Catalytic Transfer Dehydrogenation of Geraniol to Geranial Over Palladium and Copper Supported Catalysts

Dehydrogenation of geraniol into geranial in the presence of a hydrogen acceptor (alkene) was studied. Supported palladium catalysts were not suitable for this transformation, but supported copper catalysts showed promising results at 150 °C; selectivity to the expected geranial was strongly dependent on the support and the calcinations/reduction procedure (>50 % in the presence of Mg–La hydrotalcite-supported copper).     

Dopant profiling of focused ion beam milled semiconductors using off-axis electron holography; reducing artifacts,extending detection limits and reducing the effects of gallium implantation

Focused ion beam (FIB) milling is one of the few specimen preparation techniques that can be used to prepare parallel-sided specimens with nm-scale site specificity for examination using off-axis electron holography in the transmission electron microscope (TEM). However, FIB milling results in the implantation of Ga, the formation of amorphous surface layers and the introduction of defects deep into the specimens. Here we show that these effects can be reduced by lowering the operating voltage of the FIB and by annealing the specimens at low temperature. We also show that the electrically inactive thickness is dependent on both the operating voltage and type of ion used during FIB milling.     

In situ evaluation of density, viscosity, and thickness of adsorbed soft layers by combined surface acoustic wave and surface plasmon resonance

We show the theoretical and experimental combination of acoustic and optical methods for the in situ quantitative evaluation of the density, the viscosity, and the thickness of soft layers adsorbed on chemically tailored metal surfaces. For the highest sensitivity and an operation in liquids, a Love mode surface acoustic wave (SAW) sensor with a hydrophobized gold-coated sensing area is the acoustic method, while surface plasmon resonance (SPR) on the same gold surface as the optical method is monitored simultaneously in a single setup for the real-time and label-free measurement of the parameters of adsorbed soft layers, which means for layers with a predominant viscous behavior. A general mathematical modeling in equivalent viscoelastic transmission lines is presented to determine the correlation between experimental SAW signal shifts and the waveguide structure including the presence of the adsorbed layer and the supporting liquid from which it segregates. A methodology is presented to identify from SAW and SPR simulations the parameters representatives of the soft layer. During the absorption of a soft layer, thickness or viscosity changes are observed in the experimental ratio of the SAW signal attenuation to the SAW signal phase and are correlated with the theoretical model. As application example, the simulation method is applied to study the thermal behavior of physisorbed PNIPAAm, a polymer whose conformation is sensitive to temperature, under a cycling variation of temperature between 20 and 40 degrees C. Under the assumption of the bulk density and the bulk refractive index of PNIPAAm, thickness and viscosity of the film are obtained from simulations; the viscosity is correlated to the solvent content of the physisorbed layer.     

Redox enzymes immobilized on electrodes with solution cosubstrates. General procedure for simulation of time-resolved catalytic responses

In view of the existing and potential applications of electrochemical enzymatic catalysis with redox enzymes immobilized on the electrode surface in biosensors, a numerical calculation procedure for simulating their cyclic voltammetric responses is presented. It is applicable to systems involving a redox cosubstrate in solution. The cosubstrates, substrates, products, and inhibitors are assumed to diffuse linearly (planar electrode) between the electrode and the solution. The reactions in which the various forms of the immobilized enzyme participate may be as numerous and intricate as required by the simulation with no other restriction than the computing time. They may, at will, follow or not follow Michaelis-Menten kinetics. Slow charge-transfer cosubstrates are treated in the framework of Butler-Volmer kinetic law.     

Thermal unfolding of proteins probed at the single molecule level using nanopores

The nanopore technique has great potential to discriminate conformations of proteins. It is a very interesting system to mimic and understand the process of translocation of biomacromolecules through a cellular membrane. In particular, the unfolding and folding of proteins before and after going through the nanopore are not well understood. We study the thermal unfolding of a protein, probed by two protein nanopores: aerolysin and α-hemolysin. At room temperature, the native folded protein does not enter into the pore. When we increase the temperature from 25 to 50 °C, the molecules unfold and the event frequency of current blockade increases. A similar sigmoid function fits the normalized event frequency evolution for both nanopores, thus the unfolding curve does not depend on the structure and the net charge of the nanopore. We performed also a circular dichroism bulk experiment. We obtain the same melting temperature (around 45 °C) using the bulk and single molecule techniques.     

Parallel interference cancellation efficiency for noisy signals in O-CDMA system

The aim of this paper is to evaluate the robustness of Parallel Interference Cancellation (Pic) to noise contribution for an optical Code Division Multiple Access system. The theoretical expression of thePic error probability is developed in the case of white additive Gaussian noise. From theoretical analysis, we show that, even with noise contribution, thePic receiver outperforms the Conventional Correlation Receiver (Ccr). Moreover, the results highlight that, for a given performance, thePic receiver relaxes not only the constraint on the code length, but also the Signal to Noise Ratio compared toCcr. Particularly, this is proofed in access network context, i.e. 30 users withBer lt; 10^?9.     

The staircasing effect in neighborhood filters and its solution.

Many classical image denoising methods are based on a local averaging of the color, which increases the signal/noise ratio. One of the most used algorithms is the neighborhood filter by Yaroslavsky or sigma filter by Lee, also called in a variant "SUSAN" by Smith and Brady or "Bilateral filter" by Tomasi and Manduchi. These filters replace the actual value of the color at a point by an average of all values of points which are simultaneously close in space and in color. Unfortunately, these filters show a "staircase effect," that is, the creation in the image of flat regions separated by artifact boundaries. In this paper, we first explain the staircase effect by finding the subjacent partial differntial equation (PDE) of the filter. We show that this ill-posed PDE is a variant of another famous image processing model, the Perona-Malik equation, which suffers the same artifacts. As we prove, a simple variant of the neighborhood filter solves the problem. We find the subjacent stable PDE of this variant. Finally, we apply the same correction to the recently introduced NL-means algorithm which had the same staircase effect, for the same reason.     

Evaluation of characteristic parameters for high performance hall cells

The current work focuses on presenting specific Hall cells with high performance, and their corresponding parameters. The design, integration, measurements and model development for their performance assessment are necessary stages considered in the generation of the Hall cells. Experimental results regarding the Hall cells absolute sensitivity, offset and offset temperature drift are provided for two particular structures exhibiting the best behavior in terms of maximum sensitivity and lowest offset. Three-dimensional physical simulations were performed for the structures and the Hall mobility was extracted. Representation of the inverse of the geometrical correction factor for the Greek-cross Hall cell is also provided.     

Keep it Simple: A Companion for Simple Wikipedia?

In this paper, we inquire about some of the ways in which the community around Simple Wikipedia—an offspring of Wikipedia, the notorious free online encyclopedia—manages the online collaborative production of reliable knowledge. We focus on how it keeps its collection of articles “simple” and easy to read. We find that the labeling of pages as “unsimple” by core members of the community plays a significant but seemingly insufficient role. We suggest that the nature of this mode of decentralized knowledge production and the structure of Wiki-technology might call for the implementation of an editorial companion to the community.