Rhodium‐Catalyzed Hydrogenation of Alkenes by Rhodium/Tris(fluoroalkoxy)phosphane Complexes in Fluorous Biphasic System

The reaction of [Ir(μ‐Cl)(COD)]₂ with various fluorous derivatives of triphenylphosphane containing a para‐, meta‐, or ortho‐(1H,1H‐perfluoroalkoxy)‐substituted fluorous phosphane P(C₆H₄‐ORf)₃ (Rf=CH₂C₇F₁₅, CH₂CH₂CH₂C₈F₁₇) and CO (1 atm) gives the corresponding trans‐[Ir(μ‐Cl)(CO){P(C₆H₄ORf)₃}₂]. The IR ν_CO values of these complexes give some information on the donor/acceptor properties of the phosphanes. These fluorous derivatives of triphenylphosphane, as well as a phosphane bearing two (1H,1H‐perfluoroalkyloxy) chains at the 3,5‐positions, were used in association with [Rh(μ‐Cl)(COD)]₂ or [Rh(COD)₂]PF₆ in the reduction of methyl cinnamate, 2‐cyclohexen‐1‐one, cinnamaldehyde, and methyl α‐acetamidocinnamate in a two‐phase system D‐100/ethanol under 1 bar hydrogen at room temperature. Some differences in catalytic activity were observed in the reduction of methyl cinnamate, the most active catalyst being the rhodium complex containing the phosphane with the p‐fluorous ponytail. Recycling of the fluorous catalyst was possible, particularly using the p‐substituted phosphane, where no significant loss of catalyst or activity was observed, and generally with very low leaching of rhodium or phosphane in the organic phase.     

Polymer-grafted-nanoparticle surfactants

We have studied the surface behavior of nanoparticles, which are lightly grafted with polymer chains, when they are mixed with matrix chains of the same architecture as the grafts. We consider the particular case where the nanoparticle core and the grafted polymer chains energetically dislike each other and show that the extent of surface segregation of these "hairy" nanoparticles and their self-assembly into a variety of structures can be tuned by varying the number and the length of the grafted chains and the matrix chain length. These results unequivocally show that grafted nanoparticles in polymer matrices behave akin to block copolymers (or amphiphiles) in selective solvents, with readily controllable surface behavior.     

Ester and epoxide functionalization of high‐density polyethylene by thermolysis method—An FTIR study

High‐density polyethylene was functionalized using a thermolysis method in the presence of functionalized peroxides at different temperatures and at various peroxide concentrations. It was found that both percentage cross‐linking (% CL) and percentage functionalization (% Fn) increased with an increase in peroxide concentration. The ester and epoxide functionalization was confirmed by FTIR spectroscopy. Ester functionalization was further confirmed by saponification and acidolysis reaction. The functionalization capacities of acrylic ester peroxide and acrylic acid peroxide were determined and compared. A plausible reaction mechanism has been proposed to explain the experimental results obtained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 761–765, 2005     

An 8-Gb/s capacitively coupled receiver with high common-mode rejection for uncoded data

An 8-Gb/s receiver is demonstrated in 0.35-/spl mu/m SiGe with two on-chip 60-fF ac-coupling capacitors. These capacitors are formed by on-chip metal layers and have a breakdown voltage of at least /spl plusmn/690 V, which is the dc input range of the receiver. The receiver especially resists strong ac common-mode edges with a slew rate up to 4V/ns for enhanced EMI rejection. The self-clocked quantized feedback technique used, features uncoded data that contains long sequences of consecutive identical digits or ac-unbalanced data. The differential input sensitivity is 0.5-1.1Vpp with a supply voltage between 2.5 and 3.5 V.     

Hybrid soliton nuclear reactors: A model and simulation (encapsulated long living accelerator driven system)

We intend to explore the potential of Hybrid Soliton Reactors (Réacteur Hybride à Soliton, RHYS) for producing energy. In our case an encapsulated long living fission reactor is driven by a proton accelerator, who produces neutrons on a target. In a first part we give the mathematical approach of such a sub-critical reactor, as an extension of the “Soliton Reactor” which was recently proposed by different authors, Edward Teller, L.P. Feoktistov, and others (H. Sekimoto under the name “Candle reactor”). In a second part we give results of simulations and explore the possibilities to control such a system.     

Resistance of Pseudomonas aeruginosa PAO1 phage F116 to sodium hypochlorite

The development of viral resistance to sodium hypochlorite was investigated using the Pseudomonas aeruginosa bacteriophage F116 as a model system. This phage was chosen because of its structural characteristics and former investigations conducted in this laboratory. F116 was shown to be sensitive to a sodium hypochlorite concentration of 0.0075 gl-1 (available chlorine) which produced a 5 log10 reduction in titre in a suspension test. Survival bacteriophages challenged with this sodium hypochlorite concentration were isolated, propagated and challenged again with the same and higher concentrations of the biocide. It was observed that progeny virions were becoming increasingly resistant to sodium hypochlorite challenges up to a concentration of 0.0175 gl-1 of available chlorine. It was also noticed that 1-2 log10 of F116 virions from resistant phage lysates remained sensitive to the biocide. An electron microscopical investigation of F116 resistant lysates showed that the phage resistance to sodium hypochlorite was not caused by F116 particles aggregation. Furthermore, no morphological difference between the sensitive and resistant F116 particles to sodium hypochlorite was identified.