Influence of oxygen partial pressure on surface tension and its temperature coefficient of molten iron

NASA Astrophysics Data System (ADS)

Ozawa, S.; Suzuki, S.; Hibiya, T.; Fukuyama, H.

2011-01-01

Influences of oxygen partial pressure, PO2, of ambient atmosphere and temperature on surface tension and its temperature coefficient for molten iron were experimentally investigated by an oscillating droplet method using an electromagnetic levitation furnace. We successfully measured the surface tension of molten iron over a very wide temperature range of 780 K including undercooling condition in a well controlled PO2 atmosphere. When PO2 is fixed at 10-2 Pa at the inlet of the chamber, a "boomerang shape" temperature dependence of surface tension was experimentally observed; surface tension increased and then decreased with increasing temperature. The pure surface tension of molten iron was deduced from the negative temperature coefficient in the boomerang shape temperature dependence. When the surface tension was measured under the H2-containing gas atmosphere, surface tension did not show a linear relationship against temperature. The temperature dependence of the surface tension shows anomalous kink at around 1850 K due to competition between the temperature dependence of PO2 and that of the equilibrium constant of oxygen adsorption.

Endothelial protection: avoiding air bubble formation at the phacoemulsification tip.

PubMed

Kim, Eung Kweon; Cristol, Stephen M; Kang, Shin J; Edelhauser, Henry F; Yeon, Dong-Soo; Lee, Jae Bum

2002-03-01

To investigate the conditions under which bubbles form during phacoemulsification. Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. In the first part of the study, the partial pressure of oxygen (pO(2)) was used as a surrogate measure for the partial pressure of air. Irrigation solutions packaged in glass and plastic containers were studied. A directly vented glass bottle was also tested. The pO(2) of the various irrigation solutions was measured as the containers were emptied. In the second part, phacoemulsification procedures were performed in rabbit eyes with different power settings and different irrigation solutions. Intracameral bubble formation during the procedure was recorded. Following the phacoemulsification procedures, the corneas were stained for F-actin and examined for endothelial injury. The initial pO(2) in irrigation solutions packaged in glass bottles was about half that at atmospheric levels; in solutions packaged in plastic, it was at atmospheric levels. As irrigation solutions were drained from the container, the pO(2) of the solution tended to rise toward atmospheric levels. The rate of pO(2) increase was markedly reduced by using a directly vented glass bottle. In the phacoemulsification procedures, bubble formation was most likely to occur with higher pO(2) and higher power settings. Observation of bubbles by the surgeon was highly correlated with endothelial damage. Keeping the pO(2) low reduced the risk of endothelial damage, especially at higher phacoemulsification powers. The packaging of irrigation solutions was the most important factor in controlling the initial pO(2) of the solution. The pO(2) can be minimized throughout a phacoemulsification procedure by using a directly vented glass bottle.

Monitoring in microvascular tissue transfer by measurement of oxygen partial pressure: four years experience with 125 microsurgical transplants.

PubMed

Jonas, René; Schaal, Thomas; Krimmel, Michael; Gülicher, Dirk; Reinert, Siegmar; Hoffmann, Jürgen

2013-06-01

In a prospective study, the characteristics and benefit of an invasive measurement of oxygen partial pressure (pO(2)) with the aid of a polarographic sensor were investigated in 125 microsurgical reconstructions of the head and neck area over a period of 45 months. Measurements were performed over 96 h in eight different types of microsurgically revascularized flaps for extra- and intraoral reconstructions and were evaluated separately for each flap type. Of 125 reconstructions the system indicated malperfusion in 18 cases. Salvage surgery was performed in 17 cases due to venous thrombosis (6 cases), arterial thrombosis (3 cases), a combination of arterial and venous thrombosis (2 cases), rheological problems (3 cases), venous insufficiency by hematoma (2 cases) and kinking of vessels (1 case). In 10 cases salvage surgery was successful, 7 flaps were lost despite salvage surgery. In all these cases, the polarographic probe indicated the necessity of salvage surgery correctly. After 96 h no malperfusion was seen. Postoperatively, a common and characteristic development of the oxygen partial pressure in different types of flaps was seen. Initially, a clear increase of pO(2) could be measured. During 96 h, a slow decrease of pO(2) was observed. In conclusion polarographic measurement of pO(2) can be an excellent apparative supplement for the postoperative clinical control of microsurgically revascularized transplants. In buried flaps, this technique represents the only reliable method for transplant monitoring. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Impact of partial pressure of oxygen in blood samples on the performance of systems for self-monitoring of blood glucose.

PubMed

Schmid, Christina; Baumstark, Annette; Pleus, Stefan; Haug, Cornelia; Tesar, Martina; Freckmann, Guido

2014-03-01

The partial pressure of oxygen (pO2) in blood samples can affect glucose measurements with oxygen-sensitive systems. In this study, we assessed the influence of different pO2 levels on blood glucose (BG) measurements with five glucose oxidase (GOD) systems and one glucose dehydrogenase (GDH) system. All selected GOD systems were indicated by the manufacturers to be sensitive to increased oxygen content of the blood sample. Venous blood samples of 16 subjects (eight women, eight men; mean age, 52 years; three with type 1 diabetes, four with type 2 diabetes, and nine without diabetes) were collected. Aliquots of each sample were adjusted to the following pO2 values: ≤45 mm Hg, approximately 70 mm Hg, and ≥150 mm Hg. For each system, five consecutive measurements on each sample were performed using the same test strip lot. Relative differences between the mean BG value at a pO2 level of approximately 70 mm Hg, which was considered to be similar to pO2 values in capillary blood samples, and the mean BG value at pO2 levels ≤45 mm Hg and ≥150 mm Hg were calculated. The GOD systems showed mean relative differences between 11.8% and 44.5% at pO2 values ≤45 mm Hg and between -14.6% and -21.2% at pO2 values ≥150 mm Hg. For the GDH system, the mean relative differences were -0.3% and -0.2% at pO2 values ≤45 mm Hg and ≥150 mm Hg, respectively. The magnitude of the pO2 impact on BG measurements seems to vary among the tested oxygen-sensitive GOD systems. The pO2 range in which oxygen-sensitive systems operate well should be provided in the product information.

Influence of partial pressure of oxygen in blood samples on measurement performance in glucose-oxidase-based systems for self-monitoring of blood glucose.

PubMed

Baumstark, Annette; Schmid, Christina; Pleus, Stefan; Haug, Cornelia; Freckmann, Guido

2013-11-01

Partial pressure of oxygen (pO2) in blood samples can affect blood glucose (BG) measurements, particularly in systems that employ the glucose oxidase (GOx) enzyme reaction on test strips. In this study, we assessed the impact of different pO2 values on the performance of five GOx systems and one glucose dehydrogenase (GDH) system. Two of the GOx systems are labeled by the manufacturers to be sensitive to increased blood oxygen content, while the other three GOx systems are not. Aliquots of 20 venous samples were adjusted to the following pO2 values: <45, ~70, and ≥150 mmHg. For each system, five consecutive measurements on each sample aliquot were performed using the same test strip lot. Relative differences between the mean BG results at pO2 ~70 mmHg, which is considered to be similar to pO2 in capillary blood samples, and the mean BG result at pO2 <45 and ≥150 mmHg were calculated. For all tested GOx systems, mean relative differences in the BG measurement results were between 6.1% and 22.6% at pO2 <45 mmHg and between -7.9% and -14.9% at pO2 ≥150 mmHg. For both pO2 levels, relative differences of all tested GOx systems were significant (p < .0001). The GDH system showed mean relative differences of -1.0% and -0.4% at pO2 values <45 and ≥150 mmHg, respectively, which were not significant. These data suggest that capillary blood pO2 variations lead to clinically relevant BG measurement deviations in GOx systems, even in GOx systems that are not labeled as being oxygen sensitive. © 2013 Diabetes Technology Society.

Temperature dependence of partial conductivities of the BaZr0.7Ce0.2Y0.1O3-δ proton conductor

NASA Astrophysics Data System (ADS)

Heras-Juaristi, Gemma; Pérez-Coll, Domingo; Mather, Glenn C.

2017-10-01

Partial conductivities are presented for BaZr0.7Ce0.2Y0.1O3-δ, an important proton conductor for protonic-ceramic fuel cells and membrane reactors. Atmospheric dependencies of impedance performed in humidified and dry O2, air, N2 and H2(10%)/N2(90%) in the temperature range 300-900 °C, supported by the modified emf method, confirm significant electron-hole and protonic contributions to transport. For very reducing and wet atmospheres, the conductivity is predominantly ionic, with a higher participation of protons with decreasing temperature and increasing water-vapour partial pressure (pH2O). From moderately reducing conditions of wet N2 to wet O2, however, the conductivity is considerably influenced by electron holes as revealed by a significant dependence of total conductivity on oxygen partial pressure (pO2). With higher pH2O, proton transport increases, with a concomitant decrease of holes and oxygen vacancies. However, the effect of pH2O is also influenced by temperature, with a greater protonic contribution at both lower temperature and pO2. Values of proton transport number tH ≈ 0.63 and electronic transport number th ≈ 0.37 are obtained at 600 °C for pH2O = 0.022 atm and pO2 = 0.2 atm, whereas tH ≈ 0.95 and th ≈ 0.05 for pO2 = 10-5 atm. A hydration enthalpy of -109 kJ mol-1 is obtained in the range 600-900 °C.

Comparing CT perfusion with oxygen partial pressure in a rabbit VX2 soft-tissue tumor model.

PubMed

Sun, Chang-Jin; Li, Chao; Lv, Hai-Bo; Zhao, Cong; Yu, Jin-Ming; Wang, Guang-Hui; Luo, Yun-Xiu; Li, Yan; Xiao, Mingyong; Yin, Jun; Lang, Jin-Yi

2014-01-01

The aim of this study was to evaluate the oxygen partial pressure of the rabbit model of the VX2 tumor using a 64-slice perfusion CT and to compare the results with that obtained using the oxygen microelectrode method. Perfusion CT was performed for 45 successfully constructed rabbit models of a VX2 brain tumor. The perfusion values of the brain tumor region of interest, the blood volume (BV), the time to peak (TTP) and the peak enhancement intensity (PEI) were measured. The results were compared with the partial pressure of oxygen (PO2) of that region of interest obtained using the oxygen microelectrode method. The perfusion values of the brain tumor region of interest in 45 successfully constructed rabbit models of a VX2 brain tumor ranged from 1.3-127.0 (average, 21.1 ± 26.7 ml/min/ml); BV ranged from 1.2-53.5 ml/100g (average, 22.2 ± 13.7 ml/100g); PEI ranged from 8.7-124.6 HU (average, 43.5 ± 28.7 HU); and TTP ranged from 8.2-62.3 s (average, 38.8 ± 14.8 s). The PO2 in the corresponding region ranged from 0.14-47 mmHg (average, 16 ± 14.8 mmHg). The perfusion CT positively correlated with the tumor PO2, which can be used for evaluating the tumor hypoxia in clinical practice.

Partial Oxygen Pressure Affects the Expression of Prognostic Biomarkers HIF-1 Alpha, Ki67, and CK20 in the Microenvironment of Colorectal Cancer Tissue.

PubMed

Zhang, Lirong; Hu, Yu; Xi, Ning; Song, Jie; Huang, Wenjing; Song, Shanshan; Liu, Yiting; Liu, Xianying; Xie, Yingjun

2016-01-01

Hypoxia is prognostically important in colorectal cancer (CRC) therapy. Partial oxygen pressure (pO 2 ) is an important parameter of hypoxia. The correlation between pO 2 levels and expression levels of prognostic biomarkers was measured in CRC tissues. Human CRC tissues were collected and pO 2 levels were measured by OxyLite. Three methods for tissue fixation were compared, including formalin, Finefix, and Finefix-plus-microwave. Immunohistochemistry (IHC) staining was conducted by using the avidin-biotin complex technique for detecting the antibodies to hypoxia inducible factor-1 (HIF-1) alpha, cytokeratin 20 (CK20), and cell proliferation factor Ki67. The levels of pO 2 were negatively associated with the size of CRC tissues. Finefix-plus-microwave fixation has the potential to replace formalin. Additionally, microwave treatment improved Finefix performance in tissue fixation and protein preservation. The percentage of positive cells and gray values of HIF-1 alpha, CK20, and Ki67 were associated with CRC development ( P < 0.05). The levels of pO 2 were positively related with the gray values of Ki67 and negatively related with the values of HIF-1 alpha and CK20 ( P < 0.05). Thus, the levels of microenvironmental pO 2 affect the expression of predictive biomarkers HIF-1 alpha, CK20, and Ki67 in the development of CRC tissues.

Preretinal partial pressure of oxygen gradients before and after experimental pars plana vitrectomy.

PubMed

Petropoulos, Ioannis K; Pournaras, Jean-Antoine C; Stangos, Alexandros N; Pournaras, Constantin J

2013-01-01

To evaluate preretinal partial pressure of oxygen (PO2) gradients before and after experimental pars plana vitrectomy. Arteriolar, venous, and intervascular preretinal PO2 gradients were recorded in 7 minipigs during slow withdrawal of oxygen-sensitive microelectrodes (10-μm tip diameter) from the vitreoretinal interface to 2 mm into the vitreous cavity. Recordings were repeated after pars plana vitrectomy and balanced salt solution (BSS) intraocular perfusion. Arteriolar, venous, and intervascular preretinal PO2 at the vitreoretinal interface were 62.3 ± 13.8, 22.5 ± 3.3, and 17.0 ± 7.5 mmHg, respectively, before vitrectomy; 97.7 ± 19.9, 40.0 ± 21.9, and 56.3 ± 28.4 mmHg, respectively, immediately after vitrectomy; and 59.0 ± 27.4, 25.2 ± 3.0, and 21.5 ± 4.5 mmHg, respectively, 2½ hours after interruption of BSS perfusion. PO2 2 mm from the vitreoretinal interface was 28.4 ± 3.6 mmHg before vitrectomy; 151.8 ± 4.5 mmHg immediately after vitrectomy; and 34.8 ± 4.1 mmHg 2½ hours after interruption of BSS perfusion. PO2 gradients were still present after vitrectomy, with the same patterns as before vitrectomy. Preretinal PO2 gradients are not eliminated after pars plana vitrectomy. During BSS perfusion, vitreous cavity PO2 is very high. Interruption of BSS perfusion evokes progressive equilibration of vitreous cavity PO2 with concomitant progressive return of preretinal PO2 gradients to their previtrectomy patterns. This indicates that preretinal diffusion of oxygen is not altered after vitrectomy. The beneficial effect of vitrectomy in ischemic retinal diseases or macular edema may be related to other mechanisms, such as increased oxygen convection currents or removal of growth factors and cytokines secreted in the vitreous.

STRUCTURE AND PHYSICAL PROPERTIES OF SOLID AND LIQUID VANADIUM PENTOXIDE.

DTIC Science & Technology

The electrical resistivity of near-stoichiometric crystalline V2O5 was measured as a function of crystal orientation and oxygen partial pressure from...25C to 300C. Conductivity is insensitive to ambient atmosphere. The activation energy for conduction is 0.20 ev. Molten V2O5 , however, is...sensitive to oxygen partial pressure. Its conductivity is proportional to P-O2 to the -1/6th power. Anomalously high electrical resistivity was observed for glassy V2O5 films. (Author)

Application of phosphorescence quenching by O2 to the investigation of O2 delivery to ocular tissues

NASA Astrophysics Data System (ADS)

Chamot, Stephane R.; Petrig, Benno L.; Pournaras, Constantin J.; Percicot, Christine L.; Lambrou, George N.; Riva, Charles E.

2001-10-01

The technique of phosphorescence quenching by O2 (PQ) allows the non-invasive measurement of the partial pressure of oxygen in blood (pO2blood). This technique and its application to the investigation of the pO2blood in the microvasculature of the retina and optic nerve head (ONH) of two animal species is described. Using the imaging mode of PQ, 2-dimensional pO2blood maps were obtained to investigate the response of the pO2blood to various physiological stimuli in miniature pigs and the effect of experimental glaucoma in monkeys. Applied in its focal mode, PQ allows measurements of the pO2blood with a time resolution of 1 second and is adequate to investigate the pO2blood time course during light stimulation.

Magnetism of Amorphous and Nano-Crystallized Dc-Sputter-Deposited MgO Thin Films

PubMed Central

Mahadeva, Sreekanth K.; Fan, Jincheng; Biswas, Anis; Sreelatha, K.S.; Belova, Lyubov; Rao, K.V.

2013-01-01

We report a systematic study of room-temperature ferromagnetism (RTFM) in pristine MgO thin films in their amorphous and nano-crystalline states. The as deposited dc-sputtered films of pristine MgO on Si substrates using a metallic Mg target in an O2 containing working gas atmosphere of (N2 + O2) are found to be X-ray amorphous. All these films obtained with oxygen partial pressure (PO2) ~10% to 80% while maintaining the same total pressure of the working gas are found to be ferromagnetic at room temperature. The room temperature saturation magnetization (MS) value of 2.68 emu/cm3 obtained for the MgO film deposited in PO2 of 10% increases to 9.62 emu/cm3 for film deposited at PO2 of 40%. However, the MS values decrease steadily for further increase of oxygen partial pressure during deposition. On thermal annealing at temperatures in the range 600 to 800 °C, the films become nanocrystalline and as the crystallite size grows with longer annealing times and higher temperature, MS decreases. Our study clearly points out that it is possible to tailor the magnetic properties of thin films of MgO. The room temperature ferromagnetism in MgO films is attributed to the presence of Mg cation vacancies. PMID:28348346

The effect of oxygen partial pressure on protein synthesis and collagen hydroxylation by mature periodontal tissues maintained in organ cultures

PubMed Central

Yen, Edwin H. K.; Sodek, Jaro; Melcher, Antony H.

1979-01-01

Mature periodontal tissues from adult-mouse first mandibular molars were cultured in a continuous-flow organ-culture system which allowed the regulation of both ascorbic acid concentration and pO2 (oxygen partial pressure). Protein synthesis was measured by analysing the incorporation of [3H]proline into collagenous and non-collagenous proteins during the last 24h of a 2-day culture. At low pO2 [16.0kPa (approx. 120mmHg)] approx. 60% of protein-incorporated [3H]proline was found in collagenous proteins. However, it was evident that this collagen was considerably underhydroxylated. At high pO2 [56.0kPa (approx. 420mmHg)], both the amount of collagen deposited in the tissues and the degree of hydroxylation were increased considerably. In contrast, no significant effect on non-collagenous protein was observed. Tissues cultured at low pO2 for the first 48h were unable to respond to a subsequent increase in pO2 during the last 24h. Analysis of pepsin-solubilized collagen α-chains labelled with [14C]glycine demonstrated the synthesis of both type-I and type-III collagens by explants cultured for 48h at high pO2. Type-III collagen comprised 20–30% of the radioactivity in α-chains in both the periodontal ligament and the tissues of the alveolar process. The pattern of protein synthesis in the alveolar tissues at high pO2 was similar to that observed in these tissues in vivo. However, in the cultured periodontal ligament the proportions of non-collagenous proteins and type-III collagens were increased in comparison with the tissue in vivo. PMID:454369

Impact of Partial Pressure of Oxygen in Blood Samples on the Performance of Systems for Self-Monitoring of Blood Glucose

PubMed Central

Baumstark, Annette; Pleus, Stefan; Haug, Cornelia; Tesar, Martina; Freckmann, Guido

2014-01-01

Abstract Background: The partial pressure of oxygen (pO2) in blood samples can affect glucose measurements with oxygen-sensitive systems. In this study, we assessed the influence of different pO2 levels on blood glucose (BG) measurements with five glucose oxidase (GOD) systems and one glucose dehydrogenase (GDH) system. All selected GOD systems were indicated by the manufacturers to be sensitive to increased oxygen content of the blood sample. Materials and Methods: Venous blood samples of 16 subjects (eight women, eight men; mean age, 52 years; three with type 1 diabetes, four with type 2 diabetes, and nine without diabetes) were collected. Aliquots of each sample were adjusted to the following pO2 values: ≤45 mm Hg, approximately 70 mm Hg, and ≥150 mm Hg. For each system, five consecutive measurements on each sample were performed using the same test strip lot. Relative differences between the mean BG value at a pO2 level of approximately 70 mm Hg, which was considered to be similar to pO2 values in capillary blood samples, and the mean BG value at pO2 levels ≤45 mm Hg and ≥150 mm Hg were calculated. Results: The GOD systems showed mean relative differences between 11.8% and 44.5% at pO2 values ≤45 mm Hg and between −14.6% and −21.2% at pO2 values ≥150 mm Hg. For the GDH system, the mean relative differences were −0.3% and −0.2% at pO2 values ≤45 mm Hg and ≥150 mm Hg, respectively. Conclusions: The magnitude of the pO2 impact on BG measurements seems to vary among the tested oxygen-sensitive GOD systems. The pO2 range in which oxygen-sensitive systems operate well should be provided in the product information. PMID:24205977

The influence of a hyperbaric environment and increased oxygen partial pressure on the corrosion of dental alloys.

PubMed

Mehl, Christian; Heblich, Frank; Lenz, Rudolf; Ludwig, Klaus; Kern, Matthias

2011-09-01

The purpose of this in-vitro study was to determine whether there is a correlation between a hyperbaric environment or increased oxygen partial pressure and the corrosion of dental alloys used for dental restorations in divers. Samples of three commercially available dental alloys (palladium-based, reduced-gold-content and high-gold-content) were tested in the DIN EN ISO 1562 static immersion test and the amount of dissolved ions measured by atomic absorption spectrometry. The specimens were exposed to one of the following three conditions: normobaric and normoxic conditions (PO2 21 kPa); 608 kPa (6 bar, PO2 127 kPa) pressurised air in a pressure chamber or 506 kPa (5 bar, PO2 304 kPa) pressurised nitrox in a pressure chamber. None of the exposures suggested a correlation between increased ion solubility as a measure of corrosion and increased ambient pressure of the three alloys. The reduced-gold-content alloy released zinc ions at twice the weekly recommended dose. When the palladium-based alloy was exposed to a hyperbaric or hyperbaric/hyperoxic environment, ion solubility increased only slightly for gallium and silver. Within the limited sample size of the current study it can be concluded that hyperbaric and/or hyperoxic conditions do not seem to be a risk for increased corrosion for any of the three tested alloys.

Cullin 5 Expression in the Rat: Cellular and Tissue Distribution, and Changes in Response to Water Deprivation and Hemorrhagic Shock

DTIC Science & Technology

2003-02-28

of Health p53 tumor suppressor PBS phosphate buffered saline PCO2 partial pressure of carbon dioxide PO2 partial pressure of oxygen PCR...buffered saline TTBS tween-20 tris buffered saline TonEBP tonicity-response enhancer binding protein TSNRP TriService Nursing Research Program...growth and metabolism (Hochstrasser, 1995; Deshaies, 1999). Although traditionally seen as no more than a means of eliminating no longer needed

Influence of Negative-Pressure Wound Therapy on Tissue Oxygenation in Diabetic Feet.

PubMed

Jung, Jae-A; Yoo, Ki-Hyun; Han, Seung-Kyu; Lee, Ye-Na; Jeong, Seong-Ho; Dhong, Eun-Sang; Kim, Woo-Kyung

2016-08-01

Negative-pressure wound therapy (NPWT) has become a common wound care treatment modality for a variety of wounds. Several previous studies have reported that NPWT increases blood flow in the wound bed. However, NPWT might decrease tissue oxygenation in the wound bed because the foam sponge of NPWT compresses the wound bed under the influence of the applied negative pressure. Adequate tissue oxygenation is an essential consideration during diabetic foot management, and the foot is more sensitive to ischemia than any other region. Furthermore, the issue as to whether NPWT reduces or increases tissue oxygenation in diabetic feet has never been correctly addressed. The aim of this study was to evaluate the influence of NPWT on tissue oxygenation in diabetic feet. Transcutaneous partial oxygen pressures (TcPO2) were measured to determine tissue oxygenation levels beneath NPWT dressings on 21 feet of 21 diabetic foot ulcer patients. A TcPO2 sensor was fixed at the tarsometatarsal area of contralateral unwounded feet. A suction pressure of -125 mm Hg was applied until TcPO2 reached a steady state. The TcPO2 values for diabetic feet were measured before, during, and after NPWT. The TcPO2 levels decreased significantly after applying NPWT in all patients. Mean TcPO2 values before, during, and after therapy were 44.6 (SD, 15.2), 6.0 (SD, 7.1), and 40.3 (SD, 16.4) mm Hg (P < .01), respectively. These results show that NPWT significantly reduces tissue oxygenation levels in diabetic feet.

Electrical conductivity of cobalt doped La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ

NASA Astrophysics Data System (ADS)

Wang, Shizhong; Wu, Lingli; Liang, Ying

La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10 -5 atm) and low oxygen partial pressure regions (<10 -15 atm). However, the electrical conductivity in LSGM8282 had no dependency on the oxygen partial pressure. At temperatures higher than 1073 K, PO2 dependencies of the free electron conductivities in LSGM8282, LSGMC5 and LSGMC8.5 were about -1/4, and PO2 dependencies of the electron hole conductivities were about 0.25, 0.12 and 0.07, respectively. Oxygen ion conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high and low oxygen partial pressure regions, which was due to the increase in the concentration of oxygen vacancies. The change in the concentration of oxygen vacancies and the valence of cobalt with oxygen partial pressure were determined using a thermo-gravimetric technique. Both the electronic conductivity and oxygen ion conductivity in cobalt doped lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number.

Oxygen and carbon dioxide in the marine intertidal environment: diurnal and tidal changes in rockpools.

PubMed

Truchot, J P; Duhamel-Jouve, A

1980-03-01

Water oxygen partial pressure (PO2), pH, titration alkalinity (TA), temperature and salinity were measured hourly in rockpools during emersion periods occuring at various times of the diurnal cycle. Measurements allowed calculation of oxygen concentration (CO2), CO2 partial pressure (PCO2) and concentrations of bicarbonate, carbonate and total CO2 (CCO2). During night emersion periods, water PO2 decreased to almost zero in a few hours, pH fell, TA rose and PCO2 increased up to 1-3 Torr. During day emersion periods, water PO2 rose to 400-600 Torr, pH increased to more than 10, TA decreased substantially and PCO2 fell as low as 10(-4) Torr. The direction of the observed changes depended essentially on the illumination, indicating that respiratory and photosynthetic activities were the main processes involved. The large variations of the components of the carbonate system imply considerable changes of the CO2 capacitance coefficient in water, mainly during the day-time emersion. These changes are discussed in relation to the respiratory and acid-base physiology of the animals living in these biotopes.

Phase development in the Bi 2Sr 2CaCu 2O y system . Effects of oxygen pressure

NASA Astrophysics Data System (ADS)

List, F. A.; Hsu, H.; Cavin, O. B.; Porter, W. D.; Hubbard, C. R.; Kroeger, D. M.

1992-11-01

Studies have been undertaken using thermal analysis, in conjunction with high-temperature and room temperature X-ray diffraction, fraction, to elucidate phase relationships during thermal processing of thick films of initially phase pure Bi 2Sr 2CaCu 2O y (2212) on silver substrates in various oxygen-containing atmospheres (0.001 to 100% O 2). Exothermic events on cooling at 10°C/min from a partially liquid state vary with oxygen partial pressure and can be grouped into three sets (I-III). Set I is prominent for 0.001% and 0.1% O 2 in the range of 740-775°C and is believed to be associated with the crystallization of a Cu-free ∼ Bi 5Sr 3Ca 1 oxide phase. Set II results from the crystallization of 2212; it is observed for p(O 2)≥1.0% in the temperature range 800-870°C. Set III appears for 21% and 100% O 2 in the temperature range 880-910°C, and its origin is not clear from the results of this study. Subsequent room temperature X-ray diffraction from these samples suggests that in general high oxygen partial pressures (100% O 2) tend to favor the formation of Bi 2Sr 2CuO 6 (2201), whereas low oxygen partial pressures (0.001-0.1% O 2) lead to the formation of a Cu-free, Bi-Sr-Ca oxide phase. The 2212 phase forms at this cooling rate predominantly for intermediate oxygen partial pressures (7.6-21% O 2). High-temperature X-ray diffraction during cooling (2°C/h) from the partially liquid state shows a pronounced dependence of the order of evolution of crystalline 2212 and 2201 phases on p(O 2). For an oxygen partial pressure of 1.0% the formation of 2212 precedes that of 2201, whereas for 0.01% O 2 2201 crystallizes at a higher temperature than 2212. The implications of these results pertaining to thermal processing of thick 2212 films are discussed.

Persistent Currents in a Rotating Superleak Partially Filled with Superfluid Helium.

DTIC Science & Technology

1982-12-01

the difference in pressure of the helium bath Po and the reduced vapor pressure in the cell P. In the region from 1.0 to 0.1 the log Po-P has been seen...easily measurable quantities of temperature, T, the helium bath pressure, Po, and the cell pressure P to the film thickness d. Alpha is a measure of the...rotation is controlled by a motor and power supply. The temperature is controlled by the pumping rate and a feedback heater in the helium bath and -maybe

Critical hematocrit and oxygen partial pressure in the beating heart of pigs.

PubMed

Hiebl, B; Mrowietz, C; Ploetze, K; Matschke, K; Jung, F

2010-12-01

In cardiac surgery the substitution of lost blood volume by plasma substitutes is a common therapeutical approach. None of the currently available blood substitutes has a sufficient oxygen transport capacity. This can limit the functional integrity of the myocardium known as highly oxygen consumptive. The study was aimed to get information about the minimal hematocrit, also known as critical hematocrit (cHct), which guarantees a stable and adequate oxygen partial pressure in the myocardium (pO2). In adult female pigs (n=7) the hematocrit was reduced by isovolemic blood dilution with an intravenous infusion of isotonic 4% gelatine polysuccinate solution, The substituted blood volume ranged between 3000ml and 7780ml (mean: 5254±1672ml). In all animals the pO2 of the myocardium of the beating heart and of the resting skeletal muscle increased until blood dilution resulted in a Hct decrease down to 15%. Further blood dilution resulted in a decrease of the pO2. Only after the Hct was <10% the pO2 was lower than before blood dilution and accompanied by a lethal ischemia of the myocardium. These data indicate a cHct of about 10% in the pig animal model. Copyright © 2010 Elsevier Inc. All rights reserved.

Microenvironmental oxygen partial pressure in acute myeloid leukemia: Is there really a role for hypoxia?

PubMed

Rieger, Christina T; Fiegl, Michael

2016-07-01

Reduced oxygen partial pressure (pO2) has been recognized as being relevant in hematopoiesis and the pathophysiology of malignant diseases. Although hypoxic (meaning insufficient supply of oxygen) and anoxic areas are present and of pathophysiologic importance (by hypoxia-induced pathways such as HiF1α) in solid tumors, this may not be true for (malignant) hematologic cells. Hematopoiesis occurs in the stem cell niche, which is characterized, among other things, by extremely low pO2. However, in contrast to solid tumors, in this context, the low pO2 is physiological and this feature, among others, is shared by the malignant stem cell niche harboring leukemia-initiating cells. Upon differentiation, hematopoietic cells are constantly exposed to changes in pO2 as they travel throughout the human body and encounter arterial and venous blood and migrate into oxygen-carrier-free tissue with low pO2. Hematologic malignancies such as acute myeloid leukemia (AML) make little difference in this respect and, whereas low oxygen is the usual environment of AML cells, recent evidence suggests no role for real hypoxia. Although there is no evidence that AML pathophysiology is related to hypoxia, leukemic blasts still show several distinct biological features when exposed to reduced pO2: they down- or upregulate membrane receptors such as CXCR4 or FLT3, activate or inhibit intracellular signaling pathways such as PI3K, and specifically secrete cytokines (IL-8). In summary, reduced pO2 should not be mistaken for hypoxia (nor should it be so called), and it does not automatically induce hypoxia-response mechanisms; therefore, a strict distinction should be made between physiologically low pO2 (physoxia) and hypoxia. Copyright © 2016 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

Approximate Simulation of Acute Hypobaric Hypoxia with Normobaric Hypoxia

NASA Technical Reports Server (NTRS)

Conkin, J.; Wessel, J. H., III

2011-01-01

INTRODUCTION. Some manufacturers of reduced oxygen (O2) breathing devices claim a comparable hypobaric hypoxia (HH) training experience by providing F(sub I) O2 < 0.209 at or near sea level pressure to match the ambient O2 partial pressure (iso-pO2) of the target altitude. METHODS. Literature from investigators and manufacturers indicate that these devices may not properly account for the 47 mmHg of water vapor partial pressure that reduces the inspired partial pressure of O2 (P(sub I) O2). Nor do they account for the complex reality of alveolar gas composition as defined by the Alveolar Gas Equation. In essence, by providing iso-pO2 conditions for normobaric hypoxia (NH) as for HH exposures the devices ignore P(sub A)O2 and P(sub A)CO2 as more direct agents to induce signs and symptoms of hypoxia during acute training exposures. RESULTS. There is not a sufficient integrated physiological understanding of the determinants of P(sub A)O2 and P(sub A)CO2 under acute NH and HH given the same hypoxic pO2 to claim a device that provides isohypoxia. Isohypoxia is defined as the same distribution of hypoxia signs and symptoms under any circumstances of equivalent hypoxic dose, and hypoxic pO2 is an incomplete hypoxic dose. Some devices that claim an equivalent HH experience under NH conditions significantly overestimate the HH condition, especially when simulating altitudes above 10,000 feet (3,048 m). CONCLUSIONS. At best, the claim should be that the devices provide an approximate HH experience since they only duplicate the ambient pO2 at sea level as at altitude (iso-pO2 machines). An approach to reduce the overestimation is to at least provide machines that create the same P(sub I)O2 (iso-P(sub I)O2 machines) conditions at sea level as at the target altitude, a simple software upgrade.

Prevention of Hypoxemia During Apnea Testing: A Comparison of Oxygen Insufflation And Continuous Positive Airway Pressure.

PubMed

Kramer, Andreas H; Couillard, Philippe; Bader, Ryan; Dhillon, Peter; Kutsogiannis, Demetrios J; Doig, Christopher J

2017-08-01

Apnea testing is an essential step in the clinical diagnosis of brain death. Current international guidelines recommend placement of an oxygen (O 2 ) insufflation catheter into the endotracheal tube to prevent hypoxemia, but use of a continuous positive airway pressure (CPAP) valve may be more effective at limiting arterial partial pressure of O 2 (PO 2 ) reduction. We performed a multicenter study assessing consecutive apnea tests in 14 intensive care units (ICUs) in two cities utilizing differing protocols. In one city, O 2 catheters are placed and arterial blood gases (ABGs) performed at intervals determined by the attending physician. In the other city, a resuscitation bag with CPAP valve is attached to the endotracheal tube, and ABGs performed every 3-5 min. We assessed arterial PO 2 , partial pressure of carbon dioxide (PCO 2 ), pH, and blood pressure at the beginning and termination of each apnea test. Thirty-six apnea tests were performed using an O 2 catheter and 50 with a CPAP valve. One test per group was aborted because of physiological instability. There were no significant differences in the degree of PO 2 reduction (-59 vs. -32 mmHg, p = 0.72), rate of PCO 2 rise (3.2 vs. 3.9 mmHg per min, p = 0.22), or pH decline (-0.02 vs. -0.03 per min, p = 0.06). Performance of ABGs at regular intervals was associated with shorter test duration (10 vs. 7 min, p < 0.0001), smaller PCO 2 rise (30 vs. 26 mmHg, p = 0.0007), and less pH reduction (-0.20 vs. -0.17, p = 0.0012). Lower pH at completion of the apnea test was associated with greater blood pressure decline (p = 0.006). Both methods of O 2 supplementation are associated with similar changes in arterial PO 2 and PCO 2 . Performance of ABGs at regular intervals shortens apnea test duration and may avoid excessive pH reduction and consequent hemodynamic effects.

Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear

PubMed Central

Del Castillo, Luis F.; da Silva, Ana R. Ferreira; Hernández, Saul I.; Aguilella, M.; Andrio, Andreu; Mollá, Sergio; Compañ, Vicente

2014-01-01

Purpose We present an analysis of the corneal oxygen consumption Qc from non-linear models, using data of oxygen partial pressure or tension (pO2) obtained from in vivo estimation previously reported by other authors.1 Methods Assuming that the cornea is a single homogeneous layer, the oxygen permeability through the cornea will be the same regardless of the type of lens that is available on it. The obtention of the real value of the maximum oxygen consumption rate Qc,max is very important because this parameter is directly related with the gradient pressure profile into the cornea and moreover, the real corneal oxygen consumption is influenced by both anterior and posterior oxygen fluxes. Results Our calculations give different values for the maximum oxygen consumption rate Qc,max, when different oxygen pressure values (high and low pO2) are considered at the interface cornea-tears film. Conclusion Present results are relevant for the calculation on the partial pressure of oxygen, available at different depths into the corneal tissue behind contact lenses of different oxygen transmissibility. PMID:25649636

Neonatal oxidative stress depends on oxygen blood pressure in umbilical artery.

PubMed

Proietti, F; De Bernardo, G; Longini, M; Sordino, D; Scaramuzzini, G; Tataranno, M L; Belvisi, E; Bazzini, F; Perrone, S; Buonocore, G

2016-01-01

With advancing gestation, partial pressure of oxygen (pO2) and pH fall significantly. Hypoxia is a main factor inducing free radical generation and thereby oxidative stress (OS). Placental and fetal tissue response when oxygen becomes restricted is complex and partially known. We tested the hypothesis that changes in umbilical artery and vein blood gas concentrations modulate OS occurrence in the newborn. Seventy umbilical artery and vein plasma samples were collected from healthy term newborns immediately after delivery. F2 Isoprostanes (F2-Isop) were measured in all samples as reliable markers of lipid peroxidation. Significantly lower pCO2 and higher pO2 and pH were found in umbilical vein than in artery, as expected. A positive correlation was detected between pH and pO2 only in umbilical artery (p=0.019). F2-Isop levels were no different between artery and vein in cord blood. Significant correlations were found between F2-Isop and pCO2 (p=0.025) as well as between F2-Isop and pH in umbilical vein (p=0.027). F2-Isop correlated with pCO2 (p=0.007) as well as with pO2 values (p=0.005) in umbilical artery blood. Oxidative stress (OS) in newborns depends on oxygen concentrations in umbilical artery. OS biomarkers significantly correlate with pO2 and in umbilical artery but not in umbilical vein. In normoxic conditions fetal-maternal gas exchanges occurring in placenta re-establish normal higher oxygen levels in umbilical vein than artery, with a normal production of free radicals without any deleterious effects.

Effect of oxygen partial pressure on superconducting properties of Bi-2212/Ag tapes prepared by doctor-blade method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inoue, N.; Okada, M.; Higashiyama, K.

1997-06-01

The authors have investigated the relationship between oxygen partial pressure (P{sub O{sub 2}}) during the partial-melting process and superconducting properties for doctor-blade processed Bi-2212/Ag tapes. Tapes were heat-treated at various P{sub O{sub 2}} value of 0.01-1.00 atm. The DTA results for the doctor-blade tapes showed the melting point of the oxide rose with increasing P{sub O{sub 2}}. Correspondingly, the optimum heat-treatment temperature also increased with increasing P{sub O{sub 2}}. The tapes at P{sub O{sub 2}}=1.00 atm had the highest J{sub c} values of over 10{sup 5} A/cm{sup 2} at conditions of 4.2K, 10T, and their a.c. susceptibility showed a sharpmore » transition indicating improved intergrain coupling. Examination of cross sections for tapes melted above 0.20atm PO{sub 2} showed the good crystal alignment. From these results, it was concluded that processing at high PO{sub 2} was an effective method to obtain good superconducting properties for doctor-blade tapes.« less

Influence of polymeric microspheres on the myocardial oxygen partial pressure in the beating heart of pigs.

PubMed

Hiebl, B; Mrowietz, C; Lee, S; Braune, S; Knaut, M; Lendlein, A; Franke, R P; Jung, F

2011-07-01

Injection of labeled microspheres is an established method in animal models to analyze the capillary organ blood flow at different time points. However, the microspheres can lead to stenoses of the capillary lumen, which might affect tissue oxygen supply. Our study aimed to investigate the influence of repeated injections of microspheres into the left coronary artery on the tissue oxygen partial pressure (pO(2)) in the downstream supplied myocardium of Göttingen minipigs. Tests (n=6 pigs each) were performed with two differently sized microspheres (ø=10 ± 0.1 μm (M10) or ø=15 ± 0.15 μm (M15)) from polystyrene. The pO(2) was measured in the midmyocardium of the left and right ventricle for 6 min continuously after each of five injections (1 × 10(6) microspheres each). There was a time laps of 12 min between each injection. In addition, the influence of the carrier solution was analyzed solely in the identical time frame. pO(2) decreased significantly in the myocardial area supplied by the ramus interventricularis paraconalis after injection of M15 microspheres. In contrast, the application of the M10 microspheres did not change the myocardial pO(2). This finding suggests to use microspheres with diameters not exceeding 10 μm for the coronary blood flow assessment. Copyright © 2011 Elsevier Inc. All rights reserved.

Gd Ba Cu O bulk superconductors fabricated by a seeded infiltration growth technique under reduced oxygen partial pressure

NASA Astrophysics Data System (ADS)

Iida, K.; Babu, N. H.; Shi, Y. H.; Cardwell, D. A.; Murakami, M.

2006-06-01

Single-grain Gd-Ba-Cu-O (GdBCO) bulk superconductors have been grown by a seeded infiltration and growth (SIG) technique under a 1% O2+N2 atmosphere using a generic MgO-doped Nd-Ba-Cu-O (MgO-NdBCO) seed placed on the sample surface at room temperature (the so-called the cold-seeding method). Partial melting of the MgO-NdBCO seeds fabricated in air under notionally identical thermal processing conditions, however, limited the reliability of this bulk GdBCO single-grain process. The observed seed decomposition is attributed to the dependence of the peritectic temperature Tp of MgO-doped Nd1+xBa2-xCu3Oy solid solution (MgO-doped Nd-123ss, where ss indicates solid solution) compounds on both oxygen partial pressure during the melt process and the level of solid solution (x). The peritectic decomposition temperature of MgO-doped Nd-123ss, with x ranging from 0 to 0.5 under p(O2) = 1.00 atm, was observed to remain constant at 1120 °C. Tp was observed to decrease linearly as a function of solid solution level, on the other hand, under oxygen partial pressures of both p(O2) = 0.21 and 0.01 atm. Based on these results, MgO-doped NdBCO seed crystals should be grown under reduced oxygen partial pressure in order to obtain a stable MgO-doped NdBCO seed crystal suitable for cold-seeding processes of large-grain (RE)BCO bulk superconductors (where RE is a rare earth element).

Simultaneous measurement of brain tissue oxygen partial pressure, temperature, and global oxygen consumption during hibernation, arousal, and euthermy in non-sedated and non-anesthetized Arctic ground squirrels.

PubMed

Ma, Yilong; Wu, Shufen

2008-09-30

This study reports an online temperature correction method for determining tissue oxygen partial pressure P(tO2) in the striatum and a novel simultaneous measurement of brain P(tO2) and temperature (T(brain)) in conjunction with global oxygen consumption V(O2) in non-sedated and non-anesthetized freely moving Arctic ground squirrels (AGS, Spermophilus parryii). This method fills an important research gap-the lack of a suitable method for physiologic studies of tissue P(O2) in hibernating or other cool-blooded species. P(tO2) in AGS brain during euthermy (21.22+/-2.06 mmHg) is significantly higher (P=0.016) than during hibernation (13.21+/-0.46 mmHg) suggests brain oxygenation in the striatum is normoxic during euthermy and hypoxic during hibernation. These results in P(tO2) are different from blood oxygen partial pressure P(aO2) in AGS, which are significantly lower during euthermy than during hibernation and are actually hypoxic during euthermy and normoxic during hibernation in our previous study. This intriguing difference between the P(O2) of brain tissue and blood during these two physiological states suggests that regional mechanisms in the brain play a role in maintaining tissue oxygenation and protect against hypoxia during hibernation.

Mapping oxygen concentration in the awake mouse brain

PubMed Central

Lyons, Declan G; Parpaleix, Alexandre; Roche, Morgane; Charpak, Serge

2016-01-01

Although critical for brain function, the physiological values of cerebral oxygen concentration have remained elusive because high-resolution measurements have only been performed during anesthesia, which affects two major parameters modulating tissue oxygenation: neuronal activity and blood flow. Using measurements of capillary erythrocyte-associated transients, fluctuations of oxygen partial pressure (Po2) associated with individual erythrocytes, to infer Po2 in the nearby neuropil, we report the first non-invasive micron-scale mapping of cerebral Po2 in awake, resting mice. Interstitial Po2 has similar values in the olfactory bulb glomerular layer and the somatosensory cortex, whereas there are large capillary hematocrit and erythrocyte flux differences. Awake tissue Po2 is about half that under isoflurane anesthesia, and within the cortex, vascular and interstitial Po2 values display layer-specific differences which dramatically contrast with those recorded under anesthesia. Our findings emphasize the importance of measuring energy parameters non-invasively in physiological conditions to precisely quantify and model brain metabolism. DOI: http://dx.doi.org/10.7554/eLife.12024.001 PMID:26836304

Mapping oxygen concentration in the awake mouse brain.

PubMed

Lyons, Declan G; Parpaleix, Alexandre; Roche, Morgane; Charpak, Serge

2016-02-02

Although critical for brain function, the physiological values of cerebral oxygen concentration have remained elusive because high-resolution measurements have only been performed during anesthesia, which affects two major parameters modulating tissue oxygenation: neuronal activity and blood flow. Using measurements of capillary erythrocyte-associated transients, fluctuations of oxygen partial pressure (Po2) associated with individual erythrocytes, to infer Po2 in the nearby neuropil, we report the first non-invasive micron-scale mapping of cerebral Po2 in awake, resting mice. Interstitial Po2 has similar values in the olfactory bulb glomerular layer and the somatosensory cortex, whereas there are large capillary hematocrit and erythrocyte flux differences. Awake tissue Po2 is about half that under isoflurane anesthesia, and within the cortex, vascular and interstitial Po2 values display layer-specific differences which dramatically contrast with those recorded under anesthesia. Our findings emphasize the importance of measuring energy parameters non-invasively in physiological conditions to precisely quantify and model brain metabolism.

Growth of the microalgae Neochloris oleoabundans at high partial oxygen pressures and sub-saturating light intensity.

PubMed

Sousa, Cláudia; de Winter, Lenneke; Janssen, Marcel; Vermuë, Marian H; Wijffels, René H

2012-01-01

The effect of partial oxygen pressure on growth of Neochloris oleoabundans was studied at sub-saturating light intensity in a fully-controlled stirred tank photobioreactor. At the three partial oxygen pressures tested (P(O)₂= 0.24; 0.63; 0.84 bar), the specific growth rate was 1.38; 1.36 and 1.06 day(-1), respectively. An increase of the P(CO)₂from 0.007 to 0.02 bar at P(O₂) of 0.84 bar resulted in an increase in the growth rate from 1.06 to 1.36 day(-1). These results confirm that the reduction of algal growth at high oxygen concentrations at sub-saturating light conditions is mainly caused by competitive inhibition of Rubisco. This negative effect on growth can be overcome by restoring the O(2)/CO(2) ratio by an increase in the partial carbon dioxide pressure. In comparison to general practice (P(O(2)) = 0.42 bar), working at partial O(2) pressure of 0.84 bar could reduce the energy requirement for degassing by a factor of 3-4. Copyright © 2011 Elsevier Ltd. All rights reserved.

Electronic Conductivity of Doped-Lanthanum Gallate Electrolytes

NASA Astrophysics Data System (ADS)

Yamaji, Katsuhiko; Xiong, Yue Ping; Kishimoto, Haruo; Horita, Teruhisa; Sakai, Natsuko; Brito, Manuel E.; Yokokawa, Harumi

Electronic conductivity of doped lanthanum gallate electrolytes were determined by using a Hebb-Wagner type polarization cell. Electronic conductivity of cobalt-doped, La0.8Sr0.2Ga0.8Mg0.15Co0.5O3-δ (LSGMC), and non cobalt-doped, La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM8282), were measured as a function of oxygen partial pressures. The electronic conductivity of LSGM8282 showed a linear dependence on p(O2)1/4 in the higher p(O2) region, which is attributed to the electronic hole conductivity. The electronic conductivity of LSGMC showed a linear dependence on p(O2)1/6 in the higher p(O2) region. LSGMC has higher electronic conductivity than LSGM, and the conductivity was not clearly changed with temperatures between 600 and 800 °C. In lower p(O2) region, the electronic conductivity data have poor reproducibility and did not show any dependence on p(O2) because of the degradation of the electrolytes in severe reducing atmospheres.

Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear.

PubMed

Del Castillo, Luis F; da Silva, Ana R Ferreira; Hernández, Saul I; Aguilella, M; Andrio, Andreu; Mollá, Sergio; Compañ, Vicente

2015-01-01

We present an analysis of the corneal oxygen consumption Qc from non-linear models, using data of oxygen partial pressure or tension (P(O2) ) obtained from in vivo estimation previously reported by other authors. (1) METHODS: Assuming that the cornea is a single homogeneous layer, the oxygen permeability through the cornea will be the same regardless of the type of lens that is available on it. The obtention of the real value of the maximum oxygen consumption rate Qc,max is very important because this parameter is directly related with the gradient pressure profile into the cornea and moreover, the real corneal oxygen consumption is influenced by both anterior and posterior oxygen fluxes. Our calculations give different values for the maximum oxygen consumption rate Qc,max, when different oxygen pressure values (high and low P(O2)) are considered at the interface cornea-tears film. Present results are relevant for the calculation on the partial pressure of oxygen, available at different depths into the corneal tissue behind contact lenses of different oxygen transmissibility. Copyright © 2014. Published by Elsevier Espana.

Multi Frequency Phase Fluorimetry (MFPF) for Oxygen Partial Pressure Measurement: Ex Vivo Validation by Polarographic Clark-Type Electrode

PubMed Central

Boehme, Stefan; Duenges, Bastian; Klein, Klaus U.; Hartwich, Volker; Mayr, Beate; Consiglio, Jolanda; Baumgardner, James E.; Markstaller, Klaus; Basciani, Reto; Vogt, Andreas

2013-01-01

Background Measurement of partial pressure of oxygen (PO2) at high temporal resolution remains a technological challenge. This study introduces a novel PO2 sensing technology based on Multi-Frequency Phase Fluorimetry (MFPF). The aim was to validate MFPF against polarographic Clark-type electrode (CTE) PO2 measurements. Methodology/Principal Findings MFPF technology was first investigated in N = 8 anaesthetised pigs at FIO2 of 0.21, 0.4, 0.6, 0.8 and 1.0. At each FIO2 level, blood samples were withdrawn and PO2 was measured in vitro with MFPF using two FOXY-AL300 probes immediately followed by CTE measurement. Secondly, MFPF-PO2 readings were compared to CTE in an artificial circulatory setup (human packed red blood cells, haematocrit of 30%). The impacts of temperature (20, 30, 40°C) and blood flow (0.8, 1.6, 2.4, 3.2, 4.0 L min−1) on MFPF-PO2 measurements were assessed. MFPF response time in the gas- and blood-phase was determined. Porcine MFPF-PO2 ranged from 63 to 749 mmHg; the corresponding CTE samples from 43 to 712 mmHg. Linear regression: CTE = 15.59+1.18*MFPF (R2 = 0.93; P<0.0001). Bland Altman analysis: meandiff 69.2 mmHg, rangediff -50.1/215.6 mmHg, 1.96-SD limits -56.3/194.8 mmHg. In artificial circulatory setup, MFPF-PO2 ranged from 20 to 567 mmHg and CTE samples from 11 to 575 mmHg. Linear regression: CTE = −8.73+1.05*MFPF (R2 = 0.99; P<0.0001). Bland-Altman analysis: meandiff 6.6 mmHg, rangediff -9.7/20.5 mmHg, 1.96-SD limits -12.7/25.8 mmHg. Differences between MFPF and CTE-PO2 due to variations of temperature were less than 6 mmHg (range 0–140 mmHg) and less than 35 mmHg (range 140–750 mmHg); differences due to variations in blood flow were less than 15 mmHg (all P-values>0.05). MFPF response-time (monoexponential) was 1.48±0.26 s for the gas-phase and 1.51±0.20 s for the blood-phase. Conclusions/Significance MFPF-derived PO2 readings were reproducible and showed excellent correlation and good agreement with Clark-type electrode-based PO2 measurements. There was no relevant impact of temperature and blood flow upon MFPF-PO2 measurements. The response time of the MFPF FOXY-AL300 probe was adequate for real-time sensing in the blood phase. PMID:23565259

Multi frequency phase fluorimetry (MFPF) for oxygen partial pressure measurement: ex vivo validation by polarographic clark-type electrode.

PubMed

Boehme, Stefan; Duenges, Bastian; Klein, Klaus U; Hartwich, Volker; Mayr, Beate; Consiglio, Jolanda; Baumgardner, James E; Markstaller, Klaus; Basciani, Reto; Vogt, Andreas

2013-01-01

Measurement of partial pressure of oxygen (PO2) at high temporal resolution remains a technological challenge. This study introduces a novel PO2 sensing technology based on Multi-Frequency Phase Fluorimetry (MFPF). The aim was to validate MFPF against polarographic Clark-type electrode (CTE) PO2 measurements. MFPF technology was first investigated in N = 8 anaesthetised pigs at FIO2 of 0.21, 0.4, 0.6, 0.8 and 1.0. At each FIO2 level, blood samples were withdrawn and PO2 was measured in vitro with MFPF using two FOXY-AL300 probes immediately followed by CTE measurement. Secondly, MFPF-PO2 readings were compared to CTE in an artificial circulatory setup (human packed red blood cells, haematocrit of 30%). The impacts of temperature (20, 30, 40°C) and blood flow (0.8, 1.6, 2.4, 3.2, 4.0 L min(-1)) on MFPF-PO2 measurements were assessed. MFPF response time in the gas- and blood-phase was determined. Porcine MFPF-PO2 ranged from 63 to 749 mmHg; the corresponding CTE samples from 43 to 712 mmHg. Linear regression: CTE = 15.59+1.18*MFPF (R(2) = 0.93; P<0.0001). Bland Altman analysis: meandiff 69.2 mmHg, rangediff -50.1/215.6 mmHg, 1.96-SD limits -56.3/194.8 mmHg. In artificial circulatory setup, MFPF-PO2 ranged from 20 to 567 mmHg and CTE samples from 11 to 575 mmHg. Linear regression: CTE = -8.73+1.05*MFPF (R(2) = 0.99; P<0.0001). Bland-Altman analysis: meandiff 6.6 mmHg, rangediff -9.7/20.5 mmHg, 1.96-SD limits -12.7/25.8 mmHg. Differences between MFPF and CTE-PO2 due to variations of temperature were less than 6 mmHg (range 0-140 mmHg) and less than 35 mmHg (range 140-750 mmHg); differences due to variations in blood flow were less than 15 mmHg (all P-values>0.05). MFPF response-time (monoexponential) was 1.48±0.26 s for the gas-phase and 1.51±0.20 s for the blood-phase. MFPF-derived PO2 readings were reproducible and showed excellent correlation and good agreement with Clark-type electrode-based PO2 measurements. There was no relevant impact of temperature and blood flow upon MFPF-PO2 measurements. The response time of the MFPF FOXY-AL300 probe was adequate for real-time sensing in the blood phase.

[The effect of altered oxygen partial pressure on the resisitance to hypoxia and expression of oxygen-sensitive genes in Drosophila melanogaster].

PubMed

Berezovs'kyĭ, V Ia; Chaka, O H; Litovka, I H; Levashov, M I; Ianko, R V

2014-01-01

As a result of resistance test to hypoxia of Drosophilas melanogaster of Oregon strain, we identified a high resistance (Group II) and low resistance (Group III) subpopulations of flies. Flies from groups II and III were incubated in a constant normobaric hypoxia (Po2=62-64 mm Hg) for 10 generations. A highly resistant group (Group IV) were exposed to a shortterm anoxia (Po,=1,5 mm Hg, 5 min) every generation. Larvae from Groups II, III, and IV demonstrated significantly elevated levels of Sir and CG 14740 expression. Larvae from Group II had a significantly higher expression of CG 14740 compared to group III. The restitution time after exposure to anoxia was significantly reduced in Group II (on 31% of the control values) Our results suggest that long-term adaptation to low oxygen partial pressure of highly resistant Drosophila significantly reduces the time of restitution and increases the expression of Sir2 and CG14740 genes.

Oxygen Toxicity and Special Operations Forces Diving: Hidden and Dangerous

PubMed Central

Wingelaar, Thijs T.; van Ooij, Pieter-Jan A. M.; van Hulst, Rob A.

2017-01-01

In Special Operations Forces (SOF) closed-circuit rebreathers with 100% oxygen are commonly utilized for covert diving operations. Exposure to high partial pressures of oxygen (PO2) could cause damage to the central nervous system (CNS) and pulmonary system. Longer exposure time and higher PO2 leads to faster development of more serious pathology. Exposure to a PO2 above 1.4 ATA can cause CNS toxicity, leading to a wide range of neurologic complaints including convulsions. Pulmonary oxygen toxicity develops over time when exposed to a PO2 above 0.5 ATA and can lead to inflammation and fibrosis of lung tissue. Oxygen can also be toxic for the ocular system and may have systemic effects on the inflammatory system. Moreover, some of the effects of oxygen toxicity are irreversible. This paper describes the pathophysiology, epidemiology, signs and symptoms, risk factors and prediction models of oxygen toxicity, and their limitations on SOF diving. PMID:28790955

Redifferentiation of dedifferentiated bovine articular chondrocytes enhanced by cyclic hydrostatic pressure under a gas-controlled system.

PubMed

Kawanishi, Makoto; Oura, Atsuhiro; Furukawa, Katsuko; Fukubayashi, Toru; Nakamura, Kozo; Tateishi, Tetsuya; Ushida, Takashi

2007-05-01

Hydrostatic pressure is one of the most frequently used mechanical stimuli in chondrocyte experiments. A variety of hydrostatic pressure loading devices have been used in cartilage cell experiments. However, no gas-controlled system with other than a low pressure load was used up to this time. Hence we used a polyolefin bag from which gas penetration was confirmed. Chondrocytes were extracted from bovine normal knee joint cartilage. After 3 passages, dedifferentiated chondrocytes were applied to form a pellet. These pellets were cultured in chemically defined serum-free medium with ITS+Premix for 3 days. Then 5 MPa of cyclic hydrostatic pressure was applied at 0.5 Hz for 4 h per day for 4 days. Semiquantitative reverse transcriptase-polymerase chain reaction showed a 5-fold increase in the levels of aggrecan mRNA due to cyclic hydrostatic pressure load (p<0.01). Type II collagen mRNA levels were also upregulated 4-fold by a cyclic hydrostatic pressure load (p<0.01). Type I collagen mRNA levels were similarly reduced in the cyclic hydrostatic pressure load group and in the control group. The partial oxygen pressure (PO2) and partial carbon dioxide pressure (PCO2) of the medium in the bag reached equilibrium in 24 h, and no significant change was observed for 3 days afterwards. PO2 and PCO2 were very well controlled. The loaded pellet showed better safranin O/fast green staining than did the control pellet. Metachromatic staining by Alcian blue staining was found to be stronger in the loaded than in the control pellets. The extracellular matrices excretion of loaded pellets was higher than that of control pellets. These results suggest that gas-controlled cyclic hydrostatic pressure enhanced the cartilaginous matrix formation of dedifferentiated cells differentiated in vitro.

Effects of increased inspired oxygen concentration on tissue oxygenation: theoretical considerations.

PubMed

Lumb, Andrew B; Nair, Sindhu

2010-03-01

Breathing increased fractional oxygen concentration (FiO2) is recommended for the treatment of tissue ischaemia. The theoretical benefits of increasing FiO2 on tissue oxygenation were evaluated using standard physiological equations. Assuming constant oxygen consumption by tissues throughout the length of a capillary, the oxygen content at 20 arbitrary points along a capillary was calculated. Using mathematical representations of the haemoglobin dissociation curve and an iterative approach to include the dissolved oxygen component of oxygen content, the oxygen partial pressure (PO2) profile along a capillary was estimated. High FiO2 concentrations cause large increases in PO2 at the arteriolar end of capillaries but these large PO2 values, caused by the extra dissolved oxygen, rapidly decline along the capillary. At the venular end of the capillary (the area of tissue most likely to be hypoxic), breathing oxygen causes only a modest improvement in PO2. Increasing FiO2 to treat tissue hypoxia has clear benefits, but a multimodal approach to management is required.

Estimates of atmospheric O2 in the Paleoproterozoic from paleosols

NASA Astrophysics Data System (ADS)

Kanzaki, Yoshiki; Murakami, Takashi

2016-02-01

A weathering model was developed to constrain the partial pressure of atmospheric O2 (PO2) in the Paleoproterozoic from the Fe records in paleosols. The model describes the Fe behavior in a weathering profile by dissolution/precipitation of Fe-bearing minerals, oxidation of dissolved Fe(II) to Fe(III) by oxygen and transport of dissolved Fe by water flow, in steady state. The model calculates the ratio of the precipitated Fe(III)-(oxyhydr)oxides from the dissolved Fe(II) to the dissolved Fe(II) during weathering (ϕ), as a function of PO2 . An advanced kinetic expression for Fe(II) oxidation by O2 was introduced into the model from the literature to calculate accurate ϕ-PO2 relationships. The model's validity is supported by the consistency of the calculated ϕ-PO2 relationships with those in the literature. The model can calculate PO2 for a given paleosol, once a ϕ value and values of the other parameters relevant to weathering, namely, pH of porewater, partial pressure of carbon dioxide (PCO2), water flow, temperature and O2 diffusion into soil, are obtained for the paleosol. The above weathering-relevant parameters were scrutinized for individual Paleoproterozoic paleosols. The values of ϕ, temperature, pH and PCO2 were obtained from the literature on the Paleoproterozoic paleosols. The parameter value of water flow was constrained for each paleosol from the mass balance of Si between water and rock phases and the relationships between water saturation ratio and hydraulic conductivity. The parameter value of O2 diffusion into soil was calculated for each paleosol based on the equation for soil O2 concentration with the O2 transport parameters in the literature. Then, we conducted comprehensive PO2 calculations for individual Paleoproterozoic paleosols which reflect all uncertainties in the weathering-relevant parameters. Consequently, robust estimates of PO2 in the Paleoproterozoic were obtained: 10-7.1-10-5.4 atm at ∼2.46 Ga, 10-5.0-10-2.5 atm at ∼2.15 Ga, 10-5.2-10-1.7 atm at ∼2.08 Ga and more than 10-4.6-10-2.0 atm at ∼1.85 Ga. Comparison of the present PO2 estimates to those in the literature suggests that a drastic rise of oxygen would not have occurred at ∼2.4 Ga, supporting a slightly rapid rise of oxygen at ∼2.4 Ga and a gradual rise of oxygen in the Paleoproterozoic in long term.

Experimental petrology and origin of rocks from the Descartes Highlands

NASA Technical Reports Server (NTRS)

Walker, D.; Longhi, J.; Grove, T. L.; Stolper, E.; Hays, J. F.

1973-01-01

Petrographic studies of Apollo 16 samples indicate that rocks 62295 and 68415 are crystallization products of highly aluminous melts. 60025 is a shocked, crushed and partially annealed plagioclase cumulate. 60315 is a recrystallized noritic breccia of disputed origin. 60335 is a feldspathic basalt filled with xenoliths and xenocrysts of anorthosite, breccia, and anorthite. The Fe/(Fe+Mg) of plagioclase appears to be a relative crystallization index. Low pressure melting experiments with controlled Po2 indicate that the igneous samples crystallized at oxygen fugacities well below the Fe/FeO buffer. Crystallization experiments at various pressures suggest that the 62295 and 68415 compositions were produced by partial or complete melting of lunar crustal materials, and not by partial melting of the deep lunar interior.

Residual oxygen time model for oxygen partial pressure near 130 kPa (1.3 atm).

PubMed

Shykoff, Barbara E

2015-01-01

A two-part residual oxygen time model predicts the probability of detectible pulmonary oxygen toxicity P(P[O2tox]) after dives with oxygen partial pressure (PO2) approximately 130 kPa, and provides a tool to plan dive series with selected risk of P[O2tox]. Data suggest that pulmonary oxygen injury at this PO2 is additive between dives. Recovery begins after a delay and continues during any following dive. A logistic relation expresses P(P[O2tox]) as a function of dive duration (T(dur)) [hours]: P(P[O2tox]) = 100/[1+exp (3.586-0.49 x T(dur))] This expression maps T(dur) to P(P[O2tox]) or, in the linear mid-portion of the curve, P(P[O2tox]) usefully to T(dur). For multiple dives or during recovery, it maps to an equivalent dive duration, T(eq). T(eq) was found after second dives of duration T(dur 2). Residual time from the first dive t(r) = T(eq) - T(dur2). With known t(r), t and T(dur) a recovery model was fitted. t(r) = T(dur) x exp [-k x((t-5)/T(dur)2], where t = t - 5 hours, k = 0.149 for resting, and 0.047 for exercising divers, and t represents time after surfacing. The fits were assessed for 1,352 man-dives. Standard deviations of the residuals were 8.5% and 18.3% probability for resting or exercise dives, respectively.

Modulation of network pacemaker neurons by oxygen at the anaerobic threshold.

PubMed

Hill, Andrew A V; Simmers, John; Meyrand, Pierre; Massabuau, Jean-Charles

2012-07-01

Previous in vitro and in vivo studies showed that the frequency of rhythmic pyloric network activity in the lobster is modulated directly by oxygen partial pressure (PO(2)). We have extended these results by (1) increasing the period of exposure to low PO(2) and by (2) testing the sensitivity of the pyloric network to changes in PO(2) that are within the narrow range normally experienced by the lobster (1 to 6 kPa). We found that the pyloric network rhythm was indeed altered by changes in PO(2) within the range typically observed in vivo. Furthermore, a previous study showed that the lateral pyloric constrictor motor neuron (LP) contributes to the O(2) sensitivity of the pyloric network. Here, we expanded on this idea by testing the hypothesis that pyloric pacemaker neurons also contribute to pyloric O(2) sensitivity. A 2-h exposure to 1 kPa PO(2), which was twice the period used previously, decreased the frequency of an isolated group of pacemaker neurons, suggesting that changes in the rhythmogenic properties of these cells contribute to pyloric O(2) sensitivity during long-term near-anaerobic (anaerobic threshold, 0.7-1.2 kPa) conditions.

[Simultaneous determination of oxygen partial pressure in the scala tympani, electrocochleography and blood pressure values in the guinea pig].

PubMed

Lamm, K; Lamm, C; Lamm, H; Schumann, K

1989-02-01

Nineteen guinea pigs were exposed to impulse noise from gunfire (G3 of the Federal German Army, 156 dB peak SPL), 6+6 shots or 12+6 shots, with a 3-s pulse interval. For simultaneous measurements of pO2, cochlea microphonics (CM) and compound action potentials of the auditory nerve (CAP), we used the thin 0.5 microns microcoaxial needle electrode described by Baumgaertl and Luebbers, which was placed through the roundwindow membrane into the scala tympani to a depth of 1000 microns. After exposure to the first 6 or 12 gunshots, the pO2 increased by about 20% of the original values in 12 guinea pigs (63%). In the following 30 min of recovery time the pO2 decreased, stabilized or showed a further decline. There were only 3 animals with a pO2 loss of 70% of the original values. Most animals showed a decline of 25% at the end of the recovery period. In all animals after 6 additional shots, the pO2 only decreased by another 5% of the original values. Amplitudes of CM and CAP were reduced by about 40% of the original values after 6 or 12 shots and by another 20%-24% (CM) and 5%-15% (CAP) after 6 additional shots. The intra-arterial blood pressure in the common carotid artery remained constant. The results are discussed with respect to the well-known morphological damage, subsequent ion imbalance and hypoxia within the cortilymph after exposure to gunfire. These changes are reflected in the loss of CMs and CAPs.

Secondary ion generation mechanism studied by ISS-SIMS and work function measurements

NASA Astrophysics Data System (ADS)

Kawatoh, Eizoh; Terada, Norihito; Shimizu, Ryuichi; Kang, Hee Jae

1989-03-01

Oxygen enhancement effects in secondary ion generation were studied in polycrystalline Ni at different partial pressures of oxygen, Po2, by sequential ISS-SIMS and work function measurements. The investigation has revealed that the enhancement undergoes three stages: (I) The secondary ion intensity increases monotonically with an increase of work function which is described very well by the electron tunneling model. (II) This tendency abruptly changes, i.e. the work function decreases and the secondary ion intensity increases rapidly, for a slight increase of Po2 (III) The secondary ion intensities gradually increase and become saturated with a further increase of Po2. It has also been found that the critical coverage, θc, corresponds exactly to the stage (II) behaviour, which was observed by Blaise and Bernheim for a single crystal (100)Ni surface.

The effects of centrally injected arachidonic acid on respiratory system: Involvement of cyclooxygenase to thromboxane signaling pathway.

PubMed

Erkan, Leman Gizem; Guvenc, Gokcen; Altinbas, Burcin; Niaz, Nasir; Yalcin, Murat

2016-05-01

Arachidonic acid (AA) is a polyunsaturated fatty acid that is present in the phospholipids of the cell membranes of the body and is abundant in the brain. Exogenously administered AA has been shown to affect brain metabolism and to exhibit cardiovascular and neuroendocrine actions. However, little is known regarding its respiratory actions and/or central mechanism of its respiratory effects. Therefore, the present study was designed to investigate the possible effects of centrally injected AA on respiratory system and the mediation of the central cyclooxygenase (COX) to thromboxane A2 (TXA2) signaling pathway on AA-induced respiratory effects in anaesthetized rats. Intracerebroventricular (i.c.v.) administration of AA induced dose- and time-dependent increase in tidal volume, respiratory rates and respiratory minute ventilation and also caused an increase in partial oxygen pressure (pO2) and decrease in partial carbon dioxide pressure (pCO2) in male anaesthetized Spraque Dawley rats. I.c.v. pretreatment with ibuprofen, a non-selective COX inhibitor, completely blocked the hyperventilation and blood gases changes induced by AA. In addition, central pretreatment with different doses of furegrelate, a TXA2 synthesis inhibitor, also partially prevented AA-evoked hyperventilation and blood gases effects. These data explicitly show that centrally administered AA induces hyperventilation with increasing pO2 and decreasing pCO2 levels which are mediated by the activation of central COX to TXA2 signaling pathway. Copyright © 2016 Elsevier B.V. All rights reserved.

Cerebral Oxygenation of the Cortex and Striatum following Normobaric Hyperoxia and Mild Hypoxia in Rats by EPR Oximetry using Multi-Probe Implantable Resonators

PubMed Central

Hou, Huagang; Li, Hongbin; Dong, Ruhong; Mupparaju, Sriram; Khan, Nadeem; Swartz, Harold

2013-01-01

Multi-site electron paramagnetic resonance (EPR) oximetry, using multi-probe implantable resonators, was used to measure the partial pressure of oxygen (pO2) in the brains of rats following normobaric hyperoxia and mild hypoxia. The cerebral tissue pO2 was measured simultaneously in the cerebral cortex and striatum in the same rats before, during, and after normobaric hyperoxia and mild hypoxia challenges. The baseline mean tissue pO2 values (±SE) were not significantly different between the cortex and striatum. During 30 min of 100% O2 inhalation, a statistically significant increase in tissue pO2 of all four sites was observed, however, the tissue pO2 of the striatum area was significantly higher than in the forelimb area of the cortex. Brain pO2 significantly decreased from the baseline value during 15 min of 15% O2 challenge. No differences in the recovery of the cerebral cortex and striatum pO2 were observed when the rats were allowed to breathe 30% O2. It appears that EPR oximetry using implantable resonators can provide information on pO2 under the experimental conditions needed for such a study. The levels of pO2 that occurred in these experiments are readily resolvable by multi-site EPR oximetry with multi-probe resonators. In addition, the ability to simultaneously measure the pO2 in several areas of the brain provides important information that could potentially help differentiate the pO2 changes that can occur due to global or local mechanisms. PMID:21445770

Temperature dependence of surface tension of molten iron under reducing gas atmosphere

NASA Astrophysics Data System (ADS)

Ozawa, S.; Takahashi, S.; Fukuyama, H.; Watanabe, M.

2011-12-01

Surface tension of molten iron was measured under Ar-He-5vol.%H2 gas by oscillating droplet method using electromagnetic levitation furnace in consideration of the temperature dependence of oxygen partial pressure, Po2, of the gas. For comparison, the measurement was carried under Ar-He atmosphere to fix the Po2 of the inlet gas at 10-2Pa. The surface tension was successfully measured over a wide temperature range of about 780K including undercooling condition. When Po2 is fixed at 10-2 Pa, the surface tension increased and then decreased with increasing temperature like a boomerang shape. When the measurement was carried out under the H2-containing gas atmosphere, the temperature dependence of the surface tension shows unique kink at around 1810K instead of liner relationship due to competition between the temperature dependence of the Po2 and that of the equilibrium constant of oxygen adsorption reaction. The relationship between the calculated lnKad with respect to inverse temperature using Szyszkowski model was different between the atmospheric gases.

Effects of single and combined Mycoplasma gallisepticum vaccinations on blood electrolytes and acid-base balance in commercial egg-laying hens.

PubMed

Olanrewaju, H A; Collier, S D; Branton, S L

2011-02-01

A previous study from our laboratory on F-strain Mycoplasma gallisepticum-inoculated layers showed a significant increase in arterial partial pressure of oxygen (pO(2)), which is generally associated with an oxygen-dependent improvement in tissue oxygenation. The aim of this study was to determine whether a killed (bacterin) and live TS-11-strain M. gallisepticum (TS-11-MG) vaccine treatment combination could further enhance the arterial pO(2) levels in layer chickens. The experiment was conducted in 2 trials and arranged in a completely randomized experimental design with 4 treatments. The treatments consisted of a control M. gallisepticum, bacterin, TS-11-MG, and bacterin + TS-11-MG combined, with all treatments receiving the R low strain of MG at 30 wk of age (WOA). In each of the 2 trials, 160 one-day-old MG-free pullets were raised to 10 WOA and were transported to a poultry disease isolation facility. Sixteen isolation units were divided into 4 treatment groups, and each of the 4 treatment groups had 4 replication units, with 10 birds/unit (40 birds/treatment). Venous blood samples were collected at the termination of the study at 56 WOA. The TS-11-MG-vaccinated chickens had a higher (P ≤ 0.05) blood pO(2) and a lower (P ≤ 0.05) partial pressure of CO(2) when compared with the control and combined MG-vaccinated groups. However, no significant blood pO(2) differences were observed between the bacterin and TS-11-MG treatment groups. Hematocrit and blood concentrations of hemoglobin were not statistically different among treatments, but were numerically higher in the TS-11-MG treatment group. There was a significant (P ≤ 0.05) treatment effect on blood concentrations of Na(+), Ca(2+), and anion, but no significant effect on glucose, cholesterol, triglyceride, or osmolality. These data suggest that the inoculation of layers with TS-11-MG was more effective in elevating pO(2) than was inoculation with TS-11-MG + bacterin combined.

Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve.

PubMed

Collins, Julie-Ann; Rudenski, Aram; Gibson, John; Howard, Luke; O'Driscoll, Ronan

2015-09-01

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (S O2 ) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin-oxygen dissociation curve, a graphical representation of the relationship between oxygen satur-ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the S O2 in blood from patients with normal pH and S O2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (S pO2 ) is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (S aO2 ) as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable S pO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Polarity inversion of AlN film grown on nitrided a-plane sapphire substrate with pulsed DC reactive sputtering

NASA Astrophysics Data System (ADS)

Noorprajuda, Marsetio; Ohtsuka, Makoto; Fukuyama, Hiroyuki

2018-04-01

The effect of oxygen partial pressure (PO2) on polarity and crystalline quality of AlN films grown on nitrided a-plane sapphire substrates by pulsed direct current (DC) reactive sputtering was investigated as a fundamental study. The polarity inversion of AlN from nitrogen (-c)-polarity to aluminum (+c)-polarity occurred during growth at a high PO2 of 9.4×103 Pa owing to Al-O octahedral formation at the interface of nitrided layer and AlN sputtered film which reset the polarity of AlN. The top part of the 1300 nm-thick AlN film sputtered at the high PO2 was polycrystallized. The crystalline quality was improved owing to the high kinetic energy of Al sputtered atom in the sputtering phenomena. Thinner AlN films were also fabricated at the high PO2 to eliminate the polycrystallization. For the 200 nm-thick AlN film sputtered at the high PO2, the full width at half-maximum values of the AlN (0002) and (10-12) X-ray diffraction rocking curves were 47 and 637 arcsec, respectively.

Vagus nerve stimulation mitigates intrinsic cardiac neuronal remodeling and cardiac hypertrophy induced by chronic pressure overload in guinea pig

PubMed Central

Beaumont, Eric; Wright, Gary L.; Southerland, Elizabeth M.; Li, Ying; Chui, Ray; KenKnight, Bruce H.; Armour, J. Andrew

2016-01-01

Our objective was to determine whether chronic vagus nerve stimulation (VNS) mitigates pressure overload (PO)-induced remodeling of the cardioneural interface. Guinea pigs (n = 48) were randomized to right or left cervical vagus (RCV or LCV) implant. After 2 wk, chronic left ventricular PO was induced by partial (15–20%) aortic constriction. Of the 31 animals surviving PO induction, 10 were randomized to RCV VNS, 9 to LCV VNS, and 12 to sham VNS. VNS was delivered at 20 Hz and 1.14 ± 0.03 mA at a 22% duty cycle. VNS commenced 10 days after PO induction and was maintained for 40 days. Time-matched controls (n = 9) were evaluated concurrently. Echocardiograms were obtained before and 50 days after PO. At termination, intracellular current-clamp recordings of intrinsic cardiac (IC) neurons were studied in vitro to determine effects of therapy on soma characteristics. Ventricular cardiomyocyte sizes were assessed with histology along with immunoblot analysis of selected proteins in myocardial tissue extracts. In sham-treated animals, PO increased cardiac output (34%, P < 0.004), as well as systolic (114%, P < 0.04) and diastolic (49%, P < 0.002) left ventricular volumes, a hemodynamic response prevented by VNS. PO-induced enhancements of IC synaptic efficacy and muscarinic sensitivity of IC neurons were mitigated by chronic VNS. Increased myocyte size, which doubled in PO (P < 0.05), was mitigated by RCV. PO hypertrophic myocardium displayed decreased glycogen synthase (GS) protein levels and accumulation of the phosphorylated (inactive) form of GS. These PO-induced changes in GS were moderated by left VNS. Chronic VNS targets IC neurons accompanying PO to obtund associated adverse cardiomyocyte remodeling. PMID:26993230

Vagus nerve stimulation mitigates intrinsic cardiac neuronal remodeling and cardiac hypertrophy induced by chronic pressure overload in guinea pig.

PubMed

Beaumont, Eric; Wright, Gary L; Southerland, Elizabeth M; Li, Ying; Chui, Ray; KenKnight, Bruce H; Armour, J Andrew; Ardell, Jeffrey L

2016-05-15

Our objective was to determine whether chronic vagus nerve stimulation (VNS) mitigates pressure overload (PO)-induced remodeling of the cardioneural interface. Guinea pigs (n = 48) were randomized to right or left cervical vagus (RCV or LCV) implant. After 2 wk, chronic left ventricular PO was induced by partial (15-20%) aortic constriction. Of the 31 animals surviving PO induction, 10 were randomized to RCV VNS, 9 to LCV VNS, and 12 to sham VNS. VNS was delivered at 20 Hz and 1.14 ± 0.03 mA at a 22% duty cycle. VNS commenced 10 days after PO induction and was maintained for 40 days. Time-matched controls (n = 9) were evaluated concurrently. Echocardiograms were obtained before and 50 days after PO. At termination, intracellular current-clamp recordings of intrinsic cardiac (IC) neurons were studied in vitro to determine effects of therapy on soma characteristics. Ventricular cardiomyocyte sizes were assessed with histology along with immunoblot analysis of selected proteins in myocardial tissue extracts. In sham-treated animals, PO increased cardiac output (34%, P < 0.004), as well as systolic (114%, P < 0.04) and diastolic (49%, P < 0.002) left ventricular volumes, a hemodynamic response prevented by VNS. PO-induced enhancements of IC synaptic efficacy and muscarinic sensitivity of IC neurons were mitigated by chronic VNS. Increased myocyte size, which doubled in PO (P < 0.05), was mitigated by RCV. PO hypertrophic myocardium displayed decreased glycogen synthase (GS) protein levels and accumulation of the phosphorylated (inactive) form of GS. These PO-induced changes in GS were moderated by left VNS. Chronic VNS targets IC neurons accompanying PO to obtund associated adverse cardiomyocyte remodeling. Copyright © 2016 the American Physiological Society.

Accurate control of oxygen level in cells during culture on silicone rubber membranes with application to stem cell differentiation.

PubMed

Powers, Daryl E; Millman, Jeffrey R; Bonner-Weir, Susan; Rappel, Michael J; Colton, Clark K

2010-01-01

Oxygen level in mammalian cell culture is often controlled by placing culture vessels in humidified incubators with a defined gas phase partial pressure of oxygen (pO(2gas)). Because the cells are consuming oxygen supplied by diffusion, a difference between pO(2gas) and that experienced by the cells (pO(2cell)) arises, which is maximal when cells are cultured in vessels with little or no oxygen permeability. Here, we demonstrate theoretically that highly oxygen-permeable silicone rubber membranes can be used to control pO(2cell) during culture of cells in monolayers and aggregates much more accurately and can achieve more rapid transient response following a disturbance than on polystyrene and fluorinated ethylene-propylene copolymer membranes. Cell attachment on silicone rubber was achieved by physical adsorption of fibronectin or Matrigel. We use these membranes for the differentiation of mouse embryonic stem cells to cardiomyocytes and compare the results with culture on polystyrene or on silicone rubber on top of polystyrene. The fraction of cells that are cardiomyocyte-like increases with decreasing pO(2) only when using oxygen-permeable silicone membrane-based dishs, which contract on silicone rubber but not polystyrene. The high permeability of silicone rubber results in pO(2cell) being equal to pO(2gas) at the tissue-membrane interface. This, together with geometric information from histological sections, facilitates development of a model from which the pO(2) distribution within the resulting aggregates is computed. Silicone rubber membranes have significant advantages over polystyrene in controlling pO(2cell), and these results suggest they are a valuable tool for investigating pO(2) effects in many applications, such as stem cell differentiation. Copyright 2009 American Institute of Chemical Engineers

Oxygen nonstoichiometry and thermodynamic quantities in solid solution SrFe1-xSnxO3-δ

NASA Astrophysics Data System (ADS)

Merkulov, O. V.; Markov, A. A.; Leonidov, I. A.; Patrakeev, M. V.; Kozhevnikov, V. L.

2018-06-01

The oxygen content (3-δ) variations in tin substituted derivatives SrFe1-xSnxO3-δ, where x = 0.05, 0.1, 0.17 and 0.25, of perovskite-like strontium ferrite, have been studied by coulometric titration measurements within oxygen partial pressure (pO2) range 10-19-10-2 atm at 800-950 °С. The obtained dependencies of (3-δ) from pO2 and temperature are used for calculations of partial molar thermodynamic functions of oxygen in the oxide structure. It is found that a satisfactory explanation of the experimental results can be attained within frameworks of the ideal solution model with ion and electron defects appearing in the result of oxidation and disproportionation of iron cations. The increase of the oxidation reaction enthalpy with tin content is consistent with the increase of the unit cell parameter, i.e., the stretch and relaxation of Fe-O chemical bonds.

Continuous arterial PO2 profiles in unrestrained, undisturbed aquatic turtles during routine behaviors

PubMed Central

Hicks, James W.

2016-01-01

ABSTRACT Mammals and birds maintain high arterial partial pressure of oxygen (PO2) values in order to preserve near-complete hemoglobin (Hb) oxygen (O2) saturation. In diving mammals and birds, arterial O2 follows a primarily monotonic decline and then recovers quickly after dives. In laboratory studies of submerged freshwater turtles, arterial O2 depletion typically follows a similar pattern. However, in these studies, turtles were disturbed, frequently tethered to external equipment and confined either to small tanks or breathing holes. Aquatic turtles can alter cardiac shunting patterns, which will affect arterial PO2 values. Consequently, little is known about arterial O2 regulation and use in undisturbed turtles. We conducted the first study to continuously measure arterial PO2 using implanted microelectrodes and a backpack logger in undisturbed red-eared sliders during routine activities. Arterial PO2 profiles during submergences varied dramatically, with no consistent patterns. Arterial PO2 was also lower than previously reported during all activities, with values rarely above 50 mmHg (85% Hb saturation). There was no difference in mean PO2 between five different activities: submerged resting, swimming, basking, resting at the surface and when a person was present. These results suggest significant cardiac shunting occurs during routine activities as well as submergences. However, the lack of relationship between PO2 and any activity suggests that cardiac shunts are not regulated to maintain high arterial PO2 values. These data support the idea that cardiac shunting is the passive by-product of regulation of vascular resistances by the autonomic nervous system. PMID:27618860

Simple method to make a supersaturated oxygen fluid.

PubMed

Tange, Yoshihiro; Yoshitake, Shigenori; Takesawa, Shingo

2018-01-22

Intravenous oxygenation has demonstrated significant increase in partial pressure of oxygen (PO 2 ) in animal models. A highly dissolved oxygen solution might be able to provide a sufficient level of oxygen delivery to the tissues and organs in patients with hypoxia. However, conventional fluid oxygenation methods have required the use of original devices. If simpler oxygenation of a solution is possible, it will be a useful strategy for application in clinical practice. We simply developed its administration by injection of either air or oxygen gas into conventional saline. We determined the PO 2 values in the solutions in comparison with conventional saline in vitro. To examine the effects of the administration of the new solutions on the blood gas profile, we diluted bovine blood with either conventional or the new solutions and analyzed PO 2 , oxygen saturation (SO 2 ) and total oxygen content. PO 2 levels in the blood and new solution mixture significantly increased with each additional injected gas volume. Significant increases in the PO 2 and SO 2 of the bovine blood were found in those blood samples with the new solution, as compared with those with the control solution. These results suggest that this solution promotes oxygen delivery to the hypoxic tissue and recovery from hypoxia. This method is simpler and easier than previous methods.

High-spatial-resolution mapping of the oxygen concentration in cortical tissue (Conference Presentation)

NASA Astrophysics Data System (ADS)

Jaswal, Rajeshwer S.; Yaseen, Mohammad A.; Fu, Buyin; Boas, David A.; Sakadžic, Sava

2016-03-01

Due to a lack of imaging tools for high-resolution imaging of cortical tissue oxygenation, the detailed maps of the oxygen partial pressure (PO2) around arterioles, venules, and capillaries remain largely unknown. Therefore, we have limited knowledge about the mechanisms that secure sufficient oxygen delivery in microvascular domains during brain activation, and provide some metabolic reserve capacity in diseases that affect either microvascular networks or the regulation of cerebral blood flow (CBF). To address this challenge, we applied a Two-Photon PO2 Microscopy to map PO2 at different depths in mice cortices. Measurements were performed through the cranial window in the anesthetized healthy mice as well as in the mouse models of microvascular dysfunctions. In addition, microvascular morphology was recorded by the two-photon microscopy at the end of each experiment and subsequently segmented. Co-registration of the PO2 measurements and exact microvascular morphology enabled quantification of the tissue PO2 dependence on distance from the arterioles, capillaries, and venules at various depths. Our measurements reveal significant spatial heterogeneity of the cortical tissue PO2 distribution that is dominated by the high oxygenation in periarteriolar spaces. In cases of impaired oxygen delivery due to microvascular dysfunction, significant reduction in tissue oxygenation away from the arterioles was observed. These tissue domains may be the initial sites of cortical injury that can further exacerbate the progression of the disease.

Study of Chromium Oxide Activities in EAF Slags

NASA Astrophysics Data System (ADS)

Yan, Baijun; Li, Fan; Wang, Hui; Sichen, Du

2016-02-01

The activity coefficients of chromium in Cu-Cr melts were determined by equilibrating liquid copper with solid Cr2O3 in CO-CO2 atmosphere. The temperature dependence of the activity coefficients of chromium in Cu-Cr melts could be expressed as lg γ_{Cr}(s)^{0} = { 3 2 5 9( ± 1 8 6} )/T - 0. 5 9( { ± 0. 1} ). Based on the above results, the activities of bivalent and trivalent chromium oxide in some slags at 1873 K (1600 °C) were measured. The slags were equilibrated with Cu-Cr melts under two oxygen partial pressures ( {p_{O}_{ 2} }} } = 6.9 × 10-4 and 1.8 × 10-6 Pa, respectively). The morphology of the quenched slags and the solubility of chromium oxide in the melts were investigated by EPMA, SEM, and XRD. Under both oxygen partial pressures, the slags were saturated by the solid solution MgAl2- x Cr x O4- δ . At the low oxygen partial pressure (1.8 × 10-6 Pa), the content of Cr in the liquid phase varied from 0.4 to 1.6 mass pct with the total Cr content in the slags increasing from 1.3 to 10.8 mass pct. At the high oxygen partial pressure (6.9 × 10-4 Pa), the content of Cr in the liquid phase decreased to the level of 0.2 to 0.6 mass pct. Both the activities of CrO and Cr2O3 in slag were found to increase approximately linearly with the increase of the total Cr content in slag. While the oxygen partial pressure had minor effect on the activity of Cr2O3 in the slag, it had significant effect on the activity of CrO.

Physiological oxygen concentration alters glioma cell malignancy and responsiveness to photodynamic therapy in vitro.

PubMed

Albert, Ina; Hefti, Martin; Luginbuehl, Vera

2014-11-01

The partial pressure of oxygen (pO2) in brain tumors ranges from 5 to 15%. Nevertheless, the majority of in vitro experiments with glioblastoma multiforme (GBM) cell lines are carried out under an atmospheric pO2 of 19 to 21%. Recently, 5-aminolevulinic acid (5-ALA), a precursor of protoporphyrin IX (PpIX), has been introduced to neurosurgery to allow for photodynamic diagnosis and photodynamic therapy (PDT) in high-grade gliomas. Here, we investigate whether low pO2 affects GBM cell physiology, PpIX accumulation, or PDT efficacy. GBM cell lines (U-87 MG and U-251 MG) were cultured under atmospheric (pO2  =  19%) and physiological (pO2  =  9%) oxygen concentrations. PpIX accumulation and localization were investigated, and cell survival and cell death were observed following in vitro PDT. A physiological pO2 of 9% stimulated GBM cell migration, increased hypoxia-inducible factor (HIF)-1 alpha levels, and elevated resistance to camptothecin in U-87 MG cells compared to cultivation at a pO2 of 19%. This oxygen reduction did not alter 5-ALA-induced intracellular PpIX accumulation. However, physiological pO2 changed the responsiveness of U-87 MG but not of U-251 MG cells to in vitro PDT. Around 20% more irradiation light was required to kill U-87 MG cells at physiological pO2, resulting in reduced lactate dehydrogenase (LDH) release (one- to two-fold) and inhibition of caspase 3 activation. Reduction of oxygen concentration from atmospheric to a more physiological level can influence the malignant behavior and survival of GBM cell lines after in vitro PDT. Therefore, precise oxygen concentration control should be considered when designing and performing experiments with GBM cells.

The diving bell and the spider: the physical gill of Argyroneta aquatica.

PubMed

Seymour, Roger S; Hetz, Stefan K

2011-07-01

Argyroneta aquatica is a unique air-breathing spider that lives virtually its entire life under freshwater. It creates a dome-shaped web between aquatic plants and fills the diving bell with air carried from the surface. The bell can take up dissolved O(2) from the water, acting as a 'physical gill'. By measuring bell volume and O(2) partial pressure (P(O(2))) with tiny O(2)-sensitive optodes, this study showed that the spiders produce physical gills capable of satisfying at least their resting requirements for O(2) under the most extreme conditions of warm stagnant water. Larger spiders produced larger bells of higher O(2) conductance (G(O(2))). G(O(2)) depended on surface area only; effective boundary layer thickness was constant. Bells, with and without spiders, were used as respirometers by measuring G(O(2)) and the rate of change in P(O(2)). Metabolic rates were also measured with flow-through respirometry. The water-air P(O(2)) difference was generally less than 10 kPa, and spiders voluntarily tolerated low internal P(O(2)) approximately 1-4 kPa before renewal with air from the surface. The low P(O(2)) in the bell enhanced N(2) loss from the bell, but spiders could remain inside for more than a day without renewal. Spiders appeared to enlarge the bells in response to higher O(2) demands and lower aquatic P(O(2)).

