中温下热解对半焦燃烧反应性的影响

用热天平（TGA）和粉末X射线衍射方法（XRD）分别测量了两种低变质程度烟煤和一种无烟煤的半焦在400-1400℃热解过程中燃烧反应性及其结构的变化,探讨了低变质煤的反应性变化的原因。研究发现,半焦反应性下降主要与热解过程中半焦晶格化与矿物质催化作用的逐渐消失有关,温度低于900℃,原煤脱去大部分挥发份形成的半焦进一步热解时,晶格化现象不很显著,但反应性明显下降,反应性的降低主要与煤中矿物质在热解过程中的失活有关。     

Atomic force microscopy in the photochemistry of chalcones

The application of atomic force microscopy (AFM) to photodimerization of crystalline chalcones provides new insights into the detailed mechanisms of solid-state reactions on the molecular level. Well-directed long-range transport phenomena are found which reach far beyond the crystal lattice distances. Reactions occur in the surface region where the light is absorbed. Characteristic features are built up that depend on crystal structure and crystal face. This could not be foreseen by previous theories based solely on a topochemical postulate/principle. There is now a much more intimate correlation of crystal structure with solid-state reactivity and this is directly studied and proven experimentally by AFM. Even solid-state reactions which are in opposition to topochemistry can be studied and understood on a molecular basis. The three-dimensional resolution of undisturbed insulating surfaces which is obtained by AFM is not available by any other technique.     

Sulphidation of an oxidic CoMo/Al2O3 catalyst under practical conditions: different kinds of sulphur species

The sulphidation of a CoMo/Al₂O₃ hydrotreating catalyst was studied under pressure and flow conditions close to industrial practice. The sulphiding mixture contained equal amounts of H₂S and CH₄ diluted in hydrogen under 3.9 MPa total pressure. The oxidic precursor was flushed by the reagent gas at 40°C for 10 h, then the temperature was raised to 400°C within 2 h. Mass variation was continuously recorded by means of a suspension magnetic balance, and the gas phase was analysed by mass spectrometry. Sulphur contents were also determined at intermediate temperatures by chemical analyses. Thus, mass variations due to the presence of adsorbed species or to the formation of CoMo sulphides could be distinguished. The rapid gain in mass noted at 40°C was mostly due to adsorption of H₂S over the oxidic solid, since it increased with H₂S partial pressure. At this stage, however, a small amount of the reactive oxygen was already exchanged for sulphur. Upon raising the temperature, the mass decreased due to a combination of desorption and sulphiding steps. Above 140°C, H₂S consumption was evidenced, together with water production, and the rate of sulphiding increased with the H₂S partial pressure. At 300°C, the mass variation was close to that expected for complete transformation into Co₉S₈ and MoS₂. Above 350°C, the mass further increased due to the replacement of adsorbed water by H₂S. At 400°C, an important excess mass was observed at all H₂S partial pressures. Thus, the adsorption sites on the metal sulphides are essentially saturated by H₂S species under practical conditions.     

南京二叠系栖霞阶灰岩中燧石碱活性的探讨

对南京二叠系栖霞阶灰岩中的矿物学研究表明,该燧石的碱活性不仅取决于α石英的晶体结构,而且还与燧石的矿物集合体构造有关。这种燧石非活性特征是由于其含有沥青质之故,沥青质的存在抑制了碱-集料反应的进行。     

大环单氮杂冠醚与丙烯腈的自由基共聚反应竞聚率的测定及其共聚物的热力学性质研究

利用Fineman-Ross方法,在甲苯溶剂中测定了大环N-(4-乙烯基苄基)-1-单氮杂-m-亚苯基-34-冠-11单体与丙烯腈的共聚合反应的单体竞聚率,其值分别为3.99和0.19,并采用TGA和DSC简略地研究了共聚物的热力学性质.     

The relationship between cardiac reactivity in the laboratory and in real life.

Objective: An excessive cardiovascular response to acute stress is a probable risk factor for cardiovascular (CV) disease. Such reactivity is usually assessed from the CV response to laboratory stressors. However, if it is a risk factor, correlated responses must occur in real life. Design: In the present study, we investigated the relationship between the heart rate (HR) response to five laboratory stressors and HR reactivity in the field. Measures: HR variation, the response to a real life stressor (public speaking), and the increase in HR with periods of self-reported tense arousal. Ambulatory HR, activity and posture were measured continuously over a 7-hr period. Results: The HR increase to laboratory stressors did not relate to HR variation consistently, but it did relate to the other two field measures. Conclusion: The results suggested that a tendency to increased HR reactivity may be a risk factor for cardiovascular disease when combined with exposure to stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

液氨预处理对纤维素可及度和反应性的影响

棉短绒纤维素在25℃和1．03MPa压力下分别用液氮预处理120min和180min,纤维素的可及度和反应性大为提高,与未经处理的棉短绒比较．120min和180min液氨处理样的水吸附保持值（VWR）分别提高41％和60％,碘吸附值（VIS）分别提高90％和131％。液氮处理纤维素的羧甲基化反应速率也有较大提高.CMC水溶液的透明度和H-NMR谱的分析表明,取代基沿分子链分布的均一性和失水葡萄糖单元上三个羟基分布的均一性都有明显的提高。     

Hydrocarbon conversion on ZSM-5 in the presence of N2O: relative reactivity

Conversions of methane, ethane, propane, benzene and hydrogen were studied on HZSM-5 at 418°C using binary mixtures R1:R2:N₂O:He (where R1, R2 are substances under study). Relative reactivities were determined, and it was shown that the rates of conversion of hydrocarbons are determined by the strengths of C–H bonds (H–H for hydrogen). This revised version was published online in July 2006 with corrections to the Cover Date.     

P[CF3(CF2)5CH2MA‐co‐MMA] and P[CF3(CF2)5CH2MA‐co‐BA] copolymers: Reactivity ratios and surface properties

This study aimed at reducing the surface energy of coatings by copolymerization of commonly used monomers with fluorine‐containing monomers. Copolymers of 1,1‐dihydroperfluoroheptyl methacrylate (FHMA) and methyl methacrylate (MMA) or butyl acrylate (BA) are prepared by low‐conversion polymerization in solution. Using ¹H‐NMR data and nonlinear least‐squares data fitting, reactivity ratios of these systems at 80°C are determined to be r_FHMA = 1.31, r_MMA = 0.76, and r_FHMA = 3.15, r_BA = 0.38, respectively. We assume that the penultimate unit effect plays an important role in these systems. Introduction of the perfluoroalkyl side chain lowers the polymer surface energy significantly; copolymers of MMA and FHMA show a reduction in total surface energy of about 50 % at a content of 15 mol % FHMA as compared with pure PMMA. The attainable reduction in surface energy is much larger than with, for example, Teflon. This is due to the preferential adsorption of the —CF₃ groups of the fluoroalkyl side chain, if compared to that of the —CF₂— groups of Teflon. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 159–165, 2001