Nitrogen Dissolution Research Articles

Diversity and Plant Growth-Promoting Properties of Rhodiola rosea Root Endophytic Bacteria.

Plants inhabiting environments with suboptimal growth conditions often have a more pronounced capacity to attract and sustain microbial communities that improve nutrient absorption and expand abiotic stress tolerance. Rhodiola rosea L. is a succulent plant of the Crassulaceae family adapted to survive in sandy or rocky soils or dry tundra. The aim of the present study was to investigate the diversity and plant growth-stimulating potential of R. rosea endophytic microbiota. Metataxonomic analysis of the bacterial diversity in the rhizome of R. rosea revealed 108 families. Among these, three families were found exclusively in the core microbiome of 1-year-old plants, while nine families were unique to the core microbiome of mature plants grown in the field for more than 4 years. Seventy-three endophytic bacteria isolates were obtained from the rhizome of R. rosea plants and were assigned into 14 distinct bacterial genera of Firmicutes (26%) or Proteobacteria (74%) phyla. Screening for functional genes related to the nitrogen cycle, phosphorus mineralisation or dissolution, and traits associated with nitrogen fixation (56% of isolates), siderophore production (40%), inorganic phosphorus solubilisation (30%), and production of indole-related compounds (51%) led to the classification of the isolates into 16 distinct clusters. Co-cultivation of 45 selected isolates with germinating Arabidopsis seedlings revealed 18 and 5 isolates that resulted in more than a 20% increase in root or shoot growth, respectively. The study results established the complexity of the succulent R. rosea endophytic microbiome and identified isolates for potential plant growth-stimulating applications.

Microstructure evolution and nitriding mechanism of Ti‐6Al‐4 V alloy in alumina‐based refractories

AbstractThe aims of this study were to explore the nitriding mechanism of Ti‐6Al‐4 V alloy in Al2O3‐based refractories. Al2O3‐based composite refractories were fabricated using Ti‐6Al‐4 V and sintered alumina as main materials, followed by nitriding at different temperatures in a nitrogen atmosphere. Phase and microstructure evolution of the products was analyzed by X‐ray diffraction and field‐emission scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy. The results reveal a multi‐stage nitridation process of Ti‐6Al‐4 V at different temperatures. At 900°C, nitridation of the Ti‐6Al‐4 V surface results in the formation of a (Ti,V)N solid solution, while Al and V migrate inward, forming intermetallic compounds Ti3Al and a‐Ti (Ti1‐x‐yVxAly) with rich Al and V. At 1100°C, nitridation of Ti3Al produces intermediate products like Ti2AlN or Ti3AlN, with continued inward migration of Al or V to form the intermetallic α2 phase of (Ti1‐xVx)3yAly in the center of the alloy particles. At 1300°C, decomposition of Ti2AlN or Ti3AlN results in the outward migration of Al atoms and the presence of AlN on the outer layer of Ti‐6Al‐4 V particles, thus forming a hollow structure. Finally, at 1500°C, the (Ti,V)N solid solution grains grow as a result of further diffusion and dissolution of nitrogen.

Ice Formation, Exsolution, and Multiphase Equilibria in the Methane–Ethane–Nitrogen System at Titan Surface Conditions

Titan is unique among the icy satellites in that it has a thick atmosphere, stable surficial bodies of liquid, and a precipitation system that promotes interactions between the two. Although Titan’s surface conditions are typically assumed to be above the freezing point temperatures of the major constituent species of the climate system (methane, ethane, and nitrogen), conditions may be sufficiently cool across parts of Titan to allow for ice formation alongside known liquid-vapor phases. In this study, we used Raman spectroscopy, visual inspection, and the CRYOCHEM 2.0 equation of state to map the appearance of first ice and to quantify the amount of nitrogen dissolution into liquid in the methane–ethane–nitrogen system along a 1.5 bar isobaric cooling path in the temperature range 80–95 K. This was with the intent of (1) determining the effects nitrogen has on the phase behaviors of the methane–ethane binary system, and (2) establishing the temperatures and ternary mixing ratios needed for ice formation on Titan’s surface. We found that ethane-rich mixtures enter a three-phase solid–liquid–vapor equilibrium and are characterized by nitrogen-rich exsolution upon freezing and ice that form at the bottom of the sample. With sufficient methane content, the mixtures cross a univariant four-phase solid–liquid–liquid–vapor boundary, which contributes to a distinct isothermal freezing point profile and ice that forms starting at the liquid–liquid interface. Our results generally agree with findings from previous studies of the methane–ethane–nitrogen system and are intended to add to our current understanding of Titan’s geochemical processes.

