Ratio Of Oxygen Partial Pressure Research Articles

Different ventilation modes combined with ambroxol in the treatment of respiratory distress syndrome in premature infants.

The aim of the present study was to compare the effectiveness of different modes of mechanical ventilation in combination with secretolytic therapy with ambroxol in premature infants with respiratory distress syndrome. Seventy-three premature infants with hyaline membrane disease (HMD) (stage III–IV), also known as respiratory distress syndrome, who were supported by mechanical ventilation in the neonatal intensive care unit (NICU) of Xuzhou Central Hospital, were involved in the present study, between January 2013 and February 2015. Forty cases were randomly selected and treated with high frequency oscillatory ventilation (HFOV), forming the HFOV group, whereas 33 cases were selected and treated with conventional mechanical ventilation (CMV), forming the CMV group. Patients in the two groups were administered ambroxol intravenously at a dosage rate of 30 mg/kg body weight at the beginning of the study. The present study involved monitoring the blood gas index as well as changes in the respiratory function index in the two groups. Additionally, the incidence of complications in the premature infants in the two groups was observed prior to and following the ventilation. Pulmonary arterial oxygen tension (PaO2), the PaO2/fraction of inspired oxygen (FiO2) ratio, the oxygenation index [OI = 100 × mean airway pressure (MAP) × FiO2/PaO2], as well as the arterial/alveolar oxygen partial pressure ratio (a/APO2) = PaO2/(713 × FiO2 partial pressure of carbon dioxide (PaCO2)/0.8) of the patients in the HFOV group after 1, 12 and 24 h of treatment were significantly improved as compared to the patients of the CMV group. However, there was no significant difference between patients in the two groups with regard to the number of mortalities, complications such as pneumothorax, bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and the time of ventilation. In conclusion, combining HFOV with ambroxol secretolytic therapy is a more viable option, as the combined treatment resulted in significant improvements in arterial blood gas levels, oxygenation and the respiratory function of lungs in preterm infants.

A prospective randomized trial of tapered-cuff endotracheal tubes with intermittent subglottic suctioning in preventing ventilator-associated pneumonia in critically ill patients

BackgroundEndotracheal tube placement is necessary for the control of the airway in patients who are mechanically ventilated. However, prolonged duration of endotracheal tube placement contributes to the development of ventilator-associated pneumonias (VAPs). The aim of this study was to evaluate whether subglottic suctioning using TaperGuard EVAC tubes was effective in decreasing the frequency of VAP. MethodsA total of 276 mechanically ventilated patients for more than 72 hours were randomly assigned to group E (EVAC tube) and group C (conventional tube). All patients received routine care including VAP prevention measures during their intensive care unit stay. In group E, subglottic suctioning was performed every 6 hours. Outcome variables included incidence VAP, intensive care unit length of stay, and mortality. ResultsFrequency of intraluminal suction, mechanical ventilation–free days, reintubation, the ratio of arterial oxygen partial pressure to fractional inspired oxygen and mortality rate were similar between the 2 groups (P > .05). The mean cuff pressure in group E was significantly less than that in group C (P < .001). Ventilator-associated pneumonia was significantly less in group E compared with group C (P = .015). ConclusionThe use of intermittent subglottic secretion suctioning was associated with a significant decrease in the incidence of the VAP in critically ill patients. However, larger multicenter trials are required to arrive at a concrete decision on routine usage of TaperGuard tubes in critical care settings.

Thermal Properties of Perovskite-Type Oxides La0.6Sr0.4Co1-XFexO3-δ (0 ≤ x ≤ 1.0)

