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Journal articles on the topic 'Oxygen mismatch'

Author: Grafiati
Published: 28 September 2022
Last updated: 28 January 2023

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1

Detterich, Jon A., Roberta Kato, Adam Bush, Patjanaporn Chalacheva, Derek Ponce, Madushka De Zoysa, Payal Shah, et al. "Sickle cell microvascular paradox—oxygen supply‐demand mismatch." American Journal of Hematology 94, no. 6 (April 19, 2019): 678–88. http://dx.doi.org/10.1002/ajh.25476.

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2

Petersson, Johan, and Robb W. Glenny. "Gas exchange and ventilation–perfusion relationships in the lung." European Respiratory Journal 44, no. 4 (July 25, 2014): 1023–41. http://dx.doi.org/10.1183/09031936.00037014.

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This review provides an overview of the relationship between ventilation/perfusion ratios and gas exchange in the lung, emphasising basic concepts and relating them to clinical scenarios. For each gas exchanging unit, the alveolar and effluent blood partial pressures of oxygen and carbon dioxide (PO2andPCO2) are determined by the ratio of alveolar ventilation to blood flow (V′A/Q′) for each unit. Shunt and lowV′A/Q′ regions are two examples ofV′A/Q′ mismatch and are the most frequent causes of hypoxaemia. Diffusion limitation, hypoventilation and low inspiredPO2cause hypoxaemia, even in the absence ofV′A/Q′ mismatch. In contrast to other causes, hypoxaemia due to shunt responds poorly to supplemental oxygen. Gas exchanging units with little or no blood flow (highV′A/Q′ regions) result in alveolar dead space and increased wasted ventilation,i.e.less efficient carbon dioxide removal. Because of the respiratory drive to maintain a normal arterialPCO2, the most frequent result of wasted ventilation is increased minute ventilation and work of breathing, not hypercapnia. Calculations of alveolar–arterial oxygen tension difference, venous admixture and wasted ventilation provide quantitative estimates of the effect ofV′A/Q′ mismatch on gas exchange. The types ofV′A/Q′ mismatch causing impaired gas exchange vary characteristically with different lung diseases.
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3

Guo, Er-Jia, Yaohua Liu, Changhee Sohn, Ryan D. Desautels, Andreas Herklotz, Zhaoliang Liao, John Nichols, John W. Freeland, Michael R. Fitzsimmons, and Ho Nyung Lee. "Oxygen Diode Formed in Nickelate Heterostructures by Chemical Potential Mismatch." Advanced Materials 30, no. 15 (March 7, 2018): 1705904. http://dx.doi.org/10.1002/adma.201705904.

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4

Niu, Guangda, Siyu Wang, Jiangwei Li, Wenzhe Li, and Liduo Wang. "Oxygen doping in nickel oxide for highly efficient planar perovskite solar cells." Journal of Materials Chemistry A 6, no. 11 (2018): 4721–28. http://dx.doi.org/10.1039/c8ta00161h.

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5

Fernández Sanjulián, Javier, Madhu Chennabasappa, Susana García-Martín, Gwilherm Nénert, Alain Wattiaux, Etienne Gaudin, and Olivier Toulemonde. "Oxygen vacancy ordering in SrFe0.25Co0.75O2.63 perovskite material." Dalton Transactions 46, no. 5 (2017): 1624–33. http://dx.doi.org/10.1039/c6dt03927h.

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An oxygen-vacancy ordering related to the “314” model known for the Sr3Y1Co4O10.5 oxide is proposed for Sr4FeCo3O10.52 material despite there is neither A-site ordering nor A-site mismatch.
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6

Yuzawa, Izumi, Sava Sakadžić, Vivek J. Srinivasan, Hwa Kyoung Shin, Katharina Eikermann-Haerter, David A. Boas, and Cenk Ayata. "Cortical Spreading Depression Impairs Oxygen Delivery and Metabolism in Mice." Journal of Cerebral Blood Flow & Metabolism 32, no. 2 (October 19, 2011): 376–86. http://dx.doi.org/10.1038/jcbfm.2011.148.

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Cortical spreading depression (CSD) is associated with severe hypoperfusion in mice. Using minimally invasive multimodal optical imaging, we show that severe flow reductions during and after spreading depression are associated with a steep decline in cerebral metabolic rate of oxygen. Concurrent severe hemoglobin desaturation suggests that the oxygen metabolism becomes at least in part supply limited, and the decrease in cortical blood volume implicates vasoconstriction as the mechanism. In support of oxygen supply-demand mismatch, cortical nicotinamide adenine dinucleotide (NADH) fluorescence increases during spreading depression for at least 5 minutes, particularly away from parenchymal arterioles. However, modeling of tissue oxygen delivery shows that cerebral metabolic rate of oxygen drops more than predicted by a purely supply-limited model, raising the possibility of a concurrent reduction in oxygen demand during spreading depression. Importantly, a subsequent spreading depression triggered within 15 minutes evokes a monophasic flow increase superimposed on the oligemic baseline, which markedly differs from the response to the preceding spreading depression triggered in naive cortex. Altogether, these data suggest that CSD is associated with long-lasting oxygen supply-demand mismatch linked to severe vasoconstriction in mice.
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7

Fujii, Miki, Chieri Hata, Munetada Ukita, Chie Fukushima, Chihiro Matsuura, Yoshie Kawashima-Ohya, Koji Tomobe, and Tsuyoshi Kawashima. "Characterization of a Thermostable 8-Oxoguanine DNA Glycosylase Specific for GO/N Mismatches from the Thermoacidophilic ArchaeonThermoplasma volcanium." Archaea 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/8734894.

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The oxidation of guanine (G) to 7,8-dihydro-8-oxoguanine (GO) forms one of the major DNA lesions generated by reactive oxygen species (ROS). The GO can be corrected by GO DNA glycosylases (Ogg), enzymes involved in base excision repair (BER). Unrepaired GO induces mismatched base pairing with adenine (A); as a result, the mismatch causes a point mutation, from G paired with cytosine (C) to thymine (T) paired with adenine (A), during DNA replication. Here, we report the characterization of a putative Ogg from the thermoacidophilic archaeonThermoplasma volcanium. The 204-amino acid sequence of the putative Ogg (TVG_RS00315) shares significant sequence homology with the DNA glycosylases ofMethanocaldococcus jannaschii(MjaOgg) andSulfolobus solfataricus(SsoOgg). The six histidine-tagged recombinant TVG_RS00315 protein gene was expressed inEscherichia coliand purified. The Ogg protein is thermostable, with optimal activity near a pH of 7.5 and a temperature of 60°C. The enzyme displays DNA glycosylase, and apurinic/apyrimidinic (AP) lyase activities on GO/N (where N is A, T, G, or C) mismatch; yet it cannot eliminate U from U/G or T from T/G, as mismatch glycosylase (MIG) can. These results indicate that TvoOgg-encodingTVG_RS00315is a member of the Ogg2 family ofT. volcanium.
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8

Li, Xiang, Yaming Liu, Wei Bi, Jinglei Bi, Ruiyun Guo, Rui Li, Chaoqi Wang, et al. "Lattice-mismatch-induced growth of ultrathin Pt shells with high-index facets for boosting oxygen reduction catalysis." Journal of Materials Chemistry A 8, no. 32 (2020): 16477–86. http://dx.doi.org/10.1039/d0ta05410k.

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9

Shen, Qiang, Shiliang Huang, and Timothy Q. Duong. "T2*-weighted fMRI time-to-peak of oxygen challenge in ischemic stroke." Journal of Cerebral Blood Flow & Metabolism 36, no. 2 (October 6, 2015): 283–91. http://dx.doi.org/10.1177/0271678x15606461.

