Characterizing the Influence of Water on Charging and Layering at Electrified Ionic‐Liquid/Solid Interfaces

The importance of water on molecular ion structuring and charging mechanism of solid interfaces in room temperature ionic liquid (RTIL) is unclear and has been largely ignored. Water may alter structures, charging characteristics, and hence performance at electrified solid/RTIL interfaces and is utilized in various fields including energy storage, conversion, or catalysis. Here, atomic force microscopy and surface forces apparatus experiments are utilized to directly measure how water alters the interfacial structuring and charging characteristics of [C₂mim][Tf₂N] on mica and electrified gold surfaces. On hydrophilic and ionophobic mica surfaces, water‐saturated [C₂mim][Tf₂N] dissolves surface‐bound cations, which leads to high surface charging and strong layering. In contrast, layering of dry RTIL at weakly charged mica surfaces is weakly structured. At electrified, hydrophobic, and ionophilic gold electrodes, significant water effects are found only at positive applied electrochemical potentials. Here, the influence of water is limited to interactions within the RTIL layers, and is not related to a direct electrosorption of water on the polarized electrode. More generally, the results suggest that effects of water on interfacial structuring of RTIL strongly depend on both (1) surface charging mechanism and (2) interfacial wetting properties. This may greatly impact utilization/design of RTILs and surfaces for interface‐dominated processes.     

Evaluation of the tensile properties of a material through spherical indentation: definition of an average representative strain and a confidence domain

In the present article, a new method for the determination of the hardening law using the load displacement curve, F–h, of a spherical indentation test is developed. This method is based on the study of the error between an experimental indentation curve and a number of finite elements simulation curves. For the smaller values of these errors, the error distribution shape is a valley, which is defined with an analytic equation. Except for the fact that the identified hardening law is a Hollomon type, no assumption was made for the proposed identification method. A new representative strain of the spherical indentation, called “average representative strain,” ε _aR was defined in the proposed article. In the bottom of the valley, all the stress–strain curves that intersect at a point of abscissa ε _aR lead to very similar indentation curves. Thus, the average representative strain indicates the part of the hardening law that is the better identified from spherical indentation test. The results show that a unique material parameter set (yield stress σ _y, strain hardening exponent n) is identified when using a single spherical indentation curve. However, for the experimental cases, the experimental imprecision and the material heterogeneity lead to different indentation curves, which makes the uniqueness of solution impossible. Therefore, the identified solution is not a single curve but a domain that is called “solution domain” in the yield stress–work hardening exponent diagram, and “confidence domain” in the stress–strain diagram. The confidence domain gives clear answers to the question of uniqueness of the solution and on the sensitivity of the indentation test to the identified hardening laws parameters.     

Electro-thermal characterization of a differential temperature sensor in a 65 nm CMOS IC: Applications to gain monitoring in RF amplifiers

This paper reports on the design solutions and the different measurements we have done in order to characterize the thermal coupling and the performance of differential temperature sensors embedded in an integrated circuit implemented in a 65 nm CMOS technology. The on-chip temperature increases have been generated using diode-connected MOS transistors behaving as heat sources. Temperature measurements performed with the embedded sensor are corroborated with an infra-red camera and a laser interferometer used as thermometer. A 2 GHz linear power amplifier (PA) is as well embedded in the same silicon die. In this paper we show that temperature measurements performed with the embedded temperature sensor can be used to monitor the PA DC behavior and RF activity.     

Stochastic modeling for characterisation of biofilm development with discrete detachment events (sloughing).

The monitoring of biofilm development at a small-scale is often observed to be a stochastic process. This raises important issues concerning the reproducibility of biofilm growth monitoring experiments. By realising that there are limits to the latter, a model of biofilm accumulation curves that takes into account the dynamics of seemingly random fluctuations resulting from sloughing events is proposed. The model is derived from a stochastic differential equation (SDE) based on the logistic equation, adding a stochastic term for the sloughing events and measurement noise. Experimental light absorbance data that correlate with biofilm biomass obtained from the development of phototrophic biofilms are analysed to illustrate the use of SDE modeling.     

