Maximum Nitrogen Solubility Research Articles

Temperature dependence of nitrogen solubility in bridgmanite and evolution of nitrogen storage capacity in the lower mantle

Relative nitrogen abundance normalized by carbonaceous chondrites in the bulk silicate Earth appears to be depleted compared to other volatile elements. Especially, nitrogen behavior in the deep part of the Earth such as the lower mantle is not clearly understood. Here, we experimentally investigated the temperature dependence of nitrogen solubility in bridgmanite which occupies 75 wt.% of the lower mantle. The experimental temperature ranged from 1400 to 1700 °C at 28 GPa in the redox state corresponding to the shallow lower mantle. The maximum nitrogen solubility in bridgmanite (MgSiO3) increased from 1.8 ± 0.4 to 5.7 ± 0.8 ppm with increasing temperature from 1400 to 1700 °C. The nitrogen storage capacity of Mg-endmember bridgmanite under the current temperature conditions is 3.4 PAN (PAN: mass of present atmospheric nitrogen). Furthermore, the nitrogen solubility of bridgmanite increased with increasing temperature, in contrast to the nitrogen solubility of metallic iron. Thus, the nitrogen storage capacity of bridgmanite can be larger than that of metallic iron during the solidification of the magma ocean. Such a “hidden” nitrogen reservoir formed by bridgmanite in the lower mantle may have depleted the apparent nitrogen abundance ratio in the bulk silicate Earth.

A Study of the Effect of Alloying Elements and Temperature on Nitrogen Solubility in Industrial Stainless Steelmaking

The role of nitrogen varies in different stainless steels from a harmful impurity to a valuable alloying element. Therefore, the strict control of nitrogen content is a very important issue in the steel making process. Better understanding about the thermodynamics of nitrogen solubility is the basis for this control. The aim of this study was to determine whether the nitrogen solubility at atmospheric pressure at any given composition and temperature in an Argon Oxygen Decarburization (AOD) converter could be reliably predicted. This was done by comparing different equations for nitrogen solubility to industrial measurements of several different steel grades with a wide range of compositions and temperatures. The test set consisted of 100 heats to ensure reproducibility and sufficient variability. The focus was on examining the effect of the main alloying elements (Cr, Ni, Mo, Mn) and temperature on nitrogen solubility. Nitrogen solubility is increased most by the chromium content, followed by manganese and molybdenum, whereas nickel decreases the solubility. The interaction effect of an alloying element on nitrogen declines at increasing temperatures, resulting in a negative temperature dependence, i.e., the maximum nitrogen solubility is obtained near the liquidus temperature. The study showed that most of the examined thermodynamic equations predicted the nitrogen solubility quite well in common stainless steels and even in high alloyed steels. On the other hand, clear discrepancies were observed for steels with a high manganese content as well as with strongly deviating temperatures. Therefore, based on the present measurements and the literature data, a new equation was developed for predicting the solubility of nitrogen in a wide range of stainless steels. This equation can be coupled with the existing process models to control the AOD process.

Research on Nitrogen Solubility of Fe–Cr–Mn–V–N System Alloys in Liquid and Solid Phases

In this paper, the thermodynamic model of nitrogen solubility in vanadium nitrogen microalloyed high strength weathering steels of Fe–Cr–Mn–V–N system, according to Hillert’s model for Gibbs energy of its various phases, was established and validated. In the model, the effect of the nitrogen partial pressure on the activity coefficient and the lattice structure characteristics of the vanadium nitrogen precipitated phase were considered. It would be of guiding significance for the design and smelting of Fe–Cr–Mn–V–N system alloys. Based on the established model, the nitrogen contents in $$\delta$$ , $$\gamma$$ , $$\alpha$$ phase and liquid were calculated as a function of the temperature for Fe–Cr–Mn–V–N system alloys. The results show that: first, the maximum solubility of nitrogen in the solidification process is obviously affected by the phase transition when there is a sudden change in the solubility of nitrogen at the phase transition point. The maximum nitrogen solubility of the molten steel in the delta phase region determines whether nitrogen bubbles are formed during the solidification process. The nitrogen solubility is lowest in the solid–liquid region (about 1673 K). Secondly, the increase of Cr and Mn content is beneficial to improve nitrogen solubility in liquid and solid phases. However, the increase of V content mainly affects the nitrogen solubility in the solid phase because the nitrogen in this temperature range is precipitated in the form of vanadium nitride, as the second phase plays a role in strengthening. In addition, the alloying element Mn has a significant effect on nitrogen solubility since the Mn element is the promoting element of austenitic formation. During the solidification process, the delta ferrite region gradually reduces and may disappear with increasing Mn content. Therefore, increasing the Mn content of the alloy system in the design of alloy composition, can reduce the precipitation trend of the nitrogen during the solidification process, which can effectively avoid bubble formation in high nitrogen weathering steels. Lastly, with the increase in the nitrogen partial pressure, the solubility of nitrogen increases during the liquid and solid phases.

