SUMMARY The vinylic polymerization of norbornene and its copolymerization with norbornene carboxylic acid methyl esters were investigated. Norbornene was polymerized by us using di-p-chloro-bis-(6-methoxybicyclo[2.2.l]hept-2-ene-endo-5o,2x)-palladium(II) as catalyst. The polymerization time can be decreased by a factor of 100000 by activation of the catalyst with methylaluminoxane (MAO). With this palladium catalyst activated by MAO, 140 t of norbornene can be polymerized per mol palladium per h. This catalyst system was much more active than [Pd(CH3CN)4](BF4), (I). The polymerization of norbornene by (6-methoxybicyclo[2.2.1]hept-2-ene-endo-5o,2x)-palladium(II) tetrafluoroborate was also possible but it was not as fast as the polymerization by Pd catalysts activated with MAO. We were also able to obtain copolymers of norbornene and 5-norbornene-2-carboxylic acid methyl ester (exdendo = 1/4 or 2/3) containing between 15 and 20 mol-% ester units. The copolymerization of norbornene and 2-methyl-5-norbornene-2-carboxylic acid methyl ester (exdendo = 7/3) was faster than the copolymerization mentioned before. In contrast the homopolymerization of 2-methyl-5-norbornene-2-carboxylic acid methyl ester was 10 times slower than that of 5-norbornene-2-carboxylic acid methyl ester (exdendo = 1/4).

The vinylic polymerization of 5-norbornene-2-carboxylic esters with different palladium catalysts to polymers of high molecular weights is reported. Computer simulations based on a force field approach show that these polymers display a rigid statistical chain conformation and are thus a further example of rotationally strongly constrained polymers. The polymers are soluble in a variety of solvents despite their rigidity, they are amorphous, possess glass transition temperatures well above 250°C, and have a high packing density. The dipoles located in the lateral groups perform a secondary relaxation process similar to the case of flexible or rigid rod-like polymers containing ester groups. Acta Polymer., 48,385-391 Q VCH Verlagsgesellschaft mbH, D-69451 Weinheim 1997 0323-7648/97/0808-0385$17.50+.50/0 385

The vinylic polymerization of norbornene and its copolymerization with norbornene carboxylic acid methyl esters were investigated. Norbornene was polymerized by us using di‐μ‐chloro‐bis‐(6‐methoxybicyclo[2.2.1]hept‐2‐ene‐endo‐5σ,2π)‐palladium(II) as catalyst. The polymerization time can be decreased by a factor of 100000 by activation of the catalyst with methylaluminoxane (MAO). With this palladium catalyst activated by MAO, 140 t of norbornene can be polymerized per mol palladium per h. This catalyst system was much more active than [Pd(CH3CN)4](BF4)2 (I). The polymerization of norbornene by (6‐methoxybicyclo[2.2.1]hept‐2‐ene‐endo‐5σ,2π)‐palladium(II) tetrafluoroborate was also possible but it was not as fast as the polymerization by Pd catalysts activated with MAO. We were also able to obtain copolymers of norbornene and 5‐norbornene‐2‐carboxylic acid methyl ester (exo/endo = 1/4 or 2/3) containing between 15 and 20 mol‐% ester units. The copolymerization of norbornene and 2‐methyl‐5‐norbornene‐2‐carboxylic acid methyl ester (exo/endo = 7/3) was faster than the copolymerization mentioned before. In contrast the homopolymerization of 2‐methyl‐5‐norbornene‐2‐carboxylic acid methyl ester was 10 times slower than that of 5‐norbornene‐2‐carboxylic acid methyl ester (exo/endo = 1/4).

Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis in neonates and is also the causative agent of several serious infections in immunocompromised adults. S. agalactiae encounters multiple niches during an infection, suggesting that regulatory mechanisms control the expression of specific virulence factors in this bacterium. The present study describes the functional characterization of a gene from S. agalactiae, designated rga, which encodes a protein with significant similarity to members of the RofA-like protein (RALP) family of transcriptional regulators. After deletion of the rga gene in the genome of S. agalactiae, the mutant strain exhibited significantly reduced expression of the genes srr-1 and pilA, which encode a serine-rich repeat surface glycoprotein and a pilus protein, respectively, and moderately increased expression of the fbsA gene, which encodes a fibrinogen-binding protein. Electrophoretic mobility shift assays demonstrated specific DNA binding of purified Rga to the promoter regions of pilA and fbsA, suggesting that Rga directly controls pilA and fbsA. Adherence assays revealed significantly reduced binding of the Δrga mutant to epithelial HEp-2 cells and to immobilized human keratin 4, respectively. In contrast, the adherence of the Δrga mutant to A549 cells and its binding to human fibrinogen was significantly increased. Immunoblot and immunoelectron microscopy revealed that the quantity of pilus structures was significantly reduced in the Δrga mutant compared with the parental strain. The wild-type phenotype could be restored by plasmid-mediated expression of rga, demonstrating that the mutant phenotypes resulted from a loss of Rga function.

Stimuli-responsive water soluble acrylamide polymers which exhibit a lower critical solution temperature (LCST), or an upper critical solution temperature (UCST) were prepared by free radical polymerization, or by chemical modification of precursor polymers. The obtained nonionic thermosensitive polymers are employed for the preparation of thin hydrogel films on gold surfaces. Two different strategies were studied. The first one consists of the immobilization of polymers functionalized with disulfide end-groups onto gold (grafting to). The second strategy consists of the immobilization of a disulfide functionalized initiator followed by the polymeriza tion in situ from gold surfaces (grafting from). The grafting reactions in water or in ethanol were followed by surface plasmon resonance (SPR), ellipsometry and contact angle measurements. 162