Search

Rice is the model C3 crop for investigating the starch biosynthesis mechanism in endosperm because of its importance in grain production. However, little is known about starch biosynthesis in the vegetative organs of rice. In this study, we used novel rice mutants by inserting Tos17 into the starch synthase (SS) IIIb gene, which is mainly expressed in the leaf sheath (LS) and leaf blade (LB), and an ss1 mutant to clarify the differences in roles among SS isozymes during starch biosynthesis. Native polyacrylamide gel electrophoresis (PAGE)/activity staining for SS, using LS and LB of ss mutants, revealed that the lowest migrating SS activity bands on the gel were derived from SSIIIb activity and those of two ss3b mutants were not detected. The apparent amylose content of LS starch of ss3b mutants increased. Moreover, the chain-length distribution and size-exclusion chromatography analysis using ss mutants showed that SSIIIb and SSI synthesize the B2–B3 chain and A–B1 chain of amylopectin in the LS and LB respectively. Interestingly, we also found that starch contents were decreased in the LS and LB of ss3b mutants, although SSI deficiency did not affect the starch levels. All these results indicated that SSIIIb synthesizes the long chain of amylopectin in the LS and LB similar to SSIIIa in the endosperm, while SSI synthesizes the short chain in the vegetative organ as the same in the endosperm.

To clarify the effect of constraint conditions on the kink formation, fabrication process of the texture and porosity controlled Ti3SiC2 polycrystals was investigated and microstructural evolution during high temperature deformation was examined in it under high temperature uniaxial compression tests at 1200℃. Dense textured Ti3SiC2 sintered body was fabricated by slip casting in the high magnetic field of 12 T and following pressureless sintering at 1400℃ for 1 h. The porosity of the textured Ti3SiC2 was controlled by dispersing polymethyl methacrylate (PMMA) particles into the textured Ti3SiC2 as a spacer media. The highly textured Ti3SiC2 polycrystals with porosity of 8.4 vol％ and 16.7 vol％, respectively, were successfully fabricated by the slip casting in the high magnetic field. After the high temperature uniaxial compression perpendicular to the c-axis of the textured structure, both the porous and dense Ti3SiC2 showed kink formation, which is a common deformation mode for anisotropic layered materials. However, the average rotation angles of the kink boundaries were higher in the porous specimen than in the dense specimen. Since the crystal rotation is necessary for the kink formation, kink bands would be preferably developed in the porous area due to its weaker constraint than in the dense area. It can be concluded from the microstructural analysis that the constrain factor caused by the neighbor grains affects the crystalline rotation, resulting in the kink boundary formation with different rotation angles.

Abstract The effects of Ti and Si addition on the phase equilibrium and mechanical properties of the equiatomic CoCrFeMnNi high entropy alloy (Cantor alloy) were investigated. The phase equilibrium at 1000 °C was determined from the result of X-ray diffraction and electron probe micro-analysis. Ti addition stabilizes the $$\sigma$$ σ phase, A12 phase and C14-Laves phase, while Si addition stabilizes the A13 phase. The phase relationships were represented by projection onto (Co, Fe, Mn, Ni)–Cr–X(Ti or Si) isothermal ternary cross-section at 1000 °C in Co–Cr–Fe–Mn–Ni–X senary system. Tensile tests were conducted on Cantor-based fcc single solid solution alloys with Ti or Si dissolution at room temperature. The 0.2% yield strength and ultimate tensile strength increased with either element addition. The Ti-added alloy showed higher strength than the Si-added alloy. The difference in ductility in the alloys is related to their strain hardening behavior in the higher strain range. Graphic abstract

The elastic properties of a single-crystalline Ti3SiC2 MAX phase with a nanolayered crystal structure, comprising Ti-Si and two distinct Ti-C bonding layers, that had remained unclear because of the difficulty in growing large single crystals, were studied. Rather than unavailable large single crystals, polycrystalline samples with a crystallographic texture were prepared. By analyzing the polycrystalline elastic constants on the basis of an inverse Voigt–Reuss–Hill approximation, the elastic properties of a single crystal Ti3SiC2 with a hexagonal symmetry were determined. This revealed that the single-crystalline Young's modulus was almost isotropic despite its highly anisotropic layered structure. The shear modulus for (0001) 〈 11 2 ¯ 0 〉 was higher than that for {11 2 ¯ 0}[0001] in contrast to the basal slip-dominated plastic deformation reflecting the layered structure. Furthermore, first-principles calculations revealed that heterogeneous interlayer elastic deformation caused by the stabilization of Ti-Si bonding is the origin of the elastic isotropy in a Ti3SiC2 MAX phase.

