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941.
Steffen Knust Andreas Kuhlmann Alejandro G. Orive Teresa de los Arcos Guido Grundmeier 《Surface and interface analysis : SIA》2020,52(12):1077-1082
The adsorption of octadecyl phosphonic acid (ODPA) on oxide-covered surfaces of ZnMgAl alloy coatings is described as a function of a dielectric barrier discharge (DBD) pretreatment step. The ODPA monolayer formation enables the investigation of the influence of the DBD treatment on the resulting interfacial bond formation and surface coverage. Surface characterisation by means of surface spectroscopy (PM-IRRAS, XPS) and surface electrochemistry (cyclic voltammetry) showed that the DBD pretreatment with Ar, Ar/O2 and Ar/H2O gas mixtures leads to improved barrier properties of the adsorbed ODPA monolayer. Moreover, during ODPA monolayer formation from ethanolic solution, a partial etching of the surface oxide layer occurs. 相似文献
942.
Fabio Marchetti Guido Pampaloni Calogero Pinzino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13962-13969
The 1:3 reactions of the alkoxy arenes 1,4‐(MeO)2C6H4 and 1,4‐F2‐2,5‐(MeO)2C6H2 with TaF5 in chloroform at 40–50 °C resulted in formation in about 35 % yield of the long‐lived radical cation salts [1,4‐(MeO)2C6H4][Ta2F11] ( 2 a ) and [1,4‐F2‐2,5‐(MeO)2C6H2][Ta2F11] ( 2 b ), respectively. The non‐alkoxy‐substituted [arene][M2X11] [M=Ta, X=F: arene=C6H5Me ( 2 c ), 1,4‐C6H4Me2 ( 2 d ), C6H5F ( 2 e ), C6H5NO2 ( 2 f ); M=Nb, X=F: arene=C6H5Me ( 4 a ), 1,4‐C6H4Me2 ( 4 b ), C6H5F ( 4 c ), C6H5NO2 ( 4 d ); M=Ta, X=Cl: arene=1,4‐C6H4Me2 ( 5 )] were obtained from the 3:1 reactions of MX5 with the appropriate arene in chloroform at temperatures in the range 40–90 °C. Compounds 2 – 5 were detected by EPR spectroscopy (in CHCl3) at room temperature, and their gas‐phase structures were optimized by DFT calculations. Formation of the MIV species [MX4(NCMe)2] [M=Ta, X=F ( 3 a ); M=Nb, X=F ( 3 b ); M=Ta, X=Cl ( 3 c )] was ascertained by EPR spectroscopy on solutions obtained by treatment of the reaction mixtures with acetonitrile. Non‐selective reactions occurred upon combination of 1,4‐F2‐2,5‐(MeO)2C6H2 with AgNbF6 (in CH2Cl2) and 1,4‐(MeO)2C6H4 with SbF5. 相似文献
943.
Bart De Spiegeleer Bram Baert Elien Vangheluwe Ilse Becue Jan De Smet Pieter Spanoghe Christophe Wille Paul Van der Meeren Guido Slegers 《Journal of solution chemistry》2007,36(7):835-843
Simulated intestinal fluids (SIFs) are described in the United States Pharmacopoeia (USP) and the International Pharmacopoeia
(IntPh) as recommended dissolution media for the characterization of solid drugs. This study was carried out to compare their
wettability properties. Six different model substrates were used as surrogates for solid drugs. These surrogate solid substrates
were characterized by the Lifshitz-van der Waals, electron donor and electron acceptor terms, which are the three components
of the total surface energy obtained by the van Oss model, which is based upon Young’s equation. Contact angles of the SIFs
on the surrogate solid-substrates were determined dynamically by image analysis up to five minutes after applying a drop of
the fluid on the solid surface. Observed time-dependent spreading behavior was accounted for by a linear extrapolation of
the experimental data to zero contact time to obtain the apparent equilibrium contact angle at zero time. Additionally, the
pH, osmolality and buffer capacity of the SIFs were experimentally determined. Although some differences in osmolality and
buffer capacity were observed, no statistically significant differences in the wetting properties of the three SIFs were detected.
