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We investigate the relationship between the global distribution of deep slab dips (at 250‐ to 300‐km depth) and pressure and circulation in the upper mantle. Using an analytic method to compute dynamic pressure in a 3‐D global upper mantle domain, and a force balance between slab dip, slab buoyancy, and pressure, we model dips for all major subduction zones. Overall, our models suggest that global‐scale mantle flow, as dictated by the shapes and velocities of Earth's plates and slabs, plays a fundamental role in creating the global pattern of slab dips. The dip trends of the South American and western Pacific subduction zones are controlled, in our models, by spatial variations in the dynamic pressure associated with flow. Our best fitting models produce global root mean square dip misfits of less than 10° for asthenospheric viscosities of 2.5–4.0 × 1020 Pas. This result is only obtained with a large flux of asthenosphere from upper to lower mantle at subduction boundaries, occurring on the overriding plate side of slabs, without which dips are significantly steeper than observed. This effect cannot be resolved by processes that affect only certain subduction systems and requires flux of asthenosphere into the lower mantle at subduction systems globally (or an alternative mechanism that produces more negative pressures on the overriding plate side of slabs). Upper mantle pressure fields that fit global slab dips yield negative dynamic pressure on the upper plate side of slabs, positive pressure on the subducting plate side, and an east‐to‐west pressure increase beneath the Pacific Plate. Key Points: By linking dip to mantle pressure via a force balance, we investigate global mantle flow as constrained by the Earth's slab dip distributionModels produce pressure fields consistent with Earth dips when material is down fluxed into the lower mantle on the upper plate side of slabsSlab dips provide a constraint on dynamic pressure patterns in the upper mantle [ABSTRACT FROM AUTHOR]

Carbon fluxes at the land‐atmosphere interface are strongly influenced by weather and climate conditions. Yet what is usually known as "climate extremes" does not always translate into very high or low carbon fluxes or so‐called "carbon extremes." To reveal the patterns of how climate extremes influence terrestrial carbon fluxes, we analyzed the interannual variations in ecosystem carbon fluxes simulated by the Terrestrial Biosphere Models (TBMs) in the Inter‐Sectoral Impact Model Intercomparison Project. At the global level, TBMs simulated reduced ecosystem net primary productivity (NPP; 18.5 ± 9.3 g C m−2 yr−1), but enhanced heterotrophic respiration (Rh; 7 ± 4.6 g C m−2 yr−1) during extremely hot events. TBMs also simulated reduced NPP (60.9 ± 24.4 g C m−2 yr−1) and reduced Rh (16.5 ± 11.4 g C m−2 yr−1) during extreme dry events. Influences of precipitation extremes on terrestrial carbon uptake were larger in the arid/semiarid zones than other regions. During hot extremes, ecosystems in the low latitudes experienced a larger reduction in carbon uptake. However, a large fraction of carbon extremes did not occur in concert with either temperature or precipitation extremes. Rather these carbon extremes are likely to be caused by the interactive effects of the concurrent temperature and precipitation anomalies. The interactive effects showed considerable spatial variations with the largest effects on NPP in South America and Africa. Additionally, TBMs simulated a stronger sensitivity of ecosystem productivity to precipitation than satellite estimates. This study provides new insights into the complex ecosystem responses to climate extremes, especially the emergent properties of carbon dynamics resulting from compound climate extremes. Plain Language Summary: Terrestrial ecosystems sequestrate a large amount of carbon dioxide from the atmosphere, which helps to mitigate climate warming. Climate extremes, such as droughts and heatwaves, play a significant role in determining the capacity of land ecosystems in carbon uptake. In the past decades, terrestrial biosphere models have been widely used to investigate the magnitude and variations of carbon fluxes between land and the atmosphere. In this study, we attempted to understand how model‐simulated carbon fluxes respond to climate anomalies and extremes at the global level and across regions. Analysis of model simulations showed significant spatial variations in the sensitivity of carbon fluxes to climate variations. Interestingly, concurrences of abnormal temperature and precipitation could have stronger impacts on carbon fluxes than individual temperature or precipitation extreme event. This study is important for better understanding climate extreme impacts on ecosystem dynamics and the global carbon cycle. Key Points: Impacts of temperature or precipitation extremes on carbon fluxes could be amplified due to their interactive effectsHot extremes lead to a larger carbon loss in tropics while ecosystems in the arid and semi‐arid zones show the largest sensitivity to precipitationModels simulated larger sensitivity of ecosystem productivity to precipitation than satellite product, particularly in tropics [ABSTRACT FROM AUTHOR]

Floods are dominant controls on export of solutes from catchments. In contrast, low‐flow periods such as droughts are potentially dominant control points for biogeochemical processing, enhancing spatiotemporal variation in solute concentrations, stream metabolism, and nutrient uptake. Using complementary time series (i.e., an Eulerian reference frame) and longitudinal profiling (i.e., a Lagrangian reference frame), we investigated hydrologic controls on temporal and spatial variation in solute flux and metabolism in the Lower Santa Fe River (FL, USA), where highly colored surface water mixes with exceptionally clear groundwater from springs. Gage measurements suggest groundwater inputs ranged from <1% (during extreme floods) to 86% (during extreme drought) of total discharge (Q). Mass transport of most solutes was dominated by high‐Q periods. Most solute C‐Q relationships exhibited statistically significant slope breakpoints near the transition between surface and groundwater dominance. In particular, parameters controlling water column light attenuation were chemostatic above median Q but markedly reduced at low Q. As a result, river metabolism and assimilatory nitrate (NO3−) uptake were consistently suppressed at high Q and enhanced at low Q, with greater variability in response to drivers other than water column light transmittance. Spatial variation in solute concentrations was also enhanced at low Q, induced by discrete groundwater inflow and biogeochemical processing along the reach. Contrasting reference frames yielded corroborative evidence for transport dominance at high Q, which damps spatiotemporal heterogeneity. In contrast, low‐Q periods enable localized mixing controls on solute concentrations and high rates of metabolism and nutrient processing that increase spatiotemporal variability. Plain Language Summary: Floods transport a large mass of dissolved and suspended material. A large fraction of total export occurs during these few events. However, floods reduce water clarity limiting photosynthesis and attenuate other coupled biological transformations of transported material. Rivers are far more reactive at low flow, such as during droughts. Key Points: Floods are dominant controls on solute mass transportLow Q enhances spatiotemporal variation in concentrations and rates of biogeochemical processingSupporting inferences can be made using complementary reference frames [ABSTRACT FROM AUTHOR]