Introduction Solid oxide fuel cells (SOFCs) are an electrochemical conversion system with high efficiency and low-emission of pollution. In order to develop a commercial SOFC system with high performance and long-term stability, it is important to understand temperature distribution in the cell and stack [1]. For this purpose, thermal properties of SOFC components should be evaluated particularly under SOFC operating conditions, e.g. at elevated temperatures and under various oxygen partial pressures. Although there exist several reports on the thermal properties of the SOFC components, most of the data were measured at room temperature or in some specific atmospheric condition. [2-3] Thus, we aimed to investigate thermal properties of SOFC components as functions of temperature and oxygen partial pressure. Perovskite-type oxides La0.6Sr0.4Co1-x Fe x O3-δ (LSCF) are selected for this work. They are known to exhibit oxygen nonstoichiometry changes depending on temperature and oxygen potential. [4-7] The variation in oxygen vacancy concentration is known to influence electrochemical properties and mechanical properties. However, little is known about the effect on the thermal properties although. There exist several reports on the thermal properties of the LSCF. In this study, thermal diffusivities, heat capacities and thermal conductivities have been investigated by using the laser flash method and TG-DSC at high temperatures up to 1273 K under controlled oxygen atmospheres. Dependencies of the thermal properties of LSCF on temperature, oxygen partial pressure and the material composition will be discussed in terms of oxygen nonsotichiometry and crystal structures. Experimental Powders of La0.6Sr0.4Co1-x Fe x O3-δ (LSCF) were prepared by a conventional Pechini method. Obtained powders were hydrostatically pressed at 150 MPa into compacts, and then sintered in air at 1573K-1473K for 6h. For the thermal diffusivity measurement, the sintered compacts were cut into rectangles (c.a. 10 x 10 x 1 mm). For the TG-DSC measurement, the sintered compacts were cut smaller than Pt crucible. The phase of sintered samples was characterized by XRD to investigate any phase change after sintering. Thermal diffusivities and heat capacities of the LSCF were measured by using the laser flash method (LFA 457 Micro Flash, NETZSCH) and TG-DSC (STA 447, NETZSCH) in the oxygen partial pressure range from 10-4 to 0.2 bar and in the temperature range from R.T. to 1173 K. In order to control the atmospheres, a gas mixing system and an oxygen sensor are additionally attached to the laser flash system. The thermal conductivities (λ) of LSCF were calculated by using Eq(1). α : thermal diffusivity of LSCF with respect to temperature, ρ : the density of sintered LSCF sample and Cp: heat capacity of the LSCF as a function of temperature. λ = α·ρ·Cp (1) Results and Discussion In this study, the thermal properties of perovskite-type oxides La0.6Sr0.4Co1-x Fe x O3-δ (LSCF) were investigated. The thermal diffusivities of LSCF were dependence of temperature as well as oxygen partial pressure and Co contents ratio in intermediate temperatures (873K to 1173K).[Fig.1] The thermal diffusivity of LSCF decreased gradually as p(O2) decreased at all investigated temperatures, and decreased as temperature increased in all investigated p(O2) range. The thermal diffusivity depended on oxygen partial pressure more significant in lower oxygen partial pressure and at higher temperature. The thermal diffusivity increases with Co contents ratio increases and each composition increases with temperature through a maximum, then decreases. Heat capacity and thermal conductivity of LSCF (x=0, 0.8, 1.0) were almost constant from R.T to 873K, however increasing with increasing temperature over 873K. However, measured heat capacity compare with the Neumann-Kopp rule-specific heat of LSCF (x=0, 0.8, 1.0) were not consistent. LSCF is known to show the oxygen nonstoichiometry changes at relatively higher temperatures. Therefore, we suggest these dependenciese could be interpreted by the change in the oxygen nonstoichiometry, meaning that the thermal properties of LSCF were significantly affected by the oxygen nonstoichiometry.

Protective effects of thoracic epidural anesthesia on hypoxia-induced acute lung injury in rabbits.

