Mixed Flux Research Articles

Local reorganisation of the intermediate mixed state in niobium below the critical depinning current

Abstract The intermediate mixed state under the influence of a transport current was studied using small angle neutron scattering. 
The internal magnetic domain structure consisting of mixed state domains and flux free Meissner state domains was observed to rearrange at intermediate currents well before the critical depinning current marked by a finite voltage. The local rearrangement can be traced by the changes in the vortex lattice Bragg peak scattering and the current-induced anisotropy of the low-$q$ scattering connected to the internal magnetic domain structure. 
It is argued, that the local reorganisation prior to the critical depinning current is inherently linked to the interplay of the pinning landscape with the vortex lattice domain structure governed by the physics of the intermediate mixed state.

Role of QBO and MJO in Sudden Stratospheric Warmings: A Case Study

The impact of the quasi-biennial oscillation (QBO) and Madden–Julian oscillation (MJO) on the dynamics of major sudden stratospheric warmings (SSWs) observed in the winters of 2018, 2019, and 2021 is investigated. Using data from the MERRA-2 reanalysis, we analyze the daily mean variability of critical atmospheric parameters at the 10 hPa level, including zonal mean polar cap temperature, zonal mean zonal wind, and the amplitudes of planetary waves 1 and 2. The results reveal dramatic increases in polar cap temperature and significant wind reversals during the SSW events, particularly in 2018. The analysis of planetary wave (PW) amplitudes demonstrates intensified wave activity coinciding with the onset of SSWs, underscoring the pivotal role of PWs in these stratospheric disruptions. Further examination of outgoing long-wave radiation (OLR) anomalies highlights the influence of QBO phases on tropical convection patterns. During westerly QBO (w-QBO) phases, enhanced convective activity is observed in the western Pacific, whereas the easterly QBO (e-QBO) phase shifts convection patterns to the maritime continent and central Pacific. This modulation by QBO phases influences the MJO’s role during SSWs, affecting tropical and extra-tropical weather patterns. The day-altitude variability of upward heat flux reveals distinct spatiotemporal patterns, with pronounced warming in the polar regions and mixed heat flux patterns in low latitudes. The differences observed between the SSWs of 2017–2018 and 2018–2019 are likely related to the varying QBO phases, emphasizing the complexity of heat flux dynamics during these events. The northern annular mode (NAM) index analysis shows varied responses to SSWs, with stronger negative anomalies observed during the e-QBO phase compared to the w-QBO phases. This variability highlights the significant role of the QBO in shaping the stratospheric and tropospheric responses to SSWs, impacting surface weather patterns and the persistence of stratospheric anomalies. Overall, the study demonstrates the intricate interactions between stratospheric dynamics, QBO, and MJO during major SSW events, providing insights into the broader implications of these atmospheric phenomena on global weather patterns.

Effects of Rb-Based Mixed Fluxes on Surface Crystal Growth of BaTaO₂N and Photocatalytic Activities

Photocatalytic water splitting has been actively studied from the viewpoint of environmental issues as a method to produce hydrogen, a clean energy source, without using fossil fuels. Oxynitride BaTaO2N is a visible light responsive photocatalyst and is expected to have high energy conversion efficiency for hydrogen production using sunlight. In a previous study, single phase BaTaO2N crystals were successfully grown by the flux method. However, the maximum activity value is only about 500 µmol/h, which is insufficient to produce enough hydrogen for practical use. One of the reasons for this is unoptimized crystal surface, such as crystal face, and lattice defects. Flux method is known as an effective method to control crystal properties, but single flux is difficult to control these crystal properties at the same time. For example, although RbCl flux can reduce defect density by minimizing elemental contamination of BaTaO2N, it is highly volatile and not effective in controlling the crystal surface. Therefore, we considered the use of multiple fluxes at the same time. This allows appropriate modification of factors related to the flux reaction field, such as viscosity, melting point, and solute-solvent interaction, while avoiding elemental contamination. This leads to flexible adjustment of the crystal growth mode, which we believe will bring crystal growth closer to ideal conditions.In this study, the effect of multi-flux on the growth mode and photocatalytic properties of BaTaO2N crystals was investigated. As an example, we report the crystal growth of BaTaO2N using mixed fluxes of RbCl, RbBr, and Rb2CO3. A single RbCl flux provided step-terrace surface structure of the BaTaO2N crystal, while an equimolar mixture of RbCl and RbBr resulted in a flatter and more rounded crystal. The visible-light responsive photocatalytic activity of the BaTaO2N crystals obtained with each flux was evaluated. The photocatalytic H2 evolution value of BaTaO2N grown in RbCl-RbBr mixed flux was about 30% of that grown in RbCl flux. This drastic change in activity may be explained by decrease of active crystal surface, including step-terrace one derived from mixed flux reaction field. We are now investigating the effect of step-terrace structure on photocatalytic activity, by tuning the surface structure using the mixed flux species. In the presentation, we will systematically report fine design of crystal growth, photocatalytic activity, and also the contribution mechanism of the mixed fluxes on them.AcknowledgementThis work was partly supported by the NEDO Green Innovation fund projects, the Strategic Innovation Program (SIP) of the Cabinet Office, and joint research with a company.

