Data Mining - Concepts and Techniques.

How to Do Things With Words

Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO2 emissions in the atmosphere demands that holding atmospheric CO2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.

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Powering the planet: Chemical challenges in solar energy utilization

語用論(Pragmatics)を考える

The site-selective formation of carbon-carbon bonds through direct functionalizations of otherwise unreactive carbon-hydrogen bonds constitutes an economically attractive strategy for an overall streamlining of sustainable syntheses. In recent decades, intensive research efforts have led to the development of various reaction conditions for challenging C-H bond functionalizations, among which transition-metal-catalyzed transformations arguably constitute thus far the most valuable tool. For instance, the use of inter alia palladium, ruthenium, rhodium, copper, or iron complexes set the stage for chemo-, site-, diastereo-, and/or enantioselective C-H bond functionalizations. Key to success was generally a detailed mechanistic understanding of the elementary C-H bond metalation step, which depending on the nature of the metal fragment can proceed via several distinct reaction pathways. Traditionally, three different modes of action were primarily considered for CH bond metalations, namely, (i) oxidative addition with electronrich late transition metals, (ii) σ-bond metathesis with early transition metals, and (iii) electrophilic activation with electrondeficient late transition metals (Scheme 1). However, more recent mechanistic studies indicated the existence of a continuum of electrophilic, ambiphilic, and nucleophilic interactions. Within this continuum, detailed experimental and computational analysis provided strong evidence for novel C-H bond metalationmechanisms relying on the assistance of a bifunctional ligand bearing an additional Lewis-basic heteroatom, such as that found in (heteroatom-substituted) secondary phosphine oxides or most prominently carboxylates (Scheme 1, iv). This novel insight into the nature of stoichiometric metalations has served as stimulus for the development of novel transformations based on cocatalytic amounts of carboxylates, which significantly broadened the scope of C-H bond functionalizations in recent years, with most remarkable progress being made in palladiumor ruthenium-catalyzed direct arylations and direct alkylations. These carboxylate-assisted C-H bond transformations were mostly proposed to proceed via a mechanism in which metalation takes place via a concerted base-assisted deprotonation. To mechanistically differentiate these intramolecular metalations new acronyms have recently been introduced into the literature, such as CMD (concerted metalationdeprotonation), IES (internal electrophilic substitution), or AMLA (ambiphilic metal ligand activation), which describe related mechanisms and will be used below where appropriate. This review summarizes the development and scope of carboxylates as cocatalysts in transition-metal-catalyzed C-H functionalizations until autumn 2010. Moreover, experimental and computational studies on stoichiometric metalation reactions being of relevance to the mechanism of these catalytic processes are discussed as well. Mechanistically related C-H bond cleavage reactions with ruthenium or iridium complexes bearing monodentate ligands are, however, only covered with respect to their working mode, and transformations with stoichiometric amounts of simple acetate bases are solely included when their mechanism was suggested to proceed by acetate-assisted metalation.

Carboxylate-assisted transition-metal-catalyzed C-H bond functionalizations: mechanism and scope.

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ProGraML: A Graph-based Program Representation for Data Flow Analysis and Compiler Optimizations

Tri-tert-butylphosphatetrahedrane (1) is shown here to act as a synthon of isomeric tri-tert-butylphosphacyclobutadiene in the presence of a Lewis acid or transition-metal complex. When it is combined with a substoichiometric amount of triphenylborane, compound 1 forms a ladderane-type dimer of tri-tert-butylphosphacyclobutadiene in 72% isolated yield. Trapping of a generated intermediate was achieved by repeating the experiment in the presence of excess styrene (20 equiv) or ethylene (1 atm), and the corresponding [4 + 2] cycloadducts of tri-tert-butylphosphacyclobutadiene were isolated in 88% and 74% yields, respectively. The platinum complex (Ph3P)2Pt(C2H4) also reacts with 1 to form an orange η2 complex of tri-tert-butylphosphacyclobutadiene in 80% isolated yield. Additionally, we report a novel method for generating a phosphinidenoid species via fluoride-induced trimethylsilyl fluoride elimination, leading to an improved preparative procedure for 1 (182 mg, 33% isolated yield).

Dimerization and Cycloaddition Reactions of Transient Tri-tert-butylphosphacyclobutadiene Generated by Lewis Acid Induced Isomerization of Tri-tert-butylphosphatetrahedrane.

Reduction of mer-Cl3W(ODipp)3 with Na/Hg in the presence of P4 in toluene afforded the orange complex (η3-P3)W(ODipp)3 (δ = –156 ppm, 10 % isolated yield). Unlike the valence-isoelectronic anion [(η3-P3)Nb(ODipp)3]–, treatment with AsCl3 of the neutral (η3-P3)W(ODipp)3 did not transfer the cyclo-P3 ligand to generate AsP3. Instead, this complex underwent aryloxide ligand transfer to form the red complex (η3-P3)W(Cl)(ODipp)2(THF) (δ = –143 ppm, 32 % isolated yield).

Contrasting cyclo-P3 Ligand Transfer Reactivity of Valence-Isoelectronic Aryloxide Complexes [(P3)Nb(ODipp)3]– and [(P3)W(ODipp)3]

Résumé The collaboration of theoretical pragmaticians and psychologists of language has been of benefit to all parties. Linguistic phenomena have been a fruitful domain for psychological study, and the empirical data gathered in connection with these phenomena have provided theorycritical evidence beyond the reach of reflective intuition. In this review, we focus in particular on questions concerning the locus of scalar implicatures and their intrusion into the truth-conditions of the utterance, and on the use of generalised and ad hoc scales in drawing scalar inferences. We aim to demonstrate the utility of experimental approaches to these questions.

Scalar implicature: Theory, processing and acquisition.

Successful out-of-hospital cardiac arrest (OHCA) resuscitation relies upon effective team communication, which is evaluated as an aspect of non-technical skills. However, this communication has been largely neglected from a dialogue perspective. We propose addressing this issue by examining the structure of OHCA interaction and its characteristic dialogue features. We explore how speakers verbally signal and align their current states, and the possible trade-off between directness and politeness. Preliminary data suggests frequent use of Assertions in OHCA communication, as in other medical interactions, but that OHCA situations also involve distinctively high proportions of Action-directives. Current states are mostly signalled using explicit State-awareness utterances. Directives’ force is also mitigated by politeness features. We discuss how these findings advance our aim of understanding effective team communication in the OHCA context, and how future work might identify associations between linguistic behaviours and resuscitation outcomes.

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Christopher C. Cummins

Papers

ProGraML: A Graph-based Program Representation for Data Flow Analysis and Compiler Optimizations

Dimerization and Cycloaddition Reactions of Transient Tri-tert-butylphosphacyclobutadiene Generated by Lewis Acid Induced Isomerization of Tri-tert-butylphosphatetrahedrane.

Contrasting cyclo-P3 Ligand Transfer Reactivity of Valence-Isoelectronic Aryloxide Complexes [(P3)Nb(ODipp)3]– and [(P3)W(ODipp)3]

Scalar implicature: Theory, processing and acquisition.

Resuscitation procedures as multi-party dialogue