Effects of Oxygen Partial Pressure and Substrate Temperature on the Structure and Morphology of Sc and Y Co-Doped ZrO2 Solid Electrolyte Thin Films Prepared via Pulsed Laser Deposition

Scandium (Sc) and yttrium (Y) co-doped ZrO2 (ScYSZ) thin films were prepared on a SiO2-Si substrate via pulsed laser deposition (PLD) method. In order to obtain good quality thin films with the desired microstructure, various oxygen partial pressures (PO2) from 0.01 Pa to 10 Pa and substrate temperatures (Ts) from 25 °C to 800 °C were investigated. X-ray diffraction (XRD) patterns results showed that amorphous ScYSZ thin films were formed at room substrate temperature while cubic polycrystalline thin films were obtained at higher substrate temperatures (Ts = 200 °C, 400 °C, 600 °C, 800 °C). Raman spectra revealed a distinct Raman shift at around 600 cm−1 supporting a cubic phase. However, a transition from cubic to tetragonal phase can be observed with increasing oxygen partial pressure. Photoemission spectroscopy (PES) spectra suggested supporting analysis that more oxygen vacancies in the lattice can be observed for samples deposited at lower oxygen partial pressures resulting in a cubic structure with higher dopant cation binding energies as compared to the tetragonal structure observed at higher oxygen partial pressure. On the other hand, dense morphologies can be obtained at lower PO2 (0.01 Pa and 0.1 Pa) while more porous morphologies can be obtained at higher PO2 (1.0 Pa and 10 Pa).

Feasıbılıty of Transcutaneous Method for Carbon Dıoxıde Monıtorıng in an Intensive Care Unıt

Background: Transcutaneous partial pressure of carbon dioxide (PtCO2) monitorization provides a continuous and non-invasive measurement of partial pressure of carbon dioxide (pCO2). In addition, peripheral oxygen saturation (SpO2) can also be measured and followed by this method. However, data regarding the correlation between PtCO2 and arterial pCO2 (PaCO2) measurements acquired from peripheric arterial blood gas is controversial. Objective: We aimed to determine the reliability of PtCO2 with PaCO2 based on its advantages, like non-invasiveness and continuous applicability. Methods: Thirty-five adult patients with hypercapnic respiratory failure admitted to our tertiary medical intensive care unit (ICU) were included. Then we compared PtCO2 and PaCO2 and both SpO2 measurements simultaneously. Thirty measurements from the deltoid zone and 26 measurements from the cheek zone were applied. Results: PtCO2 could not be measured from the deltoid region in 5 (14%) patients. SpO2 and pulse rate could not be detected at 8 (26.7%) of the deltoid zone measurements. Correlation coefficients between PtCO2 and PaCO2 from deltoid and the cheek region were r: 0,915 and r: 0,946 (p = 0,0001). In comparison with the Bland-Altman test, difference in deltoid measurements was -1,38 ± 1,18 mmHg (p = 0.252) and in cheek measurements it was -5,12 ± 0,92 mmHg (p = 0,0001). There was no statistically significant difference between SpO2 measurements in each region. Conclusion: Our results suggest that PtCO2 and SpO2 measurements from the deltoid region are reliable compared to the arterial blood gas analysis in hypercapnic ICU patients. More randomized controlled studies investigating the effects of different measurement areas, hemodynamic parameters, and hemoglobin levels are needed.

Distribution of current density across the active area at various stoichiometry ratios using the JRC ZERO∇CELL single cell PEM fuel cell testing hardware

The performance of the PEM fuel cell directly depends on the partial pressure of provided reactants, namely hydrogen and oxygen. Since reactants are consumed in the fuel cell reaction, partial pressure of reactants decreases in the direction of reactants flow. This well-known mechanism makes the performance of the fuel cell dependent on the stoichiometry ratios of input reactants. The JRC ZERO∇CELL, a single cell PEM fuel cell testing setup, is developed to provide as much as possible uniform operating conditions at the 10cm2 active area specimen, hence giving uniform current density across the active area of the cell. To investigate what is the real gradient of current density across the active area for the JRC ZERO∇CELL at various reactant stoichiometry ratios, segmented bi-polar plates and current collectors are developed. This study presents experimental investigation of the current density distribution across the active area of the JRC ZERO∇CELL setup at range of reactant stoichiometry ratios from λ = 2 up to λ = 15. Current density gradients are considered along the gas flow as well as in the transverse direction. The experimental results show that the current density gradient across the active area, although dependant on the reactants stoichiometry ratios, is relatively small as compared with a wide range of investigated stoichiometry ratios.

