Determination of <Superscript>99</Superscript>Tc in environmental samples and depleted uranium penetrators using ICP-MS

A new method was developed for the determination of ⁹⁹technetium (Tc) by ICP-MS. We report, for the first time, an activity of ⁹⁹Tc for the reference material IAEA-315. For the IAEA-375, IAEA-373 and IAEA-381, our results confirmed the values already reported in the literature. The developed method was used for analysing sediments from the Yenisei river (collected downstream of a nuclear fuel reprocessing plant) and for characterizing corrosion products of depleted uranium penetrators that were fired during the Balkan conflict.     

Iridium-Catalyzed Oxidant-Free Dehydrogenative CH Bond Functionalization: Selective Preparation of N-Arylpiperidines through Tandem Hydrogen Transfers

Relay to the finish: The atom-economical tandem hydrogen autotransfer catalyzed by iridium(III) has been efficiently applied for the preparation of N-arylpiperidines starting from easily accessible anilines, diols, and aldehydes. This protocol is also compatible with the use of diethyl carbonate as an ecofriendly solvent.     

Pressure effect on mechanical stability and ground state optoelectronic properties of Li2S2 produced by Lithium−Sulfur batteries discharge: GGA-PBE,GLLB-SC and mBJ investigation

ABSTRACT

According to several previous works, Li₂S₂ occurs during discharge of lithium–sulfur (Li–S) batteries. Several information on the physical properties of this compound remain unknown including those of its ground state. In this work, a study of the pressure effect on the elastic and optoelectronic properties of Li₂S₂ in its tetragonal structure of P4₂/mnm space group was carried out. According to the previous works and according to the structural results, which have been obtained by GGA-PBE and optPBE-vdW funtionals, we have found that P4₂/mnm-Li₂S₂ energy is the lowest compared to other studied structures (P6₃/mmc, P-62m and Immm), this can indicate that P4₂/mnm space group structure may represent its ground state structure. The study of the pressure effect on the elastic properties has shown that P4₂/mnm-Li₂S₂ maintains its mechanical stability for a pressure range between 0 and 2.5?GPa. The study of the directional dependence of Young's modulus has shown that it is anisotropic and therefore indicates the elastic anisotropy of the studied compound. According to the electronic results, the fundamental band-gap of P4₂/mnm-Li₂S₂ is of an indirect nature, its values found by mBJ and GLLB-SC are close to each other. The pressure effect on the possible transitions between the valence band top and the conduction band bottom and on the variations of the refractive index and the absorption coefficient according to both optical directions has been studied by determining the dielectric function. The found optical results have shown that P4₂/mnm-Li₂S₂ has negative uniaxial birefringence.     

Isoquinoline derivatives via stepwise regioselective sp(2) and sp(3) C-H bond functionalizations

Efficient and practically attractive stepwise ruthenium- and palladium-catalyzed regioselective C-H bond functionalizations were achieved to produce 4-substituted tetrahydroisoquinoline derivatives featuring various heteroaromatic substructures in moderate to good yields. Both ruthenium- and palladium-based catalytic processes generated nontoxic and easily separable side products.     

Deposition of SiO2-Like Films by HMDSN/O2 Plasmas at Low Pressure in a MMP-DECR Reactor

The effects of process parameters such as O₂/HMDSN (hexamethyldisilazane) ratio, microwave discharge power and deposition pressure on the growth rate, chemical bonding nature, and refractive index of thin films deposited by microwave plasma from HMDSN with oxygen, have been investigated. The plasma was created in a Microwave Multipolar reactor excited by Distributed Electron Cyclotron Resonance. The films were deposited at room temperature and characterized by Fourier Transform Infrared spectroscopy and ellipsometry. Growth rate increased with the discharge power P or the deposition pressure but decreased significantly with increasing O₂/HMDSN ratio. A large change in the film composition was observed when the O₂/HMDSN ratio was varied: films deposited with only HMDSN precursor are polymer-like but as the O₂/HMDSN ratio increased, organic groups decreased. For relative pressure values over 70%, deposited films are SiO₂-like with refractive index values close to those found for thermal silicon dioxide.     

The effect of the excitation and of the temperature on the photoluminescence circular polarization of AlInAs/AlGaAs quantum dots

In this paper, we present a study of photoluminescence (PL) from AlInAs/AlGaAs quantum dots (QDs) structures grown by molecular beam epitaxy. Specifically, we describe the effects of the temperature and of the excitation density on the photoluminescence circular polarization. We have found that the circular polarization degree depends on temperature. On the other hand, the study of the excitation density dependent circular polarization PL degree shows that the last increases in the case of the sample of weak dot density. However, in the case of large dot density, it is almost constant in the excitation density range from 0.116 W cm⁻² to 9 W cm⁻².     

Preparation of chiral ruthenium(IV) complexes and applications in regio- and enantioselective allylation of phenols

Facile preparations of chiral [Ru(Cp*)]- and [Ru(Cp')]-based allyl complexes featuring N,O chelate derived from (+)-nopinone are described. Single crystal X-ray structural analysis of one complex revealed the preferential configuration of the ruthenium centre and the orientation of the unsymmetrical allylic substituent. Applications of these complexes in catalysis for nucleophilic allylic substitution allowed regio- and enantioselective formation of branched allyl ethers from phenols.