Enhanced growth of benthic microalgae by tablet from liquid dairy cattle manure-based anaerobic digestate

An effective strategy for utilizing anaerobic digestates is required to promote biomass power generation. We developed an anaerobic digestate tablet using liquid dairy cattle manure derived from a small mesophilic anaerobic digester installed on a dairy farm. Anaerobic digestate tablets are intended for use in the fertilization of oligotrophic coastal seas to promote primary production. The purpose of this study was to evaluate (1) the dissolution behavior of nutrients from anaerobic digestate tablets and (2) the effect of the application of anaerobic digestate tablets on the growth of benthic microalgae using a culture experiment. Batch experiments were conducted to investigate the dissolution behavior of the nutrients. Cumulative amounts of dissolved inorganic nitrogen and phosphate in the anaerobic digestate tablet ranged from 110 to 28.9 μg g−1 after 28 days. The dissolved inorganic nitrogen in the anaerobic digestate tablet was mainly ammonium nitrogen and accounted for 92.4–96.9%, which is advantageous for the growth of microalgae. The growth curve of the benthic microalga Nitzchia longissima was monitored using f/2 medium added to the anaerobic digestate tablet. The growth of Nitzchia longissima was two orders of magnitude greater than that of the positive control. The enhanced growth of Nitzchia longissima by the anaerobic digestate tablet was considered a concomitant effect of moderate dissolution of ammonium nitrogen and high affinity for benthic microalgae. In conclusion, the anaerobic digestate tablets prepared in this study have the advantage of supplying nitrogen to benthic microalgae. This study proposes a new method for utilizing anaerobic digestates.

Unveiling the inherent properties and impact of ultrafine nanobubbles in polar and alcoholic media through unsupervised machine learning and atomic insight

The presence of dissolved gas in the host medium in various industrial processes, such as the presence of oxygen and hydrogen during water splitting or carbon dioxide in fuel cells, or the dissolution of nitrogen for industrial applications, increases the probability of the formation of bubbles at nano-scale. Nanobubbles (NBs), spanning tens to hundreds of nanometres, display exceptional attributes, including remarkable stability, enduring longevity, and an impressive surface-to-volume ratio. These qualities firmly position NBs as pivotal entities with applications that extend across diverse industries, encompassing fields such as energy and chemistry. Therefore, it is crucial to have a comprehensive understanding of their inherent properties and behaviour right from the nucleation stage to grasp their distinctive traits fully. This paper focuses on the combination of data-driven and molecular dynamics simulation to provide a clear understanding of the mechanisms behind NBs nucleation and behaviour in liquids and identify their characteristics. The nucleation process of four gases in two potential liquids for hosting NBs, namely water and methanol, was investigated through scattering nitrogen, oxygen, carbon dioxide, and hydrogen in host liquids using molecular dynamics simulations. Then, high-throughput screening based on the DBSCA (density-based spatial clustering of applications with noise) algorithm was used to screen the formed NB clusters through dissolved gases in the host liquids to determine the size of formed NBs, their density, and motion over time. The findings offer unique insights, indicating that the density of the surrounding liquids is altered and decreased by formed nanobubbles, influenced by the establishment of a nanolayer. The lowest density was recorded for hydrogen and nitrogen nanobubbled methanol samples at 0.61673 and 0.68918 g/ml, respectively, and for hydrogen and nitrogen nanobubbled water samples at 0.93797 and 0.93722 g/ml, respectively. Additionally, the highest density among the scattered gases was observed in non-nanobubbled carbon dioxide methanol and water samples at 0.77724 and 0.99588 g/ml, respectively. Furthermore, the viscosity of the host liquids is influenced, particularly in the presence of high-density nanobubbles, as the highest viscosity was observed for nitrogen nanobubbled water samples at 0.00103 Pa.s.

