Resistance welding of aluminium and aluminium alloys

Special features of the process of resistance welding of aluminium and its alloys and also equipment manufactured by the CEA and supplied by Weber Comechanics are described.     

Electrocatalytic properties of carbon nanotube carpets grown on Si-wafers

Electrocatalytical activity of carbon nanotube carpets grown on oxidized silicon wafers by spray pyrolysis catalytic chemical vapor deposition has been examined for use in electrochemical devices. To determine the influence of electron donor doping on electrochemical quality, N-atoms were incorporated into the nanotube structure during growth. N-doping, as revealed by electron microscopy, Raman spectroscopy and X-ray diffraction data, led to essential changes of the tubule morphology and structure. For the electrochemical investigation of the carbon nanotube electrodes produced, cyclic voltammetry and electrochemical impedance spectroscopy were used, while ferrocene (FeCp₂) and uric acid served as reference redox systems. Results have revealed enhanced electron transfer kinetics on the N-doped electrodes. The electronic band structure of carbon nanotubes and electrochemical gating are shown to be responsible for the charge transfer kinetics on nanotube electrodes.     

Chronic pain and depression: role of perceived impact and perceived control in different age cohorts

Chronic pain adversely affects individuals' physical as well as emotional well-being. A cognitive-behavioral model has been proposed to explain the role of cognitive appraisal variables in mediating the development of emotional distress following pain of long duration. There is little evidence linking the prevalence of depression in chronic pain patients to life stage, but there are suggestions in the literature that the link between medical illness and depression may be stronger in elderly patients. One purpose of this study was to replicate the efficacy of a previous study of the cognitive-behavioral mediation model in explaining the association between pain and depressed affect. A second purpose of this study was to extend the cognitive-behavioral model to evaluate relationships among pain, cognitive appraisal variables, and depressive affect in the elderly chronic pain population. One hundred chronic pain patients were divided into two age groups (< or = 69 years and > or = 70 years). A path analysis conducted for the total sample supported the cognitive-behavioral mediation model of depression in chronic pain, in which cognitive appraisal variables mediate the pain-depression relationship. Correlations among variables in each of the two age groups, however, revealed different patterns of association. Consistent with the cognitive-behavioral model, the younger patients demonstrated a low and non-significant correlation between pain severity and depression (r = 0.01). Conversely, a strong direct association was observed in the older patients between these variables (r = 0.51). These results suggest that the relationship between pain and depression varies substantially depending upon age cohort.     

Life time prediction of old bridges

The prediction of a realistic lifetime and the prolongation of the service life of a structure is an important task to reduce costs of civil engineering structures. The usual theoretical predictions are not very reliable. The prediction model used consists of a load model, a system‐transfer model and a damage model. The results of these sequentially coupled models are usually unreliable, especially the influence of the uncertain load and damage models controls the reliability of the result. A method based on monitoring strategies is presented, which avoids these problems. Expected trends of future traffic are considered. If the remaining life time of existing structures should be assessed, information about the strain time history of the past is needed. It is shown how these data can be generated taking into account the estimated statistics of the load in the past, the dynamic behaviour and the bumpiness of the road. Synthetic time series of the local strains are generated which include the real statistics of the process and cluster effects induced by truck convoys.     

Extending the simultaneous-sequential paradigm to measure perceptual capacity for features and words.

In perception, divided attention refers to conditions in which multiple stimuli are relevant to an observer. To measure the effect of divided attention in terms of perceptual capacity, we introduce an extension of the simultaneous-sequential paradigm. The extension makes predictions for fixed-capacity models as well as for unlimited-capacity models. We apply this paradigm to two example tasks, contrast discrimination and word categorization, and find dramatically different effects of divided attention. Contrast discrimination has unlimited capacity, consistent with independent, parallel processing. Word categorization has a nearly fixed capacity, consistent with either serial processing or fixed-capacity, parallel processing. We argue that these measures of perceptual capacity rely on relatively few assumptions compared to most alternative measures. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Electronic Structure of C60, CuPc, and C60/CuPc Nanoparticles and their Layers

The idea to form C₆₀/CuPc dispersed nanoheterojunctions by photoexcitation of a mixture of C₆₀ and CuPc nanoparticles has been realized. The electronic structure of the nanoparticles and dispersed nanoheterojunctions formed in the mixture has been characterized by UV-Vis spectroscopy and the comparing with known experimental ultraviolet photoelectron spectra and theoretical models of electronic structure of these molecules. For the mixture of C₆₀ and CuPc nanoparticles in toluene and their coating layer on the quartz substrate the band offsets of the edges of CuPc VB and lowest unoccupied molecular orbital (LUMO) of C₆₀ band are ΔE=1.55 eV and 1.4 eV, respectively. These results show clearly the presence of C₆₀/CuPc dispersed nanoheterojunctions in the solution and on the quartz surface.     

Qualitative and quantitative analysis of petitgrain Eureka lemon essential oil by fused silica capillary column gas chromatography mass spectrometry

The identification of Algerian petitgrain Eureka lemon essential oil was carried out by gas liquid chromatography-mass spectrometry in electronic impact mode using a fused silica capillary column (FFAP). The results enabled a previous study on this oil to be completed where the relative retention data and chemical derivation reactions had been performed. A preparative gas chromatography was applied to give a better g.c.-m.s.analysis of minor compounds; thus, two new products (citronellyl n-propionate and cedrol) were revealed by this method. Only 80 compounds were identified after indexation of 137 mass spectra and after comparison with those in the literature because most mass spectra data banks are not well adapted for the identification of essential oils. A global comparison of the percentage composition of the major compounds of this oil with those in other petitgrain lemon essential oils has revealed distinct differences. From the mass spectra of nine monoterpenic hydrocarbons, it was shown that comparison of the intensity ratio of the characteristic fragment ions in EI mode, which has been suggested by some authors as a general method of identification of compounds with similar mass spectra, is not reliable.     

Interaction of N-fluorescein-5-isothiocyanate pyrrolidine-C60 with a bimolecular lipid model membrane

In this letter we report the first synthesis of a fluorescein-functionalized fullerene, N-fluorescein-5-isothiocyanate pyrrolidine-C₆₀, and its influence on the electrical properties of a bimolecular lipid model membrane.