Oxidation of Fe-Cr-Ni Alloys in a Low Oxygen Partial Pressure Atmosphere to Mitigate Coke Formation

Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed by energydispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-cokingperformance of a mini tube made of a HP40 (25Cr35Ni) alloy was evaluated on a bench scale pyrolysis and coking test unit.The results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partialpressure atmosphere. The oxide films were mainly composed of MnCr_(2)O_(4) and Cr_(2)O_(3). The average mass of coke in the minitube with oxide film decreased by 87% relative to that of a tube without an oxide film when the cracking temperature was 900℃. The ethylene, propylene, and butadiene yields in the pyrolysis tests were almost the same for the mini tubes withand without an oxide film. The oxide film on the alloy surface effectively inhibited catalytic filamentous coke formation.An industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantlyextended.

The Effect of Oxygen Partial Pressure during Active Layer Deposition on Bias Stability of a-InGaZnO TFTs

The effect of oxygen partial pressure （Po2） during the channel layer deposition on bias stability of amorphous indium-gallium-zinc oxide （a-IGZO） thin film transistors （TFTs） is investigated. As Po2 increases from 10% to 30%, it is found that the device shows enhanced bias stress stability with significantly reduced threshold voltage drift under positive gate bias stress. Based on the x-ray photoelectron spectroscopy measurement, the concentration of oxygen vacancies （Or） within the a-IGZO layer is suppressed by increasing Po2. Meanwhile, the low-frequency noise analysis indicates that the average trap density near the channel/dielectric interface continuously drops with increasing Po2. Therefore, the improved interface quality with increasing Po2 during the channel layer deposition can be attributed to the reduction of interface Ov-related defects, which agrees with the enhanced bias stress stability of the a-IGZO TFTs.

Effect of Oxygen Partial Pressure on Epitaxial Growth and Properties of Laser-Ablated AZO Thin Films

Al-doped ZnO（AZO） thin films were grown on c-sapphire substrates by laser ablation under different oxygen partial pressures（P_（O2））.The effect of P_（O2） on the crystal structure,preferred orientation as well as the electrical and optical properties of the films was investigated.The structure characterizations indicated that the as-grown films were single-phased with a wurtzite ZnO structure,showing a significant c-axis orientation.The films were well crystallized and exhibited better crystallinity and denser texture when deposited at higher P_（O2）.At the optimum oxygen partial pressures of 10- 15 Pa,the AZO thin films were epitaxially grown on c-sapphire substrates with the（0001） plane parallel to the substrate surface,i e,the epitaxial relationship was AZO（000 1） // A1_2O_3（000 1）.With increasing P_（O2）,the value of Hall carrier mobility was increased remarkably while that of carrier concentration was decreased slightly,which led to an enhancement in electrical conductivity of the AZO thin films.All the films were highly transparent with an optical transmittance higher than 85%.

Self-healing behavior of Ti_(2)AlC at a low oxygen partial pressure

Ti_(2)AlC,a MAX phase ceramic,has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon healing at high temperatures in air(high oxygen partial pressures).However,such healing ability to repair damages in vacuum or low oxygen partial pressure conditions remains unknown.Here,we report on the self-healing behavior of Ti_(2)AlC at a low oxygen partial pressure of about 1 Pa.The experimental results showed that the strength recovery depends on both healing temperature and time.After healing at 1400℃for 1–4 h,the healed samples exhibited the recovered strengths even exceeding the original strength of 375 MPa.The maximum recovered strength of~422 MPa was achieved in the healed Ti_(2)AlC sample after healing at 1400 for 4 h,about 13%higher than the original strength.Damages were healed by the formed℃TiCx from the decomposition of Ti_(2)AlC.The decomposition-induced crack healing as a new mechanism in the low oxygen partial pressure condition was disclosed for the MAX ceramics.The present study illustrates that key components made of Ti_(2)AlC can prolong their service life and keep their reliability during use at high temperatures in low oxygen partial pressures.

