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Abstract Extreme wildfires have devastating impacts on multiple fronts, and associated carbon greatly heats the earth’s climate. Whether and how to predict wildfires becomes a critical question. In this study, we find that the preceding-winter “warm Arctic-cold Eurasia” (WACE) pattern significantly enlarges the spring burned area in West Siberia. The winter WACE and accompanying snow reduction result in dryness and vegetation exposure in West Siberia in spring, increasing fire risks. A multiple linear regression model is constructed that successfully predicts the spring burned area in West Siberia one season in advance (R-squared coefficient=0.64). The same predictors also well predict the corresponding fire carbon emissions. Independent predictions for spring burned area in 2019 and 2020 are very close to observations, with a mean absolute percentage error of only 3.0%. The findings of this study provide a possibility for guarding humans against extreme wildfires and predicting sharp rises in carbon emissions.

The impact of varying F content from 4 wt% to 10 wt% on the structure and properties of non-reactive mold slag for high-Mn high-Al steel was investigated in this study. Employing a combination of techniques including a rotary viscometer, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy, the viscosity and structure of mold slag were analyzed. The findings revealed that increasing F content led to a gradual reduction in viscosity, activation energy for viscous flow, and the internal friction within the mold fluxes, consequently enhancing its fluidity. The Al–O–Al structure remained stable throughout the experimental range. The decrease in QAl2 content indicated a continuous depolymerization process, leading to the formation of free [Al2OF6] and [AlO6] structures as F content increased. At the same time, the replaced O2− ions were assimilated by [AlO4] tetrahedron, facilitating the formation [AlO6] octahedron. Consequently, the slag structure was simplified, resulting in a reduction in the degree of polymerization and viscosity.

The dissolution behavior of AlN in three CaO–Al2O3–BaO–CaF2–Li2O non-reactive mold fluxes which were designated as N1 (low break temperature), N2 (good lubrication performance), N3 (high break temperature) for high-Al steel with different requirements was explored by static method. The sizes of AlN rods after dissolving in three slags decreased to 8.35 mm, 7.90 mm, and 9.10 mm, from the initial 10 mm, resulting in 0.59 wt.%, 1.78 wt.%, 0.01 wt.% decrease in Li2O content and 1.60 wt.%, 4.33 wt.%, 0.26 wt.% increase in Al2O3 content in the slags which were in contact with AlN, respectively. The interfaces between slags and AlN rods was investigated by field emission scanning electron microscopy. The results confirmed that the widths of the element transition layer were 6.3 μm, 8.0 μm and 5.3 μm for slags N1, N2, and N3 which were in contact with AlN, respectively. Furthermore, the product at the interface close to the slag sides were Al2O3–CaO–BaO–CaF2 complexes, while close to the AlN rod sides, individual Al2O3 and AlN–Al2O3 complexes were found. The thermodynamic calculation showed that only Li2O in molten slag reacted with AlN to form Al2O3. Thus, the dissolution behavior of AlN in three slags was that AlN reacted with Li2O to form Al2O3, which then diffused into the slags and was absorbed by the slags. In addition, the slags N1 and N2 with lower initial Al2O3 content had a stronger reactivity with AlN, they have a more superior ability to dissolve AlN inclusion.

Utilizing super-concentrate for direct hydrogen reduction in pelletizing which decrease energy consumption and improve smelting quality are critical steps towards achieving the dual carbon goal. The reduction swelling behavior and its corresponding mechanism of ultra-high-grade pellets were studied from multi-dimensions combing visualization detection, micromorphological analysis, and first-principles molecular dynamics simulation in present work. The results showed that for the reduction no matter in CO or H2 atmosphere, the ultra-high grade pellets expand abnormally. Whereas the increase of SiO2 content and the selection of H2 atmosphere can effectively inhibited the reduction swelling behavior of pellets, while Al2O3 content had only a slight effect. The cause of catastrophic expansion was related to the various formation of new-born iron that it exhibited angular during CO reduction while became flatter with SiO2 addition or by H2 reduction. The simulation results were validated the accuracy since the structure and energy changes during iron oxide reduction were corresponding to the experimental observations. C and Fe mainly formed chemical bonds while H and Fe primary produced physical adsorption during FexO reduction. Combing the comprehensive effect of adsorption energy, electrostatic force, and energy change, it was tended to create iron whiskers by CO reduction contrary to H2 reduction. It was conductive to generate iron whisker after Si doped in FexO. However, the decrease of pellets RSI with SiO2 addition in H2 reduction was caused by the increase of pellet porosity, which provided space for the growth of iron whisker. With the increase of Si doping amount in CO reduction, iron whiskers gradually changed from thin to chunky, resulting in more uniform growth of iron whiskers and uniform stress, which brought about a decrease in pellet reduction expansion rate contrarily.

