Graded Betti numbers of some embedded rationaln-folds

Supported, in part, by the Natural Sciences and Engineering Research Council of Canada     

Computational approaches to shed light on molecular mechanisms in biological processes

Computational approaches based on Molecular Dynamics simulations, Quantum Mechanical methods and 3D Quantitative Structure-Activity Relationships were employed by computational chemistry groups at the University of Milano-Bicocca to study biological processes at the molecular level. The paper reports the methodologies adopted and the results obtained on Aryl hydrocarbon Receptor and homologous PAS proteins mechanisms, the properties of prion protein peptides, the reaction pathway of hydrogenase and peroxidase enzymes and the defibrillogenic activity of tetracyclines.     

Yttrium Geothermometry Applied to Garnets from Different Metamorphic Grades Analysed by EPMA and µ-PIXE Techniques

We present a multi-analytical and multi-instrumental approach to a petrologic study of garnets from metapelites characterized by different metamorphic grades. The comparison between major, minor and trace element (Y) distribution in garnets crystallized at different temperatures was performed by electron microprobe (EDS and WDS) and the Proton Induced X-ray Emission microprobe (μ-PIXE). Two garnet samples were selected from metapelite rocks at different metamorphic grades from the tectonic unit of Stilo, Calabrian–Peloritanian Arc, Southern Italy. Quantitative spot analysis profiles and compositional X-ray maps of major elements and yttrium are reported. The major element zoning of garnets is mostly characterized by a smoothed and gradual concentric variation of all elements from core to rim. The Y concentration reveals a marked zoning with its distribution decreasing from about 7000 ppm to about 100 ppm from core to rim, respectively. The precise determination of the Y content by μ-PIXE technique allowed us to better define the rock thermal history, by applying the Y geothermometer. In particular, a common starting temperature of about 450 °C was calculated for the beginning of the garnet growth from all over the unit, but different temperatures in the range from 520 °C to 670 °C were estimated for the peak event in garnets from different areas, in agreement with the P–T values given by the main rock mineral assemblages, reflecting a different metamorphic grade.     

Optical fiber sensor for oxygen detection working on an absorption basis

Painstaking spectrophotometric investigation was carried out on organo-metallic compounds to identify the most suitable compound for the detection of oxygen. A bis (histidinato) cobalt(II) solution was chosen, characterized by an absorption change at λ-408 nm as a function of the molecular oxygen concentration in the surrounding environment. An optical fiber system was developed that makes use of a halogen lamp as the source and an appropriate electronic circuit as a detection system. The optrode is a very small hollow fiber membrane filled with the solution and coupled with optical fibers.     

On almost periodic orbits and minimal sets

In this short note we solve in the negative the three problems recently posed by Jie-Hua Mai and Wei-Hua Sun regarding the behaviour of almost periodic orbits and minimal sets of dynamical systems whose phase space is not regular.     

Rearrangement of N-Aryl-2-Vinylaziridines to Benzoazepines and Dihydropyrroles: A Synthetic and Theoretical Study

Herein we report the one-pot synthesis of several N-heterocyclic compounds by rearrangement reactions of N-aryl-2-vinylaziridines. The optimization of the synthetic methodology employed allowed us to obtain differently substituted 2,5-dihydro-1H-benzo[b]azepines in good yields and purities. The relationship between the nature of the starting N-aryl-2-vinylaziridine and the obtained N-heterocycle was also investigated. Finally, to rationalize all the experimental results reported in this paper a theoretical study was performed that casts light on the reaction mechanism.     

A molecular modelling approach to rationalize the stereochemical outcome of the Burkholderia cepacia lipase-catalyzed transesterification of aromatic primary alcohols with vinyl esters with different chain lengths in chloroform

The Burkholderia cepacia lipase-catalyzed transesterification of 2-methyl-3-phenyl-1-propanol with vinyl esters proceeds with high enantioselectivity independently of the acyl chain length and the low enantioselectivity of the same reaction with 2-phenyl-1-propanol is not affected by chain length of the vinyl esters. A molecular modelling approach has been developed in order to rationalize the enzymatic results.     

Enantioselective synthesis,chiroptical properties and absolute configuration of 3-aminosubstituted isothiazole S-oxides

Herein we report a mild and efficient method to synthesize chiral 3-aminosubstituted isothiazole sulfoxides taking advantage of (+)- and (?)-((8,8-dichlorocamphoryl)sulfonyl)oxaziridine under microwave irradiation. The determination of the absolute configuration of the chiral sulfoxide was achieved by theoretical calculation of the CD spectra. The reason for the observed stereoselectivity was enlightened by means of analysis of our data using DFT calculations.