Über assoziierte lineare und lokalkonvexe Topologien

Certain properties E of linear topological or locally convex spaces induce a functor in the corresponding category, which assigns to every space (X,F) an associated topologyF ^E. The well-known notions of the coarsest barrelled topology stronger than a given locally convex topology or of the strongest locally convex topology weaker than a given linear topology are examples of this concept. In the first two parts of this paper we consider the problem, whether the above functors commute with other processes, such as forming products, linear and locally convex direct sums, inductive limits and completions. With help of two technical lemmas we prove in the third part, that every separated locally convex space is a quotient of a complete locally convex space, in which every bounded set has a finite dimensional linear span. This sharpens results of Y. Kōmura [12], M. Valdivia [18] and W.J. Wilbur [20].     

Electronic transport in graphene nanostructures on SiO2

We report two experiments on graphene nanostructures. The first was performed on a graphene nanoribbon, where the nature of electronic transport was investigated in detail. Electrons or holes are found to localize in pockets of the potential along the ribbon. Transport is governed by the joint action of localization and Coulomb interaction. The temperature-dependence of the conductance shows activated behavior at temperatures above a few Kelvin. The activation energy retraces the edges of Coulomb blockade diamonds found in nonlinear transport. In the second experiment the metallic tip of a low-temperature scanning force microscope was scanned above a graphene quantum dot. In addition to the familiar Coulomb blockade fringes, localized states are detected forming in the constrictions connecting the dot to source and drain.     

The impact of blood on liver metabolite profiling – a combined metabolomic and proteomic approach

Metabolomics has entered the well‐established omic sciences as it is an indispensable information resource to achieve a global picture of biological systems. The aim of the present study was to estimate the influence of blood removal from mice liver as part of sample preparation for metabolomic and proteomic studies. For this purpose, perfused mice liver tissue (i.e. with blood removed) and unperfused mice liver tissue (i.e. containing blood) were compared by two‐dimensional gas chromatography time of flight mass spectrometry (GC × GC‐TOFMS) for the metabolomic part, and by liquid chromatography tandem mass spectrometry (LC‐MS/MS) for the proteomic part. Our data showed significant differences between the unperfused and perfused liver tissue samples. Furthermore, we also observed an overlap of blood and tissue metabolite profiles in our data, suggesting that the perfusion of liver tissue prior to analysis is beneficial for an accurate metabolic profile of this organ. Copyright © 2013 John Wiley & Sons, Ltd.     

Phosphate-Phosphonate Rearrangement of Aliphatic Phosphates

Abstract

Phosphorylation of various aliphatic alcohols gives phosphates 1 which are deprotonated by sBuLi/TMEDA in diethyl ether, THF or hexane at ?78 °C. The organo-lithiurns 2 and 4 formed isornerize to α-hydroxy- phosphonates 3 and 5 (phosphate-phosphonate rearrangement^[1.2]     

The Gauge–Bethe Correspondence and Geometric Representation Theory

The Gauge/Bethe correspondence of Nekrasov and Shatashvili relates the spectrum of integrable spin chains to the ground states of supersymmetric gauge theories. Up to now, this correspondence has been an observation; the underlying reason for its existence remaining elusive. We argue here that geometrical representation theory is a mathematical foundation of the Gauge/Bethe correspondence, and it provides a framework to study families of gauge theories in a unified way.     

1H MRS detection of glycine residue of reduced glutathione in vivo

Glutathione (GSH) is a powerful antioxidant found inside different kinds of cells, including those of the central nervous system. Detection of GSH in the human brain using ¹H MR spectroscopy is hindered by low concentration and spectral overlap with other metabolites. Previous MRS methods focused mainly on the detection of the cysteine residue (GSH-Cys) via editing schemes. This study focuses on the detection of the glycine residue (GSH-Gly), which is overlapped by glutamate and glutamine (Glx) under physiological pH and temperature. The first goal of the study was to obtain the spectral parameters for characterization of the GSH-Gly signal under physiological conditions. The second goal was to investigate a new method of separating GSH-Gly from Glx in vivo. The characterization of the signal was carried out by utilization of numerical simulations as well as experiments over a wide range of magnetic fields (4.0–14 T). The proposed separation scheme utilizes J-difference editing to quantify the Glx contribution to separate it from the GSH-Gly signal. The presented method retains 100% of the GSH-Gly signal. The overall increase in signal to noise ratio of the targeted resonance is calculated to yield a significant SNR improvement compared to previously used methods that target GSH-Cys residue. This allows shorter acquisition times for in vivo human clinical studies.     

Versatile Organometallic Initiators for the Living Polymerization of Isocyanates

Shashoua and Sweeney first demonstrated that isocyanates could by polymerized via an anionic mechanism to form high molecular weight materials. We have sought to eliminate the problems associated with the anionic procedure by developing transition metal complexes which are capable of catalyzing the living polymerization of isocyanates. Recently, we reported the living polymerization of alkyl isocyanates using TiCl₃OCH₂CF₃, I. Using I, polyisocyanates with controlled molecular weights and narrow polydispersities can be obtained at room temperature. ε⁵-CpTiCl₂N(CH₃)₂ (Cp = cyclopentadienyl), III, is also an excellent catalyst for the polymerization of isocyanates, and in terms of ease of handling and purification and tolerance toward monomer functionality, superior to I. In order to prepare triblock copolymers containing amorphous segments sandwiched between two isocyanate segments, we have prepared bimetallic initiators comprised of titanium alkoxides con- nected by flexible linkers. These linkers may be a small molecule (1,4- dihydroxycyclohexane, V) or a polymer (polydimethylsiloxane, PDMS, VI). Complexes V and VI can be used to initiate the living polymerization of isocyanates to yield polymers possessing central cyclohexyl bends (ldquo;broken worms rdquo;) or PDMS segments (triblock copolymers), respectively. Finally, cyclopolymerizations of 1,2-diisocyanates using these or- ganometallic initiators are reported.     

Electron Transfer between Hydrogen‐Bonded Pyridylphenols and a Photoexcited Rhenium(I) Complex

Two pyridylphenols with intramolecular hydrogen bonds between the phenol and pyridine units have been synthesized, characterized crystallographically, and investigated by cyclic voltammetry and UV/Vis spectroscopy. Reductive quenching of the triplet metal‐to‐ligand charge‐transfer excited state of the [Re(CO)₃(phen)(py)]⁺ complex (phen=1,10‐phenanthroline, py=pyridine) by the two pyridylphenols and two reference phenol molecules is investigated by steady‐state and time‐resolved luminescence spectroscopy, as well as by transient absorption spectroscopy. Stern–Volmer analysis of the luminescence quenching data provides rate constants for the bimolecular excited‐state quenching reactions. H/D kinetic isotope effects for the pyridylphenols are on the order of 2.0, and the bimolecular quenching reactions are up to 100 times faster with the pyridylphenols than with the reference phenols. This observation is attributed to the markedly less positive oxidation potentials of the pyridylphenols with respect to the reference phenols (≈0.5 V), which in turn is caused by proton coupling of the phenol oxidation process. Transient absorption spectroscopy provides unambiguous evidence for the photogeneration of phenoxyl radicals, that is, the overall photoreaction is clearly a proton‐coupled electron‐transfer process.