Abstract The observed Eurasian winter surface cooling from the 1990s to the early 2010s, which is contrary to global warming, has been extensively studied. Previous studies revealed that the surface cooling trend has significantly weakened in the past decade. Based on large‐ensemble simulations, this study reveals that the weakening of Eurasian surface cooling is primarily driven by the atmospheric internal variability, which coincides with the weakening of Arctic mid‐tropospheric warming and Eurasian mid‐tropospheric cooling. Negative Arctic Oscillation (−AO) and Ural blocking (UB) in combination dominate the intensity of Arctic mid‐tropospheric warming and Eurasian mid‐tropospheric cooling. In the future, there is a possibility that the severe Eurasian cooling trend with comparable magnitude to that during 1990–2013 may reemerge accompanied with Arctic mid‐tropospheric warming, in response to the decadal strengthening of −AO and UB. This may occur before the 2050s, when the atmospheric internal variability is able to overwhelm the effects of greenhouse gases.

Abstract Many previous studies have documented the relationship between the North Pacific Oscillation (NPO) and the weather/climate of upstream and downstream regions. However, the stability of NPO precursor signals of East Asian summer precipitation, which is important for climate prediction, has received little attention. This study identified temporal variations in the connection between the May NPO and subsequent midsummer precipitation over Northeast China (NEC) during 1961–2020. During 1986–2010, the correlation between the May NPO and midsummer precipitation over NEC was found significantly positive, whereas the relation was found statistically insignificant during 1961–1985/2011–2020. Further results indicated that the NPO stimulated a Rossby wave source over the North Pacific that was stronger during 1986–2010 than during 1961–1985/2011–2020. The Rossby wave source anomalies shifted to North America and to the North Atlantic during the subsequent June and midsummer, respectively. Consequently, a teleconnection wave train, which originated over the North Pacific, propagated eastward to North America, across the North Atlantic, and on to East Asia on the subseasonal time scale, influencing midsummer precipitation over NEC through modulation of the atmospheric circulation (e.g., horizontal wind, moisture transport, and vertical movement). Moreover, the intensified Rossby wave anomalies associated with the May NPO were attributed to the strengthened NPO, which could be related to the enhanced standard deviation of SLP over the North Pacific. Additionally, the strengthened out‐of‐phase relation between the NPO and the North Atlantic Oscillation, resulting from changes in the background circulation, partially contributed to intensification of the Rossby wave train.

It is well-known that climate warming increases air temperature and reduces cold extremes in the long-term. But internal variability strongly modulates the variability of temperature at mid- and- high latitudes, for example, causing the remarkable cooling and severe winter weather over Eurasia from the 1990s to the early 2010s. It remains unclear whether the occurrence of Eurasian cooling and cold extremes will be offset by climate warming or stimulated by internal variability in the future. Based on the Sixth phase of the Coupled Model Intercomparison Project multi-model projections for 2015–2100, this study shows that the projected probability of Eurasian cooling trend decreases with increasing greenhouse gas concentration in the long-term (i.e. 2070–2099) from 14.8% under SSP126 to 0.9% under SSP585. In the near-term (i.e. 2021–2050), however, Eurasian cooling occurrences are less influenced by different emission scenarios. Coinciding with deep Arctic warming throughout the troposphere, the projected significant Eurasian cooling exhibits similar pattern and intensity among different scenarios. The similar trend towards tropospheric anticyclone over the Arctic among different scenarios in the near-term promotes the deep Arctic warming-Eurasian cooling trend through transporting warm (cold) air into the Arctic (mid-latitudes). Moreover, winter extreme cold anomalies (i.e. −3.0–−2.0 °C) and extreme cold days (i.e. 4–6 d) over the Eurasian continent are not sensitive to emission scenarios in the near-term. In the long-term, the accelerating climate warming under high-emission scenarios significantly reduces the frequency and intensity of Eurasian cold extremes compared to low-emission scenarios. Therefore, the occurrence of Eurasian cooling trend and cold extremes in the near-term will be dominated by internal influences (e.g. Ural blocking) and will rely more on the internal variability after the mid-century if carbon neutrality goal is achieved.