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T2*-weighted MRI of transient oxygen challenge (OC) showed exaggerated OC percent changes in the ischemic tissue at risk compared to normal tissue. One ambiguity is that regions with high vascular density also showed exaggerated OC percent changes. This study explored time-to-peak (TTP) of the OC percent changes to improve the utility of T2*-weighted OC MRI. Experiments were performed longitudinally at 30 min, 150 min and 24 h after transient (60-min) stroke in rats. Ischemic core, normal, and mismatch tissue were classified pixel-by-pixel based on apparent diffusion coefficient and cerebral blood flow. Major findings were: (i) Delayed OC TTP was localized to and corresponded well with the perfusion-diffusion mismatch. (ii) By contrast, the exaggerated OC percent changes were less localized, with changes not only in the at-risk tissue but also in some areas of the contralesional hemisphere with venous vessel origins. (iii) The OC time-course of the mismatch tissue was biphasic, with a faster initial increase followed by a slower increase. (iv) At-risk tissue with delayed TTP and exaggerated OC was normal after reperfusion and the at-risk tissue was mostly (83 ± 18%) rescued by reperfusion as indicated by normal 24-h T2. OC TTP offers unique information toward better characterization of at-risk tissue in ischemic stroke.
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10

Shen, Weida, and Joshua L. Hertz. "Ionic conductivity of YSZ/CZO multilayers with variable lattice mismatch." Journal of Materials Chemistry A 3, no. 5 (2015): 2378–86. http://dx.doi.org/10.1039/c4ta03892d.

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11

Little, Philip V., Sandra E. Kraft, Arvin Chireh, Peter Damberg, and Staffan Holmin. "Oxygen metabolism MRI – A comparison with perfusion imaging in a rat model of MCA branch occlusion and reperfusion." Journal of Cerebral Blood Flow & Metabolism 40, no. 11 (December 16, 2019): 2315–27. http://dx.doi.org/10.1177/0271678x19892271.

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The penumbra is sustained by an increased extraction of oxygen (OEF) from blood to brain tissue. Metabolic imaging may improve penumbra specificity when examining stroke patients with wake-up stroke and a long time between admission and symptom onset. We used MRI to examine OEF, and compared the volume of regions with elevated OEF to the volume of regions with perfusion deficit in a M2 occlusion model (M2CAO) with preserved collateral blood flow. OEF was calculated from BOLD MRI examining tissue R2′, with ASL perfusion imaging employed to determine cerebral blood flows (CBF) and volumes. Diffusion imaging was used to identify the ischemic core (IC). Examinations were performed during and after transient M2CAO in rats. The IC-OEF mismatch was significantly smaller than the IC-CBF mismatch during M2CAO. The penumbra OEF was significantly increased during M2CAO, and decreased significantly after reperfusion. The IC-OEF mismatch may provide increased penumbra specificity compared to IC-CBF mismatch regimens. Results strongly indicate the potential of metabolic MRI for thrombectomy patient selection in cases with a long time from symptom onset to admission. Results demonstrate the effectiveness of reperfusion in alleviating metabolic disturbances in ischemic regions, emphasizing fast treatment to achieve significant neurological recovery in stroke patients.
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12

Lorenzano, Svetlana, Natalia S. Rost, Muhib Khan, Hua Li, Leonardo M. Batista, Aurauma Chutinet, Rebecca E. Green, et al. "Early molecular oxidative stress biomarkers of ischemic penumbra in acute stroke." Neurology 93, no. 13 (August 27, 2019): e1288-e1298. http://dx.doi.org/10.1212/wnl.0000000000008158.

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ObjectivesTo assess whether plasma biomarkers of oxidative stress predict diffusion-perfusion mismatch in patients with acute ischemic stroke (AIS).MethodsWe measured plasma levels of oxidative stress biomarkers such as F2-isoprostanes (F2-isoPs), total and perchloric acid Oxygen Radical Absorbance Capacity (ORACTOT and ORACPCA), urinary levels of 8-oxo-7,8-dihydro-2′-deoxyguoanosine, and inflammatory and tissue-damage biomarkers (high-sensitivity C-reactive protein, matrix metalloproteinase-2 and -9) in a prospective study of patients with AIS presenting within 9 hours of symptom onset. Diffusion-weighted (DWI) and perfusion-weighted (PWI) MRI sequences were analyzed with a semiautomated volumetric method. Mismatch was defined as baseline mean transit time volume minus DWI volume. A percent mismatch cutoff of >20% was considered clinically significant. A stricter definition of mismatch was also used. Mismatch salvage was the region free of overlap by final infarction.ResultsMismatch >20% was present in 153 of 216 (70.8%) patients (mean [±SD] age 69.2 ± 14.3 years, 41.2% women). Patients with mismatch >20% were more likely to have higher baseline plasma levels of ORACPCA (p = 0.020) and F2-isoPs (p = 0.145). Multivariate binary logistic regression demonstrated that lnF2-isoP (odds ratio [OR] 2.44, 95% confidence interval [CI] 1.19–4.98, p = 0.014) and lnORACPCA (OR 4.18, 95% CI 1.41–12.41, p = 0.010) were independent predictors of >20% PWI-DWI mismatch and the stricter mismatch definition, respectively. lnORACTOT significantly predicted mismatch salvage volume (>20% mismatch p = 0.010, stricter mismatch definition p = 0.003).ConclusionsElevated hyperacute plasma levels of F2-isoP and ORAC are associated with radiographic evidence of mismatch and mismatch salvage in patients with AIS. If validated, these findings may add to our understanding of the role of oxidative stress in cerebral tissue fate during acute ischemia.
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13

Amann, K., M. Breitbach, E. Ritz, and G. Mall. "Myocyte/capillary mismatch in the heart of uremic patients." Journal of the American Society of Nephrology 9, no. 6 (June 1998): 1018–22. http://dx.doi.org/10.1681/asn.v961018.

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Experiments indicate that capillary density is reduced in the hypertrophied left ventricle of rats with subtotal nephrectomy compared to control rats with similar BP and left ventricular hypertrophy, suggesting that in uremia, hypertrophying cardiomyocytes outgrow their capillary supply. No information on myocardial capillary supply in humans is currently available. The hearts of nine dialyzed patients, nine patients with essential hypertension, and 10 normotensive control subjects at postmortem were obtained. Subjects with stenosing coronary lesions and left ventricular pump failure were excluded. Special sampling procedures were used to exclude stereologic artefacts. Capillaries were specifically stained with ulex lectin and analyzed by stereologic techniques. Length density of myocardial capillaries (Lv; mm/mm3) was significantly (P < 0.001) lower in dialyzed patients (1483 +/- 238) than in patients with essential hypertension (1872 +/- 243) or in normotensive control patients (2898 +/- 456). In parallel, myocyte diameter and volume density of myocardial interstitial tissue were significantly (P < 0.001) increased in uremic patients compared to patients with essential hypertension and control patients, respectively. Diminished left ventricular capillary supply in renal failure must increase critical oxygen diffusion distance in the myocardium, thus exposing cardiomyocytes to the risk of hypoxia. It is unknown whether such reduced ischemia tolerance can be reversed by increasing oxygen supply (e.g., by reversing anemia).
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14

Kim, Young-Hoon, Sunyang Kim, Ki-jeong Kim, Chaeyoung Kim, Jae Hyuck Jang, Young-Min Kim, and Hangil Lee. "Multiscale probing of the influence of the defect-induced variation of oxygen vacancies on the photocatalytic activity of doped ZnO nanoparticles." Journal of Materials Chemistry A 8, no. 47 (2020): 25345–54. http://dx.doi.org/10.1039/d0ta08367d.

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Oxygen vacancies on the photocatalytic activity can alter the local charge states of neighboring cations. This work highlights multimodal and multiscale spectroscopic probing of the significant role of charge mismatch by the doped cation.
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15

Mayor, Nikhil, Harry Knights, Aleksandra Kotwica, Andrew Solomon Joseph Coppola, Harriet Hunter, Nathan Jeffreys, Alexander Morgan, et al. "Intrapulmonary shunting is a key contributor to hypoxia in COVID-19: An update on the pathophysiology." PLOS ONE 17, no. 10 (October 20, 2022): e0273402. http://dx.doi.org/10.1371/journal.pone.0273402.

