Formation of [Bi11]3−, A Homoatomic,Polycyclic Bismuth Polyanion,by Pyridine‐Assisted Decomposition of [GaBi3]2−

Until now, polycyclic bismuth polyanions have not been known—thus discriminating bismuth from its lighter congeners. However, the synthesis of [K([2.2.2]crypt)]₃(Bi₁₁)?2 py?tol, allows us to present the first structurally characterized homoatomic, polycyclic bismuth polyanion, which exhibits the [P₁₁]^3? “ufosan” structure. It was obtained upon treatment of [K([2.2.2]crypt)]₂(GaBi₃)?en with the solvent pyridine. The binary Zintl anion [GaBi₃]^2? decomposes under oxidative coupling of pyridine molecules and release of H₂ to form the title compound. The unprecedented reaction, its products and by‐products were investigated by means of spectroscopy, spectrometry, and DFT studies. All findings reveal the specific reaction conditions to be crucial for the formation of the [Bi₁₁]^3? ion—and indicate the possibility of the generation and isolation of further, large bismuth polyanions.     

Polyphenols in <Emphasis Type="Italic">Coreopsis tinctoria</Emphasis> Nutt. fruits and the plant extracts antioxidant capacity evaluation

The aim of this research was to investigate the chemical composition of Coreopsis tinctoria Nutt. fruits extract, to highlight the potential of ultrasound assisted extraction in the fast preparation of extracts rich in polyphenols using different solvents (55%, 78% and 96% hydrous ethanol) and to evaluate the antioxidant potential of formulated extracts. LC-MS/MS was used to characterize the ethanolic extract from Coreopsis tinctoria Nutt. dried fruits. The extract contains different flavonoids (marein, flavanomarein, quercetagetin-7-O-glucoside, okanin aurone, leptosidin, luteolin, apigenin) and phenolic acids (chlorogenic acid, caffeic acid). Several parameters that could affect extraction efficiency were evaluated. Finally, this study focused on determination of plant extracts total phenolic content and their antioxidant capacity. The experimental results allowed the selection of the optimum operating parameters leading to the highest total polyphenolic content, expressed as gallic acid equivalents, and avoiding the degradation of phenolic compounds (ethanol 55%; extraction temperature 323.15 K, extraction time 30 min, liquid/solid ratio 20/1). A good relationship between total phenolic content and antioxidant capacity was obtained.

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Thermal,spectral, magnetic and biologic characterization of new Ni(II), Cu(II) and Zn(II) complexes with a hexaazamacrocyclic ligand bearing ketopyridine moieties

Five types of fibrous assemblies, namely, polyester, wool, cashmere, kapok, and goose down, were tested for their heat-insulating properties in the natural state using the apparatus developed by the authors. The influences of bulk density, fiber type, fiber arrangements, and compression on the heat-insulating properties of the fibrous assemblies was examined systematically. The results show that kapok assembly with low bulk density, goose down assembly with high bulk density and the randomly arranged fibrous assembly demonstrated the best heat-insulating property; however, considering practical use and the influence of compression, kapok assembly and fibrous assemblies arranged in the form of fiber balls exhibited the most stable and optimum heat-insulating property. The Daryabeigi heat-transfer model that considers fiber contact and scattering effect was used to calculate the heat-insulating properties of the five fibrous assemblies. A similar model was developed by Fanworth, which neglected the fiber and the scattering effect. Comparison of the two models showed that the Daryabeigi model was more accurate in predicting the heat-insulating properties of fibrous assemblies.     

Microwave‐assisted graft polymerization of ε‐caprolactone onto magnetite

The graft polymerization of ε‐caprolactone (ε‐CL) onto magnetite was carried out under microwave irradiation in the presence of tin(II) 2‐ethylhexanoate. The molar ratio of ε‐CL to tin(II) 2‐ethylhexanoate was 300, whereas the molar ratio of ε‐CL to magnetite was 5. The chemical structures of the obtained poly(ε‐caprolactone) coated magnetic nanoparticles were characterized by FTIR and XPS spectroscopy. These magnetic‐polymer hybrid nanostructures were further investigated by X‐ray diffraction and magnetization measurements. The morphology of the magnetic core‐shell nanostructures were determined by TEM. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5397–5404, 2009     

Existence and uniqueness for a nonlinear discrete hyperbolic system

The existence, uniqueness and asymptotic behaviour of the solutions to a nonlinear discrete hyperbolic system subject to some extreme conditions and initial data are investigated in a real Hilbert space.     

Sur les spectres d'absorption infrarouge,entre 2,5 et 16 μ, de semicarbazones

The spectra of 120 semicarbazones in the solide state have been studied between 2.5 and 16 microns in order to correlate absorptions and structures. We have considered most particularly the absorptions v(N-H) and the so-called amid-I and amid-II bands.     

Studies on thermal behavior of some antibacterial copper (II) complex compounds with a dibiguanide derivative ligand

The thermal behavior of six complex compounds of Cu(II) with chlorhexidine as ligand was investigated. The complexes are obtained from chlorhexidine diacetate and copper (II) chloride, bromide and acetate, respectively, in metal:ligand molar ratio 1:1 and 2:1. Thermal decomposition evidenced several well-defined steps as desolvation, anionic moieties release and the ligand cleavage for all complexes. The final residue is in all cases copper (II) oxide.     

Preparation and thermal stability of Al2O3-clay and Fe2O3-clay nanocomposites, with potential application as remediation of radioactive effluents

In the last years metal/clays, aluminosilicates with properties and characteristics of microporous materials, have received more attention, due to the possibility of their use as matrix for nanoparticles encapsulation and stabilization processes. Some types of clays were comparatively evaluated for treating the simulated radioactive wastewater. The raw clay from Valea Chioarului Romania and its pillared forms with Al, Fe, pillars for decontamination of waste-waters with medium and low radioactivity were used. Characterization of the obtained materials was carried out using techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, BET analyses and thermogravimetric analysis (DTG-TG), respectively. Also, the thermal stability of nanocomposites was highly superior to native clay due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system. Clay nanocomposite sample materials were obtained with good thermal stability after calcination. Clay nanocomposites samples were evaluated for remediation of radioactive effluents by treating the radioactive wastes streams. The ion-exchange characteristics and the abilities to uptake radioisotopes of indigene clay from Valea Chioarului area-Romania were examined. The results showed that the precursor used in sample preparation influenced the structural and textural properties of nanocomposites and also capability of prepared modified clay samples by pillaring to be potential candidates for use in connection with environmental protection, remediation of radioactive effluents, respectively.