Recent studies have revealed the slowed Arctic sea-ice loss, but its climate effect on the ocean system remains unclear. By examining reanalysis datasets, we illustrate a paradoxical regime shift characterized by sustained ice loss and surface salinification in the Kara–Laptev Seas (KLS) during boreal summer since 2008. A notable phase transition from surface freshening during one period (1997–2008) with rapid sea-ice melting to salinification during another period (2009–2020) with gentle sea-ice melting has been identified in the KLS. Using a mixed-layer salinity budget, we characterized quantitatively the role of ice melting in driving salinification across different seas. We show that the salinification observed post-2008 mainly arises from the weakened summer sea-ice-ocean freshwater input, particularly the localized reduction in ice volume during June–August. This recent salinification in the KLS likely maintains a relatively stable state in the thinner seasonal sea-ice prevailing in the new Arctic.

Atherosclerosis, a chronic inflammatory condition primarily affecting large and medium arteries, is the main cause of cardiovascular diseases. Macrophages are key mediators of inflammatory responses. They are involved in all stages of atherosclerosis development and progression, from plaque formation to transition into vulnerable plaques, and are considered important therapeutic targets. Increasing evidence suggests that the modulation of macrophage polarization can effectively control the progression of atherosclerosis. Herein, we explore the role of macrophage polarization in the progression of atherosclerosis and summarize emerging therapies for the regulation of macrophage polarization. Thus, the aim is to inspire new avenues of research in disease mechanisms and clinical prevention and treatment of atherosclerosis.

After the oilfield development enters the medium and high water cut stage, the fine three-dimensional description of the single sand body, the distribution rules of the remaining oil, and its main controlling factors have become the focus of research. The premise is to understand the original oil and water distribution characteristics and the important influencing factors of the reservoir. Taking the Yan 932 reservoir of Y oil area in Dingbian as an example, combined with the meandering river sedimentary model, this paper uses dense well pattern logging data to dissect single sand body on the foundation of the core and logging results. The conclusion shows that, first, Yan 932 layer is divided into two stages: Yan 932-1 and Yan 932-2, which constitute four single sand body superposition configuration modes, namely, type I, type II, type I & II, and type I/II. Second, type I & II is mainly developed in the sand body of the main channel. In the west of the main channel sand body, type I, type II, and type I/II are developed. Only type II is developed in the east of the main channel sand body. Thirdly, sedimentary microfacies, sand body thickness, sand body configuration, and structural characteristics are the key factors influencing the oil-water distribution law of the Yan 932 reservoir.

Abstract Employing a model democracy in which each model is equally weighted may lead to a poor estimation of the true uncertainty in climate projections from phase 6 of the Coupled Model Intercomparison Project (CMIP6). The improvement and increase in number of CMIP6 models compared with previous phases of CMIP indicate that both model skill and independence need to be considered to provide convincing projections. In this study, we use a weighting scheme, which weights both the skill and independence of multi‐model simulations, to efficiently constrain the large uncertainty in the projection of the timing of an ice‐free Arctic. The uncertainty‐constrained projections of CMIP6 show that the multi‐model spread of the projected first year of an ice‐free Arctic can be reduced by about 29 years under the Shared Socioeconomic Pathway (SSP)3–7.0 scenario (a regional rivalry scenario), indicating a faster tendency to an ice‐free Arctic summer than projections based solely on model democracy. A fossil‐fuel‐based development scenario (i.e., SSP5‐8.5) leads to an ice‐free Arctic before the 2070s (ranging from 2038 to 2071), while an ice‐free Arctic occurs slightly later (by ∼10 years) under the SSP2‐4.5 scenario (i.e., intermediate scenario) and the SSP3‐7.0 scenario, but is inevitable this century. The sustainable development scenario (i.e., SSP1‐2.6) is likely to prevent the occurrence of an ice‐free Arctic. Internal variability strongly affects the projection estimated by the equally weighted ensemble; however, it has a negligible impact on the results obtained by the weighting scheme, thereby indicating that the results of this study are robust and convincing.

