Here we report syntheses and study of composite solid polymer electrolytes (SPEs) based on a poly(ethylene glycol)-in-Li triflate material that contains an organic-inorganic composite (OIC) in which boron species are incorporated into a silica network. The structure and properties of the SPEs synthesized were characterized by scanning transmission electron microscopy (STEM), 29 Si, 11 B and 13 C solid state NMR, differential scanning calorimetry, and impedance spectroscopy. STEM allowed assessment of OIC particles in their native environment without removal of an organic component. The Lewis acid tricoordinate boron sites formed in OIC are proposed to have a stronger interaction with triflate anions than silica sites, which results in enhanced lithium ion conductivity and Li transference numbers at optimal boron concentrations. The optimum triethyl borate (TEB) concentration also leads to formation of smaller (higher surface area) OIC particles, which expose more boron sites to triflate anions. The SPE sample prepared with 10 mol% TEB exhibited a conductivity of 4.3 Â 10 À5 S cm À1 and a Li transference number of 0.89, which represents nearly single-ion conductor behaviour for the salt-in-polymer-borosilicate composite.
We report a novel method for synthesis of alloy PtFe nanoparticles (NPs) of different compositions using γ-Fe2O3 NPs as an iron source. We show here other growth mechanisms than conventional nucleation on a NP surface leading to core-shell NP or seeded NP growth. Depending on reaction conditions, different compositions of PtFe NPs can be obtained. PtFe NPs may coexist with γ-Fe2O3 NPs in the reaction product. This mixture obtained in situ allows much higher catalytic activity in hydrogenation of methyl-3-buten-2-ol than that of only PtFe nanoparticles or merely mixed PtFe and γ-Fe2O3 NPs. The presence of both PtFe and γ-Fe2O3 NPs allows formation of dense and stable NP arrays which hold promise for catalytic applications in microreactors or other reactor designs where a catalytic film is favoured.
For the first time the four block copolymers derived from 1-alkyl[2-(acryloyloxy)ethyl]dimethylammonium bromides with hexyl (ADA) or cetyl (ADHA) groups and 2-hydroxyethylacrylate (HEA) or N-isopropylacrylamide (NIPAM) were synthesized and employed for functionalization of monodisperse iron oxide nanoparticles (NPs). The polyADA (pADA) or polyADHA (pADHA) block consists of long hydrophobic tails (C(6) or C(16)) connected to a positively charged quaternary ammonium group, making this block amphiphilic. The second block was either fully hydrophilic (pHEA) or thermoresponsive (pNIPAM). The dependence of the NP coating on the length of the hydrophobic tail in the amphiphilic block, the composition of the hydrophilic block, and the NP sizes have been studied. Unusual self-assembling of iron oxide NPs into well-defined composite submicrometer particles was observed for pADHA-b-pNIPAM in the wide range of concentrations (at the pADHA repeating unit concentrations of 0.065 × 10(-2)-2.91 × 10(-2) mmol/mL per 1 mg/mL NPs) but only two concentrations, 1.62 × 10(-2) and 1.94 × 10(-2) mmol/mL, led to regular spherical particles. The thermoresponsive behavior of these composite particles was tested using ζ-potential and dynamic light scattering measurements, while the morphology of particles was characterized by transmission electron microscopy. Coating of NPs with pADHA-b-pHEA results in the formation of individually coated NPs. The different composite particle morphologies are explained by different properties of pHEA and pNIPAM. It is demonstrated that the composite particles based on pADHA-b-pNIPAM are responsive to a magnetic field and can be recommended as magnetic stoppers in biorelated membrane separations. The incorporation of Pd species in submicrometer particles makes them promising candidates for catalytic applications as magnetically recoverable catalysts with a high magnetic response.
Q fever in solid organ transplant (SOT) recipients is rarely described in the medical literature. We present a case of severe acute Q fever pneumonia that evolved into persistent localized Q fever endocarditis in a renal transplant recipient.
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