Acceleration of decomposition of CL-20 explosive under nanoconfinement

Journal of Thermal Analysis and Calorimetry - The thermal properties of CL-20 explosive in the bulk and confined in controlled pore glass matrices to nanoscale dimensions were studied using dynamic...     

Thiophene based europium β-diketonate complexes: effect of the ligand structure on the emission quantum yield

The synthesis and the molecular and photophysical characterization, together with solid state and solution structure analysis, of a series of europium complexes based on β-diketonate ligands are reported. The Eu(III) complex emission, specifically its photoluminescence quantum yield (PL-QY), can be tuned by changing ligands which finely modifies the environment of the metal ion. Steady-state and time-resolved emission spectroscopy and overall PL-QY measurements are reported and related to geometrical features observed in crystal structures of some selected compounds. Moreover, paramagnetic NMR, based on the analogous complexes with other lanthanides, are use to demonstrate that there is a significant structural reorganization upon dissolution, which justifies the observed differences in the emission properties between solid and solution states. The energy of the triplet levels of the ligands and the occurrence of nonradiative deactivation processes clearly account for the luminescence efficiencies of the complexes in the series.     

Stereoselective synthesis of novel C-3 functionalized 3-sulfonyl-β-lactams: Promising biologically active heterocyclic scaffolds

An efficient and operationally simple strategy for the stereoselective synthesis of novel C-3 functionalized 3-sulfonyl-β-lactam heterocycles is described. The C-3 functionalized 3-phenyl/benzylsulfonyl-β-lactams 3/3′, 5/5′ has been synthesized via Michael addition using different Michael acceptors on trans-3-phenyl/benzylsulfonyl-β-lactams 2(a–f) using K₂CO₃ as a base and acetonitrile/DMF as solvents. The reaction furnished exclusively cis-β-lactam adducts 3(a–r) using sterically less hindered Michael acceptors. Further, the effect of steric bulk and chiralilty of Michael acceptors was explored to achieve target C-3 functionalized β-lactams 3(s-u)/3′(s-u) and 5(a–c)/5′(a–c). The structural and stereochemical analysis of novel β-lactams were carried out using FT-IR, NMR (¹H, ¹³C, ¹H-¹H COSY, ¹H-¹³C COSY and ¹³C DEPT-135), elemental analysis (CHNS), mass spectrometry (EIMS and LCMS) in representative cases and single crystal X-ray crystallographic studies (3e). The cis or trans configuration of the Michael acceptor (E) at C-3 was assigned with respect to C4-H.     

An Optimal Chance Constraint Multivariate Stratified Sampling Design Using Auxiliary Information

When we are dealing with multivariate problem then we need an allocation which is optimal for all the characteristics in some sense because the individual optimum allocations usually differ widely unless the characteristics are highly correlated. So an allocation called “Compromise allocation” is to be worked out suggested by Cochran. When auxiliary information is also available, it is customary to use it to increase the precision of the estimates. Moreover, for practical implementation of an allocation, we need integer values of the sample sizes. In the present paper the problem is to determine the integer optimum compromise allocation when the population means of various characteristics are of interest and auxiliary information is available for the separate and combined ratio and regression estimates. This paper considers the optimum compromise allocation in multivariate stratified sampling with non-linear objective function and probabilistic non-linear cost constraint. The probabilistic non-linear cost constraint is converted into equivalent deterministic one by using Chance Constrained programming. The formulated multi-objective nonlinear programming problem is solved by Fuzzy Goal programming approach and Chebyshev approximation. Numerical illustration is also given to show the practical utility of the approaches.     

An inverse hyper-spherical harmonics-based formulation for reconstructing 3D volumetric lung deformations

A method to estimate the deformation operator for the 3D volumetric lung dynamics of human subjects is described in this paper. For known values of air flow and volumetric displacement, the deformation operator and subsequently the elastic properties of the lung are estimated in terms of a Green's function. A Hyper-Spherical Harmonic (HSH) transformation is employed to compute the deformation operator. The hyper-spherical coordinate transformation method discussed in this paper facilitates accounting for the heterogeneity of the deformation operator using a finite number of frequency coefficients. Spirometry measurements are used to provide values for the airflow inside the lung. Using a 3D optical flow-based method, the 3D volumetric displacement of the left and right lungs, which represents the local anatomy and deformation of a human subject, was estimated from 4D-CT dataset. Results from an implementation of the method show the estimation of the deformation operator for the left and right lungs of a human subject with non-small cell lung cancer. Validation of the proposed method shows that we can estimate the Young's modulus of each voxel within a 2% error level.     

A convenient synthesis of azetidine-2,3-diones (α-Keto-β-Lactams)

Azetidine-2,3-diones can be conveniently synthesized by mild hydrolysis of the product of the reaction between α-phenylthio-β-lactams and sulfuryl chloride.     

A local notion of absolute continuity in ℝ n

We consider the notion ofp, δ-absolute continuity for functions of several variables introduced in [2] and we investigate the validity of some basic properties that are shared by absolutely continuous functions in the sense of Maly. We introduce the classδ−BV _loc ^p (Ω, ℝ ^m ) and we give a characterization of the functions belonging to this class. Supported by MURST of Italy.     

Application of electronic circular dichroism in configurational and conformational analysis of organic compounds

This tutorial review is addressed to readers with a background in basic organic chemistry and spectroscopy, but without a specific knowledge of electronic circular dichroism. It describes the fundamental principles, instrumentation, data analysis, and different approaches for interpretation of ECD. The discussion focuses on the application of ECD, also in combination with other methods, in structural analysis of organic compounds, including host-guest complexes, and will emphasize the importance of the interplay between configurational and conformational factors. The tutorial also covers modern supramolecular aspects of ECD and recent developments in computational methods.     

A new, stereoselective, ring-forming reaction of 1,2-ethanedithiol with N-acylated indoles

While attempting to prepare 2,5-dithiacyclopentyl derivatives from N-acyl 5-fluoroindole by reaction with 1,2-ethanedithiol we discovered that, instead of the expected product, annelation occurred to give a tricyclic compound containing a 3,6-dithiaazepine ring. This reaction is stereoselective and was found to be general for N-acylindoles, not being affected by substituents on the indole ring.