On the rank-dependence of coal tar secondary reactions

The secondary reactions of volatile compounds, including coal tar and light gases, accounts for a great portion of soot formation and the subsequent heat release and pollutant emissions in the combustion zone. While coal primary pyrolysis has been extensively studied over the last few decades and several network pyrolysis models has been developed to describe this process, coal secondary pyrolysis is still not well understood. The Babcock and Wilcox Company has been investigating coal secondary pyrolysis in order to develop a comprehensive mechanism for inclusion in predictive computational fluid dynamics and coal combustion models. Supportive experiments were carried out in an entrained-flow reactor. Tar was extracted from the pyrolysis byproducts of seven coals of widely-distributed rank at temperatures ranging from 923 to 1473 K, and analyzed by ¹³C NMR. Tars formed from higher rank coals generally demonstrated higher sooting propensities. This rank-dependent sooting propensity is associated with tar’s chemical structure properties. With increased heat treatment severity, tar molecules lose a substantial amount of aliphatic attachments, and the average size of substitution per cluster decreases. Compared to tars formed from high-rank bituminous coals, those formed from low-rank sub-bituminous coals have a larger attachment portion, higher averaged substitution, and higher oxygen-containing functional groups. These differences contribute to the higher cracking propensity observed for low-rank coal tars.     

Synthesis and luminescence properties of red-emitting phosphors NaY0.87Eu0.13(WO4)1.2(MoO4)0.8

A series of NaY_1−yEu_y(WO₄)_2−x(MoO₄)_x (x=0−2 and y=0.06−0.15) phosphors have been prepared by a combustion route. X-ray powder diffraction, photoluminescence excitation and emission spectra were used to characterize the resulting samples. The excitation spectra of these phosphors show the strongest absorption at about 396 nm, which matches well with the commercially available n-UV-emitting GaN-based LED chip. Their emission spectra show an intense red emission at 616 nm due to the ⁵D₀→⁷F₂ electric dipole transition of Eu³⁺. As the Mo content increases, the intensity of the ⁵D₀→⁷F₂ emission of Eu³⁺ activated at wavelength of 396 nm increases and reaches a maximum when the relative ratio of Mo/W is 2:3. The intense red-emission of the tungstomolybdate phosphors at near-UV excitation suggests that the material is a potential candidate for white light emitting diode (WLEDs).     

Evidence for a biogenic, microorganismal origin of rock varnish from the Gangdese Belt of Tibet

In the present study we examined material from the Ashikule Basin of Tibet. Chemical analyses were performed by use of energy dispersive X-ray spectroscopy and electron probe microanalysis to clarify whether the varnish layers that had developed on the surface of the rhyolite are indeed composed of varnish bodies and silica glaze. Electron microscopic analyses revealed that the surface of the varnish is covered both by filamentous hyphae bacterial and cocci-shaped forms. Within the varnish mineral layer in those samples two forms of bacteria-like microorganisms exist; cocci as tightly packed bacterial aggregates [within varnish bodies], and bacillus-like microorganisms [within the varnish matrix, that surrounds the varnish bodies]. The bacillus-like forms are embedded in a network of filaments that have diameters between 35 and 45 nm. These bacilli with the surrounding filaments are assumed to have been involved in biofilm formation (synthesis of extracellular polymeric substances) prior to their live burial. We concluded that the formation of the varnish layers was for the most part biogenically driven by microorganisms.     

新型罗丹明B席夫碱荧光探针的光谱性质研究

合成了一种席夫碱结构的罗丹明B衍生物.研究表明,该衍生物能与Fe3+形成稳定配合物,同时伴随显著的荧光增敏和吸收增强.衍生物不仅对Fe3+呈现良好的荧光及比色探针性能,其与金属离子形成的配合物也是一种研究牛血清白蛋白的高灵敏荧光探钊.     

