The Direction of Time: From the Global Arrow to the Local Arrow

In this paper we discuss the traditional approaches to the problem of the arrow of time. On the basis of this discussion we adopt a global and nonentropic approach, according to which the arrow of time has a global origin and is an intrinsic, geometrical feature of space-time. Finally, we show how the global arrow is translated into local terms as a local time-asymmetric flux of energy.     

Modal-Hamiltonian Interpretation of Quantum Mechanics and Casimir Operators: The Road Toward Quantum Field Theory

The general aim of this paper is to extend the Modal-Hamiltonian interpretation of quantum mechanics to the case of relativistic quantum mechanics with gauge U(1) fields. In this case we propose that the actual-valued observables are the Casimir operators of the Poincaré group and of the group U(1) of the internal symmetry of the theory. Moreover, we also show that the magnitudes that acquire actual values in the relativistic and in the non-relativistic cases are correctly related through the adequate limit.     

A Rapid,Highly Sensitive and Selective Phosgene Sensor Based on 5,6-Pinenepyridine

The toxicity of phosgene (COCl₂) combined with its extensive use as a reactant and building block in the chemical industry make its fast and accurate detection a prerequisite. We have developed a carboxylic derivative of 5,6-pinenepyridine which is able to act as colorimetric and fluorimetric sensor for phosgene in air and solution. For the first time, the formation of a pyrido-[2,1-a]isoindolone was used for this purpose. In solution, the sensing reaction is extremely fast (under 5 s), selective and highly sensitive, with a limit of detection (LOD) of 9.7 nM/0.8 ppb. When fixed on a solid support, the sensor is able to detect the presence of gaseous phosgene down to concentrations of 0.1 ppm, one of the lowest values reported to date.     

Pomegranate By-Products as Natural Preservative to Prolong the Shelf Life of Breaded Cod Stick

This work evaluated the efficacy of pomegranate byproducts, specifically peel powder, as valid preservatives for food quality. Ready-to-cook cod sticks breaded with pomegranate peel powder were prepared. Shelf-life tests were conducted on breaded cod sticks during refrigerated storage (17 days) at 4 °C, monitoring the pH, microbiological and sensory quality. In addition, the nutritional quality of both the breaded and control samples was assessed. The results highlighted that active samples showed higher phenol and flavonoid content and higher antioxidant activity compared to the control fish, suggesting that pomegranate peel powder was responsible for a significant increase in cod stick nutritional quality. Furthermore, the cod stick active breading led to a delay in microbial growth without affecting the sensory properties; rather, it helped slow down the sensory attribute decline during the refrigerated storage. The data suggest that using pomegranate byproducts in breaded cod stick was effective in prolonging its shelf life, as well as improving its nutritional quality. Therefore, pomegranate peel powder can be considered as a potential resource as natural food preservative.     

Luminescence-detected phase transitions in lanthanide-containing liquid crystals

Complexes between lanthanide nitrates and a pro-mesogenic 18-membered diaza-substituted coronand are luminescent both as powders and liquid crystals (between 87 and 195 degrees C), and the phase transitions are detected by monitoring luminescence intensity and lifetime.     

Infrared and raman spectra,vibrational assignments,normal coordinate analysis,and ab initio calculations of methyltrifluoromethyldisulfide and bis(trifluoromethyl)disulfide

The infrared and Raman (3500-35 cm^–1) spectra of gaseous and solid methyltrifluoromethyldisulfide, CF₃SSCH₃, and bis(trifluoromethyl)disulfide, CF₃SSCF₃, have been recorded. Additionally, the Raman spectra of the neat liquids have been obtained and qualitative depolarization values have been measured. These vibrational data have been interpreted, for both molecules, on the basis that the C-S-S-C dihedral angle is approximately 90°. Vibrational assignments are given for both molecules and are supported by normal coordinate calculations utilizing ab initio Hartree-Fock gradient calculations with the 3-21G^* basis set to obtain the frequencies for the normal modes and potential energy distributions. The CH₃ and CF₃ torsional modes have been observed at 140 and 48 cm^–1, respectively, for CF₃SSCH₃, from which periodic barriers of 485 cm^–1 (1.39 kcal mol^–1) and 853 cm^–1 (2.44 kcal mol^–1), respectively, have been calculated. Complete equilibrium geometries have been determined for both molecules by ab initio calculations employing both 3–21G and 6–31G basis sets. The structural parameters for bis(trifluoromethyl)disulfide are compared to those suggested from electron diffraction studies. The results are compared to corresponding quantities obtained for some similar molecules.Taken in part from the thesis of M. M. Bergana which will be submitted to the Department of Chemistry in partial fulfillment of the Ph.D. degree.     

Prigogine and the many voices of nature

Ilya Prigogine was not a systematic author: his ideas, covering a wide arch of areas, are dispersed in his many writings. In particular, his philosophical thought has to be reconstructed mainly on the basis of his works in collaboration with Isabelle Stengers: La Nouvelle Alliance (1979), Order out of Chaos (1984), and Entre le Temps et l’éternité (1988). In this paper I undertake that reconstruction in order to argue that Prigogine’s position, when read in the light of Putnam’s internalist realism, can be characterized as an ontological pluralism. The main aim of this work is to show the striking parallelism between the philosophical views of Prigogine and Stengers and those of Hilary Putnam in Reason, Truth and History (1981). This task will lead me to critically review Prigogine’s general scientific program: the attempt to establish the foundations of objective irreversibility.     

Enantiopure, supramolecular helices containing three-dimensional tetranuclear lanthanide(III) arrays: synthesis, structure, properties, and solvent-driven trinuclear/tetranuclear interconversion

The enantiomerically pure pinene-bipyridine-based receptor, (-) or (+) L(-), diastereoselectively self-assembles in dry acetonitrile in the presence of Ln(III) ions (Ln = La, Pr, Nd, Sm, Eu, Gd, and Tb) to give a C3-symmetrical, pyramidal architecture with the general formula [Ln4(L)9(mu3-OH)](ClO4)2) (abbreviated as tetra-Ln4L9). Three metal centers shape the base: an equilateral triangle surrounded by two sets of helically wrapping ligands with opposite configurations. This part of the structure is very similar to the species [Ln3(L)6(mu3-OH)(H2O)3](ClO4)2) (recently reported by us and abbreviated as tris-LnL2) formed by the ligand and the Ln(III) ions when the reactions are performed in methanol. The tetranuclear structure is completed by a capping, helical unit LnL3 whose chirality is also predetermined by the chirality of the ligand. A complete characterization of these isostructural, chiral compounds was performed in solid state (X-ray, IR) and in solution (ES-MS, NMR, CD, UV-vis and emission spectroscopies). The sign and the intensity of the CD bands in the region of the pi pi* transitions of the bipyridine (absolute Delta epsilon values at 327 nm are about 280 M(-1) x cm(-1)) are highly influenced by the helicity of the capping fragment LnL3. The photophysical properties (lifetime, quantum yield) of the visible (Eu and Tb complexes) and NIR (Nd complex) emitters indicate a good energy transfer between the ligands and the metal centers. The two related superstructures tetra-Ln4L9 and tris-LnL2 can be interconverted in acetonitrile, the switching process depending on the amount of water present in the solvent, the size of the Ln(III) ion, and the concentration. The weak chiral recognition capabilities of the self-assembly leading to the formation of tetra-Ln4L9 either by direct synthesis from a racemic mixture of the ligand and Ln(III) ions or by the conversion of a tris-Ln[(+/-)-L]2 racemate were likewise demonstrated.