Biological Activities Evaluation of Enantiopure Isoxazolidine Derivatives: In Vitro,In Vivo and In Silico Studies

Applied Biochemistry and Biotechnology - A series of enantiopure isoxazolidines (3a–c) were synthesized by 1,3-dipolar cycloaddition between a (−)-menthone-derived nitrone and various...     

AES, EELS and TRIM investigation of InSb and InP compounds subjected to Ar ions bombardment

The interaction of ions with matter plays an important role in the treatment of material surfaces. In this paper we study the effect of argon ion bombardment on the InSb surface in comparison with the InP one. The Ar⁺ ions, accelerated at low energy (300 eV) lead to compositional and structural changes in InP and InSb compounds. The InP surface is more sensitive to Ar⁺ ions than that of InSb. These results are directly inferred from the qualitative Auger electron spectra (AES) and electron energy loss spectroscopy (EELS) analysis. However, these techniques alone do not allow us to determine with accuracy the disturbed depth in Ar⁺ ions of InP and InSb compounds. For this reason, we combine AES and EELS with the simulation method TRIM (transport and range of ions in matter) to show the mechanism of interaction between the ions and the InP or InSb and hence determine the disturbed depth as a function of Ar⁺ energy.     

Investigation by EELS and TRIM simulation method of the interaction of Ar and N ions with the InP compound

In this study, the EELS results revealed the great sensitivity of InP compound submitted to Ar⁺ or N⁺ ions at low energy. The preliminary treatment of InP by the Ar⁺ ions was useful as part of the cleaning process of the surface. Further argon ions bombardment on cleaned InP led however to breaking of chemical bonds In–P, with desorption of phosphorus atoms and appearance of In metal distributed on InP. The damaged InP by Ar⁺ ions, constituted the diphase (In; InP) system of depth of about 30 Å, involving a superficial roughness. The In metal proportion on such a system was determined by a calculation method based on the experimental EELS spectra of pure In and InP.We submitted the heated and no heated system (In; InP) to nitrogen ions bombardment. The nitrogen reacted with the In metal to compensate the phosphorus vacancies so that InN species were formed. The heating of (In; InP) system at 450 °C, allowed the surface reconstruction with elimination of defects due to the structure and the roughness. The temperature also caused the coalescence of In metal towards the surface. Because of the physical stability of the interface of heated (In; InP) system, the nitrogen reacted with the outmost layers of In metal to form a homogeneous layer of InN of thickness estimated at 20 Å. We associated to the EELS the TRIM (Transport and Range of Ions in Matter) simulation method in order to show the mechanism of interaction Ar⁺ or N⁺ ions-InP and determine the disturbed depth as a function of the energy. The EELS alone was not able to give us with accuracy the disturbed depth of the target by these ions.     

Electronic transitions in α, θ and γ polymorphs of ultraporous monolithic alumina

Spectroscopy of α, θ, and γ phases of high‐purity ultraporous alumina has been studied at cryogenic temperatures of 7 K in the near‐IR–VUV range of spectra with synchrotron radiation excitation. The UV photoluminescence (PL) spectra are dominated by optical transitions of self‐trapped excitons, while the PL excitation spectra are assigned to free excitons and interband transitions. The analysis of PL excitation spectra indicates a tendency to fundamental bandgap narrowing in order of 9.36 eV (α) to 7.60 eV (θ) and 6.85 eV (γ). Structural defects related to oxygen vacancies are responsible for the visible F⁺/F transitions decrease in order γ > θ > α. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Theoretical study of species formed by IA and IB metals or ions and a CN ligand

Multireference second-order perturbation calculations have been carried out for copper and sodium complexes involving one CN ligand. Neutral compounds are strongly linked, cyanides M-CN being more stable than isocyanides M-NC (M = Cu, Na) as in the case of the pair HCN/HNC. Cations are much less strongly linked, Cu-NC⁻ being predicted to be the only system having a fairly bound structure, at variance with the dominance of the cyanide form in the HCN⁺/HNC⁺ pair.     

Association of metal cations with alkanes: Na(CH4)+ versus Cu(CH4)+ as molecular models

Summary Ab initio molecular orbital calculations give small stabilization energies for the various Na(CH₄)⁺ adducts (less than 4 kcal mol^–1), but predict a stronger binding for the copper compounds (about 13 kcal mol^–1). The different behaviour of Na⁺ and Cu⁺, already present at the SCF level, is reinforced by electron correlation. This can be attributed to an important contribution of the dispersion energy to the binding energy of the copper ion: about 40% of the total, including basis set superposition corrections.Dedicated to Mrs A. Pullman     

Study by EELS and EPES of the stability of InPO4/InP system

The goal of this research is to highlight the effectiveness of associating the spectroscopic methods EELS and EPES in the study of thin film grown on substrates. We use the great sensitivity of the Electron Energy Loss Spectroscopy (EELS) and the Elastic Peak Electron Spectroscopy (EPES) to study native InPO₄ oxide of thin thickness (10 Å) grown on InP by UV/ozone oxidation. By varying the primary energy of the electron beam and the incidence angle, we give interesting results related to the chemical and the physical analyses of InPO₄/InP system. These spectroscopic methods reveal the homogeneity of the chemical composition of InPO₄ on the surface. Furthermore, the electron irradiation of InPO₄/InP leads to the breaking of chemical bonds between the species of InPO₄ and InP to form a new oxide In₂O₃ on the surface. We show that the heating of InPO₄/InP at 450 °C in UHV allows a good reconstruction of the surface with elimination of defects on the surface and at the interface. Thus, the surface becomes more stable to impede all oxidation processes due to the electron beam irradiation even for a time as long as 30 min.