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1.
We consider the problem of sending a message from a sender to a receiver through an unreliable network by specifying in a protocol what each vertex is supposed to do if it receives the message from one of its neighbors. A protocol for routing a message in such a graph is finite if it never floods with an infinite number of copies of the message. The expected reliability of a given protocol is the probability that a message sent from reaches when the edges of the network fail independently with probability .We discuss, for given networks, the properties of finite protocols with maximum expected reliability in the case when is close to 0 or 1, and we describe networks for which no one protocol is optimal for all values of . In general, finding an optimal protocol for a given network and fixed probability is challenging and many open problems remain. 相似文献
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Janina Kabatc 《Journal of polymer science. Part A, Polymer chemistry》2017,55(9):1575-1589
A radical initiation ability of new initiating systems in photopolymerization of 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol triacrylate has been investigated and presented. The evaluation of alkyltriphenyl‐ and tetraalkylborates, iodonium salts, N‐alkoxypyridinium salts, maleimides, phthalimides, 1,3,5‐triazine derivatives and others as a free radical source in combination with suitable photosensitizer for radical polymerization of triacrylate is described. It is assumed that the photochemical decomposition of a coinitiator molecule results in formation of free radicals, which further initiate polymerization. The order of activity of free radical sources on kinetic of photopolymerization was also presented. Different initiator activity can be explained by the difference in the decomposition rate constant and the reactivity of radicals formed toward the double bond of monomer. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1575–1589 相似文献
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Janina Möker Ursula Salge-Bartels Joachim Thiem 《Journal of carbohydrate chemistry》2013,32(9):702-710
Syntheses of carbohydrate-functionalized platinum complexes resembling presently employed cytostatics were performed. Mono-allylated sugar substrates obtained in two steps from glucose and galactose were connected with 2-allyl diethyl malonate by cross-metathesis. Following hydrogenation and acidic cleavage of the ester and alkylidene functionalities gave dicarboxylated glycoconjugates, which were transformed into their diammine platinum complexes. The antitumor activities of these platinum complexes were checked by sensitivity testing with 11 lung cancer cell lines. The novel glucose-platinum complex proved to be comparable to the drug carboplatin. 相似文献
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Philipp Rotering Lukas F. B. Wilm Janina A. Werra Dr. Fabian Dielmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(2):406-411
Electron-rich tertiary phosphines are valuable species in chemical synthesis. However, their broad application as ligands in catalysis and reagents in stoichiometric reactions is often limited by their costly synthesis. Herein, we report the synthesis and properties of a series of phosphines with 1-alkylpyridin-4-ylidenamino and 1-alkylpyridin-2-ylidenamino substituents that are accessible in a very short and scalable route starting from commercially available aminopyridines and chlorophosphines. The determination of the Tolman electronic parameter (TEP) value reveals that the electron donor ability can be tuned by the substituent pattern at the aminopyridine backbone and it can exceed that of common alkylphosphines and N-heterocyclic carbenes. The potential of the new phosphines as strong nucleophiles in phosphine-mediated transformations is demonstrated by the formation of Lewis base adducts with CO2 and CS2. In addition, the coordination chemistry of the new phosphines towards CuI, AuI, and PdII metal centers has been explored, and a convenient procedure to introduce the most basic phosphine into metal complexes starting from air-stable phosphonium salt is described. 相似文献
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Janina A. Werra Marius A. Wünsche Patrick Rathmann Paul Mehlmann Pawel Löwe Fabian Dielmann 《无机化学与普通化学杂志》2020,646(13):794-799
Phosphoniumylidyl and phosphazenyl groups are effective substituents to increase the electron-donating ability of tertiary phosphines. However, the influence of structural variations among those substituents on the electronic properties of the phosphines is little explored. Herein, we show that protonation of the ylidic carbon atom of phosphoniumylidyl phosphines increases the Tolman electronic parameter (TEP) by ΔTEP = 16.0–18.8 cm–1. Furthermore, phosphazenyl phosphines were synthesized with isopropyl groups (NP{iPr}3) and tetramethylguanidino groups (NP{tmg}3) at the phosphonium center. Determination of their TEP values reveals a remarkable low substituent parameter of χ = –18.5 cm–1 for the NP(tmg)3 group. In addition, we prepared the corresponding gold(I) complexes and determined their solid-state structures using single-crystal X-ray diffraction studies to analyze the steric profile of the new phosphine ligands. 相似文献
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Abstract The synthesis of nucleoside cyclic 3′,5′-phosphorofluoridates, so far not described compounds in the chemical literature, have been performed. As a key substrate we used 2′-deoxyribonucleoside cyclic 3′,5′-phosphorothioates (1) which have been obtained in this Laboratory several years ago.1 相似文献