Alignment of plate-like particles in a colloidal dispersion under flow in a uniform pipe studied by high-energy X-ray diffraction

High-energy angle-dispersive X-ray diffraction has been used to study the alignment of colloidal suspension of kaolinite particles in water as they flow along a pipe. X-rays with energies above 25 keV have a major advantage, as they can penetrate through thick samples and walls of containers and permit investigation of samples under realistic flow conditions. As an example of the method, flow through a circular cross-section pipe with an internal diameter of 5 mm has been studied: this is typical of industrial applications. The angular distribution of intensities of peaks in the diffraction pattern as a function of the location of the pipe in the X-ray beam provides information about the alignment of particles under flow. Order parameters have been calculated to describe the alignment and direction of orientation. It is observed that the particles align in the direction of flow with their flat faces parallel to the flow. The experimental results are compared with the calculations of the local strain rate that help to explain the onset of alignment of the particles.     

Structural characterization of a copper nitrosyl complex with a {CuNO}10 configuration

The synthesis and characterization of a {CuNO}(10) complex, namely, [Cu(CH(3)NO(2))(5)(NO)][PF(6)](2), has been achieved by the addition of [NO][PF(6)] to copper metal powder in the presence of nitromethane. In the solid state, this complex exhibits a bent Cu-N-O moiety [Cu-N-O = 121.0(3)°] and a long Cu-N bond. This complex readily reacts with mesitylene to form [mesitylene, NO][PF(6)] and [Cu(η(2)-1,3,5-Me(3)C(6)H(3))(2)][PF(6)] by transfer of NO(+) to the mesitylene ring.     

Rapid fabrication of glass/PDMS hybrid µIMER for high throughput membrane proteomics

Mass spectrometry (MS) based proteomics has brought a radical approach to systems biology, offering a platform to study complex biological functions. However, key proteomic technical challenges remain, mainly the inability to characterise the complete proteome of a cell due to the thousands of diverse, complex proteins expressed at an extremely wide concentration range. Currently, high throughput and efficient techniques to unambiguously identify and quantify proteins on a proteome-wide scale are in demand. Miniaturised analytical systems placed upstream of MS help us to attain these goals. One time-consuming step in traditional techniques is the in-solution digestion of proteins (4-20 h). This also has other drawbacks, including enzyme autoproteolysis, low efficiency, and manual operation. Furthermore, the identification of α-helical membrane proteins has remained a challenge due to their high hydrophobicity and lack of trypsin cleavage targets in transmembrane helices. We demonstrate a new rapidly produced glass/PDMS micro Immobilised Enzyme Reactor (μIMER) with enzymes covalently immobilised onto polyacrylic acid plasma-modified surfaces for the purpose of rapidly (as low as 30 s) generating peptides suitable for MS analysis. This μIMER also allows, for the first time, rapid digestion of insoluble proteins. Membrane protein identification through this method was achieved after just 4 min digestion time, up to 9-fold faster than either dual-stage in-solution digestion approaches or other commonly used bacterial membrane proteomic workflows.     

Superflow in a toroidal Bose-Einstein condensate: an atom circuit with a tunable weak link

We have created a long-lived (≈40 s) persistent current in a toroidal Bose-Einstein condensate held in an all-optical trap. A repulsive optical barrier across one side of the torus creates a tunable weak link in the condensate circuit, which can affect the current around the loop. Superflow stops abruptly at a barrier strength such that the local flow velocity at the barrier exceeds a critical velocity. The measured critical velocity is consistent with dissipation due to the creation of vortex-antivortex pairs. This system is the first realization of an elementary closed-loop atom circuit.     

Intracavity ionization and pulse formation in femtosecond enhancement cavities

We experimentally and numerically investigate the intracavity ionization of a dilute gas target by an ultrashort pulse inside a femtosecond enhancement cavity. Numerical simulations detail how the dynamic ionization of the gas target limits the achievable peak intensity of the evolving intracavity pulse beyond that of linear cavity losses, setting a constraint on the strength of the nonlinear interaction that can be sustained in such optical cavities. Experimental measurements combined with numerical simulations predict ionization levels in a femtosecond enhancement cavity for the first time. We demonstrate how the resonant response of the femtosecond enhancement cavity can itself be used as a sensitive probe of optical nonlinearities at high intensities.     

Ueber die Untersuchung von Gaskohle

Ohne Zusammenfassung     

Synthesis of alkylpyrroles by use of a vinamidinium salt

The synthesis of alkyl-substituted 2-pyrrolecarboxylate esters has been accomplished by the condensation reaction of a symmetrical vinamidinium salt and glycine ester derivatives.