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Background The pathophysiology of COVID-19 remains poorly understood. We aimed to estimate the contribution of intrapulmonary shunting and ventilation-to-perfusion (VA/Q) mismatch using a mathematical model to construct oxygen-haemoglobin dissociation curves (ODCs). Methods ODCs were constructed using transcutaneous pulse oximetry at two different fractions of inspired oxygen (FiO2). 199 patients were included from two large district general hospitals in the South East of England from 1st to 14th January 2021. The study was supported by the National Institute of Health Research (NIHR) Clinical Research Network. Results Overall mortality was 29%. Mean age was 68.2 years (SEM 1·2) with 46% female. Median shunt on admission was 17% (IQR 8–24.5); VA/Q was 0.61 (IQR 0.52–0.73). Shunt was 37.5% higher in deaths (median 22%, IQR 9–29) compared to survivors (16%, 8–21; p = 0.0088) and was a predictor of mortality (OR 1.04; 95% CI 1.01–1.07). Admission oxygen saturations were more strongly predictive of mortality (OR 0.91, 95% CI 0.87–0.96). There was no difference in VA/Q mismatch between deaths (0.60; IQR 0.50–0.73) and survivors (0.61; IQR 0.52–0.73; p = 0.63) and it was not predictive of mortality (OR 0.68; 95% CI 0.18–2.52; p = 0.55). Shunt negatively correlated with admission oxygen saturation (R -0.533; p<0.0001) whereas VA/Q was not (R 0.1137; p = 0.12). Interpretation Shunt, not VA/Q mismatch, was associated with worsening hypoxia, though calculating shunt was not of prognostic value. This study adds to our understanding of the pathophysiology of hypoxaemia in COVID-19. Our inexpensive and reliable technique may provide further insights into the pathophysiology of hypoxia in other respiratory diseases.
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16

Oja, Joni M. E., Joseph S. Gillen, Risto A. Kauppinen, Michael Kraut, and Peter C. M. van Zijl. "Determination of Oxygen Extraction Ratios by Magnetic Resonance Imaging." Journal of Cerebral Blood Flow & Metabolism 19, no. 12 (December 1999): 1289–95. http://dx.doi.org/10.1097/00004647-199912000-00001.

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The oxygen extraction ratio (OER) of a tissue describes the interplay between oxygen delivery and consumption and, as such, directly reflects the viability and activity of any organ. It is shown that OER can be quantified using a single magnetic resonance imaging observable, namely the relaxation time T2 of venous blood draining from the tissue. This principle is applied to study local OER changes in the brain on visual stimulation in humans, unambiguously demonstrating a mismatch between changes in blood flow and oxygen metabolism on activation.
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17

Gao, Y., and S. A. Chambers. "Effect of substrate orientation on the crystal quality and surface roughness of Nb-doped TiO2 epitaxial films on TiO2." Journal of Materials Research 11, no. 4 (April 1996): 1025–29. http://dx.doi.org/10.1557/jmr.1996.0128.

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We have grown Nb-doped TiO2 epitaxial films on (100) and (110)-oriented TiO2 rutile substrates by molecular beam epitaxy. Nb substitutionally incorporates at cation sites in the rutile lattice, forming NbxTi1−xO2 solid solutions. However, the crystal quality and surface roughness of the films depend strongly on the substrate orientation. Surface roughening and defect formation occur at lower values of x on (100) than on (110). This result is due to anisotropic changes in the metal-oxygen bond lengths within the rutile structure in going from TiO2 to NbO2; there are 1% and 12% changes in the metal atom to octahedron-base oxygen and metal atom to octahedron-vertex oxygen bond lengths, respectively. Every metal atom in the (100) growth surface has in-plane components of the 12% mismatch. However, only half of the metal atoms in the (110) growth plane have such components. Thus, there is substantially larger in-plane lattice mismatch when the growth surface is (100) compared to (110), resulting in surface roughening and formation of defects at a lower doping level for (100)-oriented NbxTi1−xO2 epitaxial films.
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18

Medeiros, Wladimir M., Mari C. T. Fernandes, Diogo P. Azevedo, Flavia F. M. de Freitas, Beatriz C. Amorim, Luciana D. Chiavegato, Daniel M. Hirai, Denis E. O'Donnell, and J. Alberto Neder. "Oxygen delivery-utilization mismatch in contracting locomotor muscle in COPD: peripheral factors." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 308, no. 2 (January 15, 2015): R105—R111. http://dx.doi.org/10.1152/ajpregu.00404.2014.

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Central cardiorespiratory and gas exchange limitations imposed by chronic obstructive pulmonary disease (COPD) impair ambulatory skeletal muscle oxygenation during whole body exercise. This investigation tested the hypothesis that peripheral factors per se contribute to impaired contracting lower limb muscle oxygenation in COPD patients. Submaximal neuromuscular electrical stimulation (NMES; 30, 40, and 50 mA at 50 Hz) of the quadriceps femoris was employed to evaluate contracting skeletal muscle oxygenation while minimizing the influence of COPD-related central cardiorespiratory constraints. Fractional O2 extraction was estimated by near-infrared spectroscopy (deoxyhemoglobin/myoglobin concentration; deoxy-[Hb/Mb]), and torque output was measured by isokinetic dynamometry in 15 nonhypoxemic patients with moderate-to-severe COPD (SpO2 = 94 ± 2%; FEV1 = 46.4 ± 10.1%; GOLD II and III) and in 10 age- and gender-matched sedentary controls. COPD patients had lower leg muscle mass than controls (LMM = 8.0 ± 0.7 kg vs. 8.9 ± 1.0 kg, respectively; P < 0.05) and produced relatively lower absolute and LMM-normalized torque across the range of NMES intensities ( P < 0.05 for all). Despite producing less torque, COPD patients had similar deoxy-[Hb/Mb] amplitudes at 30 and 40 mA ( P > 0.05 for both) and higher deoxy-[Hb/Mb] amplitude at 50 mA ( P < 0.05). Further analysis indicated that COPD patients required greater fractional O2 extraction to produce torque (i.e., ↑Δdeoxy-[Hb/Mb]/torque) relative to controls ( P < 0.05 for 40 and 50 mA) and as a function of NMES intensity ( P < 0.05 for all). The present data obtained during submaximal NMES of small muscle mass indicate that peripheral abnormalities contribute mechanistically to impaired contracting skeletal muscle oxygenation in nonhypoxemic, moderate-to-severe COPD patients.
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19

Gaffurini, Paolo, Caterina Neviani, Claudio Orizio, and Massimiliano Gobbo. "Oxygen supply/uptake mismatch during incremental stimulation of the human tibialis anterior." Sport Sciences for Health 7, no. 2-3 (May 2012): 65–70. http://dx.doi.org/10.1007/s11332-012-0114-9.

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20

Francis, Michael F. "Colossal Ionic Conductivity:Method of Measuring the Elastic Dipole of Charged States& a Reduced Model for the Screening of Heterolayer Structures." ECS Meeting Abstracts MA2018-01, no. 32 (April 13, 2018): 1932. http://dx.doi.org/10.1149/ma2018-01/32/1932.

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Colossal Ionic Conductivity, the fast diffusion of oxygen ions in heterolayer environments, has promised to provide oxygen migration rates fast enough for low temperature solid oxide fuel cells. These promises have stirred great debate, but despite ongoing discussion, the physics controlling Colossal Ionic Conductivity remains poorly understood. Hypotheses offered have been mechanical effects, phase changes, sublattice melting, interfacial effects, and space charge effects, though none tested. Here, a method of calculating the elastic dipole of charged states is shown, which will enable the testing of the mechanical hypothesis. Whichever physics are controlling, observed changes in conductivity have been shown to correlate with heterolayer material lattice mismatch. This lattice mismatch can be shown to be the result of strain dependent properties. Here, a reduced model of heterolayer structure and strain allowing the rapid screening of a large number of structures for the optimization of the conducting interface.
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21

Latfullin, I. A. "Myocardial infarction (clinic, diagnostic features, complications, treatment)." Kazan medical journal 78, no. 2 (April 15, 1997): 120–28. http://dx.doi.org/10.17816/kazmj81374.

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Myocardial infarction (MI) occurs due to an acute mismatch between myocardial oxygen demand and its blood supply through the coronary arteries of the heart, which results in the development of ischemic necrosis of the heart muscle with subsequent topical changes on ECG.
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22

Thomas, Joanna L., Hai Pham, Ying Li, Elanore Hall, Guy A. Perkins, Sameh S. Ali, Hemal H. Patel, and Prabhleen Singh. "Hypoxia-inducible factor-1α activation improves renal oxygenation and mitochondrial function in early chronic kidney disease." American Journal of Physiology-Renal Physiology 313, no. 2 (August 1, 2017): F282—F290. http://dx.doi.org/10.1152/ajprenal.00579.2016.

