Total Oxygen Content Research Articles

Effect of Reoxidation on Inclusions Characteristic During Casting in Al‐Killed Steel Containing Rare Earth

To investigate the effect of reoxidation on inclusions characteristic during casting in Al‐killed steel containing rare earth, two industrial heats, including one of steady casting and the other of reoxidation, are performed with sampling from Rheinstahl Heratus, tundish, submerged entry nozzle, and slab. In the present study, air absorption occurs at the submerged entry nozzle and caused the reoxidation of molten steel. As a result, the number of inclusions increases significantly, and nearly spherical Ce2O2S inclusions are transformed to clustered‐like CeAlO3, which increases the average size of inclusions from 3.92 to 9.21 μm, thereby resulting in serious nozzle clogging and slab defects. The results of thermodynamic calculation show that Ce2O2S is transformed to CeAlO3 with total oxygen content increases under different Ce additions, and this transformation of inclusions can be inhibited by controlling the value of [Ce]/[O] above 2.12. Based on the experimental results and the theoretical analysis, the evolution mechanism of inclusions during reoxidation is clarified. This study can provide theoretical guidance to alleviate the harm of reoxidation to Al‐killed RE‐steel from the inclusion‐controlling perspective.

Analytical control for the content of small amounts of oxygen in aluminum nitride powders using a «Metavak-AK» analyzer

A method for prompt and reliable control of low oxygen content in aluminum nitride powder using a modern gas analyzer «Metavak-AK» operating in automatic mode and never used previously for this object is presented. Aluminum nitride was obtained under conditions of pilot production at ISMAN by the method of self-propagating high-temperature synthesis (SHS). A program for operation of a «Metavac-AK» analyzer has been developed for oxygen determination in AlN samples and optimal conditions of analysis were specified: reductive melting of a sample in a graphite crucible at a furnace temperature of 2700°C in the presence of a combined Sn/Ni flux in a helium flow. The total oxygen content in aluminum nitride powders and the relative standard deviation ranged within 1.01 – 1.18% and 1.75 – 9.87%, respectively.

Diesel blends produced via emulsification of hydrothermal liquefaction biocrude from food waste

Hydrothermal liquefaction (HTL) is a promising method for producing biocrude oil from wet biowaste. However, the complex composition of the HTL biocrude has several undesirable qualities, including high viscosity, total acid number (TAN), oxygen and nitrogen heteroatom content, and lesser higher heating value (HHV) in comparison to petroleum fuels. This study investigated the production of diesel blends and their fuel quality by emulsification of HTL biocrude with the aid of a block copolymer surfactant through centrifugation and ultrasonification. Four emulsion treatment variables were considered: biocrude fraction, surfactant fraction, retention time, and RPM (rotations per minute) for centrifuge or temperature for ultrasonic. Emulsification produced fuel blends with better HHV, viscosity, and TAN in comparison to HTL biocrude oil, and high solubility levels were achieved with surfactant addition and increased retention time. Maximum biocrude solubilities of 65.43 and 75.67 wt% were obtained for centrifugation and ultrasonification, respectively. Meanwhile, the highest HHV of centrifuge and ultrasonic emulsions was 45.39 and 45.73 MJ/kg, respectively. Emulsification led to viscosities as low as 5.91 and 6.06 mm2/s for centrifuge and ultrasonic samples, respectively. The TAN of emulsions were much lower than the biocrude: 14.18–41.31 and 16.22–50.31 mg KOH/g for centrifugation and ultrasonification, respectively. Thermogravimetric analysis, elemental analysis, combustion characteristics, and thermal properties gave further insight into the fuel quality of the emulsions and any deviations from the predicted HHV, viscosity, and TAN fuel properties, as well as comparison to ASTM specifications for biodiesel blends. The results show that emulsification of HTL biocrude could be an efficient and economical pathway for producing renewable diesel blends.