Effects of pulsed inhaled nitric oxide delivery on the distribution of pulmonary perfusion in spontaneously breathing and mechanically ventilated anesthetized ponies

OBJECTIVE To measure changes in pulmonary perfusion during pulsed inhaled nitric oxide (PiNO) delivery in anesthetized, spontaneously breathing and mechanically ventilated ponies positioned in dorsal recumbency. ANIMALS 6 adult ponies. PROCEDURES Ponies were anesthetized, positioned in dorsal recumbency in a CT gantry, and allowed to breathe spontaneously. Pulmonary artery, right atrial, and facial artery catheters were placed. Analysis time points were baseline, after 30 minutes of PiNO, and 30 minutes after discontinuation of PiNO. At each time point, iodinated contrast medium was injected, and CT angiography was used to measure pulmonary perfusion. Thermodilution was used to measure cardiac output, and arterial and mixed venous blood samples were collected simultaneously and analyzed. Analyses were repeated while ponies were mechanically ventilated. RESULTS During PiNO delivery, perfusion to aerated lung regions increased, perfusion to atelectatic lung regions decreased, arterial partial pressure of oxygen increased, and venous admixture and the alveolar-arterial difference in partial pressure of oxygen decreased. Changes in regional perfusion during PiNO delivery were more pronounced when ponies were spontaneously breathing than when they were mechanically ventilated. CLINICAL RELEVANCE In anesthetized, dorsally recumbent ponies, PiNO delivery resulted in redistribution of pulmonary perfusion from dependent, atelectatic lung regions to nondependent aerated lung regions, leading to improvements in oxygenation. PiNO may offer a treatment option for impaired oxygenation induced by recumbency.

Positronium as a biomarker of hypoxia

In this review article, we present arguments demonstrating that the advent of high sensitivity total-body PET systems and the invention of the method of positronium imaging, open realistic perspectives for the application of positronium as a biomarker for in-vivo assessment of the degree of hypoxia. Hypoxia is a state or condition, in which the availability of oxygen is not sufficient to support physiological processes in tissue and organs. Positronium is a metastable atom formed from electron and positron which is copiously produced in the intramolecular spaces in the living organisms undergoing positron emission tomography (PET). Properties of positronium, such as e.g., lifetime, depend on the size of intramolecular spaces and the concentration in them of oxygen molecules. Therefore, information on the partial pressure of oxygen (pO2) in the tissue may be derived from the positronium lifetime measurement. The partial pressure of oxygen differs between healthy and cancer tissues in the range from 10 to 50 mmHg. Such differences of pO2 result in the change of ortho-positronium lifetime e.g., in water by about 2–7 ps. Thus, the application of positronium as a biomarker of hypoxia requires the determination of the mean positronium lifetime with the resolution in the order of 2 ps. We argue that such resolution is in principle achievable for organ-wise positronium imaging with the total-body PET systems.

Late surfactant replacement therapy and its efficacy on severe bronchopulmonary dysplasia in National Children Hospital

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that is most commonly seen in premature infants who require prolonged mechanical ventilation and oxygen therapy. 75% of intubated infants have episodes of dysfunctional surfactants associated with lower levels of surfactant proteins. This study aims to evaluate the effectiveness of late surfactant therapy in treating BPD in premature infants. Nineteen preterm infants diagnosed with severe BPD requiring mechanic ventilation, according to Jobe and Bancalari, were treated with surfactant (Poractant alpha 100mg/kg intra-tracheal). Patients were observed for change in oxygen requirement before and at 1-h, 6-h, 12-h, 24-h, and 48-h after treatment. There were 13 boys and 6 girls; boy to girl ratio was 2.16/1. The mean gestation age was 28.3 ± 2 weeks; the mean birth weight was 1134.7 ± 314 gram. There was an increase in SpO2 (saturation of peripheral oxygen), PaO2 (the partial pressure of oxygen in arterial blood) and reduction in FiO2 (fraction of inspired oxygen), PaCO2 (the partial pressure of carbon dioxide in arterial blood), OI (oxygen index), MAP (mean airway pressure) and AaDO2 (Alveolar-to-arterial oxygen gradient) after surfactant (p < 0.05). Conclusion: In patients with severe BPD, late surfactant therapy has shown initial benefits in lung functions and reducing oxygen requirement.

Defect engineering of BCZT-based piezoelectric ceramics with high piezoelectric properties

The intrinsic conduction mechanism and optimal sintering atmosphere of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) ceramics were regulated by Mn-doping element in this work. By Hall and impedance analysis, the undoped BCZT ceramics exhibit a typical n-type conduction mechanism, and the electron concentration decreases with the increasing oxygen partial pressure. Therefore, the undoped ceramics exhibit best electrical properties (piezoelectrical constant d33 = 585 pC·N−1, electro-mechanical coupling factor kp = 56%) in O2. A handful of Mn-doping element would transfer the conduction mechanism from n-type into p-type. And the hole concentration reduces with the decreasing oxygen partial pressure for Mn-doped BCZT ceramics. Therefore, the Mn-doped ceramics sintered in N2 have the highest insulation resistance and best piezoelectric properties (d33 = 505 pC·N−1, kp = 50%). The experimental results demonstrate that the Mn-doping element can effectively adjust the intrinsic conduction mechanism and then predict the optimal atmosphere.