Total Oxygen Content Research Articles

Effect of Al2O3 content on metallurgical characteristics of refining slag

The metallurgical effects of Al2O3 in CaO–Al2O3–SiO2–MgO system slag on the desulfurisation ability, inclusions and steel cleanliness were investigated using thermodynamic calculations, laboratory experiments and industrial tests. The results indicate that: with a decreasing Al2O3 content in top slag and with the slag basicity remaining constant, the calculated aCaO (activity of CaO), Cs (sulphide capacity) and of the slag increase; the measured total oxygen content decreases, inclusion number and area decrease, and the average content ratio, of inclusions increases. Compared with the steel refined using conventional desulfurisation slag N2 (B (basicity): 7.0, Al2O3:30%), the steel refined using slag N1 (B: 4.5, Al2O3:20%) gives a lower sulphur content, and the inclusions contain more MgO and less Al2O3 and contain a certain amount of SiO2. The Al2O3 content has a great effect on the metallurgical characteristics of the refining slag.

Effect of slag composition on the cleanliness of 28MnCr5 gear steel in the refining processes

The equilibrium reaction between CaO—Al2O3—SiO2—MgO slag and 28MnCr5 molten steel was calculated to obtain the suitable slag composition which is effective for decreasing the oxygen content in molten steel. The dissolved oxygen content [O] in molten steel under different top slag conditions was calculated using a thermodynamic model and was measured using an electromotive force method in slag–steel equilibrium experiments at 1873 K. The relations among [O], the total oxygen content (T.O), and the composition of the slag were investigated. The experimental results show that both [O] and T.O decrease with decreasing SiO2 content of the slag and exhibit different trends with the changes in the CaO/Al2O3 mass ratio of the slag. Increasing the CaO/Al2O3 mass ratio results in a decrease in [O] and an increase in T.O. To ensure that T.O ≤ 20 ppm and [O] ≤ 10 ppm, the SiO2 content should be controlled to <5wt%, and the CaO/Al2O3 mass ratio should be in the range from 1.2 to 1.6.

Oxygenation Status in Critically Ill Newborns

Prediction of neonates' critical states outcome depending on lab test findings and clinical manifestations is one of the most important and difficult problems of modern critical care medicine. Aim of the study. To evaluate changes in lab test findings and clinical manifestations in order to create individual timelines for critically ill neonates. Material and methods. We examined 229 neonates with a gestational age of 25—42 weeks. Babies' health was assessed daily throughout their ICU stay using 105 parameters. Six patients enrolled in the study died, 220 enrolled patients survived. We analyzed 24 quantitative attributes affected by variable factor «Outcome» (according to the univariate variance analysis) that reflects early outcomes of a critical state. Results. The study demonstrated that the main characteristics reflecting the severity of patient's condition and determining the outcome of a critical state are such parameters of the oxygenation status as total blood oxygen concentration, oxygen delivery index, oxygenation index, oxygen consumption index, and arterial oxygen extraction tension. The study demonstrated that neonates with favorable outcomes presented a steady increase in the oxygenation status parameters with concurrent decrease in the oxygenation index. At the same time, neonates with unfavorable out comes presented a steady decrease in the oxygen status parameters along with a significant increase in the oxygenation index. We determined that the arterial oxygen extraction tension did not comply with the reference limits even in case of a favorable outcome. The study demonstrated that a decrease in the oxygen consumption index in the unfavorable outcome group reflects a decrease in the metabolic rate in patient and indicates a terminal state of the disease. Conclusion. The assessment of tissue oxygen consumption variations with time permits to estimate the effectiveness of the intensive care, create individual timelines, and predict outcome on an individual basis.

English

The weed Adenocalymma peregrinum that is popularly known in Brazil as “ciganinha”, belongs to the family Bignoniaceae. The only way to control this plant species in crop fields is by the application of herbicides on the stump or directly on the stem. The present study aimed to analyze the effect of glycerine in controlling A. peregrinum (MIERS) L.G.Lohmann when applied on the stem. The glycerin used as a spray application of herbicide, underwent pre-purification processes with different concentrations of phosphoric acid (85%) and was characterized for water content, sulphated ash, total glycerol, matter organic non-glycerol (MONG), methanol and pH. For the analysis of the chemical composition of the stem lignin, holocellulose, extractives, calorific value and elementary quantitative determination of C, N, H, S were determined, as well as the total content of oxygen from the stem. The field work was installed at the town of Alvorada-TO, following the randomized complete block design with six treatments and four replications. Results show that the stem of A. peregrinum contains a significant amount of nitrogen, compared to other species, and high lignin content which makes it the most resistant species. The use of glycerin combined to the herbicide (picloram and triclopyr), was not efficient when compared to diesel oil. It was observed that the glycerin has potential as a vehicle for applying herbicides, leaving much to the development of new studies to make changes in its physicalchemical characteristics. Key words : Weeds, pastures, management, Adenocalymma peregrinum.

