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1
Wu, Yuewei, Jian Wu, Xiaolong Wei, et al. "Theoretical Investigation of C4F7N–CO2 Mixture Decomposition Characteristics Under Extreme Conditions." Energies 18, no. 3 (2025): 591. https://doi.org/10.3390/en18030591.
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Due to their low greenhouse effect and exceptional insulating properties, C4F7N-CO2 gas mixtures have garnered significant attention. In particular, understanding the decomposition characteristics of C4F7N-CO2 is crucial for their practical use as an eco-friendly dielectric medium. At elevated temperatures, the pyrolysis of C4F7N produces high concentrations of CFN, CF3, and C2F2, along with lower levels of C3F5, C4F6N, C2F, and CN. A further increase in temperature may lead to the decomposition of CO2 into CO and additional components such as C2, C2F3, C3F4, C4F7 and C3F6, CF, CO, C3F7, C3F2, C3F, C3F3, C3F3N, C3, CF2, and CF2N. Under electrical discharge conditions, the decomposition of CO2 becomes more pronounced, forming products like CO, C2O, O2, C2O2, and C2O4, with up to 25 decomposition components observed. These include products originated from both C4F7N and CO2 and their combinations. In ultra-high electric field intensities, only small molecules such as O2, C2, C3, and N2 are detected among the decomposition products. This study aims to provide theoretical insights and valuable data to advance research into the decomposition behavior and practical engineering applications of C4F7N-CO2 gas mixtures under extreme conditions.
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Hamed, Raghad Ali, Sabreen Shaker Mahmood, and Ban Dawood Salih. "Synthesis and Applications of Polymer Chelating Resins Containing Schiff Base." Asian Journal of Chemistry 31, no. 9 (2019): 2111–15. http://dx.doi.org/10.14233/ajchem.2019.21794.
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In this article, a series of Schiff-base compounds is prepared by consending aromatic dialdehydes and diamines in the presence of p-toluenesulfonic acid as catalyst. The prepared Schiff bases are characterized by CHNS/O, NMR and FTIR techniques. Moreover, analytical applications of Schiff bases as chelating agent was evaluated by loading (20 %) of compounds (B and C) the urethanic foams. Furthermore, chelating resins type P1 (B) and P2 (C) are also prepared by loading the Schiff base into polymer backbones. Moreover, the batch process is used to study the ability of these resins in recovering metals ions, such as (Mg2+, Pb2+, Cu2+, Cr3+, Ni2+, Co2+, Cd2+ and Ca2+). The study is performed by considering the contact time and pH value. Finally, the polymer’s maximum loading capacity is in the following sequence: P1 (B) Co2+ > Cr3+ > Mg2+ > Ni2+ > Cd2+ > Ca2+ > Pb2+ > Cu2+; P2 (C) Mg2+ > Cd2+ > Ca2+ > Co2+ > Pb2+ > Cu2+ > Cr3+.
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Drenchev, Nikola L., Boris L. Shivachev, Lubomir D. Dimitrov, and Konstantin I. Hadjiivanov. "Effect of Water on CO2 Adsorption on CaNaY Zeolite: Formation of Ca2+(H2O)(CO2), Ca2+(H2O)(CO2)2 and Ca2+(H2O)2(CO2) Complexes." Nanomaterials 13, no. 16 (2023): 2278. http://dx.doi.org/10.3390/nano13162278.
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Efficient CO2 capture materials must possess a high adsorption capacity, suitable CO2 adsorption enthalpy and resistance to water vapor. We have recently reported that Ca2+ cations exchanged in FAU zeolite can attach up to three CO2 molecules. Here we report the effect of water on the adsorption of CO2. Formation of Ca2+(H2O)(CO2), Ca2+(H2O)(CO2)2 and Ca2+(H2O)2(CO2) mixed ligand complexes were established. The Ca2+(H2O)(CO2) species are readily formed even at ambient temperature and are characterized by ν(12CO2) and ν(13CO2) infrared bands at 2358 and 2293 cm−1, respectively. The Ca2+(H2O)(CO2)2 species are produced at low temperature and are identified by a ν(13CO2) band at 2291 cm−1. In the presence of large amounts of water, Ca2+(H2O)2(CO2) complexes were also evidenced by ν(12CO2) and ν(13CO2) bands at 2348 and 2283 cm−1, respectively. The results demonstrate that, although it has a negative effect on CO2 adsorption uptake, water in moderate amounts does not block CO2 adsorption sites.
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PGoh, P., and IG White. "Control of Ram Sperm Adenylate Cyclase by Divalent Cations." Australian Journal of Biological Sciences 41, no. 3 (1988): 377. http://dx.doi.org/10.1071/bi9880377.
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The adenylate cyclase activity of ram sperm increased on freeze-thawing and the enzyme was stable at O�C. Its activity was stimulated by Mn2+, Zn2+, Co2+, Mg2+ and Ca2+ in descending order of activity. The enzyme was insensitive to fluoride when Mn2+ concentration was in excess. Mn2+_ stimulated enzyme activity was decreased by the simultaneous addition of Co2+, or Cd2+, or Ni2+, and particularly Cu2+. Sulfhydryl compounds (viz. dithiothreitol, glutathione, dithiocarbamate, 2- mercaptoethanol, ergothioneine and cysteine) and chelating agents (viz. D-penicillamine and 8-hydroxyquinoline) were effective, to varying degrees, in overcoming the inhibition by Cu2+. Ca2+ augmented the stimulatory effect of Mg2+, Co2+, Zn2+ and Mn2+ on enzyme activity.
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Makrlík, E., J. Budka, P. Vaňura, and P. Selucký. "Solvent extraction of Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ and Ni2+ into nitrobenzene using strontium dicarbollylcobaltate and tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate." Journal of the Serbian Chemical Society 73, no. 12 (2008): 1181–86. http://dx.doi.org/10.2298/jsc0812181m.
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The exchange extraction constants corresponding to the general equilibrium M2+(aq) + SrL2+(nb) ? ?ML2+(nb) + Sr2+(aq) occurring in the two- -phase water-nitrobenzene system (M2+ = Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+ , Mn2+, Co2+ or Ni2+; L = tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate; aq = aqueous phase; nb = nitrobenzene phase) were evaluated from extraction experiments and ?-activity measurements. Furthermore, the stability constants of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Ba2+ < Mn2+ < Pb2+, Co2+ < Cu2+, Zn2+ < Cd2+, Ni2+ < UO22+ < Ca2+.
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Handlogten, Mary E., Naoki Shiraishi, Hisataka Awata, Chunfa Huang, and R. Tyler Miller. "Extracellular Ca2+-sensing receptor is a promiscuous divalent cation sensor that responds to lead." American Journal of Physiology-Renal Physiology 279, no. 6 (2000): F1083—F1091. http://dx.doi.org/10.1152/ajprenal.2000.279.6.f1083.
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The extracellular Ca2+-sensing receptor (CaR) responds to polycations, including Ca2+ and neomycin. This receptor is a physiological regulator of systemic Ca2+ metabolism and may also mediate the toxic effects of hypercalcemia. A number of divalent cations, including Pb2+, Co2+, Cd2+, and Fe2+, are toxic to the kidney, brain, and other tissues where the CaR is expressed. To determine which divalent cations can activate the CaR, we expressed the human CaR in HEK-293 cells and measured activation of phospholipase A2(PLA2) and the mitogen-activated protein kinase p42ERK in response to potential agonists for the receptor. HEK-293 cells expressing the nonfunctional mutant CaR R796W served as controls. Extracellular Ca2+, Ba2+, Cd2+, Co2+, Fe2+, Gd3+, Ni2+, Pb2+, and neomycin activated the CaR, but Hg2+and Fe3+ did not. We analyzed the kinetics of activation of p42ERK and PLA2 by the CaR in response to Ca2+, Co2+, and Pb2+. The EC50 values ranged from ∼0.1 mM for Pb2+ to ∼4.0 mM for Ca2+. The Hill coefficients were >3, indicating multiple cooperative ligand binding sites or subunits. Submaximal concentrations of Ca2+ and Pb2+ were additive for activation of the CaR. The EC50 for Ca2+ or Pb2+ was reduced four- to fivefold by the presence of the other ion. These divalent cations also activated PLA2 via the CaR in Madin-Darby canine kidney cells that stably express the CaR. We conclude that many divalent cations activate the CaR and that their effects are additive. The facts that the CaR is a promiscuous polycation sensor and that the effects of these ions are additive to activate it suggest that the CaR may contribute to the toxicity of some heavy metals such as Pb2+, Cd2+, Co2+, and Fe2+ for the kidney and other tissues where it is expressed.
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Wellner-Kienitz, M. C., H. Shams, and P. Scheid. "Contribution of Ca2+-Activated K+ Channels to Central Chemosensitivity in Cultivated Neurons of Fetal Rat Medulla." Journal of Neurophysiology 79, no. 6 (1998): 2885–94. http://dx.doi.org/10.1152/jn.1998.79.6.2885.