Abstract Observations have shown subseasonal reversal of temperature anomalies between early and late winter over Eurasia, which is distinct from the seasonal mean condition. Based on the reanalysis data, the 1800‐year control simulation and the 40‐member ensemble simulations in 1920–2100 from the Community Earth System Model (CESM) Large Ensemble (CESM‐LE), this study reveals that the reversal of surface air temperature (SAT) anomalies between early and late winter is one of the dominant and intrinsic features of the Arctic‐Eurasian winter climate. Such a reversal is characterized by “colder Arctic, warmer Eurasia” in December (January–February) and “warmer Arctic, colder Eurasia” in January–February (December). Robust climate dynamic processes associated with the reversal of SAT anomalies, including subseasonal reversals of anomalies in the Ural blocking, midlatitude westerlies, and stratospheric polar vortex, are found in both reanalysis data and CESM simulations, indicating the important role of internal atmospheric variability. Further analysis reveals that the reversal of Ural blocking anomalies in late December can be a potential precursor for the reversal of SAT anomalies in late winter. The reversal of midlatitude westerly wind anomalies associated with the Ural blocking can affect upward propagation of planetary‐scale waves especially with wavenumber 1, subsequently promoting the contribution of stratospheric polar vortex to the reversal of SAT anomalies in late winter over the Arctic‐Eurasian regions. Such a troposphere‐stratosphere pathway triggered by the perturbation of tropospheric circulations is confirmed by the CESM‐LE simulations, and it may be useful for the prediction of subseasonal reversal of SAT anomalies.

Rheological behaviors of several commercial mold slags, which were designed for continuous casting of high-carbon steel, peritectic steel, and high-Al steel were studied using rotational viscometer with various rotating speeds. The crystallization rates, which were correlated with rheological behaviors, were detected by in-situ observation. The effect of steel-slag interface reaction between high-Al steel and CaO–Al2O3-based slag on the non-Newtonian fluid behaviors was also discussed. The main results demonstrated that these mold slags all belonged to pseudoplastic fluid and exhibited shear thinning characteristics. The index of flow characteristics in high temperature zone was less than 1 and fluctuated around 0.9, while in low temperature zone, n rapidly decreased from 0.9 to 0.3. The results show that the low temperature zone is more obvious than the high temperature zone for the shear thinning characteristics of the mold fluxes below the break temperature. The shear thinning was closely related to the crystallization rate and grain size of crystals precipitated within melts. Steel-slag interface reaction decreased the content of glass formers, such as SiO2 and B2O3. The crystallization capacity was enhanced, followed by a reduction of lubrication ability. It is found non-Newtonian behaviors of commercial mold slag are closely associated with their crystallization capacity, and the discussion range of viscosity temperature is more in line with the actual temperature drop range of molten flux during continuous casting, which is of great significance to understand the mechanism of shear thinning and optimize the comprehensive performances of commercial mold slags.

Tundish slag composition is of vital importance to the control of steel cleanliness. In the present study, computation of phase diagram, accompanied with steel–slag reaction, was performed to preliminarily determine the tundish slag composition for high-Al steel 38CrMoAl, and the rotating cylinder method was, then, applied to further clarify the influence of slag composition on Al2O3 dissolution into tundish slag. Thermodynamic analysis suggested that SiO2-minimized CaO–Al2O3 (wt%CaO/wt%Al2O3 = 1.0–1.4) slag with MgO

To evaluate the lubrication capacity and flaking behavior of mold slag during continuous casting, the contact angle and spreading of CaO-SiO2 and CaO-Al2O3-based mold slags on solid substrates of three steel grades were investigated systematically by the sessile drop technique. The optical basicity and viscosity were combined to clarify the relationship between melt structure and contact angle, and the Mills’ model was used to determine the work of adhesion of mold slags on steel substrates. The primary results indicated that an increasing content of Al and Mn in steel was favorable for decreasing the contact angles. The wettability of the mold slags was related to the network structure, where a more complex network structure, correlated with a larger contact angle on the solid steel surface. The separation of the low-reactive or non-reactive mold slags from the solidified shell was more difficult than that of the CaO-SiO2-based mold slags. Considering the contact angles and works of adhesion, the developed low-reactive or non-reactive mold slags could present both satisfactory lubricating capacity and flaking behavior from the strand surface.