Analysis of metabolic alterations in Arabidopsis following changes in the carbon dioxide and oxygen partial pressures

As sessile organisms,plants are subject to a multitude of environmental variations including several which directly affect their interaction with the atmosphere.Given the indiscriminant nature of Rubisco,the relative rates of photosynthesis and photorespiration are known to be responsive to changes in gas composition.However,comprehensive profiling methods have not yet been applied in order to characterize the wider consequences of these changes on primary metabolism in general.Moreover,although transcriptional profiling has revealed that a subset of photorespiratory enzymes are co-expressed,whether transcriptional responses play a role in short-term responses to atmospheric compositional changes remains unknown.To address these questions,plants Arabidopsis thaliana（Arabidopsis） ecotype Columbia（Col-O） grown under normal air conditions were transferred to different CO_2 and O_2 concentrations and characterized at the physiological,molecular,and metabolic levels following this transition.The results reveal alterations in the components,which are directly involved in,or supporting,photorespiration,including transcripts and metabolite levels.The results further highlight that the majority of the regulation of these pathways is not mediated at the level of transcription and that the photorespiratory pathway is essential also in conditions in which flux through the pathway is minimized,yet suggest that flux through this pathway is not mediated at the level of transcription.

Effect of cerium addition on oxidation behavior of 25Cr20Ni alloy under low oxygen partial pressure

The influence of Ce addition on the oxidation behavior of 25Cr20Ni alloy at 950 oC under low oxygen partial pressure was inves-tigated. The oxidized samples were characterized by using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS）, and scratch tester to obtain the oxide phases, morphology, thickness, composition and adhesion property of the oxide scales. The experiment results indicated that a small amount of Ce addition （0.02 wt.% or 0.05 wt.%） promoted oxidation resistance and inhibited the growth of the needlelike oxide. The Ce addition also decreased the formation of MnCr2O4 but promoted the SiO2 formation un-derneath the Cr2O3, which largely contributed to the improvement of oxide scale spallation resistance. For the sample with 0.3 wt.% Ce addi-tion, the oxidation rate significantly increased and the spallation resistance of the oxide scale decreased.

Effect of Oxygen Partial Pressure on Phase Equilibria and Liquidus in CaO-Al_2O_3-FeO_x System

A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pres- sure on the phase equilibria and liquidus in CaO-Al2O3- FeOx system with the intermediate oxygen partial pressures of 10.13 Pa and 1.01 × 10^-3 Pa. The equilibrated phases and their compositions of the quenched samples were analyzed by using SEM/EPMA （Scanning Electron Microscope/Electron Probe Micro Analysis） and XRD （X Ray Diffraction）. The phase equilibrium results include two cases, the two phase coexistence and the three-phase coexistence in the high Al2O3 region with oxygen partial pressure of either 10.13 Pa or 1.01 × 10^-3 Pa. Effects of oxygen partial pressure and temperature on the liquidus along the primary phase fields of CaO · Al2O3 and CaO · 2Al2O3 were nota hle. With the decrease of oxygen partial pressure, the liquid area expands and the liquidus of CaO · Al2O3 and CaO · 2Al2O3 primary fields moves to the Al2O3-FeOx region. On the other hand, the liquid area of CaO Al2O3-FeOx sys tem extends extremely to the high Al2O3 region with the temperature increasing from 1 400 to 1 500℃, especially at lower oxygen partial pressure. The present experiment results are in good agreement with the calculated ones by FactSage.