Solid-Sampling Electrothermal Vaporization Inductively Coupled Plasma Optical Emission Spectrometry for Direct Determination of Total Oxygen in Coal.

A new analytical method for direct determination of total oxygen contents in eight coal samples of the Argonne Premium Coal (APC) series and in the NIST SRM 1632d is presented. The development of a suitable calibration procedure, optimization of measurement conditions, and the application of a tailored data processing for handling of plasma effects and high blanks enable the quantification of oxygen simultaneously with other trace, minor, or major elements in whole coal samples by means of electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP OES). For comparison, the oxygen contents were determined by a direct oxygen analyzer. The obtained oxygen values of the APC and the reference material NIST SRM 1632d were compared to data in the literature. The precision of the ETV-ICP OES was within ±3.5%, and the recovery better than 92%. With this good accuracy, the developed direct solid sampling method ETV-ICP OES is well suited for the fast determination of oxygen in coals, varying in rank from lignite to semianthracite, in a content range of about 100 ppm up to 27% using 1.5 mg sample weight. This direct analysis method represents an accurate, advantageous alternative to currently used methods for estimation of total oxygen contents in coals.

Effects of Non-stoichiometry in Eu–Ba–Cu–O Systems

Structural, electrical, and thermal properties of a series of superconductors Eu\(_{1+x}\)Ba\(_{2-x}\)Cu\(_{3}\)O\(_{7-\delta }\) where \(x=0\), 0.03, 0.05, 0.1, and 0.2 were investigated. According to the X-ray powder diffraction at room temperature, all the samples are single phase. Eu\(_{1+x}\)Ba\(_{2-x}\)Cu\(_{3}\)O\(_{7-\delta }\) takes on an orthorhombic–tetragonal (O–T) phase transition for \(x=0.2\). Corresponding to the O–T phase transition, the superconducting critical temperature \(T_{\mathrm{c}}\) decreases rapidly with Eu content. Thermogravimetric analysis was used to investigate the total oxygen content by determining the weight loss in oxygen atmosphere.

Fatigue Life Improving of Drill Rod by Inclusion Control

Abstract Large and hard inclusions often deteriorate the service performance and reduce the fatigue lifetime of drill rods. In this paper, the main reasons of the rupture of drill rods were analyzed by the examination of their fracture and it is found that the large inclusions were the main reason of breakage of rod drill. The inclusions were high of Ca content or Al2O3 rich. Smaller and better deformability inclusions were obtained by the optimization of refining slag, calcium treatment process and the flow control devices of tundish. Results of industrial experiment after optimization show that total oxygen content of drill rods decreased by more than 50%, macro-inclusions weight fraction decreased from about 4 mg/10 kg to about 0.3 mg/10 kg and the micro-inclusions average size decreased from 6 to 3.6 μm. The average using times of drill rods after optimization were increased by about 60%.

Technological aspects of using a carbon–fluorine-containing addition in submerged-arc welding

The technological aspects of adding carbon–fluorine-containing additions to AN-348, AN-60 and AN-67 fluxes in welding 09G2S steel are investigated. It is shown that the addition decreases the total oxygen content of the welded joint, lowers the degree of contamination with oxide non-metallic inclusions and the level of gas saturation of the weld metal, and increases the mechanical properties and impact toughness of the welded joints. The carbon concentration of the welded joint remains similar to that of the parent metal.

