Pump Oxygenator Research Articles

Oxygen equilibration kinetics of mixed-conducting perovskites BSCF, LSCF, and PSCF at 900 °C determined by electrical conductivity relaxation

For an application of mixed ionic-electronic conducting (MIEC) perovskite oxides, e.g., as solid oxide fuel cell (SOFC) cathodes, as high-temperature gas sensors or as oxygen-transport membrane (OTM) materials, the kinetics of oxygen transport is of fundamental importance.A common setup for the determination of the chemical diffusion coefficient Dδ and the surface exchange coefficient kδ is the electrical conductivity relaxation (ECR) method where the conductivity response of an MIEC sample is measured after the ambient oxygen partial pressure pO2 has been abruptly changed using different gas mixtures. In the present study, however, a closed tubular zirconia “oxygen pump” setup was used which facilitates precise pO2 control in a closed sample space with a high resolution at temperatures above 700°C in atmospheres ranging from pure oxygen continuously down to pO2=10−18bar. Reasonably fast pO2 changes enable an application of the ECR technique on MIEC oxides down to lower partial pressures not easily accessible with gas mixtures.The oxygen transport parameters of dense ceramic bulk samples of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF), and Pr0.58Sr0.4Co0.2Fe0.8O3-δ (PSCF) have been studied as a function of temperature (800 and 900°C) in the range between 10−6≤pO2/bar≤0.21. The Dδ and kδ values obtained for LSCF at 800°C are in good agreement with values from literature, proving the usability of the setup for ECR measurements. For BSCF, LSCF, and PSCF, Dδ and kδ values could be determined for the first time at 900°C as a function of pO2.

Abstract 18046: Emergency Coronary Artery Bypass Grafting for Cardiogenic Shock Complicating Acute Myocardial Infarction is Associated With Satisfactory Long-term Outcomes in Hospital Survivors

Introduction: Cardiogenic shock (CS), which is one of the most dreadful complications following acute myocardial infarction (AMI), is an indication for emergent coronary artery bypass graft surgery (CABG) in patients not amenable for percutaneous coronary intervention. Our study aimed to identify risk factors for 30-day and long-term mortality in patients presenting with AMI complicated by CS requiring emergency CABG. Methods: Preoperative characteristics, operative parameters, and postoperative outcomes were prospectively collected for 508 patients undergoing CABG for CS complicating AMI (ST-elevation MI [STEMI]:42.9%;non-STEMI:57.1%) in our database between January 2000 and June 2014. Predictors of 30-day and long-term mortality were identified by logistic and Cox regression analyses, respectively. Results: Mean age was 69±10 years. 78.3% of patients had 3-vessel and 47% left main disease. Almost 50% of patients had left ventricular function <30% with 29.6%, 37.9%, 46.7% and 9.8% requiring preoperative resuscitation, ventilator, intra-aortic balloon pump and extracorporeal membrane oxygenation support (ECMO), respectively. 30-day mortality was 31.9% and was independently predicted by peripheral vascular disease [PVD] (odds ratio [OR]:1.8; 95% confidence interval [CI]:1.1-2.9;p=0.02), STEMI (OR:1.9;95%CI:1.2-2.8;p=0.004), lactate levels >4mmol/l (OR:3.3;95%CI:1.7-6.5;p<0.0001) and ECMO support (OR:5.0;95%CI:2.6-9.9;p<0.0001). Cumulative survival was 51% at 1 year, 44% at 3 years and 33% at 5 years and correspondingly improved to 74%, 64% and 48%, when 30-day mortality was excluded from the analysis. Incremental age (OR:1.04,p<0.0001), STEMI (OR:1.3,p=0.02), PVD (OR:1.4,p=0.03), diabetes (OR:1.5,p=0.001), lactate levels >4mmol/l (OR:2.3,p<0.0001) and high preoperative inotropic (OR:1.3,p=0.02), and ECMO support (OR:3.3,p<0.0001) predicted late mortality. Conclusion: Emergency CABG in patients with AMI complicated by CS was associated with high 30-day mortality, which was independently predicted by severe preoperative hemodynamic instability and presence of STEMI. Satisfactory long-term survival is observed in patients who survived the operation, demonstrating the benefit of emergency CABG.

Oxygen pump based on stabilized zirconia.

