Amines made easily: a highly selective hydroaminomethylation of olefins

A highly chemo- and regioselective hydroaminomethylation of simple as well as functionalized alpha-olefins using a cationic rhodium precatalyst together with Xantphos as ligand is reported. Studies of the influence of ligands and reaction conditions led to an unprecedented selective hydroaminomethylation procedure. The novel procedure constitutes an economically attractive and environmentally favorable synthesis of secondary and tertiary aliphatic amines.     

Synthesis,Characterization, Thermal Analysis,DFT, and Cytotoxicity of Palladium Complexes with Nitrogen-Donor Ligands

Three new palladium complexes ([Pd(DABA)Cl₂], [Pd(CPDA)Cl₂], and [Pd(HZPY)Cl₂]) bearing dinitrogen ligands (DABA: 3,4-diaminobenzoic acid; CPDA: 4-chloro–o-phenylenediamine; HZPY: 2-hydraziniopyridine) were synthesized, characterized, and tested against breast cancer (MCF-7), prostate carcinoma cell line (PC3) and liver carcinoma cell line (HEPG2). [Pd(DABA)Cl₂] complex exhibited the highest inhibition percentage, lying between 68–71%. The hydrolysis mechanism of each palladium complex, the key step preceding the binding to the biological target, as well as their photophysical properties were explored by means of DFT and TDDFT computations. Results indicate a faster hydrolysis process for the Pd(DABA)Cl₂ complex. The computed activation energies for the first and second hydrolysis processes suggest that all the compounds could reach DNA in their monohydrated form.     

Application of the wavelet transform in the laminar turbulent transition for a flow in a mixed convection phenomenon

The aim of this paper is to show the effect of secondary flows caused by natural convection on the laminar-turbulent hydrodynamic transition. It is not a question of measuring a critical threshold value of Reynolds number of transition but only to estimate the degree of turbulence in the transition regime, i.e. weak turbulence in the case of superposition (mixed convection) or not (forced convection) of secondary flows on the forced flow. This is possible thanks to the application of the wavelet transform. The calculation of the H?lder exponent, associated with the maximum value of the singularity spectrum for two configurations, vertical (forced convection) and horizontal (mixed convection) allows the degree of turbulence to be measured in both cases. The variation of the H?lder exponent versus the Reynolds number has enabled it to be shown that the secondary flows stabilise the main flow and stifle the beginnings of the turbulence during the regime of transition to turbulence; these kinds of results have also been shown in literature. Generally, large-sized secondary flows (for example Dean's flows) stabilise the turbulence. Our work confirms this, through an experiment carried out in identical conditions for mixed convection (horizontal flow) and forced convection (vertical flow). Received 30 March 1998 and Received in final form 28 April 1999     

Elaboration and characterization of organic–inorganic quantum wells impregnated on porous anodic alumina nanostructures

An organic–inorganic quantum well embedded on porous anodic alumina was synthesized and studied by MEB, AFM, optical absorption and photoluminescence. The morphology determined by the MEB and the AFM, shows that the size of the pores is about 10 nm for alumina evaporated on glass substrate and about 35 nm for alumina template prepared in sulfuric acid (H₂SO₄). The optical properties are characterized from absorption and photoluminescence spectra measured at room and low temperature. The measured spectral characteristics demonstrate the influence of the pore size on the emission of the organic–inorganic quantum well ((C₁₂H₂₅NH₃)₂PbI₄). An obvious blueshifted photoluminescence (PL) of (C₁₂H₂₅NH₃)₂PbI₄ in nanometer-sized pores was observed. It results in a better quantum confinement.     

Tonal prediction of a faulty axial fan

The current techniques for monitoring and diagnostics of rotating machines to their conditional predictive maintenance mainly are based on vibration monitoring. In this research, experimental and theoretical methods to predict the tonal noise of a faulty fan are developed and validated. These methods can be used on identifying defects of an axial fan based on an acoustic monitoring in situations where it is necessary to operate remotely due to the inaccessibility of the areas of event defects.     

Electronic structure of ScN, YN, LaN and GdN superlattices

Using the plane wave version of the full potential linear muffin-tin orbital (FPLMTO) method, which enables an accurate treatment of the interstitial regions, the electronic properties of ScN, YN, LaN and GdN rocksalt/rocksalt superlattices are calculated. It is found that apart from YN/ScN, all the other superlattices have negative bandgaps. However, it is shown that these systems can be semiconductors if a correction is made to the local density approximation (LDA).     

Behaviour of an associated conjugate series of a Fourier series

In this paper we obtain a generalisation of a theorem of Mohanty and Ray