Effect of Ca^(2+) complexation on oxygen partial pressure in the urinary bladder meridian of goats

The aim of this paper was to explore the relationship between energy metabolism and the meridian phenomenon.The manner of change of oxygen partial pressure in acupoints and no-acupoints of the urinary bladder meridian of goats was observed with a needle-type tissue oxygen tension sensor after the acupuncture effect was blocked by Ca^(2+) complexation with ethylenediamine tetraacetic acid(EDTA)-Na2.The results showed that:(1)the concentration of calcium ion in urinary bladder meridian acupoints was higher than that in no-acupoints(P<0.01 or P<0.05);(2)the tissue oxygen tension in urinary bladder meridian acupoints was higher than that in no-acupoints(P<0.01);(3)the oxygen partial pressure in acupoints decreased significantly after injection with EDTA-Na2,compared with injection of either normal sodium or nothing(P<0.01);(4)the oxygen partial pressure in acupoints was higher than that in no-acupoints after EDTA-Na2 injection(P<0.01).Acupuncture could reduce oxygen partial pressure in acupoints by regulating microcirculation and increasing metabolic levels.

Efficacy of Huangma Ding or autologous platelet-rich gel for the diabetic lower extremity arterial disease patients with foot ulcers

BACKGROUND Diabetes foot is one of the most serious complications of diabetes and an important cause of death and disability,traditional treatment has poor efficacy and there is an urgent need to develop a practical treatment method.AIM To investigate whether Huangma Ding or autologous platelet-rich gel(APG)treatment would benefit diabetic lower extremity arterial disease(LEAD)patients with foot ulcers.METHODS A total of 155 diabetic LEAD patients with foot ulcers were enrolled and divided into three groups:Group A(62 patients;basal treatment),Group B(38 patients;basal treatment and APG),and Group C(55 patients;basal treatment and Huangma Ding).All patients underwent routine follow-up visits for six months.After follow-up,we calculated the changes in all variables from baseline and determined the differences between groups and the relationships between parameters.RESULTS The infection status of the three groups before treatment was the same.Procalcitonin(PCT)improved after APG and Huangma Ding treatment more than after traditional treatment and was significantly greater in Group C than in Group B.Logistic regression analysis revealed that PCT was positively correlated with total amputation,primary amputation,and minor amputation rates.The ankle-brachial pressure and the transcutaneous oxygen pressure in Groups B and C were greater than those in Group A.The major amputation rate,minor amputation rate,and total amputation times in Groups B and C were lower than those in Group A.CONCLUSION Our research indicated that diabetic foot ulcers(DFUs)lead to major amputation,minor amputation,and total amputation through local infection and poor microcirculation and macrocirculation.Huangma Ding and APG were effective attreating DFUs.The clinical efficacy of Huangma Ding was better than that of autologous platelet gel,which may be related to the better control of local infection by Huangma Ding.This finding suggested that in patients with DFUs combined with coinfection,controlling infection is as important as improving circulation.

Influence of moderate hypothermia on cerebral oxygenation in pigs with intracranial hypertension