When a DC voltage is applied across a zirconia ceramic layer, an electrical field is established to drive oxygen species through the layer. Taking advantage of this electrochemical phenomenon, we have designed and developed an oxygen pump that offers continuously adjustable oxygen partial pressure from 1 bar down to 10(-24) bar in the temperature range of 650-1100 °C. Demonstrated with electrical conductivity measurements on Fe-doped SrTiO3, these excellent capabilities of the oxygen pump are valuable for investigations on the defect chemistry of electroceramics.

Effects of additives on RuO2(10 wt%)/La0.6Sr0.4CoO3 anode for increasing sensitivity of solid oxide amperometric CO Sensor

An amperometric CO sensor using a solid oxide electrolyte was studied and it was found that the oxygen pumping current increased with increasing CO concentration when Au(10wt%)/In1.9Sn0.1O3 and RuO2(10wt%)/La0.6Sr0.4CoO3(LSC) were used for cathode and anode, respectively and La0.9Sr0.1Ga0.8Mg0.2O3 as the electrolyte. Changes in oxygen pumping current was caused by difference in electrode activity to CO oxidation upon exposure to CO and so sensitivity is strongly dependent on difference in electrode activity. Effects of additives to RuO2/LSC electrode on CO sensitivity were studied and it was found that addition of Pt is highly effective for increasing CO sensitivity. This could be explained by increased oxidation activity to CO. Further addition of Pd as the second additive to Pt–RuO2/LSC was effective for achieving high sensitivity and the highest CO sensitivity in our previous study was achieved on this type sensor. Amperometric sensor using RuO2–PtPd/LSC and Au/ITO anode and cathode, respectively, shows the high sensitivity to CO and so this sensor is promising as a CO sensor directly inserted into exhaust gas.

Limiting oxidation of ZrB2 by application of an electric field across its oxide scale

The purpose of this study was to develop a method to improve the oxidation resistance of ZrB2 ceramics used in Ultra High Temperature (UHT) applications. This was achieved by limiting oxygen ion diffusion through the zirconia scale by the application of an electric field while performing an oxidation test at 1400 °C in air for 5 h. The electric field (voltage <10 V) applied across the growing oxide layer (where the ZrB2 sample was at a lower potential with respect to the surface electrode) was sufficient to nearly completely arrest oxidation. By application of an electric field, the growth of the oxide scale was reduced by 800% if compared to the case without field. This is a novel approach to increase the potential operating temperature of many materials operating in an oxygen containing environment, without compromising any of their other properties. The measured voltage and current suggest the mechanism can be explained by oxygen pumping theoretically described by the Nerst equation.

Spontaneous Oxidation of Ni Nanoclusters on MgO Monolayers Induced by Segregation of Interfacial Oxygen.

We report the study of Ni nanoclusters deposited on MgO/Ag(100) ultrathin films (one monolayer) at T = 200 K. We show by STM analysis and DFT calculations that in the limit of low Ni coverage the formation of nanoclusters of four to six atoms occurs and that these aggregates are flat rather than 3D, as expected for Ni tetramers, pentamers, or hexamers. Both the shape of the clusters and the interatomic distance between neighboring Ni atoms are indicative that the nanoparticles do not consist of pure metal atoms but that a NiyOx structure has formed thanks to the availability of atomic oxygen accumulated at the MgO/Ag interface, with Ni clusters acting as oxygen pumps. Besides being of relevance in view of the use of metal nanoclusters in catalysis and other applications, this finding gives a further proof of the peculiar behavior of ultrathin oxide films.

Electrochemical Separation, Pumping, and Storage of Hydrogen or Oxygen into Nanocapillaries Via High Pressure MEA Seals

