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1.
Yu Huan Shouxiao Chen Rui Zeng Tao Wei Dehua Dong Xun Hu Yunhui Huang 《Liver Transplantation》2019,9(29)
Unveiling the intrinsic effects of Ruddlesden‐Popper (RP) series An+1BnO3n+1 (A = La, B = Ni, Co, Mn, Cu, n = 1, 2 and 3) catalysts is essential in order to optimize the activity of oxygen reduction reaction (ORR) and evolution reaction (OER). Here, it is demonstrated that the oxygen vacancy is not the key point for RP to realize high ORR and OER activity at high temperature. Instead, interstitial O2? with high concentration and fast migration, and lattice oxygen with high activity are favorable for the high‐temperature catalytic activity. Aliovalent cation doping is an effective strategy to modify the catalytic activity. For the RP catalysts, low‐valence ion doping does not introduce oxygen vacancies, which suppresses the activity of lattice oxygen and decreases the interstitial O2? concentration; whereas high‐valence ion doping enhances the interstitial O2– concentration and the lattice oxygen activity. The evaluations of six RP series (La2NiO4, La2CoO4, La3Co2O7, La4Ni3O10, La2MnO4, and La2CuO4 based) and twenty samples as oxygen electrodes for solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) demonstrate that this finding is applicable to all the selected RP series. 相似文献
2.
U. Stottmeister 《Engineering in Life Science》1986,6(1):69-75
The determination of oxygen diffusion coefficients was carried out by a modified chronoamperometric method using a stationary platinum electrode. The determined diffusion coefficients are related to approximated η0-values. It was shown a relation of Di and η0 according to the HAYDUK-CHENG-potential equation. That means a strong relative lowering of oxygen diffusion coefficients already by low viscosities, but a little influence at high viscosities. A simple laboratory thin film reactor is described, in which the oxygen supply is maintained by diffusion. This reactor is suitable very well for fermentations of viscous fluids. 相似文献
3.
Background
Hydrogenases catalyze reversible reaction between hydrogen (H2) and proton. Inactivation of hydrogenase by exposure to oxygen is a critical limitation in biohydrogen production since strict anaerobic conditions are required. While [FeFe]-hydrogenases are irreversibly inactivated by oxygen, it was known that [NiFe]-hydrogenases are generally more tolerant to oxygen. The physiological function of [NiFe]-hydrogenase 1 is still ambiguous. We herein investigated the H2 production potential of [NiFe]-hydrogenase 1 of Escherichia coli in vivo and in vitro. The hya A and hya B genes corresponding to the small and large subunits of [NiFe]-hydrogenase 1 core enzyme, respectively, were expressed in BL21, an E. coli strain without H2 producing ability. 相似文献4.
Field studies of respiration in stream insects are few in comparison with laboratory studies. To evaluate the influence of temperature and oxygen along altitudinal gradients we measured the respiration rate of fully acclimatized larval Trichoptera, Plecoptera and Ephemeroptera under similar field conditions in streams from 400 to 3800 m above sea level in tropical Ecuador. Mean active respiration rates of the animals at 3800 m were approximately half of those at 400 m. Trichoptera showed a slightly larger difference in respiration with altitude than Ephemeroptera. Comparative respiration measurements at 100 and 50% oxygen saturation indicated that highland animals reduced their oxygen uptake more than their counterparts in the lowland when oxygen availability decreased. The temperature response of respiration calculated between the insect assemblages at different altitudes showed a mean assemblage Q10−value of 1.50. Trichopteran larvae had a slightly stronger temperature response (Q10 of 1.68) than ephemeropterans (Q10 of 1.30). These community Q10-values are considerably lower than the mean value of 2.36 found in single species in the laboratory. The weak community-wide response of respiration to temperature in tropical streams is probably due to full acclimatization of the component species to stable and narrow temperature ranges. Adaptations to the low oxygen availability at high altitude probably consist of a suite of genetic physiological and behavioural features. 相似文献
5.
Lakhal R Auria R Davidson S Ollivier B Durand MC Dolla A Hamdi M Combet-Blanc Y 《Archives of microbiology》2011,193(6):429-438
6.
7.
