Electrocatalytic performance of different Mo-phases obtained during the preparation of innovative Pt-MoC catalysts for DMFC anode

Electrochemical studies of new binary Pt-MoC electrocatalysts prepared by carbothermal-reduction method have been developed. The XRD and XPS characterization allows to determine the structure of core–shell Mo_carb-particles, with a reduced-Mo core (Mo₂C, MoO₂ and/or Mo⁰) and a MoO₃-shell (2–3 nm). Upon adding Pt, Pt interacts with MoO₃-shell.     

Calculation of tool paths for a torus mill on free-form surfaces on five-axis machines with detection and elimination of interference

Within the framework of a study carried out in cooperation with the Sapex Company, we sought to develop an overall machining program for free-form surfaces on a 5-axis NC machine tool. This program comprises a certain number of general cases that will then have to be adapted to specific situations. In this paper, we present the algorithms allowing the following cases to be dealt with:Positioning a torus mill at a given point on the surface with automatic search for interference between the end of the tool and the surface.Angular correction or the raising of the tool to avoid interference.Calculation of trajectories for a rolling torus mill on a ruled surface resting on a free-form surface of the NURBS (Non Uniform Rational B-Splines) type.The latter can be broken down into two parts:Seeking the axis position on the adjusted surface.Determination of the tool's point of contact on the freeform surface.     

A method to evaluate quality of modelling languages based on the Zachman reference taxonomy

Software Quality Journal - The model-driven engineering (MDE) paradigm promotes the use of conceptual models in information systems (IS) engineering and research. As engineering products,...     

Divinyl sulfone-eleostearate adducts as plasticizers for nitrile rubber

Four divinyl sulfone-eleostearate adducts were synthesized and compared with dibutyl sebacate as plastieizers for nitrile rubber. Three of these, the adducts of methylalpha-eleostearate, its hydrogenated derivative, and that of tung oil, were found to be satisfactory primary plastieizers. The stocks prepared from the unhydrogenated adducts were superior in plasticizing efficiency to those prepared from their hydrogenated derivatives. The divinyl sulfone-tung oil adduct yielded a rubber which met the low-temperature flexibility requirements (−40°C.) of the automotive industry. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Services, U.S. Department of Agriculture.     

Pulmonary atresia with intact i.v. septum (author''s transl)

Eight cases of pulmonary atresia with intact ventricular septum, are reviewed. Three corresponded to the group with small or hypoplastic right ventricle and five to the one with normal or enlarged right ventricular cavity. The electrocardiogram was of less value than plain chest radiography for the differential diagnosis of both groups. Cardiac catheterization revealed a right to left atrial shunt and the suprasystemic level of the right ventricular pressure. Selective angiocardiography demonstrates the stop of contrast at the level of pulmonary valve. Five patients were operated. An ascending aorta to right pulmonary artery anastomosis, Waterston type, was performed in three patients. Pulmonary valvotomy was carried out in the others.     

EVA Nanocomposites Elaborated with Bentonite Organo‐Modified by Wet and Semi‐Wet Methods

EVA copolymer/organoclay nanocomposites were prepared using melt‐compounding. Organoclays were obtained using wet and semi‐wet modification methods. These methods enable us to obtain organoclays with adequate modifier incorporation, but organoclays with a homogeneous and narrow agglomeration size distribution were obtained only with the wet method. TS and EB were higher for nanocomposites obtained with organoclays prepared using the wet method. Analysis of Limiting Oxygen Index, UL94 test and Cone Calorimeter test showed that the retardant properties of nanocomposites were also influenced by the kind of modifiers and the modification method.

     

Alumina/Zirconia Micro/Nanocomposites: A New Material for Biomedical Applications With Superior Sliding Wear Resistance

In the present investigation, the sliding wear behavior is described for Al₂O₃/ZrO₂ micro/nanocomposites and monolithic alumina of similar grain size under defined conditions of a constant sliding speed and different loads (20–150 N). Nano ZrO₂ particles (1.7 vol%) were observed uniformly distributing throughout the composites, and most of them were located within the matrix alumina grains. The wear rate of the alumina and the micro/nanocomposites increased as the contact load increased and a clear transition in friction and wear behavior was observed in both materials. However, the nanocomposite wear resistance at low contact loads was one order of magnitude higher than that of the alumina. In the severe regime, no difference was observed among the materials. The low wear rate (10⁻⁷ mm³·(N·m)⁻¹) along with low pullout indicates higher wear resistance of micro/nanocomposites in the mild regime compared with monolithic alumina. Based on the morphological observation of worn surfaces by scanning electron microscope and on residual stress analysis performed by neutron diffraction, some wear mechanisms of Al₂O₃–ZrO₂ micro/nanocomposites are proposed. The high wear resistance of the nanocomposites is discussed in terms of fracture resistance properties and residual stress. Improvements in mechanical and tribological properties of these composites make them promising candidates for biomedical applications.     

Electrochemical mineralization of sodium dodecylbenzenesulfonate at boron doped diamond anodes

Results are reported of the electrochemical oxidation of sodium dodecylbenzenesulfonate (SDBS), a common surfactant, at boron-doped diamond anodes. The measured critical micelle concentration (CMC) for SDBS in water at 24 °C was almost 150 mg dm⁻³, but this decreased to almost 30 mg dm⁻³ in 0.1 M sodium sulfate. Cyclic voltammetry of a boron doped diamond (BDD) electrode in aqueous SDBS solutions exhibited oxidation current densities at very positive potentials; however, solutions of monomers at concentrations <CMC gave rise to higher current densities than in higher concentration solutions that formed micelles. Galvanostatic electrolyses, with samples analyzed for Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD), were performed in an electrolytic flow cell without separator, operating in batch recycle mode, using solutions containing SDBS at initial concentrations of 25 and 250 ppm. SDBS in basic media (pH = 12) exhibited lower TOC removal rates than in acidic or neutral solutions, due to concurrent oxidation of dissolved carbonates at potentials less positive than required for water oxidation, as evident in cyclic voltammograms. Decreasing the [electrolyte]/[surfactant] ratio from 200 to 10 increased TOC removal rates. For solutions containing monomers, TOC removal rates also increased with flow rate in the second part of the electrolysis, corresponding to reaction of smaller, fragmented organic compounds. When COD removal from a solution containing SDBS micelles was mass transport controlled, current efficiencies were constant at ca. 50%, due to dimerisation of hydroxyl radical to H₂O₂ and its oxidation to dioxygen.