High-density storage of gases remains a major technological hurdle for many fields. The U.S. Department of Energy (DOE), for example, reduced their hydrogen storage targets for automotive applications due to the inability of technologies to reach the system-level targets.1 Without significant improvements in hydrogen storage density, hydrogen as a transportation fuel remains unfeasible. In other fields, the low volumetric and gravimetric storage densities of oxygen gas cylinders can be cumbersome or prohibitively expensive for applications like terrestrial and marine breathing apparatus’ or manned space exploration. Emerging technologies such as sorbents and chemical complexes show potential for gas storage. However, the ability to achieve application-specific gas delivery rates and high storage densities, while operating reversibly at ambient temperature, remains elusive.2, 3 In contrast, it may be possible to achieve high gas storage densities and potentially high gas delivery rates using nanocapillaries when used in conjunction with a membrane electrode assembly (MEA). Hoop stress calculations show that the pressure tolerances of cylinders are inversely proportional to the radius. Indeed, glass microcapillaries have already theoretically4 and experimentally5 demonstrated the capacity to achieve DOE hydrogen storage targets at a materials-level. This technology can be further improved by reducing the capillary radius to the nanoscale; however, the capping and pressurization of the gas in micro- or nanocapillaries remains problematic. Presented here is the fabrication of nanocapillary arrays capped by an MEA for highly reversible storage of gases with the potential for high rate pumping and high-density storage. Very high aspect ratio and densely packed nanocapillary arrays are produced through aluminum anodization. The nanocapillary arrays are capped with either a PEM or an alkaline (anion) exchange membrane (AEM) complete with catalyst nanoparticles on either side of the membrane to form an MEA. This MEA is used to provide controllable electrochemical pumping of hydrogen or oxygen gas into and out of the nanocapillaries. The MEA also serves as a high pressure seal. A theoretical discussion of the potential volumetric and gravimetric storage densities of hydrogen and oxygen in nanocapillary arrays will be presented together with experimental results of electrochemical gas compression into lab-scale devices. The evaluation of both commercial catalyst materials and fabricated nanoparticle catalysts (<10 nm) for hydrogen and oxygen pumping will be discussed. In addition, the performance of both PEM and AEM for electrochemical pumping of oxygen will be compared. A discussion of the electrochemistry within nanocapillaries compared to planar MEAs will be given including the charge transport/transfer processes. The potential failure mechanisms and the technical obstacles to the implementation of our electrochemical membrane approach, together with the current state of the technology and overall storage capacities, will be presented. 1. Hydrogen, Fuel Cells and Infrastructure Technologies Program: Multi-Year Research, Development and Demonstration Plan. US Department of Energy, Energy Efficiency and Renewable Energy 2012. 2. Zhou, L., Progress and problems in hydrogen storage methods. Renewable and Sustainable Energy Reviews 2005, 9 (4), 395-408. 3. Pukazhselvan, D.; Kumar, V.; Singh, S., High capacity hydrogen storage: basic aspects, new developments and milestones. Nano Energy 2012, 1 (4), 566-589. 4. Zhevago, N.; Glebov, V., Hydrogen storage in capillary arrays. Energy Conversion and Management 2007, 48 (5), 1554-1559. 5. Zhevago, N.; Denisov, E.; Glebov, V., Experimental investigation of hydrogen storage in capillary arrays. International Journal of Hydrogen Energy 2010, 35 (1), 169-175.

Zirconia-Based Electrochemical Oxygen Sensor to Infer Fuel Ethanol Content in Flex Fuel Vehicles