The mechanism underlying the effect of thoracic epidural anesthesia (TEA) on hypoxia-induced acute lung injury (ALI) is currently unknown. In the present study, a rabbit acute lung injury model was established to investigate the effects of TEA on inflammatory factors, pulmonary surfactant and ultrastructure. A total of 56 rabbits were randomly assigned to four groups (n=14 per group): Control group (Group C), hypoxia group (Group H), sevoflurane group (Group S) and combined sevoflurane-epidural anesthesia group (Group ES). The ALI model was considered to have been successfully induced when the ratio of arterial oxygen partial pressure to fractional inspired oxygen was <300. The correct placement of a catheter for TEA was confirmed using epidurography. ALI was maintained for 3 h. Arterial blood samples were collected from all groups during spontaneous breathing (T0) and at 3 h after ALI induction (T5) in order to evaluate the serum levels of interleukin (IL)-6, IL-8 and IL-10. Bronchoalveolar lavage fluid was harvested to determine the total phospholipid, saturated phosphatidylcholine and total protein levels. Furthermore, the dry/wet weight ratio and the mRNA expression levels of IL-6, IL-8 and IL-10 in the lung tissue were determined using ELISA. In addition, light and transmission electron microscopy and histological techniques were used to examine the morphology of alveolar type II cells in the rat lung tissue. The results indicate that changes of serum IL-6, IL-8 and IL-10 levels following ALI were consistent with the changes in the mRNA expression levels of IL-6, IL-8 and IL-10 in the lung tissue. TEA attenuated these changes and thus reduced the severity of the ALI. In addition, TEA improved the alveolar structure, reduced the number of polymorphonuclear cells and mitigated the damage of lamellar bodies. In summary, the results of the present study indicate that TEA reduces lung tissue damage by inhibiting systemic and local inflammation, decreasing the inactivation of pulmonary surfactant and improving the alveolar ultrastructure following ALI.

Inflammatory response and pneumocyte apoptosis during lung ischemia-reperfusion injury in an experimental pulmonary thromboembolism model.

Lung ischemia–reperfusion injury (LIRI) may occur in the region of the affected lung after reperfusion therapy. The inflammatory response mechanisms related to LIRI in pulmonary thromboembolism (PTE), especially in chronic PTE, need to be studied further. In a PTE model, inflammatory response and apoptosis may occur during LIRI and nitric oxide (NO) inhalation may alleviate the inflammatory response and apoptosis of pneumocytes during LIRI. A PTE canine model was established through blood clot embolism to the right lower lobar pulmonary artery. Two weeks later, we performed embolectomy with reperfusion to examine the LIRI changes among different groups. In particular, the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2), serum concentrations of tumor necrosis factor-α (TNF-α), myeloperoxidase concentrations in lung homogenates, alveolar polymorphonuclear neutrophils (PMNs), lobar lung wet to dry ratio (W/D ratio), apoptotic pneumocytes, and lung sample ultrastructure were assessed. The PaO2/FiO2 in the NO inhalation group increased significantly when compared with the reperfusion group 4 and 6 h after reperfusion (368.83 ± 55.29 vs. 287.90 ± 54.84 mmHg, P < 0.05 and 380.63 ± 56.83 vs. 292.83 ± 6 0.34 mmHg, P < 0.05, respectively). In the NO inhalation group, TNF-α concentrations and alveolar PMN infiltration were significantly decreased as compared with those of the reperfusion group, 6 h after reperfusion (7.28 ± 1.49 vs. 8.90 ± 1.43 pg/mL, P < 0.05 and [(19 ± 6)/10 high power field (HPF) vs. (31 ± 11)/10 HPF, P < 0.05, respectively]. The amount of apoptotic pneumocytes in the lower lobar lung was negatively correlated with the arterial blood PaO2/FiO2, presented a positive correlation trend with the W/D ratio of the lower lobar lung, and a positive correlation with alveolar PMN in the reperfusion group and NO inhalation group. NO provided at 20 ppm for 6 h significantly alleviated LIRI in the PTE model. Our data indicate that, during LIRI, an obvious inflammatory response and apoptosis occur in our PTE model and NO inhalation may be useful in treating LIRI by alleviating the inflammatory response and pneumocyte apoptosis. This potential application warrants further investigation.

