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991.
Markus Schinhaerl Gordon Smith Richard Stamp Rolf Rascher Lyndon Smith Elmar Pitschke Peter Sperber Andreas Geiss 《Applied Mathematical Modelling》2008
Computer-controlled polishing (CCP) is commonly used to finish high-quality surfaces, such as optical lenses. Based on magnetorheological finishing (MRF), a mathematical model to calculate the polishing tool characteristic (influence function) was developed and verified experimentally. The first part of this paper introduces the model to predict the size and shape of an influence function. The second part of this paper describes the calculation of the distribution of material removal within the size of an influence function. The model supersedes the current cumbersome procedure for determining an influence function and thus results in considerably improved and more economical manufacture. Furthermore, the model enables the quality of the final surface to be enhanced when polishing complex, for example aspherical or free-form, workpiece geometries and provides the first step in the application of time-variant influence functions. 相似文献
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995.
Christian Slugovc Eva Rüba Roland Schmid Karl Kirchner Kurt Mereiter 《Monatshefte für Chemie / Chemical Monthly》2000,131(12):1241-1251
Summary. This article gives an overview of recent chemistry based on the tris-acetonitrile complex [RuCp(CH3CN)3]+. Due to the labile nature of the CH3CN ligands, substitution reactions are a dominant feature of this complex. Important derivatives are the highly reactive complexes
[RuCp(PR
3)(CH3CN)2]+ which are a source of the 14e− fragment [RuCp(PR
3)]+. These species are catalytically active in the redox isomerization of allyl alcohols to give aldehydes and ketones. Furthermore,
the cationic complex [RuCp(κ1(P),η2-PPh2CH2CH2CH*CH2)(CH3CN)]PF6 derived from the reaction of [RuCp(CH3CN)3]+ with PPh2CH2CH2CH*CH2 is a model compound for studying coupling reactions of olefins and acetylenes. In addition, [RuCp(CH3CN)3]+ is a valuable precursor for the synthesis of configurationally stable chiral three-legged piano-stool ruthenium complexes.
These are currently being intensively investigated as Lewis acid catalysts in asymmetric synthesis.
Received May 31, 2000. Accepted June 13, 2000 相似文献
996.
Toby Cubitt Aram W. Harrow Debbie Leung Ashley Montanaro Andreas Winter 《Communications in Mathematical Physics》2008,284(1):281-290
Complementing recent progress on the additivity conjecture of quantum information theory, showing that the minimum output
p-Rényi entropies of channels are not generally additive for p > 1, we demonstrate here by a careful random selection argument that also at p = 0, and consequently for sufficiently small p, there exist counterexamples.
An explicit construction of two channels from 4 to 3 dimensions is given, which have non-multiplicative minimum output rank;
for this pair of channels, numerics strongly suggest that the p-Rényi entropy is non-additive for all p ≲ 0.11. We conjecture however that violations of additivity exist for all p < 1. 相似文献
997.
Camilla Nilsson Eva Malmström Mats Johansson Stacy M. Trey 《Journal of polymer science. Part A, Polymer chemistry》2009,47(2):589-601
A series of well‐defined allyl‐ether functionalized polyester dendrimers has been synthesized via the divergent approach using traditional esterification reactions. Two commercially available trifunctional thiols, trimethylolpropane tri(3‐mercaptopropanoate) (TRIS) and ethoxylated trimethylolpropane tri(3‐mercaptopropanoate) (ETTMP), were incorporated with the dendrimers into the thiol‐ene polymer networks. The thiol‐ene reactions were conducted at room temperature and cured by UV light without the addition of photoinitiatior. Highly crosslinked films were obtained and characterized with respect to mechanical (DMA) and thermal (DSC and TGA) properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 589–601, 2009 相似文献
998.
Andreas Winter Christian Friebe Manuela Chiper Martin D. Hager Ulrich S. Schubert 《Journal of polymer science. Part A, Polymer chemistry》2009,47(16):4083-4098
A series of main‐chain metallopolymers ( P1–P10 ) was prepared by the self‐assembly of rigid‐linear π‐conjugated bis(terpyridine) monomers ( 1–10 ) with ZnII ions and was fully characterized. The polymerization was additionally confirmed by UV/vis titration experiments. A strong increase in viscosities (around 1.6 times) relative to those of the monomer solutions was found. The thermal stability of P1–P10 compared with that of 1–10 was enhanced as a result of the metallopolymerization. The electro‐optical properties of the materials were investigated in detail. Tuning of the electrochemical and photophysical properties was enabled; thus, bright purple to green photoluminescent (PL) emission (PL quantum yields of 0.12–0.81) for P1–P10 was observed in solution with the emission color strongly depending on the nature of the π‐conjugated bis(terpyridine) system. Thin homogeneous films of P6 were prepared by solution processing, that is, spin‐coating and inkjet‐printing, and exhibited intense yellow PL emission in the solid state. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4083–4098, 2009 相似文献
999.
Marianne Gaborieau Hank De bruyn Siyabonga Mange Patrice Castignolles Andreas Brockmeyer Robert G. Gilbert 《Journal of polymer science. Part A, Polymer chemistry》2009,47(7):1836-1852
A method is developed for anchoring enzymatically degraded cationized starch as electrosteric stabilizers onto synthetic latices, using cerium(IV) to create free‐radical grafting sites on the starch. Direct anchoring of debranched starch onto a poly(methyl methacrylate) seed latex yields a latex stabilized by well‐defined oligosaccharides. Using α‐amylase to randomly cleave starch to form (1→4)‐α‐glucans, and a comonomer, N‐isopropyl acrylamide (NIPAM), whose corresponding polymer exhibits a lower critical solution temperature (LCST), creates a means to synthesize block (or graft) oligomers of oligosaccharide and synthetic polymer, which are water soluble at room temperature. Above 30 °C, they become amphiphilic and form self‐emulsifying nanoparticles (sometimes termed “frozen micelles”) from which a synthetic latex is grown after addition of methyl methacrylate, the collapsed NIPAM‐containing entities functioning as a type of in situ seed. This synthesis of stable synthetic latex particles is shown to have a high grafting efficiency. The starch fragments were characterized by 1H solution‐state NMR before grafting, and 13C solid‐state cross‐polarization magic‐angle spinning (CP‐MAS) NMR was used to characterize the starch oligomers actually grafted on the final latex. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1836–1852, 2009 相似文献
1000.
Camilla Nilsson Neil Simpson Michael Malkoch Mats Johansson Eva Malmström 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1339-1348
Well‐defined, allyl‐ether functional, first‐generation dendrimers have been synthesized. The convergent growth approach was utilized, using the anhydride of the allyl‐ether terminated building block. Three different core moieties were used: trimethylolpropane, trisphenol, and ditrimethylolpropane. The coupling reactions proceeded in good yields and all compounds were characterized by NMR, MALDI‐TOF, and SEC. The allyl‐terminated dendrimers were crosslinked by thiol–ene chemistry, using a multifunctional thiol, TriThiol, to give clear and smooth films. The photopolymerization was conducted in the presence of a photoinitiator, Irgacure 651, and no traces of either allyl‐ether groups or thiols were observed by FT‐Raman after cure. All crosslinked films were characterized with respect to mechanical (DMA) and thermal (DSC) properties. It was found that homogeneous networks were formed and that the core functionality and structure had little effect on the network properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1339–1348, 2008 相似文献