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Wellner-Kienitz, M.-C., H. Shams, and P. Scheid. Contribution of Ca2+-activated K+ channels to central chemosensitivity in cultivated neurons of fetal rat medulla. J. Neurophysiol. 79: 2885–2894, 1998. Neurons in fetal rat medullary slices that exhibited spontaneous electrical activity after blockade of synaptic transmission were investigated for their response to decreases in extracellular pH. Increases in [H+] (induced either by fixed acid or increases in PCO2) induced a significant increase in the frequency of action potentials, associated with a membrane depolarization, and/or increases in the slope of the interspike depolarization. In addition, CO2/H+ prolonged the repolarizing phase of action potentials and reduced the afterhyperpolarization, suggesting that K+ channels were the primary site of CO2/H+ action. The type of K+ channel that was modulated by CO2/H+ was identified by application of agents that inhibited Ca2+-activated K+ channels either directly (tetraethylammonium chloride, TEA) or indirectly (Cd2+ ions) by inhibiting Ca2+ influx. CO2/H+ effects on neuronal activity were abolished after application of these blockers. The contribution of Ca2+-activated K+ channels to H+ sensitivity of these neurons was confirmed further in voltage-clamp experiments in which outward rectifying I-V curves were recorded that revealed a zero current potential of −70 mV. CO2/H+ induced a prominent reduction in outward currents and shifted the zero current potential to more positive membrane potentials (mean −63 mV). The CO2/H+-sensitive current reversed at −72 mV and was blocked by external application of TEA. It is concluded that CO2/H+ exerts its stimulatory effects on fetal medullary neurons by inhibition of Ca2+-activated K+ channels, either directly or indirectly, by blocking voltage-dependent Ca2+ channels, which in turn results in a reduction of K+ efflux and in cell depolarization.
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Oberhauser, A., O. Alvarez, and R. Latorre. "Activation by divalent cations of a Ca2+-activated K+ channel from skeletal muscle membrane." Journal of General Physiology 92, no. 1 (1988): 67–86. http://dx.doi.org/10.1085/jgp.92.1.67.
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Several divalent cations were studied as agonists of a Ca2+-activated K+ channel obtained from rat muscle membranes and incorporated into planar lipid bilayers. The effect of these agonists on single-channel currents was tested in the absence and in the presence of Ca2+. Among the divalent cations that activate the channel, Ca2+ is the most effective, followed by Cd2+, Sr2+, Mn2+, Fe2+, and Co2+. Mg2+, Ni2+, Ba2+, Cu2+, Zn2+, Hg2+, and Sn2+ are ineffective. The voltage dependence of channel activation is the same for all the divalent cations. The time-averaged probability of the open state is a sigmoidal function of the divalent cation concentration. The sigmoidal curves are described by a dissociation constant K and a Hill coefficient N. The values of these parameters, measured at 80 mV are: N = 2.1, K = 4 X 10(-7) mMN for Ca2+; N = 3.0, K = 0.02 mMN for Cd2+; N = 1.45, K = 0.63 mMN for Sr2+; N = 1.7, K = 0.94 mMN for Mn2+; N = 1.1, K = 3.0 mMN for Fe2+; and N = 1.1 K = 4.35 mMN for Co2+. In the presence of Ca2+, the divalent cations Cd2+, Co2+, Mn2+, Ni2+, and Mg2+ are able to increase the apparent affinity of the channel for Ca2+ and they increase the Hill coefficient in a concentration-dependent fashion. These divalent cations are only effective when added to the cytoplasmic side of the channel. We suggest that these divalent cations can bind to the channel, unmasking new Ca2+ sites.
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Wang, Jiaen, Tianliang Song, Huaxiang Chen, et al. "Bioinspired High-Strength Montmorillonite-Alginate Hybrid Film: The Effect of Different Divalent Metal Cation Crosslinking." Polymers 14, no. 12 (2022): 2433. http://dx.doi.org/10.3390/polym14122433.
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The natural nacre has a regular ordered layered structure of calcium carbonate tablets and ion crosslinking proteins stacked alternately, showing outstanding mechanical properties. Inspired by nacre, we fabricated different divalent metal cation-crosslinked montmorillonite-alginate hybrid films (MMT-ALG-X2+; X2+ = Cu2+, Cd2+, Ba2+, Ca2+, Ni2+, Co2+ or Mn2+). The effect of ionic crosslinking strength and hydrogen bond interaction on the mechanical properties of the nacre-mimetics was studied. With the cations affinities with ALG being increased (Mn2+ < Co2+ = Ni2+ < Ca2+ < Ba2+ < Cd2+ < Cu2+), the tensile strength of nacre-mimetics showed two opposite influence trends: Weak ionic crosslinking (Mn2+, Co2+, Ni2+ and Ca2+) can synergize with hydrogen bonds to greatly increase the tensile properties of the sample; Strong ionic crosslinking (Ba2+, Cd2+, Cu2+) and hydrogen bonding form a competitive relationship, resulting in a rapid decrease in mechanical properties. Mn2+ crosslinking generates optimal strength of 288.0 ± 15.2 MPa with an ultimate strain of 5.35 ± 0.6%, obviously superior to natural nacre (135 MPa and 2%). These excellent mechanical properties arise from the optimum synergy of ion crosslinking and interfacial hydrogen bonds between crosslinked ALG and MMT nanosheets. In addition, these metal ion-crosslinked composite films show different colors, high visible transparency, and excellent UV shielding properties.
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Rani, Poonam, Kashmiri Lal, and Rahul Shrivastava. "Tris-Triazole Based Chemosensors for Selective Sensing of Pb2+ Ions." Asian Journal of Chemistry 31, no. 11 (2019): 2443–47. http://dx.doi.org/10.14233/ajchem.2019.22076.
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A series of novel tris-trizole based neutral chemosensors (4a-c) have been synthesized via click reaction and characterized by various spectral techniques. All the synthesized triazoles were evaluated for their ion binding properties towards various cations (Cu2+, Zn2+, Ca2+, Co2+, Cd2+, Hg2+, Pb2+ and Ni2+) by UV-visible titration experiments. It was observed that the addition of Pb2+ ions to compound 4a led to significant changes in UV-visible spectrum and a new UV band was observed at 262 nm. Further, the Job′s plot confirmed the formation of 1:1 complex between compound 4a and Pb2+. The synthesized chemosensor selectively sense Pb2+ ions in preference to other cations like Cu2+, Zn2+, Ca2+, Co2+, Cd2+, Hg2+, Pb2+ and Ni2+.
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Wen, Xin Rong, and Chang Qing Tu. "Study on Determination of Trace Cobalt in Environmental Water Samples after Separation/Enrichment Using Microcrystalline Phenolphthalein Modified with 8-Hydroxyquinoline." Applied Mechanics and Materials 316-317 (April 2013): 279–85. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.279.
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The paper presents a novel method for the separation/enrichment of trace Co2+ using microcrystalline phenolphthalein modified with 8-hydroxyquinoline (HQ) prior to the determination by spectrophotometry. The effects of different parameters,such as the dosages of phenolphthalein and HQ,various salts and acidity on the enrichment yield of Co2+ have been investigated to select the experimental conditions. The possible enrichment mechanism of Co2+ was discussed.The results showed that under the optimum conditions, Co2+ could be quantificationally adsorbed on the surface of microcrystalline phenolphthalein in the form of the chelate precipitate of Co(HQ)2 ,while K+,Na+,Ca2+,Mg2+,Cd2+,Zn2+,Mn2+,Fe2+ and Al3+ could not be adsorbed at all.Therefore,Co2+ was completely separated from the above metal ions in the solution. A new method for the spectrophotometric determination of trace cobalt after separation/enrichment using microcrystalline phenolphthalein modified with 8-hydroxyquinoline was established.The proposed method has been successfully applied to the determination of Co2+ in various environmental water samples, and the results agreed well with those obtained by FAAS method.
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Elferink, J. G., and M. Deierkauf. "Suppressive action of cobalt on exocytosis and respiratory burst in neutrophils." American Journal of Physiology-Cell Physiology 257, no. 5 (1989): C859—C864. http://dx.doi.org/10.1152/ajpcell.1989.257.5.c859.
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Activation of exocytosis and respiratory burst in rabbit neutrophils by the chemotactic peptide fMet-Leu-Phe is inhibited by Co2+. Inhibition is antagonized by extracellular Ca2+ and is dependent on the time of preincubation of cells with Co2+ before addition of activator. Co2+ inhibits the enhancement of 45Ca association that occurs during activation with fMet-Leu-Phe. Interference with Ca2+ translocation across the plasma membrane by Co2+ is probably not the cause of inhibition of neutrophil activation, because activation in the absence of extracellular Ca2+ is inhibited by Co2+. Activation of neutrophils by phorbol myristate acetate is inhibited at higher Co2+ concentrations than activation by fMet-Leu-Phe. Inhibition of the superoxide production by Co2+ occurs both in the presence or in the absence of cytochalasin B. Fluorescence of neutrophils loaded with quin2 is diminished by Co2+, indicating that Co2+ had entered into the cytoplasm. The results are compatible with the view that Co2+ inhibits exocytosis and respiratory burst in neutrophils by an interaction with a Ca2+-dependent intracellular target.
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Petkova, Petya. "THE COMPLEXES OF Co2+ IN Bi12SiO20 AND Co3+ IN Bi12TiO20." Journal scientific and applied research 3, no. 1 (2013): 78–83. http://dx.doi.org/10.46687/jsar.v3i1.67.
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We have investigated the absorption of the Co doped Bi12MO20 (M = Si, Ti) in the spectral region 12 092–18 149 cm-1. The observed absorption band is due to the Co-impurity in the visible spectral region. This absorption band does not contain information about the exact energy position of the Co levels. Therefore, we have calculated the second derivative of absorption. It is established that Co2+ ions are surrounded by distorted tetrahedral coordination in Bi12SiO20 (BSO). The energy level structure of the Co2+ ion in BSO and this of Co3+ ion in Bi12TiO20 are also presented. We have calculated the crystal field parameter Dq and the Racah parameters B and C for Co2+ ion.