Effect of nasal continuous positive airway pressure and Bi-phase positive airway pressure on oxygen exchange indexes in newborns with mild to moderate neonatal respiratory distress syndrome

Objective To observe the effect of nasal continuous positive airway pressure (nCPAP) and Bi-phase positive airway pressure (BIPAP) on the oxygen exchange indexes in newborns with mild to moderate neonatal respiratory distress syndrome (NRDS). Methods After infusion of pulmonary surfactant into lung bilaterally, 116 cases with mild to moderate NRDS were treated with nCPAP(nCPAP group, n=75) and BIPAP(BIPAP group, n=41) respectively.Oxygen exchange indexes including arterial partial pressure of oxygen[pa(O2)], modified oxygenation index(P/F), alveolar- arterial oxygen tension difference(A-aDO2), respiratory index(RI), artery /alveolar oxygen partial pressure ratio[pa(O2)/pA(O2)] and pulmonary shunt fraction(Qs/Qt) were measured or calculated at 0 (before treatment), 2, 8 and 24 h after being treated with nCPAP or BIPAP. Results Six different oxygen exchange indexes of pa(O2), P/F, A-aDO2, RI, pa(O2)/pA(O2) and Qs/Qt in both groups didn't show statistical significance at 0 hour: pa(O2)(kPa)(6.1±0.6 vs 6.1±0.6, t=0.11, P>0.05), P/F(kPa)(15.59±1.45 vs 15.71±1.45, t=1.59, P>0.05), A-aDO2(kPa)(6.04±0.64 vs 6.24±0.69, t=1.59, P>0.05), RI(6.0±1.0 vs 6.2±1.1, t=1.35, P>0.05), pa(O2)/pA(O2) (0.24±0.02 vs 0.25±0.03, t=1.63, P>0.05)and Qs/Qt(%)(11.9±1.6 vs 11.6±1.6, t=1.10, P>0.05). A-aDO2, RI, pa(O2)/pA(O2) and Qs/Qt of BIPAP group had more improvement than those of nCPAP at 2 and 24 h, and oxygen exchange indexes at 2 h of BIPAP group and those of nCPAP group were: A-aDO2(kPa)(3.83±0.49 vs 4.24±0.67, t=18.26, P 0.05), P/F(28.49±3.17 vs 31.85±2.85, t=3.76.P>0.05)]. Nineteen cases in nCPAP group needed invasive mechanical ventilation, and only 3 cases in BIPAP group underwent the procedure; there was a significant difference (χ2=4.01, P<0.05). Oxygen exchange indexes in both groups were gradually improved from 2 h, 8 h to 24 h, but 22 deteriorated cases showed no improvement, who underwent invasive ventilation.Positive end-expiratory pressure(PEEP) positive airway pressure (EPAP) was (0.42±0.19) kPa in BIPAP group, and (0.56±0.23) kPa in nCPAP group(t=3.45, P<0.01). Conclusions 1.BIPAP and nCPAP can improve the ability of oxygen exchange in newborns with mild to moderate NRDS, but BIPAP is more effective than nCPAP, which can shorten the possibility of invasive ventilation and reduce the PEEP level.2.pa(O2), P/F, pa(O2)/pA(O2) and RI may be more suitable for evaluating oxygen exchange for neonatal NRDS. Key words: Neonatal respiratory distress syndrome; Noninvasive ventilation; Arterial partial pressure of oxygen; Oxygenation index; Alveolar arterial oxygen tension difference; Respiratory index; Arterial/alveolar oxygen partial pressure ratio; Pulmonary shunt fraction

Fabrication and properties of Al–P codoped p-type zinc oxide films by RF magnetron sputtering

Al–P codoped ZnO (ZnO:(Al, P)) films were grown on quartz substrate by radio frequency magnetron sputtering using mixture of argon and oxygen as sputtering gas. Types of conduction and electrical properties in ZnO:(Al, P) films were found to be dependent on oxygen partial pressure ratios in the sputtering gas mixture. When oxygen partial pressure ratio is 70 %, the codoped ZnO film had the best p-type conduction properties. It has room-temperature resistivity of 1.4 × 10−1 Ω cm, Hall mobility of 13.5 cm2/Vs and carrier concentration of 3.7 × 1018 cm−3. The p-type conduction behavior of the ZnO:(Al, P) film was confirmed by the rectifying I–V characteristics of the p-ZnO:(P, N)/n-ZnO homojunction. The phosphorus-related acceptor energy level was estimated to be located 126 meV above the valence band. Mechanism of the p-type conductivity was discussed in the present work.

