Concentration Of Iron Particles Research Articles

Effects of gamma radiation on the optical properties of ultrafine iron particle/polystyrene composites

The present research studied the influence of gamma radiation doses on the optical properties and parameters of the tested composite samples consisting of polystyrene polymer as a matrix filled with different concentrations of ultrafine iron particles (0, 10, 20, and 30 wt.%) with an average thickness of 2 µm. Using a UV-1800 Shimadzu spectrophotometer, the optical absorbance and transmittance values of the tested composite samples were measured at room temperature in the wavelength range of 200–800 nm. Optical parameters such as the excitation energy for electronic transitions, optical energy gap, dispersion energy, static dielectric constant, static refractive index, moments of the optical spectrum, optical oscillator strengths, linear optical susceptibility, third-order nonlinear optical susceptibility, carrier concentration to the effective mass ratio, high-frequency dielectric constant, nonlinear refractive index, plasma frequency and long wavelength refractive index were calculated and discussed at different doses of gamma radiation (1, 2, and 6 kGy). The results demonstrate that the optical properties and parameters of the gamma-irradiated composites vary with increasing gamma doses. This variation in values was observed after increased irradiation due to enhanced metal–polymer bonding and due to an increase in the density of the free charges within the metal polymer composites.

A Comparative Study on Various ANN Optimization Algorithms for Magnetorheological Elastomer Carbonyl Iron Particle Concentration Estimation

Estimation particle composition such as particle shape, size, and concentration are crucial prior to the fabrication process of magnetorheological elastomer (MRE) to avoid process repetition due to inaccurate formulation. Currently, most of MRE prediction model were purposely used to predict the rheological properties such as shear stress and dynamic modulus, known as forward model. Nonetheless, very few studies have been reported to be capable able of predicting particle composition particularly in MR materials, which known as inverse model. Therefore, this paper proposed a carbonyl iron particle (CIP) concentration based MRE prediction model using neural network algorithm. Neural network-based machine learning model is more approachable compared to conventional mathematical modelling approach due to easily identify trends and pattern while handling multi-variety data. Various optimization algorithms have been employed such as Adam, RMSprop, SGD, AdaGrad, and Nadam throughout the modelling process. As the results, given shear strain amplitude, magnetic flux density, storage modulus, and loss factor as model input, SGD gave the maximum prediction accuracy with 0.95 and 3.038 MPa of R2 and RMSE, respectively. Hence, this model can be the basis to the MRE material and devices development particularly as the tool to reduce costing and time consuming.

A Vehicle Fleet Study to Investigate the Effect of B20 and B10 Usage on Engine Oil Degradation

The use of blended palm biodiesel has been implemented in Malaysia starting with B5 (5% palm biodiesel blended with 95% petroleum diesel) in 2011, B7 (7% palm biodiesel blended with 93% petroleum diesel) in 2014, and B10 in 2019. Palm biodiesel has been regarded as a reliable petroleum diesel substitute since 1995 following the research and development carried out by MPOB. Six trucks participated in the trial to evaluate the use of B20 and B10 through fleet testing and laboratory investigations. The trucks were divided into two groups according to fuel used. The field trial started in 2019 and ended in 2021. Engine oil and filter samples were taken at 5,000 kilometers intervals between service interval 30,000 kilometers. All the engine oil samples were within their operational service limits at each 5,000 kilometers sampling interval. The average viscosities of used engine oil in B20 group were 12.75 mm2 s-1 and for B10 group 12.98 mm2 s-1. The total basic number (TBN) values for the B20 group was 6.4 mg KOH g-1 and 6.3 mg KOH g-1 on average for B10 group. The wear and contaminants test showed the average iron particles concentrations for B20 and B10 groups were 22 ppm and 25 ppm respectively. In terms of engine oil evaporation, the average zinc and phosphorus concentrations reduced by only 20% for both vehicle groups. The average values for soot in oil showed that the B20 group had 10% less soot build-up compared to B10 group. The use of B20 had affected engine oil quality with minimal advantages for soot in oil and iron particle concentrations.

Quantifying platinum binding on protein-functionalized magnetic microparticles using single particle-ICP-TOF-MS.