Why is the partial oxygen pressure of human tissues a crucial parameter? Small molecules and hypoxia

PubMed Central

Carreau, Aude; Hafny-Rahbi, Bouchra El; Matejuk, Agata; Grillon, Catherine; Kieda, Claudine

2011-01-01

Abstract Oxygen supply and diffusion into tissues are necessary for survival. The oxygen partial pressure (pO2), which is a key component of the physiological state of an organ, results from the balance between oxygen delivery and its consumption. In mammals, oxygen is transported by red blood cells circulating in a well-organized vasculature. Oxygen delivery is dependent on the metabolic requirements and functional status of each organ. Consequently, in a physiological condition, organ and tissue are characterized by their own unique ‘tissue normoxia’ or ‘physioxia’ status. Tissue oxygenation is severely disturbed during pathological conditions such as cancer, diabetes, coronary heart disease, stroke, etc., which are associated with decrease in pO2, i.e. ‘hypoxia’. In this review, we present an array of methods currently used for assessing tissue oxygenation. We show that hypoxia is marked during tumour development and has strong consequences for oxygenation and its influence upon chemotherapy efficiency. Then we compare this to physiological pO2 values of human organs. Finally we evaluate consequences of physioxia on cell activity and its molecular modulations. More importantly we emphasize the discrepancy between in vivo and in vitro tissue and cells oxygen status which can have detrimental effects on experimental outcome. It appears that the values corresponding to the physioxia are ranging between 11% and 1% O2 whereas current in vitro experimentations are usually performed in 19.95% O2, an artificial context as far as oxygen balance is concerned. It is important to realize that most of the experiments performed in so-called normoxia might be dangerously misleading. PMID:21251211

Why is the partial oxygen pressure of human tissues a crucial parameter? Small molecules and hypoxia.

PubMed

Carreau, Aude; El Hafny-Rahbi, Bouchra; Matejuk, Agata; Grillon, Catherine; Kieda, Claudine

2011-06-01

Oxygen supply and diffusion into tissues are necessary for survival. The oxygen partial pressure (pO(2)), which is a key component of the physiological state of an organ, results from the balance between oxygen delivery and its consumption. In mammals, oxygen is transported by red blood cells circulating in a well-organized vasculature. Oxygen delivery is dependent on the metabolic requirements and functional status of each organ. Consequently, in a physiological condition, organ and tissue are characterized by their own unique 'tissue normoxia' or 'physioxia' status. Tissue oxygenation is severely disturbed during pathological conditions such as cancer, diabetes, coronary heart disease, stroke, etc., which are associated with decrease in pO(2), i.e. 'hypoxia'. In this review, we present an array of methods currently used for assessing tissue oxygenation. We show that hypoxia is marked during tumour development and has strong consequences for oxygenation and its influence upon chemotherapy efficiency. Then we compare this to physiological pO(2) values of human organs. Finally we evaluate consequences of physioxia on cell activity and its molecular modulations. More importantly we emphasize the discrepancy between in vivo and in vitro tissue and cells oxygen status which can have detrimental effects on experimental outcome. It appears that the values corresponding to the physioxia are ranging between 11% and 1% O(2) whereas current in vitro experimentations are usually performed in 19.95% O(2), an artificial context as far as oxygen balance is concerned. It is important to realize that most of the experiments performed in so-called normoxia might be dangerously misleading. © 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

Effects of background oxygen pressure on dielectric and ferroelectric properties of epitaxial (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.10,Sb0.06)O3 thin films on SrTiO3

NASA Astrophysics Data System (ADS)

Abazari, M.; Akdoǧan, E. K.; Safari, A.

2008-11-01

Oxygen partial pressure (PO_2) in pulsed laser deposition significantly influences the composition, microstructure, and electrical properties of epitaxial misfit strain-relieved 450nm ⟨001⟩ oriented epitaxial (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.10,Sb0.06)O3 thin films on SrRuO3 coated SrTiO3. Films deposited at 400mTorr exhibit high remnant and saturated polarization of 7.5 and 16.5μC /cm2, respectively, which is ˜100% increase over the ones grown at 100mTorr. The dielectric constant linearly increases from 220 to 450 with increasing PO2. The observed changes in surface morphology of the films and their properties are shown to be due to the suppression of volatile A-site cation loss.

FirefOx Design Reference fO2 Sensor for Hot, Deep Atmospheres

NASA Astrophysics Data System (ADS)

Izenberg, N.; Papadakis, S.; Deglau, D.; Francomacaro, A. S.

2016-12-01

Understanding the composition of the lowest portion of Venus' atmosphere is critical to knowing the stable mineralogy of the rocks there. Oxygen gas is a critical trace component, with fugacity, or partial pressure, estimated in the range of 10-19 to 10-22 from early probe measurements down to 22km altitude (Pioneer Venus, Venera), chemical equilibrium measurements, and other modeling. "FirefOx" is a simple oxygen fugacity sensor with the express purpose of determining the partial pressure of oxygen in the lowest scale heights of the Venus atmosphere, and especially the lowest hundreds of meters; the surface atmosphere interface, where the atmosphere and surface move to thermodynamic equilibrium. Knowledge of the fO2 at the surface atmosphere interface is crucial to determining the stable mineralogy of surface materials (e.g. magnetite vs. hematite) and gas chemistry in the near-surface atmosphere FirefOx is a Metal/Metal Oxide oxygen fugacity sensor intended to be mounted on the outside of a Venus descent probe, with electronics housed inside a thermally controlled environment. The sole sensor capability is the precise, accurate detection of the partial pressure of oxygen gas (fO2) in the near-surface environment of Venus, at up to 95-bar pressure (predominantly CO2. Surface temperatures at mean planetary elevation are near 735 K, thus a required operational temperature range of 710-740 K covers a range of near-surface elevations. FirefOx system requirements are low ( 100-200 grams, mass, milliwatt power, several kilobytes total science data). A design reference sensor, composed of custom, Yittria-ZrO ceramic electrolyte, with an encapsulated Pd/PdO standard and patterned Pt electrodes has demonstrated scientifically useful signal-to-noise millivolt level potential at temperatures as low as 620 K, relatable to fO2 by a Nernst equation E = RT/4F ln(PO2/PrefO2) where E = open circuit potential across the sensor electrolyte, R = universal gas constant, T = temperature, F = Faraday constant, PrefO2 = reference oxygen pressure, and PO2 = unknown oxygen pressure of the outside environment. The FirefOx sensor shows promise for direct fO2 measurement on potential upcoming Venus in situ and other deep atmosphere probes.

The mechanism of improved aeration due to gas films on leaves of submerged rice.

PubMed

Verboven, Pieter; Pedersen, Ole; Ho, Quang Tri; Nicolai, Bart M; Colmer, Timothy D

2014-10-01

Some terrestrial wetland plants, such as rice, have super-hydrophobic leaf surfaces which retain a gas film when submerged. O2 movement through the diffusive boundary layer (DBL) of floodwater, gas film and stomata into leaf mesophyll was explored by means of a reaction-diffusion model that was solved in a three-dimensional leaf anatomy model. The anatomy and dark respiration of leaves of rice (Oryza sativa L.) were measured and used to compute O2 fluxes and partial pressure of O2 (pO2 ) in the DBL, gas film and leaf when submerged. The effects of floodwater pO2 , DBL thickness, cuticle permeability, presence of gas film and stomatal opening were explored. Under O2 -limiting conditions of the bulk water (pO2  < 10 kPa), the gas film significantly increases the O2 flux into submerged leaves regardless of whether stomata are fully or partly open. With a gas film, tissue pO2 substantially increases, even for the slightest stomatal opening, but not when stomata are completely closed. The effect of gas films increases with decreasing cuticle permeability. O2 flux and tissue pO2 decrease with increasing DBL thickness. The present modelling analysis provides a mechanistic understanding of how leaf gas films facilitate O2 entry into submerged plants. © 2014 John Wiley & Sons Ltd.

Evidence for minimal oxygen heterogeneity in the healthy human pulmonary acinus

PubMed Central

Tawhai, Merryn H.

2011-01-01

It has been suggested that the human pulmonary acinus operates at submaximal efficiency at rest due to substantial spatial heterogeneity in the oxygen partial pressure (Po2) in alveolar air within the acinus. Indirect measurements of alveolar air Po2 could theoretically mask significant heterogeneity if intra-acinar perfusion is well matched to Po2. To investigate the extent of intra-acinar heterogeneity, we developed a computational model with anatomically based structure and biophysically based equations for gas exchange. This model yields a quantitative prediction of the intra-acinar O2 distribution that cannot be measured directly. Temporal and spatial variations in Po2 in the intra-acinar air and blood are predicted with the model. The model, representative of a single average acinus, has an asymmetric multibranching respiratory airways geometry coupled to a symmetric branching conducting airways geometry. Advective and diffusive O2 transport through the airways and gas exchange into the capillary blood are incorporated. The gas exchange component of the model includes diffusion across the alveolar air-blood membrane and O2-hemoglobin binding. Contrary to previous modeling studies, simulations show that the acinus functions extremely effectively at rest, with only a small degree of intra-acinar Po2 heterogeneity. All regions of the model acinus, including the peripheral generations, maintain a Po2 >100 mmHg. Heterogeneity increases slightly when the acinus is stressed by exercise. However, even during exercise the acinus retains a reasonably homogeneous gas phase. PMID:21071589

A LED-based phosphorimeter for measurement of microcirculatory oxygen pressure.

PubMed

Guerci, Philippe; Ince, Yasin; Heeman, Paul; Faber, Dirk; Ergin, Bulent; Ince, Can

2017-02-01

Quantitative measurements of microcirculatory and tissue oxygenation are of prime importance in experimental research. The noninvasive phosphorescence quenching method has given further insight into the fundamental mechanisms of oxygen transport to healthy tissues and in models of disease. Phosphorimeters are devices dedicated to the study of phosphorescence quenching. The experimental applications of phosphorimeters range from measuring a specific oxygen partial pressure (Po 2 ) in cellular organelles such as mitochondria, finding values of Po 2 distributed over an organ or capillaries, to measuring microcirculatory Po 2 changes simultaneously in several organ systems. Most of the current phosphorimeters use flash lamps as a light excitation source. However, a major drawback of flash lamps is their inherent plasma glow that persists for tens of microseconds after the primary discharge. This complex distributed excitation pattern generated by the flash lamp can lead to inaccurate Po 2 readings unless a deconvolution analysis is performed. Using light-emitting diode (LED), a rectangular shaped light pulse can be generated that provides a more uniformly distributed excitation signal. This study presents the design and calibration process of an LED-based phosphorimeter (LED-P). The in vitro calibration of the LED-P using palladium(II)-meso-tetra(4-carboxyphenyl)-porphyrin (Pd-TCCP) as a phosphorescent dye is presented. The pH and temperature were altered to assess whether the decay times of the Pd-TCCP measured by the LED-P were significantly influenced. An in vivo validation experiment was undertaken to measure renal cortical Po 2 in a rat subjected to hypoxic ventilation conditions and ischemia/reperfusion. The benefits of using LEDs as a light excitation source are presented. Copyright © 2017 the American Physiological Society.

Biotic and abiotic factors affect the nest environment of embryonic leatherback turtles, Dermochelys coriacea.

PubMed

Wallace, Bryan P; Sotherland, Paul R; Spotila, James R; Reina, Richard D; Franks, Bryan F; Paladino, Frank V

2004-01-01

Clutches of leatherback turtles, Dermochelys coriacea, have lower hatching success than those of other sea turtles, but causes of high embryonic mortality are unknown. We measured characteristics of clutches along with spatial and temporal changes in PO(2) and temperature during incubation to determine the extent to which they affected the developmental environment of leatherback embryos. Minimum PO(2) in nests decreased as both the total number and mass of metabolizing embryos increased. Increases in both the number and mass of metabolizing embryos caused an increase in maximum nest temperature. However, neither PO(2) nor temperature was correlated with hatching success. Our measurements of relatively high nest PO(2) (lowest 17.1 kPa or 16.9% O(2)) indicate that hypoxia apparently does not cause the low hatching success of leatherback clutches. Oxygen partial pressure increased and temperature decreased from the center toward the periphery of leatherback nests. We inferred from these measurements that positions of eggs within nests vary in quality and potentially affect overall developmental success of entire clutches. The large metabolic mass of leatherback clutches and limits to gas flux imposed by the sand create a situation in which leatherback embryos collectively affect their own environment.

A novel, non-invasive diagnostic clinical procedure for the determination of an oxygenation status of chronic lower leg ulcers using peri-ulceral transcutaneous oxygen partial pressure measurements: results of its application in chronic venous insufficiency (CVI).

PubMed

Barnikol, Wolfgang K R; Pötzschke, Harald

2012-01-01

The basis for the new procedure is the simultaneous transcutaneous measurement of the peri-ulceral oxygen partial pressure (tcPO(2)), using a minimum of 4 electrodes which are placed as close to the wound margin as possible, additionally, as a challenge the patient inhales pure oxygen for approximately 15 minutes. In order to evaluate the measurement data and to characterise the wounds, two new oxygen parameters were defined: (1) the oxygen characteristic (K-PO(2)), and (2) the oxygen inhomogeneity (I-PO(2)) of a chronic wound. The first of these is the arithmetic mean of the two lowest tcPO(2) measurement values, and the second is the variation coefficient of the four measurement values. Using the K-PO(2) parameter, a grading of wound hypoxia can be obtained. To begin with, the physiologically regulated (and still compensated) hypoxia with K-PO(2) values of between 35 and 40 mmHg is distinguished from the pathological decompensated hypoxia with K-PO(2) values of between 0 and 35 mmHg; the first of these still stimulates self-healing (within the limits of the oxygen balance). The decompensated hypoxia can be (arbitrarily) divided into "simple" hypoxia (Grade I), intense hypoxia (Grade II) and extreme hypoxia (Grade III), with the possibility of intermediate grades (I/II and II/III).Measurements were carried out using the new procedure on the skin of the right inner ankle of 21 healthy volunteers of various ages, and in 17 CVI (chronic venous insufficiency) wounds. Sixteen of the 17 CVI wounds (i.e., 94%) were found to be pathologically hypoxic, a state which was not found in any of the healthy volunteers. The oxygen inhomogeneity (I-PO(2)) of the individual chronic wounds increased exponentially as a function of the hypoxia grading (K-PO(2)), with a 10-fold increase with extreme hypoxia in contrast to a constant value of approximately 14% in the healthy volunteers. This pronounced oxygen inhomogeneity explains inhomogeneous wound healing, resulting in the so-called mosaic wounds. The hypoxia grades found in all of the chronic wounds was seen to be evenly distributed with values ranging from 0 to 40 mmHg, and therefore extremely inhomogeneous. In terms of oxygenation, chronic wounds are therefore inhomogeneous in two respects: (1) within the wound itself (intra-individual wound inhomogeneity) and (2) between different wounds (inter-individual wound inhomogeneity). Due to the extreme oxygen inhomogeneity, single measurements are not diagnostically useful. In healthy individuals the oxygen inhalation challenge (see above) results in synchronised tcPO(2) oscillations occurring at minute rhythms, which are not seen in CVI wounds. These oscillations can be interpreted as a sign of a functioning arterial vasomotor system.The new procedure is suitable for the routine characterisation of chronic wounds in terms of their oxygen status, and correspondingly, their metabolically determining (and limiting) potential for healing and regeneration. The oxygen characteristic K-PO(2) can furthermore be used as a warning of impending ulceration, since the oxygen provision worsens over time prior to the demise of the ulcerated tissue, thus making a controlled prophylaxis possible.

A novel, non-invasive diagnostic clinical procedure for the determination of an oxygenation status of chronic lower leg ulcers using peri-ulceral transcutaneous oxygen partial pressure measurements: Results of its application in chronic venous insufficiency (CVI)

PubMed Central

Barnikol, Wolfgang K. R.; Pötzschke, Harald

2012-01-01

The basis for the new procedure is the simultaneous transcutaneous measurement of the peri-ulceral oxygen partial pressure (tcPO2), using a minimum of 4 electrodes which are placed as close to the wound margin as possible, additionally, as a challenge the patient inhales pure oxygen for approximately 15 minutes. In order to evaluate the measurement data and to characterise the wounds, two new oxygen parameters were defined: (1) the oxygen characteristic (K-PO2), and (2) the oxygen inhomogeneity (I-PO2) of a chronic wound. The first of these is the arithmetic mean of the two lowest tcPO2 measurement values, and the second is the variation coefficient of the four measurement values. Using the K-PO2 parameter, a grading of wound hypoxia can be obtained. To begin with, the physiologically regulated (and still compensated) hypoxia with K-PO2 values of between 35 and 40 mmHg is distinguished from the pathological decompensated hypoxia with K-PO2 values of between 0 and 35 mmHg; the first of these still stimulates self-healing (within the limits of the oxygen balance). The decompensated hypoxia can be (arbitrarily) divided into “simple” hypoxia (Grade I), intense hypoxia (Grade II) and extreme hypoxia (Grade III), with the possibility of intermediate grades (I/II and II/III). Measurements were carried out using the new procedure on the skin of the right inner ankle of 21 healthy volunteers of various ages, and in 17 CVI (chronic venous insufficiency) wounds. Sixteen of the 17 CVI wounds (i.e., 94%) were found to be pathologically hypoxic, a state which was not found in any of the healthy volunteers. The oxygen inhomogeneity (I-PO2) of the individual chronic wounds increased exponentially as a function of the hypoxia grading (K-PO2), with a 10-fold increase with extreme hypoxia in contrast to a constant value of approximately 14% in the healthy volunteers. This pronounced oxygen inhomogeneity explains inhomogeneous wound healings, resulting in the so-called mosaic wounds. The hypoxia grades found in all of the chronic wounds was seen to be evenly distributed with values ranging from 0 to 40 mmHg, and therefore extremely inhomogeneous. In terms of oxygenation, chronic wounds are therefore inhomogeneous in two respects: (1) within the wound itself (intra-individual wound inhomogeneity) and (2) between different wounds (inter-individual wound inhomogeneity). Due to the extreme oxygen inhomogeneity, single measurements are not diagnostically useful. In healthy individuals the oxygen inhalation challenge (see above) results in synchronised tcPO2 oscillations occurring at minute rhythms, which are not seen in CVI wounds. These oscillations can be interpreted as a sign of a functioning arterial vasomotor system. The new procedure is suitable for the routine characterisation of chronic wounds in terms of their oxygen status, and correspondingly, their metabolically determining (and limiting) potential for healing and regeneration. The oxygen characteristic K-PO2 can furthermore be used as a warning of impending ulceration, since the oxygen provision worsens over time prior to the demise of the ulcerated tissue, thus making a controlled prophylaxis possible. PMID:22737104

Two-photon microscopy measurement of CMRO2 using periarteriolar PO2 gradients(Conference Presentation)

NASA Astrophysics Data System (ADS)

Sakadžić, Sava; Yaseen, Mohammad A.; Jaswal, Rajeshwer S.; Roussakis, Emmanuel; Dale, Anders M.; Buxton, Richard B.; Vinogradov, Sergei A.; Boas, David A.; Devor, Anna

2017-02-01

The cerebral metabolic rate of oxygen (CMRO2) is an essential parameter for evaluating brain function and pathophysiology. Measurements of CMRO2 with high spatio-temporal resolution are critically important for understanding how the brain copes with metabolic and blood perfusion changes associated with various clinical conditions, such as stroke, periinfarct depolarizations, and various microvasculopathies (e.g., Alzheimer's disease, chronic hypertension). CMRO2 measurements are also important for understanding the physiological underpinnings of functional Magnetic Resonance Imaging signals. However, the currently available approaches for quantifying CMRO2 rely on complex multimodal imaging and mathematical modeling. Here, we introduce a novel method that allows estimation of CMRO2 based on a single measurement modality - two-photon phosphorescence lifetime microscopy (2PLM) imaging of the partial pressure of oxygen (PO2) in cortical tissue. CMRO2 is estimated by fitting the changes of tissue PO2 around cortical penetrating arterioles with the Krogh cylinder model of oxygen diffusion. We measured the baseline CMRO2 in anesthetized rats, and modulated tissue PO2 levels by manipulating the depth of anesthesia. This method has a spatial resolution of approximately 200 μm and it may provide CMRO2 measurements in individual cortical layers or within confined cortical regions such as in ischemic penumbra and the foci of functional activation.

Reduced Adipose Tissue Oxygenation in Human Obesity

PubMed Central

Pasarica, Magdalena; Sereda, Olga R.; Redman, Leanne M.; Albarado, Diana C.; Hymel, David T.; Roan, Laura E.; Rood, Jennifer C.; Burk, David H.; Smith, Steven R.

2009-01-01

OBJECTIVE— Based on rodent studies, we examined the hypothesis that increased adipose tissue (AT) mass in obesity without an adequate support of vascularization might lead to hypoxia, macrophage infiltration, and inflammation. RESEARCH DESIGN AND METHODS— Oxygen partial pressure (AT pO2) and AT temperature in abdominal AT (9 lean and 12 overweight/obese men and women) was measured by direct insertion of a polarographic Clark electrode. Body composition was measured by dual-energy X-ray absorptiometry, and insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp. Abdominal subcutaneous tissue was used for staining, quantitative RT-PCR, and chemokine secretion assay. RESULTS— AT pO2 was lower in overweight/obese subjects than lean subjects (47 ± 10.6 vs. 55 ± 9.1 mmHg); however, this level of pO2 did not activate the classic hypoxia targets (pyruvate dehydrogenase kinase and vascular endothelial growth factor [VEGF]). AT pO2 was negatively correlated with percent body fat (R = −0.50, P < 0.05). Compared with lean subjects, overweight/obese subjects had 44% lower capillary density and 58% lower VEGF, suggesting AT rarefaction (capillary drop out). This might be due to lower peroxisome proliferator–activated receptor γ1 and higher collagen VI mRNA expression, which correlated with AT pO2 (P < 0.05). Of clinical importance, AT pO2 negatively correlated with CD68 mRNA and macrophage inflammatory protein 1α secretion (R = −0.58, R = −0.79, P < 0.05), suggesting that lower AT pO2 could drive AT inflammation in obesity. CONCLUSIONS— Adipose tissue rarefaction might lie upstream of both low AT pO2 and inflammation in obesity. These results suggest novel approaches to treat the dysfunctional AT found in obesity. PMID:19074987

Modulation of tumor hypoxia by topical formulations with vasodilators for enhancing therapy.

PubMed

Abramovic, Zrinka; Hou, Huagang; Julijana, Kristl; Sentjurc, Marjeta; Lariviere, Jean P; Swartz, Harold M; Khan, Nadeem

2011-01-01

Tumor hypoxia is a well known therapeutic problem which contributes to radioresistance and aggressive tumor characteristics. Lack of techniques for repeated measurements of tumor oxygenation (pO(2), partial pressure of oxygen) has restricted the optimization of hypoxia modifying methods and their efficacious application with radiotherapy. We have investigated a non-invasive method to enhance tissue pO(2) of peripheral tumors using topical application of formulations with BN (Benzyl Nicotinate), a vasodilator, and have used EPR (Electron Paramagnetic Resonance) oximetry to follow its effect on tumor oxygenation.We incorporated 2.5% BN in both hydrogel and microemulsions and investigated the effects on pO(2) of subcutaneous RIF-1 (Radiation Induced Fibrosarcoma) tumors in C3H mice. The experiments were repeated for five consecutive days. The topical application of BN in hydrogel led to a significant increase from a pre-treatment pO(2) of 9.3 mmHg to 11 - 16 mmHg at 30 - 50 min on day 1. However, the magnitude and the time of significant increase in pO(2) decreased with repeated topical applications. The BN in a microemulsion resulted in a significant increase from a baseline pO(2) of 8.8 mmHg to 13 - 18 mmHg at 10 - 50 min on day 1. Experiments repeated on subsequent days showed a decline in the magnitude of pO(2) increase on repeated applications. No significant change in tumor pO(2) was observed in experiments with formulations without BN (vehicle only).EPR oximetry was successfully used to follow the temporal changes in tumor pO(2) during repeated applications for five consecutive days. This approach can be potentially used to enhance radiotherapeutic outcome by scheduling radiation doses when an increase in tumor pO(2) is observed after topical applications of BN formulations.

MODULATION OF TUMOR HYPOXIA BY TOPICAL FORMULATIONS WITH VASODILATORS FOR ENHANCING THERAPY

PubMed Central

Abramovic, Zrinka; Hou, Huagang; Julijana, Kristl; Sentjurc, Marjeta; Lariviere, Jean P; Swartz, Harold M; Khan, Nadeem

2011-01-01

Tumor hypoxia is a well known therapeutic problem which contributes to radioresistance and aggressive tumor characteristics. Lack of techniques for repeated measurements of tumor oxygen (pO2, partial pressure of oxygen) has restricted the optimization of hypoxia modifying methods and their efficacious application with radiotherapy. We have investigated a non-invasive method to enhance tissue pO2 of peripheral tumors using topical application of formulations with BN (Benzyl Nicotinate), a vasodilator, and have used EPR (Electron Paramagnetic Resonance) oximetry to follow its effect on tumor oxygenation. We incorporated 2.5% BN in both hydrogel and microemulsions and investigated the effects on pO2 of subcutaneous RIF-1 (Radiation Induced Fibrosarcoma) tumors in C3H mice. The experiments were repeated for five consecutive days. The topical application of BN in hydrogel led to a significant increase from a pre-treatment pO2 of 9.3 mmHg to 11 - 16 mmHg at 30 - 50 min on day 1. However, the magnitude and the time of significant increase in pO2 decreased with repeated topical applications. The BN in a microemulsion resulted in a significant increase from a baseline pO2 of 8.8 mmHg to 13 - 18 mmHg at 10 - 50 min on day 1. Experiments repeated on subsequent days showed a decline in the magnitude of pO2 increase on repeated applications. No significant change in tumor pO2 was observed in experiments with formulations without BN (vehicle only). EPR oximetry was successfully used to follow the temporal changes in tumor pO2 during repeated applications for five consecutive days. This approach could be potentially used to enhance radiotherapeutic outcome by scheduling radiation doses when an increase in tumor pO2 is observed after topical applications of BN formulations. PMID:21445772

The effect of nimodipine on cerebral oxygenation in patients with poor-grade subarachnoid hemorrhage.

PubMed

Stiefel, Michael F; Heuer, Gregory G; Abrahams, John M; Bloom, Stephanie; Smith, Michelle J; Maloney-Wilensky, Eileen; Grady, M Sean; LeRoux, Peter D

2004-10-01

Nimodipine has been shown to improve neurological outcome after subarachnoid hemorrhage (SAH); the mechanism of this improvement, however, is uncertain. In addition, adverse systemic effects such as hypotension have been described. The authors investigated the effect of nimodipine on brain tissue PO2. Patients in whom Hunt and Hess Grade IV or V SAH had occurred who underwent aneurysm occlusion and had stable blood pressure were prospectively evaluated using continuous brain tissue PO2 monitoring. Nimodipine (60 mg) was delivered through a nasogastric or Dobhoff tube every 4 hours. Data were obtained from 11 patients and measurements of brain tissue PO2, intracranial pressure (ICP), mean arterial blood pressure (MABP), and cerebral perfusion pressure (CPP) were recorded every 15 minutes. Nimodipine resulted in a significant reduction in brain tissue PO2 in seven (64%) of 11 patients. The baseline PO2 before nimodipine administration was 38.4+/-10.9 mm Hg. The baseline MABP and CPP were 90+/-20 and 84+/-19 mm Hg, respectively. The greatest reduction in brain tissue PO2 occurred 15 minutes after administration, when the mean pressure was 26.9+/-7.7 mm Hg (p < 0.05). The PO2 remained suppressed at 30 minutes (27.5+/-7.7 mm Hg [p < 0.05]) and at 60 minutes (29.7+/-11.1 mm Hg [p < 0.05]) after nimodipine administration but returned to baseline levels 2 hours later. In the seven patients in whom brain tissue PO2 decreased, other physiological variables such as arterial saturation, end-tidal CO2, heart rate, MABP, ICP, and CPP did not demonstrate any association with the nimodipine-induced reduction in PO2. In four patients PO2 remained stable and none of these patients had a significant increase in brain tissue PO2. Although nimodipine use is associated with improved outcome following SAH, in some patients it can temporarily reduce brain tissue PO2.

Carrier Compensation Induced by Thermal Annealing in Al-Doped ZnO Films

PubMed Central

Koida, Takashi; Kaneko, Tetsuya; Shibata, Hajime

2017-01-01

This study investigated carrier compensation induced by thermal annealing in sputtered ZnO:Al (Al2O3: 0.25, 0.5, 1.0, and 2.0 wt %) films. The films were post-annealed in a N2 atmosphere at low (1 × 10−23 atm) and high (1 × 10−4 atm) oxygen partial pressures (PO2). In ZnO:Al films with low Al contents (i.e., 0.25 wt %), the carrier density (n) began to decrease at annealing temperatures (Ta) of 600 °C at low PO2. At higher PO2 and/or Al contents, n values began to decrease significantly at lower Ta (ca. 400 °C). In addition, Zn became desorbed from the films during heating in a high vacuum (i.e., <1 × 10−7 Pa). These results suggest the following: (i) Zn interstitials and Zn vacancies are created in the ZnO lattice during post-annealing treatments, thereby leading to carrier compensation by acceptor-type Zn vacancies; (ii) The compensation behavior is significantly enhanced for ZnO:Al films with high Al contents. PMID:28772501

Influence of oxygen partial pressure on the characteristics of human hepatocarcinoma cells.

PubMed

Trepiana, Jenifer; Meijide, Susana; Navarro, Rosaura; Hernández, M Luisa; Ruiz-Sanz, José Ignacio; Ruiz-Larrea, M Begoña

2017-08-01

Most of the in vitro studies using liver cell lines have been performed under atmospheric oxygen partial pressure (21% O 2 ). However, the oxygen concentrations in the liver and cancer cells are far from this value. In the present study, we have evaluated the influence of oxygen on 1) the tumor cell lines features (growth, steady-state ROS levels, GSH content, activities of antioxidant enzymes, p66 Shc and SOD expressions, metalloproteinases secretion, migration, invasion, and adhesion) of human hepatocellular carcinoma cell lines, and b) the response of the cells to an oxidant stimulus (aqueous leaf extract of the V. baccifera plant species). For this purpose, three hepatocarcinoma cell lines with different p53 status, HepG2 (wild-type), Huh7 (mutated), and Hep3B (deleted), were cultured (6-30 days) under atmospheric (21%) and more physiological (8%) pO 2 . Results showed that after long-term culturing at 8% versus 21% O 2 , the cellular proliferation rate and the steady-state levels of mitochondrial O 2 - were unaffected. However, the intracellular basal ROS levels were higher independently of the characteristics of the cell line. Moreover, the lower pO 2 was associated with lower glutathione content, the induction of p66 Shc and Mn-SOD proteins, and increased SOD activity only in HepG2. This cell line also showed a higher migration rate, secretion of active metalloproteinases, and a faster invasion. HepG2 cells were more resistant to the oxidative stress induced by V. baccifera. Results suggest that the long-term culturing of human hepatoma cells at a low, more physiological pO 2 induces antioxidant adaptations that could be mediated by p53, and may alter the cellular response to a subsequent oxidant challenge. Data support the necessity of validating outcomes from studies performed with hepatoma cell cultures under ambient O 2 . Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Change of oxygen pressure in glioblastoma tissue under various conditions.

PubMed

Beppu, Takaaki; Kamada, Katsura; Yoshida, Yuki; Arai, Hiroshi; Ogasawara, Kuniaki; Ogawa, Akira

2002-05-01

Measurement of oxygen pressure (pO2) in tumor tissue is important, because pO2 is a major factor for radiosensitivity in malignant glioma treatment. We attempted to elucidate the changes in pO2 level in glioblastoma tissue of patients under various conditions. Eighteen patients with newly diagnosed glioblastoma were recruited to this study. Disposable Clark-type electrodes were inserted using CT guided stereotactic surgery under local anesthesia and left in the intra- and peritumoral regions. pO2 was measured in patients under conditions of being awake and asleep, inhaling 100% O2, being administered osmotic diuretics and following hyperbaric oxygen exposure (HBO). Peritumoral tissue had a significantly higher pO2 value in both awake and sleeping patients. O2 inhalation could not significantly increase the pO2 level, whereas administration of osmotic diuretics induced an increase in pO2 levels in peritumoral tissue alone. The pO2 levels were significantly increased in both regions after HBO, and a high pO2 level was maintained until 15 min after HBO in both regions. It is possible that the pO2 level in peritumoral tissue is affected by intracranial pressure, whereas that in the intratumoral tissue is usually low. HBO was the optimal procedure for oxygenation, but its benefit was reduced over time.

Validation of the i-STAT system for the analysis of blood gases and acid–base status in juvenile sandbar shark (Carcharhinus plumbeus)

PubMed Central

Harter, T. S.; Morrison, P. R.; Mandelman, J. W.; Rummer, J. L.; Farrell, A. P.; Brill, R. W.; Brauner, C. J.

2015-01-01

Accurate measurements of blood gases and acid–base status require an array of sophisticated laboratory equipment that is typically not available during field research; such is the case for many studies on the stress physiology, ecology and conservation of elasmobranch fish species. Consequently, researchers have adopted portable clinical analysers that were developed for the analysis of human blood characteristics, but often without thoroughly validating these systems for their use on fish. The aim of our study was to test the suitability of the i-STAT system, the most commonly used portable clinical analyser in studies on fish, for analysing blood gases and acid–base status in elasmobranchs, over a broad range of conditions and using the sandbar shark (Carcharhinus plumbeus) as a model organism. Our results indicate that the i-STAT system can generate useful measurements of whole blood pH, and the use of appropriate correction factors may increase the accuracy of results. The i-STAT system was, however, unable to generate reliable results for measurements of partial pressure of oxygen (PO2) and the derived parameter of haemoglobin O2 saturation. This is probably due to the effect of a closed-system temperature change on PO2 within the i-STAT cartridge and the fact that the temperature correction algorithms used by i-STAT assume a human temperature dependency of haemoglobin–O2 binding; in many ectotherms, this assumption will lead to equivocal i-STAT PO2 results. The in vivo partial pressure of CO2 (PCO2) in resting sandbar sharks is probably below the detection limit for PCO2 in the i-STAT system, and the measurement of higher PCO2 tensions was associated with a large measurement error. In agreement with previous work, our results indicate that the i-STAT system can generate useful data on whole blood pH in fishes, but not blood gases. PMID:27293687

Air-breathing behavior, oxygen concentrations, and ROS defense in the swimbladders of two erythrinid fish, the facultative air-breathing jeju, and the non-air-breathing traira during normoxia, hypoxia and hyperoxia.

PubMed

Pelster, Bernd; Wood, Chris M; Jung, Ellen; Val, Adalberto L

2018-05-01

The jeju Hoplerythrinus unitaeniatus and the traira Hoplias malabaricus are two neighboring genera from the family of erythrinid fish, both possessing a two-chambered physostomous swimbladder. In the jeju the anterior section of the posterior bladder is highly vascularized, and the swimbladder is used for aerial respiration; the traira, in turn, is a water-breather that uses the swimbladder as a buoyancy organ and not for aerial oxygen uptake. Measurement of swimbladder oxygen partial pressure (PO 2 ) of fish kept at 26 °C in normoxic, hyperoxic (28-32 mg O 2 L - 1 ) or hypoxic (1-1.5 mg O 2 L - 1 ) water revealed constant values in traira swimbladder. Under normoxic conditions in the jeju swimbladder PO 2 was higher than in traira, and the PO 2 significantly increased under hyperoxic conditions, even in the absence of air breathing. In jeju, air-breathing activity increased significantly under hypoxic conditions. Hypoxic air-breathing activity was negatively correlated to swimbladder PO 2 , indicating that the swimbladder was intensely used for gas exchange under these conditions. In traira, the capacity of the ROS defense system, as assessed by measurement of activities of enzymes involved in ROS degradation and total glutathione (GSH + GSSG) concentration, was elevated after 4 h of hyperoxic and/or hypoxic exposure, although swimbladder PO 2 was not affected. In jeju, experiencing a higher variability in swimbladder PO 2 due to the air-breathing activity, only a reduced responsiveness of the ROS defense system to changing environmental PO 2 was detected.

Time-dependent middle ear pressure changes under general anaesthesia in children: N2O-O2 mixture versus air-oxygen mixture.

PubMed

Apan, A; Muluk, N Bayar; Güler, S; Budak, B

2013-01-01

The aim of this study was to investigate the effects of N2O-O2 mixture (Inspired O2 30%) on middle ear pressure (MEP) in children compared with the effects of an air-oxygen mixture (Inspired O2 50%). The study included thirty child patients who underwent general anaesthesia for different reasons, with the exception of ENT problems and ear interventions. They were randomly divided into two groups. Group 1 (15 children: 10 male and 5 female) received a N2O-O2 mixture (Inspired O2 30%); and group 2 (15 children: 10 male and 5 female) were given an air-oxygen mixture (Inspired O2 50%). MEP was measured using a portable impedance analyser before the operation (PreO),10 minutes after intubation (10AEn), 30 minutes after intubation (30AEn), 10 minutes before extubation (10BEx), 15 minutes after the operation (PO15), 30 minutes after the operation (PO30), 1 hour after the operation (PO1h) and 6 hours after the operation (PO6h). The pressure and compliance values were the same in groups 1 and 2. The pressure-time graphs for the two groups were different: in Group 2, MEP rose quickly at 10AEn and positive pressure values were seen in the middle ear. MEP then fell rapidly until the end of the surgery and lower and negative pressures (Mean -50 daPa) were observed at PO6h. In Group 1, MEP was elevated at 10AEn and positive pressure was found (but not as high as in Group 2). MEP then fell more slowly. In other words, positive pressure in the middle ear persisted longer and the middle ear was subjected to positive pressure and nitrogen over a longer period. Separate analyses were made in Groups 1 and 2 of pressure differences and of compliance values at eight measurement points using the Friedman test. Differences in pressure values were found to be statistically significant in both Group 1 (p = 0.000) and Group 2 (p = 0.000). In Group 1, all the 10AEn and 30AEn values were significantly higher than the PreO, PO30, PO1h and PO6h values. The 10BEx value was significantly higher than the PreO and PO1h values. The PO15 value was significantly higher than the PreO value. In Group 2, the PO6h value was significantly lower than the 10BEx, 10AEn and 30AEn values. The PO1h value was significantly lower than the 30AEn values. The MEP values increased in Group 1 in younger and taller children and in children receiving anaesthesia for shorter periods. MEP values increased in Group 2 in younger and taller children, and in heavier children. MEP values fell with the length of anaesthesia. In brief anaesthesia, nitrogen was not removed from the middle ear quickly in Group 1: middle ear pressure values were higher. The nitrous oxide remained in the middle ear longer and so the possibility of ear toxicity may increase. In Group 2, 50% O2 was rapidly absorbed and removed from the middle ear and so middle ear pressure was not as high. It may be concluded that air-oxygen mixture (Inspired O2 50%) anaesthesia should be recommended as being more reliable in tympanoplasties and other middle ear interventions than a N2O-O2 mixture (Inspired O2 30%).

Development enhances hypometabolism in northern elephant seal pups (Mirounga angustirostris)

PubMed Central

Tift, Michael S.; Ranalli, Elizabeth C.; Houser, Dorian S.; Ortiz, Rudy M.; Crocker, Daniel E.

2013-01-01

Summary Investigation into the development of oxygen storage capacity in air-breathing marine predators has been performed, but little is known about the development of regulatory factors that influence oxygen utilization. Strategies for efficiently using oxygen stores should enable marine predators to optimize time spent foraging underwater. We describe the developmental patterns of oxygen use during voluntary breath-holds in northern elephant seals (Mirounga angustirostris) at 2 and 7 weeks post-weaning. We measured 1) changes in oxygen consumption (VO2), and 2) changes in venous pH, partial pressure of oxygen (pO2), haemoglobin saturation (sO2), oxygen content (O2ct), partial pressure of carbon dioxide (pCO2), haematocrit (Hct) and total haemoglobin (tHb). To examine the effect of the dive response on the development of oxygen utilization, voluntary breath-hold experiments were conducted in and out of water. Suppression of VO2 during voluntary breath-holds increased significantly between 2 and 7 weeks post-weaning, reaching a maximum suppression of 53% below resting metabolic rate and 56% below Kleiber’s standard metabolic rate. From 2 to 7 weeks post-weaning, breath-hold VO2 was reduced by 52%. Between the two age classes, this equates to a mean breath-hold VO2 reduction of 16% from resting VO2. Breath-hold VO2 also declined with increasing breath-hold duration, but there was no direct effect of voluntary submergence on reducing VO2. Age did not influence rates of venous pO2 depletion during breath-holds. However, voluntary submergence did result in slower pO2 depletion rates when compared to voluntary terrestrial apnoeas. The differences in whole body VO2 during breath-holds (measured at recovery) and venous pO2 (reflective of tissue O2-use measured during breath-holds), likely reflects metabolic suppression in hypoxic, vasoconstricted tissues. Consistent pCO2 values at the end of all voluntary breath-holds (59.0 ± 0.7 mmHg) suggests the physiological cue for stimulating respiration in northern elephant seal pups is the accumulation of CO2. Oxygen storage capacity and metabolic suppression directly limit diving capabilities and may influence foraging success in low-weaning weight seals forced to depart to sea prior to achieving full developmental diving capacity. PMID:24187422

Mathematical modeling of human brain physiological data

NASA Astrophysics Data System (ADS)

Böhm, Matthias; Faltermeier, Rupert; Brawanski, Alexander; Lang, Elmar W.

2013-12-01

Recently, a mathematical model of the basic physiological processes regulating the cerebral perfusion and oxygen supply was introduced [Jung , J. Math. Biol.JMBLAJ0303-681210.1007/s00285-005-0343-5 51, 491 (2005)]. Although this model correctly describes the interdependence of arterial blood pressure (ABP) and intracranial pressure (ICP), it fails badly when it comes to explaining certain abnormal correlations seen in about 80% of the recordings of ABP together with ICP and the partial oxygen pressure (TiPO2) of the neuronal tissue, taken at an intensive care unit during neuromonitoring of patients with a severe brain trauma. Such recordings occasionally show segments, where the mean arterial blood pressure is correlated with the partial oxygen pressure in tissue but anticorrelated with the intracranial pressure. The origin of such abnormal correlations has not been fully understood yet. Here, two extensions to the previous approach are proposed which can reproduce such abnormal correlations in simulations quantitatively. Furthermore, as the simulations are based on a mathematical model, additional insight into the physiological mechanisms from which such abnormal correlations originate can be gained.

Targeted partial surface modification with nano-SiO2@Li2CoPO4F as high-voltage cathode material for LIBs

NASA Astrophysics Data System (ADS)

Chang, Caiyun; Huang, Zhipeng; Tian, Runsai; Jiang, Xinyu; Li, Chunsheng; Feng, Jijun

2017-10-01

Tuning whole/partial surface modification on cathode material with oxide material is a sought-after method to enhance the electrochemical performance in power storage field. Herein, nano-SiO2 targeted partial surface modified high voltage cathode material Li2CoPO4F has been successfully fabricated via a facile self-assembly process in silica dispersion at ambient temperature. With the aid of polar -OH groups attracted on the surface of SiO2 micelles, the nano-SiO2 preferentially nestle up along the borders and boundaries of Li2CoPO4F particles, where protection should be deployed with emphasis against the undesirable interactions between materials and electrolytes. Compared with pristine Li2CoPO4F, the SiO2 selectively modified Li2CoPO4F cathode materials, especially LCPF-3S, exhibit desirable electrochemical performances with higher discharge capacity, more outstanding cycle stability and favorable rate capability without any additional carbon involved. The greatly enhanced electrochemical properties can be attributed to the improved lithium-ion diffusion kinetics and structure tolerance during repeated lithiation/delithiation process. Such findings reveal a great potential of nano-SiO2 modified Li2CoPO4F as high energy cathode material for lithium ion batteries.

Development and Validation of Noninvasive Magnetic Resonance Relaxometry for the In Vivo Assessment of Tissue-Engineered Graft Oxygenation

PubMed Central

Einstein, Samuel A.; Weegman, Bradley P.; Firpo, Meri T.; Papas, Klearchos K.

2016-01-01

Techniques to monitor the oxygen partial pressure (pO2) within implanted tissue-engineered grafts (TEGs) are critically necessary for TEG development, but current methods are invasive and inaccurate. In this study, we developed an accurate and noninvasive technique to monitor TEG pO2 utilizing proton (1H) or fluorine (19F) magnetic resonance spectroscopy (MRS) relaxometry. The value of the spin-lattice relaxation rate constant (R1) of some biocompatible compounds is sensitive to dissolved oxygen (and temperature), while insensitive to other external factors. Through this physical mechanism, MRS can measure the pO2 of implanted TEGs. We evaluated six potential MRS pO2 probes and measured their oxygen and temperature sensitivities and their intrinsic R1 values at 16.4 T. Acellular TEGs were constructed by emulsifying porcine plasma with perfluoro-15-crown-5-ether, injecting the emulsion into a macroencapsulation device, and cross-linking the plasma with a thrombin solution. A multiparametric calibration equation containing R1, pO2, and temperature was empirically generated from MRS data and validated with fiber optic (FO) probes in vitro. TEGs were then implanted in a dorsal subcutaneous pocket in a murine model and evaluated with MRS up to 29 days postimplantation. R1 measurements from the TEGs were converted to pO2 values using the established calibration equation and these in vivo pO2 measurements were simultaneously validated with FO probes. Additionally, MRS was used to detect increased pO2 within implanted TEGs that received supplemental oxygen delivery. Finally, based on a comparison of our MRS data with previously reported data, ultra-high-field (16.4 T) is shown to have an advantage for measuring hypoxia with 19F MRS. Results from this study show MRS relaxometry to be a precise, accurate, and noninvasive technique to monitor TEG pO2 in vitro and in vivo. PMID:27758135

Development and Validation of Noninvasive Magnetic Resonance Relaxometry for the In Vivo Assessment of Tissue-Engineered Graft Oxygenation.

PubMed

Einstein, Samuel A; Weegman, Bradley P; Firpo, Meri T; Papas, Klearchos K; Garwood, Michael

2016-11-01

Techniques to monitor the oxygen partial pressure (pO 2 ) within implanted tissue-engineered grafts (TEGs) are critically necessary for TEG development, but current methods are invasive and inaccurate. In this study, we developed an accurate and noninvasive technique to monitor TEG pO 2 utilizing proton ( 1 H) or fluorine ( 19 F) magnetic resonance spectroscopy (MRS) relaxometry. The value of the spin-lattice relaxation rate constant (R 1 ) of some biocompatible compounds is sensitive to dissolved oxygen (and temperature), while insensitive to other external factors. Through this physical mechanism, MRS can measure the pO 2 of implanted TEGs. We evaluated six potential MRS pO 2 probes and measured their oxygen and temperature sensitivities and their intrinsic R 1 values at 16.4 T. Acellular TEGs were constructed by emulsifying porcine plasma with perfluoro-15-crown-5-ether, injecting the emulsion into a macroencapsulation device, and cross-linking the plasma with a thrombin solution. A multiparametric calibration equation containing R 1 , pO 2 , and temperature was empirically generated from MRS data and validated with fiber optic (FO) probes in vitro. TEGs were then implanted in a dorsal subcutaneous pocket in a murine model and evaluated with MRS up to 29 days postimplantation. R 1 measurements from the TEGs were converted to pO 2 values using the established calibration equation and these in vivo pO 2 measurements were simultaneously validated with FO probes. Additionally, MRS was used to detect increased pO 2 within implanted TEGs that received supplemental oxygen delivery. Finally, based on a comparison of our MRS data with previously reported data, ultra-high-field (16.4 T) is shown to have an advantage for measuring hypoxia with 19 F MRS. Results from this study show MRS relaxometry to be a precise, accurate, and noninvasive technique to monitor TEG pO 2 in vitro and in vivo.

Ab initio study of phase stability of NaZr{sub 2}(PO{sub 4}){sub 3} under pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chinnappan, Ravi; Kaur, Gurpreet; Panigrahi, B. K.

2016-05-23

The elastic constants of NaZr{sub 2}(PO{sub 4}){sub 3} were computed as a function of pressure through Density Functional Theory calculations. The behavior of elastic constants show that the rhombohedral (R-3c) NaZr{sub 2}(PO{sub 4}){sub 3} becomes unstable above 8 GPa and is driven by softening of C{sub 44} through one of the Born stability criteria. High pressure equation of state and enthalpy show further that the ambient rhombohedral (R-3c)) NaZr{sub 2}(PO{sub 4}){sub 3} transforms first to another rhombohedral (R3) phase and subsequently to LiZr{sub 2}(PO{sub 4}){sub 3}-type orthorhombic phase at pressures above 6 and 8 GPa respectively which are in agreement with recentmore » X-ray diffraction study.« less

In vivo measurement of the tissue oxygenation by time-resolved luminescence spectroscopy of protoporphyrin IX: strategies to minimize artefacts associated with photoproducts

NASA Astrophysics Data System (ADS)

Gerelli, Emmanuel; Huntosova, Veronika; Horvath, Denis; Wagnières, Georges

2017-02-01

The determination of the oxygen partial pressure (pO2) in real time in living biological tissues is of high interest for numerous therapeutics, including photodynamic therapy (PDT) and radiotherapy. The minimally invasive and real-time measurement of the pO2 also enables to obtain interesting fundamental information regarding the metabolic activities in cells and tissues. The development of time-resolved luminescence measurement (TRLM) methods combined with the availability of new oxygen-sensitive molecular probes is at the origin of the significant progress that have been achieved during these past decades to measure the pO2 in living organisms. These probes include porphyrins, such as aminolevulinic acid-induced protoporphyrin IX (PPIX), which is an approved photosensitizer. Using the photosensitizer to probe the pO2 is of high interest in PDT since the level of oxygen is measured at the precise location where the phototoxic mechanisms take place. However, PPIX has drawbacks to measure the pO2 by TRLM, including its significant photobleaching. Since the PPIX excitation during pO2 measurements leads to the generation of its photoproducts, we studied the impact of their luminescence on the measurement of the PPIX triplet state lifetime in solution and in vivo on the Chick's Chorioallantoic Membrane (CAM) model. We performed this study under various oxygen conditions. Our results indicate that perturbations induced by these photoproducts can be avoided if the PPIX luminescence is detected between 620 and 640 nm, or if PPIX is excited at 405 nm with light doses < 1 J/cm2.

Bridging the gap between chemistry, physiology, and evolution: quantifying the functionality of sperm whale myoglobin mutants.

PubMed

Dasmeh, Pouria; Kepp, Kasper P

2012-01-01

This work merges a large set of previously reported thermochemical data for myoglobin (Mb) mutants with a physiological model of O(2)-transport and -storage. The model allows a quantification of the functional proficiency of myoglobin (Mb) mutants under various physiological conditions, i.e. O(2)-consumption rate resembling workload, O(2) partial pressure resembling hypoxic stress, muscle cell size, and Mb concentration, resembling different organism-specific and compensatory variables. We find that O(2)-storage and -transport are distinct functions that rank mutants and wild type differently depending on O(2) partial pressure. Specifically, the wild type is near-optimal for storage at all conditions, but for transport only at severely hypoxic conditions. At normoxic conditions, low-affinity mutants are in fact better O(2)-transporters because they still have empty sites for O(2), giving rise to a larger [MbO(2)] gradient (more varying saturation curve). The distributions of functionality reveal that many mutants are near-neutral with respect to function, whereas only a few are strongly affected, and the variation in functionality increases dramatically at lower O(2) pressure. These results together show that conserved residues in wild type (WT) Mb were fixated under a selection pressure of low P(O2). Copyright © 2011 Elsevier Inc. All rights reserved.

Evidence for a pressure-induced spin transition in olivine-type LiFePO4 triphylite

NASA Astrophysics Data System (ADS)

Núñez Valdez, Maribel; Efthimiopoulos, Ilias; Taran, Michail; Müller, Jan; Bykova, Elena; McCammon, Catherine; Koch-Müller, Monika; Wilke, Max

2018-05-01

We present a combination of first-principles and experimental results regarding the structural and magnetic properties of olivine-type LiFePO4 under pressure. Our investigations indicate that the starting P b n m phase of LiFePO4 persists up to 70 GPa. Further compression leads to an isostructural transition in the pressure range of 70-75 GPa, inconsistent with a former theoretical study. Considering our first-principles prediction for a high-spin to low-spin transition of Fe2 + close to 72 GPa, we attribute the experimentally observed isostructural transition to a change in the spin state of Fe2 + in LiFePO4. Compared to relevant Fe-bearing minerals, LiFePO4 exhibits the largest onset pressure for a pressure-induced spin state transition.

Oxygen-coupled redox regulation of the skeletal muscle ryanodine receptor-Ca2+ release channel by NADPH oxidase 4

PubMed Central

Sun, Qi-An; Hess, Douglas T.; Nogueira, Leonardo; Yong, Sandro; Bowles, Dawn E.; Eu, Jerry; Laurita, Kenneth R.; Meissner, Gerhard; Stamler, Jonathan S.

2011-01-01

Physiological sensing of O2 tension (partial O2 pressure, pO2) plays an important role in some mammalian cellular systems, but striated muscle generally is not considered to be among them. Here we describe a molecular mechanism in skeletal muscle that acutely couples changes in pO2 to altered calcium release through the ryanodine receptor–Ca2+-release channel (RyR1). Reactive oxygen species are generated in proportion to pO2 by NADPH oxidase 4 (Nox4) in the sarcoplasmic reticulum, and the consequent oxidation of a small set of RyR1 cysteine thiols results in increased RyR1 activity and Ca2+ release in isolated sarcoplasmic reticulum and in cultured myofibers and enhanced contractility of intact muscle. Thus, Nox4 is an O2 sensor in skeletal muscle, and O2-coupled hydrogen peroxide production by Nox4 governs the redox state of regulatory RyR1 thiols and thereby governs muscle performance. These findings reveal a molecular mechanism for O2-based signaling by an NADPH oxidase and demonstrate a physiological role for oxidative modification of RyR1. PMID:21896730

Oxygen dependency of germinating Brassica seeds

NASA Astrophysics Data System (ADS)

Park, Myoung Ryoul; Hasenstein, Karl H.

2016-02-01

Establishing plants in space, Moon or Mars requires adaptation to altered conditions, including reduced pressure and composition of atmospheres. To determine the oxygen requirements for seed germination, we imbibed Brassica rapa seeds under varying oxygen concentrations and profiled the transcription patterns of genes related to early metabolism such as starch degradation, glycolysis, and fermentation. We also analyzed the activity of lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH), and measured starch degradation. Partial oxygen pressure (pO2) greater than 10% resulted in normal germination (i.e., protrusion of radicle about 18 hours after imbibition) but lower pO2 delayed and reduced germination. Imbibition in an oxygen-free atmosphere for three days resulted in no germination but subsequent transfer to air initiated germination in 75% of the seeds and the root growth rate was transiently greater than in roots germinated under ambient pO2. In hypoxic seeds soluble sugars degraded faster but the content of starch after 24 h was higher than at ambient oxygen. Transcription of genes related to starch degradation, α-amylase (AMY) and Sucrose Synthase (SUS), was higher under ambient O2 than under hypoxia. Glycolysis and fermentation pathway-related genes, glucose phosphate isomerase (GPI), 6-phosphofructokinase (PFK), fructose 1,6-bisphosphate aldolase (ALD), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate decarboxylase (PDC), LDH, and ADH, were induced by low pO2. The activity of LDH and ADH was the highest in anoxic seeds. Germination under low O2 conditions initiated ethanolic fermentation. Therefore, sufficient oxygen availability is important for germination before photosynthesis provides necessary oxygen and the determination of an oxygen carrying capacity is important for uniform growth in space conditions.

Optimization of the deposition conditions and structural characterization of Y1Ba2Cu3O(7-x) thin superconducting films

NASA Technical Reports Server (NTRS)

Chrzanowski, J.; Meng-Burany, S.; Xing, W. B.; Curzon, A. E.; Heinrich, B.; Irwin, J. C.; Cragg, R. A.; Zhou, H.; Habib, F.; Angus, V.

1995-01-01

Two series of Y1Ba2Cu3O(z) thin films deposited on (001) LaAl03 single crystals by excimer laser ablation under two different protocols have been investigated. The research has yielded well defined deposition conditions in terms of oxygen partial pressure p(O2) and substrate temperature of the deposition process Th, for the growth of high quality epitaxial films of YBCO. The films grown under conditions close to optimal for both j(sub c) and T(sub c) exhibited T(sub c) greater than or equal to 91 K and j(sub c) greater than or equal to 4 x 106 A/sq cm, at 77 K. Close correlations between the structural quality of the film, the growth parameters (p(O2), T(sub h)) and j(sub c) and T(sub c) have been found.

Supplemental Oxygen and Carbon Dioxide Each Increase Subcutaneous and Intestinal Intramural Oxygenation

PubMed Central

Ratnaraj, Jebadurai; Kabon, Barbara; Talcott, Michael R.; Sessler, Daniel I.

2005-01-01

Oxidative killing by neutrophils, a primary defense against surgical pathogens, is directly related to tissue oxygenation. We tested the hypothesis that supplemental inspired oxygen or mild hypercapnia (end-tidal PCO2 of 50 mmHg) improves intestinal oxygenation. Pigs (25±2.5 kg) were used in two studies in random order: 1) Oxygen Study — 30% vs. 100% inspired oxygen concentration at an end-tidal PCO2 of 40 mmHg, and 2) Carbon Dioxide Study — end-tidal PCO2 of 30 mmHg vs. 50 mmHg with 30% oxygen. Within each study, treatment order was randomized. Treatments were maintained for 1.5 hours; measurements were averaged over the final hour. A tonometer inserted in the subcutaneous tissue of the left upper foreleg measured subcutaneous oxygen tension. Tonometers inserted into the intestinal wall measured intestinal intramural oxygen tension from the small and large intestines. 100% oxygen administration doubled subcutaneous oxygen partial pressure (PO2) (57±10 to 107±48 mmHg, P=0.006) and large intestine intramural PO2 (53±14 to 118±72 mmHg, P=0.014); intramural PO2increased 40% in the small intestine (37±10 to 52±25 mmHg, P=0.004). An end-tidal PCO2 of 50 mmHg increased large intestinal PO2 approximately 16% (49±10 to 57±12 mmHg, P=0.039), while intramural PO2 increased by 45% in the small intestine (31±12 to 44±16 mmHg, P=0.002). Supplemental oxygen and mild hypercapnia each increased subcutaneous and intramural tissue PO2, with supplemental oxygen being most effective. PMID:15281531

The relative influence of hematocrit and red blood cell velocity on oxygen transport from capillaries to tissue

PubMed Central

Lücker, Adrien; Secomb, Timothy W.; Weber, Bruno; Jenny, Patrick

2016-01-01

Objective Oxygen transport to parenchymal cells occurs mainly at the microvascular level, and depends on convective red blood cell (RBC) flux, which is proportional in an individual capillary to the product of capillary hematocrit and red blood cell velocity. This study investigates the relative influence of these two factors on tissue oxygen partial pressure (Po2). Methods A simple analytical model is used to quantify the respective influences of hematocrit, RBC velocity and flow on tissue oxygenation around capillaries. Predicted tissue Po2 levels are compared with a detailed computational model. Results Hematocrit is shown to have a larger influence on tissue Po2 than RBC velocity. The effect of RBC velocity increases with distance from the arterioles. Good agreement between analytical and numerical results is obtained and the discrepancies are explained. Significant dependence of mass transfer coefficients on RBC velocity at low hematocrit is demonstrated. Conclusions For a given RBC flux in a capillary, the Po2 in the surrounding tissue increases with increasing hematocrit, as a consequence of decreasing intravascular resistance to diffusive oxygen transport from RBCs to tissue. These results contribute to understanding the effects of blood flow changes on oxygen transport, such as occur in functional hyperemia in the brain. PMID:27893186

The structural response of gadolinium phosphate to pressure

DOE PAGES

Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.; ...

2016-06-16

In this study, accurate elastic constants for gadolinium phosphate (GdPO 4) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO 4 determined under hydrostatic conditions, 128.1(8) GPa (K'=5.8(2)), is markedly different from that obtained with GdPO 4 under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. Finally, high pressure Raman and diffraction analysis indicate that the PO 4 tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO 4 structure is facilitated by bending/twisting of the Gd–O–P links that result inmore » increased distortion in the GdO 9 polyhedra.« less

Tissue oxygen measurement system

NASA Technical Reports Server (NTRS)

Soller, Babs R. (Inventor)

2004-01-01

A device and method in accordance with the invention for determining the oxygen partial pressure (PO.sub.2) of a tissue by irradiating the tissue with optical radiation such that the light is emitted from the tissue, and by collecting the reflected or transmitted light from the tissue to form an optical spectrum. A spectral processor determines the PO.sub.2 level in tissue by processing this spectrum with a previously-constructed spectral calibration model. The tissue may, for example, be disposed underneath a covering tissue, such as skin, of a patient, and the tissue illuminated and light collected through the skin. Alternatively, direct tissue illumination and collection may be effected with a hand-held or endoscopic probe. A preferred system also determines pH from the same spectrum, and the processor may determine critical conditions and issue warnings based on parameter values.

Defect phase diagram for doping of Ga2O3

NASA Astrophysics Data System (ADS)

Lany, Stephan

2018-04-01

For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association of dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO2) conditions. Considering further the stability constraints due to sublimation of molecular Ga2O, specific predictions of optimized pO2 and Si dopant concentrations are given. The incomplete passivation of dopant-defect complexes in β-Ga2O3 suggests a design rule for metastable doping above the solubility limit.

A potential new proxy for paleo-atmospheric pO2 from soil carbonate-hosted fluid inclusions applied to pristine Chinle soils from the Petrified Forest 1A core

NASA Astrophysics Data System (ADS)

Schaller, M. F.; Pettitt, E.; Knobbe, T.

2017-12-01

Proxies for the concentration of O2 in the ancient atmosphere are scarce. We have developed a potential new proxy for ancient atmospheric O2 content based on soil carbonate-hosted fluid inclusions. Soils are in continuous atmospheric communication, and relatively static equilibration between soil gas and atmospheric gas during formation, such that a predictable amount of atmosphere infiltrates a soil. This atmosphere is trapped by inclusions during carbonate precipitation. Here we show that carbonate hosted fluid inclusions are faithful recorders of soil gas concentrations and isotope ratios, and specifically that soil O2 partial pressures can be derived from the total gas contents of these inclusions. Using carbonate nodules from a span of depths in a modern vertisol near Dallas, TX, as a test case, we employ an online crushing technique to liberate gases from soil carbonates into a small custom-built quadrupole mass spectrometer where all gases are measured in real time. We quantify the total oxygen content of the gas using a matrix-matched calibration, and define each species as a partial pressure of the total gas released from the nodule. Atmospheric pO2 is very simply derived from the soil-nodule partial pressures by accounting for the static productivity of the soil (using a small correction based on the CO2 concentration). When corrected for aqueous solubility using Henry's Law, these soil-carbonate hosted gas results reveal soil O2 concentrations that are comparable to modern-day dry atmosphere. Armed with this achievement in modern soils, and as a test on the applicability of the approach to ancient samples, we successfully apply the new proxy to nodules from the Late Triassic Chinle formation from the Petrified Forest National Park Core, taken as part of the Colorado Plateau Coring Project. Analysis of soil O2 from soil gas monitoring wells paired with measurements from contemporaneous soil carbonate nodules is needed to precisely calibrate the new proxy.

The effect of hypoxia and hyperoxia on nucleoside triphosphate/inorganic phosphate, pO2 and radiation response in an experimental tumour model.

PubMed Central

Nordsmark, M.; Maxwell, R. J.; Horsman, M. R.; Bentzen, S. M.; Overgaard, J.

1997-01-01

This study has evaluated the effect of breathing 100% oxygen, carbogen and carbon monoxide (at 660 p.p.m.) on the bioenergetic and oxygenation status and the radiation response of 200-mm3 C3H mammary carcinomas grown in the feet of CDF mice. Bioenergetic status was assessed by 31P magnetic resonance spectroscopy (MRS) using a 7-tesla spectrometer with both short (2 s) and long (6 s) pulse repetition times. Tumour partial pressure of oxygen (PO2) was measured with an Eppendorf polarographic electrode; the oxygenation parameters were the median pO2 and fraction of pO2 values < or = 2.5 mmHg. The radiation response was estimated using a tumour growth delay assay (time to grow three times treatment volume). Carbon monoxide breathing decreased tumour pO2 and compromised the radiation response, but the beta-nucleoside triphosphate (NTP)/Pi ratio was unchanged. Both carbogen and oxygen (100%) increased tumour pO2 and beta-NTP/Pi and enhanced the radiation response, the effects being similar under the two gassing conditions and dependent on the gas breathing time. Thus, in this tumour model, 31P-MRS can detect hyperoxic changes, but because cells can remain metabolically active even at low oxygen tensions the beta-NTP/Pi did not correlate with low tissue oxygenation. An analysis of variance showed that gas breathing time induced a significant systematic effect on beta-NTP/Pi, the MRS pulse repetition time had a significant effect on beta-NTP/Pi change under hypoxic but not under hyperoxic conditions and the type of gas that was inhaled had a significant effect on beta-NTP/Pi. Images Figure 4 PMID:9400939

Pharmacological inhibition of DNA methylation attenuates pressure overload-induced cardiac hypertrophy in rats.

PubMed

Stenzig, Justus; Schneeberger, Yvonne; Löser, Alexandra; Peters, Barbara S; Schaefer, Andreas; Zhao, Rong-Rong; Ng, Shi Ling; Höppner, Grit; Geertz, Birgit; Hirt, Marc N; Tan, Wilson; Wong, Eleanor; Reichenspurner, Hermann; Foo, Roger S-Y; Eschenhagen, Thomas

2018-07-01

Heart failure is associated with altered gene expression and DNA methylation. De novo DNA methylation is associated with gene silencing, but its role in cardiac pathology remains incompletely understood. We hypothesized that inhibition of DNA methyltransferases (DNMT) might prevent the deregulation of gene expression and the deterioration of cardiac function under pressure overload (PO). To test this hypothesis, we evaluated a DNMT inhibitor in PO in rats and analysed DNA methylation in cardiomyocytes. Young male Wistar rats were subjected to PO by transverse aortic constriction (TAC) or to sham surgery. Rats from both groups received solvent or 12.5 mg/kg body weight of the non-nucleosidic DNMT inhibitor RG108, initiated on the day of the intervention. After 4 weeks, we analysed cardiac function by MRI, fibrosis with Sirius Red staining, gene expression by RNA sequencing and qPCR, and DNA methylation by reduced representation bisulphite sequencing (RRBS). RG108 attenuated the ~70% increase in heart weight/body weight ratio of TAC over sham to 47% over sham, partially rescued reduced contractility, diminished the fibrotic response and the downregulation of a set of genes including Atp2a2 (SERCA2a) and Adrb1 (beta1-adrenoceptor). RG108 was associated with significantly lower global DNA methylation in cardiomyocytes by ~2%. The differentially methylated pathways were "cardiac hypertrophy", "cell death" and "xenobiotic metabolism signalling". Among these, "cardiac hypertrophy" was associated with significant methylation differences in the group comparison sham vs. TAC, but not significant between sham+RG108 and TAC+RG108 treatment, suggesting that RG108 partially prevented differential methylation. However, when comparing TAC and TAC+RG108, the pathway cardiac hypertrophy was not significantly differentially methylated. DNMT inhibitor treatment is associated with attenuation of cardiac hypertrophy and moderate changes in cardiomyocyte DNA methylation. The potential mechanistic link between these two effects and the role of non-myocytes need further clarification. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of administration of water enriched in O2 by injection or electrolysis on transcutaneous oxygen pressure in anesthetized pigs.

PubMed

Charton, Antoine; Péronnet, François; Doutreleau, Stephane; Lonsdorfer, Evelyne; Klein, Alexis; Jimenez, Liliana; Geny, Bernard; Diemunsch, Pierre; Richard, Ruddy

2014-01-01

Oral administration of oxygenated water has been shown to improve blood oxygenation and could be an alternate way for oxygen (O2) supply. In this experiment, tissue oxygenation was compared in anesthetized pigs receiving a placebo or water enriched in O2 by injection or a new electrolytic process. Forty-two pigs randomized in three groups received either mineral water as placebo or water enriched in O2 by injection or the electrolytic process (10 mL/kg in the stomach). Hemodynamic parameters, partial pressure of oxygen in the arterial blood (PaO2), skin blood flow, and tissue oxygenation (transcutaneous oxygen pressure, or TcPO2) were monitored during 90 minutes of general anesthesia. Absorption and tissue distribution of the three waters administered were assessed using dilution of deuterium oxide. Mean arterial pressure, heart rate, PaO2, arteriovenous oxygen difference, and water absorption from the gut were not significantly different among the three groups. The deuterium to protium ratio was also similar in the plasma, skin, and muscle at the end of the protocol. Skin blood flow decreased in the three groups. TcPO2 slowly decreased over the last 60 minutes of the experiment in the three groups, but when compared to the control group, the values remained significantly higher in animals that received the water enriched in O2 by electrolysis. In this protocol, water enriched in O2 by electrolysis lessened the decline of peripheral tissue oxygenation. This observation is compatible with the claim that the electrolytic process generates water clathrates which trap O2 and facilitate O2 diffusion along pressure gradients. Potential applications of O2-enriched water include an alternate method of oxygen supply.

Effect of administration of water enriched in O2 by injection or electrolysis on transcutaneous oxygen pressure in anesthetized pigs

PubMed Central

Charton, Antoine; Péronnet, François; Doutreleau, Stephane; Lonsdorfer, Evelyne; Klein, Alexis; Jimenez, Liliana; Geny, Bernard; Diemunsch, Pierre; Richard, Ruddy

2014-01-01

Background Oral administration of oxygenated water has been shown to improve blood oxygenation and could be an alternate way for oxygen (O2) supply. In this experiment, tissue oxygenation was compared in anesthetized pigs receiving a placebo or water enriched in O2 by injection or a new electrolytic process. Methods Forty-two pigs randomized in three groups received either mineral water as placebo or water enriched in O2 by injection or the electrolytic process (10 mL/kg in the stomach). Hemodynamic parameters, partial pressure of oxygen in the arterial blood (PaO2), skin blood flow, and tissue oxygenation (transcutaneous oxygen pressure, or TcPO2) were monitored during 90 minutes of general anesthesia. Absorption and tissue distribution of the three waters administered were assessed using dilution of deuterium oxide. Results Mean arterial pressure, heart rate, PaO2, arteriovenous oxygen difference, and water absorption from the gut were not significantly different among the three groups. The deuterium to protium ratio was also similar in the plasma, skin, and muscle at the end of the protocol. Skin blood flow decreased in the three groups. TcPO2 slowly decreased over the last 60 minutes of the experiment in the three groups, but when compared to the control group, the values remained significantly higher in animals that received the water enriched in O2 by electrolysis. Conclusions In this protocol, water enriched in O2 by electrolysis lessened the decline of peripheral tissue oxygenation. This observation is compatible with the claim that the electrolytic process generates water clathrates which trap O2 and facilitate O2 diffusion along pressure gradients. Potential applications of O2-enriched water include an alternate method of oxygen supply. PMID:25210438

Fabrication of lead-free piezoelectric Li2CO3-added (Ba,Ca)(Ti,Sn)O3 ceramics under controlled low oxygen partial pressure and their properties

NASA Astrophysics Data System (ADS)

Noritake, Kouta; Sakamoto, Wataru; Yuitoo, Isamu; Takeuchi, Teruaki; Hayashi, Koichiro; Yogo, Toshinobu

2018-02-01

Reduction-resistant lead-free (Ba,Ca)(Ti,Sn)O3 piezoceramics with high piezoelectric constants were fabricated by optimizing the amount of Li2CO3 added. Oxygen partial pressure was controlled during the sintering of (Ba,Ca)(Ti,Sn)O3 ceramics in a reducing atmosphere using H2-CO2 gas. Enhanced grain growth and a high-polarization state after poling treatment were achieved by adding Li2CO3. Optimizing the amount of Li2CO3 added to (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics sintered under a low oxygen partial pressure resulted in improved piezoelectric properties while maintaining the high sintered density. The prepared Li2CO3-added ceramic samples had homogeneous microstructures with a uniform dispersion of each major constituent element. However, the residual Li content in the 3 mol % Li2CO3-added (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics after sintering was less than 0.3 mol %. Sintered bodies of this ceramic prepared in a CO2 (1.5%)-H2 (0.3%)/Ar reducing atmosphere (PO2 = 10-8 atm at 1350 °C), exhibited sufficient electrical resistivity and a piezoelectric constant (d 33) exceeding 500 pC/N. The piezoelectric properties of this nonreducible ceramic were comparable or superior to those of the same ceramic sintered in air.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, R.; Hauss, H.; Buchholz, F.; Melzner, F.

2015-10-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2 and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply considerably fuels bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a downregulation of ammonium excretion. Here we show that exposure to OMZ conditions can result in strong depression of respiration and ammonium excretion in calanoid copepods and euphausiids from the Eastern Tropical North Atlantic and the Eastern Tropical South Pacific. These physiological responses need to be taken into account when estimating DVM-mediated fluxes of carbon and nitrogen into OMZs.

High pressure experimental studies on Na3Fe(PO4)(CO3) and Na3Mn(PO4)(CO3): Extensive pressure behaviors of carbonophosphates family

NASA Astrophysics Data System (ADS)

Gao, Jing; Huang, Weifeng; Wu, Xiang; Qin, Shan

2018-04-01

Carbon-bearing phases in the Earth's interior have profound implications for the long-term Earth carbon cycle. Here we investigate high-pressure behaviors of carbonophosphates bonshtedtite Na3Fe(PO4)(CO3) and sidorenkite Na3Mn(PO4)(CO3) in diamond anvil cells up to ∼12 GPa at room temperature. Modifications in in situ synchrotron X-ray diffraction patterns and Raman spectra confirm the structural stability of carbonophosphates within the pressure region. Fitting the third-order Birch-Murnaghan equation of state to the volume compression curve, the isothermal bulk modulus parameters are obtained to be K0 = 56(1) GPa, K0' = 3.3(1), V0 = 303.3(3) Å3 for Na3Fe(PO4)(CO3) and K0 = 54(1) GPa, K0' = 3.4(1), V0 = 313.4(2) Å3 for Na3Mn(PO4)(CO3). Crystallographic axes exhibit an elastic anisotropy with a more compressible c-axis relative to the ab-plane. An inverse linear correlation between the K0 value and the ionic radius of M2+ (M = Mg, Fe, Mn) is well determined for carbonophosphates. The pressure-dependence responsiveness of [PO4] and [CO3] in carbonophosphates show a negative relationship to the M2+ radius. We also discussed the effect of [PO4] group on the structural variations and high-pressure behaviors of carbonates. Furthermore, the geochemical properties of carbonophosphates hold implications to diamond genesis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.

In this study, accurate elastic constants for gadolinium phosphate (GdPO 4) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO 4 determined under hydrostatic conditions, 128.1(8) GPa (K'=5.8(2)), is markedly different from that obtained with GdPO 4 under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. Finally, high pressure Raman and diffraction analysis indicate that the PO 4 tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO 4 structure is facilitated by bending/twisting of the Gd–O–P links that result inmore » increased distortion in the GdO 9 polyhedra.« less

In vivo observation of intracellular oximetry in perfluorocarbon-labeled glioma cells and chemotherapeutic response in the CNS using fluorine-19 MRI

PubMed Central

Kadayakkara, Deepak K.K.; Janjic, Jelena M.; Pusateri, Lisa B.; Young, Won-Bin; Ahrens, Eric T.

2010-01-01

Preclinical development of therapeutic agents against cancer could greatly benefit from noninvasive markers of tumor killing. Potentially, the intracellular partial pressure of oxygen (pO2) can be used as an early marker of anti-tumor efficacy. Here, the feasibility of measuring intracellular pO2 of CNS glioma cells in vivo using 19F magnetic resonance techniques is examined. Rat 9L glioma cells were labeled with perfluoro-15-crown-5-ether (PCE) ex vivo and then implanted into the rat striatum. 19F MRI was used to visualize tumor location in vivo. The mean 19F T1 of the implanted cells was measured using localized, single-voxel spectroscopy. The intracellular pO2 in tumor cells was determined from an in vitro calibration curve. The basal pO2 of 9L cells (day 3) was determined to be 45.3±5 mm Hg (n=6). Rats were then treated with a 1× LD10 dose of bischloroethylnitrosourea (BCNU) intravenously, and changes in intracellular pO2 were monitored. The pO2 increased significantly (p=0.042, paired T-test) to 141.8±3 mm Hg within 18 hours after BCNU treatment (day 4) and remained elevated (165±24 mm Hg) for at least 72 hours (day 6). Intracellular localization of the PCE emulsion in 9L cells before and after BCNU treatment was confirmed by histological examination and fluorescence microscopy. Overall, non-invasive 19F magnetic resonance techniques may provide a valuable preclinical tool for monitoring therapeutic response against CNS or other deep-seated tumors. PMID:20860007

Cherenkov excited phosphorescence-based pO2 estimation during multi-beam radiation therapy: phantom and simulation studies

NASA Astrophysics Data System (ADS)

Holt, Robert W.; Zhang, Rongxiao; Esipova, Tatiana V.; Vinogradov, Sergei A.; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

2014-09-01

Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15 mmHg for edge depths less than 10-20 mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction.

Cherenkov excited phosphorescence-based pO2 estimation during multi-beam radiation therapy: phantom and simulation studies.

PubMed

Holt, Robert W; Zhang, Rongxiao; Esipova, Tatiana V; Vinogradov, Sergei A; Glaser, Adam K; Gladstone, David J; Pogue, Brian W

2014-09-21

Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15 mmHg for edge depths less than 10-20 mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction.

Validation of the i-STAT system for the analysis of blood parameters in fish

PubMed Central

Harter, T. S.; Shartau, R. B.; Brauner, C. J.; Farrell, A. P.

2014-01-01

Portable clinical analysers, such as the i-STAT system, are increasingly being used for blood analysis in animal ecology and physiology because of their portability and easy operation. Although originally conceived for clinical application and to replace robust but lengthy techniques, researchers have extended the use of the i-STAT system outside of humans and even to poikilothermic fish, with only limited validation. The present study analysed a range of blood parameters [pH, haematocrit (Hct), haemoglobin (Hb), HCO3−, partial pressure of CO2 (PCO2), partial pressure of O2 (PO2), Hb saturation (sO2) and Na+ concentration] in a model teleost fish (rainbow trout, Oncorhynchus mykiss) using the i-STAT system (CG8+ cartridges) and established laboratory techniques. This methodological comparison was performed at two temperatures (10 and 20°C), two haematocrits (low and high) and three PCO2 levels (0.5, 1.0 and 1.5%). Our results indicate that pH was measured accurately with the i-STAT system over a physiological pH range and using the i-STAT temperature correction. Haematocrit was consistently underestimated by the i-STAT, while the measurements of Na+, PCO2, HCO3− and PO2 were variably inaccurate over the range of values typically found in fish. The algorithm that the i-STAT uses to calculate sO2 did not yield meaningful results on rainbow trout blood. Application of conversion factors to correct i-STAT measurements is not recommended, due to significant effects of temperature, Hct and PCO2 on the measurement errors and complex interactions may exist. In conclusion, the i-STAT system can easily generate fast results from rainbow trout whole blood, but many are inaccurate values. PMID:27293658

Myoglobin translational diffusion in rat myocardium and its implication on intracellular oxygen transport.

PubMed

Lin, Ping-Chang; Kreutzer, Ulrike; Jue, Thomas

2007-01-15

Current theory of respiratory control invokes a role of myoglobin (Mb)-facilitated O2 diffusion in regulating the intracellular O2 flux, provided Mb diffusion can compete effectively with free O2 diffusion. Pulsed-field gradient NMR methods have now followed gradient-dependent changes in the distinct 1H NMR gamma CH3 Val E11 signal of MbO2 in perfused rat myocardium to obtain the endogenous Mb translational diffusion coefficient (D(Mb)) of 4.24 x 10(-7) cm2 s(-1) at 22 degrees C. The D(Mb) matches precisely the value predicted by in vivo NMR rotational diffusion measurements of Mb and shows no orientation preference. Given values in the literature for the Krogh's free O2 diffusion coefficient (K0), myocardial Mb concentration and a partial pressure of O2 that half saturates Mb (P50), the analysis yields an equipoise diffusion P(O2) of 1.77 mmHg, where Mb and free O2 contribute equally to the O2 flux. In the myocardium, Mb-facilitated O2 diffusion contributes increasingly more than free O2 diffusion when the P(O2) falls below 1.77 mmHg. In skeletal muscle, the P(O2) must fall below 5.72 mmHg. Altering the Mb P50 induces modest change. Mb-facilitated diffusion has a higher poise in skeletal muscle than in myocardium. Because the basal P(O2) hovers around 10 mmHg, Mb does not have a predominant role in facilitating O2 transport in myocardium but contributes significantly only when cellular oxygen falls below the equipoise diffusion P(O2).

Intra-breath arterial oxygen oscillations detected by a fast oxygen sensor in an animal model of acute respiratory distress syndrome

PubMed Central

Formenti, F.; Chen, R.; McPeak, H.; Murison, P. J.; Matejovic, M.; Hahn, C. E. W.; Farmery, A. D.

2015-01-01

Background There is considerable interest in oxygen partial pressure (Po2) monitoring in physiology, and in tracking Po2 changes dynamically when it varies rapidly. For example, arterial Po2 (PaO2) can vary within the respiratory cycle in cyclical atelectasis (CA), where PaO2 is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these PaO2 oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS). Methods We developed a fibreoptic Po2 sensor (<200 µm diameter), suitable for human use, that has a fast response time, and can measure Po2 continuously in blood. By altering the inspired fraction of oxygen (FIO2) from 21 to 100% in four healthy animal models, we determined the linearity of the sensor's signal over a wide range of PaO2 values in vivo. We also hypothesized that the sensor could measure rapid intra-breath PaO2 oscillations in a large animal model of ARDS. Results In the healthy animal models, PaO2 responses to changes in FIO2 were in agreement with conventional intermittent blood-gas analysis (n=39) for a wide range of PaO2 values, from 10 to 73 kPa. In the animal lavage model of CA, the sensor detected PaO2 oscillations, also at clinically relevant PaO2 levels close to 9 kPa. Conclusions We conclude that these fibreoptic PaO2 sensors have the potential to become a diagnostic tool for CA in ARDS. PMID:25631471

[Correlation between arterial and venous blood gas analysis parameters in patients with acute exacerbation of chronic obstructive pulmonary disease].

PubMed

Novović, Miloš; Topić, Vesna

2012-01-01

Arterial blood gas (ABG) analyses have an important role in the assessment and monitoring of the metabolic and oxygen status of patients with acute exacerbation of chronic obstructive pulmonary disease (COPD). Arterial puncture could have a lot of adverse effects, while sampling of venous blood is simpler and is not so invasive. The aim of this study was to evaluate whether venous blood gas (VBG) values of pH, partial pressure of carbon dioxide (PCO2), partial oxygen pressure (PO2), bicarbonate (HCO3), and venous and arterial blood oxygen saturation (SO2) can reliably predict ABG levels in patients with acute exacerbation of COPD. Forty-seven patients with a prior diagnosis of COPD were included in this prospective study. The patients with acute exacerbation of this disease were examined at the General Hospital EMS Department in Prijepolje. ABG samples were taken immediately after venous sampling, and both were analyzed. The Pearson correlation coefficients between arterial and venous parameters were 0.828, 0.877, 0.599, 0.896 and 0.312 for pH, PCO2, PO2, HCO3 and SO2, respectively. The statistically significant correlation between arterial and venous pH, PCO2 and HCO3, values was found in patients with acute exacerbation of COPD (p<0.001). When we cannot provide arterial blood for analysis, venous values of the pH, Pv,CO2 and HCO3 parameters can be an alternative to their arterial equivalents in the interpretation of the metabolic status in patients with acute exacerbation of COPD, while the values of venous Pv,O, and Sv,O2 cannot be used as predictors in the assessment of oxygen status of such patients.

Identifying compatibility of lithium salts with LiFePO4 cathode using a symmetric cell

NASA Astrophysics Data System (ADS)

Tong, Bo; Wang, Jiawei; Liu, Zhenjie; Ma, Lipo; Zhou, Zhibin; Peng, Zhangquan

2018-04-01

The electrochemical performance of lithium-ion batteries is dominated by the interphase electrochemistry between the electrolyte and electrode materials. A multitude of efforts have been dedicated to the solid electrolyte interphase (SEI) formed on the anode. However, the interphase on the cathode, namely the cathode electrolyte interphase (CEI), is left aside, partially due to the fact that it is hard to single out the CEI considering the complicated anode-cathode inter-talk. Herein, a partially delithiated lithium iron phosphate (Li0.25FePO4) electrode is used as the anode. Owing to a high voltage plateau (≈3.45 V vs. Li/Li+), negligible reduction reactions of electrolyte occur on the L0.25FePO4 anode. Therefore, the CEI can be investigated exclusively. Using a LiFePO4|Li0.25FePO4 symmetric cell configuration, we scrutinize the compatibility of the electrolytes containing a wide spectrum of lithium salts, Li[(FSO2)(Cm F2m+1SO2)N] (m = 0, 1, 2, 4), with the LiFePO4, in both cycling and calendar tests. It is found that the Li[(FSO2)(n-C4F9SO2)N] (LiFNFSI)-based electrolyte exhibits the highest compatibility with LiFePO4.

Measuring Transcutaneous Oxygenation to Validate the Duration Required to Achieve Electrode Equilibration.

PubMed

Chiang, Nathaniel; Jain, Jitendra K; Sleigh, Jamie; Vasudevan, Thodur

2018-06-01

The transcutaneous oxygenation measurement (TCOM) system is useful in assessing tissue viability. There are no clear recommendations regarding the duration required for the electrode to equilibrate and reliably evaluate tissue oxygenation values. The objective of this study was to validate the duration required to achieve electrode equilibration in a clinical setting. Minute-by-minute recordings using TCOM (TCOM3; Radiometer Medical ApS, Brønshøj, Copenhagen) were obtained for 82 limbs in 50 participants. Twenty-five limbs were in patients with peripheral vascular disease; 30 were in patients with no known peripheral vascular disease; and 27 were in healthy volunteers. Transcutaneous partial pressure of oxygen and carbon dioxide (TcPO2 and TcPCO2) were recorded over a 15-minute period. Participants' TcPO2 decreased and TcPCO2 increased over time. Both changed in a nonlinear fashion, eventually settling at an "equilibrium" where the measurements became stable. The difference in proportional change of TcPO2 between minutes 14 and 15 was 0.8%, and for TcPCO2was 2.9%. Changes in TCOM measurements over time were similar among the 3 groups. This is the first study to target minute-by-minute variation in TcPO2 and TcPCO2 measurements. Recording for a minimum of 15 minutes allows a reliable period for the TCOM electrode to equilibrate to record absolute values and determine wound healing potential.

Interrelation of transport properties, defect structure and spin state of Ni3+ in La1.2Sr0.8Ni0.9Fe0.1O4+δ

NASA Astrophysics Data System (ADS)

Gilev, A. R.; Kiselev, E. A.; Zakharov, D. M.; Cherepanov, V. A.

2017-10-01

The total conductivity, Seebeck coefficient and oxygen non-stoichiometry for La1.2Sr0.8Ni0.9Fe0.1O4+δ have been measured vs temperature and oxygen partial pressure P(O2). The measurements were carried out at 800, 850, 900 and 950 °C within the P(O2) range of 10-5-0.21 atm. La1.2Sr0.8Ni0.9Fe0.1O4+δ was shown to be oxygen deficient in all temperature and P(O2) ranges studied. The calculated values of the partial molar enthalpy of oxygen depend very slightly on oxygen content (δ), indicating that La1.2Sr0.8Ni0.9Fe0.1O4+δ with the oxygen deficiency can be considered an ideal solution. The model of point defect equilibria in La1.2Sr0.8Ni0.9Fe0.1O4+δ has been proposed and fitted to experimental dependencies. Subsequent joint analysis of the defect structure and transport properties revealed that electron holes can coexist in both localized and quasi-delocalized states in the oxide: the former corresponded to high-spin state Ni3+ and the latter - to low-spin state Ni3+. The mobilities of localized electron holes were shown to be significantly lower in comparison to quasi-delocalized ones. The behavior of localized electron holes was explained in terms of a small polaron conduction mechanism; in contrast, quasi-delocalized electron holes were described in terms of a band conduction approach. The small polaron conduction mechanism was shown to be predominant in the Sr- and Fe-co-doped lanthanum nickelate.

Phase relationships and cation disorder in RE{sub 1+x}Ba{sub 2-x}Cu{sub 3}O{sub 7+{delta}}, RE = Pr, Nd, Sm, Gd

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramer, M.J.; Wu, H.; Dennis, K.W.

1995-12-31

Unlike Y123 which forms only a stoichiometric compound, the light arare earth elements (LRE) form a solid solution LRE{sub 1+x}Ba{sub 2-x}Cu{sub 3}O{sub 7+{delta}} (LRE123ss), with increasing substitution of the LRE{sup 3+} for the Ba{sup 2+} as the ionic radii of the LRE increases. The sub-solidus phase relationships around the LRE123ss change for La, Pr and Nd, but are similar for Sm and Gd. However, the solubility limit decreases with decreasing ionic radii. In addition, the solubility limits for Sm and Gd are strongly influenced by PO{sub 2} during high temperature annealing. The range of solubility is, for any given LREmore » system, strongly dependent on the oxygen partial pressure (PO{sub 2}) providing a new means by which to control the microstructure in the RE123 system.« less

[Simultaneous determinations of oxygen partial pressure in the scala tympani, electrocochleography and blood pressure measurements in noise stress in guinea pigs].

PubMed

Lamm, K; Lamm, C; Lamm, H; Schumann, K

1988-09-01

In 14 guinea pigs the pO2 in the perilymph of the scala tympani fell to 50%-80% of the original value during exposure to noise consisting of 4,000 Hz clicks with a repetition rate of 20/s, 100 dB CHL = 120 dB SPL p.e., repeated twice over a period of 24 minutes each time. For the measurements of the pO2 we used the thin 0.5 micron micro-coaxial needle electrode described by Baumgärtl and Luebbers, which was placed through the round-window membrane in the scala tympani to a depth of 600 micron. The simultaneously recorded CAP latency times were prolonged by 0.8 ms at a test loudness of 60 and 80 dB CHL. The amplitudes of the CM had declined by 60%-70% of the original values at a test loudness of 80 dB SPL p.e. The intra-arterial blood pressure in the common carotid artery of all animals remained constant. As the cortilymph spaces communicate with the perilymph of the scala tympani, our measured decline of pO2 in the perilymph could indicate a cortilymph hypoxia. During exposure to noise the oxygen-dependent Na+ and K+ pumps, which maintain the ion balance and function of the organ of Corti, can decompensate due to lack of oxygen. That would lead to a K+ contamination of the cortilymph and to an intracellular Na+ accumulation, which can cause microstructural damage (hair cell-cilia fusion, hair cell, synaptic and dendritic swelling, hair cell contraction and sustained depolarization), which would be reflected in the CMs and CAPs.

Solid state solubility of copper oxides in hydroxyapatite

NASA Astrophysics Data System (ADS)

Zykin, Mikhail A.; Vasiliev, Alexander V.; Trusov, Lev A.; Dinnebier, Robert E.; Jansen, Martin; Kazin, Pavel E.