Operando Lithium Dynamics in the Li‐Rich Layered Oxide Cathode Material via Neutron Diffraction
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Haodong Liu Yan Chen Sunny Hy Ke An Subramanian Venkatachalam Danna Qian Minghao Zhang Ying Shirley Meng 《Liver Transplantation》2016,6(7)
Neutron diffraction under operando battery cycling is used to study the lithium and oxygen dynamics of high Li‐rich Li(Lix/3Ni(3/8‐3x/8)Co(1/4‐x/4)Mn(3/8+7x/24)O2 (x = 0.6, HLR) and low Li‐rich Li(Lix/3Ni(1/3‐x/3)Co(1/3‐x/3)Mn(1/3+x/3)O2 (x = 0.24, LLR) compounds that exhibit different degrees of oxygen activation at high voltage. The measured lattice parameter changes and oxygen position show largely contrasting changes for the two cathodes where the LLR exhibits larger movement of oxygen and lattice contractions in comparison to the HLR that maintains relatively constant lattice parameters and oxygen position during the high voltage plateau until the end of charge. Density functional theory calculations show the presence of oxygen vacancy during the high voltage plateau; changes in the lattice parameters and oxygen position are consistent with experimental observations. Lithium migration kinetics for the Li‐rich material is observed under operando conditions for the first time to reveal the rate of lithium extraction from the lithium layer, and transition metal layer is related to the different charge and discharge characteristics. At the beginning of charging, the lithium extraction predominately occurs within the lithium layer. Once the high voltage plateau is reached, the lithium extraction from the lithium layer slows down and extraction from the transition metal layer evolves at a faster rate. 相似文献
8.
A. A. Zotin 《Biology Bulletin》2010,37(6):596-604
Changes in the rate and intensity of oxygen consumption during individual ontogeny of 14 specimens of Lymnaea stagnalis in the period from the 10th week after emergence until death was investigated in aquaculture. It was demonstrated that the
rate of oxygen consumption increased and the intensity of this process decreased during the whole period of observations.
Alterations of these parameters were accompanied with permanent oscillations of their meanings. The correlation between intensity
of oxygen consumption (q) and age (t) can be described with the equation q = q
st/(1-exp(−k
g
(t+t
0))). The values of coefficients of this equation do not differ significantly between individuals and, on average, comprise
k
g
= 0.0696 ± 0.0072 weeks−1; q
st = 60.4 ± 2.6 mcl O2/(h · g); t
0 = −3.0 ± 0.7 weeks. The dependence of the rate of oxygen consumption (Q, μl O2/h) on body weight (M, g) for all data is significantly described with the allometric equation Q = 0.369M
0.779. 相似文献
9.
Cooper CE Withers PC 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2004,174(2):107-111
This study examines the ventilatory physiology of the numbat (Myrmecobius fasciatus), a small to medium-sized (550 g) termitivorous marsupial. Ventilatory parameters at thermoneutrality reflect the slightly low (83% of predicted) basal metabolic rate of the numbat, with ventilation frequency (ƒR; 30.6±3.65 breaths min–1), tidal volume [VT; 6.0±0.66 ml at body temperature and pressure, saturated (BTPS)] and consequently minute volume (VI; 117.7±15.22 ml min–1; BTPS) all being 80–87% of that expected for a marsupial of similar body mass. Oxygen extraction was 27.7±1.37% in the thermoneutral zone. As is typical of marsupials, numbats accommodated increased oxygen consumption rates at ambient temperatures (T
a) below the thermoneutral zone by increasing minute volume (up to 411.2±43.98 ml min–1; BTPS at T
a=10 °C) rather than oxygen extraction. Minute volume at 10 °C increased more by changes in ventilation frequency (up to 45.5±4.85 breaths min–1) than tidal volume (9.4±1.03 ml, BTPS), as is also typical for a small-medium sized marsupial.Abbreviations
BMR
basal metabolic rate
-
BTPS
body temperature and pressure, saturated
-
EO
2
oxygen extraction
-
ƒ
R
ventilation frequency
-
STPD
standard temperature and pressure, dry
-
T
a
ambient temperature
-
T
b
body temperature
-
TNZ
thermoneutral zone
-
V
I
minute volume
-
V
T
tidal volume
-
O
2
oxygen consumption rate
Communicated by I.D. Hume 相似文献
10.
