To meet the commercial requirements of inorganic heat insulators,the mixture of diatomite and Ca(OH)2 are evenly dispersed,mold-compacted,and then hydrothermally solidified due to the formation of tobermorite under an autoclaved process.Systematic investigations of the preparation conditions(including mix ratio,autoclaved factors,mold pressure,etc)were carried out to optimize the serving properties of such tobermorite-based products.As a result,a compressive strength of more than 30 MPa was realized for the specimen in high density(about 1.30(g·cm-3)).On the contrary,the specimen in light weight for example 0.63(g·cm-3)typically showed a thermal conductivity of around 0.12(W·m-1·K-1).The present work developed a feasible way to produce and to control the serving properties of diatomite-based heat insulators by a process of hydrothermal solidification,in which the optimized value of Ca/Si ratio was proposed to be 0.6~0.7,while the water content is 25% in weight,and hydrothermal reaction is performed at 180 ℃ for no more than 24 hours.
TONG Yu1,GAO Jian1,XIA Feng1,XU Dawei2,SONG Lili3,YANG Wenrui1,ZENG You1(1.School of Materials Science and Engineering,Shenyang Jianzhu University,Shenyang,China,110168
目的:探讨血清淀粉样蛋白A转录激活因子(serum amyloid A-activating transcription factor,SAF)编码区外显子e4A和e4B区域的组蛋白表观遗传学信息,为进一步研究SAF自身的转录调控机制和该基因转录与前体mRNA剪接的关系奠定基础。方法:利用染色体免疫共沉淀实验(Ch IP)分析SAF基因编码区组蛋白修饰的变化。首先收集LPS刺激不同时间的THP-1细胞,终浓度为1%甲醛交联蛋白质和DNA,利用超声波将其染色体随机断裂成适当大小的片段,选用Ch IP级别兔多克隆抗组蛋白H3抗体、兔多克隆抗组蛋白H3K36三甲基化抗体、兔多克隆抗组蛋白H3K9单甲基化抗体和兔多克隆抗RNA聚合酶II CTD重复区5号丝氨酸磷酸化抗体实验,以富集得到的DNA样品为模板进行半定量PCR和定量q PCR分析。结果:LPS刺激作用下SAF基因编码区组蛋白H3富集信号减弱、外显子e4A区域单个核小体上H3K9单甲基化(H3K9me1)水平减弱、H3K36三甲基化(H3K36me3)修饰富集水平增加、RNA pol II CTD重复序列第5号丝氨酸磷酸化水平降低。结论:LPS刺激导致SAF基因编码区组蛋白H3离散,该区域核小体解散、凝聚的染色体重塑呈开放构象;含SAF编码区基因信息的DNA暴露,利于RNA pol II转录延伸。
Thermal conductivity (TC) of high density polyethylene/multiwall carbon nanotube (HDPE/MWCNT) composite films was measured by laser pulse method. It is found that the TC increased quickly with the increase of MWCNT fraction when the volume fraction of MWCNT was below 3.35%. However,as the volume fraction of MWCNT was over 3.35%,the increasing rate became slow. A new percolation model was proposed based on the effect of MWCNT network to simulate the TC of HDPE/MWCNT composite films. The simulation result was in good agreement the experimental data well. In addition,the relationship of TC with the increase of temperature was also discussed.