Localized corrosion of nitrogen-doped diamond-like carbon films on the surface of 304 stainless steel

Nitrogen-doped diamond-like carbon (N-DLC) films with different nitrogen content were prepared on the surface of 304 stainless steel (SS) using plasma-enhanced chemical vapour deposition technology. Localized failure mechanisms of the N-DLC films under long-term exposure to sodium chloride solutions have been investigated. The results demonstrated that nitrogen doping significantly affected the failure behavior of the N-DLC films. When undoped, the number of pore defects in the film is high, providing a channel for the corrosive medium to attack the substrate metal. Meanwhile, due to the high internal stress within the undoped film, extensive exfoliation of the film occurred under the effect of the growth of oxides at the film-substrate interface. The DLC film on 304 SS is subject to stress corrosion cracking failure during long-term service in sodium chloride solution. However, when nitrogen doping is 10 sccm, the pH of the micro-zone solution was highly variable due to the dissolution of nitrogen in the film and the processes of formation and hydrolysis of NH4+. A large number of residual metal cations dissolved from the substrate combine with oxygen at the corrosion pits mouth to form oxides. This can aggravate the occlusion effect of the pits and severe pitting corrosion of 304 SS occurs under autocatalytic effects. The N-DLC film with 5 sccm nitrogen addition showed the excellent durability properties. The evolution mechanism of oxidation and dissolution behaviors in the presence of variations in local hydrochemistry is also discussed.

Important soil microbiota's effects on plants and soils: a comprehensive 30-year systematic literature review.

Clarifying the relationship between soil microorganisms and the plant-soil system is crucial for encouraging the sustainable development of ecosystems, as soil microorganisms serve a variety of functional roles in the plant-soil system. In this work, the influence mechanisms of significant soil microbial groups on the plant-soil system and their applications in environmental remediation over the previous 30 years were reviewed using a systematic literature review (SLR) methodology. The findings demonstrated that: (1) There has been a general upward trend in the number of publications on significant microorganisms, including bacteria, fungi, and archaea. (2) Bacteria and fungi influence soil development and plant growth through organic matter decomposition, nitrogen, phosphorus, and potassium element dissolution, symbiotic relationships, plant growth hormone production, pathogen inhibition, and plant resistance induction. Archaea aid in the growth of plants by breaking down low-molecular-weight organic matter, participating in element cycles, producing plant growth hormones, and suppressing infections. (3) Microorganism principles are utilized in soil remediation, biofertilizer production, denitrification, and phosphorus removal, effectively reducing environmental pollution, preventing soil pathogen invasion, protecting vegetation health, and promoting plant growth. The three important microbial groups collectively regulate the plant-soil ecosystem and help maintain its relative stability. This work systematically summarizes the principles of important microbial groups influence plant-soil systems, providing a theoretical reference for how to control soil microbes in order to restore damaged ecosystems and enhance ecosystem resilience in the future.

Large-scale molecular dynamics simulations of bubble collapse in water: Effects of system size, water model, and nitrogen