Solar energetic particles are one of the main sources of particle radiation seen in space. In the first part of September 2017 the most active solar period of cycle 24 produced four large X‐class flares and a series of (interplanetary) coronal mass ejections, which gave rise to radiation storms seen over all energies and at the ground by neutron monitors. This paper presents comprehensive cross comparisons of in situ radiation detector data from near‐Earth satellites to give an appraisal on the state of present data processing for monitors of such particles. Many of these data sets have been the target of previous cross calibrations, and this event with a hard spectrum provides the opportunity to validate these results. As a result of the excellent agreement found between these data sets and the use of neutron monitor data, this paper also presents an analytical expression for fluence spectrum for the event. Derived ionizing dose values have been computed to show that although there is a significant high‐energy component, the event was not particularly concerning as regards dose effects in spacecraft electronics. Several sets of spacecraft data illustrating single event effects are presented showing a more significant impact in this regard. Such a hard event can penetrate thick shielding; human dose quantities measured inside the International Space Station and derived through modeling for aircraft altitudes are also presented. Lastly, simulation results of coronal mass ejection propagation through the heliosphere are presented along with data from Mars‐orbiting spacecraft in addition to data from the Mars surface. Key Points: Corrected particle flux measurements taken by different instruments on-board different platforms at Earth and Mars show good agreement/correlationDose calculations based on a full spectral fit to fluence indicate this was one of the 20 largest particle events of the past 45 years but still almost an order of magnitude below the largest eventsIn situ single event observations show significant increases due to the enhancements and calculations show moderate enhancements for humans at aircraft altitudes [ABSTRACT FROM AUTHOR]

Abstract: Solid oxide membrane (SOM) electrolysis process can produce high‐purity silicon from SiO2 dissolved in molten oxy‐fluoride flux at elevated temperatures. Yttria‐stabilized zirconia (YSZ), the preferred material for the oxygen‐conducting membrane for this application, is found to degrade over time upon exposure to the silica‐containing molten oxy‐fluoride flux. This YSZ degradation is caused by the acidity of the dissolved silica, especially when the optical basicity of the molten flux is lower than that of the yttria present in the YSZ membrane. To counteract this mismatch, the addition of CaO, a basic oxide, to the flux can adjust the optical basicity of the flux and successfully mitigate the YSZ membrane degradation. The detailed correlation between the rate of YSZ membrane degradation and the optical basicity of the flux is investigated by systematically testing a series of flux compositions. It is found that as the oxide optical basicity in the flux approaches that of the yttria in the YSZ, the degradation of the YSZ membrane is mitigated and essentially vanishes when the flux acidity with respected to the yttria is neutralized. This approach provides a guideline for eliminating membrane degradation during the production of silicon using the SOM electrolysis process. [ABSTRACT FROM AUTHOR]

Though the potential scope of multi‐objective genetic algorithm in the field of secondary steel making (SSM) is enormous, the useful utilization of such evolutionary techniques in secondary steel making process is yet to be done. In this work, data driven multi‐objective optimization is implemented to lower the phosphorous content in the steel bath after completion of secondary steel making process by using minimum lime. The input variables considered for this investigation are process route, minimum vacuum level, process time, ladle inlet temperature, ladle outlet temperature, SSM carbon input, SSM manganese input, SSM phosphorus input, SSM sulfur input, SSM silicon input, Al addition, and tundish sulfur. A data driven Evolutionary Neural Network (EvoNN) algorithm is used to form the meta‐models by training of a dataset consisting of 76 data entries obtained from a steel plant. Analysis of Pareto front gives an effective and beneficial guideline so that one can achieve low tundish phosphorous content avoiding higher amount of slag generation due to extra lime addition during secondary steel making process. This work helps to select the optimum secondary steel making process route for producing LPG grade steel depending upon composition of liquid steel input to secondary steel making units. [ABSTRACT FROM AUTHOR]

Coherent ptychographic imaging experiments often discard the majority of the flux from a light source to define the coherence of the illumination. Even when the coherent flux is sufficient, the stability required during an exposure is another important limiting factor. Partial coherence analysis can considerably reduce these limitations. A partially coherent illumination can often be written as the superposition of a single coherent illumination convolved with a separable translational kernel. This article proposes the gradient decomposition of the probe (GDP), a model that exploits translational kernel separability, coupling the variances of the kernel with the transverse coherence. An efficient first‐order splitting algorithm (GDP‐ADMM) for solving the proposed nonlinear optimization problem is described. Numerical experiments demonstrate the effectiveness of the proposed method with Gaussian and binary kernel functions in fly‐scan measurements. Remarkably, GDP‐ADMM using nanoprobes produces satisfactory results even when the ratio between the kernel width and the beam size is more than one, or when the distance between successive acquisitions is twice as large as the beam width. [ABSTRACT FROM AUTHOR]

The effect of MgO and low TiO2 content on the solidification of CaO–SiO2–Al2O3 based mold fluxes is investigated. The crystallization and viscosity behaviors are analyzed using single hot thermocouple technique (SHTT) and rotating viscometer, respectively. Continuous‐cooling‐transformation (CCT) results point to an increase of critical cooling rate (CCR) with increasing MgO content. Conversely, the presence of TiO2 seems to mitigate the effect of MgO on the crystallization due to the strong glass former characteristic of titanium dioxide. Viscosity measurements show an increase with increasing MgO content in slags containing TiO2. Break temperatures (Tbr) are compared to the onset crystallization temperatures from CCT experiments. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) analysis results indicate the presence of melilite (Al2Ca2Mg0.5O7Si1.5) for all samples of mold flux containing both MgO and TiO2. [ABSTRACT FROM AUTHOR]

Fluorine-free mold flux has received ever increasing attentions due to environmental problems cause by fluorine in casting. Fluorine-free mold fluxes based on CaO-Al2O3-B2O3 systems are developed in the present work. The melting temperatures, viscosities, and crystallization behaviors of CaO-Al2O3-B2O3 based mold fluxes are investigated. The results show that the melting temperatures decrease with the increasing B2O3 and Na2O content, while the melting temperatures of mold fluxes first increase with increasing CaO/Al2O3 mass ratios, and then decrease with further increasing CaO/Al2O3 ratios. The viscosity values of mold fluxes decrease with increasing of B2O3, Na2O content, and CaO/Al2O3 ratio. The crystallization temperatures of mold fluxes decrease with the increasing B2O3 and Na2O, while the crystallization temperature of mold fluxes first increases with increasing CaO/Al2O3 mass ratios, and then decreases with further increasing CaO/Al2O3 ratios. XRD and SEM are used to analyze the sequence of crystallization. Ca3Al2O6 crystals are precipitated at first, followed by LiAlO2 during continuous cooling for all samples, and Ca3B2O6 is precipitated finally. It is shown that CaO-Al2O3-B2O3 based mold flux has a potential to be applied as a kind of F-free mold flux. [ABSTRACT FROM AUTHOR]

