Mechanism of mechanical–chemical synergistic activation for preparation of mullite ceramics from high-alumina coal fly ash

High-alumina coal fly ash (HAFA) is a special solid waste due to the existence of more than 45% alumina and 35% silica, which can be applied to prepare Al-Si series ceramics if the impurities can be removed and the Al/Si mass ratio can exceed 2.55 (Mullite: 3Al₂O₃.2SiO₂). In this work, a new mechanical–chemical synergistic activation–desilication process is proposed, and the contents of different impurities can be lowered up to less than 1%, and the Al/Si mass ratio can be elevated from 1.26 to 2.71. Especially, the mechanism of this process is investigated in detail. The analysis of the mechanism shows that the decrease of Q⁴(3Al) and the increase of Q⁴(0Al), Q⁴(1Al), and Q⁴(2Al) improve amorphous silicate reactivity through synergistic activation, and the exposed amorphous Si-O-/Si-O-Si can be removed by OH- during the desilication process (desilicated ratio>55%), which help the fine mullite to exhibit excellent properties (bulk density > 2.85 g/cm³, apparent porosity < 0.5%) during the sintering process. Finally, this process not only decreases the pollution but also alleviates the shortage of Al/Si resources and promotes the clean development of coal-fired power generation.     

Crystallographically oriented W-type barium hexaferrite BaZn2Fe16−xScxO27 with high squareness ratio

A series of oriented W-type barium hexaferrites of composition BaZn₂Fe_16?xSc_xO₂₇ (where x?=?0, 0.1, 0.2, 0.3, 0.4) has been synthesized by conventional ceramic methods and characterized by XRD, SEM, EDS, FTIR, and VSM. In this work, the effect of trivalent Sc substitution for trivalent Fe on the structure and magnetic properties of Zn₂W has been studied. The XRD results showed that all the specimens consisted of single phase of W-type ferrites. EDS analysis confirmed that the content of Ba, Zn, Sc, and Fe were closed to the elemental composition of BaZn₂Fe_16?xSc_xO₂₇. The SEM revealed the hexagonal platelet-like structure of the BaZn₂Fe_16?xSc_xO₂₇ and the average grain sizes of all samples remain in the range of single domain dimension (0.5 µm?~?1 µm). The SEM also demonstrated that the samples maintained high crystallographic c-axis texture when Sc³⁺ content was less than 0.4. The SEM results were consistent with magnetic hysteresis loops. As the function of Sc substitution, the squareness ratio (M_r/M_s) ranged from 0.78 to 0.82, which was critical for self-biased application. Moreover, the magnetocrystalline anisotropy field (H_a) decreased. The saturation magnetization (M_s) increased from 53.61 to 54.04 emu/g as x increased from 0 to 0.1, and then it decreased to 46.50 when x > 0.1. The samples showed other excellent magnetic properties, such as appropriate anisotropy field (~?9 kOe),and high coercive fields (~?1300 Oe). Therefore, the prepared Zn₂W ferrites are suitable candidate for the microwave devices operated at low frequency.

     

Calycosin Suppresses RANKL-Mediated Osteoclastogenesis through Inhibition of MAPKs and NF-κB

Calycosin, an isoflavonoid phytoestrogen, isolated from Radix Astragali, was reported to possess anti-tumor, anti-inflammation, and osteogenic properties, but its impact on osteoclast differentiation remains unclear. In this study, we examined the effects of calycosin on osteoclastogenesis induced by RANKL. The results showed that calycosin significantly inhibited RANKL-induced osteoclast formation from primary bone marrow macrophages (BMMs). Calycosin also dose-dependently suppressed the formation of bone resorption pits by mature osteoclasts. In addition, the expression of osteoclatogenesis-related genes, including cathepsin K (CtsK), tartrate-resistant acid phosphatase (TRAP), and MMP-9, was significantly inhibited by calycosin. Furthermore, the results indicated that calycosin down-regulated the expression levels of NFATc1 and c-Fos through suppressing the activation of NF-κB and MAPKs. Our results indicate that calycosin has an inhibitory role in the bone loss by preventing osteoclast formation, as well as its bone resorptive activity. Therefore, calycosin may be useful as a therapeutic reagent for bone loss-associated diseases.     