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The pathophysiology of chronic kidney disease (CKD) is driven by alterations in surviving nephrons to sustain renal function with ongoing nephron loss. Oxygen supply-demand mismatch, due to hemodynamic adaptations, with resultant hypoxia, plays an important role in the pathophysiology in early CKD. We sought to investigate the underlying mechanisms of this mismatch. We utilized the subtotal nephrectomy (STN) model of CKD to investigate the alterations in renal oxygenation linked to sodium (Na) transport and mitochondrial function in the surviving nephrons. Oxygen delivery was significantly reduced in STN kidneys because of lower renal blood flow. Fractional oxygen extraction was significantly higher in STN. Tubular Na reabsorption was significantly lower per mole of oxygen consumed in STN. We hypothesized that decreased mitochondrial bioenergetic capacity may account for this and uncovered significant mitochondrial dysfunction in the early STN kidney: higher oxidative metabolism without an attendant increase in ATP levels, elevated superoxide levels, and alterations in mitochondrial morphology. We further investigated the effect of activation of hypoxia-inducible factor-1α (HIF-1α), a master regulator of cellular hypoxia response. We observed significant improvement in renal blood flow, glomerular filtration rate, and tubular Na reabsorption per mole of oxygen consumed with HIF-1α activation. Importantly, HIF-1α activation significantly lowered mitochondrial oxygen consumption and superoxide production and increased mitochondrial volume density. In conclusion, we report significant impairment of renal oxygenation and mitochondrial function at the early stages of CKD and demonstrate the beneficial role of HIF-1α activation on renal function and metabolism.
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23

Walley, K. R. "Heterogeneity of oxygen delivery impairs oxygen extraction by peripheral tissues: theory." Journal of Applied Physiology 81, no. 2 (August 1, 1996): 885–94. http://dx.doi.org/10.1152/jappl.1996.81.2.885.

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The hypothesis that the distribution of oxygen demand in relation to oxygen supply (dO2/qO2) effects oxygen extraction in peripheral tissues was tested. By using a simple theoretical model, realistic biphasic oxygen consumption-delivery relationships were predicted from dO2/qO2 distributions. Increasing width (relative dispersion) of the dO2/qO2 distribution, indicating mismatch between oxygen demand and supply, nonlinearly decreased the critical oxygen extraction ratio (calculated by using dual-line regression). Skewed dO2/qO2 distributions had a lesser effect. Incomplete oxygen uptake, due to diffusion limitation or other causes of physiological arteriovenous shunt, linearly decreased the critical oxygen extraction ratio. Approximate dO2/qO2 distributions were then estimated from previously reported capillary transit-time distributions. Critical oxygen extraction ratios predicted from these estimated dO2/qO2 distributions match reported values. This theoretical approach also predicts the decrease in the critical oxygen extraction ratio in porcine gut after endotoxin infusion in the companion paper (M. F. Humer, P. T. Phang, B. P. Friesen, M. F. Allard, C. M. Goddard, and K. R. Walley. J. Appl. Physiol. 81: 895–904, 1996). Much as pulmonary ventilation-perfusion relationships account for pulmonary gas exchange, dO2/qO2 distributions quantitatively account for measured tissue oxygen extraction and predict novel features of the relationship between heterogeneity and oxygen extraction.
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24

Clark, Justin S., Yuxiang J. Lin, Michael J. Criddle, Antonio G. Cutillo, Adelbert H. Bigler, Fred L. Farr, and Attilio D. Renzetti. "Cardiac output and mixed venous oxygen content measurements by a tracer bolus method: theory." Journal of Applied Physiology 83, no. 3 (September 1, 1997): 884–96. http://dx.doi.org/10.1152/jappl.1997.83.3.884.

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Clark, Justin S., Yuxiang J. Lin, Michael J. Criddle, Antonio G. Cutillo, Adelbert H. Bigler, Fred L. Farr, and Attilio D. Renzetti, Jr. Cardiac output and mixed venous oxygen content measurements by a tracer bolus method: theory. J. Appl. Physiol. 83(3): 884–896, 1997.—We present a bolus method of inert-gas delivery to the lungs that facilitates application of multiple inert gases and the multiple inert-gas-exchange technique (MIGET) model to noninvasive measurements of cardiac output (CO) and central mixed venous oxygen content[Formula: see text]Reduction in recirculation error is made possible by 1) replacement of sinusoidal input functions with impulse inputs and 2) replacement of steady-state analyses with transient analyses. Recirculation error reduction increases the inert-gas selection to include common gases without unusually high (and difficult to find) tissue-to-blood partition coefficients for maximizing the systemic filtering efficiency. This paper also presents a practical method for determining the recirculation contributions to inert expired profiles in animals and determining their specific contributions to errors in the calculations of CO and[Formula: see text] from simulations applied to published ventilation-perfusion ratio (V˙/Q˙) profiles. Recirculation errors from common gases were found to be reducible to the order of 5% or less for both CO and[Formula: see text] whereas simulation studies indicate that measurement bias contributions from recirculation, V˙/Q˙ mismatch, and the V˙/Q˙ extraction process can be limited to 15% for subjects with severeV˙/Q˙ mismatch and high inspired oxygen fraction levels. These studies demonstrate a decreasing influence of V˙/Q˙ mismatch on parameter extraction bias as the number of inert gases are increased. However, the influence of measurement uncertainty on parameter extraction error limits improvement to six gases.
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Khor, Yet H., Nicole S. L. Goh, Christine F. McDonald, and Anne E. Holland. "Oxygen Therapy for Interstitial Lung Disease. A Mismatch between Patient Expectations and Experiences." Annals of the American Thoracic Society 14, no. 6 (June 2017): 888–95. http://dx.doi.org/10.1513/annalsats.201611-934oc.

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26

Gazquez, J., Shameek Bose, M. Sharma, M. A. Torija, S. J. Pennycook, C. Leighton, and M. Varela. "Lattice mismatch accommodation via oxygen vacancy ordering in epitaxial La0.5Sr0.5CoO3-δ thin films." APL Materials 1, no. 1 (July 2013): 012105. http://dx.doi.org/10.1063/1.4809547.

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27

Blacker, Kara J., Todd R. Seech, Matthew E. Funke, and Micah J. Kinney. "Deficits in Visual Processing During Hypoxia as Evidenced by Visual Mismatch Negativity." Aerospace Medicine and Human Performance 92, no. 5 (May 1, 2021): 326–32. http://dx.doi.org/10.3357/amhp.5735.2021.

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INTRODUCTION: Hypoxia is an ever-present threat in tactical aviation and gained recent attention due to its putative role in physiological episodes. Previous work has demonstrated that hypoxia negatively impacts a variety of sensory, cognitive, and motor systems. In particular, the visual system is one of the earliest systems affected by hypoxia. While the majority of previous studies have relied on self-report and behavioral testing, the use of event-related potentials as a novel tool to monitor responses to low oxygen in humans has recently been investigated. Specifically, ERP components that are evoked passively in response to unattended changes in background sensory stimulation have been explored.METHOD: Subjects (N 28) completed a continuous visuomotor tracking task while EEG was recorded. During the tracking task, a series of standard color checkerboard patterns were presented in the periphery while occasionally a deviant color checkerboard was presented. The visual mismatch negativity (MMN) component was assessed in response to the deviant compared to the standard stimuli. Subjects completed two sessions in counterbalanced order that only differed by the oxygen concentration breathed (10.6% vs. 20.4%).RESULTS: Results demonstrated a significant reduction in the amplitude of the visual MMN under hypoxic compared to normoxic conditions, showing a 50% reduction in amplitude during hypoxia. Our results suggest that during low-oxygen exposure the ability to detect environmental changes and process sensory information is impaired.DISCUSSION: The visual MMN may represent an early and reliable predictor of sensory and cognitive deficits during hypoxia exposure, which may be of great use to the aviation community.Blacker KJ, Seech TR, Funke ME, Kinney MJ. Deficits in visual processing during hypoxia as evidenced by visual mismatch negativity. Aerosp Med Hum Perform. 2021; 92(5):326332.
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Williams, Joshua R., Chongmin Wang, and Scott A. Chambers. "Heteroepitaxial growth and structural analysis of epitaxial α–Fe2O3(1010) on TiO2(001)." Journal of Materials Research 20, no. 5 (May 2005): 1250–56. http://dx.doi.org/10.1557/jmr.2005.0164.