2018-06-01

Samples containing copper oxide doped hydroxyapatite with the composition Ca10(PO4)6(CuxOH1-x-δ)2, x = 0.054 - 0.582, in the mixture with CuO/Cu2O were prepared by a solid-state high-temperature treatment at varying annealing temperatures and at different partial water vapor and oxygen pressures. The crystal structures of the apatite compounds were refined using powder X-ray diffraction patterns and the content of copper ions x in the apatite was determined. Copper ions enter exclusively into the apatite trigonal channels formally substituting protons of OH-groups and the hexagonal cell parameters grow approximately linearly with x, the channel volume mostly expanding while the remaining volume of the crystal lattice changing only slightly. The equilibrium copper content in the apatite increases drastically, by almost a factor of 10 with the annealing temperature rising from 800° to 1200°C. The reduction of the water partial pressure leads to a further increase of x, while the dependence of x on the oxygen partial pressure exhibits a maximum. The observed relations are consistent with the proposed chemical reactions implying the copper introduction is followed by the release of a considerable quantity of gaseous products - water and oxygen. The analysis of interatomic distances suggests that the maximum content of copper ions in the channel cannot exceed 2/3.

Thermodynamics of Palladium (Pd) and Tantalum (Ta) Relevant to Secondary Copper Smelting

NASA Astrophysics Data System (ADS)

Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S. H.; Reuter, M. A.

2017-02-01

The slag-to-metal distribution ratios of palladium (Pd), L_{{Pd}}^{s/m} , in the range of oxygen partial pressure ( pO2) from 10-10 to 10-7 atm at 1473 K to 1623 K (1200 °C to 1350 °C); distribution ratios of tantalum (Ta), L_{{Ta}}^{s/m} , in the range of pO2 from 10-16 to 10-12 atm at 1673 K and 1873 K (1400 °C and 1600 °C), have been determined in this study. The L_{{Pd}}^{s/m} in FeO x -CaO-SiO2-MgO and copper at 1573 K (1300 °C) and pO2 = 10-8 atm is dependant strongly on basicity of slag, i.e. (CaO + MgO)/SiO2 or optical basicity. The current results suggest that Pd presents in the FeO x -CaO-SiO2-MgO slag predominantly as Pd2+. The activity coefficient of PdO in the slag at 1573 K (1300 °C) and pO2 = 10-8 atm was calculated to be in the range of 3.89 × 10-3 to 2.63 × 10-2. The L_{{Pd}}^{s/m} was also found to increase with increasing of pO2 and with decreasing of temperature. It was observed that Ta mostly partition to slag phase and very small amount of Ta was found in liquid copper at the high temperature and reduced condition studied. It can be suggested that to promote recovery of palladium from Pd-containing e-waste, a slag with lower silica content and basic flux based, high temperature with reducing atmosphere, is highly desired particularly in secondary copper smelting.

Hypoxia induces a phase transition within a kinase signaling network in cancer cells.

PubMed

Wei, Wei; Shi, Qihui; Remacle, Francoise; Qin, Lidong; Shackelford, David B; Shin, Young Shik; Mischel, Paul S; Levine, R D; Heath, James R

2013-04-09

Hypoxia is a near-universal feature of cancer, promoting glycolysis, cellular proliferation, and angiogenesis. The molecular mechanisms of hypoxic signaling have been intensively studied, but the impact of changes in oxygen partial pressure (pO2) on the state of signaling networks is less clear. In a glioblastoma multiforme (GBM) cancer cell model, we examined the response of signaling networks to targeted pathway inhibition between 21% and 1% pO2. We used a microchip technology that facilitates quantification of a panel of functional proteins from statistical numbers of single cells. We find that near 1.5% pO2, the signaling network associated with mammalian target of rapamycin (mTOR) complex 1 (mTORC1)--a critical component of hypoxic signaling and a compelling cancer drug target--is deregulated in a manner such that it will be unresponsive to mTOR kinase inhibitors near 1.5% pO2, but will respond at higher or lower pO2 values. These predictions were validated through experiments on bulk GBM cell line cultures and on neurosphere cultures of a human-origin GBM xenograft tumor. We attempt to understand this behavior through the use of a quantitative version of Le Chatelier's principle, as well as through a steady-state kinetic model of protein interactions, both of which indicate that hypoxia can influence mTORC1 signaling as a switch. The Le Chatelier approach also indicates that this switch may be thought of as a type of phase transition. Our analysis indicates that certain biologically complex cell behaviors may be understood using fundamental, thermodynamics-motivated principles.

Research Report: Intermittent hypobaric hypoxia and hyperbaric oxygen on GAP-43 in the rat carotid body.

PubMed

Peng, Zhengwu; Fan, Juan; Liu, Ling; Kuang, Fang; Xue, Fen; Wang, Bairen

2015-01-01

Adaptive changes in the carotid body (CB) including the expression of the growth-associated protein-43 (GAP-43) have been studied in response to low, but not high, oxygen exposure. Expression of GAP-43 in the CB of rats under different atmospheric pressures and oxygen partial pressure (PO2) conditions was investigated. Mature male Sprague-Dawley rats were exposed to intermittent hypobaric hypoxia (IHH, 0, 1, 2 and 3 weeks), intermittent hyperbaric oxygen (IHBO2, 0, 1, 5 and 10 days, sacrificed six hours or 24 hours after the last HBO2 exposure), and intermittent hyperbaric normoxia (IHN, same treatment pattern as IHBO2). GAP-43 was highly expressed (mainly in type I cells) in the CB of normal rats. IHH u-regulated GAP-43 expression in the CB with significant differences (immunohistochemical staining [IHC]: F(3,15)=40.64, P < 0.01; western blot [WB]: F(3,16) = 53.52, P < 0.01) across the subgroups. GAP-43 expression in the CB was inhibited by IHBO2 (controls vs. IHBO2 groups, IHC: F(6,30) = 15.85, P < 0.01; WB: F(6,29) = 15.95, P < 0.01). No detectable changes in GAP-43 expression were found for IHN. These findings indicated that different PO2 conditions, but not air pressures, played an important role in the plasticity of the CB, and that GAP-43 might be a viable factor for the plasticity of the CB.

Oxygen transport and pyrite oxidation in unsaturated coal-mine spoil

USGS Publications Warehouse

Guo, Weixing; Cravotta, Charles A.

1996-01-01

An understanding of the mechanisms of oxygen (02) transport in unsaturated mine spoil is necessary to design and implement effective measures to exclude 02 from pyritic materials and to control the formation of acidic mine drainage. Partial pressure of oxygen (Po2) in pore gas, chemistry of pore water, and temperature were measured at different depths in unsaturated spoil at two reclaimed surface coal mines in Pennsylvania. At mine 1, where spoil was loose, blocky sandstone, Po2 changed little with depth, decreasing from 21 volume percent (vol%) at the ground surface to a minimum of about 18 vol% at 10 m depth. At mine 2, where spoil was compacted, friable shale, Po2 decreased to less than 2 vol% at depth of about 10 m. Although pore-water chemistry and temperature data indicate that acid-forming reactions were active at both mines, the pore-gas data indicate that mechanisms for 0 2 transport were different at each mine. A numerical model was developed to simulate 02 transport and pyrite oxidation in unsaturated mine spoil. The results of the numerical simulations indicate that differences in 02 transport at the two mines can be explained by differences in the air permeability of spoil. Po2 changes little with depth if advective transport of 02 dominates as at mine 1, but decreases greatly with depth if diffusive transport of 02 dominates, as in mine 2. Model results also indicate that advective transport becomes significant if the air permeability of spoil is greater than 10-9 m2, which is expected for blocky sandstone spoil. In the advective-dominant system, thermally-induced convective air flow, as a consequence of the exothermic oxidation of pyrite, supplies the 02 to maintain high Po2 within the deep unsaturated zone.

Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications

PubMed Central

Epel, Boris; Sundramoorthy, Subramanian V.; Barth, Eugene D.; Mailer, Colin; Halpern, Howard J.

2011-01-01

Purpose: The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging. Methods: Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three-dimensional images of a narrow linewidth, water soluble, nontoxic oxygen-sensitive trityl molecule OX063 in vitro and in vivo. The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies. Results: A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above∼100 torr, CW performed better. The images produced by both methodologies showed pO2 distributions with similar mean values. However, ESE images demonstrated superior performance in low pO2 regions while missing voxels in high pO2 regions. Conclusions: ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors. PMID:21626937

Intrinsic and spatially nonuniform ferromagnetism in Co-doped ZnO films

NASA Astrophysics Data System (ADS)

Tseng, L. T.; Suter, A.; Wang, Y. R.; Xiang, F. X.; Bian, P.; Ding, X.; Tseng, A.; Hu, H. L.; Fan, H. M.; Zheng, R. K.; Wang, X. L.; Salman, Z.; Prokscha, T.; Suzuki, K.; Liu, R.; Li, S.; Morenzoni, E.; Yi, J. B.

2017-09-01

Co doped ZnO films have been deposited by a laser-molecular beam epitaxy system. X-ray diffraction and UV spectra analysis show that Co effectively substitutes the Zn site. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy analysis indicate that there are no clusters. Co dopants are uniformly distributed in ZnO film. Ferromagnetic ordering is observed in all samples deposited under an oxygen partial pressure, PO2=10-3 , 10-5, and 10-7 torr, respectively. However, the magnetization of PO2=10-3 and 10-5 is very small at room temperature. At low temperature, the ferromagnetic ordering is enhanced. Muon spin relaxation (μ SR ) measurements confirm the ferromagnetism in all samples, and the results are consistent with magnetization measurements. From μ SR and TEM analysis, the film deposited under PO2=10-7 torr shows intrinsic ferromagnetism. However, the volume fraction of the ferromagnetism phase is approximately 70%, suggesting that the ferromagnetism is not carrier mediated. Resistivity versus temperature measurements indicate Efros variable range hopping dominates the conductivity. From the above results, we can confirm that a bound magnetic polaron is the origin of the ferromagnetism.

Defect phase diagram for doping of Ga 2O 3

DOE PAGES

Lany, Stephan

2018-04-01

For the case of n-type doping of β-Ga 2O 3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO 2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association ofmore » dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO 2) conditions. Considering further the stability constraints due to sublimation of molecular Ga 2O, specific predictions of optimized pO 2 and Si dopant concentrations are given. To conclude, the incomplete passivation of dopant-defect complexes in β-Ga 2O 3 suggests a design rule for metastable doping above the solubility limit.« less

Defect phase diagram for doping of Ga 2O 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lany, Stephan

For the case of n-type doping of β-Ga 2O 3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO 2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association ofmore » dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO 2) conditions. Considering further the stability constraints due to sublimation of molecular Ga 2O, specific predictions of optimized pO 2 and Si dopant concentrations are given. To conclude, the incomplete passivation of dopant-defect complexes in β-Ga 2O 3 suggests a design rule for metastable doping above the solubility limit.« less

Defect Chemistry of " BaCuO2" I. Oxygen Non -Stoichiometry, Cation Molecularity and X-ray Diffraction Determinations

NASA Astrophysics Data System (ADS)

Spinolo, G.; Anselmi-Tamburini, U.; Arimondi, M.; Ghigna, P.; Flor, G.

1995-11-01

"BaCuO2" is the key intermediate in the synthesis of the Ba2YCu3O7-δ superconductor. Its very complex crystal structure is able to accommodate a large change in oxygen content. Oxygen non-stoichiometry of "BaCuO2" materials with 1:1 and 88:90 (Ba :Cu) molecularity has been investigated by polythermal X-ray powder diffraction coupled with isobaric-isothermal gravimetry determinations under different temperature and oxygen partial pressure conditions [300≤ T≤ 820 °C, 1 ≥ P(O2) ≥ 3 • 10-3 atm]. The 1:1 composition does not give well reproducible results, thus suggesting its polyphasic nature, at least in part of the investigated range. The results for the 88:90 ≅ 0.98 (Ba :Cu) composi­ tion are well reproducible and show that the material is single phase. Ba0.98CuO1.98 + δ is oxygen over-stoichiometric in the whole investigated [T, P(O2)] range, with a maximum value δ˜0.21. A Rietveld X-ray profile fitting is in agreement with previous single-crystal data. The trend of δ vs. P(O2) is consistent with the presence of oxygen interstitial defects on (possibly different) crystallographic sites.

Propionyl-L-carnitine improves endothelial function, microcirculation and pain management in critical limb ischemia.

PubMed

De Marchi, S; Zecchetto, S; Rigoni, A; Prior, M; Fondrieschi, L; Scuro, A; Rulfo, F; Arosio, E

2012-10-01

Chronic critical limb ischemia (CLI) is a severe condition of hypo-perfusion of lower limbs, which is associated with inflammation and a pro-coagulative state. It is a disease at high risk of amputation and cardiovascular death. Propionyl-L-carnitine (PLC) is efficacious in improving pain free walking distance in peripheral arterial disease with claudication; it also exerts favorable effects on the arterial wall and on endothelial function. The purpose of this study was to evaluate the effects of PLC on microcirculation, endothelial function and pain relief in patients affected by CLI not suitable for surgical intervention. We enrolled 48 patients with CLI. Patients were randomized into two groups: the first group was treated with PLC, the second was treated with saline solution. All of them underwent the following tests: laser Doppler flowmetry at the forefoot at rest and after ischemia, trans cutaneous oxygen partial pressure and carbon dioxide partial pressure at the forefoot at rest and after ischemia, endothelium dependent dilation of the brachial artery. All tests were repeated after treatments. Pain was assessed by visual analog pain scale. Endothelium dependent dilation increased after PLC (9.5 ± 3.2 vs 4.9 ± 1.4 %; p < 0.05). Post-ischemic peak flow with laser-Doppler flow increased after PLC. TcPO2 increased, while TcPCO2 decreased after PLC; CO2 production decreased after PLC. VAS showed a significant reduction in pain perception after active treatment. In CLI patients, PLC can improve microcirculation (post ischemic hyperemia, TcPO2 and TcPCO2 production). PLC also enhances endothelium dependent dilation and reduces analgesic consumption and pain perception.

Design of Plant Gas Exchange Experiments in a Variable Pressure Growth Chamber

NASA Technical Reports Server (NTRS)

Corey, Kenneth A.

1996-01-01

Sustainable human presence in extreme environments such as lunar and martian bases will require bioregenerative components to human life support systems where plants are used for generation of oxygen, food, and water. Reduced atmospheric pressures will be used to minimize mass and engineering requirements. Few studies have assessed the metabolic and developmental responses of plants to reduced pressure and varied oxygen atmospheres. The first tests of hypobaric pressures on plant gas exchange and biomass production at the Johnson Space Center will be initiated in January 1996 in the Variable Pressure Growth Chamber (VPGC), a large, closed plant growth chamber rated for 10.2 psi. Experiments were designed and protocols detailed for two complete growouts each of lettuce and wheat to generate a general database for human life support requirements and to answer questions about plant growth processes in reduced pressure and varied oxygen environments. The central objective of crop growth studies in the VPGC is to determine the influence of reduced pressure and reduced oxygen on the rates of photosynthesis, dark respiration, evapotranspiration and biomass production of lettuce and wheat. Due to the constraint of one experimental unit, internal controls, called pressure transients, will be used to evaluate rates of CO2 uptake, O2 evolution, and H2O generation. Pressure transients will give interpretive power to the results of repeated growouts at both reduced and ambient pressures. Other experiments involve the generation of response functions to partial pressures of O2 and CO2 and to light intensity. Protocol for determining and calculating rates of gas exchange have been detailed. In order to build these databases and implement the necessary treatment combinations in short time periods, specific requirements for gas injections and removals have been defined. A set of system capability checks will include determination of leakage rates conducted prior to the actual crop growouts. Schedules of experimental events for lettuce and wheat are outlined and include replications in time of diurnal routines, pressure transients, variable pO2, pO2/pCO2 ratio, and light intensity responses.

Pressure induced phase transformations in NaZr{sub 2}(PO{sub 4}){sub 3} studied by X-ray diffraction and Raman spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamali, K.; Ravindran, T.R., E-mail: trr@igcar.gov.in; Chandra Shekar, N.V.

2015-01-15

Raman spectroscopic and x-ray diffraction measurements on NaZr{sub 2}(PO{sub 4}){sub 3} were carried out up to 30 GPa at close intervals of pressure, revealing two structural phase transformations around 5 and 6.6 GPa. The second phase at 5.4 GPa is indexed to R3 space group similar to that of RbTi{sub 2}(PO{sub 4}){sub 3}. Bulk modulus decreases abruptly from 53 GPa (B′=4) to 36 GPa (B′=4) in the second phase above 5 GPa. The structure of the phase III at 8.2 GPa is indexed as orthorhombic similar to the case of high temperature phase of monoclinic LiZr{sub 2}(PO{sub 4}){sub 3}. Bulkmore » modulus of this phase III is found to be 65 GPa (B′=4), which is higher than that of the ambient phase. In high pressure Raman studies, modes corresponding to 72 and 112 cm{sup −1} soften in the ambient phase whereas around 5 GPa, the ones at 60, 105, 125 and 190 cm{sup −1} soften with pressure contributing negatively to overall thermal expansion. - Graphical abstract: High pressure study of NaZr{sub 2}(PO{sub 4}){sub 3} shows a reversible phase transition from R-3c to R3 structure at 5 GPa accompanied by an increase in compressibility signaling a polyhedral tilt transition. - Highlights: • NaZr{sub 2}(PO{sub 4}){sub 3} undergoes two reversible phase transitions at 5 and 6.7 GPa. • The transition at 5 is from rhombohedral R-3c to R3 structure. • Bulk modulus of NaZr{sub 2}(PO{sub 4}){sub 3} is lower than that for the isostructural RbTi{sub 2}(PO{sub 4}){sub 3.} • Compressibility increases with substitution of a smaller cation (Na). • Zr-translational and PO{sub 4} librational modes contribute to phase transition.« less

Oxidation Potentials in Matte Smelting of Copper and Nickel

NASA Astrophysics Data System (ADS)

Matousek, Jan W.

2014-09-01

The oxidation potential, given as the base-ten logarithm of the oxygen partial pressure in bars and the temperature [log pO2/ T, °C], defines the state of oxidation of pyrometallurgical extraction and refining processes. This property varies from copper making, [-6/1150]; to lead/zinc smelting, [-10/1200]; to iron smelting, [-13/1600]. The current article extends the analysis to the smelting of copper and nickel/copper sulfide concentrates to produce mattes of the type Cu(Ni)FeS(O) and iron silicate slags, FeOxSiO2—with oxidation potentials of [-7.5/1250].

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heffernan, Karina M.; Ross, Nancy L., E-mail: nross@vt.edu; Spencer, Elinor C.

Accurate elastic constants for gadolinium phosphate (GdPO{sub 4}) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO{sub 4} determined under hydrostatic conditions, 128.1(8) GPa (K′=5.8(2)), is markedly different from that obtained with GdPO{sub 4} under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. High pressure Raman and diffraction analysis indicate that the PO{sub 4} tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO{sub 4} structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in themore » GdO{sub 9} polyhedra. - Graphical abstract: A high-pressure single crystal diffraction study of GdPO{sub 4} with the monazite structure is presented. The elastic behaviour of rare-earth phosphates are believed to be sensitive to shear forces. The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. Compression of the structure is facilitated by bending/twisting of the Gd−O−P links that result in increased distortion in the GdO{sub 9} polyhedra. Display Omitted - Highlights: • The elastic responses of rare-earth phosphates are sensitive to shear forces. • The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. • Twisting of the inter-polyhedral links allows compression of the GdPO{sub 4} structure. • Changes to the GdO{sub 9} polyhedra occur in response to pressure (<7.0 GPa).« less

Vibrational spectroscopy of the phosphate mineral lazulite--(Mg, Fe)Al2(PO4)2·(OH)2 found in the Minas Gerais, Brazil.

PubMed

Frost, Ray L; Xi, Yunfei; Beganovic, Martina; Belotti, Fernanda Maria; Scholz, Ricardo

2013-04-15

This research was done on lazulite samples from the Gentil mine, a lithium bearing pegmatite located in the municipality of Mendes Pimentel, Minas Gerais, Brazil. Chemical analysis was carried out by electron microprobe analysis and indicated a magnesium rich phase with partial substitution of iron. Traces of Ca and Mn, (which partially replaced Mg) were found. The calculated chemical formula of the studied sample is: (Mg0.88, Fe0.11)Al1.87(PO4)2.08(OH)2.02. The Raman spectrum of lazulite is dominated by an intense sharp band at 1060 cm(-1) assigned to PO stretching vibrations of of tetrahedral [PO4] clusters presents into the HPO4(2-) units. Two Raman bands at 1102 and 1137 cm(-1) are attributed to both the HOP and PO antisymmetric stretching vibrations. The two infrared bands at 997 and 1007 cm(-1) are attributed to the ν1PO4(3-) symmetric stretching modes. The intense bands at 1035, 1054, 1081, 1118 and 1154 cm(-1) are assigned to the ν3PO4(3-) antisymmetric stretching modes from both the HOP and tetrahedral [PO4] clusters. A set of Raman bands at 605, 613, 633 and 648 cm(-1) are assigned to the ν4 out of plane bending modes of the PO4, HPO4 and H2PO4 units. Raman bands observed at 414, 425, 460, and 479 cm(-1) are attributed to the ν2 tetrahedral PO4 clusters, HPO4 and H2PO4 bending modes. The intense Raman band at 3402 and the infrared band at 3403 cm(-1) are assigned to the stretching vibration of the OH units. A combination of Raman and infrared spectroscopy enabled aspects of the molecular structure of the mineral lazulite to be understood. Copyright © 2013 Elsevier B.V. All rights reserved.

Tanreqing injection combined with conventional Western medicine for acute exacerbations of chronic obstructive pulmonary disease: a systematic review.

PubMed

Zhong, Yunqing; Mao, Bing; Wang, Gang; Fan, Tao; Liu, Xuemei; Diao, Xiang; Fu, Juanjuan

2010-12-01

In China, most patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) are usually treated with Tanreqing injection plus conventional Western medicine. However, the value of its use remains uncertain. The objective of this systematic review is to compare the efficacy of Tanreqing injection plus conventional Western medicine with that of conventional Western medicine alone (therapy A versus therapy B, respectively) in the management of acute exacerbations of COPD. Literature retrieval was conducted using the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE,(®) EMBASE, Chinese Biomedical Database (CBM), and other electronically available databases from respective inception to August 2009. In addition, manual search of some traditional Chinese journals was performed to identify potential studies. Review authors independently extracted the trial data and assessed the quality of each trial. The following outcomes were evaluated: (1) forced expiratory volume in 1 second as a percentage of the predicted value; (2) arterial partial pressure of oxygen (Po(2)); (3) arterial partial pressure of carbon dioxide (Pco(2)); (4) length of hospital stay; (5) marked efficacy rate; (6) interleukin-8; and (7) adverse events. Based on the search strategy, 14 trials involving 954 patients were finally included. Our results showed that compared with therapy B, therapy A improved Po(2), clinical efficacy, and lung function, reduced Pco(2), shortened the length of hospital stay, and was thus more therapeutically beneficial. No serious adverse events were reported. Within the limitations of this systematic review, we can conclude that compared with therapy B, therapy A may provide more benefits for patients with acute exacerbations of COPD. Further large-scale high-quality trials are warranted.

Phase Equilibria of ``Cu2O''-``FeO''-CaO-MgO-Al2O3 Slags at PO2 of 10-8.5 atm in Equilibrium with Metallic Copper for a Copper Slag Cleaning Production

NASA Astrophysics Data System (ADS)

Henao, Hector M.; Pizarro, Claudio; Font, Jonkion; Moyano, Alex; Hayes, Peter C.; Jak, Evgueni

2010-12-01

Limited data are available on phase equilibria of the multicomponent slag system at the oxygen partial pressures used in the copper smelting, converting, and slag-cleaning processes. Recently, experimental procedures have been developed and have been applied successfully to characterize several complex industrial slags. The experimental procedures involve high-temperature equilibration on a substrate and quenching followed by electron probe X-ray microanalysis. This technique has been used to construct the liquidus for the “Cu2O”-“FeO”-SiO2-based slags with 2 wt pct of CaO, 0.5 wt pct of MgO, and 4.0 wt pct of Al2O3 at controlled oxygen partial pressures in equilibrium with metallic copper. The selected ranges of compositions and temperatures are directly relevant to the copper slag-cleaning processes. The new experimental equilibrium results are presented in the form of ternary sections and as a liquidus temperature vs Fe/SiO2 weight ratio diagram. The experimental results are compared with the FactSage thermodynamic model calculations.

Thin-film nano-thermogravimetry applied to praseodymium-cerium oxide films at high temperatures

NASA Astrophysics Data System (ADS)

Schröder, Sebastian; Fritze, Holger; Bishop, Sean; Chen, Di; Tuller, Harry L.

2018-05-01

High precision measurements of oxygen nonstoichiometry δ in thin film metal oxides MaOb±δ at elevated temperatures and controlled oxygen partial pressures pO2 are reported with the aid of resonant microbalances. The resonant microbalances applied here consisted of y-cut langasite (La3Ga5SiO14) and CTGS (Ca3TaGa3Si2O14) piezoelectric resonators, operated in the thickness shear mode at ˜5 MHz. Measurements of variations in δ of Pr0.1Ce0.9O2-δ (PCO) films are reported for the oxygen partial pressure range from 10-8 bar to 0.2 bar at 700 °C, and these results were found to be in good agreement with previously reported oxygen nonstoichiometry δ data derived from chemical capacitance studies. The PCO thin-films were deposited via pulsed laser deposition on both sides of the resonators, whose series resonance frequency was tracked, converted into mass changes and, finally, into nonstoichiometry. The nonstoichiometry was observed to reach a plateau as the oxygen partial pressure dropped below about 10-5 bar, the behavior being attributed to the full reduction of Pr to the trivalent state. These resonators enable stable operation up to temperatures above 1000 °C, thereby maintaining high mass resolution suitable for determining oxygen nonstoichiometry variations in thin films deposited on such resonators. For the given experimental conditions, a mass resolution of ˜50 ng was achieved at 700 °C with the CTGS resonator.

Hypoxia induces a phase transition within a kinase signaling network in cancer cells

PubMed Central

Wei, Wei; Shi, Qihui; Remacle, Francoise; Qin, Lidong; Shackelford, David B.; Shin, Young Shik; Mischel, Paul S.; Levine, R. D.; Heath, James R.

2013-01-01

Hypoxia is a near-universal feature of cancer, promoting glycolysis, cellular proliferation, and angiogenesis. The molecular mechanisms of hypoxic signaling have been intensively studied, but the impact of changes in oxygen partial pressure (pO2) on the state of signaling networks is less clear. In a glioblastoma multiforme (GBM) cancer cell model, we examined the response of signaling networks to targeted pathway inhibition between 21% and 1% pO2. We used a microchip technology that facilitates quantification of a panel of functional proteins from statistical numbers of single cells. We find that near 1.5% pO2, the signaling network associated with mammalian target of rapamycin (mTOR) complex 1 (mTORC1)—a critical component of hypoxic signaling and a compelling cancer drug target—is deregulated in a manner such that it will be unresponsive to mTOR kinase inhibitors near 1.5% pO2, but will respond at higher or lower pO2 values. These predictions were validated through experiments on bulk GBM cell line cultures and on neurosphere cultures of a human-origin GBM xenograft tumor. We attempt to understand this behavior through the use of a quantitative version of Le Chatelier’s principle, as well as through a steady-state kinetic model of protein interactions, both of which indicate that hypoxia can influence mTORC1 signaling as a switch. The Le Chatelier approach also indicates that this switch may be thought of as a type of phase transition. Our analysis indicates that certain biologically complex cell behaviors may be understood using fundamental, thermodynamics-motivated principles. PMID:23530221

Effect on lipopolysaccharide structure of aeration during growth of a plum isolate of Pseudomonas syringae pv. morsprunorum.

PubMed

Smith, A R; Munro, S M; Wait, R; Hignett, R C

1994-07-01

The composition of lipopolysaccharide (LPS) extracted with aqueous phenol from a virulent English plum isolate of Pseudomonas syringae pv. morsprunorum varied according to the partial pressure of oxygen (pO2) in the culture medium at the time of harvest. When pO2 was low, the organism grew slowly and produced smooth LPS bearing rhamnan sidechains. As pO2 was raised, the rate of growth increased and smooth LPS was replaced by a rough species deficient in rhamnose, which co-extracted with a D-glucan. Organization of rhamnose and glucose into separate polymers was shown by the selective susceptibility of the rhamnose-containing polymer to hydrolysis by rhamnanase of the phage A7. By methylation analysis, GC-MS, and 1H- and 13C-NMR spectroscopy, the glucan was shown to consist of alpha (1-->4)-linked residues with alpha (1-->4,6)-branch points and non-reducing terminal residues in the approximate ratio 4:1:1, resembling glycogen in composition. A glucan which co-extracted with LPS using phenol/water from an avirulent plum isolate that was resistant to lysis by phages A1 and A7 was shown by methylation analysis to have a similar structure. Whether the effect on LPS composition was due directly to pO2, or was dependent on the rate of growth, has not been established. It is suggested that, because epiphytic growth would entail exposure to high pO2, English plum isolates growing on the surfaces of host plants might be unable to produce smooth LPS. Since cell surface composition affects virulence in plant-pathogenic pseudomonads, this effect could account for the observed failure of the English plum isolates to enter the host via leaf scars.

Electronic structure and magnetic properties of Ni-doped SnO2 thin films

NASA Astrophysics Data System (ADS)

Sharma, Mayuri; Kumar, Shalendra; Alvi, P. A.

2018-05-01

This paper reports the electronic structure and magnetic properties of Ni-doped SnO2 thin film which were grown on Si (100) substrate by PLD (pulse laser deposition) technique under oxygen partial pressure (PO2). For getting electronic structure and magnetic behavior, the films were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and DC magnetization measurements. The NEXAFS study at Ni L3,2 edge has been done to understand the local environment of Ni and Sn ions within SnO2 lattice. DC magnetization measurement shows that the saturation magnetization increases with the increase in substitution of Ni2+ ions in the system.

Finite-size versus interface-proximity effects in thin-film epitaxial SrTiO3

NASA Astrophysics Data System (ADS)

De Souza, R. A.; Gunkel, F.; Hoffmann-Eifert, S.; Dittmann, R.

2014-06-01

The equilibrium electrical conductivity of epitaxial SrTiO3 (STO) thin films was investigated as a function of temperature, 950≤ T/K ≤1100, and oxygen partial pressure, 10-23≤ pO2/bar ≤1. Compared with single-crystal STO, nanoscale thin-film STO exhibited with decreasing film thickness an increasingly enhanced electronic conductivity under highly reducing conditions, with a corresponding decrease in the activation enthalpy of conduction. This implies substantial modification of STO's point-defect thermodynamics for nanoscale film thicknesses. We argue, however, against such a finite-size effect and for an interface-proximity effect. Indeed, assuming trapping of oxygen vacancies at the STO surface and concomitant depletion of oxygen vacancies—and accumulation of electrons—in an equilibrium surface space-charge layer, we are able to predict quantitatively the conductivity as a function of temperature, oxygen partial pressure, and film thickness. Particularly complex behavior is predicted for ultrathin films that are consumed entirely by space charge.

A method for measuring brain partial pressure of oxygen in unanesthetized unrestrained subjects: the effect of acute and chronic hypoxia on brain tissue PO(2).

PubMed

Ortiz-Prado, E; Natah, Siraj; Srinivasan, Sathyanarayanan; Dunn, Jeff F

2010-11-30

The level of tissue oxygenation provides information related to the balance between oxygen delivery, oxygen utilization, tissue reactivity and morphology during physiological conditions. Tissue partial pressure of oxygen (PtO(2)) is influenced by the use of anesthesia or restraint. These factors may impact the absolute level of PtO(2). In this study we present a novel fiber optic method to measure brain PtO(2). This method can be used in unanesthetized, unrestrained animals, provides absolute values for PO(2), has a stable calibration, does not consume oxygen and is MRI compatible. Brain PtO(2) was studied during acute hypoxia, as well as before and after 28 days of high altitude acclimatization. A sensor was chronically implanted in the frontal cortex of eight Wistar rats. It is comprised of a fiber optic probe with a tip containing material that fluoresces with an oxygen dependent lifetime. Brain PtO(2) declines by 80% and 76% pre- and post-acclimatization, respectively, when the fraction of inspired oxygen declines from 0.21 to 0.08. In addition, a linear relationship between brain PtO(2) and inspired O(2) levels was demonstrated r(2)=0.98 and r(2)=0.99 (pre- and post-acclimatization). Hypoxia acclimatization resulted in an increase in the overall brain PtO(2) by approximately 35%. This paper demonstrates the use of a novel chronically implanted fiber optic based sensor for measuring absolute PtO(2). It shows a very strong linear relationship in awake animals between inspired O(2) and tissue O(2), and shows that there is a proportional increase in PtO(2) over a range of inspired values after exposure to chronic hypoxia. Copyright © 2010 Elsevier B.V. All rights reserved.

Complete healing of chronic wounds of a lower leg with haemoglobin spray and regeneration of an accompanying severe dermatoliposclerosis with intermittent normobaric oxygen inhalation (INBOI): a case report

PubMed Central

Barnikol, Wolfgang K. R.; Pötzschke, Harald

2011-01-01

A new healing procedure has been developed on the basis of the successful treatment of therapy-resistant hypoxic (and practically anoxic) leg ulcerations located within a heavy dermatoliposclerosis. The procedure involves an initial intra-ulceral application of haemoglobin followed by the intermittent administration of normobaric oxygen via inhalation. Haemoglobin is capable of externally supplying the granulating wound bed with oxygen at low partial pressure in a physiological manner, like a micro lung, so that oxidative stress can be avoided. A long-term daily administration of oxygen from within – including the peri-ulceral skin – is achieved by intermittent normobaric oxygen inhalation (INBOI) regularly throughout the day in the form of 1-hour sessions. Using this combined healing treatment during haemoglobin applications the ulcerations healed within about 1 month, and subsequently with INBOI therapy within further approx. 4 months the peri-ulceral skin regenerated as far as the oxygenation status was concerned: The peri-ulceral transcutaneous oxygen partial pressure (tcPO2) of zero (measured during breathing of normal air) rose to a satisfactory value of approx. 35 mmHg. After 28 months of treatment, the completely hypoxic and degenerated skin on the leg had practically returned to normal with a PO2 of 45 mmHg. Furthermore, the skin dermatoliposclerosis regressed. The skin regeneration was long-lasting, which was probably related to cellular tissue regeneration with an increase in the capillary density, whereby it had to be maintained by regular oxygen inhalation (INBOI maintaining treatment). By unintended intra-individual therapy variations it is evidenced that local hypoxia was the reason for skin degeneration: 3 x 1 h oxygen inhalation were sufficient for the healing treatment; 2 x 1 h sufficed for maintenance, whereas 2 x 0.5 h did not. The new procedure carries practically no risks, is simple, cheap and effective. Whereas the application of haemoglobin requires professional supervision, the oxygen inhalation can be carried out at home following initial guidance and monitoring by a physician. Using this novel method, the therapy-resistant ulceration could be closed within 5 months, during which daily outpatient care was only necessary for 1 month. The successful outcome of the treatment in terms of improvement of oxygen supply can monitored at any time using peri-ulceral tcPO2 measurements, whereby, due to the inhomogeneity of the values, measurements at a minimum of two locations at the wound edge are strongly recommended and more measurements at more skin locations would be preferable. Besides its use in the healing of ulcers, the new procedure is also suitable for the prevention of ulceration development (prophylactic INBOI treatment) in skin rendered susceptible due to the presence of hypoxia. Here, peri-ulceral transcutaneous oxygen partial pressures of below 10 mmHg should be considered as being critical and are an indication for a prophylactic oxygen inhalation treatment. The new procedure may also be suitable even before the peri-ulceral oxygen partial pressure falls below 10 mmHg. Four measures for rehabilitation, conservation, and prevention with regard to a healed chronic wound are proposed. PMID:21468328

High-temperature potentiometric oxygen sensor with internal reference

DOEpatents

Routbort, Jules L [Hinsdale, IL; Singh, Dileep [Naperville, IL; Dutta, Prabir K [Worthington, OH; Ramasamy, Ramamoorthy [North Royalton, OH; Spirig, John V [Columbus, OH; Akbar, Sheikh [Hilliard, OH

2011-11-15

A compact oxygen sensor is provided, comprising a mixture of metal and metal oxide an enclosure containing said mixture, said enclosure capable of isolating said mixture from an environment external of said enclosure, and a first wire having a first end residing within the enclosure and having a second end exposed to the environment. Also provided is a method for the fabrication of an oxygen sensor, the method comprising confining a metal-metal oxide solid mixture to a container which consists of a single material permeable to oxygen ions, supplying an electrical conductor having a first end and a second end, whereby the first end resides inside the container as a reference (PO.sub.2).sup.ref, and the second end resides outside the container in the atmosphere where oxygen partial pressure (PO.sub.2).sup.ext is to be measured, and sealing the container with additional single material such that grain boundary sliding occurs between grains of the single material and grains of the additional single material.

The origin of current blocking in interfacial conduction in Sr-doped lanthanum gallates

NASA Astrophysics Data System (ADS)

Park, Hee Jung

2018-02-01

The grain boundary transport of lanthanum gallate has been studied with various doping concentrations, and the origins of blocking on the grain boundary are compared. La1-xSrxGaO3 samples (x = 0.005, 0.01, 0.05 and 0.1) have been prepared and their bulk (grain) and grain boundary resistances been experimentally measured as a function of temperature (T: 200-550 °C) and oxygen partial pressure (Po2) using ac-impedance measurements. In addition, Hebb-Wagner polarization measurements have been conducted to investigate the electrical conductivity of minor charge carriers in the lanthanum gallates. The grain boundary resistance in the low-doped materials (x = 0.005 and 0.01) increases with increasing Po2 while in the highly-doped materials (x = 0.05, 0.1) it hardly depended on Po2. At lower concentrations conduction is mixed and at higher concentrations is found to be predominantly ionic conductivity. The space charge model successfully describes the mixed conduction at the grain boundary at low-doping, but does not explain the predominant ionic conductivity at high-doping. The origin of blocking at high-doping is explained by the crystallographic asymmetry of the grain boundary with respect to the bulk and/or Sr-segregation.

Photoacoustic lifetime imaging for direct in vivo tissue oxygen monitoring

PubMed Central

Shao, Qi; Ashkenazi, Shai

2015-01-01

Abstract. Measuring the partial pressure of oxygen (pO2) in tissue may provide physicians with essential information about the physiological state of tissue. However, currently available methods for measuring or imaging tissue pO2 have significant limitations, preventing them from being widely used in clinics. Recently, we have reported a direct and noninvasive in vivo imaging modality based on the photoacoustic lifetime which overcomes certain drawbacks of the existing methods. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflecting the spatial and temporal distributions of tissue oxygen. Here, we present two studies which apply photoacoustic lifetime imaging (PALI) to monitor changes of tissue oxygen induced by external modulations. The first study modulates tissue oxygen by controlling the percentage of oxygen a normal mouse inhales. We demonstrate that PALI is able to reflect the change in oxygen level with respect to normal, oxygen-rich, and oxygen-poor breathing conditions. The second study involves an acute ischemia model using a thin thread tied around the hindlimb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of tissue pO2 and recovery from hypoxia due to reperfusion were tracked and observed by PALI. PMID:25748857

Effect of wheelchair mass, tire type and tire pressure on physical strain and wheelchair propulsion technique.

PubMed

de Groot, Sonja; Vegter, Riemer J K; van der Woude, Lucas H V

2013-10-01

The purpose of this study was to evaluate the effect of wheelchair mass, solid vs. pneumatic tires and tire pressure on physical strain and wheelchair propulsion technique. 11 Able-bodied participants performed 14 submaximal exercise blocks on a treadmill with a fixed speed (1.11 m/s) within 3 weeks to determine the effect of tire pressure (100%, 75%, 50%, 25% of the recommended value), wheelchair mass (0 kg, 5 kg, or 10 kg extra) and tire type (pneumatic vs. solid). All test conditions (except pneumatic vs. solid) were performed with and without instrumented measurement wheels. Outcome measures were power output (PO), physical strain (heart rate (HR), oxygen uptake (VO2), gross mechanical efficiency (ME)) and propulsion technique (timing, force application). At 25% tire pressure PO and subsequently VO2 were higher compared to 100% tire pressure. Furthermore, a higher tire pressure led to a longer cycle time and contact angle and subsequently lower push frequency. Extra mass did not lead to an increase in PO, physical strain or propulsion technique. Solid tires led to a higher PO and physical strain. The solid tire effect was amplified by increased mass (tire × mass interaction). In contrast to extra mass, tire pressure and tire type have an effect on PO, physical strain or propulsion technique of steady-state wheelchair propulsion. As expected, it is important to optimize tire pressure and tire type. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Effects of low and standard intra-abdominal pressure on systemic inflammation and immune response in laparoscopic adrenalectomy: A prospective randomised study.

PubMed

Schietroma, Mario; Pessia, Beatrice; Stifini, Derna; Lancione, Laura; Carlei, Francesco; Cecilia, Emanuela Marina; Amicucci, Gianfranco

2016-01-01

The advantages of laparoscopic adrenalectomy (LA) over open adrenalectomy are undeniable. Nevertheless, carbon dioxide (CO2) pneumoperitoneum may have an unfavourable effect on the local immune response. The aim of this study was to compare changes in the systemic inflammation and immune response in the early post-operative (p.o.) period after LA performed with standard and low-pressure CO2 pneumoperitoneum. We studied, in a prospective randomised study, 51 patients consecutively with documented adrenal lesion who had undergone a LA: 26 using standard-pressure (12-14 mmHg) and 25 using low-pressure (6-8 mmHg) pneumoperitoneum. White blood cells (WBC), peripheral lymphocyte subpopulation, human leucocyte antigen-DR (HLA-DR), neutrophil elastase, interleukin (IL)-6 and IL-1, and C-reactive protein (CRP) were investigated. Significantly higher concentrations of neutrophil elastase, IL-6 and IL-1 and CRP were detected p.o. in the standard-pressure group of patients in comparison with the low-pressure group (P < 0.05). A statistically significant change in HLA-DR expression was recorded p.o. at 24 h, as a reduction of this antigen expressed on the monocyte surface in patients from the standard group; no changes were noted in low-pressure group patients (P < 0.05). This study demonstrated that reducing the pressure of the pneumoperitoneum to 6-8 mmHg during LA reduced p.o. inflammatory response and averted p.o. immunosuppression.

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model.

PubMed

Bian, Weishuai; Chen, Wei; Chao, Yangong; Wang, Lan; Li, Liming; Guan, Jian; Zang, Xuefeng; Zhen, Jie; Sheng, Bo; Zhu, Xi

2017-04-01

This study aimed to apply the dead space fraction [ratio of dead space to tidal volume (VD/VT)] to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS). Twelve swine models of ARDS were constructed. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H 2 O. The PEEP was reduced by 2 cm H 2 O every 10 min until 0 cm H 2 O was reached, and VD/VT was measured after each decrement step. VD/VT was measured using single-breath analysis of CO 2 , and calculated from arterial CO 2 partial pressure (PaCO 2 ) and mixed expired CO 2 (PeCO 2 ) using the following formula: VD/VT = (PaCO 2 - PeCO 2 )/PaCO 2 . The optimal PEEP was identified by the lowest VD/VT method. Respiration and hemodynamic parameters were recorded during the periods of pre-injury and injury, and at 4 and 2 cm H 2 O below and above the optimal PEEP (Po). The optimal PEEP in this study was found to be 13.25±1.36 cm H 2 O. During the Po period, VD/VT decreased to a lower value (0.44±0.08) compared with that during the injury period (0.68±0.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. These results indicate that minimal VD/VT can be used for PEEP titration in ARDS.

Increased hemoglobin O2 affinity protects during acute hypoxia

PubMed Central

Yalcin, Ozlem

2012-01-01

Acclimatization to hypoxia requires time to complete the adaptation mechanisms that influence oxygen (O2) transport and O2 utilization. Although decreasing hemoglobin (Hb) O2 affinity would favor the release of O2 to the tissues, increasing Hb O2 affinity would augment arterial O2 saturation during hypoxia. This study was designed to test the hypothesis that pharmacologically increasing the Hb O2 affinity will augment O2 transport during severe hypoxia (10 and 5% inspired O2) compared with normal Hb O2 affinity. RBC Hb O2 affinity was increased by infusion of 20 mg/kg of 5-hydroxymethyl-2-furfural (5HMF). Control animals received only the vehicle. The effects of increasing Hb O2 affinity were studied in the hamster window chamber model, in terms of systemic and microvascular hemodynamics and partial pressures of O2 (Po2). Pimonidazole binding to hypoxic areas of mice heart and brain was also studied. 5HMF decreased the Po2 at which the Hb is 50% saturated with O2 by 12.6 mmHg. During 10 and 5% O2 hypoxia, 5HMF increased arterial blood O2 saturation by 35 and 48% from the vehicle group, respectively. During 5% O2 hypoxia, blood pressure and heart rate were 58 and 30% higher for 5HMF compared with the vehicle. In addition, 5HMF preserved microvascular blood flow, whereas blood flow decreased to 40% of baseline in the vehicle group. Consequently, perivascular Po2 was three times higher in the 5HMF group compared with the control group at 5% O2 hypoxia. 5HMF also reduced heart and brain hypoxic areas in mice. Therefore, increased Hb O2 affinity resulted in hemodynamics and oxygenation benefits during severe hypoxia. This acute acclimatization process may have implications in survival during severe environmental hypoxia when logistic constraints prevent chronic acclimatization. PMID:22636677

A New, Noninvasive Method of Measuring Impaired Pulmonary Gas Exchange in Lung Disease: An Outpatient Study.

PubMed

West, John B; Crouch, Daniel R; Fine, Janelle M; Makadia, Dipen; Wang, Daniel L; Prisk, G Kim

2018-02-13

It would be valuable to have a noninvasive method of measuring impaired pulmonary gas exchange in patients with lung disease and thus reduce the need for repeated arterial punctures. This study reports the results of using a new test in a group of outpatients attending a pulmonary clinic. Inspired and expired partial pressure of oxygen (PO 2 ) and Pco 2 are continually measured by small, rapidly responding analyzers. The arterial PO 2 is calculated from the oximeter blood oxygen saturation level and the oxygen dissociation curve. The PO 2 difference between the end-tidal gas and the calculated arterial value is called the oxygen deficit. Studies on 17 patients with a variety of pulmonary diseases are reported. The mean ± SE oxygen deficit was 48.7 ± 3.1 mm Hg. This finding can be contrasted with a mean oxygen deficit of 4.0 ± 0.88 mm Hg in a group of 31 normal subjects who were previously studied (P < .0001). The analysis emphasizes the value of measuring the composition of alveolar gas in determining ventilation-perfusion ratio inequality. This factor is largely ignored in the classic index of impaired pulmonary gas exchange using the ideal alveolar PO 2 to calculate the alveolar-arterial oxygen gradient. The results previously reported in normal subjects and the present studies suggest that this new noninvasive test will be valuable in assessing abnormal gas exchange in the clinical setting. Copyright © 2018 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Effects of altered nitric oxide availability on rat muscle microvascular oxygenation during contractions.

PubMed

Ferreira, L F; Padilla, D J; Williams, J; Hageman, K S; Musch, T I; Poole, D C

2006-03-01

To explore the role of nitric oxide (NO) in controlling microvascular O2 pressure (P(O2)mv) at rest and during contractions (1 Hz). We hypothesized that at the onset of contractions sodium nitroprusside (SNP) would raise P(O2)mv and slow the kinetics of P(O2)mv change whereas l-nitro arginine methyl ester (L-NAME) would decrease P(O2)mv and speed its kinetics. We superfused the spinotrapezius muscle of female Sprague-Dawley rats (n = 7, body mass = 298 +/- 10 g) with SNP (300 microM) and L-NAME (1.5 mm) and measured P(O2)mv (phosphorescence quenching) during contractions. SNP decreased mean arterial pressure (92 +/- 5 mmHg) below that of control (CON, 124 +/- 4 mmHg) and L-NAME (120 +/- 4 mmHg) conditions. SNP did not raise P(O2)mv at rest but it did elevate the P(O2)mv-to-MAP ratio (50% increase, P < 0.05) and slow the kinetics by lengthening the time-delay (TD, 14.0 +/- 5.0 s) and time constant (tau, 24.0 +/- 10.0 s) of the response compared with CON (TD, 8.4 +/- 3.3 s; tau, 16.0 +/- 4.5 s, P < 0.05 vs. SNP). L-NAME decreased P(O2)mv at rest and tended to speed tau (10.1 +/- 3.8 s, P = 0.1), while TD (8.1 +/- 1.0 s) was not significantly different. L-NAME also caused P(O2)mv to fall transiently below steady-state contracting values. These results indicate that NO availability can significantly affect P(O2)mv at rest and during contractions and suggests that P(O2)mv derangements in ageing and chronic disease conditions may potentially result from impairments in NO availability.

Optically based quantification of absolute cerebral metabolic rate of oxygen (CMRO2) with high spatial resolution in rodents

NASA Astrophysics Data System (ADS)

Yaseen, Mohammad A.; Srinivasan, Vivek J.; Sakadžić, Sava; Vinogradov, Sergei A.; Boas, David A.

2010-02-01

Measuring oxygen delivery in brain tissue is important for identifying the pathophysiological changes associated with brain injury and various diseases such as cancer, stroke, and Alzheimer's disease. We have developed a multi-modal imaging system for minimally invasive measurement of cerebral oxygenation and blood flow in small animals with high spatial resolution. The system allows for simultaneous measurement of blood flow using Fourier-domain optical coherence tomography, and oxygen partial pressure (pO2) using either confocal or multiphoton phosphorescence lifetime imaging with exogenous porphyrin-based dyes sensitive to dissolved oxygen. Here we present the changes in pO2 and blood flow in superficial cortical vessels of Sprague Dawley rats in response to conditions such as hypoxia, hyperoxia, and functional stimulation. pO2 measurements display considerable heterogeneity over distances that cannot be resolved with more widely used oxygen-monitoring techniques such as BOLD-fMRI. Large increases in blood flow are observed in response to functional stimulation and hypoxia. Our system allows for quantification of cerebral metabolic rate of oxygen (CMRO2) with high spatial resolution, providing a better understanding of metabolic dynamics during functional stimulation and under various neuropathologies. Ultimately, better insight into the underlying mechanisms of neuropathologies will facilitate the development of improved therapeutic strategies to minimize damage to brain tissue.

Circulatory oxygen transport in the water flea Daphnia magna.

PubMed

Bäumer, C; Pirow, R; Paul, R J

2002-05-01

To determine the contribution of circulatory convection to tissue oxygen supply in animals of Daphnia magna, heart rate ( f(H)), in-vivo Hb oxygen-saturation ( S(Hb)) and NADH fluorescence intensity ( I(NADH)) as a measure of the tissue oxygenation state were simultaneously measured using digital motion analysis, microabsorption spectroscopy and fluorescence microscopy. In addition, the relationship between stroke volume and body size was established. Groups of differently sized animals (small: 1.4-1.6 mm, medium: 2.7-2.9 mm, large: 3.3 mm) with either low (Hb-poor) or high Hb concentration (Hb-rich) in the hemolymph were exposed to a gradual decrease in ambient oxygen partial pressure ( P(O2amb)) between normoxia and anoxia. In all groups, f(H) increased in response to progressive hypoxia. The hypoxic maximum in f(H) was highest in medium-sized Hb-poor animals, whereas perfusion rate increased continuously with increasing body size in Hb-poor and Hb-rich animals. The P(O2amb) at which Hb in the heart region was half-saturated (in-vivo P(50)) was higher in medium-sized (Hb-poor: 3.2 kPa, Hb-rich: 2.0 kPa) than in small (Hb-poor: 2.1 kPa, Hb-rich: 1.5 kPa) and large animals (Hb-poor: 1.9 kPa). The in-vivo P(50) was always lower in Hb-rich than in Hb-poor animals. The I(NADH) indicated an impairment of tissue oxygenation starting at higher critical P(O2amb) with increasing body size and with lower Hb concentration. Model calculations suggest that at the respective critical P(O2amb), circulatory convection delivers less than half of the oxygen demand in Hb-poor animals. In contrast, in Hb-rich animals, the contribution of circulatory convection to tissue oxygen supply at respective critical P(O2amb) was much greater due to the higher concentration of Hb.

Analytical and pre-analytical performance characteristics of a novel cartridge-type blood gas analyzer for point-of-care and laboratory testing.

PubMed

Oyaert, Matthijs; Van Maerken, Tom; Bridts, Silke; Van Loon, Silvi; Laverge, Heleen; Stove, Veronique

2018-03-01

Point-of-care blood gas test results may benefit therapeutic decision making by their immediate impact on patient care. We evaluated the (pre-)analytical performance of a novel cartridge-type blood gas analyzer, the GEM Premier 5000 (Werfen), for the determination of pH, partial carbon dioxide pressure (pCO 2 ), partial oxygen pressure (pO 2 ), sodium (Na + ), potassium (K + ), chloride (Cl - ), ionized calcium ( i Ca 2+ ), glucose, lactate, and total hemoglobin (tHb). Total imprecision was estimated according to the CLSI EP5-A2 protocol. The estimated total error was calculated based on the mean of the range claimed by the manufacturer. Based on the CLSI EP9-A2 evaluation protocol, a method comparison with the Siemens RapidPoint 500 and Abbott i-STAT CG8+ was performed. Obtained data were compared against preset quality specifications. Interference of potential pre-analytical confounders on co-oximetry and electrolyte concentrations were studied. The analytical performance was acceptable for all parameters tested. Method comparison demonstrated good agreement to the RapidPoint 500 and i-STAT CG8+, except for some parameters (RapidPoint 500: pCO 2 , K + , lactate and tHb; i-STAT CG8+: pO 2 , Na + , i Ca 2+ and tHb) for which significant differences between analyzers were recorded. No interference of lipemia or methylene blue on CO-oximetry results was found. On the contrary, significant interference for benzalkonium and hemolysis on electrolyte measurements were found, for which the user is notified by an interferent specific flag. Identification of sample errors from pre-analytical sources, such as interferences and automatic corrective actions, along with the analytical performance, ease of use and low maintenance time of the instrument, makes the evaluated instrument a suitable blood gas analyzer for both POCT and laboratory use. Copyright © 2018 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

The role of silver in the processing and properties of Bi-2212

NASA Technical Reports Server (NTRS)

Lang, TH.; Heeb, B.; Buhl, D.; Gauckler, L. J.

1995-01-01

The influence of the silver content and the oxygen partial pressure on the solidus temperature and the weight loss during melting of Bi2Sr2Ca1Cu2O(x) has been examined by means of DTA and TGA. By decreasing the oxygen partial pressure the solidus is lowered (e.g. del T = 59 C by decreasing pO2 from 1 atm to 0.001 atm) and the weight loss is increased. The addition of silver causes two effects: (1) the solidus is further decreased (e.g. 2 wt% Ag lower T (solidus) by up to 25 C, depending on the oxygen partial pressure); and (2) the weight loss during melting is reduced. Thick films (10-20 micron in thickness) with 0 and 5 wt% silver and bulk samples with) and 2.7 wt% silver were melt processed in flowing oxygen on a silver substrate in the DTA, allowing the observation of the melting process and a good temperature control. The critical current densities are vigorously dependent on the maximum processing temperature. The highest j(sub c) in thick films (8000 A/sq cm at 77 K, O T) was reached by melting 7 C above the solidus temperature. The silver addition shows no significant effect on the processing parameters or the superconducting properties. The highest j(sub c) for bulk samples (1 mm in thickness) was obtained by partial melting at 900 C or 880 C, depending on the silver content of the powder (0 or 2.7 wt%). The j(sub c) of the samples is slightly enhanced from 1800 A/sq cm (at 77 K, O T) to 2000 A/sq cm by the silver addition. To be able to reach at least 80% of the maximum critical current density, the temperature has to be controlled in a window of 5 C for thick films and 17 C for bulk samples.

Preflight studies on tolerance of pocket mice to oxygen and heat. I - Physiological studies

NASA Technical Reports Server (NTRS)

Leon, H. A.; Suri, K.; Mctigue, M.; Smith, J.; Cooper, W.; Miquel, J.; Ashley, W. W.; Behnke, A. R., Jr.; Saunders, J. F.

1975-01-01

Tests were carried out on pocket mice to ascertain their tolerance to elevated oxygen pressures alone and to a combination of hyperoxia and heat in excess of that expected during the flight of the mice on Apollo XVII. The mice withstood oxygen partial pressures up to 12 psi at normal room temperature (24 C, 75 F) over a period of 7 days. A few mice previously exposed to increased PO2 died in the course of exposure to an oxygen pressure of 10 psi or 12 psi (517 mm or 620 mm Hg) for 13 d in ambient heat of 32 C (90 F). Supplemental vitamin E and physiological saline loading given prior to exposure had no apparent protective effect. The overall conclusion was that the pocket mice which were to go on Apollo XVII could readily survive the ambient atmosphere to which they would be exposed.

64Cu-ATSM Reflects pO2 Levels in Human Head and Neck Cancer Xenografts but Not in Colorectal Cancer Xenografts: Comparison with 64CuCl2.

PubMed

Li, Fan; Jørgensen, Jesper T; Forman, Julie; Hansen, Anders E; Kjaer, Andreas

2016-03-01

The hypoxia PET tracer (64)Cu-diacetyl-bis(N(4)-methylthiosemicarbazonate) ((64)Cu-ATSM) has shown promising results in clinical studies. However, concerns have been raised with regard to the possible effect of copper metabolism and free copper on tumor uptake and thereby the robustness of (64)Cu-ATSM as a hypoxia marker. In this study, accumulation and distribution of (64)Cu-ATSM and (64)CuCl2 in tumor tissue were compared with partial pressure of oxygen (pO2) probe measurements. One-hour dynamic PET scans were performed on nude mice bearing subcutaneous human head and neck tumors (FaDu) and human colorectal tumors (HT29) after administration of either (64)Cu-ATSM or (64)CuCl2. Subsequently, tracks were generated and track markers were positioned in tumors to allow for registration of their exact location on the high-resolution CT scan. After completion of the CT scan, pO2 probe measurements were performed along each track. PET and CT images were coregistered and ROIs drawn on the basis of the location of track markers and pO2 probe measurement depth. A linear mixed model for repeated measures was applied for the comparison of PET tracer uptake to corresponding pO2 values. Comparable uptake of (64)Cu-ATSM and (64)CuCl2 was found in the kidney, muscle, and liver of all animals, but (64)CuCl2 showed a higher uptake 10-60 min after injection in both tumor models. Significant differences were also found for both tumor-to-muscle and tumor-to-liver ratios. The intratumoral distribution of (64)Cu-ATSM, but not (64)CuCl2, showed a significant negative relationship with pO2 measurements in FaDu tumors. However, this relationship was not found in HT29 tumors. (64)Cu-ATSM and (64)CuCl2 displayed different uptake in tumors. In human head and neck xenografts, (64)Cu-ATSM but not (64)CuCl2 reflected pO2 measurements, indicating that (64)Cu-ATSM is a hypoxia-specific marker in this tumor type. However, data from colorectal cancer xenografts indicated that (64)Cu-ATSM may not be a hypoxia marker in all tumor types. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Basic arterial blood gas biomarkers as a predictor of mortality in tetralogy of Fallot patients.

PubMed

Bhardwaj, Vandana; Kapoor, Poonam Malhotra; Irpachi, Kalpana; Ladha, Suruchi; Chowdhury, Ujjwal Kumar

2017-01-01

Serum lactate and base deficit have been shown to be a predictor of morbidity and mortality in critically ill patients. Poor preoperative oxygenation appears to be one of the significant factors that affects early mortality in tetralogy of Fallot (TOF). There is little published literature evaluating the utility of serum lactate, base excess (BE), and oxygen partial pressure (PO 2 ) as simple, widely available, prognostic markers in patients undergoing surgical repair of TOF. This prospective, observational study was conducted in 150 TOF patients, undergoing elective intracardiac repair. PO 2 , BE, and lactate levels at three different time intervals were recorded. Arterial blood samples were collected after induction (T1), after cardiopulmonary bypass (T2), and 48 h (T3) after surgery in the Intensive Care Unit (ICU). To observe the changes in PO 2 , BE, and lactate levels over a period of time, repeated measures analysis was performed with Bonferroni method. The receiver operating characteristics (ROC) analysis was used to find area under curve (AUC) and cutoff values of various biomarkers for predicting mortality in ICU. The patients who could not survive showed significant elevated lactate levels at baseline (T1) and postoperatively (T2) as compared to patients who survived after surgery (P < 0.001). However, in nonsurvivors, the BE value decreased significantly in the postoperative period in comparison to survivors (-2.8 ± 4.27 vs. 5.04 ± 2.06) (P < 0.001). In nonsurvivors, there was a significant fall of PO 2 to a mean value of 59.86 ± 15.09 in ICU (T3), whereas those who survived had a PO 2 of 125.86 ± 95.09 (P < 0.001). The ROC curve analysis showed that lactate levels (T3) have highest mortality predictive value (AUC: 96.9%) as compared to BE (AUC: 94.5%) and PO 2 (AUC: 81.1%). Serum lactate and BE may be used as prognostic markers to predict mortality in patients undergoing TOF repair. The routine analysis of these simple, fast, widely available, and cost-effective biomarkers should be encouraged to predict prognosis of TOF patients.

Synthetic lead bromapatite: X-ray structure at ambient pressure and compressibility up to about 20 GPa

NASA Astrophysics Data System (ADS)

Liu, Xi; Fleet, Michael E.; Shieh, Sean R.; He, Qiang

2011-05-01

Lead bromapatite [Pb10(PO4)6Br2] has been synthesized via solid-state reaction at pressures up to 1.0 GPa, and its structure determined by single-crystal X-ray diffraction at ambient temperature and pressure. The large bromide anion is accommodated in the c-axis channel by lateral displacements of structural elements, particularly of Pb2 cations and PO4 tetrahedra. The compressibility of bromapatite was also investigated up to about 20.7 GPa at ambient temperature, using a diamond-anvil cell and synchrotron X-ray radiation. The compressibility of lead bromapatite is significantly different from that of lead fluorapatite. The pressure-volume data of lead bromapatite ( P < 10 GPa) fitted to the third-order Birch-Murnaghan equation yield an isothermal bulk modulus ( K T ) of 49.8(16) GPa and first pressure derivative ( KT^' } ) of 10.1(10). If KT^' } is fixed at 4, the derived K T is 60.8(11) GPa. The relative difference of the bulk moduli of these two lead apatites is thus about 12%, which is about two times the relative difference of the bulk moduli (~5%) of the calcium apatites fluorapatite [Ca10(PO4)6F2], chlorapatite [Ca10(PO4)6Cl2] and hydroxylapatite [Ca10(PO4)6(OH)2]. Another interesting feature apparently related to the replacement of F by Br in lead apatite is the switch in the principle axes of the strain ellipsoid: the c-axis is less compressible than the a-axis in lead bromapatite but more compressible in lead fluorapatite.

High-pressure structural and vibrational properties of monazite-type BiPO4, LaPO4, CePO4, and PrPO4

NASA Astrophysics Data System (ADS)

Errandonea, D.; Gomis, O.; Rodríguez-Hernández, P.; Muñoz, A.; Ruiz-Fuertes, J.; Gupta, M.; Achary, S. N.; Hirsch, A.; Manjon, F. J.; Peters, L.; Roth, G.; Tyagi, A. K.; Bettinelli, M.

2018-02-01

Monazite-type BiPO4, LaPO4, CePO4, and PrPO4 have been studied under high pressure by ab initio simulations and Raman spectroscopy measurements in the pressure range of stability of the monazite structure. A good agreement between experimental and theoretical Raman-active mode frequencies and pressure coefficients has been found which has allowed us to discuss the nature of the Raman-active modes. Besides, calculations have provided us with information on how the crystal structure is modified by pressure. This information has allowed us to determine the equation of state and the isothermal compressibility tensor of the four studied compounds. In addition, the information obtained on the polyhedral compressibility has been used to explain the anisotropic axial compressibility and the bulk compressibility of monazite phosphates. Finally, we have carried out a systematic discussion on the high-pressure behavior of the four studied phosphates in comparison to results of previous studies.

High pressure structural investigation on alluaudites Na{sub 2}Fe{sub 3}(PO{sub 4}){sub 3}-Na{sub 2}FeMn{sub 2}(PO{sub 4}){sub 3} system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Jing; Huang, Weifeng; Qin, Shan

Alluaudites are promising electrochemical materials benefited from the open structure. Structural variations of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) system have been studied by synchrotron radiation X-ray diffraction combined with diamond anvil cell technique up to ~10 GPa at room temperature. No phase transition is observed. The excellent structural stability is mainly due to the flexible framework plus strong covalent P-O bond. Mn{sup 2+} instead of Fe can be described as Na{sup +}+2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy. The replacement of Fe with larger Mn{sup 2+} is equivalentmore » to applying negative chemical pressure to the material. And it causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe. External pressure effect produces anisotropic lattice shrinkage. Structural considerations related to these variations and promising application prospects are discussed. - Graphical abstract: Figure 1 The crystal structure of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) projected along the c-axis. Alluaudites adopt a flexible framework plus strong covalent P-O bond, which contribute to excellent structural stability up to ~10 GPa. Mn{sup 2+} instead of Fe can be described as Na{sup ++}2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy, and it is equivalent to applying negative chemical pressure to the host. The substitution causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe.« less

Measurements of pulmonary gas exchange efficiency using expired gas and oximetry: results in normal subjects.

PubMed

West, John B; Wang, Daniel L; Prisk, G Kim

2018-04-01

We are developing a novel, noninvasive method for measuring the efficiency of pulmonary gas exchange in patients with lung disease. The patient wears an oximeter, and we measure the partial pressures of oxygen and carbon dioxide in inspired and expired gas using miniature analyzers. The arterial Po 2 is then calculated from the oximeter reading and the oxygen dissociation curve, using the end-tidal Pco 2 to allow for the Bohr effect. This calculation is only accurate when the oxygen saturation is <94%, and therefore, these normal subjects breathed 12.5% oxygen. When the procedure is used in patients with hypoxemia, they breathe air. The Po 2 difference between the end-tidal and arterial values is called the "oxygen deficit." Preliminary data show that this index increases substantially in patients with lung disease. Here we report measurements of the oxygen deficit in 20 young normal subjects (age 19 to 31 yr) and 11 older normal subjects (47 to 88 yr). The mean value of the oxygen deficit in the young subjects was 2.02 ± 3.56 mmHg (means ± SD). This mean is remarkably small. The corresponding value in the older group was 7.53 ± 5.16 mmHg (means ± SD). The results are consistent with the age-related trend of the traditional alveolar-arterial difference, which is calculated from the calculated ideal alveolar Po 2 minus the measured arterial Po 2 . That measurement requires an arterial blood sample. The present study suggests that this noninvasive procedure will be valuable in assessing the degree of impaired gas exchange in patients with lung disease.

Image-based 3D modeling study of the influence of vessel density and blood hemoglobin concentration on tumor oxygenation and response to irradiation.

PubMed

Lagerlöf, Jakob H; Kindblom, Jon; Cortez, Eliane; Pietras, Kristian; Bernhardt, Peter

2013-02-01

Hypoxia is one of the most important factors influencing clinical outcome after radiotherapy. Improved knowledge of factors affecting the levels and distribution of oxygen within a tumor is needed. The authors constructed a theoretical 3D model based on histological images to analyze the influence of vessel density and hemoglobin (Hb) concentration on the response to irradiation. The pancreases of a Rip-Tag2 mouse, a model of malignant insulinoma, were excised, cryosectioned, immunostained, and photographed. Vessels were identified by image thresholding and a 3D vessel matrix assembled. The matrix was reduced to functional vessel segments and enlarged by replication. The steady-state oxygen tension field of the tumor was calculated by iteratively employing Green's function method for diffusion and the Michaelis-Menten model for consumption. The impact of vessel density on the radiation response was studied by removing a number of randomly selected vessels. The impact of Hb concentration was studied by independently changing vessel oxygen partial pressure (pO(2)). For each oxygen distribution, the oxygen enhancement ratio (OER) was calculated and the mean absorbed dose at which the tumor control probability (TCP) was 0.99 (D(99)) was determined using the linear-quadratic cell survival model (LQ model). Decreased pO(2) shifted the oxygen distribution to lower values, whereas decreased vessel density caused the distribution to widen and shift to lower values. Combined scenarios caused lower-shifted distributions, emphasising log-normal characteristics. Vessel reduction combined with increased blood pO(2) caused the distribution to widen due to a lack of vessels. The most pronounced radiation effect of increased pO(2) occurred with tumor tissue with 50% of the maximum vessel density used in the simulations. A 51% decrease in D(99), from 123 to 60 Gy, was found between the lowest and highest pO(2) concentrations. Our results indicate that an intermediate vascular density region exists where enhanced blood oxygen concentration may be beneficial for radiation response. The results also suggest that it is possible to distinguish between diffusion-limited and anemic hypoxia from the characteristics of the pO(2) distribution.

A DTI Study to Probe Tumor Microstructure And Its Connection With Hypoxia

PubMed Central

Majumdar, Shreyan; Triplett, William; Epel, Boris; Halpern, Howard

2015-01-01

Solid tumors have chaotic organization of blood vessels, disruptive nerve paths and muscle fibers that result in a hostile and heterogeneous microenvironment. These tumor regions are often hypoxic and resistant to radiation therapy. The knowledge of partial pressure of oxygen concentration (pO2), in conjunction with the information about tissue organization, can predict tissue health and may eventually be used in combination with intensity-modulated radiation therapy (IMRT) for targeted destruction of radiation-resistant areas, while sparing healthy tissues. Diffusion tensor imaging (DTI) based parameter fractional anisotropy (FA) can be used to assess organization of tissue microstructure, whereas the pO2 can be measured using electron paramagnetic resonance oxygen imaging (EPROI). This study is our first step to connect these two important physiological parameters. We calculated FA in fixed fibrosarcoma (FSa) grown in hind leg of nude mice (n = 6) using preclinical 9.4 T MRI. The FA in tumor region (0.34 ± 0.014) was found to be lower when compared to normal surrounding region (0.36 ± 0.013). We hypothesized that the change in FA is directly correlated with the change in oxygen concentration in tumor. We present preliminary in vivo results showing a positive correlation (R = 0.85, p = 0.017) between the FA and pO2 values acquired for MCa4 tumor (n = 1) using DTI and EPROI. PMID:25570064

A DTI study to probe tumor microstructure and its connection with hypoxia.

PubMed

Majumdar, Shreyan; Kotecha, Mrignayani; Triplett, William; Epel, Boris; Halpern, Howard

2014-01-01

Solid tumors have chaotic organization of blood vessels, disruptive nerve paths and muscle fibers that result in a hostile and heterogeneous microenvironment. These tumor regions are often hypoxic and resistant to radiation therapy. The knowledge of partial pressure of oxygen concentration (pO2), in conjunction with the information about tissue organization, can predict tissue health and may eventually be used in combination with intensity-modulated radiation therapy (IMRT) for targeted destruction of radiation-resistant areas, while sparing healthy tissues. Diffusion tensor imaging (DTI) based parameter fractional anisotropy (FA) can be used to assess organization of tissue microstructure, whereas the pO2 can be measured using electron paramagnetic resonance oxygen imaging (EPROI). This study is our first step to connect these two important physiological parameters. We calculated FA in fixed fibrosarcoma (FSa) grown in hind leg of nude mice (n = 6) using preclinical 9.4 T MRI. The FA in tumor region (0.34 ± 0.014) was found to be lower when compared to normal surrounding region (0.36 ± 0.013). We hypothesized that the change in FA is directly correlated with the change in oxygen concentration in tumor. We present preliminary in vivo results showing a positive correlation (R = 0.85, p = 0.017) between the FA and pO2 values acquired for MCa4 tumor (n = 1) using DTI and EPROI.

On the time behaviour of the concentration of pyrazinium radical cations in the early stage of the Maillard reaction

NASA Astrophysics Data System (ADS)

Stoesser, Reinhard; Klein, Jeannette; Peschke, Simone; Zehl, Andrea; Cämmerer, Bettina; Kroh, Lothar W.

2007-08-01

During the early stage of the Maillard reaction pyrazinium radical cations were detected by ESR within the reaction system D-glucose/glycine. The spectra were characterized by completely resolved hyperfine structure. The partial pressure of oxygen and the radical concentrations were measured directly in the reaction mixture by ESR using solutions of the spin probe TEMPOL and of DPPH, respectively. There are quantitative and qualitative relations of the actual concentration of the radical ions to the partial pressure of oxygen, the temperature-time regime and the mechanical mixing of the reaction system. These macroscopic parameters significantly affect both the induction period and the velocity of the time-dependent formation of free radicals. From in situ variations of p(O 2) and p(Ar) including the connected mixing effects caused by the passing the gases through the reaction mixture, steric and chemical effects of the stabilization of the radical ions were established. The determination of suitable and relevant conditions for stabilization and subsequent radical reactions contributes to the elucidation of the macroscopically known antioxidant activity of Maillard products.

Role of nitric oxide of the median preoptic nucleus (MnPO) in the alterations of salivary flow, arterial pressure and heart rate induced by injection of pilocarpine into the MnPO and intraperitoneally.

PubMed

Saad, Wilson A; Guarda, I F M S; Camargo, L A A; Santos, T A F B; Guarda, R S; Saad, Willian A; Simões, S; Rodrigues, J Antunes

2003-07-01

We investigated the effect of L-NAME, a nitric oxide (NO) inhibitor and sodium nitroprusside (SNP), an NO-donating agent, on pilocarpine-induced alterations in salivary flow, mean arterial blood pressure (MAP) and heart rate (HR) in rats. Male Holtzman rats (250-300 g) were implanted with a stainless steel cannula directly into the median preoptic nucleus (MnPO). Pilocarpine (10, 20, 40, 80, 160 g) injected into the MnPO induced an increase in salivary secretion (P<0.01). Pilocarpine (1, 2, 4, 8, 16 mg/kg) ip also increased salivary secretion (P<0.01). Injection of L-NAME (40 g) into the MnPO prior to pilocarpine (10, 20, 40, 80, 160 g) injected into the MnPO or ip (1, 2, 4, 8, 16 mg/kg) increased salivary secretion (P<0.01). SNP (30 g) injected into the MnPO or ip prior to pilocarpine attenuated salivary secretion (P<0.01). Pilocarpine (40 g) injection into the MnPO increased MAP and decreased HR (P<0.01). Pilocarpine (4 mg/kg body weight) ip produced a decrease in MAP and an increase in HR (P<0.01). Injection of L-NAME (40 g) into the MnPO prior to pilocarpine potentiated the increase in MAP and reduced HR (P<0.01). SNP (30 g) injected into the MnPO prior to pilocarpine attenuated (100%) the effect of pilocarpine on MAP, with no effect on HR. Administration of L-NAME (40 g) into the MnPO potentiated the effect of pilocarpine injected ip. SNP (30 g) injected into the MnPO attenuated the effect of ip pilocarpine on MAP and HR. The present study suggests that in the rat MnPO 1) NO is important for the effects of pilocarpine on salivary flow, and 2) pilocarpine interferes with blood pressure and HR (side effects of pilocarpine), that is attenuated by NO.

A Stirred Microchamber for Oxygen Consumption Rate Measurements With Pancreatic Islets

PubMed Central

Papas, Klearchos K.; Pisania, Anna; Wu, Haiyan; Weir, Gordon C.; Colton, Clark K.

2010-01-01

Improvements in pancreatic islet transplantation for treatment of diabetes are hindered by the absence of meaningful islet quality assessment methods. Oxygen consumption rate (OCR) has previously been used to assess the quality of organs and primary tissue for transplantation. In this study, we describe and characterize a stirred microchamber for measuring OCR with small quantities of islets. The device has a titanium body with a chamber volume of about 200 µL and is magnetically stirred and water jacketed for temperature control. Oxygen partial pressure (pO2) is measured by fluorescence quenching with a fiber optic probe, and OCR is determined from the linear decrease of pO2 with time. We demonstrate that measurements can be made rapidly and with high precision. Measurements with βTC3 cells and islets show that OCR is directly proportional to the number of viable cells in mixtures of live and dead cells and correlate linearly with membrane integrity measurements made with cells that have been cultured for 24 h under various stressful conditions. PMID:17497731

Thermophysical Properties Measurement of High-Temperature Liquids Under Microgravity Conditions in Controlled Atmospheric Conditions

NASA Technical Reports Server (NTRS)

Watanabe, Masahito; Ozawa, Shumpei; Mizuno, Akotoshi; Hibiya, Taketoshi; Kawauchi, Hiroya; Murai, Kentaro; Takahashi, Suguru

2012-01-01

Microgravity conditions have advantages of measurement of surface tension and viscosity of metallic liquids by the oscillating drop method with an electromagnetic levitation (EML) device. Thus, we are preparing the experiments of thermophysical properties measurements using the Materials-Science Laboratories ElectroMagnetic-Levitator (MSL-EML) facilities in the international Space station (ISS). Recently, it has been identified that dependence of surface tension on oxygen partial pressure (Po2) must be considered for industrial application of surface tension values. Effect of Po2 on surface tension would apparently change viscosity from the damping oscillation model. Therefore, surface tension and viscosity must be measured simultaneously in the same atmospheric conditions. Moreover, effect of the electromagnetic force (EMF) on the surface oscillations must be clarified to obtain the ideal surface oscillation because the EMF works as the external force on the oscillating liquid droplets, so extensive EMF makes apparently the viscosity values large. In our group, using the parabolic flight levitation experimental facilities (PFLEX) the effect of Po2 and external EMF on surface oscillation of levitated liquid droplets was systematically investigated for the precise measurements of surface tension and viscosity of high temperature liquids for future ISS experiments. We performed the observation of surface oscillations of levitated liquid alloys using PFLEX on board flight experiments by Gulfstream II (G-II) airplane operated by DAS. These observations were performed under the controlled Po2 and also under the suitable EMF conditions. In these experiments, we obtained the density, the viscosity and the surface tension values of liquid Cu. From these results, we discuss about as same as reported data, and also obtained the difference of surface oscillations with the change of the EMF conditions.

Hyperpolarized 129Xe MRI: A Viable Functional Lung Imaging Modality?

PubMed Central

Patz, Samuel; Hersman, F. William; Muradian, Iga; Hrovat, Mirko I.; Ruset, Iulian C.; Ketel, Stephen; Jacobson, Francine; Topulos, George P.; Hatabu, Hiroto; Butler, James P.

2008-01-01

The majority of researchers investigating hyperpolarized gas MRI as a candidate functional lung imaging modality have used 3He as their imaging agent of choice rather than 129Xe. This preference has been predominantly due to, 3He providing stronger signals due to higher levels of polarization and higher gyromagnetic ratio, as well as its being easily available to more researchers due to availability of polarizers (USA) or ease of gas transport (Europe). Most researchers agree, however, that hyperpolarized 129Xe will ultimately emerge as the imaging agent of choice due to its unlimited supply in nature and its falling cost. Our recent polarizer technology delivers vast improvements in hyperpolarized 129Xe output. Using this polarizer, we have demonstrated the unique property of xenon to measure alveolar surface area noninvasively. In this article, we describe our human protocols and their safety, and our results for the measurement of the partial pressure of pulmonary oxygen (pO2) by observation of 129Xe signal decay. We note that the measurement of pO2 by observation of 129Xe signal decay is more complex than that for 3He because of an additional signal loss mechanism due to interphase diffusion of 129Xe from alveolar gas spaces to septal tissue. This results in measurements of an equivalent pO2 that accounts for both traditional T1 decay from pO2 and that from interphase diffusion. We also provide an update on new technological advancements that form the foundation for an improved compact design polarizer as well as improvements that provide another order-of-magnitude scale-up in xenon polarizer output. PMID:17890035

Tannins from Potentilla officinalis display antiinflammatory effects in the UV erythema test and on atopic skin.

PubMed

Hoffmann, Julia; Wölfle, Ute; Schempp, Christoph M; Casetti, Federica

2016-09-01

Rich in tannins, the rhizome of Potentilla officinalis (PO) has traditionally been used in the topical treatment of inflammatory disorders of the skin and mucous membranes. The objective of the present study was to examine the antiinflammatory effects of PO in the UV erythema test as well as in patients with atopic skin. Using the UV erythema test, the antiinflammatory effects of a PO extract (2 %) - compared to 1 % hydrocortisone acetate - were assessed in a randomized, prospective, placebo-controlled double-blind study of 40 healthy volunteers. In the context of a prospective non-controlled trial, the efficacy and tolerability of 2 % PO cream (applied to defined test areas twice daily for two weeks) was evaluated in twelve adults and twelve children with atopic skin using a partial SCORAD. In addition, the effects on the degree of erythema in the test areas was measured photometrically. In the UV erythema test, PO cream significantly reduced the erythema index compared to the vehicle. The antiinflammatory effects of PO cream were comparable to those of 1 % hydrocortisone acetate cream. The clinical study with atopic patients revealed a significant reduction in the partial SCORAD as well as erythema in the test areas. No adverse events were recorded. PO cream displays antiinflammatory effects in vivo. It is effective in and well tolerated by patients with atopic skin. © 2016 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

Hypoxia Tolerance and Metabolic Suppression in Oxygen Minimum Zone Euphausiids: Implications for Ocean Deoxygenation and Biogeochemical Cycles.

PubMed

Seibel, Brad A; Schneider, Jillian L; Kaartvedt, Stein; Wishner, Karen F; Daly, Kendra L

2016-10-01

The effects of regional variations in oxygen and temperature levels with depth were assessed for the metabolism and hypoxia tolerance of dominant euphausiid species. The physiological strategies employed by these species facilitate prediction of changing vertical distributions with expanding oxygen minimum zones and inform estimates of the contribution of vertically migrating species to biogeochemical cycles. The migrating species from the Eastern Tropical Pacific (ETP), Euphausia eximia and Nematoscelis gracilis, tolerate a Partial Pressure (PO2) of 0.8 kPa at 10 °C (∼15 µM O2) for at least 12 h without mortality, while the California Current species, Nematoscelis difficilis, is incapable of surviving even 2.4 kPa PO2 (∼32 µM O2) for more than 3 h at that temperature. Euphausia diomedeae from the Red Sea migrates into an intermediate oxygen minimum zone, but one in which the temperature at depth remains near 22 °C. Euphausia diomedeae survived 1.6 kPa PO2 (∼22 µM O2) at 22 °C for the duration of six hour respiration experiments. Critical oxygen partial pressures were estimated for each species, and, for E. eximia, measured via oxygen consumption (2.1 kPa, 10 °C, n = 2) and lactate accumulation (1.1 kPa, 10 °C). A primary mechanism facilitating low oxygen tolerance is an ability to dramatically reduce energy expenditure during daytime forays into low oxygen waters. The ETP and Red Sea species reduced aerobic metabolism by more than 50% during exposure to hypoxia. Anaerobic glycolytic energy production, as indicated by whole-animal lactate accumulation, contributed only modestly to the energy deficit. Thus, the total metabolic rate was suppressed by ∼49-64%. Metabolic suppression during diel migrations to depth reduces the metabolic contribution of these species to vertical carbon and nitrogen flux (i.e., the biological pump) by an equivalent amount. Growing evidence suggests that metabolic suppression is a widespread strategy among migrating zooplankton in oxygen minimum zones and may have important implications for the economy and ecology of the oceans. The interacting effects of oxygen and temperature on the metabolism of oceanic species facilitate predictions of changing vertical distribution with climate change. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Adaptive Algorithm for Aircraft Configuration in Turbulent Flow

DTIC Science & Technology

1992-11-25

8217), + a2 (APO) (bUo)),2 + r4 (1 - APO) (bUO), (27) AP is the pressure switch chat is used to turn the shock smoothing and the background smoothing on at...the appropriate regions. For any node 0, the pressure switch is computed as (APo)= E𔃻=1 (PN()- PO) (28) zF:,’ + PO) the summation is over all the edges...that share the node 0. The pressure switch is normalized by the maximum value over the domain so that 0 < AP < 1. When evaluated as above, AP has a

Transcutaneous oxygen pressure measurement in diabetic foot ulcers: mean values and cut-point for wound healing.

PubMed

Yang, Chuan; Weng, Huan; Chen, Lihong; Yang, Haiyun; Luo, Guangming; Mai, Lifang; Jin, Guoshu; Yan, Li

2013-01-01

The purpose of this study was to investigate mean values and cut-point of transcutaneous oxygen pressure (TcPO2) measurement in patients with diabetic foot ulcers. Prospective, descriptive study. Sixty-one patients with diabetes mellitus and foot ulcers comprised the sample. The research setting was Sun Yat-sen Memorial Hospital of SunYat-sen University, Guangzhou, China. Participants underwent transcutaneous oxygen (TcPO2) measurement at the dorsum of foot. Patients were classified into 3 groups according to clinical outcomes: (1) ulcers healed with intact skin group, (2) ulcer improved, and (3) ulcer failed to improve. TcPO2 was assessed and cut-points for predicting diabetic foot ulcer healing were calculated. Thirty-six patients healed with intact skin, 8 experienced improvement, and 17 showed no improvement. Mean TcPO2 levels were significantly higher (P< .001) in healed ulcers with intact skin (32 ± 10 mmHg) when compared to the improvement group (30 ± 7 mmHg) and the nonhealing group (15 ± 12 mmHg). All patients with TcPO2≤ 10 mmHg failed to heal or experienced deterioration in their foot ulcers. In contrast, all patients with TcPO2≥ 40 mmHg achieved wound closure. Measurement of TcPO2 in the supine position revealed a cut-point value of 25 mmHg as the best threshold for predicting diabetic foot ulcer healing; the area under the curve using this cut-point was 0.838 (95% confidence interval = 0.700-0.976). The sensitivity, specificity, positive predictive value, and negative predictive value for TxPO2 were 88.6%, 82.4%, 90.7%, and 72.2%, respectively. TcPO2≥ 40 mmHg was associated with diabetic foot ulcer healing, but a TcPO2≤ 10 mmHg was associated with failure of wound healing. We found that a cut-point of 25 mmHg was most predictive of diabetic foot ulcer healing.

Thermal desorption of dimethyl methylphosphonate from MoO 3

DOE PAGES

Head, Ashley R.; Tang, Xin; Hicks, Zachary; ...

2017-03-03

Organophosphonates are used as chemical warfare agents, pesticides, and corrosion inhibitors. New materials for the sorption, detection, and decomposition of these compounds are urgently needed. To facilitate materials and application innovation, a better understanding of the interactions between organophosphonates and surfaces is required. To this end, we have used diffuse reflectance infrared Fourier transform spectroscopy to investigate the adsorption geometry of dimethyl methylphosphonate (DMMP) on MoO 3, a material used in chemical warfare agent filtration devices. We further applied ambient pressure X-ray photoelectron spectroscopy and temperature programmed desorption to study the adsorption and desorption of DMMP. While DMMP adsorbs intactmore » on MoO 3, desorption depends on coverage and partial pressure. At low coverages under UHV conditions, the intact adsorption is reversible. Decomposition occurs with higher coverages, as evidenced by PCH x and PO x decomposition products on the MoO 3 surface. Heating under mTorr partial pressures of DMMP results in product accumulation.« less

A dual electrochemical microsensor for simultaneous imaging of oxygen and pH over the rat kidney surface.

PubMed

Ha, Yejin; Myung, Dongshin; Shim, Jun Ho; Kim, Myung Hwa; Lee, Youngmi

2013-09-21

In this study, a dual microsensing electrochemical probe for measuring oxygen (O2) and pH levels was developed based on a dual recessed Pt disk electrode (each disk diameter, 10 μm) with the use of two Ag/AgCl reference electrodes (one for each disk of the dual electrode). One of the recessed Pt disks of the dual electrode was electrodeposited with a porous Pt layer and then coated with a hydrophobic photocured polymer (partially fluorinated epoxy diacrylate, abbreviated as FED). The Pt-FED covered disk was used as an amperometric O2 sensor and exhibited a linear current increase that was proportional to the PO2 level (partial O2 pressure) with high sensitivity (168.4 ± 33.8 pA mmHg(-1)) and fast response time (t90% = 0.17 ± 0.05 s). The other recessed Pt disk was electrodeposited with an IrO2 layer. The potential between the IrO2 deposited electrode and the Ag/AgCl reference electrode produced a reliable Nernstian response to pH changes (58.3 ± 1.5 mV pH(-1)) with a t90% of 0.43 ± 0.09 s. The sensor displayed high stability in the in vitro organ tissue measurements for at least 2.5 h. By using the developed dual O2/pH microsensor as a probe tip for scanning electrochemical microscopy, the two-dimensional images of the location-dependent PO2 and pH levels were simultaneously acquired and could be used to assess the surface of a rat kidney tissue slice. When compared to the corresponding medullary levels, both PO2 and pH were observed to be higher in the cortex area, while the modest level gradient was observed near the cortex-medulla border. This finding suggests that there is a direct relationship between the tissue O2 supply/consumption and pH, which is mainly determined by metabolite, such as CO2, production.

Analysis of Arterial and Venous Blood Gases in Healthy Gyr Falcons ( Falco rusticolus ) Under Anesthesia.

PubMed

Raghav, Raj; Middleton, Rachael; BSc, Rinshiya Ahamed; Arjunan, Raji; Caliendo, Valentina

2015-12-01

Arterial and venous blood gas analysis is useful in the assessment of tissue oxygenation and ventilation and in diagnosis of metabolic and respiratory derangements. It can be performed with a relatively small volume of blood in avian patients under emergency situations. Arterial and venous blood gas analysis was performed in 30 healthy gyr falcons ( Falco rusticolus ) under anaesthesia to establish temperature-corrected reference intervals for arterial blood gas values and to compare them to temperature-corrected venous blood gas values with a portable point-of-care blood gas analyzer (i-STAT 1, Abbott Laboratories, Abbott Park, IL, USA). Statistically significant differences were observed between the temperature-corrected values of pH, partial pressure of carbon dioxide (Pco2), and partial pressure of oxygen (Po2) and the corresponding nontemperature-corrected values of these parameters in both arterial and venous blood. Values of temperature-corrected pH, temperature-corrected Pco2, bicarbonate concentrations, and base excess of extra cellular fluid did not differ significantly between arterial and venous blood, suggesting that, in anesthetized gyr falcons, venous blood gas analysis can be used in place of arterial blood gas analysis in clinical situations. Values for hematocrit, measured by the point-of-care analyzer, were significantly lower compared with those obtained by the microhematocrit method.

The highly selective oxidation of cyclohexane to cyclohexanone and cyclohexanol over VAlPO4 berlinite by oxygen under atmospheric pressure.

PubMed

Hong, Yun; Sun, Dalei; Fang, Yanxiong

2018-04-04

The oxidation of cyclohexane under mild conditions occupies an important position in the chemical industry. A few soluble transition metals were widely used as homogeneous catalysts in the industrial oxidation of cyclohexane. Because heterogeneous catalysts are more manageable than homogeneous catalysts as regards separation and recycling, in our study, we hydrothermally synthesized and used pure berlinite (AlPO 4 ) and vanadium-incorporated berlinite (VAlPO 4 ) as heterogeneous catalysts in the selective oxidation of cyclohexane with molecular oxygen under atmospheric pressure. The catalysts were characterized by means of by XRD, FT-IR, XPS and SEM. Various influencing factors, such as the kind of solvents, reaction temperature, and reaction time were investigated systematically. The XRD characterization identified a berlinite structure associated with both the AlPO 4 and VAlPO 4 catalysts. The FT-IR result confirmed the incorporation of vanadium into the berlinite framework for VAlPO 4 . The XPS measurement revealed that the oxygen ions in the VAlPO 4 structure possessed a higher binding energy than those in V 2 O 5 , and as a result, the lattice oxygen was existed on the surface of the VAlPO 4 catalyst. It was found that VAlPO 4 catalyzed the selective oxidation of cyclohexane with molecular oxygen under atmospheric pressure, while no activity was detected on using AlPO 4 . Under optimum reaction conditions (i.e. a 100 mL cyclohexane, 0.1 MPa O 2 , 353 K, 4 h, 5 mg VAlPO 4 and 20 mL acetic acid solvent), a selectivity of KA oil (both cyclohexanol and cyclohexanone) up to 97.2% (with almost 6.8% conversion of cyclohexane) was obtained. Based on these results, a possible mechanism for the selective oxidation of cyclohexane over VAlPO 4 was also proposed. As a heterogeneous catalyst VAlPO 4 berlinite is both high active and strong stable for the selective oxidation of cyclohexane with molecular oxygen. We propose that KA oil is formed via a catalytic cycle, which involves activation of the cyclohexane by a key active intermediate species, formed from the nucleophilic addition of the lattice oxygen ion with the carbon in cyclohexane, as well as an oxygen vacancy formed at the VAlPO 4 catalyst surface.