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Monteilh-Zoller, Mahealani K., Meredith C. Hermosura, Monica J. S. Nadler, Andrew M. Scharenberg, Reinhold Penner, and Andrea Fleig. "TRPM7 Provides an Ion Channel Mechanism for Cellular Entry of Trace Metal Ions." Journal of General Physiology 121, no. 1 (2002): 49–60. http://dx.doi.org/10.1085/jgp.20028740.
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Trace metal ions such as Zn2+, Fe2+, Cu2+, Mn2+, and Co2+ are required cofactors for many essential cellular enzymes, yet little is known about the mechanisms through which they enter into cells. We have shown previously that the widely expressed ion channel TRPM7 (LTRPC7, ChaK1, TRP-PLIK) functions as a Ca2+- and Mg2+-permeable cation channel, whose activity is regulated by intracellular Mg2+ and Mg2+·ATP and have designated native TRPM7-mediated currents as magnesium-nucleotide–regulated metal ion currents (MagNuM). Here we report that heterologously overexpressed TRPM7 in HEK-293 cells conducts a range of essential and toxic divalent metal ions with strong preference for Zn2+ and Ni2+, which both permeate TRPM7 up to four times better than Ca2+. Similarly, native MagNuM currents are also able to support Zn2+ entry. Furthermore, TRPM7 allows other essential metals such as Mn2+ and Co2+ to permeate, and permits significant entry of nonphysiologic or toxic metals such as Cd2+, Ba2+, and Sr2+. Equimolar replacement studies substituting 10 mM Ca2+ with the respective divalent ions reveal a unique permeation profile for TRPM7 with a permeability sequence of Zn2+ ≈ Ni2+ &gt;&gt; Ba2+ &gt; Co2+ &gt; Mg2+ ≥ Mn2+ ≥ Sr2+ ≥ Cd2+ ≥ Ca2+, while trivalent ions such as La3+ and Gd3+ are not measurably permeable. With the exception of Mg2+, which exerts strong negative feedback from the intracellular side of the pore, this sequence is faithfully maintained when isotonic solutions of these divalent cations are used. Fura-2 quenching experiments with Mn2+, Co2+, or Ni2+ suggest that these can be transported by TRPM7 in the presence of physiological levels of Ca2+ and Mg2+, suggesting that TRPM7 represents a novel ion-channel mechanism for cellular metal ion entry into vertebrate cells.
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Regmi, Chhabilal, Saeed Ashtiani, Zdeněk Sofer, et al. "CeO2-Blended Cellulose Triacetate Mixed-Matrix Membranes for Selective CO2 Separation." Membranes 11, no. 8 (2021): 632. http://dx.doi.org/10.3390/membranes11080632.
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Due to the high affinity of ceria (CeO2) towards carbon dioxide (CO2) and the high thermal and mechanical properties of cellulose triacetate (CTA) polymer, mixed-matrix CTA-CeO2 membranes were fabricated. A facile solution-casting method was used for the fabrication process. CeO2 nanoparticles at concentrations of 0.32, 0.64 and 0.9 wt.% were incorporated into the CTA matrix. The physico-chemical properties of the membranes were evaluated by SEM-EDS, XRD, FTIR, TGA, DSC and strain-stress analysis. Gas sorption and permeation affinity were evaluated using different single gases. The CTA-CeO2 (0.64) membrane matrix showed a high affinity towards CO2 sorption. Almost complete saturation of CeO2 nanoparticles with CO2 was observed, even at low pressure. Embedding CeO2 nanoparticles led to increased gas permeability compared to pristine CTA. The highest gas permeabilities were achieved with 0.64 wt.%, with a threefold increase in CO2 permeability as compared to pristine CTA membranes. Unwanted aggregation of the filler nanoparticles was observed at a 0.9 wt.% concentration of CeO2 and was reflected in decreased gas permeability compared to lower filler loadings with homogenous filler distributions. The determined gas selectivity was in the order CO2/CH4 > CO2/N2 > O2/N2 > H2/CO2 and suggests the potential of CTA-CeO2 membranes for CO2 separation in flue/biogas applications.
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Lange, Diana Dostal, and Randolph M. Beaudry. "EFFECTS OF 2% 02, 50% CO2, AND THE COMBINATION ON FLAVOR QUALITY AND FERMENTATION PRODUCTS OF STRAWBERRIES AND BLUEBERRIES." HortScience 27, no. 6 (1992): 677e—677. http://dx.doi.org/10.21273/hortsci.27.6.677e.
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Low O2 and high CO2 concentrations can be used effectively to slow respiration and retard decay, but anaerobic and C02-injurious conditions must be avoided. The objective of this research was to: 1) determine the effects of low O2 and very high-C02 on flavor quality and accumulation of fermentation products. Strawberries and blueberries were stored in 2% O2/0% CO2, 20% 02/50% CO2, 2% O2/50% CO2, and 20% 02/0% CO2 for 0, 2, 4, 6, and 8 days at 20C. A taste panel evaluated the berries at the end of each storage period and again after 2 days under ambient conditions. Ethanol was the primary fermentation product that accumulated in response to low O2 and high CO2 concentrations. However, acetaldehyde was produced preferentially in response to elevated C02 levels. The flavor quality of the strawberries and blueberries was only acceptable for 2 days for treatments containing 50% CO2. The most intense off-flavors were detected in the 2% 02/50% CO2 and 20% O2/50% CO2 samples. 50% CO2 was highly effective in preventing decay, but this concentration was too high for acceptable flavor quality for storage periods greater than 2 days.
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Fenk, Lorenz A., and Mario de Bono. "Environmental CO2 inhibits Caenorhabditis elegans egg-laying by modulating olfactory neurons and evokes widespread changes in neural activity." Proceedings of the National Academy of Sciences 112, no. 27 (2015): E3525—E3534. http://dx.doi.org/10.1073/pnas.1423808112.
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Carbon dioxide (CO2) gradients are ubiquitous and provide animals with information about their environment, such as the potential presence of prey or predators. The nematode Caenorhabditis elegans avoids elevated CO2, and previous work identified three neuron pairs called “BAG,” “AFD,” and “ASE” that respond to CO2 stimuli. Using in vivo Ca2+ imaging and behavioral analysis, we show that C. elegans can detect CO2 independently of these sensory pathways. Many of the C. elegans sensory neurons we examined, including the AWC olfactory neurons, the ASJ and ASK gustatory neurons, and the ASH and ADL nociceptors, respond to a rise in CO2 with a rise in Ca2+. In contrast, glial sheath cells harboring the sensory endings of C. elegans’ major chemosensory neurons exhibit strong and sustained decreases in Ca2+ in response to high CO2. Some of these CO2 responses appear to be cell intrinsic. Worms therefore may couple detection of CO2 to that of other cues at the earliest stages of sensory processing. We show that C. elegans persistently suppresses oviposition at high CO2. Hermaphrodite-specific neurons (HSNs), the executive neurons driving egg-laying, are tonically inhibited when CO2 is elevated. CO2 modulates the egg-laying system partly through the AWC olfactory neurons: High CO2 tonically activates AWC by a cGMP-dependent mechanism, and AWC output inhibits the HSNs. Our work shows that CO2 is a more complex sensory cue for C. elegans than previously thought, both in terms of behavior and neural circuitry.
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Pilling, S., G. A. Carvalho, H. A. de Abreu, B. R. L. Galvão, C. H. da Silveira, and M. S. Mateus. "Understanding the Molecular Kinetics and Chemical Equilibrium Phase of Frozen CO during Bombardment by Cosmic Rays by Employing the PROCODA Code." Astrophysical Journal 952, no. 1 (2023): 17. http://dx.doi.org/10.3847/1538-4357/acdb4a.
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Abstract Within the cold regions of space, ices that are enriched with carbon monoxide (CO) molecules are exposed to ionizing radiation, which triggers new reactions and desorption processes. Laboratory studies on astrochemical ices employing different projectiles have revealed the appearance of several new species. In this study, we employed the upgraded PROCODA code, which involves a calculation phase utilizing thermochemistry data, to map the chemical evolution of pure CO ice irradiated by cosmic-ray analogs. In the model, we have considered 18 different chemical species (six observed: CO, CO2, C3, O3, C2O, and C5O3; 12 unobserved: C, O, C2, O2, CO3, C3O, C4O, C5O, C2O2, C2O3, C3O2, and C4O2) coupled at 156 reaction routes. Our best-fit model provides effective reaction rates (effective rate constants, (ERCs)), branching ratios for reactions within reaction groups, several desorption parameters, and the characterization of molecular abundances at the chemical equilibrium (CE) phase. The most abundant species within the ice at the CE phase were atomic oxygen (68.2%) and atomic carbon (18.2%), followed by CO (11.8%) and CO2 (1.6%). The averaged modeled desorption yield and rate were 1.3e5 molecules ion−1 and 7.4e13 molecules s−1, respectively, while the average value of ERCs in the radiation-induced dissociation reactions was 2.4e-1 s−1 and for the bimolecular reactions it was 4.4e-24 cm3 molecule−1 s−1. We believe that the current kinetics study can be used in future astrochemical models to better understand the chemical evolution of embedded species within astrophysical ices under the presence of an ionizing radiation field.
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Cheng, Kai, Songjian Zhao, Jiazheng Ren, Haoran Li, and Yongsheng Chen. "CO2 Self-Poisoning and Its Mitigation in CuO Catalyzed CO Oxidation: Determining and Speeding up the Rate-Determining Step." Catalysts 11, no. 6 (2021): 654. http://dx.doi.org/10.3390/catal11060654.