Water purification from chlorobenzenes using heteroatom-functionalized carbon nanofibers produced on self-organizing Ni-Pd catalyst

The development of effective methods for the processing of hazardous wastes containing chlorinated hydrocarbons still remains a big challenge. Herein, the approach allowing the transformation of chlorohydrocarbons into functionalized carbon nanomaterials was demonstrated for 1,2-dichloroethane (DCE) used as a model compound. Carbon nanofibers (CNF) doped with nitrogen and oxygen heteroatoms were fabricated by a joint decomposition of DCE and co-reagent (CH3CN, NH4OH, C2H5OH, and H2O). The Ni-Pd (5%) alloy was used as a catalyst precursor for the CNF synthesis. Pristine Ni-Pd alloy was found to undergo disintegration under the reaction conditions and to induce an active growth of the functionalized carbon nanofibers. The obtained CNF were shown to have a similar segmental structure of carbon filaments and to possess high specific surface area (up to 470 m2/g) and porosity (up to 0.9 cm3/g). According to X-ray photoelectron spectroscopy data, the nitrogen content within CNF samples prepared using N-comprising precursors was about 1.0–1.7 at%. The total oxygen content reaches 3.6 at%. The obtained materials were demonstrated to be attractive for the dichlorobenzene adsorption from its aqueous solutions.

Research on the control technology of Ds inclusion and Oxygen content in GCr15 bearing steel

This paper presents a method for controlling Ds inclusions and oxygen content in bearing steel produced by EAT-LF-VD-CCM process, including EAF initial refining process, LF external refining process, VD vacuum treatment process and continuous casting production process. By reasonably reducing the basicity of slag, adjusting the amount and sequence of alloy addition, the carbon content of EAF steel is appropriately increased and the temperature of steel extraction is reasonably selected. Optimize the amount of deoxidizer added in off~furnace refining, improve the basicity of refining slag, control the vacuum time, aluminum loss and stirring volume; In the continuous casting process, middle alkaline coating agent, constant drawing speed and protective pouring process are used to control and remove Ds inclusions in bearing steel. The bearing steel produced by this process can remove big sized Ds inclusions in the steel, while the total oxygen content is controlled below 7ppm.

Local Mucosal CO2 but Not O2 Insufflation Improves Gastric and Oral Microcirculatory Oxygenation in a Canine Model of Mild Hemorrhagic Shock.

IntroductionAcute hemorrhage results in perfusion deficit and regional hypoxia. Since failure of intestinal integrity seem to be the linking element between hemorrhage, delayed multi organ failure, and mortality, it is crucial to maintain intestinal microcirculation in acute hemorrhage. During critical bleeding physicians increase FiO2 to raise total blood oxygen content. Likewise, a systemic hypercapnia was reported to maintain microvascular oxygenation (μHbO2). Both, O2 and CO2, may have adverse effects when applied systemically that might be prevented by local application. Therefore, we investigated the effects of local hyperoxia and hypercapnia on the gastric and oral microcirculation.MethodsSix female foxhounds were anaesthetized, randomized into eight groups and tested in a cross-over design. The dogs received a local CO2-, O2-, or N2-administration to their oral and gastric mucosa. Hemorrhagic shock was induced through a withdrawal of 20% of estimated blood volume followed by retransfusion 60 min later. In control groups no shock was induced. Reflectance spectrophotometry and laser Doppler were performed at the gastric and oral surface. Oral microcirculation was visualized by incident dark field imaging. Systemic hemodynamic parameters were recorded continuously. Statistics were performed using a two-way-ANOVA for repeated measurements and post hoc analysis was conducted by Bonferroni testing (p < 0.05).ResultsThe gastric μHbO2 decreased from 76 ± 3% to 38 ± 4% during hemorrhage in normocapnic animals. Local hypercapnia ameliorated the decrease of μHbO2 from 78 ± 4% to 51 ± 8%. Similarly, the oral μHbO2 decreased from 81 ± 1% to 36 ± 4% under hemorrhagic conditions and was diminished by local hypercapnia (54 ± 4%). The oral microvascular flow quality but not the total microvascular blood flow was significantly improved by local hypercapnia. Local O2-application failed to change microvascular oxygenation, perfusion or flow quality. Neither CO2 nor O2 changed microcirculatory parameters and macrocirculatory hemodynamics under physiological conditions.DiscussionLocal hypercapnia improved microvascular oxygenation and was associated with a continuous blood flow in hypercapnic individuals undergoing hemorrhagic shock. Local O2 application did not change microvascular oxygenation, perfusion and blood flow profiles in hemorrhage. Local gas application and change of microcirculation has no side effects on macrocirculatory parameters.

