Changes In Oxygen Partial Pressure Research Articles

#1651 Urinary oxygen partial pressure: closely associated with hourly urine output induced by furosemide in patients with acute renal injury

Abstract Background and Aims Urine oxygen level, an indicator of kidney medullar oxygenation, is promising for predicting the onset of acute kidney injury (AKI). Furosemide, a commonly used diuretic in ICU, significantly increases urine output and is believed to change kidney medullar oxygenation. We monitored the longitudinal change of urinary oxygen partial pressure during bolus or pump administration of furosemide, aiming to describe the reaction pattern in an AKI-susceptible patient population. Method The prospective observational pilot study included seven adult patients in the ICU because of cardiac surgery or sepsis. We monitored the continuous urinary oxygen partial pressure for 8-24 hours through a device placed between the urinary catheter and collecting bag during furosemide administration, recorded hourly urine output simultaneously from a urine bag, and followed the patients in the hospital for the onset and development of AKI. Results We recruited three female patients and four male patients with an average age of 54 years and a medium of 5 days in ICU with an AKIN stage I of AKI during their hospital stay. None of them developed more severe stage AKI or required any kidney replacement therapy. We found a reverse correlation pattern between hourly urine output and urinary oxygen partial pressure. Specifically, the urine oxygen level dropped during urine volume increase caused by furosemide bolus administration and abolished by furosemide administration through a pump with more stable urine output. The paired t-test showed a significant increase in average urine oxygen level (mean difference = 21.2 mmHg, p = 0.044) recorded during the “high hourly urine output” period compared to the “low hourly urine period”. Conclusion We first found a drop in urinary oxygen partial pressure during the high urine output period elicited by bolus furosemide administration. It shed light on the confounding factors in AKI predicating during possible furosemide administration.

Simulated Abrupt Shifts in Aerobic Habitats of Marine Species in the Past, Present, and Future

AbstractThe physiological tolerances of marine species toward ambient temperature and oxygen can jointly be evaluated in a single metric: the metabolic index. Changes therein characterize a changing aerobic habitat tailored to species‐specific thermal and hypoxia sensitivity traits. If the geographical limits of marine species as indicated by critical thresholds of the metabolic index shift abruptly in response to ocean warming and deoxygenation, aerobic habitat could potentially be lost abruptly. Here, we assess the spatio‐temporal detectability of abrupt shifts in potential habitats for selected marine species within the Shared Socioeconomic Pathway 5–8.5 (SSP5‐8.5) scenario run with the fully coupled Norwegian Earth System Model version 2 (NorESM2‐LM). We use an environmental time series changepoint detection routine and analyze the number and timing of these abrupt changes over the past, present and future. We construct nine ecophysiotypes with low, medium, and high resting vulnerability to hypoxia and sensitivity of hypoxia vulnerability to temperature, respectively, with six different thresholds for minimal oxygen demand. For all ecophysiotypes with positive temperature sensitivity to hypoxia, the volume of non‐viable habitat in the upper ocean expands between 1850 and 2100. Changepoints in the metabolic index are detected in 49.0 ± 9.2% of the volume that eventually becomes non‐viable for all ecophysiotypes over the course of the 21st century. More than 75% of these abrupt shifts occur in response to warming close to the surface, while at depth, the abrupt shifts driven by changes in oxygen partial pressure become more important, with potentially severe consequences for marine species, populations, and ecosystems.