Quinn P. Fitzgibbon Roger S. Seymour Jeffery Buchanan Richard Musgrove John Carragher 《Environmental Biology of Fishes》2010,89(1):59-69
Of the few measurements of the behavioural and physiological responses of tuna to hypoxia, most are restricted to shallow
diving tropical species. Furthermore, when wild tuna experience low dissolved oxygen, they are likely to have an increased
oxygen demand associated with the metabolic cost of food digestion and assimilation (specific dynamic action). However the
response of postprandial tuna to hypoxia has never been examined. This study focuses on the metabolic and behavioural responses
of both fasted and postprandial southern bluefin tuna (Thunnus maccoyii) to low dissolved oxygen. Fasted T. maccoyii were exposed to dissolved oxygen levels of 4.44, 3.23, 2.49 and 1.57 mg·l−1 for 20–21 h. In moderate hypoxia (4.44 and 3.23 mg·l−1), swimming speed was enhanced (1.5 and 1.3 times normoxic speed, respectively) presumably to increase ventilation volume.
Routine metabolic rate (R
r
) was similarly elevated (1.3 and 1.2 times normoxic R
r
, respectively), most likely due to increased metabolic demand of faster swimming. At 2.49 mg·l−1, swimming speed increased to over double the normoxic speed, possibly as an escape response. At 1.57 mg·l−1, both swimming speed and R
r
were reduced (0.8 and 0.9 times normoxic level, respectively), and tuna failed to survive the entire 20 h exposure period.
This reveals that the critical oxygen level of T. maccoyii is between 1.57 and 2.49 mg·l−1, demonstrating that they are remarkably well adapted to low dissolved oxygen. Feeding did not greatly influence their hypoxia
tolerance with tuna surviving exposure to dissolved oxygen levels of 2.96 and 1.81 mg·l−1 for 21 h, after ingesting a ration of 6.7% body weight of sardines (Sardinops sagax). In a subsequent experiment to determine the effects of hypoxia on digestion rate, T. maccoyii were fed to satiation and exposed to a dissolved oxygen level of 2.84 mg·l−1 for 6.5–8 h. There was no significant difference in swimming speed, R
r
and gastric evacuation rates of tuna in hypoxia compared to those in normoxia. This demonstrates that in moderate to severe
hypoxia, T. maccoyii are still capable of aerobically supporting maintenance metabolism, routine swimming and specific dynamic action. It is hypothesized
that adaptations which support the large metabolic scope of tuna are also likely to be beneficial for oxygen extraction and
delivery in conditions of hypoxia. 相似文献
11.
12.
Ting Xiong Zhi Gen Yu Haijun Wu Yonghua Du Qidong Xie Jingsheng Chen Yong‐Wei Zhang Stephen John Pennycook Wee Siang Vincent Lee Junmin Xue 《Liver Transplantation》2019,9(14)
A major limitation of MnO2 in aqueous Zn/MnO2 ion battery applications is the poor utilization of its electrochemical active surface area. Herein, it is shown that by generating oxygen vacancies (VO) in the MnO2 lattice, Gibbs free energy of Zn2+ adsorption in the vicinity of VO can be reduced to thermoneutral value (≈0.05 eV). This suggests that Zn2+ adsorption/desorption process on oxygen‐deficient MnO2 is more reversible as compared to pristine MnO2. In addition, because of the fact that fewer electrons are needed for Zn? O bonding in oxygen‐deficient MnO2, more valence electrons can be contributed into the delocalized electron cloud of the material, which aids in enhancing the attainable capacity. As a result, the stable Zn/oxygen‐deficient MnO2 battery is able to deliver one of the highest capacities of 345 mAh g?1 reported for a birnessite MnO2 system. This excellent electrochemical performance suggests that generating oxygen vacancies in MnO2 may aid in the future development of advanced cathodes for aqueous Zn ion batteries. 相似文献
13.
The time delay of oxygen probe response to the signal from a fermenter makes identification of the volumetric oxygen transfer coefficient kLa by the dynamic method more complicated. A coupled model involving the transient-state oxygen balance of the fermenter together with the dynamic model of the oxygen probe must be then formulated, solved and identified. In this paper two simple models of air-lift loop fermenters have been proposed and a coupled mathematical model of the fermenter – oxygen probe system has been developed. The identification procedure was used to estimate kLa values in the fermenter with internal circulation flow on the basis of experimental measurements. A comparison of evaluated and experimental indications of the probes placed at various heights of the column proves that the model presented gives a possibility of the first-step approximation of kLa in loop fermenters. 相似文献
14.
