Multifunctional Luminescent Down‐Shifting Fluoropolymer Coatings: A Straightforward Strategy to Improve the UV‐Light Harvesting Ability and Long‐Term Outdoor Stability of Organic Dye‐Sensitized Solar Cells

A new multifunctional coating for photovoltaic cells incorporating light‐management, UV‐protection, and easy‐cleaning capabilities is presented. Such coating consists of a new photocurable fluorinated polymer embedding a luminescent europium complex that acts as luminescent down‐shifting (LDS) material converting UV photons into visible light. The combination of this system with ruthenium‐free organic dye‐sensitized solar cells (DSSCs) gives a 70% relative increase in power conversion efficiency as compared with control uncoated devices, which is the highest efficiency enhancement reported to date on organic DSSC systems by means of a polymeric LDS layer. Long‐term (>2000 h) weathering tests in real outdoor conditions reveal the excellent stabilizing effect of the new coating on DSSC devices, which fully preserve their initial performance. This excellent outdoor stability is attributed to the combined action of the luminescent material that acts as UV‐screen and the highly photostable, hydrophobic fluoropolymeric carrier that further prevents photochemical and physical degradation of the solar cell components. The straightforward approach presented to simultaneously improve performance and outdoor stability of DSSC devices may be readily extended to a large variety of sensitizer/luminophore combinations, thus enabling the fabrication of highly efficient and extremely stable DSSCs in an easy and versatile fashion.     

Mechanisms of guanosine triphosphate hydrolysis by Ras and Ras-GAP proteins as rationalized by ab initio QM/MM simulations

The hydrolysis reaction of guanosine triphosphate (GTP) by p21(ras) (Ras) has been modeled by using the ab initio type quantum mechanical-molecular mechanical simulations. Initial geometry configurations have been prompted by atomic coordinates of the crystal structure (PDBID: 1QRA) corresponding to the prehydrolysis state of Ras in complex with GTP. Multiple searches of minimum energy geometry configurations consistent with the hydrogen bond networks have been performed, resulting in a series of stationary points on the potential energy surface for reaction intermediates and transition states. It is shown that the minimum energy reaction path is consistent with an assumption of a two-step mechanism of GTP hydrolysis. At the first stage, a unified action of the nearest residues of Ras and the nearest water molecules results in a substantial spatial separation of the gamma-phosphate group of GTP from the rest of the molecule (GDP). This phase of hydrolysis process proceeds through the low barrier (16.7 kcal/mol) transition state TS1. At the second stage, the inorganic phosphate is formed in consequence of proton transfers mediated by two water molecules and assisted by the Gln61 residue from Ras. The highest transition state at this segment, TS3, is estimated to have an energy 7.5 kcal/mol above the enzyme-substrate complex. The results of simulations are compared to the previous findings for the GTP hydrolysis in the Ras-GAP (p21(ras)-p120(GAP)) protein complex. Conclusions of the modeling lead to a better understanding of the anticatalytic effect of cancer causing mutation of Gln61 from Ras, which has been debated in recent years.     

A Sea Under Siege – Alien Species in the Mediterranean

Exotic macrophytes, invertebrates and fish are found in most coastal habitats in the Mediterranean Sea. The Mediterranean Sea has been subjected to introductions of non-indigenous species by ship traffic since the opening of interoceanic maritime routes five centuries ago. The Sea, a hub of shipping, is exceptionally susceptible to invaders that arrive in fouling communities or ballast. The Suez Canal has been the largest pathway for the entry of these species: more than 300 Erythrean species – principally molluscs, fish, decapod crustaceans, polychaetes and algae – have become established in the eastern Mediterranean, primarily along the Levantine coasts. Mariculture of nonindigenous shellfish predominates in the northern Mediterranean lagoonar environments. Unrestricted transport of commercially important exotic shellfish has resulted in numerous unintentional introductions of pathogens, parasites and pest species. Some invaders have outcompeted or replaced native species locally, severely reducing biodiversity; some other invaders are so abundant they are exploited commercially. The rate of these biotic invasions has increased in recent decades, and they collectively have significant ecological and economic impacts in the Mediterranean Sea. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mislabeled: eco-labeling an invasive alien shellfish fishery

The invasive alien Manila clam fishery from Ria Arousa, Spain, was recommended for a Marine Stewardship Council certificate which implies the fishery maintains the integrity of the ecosystem. By certifying an environmentally harmful invasive alien clam fishery, the MSC harms the environment and risks its credibility, at the time when environmental responsibility and social responsibility are increasingly important to policymakers, industry, and consumers, particularly in Europe. We call on the MSC to reassess their evaluation of the Ruditapes philippinarum fishery in Ria Arousa, Spain.     