Nanoindentation tests were conducted near the grain boundary (GB) of the Al-Mg-Si alloy, and the influence of GB character on the aging precipitation behavior and the mechanical properties was confirmed. After obtaining the GB characters by electron back scattered diffraction (EBSD) analysis and nanoindentation tests were carried out on under aged, peak aged, and over aged samples. And then, the indentation areas were observed by back scattered electrons imaging (BSE) in order to identify indentation positions to the GB. In this study, for the GB character. focusing on the rotation angle, the high-angle GB (HAGB) and the low-angle GB (LAGB) were selected. In addition, coincidence site lattice GBs (CSL) were selected as the special GB. In the 180t under-aged sample, the nano-hardness near GB is higher than that far from GB, while 1801 peak-aged and 250t aged samples, the nano-hardness is tower than that far from GB. Then the amount of change in hardness of HAGB was larger than that of the LAGB. This suggests that the GB character affects the aging precipitation behavior and mechanical properties.

Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) enable the visualization of three-dimensional (3D) microstructures ranging from atomic to micrometer scales using 3D reconstruction techniques based on computed tomography algorithms. This 3D microscopy method is called electron tomography (ET) and has been utilized in the fields of materials science and engineering for more than two decades. Although atomic resolution is one of the current topics in ET research, the development and deployment of intermediate-resolution (non-atomic-resolution) ET imaging methods have garnered considerable attention from researchers. This research trend is probably not irrelevant due to the fact that the spatial resolution and functionality of 3D imaging methods of scanning electron microscopy (SEM) and X-ray microscopy have come to overlap with those of ET. In other words, there may be multiple ways to carry out 3D visualization using different microscopy methods for nanometer-scale objects in materials. From the above standpoint, this review paper aims to (i) describe the current status and issues of intermediate-resolution ET with regard to enhancing the effectiveness of TEM/STEM imaging and (ii) discuss promising applications of state-of-the-art intermediate-resolution ET for materials research with a particular focus on diffraction contrast ET for crystalline microstructures (superlattice domains and dislocations) including a demonstration of in situ dislocation tomography.

Early stages of ordering in dilute Al–0.69(at.%)Mg–0.31(at.%)Si alloy, aged at 373 K for 120 h and 7200 h and at 453 K for 20 h, have been studied using scanning transmission electron microscopy techniques. Starting from the solute enrichment in (110)-type parallel planes, merely after 120 h of aging, isothermal growth at 373 K has been observed to lead to the formation of the small-ordered region after 7200 h of aging. Scanning transmission electron microscopy images from the aforesaid three varieties of samples and the corresponding Fourier-transformed images have been the basis to suggest the possible path of evolution of β″ ordering in this dilute alloy. Based on this, the present study reveals the mechanism of formation of silicon pillar, which is the early stage of β″ that transforms to a fully developed β″. This corroborates with the concept of getting the final β″-strengthened product from an under-aged alloy by a suitable heat treatment.

The effect of Cu-addition on age-hardening and precipitation have been investigated by hardness measurement, tensile test, high resolution transmission electron microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) techniques. Higher hardness, strength, and lower elongation were caused by increasing amount of Zn + Mg because of increased number density of precipitates. Cu addition also provided even higher peak hardness, strength, and lower elongation. The alloy containing highest Cu content had fine precipitates of GPB-II zones or the second clusters, in the precipitate free zones (PFZs) and the matrix, together with η′/η in the matrix from the early stage of aging. Two regions have been confirmed as the PFZs in the peak aged alloy containing highest Cu: (i) nearest to grain boundary (GB) about 70 nm in width (n-PFZ) and (ii) conventional PFZ about 400 nm in width which can be confirmed by conventional TEM (con-PFZ). The con-PFZ contains fine precipitates consisting of GPB-II zones or the second clusters, even for 2 minutes of aging at 473 K which were not present in the n-PFZ. The fine precipitates, GPB-II zones or the second clusters in the con-PFZ and the matrix disappeared at overaged condition. The Japan Institute of Light Metals