围岩松动理论指导井巷维修实践

1概况
　　新洛公司山西煤矿主采煤层23＃、21＃、13＃煤层，其中23＃煤层为厚煤层，平均厚度5.0 m ，煤层结构复杂，含多层薄层夹矸，普氏硬度3～4，煤层倾角8°～22°，煤层赋存相对稳定。23＃煤层伪顶为粉砂岩夹煤线，厚度0.8 m ，含炭质较高；直接顶为粗粉砂岩，厚度2.0m，致密坚硬；老顶为灰色细砂岩，厚度15 m ，坚硬。直接底为粉砂岩，厚度2.0m ，较坚硬，不易底鼓；老底为灰色细砂岩，厚度5m ，致密坚硬。该矿为瓦斯矿井，23＃煤层瓦斯绝对涌出量为3.17 m3／min ，相对涌出量6.28 m3／t ，煤层不易自燃，煤尘无爆炸性。     

装配式木框架结构消能节点拟静力试验研究

消能节点装配式木框架结构体系是以Q235钢制成的消能节点将规格木材制成的梁、柱连接成具有较大抗侧刚度的延性框架体系.通过3个足尺消能节点的拟静力试验,研究了该节点的受力性能、破坏形态、滞回特性与耗能能力等.研究结果表明:在弹性工作阶段,消能节点将木梁、柱连接成具有较大抗侧刚度的框架体系;在非线性工作阶段,结构通过节点的...     

高原低氧对大鼠海马MDA及其Ca2+-ATP酶活性的影响及其机制

目的 初步探讨高原低氧对大鼠海马MDA及其Ca2+-ATP酶活性影响其机制.方法 将48只Wistar大鼠随机分为2组,在不同海拔喂养30天后,应用比色法测定海马组织MDA含量;使用定磷比色法测定Ca2+-ATP酶活性.结果 高原组大鼠海马MDA含量明显高于低海拔对照组,而Ca2+-ATP酶活性显著降低;结论高原低氧大鼠海马MDA含量增加,Ca2+-ATP酶功能降低.     

氡对大鼠BALF细胞基因甲基化和血清肿瘤标志物的影响

研究不同剂量氡暴露对大鼠基因甲基化和血清肿瘤标志物影响,探讨其在氡致肺癌早期诊断中的价值和意义.以HD-3型多功能生态氡室模拟不同浓度氡及其子体水平,30只染氡大鼠随机分为5组,即对照组、30工作水平月(WLM)组、60 WLM组、90 WLM组、120 WLM组,每组6只;用甲基化特异性PCR (MSP)方法,检测各...     

三孔干涉条件下部分相干电磁光束的偏振特性

推导了三孔干涉条件下的交叉谱密度矩阵,研究了该条件下部分相干光偏振特性的变化情况。比较了x、y方向场分量不相关和相关的情况,并与同样条件下双孔干涉的偏振度变化进行了对比。研究表明,偏振度在观察面上是振荡变化的,离中心越远振荡越剧烈;不同位置的偏振度传输足够长的距离后都将趋于稳定,其稳定值与参量Bxy和δxy有关,且离中心越远其偏振度达到稳定的传输距离越长;轴上偏振度与三孔的初始相干度是密切相关的。特别指出,当x、y方向场分量相关时,对应点偏振度的值远远大于其不相关的情况。     

一种可变电压等级恒功率输出的变流器实现方法

高压大功率变流器已得到广泛应用,但目前,变流器在输出电压降低时输出功率也等比的减少,只能是运用多个变频器来实现恒功率输出。本文介绍了采用IGBT多个功率单元（H桥）串联相结合的多种变换形式,达到恒功率输出多种电压等级的目的。通过组合开关切换实现了1 3.2kV、6.6kV、3.3kV、1.65kV和0～1000V直流的...     

内通道气帘的设计与分析

保持光传输通道内单一均匀的低吸收系数气体,对削弱内通道中的气体热效应有重要意义。采用气帘作为封装设备,对气帘的结构进行了设计。取气帘入口气体为氮气,出口气体为空气,借助现有计算流体力学软件FLUENT提供的组分输运模型,对气帘进行了数值模拟。结果表明,气帘入口段形成的平面射流可以阻挡外界空气的回流;在氮气与氧气相混合的区域内,尽管气体密度存在一定起伏,但气体密度变化的梯度方向与光传输方向基本是平行的,这种密度起伏只会对光场相位的活塞项产生影响,不会影响激光的远距离传输。最后,对气帘的性能进行了实验测试,实验结果表明,设计的气帘能够对管道内的气体进行密封,并避免了较大光程差的引入。