Evidences for liquid encapsulation in PMMA ultra-thin film grown by liquid injection Photo-CVD

This paper deals with the characterization of ultra-thin films of PMMA grown by an original photo-assisted Chemical Vapor Deposition process equipped with a pulsed liquid injection system to deliver the monomer. The nanometric thick films showed a good ability to encapsulate a liquid phase as microdroplets protected by a thin polymeric tight membrane in the form of blisters. Techniques that are capable to analyze these heterogeneous structures at micro- and nanoscopic scale such as Raman Confocal Spectroscopy and Atomic Force Microscopy were used to characterize these polymer films. The liquid droplets were found to be monomer encapsulated by a PMMA film. The specific properties of these ultra-thin films exhibit self-healing capabilities at microscopic scale making them attractive for functionalization of surfaces and interfaces.     

New Bismaleimide-Epoxy Resin System

New functional epoxy resins were prepared by the reaction of dialyldiglycicylbisphenol A (DADGBPA) with diaminodiphenylmethane. DADGBPA was prepared by reaction of o,o′-diallylbisphenol A with epichlorhydrine. By reaction of functional epoxy resins with bismaleimides, new epoxy-bismaleimide resins with good thermostability were obtained. The thermal properties of epoxy resins and epoxy-bismaleimide resins were determined by DSC and TGA measurements.     

Re-Mendable Polyurethanes

Novel re-mendable polyurethanes were prepared by the Diels-Alder cycloaddition reaction of urethane bismaleimides to bisfuryl monomers. The urethane bismaleimides were synthesized by an addition reaction of 4-maleimidophenylisocyanate to macrodiols, such as polycaprolactone diol (M_n ? 1250 and 2000), PEA-2000 and PBA-2000. The bisfuryl monomers were obtained by the reaction of 2-furfuryl alcohol with hexamethylene diisocyanate or by open-ring reaction of the oxirane ring from diglycidyl bisphenol A with furfuryl amine.     

Determination of Diosmin in Pharmaceutical Products with Chemically Modified Voltammetric Sensors

In this paper, the electrochemical behavior of two types of sensors based on modified screen-printed electrodes (one screen-printed electrode based on carbon (SPCE) and another screen-printed electrode modified with Prussian Blue (PB/SPCE)) was studied with the aim of sensitive detection of diosmin, an active pharmaceutical compound from the class of flavonoids. The scan electron microscopy technique was used for the morphological characterization of PB/SPCE. The preliminary analysis assessed the electrochemical behavior of SPCE and PB/SPCE in KCl solution and in a double solution of potassium ferrocyanide–potassium chloride. It was shown that the active area of PB/SPCE is superior to the one of SPCE, the greater sensitivity being related with the presence of the electroactive modifier. Similarly, in the case of diosmin detection, the PB/SPCE sensor detect more sensitivity the diosmin due to the electrocatalytic effect of PB. From the study of the influence of reaction rate on the sensor’s electrochemical response, it was shown that the detection process is controlled by the adsorption process, the degree of surface coverage with electroactive molecules being higher in the case of PB/SPCE. From the PB/SPCE calibration curve, it wasdetermined that it has high sensitivity and low detection and quantification limit values (limit of detection 5.22 × 10⁻⁸ M). The applicability of the PB/SPCE sensor was confirmed by sensitive analysis of diosmin in pharmaceutical products. The voltammetric method is suitable for the detection and quantification of diosmin in pharmaceutical products. The method is simple, accurate, and quick and can be used in routine analysis in the examination of the quality of pharmaceutical products and other types of samples.     

Simulation der Gefügeentwicklung beim Stabwalzen von Rippenstahl

The steel and rolling mill Marienhütte GmbH in Graz produces reinforcing steel BSt 550 by means of tempcore process with a bainitic/martensitic edge zone and a ferritic/pearlitic core. After the cooling section the edge zone is directly annealed by the rolling heat. The temperature and microstructure development, as well as the resultant mechanical properties, are computed by a finite differences model. The influencing parameters cooling rate, rolling speed as well as range of the chemical composition are observed and evaluated.     

Stress‐Temperature‐Transformation and Deformation‐Temperature‐Transformation Diagrams for an Austenitic CrMnNi as‐cast Steel

Stress‐Temperature‐Transformation (STT) and Deformation‐Temperature‐Transformation (DTT) diagrams are well‐suited to characterize the TRIP (transformation‐induced plasticity) and TWIP (twinning‐induced plasticity) effect in steels. The triggering stresses for the deformation‐induced microstructure transformation processes, the characteristic temperatures, the yield stress and the strength of the steel are plotted in the STT diagram as functions of temperature. The elongation values of the austenite, the strain‐induced twins and martensite formations are shown in the DTT diagram. The microstructure evolution of a novel austenitic Cr‐Mn‐Ni (16%Cr, 6% Mn, 6% Ni) as‐cast steel during deformation was investigated at various temperatures using static tensile tests, optical microscopy and the magnetic scale for the detection of ferromagnetic phase fraction. At the temperatures above 250 °C the steel only deforms by glide deformation of the austenite. Strain‐induced twinning replaces the glide deformation at temperatures below 250 °C with increasing strain. Below 100 °C, the strain‐induced martensite formation becomes more pronounced. The kinetics of the α'‐martensite formation is described according to stress and deformation temperatures. The STT and DTT diagrams, enhanced with the kinetics of the martensite formation, are presented in this paper.     

