Excited-State Dynamics of [Ru(bpy)3]2+ Thin Films on Sensitized TiO2 and ZrO2

The excited state dynamics of Tris(2,2′-bipyridine)ruthenium(II) hexafluorophosphate, [Ru(bpy)₃(PF₆)₂], was investigated on the surface of bare and sensitized TiO₂ and ZrO₂ films. The organic dyes LEG4 and MKA253 were selected as sensitizers. A Stern–Volmer plot of LEG4-sensitized TiO₂ substrates with a spin-coated [Ru(bpy)₃(PF₆)₂] layer on top shows considerable quenching of the emission of the latter. Interestingly, time-resolved emission spectroscopy reveals the presence of a fast-decay time component (25±5 ns), which is absent when the anatase TiO₂ semiconductor is replaced by ZrO₂. It should be specified that the positive redox potential of the ruthenium complex prevents electron transfer from the [Ru(bpy)₃(PF₆)₂] ground state into the oxidized sensitizer. Therefore, we speculate that the fast-decay time component observed stems from excited-state electron transfer from [Ru(bpy)₃(PF₆)₂] to the oxidized sensitizer. Solid-state dye sensitized solar cells (ssDSSCs) employing MKA253 and LEG4 dyes, with [Ru(bpy)₃(PF₆)₂] as a hole-transporting material (HTM), exhibit 1.2 % and 1.1 % power conversion efficiency, respectively. This result illustrates the possibility of the hypothesized excited-state electron transfer.     

Effects of ionizing radiation on bio-active plant extracts useful for preventing oxidative damages

Humans are exposed to ionizing radiations in medical radiodiagnosis and radiotherapy that cause oxidative damages and degenerative diseases. Airplane pilots, and even more astronauts, are exposed to a variety of potentially harmful factors, including cosmic radiations. Among the phytochemicals, phenols are particularly efficient in countering the oxidative stress. In the present study, different extracts obtained from plant food, plant by-products and dietary supplements, have been compared for their antioxidant properties before and after irradiation of 140 cGy, a dose absorbed during a hypothetical stay of three years in the space. All the dry extracts, characterized in terms of vitamin C and phenolic content, remained chemically unaltered and maintained their antioxidant capability after irradiation. Our results suggest the potential use of these extracts as nutraceuticals to protect humans from oxidative damages, even when these extracts must be stored in an environment exposed to cosmic radiations as in a space station.     

Chemical investigations of male and female leaf extracts from Schinus molle L.

The pepper-tree Schinus molle is an evergreen ornamental plant with various and diversified list of medical uses. In this article we analysed the chemical composition of male and female leaves of this plant during the off-flowering and flowering seasons. The leaf extracts were obtained by using a sequential extraction with solvents of different polarities and the chemical composition was investigated by GC-MS. The results showed a total of twenty-three components, in which elemol is the most abundant constituent followed by bicyclogermacrene, γ-eudesmol, α-eudesmol, β-eudesmol and isocalamendiol. The petroleum ether and diethyl ether extracts from male and female flowering and off-flowering leaves consisted of sesquiterpene hydrocarbons as a major constituent followed by monoterpene hydrocarbons, while the acetone extracts showed a different composition. The obtained results show differences in the chemical composition between male and female and flowering and not flowering.     

Screening of thermoacidophilic autotrophic bacteria for covellite solubilization

In an attempt to obtain suitable bacterial isolates for bioleaching of copper from chalcopyrite and covellite, soil samples taken from areas of the metal industry were screened using an enrichment procedure specially run at acidic pH and thermophilic temperature range, to overcome the limitations of mesophiles employed for the purpose besides having economic and environmental advantages. Of a total of 47 isolates, the most promising 3 having resistance to copper toxicity were evolved by subjecting them to gradually increasing concentrations of CuSO₄ by acclimatization runs conducted on an environmental shaker for 125 d at 65°C. The isolates, JVCu-8, JVCu-10, and JVCu-12, exhibited significantly enhanced bioleaching and copper tolerance ability at pH 3.5 and 60–70°C. The total solubilization of copper recorded was 87, 89.4, and 91.2% by JVCu-8, JVCu-10, and JVCu-12, respectively, and these isolates exhibited tolerance to CuSO₄ concentrations of 6.9, 7.2, and 7.2%, respectively. The isolates morphologically resembled Thiobacillus and Sulfolobus.     

A new integrated statistical approach to the diagnostic use of two-dimensional maps

Two-dimensional (2-D) electrophoresis is a very useful technique for the analysis of proteins in biological tissues. The complexity of the 2-D maps obtained causes many difficulties in the comparison of different samples. A new method is proposed for comparing different 2-D maps, based on five steps: (i) the digitalisation of the image; (ii) the transformation of the digitalised map in a fuzzy entity, in order to consider the variability of the 2-D electrophoretic separation; (iii) the calculation of a similarity index for each pair of maps; (iv) the analysis by multidimensional scaling of the previously obtained similarity matrix; (v) the analysis by classification or cluster analysis techniques of the resulting map co-ordinates. The method adopted was first tested on some simulated samples in order to evaluate its sensitivity to small changes in the spots position and size. The optimal setting of the method parameters was also investigated. Finally, the method was successfully applied to a series of real samples corresponding to the electrophoretic bidimensional analysis of sera from normal and nicotine-treated rats. Multidimensional scaling allowed the separation of the two classes of samples without any misclassification.     

Simple and immune relations on countable structures

 Let 𝒜 be a computable structure and let R be a new relation on its domain. We establish a necessary and sufficient condition for the existence of a copy ℬ of 𝒜 in which the image of R (?R, resp.) is simple (immune, resp.) relative to ℬ. We also establish, under certain effectiveness conditions on 𝒜 and R, a necessary and sufficient condition for the existence of a computable copy ℬ of 𝒜 in which the image of R (?R, resp.) is simple (immune, resp.). Received: 4 February 2001 Published online: 5 November 2002 RID="*" ID="*" The first three authors gratefully acknowledge support of the NFS Binational Grant DMS-0075899. RID="*" ID="*" The first three authors gratefully acknowledge support of the NFS Binational Grant DMS-0075899. RID="*" ID="*" The first three authors gratefully acknowledge support of the NFS Binational Grant DMS-0075899.     

Trivial, strongly minimal theories are model complete after naming constants

We prove that if is any model of a trivial, strongly minimal theory, then the elementary diagram is a model complete -theory. We conclude that all countable models of a trivial, strongly minimal theory with at least one computable model are -decidable, and that the spectrum of computable models of any trivial, strongly minimal theory is .