Pump-and-treat (P&T) is a widely applied remedy for groundwater remediation at many types of sites for multiple types of contaminants. Decisions regarding major changes in the remediation approach are an important element of environmental remediation management for a site using P&T. While existing guidance documents provide information on design, operation, and optimization for P&T systems, these documents do not provide specific technical guidance to support remedy decisions regarding when to transition to a new remedy or to initiate closure of the P&T remedy. A structured approach for P&T performance assessment was developed and is described herein, using analysis of three example P&T systems. These examples highlight key aspects of the performance assessment decision logic and represent assessment outcomes associated with optimizing the P&T system, transitioning from P&T to natural attenuation, and supplementing P&T with another technology to hasten transition to natural attenuation. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the optimal chemical composition of the tundish flux, which can efficiently absorb macro and micro inclusions from 16MnCrS5 case hardening steel. Computation of phase diagram is used as an approach to understand properties and behavior of tundish slags in casting conditions. Thermodynamic computation of steel − slag reactions is performed to find out the capability of different tundish slags to absorb inclusions. Industrial trials are, then, carried out with the slags to verify their functionality, when casting several heats in sequence. Results show that by tailoring tundish slag composition the steel cleanliness can be improved. Basic Ca-Mg-aluminate type slags have potential for wide use, as they can be easily adjusted chemically stable against the steel and have ability to absorb inclusions. The slag optimization is, however, a complex issue depending for example on the steel grade. [ABSTRACT FROM AUTHOR]

We use cryogenic ion vibrational spectroscopy to characterize the structure and fluxionality of the magic number boron cluster B13+. The infrared photodissociation (IRPD) spectrum of the D2-tagged all-11B isotopologue of B13+ is reported in the spectral range from 435 to 1790 cm−1 and unambiguously assigned to a planar boron double wheel structure based on a comparison to simulated IR spectra of low energy isomers from density-functional-theory (DFT) computations. Born-Oppenheimer DFT molecular dynamics simulations show that B13+ exhibits internal quasi-rotation already at 100 K. Vibrational spectra derived from these simulations allow extracting the first spectroscopic evidence from the IRPD spectrum for the exceptional fluxionality of B13+. [ABSTRACT FROM AUTHOR]

The drag due to resolved and subgrid flow blocking and gravity waves is examined in simulations of flow over mountainous islands at 'grey zone' resolutions, in which the processes are neither well resolved or fully subgrid-scale. Simulations of flows over narrow (South Georgia) and broad (New Zealand) mountain barriers are used to determine the behaviour of resolved and parametrized pressure drag and gravity-wave momentum fluxes as a function of horizontal grid length. Analysis of the pressure drag in spectral space suggests that contributions from wavelengths shorter than 8-10 grid lengths are poorly resolved and that parametrization schemes should compensate for the missing drag from processes on these scales, rather than strictly the subgrid scales. The model performance for South Georgia is such that the total (resolved plus parametrized) pressure drag is approximately invariant across a range of resolutions. The parametrized (resolved) drag increases (decreases) as the grid length increases and the resolved and parametrized drag become comparable when the characteristic island wavelength is approximately 8 times the grid length. This is not true when the same tuning of the drag parametrization is applied to New Zealand, in which case the parametrized drag increases too rapidly with increasing grid length. However, satisfactory results are obtained when the scheme is re-tuned and it is shown that the optimal tuning for the two islands is consistent with scaling the subgrid orographic heights to be representative of the orography on longer length-scales, of up to 10 grid lengths. The results suggest that drag schemes require orographic information on these longer scales, rather than only the subgrid scale. At the coarsest resolutions, where the island wavelength and grid length are similar, the parametrized drag is too small because the grid boxes are increasingly treated as sea points. Possible solutions to this problem are discussed. [ABSTRACT FROM AUTHOR]

When continuously casting high Al steels, CaO-SiO2 based mold fluxes can be easier for sequence casting, but due to the significant reactions of the Al in the metal with SiO2, slab surface quality is not desirable. When increasing basicity of CaO-SiO2 based mold fluxes, slab surface quality can be improved, but thick slag rim can easily be formed during cooling process. Therefore, non-isothermal crystallization kinetics of mold fluxes used for high Al steels are studied to optimize the crystallization behavior of "working" fluxes. Results indicate that the addition of Li2O can decrease crystallization temperature and crystallization rate within the range of Na2O studied. The Avrami exponent determined by Avrami equation indicates that disk-like growth type and spherulitic-like growth type are the main mechanisms in crystallization, which is consistent with results observed under SEM. When mold flux contains 8% Na2O and 4.5% Li2O, the effective activation energy is between -299 and -488 KJ mol-1. When mold flux contains no Na2O and 6.5% Li2O, the effective activation energy is between -266 and -414 KJ mol-1, which indicates that Na2O-free mold fluxes containing high Li2O is beneficial for improving crystallization characteristics and realizing sufficient lubrication. [ABSTRACT FROM AUTHOR]

During the refining of 28CrMo47 drill pipe steel, it is found that the product often has internal defects and cracks. The present work is initiated with a view to examine if these problems could be solved by optimizing the slag chemistry of the refining slag. Three series of slags, namely, slag A (57.09%CaO-15.74%SiO2-16.35%Al2O3-5.35%MgO, original slag in the steel plant), slag B (55%CaO-21%SiO2-12%Al2O3-7%MgO-5%CaF2), and slag C (51%CaO-17%SiO2-25%Al2O3-7%MgO) are designed and their viscosities are measured. The effect of Al2O3 content on viscosity of the slag C is also investigated as part of the slag optimization. Slag-steel equilibrium experiments are subsequently carried out in order to understand the effect of the slag chemistry, especially the variation in the Al2O3 content in the same on the inclusions in drill pipe steel. It is concluded that both increasing Al2O3 content of the slag used in the refining unit in the plant and addition of CaF2 could decrease effectively the slag viscosity. Inclusions in steel equilibrated with slag C1, corresponding to 51%CaO-7%MgO-25%Al2O3-17SiO2, consisted mainly of low melting point CaO-Al2O3 complex, which did not have any negative effect on the steel quality. [ABSTRACT FROM AUTHOR]

A table of content for the issue is presented which includes studies on effect of the carbon content on the potency of the intragranular ferrite (IGF) formation, multiphase flux and production, detection, and identification of Non-Metallic Inclusions (NMI).

Solid solutions KTi1-XHfXOPO4 (х = 0.008 - 0.107) possessing the KTiOPO4 structure, have been synthesized in molten system K2O-P2O5-TiO2-HfF4. The crystal growth experiment of Hf-doped KTP crystal has been reported. The X-ray powder diffraction data and chemical analysis are also presented. It has been shown that KTiOPO4 crystal structure slightly changes when Hf incorporates into the framework. Transmission/absorption spectra of KTi0.974Hf0.026OPO4 crystals have been recorded. The incorporation of Hf ions shifts the optical absorption edge in the UV-visible spectrum towards the long-wavelength region with absorption near 387 nm. [ABSTRACT FROM AUTHOR]

We present an analytic and numerical analysis of several properties of a composite material with stiff imperfect interface conditions. Spaces of functions are identified wherewe can guarantee existence and uniqueness of solutions. In particular, formulas for the temperature distribution and flux are exhibited. Numerical calculations of the material characteristics such as temperature, flux and the effective conductivity are also performed and interpreted. [ABSTRACT FROM AUTHOR]

