Large-scale production of high-quality multi-walled carbon nanotubes: Role of precursor gas and of Fe-catalyst support

The crucial role of precursor gas (PG) and of catalyst support (CS) in the growth of multi-walled C nanotubes (MWCNTs) by iron-catalysed chemical vapour deposition (CVD) is evidenced. This is accomplished by comparing structural and morphological properties of MWCNTs synthesised by the use of different PGs (ethane and isobutane) and CSs (silica and alumina). The results of analyses, carried out on catalysts and C deposits by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS), thermo-gravimetry (TG) and X-ray diffraction (XRD), demonstrate that Al₂O₃-supported catalysts are more efficient than SiO₂-supported ones in decomposing hydrocarbons. The use of i-C₄H₁₀ as PG allows reducing Fe-encapsulation and improving yield (Y_C) and selectivity, so as the large-scale production (Y_C > 900 wt.%) of high-quality nanotubes can be operated even at moderate reaction temperature (600 °C) after proper calibration of Fe-load (29 wt.%) and catalyst reduction temperature (500 °C).     

GBA Mutations Influence the Release and Pathological Effects of Small Extracellular Vesicles from Fibroblasts of Patients with Parkinson’s Disease

Heterozygous mutations in the GBA gene, encoding the lysosomal enzyme glucocerebrosidase (GCase), are the strongest known genetic risk factor for Parkinson’s disease (PD). The molecular mechanisms underlying the increased PD risk and the variable phenotypes observed in carriers of different GBA mutations are not yet fully elucidated. Extracellular vesicles (EVs) have gained increasing importance in neurodegenerative diseases since they can vehiculate pathological molecules potentially promoting disease propagation. Accumulating evidence showed that perturbations of the endosomal–lysosomal pathway can affect EV release and composition. Here, we investigate the impact of GCase deficiency on EV release and their effect in recipient cells. EVs were purified by ultracentrifugation from the supernatant of fibroblast cell lines derived from PD patients with or without GBA mutations and quantified by nanoparticle tracking analysis. SH-SY5Y cells over-expressing alpha-synuclein (α-syn) were used to assess the ability of patient-derived small EVs to affect α-syn expression. We observed that defective GCase activity promotes the release of EVs, independently of mutation severity. Moreover, small EVs released from PD fibroblasts carrying severe mutations increased the intra-cellular levels of phosphorylated α-syn. In summary, our work shows that the dysregulation of small EV trafficking and alpha-synuclein mishandling may play a role in GBA-associated PD.     

Multivariate Analysis of <Superscript>1</Superscript>H-NMR Spectra of Genetically Characterized Extra Virgin Olive Oils and Growth Soil Correlations

Mono-varietal extra virgin olive oils were micro-extracted from drupes that were selectively collected from 28 trees distributed in five different Southern Italian Apulian areas. Nuclear Magnetic Resonance (NMR) profiles of these oil samples were correlated to the genetic (young green material) and soil (samples collected within the foliage projection) data of the tree of origin. Genetic analysis, performed on the samples using SSRs (Simple Sequence Repeats) by 9 microsatellite loci, confirmed the specific cultivar assignment (among Cima di Mola, Coratina, Ogliarola, and Oliva Rossa cultivars). Chemometric methods applied to ¹H-NMR spectroscopic data were used for cultivar and geographical origin discrimination of the studied extra virgin olive oils. Linear Discriminant Analysis (LDA) afforded a high reliability degree for discriminating cultivars (almost 90% of prediction ability), and a good assigning ability for the geographical origin (Ogliarola and Coratina samples used as subsets). Soil analyses were performed for each tree. Regression analysis was applied to soil composition in order to correlate available nutrients and total metals with the content of fatty acids and minor components present in monovarietal extra virgin olive oils. In the case of oleic and linoleic fatty acids, and for some terpenes, B, Cr, Mn, Zn were found to give significant correlations. Zn and Mn were the most significant trace elements for all the correlations found (p < 0.01). The results obtained (genetic, spectroscopic and soil analyses) are discussed as a multidisciplinary approach for setting up a strategy for a cultivar and/or geographic origin certification committed database construction.     

The interactive effects of irrigation,nitrogen fertilisation rate,delayed harvest and storage on the polyphenol content in red grape (Vitis vinifera) berries: A factorial experimental design

Polyphenol concentrations, including anthocyanidins, flavonols, flavan-3-ols and stilbenes, were quantified by liquid chromatography/mass spectrometry in two cultivars of red grapes for daily consumption, which were subjected to different kinds of water supply and nitrogen fertilisation rates. Samples from the same vineyards were also analysed after a 6 week storage in a refrigerator and 6 week delayed harvesting. Berry skins and seeds were analysed separately.     

