An Efficient Thiol‐Ene Chemistry for the Preparation of Amphiphilic PHA‐Based Graft Copolymers

We present a straightforward method to prepare amphiphilic graft copolymers consisting of hydrophobic poly(3‐hydroxyalkanoates) (PHAs) backbone and hydrophilic α‐amino‐ω‐methoxy poly(oxyethylene‐co‐oxypropylene) (Jeffamine®) units. Poly(3‐hydroxyoctanoate)‐co‐(3‐hydroxyundecenoate) (PHOU) was first methanolyzed to obtain the desired molar mass. The amino end groups of Jeffamine were converted into thiol by a reaction with N‐acetylhomocysteine thiolactone and subsequently photografted. This “one‐pot” functionalization prevents from arduous and time‐consuming functionalization of the hydrophilic precursor or tedious modifications of PHAs, thus simplifying the process. The amphiphilic nature of modified PHAs leads to water‐soluble copolymers exhibiting thermoresponsive behavior.     

A quasi-optimal convergence result for fracture mechanics with XFEM

The aim of this Note is to give a convergence result for a variant of the eXtended Finite Element Method (XFEM) on cracked domains using a cut-off function to localize the singular enrichment area. The difficulty is caused by the discontinuity of the displacement field across the crack, but we prove that a quasi-optimal convergence rate holds in spite of the presence of elements cut by the crack. The global linear convergence rate is obtained by using an enriched linear finite element method. To cite this article: E. Chahine et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

General description of new physics in t,b and boson interactions and its unitarity constraints

We list all possible dim = 6 CP conserving and SU(3) × SU(2) × U(1) gauge invariant interactions, which could be generated in case no new particles would be reachable in the future Colliders, and the only observable New Physics would be in the form of new interactions affecting the scalar sector and the quarks of the third family. These interactions are described by operators involving the standard model scalar field, the quarks of the third family and the gauge bosons. Subsequently, we identify those operators which do not contribute to LEP1 (and lower energy) observables at tree level and are not purely gluonic. Since present measurements do not strongly constrain the couplings of these operators, we derive here the unitarity bounds on them. Finally, in order to get a feeling on the possible physical meaning of the appearance of any of these operators, we identify the operators generated in a class of renormalizable dynamical models which at the TeV scale, are fully described by the SU(3) × SU(2) × U(1) gauge group.     

Signatures of anomalous couplings in boson pair production throughγγ collisions

We discuss possible New Physics (NP) effects on the processesγγ →W ⁺ W ⁻,ZZ, Zγ, γγ, HH which are observable inγγ collisions. Such collisions may be achieved through laser backscattering at a high energye ⁺ e ⁻ linear collider. To the extent that no new particles will be directly produced in the future colliders, it has already been emphasized that the new physics possibly hidden in the bosonic interactions, may be represented by the sevendim=6 operatorsO _W,O _BΦ,O _WΦ,O _UB,O _UW and (the last two ones being CP-violating). In this paper, we show that the above processes are sensitive to NP scales at the several TeV range, and we subsequently discuss the possibility to disentangle the effects of the various operators. Partially supported by the EC contract CHRX-CT94-0579     

Novel biodegradable copolyesters containing blocks of poly(3-hydroxyoctanoate) and poly(epsilon-caprolactone): synthesis and characterization

Novel biodegradable polyester block copolymers have been synthesized by using well-defined poly(3-hydroxyoctanoate) (PHO) oligomers having a hydroxyl end group and an ester end group with M(n) values of 800, 2,500, 5,300, 8,000, or 20,000 as an elastomeric soft segment and poly(epsilon-caprolactone) as a more crystalline segment. These PHO oligomers prepared by methanolysis were subjected to block copolymerization with epsilon-caprolactone. The chemical structure of the copolymers was confirmed by (1)H NMR and (13)C NMR spectroscopy. All the copolyesters are semi-crystalline and two T(g) were observed by differential scanning calorimetry when the molecular weight of the PHO block is about 20,000.     

Chromatographic study of the adsorption kinetics of albumin on monoclonal and polyclonal immunoadsorbents

Summary High-performance liquid chromatography (HPLC) has been used to study the adsorption kinetics of proteins on immunoadsorbents. The adsorption rate constant of human serum albumin (HSA) on monoclonal and polyclonal anti-HSA antibodies immobilized on a silica HPLC support was determined by saturating the column with repeated pulse injections. Studies on polyclonal immunodsorbents of different capacities enable evaluation of the contribution of transport to the binding sites. The adsorption properties of two different monoclonal anti-HSA antibodies immobilized on a chromatographic support were characterized by different approaches. The location of the epitope on the HSA molecule was determined by enzyme-linked immunoassay (ELISA) with albumin fragments. The chromatographic method was used to determine the column capacity and the adsorption rate constant of HSA on the immunoadsorbent. To compare the affinity of the antibodies for the antigen, an indirect ELISA method was used to determine the equilibrium constant of antigen-antibody association in solution Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th september, 1996.