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The influence of molecular architecture on light-induced SRG formation was investigated. Polymers with different degree of branching were synthesized by ATRP and functionalized with azobenzene chromophores. The polymers differ only in their architecture - linear, 4-, 6-, or 12-arms stars. The photo-induced dichroism as well as the efficiency of SRG formation was similar for all polymers of this series. New consideration for the origin of the driving force was used to explain this behavior. The comparable SRG inscription rate in differently branched polymers can be rationalized by assuming that azobenzene acts as an internal molecular motor and can cause a non-turbulent motion on a scale smaller than that on which normal entanglement restriction forces act.

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The influence of the azobenzene concentration on the photo-induced surface relief grating (SRG) formation in polymer films was investigated. Two series of polymers with 4-alkoxy-4'-cyanoazobenzene side groups were synthesized. In series A, the degree of substitution was varied, while in series B, azobenzene and biphenyl groups were introduced in varying composition, but the concentration of non-reacted HEMA-groups was kept constant. Photo-induction of the dichroism and the SRG was studied as function of the azobenzene concentration. An optimum was found for the SRG formation (76%), while the highest dichroism was induced at the lowest azobenzene concentration of 20%. The restriction of rotational and translational molecular motions observed at higher azobenzene concentration was explained by pi-pi stacking of the azobenzene moieties and interaction of unreacted HEMA groups.

The RP Annual Report summarises the activities carried out by CERN’s Radiation Protection Group in the year 2003. It includes contribution from the EN section of the TIS/IE Group on environmental monitoring. Chapter 1 reports on the measurements and estimations of the impact on the environment and public exposure due to the Organisation’s activities. Chapter 2 provides the results of the monitoring of CERN’s staff, users and contractors to occupational exposure. Chapter 3 deals with operational radiation protection around the accelerators and in the experimental areas. Chapter 4 reports on RP design studies for the LHC and CNGS projects. Chapter 5 addresses the various services provided by the RP Group to other Groups and Divisions at CERN, which include managing radioactive waste, high-level dosimetry, lending radioactive test sources and shipping radioactive materials. Chapter 6 describes activities other than the routine and service tasks, i.e. development work in the field of instrumentation and research and support activities for future CERN projects or in RP-related domains.

A fusion protein containing a B cell lymphoma idiotype (Id) and granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent stimulator of tumor immunity. In three different tumor models we show that immunization with autologous lymphoma cells that have been engineered to express the Id in the context of GM-CSF is much more effective than immunization with an equivalent dose of the purified protein. The lymphoma Id could be modified by introducing the GM-CSF gene into the immunoglobulin (Ig) heavy chain locus via gene targeting. This approach circumvents the isolation of the rearranged immunoglobulin variable genes from the tumor and the preparation of tumor-specific vector constructs. The low production of Id/GM-CSF fusion proteins by transfected cells, which is a major obstacle in the use of purified fusion proteins for immunotherapy, is due to the presence of the cytokine gene in the immunoglobulin locus. Low production, however, is not limiting in the cell-based setting, because upon in vivo administration of the modified autologous cells, even minute expression levels are sufficient to induce tumor immunity.

Factors influencing the thickness of polypeptide layers grafted from self-assembled monolayers were investigated by varying the initiator site density and the reactivity of the N-carboxyanhydride monomer. To vary the density of initiating sites and to match the steric requirements of the growing polymer chain, mixed self-assembled monolayers were prepared with terminal amino groups. These SAMs were prepared by coadsorption of bromine- and methyl-terminated silanes and a subsequent in-situ modification. Polymerization experiments with these SAMs reveal an influence of initiator site density on the polymer layer thickness. SAMs prepared with 60% functionalized silane showed an optimum thickness. The variation in layer thickness due to the variation of initiator site density is smaller than the influence of the monomer reactivity.