Although it is established that defective clearance and, hence, increased accumulation of apoptotic cells can lead to autoimmunity, the mechanism by which this occurs remains elusive. Here, we observed that apoptotic cells undergoing secondary necrosis but not intact apoptotic cells provoked substantial immune responses, which were mediated through the toll-like receptor 2 (TLR2) pathway. The development of autoimmune diabetes was markedly inhibited in Tlr2(-/-) mice but not in Tlr4(-/-) mice, showing that TLR2 plays an important role in the initiation of the disease. Apoptotic beta-cell injury could stimulate the priming of diabetogenic T cells through a TLR2-dependent, but TLR4-independent, activation of antigen-presenting cells. These findings suggest that beta-cell death and its sensing via TLR2 may be an initial event for the stimulation of antigen-presenting cells and development of autoimmune diabetes.

The influence of high-energy e-beam treatment at atmospheric pressure on the structure and photocatalytic activity of TiO 2 was examined. Using an e-beam energy of 1 MeV and exposure in the range of 5-15 kGy, an improvement in the photocatalytic activity of TiO 2 was observed. An increase in the population of C-O bonds was found in the C and O 1s states using X-ray Photoelectron Spectroscopy (XPS) suggesting that the change in the structure of the C impurities on the surface of TiO 2 is closely related to the variation in the photocatalytic activity.

The CO oxidation activity of Pt deposited on Ta 2 O 5 /Ta was studied with various amounts of Au postdeposited on Pt/Ta 2 O 5 /Ta. For Pt nanoparticles with a mean size of 2-4 nm, an enhancement in the CO oxidation activity with increasing amount of post-deposited Au was found. The mixed Au-Pt nanoparticles with sizes in the range of 2-4 nm exhibited higher stability than the bare Au nanoparticles with a similar size range. In contrast to the results obtained with the Pt nanoparticles, the catalytic activity of a thicker Pt film gradually decreased with increasing amount of Au deposited. Based on the CO desorption experiments, it is suggested that the surface of the catalytically active Au-Pt bimetallic structures consists of both Au and Pt sites.

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