Synthesis and antitumor evaluation of novel sulfonylcycloureas derived from nitrogen mustard

A new series of sulfonylcycloureas derivatives have been synthesized and evaluated in vitro for their antitumor activity against four cancer cell lines (A431, Jurkat, U266, and K562). These compounds were prepared by the condensation of several sulfonamides (2a–m) with ethyl bis(2-chloroethyl)carbamate (1a). The relative cytotoxicity of these new derivatives in comparison to chlorambucil is reported.     

Design of a new oligotriazole peptide nucleic acid analogue (oT-PNA)

We describe in this Letter the synthesis of an original thymine azido-heterotrimer generated by Click Chemistry. This trimer has been obtained from an azido-thymidine and a new chloroethyl-propargylated PNA monomer analogue, after two azidation/click-reaction cycles. Conformational preferences of a rotameric intermediate have also been studied     

Study of thermal aging effect on space charge in poly(methyl methacrylate)

Charges evolution in poly(methyl methacrylate) (PMMA) samples under thermal aging effect has been studied by means of two complementary techniques, thermal step method (TSM) and thermally stimulated depolarization current (TSDC). For the first method, measurements reveal that injected charges, whose quantity is found depending on the number of applied temperature cycles, remain close to the surface sample. TSDC measurements have been carried out for different temperatures ranging from 25 °C to 140 °C. Three distinguishable dipolar relaxations (β₁, β₂ and α) have been highlighted. In the same way, the presence of polarization and injected charges has been confirmed. In support of electric characterization, X-ray reflectometry has been used. The obtained results equally emphasized the thermal aging effect on the material.     

Heat treatment effects on dielectric and physico-chemical properties of an epoxy polymer

Infrared (IR) spectroscopy, dielectric spectroscopy (DS), and thermally stimulated depolarization current (TSDC) have been used to study heat treatment effects on an epoxy-based polymer. Variations in physico-chemical and dielectric properties were examined for annealing temperatures between 55 and 170 °C. IR results have shown that heating causes both chain scission and thermal oxidation of the polymer, increasing thus the amount of trapped charges. The complex dielectric permittivity and the dielectric modulus have been analyzed, by means of DS, to highlight and separate charge relaxation phenomena from conduction contributions. Results indicate structural rearrangements, leading to a decrease of dipolar relaxation frequency (from 16 to 13.5 kHz) and an increase of the relaxation strength (around 20%). TSDC measurements have shown a current peak shift towards higher temperatures, and a significant intensity decrease, which is proportional to the quantity of released charges.     

Design,synthesis, characterization and catechol oxidase activity of novel class of multi-tripodal pyrazole and triazole-based derivatives

Research on Chemical Intermediates - A class of novel multi-tripodal ligands has been prepared via condensation reaction between pyrazole or triazole moieties and...     

Determination of N and O‐atoms and N2 (A) Metastable Molecule Densities in the Afterglows of N2‐H2, Ar‐N2‐H2 and Ar‐N2‐O2 Microwave Discharges

Early afterglows of N₂‐H₂, Ar‐N₂‐H₂ and Ar‐N₂‐O₂ flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atoms and the N₂ (A) metastable molecule densities are determined by optical emission spectroscopy after calibration by NO titration for N and O‐atoms and measurements of NO and N₂ band intensities. If an uncertainty of 30% is estimated on N‐atomic density, an inaccuracy of one order of magnitude is obtained on the O and N₂ (A) densities. In N₂‐(0.05‐2.5%)H₂ and Ar‐(1‐50%)N₂‐(0.05‐2.5%) H₂ gas mixtures, the O‐atoms are coming from O₂ impurities in the discharge. Concentrations of N and O‐atoms and of N₂ (A) densities are compared to the ones obtained in Ar‐(5‐50%)N₂‐(0.2‐2.5%) O₂ gas mixtures in which a controlled amount of O₂ is added. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

High-spin states in189Hg

High-spin levels in¹⁸⁹Hg have been populated via the¹⁷⁵Lu(¹⁹F, 5n) reaction. A rotation-aligned band built on a 13/2⁺ state originating from theνi _13/2 subshell is identified which is interpreted within the framework of “quasiparticle+rotor” models. A negative parity band built on a 21/2^? state which can be accounted for by a three quasi-particle state is also observed.     

A simple and tailor‐made fabrication of porous silicon carbide from functionalized kraft pulp paper

Porous silicon carbide (SiC) materials were fabricated using the polymer‐derived ceramics method with kraft pulp papers (KPP) and a commercial polycarbosilane, the allylhydridopolycarbosilane (AHPCS), as starting materials. For this, KPP, propargylated KPP, or phosphorylated KPP were used to be impregnated by the AHPCS, with or without Karstedt catalyst. The pyrolysed materials were characterized at different stages, by using thermogravimetric analysis (TGA) coupled with mass spectrometry, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Depending on the nature of the initial template, various architectured SiC ceramics were successfully obtained with adjustable porosities. The key role of the previous functionalization of the papers was highlighted in terms of interactions at the interface between the polymer and the lignocellulosic handsheets. It led to either replica or sacrificial template methods. Thus, it was possible to tune the open porosity of the porous carbon and β‐SiC materials between 14.8% and 92.9%, with ceramic yields varying from 12% to 71%.     

One-pot and catalyst-free amidation of ester: a matter of non-bonding interactions

This paper describes a one-pot procedure for acetamide synthesis directly from amines and pyrimidine ester, without any catalyst or coupling agents. The inexpensive and simple reaction conditions are the most important features of this amidation. This reaction was performed with various amines, showing that long range stabilizing interactions (H-bonding and π-stacking) are the driving force for chemoselectivity.