Vertically aligned carbon nanotube‐based composite: Elaboration and monitoring of the nanotubes alignment

We present the different elaboration steps of a composite formed of carbon nanotubes (CNT) carpet embedded in an epoxy polymer. Detailed characterization at each step of the elaboration process is performed. The good alignment of CNT in as‐grown carpets is kept all along the elaboration process of the composite, as it is measured at both macro and microscopic scales by X‐ray scattering. We also ensured by X‐ray fluorescence measurements that the iron‐based catalyst particles used for the synthesis were removed from the carpet after a high temperature post‐annealing treatment. These measurements give valuable information for further applications involving unidirectional nanotube composites and membranes, where CNT alignment is a key parameter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39730.     

Hybrid film of chemically modified graphene and vapor-phase-polymerized PEDOT for electronic nose applications

A hybrid of graphene and conducting polymer holds great potential as the active materials for high performance chemical sensor application. In this work, a thin hybrid film of reduced graphene oxide (RG-O) and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated by means of vapor phase polymerization and explored as active material for chemical sensors. The chemical sensors based on hybrid film of RG-O and PEDOT are capable of detecting electrical signals caused by the absorption of trace levels of different analyte vapors with high sensitivity, selectivity and fast response.     

Learning correct responses and errors in the Hebb repetition effect: Two faces of the same coin.

In a serial recall task, the Hebb repetition effect occurs when recall performance improves for a sequence repeated throughout the experimental session. This phenomenon has been replicated many times. Nevertheless, such cumulative learning seldom leads to perfect recall of the whole sequence, and errors persist. Here the authors report evidence that there is another side to the Hebb repetition effect that involves learning errors produced in a repeated sequence. A learning measure based on past recalls (correct or incorrect) shows that the probability of a given response increases with the number of prior occurrences of that response. The pattern of results reveals another manifestation of the Hebb repetition effect and speaks to the nature of implicit learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cocaine seeking by rats is a goal-directed action.

In 2 experiments rats were trained to self-administer intravenous cocaine on chained schedules using different responses in the initial (drug-seeking) and terminal (drug-taking) links. In both between- (Exp 1) and within-subject designs (Exp 2), the drug-taking response was then either extinguished or reinforced in the absence of the opportunity to perform the seeking response. In a subsequent extinction test with the seeking manipulanda alone, the rate of drug seeking was reduced after the prior extinction of the associated taking response. An additional group trained with a sucrose reinforcer showed a comparable devaluation effect. These findings demonstrate that seeking responses for cocaine and food rewards are mediated by a representation of the contingency between seeking response and the opportunity to take the reward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpretation of experimental data from rapid compression machines without creviced pistons

Over the last two decades, experimental data of the nature of species evolution profiles and ignition delays from rapid compression machines (RCMs) has been used to develop and validate chemical kinetic mechanisms at low-to-intermediate temperatures and elevated pressures. A significant portion of this overall dataset is from RCMs that had not employed a creviced piston to contain the roll-up vortex. The detrimental influence of the roll-up vortex and the thermokinetic interactions due to the resulting temperature non-homogeneity during the negative temperature coefficient (ntc) regime have been documented in the literature. However, the adequacy of the homogeneous modeling of RCMs without creviced pistons during reactive conditions has not been investigated. In this work, computational fluid dynamics simulations of an RCM without a creviced piston are conducted for autoignition of n-heptane over the entire ntc regime over a range compressed pressures from 5 to 18 bar. The results from the CFD simulations highlight the non-homogeneity of autoignition and reveal significant quantitative discrepancy in comparison to homogeneous modeling, particularly for the hot ignition delay in the ntc regime. Specifically, the roll-up vortex induced temperature non-homogeneity leads to diminution of the ntc behavior. The experimental data from RCMs without creviced piston needs to be taken with caution for quantitative validation and refinement of kinetic mechanism, particularly at conditions when ntc behavior is highly pronounced.     

Low salt petroleum produced water reuse: a farming alternative outside the food chain.

Oil and gas production gives rise to water production depending on the state of maturation of the Field. This means large volumes of water available. Today, this water is partly re-injected into the reservoir. Totalfinaelf's sustainable contribution to preserve water resources is to propose an alternative utilization: the reuse of produced waters from petroleum activities, outside the food chain. The aim of the first part of this study is to demonstrate the feasibility of utilizing low-salt water (<20 g/l) cleaned of hydrocarbons, for agricultural or forest irrigation. Rudimentary technologies such as artificial wetlands were tested to remove hydrocarbon substances and preliminary tests were performed with cotton (Gossypium hirsutum) and hemp (Cannabis sativa). Among the species tested in real conditions (greenhouse), hemp was affected by saline water whereas the results obtained for cotton were representative of the average worldwide production. These results validate the reuse of low-salt produced water in climatic conditions with expected temperatures of up to 37 degrees C in summer and 25 degrees C in winter. Following these results, field pilots are planned. Further research is planned to focus, taking into account local needs and environmental and production constraints.     

Manipulation of periodic Coulomb blockade oscillations in ultra-scaled memories by single electron charging of silicon nanocrystal floating gates

Ultra-scaled silicon nanocrystal memories fabricated on a silicon-on-insulator substrate exhibit very periodic Coulomb blockade oscillations at 4.2 K. We control the phase of those oscillations by charging and discharging the floating gate with a single electron. We can distinguish between resonances due to the whole channel area covered by the gate and impurity levels localized in the access regions and less coupled to the gate. Comparison with a reference device without nanocrystals is also reported.     

PERFEX: A cellular performance support expert

PERFEX (PERFormance EXpert) is an intelligent graphical software system that automates performance analysis and tuning of the cellular network. It combines artificial intelligence technologies with advanced graphics to assist performance engineers in analyzing cellular network performance data, validating network configuration, tuning system performance parameters, and carrying out special cellular engineering tasks. PERFEX is installed and in use in 25 GTE markets.