Phytoplankton, such as diatoms, experience great variations of photon flux density (PFD) and light spectrum along the marine water column. Diatoms have developed some rapidly-regulated photoprotective mechanisms, such as the xanthophyll cycle activation (XC) and the non-photochemical chlorophyll fluorescence quenching (NPQ), to protect themselves from photooxidative damages caused by excess PFD...

Plants and algae have a love/hate relationship with light. As oxygenic photoautotrophic organisms, they require light for life; however, too much light can lead to increased production of damaging reactive oxygen species as byproducts of photosynthesis. In extreme cases, photooxidative damage can cause pigment bleaching and death, a phenomenon all too familiar to anyone who has tried to move a ...

Photochemical reactions of poly(3-butoxythiophene-2,5-diyl) with chloroform under irradiation with light were studied. The reactions were separately carried out under air, oxygen, and nitrogen. The obtained results showed that this reaction belongs to the pseudo-first-order reaction with a rate constant k(obs) of 1.4 x 10(-5) s(-1) at room temperature. The presence or absence of air, oxygen, an...

The response of sugar beet (Beta vulgaris L.) leaves to iron deficiency can be described as consisting of two phases. In the first phase, leaves may lose a large part of their chlorophyll while maintaining a roughly constant efficiency of photosystem II photochemistry; ratios of variable to maximum fluorescence decreased by only 6%, and photon yields of oxygen evolution decreased by 30% when ch...

Application of viruses as a carrier, though not safe, to deliver genes to eye tissue was successful. However, a safer, nonviral, biocompatible lipid-based nanoparticle has never been tested to treat blinding eye diseases. We created an artificial virus using a nanoparticle, liposome-protamine-DNA complex (LPD), modified with a cell permeable peptide and a nuclear localization signaling (NLS) pe...

The bottom-up construction and operation of machines and motors of molecular size is a topic of great interest in nanoscience, and a fascinating challenge of nanotechnology. The problem of the energy supply to make molecular machines work is of the greatest importance. Research in the last ten years has demonstrated that light energy can be used to power artificial nanomachines by exploiting ph...

the photocatalytic degradation of a common analgesic (acetaminophen) with titanium dioxide irradiated with low energy ultraviolet light (365 nm) was studied in order to determine the effect of several parameters such as catalyst’s weight, photochemical effect, and initial concentration. the results indicate that acetaminophen is degraded in the order of 4% by the photochemical effect. the pres...

The preparation and photophysical properties of a number of water-soluble metallated phthalocyanines are described. These compounds have been shown to be effective photosensitizers for the destruction of tumours. The photophysics of various aluminium phthalocyanines of different degrees of sulphonation, from mono (S1) to tetra (S4); and of various disulphonated (S2) regioisomers was shown to be...

PURPOSE Photochemical internalization is under development for improving macromolecular therapy by inducing photochemical damage to endocytic vesicles. This damage leads to the release of therapeutic macromolecules entrapped in endocytic vesicles into the cytosol. The macromolecules may in this way be able to interact with therapeutic targets instead of being degraded by lysosomal hydrolases. B...

In response to excessive light, the thylakoid membranes of higher plant chloroplasts show dynamic changes including the degradation and reassembly of proteins, a change in the distribution of proteins, and large-scale structural changes such as unstacking of the grana. Here, we examined the aggregation of light-harvesting chlorophyll-protein complexes and Photosystem II core subunits of spinach...