This work describes an analytical procedure, single particle-inductively coupled plasma-time-of-flight-mass spectrometry (SP-ICP-TOF-MS), that was developed to determine the platinum binding efficiency of protein-coated magnetic microparticles. SP-ICP-TOF-MS is advantageous due to its ability to quasi-simultaneously detect all nuclides (7Li-242Pu), allowing for both platinum and iron (composition of magnetic microparticles) to be measured concurrently. This method subsequently allows for the differentiation between bound and unbound platinum. The 1 μm magnetic microparticles were fully characterized for their iron concentration, particle concentration, and trace element composition by bulk digestion-ICP-MS and SP-ICP-TOF-MS. The results of both approaches agreed with the certificate values. Using the single particle methodology the platinum loading was quantified to be to 0.18 ± 0.02 fg per particle and 0.32 ± 0.02 fg per particle, for the streptavidin-coated and azurin-coated microparticles, respectively. Both streptavidin-coated and the azurin-coated microparticles had a particle-platinum association of >65%. Platinum bound samples were also analyzed via bulk digestion-based ICP-MS. The bulk ICP-MS results overestimated platinum loading due to free platinum in the samples. This highlights the importance of single particle analysis for a closer inspection of platinum binding performance. The SP-ICP-TOF-MS approach offers advantages over typical bulk digestion methods by eliminating laborious sample preparation, enabling differentiation between bound/unbound platinum in a solution, and quantification of platinum on a particle-by-particle basis. The procedure presented here enables quantification of metal content per particle, which could be broadly implemented for other single particle applications.

Process Flow Charts and Recommendations for Processing of Bauxite with Increased Contents of Iron and Fine Particles of Valuable Components

Process Flow Charts and Recommendations for Processing of Bauxite with Increased Contents of Iron and Fine Particles of Valuable Components

Multi‐physical honeycomb metastructure fabricated by fused deposition modeling with broadband radar absorption and mechanical resistance for drones

AbstractComplex structural configuration design is necessary for dielectric‐magnetic lossy composites to achieved broadband microwave absorption in civil and defense applications. Based on the unique space filling characteristic of fractal structure, the honeycomb metastructure can possess microwave absorption and mechanical resistance. However, traditional molding technique was difficult to realize complex shape of metastructure. Herein, the dielectric‐magnetic filament with different concentration of carbonyl iron particles was fabricated by high‐temperature extrusion process. The multi‐physical honeycomb metastructure with gradient layers was printed by fused deposition modeling (FDM) in a large size. The printed dielectric‐magnetic samples exhibited strong dielectric‐magnetic loss with high printing quality. The honeycomb metastructure achieved broadband microwave absorption in the −10 dB bandwidth of 9.6–18 GHz with tensile strength of 31 MPa. The results indicate that FDM is useful to fabricate metastructure with complex shape for broadband microwave absorption. The dielectric‐magnetic properties of filament are magnified by metastructure design. The proposed design‐fabrication process is promising for functional structure realization with complex shape in the future.Highlights1. Magnetic filament was fabricated for functional 3D printing.2. Structural magnetic dissipation mechanism for microwave was presented.3. Magnetic metastructure was designed and printed for broadband absorption.4. Integrated design of mechanical and electromagnetic function was presented.5. Structural absorption effect of honeycomb metastructure was revealed.

An experimental investigation on the matrix dependent rheological properties of MRE

The rheological properties of magnetorheological elastomers are influenced by magnetically sensitive fillers and the elastomer matrix. The ability to respond to an external magnetic field is imparted by the fillers, while the load-bearing capability is determined by the matrix type. In this paper, the effect of matrix material on the properties of magnetorhological elastomer is explored experimentally. Carbonyl iron particle content is varied by 0%, 15% and 25% by volume to produce magnetorheological elastomer samples using natural rubber, silicone rubber and nitrile butadiene rubber matrices. Forced transmissibility test approach was employed to evaluate the field induced variations in the dynamic stiffness and loss factor of magnetorheological elastomers. The dynamic stiffness of nitrile butadiene rubber is the highest, while that of silicone rubber is the lowest. Addition of carbonyl iron particles significantly improves stiffness, although these gains depend on the properties of unfilled matrix. The addition of 25% by volume of carbonyl iron particle increased the dynamic stiffness of a silicone rubber matrix based magnetorheological elastomer by 67.78%, while the similar change in magnetorheological elastomer with nitrile butadiene rubber matrix was 38.58%. The field dependent response of magnetorheological elastomers is governed by the matrix and ferromagnetic filler concentration. These qualities are higher in magnetorheological elastomer with a low initial dynamic stiffness matrix and lower in magnetorheological elastomers with a stiffer matrix.