The single snorkel refining furnace (SSRF) is widely used in secondary refining for the miniaturization of special steel. In this study, a computational fluid dynamics (CFD) model, coupled with population balance equations (PBEs), is built to describe the argon–molten steel two-phase flow in an industrial SSRF. In this simulation, bubble expansion due to the sharp variation in hydrostatic pressure and bubble coalescence and breakup are considered for the first time. The numerical results are basically consistent with the experimental observations and calculated values published in the literature for the mixing behavior and local velocity in the physical simulation and the Sauter mean bubble diameter and circulation flow rate in the industrial SSRF. The simulated results indicate that the width of bubble plume increases as the bubbles rise, and larger bubbles are formed in the center of the plume, while smaller bubbles are generated at its outer boundary. Meanwhile, the Sauter mean bubble diameter decreases gradually with rise height until reaching an equilibrium value. In addition, the circulation flow rate of molten steel is relatively independent of the initial bubble diameter. Finally, in the range of explored argon flow rates, the circulation flow rate and the refining efficiency can be enhanced as the argon flow rate is increased.

Given the problems of multiple natural microfractures developed in Chang 6 reservoir of Huaqing oilfield in Ordos Basin, the injected water flows along with the natural fractures during water injection development, resulting in low water drive recovery. The concept of volume fracturing is introduced into water injection well fracturing, and the technical idea of reconstructing the seepage field through volume fracturing of water injection well is proposed to improve the water flooding effect. On the basis of previous studies, firstly, the development of fractures and the rock mechanical properties of reservoirs are studied, and then the expansion law of volumetric fracturing fractures in the study area is analyzed. Combined with numerical simulation research, the feasibility of improving water drive by volumetric fracturing in water injection wells is demonstrated. Based on the above research, field tests of three well groups are carried out. The test shows that the volume fracturing of water injection wells can form a fracture zone along the direction of the maximum principal stress (with an average bandwidth of 56 meters), and then change the original dominant direction of water drive to realize the effective matching between fractures and injection production well pattern; the row spacing is reduced, and the effect of waterflooding is improved obviously. After the test, the average daily oil production of a single well increased from 0.6 tons to 1.0 tons, the water cut decreased from 74.6% to 42.0%. The oil recovery rate increased from 0.44% to 0.77%. The recovery increased by 5-8%.

The area of Arctic winter sea ice growth (WSIG) has expanded dramatically since winter 2008. Yet the thermodynamic and dynamic contributions to the abrupt increase in WSIG remain unclear. Here using an ice concentration budget, we characterized quantitatively the increasing WSIG and revealed the relative contributions of dynamics during 1985–2021. Ice dynamics related to ice convergence/divergence are compared in two representative regions. The northern Laptev Sea is a freezing-dominated ice growth region and is competitively driven by the ice convergence. While in northwest Beaufort Gyre (BG), the combined effects of freezing and ice divergence have both enhanced since 2008, and the dynamics contribute 84% to the significant WSIG intensification since 2008. Comparison of thermodynamic and dynamic contributions emphasized that the winter sea-ice expansion is influenced not only by winter freeze, but also by convergence/divergence relative to newly formed thinner and mobile ice. Furthermore, the amplified summer Beaufort High in the mid-2000s and its long-lasting memory of the wind-driven strengthened BG are partially attributed to the abrupt increased WSIG since 2008.

Ultra-wide slabs have a good application market and prospect, but there is still a lack of research on the flow field. To explore the characteristics of its flow field, this study built a 0.5-scale physical model of mold using Perspex. The effect of casting speed on flow field and surface flow speed was investigated by using an ink tracer experiment and contact measurement. There were various flow patterns in the ultra-wide slab mold, and they continue to transform each other. The jet momentum from the nozzle ports was diffused by colliding with the wide face, which lowered its kinetic energy and affected its subsequent diffusion. Compared with the conventional mold, the upper flow intensity of the ultra-wide slab mold was weaker, which made its liquid surface inactive and caused it to produce a flux rim or slag strip. At different casting speeds, the average flow speed distribution of the ultra-wide slab was C-shaped. When it increased from 0.9 to 1.4 m/s, the corresponding maximum average flow speed increased from 0.08 to 0.2 m/s. At the same time, the proportion of the low-flow speed zone at the most active part of the surface also gradually decreased from more than 90% to about 49%.