Laboratory Study on Prevention of CaO-Containing ASTM “D-Type” Inclusions in Al-Deoxidized Low-Oxygen Steel Melts During Basic Slag Refining

Present work was attempted to explore the possibility of preventing CaO-containing inclusions in Al-deoxidized low-oxygen special steel during basic slag refining, which were known as ASTM D-type inclusions. Based on the analysis on formation thermodynamics of CaO-containing inclusions, a series of laboratory experiments were designed and carried out in a vacuum induction furnace. During the experiments, slag/steel reaction equilibrium was intentionally suppressed with the aim to decrease the CaO contents in inclusions, which is different from ordinary concept that slag/steel reaction should be promoted for better control of inclusions. The obtained results showed that high cleanliness of steel was obtained in all the steel melts, with total oxygen contents varied between 0.0003 and 0.0010 pct. Simultaneously, formation of CaO-containing inclusions was successfully prohibited, and all the formed oxide inclusions were MgO-Al2O3 or/and Al2O3 in very small sizes of about 1 to 3 μm. And 90 pct to nearly 98 pct of them were wrapped by relative thicker MnS outer surface layers to produce dual-phased “(MgO-Al2O3) + MnS” or “Al2O3 + MnS” complex inclusions. Because of much better ductility of MnS, certain deformability of these complex inclusions can be expected which is helpful to improve fatigue resistance property of steel. Only very limited number of singular MnS inclusions were with sizes larger than 13 μm, which were formed during solidification because of. In the end, formation of oxide inclusions in steel was qualitatively evaluated and discussed.

Hydrothermal functionalization of ordered mesoporous carbons: The effect of boron on supercapacitor performance

Hierarchical carbons with different boron contents (from 0.42 to 2.37 wt.%) were prepared by combination of soft-templating and hydrothermal approaches. This newly developed strategy enables adequate control of the chemical state of the boron functionalities in carbon materials since the self-generated pressures favour B–C bond formation. The total content of oxygen increases simultaneously with the boron content, and its speciation is also influenced by the boron chemical state distribution: the presence of C–B–C (BC3 and BC2O) species induces the oxidation of phenols to carbonyls. The electrochemical performance of the prepared carbons was tested in a three-electrode cell configuration (1 M H2SO4) showing good specific capacitances per BET specific surface area (20–36 μF/cm2). The presence of boron on the carbon backbone improves both the charge propagation and the pseudocapacitive properties. Nevertheless, the electrochemical properties are only enhanced up to some level of boron doping (around 1.8 wt.%). A two-electrode supercapacitor built with a carbon prepared by a mild hydrothermal synthesis (50 °C during 28 h) delivered energy densities similar to those of commercial activated carbons. This could lead to high volumetric capacitance, since the boron doped carbons present much higher density.

Examinations of the process of hard coal and biomass blend combustion in OEA (oxygen enriched atmosphere)

The benefits of oxygen enrichment have been demonstrated in a variety of industrial combustion applications, but to date no implementation of oxygen enrichment in boilers has been reported, primarily due to their already high thermal efficiencies and a very large scale of such systems, which require significant amounts of oxygen. But recently, oxygen combustion in boilers has become one of the CCS technologies which can be an effective tool for reducing greenhouse gases emissions, and oxygen enriched combustion is suitable for low-calorific fuels, including biomass.This paper analyses the use of oxygen enrichment in a furnace for co-firing of different kinds of biomass with hard coal in terms of emission and burnout impact (LOI). As a part of this research, the effect of injection oxygen mode and total oxygen concentration on the flue gas emission (SO2, NOx) and burnout from co-firing of straw and wooden biomass in different proportions (20% and 40%) with hard coal were studied. The co-firing tests were carried out in an isothermal flow reactor. One of the benefits from the OEA (oxygen enriched atmosphere) technology is more effective separation of CO2 owing to the higher CO2 concentration in the flue gas. The additional advantage of the OEA combustion technology in comparison with oxy-fuel combustion is that the OEA process needs lower O2 purities and therefore it is cost-effective.Experimental tests on co-firing of 20% straw-hard coal blend were conducted in oxygen enriched (up to 25 and 30%) atmospheres with three variants of O2 injection modes. NOx, SO2 emissions and burnout for the various atmospheres in the combustion chamber were studied. Moreover, co-firing tests were performed with 40% share of wooden biomass to examine the effect of the biomass share and a type on emission of NOx and SO2 in OEA. The two O2 injection modes were investigated.In each case, the emission of SO2 increases alongside an increase of oxygen concentration in atmosphere. However, the experimental results show that stable and relatively low SO2 emission and low NOx emission can be achieved for OEA when oxygen is supplied to the primary stream of air. Also, minimal LOI (loss on ignition) is obtained for OEA I+. The supply of oxygen to the secondary oxidizer stream into the burner results in highest NOx emission only in the case of OEA30. It can be therefore concluded that both the oxygen enriched atmosphere and the O2 injection mode affects NOx emission.