A new class of high-temperature materials based on refractory elements was investigated with an aim to improve the energy efficiency of thermal power plants. Alloys based on Nb and Mo composed of BCC solid solution (BCCss) (Nb-Mo) and T2-silicide (Nb,Mo)5(Si,B)3 are promising candidates as high-temperature materials. Further investigation on the alloy phase equilibria of this system is required to improve the mechanical properties and oxidation resistance through optimization of the phase compositions. Cr is one candidate to modify the properties of the alloy because Cr is expected to stabilize the T2 compound phase along with B. Here, the phase equilibria among BCCss and the T2 compound are widely investigated in the Cr-Mo-Nb-Si-B system, and a BCCss-T2 two-phase microstructure is found in Mo-rich alloys. The B/Si ratio in the T2 phase increases with the Cr content, while almost no B solubility was found in BCCss. As the Si content increases in alloys, the A15 silicide phase ((Cr, Mo, Nb)3Si) and/or Laves phase appear. Nanoindentation tests were conducted to investigate the mechanical properties of the BCCss phase of the alloys in the Cr-Mo-Nb-Si-B system. The nanohardness and reduced elastic modulus of these alloys tended to be higher with an increase in Cr.

It is well known that various elements substitute for a certain sub-lattice of intermetallic compounds. There have been various experimental investigations of the effects of substituted elements on mechanical properties, however, there are few reports describing the effects of multi-element substitution. In the present study, L12-type compounds A3B (Ni3Al and Co3(Al,W)) were selected as model compounds because their substitution behavior is well known. It was reported that various elements such as Ni, Co, Cu, Pd and Pt occupy the A-site, whereas Al, Si, Ga, Ge, Ti, V, Nb, Ta, Mo, and W occupy the B-site. These elements are expected to introduce local lattice distortion, which may affect the motion of dislocations over a wide range of temperatures. Several alloys composed of five or more elements including Ni, Co, Al, Mo, and W, were prepared using an Ar-arc melting machine and heat-treated. Several alloys were found to include an (Ni, Co)3(Al, Mo, W, …)-L12 compound as a constituent phase. The nano-hardness of these L12 phases was higher than that of the high-strength Co3(Al,W)-L12 compound, confirming that multi-element substitution is an effective way to improve the mechanical properties of an intermetallic compound without decreasing the phase stability.

An as-cast Mg94Zn2Y4 alloy has been subjected to compression and equal channel angular pressing separately; the resultant microstructure was characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD). The as-cast Mg94Zn2Y4 alloy contains a long-period stacking ordered (LPSO) phase and a Mg24Y5 phase. After the compression, kink boundaries are observed in the LPSO phase and are composed of straight basal ⟨a⟩ dislocations. The dislocation arrangement in the kink boundaries of the LPSO/Mg mixture (alternate thin layers of LPSO and Mg) is similar to that in the LPSO phase. The rotation axes of the kink boundaries in LPSO/Mg are preferentially located in the (0001) plane, though [0001] rotation axis has occasionally been observed. Double kinking and non-basal slip have also been observed in the LPSO/Mg mixture. Dynamically recrystallised Mg grains are observed in the kink boundaries located within the LPSO/Mg mixture, preferentially in the kink boundaries with high misorientation angles. The kink boundary acts as the nucleation site for dynamic recrystallisation due to the high energy stored.

We elucidate the microstructural evolution in MgB2 wires fabricated at two different temperatures by the internal Mg diffusion (IMD) method via multiple-scale microstructural observations. The critical current (Ic) of MgB2 wire was enhanced by the IMD method; however, the Ic of MgB2 was not sufficiently high to allow its practical applications. To prepare MgB2 by the IMD method, molten Mg is required to infiltrate the gaps between the B grains and penetrate each B grain. Here, we suggest that controlling the infiltration and penetration behaviors of Mg are key to enhancing the Ic of MgB2 fabricated by the IMD method. One reason for the decrease in Ic is the existence of residual B grains in the MgB2 crystalline region, which has an area fraction of 25% even in the MgB2 wire exhibiting the highest Ic. The amount of residual B grains, which formed due to the insufficient penetration distance of Mg atoms in the B grain, decreased after high-temperature treatment. However, the microstructure of the MgB2 wire fabricated at a temperature higher than the melting point of Mg was non-uniform because Mg infiltrated the gap between the B grains rapidly and non-uniformly. Thus, optimization of heat treatment temperature can effectively control the infiltration and penetration of Mg in the B grains, yielding uniform microstructures.