Studies on the functional properties of water extracts of the brown seaweeds Sirophysalis trinodis and Polycladia myrica

The functional properties of water extracts of Sirophysalis trinodis and Polycladia myrica were evaluated. Extracts contain 2.54 ± 0.21 and 2.40 ± 0.14% proteins, respectively. The maximum nitrogen solubility was observed at pH 2 in the presence of water. The fat absorption capacity of S. trinodis (2.26 ± 0.22 g oil g−1 sample) and P. myrica (2.65 ± 0.11 g oil g−1 sample) extracts was high, but the water holding capacity was low. The emulsifying capacity of extracts was not good because of the low amount of protein. The addition of 0.5 M NaCl to the extract showed the maximum emulsion stability at pH 2. Measurement of foam stability also showed that water extracts were affected by the time and pH. Differential scanning calorimetric (DSC) analysis revealed thermal transitions at about 183.45 and 180.76 °C, respectively, for S. trinodis and P. myrica. Unlike brown seaweed medicinal effects, the results showed that their water extract could not be a replacement for other vegetable extracts.

Low temperature active screen plasma nitriding of 17–4 PH stainless steel

In the present work, low temperature active screen plasma nitriding of a 17–4 PH precipitation-hardening stainless steel was investigated. The active screen technique has been used to avoid undesirable plasma concentration, edge effects and arching during D/C plasma nitriding. Solution treated (S) and Solution treated and aged (S+A) 17–4 PH stainless steel samples were Active Screen Plasma Nitrided (ASPN) for 20h at low temperature (400°C), in order to avoid undesirable precipitation of chromium nitrides. Formation of these nitrides impairs corrosion resistance of the stainless steel because they act as Cr sinks, reducing the overall amount of Cr available in the matrix. The main objective of this work was to characterize the effect of the starting conditions on the microstructure of the nitrided layers. Besides, the chemical gradients and hardness evolution during low-temperature, long term active screen plasma nitriding were also studied.A homogeneous nitrided layer was obtained along the entire surface after the nitriding process. Hardness measurements along the nitrided surface showed virtually constant hardness values, indicating that ASPN was effective to avoid edge effects. Moreover, the nitrided layer could not be etched by Villela reagent, suggesting that the corrosion resistance was not impaired.Nitrogen supersaturation after plasma nitriding was indicated for both starting conditions (S) and (S+A) by X-ray diffraction patterns, as the expanded martensite peaks were broadened and shifted to lower 2θ angles compared to the martensite peaks of the substrate. The nitrided layer of the (S+A) specimen was thicker (9.2μm) than the nitrided layer of the (S) specimen (5.7μm). Also, the maximum nitrogen content (measured by WDX) of the (S+A) specimen (3.7%) was greater than the maximum nitrogen content measured on the simply solution treated (S) specimen (1.9%). The difference in nitrogen pick-up was related to greater hardness values for the (S+A) specimens (max. Hardness 1130HV0.01) in comparison with the (S) condition (max. hardness 950HV0.01).The latter results were discussed in terms of the effect of Cu in the activity of Fe-N solid solutions. Thermo-Calc® simulations showed that when copper is in solid solution, it increases the nitrogen activity in iron-nitrogen alloys, decreasing the maximum nitrogen solubility in the steel. On the other hand, when copper is precipitated as nanoparticles in the matrix — as in the (S+A) condition — nitrogen activity decreases, implying a greater solubility of nitrogen.The substrate hardness after aging was not changed by the 400°C/20h nitriding treatment, indicating that the surface treatment can be carried out without affecting the bulk properties.

Effect of pH on the functional properties of Arthrospira (Spirulina) platensis protein isolate

In the present study, a protein isolate extracted from Arthrospira platensis by isoelectric precipitation was evaluated for its functional properties. The maximum nitrogen solubility was 59.6±0.7% (w/w) at pH 10. The A. platensis protein isolate (API) showed relatively high oil (252.7±0.3g oil/100g API) and water (428.8±15.4g of water/100g of API at pH 10) absorption capacities. The protein zeta potential, the emulsifying capacity, the emulsion ageing stability, the emulsion microstructure and the emulsion opacity as well as the foaming capacity and the foam stability were shown to be greatly affected by pH. Especially, emulsifying and foaming capacities were positively correlated to the protein solubility. Moreover, the API was able to form films when sorbitol (30% (w/w)) was used as plasticizer and to form gels when the API concentration exceeded 12% (w/w).

