Search results for "Composite"
showing 10 items of 4584 documents
Regioselective C–H amination of free base porphyrins via electrogenerated pyridinium-porphyrins and stabilization of easily oxidized amino-porphyrins…
2020
Four free base aminoporphyrins were synthesized in two steps via regioselective anodic nucleophilic substitution with pyridine followed by ring opening of the electrogenerated pyridinium with piperidine. The X-ray crystallographic structure of the unstable 2-aminotetraphenylporphyrin was solved. Protonation of this latter compound leads to the stable diiminium porphyrin salt.
Prussian blue films deposited on graphite+epoxy composite electrodes: electrochemical detection of the second percolation threshold
2000
Abstract The electrochemical behavior of Prussian blue films galvanostatically electrodeposited on graphite+epoxy-resin composite electrodes was studied. The composite electrodes were prepared with different graphite proportions and their effect on electrochemical reduction of the Prussian blue was analyzed by means of the uncompensated resistance approximation and the electrical percolation theory. The results suggest that the electrode with 60% graphite reaches the second percolation threshold and its internal structure changes from a compact to a porous one. Mechanical tensile tests were performed in order to confirm the critical behavior of this material at the percolation thresholds. T…
One-stage periodical anodic-cathodic double pulse deposition of nanocomposite materials. Application to Prussian Blue/polypyrrole film coated electro…
2014
Abstract Novel electrochemical method of one-stage deposition of composite films on electrode surface has been proposed. The procedure includes a periodical series of potentiostatic or galvanostatic pulses of alternative polarity imposed at electrode in contact with a mixture of two solute precursors, one of which is able to generate a solid phase under its electrooxidation while another one is transformed into another solid phase under its electroreduction. Parameters of anodic and cathodic pulses (potential or current, pulse duration) may be chosen independently from one another, their relation allows one to vary the relative contents of components in the deposited composite. Thickness of…
Spin polarization in electrodeposited thin films of the molecule-based magnetic semiconductor Cr5.5(CN)12·11.5H2O
2013
The magnetoresistance (MR) effect of thin films of the Prussian Blue Analogue (PBA) Cr5.5(CN)12·11.5H2O, prepared by electrochemical deposition, has been measured using the standard two-point probe method. This molecule-based ferrimagnetic material, with a Tc = 240 K, exhibits MR up to 2% at 6 T and 200 K.
Polyanion–tobramycin nanocomplexes into functional microparticles for the treatment of Pseudomonas aeruginosa infections in cystic fibrosis
2016
Aim: Efficacy of antibiotics in cystic fibrosis (CF) is compromised by the poor penetration through mucus barrier. This work proposes a new ‘nano-into-micro’ approach, used to obtain a combinatorial effect: achieve a sustained delivery of tobramycin and overcome mucus barrier. Methods: Mannitol microparticles (MPs) were loaded with a tobramycin polymeric nanocomplex and characterized in presence of CF artificial mucus. Results & discussion: MPs are able to alter the rheological properties of CF artificial mucus, enhancing drug penetration into it and allowing a prolonged drug release. MPs resulted to be effective in Pseudomonas aeruginosa infections if compared with free tobramycin. Co…
Modelling of Moisture Sorption by Cfrp Rebars with Vinylester Matrix
2004
The results of experimental investigation and modelling of moisture sorption by CFRP rebars and vinylester matrix are presented. Experimental values of the rebar diffusion coefficients essentially differ from those predicted using structural approach. Essential anisotropy of sorption process in longitudinal and transverse directions is observed. Quasi three phase model is suggested for description of the CFRP rebar sorption. The model is based on consideration of sorption process of the diffusion character in the composite consisted of two phases: resin and microplastic, which includes fibres and fibre-resin interphase. The suggested model describes the experimental sorption data quite sat…
Iatrogenic acute aortic dissection type A: insight from the German Registry for Acute Aortic Dissection Type A (GERAADA)†
2013
OBJECTIVES: Previous investigators have reported a grave prognosis for iatrogenic acute aortic dissection (iAADA), but such studies are limited by their small sample sizes. The purpose of the current study was to analyse the clinical characteristics, current management and surgical outcomes in a large number of iAADA patients identified through a multicentre registry. METHODS: Between July 2006 and June 2010, 50 centres participated in the German Registry for Acute Aortic Dissection Type A (GERAADA). Of the 2137 patients included, 100 (5%) had iAADA. We compared the clinical features and 30-day outcomes of patients with iatrogenic and spontaneous acute aortic dissection type A (sAADA). RESU…
Publisher Correction: X-Ray Nanotomography of Individual Pulp Fibre Bonds Reveals the Effect of Wall Thickness on Contact Area
2020
Fibre bonds play an essential role in various properties of paper. Much research has focused on their strength, but the determination of the actual contact area also provides a challenge. Many of the research methods rely on optical tools, which are restricted by the wavelength of light that is utilised. Novel X-ray computed tomography devices utilise X-rays in studying the inner structure of materials, and surpass the optical methods in terms of resolution, allowing detection of even smaller details and variations in distance between the fibres in the bond intersection area. X-ray nanotomography was used to image 26 individual cellulose fibre bonds made of springwood and summerwood fibres …
H(II) centers in natural silica under repeated UV laser irradiations
2004
We investigated the kinetics of H(II) centers (=Ge'-H) in natural silica under repeated 266nm UV irradiations performed by a Nd:YAG pulsed laser. UV photons temporarily destroy these paramagnetic defects, their reduction being complete within 250 pulses. After re-irradiation, H(II) centers grow again, and the observed recovery kinetics depends on the irradiation dose; multiple 2000 pulses re-irradiations induce the same post-irradiation kinetics of H(II) centers after each exposure cycle. The analysis of these effects allows us to achieve a deeper understanding of the dynamics of the centers during and after laser irradiation.
Experimental and numerical assessment of subsurface plastic deformation induced by OFHC copper machining
2015
Strain distributions in the machined surface and subsurface of OFHC copper workpieces were determined experimentally and through numerical simulations. An experimental setup, comprising a double frame camera and a pulsed laser, was developed to measure the displacement fields using the digital image correlation (DIC) technique; strain distributions were then calculated. A numerical orthogonal cutting model was also developed and applied in order to predict such distributions. Comparison between simulated and measured results enabled an understanding of the fundamental mechanisms of plastic deformation of the machined surface of OFHC copper.; International audience; Strain distributions in t…