In this study, crystallization behavior of an industrial mold flux was investigated using both single hot thermocouple technique (SHTT) and double hot thermocouple technique (DHTT). Continuous cooling transformation (CCT) and time-temperature transformation (TTT) diagrams were constructed using SHTT. The critical cooling rate in continuous cooling process was determined as 7 °C s−1 above which a glassy phase was formed. The TTT diagram showed two noses at approximately 1000 and 1075 °C. Phase identification carried out using X-ray diffraction (XRD) revealed that dicalcium silicate (Ca2SiO4) was the major phase at both 950 and 1100 °C, together with minor precipitates of Na2CaSi3O8 and Ca2MgSi2O7 whose concentrations were relatively higher at 950 °C. Cuspidine (Ca4Si2O7F2) was also identified by XRD at 950 °C. Crystallization kinetics was analyzed using Johnson-Mehl-Avrami-Kolmogorov equation. DHTT was used to simulate the temperature gradient between copper mold and strand in the continuous casting mold. Glassy phase was formed quickly near the cold side when it was quenched from 1500 to 800 °C. Crystals started to precipitate in the glassy region after 48 s. Then major part of the glassy region was gradually transformed to crystalline phase and the crystals subsequently grew to the liquid region. A steady three-layer state was reached after 360 s. [ABSTRACT FROM AUTHOR]

This paper investigated melting properties and viscosity of SiO2-CaO-Al2O3-B2O3 fluxes with a mass ratio of CaO/SiO2 from 0.83 to 1.5 and B2O3 content from 5 to 9 wt%. Melting properties of these fluxes were studied using the hot stage microscopy method; viscosity was measured using the rotating cylinder method. Break temperature was also determined from the viscosity change with temperature in flux cooling process. Equilibrium liquidus temperature was calculated using FactSage. Increase in CaO/SiO2 ratio was found to decrease hemispherical temperature and viscosity. The addition of B2O3 did not significantly affect hemispherical temperature but decreased the flux viscosity. Viscosity was analyzed in relation to the flux structure. The increase of the CaO/SiO2 ratio reduced the degree of flux polymerization, and B2O3 apparently acted as a weak network modifier under the low concentration of B2O3. The experimental viscosity was in a good agreement with calculated viscosity using the modified NPL model. [ABSTRACT FROM AUTHOR]

Development of fluoride-free mould flux is important for steel continuous casting. Properties of the mould flux depend on the flux crystallinity. This paper analyzes phase composition of fluxes containing B2O3, TiO2, Na2O, and MgO which can be feasible candidates to replace the fluorides. The phase equilibria of these fluoride-free boracic mould fluxes were calculated using the thermochemical software FACTSage. In the process of crystallization of the CaOSiO2Al2O3B2O3Na2O flux with high CaO/SiO2, combeite (Na2,Ca)Na2CaSi3O9, Ca11B2Si4O22, and nepheline NaAlSiO4 were formed, which can substitute cuspidine in the fluoride-containing fluxes. At high CaO/SiO2, adding MgO into CaOSiO2Al2O3B2O3Na2OTiO2 mould flux remarkably increased crystallization temperature by forming merwinite (Ca3MgSi2O8), decreasing the relative crystal phase contents of (Na2,Ca)Na2CaSi3O9 and Ca11B2Si4O22. The calculated data were in reasonable agreement with results of XRD and SEM/EDS analyses of selected boracic fluxes. [ABSTRACT FROM AUTHOR]

The formation of the toxic and bioaccumulating monomethylmercury (MMHg) in marine systems is poorly understood, due in part to sparse data from many ocean regions. We present dissolved mercury (Hg) speciation data from 10 stations in the North and South Equatorial Pacific spanning large water mass differences and gradients in oxygen utilization. We also compare the mercury content in suspended particles from six stations and sinking particles from three stations to constrain local Hg sources and sinks. Concentrations of total Hg (THg) and methylated Hg in the surface and intermediate waters of the Equatorial and South Pacific suggest Hg cycling distinct from that of the North Pacific gyre. Maximum concentrations of 180 fM for both MMHg and dimethylmercury (DMHg) are observed in the Equatorial Pacific. South of the equator, concentrations of MMHg and DMHg are less than 100 fM. Sinking fluxes of particulate THg can reasonably explain the shape of dissolved THg profiles, but those of MMHg are too low to account for dissolved MMHg profiles. However, methylated Hg species are lower than predicted from remineralization rates based on North Pacific data, consistent with limitation of methylation in Equatorial and South Pacific waters. Full water column depth profiles were also measured for the first time in these regions. Concentrations of THg are elevated in deep waters of the North Pacific, compared to those in the intermediate and surface waters, and taper off in the South Pacific. Comparisons with previous measurements from nearby regions suggest little enrichment of THg or MMHg over the past 20 years. [ABSTRACT FROM AUTHOR]

Literature data on benthic dissolved iron (DFe) fluxes (µmol m−2 d−1), bottom water oxygen concentrations (O2BW, μM), and sedimentary carbon oxidation rates (COX, mmol m−2 d−1) from water depths ranging from 80 to 3700 m were assembled. The data were analyzed with a diagenetic iron model to derive an empirical function for predicting benthic DFe fluxes: [ABSTRACT FROM AUTHOR]

The importance of terrestrial and aquatic ecosystems in controlling nitrogen dynamics in streams is a key interest of ecologists studying dissolved inorganic nitrogen (DIN) export from watersheds. In this study, we coupled a stream model with a terrestrial ecohydrological model and conducted a global sensitivity analysis to evaluate the relative importance of both ecosystems to nitrogen export. We constructed two scenarios ('normal' and high nitrate loads) to explore conditions under which terrestrial (lateral nitrate flux) or aquatic ecosystems (instream nutrient processes) may be more important in controlling DIN export. In a forest catchment, although the forest ecosystem controls the nitrogen load to streams, sensitivity results suggested that most nitrogen output from the terrestrial ecosystem was taken up by instream microbial immobilization associated with benthic detritus and retained in detritus. Later the immobilized nitrogen was remineralized as DIN. Therefore, the intra-annual pattern of DIN concentration in the stream was low in fall and became high in spring. Not only was instream microbial immobilization saturated with the high nitrogen load scenario, but also the net effect of immobilization and mineralization on DIN export was minimized because nitrogen cycling between organic and inorganic forms was accelerated. Overall, our linked terrestrial-aquatic model simulations demonstrated that stream process could significantly affect the amount and timing of watershed nitrogen export when nitrogen export from the terrestrial system is low. However, when nitrogen export from the terrestrial system is high, the effect of stream processes is minimal. [ABSTRACT FROM AUTHOR]

Due to its high content in Al-TRIP steel, Al is easily to react with SiO2 in mould fluxes during the continuous casting process, which results in the drastic decrease of SiO2 content, increase of Al2O3 content and the basicity (R = CaO/SiO2), respectively. The magnitude change of physical properties of the slag can affect continuous casting process and the surface quality of slabs. Especially, the change of basicity influenced the crystallization property, and thus influenced the heat transfer of mould fluxes. In this study, three CaO-SiO2 based mould fluxes A, B, and C with different basicity (A was the originally used mould fluxes, B and C were the newly developed mould fluxes) were used to cast high aluminum TRIP steel with 0.80-1.00% Al and 0.085-0.115% carbon. The property change of mould fluxes and its influence on the quality of the slab surface were evaluated. It is indicated that appropriate increase of the basicity of base mould fluxes was beneficial to improve the crystallization property of spent slag and for the inhibition of heat transfer so as to reduce the occurrence of cracking and depression on the slab surface effectively. And also, it can shorten the time of slag-metal reaction reaching dynamic equilibrium and the length of transition slab with defect on surface in the start casting stage. Accordingly, the quality of slab cast by mould fluxes C was the best. [ABSTRACT FROM AUTHOR]