A thermodynamic model was proposed to calculate the activity of components in low-reactive CaO-BaO-Al2O3-SiO2-CaF2-Li2O mold flux, which was chosen to improve the castability of high Al steel, based on the ion and molecular coexistence theory. The model was indirectly validated, and the effects of the mass ratio of Al2O3/SiO2, contents of CaF2 and Li2O on the reactivity of components were discussed. The results reveal that the reactivity of mold flux attenuated with the increase in the mass ratio of Al2O3/SiO2. The decrease in reactivity was insignificant as the mass ratio was over 3.5. The steel–slag reaction experiment confirmed that the reactivity of mold flux is weakened when the content of SiO2 below 8 wt%. The reactivity of mold flux increased nearly linearly with the increase in CaF2 content, indicating that the proportion of CaF2 should be kept to a minimum in the flux. In addition, the compositional regions involving around 6 wt% Li2O should be avoided to develop low-reactive mold flux.

Based on the ERA5-Land datasets from 1981–2020, a decadal oscillation has been found in the variation of summer runoff in the middle and lower reaches of the Yangtze River Basin (MLYRB). The oscillation suggests that the MLYRB will experience increased runoff in the next few decades after 2020, which saw a record high runoff in the MLYRB. The decadal changes in summer runoff over the MLYRB under various climate change scenarios are then analyzed with direct runoff outputs from 28 general circulation models participating in the sixth phase of the Coupled Model Intercomparison Project. Given that the equal-weighted multi-model ensemble mean could not well represent the historical runoff changes in the MLYRB, in this paper we introduce a model weighting scheme that considers both the model skill and independence. It turns out that this scheme well constrains the models to represent the observed decadal changes of summer runoff. The weighted mean projections suggest that the summer runoff in the MLYRB during 2015–2100 under all warming scenarios will be higher than the present day; and 2021–2040 is likely to be a period with significantly increased summer runoff. Results of the present study have great implications for flood control and effective water resources management over the MLYRB in the future, and the weighting approach used in this paper can be applied to a wide range of projections at both regional and global scales.

Extreme cold waves frequently occur in east of China that dramatically endanger ecological agriculture, power infrastructure and human life. In this study, we found that the ‘Warm Arctic-Cold Siberia’ pattern (WACS) significantly enhanced cold waves in east of China according to daily composites from 1979 to 2018. During the winter 2020/21, a record-breaking cold wave broke out following a noticeable WACS phenomenon and induced the record-low surface air temperature at 60 meteorological stations since they were established (nearly 60 years). On 3 January 2021, the difference in temperature anomaly between the Barents–Kara Sea and Siberia reached 20 °C, the peak of winter 2020/21. With a shrinking meridional temperature gradient, the atmospheric baroclinicity weakened correspondingly. The accompanying atmospheric anomalies, i.e. the persistent Ural Blocking High and Baikal deep trough effectively transported stronger cold air than the sole impact from Arctic warming. After 4 d, the east of China experienced a severe surface air temperature decrease of more than 8 °C, covering an area of 2500 000 km ^2 . During the same winter, a record-breaking warm event occurred in February 2021, and the ‘Cold Arctic-Warm Eurasia’ pattern also appeared as a precursory signal. Furthermore, on the interannual scale, the connection between winter-mean temperature anomalies in east of China and the WACS pattern also existed and even performed more strongly in both observations and simulation data of CMIP6.

The continental shelves of the Arctic Ocean and surrounding seas contain large stocks of organic matter (OM) and methane (CH _4 ), representing a potential ecosystem feedback to climate change not included in international climate agreements. We performed a structured expert assessment with 25 permafrost researchers to combine quantitative estimates of the stocks and sensitivity of organic carbon in the subsea permafrost domain (i.e. unglaciated portions of the continental shelves exposed during the last glacial period). Experts estimated that the subsea permafrost domain contains ∼560 gigatons carbon (GtC; 170–740, 90% confidence interval) in OM and 45 GtC (10–110) in CH _4 . Current fluxes of CH _4 and carbon dioxide (CO _2 ) to the water column were estimated at 18 (2–34) and 38 (13–110) megatons C yr ^−1 , respectively. Under Representative Concentration Pathway (RCP) RCP8.5, the subsea permafrost domain could release 43 Gt CO _2 -equivalent (CO _2 e) by 2100 (14–110) and 190 Gt CO _2 e by 2300 (45–590), with ∼30% fewer emissions under RCP2.6. The range of uncertainty demonstrates a serious knowledge gap but provides initial estimates of the magnitude and timing of the subsea permafrost climate feedback.