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We grew epitaxial α–Fe2O3(1010) on TiO2(001) rutile by oxygen plasma-assisted molecular-beam epitaxy. High-resolution transmission electron microscopy (HRTEM), reflection high-energy electron diffraction (RHEED), and x-ray diffraction pole figures confirm that the film is composed of four different in-plane orientations rotated by 90° relative to one another. For a given Fe2O3 unit cell, the lattice mismatch along the parallel [0001]Fe2O3 and [100]TiO2 directions is nominally +67%. However, due to a 3-fold repetition of the slightly distorted square symmetry of anion positions within the Fe2O3 unit cell, there is a coincidental anion alignment along the [0001]Fe2O3 and [100]TiO2 directions, which results in an effective lattice mismatch of only −0.02% along this direction. The lattice mismatch is nearly 10% in the orthogonal [1120]Fe2O3 and [100]TiO2 directions. The film is highly ordered and well registered to the substrate despite a large lattice mismatch in one direction. The film grows in registry with the substrate along the parallel [0001]Fe2O3 and [100]TiO2 directions and nucleates dislocations along the orthogonal [1120]Fe2O3 [100]TiO2 directions.
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Kong, Bo Hyun, and Hyung Koun Cho. "Growth and microstructural characterization of catalyst-free ZnO nanostructures grown on sapphire and GaN by thermal evaporation." Journal of Materials Research 22, no. 4 (April 2007): 937–42. http://dx.doi.org/10.1557/jmr.2007.0108.

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ZnO nanostructures were grown directly on sapphire substrates and GaN epilayers by thermal evaporation. Their morphologies and densities were found to be strongly dependent on the synthesis position and the kinds of substrate loaded into the reactor due to the different oxygen densities and the lattice mismatch, respectively. Scanning electron microscopy and transmission electron microscopy studies revealed that ZnO nanorods on sapphire substrates grew in four directions, one 〈0001〉Sapphire and three (1014)Sapphire directions. It was found that the in-plane lattice mismatch of inclined ZnO nanorods was remarkably reduced by forming the planar relationship of (0002)ZnO//(1014)Sapphire, compared to that of (1120)ZnO//(1010)Sapphire in the ZnO film. On the other hand, for the GaN epilayers, vertically well-aligned ZnO nanorods were grown after growing an epitaxial ZnO film due to reduced lattice mismatch. Electron energy-loss spectroscopy data showed that Zn-rich stoichiometry was responsible for the formation of ZnO nanostructures.
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30

Vafaee, Manouchehr S., Kim Vang, Linda H. Bergersen, and Albert Gjedde. "Oxygen Consumption and Blood Flow Coupling in Human Motor Cortex during Intense Finger Tapping: Implication for a Role of Lactate." Journal of Cerebral Blood Flow & Metabolism 32, no. 10 (July 11, 2012): 1859–68. http://dx.doi.org/10.1038/jcbfm.2012.89.

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Rates of cerebral blood flow (CBF) and glucose consumption (CMRglc) rise in cerebral cortex during continuous stimulation, while the oxygen-glucose index (OGI) declines as an index of mismatched coupling of oxygen consumption (cerebral metabolic rate of oxygen—CMRO2) to CBF and CMRglc. To test whether the mismatch reflects a specific role of aerobic glycolysis during functional brain activation, we determined CBF and CMRO2 with positron emission tomography (PET) when 12 healthy volunteers executed finger-to-thumb apposition of the right hand. Movements began 1, 10, or 20 minutes before administration of the radiotracers. In primary and supplementary motor cortices and cerebellum, CBF had increased at 1 minute of exercise and remained elevated for the duration of the 20-minute session. In contrast, the CMRO2 numerically had increased insignificantly in left M1 and supplementary motor area at 1 minute, but had declined significantly at 10 minutes, returning to baseline at 20 minutes. As measures of CMRglc are impossible during short-term activations, we used measurements of CBF as indices of CMRglc. The decline of CMRO2 at 10 minutes paralleled a calculated decrease of OGI at this time. The implied generation of lactate in the tissue suggested an important hypothetical role of the metabolite as regulator of CBF during activation.
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Song, Jiang-Ling, Jennifer A. Kim, Aaron F. Struck, Rui Zhang, and M. Brandon Westover. "A model of metabolic supply-demand mismatch leading to secondary brain injury." Journal of Neurophysiology 126, no. 2 (August 1, 2021): 653–67. http://dx.doi.org/10.1152/jn.00674.2020.

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We present a novel mechanistic model for the metabolic supply demand mismatch hypothesis (MSDMH), which attempts to explain why patients with acute brain injury frequently develop seizure activity and secondary brain injury (SBI). Specifically, we investigate how decreased oxygen, increased extracellular potassium, excitotoxicity, seizures, all common sequalae of primary brain injury (PBI), can induce SBI and suggest three underlying paths for how events following PBI may lead to SBI.
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32

Wheaton, William W., and Navdeep S. Chandel. "Hypoxia. 2. Hypoxia regulates cellular metabolism." American Journal of Physiology-Cell Physiology 300, no. 3 (March 2011): C385—C393. http://dx.doi.org/10.1152/ajpcell.00485.2010.

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Adaptation to lowering oxygen levels (hypoxia) requires coordinated downregulation of metabolic demand and supply to prevent a mismatch in ATP utilization and production that might culminate in a bioenergetic collapse. Hypoxia diminishes ATP utilization by downregulating protein translation and the activity of the Na-K-ATPase. Hypoxia diminishes ATP production in part by lowering the activity of the electron transport chain through activation of the transcription factor hypoxia-inducible factor-1. The decrease in electron transport limits the overproduction of reactove oxygen species during hypoxia and slows the rate of oxygen depletion to prevent anoxia. In this review, we discuss these mechanisms that diminish metabolic supply and demand for adaptation to hypoxia.
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Corradi, Francesco, Claudia Brusasco, Francesco Paparo, Tullio Manca, Gregorio Santori, Filippo Benassi, Alberto Molardi, et al. "Renal Doppler Resistive Index as a Marker of Oxygen Supply and Demand Mismatch in Postoperative Cardiac Surgery Patients." BioMed Research International 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/763940.

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Background and Objective. Renal Doppler resistive index (RDRI) is a noninvasive index considered to reflect renal vascular perfusion. The aim of this study was to identify the independent hemodynamic determinants of RDRI in mechanically ventilated patients after cardiac surgery.Methods. RDRI was determined in 61 patients by color and pulse Doppler ultrasonography of the interlobar renal arteries. Intermittent thermodilution cardiac output measurements were obtained and blood samples taken from the tip of pulmonary artery catheter to measure hemodynamics and mixed venous oxygen saturation (SvO2).Results. By univariate analysis, RDRI was significantly correlated with SvO2, oxygen extraction ratio, left ventricular stroke work index, and cardiac index, but not heart rate, central venous pressure, mean artery pressure, pulmonary capillary wedge pressure, systemic vascular resistance index, oxygen delivery index, oxygen consumption index, arterial lactate concentration, and age. However, by multivariate analysis RDRI was significantly correlated with SvO2only.Conclusions. The present data suggests that, in mechanically ventilated patients after cardiac surgery, RDRI increases proportionally to the decrease in SvO2, thus reflecting an early vascular response to tissue hypoxia.
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Alfano, Mary Jo, Eric J. Barron, David Pollard, Brian Huntley, and Judy R. M. Allen. "Comparison of climate model results with European vegetation and permafrost during oxygen isotope stage three." Quaternary Research 59, no. 1 (January 2003): 97–107. http://dx.doi.org/10.1016/s0033-5894(02)00012-1.

