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31.
Hemocompatibility is an essential aspect of blood contacting polymers. Knowledge of the relationship between polymer structure and hemocompatibility is important in designing such polymers. In this work, the effect of swelling behavior and states of water on the hemocompatibility of poly(acrylonitrile-co-N-vinyl-2-pyrrolidone) (PANCNVP) films was studied. Platelet adhesion and plasma recalcification time tests were used to evaluate the hemocompatibility of the films. Considering the importance of surface properties on the hemocompatibility of polymers, static water contact angles were measured by both sessile drop and captive bubble methods. It was found that, on the film surface of PANCNVP with a higher NVP content, adhered platelets were remarkably suppressed and the recalcification time was longer. The total water content adsorbed on the PANCNVP film was determined through swelling experiments performed at temperatures of interest. Differential scanning calorimetry and thermogravimetric analysis were used to probe the states of water in the films. Based on the results from these experiments, it was hypothesized that the better hemocompatibility of PANCNVP films with higher NVP contents was due to their higher free water content, because water molecule exchange at the polymer/liquid interface, facilitated by a high free water content, is unfavorable for the formation of surface bound water, which causes poor hemocompatibility. [diagram in text]. 相似文献
32.
In 1949 Dirac published a paper in which he proposed various ways to combine special relativity with the Hamiltonian formulation of dynamics; these were referred toas forms and three differentforms, theinstant, thepoint, and thefront forms, were discussed. Dirac considered thefront form to be mathematically the most interesting. Despite this, thefront form appears to have been the least explored. This paper presents the results of a study of quantum mechanics in thefront form. 相似文献
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S. D. Pollington M. S. Ioffe M. Westergaard J. K. S. Wan 《Research on Chemical Intermediates》1995,21(1):59-68
A high-power microsecond pulsed microwave system operating in the X-band region was used for the catalytic conversion of methane. Microwave microsecond pulses at repetition rates of 50 and 80 Hz were used to initiate chemical reactions. The Microwave-Induced Acoustic technique was employed in combination with gas chromatography for on-line detection of chemical products. Methane was converted to C2 and C3 hydrocarbons. The selectivity of ethane in hydrocarbon products can be >90 %. The contribution of hydrogen evolution and carbon deposition has been shown to be important. A comparison between previous experiments performed with millisecond pulse durations is given. 相似文献
35.
Cecilia Wan Ying Chung 《Tetrahedron》2005,61(3):709-715
An insoluble polystyrene-supported triflating reagent has been prepared by suspension co-polymerization of N-(4-vinylphenyl)trifluoromethanesulphonimide, styrene and the JandaJel® cross-linker. This reagent, in the presence of triethylamine, allows for the efficient synthesis of aryl triflates from a wide range of phenols in a process that permits the desired product to be isolated from the reaction mixture in essentially pure form via several filtration and concentration operations. Adding to the utility of this reagent is its ability to be easily recovered, regenerated and reused. Both soluble and insoluble bifunctional polymers containing trialkylamine moieties in addition to triflimide groups were also prepared and examined as triflating reagents. Unfortunately these reagents afforded only modest yields of the desired products in representative reactions. 相似文献
36.
The time-resolved ESR signal of a triplet radical pair was detected upon excitation of a solid mixture of acridine and acridan at room temperature. The ZFS parameters of the triplet radical pair were determined to be D=−0.0100 cm−1 and E=0.00053 cm−1. The structure of the radical pair is discussed on the basis of the data. 相似文献
37.
The sorption and desorption characteristics of gold and silver on a polyhydroxamic acid chelating resin are described. Gold is quantitatively sorbed from 0.5 M nitric acid or neutral solutions, and readily eluted with 0.5% () potassium cyanide solution. Silver is removed from 0.05 M nitric acid or neutral solutions, and can be eluted with the cyanide solution or with 0.5 M nitric acid. Gold can be quantitatively separated from copper, iron and silver; gold and silver are sorbed from dilute cyanide solutions. Tests with river water and other eluting systems are reported. 相似文献
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This paper proves that circular vortex patches in the plane are stable for the nonlinear dynamical system generated by the Euler equations of incompressible fluids. This is achieved by establishing a relative variational principle in terms of either energy or angular momentum. Thus, we exploit and extend Arnold's idea in (1965, 1969) to a nonsmooth setting as well.Research partially supported by DOE contract DE-AT03-82ER12097 to the University of California, Berkeley 相似文献