Von Willebrand factor hyperactivity affects the outcome of lower limb revascularization in subjects with type 2 diabetes mellitus complicated by diabetic foot vasculopathy: An observational pilot study

Aim of this study is to evaluate any differences in VWF antigen, VWF activity and ADAMTS-13 activity before and after successful and non-successful Percutaneous Transluminal Angioplasty (PTA) in subjects with type 2 diabetes (T2DM) complicated by Chronic limb-threatening ischemia (CLTI) in diabetic foot vasculopathy. MethodsIn this prospective observational pilot study, we enrolled 35 T2DM subjects who underwent lower limb PTA. Transcutaneous oximetry was performed in all patients before and 6 weeks after PTA. The change in oxygen partial pressure (TcpO2) before and after PTA was expressed as TcpO2-delta (ΔTcpO2). VWF antigen, VWF activity and ADAMTS-13 activity were measured before and 6 weeks after PTA; changes were expressed as delta and ratio from baseline. ResultsSubjects with ∆TcpO2 < 15 mmHg presented higher ΔVWF activity (p = 0.050) and lower ADAMTS-13 activity ratio (p = 0.080). Subjects with ∆TcpO2 < 30 mmHg showed lower ADAMTS-13 activity Δ and ratio (p = 0.028). ConclusionsVWF antigen levels and VWF activity may potentially affect PTA outcome. Higher levels of VWF could derive from VWF release as consequence of PTA-induced mechanical endothelial damage and/or oxidative stress-induced modifications of VWF structure with impairment of VWF-ADAMTS13 interactions.

Monitoring Internal Oxygen Partial Pressure in YSZ Electrolyte Under Electrolysis Cell Mode Using 4-Electrode System

When solid oxide cells are operated in electrolysis mode, high oxygen pressures can be developed in electrolyte near the oxygen electrode/ electrolyte interface, leading to oxygen electrode delamination. Monitoring oxygen partial pressure in the electrolyte is necessary for the prevention of catastrophic failure in solid oxide electrolysis cells (SOECs). In this study, we applied four-electrode system to fuel electrode-supported SOECs. Four–electrode consists of air electrode, fuel electrode, Pt probe embedded in electrolyte and Pt reference electrode on the electrolyte edge. We measured internal electric potential near the oxygen electrode with respect to the reference electrode using embedded Pt probe. Based on this experimental setup, internal partial pressure of oxygen at the Pt probe location was determined. As tracing changes in internal oxygen partial pressure with varying overvoltage or current density, we investigated the relationship between operating conditions and the tendency of chemo-mechanical failure in solid oxide electrolysis cells.

A Prototype Wearable Device for Noninvasive Monitoring of Transcutaneous Oxygen.

Transcutaneous oxygen monitoring is a noninvasive method for measuring the partial pressure of oxygen diffusing through the skin, which strongly correlates with changes in dissolved oxygen in the arteries. Luminescent oxygen sensing is one of the techniques for assessing transcutaneous oxygen. Intensity- and lifetime-based measurements are two well-known methods used in this technique. The latter is more immune to optical path changes and reflections, making the measurements less vulnerable to motion artifacts and skin color changes. Although the lifetime-based method is promising, the acquisition of high-resolution lifetime data is crucial for accurate transcutaneous oxygen measurements from the human body when skin is not heated. We have built a compact prototype along with its custom firmware for the lifetime estimation of transcutaneous oxygen with a provision of a wearable device. Furthermore, we performed a small experiment study on three healthy human volunteers to prove the concept of measuring oxygen diffusing from the skin without heating. Lastly, the prototype successfully detected changes in lifetime values driven by the changes in transcutaneous oxygen partial pressure due to pressure-induced arterial occlusion and hypoxic gas delivery. The prototype resolved a minimum change of 1.34ns in a lifetime that corresponds to ∼0.031mmHg in response to slow changes in the oxygen pressure in the volunteer's body caused by hypoxic gas delivery. The prototype is believed to be the first in the literature to successfully conduct measurements in human subjects using the lifetime-based technique.

