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The smoke suppression of rigid polyurethane foam (RPUF) modified by melamine was investigated based on three sections: the condensed phase, the carbon layer, and the gas phase. In the condensed phase, the results of thermogravimetry, X‐ray photoelectron spectroscopy (XPS) N1S spectrum, and Fourier transform infrared spectroscopy indicated that melamine could suppress the degradation of RPUF by reacting with the aromatic hydrocarbons. It also reduced the smoke generation because the volatilizable aromatic hydrocarbons were the principal smoke precursors in a fire. In the carbon layer, the decrease from 38.50% to 24.76% of the inner layer oxygen content identified by XPS full‐spectrum and C1S spectrum indicated that melamine could prevent oxygen from transferring into the inner foam by the formation of an enhanced surface carbon layer, and the enhanced carbon layer could also block the release of smoke precursors. In the gas phase, the content of total aromatic hydrocarbons declined to 59.12% according to pyrolysis gaseous chromatography mass spectroscopy and indicated that melamine could reduce the smoke precursors. The results of smoke density chamber and cone calorimeter tests revealed that the addition of the melamine could decrease the smoke density of burning RPUF. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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场激活加压燃烧合成WC-Ni复合材料的工艺参数研究 总被引:1,自引:0,他引:1
以钨、碳和镍为原料,在电场激活下,材料的燃烧合成和致密化同时进行,短时间内完成了碳化钨镍复合材料的制备。研究了场激活 加压燃烧合成中的工艺参数,如脉冲电流、能量控制模式、升温速率、最高温度和压力对反应的影响。测量了在反应合成和致密化前后的样品 收缩率。所制备的复合材料的相对密度,490N载荷下Vickers硬度和断裂韧性分别为99.2%,13.965GPa和5.9MP·m1/2。 相似文献
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Mengyi Chen Xiaoyang Zhu Xiaojuan Liu Caiyu Wu Canye Yu Guojian Hu Lin Chen Riyuan Chen Mondher Bouzayen Mohammed Zouine Yanwei Hao 《International journal of molecular sciences》2021,22(7)
Auxin response factors (ARFs) play important roles in various plant physiological processes; however, knowledge of the exact role of ARFs in plant responses to water deficit is limited. In this study, SlARF4, a member of the ARF family, was functionally characterized under water deficit. Real-time fluorescence quantitative polymerase chain reaction (PCR) and β-glucuronidase (GUS) staining showed that water deficit and abscisic acid (ABA) treatment reduced the expression of SlARF4. SlARF4 was expressed in the vascular bundles and guard cells of tomato stomata. Loss of function of SlARF4 (arf4) by using Clustered Regularly Interspaced Short Palindromic Repeats/Cas 9 (CRISPR/Cas 9) technology enhanced plant resistance to water stress and rehydration ability. The arf4 mutant plants exhibited curly leaves and a thick stem. Malondialdehyde content was significantly lower in arf4 mutants than in wildtype plants under water stress; furthermore, arf4 mutants showed higher content of antioxidant substances, superoxide dismutase, actual photochemical efficiency of photosystem II (PSII), and catalase activities. Stomatal and vascular bundle morphology was changed in arf4 mutants. We identified 628 differentially expressed genes specifically expressed under water deficit in arf4 mutants; six of these genes, including ABA signaling pathway-related genes, were differentially expressed between the wildtype and arf4 mutants under water deficit and unlimited water supply. Auxin responsive element (AuxRE) elements were found in these genes’ promoters indicating that SlARF4 participates in ABA signaling pathways by regulating the expression of SlABI5/ABF and SCL3, thereby influencing stomatal morphology and vascular bundle development and ultimately improving plant resistance to water deficit. 相似文献
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Nanocrystalline Ni3Al was fabricated through mechanical alloying of elemental powders and spark plasma sintering. The nanocrystalline Ni3Al has a nearly full density after being sintered at 1223 K for 10 min under a pressure of 65 MPa. Isothermal and cyclic oxidations of nanocrystalline Ni3Al were tested at 1173–1373 K with intervals of 100 K. The results indicate that nanocrystalline Ni3Al exhibits excellent isothermal and cyclical oxidation resistance. The oxide scales consist primarily of dense and continuous -Al2O3. The grain refinement is beneficial for improving the oxidation resistance of Ni3Al by providing more nucleation centers for the Al2O3 formation, promoting the selective formation of Al2O3 and improving the adhesion of oxide scales to the matrix. 相似文献
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李国建 《锻压装备与制造技术》2003,38(4):23-24
介绍了快速制动双绕组电动机的结构原理、性能特点,选用该电动机应注意的一些问题及其在压力机上的应用。 相似文献
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在役门座式起重机应力测试技术探讨 总被引:1,自引:0,他引:1
为保证港口在役大型门座起重机长期运行的安全,对其金属结构在不同载荷条件下承载能力的定期评价工作就显得非常必要。本文对某港口一台使用了25年,型号为MQ1030门座起重机主金属结构采用现场应变电测技术进行测试,并经相应的数据处理转化为应力,通过对5个典型工况的综合测试,得出该起重机主金属结构最大动应力为136.34MPa,并对金属结构损伤和承载能力进行了较为全面地评价。本次应变电测数据还为该机后期的典型载荷编制和疲劳寿命计算提供参考依据。 相似文献
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