Deoxidation and inclusion evolution of FeNi-based expansion alloy smelted by slagging method

ABSTRACT The composition of CaO-SiO2-MgO-Al2O3-CaF2 slag was designed by thermodynamic calculation of [Al]-[O] equilibrium of FeNi-based expansion alloy. On this basis, the deoxidation and inclusion evolution in the process of slagging and smelting FeNi-based expansion alloy in the medium frequency induction furnace were investigated. The results show that the oxygen content in the alloy melt is mainly controlled by the [Fe]-[O] equilibrium, and the change trend of the equilibrium oxygen content calculated by [Fe]-[O] equilibrium is consistent with the actual oxygen content. The total oxygen content of the final ingot is 45 ppm. After Al deoxidation in the melting process, the inclusions in the alloy are transformed into composite oxide inclusions rich in Al2O3 and MgO. After final deoxidation with Si-Ca alloy, the contents of Al2O3 and MgO in the inclusions decreased significantly, while the CaO content increased. And there are mainly CaO-SiO2-MgO-Al2O3 composite oxide inclusions in the ingot.

Evolution of Non-Metallic Inclusions in 27SiMn Steel

To study the evolution of non-metallic inclusions in 27SiMn steel, the 27SiMn steel produced using the LD-LF-CCM process was sampled in various stages in a steel factory. The evolutionary behavior of inclusion in various processes was systematically analyzed by scanning electron microscopy (SEM-EDS), and the total oxygen content and nitrogen content in 27SiMn steel were measured at various production steps. On the basis of the calcium treatment for 27SiMn steel, the equilibrium reactions for Ca-Al were calculated according to the thermodynamic equilibrium model. The results showed that the types of inclusions at the start of LF stations are mainly Al2O3-FeO and MnS-Al2O3. Before calcium treatment, the inclusions are mostly calcium aluminate and CaO-MgO-Al2O3. Compared with the process after soft blowing, the number density of inclusions in tundish increased by 77.88%, possibly due to secondary oxidation. From the soft blowing process to the continuous casting round billet, the inclusions translate into spherical CaO-MgO-Al2O3-SiO2, and a large number of CaS were observed. One part of the CaS precipitated separately, the other part was semi-wrapped with the composite inclusions. At the same time, calcium treatment increases the number density, mean diameter, and the area fraction of inclusions. The mass fraction of T.O. (total oxygen content) increased significantly after soft blowing, and the N content increased greatly from station to tundish. The change trend of N content in steel was basically consistent with that of T.O. content. It was necessary to prevent the secondary oxidation of molten steel during calcium treatment and the casting process. When the liquidus temperature of liquid steel is 1873 K, w[Al] = 0.022%, and w[Ca] in steel is controlled between 1.085 × 10−6 and 4.986 × 10−6, the Al2O3 inclusion degeneration effect is good.

ИЗУЧЕНИЕ СОСТАВА ПРИРОДНОГО БИТУМА НЕФТЕБИТУМИНОЗНОЙ ПОРОДЫ МЕСТОРОЖДЕНИЯ ЕСЕКЖАЛ ЮГО-ЗАПАДНЫЙ

This paper presents the study of the organic components of the petrobituminous rock of the South-Western Esekzhal deposit, depending on the depth of the petrobituminous rock and the establishment of the scope of natural bitumen depending on the quality and volume of the output of natural binder. Deposits of petrobituminous rocks of Western Kazakhstan are scattered over a significant area, for example, only in the Zhylyoi district of Atyrau region, near the city of Kulsary, there are more than 20 deposits of petrobituminous rocks. We have compiled a map showing the deposits of these oil-bituminous rocks. From the results of the experimental data obtained, it follows that with an increase in the depth of occurrence of oil-bitumen rocks, a decrease in the molecular weight from 543 to 504 a.m.u is observed. In the elemental composition of natural bitumen of the studied deposit, the carbon content varies from 81.3 to 83.1% by weight, while a clear pattern of dependence of the carbon content on the depth of occurrence has not been established. A similar pattern is observed in terms of hydrogen content (from 9.2 to 11.0% by weight). The sulfur content is from 2.4 to 4.5% by weight. The total nitrogen and oxygen content ranges from 3.2 to 5.1% by weight.

