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A series of fire tests were performed to study the effect of infiltration depth on the burning behavior and fuel residue of porous media bed soaked by liquid fuel. Ethanol was used as liquid fuel and quartz sand was used to naturally stack to form the porous media bed with different infiltration depths within the range of 60–180 mm. Burning rate, internal temperature of porous media bed, flame height, movement speed of fuel vapor zone, and fuel residue percentage was measured and analyzed. Results show that within current test scope, fuel mass loss rate in quasi stable period is negatively correlated with infiltration depth, and the relationship between mass loss rate and infiltration depth can be well characterized by power function. Quasi stable flame height also decreases gradually with the increase of infiltration depth. With the range of 78.5–79.2°C, the temperature growth retardation occurred inside sand bed, and sand bed was hence assessed as a distinct three-zone feature. The movement speed of vapor zone decreases linearly with the increase of infiltration depth, and the maximum measured value is about 0.041 mm/s. Axial temperature distribution of flame and plume can be well characterized based on McCaffery's plume relationship, but the length of continuous flame and intermittent flame zone is shortened to some extent. Within current test range, fuel residue percentage increases with the increase of infiltration depth and particle size, and maximum fuel residual percentage is at 5.29% in the case with 180 mm infiltration depth, which is obviously smaller than previous scholars' results. In addition to the depth of infiltration, the boiling point and viscosity of liquid fuel and the effective thermal conductivity of sand bed are also important influencing factors. [ABSTRACT FROM AUTHOR]

A porous magnetic covalent organic framework, Fe3O4@TPBD-TPA (terephthalaldehyde (TPA) , N, N, N′, N′-tetrakis(p-aminophenyl)-p-phenylenediamine (TPBD)), was synthesized using the Schiff base reaction under mild reaction conditions. This adsorbent exhibited excellent adsorption performance for aflatoxins. The adsorption capacity of Fe3O4@TPBD-TPA for aflatoxins ranged from 64.4 to 84.4 mg/g. A magnetic solid-phase extraction combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method based on Fe3O4@TPBD-TPA was developed for the efficient determination of four types of aflatoxins in food samples (maize, maize oil, peanut, and peanut oil). The determination coefficients (R2) were ≥0.9972. The method exhibited detection limits ranging from 0.01 to 0.06 μg/kg and spiked recoveries of 80.0 to 113.1%. The intra-day and inter-day precision were less than 6.77%, indicating good repeatability. The adsorbent showed promising prospects for the efficient enrichment of trace amounts of aflatoxins in complex food matrices. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys are the lightest metal structural material for engineering applications and therefore have a wide market of applications. However, compared to steel and aluminum alloys, Mg alloys have lower mechanical properties, which greatly limits their application. Extrusion is one of the most important processing methods for Mg and its alloys. However, the effect of such a heterogeneous microstructure achieved at low temperatures on the mechanical properties is lacking investigation. In this work, commercial AZ80 alloys with different initial microstructures (as-cast and as-homogenized) were selected and extruded at a low extrusion temperature of 220 °C and a low extrusion ratio of 4. The microstructure and mechanical properties of the two extruded AZ80 alloys were investigated. The results show that homogenized-extruded (HE) sample exhibits higher strength than the cast-extruded (CE) sample, which is mainly attributed to the high number density of fine dynamic precipitates and the high fraction of recrystallized ultrafine grains. Compared to the coarse compounds existing in CE sample, the fine dynamical precipitates of Mg17(Al, Zn)12 form in the HE sample can effectively promote the dynamical recrystallization during extrusion, while they exhibit a similar effect on the size and orientation of the recrystallized grains. These results can facilitate the designing of high-strength wrought magnesium alloys by rational microstructure construction. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional simulation has been performed to investigate the potential consequences of flammable vapor explosion in a tunnel with an obstacle, the obstacle with different area blockage ratios (10, 20, 30 and 40%). The blast wave shape, increase in the maximum explosion overpressure, and the arrival time of peak pressure in the vicinity of the obstacle with different blockage ratios have been characterized. The simulation results show that the configuration of the blast wave was remarkably compressed due to the effects of obstacle and the deformation process which can be divided into four stages. The influence of blockage ratio on the maximum overpressure and the arrival time of peak pressure were mainly reflected in the back of the obstacle 1 m from the ground, and the maximum overpressure for this location decreases as the blockage ratio increases. Meanwhile, the maximum overpressure of 10% blockage ratio is 57% higher than that of 40% blockage ratio for the location of the back of obstacle. The arrival time of peak pressures for the location of the back of obstacle is delayed as the blockage ratio increases. The maximum overpressure under the tunnel ceiling showed an opposite trend between the location of the front of the obstacle and the location behind the obstacle. In the front of the obstacle, the maximum overpressure under the tunnel ceiling increases as the blockage ratio increases; however, it decreases as the blockage ratio increases in the back of the obstacle. What's more, the comparison of this paper's data and the results from available are published. It was found that the simulation results in this article are consistent with the experimental results of studies. [ABSTRACT FROM AUTHOR]