Research of Dynamic Characteristics of Bearing Reducers of the TwinSpin Class in the Start-Up Phase and in the Initial Operating Hours

This paper describes the results of research in the field of monitoring dynamic characteristics of the TwinSpin cycloid bearing reducer made by SPINEA. The research in this area resulted from the requirement to monitor the condition of high-precision bearing reducers and to assess the non-linear behavior of the kinematic structures of the monitored bearing reducers, specifically to determine the optimal start-up time of a particular bearing reducer class and to plan its maintenance. The condition of contact surfaces in the operational process was identified, and the lubricant applied to the monitored class of reducers was assessed. Analyses of the applied lubricant were carried out in order to identify and monitor changes in the technical condition of the bearing reducer. The aim of the measurements was to verify the start-up time of the bearing reducer, to assess the correlation between the total content of iron particles in the lubricant and an increase in kinematic backlash in the engagement of cycloidal wheels and reducer bearings after start-up and after about 1000 h of operation, and to propose recommendations to the operator for the implementation of short-term dynamic vibration, noise, and temperature tests before the reducer itself is put into operation.

Research on influence of polishing fluids parameters on processing effects in reciprocating magnetorheological polishing

PurposeThis paper aims to study the influence of the different parameters of magnetorheological polishing fluids (MRP fluids) on the surface roughness and material removal rate (MRR) of the workpiece surface in the reciprocating magnetorheological polishing (RMRP) process.Design/methodology/approachA series of single-factor experiments are performed to evaluate the influence of the concentration of magnetic particles, concentration of abrasive particles and size of abrasive particles on surface processing effects by using the RMRP method. Moreover, the yield stress and viscosity of MRP fluids are studied based on the Bingham plastic model by varying the MRP fluids parameters.FindingsA reasonable parameter of MRP fluids is crucial to the surface roughness and MRR of the workpiece surface, and the optimized parameters are obtained by the single-factor experiments of RMRP. The results are when the concentration of carbonyl iron particles is 40 Vol.%, the concentration of CeO2 is 5 Vol.% and the size of CeO2 is 2.5 µm in the MRP fluids, the surface roughness of the workpiece remarkably decreases to 28 nm from the initial 332 nm and the MRR of the workpiece increases to 0.118 mg/min.Originality/valueIn this study, the single-factor experiments for the different parameters of MRP fluids are studied to polish K9 glass by using the RMRP device, and the yield stress and viscosity of MRP fluids are investigated by rheological experiments, which provides reference for a reasonable selection of the MRP fluids parameter in RMRP process.

Vapor-deposited digenite in Chang’e-5 lunar soil

Frequent impacts on the Moon have changed the physical and chemical properties of the lunar regolith, with new materials deposited from the impact-induced vapor phase. Here, we combined nanoscale chemical and structural analysis to identify the mineral digenite (4Cu2S·CuS) in Chang’e-5 lunar soil. This is the first report of digenite in a lunar sample. The surface-correlated digenite phase is undifferentiated in distribution and compositionally distinct from its hosts, suggesting that it originated from vapor-phase deposition. The presence of an Al-rich impact glass bead suggests that a thermal effect provided by impact ejecta is the main heat source for the evaporation of Cu-S components from a cupriferous troilite precursor, and the digenite condensed from these Cu-S vapors. A large pure metallic iron (Fe0) particle and high Cu content within the studied Cu-Fe-S grain suggest that this grain was most likely derived from a highly differentiated and reduced melt.

Research of iron extraction from primary steelmaking slag

The article examines the issue of involving primary steel making slag in the processing with the extraction of iron and the production of slag, which can be used in the manufacture of construction products. Currently, primary steel slag is not used for the production of construction products due to the large amount of iron, and its use is limited to road construction and in most cases, primary slag is sent to landfills. In the Pavlodar region of the Republic of Kazakhstan, during steel production at electric steel making enterprises, the resulting electric furnace slag and dust are stored in slag dumps. They are practically not used, despite their high content of iron oxides and metallic iron particles (up to 40% by weight in some types of slag). The work experimentally determined the chemical and mineralogical composition of primary electric furnace slag with a total iron content of more than 20%. The slag contains the following minerals: wüstite (FeO), magnetite (Fe3O4), gehlenite (Ca2Al(Al,Si)2O7), merwinite (Ca3Mg(SiO4)2). In the course of experimental studies on the recycling of primary electric furnace smelting slags by reduction induction melting of slag-lime-coke pellets, the possibility of extracting iron in the form of iron-carbon alloys and using the slags for the production of concrete was established.