Thermal and mechanical properties of Si3N4 ceramics obtained via two-step sintering

Si3N4 ceramics were prepared using novel two-step sintering method by mixing α-Si3N4 as raw material with nanoscale Y2O3–MgO via Y(NO3)3 and Mg(NO3)2 solutions. Si3N4 composite powders with in situ uniformly distributed Y2O3–MgO were obtained through solid–liquid (SL) mixing route. Two-step sintering method consisted of pre-deoxidization at low temperature via volatilization of in situ-formed MgSiO3 and densification at high temperature. Variations in O, Y, and Mg contents in Si3N4–Y2O3–MgO during first sintering step are discussed. O and Mg contents decreased with increasing temperature because SiO2 on Si3N4 surface reacted with MgO to form low-melting-point MgSiO3 compound, which is prone to volatilize at high temperature. By contrast, Y content hardly changed due to high-temperature stability of Y–Si–O–N quaternary compound. In the second sintering step, skeleton body was densified, and the formation of Y2Si3O3N4 secondary phase occurred simultaneously. Two-step sintered Si3N4 ceramics had lower total oxygen content (1.85 wt%) than one-step sintered Si3N4 ceramics (2.51 wt%). Therefore, flexural strength (812 MPa), thermal conductivity (92.1 W/m·K), and fracture toughness (7.6 MPa⋅m1/2) of Si3N4 ceramics prepared via two-step sintering increased by 28.7%, 16.9%, and 31.6%, respectively, compared with those of one-step sintered Si3N4 ceramics.

Monitoring the gradual change in oxidation state during surface oxidation or reduction of uranium oxides by photoemission spectroscopy of the 5f states

Photoelectron spectroscopy study of the U5f emission gives valuable insight into the surface oxidation mechanism of uranium oxides. Its intensity is directly related to the electron count nf, which decreases with increasing oxidation number (U(IV): nf=2; U(V): nf=1; U(VI): nf=0). n5f can be quantified by analysing the U5f/U4f intensity ratio and using a standard of known composition. In addition, the 5f emission has a characteristic multiplet shape, directly related to n5f, which can be used to distinguish the 5f2 and 5f1 configuration of U(IV) and U(V), respectively. Three independent methods are used to determine the surface oxidation state: the U5f/U4f intensity ratio, the relative intensities of the U4f oxide shifted peaks, and the O1s/U4f intensity ratio. The first two reveal the concentration of the U in each oxide, the third indicates the total concentration of oxygen. These methods are applied to follow the surface modification of UO2 films when exposed to various oxidative conditions: molecular and atomic oxygen and water plasma at 400°C. In addition, the reduction of UO3 by atomic H is studied. Molecular oxygen oxidizes UO2 to UO2+x(x = 0.22), containing both U(IV) and U(V). Atomic oxygen also oxidizes U(IV) to U(V) at low dosages, but then continues oxidizing U(V) to U(VI) (UO3) at high dosages. Conversely, atomic hydrogen reduces UO3. In the early phase of reduction U(V) forms exclusively – no U(IV) is observed. Water plasma first transforms almost all UO2 (surface and subsurface) into U(V). With further plasma exposure the surface is oxidized to about 80% U(VI) and 20% U(V). Up to this point, a small fraction of U(IV) remains at the surface. Once it disappears, the surface oxidation stops and further water plasma exposure now leads to surface reduction into U(V) (the 5f1 peak increases again). Despite the reduction at high dosage, the O1s/U4f intensity ratio keeps increasing.

