Multiplexed quantification of proteins adsorbed to surface-modified and non-modified microdialysis membranes

A simple and straightforward method for discovery and quantification of proteins adsorbed onto delicate and sensitive membrane surfaces is presented. The adsorbed proteins were enzymatically cleaved while still adsorbed onto the membranes using an on-surface enzymatic digestion (oSED). This was followed by isobaric tagging, nanoliquid chromatography, and tandem mass spectrometry. Protein adsorption on tri-block copolymer Poloxamer 407 surface-modified microdialysis (MD) membranes were compared with protein adsorption on unmodified MD membranes. Ventricular cerebrospinal fluid (vCSF) kept at 37 °C was used as sample matrix. In total, 19 proteins were quantified in two biological replicates. The surface-modified membranes adsorbed 33% less proteins than control membranes and the most abundant proteins were subunits of hemoglobin and clusterin. The adsorption of clusterin on the modified membranes was on average 36% compared to control membranes. The most common protein in vCSF, Albumin, was not identified adsorbed to the surface at all. It was also experimentally verified that oSED, in conjunction with tandem mass spectrometry can be used to quantify femtomole amounts of proteins adsorbed on limited and delicate surfaces, such as MD membranes. The method has great potential and can be used to study much more complex protein adsorption systems than previously reported.     

Characterizing the structure of Co/Cu and NiFe/Cu multilayered magnetic nanowires

Multilayered magnetic Co/Cu and NiFe/Cu nanowires were grown via template-assisted electrodeposition. Structures were described by means of focused ion beam/scanning electron microscopy and energy dispersive X-ray spectroscopy.     

Electron tomography and morphological analysis of the structure of multicomponent amorphous and nanocrystalline alloys

The structure of amorphous and nanocrystalline alloys of the CoP-CoNiP and CoW-CoNiW systems is investigated by means of electron tomography. The systems?? morphometric characteristics are obtained, and the results from two-dimensional imaging and three-dimensional reconstructions are compared.     

Electric field gradients in dilute aluminium alloys

Electric field gradients probed by¹¹¹In, which are produced in dilute PdAl alloys, were studied with the PAC technique. Four different configurations are found which are probably due to metastable aluminium-rich PdAl phases.     

Mechanistic insights into the phosphine-free RuCp*-diamine-catalyzed hydrogenation of aryl ketones: experimental and theoretical evidence for an alcohol-mediated dihydrogen activation

The commercially available chiral diamine quincorine-amine, originally derived from quinine, was found to be a highly active catalyst for ruthenium-catalyzed hydrogenation of ketones. The complex formed between the quincorine-amine, containing both a primary and a quinuclidine amino function, and RuCp*Cl catalyzes the hydrogenation of aromatic and aliphatic ketones in up to 90% ee approximately 24 times faster than previously reported Ru-diamine complexes. The pseudo-enantiomer of the quincorine-amine, i.e., quincoridine-amine, also showed high activity; however, the enantioselectivities obtained with this catalyst were lower. The reason for the lower, but opposite stereoselectivity seen with the quincoridine-amine, as compared to the quincorine-amine, was rationalized by a kinetic and computational study of the mechanism of the reaction. The theoretical calculations also revealed a significantly lower activation barrier for the alcohol-mediated split of dihydrogen, as compared to the nonalcohol-mediated process, a finding of utmost implication also for the diphosphine/diamine-mediated enantioselective hydrogenation of ketones.     

Theoretical error in sub- and super-equivalence method of isotope dilution analysis with VVV variant and its subvariants

Theoretical errors of the VVV variant and its subvariants are outlined and confronted with the earlier study of other variants. Simple complex forming separation reaction is assumed. Optimal conditions of the analysis are discussed.     

Autocatalytic water dissociation on Cu(110) at near ambient conditions

Autocatalytic dissociation of water on the Cu(110) metal surface is demonstrated on the basis of X-ray photoelectron spectroscopy studies carried out in situ under near ambient conditions of water vapor pressure (1 Torr) and temperature (275-520 K). The autocatalytic reaction is explained as the result of the strong hydrogen-bond in the H2O-OH complex of the dissociated final state, which lowers the water dissociation barrier according to the Br?nsted-Evans-Polanyi relations. A simple chemical bonding picture is presented which predicts autocatalytic water dissociation to be a general phenomenon on metal surfaces.     

Acoustically enriching, large-depth aquatic sampler

In marine biology, it is useful to collect water samples when exploring the distribution and diversity of microbial communities in underwater environments. In order to provide, e.g., a miniaturized submersible explorer with the capability of collecting microorganisms, a compact sample enrichment system has been developed. The sampler is 30 mm long, 15 mm wide, and just a few millimetres thick. Integrated in a multilayer steel, polyimide and glass construction is a microfluidic channel with piezoelectric transducers, where microorganism and particle samples are collected and enriched, using acoustic radiation forces for gentle and labelless trapping. High-pressure, latchable valves, using paraffin as the actuation material, at each end of the microfluidic channel keep the collected sample pristine. A funnel structure raised above the surface of the device directs water into the microfluidic channel as the vehicle propels itself or when there is a flow across its hull. The valves proved leak proof to a pressure of 2.1 MPa for 19 hours and momentary pressures of 12.5 MPa, corresponding to an ocean depth of more than 1200 metres. By reactivating the latching mechanism, small leakages through the valves could be remedied, which could thus increase the leak-less operational time. Fluorescent particles, 1.9 μm in diameter, were successfully trapped in the microfluidic channel at flow rates up to 15 μl min(-1), corresponding to an 18.5 cm s(-1) external flow rate of the sampler. In addition, liquid-suspended GFP-marked yeast cells were successfully trapped.