Dust tracking techniques applied to the STARDUST facility: First results

An important issue related to future nuclear fusion reactors fueled with deuterium and tritium is the creation of large amounts of dust due to several mechanisms (disruptions, ELMs and VDEs). The dust size expected in nuclear fusion experiments (such as ITER) is in the order of microns (between 0.1 and 1000 μm). Almost the total amount of this dust remains in the vacuum vessel (VV). This radiological dust can re-suspend in case of LOVA (loss of vacuum accident) and these phenomena can cause explosions and serious damages to the health of the operators and to the integrity of the device. The authors have developed a facility, STARDUST, in order to reproduce the thermo fluid-dynamic conditions comparable to those expected inside the VV of the next generation of experiments such as ITER in case of LOVA. The dust used inside the STARDUST facility presents particle sizes and physical characteristics comparable with those that created inside the VV of nuclear fusion experiments. In this facility an experimental campaign has been conducted with the purpose of tracking the dust re-suspended at low pressurization rates (comparable to those expected in case of LOVA in ITER and suggested by the General Safety and Security Report ITER-GSSR) using a fast camera with a frame rate from 1000 to 10,000 images per second. The velocity fields of the mobilized dust are derived from the imaging of a two-dimensional slice of the flow illuminated by optically adapted laser beam. The aim of this work is to demonstrate the possibility of dust tracking by means of image processing with the objective of determining the velocity field values of dust re-suspended during a LOVA

Zinc Polyaleuritate Ionomer Coatings as a Sustainable, Alternative Technology for Bisphenol A-Free Metal Packaging

Sustainable coatings for metal food packaging were prepared from ZnO nanoparticles (obtained by the thermal decomposition of zinc acetate) and a naturally occurring polyhydroxylated fatty acid named aleuritic (or 9,10,16-trihydroxyhexadecanoic) acid. Both components reacted, originating under specific conditions zinc polyaleuritate ionomers. The polymerization of aleuritic acid into polyaleuritate by a solvent-free, melt polycondensation reaction was investigated at different times (15, 30, 45, and 60 min), temperatures (140, 160, 180, and 200 °C), and proportions of zinc oxide and aleuritic acid (0:100, 5:95, 10:90, and 50:50, w/w). Kinetic rate constants calculated by infrared spectroscopy decreased with the amount of Zn due to the consumption of reactive carboxyl groups, while the activation energy of the polymerization decreased as a consequence of the catalyst effect of the metal. The adhesion and hardness of coatings were determined from scratch tests, obtaining values similar to robust polymers with high adherence. Water contact angles were typical of hydrophobic materials with values ≥94°. Both mechanical properties and wettability were better than those of bisphenol A (BPA)-based resins and most likely are related to the low migration values determined using a hydrophilic food simulant. The presence of zinc provided a certain degree of antibacterial properties. The performance of the coatings against corrosion was studied by electrochemical impedance spectroscopy at different immersion times in an aqueous solution of NaCl. Considering the features of these biobased lacquers, they can be potential materials for bisphenol A-free metal packagingPeer reviewe

Interplay between transglutaminases and heparan sulphate in progressive renal scarring

Transglutaminase-2 (TG2) is a new anti-fibrotic target for chronic kidney disease, for its role in altering the extracellular homeostatic balance leading to excessive build-up of matrix in kidney. However, there is no confirmation that TG2 is the only transglutaminase involved, neither there are strategies to control its action specifically over that of the conserved family-members. In this study, we have profiled transglutaminase isozymes in the rat subtotal nephrectomy (SNx) model of progressive renal scarring. All transglutaminases increased post-SNx peaking at loss of renal function but TG2 was the predominant enzyme. Upon SNx, extracellular TG2 deposited in the tubulointerstitium and peri-glomerulus via binding to heparan sulphate (HS) chains of proteoglycans and co-associated with syndecan-4. Extracellular TG2 was sufficient to activate transforming growth factor-β1 in tubular epithelial cells, and this process occurred in a HS-dependent way, in keeping with TG2-affinity for HS. Analysis of heparin binding of the main transglutaminases revealed that although the interaction between TG1 and HS is strong, the conformational heparin binding site of TG2 is not conserved, suggesting that TG2 has a unique interaction with HS within the family. Our data provides a rationale for a novel anti-fibrotic strategy specifically targeting the conformation-dependent TG2-epitope interacting with HS

Room Temperature Fabrication of Silicon Nanocrystals by Pulsed Laser Deposition

In this work a room temperature single-step physical vapour deposition process is presented for the fabrication of nanosized Si crystals (diameter below 10 nm) embedded in an amorphous matrix, together with unique novel nanostructures consisting of silicon amorphous-crystalline core-shell nanostructures. Pulsed laser deposition in a background atmosphere (Ar or a mixture of < 3 vol. % of H2 in Ar) is used to induce cluster nucleation in the gas phase and to vary the deposition kinetic energy, in order to grow Si films of different morphology and porosity, at the nanoscale, as a function of gas pressure. Relatively high-pressure processing (100 Pa) leads to a hierarchically nanostructured film composed of Si nanocrystals embedded in a columnar porous amorphous matrix, as assessed by high resolution transmission electron microscopy. Raman spectroscopy analysis shows quantum-confinementinduced shift of the Si peak at 520 cm-1, thus confirming the occurrence of nanocrystals. Finally, in-situ silicon oxidation has been effectively shown to be decreased after adaptation of a mixture of few-percent-hydrogen in argon as background gas