Estimation of changes in alveolar-arterial oxygen gradient induced by hypoxia.

PubMed

Hoffstein, V; Duguid, N; Zamel, N; Rebuck, A S

1984-11-01

The alveolar-arterial oxygen tension difference provides a useful clinical indication of ventilation-blood flow mismatching in the lungs. In some clinical situations involving alveolar hypoxia (e.g., patients with chronic obstructive lung disease flying in commercial aircraft or normal humans at high altitudes) it would be useful to know this tension difference to predict the likely arterial PO2 under such potentially stressful conditions. Such estimates would require multiple arterial punctures performed under a variety of trying circumstances, conditions usually far distant from a suitable analytic facility. Consequently, we induced controlled hypoxia in 23 healthy humans and calculated changes in the alveolar-arterial oxygen tension difference during the hypoxic challenge test. We plotted this difference as a function of the alveolar oxygen tension over a range from 35 to 110 mm Hg. In addition to a series of control studies in which multiple arterial blood samples were obtained, we calculated arterial PO2 by converting the arterial oxyhemoglobin saturation (measured with an ear oximeter) into partial pressure of oxygen. During hypoxic procedures in which levels of oxygenation fell on the steep section of the oxyhemoglobin dissociation curve, fixing PCO2 at constant predetermined levels allowed accurate predictions of arterial PO2. We were able to demonstrate that the alveolar-arterial oxygen tension difference narrowed with decreasing alveolar oxygen tension, and that measurement with an ear oximeter provided data that allowed a reasonable estimate of the tension difference during hypoxic conditions.

Mechanical versus humoral determinants of brain death-induced lung injury

PubMed Central

Dewachter, Laurence; Rorive, Sandrine; Remmelink, Myriam; Weynand, Birgit; Melot, Christian; Hupkens, Emeline; Dewachter, Céline; Creteur, Jacques; Mc Entee, Kathleen; Naeije, Robert; Rondelet, Benoît

2017-01-01

Background The mechanisms of brain death (BD)-induced lung injury remain incompletely understood, as uncertainties persist about time-course and relative importance of mechanical and humoral perturbations. Methods Brain death was induced by slow intracranial blood infusion in anesthetized pigs after randomization to placebo (n = 11) or to methylprednisolone (n = 8) to inhibit the expression of pro-inflammatory mediators. Pulmonary artery pressure (PAP), wedged PAP (PAWP), pulmonary vascular resistance (PVR) and effective pulmonary capillary pressure (PCP) were measured 1 and 5 hours after Cushing reflex. Lung tissue was sampled to determine gene expressions of cytokines and oxidative stress molecules, and pathologically score lung injury. Results Intracranial hypertension caused a transient increase in blood pressure followed, after brain death was diagnosed, by persistent increases in PAP, PCP and the venous component of PVR, while PAWP did not change. Arterial PO2/fraction of inspired O2 (PaO2/FiO2) decreased. Brain death was associated with an accumulation of neutrophils and an increased apoptotic rate in lung tissue together with increased pro-inflammatory interleukin (IL)-6/IL-10 ratio and increased heme oxygenase(HO)-1 and hypoxia inducible factor(HIF)-1 alpha expression. Blood expressions of IL-6 and IL-1β were also increased. Methylprednisolone pre-treatment was associated with a blunting of increased PCP and PVR venous component, which returned to baseline 5 hours after BD, and partially corrected lung tissue biological perturbations. PaO2/FiO2 was inversely correlated to PCP and lung injury score. Conclusions Brain death-induced lung injury may be best explained by an initial excessive increase in pulmonary capillary pressure with increased pulmonary venous resistance, and was associated with lung activation of inflammatory apoptotic processes which were partially prevented by methylprednisolone. PMID:28753621

Ocular oxygen consumption: estimates using vitreoperfusion in the cat.

PubMed

Blair, Norman P; Liu, Ting; Warren, Keith A; Glaser, David A; Kennedy, Marc; Tran, Huan; Larson, Christopher A; Atluri, Prasant; Saidel, Michael A; Blair, Michael P

2004-02-01

Little is known about the ocular oxygen consumption rate (QO2) in human diseases. Alterations in QO2 must occur in many conditions, such as retinal ischemia. We present a method of estimating QO2 that eventually could be used in patients during vitrectomy surgery. We performed vitreoperfusion (i.e., perfusion of the vitreous cavity after vitrectomy) in 14 cat eyes with no ocular blood flow. The solution contained nutrients at a high partial pressure of oxygen (PO2). In eight eyes, the retinas were undisturbed (Group 1), and in six eyes, we excised the retinas (Group 2). We estimated QO2 in both groups on the basis of the temporal decline of PO2 in the vitreoperfusion solution according to a pharmacokinetic model. The mean and standard deviation of QO2 was 3.2 +/- 0.8 microL/min in Group 1 and 0.4+/- 0.7 microL/min in Group 2, with the difference being the retinal contribution, 88%. In Group 1, metabolism, bulk flow, and diffusion accounted for 82, 13, and 5%, respectively, of the oxygen loss from the vitreoperfusion solution. We estimated ocular oxygen consumption by means of vitreoperfusion. Eventually, the pathophysiology of human diseases may be clarified by similar measurements during vitrectomy.

Investigating the stability of cathode materials for rechargeable lithium ion batteries

NASA Astrophysics Data System (ADS)

Huang, Yiqing

Lithium ion batteries are widely used in portable electronic devices and electric vehicles. However, safety is one of the most important issues for the Li-ion batteries' use. Some cathode materials, such as LiCoO 2, are thermally unstable in the charged state. Upon decomposition these cathode materials release O2, which could react with organic electrolyte, leading to a thermal runaway. Thus understanding the stability of the cathode materials is critical to the safety of lithium ion batteries. Olivine-type LiMnPO4 is a promising cathode material for lithium ion batteries because of its high energy density. We have revealed the critical role of carbon in the stability and thermal behaviour of olivine MnPO 4 obtained by chemical delithiation of LiMnPO4. (Li)MnPO 4 samples with various particle sizes and carbon contents were studied. Carbon-free LiMnPO4 obtained by solid state synthesis in O 2 becomes amorphous upon delithiation. Small amounts of carbon (0.3 wt.%) help to stabilize the olivine structure, so that completely delithiated crystalline olivine MnPO4 can be obtained. Larger amount of carbon (2 wt.%) prevents full delithiation. Heating in air, O2, or N 2 results in structural disorder (< 300 °C), formation of an intermediate sarcopside Mn3(PO4)2 phase (350 -- 450 °C), and complete decomposition to Mn2P2O 7 on extended heating at 400 °C. Carbon protects MnPO4 from reacting with environmental water, which is detrimental to its structural stability. We not only studied the crystalline olivine MnPO4, but also investigated the amorphous products obtained from carbon-free LiMnPO 4. We have revealed the Mn dissolution phenomenon during chemical delithiation of LiMnPO4, which causes the amorphization of olivine MnPO 4. Properties of crystalline-MnPO4 obtained from carbon-coated LiMnPO4 and of amorphous product resulting from the delithiation of pure LiMnPO4 were studied and compared. The P-rich amorphous phases in the latter are considered to be MnHP2O7 and MnH2P2O7 from XAS and XPS analysis. Safety of batteries not only depends on the stability of the active materials, but also the interactions between the active materials and electrolyte. Thus we study the stability between the cathode materials and the electrolyte. The thermal stability of electrochemically delithiated Li0.1N 0.8C0.15Al0.05O2 (NCA), FePO4 (FP), Mn0.8Fe0.2PO4 (MFP), hydrothermally synthesized VOPO4, LiVOPO4 and electrochemically lithiated Li2VOPO4 is investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis, coupled with mass spectrometry (TGA-MS). The thermal stability is found in the order: NCA< VOPO4< MFP< FP=LiVOPO4=Li2VOPO4. Sealed capsule high pressure experiments show a phase transformation of VOPO4 → HVOPO4 → H2VOPO4 when VOPO4 reacts with electrolyte (1 M LiPF6 in EC: DMC=1:1) between 200 and 300 °C. Finally, we characterize the lithium storage and release mechanism of V2O5 aerogels by x-ray photoelectron spectroscopy (XPS). We study the influence of n--butyllithium (n--BuLi) treatments on the electrochemical performance of the aerogel. In addition to fully reversible V reduction and oxidation due to the intercalation reaction, we observe the formation of LiOH species that are only partially reversible. This is attributed to reaction with the interlayer water and is considered responsible for the gradual capacity fade. The n--BuLi treated aerogels display a higher capacity than those without and our XPS analysis reveals an additional reversible formation of Li2O.

Ammonium iron(III) phosphate(V) fluoride, (NH4)0.5[(NH4)0.375K0.125]FePO4F, with ammonium partially substituted by potassium

PubMed Central

Wang, Lei; Zhou, Yan; Huang, Ya-Xi; Mi, Jin-Xiao

2009-01-01

The title compound, ammonium potassium iron(III) phosphate fluoride, (NH4)0.875K0.125FePO4F, is built from zigzag chains ∞ 1{[FeO4F2]7−}, with Fe3+ in a distorted octahedral coordination, extending along both the [011] and [01] directions. These chains are made up of alternating trans-[FeO4F2] and cis-[FeO4F2] octa­hedra via shared F-atom corners, and are linked by PO4 tetra­hedra, resulting in an open-framework structure with channels along the [010] and [100] directions. There are two crystallographically independent ammonium sites: one in the [010] channels and the other, partially substituted by K+ ions, in the [100] channels. The ammonium in the [010] channels is fixed to the framework via eight hydrogen bonds (six N—H⋯O and two N—H⋯F). PMID:21581466

Synthesis, Characterization, and Electrochemical Behavior of LiMnxFe(1−x)PO4 Composites Obtained from Phenylphosphonate-Based Organic-Inorganic Hybrids

PubMed Central

Dell’Era, Alessandro; Pasquali, Mauro; Bauer, Elvira Maria; Lupi, Carla

2017-01-01

The synthesis of organic-inorganic hybrid compounds based on phenylphosphonate and their use as precursors to form LiMnxFe(1−x)PO4 composites containing carbonaceous substances with sub-micrometric morphology are presented. The experimental procedure includes the preliminary synthesis of Fe2+ and/or Mn2+ phenylphosphonates with the general formula Fe(1−x)Mnx[(C6H5PO3)(H2O)] (with 0 < x < 1), which are then mixed at different molar ratios with lithium carbonate. In this way the carbon, obtained from in situ partial oxidation of the precursor organic part, coats the LiMnxFe(1−x)PO4 particles. After a structural and morphological characterization, the electrochemical behavior of lithium iron manganese phosphates has been compared to the one of pristine LiFePO4 and LiMnPO4, in order to evaluate the doping influence on the material. PMID:29301206

Off-pump versus on-pump coronary artery revascularization: effects on pulmonary function.

PubMed

e Silva, Ana M R P; Saad, Roberto; Stirbulov, Roberto; Rivetti, Luiz A

2010-07-01

Many studies have shown important changes in lung function tests after coronary artery surgeries. It is controversial if off-pump surgery can give a better and shorter recovery than the on-pump. A prospective study was conducted on 42 patients submitted to coronary artery surgery and divided into two groups: 21 off-pump using intraluminal shunt (G (I)) and 21 on-pump (G (II)), matched by the anatomical location of the coronary arteries lesions. All patients had spirometric evaluation, blood gas measurements and alveolo-arterial oxygen gradient (A-aDO(2)), at the fourth and 10th postoperative days (PO(4) and PO(10)). Preoperatively, G(I) and G(II) had similar results (P>0.372). Spirometry showed decreases at PO(4) and remained decreased until PO(10) for both groups, with significant differences between the groups. The blood gas measurements showed reduction in arterial oxygen pressure (PaO(2)) and carbon dioxide pressure (PaCO(2)), while there was an increase in A-aDO(2) at PO(4) and PO(10) in both groups. The results suggest that different changes occur in pulmonary function when the surgery is performed with or without cardiopulmonary bypass. The off-pump patients showed significantly greater improvement than the on-pump group.

Thermodynamics Behavior of Germanium During Equilibrium Reactions between FeOx-CaO-SiO2-MgO Slag and Molten Copper

NASA Astrophysics Data System (ADS)

Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S.; Reuter, M. A.

2016-10-01

The distribution ratio of germanium (Ge), L_{{Ge}}^{s/m} during equilibrium reactions between magnesia-saturated FeOx-CaO-SiO2 (FCS) slag and molten copper has been measured under oxygen partial pressures from 10-10 to 10-7 atm and at temperatures 1473 to 1623 K (1200 to 1350 °C). It was observed that the Ge distribution ratio increases with increasing oxygen partial pressure, and with decreasing temperature. It was also observed that the distribution ratio is strongly dependent on slag basicity. The distribution ratio was observed to increase with increasing optical basicity. At fixed CaO concentration in the slag, the distribution ratio was found to increase with increasing Fe/SiO2 ratio, tending to a plateau at L_{{Ge}}^{s/m} = 0.8. This behavior is consistent with the assessment of ionic bond fraction carried out in this study, and suggested the acidic nature of germanium oxide (GeO2) in the slag system studied. The characterisation results of the quenched slag suggested that Ge is present in the FeOx-CaO-SiO2-MgO slag predominantly as GeO2. At 1573 K (1300 °C) and p_{{{{O}}2 }} = 10-8 atm, the activity coefficient of GeO2 in the slag was calculated to be in the range of 0.24 to 1.50. The results from the current study suggested that less-basic slag, high operating temperature, and low oxygen partial pressure promote a low Ge distribution ratio. These conditions are desired for maximizing Ge recovery, for example, during pyrometallurgical processing of Ge-containing e-waste through secondary copper smelting. Overall, the thermodynamics data generated from this study can be used for process modeling purposes for improving recovery of Ge in primary and secondary copper smelting processes.

Blood gas and serum biochemical RIs for healthy newborn Murrah buffaloes (Bubalus bubalis).

PubMed

Santana, André M; Silva, Daniela G; Clemente, Virna; Pizauro, Lucas J L; Bernardes, Priscila A; Santana, Clarissa H; Eckersall, Peter D; Fagliari, José J

2018-03-01

There is a lack of published work on RIs for newborn buffaloes. Establishing blood gas and serum biochemical RIs for newborn buffaloes is important for monitoring health. This study establishes blood gas and serum biochemical RIs of newborn buffaloes. Twenty-eight newborn buffaloes, 10-30 days old, were selected. Thirty blood biochemical variables were analyzed. The Anderson-Darling test was used to assess the normality of the distribution. The Dixon test and the Tukey test were used to identify outliers. The RI and 90% CI were determined using standard and robust methods and the Box-Cox transformation. A total of 30 RIs for healthy buffalo calves have been reported in this study. RIs for blood gas variables were reported for pH, partial pressure of oxygen (pO 2 ), partial pressure of carbon dioxide (pCO 2 ), saturation of O 2 (SO 2 ), bicarbonate (cHCO 3 - ), base excess (BE), total carbon dioxide (ctCO 2 ), and anion gap (AG). RIs for serum biochemical variables were reported for glucose (GLU), direct bilirubin (DB), total bilirubin (TB), AST, ALP, GGT, CK, LDH, creatinine (CREA), urea, cholesterol (CHOL), triglycerides (TG), Ca, P, Mg, Na, K, iCa, Cl, iron, total protein (TP), and albumin (ALB). This is the first reported study covering complete serum chemistry and blood gas RIs for healthy 1-month-old Murrah buffaloes. © 2018 American Society for Veterinary Clinical Pathology.

Effects of handling intensity and live weight on blood acid-base status in finishing pigs.

PubMed

Hamilton, D N; Ellis, M; Bertol, T M; Miller, K D

2004-08-01

The objective of this study was to determine the effect of live weight on the plasma acid-base response of pigs subjected to various handling intensities. Eighty pigs (equal numbers of barrows and gilts) were used in a completely randomized block design with a 2 x 2 x 2 factorial arrangement of the following treatments: 1) live weight (light [104 kg] vs. heavy [128 kg]), 2) handling intensity (low vs. high), and 3) gender (barrows vs. gilts). Before the handling test, pigs were weighed, venous blood samples were taken to establish baseline levels, and rectal temperature was measured. Pigs were allowed to rest for 2 h before being subjected to the handling treatments, which consisted of moving the pigs through a course (12.2 m long x 0.91 m wide), for a total of eight laps. Animals on the high-intensity treatment were moved rapidly through the course and subjected to a total of 16 single shocks (two shocks per lap) with an electric livestock goad, whereas pigs on the low-intensity treatment were moved at their own pace using a moving panel and a paddle. Rectal temperature and a venous blood sample were taken immediately after handling and at 2 h after handling. Blood plasma was assayed for pH, partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), saturated oxygen (SO2), total carbon dioxide (TCO2), bicarbonate (HCO3), base excess, and lactate. Live weight had no effect on the baseline measurements. After handling, light pigs had higher (P < 0.05) blood SO2 (65.6 vs. 57.2+/-2.80%) and showed a greater (P < 0.05) increase in PO2 from baseline to post-handling than heavy pigs (15.6 vs. 8.3+/-2.63 mmHg). Post-handling, pigs on the high- compared with the low-intensity handling treatment had greater (P < 0.001) lactate (19.1 vs. 4.9+/-0.56 mmol/L) and PO2 (51.6 vs. 36.5+/-2.44 mmHg) with lower (P < 0.001) TCO2 (18.6 vs. 34.7+/-0.64 mmol/L), pH (7.02 vs. 7.36+/-0.015), HCO3 (16.7 vs. 33.0+/-0.62 mmol/L), and base excess (-14.2 vs. 7.5+/-0.75) values. There were no effects of gender on blood measurements or rectal temperatures. Results from this study highlight a major effect of pig handling intensity, a limited effect of live weight, and no effect of gender on blood acid-base responses to handling.

Continuous Real-time Viability Assessment of Kidneys Based on Oxygen Consumption

PubMed Central

Weegman, B.P.; Kirchner, V.A.; Scott, W.E.; Avgoustiniatos, E.S.; Suszynski, T.M.; Ferrer-Fabrega, J.; Rizzari, M.D.; Kidder, L.S.; Kandaswamy, R.; Sutherland, D.E.R.; Papas, K.K.

2010-01-01

Background Current ex vivo quality assessment of donor kidneys is limited to vascular resistance measurements and histological analysis. New techniques for the assessment of organ quality before transplantation may further improve clinical outcomes while expanding the depleted deceased-donor pool. We propose the measurement of whole organ oxygen consumption rate (WOOCR) as a method to assess the quality of kidneys in real time before transplantation. Methods Five porcine kidneys were procured using a donation after cardiac death (DCD) model. The renal artery and renal vein were cannulated and the kidney connected to a custom-made hypothermic machine perfusion (HMP) system equipped with an inline oxygenator and fiber-optic oxygen sensors. Kidneys were perfused at 8°C, and the perfusion parameters and partial oxygen pressures (pO2) were measured to calculate WOOCR. Results Without an inline oxygenator, the pO2 of the perfusion solution at the arterial inlet and venous outlet diminished to near 0 within minutes. However, once adequate oxygenation was provided, a significant pO2 difference was observed and used to calculate the WOOCR. The WOOCR was consistently measured from presumably healthy kidneys, and results suggest that it can be used to differentiate between healthy and purposely damaged organs. Conclusions Custom-made HMP systems equipped with an oxygenator and inline oxygen sensors can be applied for WOOCR measurements. We suggest that WOOCR is a promising approach for the real-time quality assessment of kidneys and other organs during preservation before transplantation. PMID:20692397

Pressure overload-dependent membrane type 1-matrix metalloproteinase induction: relationship to LV remodeling and fibrosis.

PubMed

Zile, Michael R; Baicu, Catalin F; Stroud, Robert E; Van Laer, An; Arroyo, Jazmine; Mukherjee, Rupak; Jones, Jeffrey A; Spinale, Francis G

2012-04-01

Increased myocardial extracellular matrix collagen represents an important structural milestone during the development of left ventricular (LV) pressure overload (PO); however, the proteolytic pathways that contribute to this process are not fully understood. This study tested the hypothesis that membrane type 1-matrix metalloproteinase (MT1-MMP) is directly induced at the transcriptional level in vivo during PO and is related to changes in LV collagen content. PO was induced in vivo by transverse aortic constriction in transgenic mice containing the full length human MT1-MMP promoter region ligated to luciferase (MT1-MMP Prom mice). MT1-MMP promoter activation (luciferase expression), expression, and activity; collagen volume fraction (CVF); and left atrial dimension were measured at 1 (n = 8), 2 (n = 12), and 4 (n = 17) wk following PO. Non-PO mice (n = 10) served as controls. Luciferase expression increased by fivefold at 1 wk, fell at 2 wk, and increased again by ninefold at 4 wk of PO (P < 0.05). MT1-MMP expression and activity increased at 1 wk, fell at 2 wk, and increased again at 4 wk after PO. CVF increased at 1 wk, remained unchanged at 2 wk, and increased by threefold at 4 wk of PO (P < 0.05). There was a strong positive correlation between CVF and MT1-MMP activity (r = 0.80, P < 0.05). Left atrial dimension remained unchanged at 1 and 2 wk but increased by 25% at 4 wk of PO. When a mechanical load was applied in vitro to LV papillary muscles isolated from MT1-MMP Prom mice, increased load caused MT1-MMP promoter activation to increase by twofold and MT1-MMP expression to increase by fivefold (P < 0.05). These findings challenge the canonical belief that PO suppresses overall matrix proteolytic activity, but rather supports the concept that certain proteases, such as MT1-MMP, play a pivotal role in PO-induced matrix remodeling and fibrosis.

NASICON-related Na3.4Mn0.4Fe1.6(PO4)3

PubMed Central

Yatskin, Michael M.; Strutynska, Nataliya Yu.; Baumer, Vyacheslav N.; Ogorodnyk, Ivan V.; Slobodyanik, Nikolay S.

2012-01-01

The solid solution, sodium [iron(III)/manganese(II)] tris­(orthophosphate), Na3.4Mn0.4Fe1.6(PO4)3, was obtained using a flux method. Its crystal structure is related to that of NASICON-type compounds. The [(Mn/Fe)2(PO4)3] framework is built up from an (Mn/Fe)O6 octa­hedron (site symmetry 3.), with a mixed Mn/Fe occupancy, and a PO4 tetra­hedron (site symmetry .2). The Na+ cations are distributed over two partially occupied sites in the cavities of the framework. One Na+ cation (site symmetry -3.) is surrounded by six O atoms, whereas the other Na+ cation (site symmetry .2) is surrounded by eight O atoms. PMID:22807697

Analysis of laser induced plasma of lithium iron phosphate/LiFePO4 using Nd:YAG laser at low pressure

NASA Astrophysics Data System (ADS)

Suliyanti, M. M.; Hidayah, A. N.; Isnaeni

2017-04-01

Preliminary analysis of lithium in Lithium Iron Phosphate (LiFePO4) powder using laser induced plasma spectroscopy at low pressure had been done. Recently, LiFePO4-based batteries are widely used in most electric cars and bikes due to less toxic. However, lithium (Li) element is very difficult to detect since it is a very light element. In this work, we used a Nd:YAG laser (1064 nm wavelength, 5 ns pulse width at 10 Hz repetition rate) that was focused on LiFePO4 sample at low pressure. The main Li peak emission in LiFePO4 powder and sheet can be easily detected using this technique. We report the results of experimental study on Li element emission lines at wavelength 460.18 nm, 610.37 nm and 670.83 nm using 2 mJ and 12 mJ laser irradiation at 5 Torr and 35 Torr air atmosphere. The results of this study showed promising application of laser-induced plasma spectroscopy to detect and analyse Li in various samples.

Temporal and Molecular Analyses of Cardiac Extracellular Matrix Remodeling following Pressure Overload in Adiponectin Deficient Mice

PubMed Central

Dadson, Keith; Turdi, Subat; Boo, Stellar; Hinz, Boris; Sweeney, Gary

2015-01-01

Adiponectin, circulating levels of which are reduced in obesity and diabetes, mediates cardiac extracellular matrix (ECM) remodeling in response to pressure overload (PO). Here, we performed a detailed temporal analysis of progressive cardiac ECM remodelling in adiponectin knockout (AdKO) and wild-type (WT) mice at 3 days and 1, 2, 3 and 4 weeks following the induction of mild PO via minimally invasive transverse aortic banding. We first observed that myocardial adiponectin gene expression was reduced after 4 weeks of PO, whereas increased adiponectin levels were detected in cardiac homogenates at this time despite decreased circulating levels of adiponectin. Scanning electron microscopy and Masson’s trichrome staining showed collagen accumulation increased in response to 2 and 4 weeks of PO in WT mice, while fibrosis in AdKO mice was notably absent after 2 weeks but highly apparent after 4 weeks of PO. Time and intensity of fibroblast appearance after PO was not significantly different between AdKO and WT animals. Gene array analysis indicated that MMP2, TIMP2, collagen 1α1 and collagen 1α3 were induced after 2 weeks of PO in WT but not AdKO mice. After 4 weeks MMP8 was induced in both genotypes, MMP9 only in WT mice and MMP1α only in AdKO mice. Direct stimulation of primary cardiac fibroblasts with adiponectin induced a transient increase in total collagen detected by picrosirius red staining and collagen III levels synthesis, as well as enhanced MMP2 activity detected via gelatin zymography. Adiponectin also enhanced fibroblast migration and attenuated angiotensin-II induced differentiation to a myofibroblast phenotype. In conclusion, these data indicate that increased myocardial bioavailability of adiponectin mediates ECM remodeling following PO and that adiponectin deficiency delays these effects. PMID:25910275

Oxidation of SUS-316 stainless steel for fast breeder reactor fuel cladding under oxygen pressure controlled by Ni/NiO oxygen buffer

NASA Astrophysics Data System (ADS)

Saito, Minoru; Furuya, Hirotaka; Sugisaki, Masayasu

1985-09-01

Oxidation of SUS-316 stainless steel for a fast breeder reactor fuel cladding was examined in the temperature range of 843-1010 K under the oxygen pressure of 1017 t - 10 t-13 Pa hy use of an experimental technique of a Ni/NiO oxygen buffer. The formation of the duplex oxide layer, i.e. an outer Fe 3O 4 layer and an inner (Fe, Cr, Ni)-spinel layer, was observed and the oxidation kinetics was found to obey the parabolic rate law. The oxygen pressure and temperature dependence of the parabolic rate constant kp( PO2, T) was determined as follows: kp( PO2, T)/ kg2 · m-1 · s-1 = 0.170( PO2/ Pa) 0.141exp[-114 × 10 3/( RT/ J)]. On the basis of the oxidation kinetics and the metallographic information, the outward diffusion of Fe in the outer oxide layer was assigned to be the rate-determining process.

Effects of Ca2+ on oxidative phosphorylation in mitochondria from the thermogenic organ of marlin.

PubMed

O'Brien, J; Block, B A

1996-12-01

Mitochondria from the muscle-derived thermogenic (heater) organ and oxidative red muscle of the blue marlin (Makaira nigricans) were studied in order to evaluate aspects of the mechanism of thermogenesis in heater tissue. We investigated whether short-term Ca(2+)-induced uncoupling of mitochondria contributes to the thermogenic cycle of the heater organ by enhancing the respiration rate. Specific electrodes were used to obtain simultaneous measurements of oxygen consumption and Ca2+ fluxes on isolated mitochondria, and the effects of various concentrations of Ca2+ on respiration rates and the ADP phosphorylated/atomic oxygen consumed (P/O) ratio were examined. Addition of Ca2+ in excess of 10 mumol l-1 to respiring heater organ or red muscle mitochondria partially inhibited state 3 respiration and reduced the P/O ratio, indicating that the mitochondria were partially uncoupled. These effects were blocked by 2 mumol l-1 Ruthenium Red. In heater organ mitochondria, state 3 respiration rate and the P/O ratio were not significantly reduced by 1 mumol l-1 free Ca2+, a concentration likely to be near the maximum achieved in a stimulated cell. This indicates that transient increases in cytosolic Ca2+ concentration may not significantly reduce the P/O ratio of heater organ mitochondria. The activity of 2-oxoglutarate dehydrogenase in heater organ mitochondria was stimulated by approximately 15% by Ca2+ concentrations between 0.2 and 1 mumol l-1. These results suggest that heater organ mitochondria are able to maintain a normal P/O ratio and should maintain ATP output during transient increases in Ca2+ concentration, supporting a model in which an ATP-consuming process drives thermogenesis. Activation of mitochondrial dehydrogenases by low levels of Ca2+ may also enhance respiration and contribute to thermogenesis.

Occlusion pressures in men rebreathing CO2 under methoxyflurane anesthesia.

PubMed

Derenne, J P; Couture, J; Iscoe, S; Whitelaw, A; Milic-Emili, J

1976-05-01

The effect of general anesthesia on control of breathing was studied by CO2 rebreathing and occlusion pressure measurements in six normal human subjects under methoxyflurane anesthesia. CO2 was found to increase the amplitude of the occlusion pressure wave without changing its shape, so that CO2 responses in terms of the occlusion pressure developed 100 ms after the onset of inspiration (Po/0.1) gave results equivalent to the responses in terms of Po/1.o or any other parameter of the pressure wave. Methoxyflurane depressed the ventilatory response to CO2 but not the occlusion pressure response, implying that the most important action of the anesthetic was to increase the effective elastance of the respiratory system rather than to depress the respiratory centers. The elastance was further increased by CO2, and this mechanical change had the effect of shifting the "apneic threshold" extrapolated from the ventilatory response curve to a lower PAco2. Frequency of breathing, inspiratory and expiratory times were not altered by CO2 in anesthetized subjects.

Donor lung assessment using selective pulmonary vein gases.

PubMed

Costa, Joseph; Sreekanth, Sowmyashree; Kossar, Alex; Raza, Kashif; Lederer, David J; Robbins, Hilary; Shah, Lori; Sonett, Joshua R; Arcasoy, Selim; D'Ovidio, Frank

2016-11-01

Standard donor lung assessment relies on imaging, challenge gases and subjective interpretation of bronchoscopic findings, palpation and visual assessment. Central gases may not accurately represent true quality of the lungs. We report our experience using selective pulmonary vein gases to corroborate the subjective judgement. Starting, January 2012, donor lungs have been assessed by intraoperative bronchoscopy, palpation and visual judgement of lung collapse upon temporary disconnection from ventilator, central gases from the aorta and selective pulmonary vein gases. Partial pressure of oxygen (pO 2 ) <300 mmHg on FiO 2 of 1.0 was considered low. The results of the chest X-ray and last pO 2 in the intensive care unit were also collected. Post-transplant primary graft dysfunction and survival were monitored. To date, 259 consecutive brain-dead donors have been assessed and 157 transplants performed. Last pO 2 in the intensive care unit was poorly correlated with intraoperative central pO 2 (Spearman's rank correlation r s = 0.29). Right inferior pulmonary vein pO 2 was associated (Mann-Whitney, P < 0.001) with findings at bronchoscopy [clean: median pO 2 443 mmHg (25th-75th percentile range 349-512) and purulent: 264 mmHg (178-408)]; palpation [good: 463 mmHg (401-517) and poor: 264 mmHg (158-434)] and visual assessment of lung collapse [good lung collapse: 429 mmHg (320-501) and poor lung collapse: 205 mmHg (118-348)]. Left inferior pulmonary pO 2 was associated (P < 0.001) with findings at bronchoscopy [clean: 419 mmHg (371-504) and purulent: 254 mmHg (206-367)]; palpation [good: 444 mmHg (400-517) and poor 282 mmHg (211-419)] and visual assessment of lung collapse [good: 420 mmHg (349-496) and poor: 246 mmHg (129-330)]. At 72 h, pulmonary graft dysfunction 2 was in 21/157 (13%) and pulmonary graft dysfunction 3 in 17/157 (11%). Ninety-day and 1-year mortalities were 6/157 (4%) and 13/157 (8%), respectively. Selective pulmonary vein gases provide corroborative objective support to the findings at bronchoscopy, palpation and visual assessment. Central gases do not always reflect true function of the lungs, having high false-positive rate towards the individual lower lobe gas exchange. Objective measures of donor lung function may optimize donor surgeon assessment, allowing for low pulmonary graft dysfunction rates and low 90-day and 1-year mortality. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Oxygen partial pressure effects on metabolic rate and behavior of tethered flying locusts.

PubMed

Rascón, Brenda; Harrison, Jon F

2005-11-01

Resting insects are extremely tolerant of hypoxia. However, oxygen requirements increase dramatically during flight. Does the critical atmospheric P (O)(2) (P(c)) increase strongly during flight, or does increased tracheal conductance allow even flying insects to possess large safety margins for oxygen delivery? We tested the effect of P(O)(2) on resting and flying CO(2) emission, as well as on flight behavior and vertical force production in flying locusts, Schistocerca americana. The P(c) for CO(2) emission of resting animals was less than 1 kPa, similar to prior studies. The P(c) for flight bout duration was between 10 and 21 kPa, the P(c) for vertical force production was between 3 and 5 kPa, and the P(c) for CO(2) emission was between 10 and 21 kPa. Our study suggests that the P(c) for steady-state oxygen consumption is between 10 and 21 kPa (much higher than for resting animals), and that tracheal oxygen stores allowed brief flights in 5 and 10 kPa P(O)(2) atmospheres to occur. Thus, P(c) values strongly increased during flight, consistent with the hypothesis that the excess oxygen delivery capacity observed in resting insects is substantially reduced during flight.

The effect of acute temperature increases on the cardiorespiratory performance of resting and swimming sockeye salmon (Oncorhynchus nerka).

PubMed

Steinhausen, M F; Sandblom, E; Eliason, E J; Verhille, C; Farrell, A P

2008-12-01

The mechanism underlying the decrease in aerobic scope in fish at warm temperatures is not fully understood and is the focus of this research. Our study examined oxygen uptake and delivery in resting, swimming and recovering sockeye salmon while water temperature was acutely increased from 15 degrees C to 24 degrees C in 2 degrees C h(-1) increments. Fish swam at a constant speed during the temperature change. By simultaneously measuring oxygen consumption (M(O(2))), cardiac output (Q) and the blood oxygen status of arterial and venous blood, we were able to determine where in the oxygen cascade a limitation appeared when fish stopped sustained swimming as temperature increased. High temperature fatigue of swimming sockeye salmon was not a result of a failure of either oxygen delivery to the gills or oxygen diffusion at the gills because oxygen partial pressure (P(O(2))) and oxygen content (C(O(2))) in arterial blood did not decrease with increasing temperature, as would be predicted for such limitations. Instead, arterial oxygen delivery (Ta(O(2))) was initially hampered due to a failure to adequately increase Q with increasing temperature. Subsequently, lactate appeared in the blood and venous P(O(2)) remained constant.

Exogenous and endogenous angiotensin-II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow.

PubMed

Emans, Tonja W; Janssen, Ben J; Pinkham, Maximilian I; Ow, Connie P C; Evans, Roger G; Joles, Jaap A; Malpas, Simon C; Krediet, C T Paul; Koeners, Maarten P

2016-11-01

Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary. We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats. This method provides stable and continuous measurements of cortical tissue oxygen tension (PO2) for more than 2 weeks and can reproducibly detect acute changes in cortical oxygenation. Exogenous angiotensin-II reduced renal cortical tissue PO2 more than equi-pressor doses of phenylephrine, probably because it reduced renal oxygen delivery more than did phenylephrine. Activation of the endogenous renin-angiotensin system in transgenic Cyp1a1Ren2 rats reduced cortical tissue PO2; in this model renal hypoxia precedes the development of structural pathology and can be reversed acutely by an angiotensin-II receptor type 1 antagonist. Angiotensin-II promotes renal hypoxia, which may in turn contribute to its pathological effects during development of chronic kidney disease. We hypothesised that both exogenous and endogenous angiotensin-II (AngII) can decrease the partial pressure of oxygen (PO2) in the renal cortex of unrestrained rats, which might in turn contribute to the progression of chronic kidney disease. Rats were instrumented with telemeters equipped with a carbon paste electrode for continuous measurement of renal cortical tissue PO2. The method reproducibly detected acute changes in cortical oxygenation induced by systemic hyperoxia and hypoxia. In conscious rats, renal cortical PO2 was dose-dependently reduced by intravenous AngII. Reductions in PO2 were significantly greater than those induced by equi-pressor doses of phenylephrine. In anaesthetised rats, renal oxygen consumption was not affected, and filtration fraction was increased only in the AngII infused animals. Oxygen delivery decreased by 50% after infusion of AngII and renal blood flow (RBF) fell by 3.3 ml min -1 . Equi-pressor infusion of phenylephrine did not significantly reduce RBF or renal oxygen delivery. Activation of the endogenous renin-angiotensin system in Cyp1a1Ren2 transgenic rats reduced cortical tissue PO2. This could be reversed within minutes by pharmacological angiotensin-II receptor type 1 (AT 1 R) blockade. Thus AngII is an important modulator of renal cortical oxygenation via AT 1 receptors. AngII had a greater influence on cortical oxygenation than did phenylephrine. This phenomenon appears to be attributable to the profound impact of AngII on renal oxygen delivery. We conclude that the ability of AngII to promote renal cortical hypoxia may contribute to its influence on initiation and progression of chronic kidney disease. © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Subcutaneous oxygen pressure in spontaneously breathing lean and obese volunteers: a pilot study.

PubMed

Hiltebrand, Luzius B; Kaiser, Heiko A; Niedhart, Dagmar J; Pestel, Gunther; Kurz, Andrea

2008-01-01

Oxidative killing is the primary defense against surgical pathogens; risk of infection is inversely related to tissue oxygenation. Subcutaneous tissue oxygenation in obese patients is significantly less than in lean patients during general anesthesia. However, it remains unknown whether reduced intraoperative tissue oxygenation in obese patients results from obesity per se or from a combination of anesthesia and surgery. In a pilot study, we tested the hypothesis that tissue oxygenation is reduced in spontaneously breathing, unanesthetized obese volunteers. Seven lean volunteers with a body mass index (BMI) of 22 +/- 2 kg/m(2) were compared to seven volunteers with a BMI of 46 +/- 4 kg/m(2). Volunteers were subjected to the following oxygen challenges: (1) room air; (2) 2 l/min oxygen via nasal prongs, (3) 6 l/min oxygen through a rebreathing face mask; (4) oxygen as needed to achieve an arterial oxygen pressure (arterial pO(2)) of 200 mmHg; and (5) oxygen as needed to achieve an arterial pO(2) of 300 mmHg. The oxygen challenges were randomized. Arterial pO(2) was measured with a continuous intraarterial blood gas analyzer (Paratrend 7); deltoid subcutaneous tissue oxygenation was measured with a polarographic microoxygen sensor (Licox). Subcutaneous tissue oxygenation was similar in lean and obese volunteers: (1) room air, 52 +/- 10 vs 58 +/- 8 mmHg; (2) 2 l/min, 77 +/- 25 vs 79 +/- 24 mmHg; (3) 6 l/min, 125 +/- 43 vs 121 +/- 25 mmHg; (4) arterial pO(2) = 200 mmHg, 115 +/- 42 vs 144 +/- 23 mmHg; (5) arterial pO(2) = 300 mmHg, 145 +/- 41 vs 154 +/- 32 mmHg. In this pilot study, we could not identify significant differences in deltoid subcutaneous tissue oxygen pressure between lean and morbidly obese volunteers.

Validation of the i-STAT and HemoCue systems for the analysis of blood parameters in the bar-headed goose, Anser indicus

PubMed Central

Harter, T. S.; Reichert, M.; Brauner, C. J.; Milsom, W. K.

2015-01-01

Every year, bar-headed geese (Anser indicus) perform some of the most remarkable trans-Himalayan migrations, and researchers are increasingly interested in understanding the physiology underlying their high-altitude flight performance. A major challenge is generating reliable measurements of blood parameters on wild birds in the field, where established analytical techniques are often not available. Therefore, we validated two commonly used portable clinical analysers (PCAs), the i-STAT and the HemoCue systems, for the analysis of blood parameters in bar-headed geese. The pH, partial pressures of O2 and CO2 (PO2 and PCO2), haemoglobin O2 saturation (sO2), haematocrit (Hct) and haemoglobin concentration [Hb] were simultaneously measured with the two PCA systems (i-STAT for all parameters; HemoCue for [Hb]) and with conventional laboratory techniques over a physiological range of PO2, PCO2 and Hct. Our results indicate that the i-STAT system can generate reliable values on bar-headed goose whole blood pH, PO2, PCO2 and Hct, but we recommend correcting the obtained values using the linear equations determined here for higher accuracy. The i-STAT is probably not able to produce meaningful measurements of sO2 and [Hb] over a range of physiologically relevant environmental conditions. However, we can recommend the use of the HemoCue to measure [Hb] in the bar-headed goose, if results are corrected. We emphasize that the equations that we provide to correct PCA results are applicable only to bar-headed goose whole blood under the conditions that we tested. We encourage researchers to validate i-STAT or HemoCue results thoroughly for their specific study conditions and species in order to yield accurate results. PMID:27293706

Pilot Assessment of the Repeatability of Indocyanine Green Fluorescence Imaging and Correlation with Traditional Foot Perfusion Assessments.

PubMed

Venermo, M; Settembre, N; Albäck, A; Vikatmaa, P; Aho, P-S; Lepäntalo, M; Inoue, Y; Terasaki, H

2016-10-01

Ankle brachial index (ABI), toe pressures (TP), and transcutaneous oxygen pressure (TcPO 2 ) are traditionally used in the assessment of critical limb ischemia (CLI). Indocyanine green (ICG) fluorescence imaging can be used to evaluate local circulation in the foot and to evaluate the severity of ischemia. This prospective study analyzed the suitability of a fluorescence imaging system (photodynamic eye [PDE]) in CLI. Forty-one patients with CLI were included. Of the patients, 66% had diabetes and there was an ischemic tissue lesion in 70% of the limbs. ABI, toe pressures, TcPO 2 and ICG-fluorescence imaging (ICG-FI) were measured in each leg. To study the repeatability of the ICG-FI, each patient underwent the study twice. After the procedure, foot circulation was measured using a time-intensity curve, where T1/2 (the time needed to achieve half of the maximum fluorescence intensity) and PDE10 (increase of the intensity during the first 10 s) were determined. A time-intensity curve was plotted using the same areas as for the TcPO 2 probes (n=123). The mean ABI was 0.43, TP 21 mmHg, TcPO 2 23 mmHg, T1/2 38 s, and PDE10 19 AU. Time-intensity curves were repeatable. In a Bland-Altman scatter plot, the 95% limits of agreement of PDE10 was 9.9 AU and the corresponding value of T1/2 was 14 s. Correlation between ABI and TP was significant (R=.73, p<.001), and it was weaker in diabetic patients (R=.47, p=.048) compared with non-diabetic patients (R=.89, p=.002). Correlations between ABI and TcPO 2 and TP and TcPO 2 were weak (R=.37, p=.05 and R=.43, p=.037, respectively). Correlation between TcPO 2 and PDE10 was strong in diabetic patients (R=.70, p=.003). According to this pilot study, ICG-FI with PDE can be used in the assessment of blood supply in the ischemic foot. Copyright © 2016 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Oxygen uptake and local Po2 profiles in submerged larvae of phaeoxantha klugii (Coleoptera: Cicindelidae), as well as their metabolic rate in air.

PubMed

Zerm, M; Zinkler, D; Adis, J

2004-01-01

We studied whether oxygen uptake from the surrounding water might enhance survival in submerged third instar larvae of Phaeoxantha klugii, a tiger beetle from the central Amazonian floodplains. Local oxygen partial pressures (Po(2)) were measured with microcoaxial needle electrodes close to larvae submerged in initially air-saturated still water. The Po(2) profiles showed that the larvae exploit oxygen from the aquatic medium. Metabolism in the air of more or less resting larvae was determined by measuring the rate of CO(2) production (sV dot co2) with an infrared gas analyzer at 29 degrees C. The sV dot co2 was around 1.8 mu L g(-1) min(-1), equivalent to an oxygen consumption rate (sV dot o2) of 1.8-2.6 mu L g(-1) min(-1). Oxygen consumption (V dot o2) of individually submerged larvae measured in closed respiration chambers at 19-10.3 kPa Po(2) (initially air saturated, 29 degrees C) ranged between 0.05 and 0.2 mu L min(-1) and was not correlated with body mass. The sV dot o2 ranged between 0.1 and 0.4 mu L min(-1), that is, 4%-22% of the metabolic rate measured in air. Mean V dot o2 decreased with declining Po(2); however, some individuals showed contrary patterns. V dot o2 was additionally measured in dormant larvae, in larvae submerged for 1-2 d in open water or for 30-49 d within sediment, as well as in larvae exposed to anoxia before the measurements. The range of V dot o2 was similar in all groups, indicating that the larvae exploit oxygen from the water whenever available. Similar V dot o2 across the whole range of body mass investigated (0.31-0.76 g) suggests that oxygen uptake occurs by spiracular uptake. Assuming that larvae survive for some time at rates comparable to depressed metabolic rates reported for other insect species, it can be concluded that oxygen uptake from water can sustain aerobic metabolism even under quite severe hypoxia. It might therefore play an important role for survival during inundation periods.

Neuroprotective effects of angiotensin II type 1 receptor (AT1-R) blocker via modulating AT1-R signaling and decreased extracellular glutamate levels.

PubMed

Fujita, Tomoyoshi; Hirooka, Kazuyuki; Nakamura, Takehiro; Itano, Toshifumi; Nishiyama, Akira; Nagai, Yukiko; Shiraga, Fumio

2012-06-26

To investigate the mechanism of the neuroprotective effects of the angiotensin II type 1 receptor (AT1-R) blocker against retinal ischemia-reperfusion injury in the rat. Retinal ischemia was induced by increasing intraocular pressure. Glutamate release from the rat retina and intravitreal PO(2) (partial pressure of oxygen) profiles were monitored during and after ischemia using a microdialysis biosensor and oxygen-sensitive microelectrodes. ELISA was used to measure changes in the expression of AT1-R. Retinal mRNA expressions of p47phox and p67phox were measured by real-time polymerase chain reaction. Reactive oxygen species (ROS) were measured using dihydroethidium. Administration of candesartan, which is an AT1-R blocker (ARB), suppressed ischemia-induced increases in the extracellular glutamate. Candesartan also attenuated the increase in intravitreal PO(2) during reperfusion. AT1-R expression peaked at 12 hours after reperfusion. Although there was an increase in the retinal mRNA expression of p47phox and p64phox at 12 hours after the reperfusion, administration of candesartan suppressed these expressions. The production of ROS that was detected at 12 hours after reperfusion was also suppressed by the administration of candesartan or apocynin. NADPH oxidase-mediated ROS production increased at 12 hours after reperfusion. Candesartan may protect neurons by decreasing extracellular glutamate immediately after reperfusion and by attenuating oxidative stress via a modulation of the AT1-R signaling that occurs during ischemic insult.

Mathematical Model of an Innate Immune Response to Cutaneous Wound in the Presence of Local Hypoxia.

PubMed

Saiko, Guennadi; Cross, Karen; Douplik, Alexandre

We developed a 2D multi-agent stochastic model of interaction between cellular debris, bacteria and neutrophils in the surface cutaneous wound with local hypoxia. Bacteria, which grow logistically with a maximum carrying capacity, and debris are phagocytosed by neutrophils with probability determined by the partial pressure of oxygen in the tissue, pO 2  = 4-400 mmHg, according to the Michaelis-Menten equation with K m  = 40 mmHg. The influx of new neutrophils depends linearly (k = 0.05-0.2) on the amount of (a) platelets and (b) neutrophils, which are in contact with bacteria or debris. Each activated neutrophil can accomplish a certain amount of phagocytosis, n max  = 5-20, during its lifespan, T = 1-5 days. The universe of outcomes consists of (a) bacteria clearance (high k and n max ), (b) infection is not cleared by neutrophils (low k and nmax), and (c) intermittent (quasiperiodic) bursts of inflammation. In the absence of infection, phagocytosis stops within 48 h. We found that pO 2 alone did not change the type of outcome, but affects the number of recruited neutrophils and inflammation duration (in the absence of infection by up to 10 and 5 %, respectively).

Impact of oxygen chemistry on the emission and fluorescence spectroscopy of laser ablation plumes

NASA Astrophysics Data System (ADS)

Hartig, K. C.; Brumfield, B. E.; Phillips, M. C.; Harilal, S. S.

2017-09-01

Oxygen present in the ambient gas medium may affect both laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) emission through a reduction of emission intensity and persistence. In this study, an evaluation is made on the role of oxygen in the ambient environment under atmospheric pressure conditions in LIBS and laser ablation (LA)-LIF emission. To generate plasmas, 1064 nm, 10 ns pulses were focused on an aluminum alloy sample. LIF was performed by frequency scanning a CW laser over the 396.15 nm (3s24s 2S1/2 → 3s23p 2P°3/2) Al I transition. Time-resolved emission and fluorescence signals were recorded to evaluate the variation in emission intensity caused by the presence of oxygen. The oxygen partial pressure (po) in the atmospheric pressure environment using N2 as the makeup gas was varied from 0 to 400 Torr O2. 2D-fluorescence spectroscopy images were obtained for various oxygen concentrations for simultaneous evaluation of the emission and excitation spectral features. Results showed that the presence of oxygen in the ambient environment reduces the persistence of the LIBS and LIF emission through an oxidation process that depletes the density of atomic species within the resulting laser-produced plasma (LPP) plume.

Air travel and adults with cyanotic congenital heart disease.

PubMed

Harinck, E; Hutter, P A; Hoorntje, T M; Simons, M; Benatar, A A; Fischer, J C; de Bruijn, D; Meijboom, E J

1996-01-15

Concern has been expressed that a reduction of partial oxygen pressure during flight in commercial aircraft may induce dangerous hypoxemia in patients with cyanotic congenital heart disease. To evaluate the validity of this concern, the transcutaneous SaO2 was measured in 12 adults with this type of heart disease and 27 control subjects during simulated commercial flights of 1.5 and 7 hours in a hypobaric chamber. Ten of those patients and 6 control subjects also were evaluated during two actual flights of approximately 2.5 hours in a DC-10 and an A-310, respectively. During the prolonged simulated and actual flights, the capillary blood pH, gases, and lactic acid were analyzed in the patients and during one of the actual flights also in the control subjects. During the simulated flights the SaO2 was at all times lower in the patients than in the control subjects. However, the maximal mean actual percentage decrease, as compared with sea level values, did not exceed 8.8% in either patients or control subjects. During the actual flights, this maximal decrease in the patients was 6%. In-flight reduction of the capillary PO2 was considerable in the control subjects but not in the patients. It is our hypothesis that the lack of a significant decrease of the PO2 in the patients might possibly be due to a high concentration of 2.3 diphosphoglycerate in the red cells. The flights had no influence on the capillary blood pH, PCO2, bicarbonate, or lactic acid levels in either patients or control subjects. Atmospheric pressure changes during commercial air travel do not appear to be detrimental to patients with cyanotic congenital heart disease.

Super, Red Palm and Palm Oleins Improve the Blood Pressure, Heart Size, Aortic Media Thickness and Lipid Profile in Spontaneously Hypertensive Rats

PubMed Central

Boon, Chee-Meng; Ng, Mei-Han; Choo, Yuen-May; Mok, Shiueh-Lian

2013-01-01

Background Oleic acid has been shown to lower high blood pressure and provide cardiovascular protection. Curiosity arises as to whether super olein (SO), red palm olein (RPO) and palm olein (PO), which have high oleic acid content, are able to prevent the development of hypertension. Methodology/Principal Findings Four-week-old male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were fed 15% SO, RPO or PO supplemented diet for 15 weeks. After 15 weeks of treatment, the systolic blood pressure (SBP) of SHR treated with SO, RPO and PO were 158.4±5.0 mmHg (p<0.001), 178.9±2.7 mmHg (p<0.001) and 167.7±2.1 mmHg (p<0.001), respectively, compared with SHR controls (220.9±1.5 mmHg). Bradycardia was observed with SO and PO. In contrast, the SBP and heart rate of treated WKY rats were not different from those of WKY controls. The SO and PO significantly reduced the increased heart size and thoracic aortic media thickness observed in untreated SHR but RPO reduced only the latter. No such differences, however, were observed between the treated and untreated WKY rats. Oil Red O enface staining of thoracic-abdominal aorta did not show any lipid deposition in all treated rats. The SO and RPO significantly raised serum alkaline phosphatase levels in the SHR while body weight and renal biochemical indices were unaltered in both strains. Serum lipid profiles of treated SHR and WKY rats were unchanged, with the exception of a significant reduction in LDL-C level and total cholesterol/HDL ratio (atherogenic index) in SO and RPO treated SHR compared with untreated SHR. Conclusion The SO, RPO and PO attenuate the rise in blood pressure in SHR, accompanied by bradycardia and heart size reduction with SO and PO, and aortic media thickness reduction with SO, RPO and PO. The SO and RPO are antiatherogenic in nature by improving blood lipid profiles in SHR. PMID:23409085

Protonic Conductors for Intermediate Temperature Fuel Cell Electrolytes: Superprotonic CsH2PO4 Stabilization and in-Doped SnP2O7 Structure Study

NASA Astrophysics Data System (ADS)

Martinez Salinas, Heber Jair

Proton conductor solid electrolytes CsH2PO4 and In-doped tin pyrophosphate have been investigated as candidates to fill a gap of suitable electrolytes for fuel cells at the intermediate temperature range due their unusually high conductivities between 200 and 300 °C. Unfortunately, in the case of CsH2PO4, complicated experimental conditions, like a humidified environment, or high pressure, are needed to preserve the sought high conducting phase. In the first stage of this work, X-ray diffraction on CsH2PO 4 samples performed in air, and under normal conditions of humidity and pressure, evidence of the cubic phase of CsH2PO4 was observed during short intervals of temperature and time, starting at 215 °C and disappearing completely at 265 °C into a dehydrated phase. An AC impedance spectroscopy experimental setup has been assembled and data has been successfully collected on undoped, and doped CsH2PO 4 samples to investigate the effects of chemical and environmental modifications. Measurements performed in the temperature range 200 - 260 °C, and using the frequency range 1 - 6 MHz, showed that the high conducting phase of undoped CsH2PO4 was present for a very short interval of temperature. Additionally, these measurements showed that nano-silica-doped CsH2PO4, and CsH2PO4 under a humidified environment achieve the highest values of conductivity, above 10-2 S cm-1 among the samples tested. In the second stage of this investigation, AC impedance spectroscopy measurements were successfully performed on CsH2PO4 samples in air, at temperatures from 200 - 260 °C, and in the frequency range 1 - 6 MHz, inside a hermetically sealed stainless-steel chamber, which was designed and assembled in-house. Results showed that the highly conducting phase of CsH2PO 4 was achieved at temperatures measured above 230 °C, reaching conductivity values up to 1.7 x10-2 S cm-1, and remaining stable for over 40 hours. Consequent X-ray diffraction analysis of such samples showed that a monoclinic structure, characteristic of room temperature CsH 2PO4, was the only phase present even after the samples had been heated for over 40 hours at a temperature of 250 °C. By using this novel contraption, this has been the first time that undoped CsH2PO 4 has achieved its high conductivity phase and maintained a stable conductivity for a significant amount of time in air, without the use of a humidified environment, and without high pressure in an AC impedance spectroscopy study. Finally, in-house and synchrotron X-ray diffraction studies performed in the Sn1-xInxP2O7 series showed the cubic structure characteristic of the undoped compound at room temperature remains present up to temperatures of 250 °C. Sn0.9In 0.1P2O7, which is known to have the highest conductivity of the compound series, presented an increased unit cell as compared to the rest of the series when measured in air. However, the increased unit cell was not observed when measured under vacuum or an inert gas. Doping did not produce any major distortions on the P2O7 tetrahedra.

Early history of high-altitude physiology.

PubMed

West, John B

2016-02-01

High-altitude physiology can be said to have begun in 1644 when Torricelli described the first mercury barometer and wrote the immortal words "We live submerged at the bottom of an ocean of the element air." Interestingly, the notion of atmospheric pressure had eluded his teacher, the great Galileo. Blaise Pascal was responsible for describing the fall in pressure with increasing altitude, and Otto von Guericke gave a dramatic demonstration of the enormous force that could be developed by atmospheric pressure. Robert Boyle learned of Guericke's experiment and, with Robert Hooke, constructed the first air pump that allowed small animals to be exposed to a low pressure. Hooke also constructed a small low-pressure chamber and exposed himself to a simulated altitude of about 2400 meters. With the advent of ballooning, humans were rapidly exposed to very low pressures, sometimes with tragic results. For example, the French balloon, Zénith, rose to over 8000 m, and two of the three aeronauts succumbed to the hypoxia. Paul Bert was the first person to clearly state that the deleterious effects of high altitude were caused by the low partial pressure of oxygen (PO2), and later research was accelerated by high-altitude stations and expeditions to high altitude. © 2015 New York Academy of Sciences.

Complete genome analysis of porcine kobuviruses from the feces of pigs in Japan.

PubMed

Akagami, Masataka; Ito, Mika; Niira, Kazutaka; Kuroda, Moegi; Masuda, Tsuneyuki; Haga, Kei; Tsuchiaka, Shinobu; Naoi, Yuki; Kishimoto, Mai; Sano, Kaori; Omatsu, Tsutomu; Aoki, Hiroshi; Katayama, Yukie; Oba, Mami; Oka, Tomoichiro; Ichimaru, Toru; Yamasato, Hiroshi; Ouchi, Yoshinao; Shirai, Junsuke; Katayama, Kazuhiko; Mizutani, Tetsuya; Nagai, Makoto

2017-08-01

Porcine kobuviruses (PoKoVs) are ubiquitously distributed in pig populations worldwide and are thought to be enteric viruses in swine. Although PoKoVs have been detected in pigs in Japan, no complete genome data for Japanese PoKoVs are available. In the present study, 24 nearly complete or complete sequences of the PoKoV genome obtained from 10 diarrheic feces and 14 non-diarrheic feces of Japanese pigs were analyzed using a metagenomics approach. Japanese PoKoVs shared 85.2-100% identity with the complete coding nucleotide (nt) sequences and the closest relationship of 85.1-98.3% with PoKoVs from other countries. Twenty of 24 Japanese PoKoVs carried a deletion of 90 nt in the 2B coding region. Phylogenetic tree analyses revealed that PoKoVs were not grouped according to their geographical region of origin and the phylogenetic trees of the L, P1, P2, and P3 genetic regions showed topologies different from each other. Similarity plot analysis using strains from a single farm revealed partially different similarity patterns among strains from identical farm origins, suggesting that recombination events had occurred. These results indicate that various PoKoV strains are prevalent and not restricted geographically on pig farms worldwide and the coexistence of multiple strains leads to recombination events of PoKoVs and contributes to the genetic diversity and evolution of PoKoVs.

Brain parenchyma PO2, PCO2, and pH during and after hypoxic, ischemic brain insult in dogs.

PubMed

McKinley, B A; Morris, W P; Parmley, C L; Butler, B D

1996-11-01

1) The investigation of fiberoptic PO2, PCO2, and pH sensor technology as a monitor of brain parenchyma during and after brain injury, and 2) the comparison of brain parenchyma PO2, PCO2, and pH with intracranial pressure during and after hypoxic, ischemic brain insult. Prospective, controlled, animal study in an acute experimental preparation. Physiology laboratory in a university medical school. Fourteen mongrel dogs (20 to 35 kg), anesthetized, room-air ventilated. Anesthesia was induced with thiopental and maintained after intubation using 1% to 1.5% halothane in room air (FiO2 0.21). Mechanical ventilation was established to maintain end-tidal PCO2 approximately 35 torr (-4.7 kPa). Intravenous, femoral artery, and pulmonary artery catheters were placed. The common carotid arteries were surgically exposed, and ultrasonic blood flow probes were applied. A calibrated intracranial pressure probe was placed through a right-side transcranial bolt, and a calibrated intracranial chemistry probe with optical sensors for PO2, PCO2, and pH was placed through a left-side bolt into brain parenchyma. Brain insult was induced in the experimental group (n = 6) by hypoxia (FiO2 0.1), ischemia (bilateral carotid artery occlusion), and hypotension (mean arterial pressure [MAP] approximately 40 mm Hg produced with isoflurane approximately 4%). After 45 mins, carotid artery occlusion was released, FiO2 was reset to 0.21, and anesthetic was returned to halothane (approximately 1.25%). The control group (n = 5) had the same surgical preparation and sequence of anesthetic agent exposure but no brain insult. Monitored variables included brain parenchyma PO2, PCO2, and pH, which were monitored at 1-min intervals, and intracranial pressure, MAP, arterial hemoglobin oxygen saturation (by pulse oximetry), end-tidal PCO2, and carotid artery blood flow rate, for which data were collected at 15-min intervals for 7 hrs. Arterial and mixed venous blood gas analyses were done at approximately 1-hr intervals. Baseline data agreed closely with other published results: brain parenchyma PO2 of 27 +/- 7 (SD) torr (3.6 +/- 0.9 kPa); brain parenchyma PCO2 of 69 +/- 12 torr (9.2 +/- 1.6 kPa); and brain parenchyma pH of 7.13 +/- 0.09. Postcalibration data were accurate, indicating stability and durability over several hours. In six experiments, during the brain insult, brain parenchyma PO2 decreased to 16 +/- 2 torr (2.1 +/- 0.3 kPa), brain parenchyma PCO2 increased to 105 +/- 44 torr (14 +/- 5.9 kPa) (p < .05), and brain parenchyma pH decreased to 6.75 +/- 0.08 (p < .05). Intracranial pressure (ICP) remained nearly constant (baseline 16 +/- 6 to 14 +/- 5 mm Hg at the end of the brain insult). Cerebral perfusion pressure (CPP = MAP - ICP) decreased (baseline 95 +/- 15 to 28 +/- 8 mm Hg; p < .05). On release of brain insult stresses, ICP increased to 30 +/- 9 mm Hg and CPP increased to 71 +/- 19 mm Hg (p < .05). A biphasic recovery was observed for brain parenchyma pH, which had the slowest recovery of the monitored variables. On average, brain parenchyma pH gradually returned toward baseline, and was no longer significantly different from baseline 3 hrs after release of insult stresses. Brain parenchyma PCO2 continued to decrease rapidly after brain insult and then remained approximately 52 +/- 10 torr (approximately 6.9 +/- 1.3 kPa) (p < .05). Brain parenchyma PO2 increased from a minimum at the end of brain insult to a maximum of 43 +/- 17 torr (5.7 +/- 2.3 kPa) within 1.25 hrs (p < .05), and then gradually decreased to approximately 35 +/- 10 torr (approximately 4.7 +/- 1.3 kPa). Cerebral perfusion pressure gradually decreased as ICP increased 3 to 5 hrs after insult. Intracranial chemistry probes with optical sensors demonstrated stable, reproducible monitoring of brain parenchyma PO2, PCO2, and pH in dogs for periods lasting > 8 hrs. Significant changes in brain p

Surprising luminescent properties of the polyphosphates Ln(PO3)3:Eu (Ln = Y, Gd, Lu).

PubMed

Höppe, Henning A; Kazmierczak, Karolina; Kacprzak, Sylwia; Schellenberg, Inga; Pöttgen, Rainer

2011-10-21

The optical emission properties of the lanthanoid catena-polyphosphates Ln(PO(3))(3) (Ln = Y, Gd, Lu) doped with europium were investigated. Incommensurately modulated β-Y(PO(3))(3):Eu (super space group Cc (0|0.364|0)0) and Gd(PO(3))(3):Eu (space group I2/a) show the usual emission characteristics of Eu(3+), while in Lu(PO(3))(3):Eu (space group Cc) the europium is unprecedentedly partially reduced to the divalent state, as proven by both a broad emission band at 406 nm excited at 279 nm and an EPR spectroscopic investigation. (151)Eu-Mössbauer spectroscopy showed that only a very small part of the europium is reduced in Lu(PO(3))(3):Eu. An explanation for this unusual behaviour is given. This journal is © The Royal Society of Chemistry 2011

Direct effects of manganese compounds on dopamine and its metabolite Dopac: an in vitro study

PubMed Central

Sistrunk, Shannon C.; Ross, Matthew K.; Filipov, Nikolay M.

2007-01-01

Following combustion of fuel containing the additive methylcyclopentadienyl-manganese-tricarbonyl (MMT), manganese phosphate (MnPO4) and manganese sulfate (MnSO4) are emitted in the atmosphere. Manganese chloride (MnCl2), another Mn2+ species, is widely used experimentally. Using rat striatal slices, we found that MnPO4 decreased tissue and media dopamine (DA) and media Dopac (a DA metabolite) levels substantially more than either MnCl2 or MnSO4; antioxidants were partially protective. Also, both MnCl2 and MnPO4 (more potently) oxidized DA and Dopac even in the absence of tissue in the media, suggesting a direct interaction between Mn and DA/Dopac. Because aminochrome is a major oxidation product of DA, we next determined whether MnPO4 will be more potent in forming aminochrome than MnCl2 or MnSO4 which, indeed, was the case. Thus, a potential additional mechanism for the neurotoxic effects of environmentally-relevant forms of Mn, MnPO4 in particular, is the generation of reactive DA intermediates. PMID:18449324

DFT computational study on the phosphate functionalized SWCNTs as efficient drug delivery systems for anti-osteoporosis zolendronate and risedronate drugs

NASA Astrophysics Data System (ADS)

Nikfar, Zahra; Shariatinia, Zahra

2017-07-01

The pristine (4,4)-armchair SWCNT as well as its three phosphate functionalized (CNT-nH2PO4, n=1-3) forms were studied as novel drug delivery systems for the two commercially famous anti-osteoporosis drugs including risedronate (RIS) and zolendronate (ZOL) using the density functional theory (DFT) computations at both B3LYP and B3PW91 levels. Results revealed that the binding energy was increased by increasing number of H2PO4 moieties attached on the CNT with the most negative binding energy was measured for the CNT-3H2PO4 carrier. The dipole moments of all phosphate containing CNTs were much greater ( 1.5-4.5 D) than that of pristine CNT ( 0 D). The contour maps verified that when the CNT was functionalized by H2PO4 groups, the symmetric distribution of electric charge was vanished so that the highest and the lowest asymmetric charge distributions were achieved for the CNT-2H2PO4 and CNT-3H2PO4, respectively, leading to the greatest and the smallest dipole moments for the CNT-2H2PO4 (4.177 D) and the CNT-3H2PO4 (1.614 D). The compounds RIS-CNT-3H2PO4 and ZOL-CNT-3H2PO4 displayed the greatest electronegativity and electrophilicity index which were appropriate for the binding of drugs onto the bone surface (having partial positive charge due to the presence of Ca2+) and therefore effectively inhibiting the osteoporosis. Consequently, it was proposed that the drug-CNT-3H2PO4 was the most appropriate drug-carrier system for both of the RIS and ZOL drugs which could be employed as the most efficient vehicle.

The NO donor sodium nitroprusside: evaluation of skeletal muscle vascular and metabolic dysfunction

PubMed Central

Hirai, Daniel M.; Copp, Steven W.; Ferguson, Scott K.; Holdsworth, Clark T.; Musch, Timothy I.; Poole, David C.

2012-01-01

The nitric oxide (NO) donor sodium nitroprusside (SNP) may promote cyanide-induced toxicity and systemic and/or local responses approaching maximal vasodilation. The hypotheses were tested that SNP superfusion of the rat spinotrapezius muscle exerts 1) residual impairments in resting and contracting blood flow, oxygen utilization (V̇O2) and microvascular O2 pressure (PO2mv); and 2) marked hypotension and elevation in resting PO2mv. Two superfusion protocols were performed: 1) Krebs-Henseleit (control 1), SNP (300 µM; a dose used commonly in superfusion studies) and Krebs-Henseleit (control 2), in this order; 2) 300 and 1200 µM SNP in random order. Spinotrapezius muscle blood flow (radiolabeled microspheres), V̇O2 (Fick calculation) and PO2mv (phosphorescence quenching) were determined at rest and during electrically-induced (1 Hz) contractions. There were no differences in spinotrapezius blood flow, V̇O2 or PO2mv at rest and during contractions pre- and post-SNP condition (control 1 and control 2; p>0.05 for all). With regard to dosing, SNP produced a graded elevation in resting PO2mv (p<0.05) with a reduction in mean arterial pressure only at the higher concentration (p<0.05). Contrary to our hypothesis, skeletal muscle superfusion with the NO donor SNP (300 µM) improved microvascular oxygenation during the transition from rest to contractions (PO2mv kinetics) without precipitating residual impairment of muscle hemodynamic or metabolic control or compromising systemic hemodynamics. These data suggest that SNP superfusion (300 µM) constitutes a valid and important tool for assessing the functional roles of NO in resting and contracting skeletal muscle function without incurring residual alterations consistent with cyanide accumulation and poisoning. PMID:23174313

Computational Model for Oxygen Transport and Consumption in Human Vitreous

PubMed Central

Filas, Benjamen A.; Shui, Ying-Bo; Beebe, David C.

2013-01-01

Purpose. Previous studies that measured liquefaction and oxygen content in human vitreous suggested that exposure of the lens to excess oxygen causes nuclear cataracts. Here, we developed a computational model that reproduced available experimental oxygen distributions for intact and degraded human vitreous in physiologic and environmentally perturbed conditions. After validation, the model was used to estimate how age-related changes in vitreous physiology and structure alter oxygen levels at the lens. Methods. A finite-element model for oxygen transport and consumption in the human vitreous was created. Major inputs included ascorbate-mediated oxygen consumption in the vitreous, consumption at the posterior lens surface, and inflow from the retinal vasculature. Concentration-dependent relations were determined from experimental human data or estimated from animal studies, with the impact of all assumptions explored via parameter studies. Results. The model reproduced experimental data in humans, including oxygen partial pressure (Po2) gradients (≈15 mm Hg) across the anterior-posterior extent of the vitreous body, higher oxygen levels at the pars plana relative to the vitreous core, increases in Po2 near the lens after cataract surgery, and equilibration in the vitreous chamber following vitrectomy. Loss of the antioxidative capacity of ascorbate increases oxygen levels 3-fold at the lens surface. Homogeneous vitreous degeneration (liquefaction), but not partial posterior vitreous detachment, greatly increases oxygen exposure to the lens. Conclusions. Ascorbate content and the structure of the vitreous gel are critical determinants of lens oxygen exposure. Minimally invasive surgery and restoration of vitreous structure warrant further attention as strategies for preventing nuclear cataracts. PMID:24008409

Computational model for oxygen transport and consumption in human vitreous.

PubMed

Filas, Benjamen A; Shui, Ying-Bo; Beebe, David C

2013-10-15

Previous studies that measured liquefaction and oxygen content in human vitreous suggested that exposure of the lens to excess oxygen causes nuclear cataracts. Here, we developed a computational model that reproduced available experimental oxygen distributions for intact and degraded human vitreous in physiologic and environmentally perturbed conditions. After validation, the model was used to estimate how age-related changes in vitreous physiology and structure alter oxygen levels at the lens. A finite-element model for oxygen transport and consumption in the human vitreous was created. Major inputs included ascorbate-mediated oxygen consumption in the vitreous, consumption at the posterior lens surface, and inflow from the retinal vasculature. Concentration-dependent relations were determined from experimental human data or estimated from animal studies, with the impact of all assumptions explored via parameter studies. The model reproduced experimental data in humans, including oxygen partial pressure (Po2) gradients (≈15 mm Hg) across the anterior-posterior extent of the vitreous body, higher oxygen levels at the pars plana relative to the vitreous core, increases in Po2 near the lens after cataract surgery, and equilibration in the vitreous chamber following vitrectomy. Loss of the antioxidative capacity of ascorbate increases oxygen levels 3-fold at the lens surface. Homogeneous vitreous degeneration (liquefaction), but not partial posterior vitreous detachment, greatly increases oxygen exposure to the lens. Ascorbate content and the structure of the vitreous gel are critical determinants of lens oxygen exposure. Minimally invasive surgery and restoration of vitreous structure warrant further attention as strategies for preventing nuclear cataracts.

Suppression of shrimp melanization during white spot syndrome virus infection.

PubMed

Sutthangkul, Jantiwan; Amparyup, Piti; Charoensapsri, Walaiporn; Senapin, Saengchan; Phiwsaiya, Kornsunee; Tassanakajon, Anchalee

2015-03-06

The melanization cascade, activated by the prophenoloxidase (proPO) system, plays a key role in the production of cytotoxic intermediates, as well as melanin products for microbial sequestration in invertebrates. Here, we show that the proPO system is an important component of the Penaeus monodon shrimp immune defense toward a major viral pathogen, white spot syndrome virus (WSSV). Gene silencing of PmproPO(s) resulted in increased cumulative shrimp mortality after WSSV infection, whereas incubation of WSSV with an in vitro melanization reaction prior to injection into shrimp significantly increased the shrimp survival rate. The hemolymph phenoloxidase (PO) activity of WSSV-infected shrimp was extremely reduced at days 2 and 3 post-injection compared with uninfected shrimp but was fully restored after the addition of exogenous trypsin, suggesting that WSSV probably inhibits the activity of some proteinases in the proPO cascade. Using yeast two-hybrid screening and co-immunoprecipitation assays, the viral protein WSSV453 was found to interact with the proPO-activating enzyme 2 (PmPPAE2) of P. monodon. Gene silencing of WSSV453 showed a significant increase of PO activity in WSSV-infected shrimp, whereas co-silencing of WSSV453 and PmPPAE2 did not, suggesting that silencing of WSSV453 partially restored the PO activity via PmPPAE2 in WSSV-infected shrimp. Moreover, the activation of PO activity in shrimp plasma by PmPPAE2 was significantly decreased by preincubation with recombinant WSSV453. These results suggest that the inhibition of the shrimp proPO system by WSSV partly occurs via the PmPPAE2-inhibiting activity of WSSV453. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Suppression of Shrimp Melanization during White Spot Syndrome Virus Infection*

PubMed Central

Sutthangkul, Jantiwan; Amparyup, Piti; Charoensapsri, Walaiporn; Senapin, Saengchan; Phiwsaiya, Kornsunee; Tassanakajon, Anchalee

2015-01-01

The melanization cascade, activated by the prophenoloxidase (proPO) system, plays a key role in the production of cytotoxic intermediates, as well as melanin products for microbial sequestration in invertebrates. Here, we show that the proPO system is an important component of the Penaeus monodon shrimp immune defense toward a major viral pathogen, white spot syndrome virus (WSSV). Gene silencing of PmproPO(s) resulted in increased cumulative shrimp mortality after WSSV infection, whereas incubation of WSSV with an in vitro melanization reaction prior to injection into shrimp significantly increased the shrimp survival rate. The hemolymph phenoloxidase (PO) activity of WSSV-infected shrimp was extremely reduced at days 2 and 3 post-injection compared with uninfected shrimp but was fully restored after the addition of exogenous trypsin, suggesting that WSSV probably inhibits the activity of some proteinases in the proPO cascade. Using yeast two-hybrid screening and co-immunoprecipitation assays, the viral protein WSSV453 was found to interact with the proPO-activating enzyme 2 (PmPPAE2) of P. monodon. Gene silencing of WSSV453 showed a significant increase of PO activity in WSSV-infected shrimp, whereas co-silencing of WSSV453 and PmPPAE2 did not, suggesting that silencing of WSSV453 partially restored the PO activity via PmPPAE2 in WSSV-infected shrimp. Moreover, the activation of PO activity in shrimp plasma by PmPPAE2 was significantly decreased by preincubation with recombinant WSSV453. These results suggest that the inhibition of the shrimp proPO system by WSSV partly occurs via the PmPPAE2-inhibiting activity of WSSV453. PMID:25572398

Water deprivation-induced sodium appetite: humoral and cardiovascular mediators and immediate early genes

NASA Technical Reports Server (NTRS)

De Luca, Laurival A Jr; Xu, Zhice; Schoorlemmer, Guus H M.; Thunhorst, Robert L.; Beltz, Terry G.; Menani, Jose V.; Johnson, Alan Kim

2002-01-01

Adult rats deprived of water for 24-30 h were allowed to rehydrate by ingesting only water for 1-2 h. Rats were then given access to both water and 1.8% NaCl. This procedure induced a sodium appetite defined by the operational criteria of a significant increase in 1.8% NaCl intake (3.8 +/- 0.8 ml/2 h; n = 6). Expression of Fos (as assessed by immunohistochemistry) was increased in the organum vasculosum of the lamina terminalis (OVLT), median preoptic nucleus (MnPO), subfornical organ (SFO), and supraoptic nucleus (SON) after water deprivation. After rehydration with water but before consumption of 1.8% NaCl, Fos expression in the SON disappeared and was partially reduced in the OVLT and MnPO. However, Fos expression did not change in the SFO. Water deprivation also 1) increased plasma renin activity (PRA), osmolality, and plasma Na+; 2) decreased blood volume; and 3) reduced total body Na+; but 4) did not alter arterial blood pressure. Rehydration with water alone caused only plasma osmolality and plasma Na+ concentration to revert to euhydrated levels. The changes in Fos expression and PRA are consistent with a proposed role for ANG II in the control of the sodium appetite produced by water deprivation followed by rehydration with only water.

Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: kinetics and biodegradability enhancement.

PubMed

Suárez-Ojeda, María Eugenia; Kim, Jungkwon; Carrera, Julián; Metcalfe, Ian S; Font, Josep

2007-06-18

Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15 bar of oxygen partial pressure (P(O2)) and at 180, 200 and 220 degrees C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P(O2) were 140-160 degrees C and 2-9 bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160 degrees C and 2 bar of P(O2), which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD(RB)) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture.

Modelling the evaporation of a tear film over a contact lens.

PubMed

Talbott, Kevin; Xu, Amber; Anderson, Daniel M; Seshaiyer, Padmanabhan

2015-06-01

A contact lens (CL) separates the tear film into a pre-lens tear film (PrLTF), the fluid layer between the CL and the outside environment, and a post-lens tear film (PoLTF), the fluid layer between the CL and the cornea. We examine a model for evaporation of a PrLTF on a modern permeable CL allowing fluid transfer between the PrLTF and the PoLTF. Evaporation depletes the PrLTF, and continued evaporation causes depletion of the PoLTF via fluid loss through the CL. Governing equations include Navier-Stokes, heat and Darcy's equations for the fluid flow and heat transfer in the PrLTF and porous layer. The PoLTF is modelled by a fixed pressure condition on the posterior surface of the CL. The original model is simplified using lubrication theory for the PrLTF and CL applied to a sagittal plane through the eye. We obtain a partial differential equation (PDE) for the PrLTF thickness that is first-order in time and fourth-order in space. This model incorporates evaporation, conjoining pressure effects in the PrLTF, capillarity and heat transfer. For a planar film, we find that this PDE can be reduced to an ordinary differential equation (ODE) that can be solved analytically or numerically. This reduced model allows for interpretation of the various system parameters and captures most of the basic physics contained in the model. Comparisons of ODE and PDE models, including estimates for the loss of fluid through the lens due to evaporation, are given. © The Authors 2014. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

Time course of right ventricular pressure-overload induced myocardial fibrosis: relationship to changes in fibroblast postsynthetic procollagen processing.

PubMed

Baicu, Catalin F; Li, Jiayu; Zhang, Yuhua; Kasiganesan, Harinath; Cooper, George; Zile, Michael R; Bradshaw, Amy D

2012-11-01

Myocardial fibrillar collagen is considered an important determinant of increased ventricular stiffness in pressure-overload (PO)-induced cardiac hypertrophy. Chronic PO was created in feline right ventricles (RV) by pulmonary artery banding (PAB) to define the time course of changes in fibrillar collagen content after PO using a nonrodent model and to determine whether this time course was dependent on changes in fibroblast function. Total, soluble, and insoluble collagen (hydroxyproline), collagen volume fraction (CVF), and RV end-diastolic pressure were assessed 2 days and 1, 2, 4, and 10 wk following PAB. Fibroblast function was assessed by quantitating the product of postsynthetic processing, insoluble collagen, and levels of SPARC (secreted protein acidic and rich in cysteine), a protein that affects procollagen processing. RV hypertrophic growth was complete 2 wk after PAB. Changes in RV collagen content did not follow the same time course. Two weeks after PAB, there were elevations in total collagen (control RV: 8.84 ± 1.03 mg/g vs. 2-wk PAB: 11.50 ± 0.78 mg/g); however, increased insoluble fibrillar collagen, as measured by CVF, was not detected until 4 wk after PAB (control RV CVF: 1.39 ± 0.25% vs. 4-wk PAB: 4.18 ± 0.87%). RV end-diastolic pressure was unchanged at 2 wk, but increased until 4 wk after PAB. RV fibroblasts isolated after 2-wk PAB had no changes in either insoluble collagen or SPARC expression; however, increases in insoluble collagen and in levels of SPARC were detected in RV fibroblasts from 4-wk PAB. Therefore, the time course of PO-induced RV hypertrophy differs significantly from myocardial fibrosis and diastolic dysfunction. These temporal differences appear dependent on changes in fibroblast function.

Time course of right ventricular pressure-overload induced myocardial fibrosis: relationship to changes in fibroblast postsynthetic procollagen processing

PubMed Central

Baicu, Catalin F.; Li, Jiayu; Zhang, Yuhua; Kasiganesan, Harinath; Cooper, George; Zile, Michael R.

2012-01-01

Myocardial fibrillar collagen is considered an important determinant of increased ventricular stiffness in pressure-overload (PO)-induced cardiac hypertrophy. Chronic PO was created in feline right ventricles (RV) by pulmonary artery banding (PAB) to define the time course of changes in fibrillar collagen content after PO using a nonrodent model and to determine whether this time course was dependent on changes in fibroblast function. Total, soluble, and insoluble collagen (hydroxyproline), collagen volume fraction (CVF), and RV end-diastolic pressure were assessed 2 days and 1, 2, 4, and 10 wk following PAB. Fibroblast function was assessed by quantitating the product of postsynthetic processing, insoluble collagen, and levels of SPARC (secreted protein acidic and rich in cysteine), a protein that affects procollagen processing. RV hypertrophic growth was complete 2 wk after PAB. Changes in RV collagen content did not follow the same time course. Two weeks after PAB, there were elevations in total collagen (control RV: 8.84 ± 1.03 mg/g vs. 2-wk PAB: 11.50 ± 0.78 mg/g); however, increased insoluble fibrillar collagen, as measured by CVF, was not detected until 4 wk after PAB (control RV CVF: 1.39 ± 0.25% vs. 4-wk PAB: 4.18 ± 0.87%). RV end-diastolic pressure was unchanged at 2 wk, but increased until 4 wk after PAB. RV fibroblasts isolated after 2-wk PAB had no changes in either insoluble collagen or SPARC expression; however, increases in insoluble collagen and in levels of SPARC were detected in RV fibroblasts from 4-wk PAB. Therefore, the time course of PO-induced RV hypertrophy differs significantly from myocardial fibrosis and diastolic dysfunction. These temporal differences appear dependent on changes in fibroblast function. PMID:22942178

[Role of hemoglobin affinity to oxygen in adaptation to hypoxemia].

PubMed

Kwasiborski, Przemysław Jerzy; Kowalczyk, Paweł; Zieliński, Jakub; Przybylski, Jacek; Cwetsch, Andrzej

2010-04-01

One of the basic mechanisms of adapting to hypoxemia is a decrease in the affinity of hemoglobin for oxygen. This process occurs mainly due to the increased synthesis of 2,3-diphosphoglycerate (2,3-DPG) in the erythrocytes, as well as through the Bohr effect. Hemoglobin with decreased affinity for oxygen increases the oxygenation of tissues, because it gives up oxygen more easily during microcirculation. In foetal circulation, however, at a partial oxygen pressure (pO2) of 25 mmHg in the umbilical vein, the oxygen carrier is type F hemoglobin which has a high oxygen affinity. The commonly accepted role for hemoglobin F is limited to facilitating diffusion through the placenta. Is fetal life the only moment when haemoglobin F is useful? THE AIM OF STUDY was to create a mathematical model, which would answer the question at what conditions an increase, rather than a decrease, in haemoglobin oxygen affinity is of benefit to the body. Using the kinetics of dissociation of oxygen from hemoglobin described by the Hill equation as the basis for further discussion, we created a mathematical model describing the pO2 value in the microcirculatory system and its dependence on arterial blood pO2. The calculations were performed for hemoglobin with low oxygen affinity (adult type) and high-affinity hemoglobin (fetal type). The modelling took into account both physiological and pathological ranges of acid-base equilibrium and tissue oxygen extraction parameters. It was shown that for the physiological range of acid-base equilibrium and the resting level of tissue oxygen extraction parameters, with an arterial blood pO2 of 26.8 mmHg, the higher-affinity hemoglobin becomes the more effective oxygen carrier. It was also demonstrated that the arterial blood pO2, below which the high-affinity hemoglobin becomes the more effective carrier, is dependent on blood pH and the difference between the arterial and venous oxygen saturation levels. Simulations performed for the pathological states showed that acidosis and increased tissue oxygen demand lead to a broadened arterial blood pO2 range, in which the high-affinity hemoglobin is more efficient. Contrary to the widely held view that the only response to hypoxemia is a decrease in haemoglobin oxygen affinity, it was shown that under extreme hypoxemic conditions, an increased haemoglobin oxygen affinity improves the oxygenation of tissues. It was also shown that the dominance of hemoglobin with a high oxygen affinity rapidly exceeds hemoglobin with low oxygen affinity in the case of acidosis with its accompanying high tissue oxygen extraction. In cases of extreme disruptions of the acid-base equilibrium, the dominance of high-oxygen-affinity hemoglobin spans over the entire possible range of pO2 in arterial blood.

Comparison of the OxyMask and Venturi mask in the delivery of supplemental oxygen: Pilot study in oxygen-dependent patients

PubMed Central

Beecroft, Jaime M; Hanly, Patrick J

2006-01-01

BACKGROUND: The OxyMask (Southmedic Inc, Canada) is a new face mask for oxygen delivery that uses a small ‘diffuser’ to concentrate and direct oxygen toward the mouth and nose. The authors hypothesized that this unique design would enable the OxyMask to deliver oxygen more efficiently than a Venturi mask (Hudson RCI, USA) in patients with chronic hypoxemia. METHODS: Oxygen-dependent patients with chronic, stable respiratory disease were recruited to compare the OxyMask and Venturi mask in a randomized, single-blind, cross-over design. Baseline blood oxygen saturation (SaO2) was established breathing room air, followed in a random order by supplemental oxygen through the OxyMask or Venturi mask. Oxygen delivery was titrated to maintain SaO2 4% to 5% and 8% to 9% above baseline for two separate 30 min periods of stable breathing. Oxygen flow rate, partial pressure of inspired and expired oxygen (PO2) and carbon dioxide (PCO2), minute ventilation, heart rate, nasal and oral breathing, SaO2 and transcutaneous PCO2 were collected continuously. The study was repeated following alterations to the OxyMask design, which improved clearance of carbon dioxide. RESULTS: Thirteen patients, aged 28 to 79 years, were studied initially using the original OxyMask. Oxygen flow rate was lower, inspired PO2 was higher and expired PO2 was lower while using the OxyMask. Minute ventilation and inspired and expired PCO2 were significantly higher while using the OxyMask, whereas transcutaneous PCO2, heart rate and the ratio of nasal to oral breathing did not change significantly throughout the study. Following modification of the OxyMask, 13 additional patients, aged 18 to 79 years, were studied using the same protocol. The modified OxyMask provided a higher inspired PO2 at a lower flow rate, without evidence of carbon dioxide retention. CONCLUSIONS: Oxygen is delivered safely and more efficiently by the OxyMask than by the Venturi mask in stable oxygen-dependent patients. PMID:16896425

Stabilization of polar Mn3O4(001) film on Ag(001): Interplay between kinetic and structural stability

NASA Astrophysics Data System (ADS)

Kundu, Asish K.; Barman, Sukanta; Menon, Krishnakumar S. R.

2017-10-01

Stabilization processes of polar surfaces are often very complex and interesting. Understanding of these processes is crucial as it ultimately determines the properties of the film. Here, by the combined study of Low Energy Electron Diffraction (LEED), X-ray Photoelectron Spectroscopy (XPS) and Ultraviolet Photoemission Spectroscopy (UPS) techniques we show that, although there can be many processes involved in the stabilization of the polar surfaces, in case of Mn3O4(001)/Ag(001), it goes through different reconstructions of the Mn2O4 terminated surface which is in good agreements with the theoretical predictions. The complex surface phase diagram has been probed by LEED as a function of film thickness, oxygen partial pressure and substrate temperature during growth, while their chemical compositions have been probed by XPS. Below a critical film thickness of ∼ 1 unit cell height (8 sublayers or 3 ML) of Mn3O4 and oxygen partial pressure range of 2 × 10-8 mbar < P(O2) ≤ 5 × 10-7 mbar, different surface structures are detected and beyond this thickness a constant evolution of apparent p(2 × 2) structure have been observed due to the coexistence of p(2 × 1) and c(2 × 2) structures. Similar apparent p(2 × 2) structure has also observed by the oxidation of Ag(001)-supported MnO(001) surface. Our study also shows that the substrate temperature during growth plays a crucial role in determining the final structure of the polar Mn3O4 film and as a consequence of that a strong interplay between structural and kinetic stability in the Mn3O4 film has been observed. Further, stripe-like LEED pattern has been observed from the Mn3O4(001) surface, for the film grown at higher oxygen partial pressure (> 5 × 10-7 mbar) and higher temperature UHV annealing. The origin of these stripes has been explained with the help of UPS results.

Effects of elevated oxygen and carbon dioxide partial pressures on respiratory function and cognitive performance.

PubMed

Gill, Matthew; Natoli, Michael J; Vacchiano, Charles; MacLeod, David B; Ikeda, Keita; Qin, Michael; Pollock, Neal W; Moon, Richard E; Pieper, Carl; Vann, Richard D

2014-08-15

Hyperoxia during diving has been suggested to exacerbate hypercapnic narcosis and promote unconsciousness. We tested this hypothesis in male volunteers (12 at rest, 10 at 75 W cycle ergometer exercise) breathing each of four gases in a hyperbaric chamber. Inspired Po2 (PiO2 ) was 0.21 and 1.3 atmospheres (atm) without or with an individual subject's maximum tolerable inspired CO2 (PiO2 = 0.055-0.085 atm). Measurements included end-tidal CO2 partial pressure (PetCO2 ), rating of perceived discomfort (RPD), expired minute ventilation (V̇e), and cognitive function assessed by auditory n-back test. The most prominent finding was, irrespective of PetCO2 , that minute ventilation was 8-9 l/min greater for rest or exercise with a PiO2 of 1.3 atm compared with 0.21 atm (P < 0.0001). For hyperoxic gases, PetCO2 was consistently less than for normoxic gases (P < 0.01). For hyperoxic hypercapnic gases, n-back scores were higher than for normoxic gases (P < 0.01), and RPD was lower for exercise but not rest (P < 0.02). Subjects completed 66 hyperoxic hypercapnic trials without incident, but five stopped prematurely because of serious symptoms (tunnel vision, vision loss, dizziness, panic, exhaustion, or near syncope) during 69 normoxic hypercapnic trials (P = 0.0582). Serious symptoms during hypercapnic trials occurred only during normoxia. We conclude serious symptoms with hyperoxic hypercapnia were absent because of decreased PetCO2 consequent to increased ventilation. Copyright © 2014 the American Physiological Society.

Enhanced ubiquitination of cytoskeletal proteins in pressure overloaded myocardium is accompanied by changes in specific E3 ligases.