Properties of Cu2O Thin Films for All-Oxide Solar Cells

In this work, p-type Cu2O thin films deposited by RF magnetron sputtering for Cu2O based all metal oxide solar cells were studied as a function of oxygen partial pressure ratio at room temperature. The Cu2O (111) x-ray diffraction peaks were indicated as a function of oxygen partial pressure ratio. Optical band gap energies of as-deposited Cu2O thin films ranged from 1.88 to 1.96 eV as a function of oxygen partial pressure ratio. The resistivity and mobility of the p-type Cu2O thin film with an oxygen partial pressure ratio of 2.4% was 2 ×104 Ω·cm and 15.1 cm2/V·s, respectively.

Early Use of Surfactant-BL after Lung Transplantation

Goal. To evaluate the clinical effect of early administration of surfactant-BL on pulmonary oxygenizing function and biomechanics in patients early after lung transplantation (LT). Materials and methods. Seven patients early after transplantation were administered with a surfactant-BL («Biosurf», St.-Petersburg, RF) to prevent or treat primary lung transplant disfunction. Results and conclusions. Multiple endobronchial administration of surfactant-BL (0, 24, and 48 hours) resulted in a progressive increase in the ratio of arterial oxygen partial pressure by an average of 94 mm Hg (p&lt;0.05) to oxygen fraction in a respiratory mixture ( РаО2^Ю2) at 48 hours after the surgery and by an average 1.2-fold increase in dynamic thoracopulmonary compliance accompanied by a reduction in the magnitude of PLGD. Employed protocol of surfactant-BL administration was favorable for optimizing the biomechanical properties and oxygenizing function of the lung. The findings clearly demonstrate that the early administration of surfactant-BL after LT should benefit the comprehensive prevention and treatment of PLGD that complicates the early postoperative period after LT.

Effects of the oxygen partial pressure during deposition on the material characteristics and magnetic properties of BaM thin films

Barium hexaferrite thin films were deposited on Si (100) substrates using a radio frequency magnetron sputtering system. The effects of oxygen partial pressure during deposition process on the material characteristics and magnetic properties of BaM thin films were investigated. X-ray diffraction data indicated that with the oxygen partial pressure ratio increasing from 0% to 8%, the diffraction peaks shift slightly towards the larger angles and the corresponding lattice parameters (a and c) decrease. The saturation magnetization (Ms) ranges from 200 to 358kA/m as the oxygen partial pressure ratio is varied from 0% to 8%. These changes are attributed to the different oxidation states of Fe ions in the films with oxygen excess or vacancies. When deposited with 1% oxygen partial pressure, the film possesses the highest saturation magnetization (358kA/m) and exhibits better perpendicular c-axis orientation in comparison with those deposited without oxygen partial pressure or with higher oxygen partial pressure.

Extravascular lung water indexed or not to predicted body weight is a predictor of mortality in septic shock patients

PurposeThe purpose was to investigate whether extravascular lung water (EVLW) indexed to actual body weight (EVLWa) is an independent predictor of mortality in patients with septic shock, to determine the relationship between EVLWa and other markers of lung injury, and to test if indexing EVLW with predicted body weight (EVLWp) strengthens its predictive power. MethodsExtravascular lung water, pulmonary vascular permeability index, and other markers of lung injury were measured prospectively in 55 patients with septic shock for 3 days. ResultsAt day 1, EVLWa, EVLWp, and pulmonary vascular permeability index were not significantly different between survivors and nonsurvivors. However, in parallel to the course of septic shock, these variables decreased only in the survivors and remained elevated in the nonsurvivors, reaching intergroup difference by day 3. In multiple logistic regression analysis, both EVLWa and EVLWp (at day 3) were predictors of mortality with an odds ratio of 2 (95% confidence interval, 1.12-3.7) and 1.7 (95% confidence interval, 1.1-2.5) per SD increase, respectively. The receiver operating characteristic curve analysis showed that EVLWp did not improve the discriminative power of EVLW to predict mortality. Extravascular lung water indexed to actual body weight correlated with lung injury score and with the ratio of arterial oxygen partial pressure to inspired oxygen fraction but not with static respiratory compliance. Indexing EVLW to predicted body weight did not ameliorate these correlations. ConclusionsExtravascular lung water indexed or not to predicted body weight is an independent predictor of mortality in patients with septic shock. Repeated measurements of EVLW indexes over time, rather than a too-early measurement, seem to be more appropriate for predicting outcome.

