Mutual Diffusion Driven NMR: a new approach for the analysis of mixtures by spatially resolved NMR spectroscopy

We introduce a new approach for resolving the NMR spectra of mixtures that relies on the mutual diffusion of dissolved species when a concentration gradient is established within the NMR tube. This is achieved by cooling down a biphasic mixture of triethylamine and deuterated water below its mixing temperature, where a single phase is expected. Until equilibrium is reached, a gradient of concentration, from ‘pure’ triethylamine to ‘pure’ water, establishes within the tube. The amount of time required to reach this equilibrium is controlled by the mutual diffusion coefficient of both species. Moreover, a gradient of concentration exists for each additional compound dissolved in this system, related to the partition coefficient for that compound in the original biphasic state. Using slice selective experiments, it was possible to measure these concentration gradients and use them to separate signals from all the present species. We show the results acquired for a mixture composed of n‐octanol, methanol, acetonitrile and benzene and compare them with those obtained by pulse field gradient NMR. Copyright © 2016 John Wiley & Sons, Ltd.     

New antitumour active platinum compounds containing carboxylate ligands in trans geometry: synthesis, crystal structure and biological activity

New asymmetric trans-platinum(II) complexes, composed of an isopropylamine, an azole and two carboxylate leaving groups, are presented. The crystal and molecular structures of one of the complexes has been determined and the cytotoxicity and reactivity with 5'-guanosine monophosphate is reported. The complexes show a reduced reactivity, but no decrease in cytotoxic activity compared to their chloro-counterparts. Furthermore the complexes largely overcome cisplatin resistance, they therefore present an interesting class of antitumour active trans-platinum complexes.     

Tin colloids and metal-metal oxide films prepared by chemical liquid deposition. III

Colloids and thin metal-metal oxide films have been prepared by a method we call Chemical Liquid Deposition (CLD). The metal is evaporated to yield atoms which are solvated at liquid nitrogen temperature, and upon warming stable liquid colloidal solutions are formed. In the case of tin, the particle size of these colloids ranges between 200–500 Å. Zeta potentials were calculated by a Hückel approximation for most of these negatively charged particles. Upon solvent removal, colloidal particles coalesce to form films, which contain some residual solvent. The synthesis of colloids and films from Sn with acetone, 2-butanone, THF, ethanol, 2-propanol, DMF and DMSO is reported. FTIR, High Resolution Mass Spectrometry, Thermogravimetric Analyses (TGA) and Scanning Electron Microscopy (SEM) film characterization has been carried out. These studies indicate that solvents are incorporated into the films. The resistivity studies showed that they more behave as semiconductors than pure metals. TGA studies reveal that loss of weight occurs within 200–500°C. The films are very stable with 5–10% weight loss at 550°C. SEM reveals their surface morphology. Mössbauer gives information about oxidation states of some tin films.     

Bruhat Presentations for ∗-Classical Groups

We introduce in a general setting, the unitary similitude groups associated to ε-hermitian form over a ring A with involution. We concentrate next in the rank 2 case. The classical presentation of GL(2, F), F a field, originating from its Bruhat decomposition can be extended to these unitary similitude groups. Furthermore, the multiplier associated to ε-hermitian forms affords a signed non commutative version of the classical determinant of 2 by 2 matrices, which we recover exploiting Grassmann's approach to determinants. Finally, we present various examples of our groups and give some categorical properties of them.     

Shape memory ionomers

This review is focused on the use of ionomers in shape memory polymers. Ionomers are polymers that contain less than ∼15% ionic groups. The incompatibility between the ion-pairs and the polymer backbone drives microphase separation producing dispersed ionic aggregates, which can physically crosslink the polymer. Shape memory polymers are responsive materials that can be deformed to program a temporary shape and then recovered on application of an external stimulus. Through the review of the main types of ionomers used in shape memory polymers, polyurethanes and polyester ionomers, polyolefin and polyaromatic ionomers, and perfluorosulfonic acid ionomers (i.e., Nafion^®) it will be shown that ionomers can produce robust thermoplastic shape memory polymers and in many cases impart unique properties which allow advanced shape memory materials to be obtained including antibacterial, high temperature, and multishape memory polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1389–1396     

ChemInform Abstract: Structural Properties and Singular Phase Transitions of Metallic Pr0.50Sr0.50CoO3 Cobaltite.

Two successive magnetic transitions of Pr_0.50Sr_0.50CoO₃ contrast with the single ferromagnetic transition in other Ln_0.50Sr_0.50CoO₃ compounds.     

Optimization of MHD nanofluid flow in a vertical microchannel with a porous medium,nonlinear radiation heat flux,slip flow and convective–radiative boundary conditions

Journal of Thermal Analysis and Calorimetry - The optimization of a magnetohydrodynamic flow of Al2O3–water nanofluid was carried out numerically considering the combined effects of various...     

Analysis of hydrolysis process of γ-methacryloxypropyltrimethoxysilane and its influence on the formation of silane coatings on 6063 aluminum alloy

In this paper the hydrolysis process of γ-methacryloxypropyltrimethoxysilane (MPS) at 1% in an aqueous solution by means of Fourier transform infrared (FTIR) spectroscopy was studied. The aim of this work is to determine the hydrolysis time for which a greater number of Si-OH groups has been obtained. Different hydrolysis times at pH 4 were studied to establish the most optimal application conditions for bonding to the substrate. It was possible to observe how the bands corresponding to the Si-O-C groups present in the pure silane spectrum continued to appear after short periods of hydrolysis. However these bands practically disappeared upon increasing of this hydrolysis time, with other new ones appearing corresponding to the Si-OH vibration. The silanization of 6063 aluminum alloy samples was also carried out. Analysis of the silane layers by means of FTIR indicated that the immersion time may be important according to the hydrolysis conditions, and it also allowed optimizing the drying time.