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AbstractOxygen isotope stage 3 (OIS3), an interstade between approximately 60,000 and 25,000 yr B.P., presents an ideal opportunity to compare high-resolution climate simulations with the geologic record. To facilitate this comparison, the results of a mesoscale climate model (RegCM2) embedded in the GENESIS GCM are utilized to drive a vegetation model (BIOME 3.5). The BIOME output is then compared with OIS3 compilations derived from pollen. The simulated biomes agree well with the pollen-based biomes in southern Europe; however, disagreements occur in the northern part of the domain. The most striking mismatch involves the distribution of tundra. The models fail to have tundra extend to its observed position as far south as 50°N in central Europe during OIS3. The model also fails to have permafrost extend southward to its observed position between 50°N and 55°N in western Europe during OIS3. A variety of sensitivity experiments are performed to investigate these mismatches. These experiments demonstrate the importance of annual and summer temperatures and the length of the winter season in creating improved matches between the model results and the inferred distributions of vegetation and permafrost in northern Europe.
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Lake-Bakaar, Gerond, John Robertson, and Charles Aardema. "Oxygen-nutrient mismatch: a novel concept to explain how Obeticholic acid benefits NASH treatment." Journal of Hepatology 77 (July 2022): S719—S720. http://dx.doi.org/10.1016/s0168-8278(22)01757-3.

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36

YU, W. X., S. F. CUI, L. S. WU, Z. H. MAI, C. L. LI, D. F. CUI, and Z. H. CHEN. "THE STRUCTURE OFBaTiO3ANDBaTiO3-YBa2Cu3O7-δTHIN FILMS STUDIED BY X-RAY TRIPLE-AXIS DIFFRACTION." Modern Physics Letters B 13, no. 12n13 (June 10, 1999): 441–50. http://dx.doi.org/10.1142/s0217984999000555.

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The structures of BaTiO3thin films and BaTiO3/ YBa2Cu3O7-δbilayer films grown on SrTiO3and LaAlO3substrates, respectively by pulsed laser deposition, have been investigated by X-ray triple-axis diffraction. The orientation, the interface mismatch and strain status, and the in-plane and perpendicular lattice constants of the epilayers have been determined by reciprocal space map analysis. The results show that both the lattice constants and the structural imperfections of the BaTiO3layers are relevant to the oxygen partial pressure. The a⊥/a‖increases while the full width at half maximum (FWHM) of the rocking curves decreases with the decrease in the partial oxygen pressure.
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37

Manfredi, Roberto, Monica Verdoia, Paolo Compagnucci, Alessandro Barbarossa, Giulia Stronati, Michela Casella, Antonio Dello Russo, Federico Guerra, and Giuseppe Ciliberti. "Angina in 2022: Current Perspectives." Journal of Clinical Medicine 11, no. 23 (November 22, 2022): 6891. http://dx.doi.org/10.3390/jcm11236891.

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Angina is the main symptom of ischemic heart disease; mirroring a mismatch between oxygen supply and demand. Epicardial coronary stenoses are only responsible for nearly half of the patients presenting with angina; whereas in several cases; symptoms may underlie coronary vasomotor disorders; such as microvascular dysfunction or epicardial spasm. Various medications have been proven to improve the prognosis and quality of life; representing the treatment of choice in stable angina and leaving revascularization only in particular coronary anatomies or poorly controlled symptoms despite optimal medical therapy. Antianginal medications aim to reduce the oxygen supply-demand mismatch and are generally effective in improving symptoms; quality of life; effort tolerance and time to ischemia onset and may improve prognosis in selected populations. Since antianginal medications have different mechanisms of action and side effects; their use should be tailored according to patient history and potential drug-drug interactions. Angina with non-obstructed coronary arteries patients should be phenotyped with invasive assessment and treated accordingly. Patients with refractory angina represent a higher-risk population in which some therapeutic options are available to reduce symptoms and improve quality of life; but robust data from large randomized controlled trials are still lacking.
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38

Putensen, Christian, Jukka Räsänen, Gabriele Putensen-Himmer, and John B. Downs. "Effect of Low Isoflurane Concentrations on the Ventilation–Perfusion Distribution in Injured Canine Lungs." Anesthesiology 97, no. 3 (September 1, 2002): 652–59. http://dx.doi.org/10.1097/00000542-200209000-00020.

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Background Rapid recovery and weaning from ventilatory support and cardiovascular stability are suggested advantages of isoflurane inhalation, in concentrations ranging from 0.1 to 0.6 vol%, for long-term sedation in mechanical ventilated patients. This study was designed to determine whether isoflurane in low concentrations impairs pulmonary gas exchange by increasing ventilation and perfusion (V(A)/Q) mismatch during lung injury. Methods Fourteen anesthetized dogs received in random order 0, 0.25, or 0.5 vol% end-tidal isoflurane before and after induction of lung injury with oleic acid. Gas exchange was assessed by blood gas analysis and by estimating the V(A)/Q distributions using the multiple inert gas elimination technique. Results Administration of oleic acid produced a lung injury with severe V(A)/Q mismatch and 38 +/- 4% intrapulmonary shunting of blood. During lung injury, isoflurane accounted for a dose-related increase in blood flow to shunt units from 38 +/- 4 to 42 +/- 3 (0.25 vol%) and 48 +/- 4% (0.5 vol%) (P &lt; 0.05), dispersion pulmonary blood flow distribution from 0.94 +/- 0.07 to 1.01 +/- 0.09 (0.25 vol%) and 1.11 +/- 0.11% (0.5 vol%) (P &lt; 0.05), and a decrease in perfusion of normal V(A)/Q units from 58 +/- 5 to 55 +/- 4 (0.25 vol%) and 50 +/- 4% (0.5 vol%) (P &lt; 0.05) (mean +/- SE). Isoflurane decreased arterial oxygen partial pressure from 72 +/- 4 to 62 +/- 4 mmHg (0.25 vol%) and 56 +/- 4 mmHg (0.5 vol%) (P &lt; 0.05) and oxygen delivery from 573 +/- 21 to 529 +/- 19 ml. kg. min (0.25 vol%) and 505 +/- 22 ml. kg. min (0.5 vol%) (P &lt; 0.05). Gas exchange, perfusion of shunt and normal V(A)/Q units, and pulmonary blood flow distribution was similar in absence of lung injury with and without isoflurane. Isoflurane 0.5 vol% lowered cardiac output during all conditions (P &lt; 0.05). CONCLUSIONS Inhalation of low concentrations of isoflurane contributed to increased V(A)/Q mismatch and decreased systemic blood flow and oxygen delivery in mechanically ventilated animals with injured lungs.
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Alders, David J. C., A. B. Johan Groeneveld, Thomas W. Binsl, and Johannes H. G. M. van Beek. "Progressively heterogeneous mismatch of regional oxygen delivery to consumption during graded coronary stenosis in pig left ventricle." American Journal of Physiology-Heart and Circulatory Physiology 309, no. 10 (November 15, 2015): H1708—H1719. http://dx.doi.org/10.1152/ajpheart.00657.2014.

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In normal hearts, myocardial perfusion is fairly well matched to regional metabolic demand, although both are distributed heterogeneously. Nonuniform regional metabolic vulnerability during coronary stenosis would help to explain nonuniform necrosis during myocardial infarction. In the present study, we investigated whether metabolism-perfusion correlation diminishes during coronary stenosis, indicating increasing mismatch of regional oxygen supply to demand. Thirty anesthetized male pigs were studied: controls without coronary stenosis ( n = 11); group I, left anterior descending (LAD) coronary stenosis leading to coronary perfusion pressure reduction to 70 mmHg ( n = 6); group II, stenosis with perfusion pressure of about 35 mmHg ( n = 6); and group III, stenosis with perfusion pressure of 45 mmHg combined with adenosine infusion ( n = 7). [2-13C]- and [1,2-13C]acetate infusion was used to calculate regional O2 consumption from glutamate NMR spectra measured for multiple tissue samples of about 100 mg dry mass in the LAD region. Blood flow was measured with microspheres in the same regions. In control hearts without stenosis, regional oxygen extraction did not correlate with basal blood flow. Average myocardial O2 delivery and consumption decreased during coronary stenosis, but vasodilation with adenosine counteracted this. Regional oxygen extraction was on average decreased during stenosis, suggesting adaptation of metabolism to lower oxygen supply after half an hour of ischemia. Whereas regional O2 delivery correlated with O2 consumption in controls, this relation was progressively lost with graded coronary hypotension but partially reestablished by adenosine infusion. Therefore, coronary stenosis leads to heterogeneous metabolic stress indicated by decreasing regional O2 supply to demand matching in myocardium during partial coronary obstruction.
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40

Yuan, Shu, Si-Cong Jiang, Zhong-Wei Zhang, Yu-Fan Fu, Jing Hu, and Zi-Lin Li. "The Role of Alveolar Edema in COVID-19." Cells 10, no. 8 (July 26, 2021): 1897. http://dx.doi.org/10.3390/cells10081897.

