Although we demonstrated good correlation and high discriminative power of the BIS-Vista monitor in depicting a MCBFV decline that could serve as indicator of decline in cerebral activity, BIS-Vista cannot be considered a reliable indicator of cerebral ischemia/hypoperfusion that could replace transcranial Doppler monitoring to determine whether a shunt is to be placed.
In order to study the inhibition effect of gas-solid two-phase inhibitors on a methane explosion, the influence of these parameters was investigated and compared with that of single-phase inhibitors. The results show that the inhibition effect of gas-solid two-phase inhibitors on a methane explosion is better than the added effect of two single-phase inhibitors, indicating that a synergistic effect can be obtained by gas-solid two-phase inhibitors. The two-phase inhibitors which are composed of NaHCO 3 (BC) powders and inert gas have a better suppressing property than those composed of NH 4 H 2 PO 4 (ABC) powders and inert gas. The two-phase inhibitors composed of CO 2 and powders have a better suppressing property than those composed of N 2 and powders. The 9.5% premixed methane-air mixture can be completely inhibited by 0.10 g/L BC powders mixed with 8% CO 2 . The suppression mechanisms of the gas-solid two-phase inhibitors on the methane explosion were discussed.Energies 2019, 12, 398 2 of 10 Chemical powders, such as carbonate, phosphate, halide etc., have widely been used as extinguishing agents on methane explosions and dust explosions, due to their physical and chemical inhibition effects. The inhibition effects of various chemical powders (such as SiO 2 , CaCO 3 , ABC, BC, zeolite, red mud, Al(OH) 3 , composite powders, etc.) on methane explosions have been studied [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The experimental results presented that different powders showed different suppression performances on methane explosions.Recently, more attentions have been paid to gas-solid two-phase inhibitors [27][28][29]. Deng [30] studied the influence of a two-phase inhibitor Mg(OH) 2 /CO 2 on methane explosion, and observed that the actual superposition effect was inferior to the theoretical superposition effect. The research by Luo [31] showed that the ABC/CO 2 two-phase inhibitor had a cooperative synergism, which gave a good suppression performance on methane explosion. Jiang [32] researched the suppression effect of ultrafine ABC powders and N 2 mixture on methane explosions. The results showed that the maximum decreasing amplitudes of the overpressure and the flame speed were 76.8% and 100%, respectively. According to the research, it is clear that the suppression effect of gas-solid two-phase inhibitors was better than the single-phase gases or powders. However, there are few studies comparing the actual suppression effect of gas-solid two-phase inhibitors with the theoretical addition effect suppressed by single-phase gas and powders, respectively. It is not clear whether there is a cooperative effect between inert gas and powders.In this paper, the influence of ABC powders (NH 4 H 2 PO 4 ), BC powders (NaHCO 3 ), N 2 , CO 2 and gas-solid two-phase inhibitors on the 9.5% premixed methane-air explosion parameters, including the max-pressure, the time to max-pressure and the maximum rate of pressure rise, was experimentally researched using a 20 L spherical vessel. The actual suppre...
The composite powders composed of red mud (RM) and NH4H2PO4 (NH4H2PO4/RM) were successfully prepared by the anti-solvent method. The composition and structure of the NH4H2PO4/RM composite powders were characterized by the techniques of X-ray diffraction (XRD), SEM, N2 adsorption-desorption and Thermogravimetry-Differential scanning calorimetry (TG-DSC). The analysis results indicate that the as-prepared samples are composed with uniform nanoparticles and possess the porous structure. The methane explosion suppression characteristics of the NH4H2PO4/RM composite powders were tested by a 20 L spherical explosion system and a 5 L pipe test system. The results show that the NH4H2PO4/RM composite powders possess considerable suppression properties on methane explosion. When the loading content of NH4H2PO4 reached 30%, the maximum pressure and the maximum pressure rise rate of methane explosion were decreased by 35.1% and 95.8%, respectively. When comparing with no powder addition, the time to reach the pressure peak was extended from 0.07 s to 0.50 s. The NH4H2PO4/RM composite powders presented a synergistic suppression effect between NH4H2PO4 and RM, which made it exhibit considerable suppression property than that of pure NH4H2PO4 or red mud powders.
We added an organic additive 2-amino-2-methyl-1-propanol (AMP) and water to dimethylformamide (DMF) and exfoliated graphite therein to prepare graphene. When the content of AMP was 1.0 vol % and the content of water was 0.4 vol %, the dispersion of graphene was obtained at the concentration up to 0.3 mg mL−1, which was 50% higher than that obtained by directly exfoliating graphite in DMF for 24 h. At the same time, the graphene sheets maintained high quality with little impurity.
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