Cytochrome bd from Escherichia coli is able to oxidize such substrates as guaiacol, ferrocene, benzohydroquinone, and potassium ferrocyanide through the peroxidase
mechanism, while none of these donors is oxidized in the oxidase reaction (i.e. in the reaction that involves molecular oxygen
as the electron acceptor). Peroxidation of guaiacol has been studied in detail. The dependence of the rate of the reaction
on the concentration of the enzyme and substrates as well as the effect of various inhibitors of the oxidase reaction on the
peroxidase activity have been tested. The dependence of the guaiacol-peroxidase activity on the H2O2 concentration is linear up to the concentration of 8 mM. At higher concentrations of H2O2, inactivation of the enzyme is observed. Guaiacol markedly protects the enzyme from inactivation induced by peroxide. The
peroxidase activity of cytochrome bd increases with increasing guaiacol concentration, reaching saturation in the range from 0.5 to 2.5 mM, but then starts falling.
Such inhibitors of the ubiquinol-oxidase activity of cytochrome bd as cyanide, pentachlorophenol, and 2-n-heptyl 4-hydroxyquinoline-N-oxide also suppress its guaiacol-peroxidase activity; in contrast, zinc ions have no influence
on the enzyme-catalyzed peroxidation of guaiacol. These data suggest that guaiacol interacts with the enzyme in the center
of ubiquinol binding and donates electrons into the di-heme center of oxygen reduction via heme b
558, and H2O2 is reduced by heme d. Although the peroxidase activity of cytochrome bd from E. coli is low compared to peroxidases, it might be of physiological significance for the bacterium itself and plays a pathophysiological
role for humans and animals. 相似文献
15.
Zhengyan Lun Bin Ouyang Daniil A. Kitchaev Raphaële J. Clment Joseph K. Papp Mahalingam Balasubramanian Yaosen Tian Teng Lei Tan Shi Bryan D. McCloskey Jinhyuk Lee Gerbrand Ceder 《Liver Transplantation》2019,9(2)
The recent discovery of Li‐excess cation‐disordered rock salt cathodes has greatly enlarged the design space of Li‐ion cathode materials. Evidence of facile lattice fluorine substitution for oxygen has further provided an important strategy to enhance the cycling performance of this class of materials. Here, a group of Mn3+–Nb5+‐based cation‐disordered oxyfluorides, Li1.2Mn3+0.6+0.5xNb5+0.2?0.5xO2?xFx (x = 0, 0.05, 0.1, 0.15, 0.2) is investigated and it is found that fluorination improves capacity retention in a very significant way. Combining spectroscopic methods and ab initio calculations, it is demonstrated that the increased transition‐metal redox (Mn3+/Mn4+) capacity that can be accommodated upon fluorination reduces reliance on oxygen redox and leads to less oxygen loss, as evidenced by differential electrochemical mass spectroscopy measurements. Furthermore, it is found that fluorine substitution also decreases the Mn3+‐induced Jahn–Teller distortion, leading to an orbital rearrangement that further increases the contribution of Mn‐redox capacity to the overall capacity. 相似文献
16.
Anion Doping: A New Strategy for Developing High‐Performance Perovskite‐Type Cathode Materials of Solid Oxide Fuel Cells
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Overcoming the sluggish activity of cathode materials is critical to realizing the wide‐spread application of intermediate‐temperature solid oxide fuel cells. Herein, a new way is reported to tune the performance of perovskite‐type materials as oxygen reduction electrodes by embedding anions (F?) in oxygen sites. The obtained perovskite oxyfluorides SrFeO3?σ ?δ Fσ and SrFe0.9Ti0.1O3?σ ?δ Fσ (σ = 0.05 and 0.10) show improved electrocatalytic activity compared to their parent oxides, achieving area specific resistance values of 0.875, 0.393, and 0.491 Ω cm2 for SrFeO3?δ , SrFeO2.95?δ F0.05, and SrFeO2.90?δ F0.10, respectively, at 600 °C in air. Such improved performance is a result of the improved bulk diffusion and surface exchange properties due to anion doping. Moreover, favorable stability in performance is also demonstrated for the F? anion‐doped perovskites as oxygen reduction electrodes at 650 °C for a test period of ≈200 h. A combination of anion doping and cation doping may provide a highly attractive strategy for the future development of cathode materials. 相似文献
17.