The effects of thermally stabilized particles on the recrystallization behavior of an Al–Mg–Si alloy were investigated to obtain the fundamental knowledge for controlling the microstructure, texture, and mechanical properties of this alloy. In this study, the Al–Mg–Si–Sc–Zr alloy was cast, homogenized, and hot-rolled. Three types of spherical Al3(Sc, Zr) particles with L12 structure, rod-like incoherent, spherical semi-coherent, and spherical incoherent particles, were observed in a hot-rolled sample of the Al–Mg–Si–Sc–Zr alloy using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and energy-dispersive X-ray spectroscopy (EDS). In addition, three-dimensional electron tomography (3D-ET) and STEM-EDS revealed that all particles have a core-shell structure with a Sc-enriched core and a Zr-enriched shell. It is considered that these particles are formed during casting, homogenized treatment, and hot rolling. The crystal orientation distribution of the sample after cold rolling indicated that the presence of Al3(Sc, Zr) particles may interfere with the recrystallization (grain growth) until 600°C. Comparison with the driving force of primary recrystallization and grain growth, and the pinning force of Al3(Sc, Zr) particles, showed that these particles mainly contribute to the suppression of grain growth. The results of an in-situ heating SEM/EBSD analysis of the cold-rolled Al–Mg–Si–Sc–Zr alloy supported this suggestion.

Nanoindentation tests were conducted near the grain boundary (GB) of the Al-Mg-Si alloy, and the influence of GB character on the aging precipitation behavior and the mechanical properties was confirmed. After obtaining the GB characters by electron back scattered diffraction (EBSD) analysis, nanoindentation tests were carried out on under-aged, peak-aged, and over-aged samples. And then, the indentation areas were observed by back scattered electrons imaging (BSE) in order to identify indentation positions with respect to the GB. In this study, for the GB character, focusing on the rotation angle, the high-angle GB (HAGB) and the low-angle GB (LAGB) were selected. In addition, coincident site lattice GBs (CSL) were selected as the special GB. In the 180°C under-aged samples, the nano-hardness near GB is higher than that far from GB, while 180°C peak-aged samples, the nano-hardness is lower than that far from GB. Then the range near the GB where the hardness changes was larger at HAGB than at LAGB and CSL3. This suggests that the GB character affects the aging precipitation behavior and mechanical properties.

Al3Nb is known as a high oxidation resistant material, while it is quite brittle. As the fracture toughness of Al3Nb single crystal and its dependence on the composition are not obtained, the micro-sized fracture testing proposed by Suzuki et al. was performed. Al3Nb single crystal micron-order size cantilevers with a chevron-notch were fabricated in a grain of two-phase polycrystalline alloys by using FIB (Focused Ion Beam). From the load-displacement curves during the bending by a nanoindenter, the average value of fracture toughness of Nb-rich Al3Nb is evaluated to be 2.90 MPam1/2, while the fracture toughness of Al-rich Al3Nb is also evaluated to be 2.82 MPam1/2. From this result, the fracture toughness of Al3Nb is less dependent on its Al/Nb ratio. Furthermore the fracture toughness of Al3 (Nb, V) was evaluated to be 2.82 MPam1/2.The fracture toughness of Al3Nb is seemingly insensitive to V addition.

For the improvement of oxidation resistance of Nb-based alloys, PdAl-B2 is expected as Al reservoir for Al2O3 surface layer because it is in equilibrium with Nbss (bcc) phase. However, PdAl forms cracks during casting caused by B2 -> β’ transformation. To suppress B2 -> β’ transformation, Rh, Ru and Ir were chosen as additive elements. It is found that bcc / B2 two-phase field in Nb-Pd-Ir-Al system is limited to be small fraction of Ir, while (Pd,Rh)Al-B2 is in equilibrium with bcc solid solution in a wide composition range and addition of Rh prevents occurrence of B2 -> β’ transformation. Composition range of (Pd,Ru)Al-B2 in equilibrium with bcc phase is wider than (Pd,Ir)Al-B2 but narrower than (Pd,Rh)Al-B2. Rh and Ru addition are also beneficial for improving eutectic temperature of Nb-bcc / B2 aluminide two-phase alloys.