Effects of SiO2 and Al2O3 nanofillers on polyethylene properties

Polymers filled with inorganic nanoparticles have become interesting materials as dielectrics because of their improved mechanical and electrical properties compared with the unfilled polymers and with polymer microcomposites. These improvements are mainly due to the large surface area of nanoparticles and new polymer–nanofiller interface characteristics. In the present work, polyethylene nanocomposites with SiO₂ and Al₂O₃ nanoparticles were prepared by melt mixing. Mechanical and electrical properties of these composites were determined and morphological aspects were revealed by scanning electron microscopy, wide‐angle X‐ray diffraction, and atomic force microscopy. The effect of nanostructure and the importance of nanofiller dispersion were analyzed in connection with mechanical and electrical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Optical properties of some new azo photoisomerizable bismaleimide derivatives

Novel polythioetherimides bearing azobenzene moieties were synthesized from azobismaleimides and bis-2-mercaptoethylether. Kinetics of trans-cis photoisomerization and of thermal conversion of cis to trans isomeric forms were investigated in both polymer solution and poly(methyl methacrylate) doped films using electronic absorption spectroscopy. Thermal recovery kinetics is well described by a two-exponential relation both in solution and polymer matrix, while that of low molecular weight azobismaleimide fit a first-order equation. The photoinduced cis-trans isomerization by visible light of azobenzene chromophores was examined in solution and in polymer films. The rate of photoinduced recovery was very high for azobismaleimides.     

One‐Pot Hydroacetylation of Menadione (Vitamin K3) to Menadiol Diacetate (Vitamin K4) by Heterogeneous Catalysis

Vitamin K₄ (menadiol diacetate, MDD) can be easily synthesized through cleaner and more efficient catalytic alternatives following the green chemistry principles. Ionic gold‐based hydroxylated fluorides are active bi‐functional catalysts for the one‐pot hydroacetylation of menadione leading to MDD with 77% selectivity. Unprecedent results were obtained in the presence of oxide‐fluoride catalysts by using a microwave‐assisted hydrogen‐transfer (Meerwein–Ponndorf–Verley reaction) coupled with an acetylation approach, yielding very high selectivities for the target product (95%).     

Fluorine‐18 Radiolabeling and Radiopharmacological Characterization of a Benzodioxolylpyrimidine‐based Radiotracer Targeting the Receptor Tyrosine Kinase EphB4

Members of the Eph receptor tyrosine kinase family play essential roles in the pathogenesis of cancer and are therefore promising candidates for molecular imaging by positron emission tomography (PET), for example. In this regard, radiochemical access to novel PET radiotracers derived from potent inhibitors that target the EphB4 kinase domain and which bear a benzodioxolylpyrimidine structural motif was developed. A synthetic route was established for a new fluorine‐18‐containing radiotracer and for the desired precursor based on a high‐affinity benzodioxolylpyrimidine receptor tyrosine kinase inhibitor lead structure. The radiotracer [¹⁸F] 15 was obtained in 16 % radiochemical yield with a specific activity of ～7 GBq μmol^?1 and >95 % radiochemical purity. Due to the implication of EphB4, particularly in the progression, angiogenesis, and metastasis of melanoma, EphB4‐overexpressing human melanoma cells were generated and used as a novel in vitro model for radiopharmacological evaluation of the radiotracer. We demonstrate that the corresponding non‐radioactive reference compound regained its functionality as an inhibitor for both EphB4 receptor tyrosine kinase and Src kinase. EphB4 was significantly inhibited at compound concentrations >1 μM . Cellular uptake studies with [¹⁸F] 15 revealed substantial uptake in both EphB4‐overexpressing and control cells. Moreover, NMRI nu/nu mice bearing both EphB4‐overexpressing tumors and control tumors were used for radiopharmacological characterization by biodistribution studies ex vivo and by dynamic small‐animal PET experiments in vivo. Despite the high metabolic stability of the novel radiotracer observed in vivo, no substantial binding or accumulation in EphB4‐overexpressing and control tumors was observed. Nevertheless, we point out that the approach presented herein gives convenient access to novel ¹⁸F‐labeled benzodioxolylpyrimidines and is a promising strategy for the further development of novel radiotracers for imaging Eph receptor tyrosine kinases in cancer.