Impact of mixed boundary conditions and nonsmooth data on layer‐originated nonpremixed combustion problems: Higher‐order convergence analysis

AbstractThis work explores the theoretical and computational impacts of mixed‐type flux conditions and nonsmooth data on boundary/interior layer‐originated singularly perturbed semilinear reaction–diffusion problems. Such problems are prevalent in nonpremixed combustion models and catalytic reaction models. The inclusion of arbitrarily small diffusion terms results in boundary layers influenced by specific flux conditions normalized by perturbation parameters. We have demonstrated theoretically that the sharpness of the boundary layer is significantly reduced when this normalization is independent of the diffusion parameter. In addition, the presence of a nonsmooth source function gives rise to an interior layer in the current problem. We show that using upwind discretizations for mixed boundary fluxes achieves nearly second‐order accuracy if the first derivatives are not normalized concerning perturbation parameters. This outcome arises from the bounds of a prior derivative of the continuous solution. Furthermore, it is theoretically shown that nearly second‐order uniform accuracy can be attained for reaction‐dominated semilinear problems using a hybrid scheme at the discontinuity point. To ensure the uniform stability of the discrete solution, a transformation is necessary for the corresponding discrete problem. Theoretical results are supported by various experiments on nonlinear problems, illustrating the pointwise rates and highlighting both linear and higher‐order accuracy at specific points.

Identification of Earth's late accretion by large impactors through mass independent Cr isotopes

The late addition of extra-terrestrial material may represent an important source of Earth's volatiles. The composition of impactors can be reconstructed using 54Cr abundances in impact related rocks preserved in the terrestrial record. The average ε53Cr and ε54Cr of Earth's mantle determined from mantle rocks of 3.8 Ga to present are 0.03 ± 0.02 and 0.08 ± 0.04, respectively. Impact melt rocks and spherule beds linked to impact structures larger than 50 km that formed between 3.4 Ga and 66 Ma have ε53Cr ranging from −0.04 to 0.17, and ε54Cr ranging from −0.64 to 1.41. A carbonaceous chondrite-like impactor contribution dominated the Meso- to Paleoarchean spherule layers (> 3.0 Ga), whereas a mixed chondrite flux composed of carbonaceous and non‑carbonaceous chondrites, with a possible contribution of differentiated meteorites is observed in the younger spherule layers (2.5 Ga to 66 Ma). This likely reflects the break-up of distinct asteroid families through time. Although available impact materials are limited, the Cr isotope signatures of materials related to large impacts suggest a change in the composition of crater-forming impactors on Earth, from predominantly carbonaceous chondrite-like more oxidized material during the Archean to predominantly non‑carbonaceous -like more reduced and volatile poor material in recent times. Chromium isotopes suggest that not more than 0.01 wt% of CC-like material added to the Earth's mantle after the Archean. Thus, it is inferred that the mass accreted after 3.0 Ga contributed insignificantly to the water and other volatile element budget of the Earth.