Integration of fluorophore-based sensor spots into food packaging systems for the non-destructive real-time determination of oxygen

Oxygen is an important filling gas for modified atmosphere food packaging. To measure the oxygen amount non-destructively in the headspace, the integration of fluorescence material into the packaging system is a meaningful method, as oxygen serves as quencher for dynamic fluorescence. In this study, the integration of fluorescencent material into packaging films using a heat-sealing process was successfully demonstrated. Real-time determination of changes in oxygen partial pressure was also possible, with some limitations. The use of the technology for the determination of food quality changes (microbiological growth and color changes) were evaluated with high-oxygen stored minced beef (7 d, 4 °C), vacuum-packed sausage “Lyoner” type and beef steak (13 d, 4 °C). The increase in total viable count to the critical value of 107 CFU/g and the change of the surface color was well in common with the oxygen decrease for the high-oxygen packed minced beef. The vacuum packaged samples also showed correlations between reaching the critical microbiological value and a significant decrease of oxygen. However, no color changes were visible in that case.

Comment on the article of R. Iu. Ovsiannikov and K. M. Lebedinskii “Correlation between changes in arterial blood oxygen partial pressure, oxygen uptake and carbon dioxide elimination by the lungs with changes in positive end expiratory pressure: a prospe

Comment on the article of R.Iu. Ovsiannikov and K.M. Lebedinskii “Correlation between changes in arterial blood oxygen partial pressure, oxygen uptake and carbon dioxide elimination by the lungs with changes in positive end expiratory pressure: a prospective observational study”

Quantitative analysis of oxygen partial pressure measurements based on photoacoustic pump-probe imaging

Pump-probe-based photoacoustic imaging is an innovative technique for high-specificity molecular imaging in deep tissues. Compared with conventional photoacoustic imaging, this method effectively eliminates the interference from blood signal and other background signal, enabling the detection of subtle target molecules. Additionally, the manipulating of the time delay between the pump laser and probe laser can facilitate non-invasive mapping of oxygen partial pressure distribution within tissues. To quantify the photoacoustic pump-probe imaging, we use methylene blue as the molecular probe to monitor changes in oxygen partial pressure within a hemoglobin solution. Utilizing a Gaussian noise model, we investigate the relationship between the stability of the triplet-state difference signal and the average number, and also evaluate the error associated with measuring oxygen partial pressure. The results demonstrate that the detection accuracy of the system is better than 33 mmHg (1 mmHg = 133 Pa) in the oxygen partial pressure range of about 300 to 550 mmHg after 200 times of averaging. This research will play a significant role in guiding the further advancement and application of pump-probe-based photoacoustic imaging technology.

Phosphorescent Microneedle Array for the Measurement of Oxygen Partial Pressure in Tissue.

The knowledge of the exact oxygen partial pressure in tissue is crucial for patient care and in the treatment of ischemic medical conditions. However, current methods to assess oxygen partial pressure in tissue suffer from a variety of disadvantages, including complex equipment and procedures that necessitate trained personnel. Additionally, the barrier function of the stratum corneum reduces oxygen exchange and can consequently hamper surface measurements of rapidly changing oxygen partial pressure in tissue. To overcome these challenges, a novel, easy-to-use technique to monitor the oxygen partial pressure in tissue using microneedle arrays (MNAs) has been developed. The MNAs can be made from poly(ethyl methacrylate) and poly(propyl methacrylate) and overcome the skin's barrier function to measure oxygen in the capillary bed and interstitial fluid of the skin. The MNAs' tips are embedded with an oxygen-sensitive phosphorescent metalloporphyrin, where the oxygen partial pressure inversely correlates to changes in both emission intensity and phosphorescence lifetime of the in-house developed red emitting Pt-core porphyrin. It was demonstrated that the oxygen-sensing MNAs are sufficiently robust to puncture human skin via rupture of the stratum corneum, and that the MNAs can detect changes in oxygen partial pressure in skin within the physiologically relevant range (0-160 mmHg). Additionally, the MNAs can be combined with a wearable wireless optical readout system, making these oxygen-sensing MNAs a novel wearable and portable method for user-friendly monitoring of oxygen partial pressure in skin.