PubMed

Balasubramanian, Sundaravadivel; Mani, Santhoshkumar; Shiraishi, Hirokazu; Johnston, Rebecca K; Yamane, Kentaro; Willey, Christopher D; Cooper, George; Tuxworth, William J; Kuppuswamy, Dhandapani

2006-10-01

Ubiquitin conjugation of proteins is critical for cell homeostasis and contributes to both cell survival and death. Here we studied ubiquitination of proteins in pressure overloaded (PO) myocardium in the context of cardiomyocyte survival. Analysis using a feline right ventricular pressure overload (RVPO) model revealed a robust and transient increase in ubiquitination of proteins present in the Triton X-100-insoluble fraction in 24 to 48 h PO myocardium, and confocal micrographs indicate this increase in ubiquitination occurs subsarcolemmaly near the intercalated disc area of cardiomyocytes. The ubiquitination was accompanied by changes in E3 ligases including Cbl, E6AP, Mdm2 and cIAP in the same period of PO, although atrophy-related E3 ligases, MuRF1 and MuRF3 were unaltered. Furthermore, Cbl displayed a substantial increase in both levels of expression and tyrosine phosphorylation in 48 h PO myocardium. Confocal studies revealed enrichment of Cbl at the intercalated discs of 48 h PO cardiomyocytes, as evidenced by its colocalization with N-cadherin. Although apoptosis was observed in 48 h PO myocardium by TUNEL staining, cardiomyocytes showing ubiquitin staining were not positive for TUNEL staining. Furthermore, 48 h PO resulted in the phosphorylation of inhibitor of nuclear factor kappa B (IkappaB), suggesting its ubiquitin-mediated degradation and the nuclear localization of NFkappaB for the expression of specific cell survival factors such as cIAPs. Together these data indicate that increased levels of E3 ligases that regulate cell homeostasis and promote cell survival could ubiquitinate multiple cytoskeletal protein targets and that these events that occur during the early phase of PO may contribute to both cardiomyocyte survival and hypertrophy.

Sulfur and sulfides in chondrules

NASA Astrophysics Data System (ADS)

Marrocchi, Yves; Libourel, Guy

2013-10-01

The nature and distribution of sulfides within type I PO, POP and PP chondrules of the carbonaceous chondrite Vigarano (CV3) have been studied by secondary electron microscopy and electron microprobe. They occur predominantly as spheroidal blebs composed entirely of low-Ni iron sulfide (troilite, FeS) or troilite + magnetite but in less abundance in association with metallic Fe-Ni beads in opaque assemblages. Troilites are mainly located within the low-Ca pyroxene outer zone and their amounts increase with the abundance of low-Ca pyroxene within chondrules, suggesting co-crystallization of troilite and low-Ca pyroxene during high-temperature events. We show that sulfur concentration and sulfide occurrence in chondrules obey high temperature sulfur solubility and saturation laws. Depending on the fS2 and fO2 of the surrounding gas and on the melt composition, mainly the FeO content, sulfur dissolved in chondrule melts may eventually reach a concentration limit, the sulfur content at sulfide saturation (SCSS), at which an immiscible iron sulfide liquid separates from the silicate melt. The occurrence of both a silicate melt and an immiscible iron sulfide liquid is further supported by the non-wetting behavior of sulfides on silicate phases in chondrules due to the high interfacial tension between their precursor iron-sulfide liquid droplets and the surrounding silicate melt during the high temperature chondrule-forming event. The evolution of chondrule melts from PO to PP towards more silicic compositions, very likely due to high PSiO(g) of the surrounding nebular gas, induces saturation of FeS at much lower S content in PP than in PO chondrules, leading to the co-crystallization of iron sulfides and low-Ca pyroxenes. Conditions of co-saturation of low-Ca pyroxene and FeS are only achieved in non canonical environments characterized by high partial pressures of sulfur and SiO and redox conditions more oxidizing than IW-3. Fe and S mass balance calculations also suggest the occurrence of an external source of iron, very likely gaseous, during chondrule formation. We therefore propose that enrichments in sulfur (and other volatile and moderately volatile elements) from PO to PP type I bulk chondrule compositions towards chondritic values result from progressive reaction between partially depleted olivine-bearing precursors and a volatile-rich gas phase.

Effects of the nitric oxide synthase inhibitor L-NMMA on cerebrovascular and cardiovascular responses to hypoxia and hypercapnia in humans.

PubMed

Ide, Kojiro; Worthley, Matthew; Anderson, Todd; Poulin, Marc J

2007-10-01

Cerebral blood flow is highly sensitive to alterations in the partial pressures of O(2) and CO(2) (P(O(2)) and P(CO(2)), respectively) in the arterial blood. In humans, the extent to which nitric oxide (NO) is involved in this regulation is unclear. We hypothesized that the NO synthase (NOS) inhibitor N(G)-monomethyl-l-arginine (l-NMMA), attenuates the sensitivity of middle cerebral artery blood velocity (V(p)) to isocapnic hypoxia (end-tidal P(O(2)) = 50 Torr) and euoxic hypercapnia (end-tidal P(CO(2)) = +9 Torr above resting values) in 10 volunteers (age, 28.7 +/- 1.3 years; height, 179.2 +/- 2.4 cm; weight, 78.0 +/- 3.7 kg; mean +/- s.e.m.). The techniques of transcranial Doppler ultrasound and dynamic end-tidal forcing were used to measure(V(p)), and control end-tidal P(O(2)) and end-tidal P(CO(2)), respectively. At baseline (isocapnic euoxia), following intravenous administration of l-NMMA, mean arterial blood pressure (MAP) increased (76.3 +/- 7.3 to 86.2 +/- 9.4 mmHg) and heart rate (HR) decreased (59.5 +/- 9.0 to 55.2 +/- 9.5 beats min(-1)) but (V(p)) was unchanged. Hypoxia-induced increases in MAP, HR and were similar with and without l-NMMA (5.0 +/- 0.7 versus 7.1 +/- 1.0 mmHg, 11.5 +/- 1.4 versus 12.4 +/- 1.5 beats min(-1), 6.5 +/- 0.8 versus 6.6 +/- 0.8 cm s(-1) for DeltaMAP, DeltaHR and Delta , respectively). Hypercapnia-induced increases in MAP, HR and (V(p)) were similar with and without l-NMMA (7.4 +/- 3.1 versus 8.1 +/- 2.2 mmHg, 10.4 +/- 4.6 versus 10.0 +/- 4.2 beats min(-1), 16.5 +/- 1.5 versus 17.6 +/- 1.5 cm s(-1) for DeltaMAP, DeltaHR and Delta(V(p)) , respectively) but the sensitivity of the(V(p)) response at the removal of hypercapnia was attenuated with l-NMMA. In young healthy humans, pharmacological blockade of nitric oxide synthesis does not affect the increases in cerebral blood flow with hypoxia and hypercapnia, suggesting that nitric oxide is not required for the cerbrovascular responses to hypoxia and hypercapnia.

Rapamycin treatment augments both protein ubiquitination and Akt activation in pressure-overloaded rat myocardium

PubMed Central

Harston, Rebecca K.; McKillop, John C.; Moschella, Phillip C.; Van Laer, An; Quinones, Lakeya S.; Baicu, Catalin F.; Balasubramanian, Sundaravadivel; Zile, Michael R.

2011-01-01

Ubiquitin-mediated protein degradation is necessary for both increased ventricular mass and survival signaling for compensated hypertrophy in pressure-overloaded (PO) myocardium. Another molecular keystone involved in the hypertrophic growth process is the mammalian target of rapamycin (mTOR), which forms two distinct functional complexes: mTORC1 that activates p70S6 kinase-1 to enhance protein synthesis and mTORC2 that activates Akt to promote cell survival. Independent studies in animal models show that rapamycin treatment that alters mTOR complexes also reduces hypertrophic growth and increases lifespan by an unknown mechanism. We tested whether the ubiquitin-mediated regulation of growth and survival in hypertrophic myocardium is linked to the mTOR pathway. For in vivo studies, right ventricle PO in rats was conducted by pulmonary artery banding; the normally loaded left ventricle served as an internal control. Rapamycin (0.75 mg/kg per day) or vehicle alone was administered intraperitoneally for 3 days or 2 wk. Immunoblot and immunofluorescence imaging showed that the level of ubiquitylated proteins in cardiomyocytes that increased following 48 h of PO was enhanced by rapamycin. Rapamycin pretreatment also significantly increased PO-induced Akt phosphorylation at S473, a finding confirmed in cardiomyocytes in vitro to be downstream of mTORC2. Analysis of prosurvival signaling in vivo showed that rapamycin increased PO-induced degradation of phosphorylated inhibitor of κB, enhanced expression of cellular inhibitor of apoptosis protein 1, and decreased active caspase-3. Long-term rapamycin treatment in 2-wk PO myocardium blunted hypertrophy, improved contractile function, and reduced caspase-3 and calpain activation. These data indicate potential cardioprotective benefits of rapamycin in PO hypertrophy. PMID:21357504

Burn trauma in skeletal muscle results in oxidative stress as assessed by in vivo electron paramagnetic resonance

PubMed Central

KHAN, NADEEM; MUPPARAJU, SRIRAM P.; MINTZOPOULOS, DIONYSSIOS; KESARWANI, MEENU; RIGHI, VALERIA; RAHME, LAURENCE G.; SWARTZ, HAROLD M.; TZIKA, A. ARIA

2010-01-01

Using a mouse model, we tested the hypotheses that severe burn trauma causes metabolic disturbances in skeletal muscle, and that these can be measured and repeatedly followed by in vivo electron paramagnetic resonance (EPR). We used a 1.2-GHz (L-band) EPR spectrometer to measure partial pressure of oxygen (pO2) levels, redox status and oxidative stress following a non-lethal burn trauma model to the left hind limbs of mice. Results obtained in the burned mouse gastrocnemius muscle indicated a significant decrease in tissue pO2 immediately (P=0.032) and at 6 h post burn (P=0.004), compared to the gastrocnemius of the unburned hind limb. The redox status of the skeletal muscle also peaked at 6 h post burn (P=0.027) in burned mice. In addition, there was an increase in the EPR signal of the nitroxide produced by oxidation of the hydroxylamine (CP-H) probe at 12 h post burn injury, indicating a burn-induced increase in mitochondrial reactive oxygen species (ROS). The nitroxide signal continued to increase between 12 and 24 h, suggesting a further increase in ROS generation post burn. These results confirm genomic results, which indicate a downregulation of antioxidant genes and therefore strongly suggest the dysfunction of the mitochondrial oxidative system. We believe that the direct measurement of tissue parameters such as pO2, redox and ROS by EPR may be used to complement measurements by nuclear magnetic resonance (NMR) in order to assess tissue damage and the therapeutic effectiveness of antioxidant agents in severe burn trauma. PMID:21179378

Prophylactic Oral Administration of Magnesium Ameliorates Dextran Sulfate Sodium-Induced Colitis in Mice through a Decrease of Colonic Accumulation of P2X7 Receptor-Expressing Mast Cells.

PubMed

Ohbori, Kenshi; Fujiwara, Makiko; Ohishi, Akihiro; Nishida, Kentaro; Uozumi, Yoshinobu; Nagasawa, Kazuki

2017-01-01

The number of patients with colitis has been increasing year by year. Recently, intestinal inflammation, as one of the factors for its onset, has been demonstrated to be induced by P2X7 receptor-mediated activation of colonic immune cells such as mast cells. Activation of P2X7 receptor (P2X7R) is known to be inhibited by divalent metal cations such as magnesium, but whether or not magnesium administration prevents/relieves colitis is unknown so far. Here, we report that oral (per os (p.o.)) administration of MgCl 2 and ingestion of commercially available magnesium-rich mineral hard water relieves dextran sulfate sodium (DSS)-induced colitis in mice. Colitis was induced through ingestion of a 3% (w/v) DSS solution ad libitum for 10 d. Brilliant blue G (BBG, a P2X7R antagonist), MgCl 2 or magnesium-rich mineral hard water was administered p.o. to mice via gastric intubation once a day or ad libitum from a day before DSS administration for 11 times or 11 d, respectively. DSS-treated mice exhibited a low disease activity index, a short colon and a high histological score compared to in control mice. As BBG (250 mg/kg, p.o.), administration of a MgCl 2 solution (100 or 500 mg/kg, p.o.) and ad libitum ingestion of the magnesium-rich mineral hard water (212 ppm as magnesium) partially, but significantly, attenuated the severity of colitis by decreasing the accumulation of P2X7R-immunopositive mast cells in the colon. Therefore, prophylactic p.o. administration/ingestion of magnesium is considered to be partially effective to protect mice against DSS-induced colitis by inhibiting P2X7R-mediated activation/accumulation of colonic mast cells.

Near-infrared spectroscopic analysis of the breaking force of extended-release matrix tablets prepared by roller-compaction: influence of plasticizer levels and sintering temperature.

PubMed

Dave, Vivek S; Fahmy, Raafat M; Hoag, Stephen W

2015-06-01

The aim of this study was to investigate the feasibility of near-infrared (NIR) spectroscopy for the determination of the influence of sintering temperature and plasticizer levels on the breaking force of extended-release matrix tablets prepared via roller-compaction. Six formulations using theophylline as a model drug, Eudragit® RL PO or Eudragit® RS PO as a matrix former and three levels of TEC (triethyl citrate) as a plasticizer were prepared. The powder blend was roller compacted using a fixed roll-gap of 1.5 mm, feed screw speed to roller speed ratio of 5:1 and roll pressure of 4 MPa. The granules, after removing fines, were compacted into tablets on a Stokes B2 rotary tablet press at a compression force of 7 kN. The tablets were thermally treated at different temperatures (Room Temperature, 50, 75 and 100 °C) for 5 h. These tablets were scanned in reflectance mode in the wavelength range of 400-2500 nm and were evaluated for breaking force. Tablet breaking force significantly increased with increasing plasticizer levels and with increases in the sintering temperature. An increase in tablet hardness produced an upward shift (increase in absorbance) in the NIR spectra. The principle component analysis (PCA) of the spectra was able to distinguish samples with different plasticizer levels and sintering temperatures. In addition, a 9-factor partial least squares (PLS) regression model for tablets containing Eudragit® RL PO had an r(2) of 0.9797, a standard error of calibration of 0.6255 and a standard error of cross validation (SECV) of 0.7594. Similar analysis of tablets containing Eudragit® RS PO showed an r(2) of 0.9831, a standard error of calibration of 0.9711 and an SECV of 1.192.

Over-expression of copper/zinc superoxide dismutase in the median preoptic nucleus attenuates chronic angiotensin II-induced hypertension in the rat.

PubMed

Collister, John P; Bellrichard, Mitch; Drebes, Donna; Nahey, David; Tian, Jun; Zimmerman, Matthew C

2014-12-02

The brain senses circulating levels of angiotensin II (AngII) via circumventricular organs, such as the subfornical organ (SFO), and is thought to adjust sympathetic nervous system output accordingly via this neuro-hormonal communication. However, the cellular signaling mechanisms involved in these communications remain to be fully understood. Previous lesion studies of either the SFO, or the downstream median preoptic nucleus (MnPO) have shown a diminution of the hypertensive effects of chronic AngII, without providing a clear explanation as to the intracellular signaling pathway(s) involved. Additional studies have reported that over-expressing copper/zinc superoxide dismutase (CuZnSOD), an intracellular superoxide (O2·-) scavenging enzyme, in the SFO attenuates chronic AngII-induced hypertension. Herein, we tested the hypothesis that overproduction of O2·- in the MnPO is an underlying mechanism in the long-term hypertensive effects of chronic AngII. Adenoviral vectors encoding human CuZnSOD (AdCuZnSOD) or control vector (AdEmpty) were injected directly into the MnPO of rats implanted with aortic telemetric transmitters for recording of arterial pressure. After a 3 day control period of saline infusion, rats were intravenously infused with AngII (10 ng/kg/min) for ten days. Rats over-expressing CuZnSOD (n = 7) in the MnPO had a blood pressure increase of only 6 ± 2 mmHg after ten days of AngII infusion while blood pressure increased 21 ± 4 mmHg in AdEmpty-infected rats (n = 9). These results support the hypothesis that production of O2·- in the MnPO contributes to the development of chronic AngII-dependent hypertension.

Effect of sodium nitrite on local control of contracting skeletal muscle microvascular oxygen pressure in healthy rats.

PubMed

Colburn, Trenton D; Ferguson, Scott K; Holdsworth, Clark T; Craig, Jesse C; Musch, Timothy I; Poole, David C

2017-01-01

Exercise intolerance characteristic of diseases such as chronic heart failure (CHF) and diabetes is associated with reduced nitric oxide (NO) bioavailability from nitric oxide synthase (NOS), resulting in an impaired microvascular O 2 driving pressure (Po 2 mv; O 2 delivery/O 2 utilization) and metabolic control. Infusions of the potent NO donor sodium nitroprusside augment NO bioavailability yet decrease mean arterial pressure (MAP) thereby reducing its potential efficacy for patient populations. To eliminate or reduce hypotensive sequelae, [Formula: see text] was superfused onto the spinotrapezius muscle. It was hypothesized that local [Formula: see text] administration would elevate resting Po 2 mv and slow Po 2 mv kinetics [increased time constant (τ) and mean response time (MRT)] following the onset of muscle contractions without decreasing MAP. In 12 anesthetized male Sprague-Dawley rats, Po 2 mv of the circulation-intact spinotrapezius muscle was measured by phosphorescence quenching during 180 s of electrically induced twitch contractions (1 Hz) before and after superfusion of sodium nitrite (NaNO 2 30 mM). [Formula: see text] superfusion elevated resting Po 2 mv (control: 28.4 ± 1.1 vs. [Formula: see text]: 31.6 ± 1.2 mmHg; P ≤ 0.05), τ (control: 12.3 ± 1.2 vs. [Formula: see text]: 19.7 ± 2.2 s; P ≤ 0.05), and MRT (control: 19.3 ± 1.9 vs. [Formula: see text]: 25.6 ± 3.3 s; P ≤ 0.05). Importantly, these effects occurred in the absence of any reduction in MAP (103 ± 4 vs. 105 ± 4 mmHg, pre- and postsuperfusion respectively; P > 0.05). These results indicate that [Formula: see text] supplementation delivered to the muscle directly through [Formula: see text] superfusion enhances the blood-myocyte oxygen driving pressure without compromising MAP at rest and following the onset of muscle contraction. This strategy has substantial clinical utility for a range of ischemic conditions. Ischemic conditions as diverse as chronic heart failure (CHF) and frostbite inflict tissue damage via inadequate O 2 delivery. Herein we demonstrate that direct application of sodium nitrite enhances the O 2 supply-O 2 demand relationship, raising microvascular O 2 pressure in healthy skeletal muscle. This therapeutic action of nitrite-derived nitric oxide occurred without inducing systemic hypotension and has the potential to relieve focal ischemia and preserve tissue vitality by enhancing O 2 delivery. Copyright © 2017 the American Physiological Society.

Theory and computation of triply excited resonances: Application to states of He-

NASA Astrophysics Data System (ADS)

Nicolaides, Cleanthes A.; Piangos, Nicos A.; Komninos, Yannis

1993-11-01

Autoionizing multiply excited states offer unusual challenges to the theory of electronic structure and spectra because of the presence of strong electron correlations, of their occasional weak binding, of their proximity to more than one threshold, and of their degeneracy with many continua. Here we discuss a theory that addresses these difficulties in conjunction with the computation of their wave functions and intrinsic properties. Emphasis is given on the justification of the possible presence of self-consistently obtained open-channel-like (OCL) correlating configurations in the square-integrable representation of such states and on their effect on the energy E and the width Γ. Application of the theory has allowed the prediction of two hitherto unknown He- triply excited resonances, the 2s2p2 2P (E=59.71 eV, above the He ground state, Γ=79 meV) and the 2p3 2Do (E=59.46 eV, Γ=282 meV) (1 a.u.=27.2116 eV). These resonances are above the singly excited states of He and are embedded in its doubly excited spectrum. The relatively broad 2p3 2Do state interacts strongly with the He 2s2p 3Po ɛd continuum. The effect of this interaction has been studied in terms of the coupling with fixed core scattering states as well as with a self-consistently computed OCL bound configuration. The position of the He- 2p3 2Do resonance is below that of the He 2p2 1D autoionizing state at 59.91 eV and of the He 2p2 3P bound state at 59.68 eV. The partial decay widths to the three important open channels are γ(2s2p 3Po)=252 meV, γ(1s2p 3Po)=21 meV, γ(1s2p 1Po)=9 meV. The final core states are also represented by correlated (multiconfigurational Hartree-Fock) functions. The 2s2p2 2P state couples to four neighboring He thresholds, the 2s2p 3Po, 2p2 3P, 1D, and 2s2p 1Po. It is above the He 2s2p 3Po threshold at 58.31 eV, with respect to which it is a valence shape resonance, and below the He 2p2 1D and 2s2p 1Po autoionizing states. In the limit of an exact energy calculation, we suggest that its position would also come below that of the 2p2 3P state, which it overlaps. Its partial widths are γ(2s2p 3Po)=60 meV, γ(1s2p 3Po)=9 meV, γ(1s2p 1Po)=10 meV. The present results, considered together with published ones on other n=2 intrashell states, show that the recently measured [R. N. Gosselin and P. Marmet, Phys. Rev. A 41, 1335 (1990)] closely lying structures at 58.415 and 58.48 eV cannot correspond to the He- 2p3 4So and 2Do states, as these authors proposed.

The possible protective role of pumpkin seed oil in an animal model of acid aspiration pneumonia: Light and electron microscopic study.

PubMed

Omar, Nesreen Moustafa; Sarhan, Nahla Reda

2017-03-01

Aspiration pneumonitis is a common problem occurring in many clinical disorders. Pumpkin seed oil (PO) is a rich source of antioxidants. This work aimed to assess the effect of PO on the lung histopathological changes induced by acid aspiration. Forty male albino rats assigned to four groups were used. Rats of control group were instilled intratracheally with normal saline 2mL/kg. HCL group instilled with 2mL/kg of HCL 0.1N, pH 1.25. PO group received pumpkin seed oil (PO) orally (∼1375mg/kgbw/day) for 7days. HCL+PO group instilled with 2mL/kg of HCL 0.1N, pH 1.25 and received PO at the same dose of PO group. Lung tissue samples were processed for light, electron microscopic and immunohistochemical study using anti inducible NO synthase (iNOS). The lung of HCL group demonstrated thickened interalveolar septa, inflammatory cell infiltration and significant increase in the area percent of collagenous fibers and immune expression of iNOS. Ultra structurally, disrupted alveolocapillay membrane, degenerated type II pneumocytes and plentiful alveolar macrophages were evident. PO administration partially attenuated these histological and ultra structural alterations and reduced iNOS immune-expression in lung tissue. In conclusion, PO has a protective effect against HCL aspiration lung injury most probably through its antioxidant activity. Copyright © 2017 Elsevier GmbH. All rights reserved.

The Ferguson principle and an analysis of biological activity of gases and vapors.

PubMed

Abraham, M H; Nielsen, G D; Alarie, Y

1994-05-01

The Ferguson principle, that Pnar/PO (Pnar is the partial pressure of a series of compounds giving rise to a particular effect on a given system by a physical mechanism, and PO is the saturated vapor pressure of the liquid narcotic) is constant for a series of nonreactive narcotics or toxicants in a given system, is examined and shown to have no thermodynamic basis, contrary to the position of Brink and Posternak. Conditions under which Pnar/PO might be expected to be roughly constant, as an empirical observation, are set out and it is shown that such an observation is consistent with a receptor area in which the liquid narcotic solubilities are roughly constant. An interpretation of relationships between agonist descriptors and biological effects is carried out with three simple biological models. It is shown that the biological potency of nonreactive gases and vapors can be controlled either by an equilibrium between the agonist in the gas phase and the agonist in a receptor or by an equilibrium between the agonist in the gas phase and the agonist in a receptor phase. It is further shown that with the solvation equation of Abraham, solvents can be chosen that mimic the chemical properties of the receptor or receptor phase. For the example of upper respiratory tract irritation of male Swiss OF1 mice, such solvents include N-formylmorpholine, a trialkylphosphate, and wet octanol, but not water itself.

Exploring the high-pressure behavior of the three known polymorphs of BiPO{sub 4}: Discovery of a new polymorph

DOE Office of Scientific and Technical Information (OSTI.GOV)

Errandonea, D., E-mail: daniel.errandonea@uv.es; García-Domene, B.; Gomis, O.

We have studied the structural behavior of bismuth phosphate under compression. We performed x-ray powder diffraction measurements up to 31.5 GPa and ab initio calculations. Experiments were carried out on different polymorphs: trigonal (phase I) and monoclinic (phases II and III). Phases I and III, at low pressure (P < 0.2–0.8 GPa), transform into phase II, which has a monazite-type structure. At room temperature, this polymorph is stable up to 31.5 GPa. Calculations support these findings and predict the occurrence of an additional transition from the monoclinic monazite-type to a tetragonal scheelite-type structure (phase IV). This transition was experimentally found after the simultaneous applicationmore » of pressure (28 GPa) and temperature (1500 K), suggesting that at room temperature the transition might by hindered by kinetic barriers. Calculations also predict an additional phase transition at 52 GPa, which exceeds the maximum pressure achieved in the experiments. This transition is from phase IV to an orthorhombic barite-type structure (phase V). We also studied the axial and bulk compressibility of BiPO{sub 4}. Room-temperature pressure-volume equations of state are reported. BiPO{sub 4} was found to be more compressible than isomorphic rare-earth phosphates. The discovered phase IV was determined to be the less compressible polymorph of BiPO{sub 4}. On the other hand, the theoretically predicted phase V has a bulk modulus comparable with that of monazite-type BiPO{sub 4}. Finally, the isothermal compressibility tensor for the monazite-type structure is reported at 2.4 GPa showing that the direction of maximum compressibility is in the (0 1 0) plane at approximately 15° (21°) to the a axis for the case of our experimental (theoretical) study.« less

Pressure signatures can influence tissue response for individuals supported on an alternating pressure mattress.

PubMed

Chai, C Y; Sadou, O; Worsley, P R; Bader, D L

2017-08-01

Prolonged mechanical loading can lead to the breakdown of skin and underlying tissues which can, in turn, develop into a pressure ulcer. The benefits of pressure relief and/or redistribution to minimise risk have been well documented. Manufacturers have developed alternating air pressure mattresses (APAMs) to provide periodic relief for individuals on prolonged bed-rest. The present study describes the development of a control system, termed Pneumatic Manager which can vary the signature of an APAM, namely its pressure amplitude, cell profile and cycle period. An experimental array was designed to investigate the effects of varying these parameters, particularly with respect to its ability to maintain skin viability in a group of five healthy volunteers lying in a supine position. Transcutaneous gas (T c PO 2 /T c PCO 2 ) tensions at the sacrum were monitored. In addition, pressures and microclimate parameters at the loaded support interface were also measured. In the majority of test conditions the alternating support produced sacral T c PO 2 values, which either remained relatively high or fluctuated in concert with cycle period providing adequate viability. However, in 46% of cases at the extreme pressure amplitude of 100/0 mmHg, there was compromise to the skin viability at the sacrum, as reflected in depressed T c PO 2 levels associated with an elevation of T c PCO 2 levels above the normal range. In all cases, both the humidity and temperature levels increased during the test period. It is interesting to note that interface pressures at the sacrum rarely exceeded 60 mmHg. Although such studies need to be extended to involve bed-bound individuals, the results provide a design template for the optimum pressure signatures of APAM systems to ensure maintenance of skin viability during pronged loading. Copyright © 2017 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

Isolated human islets require hyperoxia to maintain islet mass, metabolism, and function.

PubMed

Komatsu, Hirotake; Kang, Dongyang; Medrano, Leonard; Barriga, Alyssa; Mendez, Daniel; Rawson, Jeffrey; Omori, Keiko; Ferreri, Kevin; Tai, Yu-Chong; Kandeel, Fouad; Mullen, Yoko

2016-02-12

Pancreatic islet transplantation has been recognized as an effective treatment for Type 1 diabetes; however, there is still plenty of room to improve transplantation efficiency. Because islets are metabolically active they require high oxygen to survive; thus hypoxia after transplant is one of the major causes of graft failure. Knowing the optimal oxygen tension for isolated islets would allow a transplant team to provide the best oxygen environment during pre- and post-transplant periods. To address this issue and begin to establish empirically determined guidelines for islet maintenance, we exposed in vitro cultured islets to different partial oxygen pressures (pO2) and assessed changes in islet volume, viability, metabolism, and function. Human islets were cultured for 7 days in different pO2 media corresponding to hypoxia (90 mmHg), normoxia (160 mmHg), and hyerpoxia (270 or 350 mmHg). Compared to normoxia and hypoxia, hyperoxia alleviated the loss of islet volume, maintaining higher islet viability and metabolism as measured by oxygen consumption and glucose-stimulated insulin secretion responses. We predict that maintaining pre- and post-transplanted islets in a hyperoxic environment will alleviate islet volume loss and maintain islet quality thereby improving transplant outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

Acidosis, but Not Alkalosis, Affects Anaerobic Metabolism and Performance in a 4-km Time Trial.

PubMed

Correia-Oliveira, Carlos Rafaell; Lopes-Silva, João Paulo; Bertuzzi, Romulo; McConell, Glenn K; Bishop, David John; Lima-Silva, Adriano Eduardo; Kiss, Maria Augusta Peduti Dal'molin

2017-09-01

This study aimed to determine the effect of preexercise metabolic acidosis and alkalosis on power output (PO) and aerobic and anaerobic energy expenditure during a 4-km cycling time trial (TT). Eleven recreationally trained cyclists (V˙O2peak 54.1 ± 9.3 mL·kg·min) performed a 4-km TT 100 min after ingesting in a double-blind matter 0.15 g·kg of body mass of ammonium chloride (NH4Cl, acidosis), 0.3 g·kg of sodium bicarbonate (NaHCO3, alkalosis), or 0.15 g·kg of CaCO3 (placebo). A preliminary study (n = 7) was conducted to establish the optimal doses to promote the desirable preexercise blood pH alterations without gastrointestinal distress. Data for PO, aerobic and anaerobic energy expenditure, and blood and respiratory parameters were averaged for each 1 km and compared between conditions using two-way repeated-measures ANOVA (condition and distance factors). Gastrointestinal discomfort was analyzed qualitatively. Compared with placebo (pH 7.37 ± 0.02, [HCO3]: 27.5 ± 2.6 mmol·L), the NaHCO3 ingestion resulted in a preexercise blood alkalosis (pH +0.06 ± 0.04, [HCO3]: +4.4 ± 2.0 mmol·L, P < 0.05), whereas NH4Cl resulted in a blood acidosis (pH -0.05 ± 0.03, [HCO3]: -4.8 ± 2.1 mmol·L, P < 0.05). Anaerobic energy expenditure rate and PO were reduced throughout the trial in NH4Cl compared with placebo and NaHCO3, resulting in a lower total anaerobic work and impaired performance (P < 0.05). Plasma lactate, V˙CO2, and end-tidal CO2 partial pressure were lower and the V˙E/V˙CO2 higher throughout the trial in NH4Cl compared with placebo and NaHCO3 (P < 0.05). There was no difference between NaHCO3 and placebo for any of these variables (P > 0.05). Minimal gastrointestinal distress was noted in all conditions. Preexercise acidosis, but not alkalosis, affects anaerobic metabolism and PO during a 4-km cycling TT.

Collisional excitation of interstellar PO(X2Π) by He: new ab initio potential energy surfaces and scattering calculations

NASA Astrophysics Data System (ADS)

Lique, François; Jiménez-Serra, Izaskun; Viti, Serena; Marinakis, Sarantos

2018-01-01

We present the first ab initio potential energy surfaces (PESs) for the PO(X2Π)-He van der Waals system. The PESs were obtained using the open-shell partially spin-restricted coupled cluster approach with single, double and perturbative triple excitations [UCCSD(T)]. The augmented correlation-consistent polarized valence triple-zeta (aug-cc-pVTZ) basis set was employed supplemented by mid-bond functions. Integral and differential cross sections for the rotational excitation in PO-He collisions were calculated using the new PES and compared with results in similar systems. Finally, our work presents the first hyperfine-resolved cross sections for this system that are needed for accurate modelling in astrophysical environments.

In vivo imaging and analysis of cerebrovascular hemodynamic responses and tissue oxygenation in the mouse brain.

PubMed

Kisler, Kassandra; Lazic, Divna; Sweeney, Melanie D; Plunkett, Shane; El Khatib, Mirna; Vinogradov, Sergei A; Boas, David A; Sakadži, Sava; Zlokovic, Berislav V

2018-06-01

Cerebrovascular dysfunction has an important role in the pathogenesis of multiple brain disorders. Measurement of hemodynamic responses in vivo can be challenging, particularly as techniques are often not described in sufficient detail and vary between laboratories. We present a set of standardized in vivo protocols that describe high-resolution two-photon microscopy and intrinsic optical signal (IOS) imaging to evaluate capillary and arteriolar responses to a stimulus, regional hemodynamic responses, and oxygen delivery to the brain. The protocol also describes how to measure intrinsic NADH fluorescence to understand how blood O 2 supply meets the metabolic demands of activated brain tissue, and to perform resting-state absolute oxygen partial pressure (pO 2 ) measurements of brain tissue. These methods can detect cerebrovascular changes at far higher resolution than MRI techniques, although the optical nature of these techniques limits their achievable imaging depths. Each individual procedure requires 1-2 h to complete, with two to three procedures typically performed per animal at a time. These protocols are broadly applicable in studies of cerebrovascular function in healthy and diseased brain in any of the existing mouse models of neurological and vascular disorders. All these procedures can be accomplished by a competent graduate student or experienced technician, except the two-photon measurement of absolute pO 2 level, which is better suited to a more experienced, postdoctoral-level researcher.

Evaluating the effect of sample type on American alligator (Alligator mississippiensis) analyte values in a point-of-care blood analyser

PubMed Central

Hamilton, Matthew T.; Finger, John W.; Winzeler, Megan E.; Tuberville, Tracey D.

2016-01-01

The assessment of wildlife health has been enhanced by the ability of point-of-care (POC) blood analysers to provide biochemical analyses of non-domesticated animals in the field. However, environmental limitations (e.g. temperature, atmospheric humidity and rain) and lack of reference values may inhibit researchers from using such a device with certain wildlife species. Evaluating the use of alternative sample types, such as plasma, in a POC device may afford researchers the opportunity to delay sample analysis and the ability to use banked samples. In this study, we examined fresh whole blood, fresh plasma and frozen plasma (sample type) pH, partial pressure of carbon dioxide (PCO2), bicarbonate (HCO3−), total carbon dioxide (TCO2), base excess (BE), partial pressure of oxygen (PO2), oxygen saturation (sO2) and lactate concentrations in 23 juvenile American alligators (Alligator mississippiensis) using an i-STAT CG4+ cartridge. Our results indicate that sample type had no effect on lactate concentration values (F2,65 = 0.37, P = 0.963), suggesting that the i-STAT analyser can be used reliably to quantify lactate concentrations in fresh and frozen plasma samples. In contrast, the other seven blood parameters measured by the CG4+ cartridge were significantly affected by sample type. Lastly, we were able to collect blood samples from all alligators within 2 min of capture to establish preliminary reference ranges for juvenile alligators based on values obtained using fresh whole blood. PMID:27382469

First Reprocessing of Southern Hemisphere ADditional OZonesondes Profile Records: 3. Uncertainty in Ozone Profile and Total Column

NASA Astrophysics Data System (ADS)

Witte, Jacquelyn C.; Thompson, Anne M.; Smit, Herman G. J.; Vömel, Holger; Posny, Françoise; Stübi, Rene

2018-03-01

Reprocessed ozonesonde data from eight SHADOZ (Southern Hemisphere ADditional OZonesondes) sites have been used to derive the first analysis of uncertainty estimates for both profile and total column ozone (TCO). The ozone uncertainty is a composite of the uncertainties of the individual terms in the ozone partial pressure (PO3) equation, those being the ozone sensor current, background current, internal pump temperature, pump efficiency factors, conversion efficiency, and flow rate. Overall, PO3 uncertainties (ΔPO3) are within 15% and peak around the tropopause (15 ± 3 km) where ozone is a minimum and ΔPO3 approaches the measured signal. The uncertainty in the background and sensor currents dominates the overall ΔPO3 in the troposphere including the tropopause region, while the uncertainties in the conversion efficiency and flow rate dominate in the stratosphere. Seasonally, ΔPO3 is generally a maximum in the March-May, with the exception of SHADOZ sites in Asia, for which the highest ΔPO3 occurs in September-February. As a first approach, we calculate sonde TCO uncertainty (ΔTCO) by integrating the profile ΔPO3 and adding the ozone residual uncertainty, derived from the McPeters and Labow (2012, doi:10.1029/2011JD017006) 1σ ozone mixing ratios. Overall, ΔTCO are within ±15 Dobson units (DU), representing 5-6% of the TCO. Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument (TOMS and OMI) satellite overpasses are generally within the sonde ΔTCO. However, there is a discontinuity between TOMS v8.6 (1998 to September 2004) and OMI (October 2004-2016) TCO on the order of 10 DU that accounts for the significant 16 DU overall difference observed between sonde and TOMS. By comparison, the sonde-OMI absolute difference for the eight stations is only 4 DU.

Development of an Animal Model for Burn-Blast Combined Injury and Cardiopulmonary System Changes in the Early Shock Stage.

PubMed

Hu, Quan; Chai, Jiake; Hu, Sen; Fan, Jun; Wang, Hong-Wei; Ma, Li; Duan, Hong-Jie; Liu, Lingying; Yang, Hongming; Li, Bai-Ling; Wang, Yi-He

2015-12-01

The purposes of this study were to establish an animal model for burn-blast combined injury research and elaborate cardiopulmonary system changes in the early shock stage. In this study, royal demolition explosive or RDX (hexagon, ring trimethylene nitramine) was used as an explosive source, and the injury conditions of the canine test subjects at various distances to the explosion (30, 50, and 70 cm) were observed by gross anatomy and pathology to determine a larger animal model of moderate blast injury. The canines were then subjected to a 35 % total body surface area (TBSA) full-thickness flame injury using napalm, which completed the development of a burn-blast combined injury model. Based on this model, the hemodynamic changes and arterial blood gas analysis after the burn-blast combined injury were measured to identify the cardiopulmonary system characteristics. In this research, RDX explosion and flame injury were used to develop a severe burn-blast injury animal model that was stable, close to reality, and easily controllable. The hemodynamic and arterial blood gas changes in the canine subjects after burn-blast injury changed distinctly from the burn and blast injuries. Blood pressure and cardiac output fluctuated, and the preload was significantly reduced, whereas the afterload significantly increased. Meanwhile, the oxygen saturation (SO2) decreased markedly with carbon dioxide partial pressure (PCO2), and lactic acid (Lac) rose, and oxygen partial pressure (PO2) reduced. These changes suggested that immediate clinical treatment is important during burn-blast injury both to stabilize cardiac function and supply blood volume and to reduce the vascular permeability, thereby preventing acute pneumonedema or other complications.

Computational research on lithium ion battery materials

NASA Astrophysics Data System (ADS)

Tang, Ping

Crystals of LiFePO4 and related materials have recently received a lot of attention due to their very promising use as cathodes in rechargeable lithium ion batteries. This thesis studied the electronic structures of FePO 4 and LiMPO4, where M=Mn, Fe, Co and Ni within the framework of density-functional theory. The first study compared the electronic structures of the LiMPO 4 and FePO4 materials in their electrochemically active olivine form, using the LAPW (linear augmented plane wave) method [1]. A comparison of results for various spin configurations suggested that the ferromagnetic configuration can serve as a useful approximation for studying general features of these systems. The partial densities of states for the LiMPO4 materials are remarkably similar to each other, showing the transition metal 3d states forming narrow bands above the O 2p band. By contrast, in absence of Li, the majority spin transition metal 3d states are well-hybridized with the O 2p band in FePO4. The second study compared the electronic structures of FePO4 in several crystal structures including an olivine, monoclinic, quartz-like, and CrVO4-like form [2,3]. For this work, in addition to the LAPW method, PAW (Projector Augmented Wave) [4], and PWscf (plane-wave pseudopotential) [5] methods were used. By carefully adjusting the computational parameters, very similar results were achieved for the three independent computational methods. Results for the relative stability of the four crystal structures are reported. In addition, partial densities of state analyses show qualitative information about the crystal field splittings and bond hybridizations and help rationalize the understanding of the electrochemical and stability properties of these materials.

Criteria predictive of limb viability at 1 year in patients with chronic severe ischemia--TcPO2 and demographic parameters.

PubMed

Chomard, D; Habault, P; Eveno, D; Le Lamer, S; Ledemeney, M; Haon, C

2000-09-01

Following an earlier study, the investigators sought to identify and define objective prognostic criteria of viability at 1 year of a limb with severe chronic ischemia. A study was undertaken in 116 patients (118 limbs) (74 men and 42 women), with a mean age of 71.9 years for men and 81.6 years for women. Static transcutaneous oxygen pressure (TcPO2) was measured with a verticalization sensitization test and inhalation of oxygen on JO and viability of the limb noted 1 year later. Logistic analysis was made of 13 oximetry parameters and two demographic parameters (age and gender). Results were analyzed in absolute terms and by tissue oxygenation ratio (TOR) (ratio between absolute TcPO2 at the foot and at a chest reference electrode). Six factors appeared to be prognostic factors of limb viability at 1 year, statistically significant at 6% according to threshold values: age, verticalization TcPO2, TcPO2 after 1 minute's inhalation of oxygen, TcPO2 after 4 minutes' inhalation of oxygen, and slope of TcPO2 and slope of TOR between 1 and 4 minutes' inhalation. A 1 year viability index integrating these criteria is suggested.

[Participation of nitric oxide and arachidonic acid metabolites via cytochrome - P450 in the regulation of arterial blood pressure].

PubMed

Sánchez-Mendoza, M Alicia; Martínez-Ayala, Sonia O; Hernández-Hernández, José A; Zúñiga-Sosa, Leonor; Pastelín-Hernández, Gustavo; Escalante-Acosta, Bruno A

2003-01-01

Nitric oxide and cytochrome P450 arachidonic acid metabolites participate in blood pressure regulation. The synthesis of these autacoids leads to arterial hypertension. However, it is not known whether there is an interaction between them. Therefore, we studied the modulatory effect of nitric oxide and cytochrome P450-arachidonic acid metabolites, their interaction on blood pressure, and the renal content of cytochrome P450. Male Wistar rats were divided: 1) control, 2) L-NAME (100 mg/kg/d p.o.), 3) L-NAME + SnCl2 (10 mg/kg/d i.p.), and 4) L-NAME + dexamethasone (1 mg/kg/d s.c.). We measured blood pressure and collected urine and blood for nitric oxide measurement. NO2 was quantified by HPLC. Blood pressure was: control, 97 +/- 7 mmHg; L-NAME, 151 +/- 4.6 mmHg; L-NAME + SnCl2, 133 +/- 3 mmHg, and L-NAME + dexamethasone 152 +/- 4.5 mmHg. Urine nitrite concentration was: 1) 1.832 +/- 0.32, 2) 1.031 +/- 0.23, 3) 1.616 +/- 0.33, and 4) 1.244 +/- 0.33 mumol/mL, while the concentration in blood was: 1) 0.293 +/- 0.06, 2) 0.150 +/- 0.05, 3) 0.373 +/- 0.13, and 4) 0.373 +/- 0.07 mumol/mL. L-NAME + SnCl2 decreased cytochrome P450 renal content, and L-NAME + dexamethasone showed a similar response. In conclusion, both, nitric oxide and CYP-arachidonic acid metabolites play a role in the regulation of blood pressure. Nitric oxide also partially regulates renal cytochrome P450 content.

Bromelain ameliorates the wound microenvironment and improves the healing of firearm wounds.

PubMed

Wu, Si-Yu; Hu, Wei; Zhang, Bo; Liu, Shuai; Wang, Jian-Min; Wang, Ai-Min

2012-08-01

In a previous study, we proposed a new therapy using topical bromelain as a supplement to simple wound-track incision for the debridement of firearm wounds. This enzymatic debridement greatly simplified the management of high-velocity gunshot wounds in a pig model, and bromelain was confirmed to improve wound healing. The purpose of the present study was to investigate the effect of bromelain on the microenvironment of firearm wounds. Sixteen Chinese landrace pigs wounded by high-velocity projectiles were divided randomly into four groups: wound incision (group I), incision + bromelain (group IB), wound excision (group E), and control. Blood perfusion, oxygen partial pressure (pO(2)), and the content of tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β in wound-track tissue were measured. Wound healing was also noted. The recovery of blood perfusion in tissue and pO(2) in wound tracks was significantly more rapid in group IB and group E than in group I and control. The tissue level of TNF-α was significantly lower in group IB than in group I and control 48 h and 72 h post-wounding, and was lower than in group E 48 h post-wounding. The tissue level of TGF-β in group IB was sustained at a significantly higher level than in the other three groups. Wound healing time was also shorter in group IB. Enzymatic debridement using topical bromelain in incised wound tracks accelerates the recovery of blood perfusion, pO(2) in wound tissue, controls the expression of TNF-α and raises the expression of TGF-β. Copyright © 2012 Elsevier Inc. All rights reserved.

Respiratory properties of blood and arterial blood gases in the tegu lizard: effects of temperature and hypercapnia.

PubMed

Wood, S C; Glass, M L; Andersen, N A; Heisler, N

1987-01-01

The effects of body temperature and hypercapnia (7% inspired CO2) on arterial blood gases, plasma pH, and the characteristics of the blood oxygen dissociation curve were determined in Tegu lizards (Tupinambis nigropunctatus). Arterial pH fell from 7.59 to 7.50 when body temperature was increased from 25 to 35 degrees C. The pH/temperature coefficient (delta pH/delta t = -0.009 U/degrees C) was half of that predicted on the basis of 'constant relative alkalinity' and the alphastat hypothesis. The fall in plasma pH resulted from a decrease in plasma [HCO3-], and a rise in plasma Pco2. The O2 affinity of Tegu blood, expressed by the partial pressure at half saturation (P50), decreased with temperature in vitro from 42.3 to 49.6 torr at pH 7.4. The apparent enthalpy (delta H = -3.1 kcal/mol) is about 1/4 of that of human blood. In vivo, the arterial blood oxygen saturation decreased from 89% at 25 degrees to 82% at 35 degrees C. Arterial Po2 increased from 61 to 71 torr as expected from the right-shift of the oxygen dissociation curve. During environmental hypercapnia (7% CO2, 21% O2, 72% N2 inspired concentrations), arterial pH decreased to 7.28. Arterial O2 saturation remained constant and arterial Po2 increased from 61 to 85 torr due to the right-shift of the oxygen dissociation curve. The comparatively small effect of changes in temperature on the oxygen affinity of Tegu blood (directly according to the delta H value, and indirectly via changes in blood pH) results in a relatively small right shift of the oxygen dissociation curve, and accordingly in relatively high arterial and tissue Po2 values also at higher temperatures.

USE IT OR LOSE IT: EAT AND EXERCISE DURING RADIOTHERAPY OR CHEMORADIOTHERAPY FOR PHARYNGEAL CANCERS

PubMed Central

Hutcheson, Katherine A.; Bhayani, Mihir K.; Beadle, Beth M.; Gold, Kathryn A.; Shinn, Eileen H.; Lai, Stephen Y.; Lewin, Jan

2014-01-01

Objective Proactive swallowing therapy promotes ongoing use of the swallowing mechanism during radiotherapy through 2 goals: eat and exercise. The purpose of this study was to evaluate the independent effects of maintaining oral intake throughout treatment and preventive swallowing exercise. Design Retrospective observational study. Setting The University of Texas MD Anderson Cancer Center, Houston. Patients The study included 497 patients treated with definitive radiotherapy (RT) or chemoradiation (CRT) for pharyngeal cancer (458 oropharynx, 39 hypopharynx) between 2002 and 2008. Main Outcome Measures Swallowing-related endpoints were: final diet after RT/CRT and length of gastrostomy-dependence. Primary independent variables included per oral (PO) status at the end of RT/CRT (nothing per oral [NPO], partial PO, 100% PO) and swallowing exercise adherence. Multiple linear regression and ordered logistic regression models were analyzed. Results At the conclusion of RT/CRT, 131 (26%) were NPO, 74% were PO (167 [34%] partial, 199 [40%] full). Fifty-eight percent (286/497) reported adherence to swallowing exercises. Maintenance of PO intake during RT/CRT and swallowing exercise adherence were independently associated (p<0.05) with better long-term diet after RT/CRT and shorter length of gastrostomy dependence in models adjusted for tumor and treatment burden. Conclusions Data indicate independent, positive associations between maintenance of PO intake throughout RT/CRT and swallowing exercise adherence with long-term swallowing outcomes. Patients who either eat or exercise fare better than those who do neither. Patients who both eat and exercise have the highest return to a regular diet and shortest gastrostomy dependence. PMID:24051544

The Toxicity of Inhaled Sulphur Mustard

DTIC Science & Technology

2012-03-01

Pulse oximetry Mean arterial pressure Central venous pressure Blood Chemistry (arterial and venous ) pH pO2 pCO2 Sodium Potassium Calcium...Cardiovascular Parameters − CFI – Cardiac Function Index − CO – Cardiac Output − CvO2 – Mixed Venous Oxygenation − CVP – Central Venous Pressure...Data are expressed as mean ± SEM. Changes in central venous pressure following exposure to HD: HD controls () and HD + NAC (). Data are

Thermodynamic evaluation of oxygen behavior in Ti powder deoxidized by Ca reductant

NASA Astrophysics Data System (ADS)

Kim, Sun-Joong; Oh, Jung-Min; Lim, Jae-Won

2016-07-01

To produce low oxygen Ti powder of less than 1000 mass ppm, commercial Ti powder was deoxidized by two types of Ca reductants: a solid Ca and a Ca vapor. Compared with the iso-oxygen partial pressure in the Ti-O binary phase diagram, the PO2 in the raw Ti powder increased with temperature compared to the reduction reaction of Ca. Therefore, the O2 content in the Ti powder decreased as the deoxidation temperature increased from 873 K, showing a local minima at 1273 K. The oxygen concentration at 1373 K was greater than that at 1273 K because the oxygen solubility of the Ti powder was increased by the equilibrium relation between Ca and CaO. On the basis of the thermodynamic assessment, the deoxidation of Ti powder can be improved by increasing the temperature and lowering the oxygen solubility with the saturation of CaO.

Preparation and Electrochemical Properties of Li3V2(PO4)3−xBrx/Carbon Composites as Cathode Materials for Lithium-Ion Batteries

PubMed Central

Cao, Xiaoyu; Mo, Lulu; Zhu, Limin; Xie, Lingling

2017-01-01

Li3V2(PO4)3−xBrx/carbon (x = 0.08, 0.14, 0.20, and 0.26) composites as cathode materials for lithium-ion batteries were prepared through partially substituting PO43− with Br−, via a rheological phase reaction method. The crystal structure and morphology of the as-prepared composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and electrochemical properties were evaluated by charge/discharge cycling and electrochemical impedance spectroscopy (EIS). XRD results reveal that the Li3V2(PO4)3−xBrx/carbon composites with solid solution phase are well crystallized and have the same monoclinic structure as the pristine Li3V2(PO4)3/carbon composite. It is indicated by SEM images that the Li3V2(PO4)3−xBrx/carbon composites possess large and irregular particles, with an increasing Br− content. Among the Li3V2(PO4)3−xBrx/carbon composites, the Li3V2(PO4)2.86Br0.14/carbon composite shows the highest initial discharge capacity of 178.33 mAh·g−1 at the current rate of 30 mA·g−1 in the voltage range of 4.8–3.0 V, and the discharge capacity of 139.66 mAh·g−1 remains after 100 charge/discharge cycles. Even if operated at the current rate of 90 mA·g−1, Li3V2(PO4)2.86Br0.14/carbon composite still releases the initial discharge capacity of 156.57 mAh·g−1, and the discharge capacity of 123.3 mAh·g−1 can be maintained after the same number of cycles, which is beyond the discharge capacity and cycleability of the pristine Li3V2(PO4)3/carbon composite. EIS results imply that the Li3V2(PO4)2.86Br0.14/carbon composite demonstrates a decreased charge transfer resistance and preserves a good interfacial compatibility between solid electrode and electrolyte solution, compared with the pristine Li3V2(PO4)3/carbon composite upon cycling. PMID:28336886

Silver Vanadium Phosphorous Oxide, Ag(2)VO(2)PO(4): Chimie Douce Preparation and Resulting Lithium Cell Electrochemistry.

PubMed

Kim, Young Jin; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

2011-08-15

Recently, we have shown silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4), SVPO) to be a promising cathode material for lithium based batteries. Whereas the first reported preparation of SVPO employed an elevated pressure, hydrothermal approach, we report herein a novel ambient pressure synthesis method to prepare SVPO, where our chimie douce preparation is readily scalable and provides material with a smaller, more consistent particle size and higher surface area relative to SVPO prepared via the hydrothermal method. Lithium electrochemical cells utilizing SVPO cathodes made by our new process show improved power capability under constant current and pulse conditions over cells containing cathode from SVPO prepared via the hydrothermal method.

A gel aging effect in the synthesis of open-framework gallium phosphates: structure solution and solid-state NMR of a large-pore, open-framework material† †Electronic supplementary information (ESI) available. CCDC 1577782 and 1577783. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7dt03709k

PubMed Central

Broom, Lucy K.; Clarkson, Guy J.; Guillou, Nathalie; Hooper, Joseph E.; Dawson, Daniel M.; Tang, Chiu C.; Ashbrook, Sharon E.

2017-01-01

The templated zeolite-analogue GaPO-34 (CHA structure type) crystallises from a gel precursor Ga2O3 : 2H3PO4 : 1HF : 1.7SDA : 70H2O (where SDA = structure directing agent), treated hydrothermally for 24 hours at 170 °C using either pyridine or 1-methylimizadole as SDA and one of either poorly crystalline ε-Ga2O3 or γ-Ga2O3 as gallium precursor. If the same gels are stirred for periods shorter than 2 hours but treated under identical hydrothermal conditions, then a second phase crystallises, free of GaPO-34. If β-Ga2O3 is used as a reagent only the second phase is found to crystallise, irrespective of gel aging time. The competing phase, which we denote GaPO-34A, has been structurally characterised using synchrotron powder X-ray diffraction for the pyridine material, GaPO-34A(pyr), and using single-crystal X-ray diffraction for the 1-methylimiazole material, GaPO-34A(mim). The structure of GaPO-34A(pyr), P1, a = 10.22682(6) Å, b = 12.09585(7) Å, c = 13.86713(8) Å, α = 104.6531(4)°, β = 100.8111(6)°, γ = 102.5228(6)°, contains 7 unique gallium sites and 6 phosphorus sites, with empirical formula [Ga7P6O24(OH)2F3(H2O)2]·2(C5NH6). GaPO-34A(mim) is isostructural but is modelled as a half volume unit cell, P1, a = 5.0991(2) Å, b = 12.0631(6) Å, c = 13.8405(9) Å, α = 104.626(5)°, β = 100.346(5)°, γ = 101.936(4)°, with a gallium and a bridging fluoride partially occupied and two partially occupied SDA sites. Solid-state 31P and 71Ga NMR spectroscopy confirms the structural complexity of GaPO-34A with signals resulting from overlapping lineshapes from multiple Ga and P sites, while 1H and 13C solid-state NMR spectra confirm the presence of the protonated SDA and provide evidence for disorder in the SDA. The protonated SDA is located in 14-ring one-dimensional channels with hydrogen bonding deduced from the SDA nitrogens to framework oxygen distances. Upon thermal treatment to investigate SDA removal, structure collapse occurs, which may be due the large number of bridging hydroxides and fluorides in the as-made material, and the unequal amounts of gallium and phosphorus present. PMID:29171855

Technology development for phosphoric acid fuel cell powerplant, phase 2

NASA Technical Reports Server (NTRS)

Christner, L.

1979-01-01

A technique for producing an acid inventory control member by spraying FEP onto a partially screened carbon paper backing is discussed. Theoretical analysis of the acid management indicates that the vapor composition of 103% H3PO4 is approximately 1.0 ppm P4O10. An SEM evaluation of corrosion resistance of phenolic resins and graphite/phenolic resin composites in H3PO4 at 185 C shows specific surface etching. Carbonization of graphite/phenolic bipolar plates is achieved without blistering.

Blood oxygen binding in hypoxaemic calves.

PubMed

Cambier, Carole; Clerbaux, Thierry; Detry, Bruno; Marville, Vincent; Frans, Albert; Gustin, Pascal

2002-01-01

Blood oxygen transport and tissue oxygenation were studied in 28 calves from the Belgian White and Blue breed (20 healthy and 8 hypoxaemic ones). Hypoxaemic calves were selected according to their high respiratory frequency and to their low partial oxygen pressure (PaO2) in the arterial blood. Venous and arterial blood samples were collected, and 2,3-diphosphoglycerate, adenosine triphosphate, chloride, inorganic phosphate and hemoglobin concentrations, and pH, PCO, and PO2 were determined. An oxygen equilibrium curve (OEC) was measured in standard conditions, for each animal. The arterial and venous OEC were calculated, taking body temperature, pH and PCO2 values in arterial and venous blood into account. The oxygen exchange fraction (OEF%), corresponding to the degree of blood desaturation between the arterial and the venous compartments, and the amount of oxygen released at the tissue level by 100 mL of blood (OEF Vol%) were calculated from the arterial and venous OEC combined with the PO2 and hemoglobin concentration. In hypoxaemic calves investigated in this study, the hemoglobin oxygen affinity, measured under standard conditions, was not modified. On the contrary, in vivo acidosis and hypercapnia induced a decrease in the hemoglobin oxygen affinity in arterial blood, which combined to the decrease in PaO2 led to a reduced hemoglobin saturation degree in the arterial compartment. However, this did not impair the oxygen exchange fraction (OEF%), since the hemoglobin saturation degree in venous blood was also diminished.

[INVITED] Laser gas assisted treatment of Ti-alloy: Analysis of surface characteristics

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Ali, H.; Karatas, C.

2016-04-01

Laser gas assisted treatment of Ti6Al4V alloy surface is carried out and nitrogen/oxygen mixture with partial pressure of PO2/PN2=1/3 is introduced during the surface treatment process. Analytical tools are used to characterize the laser treated surfaces. The fracture toughness at the surface and the residual stress in the surface region of the laser treated layer are measured. Scratch tests are carried out to determine the friction coefficient of the treated surface. It is found that closely spaced regular laser scanning tracks generates a self-annealing effect in the laser treated layer while lowering the stress levels in the treated region. Introducing high pressure gas mixture impingement at the surface results in formation of oxide and nitride species including, TiO, TiO2, TiN and TiOxNy in the surface region. A dense layer consisting of fine size grains are formed in the surface region of the laser treated layer, which enhances the microhardness at the surface. The fracture toughness reduces after the laser treatment process because of the microhardness enhancement at the surface. The residual stress formed is comprehensive, which is in the order of -350 MPa.

Specifications of a continual reassessment method design for phase I trials of combined drugs†

PubMed Central

Wages, Nolan A.; Conaway, Mark R.

2013-01-01

In studies of combinations of agents in phase I oncology trials, the dose–toxicity relationship may not be monotone for all combinations, in which case the toxicity probabilities follow a partial order. The continual reassessment method for partial orders (PO-CRM) is a design for phase I trials of combinations that leans upon identifying possible complete orders associated with the partial order. This article addresses some practical design considerations not previously undertaken when describing the PO-CRM. We describe an approach in choosing a proper subset of possible orderings, formulated according to the known toxicity relationships within a matrix of combination therapies. Other design issues, such as working model selection and stopping rules, are also discussed. We demonstrate the practical ability of PO-CRM as a phase I design for combinations through its use in a recent trial designed at the University of Virginia Cancer Center. PMID:23729323

Partial Pressures of Te2 and Thermodynamic Properties of Ga-Te System

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

2001-01-01

The partial pressures of Te2 in equilibrium with Ga(1-x)Te(x) samples were measured by optical absorption technique from 450 to 1100 C for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te, and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's Law constants. The partial pressures of Te2 in equilibrium with the GaTe(s) and Ga2Te3(s)compounds, or the so-called three-phase curves, were established. These partial pressure data imply the existence of the Ga3Te4(s) compound. From the partial pressures of Te2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonable well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te2. These data agree well with most of the previous results. The possible reason for the high activity of Te measured for x less than 0.60 is discussed.

Long-term sedimentary recycling of rare sulphur isotope anomalies.

PubMed

Reinhard, Christopher T; Planavsky, Noah J; Lyons, Timothy W

2013-05-02

The accumulation of substantial quantities of O2 in the atmosphere has come to control the chemistry and ecological structure of Earth's surface. Non-mass-dependent (NMD) sulphur isotope anomalies in the rock record are the central tool used to reconstruct the redox history of the early atmosphere. The generation and initial delivery of these anomalies to marine sediments requires low partial pressures of atmospheric O2 (p(O2); refs 2, 3), and the disappearance of NMD anomalies from the rock record 2.32 billion years ago is thought to have signalled a departure from persistently low atmospheric oxygen levels (less than about 10(-5) times the present atmospheric level) during approximately the first two billion years of Earth's history. Here we present a model study designed to describe the long-term surface recycling of crustal NMD anomalies, and show that the record of this geochemical signal is likely to display a 'crustal memory effect' following increases in atmospheric p(O2) above this threshold. Once NMD anomalies have been buried in the upper crust they are extremely resistant to removal, and can be erased only through successive cycles of weathering, dilution and burial on an oxygenated Earth surface. This recycling results in the residual incorporation of NMD anomalies into the sedimentary record long after synchronous atmospheric generation of the isotopic signal has ceased, with dynamic and measurable signals probably surviving for as long as 10-100 million years subsequent to an increase in atmospheric p(O2) to more than 10(-5) times the present atmospheric level. Our results can reconcile geochemical evidence for oxygen production and transient accumulation with the maintenance of NMD anomalies on the early Earth, and suggest that future work should investigate the notion that temporally continuous generation of new NMD sulphur isotope anomalies in the atmosphere was likely to have ceased long before their ultimate disappearance from the rock record.

Highly selective colorimetric and electrochemical sensing of iron (III) using Nile red functionalized graphene film.

PubMed

Sadak, Omer; Sundramoorthy, Ashok K; Gunasekaran, Sundaram

2017-03-15

We report a highly selective method for identification and detection of iron (III) (ferric iron, Fe 3+ ) using Nile red (NR) as a complexing agent. Fe 3+ preferentially binds with NR in dimethylformamide (DMF)/water (1:1) solution over other cations such as Fe 2+ , Cu 2+ , Pb 2+ , Hg 2+ , Mn 2+ , Ni 2+ , Zn 2+ , Co 2+ and Cd 2+ at room temperature. In the presence of Fe 3+ , the color of NR solution changes from purple to dark brown, which is detectable with bare eyes. Using UV-vis spectroscopy, we could measure the amount of Fe 3+ in the sample solution by monitoring changes in absorption from 540 to 580nm; the linear range and the limit of detection are 30-1000µM and 24.9µM, respectively. Taking advantage of the NR selectivity, we treated partially oxidized graphene sheets (po-Gr) with NR to obtain po-Gr-NR dispersion by ultrasonication. The NR-treated po-Gr flakes (po-Gr-NR) were characterized by UV-vis, FT-IR, and Raman spectroscopies and FE-SEM, which indicated attachment of NR on po-Gr sheets. The po-Gr-NR hybrid film deposited glassy carbon electrode (po-Gr-NR/GCE) served as the Fe 3+ sensor. Differential pulse voltammetry was used to investigate the detection of Fe 3+ in 0.05M HCl+0.05M KCl solution. The linear range and the limit of detection of Fe 3+ were from 37.5nM to 21.53µM and 18.7nM, respectively. Furthermore, this sensor was successfully used to measure Fe 3+ content in red wine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

A prospective randomized study of systemic inflammation and immune response after laparoscopic nissen fundoplication performed with standard and low-pressure pneumoperitoneum.

PubMed

Schietroma, Mario; Carlei, Francesco; Cecilia, Emanuela M; Piccione, Federica; Sista, Federico; De Vita, Fabiola; Amicucci, Gianfranco

2013-04-01

The aim of this study was to compare changes in the systemic inflammation and immune response in the early postoperative (p.o.) period after laparoscopic Nissen fundoplication (LNF) was performed with standard-pressure and low-pressure carbon dioxide pneumoperitoneum. We studied 68 patients with documented gastroesophageal reflux disease and who underwent a LNF: 35 using standard-pressure (12 to 14 mmHg) and 33 low-pressure (6 to 8 mmHg) pneumoperitoneum. White blood cells, peripheral lymphocytes subpopulation, human leukocyte antigen-DR, neutrophil elastase, interleukin (IL)-6 and IL-1, and C-reactive protein were investigated. A significantly higher concentration of neutrophil elastase, IL-6 and IL-1, and C-reactive protein was detected postoperatively in the standard-pressure group of patients in comparison with the low-pressure group (P<0.05). A statistically significant change in human leukocyte antigen-DR expression was recorded p.o. at 24 hours, as a reduction of this antigen expressed on monocyte surface in patients from standard group; no changes were noted in low-pressure group patients (P<0.05). This study demonstrated that reducing the pressure of the pneumoperitoneum to 6 to 8 mm Hg during LNF is reduced p.o. inflammatory response and avoided p.o. immunosuppression.

Synthesis, characterization, vibrational spectroscopy, and factor group analysis of partially metal-doped phosphate materials

NASA Astrophysics Data System (ADS)

Sronsri, Chuchai; Boonchom, Banjong

2018-04-01

A simple precipitating method was used to synthesize effectively a partially metal-doped phosphate hydrate (Mn0.9Mg0.1HPO4·3H2O), whereas the thermal decomposition process of the above hydrate precursor was used to obtain Mn1.8Mg0.2P2O7 and LiMn0.9Mg0.1PO4 compounds under different conditions. To separate the overlapping thermal decomposition peak, a deconvolution technique was used, and the separated peak was applied to calculate the water content. The factor group splitting analysis was used to exemplify their vibrational spectra obtained from normal vibrations of HPO42-, H2O, P2O74- and PO43- functional groups. Further, the deconvoluted bending mode of water was clearly observed. Mn0.9Mg0.1HPO4·3H2O was observed in the orthorhombic crystal system with the space group of Pbca (D2h15). The formula units per unit cell were found to be eight (Z = 8), and the site symmetric type of HPO42- was observed as Cs. For the HPO42- unit, the correlation filed splitting analysis of type C3v - Cs - D2h15 was calculated and had 96 internal modes, whereas H2O in the above hydrate was symbolized as C2v - Cs - D2h15 and had 24 modes. The symbol C2v - Cs - C2h3 was used for the correlation filed splitting analysis of P2O74- in Mn1.8Mg0.2P2O7 (monoclinic, C2/m (C2h3), Z = 2, and 42 modes). Finally, the symbol Td - Cs - D2h16 was used for the correlation filed splitting analysis of PO43- in LiMn0.9Mg0.1PO4 (orthorhombic, Pnma (D2h16), Z = 4, and 36 modes).

Pressure leaching of chalcopyrite concentrate

NASA Astrophysics Data System (ADS)

Aleksei, Kritskii; Kirill, Karimov; Stanislav, Naboichenko

2018-05-01

The results of chalcopyrite concentrate processing using low-temperature and high-temperature sulfuric acid pressure leaching are presented. A material of the following composition was used, 21.5 Cu, 0.1 Zn, 0.05 Pb, 0.04 Ni, 26.59 S, 24.52 Fe, 16.28 SiO2 (in wt.%). The influence of technological parameters on the degree of copper and iron extraction into the leach solution was studied in the wide range of values. The following conditions were suggested as the optimal for the high-temperature pressure leaching: t = 190 °C, PO2 = 0.5 MPa, CH2SO4 = 15 g/L, L:S = 6:1. At the mentioned parameters, it is possible to extract at least 98% Cu from concentrate into the leaching solution during 100 minutes. The following conditions were suggested as optimal for the low-temperature pressure leaching: t = 105 °C, PO2 = 1.3-1.5 MPa, CH2SO4 = 90 g/L, L:S = 10:1. At the mentioned parameters, it is possible to extract up to 83% Cu from the concentrate into the leach solution during 300-360 minutes.

Fast and highly efficient SO2 capture by TMG immobilized on hierarchical micro-meso-macroporous AlPO-5/cordierite honeycomb ceramic materials.

PubMed

Xu, Jin; Zha, Xiaoling; Wu, Yumei; Ke, Qingping; Yu, Weifang

2016-05-11

SO2 capacity of the obtained TMG-AlPO-5/cordierite honeycomb ceramic (CHC) adsorbent was measured to be 1.13 mol per mol TMG. More importantly, compared with literature reported supported ionic liquids, it is featured by a significantly improved adsorption rate (t0.9 reduced from >30 min to ∼0.1 min) and negligible pressure drop.

Chemically grafted carbon-coated LiFePO4 using diazonium chemistry

NASA Astrophysics Data System (ADS)

Delaporte, Nicolas; Perea, Alexis; Amin, Ruhul; Zaghib, Karim; Bélanger, Daniel

2015-04-01

The effect of surface functionalization of aminophenyl and bromophenyl groups on carbon-coated LiFePO4 and the electrochemical properties of composite electrode containing these materials are reported. The functionalization was performed by spontaneous reduction of the corresponding in situ generated diazonium ions. The resulting chemically grafted LiFePO4/C materials were characterized by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) to confirm the presence of the surface organic species. XRD analyses indicated the cathode material was partially oxidized. Thermogravimetric and elemental analyses revealed the loading of grafted molecules was between 0.2 and 1.1 wt.% depending on the reaction conditions. Interestingly, the electrochemical performances of the modified LiFePO4/C are not adversely affected by the presence of either aminophenyl and bromophenyl groups at the carbon surface, and in fact the grafted LiFePO4/C displayed slightly superior discharge capacity at the highest C rate investigated for a low loading of organic molecules.

Co11Li[(OH)5O][(PO3OH)(PO4)5], a Lithium-Stabilized, Mixed-Valent Cobalt(II,III) Hydroxide Phosphate Framework.

PubMed

Ludwig, Jennifer; Geprägs, Stephan; Nordlund, Dennis; Doeff, Marca M; Nilges, Tom

2017-09-18

A new metastable phase, featuring a lithium-stabilized mixed-valence cobalt(II,III) hydroxide phosphate framework, Co 11.0(1) Li 1.0(2) [(OH) 5 O][(PO 3 OH)(PO 4 ) 5 ], corresponding to the simplified composition Co 1.84(2) Li 0.16(3) (OH)PO 4 , is prepared by hydrothermal synthesis. Because the pH-dependent formation of other phases such as Co 3 (OH) 2 (PO 3 OH) 2 and olivine-type LiCoPO 4 competes in the process, a pH value of 5.0 is crucial for obtaining a single-phase material. The crystals with dimensions of 15 μm × 30 μm exhibit a unique elongated triangular pyramid morphology with a lamellar fine structure. Powder X-ray diffraction experiments reveal that the phase is isostructural with the natural phosphate minerals holtedahlite and satterlyite, and crystallizes in the trigonal space group P31m (a = 11.2533(4) Å, c = 4.9940(2) Å, V = 547.70(3) Å 3 , Z = 1). The three-dimensional network structure is characterized by partially Li-substituted, octahedral [M 2 O 8 (OH)] (M = Co, Li) dimer units which form double chains that run along the [001] direction and are connected by [PO 4 ] and [PO 3 (OH)] tetrahedra. Because no Li-free P31m-type Co 2 (OH)PO 4 phase could be prepared, it can be assumed that the Li ions are crucial for the stabilization of the framework. Co L-edge X-ray absorption spectroscopy demonstrates that the cobalt ions adopt the oxidation states +2 and +3 and hence provides further evidence for the incorporation of Li in the charge-balanced framework. The presence of three independent hydroxyl groups is further confirmed by infrared spectroscopy. Magnetization measurements imply a paramagnetic to antiferromagnetic transition at around T = 25 K as well as a second transition at around 9-12 K with a ferromagnetic component below this temperature. The metastable character of the phase is demonstrated by thermogravimetric analysis and differential scanning calorimetry, which above 558 °C reveal a two-step decomposition to CoO, Co 3 (PO 4 ) 2 , and olivine-type LiCoPO 4 with release of water and oxygen.

Nitric oxide bioavailability modulates the dynamics of microvascular oxygen exchange during recovery from contractions.

PubMed

Hirai, D M; Copp, S W; Ferreira, L F; Musch, T I; Poole, D C

2010-10-01

lowered microvascular PO(2) (PO(2) mv) during the exercise off-transient likely impairs muscle metabolic recovery and limits the capacity to perform repetitive tasks. The current investigation explored the impact of altered nitric oxide (NO) bioavailability on PO(2) mv during recovery from contractions in healthy skeletal muscle. We hypothesized that increased NO bioavailability (sodium nitroprusside: SNP) would enhance PO(2) mv and speed its recovery kinetics while decreased NO bioavailability (l-nitro arginine methyl ester: l-NAME) would reduce PO(2) mv and slow its recovery kinetics.   PO(2) mv was measured by phosphorescence quenching during transitions (rest-1 Hz twitch-contractions for 3 min-recovery) in the spinotrapezius muscle of Sprague-Dawley rats under SNP (300 microm), Krebs-Henseleit (CONTROL) and l-NAME (1.5 mm) superfusion conditions. relative to recovery in CONTROL, SNP resulted in greater overall microvascular oxygenation as assessed by the area under the PO(2) mv curve (PO(2 AREA) ; 3471 ± 292 mmHg s; SNP: 4307 ± 282 mmHg s; P < 0.05) and faster off-kinetics as evidenced by the mean response time (MRToff; 60.2 ± 6.9 s; SNP: 34.8 ± 5.7 s; P < 0.05), whereas l-NAME produced lower PO(2 AREA) (2339 ± 444 mmHg s; P < 0.05) and slower MRToff (86.6 ± 14.5s; P < 0.05). no bioavailability plays a key role in determining the matching of O(2) delivery-to-O(2) uptake and thus the upstream O(2) pressure driving capillary-myocyte O(2) flux (i.e. PO(2) mv) following cessation of contractions in healthy skeletal muscle. Additionally, these data support a mechanistic link between reduced NO bioavailability and prolonged muscle metabolic recovery commonly observed in ageing and diseased populations. © 2010 The Authors. Journal compilation © 2010 Scandinavian Physiological Society.

Synthesis and Performance of LiFe1-xMnxPO4 in Lithium-ion Battery

NASA Astrophysics Data System (ADS)

Bazzi, Khadije; Nazri, Maryam; Vaishnava, Prem; Naik, Vaman; Nazri, Gholam-Abbas; Naik, Ratna

2013-03-01

Olivine-type lithium transition metal phosphates (i.e. LiFePO4) have been intensively investigated as promising electrode materials for rechargeable lithium-ion batteries. There have been attempts to improve energy density and voltage quality of phosphate based electrode. In this study, we have partially substituted FeII/FeIII redox center with MnII/MnIII in LiFePO4 that provides over 600 mV higher voltage. We prepared various compositions of LiFe1-xMnxPO4 (x =0, 0.2, 0.4, 0.6, 0.8 and 1) between the two end members (LiFePO4 - LiMnPO4) . Due to intrinsic low electronic conductivity of lithium transition metal phosphates, we coat these materials with a uniform conductive carbon through a unique sol-gel process developed in our laboratory. In addition, we made a composite of the carbon coated phosphate with carbon nano-tubes to develop a highly conductive matrix electrode. We report the materials structure, morphology, electrical conductivity and electrochemical performances of LiFe1-xMnxPO4 using XRD, Raman spectroscopy, SEM, TEM, XPS, electrical conductivity and galvanostatic charge/discharge measurements.

Ocular oxygen consumption during vitreoperfusion in the cat.

PubMed

Blair, N P

2000-01-01

Little is known about the total ocular oxygen consumption rate (QO2) in human diseases. Reductions in QO2 may indicate the amount of tissue loss produced by conditions such as retinal ischemia. We sought a method to estimate QO2 that eventually could be used in patients during vitrectomy surgery. We performed vitreoperfusion (perfusion of the vitreous cavity after vitrectomy) in 22 cat eyes with no ocular blood flow. The solution contained nutrients and a high partial pressure of oxygen (PO2). In 8 eyes we placed an oxygen electrode on the sclera, choroid, or outer retina to evaluate oxygen delivery from the vitreoperfusion solution (group 1). In 8 eyes the retinas were undisturbed (group 2), and in 6 eyes we excised the retinas (group 3). In groups 2 and 3 we estimated QO2 from the temporal decline of PO2 in the vitreoperfusion solution according to a pharmacokinetic model. Group 1 demonstrated oxygenation of the entire retina. The means and standard deviations of QO2 were 3.2 +/- 0.8 and 0.4 +/- 0.7 microL/min in groups 2 and 3, respectively, the difference being the retinal contribution, 88%. In group 2, metabolism accounted for an average of 82% of the oxygen loss from the vitreoperfusion solution, whereas flow and diffusion accounted for 13% and 5%, respectively. Ocular oxygen consumption can be estimated by means of vitreoperfusion. Further developments may allow measurements in patients during vitreous surgery to clarify the pathophysiology of their diseases and assess the amount of retinal tissue that has been lost.

Enhanced thermal and structural properties of partially phosphorylated polyvinyl alcohol - Aluminum phosphate (PPVA-Alpo4) nanocomposites with aluminium nitrate source

NASA Astrophysics Data System (ADS)

Saat, Asmalina Mohamed; Johan, Mohd Rafie

2017-12-01

Synthesis of AlPO4 nanocomposite depends on the ratio of aluminum to phosphate, method of synthesis and the source for aluminum and phosphate source used. Variation of phosphate and aluminum source used will form multiple equilibria reactions and affected by ions variability and concentration, stoichiometry, temperature during reaction process and especially the precipitation pH. Aluminum nitrate was used to produce a partially phosphorylated poly vinyl alcohol-aluminum phosphate (PPVA-AlPO4) nanocomposite with various nanoparticle shapes, structural and properties. Synthesis of PPVA-AlPO4 nanocomposite with aluminum nitrate shows enhancement of thermal and structural in comparison with pure PVA and modified PPVA. Thermogravimetric (TGA) analysis shows that the weight residue of PPVA-AlPO4 composite was higher than PPVA and PVA. X-ray diffraction (XRD) pattern of PVA shows a single peak broadening after the addition of phosphoric acid. Meanwhile, XRD pattern of PPVA-AlPO4 demonstrates multiple phases of AlPO4 in the nanocomposite. Field Emission Scanning Electron Microscopy (FESEM) confirmed the existence of multiple geometrical phases and nanosize of spherical particles.

Thermocouple psychrometry

USGS Publications Warehouse

Andraski, Brian J.; Scanlon, Bridget R.; Dane, Jacob H.; Topp, G. Clarke

2002-01-01

Thermocouple psychrometry is a technique that infers the water potential of the liquid phase of a sample from measurements within the vapor phase that is in equilibrium with the sample. The theoretical relation between water potential of the liquid phase and relative humidity of the vapor phase is given by the Kelvin equation Ψ = energy/volume = (RT/Vw) ln(p/po) [3.2.3–1]where ψ is water potential (sum of matric and osmotic potential, MPa), R is the universal gas constant (8.314 × 10-6 MJ mol-1 K-1), T is temperature (K), Vw is molar volume of water (1.8 × 10-5 m3 mol-1), and p/po is relative humidity expressed as a fraction where p is actual vapor pressure of air in equilibrium with the liquid phase (MPa) and po is saturation vapor pressure (MPa) at T.

In vivo administration of calpeptin attenuates calpain activation and cardiomyocyte loss in pressure-overloaded feline myocardium

PubMed Central

Mani, Santhosh K.; Shiraishi, Hirokazu; Balasubramanian, Sundaravadivel; Yamane, Kentaro; Chellaiah, Meenakshi; Cooper, George; Banik, Naren; Zile, Michael R.; Kuppuswamy, Dhandapani

2008-01-01

Calpain activation is linked to the cleavage of several cytoskeletal proteins and could be an important contributor to the loss of cardiomyocytes and contractile dysfunction during cardiac pressure overload (PO). Using a feline right ventricular (RV) PO model, we analyzed calpain activation during the early compensatory period of cardiac hypertrophy. Calpain enrichment and its increased activity with a reduced calpastatin level were observed in 24- to 48-h-PO myocardium, and these changes returned to basal level by 1 wk of PO. Histochemical studies in 24-h-PO myocardium revealed the presence of TdT-mediated dUTP nick-end label (TUNEL)-positive cardiomyocytes, which exhibited enrichment of calpain and gelsolin. Biochemical studies showed an increase in histone H2B phosphorylation and cytoskeletal binding and cleavage of gelsolin, which indicate programmed cardiomyocyte cell death. To test whether calpain inhibition could prevent these changes, we administered calpeptin (0.6 mg/kg iv) by bolus injections twice, 15 min before and 6 h after induction of 24-h PO. Calpeptin blocked the following PO-induced changes: calpain enrichment and activation, decreased calpastatin level, caspase-3 activation, enrichment and cleavage of gelsolin, TUNEL staining, and histone H2B phosphorylation. Although similar administration of a caspase inhibitor, N-benzoylcarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VD-fmk), blocked caspase-3 activation, it did not alleviate other aforementioned changes. These results indicate that biochemical markers of cardiomyocyte cell death, such as sarcomeric disarray, gelsolin cleavage, and TUNEL-positive nuclei, are mediated, at least in part, by calpain and that calpeptin may serve as a potential therapeutic agent to prevent cardiomyocyte loss and preserve myocardial structure and function during cardiac hypertrophy. PMID:18487434

Influence of N2 partial pressure on structural and microhardness properties of TiN/ZrN multilayers deposited by Ar/N2 vacuum arc discharge

NASA Astrophysics Data System (ADS)

Naddaf, M.; Abdallah, B.; Ahmad, M.; A-Kharroub, M.

2016-08-01

The influence of N2 partial pressure on structural, mechanical and wetting properties of multilayered TiN/ZrN thin films deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures is investigated. X-ray diffraction (XRD) results show that the average texturing coefficient of (1 1 1) orientation and the grain size of both TiN and ZrN individual layers increase with increasing the N2 partial pressure. The Rutherford back scattering (RBS) measurements and analysis reveal that incorporation of the nitrogen in the film increases with increasing the N2 partial pressure and both TiN and ZrN individual layers have a nitrogen over-stoichiometry for N2 partial pressure ⩾50%. The change in the film micro-hardness is correlated to the changes in crystallographic texture, grain size, stoichiometry and the residual stress in the film as a function of the N2 partial pressure. In particular, stoichiometry of ZrN and TiN individual is found to play the vital role in determining the multilayer hardness. The multilayer film deposited at N2 partial pressure of 25% has the best stoichiometric ratio of both TiN and ZrN layers and the highest micro-hardness of about 32 GPa. In addition, water contact angle (WCA) measurements and analysis show a decrease in the work of adhesion on increasing the N2 partial pressure.

Oxygen exchange profile in rat muscles of contrasting fibre types.

PubMed

Behnke, Brad J; McDonough, Paul; Padilla, Danielle J; Musch, Timothy I; Poole, David C

2003-06-01

To determine whether fibre type affects the O2 exchange characteristics of skeletal muscle at the microcirculatory level we tested the hypothesis that, following the onset of contractions, muscle comprising predominately type I fibres (soleus, Sol, 86 % type I) would, based on demonstrated blood flow responses, exhibit a blunted microvascular PO2 (PO2,m, which is determined by the O2 delivery (QO2) to O2 uptake (VO2) ratio) profile (assessed via phosphorescence quenching) compared to muscle of primarily type II fibres (peroneal, Per, 84 % type II). PO2,m was measured at rest, and following the rest-contractions (twitch, 1 Hz, 2-4 V for 120 s) transition in Sol (n = 6) and Per (n = 6) muscles of Sprague-Dawley rats. Both muscles exhibited a delay followed by a mono-exponential decrease in PO2,m to the steady state. However, compared with Sol, Per demonstrated (1) a larger change in baseline minus steady state contracting PO2,m (DeltaPO2,m) (Per, 13.4 +/- 1.7 mmHg; Sol, 8.6 +/- 0.9 mmHg, P < 0.05); (2) a faster mean response time (i.e. time delay (TD) plus time constant (tau); Per, 23.8 +/- 1.5 s; Sol, 39.6 +/- 4.3 s, P < 0.05); and therefore (3) a greater rate of PO2,m decline (DeltaPO2,m/tau; Per, 0.92 +/- 0.08 mmHg s-1; Sol, 0.42 +/- 0.05 mmHg s-1, P < 0.05). These data demonstrate an increased microvascular pressure head of O2 at any given point after the initial time delay for Sol versus Per following the onset of contractions that is probably due to faster QO2 dynamics relative to those of VO2.

The effect of furosemide on left atrial pressure in dogs with mitral valve regurgitation.

PubMed

Suzuki, S; Ishikawa, T; Hamabe, L; Aytemiz, D; Huai-Che, H; Fukushima, R; Machida, N; Tanaka, R

2011-01-01

The effects of furosemide on left atrial pressure (LAP) in dogs with mitral regurgitation (MR) have not been documented in a quantitative manner and between different routes of administration. To document LAP and echocardiographic parameters in MR dogs administered furosemide IV or PO, in order to document changes in LAP after furosemide treatment. Five healthy Beagle dogs (3 males and 2 females; aged 2 years) were used. Experimental, cross-over, and interventional study. LAP was measured before the administration of furosemide, and 30 minutes, 1, 1.5, 2, 3, 4, 5, 6, 8, 12, and 24 hours after administration. Furosemide 1, 2, or 4 mg/kg IV, PO or placebo was administered. LAP was significantly decreased with all administrations of furosemide but not after placebo (P < .05, respectively). The max reduction was observed 1 hour (1 mg/kg IV, 15.04 ± 7.02 mmHg), 3 hours (2, 4 mg/kg IV, 13.28 ± 8.01, 9.23 ± 4.92 mmHg), 4 hours (1 mg/kg PO, 14.68 ± 11.51 mmHg), and 5 hours (2, 4 mg/kg PO, 13.19 ± 10.52, 10.70 ± 7.69 mmHg). E wave and E/Ea were significantly decreased corresponding to the reduction of LAP after administration of 2 and 4 mg/kg (P < .05, respectively). LAP was decreased in proportion to the dosage of furosemide, which did not significantly differ between IV and PO of the same dosages. E wave and E/Ea might be useful for the treatment evaluation of furosemide. Copyright © 2011 by the American College of Veterinary Internal Medicine.

Thermal, electronic and ductile properties of lead-chalcogenides under pressure.

PubMed

Gupta, Dinesh C; Bhat, Idris Hamid

2013-09-01

Fully relativistic pseudo-potential ab-initio calculations have been performed to investigate the high pressure phase transition, elastic and electronic properties of lead-chalcogenides including the less known lead polonium. The calculated ground state parameters, for the rock-salt structure show good agreement with the experimental data. PbS, PbSe, PbTe and PbPo undergo a first-order phase transition from rock-salt to CsCl structure at 19.4, 15.5, 11.5 and 7.3 GPa, respectively. The elastic properties have also been calculated. The calculations successfully predicted the location of the band gap at L-point of Brillouin zone and the band gap for each material at ambient pressure. It is observed that unlike other lead-chalcogenides, PbPo is semi-metal at ambient pressure. The pressure variation of the energy gap indicates that these materials metalize under pressure. The electronic structures of these materials have been computed in parent as well as in high pressure B2 phase.

High pressure behavior of complex phosphate K2Ce[PO4]2: Grüneisen parameter and anharmonicity properties

NASA Astrophysics Data System (ADS)

Mishra, Karuna Kara; Bevara, Samatha; Ravindran, T. R.; Patwe, S. J.; Gupta, Mayanak K.; Mittal, Ranjan; Krishnan, R. Venkata; Achary, S. N.; Tyagi, A. K.

2018-02-01

Herein we reported structural stability, vibrational and thermal properties of K2Ce[PO4]2, a relatively underexplored complex phosphate of tetravalent Ce4+ from in situ high-pressure Raman spectroscopic investigations up to 28 GPa using a diamond anvil cell. The studies identified the soft phonons that lead to a reversible phase transformation above 8 GPa, and a phase coexistence of ambient (PI) and high pressure (PII) phases in a wider pressure region 6-11 GPa. From a visual representation of the computed eigen vector displacements, the Ag soft mode at 82 cm-1 is assigned as a lattice mode of K+ cation. Pressure-induced positional disorder is apparent from the substantial broadening of internal modes and the disappearance of low frequency lattice and external modes in phase PII above 18 GPa. Isothermal mode Grüneisen parameters γi of the various phonon modes are calculated and compared for several modes. Using these values, thermal properties such as average Grüneisen parameter, and thermal expansion coefficient are estimated as 0.47, and 2.5 × 10-6 K-1, respectively. The specific heat value was estimated from all optical modes obtained from DFT calculations as 314 J-mol-1 K-1. Our earlier reported temperature dependence of phonon frequencies is used to decouple the "true anharmonic" (explicit contribution at constant volume) and "quasi harmonic" (implicit contribution brought out by volume change) contributions from the total anharmonicity. In addition to the 81 cm-1 Ag lattice mode, several other lattice and external modes of PO43- ions are found to be strongly anharmonic.

Chronic Ethanol Administration Prevents Compensatory Cardiac Hypertrophy in Pressure Overload.

PubMed

Ninh, Van K; El Hajj, Elia C; Mouton, Alan J; El Hajj, Milad C; Gilpin, Nicholas W; Gardner, Jason D

2018-05-30

Alcohol is among the most commonly abused drugs worldwide and affects many organ systems, including the heart. Alcoholic cardiomyopathy is characterized by a dilated cardiac phenotype with extensive hypertrophy and extracellular matrix (ECM) remodeling. We have previously shown that chronic ethanol (EtOH) administration accelerates the progression to heart failure in a rat model of volume overload. However, the mechanism by which this decompensation occurs is unknown. For this study, we hypothesized that chronic EtOH administration would prevent compensatory hypertrophy and cardiac remodeling in a rodent model of pressure overload (PO). Abdominal aortic constriction was used to create PO in 8-week-old male Wistar rats. Alcohol administration was performed via chronic intermittent EtOH vapor inhalation for 2 weeks prior to surgery and for the duration of the 8-week study. Echocardiography measurements were taken to assess ventricular functional and structural changes. PO increased posterior wall thickness and the hypertrophic markers, atrial and B-type natriuretic peptides (ANP and BNP). With the added stressor of EtOH, wall thickness, ANP, and BNP decreased in PO animals. The combination of PO and EtOH resulted in increased wall stress compared to PO alone. PO also caused increased expression of collagen I and III, whereas EtOH alone only increased collagen III. The combined stresses of PO and EtOH led to an increase in collagen I expression, but collagen III did not change, resulting in an increased collagen I/III ratio in the PO rats treated with EtOH. Lastly, Notch1 expression was significantly increased only in the PO rats treated with EtOH. Our data indicate that chronic EtOH may limit the cardiac hypertrophy induced by PO which may be associated with a Notch1 mechanism, resulting in increased wall stress and altered ECM profile. Copyright © 2018 by the Research Society on Alcoholism.

Mortality prediction to hospitalized patients with influenza pneumonia: PO2 /FiO2 combined lymphocyte count is the answer.

PubMed

Shi, Shu Jing; Li, Hui; Liu, Meng; Liu, Ying Mei; Zhou, Fei; Liu, Bo; Qu, Jiu Xin; Cao, Bin

2017-05-01

Community-acquired pneumonia (CAP) severity scores perform well in predicting mortality of CAP patients, but their applicability in influenza pneumonia is powerless. The aim of our research was to test the efficiency of PO 2 /FiO 2 and CAP severity scores in predicting mortality and intensive care unit (ICU) admission with influenza pneumonia patients. We reviewed all patients with positive influenza virus RNA detection in Beijing Chao-Yang Hospital during the 2009-2014 influenza seasons. Outpatients, inpatients with no pneumonia and incomplete data were excluded. We used receiver operating characteristic curves (ROCs) to verify the accuracy of severity scores or indices as mortality predictors in the study patients. Among 170 hospitalized patients with influenza pneumonia, 30 (17.6%) died. Among those who were classified as low-risk (predicted mortality 0.1%-2.1%) by pneumonia severity index (PSI) or confusion, urea, respiratory rate, blood pressure, age ≥65 year (CURB-65), the actual mortality ranged from 5.9 to 22.1%. Multivariate logistic regression indicated that hypoxia (PO 2 /FiO 2  ≤ 250) and lymphopenia (peripheral blood lymphocyte count <0.8 × 10 9 /L) were independent risk factors for mortality, with OR value of 22.483 (95% confidence interval 4.927-102.598) and 5.853 (95% confidence interval 1.887-18.152), respectively. PO 2 /FiO 2 combined lymphocyte count performed well for mortality prediction with area under the curve (AUC) of 0.945, which was significantly better than current CAP severity scores of PSI, CURB-65 and confusion, respiratory rate, blood pressure, age ≥65 years for mortality prediction (P < 0.001). The scores or indices for ICU admission prediction to hospitalized patients with influenza pneumonia confirmed a similar pattern and PO 2 /FiO 2 combined lymphocyte count was also the best predictor for predicting ICU admission. In conclusion, we found that PO 2 /FiO 2 combined lymphocyte count is simple and reliable predictor of hospitalized patients with influenza pneumonia in predicting mortality and ICU admission. When PO 2 /FiO 2  ≤ 250 or peripheral blood lymphocyte count <0.8 × 10 9 /L, the clinician should pay great attention to the possibility of severe influenza pneumonia. © 2015 The Authors. The Clinical Respiratory Journal published by John Wiley & Sons Ltd.