Molecular dynamics simulations in the microcanonical ensemble are performed to study the collapse of a bubble in liquid water using the single-site mW and the four-site TIP4P/2005 water models. To study system size effects, simulations for pure water systems are performed using periodically replicated simulation boxes with linear dimensions, L, ranging from 32 to 512 nm with the largest systems containing 8.7 × 106 and 4.5 × 109 molecules for the TIP4P/2005 and mW water models, respectively. The computationally more efficient mW water model allows us to reach converging behavior when the bubble dynamics results are plotted in reduced units, and the limiting behavior can be obtained through linear extrapolation in L−1. Qualitative differences are observed between simulations with the mW and TIP4P/2005 water models, but they can be explained by the models’ differences in predicted viscosity and surface tension. Although bubble collapse occurs on time scales of only hundreds of picoseconds, the system sizes used here are sufficiently large to obtain bubble dynamics consistent with the Rayleigh–Plesset equation when using the models’ thermophysical properties as input. For the conditions explored here, extreme heating of the interfacial water molecules near the time of collapse is observed for the larger mW water systems (but the model underpredicts the viscosity), whereas heating is less pronounced for the TIP4P/2005 water systems because its larger viscosity contribution slows the collapse dynamics. The presence of nitrogen within the bubble only starts to affect bubble dynamics near the very end of the initial collapse, leading to an incomplete collapse and strong rebound for the mW water model. Although nitrogen is non-condensable at 300 K, it becomes highly compressed and reaches a liquid-like density near the collapse point. We find that the dissolution of nitrogen is much slower than the movement of the collapsing water front, and the re-expansion of the dense nitrogen droplet gives rise to bubble rebound. The incompatibility of the collapse and dissolution time scales should be considered for continuum-scale modeling of bubble dynamics. We also confirm that the diffusion coefficient for dissolved nitrogen is insensitive to pressure as the liquid transitions from a compressed to a stretched state.

Hydrophobic durability and anti-corrosion of plasma nitriding layer: Evolution mechanisms of corrosion behavior under variations in local hydrochemistry

Mechanisms for the effects of nitrogen on the durability of hydrophobic and corrosion resistance of modified layers prepared on the surface of AH32 steel by plasma nitriding have been investigated. It was found that plasma nitriding can significantly improve the hydrophobicity of AH32 steel. All the contact angles (CAs) of the AH32 steel with 1 h, 3 h and 5 h nitriding were higher than 120°, which had excellent hydrophobicity. The acidification degree of the solution within the nitriding layer’s micro-zone was effectively reduced due to the dissolution of nitrogen. The micro-nano structures of the nitriding layers corroded severely after 15 days of exposure to NaCl solution. When the nitriding time is extended to 5 h, the acidification degree of the solution was intensified due to the enhanced blocking effect, and the nitrogen in the nitriding layer saturated that cannot provide enough nitrogen ions to offset the acidification of the solution, so the durability decreased instead. In comparison, the modified layer with 3 h nitriding in this study had the best durability and long-term service protective effect on AH32 steel.

Gas nitriding behavior of refractory metals and implications for multi-principal element alloy design

Multi-principal element alloys (MPEAs) comprise a large, flexible compositional space that enables tuning of their chemistry, structure, and properties. To facilitate the development of nitriding-based surface-enhancement strategies that harness a broad compositional space, this study examined the gas nitriding behavior of Hf, Mo, Nb, Ta, Ti, and Zr as a function of time, temperature (750 and 1000 °C), and nitriding potential (i.e. ammonia-to-hydrogen ratio). These metals were selected because they have a strong driving force to form nitrides, and appear in many promising refractory MPEA compositions. The nitriding temperatures were selected based on the phase transformation temperature of Ti and Zr, and the nitriding potentials were chosen such that all elements are expected to form nitrides. Mass gain measurements indicate that all six elements follow parabolic kinetics. The microstructure observations and quantitative microchemical analysis show formation of dense and well-adhered compound layers for Mo, Nb, and Ta. Thick diffusion zones appear in Hf, Ta, Ti, and Zr, and diffusion coefficients were fit to the composition profiles. Partial delamination of the compound layer occurred for Ti and Zr. Peak hardness values above 30 GPa are obtained in the dense compound layers, and the solute hardening of the underlying alloy is correlated with the nitrogen content. The results provide insight into the dynamics of nitride compound formation relative to interstitial dissolution of nitrogen, and are discussed in the context of MPEA composition and processing design.