ABSTRACT Carbide slag is a kind of industrial waste obtained in the production of acetylene that is the raw material of polyvinyl chloride in chlor-alkali plants. The carbide slag modified by pyroligneous acid was proposed as a CO2 sorbent at high temperature. The CO2 capture capacity of the carbide slag modified by pyroligneous acid in the calcium looping cycles was investigated in a thermogravimetric analyzer and a dual fixed-bed reactor. The modified carbide slag exhibits better CO2 capture capacity than the carbide slag. The modified carbide slag releases the organic substances whose combustion leads to a drop in CO2 capture capacity. The pre-calcination treatment of the modified carbide slag at 400 °C before the first calcination was employed to avoid the combustion of the organic substances. The pre-calcined modified carbide slag exhibits higher carbonation conversions, compared with the modified carbide slag without pre-calcination treatment. The pre-calcined modified carbide slag achieves higher carbonation conversions at 950 °C and shows larger surface area and pore volume than the modified carbide slag in the cycles. It indicates that combining the modification by pyroligneous acid with the pre-calcination treatment apparently improves cyclic CO2 capture capacity of the carbide slag in the multiple cycles. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new experimental apparatus for simulating mold oscillation of continuous casting was developed to clarify the flux lubrication mechanism in mold channel. Mixed oil which was simulated mold flux was poured and infiltrated down into the channel, and the consumption, liquid level and pressure of mixed oil were detected in the process of oscillation as well as the mechanism of flux process. The results show that the channel of flux with a profile becomes wider along the casting direction, and the lag time of periodical shifting pressure to the oscillating motion is strongly dependent on the flux viscosity and oscillation frequency. The liquid film thickness of flux has a significant influence on the infiltration behavior compared with the oscillating motion of the mold. The liquid flux infiltrates down from the end of positive strip time to the beginning of next positive strip time, and the infiltration is largely dependent on the negative strip time in between. The increase of viscosity of flux, casting speed and oscillation frequency enhances the liquid friction due to the reduction of the mold flux consumption. On the contrary, the higher non-sinusoidal oscillation factor improves the infiltration and decreases the frictional force. The oscillation amplitude increases the consumption and liquid friction slightly. [ABSTRACT FROM AUTHOR]

Seepage flux from ephemeral streams can be an important component of the water balance in arid and semiarid regions. An emerging technique for quantifying this flux involves the measurement and simulation of a flood wave as it moves along an initially dry channel. This study investigates the usefulness of including surface water and groundwater data to improve model calibration when using this technique. We trialed this approach using a controlled flow event along a 1387 m reach of artificial stream channel. Observations were then simulated using a numerical model that combines the diffusion-wave approximation of the Saint-Vénant equations for streamflow routing, with Philip's infiltration equation and the groundwater flow equation. Model estimates of seepage flux for the upstream segments of the study reach, where streambed hydraulic conductivities were approximately 101 m d−1, were on the order of 10−4 m3 d−1 m−2. In the downstream segments, streambed hydraulic conductivities were generally much lower but highly variable (∼10−3 to 10−7 m d−1). A Latin Hypercube Monte Carlo sensitivity analysis showed that the flood front timing, surface water stage, groundwater heads, and the predicted streamflow seepage were most influenced by specific yield. Furthermore, inclusion of groundwater data resulted in a higher estimate of total seepage estimates than if the flood front timing were used alone. [ABSTRACT FROM AUTHOR]

Boreal rivers and streams are known as hot spots of CO2 emissions, yet their contribution to CH4 emissions has traditionally been assumed to be negligible, due to the spatially fragmented data and lack of regional studies addressing both gases simultaneously. Here we explore the regional patterns in river CO2 and CH4 concentrations ( pCO2 and pCH4), gas exchange coefficient ( k), and the resulting emissions in a lowland boreal region of Northern Québec. Rivers and streams were systematically supersaturated in both gases, with both pCO2 and pCH4 declining along the river continuum. The k was on average low and increased with stream order, consistent with the hydrology of this flat landscape. The smallest streams (order 1), which represent < 20% of the total river surface, contributed over 35% of the total fluvial greenhouse gas (GHG) emissions. The end of winter and the spring thaw periods, which are rarely included in annual emission budgets, contributed on average 21% of the annual GHG emissions. As a whole, the fluvial network acted as significant source of both CO2 and CH4, releasing on average 1.5 tons of C (CO2 eq) yr−1 km−2 of landscape, of which CH4 emissions contributed approximately 34%. We estimate that fluvial CH4 emissions represent 41% of the regional aquatic (lakes, reservoirs, and rivers) CH4 emissions, despite the relatively small riverine surface (4.3% of the total aquatic surface). We conclude that these fluvial networks in boreal lowlands play a disproportionately large role as hot spots for CO2 and more unexpectedly for CH4 emissions. [ABSTRACT FROM AUTHOR]

Terrestrial biosphere models can help identify physical processes that control carbon dynamics, including land-atmosphere CO2 fluxes, and have great potential to predict the terrestrial ecosystem response to changing climate. The skill of models that provide continental-scale carbon flux estimates, however, remains largely untested. This paper evaluates the performance of continental-scale flux estimates from 17 models against observations from 36 North American flux towers. Fluxes extracted from regional model simulations were compared with co-located flux tower observations at monthly and annual time increments. Site-level model simulations were used to help interpret sources of the mismatch between the regional simulations and site-based observations. On average, the regional model runs overestimated the annual gross primary productivity (5%) and total respiration (15%), and they significantly underestimated the annual net carbon uptake (64%) during the time period 2000-2005. Comparison with site-level simulations implicated choices specific to regional model simulations as contributors to the gross flux biases, but not the net carbon uptake bias. The models performed the best at simulating carbon exchange at deciduous broadleaf sites, likely because a number of models used prescribed phenology to simulate seasonal fluxes. The models did not perform as well for crop, grass, and evergreen sites. The regional models matched the observations most closely in terms of seasonal correlation and seasonal magnitude of variation, but they have very little skill at interannual correlation and minimal skill at interannual magnitude of variability. The comparison of site vs. regional-level model runs demonstrated that (1) the interannual correlation is higher for site-level model runs, but the skill remains low; and (2) the underestimation of year-to-year variability for all fluxes is an inherent weakness of the models. The best-performing regional models that did not use flux tower calibration were CLM-CN, CASA-GFEDv2, and SIB3.1. Two flux tower calibrated, empirical models, EC-MOD and MOD17+, performed as well as the best process-based models. This suggests that (1) empirical, calibrated models can perform as well as complex, process-based models and (2) combining process-based model structure with relevant constraining data could significantly improve model performance. [ABSTRACT FROM AUTHOR]