To evaluate heterogeneous strain distribution developed by pre-deformations in dual phase (DP) steel accurately, a combinational technique of Electron Backscatter Diffraction (EBSD) and Digital Image Correlation (DIC) methods was newly introduced in this study. A good correlation is established between kernel average misorientation calculated by EBSD and local equivalent strain measured by DIC in ferrite matrix of DP steels regardless of the difference in deformation process, which means that an EBSD orientation map can be easily converted into an applicative strain map by employing the individual correlation formula. This new technique reveals that very large strain region is locally formed within dozens of micrometer from the punched edge in a punched DP steel. On the other hand, hard martensite grains dispersed in DP steel remarkably promote the heterogeneity of strain distribution in ferrite matrix. As a result, the large strain region is also developed in the form of bands in a cold-rolled DP steel by only 60% thickness reduction at least, as if it is affected by the distribution and morphology of martensite grains. In addition, the local strain mapping demonstrates that the equivalent strain of the large strain band in cold-rolled material is comparable to that of the heavily deformed edge in punched one. The very large strain band in ferrite matrix is characterized by ultrafine grained structure, which leads to the possibility for the losing ductility in ferrite matrix and the martensite cracking.

Creep and anelastic backflow behaviors of pure copper (4N Cu) with grain size d g =40 μm were investigated at low temperatures of T T m ( T m is melting point) and ultra-low creep rates of ɛ ˙ =1×10 −10 s −1 by a high strain-resolution measurement (the helicoid spring specimen technique). Analysis of creep data was based on the scaling factors of creep curves instead of the conventional extrapolated steady-state creep rate. Power-law creep equation is suggested to be the best for describing the primary transient creep behavior, because the pre-parameter does not apparently change with elapsed time. The observed anelastic strains are 1/6 of the calculated elastic strains, and linear viscous behavior was identified from the logarithm plot of the anelastic strain rate versus anelastic strain (slope equals 1). Therefore, the creep anelasticity is suggested to be due to the unbowing of there-dimensional network of dislocations.

To evaluate heterogeneous strain distribution developed by pre-deformations in dual phase (DP) steel accurately, a combinational technique of Electron Backscatter Diffraction (EBSD) and Digital Image Correlation (DIC) methods was newly introduced in this study. A good correlation is established between kernel average misorientation calculated by EBSD and local equivalent strain measured by DIC in ferrite matrix of DP steels regardless of the difference in deformation process, which means that an EBSD orientation map can be easily converted into an applicative strain map by employing the individual correlation formula. This new technique reveals that very high strain region is locally formed within dozens of micrometer from the punched edge in a punched DP steel. On the other hand, hard martensite grains dispersed in DP steel remarkably promote the heterogeneity of strain distribution in ferrite matrix. As a result, the high strain region is also developed in the form of bands in a cold-rolled DP steel by only 60% thickness reduction at least, as if it is affected by the distribution and morphology of martensite grains. In addition, the local strain mapping demonstrates that the equivalent strain of the high strain band in cold-rolled material is comparable to that of the heavily deformed edge in punched one. The very high strain band in ferrite matrix is characterized by ultrafine grained structure, which leads to the possibility for the losing ductility in ferrite matrix and the martensite cracking.

Multi-scale characterization techniques, including computed tomography (CT) based on serial sectioning by focused ion beam (FIB) and scanning transmission electron microscopy (STEM), have been employed to elucidate the microstructural hierarchy inside yttria (Y2O3) dispersed copper alloys designed for fusion reactors. The alloys were fabricated by the combination of mechanical alloying of metal and oxide powders and subsequent hot isostatic pressing. Optical microscopy, together with electron micro-probe analysis revealed bimodal size distribution of powders, where coarse Cu powders of several hundred micrometer are composed of metallic core surrounded by a crust of Cu oxides, while fine powders of several ten micrometer are mostly of oxides. Scanning electron microscopy (SEM) on the fabricated bulk alloys revealed heterogeneous inner structure, which is best described by an assembly of large Cu grain regions bordered by small Cu grain regions. Distribution of Y2O3 particles are visualized three dimensionally by serial sectioned FIB-SEM images and by CT-STEM, both of which revealed the particles are enriched in small Cu grain regions. These multi-scale characterization, together with mechanical bend testing, demonstrated that excess Y2O3 particles in grain boundaries leads to brittle fracture, while that large Cu grains are responsible for the ductility of the alloy.