Premelting, Melting, and Degradation Properties of Molten Alkali Nitrates: LiNO3, NaNO3, KNO3, and Binary NaNO3-KNO3

NASA Astrophysics Data System (ADS)

Mohammad, Mehedi Bin; Brooks, Geoffrey Alan; Rhamdhani, Muhammad Akbar

2018-02-01

A simultaneous thermal analyzer (STA) was used to observe the transition and degradation events of LiNO3, NaNO3, KNO3, and binary NaNO3-KNO3 salts for potential use as phase change materials (PCMs) and heat transfer fluid (HTF). Samples were heated from 50 °C to 800 °C at 10 °C/min scanning rate in three atmospheres (argon, air, and oxygen) using an STA to observe decomposition behavior. Thermal stability increased for all salts at high partial pressure of O2 ( P_{{{O}2 }} = 1.0) compared to inert argon ( P_{{{O}2 }} = 0). O2, N2, NO, N2O, and NO2 were main evolved gases during nitrate decomposition. NO and O2 started to evolve at approximately the same temperature after melting, indicating that primary and secondary decomposition reactions were concurrent and overlapping. The solid-solid transition, liquidus and solidus temperatures, heat of transition, heat of melting, and heat of solidification were obtained at various heating-cooling rates (1, 2, 4, 5, 6, 8, 10, and 15 °C/min) using an STA. At all heating-cooling rates, a small gap exists between liquidus and solidus temperatures for all samples due to the salts exhibiting supercooling phenomena. This study showed that the degradation point depends on the blanket atmosphere top of the molten salts and that heating rates have a minor effect on transition events (peaks height, peaks width, and transition enthalpies).

Premelting, Melting, and Degradation Properties of Molten Alkali Nitrates: LiNO3, NaNO3, KNO3, and Binary NaNO3-KNO3

NASA Astrophysics Data System (ADS)

Mohammad, Mehedi Bin; Brooks, Geoffrey Alan; Rhamdhani, Muhammad Akbar

2018-06-01

A simultaneous thermal analyzer (STA) was used to observe the transition and degradation events of LiNO3, NaNO3, KNO3, and binary NaNO3-KNO3 salts for potential use as phase change materials (PCMs) and heat transfer fluid (HTF). Samples were heated from 50 °C to 800 °C at 10 °C/min scanning rate in three atmospheres (argon, air, and oxygen) using an STA to observe decomposition behavior. Thermal stability increased for all salts at high partial pressure of O2 ( P_{{{O}2 }} = 1.0) compared to inert argon ( P_{{{O}2 }} = 0). O2, N2, NO, N2O, and NO2 were main evolved gases during nitrate decomposition. NO and O2 started to evolve at approximately the same temperature after melting, indicating that primary and secondary decomposition reactions were concurrent and overlapping. The solid-solid transition, liquidus and solidus temperatures, heat of transition, heat of melting, and heat of solidification were obtained at various heating-cooling rates (1, 2, 4, 5, 6, 8, 10, and 15 °C/min) using an STA. At all heating-cooling rates, a small gap exists between liquidus and solidus temperatures for all samples due to the salts exhibiting supercooling phenomena. This study showed that the degradation point depends on the blanket atmosphere top of the molten salts and that heating rates have a minor effect on transition events (peaks height, peaks width, and transition enthalpies).

Effects of transcutaneous topical injection of oxygen on vascular endothelial growth factor gene into the healing ligament in rats.

PubMed

Ishii, Yoshimasa; Ushida, Takashi; Tateishi, Tetsuya; Miyanaga, Yutaka

2003-11-01

The effects of intermittent exposure to oxygen injection on an experimentally induced ligament tear were studied in the right hind limb of 17 male Sprague-Dawley rats. Two rats were used for monitoring the partial oxygen pressure (pO(2)) of subcutaneous tissue and 15 rats were divided into the following three groups of 5 after an experimentally induced ligament tear: Group A, control group; Group B, injection of 0.5 ml hyaluronan to the wound transcutaneously; Group C, injection of 0.5 ml hyaluronan mixed with haemoglobin and oxygen (n=5). At 7 days post-ligament injury, we compared the ligaments of the three treatment groups for gross appearance, histology and expression of vascular endothelial growth factor (VEGF) mRNA by RT-PCR. Our results indicate that the pO(2) was immediately elevated to 334.6 mmHg by topical oxygen injection and this method was effective in promoting vessel formation in comparison to the control group (p<0.01). However, the expression of VEGF mRNA in the topical oxygen injection group (Group C) was lower than that in control group (p<0.05). Our results suggest that oxygen is able to accelerate vessel formation in spite of its effect of decreasing VEGF mRNA. Our method of using topical injection proved to be useful in healing the ligament and the wound.

Effect of oxygen supply on the size of implantable islet-containing encapsulation devices.

PubMed

Papas, Klearchos K; Avgoustiniatos, Efstathios S; Suszynski, Thomas M

2016-03-01

Beta-cell replacement therapy is a promising approach for the treatment of diabetes but is currently limited by the human islet availability and by the need for systemic immunosuppression. Tissue engineering approaches that will enable the utilization of islets or β-cells from alternative sources (such as porcine islets or human stem cell derived beta cells) and minimize or eliminate the need for immunosuppression have the potential to address these critical limitations. However, tissue engineering approaches are critically hindered by the device size (similar to the size of a large flat screen television) required for efficacy in humans. The primary factor dictating the device size is the oxygen availability to islets to support their viability and function (glucose-stimulated insulin secretion [GSIS]). GSIS is affected (inhibited) at a much higher oxygen partial pressure [pO2] than that of viability (e.g. 10 mmHg as opposed to 0.1 mmHg). Enhanced oxygen supply (higher pO2) than what is available in vivo at transplant sites can have a profound effect on the required device size (potentially reduce it to the size of a postage stamp). This paper summarizes key information on the effect of oxygen on islet viability and function within immunoisolation devices and describes the potential impact of enhanced oxygen supply to devices in vivo on device size reduction.

STAT3 activation in pressure-overloaded feline myocardium: role for integrins and the tyrosine kinase BMX.

PubMed

Willey, Christopher D; Palanisamy, Arun P; Johnston, Rebecca K; Mani, Santhosh K; Shiraishi, Hirokazu; Tuxworth, William J; Zile, Michael R; Balasubramanian, Sundaravadivel; Kuppuswamy, Dhandapani

2008-06-27

Growth, survival and cytoskeletal rearrangement of cardiomyocytes are critical for cardiac hypertrophy. Signal transducer and activator of transcription-3 (STAT3) activation is an important cardioprotective factor associated with cardiac hypertrophy. Although STAT3 activation has been reported via signaling through Janus Kinase 2 (JAK2) in several cardiac models of hypertrophy, the importance of other nonreceptor tyrosine kinases (NTKs) has not been explored. Utilizing an in vivo feline right ventricular pressure-overload (RVPO) model of hypertrophy, we demonstrate that in 48 h pressure-overload (PO) myocardium, STAT3 becomes phosphorylated and redistributed to detergent-insoluble fractions with no accompanying JAK2 activation. PO also caused increased levels of phosphorylated STAT3 in both cytoplasmic and nuclear fractions. To investigate the role of other NTKs, we used our established in vitro cell culture model of hypertrophy where adult feline cardiomyocytes are embedded three-dimensionally (3D) in type-I collagen and stimulated with an integrin binding peptide containing an Arg-Gly-Asp (RGD) motif that we have previously shown to recapitulate the focal adhesion complex (FAC) formation of 48 h RVPO. RGD stimulation of adult cardiomyocytes in vitro caused both STAT3 redistribution and activation that were accompanied by the activation and redistribution of c-Src and the TEC family kinase, BMX, but not JAK2. However, infection with dominant negative c-Src adenovirus was unable to block RGD-stimulated changes on either STAT3 or BMX. Further analysis in vivo in 48 h PO myocardium showed the presence of both STAT3 and BMX in the detergent-insoluble fraction with their complex formation and phosphorylation. Therefore, these studies indicate a novel mechanism of BMX-mediated STAT3 activation within a PO model of cardiac hypertrophy that might contribute to cardiomyocyte growth and survival.

Erratum to: Blood HbO2 and HbCO2 dissociation curves at varied O2, CO2, pH, 2,3-DPG and temperature levels.

PubMed

Dash, Ranjan K; Bassingthwaighte, James B

2010-04-01

New mathematical model equations for O(2) and CO(2) saturations of hemoglobin (S(HbO)(2) and S(HbCO)(2) are developed here from the equilibrium binding of O(2) and CO(2) with hemoglobin inside RBCs. They are in the form of an invertible Hill-type equation with the apparent Hill coefficients KHbO(2) and KHbCO(2) in the expressions for SHbO(2) and SHbCO(2) dependent on the levels of O(2) and CO(2) partial pressures (P(O)(2) and P(CO)(2)), pH, 2,3-DPG concentration, and temperature in blood. The invertibility of these new equations allows PO(2) and PCO(2) to be computed efficiently from S(HbO)(2) and S(HbCO)(2) and vice versa. The oxyhemoglobin (HbO(2)) and carbamino-hemoglobin (HbCO(2)) dissociation curves computed from these equations are in good agreement with the published experimental and theoretical curves in the literature. The model solutions describe that, at standard physiological conditions, the hemoglobin is about 97.2% saturated by O(2) and the amino group of hemoglobin is about 13.1% saturated by CO(2). The O(2) and CO(2) content in whole blood are also calculated here from the gas solubilities, hematocrits, and the new formulas for S(HbO)(2) and S(HbCO)(2). Because of the mathematical simplicity and invertibility, these new formulas can be conveniently used in the modeling of simultaneous transport and exchange of O(2) and CO(2) in the alveoli-blood and blood-tissue exchange systems.

O(2)-dependent K(+) fluxes in trout red blood cells: the nature of O(2) sensing revealed by the O(2) affinity, cooperativity and pH dependence of transport.

PubMed

Berenbrink, M; Völkel, S; Heisler, N; Nikinmaa, M

2000-07-01

The effects of pH and O(2) tension on the isotonic ouabain-resistant K(+) (Rb+) flux pathway and on haemoglobin O2 binding were studied in trout red blood cells (RBCs) in order to test for a direct effect of haemoglobin O(2) saturation on K(+) transport across the RBC membrane. At pH values corresponding to in vivo control arterial plasma pH and higher, elevation of the O(2) partial pressure (PO(2)) from 7.8 to 157 mmHg increased unidirectional K(+) influx across the RBC membrane several-fold. At lower extracellular pH values, stimulation of K(+) influx by O(2) was depressed, exhibiting an apparent pK(a) (pK'(a)) for the process of 8.0. Under similar conditions the pK'(a) for acid-induced deoxygenation of haemoglobin (Hb) was 7.3. When trout RBCs were exposed to PO(2) values between 0 and 747 mmHg, O(2) equilibrium curves typical of Hb O(2) saturation were also obtained for K(+) influx and efflux. However, at pH 7.9, the PO(2) for half-maximal K(+) efflux and K(+) influx (P50) was about 8- to 12-fold higher than the P(50) for Hb-O(2) binding. While K(+) influx and efflux stimulation by O(2) was essentially non-cooperative, Hb-O(2) equilibrium curves were distinctly sigmoidal (Hill parameters close to 1 and 3, respectively). O(2)-stimulated K(+) influx and efflux were strongly pH dependent. When the definition of the Bohr factor for respiratory pigments (Phi = delta logP50 x delta pH(-1)) was extended to the effect of pH on O(2)-dependent K(+) influx and efflux, extracellular Bohr factors (Phi(o) of -2.00 and -2.06 were obtained, values much higher than that for Hb (Phi(o) = -0.49). The results of this study are consistent with an O(2) sensing mechanism differing markedly in affinity and cooperativity of O(2) binding, as well as in pH sensitivity, from bulk Hb.

High-pressure structural, elastic, and thermodynamic properties of zircon-type HoPO 4 and TmPO 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomis, O.; Lavina, B.; Rodríguez-Hernández, P.

2017-01-20

Zircon-type holmium phosphate (HoPO 4) and thulium phosphate (TmPO 4) have been studied by single-crystal x-ray diffraction and ab initio calculations. We report on the influence of pressure on the crystal structure, and on the elastic and thermodynamic properties. The equation of state for both compounds is accurately determined. We have also obtained information on the polyhedral compressibility which is used to explain the anisotropic axial compressibility and the bulk compressibility. Both compounds are ductile and more resistive to volume compression than to shear deformation at all pressures. Furthermore, the elastic anisotropy is enhanced upon compression. Finally, the calculations indicatemore » that the possible causes that make the zircon structure unstable are mechanical instabilities and the softening of a silent B 1u mode.« less

Earth's partial pressure of CO2 over the past 120 Ma; evidence from Ce anomalies in the deep (greater than 600 m) Pacific Ocean, 1

NASA Technical Reports Server (NTRS)

Liu, Y.-G; Schmitt, R. A.

1993-01-01

It was found that Ce serves as a chemical tracer of paleo-oceanic redox conditions. It was shown that the unoxidized and soluble Ce(3+) in modern seawater exhibits a negative anomaly relative to the other soluble REE(3+). An expression of soluble Ce(3+) in seawater that was approximately 1900X greater than the average observed in Ce in 600-5000 m Pacific seawater was derived. Since Ce(CO3)(+) and Ce(CO3)2(-) complexes greatly exceed the Ce(PO4) complexes in seawater, the formulations of using carbonate complexes were followed and it was found that the calculated Ce and observed concentrations in the deep 600-5000 m Pacific Ocean agree within the uncertainties of the thermodynamic data. As expected, the calculated Ce concentrations are a strong function of pH and found to be lesser functions of CO3(2-) activities.

Effects of acupuncture on tissue oxygenation of the rat brain.

PubMed

Chen, G S; Erdmann, W

1978-04-01

Acupuncture has been claimed to be effective in restoring consciousness in some comatose patients. Possible mechanisms to explain alleged acupuncture-induced arousal may include vasodilatory effects caused by smypathetic stimulation which leads to an augmentation of cerebral microcirculation and thereby improves oxygen supply to the brain tissue. Experiments were performed in ten albino rats (Wistar) employing PO2 microelectrodes which were inserted into the cortex through small burholes. Brain tissue PO2 was continuously recorded before, during, and after acupuncture. Stimulation of certain acupuncture points (Go-26) resulted in immediate increase of PO2 in the frontal cortex of the rat brain. This effect was reproducible and was comparable to that obtained with increase of inspiratory CO2 known to induce arterial vasodilatation and thus capillary perfusion pressure. The effect was more significant as compared to tissue PO2 increases obtained after increase in inspiratory oxygen concentration from 21% to 100%. It appears that acupuncture causes increased brain tissue perfusion which may be, at least in part, responsible for arousal of unconscious patients.

[Influence of hypoxia and hyperoxia on the 2,3-diphosphoglycerate concentration in rat red blood cells].

PubMed

Gross, J; Beischukurowa, A; Lun, A; Pohle, R; Voitkevich, V; Scherba, M M

1978-01-01

The influence of hypoxia (pO2 = 85 mmHg) lasting 5 h, a strong single bleeding of the animals, and the effect of hyperoxia (pO2 = 745 and 1520 mmHg) lasting 24 and 5 h, respectively, on the 2.3-DPG concentration of red cells from rat has been studied. A distinct increase in 2.3-DPG concentration at hypoxia and bleedig, but no reliable alteration in hyperoxia were found. When bled and anemic animals are exposed to hyperoxia (24 h, pO2 = 745 mmHg, normal air pressure) there is also observed a rise of 2.3-DPG concentration, which is much less than in normoxia. A non-linear relationship was established between the change of 2.3-DPG concentration and the percentage of deoxyhemoglobin in the centralvenous blood.

Containerless Processing: Fabrication of Advanced Functional Materials from Undercooled Oxide Melt

NASA Astrophysics Data System (ADS)

Kumar, M. S. Vijaya; Ishikawa, Takehiko; Yoda, Shinichi; Kuribayashi, Kazuhiko

2012-07-01

Materials science in Microgravity condition is one of newly established cutting edge science field. After the effort of space development and space utilization, microgravity of space environment has been considered as one of novel tools for materials science because it assures containerless levitation. Containerless processing is a promising technique to explore the technologically important materials using rapid solidification of an undercooled melt. Recently, rare-earth ferrites and manganites have attracted great interest towards their wide applications in the field of electronic industry. Among these new hexagonal phases with a space group of P6 _{3}cm are technologically important materials because of multiferroic characteristics, i.e., the coexistence of ferroelectricity and magnetism in one compound. In the present study, containerless solidification of the R-Fe-O, and R-Mn-O melts were carried out to fabricate multiferroics under the controlled Po _{2}. Containerless processing is a promising technique to explore the new materials using rapid solidification of an undercooled melt because it provides large undercooling prior to nucleation. In order to undercool the melt deeply below the melting temperature under a precisely controlled oxygen partial pressure, an aerodynamic levitator (ADL) combined with ZrO _{2} oxygen sensor was designed. A spherical RFeO _{3} and RMnO _{3} sample was levitated by an ADL and completely melted by a CO _{2} laser in an atmosphere with predetermined Po _{2}.The surface temperature of the levitated droplet was monitored by a two-color pyrometer. Then, the droplet was cooled by turning off the CO _{2} laser. The XRD results of the rapidly solidified LuFeO _{3} and LuMnO _{3} samples at Po _{2} of 1x10 ^{5} Pa confirms the existence of the hexagonal metastable LuFeO _{3} phase. On the other hand, orthorhombic RFeO _{3} (R=Yb, Er, Y and Dy)and hexagonal RMnO _{3} (R=Ho-Lu)phases were identified. The cross-sectioned scanning electron microscopy (SEM) images and TG/DTA results revealed the existence of the stable and metastable phases with decreasing Po _{2}. The magnetic properties of the as-solidified samples were studied using vibrating sample magnetometer (VSM). These results indicate that a metastable and stable phase solidifies directly from the undercooled melt even when the melt is undercooled much below the peritectic temperature.

Skin blood flow: a comparison of transcutaneous oximetry and laser Doppler flowmetry.

PubMed

Allen, P I; Goldman, M

1987-10-01

In normal limbs skin blood flow (SBF) falls on standing, but in ischaemic limbs there is a characteristic blush on dependancy. We studied the effect of changing posture in a range of ischaemic limbs, using two non-invasive techniques--laser Doppler (LD) and transcutaneous oximetry (TcPO2). Warmed TcPO2 and LD probes were placed over the first metatarsal cleft and SBF recorded with the limb horizontal, dependant and elevated. Ankle to brachial pressure ratios (A:B) were also measured. Twelve patients with lower limb ischaemia, mean A:B ratio 0.5 +/- 0.21 (+/- S.D.) were compared with 21 asymptomatic controls, mean A:B ratio 1.2 +/- 0.15. In the controls, neither TcPO2 nor LD values changed significantly with limb position. Both flux and oxygen tension were significantly lower in ischaemic limbs in all positions; on lowering the ischaemic limb, flux unexpectedly rose to 23.5 +/- 17.7 V from a mean of 14 + 9.0 V (horizontal). Both TcPO2 and LD correlated well with A:B ratio in two positions: horizontal r (TcPO2) = 0.73, r(LD) = 0.57; elevated r(TcPO2) = 0.78, r(LD) = 0.68. Overall there was a highly significant correlation between LD and TcPO2 (r = 0.6, P less than 0.001, Student's test), but this was strongest in the elevated position (r = 0.87, P less than 0.001). LD and TcPO2 relate to A:B ratio and to each other, particularly in the stressed limb; in the well perfused limb, the poorer correlation suggests skin perfusion is not linearly related to tissue oxygen tension.

Accuracy of pulse oximetry measurement of heart rate of newborn infants in the delivery room.

PubMed

Kamlin, C Omar F; Dawson, Jennifer A; O'Donnell, Colm P F; Morley, Colin J; Donath, Susan M; Sekhon, Jasbir; Davis, Peter G

2008-06-01

To determine the accuracy of heart rate obtained by pulse oximetry (HR(PO)) relative to HR obtained by 3-lead electrocardiography (HR(ECG)) in newborn infants in the delivery room. Immediately after birth, a preductal PO sensor and ECG leads were applied. PO and ECG monitor displays were recorded by a video camera. Two investigators reviewed the videos. Every two seconds, 1 of the investigators recorded HR(PO) and indicators of signal quality from the oximeter while masked to ECG, whereas the other recorded HR(ECG) and ECG signal quality while masked to PO. HR(PO) and HR(ECG) measurements were compared using Bland-Altman analysis. We attended 92 deliveries; 37 infants were excluded due to equipment malfunction. The 55 infants studied had a mean (+/-standard deviation [SD]) gestational age of 35 (+/-3.7) weeks, and birth weight 2399 (+/-869) g. In total, we analyzed 5877 data pairs. The mean difference (+/-2 SD) between HR(ECG) and HR(PO) was -2 (+/-26) beats per minute (bpm) overall and -0.5 (+/-16) bpm in those infants who received positive-pressure ventilation and/or cardiac massage. The sensitivity and specificity of PO for detecting HR(ECG) <100 bpm was 89% and 99%, respectively. PO provided an accurate display of newborn infants' HR in the delivery room, including those infants receiving advanced resuscitation.

High-affinity hemoglobin and blood oxygen saturation in diving emperor penguins.

PubMed

Meir, Jessica U; Ponganis, Paul J

2009-10-01

The emperor penguin (Aptenodytes forsteri) thrives in the Antarctic underwater environment, diving to depths greater than 500 m and for durations longer than 23 min. To examine mechanisms underlying the exceptional diving ability of this species and further describe blood oxygen (O2) transport and depletion while diving, we characterized the O2-hemoglobin (Hb) dissociation curve of the emperor penguin in whole blood. This allowed us to (1) investigate the biochemical adaptation of Hb in this species, and (2) address blood O2 depletion during diving, by applying the dissociation curve to previously collected partial pressure of O2 (PO2) profiles to estimate in vivo Hb saturation (SO2) changes during dives. This investigation revealed enhanced Hb-O2 affinity (P50=28 mmHg, pH 7.5) in the emperor penguin, similar to high-altitude birds and other penguin species. This allows for increased O2 at low blood PO2 levels during diving and more complete depletion of the respiratory O2 store. SO2 profiles during diving demonstrated that arterial SO2 levels are maintained near 100% throughout much of the dive, not decreasing significantly until the final ascent phase. End-of-dive venous SO2 values were widely distributed and optimization of the venous blood O2 store resulted from arterialization and near complete depletion of venous blood O2 during longer dives. The estimated contribution of the blood O2 store to diving metabolic rate was low and highly variable. This pattern is due, in part, to the influx of O2 from the lungs into the blood during diving, and variable rates of tissue O2 uptake.

Structural, mechanical, electrical and wetting properties of ZrNx films deposited by Ar/N2 vacuum arc discharge: Effect of nitrogen partial pressure

NASA Astrophysics Data System (ADS)

Abdallah, B.; Naddaf, M.; A-Kharroub, M.

2013-03-01

Non-stiochiometric zirconium nitride (ZrNx) thin films have been deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures at different N2 partial pressure ratio. The microstructure, mechanical, electrical and wetting properties of these films are studied by means of X-ray diffraction (XRD), micro-Raman spectroscopy, Rutherford back scattering (RBS) technique, conventional micro-hardness testing, electrical resistivity, atomic force microscopy (AFM) and contact angle (CA) measurements. RBS results and analysis show that the (N/Zr) ratio in the film increases with increasing the N2 partial pressure. A ZrNx film with (Zr/N) ratio in the vicinity of stoichiometric ZrN is obtained at N2 partial pressure of 10%. XRD and Raman results indicate that all deposited films have strained cubic crystal phase of ZrN, regardless of the N2 partial pressure. On increasing the N2 partial pressure, the relative intensity of (1 1 1) orientation with respect to (2 0 0) orientation is seen to decrease. The effect of N2 partial pressure on micro-hardness and the resistivity of the deposited film is revealed and correlated to the alteration of grain size, crystallographic texture, stoichiometry and residual stress developed in the film. In particular, it is found that residual stress and nitrogen incorporation in the film play crucial role in the alteration of micro-hardness and resistivity respectively. In addition, CA and AFM results demonstrate that as N2 partial pressure increases, both the surface hydrophobicity and roughness of the deposited film increase, leading to a significant decrease in the film surface free energy (SFE).

Crystal structures of lazulite-type oxidephosphates Ti IIITi IV3O 3(PO 4) 3 and MIII4Ti IV27O 24(PO 4) 24 ( MIII=Ti, Cr, Fe)

NASA Astrophysics Data System (ADS)

Schöneborn, M.; Glaum, R.; Reinauer, F.

2008-06-01

Single crystals of the oxidephosphates Ti IIITi IV3O 3(PO 4) 3 (black), Cr III4Ti IV27O 24(PO 4) 24 (red-brown, transparent), and Fe III4Ti IV27O 24(PO 4) 24 (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2 dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [Ti IIITi IV3O 3(PO 4) 3: Z=24, a=7.3261(9) Å, b=22.166(5) Å, c=39.239(8) Å, R1=0.029, w R2=0.084, 6055 independent reflections, 301 variables; Cr III4Ti IV27O 24(PO 4) 24: Z=1, a=7.419(3) Å, b=21.640(5) Å, c=13.057(4) Å, R1=0.037, w R2=0.097, 1524 independent reflections, 111 variables; Fe III4Ti IV27O 24(PO 4) 24: Z=1, a=7.4001(9) Å, b=21.7503(2) Å, c=12.775(3) Å, R1=0.049, w R2=0.140, 1240 independent reflections, 112 variables). For Ti IIITi IVO 3(PO 4) 3 a well-ordered structure built from dimers [Ti III,IV2O 9] and [Ti IV,IV2O 9] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr 4Ti 27O 24(PO 4) 24 and Fe 4Ti 27O 24(PO 4) 24, consisting of dimers [ MIIITi IVO 9] and [Ti IV,IV2O 9], monomeric [Ti IVO 6] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs Ti III4Ti IV27O 24(PO 4) 24 ( a=7.418(2) Å, b=21.933(6) Å, c=12.948(7) Å) is isotypic to the oxidephosphates MIII4Ti IV27O 24(PO 4) 24 ( MIII: Cr, Fe). The UV/vis spectrum of Cr 4Ti 27O 24(PO 4) 24 reveals a rather small ligand-field splitting Δ o=14,370 cm -1 and a very low nephelauxetic ratio β=0.72 for the chromophores [Cr IIIO 6] within the dimers [Cr IIITi IVO 9].

Growth of healthy term infants fed partially hydrolyzed whey-based infant formula: a randomized, blinded, controlled trial.

PubMed

Borschel, Marlene W; Choe, Yong S; Kajzer, Janice A

2014-12-01

Partially hydrolyzed formulas (pHF) represent a significant percentage of the infant formula market. A new whey-based, palm olein oil (PO)-free pHF was developed and a masked, randomized, parallel growth study was conducted in infants fed this formula or a commercially available whey-based pHF with PO. Infants between 0 and 8 days were to be enrolled and studied to 119 days of age. Growth and tolerance of infants were evaluated. Mean weight gain from 14 to 119 days of age was similar between groups. There were no significant differences between groups in weight, length, head circumference (HC), or length or HC gains. Infants fed the new PO-free pHF had significantly softer stools than those fed the PO-containing formula except at 119 days of age. This study demonstrates that whereas growth of infants fed different formulas during the first 4 months of life may be similar, infants may tolerate individual formulas differently. © The Author(s) 2014.

Intratumoral oxygen gradients mediate sarcoma cell invasion

PubMed Central

Lewis, Daniel M.; Park, Kyung Min; Tang, Vitor; Xu, Yu; Pak, Koreana; Eisinger-Mathason, T. S. Karin; Simon, M. Celeste; Gerecht, Sharon

2016-01-01

Hypoxia is a critical factor in the progression and metastasis of many cancers, including soft tissue sarcomas. Frequently, oxygen (O2) gradients develop in tumors as they grow beyond their vascular supply, leading to heterogeneous areas of O2 depletion. Here, we report the impact of hypoxic O2 gradients on sarcoma cell invasion and migration. O2 gradient measurements showed that large sarcoma mouse tumors (>300 mm3) contain a severely hypoxic core [≤0.1% partial pressure of O2 (pO2)] whereas smaller tumors possessed hypoxic gradients throughout the tumor mass (0.1–6% pO2). To analyze tumor invasion, we used O2-controllable hydrogels to recreate the physiopathological O2 levels in vitro. Small tumor grafts encapsulated in the hydrogels revealed increased invasion that was both faster and extended over a longer distance in the hypoxic hydrogels compared with nonhypoxic hydrogels. To model the effect of the O2 gradient accurately, we examined individual sarcoma cells embedded in the O2-controllable hydrogel. We observed that hypoxic gradients guide sarcoma cell motility and matrix remodeling through hypoxia-inducible factor-1α (HIF-1α) activation. We further found that in the hypoxic gradient, individual cells migrate more quickly, across longer distances, and in the direction of increasing O2 tension. Treatment with minoxidil, an inhibitor of hypoxia-induced sarcoma metastasis, abrogated cell migration and matrix remodeling in the hypoxic gradient. Overall, we show that O2 acts as a 3D physicotactic agent during sarcoma tumor invasion and propose the O2-controllable hydrogels as a predictive system to study early stages of the metastatic process and therapeutic targets. PMID:27486245

Intratumoral oxygen gradients mediate sarcoma cell invasion.

PubMed

Lewis, Daniel M; Park, Kyung Min; Tang, Vitor; Xu, Yu; Pak, Koreana; Eisinger-Mathason, T S Karin; Simon, M Celeste; Gerecht, Sharon

2016-08-16

Hypoxia is a critical factor in the progression and metastasis of many cancers, including soft tissue sarcomas. Frequently, oxygen (O2) gradients develop in tumors as they grow beyond their vascular supply, leading to heterogeneous areas of O2 depletion. Here, we report the impact of hypoxic O2 gradients on sarcoma cell invasion and migration. O2 gradient measurements showed that large sarcoma mouse tumors (>300 mm(3)) contain a severely hypoxic core [≤0.1% partial pressure of O2 (pO2)] whereas smaller tumors possessed hypoxic gradients throughout the tumor mass (0.1-6% pO2). To analyze tumor invasion, we used O2-controllable hydrogels to recreate the physiopathological O2 levels in vitro. Small tumor grafts encapsulated in the hydrogels revealed increased invasion that was both faster and extended over a longer distance in the hypoxic hydrogels compared with nonhypoxic hydrogels. To model the effect of the O2 gradient accurately, we examined individual sarcoma cells embedded in the O2-controllable hydrogel. We observed that hypoxic gradients guide sarcoma cell motility and matrix remodeling through hypoxia-inducible factor-1α (HIF-1α) activation. We further found that in the hypoxic gradient, individual cells migrate more quickly, across longer distances, and in the direction of increasing O2 tension. Treatment with minoxidil, an inhibitor of hypoxia-induced sarcoma metastasis, abrogated cell migration and matrix remodeling in the hypoxic gradient. Overall, we show that O2 acts as a 3D physicotactic agent during sarcoma tumor invasion and propose the O2-controllable hydrogels as a predictive system to study early stages of the metastatic process and therapeutic targets.

Effect of Partial Pressure of Oxygen and Activity of Carbon on the Corrosion of High Temperature Alloys in s-CO2 Environments

NASA Astrophysics Data System (ADS)

Mahaffey, Jacob Thomas

Over the course of the past couple decades, increased concern has grown on the topics of climate change and energy consumption, focusing primarily on carbon emissions. With modernization of countries like India and China, there are no signs of slowing of global carbon emissions and energy usage. To combat this, new more efficient power conversion cycles must be utilized. The Supercritical Carbon Dioxide (s-CO2) Brayton cycle promises increased efficiency and smaller component sizes. These cycles will push the limits of current high temperature materials, and must be studied before implementation is made possible. A large collection of high temperature CO2 corrosion research has been reported over the last thirty years. While many of the studies in the past have focused on corrosion in research grade (RG) (99.999%) and industrial grade (IG) (99.5%) CO2, very few have focused on studying the specific effects that impurities can have on the corrosion rates and mechanisms. The work described in this document will lay the foundation for advancement of s-CO2 corrosion studies. A testing facility has been constructed and was designed as an open flow s-CO2 loop with a fluid residence time of 2 hours. This facility is capable of heating up to 750°C at pressures up to 20 MPa. Instrumentation for monitoring oxygen and carbon monoxide concentration were added to make measurements both before and after sample exposure, for the duration of testing. Testing of both model and commercial alloys was conducted for temperatures ranging from 450-750°C at 20MPa for 1,000 hours. The effect of the partial pressure of oxygen (pO2) was studied by adding 100ppm of O2 to RG CO2 during testing. The activity of carbon (aC) was studied by adding 1%CO to RG CO2. Each environment greatly altered the mechanisms and rates of oxidation and carburization on each material exposed to the environment.

The influence of the position of the oxygen dissociation curve on oxygen-dependent functions of the isolated perfused rat liver. I. Studies at different levels of hypoxic hypoxia.

PubMed

Bakker, J C; Gortmaker, G C; Vrolijk, A C; Offerijns, F G

1976-03-11

Isolated rat livers were perfused with fresh and 2,3-DPG (2,3-diphosphoglycerate)-depleted human erythrocytes at different levels of hypoxia. The mean P50 values of the measured actual oxygen dissociation curves (O.D.C.) were 24.5 and 18 mm Hg. No changes in flow rate and perfusion pressure occurred under the different experimental conditons. It was shown that an advantage or disadvantage of a shift of the O.D.C. depends on the degree of hypoxia, as reflected in the venous PO2. Perfusions with fresh erythrocytes showed higher venous PO2 values during normoxia or moderate hypoxia and lower venous PO2 values at severe hypoxia. A cross-over point was found at a PO2 in the portal vein of 36 mm Hg. The disadvantage of perfusions with fresh erythrocytes at severre hypoxia was also reflected in higher cytoplasmatic and mitochondrial redox levels. Using bile flow rate as an indirect measure for the rate of hydroxylation-dependent O2 consumption a favourable effect of perfusion with fresh erythrocytes was found at a PO2 in the portal vein of 100 and 40 mm Hg.

The impact of person-organization fit on innovative work behavior: the mediating effect of knowledge sharing behavior.

PubMed

Afsar, Bilal

2016-01-01

The direct relationship between person-organization (P-O) fit and employee's positive work attitudes and behaviours have been well researched. However, there has been no study on the impact of P-O fit on innovative work behaviour (IWB) of the nurses. The purpose of this paper is to fill this gap in the literature. In order to give a complete understanding of the psychology surrounding P-O fit, this study has longitudinally analysed the relationship between P-O fit and IWB along with the impact of a potential mediator, i.e. knowledge sharing behaviour (KSB) on this relationship. A total of 357 nurses and 71 doctors from three government hospitals of Thailand filled out the questionnaires. Structural equation modelling was used to analyse the relationships. Results of the study indicate that a nurse's P-O fit is positively associated with both self and doctor ratings of innovative behaviours; and KSB acts as a partial mediator between P-O fit and IWB at both Times 1 and 2. These results imply that a nurse's perceived fit in the hospital impacts his/her engagement into IWB. As nurses share knowledge with their co-workers frequently, it tends to strengthen the relationship between P-O fit and IWB. Study findings begin to explain how P-O fit impacts IWB of nurses. Specifically, the author find that KSB explains the relationship between P-O fit and IWB.

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model.

PubMed

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

Lipocalin-2 induces NLRP3 inflammasome activation via HMGB1 induced TLR4 signaling in heart tissue of mice under pressure overload challenge

PubMed Central

Song, Erfei; Jahng, James WS; Chong, Lisa P; Sung, Hye K; Han, Meng; Luo, Cuiting; Wu, Donghai; Boo, Stellar; Hinz, Boris; Cooper, Matthew A; Robertson, Avril AB; Berger, Thorsten; Mak, Tak W; George, Isaac; Schulze, P Christian; Wang, Yu; Xu, Aimin; Sweeney, Gary

2017-01-01

Lipocalin-2 (also known as NGAL) levels are elevated in obesity and diabetes yet relatively little is known regarding effects on the heart. We induced pressure overload (PO) in mice and found that lipocalin-2 knockout (LKO) mice exhibited less PO-induced autophagy and NLRP3 inflammasome activation than Wt. PO-induced mitochondrial damage was reduced and autophagic flux greater in LKO mice, which correlated with less cardiac dysfunction. All of these observations were negated upon adenoviral-mediated restoration of normal lipocalin-2 levels in LKO. Studies in primary cardiac fibroblasts indicated that lipocalin-2 enhanced priming and activation of NLRP3-inflammasome, detected by increased IL-1β, IL-18 and Caspase-1 activation. This was attenuated in cells isolated from NLRP3-deficient mice or upon pharmacological inhibition of NLRP3. Furthermore, lipocalin-2 induced release of HMGB1 from cells and NLRP3-inflammasome activation was attenuated by TLR4 inhibition. We also found evidence of increased inflammasome activation and reduced autophagy in cardiac biopsy samples from heart failure patients. Overall, this study provides new mechanistic insight on the detrimental role of lipocalin-2 in the development of cardiac dysfunction. PMID:28670364

Lipocalin-2 induces NLRP3 inflammasome activation via HMGB1 induced TLR4 signaling in heart tissue of mice under pressure overload challenge.

PubMed

Song, Erfei; Jahng, James Ws; Chong, Lisa P; Sung, Hye K; Han, Meng; Luo, Cuiting; Wu, Donghai; Boo, Stellar; Hinz, Boris; Cooper, Matthew A; Robertson, Avril Ab; Berger, Thorsten; Mak, Tak W; George, Isaac; Schulze, P Christian; Wang, Yu; Xu, Aimin; Sweeney, Gary

2017-01-01

Lipocalin-2 (also known as NGAL) levels are elevated in obesity and diabetes yet relatively little is known regarding effects on the heart. We induced pressure overload (PO) in mice and found that lipocalin-2 knockout (LKO) mice exhibited less PO-induced autophagy and NLRP3 inflammasome activation than Wt. PO-induced mitochondrial damage was reduced and autophagic flux greater in LKO mice, which correlated with less cardiac dysfunction. All of these observations were negated upon adenoviral-mediated restoration of normal lipocalin-2 levels in LKO. Studies in primary cardiac fibroblasts indicated that lipocalin-2 enhanced priming and activation of NLRP3-inflammasome, detected by increased IL-1β, IL-18 and Caspase-1 activation. This was attenuated in cells isolated from NLRP3-deficient mice or upon pharmacological inhibition of NLRP3. Furthermore, lipocalin-2 induced release of HMGB1 from cells and NLRP3-inflammasome activation was attenuated by TLR4 inhibition. We also found evidence of increased inflammasome activation and reduced autophagy in cardiac biopsy samples from heart failure patients. Overall, this study provides new mechanistic insight on the detrimental role of lipocalin-2 in the development of cardiac dysfunction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhn, M., E-mail: kuhnm@mit.edu; Hashimoto, S.; Sato, K.

The oxygen nonstoichiometry of La{sub 0.6}Sr{sub 0.4}CoO{sub 3-{delta}} has been the topic of various reports in the literature, but has been exclusively measured at high oxygen partial pressures, pO{sub 2}, and/or elevated temperatures. For applications of La{sub 0.6}Sr{sub 0.4}CoO{sub 3-{delta}}, such as solid oxide fuel cell cathodes or oxygen permeation membranes, knowledge of the oxygen nonstoichiometry and thermo-chemical stability over a wide range of pO{sub 2} is crucial, as localized low pO{sub 2} could trigger failure of the material and device. By employing coulometric titration combined with thermogravimetry, the oxygen nonstoichiometry of La{sub 0.6}Sr{sub 0.4}CoO{sub 3-{delta}} was measured at highmore » and intermediate pO{sub 2} until the material decomposed (at log(pO{sub 2}/bar) Almost-Equal-To -4.5 at 1073 K). For a gradually reduced sample, an offset in oxygen content suggests that La{sub 0.6}Sr{sub 0.4}CoO{sub 3-{delta}} forms a 'super-reduced' solid solution before decomposing. When the sample underwent alternate reduction-oxidation, a hysteresis-like pO{sub 2} dependence of the oxygen content in the decomposition pO{sub 2} range was attributed to the reversible formation of ABO{sub 3} and A{sub 2}BO{sub 4} phases. Reduction enthalpy and entropy were determined for the single-phase region and confirmed interpolated values from the literature. - Graphical abstract: Oxygen nonstoichiometry (shown as 3-{delta}) of La{sub 0.6}Sr{sub 0.4}CoO{sub 3-{delta}} as a function of pO{sub 2} at 773-1173 K. The experimental data were obtained by thermogravimetric analysis (TG) and coulometric titration (measured either by a simple reduction (CT1) or a 'two-step-forward one-step-back' reduction-oxidation (CT2) procedure). D1 and D2 denote the decomposition pO{sub 2}. The solid lines are the fit to the thermogravimetry and CT1 data. The dashed lines represent the non-equilibrium region where the sample shows a super-reduced state. Highlights: Black-Right-Pointing-Pointer Oxygen nonstoichiometry of La{sub 0.6}Sr{sub 0.4}CoO{sub 3-{delta}} at intermediate temperatures and p(O2). Black-Right-Pointing-Pointer Experimental confirmation of previously interpolated reduction enthalpy. Black-Right-Pointing-Pointer Decomposition p(O2) assessed by coulometric titration. Black-Right-Pointing-Pointer Hysteresis-like p(O2) dependence of oxygen content at decomposition p(O2).« less

The effects of slight pressure oscillations in the far infrasound frequency range on the pars flaccida in gerbil and rabbit ears.

PubMed

Didyk, L A; Bogdanov, V B; Lysenko, V A; Didyk, N P; Gorgo, Yu P; Dirckx, J J J

2007-01-01

This study was designed to clarify whether the pars flaccida (PF) as a flexible part of the tympanic membrane is capable of reacting to pressure oscillations (PO) with amplitudes and frequencies typical for natural atmospheric pressure fluctuations in the far infrasound frequency range (APF). If so, the PF mechanical reactions to APF might be involved in the overall physiologic regulation processes, which make organisms susceptible to APF. The displacements of the PF in response to PO were measured in vitro in ears of gerbils and rabbits by means of laser Doppler vibrometry. The index of the PF reactivity (R(a)) was determined as the ratio of the amplitude of the PF oscillations (PFO) to the amplitude of the PO. All kinds of PO applied caused PFO. The amplitude of the PFO increased when the amplitude of the PO was increased. In gerbils, a decrease in R(a) with the increase in amplitude of the PO was observed. In the range of PO lowest amplitudes (4-20 Pa) R(a) proved to be 1.4 times higher than in the range of highest amplitudes (90-105 Pa). Considering that the natural APF are usually within the range of +/-20 Pa, this fact points to an important contribution of the PF to the pressure dynamics in the middle ear (ME) of gerbils. In rabbit ears, R(a) was lower and recovery from plastic deformation was slower than in gerbils. Our findings are in line with the suggestion that the PF might play an important role in respect of adaptation to natural APF.

Highly conducting divalent Mg{sup 2+} cation solid electrolytes with well-ordered three-dimensional network structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamura, Shinji; Yamane, Megumi; Hoshino, Yasunori

2016-03-15

A three-dimensionally well-ordered NASICON-type Mg{sup 2+} cation conductor, (Mg{sub x}Hf{sub 1−x}){sub 4/(4−2x)}Nb(PO{sub 4}){sub 3}, was firstly developed by partial substitution of lower valent Mg{sup 2+} cation onto the Hf{sup 4+} sites in a HfNb(PO{sub 4}){sub 3} solid to realize high Mg{sup 2+} cation conductivity even at moderate temperatures. Due to the formation of well-ordered NASICON-type structure, both the high Mg{sup 2+} cation conductivity below 450 °C and the low activation energy for Mg{sup 2+} cation migration was successfully realized for the (Mg{sub 0.1}Hf{sub 0.9}){sub 4/3.8}Nb(PO{sub 4}){sub 3} solid. Pure Mg{sup 2+} cation conduction in the NASICON-type (Mg{sub 0.1}Hf{sub 0.9}){sub 4/3.8}Nb(PO{submore » 4}){sub 3} solid was directly and quantitatively demonstrated by means of two kinds of dc electrolysis. - Graphical abstract: Image of the Mg{sup 2+} cation conduction in NASICON-type (Mg{sub 0.1}Hf{sub 0.9}){sub 4/3.8}Nb(PO{sub 4}){sub 3} and its Mg{sup 2+} conductivity. - Highlights: • We develop a three-dimensionally well-ordered NASICON-type Mg{sup 2+} cation conductor. • A high magnesium cation conductivity is realized even at moderate temperatures. • Divalent magnesium cation conduction is demonstrated directly and quantitatively.« less

Ion chemistry of phosphorus in hydrocarbon flames : Part 1. electron scavenging by negative ion formation

NASA Astrophysics Data System (ADS)

Goodings, John M.; Hassanali, Carl S.

1990-12-01

Premixed methane--oxygen flames at atmospheric pressure of both fuel-rich (FR) and fuel-lean (FL; i.e. oxygen-rich) composition were doped with small amounts ( < 0.1 mol %) of volatile phosphorus alkyl triesters. It was demonstrated that these organo phosphorus compounds lead to efficient scavenging of the free electrons, normally present in the burnt gas of hydrocarbon flames, by negative ion formation. The anions produced by chemical ionization reactions were observed by sampling the flame gas through a nozzle into a mass spectrometer. Under both FR and FL conditions, the mass spectrum of phosphorus anions was dominated by PO-3, with a lesser contribution from PO-2. Also, H2PO-4 and PO- were observed below 100 u, as well as HPO-4 and PO-4 in the FL flame, and H2CPO-2 in the FR case. Above 100 u, the identity of the additive survivedin the FR flame to give anions of the type (RO)xPOy(OH)-z, where R is the alkyl group. However, these were replaced in the FL flame by anions of the type PO-n (n = 5-8) below 160 u. The formation chemistry of this considerable variety of phosphorus anions is discussed in detail, involving mainly three-body association, nucleophilic displacement (SN2) and proton abstraction reactions.

Radioecological modelling of Polonium-210 and Caesium-137 in lichen-reindeer-man and top predators.

PubMed

Persson, Bertil R R; Gjelsvik, Runhild; Holm, Elis

2018-06-01

This work deals with analysis and modelling of the radionuclides 210 Pb and 210 Po in the food-chain lichen-reindeer-man in addition to 210 Po and 137 Cs in top predators. By using the methods of Partial Least Square Regression (PLSR) the atmospheric deposition of 210 Pb and 210 Po is predicted at the sample locations. Dynamic modelling of the activity concentration with differential equations is fitted to the sample data. Reindeer lichen consumption, gastrointestinal absorption, organ distribution and elimination is derived from information in the literature. Dynamic modelling of transfer of 210 Pb and 210 Po to reindeer meat, liver and bone from lichen consumption, fitted well with data from Sweden and Finland from 1966 to 1971. The activity concentration of 210 Pb in the skeleton in man is modelled by using the results of studying the kinetics of lead in skeleton and blood in lead-workers after end of occupational exposure. The result of modelling 210 Pb and 210 Po activity in skeleton matched well with concentrations of 210 Pb and 210 Po in teeth from reindeer-breeders and autopsy bone samples in Finland. The results of 210 Po and 137 Cs in different tissues of wolf, wolverine and lynx previously published, are analysed with multivariate data processing methods such as Principal Component Analysis PCA, and modelled with the method of Projection to Latent Structures, PLS, or Partial Least Square Regression PLSR. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of uterine fundal pressure on the duration of the second stage of labor: a randomized controlled trial.

PubMed

Api, Olus; Balcin, Muge Emeksiz; Ugurel, Vedat; Api, Murat; Turan, Cem; Unal, Orhan

2009-01-01

To determine the effect of uterine fundal pressure on shortening the second stage of labor and on the fetal outcome. Randomized controlled trial. Teaching and research hospital. One hundred ninety-seven women between 37 and 42 gestational weeks with singleton cephalic presentation admitted to the delivery unit. Random allocation into groups with or without manual fundal pressure during the second stage of labor. The primary outcome measure was the duration of the second stage of labor. Secondary outcome measures were umbilical artery pH, HCO3-, base excess, pO2, pCO2 values and the rate of instrumental delivery, severe maternal morbidity/mortality, neonatal trauma, admission to neonatal intensive care unit, and neonatal death. There were no significant differences in the mean duration of the second stage of labor and secondary outcome measures except for mean pO2 which was lower and mean pCO2 which was higher in the fundal pressure group. Nevertheless, the values still remained within normal ranges and there were no neonates with an Apgar score <7 in either of the groups. Application of fundal pressure on a delivering woman was ineffective in shortening the second stage of labor.

Stability of Silica- and Enzyme-Treated Palm Oil Under Deep Frying Conditions.

PubMed

Karim, Nur Azwani Ab; Noor, Ahmadilfitri Md; Lee, Yee-Ying; Lai, Oi-Ming

2015-12-01

The oxidative and thermal stability of low diglycerides palm oil produced via silica treatment (sPO) and enzymatic treatment (ePO) compared with standard quality palm oil (SQ) and premium quality palm oil (PQ) was investigated. Both of the oils displayed better oxidative stability compared with SQ as well as significantly higher (P < 0.05) thermal resistance and oxidative strength than SQ and PQ due to lower amounts of partial glycerides. Although the initial induction periods (IPs) of sPO and ePO were significantly lower compared with SQ and PQ, both the oils showed slower drops in their IP values. The darkening effect after frying was significantly (P < 0.05) slower in sPO compared with SQ, PQ, and ePO. Besides, there is no difference p > 0.05 in the rate of FFA formation between sPO and PQ. The anisidine value and peroxide values were lowest in sPO, followed by ePO, PQ, and SQ. © 2015 Institute of Food Technologists®

Oxygenation and ventilation characteristics in obese sedated dogs before and after weight loss: a clinical trial.

PubMed

Mosing, M; German, A J; Holden, S L; MacFarlane, P; Biourge, V; Morris, P J; Iff, I

2013-11-01

This prospective clinical study examined the effect of obesity and subsequent weight loss on oxygenation and ventilation during deep sedation in pet dogs. Data from nine dogs completing a formalised weight loss programme were evaluated. Dual-energy X-ray absorptiometry (DEXA) was used to quantify body fat mass prior to and after weight loss. Dogs were deeply sedated and positioned in dorsal recumbency. Sedation was scored using a semi-objective scheme. As part of the monitoring of sedation, arterial oxygen partial pressure (PaO2) and arterial carbon dioxide partial pressure (PaCO2) were measured after 10 min in dorsal recumbency. Oxygen saturation of haemoglobin (SpO2) was monitored continuously using pulse oximetry, starting oxygen supplementation where indicated (SpO2<90%) via a face mask. Morphometric measurements were taken from DEXA images and compared before and after weight loss. Several oxygen indices were calculated and correlated with body fat variables evaluated by DEXA. All body fat variables improved significantly after weight loss. PaO2 increased from 27.9±19.2 kPa to 34.8±24.4 kPa, while FiO2 decreased from 0.74±0.31 to 0.66±0.35. Morphometric measurements improved significantly after weight loss. PaO2/FiO2 (inspired oxygen fraction) and Pa/AO2 (ratio of PaO2 to alveolar PO2) also improved significantly, but there was no change in f-shunt and PaCO2 after weight loss. On multiple linear regression analysis, all oxygen indices were negatively associated with thoracic fat percentage. In conclusion, obesity decreases oxygenation in dogs during deep sedation. Oxygenation status improves with successful weight loss, but ventilation is not influenced by obesity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Phenoloxidase activity in the infraorder Isoptera: unraveling life-history correlates of immune investment

NASA Astrophysics Data System (ADS)

Rosengaus, Rebeca B.; Reichheld, Jennifer L.

2016-02-01

Within the area of ecological immunology, the quantification of phenoloxidase (PO) activity has been used as a proxy for estimating immune investment. Because termites have unique life-history traits and significant inter-specific differences exist regarding their nesting and foraging habits, comparative studies on PO activity can shed light on the general principles influencing immune investment against the backdrop of sociality, reproductive potential, and gender. We quantified PO activity across four termite species ranging from the phylogenetically basal to the most derived, each with their particular nesting/foraging strategies. Our data indicate that PO activity varies across species, with soil-dwelling termites exhibiting significantly higher PO levels than the above-ground wood nester species which in turn have higher PO levels than arboreal species. Moreover, our comparative approach suggests that pathogenic risks can override reproductive potential as a more important driver of immune investment. No gender-based differences in PO activities were recorded. Although termite PO activity levels vary in accordance with a priori predictions made from life-history theory, our data indicate that nesting and foraging strategies (and their resulting pathogenic pressures) can supersede reproductive potential and other life-history traits in influencing investment in PO. Termites, within the eusocial insects, provide a unique perspective for inferring how different ecological pressures may have influenced immune function in general and their levels of PO activity, in particular.

Mechanism and Kinetics of Ethanol Coupling to Butanol over Hydroxyapatite

DOE PAGES

Ho, Christopher R.; Shylesh, Sankaranarayanapillai; Bell, Alexis T.

2015-12-23

The mechanism and kinetics for ethanol coupling to n-butanol over hydroxyapatite (HAP) were investigated at 573-613 K. In situ titration experiments show that the active sites for acetaldehyde and butanol formation are different. In combination with FTIR studies, it was found that ethanol dehydrogenation is catalyzed by Ca-O sites, whereas condensation of acetaldehyde is catalyzed by CaO/PO 4 3- pairs. Measurements of the reaction kinetics at various ethanol (3.5-9.4 kPa) and acetaldehyde (0.055-0.12 kPa) partial pressures reveal that direct condensation involving two ethanol molecules does not play a significant role in butanol formation; instead, n-butanol is formed via a Guerbetmore » pathway. At a constant acetaldehyde pressure, enolate formation is rate-limiting, and ethanol inhibits acetaldehyde condensation rates by competitive adsorption. A model of the reaction kinetics consistent with all experimental observations is developed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, Christopher R.; Shylesh, Sankaranarayanapillai; Bell, Alexis T.

The mechanism and kinetics for ethanol coupling to n-butanol over hydroxyapatite (HAP) were investigated at 573-613 K. In situ titration experiments show that the active sites for acetaldehyde and butanol formation are different. In combination with FTIR studies, it was found that ethanol dehydrogenation is catalyzed by Ca-O sites, whereas condensation of acetaldehyde is catalyzed by CaO/PO 4 3- pairs. Measurements of the reaction kinetics at various ethanol (3.5-9.4 kPa) and acetaldehyde (0.055-0.12 kPa) partial pressures reveal that direct condensation involving two ethanol molecules does not play a significant role in butanol formation; instead, n-butanol is formed via a Guerbetmore » pathway. At a constant acetaldehyde pressure, enolate formation is rate-limiting, and ethanol inhibits acetaldehyde condensation rates by competitive adsorption. A model of the reaction kinetics consistent with all experimental observations is developed.« less

Sapwood development in Pinus radiata trees grown for three years at ambient and elevated carbon dioxide partial pressures.

PubMed

Atwell, B J; Henery, M L; Whitehead, D

2003-01-01

Clonal trees of Pinus radiata D. Don were grown in open-top chambers at a field site in New Zealand for 3 years at ambient (37 Pa) or elevated (65 Pa) carbon dioxide (CO2) partial pressure. Nitrogen (N) was supplied to half of the trees in each CO2 treatment, at 15 g N m-2 in the first year and 60 g N m-2 in the subsequent 2 years (high-N treatment). Trees in the low-N treatment were not supplied with N but received the same amount of other nutrients as trees in the high-N treatment. In the first year, stem basal area increased more in trees growing at elevated CO2 partial pressure and high-N supply than in control trees, suggesting a positive interaction between these resources. However, the relative rate of growth became the same across trees in all treatments after 450 days, resulting in trees growing at elevated CO2 partial pressure and high-N supply having larger basal areas than trees in the other treatments. Sapwood N content per unit dry mass was consistently about 0.09% in all treatments, indicating that N status was not suppressed by elevated CO2 partial pressure. Thus, during the first year of growth, an elevated CO2 partial pressure enhanced carbon (C) and N storage in woody stems, but there was no further stimulus to C and N deposition after the first year. The chemical composition of sapwood was unaffected by elevated CO2 partial pressure, indicating that no additional C was sequestered through lignification. However, independent of the treatments, early wood was 13% richer in lignin than late wood. Elevated CO2 partial pressure decreased the proportion of sapwood occupied by the lumina of tracheids by up to 12%, indicating increased sapwood density in response to CO2 enrichment. This effect was probably a result of thicker tracheid walls rather than narrower lumina.

Growth control of the oxidation state in vanadium oxide thin films

NASA Astrophysics Data System (ADS)

Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

2014-12-01

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

PubMed Central

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

Objective The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin. PMID:27096671

An ab-initio study of the energetics and geometry of sulfide, sulfite and sulfate incorporation into apatite: The thermodynamic basis for using this system as an oxybarometer

NASA Astrophysics Data System (ADS)

Kim, Y.; Konecke, B.; Fiege, A.; Simon, A. C.; Becker, U.

2017-12-01

We use ab-initio calculations to investigate the energetics and geometry of incorporation of S with its oxidation states S6+, S4+, and S2- into the apatite end-members fluor-, chlor-, and hydroxylapatite, [Ca10(PO4)6(F,Cl,OH)2]. The reaction energy of the balanced equation indicates the stability of the modeled S-incorporated apatite relative to the host apatite, the source, and sink phases. One possible coupled substitution mechanism involves the replacement of La3+ + PO43- ↔ Ca2+ + SO42-. Our results show that the incorporation of SO42- into La- and Na-bearing apatite, Ca8NaLa(PO4)6(F,Cl,OH)2, is energetically favored over the incorporation into La- and Si-bearing apatite, Ca9La(PO4)5(SiO4)(F,Cl,OH)2. Co-incorporation of SO42- and SO32- is energetically favored when the lone pair electrons of SO32- face towards the anion column site, compared to facing away from it. Full or partial incorporation of S2- is favored on the column anion site in the form of [Ca10(PO4)6S] and [Ca20(PO4)12SX2)], where X = F, Cl, or OH. Upon full incorporation (i.e., replacing all column ions by sulfide ions), S2- is positioned in the anion column at z = 0.5 (half way between the mirror planes at z = 1/4 and z = 3/4) in the energy-optimized structure. The calculated energies for partial incorporation of S2- demonstrate that in an energy-optimized structure, S2- is displaced from the mirror plane at z = 1/4 or 3/4, by 1.0 to 1.6 Å, depending on the surrounding species (F-, Cl- or OH-); however, the probability for S2- to be incorporated into the apatite structure is highest for chlorapatite end-members. Our results describe energetically feasible incorporation mechanisms for all three oxidations states of S (S6+, S4+, S2-) in apatite, along with structural distortion and concurring electronic structure changes. These observations are consistent with recently published experimental results (Konecke et al. 2017) that demonstrate S6+, S4+ and S2- incorporation into apatite, where the ratio of S6+/∑S in apatite is controlled by oxygen fugacity (fO2). The new computational results coupled with published experimental data provide the basis for using S in apatite as a geochemical proxy to trace variations in oxygen fugacity of magmatic and magmatic-hydrothermal systems.

46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154.405 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Containment Systems §...

46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154.405 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Containment Systems §...

46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154.405 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Containment Systems §...

46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154.405 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Containment Systems §...

Effects of oxygen partial pressure on Li-air battery performance

NASA Astrophysics Data System (ADS)

Kwon, Hyuk Jae; Lee, Heung Chan; Ko, Jeongsik; Jung, In Sun; Lee, Hyun Chul; Lee, Hyunpyo; Kim, Mokwon; Lee, Dong Joon; Kim, Hyunjin; Kim, Tae Young; Im, Dongmin

2017-10-01

For application in electric vehicles (EVs), the Li-air battery system needs an air intake system to supply dry oxygen at controlled concentration and feeding rate as the cathode active material. To facilitate the design of such air intake systems, we have investigated the effects of oxygen partial pressure (≤1 atm) on the performance of the Li-air cell, which has not been systematically examined. The amounts of consumed O2 and evolved CO2 from the Li-air cell are measured with a custom in situ differential electrochemical gas chromatography-mass spectrometry (DEGC-MS). The amounts of consumed O2 suggest that the oxygen partial pressure does not affect the reaction mechanism during discharge, and the two-electron reaction occurs under all test conditions. On the other hand, the charging behavior varies by the oxygen partial pressure. The highest O2 evolution ratio is attained under 70% O2, along with the lowest CO2 evolution. The cell cycle life also peaks at 70% O2 condition. Overall, an oxygen partial pressure of about 0.5-0.7 atm maximizes the Li-air cell capacity and stability at 1 atm condition. The findings here indicate that the appropriate oxygen partial pressure can be a key factor when developing practical Li-air battery systems.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, Rainer; Hauss, Helena; Buchholz, Friedrich; Melzner, Frank

2016-04-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2, and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply could fuel bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean considerably. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a down-regulation of ammonium excretion. We exposed calanoid copepods from the Eastern Tropical North Atlantic (ETNA; Undinula vulgaris and Pleuromamma abdominalis) and euphausiids from the Eastern Tropical South Pacific (ETSP; Euphausia mucronata) and the ETNA (Euphausia gibboides) to different temperatures, carbon dioxide and oxygen levels to study their survival, respiration and excretion rates at these conditions. An increase in temperature by 10 °C led to an approximately 2-fold increase of the respiration and excretion rates of U. vulgaris (Q10, respiration = 1.4; Q10, NH4-excretion = 1.6), P. abdominalis (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4) and E. gibboides (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4; E. mucronata not tested). Exposure to differing carbon dioxide levels had no overall significant impact on the respiration or excretion rates. Species from the ETNA were less tolerant to low oxygen levels than E. mucronata from the ETSP, which survived exposure to anoxia at 13 °C. Respiration and excretion rates were reduced upon exposure to low oxygen levels, albeit at different species-specific levels. Reduction of the excretion and respiration rates in ETNA species occurred at a pO2 of 0.6 (P. abdominalis) and 2.4 kPa (U. vulgaris and E. gibboides) at OMZ temperatures. Such low oxygen levels are normally not encountered by these species in the ETNA. E. mucronata however regularly migrates into the strongly hypoxic to anoxic core of the ETSP OMZ. Exposure to low oxygen levels led to a strong reduction of respiration and ammonium excretion in E. mucronata (pcrit respiration = 0.6, pcrit NH4-excretion = 0.73). A drastic reduction of respiratory activity was also observed by other authors for euphausiids, squat lobsters and calanoid copepods, but was not yet accounted for when calculating DVM-mediated active fluxes into the ETSP OMZ. Current estimates of DVM-mediated active export of carbon and nitrogen into the ETSP OMZ are therefore likely too high and future efforts to calculate these export rates should take the physiological responses of migratory species to OMZ conditions into account.

The Growth of Berlinite (AlPO4) Single Crystals.

DTIC Science & Technology

1980-03-01

Solubility of AlPO 4 18 6. Solubility Data of Jahn and Kordes on AlPO4 19 7. AlPO 4 Seed Crystal 23 8. Tem-Pres Hydrothermal Research Unit 25 9...Since the vapor pressure of water rises rapidly with temperature, a closed hydrothermal system was used. In a seeded hydrothermal growth process, the...to investigate the hydrothermal growth of Berlinite (AlPO4 ) to determine the optimum growth conditions for large high quality crystals. Over thirty

Oxygen sensing PLIM together with FLIM of intrinsic cellular fluorophores for metabolic mapping

NASA Astrophysics Data System (ADS)

Kalinina, Sviatlana; Schaefer, Patrick; Breymayer, Jasmin; Bisinger, Dominik; Chakrabortty, Sabyasachi; Rueck, Angelika

2018-02-01

Otical imaging techniques based on time correlated single photon counting (TCSPC) has found wide applications in medicine and biology. Non-invasive and information-rich fluorescence lifetime imaging microscopy (FLIM) is successfully used for monitoring fluorescent intrinsic metabolic coenzymes as NAD(P)H (nicotinamide adenine dinucleotide (phosphate)) and FAD+ (flavin adenine dinucleotide) in living cells and tissues. The ratio between proteinbound and free coenzymes gives an information about the balance between oxidative phosphorylation and glycolysis in the cells. The changes of the ratio reflects major cellular disorders. A correlation exists between metabolic activity, redox ratio and fluorescence lifetime during stem cell differentiation, neurodegenerative diseases, and carcinogenesis. A multichannel FLIM detection system was designed for monitoring the redox state of NAD(P)H and FAD+ and other intrinsic fluorophores as protoporphyrin IX. In addition, the unique upgrade is useful to perform FLIM and PLIM (phosphorescence lifetime imaging microscopy) simultaneously. PLIM is a promising method to investigate oxygen sensing in biomedical samples. In detail, the oxygen-dependent quenching of phosphorescence of some compounds as transition metal complexes enables measuring of oxygen partial pressure (pO2). Using a two-channel FLIM/PLIM system we monitored intrinsic pO2 by PLIM simultaneously with NAD(P)H by FLIM providing complex metabolic and redox imaging of living cells. Physico-chemical properties of oxygen sensitive probes define certain parameters including their localisation. We present results of some ruthenium based complexes including those specifically bound to mitochondria.

EPR Oximetry for Investigation of Hyperbaric O2 Pre-treatment for Tumor Radiosensitization.

PubMed

Williams, Benjamin B; Hou, Huagang; Coombs, Rachel; Swartz, Harold M

A number of studies have reported benefits associated with the application of hyperbaric oxygen treatment (HBO) delivered immediately prior to radiation therapy. While these studies provide evidence that pre-treatment with HBO may be beneficial, no measurements of intratumoral pO2 were carried out and they do not directly link the apparent benefits to decreased hypoxic fractions at the time of radiation therapy. While there is empirical evidence and some theoretical basis for HBO to enhance radiation therapy, without direct and repeated measurements of its effects on pO2, it is unlikely that the use of HBO can be understood and optimized for clinical applications. In vivo EPR oximetry is a technique uniquely capable of providing repeated direct measurements of pO2 through a non-invasive procedure in both animal models and human patients. In order to evaluate the ability of pretreatment with HBO to elevate tumor pO2, a novel small animal hyperbaric chamber system was constructed that allows simultaneous in vivo EPR oximetry. This chamber can be placed within the EPR magnet and is equipped with a variety of ports for multiplace gas delivery, thermoregulation, delivery of anesthesia, physiologic monitoring, and EPR detection. Initial measurements were performed in a subcutaneous RIF-1 tumor model in C3H/HeJ mice. The mean baseline pO2 value was 6.0 ± 1.2 mmHg (N = 7) and responses to two atmospheres absolute pressure HBO varied considerably across subjects, within tumors, and over time. When an increase in pO2 was observed, the effect was transient in all but one case, with durations lasting from 5 min to over 20 min, and returned to baseline levels during HBO administration. These results indicate that without direct measurements of pO2 in the tissue of interest, it is likely to be difficult to know the effects of HBO on actual tissue pO2.

Infrared and Raman Spectra of Magnesium Ammonium Phosphate Hexahydrate (Struvite) and its Isomorphous Analogues. VIII. Spectra of Protiated and Partially Deuterated Magnesium Rubidium Phosphate Hexahydrate and Magnesium Thallium Phosphate Hexahydrate.

PubMed

Soptrajanov, Bojan; Cahil, Adnan; Najdoski, Metodija; Koleva, Violeta; Stefov, Viktor

2011-09-01

The infrared and Raman spectra of magnesium rubidium phosphate hexahydrate MgRbPO4 • 6H2O and magnesium thallium phosphate hexahydrate, MgTlPO4 • 6H2O were recorded at room temperature (RT) and the boiling temperature of liquid nitrogen (LNT). To facilitate their analysis, also recorded were the spectra of partially deuterated analogues with varying content of deuterium. The effects of deuteration and those of lowering the temperature were the basis of the conclusions drawn regarding the origin of the observed bands which were assigned to vibrations which are predominantly localized in the water molecules (four crystallographically different types of such molecules exist in the structures) and those with PO43- character. It was concluded that in some cases coupling of phosphate and water vibrations is likely to take place. The appearance of the infrared spectra in the O-H stretching regions of the infrared spectra is explained as being the result of an extensive overlap of bands due to components of the fundamental stretching modes of the H2O units with a possible participation of bands due to second-order transitions. A broad band reminiscent of the B band of the well-known ABC trio characteristic of spectra of substances containing strong hydrogen bonds in their structure was found around 2400 cm-1 in the infrared spectra of the two studied compounds.

Ilizarov external fixation versus plate osteosynthesis in the management of extra-articular fractures of the distal tibia.

PubMed

Fadel, Mohamed; Ahmed, Mohamed Ali; Al-Dars, Ahmed Mounir; Maabed, Mustafa Ahmed; Shawki, Hashem

2015-03-01

The purpose of this study was to evaluate the outcome of Ilizarov external fixation (IE) versus dynamic compression plate (PO) in the management of extra-articular distal tibial fractures. Between 2010 and 2011, extra-articular distal tibial fractures in 40 consecutive patients met the inclusion criteria. They were classified according to AO classification fracture type A (A1, A2, and A3). In a randomized method, two equal groups were managed using either IE or PO. PO was performed using open reduction and internal fixation (ORIF) and DCP through anterolateral approach. IE was done using Ilizarov frame. For the PO group, non-weight bearing ambulation was permitted on the second postoperative day but partial weight bearing was permitted according to the progression in union criteria clinically and radiologically. For the IE group, weight bearing started as tolerated from the first postoperative day. Physiotherapy and pin-site care was performed by the patient themselves. Modified Mazur ankle score was applied to IE (excellent 10, good 10) and in PO (excellent 2, good 8, poor 6). Data were statically analysed using (Mann-Whitney test). The rate of healing in the IE group (average 130) was higher than the PO (average 196.5); plus, there were no cases of delayed union or nonunion in the IE group (p value 0.003). It was found that IE compared with PO provides provision of immediate weight bearing as tolerated following postoperative recovery, irrespective of radiological or clinical healing with no infection, deformity or non-union.

Acclimatization and tolerance to extreme altitude

NASA Technical Reports Server (NTRS)

West, J. B.

1993-01-01

During the last ten years, two major experiments have elucidated the factors determining acclimatization and tolerance to extreme altitude (over 7000 m). These were the American Medical Research Expedition to Everest, and the low pressure chamber simulation, Operation Everest II. Extreme hyperventilation is one of the most important responses to extreme altitude. Its chief value is that it allows the climber to maintain an alveolar PO2 which keeps the arterial PO2 above dangerously low levels. Even so, there is evidence of residual impairment of central nervous system function after ascents to extreme altitude, and maximal oxygen consumption falls precipitously above 7000 m. The term 'acclimatization' is probably not appropriate for altitudes above 8000 m, because the body steadily deteriorates at these altitudes. Tolerance to extreme altitude is critically dependent on barometric pressure, and even seasonal changes in pressure probably affect climbing performance near the summit of Mt Everest. Supplementary oxygen always improves exercise tolerance at extreme altitudes, and rescue oxygen should be available on climbing expeditions to 8000 m peaks.

Using the time-to-event continual reassessment method in the presence of partial orders

PubMed Central

Wages, Nolan A.; Conaway, Mark R.; O'Quigley, John

2012-01-01

The time-to-event continual reassessment method (TITE-CRM) was proposed to handle the problem of long trial duration in Phase 1 trials as a result of late-onset toxicities. Here, we implement the TITE-CRM in dose–finding trials of combinations of agents. When studying multiple agents, monotonicity of the dose-toxicity curve is not clearly defined. Therefore, the toxicity probabilities follow a partial order, meaning that there are pairs of treatments for which the ordering of the toxicity probabilities is not known at the start of the trial. A CRM design for partially ordered trials (PO-CRM) was recently proposed. Simulation studies show that extending the TITE-CRM to the partial order setting produces results similar to those of the PO-CRM in terms of maximum tolerated dose recommendation yet reduces the duration of the trial. PMID:22806898

Magnetism in olivine-type LiCo(1-x)Fe(x)PO4 cathode materials: bridging theory and experiment.

PubMed

Singh, Vijay; Gershinsky, Yelena; Kosa, Monica; Dixit, Mudit; Zitoun, David; Major, Dan Thomas

2015-12-14

In the current paper, we present a non-aqueous sol-gel synthesis of olivine type LiCo1-xFexPO4 compounds (x = 0.00, 0.25, 0.50, 0.75, 1.00). The magnetic properties of the olivines are measured experimentally and calculated using first-principles theory. Specifically, the electronic and magnetic properties are studied in detail with standard density functional theory (DFT), as well as by including spin-orbit coupling (SOC), which couples the spin to the crystal structure. We find that the Co(2+) ions exhibit strong orbital moment in the pure LiCoPO4 system, which is partially quenched upon substitution of Co(2+) by Fe(2+). Interestingly, we also observe a non-negligible orbital moment on the Fe(2+) ion. We underscore that the inclusion of SOC in the calculations is essential to obtain qualitative agreement with the observed effective magnetic moments. Additionally, Wannier functions were used to understand the experimentally observed rising trend in the Néel temperature, which is directly related to the magnetic exchange interaction paths in the materials. We suggest that out of layer M-O-P-O-M magnetic interactions (J⊥) are present in the studied materials. The current findings shed light on important differences observed in the electrochemistry of the cathode material LiCoPO4 compared to the already mature olivine material LiFePO4.

[Monitoring the oxygen supply of skeletal muscle and total oxygen uptake in coronary surgery interventions].

PubMed

Boekstegers, P; Fleckenstein, W; Rosport, A; Ruschewsky, W; Braun, U

1988-05-01

In patients undergoing aortocoronary bypass operations, extensive monitoring is used for early recognition of complications that may decrease the oxygen supply of body organs. However, none of the parameters usually monitored during open-heart surgery yield information on the state of oxygen supply to a certain organ. Particularly during and after extracorporeal circulation (ECC), undetected organ hypoxia may occur and lead to an increase in postoperative complications. In order to study whether functionally significant changes in oxygen supply to skeletal muscle occur during extracorporeal circulation, in 14 patients undergoing aortocoronary bypass operations pO2 histograms from local pO2 values in resting skeletal muscle were monitored. Intra- and postoperatively, whole-body oxygen uptake (VO2) and pO2 histograms of skeletal muscle were simultaneously measured to determine whether the observed decrease in VO2 during cooling of the patient or the increase in VO2 during rewarming was reflected in the distribution of tissue pO2 in skeletal muscle. PATIENTS AND METHODS. Fourteen patients (aged 42 to 68; 12 male, 2 female) scheduled for 2-4 aortocoronary venous bypass grafts were studied. Measuring periods of 6 min were undertaken after induction of anesthesia (1), after thoracotomy (2), during ECC (3), after ECC (2), and every hour postoperatively up to 5 h. The following data were measured during each period: pO2 histograms of the biceps brachii muscle using a pO2 histograph VO2 using open indirect calorimetry; arterial (a. radialis) and venous (v. cava superior) blood gases, acid-base balances, and blood pressures; venous lactate (v. cava superior); muscle and rectal temperatures. RESULTS. During ECC mean muscle pO2 in all 14 patients decreased from 25 to 14 mmHg. In 7 of 14 patients pO2 values between 0 and 5 mmHg had the highest incidence (left-shifted pO2 histograms). After ECC mean muscle pO2 increased to the same value observed before ECC (25 mmHg). During the first 3 h postoperatively an intermediate decrease in mean muscle pO2 (range 23%-46%) occurred in each patient. Stable values above 20 mmHg were reattained 4 h postoperatively. The postoperative increase in individual VO2 was correlated to the increase in body temperature (r = 0.84); in 5 patients with severe shivering, VO2 was markedly increased (up to 130% compared to the last intraoperative value).(ABSTRACT TRUNCATED AT 400 WORDS)

STAT3 Activation in Pressure-Overloaded Feline Myocardium: Role for Integrins and the Tyrosine Kinase BMX

PubMed Central

Willey, Christopher D.; Palanisamy, Arun P.; Johnston, Rebecca K.; Mani, Santhosh K.; Shiraishi, Hirokazu; Tuxworth, William J.; Zile, Michael R.; Balasubramanian, Sundaravadivel; Kuppuswamy, Dhandapani

2008-01-01

Growth, survival and cytoskeletal rearrangement of cardiomyocytes are critical for cardiac hypertrophy. Signal transducer and activator of transcription-3 (STAT3) activation is an important cardioprotective factor associated with cardiac hypertrophy. Although STAT3 activation has been reported via signaling through Janus Kinase 2 (JAK2) in several cardiac models of hypertrophy, the importance of other nonreceptor tyrosine kinases (NTKs) has not been explored. Utilizing an in vivo feline right ventricular pressure-overload (RVPO) model of hypertrophy, we demonstrate that in 48 h pressure-overload (PO) myocardium, STAT3 becomes phosphorylated and redistributed to detergent-insoluble fractions with no accompanying JAK2 activation. PO also caused increased levels of phosphorylated STAT3 in both cytoplasmic and nuclear fractions. To investigate the role of other NTKs, we used our established in vitro cell culture model of hypertrophy where adult feline cardiomyocytes are embedded three-dimensionally (3D) in type-I collagen and stimulated with an integrin binding peptide containing an Arg-Gly-Asp (RGD) motif that we have previously shown to recapitulate the focal adhesion complex (FAC) formation of 48 h RVPO. RGD stimulation of adult cardiomyocytes in vitro caused both STAT3 redistribution and activation that were accompanied by the activation and redistribution of c-Src and the TEC family kinase, BMX, but not JAK2. However, infection with dominant negative c-Src adenovirus was unable to block RGD-stimulated changes on either STAT3 or BMX. Further analysis in vivo in 48 h PO myocardium showed the presence of both STAT3 and BMX in the detergent-insoluble fraction with their complex formation and phosphorylation. Therefore, these studies indicate a novel mechanism of BMX-mediated STAT3 activation within a PO model of cardiac hypertrophy that might contribute to cardiomyocyte growth and survival. PMID:18612371

31 CFR 100.11 - Exchange of bent and partial coins.

Code of Federal Regulations, 2013 CFR

2013-07-01

... partial coins shall be presented separately by denomination category in lots of at least one pound for... redeemed at the face value equivalent of copper one cent coins. (c) Redemption site. Bent and partial coins will be redeemed only at the United States Mint, P.O. Box 400, Philadelphia, PA 19105. Coins are...

Oxygen partial pressure influenced structural and optical properties of DC magnetron sputtered ZrO{sub 2} films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kondaiah, P.; Madhavi, V.; Uthanna, S.

2013-02-05

Thin films of zirconium oxide (ZrO{sub 2}) were deposited on (100) p-silicon and quartz substrates by sputtering of metallic zirconium target under different oxygen partial pressures in the range 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa. The effect of oxygen partial pressure on the structural and optical properties of the deposited films was systematically investigated. The deposition rate of the films decreased from 3.3 to 1.83 nm/min with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively. The X-ray diffraction profiles revealed that the films exhibit (111) refection of zirconium oxide in monoclinic phase.more » The optical band gap of the films increased from 5.62 to 5.80 eV and refractive index increased from 2.01 to 2.08 with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively.« less

Impact of Pancreatic Rat Islet Density on Cell Survival during Hypoxia

PubMed Central

Rodriguez-Brotons, A.; Bietiger, W.; Peronet, C.; Magisson, J.; Sookhareea, C.; Langlois, A.; Mura, C.; Jeandidier, N.; Pinget, M.; Sigrist, S.; Maillard, E.

2016-01-01

In bioartificial pancreases (BP), the number of islets needed to restore normoglycaemia in the diabetic patient is critical. However, the confinement of a high quantity of islets in a limited space may impact islet survival, particularly in regard to the low oxygen partial pressure (PO2) in such environments. The aim of the present study was to evaluate the impact of islet number in a confined space under hypoxia on cell survival. Rat islets were seeded at three different concentrations (150, 300, and 600 Islet Equivalents (IEQ)/cm2) and cultured in normal atmospheric pressure (160 mmHg) as well as hypoxic conditions (15 mmHg) for 24 hours. Cell viability, function, hypoxia-induced changes in gene expression, and cytokine secretion were then assessed. Notably, hypoxia appeared to induce a decrease in viability and increasing islet density exacerbated the observed increase in cellular apoptosis as well as the loss of function. These changes were also associated with an increase in inflammatory gene transcription. Taken together, these data indicate that when a high number of islets are confined to a small space under hypoxia, cell viability and function are significantly impacted. Thus, in order to improve islet survival in this environment during transplantation, oxygenation is of critical importance. PMID:26824040

Heart Rate and Oxygen Saturation Change Patterns During 6-min Walk Test in Subjects With Chronic Thromboembolic Pulmonary Hypertension.

PubMed

Inagaki, Takeshi; Terada, Jiro; Yahaba, Misuzu; Kawata, Naoko; Jujo, Takayuki; Nagashima, Kengo; Sakao, Seiichiro; Tanabe, Nobuhiro; Tatsumi, Koichiro

2018-05-01

The 6-min walk test (6MWT) is commonly performed to assess functional status in patients with chronic thromboembolic pulmonary hypertension. However, changes in heart rate and oxygen saturation (S pO 2 ) patterns during 6MWT in patients with chronic thromboembolic pulmonary hypertension remain unclear. Thirty-one subjects with chronic thromboembolic pulmonary hypertension were retrospectively evaluated to examine the relationships between the change in heart rate (Δheart rate), heart rate acceleration time, slope of heart rate acceleration, heart rate recovery during the first minute after 6MWT (HRR1), change in S pO 2 (ΔS pO 2 ), S pO 2 reduction time, and S pO 2 recovery time during 6MWT, and the severity of pulmonary hemodynamics assessed by right heart catheterization and echocardiography. Subjects with severe chronic thromboembolic pulmonary hypertension had significantly longer heart rate acceleration time (144.9 ± 63.9 s vs 96.0 ± 42.5 s, P = .033), lower Δheart rate (47.4 ± 16.9 vs 61.8 ± 13.6 beats, P = .02), and lower HRR1 (13.3 ± 9.0 beats vs 27.1 ± 9.2 beats, P < .001) compared to subjects with mild chronic thromboembolic pulmonary hypertension. Subjects with severe chronic thromboembolic pulmonary hypertension also had significantly longer S pO 2 reduction time (178.3 ± 70.3 s vs 134.3 ± 58.4 s, P = .03) and S pO 2 recovery time (107.6 ± 35.3 s vs 69.8 ± 32.7 s, P = .004) than did subjects with mild chronic thromboembolic pulmonary hypertension. Multivariate linear regression analysis showed only mean pulmonary arterial pressure independently was associated with heart rate acceleration time and slope of heart rate acceleration. Heart rate and S pO 2 change patterns during 6MWT are predominantly associated with pulmonary hemodynamics in subjects with chronic thromboembolic pulmonary hypertension. Evaluating heart rate and S pO 2 change patterns during 6MWT may serve as a safe and convenient way to follow the change in pulmonary hemodynamics. Copyright © 2018 by Daedalus Enterprises.

EVP-6124, a novel and selective α7 nicotinic acetylcholine receptor partial agonist, improves memory performance by potentiating the acetylcholine response of α7 nicotinic acetylcholine receptors.

PubMed

Prickaerts, Jos; van Goethem, Nick P; Chesworth, Richard; Shapiro, Gideon; Boess, Frank G; Methfessel, Christoph; Reneerkens, Olga A H; Flood, Dorothy G; Hilt, Dana; Gawryl, Maria; Bertrand, Sonia; Bertrand, Daniel; König, Gerhard

2012-02-01

EVP-6124, (R)-7-chloro-N-quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide, is a novel partial agonist of α7 neuronal nicotinic acetylcholine receptors (nAChRs) that was evaluated here in vitro and in vivo. In binding and functional experiments, EVP-6124 showed selectivity for α7 nAChRs and did not activate or inhibit heteromeric α4β2 nAChRs. EVP-6124 had good brain penetration and an adequate exposure time. EVP-6124 (0.3 mg/kg, p.o.) significantly restored memory function in scopolamine-treated rats (0.1 mg/kg, i.p.) in an object recognition task (ORT). Although donepezil at 0.1 mg/kg, p.o. or EVP-6124 at 0.03 mg/kg, p.o. did not improve memory in this task, co-administration of these sub-efficacious doses fully restored memory. In a natural forgetting test, an ORT with a 24 h retention time, EVP-6124 improved memory at 0.3 mg/kg, p.o. This improvement was blocked by the selective α7 nAChR antagonist methyllycaconitine (0.3 mg/kg, i.p. or 10 μg, i.c.v.). In co-application experiments of EVP-6124 with acetylcholine, sustained exposure to EVP-6124 in functional investigations in oocytes caused desensitization at concentrations greater than 3 nM, while lower concentrations (0.3-1 nM) caused an increase in the acetylcholine-evoked response. These actions were interpreted as representing a co-agonist activity of EVP-6124 with acetylcholine on α7 nAChRs. The concentrations of EVP-6124 that resulted in physiological potentiation were consistent with the free drug concentrations in brain that improved memory performance in the ORT. These data suggest that the selective partial agonist EVP-6124 improves memory performance by potentiating the acetylcholine response of α7 nAChRs and support new therapeutic strategies for the treatment of cognitive impairment. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'. Copyright © 2011 Elsevier Ltd. All rights reserved.

Temperature and oxygen-concentration dependence of singlet oxygen production by RuPhen as induced by quasi-continuous excitation.

PubMed

Varchola, Jaroslav; Huntosova, Veronika; Jancura, Daniel; Wagnières, Georges; Miskovsky, Pavol; Bánó, Gregor

2014-12-01

Assessment of partial pressure of oxygen (pO2) by luminescence lifetime measurements of ruthenium coordination complexes has been studied intensively during the last few decades. RuPhen (dichlorotris(1,10-phenanthroline) ruthenium(ii) hydrate) is a water soluble molecule that has been tested previously for in vivo pO2 detection. In this work we intended to shed light on the production of singlet oxygen by RuPhen. The quantum yield of singlet oxygen production by RuPhen dissolved in 0.9% aqueous NaCl solution (pH = 6) was measured at physiological temperatures (285-310 K) and various concentrations of molecular oxygen. In order to minimize the bleaching of RuPhen, the samples were excited with low power (<2 mW) laser pulses (20 μs long), created by pulsing a cw laser beam with an acousto-optical modulator. We show that, whereas the RuPhen phosphorescence lifetime decreases rapidly with an increase of temperature (keeping the oxygenation level constant), the quantum yield of singlet oxygen production by RuPhen is almost identical in the temperature range of 285-310 K. For air-saturated conditions at 310 K the measured quantum yield is about 0.25. The depopulation rate constants of the RuPhen (3)MLCT (metal-to-ligand charge-transfer) state are determined in the absence and in the presence of oxygen. We determined that the excitation energy for the RuPhen (3)MLCT→d-d transition is 49 kJ mol(-1) in the 0.9% NaCl solution (pH = 6).

Hypoxia by degrees: Establishing definitions for a changing ocean

NASA Astrophysics Data System (ADS)

Hofmann, A. F.; Peltzer, E. T.; Walz, P. M.; Brewer, P. G.

2011-12-01

The marked increase in occurrences of low oxygen events on continental shelves coupled with observed expansion of low oxygen regions of the ocean has drawn significant scientific and public attention. With this has come the need for the establishment of better definitions for widely used terms such as "hypoxia" and "dead zones". Ocean chemists and physicists use concentration units such as μmolO2/kg for reporting since these units are independent of temperature, salinity and pressure and are required for mass balances and for numerical models of ocean transport. Much of the reporting of dead zone occurrences is in volumetric concentration units of mlO 2/l or mgO 2/l for historical reasons. And direct measurements of the physiological state of marine animals require reporting of the partial pressure of oxygen (pO 2) in matm or kPa since this provides the thermodynamic driving force for molecular transfer through tissue. This necessarily incorporates temperature and salinity terms and thus accommodates changes driven by climate warming and the influence of the very large temperature range around the world where oxygen limiting values are reported. Here we examine the various definitions used and boundaries set and place them within a common framework. We examine the large scale ocean pO 2 fields required for pairing with pCO 2 data for examination of the combined impacts of ocean acidification and global warming. The term "dead zones", which recently has received considerable attention in both the scientific literature and the press, usually describes shallow, coastal regions of low oxygen caused either by coastal eutrophication and organic matter decomposition or by upwelling of low oxygen waters. While we make clear that bathyal low oxygen waters should not be confused with shallow-water "dead zones", as deep water species are well adapted, we show that those waters represent a global vast reservoir of low oxygen water which can readily be entrained in upwelling waters and contribute to coastal hypoxia around the world and may be characterized identically. We examine the potential for expansion of those water masses onto continental shelves worldwide, thereby crossing limits set for many not adapted species.

Noninvasive, near infrared spectroscopic-measured muscle pH and PO2 indicate tissue perfusion for cardiac surgical patients undergoing cardiopulmonary bypass

NASA Technical Reports Server (NTRS)

Soller, Babs R.; Idwasi, Patrick O.; Balaguer, Jorge; Levin, Steven; Simsir, Sinan A.; Vander Salm, Thomas J.; Collette, Helen; Heard, Stephen O.

2003-01-01

OBJECTIVE: To determine whether near infrared spectroscopic measurement of tissue pH and Po2 has sufficient accuracy to assess variation in tissue perfusion resulting from changes in blood pressure and metabolic demand during cardiopulmonary bypass. DESIGN: Prospective clinical study. SETTING: Academic medical center. SUBJECTS: Eighteen elective cardiac surgical patients. INTERVENTION: Cardiac surgery under cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: A near infrared spectroscopic fiber optic probe was placed over the hypothenar eminence. Reference Po2 and pH sensors were inserted in the abductor digiti minimi (V). Data were collected every 30 secs during surgery and for 6 hrs following cardiopulmonary bypass. Calibration equations developed from one third of the data were used with the remaining data to investigate sensitivity of the near infrared spectroscopic measurement to physiologic changes resulting from cardiopulmonary bypass. Near infrared spectroscopic and reference pH and Po2 measurements were compared for each subject using standard error of prediction. Near infrared spectroscopic pH and Po2 at baseline were compared with values during cardiopulmonary bypass just before rewarming commenced (hypotensive, hypothermic), after rewarming (hypotensive, normothermic) just before discontinuation of cardiopulmonary bypass, and at 6 hrs following cardiopulmonary bypass (normotensive, normothermic) using mixed-model analysis of variance. Near infrared spectroscopic pH and Po2 were well correlated with the invasive measurement of pH (R2 =.84) and Po2 (R 2 =.66) with an average standard error of prediction of 0.022 +/- 0.008 pH units and 6 +/- 3 mm Hg, respectively. The average difference between the invasive and near infrared spectroscopic measurement was near zero for both the pH and Po2 measurements. Near infrared spectroscopic Po2 significantly decreased 50% on initiation of cardiopulmonary bypass and remained depressed throughout the bypass and monitored intensive care period. Near infrared spectroscopic pH decreased significantly during cardiopulmonary bypass, decreased significantly during rewarming, and remained depressed 6 hrs after cardiopulmonary bypass. Diabetic patients responded differently than nondiabetic subjects to cardiopulmonary bypass, with lower muscle pH values (p =.02). CONCLUSIONS: Near infrared spectroscopic-measured muscle pH and Po2 are sensitive to changes in tissue perfusion during cardiopulmonary bypass.