Flame acceleration due to turbulence produced by obstacles

This paper reports on an investigation of the influence of obstacles on the propagation of freely expanding cylindrical flames. The flame speed is found to depend critically on the obstacle configuration and flame speeds up to 130 m/sec in stoichiometric methane-air mixtures are readily achieved by placing appropriate turbulence producing obstacles in the flame path. This is ～ 24 times the flame speed observed with no obstacles. The dramatic influence of obstacles is interpreted in terms of the positive feedback coupling between the flame itself and the turbulence and flow field distortions produced by the obstacles. It is also shown that the flame is unable to maintain its large turbulent flame speed without repeated obstacles to provide flow field distortions and turbulence continuously.     

Comparative assessment of genotoxicity of mineral water packed in polyethylene terephthalate (PET) and glass bottles

The potential migration of genotoxic compounds into mineral water stored in polyethylene terephthalate (PET) bottles was evaluated by an integrated chemical/biological approach using short-term toxicity/genotoxicity tests and chemical analysis. Six commercial brands of still and carbonated mineral water bottled in PET and in glass were stored at 40 °C for 10 days in a stove according to the standard EEC total migration test (82/711/EEC), or at room temperature in the dark. After treatment, the samples were analysed using gas-chromatography/mass spectrometry (GC/MS) to detect volatile and non-volatile compounds, the Microtox^® test to evaluate potential toxicity of the samples, and three mutagenicity tests - Tradescantia and Allium cepa micronucleus tests and the Comet assay on human leukocytes - to detect their genotoxic activity.GC/MS analysis did not detect phthalates or acetaldehyde in the water samples. The Microtox^® test found no toxic effects. Mutagenicity tests detected genotoxic properties of some samples in both PET and glass bottles. Statistical analyses showed a positive association between mineral content and mutagenicity (micronuclei in A. cepa and DNA damage in human leukocytes). No clear effect of treatment and PET bottle was found. These results suggest the absence of toxic compounds migrating from PET regardless of time and conditions of storage. In conclusion, bottle material and stove treatment were not associated with the genotoxic properties of the water; the genotoxic effects detected in bottled water may be related to the characteristics of the water (minerals and CO₂ content).     

Nanofilled polyols for viscoelastic polyurethane foams

The use of polyether polyols is common in polyurethane industry, particularly in soft PU applications. In particular, viscoelastic foams, characterized by slow recovery after compression, are obtained using poly(ethylene oxide) (PEO) polyols. Nanofilled polyols can be used for the production of viscoelastic foams with improved fire resistance properties. The high polarity of polyether polyols is responsible of a poor affinity with the organic modifiers used in commercial organically modified montmorillonite (omMMT). In this work, organically modified montmorillonites were prepared, having an improved affinity with the polyether polyols used for the production of soft PU foams. The montmorillonite was modified by using polyetheramines with different ethyleneoxide/propyleneoxide amounts. A strongly intercalated/exfoliated structure was obtained after mixing the polyol with the omMMT. The viscosity increased by three orders of magnitude and the diffraction angles of the MMT measured by x‐ray analysis decreased to values lower than 1.5°. The intercalated structure was preserved after the curing stage, when the isocyanate was added to the polyol/omMMT. The resulting polyurethane had an irregular open cell structure, and was characterized by a mechanical properties comparable to those of unfilled polyurethane. Copyright © 2009 Society of Chemical Industry     

Homoepitaxial CVD diamond: Raman and time-resolved PL characterization

In this work, we report on the structural characterization of homoepitaxial Microwave Plasma Enhanced CVD diamond grown onto Ib diamond substrates by varying systematically the methane to hydrogen ratio in the gas mixture (1–7% CH₄). X-ray diffraction, Raman spectroscopy and photoluminescence (PL) have been used to characterize the diamond samples. Raman measurements pointed out the excellent crystalline quality and phase purity of the specimens. PL measurements in the 1.7–2.7 eV energy range have shown completely flat spectra, excluding the presence of nitrogen-related optical centers. Such results show that the homoepitaxial CVD diamond can be grown, at moderate microwave power (720 W), and at growth rates not too low ( 1 μm/h) preserving a good quality. Moreover, the homoepitaxial crystals exhibited a strong free-exciton recombination radiation at room temperature even at the highest methane concentration used (7%). Preliminary measurements of the lifetime of the free exciton at room temperature have been also performed. The excitation was produced by a 5 ns pulsed laser irradiation at energies above the diamond band gap. The results have been compared with the structural properties of the samples and correlated with the growth conditions.