Topology of Earth's climate indices and phase-locked states

Phase-locked states in Earth's climate system were identified in a study of a set of climate indices by Swanson and Tsonis (2009) [1] (ST). They reported five climate shift events since 1900 based upon features in a phase-locking parameter S. The present study finds that sets of climate indices have important topological properties such as a metric diameter D that describes the magnitude of phase locking among the indices. Minima in D as a function of time are shown to be associated with climate shifts. Eighteen strong events since 1870 are identified, including the five reported by ST. Ten of these minima correspond to reported events such as the well documented “climate shift of the mid-1970s” and the more recent climate shift of 2001-2002. Most climate shifts tend toward radiative equilibrium.     

Manipulation and capture of Aβ amyloid fibrils and monomers by DC insulator gradient dielectrophoresis (DC-iGDEP)

Here we report a novel method for the manipulation and concentration of Aβ amyloid fibrils, implicated in Alzheimer's disease, using DC insulating gradient dielectrophoresis (DC-iGDEP). Fibril enrichment was found to be ～400%. Simulations suggest that capture of the full range of amyloid protein aggregates is possible with optimized device design.     

A piperidine chiron for the Veratrum alkaloids

A Veratrum piperidine chiron was prepared over 11 steps (7.9% yield) from (-)-citronellal. Three methods for the installation of the propargylic side chain onto a cyclic enamide are presented.     

Potassium hydride in paraffin: a useful base for organic synthesis

The preparation of potassium hydride as a 1:1 homogenate with paraffin, termed KH(P), is reported. KH(P), a solid at room temperature, is stable without special handling. On suspension in THF with a phosphonium salt, KH(P) rapidly generates the ylide. Wittig condensation with aromatic, aliphatic, and alpha,beta-unsaturated aldehydes proceeds with high Z selectivity. KH(P) should be a generally useful base for organic synthesis.     

Synthesis of (-)-Astrogorgiadiol

Astrogorgiadiol is a naturally occurring Vitamin D analogue that, in cell culture, downregulates the production of the cytokine osteopontin (OPN). OPN has been implicated in virulent asthma, and OPN knockout mice do not develop osteoporosis. As we have pursued whole animal studies with astrogorgiadiol, we have increased the scale of the synthesis. We report an improved preparation of the A-ring synthon and the scale-up of the diasteromerically pure D-ring/sidechain chiron.     

Practical Enzymatic Production of Carbocycles

The Pd-catalyzed carbon-carbon bond formation pioneered by Heck in 1969 has dominated medicinal chemistry development for the ensuing fifty years. As the demand for more complex three-dimensional active pharmaceuticals continues to increase, preparative enzyme-mediated assembly, by virtue of its exquisite selectivity and sustainable nature, is poised to provide a practical and affordable alternative for accessing such compounds. In this minireview, we summarize recent state-of-the-art developments in practical enzyme-mediated assembly of carbocycles. When appropriate, background information on the enzymatic transformation is provided and challenges and/or limitations are also highlighted.     

Reductiveversus coupling pathways in the reactions of nickel and copper vapours with the mono-halobenzenes

Summary The reactions of nickel and copper vapours with mono-halobenzenes to form benzene and biphenyl are reported. Benzene formation apparently proceeds through the intermediacy of the phenyl radical, which is produced when metal clusters abstract halogen from the halobenzene. Biphenyl formation proceedsvia an oxidative insertion/disproportionation/reductive elimination sequence, and requires that metal atoms, rather than metal clusters, initiate the reaction sequence. The concentration of the metal in the matrix determines the pathway of the reaction. Cluster formation and benzene production are favouted by high metal concentrations, while low metal concentrations in the matrix favour biphenyl production. Copper vapours are anomalously less reactive than nickel vapours, even though copper reagents are used in the Ullmann reaction to produce biaryls through the coupling of haloarenes. This result appears to be due to the preferential formation of atoms or very small clusters over large clusters or crystallites under the conditions of the metal vapour synthesis technique.     

Curing of monomer composites, 2. The use of NMR to monitor real time curing dynamics

A novel method is described for monitoring the real‐time curing dynamics of composite monomers, exploiting site specific information provided by high resolution NMR. Important temporal information is encoded in the component lineshapes and intensities of ¹H and ¹³C NMR spectra recorded as a function of curing time. A computed simulation based on a (Q‐e)‐multicomponent kinetic model matches experimental data well, which lends confidence to the model when used in a predictive mode.     

The Steinberg variety and representations of reductive groups

We give an overview of some of the main results in geometric representation theory that have been proved by means of the Steinberg variety. Steinberg's insight was to use such a variety of triples in order to prove a conjectured formula by Grothendieck. The Steinberg variety was later used to give an alternative approach to Springer's representations and played a central role in the proof of the Deligne–Langlands conjecture for Hecke algebras by Kazhdan and Lusztig.     

Enantioselective conjugate allylation of cyclic enones

Enantioselective organocatalytic 1,2-allylation of a cyclic enone followed by anionic oxy-Cope rearrangement delivered the ketone as a mixture of diastereomers. This appears to be a general method for the net enantioselective conjugate allylation of cyclic enones.