Nutritional and functional properties of Roselle (Hibiscus sabdariffa L.) seed protein hydrolysates

The nutritional and functional properties of Roselle seed protein hydrolysates (RSPH) were studied. Roselle seed protein isolates were digested (for 1.5 h and 3h) using pepsin followed by pancreatin. The maximum nitrogen solubility values of 94.17 and 90.8 were observed at pH 12 and pH 10 after 1.5 h and 3 h of hydrolysis, respectively. RSPH1.5 and RSPH3 exhibited a good foaming capacity of 310 and 300% respectively. Furthermore, RSPH1.5 showed the best foaming stability (300%) after 60 min compared to RSPH3 (144%) at the same time. For both hydrolysates, the amounts of essential amino acids exceeded those recommended by the Food and Agricultural Organization/World Health Organization (2007) for humans. The emulsifying capacity of RSPH1.5 was higher than that of RSPH3 90 and 100 mL/g respectively. RSPH1.5 possessed also the highest water holding and oil holding capacities compared to RSPH3. RSPH3 was more heat sensitive than RSPH1.5. The denaturation temperature for RSPH1.5 and RSPH3 were 95.80ºC and 85.93ºC respectively. Our results demonstrated that RSPH may be used wholly or partially to replace high-price materials like egg albumen and casein as well as a potential food ingredient.

Physicochemical and functional properties of a protein-rich fraction produced by dry fractionation of chia seeds (Salvia hispanica L.)

Due to possible denaturation, the protein extraction method has a major impact on its functional properties in food. Dry milling and fractionation produce less protein modification and require no effluents. The physicochemical and functional properties were evaluated for Salvia hispanica L. seed protein-rich fraction (SPRF) produced by dry fractionation. This contained (g/kg) 446.2 of protein and 345.2 of nitrogen-free extract. The maximum nitrogen solubility was 60% at alkaline pH and the minimum was 11.7% at pH 4. The emulsifying activity ranged from 50 to 56% and was independent of pH. Emulsion stability was highest (92%) at pH 8 and 10. SPRF was not a good foaming agent, with a maximum of 29% and no dependence on pH. However, foam stability was good (80%). Diluted solutions (30 and 40 g/L) exhibited high apparent viscosity (10,000 cP) with typical non-Newtonian fluid behavior. The SPRF is a potential food ingredient, particularly in foods requiring emulsion or foam stability.

Crystal and Electronic Structures, Photoluminescence Properties of Eu2+-Doped Novel Oxynitride Ba4Si6O16-3x/2Nx

The crystal structure and the photoluminescence properties of novel green Ba4-yEuySi6O16-3x/2Nx phosphors were investigated. The electronic structures of the Ba4Si6O16 host were calculated by first principles pseudopotential method based on density functional theory. The results reveal that the top of the valence bands are dominated by O-2p states hybridized with Ba-6s and Si-3p states, while the conduction bands are mainly determined by Ba-6s states for the host, which is an insulator with a direct energy gap of 4.6 eV at Γ. A small amount of nitrogen can be incorporated into the host to replace oxygen and forms Ba4-yEuySi6O16-3x/2Nx solid solutions crystallized in a monoclinic (space group P21/c, Z = 2) having the lattice parameters a = 12.4663(5) Å, b = 4.6829(2) Å, c = 13.9236(6) Å, and β = 93.61(1)°, with a maximum solubility of nitrogen at about x = 0.1. Ba4Si6O16-3x/2Nx:Eu2+ exhibits efficient green emission centered at 515–525 nm varying with the Eu2+ concentration when excited under UV to 400 nm. Furthermore, the incorporation of nitrogen can slightly enhance the photoluminescence intensity. Excitation in the UV-blue spectral range (λexc = 375 nm), the absorption and quantum efficiency of Ba4-yEuySi6O16-3x/2Nx (x = 0.1, y = 0.2) reach about 80% and 46%, respectively. Through further improvement of the thermal stability, novel green phosphor of Ba4-yEuySi6O16-3x/2Nx is promising for application in white UV-LEDs.