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Cu-based catalysts are promising for CO oxidation applications with catalyst deactivation being a major barrier. We start with a CuO/Al2O3 catalyst and find that while the CO conversion decreases, CO2 accumulates and the average Cu chemical state stays the same. It suggests CO2 self-poisoning, i.e., CO2 desorption is the rate-determining step. Subsequently, experiments are performed to prove this hypothesis by showing (1) CO2 adsorption inhibits O2 adsorption, (2) complete desorption of CO2 regenerate the catalyst, (3) pre-adsorbed CO2 quenches catalyst activity which recovers during the reaction and (4) the apparent activation energy is consistent with CO2 desorption. It is further evidenced by using a stronger CO2 adsorbing support CeO2 to speed up CO2 desorption from the CuO sites resulting in a superior CuO/CeO2 catalyst. It provides an example for experimentally deciding and speeding up the rate-determining step in a catalytic reaction.
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Callens, M., P. Tomme, H. Kersters-Hilderson, R. Cornelis, W. Vangrysperre, and C. K. De Bruyne. "Metal ion binding to d-xylose isomerase from Streptomyces violaceoruber." Biochemical Journal 250, no. 1 (1988): 285–90. http://dx.doi.org/10.1042/bj2500285.
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The binding of two activating cations, Co2+ and Mg2+, and of one inhibitory cation, Ca2+, to D-xylose isomerase from Streptomyces violaceoruber was investigated. Equilibrium-dialysis and spectrometric studies revealed that the enzyme binds 2 mol of Co2+/mol of monomer. Difference absorption spectrometry in the u.v. and visible regions indicated that the environment of the first Co2+ ion is markedly different from that of the second Co2+ ion. The first Co2+ appears to have a six-co-ordinate. The conformational change induced by binding of Co2+ to the first site is maximum after the addition of 1 equivalent of Co2+ and yields a binding constant greater than or equal to 3.3 × 10(6) M-1. Binding of Co2+ to the second, weaker-binding, site caused a visible difference spectrum. The association constant estimated from Co2+ titrations at 585 nm agrees satisfactorily with the value of 4 × 10(4) M-1 obtained from equilibrium dialysis. Similarly, the enzyme undergoes a conformational change on binding of Mg2+ or Ca2+, the binding constants being estimated as 1 × 10(5) M-1 and 5 × 10(5) M-1 respectively. Competition between the activating Mg2+ and Co2+ and the inhibitory Ca2+ ion for both sites was further evidenced by equilibrium dialysis and by spectral displacement studies.
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Golubev, O. V., P. S. Il'chuk, A. A. Sadovnikov, and A. L. Maksimov. "Carbon Dioxide Utilization Using Plasma Reactor Packed with Magnesia-Ceria Catalysts with Various Morphology." Нефтехимия 63, no. 5 (2023): 720–34. http://dx.doi.org/10.31857/s0028242123050106.
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A series of CeO2–MgO catalysts with different molar ratio was prepared for the plasma-activated CO2 decomposition to CO and O2. The catalysts were synthesized by the sol-gel method and characterized by physicochemical methods (XRD, SEM, XPS, low-temperature N2 adsorption, CO2-TPD). The highest CO2 conversion (31%) was achieved in the presence of the catalyst with the highest CeO2 content. The addition of H2 into a CO2 decomposition system was also studied. No CO2 methanation occurred in the presence of synthesized catalysts, though an increase in the CO2-to-CO conversion was observed due to an increase of a discharge power in the presence of molecular hydrogen.
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Segal, M., and J. L. Barker. "Rat hippocampal neurons in culture: Ca2+ and Ca2+-dependent K+ conductances." Journal of Neurophysiology 55, no. 4 (1986): 751–66. http://dx.doi.org/10.1152/jn.1986.55.4.751.
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Rat hippocampal neurons grown in dissociated cell culture were studied in a medium containing 1 microM tetrodotoxin (TTX) and 25 mM tetraethylammonium (TEA), which eliminated the Na+ and K+ conductances normally activated by depolarizing current injections. In this medium depolarizing current pulses evoked depolarizing regenerative potentials and afterhyperpolarizations in most cells. Both of these events were blocked by close application of Co2+ or Cd2+. These events resemble Ca2+ spikes reported previously in hippocampal pyramidal cells. The membrane potential at which these Ca2+ spikes could be triggered and the rheobase current necessary were dependent on the potential at which the cell was conditioned: the more depolarized the holding potential, the more negative the absolute potential at which a spike could be triggered and the less rheobase current required. The duration of these Ca2+ spikes was also sensitive to the holding potential: the more depolarized the holding level, the longer the duration of the triggered spikes. The amplitude and duration of the Ca2+ spikes were enhanced in a reversible manner by 0.5-1.0 mM 4-aminopyridine (4-AP) delivered in the vicinity of the cell. Two-electrode voltage-clamp analysis of cells studied in TTX, TEA-containing medium revealed an inward current response that peaked in 25-50 ms during depolarizing commands. This response first became detectable during commands to -30 mV. It peaked in amplitude during commands to -10 mV and was enhanced in medium containing elevated [Ca2+]0. It was blocked by either 20 mM Mg2+, 0.2 mM Cd2+, 5 mM Co2+, or 5 mM Mn2+. These results have led us to identify this inward current response as ICa2+. 4-AP enhanced the magnitude and duration of ICa2+ independent of the drug's depressant effects on a transient K+ current also observed under these same experimental conditions. In many but not all cells the Ca2+ spike was followed by a long-lasting hyperpolarization associated with an increase in membrane conductance. This was blocked by Co2+. Under voltage clamp ICa2+ was followed by a slowly developing outward current response that was attenuated by Co2+ or Cd2+. These properties observed under current- and voltage-clamp recording conditions are superficially similar to those previously reported for Ca2+-dependent K+ conductance mechanisms (IC) recorded in these and other membranes. Long-lasting tail currents following activation of IC inverted in the membrane potential range for the K+ equilibrium potential found in these cells.
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Han, Jinlong, and Minmin Luo. "Loss of CO2 sensing by the olfactory system of CNGA3 knockout mice." Current Zoology 56, no. 6 (2010): 793–99. http://dx.doi.org/10.1093/czoolo/56.6.793.
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Abstract Atmospheric CO2 can signal the presence of food, predators or environmental stress and trigger stereotypical behaviors in both vertebrates and invertebrates. Recent studies have shown that the necklace olfactory system in mice sensitively detects CO2 in the air. Olfactory CO2 neurons are believed to rely on cyclic guanosine monophosphate (cGMP) as the key second messenger; however, the specific ion channel underlying CO2 responses remains unclear. Here we show that CO2-evoked neuronal and behavioral responses require cyclic nucleotide-gated (CNG) channels consisting of the CNGA3 subunit. Through Ca2+-imaging, we found that CO2-triggered Ca2+ influx was abolished in necklace olfactory sensory neurons (OSNs) of CNGA3-knockout mice. Olfactory detection tests using a Go/No-go paradigm showed that these knockout mice failed to detect 0.5% CO2. Thus, sensitive detection of atmospheric CO2 depends on the function of CNG channels consisting of the CNGA3 subunit in necklace OSNs. These data support the important role of the necklace olfactory system in CO2 sensing and extend our understanding of the signal transduction pathway mediating CO2 detection in mammals.
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Konsolakis, Michalis, Maria Lykaki, Sofia Stefa, et al. "CO2 Hydrogenation over Nanoceria-Supported Transition Metal Catalysts: Role of Ceria Morphology (Nanorods versus Nanocubes) and Active Phase Nature (Co versus Cu)." Nanomaterials 9, no. 12 (2019): 1739. http://dx.doi.org/10.3390/nano9121739.
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In this work we report on the combined impact of active phase nature (M: Co or Cu) and ceria nanoparticles support morphology (nanorods (NR) or nanocubes (NC)) on the physicochemical characteristics and CO2 hydrogenation performance of M/CeO2 composites at atmospheric pressure. It was found that CO2 conversion followed the order: Co/CeO2 > Cu/CeO2 > CeO2, independently of the support morphology. Co/CeO2 catalysts demonstrated the highest CO2 conversion (92% at 450 °C), accompanied by 93% CH4 selectivity. On the other hand, Cu/CeO2 samples were very selective for CO production, exhibiting 52% CO2 conversion and 95% CO selectivity at 380 °C. The results obtained in a wide range of H2:CO2 ratios (1–9) and temperatures (200–500 °C) are reaching in both cases the corresponding thermodynamic equilibrium conversions, revealing the superiority of Co- and Cu-based samples in methanation and reverse water-gas shift (rWGS) reactions, respectively. Moreover, samples supported on ceria nanocubes exhibited higher specific activity (µmol CO2·m−2·s−1) compared to samples of rod-like shape, disclosing the significant role of support morphology, besides that of metal nature (Co or Cu). Results are interpreted on the basis of different textural and redox properties of as-prepared samples in conjunction to the different impact of metal entity (Co or Cu) on CO2 hydrogenation process.
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Wang, Lianyong, Takashi Yamano, Shunsuke Takane, et al. "Chloroplast-mediated regulation of CO2-concentrating mechanism by Ca2+-binding protein CAS in the green alga Chlamydomonas reinhardtii." Proceedings of the National Academy of Sciences 113, no. 44 (2016): 12586–91. http://dx.doi.org/10.1073/pnas.1606519113.