During the continuous casting (CC) of Ti-bearing steel, a steel lump can solidify in the mold (i.e., floater steel) more easily than in the Ti-free steels. This causes severe surface defects or even a breakout. We have examined the mechanisms of floater formation during the CC of 321 stainless steel by analyzing the inclusions in the floater steel and in the 321 steel that was sampled from the mold. Additionally, we calculated the disregistry between the metallic phases and common inclusions. The mineralogy and morphology of the inclusions were examined while using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Thermodynamic calculations on the TixOy inclusions at different oxygen potentials were performed while using FactSage 7.2. Using this approach, we determined that ferrite nucleates grow on TiN and MgO inclusions following solidification, which then form micro-aggregates as a result of dynamic collisions and alliances. Analysis of the mold slag from the metallurgy stage indicated that altering the basicity and properties of the mold flux systematically might minimize the reaction between the slag and steel, which would achieve a coordinated control over lubrication and heat transfer.

The effect of nonsinusoidal oscillation at different modification ratios (α) on slag lubrication was investigated during mold oscillation. A validated and reliable multiphase model was employed, which involved flow and solidification of the molten steel and mold slag. The main results revealed that a large amount of liquid slag at the entrance of the mold–strand channel reflowed into the slag pool at the middle of the negative strip period. The phenomenon was more distinct, with an increase in the modification ratio. The modification ratio had no obvious effect on the average thickness of the liquid film at different depths below the meniscus. A modification ratio of 0.5 caused less fluctuation of the transient liquid film. Quantitative prediction of slag consumption indicated that as the modification ratio increased from 0.2 to 0.5 to 0.8, the average values were 0.278, 0.286, and 0.279 kg/m2, respectively. Shell solidification and growth near the meniscus mainly occurred when the mold was descending, which not only depended on the heat flux, but also on the liquid slag flow, the pressure driven by slag rim, and the mold oscillation. Optimization of the modification ratio of nonsinusoidal oscillation could be an alternative to delay growth of the initial shell towards the molten steel. A modification ratio of 0.5 had the least robust shell tip at the meniscus, thereby reducing entrapment of inclusions and bubbles by the shell tip.

The effect of substituting CaO with BaO and CaO/Al2O3 ratio on the viscosity of CaO⁻BaO⁻Al2O3⁻CaF2⁻Li2O mold flux system was studied by rotational viscosity method. The results showed that the viscosity increased with increasing BaO as a substitute for CaO, while the viscosity decreased with the increase in CaO/Al2O3 ratio. The viscous activation energy of the slags is from 92.1 kJ·mol−1 to 133.4 kJ·mol−1. Either the Arhenius or the Weymann⁻Frenkel equation can be applied to establish the viscosity prediction model. In this paper, the Weymann⁻Frenkel equation and a new optical basicity with regard to Al2O3 as an acidic oxide were applied to the modified NPL model for predicting the viscosity of CaO⁻BaO⁻Al2O3⁻CaF2⁻Li2O mold flux system. The estimated viscosity is in good agreement with the measured viscosity.

As an essential synthetic material used in the continuous casting of steels, mold fluxes improve the surface quality of steel slabs. In this study, a CaO-SiO2-Na2O-based low-fluorine mold flux was solidified by an improved water-cooled copper probe with different temperatures of molten flux and different probe immersion times. The heat flux through solid films and the film structures were calculated and inspected, respectively. Internal cracks (formed in the glassy layer of films during solidification) were observed. The formation and evolution of those cracks contributed to the unstable heat flux density. The roughness of the surface in contact with the water-cooled copper probe formed as films were still glassy and the roughness had no causal relationship with crystallization or devitrification. Combeite with columnar and faceted dendritic shapes were the main crystal in the film.