Enzymatic Reaction in Droplets Manipulated with Liquid Dielectrophoresis

Droplet generation and transportation for biological reactions are conducted with liquid dielectrophoresis (LDEP), forming two hundred picoliter droplets and aligning them in an open environment above the micro‐machined electrodes. The generation of the dielectrophoresis signals was critically examined to actuate droplets in biological solutions without excessive Joule heating. Enzymatic reactions between β‐galactosidase and fluorescein di‐β‐D ‐galactopyranoside were succeeded in manipulated droplets, which was confirmed by fluorescence imaging. These results allow us to propose the integration of LDEP actuation in high throughput biomolecular assays.     

Experimental test of universality of the Anderson transition

We experimentally test the universality of the Anderson three dimensional metal-insulator transition, using a quasiperiodic atomic kicked rotor. Nine sets of parameters controlling the microscopic details have been tested. Our observation indicates that the transition is of second order, with a critical exponent independent of the microscopic details; the average value 1.63±0.05 agrees very well with the numerically predicted value ν=1.58.     

Signed words and permutations, V; a sextuple distribution

We calculate the distribution of the sextuple statistic over the hyperoctahedral group B _n that involves the flag-excedance and flag-descent numbers “fexc” and “fdes,” the flag-major index “fmaj,” the positive and negative fixed point numbers “ ” and “ ” and the negative letter number “neg.” Several specializations are considered. In particular, the joint distribution for the pair is explicitly derived.      

Plastic matters: an analytical procedure to evaluate the degradability of contemporary works of art

The most significant results concerning a chemical study to evaluate the degradability of polymeric components in four contemporary works of art, partially or completely realized in plastics, are presented and discussed in this paper. The procedure applied is mainly based on the use of Fourier transform IR and UV–vis spectroscopies and pyrolysis–gas chromatography/mass spectrometry, and consists of the following steps: (1) compositional analysis of the artworks, with particular attention to components which may have a negative effect on the overall ageing; (2) evaluation of the actual state of conservation; (3) investigation of the accelerated ageing of reference polymer samples; and (4) monitoring of the natural ageing of the artworks. On such a basis, the following could be concluded. Stage Evidence by Loris Cecchini is made of poly(ether urethane) elastomer which contains a high amount of phthalates. Their exudation gives a sticky appearance to the artwork and their removal during ageing is the main cause of the loss of flexibility. The latex used by Andrés Pinal for tailoring Traxe de Home is a natural polyisoprene, whose oxidative degradation accounts for the extensive deterioration and yellowing of the artwork. The plaster sculptures of 3D Bodyscans 1:9 by Karin Sander are coated with an aliphatic epoxy resin. Its oxidation with formation of amides is the cause of the surface yellowing. The adhesive used by Dario Villalba for Tierra, Ladrillo y Agua is a commercial poly(vinyl acetate). Simulated photoageing suggests a fast deterioration due to deacetylation and cross-linking, which possibly is the main reason for the actual detachment of debris from the support.     

A Novel Pyrene‐Based Fluorescing Amphiphile with Unusual Bulk and Interfacial Properties

We have synthesised a new, pyrene‐based, low‐molecular‐mass, amphiphilic molecule that displays a wealth of properties of potential interest for aggregation and interfacial applications. In order to elucidate some of the key properties of this molecule, which consists of a pyrene‐containing hydrophobic head and a short PEG‐based hydrophilic tail, we investigate herein some aspects of its concentration‐dependent behaviour in aqueous solutions. We show that the inclusion of the hydrophobic pyrene group not only provides the molecule with intriguing bulk and interfacial properties down to low concentrations, but also with various means of assessing its aggregation behaviour by means of its well‐characterised fluorescence properties. Combining a range of fluorescence techniques with microscopic imaging (optical and Cryo‐TEM), interfacial tension measurements and foaming studies, we have been able to identify and characterise three concentration‐dependant regimes. At low concentrations, the molecule is dissolved in monomeric form. At intermediate concentrations, labile aggregates are formed, which, at higher concentrations, give way to aggregates containing pre‐associated pyrenes. Our measurements strongly imply that the latter aggregates are hexagonally close‐packed tubular micelles. In this latter regime we also find a range of micron‐sized precipitates. Additionally, the molecule displays strong interfacial activity, yet a surprisingly slow dynamics of interfacial adsorption. Finally, we demonstrate the possibility of using it to visualize interfaces and also create reasonably stable (1 hour) and fluorescing foams.     

