Electron transport through a metal-molecule-metal junction

Molecules of bisthiolterthiophene have been adsorbed on the two facing gold electrodes of a mechanically controllable break junction in order to form metal-molecule(s)-metal junctions. Current-voltage (I-V) characteristics have been recorded at room temperature. Zero bias conductances were measured in the 10-100 nS range and different kinds of non-linear I-V curves with step-like features were reproducibly obtained. Switching between different kinds of I-V curves could be induced by varying the distance between the two metallic electrodes. The experimental results are discussed within the framework of tunneling transport models explicitly taking into account the discrete nature of the electronic spectrum of the molecule.Comment: 12 pages, 12 figures to appear in Phys. Rev. B 59(19) 199

Electron transport through rectifying self-assembled monolayer diodes on silicon: Fermi level pinning at the molecule-metal interface

We report the synthesis and characterization of molecular rectifying diodes on silicon using sequential grafting of self-assembled monolayers of alkyl chains bearing a pi group at their outer end (Si/sigma-pi/metal junctions). We investigate the structure-performance relationships of these molecular devices and we examine to what extent the nature of the pi end-group (change in the energy position of their molecular orbitals) drives the properties of these molecular diodes. For all the pi-groups investigated here, we observe rectification behavior. These results extend our preliminary work using phenyl and thiophene groups (S. Lenfant et al., Nano Letters 3, 741 (2003)).The experimental current-voltage curves are analyzed with a simple analytical model, from which we extract the energy position of the molecular orbital of the pi-group in resonance with the Fermi energy of the electrodes. We report the experimental studies of the band lineup in these silicon/alkyl-pi conjugated molecule/metal junctions. We conclude that Fermi level pinning at the pi-group/metal interface is mainly responsible for the observed absence of dependence of the rectification effect on the nature of the pi-groups, even though they were chosen to have significant variations in their electronic molecular orbitalsComment: To be published in J. Phys. Chem.

Quantitative Analysis of Apache Storm Applications: The NewsAsset Case Study

The development of Information Systems today faces the era of Big Data. Large volumes of information need to be processed in real-time, for example, for Facebook or Twitter analysis. This paper addresses the redesign of NewsAsset, a commercial product that helps journalists by providing services, which analyzes millions of media items from the social network in real-time. Technologies like Apache Storm can help enormously in this context. We have quantitatively analyzed the new design of NewsAsset to assess whether the introduction of Apache Storm can meet the demanding performance requirements of this media product. Our assessment approach, guided by the Unified Modeling Language (UML), takes advantage, for performance analysis, of the software designs already used for development. In addition, we converted UML into a domain-specific modeling language (DSML) for Apache Storm, thus creating a profile for Storm. Later, we transformed said DSML into an appropriate language for performance evaluation, specifically, stochastic Petri nets. The assessment ended with a successful software design that certainly met the scalability requirements of NewsAsset

Interfaces and Interphases in Ca and Mg Batteries

The development of high energy density battery technologies based on divalent metals as the negative electrode is very appealing. Ca and Mg are especially interesting choices due to their combination of low standard reduction potential and natural abundance. One particular problem stalling the technological development of these batteries is the low efficiency of plating/stripping at the negative electrode, which relates to several factors that have not yet been looked at systematically; the nature/concentration of the electrolyte, which determines the mass transport of electro-active species (cation complexes) toward the electrode; the possible presence of passivation layers, which may hinder ionic transport and hence limit electrodeposition; and the mechanisms behind the charge transfer leading to nucleation/growth of the metal. Different electrolytes are investigated for Mg and Ca, with the presence/absence of chlorides in the formulation playing a crucial role in the cation desolvation. From a R&D point-of-view, proper characterization alongside modeling is crucial to understand the phenomena determining the mechanisms of the plating/stripping processes. The state-of-the-art is here presented together with a short perspective on the influence of the cation solvation also on the positive electrode and finally an attempt to define guidelines for future research in the field

