Selective Aryl α‐Diimine/Palladium‐Catalyzed Bis‐Alkoxy‐ carbonylation of Olefins for the Synthesis of Substituted Succinic Diesters

Aryl α‐diimine derivatives have been used, for the first time, as efficient new ligands for the palladium‐catalyzed oxidative bis‐alkoxycarbonylation reaction of olefins. The most active catalyst was formed in situ from bis(9‐anthryl)‐2,3‐dimethyl‐1,4‐diazabutadiene and palladium(II) trifluoroacetate [Pd(TFA)₂]. This catalytic system was able to selectively convert olefins into succinic diesters in good yields (up to 97%) and low catalyst loading (up to 0.5 mol%) under mild reaction conditions [4 bar of carbon monoxide (CO) at 20 °C in the presence of p‐toluenesulphonic acid as additive and p‐benzoquinone as oxidant]. The optimized conditions could be successfully applied to both aromatic and aliphatic olefins, by using methanol, benzyl alcohol or isopropyl alcohol as nucleophiles.

     

Extraction of metals from automotive shredder residue:Preliminary results of different leaching systems

The study is focused on the extraction of valuable metals from automotive shredder residue (ASR) by different leaching solutions. First, ASR samples were roasted at 600 °C to simulate a thermal treatme...     

Modulation of CD14 and TLR4⋅MD‐2 Activities by a Synthetic Lipid A Mimetic

Monosaccharide lipid A mimetics based on a glucosamine core linked to two fatty acid chains and bearing one or two phosphate groups have been synthesized. Compounds 1 and 2 , each with one phosphate group, were practically inactive in inhibiting LPS‐induced TLR4 signaling and cytokine production in HEK‐blue cells and murine macrophages, but compound 3 , with two phosphate groups, was found to be active in efficiently inhibiting TLR4 signal in both cell types. The direct interaction between compound 3 and the MD‐2 coreceptor was investigated by NMR spectroscopy and molecular modeling/docking analysis. This compound also interacts directly with the CD14 receptor, stimulating its internalization by endocytosis. Experiments on macrophages show that the effect on CD14 reinforces the activity on MD‐2 ? TLR4 because compound 3 's activity is higher when CD14 is important for TLR4 signaling (i.e., at low LPS concentration). The dual targeting of MD‐2 and CD14, accompanied by good solubility in water and lack of toxicity, suggests the use of monosaccharide 3 as a lead compound for the development of drugs directed against TLR4related syndromes.     

PET Radiotracers for Imaging P‐glycoprotein: The Challenge for Early Diagnosis in AD

PET radiotracer development to target in vivo P‐glycoprotein (P‐gp) could be an important strategy for the early diagnosis of neurodegenerative disorders such as Alzheimer’s disease (AD). Indeed, as a dysfunction of P‐gp is responsible for the accumulation of β‐amyloid plaques (a hallmark of AD) in brain parenchyma, P‐gp is the cause of AD onset. P‐gp substrates and inhibitors are useful for imaging the activity or expression of this protein, respectively; herein we discuss the in vivo evaluation of some ¹¹C radiotracers with P‐gp‐inhibitory activity, such as [¹¹C]MC18 and [¹¹C]MC113, as well as P‐gp substrates [¹¹C]MC266 and [¹¹C]MC80. Moreover, the radiosynthesis of all these P‐gp probes is reported.     

Novel HDPE/ground tyre rubber composite materials obtained through in‐situ polymerization and polymerization filling technique

Novel hybrid materials composed by a high density polyethylene (HDPE) matrix and powdered rubber coming from scrap tyres (ground tyre rubber [GTR]) were prepared. Two methods were followed: ethylene was polymerized by a metallocene catalyst (Cp₂ZrCl₂/methylaluminoxane) in the presence of a toluene dispersion of the filler (in‐situ polymerization); and the ethylene was polymerized out after supporting the aluminum‐based co‐catalyst onto the rubber particles surface (polymerization filling technique). The experimental conditions were varied in order to achieve the best catalyst productivity. All the synthesized composites were characterized in order to investigate the occurrence and the extent of interactions between HDPE macromolecular chains and the GTR components and their effects onto the final properties, by comparison with a composite where GTR was included into the matrix through blending in the melt. Scanning electron microscopy, atomic force microscopy, and solvent extractions were performed to this aim. The amount of thermoplastic matrix bonded to the filler was determined, and the extracted polymer was characterized by size exclusion chromatography and differential scanning calorimetry. Finally, stress–strain behavior of the composites obtained, respectively, by catalytic polymerization and melt mixing was compared. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40313.     

Experimental results of nanofluids flow effects on metal surfaces

The results of an experimental study on the effects of the flow of nanofluids (water-based suspensions of nanometer-sized solid particles) on metal surfaces are presented. Either different nanofluids (containing TiO₂, Al₂O₃, ZrO₂, and SiC, respectively) and different target materials (aluminum, copper, stainless steel) have been investigated, under similar operating conditions. Different behaviors were observed depending on the specific combination nanofluid-target material, which in some cases led to severe damaging of the tested target, thus highlighting the need for an adequate preliminary investigation of the possible interactions between the selected nanofluid and the apparatus materials, before its adoption as heat transfer fluid.     

Bioaccessible selenium in Italian agricultural soils: Comparison of the biogeochemical approach with a regression model based on geochemical and pedoclimatic variables

Biogeochemical mapping of selenium in Italian agricultural soils was accomplished by measuring the Se concentration of representative samples of wheat grains from 71 provinces. The range of the concentration values averaged on a provincial basis was 7-245 ng Se g(-1). A multiple regression model based on six geochemical and pedoclimatic variables was developed to interpret the observed data and to predict Se concentration of wheat in areas where analytical data were missing and in the different Italian soil regions. The statistical model explained only part of the observed variance, but succeeded in identifying Se-enriched as well as Se-depleted areas with an acceptable level of agreement with the biogeochemical map based on measured Se in wheat. Furthermore, the model showed that within the range of concentrations measured in Italian soils, Se-bioaccessibility is controlled not only by the Se content of the soil parent rocks, but also by their overall geochemical nature (carbonatic vs. silicatic) and by pedoclimatic variables (temperature and rain intensity excursions) related to fluctuations of soil moisture and pH. Overall, several Se-marginal and Se-deficient areas were identified on the Italian territory. The implications of these findings for public health are discussed briefly.