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Summary We present the results of several surveys for supernovae (SNe) in galaxy clusters. SNe discovered in deep, archival HST images were used to measure the cluster SN Ia rate to z = 1. A search for SNe in nearby (0.06 ≤ z ≤ 0.2) Abell galaxy clusters yielded 15 SNe, 12 of which were spectroscopically confirmed. Of these, 7 are cluster SNe Ia, which we will use to measure the SN Ia rate in nearby clusters. This search has also discovered the first convincing examples of intergalactic SNe. We conclude with a brief description of ongoing and future cluster SN surveys.
We extend the notion of memristive systems to capacitive and inductive elements, namely capacitors and inductors whose properties depend on the state and history of the system. All these elements show pinched hysteretic loops in the two constitutive variables that define them: current-voltage for the memristor, charge-voltage for the memcapacitor, and current-flux for the meminductor. We argue that these devices are common at the nanoscale where the dynamical properties of electrons and ions are likely to depend on the history of the system, at least within certain time scales. These elements and their combination in circuits open up new functionalities in electronics and they are likely to find applications in neuromorphic devices to simulate learning, adaptive and spontaneous behavior.
This chapter contains sections titled: Introduction The Formation of Compounds Containing Transition-metal–Silicon Bonds Late Transition-metal Derivatives Methods Involving Oxidative Addition of SiH Bonds Methods Involving Oxidative Addition of Other SiX Bonds Methods Employing Transition-metal Anions Methods Employing Main-group Metal Silyl Compounds Miscellaneous Methods Transition-metal Silicon Clusters Early Transition-metal Derivatives Methods Employing Main-group Metal Silyl Compounds Methods Involving Cleavage of SiH Bonds Related F-element Derivatives Transition-metal Silylene Complexes Indirect Evidence for Coordinated Silylenes Attempted Preparations Transition-metal Silene Complexes Structure and Bonding Structural Information Metal–silicon Bond Distances Other Structural Features Information from NMR Studies Information from Infrared and Raman Studies Information from Mass Spectrometric Studies Reactions Involving MSi Bonds Cleavage of MSi Bonds by Nucleophiles Cleavage of MSi Bonds by Electrophiles Cleavage of MSi Bonds by Other Reagents Insertion Reactions Insertion of Alkenes Insertion of Alkynes Insertion of Nitriles Insertion of Organic Carbonyl Compounds Insertion of Carbon Monoxide and Isocyanides Catalytic Reactions Hydrosilylation Dehydrogenative Coupling Reactions Involving Hydrosilanes Redistribution on Silicon Other SiC Bond-forming Reactions Catalytic Reactions with Hydrosilanes and Carbon Monoxide References
This is the executive summary of Dagstuhl Seminar 06131, "Peer-to-Peer-Systems and -Applications". The seminar was held from March 26th to March 29th, 2006, at the International Conference and Research Center for Computer Science at Castle Dagstuhl, Germany.
Abstract The crosslinking chemistry of a new elastomer based on brominated poly(isobutylene‐co‐4‐methylstyrene) has been investigated using model compounds. In order to mimic the conditions that prevail within the highly allphatic rubber, the study was carried out in mineral oil using catalysts that are compatible with such low polarity media. Electrophilic aromatic substitution reactions occur in a system consisting of p ‐isopropylbenzyl bromide and p ‐isopropyl toluene in the presence of zinc oxide and zinc stearate. The reaction proceeds after a significant induction period while no induction period is seen for a similar reaction with zinc bromide as the catalyst. The in situ formation of reactive species containing ZnBr bonds appears to be an important step in the overall process. The stoichiometric ratio of zinc salt to benzylic bromide is important. High ratios lead to the accumulation of benzylic stearate or benzylic alcohol in the system which retards the alkylation reaction. The model study emphasizes the importance of stoichiometry of reagents in this reaction and provides insight into the crosslinking mechanism. © 1993 John Wiley & Sons, Inc.
Copper is all bound up: The copper-catalyzed α-arylation of carbonyl compounds occurs through oxidative addition of iodoarenes to the C-bound CuI enolate species 1 to form an aryl–CuIII intermediate (see scheme). Computational results provide insight into the origins of the relative reactivity of various CuI enolate complexes in the reactions with iodoarenes. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
We introduce a new type of metallo-dielectric photonic band gap structure (PBG), intentionally incorporating very strong capacitive interactions between the periodic metallic islands. The band gaps become huge, with the lower band edge frequency being pushed down by the capacitive interaction between metallic islands, while the upper band edge frequency continues to depend primarily on the lattice constant, as in normal PBG's. With this new type of photonic crystal, the spatial periodicity can be much smaller than the corresponding electromagnetic wavelength, allowing PBG structures to play a role at radio frequencies.