Low-temperature sintering and electrical properties of strontium- and magnesium-doped lanthanum gallate with V2O5 additive

NASA Astrophysics Data System (ADS)

Ha, Sang Bu; Cho, Yoon Ho; Ji, Ho-Il; Lee, Jong-Ho; Kang, Yun Chan; Lee, Jong-Heun

2011-03-01

The effects of a V2O5 additive on the low-temperature sintering and ionic conductivity of strontium- and magnesium-doped lanthanum gallate (LSGM: La0.8Sr0.2Ga0.8Mg0.2O2.8) are studied. The LSGM powders prepared by the glycine nitrate method are mixed with 0.5-2 at.% of VO5/2 and then sintered at 1100-1400 °C in air for 4 h. The apparent density and phase purity of the LSGM specimens are increased with increasing sintering temperature and VO5/2 concentration due to the enhanced sintering and mass transfer via the intergranular liquid phase. The 1 at.% VO5/2-doped LSGM specimen sintered at 1300 °C exhibits a high oxide ion conductivity of ∼0.027 S cm-1 at 700 °C over a wide range of oxygen partial pressure (PO2 =10-27 - 1 atm), thereby demonstrating its potential as a useful electrolyte for anode-supported solid oxide fuel cells (SOFCs) without the requirement for any buffer layer between the electrolyte and anode.

Measurement of oxygen tension in the ischemic myocardium using encased polargraphic oxygen electrodes.

PubMed

Barrett, J A; Lynch, V D; Balkon, J; Wolf, P S

1986-06-01

The ability to continuously monitor the delicate balance between blood flow and oxygen consumption would be a great asset in the study of myocardial ischemia. The present study was performed, in anesthetized dogs, to validate the use of encased polargraphic oxygen electrodes in the study of myocardial ischemia. Polargraphic oxygen electrodes were placed in the area to be rendered ischemic at fixed tissue depths of 3 mm (epicardium) and 9 mm (endocardium). Endocardial and epicardial oxygen tensions as well as the ratio of endocardial to epicardial oxygen tension and left circumflex coronary flow were monitored. Ischemia was induced by decreasing left circumflex coronary flow by 50%. Upon completion of a 20-min poststenotic period, endocardial pO2, endocardial/epicardial ratio, and coronary flow were significantly decreased (59 +/- 7, 52 +/- 7, and 55 +/- 4%, respectively) whereas epicardial pO2 was slightly decreased. Nitroglycerin (10 micrograms/kg, i.v.) markedly increased endocardial pO2 and endocardial/epicardial ratio above poststenotic control (13 +/- 5 mmHg and 64 +/- 10%, respectively) whereas epicardial pO2 was not significantly decreased. The increases in endocardial pO2 occurred at a point where coronary flow and mean arterial pressure were not significantly changed. Conversely, dipyridamole (125 micrograms/kg, i.v.) significantly increased coronary flow (26 +/- 2 ml/min/100 g) although it did not appreciably alter endocardial or epicardial pO2. It is concluded that encased polargraphic oxygen electrodes provide a quantitative method for determination of oxygen tension in the ischemic myocardium.

A new device for administration of continuous positive airway pressure in preterm infants: comparison with a standard nasal CPAP continuous positive airway pressure system.

PubMed

Trevisanuto, Daniele; Grazzina, Nicoletta; Doglioni, Nicoletta; Ferrarese, Paola; Marzari, Francesco; Zanardo, Vincenzo

2005-06-01

We compared the effectiveness of a new continuous positive airway pressure (CPAP) device (neonatal helmet CPAP) with a conventional nasal CPAP system in preterm neonates needing continuous distending pressure. Randomized, physiological, cross-over study in a tertiary referral, neonatal intensive care unit in a university teaching hospital. Twenty very low birth weight infants with a postnatal age greater than 24 h who were receiving nasal CPAP for apnea and/or mild respiratory distress were enrolled. CPAP delivered by neonatal helmet CPAP and nasal CPAP in random order for two subsequent 90-min periods. Were continuously measured the Neonatal Infant Pain Scale (NIPS) score, oxygen requirements, respiratory rate, heart rate, oxygen saturation, transcutaneous PO(2) (tcPO(2)) and PCO(2) (tcPCO(2)), blood pressure, and desaturations. NIPS scores were significantly lower when the infants were on the neonatal helmet CPAP than when they were on nasal CPAP (0.26+/-0.07 vs. 0.63+/-0.12). The other studied parameters did not differ between the two CPAP modes. The number of desaturations was reduced during the neonatal helmet CPAP treatment (18 vs. 32), although this difference was not significant. In this short-term physiological study the neonatal helmet CPAP appears to be as good as the golden standard for managing preterm infants needing continuous distending pressure, with enhanced tolerability. Further evaluation in a randomized clinical trial is needed to confirm these findings.

Oxygen partial pressure effects on the RF sputtered p-type NiO hydrogen gas sensors

NASA Astrophysics Data System (ADS)

Turgut, Erdal; Çoban, Ömer; Sarıtaş, Sevda; Tüzemen, Sebahattin; Yıldırım, Muhammet; Gür, Emre

2018-03-01

NiO thin films were grown by Radio Frequency (RF) Magnetron Sputtering method under different oxygen partial pressures, which are 0.6 mTorr, 1.3 mTorr and 2.0 mTorr. The effects of oxygen partial pressures on the thin films were analyzed through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Hall measurements. The change in the surface morphology of the thin films has been observed with the SEM and AFM measurements. While nano-pyramids have been obtained on the thin film grown at the lowest oxygen partial pressure, the spherical granules lower than 60 nm in size has been observed for the samples grown at higher oxygen partial pressures. The shift in the dominant XRD peak is realized to the lower two theta angle with increasing the oxygen partial pressures. XPS measurements showed that the Ni2p peak involves satellite peaks and two oxidation states of Ni, Ni2+ and Ni3+, have been existed together with the corresponding splitting in O1s spectrum. P-type conductivity of the grown NiO thin films are confirmed by the Hall measurements with concentrations on the order of 1013 holes/cm-3. Gas sensor measurements revealed minimum of 10% response to the 10 ppm H2 level. Enhanced responsivity of the gas sensor devices of NiO thin films is shown as the oxygen partial pressure increases.

Stem hypertrophic lenticels and secondary aerenchyma enable oxygen transport to roots of soybean in flooded soil.

PubMed

Shimamura, Satoshi; Yamamoto, Ryo; Nakamura, Takuji; Shimada, Shinji; Komatsu, Setsuko

2010-08-01

Aerenchyma provides a low-resistance O(2) transport pathway that enhances plant survival during soil flooding. When in flooded soil, soybean produces aerenchyma and hypertrophic stem lenticels. The aims of this study were to investigate O(2) dynamics in stem aerenchyma and evaluate O(2) supply via stem lenticels to the roots of soybean during soil flooding. Oxygen dynamics in aerenchymatous stems were investigated using Clark-type O(2) microelectrodes, and O(2) transport to roots was evaluated using stable-isotope (18)O(2) as a tracer, for plants with shoots in air and roots in flooded sand or soil. Short-term experiments also assessed venting of CO(2) via the stem lenticels. The radial distribution of the O(2) partial pressure (pO(2)) was stable at 17 kPa in the stem aerenchyma 15 mm below the water level, but rapidly declined to 8 kPa at 200-300 microm inside the stele. Complete submergence of the hypertrophic lenticels at the stem base, with the remainder of the shoot still in air, resulted in gradual declines in pO(2) in stem aerenchyma from 17.5 to 7.6 kPa at 13 mm below the water level, and from 14.7 to 6.1 kPa at 51 mm below the water level. Subsequently, re-exposure of the lenticels to air caused pO(2) to increase again to 14-17 kPa at both positions within 10 min. After introducing (18)O(2) gas via the stem lenticels, significant (18)O(2) enrichment in water extracted from roots after 3 h was confirmed, suggesting that transported O(2) sustained root respiration. In contrast, slight (18)O(2) enrichment was detected 3 h after treatment of stems that lacked aerenchyma and lenticels. Moreover, aerenchyma accelerated venting of CO(2) from submerged tissues to the atmosphere. Hypertrophic lenticels on the stem of soybean, just above the water surface, are entry points for O(2), and these connect to aerenchyma and enable O(2) transport into roots in flooded soil. Stems that develop aerenchyma thus serve as a 'snorkel' that enables O(2) movement from air to the submerged roots.

Oxygen distribution in tumors: a qualitative analysis and modeling study providing a novel Monte Carlo approach.

PubMed

Lagerlöf, Jakob H; Kindblom, Jon; Bernhardt, Peter

2014-09-01

To construct a Monte Carlo (MC)-based simulation model for analyzing the dependence of tumor oxygen distribution on different variables related to tumor vasculature [blood velocity, vessel-to-vessel proximity (vessel proximity), and inflowing oxygen partial pressure (pO2)]. A voxel-based tissue model containing parallel capillaries with square cross-sections (sides of 10 μm) was constructed. Green's function was used for diffusion calculations and Michaelis-Menten's kinetics to manage oxygen consumption. The model was tuned to approximately reproduce the oxygenational status of a renal carcinoma; the depth oxygenation curves (DOC) were fitted with an analytical expression to facilitate rapid MC simulations of tumor oxygen distribution. DOCs were simulated with three variables at three settings each (blood velocity, vessel proximity, and inflowing pO2), which resulted in 27 combinations of conditions. To create a model that simulated variable oxygen distributions, the oxygen tension at a specific point was randomly sampled with trilinear interpolation in the dataset from the first simulation. Six correlations between blood velocity, vessel proximity, and inflowing pO2 were hypothesized. Variable models with correlated parameters were compared to each other and to a nonvariable, DOC-based model to evaluate the differences in simulated oxygen distributions and tumor radiosensitivities for different tumor sizes. For tumors with radii ranging from 5 to 30 mm, the nonvariable DOC model tended to generate normal or log-normal oxygen distributions, with a cut-off at zero. The pO2 distributions simulated with the six-variable DOC models were quite different from the distributions generated with the nonvariable DOC model; in the former case the variable models simulated oxygen distributions that were more similar to in vivo results found in the literature. For larger tumors, the oxygen distributions became truncated in the lower end, due to anoxia, but smaller tumors showed undisturbed oxygen distributions. The six different models with correlated parameters generated three classes of oxygen distributions. The first was a hypothetical, negative covariance between vessel proximity and pO2 (VPO-C scenario); the second was a hypothetical positive covariance between vessel proximity and pO2 (VPO+C scenario); and the third was the hypothesis of no correlation between vessel proximity and pO2 (UP scenario). The VPO-C scenario produced a distinctly different oxygen distribution than the two other scenarios. The shape of the VPO-C scenario was similar to that of the nonvariable DOC model, and the larger the tumor, the greater the similarity between the two models. For all simulations, the mean oxygen tension decreased and the hypoxic fraction increased with tumor size. The absorbed dose required for definitive tumor control was highest for the VPO+C scenario, followed by the UP and VPO-C scenarios. A novel MC algorithm was presented which simulated oxygen distributions and radiation response for various biological parameter values. The analysis showed that the VPO-C scenario generated a clearly different oxygen distribution from the VPO+C scenario; the former exhibited a lower hypoxic fraction and higher radiosensitivity. In future studies, this modeling approach might be valuable for qualitative analyses of factors that affect oxygen distribution as well as analyses of specific experimental and clinical situations.

Monoclinic structure of hydroxylpyromorphite Pb10(PO4)6(OH)2 - hydroxylmimetite Pb10(AsO4)6(OH)2 solid solution series

NASA Astrophysics Data System (ADS)

Giera, Alicja; Manecki, Maciej; Borkiewicz, Olaf; Zelek, Sylwia; Rakovan, John; Bajda, Tomasz; Marchlewski, Tomasz

2016-04-01

Seven samples of hydroxyl analogues of pyromorphite-mimetite solid solutions series were synthesized from aqueous solutions at 80° C in a computer-controlled chemistate: 200 mL aqueous solutions of 0.05M Pb(NO3)2 and 0.03M KH2AsO4 and/or KH2PO4 were dosed with a 0.25 mL/min rate to a glass beaker, which initially contained 100 mL of distilled water. Constant pH of 8 was maintained using 2M KOH. The syntheses yielded homogeneous fine-grained white precipitates composition of which was close to theoretical Pb10[(PO4)6-x(AsO4)x](OH)2, where x = 0, 1, 2, 3, 4, 5, 6. High-resolution powder X-ray diffraction data were obtained in transmission geometry at the beamline 11-BM at the Advanced Photon Source (Argonne National Laboratory in Illinois, USA). The structure Rietveld refinements based on starting parameters of either hexagonal hydroxylpyromorphite or monoclinic mimetite-M were performed using GSAS+EXPGUI software. Apatite usually crystallizes in the hexagonal crystal system with the space group P63/m. For the first time, however, the lowering of the hexagonal to monoclinic crystal symmetry was observed in the hydroxyl variety of pyromorphite-mimetite solid solution series. This is indicated by better fitting of the modeled monoclinic structure to the experimental data. The same is not the case for analogous calcium hydroxylapatite series Ca5(PO4)3OH - Ca5(AsO4)3OH (Lee et al. 2009). Systematical linear increase of unit cell parameters is observed with As substitution from a=9.88, b=19.75, and c=7.43 for Pb10(PO4)6(OH)2 to a=10.23, b=20.32, and c=7.51 for Pb10(AsO4)6(OH)2. A strong pseudohexagonal character (γ ≈ 120° and b ≈ 2a) of the analyzed monoclinic phases was established. This work is partially funded by AGH research grant no 11.11.140.319 and partially by Polish NCN grant No 2011/01/M/ST10/06999. Lee Y.J., Stephens P.W., Tang Y., Li W., Philips B.L., Parise J.B., Reeder R.J., 2009. Arsenate substitution in hydroxylapatite: Structural characterization of the Ca5(PxAs1-xO4)3OH solid solution. American Mineralogist, 94, 666-675.

Photosynthetic induction and its diffusional, carboxylation and electron transport processes as affected by CO2 partial pressure, temperature, air humidity and blue irradiance.

PubMed

Kaiser, Elias; Kromdijk, Johannes; Harbinson, Jeremy; Heuvelink, Ep; Marcelis, Leo F M

2017-01-01

Plants depend on photosynthesis for growth. In nature, factors such as temperature, humidity, CO 2 partial pressure, and spectrum and intensity of irradiance often fluctuate. Whereas irradiance intensity is most influential and has been studied in detail, understanding of interactions with other factors is lacking. We tested how photosynthetic induction after dark-light transitions was affected by CO 2 partial pressure (20, 40, 80 Pa), leaf temperatures (15·5, 22·8, 30·5 °C), leaf-to-air vapour pressure deficits (VPD leaf-air ; 0·5, 0·8, 1·6, 2·3 kPa) and blue irradiance (0-20 %) in tomato leaves (Solanum lycopersicum). Rates of photosynthetic induction strongly increased with CO 2 partial pressure, due to increased apparent Rubisco activation rates and reduced diffusional limitations. High leaf temperature produced slightly higher induction rates, and increased intrinsic water use efficiency and diffusional limitation. High VPD leaf-air slowed down induction rates and apparent Rubisco activation and (at 2·3 kPa) induced damped stomatal oscillations. Blue irradiance had no effect. Slower apparent Rubisco activation in elevated VPD leaf-air may be explained by low leaf internal CO 2 partial pressure at the beginning of induction. The environmental factors CO 2 partial pressure, temperature and VPD leaf-air had significant impacts on rates of photosynthetic induction, as well as on underlying diffusional, carboxylation and electron transport processes. Furthermore, maximizing Rubisco activation rates would increase photosynthesis by at most 6-8 % in ambient CO 2 partial pressure (across temperatures and humidities), while maximizing rates of stomatal opening would increase photosynthesis by at most 1-3 %. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Atmospheric Oxygen Concentrations for the Past 350 Myr Modeled from the δ13C of C3 Land Plants

NASA Astrophysics Data System (ADS)

Nordt, L.; Breecker, D.

2016-12-01

Numerous studies have focused on the systematic collection of long-term d13C records from marine sediments, but no such isotopic compilation exists for C3 land plants. Consequently, we gathered a meta-data base of 8003 plant-derived δ13C values (ISOORG) from various carbon sources binned into 5 myr time steps. The results of this investigation were reported in a recent publication showing that most δ13C sources co-vary with ten CIEs during the last 400 myr. For this paper we culled ISOORG to produce ISOORG16-H that contains 7025 plant-derived δ13C values from paleo-moist environments to reflect secular controls on the δ13C of C3 plants. We then constructed atmospheric pO2 curves for the past 350 myr using prior experimental work showing a direct relationship between the Δ13C of C3 plants and pO2 concentration. Periods of hyperoxia (25-30% pO2) were identified from 300-250, 225-190, and 110-105 myr, and intervals of hypoxia (10-15% pO2) from 350-345, 245-230, and 185-115 myr. During the last 150 myr, pO2 stabilized at 17-24% except for a notable positive excursion from 110-105 myr. Hyperoxia, apparently from widespread carbon burial, supports the notion of insect gigantism during the Late Paleozoic. Hypoxia during the early Triassic correlates with the coal gap following the collapse of Paleozoic ecosystems. Rising pO2 in the late Triassic seems to reflect renewed carbon burial from reorganization of Mesozoic ecosystems. The middle Mesozoic is characterized by low pO2 during an intense greenhouse interval, with ambient conditions ensuing thereafter possibly linked to carbon burial from the radiation of angiosperms. pO2 concentrations >14% suggest wildfires persisted through the study interval except possibly at 160 and 140 myr. Intervals of low pO2 concentration were likely accompanied by lower atmospheric pressure and higher temperatures, particularly from 245-230 myr and 180-120 myr. Our O2 reconstructions conform with GEOCARBSULF, but not with proxy predictions from charcoal abundance or the δ13C of amber where the former overestimates and the latter underestimates pO2, respectively, compared to GEOCARBSULF. Results of our new proxy are encouraging, but further experimental work is needed to better understand the dynamics of pO2 and pCO2 on the Δ13C of C3 plants for application to paleobarometers.

KH2PO4 single crystals activated with the Ti4+ ions in the form of TiO2-x × nH2O nanoparticles: Structural peculiarities, point defects, and dielectric properties

NASA Astrophysics Data System (ADS)

Kuz'micheva, Galina M.; Timaeva, Olesya I.; Kaurova, Irina A.; Svetogorov, Roman D.; Mühlbauer, Martin J.

2018-03-01

Potassium dihydrogen phosphate KH2PO4 (KDP) single crystals activated with Ti4+ ions in the form of TiO2-x × nH2O nanoparticles in the η-phase, synthesized by the sulfate method using TiOSO4 × xH2SO4 × yH2O, have been first grown by the temperature lowering method and cut from pyramidal (P) and prismatic (Pr) growth sectors. The first-performed neutron powder diffraction investigation of P and Pr samples cut from the KDP:Ti4+ crystal allowed us to reveal vacancies in the K and H sites for both samples, their number being larger in the Pr structure compared to the P one. Taking into account the deficiency of the K and H sites, full occupation of the O site, presence of Ti4+ ions in the structure, and the electroneutrality condition, a partial substitution of (PO4)3- anion by the (SO4)2- one, larger for the Pr sample, was observed. The real compositions of P and Pr samples, correlated with the cation-anion internuclear distances, were refined. The dielectric permittivity of the Pr sample was significantly lower than that of the P one; it decreases with decreasing K-O, P-O, and O...H distances and increasing deficiency of the K and H sites.

Magnesium taurate prevents cataractogenesis via restoration of lenticular oxidative damage and ATPase function in cadmium chloride-induced hypertensive experimental animals.

PubMed

Choudhary, Rajesh; Bodakhe, Surendra H

2016-12-01

Previously we found that hypertension potentiates the risk the cataractogenesis. In the present study, we investigated the protective effects of magnesium taurate (MgT) on hypertension and associated lenticular damages against cadmium chloride (CdCl 2 )-induced hypertensive animals. Male Sprague-Dawley albino rats (150-180g) were assigned to five experimental groups (n=6). Among the five groups, normal group received 0.3% carboxymethyl cellulose (10ml/kg/day, p.o.). Hypertension control group received CdCl 2 (0.5mg/kg/day, i.p.). Tests and standard groups received MgT (3 and 6mg/kg/day, p.o.) and amlodipine (3mg/kg/day, p.o.) concurrently with CdCl 2 respectively , for six consecutive weeks. Blood pressure, heart rate, and eyes were examined biweekly, and pathophysiological parameters in serum and eye lenses were evaluated after six weeks of the experimental protocol. The chronic administration of MgT concurrently with CdCl 2 significantly restored the blood pressure, serum and lens antioxidants (CAT, SOD, GPx, and GSH), MDA level, and ions (Na + , K + , and Ca 2+ ). Additionally, MgT treatment led to significant increase in the lens proteins (total and soluble), Ca 2+ ATPase, and Na + K + ATPase activity as compared to hypertension control group. Ophthalmoscope observations indicated that MgT treatments delayed the progression of cataract against the hypertensive state. The study shows that MgT prevents the progression of cataractogenesis via restoration of blood pressure, lenticular oxidative damages, and lens ATPase functions in the hypertensive state. The results suggest that MgT supplement may play a beneficial role to manage hypertension and associated cataractogenesis. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Synthesis, characterization, vibrational spectroscopy, and factor group analysis of partially metal-doped phosphate materials.

PubMed

Sronsri, Chuchai; Boonchom, Banjong

2018-04-05

A simple precipitating method was used to synthesize effectively a partially metal-doped phosphate hydrate (Mn 0.9 Mg 0.1 HPO 4 ·3H 2 O), whereas the thermal decomposition process of the above hydrate precursor was used to obtain Mn 1.8 Mg 0.2 P 2 O 7 and LiMn 0.9 Mg 0.1 PO 4 compounds under different conditions. To separate the overlapping thermal decomposition peak, a deconvolution technique was used, and the separated peak was applied to calculate the water content. The factor group splitting analysis was used to exemplify their vibrational spectra obtained from normal vibrations of HPO 4 2- , H 2 O, P 2 O 7 4- and PO 4 3- functional groups. Further, the deconvoluted bending mode of water was clearly observed. Mn 0.9 Mg 0.1 HPO 4 ·3H 2 O was observed in the orthorhombic crystal system with the space group of Pbca (D 2h 15 ). The formula units per unit cell were found to be eight (Z = 8), and the site symmetric type of HPO 4 2- was observed as C s . For the HPO 4 2- unit, the correlation filed splitting analysis of type C 3v  - C s  - D 2h 15 was calculated and had 96 internal modes, whereas H 2 O in the above hydrate was symbolized as C 2v  - C s  - D 2h 15 and had 24 modes. The symbol C 2v  - C s  - C 2h 3 was used for the correlation filed splitting analysis of P 2 O 7 4- in Mn 1.8 Mg 0.2 P 2 O 7 (monoclinic, C2/m (C 2h 3 ), Z = 2, and 42 modes). Finally, the symbol T d  - C s  - D 2h 16 was used for the correlation filed splitting analysis of PO 4 3- in LiMn 0.9 Mg 0.1 PO 4 (orthorhombic, Pnma (D 2h 16 ), Z = 4, and 36 modes). Copyright © 2018 Elsevier B.V. All rights reserved.

Antinociceptive activity of Hypericum caprifoliatum and Hypericum polyanthemum (Guttiferae).

PubMed

Viana, A F; Heckler, A P; Fenner, R; Rates, S M K

2003-05-01

The aim of the present study was to assess the analgesic activity of the aerial parts of two Hypericum species native to Southern Brazil, H. caprifoliatum and H. polyanthemum. The antinociceptive effect of the H. polyanthemum cyclohexane extract (POL; 180 mg/kg) and of the H. caprifoliatum methanol (MET) and cyclohexane (CH) extracts (90 mg/kg) was evaluated in the hot-plate (ip and po) and writhing (po) tests using male Swiss CF1 mice weighing 22-27 g (N = 10 per group). All extracts displayed antinociceptive effects in the hot-plate test (MET ip = 48%, MET po = 39%, CH ip = 27%, CH po = 50%, POL ip = 74%, and POL po = 49% compared to control). Pretreatment with naloxone (2.5 mg/kg, sc) abolished the effects of CH and POL, and partially prevented the analgesia induced by MET administered by the ip (but not by the po) route. POL and CH (po) significantly reduced the number of writhes induced by acetic acid, while MET was ineffective in this regard. We conclude that the antinociceptive effects of the H. caprifoliatum (CH) and H. polyanthemum (POL) hexane extracts seem to be mediated by the opioid system. Moreover, the antinociceptive activity of the H. caprifoliatum MET extract seems to depend on at least two chemical substances (or groups of substances) with distinct pharmacokinetic profiles and mechanisms of action. Only the naloxone-insensitive component of MET activity showed good bioavailability following oral administration.

In Situ High Temperature High Pressure MAS NMR Study on the Crystallization of AlPO 4 -5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Zhenchao; Xu, Suochang; Hu, Mary Y.

2016-01-28

A damped oscillating crystallization process of AlPO4-5 at the presence of small amount of water is demonstrated by in situ high temperature high pressure multinuclear MAS NMR. Crystalline AlPO4-5 is formed from an intermediate semicrystalline phase via continuous rearrangement of the local structure of amorphous precursor gel. Activated water catalyzes the rearrangement via repeatedly hydrolysis and condensation reaction. Strong interactions between organic template and inorganic species facilitate the ordered rearrangement. During the crystallization process, excess water, phosphate, and aluminums are expelled from the precursor. The oscillating crystallization reflects mass transportation between the solid and liquid phase during the crystallization process.more » This crystallization process is also applicable to AlPO4-5 crystallized in the presence of a relatively large amount of water.« less

Pharmacokinetics of flunixin meglumine in mature swine after intravenous, intramuscular and oral administration

PubMed Central

2013-01-01

Background The purpose of this study was to determine intravenous (IV), intramuscular (IM) and oral (PO) FM PK in mature swine. Appropriate pain management for lameness in swine is a critical control point for veterinarians and producers, but science-based guidance on optimal housing, management and treatment of lameness is deficient. Six mature swine (121–168 kg) were administered an IV, IM, or PO dose of flunixin meglumine at a target dose of 2.2 mg/kg in a cross-over design with a 10 day washout period between treatments. Plasma samples collected up to 48 hours post-administration were analyzed by high pressure liquid chromatography and mass spectrometry (HPLC-MS) followed by non-compartmental pharmacokinetic analysis. Results No adverse effects were observed with flunixin meglumine administration for all routes. Flunixin meglumine was administered at an actual mean dose of 2.21 mg/kg (range: 2.05-2.48 mg/kg) IV, IM and PO. A mean peak plasma concentration (CMAX) for IM and PO administration was 3748 ng/ml (range: 2749–6004 ng/ml) and 946 ng/ml (range: 554–1593 ng/ml), respectively. TMAX was recorded at 1.00 hour (range: 0.50-2.00 hours) and 0.61 hours (range: 0.17-2.00 hours) after PO and IM administration. Half-life (T ½ λz) for IV, IM and PO administration was 6.29 hours (range: 4.84-8.34 hours), 7.49 hours (range: 5.55-12.98 hours) and 7.08 hours (range: 5.29-9.15 hours) respectively. In comparison, bioavailability (F) for PO administration was 22% (range: 11-44%) compared to IM F at 76% (range: 54-92%). Conclusions The results of the present study suggest that FM oral administration is not the most effective administration route for mature swine when compared to IV and IM. Lower F and Cmax of PO-FM in comparison to IM-FM suggest that PO-FM is less likely to be an effective therapeutic administration route. PMID:23941181

Activation of methane by transition metal-substituted aluminophosphate molecular sieves

DOEpatents

Iton, Lennox E.; Maroni, Victor A.

1991-01-01

Aluminophosphate molecular sieves substituted with cobalt, manganese or iron and having the AlPO.sub.4 -34 or AlPO.sub.4 -5, or related AlPO.sub.4 structure activate methane starting at approximately 350.degree. C. Between 400.degree. and 500.degree. C. and at methane pressures .ltoreq.1 atmosphere the rate of methane conversion increases steadily with typical conversion efficiencies at 500.degree. C. approaching 50% and selectivity to the production of C.sub.2+ hydrocarbons approaching 100%. The activation mechanism is based on reduction of the transition metal(III) form of the molecular sieve to the transition metal(II) form with accompanying oxidative dehydrogenation of the methane. Reoxidation of the - transition metal(II) form to the transition metal(III) form can be done either chemically (e.g., using O.sub.2) or electrochemically.

A novel technique of Roux-en-Y gastric bypass reversal for postprandial hyperinsulinemic hypoglycaemia: A case report.

PubMed

Qvigstad, E; Gulseth, H L; Risstad, H; le Roux, C W; Berg, T J; Mala, T; Kristinsson, J A

2016-01-01

We describe an evaluation of the effects of partial Roux-en-Y gastric bypass (RYGB) reversal on postprandial hyperinsulinaemic hypoglycaemia, insulin and GLP-1 levels. A 37 year old man was admitted with neuroglycopenia (plasma-glucose 1.6mmol/l) 18 months after RYGB, with normal 72h fasting test and abdominal CT. Despite dietary modifications and medical treatment, the hypoglycaemic episodes escalated in frequency. Feeding by a gastrostomy tube positioned in the gastric remnant did not prevent severe episodes of hypoglycaemia. A modified reversal of the RYGB was performed. Mixed meal tests were done perorally (PO), through the gastrostomy tube 1 (GT1), 4 weeks (GT2) after placement and 4 weeks after reversal (POr), with assessment of glucose, insulin and GLP-1 levels. Plasma-glucose increased to a maximum of 9.6, 5.4, 6.5 and 5.8mmol/l at the PO, GT1, GT2 and POr tests respectively. The corresponding insulin levels were 2939, 731, 725 and 463pmol/l. A decrease of plasma-glucose followed: 2.2, 3.0, 3.9 and 2.9mmol/l respectively and insulin levels were suppressed at 150min: 45, 22, 21 and 14pmol/l, respectively. GLP-1 levels increased in the PO test (60min: 122pmol/l, 21 fold of basal), but was attenuated in the two latter tests (12-23pmol/l at 60min). Reduction of plasma-glucose, insulin and GLP-1 excursions and symptoms were seen after gastric tube placement and partial RYGB reversal. This attenuation of GLP-1 response to feeding could reflect an adaptation to nutrients. Copyright © 2016. Published by Elsevier Ltd.

Beneficial Effects of Galectin-3 Blockade in Vascular and Aortic Valve Alterations in an Experimental Pressure Overload Model

PubMed Central

Ibarrola, Jaime; Martínez-Martínez, Ernesto; Sádaba, J. Rafael; Arrieta, Vanessa; García-Peña, Amaia; Álvarez, Virginia; Fernández-Celis, Amaya; Gainza, Alicia; Rossignol, Patrick; Cachofeiro Ramos, Victoria; López-Andrés, Natalia

2017-01-01

Galectin-3 (Gal-3) is involved in cardiovascular fibrosis and aortic valve (AV) calcification. We hypothesized that Gal-3 pharmacological inhibition with modified citrus pectin (MCP) could reduce aortic and AV remodeling in normotensive rats with pressure overload (PO). Six weeks after aortic constriction, vascular Gal-3 expression was up-regulated in male Wistar rats. Gal-3 overexpression was accompanied by an increase in the aortic media layer thickness, enhanced total collagen, and augmented expression of fibrotic mediators. Further, vascular inflammatory markers as well as inflammatory cells content were greater in aorta from PO rats. MCP treatment (100 mg/kg/day) prevented the increase in Gal-3, media thickness, fibrosis, and inflammation in the aorta of PO rats. Gal-3 levels were higher in AVs from PO rats. This paralleled enhanced AV fibrosis, inflammation, as well as greater expression of calcification markers. MCP treatment prevented the increase in Gal-3 as well as fibrosis, inflammation, and calcification in AVs. Overall, Gal-3 is overexpressed in aorta and AVs from PO rats. Gal-3 pharmacological inhibition blocks aortic and AV remodeling in experimental PO. Gal-3 could be a new therapeutic approach to delay the progression and the development of aortic remodeling and AV calcification in PO. PMID:28758988

Detailing the relation between renal T2* and renal tissue pO2 using an integrated approach of parametric magnetic resonance imaging and invasive physiological measurements.

PubMed

Pohlmann, Andreas; Arakelyan, Karen; Hentschel, Jan; Cantow, Kathleen; Flemming, Bert; Ladwig, Mechthild; Waiczies, Sonia; Seeliger, Erdmann; Niendorf, Thoralf

2014-08-01

This study was designed to detail the relation between renal T2* and renal tissue pO2 using an integrated approach that combines parametric magnetic resonance imaging (MRI) and quantitative physiological measurements (MR-PHYSIOL). Experiments were performed in 21 male Wistar rats. In vivo modulation of renal hemodynamics and oxygenation was achieved by brief periods of aortic occlusion, hypoxia, and hyperoxia. Renal perfusion pressure (RPP), renal blood flow (RBF), local cortical and medullary tissue pO2, and blood flux were simultaneously recorded together with T2*, T2 mapping, and magnetic resonance-based kidney size measurements (MR-PHYSIOL). Magnetic resonance imaging was carried out on a 9.4-T small-animal magnetic resonance system. Relative changes in the invasive quantitative parameters were correlated with relative changes in the parameters derived from MRI using Spearman analysis and Pearson analysis. Changes in T2* qualitatively reflected tissue pO2 changes induced by the interventions. T2* versus pO2 Spearman rank correlations were significant for all interventions, yet quantitative translation of T2*/pO2 correlations obtained for one intervention to another intervention proved not appropriate. The closest T2*/pO2 correlation was found for hypoxia and recovery. The interlayer comparison revealed closest T2*/pO2 correlations for the outer medulla and showed that extrapolation of results obtained for one renal layer to other renal layers must be made with due caution. For T2* to RBF relation, significant Spearman correlations were deduced for all renal layers and for all interventions. T2*/RBF correlations for the cortex and outer medulla were even superior to those between T2* and tissue pO2. The closest T2*/RBF correlation occurred during hypoxia and recovery. Close correlations were observed between T2* and kidney size during hypoxia and recovery and for occlusion and recovery. In both cases, kidney size correlated well with renal vascular conductance, as did renal vascular conductance with T2*. Our findings indicate that changes in T2* qualitatively mirror changes in renal tissue pO2 but are also associated with confounding factors including vascular volume fraction and tubular volume fraction. Our results demonstrate that MR-PHYSIOL is instrumental to detail the link between renal tissue pO2 and T2* in vivo. Unravelling the link between regional renal T2* and tissue pO2, including the role of the T2* confounding parameters vascular and tubular volume fraction and oxy-hemoglobin dissociation curve, requires further research. These explorations are essential before the quantitative capabilities of parametric MRI can be translated from experimental research to improved clinical understanding of hemodynamics/oxygenation in kidney disorders.

A Kinase-Independent Function of c-Src Mediates p130Cas Phosphorylation at the Serine-639 Site in Pressure Overloaded Myocardium

PubMed Central

Palanisamy, Arun P.; Suryakumar, Geetha; Panneerselvam, Kavin; Willey, Christopher D.; Kuppuswamy, Dhandapani

2017-01-01

Early work in pressure overloaded (PO) myocardium shows that integrins mediate focal adhesion complex formation by recruiting the adaptor protein p130Cas (Cas) and nonreceptor tyrosine kinase c-Src. To explore c-Src role in Cas-associated changes during PO, we used a feline right ventricular in vivo PO model and a three-dimensional (3D) collagen-embedded adult cardiomyocyte in vitro model that utilizes a Gly-Arg-Gly-Asp-Ser (RGD) peptide for integrin stimulation. Cas showed slow electrophoretic mobility (band-shifting), recruitment to the cytoskeleton, and tyrosine phosphorylation at 165, 249, and 410 sites in both 48 h PO myocardium and 1 h RGD-stimulated cardiomyocytes. Adenoviral mediated expression of kinase inactive (negative) c-Src mutant with intact scaffold domains (KN-Src) in cardiomyocytes did not block the RGD stimulated changes in Cas. Furthermore, expression of KN-Src or kinase active c-Src mutant with intact scaffold function (A-Src) in two-dimensionally (2D) cultured cardiomyocytes was sufficient to cause Cas band-shifting, although tyrosine phosphorylation required A-Src. These data indicate that c-Src’s adaptor function, but not its kinase function, is required for a serine/threonine specific phosphorylation(s) responsible for Cas band-shifting. To explore this possibility, Chinese hamster ovary cells that stably express Cas were infected with either β-gal or KN-Src adenoviruses and used for Cas immunoprecipitation combined with mass spectrometry analysis. In the KN-Src expressing cells, Cas showed phosphorylation at the serine-639 (human numbering) site. A polyclonal antibody raised against phospho-serine-639 detected Cas phosphorylation in 24–48 h PO myocardium. Our studies indicate that c-Src’s adaptor function mediates serine-639 phosphorylation of Cas during integrin activation in PO myocardium. PMID:25976166

Integrated study of first principles calculations and experimental measurements for Li-ionic conductivity in Al-doped solid-state LiGe2(PO4)3 electrolyte

NASA Astrophysics Data System (ADS)

Kang, Joonhee; Chung, Habin; Doh, Chilhoon; Kang, Byoungwoo; Han, Byungchan

2015-10-01

Understanding of the fundamental mechanisms causing significant enhancement of Li-ionic conductivity by Al3+ doping to a solid LiGe2(PO4)3 (LGP) electrolyte is pursued using first principles density functional theory (DFT) calculations combined with experimental measurements. Our results indicate that partial substitution Al3+ for Ge4+ in LiGe2(PO4)3 (LGP) with aliovalent (Li1+xAlxGe2-x(PO4)3, LAGP) improves the Li-ionic conductivity about four-orders of the magnitude. To unveil the atomic origin we calculate plausible diffusion paths of Li in LGP and LAGP materials using DFT calculations and a nudged elastic band method, and discover that LAGP had additional transport paths for Li with activation barriers as low as only 34% of the LGP. Notably, these new atomic channels manifest subtle electrostatic environments facilitating cooperative motions of at least two Li atoms. Ab-initio molecular dynamics predict Li-ionic conductivity for the LAGP system, which is amazingly agreed experimental measurement on in-house made samples. Consequently, we suggest that the excess amounts of Li caused by the aliovalent Al3+ doping to LGP lead to not only enhancing Li concentration but also opening new conducting paths with substantially decreases activation energies and thus high ionic conductivity of LAGP solid-state electrolyte.

Urethral pressure reflectometry during intra-abdominal pressure increase-an improved technique to characterize the urethral closure function in continent and stress urinary incontinent women.

PubMed

Saaby, Marie-Louise; Klarskov, Niels; Lose, Gunnar

2013-11-01

to assess the urethral closure function by urethral pressure reflectometry (UPR) during intra-abdominal pressure-increase in SUI and continent women. Twenty-five urodynamically proven SUI women and eight continent volunteer women were assessed by ICIQ-SF, pad-weighing test, incontinence diary, and UPR. UPR was conducted during resting and increased intra-abdominal pressure (P(Abd)) by straining. Related values of P(Abd) and urethral opening pressure (P(o)) were plotted into an abdomino-urethral pressuregram. Linear regression of the values was conducted, and the slope of the line ("APIR") and the intercept with the y-axis found. By the equation of the line, Po was calculated for various values of P(Abd), for example, 50 cm H2O (P(o-Abd 50)). The resting P(o) (P(o-rest)) and APIR, respectively, significantly differed in SUI and continent women but could not separate the two groups. The urethral closure equation (UCE) based on P(o-rest) and APIR provided a more detailed characterization of a woman's closure function based on the permanent closure forces (primarily generated by the urethral sphincteric unit) and the adjunctive closure forces (primarily generated by the support system). P(o-Abd 50) and UCE, respectively, which express the combined permanent and adjunctive closure forces and estimate the efficiency of the closure function, separated SUI and continent women and were highly significantly negatively correlated with ICIQ-SF, pad test, and the number of incontinence episodes. New parameters for characterization of the urethral closure function and possible dysfunctions and its efficiency were provided. P(o-Abd 50) and UCE may be used as diagnostic tests and severity measures. © 2013 Wiley Periodicals, Inc.

Why O2 Is Required by Complex Life on Habitable Planets and the Concept of Planetary "Oxygenation Time"

NASA Astrophysics Data System (ADS)

Catling, David C.; Glein, Christopher R.; Zahnle, Kevin J.; McKay, Christopher P.

2005-06-01

Life is constructed from a limited toolkit: the Periodic Table. The reduction of oxygen provides the largest free energy release per electron transfer, except for the reduction of fluorine and chlorine. However, the bonding of O2 ensures that it is sufficiently stable to accumulate in a planetary atmosphere, whereas the more weakly bonded halogen gases are far too reactive ever to achieve significant abundance. Consequently, an atmosphere rich in O2 provides the largest feasible energy source. This universal uniqueness suggests that abundant O2 is necessary for the high-energy demands of complex life anywhere, i.e., for actively mobile organisms of ~10-1-100 m size scale with specialized, differentiated anatomy comparable to advanced metazoans. On Earth, aerobic metabolism provides about an order of magnitude more energy for a given intake of food than anaerobic metabolism. As a result, anaerobes do not grow beyond the complexity of uniseriate filaments of cells because of prohibitively low growth efficiencies in a food chain. The biomass cumulative number density, n, at a particular mass, m, scales as n (>m)~m-1 for aquatic aerobes, and we show that for anaerobes the predicted scaling is n~m -1.5, close to a growth-limited threshold. Even with aerobic metabolism, the partial pressure of atmospheric O2 (PO2) must exceed ~103 Pa to allow organisms that rely on O2 diffusion to evolve to a size ~10-3 m. PO2 in the range ~103-104 Pa is needed to exceed the threshold of ~10-2 m size for complex life with circulatory physiology. In terrestrial life, O2 also facilitates hundreds of metabolic pathways, including those that make specialized structural molecules found only in animals. The time scale to reach PO2 ~104 Pa, or "oxygenation time," was long on the Earth (~3.9 billion years), within almost a factor of 2 of the Sun's main sequence lifetime. Consequently, we argue that the oxygenation time is likely to be a key rate-limiting step in the evolution of complex life on other habitable planets. The oxygenation time could preclude complex life on Earth-like planets orbiting short-lived stars that end their main sequence lives before planetary oxygenation takes place. Conversely, Earth-like planets orbiting long-lived stars are potentially favorable habitats for complex life.

Local structures in mixed Li{sub x}Fe{sub 1−y}M{sub y}PO{sub 4} (M=Co, Ni) electrode materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jalkanen, K.; Lindén, J.; Karppinen, M., E-mail: maarit.karppinen@aalto.fi

We employ {sup 57}Fe Mössbauer spectroscopy as a local tool to probe electrical environments of Fe{sup 2+} and Fe{sup 3+} at different lithiation (x) and cation-substitution (y) levels in Li{sub x}Fe{sub 1−y}M{sub y}PO{sub 4}/C (M=Co, Ni) Li-ion battery electrode materials. Upon delithiation the local environment of Fe{sup 3+} remains unaffected for the parent y=0 system due to the LiFePO{sub 4}/FePO{sub 4} phase separation, whereas for y>0 changes in the electrical environment are seen for Fe{sup 3+}. When the Fe{sup 2+}/Fe{sup 3+} redox couple is partially-delithiated, a decreasing quadrupole splitting value is observed for Fe{sup 3+} with increasing y, implying amore » more symmetric electrical environment. The increasing concentration of the Co{sup 2+}/Ni{sup 2+} substituent introduces increasing amounts of Li atoms in the Fe{sup 3+}-containing phase, and these nearest-neighbor Li atoms are suspected to cause the changes seen in the local environment of Fe{sup 3+}. - Graphical abstract: Local environment of iron in Li{sub x}Fe{sub 1−y}(Co/Ni){sub y}PO{sub 4} is studied by {sup 57}Fe Mössbauer spectroscopy at different lithiation (x) and cation-substitution (y) levels. - Highlights: • Local Fe environment in Li{sub x}Fe{sub 1−y}(Co/Ni){sub y}PO{sub 4} is studied by {sup 57}Fe Mössbauer spectroscopy. • Co/Ni-for-Fe substitution results in a more symmetric electrical environment for Fe{sup 3+}. • Due to presence of Co{sup 2+}/Ni{sup 2+}, Li atoms are introduced into the Fe{sup 3+}-containing phase. • These nearest-neighbor Li atoms are suggested to change the local Fe{sup 3+} environment.« less

High rate reactive sputtering of MoN(x) coatings

NASA Technical Reports Server (NTRS)

Rudnik, Paul J.; Graham, Michael E.; Sproul, William D.

1991-01-01

High rate reactive sputtering of MoN(x) films was performed using feedback control of the nitorgen partial pressure. Coatings were made at four different target powers: 2.5, 5.0, 7.5 and 10 kW. No hysteresis was observed in the nitrogen partial pressure vs. flow plot, as is typically seen for the Ti-N system. Four phases were determined by X-ray diffraction: molybdenum, Mo-N solid solution, Beta-Mo2N and gamma-Mo2N. The hardness of the coatings depended upon composition, substrate bias, and target power. The phases present in the hardest films differed depending upon deposition parameters. For example, the Beta-Mo2N phase was hardest (load 25 gf) at 5.0 kW with a value of 3200 kgf/sq mm, whereas the hardest coatings at 10 kW were the gamma-Mo2N phase (3000 kgf/sq mm). The deposition rate generally decreased with increasing nitrogen partial pressure, but there was a range of partial pressures where the rate was relatively constant. At a target power of 5.0 kW, for example, the deposition rates were 3300 A/min for a N2 partial pressure of 0.05 - 1.0 mTorr.

Effects of calcium and phosphate on uranium(IV) oxidation: Comparison between nanoparticulate uraninite and amorphous U IV–phosphate

DOE PAGES

Latta, Drew E.; Kemner, Kenneth M.; Mishra, Bhoopesh; ...

2015-11-17

The mobility of uranium in subsurface environments depends strongly on its redox state, with U IV phases being significantly less soluble than U VI minerals. This study compares the oxidation kinetics and mechanisms of two potential products of U VI reduction in natural systems, a nanoparticulate UO 2 phase and an amorphous U IV–Ca–PO 4 analog to ningyoite (CaU IV(PO 4) 2·1–2H 2O). The valence of U was tracked by X-ray absorption near-edge spectroscopy (XANES), showing similar oxidation rate constants for U IVO 2 and U IV–phosphate in solutions equilibrated with atmospheric O 2 and CO 2 at pH 7.0more » (k obs,UO2 = 0.17 ± 0.075 h -1 vs. k obs,U IV PO4 = 0.30 ± 0.25 h -1). Addition of up to 400 μM Ca and PO 4 decreased the oxidation rate constant by an order of magnitude for both UO 2 and U IV–phosphate. The intermediates and products of oxidation were tracked by electron microscopy, powder X-ray diffraction (pXRD), and extended X-ray absorption fine-structure spectroscopy (EXAFS). In the absence of Ca or PO 4, the product of UO 2 oxidation is Na–uranyl oxyhydroxide (under environmentally relevant concentrations of sodium, 15 mM NaClO 4 and low carbonate concentration), resulting in low concentrations of dissolved U VI (<2.5 × 10 -7 M). Oxidation of U IV–phosphate produced a Na-autunite phase (Na 2(UO 2)PO 4·xH 2O), resulting in similarly low dissolved U concentrations (<7.3 × 10 -8 M). When Ca and PO 4 are present in the solution, the EXAFS data and the solubility of the UVI phase resulting from oxidation of UO 2 and UIV–phosphate are consistent with the precipitation of Na-autunite. Bicarbonate extractions and Ca K-edge X-ray absorption spectroscopy of oxidized solids indicate the formation of a Ca–UVI–PO 4 layer on the UO 2 surface and suggest a passivation layer mechanism for the decreased rate of UO 2 oxidation in the presence of Ca and PO 4. Interestingly, the extractions were unable to remove all of the oxidized U from partially oxidized UO 2 solids, suggesting that oxidized U is distributed between the interior of the UO 2 nanoparticles and the labile surface layer. Accounting for the entire pool of oxidized U by XANES is the likely reason for the higher UO 2 oxidation rate constants determined here relative to prior studies. In conclusion, our results suggest that the natural presence or addition of Ca and PO 4 in groundwater could slow the rates of U IV oxidation, but that the rates are still fast enough to cause complete oxidation of U IV within days under fully oxygenated conditions.« less

Biomass hydrolysis inhibition at high hydrogen partial pressure in solid-state anaerobic digestion.

PubMed

Cazier, E A; Trably, E; Steyer, J P; Escudie, R

2015-08-01

In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

Low temperature time resolved photoluminescence in ordered and disordered Cu2ZnSnS4 single crystals

NASA Astrophysics Data System (ADS)

Raadik, Taavi; Krustok, Jüri; Kauk-Kuusik, M.; Timmo, K.; Grossberg, M.; Ernits, K.; Bleuse, J.

2017-03-01

In this work we performed time-resolved micro-photoluminescence (TRPL) studies of Cu2ZnSnS4 (CZTS) single crystals grown in molten KI salt. The order/disorder degree of CZTS was varied by the thermal post treatment temperature. Photoluminescence spectra measured at T=8 K showed an asymmetric band with a peak position of 1.33 eV and 1.27 eV for partially ordered and disordered structures, respectively. Thermal activation energies were found to be ET (PO) =65±9 meV for partially ordered and ET (PD) =27±4 meV for partially disordered. These low activation energy values indicating to the defect cluster recombination model for both partially ordered and disordered structures. TRPL was measured for both crystals and their decay curves were fitted with a stretched exponential function, in order to describe the charge carriers' recombination dynamics at low temperature.

A sodium gallophosphate with an original tunnel structure: NaGa 2(OH)(PO 4) 2

NASA Astrophysics Data System (ADS)

Guesdon, A.; Monnin, Y.; Raveau, B.

2003-05-01

A new sodium gallophosphate, NaGa 2(OH)(PO 4) 2, has been obtained by hydrothermal synthesis under autogeneous pressure at 473 K. It crystallizes in the P2 1/ n space group with the cell parameters a=8.9675(8) Å, b=8.9732(5) Å, c=9.2855(7) Å, β=114.812(6)°, V=678.2 Å 3 ( Z=4). In its original three-dimensional framework, monophosphate groups share their apices with [Ga 4O 16(OH) 2] tetrameric units, which are built from two GaO 5(OH) octahedra and two GaO 4(OH) trigonal bipyramids. The sodium cations are located in tunnels running along a, whereas the tunnels running along b are empty.

Influence of In Vitro and In Vivo Oxygen Modulation on β Cell Differentiation From Human Embryonic Stem Cells

PubMed Central

Cechin, Sirlene; Álvarez-Cubela, Silvia; Giraldo, Jaime A.; Molano, Ruth D.; Villate, Susana; Ricordi, Camillo; Pileggi, Antonello; Inverardi, Luca

2014-01-01

The possibility of using human embryonic stem (hES) cell-derived β cells as an alternative to cadaveric islets for the treatment of type 1 diabetes is now widely acknowledged. However, current differentiation methods consistently fail to generate meaningful numbers of mature, functional β cells. In order to address this issue, we set out to explore the role of oxygen modulation in the maturation of pancreatic progenitor (PP) cells differentiated from hES cells. We have previously determined that oxygenation is a powerful driver of murine PP differentiation along the endocrine lineage of the pancreas. We hypothesized that targeting physiological oxygen partial pressure (pO2) levels seen in mature islets would help the differentiation of PP cells along the β-cell lineage. This hypothesis was tested both in vivo (by exposing PP-transplanted immunodeficient mice to a daily hyperbaric oxygen regimen) and in vitro (by allowing PP cells to mature in a perfluorocarbon-based culture device designed to carefully adjust pO2 to a desired range). Our results show that oxygen modulation does indeed contribute to enhanced maturation of PP cells, as evidenced by improved engraftment, segregation of α and β cells, body weight maintenance, and rate of diabetes reversal in vivo, and by elevated expression of pancreatic endocrine makers, β-cell differentiation yield, and insulin production in vitro. Our studies confirm the importance of oxygen modulation as a key variable to consider in the design of β-cell differentiation protocols and open the door to future strategies for the transplantation of fully mature β cells. PMID:24375542

Novel therapy in multiple myeloma.

PubMed

Avilés, Agustin; Neri, Natividad; Nambo, M Jesús; Cleto, Sergio; Castañeda, Claudia; González, Martha; Talavera, Alejandra; Huerta-Guzmán, Judith

2005-10-01

Treatment in patients with multiple myeloma remain to be defined. Younger patients (defined as a cut-off level < 65 years old) will be treated with chemotherapy and transplant procedures. However, most patients > 65 years old are not candidates for this therapeutic approach and the use of intensive chemotherapy could be associated to severe toxicity. We developed an new, not-cytotoxic regimen with dexamethasone 30 mg/m(2), iv, days 1 to 4, all trans retinoic acid 45 mg/m(2), po, days 5 to 14 and interferon alfa 2a 4.5 MU, sc, daily, days 5 to 14 (DAI regimen) administered every 28 days in number of 6 cycles, at this point patients were restaging, if they showed complete response, objective response or partial response they were conducted to received thalidomide 100-200 mg po, daily and dexamethasone 10 mg/2, po days 1 to 4 at monthly intervals, for 18 months. Forty one patients were enrolled in an Phase II study. In an intent to treat analysis all patients were evaluable. Complete response was observed in 18 cases (43%), objective response in 10 patients (24%) and partial response in 5 patients (12%), overall response rate was 80%. Eight patients were considered failures. At an median of 36 months, no relapse of progression disease has been observed, thus actuarial curves at 3-years showed that event free survival is 100% and overall survival is 91%. Toxicity was mild, all patients received the planned dose in time. This regimen appear to be useful in older patients with multiple myeloma, the response rate is higher and toxicity was mild. Controlled clinical trials comparing with conventional chemotherapy will be conducted to define the role of this therapeutic approach.

Measuring Ancient Air Pressure Using Fossilized Cyanobacteria

NASA Astrophysics Data System (ADS)

Silverman, S. N.; Som, S. M.; Gordon, R.; Bebout, B.

2016-12-01

The evolution of Earth's atmosphere has been governed by biological evolution. The dominant air component, nitrogen, has undergone substantial variation over geological time. Today, the partial pressure of nitrogen is 0.79 bar, but this value could have been much higher during early Earth1. The nitrogen partial pressure is postulated to have dropped to a maximum of 0.5 bar before the Great Oxidation Event 2.4 billion years ago, and subsequently recovered to the 0.8 bar value of our modern atmosphere over the next 330 million years2. We are placing constraints on the trajectory of this recovery by investigating how nitrogen partial pressure influences the morphology of a certain species of filamentous cyanobacteria that has been found fossilized in 2 billion year old rocks. These filamentous cyanobacteria convert nitrogen from its dissolved gaseous state (N2) to a biologically useful state (i.e. NH3) when the latter is present at growth-limiting concentrations in their aquatic environment. Such cyanobacteria develop heterocysts (specialized, visually distinct cells), which fix the nitrogen and laterally distribute it to neighboring cells along the one-dimensional filament. We suggest that the distance between heterocysts reflects the nitrogen partial pressure dissolved in water, which is related to atmospheric pN2 by Henry's law. In the laboratory, we are quantifying the relationship between heterocyst distance, variance and covariance to atmospheric pN2 by subjecting cyanobacteria (in media devoid of nitrate) to different partial pressures of N2 at a constant temperature and lighting for the representative species Anabaena variabilis. As far as we know, such experiments have not been previously conducted. This new geobarometer will complement existing methods of quantifying ancient nitrogen partial pressure. 1Goldblatt, Colin, et al. "Nitrogen-enhanced greenhouse warming on early Earth." Nature Geoscience 2 (2009): 891-896. 2Som, S., et al. "Earth's air pressure 2.7 billion years ago constrained to less than half of modern levels." Nature Geoscience 9 (2016): 448-451.

Cerebral Hemodynamic Effects of Acute Hyperoxia and Hyperventilation after Severe Traumatic Brain Injury

PubMed Central

Rangel-Castilla, Leonardo; Lara, Lucia Rivera; Gopinath, Shankar; Swank, Paul R.; Valadka, Alex

2010-01-01

Abstract The purpose of this study was to examine the effects of hyperventilation or hyperoxia on cerebral hemodynamic parameters over time in patients with severe traumatic brain injury (TBI). We prospectively studied 186 patients with severe TBI. CO2 and O2 reactivity tests were conducted twice a day on days 1–5 and once daily on days 6–10 after injury. During hyperventilation there was a significant decrease in intracranial pressure (ICP), mean arterial pressure (MAP), jugular venous oxygen saturation (Sjvo2), brain tissue Po2 (Pbto2), and flow velocity (FV). During hyperoxia there was an increase in Sjvo2 and Pbto2, and a small but consistent decrease in ICP, end-tidal carbon dioxide (etco2), partial arterial carbon dioxide pressure (Paco2), and FV. Brain tissue oxygen reactivity during the first 12 h after injury averaged 19.7 ± 3.0%, and slowly decreased over the next 7 days. The autoregulatory index (ARI; normal = 5.3 ± 1.3) averaged 2.2 ± 1.5 on day 1 post-injury, and gradually improved over the 10 days of monitoring. The ARI significantly improved during hyperoxia, by an average of 0.4 ± 1.8 on the left, and by 0.5 ± 1.8 on the right. However, the change in ARI with hyperoxia was much smaller than that observed with hyperventilation. Hyperventilation increased ARI by an average of 1.3 ± 1.9 on the left, and 1.5 ± 2.0 on the right. Pressure autoregulation, as assessed by dynamic testing, was impaired in these head-injured patients. Acute hyperoxia significantly improved pressure autoregulation, although the effect was smaller than that induced by hyperventilation. The very small change in Paco2 induced by hyperoxia does not appear to explain this finding. Rather, the vasoconstriction induced by acute hyperoxia may allow the cerebral vessels to respond better to transient hypotension. Further studies are needed to define the clinical significance of these observations. PMID:20684672

Effect of O 2 gas partial pressure on structures and dielectric characteristics of rf sputtered ZrO 2 thin films

NASA Astrophysics Data System (ADS)

Ma, C. Y.; Lapostolle, F.; Briois, P.; Zhang, Q. Y.

2007-08-01

Amorphous and polycrystalline zirconium oxide thin films have been deposited by reactive rf magnetron sputtering in a mixed argon/oxygen or pure oxygen atmosphere with no intentional heating of the substrate. The films were characterized by high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and capacitance versus voltage ( C- V) measurements to investigate the variation of structure, surface morphology, thickness of SiO 2-like interfacial layer as well as dielectric characteristics with different oxygen partial pressures. The films deposited at low oxygen partial pressures (less than 15%) are amorphous and dense with a smooth surface. In contrast, the films prepared at an oxygen partial pressure higher than 73% are crystallized with the microstructure changing from the mixture of monoclinic and tetragonal phases to a single monoclinic structure. The film structural transition is believed to be consequences of decrease in the oxygen vacancy concentration in the film and of increase of the energetically neutral particles in the plasma due to an increased oxygen partial pressure. SE measurements showed that significant interfacial SiO 2 growth has taken place above approximately 51%. The best C- V results in terms of relative dielectric constant values are obtained for thin films prepared at an oxygen partial pressure of 15%.

Reversible effects of oxygen partial pressure on genes associated with placental angiogenesis and differentiation in primary-term cytotrophoblast cell culture.

PubMed

Debiève, F; Depoix, C; Gruson, D; Hubinont, C

2013-09-01

Timely regulated changes in oxygen partial pressure are important for placental formation. Disturbances could be responsible for pregnancy-related diseases like preeclampsia and intrauterine growth restriction. We aimed to (i) determine the effect of oxygen partial pressure on cytotrophoblast differentiation; (ii) measure mRNA expression and protein secretion from genes associated with placental angiogenesis; and (iii) determine the reversibility of these effects at different oxygen partial pressures. Term cytotrophoblasts were incubated at 21% and 2.5% O2 for 96 hr, or were switched between the two oxygen concentrations after 48 hr. Real-time PCR and enzyme-linked immunosorbent assays (ELISAs) were used to evaluate cell fusion and differentiation, measuring transcript levels for those genes involved in cell fusion and placental angiogenesis, including VEGF, PlGF, VEGFR1, sVEGFR1, sENG, INHA, and GCM1. Cytotrophoblasts underwent fusion and differentiation in 2.5% O2 . PlGF expression was inhibited while sVEGFR1 expression increased. VEGF and sENG mRNA expressions increased in 2.5% compared to 21% O2 , but no protein was detected in the cell supernatants. Finally, GCM1 mRNA expression increased during trophoblast differentiation at 21% O2 , but was inhibited at 2.5% O2 . These mRNA expression effects were reversed by returning the cells to 21% O2 . Thus, low-oxygen partial pressure does not inhibit term-cytotrophoblast cell fusion and differentiation in vitro. Lowering the oxygen partial pressure from 21% to 2.5% caused normal-term trophoblasts to reversibly modify their expression of genes associated with placental angiogenesis. This suggests that modifications observed in pregnancy diseases such as preeclampsia or growth retardation are probably due to an extrinsic effect on trophoblasts. Copyright © 2013 Wiley Periodicals, Inc.

Discrimination of magnoliae officinalis cortex based on the quantitative profiles of magnolosides by two-channel liquid chromatography with electrochemical detection.

PubMed

Xue, Zhenzhen; Kotani, Akira; Yang, Bin; Hakamata, Hideki

2018-05-31

A two-channel liquid chromatography with electrochemical detection system (2LC-ECD) was newly designed for the simultaneous determination of magnolosides A, B, F, H, and L in the first channel and other magnolosides D and M in the second channel, respectively. Peak heights had linear relationships to the magnoloside concentrations in a range of 0.02-16 μmol/L for H, 0.01-12 μmol/L for A, 0.02-12 μmol/L for F and L, 0.01-8 μmol/L for B, 0.002-6 μmol/L for D, and 0.002-4 μmol/L for M, respectively. Seven magnolosides in magnoliae officinalis cortex (MOC) were determined by the 2LC-ECD, and the obtained quantitative profiles of magnolosides were applied to the discrimination between the MOC samples harvested from Hubei and Sichuan (called Chuan po) and from Zhejiang and Fujian (called Wen po). By principal component analysis (PCA) and supervised partial least squares discriminant analysis (PLS-DA) based on the quantitative profiles of the magnolosides, Chuan po were clearly discriminated from Wen po on the plots obtained from our multivariable analyses. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluating the effect of sample type on American alligator ( Alligator mississippiensis) analyte values in a point-of-care blood analyser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamilton, Matthew T.; Finger, John W.; Winzeler, Megan E.

The assessment of wildlife health has been enhanced by the ability of point-of-care (POC) blood analysers to provide biochemical analyses of non-domesticated animals in the field. However, environmental limitations (e.g. temperature, atmospheric humidity and rain) and lack of reference values may inhibit researchers from using such a device with certain wildlife species. Evaluating the use of alternative sample types, such as plasma, in a POC device may afford researchers the opportunity to delay sample analysis and the ability to use banked samples. In this study, we examined fresh whole blood, fresh plasma and frozen plasma (sample type) pH, partial pressuremore » of carbon dioxide (PCO 2), bicarbonate (HCO 3₋), total carbon dioxide (TCO 2), base excess (BE), partial pressure of oxygen (PO 2), oxygen saturation (sO 2) and lactate concentrations in 23 juvenile American alligators (Alligator mississippiensis) using an i-STAT CG4+ cartridge. Our results indicate that sample type had no effect on lactate concentration values (F 2,65 = 0.37, P = 0.963), suggesting that the i-STAT analyser can be used reliably to quantify lactate concentrations in fresh and frozen plasma samples. In contrast, the other seven blood parameters measured by the CG4+ cartridge were significantly affected by sample type. In conclusion, we were able to collect blood samples from all alligators within 2 min of capture to establish preliminary reference ranges for juvenile alligators based on values obtained using fresh whole blood.« less

Evaluating the effect of sample type on American alligator ( Alligator mississippiensis) analyte values in a point-of-care blood analyser

DOE PAGES

Hamilton, Matthew T.; Finger, John W.; Winzeler, Megan E.; ...

2016-01-01

The assessment of wildlife health has been enhanced by the ability of point-of-care (POC) blood analysers to provide biochemical analyses of non-domesticated animals in the field. However, environmental limitations (e.g. temperature, atmospheric humidity and rain) and lack of reference values may inhibit researchers from using such a device with certain wildlife species. Evaluating the use of alternative sample types, such as plasma, in a POC device may afford researchers the opportunity to delay sample analysis and the ability to use banked samples. In this study, we examined fresh whole blood, fresh plasma and frozen plasma (sample type) pH, partial pressuremore » of carbon dioxide (PCO 2), bicarbonate (HCO 3₋), total carbon dioxide (TCO 2), base excess (BE), partial pressure of oxygen (PO 2), oxygen saturation (sO 2) and lactate concentrations in 23 juvenile American alligators (Alligator mississippiensis) using an i-STAT CG4+ cartridge. Our results indicate that sample type had no effect on lactate concentration values (F 2,65 = 0.37, P = 0.963), suggesting that the i-STAT analyser can be used reliably to quantify lactate concentrations in fresh and frozen plasma samples. In contrast, the other seven blood parameters measured by the CG4+ cartridge were significantly affected by sample type. In conclusion, we were able to collect blood samples from all alligators within 2 min of capture to establish preliminary reference ranges for juvenile alligators based on values obtained using fresh whole blood.« less

Structural and physical properties of transparent conducting, amorphous Zn-doped SnO2 films

NASA Astrophysics Data System (ADS)

Zhu, Q.; Ma, Q.; Buchholz, D. B.; Chang, R. P. H.; Bedzyk, M. J.; Mason, T. O.

2014-01-01

The structural and physical properties of conducting amorphous Zn-doped SnO2 (a-ZTO) films, prepared by pulsed laser deposition, were investigated as functions of oxygen deposition pressure (pO2), composition, and thermal annealing. X-ray scattering and X-ray absorption spectroscopy measurements reveal that at higher pO2, the a-ZTO films are highly transparent and have a structural framework similar to that found in crystalline (c-), rutile SnO2 in which the Sn4+ ion is octahedrally coordinated by 6 O2- ions. The Sn4+ ion in these films however has a coordination number (CN) smaller by 2%-3% than that in c-SnO2, indicating the presence of oxygen vacancies, which are the likely source of charge carriers. At lower pO2, the a-ZTO films show a brownish tint and contain some 4-fold coordinated Sn2+ ions. Under no circumstances is the CN around the Zn2+ ion larger than 4, and the Zn-O bond is shorter than the Sn-O bond by 0.07 Å. The addition of Zn has no impact on the electroneutrality but improves significantly the thermal stability of the films. Structural changes due to pO2, composition, and thermal annealing account well for the changes in the physical properties of a-ZTO films.

Effects of acupuncture on tissue-oxygenation of the rat brain.

PubMed

Chen, G S; Erdmann, W

1977-01-01

Acupuncture has been claimed to be effective in restoring consciousness in some comatose patients. Possible mechanisms to explain alleged acupuncture-induced arousal may include vasodilatory effects caused by sympathetic stimulation which leads to an augmentation of cerebral microcirculation and thereby improves oxygen supply to the brain tissue. Experiments were performed in ten albino rats (Wistar) employing PO2 microelectrodes which were inserted into the cortex of the animals through small burholes. Brain tissue PO2 was continuously recorded before, during, and after acupuncture. Stimulation of certain acupuncture loci (Go-26) resulted in immediate increase of PO2 in the frontal cortex of the rat brain. This effect was reproducible. The effect was comparable to that obtained with increase of inspiratory CO2 known to induce arterial vasodilatation and thus capillary perfusion pressure. The effect was more significant as compared to tissue PO2 increases obtained after increase of inspiratory oxygen concentration from 21% to 100%. It appears that acupuncture causes an increase of brain tissue perfusion which may be, at least in part, responsible for arousal of unconscious patients. Dilatation of cerebral vascular vessels and improvement of autoregulation in the brain by acupuncture stimulation may also explain the effectiveness of acupuncture in the treatment of migraine headache.

Spin-orbit interaction and Kondo scattering at the PrAlO3/SrTiO3 interface: effects of oxygen content

NASA Astrophysics Data System (ADS)

Mozaffari, Shirin; Guchhait, Samaresh; Markert, John T.

2017-10-01

We report the effects of oxygen pressure during growth (PO2 ) on the electronic and magnetic properties of PrAlO3 films grown on TiO2 -terminated SrTiO3 substrates. Resistivity measurements show an increase in the sheet resistance as PO2 is increased. The saturation of the sheet resistance down to 0.3 K is consistent with Kondo theory for PO2 ≥slant 10-5 torr. Resistivity data fits indicate Kondo temperatures of 16-18 K. For the 10-4 sample, we measured a moderate positive magnetoresistance (MR) due to a strong spin-orbit (SO) interaction at low magnetic fields that evolves into a larger negative MR at high fields due to the Kondo effect. Analysis of the MR data permitted the extraction of the SO interaction critical field for the PO2=10-5 torr interface ( H_SO=1.25 T). We observed high positive MR for the least oxygenated sample, where a fraction of the n-type carriers are derived from oxygen vacancies and possible cation interdiffusion; for this 6×10-6 torr sample, Hall effect data indicate a thick conducting layer. Its extremely high MR (˜400% ) is attributed to classical behavior due to a distribution of mobilities.

A Lewis acid β-diiminato-zinc-complex as all-rounder for co- and terpolymerisation of various epoxides with carbon dioxide.

PubMed

Reiter, M; Vagin, S; Kronast, A; Jandl, C; Rieger, B

2017-03-01

A β-diiminato-zinc-N(SiMe 3 ) 2 complex ( 1 ) was synthesised and fully characterised, including an X-ray diffraction study. The activity of catalyst 1 towards the coupling reaction of CO 2 and various epoxides, including propylene oxide (PO), cyclohexene oxide (CHO), styrene oxide (SO), limonene oxide (LO), octene oxide (OO) and epichlorohydrin (ECH), was investigated. Terpolymerisation of CO 2 , PO and LO, as well as CO 2 , CHO and PO, was successfully realised, resulting in polymers with adjustable glass transition temperatures and transparencies. Reaction conditions such as temperature, pressure and catalyst concentration were varied to find the optimal reaction values, especially regarding LO/CO 2 . In situ IR experiments hinted that at 60 °C and a critical LO concentration, polymerisation and depolymerisation are in an equilibrium (ceiling effect). Pressurising catalyst 1 with carbon dioxide resulted in a dimeric catalyst ( 2 ) with a OSiMe 3 group as a new initiator. Homopolymerisation of different epoxides was carried out in order to explain the reactivity concerning copolymerisation reaction of CO 2 and epoxides.

Chemical Imaging of Nanoscale Interfacial Inhomogeneity in LiFePO4 Composite Electrodes from a Cycled Large-Format Battery.

PubMed

Zhou, Jigang; Wang, Jian; Hu, Yongfeng; Lu, Mi

2017-11-15

The nanoscale interfacial inhomogeneity in a cycled large-format LiFePO 4 (LFP) composite electrode has been studied by X-ray photoemission electron microscopy at single particle spatial resolution with a probe depth of ∼5 nm. The loss of active lithium in cycled LFP causes the coexsitence of fully delithiated LFP (FePO 4 ) and partially delithiated LFP (Li 0.6 FePO 4 or Li 0.8 FePO 4 ) as a function of the extent of lithium loss. The distribution of various lithium loss phases along with local agglomeration of LFP and degradation of binder and carbon black are correlatively visualized. This is the first experimental exploration of chemical interplay between components in the composite electrode from a large-format battery, and implications on the LFP degradation in this battery are discussed.

Atmospheric carbon dioxide concentrations before 2.2 billion years ago

NASA Technical Reports Server (NTRS)

Rye, R.; Kuo, P. H.; Holland, H. D.

1995-01-01

The composition of the Earth's early atmosphere is a subject of continuing debate. In particular, it has been suggested that elevated concentrations of atmospheric carbon dioxide would have been necessary to maintain normal surface temperatures in the face of lower solar luminosity in early Earth history. Fossil weathering profiles, known as palaeosols, have provided semi-quantitative constraints on atmospheric oxygen partial pressure (pO2) before 2.2 Gyr ago. Here we use the same well studied palaeosols to constrain atmospheric pCO2 between 2.75 and 2.2 Gyr ago. The observation that iron lost from the tops of these profiles was reprecipitated lower down as iron silicate minerals, rather than as iron carbonate, indicates that atmospheric pCO2 must have been less than 10(-1.4) atm--about 100 times today's level of 360 p.p.m., and at least five times lower than that required in one-dimensional climate models to compensate for lower solar luminosity at 2.75 Gyr. Our results suggest that either the Earth's early climate was much more sensitive to increases in pCO2 than has been thought, or that one or more greenhouse gases other than CO2 contributed significantly to the atmosphere's radiative balance during the late Archaean and early Proterozoic eons.

Structural and electronic transformations in substituted La-Sr manganites depending on cations and oxygen content

NASA Astrophysics Data System (ADS)

Karpasyuk, Vladimir; Badelin, Alexey; Merkulov, Denis; Derzhavin, Igor; Estemirova, Svetlana

2018-05-01

In the present research experimental data are obtained for the Jahn-Teller O‧ phase formation, phase transformation "orthorhombic-rhombohedral structure" and the change of the conductance type in the systems of manganites La3+1-c+xSr2+c-xMn3+1-c-x-2γMn4+c+2γZn2+xO3+γ, La3+1-c-xSr2+c+xMn3+1-c-x-2γMn4+c+2γGe4+xO3+γ, La3+1-cSr2+cMn3+1-x-c-2γMn4+c+2γ(Zn2+0.5Ge4+0.5)xO3+γ, where Mn4+ ions concentration is independent of "x". Ceramic samples were sintered in air at 1473 K. As-sintered samples had an excess of oxygen content. In order to provide stoichiometric oxygen content, the samples were annealed at 1223 K and partial pressure of oxygen PO2 = 10-1 Pа. Structural characteristics of the O‧ phase were obtained. The position of the phase boundary "orthorhombic-rhombohedral structure" and the temperature of the conductance type change depending on the cation composition of manganites and oxygen content were determined. Possible approaches to the interpretation of experimental results were suggested.

Multifunctional Structural Composite Batteries for U.S. Army Applications

DTIC Science & Technology

2008-12-01

capacity, electrical conductivity, rechargeability, and mechanical integrity. Lithium Iron Phosphate ( LiFePO4 ) is used as the active...intercalation material that provides electrochemical capacity. Commercially supplied LiFePO4 (Phostech Industries) was combined with an electrically...solvent system. The suspension was applied to the substrate and hot pressed at up to 200 °C and 900 kg of pressure The exact formulation of LiFePO4

Effects of calcium and phosphate on uranium(IV) oxidation: Comparison between nanoparticulate uraninite and amorphous UIV-phosphate

NASA Astrophysics Data System (ADS)

Latta, Drew E.; Kemner, Kenneth M.; Mishra, Bhoopesh; Boyanov, Maxim I.

2016-02-01

The mobility of uranium in subsurface environments depends strongly on its redox state, with UIV phases being significantly less soluble than UVI minerals. This study compares the oxidation kinetics and mechanisms of two potential products of UVI reduction in natural systems, a nanoparticulate UO2 phase and an amorphous UIV-Ca-PO4 analog to ningyoite (CaUIV(PO4)2·1-2H2O). The valence of U was tracked by X-ray absorption near-edge spectroscopy (XANES), showing similar oxidation rate constants for UIVO2 and UIV-phosphate in solutions equilibrated with atmospheric O2 and CO2 at pH 7.0 (kobs,UO2 = 0.17 ± 0.075 h-1 vs. kobs,UIVPO4 = 0.30 ± 0.25 h-1). Addition of up to 400 μM Ca and PO4 decreased the oxidation rate constant by an order of magnitude for both UO2 and UIV-phosphate. The intermediates and products of oxidation were tracked by electron microscopy, powder X-ray diffraction (pXRD), and extended X-ray absorption fine-structure spectroscopy (EXAFS). In the absence of Ca or PO4, the product of UO2 oxidation is Na-uranyl oxyhydroxide (under environmentally relevant concentrations of sodium, 15 mM NaClO4 and low carbonate concentration), resulting in low concentrations of dissolved UVI (<2.5 × 10-7 M). Oxidation of UIV-phosphate produced a Na-autunite phase (Na2(UO2)PO4·xH2O), resulting in similarly low dissolved U concentrations (<7.3 × 10-8 M). When Ca and PO4 are present in the solution, the EXAFS data and the solubility of the UVI phase resulting from oxidation of UO2 and UIV-phosphate are consistent with the precipitation of Na-autunite. Bicarbonate extractions and Ca K-edge X-ray absorption spectroscopy of oxidized solids indicate the formation of a Ca-UVI-PO4 layer on the UO2 surface and suggest a passivation layer mechanism for the decreased rate of UO2 oxidation in the presence of Ca and PO4. Interestingly, the extractions were unable to remove all of the oxidized U from partially oxidized UO2 solids, suggesting that oxidized U is distributed between the interior of the UO2 nanoparticles and the labile surface layer. Accounting for the entire pool of oxidized U by XANES is the likely reason for the higher UO2 oxidation rate constants determined here relative to prior studies. Our results suggest that the natural presence or addition of Ca and PO4 in groundwater could slow the rates of UIV oxidation, but that the rates are still fast enough to cause complete oxidation of UIV within days under fully oxygenated conditions.

Arterial supply, venous drainage and collateral circulation in the nose of the anaesthetized dog.

PubMed Central

Lung, M A; Wang, J C

1987-01-01

1. In pentobarbitone-anaesthetized dogs, nasal blood flows were measured with electromagnetic flow sensors. 2. The terminal internal maxillary artery was found to supply 22 +/- 2.2 ml min-1 (one side) to the nasal mucosa via the sphenopalatine and major palatine branches; the artery was found to receive multiple supply routes from common carotid, vertebral and subclavian arteries. 3. Nasal mucosa was found to receive collateral flow from contralateral terminal internal maxillary artery (about 5 to 10% of normal flow) and branches of subclavian arteries (about 36% of normal flow). 4. Nasal mucosa was found to have two venous systems: the low-flow (12 +/- 1.0 ml min-1; both sides) and low-pressure (7 +/- 0.6 mmHg) sphenopalatine veins draining the posterior nasal cavity and the high-flow (30 +/- 1.4 ml min-1; both sides) and high-pressure (17 +/- 1.0 mmHg) dorsal nasal veins draining the anterior nasal cavity. 5. PO2 of nasal venous blood was found to range from 62 +/- 2.9 mmHg to 65 +/- 3.4 mmHg. During nitrogen challenge to the nose, the sphenopalatine venous PO2 dropped to 35 +/- 3.0 mmHg while the dorsal nasal venous PO2 remained unchanged, suggesting that the sphenopalatine veins were responsible for draining capillary flow and dorsal nasal veins arteriovenous anastomotic flow as well. 6. Microscopic examination of the vascular casts confirmed that arteriovenous anastomoses were located only in the anterior nasal cavity. Images Fig. 5 Plate 1 Plate 2 PMID:3443958

Solubility of carbon dioxide in aqueous mixtures of alkanolamines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dawodu, O.F.; Meisen, A.

1994-07-01

The solubility of CO[sub 2] in water + N-methyldiethanolamine + monoethanolamine (MDEA + MEA) and water + N-methyldiethanolamine + diethanolamine (MDEA + DEA) are reported at two compositions of 3.4 M MDEA + 0.8 M MEA or DEA and 2.1 M MDEA + 2.1 M MEA or DEA at temperatures from 70 to 180 C and CO[sub 2] partial pressures from 100 to 3,850 kPa. The solubility of CO[sub 2] in the blends decreased with an increase in temperature but increased with an increase in CO[sub 2] partial pressure. At low partial pressures of CO[sub 2] and the same totalmore » amine concentration, the equilibrium CO[sub 2] loadings were in the order MDEA + MEA > MDEA + DEA > MDEA. However, at high CO[sub 2] partial pressures, the equilibrium CO[sub 2] loadings in the MDEA solutions were higher than those of the MDEA + MEA and MDEA + DEA blends of equal molar strengths due to the stoichiometric loading limitations of MEA and DEA. The nonadditivity of the equilibrium loadings for single amine systems highlights the need for independent measurements on amine blends.« less

Time-resolved EPR study of singlet oxygen in the gas phase.

PubMed

Ruzzi, Marco; Sartori, Elena; Moscatelli, Alberto; Khudyakov, Igor V; Turro, Nicholas J

2013-06-27

X-band EPR spectra of singlet O2((1)Δg) and triplet O2((3)Σg(-)) were observed in the gas phase under low molecular-oxygen pressures PO2 = 0.175-0.625 Torr, T = 293-323 K. O2((1)Δg) was produced by quenching of photogenerated triplet sensitizers naphthalene C8H10, perdeuterated naphthalene, and perfluoronaphthalene in the gas phase. The EPR spectrum of O2((1)Δg) was also observed under microwave discharge. Integrated intensities and line widths of individual components of the EPR spectrum of O2((3)Σg(-)) were used as internal standards for estimating the concentration of O2 species and PO2 in the EPR cavity. Time-resolved (TR) EPR experiments of C8H10 were the main focus of this Article. Pulsed irradiation of C8H10 in the presence of O2((3)Σg(-)) allowed us to determine the kinetics of formation and decay for each of the four components of the O2((1)Δg) EPR signal, which lasted for only a few seconds. We found that the kinetics of EPR-component decay fit nicely to a biexponential kinetics law. The TR EPR 2D spectrum of the third component of the O2((1)Δg) EPR spectrum was examined in experiments using C8H10. This spectrum vividly presents the time evolution of an EPR component. The largest EPR signal and the longest lifetime of O2((1)Δg), τ = 0.4 s, were observed at medium pressure PO2 = 0.4 Torr, T = 293 K. The mechanism of O2((1)Δg) decay in the presence of photosensitizers is discussed. EPR spectra of O2((1)Δg) evidence that the spin-rotational states of O2((1)Δg) are populated according to Boltzmann distribution in the studied time range of 10-100 ms. We believe that this is the first report dealing with the dependence of O2((1)Δg) EPR line width on PO2 and T.

Replaceable Sensor System for Bioreactor Monitoring

NASA Technical Reports Server (NTRS)

Mayo, Mike; Savoy, Steve; Bruno, John

2006-01-01

A sensor system was proposed that would monitor spaceflight bioreactor parameters. Not only will this technology be invaluable in the space program for which it was developed, it will find applications in medical science and industrial laboratories as well. Using frequency-domain-based fluorescence lifetime technology, the sensor system will be able to detect changes in fluorescence lifetime quenching that results from displacement of fluorophorelabeled receptors bound to target ligands. This device will be used to monitor and regulate bioreactor parameters including glucose, pH, oxygen pressure (pO2), and carbon dioxide pressure (pCO2). Moreover, these biosensor fluorophore receptor-quenching complexes can be designed to further detect and monitor for potential biohazards, bioproducts, or bioimpurities. Biosensors used to detect biological fluid constituents have already been developed that employ a number of strategies, including invasive microelectrodes (e.g., dark electrodes), optical techniques including fluorescence, and membrane permeable systems based on osmotic pressure. Yet the longevity of any of these sensors does not meet the demands of extended use in spacecraft habitat or bioreactor monitoring. It was therefore necessary to develop a sensor platform that could determine not only fluid variables such as glucose concentration, pO2, pCO2, and pH but can also regulate these fluid variables with controlled feedback loop.

Commercial Hy-Line W-36 pullet and laying hen venous blood gas and chemistry profiles utilizing the portable i-STAT®1 analyzer.

PubMed

Schaal, T P; Arango, J; Wolc, A; Brady, J V; Fulton, J E; Rubinoff, I; Ehr, I J; Persia, M E; O'Sullivan, N P

2016-02-01

Venous blood gas and chemistry reference ranges were determined for commercial Hy-Line W-36 pullets and laying hens utilizing the portable i-STAT®1 analyzer and CG8+ cartridges. A total of 632 samples were analyzed from birds between 4 and 110 wk of age. Reference ranges were established for pullets (4 to 15 wk), first cycle laying hens (20 to 68 wk), and second cycle (post molt) laying hens (70 to 110 wk) for the following traits: sodium (Na mmol/L), potassium (K mmol/L), ionized calcium (iCa mmol/L), glucose (Glu mg/dl), hematocrit (Hct% Packed Cell Volume [PCV]), pH, partial pressure carbon dioxide (PCO2 mm Hg), partial pressure oxygen (PO2 mm Hg), total concentration carbon dioxide (TCO2 mmol/L), bicarbonate (HCO3 mmol/L), base excess (BE mmol/L), oxygen saturation (sO2%), and hemoglobin (Hb g/dl). Data were analyzed using ANOVA to investigate the effect of production status as categorized by bird age. Trait relationships were evaluated by linear correlation and their spectral decomposition. All traits differed significantly among pullets and mature laying hens in both first and second lay cycles. Levels for K, iCa, Hct, pH, TCO2, HCO3, BE, sO2, and Hb differed significantly between first cycle and second cycle laying hens. Many venous blood gas and chemistry parameters were significantly correlated. The first 3 eigenvalues explained ∼2/3 of total variation. The first 2 principal components (PC) explained 51% of the total variation and indicated acid-balance and relationship between blood O2 and CO2. The third PC explained 16% of variation and seems to be related to blood iCa. Establishing reference ranges for pullet and laying hen blood gas and chemistry with the i-STAT®1 handheld unit provides a mechanism to further investigate pullet and layer physiology, evaluate metabolic disturbances, and may potentially serve as a means to select breeder candidates with optimal blood gas or chemistry levels on-farm. © The Author 2015. Published by Oxford University Press on behalf of the Poultry Science Association.

Very low H O H bending frequencies. IV. Fourier transform infrared spectra of synthetic dittmarite

NASA Astrophysics Data System (ADS)

Šoptrajanov, Bojan; Stefov, Viktor; Kuzmanovski, Igor; Jovanovski, Gligor; Lutz, H. Dieter; Engelen, Bernward

2002-08-01

The Fourier transform infrared spectra of MgNH 4PO 4·H 2O (the synthetic analogue of the mineral dittmarite) and of a series of its partially deuterated analogues have been studied as a part of our continuous work on compounds exhibiting very low water bending frequencies. Although, the presence of ammonium bands makes the assignments in this case more difficult than for the potassium analogues, the isomorphism between the compounds of the MNH 4PO 4·H 2O type (M=Mg, Co, Ni, Mn and one of the polymorphs of CdNH 4PO 4·H 2O) and those which contain potassium instead of ammonium as well as the careful analysis of the spectra warrant the conclusion that in the presently studied compound the water bending mode appears at a frequency which is far more than 100 cm -1 lower than in the gaseous water. The spectra clearly show that the ammonium ions in the structure are involved in quite strong hydrogen bonds, a characteristic which is a precondition for a material to behave as a protonic conductor.

Hydro-isomerization of n-hexane on bi-functional catalyst: Effect of total and hydrogen partial pressures

NASA Astrophysics Data System (ADS)

Thoa, Dao Thi Kim; Loc, Luu Cam

2017-09-01

The effect of both total pressure and hydrogen partial pressure during n-hexane hydro-isomerization over platinum impregnated on HZSM-5 was studied. n-Hexane hydro-isomerization was conducted at atmospheric pressure and 0.7 MPa to observe the influence of total pressure. In order to see the effect of hydrogen partial pressure, the reaction was taken place at different partial pressure of hydrogen varied from 307 hPa to 718 hPa by dilution with nitrogen to keep the total pressure at 0.1 MPa. Physico-chemical characteristics of catalyst were determined by the methods of nitrogen physi-sorption BET, SEM, XRD, TEM, NH3-TPD, TPR, and Hydrogen Pulse Chemi-sorption. Activity of catalyst in the hydro-isomerization of n-hexane was studied in a micro-flow reactor in the temperature range of 225-325 °C; the molar ratio H2/ hydrocarbon: 5.92, concentration of n-hexane: 9.2 mol.%, GHSV 2698 h-1. The obtained catalyst expressed high acid density, good reducing property, high metal dispersion, and good balance between metallic and acidic sites. It is excellent contact for n-hexane hydro-isomerization. At 250 °C, n-hexane conversion and selectivity were as high as 59-76 % and 85-99 %, respectively. It was found that catalytic activity was promoted either by total pressure or hydrogen partial pressure. At total pressure of 0.7 MPa while hydrogen partial pressure of 718 hPa, catalyst produced 63 RON liquid product containing friendly environmental iso-paraffins which is superior blending stock for green gasoline. Hydrogen did not only preserve catalyst actives by depressing hydrocracking and removing coke precursors but also facilitated hydride transfer step in the bi-functional bi-molecular mechanism.

Influence of the pressure applied to make LATP pellets

NASA Astrophysics Data System (ADS)

Lu, Xiaojuan

2018-02-01

NASICON structured Li1+xAlxTi2-x(PO4)3 (0.1≤x≤0.7) powders were prepared by hydrothermal synthesis method and the pressure applied to press the powders into pellets was investigated in this study. The conductivity was measured by an impedance analyzer and the microstructures were examined by SEM. The variation trend with Al amount was almost identical for LATP pressed at high pressure and low pressure. Both the total conductivities of LATP prepared at high pressures and low pressures peaked at x=0.6. The conductivities of LATP pressed at high pressures were all higher than those at low pressures. The reason was mainly attributed to the denser microstructures achieved at higher pressure.

Randomized trial of low versus high carbon dioxide insufflation pressures in posterior retroperitoneoscopic adrenalectomy.

PubMed

Fraser, Sheila; Norlén, Olov; Bender, Kyle; Davidson, Joanne; Bajenov, Sonya; Fahey, David; Li, Shawn; Sidhu, Stan; Sywak, Mark

2018-05-01

Posterior retroperitoneoscopic adrenalectomy has gained widespread acceptance for the removal of benign adrenal tumors. Higher insufflation pressures using carbon dioxide (CO 2 ) are required, although the ideal starting pressure is unclear. This prospective, randomized, single-blinded, study aims to compare physiologic differences with 2 different CO 2 insufflation pressures during posterior retroperitoneoscopic adrenalectomy. Participants were randomly assigned to a starting insufflation pressure of 20 mm Hg (low pressure) or 25 mm Hg (high pressure). The primary outcome measure was partial pressure of arterial CO 2 at 60 minutes. Secondary outcomes included end-tidal CO 2 , arterial pH, blood pressure, and peak airway pressure. Breaches of protocol to change insufflation pressure were permitted if required and were recorded. A prospective randomized trial including 31 patients (low pressure: n = 16; high pressure: n = 15) was undertaken. At 60 minutes, the high pressure group had greater mean partial pressure of arterial CO 2 (64 vs 50 mm Hg, P = .003) and end-tidal CO 2 (54 vs 45 mm Hg, P = .008) and a lesser pH (7.21 vs 7.29, P = .0005). There were no significant differences in base excess, peak airway pressure, operative time, or duration of hospital stay. Clinically indicated protocol breaches were more common in the low pressure than the high pressure group (8 vs 3, P = .03). In posterior retroperitoneoscopic adrenalectomy, greater insufflation pressures are associated with greater partial pressure of arterial CO 2 and end-tidal CO 2 and lesser pH at 60 minutes, be significant. Commencing with lesser CO 2 insufflation pressures decreases intraoperative acidosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Efficient absorption of SO2 with low-partial pressures by environmentally benign functional deep eutectic solvents.

PubMed

Zhang, Kai; Ren, Shuhang; Hou, Yucui; Wu, Weize

2017-02-15

Sulfur dioxide (SO 2 ) emitted from the burning of fossil fuels is one of the main air contaminants. In this work, we found that environmentally benign solvents, deep eutectic solvents (DESs) could be designed with a function to absorb low-partial pressure SO 2 from simulated flue gas. Two kinds of biodegradable functional DESs based on betaine (Bet) and l-carnitine (L-car) as hydrogen bond accepters (HBA) and ethylene glycol (EG) as a hydrogen bond donor (HBD) were prepared with mole ratios of HBA to HBD from 1:3 to 1:5, and they were investigated to absorb SO 2 with different partial pressures at various temperatures. The results showed that the two DESs could absorb low-partial pressure SO 2 efficiently. SO 2 absorption capacities of the DESs with HBA/HBD mole ratio of 1:3 were 0.332mol SO 2 /mol HBA for Bet+EG DES and 0.820mol SO 2 /mol HBA for L-car+EG DES at 40°C with a SO 2 partial pressure of 0.02atm. In addition, the regeneration experiments demonstrated that the absorption capacities of DESs did not change after five absorption and desorption cycles. Furthermore, the absorption mechanism of SO 2 by DESs was studied by FT-IR, 1 H NMR and 13 C NMR spectra. It was found that there are strong acid-base interactions between SO 2 and -COO - on HBA. Copyright © 2016 Elsevier B.V. All rights reserved.