INFLUENCE OF INTRODUCTION OF CARBON-FLUORINE CONTAINING ADDITIVES IN AN-67 FLUX ON PROPERTIES OF METAL WELDS IN 09G2S STEEL

Experimental study of the effect of introduction of carbon-fluorine containing additives in AN-67 flux welding of 09G2S steel. It is shown that the use of supplements reduces the total oxygen content in the weld, reduces pollution by oxide non-metallic inclusions and the level of gas saturation of the weld metal, increases required mechanical properties and toughness of the weld. The concentration of carbon in the weld remains at the base metal.

New carbon-fluorine additives for welding fluxes

The influence of a carbon-fluorine additive in AN-348, AN-60, and AN-67 oxidative flux on the welding of 09Γ2C steel and in OK Flux 10.71 basic aluminate flux on the welding of 10XCHД steel is studied experimentally. The composition of the additive is as follows: 14.01–22.72% Al, 13–22.04% F, 13.16–21.34% C, 8.27–13.4% Na, 0.09–0.14% K, 0.66–1.09% Ca, 26.11–42.35% SiO2, 1.15–1.86% FeO, 0.07–0.12% MnO, 0.001–0.1% MgO, 1.47–2.38% S, and 0.03–0.05% P. The experiments show that the use of carbon as the reducing agent is optimal in terms of preventing the formation of nonmetallic inclusions in the weld seam, since its gaseous compounds CO and CO2 are easily captured and do not introduce nonmetallic inclusions in the weld seam. With 4–6% carbon-fluorine additive in the fluxes, the total oxygen content in the seam falls. When using the proposed additive, the mechanical properties and the impact strength at negative temperatures are improved on account of the lower content of nonmetallic inclusions (oxides) in the weld seam. The carbon concentration in the weld seam remains the same as in the basic steel.

Improvement of Hydrogen Permeability of Pd-Gd Film by Removal of Inclusion Particles – Part 1: Removal of Inclusion Particles

It was hard to make a thinner film of hydrogen permeable alloy by rolling when small nonmetallic inclusion particles with the size of 5 to 30 μm were present in the alloy. For this reason, the removal of nonmetallic inclusion particles from Pd-Gd alloy were examined using various fluoride fluxes. In the experiments on the removal of nonmetallic inclusion particles from Pd-7 to 16 mass% Gd alloys, the lowest total oxygen content was obtained by the addition of GdF3 flux.

THE INFLUENCE INVESTIGATION OF THE INTRODUCTION OF CARBON-FLUORINE CONTAINING ADDITIVES IN FLUX OK 10.71 ON THE PROPERTIES OF 10HSND STEEL WELDS

The experimental study of the effect of carbon-fluorine containing additives in flux OK 10.71 for 10HSND steel welding has been carried out. The studies have shown, that the additive in the composition of an aluminate-base flux has a positive effect on the weld quality. It has been found out that using carbon-fluorine containing additives in an amount of 4 and 6 % in OK 10.71 flux by 10HSND steel welding the total oxygen content in the weld decreases, but the value of required mechanical properties and the impact viscosity at low temperatures increase, at the expense of reducing the impurity of the weld by oxide nonmetallic inclusions, besides the carbon concentration in the welds remains at the carbon concentration level of base metal.

Assessment of inclusion analysis via manual and automated SEM and total oxygen content of steel

The search for increasingly cleaner steels has heightened the demand for additional analysis techniques, especially for the evaluation of inclusions in steel where greater cleanliness is required. A range of factors should be taken into account when selecting a particular method, in accordance with analysis objectives and in order to maximize the reliability of results. Although statistical techniques make it possible to correlate data from smaller samples with entire heats of steel, some methods are more suited to evaluating different inclusion profiles. The objective of this study was to evaluate the main characteristics of certain techniques used to study inclusions. Two of the primary methods for direct inclusion analysis of solid steel are metallographic techniques and chemical analysis, with total oxygen content used as an indirect inclusion measurement. A search of the literature identified the main advantages and disadvantages of each method, as well as the primary limitations for their use. This makes it easier to determine the most suitable methods for carrying out the desired analysis.