Mechanical Properties and Microstructural Behavior of Uniaxial Tensile-Loaded Anisotropic Magnetorheological Elastomer

Magnetorheological elastomers (MREs) are well-known for their ability to self-adjust their mechanical properties in response to magnetic field influence. This ability, however, diminishes under high-strain conditions, a phenomenon known as the stress-softening effect. Similar phenomena have been observed in other filled elastomers; hence, the current study demonstrates the role of fillers in reducing the effect and thus maintaining performance. Anisotropic, silicone-based MREs with various carbonyl iron particle (CIP) concentrations were prepared and subjected to uniaxial tensile load to evaluate high-strain conditions with and without magnetic influence. The current study demonstrated that non-linear stress–strain behavior was observed in all types of samples, which supported the experimental findings. CIP concentration has a significant impact on the stress–strain behavior of MREs, with about 350% increased elastic modulus with increasing CIP content. Microstructural observations using field emission scanning electron microscopy (FESEM) yielded novel micro-mechanisms of the high-strain failure process of MREs. The magnetic force applied during tension loading was important in the behavior and characteristics of the MRE failure mechanism, and the discovery of microcracks and microplasticity, which was never reported in the MRE quasi-static tensile, received special attention in this study. The relationships between these microstructural phenomena, magnetic influence, and MRE mechanical properties were defined and discussed thoroughly. Overall, the process of microcracks and microplasticity in the MRE under tensile mode was primarily formed in the matrix, and the formation varies with CIP concentrations.

Microstructured Magnetoactive Elastomers for Switchable Wettability.

We demonstrate the control of wettability of non-structured and microstructured magnetoactive elastomers (MAEs) by magnetic field. The synthesized composite materials have a concentration of carbonyl iron particles of 75 wt.% (≈27 vol.%) and three different stiffnesses of the elastomer matrix. A new method of fabrication of MAE coatings on plastic substrates is presented, which allows one to enhance the response of the apparent contact angle to the magnetic field by exposing the particle-enriched side of MAEs to water. A magnetic field is not applied during crosslinking. The highest variation of the contact angle from (113 ± 1)° in zero field up to (156 ± 2)° at about 400 mT is achieved in the MAE sample with the softest matrix. Several lamellar and pillared MAE structures are fabricated by laser micromachining. The lateral dimension of surface structures is about 50 µm and the depth varies between 3 µm and 60 µm. A systematic investigation of the effects of parameters of laser processing (laser power and the number of passages of the laser beam) on the wetting behavior of these structures in the absence and presence of a magnetic field is performed. In particular, strong anisotropy of the wetting behavior of lamellar structures is observed. The results are qualitatively discussed in the framework of the Wenzel and Cassie–Baxter models. Finally, directions of further research on magnetically controlled wettability of microstructured MAE surfaces are outlined. The obtained results may be useful for the development of magnetically controlled smart surfaces for droplet-based microfluidics.

Ultrafine iron particles/polystyrene composites: effects of gamma radiation and manufacture aging on the AC electrical characterization

The present investigation deals with the effects of the (gamma) γ-radiation and samples’ aging on the ac electrical properties of ultrafine iron polystyrene composites. The composites with an average thickness of 1.07 mm contain different iron particle concentrations (10, 20 and 30) by weight %. The results show that the ac electrical properties of the γ-irradiated composites are different from the non-irradiated ones. Rather relative changes in values after irradiation were registered for the impedance, dielectric constant, and the ac electrical conductivity. After irradiation, both the conductivity and the dielectric constant are enhanced relatively with the impedance becoming relatively lower in value. Also, the results show that the age of the samples affects the ac electrical properties of the tested composites. It has been found that after a few years, the electrical conductivity of the composites becomes lower in value compared to what it was a few years ago, which indicates that composites tend to lose their desired electrical properties with passage of time. So, as a potential solution for this physical behavior, the samples were exposed to γ-radiation in an attempt to enhance the metal–polymer bonding and release more free electrons within the composites. The properties such as impedance, dielectric constant, electrical conductivity of the composites were studied before and after γ-irradiation. Later, these studied electrical properties were compared with results reported few years ago. The frequency range applied in this study is consistent with Jonscher’s power law model.

