A. Poletti

Use of thermodynamic indices as ecological indicators of the development state of lake ecosystems: 2. Exergy and specific exergy indices

Abstract The effectiveness of exergy and specific exergy indices as ecological indicators of the trophic state of lake ecosystems is here tested on a small homogeneous set of shallow lakes which, in spite of their similar nutrient concentrations, morphology and hydrology, show a different trophic state and structure, species composition and abundance. The findings reveal that exergy and specific exergy indices have good negative correlation with phytoplankton biomass and Carlsons trophic state index (TSI) and strong positive correlation to water transparency (the relationship between exergy and eutrophication is clearer if the exergy refers to surface units, rather than volume units) and, hence, that they may be used as ecological indicators of the trophic state of lake ecosystems. The relationship between the responses of the thermodynamic approach and other conventional trophic classification methods (Vollenweiders eutrophication model based on phosphorus loading, the Hillbrich-Ilkowska method and the Vollenweider–OECD classification criterion) previously applied to Lake Trasimeno, was also investigated. The decreasing trend of exergy and specific exergy indices with eutrophication increase appears to be essentially due to the change in species composition and trophic structure, rather than to a different trophic potentiality of the ecosystems investigated. Concerning the identification of the environmental factors responsible for exergy and specific exergy trends, the coherence of the correlation structure between water depth, TSI, exergy and specific exergy indices, suggests that the lakes mean water depth plays a significant role in determining the changes in trophic structure and state (and consequently in exergetic indices) within the set of lakes examined and emphasises the importance of lake morphology in the development and ageing of lake ecosystems.

Use of thermodynamic indices as ecological indicators of the development state of lake ecosystems. 1. Entropy production indices

Abstract The effectiveness of Aokis entropy production indices as ecological indicators of the trophic state is tested here under the changing hydrological conditions of Lake Trasimeno, a shallow freshwater lake in Italy. The analysis leads to a review of Aokis indices and a definition of a new set of eutrophication indices ( c , d , d ′) based on the entropy production per surface unit rather than volume unit, which seem to be good ecological indicators for the trophic state of lake ecosystems. The positive correlation between these indices and the trophic state of a small set of lakes suggests that they are able to take into account the influence of the biological productivity on the whole entropy production of the systems. Moreover, the indices d and d ′ show a good negative linear correlation to the lake mean depth, showing the importance of this morphological parameter in the eutrophication process or succession in lakes. The values of the indices show that Lake Trasimeno exhibits a trophic state consistent with Carlsons TSI indices and with the results previously obtained by the application of Vollenweiders eutrophication model based on phosphorus loading and the Hillbrich–Ilkowska method, but less compliant with the Vollenweider–OECD classification criterion. The study emphasises the importance of a holistic thermodynamic approach in getting new insight into the fundamental mechanisms of the ecological succession of lake ecosystems.

Vibrational spectrum of sodium nitroprusside. Normal coordinateanalysis for the Fe(CN)5NO2− ion

Abstract The analysis of the infrared and Raman spectra of Na 2 [Fe(CN) 5 NO] · 2H 2 O has led to an assignment of the fundamental vibrations of the Fe(CN) 5 NO 2− ion which is supported by studies of the infrared spectra of Na 2 [Fe(CN) 5 15 NO] · 2H 2 O, Na 2 [Fe(CN) 5 NO] · 2(H,D) 2 O and Na 2 [Fe(CN) 5 NO]. A normal coordinate treatment (using a diagonal symmetry force field) has been carried out on the basis of a C 4v symmetry model for the anion. The significance of the resulting valence force constants is briefly discussed.

Infrared crystal spectra of heterocyclic compounds. 1 . IR spectra of solid modifications of thiophene

Abstract The infrared spectra of the four solid modifications of thiophene have been studied. Absence of appreciable band shifts and solid state splitting, in going from the liquid to the solid phases, seems to indicate that the crystals of thiophene are disordered at least until the 4th solid modification becomes stable. Polarization measurements, carried out on the 4th phase, allow a tentative determination of the crystal structure at 100°K.