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The coronavirus disease 2019 (COVID-19) has spread over the world for more than one year. COVID-19 often develops life-threatening hypoxemia. Endothelial injury caused by the viral infection leads to intravascular coagulation and ventilation-perfusion mismatch. However, besides above pathogenic mechanisms, the role of alveolar edema in the disease progression has not been discussed comprehensively. Since the exudation of pulmonary edema fluid was extremely serious in COVID-19 patients, we bring out a hypothesis that severity of alveolar edema may determine the size of poorly-ventilated area and the blood oxygen content. Treatments to pulmonary edema (conservative fluid management, exogenous surfactant replacements and ethanol–oxygen vapor therapy hypothetically) may be greatly helpful for reducing the occurrences of severe cases. Given that late mechanical ventilation may cause mucus (edema fluid) to be blown deep into the small airways, oxygen therapy should be given at the early stages. The optimal time and blood oxygen saturation (SpO2) threshold for oxygen therapy are also discussed.
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41

Wagner, T., A. D. Polli, G. Richter, and H. Stanzick. "Epitaxial Growth of Metals on (100) SrTiO3: The Influence of Lattice Mismatch and Reactivity." International Journal of Materials Research 92, no. 7 (July 1, 2001): 701–6. http://dx.doi.org/10.1515/ijmr-2001-0133.

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Abstract The model system Me/(100) SrTiO3 (Me: Pd, Pt, Cu, Ni, Cr, Mo, Nb, and Al) was used to show that there exists a simple correlation between the formation of particular epitaxial orientations, the lattice mismatch between metal and SrTiO3, and the oxygen affinity of the metal. The growth of the metal films on the (100) SrTiO3 surface was studied by reflection high-energy electron diffraction. Most metals (Pd, Pt, Ni, Nb and Al) grew with the following epitaxial orientation relationship on the SrTiO3: (100) SrTiO3 | | (100) Me, [001] SrTiO3 | | [001] Me. A second epitaxial orientation relationship was detected for Cr and Mo: (100) SrTiO3 | | (100) Cr, Mo, [001] SrTiO3 | | [011] Cr, Mo. For Mo, this orientation was detected only at very high growth temperatures. For each of the epitaxial orientation relationships, the substrate and film planes of four fold symmetry were parallel. Besides the second epitaxial orientation relationship, a third epitaxial orientation relationship was detected for Mo at growth temperatures below 900 K: (100) SrTiO3 | | (110) Mo, [001] SrTiO3 | | [001] Mo. In contrast to all other metals under investigation, Cu grew with a (111) fiber texture on the (100) SrTiO3 surface. The appearance of the first two epitaxial orientation relationships can be interpreted with a simple relationship between the metals’ oxygen affinities and the lattice mismatches with SrTiO3. This relationship can be used for other metals to predict epitaxy on the (100) SrTiO3 surface.
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42

Gaspari, Romolo J., and David Paydarfar. "Pulmonary effects of intravenous atropine induce ventilation perfusion mismatch." Canadian Journal of Physiology and Pharmacology 92, no. 5 (May 2014): 399–404. http://dx.doi.org/10.1139/cjpp-2012-0429.

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Atropine is used for a number of medical conditions, predominantly for its cardiovascular effects. Cholinergic nerves that innervate pulmonary smooth muscle, glands, and vasculature may be affected by anticholinergic medications. We hypothesized that atropine causes alterations in pulmonary gas exchange. We conducted a prospective interventional study with detailed physiologic recordings in anesthetized, spontaneously breathing rats (n = 8). Animals breathing a normoxic gas mixture titrated to a partial arterial pressure of oxygen of 110–120 were exposed to an escalating dose of intravenous atropine (0.001, 0.01, 0.1, 5.0, and 20.0 mg/kg body mass). Arterial blood gas measurements were recorded every 2 min (×5) at baseline, and following each of the 5 doses of atropine. In addition, the animals regional pulmonary blood flow was measured using neutron-activated microspheres. Oxygenation decreased immediately following intravenous administration of atropine, despite a small increase in the volume of inspired air with no change in respiratory rate. Arterial blood gas analysis showed an increase in pulmonary dysfunction, characterized by a widening of the alveolar–arteriole gradient (p < 0.003 all groups except for the lowest dose of atropine). The microsphere data demonstrates an abrupt and marked heterogeneity of pulmonary blood flow following atropine treatment. In conclusion, atropine was found to decrease pulmonary gas exchange in a dose-dependent fashion in this rat model.
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43

Altemeier, William A., Steve McKinney, Melissa Krueger, and Robb W. Glenny. "Effect of posture on regional gas exchange in pigs." Journal of Applied Physiology 97, no. 6 (December 2004): 2104–11. http://dx.doi.org/10.1152/japplphysiol.00072.2004.

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Although recent high-resolution studies demonstrate the importance of nongravitational determinants for both pulmonary blood flow and ventilation distributions, posture has a clear impact on whole lung gas exchange. Deterioration in arterial oxygenation with repositioning from prone to supine posture is caused by increased heterogeneity in the distribution of ventilation-to-perfusion ratios. This can result from increased heterogeneity in regional blood flow distribution, increased heterogeneity in regional ventilation distribution, decreased correlation between regional blood flow and ventilation, or some combination of the above (Wilson TA and Beck KC, J Appl Physiol 72: 2298–2304, 1992). We hypothesize that, although repositioning from prone to supine has relatively small effects on overall blood flow and ventilation distributions, regional changes are poorly correlated, resulting in regional ventilation-perfusion mismatch and reduction in alveolar oxygen tension. We report ventilation and perfusion distributions in seven anesthetized, mechanically ventilated pigs measured with aerosolized and injected microspheres. Total contributions of pulmonary structure and posture on ventilation and perfusion heterogeneities were quantified by using analysis of variance. Regional gradients of posture-mediated change in ventilation, perfusion, and calculated alveolar oxygen tension were examined in the caudocranial and ventrodorsal directions. We found that pulmonary structure was responsible for 74.0 ± 4.7% of total ventilation heterogeneity and 63.3 ± 4.2% of total blood flow heterogeneity. Posture-mediated redistribution was primarily oriented along the caudocranial axis for ventilation and along the ventrodorsal axis for blood flow. These mismatched changes reduced alveolar oxygen tension primarily in the dorsocaudal lung region.
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44

Zhu, Yimei, A. R. Moodenbaugh, J. M. Zuo, and M. Suenaga. "Quantiative analysis of grain boundaries in YBa2Cu3O7-δ using a 20Å high-resolution probe." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 966–67. http://dx.doi.org/10.1017/s0424820100172565.

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One challenge for high Tc superconductor research is to overcome the low intergranular transport currents which hinder practical applications. Evidence shows that lattice mismatch at the boundaries contributes to the depletion in charge carriers (holes), while the strain fields surrounding the cores of boundary dislocations suppress the superconducting order parameter. Using high-spatialresolution EDX, EELS and CBED techniques with a 20 Å field emission probe, we studied cation segregation, variations in oxygen/hole content, and lattice parameters at and across grain boundaries for various Σ and near-Σ boundaries in bulk YBa2Cu3O7-δ. The geometry of those arbitrary grain boundaries was modeled using the constrained Coincidence Site Lattice (cCSL) theory, which requires c2/a2 being rational for coincidence boundaries in non-cubic crystals.In this presentation, we report our quantitative and simultaneous measurements of lattice parameters, and of oxygen/hole content at the boundary regions. The oxygen/hole density was quantified by guassian fitting to the observed oxygen K-edge spectra and comparing them with those from the same batch which had undergone oxygen reduction process (Fig.1).
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45

Zhu, Yimei, and J. M. Zuo. "Quantitative analysis of hole density and lattice parameter at grain boundaries in YBa2Cu3O7-δ." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 322–23. http://dx.doi.org/10.1017/s0424820100137987.