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Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a CO2-concentrating mechanism (CCM) to maintain photosynthetic activity in CO2-limiting conditions by sensing environmental CO2 and light availability. Previously, a novel high-CO2–requiring mutant, H82, defective in the induction of the CCM, was isolated. A homolog of calcium (Ca2+)-binding protein CAS, originally found in Arabidopsis thaliana, was disrupted in H82 cells. Although Arabidopsis CAS is reported to be associated with stomatal closure or immune responses via a chloroplast-mediated retrograde signal, the relationship between a Ca2+ signal and the CCM associated with the function of CAS in an aquatic environment is still unclear. In this study, the introduction of an intact CAS gene into H82 cells restored photosynthetic affinity for inorganic carbon, and RNA-seq analyses revealed that CAS could function in maintaining the expression levels of nuclear-encoded CO2-limiting–inducible genes, including the HCO3– transporters high-light activated 3 (HLA3) and low-CO2–inducible gene A (LCIA). CAS changed its localization from dispersed across the thylakoid membrane in high-CO2 conditions or in the dark to being associated with tubule-like structures in the pyrenoid in CO2-limiting conditions, along with a significant increase of the fluorescent signals of the Ca2+ indicator in the pyrenoid. Chlamydomonas CAS had Ca2+-binding activity, and the perturbation of intracellular Ca2+ homeostasis by a Ca2+-chelator or calmodulin antagonist impaired the accumulation of HLA3 and LCIA. These results suggest that Chlamydomonas CAS is a Ca2+-mediated regulator of CCM-related genes via a retrograde signal from the pyrenoid in the chloroplast to the nucleus.
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Park, Eun-Young, and Jungho Choi. "The Performance of Low-Pressure Seawater as a CO2 Solvent in Underwater Air-Independent Propulsion Systems." Journal of Marine Science and Engineering 8, no. 1 (2020): 22. http://dx.doi.org/10.3390/jmse8010022.
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Air-independent propulsion systems have improved the performance and decreased the vulnerability of underwater weapon systems. Reforming systems, however, generates large amounts of water and CO2. The recovery or separation of CO2, a residual gas component generated in vessels, entails considerable cost and energy consumption. It is necessary to understand the characteristics of the interaction between CO2 and seawater under the conditions experienced by underwater weapon systems to design and optimize a CO2 treatment process for dissolving CO2 in seawater. In this study, numerical analysis was conducted using the derived experimental concentration and MATLAB. The diffusion coefficient was derived as a function of temperature according to the CO2 dissolution time. Experiments on CO2 dissolution in seawater were conducted. The concentration of CO2 according to the reaction pressure and experimental temperature was obtained. The diffusion coefficient between CO2 and seawater was found to be 6.3 × 10−5 cm2/s at 25 °C and 7.24 × 10−5 cm2/s at 32 °C. CO2 concentration could be estimated accurately under vessel operating conditions using the derived CO2 diffusion coefficients. Optimal design of the residual gas treatment process will be possible using the derived seawater–CO2 diffusion coefficients under the actual operating conditions experienced by underwater weapon systems.
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Giovannini, I., C. Chiarla, G. Boldrini, and M. Castagneto. "Calculation of venoarterial CO2 concentration difference." Journal of Applied Physiology 74, no. 2 (1993): 959–64. http://dx.doi.org/10.1152/jappl.1993.74.2.959.
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Quantitative relationships in CO2 transport and exchange processes were combined for use as the basic components of an original mathematical model for the calculation of venoarterial blood CO2 concentration difference (v-aDCO2). This is calculated as the sum of the increment in CO2 concentration (CCO2) related to the increase in CO2 tension (delta P) from arterial to venous value at constant O2 saturation (delta CCO2/delta P) and of the increment in CO2 concentration related to the decrease in O2 saturation (delta S) from arterial to venous value at constant CO2 tension (delta CCO2/delta S). The newly developed relationships correlated well with the experimental data from which they were derived (r2 = 0.94–0.99). The results provided by the model compared remarkably well with the results of previously published measurements (r2 = 0.96–0.99). This new model allows one to overcome some of the limitations implicit in previously available methods and provides a useful tool for the assessment and monitoring of hemodynamic, metabolic, and O2-CO2 exchange patterns in whole body and regional vascular beds.
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Wang, Zhi-Qiang, Hui-Hui Liu, Xin-Ping Wu, Peijun Hu, and Xue-Qing Gong. "Hydride Generation on the Cu-Doped CeO2(111) Surface and Its Role in CO2 Hydrogenation Reactions." Catalysts 12, no. 9 (2022): 963. http://dx.doi.org/10.3390/catal12090963.
Full textAbstract:
Ceria-based catalysts exhibit great activity in catalyzing selective hydrogenation of CO2 to methanol. However, the underlying mechanism of this reaction, especially the generation of active H species, remains unclear. In this work, we performed extensive density functional theory calculations corrected by on-site Coulomb interaction (DFT + U) to investigate the H2 dissociation and the reaction between the active H species and CO2 on the pristine and Cu-doped CeO2(111) (denoted as Cu/CeO2(111)) surfaces. Our calculations evidenced that the heterolytic H2 dissociation for hydride generation can more readily occur on the Cu/CeO2(111) surface than on the pristine CeO2(111) surface. We also found that the Cu dopant can facilitate the formation of surface oxygen vacancies, further promoting the generation of hydride species. Moreover, the adsorption of CO2 and the hydrogenation of CO2 to HCOO* can be greatly promoted on the Cu/CeO2(111) surface with hydride species, which can lead to the high activity and selectivity toward CO2 hydrogenation to methanol.
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Cui, Leyu, Kun Ma, Ahmed A. Abdala, et al. "Adsorption of a Switchable Cationic Surfactant on Natural Carbonate Minerals." SPE Journal 20, no. 01 (2014): 70–78. http://dx.doi.org/10.2118/169040-pa.
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Summary A switchable cationic surfactant (e.g., tertiary amine surfactant Ethomeen C12) was previously described as a surfactant that one can inject in high-pressure carbon dioxide (CO2) for foam-mobility control. C12 can dissolve in high-pressure CO2 as a nonionic surfactant and equilibrate with brine as a cationic surfactant. Here, we describe the adsorption characteristics of this surfactant in carbonate-formation materials. The adsorption of this surfactant is sensitive to the equilibrium pH, the electrolyte composition of the brine, and the minerals in carbonate-formation materials. Pure C12 is a nonionic surfactant. When it is mixed with brine, the solution has a high pH and limited solubility. However, when the surfactant solution in brine is equilibrated with high-pressure CO2, the pH is approximately 4; the surfactant switches to a cationic surfactant and becomes soluble. Thus, the adsorption is also a function of pH. The adsorption of C12 on calcite at low pH is low (e.g., 0.5 mg/m2). However, if the carbonate formation contains silica or clays, the adsorption is high, as is typical for cationic surfactants. The adsorption of C12 on silica decreases with an increase in divalent (Ca2+ and Mg2+) and trivalent (Al3+) cations. This is because of the competition for the negatively charged silica sites between the multivalent cations and the monovalent cationic surfactant. An additional effect of the presence of divalent cations in the brine is that it reduces the dissolution of calcite or dolomite in the presence of high-pressure CO2. The dissolution of calcite and dolomite is harmful because of formation damage and increased alkalinity. The latter raises the pH and thus increases the adsorption of C12 or even causes surfactant precipitation.
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Yan, Junzhi, Yuming Sun, Junxi Cai, et al. "Construction of ZnCdS Quantum-Dot-Modified CeO2 (0D–2D) Heterojunction for Enhancing Photocatalytic CO2 Reduction and Mechanism Insight." Catalysts 14, no. 9 (2024): 599. http://dx.doi.org/10.3390/catal14090599.
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It is important to improve the separation ability of photogenerated electrons and the adsorption capacity of carbon dioxide (CO2) for efficient photoreduction of CO2. Here, we synthesized ZnCdS quantum dots (ZCS-QDs) and cerium dioxide nanosheets (CeO2) using the solvothermal method and calcination method. We combined CeO2 and ZCS-QDs to effectively enhance the charge separation efficiency, and the lifetime of photogenerated electrons was increased 4.5 times. The CO evolution rate of the optimized composite (ZCS-QDs/CeO2) was up to 495.8 μmol g−1 h−1, and it had 100% product selectivity. In addition, the stability remained high after five cycles. The CO2 adsorption capacity of the catalyst surface was observed by in situ FTIR. The test results showed that improving CO2 capture ability and promoting photogenic electron separation had positive effects on enhancing photoreduction of CO2. This study provides a reference for constructing a zero-dimensional–two-dimensional (0D–2D) heterojunction and explores potential CO2 reduction reaction mechanisms.
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Fukuda, S., M. Matsumoto, N. Nishimura, et al. "Endothelial modulation of norepinephrine-induced constriction of rat aorta at normal and high CO2 tensions." American Journal of Physiology-Heart and Circulatory Physiology 258, no. 4 (1990): H1049—H1054. http://dx.doi.org/10.1152/ajpheart.1990.258.4.h1049.
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Endothelial modulation of norepinephrine (NE)-induced constriction of the isolated rat aorta was studied at normal (PCO2, 41 +/- 0 mmHg) and high CO2 tensions (PCO2, 91 +/- 1 mmHg). In preparations with intact endothelium, increased CO2 tension resulted in rightward shift of the NE dose-response curve with attenuation of maximal contraction. This effect of CO2 was not modified by indomethacin. Treatment with hemoglobin or rubbing of the endothelium meant that increased CO2 tension still resulted in rightward shift of the NE dose-response curve but without altering the maximal contractile response. The basal guanosine 3',5'-cyclic monophosphate (cGMP) levels in control and NE-treated aortic preparations were not affected by increasing the CO2 tension. Thus the inhibitory action of CO2 on NE-induced contraction in the presence of endothelium may not be derived from facilitation of endothelium-derived relaxation factor (EDRF)-induced cGMP synthesis. Increasing the CO2 tension attenuated the sustained contraction induced by the addition of NE and Ca2+ (2.5 mM) to intact endothelium preparations previously bathed in Ca2(+)-free solution. Further addition of Ca2+ (total 5.0 mM) did not increase the contraction. These findings suggest that the intrinsic activity of NE is greatly modified by endothelium at a high CO2 tension. Vasodilation during hypercapnia may be induced at least in part by synergistic actions of EDRF and CO2 on smooth muscle cells.