ABSTRACT In the framework of the Orowan model, a theoretical approach is developed to explain the appearance of a break (local minimum and maximum) on a curve of creep rate dependence on temperature of materials under irradiation. The break is explained by competition of radiation and thermal defect fluxes to dislocations. At some temperature, the fluxes of interstitial atoms and vacancies become equal and compensate each other. Thus, the dislocations do not climb. Climb-glide mechanism does not contribute to the creep and the creep decreases. It is shown that the presence of sinks with different preference coefficients is necessary for the appearance of the break. Theoretical and experimental results are in good agreement. [ABSTRACT FROM AUTHOR]

Although 2-methylchromones react with cyanoacetamide and N-methyl cyanoacetamide in the presence of sodium ethoxide in refluxing ethanol to produce 6-(2-hydroxyaryl)-4-methyl-2-oxo-1,2-dihydropyridine-3-carbonitriles, their reactions with ethyl cyanoacetate under the same conditions took an entirely different course and gave 7-hydroxy-6-imino-9-methyl-6 H-benzo[ c]chromene-8-carbonitriles. [ABSTRACT FROM AUTHOR]

Viscosities of B2O3 and TiO2-bearing fluoride-free mold fluxes have been measured by the rotating cylinder method in this work. Effects of different B2O3, TiO2 content, and basicities on the viscosity characteristics have been examined. Viscosity of fluoride-free mold fluxes containing B2O3 and TiO2 was found to decrease with the increase of B2O3, TiO2 content, and basicity. The values of apparent activation energy for viscous flow of slags decrease with additions of B2O3 and TiO2 and the increase of basicity. Two parameters A and B in Riboud model were re-evaluated based on the present experimental data, and the modified Riboud model was used to estimate the viscosity of fluoride-free slag system investigated in present work. The viscosity values obtained by the experimental measurement were in good agreement with those calculated by the modified Riboud model. [ABSTRACT FROM AUTHOR]

Viscosities of B2O3 and TiO2-bearing fluoride-free mold fluxes have been measured by the rotating cylinder method in this work. Effects of different B2O3, TiO2 content, and basicities on the viscosity characteristics have been examined. Viscosity of fluoride-free mold fluxes containing B2O3 and TiO2 was found to decrease with the increase of B2O3, TiO2 content, and basicity. The values of apparent activation energy for viscous flow of slags decrease with additions of B2O3 and TiO2 and the increase of basicity. Two parameters A and B in Riboud model were re-evaluated based on the present experimental data, and the modified Riboud model was used to estimate the viscosity of fluoride-free slag system investigated in present work. The viscosity values obtained by the experimental measurement were in good agreement with those calculated by the modified Riboud model. [ABSTRACT FROM AUTHOR]

Stirring effects and impacting characteristics of conventional and various swirl-type oxygen lances (Swirl angles are 5°, 10°, and 13°, respectively) on the molten pool were studied. The mixing time, impacting depth and impacting diameter were measured by water model experiment. The flow field characteristics of gas-liquid two phase flow were simulated using Fluent software. It is found that 10° swirl-type oxygen lance injection can get the shortest mixing time which is only 47.6 s. The area surrounded by isovelocity is larger in molten pool when injecting by the swirl-type oxygen lance. When injecting by the 10° swirl-type oxygen lance, the area is the largest and the flow velocity of liquid steel is the highest. On this basis, the 10° swirl-type oxygen lance was experimented in 150 t vanadium extraction converter. The experiment shows that the swirl-type oxygen lance can guarantee the normal smelting process. Compared with the conventional oxygen lance, the reduction ratio of vanadium content in semi-steel is 17.8%, vanadium extraction rate is increased by 5.1%, V2O5 grade of vanadium slag is increased by 0.93% and iron loss is reduced. It provides a new technology to improve the recovery of vanadium resources in converter. [ABSTRACT FROM AUTHOR]

Atmospheric deposition is one of the major sources of nutrients bringing trace metals to remote marine biota. In this study, total atmospheric deposition and crustal aerosol concentrations were monitored at Kerguelen Islands (49°18'S; 70°07'E) in the Southern Ocean during a short campaign in early 2005 and then continuously for about 2 years (2009-2010). Results show very low levels of atmospheric dust and trace metals concentrations but higher deposition fluxes man expected. The averaged total dust deposition flux as derived from Al deposition measurements is 659 μg m-2 d-1. Simultaneously measured Fe and Co deposition fluxes are respectively 29 μ m-2 d-1 (520 nmol m-2 d-1) and 0.014 μ m-2 d-1 (0.24 nmol m-2 d-1), giving typically crustal elemental ratios to Al of 0.54 and 2.6 10-4. Measured dust deposition is in relatively good agreement with those simulated by current atmospheric models, but suggest that previous indirect calculations from field experiments are too low by a factor of 20. Observations and model results show that dust is transported above the marine atmospheric boundary layer to Kerguelen Islands, and thus that surface concentrations are not representative of the total dust column. Indeed, using surface concentrations leads to very large computed wet scavenging ratios, and to the conclusion that it is not appropriate to derive deposition fluxes from surface concentrations at remote ocean sites. [ABSTRACT FROM AUTHOR]

The dedicated small-molecule single-crystal X-ray diffraction beamline (I19) at Diamond Light Source has been operational and supporting users for over three years. I19 is a high-flux tunable-wavelength beamline and its key details are described in this article. Much of the work performed on the beamline involves structure determination from small and weakly diffracting crystals. Other experiments that have been supported to date include structural studies at high pressure, studies of metastable species, variable-temperature crystallography, studies involving gas exchange in porous materials and structural characterizations that require analysis of the diffuse scattering between Bragg reflections. A range of sample environments to facilitate crystallographic studies under non-ambient conditions are available as well as a number of options for automation. An indication of the scope of the science carried out on the beamline is provided by the range of highlights selected for this paper. [ABSTRACT FROM AUTHOR]

Deoxidation during electroslag remelting of S136 die steel was experimentally studied. The characteristics of inclusions in the electrode and ESR ingots were determined by image analyzer and SEM-EDS. The results show that the oxygen content can be reduced from 89 ppm in the electrode to the lowest (12 ppm) in the ingot only when protective Ar gas remelting in combination with specially designed slag deoxidation treatment were employed simultaneously. The proportion of the oxygen combined as oxide inclusions increases with decreasing the total oxygen content in ESR ingot. The original inclusions in the electrode are mainly large (Mn,Cr)S and the large inclusions in the form of Al2O3 core surrounded by an outer sulfide layer, besides a few pure Al2O3 inclusions. After ESR process, while only pure Al2O3 inclusions with the size of about 1 µm were observed in ESR ingots. The large inclusions in the electrode were removed during ESR process. With higher oxygen content in the ingot, the contents of inclusions and large inclusions would be relatively higher. The results from industrial experiments have confirmed the availability of the present oxygen control technique. The mechanisms of oxygen behavior and control as well as inclusion evolution during ESR process were proposed based on experimental results along with thermodynamic analysis. [ABSTRACT FROM AUTHOR]