Jotaro Igarashi Kazuo Kobayashi Ariki Matsuoka 《Journal of biological inorganic chemistry》2011,16(4):599-609
Abstract
Truncated hemoglobins (trHbs) are distributed from bacteria to unicellular eukaryotes and have roles in oxygen transport and nitric oxide detoxification. It is known that trHbs exist in ciliates of the Tetrahymena group, but trHb structure and function remain poorly understood. To investigate trHb function with respect to stability of bound oxygen and protein structure, we measured the oxygen binding kinetics of Tetrahymena pyriformis trHb, and determined the crystal structure of the protein. The O2 association and dissociation rate constants of T. pyriformis trHb were 5.5 μM−1 s−1 and 0.18 s−1, respectively. The autooxidation rate constant was 3.8 × 10−3 h−1. These values are similar to those of HbN from Mycobacterium tuberculosis. The three-dimensional structure of an Fe(II)–O2 complex of T. pyriformis trHb was determined at 1.73-? resolution. Tyr25 (B10) and Gln46 (E7) were hydrogen-bonded to a heme-bound O2 molecule. Tyr25 donated a hydrogen bond to the terminal oxygen atom, whereas Gln46 hydrogen-bonded to the proximal oxygen atom. Furthermore, Tyr25 was hydrogen-bonded to the Gln46 and Gln50 (E11) residues. Mutations at Tyr25, Gln46, and Gln50 increased the O2 dissociation and autooxidation rate constants. An Fe(III)–H2O complex of T. pyriformis trHb was formed following reaction of the Fe(II)–O2 complex of T. pyriformis trHb, in a crystal state, with nitric oxide. This suggests that T. pyriformis trHb functions in nitric oxide detoxification. 相似文献18.
19.
Youngwan Seo 《Biotechnology and Bioprocess Engineering》2010,15(3):400-406
The scavenging activity of the flower buds of Magnolia denudata Desrousseaux on reactive oxygen species (ROS) was evaluated using 2′,7′-dichlorofluorescin diacetate (DCFH-DA) in HT 1080
cells. Methanol (MeOH) and dichloromethane (CH2Cl2) extracts inhibited dose-dependently generation of ROS in the cellular system. MeOH and CH2Cl2 extracts were combined and fractionated with n-hexane, 85% aqueous MeOH, and n-butanol (n-BuOH). Both n-hexane-soluble and 85% aqueous-soluble fractions showing strong radical-scavenging activity in the cellular system were further
separated by diverse chromatographic methods to give five known lignans (1–5). All these compounds exhibited significant radical-scavenging effect on intracellular ROS in a dose-dependent manner. Their
scavenging activity on various reactive oxygen species (ROS) was also evaluated using electron spin resonance (ESR) spin-trap
techniques. 相似文献
20.
Hana Nůsková Marek Vrbacký Zdeněk Drahota Josef Houštěk 《Journal of bioenergetics and biomembranes》2010,42(5):395-403
The mechanism of cyanide’s inhibitory effect on the mitochondrial cytochrome c oxidase (COX) as well as the conditions for its recovery have not yet been fully explained. We investigated three parameters
of COX function, namely electron transport (oxygen consumption), proton transport (mitochondrial membrane potential Δψ
m) and the enzyme affinity to oxygen (p
50
value) with regard to the inhibition by KCN and its reversal by pyruvate. 250 μM KCN completely inhibited both the electron
and proton transport function of COX. The inhibition was reversible as demonstrated by washing of mitochondria. The addition
of 60 mM pyruvate induced the maximal recovery of both parameters to 60–80% of the original values. When using low KCN concentrations
of up to 5 μM, we observed a profound, 30-fold decrease of COX affinity for oxygen. Again, this decrease was completely reversed
by washing mitochondria while pyruvate induced only a partial, yet significant recovery of oxygen affinity. Our results demonstrate
that the inhibition of COX by cyanide is reversible and that the potential of pyruvate as a cyanide poisoning antidote is
limited. Importantly, we also showed that the COX affinity for oxygen is the most sensitive indicator of cyanide toxic effects. 相似文献