Zirconia-based electrochemical sensors for measuring the oxygen concentration in the automotive exhaust have been used on vehicles for many years. The oxygen sensor is an electrochemical cell based on oxygen-ion conducting zirconia. The sensor consists of a single electrochemical cell which has one electrode exposed to a reference (air) atmosphere and the other electrode exposed to the measurement (exhaust) gas. This sensor operates as a simple Nernst cell. The open circuit voltage of this zirconia electrochemical cell changes with variations in the oxygen partial pressures (pO2) existing adjacent to its two electrodes. Since the reference electrode is maintained at a constant pO2 (air), the emf generated by this Nernst cell gives a measurement of the concentration of oxygen in the exhaust gas. All gasoline (and some diesel) vehicles currently utilize an oxygen sensor to control their emission systems. Although successfully used for stoichiometric air-to-fuel (A/F) control for many years, these Nernst-type oxygen sensors are not useful for applications away from stoichiometry because of their low sensitivity. The Nernst cell has a logarithmic dependence of the emf on oxygen partial pressure. More recently, double zirconia-cell sensors have been developed which have much higher sensitivity and therefore a wider range of operation. These “wide-range oxygen” or “universal exhaust gas oxygen” (UEGO) sensors are applicable to A/F measurement and control from very rich to very lean A/F mixtures. These double-cell sensors are based on oxygen pumping, which involves the transfer of oxygen from one side of a zirconia cell to the other by passing an electric current through the device. Most new vehicles, as well as an increasing number of diesel powertrains, employ UEGO sensors to meet the ever-stricter emission requirements mandated by law. A novel method has been developed to use this double-cell oxygen-pumping device (UEGO sensor) to measu­re the concentration of other oxygen containing molecules in the exhaust gas, e.g. H2O, CO2, SO2, and NOx. In order to mea­sure these oxygen containing species, a voltage that is greater than the dissociation potential for a particular measurement species is applied across the cell. The dissociated species contributes oxygen that can now be measured by the sensor. The output of the cell provides a measure of the oxygen generated from the decomposition of the measurement gas, and thus a measure of its concentration. In the exhaust gas this measurement is complicated by the fact that oxygen, along with other oxygen-containing molecules, is also present. If the relative amounts of these other molecules were constant, then the concentration of the measurement species could still be determined unambiguously by subtracting the contribution of these other molecules. However, the amounts of the different oxygen-containing molecules in the exhaust gas may vary with engine operating conditions. This uncertainty can be resolved by applying differing dissociation potentials across the cell. The output of the sensor at each potential then provides a measurement of the amount of oxygen containing species with dissociation potential less than the applied potential. Subtracting the signals can discriminate between the various constituents. For example in a mixture of air and water, the oxygen concentration alone can be determined by measuring the output of the sensor with a low potential applied. Then the measurement of the concentration of oxygen plus water can be measured by subsequently applying a voltage larger than the dissociation potential of water. The water concentration can be determined by subtracting the signal due to oxygen from the signal due to the combination of the gases. In principle, these measurements can be achieved without any modification to the existing sensor hardware. A simple modification to the electronic control circuitry is all that is required to perform this type of measurement. Figure 1 shows the sensitivity of a commercially available UEGO sensor for the dissociation of H2O as a function of dissociation potential. A typical operating value for the sensing voltage (Vs) for oxygen measurement is 450 mV. The plot below was generated from data measured in the lab at various water concentrations in a carrier gas of dry air. From the plot it is evident that water dissociation is occurring at potentials greater than 800 mV. Additionally, the output begins to saturate at a potential approaching 1100 mV, suggesting that full dissociation of the water has been achieved. Several vehicle applications for measuring the water concentration in the exhaust will be discussed including ambient humidity measurement and ethanol concentration in gasoline mixtures for flex fuel vehicles. In addition, carbon dioxide measurements will also be discussed. Figure 1

50th Anniversary Landmark Commentary on Lillehei CW, Varco RL, Cohen M, Warden HE, Patton C, Moller JH. The first open-heart repairs of ventricular septal defect, atrioventricular communis, and tetralogy of Fallot using extracorporeal circulation by cross-circulation: a 30-year follow-up. Ann Thorac Surg 1986;41:4–21

This index article by Dr C. Walton Lillehei, and colleagues describes the 30-year outcomes in patients who underwent repair of congenital heart defects at the University of Minnesota with the use of cross-circulation between parent and patient [1]. The article and discussion contain important lessons for cardiothoracic surgeons. First, the article highlights the importance of innovation based on extensive laboratory research. The use of the parent as the “pump oxygenator” followed years of animal laboratory experience, particularly the observation of improved survival with low-flow cross-circulation compared with early pump oxygenators.

Binder Jetting: A Novel Solid Oxide Fuel-Cell Fabrication Process and Evaluation

With an ever-growing concern to find a more efficient and less polluting means of producing electricity, fuel cells have constantly been of great interest. Fuel cells electrochemically convert chemical energy directly into electricity and heat without resorting to combustion/mechanical cycling. This article studies the solid oxide fuel cell (SOFC), which is a high-temperature (100°C to 1000°C) ceramic cell made from all solid-state components and can operate under a wide range of fuel sources such as hydrogen, methanol, gasoline, diesel, and gasified coal. Traditionally, SOFCs are fabricated using processes such as tape casting, calendaring, extrusion, and warm pressing for substrate support, followed by screen printing, slurry coating, spray techniques, vapor deposition, and sputter techniques, which have limited control in substrate microstructure. In this article, the feasibility of engineering the porosity and configuration of an SOFC via an additive manufacturing (AM) method known as binder jet printing was explored. The anode, cathode and oxygen ion-conducting electrolyte layers were fabricated through AM sequentially as a complete fuel cell unit. The cell performance was measured in two modes: (I) as an electrolytic oxygen pump and (II) as a galvanic electricity generator using hydrogen gas as the fuel. An analysis on influence of porosity was performed through SEM studies and permeability testing. An additional study on fuel cell material composition was conducted to verify the effects of binder jetting through SEM–EDS. Electrical discharge of the AM fabricated SOFC and nonlinearity of permeability tests show that, with additional work, the porosity of the cell can be modified for optimal performance at operating flow and temperature conditions.

