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排序方式: 共有51条查询结果,搜索用时 93 毫秒
41.
R. M. Godbole Sourendu Gupta J. Lindfors 《Zeitschrift fur Physik C Particles and Fields》1990,47(1):69-73
We investigate the double parton scattering production ofW ±+jets in proton colliders. At high energies an observable signal is expected from double parton collisions when events with small transverse momentumW together with two jets balancing inp T are selected. Double parton scattering is also a potentially serious background to several rare processes whose signal is aW ++W ?(→ev+jets) final state. A simplep T W cut seems to be sufficient to separate the genuineW-pair events from the double scattering background. 相似文献
42.
N. Kumar R. Byggningsbacka L. -E. Lindfors 《Reaction Kinetics and Catalysis Letters》1997,61(2):297-305
The reaction ofn-butane aromatization was carried out over Ni-ZSM-5 and Cu-ZSM-5 zeolite catalysts prepared by using Ni and Cu impregnated
silica fiber during the process of ZSM-5 zeolite synthesis. The catalysts prepared were characterized by X-ray powder diffraction,
nitrogen adsorption and X-ray fluorescency. The acidic properties of the catalysts were investigated by temperature-programmed
desorption of ammonia using a mass spectrometer equipped with a QTMD detector. The effect of catalyst pretreatment, reaction
temperature, and time on stream on the reaction ofn-butane to aromatic hydrocarbons were investigated. The modification of ZSM-5 by Ni and Cu increased the selectivity to aromatic
hydrocarbons. The state of Ni and Cu and their stabilization in the ZSM-5 structure was highly influenced by the mode of catalyst
pretreatments. 相似文献
43.
Fredrik Sundfors Lajos Höfler Róbert E. Gyurcsányi Tom Lindfors 《Electroanalysis》2011,23(8):1769-1772
Accumulation of water in ion‐selective membranes, can lead to inconsistent potentiometric responses with solid‐contact ion‐selective electrode (SC‐ISE) formats, and hence it is essential to restrain their water uptake. We have used FTIR‐ATR spectroscopy to study how the water uptake is influenced by the intermixing of a poly(3‐octylthiophene) (POT) SC and a poly(methyl methacrylate):poly(n‐decyl methacrylate) (PMMA:PDMA) based polymeric membrane matrix, the only SC‐ISE system for which direct evidence was provided on the aqueous layer elimination. Numerical simulations of the FTIR‐ATR spectra of 1 or 5 wt% POT containing PMMA:PDMA membranes showed that the addition of 5 wt% POT to the membrane lowered the equilibrium water uptake, whereas the diffusion coefficients of water in the membrane were found to be less affected. Consequently, POT is beneficial for preventing the formation of detrimental water layers in the SC‐ISE structure. 相似文献
44.
The two most promising approaches for preparing solid contacts (SCs) for polymeric membrane based ion‐selective electrodes (ISEs) are based on the use of large surface areas conducting materials with high capacitance (e. g., various carbon nanotubes) and redox active materials (e. g. conducting polymers). While many of the essential requirements for the potential stability of SCISEs were addressed, the E0 reproducibility and its predictability, that would enable single use of such electrodes without calibration is still a challenge, i. e., the fabrication of electrodes with sufficiently close E0 and slope values to enable the characterization of large fabrication batches through the calibration of only a small number of electrodes. The most generic solution seems to be the adjustment of the E0 potential by polarization prior to the application of the ion‐selective membrane. This approach proved to be successful in case of conducting polymer‐based solid contacts, but has to be still explored for capacitive solid contact based ISEs, which is the purpose of this paper. We have chosen a well‐established highly lipophilic multi‐walled carbon nanotube (MWCNT), i. e. octadecane modified MWCNT (OD‐MWCNT), that is investigated in the comparative context of a similarly lipophilic conducting polymer solid contact (a perfluorinated alkanoate side chain functionalized poly(3,4‐ethylenedioxythiophene)). While, the OD‐MWCNT based SCISEs had inherently small standard deviation of their E0 values (less than 5 mV) this could be further improved by external polarization and short circuiting the SCISEs. 相似文献
45.