High-Temperature 2D Optical Relaxation Visualizes Enhanced Oxygen Exchange Kinetics at Metal-Mixed Conducting Oxide Interfaces.

Solid-state heterointerfaces are of interest for emergent local behavior that is distinct from either bulk parent compound. One technologically relevant example is the case of mixed ionic/electronic conductor (MIEC)-metal interfaces, which play an important role in electrochemistry. Metal-MIEC composite electrodes can demonstrate improved catalytic activity vs single-phase MIECs, improving fuel cell efficiency. Similarly, MIEC surface reaction kinetics are often evaluated using techniques that place metal current collectors in contact with the surface under evaluation, potentially altering the response vs the native surface. Techniques enabling direct and local in situ observation of the behavior at and around such heterointerfaces are needed. Here, we develop a spatially resolved optical transmission relaxation (2D-OTR) method providing continuous evaluation of local, high-temperature, controlled atmosphere defect kinetics across a ∼1 cm2 sample area simultaneously in a contact-free manner. We apply it to observe the spatial variance of oxygen incorporation and evolution rates at ∼525-620 °C, in response to step changes in oxygen partial pressure, on MIEC SrTi0.65Fe0.35O3-x films as a function of distance from porous Pt and Au layers. Using this model geometry, we find significant enhancements in kinetics adjacent to the metals that decay over a few millimeter distance. To extract kinetic parameters, we fit the short-term optical data (initial portion of relaxations) with an exponential decay function appropriate for surface-exchange-limited kinetics, yielding apparent surface exchange coefficients (kchem) with spatial resolution, decreasing with distance from the metal. To understand the kinetic processes governing the complete (long-term) optical relaxations, we performed COMSOL simulations, which demonstrated that a combination of laterally varying kchem and in-plane diffusion controls the observed kinetics over the full time range. Further support for spatially varying kchem comes from demonstrations of changing surface and bulk chemistry vs distance from the metal-MIEC interface, by X-ray photoelectron and optical absorption spectroscopies, respectively. Although microporous Pt and Au are not excellent electrodes in isolation, both metals exert a synergistic effect on the oxygen surface exchange rate in the presence of the mixed conducting film.

Preparation and characterization of epitaxially grown yttria-stabilized zirconia thin films on porous silicon substrates for solid oxide fuel cell applications

Epitaxial growth of yttria-stabilized zirconia (YSZ) thin film on through-hole-type porous silicon [tht-PSi(001)] with vertical pores penetrating from the surface to the back side of the Si(001) substrate was achieved. The in-plane and out-of-plane lattice parameters of YSZ thin film deposited on the tht-PSi(001) were, respectively 0.5167 and 0.5124 nm. Therefore, 0.54 % tensile strain was applied to the YSZ thin film. Also for this work, an all epitaxially grown thin film of YSZ/La0.7Sr0.3MnO3(LSMO)/CeO2/YSZ/Si(001) was prepared. The out-of-plane lattice parameter of YSZ was 0.5145 nm. Therefore, the YSZ thin film of YSZ/LSMO/CeO2/YSZ/Si(001) is almost relaxed, with a small amount of tensile strain (0.12 %). In-plane and out-of-plane electrical properties were measured respectively for YSZ/tht-PSi(001) and YSZ/LSMO/CeO2/YSZ/Si(001) thin films. Results show that ionic conduction was confirmed at 400 °C through constant electric conductivity against the change of oxygen partial pressure (pO2). Enhanced ionic conduction was observed for epitaxial YSZ/tht-PSi(001) thin films measured along the in-plane direction. Such enhanced ionic conduction was not observed for epitaxial YSZ/LSMO/CeO2/YSZ/Si(001) thin films measured along the out-of-plane direction. These findings suggest that enhanced ionic conduction is correlated with tensile strain in YSZ thin films.

Seasonality and Sex-Biased Fluctuation of Birth Weight in Tibetan Populations.

