Effect of Some Macrocyclic Ligands on the Rate of Reduction of Perchlorate Ion by Titanium(III)

Complexation with cyclam increases the rate of reduction of perchlorate ion by TiIII (in acidic, aqueous, 4 mol dm-3 LiCl Solutions at 25 °C) relative to the rate of the corresponding reduction of Ti3+. A modified cyclam with pendant amine and p-aminobenzyl functional groups is more effective in this regard than is cyclam itself. Both redox reactions are acid catalyzed. The data is consistent with involvement of an intermediate containing two TiIII centers

DNA cleavage and binding selectivity of a heterodinuclear Pt–Cu(3-Clip-Phen) complex

The synthesis and nuclease activity of a new bifunctional heterodinuclear platinum–copper complex are reported. The design of this ditopic coordination compound is based on the specific mode of action of each component, namely, cisplatin and Cu(3-Clip-Phen), where 3-Clip-Phen is 1-(1,10-phenanthrolin-3-yloxy)-3-(1,10-phenanthrolin-8-yloxy)propan-2-amine. Cisplatin is not only able to direct the Cu(3-Clip-Phen) part to the GG or AG site, but also acts as a kinetically inert DNA anchor. The nuclease activity of this complex has been investigated on supercoiled DNA. The dinuclear compound is not only more active than Cu(3-Clip-Phen), but is also capable of inducing direct double-strand breaks. The sequence selectivity of the mononuclear platinum complex has been investigated by primer extension experiments, which reveal that its interaction with DNA occurs at the same sites as for cisplatin. The Taq polymerase recognizes the resulting DNA damage as different from that for unmodified cisplatin. The sequence-selective cleavage has been investigated by high-resolution gel electrophoresis on a 36-bp DNA fragment. Sequence-selective cleavages are observed in the close proximity of the platinum sites for the strand exhibiting the preferential platinum binding sites. The platinum moiety also coordinates to the other DNA strand, most likely leading only to mono guanine or adenine adducts

Simulation of GEMASOLAR-based solar tower plants for the Chinese energy market: Influence of plant downsizing and location change.

In many countries that are experiencing a steep increase of energy demand, there is a growing challenge of responding to this demand by investing in renewable technologies for new power plants. Solar energy seems to be one of the best solutions to reduce the fossil fuels consumption for energy production purposes. In terms of high-power solar plants, concentrating towers are characterized by high efficiencies, but the investment costs are high as well. For this reason, a fundamental issue consists in simulating the solar tower behavior in different locations, in order to provide a precise estimation of both annual energy production and return of the investment. Among these types of solar plants, GEMASOLAR has been recently (2011) put in operation in Andalusia, Spain, and the data that have been obtained by this plant allow one to study its potential for application in different locations. The present work is aimed at simulating the GEMASOLAR plant behavior in some Chinese areas suitable for such a technology. All the simulations proposed here have been obtained through a Solar Advisor Model (SAM). Some of the simulations of the original plant have been modified forcing the plant to run without fossil fuel hybridization or changing its nominal power. After model validation, results have shown encouraging perspectives for the exploitation of this technology in China, with annual overall efficiencies of 14% for the 20 MW power plant (GEMASOLAR nominal power). In addition, the down-scaled plants have been optimized through native SAM software algorithm focusing on geometrical parameters. This procedure has been proved to be able of maintaining a high efficiency (14.97%) even for a 10 MW power plant. The focus has been on pilot plants, since they could represent the first step towards a deep exploitation of concentrating solar thermal power in China, with a relatively low capital risk

Folding propensity and biological activity of peptides: New insights from conformational properties of a novel peptide derived from Vitreoscilla haemoglobin

The synthetic peptide Vitr-p-13(YPIVGQELLGAIK-NH2), derived from the bacterial dimeric Vitreoscilla haemoglobin (VHb) in the position 95-107, is characterized by a preeminent "statistical coil" conformation in water as demonstrated by CD experiments and long time-scale MD simulations. In particular, Vitr-p-13 does not spontaneously adopt an alpha-helix folding in Water, but it is rather preferentially found in beta-hairpin-like conformations. Long time-scale MD simulations have also shown that Vitrp-13 displays a "topological-trigger" which initiates alpha-helix folding within residues 7-10, exactly like seen in the temporins, a group of linear, membrane-active antimicrobial peptides of similar length. At variance with temporins, in Vitr-p-13 such a process is energetically very demanding (+ 10 kJ/mol) in water at 300 K, and the peptide was found to be unable to bind model membranes in vitro and was devoid of antimicrobial activity. The present results,, compared with previous studies on similar systems, strengthen the hypothesis of the requirement Of a partial folding when still in aqueous environment to allow a peptide to interact with cell-membranes and eventually exert membrane perturbation-related antibiotic effects on target microbial cells

Folding propensity and biological activity of peptides: New insights from conformational properties of a novel peptide derived from Vitreoscilla haemoglobin.

The synthetic peptide Vitr-p-13 (YPIVGQELLGAIK-NH2), derived from the bacterial dimeric Vitreoscilla haemoglobin (VHb) in the position 95–107, is characterized by a preeminent ‘‘statistical coil’’ conformation in water as demonstrated by CD experiments and long time-scaleMD simulations. In particular, Vitr-p-13 does not spontaneously adopt an alpha-helix folding in water, but it is rather preferentially found in beta-hairpin-like conformations. Long time-scale MD simulations have also shown that Vitrp- 13 displays a ‘‘topological-trigger’’ which initiates alphahelix folding within residues 7–10, exactly like seen in the temporins, a group of linear, membrane-active antimicrobial peptides of similar length. At variance with temporins, in Vitr-p-13 such a process is energetically very demanding (110 kJ/mol) in water at 300 K, and the peptide was found to be unable to bind model membranes in vitro and was devoid of antimicrobial activity. The present results, compared with previous studies on similar systems, strengthen the hypothesis of the requirement of a partial folding when still in aqueous environment to allow a peptide to interact with cell-membranes and eventually exert membrane perturbation-related antibiotic effects on target microbial cells