Characteristics of Tin Oxide-Based Thin Film Transistors Prepared by DC Magnetron Sputtering

Here we demonstrate the fabrication of SnO(x) thin-film transistors (TFTs), where SnO(x) thin films are deposited as an active channel layer by DC magnetron sputtering. We analyzed the effects of the oxygen partial pressure ratio and post-deposition heat treatment (PDHT) on the characteristics of the SnO(x) thin films. We found improved performance of the TFTs obtained by using interface modification with the optimized deposition condition of SnO(x) thin films. These results are helpful for fabricating oxide-TFTs, including simple binary oxide semiconductors, as an active channel layer.

SPUTTERED TiO2 FILMS FOR PHOTOVOLTAIC CELL'S ANTIREFLECTION COATING

TiO2 films were prepared by the magnetron sputter system with various oxygen partial pressure ratios, for the application of photovoltaic (PV) cells, TiO2 single-layer and SiO2/TiO2 double-layer antireflection (AR) coatings were deposited on Si substrate. The experimental results indicate that TiO2 film deposited at oxygen partial pressure ratio of 15.4% exhibits smooth surface morphology, amorphous structure, and good optical transmittance, which is suitable for AR coating in the PV cell structure system. Furthermore, the weighted average reflectance in the range of 400–900 nm was about 10.3% and 3.7% for the TiO2 single-layer and SiO2/TiO2 double-layer AR coatings, respectively. With a double-layer AR coating, a 50.8% improvement in the efficiency of a Si PV cell was achieved.

Influence of the hot oxygen corona on the satellite drag in the Earth’s upper atmosphere

Calculation results on the possible influence of the hot oxygen fraction on the satellite drag in the Earth’s upper atmosphere on the basis of the previously developed theoretical model of the hot oxygen geocorona are presented. Calculations have shown that for satellites with orbits above 500 km, the contribution from the corona is extremely important. Even for the energy flux Q 0 = 1 erg cm−2 s−1, the contribution of the hot oxygen can reach tens of percent; and considering that real energy fluxes are usually higher, one can suggest that for extreme solar events, the contribution of hot oxygen to the atmospheric drag of the satellite will be dominant. For lower altitudes, the contribution of hot oxygen is, to a considerable degree, defined by the solar activity level. The calculations imply that for the daytime polar atmosphere, the change of the solar activity level from F 10.7 ∼ 200 to F 10.7 ∼ 70 leads to an increase in the ratio of the hot oxygen partial pressure to the thermal oxygen partial pressure by a factor of almost 30, from 0.85 to 25%. The transition from daytime conditions to nighttime conditions almost does not change the contribution from suprathermal particles. The decrease of the characteristic energy of precipitating particles, i.e., for the case of charged particles with a softer energy spectrum, leads to a noticeable increase of the contribution of the suprathermal fraction, by a factor of 1.5–2. It has been ascertained that electrons make the main contribution to the formation of the suprathermal fraction; and with the increase of the energy of precipitating electrons, the contribution of hot oxygen to the satellite drag also increases proportionally. Thus, for a typical burst, the contribution of the suprathermal fraction is 30% even at relatively high solar activity F 10.7 = 135.