Effect of neoadjuvant pelvic perfusion on symptom control and resection of pelvic recurrent rectal cancer.

723 Background: Isolated pelvic perfusion (IPP) may improve disease control and facilitate pelvic resection in selected high-risk patients with advanced recurrent rectal cancer by reducing painful tumor burden and lessening chances of recurrence. Methods: IPP was done in 42 patients with locally advanced previously irradiated rectal cancer, 26 as preoperative therapy and 16 for palliation. A comparative larger non-perfused group included 63 patients with pelvic resection only via abdominal sacral resection (ABSR) for recurrent rectal cancer. Isolated pelvic perfusion (IPP) with a pump oxygenator, (temp &gt; 41ºc), delivered sequential (q 10 minutes) chemotherapy:– 5FU (5fluorouracil) 1,500 mg/m2, cisplatin/oxaliplatin 100/150 mg/m2, mitomycin 10mg/m2, for 60 minutes in 42 patients. Results: Palliative IPP in 16 advanced rectal cancer patients resulted in significant relief (1–4 months) of narcotic resistant pain (in 70%). Pre-operative IPP in 26 locally advanced rectal cancer patients achieved a clinical path (CR) in 2 patients, and significant regression in 11 patients rendering them resectable. Seven had RO pelvic resections. Of 6 other patients, 4 refused surgery, 2 were medically excluded. Median survival was 30 months in 7 resected patients (all had RO resections) and 2 were 5-year survivors. This is compared to outcome in 63 patients having pelvic resection alone for recurrence: 57 % had RO resection (median OS = 36 months), 28% had R1 resection (median OS = 15 months) and 15% had R2 resection (marrow invasion) (median OS = 21 months). Conclusions: Neoadjuvant IPP may facilitate resection of advanced or (borderline resectable) recurrent rectal cancer by reducing tumor bulk and identifying therapeutic responders likely to benefit from major pelvic resection while excluding non-responders mostly likely to benefit from non-surgical therapy. The potential to induce regression and facilitate RO resection merits further exploration

History of pediatric cardiology in India

In India, the discipline of cardiology started in the late 1950s and at that time pediatric cardiology was practiced as a part of cardiology specialty. This article traces the history of pediatric cardiology in India. Dr. S. Padmawati and Dr. Kamala Vytilingam underwent training in pediatric cardiology at international centers in the early 1950s and early 1960s. Dr. N. Gopinath successfully closed a ventricular septal defect using a pump oxygenator at Christian Medical College, Vellore. Open heart surgery program kicked off in the 1960s with the tireless efforts of many other surgeons. Dr. Rajendra Tandon, trained for 2 years at Boston Children Hospital under Dr. Alexander Nadas, joined the Department of Cardiology at the All India Institute of Medical Sciences, New Delhi in 1963. This and many other stories are described.

Characterization of oxygen-dependent stability of selected mixed-conducting perovskite oxides

For high-temperature energy applications, e.g., as solid oxide fuel cell cathodes or as dense ceramic oxygen-transport membranes, mixed ionic-electronic conducting (MIEC) perovskites, namely of the composition (AxSr1−x)(CoyFe1−y)O3−δ (A=La, Pr, Ba), are promising candidates given their excellent oxygen-ionic and electronic transport properties. A high level of oxygen non-stoichiometry is an important prerequisite for a high performance; however, the structural stability of the oxide is also affected by oxygen deficiency.By coulometric titration experiments performed on selected state-of-the-art MIEC powder samples in a tubular zirconia “oxygen pump” setup, facilitating precise control of the oxygen partial pressure in the entire range between pO2=10−18…1bar at temperatures between 700…1000°C, the low-pO2 stability limits can be determined. By monitoring the electrical current necessary for pumping oxygen through the solid electrolyte into or out of the measurement chamber, the amount of oxygen transported and, thus, changes in oxygen stoichiometry can be determined. The low-pO2 stability limits for all investigated high-performance MIEC oxides were similar (below 10−10bar at 900°C).