Dissolution Characteristics of Ammonium and Nitrate in Soil with Bottom Ash from Biomass Power Plant

Recently, biomass power plants are increasing as an alternative energy source to reduce the carbon emissions from fossil fuels. The amount of waste from biomass power plants increases and bottom ash is generally buried in soil. However, there is little research on the dissolution characteristics of nitrogen, a macronutrient in soil, using bottom ash (BA). To evaluate nitrogen dissolution in soil with BA, we mixed BA with soil, collected leachate for 5 weeks, and measured NH4+-N and NO3--N concentration in leachate. As a results, BA reduced the leaching of NH4+-N and NO3--N by up to 18% and 38%, respectively. The decrease of NH4+-N leaching is judged to be the result of increased NH4+-N adsorption due to the high pH of the bottom ash, and these results are often confirmed in other biochar. The NO3--N leaching also decreased, but it is not related to the adsorption capacity of BA, so further research is needed. These results suggested that BA reduces the contents of NH4+-N and NO3--N in the soil effluent, which can be used as an important indicator for using bottom ash in the soil.The amount of NH4+-N and NO3--N dissolution in soil using bottom ash from biomass power plant (average and standard deviation; 3 replicate). (left) Accumulation of NH4+-N; (right) Accumulation of NO3--N.

Gas Atomization of Duplex Stainless Steel Powder for Laser Powder Bed Fusion.

Duplex stainless steel powders for laser additive manufacturing have not been developed extensively. In this study, the melts of a super duplex stainless steel X2CrNiMoCuWN25-7-4 (AISI F55, 1.4501) were atomized with different process gases (Ar or N2) at different atomization gas temperatures. The process gas N2 in the melting chamber leads to a higher nitrogen dissolution in the steel and a higher nitrogen content of the atomized powders. The argon-atomized powders have more gas porosity inside the particles than the nitrogen-atomized powders. In addition, the higher the atomization gas temperature, the finer the powder particles. The duplex stainless steel powders showed good processability during PBF-LB/M (Laser powder bed fusion). The gas entrapment in the powder particles, regardless of the gas chemistry and the gas content, appears to have a negligible effect on the porosity of the as-built parts.

The oxidation behavior of the CrFeCoNiAlx (x = 0, 1.0, and 5.0 wt%) high-entropy alloy synthesized with Al elemental powder via powder bed fusion technique at high temperatures

High-entropy alloys (HEAs) are promoted as promising materials for various applications, including those dealing with high-temperatures. It requires understanding of the oxidation at different temperatures, especially for such a technological process as additive manufacturing (AM), which is able to produce unique structure. The present work evaluates the oxidation resistance of the CrFeCoNiAl HEAs produced by AM of the blends of CrFeCoNi and Al powders at temperatures of 800 and 1000 ℃. Al forms the Al2O3 under the top Cr2O3 layer and prevents the delamination of the oxide scale at considered temperatures. Oxygen diffusion mainly occurs homogeneously through the columnar grain boundaries typical for AM materials. AlN precipitates under the Al2O3 formations were observed for the sample with the highest aluminium concentration due to dissolution of nitrogen in the as-built material.

Insulation Test of the Nitrogen Blanket Transformer under Sudden Temperature Drop

During the transformer operation, it is a common condition that the oil temperature decreases due to sudden rainstorms. Because the nitrogen layer is set to contact the transformer oil in the nitrogen blanket transformer directly, the influence of nitrogen dissolution and precipitation on the insulation characteristics is very important. In this paper, the effect of nitrogen is analyzed. First, the electrical field under the nitrogen bubble effect is simulated. Second, the sudden temperature drop situation is developed based on the reformed transformer. Last, the insulation changes are analyzed by partial discharge data. According to the analysis, the sudden temperature drop won’t influence the transformer operation.

Synergistic mechanism of nitrogen addition and dissolution on the corrosion behavior of diamond-like‑carbon films on HP13Cr stainless steel surface

