Cronobacter sakazakii还原作用对针铁矿晶体结构的影响

厌氧条件下,Cronobacter sakazakii以乙酸钠作为电子供体,针铁矿中Fe(Ⅲ)作为电子受体进行生命活动,其新陈代谢过程伴随Fe(Ⅲ)的还原。细菌增殖和稳定生长过程中不停还原针铁矿并大量累积Fe(Ⅱ);当细菌衰亡时,Fe(Ⅱ)的产生随之减缓;细菌的活动停止时,Fe(Ⅱ)不再积累并最终保持稳定。同步辐射XRD测试表明,微生物还原作用后针铁矿出现了一系列新衍射峰：4.8、6.03、6.13、6.84、7.7和11.4 峰,可能形成具层状结构的新物相。在XANES图谱中Fe主吸收峰向低能量方向移动1 eV,边前峰峰位中心向低能量方向移动且峰面积减小,表明Cronobacter sakazakii的异化Fe(Ⅲ)还原作用使针铁矿中Fe氧化态降低,矿物晶体结构发生了变化。     

XRD定量相分析方法及其在湖泊沉积研究中的应用

定量XRD方法经历了提出、发展与完善、融合与推广3个阶段,形成标样法和无标法两类方法。其中一些被应用到湖泊沉积上以挖掘矿物定量信息;而湖积物的复杂性又使得其存在误差大、耗时、费力等缺陷,也出现了各种改进方法,与其它手段整合似乎成为必然。但定量XRD方法在湖泊沉积与环境演化上的应用价值很大,极具发展空间。     

CuCl2—石墨层间化合物的结构及电化学性能研究

用直接反应法制备了C/CuCl2 从 6 .3- 88.2的五种不同的CuCl2 -石墨层间化合物 .X射线粉末衍射分析指出它们分别为一阶、一二混阶、二阶和高阶 (大于二阶 )石墨层间化合物 ,Ic(°A)分别为 9.4 6、9.4 6 /11.6 3、12 .0 99、15.74、18.394 °A。通过循环伏安法对一阶、一二混阶层间化合物的电化学性能进行了研究 ,并测试了作为锂电池阴极材料的电池充放电循环性能     

Asymmetric X-ray diffraction peak of metamorphosed carbonaceous material

Abstract It was revealed that the asymmetric X-ray diffraction peak of metamorphosed carbonaceous material was a combination of two types of symmetric peaks from the coaly material and graphite crystallite. Numerical synthesis using the two symmetric peaks shows the graphitization process observed in a metamorphic sequence is accompanied by a continuous change of the peak shape and apparent interplanar spacing. Based on the analytical results and geological observations, it is suggested that graphitization of carbonaceous material consists of two processes: (i) the formation of graphite crystallites at the expense of the coaly material through the formation of transitional material and the increasing abundance of crystallites which is observed in the chlorite zone; and (ii) growth of crystallites forming well-ordered graphite, which occurs in the higher-grade zone.     

Quantification of clay minerals by combined EWA/XRD method

Illite has been considered the main constraint on permeability in the Morecambe Gas Field, East Irish Sea, UK. Previous research has emphasized the morphology rather than the amount of clay minerals. By applying a new method of clay mineral quantification, EWA/XRD, and applying statistical analysis methods, we are able to establish a quantitative model of illite distribution in the field. The result also leads to a better understanding of permeability distribution in reservoir sandstones.     

