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51.
Equilibrium exchange isotherms were determined for the exchange of Cu2+ with NaZSM-5 at varying Cu(Ac)2 concentrations in solutions of constant volume and zeolite weight. At low Cu2+ levels the solid scavenged all the copper ions. When copper could be detected in the equilibrated solutions, overexchange was observed. The extent of overexchange was higher at pH 6 than at pH 4. These results were analyzed in relation to catalytic activity.On leave from the Central Institute for Chemistry, Hungarian Academy of Sciences, H1525 Budapest, Hungary. 相似文献
52.
A new application of low-angle laser light scattering has led to a new instrument capable of characterizing the rubber particle size distribution of high-impact polystyrene (HIPS) containing particles as small as 0.1 μ. Rubber particle size distributions of several HIPS resins have been characterized, and the particle size ranking of resins using light scattering parallels the ranking of resins using photomicroscopy. Several solvents have been employed to suspend the HIPS rubber particles for the scattering determination. Swelling of the rubber phase has been found to be relatively insensitive to variations in rubber phase crosslinking when methyl ethyl ketone is used to suspend the rubber particles. Particle swelling in methyl ethyl ketone does not detract from the usefulness of the light scattering method for HIPS rubber particle size characterization. 相似文献
53.
Bleached and unbleached forms of a rosemary oleoresin (RO) in stripped and nonstripped soybean oil behave both as antioxidant
and prooxidant in a light-induced oxidative system. At 0.02 and 0.05% levels, RO had the greatest antioxidant activity, while
at 0.01 and 0.5% levels it had the highest prooxidant activity in both stripped and nonstripped soybean oil. Treatment of
both soybean oil systems with tertiary butylhydroquinone controlled light-induced oxidation of the oil better than did the
oleoresin treatments. The prooxidant activity of the 0.5% RO level was probably due to an excess of prooxidant components
being carried into the oil at that level, whereas the reduced antioxidant activity at 0.01% was probably due to the low initial
level of active antioxidant components being added to the oil.
Published as Journal Series No. 10072, Nebraska Agricultural Research Division, Department of Food Science and Technology,
University of Nebraska, Lincoln, NE 68583-0919. 相似文献
54.
Jan Quadflieg Mike Preuss Günter Rudolph 《Genetic Programming and Evolvable Machines》2014,15(4):433-476
We present the evolution and current state of the Mr. Racer car racing controller that excelled at the corresponding TORCS competitions of the last years. Although several heuristics and black-box optimization methods are employed, the basic idea of the controller architecture has been to take over many of the mechanisms human racing drivers apply. They learn the track geometry, plan ahead, and wherever necessary, adapt their plans to the current circumstances quickly. Mr. Racer consists of several modules that have partly been adapted and optimized separately, where the final tuning is usually done with respect to a certain racing track during the warmup phase of the TORCS competitions. We also undertake an experimental evaluation that investigates how the controller profits from adding some of the modules to a basic configuration and which modules are most important for reaching the best possible performance. 相似文献
55.
Calculation of mixture properties using the virial equation of state (VEOS) becomes tedious when the expression contains more than the second virial term. This paper describes a derivation procedure which permits relatively simple extension to any number of virial terms. We have used the fugacity derivation as an example of using the new technique and provide an equation for the fugacity coefficient using any number of terms and any number of components. 相似文献
56.