Analysis of flux footprints in fragmented, heterogeneous croplands

An accurate quantification of fluxes from heterogeneous sites and further bifurcation into contributing homogeneous fluxes is an active field of research. Among such sites, fragmented croplands with varying surface roughness characteristics pose formidable challenges for footprint analysis. We conducted two flux monitoring experiments in fragmented croplands characterized by two dissimilar surfaces with objectives to: (i) evaluate the performance of two analytical footprint models in heterogeneous canopy considering aggregated roughness parameters and (ii) analyze the contribution of fluxes from individual surfaces under changing wind speed. A set of three eddy covariance (EC) towers (one each capturing the homogenous fluxes from individual surfaces and a third, high tower capturing the heterogeneous mixed fluxes) was used for method validation. High-quality EC fluxes that fulfill stationarity and internal turbulence tests were analyzed considering daytime, unstable conditions. In the first experiment, source area contribution from a surface is gradually reduced by progressive cut, and its effect on high-tower flux measurements is analyzed. Two footprint models (Kormann and Meixner ‘KM’; analytical solution to Lagrangian model ‘FFP’) with modified surface roughness parameters were applied under changing source area contributions. FFP model has consistently over predicted the footprints (RMSEFFP = 0.31 m−1, PBIASFFP = 19.00), whereas KM model prediction was gradually changed from over prediction to under prediction towards higher upwind distances (RMSEKM = 0.02 m−1, PBIASKM = 8.50). Sensitivity analysis revealed that the models are more sensitive to turbulent conditions than surface characteristics. This motivated to conduct the second experiment, where the fractional contribution of individual surfaces (α and β) to the heterogeneous fluxes measured by the high tower (T3) was estimated using the principle of superposition (FT3 = α FT1 + β FT2). Results showed that α and β are dynamic during daylight hours and strongly depend on mean wind speed (U) and friction velocity (u*). The contribution of fluxes from adjoining fields [1 − (α + β)] is significant beyond 80% isopleth. Our findings provide guidelines for future analysis of fluxes in heterogeneous, fragmented croplands.

Estimating mixed gas fluxes with geochemically informed broadband acoustic methods: What the flux?

Over the past few years, improvements in broadband split-beam echosounders have made it possible to obtain precise measurements of bubble-size distribution and density of gas seeps. Here, we model acoustic volume backscattering of a group of bubbles with a multi-modal size distribution that we matched to real-time acoustical measurement over a gas seep. The results are profiles of bubble size distribution descriptors (e.g., distribution type and parameters), density and ratio of the various components (i.e., gas composition). To test the ability of this methodology to differentiate gas flux composition and estimate gas flux magnitudes, we applied it in a semi-automated fashion on broadband data (12 to 250 kHz) acquired in the Bay of Plenty (NZ) over mixed gas seeps (e.g., CO2, CH4). Model outputs were compared with real-time dissolved gas measurements to constrain gas composition, magnitude, and ground-truth methodologies. The method can be applied to a variety of marine seeps to produce regional flux estimations, improving oceanic carbon budgets and our understanding of downstream feedbacks, such as localized deoxygenation or ocean acidification.

The black hole/string transition in AdS3 and confining backgrounds

String stars, or Horowitz-Polchinski solutions, are Euclidean string theory saddles with a normalizable condensate of thermal winding strings. String stars were suggested as a possible description of stringy (Euclidean) black holes close to the Hagedorn temperature. In this work, we continue the study initiated in [1] by investigating the thermodynamic properties of string stars in asymptotically (thermal) anti-de Sitter backgrounds. First, we discuss the case of AdS3 with mixed RR and NS-NS fluxes (including the pure NS-NS system) and comment on a possible BTZ/string transition unique to AdS3. Second, we present new “winding-string gas” saddles for confining holographic backgrounds such as the Witten model and determine the subleading correction to their Hagedorn temperature. We speculate a black brane/string transition in these models and argue for a possible relation to the deconfined phase of 3+1 dimensional pure Yang-Mills.

Numerical simulation of particle mixing and granulation performance in rotating drums during the iron ore sintering process

Granulation is an important process in iron ore sintering to increase particle size for better permeability. In this study, the granulation of mixed iron ore, coke, and flux in a rotating drum is studied by the discrete element method. The results of mixing indicate that the particle-particle collision number is closely related to the composition of raw materials, and the presence of the drum baffle amplifies the collision number several times. After granulation, the type and quantity of attached small particles on the core particle surface are analyzed, showing that with the water content increasing from 2% to 8%, the number of small particles attached continuously increases. The drum rotating speed does not significantly affect the adhesion of small particles. However, the existence of baffles can significantly increase the number of iron ore small particles adhered to the core particles at the rotating speed of 28 rpm.

