混合材对碱—碳酸盐反应的影响

利用快速测长法研究了混合材对碱—碳酸盐反应的影响。通过试验证明混合材能减缓碱—碳酸盐反应的速度,但不能有效地抑制碱—碳酸盐反应,并初步探讨了混合材不能有效地抑制碱—碳酸盐反应的机理。     

Guerbet十四醇的合成与表征

以正庚醇为原料 ,通过Guerbet反应合成Guerbet十四醇 (2 戊基壬醇 ,C14 GA)。用IR、NMR和元素分析测定了C14 GA的结构 ,并研究了反应温度和用料比对其产率的影响。实验结果如下 :(1)在较优化的反应条件下 (正庚醇的总加入量为 1mol,在实验过程中 ,先加入 1/ 3mol庚醇和 1/ 4mol的KOH ,在 16 0℃下反应 2h ,然后再加入剩下的 2 / 3mol庚醇和 4g 5 %Pd -C催化剂 ,在 15 5℃下反应 6h)合成产物 ,其产率可达到 5 4 2 0 % ;(2 )所合成的产物与试图要得到的Guerbet十四醇 (2 戊基壬醇 ,C14 GA)含有相同的基团 (2×—CH3、10×—CH2 —、1×CH、1×—CH2 —O—和 1×—OH) ,而且 ,所合成的产物中 ,w (C) =79 0 6 % ,w (H ) =13 6 2 % ,与从Guerbet十四醇分子式计算的理论值w(C) =78 5 0 % ,w (H) =14 0 1%基本一致。可见所合成的产物正是Guerbet十四醇 (C14 GA)     

Reaction products of ammonium nitrate phosphate fertilizers of varying water-soluble phosphorus content in different Indian soils

Studies were undertaken on the isolation and identification of reaction products of ammonium nitrate phosphate (ANP) fertilizers containing 30, 50 and 70 per cent water-soluble phosphorus (WSP) of total phosphorus in representative soils of the vertisol, oxisol, alfisol, entisol, mollisol and aridisol groups of India. ANP fertilizers were applied in solid form to soil, and reaction products formed at and around the site of ANP fertilizer placement were identified after six weeks incubation in moist soils by X-ray diffraction technique. DCPD (dicalcium phosphate dihydrate- CaHPO₄ · 2H₂O) was the major reaction product of ANP fertilizers containing 30 and 50 per cent WSP in vertisol, entisol, aridisol, mollisol, oxisol and alfisol, and of ANP containing 70 per cent WSP in vertisol, entisol, alfisol, aridisol and mollisol. DCP (dicalcium phosphate-CaHPO₄) was detected with ANP of 30 and 50 per cent WSP in the vertisol, alfisol, entisol, mollisol and aridisol groups of soils. In addition to DCPD, FePO₄ · 2H₂O (metastrengite) and AlPO₄ · 2H₂ O-monoclinic (metavariscite) were formed in alfisol and oxisol soils with ANP of 30 and 50 per cent WSP. FePO₄ · 2H₂O and AlPO₄ · 2H₂O (metavariscite) were identified in alfisol and oxisol soils while AlPO₄ · 2H₂O-orthorhombic (variscite) was formed in alfisol soils with ANP of 70 per cent WSP.     

一种无线传感器网络链式传输分簇路由协议

由于周围环境对无线传感器网络(WSNs)的影响,在布设到特殊环境下时会产生信号的衰减与损耗,导致通信不畅。针对此问题,提出一种以LEACH路由协议为基础适应特殊环境(长直空间)的新型路由算法。本算法采用链式传输,即从内部逐一将信号传输给距空间最外端且距基站位置较近的簇头,克服了内部节点死亡过快的问题。同时簇内采用链式传输并且改进簇头阈值与成簇半径,减小了能量消耗,提高了稳定性,克服了LEACH算法的不足。     

Polyesterification and isomerization of maleic anhydride and 1,6-hexane diol as studied by 1H and 13C n.m.r.

The polyesterification and isomerization reaction of 1,6-hexane diol and maleic anydride in a melt without catalyst was studied by ¹³C and ¹H n.m.r. spectroscopy. The structure and concentration of oligoester species during the polyesterification and isomerization were determined depending on the reaction temperature and time. According to the number and configuration of repeating units determined from ¹H n.m.r. spectra kinetics of both reactions were also considered. The degree of isomerization is continuously increasing in the investigated reaction range.     

甲酸甲酯合成与转化的催化技术

本文评述了甲酸甲酯(MF)合成与转化的催化技术,展示了从MF出发发展C_1化学的可能途径,在MF的合成方面详细地分析了从甲醇出发的羰化法、脱氢法和氧化法催化技术,简介了我们的有关研究工作。     

Exploring single electrode reactions in polymer electrolyte fuel cells

Utilising a pseudo-reference electrode in polymer electrolyte fuel cells allows for the separation of anodic and cathodic contributions to the entire cell impedance. Modelling the impedance responses by using equivalent circuits inhibits the investigation of kinetic parameters of the basic electrochemical reactions, which take place at single electrode-electrolyte interfaces. Therefore, we evaluate single electrode impedance measurements by a kinetic model, which is based on specific reaction pathways, either for the oxygen reduction reaction (ORR) or the hydrogen oxidation reaction (HOR). As a consequence, it is possible to obtain kinetic parameters for the specific reaction of interest. Furthermore, the information gained from the single electrode impedance measurements and the kinetic model can give insight into single reactions steps. In particular, the ORR has to include a chemical step in the reaction pathway.     

喷动床反应模型的研究进展

喷动床是一种可实现热量重复循环的高效反应器 .介绍了目前喷动床研究中出现的各种反应模型 ,从等温和非等温两个方面讨论了一维轴向、流管、半分割和流动反应耦合等各类模型的基本思想和理论及各自的特点 ,并提出了进一步发展的方向 .     

Reaction pathways of ethane oxidative and non-oxidative dehydrogenation on γ-Al2O3 studied by temperature-programmed reaction (TP-reaction)

In this work, the reactions of ethane and ethene in an oxidizing and non-oxidizing atmosphere over γ-alumina were investigated under temperature-programmed conditions, in an attempt to estimate the possible contribution and functionality of the support in the reaction pathway of ethane ODH over MoO₃/Al₂O₃ catalysts. The results indicate that alumina contributes to the primary deep oxidation and dehydrogenation routes of ethane to CO_x and coke respectively, which proceed effectively over the acidic OH groups and the Al³⁺–O²⁻ acidic centers. On the contrary, the formation of ethylene seems to be coupled to the presence of redox sites on the catalytic surface and requires the presence of the molybdena phase. Moreover, the redox sites of the MoO_x species were found to unselectively activate the further overoxidation of the olefin to carbon oxides. Therefore, Al₂O₃ catalyzes the unselective primary oxidation of ethane to carbon oxides, whereas the molybdena phase is involved in the selective oxidative dehydrogenation (ODH) of ethane to ethene and the secondary overoxidation of ethene to CO_x.     

Prediction model of compressive strength development of fly-ash concrete

Based on experimental results concerning the compressive strength development of concrete containing fly ash, the authors derived an estimation equation for compressive strength development. The equation can express coefficient , which indicates the activity of fly ash as a binder, in the form of a function of age, fly-ash content, and Blaine specific surface area of fly ash.

This equation is capable of explaining the increases in the early strength due to fly ash in place of part of fine aggregate, the decreases in the early strength due to fly ash in place of part of cement, the increases in the long-term strength due to pozzolanic reaction, the relationship between the fly-ash replacement ratio and the ratio of strength increase/decrease, and the effect of fly ash's Blaine specific surface area on the strength.