莲子蛋白组分二级结构的研究

对莲子蛋白质进行了Osborne蛋白质分类。采用傅里叶变换红外光谱(FTIR)对清蛋白、球蛋白、醇溶蛋白和谷蛋白进行二级结构分析。应用去卷积和曲线拟合方法对四种蛋白组分的酰胺Ⅰ和Ⅲ带进行分析,清蛋白和球蛋白之间以及醇溶蛋白和谷蛋白之间各相应子峰峰位和二级结构峰面积百分比差异较小,但前两者各相应子峰峰位与后两者略有差异;而前两者各相应二级结构峰面积百分比与后两者有较大差异,特别是前两者的各相应有序结构(α-螺旋+β-折叠)峰面积的百分比明显大于后两者。用0.1 mol.L-1NaCl溶液提取的球蛋白和清蛋白有序结构含量均在55%左右,而醇或碱提的醇溶蛋白和谷蛋白的有序结构含量仅为40%左右,盐提的蛋白质二级结构有序性和稳定性更高。     

光谱法研究1,3-硫杂杯[4]罗丹明乙二胺酰胺衍生物对Fe3+的探针性能

利用硫杂杯[4]芳烃衍生物与罗丹明乙二胺发生酰化反应,合成了2个具有双罗丹明基团的1,3-硫杂杯[4]罗丹明乙二胺酰胺衍生物.在实验条件下,衍生物与Fe3+均能形成1:1配合物,配合物的形成诱导了衍生物分子中罗丹明基螺环开环,而表现出良好的荧光和比色探针性能.1,3-硫杂杯[4]罗丹明酰胺-2,4-酯对Fe3+的选择性...     

准滑模控制应用于行人通道的交通瓶颈

单向行人交通在瓶颈处极易发生堵塞,设置障碍会阻碍行人通行,却能保证瓶颈处通畅.本文将准滑模控制引入LWR模型中,理论推导控制变量.在三车道宏观交通流模型基础上,模拟瓶颈处的障碍对行人流的影响,解释设置障碍的作用.研究表明准滑模控制变量的设置与阈值有关,当阈值对应基本图的流量最大点时,行人流量能保持最大值,达到提高单向行人交通瓶颈处的行人流通过效率. 关键词： 交通瓶颈 准滑模控制 LWR模型     

考虑意外事件对交通流影响的元胞自动机交通流模型

在NaSh模型的基础上,考虑交通事故和养护路段等意外事件对高速公路交通流的影响,建立了有意外事件影响的在车道管制下的高速公路交通流元胞自动机模型,并进行数值模拟. 研究发现:意外事件对高速公路交通流有明显影响,并且意外事件对交通流的影响在某一密度值范围内尤其明显,且意外事件堵塞点在第一车道比在第二车道对交通流的影响小;同时,在该密度值范围内,意外事件堵塞时间和堵塞路段长度越长,对交通流的影响就越大. 关键词： 元胞自动机 交通流 意外事件     

钶铁矿型MnNb2O6的熔盐法合成、钒掺杂与磁性研究

采用了熔盐法新工艺制备了纯相与掺钒的MnNb₂O₆粉晶,利用X射线衍射仪(XRD),扫描电子显微镜(SEM),能谱分析(EDX),透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)和电子衍射(SAED)分析了其物相、形貌及微结构.结果表明合成产物为正交晶系钶铁矿型MnNb₂O₆;在不同的熔盐中合成出了棒状、片状与长方体形貌的纯相产物.讨论了温度与掺杂对结构与形貌的影响,HRTEM与SAED分析表明了产物的各向异性生 关键词： 熔盐法 结构与形貌 掺杂 反铁磁性     

界面条件下线型超声相控阵声场特性研究

开展了界面条件下线型超声相控阵声场特性的研究.将带有楔块的超声相控阵问题合理简化为液固界面的情况进行讨论.根据射线声学理论,计算了单阵元在液固界面存在时的辐射声场,进而推导了聚焦法则,得到了超声线型阵在液固界面存在时的声场、位移场表达式.对安装在楔块上的相控阵换能器的辐射声场进行了仿真,并讨论了聚焦对换能器轴向和横向声场的影响,结果表明利用聚焦能提高分辨率和灵敏度,但聚焦区域之外声束性能更差,在实际检测中要合理利用聚焦. 关键词： 超声相控阵 界面 声场 聚焦