Alignment and Chirality in Gaseous Flows

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Double photoionization of propylene oxide: a coincidence study of the ejection of a pair of valence-shell electrons

Propylene oxide, a favorite target of experimental and theoretical studies of circular dichroism, was recently discovered in interstellar space, further amplifying the attention to its role in the current debate on protobiological homochirality. In the present work, a photoelectron-photoion-photoion coincidence technique, using an ion-imaging detector and tunable synchrotron radiation in the 18.0-37.0 eV energy range, permits us (i) to observe six double ionization fragmentation channels, their relative yields being accounted for about two-thirds by the couple (C2H4+, CH2O+) and one-fifth by (C2H3+, CH3O+); (ii) to measure thresholds for their openings as a function of photon energy; and (iii) to unravel a pronounced bimodality for a kinetic-energy-released distribution, fingerprint of competitive non-adiabatic mechanisms

A Drone-Based Application for Scouting Halyomorpha Halys Bugs in Orchards with Multifunctional Nets

In this work, we consider the problem of using a drone to collect information within orchards in order to scout insect pests, i.e., the stink bug Halyomorpha halys. An orchard can be modeled as an aisle-graph, which is a regular and constrained data structure formed by consecutive aisles where trees are arranged in a straight line. For monitoring the presence of bugs, a drone flies close to the trees and takes videos and/or pictures that will be analyzed offline. As the drone\u27s energy is limited, only a subset of locations in the orchard can be visited with a fully charged battery. Those places that are most likely to be infested should be selected to promptly detect the pest. We implemented the proposed approach on a DJI drone and evaluated its performance in the real-world environment

Focus on the Use of Resveratrol in Bladder Cancer

Bladder cancer is the most common tumor of the urinary system, with a high incidence in the male population. Surgery and intravesical instillations can eradicate it, although recurrences are very common, with possible progression. For this reason, adjuvant therapy should be considered in all patients. Resveratrol displays a biphasic dose response both in vitro and in vivo (intravesical application) with an antiproliferative effect at high concentrations and antiangiogenic action in vivo (intraperitoneal application) at a low concentration, suggesting a potential role for it in clinical management as an adjuvant to conventional therapy. In this review, we examine the standard therapeutical approach to bladder cancer and the preclinical studies that have investigated resveratrol in xenotransplantation models of bladder cancer. Molecular signals are also discussed, with a particular focus on the STAT3 pathway and angiogenic growth factor modulation

Orientation of Chiral Molecules by External Electric Fields: Focus on Photodissociation Dynamics

Molecular orientation is a fundamental requirement to study and control photoinitiated reactions. Experimental setups that make use of hexapolar electric filters combined with slice-ion imaging detectors were employed in these last years to investigate the photodissociation dynamics of chiral molecules. The final goal is the on-the-fly discrimination of oriented enantiomers, revealed by the different angular distributions in photofragment ion-imaging, as predicted from vector correlation studies. Here, we review experiments of photodissociation of oriented chiral molecules, with the aim of presenting limits emerging from these investigations and perspectives toward the achievement of the ultimate objective

Models of Aged Magnesium\u2013Silicate\u2013Hydrate Cements Based on the Lizardite and Talc Crystals: A Periodic DFT-GIPAW Investigation

Classical MD simulations and periodic DFT-GIPAW calculations have been employed to investigate possible structural models of aged magnesium 12silicate 12hydrate (M 12S 12H) cements. Four models were built, two based, respectively, on the lizardite Mg3Si2O5(OH)4 and talc Mg3Si4O10(OH)2 crystals in which we have modified the Mg/Si ratio and distribution of Qn silicon species (n is the number of bridging oxygens for each quaternary silicon atom) according to previous experimental evidence. The other two models were still based on the lizardite and talc crystals, but the original Mg/Si ratios were retained. The latter two models were used to simulate MSH binders containing different proportions of talc- and lizardite-based amorphous phases as proposed in several experimental works. From these initial models, additional structures were generated by adding increasing amounts of water molecules to investigate its effect on the structure and on the 29Si and 25Mg MAS NMR spectra. Our results demonstrate that MSH phases with an Mg/Si ratio close to 1 can be described as a defective talc-based model or as the combination of talc and lizardite amorphous models with the former being the dominant phase. In both cases, the hydrated models provide the best agreement with NMR experiments

Potential Energy Surfaces for Noble Gas (Ar, Kr, Xe, Rn)–Propylene Oxide Systems: Analytical Formulation and Binding

Multidimensional potential energy surfaces for heavy noble gas–propylene oxide systems are obtained by applying the phenomenological method successfully used to describe homologous systems involving He and Ne atoms. Such potential energy surfaces, where the interaction exclusively arises from the anisotropic van der Waals interaction components, are given in an analytical form. Therefore, they can be easily used as force fields to carry out molecular simulations to evaluate spectroscopic features and the dynamical selectivity of weakly bound complexes formed by propylene oxide (a prototype chiral species) with a noble gas atom (a prototype isotropic partner) by two-body collisions under a variety of conditions. Several potential energy minima are identified on the surfaces, which are confirmed and characterized by high level ab initio calculations. The next step to further generalize this methodology is its extension to systems involving propylene oxide-diatomic molecules (as H2, O2 and N2), as well as to propylene oxide dimers