Friction and Wear of Self‐Lubricating Polyimides in Vacuum and Air to High Temperatures

In an increasing number of tribosystems, liquid lubrication cannot be applied or its application has to be avoided for environmental reasons. Examples include both plain bearings and linear guides used in space applications and in industrial vacuum production devices, e.g., for flat screens. Demand has also grown to raise the upper working temperatures of tribosystems and vacuum tribometers to around 300°C. For these reasons, a new formulation of polyimide (P84‐HT) for higher temperatures has been developed. Composites (Sintimid) with selected fillers (MoS₂, graphite, polytetrafluoroethylene, carbon fibres) were previously tested as to their general properties (physical, thermal, mechanical, vacuum stability) in temperatures up to 300°C and as regards the ECSS requirements for materials for operation in space (vacuum). The Sintimid compounds were successfully qualified according to these considerations. This paper reports a study of their mechanical properties and friction and wear behaviour. In particular. the influence of environmental parameters ‐ atmosphere and temperature ‐ and load are discussed and compared to other known materials, e.g., Vespel SP3. The tribological results are discussed in terms of the different filler types and their combinations.     

The renin-angiotensin-aldosterone system in mother and fetus at term

Plasma renin activity, renin substrate, angiotensin II, aldosterone and cortisol were measured concurrently and renin concentration calculated in plasma from mothers during labor and delivery, from cord and from newborn infants. The renin-angiotensin-aldosterone system was found strongly stimulated in both mother and fetus. The high values of plasma renin activity in fetus were due exclusively to the high renin concentrations the substrate concentration being normal. In the mother, however, the markedly elevated renin substrate resulted in a doubling of relative values of renin activity compared to renin concentration. Therefore gradients of renin and renin substrate across the placenta are established, but the resulting renin activity is similar on both sides and the levels of generated angiotensin II are also nearly indentical with a good correlation between these last parameters. Aldosterone is as elevated in mother as in fetus whereas cortisol, due to its binding to transcortin, is twice as high in mother as in fetus. No correlation was found between renin activity or concentration of angiotensin II and aldosterone or cortisol indicating that other factors controlling aldosterone are involved.     

Determination of 105 antibiotic,anti-inflammatory,antiparasitic agents and tranquilizers by LC-MS/MS based on an acidic QuEChERS-like extraction

A procedure for screening 105 veterinary drugs in foods by liquid chromatography tandem mass-spectrometry (LC-MS/MS) is presented. Its scope encompasses raw materials of animal origin (milk, meat, fish, egg and fat) but also related processed ingredients and finished products commonly used and manufactured by food business operators. Due to the complexity of the matrices considered and to efficiently deal with losses during extraction and matrix effects during MS source ionisation, each sample was analysed twice, that is ‘unspiked’ and ‘spiked at the screening target concentration’ using a QuEChERS-like extraction. The entire procedure was validated according to the European Community Reference Laboratories Residues Guidelines. False-negative and false-positive rates were below 5% for all veterinary drugs whatever the food matrix. Effectiveness of the procedure was further demonstrated through participation to five proficiency tests and its ruggedness demonstrated in quality control operations by a second laboratory.     

Nanoporous networks derived from functional semi-Interpenetrating Polymer Networks: Preparation and use as ion-exchange chromatographic supports

The utilization of poly(ε-caprolactone) (PCL)/poly(methyl methacrylate-co-methacrylic acid)-based semi-Interpenetrating Polymer Networks as nanostructured precursors provides a straightforward and effective route for engineering COOH-functionalized nanoporous networks. Such functional frameworks can be used as cation-exchange supports in Ion-Exchange Chromatography for the separation of proteins, provided the structures contain a significant initial content of carboxylic acid functions. This investigation illustrates the major role played by the presence of the interconnected pores generated by the oligoester template in the protein retention. The resolution turns out to be better than that obtained with a classically prepared porous support using an organic solvent as a porogen.     

Adhesive bonding of aerospace materials — surface characterization of metallic adherends

Adhesively bonded structures are widely used in the aerospace industry. Unfortunately, adhesion is a macroscopic property depending specifically upon numerous sub-microoscopic parameters so that producing a strong and durable bond is a difficult task which needs many fundamental and applied research investigations. In this context, the surface composition of adherends plays an extremely important role in the overall performance of a bonded structure: it is well known that surfaces of ‘as-received’ materials are chemically very different from the bulk composition and are usually unsuitable for adhesive bonding. Consequently, surfaces of such materials hav to be submitted to appropriate chemical or electrochemical prebonding treatments in order to modify both their morphology and chemistry.

This paper discusses the surface characterization of aluminium, titanium and their alloys at various prebonding stages. Practical applications of X-ray fluorescence spectroscopy, low-energy electron-induced X-ray spectroscopy and glow discharge optical spectroscopy are described.     

Intercalated carbon nanotubes as a template for the preparation of supported heteroatomic nanoparticles

Chemistry in confined conditions is explored at the level of the interlayer space of multiwall carbon nanotubes. Starting from preliminary intercalated tubes, a ligand exchange reaction has been successfully conducted within the former Van der Waals gap, resulting in a final dispersion of heteroatomic particles, around 2 nm large and nearly homogeneous in size, on the outer surface of the tubes. Intercalated tubular carbon architectures thus prove to be interesting templates for a bottom-up preparation of chemically complex supported nanoparticles, with potential activities for versatile applications.     

Molecular lipophilicity potential (MLP) in drug design. Complementing theoretical tools with experimental results

The Molecular Lipophilicity Potential (MLP) is a versatile tool in drug design whose present state and potential developments are reviewed here. The MLP offers a three-dimensional representation of lipophilicity as calculated from partition coefficients. The intermolecular recognition forces and intramolecular effects encoded in lipophilicity are presented, followed by the theoretical foundations and validation of the MLP. It is then demonstrated that the MLP allows for the first time to investigate the dependence of lipophilicity on conformation. As a matter of fact, the MLP combined with an exploration of the conformational space of a solute reveals its "chameleonic" behaviour, i.e. its capacity to adapt to the molecular environment. Other applications of the MLP are presented and illustrated, namely its integration into 3D-QSAR (Comparative Molecular Field Analysis, CoMFA) and its interest as a docking tool.     

Functional interaction of the gp80 and gp130 IL-6 receptors in human B cell malignancies

This study investigated the psychological impact of HIV infection through assessment of posttraumatic stress disorder in response to HIV infection. Sixty-one HIV-positive homosexual/bisexual men were assessed for posttraumatic stress disorder in response to HIV infection (PTSD-HIV) using a modified PTSD module of the DIS-III-R. Thirty percent met criteria for a syndrome of posttraumatic stress disorder in response to HIV diagnosis (PTSD-HIV). In over one-third of the PTSD cases, the disorder had an onset greater than 6 months after initial HIV infection diagnosis. PTSD-HIV was associated with other psychiatric diagnoses, particularly the development of first episodes of major depression after HIV infection diagnosis. PTSD-HIV was significantly associated with a pre-HIV history of PTSD from other causes, and other pre-HIV psychiatric disorders and neuroticism scores, indicating a similarity with findings in studies of PTSD from other causes. The findings from this preliminary study suggest that a PTSD response to HIV diagnosis has clinical validity and requires further investigation in this population and other medically ill groups. The results support the inclusion of the diagnosis of life-threatening illness as a traumatic incident that may lead to a posttraumatic stress disorder, which is consistent with the DSM-IV criteria.