Grafting to Vinylpyrrolidone Polymers and Copolymers by the Ceric lon Method

Polymers and copolymers of vinylpyrrolidone were investigated as grafting substrates for methyl methacrylate using the ceric ion method. Ceric ion readily initiates methyl methacrylate grafting to commercial poly (vinylpyrrolidone) (PVP) of 360,000 nominal molecular weight. The resulting graft copolymer was surprisingly found to be an ABA triblock system with PVP in the center block. This conclusion is supported by three key pieces of evidence: first, selective degradation of the PVP/MMA graft copolymer showed two PMMA grafts per PVP chain: second, blocking of what are apparently hydroxylic or glycolic PVP end groups by reaction with phenyl isocyanate rendered the PVP unreactive to ceric ion grafting; third, if the PVP is prepared by methods which preclude formation of hydroxylic end groups, the PVP is unreactive to ceric ion grafting.

Vinylpyrrolidone polymers can be made graftable via ceric ion if N-methacryloyl-D-glucosamine (NMAG) is incorporated as a comonomer in the PVP backbone. Regardless of the method of preparation, incorporation of NMAG provides grafting sites which are highly reactive to ceric ion. At copolymer compositions up to 10 mole % NMAG, the methyl methacrylate graft copolymers are soluble in organic solvents. Above 10 mole % NMAG, the grafting reaction leads to cross-linking and formation of intractable gels.     

Extending the applicability of TG measurements to industry and to quality ensuring by dimensionless analysis

TheI _i=E _i/RT _i dimensionless evaluation is very suitable for describing the TG measurements according to theE _i/RT _i=lnA +n[ln(1–)_i]–ln(d/dr)_i equation. TheI _i andE _i functions make the comparison of the different TG measurements possible quantitatively in the case of more DTG peaks as well.TheI _i andE _i values as function of (1-)_i and 1/T _i open new way for further theoretical and practical studies by TG measurements. Such types of results are the quantitative determination of the effect of the measuring conditions, the measuring of the mechanochemical effect of grinding and among others the explanation of the self-hardening process of fly ashes of power stations.Strict connections exist between theI _i functions and the constants of the compensation effect (CE). These constants (tan, axis intersect) can be calculated directly from the average of the measured data of theI _i function making the introduction and theoretical and practical application of the idea of general activation energy (¯E) possible. The quantitative characterisation of the examined materials of the fine structure ofCE and of the thermal processes together proves the extending importance of TG measurements from industrial and material qualification aspects as well.The author thanks gratefully to Professor Márta Fehér mathematicien, Head of the Department of Philosophy at the Technical University of Budapest for the consultations and for the encouragements.     

Reply to the comment by Vignale et al

In our Reply, we first explain why the proof of Vignale and Rasolt that the basic variables are the density and paramagnetic current density is in error. We then refute the comments by Vignale et al with regard to our work. © 2012 Wiley Periodicals, Inc.     

First principles potential for the acetylene dimer and refinement by fitting to experiments

We report the definition and refinement of a new first principles potential for the acetylene dimer. The ab initio calculations were performed with the DFT-SAPT combination of symmetry-adapted intermolecular perturbation method and density functional theory, and fitted to a model site-site functional form. Comparison of the calculated microwave spectrum with experimental data revealed that the barriers to isomerization were too low. This potential was refined by fitting the model parameters in order to reproduce the observed transitions, an excellent agreement within ~1 MHz being achieved.     

煤经气化制液体燃料及其高温煤气净化研究进展

煤炭是中国最重要的能源.煤炭的有效利用不仅要提高效率,而且要降低污染物和温室气体二氧化碳的排放.相对于传统的煤燃烧利用技术,煤经气化生产各种化学产品被认为是先进的煤洁净利用的重要途径.几乎所有的目前由日趋枯竭的石油资源生产的化学产品,都可经煤气化从合成气转化获得.本文介绍了中国科学院山西煤炭化学研究所近年来在煤经气化制液体燃料及其高温煤气净化方面的研究进展,主要包括煤的灰熔聚流化床气化、高温气体净化、浆态床反应器铁基催化剂费托合成、低碳醇合成以及一步法二甲醚合成等技术.     

A traceability protocol to the SI by gravimetric analysis

 An example is presented of a traceability protocol for the measurement of a single-element strontium reference material solution, executed by a "primary" method of measurement for certification. The method of measurement is briefly described together with the measurement equation and the associated calculations for the estimation of uncertainties. This is followed by a discussion and estimate of each component of uncertainty associated with the measurement, together with a final estimate of uncertainty. The final estimate of uncertainty compares well with observed uncertainties for two previous laboratory measurements of the reference material. Received: 21 February 1998 · Accepted: 17 August 1998