Impacts and mechanisms of nanobubbles level in drip irrigation system on soil fertility, water use efficiency and crop production: The perspective of soil microbial community

Rhizosphere hypoxia severely inhibited plant growth, reducing the crop yield and water use efficiency (WUE) in greenhouse crops. Irrigation using nanobubbles (NBs) has been an efficient method to increase crop yield and WUE by ameliorating hypoxic conditions and promoting plant growth. However, the potential effects and mechanisms of different oxygen concentrations in water enriched in nanobubbles (NBW) remain unclear. Herein, this study examined the influence of different total oxygen concentrations (TOCs, ranged between 160 and 280 mg L−1) on tomato agronomic performance, soil fertility, and the bacterial community after a two-season of NBW irrigation. The results indicated that the tomato yield, WUE, soluble sugar, and vitamin C were significantly improved by NBs, showing the trends of rising to decrease with the corresponding oxygen concentration in irrigation water. The total C (TC), organic matter (OM), available N (AN) and K (AK) in soil tended to increase and then decrease with TOC in irrigation water. NB220 obtained the highest soil OM and AN values, and NB250 obtained the highest TC and AK values. The soil bacterial community composition gradually differentiated with increasing oxygen concentration. There were significant differences in relative abundances of Proteobacteria and Nitrospirae across the six oxygen levels. The keystones in the co-occurrence network were dependent on oxygen levels. FAPROTAX results revealed that bacterial functions of methanol oxidation, N fixation, aerobic chemoheterotrophy, and cellulolysis were more abundant in NB220 treated soils, consequently resulting in better crop yield, WUE, and soil fertility. Overall, the increased abundance of taxa participating in soil nutrient turnover contributed to improved soil fertility and crop agronomic performance. Our findings provided a significant opportunity to advance the understanding of oxygen threshold during aerated irrigation, with implications for green and efficient agricultural production.

Electrochemical oxidation of 2D B, N-codoped carbon nanosheets to improve their pseudo-capacitance

Introducing redox pseudocapacitance could effectively improve the specific capacitance of carbon-based electrode materials, and is a promising way to overcome the low energy density of carbon-based supercapacitors. An in-situ electrochemical oxidation method was used to electrochemically generate active oxygen-containing functional groups for B, N co-doped carbon nanosheets to significantly increase the pseudocapacitance. Results show that the degree of oxidation, the pseudocapacitance, and the charge transfer rate of the oxidized carbon nanosheets were effectively increased by co-doping with B and N. Compared with the constant potential oxidation method, the cyclic voltammetry oxidation method was more effective in increasing the total oxygen content of the oxidized electrode and to selectively generate electrochemically active quinone groups. The oxidized electrode had a high specific capacitance of 601.5 F g−1 at a current density of 1 A g−1, retaining 74.8% of the original value at 20 A g−1, revealing a favorable rate capability. The oxidized electrode also had excellent cycle stability, retaining 92.6% of the initial capacitance after 8000 cycles at 5 A g−1.

The effect of refining time and calcium addition on the removal of oxygen, nitrogen, and hydrogen from IN713LC during vacuum induction refining

This research was intended to decrease the gas content, namely, oxygen, nitrogen, and hydrogen, in the nickel-based superalloy IN713LC using vacuum induction refining (VIR) and calcium addition. To accomplish this, the molten superalloy was subjected to individual VIR for up to 15 min, as well as a combination of VIR and calcium addition up to 0.03 wt%. Then the removal of oxygen, nitrogen, and hydrogen through the superalloy's constituent carbon and added calcium was investigated. The results showed that with increasing refining time and calcium content, total oxygen and nitrogen levels decreased continuously according to second- and first-order kinetic models, respectively. However, the addition of 0.03 wt% Ca resulted in the lowest concentration of total oxygen, and a refining time of 15 min resulted in the lowest concentration of total nitrogen and hydrogen. The remaining air in the crucible's unfilled crevices was proposed as the reason for the need for calcium addition to achieve greater oxygen removal than the carbon deoxidation process. In addition, the influence of calcium addition on the removal of Al2O3 inclusions as one of the probable mechanisms of total oxygen decrease was discussed using the phase stability diagram of the Al2O3–CaO inclusion system, which was constructed in the current study.