This confirms recent findings that there are no observed differences in dissolution behavior among these simulated intestinal
fluids. Harmonization of these SIFs is thus recommended. 相似文献
944.
Carlos Guido Bollini Mario Giambiagi Myriam Segre de Giambiagi Aloysio Paiva de Figueiredo 《Structural chemistry》2001,12(2):113-120
Through the graphical method proposed, it is possible to create a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved, if there are more than three. For 5-c rings, three basic structures are required; the eventually different values are 12. Unlike the 6-c case, it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings, including heteroatoms, the original degeneracy of benzene splits, leading eventually to 60 different Iring values. 相似文献
945.
946.
Guido Gherardi 《Mathematical Logic Quarterly》2006,52(6):625-642
The focus of this paper is the incomputability of some topological functions (with respect to certain representations) using the tools of Borel computability theory, as introduced by V. Brattka in [3] and [4]. First, we analyze some basic topological functions on closed subsets of ?n , like closure, border, intersection, and derivative, and we prove for such functions results of Σ02‐completeness and Σ03‐completeness in the effective Borel hierarchy. Then, following [13], we re‐consider two well‐known topological results: the lemmas of Urysohn and Urysohn‐Tietze for generic metric spaces (for the latter we refer to the proof given by Dieudonné). Both lemmas define Σ02‐computable functions which in some cases are even Σ02‐complete. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
947.
Teodor Gabriel Crainic Guido Perboli Miriam Pezzuto Roberto Tadei 《European Journal of Operational Research》2007
This paper addresses the issue of computing the asymptotic worst-case of lower bounds for the Bin Packing Problem. We introduce a general result that allows to bound the asymptotic worst-case performance of any lower bound for the problem and to derive for the first time the asymptotic worst-case of the well-known bound L3 by Martello and Toth. We also show that the general result allows to easily derive the asymptotic worst-case of several lower bounds proposed in the literature. 相似文献
948.
Maurizio Canetti Fabio Bertini Aurelio De Chirico Guido Audisio 《Polymer Degradation and Stability》2006,91(3):494-498
The influence of lignin on the thermal degradation of isotactic polypropylene, investigated by thermogravimetric analysis, is reported in this article. Polypropylene blends containing 5 and 15 wt% of lignin were prepared by mixing the components in a screw mixer. An increase in the thermal degradation temperature of the blends was observed as a function of lignin content, in both oxidative and non-oxidative conditions. The increase is noticeably marked for the experiments carried out in air atmosphere, where the interactions between the polypropylene and the lignin lead to the formation of a protective surface able to reduce the oxygen diffusion towards the polymer bulk. Morphological analyses were carried out with optical and electronic microscopy, to evaluate the degree of dispersion of the lignin in the polypropylene matrix. X-ray techniques were employed to study the influence of lignin on the structure of the blended polypropylene. 相似文献
949.
Stijn Viaene Mercedes Ayuso Montserrat Guillen Dirk Van Gheel Guido Dedene 《European Journal of Operational Research》2007
Some property and casualty insurers use automated detection systems to help to decide whether or not to investigate claims suspected of fraud. Claim screening systems benefit from the coded experience of previously investigated claims. The embedded detection models typically consist of scoring devices relating fraud indicators to some measure of suspicion of fraud. In practice these scoring models often focus on minimizing the error rate rather than on the cost of (mis)classification. We show that focusing on cost is a profitable approach. We analyse the effects of taking into account information on damages and audit costs early on in the screening process. We discuss several scenarios using real-life data. The findings suggest that with claim amount information available at screening time detection rules can be accommodated to increase expected profits. Our results show the value of cost-sensitive claim fraud screening and provide guidance on how to render this strategy operational. 相似文献