BACKGROUND： Moderate hypothermia is one of the effective therapeutic methods for head injury in recent years, there are many mechanisms of moderate hypothermia for brain protection, and its influence on cerebral oxygenation is also one of them. OBJECTIVE： To observe the influence of moderate hypothermia on cerebral oxygenation of animals with acute intracranial hypertension, and further investigate the protective mechanism of moderate hypothermia. DESIGN： A randomized controlled trial. SETTING： Department of Neurosurgery, Renji Hospital affiliated to the Medical College of Shanghai Jiao Tong University. MATERIALS： Twenty healthy little pigs, either male or female, weighing 4.5-5.5 kg, were used. Neurotrend-typed multiparameter monitoring system （Diametrics Company, British）; CMA/100 micro-injection pump （Carnegie Company, Sweden）. METHODS： The experiment was conducted in the Changzheng Hospital affiliated to the Second Military Medical University of Chinese PLA in November, 2001. The pigs were randomized into two groups： the normothermia group （control group, n =10） and moderate hypothermia group （n =10）. ① Bilateral femoral arteries were separated, one was connected to pressometer for monitoring mean arterial pressure （MEP）, and the other for analysis of blood gases [including peripheral blood pH value, arterial partial pressure of carbon dioxide （PaCO2）, arterial partial pressure of carbon dioxide （PaCO2）, HCO3-]. ② Rectal temperature was monitored with mercurial thermometer. ③ Intracranial pressure was monitored using Camino optic ICP probe placed in the subdural space. ④ Neurotrend multiparameter monitoring sensor was inserted into the white matter for about 4 cm to determine cerebral perfusion pressure （CPP, CPP=MAP（ICP）, brain tissue partial oxygen pressure （PO2）, partial pressure of carbon dioxide （PCO2）, HCO3- and brain temperature. The rectal temperature of animals in the moderate hypothermia group was lowered to 34 ℃ using ice bags, and the body temperature was maintained at 33-35 ℃ for 2 hours. The changes of the parameters were observed continuously, and the pigs in the normothermia group were not treated with cooling. MAIN OUTCOME MEASURES： ① MAP, ICP, rectal temperature, CCP; Indexes of cerebral oxygenation detected with Neurotrend-typed multiparameter monitoring system; ② Results of blood gases analysis in the moderate hypothermia group. RESULTS： All the 20 pigs were involved in the analysis of results. ① MAP, ICP, rectal temperature, CCP and indexes of cerebral oxygenation： In the moderate hypothermia group, the ICP after cooling was obviously lower than that before cooling [（3.31±1.19）, （5.33±0.95） kPa, P 〈 0.05], CCP was higher, brain tissue PCO2 [（12.03±1.73）, （10.59±2.01） kPa, P 〈 0.05], and brain tissue pH value was higher [（7.03± 1.63）, （9.40±1.30） kPa, P 〈 0.05], whereas the brain temperature was decreased as compared with that before cooling [（34.9±0.3）, （37.2±0.2） ℃, P 〈 0.05]. ② Results of blood gases analysis in the moderate hypothermia group： There were no significant differences in the parameters of peripheral arterial blood gases analysis before and after cooling in the moderate hypothermia group （P 〉 0.05） CONCLUSION： Moderate hypothermia will not impair the cerebral oxygenation, and it can reduce brain tissue CO2 and decrease brain tissue acidosis.

Study on Oxygen Supply and Protection of Bone Marrow in Acute Radiation injured Mice

After irradiated by & Gy 60Co γ-ray, mice were intraperitoneally injected immediately with 0.2 ml 100 % compound blood-activating soup twice a day for 10 days. The in situ ulnar bone marrow partial pressure of oxygen (PbO2) was determined in vivo before, during and after irradiation respectively. The bone marrow sections in the same part were observed. Our results showed that the normal murine ulnar PbO2 was 12.72±1. 05kpa. During irradiation, the level of PbO2 decreased to 10. 78±1. 17 kpa (P＜0. 001). And 3 days after irradiation, PbO2 decreased to 9. 75±0. 52 kpa, suggesting that the commonly used 'blood-activating and stasis-eliminating' Chinese drugs could promote the rehabilitation and proliferation of bone marrow microvessels in the acute radiation injured mice, expand their areas, increase the oxygen supply of bone marrow microenviroment, thereby leading to PbO2 much higher increase than that of control group. It is also helpful in the proliferation and rehabilitation of hematopoietic cells.

Growth Mechanism and Characterization of ZnO 3D Nanocrystals by Laser Irradiation & Coaxially Transporting O_2

Different three-dimension （3D） nanotetrapods, containing club-like nanocrystals, nanotetrapods and four-foot-like nanocrystals were synthesized from Zinc sheet via CO2 laser irradiation and coaxially transporting O2. Different nanoproducts were fabricated by changing the content of oxygen in the experiment. The morphologies, components, phase structures and optical properties of the products were investigated by a field-emission scanning electron microscopy, an X-ray diffraction, an energy dispersed X-ray spectrometer and a photoluminescence spectroscope. The X-ray diffraction spectra were obtained on a Rigaku D/max 2500PC diffractometer. The experimental results reveal that high quality ZnO nanotetrapods can be fabricated on the special parameters, and growth of ZnO nanotetrapods depends on Vapour-Liquid-Solid（VLS） model, and the content of oxygen in the gas, namely, oxygen partial pressure is one of main factors to control morphologies and optical properties ofZnO nanotetrapods; these advantages above are important for realization of optoelectronic devices.