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Douglas, A. R., N. L. Jones, and J. W. Reed. "Calculation of whole blood CO2 content." Journal of Applied Physiology 65, no. 1 (1988): 473–77. http://dx.doi.org/10.1152/jappl.1988.65.1.473.
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Currently used methods for calculating whole blood CO2 content from calculated plasma content, measured blood pH, hemoglobin concentration ([Hb]), and O2 saturation yield materially different results. In this study the constants of the fundamental equations relating blood CO2 content to plasma content have been reevaluated. An iterative computer technique was used to empirically derive appropriate constants from data obtained from nine healthy male subjects at rest and at several exercise work loads. A calculation was derived that fitted the data well [difference 0.02 +/- 1.19 ml/100 (SD) ml, r = 0.98] blood CCO2 = plasma CCO2 (Formula: see text) where plasma CCO2 = 2.226.s.plasma PCO2.(1 + 10pH-pK'), CCO2 is CO2 content, SO2 is O2 saturation, s is the plasma CO2 solubility coefficient, and pK' is the apparent pK [s and pK' are from the equations of Kelman (Respir. Physiol. 3: 111-115, 1967)].
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Elmes, Victoria K., and Nichola J. Coleman. "Interactions of Cd2+, Co2+ and MoO42− Ions with Crushed Concrete Fines." Journal of Composites Science 5, no. 2 (2021): 42. http://dx.doi.org/10.3390/jcs5020042.
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Construction and demolition activities generate approximately two thirds of the world’s waste, with concrete-based demolition material accounting for the largest proportion. Primary aggregates are recovered and reused, although the cement-rich fine fraction is underutilised. In this study, single metal batch sorption experiments confirmed that crushed concrete fines (CCF) are an effective sorbent for the maximum exclusion of 45.2 mg g−1 Cd2+, 38.4 mg g−1 Co2+ and 56.0 mg g−1 MoO42− ions from aqueous media. The principal mechanisms of sorption were determined, by scanning electron microscopy of the metal-laden CCF, to be co-precipitation with Ca2+ ions released from the cement to form solubility limiting phases. The removal of Co2+ and MoO42− ions followed a zero-order reaction and that of Cd2+ was best described by a pseudo-second-order model. The Langmuir model provided the most appropriate description of the steady state immobilisation of Cd2+ and Co2+, whereas the removal of MoO42− conformed to the Freundlich isotherm. Long equilibration times (>120 h), loose floc formation and high pH are likely to limit the use of CCF in many conventional wastewater treatment applications; although, these properties could be usefully exploited in reactive barriers for the management of contaminated soils, sediments and groundwater.
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Wang, Li, Guo-Qing Yang, Xing Ren, and Zhong-Wen Liu. "CeO2-Promoted PtSn/SiO2 as a High-Performance Catalyst for the Oxidative Dehydrogenation of Propane with Carbon Dioxide." Nanomaterials 12, no. 3 (2022): 417. http://dx.doi.org/10.3390/nano12030417.
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The oxidative dehydrogenation of propane with CO2 (CO2-ODP) has been extensively investigated as a promising green technology for the efficient production of propylene, but the lack of a high-performance catalyst is still one of the main challenges for its industrial application. In this work, an efficient catalyst for CO2-ODP was developed by adding CeO2 to PtSn/SiO2 as a promoter via the simple impregnation method. Reaction results indicate that the addition of CeO2 significantly improved the catalytic activity and propylene selectivity of the PtSn/SiO2 catalyst, and the highest space-time yield of 1.75 g(C3H6)·g(catalyst)−1·h−1 was achieved over PtSn/SiO2 with a Ce loading of 6 wt%. The correlation of the reaction results with the characterization data reveals that the introduction of CeO2 into PtSn/SiO2 not only improved the Pt dispersion but also regulated the interaction between Pt and Sn species. Thus, the essential reason for the promotional effect of CeO2 on CO2-ODP performance was rationally ascribed to the enhanced adsorption of propane and CO2 originating from the rich oxygen defects of CeO2. These important understandings are applicable in further screening of promoters for the development of a high-performance Pt-based catalyst for CO2-ODP.
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Litawa, Barbara, Piotr Michorczyk, and Jan Ogonowski. "Influence of Co2 on the Catalytic Performance Of La2O3/CeO2 and CaO/CeO2 Catalysts in the Oxidative Coupling of Methane." Polish Journal of Chemical Technology 15, no. 1 (2013): 22–26. http://dx.doi.org/10.2478/pjct-2013-0005.
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In this work the La2O3/CeO2 (33 mol % of La) and CaO/CeO2 (33 mol % of Ca) catalysts were prepared by the impregnation method and characterized by XRD and CO2-TPD. The catalytic properties of the catalysts were tested in the OCM process at 1073 K using the methane/oxygen mixture of the mole ratio 3.7 or 2.5 additionally containing CO2 and helium balance. It was found that in the presence of both catalysts an addition of CO2 enhances the selectivity to the ethylene and ethane and it does not have any negative influence on methane conversion. In the case of the CaO/CeO2 catalyst the promoting effect of CO2 was the highest. When the partial pressure of CO2 equals to 39 kPa the increase in selectivity from 36 to 41% was noted while the conversion of methane equal to 19.4-19.7 %.
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Qin, Jinyi, Yifan Gong, Chuan Qin, et al. "CO2 introduced the coagulation-flocculation of oil acidized wastewater: pollutant removal and cost analysis." Water Science and Technology 83, no. 5 (2021): 1108–17. http://dx.doi.org/10.2166/wst.2021.054.
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Abstract It is difficult to adjust the pH of oil acidized wastewater rich in Ca2+, thus hindering the polyacrylamide (PAM) flocculation. This study aims at accelerating the flocculation process by introducing CO2 into the water to induce the formation of CaCO3 nuclei. The order in which CO2 and NaOH were added affected the floc structures. Compared with CO2-NaOH-PAM, the flocs of NaOH-CO2-PAM were more compact and more CaCO3 crystals were formed. The aqueous Ca2+ involved in the reaction reached 20%, and CO2 utilization was enhanced. The settling time was shortened by half (from 20 to 3 min), and NaOH consumption was reduced by one-tenth (from 0.03 to 0.003 mol), hence significantly reducing the costs. Due to the higher settling rate and shorter contact time, the NaOH-CO2-PAM flocs adsorbed less so that the residual oil was 124 mg·L−1, while in the case of CO2-NaOH-PAM it was 88 mg·L−1. As a promising coagulation aid, CO2 can also be used to mineralize pollutants in wastewater.
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LIU, HUIFENG, PING ZHANG, XIANGJIE AN, et al. "CO2 LASER PLUS PHOTODYNAMIC THERAPY VERSUS CO2 LASER IN THE TREATMENT OF CONDYLOMA ACUMINATUM: A RANDOMIZED COMPARATIVE STUDY." Journal of Innovative Optical Health Sciences 05, no. 01 (2012): 1150008. http://dx.doi.org/10.1142/s1793545811500088.
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To compare the efficacy and safety of CO2 laser plus 5-aminolevulinic acid (ALA) photodynamic therapy (PDT) with CO2 laser for the treatment of multiple condyloma acuminatum (CA), 120 patients with multiple CA were allocated into two groups — combined group ( CO2 laser plus ALA-PDT, n = 60) and CO2 laser group ( CO2 laser plus placebo-PDT, n = 60). After CO2 laser, a 20% ALA or a placebo solution was applied to the CA area 3 h before illumination with red light (635 nm, 100 mW/cm2, 80 J/cm2). The treatment was repeated seven days after the first treatment if the lesions were not completely resolved. The complete response rate, recurrence rate and adverse effects in the two groups were analyzed. After two treatments, the complete response rates in the CO2 laser group and combined group were 100% (509/509) and 100% (507/507) in the CA (p > 0.05), respectively. The recurrence rates in the CO2 laser group and combined group were 44.9% (229/509) and 10.6% (54/507) in the CA (p < 0.05), respectively. The adverse effects in CO2 laser group was more than that in combined group. The combined group is a more effective treatment for multiple CA compared with CO2 laser group. T/S. Style the highlighted text as abstract.
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Watanabe, Hirotatsu, Syo Higashidani, Aoba Tawa, Ikken Ban, and Teppei Ogura. "Oxidation Process of Ni Cathode in CO2 Electrolysis in SOEC: X-Ray and DFT Study." ECS Transactions 111, no. 6 (2023): 1319–26. http://dx.doi.org/10.1149/11106.1319ecst.
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CO2 oxidation of Ni cathode in CO2 electrolysis in solid oxide electrolysis cell (SOEC) was studied experimentally and through first-principles density functional theory (DFT) calculation. Ex-situ analyses of Ni/YSZ surface after CO2 electrolysis were performed using SEM and XRD. As a result, less oxidation of Ni was found in CO2 electrolysis mode at high current density (-280 mA/cm2), whereas Ni was oxidized at low current density (-140 mA/cm2). DFT calculation showed CO2 reduction was more stable than Ni oxidation at the Ni/YSZ interface. The electrolysis mode can enhance the oxidation tolerance of the Ni electrode due to the oxygen transfer. It was also implied that the electrolyte structure could improve the oxidation tolerance.