The initial oxidation of ε-Fe 2N 1− x: an XPS investigation

The initial oxidation of α-Fe and ε-Fe 2N 1− x , subjected either to a sputter cleaning pretreatment or a sputter cleaning plus additional annealing pretreatment, was investigated with XPS. The samples were oxidised at p O 2 =8·10 −5 Pa and temperatures ranging from 300 to 600 K. From the Fe 2p and O 1s spectra the thickness and composition of the oxide film was determined. The composition of the oxide films formed on α-Fe and on ε-Fe 2N 1− x was only a function of oxidation temperature and film thickness and was independent of the composition or pretreatment of the substrate. Analysis of the N 1s spectra provided information on the electric charge on nitrogen atoms and the depth distribution of nitrogen. A linear relation was found between the N 1s electron binding energy and the nitrogen concentration in the substrate. Upon oxidation of the iron nitride, nitrogen atoms accumulated underneath the oxide film. If the nitrogen concentration at that location exceeded the maximum solubility of nitrogen in ε-Fe 2N 1− x an additional N peak appeared in the N 1s spectrum, which indicated the formation of a nitrogen containing phase other than ε-Fe 2N 1− x at the nitride–oxide interface. For the oxygen exposures applied, the oxide-film thickness decreased with increasing nitrogen concentration in the substrate. The effect of nitrogen in the substrate on the initial oxidation was evaluated from the results.

Nitrogen-rich liquid phase regions in the LnSiAlON (Ln = Nd, Sm, Gd, Dy, Er and Yb) systems

Liquid phase regions at 1700 °C with nitrogen concentration higher than 40 eq% in the systems LnSiAlON (Ln = Nd, Sm, Gd, Dy, Er and Yb) have been determined. All the systems possess extensive liquid phase regions at 40 eq% N. With increasing nitrogen content, the liquid phase regions contract towards Si-rich compositions. The maximum solubility of nitrogen in the Ln-sialon liquids is slightly above 50 eq%, which is much higher than in Y-sialon liquid, of which the highest nitrogen concentration was determined to be slightly above 30 eq%. With increasing Z-value of rare earth elements, the liquid phase regions contract towards the Si- and Ln-rich side.

Proximate composition and functional properties of fullfat and defatted beniseed (Sesamum indicum L.) flour.

The proximate composition and functional properties of fullfat and defatted beniseed (Sesamum indicum L.) flour were evaluated. Functional properties studied were foam capacity and stability, water and oil absorption, bulk density, emulsion capacity and nitrogen solubility. Defatting increased the crude protein, ash, crude fiber, carbohydrate and mineral contents. Defatted flour showed comparatively better foam capacity and stability, water absorption and emulsion capacities but diminished bulk density and oil absorption capacity. Nitrogen solubility was pH dependent with a minimum at pH 4 and maximum at pH 8. Maximum nitrogen solubility (95%) was recorded for defatted flour while that for the fullfat flour was 60%. The proximate composition and functional properties of the samples suggest that beniseed flour would have useful application in fabricated foods.

Protein Concentrates from Unstabilized and Stabilized Rice Bran: Preparation and Properties

ABSTRACTProtein concentrates were prepared from commercially available unstabilized and heat stabilized rice bran by alkaline extraction and isoelectric precipitation. Stabilized rice bran had lower protein extractability at all particle sizes (75μ to 150μ). Both unstabilized rice bran protein concentrate (URBPC) and stabilized rice bran protein concentrate (SRBPC) showed maximum nitrogen solubility at pH 8.0. URBPC (71.5% protein) and SRBPC (50.9% protein) showed differences in amino acid contents. SDS‐PAGE of protein concentrates revealed several common components and absence of certain components from SRBPC. Protein denaturation due to commercial heat stabilization impaired extractability of proteins and influenced its quality.

Proximate composition and functional properties of raw and processed full‐fat fluted pumpkin (Telfairia occidentalis) seed flour

AbstractThe proximate composition and functional properties of raw, germinated and fermented full‐fat fluted pumpkin (Telfairia occidentalis Hook) flour were studied. Functional properties evaluated by laboratory studies were nitrogen solubility, water and fat absorption, bulk density, foam capacity and stability. Germination increased the crude protein, ash, crude fibre, iron and total phosphorus but decreased the carbohydrate and fat contents. Nitrogen solubility was pH dependent with a minimum at pH 4.0 and a maximum at pH 10.0 for the raw flour. Maximum nitrogen solubility (70%) was recorded for germinated flour, which also showed excellent fat absorption properties. Raw flour was significantly higher (P < 0.05) in water absorption capacity than the processed flours. Germination and fermentation diminished bulk density, foam capacity and stability of fluted pumpkin flour.Raw full‐fat fluted pumpkin flour showed comparatively better water and fat absorption properties than raw full‐fat soya flour. Hence it may prove to have useful applications in fabricated foods such as bakery products and ground meat formulations.

