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31.
CATALYTIC ACTION AND DESTRUCTION OF PROTOHEMATIN DURING PEROXIDE DEPENDENT LUMINOL CHEMILUMINESCENCE
Abstract— The catalytic action of protohematin was studied during the H2 O2 -dependent chemiluminescent luminol reaction. In spite of the fact that the catalyst was ultimately inactivated, the average protohematin molecule catalyzed the consumption of about 103 molecules of luminol. The inactivation of catalyst and the initial consumption of luminol were studied during the luminescent reaction with different concentrations of reactants. A scheme accounting for the experimental observations is proposed. The formation of a primary protohematin-H2 O2 complex is followed by binding of luminol, resulting in a ternary complex. A nucleophilic attack by a second molecule of H2 O2 on the luminol molecule results in light emission from excited aminophthalate via a hypothetical peroxide adduct. The destruction of protohematin occurs via the attack of H2 O2 on the porphyrin structure of the protohematin-H2 O2 complex. Second order rate constants for the destruction of protohematin, the formation of the luminol complex and the nucleophilic attack of H2 O2 are presented. 相似文献
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Constable EC Figgemeier E Housecroft CE Olsson J Zimmermann YC 《Dalton transactions (Cambridge, England : 2003)》2004,(13):1918-1927
The synthesis and electronic properties of dinuclear ([(bipy)2Ru(I)M(terpy)][PF6]4(bipy = 2,2'-bipyridine, terpy = 2,2':6',2'-terpyridine; M = Ru, Os)) and trinuclear ([[(bipy)2Ru(I)]2M][PF6]6 M = Ru, Os, Fe, Co) complexes bridged by 4'-(2,2'-bipyridin-4-yl)-2,2':6',2'-terpyridine (I) have been investigated and are compared with those of mononuclear model complexes. The electrochemical analysis using cyclic voltammetry and differential pulse voltammetry reveals that there are no interactions in the ground state between adjacent metal centres. However, there is strong electronic communication between the 2,2'-bipyridine and 2,2':6',2'-terpyridine components of the bridging ligand. This conclusion is supported by a step-by-step reduction of the dinuclear and trinuclear complexes and the assignment of each electrochemical process to localised ligand sites within the didentate and terdentate domains. The investigation of the electronic absorption and emission spectra reveals an energy transfer in the excited state from the terminating bipy-bound metal centres to the central terpy-bound metal centre. This indicates that the bridge is able to facilitate energy transfer in the excited state between the metal centres despite the lack of interactions in the ground state. 相似文献
37.
Rubber covered cylinders in rolling contact are studied in two cases; rolling over a flat surface and rolling over a groove. In the first case, two different finite element procedures are compared for the purpose of investigating if computational savings can be made when taking amplitude dependent effects into account by using a modified viscoelastic steady state rolling procedure. This procedure is compared with using a more expensive overlay method with an elastoplastic-viscoelastic material model. The two procedures and material models are shown two give equal results in the flat surface case. For the case of rolling over a groove, it is shown how the non-linear dynamic material characteristics of the rubber layer influence the rolling contact. The groove filling capacity of the rubber is shown to be strongly dependent on the material model. It is shown that amplitude dependent rubber materials have better ability to fill out contact surface irregularities such as a groove. 相似文献
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We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions. 相似文献
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Ibrahim Kayali Mohammad Karaein Khawla Qamhieh Salam Wadaah Wisam Ahmad Ulf Olsson 《Journal of Dispersion Science and Technology》2013,34(1):10-17
Bicontinuous and water-in-diesel microemulsions were formulated using single nonionic alkyl poly glycol ethers combined with hydrophilic alcohol ethoxylates. The phase behavior at temperatures ranging from 0°C to 50°C was investigated. Visual inspection as well as cross-polarizers were used to detect anisotropy. The fish phase diagrams were determined. The presence of the hydrophilic alcohol ethoxylates was necessary to initiate both types of microemulsions. Increasing the hydrophobic chain length of the surfactant led to a wider range of temperature stability at lower surfactant concentration. Meanwhile, increasing the ethylene oxide units in the headgroup by two units led to a phase diagram that is dominated by lyotropic liquid crystal. The formulated water in diesel microemulsions were tested experimentally in a 4-cylinder diesel engine. From this it is observed that the emissions of NOx, soot, and CO2 were reduced substantially compared to neat diesel, while for the CO the reduction occurs just at low load. 相似文献
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N. Nakamura Y. Yamaguchi B. Häkansson U. Olsson T. Tagawa H. Kunieda 《Journal of Dispersion Science and Technology》2013,34(1-2):535-557
Sucrose monoalkanoates (SE) form microemulsions by mixing with lipophilic cosurfactants such as the middle-chain alcohols, or sucrose polyalkanoates. In the case that sucrose monododecanoate is combined with hexanol, a middle-phase microemulsion is produced and coexists with excess water and oil phases at optimum mixing fraction of SE and hexanol. The bicontinuous structure of the microemulsion was confirmed by means of self-diffusion coefficient on NMR measurement. A larger solubilization capability of oil is attained to a mixed mono- and poly-dodecanoate system than that of the middle-chain alcohol. It is probably due to the location of most of surfactant molecules at the micro-interface inside the microemulsion. In this system, instead of forming a three-phase region, a lamellar liquid crystal intrudes into multi-phase region since the surfactant layer is rather rigid as which was supported by the results of SAXS and ESR measurements. Further addition of a short-chain alcohol such as propanol to the mixed system leads to the flexible interface, as a consequence three-phase microemulsion with large solubilization is formed. 相似文献