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Serafin, Jarosław, and Jordi Llorca. "Nanoshaped Cerium Oxide with Nickel as a Non-Noble Metal Catalyst for CO2 Thermochemical Reactions." Molecules 28, no. 7 (2023): 2926. http://dx.doi.org/10.3390/molecules28072926.
Full textAbstract:
Four different nanoshapes of cerium dioxide have been prepared (polycrystals, rods, cubes, and octahedra) and have been decorated with different metals (Ru, Pd, Au, Pt, Cu, and Ni) by incipient wetness impregnation (IWI) and ball milling (BM) methods. After an initial analysis based on oxygen consumption from CO2 pulse chemisorption, Ni-like metal, and two forms of CeO2 cubes and rods were selected for further research. Catalysts were characterized using the Brunauer-Emmett-Teller formula (BET), X-ray spectroscopy (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–visible spectrophotometry (UV-Vis), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (H2-TPR) and CO2 pulse chemisorption, and used to reduce of CO2 into CO (CO2 splitting). Adding metals to cerium dioxide enhanced the ability of CeO2 to release oxygen and concomitant reactivity toward the reduction of CO2. The effect of the metal precursor and concentration were evaluated. The highest CO2 splitting value was achieved for 2% Ni/CeO2-rods prepared by ball milling using Ni nitrate (412 µmol/gcat) and the H2 consumption (453.2 µmol/gcat) confirms the good redox ability of this catalyst.
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Bartz, Marie Luise Carolina, George Gardner Brown, Amarildo Pasini, et al. "Earthworm communities in organic and conventional coffee cultivation." Pesquisa Agropecuária Brasileira 44, no. 8 (2009): 928–33. http://dx.doi.org/10.1590/s0100-204x2009000800019.
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The objective of this work was to evaluate the effect of organic and conventional coffee crops on biomass, population density and diversity of earthworms, in Lerroville, district of Londrina County, Paraná state, Brazil. Earthworm communities were sampled in three areas with organic coffee cultivation (CO1, CO2 and CO3), two with conventional coffee (CC1 and CC2), and a native forest fragment (MT). The soil of the areas CO1, CC1, and MT was classified as Nitossolo Vermelho (Rhodic Kandiudox), while CO2, CO3, and CC2 were on Latossolo Vermelho (Rhodic Hapludox). Eight samples were taken in each area on two occasions, winter and summer, using the Tropical Soil Biology and Fertility (TSBF) method in the 0-20 cm soil layer. The earthworms were handsorted and preserved in 4% formaldehyde, and were later weighed, counted and identified. The highest earthworm biomass, both in winter and summer, occurred in the CO3 area. For population density, the higher numbers of individuals were found in CO1 and CO3. The highest number of species was identified in the organic cultivation. The adoption of organic practices in coffee cultivation favored the diversity, density and biomass of earthworm communities.
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Mertzlufft, F. O., L. Brandt, M. Stanton-Hicks, and W. Dick. "Arterial and Mixed Venous Blood Gas Status during Apnoea of Intubation — Proof of the Christiansen-Douglas-Haldane Effect in Vivo." Anaesthesia and Intensive Care 17, no. 3 (1989): 325–31. http://dx.doi.org/10.1177/0310057x8901700314.
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The Christiansen-Douglas-Haldane effect, in short the Haldane effect, describes the dependence of the CO2 binding of blood on the degree of oxygenation of haemoglobin. Under the physiological conditions of an ‘open’ system between blood and alveoli the partial pressure of arterial C02 (PaCO2), must be less than that of mixed venous blood (P[Formula: see text]CO2). During the unphysiological conditions of a ‘closed’ system, e.g. hyperoxic apnoea, i.e. continuous oxygen uptake without CO2 delivery by the lungs, the Paco2 will not only approximate the P[Formula: see text]CO2 but will even exceed it. Without the Haldane effect, rapid adjustment of Paco2 to P[Formula: see text]CO2 would be expected during apnoea due to the lack of CO2 excretion. If however, as undertaken in this study, ongoing oxygenation (high alveolar Po2 (PACO2) with concomitant lack of C02 delivery (apnoea, i. e. the C02 concentration remains constant) lead to a continuing sufficient oxygenation of blood during its passage through the lung capillaries, then this leads to a rightwards shift of the CO2 binding curve — the Haldane effect. The resulting increase in Pco2 as shown here actually leads to an arterial-mixed venous CO2 partial pressure difference (a[Formula: see text]DPco2) of 2.8±1.8 mmHg. The results described substantiate for the first time the existence of the Haldane effect under clinical conditions.
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Lim, Dea-Won, Byeong-Soo Choi, Jin-Woo Kim, et al. "Separation Characteristics of CO2 from CO2/CH4 Mixed Gas using PSA Process." Journal of Korea Society of Waste Management 31, no. 6 (2014): 609–15. http://dx.doi.org/10.9786/kswm.2014.31.6.609.
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Vargas-Sánchez, Mariana, Javier Alcocer, Eric Puche, and Salvador Sánchez-Carrillo. "Abiotic processes control carbon dioxide dynamics in temperate karst lakes." PeerJ 12 (May 22, 2024): e17393. http://dx.doi.org/10.7717/peerj.17393.
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Inland waters are crucial in the carbon cycle, contributing significantly to the global CO2 fluxes. Carbonate lakes may act as both sources and sinks of CO2 depending on the interactions between the amount of dissolved inorganic carbon (DIC) inputs, lake metabolisms, and geochemical processes. It is often difficult to distinguish the dominant mechanisms driving CO2 dynamics and their effects on CO2 emissions. This study was undertaken in three groundwater-fed carbonate-rich lakes in central Spain (Ruidera Lakes), severely polluted with nitrates from agricultural overfertilization. Diel and seasonal (summer and winter) changes in CO2 concentration (CCO2) DIC, and CO2 emissions-(FCO2)-, as well as physical and chemical variables, including primary production and phytoplanktonic chlorophyll-a were measured. In addition, δ13C-DIC, δ13C-CO2 in lake waters, and δ13C of the sedimentary organic matter were measured seasonally to identify the primary CO2 sources and processes. While the lakes were consistently CCO2 supersaturated and FCO2 was released to the atmosphere during both seasons, the highest CCO2 and DIC were in summer (0.36–2.26 µmol L–1). Our results support a strong phosphorus limitation for primary production in these lakes, which impinges on CO2 dynamics. External DIC inputs to the lake waters primarily drive the CCO2 and, therefore, the FCO2. The δ13C-DIC signatures below –12‰ confirmed the primary geogenic influence on DIC. As also suggested by the high values on the calcite saturation index, the Miller-Tans plot revealed that the CO2 source in the lakes was close to the signature provided by the fractionation of δ13C-CO2 from calcite precipitation. Therefore, the main contribution behind the CCO2 values found in these karst lakes should be attributed to the calcite precipitation process, which is temperature-dependent according to the seasonal change observed in δ13C-DIC values. Finally, co-precipitation of phosphate with calcite could partly explain the observed low phytoplankton production in these lakes and the impact on the contribution to increasing greenhouse gas emissions. However, as eutrophication increases and the soluble reactive phosphorus (SRP) content increases, the co-precipitation of phosphate is expected to be progressively inhibited. These thresholds must be assessed to understand how the CO32− ions drive lake co-precipitation dynamics. Carbonate regions extend over 15% of the Earth’s surface but seem essential in the CO2 dynamics at a global scale.
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Müller, T. H., D. Swandulla, and H. D. Lux. "Activation of three types of membrane currents by various divalent cations in identified molluscan pacemaker neurons." Journal of General Physiology 94, no. 6 (1989): 997–1014. http://dx.doi.org/10.1085/jgp.94.6.997.
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We investigated membrane currents activated by intracellular divalent cations in two types of molluscan pacemaker neurons. A fast and quantitative pressure injection technique was used to apply Ca2+ and other divalent cations. Ca2+ was most effective in activating a nonspecific cation current and two types of K+ currents found in these cells. One type of outward current was quickly activated following injections with increasing effectiveness for divalent cations of ionic radii that were closer to the radius of Ca2+ (Ca2+ greater than Cd2+ greater than Hg2+ greater than Mn2+ greater than Zn2+ greater than Co2+ greater than Ni2+ greater than Pb2+ greater than Sr2+ greater than Mg2+ greater than Ba2+). The other type of outward current was activated with a delay by Ca2+ greater than Sr2+ greater than Hg2+ greater than Pb2+. Mg2+, Ba2+, Zn2+, Cd2+, Mn2+, Co2+, and Ni2+ were ineffective in concentrations up to 5 mM. Comparison with properties of Ca2(+)-sensitive proteins related to the binding of divalent cations suggests that a Ca2(+)-binding protein of the calmodulin/troponin C type is involved in Ca2(+)-dependent activation of the fast-activated type of K+ current. Th sequence obtained for the slowly activated type is compatible with the effectiveness of different divalent cations in activating protein kinase C. The nonspecific cation current was activated by Ca2+ greater than Hg2+ greater than Ba2+ greater than Pb2+ greater than Sr2+, a sequence unlike sequences for known Ca2(+)-binding proteins.
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Kiefmann, Martina, Sascha Tank, Marc-Oliver Tritt, et al. "Dead space ventilation promotes alveolar hypocapnia reducing surfactant secretion by altering mitochondrial function." Thorax 74, no. 3 (2019): 219–28. http://dx.doi.org/10.1136/thoraxjnl-2018-211864.