Highly luminescent red emitting Gd2O3:Eu3+, Li+ nanophosphor has been synthesized by the solvothermal combustion of the metal–citrate complex in diethylene glycol medium. The morphology and luminescence properties of these nanophosphors are found to be highly sensitive to the extent of lithium ion compensation. It is found that lithium ions promote grain growth and alter the morphology of the Gd2O3:Eu3+ nanophosphor from nearly spherical to cobblestone like. A significant enhancement in intensity of luminescence and quantum efficiency is observed in lithium compensated nanophosphors. The highest emission intensity is observed for the Gd1.75Eu0.1Li0.15O3 nanophosphor, about 1.83 times that of Gd1.9Eu0.1O3 and is attributed to the enhanced intra 4f–4f emission transitions arising from the modifications of the crystal field and distortion of the local symmetry around the europium ions. The luminescence decay profiles are found to be single exponential in nature and the lifetime measured was 1.36 ms for the Gd1.75Eu0.1Li0.15O3 nanophosphor. The chromaticity coordinates of these nanophosphors indicated high colour purity. Judd–Ofelt intensity parameters indicated that lithium compensation increases the polarization of the local environment and an increase of covalency and asymmetry around the europium ions.

Dual Phase (DP) steel is used in automotive body parts for weight saving and crashworthiness, however there is an issue of DP steel in low stretch flange ability evaluated by hole expanding tests. In order to improve stretch flange ability of DP steel, it is important to estimate the damage of punching quantitatively and to clarify the change of microstructure before and after punching because the hole expansion ratio is decided in the ductility remained after pre-strain equivalent to punching. Therefore we tried to measure the damage of punching by unique techniques of Electron Backscatter Diffraction (EBSD), nano-indentation and micro-tensile testing and to observe fracture surface by Scanning Transmission Electron Microscope (STEM). Average EBSD-Kernel Average Misorientation (KAM) value and pre-strain damage have strong correlation, thus average KAM value can become the index of the damage. The nanohardness and tensile strength using micrometer-sized specimens increased with increasing average KAM value in the ferritic phase as approaching the punching edge. A shear type fracture occurred without necking in the specimen cut out in the area of the edge. The ultrafine-grained ferritic microstructure was observed in the sample cut out in the same area with STEM. It seems that the ductility loss of the punched DP steel was probably attributed to localized strain into the ultrafine-grained ferritic microstructure.

We have performed combined high-resolution microstructural and grain orientation analyses to understand the key microstructural factors associated with high intergranular transport current in polycrystalline bulk forms of MgB 2 . The ex-situ method can produce MgB 2 with relatively high packing factors; nevertheless, the connectivity of MgB 2 fabricated by the ex-situ method (ex-situ MgB 2 ) was less than that of in-situ MgB 2 . The poor connections between MgB 2 grain aggregates cause the low connectivity of ex-situ MgB 2 . Plate-like pores are present between the aggregates of MgB 2 grains in ex-situ MgB 2 ; these pores remain even after prolonged self-sintering at high temperatures. In addition, MgB 2 crystals decompose to MgB 4 in sintering for a long period. Moreover, MgO particles are formed between MgB 2 grain aggregates and inhibit interaggregate connections. In contrast, in-situ MgB 2 fabricated at the same sintering conditions exhibits spherical pores between MgB 2 grains, resulting in a uniform pore distribution and intergranular connection. These problems must be addressed to further enhance the connectivity in ex-situ MgB 2 .

Sandwich panels were tested according to the ISO 13784-1 standard by the Fire Insurers Laboratories of Korea and the Korea Institute of Construction Technology in Korea, the Royal Institute of Tech...

This paper aims to explain and analyze the test results of the fire behavior of real-size bed mattress products when subjected to an open flame burner system with a total heat supply of 27 kW accor...