Coastal rivers represent a significant pathway for the delivery of natural and anthropogenic sediment-associated chemical constituents to the Atlantic, Pacific and Gulf of Mexico coasts of the conterminous USA. This study entails an accounting segment using published average annual suspended sediment fluxes with published sediment-associated chemical constituent concentrations for (1) baseline, (2) land-use distributions, (3) population density, and (4) worldwide means to estimate concentrations/annual fluxes for trace/major elements and total phosphorus, total organic and inorganic carbon, total nitrogen, and sulphur, for 131 coastal river basins. In addition, it entails a sampling and subsequent chemical analysis segment that provides a level of 'ground truth' for the calculated values, as well as generating baselines for sediment-associated concentrations/fluxes against which future changes can be evaluated. Currently, between 260 and 270 Mt of suspended sediment are discharged annually from the conterminous USA; about 69% is discharged from Gulf rivers ( n = 36), about 24% from Pacific rivers ( n = 42), and about 7% from Atlantic rivers ( n = 54). Elevated sediment-associated chemical concentrations relative to baseline levels occur in the reverse order of sediment discharges: Atlantic rivers (49%) > Pacific rivers (40%) > Gulf rivers (23%). Elevated trace element concentrations (e.g. Cu, Hg, Pb, Zn) frequently occur in association with present/former industrial areas and/or urban centres, particularly along the northeast Atlantic coast. Elevated carbon and nutrient concentrations occur along both the Atlantic and Gulf coasts but are dominated by rivers in the urban northeast and by southeastern and Gulf coast (Florida) 'blackwater' streams. Elevated Ca, Mg, K, and Na distributions tend to reflect local petrology, whereas elevated Ti, S, Fe, and Al concentrations are ubiquitous, possibly because they have substantial natural as well as anthropogenic sources. Almost all the elevated sediment-associated chemical concentrations found in conterminous US coastal rivers are lower than worldwide averages. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A thermodynamic model for calculating the mass action concentrations of structural units in CaO-SiO2-MgO-FeO-MnO-Al2O3-CaF2 slags, i.e., the IMCT- N i model, has been developed based on the ion and molecule coexistence theory (IMCT). The calculated comprehensive mass action concentration of iron oxides $N_{{\rm Fe}_{t} {\rm O}} $ has been compared with the reported activity of iron oxide $a_{{\rm Fe}_{t} {\rm O}} $ in 14 FeO-containing slag systems from literatures. The good agreement between the calculated $N_{{\rm Fe}_{t} {\rm O}} $ and reported $a_{{\rm Fe}_{t} {\rm O}} $ indicates that the developed IMCT- N i model can be successfully applied to predict the activity of iron oxide $a_{{\rm Fe}_{t} {\rm O}} $ as well as the slag oxidation ability of CaO-FeO (s1), SiO2-FeO (s2), CaO-SiO2-FeO (s3), CaO-FeO-Al2O3 (s4), SiO2-MgO-FeO (s5), SiO2-FeO-Al2O3 (s6), CaO-SiO2-FeO-Al2O3 (s7), CaO-SiO2-MgO-FeO-Al2O3 (s8), SiO2-FeO-MnO (s9), SiO2-FeO-MnO-Al2O3 (s10), FeO-MnO (s11), FeO-MnO-Al2O3 (s12), CaO-FeO-CaF2 (s13), and CaO-SiO2-FeO-CaF2 slags (s14) in a temperature range of 1473-1973 K. [ABSTRACT FROM AUTHOR]

The applicability of rotating rod technique in the study of lime dissolution in slag was investigated. Both computational fluid dynamic (CFD) and cold model experiments showed that the mass transfer due to radial velocity introduced by forced convection was zero if the rod was long. The mass transfer by forced convection was also less important in comparison with natural convection and diffusion when the rod was half length of the height of the bath. This finding was in accordance with the criteria put forward by the original work that the method could only be applicable when a thin disk (instead of rod) with big diameter and big liquid bath were used. To study the lime dissolution by forced convection a new experimental technique was developed. A cube was placed in the slag that was eccentrically stirred. The whole system, viz. the sample along with the slag could be quenched. The new technique could study the effect of forced convection on the dissolution. The microscopic study on the quenched slag-lime samples could reveal the dissolution mechanism successfully. [ABSTRACT FROM AUTHOR]

The presence and flux of biogenic methane-rich free phase gas that is eventually released to the atmosphere influence water content (9) of peat soils below the water table. Small variations in gas content in peat soils at near-saturation 9 could be inferred by changes in dielectric permittivity. but detailed measurements in that range of 8 needed to develop calibration functions are lacking. Our experiment uses a new method for varying 0 in the sample using elevated pressure to reduce the naturally occurring volumetric gas content in a manner similar to what occurs in situ under atmospheric pressure change. which relevant to understanding carbon gas cycling in peatlands. We recorded dielectric permittivity using a 1.6 MHz ground-penetrating radar antenna at multiple water contents between 0.87 and 0.95 rn~ m3 on four peat monoliths with varying levels of humification and with <5% gas content as is commonly observed in the field. We identified empirical equations that were linear over the range of 0 investigated and optimized a dielectric mixing model for estimating 0 from GPR. These results indicate that there are differences in the permittivity-9 relationships developed between peat samples and suggest that variability in dielectric relationships may be attributed to peat structure and particle orientation. The empirical relationships developed in this study confirm the utility of previously applied multiphase mixing models for estimating peat properties using methods sensitive to dielectric permittivity. This work is relevant to studies of gas content in peat and the role of peatlands in the carbon cycle. [ABSTRACT FROM AUTHOR]

The low-temperature sintering behavior of Pb(Zr0.53, Ti0.47)O3-Sr(K0.25, Nb0.75)O3 (PZT-SKN) piezoelectric ceramics with LiBiO2 and CuO addition has been investigated. The addition of 6 wt% LiBiO2 or 1 wt% LiBiO2+1 wt% CuO promotes the sinterability of 0.98PZT-0.02SKN ceramics owing to the generation of a liquid phase, resulting in a reduction of sintering temperature by about 300°-350°C. The microstructure, dielectric, and piezoelectric properties of flux-sintered ceramics were examined and compared with materials conventionally sintered at 1250°C. PZT-SKN ceramics with 1 wt% LiBiO2+1 wt% CuO addition were sintered to high density at 900°C for 1 h. The resulting samples exhibited a high-field d33 piezoelectric coefficient of 415 pm/V with a Curie temperature Tc of around 351°C, dielectric constant ɛr of 1235, and planar coupling factor kp of 0.54. The reduced sintering temperature and short soaking time, together with the favorable dielectric and piezoelectric properties of the fluxed PZT-SKN ceramics, demonstrate the potential opportunity of integration with low-temperature cofired ceramic materials and low-fire electrode materials for the multilayer piezoelectric transducer application. [ABSTRACT FROM AUTHOR]

