Närståendes upplevelse av att leva med en person med Parkinsons sjukdom

Validerat; 20101217 (root

Lustfyllt skrivande : att öka elevers motivation

Validerat; 20101217 (root

Picosecond Transient Absorption of Xanthene Dyes

After one- and two-colour ps-excitation the transient absorption of rose bengal, erythrosin B and eosin Y in the spectral range from 450 to 670 nm was probed using picosecond continuum pulses generated in H$\text{}_{2}$O-D$\text{}_{2}$O mixture. Our experiments showed for all dyes a high T$\text{}_{1}$-T$\text{}_{n}$ absorption signal above 590 nm where no ground state absorption occurs. These excited triplet states can be effectively populated by a delayed second pump pulse. Their properties with special attention to reverse intersystem crossing processes from T$\text{}_{n}$ to S$\text{}_{x}$ are discussed

Physical and chemical properties of pyropheophorbide)a-methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-L-a-phosphatidylcholine vesicles

The aggregation process of pyropheophorbide-a methyl ester (PPME), a second generation hotosensitizer, was investigated in various solvents. Absorption and fluorescence spectra showed that the photosensitizer was under a monomeric form in ethanol as well as in dimyristoyl-L-α-phosphatidylcholine liposomes while it was strongly aggregated in phosphate buffer. A quantitative determination of reactive oxygen species production by PPME in these solvents has been undertaken by electron spin resonance associated with spin trapping technique and absorption spectroscopy. In phosphate buffer, both electron spin resonance and absorption measurements led to the conclusion that singlet oxygen production was not detectable while hydroxyl radical production was very weak. In liposomes and ethanol, singlet oxygen and hydroxyl radical production increased highly; the singlet oxygen quantum yield was determined to be 0.2 in ethanol and 0.13 in liposomes. The hydroxyl radical production origin was also investigated. Singlet oxygen was formed from PPME triplet state deactivation in presence of oxygen. Indeed, the triplet state formation quantum yield of PPME was found to be about 0.23 in ethanol, 0.15 in liposomes (too small to be measured in PBS)