Approbation of an innovative method of pretreatment of dark fermentation feedstocks

According to the International Energy Agency, only a small part of the full potential of biomass energy is currently used in the world. The annual amount of agricultural waste in the Russian Federation is estimated at about 152 million tons, and the energy potential of animal waste is 201 PJ/year. Anaerobic digestion is an efficient method of converting organic waste into renewable energy sources. Previously, the positive effect of pretreatment of various organic feedstocks in vortex layer apparatus (VLA) on the characteristics of anaerobic digestion and energy efficiency was shown. Currently, there is a significant interest in the world in obtaining biohydrogen from organic waste using the dark fermentation (DF) process. During pretreatment in the VLA, the iron working bodies are abraded and iron particles are introduced into the feedstock of the DF reactor. This may have a positive effect on the production rate and yield of hydrogen, which has not been previously studied. This work is aimed at evaluating the possibility of using the VLA as a method for pretreatment of a dark fermentation feedstock for the intensification of biohydrogen production. To achieve this goal, an experimental setup was constructed. It consisted of a 45 L DF reactor, a VLA and a process control system to collect data on the DF process parameters every 5 min. At a hydraulic retention time in the DF reactor of 24 h and in the VLA of 30 s, the hydrogen content in the biogas increased from 51.1% to 52.2%. At the same time, the pH increased from 3.85 to 4.8–4.9, and the hydrogen production rate increased by 16% to 1.941 L/(L day). The hydrogen yield was 80.9 ml/g VS. Thus, pretreatment of the feedstock in VLA can be an effective way to intensify the DF process; however, further study of the VLA operating modes is required in order to optimize the concentrations of iron particles introduced into the feedstock for the most efficient continuous production of dark fermentative biohydrogen.

Experimental study on magnetorheological polishing fluids composition in reciprocating magnetorheological polishing

As the main factor of magnetorheological polishing (MRP), the magnetorheological polishing fluids (MRP fluids) directly affect the machining results of the workpiece surface. In this study, the preparation and performance test of MRP fluids are carried out. It is to evaluate the polishing effects of the workpiece by experimental design of the prepared MRP fluids composition, that is, the concentration of carbonyl iron particles (CIPs), the concentration of cerium oxide (CeO2), and the size of cerium oxide (CeO2) using reciprocating polishing method and establish regression equation models. Further, the optimum MRP fluids composition parameters are obtained by the optimization of regression models of the ΔRa and MRR, and the correctness of optimization results of regression models is validated by experimental verification. The results show that the ΔRa and MRR of the workpiece are affected by the MRP fluids composition parameters. The optimum MRP fluids composition parameters are found at 40 vol.% concentration of CIPs, 5 vol.% concentration of CeO2, and 7000 mesh size of CeO2. The experimental results of the ΔRa and MRR are deviated by 4.95% and 4.17% from the response results respectively by experimental verification.

Experimental and modeling investigations on the quasi-static compression properties of isotropic silicone rubber-based magnetorheological elastomers under the magnetic fields ranging from zero to saturation field

The isotropic magnetorheological elastomers (MREs) containing three different contents of carbonyl iron particles (CIPs) based on silicone rubber were prepared, and their quasi-static compression properties under various magnetic fields were characterized by a material testing machine with specialized electromagnet. The magneto-induced actuation stress at zero strain condition as well as the deformation stress during compression process of MREs were tested. According to the magnetization model and demagnetizing energy theory, a magneto-induced actuation model of isotropic MREs was proposed. Meanwhile, a magneto-hyperelastic model was established for calculating the magnetic field- and strain-dependent deformation stress of MREs via combining the Neo–Hookean model, the magnetization model, and the magnetic dipole theory. Therefore, a new constitutive model was established to describe compression properties of isotropic MREs by considering the magneto-induced actuation and the magneto-hyperelastic behaviors. Finally, the effect of CIP content and model applicability were analyzed. It is verified that the developed compression model was able to exactly predict the compression properties of isotropic MREs with various CIP contents over the magnetic field range varying from zero field to saturation field by adopting a set of unified model parameters.