Surface tension of aluminum-oxygen system: A molecular dynamics study

Despite the fact that aluminum is one of the most commonly-used elements, experimental results on the value of its surface tension are largely scattered due to the high sensitivity of aluminum to the atmospheric conditions, leading to huge experimental challenges. In this study, the surface tension of pure Al and Al-O systems was studied thoroughly using Molecular Dynamics (MD) simulations. A force field that includes embedded atoms method and charge transfer ionic potential was applied to account for interatomic interactions. To complement and validate the numerical approach, the surface tension of pure aluminum at two different temperatures was also measured. A good agreement was obtained between the measured and predicted surface tension. Simulations were then performed at different temperatures (1000–2200 K) with different initial oxygen contents to elucidate the effects of well-controlled atmospheric conditions on surface tension. Our results also show that the surface tension of aluminum is sensitive to the amount of oxygen content at the surface, which depends on the total oxygen content and the temperature. At various temperatures, different amounts of oxygen atoms are needed to saturate the aluminum surface (XOSat.). A relationship between XOSat. and temperature was derived. We believe that this study can shed light on the underlying mechanisms controlling surface tension of aluminum and could offer routes to better engineer the surface properties of this liquid metal.

Plasmon-assisted MXene grafting: tuning of surface termination and stability enhancement

The properties of MXenes, new generation of 2D materials, are determined by the surface terminations, which depends on flake preparation method. Changing the surface termination chemical groups can significantly modify the MXene flake properties and functionality. However, the common methods of MXene flake surface chemistry tuning require high-energy treatments and often lead to flake damage. In this work, we propose a plasmon-assisted chemical transformation for tuning the surface chemistry and termination of MXene flakes. The plasmon resonance was directly excited on MXene flakes and induced the generation of highly reactive radicals from electrostatically absorbed iodonium salt cations, leading to immediate grafting of the created radicals to the flake edges and basal planes. We used bis-CF3-substituted iodonium salts, and subsequent analysis of the Ti3C2T x MXene flake surface composition indicated decreases in the total oxygen concentration and oxidized titanium with a simultaneous increase in the fluorine surface concentration, which was related to –C6H3(CF3)2 moiety attachment. The ability to substitute the hydrophilic oxygen-containing groups with hydrophobic and oleophilic –CF3 groups containing functional groups allows us to create a stable suspension of a MXene in nonpolar organic solvents and prepare a superhydrophobic, water-repellent and oxidation-stable conductive MXene coating.

Evolution of Nonmetallic Inclusions in GCr15 Bearing Steels During Continuous Casting Process

Industrial trials and thermodynamic calculation are carried out to systematically investigate the variation of steel cleanliness and inclusions during the reoxidation of molten steel, steady and unsteady continuous casting process of GCr15 bearing steels. Comparing with inclusions in molten steel, the content of Al2O3, CaO, CaS, and MgO of inclusions in the steady bloom is increased by 2.17%, −18.47%, 14.01%, and 2.27%, respectively, due to the reoxidation of molten steel will inhibit the transformation of inclusions. As the casting length in the first bloom increases from 2 to 9 m, the total oxygen (T.O) content reduced from 12.9 to 7.2 ppm and the number density of inclusions decreases from 15.65 to 10.97 # mm−2 with a gradual decrease in Al2O3 content. Based on thermodynamic consideration, in molten steel, the lower content of T.O, the lower Al2O3 content of inclusions. For solid steel, with the increase in content of T.O, mainly the Al2O3 content of inclusions gradually increases and the CaS content gradually decreases when the T.O content is between 4 and 8 ppm. However, the Al2O3 and CaO content of inclusions gradually increases, then the MgO and CaS contents gradually decreases when the T.O content is between 8 and 25 ppm.

A General Model to Calculate the Spin-Lattice Relaxation Rate (R1) of Blood, Accounting for Hematocrit, Oxygen Saturation, Oxygen Partial Pressure, and Magnetic Field Strength Under Hyperoxic Conditions.