Anomaly Detection for Diagnosing Failures in a Centrifugal Compressor Train

Predicting machine failures is of the utmost importance in industrial systems as it can turn expensive crashes and repair costs into affordable maintenance costs. To this end, this paper presents preliminary work for detecting failures in a centrifugal compressor train based on sensorial data. We show the detection capabilities of a two-step process consisting of: (1) a preprocessing step to reduce the dimensionality of the input data using Principal Component Analysis, and (2) an anomaly detection step using the Mahalanobis distance to detect anomalous observations on the sensors' data. The experiments using real-world data demonstrate the feasibility of our approach and the ability of the method to detect the failures eight days in advance

オンガク エンソウ ニオケル ヒョウゲン ツイキュウ プロセス ニツイテ ノ ケンキュウ : エンソウカ エノ インタビュー エンソウ シミュレーション チョウサ カラ

This study involved an investigation of the process for pursuing expressions for playing a musical piece. Two musicians were interviewed about how they pursued expressions of a musical piece ; additionally, they simulated this process for the researcher. Accordingly, the findings of the study are revealed. Pursuing the expression for playing a musical piece occurs in two phases. In the first phase, musicians examine the outline of a musical piece and acquire bodily wisdom and insight for playing it. The goal of this phase is to play the piece fluently without notes, although the aim is not only to develop solutions to technical problems. In this phase, musicians comprehend the structure of the piece and develop tastes and fascinations for it by repeatedly playing the piece. These foundations prepare musicians for the next phase. In the second phase, musicians pursue satisfactory expressions of the piece using various sound images and technical skills. Leads for the pursuit are the results of analyzing the piece, taste preferences and fascinations associated with the piece, the message of the composer, performances of others(CDs)，reflections on their own recorded performances, and observations from repetitions of the music. These elements are intertwined in a complicated manner and synthesized in the minds of the musicians until they are finally satisfied with their expressions. It is not a logical process ; rather, it is based on musicians’ aesthetic senses or feelings. In addition, a satisfactory expression is not a fixed goal. It changes constantly. The process of pursuing an expression for playing a musical piece differs from the process employed in intellectual thinking based on knowledge of the written word. Musical expression reflects bodily wisdom, judgements based on aesthetic senses or feelings, complexity, synthesis, and variability. The findings of this investigation have led to two suggestions for music education in primary and secondary schools. First, the importance of bodily wisdom should be emphasized ; in other words, playing fluently without notes and having sound images and techniques for achieving them are important skills. It is true that acquiring bodily wisdom takes a long time, and music education in schools does not provide enough time for that. However, underrating the importance of such wisdom may make the pursuit of musical expression difficult, as it is the foundation for this pursuit. Second, the complexity, synthesis, and variability of the process of this pursuit should be acknowledged. The process of finding satisfactory expressions cannot be explained by a single causal relationship. Musicians’ satisfactory expressions come from the synthesis of their many experiences, sound images, senses, and feelings. An idea regarding an expression typically flashes into a musician’s mind in the process of the pursuit. Therefore, students should not be instructed to explain their expressions logically, an approach that differs from what is mostly observed in music education in many primary and secondary schools

Fluorinated functionalized EDOT-based conducting films

Three ethylenedioxithiophene (EDOT) derivatives bearing either perfluoro- or ether perfluoro-alkyl chains were synthesized with the objective to prepare films with dry and chemically immobilized lubrication properties. The corresponding fluorinated PEDOT films were deposited on platinum surface by electropolymerization. Cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM) analyses (both quartz resonant frequency and resonant admittance) of the growing steps are described. The electroactive behavior of the films versus their doping level was followed by electrochemical impedance spectroscopy (EIS) through equivalent circuit fitting procedure and compared to their CV responses. Hysteresis in fit parameters corresponding to capacity and film resistance between the forward and the backward scans are observed and discussed. Control of the chemical structures and charge effects on PEDOT chains are followed by an XPS analysis. From these analyses, it appears that the fluorinated side-arm does not alter both the growing and the electrical properties of the films in respect to the pristine PEDOT taken as reference