Increased transcutaneous oxygen tension in the skin dorsum over the foot in patients with diabetic foot disease in response to the topical use of an emulsion of hyperoxygenated Fatty acids.

PubMed

Lázaro-Martínez, J L; Sánchez-Ríos, J P; García-Morales, E; Cecilia-Matilla, A; Segovia-Gómez, T

2009-12-01

The aim of this study was to examine changes in the skin over the feet of patients with diabetic foot syndrome after local application of a product containing hyperoxygenated fatty acids (HOFAs) by measuring transcutaneous oxygen. In 64 patients, transcutaneous oxygen pressure (TcPo(2)) was measured on days 0, 7, 30, 60, and 90 of the study. Foot skin dryness, shedding, and skin color were also assessed using a clinical score. The patients were grouped on the basis of initial levels of transcutaneous oxygen; group 1 comprised patients with TcPo( 2) >30 mm Hg and group 2 comprised patients with TcPo(2) <30 mm Hg on the skin over the dorsum of the feet. Increases in local oxygenation values were observed at a local level in group 2 patients after 30 days of treatment. Skin trophism showed clinical improvement in all patients and these observations may be attributed to improved local microcirculation.

Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen.

PubMed

Buchheit, R G; Schreiner, H R; Doebbler, G F

1966-02-01

Buchheit, R. G. (Union Carbide Corp., Tonawanda, N.Y.), H. R. Schreiner, and G. F. Doebbler. Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen. J. Bacteriol. 91:622-627. 1966.-Growth rate of the fungus Neurospora crassa depends in part on the nature of metabolically "inert gas" present in its environment. At high partial pressures, the noble gas elements (helium, neon, argon, krypton, and xenon) inhibit growth in the order: Xe > Kr> Ar > Ne > He. Nitrogen (N(2)) closely resembles He in inhibitory effectiveness. Partial pressures required for 50% inhibition of growth were: Xe (0.8 atm), Kr (1.6 atm), Ar (3.8 atm), Ne (35 atm), and He ( approximately 300 atm). With respect to inhibition of growth, the noble gases and N(2) differ qualitatively and quantitatively from the order of effectiveness found with other biological effects, i.e., narcosis, inhibition of insect development, depression of O(2)-dependent radiation sensitivity, and effects on tissue-slice glycolysis and respiration. Partial pressures giving 50% inhibition of N. crassa growth parallel various physical properties (i.e., solubilities, solubility ratios, etc.) of the noble gases. Linear correlation of 50% inhibition pressures to the polarizability and of the logarithm of pressure to the first and second ionization potentials suggests the involvement of weak intermolecular interactions or charge-transfer in the biological activity of the noble gases.

Measurement of alveolar oxygen partial pressure in the rat lung using Carr-Purcell-Meiboom-Gill spin-spin relaxation times of hyperpolarized 3He and 129Xe at 74 mT.

PubMed

Kraayvanger, Ryan J; Bidinosti, Christopher P; Dominguez-Viqueira, William; Parra-Robles, Juan; Fox, Matthew; Lam, Wilfred W; Santyr, Giles E

2010-11-01

Regional measurement of alveolar oxygen partial pressure can be obtained from the relaxation rates of hyperpolarized noble gases, (3) He and (129) Xe, in the lungs. Recently, it has been demonstrated that measurements of alveolar oxygen partial pressure can be obtained using the spin-spin relaxation rate (R(2) ) of (3) He at low magnetic field strengths (<0.1 T) in vivo. R(2) measurements can be achieved efficiently using the Carr-Purcell-Meiboom-Gill pulse sequence. In this work, alveolar oxygen partial pressure measurements based on Carr-Purcell-Meiboom-Gill R(2) values of hyperpolarized (3) He and (129) Xe in vitro and in vivo in the rat lung at low magnetic field strength (74 mT) are presented. In vitro spin-spin relaxivity constants for (3) He and (129) Xe were determined to be (5.2 ± 0.6) × 10(-6) Pa(-1) sec(-1) and (7.3 ± 0.4) × 10(-6) Pa(-1) s(-1) compared with spin-lattice relaxivity constants of (4.0 ± 0.4) × 10(-6) Pa(-1) s(-1) and (4.3 ± 1.3) × 10(-6) Pa(-1) s(-1), respectively. In vivo experimental measurements of alveolar oxygen partial pressure using (3) He in whole rat lung show good agreement (r(2) = 0.973) with predictions based on lung volumes and ventilation parameters. For (129) Xe, multicomponent relaxation was observed with one component exhibiting an increase in R(2) with decreasing alveolar oxygen partial pressure. Copyright © 2010 Wiley-Liss, Inc.

Temperature dependence of single-crystal elastic constants of flux-grown alpha-GaPO(4).

PubMed

Armand, P; Beaurain, M; Rufflé, B; Menaert, B; Papet, P

2009-06-01

The lattice parameter change with respect to temperature (T) has been measured using high-temperature powder X-ray diffraction techniques for high-temperature flux-grown GaPO(4) single crystals with the alpha-quartz structure. The lattice and the volume linear thermal expansion coefficients in the temperature range 303-1173 K were computed from the X-ray data. The percentage linear thermal expansions along the a and c axes at 1173 K are 1.5 and 0.51, respectively. The temperature dependence of the mass density rho of flux-grown GaPO(4) single crystals was evaluated using the volume thermal expansion coefficient alpha(V)(T) = 3.291 x 10(-5) - 2.786 x 10(-8) [T] + 4.598 x 10(-11)[T](2). Single-crystal high-resolution Brillouin spectroscopy measurements have been carried out at ambient pressure from 303 to 1123 K to determine the elastic constants C(IJ) of high-temperature flux-grown GaPO(4) material. The single-crystal elastic moduli were calculated using the sound velocities via the measured Brillouin frequency shifts Deltanu(B). These are, to our knowledge, the highest temperatures at which single-crystal elastic constants of alpha-GaPO(4) have been measured. Most of the room-temperature elastic constant values measured on flux-grown GaPO(4) material are higher than the ones found for hydrothermally grown GaPO(4) single crystals. The fourth-order temperature coefficients of both the Brillouin frequency shifts T(nuB)((n)) and the single-crystal elastic moduli T(C(IJ))((n)) were obtained. The first-order temperature coefficients of the C(IJ) are in excellent agreement with previous reports on low-temperature hydrothermally grown alpha-GaPO(4) single crystals, while small discrepancies in the higher-order temperature coefficients are observed. This is explained in terms of the OH content in the GaPO(4) network, which is an important parameter in the crystal thermal behavior.

A comparison of the pharmacokinetic and pharmacodynamic properties of nitroglycerin according to the composition of the administration set: A preliminary study.

PubMed

Kim, Choon Ok; Song, Jeongyun; Min, Ji Young; Park, Su Jung; Lee, Hye Mi; Byon, Hyo-Jin

2018-03-01

There is a risk of drug sorption into an intravenous administration set composed of polyvinyl chloride (PVC), polyurethane (PU), or polyolefin (PO). This has implications on the dose of the active ingredient the patient receives, and thus therapeutic success. This study aimed to determine the plasma concentration of nitroglycerin and the effect of nitroglycerin on patients based on the composition of the administration set. Using a randomized, open-labeled, 3 × 3 crossover method, 9 volunteers were assigned to 3 groups. In period I, nitroglycerin (100 μg/mL) was infused via a PVC- (group A), PU- (group B), or PO-based (group C) administration set. In period II, PU- (group A), PO- (group B), and PVC-based (group C) administration sets were used, and in period III, PO- (group A), PVC- (group B), and PU-based (group C) administration sets were used. The rate of drug administration in all periods was 12 mL/hour for 30 minutes using an infusion pump. Blood samples were collected, and the plasma concentrations of nitroglycerin were analyzed using validated high-performance liquid chromatography coupled with tandem mass spectrometry. Blood pressure was determined using a sphygmomanometer applied to the other upper arm at an interval of 5 minutes. We observed that the mean plasma concentration of nitroglycerin over time when administered using a PO-based tube was higher than that when using a PU- or PVC-based tube. When the percent change of the mean arterial pressure from baseline at each time point was compared among groups, there were statistically significant differences between PU and PO or PVC at most points during nitroglycerin infusion. Our results showed higher nitroglycerin plasma concentration and lower arterial pressure when a PO-based administration set was used than when a PVC- or PU-based administration set was used. PO-based administration sets may be more appropriate for nitroglycerin administration compared to those composed of PVC or PU.

A comparison of the pharmacokinetic and pharmacodynamic properties of nitroglycerin according to the composition of the administration set

PubMed Central

Kim, Choon Ok; Song, Jeongyun; Min, Ji Young; Park, Su Jung; Lee, Hye Mi; Byon, Hyo-Jin

2018-01-01

Abstract Background: There is a risk of drug sorption into an intravenous administration set composed of polyvinyl chloride (PVC), polyurethane (PU), or polyolefin (PO). This has implications on the dose of the active ingredient the patient receives, and thus therapeutic success. This study aimed to determine the plasma concentration of nitroglycerin and the effect of nitroglycerin on patients based on the composition of the administration set. Methods: Using a randomized, open-labeled, 3 × 3 crossover method, 9 volunteers were assigned to 3 groups. In period I, nitroglycerin (100 μg/mL) was infused via a PVC- (group A), PU- (group B), or PO-based (group C) administration set. In period II, PU- (group A), PO- (group B), and PVC-based (group C) administration sets were used, and in period III, PO- (group A), PVC- (group B), and PU-based (group C) administration sets were used. The rate of drug administration in all periods was 12 mL/hour for 30 minutes using an infusion pump. Blood samples were collected, and the plasma concentrations of nitroglycerin were analyzed using validated high-performance liquid chromatography coupled with tandem mass spectrometry. Blood pressure was determined using a sphygmomanometer applied to the other upper arm at an interval of 5 minutes. Results: We observed that the mean plasma concentration of nitroglycerin over time when administered using a PO-based tube was higher than that when using a PU- or PVC-based tube. When the percent change of the mean arterial pressure from baseline at each time point was compared among groups, there were statistically significant differences between PU and PO or PVC at most points during nitroglycerin infusion. Conclusion: Our results showed higher nitroglycerin plasma concentration and lower arterial pressure when a PO-based administration set was used than when a PVC- or PU-based administration set was used. PO-based administration sets may be more appropriate for nitroglycerin administration compared to those composed of PVC or PU. PMID:29489681

Mechanisms of Renal Phosphate Loss in Liver Resection-Associated Hypophosphatemia

PubMed Central

Nafidi, Otmane; Lapointe, Real W.; Lepage, Raymond; Kumar, Rajiv; D’Amour, Pierre

2014-01-01

Objective To determine precisely the role of parathyroid hormone (PTH) and of phosphatonins in the genesis of posthepatectomy hypophosphatemia. Background Posthepatectomy hypophosphatemia has recently been related to increased renal fractional excretion of phosphate (FE P). To address the cause of hypophosphatemia, we measured serum concentrations of PTH, various phosphatonins, and the number of removed hepatic segment in patients with this disorder. Methods Serum phosphate (PO4), ionized calcium (Ca++), HCO3−, pH and FE P, intact PTH (I-PTH), carboxyl-terminal fibroblast growth factor 23 (C-FGF-23) and intact fibroblast growth factor 23 (I-FGF-23), FGF-7, and secreted frizzled related-protein-4 (sFRP-4) were measured before and on postoperative (po) days 1, 2, 3, 5, and 7, in 18 patients undergoing liver resection. The number of removed hepatic segments was also assessed. Results Serum PO4 concentrations decreased within 24 hours, were lowest (0.66 ± 0.03 mmol/L; P < 0.001) at 48 hours, and returned to normal within 5 days of the procedure. FE P peaked at 25.07% ± 2.26% on po day 1 (P < 0.05). Decreased ionized calcium concentrations (1.10 ± 0.01 mmol/L; P < 0.01) were observed on po day 1 and were negatively correlated with increased I-PTH concentrations (8.8 ± 0.9 pmol/L; P < 0.01; correlation: r = −0.062, P = 0.016). FE P was positively related to I-PTH levels on po day 1 (r = 0.52, P = 0.047) and negatively related to PO4 concentrations (r = −0.56, P = 0.024). Severe hypophosphatemia and increased urinary phosphate excretion persisted for 72 hours even when I-PTH concentrations had returned to normal. I-FGF-23 decreased to its nadir of 7.8 ± 6.9 pg/mL (P < 0.001) on po day 3 and was correlated with PO4 levels on po days 0, 3, 5, and 7 (P < 0.001). C-FGF-23, FGF-7 and sFRP-4 levels could not be related to either PO4 concentrations or FE P. Conclusion Posthepatectomy hypophosphatemia is associated with increased FE P unrelated to I-FGF-23 or C-FGF-23, FGF-7, or sFRP-4. I-PTH contributes to excessive FE P partially on po day 1 but not thereafter. Other yet defined factors should explain post hepatectomy hypophosphatemia. PMID:19387319

Microvascular oxygen pressures in muscles comprised of different fiber types: Impact of dietary nitrate supplementation.

PubMed

Ferguson, Scott K; Holdsworth, Clark T; Wright, Jennifer L; Fees, Alex J; Allen, Jason D; Jones, Andrew M; Musch, Timothy I; Poole, David C

2015-08-01

Nitrate (NO3(-)) supplementation via beetroot juice (BR) preferentially improves vascular conductance and O2 delivery to contracting skeletal muscles comprised predominantly of type IIb + d/x (i.e. highly glycolytic) fibers following its reduction to nitrite and nitric oxide (NO). To address the mechanistic basis for NO3(-) to improve metabolic control we tested the hypothesis that BR supplementation would elevate microvascular PO2 (PO2mv) in fast twitch but not slow twitch muscle. Twelve young adult male Sprague-Dawley rats were administered BR ([NO3(-)] 1 mmol/kg/day, n = 6) or water (control, n = 6) for 5 days. PO2mv (phosphorescence quenching) was measured at rest and during 180 s of electrically-induced 1-Hz twitch contractions (6-8 V) of the soleus (9% type IIb +d/x) and mixed portion of the gastrocnemius (MG, 91% type IIb + d/x) muscles. In the MG, but not the soleus, BR elevated contracting steady state PO2mv by ~43% (control: 14 ± 1, BR: 19 ± 2 mmHg (P < 0.05)). This higher PO2mv represents a greater blood-myocyte O2 driving force during muscle contractions thus providing a potential mechanism by which NO3(-) supplementation via BR improves metabolic control in fast twitch muscle. Recruitment of higher order type II muscle fibers is thought to play a role in the development of the VO2 slow component which is inextricably linked to the fatigue process. These data therefore provide a putative mechanism for the BR-induced improvements in high-intensity exercise performance seen in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

Crayfish respiration as a function of water oxygenation.

PubMed

Dejours, P; Beekenkamp, H

1977-06-01

Crayfish, Astacus leptodactylus, for several hours breathed water equilibrated either with a hypoxic gas mixture, or air, or oxygen. The hydrostatic pressure in the right epibranchial cavity was recorded and the left epibranchial water sempled from time to time. The higher the water oxygenation, the less the duration of ventilation, the frequency of the scaphognathite beats which ensure water convection, the negative of the water hydrostatic pressure relative to ambient water pressure, and the respired water flow. The water convection per unit quantity of oxygen consumed decreased by a factor of about 20 when the animal passed from hypoxic water at PO2 of 72 torr to hyperoxic water at PO2 of 697 torr. Prolonged hyperoxia, up to 100 days, results in a hypercapnic acidosis of the prebranchial blood. pH decreased about 0.2 unit, PCO2 increased from 2.5 torr to a value of 6 torr, and [HCO-3] from 6 to a value of 9 meq-L-1. This hypercapnic acidosis remained uncompensated during several weeks exposure to hyperoxia. Observations on the fresh water crayfish, a marine crab, and several species of fish, suggest that in aquatic animals (1) the ventilatory activity depends greatly on the degree of water oxygenation: the higher the water oxygenation, the lower the ventilation; (2) the change of ventilation may be accompanied by a new equilibrium of the blood acid-base status, quite different from that observed in normoxia.

Racial differences in ocular oxidative metabolism: implications for ocular disease.

PubMed

Siegfried, Carla J; Shui, Ying-Bo; Holekamp, Nancy M; Bai, Fang; Beebe, David C

2011-07-01

To compare the Po(2) distribution in different regions in the eyes of patients undergoing intraocular surgery. Before initiation of intraocular cataract and/or glaucoma surgery, an optical oxygen sensor was introduced into the anterior chamber via a peripheral corneal paracentesis. The tip of the flexible fiberoptic probe was positioned by the surgeon for 3 measurements in all patients: (1) near the central corneal endothelium, (2) in the mid-anterior chamber, and (3) in the anterior chamber angle. In patients scheduled to undergo cataract extraction, Po(2) was also measured (4) at the anterior lens surface and (5) in the posterior chamber just behind the iris. Oxygen measurements at the 5 locations were compared using a 2-tailed unpaired t test and multivariate regression. The Po(2) value was significantly higher in African American patients at all 5 locations compared with Caucasian patients. Adjusting for age increased the significance of this association. Adjusting for race revealed that age was associated with increased Po(2) beneath the central cornea. Racial differences in oxygen levels in the human eye reflect an important difference in oxidative metabolism in the cornea and lens and may reflect differences in systemic physiologic function. Increased oxygen or oxygen metabolites may increase oxidative stress, cell damage, intraocular pressure, and the risk of developing glaucoma. Oxygen use by the cornea decreases with age.

Geometry of α-Cr2O3(0001) as a Function of H2O Partial Pressure

PubMed Central

2015-01-01

Surface X-ray diffraction has been employed to elucidate the surface structure of α-Cr2O3(0001) as a function of water partial pressure at room temperature. In ultra high vacuum, following exposure to ∼2000 Langmuir of H2O, the surface is found to be terminated by a partially occupied double layer of chromium atoms. No evidence of adsorbed OH/H2O is found, which is likely due to either adsorption at minority sites, or X-ray induced desorption. At a water partial pressure of ∼30 mbar, a single OH/H2O species is found to be bound atop each surface Cr atom. This adsorption geometry does not agree with that predicted by ab initio calculations, which may be a result of some differences between the experimental conditions and those modeled. PMID:26877825

The oxygen status algorithm: a computer program for calculating and displaying pH and blood gas data.

PubMed

Siggaard-Andersen, O; Siggaard-Andersen, M

1990-01-01

Input parameters for the program are the arterial pH, pCO2, and pO2 (measured by a blood gas analyzer), oxygen saturation, carboxy-, met-, and total hemoglobin (measured by a multi-wavelength spectrometer), supplemented by patient age, sex, temperature, inspired oxygen fraction, fraction of fetal hemoglobin, and ambient pressure. Output parameters are the inspired and alveolar oxygen partial pressures, pH,pCO2 and pO2 referring to the actual patient temperature, estimated shunt fraction, half-saturation tension, estimated 2,3-diphosphoglycerate concentration, oxygen content and oxygen capacity, extracellular base excess, and plasma bicarbonate concentration. Three parameters related to the blood oxygen availability are calculated: the oxygen extraction tension, concentration of extractable oxygen, and oxygen compensation factor. Calculations of the 'reverse' type may also be performed so that the effect of therapeutic measures on the oxygen status or the acid-base status can be predicted. The user may choose among several different units of measurement and two different conventions for symbols. The results are presented in a data display screen comprising all quantities together with age, sex, and temperature adjusted reference values. The program generates a 'laboratory diagnosis' of the oxygen status and the acid-base status and three graphs illustrating the oxygen status and the acid-base status of the patient: the oxygen graph, the acid-base chart and the blood gas map. A printed summary in one A4 page including a graphical display can be produced with an Epson or HP Laser compatible printer. The program is primarily intended for routine laboratories with a blood gas analyzer combined with a multi-wavelength spectrometer. Calculating the derived quantities may enhance the usefulness of the analyzers and improve patient care. The program may also be used as a teaching aid in acid-base and respiratory physiology. The program requires an IBM PC, XT, AT or similar compatible computer running under DOS version 2.11 or later. A VGA color monitor is preferred, but the program also supports EGA, CGA, and Hercules monitors. The program will be freely available at the cost of a discette and mailing expenses by courtesy of Radiometer Medical A/S, Emdrupvej 72, DK-2400 Copenhagen NV, Denmark (valid through 1991). A simplified algorithm for a programmable pocket calculator avoiding iterative calculations is given as an Appendix.

Hyperglycemia Suppresses Calcium Phosphate-Induced Aneurysm Formation Through Inhibition of Macrophage Activation.

PubMed

Tanaka, Teruyoshi; Takei, Yuichiro; Yamanouchi, Dai

2016-03-28

The aim of this study was to elucidate aspects of diabetes mellitus-induced suppression of aneurysm. We hypothesized that high glucose suppresses aneurysm by inhibiting macrophage activation via activation of Nr1h2 (also known as liver X receptor β), recently characterized as a glucose-sensing nuclear receptor. Calcium phosphate (CaPO4)-induced aneurysm formation was significantly suppressed in the arterial wall in type 1 and 2 diabetic mice. A murine macrophage cell line, RAW264.7, was treated with tumor necrosis factor α (TNF-α) plus CaPO4 and showed a significant increase in matrix metalloproteinase 9 (Mmp9) mRNA and secreted protein expression compared with TNF-α alone. Elevated Mmp9 expression was significantly suppressed by hyperglycemic conditions (15.5 mmol/L glucose) compared with normoglycemic conditions (5.5 mmol/L glucose) or normoglycemic conditions with high osmotic pressure (5.5 mmol/L glucose +10.0 mmol/L mannitol). Nr1h2 mRNA and protein expression were suppressed by treatment with TNF-α plus CaPO4 but were restored by hyperglycemic conditions. Activation of Nr1h2 by the antagonist GW3965 during stimulation with TNF-α plus CaPO4 mimicked hyperglycemic conditions and inhibited Mmp9 upregulation, whereas the deactivation of Nr1h2 by small interfering RNA (siRNA) under hyperglycemic conditions canceled the suppressive effect and restored Mmp9 expression induced by TNF-α plus CaPO4. Moreover, Nr1h2 activation with GW3965 significantly suppressed CaPO4-induced aneurysm in mice compared with vehicle-injected control mice. Our results show that hyperglycemia suppresses macrophage activation and aneurysmal degeneration through the activation of Nr1h2. Although further validation of the underlying pathway is necessary, targeting Nr1h2 is a potential therapeutic approach to treating aneurysm. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Sulfur control in ion-conducting membrane systems

DOEpatents

Stein, VanEric Edward; Richards, Robin Edward; Brengel, David Douglas; Carolan, Michael Francis

2003-08-05

A method for controlling the sulfur dioxide partial pressure in a pressurized, heated, oxygen-containing gas mixture which is contacted with an ion-conducting metallic oxide membrane which permeates oxygen ions. The sulfur dioxide partial pressure in the oxygen-depleted non-permeate gas from the membrane module is maintained below a critical sulfur dioxide partial pressure, p.sub.SO2 *, to protect the membrane material from reacting with sulfur dioxide and reducing the oxygen flux of the membrane. Each ion-conducting metallic oxide material has a characteristic critical sulfur dioxide partial pressure which is useful in determining the required level of sulfur removal from the feed gas and/or from the fuel gas used in a direct-fired feed gas heater.

A Kinase-Independent Function of c-Src Mediates p130Cas Phosphorylation at the Serine-639 Site in Pressure Overloaded Myocardium.

PubMed

Palanisamy, Arun P; Suryakumar, Geetha; Panneerselvam, Kavin; Willey, Christopher D; Kuppuswamy, Dhandapani

2015-12-01

Early work in pressure overloaded (PO) myocardium shows that integrins mediate focal adhesion complex formation by recruiting the adaptor protein p130Cas (Cas) and nonreceptor tyrosine kinase c-Src. To explore c-Src role in Cas-associated changes during PO, we used a feline right ventricular in vivo PO model and a three-dimensional (3D) collagen-embedded adult cardiomyocyte in vitro model that utilizes a Gly-Arg-Gly-Asp-Ser (RGD) peptide for integrin stimulation. Cas showed slow electrophoretic mobility (band-shifting), recruitment to the cytoskeleton, and tyrosine phosphorylation at 165, 249, and 410 sites in both 48 h PO myocardium and 1 h RGD-stimulated cardiomyocytes. Adenoviral mediated expression of kinase inactive (negative) c-Src mutant with intact scaffold domains (KN-Src) in cardiomyocytes did not block the RGD stimulated changes in Cas. Furthermore, expression of KN-Src or kinase active c-Src mutant with intact scaffold function (A-Src) in two-dimensionally (2D) cultured cardiomyocytes was sufficient to cause Cas band-shifting, although tyrosine phosphorylation required A-Src. These data indicate that c-Src's adaptor function, but not its kinase function, is required for a serine/threonine specific phosphorylation(s) responsible for Cas band-shifting. To explore this possibility, Chinese hamster ovary cells that stably express Cas were infected with either β-gal or KN-Src adenoviruses and used for Cas immunoprecipitation combined with mass spectrometry analysis. In the KN-Src expressing cells, Cas showed phosphorylation at the serine-639 (human numbering) site. A polyclonal antibody raised against phospho-serine-639 detected Cas phosphorylation in 24-48 h PO myocardium. Our studies indicate that c-Src's adaptor function mediates serine-639 phosphorylation of Cas during integrin activation in PO myocardium. © 2015 Wiley Periodicals, Inc.

Free-radical probes for functional in vivo EPR imaging

NASA Astrophysics Data System (ADS)

Subramanian, S.; Krishna, M. C.

2007-02-01

Electron paramagnetic resonance imaging (EPRI) is one of the recent functional imaging modalities that can provide valuable in vivo physiological information on its own merit and aids as a complimentary imaging technique to MRI and PET of tissues especially with respect to in vivo pO II (oxygen partial pressure), redox status and pharmacology. EPR imaging mainly deals with the measurement of distribution and in vivo dynamics and redox changes using special nontoxic paramagnetic spin probes that can be infused into the object of investigation. These spin probes should be characterized by simple EPR spectra, preferably with narrow EPR lines. The line width should be reversibly sensitive to the concentration of in vivo pO II with a linear dependence. Several non-toxic paramagnetic probes, some particulate and insoluble and others water-soluble and infusible (by intravenous or intramuscular injection) have been developed which can be effectively used to quantitatively assess tissue redox status, and tumor hypoxia. Quantitative assessment of the redox status of tissue in vivo is important in investigating oxidative stress, and that of tissue pO II is very important in radiation oncology. Other areas in which EPR imaging and oxymetry may help are in the investigation of tumorangiogenesis, wound healing, oxygenation of tumor tissue by the ingestion of oxygen-rich gases, etc. The correct choice of the spin probe will depend on the modality of measurement (whether by CW or time-domain EPR imaging) and the particular physiology interrogated. Examples of the available spin probes and some EPR imaging applications employing them are presented.

Cardiorespiratory responses of the facultative air-breathing fish jeju, Hoplerythrinus unitaeniatus (Teleostei, Erythrinidae), exposed to graded ambient hypoxia.

PubMed

Oliveira, R D; Lopes, J M; Sanches, J R; Kalinin, A L; Glass, M L; Rantin, F T

2004-12-01

The jeju, Hoplerythrinus unitaeniatus, is equipped with a modified part of the swim bladder that allows aerial respiration. On this background, we have evaluated its respiratory and cardiovascular responses to aquatic hypoxia. Its aquatic O2 uptake (V(O2)) was maintained constant down to a critical P(O2) (P(cO2)) of 40 mm Hg, below which V(O2) declined linearly with further reductions of P(iO2). Just below P(cO2), the ventilatory tidal volume (V(T)) increased significantly along with gill ventilation (V(G)), while respiratory frequency changed little. Consequently, water convection requirement (V(G)/V(O2)) increased steeply. The same threshold applied to cardiovascular responses that included reflex bradycardia and elevated arterial blood pressure (P(a)). Aerial respiration was initiated at water P(O2) of 44 mm Hg and breathing episodes and time at the surface increased linearly with more severe hypoxia. At the lowest water P(O2) (20 mm Hg), the time spent at the surface accounted for 50% of total time. This response has a character of a temporary emergency behavior that may allow the animal to escape hypoxia.

Microvascular oxygen pressures in muscles comprised of different fiber types: Impact of dietary nitrate supplementation

PubMed Central

Ferguson, Scott K.; Holdsworth, Clark T.; Wright, Jennifer L.; Fees, Alex J.; Allen, Jason D.; Jones, Andrew M.; Musch, Timothy I.; Poole, David C.

2014-01-01

Nitrate (NO3−) supplementation via beetroot juice (BR) preferentially improves vascular conductance and O2 delivery to contracting skeletal muscles comprised predominantly of type IIb + d/x (i.e. highly glycolytic) fibers following its reduction to nitrite and nitric oxide (NO). To address the mechanistic basis for NO3− to improve metabolic control we tested the hypothesis that increased NO bioavailability via BR supplementation would elevate microvascular PO2 (PO2mv) in fast twitch but not slow twitch muscle. Twelve young adult male Sprague-Dawley rats were administered BR ([NO3−] 1 mmol/kg/day, n=6) or water (control, n=6) for 5 days. PO2mv (phosphorescence quenching) was measured at rest and during 180s of electrically induced 1-Hz twitch contractions (6–8 V) of the soleus (9% type IIb +d/x) and mixed portion of the gastrocnemius (MG, 91% type IIb + d/x) muscles. In the MG, but not the soleus, BR elevated contracting steady state PO2mv by ~43% (control: 13.7 ± 0.5, BR: 19 ± 1.6 mmHg, (P<0.05). This higher PO2mv represents a greater blood-myocyte O2 driving force during muscle contractions thus providing a potential mechanism by which NO3− supplementation via BR improves metabolic control in fast twitch muscle. Recruitment of higher order type II muscle fibers is thought to play a role in the development of the V.O2 slow component which is inextricably linked to the fatigue process. These data therefore provide a putative mechanism for the BR-induced improvements in high-intensity exercise performance seen in humans. PMID:25280991

Localized increase of tissue oxygen tension by magnetic targeted drug delivery

NASA Astrophysics Data System (ADS)

Liong, Celine; Ortiz, Daniel; Ao-ieong, Eilleen; Navati, Mahantesh S.; Friedman, Joel M.; Cabrales, Pedro

2014-07-01

Hypoxia is the major hindrance to successful radiation therapy of tumors. Attempts to increase the oxygen (O2) tension (PO2) of tissue by delivering more O2 have been clinically disappointing, largely due to the way O2 is transported and released by the hemoglobin (Hb) within the red blood cells (RBCs). Systemic manipulation of O2 transport increases vascular resistance due to metabolic autoregulation of blood flow to prevent over oxygenation. This study investigates a new technology to increase O2 delivery to a target tissue by decreasing the Hb-O2 affinity of the blood circulating within the targeted tissue. As the Hb-O2 affinity decreases, the tissue PO2 to satisfy tissue O2 metabolic needs increases without increasing O2 delivery or extraction. Paramagnetic nanoparticles (PMNPs), synthetized using gadolinium oxide, were coated with the cell permeable Hb allosteric effector L35 (3,5-trichlorophenylureido-phenoxy-methylpropionic acid). L35 decreases Hb affinity for O2 and favors the release of O2. The L35-coated PMNPs (L35-PMNPs) were intravenously infused (10 mg kg-1) to hamsters instrumented with the dorsal window chamber model. A magnetic field of 3 mT was applied to localize the effects of the L35-PMNPs to the window chamber. Systemic O2 transport characteristics and microvascular tissue oxygenation were measured after administration of L35-PMNPs with and without magnetic field. The tissue PO2 in untreated control animals was 25.2 mmHg. L35-PMNPs without magnetic field decreased tissue PO2 to 23.4 mmHg, increased blood pressure, and reduced blood flow, largely due to systemic modification of Hb-O2 affinity. L35-PMNPs with magnetic field increased tissue PO2 to 27.9 mmHg, without systemic or microhemodynamic changes. These results indicate that localized modification of Hb-O2 affinity can increase PO2 of target tissue without affecting systemic O2 delivery or triggering O2 autoregulation mechanisms. This technology can be used to treat local hypoxia and to increase O2 in tumors, enhancing the efficacy of radiation therapies.

Spatial and Temporal Variations in the Partial Pressure and Emission of CO2 and CH4 in and Amazon Floodplain Lake

NASA Astrophysics Data System (ADS)

Forsberg, B. R.; Amaral, J. H.; Barbosa, P.; Kasper, D.; MacIntyre, S.; Cortes, A.; Sarmento, H.; Borges, A. V.; Melack, J. M.; Farjalla, V.

2015-12-01

The Amazon floodplain contains a variety of wetland environments which contribute CO2 and CH4 to the regional and global atmospheres. The partial pressure and emission of these greenhouse gases (GHGs) varies: 1) between habitats, 2) seasonally, as the characteristics these habitats changes and 3) diurnally, in response to diurnal stratification. In this study, we investigated the combined influence of these factors on the partial pressure and emission of GHGs in Lago Janauacá, a central Amazon floodplain lake (3o23' S; 60o18' O). All measurements were made between August of 2014 and April of 2015 at two different sites and in three distinct habitats: open water, flooded forest, flooded macrophytes. Concentrations of CO2 and CH4 in air were measured continuously with a cavity enhanced absorption spectrometer, Los Gatos Research´s Ultraportable Greenhouse Gas Analyzer (UGGA). Vertical profiles o pCO2 and pCH4 were measured using the UGGA connected to an electric pump and equilibrator. Diffusive surface emissions were estimated with the UGGA connected to a static floating chamber. To investigate the influence of vertical stratification and mixing on GHG partial pressure and emissions, a meteorological station and submersible sensor chain were deployed at each site. Meteorological sensors included wind speed and direction. The submersible chains included thermistors and oxygen sensors. Depth profiles of partial pressure and diffusive emissions for both CO2 and CH4 varied diurnally, seasonally and between habitats. Both pCO2 and pCH4 were consistently higher in bottom than surface waters with the largest differences occurring at high water when thermal stratification was most stable. Methane emissions and partial pressures were highest at low water while pCO2 and CO2 fluxes were highest during high water periods, with 35% of CO2 fluxes at low water being negative. The highest average surface value of pCO2 (5491 μatm), encountered during rising water, was ~3 times higher than that encountered at low water (1708 μatm). Partial pressures and emissions of both CO2 and CH4 were greatest in open water habitats and consistently higher at night. These patterns reflected the higher levels of wind driven mixing and turbulence in open water environments and higher convective mixing at night which promoted diffusive emission.

Oxygen vacancy induced phase formation and room temperature ferromagnetism in undoped and Co-doped TiO2 thin films

NASA Astrophysics Data System (ADS)

Mohanty, P.; Mishra, N. C.; Choudhary, R. J.; Banerjee, A.; Shripathi, T.; Lalla, N. P.; Annapoorni, S.; Rath, Chandana

2012-08-01

TiO2 and Co-doped TiO2 (CTO) thin films deposited at various oxygen partial pressures by pulsed laser deposition exhibit room temperature ferromagnetism (RTFM) independent of their phase. Films deposited at 0.1 mTorr oxygen partial pressure show a complete rutile phase confirmed from glancing angle x-ray diffraction and Raman spectroscopy. At the highest oxygen partial pressure, i.e. 300 mTorr, although the TiO2 film shows a complete anatase phase, a small peak corresponding to the rutile phase along with the anatase phase is identified in the case of CTO film. An increase in O to Ti/(Ti+Co) ratio with increase in oxygen partial pressure is observed from Rutherford backscattering spectroscopy. It is revealed from x-ray photoelectron spectroscopy (XPS) that oxygen vacancies are found to be higher in the CTO film than TiO2, while the valency of cobalt remains in the +2 state. Therefore, the CTO film deposited at 300 mTorr does not show a complete anatase phase unlike the TiO2 film deposited at the same partial pressure. We conclude that RTFM in both films is not due to impurities/contaminants, as confirmed from XPS depth profiling and cross-sectional transmission electron microscopy (TEM), but due to oxygen vacancies. The magnitude of moment, however, depends not only on the phase of TiO2 but also on the crystallinity of the films.

Simultaneous measurement of pulmonary diffusing capacity for carbon monoxide and nitric oxide.

PubMed

Yamaguchi, Kazuhiro; Tsuji, Takao; Aoshiba, Kazutetsu; Nakamura, Hiroyuki

2018-03-01

In Europe and America, the newly-developed, simultaneous measurement of diffusing capacity for CO (D LCO ) and NO (D LNO ) has replaced the classic D LCO measurement for detecting the pathophysiological abnormalities in the acinar regions. However, simultaneous measurement of D LCO and D LNO is currently not used by Japanese physicians. To encourage the use of D LNO in Japan, the authors reviewed aspects of simultaneously-estimated D LCO and D LNO from previously published manuscripts. The simultaneous D LCO -D LNO technique identifies the alveolocapillary membrane-related diffusing capacity (membrane component, D M ) and the blood volume in pulmonary microcirculation (V C ); V C is the principal factor constituting the blood component of diffusing capacity (D B ,D B =θ·V C where θ is the specific gas conductance for CO or NO in the blood). As the association velocity of NO with hemoglobin (Hb) is fast and the affinity of NO with Hb is high in comparison with those of CO, θ NO can be taken as an invariable simply determined by diffusion limitation inside the erythrocyte. This means that θ NO is independent of the partial pressure of oxygen (PO 2 ). However, θ CO involves the limitations by diffusion and chemical reaction elicited by the erythrocyte, resulting in θ CO to be a PO 2 -dependent variable. Furthermore, D LCO is determined primarily by D B (∼77%), while D LNO is determined equally by D M (∼55%) and D B (∼45%). This suggests that D LCO is more sensitive for detecting microvascular diseases, while D LNO can equally identify alveolocapillary membrane and microcirculatory abnormalities. Copyright © 2017 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Iron doped LiCoPO4 thin films for lithium-ion microbatteries obtained by ns pulsed laser deposition

NASA Astrophysics Data System (ADS)

Smaldone, A.; Brutti, S.; De Bonis, A.; Ciarfaglia, N.; Santagata, A.; Teghil, R.

2018-07-01

Well crystallized and homogeneous iron doped LiCoPO4 (LCfP) thin films have been grown by ns Pulsed Laser Ablation, at ambient temperature without any substrate heating or post-annealing treatments. The films have been deposited in vacuum and in the presence of buffer gases (O2, Ar) and it has been found that their crystallinity, structure and morphology depend on pressure conditions. The films have been studied by Scanning Electron Microscopy and X Ray Diffraction, while their first steps of growth have been characterized by Transmission Electron Microscopy. A study of the plasma produced by the laser ablation in the different pressure conditions has been carried out with the aim of elucidate the mechanisms involved in the films deposition. LCfP thin films have been also tested as microelectrodes in lithium cells in galvanostatic condition for analyzing the reversibility of the lithium-ion battery.

O 1s core levels in Bi2Sr2CaCu2O8+δ single crystals

NASA Astrophysics Data System (ADS)

Parmigiani, F.; Shen, Z. X.; Mitzi, D. B.; Lindau, I.; Spicer, W. E.; Kapitulnik, A.

1991-02-01

High-quality Bi2Sr2CaCu2O8+δ superconducting single crystals, annealed at different oxygen partial pressures, have been studied using angular-resolved x-ray photoelectron spectroscopy with a resolution higher than that used in any previous study. Two states of the oxygen, separated by ~=0.7 eV, are unambiguously observed. Examining these components at different angles makes it possible to distinguish bulk from surface components. Using this capability we discover that annealing under lower oxygen partial pressure (1 atm) results in oxygen intercalation beneath the Bi-O surface layer of the crystal, whereas for higher-pressure anneals (12 atm) additional oxygen is found on the Bi-O surfaces. This steplike intercalation mechanism is also confirmed by the changes observed in the Cu and Bi core lines as a function of the annealing oxygen partial pressure.

The effects of endothelin-1 on the cardiorespiratory physiology of the freshwater trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias).

PubMed

Perry, S F; Montpetit, C J; McKendry, J; Desforges, P R; Gilmour, K M; Wood, C M; Olson, K R

2001-11-01

The aim of the present study was to evaluate the effects of endothelin-l-elicited cardiovascular events on respiratory gas transfer in the freshwater rainbow trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias). In both species, endothelin-1 (666 pmol kg(-1)) caused a rapid (within 4 min) reduction (ca. 30-50 mmHg) in arterial blood partial pressure of O2. The effects of endothelin-1 on arterial blood partial pressure of CO2 were not synchronised with the changes in O2 partial pressure and the responses were markedly different in trout and dogfish. In trout, arterial CO2 partial pressure was increased transiently by approximately 1.0 mmHg but the onset of the response was delayed and occurred 12 min after endothelin-1 injection. In contrast, CO2 partial pressure remained more-or-less constant in dogfish after injection of endothelin-1 and was increased only slightly (approximately 0.1 mmHg) after 60 min. Pre-treatment of trout with bovine carbonic anhydrase (5 mg ml(-1)) eliminated the increase in CO2 partial pressure that was normally observed after endothelin-1 injection. In both species, endothelin-1 injection caused a decrease in arterial blood pH that mirrored the changes in CO2 partial pressure. Endothelin-1 injection was associated with transient (trout) or persistent (dogfish) hyperventilation as indicated by pronounced increases in breathing frequency and amplitude. In trout, arterial blood pressure remained constant or was decreased slightly and was accompanied by a transient increase in systemic resistance, and a temporary reduction in cardiac output. The decrease in cardiac output was caused solely by a reduction in cardiac frequency; cardiac stroke volume was unaffected. In dogfish, arterial blood pressure was lowered by approximately 10 mmHg at 6-10 min after endothelin-1 injection but then was rapidly restored to pre-injection levels. The decrease in arterial blood pressure reflected an increase in branchial vascular resistance (as determined using in situ perfused gill preparations) that was accompanied by simultaneous decreases in systemic resistance and cardiac output. Cardiac frequency and stroke volume were reduced by endothelin-1 injection and thus both variables contributed to the changes in cardiac output. We conclude that the net consequences of endothelin-1 on arterial blood gases result from the opposing effects of reduced gill functional surface area (caused by vasoconstriction) and an increase in blood residence time within the gill (caused by decreased cardiac output.

State-specific approach and computation of resonance states: Identification and properties of the lowest 2Po and 2D triply excited states of He-

NASA Astrophysics Data System (ADS)

Nicolaides, Cleanthes A.; Piangos, Nicos A.

2001-11-01

We discuss aspects of the theory and computation of resonance (autoionizing) states of polyelectronic atoms and their positive and negative ions, in the context of the state-specific approach, using as paradigms the He-2s22p 2Po and 2s2p2 2D triply excited states. The He- 2D resonance has been the subject of controversy about its nature and its very existence, with ramifications as to the physics of electron-He scattering measurements and as to the theory of resonance states in multiparticle systems in general. By carrying out a series of computations, we show how (quasi)localization of these resonances takes place. The results confirm the existence of the 2D resonance just below the energy of the He 2s2p 3Po resonance, with which it overlaps. The localization of the two He- resonances is achieved already at the single-configuration level, provided the orbitals are calculated by solving state-specific restricted Hartree-Fock (HF) equations. Accounting for orbital flexibility and relaxation due to the self-consistent interactions is essential to the achievement of a local energy minimum. The localized nature of the wavepacket is revealed even more definitely by solving appropriate multiconfigurational HF (MCHF) equations containing the information from the self-consistent interaction with closed channels as well as with the neighboring significant open ones. Reaching a reliable MCHF solution for a variety of polyelectronic multiply excited states may often be difficult, but once it is achieved it provides the overwhelmingly dominant characteristics of the state. It is then used as the reference wave function for computing variationally the remaining of the localized electron correlation in terms of optimized analytic orbitals representing very nearly the full space of the electron virtual excitations. The calculation of the localized part Ψ0 and of E0=<Ψ0/H/Ψ0>, is done by nonorthonormal configuration interaction (NONCI) since parts of Ψ0 are optimized separately in terms of their own basis sets. The final Ψ0s for the two resonances consisted of 683 symmetry-adapted configurations for the 2Po state and 778 ones for the 2D state. Using these functions and final state scattering functions with continuum orbitals obtained numerically in term-dependent core potentials, without and with polarization, of a number of lower-lying open channels, we employed the independent channel approximation and computed partial and total energy shifts and widths, the latter from energy-dependent golden rule expressions. Critical comparison of our results for E=E0+Δ, where Δ is the shift induced by the interaction of Ψ0 with the continuum, and for the width, Γ, with the existing few experimental and theoretical values, led us to the conclusion that the E and Γ lie in the following ranges: For the 2Po state: E=57.204+/-0.005 eV, Γ=68-74 meV, and for the 2D state: E=58.295+/-0.010 eV, Γ=38-55 meV. Of special theoretical and experimental interest is the determination of the partial and total widths of the three-electron He- 2D resonance, since it overlaps from below the two-electron threshold state He 2s2p 3Po, whose position is at 58.312 eV with a width of 8 meV.

Reproducing early Martian atmospheric carbon dioxide partial pressure by modeling the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops on Mars

NASA Astrophysics Data System (ADS)

Berk, Wolfgang; Fu, Yunjiao; Ilger, Jan-Michael

2012-10-01

The well defined composition of the Comanche rock's carbonate (Magnesite0.62Siderite0.25Calcite0.11Rhodochrosite0.02) and its host rock's composition, dominated by Mg-rich olivine, enable us to reproduce the atmospheric CO2partial pressure that may have triggered the formation of these carbonates. Hydrogeochemical one-dimensional transport modeling reveals that similar aqueous rock alteration conditions (including CO2partial pressure) may have led to the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops (Gusev Crater) and also in the ultramafic rocks exposed in the Nili Fossae region. Hydrogeochemical conditions enabling the formation of Mg-rich solid solution carbonate result from equilibrium species distributions involving (1) ultramafic rocks (ca. 32 wt% olivine; Fo0.72Fa0.28), (2) pure water, and (3) CO2partial pressures of ca. 0.5 to 2.0 bar at water-to-rock ratios of ca. 500 molH2O mol-1rock and ca. 5°C (278 K). Our modeled carbonate composition (Magnesite0.64Siderite0.28Calcite0.08) matches the measured composition of carbonates preserved in the Comanche rocks. Considerably different carbonate compositions are achieved at (1) higher temperature (85°C), (2) water-to-rock ratios considerably higher and lower than 500 mol mol-1 and (3) CO2partial pressures differing from 1.0 bar in the model set up. The Comanche rocks, hosting the carbonate, may have been subjected to long-lasting (>104 to 105 years) aqueous alteration processes triggered by atmospheric CO2partial pressures of ca. 1.0 bar at low temperature. Their outcrop may represent a fragment of the upper layers of an altered olivine-rich rock column, which is characterized by newly formed Mg-Fe-Ca solid solution carbonate, and phyllosilicate-rich alteration assemblages within deeper (unexposed) units.

Pb-210 and Po-210 atmospheric releases via fly ash from oil shale-fired power plants.

PubMed

Vaasma, Taavi; Loosaar, Jüri; Gyakwaa, Francis; Kiisk, Madis; Özden, Banu; Tkaczyk, Alan H

2017-03-01

During high temperature processes in the furnace volatile and semi-volatile elements and radionuclides are partially emitted to the environment, depending on their chemical form in the original fuel, the technological set-up of the combustion system, and the prevailing combustion conditions. Two of the world's largest oil shale-fired power plants (PPs) have been operational in Estonia from the 1960s, during which time creation of significant environmental emissions and waste containing naturally occurring radionuclides has occurred. Pb-210 and 210 Po are considered natural radionuclides with the highest emission rates from PPs and possess elevated potential radiation exposure risks to humans and the environment. These radionuclides have the highest activity concentration values in fine ash fractions, especially in fractions remaining below 2.5 μm. To determine the activity concentrations of 210 Pb and 210 Po in the PPs' outlet, sampling was conducted from boilers operating on pulverized fuel (PF) technology with novel integrated desulphurization (NID) system and bag filters as well as with electrostatic precipitators (ESPs). The 210 Pb and 210 Po activity concentrations remained around 300 Bq kg -1 for the NID system compared to 60-80 Bq kg -1 in the ESP system. The dominant ash fraction in both systems was PM2.5, constituting over 50% of the fly ash mass collected from the outlet. The authors estimate that the total atmospherically emitted activity for the modernized PPs remains dominantly below 1% of the activity that is inserted via fuel. The implementation of higher efficiency purifications systems has significantly reduced the negative effect of these PPs. Based on annually emitted fly ash and boilers' working hours, the 210 Pb and 210 Po activity released relative to energy production were up to 68.3 kBq GWh el -1 for 210 Pb and 64.6 kBq GWh el -1 for 210 Po. These values are 1 to 2 orders of magnitude lower compared to the situation in the 1980s. These findings represent the first publicly available quantitative results estimating the 210 Po emissions from large oil shale-fired PPs. Copyright © 2016 Elsevier Ltd. All rights reserved.

40 CFR 60.334 - Monitoring of operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... continuous monitoring system to monitor and record the fuel consumption and the ratio of water or steam to...) On a ppm basis (for NOX) and a percent O2 basis for oxygen; or (ii) On a ppm at 15 percent O2 basis... temperature (Ta), and minimum combustor inlet absolute pressure (Po) into the ISO correction equation. (iii...

40 CFR 60.334 - Monitoring of operations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... continuous monitoring system to monitor and record the fuel consumption and the ratio of water or steam to...) On a ppm basis (for NOX) and a percent O2 basis for oxygen; or (ii) On a ppm at 15 percent O2 basis... temperature (Ta), and minimum combustor inlet absolute pressure (Po) into the ISO correction equation. (iii...

40 CFR 60.334 - Monitoring of operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... continuous monitoring system to monitor and record the fuel consumption and the ratio of water or steam to...) On a ppm basis (for NOX) and a percent O2 basis for oxygen; or (ii) On a ppm at 15 percent O2 basis... temperature (Ta), and minimum combustor inlet absolute pressure (Po) into the ISO correction equation. (iii...

40 CFR 60.334 - Monitoring of operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... continuous monitoring system to monitor and record the fuel consumption and the ratio of water or steam to...) On a ppm basis (for NOX) and a percent O2 basis for oxygen; or (ii) On a ppm at 15 percent O2 basis... temperature (Ta), and minimum combustor inlet absolute pressure (Po) into the ISO correction equation. (iii...

40 CFR 60.334 - Monitoring of operations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... continuous monitoring system to monitor and record the fuel consumption and the ratio of water or steam to...) On a ppm basis (for NOX) and a percent O2 basis for oxygen; or (ii) On a ppm at 15 percent O2 basis... temperature (Ta), and minimum combustor inlet absolute pressure (Po) into the ISO correction equation. (iii...

Replacement of fish oil with palm oil: Effects on growth performance, innate immune response, antioxidant capacity and disease resistance in Nile tilapia (Oreochromis niloticus).

PubMed

Larbi Ayisi, Christian; Zhao, Jinliang; Wu, Jun-Wei

2018-01-01

This study was conducted to investigate the effects of replacing dietary fish oil (FO) with palm oil (PO) in juvenile Nile tilapia, Oreochromis niloticus (9.34± 0.02g initial weight) with emphasis on growth performance, digestive enzyme activities as well as serum biochemical parameters. Also, lysozyme activity (LYZ), respiratory burst (RB), superoxide dismutase (SOD), catalase (CAT) and resistance to Streptococcus iniae were investigated. Fish were stocked in 15 rectangular fiber glass tanks (150× 60× 40 cm) at 40 fish per tank with water maintained at 210 litres. Fish were fed five isonitrogenous (33% crude protein) and isolipidic (10% lipid) diets with PO included at 0% (0% PO), 25% (25% PO), 50% (50%PO), 75% (75% PO) and 100% (100% PO) for 8 weeks. The findings demonstrated that growth, and feed utilization was not compromised when PO was used in place of FO either partially or totally. Except for protease activity which was not significantly altered, lipase and amylase activities were significantly altered when FO was replaced with PO. There were no significant differences among treatments for CAT, SOD and LYZ. Serum malondialdehyde (MDA) in fish fed 100% PO was significantly lower than all other groups whiles total antioxidant capacity (TAC) of fish fed 0% PO was significantly higher than all other groups. Fish fed 0% PO, 25% PO and 50% PO had glutathione reductase (GR) significantly higher than fish fed 75% PO and 100% PO. RB in fish fed 0% PO were significantly lower than fish fed 75% PO and 100% PO. Also, fish fed 0% PO had significantly lower total protein (TP) compared with groups fed 50% PO and 75% PO. Fish fed diets with PO had similar resistance ability to Streptococcus iniae as those fed diets with FO. However, the liver function was likely to be compromised due to the increase in aspartate amino transferase (AST) and alkaline phosphatas (ALP) along increasing PO inclusion levels. AST, total protein, triacylglycerol (TAG) and low-density lipoprotein cholesterol (LDL-C) were significantly higher (p<0.05) in groups fed higher levels of PO. This study therefore concludes that feeding tilapia fingerlings with diets containing PO affects antioxidant and innate immune parameters negatively due to the reduction in LYS, TAC, GR, MDA, CAT, SOD and GSHpx.

Arterial blood gas reference values for sea level and an altitude of 1,400 meters.

PubMed

Crapo, R O; Jensen, R L; Hegewald, M; Tashkin, D P

1999-11-01

Blood gas measurements were collected on healthy lifetime nonsmokers at sea level (n = 96) and at an altitude of 1,400 meters (n = 243) to establish reference equations. At each study site, arterial blood samples were analyzed in duplicate on two separate blood gas analyzers and CO-oximeters. Arterial blood gas variables included Pa(O(2)), Pa(CO(2)), pH, and calculated alveolar-arterial PO(2) difference (AaPO(2)). CO-oximeter variables were Hb, COHb, MetHb, and Sa(O(2)). Subjects were 18 to 81 yr of age with 166 male and 173 female. Outlier data were excluded from multiple regression analysis, and reference equations were fitted to the data in two ways: (1) best fit using linear, squared, and cross-product terms; (2) simple equations, including only the variables that explained at least 3% of the variance. Two sets of equations were created: (1) using only the sea level data and (2) using the combined data with barometric pressure as an independent variable. Comparisons with earlier studies revealed small but significant differences; the decline in Pa(O(2)) with age at each altitude was consistent with most previous studies. At sea level, the equation that included barometric pressure predicted Pa(O(2)) slightly better than the sea level specific equation. The inclusion of barometric pressure in the equations allows better prediction of blood gas reference values at sea level and at altitudes as high as 1,400 meters.

Cardiopulmonary function after pulmonary contusion and partial liquid ventilation.

PubMed

Moomey, C B; Fabian, T C; Croce, M A; Melton, S M; Proctor, K G

1998-08-01

To compare the effects of mechanical ventilation with either positive end-expiratory pressure (PEEP) or partial liquid ventilation (PLV) on cardiopulmonary function after severe pulmonary contusion. Mongrel pigs (32 +/- 1 kg) were anesthetized, paralyzed, and mechanically ventilated (8-10 mL/kg tidal volume; 12 breaths/min; FiO2 = 0.5). Systemic hemodynamics and pulmonary function were measured for 7 hours after a captive bolt gun delivered a blunt injury to the right chest. After 5 hours, FiO2 was increased to 1.0 and either PEEP (n = 7) in titrated increments to 25 cm H2O or PLV with perflubron (LiquiVent, 30 mL/kg, endotracheal) and no PEEP (n = 7) was administered for 2 hours. Two control groups received injury without treatment (n = 6) or no injury with PLV (n = 3). Fluids were liberalized with PEEP versus PLV (27 +/- 3 vs. 18 +/- 2 mL.kg-1.h-1) to maintain cardiac filling pressures. Before treatment at 5 hours after injury, physiologic dead space fraction (30 +/- 4%), pulmonary vascular resistance (224 +/- 20% of baseline), and airway resistance (437 +/- 110% of baseline) were all increased (p < 0.05). In addition, PaO2/FiO2 had decreased to 112 +/- 18 mm Hg, compliance was depressed to 11 +/- 1 mL/cm H2O (36 +/- 3% of baseline), and shunt fraction was increased to 22 +/- 4% (all p < 0.05). Blood pressure and cardiac index remained stable relative to baseline, but stroke index and systemic oxygen delivery were depressed by 15 to 30% (both p < 0.05). After 2 hours of treatment with PEEP versus PLV, PO2/FiO2 was higher (427 +/- 20 vs. 263 +/- 37) and dead space ventilation was lower (4 +/- 3 vs. 28 +/- 7%) (both p < 0.05), whereas compliance tended to be higher (26 +/- 2 vs. 20 +/- 2) and shunt fraction tended to be lower (0 +/- 0 vs. 7 +/- 4). With PEEP versus PLV, however, cardiac index, stroke index, and systemic oxygen delivery were 30 to 60% lower (all p < 0.05). Furthermore, although contused lungs showed similar damage with either treatment, the secondary injury in the contralateral lung (as manifested by intra-alveolar hemorrhage) was more severe with PEEP than with PLV. Both PEEP and PLV improved pulmonary function after severe unilateral pulmonary contusion, but negative hemodynamic and histologic changes were associated with PEEP and not with PLV. These data suggest that PLV is a promising novel ventilatory strategy for unilateral pulmonary contusion that might ameliorate secondary injury in the contralateral uninjured lung.

The alveolar to arterial oxygen partial pressure difference is associated with pulmonary diffusing capacity in heart failure patients.

PubMed

Morosin, Marco; Vignati, Carlo; Novi, Angela; Salvioni, Elisabetta; Veglia, Fabrizio; Alimento, Marina; Merli, Guido; Sciomer, Susanna; Sinagra, Gianfranco; Agostoni, Piergiuseppe

2016-11-01

In chronic heart failure (HF), the alveolar-capillary membrane undergoes a remodeling process that negatively affects gas exchange. In case of alveolar-capillary gas diffusion impairment, arterial desaturation (SaO 2 ) is rarely observed in HF patients. At play are 3 factors: overall pulmonary diffusing capacity (assessed as lung diffusion for CO, DLCO), global O 2 consumption (VO 2 ) and alveolar (A) to arterial (a) pO 2 gradient (AaDO 2 ). In 100 consecutive stable HF patients, DLCO, resting respiratory gases and arterial blood gases were measured to determine VO 2, paO 2 , pAO 2 and AaDO 2 . DLCO was poorly but significantly related to AaDO 2 . The correlation improved after correcting AaDO 2 for VO 2 (p<0.001, r=0.49). Both VO 2 and AaDO 2 were independently associated with DLCO (p<0.001). Patients with reduced DLCO showed no differences as regards paO 2 and pAO 2 . AaDO 2 /VO 2 showed a higher gradient in patients with lower DLCO. AaDO 2 increase and VO 2 reduction allow preventing low SaO 2 in HF patients with reduced DLCO. Accordingly, we suggest considering AaDO 2 and VO 2 combined and reporting AaDO 2 /VO 2 . Copyright © 2016 Elsevier B.V. All rights reserved.

Why O2 is required by complex life on habitable planets and the concept of planetary "oxygenation time".

PubMed

Catling, David C; Glein, Christopher R; Zahnle, Kevin J; McKay, Christopher P

2005-06-01

Life is constructed from a limited toolkit: the Periodic Table. The reduction of oxygen provides the largest free energy release per electron transfer, except for the reduction of fluorine and chlorine. However, the bonding of O2 ensures that it is sufficiently stable to accumulate in a planetary atmosphere, whereas the more weakly bonded halogen gases are far too reactive ever to achieve significant abundance. Consequently, an atmosphere rich in O2 provides the largest feasible energy source. This universal uniqueness suggests that abundant O2 is necessary for the high-energy demands of complex life anywhere, i.e., for actively mobile organisms of approximately 10(-1)-10(0) m size scale with specialized, differentiated anatomy comparable to advanced metazoans. On Earth, aerobic metabolism provides about an order of magnitude more energy for a given intake of food than anaerobic metabolism. As a result, anaerobes do not grow beyond the complexity of uniseriate filaments of cells because of prohibitively low growth efficiencies in a food chain. The biomass cumulative number density, n, at a particular mass, m, scales as n (> m) proportional to m(-1) for aquatic aerobes, and we show that for anaerobes the predicted scaling is n proportional to m (-1.5), close to a growth-limited threshold. Even with aerobic metabolism, the partial pressure of atmospheric O2 (P(O2)) must exceed approximately 10(3) Pa to allow organisms that rely on O2 diffusion to evolve to a size approximately 10(3) m x P(O2) in the range approximately 10(3)-10(4) Pa is needed to exceed the threshold of approximately 10(2) m size for complex life with circulatory physiology. In terrestrial life, O(2) also facilitates hundreds of metabolic pathways, including those that make specialized structural molecules found only in animals. The time scale to reach P(O(2)) approximately 10(4) Pa, or "oxygenation time," was long on the Earth (approximately 3.9 billion years), within almost a factor of 2 of the Sun's main sequence lifetime. Consequently, we argue that the oxygenation time is likely to be a key rate-limiting step in the evolution of complex life on other habitable planets. The oxygenation time could preclude complex life on Earth-like planets orbiting short-lived stars that end their main sequence lives before planetary oxygenation takes place. Conversely, Earth-like planets orbiting long-lived stars are potentially favorable habitats for complex life.

Growth Responses of Neurospora crassa to Increased Partial Pressures of the Noble Gases and Nitrogen

PubMed Central

Buchheit, R. G.; Schreiner, H. R.; Doebbler, G. F.

1966-01-01

Buchheit, R. G. (Union Carbide Corp., Tonawanda, N.Y.), H. R. Schreiner, and G. F. Doebbler. Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen. J. Bacteriol. 91:622–627. 1966.—Growth rate of the fungus Neurospora crassa depends in part on the nature of metabolically “inert gas” present in its environment. At high partial pressures, the noble gas elements (helium, neon, argon, krypton, and xenon) inhibit growth in the order: Xe > Kr> Ar ≫ Ne ≫ He. Nitrogen (N2) closely resembles He in inhibitory effectiveness. Partial pressures required for 50% inhibition of growth were: Xe (0.8 atm), Kr (1.6 atm), Ar (3.8 atm), Ne (35 atm), and He (∼ 300 atm). With respect to inhibition of growth, the noble gases and N2 differ qualitatively and quantitatively from the order of effectiveness found with other biological effects, i.e., narcosis, inhibition of insect development, depression of O2-dependent radiation sensitivity, and effects on tissue-slice glycolysis and respiration. Partial pressures giving 50% inhibition of N. crassa growth parallel various physical properties (i.e., solubilities, solubility ratios, etc.) of the noble gases. Linear correlation of 50% inhibition pressures to the polarizability and of the logarithm of pressure to the first and second ionization potentials suggests the involvement of weak intermolecular interactions or charge-transfer in the biological activity of the noble gases. PMID:5883104

Carbon Monoxide, Hydrogen, and Formate Metabolism during Methanogenesis from Acetate by Thermophilic Cultures of Methanosarcina and Methanothrix Strains.

PubMed

Zinder, S H; Anguish, T

1992-10-01

CO and H(2) have been implicated in methanogenesis from acetate, but it is unclear whether they are directly involved in methanogenesis or electron transfer in acetotrophic methanogens. We compared metabolism of H(2), CO, and formate by cultures of the thermophilic acetotrophic methanogens Methanosarcina thermophila TM-1 and Methanothrix sp. strain CALS-1. M. thermophila accumulated H(2) to partial pressures of 40 to 70 Pa (1 Pa = 0.987 x 10 atm), as has been previously reported for this and other Methanosarcina cultures. In contrast, Methanothrix sp. strain CALS-1 accumulated H(2) to maximum partial pressures near 1 Pa. Growing cultures of Methanothrix sp. strain CALS-1 initially accumulated CO, which reached partial pressures near 0.6 Pa (some CO came from the rubber stopper) during the middle of methanogenesis; this was followed by a decrease in CO partial pressures to less than 0.01 Pa by the end of methanogenesis. Accumulation or consumption of CO by cultures of M. thermophila growing on acetate was not detected. Late-exponential-phase cultures of Methanothrix sp. strain CALS-1, in which the CO partial pressure was decreased by flushing with N(2)-CO(2), accumulated CO to 0.16 Pa, whereas cultures to which ca. 0.5 Pa of CO was added consumed CO until it reached this partial pressure. Cyanide (1 mM) blocked CO consumption but not production. High partial pressures of H(2) (40 kPa) inhibited methanogenesis from acetate by M. thermophila but not by Methanothrix sp. strain CALS-1, and 2 kPa of CO was not inhibitory to M. thermophila but was inhibitory to Methanothrix sp. strain CALS-1. Levels of CO dehydrogenase, hydrogenase, and formate dehydrogenase in Methanothrix sp. strain CALS-1 were 9.1, 0.045, and 5.8 mumol of viologen reduced min mg of protein. These results suggest that CO plays a role in Methanothrix sp. strain CALS-1 similar to that of H(2) in M. thermophila and are consistent with the conclusion that CO is an intermediate in a catabolic or anabolic pathway in Methanothrix sp. strain CALS-1; however, they could also be explained by passive equilibration of CO with a metabolic intermediate.

Carbon Monoxide, Hydrogen, and Formate Metabolism during Methanogenesis from Acetate by Thermophilic Cultures of Methanosarcina and Methanothrix Strains

PubMed Central

Zinder, S. H.; Anguish, T.

1992-01-01

CO and H2 have been implicated in methanogenesis from acetate, but it is unclear whether they are directly involved in methanogenesis or electron transfer in acetotrophic methanogens. We compared metabolism of H2, CO, and formate by cultures of the thermophilic acetotrophic methanogens Methanosarcina thermophila TM-1 and Methanothrix sp. strain CALS-1. M. thermophila accumulated H2 to partial pressures of 40 to 70 Pa (1 Pa = 0.987 × 10-5 atm), as has been previously reported for this and other Methanosarcina cultures. In contrast, Methanothrix sp. strain CALS-1 accumulated H2 to maximum partial pressures near 1 Pa. Growing cultures of Methanothrix sp. strain CALS-1 initially accumulated CO, which reached partial pressures near 0.6 Pa (some CO came from the rubber stopper) during the middle of methanogenesis; this was followed by a decrease in CO partial pressures to less than 0.01 Pa by the end of methanogenesis. Accumulation or consumption of CO by cultures of M. thermophila growing on acetate was not detected. Late-exponential-phase cultures of Methanothrix sp. strain CALS-1, in which the CO partial pressure was decreased by flushing with N2-CO2, accumulated CO to 0.16 Pa, whereas cultures to which ca. 0.5 Pa of CO was added consumed CO until it reached this partial pressure. Cyanide (1 mM) blocked CO consumption but not production. High partial pressures of H2 (40 kPa) inhibited methanogenesis from acetate by M. thermophila but not by Methanothrix sp. strain CALS-1, and 2 kPa of CO was not inhibitory to M. thermophila but was inhibitory to Methanothrix sp. strain CALS-1. Levels of CO dehydrogenase, hydrogenase, and formate dehydrogenase in Methanothrix sp. strain CALS-1 were 9.1, 0.045, and 5.8 μmol of viologen reduced min-1 mg of protein-1. These results suggest that CO plays a role in Methanothrix sp. strain CALS-1 similar to that of H2 in M. thermophila and are consistent with the conclusion that CO is an intermediate in a catabolic or anabolic pathway in Methanothrix sp. strain CALS-1; however, they could also be explained by passive equilibration of CO with a metabolic intermediate. PMID:16348788

Nitric oxide-mediated suppression of 2,3-bisphosphoglycerate synthesis: therapeutic relevance for environmental hypoxia and sickle cell disease.

PubMed

Bertrand, R

2012-09-01

Though hemoglobin (Hb) is best known for transporting oxygen and metabolic wastes throughout the circulatory system, this erythrocyte protein also acts as a hypoxic sensor, its oxygen saturation dependent on the oxygen partial pressure (pO(2)) which varies throughout the vasculature. The production and transport of the endogenous vasodilator nitric oxide (NO) by Hb is dependent on Hb's oxygen saturation, thereby allowing the protein to auto-regulate blood flow efficiency to meet the relative demands of respiring tissues. Erythrocyte concentrations of 2,3-bisphosphoglycerate (BPG), an enhancer of oxygen off-loading from Hb, is very sensitive to changes in glycolytic rates because its synthesis by BPG synthase is dependent on the availability of the glycolytic intermediate 1,3-bisphosphoglycerate. BPG synthase, as well as some glycolytic enzymes, are also very sensitive to pH changes, and variations in BPG levels have direct consequences on the oxygen off-loading function of Hb. I hypothesize that NO may suppress BPG production by (1) inhibiting glyceraldehyde-3-phosphate dehydrogenase (G3PDH), the most critical glycolytic enzyme for the bioavailability of 1,3-bisphosphoglycerate; and to a lesser extent by (2) associated pH changes in the deoxy-Hb-catalyzed depletion of nitrite, a metabolic reservoir of NO. Both mechanisms are favored in low pO(2) environments where BPG is most needed to maximize oxygen off-loading, indicating that the auto-regulatory link between NO and Hb may have inadvertently linked Hb and BPG synthesis in an unfavorable manner. However, for reasons discussed, NO-mediated suppression of BPG may be advantageous in some circumstances; namely, for individuals living at high altitudes and those with the blood disorder sickle cell anemia. This hypothesis is thus relevant to respiratory health under both normative conditions as well as under hypoxic stress. The potential relevance of the hypothesis to comparative animal physiology and evolutionary biology is also briefly described. Copyright © 2012 Elsevier Ltd. All rights reserved.

What Is Hypotension?

MedlinePlus

... Hypotension Hypotension Also known as What Is Hypotension (HI-po-TEN-shun) is abnormally low blood pressure. ... this type of low blood pressure. Dehydration (de-hi-DRA-shun) is the most common cause of ...

Midterm Outcomes From a Pilot Study of Percutaneous Deep Vein Arterialization for the Treatment of No-Option Critical Limb Ischemia.

PubMed

Kum, Steven; Tan, Yih Kai; Schreve, Michiel A; Ferraresi, Roberto; Varcoe, Ramon L; Schmidt, Andrej; Scheinert, Dierk; Mustapha, Jihad A; Lim, Darryl M; Ho, Derek; Tang, Tjun Y; Alexandrescu, Vlad-Adrian; Mutirangura, Pramook

2017-10-01

To report the initial clinical experience with percutaneous deep vein arterialization (PDVA) to treat critical limb ischemia (CLI) via the creation of an arteriovenous fistula. Seven patients (median age 85 years; 5 women) with CLI and no traditional endovascular or surgical revascularization options (no-option CLI) were recruited in a pilot study to determine the safety of PDVA. All patients were diabetic; 4 had Rutherford category 6 ischemia. Six were classified at high risk of amputation based on the Society for Vascular Surgery WIfI (wound, ischemia, and foot infection) classification. The primary safety endpoints were major adverse limb events and major adverse coronary events through 30 days and serious adverse events through 6 months. Secondary objectives included clinical efficacy based on outcome measures including thermal measurement, transcutaneous partial pressure of oxygen (TcPO 2 ), clinical improvement at 6 months, and wound healing. The primary safety endpoints were achieved in 100% of patients, with no deaths, above-the-ankle amputations, or major reinterventions at 30 days. The technical success rate was 100%. Two myocardial infarctions occurred within 30 days, each with minor clinical consequences. All patients demonstrated symptomatic improvement with formation of granulation tissue, resolution of rest pain, or both. Complete wound healing was achieved in 4 of 7 patients and 5 of 7 patients at 6 and 12 months, respectively, with a median healing time of 4.6 months (95% confidence interval 84-192). Median postprocedure peak TcPO 2 was 61 mm Hg compared to a preprocedure level of 8 mm Hg (p=0.046). At the time of wound healing, 4 of 5 of patients achieved TcPO 2 levels of >40 mm Hg. There were 2 major amputations, 1 above the knee after PDVA thrombosis and 1 below the knee for infection. Three patients died of causes unrelated to the procedure or study device at 6, 7, and 8 months, respectively. Limb salvage was 71% at 12 months. PDVA is an innovative approach for treating no-option CLI and represents an alternative option for the "desert foot," potentially avoiding major amputation. Our results demonstrate its safety and feasibility, with promising early clinical results in this small cohort.

A System for Incubations at High Gas Partial Pressure

PubMed Central

Sauer, Patrick; Glombitza, Clemens; Kallmeyer, Jens

2012-01-01

High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120°C, and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. To keep costs low, the system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow-through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g., fluid–gas–rock-interactions in relation to carbon dioxide sequestration. As an application of the system we extracted organic compounds from sub-bituminous coal using H2O as well as a H2O–CO2 mixture at elevated temperature (90°C) and pressure (5 MPa). Subsamples were taken at different time points during the incubation and analyzed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could detect an increase in sulfate reduction rate upon the addition of methane to the sample. PMID:22347218

Experimental assessment of oxygen homeostasis during acute hemodilution: the integrated role of hemoglobin concentration and blood pressure.

PubMed

Kei, Tiffanie; Mistry, Nikhil; Tsui, Albert K Y; Liu, Elaine; Rogers, Stephen; Doctor, Allan; Wilson, David F; Desjardins, Jean-Francois; Connelly, Kim; Mazer, C David; Hare, Gregory M T

2017-12-01

Low hemoglobin concentration (Hb) and low mean arterial blood pressure (MAP) impact outcomes in critically ill patients. We utilized an experimental model of "normotensive" vs. "hypotensive" acute hemodilutional anemia to test whether optimal tissue perfusion is dependent on both Hb and MAP during acute blood loss and fluid resuscitation, and to assess the value of direct measurements of the partial pressure of oxygen in tissue (P t O 2 ). Twenty-nine anesthetized rats underwent 40% isovolemic hemodilution (1:1) (or sham-hemodilution control, n = 4) with either hydroxyethyl starch (HES) (n = 14, normotensive anemia) or saline (n = 11, hypotensive anemia) to reach a target Hb value near 70 g/L. The partial pressure of oxygen in the brain and skeletal muscle tissue (P t O 2 ) were measured by phosphorescence quenching of oxygen using G4 Oxyphor. Mean arterial pressure (MAP), heart rate, temperature, arterial and venous co-oximetry, blood gases, and lactate were assessed at baseline and for 60 min after hemodilution. Cardiac output (CO) was measured at baseline and immediately after hemodilution. Data were analyzed by repeated measures two-way ANOVA. Following "normotensive" hemodilution with HES, Hb was reduced to 66 ± 6 g/L, CO increased (p < 0.05), and MAP was maintained. These conditions resulted in a reduction in brain P t O 2 (22.1 ± 5.6 mmHg to 17.5 ± 4.4 mmHg, p < 0.05), unchanged muscle PO 2 , and an increase in venous oxygen extraction. Following "hypotensive" hemodilution with saline, Hb was reduced to 79 ± 5 g/L and both CO and MAP were decreased (P < 0.05). These conditions resulted in a more severe reduction in brain P t O 2 (23.2 ± 8.2 to 10.7 ± 3.6 mmHg (p < 0.05), a reduction in muscle P t O 2 (44.5 ± 11.0 to 19.9 ± 12.4 mmHg, p < 0.05), a further increase in venous oxygen extraction, and a threefold increase in systemic lactate levels (p < 0.05). Acute normotensive anemia (HES hemodilution) was associated with a subtle decrease in brain tissue P t O 2 without clear evidence of global tissue hypoperfusion. By contrast, acute hypotensive anemia (saline hemodilution) resulted in a profound decrease in both brain and muscle tissue P t O 2 and evidence of inadequate global perfusion (lactic acidosis). These data emphasize the importance of maintaining CO and MAP to ensure adequacy of vital organ oxygen delivery during acute anemia. Improved methods of assessing P t O 2 may provide an earlier warning signal of vital organ hypoperfusion.

Separating the roles of nitrogen and oxygen in high pressure-induced blood-borne microparticle elevations, neutrophil activation, and vascular injury in mice.

PubMed

Yang, Ming; Bhopale, Veena M; Thom, Stephen R

2015-08-01

An elevation in levels of circulating microparticles (MPs) due to high air pressure exposure and the associated inflammatory changes and vascular injury that occur with it may be due to oxidative stress. We hypothesized that these responses arise due to elevated partial pressures of N2 and not because of high-pressure O2. A comparison was made among high-pressure air, normoxic high-pressure N2, and high-pressure O2 in causing an elevation in circulating annexin V-positive MPs, neutrophil activation, and vascular injury by assessing the leakage of high-molecular-weight dextran in a murine model. After mice were exposed for 2 h to 790 kPa air, there were over 3-fold elevations in total circulating MPs as well as subgroups bearing Ly6G, CD41, Ter119, CD31, and CD142 surface proteins-evidence of neutrophil activation; platelet-neutrophil interaction; and vascular injury to brain, omentum, psoas, and skeletal muscles. Similar changes were found in mice exposed to high-pressure N2 using a gas mixture so that O2 partial pressure was the same as that of ambient air, whereas none of these changes occurred after exposures to 166 kPa O2, the same partial pressure that occurs during high-pressure air exposures. We conclude that N2 plays a central role in intra- and perivascular changes associated with exposure to high air pressure and that these responses appear to be a novel form of oxidative stress. Copyright © 2015 the American Physiological Society.

Perpendicular magnetic anisotropy and magnetization dynamics in oxidized CoFeAl films

PubMed Central

Wu, Di; Zhang, Zhe; Li, Le; Zhang, Zongzhi; Zhao, H. B.; Wang, J.; Ma, B.; Jin, Q. Y.

2015-01-01

Half-metallic Co-based full-Heusler alloys with perpendicular magnetic anisotropy (PMA), such as Co2FeAl in contact with MgO, are receiving increased attention recently due to its full spin polarization for high density memory applications. However, the PMA induced by MgO interface can only be realized for very thin magnetic layers (usually below 1.3 nm), which would have strong adverse effects on the material properties of spin polarization, Gilbert damping parameter, and magnetic stability. In order to solve this issue, we fabricated oxidized Co50Fe25Al25 (CFAO) films with proper thicknesses without employing the MgO layer. The samples show controllable PMA by tuning the oxygen pressure (PO2) and CFAO thickness (tCFAO), large perpendicular anisotropy field of ~8.0 kOe can be achieved at PO2 = 12% for the sample of tCFAO = 2.1 nm or at PO2 = 7% for tCFAO = 2.8 nm. The loss of PMA at thick tCFAO or high PO2 results mainly from the formation of large amount of CoFe oxides, which are superparamagnetic at room temperature but become hard magnetic at low temperatures. The magnetic CFAO films, with strong PMA in a relatively wide thickness range and small intrinsic damping parameter below 0.028, would find great applications in developing advanced spintronic devices. PMID:26190066

Interface Control of Ferroelectricity in an SrRuO3 /BaTiO3 /SrRuO3 Capacitor and its Critical Thickness.

PubMed

Shin, Yeong Jae; Kim, Yoonkoo; Kang, Sung-Jin; Nahm, Ho-Hyun; Murugavel, Pattukkannu; Kim, Jeong Rae; Cho, Myung Rae; Wang, Lingfei; Yang, Sang Mo; Yoon, Jong-Gul; Chung, Jin-Seok; Kim, Miyoung; Zhou, Hua; Chang, Seo Hyoung; Noh, Tae Won

2017-05-01

The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (PO2) during growth plays an important role in controlling the interfacial terminations of SrRuO 3 /BaTiO 3 /SrRuO 3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high PO2 (around 150 mTorr), usually exhibits a mixture of RuO 2 -BaO and SrO-TiO 2 terminations. By reducing PO2, the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO 2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Optimization of blood gas analysis in intensive care units : Reduction of preanalytical errors and improvement of workflow].

PubMed

Kieninger, M; Zech, N; Mulzer, Y; Bele, S; Seemann, M; Künzig, H; Schneiker, A; Gruber, M

2015-05-01

Point of care testing with blood gas analysis (BGA) is an important factor for intensive care medicine. Continuous efforts to optimize workflow, improve safety for the staff and avoid preanalytical mistakes are important and should reflect quality management standards. In a prospective observational study it was investigated whether the implementation of a new system for BGA using labeled syringes and automated processing of the specimens leads to improvements compared to the previously used procedure. In a 4-week test period the time until receiving the final results of the BGA with the standard method used in the clinical routine (control group) was compared to the results in a second 4-week test period using the new labeled syringes and automated processing of the specimens (intervention group). In addition, preanalytical mistakes with both systems were checked during routine daily use. Finally, it was investigated whether a delay of 10 min between taking and analyzing the blood samples alters the results of the BGA. Preanalytical errors were frequently observed in the control group where non-deaerated samples were recorded in 87.3 % but in the intervention group almost all samples (98.9 %) were correctly deaerated. Insufficient homogenization due to omission of manual pivoting was seen in 83.2 % in the control group and in 89.9 % in the intervention group; however, in the intervention group the samples were homogenized automatically during the further analytical process. Although a survey among the staff revealed a high acceptance of the new system and a subjective improvement of workflow, a measurable gain in time after conversion to the new procedure could not be seen. The mean time needed for a complete analysis process until receiving the final results was 244 s in the intervention group and 201 s in the control group. A 10-min delay between taking and analyzing the blood samples led to a significant and clinically relevant elevation of the values for partial pressure of oxygen (pO2) in both groups compared to the results when analyzing the samples immediately (118.4 vs. 148.6 mmHg in the control group and 115.3 vs. 123.7 mmHg in the intervention group). When using standard syringes the partial pressure of carbon dioxide (pCO2) was significantly lower (40.5 vs. 38.3 mmHg) whereas no alterations were seen when using the labeled syringes. The implementation of a new BGA system with labeled syringes and automated processing of the specimens was possible without any difficulties under daily clinical routine conditions in this 10-bed intensive care unit (ICU). A gain of time could not be measured but a reduction in preanalytical errors using the labeled syringes with automated processing was found. Delayed analysis of blood samples can lead to significant changes in pO2 and pCO2 depending on the type of syringe used.

Hyperbaric oxygen therapy (HBOT) in case of hemorrhagic cystitis after radiotherapy

PubMed Central

Klejnotowska, Alicja; Matuszewski, Marcin; Sicko, Zdzislaw; Markuszewski, Marcin; Krajka, Kazimierz

2012-01-01

Introduction We present the effect of hyperbaric oxygen therapy (HBOT) after radiotherapy for cancer in the pelvic cavity resulting in hematuria. Increasing the pressure of oxygen (PO2) in ischemic tissues favors the formation of new blood vessels and increases the secretion of collagen. Material and methods We evaluated 10 patients who were treated with HBOT from October 2006 to December 2010 due to persistent radiation damage to the lining of the bladder leading to recurrent hematuria. The study group was comprised of seven men and three women. In the case of cervical and endometrial cancers, 30 Gy of brachytherapy with 45-50 Gy of teleradiotherapy were used. In prostate cancer (PCa), we applied 50 Gy of teleradiotherapy with an additional dose of 20-24 Gy, and in the case of bladder cancer (BCa), 50 Gy of teleradiotherapy was applied with an additional dose of 16 Gy. HBOT consisted of 60 HBO2 treatments, in which patients were administered 100% oxygen at a pressure of 2.5 atm. Results The group effect of total or partial resolution was observed in six patients. In one case, treatment was discontinued due to an increase in hematuria and the consequent suspicion of bladder tumor recurrence. While in and additional three cases, the treatment did not produce the desired result. Conclusions Treatment of hemorrhagic cystitis is a difficult therapeutic challenge. One possible method is the implementation of HBOT. In very difficult cases, HBO2 treatment appears to be effective in giving more than half of patients a chance of getting better. PMID:24578962

Mass separation of deuterium and helium with conventional quadrupole mass spectrometer by using varied ionization energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Yaowei; Hu, Jiansheng, E-mail: hujs@ipp.ac.cn; Wan, Zhao

2016-03-15

Deuterium pressure in deuterium-helium mixture gas is successfully measured by a common quadrupole mass spectrometer (model: RGA200) with a resolution of ∼0.5 atomic mass unit (AMU), by using varied ionization energy together with new developed software and dedicated calibration for RGA200. The new software is developed by using MATLAB with the new functions: electron energy (EE) scanning, deuterium partial pressure measurement, and automatic data saving. RGA200 with new software is calibrated in pure deuterium and pure helium 1.0 × 10{sup −6}–5.0 × 10{sup −2} Pa, and the relation between pressure and ion current of AMU4 under EE = 25 eVmore » and EE = 70 eV is obtained. From the calibration result and RGA200 scanning with varied ionization energy in deuterium and helium mixture gas, both deuterium partial pressures (P{sub D{sub 2}}) and helium partial pressure (P{sub He}) could be obtained. The result shows that deuterium partial pressure could be measured if P{sub D{sub 2}} > 10{sup −6} Pa (limited by ultimate pressure of calibration vessel), and helium pressure could be measured only if P{sub He}/P{sub D{sub 2}} > 0.45, and the measurement error is evaluated as 15%. This method is successfully employed in EAST 2015 summer campaign to monitor deuterium outgassing/desorption during helium discharge cleaning.« less

Hemodynamic deterioration precedes onset of ventricular tachyarrhythmia after Heartmate II implantation.

PubMed

Yaksh, Ameeta; Kik, Charles; Knops, Paul; Zwiers, Korinne; van Ettinger, Maarten J B; Manintveld, Olivier C; de Wijs, Marcel C J; van der Kemp, Peter; Bogers, Ad J J C; de Groot, Natasja M S

2016-07-08

Early postoperative ventricular tachyarrhythmia (PoVT) after left ventricular assist device (LVAD) implantation are common and associated with higher mortality-rates. At present, there is no data on initiation of these PoVT and the role of alterations in cardiac hemodynamics. A LVAD was implanted in a patient with end-stage heart failure due to a ischemic cardiomyopathy. Alterations in cardiac rhythm and hemodynamics preceding PoVT-episodes during the first five postoperative days were examined by using continuous recordings of cardiac rhythm and various hemodynamic parameters. All PoVT (N=120) were monomorphic, most often preceded by short-long-short-sequences or regular SR and initiated by ventricular runs. Prior to PoVT, mean arterial pressure decreased; heart rate and ST-segments deviations increased. PoVT are caused by different underlying electrophysiological mechanisms. Yet, they are all monomorphic and preceded by hemodynamic deterioration due to myocardial ischemia.

Bulk YBa2Cu3O(x) superconductors through pressurized partial melt growth processing

NASA Technical Reports Server (NTRS)

Hu, S.; Hojaji, H.; Barkatt, A.; Boroomand, M.; Hung, M.; Buechele, A. C.; Thorpe, A. N.; Davis, D. D.; Alterescu, S.

1992-01-01

A novel pressurized partial melt growth process has been developed for producing large pieces of bulk Y-Ba-Cu-O superconductors. During long-time partial melt growth stage, an additional driving force for solidification is obtained by using pressurized oxygen gas. The microstructure and superconducting properties of the resulting samples were investigated. It was found that this new technique can eliminate porosity and inhomogeneity, promote large-scale grain-texturing, and improve interdomain coupling as well.

Selective Oxidation of a 0.1C-6Mn-2Si Third Generation Advanced High-Strength Steel During Dew-Point Controlled Annealing

NASA Astrophysics Data System (ADS)

Pourmajidian, Maedeh; McDermid, Joseph R.

2018-03-01

The present study investigates the selective oxidation of a 0.1C-6Mn-2Si medium-Mn advanced high-strength steel during austenization annealing heat treatments as a function of process atmosphere oxygen partial pressure and annealing time. It was determined that the surface oxide growth kinetics followed a parabolic rate law with the minimum rate belonging to the lowest oxygen partial pressure atmosphere at a dew point of 223 K (- 50 °C). The chemistry of the surface and subsurface oxides was studied using STEM + EELS on the sample cross sections, and it was found that the surface oxides formed under the 223 K (- 50 °C) dew-point atmosphere consisted of a layered configuration of SiO2, MnSiO3, and MnO, while in the case of the higher pO2 process atmospheres, only MnO was detected at the surface. Consistent with the Wagner calculations, it was shown that the transition to internal oxidation for Mn occurred under the 243 K (- 30 °C) and 278 K (+ 5 °C) dew-point atmospheres. However, the predictions of the external to internal oxidation for Si using the Wagner model did not correlate well with the experimental findings nor did the predictions of the Mataigne et al. model for multi-element alloys. Investigations of the internal oxide network at the grain boundaries revealed a multilayer oxide structure composed of amorphous SiO2 and crystalline MnSiO3, respectively, at the oxide core and outer shell. A mechanism for the formation of the oxide morphologies observed, based on kinetic and thermodynamic factors, was proposed. It is expected that only the fine and nodule-like MnO oxides formed on the surface of the samples annealed under the 278 K (+ 5 °C) dew-point process atmosphere for 60 and 120 seconds are sufficiently thin and of the desired dispersed morphology to promote reactive wetting by the molten galvanizing bath.

Increased blood glycohemoglobin A1c levels lead to overestimation of arterial oxygen saturation by pulse oximetry in patients with type 2 diabetes

PubMed Central

2012-01-01

Background Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin. Objectives We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO2) in type 2 diabetic patients during mechanical ventilation or oxygen therapy. Methods Arterial oxygen saturation (SaO2) and partial pressure of oxygen (PO2) were determined with simultaneous monitoring of SpO2 in 261 type 2 diabetic patients during ventilation or oxygen inhalation. Results Blood concentration of HbA1c was >7% in 114 patients and ≤ 7% in 147 patients. Both SaO2 (96.2 ± 2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1 ± 2.8%, 95% CI 94.7-95.6%) and SpO2 (98.0 ± 2.6%, 95% CI 97.6-98.5% vs. 95.3 ± 2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c ≤ 7% (Data are mean ± SD, all p < 0.01), but PO2 did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO2 and SaO2 (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO2 and SaO2 correlated closely with blood HbA1c levels (Pearson’s r = 0.307, p < 0.01). Conclusions Elevated blood HbA1c levels lead to an overestimation of SaO2 by SpO2, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia. PMID:22985301

Increased blood glycohemoglobin A1c levels lead to overestimation of arterial oxygen saturation by pulse oximetry in patients with type 2 diabetes.

PubMed

Pu, Li Jin; Shen, Ying; Lu, Lin; Zhang, Rui Yan; Zhang, Qi; Shen, Wei Feng

2012-09-17

Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin. We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO2) in type 2 diabetic patients during mechanical ventilation or oxygen therapy. Arterial oxygen saturation (SaO2) and partial pressure of oxygen (PO2) were determined with simultaneous monitoring of SpO2 in 261 type 2 diabetic patients during ventilation or oxygen inhalation. Blood concentration of HbA1c was >7% in 114 patients and ≤ 7% in 147 patients. Both SaO2 (96.2 ± 2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1 ± 2.8%, 95% CI 94.7-95.6%) and SpO2 (98.0 ± 2.6%, 95% CI 97.6-98.5% vs. 95.3 ± 2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c ≤ 7% (Data are mean ± SD, all p < 0.01), but PO2 did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO2 and SaO2 (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO2 and SaO2 correlated closely with blood HbA1c levels (Pearson's r = 0.307, p < 0.01). Elevated blood HbA1c levels lead to an overestimation of SaO2 by SpO2, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia.

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. 868.1150 Section 868.1150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... “Class II Special Controls Guidance Document: Indwelling Blood Gas Analyzers; Final Guidance for Industry...

Classifying Acute Respiratory Distress Syndrome Severity: Correcting the Arterial Oxygen Partial Pressure to Fractional Inspired Oxygen at Altitude.

PubMed

Pérez-Padilla, Rogelio; Hernández-Cárdenas, Carmen Margarita; Lugo-Goytia, Gustavo

2016-01-01

In the well-known Berlin definition of acute respiratory distress syndrome (ARDS), there is a recommended adjustment for arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FIO2) at altitude, but without a reference as to how it was derived.

Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses

NASA Astrophysics Data System (ADS)

Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

2012-12-01

Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus of CO2 displays a strong compositional effect. If these compositional dependencies persist in the analogue melts, the partial molar volume of dissolved CO2 will depend on melt composition, both at low and elevated pressure. Thus, for CO2-bearing melts, a full quantitative understanding of density dependent magmatic processes, such as crystal fractionation, magma mixing and melt extraction will require in situ measurements for a range of melt compositions. [1] Richet, P. et al., 2000, Contrib Mineral Petrol, 138, 337-347. [2] Malfait et al. 2011, Am. Mineral. 96, 1402-1409. [3] Whittington et al., 2012, Am. Mineral. 97, 455-467.