Under normal physiological conditions, the spin-lattice relaxation rate (R1) in blood is influenced by many factors, including hematocrit, field strength, and the paramagnetic effects of deoxyhemoglobin and dissolved oxygen. In addition, techniques such as oxygen-enhanced magnetic resonance imaging (MRI) require high fractions of inspired oxygen to induce hyperoxia, which complicates the R1 signal further. A quantitative model relating total blood oxygen content to R1 could help explain these effects. To propose and assess a general model to estimate the R1 of blood, accounting for hematocrit, SO2 , PO2 , and B0 under both normal physiological and hyperoxic conditions. Mathematical modeling. One hundred and twenty-six published values of R1 from phantoms and animal models. 5-8.45 T. We propose a two-compartment nonlinear model to calculate R1 as a function of hematocrit, PO2 , and B0. The Akaike Information Criterion (AIC) was used to select the best-performing model with the fewest parameters. A previous model of R1 as a function of hematocrit, SO2 , and B0 has been proposed by Hales et al, and our work builds upon this work to make the model applicable under hyperoxic conditions (SO2 > 0.99). Models were assessed using the AIC, mean squared error (MSE), coefficient of determination (R2 ), and Bland-Altman analysis. The effect of volume fraction constants and was assessed by the SD of resulting R1. The range of the model was determined by the maximum and minimum B0, hematocrit, SO2 , and PO2 of the literature data points. Bland-Altman, AIC, MSE, coefficient of determination (R2 ), SD. The model estimates agreed well with the literature values of R1 of blood (R2 =0.93, MSE=0.0013 s-2 ), and its performance was consistent across the range of parameters: B0=1.5-8.45 T, SO2 =0.40-1, PO2 =30-700 mmHg. Using the results from this model, we have quantified and explained the contradictory decrease in R1 reported in oxygen-enhanced MRI and oxygen-delivery experiments. 3 TECHNICAL EFFICACY: Stage 1.

Study of the relationship among total oxygen, inclusions and fatigue properties of gear steel

In order to control non-metallic inclusions and improve fatigue performance of gear steel, the relationship among total oxygen, inclusion size and fatigue properties of gear steel was investigated. In the work, Mn–Cr system gear steels with different total oxygen contents were selected as the research objects. Inclusions and fatigue properties of gear steels with different total oxygen contents were studied by using traditional metallographic method, extreme value method and fatigue test. The experimental results demonstrates that with the decrease of total oxygen content（i.e., 0.0013%→0.0010%→0.0005%）, the number of small-size oxide inclusions in the range of 5–10 μm decreases greatly, whereas the number of large-size oxide inclusions over 10 μm has relatively little change. Meanwhile, it is found that the change of total oxygen content in different ranges has different influences on the size of maximum size oxide inclusion and fatigue properties. Reducing the total oxygen content of gear steel from 0.0013% to 0.0010% decreases the inclusion size of maximum oxide inclusion and improves fatigue resistance of materials, but these benefits do not extend to a total oxygen level of 0.0005%. Accordingly, we can conclude that no evident linear correlation exists between total oxygen content and maximum inclusion size or between the total oxygen content and the fatigue performance.

Hydropyrolysis of Residual Camellia sinensis and Its Cellulose and Lignin Fractions over Nickel Nanoparticles Confined Inside Carbon Nanotube Microreactors at Atmospheric Pressure

The potential of catalytic hydropyrolysis for the production of value-added chemicals from abundant residual biomass generated during the seasonal pruning of Camellia sinensis tea crops is evaluated. Nickel nanoparticles (∼7.2 nm) encapsulated inside the cavity of carbon nanotubes (CNTs) are prepared using an impregnation method and applied as microreactors in the catalytic hydropyrolysis of both fractionated and unfractionated biomass at atmospheric pressure. Over 86% of nanoparticles are selectively located inside the CNT channel with a Ni content of 13.4 wt % and a surface area of 129.3 m2·g–1. The influence of the catalyst/biomass ratio on the product yield and selectivity is examined, and the reaction pathways are discussed. Results reveal that the majority of oxygenated compounds are reformed into long-chain alkanes (50.5%) and aromatic hydrocarbons (33.0%) with a total oxygen content of 3.90% and a low heating value of 41.8 MJ·kg–1, comparable to commercial fuels.