The mechanism of dysbiosis in alcoholic liver disease leading to liver cancer

Currently, alcoholic liver disease (ALD) is one of the most prevalent chronic liver diseases worldwide, representing one of the main etiologies of cirrhosis and hepatocellular carcinoma (HCC). Although we do not know the exact mechanisms by which only a selected group of patients with ALD progress to the final stage of HCC, the role of the gut microbiota within the progression to HCC has been intensively studied in recent years. To date, we know that alcohol-induced gut dysbiosis is an important feature of ALD with important repercussions on the severity of this disease. In essence, an increased metabolism of ethanol in the gut induced by an excessive alcohol consumption promotes gut dysfunction and bacterial overgrowth, setting a leaky gut. This causes the translocation of bacteria, endotoxins, and ethanol metabolites across the enterohepatic circulation reaching the liver, where the recognition of the pathogen-associated molecular patterns via specific Toll-like receptors of liver cells will induce the activation of the nuclear factor kappa-B pathway, which releases pro-inflammatory cytokines and chemokines. In addition, the mitogenic activity of hepatocytes will be promoted and cellular apoptosis will be inhibited, resulting in the development of HCC. In this context, it is not surprising that microbiota-regulating drugs have proven effectiveness in prolonging the overall survival of patients with HCC, making attractive the implementation of these drugs as co-adjuvant for HCC treatment

Studio morfologico di nanostrutture di layered double hydroxides (LDH) depositate su film sottili di alluminio

We have synthesized nanoplatelets of crystalline (Zn,Al) Layered Double Hydroxide (LDH) by a single-step and room temperature hydrothermal process on aluminum thin layers sputtered on different substrates. The structure, morphology, dimensions and compositions of nanoplatelets have been investigated by Scanning Electron Microscopy (SEM), X-Rays diffraction (XRD), Energy Dispersion Spectroscopy (EDS) and Photoluminescence (PL). Different behaviours of the thickness of nanoplatelets have been obtained by varying the most important growth parameters (thickness of Al coatings, growth temperature and duration). The thickness of the observed nanoplatelets results to be clearly dependent on the aluminun content available in the coating. On the contrary, the stoichiometry and the Zn/Al ratio does not change appreciably. Furthermore, for the thinnest aluminum layer, the LDH nanostructures result to be not well-shaped, and the excess zinc, on the one hand does not cause changes in the composition, on the other hand has as a consequence the formation of insulated ZnO nanorods. These samples show the defect-related visible luminescence, approximately centered at 600nm, and due to the nanorods presence, while no significant luminescence was expected from LDH nanosheets. Results obtained show that a controlled and spatially localized synthesis of Zn/Al LDH nanoplatelets can be obtained even on substrates having large surface area provided that the sputtered aluminum coating results to be thicker than 10nm, thus making possible the integration of these nanostructures on substrates of different nature

Wurtzite nanowires strain control by DC electrical stimulation

Nanomechanics is a highly developed area of research, given the significant reported changes in material properties at the nanometer scale, requiring the development of new theories to explain the underlying mechanisms. Such theories must be based on measurements that are as accurate as possible, but unfortunately, conventional experimental techniques do not apply to such small components. Here we present a unique new method to control electro-mechanical forces on quasi −1D nanostructures through static electric fields with multiple ways of control of GaAs nanowires’ strain directly on the growth substrate

Ga metal nanoparticle-GaAs quantum molecule complexes for Terahertz generation

A hybrid metal-semiconductor nanosystem for the generation of THz radiation, based on the fabrication of GaAs quantum molecules-Ga metal nanoparticles complexes through a self assembly approach, is proposed. The role of the growth parameters, the substrate temperature, the Ga and As flux during the quantum dot molecule fabrication and the metal nanoparticle alignment is discussed. The tuning of the relative positioning of quantum dot molecules and metal nanoparticles is obtained through the careful control of Ga droplet nucleation sites via Ga surface diffusion. The electronic structure of a typical quantum dot molecule was evaluated on the base of the morphological characterizations performed by Atomic Force Microscopy and cross sectional Scanning Electron Microscopy, and the predicted results confirmed by micro-photoluminescence experiments, showing that the Ga metal nanoparticle-GaAs quantum molecule complexes are suitable for terahertz generation from intraband transition.

Insecticidal activity of strains of <i>Bacillus thuringiensis</i> on larvae and adults of <i>Bactrocera oleae</i> Gmelin (Dipt. Tephritidae)

The olive fly, Bactrocera oleae, is the key pest on olives in the Mediterranean area. The pest can destroy, in some cases, up to 70% of the olive production. Its control relies mainly on chemical treatments, sometimes applied by aircraft over vast areas, with their subsequent ecological and toxicological side effects. Bacillus thuringiensis is a spore-forming soil bacterium which produces a protein crystal toxic to some insects, including the orders of Lepidoptera, Diptera, and Coleoptera and other invertebrates. The aim of this study was to search for isolates toxic to B. oleae. Several hundred B. thuringiensis isolates were obtained from olive groves and olive presses in different areas of Greece, Sardinia (Italy), and Spain and from cooperating scientists throughout the world. Some isolates were found toxic only to adults or larvae and some to both stages of the olive fly. In addition, the most toxic isolates were assayed on Opius concolor Szepl. (Hym. Braconidae), the most important parasitoid of the olive fruit fly. Only 3 isolates out of 14 gave significant mortality against this parasitoid. Several of the most toxic crystalliferous isolates may contain novel toxins since they gave no PCR products when probed with primers specified for 39 known toxin genes