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One challenge for high Tc superconductor research is to overcome the low intergranular transport currents which hinder practical applications. Evidence shows that lattice mismatch at the boundaries contributes to the depletion in charge carriers (holes), while the strain fields surrounding the cores of boundary dislocations suppress the superconducting order parameter. Using high-spatial resolution EDX, EELS and CBED techniques with a 20 Å field emission probe, we studied cation segregation, variations in oxygen/hole content, and lattice parameters at and across grain boundaries for various Σ and near-Σ boundaries in bulk YBa2Cu3O7-δ. The geometry of those arbitrary grain boundaries was modeled using the constrained Coincidence Site Lattice (cCSL) theory, which requires c2/a2 being rational for coincidence boundaries in non-cubic crystals.In this presentation, we report our quantitative and simultaneous measurements of oxygen/hole content (Fig.l) and of lattice parameters (Fig.3) at the boundary regions. The oxygen/hole density was quantified by guassian fitting to the observed oxygen K-edge spectra (Fig.2) and comparing them with those from the same batch which had undergone oxygen reduction process (oxygen content was determined by thermal gravimetric analysis and mass-measurement techniques).
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46

Lmouchter, Mohamed, and Minoru Suzuki. "Sustained coherent epitaxy and role of oxygen vacancies in La0.7Sr0.3MnO3−δ thin films grown on SrTiO3 by sputtering." European Physical Journal Applied Physics 94, no. 3 (June 2021): 30301. http://dx.doi.org/10.1051/epjap/2021200365.

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Ferromagnetic La0.7Sr0.3MnO3−δ (LSMO) epitaxial thin films of single-crystal quality with very smooth surfaces are grown on SrTiO3 (100) substrates by on-axis rf magnetron sputtering. We find that the resistivity and the spontaneous magnetization for these 180 nm thick films are nearly equal to those of single crystals after thermal annealing. On the other hand, the Curie temperature TC is no higher than 270 K, a value far below the bulk one, which is quite unusual. As a clue to this riddle, we note a strong correlation between the lattice constant for these films and the amount of oxygen vacancies in the case of LSMO, an oxygen-nonstoichiometric oxide. From this, we conclude that the sustained coherent epitaxy takes place to match the lattice mismatch of 0.8% by incorporating a limited amount of oxygen vacancies, which relaxes the film in-plane stress while functions to significantly reduce TC.
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47

Stramma, L., A. Oschlies, and S. Schmidtko. "Mismatch between observed and modeled trends in dissolved upper-ocean oxygen over the last 50 yr." Biogeosciences 9, no. 10 (October 22, 2012): 4045–57. http://dx.doi.org/10.5194/bg-9-4045-2012.

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Abstract. Observations and model runs indicate trends in dissolved oxygen (DO) associated with current and ongoing global warming. However, a large-scale observation-to-model comparison has been missing and is presented here. This study presents a first global compilation of DO measurements covering the last 50 yr. It shows declining upper-ocean DO levels in many regions, especially the tropical oceans, whereas areas with increasing trends are found in the subtropics and in some subpolar regions. For the Atlantic Ocean south of 20° N, the DO history could even be extended back to about 70 yr, showing decreasing DO in the subtropical South Atlantic. The global mean DO trend between 50° S and 50° N at 300 dbar for the period 1960 to 2010 is –0.066 μmol kg−1 yr−1. Results of a numerical biogeochemical Earth system model reveal that the magnitude of the observed change is consistent with CO2-induced climate change. However, the pattern correlation between simulated and observed patterns of past DO change is negative, indicating that the model does not correctly reproduce the processes responsible for observed regional oxygen changes in the past 50 yr. A negative pattern correlation is also obtained for model configurations with particularly low and particularly high diapycnal mixing, for a configuration that assumes a CO2-induced enhancement of the C : N ratios of exported organic matter and irrespective of whether climatological or realistic winds from reanalysis products are used to force the model. Depending on the model configuration the 300 dbar DO trend between 50° S and 50° N is −0.027 to –0.047 μmol kg−1 yr−1 for climatological wind forcing, with a much larger range of –0.083 to +0.027 μmol kg−1 yr−1 for different initializations of sensitivity runs with reanalysis wind forcing. Although numerical models reproduce the overall sign and, to some extent, magnitude of observed ocean deoxygenation, this degree of realism does not necessarily apply to simulated regional patterns and the representation of processes involved in their generation. Further analysis of the processes that can explain the discrepancies between observed and modeled DO trends is required to better understand the climate sensitivity of oceanic oxygen fields and predict potential DO changes in the future.
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48

Dang, Xiaolin, Donglin Zhao, Tong Guo, Xiaomeng Fan, Jimei Xue, Fang Ye, Yongsheng Liu, and Laifei Cheng. "Oxidation behaviors of carbon fiber reinforced multilayer SiC-Si3N4 matrix composites." Journal of Advanced Ceramics 11, no. 2 (January 11, 2022): 354–64. http://dx.doi.org/10.1007/s40145-021-0539-1.

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AbstractOxidation behaviors of carbon fiber reinforced SiC matrix composites (C/SiC) are one of the most noteworthy properties. For C/SiC, the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coefficients of thermal expansion (CTEs) and elastic modulus between carbon fiber and SiC matrix. In order to improve the oxidation resistance, multilayer SiC-Si3N4 matrices were fabricated by chemical vapor infiltration (CVI) to alleviate the above two kinds of mismatch and change the local stress distribution. For the oxidation of C/SiC with multilayer matrices, matrix microcracks would be deflected at the transition layer between different layers of multilayer SiC-Si3N4 matrix to lengthen the oxygen diffusion channels, thereby improving the oxidation resistance of C/SiC, especially at 800 and 1000 °C. The strength retention ratio was increased from 61.9% (C/SiC-SiC/SiC) to 75.7% (C/SiC-Si3N4/SiC/SiC) and 67.8% (C/SiC-SiC/Si3N4/SiC) after oxidation at 800 °C for 10 h.
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49

ZHU, HONG, MASANORI OKADA, ATSUSHI KAMIYA, AJAY KRISHNO SARKAR, MASAHITO MATSUI, MD MOTIN SEIKH, and TAMIO ENDO. "FABRICATION OF LSMO SINGLE LAYERS AND LSMO/YBCO DOUBLE LAYERS." International Journal of Nanoscience 05, no. 04n05 (August 2006): 511–15. http://dx.doi.org/10.1142/s0219581x06004711.

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( La , Sr ) MnO 3 (LSMO) single-layer and LSMO/YBCO double-layer films have been grown on LAO and MgO substrates using ion beam sputtering. For LSMO single-layer films, the highly epitaxial films can be grown at lower substrate temperatures down to 500°C. The epitaxy of the films, which is degraded with increasing TS, can be restored by supply of plasma oxygen. Smaller lattice mismatch of LSMO on LAO gives two-dimensional step-and-terrace type growth, whereas on MgO grain type growth is observed due to larger mismatch. For the double-layer films, LSMO layer can be grown epitaxially on a-oriented YBCO underlayer, but a part of the underlying a-YBCO is changed into c-YBCO during the deposition of overlayer. For c-YBCO underlayer, a part of the underlying c-YBCO is changed into (110)-oriented phase after the deposition of overlayer. Then it is necessary to deposit the overlayer at lower temperatures.
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50

Baldwin, Jacinta, Rodney J. Snow, Michael F. Carey, and Mark A. Febbraio. "Muscle IMP accumulation during fatiguing submaximal exercise in endurance trained and untrained men." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 277, no. 1 (July 1, 1999): R295—R300. http://dx.doi.org/10.1152/ajpregu.1999.277.1.r295.

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To examine the effect of training status on muscle metabolism during exercise, seven endurance-trained [peak oxygen uptake (V˙o2 peak) = 65.8 ± 2.4 ml ⋅ kg−1⋅ min−1] and six untrained (V˙o2 peak= 46.2 ± 1.9 ml ⋅ kg−1⋅ min−1) men cycled to fatigue at a work rate calculated to require 70%V˙o2 peak. Time to exhaustion was 36% longer ( P < 0.01) in trained (TR) compared with untrained (UT) men (148 ± 11 vs. 95 ± 8 min). Although intramuscular glycogen content was reduced ( P < 0.05) in both TR and UT at fatigue, IMP, a marker of a mismatch between ATP supply and demand, was only elevated ( P < 0.01) in UT muscle at fatigue and was approximately fourfold higher at this point in UT compared with TR. These data demonstrate that fatiguing submaximal exercise was associated with a similar low level of intramuscular glycogen in both TR and UT men, but a mismatch between ATP supply and demand only occurred in UT individuals.
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