Until now both ion‐to‐electron transducers as well as large surface area nanostructured conducting materials were successfully used as solid contacts for polymer‐based ion‐selective electrodes. We were interested to explore the combination of these two approaches by fabricating ordered electrically conducting polymer (ECP) nanostructures using 3D nanosphere lithography and electrosynthesis to provide a high surface area and capacitive interface for solid contact ion‐selective electrodes (SC‐ISEs). For these studies we used poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT(PSS)) films with 750 nm diameter interconnected pores as the intermediate layer between a glassy carbon electrode and a Ag+ ‐selective polymeric membrane. We also investigated the feasibility of loading the voids created in the polymer film with a lipophilic redox mediator (1,1’‐dimethylferrocene) to provide the respective ISEs with well‐defined/controllable E0 values. These expectations were fulfilled as the standard deviation of E0 values were reduced with almost an order of magnitude for 3D nanostructured SC‐ISEs filled with the redox mediator as compared to their redox mediator‐free analogs. The detrimental effect of the redox mediator extraction into the plasticized PVC‐based ion‐selective membrane (ISM) was efficiently suppressed by replacing the PVC‐based ISMs with a low diffusivity silicone rubber matrix. 相似文献
46.
Fredrik Weiland Muhammad Saad Qureshi Jonas Wennebro Christian Lindfors Taina Ohra-aho Hoda Shafaghat Ann-Christine Johansson 《Molecules (Basel, Switzerland)》2021,26(23)
Petrochemical products could be produced from circular feedstock, such as waste plastics. Most plants that utilize syngas in their production are today equipped with entrained flow gasifiers, as this type of gasifier generates the highest syngas quality. However, feeding of circular feedstocks to an entrained flow gasifier can be problematic. Therefore, in this work, a two-step process was studied, in which polypropylene was pre-treated by pyrolysis to produce a liquid intermediate that was easily fed to the gasifier. The products from both pyrolysis and gasification were thoroughly characterized. Moreover, the product yields from the individual steps, as well as from the entire process chain, are reported. It was estimated that the yields of CO and H2 from the two-step process were at least 0.95 and 0.06 kg per kg of polypropylene, respectively, assuming that the pyrolysis liquid and wax can be combined as feedstock to an entrained flow gasifier. On an energy basis, the energy content of CO and H2 in the produced syngas corresponded to approximately 40% of the energy content of the polypropylene raw material. This is, however, expected to be significantly improved on a larger scale where losses are proportionally smaller. 相似文献
47.
48.
J. Lindfors 《Zeitschrift fur Physik C Particles and Fields》1987,35(3):355-360
We presentW/Z-parton luminosities 1/s d L/dτ in the TeV energy region for suche + e ?,ep andpp collision processes where the intermediate vector bosonsW ± orZ 0 are in the initial state. 相似文献
49.
The normalized intensity fluctuations of arbitrary electromagnetic wave fields obeying Gaussian statistics are expressed in terms of the three-dimensional degree of polarization. This general formulation implies an important physical result concerning the polarization of planar fields and the dimensionality of the formalism. The results are expected to be particularly useful in intensity interferometry. 相似文献
50.
Fredrik Klingstedt Ahmad Kalantar Neyestanaki Lars-Eric Lindfors Tapio Ollonqvist Juhani Väyrynen 《Reaction Kinetics and Catalysis Letters》2000,70(1):3-9
Catalytic oxidation of model pollutants, simulating the emissions from small-scale biofuel combustion systems, was studied over different fresh, aged and sulfur poisoned Pd-MeO/-alumina (Me = Ni, Ce and La) catalysts. Release of chlorine and restructuring of PdO particles was believed to cause activation of the Pd-MeO supported catalysts. 相似文献