Preparation and structural characterisation of a Cd(II) complex with unusual geometry

Reaction of Cd(NO₃)₂ · 4H₂O with ethyl-2-pyridinecarboxylate yields [Cd(NO₃)₂(C₅H₄NCOOEt)₂]. Elemental analyses, conductivity measurements, infrared, ¹H and ¹³C{¹H} NMR spectroscopies and single-crystal X-ray diffraction enabled us to characterise this complex. The crystal structure consists of monomeric units in which the cadmium atom is eight-coordinated.     

Classification of magnetic resonance images from rabbit renal perfusion

The feasibility of using chemometric techniques for the automatic detection of whether a rabbit kidney is pathological or not is studied. Sequential images of the kidney are acquired using Dynamic Contrast-Enhanced Magnetic Resonance Imaging with contrast agent injection. A segmentation approach based upon principal component analysis (PCA) is used to separate out the cortex from the rest of the kidney including the medulla, the renal pelvic, and the background. Two classifiers (Soft Independent Method of Class Analogy, SIMCA; Partial Least Squares Discriminant Analysis, PLS-DA) are tested for various types of data pre-treatment including segmentation, feature extraction, centering, autoscaling, standard normal variate transformation, Savitsky-Golay smoothing, and normalization. It is shown that (i) the renal cortex contains more discriminating information on kidney perfusion changes than the whole kidney, and (ii) the PLS-DA classifiers outperform the SIMCA classifiers. PLS-DA, preceded by an automated PCA-based segmentation of kidney anatomical regions, correctly classified all kidneys and constitutes a classification tool of the renal function that can be useful for the clinical diagnosis of renovascular diseases.     

On-line maximum-order induced hereditary subgraph problems

We first study the competitive ratio for the on‐line version of the problem of finding a maximum‐order induced subgraph satisfying some hereditary property, under the hypothesis that the input graph is revealed by clusters. Next, we focus ourselves on two of the most known instantiations of this problem: the maximum independent set and the maximum clique. Finally, we study a variant of the on‐line maximum‐weight induced hereditary subgraph problem. Our results can also be seen as general reductions, either from off‐line problems to the corresponding on‐line versions, or between on‐line problems. The concept of reduction was absent, until now, from the on‐line computation.     

Environmental impacts of the infrastructure for district heating in urban neighbourhoods

District heating is a technology for distributing centrally produced heat for space heating and sanitary hot-water generation for residential and commercial uses. The objectives are to identify which subsystems and components of a district heating grid are the main contributors to the overall impact of the infrastructure; and provide environmentally oriented design strategies for the future eco-redesign of these kinds of infrastructures. This paper performs a life-cycle assessment (LCA) to determine the environmental impacts of a district heating infrastructure in an urban neighbourhood context. The analysis covers seven subsystems (power plant, main grid, auxiliary components of the main grid, trench works, service pipes, buildings and dwellings) and twelve standard components. The results for the subsystems show that the sources of impact are not particularly located in the main grid (less than 7.1% contribution in all impact categories), which is the focus of attention in the literature, but in the power plants and dwelling components. These two subsystems together contribute from 40% to 92% to the overall impact depending on the impact categories. Concerning the components, only a reduced number are responsible for the majority of the environmental impact. This facilitates identifying effective strategies for the redesign of the infrastructure.     

The greatest allowed relative error in weights and threshold of strict separating systems.

An important consideration when applying neural networks is the sensitivity to weights and threshold in strict separating systems representing a linearly separable function. Perturbations may affect weights and threshold so that it is important to estimate the maximal percentage error in weights and threshold, which may be allowed without altering the linearly separable function. In this paper, we provide the greatest allowed bound which can be associated to every strict separating system representing a linearly separable function. The proposed bound improves the tolerance that Hu obtained. Furthermore, it is the greatest bound for any strict separating system. This is the reason why we call it the greatest tolerance.     

A drain current model for Schottky-barrier CNT-FETs

We present here a physics-based drain current model for Schottky-barrier carbon nanotube field-effect transistors. The model captures a number of features exhibited by these transistors such as thermionic and tunnel emission, ambipolar conduction, ballistic transport, multimode propagation and electrostatics dominated by the nanotube capacitance