Synergistic mechanisms of nitrogen addition and dissolution on the corrosion resistance and long-term protection behavior of diamond-like carbon (DLC) films prepared by plasma-enhanced chemical vapor deposition on the surface of HP13Cr stainless steel have been investigated. It was found that both nitrogen addition (at nitrogen flow rates of 0 sccm, 5 sccm and 10 sccm) and nitrogen dissolution during exposure in NaCl solution had significant effects on the corrosion behavior of the DLC films. More CN and N=C=N bonds were formed, and the size and amount of the defects in the DLC films were significantly reduced as the amount of nitrogen increased. The current density of the DLC film with 5 sccm nitrogen addition is 6.46 × 10−9 A/cm−2, which was reduced by one order of magnitude compared with the film without the addition of nitrogen. However, the current density of the DLC film with 10 sccm nitrogen addition is increased to 1.37 × 10−6 A/cm−2 when excessive nitrogen was added. When exposed for a long time, the expansion of the pores within the film was suppressed because the dissolution of nitrogen can effectively reduce the degree of acidification of the electrolyte within the pores. The DLC film with the nitrogen addition of 10 sccm had the best long-term service protective effect on the HP13Cr in the present work. The influencing mechanisms of different amounts of nitrogen on the corrosion behavior of the DLC films are also discussed.

On the role of stress in microstructure evolution during thermo-chemical surface engineering

<h2>Abstract</h2> Thermochemical surface engineering of metals is the deliberate and targeted modification of the (sub-)surface region of metals, with the aim to improve materials performance. Generally, thermochemical surface engineering is understood in terms of thermodynamics and diffusion kinetics to describe the evolution of the microstructure during chemical modification at elevated temperature. Associated with the change in composition, strains and stresses are introduced. These strains/stresses affect the thermodynamics and the kinetics of microstructure evolution. This contribution illustrates several examples from activities in the authors' research group. The following examples are covered:<ul><li>•The dissolution of nitrogen (N) or carbon (C) into austenitic stainless steels and high entropy alloys at temperatures below 725 K for N and below 825 K for C. Strong supersaturation with interstitials of the austenite leads to lattice expansion which is accommodated elasto-plastically and residual stresses of several GPas.</li><li>•Oxidizing of ZrCuAl-based bulk metallic glass (BMG) below the glass transition temperature leads to an internal oxidation zone (IOZ), consisting of nano-crystalline ZrO₂. Compressive residual stresses induce outward diffusion of "noble" elements, as for example Ag (if present) and Cu, which segregate at free surfaces. This segregation leads to crystalline metallic regions, which can provide a mechanism for self-healing of cracks.</li></ul>

Study of the Dissolution and Diffusion of Propane, Propylene and Nitrogen in Polydimethylsiloxane Membranes with Molecular Dynamics Simulation and Monte Carlo Simulation

Volatile organic compounds (VOCs) are important sources of atmospheric pollutants on account of their high recycling value. The membrane of dense silicone rubber polydimethylsiloxane (PDMS) has wide-ranging prospects for the separation and recovery of VOCs. In this study, PDMS membrane body models were established in BIOVIA Materials Studio (MS) to simulate VOCs with C3/N2 gases, and to study the structure of PDMS membranes and the dissolution and diffusion process of gas in the membranes. The free volume fraction (FFV), cohesive energy density (CED), radial distribution function (RDF), diffusion coefficient and solubility coefficient of C3H8, C3H6 and N2 in PDMS membranes were calculated, and the permeability coefficients were calculated according to these values. At the same time, the effects of temperature and mixed gas on the dissolution and diffusion of C3/N2 in PDMS membranes were investigated. The results show that the mass transfer process of C3 in PDMS membranes is mainly controlled by the dissolution process, while that of N2 is mainly controlled by the diffusion process. In a C3/N2 mixed gas system, there is a synergistic relationship between gases in the diffusion process, while there is competitive adsorption in the dissolution process. With an increase in temperature, the diffusion coefficients of the three gases in PDMS gradually increase, the solubility coefficients gradually decrease, and the overall permeability selectivity coefficients of the gases gradually decrease. Therefore, low-temperature conditions are more conducive to the separation of C3/N2 in PDMS membranes. The simulation results of the permeability selectivity coefficients of pure C3 and N2 in PDMS are similar to the experimental results, and the relationship between the micro- and macro-transport properties of PDMS membranes can be better understood through molecular simulation.