Optimization of magnetic field assisted finishing process during nanofinishing of titanium alloy (grade-5) implant using soft computing approaches

ABSTRACT The present study explores the potential of magnetic field assisted finishing (MFAF) in precise finishing of femoral knee implant made of bio-titanium alloy at the nanometric level. The process parameters, viz. rotational speed of tool, feed rate and carbonyl iron particle (CIP) concentration of MFAF have significant influence on the final surface topography of implants and thus selection of optimal set of their values is a difficult but an important task. In the present work, central composite rotatable design of response surface methodology is considered for nanofinishing of titanium alloy based femoral knee implants. Based on the experimental results, a polynomial regression prediction model for surface roughness is established in terms of MFAF process parameters. The fuzzy logic model with the help of ANOVA analysis is employed to analyze the effect of individual and interaction of parameters on surface roughness of implants. Finally, for further optimizing the final surface roughness of knee implant and determining the best settings of MFAF parameters, an improved salp swarm algorithm (ISSA) is proposed by introducing two important enhancements in basic SSA. The results reveal that SSA and ISSA metaheuristics achieved an improvement in final surface finish of knee implant by 4.04% and 14.24%, respectively, in comparison to default experimental trials during finishing.

Magnetoelectric Response of Laminated Cantilevers Comprising a Magnetoactive Elastomer and a Piezoelectric Polymer, in Pulsed Uniform Magnetic Fields.

The voltage response to pulsed uniform magnetic fields and the accompanying bending deformations of laminated cantilever structures are investigated experimentally in detail. The structures comprise a magnetoactive elastomer (MAE) slab and a commercially available piezoelectric polymer multilayer. The magnetic field is applied vertically and the laminated structures are customarily fixed in the horizontal plane or, alternatively, slightly tilted upwards or downwards. Six different MAE compositions incorporating three concentrations of carbonyl iron particles (70 wt%, 75 wt% and 80 wt%) and two elastomer matrices of different stiffness are used. The dependences of the generated voltage and the cantilever’s deflection on the composition of the MAE layer and its thickness are obtained. The appearance of the voltage between the electrodes of a piezoelectric material upon application of a magnetic field is considered as a manifestation of the direct magnetoelectric (ME) effect in a composite laminated structure. The ME voltage response increases with the increasing total quantity of the soft-magnetic filler in the MAE layer. The relationship between the generated voltage and the cantilever’s deflection is established. The highest observed peak voltage around 5.5 V is about 8.5-fold higher than previously reported values. The quasi-static ME voltage coefficient for this type of ME heterostructures is about 50 V/A in the magnetic field of ≈100 kA/m, obtained for the first time. The results could be useful for the development of magnetic field sensors and energy harvesting devices relying on these novel polymer composites.

Loss Factor Behavior of Thermally Aged Magnetorheological Elastomers.

Polymer composites have been widely used as damping materials in various applications due to the ability of reducing the vibrations. However, the environmental and surrounding thermal exposure towards polymer composites have affected their mechanical properties and lifecycle. Therefore, this paper presents the effect of material-temperature dependence on the loss factor and phase shift angle characteristics. Two types of unageing and aging silicone-rubber-based magnetorheological elastomer (SR-MRE) with different concentrations of carbonyl iron particles (CIPs), 30 and 60 wt%, are utilized in this study. The morphological, magnetic, and rheological properties related to the loss factor and phase shift angle are characterized using a low-vacuum scanning electron microscopy, and vibrating sample magnetometer and rheometer, respectively. The morphological analysis of SR-MRE consisting of 30 wt% CIPs revealed a smoother surface area when compared to 60 wt% CIPs after thermal aging due to the improvement of CIPs dispersion in the presence of heat. Nevertheless, the rheological analysis demonstrated inimitable rheological properties due to different in-rubber structures, shear deformation condition, as well as the influence of magnetic field. No significant changes of loss factor occurred at a low CIPs concentration, whilst the loss factor increased at a higher CIPs concentration. On that basis, it has been determined that the proposed changes of the polymer chain network due to the long-term temperature exposure of different concentrations of CIPs might explain the unique rheological properties of the unaged and aged SR-MRE.