CFD-modeling of processes in a high-pressure oxidizer pump for the turbopump assembly of a liquid rocket engine

The article presents CFD modeling of the work process in the oxidizer pump of a turbopump assemblyusing the ANSYS CFX software, as well as the comparison of numerical and theoretical calculations of theanalytical relations based on geometric data. Problems were encountered when modeling the flow of the pumpdue to inaccuracies in the drawing. The spherical radius in the area of the volute chamber throat had to bereduced, otherwise the model would not be topologically consistent with the original. The data on the vaneangles at the inlet and outlet of the centrifugal impeller were absent in the drawings. The blade angles weredetermined by the previously constructed geometric model. Negative pressure at the entrance of the impellervanes was found in the analysis of the first results of CFD-calculation. Increasing the number of elements in thispart of the calculation model made it possible to reduce the area of the negative pressure.CFD-modeling error with respect to the analytical solution does not exceed 11% by the parameters of total andstatic pressure. The results of the work can provide a visual representation of the processes taking place duringthe operation of the high-pressure pump of a turbopump assembly. The CFD-model can also be used for furtherresearch of work processes in liquid oxygen pumps to reduce the number of development tests.

A quinol oxidase, encoded by cyoABCD, is utilized to adapt to lower O2 concentrations in Rhizobium etli CFN42.

Bacteria have branched aerobic respiratory chains that terminate at different terminal oxidases. These terminal oxidases have varying properties such as their affinity for oxygen, transcriptional regulation and proton pumping ability. The focus of this study was a quinol oxidase encoded by cyoABCD. Although this oxidase (Cyo) is widespread among bacteria, not much is known about its role in the cell, particularly in bacteria that contain both cytochrome c oxidases and quinol oxidases. Using Rhizobium etli CFN42 as a model organism, a cyo mutant was analysed for its ability to grow in batch cultures at high (21 % O2) and low (1 and 0.1 % O2) ambient oxygen concentrations. In comparison with other oxidase mutants, the cyo mutant had a significantly longer lag phase under low-oxygen conditions. Using a cyo :: lacZ transcriptional fusion, it was shown that cyo expression in the wild type peaks between 1 and 2.5 % O2. In addition, it was shown with quantitative reverse transcriptase PCR that cyoB is upregulated approximately fivefold in 1 % O2 compared with fully aerobic (21 % O2) conditions. Analysis of the cyo mutant during symbiosis with Phaseolous vulgaris indicated that Cyo is utilized during early development of the symbiosis. Although it is commonly thought that Cyo is utilized only at higher oxygen concentrations, the results from this study indicate that Cyo is important for adaptation to and sustained growth under low oxygen.

Insensible water loss through adult extracorporeal membrane oxygenation circuit: an in vitro study.

Patients on extracorporeal membrane oxygenation (ECMO) are critically ill, and fluid balance need to be managed as accurately as possible. Previous studies have focused on insensible water loss through neonatal ECMO circuit and showed that water loss through the ECMO circuit was correlated with the sweep-gas flow rates. Current study is the first study focusing on insensible water loss through adult ECMO circuit. An in vitro extracorporeal circuit consisting of Jostra Quadrox D membrane oxygenator and centrifugal pump was primed with normal saline. The amount of water loss through the ECMO circuit was found to be linearly correlated with the sweep-gas flow rate and fluid temperature. For every liter per minute of sweep-gas flow at 37°C, 0.046 ml/min of water will be lost, and for every change of fluid temperature by 1°C, water content loss will be changed by 0.0026 ml/min by multiple linear regression (R = 0.996). The average daily water loss for every liter per minute of sweep-gas flow at 33, 34, 35, 36, 37, 38, and 39°C were 51.3, 55, 58.8, 62.5, 66.2, 70.0, and 73.7 ml/day, respectively.

Control of dissolved oxygen in liquid LBE by electrochemical oxygen pumping

Electrochemical oxygen pumping method was applied in order to control the dissolved oxygen concentration in liquid lead–bismuth eutectic (LBE). The oxygen pump was fabricated using yttria partially stabilized zirconia (YPSZ) as a solid electrolyte and LSM (strontium-doped lanthanum manganite)–GDC (gadolinium-doped ceria) composite as a cathode. An oxygen control system, comprising of the oxygen pump, an oxygen sensor and a DC current source as well as a proportional-integral-derivative (PID) controller for the current control, was applied to regulate the dissolved oxygen concentration in liquid LBE. Highly accurate control of the oxygen concentration was achieved by this system. In addition, the feasibility of using the pumping system for measuring corrosion kinetics of structural steels in liquid LBE was demonstrated.