Thermodynamics of some ZrO_2-containing ceramics

Thermodynamic assessment in the ternary systems ZrO2 -CeO2 -Y2 O3, ZrO2 -CeO2 -Ce2 03 and the limiting binaries ZrO2 -Y2 O3, ZrO2 -CeO2, CeO2 -Y2 03, ZrO2 -Ce2O3, CeO2 -Ce2O3 as well as the modeling for oxides are reviewed comprehensively. Based on the recent estimations on the YO1.5-CeO2, ZrO2-CeO2 and ZrO2 -YO1.6 systems, isothermal sections at 1273 and 1 973 K of the ternary CeO2- ZrO2-YO1.5system are calculated. In the system of ZrO2-CeO2-Ce2O3, the complex relation between the nonstoichiometry （y） in CeO2-x, the composition of the ZrO2 -CeO2 solid solution and the oxygen partial pressure （Po2 ） for different ZrO2 containing solid solutions CexZr1-xO2-x. are evaluated from 1 473 to 1 773 K. The relation between the degree of Ce^＋4 reduction to Ce.3 under different Po2 in the fluorite CeO2-xy and CexZr1-xOz-x solid solutions at different temperatures can be used as a guide in the development of functional ceramics.

Preparation and Preservation of Hypoxia UW Solution

In order to explore the method to prepare hypoxia UW solution and the stability and preservation of hypoxia UW solution, UW solution was purged by argon or air for 15 min or 60 at a flow rate of 0.8 or 2 L/min, and the oxygen partial pressure of UW solution was detected. The hypoxia UW solution was exposed to the air or sealed up to preserve by using different methods, and the changes of oxygen partial pressure was tested. The results showed that oxygen partial pressure of 50 mL UW solution, purged by argon for 15 min at a flow rate of 2 L/min, was declined from 242±6 mmHg to 83±10 mmHg. After exposure to the air, oxygen partial pressure of hypoxia UW solution was gradually increased to 160±7 mmHg at 48 h. After sealed up by the centrifuge tube and plastic bad filled with argon, oxygen partial pressure of hypoxia UW solution was stable, about 88±13 mmHg at 72 h. It was concluded that oxygen of UW solution could be purged by argon efficiently. Sealed up by the centrifuge tube and plastic bag filled with argon, oxygen partial pressure of UW solution could be stabilized.

Experimental Study on the Cryopreservation of LLC-PK1 Epithelial Cells with Hypoxic UW Solution

The effects of oxygen partial pressure on cryopreservation of the cells with organ preservation solution were explored. Hypoxic UW solution was made by purging the UW solution with argon. The pig proximal tubule epithelial cells （LLC-PK1 cells） were cryopreserved in hypoxic UW solution （Ar-UW group） or standard UW solution （UW group） at 4℃ for 48 h. Trypan blue staining and LDH detection were performed to evaluate the injury of the cells. The results showed that the oxygen partial pressure in Ar-UW group was significantly declined from 242±6 mmHg to 83±10 mmHg. After cryopreservation at 4℃ for 48 h, LDH leakage rate and Trypan blue-stained rate in Ar-UW group were （11.3±3.4）% and （10.5±4.7）%, respectively, which were significantly lower than in UW group [（49.5±6.9）% and （47.6±9.3）% respectively, both P〈0.01]. It was concluded that lower oxygen partial pressure of UW solution was more beneficial to the cryopreservation of LLC.

