延龄草苷的合成方法研究

延龄草苷为薯蓣皂苷元-3-O-β-D-吡喃葡萄糖苷,来源于中药延龄草,为甾体皂苷类化合物,具有广泛的生物活性.通过两种方法合成延龄草苷:Koenigs-Knorr法,以溴代糖为糖基供体,以碳酸银作为催化剂,将薯蓣皂苷元与溴代-α-D-四乙酰葡萄糖成苷合成延龄草苷;三氟化硼-乙醚催化法,全乙酰葡萄糖作为糖供体,将薯蓣皂苷...     

沼渣生物炭在水处理中的应用进展

以沼渣为原料制备生物炭是实现沼渣安全处置和资源化利用的有效途径之一.沼渣经过厌氧消化处理,在一定程度上优化了沼渣生物炭的组分结构和物化特性,因而沼渣生物炭具有低成本、来源广、吸附及催化性能好等特点被应用于去除水中污染物.该文对当前沼渣生物炭的原料来源、制备及改性方法进行了总结,归纳了沼渣生物炭作为吸附剂和碳基催化剂在水...     

软启动器在氯气压缩机中的应用

比较了低压鼠笼型电动机的直接启动方式、Y-△降压启动方式和晶闸管软启动器的启动方式,介绍了软启动器在氯气压缩机启动过程中的启动方法、设置及其维护。     

聚氨酯橡胶弹性体及树脂的市场优势与技术新进展

介绍聚氨酯材料种类．重点阐述聚氨酯橡胶弹性体性能、应用领域及应用技术新进展,并介绍了聚氨酯树脂汽车轮胎代替橡胶轮胎的前景。     

30%草甘膦水剂的配方研究

对几种表面活性剂在30%草甘膦水剂中的应用进行了筛选和相关性能的研究,最佳配方为草甘膦原粉30%、氨水4.0%～5.0%、AOS（α-烯基磺酸钠）4.0%、APG（烷基糖苷）6.0%、茶皂素0.50%、有机硅消泡剂0.10%~0.50%。其表面张力、起泡性、泡沫稳定性、黏度、常温热贮稳定性指标均表现优异,符合草甘膦水剂的质量标准。     

聚甲基丙烯酰亚胺泡沫塑料的制备及研究现状

以丙烯腈(AN)、-甲基丙烯酸(MAA)为主要单体原料,以丙烯酰胺(AM)为第三共聚单体,加入引发剂、发泡剂等自由基本体聚合制得AN-MAA-AM共聚物,然后在高温下将AN-MAA-AM共聚物进行高温发泡得到聚甲基丙烯酰亚胺(PMI)泡沫塑料。详细介绍了PMI泡沫塑料的制备和研究现状,并对PMI泡沫塑料的研究方向进行了展望。     

Development of Potent Adenosine Monophosphate Activated Protein Kinase (AMPK) Activators

Previously, we reported the identification of a thiazolidinedione‐based adenosine monophosphate activated protein kinase (AMPK) activator, compound 1 (N‐[4‐({3‐[(1‐methylcyclohexyl)methyl]‐2,4‐dioxothiazolidin‐5‐ylidene}methyl)phenyl]‐4‐nitro‐3‐(trifluoromethyl)benzenesulfonamide), which provided a proof of concept to delineate the intricate role of AMPK in regulating oncogenic signaling pathways associated with cell proliferation and epithelial–mesenchymal transition (EMT) in cancer cells. In this study, we used 1 as a scaffold to conduct lead optimization, which generated a series of derivatives. Analysis of the antiproliferative and AMPK‐activating activities of individual derivatives revealed a distinct structure–activity relationship and identified 59 (N‐(3‐nitrophenyl)‐N′‐{4‐[(3‐{[3,5‐bis(trifluoromethyl)phenyl]methyl}‐2,4‐dioxothiazolidin‐5‐ylidene)methyl]phenyl}urea) as the optimal agent. Relative to 1 , compound 59 exhibits multifold higher potency in upregulating AMPK phosphorylation in various cell lines irrespective of their liver kinase B1 (LKB1) functional status, accompanied by parallel changes in the phosphorylation/expression levels of p70S6K, Akt, Foxo3a, and EMT‐associated markers. Consistent with its predicted activity against tumors with activated Akt status, orally administered 59 was efficacious in suppressing the growth of phosphatase and tensin homologue (PTEN)‐null PC‐3 xenograft tumors in nude mice. Together, these findings suggest that 59 has clinical value in therapeutic strategies for PTEN‐negative cancer and warrants continued investigation in this regard.     

微晶β-SiAlON材料的制备

以原料配比(w):硅粉39.4%、金属铝粉12.7%、氧化铝粉47.9%为基础配方进行配料,分别经1 300、1 350、1 400、1 450、1 500℃保温3 h或5 h氮化反应制备β-SiAlON材料。研究了Fe2O3烧结助剂、煅烧温度和保温时间对制备β-SiAlON材料的体积密度、耐压强度、物相组成和显微结构的影响。结果表明:添加2%(w)的Fe2O3,提高煅烧温度和延长保温时间,都有助于烧结的进行。添加2%(w)的Fe2O3作烧结助剂,在N2气氛中于1 500℃下保温5 h烧成试样的耐压强度达到85.44 MPa,体积密度达到2.92 g·cm-3,以β-SiAlON为主晶相,晶粒发育良好,呈棱柱状,直径大约1μm,长度大约2μm,且分布比较均匀。     

硫化时间对HNBR/ZMMA复合材料形态结构及性能的影响

采用炭黑和单甲基丙烯酸锌(ZMMA)并用作补强剂制备了氢化丁腈橡胶(HNBR)复合材料,使用X射线衍射法和透射电子显微镜法分析了ZMMA在HNBR硫化过程中的结构和形态变化,并研究了一段硫化时间对复合材料力学性能的影响。结果表明,在硫化过程中,ZMMA发生了复杂的化学反应;随着一段硫化时间的延长,氢化丁腈橡胶复合材料的拉伸强度和100%定伸应力变化都不大,而撕裂强度先增大后减小,拉断伸长率减小。X射线衍射结果表明,ZMMA由结晶态转变为非结晶态。透射电子显微镜分析结果表明,在硫化开始阶段,ZMMA聚合反应已经完成,有大量的纳米级粒子分布在橡胶基体中。     

Dynamics and scaling of explosion cratering in granular media

Granular cratering is a ubiquitous phenomenon occurring in various natural and industrial contexts. Although impact‐induced granular cratering has been extensively studied, fewer experiments have been conducted on granular cratering via low‐energy explosions. Here, we study the dynamics and scaling of explosion granular cratering by injecting short pulses of pressurized air in quasi‐two‐dimensional granular media. Through an analysis of the dynamics of explosion processes at different explosion pressures, explosion durations, and burial depths, we identify two regimes, the bubbling and the eruption regimes, in explosion granular cratering. Our experiments explore the distinctive dynamics and crater morphologies of these regimes and show the energy scaling of the size of explosion craters. We compare high‐energy and low‐energy explosion cratering as well as explosion and impact cratering in terms of their energy scalings. Our work illustrates complex granular flows in explosion cratering and provides new insights into the general scaling of granular cratering processes. © 2017 American Institute of Chemical Engineers AIChE J, 64: 2972–2981, 2018