Imaging the Hydrated Microbe‐Metal Interface Using Nanoscale Spectrum Imaging

PdAu nanocrystals are synthesised by Geobacter sulfurreducens, a dissimilatory metal‐reducing bacterium, and the resulting bimetallic nanocrystal‐decorated microbes are imaged using a range of advanced electron microscopy techniques. Specifically, the first example of elemental mapping of fully hydrated biological nanostructures using scanning transmission electron microscope (STEM) energy dispersive X‐ray (EDX) spectrum imaging within an environmental liquid‐cell is reported. These results are combined with cryo‐TEM and ex situ STEM imaging and EDX analysis with the aim of better understanding microbial synthesis of bimetallic nanoparticles. It is demonstrated that although Au and Pd are colocalized across the cells, the population of nanoparticles produced is bimodal, containing ultrasmall alloyed nanocrystals with diameters <3 nm and significantly larger core‐shell structures (>200 nm in diameter) which show higher Pd contents and exhibit a Pd enriched shell only a few nanometers thick. The application of high‐resolution imaging techniques described here offers the potential to visualize the microbe‐metal interface during the bioproduction of a range of functional materials by microbial “green” synthesis routes, and also key interfaces underpinning globally relevant environmental processes (e.g., metal cycling).     

The synthesis and characterisation of europium terpyridine-N-oxide complexes

Europium complexes of a series of terpyridine-N-oxide ligands have been prepared and structurally characterised by crystallographic studies. While the addition of three equivalents of terpyridine-1-oxide or terpyridine-1,1'-bisoxide results in complexes with nine co-ordinate tricapped trigonal prismatic or monocapped square antiprismatic geometries, respectively, three equivalents of the terpyridine-1,1',1'-trisoxide yields an unexpected 8 co-ordinate geometry. Luminescence studies of the three complexes in acetonitrile show a typical europium emission spectra, dominated by the (5)D(0)-(7)F(2) transition. While no simple trend in the relative quantum yields could be ascertained, the terpyridine-1-oxide complex was observed to have the most intense luminescence for this set of complexes.     

Proton magnetic resonance of planar condensed benzenoid hydrocarbons

Second-order, iterative analyses of the P.M.R. spectra of 15 different unsubstituted, condensed, benzenoid hydrocarbons are reported; all the spectra dealt with have been obtained in a common, isotropic solvent (CCl₄), and the chemical shifts they afforded have, where solubility permitted, been individually extrapolated to infinite dilution. More coupling constant data have been derived to test an earlier empirical equation, and discrepancies for overcrowded protons, observed previously, are confirmed. Dilution effects are discussed and it is concluded that a systematic comparison of experimental and theoretically calculated chemical shifts can be made reliably only when the experimental shifts have all been obtained by iterative, second-order analysis at (or near) infinite dilution, in a common, isotropic solvent.     

Proton magnetic resonance of non-planar condensed benzenoid hydrocarbons

The spectra of the title compounds have been analysed iteratively by computer, and chemical shifts and coupling constants have been determined at infinite dilution (or very low concentration) in carbon tetrachloride. The ortho coupling constants are compared with an empirical equation. The effect of concentration on chemical shifts is qualitatively related to inter-molecular ‘ring current’ effects. The chemical shifts at infinite dilution are to be compared with a new theory in the next paper [7].     

Set the controls for the heart of the Sun

In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required.     

Synthesis and structure of [[MeAl(mu-PMes)(PMes)]2Li4]2 x 7thf,containing a [MeAl(mu-PMes)(PMes)]2(4-) tetraanion (Mes = 2,4,6-Me3C6H2)

The reaction of MeAlCl2 with MesPHLi (1:4 equivalents) in thf/toluene gives the cage complex [[MeAl(mu-PMes)(PMes)]2Li4]2 x 7thf (1), containing an [[MeAl(mu-PMes)(PMes))2]4- tetraanion which is valence-isoelectronic with extensively studied Group 15 anions of the type [E(mu-NR)(NR)]2(2-).     

Selective small molecule inhibitors of glycogen synthase kinase-3 modulate glycogen metabolism and gene transcription

BACKGROUND: Glycogen synthase kinase-3 (GSK-3) is a serine/threonine protein kinase, the activity of which is inhibited by a variety of extracellular stimuli including insulin, growth factors, cell specification factors and cell adhesion. Consequently, inhibition of GSK-3 activity has been proposed to play a role in the regulation of numerous signalling pathways that elicit pleiotropic cellular responses. This report describes the identification and characterisation of potent and selective small molecule inhibitors of GSK-3. RESULTS: SB-216763 and SB-415286 are structurally distinct maleimides that inhibit GSK-3alpha in vitro, with K(i)s of 9 nM and 31 nM respectively, in an ATP competitive manner. These compounds inhibited GSK-3beta with similar potency. However, neither compound significantly inhibited any member of a panel of 24 other protein kinases. Furthermore, treatment of cells with either compound stimulated responses characteristic of extracellular stimuli that are known to inhibit GSK-3 activity. Thus, SB-216763 and SB-415286 stimulated glycogen synthesis in human liver cells and induced expression of a beta-catenin-LEF/TCF regulated reporter gene in HEK293 cells. In both cases, compound treatment was demonstrated to inhibit cellular GSK-3 activity as assessed by activation of glycogen synthase, which is a direct target of this kinase. CONCLUSIONS: SB-216763 and SB-415286 are novel, potent and selective cell permeable inhibitors of GSK-3. Therefore, these compounds represent valuable pharmacological tools with which the role of GSK-3 in cellular signalling can be further elucidated. Furthermore, development of similar compounds may be of use therapeutically in disease states associated with elevated GSK-3 activity such as non-insulin dependent diabetes mellitus and neurodegenerative disease.