Relationship between PaO_(2)/FiO_(2) and delirium in intensive care:A cross-sectional study

Background::To investigate the relationship between partial pressure of oxygen(PaO_(2))/fraction of inspired oxygen(FiO_(2))and the probability of delirium in intensive care units(ICUs).Methods::The investigation was a cross-sectional study that involved the collection of data from patients admitted to the Xiang Ya Hospital Cardiothoracic Surgical Care Unit and Comprehensive Intensive Care Unit from 01 September 2016 to 10 December 2016.Delirium was diagnosed using the simplified version of the Chinese Confusion Assessment Method(CAM)for the ICU.Demographic and medical data were obtained within 24 h of each patient admitted in the ICU.The PaO_(2)/FiO_(2) of each patient was recorded 24 h after admission in the ICU.The patients were divided into three groups according to PaO_(2)/FiO_(2) data:normal(PaO_(2)/FiO_(2)≥300 mmHg),slightly low(200≥PaO_(2)/FiO_(2)<300 mmHg),and severely low(PaO_(2)/FiO_(2)<200 mmHg).Baseline characteristics were compared in the three groups.Results of the unadjusted model,minimally adjusted model,and fully adjusted model are presented.Results::A total of 403 participants were included in the study,of which 184(45.7%)developed delirium.Age(P<0.001),Sequential Organ Failure Assessment(SOFA)score(P<0.001),Acute Physiology and Chronic Health Evaluation(APACHE)II score(P<0.001),mechanical ventilation time(P<0.001),history of hypertension(P=0.040),heart disease(P=0.040),sedation(P=0.001),and PaO_(2)/FiO_(2)(P=0.006)were significantly associated with delirium in univariate analysis.Multivariate regression analysis models were used to further analyze the associations between PaO_(2)/FiO_(2) and delirium.In the crude model,for 1 standard deviation(SD)increase in PaO_(2)/FiO_(2),the odds ratio(OR)of delirium was 0.8(95%confidence interval[CI]:0.6-0.9),but there was no significant correlation in the fully adjusted model.There was a non-linear relationship between the PaO_(2)/FiO_(2) and delirium in a generalized additive model.A two-piecewise linear regression model was used to calculate a PaO_(2)/FiO_(2) threshold of 243 mmHg.On the left side of the threshold,the OR was 0.9 and the 95%CI was 0.9-1.0(P=0.013)when PaO_(2)/FiO_(2) increased by 1 SD.Conclusions::PaO_(2)/FiO_(2) was negatively associated with delirium when PaO_(2)/FiO_(2) was below the identified threshold.As a readily available laboratory indicator,PaO_(2)/FiO_(2) has potential value in the clinical evaluation of risk of delirium in ICU patients.

Effect of furnace atmosphere on sintering process of chromium-containing steel via powder metallurgy

During a powder metallurgy process such as sintering,the primary role played by the atmosphere in furnace is to prevent an excessive oxidation of powder compacts in case of the formation of oxides as residuals on powder surfaces.In particular,the adjustment of furnace atmosphere is the key to eliminate the phenomenon"decarburization"likely to occur in carbon-containing compacts.A continuous belt furnace was used to stabilize the potentials of carbon and oxygen in zones divided by sintering,delubrication,and cooling.Chromium and manganese,which are sensitive to oxygen,were added to improve mechanical properties in a cost-effective way.Powders of steel containing chromium were sintered in an atmosphere composed of CO,O_(2),and H_(2).The effects of atmosphere,lubricant,and graphite on oxidation(or reduction)and decarburization(or carburization)were investigated.Superior quality was achieved under the control of delubrication atmosphere.It is indicated that in a protective atmosphere,the chemical reactions occurring at various stages took remarkable effect on the quality of sintered compact.The potentials of oxygen and carbon in a continuous belt furnace were monitored and analyzed using an on-line thermal measuring unit consisting of thermocouple,oxygen probe,and carbon monoxide sensor.The avoidance of oxidation and decarburization promises desired micro structure and carbon content and satisfactory properties through the adjustment of technical parameters,e.g.,the composition of gases in delubrication and various sintering zones,the rate of gas inlet,and cooling rate.