Wave Buoy Measurements at Short Fetches in the Black Sea Nearshore: Mixed Sea and Energy Fluxes

Wave buoy measurements were carried out near the northeastern Black Sea coast at the natural reserve Utrish in 2020–2021. In total, about 11 months of data records were collected during two stages of the experiment at 600 and 1500 m offshore and depths of 18 and 42 m. The measured waves propagate almost exclusively from the seaward directions. Generally, the waves do not follow the local wind directions, thus, implying a mixed sea state. Nevertheless, dimensionless wave heights and periods appears to be quite close to the previously established empirical laws for the wind-driven seas. The results of the wave turbulence theory are applied for estimates of spectral energy fluxes and their correspondence to the energy flux from the turbulent wind pulsations. These estimates are consistent with today’s understanding of wind–wave interaction. It is shown that the main fraction of the wind energy flux is sent to the direct Kolmogorov–Zakharov cascade to high wave frequencies and then dissipates in small amounts. Less than 1% of the wind energy flux is directed to the low frequency band (the so-called inverse Kolmogorov–Zakharov cascade), thus, providing wave energy growth.

Sr(Ag1−xLix)2Se2 and [Sr3Se2][(Ag1−xLix)2Se2] Tunable Direct Band Gap Semiconductors

AbstractSynthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid‐state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two‐dimensional Sr(Ag1−xLix)2Se2 layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1−xLix)2Se2 with x up to 0.45. In addition, a new type of intergrowth compound [Sr3Se2][(Ag1−xLix)2Se2] was synthesized upon further reaction of Sr(Ag1−xLix)2Se2 with SrSe. Both Sr(Ag1−xLix)2Se2 and [Sr3Se2][(Ag1−xLix)2Se2] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1−xLix)2Se2 can be precisely tuned via fine‐tuning x that is controlled by only the flux ratio and temperature.

Sr(Ag1-x Lix )2 Se2 and [Sr3 Se2 ][(Ag1-x Lix )2 Se2 ] Tunable Direct Band Gap Semiconductors.

Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid-state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two-dimensional Sr(Ag1-x Lix )2 Se2 layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1-x Lix )2 Se2 with x up to 0.45. In addition, a new type of intergrowth compound [Sr3 Se2 ][(Ag1-x Lix )2 Se2 ] was synthesized upon further reaction of Sr(Ag1-x Lix )2 Se2 with SrSe. Both Sr(Ag1-x Lix )2 Se2 and [Sr3 Se2 ][(Ag1-x Lix )2 Se2 ] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1-x Lix )2 Se2 can be precisely tuned via fine-tuning x that is controlled by only the flux ratio and temperature.

Surface ocean carbon budget in the 2017 south Georgia diatom bloom: Observations and validation of profiling biogeochemical argo floats

Estimates of the partial pressure of CO2 (pCO2) derived from biogeochemical Argo floats have the potential to improve our knowledge of the highly variable and partially observed Southern Ocean carbon sink through sampling at improved temporal and spatial resolution. Here we use the data from six biogeochemical Argo floats to characterise near-surface dissolved inorganic carbon (DIC) concentrations and fluxes at the site of an intense (Chl-a >3 mg m−3) mesoscale diatom bloom situated northwest of South Georgia. Concurrently, we provide independent analysis and validation of the methodology used by the Southern Ocean Carbon and Climate Observational and Modelling (SOCCOM) project for deriving surface pCO2 from float-based pH and oxygen measurements. We compare the float observations with co-located ship data from bottle samples over a month-long period. When compared to data sampled within 24 h and 25 km of each float profile, we find good agreement with a mean offset of −0.005 ± 0.018 (1σ) between float pH and bottle-derived pH. This translates to comparable pCO2 estimates between ship measurements and floats with a mean difference of 2.6 ± 12.8 (1σ) μatm, providing support for the use of biogeochemical Argo float data to supplement shipboard pCO2 measurements in the Southern Ocean. Based on float-derived pCO2 we calculate a sizeable local flux of CO2 of 24 ± 7 mmol C m−2 d−1 (over a 27-day period) from the atmosphere into the surface mixed layer, driven by a large air-sea pCO2 gradient and strong but variable winds. Despite the considerable air-sea flux, the local mixed layer carbon budget appears to be dominated by entrainment and detrainment of carbon-rich waters into and out of the mixed layer. However, given the large uncertainties associated with these fluxes and the significant challenges associated with closing the mixed layer budget, further research is required to refine float-based mixed layer DIC fluxes.

