Molecular Conformation of Pyridinic Aromatic Esters. II. Electronic Absorption Spectra and Dipole Moments by Semiempirical Methods

The semiempirical MIM method was applied to calculate the UV spectra of nine pyridine-aromatic-ester derivatives (having the general formula R1-COO-R2) assuming a planar geometry. Benzene, pyridine and formic acid were adopted as component systems. The dipole moments of the same compounds were evaluated at the MIM and INDO levels and the equilibrium percentage of the conformers was deduced from experimental and theoretical values. Comparable results were generally obtained. On the whole the results are satisfactory but not sufficient to affirm with certainty if the molecular skeleton is or is not planar

Molecular Conformation of Aza-substituted Benzanilides by Electronic Absorption Spectra and Dipole Moments

The electronic absorption spectra of thirteen pyridine aromatic amides of general formula R1-CO-NH- R2 (Ri, R2 = pyridil or phenyl) were obtained in methanol and dioxane solution. The band assignment is briefly discussed. The dipole moments were measured in dioxane at 25 ± 0.1 °c and compared with values calculated by both the S. H. M. 0. method and vectorial model. The comparison suggests the most probable conformation of derivatives which have the nitrogen either in the ortho or meta position in one or both rings of the molecule

A Two-Threshold Model for Scaling Laws of Non-Interacting Snow Avalanches

The sizes of snow slab failure that trigger snow avalanches are power-law distributed. Such a power-law probability distribution function has also been proposed to characterize different landslide types. In order to understand this scaling for gravity driven systems, we introduce a two-threshold 2-d cellular automaton, in which failure occurs irreversibly. Taking snow slab avalanches as a model system, we find that the sizes of the largest avalanches just preceeding the lattice system breakdown are power law distributed. By tuning the maximum value of the ratio of the two failure thresholds our model reproduces the range of power law exponents observed for land-, rock- or snow avalanches. We suggest this control parameter represents the material cohesion anisotropy.Comment: accepted PR

Extrafloral-nectar based partner manipulation in plant-ant relationship

Plant–ant interactions are generally considered as mutualisms, with both parties gaining benefits from the association. It has recently emerged that some of these mutualistic associations have, however, evolved towards other forms of relationships and, in particular, that plants may manipulate their partner ants to make reciprocation more beneficial, thereby stabilizing the mutualism. Focusing on plants bearing extrafloral nectaries, we review recent studies and address three key questions: (i) how can plants attract potential partners and maintain their services; (ii) are there compounds in extrafloral nectar that could mediate partner manipulation; and (iii) are ants susceptible to such compounds? After reviewing the current knowledge on plant–ant associations, we propose a possible scenario where plant-derived chemicals, such as secondary metabolites, known to have an impact on animal brain, could have evolved in plants to attract and manipulate ant behaviour. This new viewpoint would place plant–animal interaction in a different ecological context, opening new ecological and neurobiological perspectives of drug seeking and use

Role of the IL-23/IL-17 Pathway in Rheumatic Diseases: An Overview

Interleukin-23 (IL-23) is a pro-inflammatory cytokine composed of two subunits, IL-23A (p19) and IL-12/23B (p40), the latter shared with Interleukin-12 (IL-12). IL-23 is mainly produced by macrophages and dendritic cells, in response to exogenous or endogenous signals, and drives the differentiation and activation of T helper 17 (Th17) cells with subsequent production of IL-17A, IL-17F, IL-6, IL-22, and tumor necrosis factor \u3b1 (TNF-\u3b1). Although IL-23 plays a pivotal role in the protective immune response to bacterial and fungal infections, its dysregulation has been shown to exacerbate chronic immune-mediated inflammation. Well-established experimental data support the concept that IL-23/IL-17 axis activation contributes to the development of several inflammatory diseases, such as PsA, Psoriasis, Psoriatic Arthritis; AS, Ankylosing Spondylitis; IBD, Inflammatory Bowel Disease; RA, Rheumatoid Arthritis; SS, Sjogren Syndrome; MS, Multiple Sclerosis. As a result, emerging clinical studies have focused on the blockade of this pathogenic axis as a promising therapeutic target in several autoimmune disorders; nevertheless, a greater understanding of its contribution still requires further investigation. This review aims to elucidate the most recent studies and literature data on the pathogenetic role of IL-23 and Th17 cells in inflammatory rheumatic diseases

Radiative Neutrino Decay in Media

In this letter we introduce a new method to determine the radiative neutrino decay rate in the presence of a medium. Our approach is based on the generalisation of the optical theorem at finite temperature and density. Differently from previous works on this subject, our method allows to account for dispersive and dissipative electromagnetic properties of the medium. Some inconsistencies that are present in the literature are pointed-out and corrected here. We shortly discuss the relevance of our results for neutrino evolution in the early universe.Comment: 11 pages, 3 encapsulated figure