Phase relation in Ga-Al-N2 systems and nitrogen solubilities in Ga-Al melts equilibrated with aluminum nitride

The liquid phase epitaxial method has been applied using Ga-Al solutions to grow single-crystalline aluminum nitride (AlN). Understanding the solubility of nitrogen in such solutions is essential for improving the growth process; however, no solubility data have been reported. Therefore, we have developed two methods (a crucible method and a levitation method) that can be used to determine the nitrogen solubility in Ga-Al melts equilibrated with AlN. It was determined that the nitrogen solubilities in the Ga-Al melts were much lower than that in pure molten Al. Using the levitation method, the nitrogen solubility in pure molten Al was measured at 1282 and 1403 K. By combining the data obtained from both methods, the equilibrium constant and standard enthalpy of nitrogen dissolution reaction in molten Al were determined. Thermodynamic analysis of the nitrogen dissolution in Ga-Al melts was also performed to determine the activity coefficients of nitrogen in the melts.

Study on Flow Characteristics of Produced Fluid in Bohai Oilfield Cycle Steam Stimulated Heavy Oil Reservoir

It is helpful to better understand the flow state of produced fluid in different stages by studying the flow characteristics of produced fluid of cycle steam stimulation (CSS in short) heavy oil reservoirs from the reservoir to the wellhead, and to provide more research for the CSS replacement technologies for a clear direction. However, there are few studies on the flow state of produced fluids, and the mechanism understanding is not very clear. This article starts with laboratory experiments to study the factors that affect the fluidity of heavy oil in the Bohai Oilfield. It is found that temperature, water content of W/O emulsion, and shear rate have a greater effect on the viscosity of produced fluid in heavy oil reservoirs in Bohai Oilfield, while pressure and N2 dissolution have less effect on the produced fluid viscosity. Due to the different flow speeds of the produced liquid in different flow stages, the equivalent shear rates are different. Therefore, when studying the flow characteristics in different flow stages, it is necessary to consider the effect of the difference in flow velocity. The effect of pressure and nitrogen dissolution on the viscosity change of produced fluid is very small. And then, based on high-precision historical fitting by using reservoir numerical simulation, the CSS development of Bohai Oilfield was predicted. Finally, combined with the numerical simulation results and the results of laboratory experiments, a wellbottom temperature calculation plate, a viscosity plate of produced fluid flowing from reservoir to wellbore, a viscosity plate of produced fluid flowing in horizontal wellbore and a viscosity plate when produced fluid flows to the wellhead. According to the chart, the viscosity of the produced fluid at different development stages and different flow positions can be judged and predicted, so that the fluidity difference of the produced fluid at different positions can be obtained, and it can provide guidance for the research on replacement technology after CSS in Bohai Oilfield.

In-situ interstitial alloying during laser powder bed fusion of AISI 316 for superior corrosion resistance

• L-PBF of a 316L admixed with 2.5 wt% Cr 2 N enhanced the Cr and N contents as compared to 316L. • A nitrogen content of 0.31 wt% in solid solution was obtained. • The parts were fully austenitic, exhibiting the favorable cellular substructure. • The enhanced nitrogen content improved corrosion resistance and hardness as compared to 316L. • The results show an alternative to manufacturing of high nitrogen steels. The present work explores for the first time additive manufacturing of powder mixtures consisting of Chromium Nitride (Cr 2 N) and AISI 316L with laser powder bed fusion (L-PBF). The addition of 2.5 wt% Cr 2 N to an AISI 316L powder resulted in the successful dissolution of both chromium and nitrogen into a fully austenitic stainless steel microstructure. The nitrogen content was augmented from 0.09 wt% in the as-delivered AISI 316L powder to 0.31 wt% in the L-PBF built part, causing a slight expansion of the austenite lattice. Elongated austenite grains with an internal cellular substructure were obtained in both the Cr 2 N modified 316L and the 316L specimens manufactured by L-PBF. The addition of nitrogen (and chromium) from Cr 2 N resulted in a Vickers hardness increase of about 40 HV 0.1 , mainly by interstitial solid solution strengthening. The modification of 316L by the addition of Cr 2 N significantly improved the corrosion resistance. The improved hardness and corrosion resistance while retaining the manufacturability and cellular microstructure illustrate the potential for modifying the composition and properties of L-PBF 316L with targeted dosing with Cr 2 N powders.