(CF(3))(4)Au(2)(C(5)H(5)N)(2)] - a new alkyl gold(ii) derivative with a very short Au-Au bond

A new gold(ii) species [(CF(3))(4)Au(2)(C(5)H(5)N)(2)] with a very short unsupported Au-Au bond (250.62(9) pm) was generated by photo irradiation of a silver aurate, [Ag(Py)(2)][Au(CF(3))(2)], unambiguously characterized by (19)F and (109)Ag NMR studies.     

Thermo-IR-spectroscopy study of the adsorption of terbuthylazine by soil from the Jezreel Valley

Adsorption of the herbicide terbuthylazine by a soil from the Jezreel Valley was investigated by thermo-IR-spectroscopy. The adsorption took place mainly by the clay mineral montmorillonite. The adsorbed molecule was hydrogen bonded via the aniline groups to water molecules which were coordinated to the exchangeable metallic cations. When the sample was thermally treated at 115°C interlayer water was evolved, part of the herbicide decomposed and the other part became directly coordinated to the exchangeable metallic cations. The decomposition product contained a CO group.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthdayThis research was supported in part under Project number C12-219, Grant number HRN5544 G002069, Program in Science and Technology Corporation, Human Capacity Development, Bureau for Global Programs, Field Support and Research, USAID.     

Chiral Chalcogenyl-Substituted Naphthyl- and Acenaphthyl-Silanes and Their Cations

Cyclic silylated chalconium borates 13 [B(C₆F₅)₄] and 14 [B(C₆F₅)₄] with peri-acenaphthyl and peri-naphthyl skeletons were synthesized from unsymmetrically substituted silanes 3 , 4 , 6 , 7 , 9 and 10 using the standard Corey protocol (Chalcogen Ch=O, S, Se, Te). The configuration at the chalcogen atom is trigonal pyramidal for Ch=S, Se, Te, leading to the formation of cis- and trans-isomers in the case of phenylmethylsilyl cations. With the bulkier tert-butyl group at silicon, the configuration at the chalcogen atoms is predetermined to give almost exclusively the trans-configurated cyclic silylchalconium ions. The barriers for the inversion of the configuration at the sulfur atoms of sulfonium ions 13 c and 14 a are substantial (72–74 kJ mol⁻¹) as shown by variable temperature NMR spectroscopy. The neighboring group effect of the thiophenyl substituent is sufficiently strong to preserve chiral information at the silicon atom at low temperatures.     

Coronenohelicenes with Dynamic Chirality

The synthesis of a new type of chiral and dynamic nonplanar aromatics containing a combination of fused perylene-based coronenes and helicenes is reported. Either one or two helicene moieties were fused to the bay regions of an extended perylene core. The target compounds contain either identical or two different helicene building blocks. The combination with two helicene units leads to six different isomers, including two pairs of enantiomers and two meso forms. The experimental determination of the isomerization barriers the corresponding double [5]-helicenes revealed activation energies of E_a=24.81 and 25.38 kcal mol⁻¹, which is slightly above the barrier of the parent [5]-helicene. Resolution of all possible regio- and stereoisomers allowed for the systematic investigation of the chiroptical properties. They revealed remarkable dissymmetry factors Ig_absI of up to 1.2×10⁻², which mirror the synergy between the strong absorbing perylenes and the inherent chirality of helicenes.     

Biomarker Candidates of <Emphasis Type="Italic">Chlamydophila pneumoniae</Emphasis> Proteins and Protein Fragments Identified by Affinity-Proteomics Using FTICR-MS and LC-MS/MS

We report here an affinity-proteomics approach that combines 2D-gel electrophoresis and immunoblotting with high performance mass spectrometry to the identification of both full length protein antigens and antigenic fragments of Chlamydophila pneumoniae (C. pneumoniae). The present affinity-mass spectrometry approach effectively utilized high resolution FTICR mass spectrometry and LC-tandem-MS for protein identification, and enabled the identification of several new highly antigenic C. pneumoniae proteins that were not hitherto reported or previously detected only in other Chlamydia species, such as Chlamydia trachomatis. Moreover, high resolution affinity-MS provided the identification of several neo-antigenic protein fragments containing N- and C-terminal, and central domains such as fragments of the membrane protein Pmp21 and the secreted chlamydial proteasome-like factor (Cpaf), representing specific biomarker candidates.     

Slow quench dynamics of a one-dimensional Bose gas confined to an optical lattice

We analyze the effect of a linear time variation of the interaction strength on a trapped one-dimensional Bose gas confined to an optical lattice. The evolution of different observables such as the experimentally accessible on site particle distribution are studied as a function of the ramp time by using time-dependent numerical techniques. We find that the dynamics of a trapped system typically displays two regimes: For long ramp times, the dynamics is governed by density redistribution, while at short ramp times, local dynamics dominates as the evolution is identical to that of an homogeneous system. In the homogeneous limit, we also discuss the nontrivial scaling of the energy absorbed with the ramp time.     

The impedance caused by interfacial current constriction: a case study on BaF2/YSZ bicrystals

Abstract  

BaF₂/YSZ (yttria stabilized zirconia) bicrystals are investigated by means of impedance spectroscopy. The spectra show two semicircles in the complex impedance plane, and both arcs exhibit very similar temperature dependences. The high frequency semicircle can be attributed to the ideal (quasi one-dimensional) bulk resistance of BaF₂, and the low frequency arc is caused by an additional resistance in BaF₂ due to the current constriction taking place close to the contact spots at the imperfect bicrystal interface. This interpretation is supported by finite element calculations revealing that bicrystals with imperfect contacts indeed exhibit an additional semicircle in the complex impedance plane even without any ion transfer resistance between the two crystals. The low frequency arc of the BaF₂/YSZ bicrystal drastically increases upon bias voltage, but relaxes to its original value after removing the bias. This phenomenon can be associated with a strong decrease of the vacancy concentration in YSZ (close to the interfacial contact spots), which is caused by F⁻ ions being pumped into YSZ and acting as a counter dopant to Y³⁺.     

Simple device for dissolution and sample transfer for applications in spin-hyperpolarization

ABSTRACT

Rapid dissolution and transfer of samples are crucial steps in hyperpolarization methods such as dissolution dynamic nuclear polarization (dDNP) and quantum-rotor-induced polarization (QRIP). Here we introduce a simple and modular dissolution transfer device, and we demonstrate its application for QRIP. This device operates with low pressures and solvent volumes compared to state-of-the-art dDNP setups. On the other hand, transfer times are longer, although sufficient for ¹³C NMR spectroscopy. Our approach does not require an additional cryostat.