Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, 49 Leninsky Prospekt, Moscow 119334, Russian Federation.

Oxygen is the second-largest-volume industrial gas that is mainly produced using cryogenic air separation. However, the state-of-the-art cryogenic technology thermodynamic efficiency has approached a theoretical limit as near as is practicable. Therefore, there is stimulus to develop an alternative technology for efficient oxygen separation from air. Read More

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Changing atmospheric acidity as a modulator of nutrient deposition and ocean biogeochemistry.

Sci Adv 2021 Jul 7;7(28). Epub 2021 Jul 7.

Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden.

Anthropogenic emissions to the atmosphere have increased the flux of nutrients, especially nitrogen, to the ocean, but they have also altered the acidity of aerosol, cloud water, and precipitation over much of the marine atmosphere. For nitrogen, acidity-driven changes in chemical speciation result in altered partitioning between the gas and particulate phases that subsequently affect long-range transport. Other important nutrients, notably iron and phosphorus, are affected, because their soluble fractions increase upon exposure to acidic environments during atmospheric transport. Read More

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Dynamic Crossover in Fluids: From Hard Spheres to Molecules.

J Phys Chem Lett 2021 Jul 7;12(27):6411-6417. Epub 2021 Jul 7.

Université de Pau et des Pays de l'Adour, e2s UPPA, TOTAL, CNRS, LFCR, UMR 5150, Laboratoire des fluides complexes et leurs reservoirs, Pau 64000, France.

We propose a simple and generic definition of a demarcation reconciling structural and dynamic frameworks when combined with the entropy scaling framework. This crossover line between gas- and liquid-like behaviors is defined as the curve for which an individual property, the contribution to viscosity due to molecules' translation, is exactly equal to a collective property, the contribution to viscosity due to molecular interactions. Such a definition is shown to be consistent with the one based on the minima of the kinematic viscosity. Read More

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Including leaf trait information helps empirical estimation of jmax from vcmax in cool-temperate deciduous forests.

Plant Physiol Biochem 2021 Jun 30;166:839-848. Epub 2021 Jun 30.

Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.

Understanding the uncertainty in the parameterization of the two photosynthetic capacity parameters, leaf maximum carboxylation rate (Vcmax), and maximum electron transport rate (Jmax), is crucial for modeling and predicting carbon fluxes in terrestrial ecosystems. In gas exchange models, to date, Jmax is typically estimated from Vcmax based on a linear regression. However, recent studies have revealed that this relationship varies, dependent upon species, leaf groups, and time, so it is doubtful that the regression applies universally. Read More

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Using a hybrid approach to apportion potential source locations contributing to excess cancer risk of PM-bound PAHs during heating and non-heating periods in a megacity in the Middle East.

Environ Res 2021 Jul 3;201:111617. Epub 2021 Jul 3.

Dipartimento di Scienze Ambientali Informatica e Statistica, Università Ca' Foscari Venezia, Venezia, Italy.

Polycyclic aromatic hydrocarbons (PAHs) represent one of the major toxic pollutants associated with PM with significant human health and climate effects. Because of local and long-range transport of atmospheric PAHs to receptor sites, higher global attentions have been focused to improve PAHs pollution emission management. In this study, PM samples were collected at three urban sites located in the capital of Iran, Tehran, during the heating and non-heating periods (H-period and NH-period). Read More

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New insights into the allosteric effects of CO2 and bicarbonate on crocodilian hemoglobin.

J Exp Biol 2021 Jul 2. Epub 2021 Jul 2.

Department of Biology, Aarhus University, 8000 Aarhus C, Denmark.

Crocodilians are unique among vertebrates in that their hemoglobin (Hb) O2 binding is allosterically regulated by bicarbonate, which forms in the red blood cell upon hydration of CO2. Although known for decades, this remarkable mode of allosteric control has not yet been experimentally verified with direct evidence of bicarbonate binding to crocodilian Hb, probably because of confounding CO2-mediated effects. Here we provide the first quantitative analysis of the separate allosteric effects of CO2 and bicarbonate on purified Hb of the spectacled caiman (Caiman crocodilus). Read More

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