This paper compares data on N fluxes compiled by Schulze and colleagues, with information available in the literature and publicly available open databases, and finds important discrepancies for a number of such fluxes for Europe (emissions, deposition, aerosol formation of compounds containing N) - exceeding a factor of two in several cases. A qualitative assessment of the uncertainties of the respective approaches indicates that these differences are beyond the uncertainty margins that can be reasonably attributed to the respective data.We conclude that the results should be used with caution, that agricultural application of N should still be considered to be the largest source of N released to the environment, and that this agricultural N affects soils more strongly than atmospheric deposition, at the European scale. [ABSTRACT FROM AUTHOR]

Ladle slag is an internal by-product generated within the steelmaking industry during the refining of steel. The realisation of beneficial inherent properties of ladle slag as a binder supplement or substitute material is believed to be advantageous with respect to both economy and environment for steelmakers. For this reason, the current study has focused on highlighting the properties of ladle slag that are pertinent to the formation of calcium aluminate hydrates. Three fractions of ladle slag, two of which were based on different slag formers, have been characterised using XRF, XRD and calorimetric analysis. Commonly known hydraulic minerals such as mayenite, tricalcium aluminate and dicalcium silicate were detected during analysis. An important aspect in the utilisation of ladle slag is the slag handling methodology. Therefore, this study also highlights and discusses the need to reconsider slag handling procedures concerning unnecessary exposure to weathering and the possible need for further processing of the slag in order to better employ the inherent hydraulic properties of this material. [ABSTRACT FROM AUTHOR]

This paper provides an informative basis on MgO saturation in secondary metallurgical slags by conducting thermo-chemical calculations in the ternary base system AlO-CaO-SiO at 1600 °C, 1650 °C and 1700 °C using FactSage 6.0. The results for lime-aluminate and lime-silicate slag are displayed in a straightforward and illustrative manner. In addition, approximate equations describe the temperature dependencies: a temperature rise of 50 °C increases the MgO saturation limit by about 1 wt. %. [ABSTRACT FROM AUTHOR]

Surface quality of continuously cast is strongly influenced by the interfacial tension between steel and mould flux slag. The meniscus shape and the inclusion entrapment are directly determined by interfacial tension. To achieve a better understanding of the continuous casting process, the interface between four commercial steels and the mould fluxes used at the continuous casting of each steel grade have been investigated. The situation at this interface is determined by the surface tension of steel and slag respectively and also by the mass transfer occurring across the interface. The surface tensions of the mould flux slags have been measured by sessile drop method. The results indicate that the surface tension of mould flux slags decreases with increasing temperature but does not vary so much within the present composition range. Interfacial tensions between steel samples and mould flux slags have been measured in the same way with the aid of X-ray unit. Estimation of interfacial tension from the steel and slag composition was done by applying empirical models. The measured and the calculated values were in agreement. The interfacial tension was lower for higher alloyed steel grades according to both experiments and calculations though the influence of surface active elements is significant. [ABSTRACT FROM AUTHOR]

The viscosities of solid-liquid mixtures were experimentally determined for silicon oil-paraffin system at room temperature and solid-liquid oxide mixture at steelmaking temperature. The use of oil-paraffin systems was to confirm the results of high temperature measurements, the experimental conditions being very difficult to control. The silicon oil- paraffin mixtures behaved Newtonian until the particle fraction reached 0.15. At this fraction, the mixture started deviate from Newtonian flow; though some average values could still be collected with very high uncertainty. Liquid-2CaO.SiO mixtures and liquid-MgO mixtures were studied at steelmaking temperature with carefully prepared particle fractions and well controlled conditions. Liquid-2CaO.SiO mixture behaved Newtonian even when the particle fraction reached 0.1. The results of both room temperature measurements and steelmaking temperature measurements were used to examine the applicability of the existing models. Einstein-Roscoe equation was found to be the only model applicably for the systems studied. No modification of the model parameter was found necessary, though the particles were not spherical. [ABSTRACT FROM AUTHOR]

CO efflux from soil depends on the availability of organic substances respired by roots and microorganisms. Therefore, photosynthetic activity supplying carbohydrates from leaves to roots and rhizosphere is a key driver of soil CO. This fact has been overlooked in most soil CO studies because temperature variations are highly correlated with solar radiation and mask the direct effect of photosynthesis on substrate availability in soil. This review highlights the importance of photosynthesis for rhizosphere processes and evaluates the time lag between carbon (C) assimilation and CO release from soil. Mechanisms and processes contributing to the lag were evaluated. We compared the advantages and shortcomings of four main approaches used to estimate this time lag: (1) interruption of assimilate flow from leaves into the roots and rhizosphere, and analysis of the decrease of CO efflux from soil, (2) time series analysis (TSA) of CO fluxes from soil and photosynthesis proxies, (3) analysis of natural δC variation in CO with photosynthesis-related parameters or δC in the phloem and leaves, and (4) pulse labeling of plants in artificial CO or CO atmosphere with subsequent tracing of C or C in CO efflux from soil. We concluded that pulse labeling is the most advantageous approach. It allows clear evaluation not only of the time lag, but also of the label dynamics in soil CO, and helps estimate the mean residence time of recently assimilated C in various above- and belowground C pools. The impossibility of tracing the phloem pressure-concentration waves by labeling approach may be overcome by its combination with approaches based on TSA of CO fluxes and its δC with photosynthesis proxies. Numerous studies showed that the time lag for grasses is about 12.5±7.5 (SD) h. The time lag for mature trees was much longer (∼4-5 days). Tree height slightly affected the lag, with increasing delay of 0.1 day m. By evaluating bottle-neck processes responsible for the time lag, we conclude that, for trees, the transport of assimilates in phloem is the rate-limiting step. However, it was not possible to predict the lag based on the phloem transport rates reported in the literature. We conclude that studies of CO fluxes from soil, especially in ecosystems with a high contribution of root-derived CO, should consider photosynthesis as one of the main drivers of C fluxes. This calls for incorporating photosynthesis in soil C turnover models. [ABSTRACT FROM AUTHOR]

Mass exchange between liquid steel and the mould flux leads to the oxidation of some elements in the steel and the reduction of slag components. In the continuous casting process, where metal initially solidifies at the metal-slag interface, reaction products generated there can be cached by the growing solidification front. The disruptions of the interface promote the entrapment of flux particles additionally. They can cause surface defects with quality damages of the cast products as a consequence. These investigations are focused on the contact area between liquid mould flux and metal. The samples were taken from the mould during the continuous casting process. The results show that layers up to approximately 300 nm from the slag/metal interface represent a specific reaction space. The transport of oxygen near the interface and the charge transfer is explained on the basis of the ionic character of the slag. Sodium in this layer on the slag side plays a special role in the oxygen transport besides of the iron ions. The mass transfer rate of oxygen crossing the interface is calculated from measured data and conclusions concerning the stability of the interfacial tension are made. [ABSTRACT FROM AUTHOR]