New types of composite scintillators based on the single crystalline films and crystals of Gd3Al5-xGaxO12:Ce garnets

This work presents the results on creation of novel types of composite scintillators based on Ce3+ doped Gd3Al5-xGaxO12 single crystalline films grown by the LPE method using PbO–B2O3 flux onto substrate-scintillators prepared from commercial Gd3Al2.3Ga2.7O12:Ce and Gd3Al2Ga3O12:Ce single crystals. The sets of films with different Ga contents x = 1.75–2.25 and various thicknesses in the 13–150 μm range were grown onto the mentioned substrates. The scintillation properties of the respective epitaxial structures (pulse height spectra, light yield and scintillation decay kinetics) were investigated under excitation by α– (239Pu) particles, β- (90Sr+90Y) particles and γ–quanta (137Cs). The best scintillation properties for simultaneous registration of the mentioned particles and quanta in the mixed radiation fluxes are demonstrated with Gd3Al2.75Ga2.25O12 film/Gd3Al2Ga3O12:Ce substrate epitaxial structure.

Performance of analytical footprint models in heterogeneous landscapes under varying atmospheric stability conditions

Analytical footprint models that simulate the source area of scalar fluxes generally include a fundamental assumption that the fluxes originate from a horizontal, homogeneous surface. It is widely understood that this assumption is often violated in flux studies, especially for sites where there are significant variations in topography, leaf area, photosynthetic pathway and underlying soil properties. An accurate interpretation of the measured flux footprint under heterogeneous canopy condition can help alleviate the problem. We evaluated the performance of analytical models (Hsieh, K&M, and Schuepp) under stable and unstable atmosheric conditions for the homoeneous canopy (Cotton- C3, zm = 3m and Sugarcane- C4, zm = 4m) and heterogeneous canopy (mixed fetch) compared to FFP model in a complex sugarcane-cotton (C3-C4) cropping system. Performance of models were evaluated using a set of three eddy covariance (EC) towers (one each capturing homogenous C3 and C4 fluxes, and a third capturing heterogeneous, mixed (C3-C4) fluxes at zm = 8m). High-quality EC fluxes that fulfil stationarity and internal turbulence tests were analyzed on the basis of daytime, unstable condition datasets. K&M model (Corr >0.75 , RMSE <0.06 , SD <0.006) performed the best in comparison to FFP model flux footprint prediction under unstable atmospheric condition in heterogeneous canopy condition with respect to Hsieh (Corr <0.6, RMSE >0.01 , SD >0.005), and Schuepp analytical model (Corr =0.2, RMSE <0.01, SD>0.2 ). Unstable atmospheric condition is further classified into four categories (neutral, near neutral unstable, unstable, and very unstable). Relative performance of the analytical models was further analyzed with experimental flux tower generated flux footprint under neutral, near neutral unstable, unstable, and very unstable atmospheric condition. FFP model performs the best in heterogeneous canopy condition under varying neutral to very unstable atmospheric condition. We make clear recommendations for future analysis of fluxes in heterogeneous crop lands under varying atmospheric stability condition.

Polymorphism in A3MF6 (A = Rb, Cs; M = Al, Ga) grown using mixed halide fluxes.

Single crystals of A3MF6 (A = Rb, Cs; M = Al, Ga) were grown from mixed alkali chloride/fluoride fluxes in sealed silver tubes. For Cs3AlF6 and Cs3GaF6, two polymorphs were observed at room temperature: m-Cs3MF6 and o-Cs3MF6. For the two Rb containing compositions, only one room temperature polymorph was observed: o-Rb3AlF6 and t-Rb3GaF6, respectively. Simultaneous TGA/DSC and high temperature SCXRD/PXRD were used to study the high temperature behavior of A3MF6. The compounds of all four compositions were found to undergo structure transitions upon heating to the same cubic structure type, c-A3MF6.

Development of the Composite Thermoluminescent Detectors Based on the Single Crystalline Films and Crystals of Perovskite Compounds.

