Nickel and nickel-phosphorous matrix composite electrocoatings

Nickel and nickel-phosphorous matrix composite coatings reinforced by TiO₂, SiC and WC particles were produced under direct and pulse current conditions from an additive-free Watts' type bath. The influence of the variable electrolysis parameters (type of current, frequency of current pulses and current density) and the reinforcing particles properties (type, size and concentration in the bath) on the surface morphology and the structure of the deposits was examined. It is demonstrated that the embedding of ceramic particles modifies in various ways the nickel electrocrystallisation process. On the other hand, Ni-P amorphous matrix is not affected by the occlusion of the particles. Overall, the imposition of pulse current conditions leads to composite coatings with increased embedded percentage and more homogenous distribution of particles in the matrix than coatings produced under direct current regime.     

Transient liquid phase bonding of steel using an Fe–B interlayer

Transient liquid phase bonding processes have been performed to join two carbon steel tubes using Fe_96.2B_3.8 wt% amorphous ribbons as interlayers. Welding experiments were performed at the temperature T ≈ 1,250 °C for different durations and under pressures of 2, 3 and 4 MPa. From metallographic inspection it is concluded that the bonding process ends in 7.0 min if a pressure of 4 MPa is applied whereas the process results incomplete if less pressure is applied. A 1D model using a finite element method has been developed for the simulation of a transient liquid phase bonding process. This model was applied to the bonding of steel/Fe–B glassy metals/steel. The computed results allow us to understand the role played by the variables involved in the bonding process.     

The synthesis, physicochemical properties and anodic polymerization of a novel ladder pentaphenylene

The synthesis, crystal structure, electrochemical and optical properties of a novel blue emitting ladder pentaphenylene are reported and compared with those of its 3π−2 spiro parent, in order to study the effect of the spiro-linked fluorene rings. Anodic oxidation of the novel compound results via electropolymerization, in the formation of an electroactive material that displays interesting electrochemical and optical properties.     

Pancreaticoduodenal artery aneurysm--a life-threatening cause of gastrointestinal hemorrhage: case report and review of the literature

Gastrointestinal bleeding caused by erosion of a pancreaticoduodenal artery aneurysm in patients with pancreatitis is a rare but potentially life threatening disease. In this case report, the successful treatment of a patient bleeding from a ruptured pancreaticoduodenal artery aneurysm is described. A review of the literature of reported cases discusses the value of early angiographic intervention in patients with unexplained gastrointestinal hemorrhage and suspected rupture of an aneurysm.     

Verification of Real-Time Systems using Linear Relation Analysis

Linear Relation Analysis [11] is an abstract interpretation devoted to the automatic discovery of invariant linear inequalities among numerical variables of a program. In this paper, we apply such an analysis to the verification of quantitative time properties of two kinds of systems: synchronous programs and linear hybrid systems.     

l’analyse du fonctionnement interactif à l’évaluation du marché des téléconférences

The authors are concerned with the comparative analysis of interactive processes in a meeting, subject to various situations of mediation. The research is based on the analysis of records of actual meetings, either in face to face situations, or in audio or video-conferences. Interactivity is first defined as the ability to interrupt in order to help the communication process. The mechanisms which regulate this interactivity are then analyzed, as well as its functions in the way exchanges proceed and speech is built. The thesis is put forward that parallel to the exchange of informations linked to the contents of the meeting, an exchange of control signals, chiefly of an infra and non verbal kind, takes place as on a signalling channel, the role of which is to regulate: the allocation of speech turn-taking, the mutual understanding of participants, the setting out of the speech issued on the main channel, the construction of the common knowledge useful to the achievement of the task, the regulation of speech status, the production of ambiguous and unopposable speeches… The study enables identification of the disturbances brought to the regulation of interactivity when the technical conditions of mediation do change, and allows improvement of the designing of the protocoles aimed at selecting voice and image data before their transmission through teleconferencing systems.     

Localization of Myf-5, MRF4 and alpha cardiac actin mRNAs in regenerating Xenopus skeletal muscle

Dendrotoxin I (DTX-I) is a 60-residue peptide from the venom of the black mamba snake Dendroaspis polylepis, which binds to neuronal K+ channels. The structure reported previously for DTX-I was synthesized for the first time by a solution procedure. The synthetic product was confirmed to have the correct primary and disulfide structure determined by peptide mapping, sequence analysis and mass measurements. Comparison of synthetic DTX-I with the natural one by high-performance liquid chromatography and capillary zone electrophoresis, as well as by sequence analysis, revealed that the Asn residue at position 12 in the synthetic peptide was Asp in the natural product. Synthesis of DTX-I with Asp at position 12 gave a peptide identical with the natural product in all aspects. NMR analysis of synthetic [Asn12]- and [Asp12]-DTX-I also supported our findings that the Asn residue at position 12 in the DTX-I molecule should be revised as Asp. [Asn12]- and [Asp12]-DTX-I had very similar binding affinities when tested against radiolabeled dendrotoxin binding to rat brain synaptosomal membranes.     

Useful direct conversion of tetrahydropyranyl ethers of fatty alcohols into fatty acids

Tetrahydro-2-pyranyl ethers from fatty primary alcohols can be converted in a one-step procedure into the corresponding carboxylic acids in high yields. This process avoids the synthesis of symmetrical esters, particularly for long-chain compounds. This reaction proved to be useful, for instance, to produce polyunsaturated fatty acids immediately before their biological testing.     

Tomographisches Messen der relativen Phasenanteile in zweiphasigen Strömungen fluider Phasen

A new tomographic process measures the spatial phase fractions in slug flow and possesses high positional and temporal resolution. The measuring method is based on the electrical conductivity of the flowing fluids, which is measured between numerous parallel wires. The individual measurements are directly proportional to the relative liquid content. With the aid of an iterative reconstruction procedure they permit calculation of the phase fractions. The quality of reconstruction is improved by consideration of a priori knowledge. The temporal resolution is 0.009 s and the spatial resolution less than 0.1% of the flow cross-section.