Low-frequency infrared spectra of π-arenechromiumtricarbonyl complexes and normal coordinates of C6H6Cr(CO)3

Abstract Infrared spectra in the range 700–250 cmP −1 have been studied for several π-arenechromiumtricarbonyl complexes (arene = benzene, chlorobenzene, methyl benzoate, anisole, mesitylene, aniline, N-dimethylaniline, o - and p -toluidine). Comparison with the ligand spectra enabled the ligand frequencies to be localized and the A 1 and E Cr-C-O bending and Cr-C stretching modes were reassigned on the basis of a C 3V local symmetry for the -Cr(CO) 3 groupings. A normal coordinate treatment has been carried out on C 6 H 6 -Cr(CO) 3 , in a point-ring approximation, using a diagonal symmetry force field.

Vibrational analysis of tellurophene and its deuterated derivatives

Abstract The i.r. and Raman spectra of tellurophene, tellurophene-2- d 1 , tellurophene-2-5- d 2 , tellurophene-3-4- d 2 , tellurophene-2-3-4- d 3 and tellurophene-2-3-4-5- d 4 have been studied. A vibrational assignment of the fundamental frequencies of all these molecules has been carried out on the basis of i.r. vapor band contours and depolarization states of Raman lines. Such an assignment conveniently fits the isotopic “sum” and “product” rules. A comparison of the vibrational behaviour of tellurophene and that of the other congeners is made and a rationalization of some frequency shifts is attempted.

Vibrational spectra of π-allyl-and π-allyl-d5-dicarbonyl-nitrosyliron

Abstract Vibrational spectra of π-C3H5Fe(CO)2NO and π-C3D5Fe(CO)2NO have been studied in the liquid and solid states. The spectra have been interpreted on the basis of a C3 molecular symmetry. A reassignment of some bands is proposed for the allylic fragment based on vH/vD isotopic shifts. Examination of spectra of deuteriated derivatives has also allowed a reasonable assignment of all modes involving the FeCO and FeNO groups.

Infrared crystal spectra of heterocyclic compounds. II. IR spectrum of selenophene in the solid state

Abstract Infrared spectra of solid selenophene at different temperatures, have been measured using polarized radiation. Just below the freezing point the selenophene molecule has a noticeable degree of ring-rigidity, allowing for a definite location in sites of lower symmetry than the molecular one. Dichroic behaviour of IR lines in the solid state enables us to attribute the bands to the relative symmetry species and give a tentative hypothesis for the space group of the crystalline selenophene.

Photophysical and Photosensitizing Properties of Photofrin II

Photofrin II is a newly developed Hematoporphyrin Derivative (Oncology Research & Development), which is widely used in the. phototherapy of tumors owing to its optimal tumor-localizing properties and ability to photosensitize the killing of the tumor cells upon visible light-irradiation1. As known, the mechanism and efficiency of porphyrin photosensitization is dependent on several parameters, including the chemical structure of the porphyrin, its aggregation state and the nature of the micro environment2–5. Therefore, we decided to perform a detailed investigation on the photo-physical and photosensitizing properties of Photofrin II, using experimental conditions which mimic specific situations occurring in vivo.

Laser photolysis study of the hematoporphyrin IX—ℓ-tryptophan system in solvent mixtures at different polarity

Abstract The oxygen and l-tryptophan (TRP) effect on the triplet state of hematoporphyrin IX (HP) has been investigated by means of the laser photolysis technique at room temperature, in various pH 7.4 buffered aqueous/formamide or methanol mixtures with different polarity. The quenching of the HP triplet state by oxysgen is not affected by the medium polarity (kq O2 = 1.5 × 109 M−1 s−1), whereas the quenching by TRP appears dependent on the composition. The mechanism of the HP-sensitized photooxidation of TRP is discussed.