The online version contains supplementary material available at 10.1007/s43657-021-00038-7.

In Vitro Evaluation of Miniaturized Amperometric Enzyme Sensor Based on the Direct Electron Transfer Principle for Continuous Glucose Monitoring.

The bacterial derived flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase (FADGDH) is the most promising enzyme for the third-generation principle-based enzyme sensor for continuous glucose monitoring (CGM). Due to the ability of the enzyme to transfer electrons directly to the electrode, recognized as direct electron transfer (DET)-type FADGDH, although no investigation has been reported about DET-type FADGDH employed on a miniaturized integrated electrode. The miniaturized integrated electrode was formed by sputtering gold (Au) onto a flexible film with 0.1 mm in thickness and divided into 3 parts. After an insulation layer was laminated, 3 openings for a working electrode, a counter electrode and a reference electrode were formed by dry etching. A reagent mix containing 1.2 × 10-4 Unit of DET-type FADGDH and carbon particles was deposited. The long-term stability of sensor was evaluated by continuous operation, and its performance was also evaluated in the presence of acetaminophen and the change in oxygen partial pressure (pO2) level. The amperometric response of the sensor showed a linear response to glucose concentration up to 500 mg/dL without significant change of the response over an 11-day continuous measurement. Moreover, the effect of acetaminophen and pO2 on the response were negligible. These results indicate the superb potential of the DET-type FADGDH-based sensor with the combination of a miniaturized integrated electrode. Thus, the described miniaturized DET-type glucose sensor for CGM will be a promising tool for effective glycemic control. This will be further investigated using an in vivo study.

Correlation between changes in arterial blood oxygen partial pressure, oxygen uptake and carbon dioxide elimination by the lungs with changes in positive end expiratory pressure: a prospective observational study

INTRODUCTION: Since mechanical ventilation remains the main tool of respiratory support, ventilatory aspect of lung function fixed researchers’ attention during last decades, which is reflected by open lung concept and lung-protective ventilation strategy. However, it seems logical to assess function of the lung — biphasic mass exchanger with limited capacity — measuring its gas exchange performance, depending upon lung perfusion the same extent as ventilation. Recently clinicians have got routine access to metabolographers, providing figures of lungs oxygen absorption (VO2) and carbon dioxide exhalation (VCO2). OBJECTIVE: To evaluate interchangeability of metabolographer data and arterial blood gases analysis as tools for positive end-expiratory pressure (PEEP) titration by comparison of dynamic VO2 and VCO2 changes with PaO2 shifts after standardized PEEP changing. MATERIALS AND METHODS: A single-center prospective observational study included 41 patients underwent mechanical ventilation during general anesthesia for elective non-cardiothoracic surgery. After anesthesia induction and monitored parameters stabilization, PaO2, VCO2 and VO2 were measured before and after PEEP increasing from 2 to 5 mbar. Correlation was evaluated using Spearman coefficient in R-Studio with ggplot2 visualization package. RESULTS: After PEEP level increase, in 14 patients PaO2 changes were &lt; 5 %, in 15 patients PaO2 increase was observed, and in 12 patients PaO2 has decreased. The Spearman correlation coefficient (rh) between VCO2 and PaO2 was 0.77 (р-value = 3.75 × 10−9), between VO2 and PaO2 — rh = 0.92 (p-value = 2.2 × 10−16). CONCLUSIONS: The VCO2 and VO2 dynamic changes obtained using metabolographer demonstrates high correlation with PaO2 shifts followed PEEP changes, which makes the dynamic analysis of the first two indicators a possible non-invasive alternative for repeated arterial blood gases analysis during РЕЕР level titration. Notable fact is that in significant proportion of observations, PEEP level of 5 mbar, often recommended “by default” for lung-protective ventilation, is excessive from gas exchange performance point of view.

Characterizing perfusion defects in metastatic lymph nodes at an early stage using high-frequency ultrasound and micro-CT imaging.