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BackgroundIn acute respiratory distress syndrome (ARDS), pulmonary perfusion failure increases physiologic dead space ventilation (VD/VT), leading to a decline of the alveolar CO2 concentration [CO2]iA. Although it has been shown that alveolar hypocapnia contributes to formation of atelectasis and surfactant depletion, a typical complication in ARDS, the underlying mechanism has not been elucidated so far.MethodsIn isolated perfused rat lungs, cytosolic or mitochondrial Ca2+ concentrations ([Ca2+]cyt or [Ca2+]mito, respectively) of alveolar epithelial cells (AECs), surfactant secretion and the projected area of alveoli were quantified by real-time fluorescence or bright-field imaging (n=3–7 per group). In ventilated White New Zealand rabbits, the left pulmonary artery was ligated and the size of subpleural alveoli was measured by intravital microscopy (n=4 per group). Surfactant secretion was determined in the bronchoalveolar lavage (BAL) by western blot.ResultsLow [CO2]iA decreased [Ca2+]cyt and increased [Ca2+]mito in AECs, leading to reduction of Ca2+-dependent surfactant secretion, and alveolar ventilation in situ. Mitochondrial inhibition by ruthenium red or rotenone blocked these responses indicating that mitochondria are key players in CO2 sensing. Furthermore, ligature of the pulmonary artery of rabbits decreased alveolar ventilation, surfactant secretion and lung compliance in vivo. Addition of 5% CO2 to the inspiratory gas inhibited these responses.ConclusionsAccordingly, we provide evidence that alveolar hypocapnia leads to a Ca2+ shift from the cytosol into mitochondria. The subsequent decline of [Ca2+]cyt reduces surfactant secretion and thus regional ventilation in lung regions with high VD/VT. Additionally, the regional hypoventilation provoked by perfusion failure can be inhibited by inspiratory CO2 application.
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Gaurina-Međimurec, Nediljka, and Karolina Novak Mavar. "DEPLETED HYDROCARBON RESERVOIRS AND CO2 INJECTION WELLS –CO2 LEAKAGE ASSESSMENT." Rudarsko-geološko-naftni zbornik 32, no. 2 (2017): 15–26. http://dx.doi.org/10.17794/rgn.2017.2.3.
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Kuwer, Pushpmala, Anshul Yadav, and Pawan Kumar Labhasetwar. "Adsorption of cupric, cadmium and cobalt ions from the aqueous stream using the composite of iron(II,III) oxide and zeolitic imidazole framework-8." Water Science and Technology 84, no. 9 (2021): 2288–303. http://dx.doi.org/10.2166/wst.2021.452.
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Abstract In recent research, the composite of Fe3O4 and metal-organic frameworks have shown great potential in removing potentially toxic metals from water. We conducted the adsorption studies of potentially toxic metal ions (Cu2+, Co2+ and Cd2+) using the composite of Fe3O4 and zeolitic imidazole framework-8 (Fe3O4@ZIF-8) for the first time. The solvothermal technique was used to synthesize the Fe3O4. The magnetic ZIF-8 offers high thermal stability, greater adsorption surface, good removability, and high chemical and thermal stability. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) were used to characterize the synthesized samples. The SEM and XRD results revealed the high purity and structural integrity of ZIF-8 crystallites. To remove potentially toxic metals (Cu2+, Co2+ and Cd2+), the influence of adsorbent dosage, contact time, pH, and adsorbate concentration on the adsorption performance of Fe3O4@ZIF-8 was investigated. The Langmuir isotherm accurately represented the adsorption processes, with absorption magnitudes of Fe3O4@ZIF-8 determined to be 46.82 mg g−1, 71.29 mg g−1 and 54.49 mg g−1 for Cu2+, Co2+ and Cd2+, respectively. According to the adsorption mechanism analysis, the primary Cu2+, Co2+ and Cd2+ removal methods of Fe3O4@ZIF-8 were ion exchange and coordination bonds. The uptake capacity of Cu2+, Co2+ and Cd2+ solution by Fe3O4@ZIF-8 were not significantly affected by the presence of counter ions. The material exhibited superior regenerative properties for Cu2+, Co2+ and Cd2+ ions from water for up to three cycles. This study concluded that the Fe3O4@ZIF-8 could be a viable candidate for eliminating potentially toxic metals (Cu2+, Co2+ and Cd2+).
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Hamad, Shahnaz Abdulhamid, Hikmat Ali Mohamad, Rezan Ali Saleh, and Hero Farhad Salah. "Synthesis, Characterization, and Antibacterial Evaluation of Novel Binuclear Co(II) Complex Based on Thiosemicarbazone Derivative." JOURNAL OF UNIVERSITY OF BABYLON for Pure and Applied Sciences 32, no. 4 (2024): 328–45. https://doi.org/10.29196/jubpas.v32i4.5541.
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Background: Extended exposure to antimicrobial drugs can lead to genetic changes in pathogens, resulting in resistance to specific antibiotics and posing significant public health challenges. This study aims to address this issue by synthesizing and characterizing a novel Co(II) complex with ((2,2'-(7,7'-dimethyl-2,2'-dioxo-1,1',2,2'-tetrahydro-3H,3'H-5,5'-biindole-3,3'-diylidene)dihydrazinecar bothioamide), denoted as ligand(L). The potential antibiotic activity of this complex is evaluated in vitro against three pathogens: E. coli ATCC 25922, P. mirabilis ATCC 14153, and S. pneumoniae ATCC 49619. Methods: The novel Co(II) complex [Co2 (L)Cl2] was synthesized by reacting one mole of L with 2 moles of CoCl2, yielding the general formula [Co2LCl2]. Characterization was performed using FT-IR, 1H-NMR, UV-visible spectra, and elemental analysis (CHNS). The antimicrobial activity was evaluated by determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Additionally, the synergistic effects of L and [Co2(L)Cl2] complex with ciprofloxacin (Cip) were tested against E. coli and P. mirabilis. Results: The characterization confirmed the structure of the [Co2(L)Cl2] complex, indicating successful coordination via nitrogen, oxygen, and sulfur, exhibiting a square planar geometry. Both the L and [Co2(L)Cl2] complex exhibited antimicrobial activity against the tested pathogens. Additionally, when used in combination with ciprofloxacin, both the L and the [Co2(L)Cl2] complex showed synergistic effects against E. coli and P. mirabilis, with the [Co2(L)Cl2] complex exhibiting greater efficacy. Conclusions: The novel [Co2(L)Cl2] complex demonstrated higher antimicrobial activity than the L and showed synergistic effects with ciprofloxacin against specific pathogens. As a result of this study, these two compounds show potential as antibacterial drugs.
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Pertuit, A. J., and P. J. Vergano. "EFFECT OF MODIFIED ATMOSPHERE PACKAGING ON CARNATION." HortScience 27, no. 11 (1992): 1178h—1178. http://dx.doi.org/10.21273/hortsci.27.11.1178h.
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Cut carnation (Dianthus caryophyllus) `White Sim' flowers from Columbia (South America), nontreated or dipped for three seconds in water or 9.5 g/1 benlate (DuPont) or 3336 (Cleary), were placed in “orchid tubes” and remained in air or were packaged in barrier bags of air or 10% CO2/10%O2 (80%N2). Postharvest life (days) was recorded, and the CO2, O2, and CH2=CH2 concentrations within the bags were monitored with gas chromatographs. Controls, nonsealed and in air, did not differ in postharvest life, indicating no benefit from a fungicide dip (P= 0.05). Botrytis was not observed in this test. Flowers sealed in bags did not differ in postharvest life (P= 0.05); however, when a single degree of freedom comparison was made (PR>F: 0.0001), their postharvest life was longer than controls (5.8 vs. 3.1 days). In bags, CO2 increased and O2 decreased over time, CO2 remaining higher and O2 lower with the 10%CO2/10% O2 treatment. CH2=CH2 increased to 4 ppm over 10 days, but ppm within bag treatments did not vary on any day (P= 0.05).
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Pereyda-González, Jade M., Clelia De-la-Peña, Wilmer Tezara, et al. "High Temperature and Elevated CO2 Modify Phenology and Growth in Pepper Plants." Agronomy 12, no. 8 (2022): 1836. http://dx.doi.org/10.3390/agronomy12081836.
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The aim of this study was to determine the effect of temperature and CO2 on seed emergence, seedling quality, and phenological stage of Capsicum chinense and Capsicum annum cultivated in four controlled growth chambers (C1: 30 °C and 400 μmol CO2 mol−1; C2: 40 °C and 1200 μmol CO2 mol−1; C3: 30 °C and 1200 μmol CO2 mol−1; C4: 40 °C and 400 μmol CO2 mol−1). Neither temperature nor elevated CO2 influenced seed emergence, although differences were observed in seedling mortality, with high temperature affecting seedling survival in both species; the mortality rate at 40 °C was 20 and 53% in C. annuum and 45 and 58% in C. chinense at 400 and 1200 μmol CO2 mol−1, respectively. Differences were also observed in growth parameters, where positive effects were observed on leaf area, which reached 45.9 cm2 in C. annuum and 23.9 cm2 in C. chinense with elevated CO2 at 30 °C, but negative effects were observed with high temperature. CO2 enrichment increased flower and fruit production per plant. However, high temperature delayed flower phenology, increased flower abortion and inhibited fruit set. Elevated CO2 counteracted the detrimental effects of high temperature on growth parameters and flower number, but this was not sufficient to prevent flower abortion and the detrimental morphological characteristics of fruit caused by a temperature of 40 °C.