3D numerical study of tumor blood perfusion and oxygen transport during vascular normalization

The changes of blood perfusion and oxygen transport in tumors during tumor vascular normalization are studied with 3-dimensional mathematical modeling and numerical simulation. The models of tumor angiogenesis and vascular-disrupting are used to simulate “un-normalized” and “normalized” vasculatures. A new model combining tumor hemodynamics and oxygen transport is developed. In this model, the intravascular-transvascular-interstitial flow with red blood cell (RBC) delivery is tightly coupled, and the oxygen resource is produced by heterogeneous distribution of hematocrit from the flow simulation. The results show that both tumor blood perfusion and hematocrit in the vessels increase, and the hypoxia microenvironment in the tumor center is greatly improved during vascular normalization. The total oxygen content inside the tumor tissue increases by about 67%, 51%, and 95% for the three approaches of vascular normalization, respectively. The elevation of oxygen concentration in tumors can improve its metabolic environment, and consequently reduce malignancy of tumor cells. It can also enhance radiation and chemotherapeutics to tumors.

Physical and Chemical Properties and Accelerated Aging Test of Bio-oil Produced from in Situ Catalytic Pyrolysis in a Bench-Scale Fluidized-Bed Reactor

In situ catalytic upgrading is a promising technique to improve the properties of bio-oil because the bio-oil produced from the conventional method has several negative attributes, such as low heating value and highly acidic nature, and is also unstable during storage. In this study, the catalytic effect of CaO, MgO, and ZSM-5 as in situ upgrading catalysts during biomass pyrolysis was studied in a fluidized-bed reactor. Southern pine sawdust was subjected to pyrolysis with inert bed material (quartz sand) and subsequently with the catalysts. The quality of bio-oil obtained was compared to the baseline values (i.e., with the use of sand as bed material without any catalyst) in terms of its chemical composition, heating value, viscosity, pH, total acid number (TAN), and oxygen and water contents. The use of CaO resulted in an improvement in pH (2.39–3.98) and TAN (88.9–46.6) of the bio-oil when compared to the results when using only sand. In comparison, MgO was a mild catalyst because it altered the bio-oil quality slightly, while ZSM-5 had no effect on the acid content in bio-oil, although it produced bio-oil with the least oxygen content at a significantly lower yield and higher water content (38.5%). In terms of chemical composition, the catalysts exhibited different behaviors to various groups of compounds. Anhydrosugars were reduced by all of the catalysts tested to different extents, but CaO significantly altered the quality of bio-oil by reducing organic acids, while CaO and ZSM-5 reduced the abundance of phenolic compounds with a higher oxygen content. An accelerated aging test was performed to compare the efficacy of these in situ catalysts on improving the stability of bio-oil, and it was observed that the bio-oil produced using CaO was the most stable when compared to the baseline and other catalytic bio-oils tested in this study.

Effects of pyrolysis temperature and heating time on biochar obtained from the pyrolysis of straw and lignosulfonate

In this study, the effects of pyrolysis temperature and heating time on the yield and physicochemical and morphological properties of biochar obtained from straw and lignosulfonate were investigated. As pyrolysis temperature increased, pH, ash content, carbon stability, and total content of carbon increased while biochar yield, volatile matter, total content of hydrogen, oxygen, nitrogen and sulfur decreased. The data from scanning electron microscope image and nuclear magnetic resonance spectra indicated an increase in porosity and aromaticity of biochar produced at a high temperature. The results showed that feedstock types could also influence characteristics of the biochar with absence of significant effect on properties of biochar for heating time.

Effect of magnesium addition on inclusions in H13 die steel

The effect of magnesium addition on the number, morphology, composition, size, and density of inclusions in H13 die steel was studied. The results show that the total oxygen content in the steel can be significantly decreased to 0.0008wt%. Al2O3 and MnS inclusions are changed into nearly spherical MgO·Al2O3 spinel and spherical MgO·MgS inclusions, respectively. The number of inclusions larger than 1 μm decreases and the number of inclusions smaller than 1 μm increases with increasing magnesium content. V(N,C) precipitates around MgO·Al2O3 and MgO·MgS inclusions during solidification of liquid steel. The densities of MgO·Al2O3 spinel inclusions are lower than that of alumina inclusions. With increasing magnesium content in the Mg-containing inclusions, the density of inclusions decreases, leading to the improvement of inclusion removal efficiency.