A perfusion defect in a metastatic lymph node (LN) can be visualized as a localized area of low contrast on contrast-enhanced CT, MRI or ultrasound images. Hypotheses for perfusion defects include abnormal hemodynamics in neovascular vessels or a decrease in blood flow in pre-existing blood vessels in the parenchyma due to compression by LN tumor growth. However, the mechanisms underlying perfusion defects in LNs during the early stage of LN metastasis have not been investigated. We show that tumor mass formation with very few microvessels was associated with a perfusion defect in a non-enlarged LN at the early stage of LN metastasis in a LN adenopathy mouse (LN size circa 10 mm). We found in a mouse model of LN metastasis, induced using non-keratinizing tumor cells, that during the formation of the perfusion defect in a non-enlarged LN, the number of blood vessels ≤ 50μm in diameter decreased, while those of > 50μm in diameter increased. The methods used were contrast-enhanced high-frequency ultrasound and contrast-enhanced micro-CT imaging systems, with a maximum spatial resolution of > 30μm. Furthermore, we found no tumor angiogenesis or oxygen partial pressure (pO2) changes in the metastatic LN. Our results demonstrate that the perfusion defect appears to be a specific form of tumorigenesis in the LN, which is a vascular-rich organ. We anticipate that a perfusion defect on ultrasound, CT or MRI images will be used as an indicator of a non-enlarged metastatic LN at an early stage.

Application of Intelligent Monitoring of Percutaneous Partial Oxygen Pressure in Evaluating the Evolution of Scar Hyperplasia.

The study aimed to investigate the dynamic changes of percutaneous partial oxygen pressure during the development and evolution of a hypertrophic scar. Twenty cases of hypertrophic scar patients at different stages were selected. A percutaneous oxygen monitor was used to measure oxygen partial pressure in the scar and normal skin tissue at 14, 30, 60, and 90 days after surgery. The changes of oxygen partial pressure, tissue structure, HIF-1α, and VEGF expression in the scar tissue were observed, and the correlation was analyzed. In the scar maturation process, with the prolongation of time, the partial oxygen pressure in the tissue increased gradually. The expression intensity of HIF-1α and VEGF decreased gradually, HIF-1α was positively correlated with VEGF (r = 0.98, P < 0.01), there was a negative correlation between oxygen partial pressure and HIF-1 α expression (r = −0.92, P < 0.01), and it was negatively correlated with VEGF (r = −0.88, P < 0.01). TcPO2 measurement can be used to assess scar maturity; HIF-1 α and VEGF may play an essential role in regulating partial oxygen pressure in the scar tissue.

Impact of La doping on the thermochemical heat storage properties of CaMnO3-δ

Recently, CaMnO3 has been proposed as a promising candidate for high temperature thermochemical heat storage. The material reversibly releases oxygen in response to changes in oxygen partial pressure (pO2) in the temperature range (800-1000°C) suitable for Concentrated Solar Power (CSP) plants. However, it undergoes decomposition at pO2<0.008 atm and at temperature ≥ 1100°C, limiting its value. In this study, doping with La on the A-site (10 and 30 cat%) was explored as an approach for tuning thermochemical behavior (i.e. reaction enthalpy, reaction entropy, reaction extent, reduction onset temperature, and thermal stability). The thermodynamic properties were determined from mass loss measurements at selected pO2. Both 10 and 30 cat% La stabilized the base oxide against decomposition up to 1200°C at pO2=0.008 atm, providing access to higher operating temperatures. At 10 cat% La, both the reaction enthalpy and the reaction entropy increased, whereas both decreased at the 30 cat% doping level. The chemical heat storage capacity of Ca0.9La0.1MnO3 (~265 kJ/kgABO3) was found to be comparable to that of undoped CaMnO3, which is in turn much higher than that of Ca0.7La0.3MnO3 (~97 kJ/kgABO3) and slightly lower than was previously reported for CaMn0.9Fe0.1O3 under similar conditions. The differences between the heat storage capacities of these materials can be fully understood in terms of the differences in the enthalpies and entropies of reduction. Entropy is not a metric usually considered when estimating the thermochemical storage capacity of a material, but it is an essential property because, as discussed here, the reaction extent depends monotonically on this term. Accordingly, materials with large entropy of reduction and intermediate enthalpy of reduction, where the latter metric represents a compromise between the heat per mole of reacted oxide and reaction extent, are desirable for chemical heat storage applications.