This work is dedicated to the development of new types of composite thermoluminescent detectors based on the single crystalline films of Ce-doped GdAlO3 perovskite and Mn-doped YAlO3 and (Lu0.8Y0.2)AlO3:Mn perovskites as well as Ce and Pr-doped YAlO3 single crystal substrates. These detectors were obtained using the Liquid Phase Epitaxy growth method from the melt solution based on the PbO-B2O3 fluxes. Such composite detectors can by applied for the simultaneous registration of different components of mixed ionization fluxes using the differences between the thermoluminescent glow curves, recorded from the film and crystal parts of epitaxial structures. For creation of the new composite detectors, we considered using, for the film and crystal components of epitaxial structures (i) the different perovskite matrixes doped with the same type of activator or (ii) the same perovskite host with various types of activators. The thermoluminescent properties of the different types of epitaxial structures based on the abovementioned films and crystal substrates were examined in the conditions of β-particles and X-ray excitation with aim of determination of the optimal combination of perovskites for composite detectors. It was shown that, among the structures with all the studied compositions, the best properties for the simultaneous thermoluminescent detection of α- and X-rays were the GdAlO3:Ce film/YAlO3:Ce crystal epitaxial structure.

Discovery of chalcogenides structures and compositions using mixed fluxes

Advancements in many modern technologies rely on the continuous need for materials discovery. However, the design of synthesis routes leading to new and targeted solid-state materials requires understanding of reactivity patterns1-3. Advances in synthesis science are necessary to increase efficiency and accelerate materials discovery4-10. We present a highly effective methodology for the rational discovery of materials using high-temperature solutions or fluxes having tunable solubility. This methodology facilitates product selection by projecting the free-energy landscape into real synthetic variables: temperature and flux ratio. We demonstrate the effectiveness of this technique by synthesizingcompounds in the chalcogenide system of A(Ba)-Cu-Q(O) (Q = S or Se; A = Na, K or Rb) using mixed AOH/AX (A = Li, Na, K or Rb; X = Cl or I) fluxes. We present 30 unreported compounds or compositions, including more than ten unique structural types, by systematically varying the temperature and flux ratios without requiring changing the proportions of starting materials. Also, we found that the structural dimensionality of the compounds decreases with increasing reactant solubility and temperature. This methodology serves as an effective general strategy for the rational discovery of inorganic solids.

Composition Engineering of (Lu,Gd,Tb)3(Al,Ga)5O12:Ce Film/Gd3(Al,Ga)5O12:Ce Substrate Scintillators

The paper addresses the development of composite scintillation materials providing simultaneous real-time monitoring of different types of ionizing radiation (α-, β-particles, γ-rays) in mixed fluxes of particles and quanta. The detectors are based on composite heavy oxide scintillators consisting of a thin single-crystalline film and a bulk single-crystal substrate. The film and substrate respond to certain types of ionizing particles, forming together an all-in-one composite scintillator capable of distinguishing the type of radiation through the different time characteristics of the scintillation response. Here, we report the structure, composition, and scintillation properties under different ionizing radiations of (Lu,Gd,Tb)3(Al,Ga)5O12:Ce films deposited using liquid phase epitaxy onto Gd3(Al1−xGax)5O12:Ce (GAGG:Ce) single-crystal substrates. The most promising compositions with the highest light yields and the largest differences in scintillation decay timing under irradiation with α-, β-particles, and γ-rays were selected. Such detectors are promising for environmental security purposes, medical tomography, and other radiation detection applications.

Recycling red mud to develop a competitive desulfurization flux for Kanbara Reactor (KR) desulfurization process

One of the industrial wastes, red mud, was assessed as an additive to lime, as a new desulfurization flux for the hot metal in the steelmaking process. Since typical red mud contains some amount of iron oxide, a preliminarily reduced red mud was mainly investigated. Pre-reduction of the red mud and execution of mechanical stirring to the hot metal were effective to enhance desulfurization efficiency (extent and rate of the reaction). However, adding more than 20 pct of red mud in the lime/red mud (pre-reduced) flux did not increase the desulfurization rate. In order to assess the desulfurization efficiency in a more quantitative manner, a “DeS Index” was defined as: DeS Index=log[pct S]f[pct S]0−1k′WCaOWS−1. This takes into account the extent, rate, and cost of the desulfurization simultaneously. With this index, it was found that the presently developed red mud (pre-reduced)/lime mixtures showed almost similar desulfurization efficiency compared with those of commercially used desulfurization fluxes. It was even better than a typical lime/fluorspar mixed flux, which is now prohibited from being used in many companies due to its environmentally harmful character. It is emphasized that the desulfurization efficiency should be assessed under the mechanical stirring in order to be used in the KR type desulfurization process.