Background and aims: Cytokinins are known to negatively regulate plant root development and phosphorus (P) starvation responses. In this study, two Brassica napus root mutants insensitive to exogenous cytokinin, prl1 (a mutant with an elongated primary root) and lrn1 (a mutant with more lateral roots), were identified and used to evaluate P efficiency, alongside wild type (WT) plants. Methods: Solution and pot culture, RNA isolation, RT-PCR were used. Results: lrn1 produced the highest shoot dry weight (SDW) and root dry weight (RDW) among the three genotypes at both low P (LP) and high P (HP) conditions. prl1 had higher SDW at both P conditions, and higher RDW at LP, in contrast to WT plants. lrn1 not only accumulated more P from the culture medium but utilized it effectively in shoot growth, whilst prl1 just showed higher P use efficiency compared to WT at LP. Trans-zeatin riboside (tZR) and isopentenyl adenosine (iPA) concentration in lrn1 roots were both significantly lower than that in WT roots at both P conditions. Root iPA concentration in prl1 was lower than that in WT under both P conditions, however, root tZR concentration was greater in prl1 than WT under LP condition. Transcription of the P starvation induced genes BnSPX3;1 and BnSPX3;2 were up-regulated in the roots of mutants under both P conditions. Conclusions: These results suggested that an improved root system might be associated with the reduced cytokinin concentration and lead to a significant increase in acquisition and utilization of P nutrient for lrn1. [ABSTRACT FROM AUTHOR]

The design of epoxy resin (EP) with high flame retardancy, smoke suppression, and rapid curing capability has attracted significant attention in industrial applications. To reduce the fire hazard and enhance the processability of EP-based materials, a novel hybrid (g-C3N4@NiPS) was synthesized by in-situ growth of flower-like nickel phyllosilicate on the surface of graphite phase carbon nitride. The effects of g-C3N4@NiPS on the thermal stability and combustion properties of EP composites were investigated. The results showed that 5 mass% g-C3N4@NiPS delayed the early-stage decomposition and increased the residual char of the EP composite from 11.3 to 20.8 mass%. The addition of 5 mass% g-C3N4@NiPS reduced the peak heat release rate and peak smoke production rate of the EP composite by 34.5% and 41.9%, respectively. Specifically, the maximum release rates of CO and CO2 decreased by 49.2% and 32.3%, respectively, greatly reducing the fire hazard. The residual char of EP/g-C3N4@NiPS exhibited a high degree of graphitization and displayed an excellent barrier effect, reducing the supply of fuel and the release of toxic fumes during EP combustion. Additionally, the presence of g-C3N4@NiPS showed a beneficial impact on expediting the cure response. This study provides a feasible strategy for the wide application of EP.Graphical abstract: The design of epoxy resin (EP) with high flame retardancy, smoke suppression, and rapid curing capability has attracted significant attention in industrial applications. To reduce the fire hazard and enhance the processability of EP-based materials, a novel hybrid (g-C3N4@NiPS) was synthesized by in-situ growth of flower-like nickel phyllosilicate on the surface of graphite phase carbon nitride. The effects of g-C3N4@NiPS on the thermal stability and combustion properties of EP composites were investigated. The results showed that 5 mass% g-C3N4@NiPS delayed the early-stage decomposition and increased the residual char of the EP composite from 11.3 to 20.8 mass%. The addition of 5 mass% g-C3N4@NiPS reduced the peak heat release rate and peak smoke production rate of the EP composite by 34.5% and 41.9%, respectively. Specifically, the maximum release rates of CO and CO2 decreased by 49.2% and 32.3%, respectively, greatly reducing the fire hazard. The residual char of EP/g-C3N4@NiPS exhibited a high degree of graphitization and displayed an excellent barrier effect, reducing the supply of fuel and the release of toxic fumes during EP combustion. Additionally, the presence of g-C3N4@NiPS showed a beneficial impact on expediting the cure response. This study provides a feasible strategy for the wide application of EP. [ABSTRACT FROM AUTHOR]