Prone position and recruitment manoeuvre: the combined effect improves oxygenation

IntroductionAmong the various methods for improving oxygenation while decreasing the risk of ventilation-induced lung injury in patients with acute respiratory distress syndrome (ARDS), a ventilation strategy combining prone position (PP) and recruitment manoeuvres (RMs) can be practiced. We studied the effects on oxygenation of both RM and PP applied in early ARDS patients.MethodsWe conducted a prospective study. Sixteen consecutive patients with early ARDS fulfilling our criteria (ratio of arterial oxygen partial pressure to fraction of inspired oxygen (PaO2/FiO2) 98.3 ± 28 mmHg; positive end expiratory pressure, 10.7 ± 2.8 cmH2O) were analysed. Each patient was ventilated in both the supine position (SP) and the PP (six hours in each position). A 45 cmH2O extended sigh in pressure control mode was performed at the beginning of SP (RM1), one hour after turning to the PP (RM2) and at the end of the six-hour PP period (RM3).ResultsThe mean arterial oxygen partial pressure (PaO2) changes after RM1, RM2 and RM3 were 9.6%, 15% and 19%, respectively. The PaO2 improvement after a single RM was significant after RM3 only (P < 0.05). Improvements in PaO2 level and PaO2/FiO2 ratio were transient in SP but durable during PP. PaO2/FiO2 ratio peaked at 218 mmHg after RM3. PaO2/FiO2 changes were significant only after RM3 and in the pulmonary ARDS group (P = 0.008). This global strategy had a benefit with regard to oxygenation: PaO2/FiO2 ratio increased from 98.3 mmHg to 165.6 mmHg 13 hours later at the end of the study (P < 0.05). Plateau airway pressures decreased after each RM and over the entire PP period and significantly after RM3 (P = 0.02). Some reversible side effects such as significant blood arterial pressure variations were found when extended sighs were performed.ConclusionsIn our study, interventions such as a 45 cmH2O extended sigh during PP resulted in marked oxygenation improvement. Combined RM and PP led to the highest increase in PaO2/FiO2 ratio without major clinical side effects.

Effects of oxygen partial pressure on resistive switching characteristics of ZnO thin films by DC reactive magnetron sputtering

Cu/ZnO/n +-Si structures were prepared by magnetron sputtering of a layer of ZnO thin film onto heavily doped silicon substrate, followed by thermal evaporation of a thin layer of metallic Cu. The resistive switching characteristics of Cu/ZnO/n +-Si structures were investigated as a function of oxygen partial pressure during ZnO deposition. Reproducible resistive switching characteristics were observed in ZnO thin films deposited at 20%, 33% and 50% oxygen partial pressure ratios while ZnO thin film deposited at 10% oxygen partial pressure ratio did not show resistive switching behavior. The conduction mechanisms in high and low resistance states are dominated by space-charge-limited conduction and ohmic behavior respectively, which suggests that resistive switching behaviors in such structures are related to filament formation and rupture. It is also found that the reset current decreases as oxygen partial pressure increases, due to the variation of oxygen vacancy concentration in the ZnO thin films.

Room-temperature growth and optoelectronic properties of GZO/ZnO bilayer films on polycarbonate substrates by magnetron sputtering

Gallium-doped zinc oxide (GZO) films have been grown on polycarbonate (PC) substrates with and without ZnO buffer layers by radio frequency (r.f.) magnetron sputtering at room temperature. The optimization of growth parameters (sputtering power, sputtering pressure, sputtering time, oxygen partial pressure ratio) on ZnO buffer layers with multiple qualities based on the orthogonal array has been studied. The optimal parameter of the ZnO buffer layer could be obtained according to the range analysis method. The lowest electrical resistivity of GZO/ZnO/PC films is about 5.21×10 -4 Ωcm, and the transmittance in the visible range is about 80%, using air as reference. The good transparency-conducting property and the room-temperature depositon on polymeric substrates enable GZO films to be widely used in flexible optoelectronic devices such as thin film solar cells.

Deposition and properties of B–N codoped p-type ZnO thin films by RF magnetron sputtering

B–N codoped p-type ZnO thin films have been realized by radio frequency (rf) magnetron sputtering using a mixture of argon and oxygen as sputtering gas. Types of conduction and electrical properties in codoped ZnO films were found to be dependent on oxygen partial pressure ratios in the sputtering gas mixture. When oxygen partial pressure ratio was 70%, the codoped ZnO film showed p-type conduction and had the best electrical properties. Additionally, the p-ZnO/ n-Si heterojunction showed a clear p– n diode characteristic. XRD results indicate that the B–N codoped ZnO film prepared in 70% oxygen partial pressure ratio has high crystal quality with (0 0 2) preferential orientation. Meanwhile, the B–N codoped ZnO film has high optical quality and displays the stronger near band edge (NBE) emission in the temperature-dependent photoluminescence spectrum, the acceptor energy level was estimated to be located at 125 meV above the valence band.