Late modifications of simian virus 40 chromatin during the lytic cycle occur in an immature form of virion

Two main modifications of the simian virus 40 chromatin were found to occur during the lytic cycle. One was the progressive increase in the acetylation level in the four non-H1 histones as the 75S deoxynucleoprotein complexes (minichromosomes) became assembled into heavier structures. The other was the final elimination from viral chromatin of histone H1. An important stage in the course of these changes was represented by an intracellular simian virus 40 particle, in which the virus-coded proteins were already assembled, but properties distinct from those of mature virions were still present. This particle resembled the mature virions in morphology, sedimentation rate, and buoyant density. It was distinguished by the instability, the presence of histone H1, the uptake of radioactive acetate, and the lower infectivity. Its significance appears to be that of an immature virion on the basis of these characters and of the consistent kinetic behavior during the lytic cycle.     

Structural studies of two rhinovirus serotypes complexed with fragments of their cellular receptor

Two human rhinovirus serotypes complexed with two- and five-domain soluble fragments of the cellular receptor, intercellular adhesion molecule-1, have been investigated by X-ray crystallographic analyses of the individual components and by cryo-electron microscopy of the complexes. The three-dimensional image reconstructions provide a molecular envelope within which the crystal structures of the viruses and the receptor fragments can be positioned with accuracy. The N-terminal domain of the receptor binds to the rhinovirus 'canyon' surrounding the icosahedral 5-fold axes. Fitting of molecular models into the image reconstruction density identified the residues on the virus that interact with those on the receptor surface, demonstrating complementarity of the electrostatic patterns for the tip of the N-terminal receptor domain and the floor of the canyon. The complexes seen in the image reconstructions probably represent the first stage of a multistep binding process. A mechanism is proposed for the subsequent viral uncoating process.     

Sequence dependent conformational variations of collagen triple-helical structure.

The 2 A crystal structure reported here of the collagen-like model peptide, T3-785, provides the first visualization of how the sequence of collagen defines distinctive local conformational variations in triple-helical structure.     

Short-term magnesium deficiency upregulates sphingomyelin synthase and p53 in cardiovascular tissues and cells: relevance to the de novo synthesis of ceramide

The present study tested the hypotheses that 1) short-term dietary deficiency of magnesium (21 days) in rats would result in the upregulation of sphingomyelin synthase (SMS) and p53 in cardiac and vascular (aortic) smooth muscles, 2) low levels of Mg(2+) added to drinking water would either prevent or greatly reduce the upregulation of both SMS and p53, 3) exposure of primary cultured vascular smooth muscle cells (VSMCs) to low extracellular Mg(2+) concentration ([Mg(2)](o)) would lead to the de novo synthesis of ceramide, 4) inhibition of either SMS or p53 in primary culture VSMCs exposed to low [Mg(2+)](o) would lead to reductions in the levels of de novo ceramide synthesis, and 5) inhibition of sphingomyelin palmitoyl-CoA transferase (SPT) or ceramide synthase (CS) in primary cultured VSMCs exposed to low [Mg(2+)](o) would lead to a reduction in the levels of de novo ceramide synthesis. The data indicated that short-term magnesium deficiency (10% normal dietary intake) resulted in the upregulation of SMS and p53 in both ventricular and aortic smooth muscles; even very low levels of water-borne Mg(2+) (e.g., 15 mg·l(-1)·day(-1)) either prevented or ameliorated the upregulation in SMS and p53. Our experiments also showed that VSMCs exposed to low [Mg(2+)](o) resulted in the de novo synthesis of ceramide; the lower the [Mg(2+)](o), the greater the synthesis of ceramide. In addition, the data indicated that inhibition of either SMS, p53, SPT, or CS in VSMCs exposed to low [Mg(2+)](o) resulted in marked reductions in the de novo synthesis of ceramide.