H T -XRD study of synthetic ferrian magnesian spodumene: the effect of site dimension on the P 21/ c → C 2/ c phase transition

 Ferrian magnesian spodumene was synthesized in the MLFSH system at P=0.4 GPa, T=700 °C, fO₂=NNO+2.3. The space group at room T is P2₁/c [a=9.638(3) ?, b=8.709(2) ?, c=5.258(2) ?, β=109.83(3)^∘, V=415.2 ?³]. The structure is topologically equivalent to that of ferrian spodumene, LiFeSi₂O₆, and has two symmetrically independent tetrahedral chains, A and B, and two independent octahedral sites, M1 and M2. The crystal-chemical composition was determined combining EMP, SIMS and single-crystal XRD analysis, yielding ^M2(Li_0.85Mg_0.09Fe²⁺ _0.06) ^M1(Fe³⁺ _0.85Mg_0.15)Si₂O₆. Li is ordered at the M2 site and Fe³⁺ is ordered at the M1 site, whereas Mg (and Fe²⁺) distribute over both octahedral sites. Structure refinements done at different temperatures (25, 70, 95, 125, 150 and 200 °C) allowed characterization of a reversible displacive P2₁/c→C2/c transition at 106 °C. Previous HT-XRD studies of Li-clinopyroxenes had shown that the transition temperature is inversely related to the size of the M1 cation. For the crystal of this work, the aggregate ionic radius at M1 is longer than that of ferrian spodumene, for which the transition temperature is −44 °C. The higher transition temperature observed can only be explained on the basis of the shorter aggregate radius at the M2 site (due to the presence of Mg substituting after Li), in keeping with the results obtained for ferromagnesian P2₁/c pyroxenes. The effects of all the chemical substitutions must be considered when modelling transition temperatures and thermodynamic behaviour in clinopyroxenes. Received: 7 May 2002 / Accepted: 23 October 2002     

Mineral reactions during coke gasification with carbon dioxide

Coke degradation in the blast furnace is influenced by its inherent mineral matter. Coke gasification affects the composition of the inherent mineral matter and would therefore be expected to change its effect on coke degradation. Four cokes prepared in a laboratory oven were exposed to carbon dioxide (100%) at approximately 900 °C for different carbon conversion levels, namely 15% and 75%. The mineralogy of the raw and reacted cokes was qualitatively and quantitatively determined. Gas composition was found to have a more significant effect on mineralogy than temperature; the mineralogy (qualitative and quantitative) being dramatically affected by carbon dioxide, whereas treatment at 900 °C in the absence of carbon dioxide resulted in little change. During gasification the reduced phases underwent transformations due to oxidation by carbon dioxide. Oxidation of the reduced phases enabled their reaction with adjacent minerals. Also, as gasification proceeds, the carbon in contact with the mineral matter is consumed, diminishing the contact surface area between them.     

江苏镇江沸石矿石特征研究

通过对江苏镇江沸石矿石某钻孔样品和开采露头捡块样进行X衍射分析、化学成分分析、吸铵量分析、吸蓝量分析、阳离子交换容量、酸碱度分析等,与样品的颜色相结合分析沸石特征,该钻孔沸石岩矿石的矿物组成主要为斜发沸石、蒙脱石等。     

老挝北部黄色图章石的矿物成分及微量元素特征

老挝北部黄色图章石(又称老挝北部黄料)呈明亮的黄色至褐黄色,多见水波纹状内部纹理,与我国图章石中的田黄外观特征具有一定相似性。本文运用X射线粉晶衍射(XRD)、红外光谱(FTIR)、拉曼光谱(LRM)、扫描电子显微镜(SEM)、电子探针(EPMA)、激光剥蚀等离子质谱(LA-ICP-MS)、全铁化学分析等测试方法对其矿物组成、微量元素及产地特征等进行了研究。结果表明,老挝北部黄料的主要组成矿物单一,为无序地开石,杂质矿物包括重晶石、锐钛矿、硬水铝石和赤铁矿等,其中地开石颗粒表面平整,呈板状紧密排列;萝卜纹主要呈枝状、短脉状零星分布在基体中;老挝北部黄料的黄色由Fe~(3+)所致,且颜色深浅与Fe~(3+)含量呈正相关关系,其Cr、Rb、Sr含量低于田黄,Ga含量高于田黄。通过多元统计判别分析法可将老挝北部黄料和田黄进行有效区分,其判别函数对未知样品进行验证的正确率可达92. 9%,且模型的可靠性较高。通过稀土元素配分模式图可以直观区分老挝北部黄料和田黄。