After a systematic analysis of different databases and a comparison with empirical data, we decided to describe photoelectric absorption coefficients, coherent and incoherent scattering coefficients and mass attenuation coefficients in the energy range from 1 to 300 keV for elements from Z = 1 to 94 by a modified version of Scofield's tables in combination with scattering coefficients from Elam et al. Modifications include check and correction of edge positions, description of M 4 -and M 5 -ranges of elements from promethium upwards by sawtooth responses and reduction of data by introduction of least-squares fits of fifth order to Scofield's and Elam et al.'s numerical data. Our database was developed especially for application in fundamental parameter programs for quantitative x-ray analysis (XRFA, EPMA, XPS and TEY).We start by looking at the classical McMaster tables. 2 Elements from Z D 1 to 83 and elements Z D 86, 90, 92 and 94 are contained and photon energies cover the range from 1 keV to 1 MeV. Essential data are conversion from b/a to cm 2 g 1 , K-and L-edge positions and corresponding jumps, third-order least-squares fit coefficients of photoelectric absorption in K-, second-order fit coefficients in L-and

CD155, originally known as the cellular receptor for poliovirus, is the founding member of a subfamily of immunoglobulin‐like adhesion receptors. Apart from its function in establishing adherens junctions between contacting epithelial cells, the engagement of CD155 with two recently identified ligands, CD226 and CD96, mediates immunologically relevant processes such as NK cell‐driven killing of tumor cells in humans. Here we report on the generation and immunological analysis of mice constitutively deficient of CD155. Moreover, the expression profile of CD155 on hematopoietic cells has been determined using newly established antibodies. CD155‐deficient mice develop normally without displaying an overt phenotype. However, the animals are distinguished by distinct deficits in the development of a regular humoral immune response. Whereas systemic challenges revealed no differences, orally administered antigen evoked less efficient IgG and IgA antibody responses despite of normal IgM titers when compared to wild‐type mice. Therefore, CD155 may assist in an efficient humoral immune response generated within the intestinal immune system.

An efficient method for quantitative XPS analysis is the so-called multiline approach. This method does not require standards, it takes into account the instrumental and matrix effects and it derives quantitative information from statistical analysis of all photoelectron intensities visible in the spectra. One can expect the reliability of this approach to be better than the reliability of methods involving uncorrected relative sensitivity factors. This paper summarizes recent improvements in the multiline approach. In particular, a new expression for the universal energy dependence of the inelastic mean free path is currently used. Furthermore, the statistical analysis has been modified in order to account properly for the error in the countrates. Finally, a database with physical constants has been added (photoionization cross-sections, asymmetry parameters, binding energies, etc.) to avoid errors of polynomial approximations. The modified algorithm of the multiline approach was applied to photoelectron intensities measured for AuCu alloys in four laboratories. Surfaces of these alloys were sputtered with 2 keV Ar' ions, because at this energy the selective sputtering effects are expected to be negliible. Very consistent results were obtained. The average deviation from the hulk surface composition was found to be equal to k3.2 at.%. Extensive software implementing the described version of the multiline approach is presently being developed.

Ultrathin SiO 2 films with thicknesses between 0.3 and 8 nm were grown on native silicon (Si/SiO 2 ), muscovite mica and polycrystalline gold substrates via repeated application of a binary reaction sequence, which involved the formation of a self-assembled alkylsiloxane monolayer (step A) and UV-ozone oxidation of the hydrocarbon groups (step B). Using octadecyltrichlorosilane as a precursor, SiO 2 films could be grown in a strictly linear, layer-by-layer mode on each of the three substrates with a growth rate of 3.0 ( 0.3 Å per deposition cycle, which corresponds to a monolayer of SiO 2 . The properties of these oxide films (composition, structure, packing density) were found to be essentially identical and independent of the substrate, as evidenced by ellipsometry, infrared reflection, and X-ray photoelectron spectroscopy. Furthermore, the quality of the oxide layers was investigated as a function of the hydrocarbon chain length of the alkylsiloxane monolayer formed in step A, using four different alkyltrichlorosilanes, R-SiCl 3 (R ) C 18 H 37 , C 11 H 23 , C 4 H 9 , CH 3 ), as precursors. For each compound, a linear increase of the SiO 2 film thickness with the number of applied deposition cycles was again observed, but the growth rate increased noticeably from 2.8 Å/cycle for the C 18 and the C 11 compound to 3.2 Å/cycle and 6.5 Å/cycle for the C 4 and the C 1 compound, respectively, concomitant with an increase of the surface roughness in atomic force microscopy images of the oxide films. The packing density of the Si atoms in these films remains essentially constant for longer-chain precursors (R g C 4 ), although the structure of the hydrocarbon layer changes drastically from a highly-ordered, perpendicular alignment on the surface (R ) C 18 ) to a random, isotropic arrangement (R e C 11 ). For films prepared from shorter precursors (R < C 4 ), however, multilayer formation sets in and results in film growth rates clearly beyond the monolayer level. A minimum chain length of about four C atoms is therefore required to restrict the alkylsiloxane film formation (step A) to the monolayer level and to provide reproducible and precise control of the oxide film thickness in this deposition process.

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A photochemical technique for the modification of polyethylene (PE) surfaces was developed. Polyethylene samples were irradiated with UV light in a gas atmosphere containing SO2 and air to achieve a photosulfonation of the surface. The introduction of sulfonic acid groups (−SO3H) onto the PE surface was proved by Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The influence of the gas composition and the UV irradiation time on the modification reaction were studied by means of contact angle measurements, FTIR spectroscopy, and dyeing with methylene blue. The hydrophilicity of the PE surface increased considerably compared to unreacted PE. The depth of photomodification amounted to several micrometers. A patterned surface modification was obtained by mask projection. The presented method of surface modification is carried out under atmospheric pressure and is considered to be an inexpensive alternative to plasma modification techniques. Because of the large depth of modification, the process may also be useful for the modification of membranes andin combination with projection lithographyfor the manufacture of gratings in thin polymer films (as required for holographic recordings and distributed feedback lasers).

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