Optically (solar) pumped oxygen-iodine lasers

We present the results of theoretical and experimental studies demonstrating the possibility of developing an oxygen-iodine laser (OIL) with direct optical pumping of molecular oxygen involving inter-molecular interaction with charge transfer from donor molecule (buffer gas) to acceptor molecule (oxygen). This interaction lifts degeneracy of the lower energy states of molecular oxygen and increases its absorption cross section in the visible spectral region and the UV Herzberg band, where high quantum yield of singlet oxygen is achieved (QY ∼ 1 and QY ∼ 2, respectively) at the same time. A pulse-periodic optical pump sources with pulse energy of ∼50 kJ, pulse duration of ∼25 μs, and repetition rate of ∼10 Hz, which are synchronized with the mechanism of singlet oxygen generation, are developed. This allows implementation of a pulse-periodic oxygen-iodine laser with an efficiency of ∼25%, optical efficiency of ∼40%, and parameter L/T ∼ 1/1.5, where T is the thermal energy released in the laser active medium upon generation of energy L. It is demonstrated that, under direct solar pumping of molecular oxygen, the efficiency parameter of the OIL can reach L/T ∼ 1/0.8 in a wide range of scaling factors.

What Is The Evidence For Oxygenated Hypothermic Machine Perfusion in Kidney Transplantation? A Systematic Review*.

As the increasing demand for organs continues high risk donors represent an additional supply of organs to the donor pool. We systematically reviewed the evidence of ex-vivo hypothermic OMP in kidney donors. We searched Medline, Embase, Cochrane's CENTRAL and Transplant Library for human and animal studies on OMP alone or OMP compared with machine perfusion (MP) in kidney transplantation. Studies had to report patient/animal survival, discard rate, technical complications or renal function. Data were extracted regarding donors/recipients, oxygenation method, preservation time, perfusion temperature/pressure/flow, and outcomes. The search identified 2820 references of which 35 (18 case series, 11 cohort studies, 6 randomised controlled trials) met our inclusion criteria. Four studies were in humans and 31 in animals of which 20 were studies of auto-transplantation. Twelve animal studies in pigs (4), dogs (3), rats (4), and rabbits (1) compared OMP with MP and 23 studies in humans (4), pigs (5), dogs (11) and rats (3) reported on OMP alone. Seven methods of oxygenation were reported: ultrabaric oxygenation, membrane oxygenation, air pump oxygenation, retrograde persufflation, oxygenated persufflation, oxygenated machine perfusion and hyperbaric oxygenation/chamber. OMP was applied either continuously (8 studies) or at the end of the perfusion (27 studies). Perfusion temperature ranged 2-32°C and perfusion time 1-72 hours. There was one direct comparison of OMP and MP in pigs that reported on animal survival which showed rates of 100% for OMP versus 43% for MP. Two other studies (dogs, rats) showed survival rates of 0-100% for OMP and 0-80% for MP. Studies comparing OMP with MP showed conflicting results for renal function. There were no human trials comparing OMP with MP. Studies on OMP alone in humans showed patient survival rates of 50-100% (3 studies). OMP in animals led to survival rates of 0-100% (15 studies) with porcine studies showing survival rates of 33-100% (4 studies). The available evidence for oxygenated hypothermic machine perfusion is poor. There is inconclusive evidence that supplemental oxygenation during HMP improves early renal function. There is very little information from human studies. Thus good quality randomised controlled trials are essential to establish the role of oxygenation with machine perfusion. *Conducted as part of the Consortium for Organ Preservation in Europe (COPE), which is funded by an EU FP7 grant.

Polycrystalline Tetragonal Zirconia of the Form &lt;i&gt;ZrO&lt;sub&gt;2&lt;/sub&gt;: 3 mol% Re&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; &lt;/i&gt;(Re-TZP) for Use in Oxygen Sensors: Synthesis, Characterization and Ionic Conductivity

Oxygen ion conductors of zirconia based ceramics are a class of materials with technological applications in several application areas: sensors of chemical species, oxygen pumps, solid oxide fuel cells among others [1]. For these applications, the zirconia must possess the fluorite type crystal structure, or close to it. Such oxides with this structure are the classic oxygen ion conductors [2]. The fluorite structure consists of a cubic lattice of oxygen ions surrounded by cations. The cations are arranged in a face centered cubic structure with anions occupying tetrahedral positions. This leads to an open structure with large empty octahedral interstices.