Fundamentals and development of high‐efficiency supported catalyst systems for atom transfer radical polymerization

Atom transfer radical polymerization (ATRP) is a controlled/living radical polymerization process developed a decade ago that allows the synthesis of tailored macromolecules. It has been widely used in the laboratory for polymer synthesis since but little use has been made of it at the industrial scale for polymer production. This is due to the low activity of the ATRP catalyst that is central to the process. Much work has been done over the years to overcome this challenge, and the greatest successes have been achieved through catalyst supporting and recycling. We present here a historical account of the development of supported ATRP catalysts while shedding light on their present and future challenges. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 553–565, 2007     

Determination of rapeseed methyl ester oil volumetric properties in high pressure (0.1 to 350 MPa)

The isothermal compressibility coefficient, the bulk modulus, the cubic expansion coefficient, the density and the propagation speed of the pressure waves of rapeseed methyl ester oil (RMEO) are the thermophysical properties derived from the specific volume determined in this work and compared with the properties of diesel oil (DO). The temperature measurement interval ranges from 288.15 to 328.15 K and the pressure measurement interval from atmospheric pressure to 350 MPa. The experimental method used consisted of a volume change cell characterised by a linear variable differential transformer (LVDT) magnetic induction system adapted to a high-pressure vessel. To calculate the properties the modified Tait-Tammann equation was used and a high correlation coefficient was obtained with a 95% confidence level. The specific volume and compressibility coefficient were greater for DO than for RMEO; also, cubic expansion was greater for DO than for RMEO. These results pave the way for further practical application.     

Metal-promoted allylation, propargylation, or allenylation of azetidine-2,3-diones in aqueous and anhydrous media. Application to the asymmetric synthesis of densely functionalized 3-substituted 3-hydroxy-beta-lactams.

Metal-mediated carbonyl allylation, allenylation, and propargylation of optically pure azetidine-2,3-diones were investigated in both anhydrous and aqueous environments. Different metals promoters showed varied regioselectivities on product formation during allenylation/propargylation reactions of the keto-beta-lactams. The stereochemistry of the new C3-substituted C3-hydroxy quaternary center was controlled by placing a chiral auxiliary at C4. In this way, the coupling of azetidine-2,3-diones with a variety of propenyl-, propynyl-, and allenylmetal reagents offers a convenient asymmetric entry to potentially bioactive 3-substituted 3-hydroxy-beta-lactams.     

Sol-gel preparation of In2O3-Al2O3 supports with controlled textural and structural properties

Alumina supports with a very narrow pore size distribution were obtained with indium-doped alumina prepared by the sol-gel method. The formation of aluminum in pentahedral coordination was identified by ²⁷Al NMR-MAS-spectroscopy. A good correlation was obtained with the Al^V NMR-MAS intensity signal and the activity in isopropanol dehydration. The insertion of In³⁺ substituting some Al³⁺ in the alumina network was suggested.     

High-temperature tungsten trioxides obtained by concentrated solar energy: physicochemical and electrochemical characterization

Journal of Solid State Electrochemistry - High-crystalline tungsten trioxides (WO3) have been synthesized by an environmentally friendly method using concentrated solar energy. The obtained...     

Novel and Versatile Cobalt Azobenzene-Based Metal-Organic Framework as Hydrogen Adsorbent

A novel URJC-3 material based on cobalt and 5,5′-(diazene-1,2-diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC-3, with polyhedral morphology, crystallizes in the tetragonal and P4₃2₁2 space group, exhibiting a three-dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77–298 K) and pressures (1–170 bar). The hydrogen storage capacity of URJC-3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single-walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials.     

Cocyclic two-circulant core Hadamard matrices

Journal of Algebraic Combinatorics - The two-circulant core (TCC) construction for Hadamard matrices uses two sequences with almost perfect autocorrelation to construct a Hadamard matrix. A...     

Numerical simulations of paper-based electrophoretic separations with open-source tools

A new tool for the solution of electromigrative separations in paper-based microfluidics devices is presented. The implementation is based on a recently published complete mathematical model for describing these types of separations, and was developed on top of the open-source toolbox electroMicroTransport , based on OpenFOAM^®, inheriting all its features as native 3D problem handling, support for parallel computation, and a GNU GPL license. The presented tool includes full support for paper-based electromigrative separations (including EOF and the novel mechanical and electrical dispersion effects), compatibility with a well-recognized electrolyte database, and a novel algorithm for computing and controlling the electric current in arbitrary geometries. Additionally, the installation on any operating system is available due to its novel installation option in the form of a Docker image. A validation example with data from literature is included, and two extra application examples are provided, including a 2D free-flow IEF problem, which demonstrates the capabilities of the toolbox for dealing with computational and physicochemical modeling challenges simultaneously. This tool will enable efficient and reliable numerical prototypes of paper-based electrophoretic devices to accompany the contemporary fast growth in paper-based microfluidics.     

On the birth of stall cells on airfoils

Critical point theory asserts that two-dimensional topologies are defined as degeneracies and any three-dimensional disturbance of a two-dimensional flow will lead to a new three-dimensional flowfield topology, regardless of the disturbance amplitude. Here, the topology of the composite flowfields reconstructed by linear superposition of the two-dimensional flow around a stalled airfoil and the leading stationary three-dimensional global eigenmode has been studied. In the conditions monitored the two-dimensional flow is steady and laminar and is separated over a fraction of the suction side, while the amplitudes considered in the linear superposition are small enough for the linearization assumption to be valid. The multiple topological bifurcations resulting have been analysed in detail; the surface streamlines generated by the leading stationary global mode of the separated flow have been found to be strongly reminiscent of the characteristic stall cells, observed experimentally on airfoils just beyond stall in both laminar and turbulent flow.     

Quantitative proton magnetic resonance determination of N,N‐dimethylformamide in one intermediate of the Quimi‐Hib vaccine

Quimi‐Hib is a conjugate vaccine against Haemophilus influenza type b (Hib) where the Hib antigen is the only one produced by chemical synthesis. NMR has become the alternative of choice for the identity of intermediates during the chemical synthesis of Hib antigen. We explore a rapid quantitative proton magnetic resonance (qHNMR) assay for the determination of N,N‐dimethylformamide (DMF) as a residual in one of the critical intermediates. The proposed assay has been shown to be accurate, precise for intermediate precision conditions (relative standard deviation <3% for spectrometer‐to‐spectrometer variations), specific (no detected interferences), and rugged (percentage difference <3% for day‐to‐day and spectrometer‐to‐spectrometer variations). The quantitative NMR assay can replace the common chromatographic methods for monitoring the DMF contents in one crucial step of the synthetic scheme. Copyright © 2012 John Wiley & Sons, Ltd.