Isomerism and decoherence

In the present paper we address the problem of optical isomerism embodied in the socalled “Hund’s paradox”, which points to the difficulty to account for chirality by means of quantum mechanics. In particular, we explain the answer to the problem proposed by the theory of decoherence. The purpose of this article is to challenge this answer on the basis of a conceptual analysis of the phenomenon of decoherence, that reveals the limitations of the theory of decoherence to solve the difficulties posed by optical isomerism and, in general, by quantum measurement.     

Easy Chemo-Enzymatic Synthesis of Human Milk Trisaccharides from a Common Selectively Protected Lactose Building Block

ABSTRACT

Three glycosyllactosides, contained in the neutral fraction of human milk oligosaccharides, were synthesised in a simple and straightforward manner through a sequence based on a chemo-enzymatic approach. Lipase catalysed regioselective 6'-O-acylation of benzyl β-lactoside, followed by the introduction of an isopropylidene group and acetylation afforded, depending on the reaction conditions, compounds 4a and 4b, which allow selective access to positions 3, 3' and 6'. Glycosylation with proper donors gave trisaccharides 6, 9 and 12.     

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.     

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.     

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.