Chemical functionalization of electrodes for detection of gaseous nerve agents with carbon nanotube field-effect transistors

An innovative sensor for the detection of nerve agents in the gas phase based on a carbon nanotube field-effect transistor was developed. A high sensitivity to organophosphorus gases was obtained by modifying gold electrodes with specific tailor-made self-assembled monolayers.     

High efficiency of cavity-based triaryl-phosphines in nickel-catalysed Kumada-Tamao-Corriu cross-coupling

Combining diaryl-calixarenyl phosphines with [Ni(cod)(2)] resulted in highly active Kumada-Tamao-Corriu cross-coupling catalysts. With one of the ligands, TOFs up to 439,000 mol(ArBr) mol(Ni)(-1) h(-1) were observed in the reaction of 1-bromonaphthalene with PhMgBr. The systems were also found to be active at room temperature with aryl chlorides.     

Iron(III) chloride-tandem catalysis for a one-pot regioselective protection of glycopyranosides

Tandem catalysis by using iron(III) chloride hexahydrate leads to carbohydrate building blocks displaying an orthogonal protecting group pattern as illustrated by the regioselective protection of trehalose and maltose disaccharides.     

Turbulence Modelling of Unsteady Turbulent Flows Using the Stress Strain Lag Model

This paper reports the application of a recently developed turbulence modelling scheme known as the C _as model. This model was specifically developed to capture the effects of stress-strain misalignment observed in turbulent flows with mean unsteadiness. Earlier work has reported the approach applied within a linear k-ε modelling framework, and some initial testing of it within the k-ω SST model of Menter (AIAA J 32:1598–1605, 1994). The resulting k-ε-C _as and SST-C _as models have been shown to result in some of the advantages of a full Reynolds Stress transport Model (RSM), whilst retaining the computational efficiency and stability benefits of a eddy viscosity model (EVM). Here, the development of the the high-Reynolds-number version of the C _as model is outlined, with some example applications to steady and unsteady homogeneous shear flows. The SST-C _as form of the model is then applied to further, more challenging cases of 2-D flow around a NACA0012 aerofoil beyond stall and the 3-D flow around a circular cylinder in a square duct, both being flows which exhibit large, unsteady, separated flow regions. The predictions returned by a range of other common turbulence modelling schemes are included for comparison and the SST-C _as scheme is shown to return generally good results, comparable in some respects to those obtainable from far more complex schemes, for only moderate computing resource requirements.     

Numerical Simulation of Coherent Structures over Plant Canopy

This paper reports large eddy simulations of the interaction between an atmospheric boundary layer and a canopy (representing a forest cover). The problem is studied for a homogeneous configuration representing the situation encountered above a continuous forest cover, as well as for a heterogeneous configuration representing the situation similar to an edge or a clearing in a forest. The numerical results reproduces correctly all the main characteristics of this flow as reported in the literature: the formation of a first generation of coherent structures aligned transversally with the wind flow direction, the reorganization and the deformation of these vortex tubes into horse-shoe structures. The results obtained when introducing a discontinuity in the canopy (reproducing a clearing or a fuel break in a forest), are compared with the experimental data collected in a wind tunnel; here, the results confirm the existence of a strong turbulence activity inside the canopy at a distance equal to 8 times the height of the canopy, referenced in the literature as the Enhance Gust Zone (EGZ) characterized by a local peak of the skewness factor.