J. Richard Hall Carolyn A. L. Westerdahl Andrew T. Devine Michael J. Bodnar 《应用聚合物科学杂志》1969,13(10):2085-2096
Polyethylene, polypropylene, poly(vinyl fluoride) (Tedlar), polystyrene, nylon 6, poly(ethylene terephthalate) (Mylar), polycarbonate, cellulose acetate butyrate, and a poly(oxymethylene) copolymer were treated with activated helium and with activated oxygen. Mechanical strengths of adhesive-bonded specimens prepared from treated and from untreated coupons were compared. Polyethylene (PE) and polypropylene (PP) showed the greatest increases in bond strength. Oxygen and helium were both effective with polyethylene, but polypropylene showed no improvement when treated with activated helium. The results with excited helium parallel the effects of ionizing radiation on these two polymers, as does the appearance of unsaturation bands in the infrared (965 cm?1 in PE, and 887 and 910 cm?1 in PP). Active nitrogen produced excellent bond strength with polyethylene but not with polypropylene. Of the remaining polymers examined, Tedlar, polystyrene, and nylon 6 showed the greatest improvement in bondability after treatment, and Mylar showed moderate improvement. Polycarbonate, cellulose acetate butyrate, and the poly(oxymethylene) copolymer gave approximately two-fold increases in lap-shear bond strength. In several cases, significant differences in response to time of treatment and type of excited gas were found. 相似文献
57.
Sambasiva Rao Chinnamsetty Mike Espig Wolfgang Hackbusch 《Computing and Visualization in Science》2015,17(6):267-275
The computation of a six-dimensional density matrix is the crucial step for the evaluation of kinetic energy in electronic structure calculations. For molecules with heavy nuclei, one has to consider a very refined mesh in order to deal with the nuclear cusps. This leads to high computational time and needs huge memory for the computation of the density matrix. To reduce the computational complexity and avoid discretization errors in the approximation, we use mesh-free canonical tensor products in electronic structure calculations. In this paper, we approximate the six-dimensional density matrix in an efficient way and then compute the kinetic energy. Accuracy is examined by comparing our computed kinetic energy with the exact computation of the kinetic energy. 相似文献
58.
Mike Phillips 《Digital Creativity》2013,24(2):75-87
This paper explores the limitations of contemporary interface design and offers the potential of more profound forms of interaction by drawing on the rich and much older heritage of interactive art. Whilst HCI design is preoccupied with making the computer more simple to use, installation work, kinetic sculpture, and interactive multimedia art forms have generally been more concerned with the predicament of human/technological negotiation, whilst remaining a salient form of human communication. HCI activity sets out to make the complex systems of computing easy to understand and use, whilst interactive art often uses simple technology to make complex, inspiring and esoteric statements and experiences. In many ways the more simple and 'low resolution' the technology the more immersive, acute and intimate the experience. 'Low resolution' examples such as telephone-sex-lines are explored alongside more immersive systems, such as biofeedback interfaces, and other interactive experiments drawn from the 'technic' strand of art history. 相似文献
59.
Conventionally drought severity is assessed based on drought indices. Recently the Reconnaissance Drought Index (RDI) was
proposed to assess drought severity based on the precipitation to potential evapotranspiration ratio (P/PET). In this paper
RDI is studied as a bivariate index under a set of assumptions and simplifications. The paper presents a simple computational
procedure for estimating the P/PET ratio for selected reference periods varying from 3 to 12 months, for any return period
of drought. Alternatively, based on this procedure, the severity of any drought episode is rationally assessed. A bivariate
probability analysis is employed based on the assumption that P and PET values are normally distributed and often negatively
correlated. Examples for the application of the proposed procedure are presented using data from several meteorological stations
in Greece. It is shown that the assumption of normality of both P and PET holds for long periods at all examined stations. 相似文献
60.
Jo Towers Jennifer Hall Tina Rapke Lyndon C. Martin Heather Andrews 《Canadian Journal of Science, Mathematics, & Technology Education》2013,13(3):152-164
ABSTRACTIn this article, we review published literature that draws on autobiographical accounts of students' experiences learning mathematics. We summarize the main findings of the target literature and present recommendations for further research that will extend this field. Our review indicates that autobiographical and narrative methodological approaches have the potential to occasion important advances in our knowledge of students' experiences learning mathematics. However, relative to accounts of preservice teacher learning, there is a paucity of published research that documents the mathematics learning experiences of kindergarten to Grade 12 students. 相似文献