Influence of Titanium Dioxide Pigments on the Photodegradation of Paraloid Acrylic Resin
AbstractMarble and stone used as building materials are susceptible to environmental damage. Polymers can be used as carriers of suitable pigments for the protection of the surface of a monument. The photodegradation of a series of Paraloid B72 films containing titanium dioxide (TiO2) pigments has been studied under UV irradiation. Two kinds of TiO2, anatase and anatase/rutile mixture, were used in different concentrations, 5, 15 and 30% w/w. The chemical and molecular changes induced by the irradiation treatment were followed by Fourier transform infrared spectroscopy, gel permeation chromatography, and solubility measurements. The presence of anatase pigment significantly improved the photostability of Paraloid films
The long-term prognosis of Takayasu's disease depends on an elective surgical treatment which requires full and accurate assessment of the lesions. We present here a retrospective study of 50 patients explored before surgery by intra-arterial digital angiography. In 92 percent of the patients the thoraco-abdominal aorta and its branches were well documented on 2 orthogonal projections performed in one single session. The high-quality intra-arterial opacification made it possible to detect incipient parietal lesions and to evaluate the lesions of the small caliber branches and the downstream bed in case of occlusion. These advantages, and the absence of morbidity in our experience, make digital panarteriography a method of choice to evaluate Takayasu's disease.