Synthesis and characterization of three new organotin complexes containing piperazine as a bidentate ligand

The reaction of dichlorostannanes R₂SnCl₂ (R=Me 1, Buⁿ 2) with piperazine ligand in molar ratio 1:2, in dry methylene dichloride, in an inert atmosphere leads to the synthesis of R₂Sn(C₄H₉N₂)₂(R=Me 1, Buⁿ 2). In a similar manner, The reaction between Ph₂SnCl₂ and piperazine in dry ethanol in molar ratio 1:1 produces [Ph₂Sn(C₄H₈N₂)]₂ (3). The yields of these new products were excellent and they have been fully characterized by FT-IR, UV–Vis, multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR spectroscopy and mass spectrometry, as well as elemental analysis. The spectroscopic results indicate that the piperazine ligand is coordinated to tin atom of organotin moieties, through the nitrogen atoms. Furthermore, the ligand behaves as a bidentate fashion in (1) and (2) and gives 1:2 substitution products, while in the complex (3) the two six-membered rings bind in bidentate-chelate forms between the two Sn atoms.     

CuI-catalyzed tandem synthesis of thioethers using aryl halides,electron-deficient alkenes,and sodium iso-propyl xanthogenate

A ligand-free, CuI-catalyzed protocol was developed for the one-step preparation of Michael adducts of aromatic thiols in high yields by reacting a mixture of an aryl halide and an electron-deficient alkene with sodium iso-propyl xanthogenate.     

Spacecraft formation flying in the port-Hamiltonian framework

The problem of controlling the relative position and velocity in multi-spacecraft formation flying in the planetary orbits is an enabling technology for current and future research. This paper proposes a family of tracking controllers for different dynamics of Spacecraft Formation Flying (SFF) in the framework of port-Hamiltonian (pH) systems through application of timed Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC). The leader–multi-follower architecture is used to address this problem. In this regard, first we model the spacecraft motion in the pH framework in the Earth Centered Inertial frame and then transform it to the Hill frame which is a special local coordinate system. By this technique, we may present a unified structure which encompasses linear/nonlinear dynamics, with/without perturbation. Then, using the timed IDA-PBC method and the contraction analysis, a new method for controlling a family of SFF dynamics is developed. The numerical simulations show the efficiency of the approach in two different cases of missions.

     

Recent developments of metallic nanoparticles and their catalytic activity in organic reactions

During the last two decades, with the development of nanotechnology, various nanomaterials have been designed and generated. Among them, hybrid organic–inorganic nanoparticles as a particular immobilizing carrier of the catalyst active sites have shown an important contribution in the current research studies. This is due to the large area and loads of active sites. This prominent review is focused on the novel various exa about the immobilization of nanoparticles with organic compounds as versatile and efficient catalysts in organic syntheses.     

Enhancing endothelial differentiation of human mesenchymal stem cells by culture on a nanofibrous polycaprolactone/(poly-glycerol sebacate)/gelatin scaffold

Cardiovascular diseases have always been one of the main causes of death worldwide and eventually one of the major medical concerns. Tissue engineering is promising strategies of treating cardiovascular, which can be an effective approach with the design of appropriate scaffold. In this study, to develop engineering basement membrane for endothelial differentiation with good cell attachment, we produced polycaprolactone (PCL)/poly (glycerol sebacate) (PGS)/gelatin nanofibrous scaffold via electrospinning. Attenuated total reflectance-Fourier transform infrared and the proton nuclear magnetic resonance results confirmed the chemical structure of synthesized PGS. Scanning electron microscope images of the electrospun scaffold revealed that the nanofibers are smooth, continues and uniform. Moreover, due to the presence of hydrophilic functional groups in the scaffold, the contact angle is in the appropriate range for cell adhesion especially endothelial cells. The elastic modulus and ultimate tensile stress of electrospun scaffold were calculated 1.32 ± 0.27 MPa and 1.23 ± 0.18 MPa respectively. Quantitative polymerase chain reaction was performed for evaluation of endothelial differentiation of mesenchymal stem cells cultured on standard plate and fibrous scaffold under chemical stimulation with growth factor. Specific endothelial gene expression results postulated that our modified scaffold could support and significantly promote endothelial differentiation of MSCs.     

One-pot,direct synthesis of acyl azides from carboxylic acids using Ph2PCl/I2/NaN3 reagent system

A mild,efficient and simple method for the preparation of acyl azides from carboxylic acids using chlorodiphenylphosphine in the presence of molecular iodine and sodium azide is described.     

Nanostructured Colloidal Solutions of Malachite Green Formulated: Nonlinear Optical Properties and Simulation

Journal of Fluorescence - Malachite green (MG) is a dye that has been presented to use as photosensitizers for photodynamic therapy (PDT). Nonlinear absorption coefficient (β) and nonlinear...     

On the Schröder–Bernstein property for modules

The well known Schröder–Bernstein Theorem states that any two sets with one to one maps into each other are isomorphic. The question of whether any two (subisomorphic or) direct summand subisomorphic algebraic structures are isomorphic, has long been of interest. Kaplansky asked whether direct summands subisomorphic abelian groups are always isomorphic? The question generated a great deal of interest. The study of this question for the general class of modules has been somewhat limited. We extend the study of this question for modules in this paper. We say that a module Msatisfies the Schröder–Bernstein property (S-B property) if any two direct summands of M which are subisomorphic to direct summands of each other, are isomorphic. We show that a large number of classes of modules satisfy the S-B property. These include the classes of quasi-continuous, directly finite, quasi-discrete and modules with ACC on direct summands. It is also shown that over a Noetherian ring R, every extending module satisfies the S-B property. Among applications, it is proved that the class of rings R for which every R-module satisfies the S-B property is precisely that of pure-semisimple rings. We show that over a commutative domain R, any two quasi-continuous subisomorphic R-modules are isomorphic if and only if R is a PID. We study other conditions related to the S-B property and obtain characterizations of certain classes of rings via those conditions. Examples which delimit and illustrate our results are provided.