Elevational niche-shift migration: Why the degree of elevational change matters for the ecology, evolution, and physiology of migratory birds

Abstract Elevational migration can be defined as roundtrip seasonal movement that involves upward and downward shifts in elevation. These shifts incur physiological challenges that are proportional to the degree of elevational change. Larger shifts in elevation correspond to larger shifts in partial pressure of oxygen, air density, temperature, and ultraviolet (UV) exposure. Although most avian examples of elevational migration involve subtle shifts that would have minimal impacts on physiology, shifts of any magnitude have previously been considered under the broad umbrella of “elevational migration”. Here, we consider extreme seasonal elevational movements (≥2,000 m), sufficient to shift the elevational dimension of the eco-climatic niche. Migratory bird populations typically maintain inter-seasonal stability in the temperature, precipitation, and elevational aspects of their climatic niches, a tendency that likely reflects genetic physiological specialization on environmental conditions such as atmospheric pressure. A shift of ≥2,000 m involves a ≥20% change in air density and oxygen partial pressure, sufficient to incur functionally impactful declines in arterial blood-oxygen saturation and require compensatory shifts in respiratory physiology. We refer to this phenomenon as elevational niche-shift migration (ENSM). In this review, we analyzed &amp;gt;4 million occurrence records to identify 105 populations, representing 92 bird species, that undergo complete or partial ENSM. We identified key ecological and evolutionary questions regarding the causes and consequences of ENSM. Our synthesis reveals that ENSM has evolved independently in at least 29 avian families spanning 10 orders. Nonetheless, ENSM is rare relative to other forms of seasonal migration, consistent with the general tendency of seasonal niche conservatism by migratory species and evolutionarily conserved elevational range limits. For many migratory species and populations, within-species patterns of migratory connectivity are not sufficiently understood to determine ENSM status. ENSM is distinguished by its scale within the broader phenomenon of elevational migration. Critical examination of ENSM illustrates fundamental constraints on the ecology and evolution of migration systems, topographical influences on geographic patterns of migratory connectivity, and the remarkable metabolic flexibility of certain bird species that allows them to occupy disparate elevations across different seasons.

Development of Liver Normothermic Machine Perfusion Repair and Assessment System

This paper introduced a liver normothermic machine perfusion repair and assessment system. This system consists of a liver normothermic machine perfusion device, a fluorescence imaging system and a tissue oxygen detector. The normothermic machine perfusion device can continuously perfuse the donor liver and monitor and control the perfusion parameters in real time. The fluorescence imaging system can detect the indocyanine green metabolized by the liver to evaluate the microcirculation and the metabolism function of hepatocytes. The tissue oxygen detector can monitor the change of oxygen partial pressure of liver tissue in real time to evaluate the state of cell oxygen consumption.

Estimation of mercury and zinc concentration in the vapour phase by measuring oxygen partial pressure

Indirect on-line estimation of metal vapours of Hg and Zn using YSZ based electrochemical oxygen sensor is attempted. Change in oxygen partial pressure, in presence and absence of these metals vapours, enables the estimation by using oxygen sensor. Using this method, the Zn metal vapours has been detected down to 13.3 ± 0.7 vppm and for Hg vapour, the lowest detection limit is 68.1 ± 0.7 vppm. The measured vapour pressure is in agreement with the predicted values.