RF Magnetron Sputtering법으로 제작된 (Pb0.92La0.08)(Zr0.65Ti0.35)O3박막의 Ar/O2분압비에 따른 강유전 특성연구

rf magnetron sputtering 법을 이용하여 Pt/Ti/<TEX>$SiO_2$</TEX>/Si 기판 위에 buffer layer인 <TEX>$TiO_2$</TEX> 층을 증착한 후 PLZT 강유전체 박막을 증착하였다. PLZT 박막 증착 시 가스 분압비가 박막의 특성에 미치는 영향을 알아보기 위해 Ar/<TEX>$O_2$</TEX> 분압비를 각각 27/1.5 sccm, 23/5.5 sccm, 21/7.5 sccm, 19/9.5 sccm로 변화시키면서 박막을 증착하였다. 이들 박막의 구조적인 특성을 분석하기 위해 X-선 회절법을 사용하였으며 FE-SEM을 이용하여 입자상을 관찰하였다. 또한 박막의 유전특성을 분석하기 위해 Precision LC를 이용하여 이력곡선, 잔류분극, 누설전류를 측정하였다. 산소 분압이 높아질수록 박막의 결정성 및 치밀성이 저하되었으며, (110) 방향에서 (111) 방향으로 우선배향성이 변화하는 것을 확인하였다. 산소 분압비의 변화는 박막 표면 및 강유전 특성에 영향을 미치는 것으로 판단된다. PLZT ferroelectric thin films were deposited on Pt/Ti/<TEX>$SiO_2$</TEX>/Si substrate with <TEX>$TiO_2$</TEX> buffer layer in between by rf magnetron sputtering method. In order to investigate the effect of Ar/<TEX>$O_2$</TEX> partial pressure ratio on the ferroelectric properties of PLZT thin films, PLZT thin films were deposited at various Ar/<TEX>$O_2$</TEX> partial pressure ratio ; 27/1.5 seem, 23/5.5 seem, 21/7.5 seem and 19/9.5 seem. The crystallinities of PLZT thin films were analyzed by XRD. The surface morphology was observed using FE-SEM. The P-E hysteresis loops, the remanent polarization characteristics and the leakage current characteristics were obtained using a Precision LC. The crystallinity and elaborateness of PLZT thin films were decreased as increasing the oxygen partial pressure ratio. And preferred orientation of PLZT thin films changed from (110) plane to (111) plane. The oxygen partial pressure ratio affects the thin film surface morphology and the ferroelectric properties.

Oxygen-doped Si15Sb85 thin film for good data retention and high speed phase-change memory application

Te-free SixSb100−x (x = 5, 15, 25, 42) thin films are proposed for electronic phase-change memory application and the oxygen doping effect on Si15Sb85 film is investigated in detail. Improved electrical properties are obtained when the oxygen partial pressure ratio is 10%. The crystalline resistivity of Si15Sb85 film is enhanced and the amorphous/crystalline resistivity ratio is also increased to more than 104. The crystallization temperature of the oxygen-doped Si15Sb85 film is 229 °C and maximum temperature for a 10 year lifetime is estimated to be 129 °C with crystallization activation energy of 3.11 eV, which promises better data retention than conventional Ge2Sb2Te5 film. X-ray diffraction patterns indicate that both pure and oxygen-doped Si15Sb85 films crystallize into a hexagonal phase similar to Sb. A phase-change memory device using oxygen-doped Si15Sb85 film can be successfully switched with a 100 ns-1.4 V SET pulse and a 20 ns-7 V RESET pulse. And a SET process as fast as 40 ns is achieved along with a RESET/SET resistance ratio of about 35.