Chemical composition of Egyptian sweet potatoes

Two Egyptian sweet potato varieties were studied. The study showed considerable differences in chemical composition between the two varieties. The mineral found in the highest concentration was calcium, followed by magnesium, iron, copper, zinc and manganese. The chemical composition of sweet potato protein isolates indicated that the pulp had high protein content. The maximum solubility of nitrogen was at pH 12 and 17 amino acids were separated from the protein isolate of both peel and pulp of the Giza 69 variety and from the pulp of the Abees variety. The protein isolate of the Abees variety had only 16 amino acids.

Ceramics and glasses in the ScSiAlON system

A comparison has been made of the microstructure in β′(SiAlON) ceramics sintered with an Sc 2O 3 densifying aid with that of β′ ceramics previously fabricated with Y 2O 3. A parallel study has been made of glasses in the Sc 2O 3Al 2O 3SiO 2 system and of variations in the crystallization products with the addition of nitrogen. The purpose of this study was to explain the crystallization behaviour of the matrix glass in β′ ceramics. Crystallization of the matrix in β′ ceramics as thortveitite (ScSi 2O 7) and a silicon-substituted form of (Sc, Al) 2O 3 may be rationalized with a similar behaviour for the bulk glasses which contain a maximum nitrogen solubility (about 8 at.% N). The temperature of the Sc 2O 3Al 2O 3SiO 2 eutectic, on which sintering liquids are based, is higher than in the related Y 2O 3 system. This is the basis for the improved high temperature oxidation of β′ ceramics containing Sc 2O 3.

Nitrogen Contents of Iron Compacts Sintered in Atmospher of Cracked Ammonia

Nitrogen contents of iron powder compacts sintered in cracked ammonia were determined by direct chemical analysis. At the sintering temperature of 1200°C, maximum solubility of nitrogen in compacts seems to be reached at the earliest stage of sintering. Since the solubility of nitrogen in a-iron is considerably less than that in r-iron, the nitrogen content of sintered compact decreases drastically, during the relatively slow cooling from Ar3 down to 500°C after sintering. This desorption of nitrogen proceeds most rapidly at about 550°C for the low density compact, probably due to the catalytic effect of hydrogen on the inner surface of pore. In order to decrease the final content of nitrogen down to about 10 p.p.m. for the compact of 6.2 and 7.1 g/ee, the slow cooling rate below 100 and 2°C/min in the temperature range of 500-900°C are required respectively.

Pilot plant development of the alkali cooking process for cottonseed meats. I. Effect of flake, thickness and of time, temperature, and moisture content during cooking

Summary and ConclusionsResults obtained from alkaline cooking experiments show that all of the four variables studied—cooking mousture content, temperature, time and flake thickness—influenced the properties of the resultant meals in varying degrees. Under the experimental conditions used a high initial moisture content, above 18%, is necessary to lower the free gossypol content in the finished meal to less than 0.04%. When this amount of moisture is used, a plastic mass results at the beginning of the process which requires special equipment to supply the mechanical action necessary to break the pigment glands at a low temperature. In the presence of high moisture content and alkali the gossypol, which is released when the glands are ruptured, is bound to the meal. When sufficient initial moisture is present (24–31%), only traces of gossypol (0.010% or less) are found in the extracted crude oil.High temperatures in the presence of high moisture content reduce the solubility of the meal protein (in 0.02N NaOH). Under the conditions of moisture, temperature, and time of cooking used in the experiments the maximum nitrogen solubility obtained under conditions necessary to produce low free gossypol content was 64%. This differs from results obtained in previous work performed under different conditions. A probable reason for the difference is given based on the interrelationship of the three variables.The results demonstrated further that finer comminution of the raw meats by rolling to 0.005‐in. thick flakes results in lower free gossypol content in the finished meal and lower gossypol content of the oils as well as more complete removal of the oil by the filtration‐extraction procedure used.

System Zirconium-Nitrogen

Iodide zirconium was combined with calculated amounts of nitrided zirconium sponge and arc melted to prepare alloys in the 0 to 6 wt pet N region. Annealing treatments were carried out at 21 temperature levels. Metallographic examination of the heat-treated specimens permitted construction of the binary phase diagram from 0 to 6 pet N. Features of the diagram include the peritectic formation of both a and β solid solutions. The maximum solubility of nitrogen is 0.8 pet in β zirconium and 4.8 pet in a zirconium. An X-ray study of nitrided materials was made in the range 6 to 13 wt pet N region because serious nitrogen losses were experienced when attempts were made to arc melt these high nitrogen alloys.