Cathodoluminescence characterization of β-SiC nanowires and surface-related silicon dioxide

The main goal of our study is to prepare and to understand the properties of cubic SiC nanowires (NWs) and to characterize its native silicon dioxide. The wires, with diameters ranging from 10 nm to 2 μm, have been prepared by a CVD process on Si (0 0 1) substrates, using CO as the carbon source and Ni as the catalyst. A structural and optical analysis, by means of TEM, micro-Raman and cathodoluminescence (CL) spectroscopy, has been performed. Two sets of samples have been studied, labelled A and B, which differ for growth process conditions. Set A showed two broad CL peaks. Set B showed a much weaker CL emission. This difference has been explained by means of TEM investigation and micro-Raman spectra: set A shows a thick amorphous silicon dioxide layer on the wire surface, whereas set B shows a thin or absent oxide layer. Consequently, the nature of the CL emission has to be ascribed mainly to oxide-related recombination.     

Differential scanning calorimetry thermal properties and oxidative stability indices of microwave heated extra virgin olive oils

BACKGROUND: The use of differential scanning calorimetry (DSC) for assessing the deterioration effect of microwave heating on vegetable oils, and on olive oils in particular, has been partially explored in literature. The aim of this work was to evaluate the potential of DSC to discriminate among microwaved extra virgin olive oils (EvOo from different olive cultivar and origin), according to changes on thermal properties (upon cooling and heating) and traditional oxidative stability indices (peroxide, p‐anisidine and TOTOX values). RESULTS: An elevated value of lipid oxidation was reached by the most unsaturated EvOo sample (9.5% of linoleic acid) at 6 min of microwave treatment. Free acidity significantly increased (0.42%) only for the oil sample with the highest water content (874 mg kg^?1 oil) at the longest time of treatment. Crystallisation enthalpies significantly decreased and the major exothermic peak shifted towards lower temperature, leading to enlargement of the transition range in all samples due to the formation of weak and mixed crystals among triacylglycerols and lipid degradation products. On the contrary, thermal properties upon heating appeared to similarly vary among samples. CONCLUSIONS: The analysis of DSC thermal properties upon cooling seemed to clearly discriminate among different EvOo samples after microwaving. The relation between changes of thermal properties and oxidation parameters should be further studied using additional oxidative stability indices on a larger set of oil samples, due to the complexity of EvOo composition. Copyright © 2010 Society of Chemical Industry     

Photoprotective Role of Photosynthetic and Non-Photosynthetic Pigments in Phillyrea latifolia: Is Their “Antioxidant” Function Prominent in Leaves Exposed to Severe Summer Drought?

Carotenoids and phenylpropanoids play a dual role of limiting and countering photooxidative stress. We hypothesize that their “antioxidant” function is prominent in plants exposed to summer drought, when climatic conditions exacerbate the light stress. To test this, we conducted a field study on Phillyrea latifolia, a Mediterranean evergreen shrub, carrying out daily physiological and biochemical analyses in spring and summer. We also investigated the functional role of the major phenylpropanoids in different leaf tissues. Summer leaves underwent the most severe drought stress concomitantly with a reduction in radiation use efficiency upon being exposed to intense photooxidative stress, particularly during the central hours of the day. In parallel, a significant daily variation in both carotenoids and phenylpropanoids was observed. Our data suggest that the morning-to-midday increase in zeaxanthin derived from the hydroxylation of ß-carotene to sustain non-photochemical quenching and limit lipid peroxidation in thylakoid membranes. We observed substantial spring-to-summer and morning-to-midday increases in quercetin and luteolin derivatives, mostly in the leaf mesophyll. These findings highlight their importance as antioxidants, countering the drought-induced photooxidative stress. We concluded that seasonal and daily changes in photosynthetic and non-photosynthetic pigments may allow P. latifolia leaves to avoid irreversible photodamage and to cope successfully with the Mediterranean harsh climate.     

Stochastic and recursive estimation of the hygro-thermo-chemical-mechanical parameters of concrete through Monte Carlo analysis and extended Kalman filter

Structural and Multidisciplinary Optimization - Hygro-thermo-chemical-mechanical models, used to determine the variations over time of temperature, relative humidity and shrinkage induced...     

Emergence of collective changes in travel direction of starling flocks from individual birds' fluctuations

One of the most impressive features of moving animal groups is their ability to perform sudden coherent changes in travel direction. While this collective decision can be a response to an external alarm cue, directional switching can also emerge from the intrinsic fluctuations in individual behaviour. However, the cause and the mechanism by which such collective changes of direction occur are not fully understood yet. Here, we present an experimental study of spontaneous collective turns in natural flocks of starlings. We employ a recently developed tracking algorithm to reconstruct three-dimensional trajectories of each individual bird in the flock for the whole duration of a turning event. Our approach enables us to analyse changes in the individual behaviour of every group member and reveal the emergent dynamics of turning. We show that spontaneous turns start from individuals located at the elongated tips of the flocks, and then propagate through the group. We find that birds on the tips deviate from the mean direction of motion much more frequently than other individuals, indicating that persistent localized fluctuations are the crucial ingredient for triggering a collective directional change. Finally, we quantitatively verify that birds follow equal-radius paths during turning, the effects of which are a change of the flock''s orientation and a redistribution of individual locations in the group.     

Graphene nanoplatelets composite membranes for thermal comfort enhancement in performance textiles

The advent of 2D nanostructured materials as advanced fillers for polymer matrix composites has opened the doors to a plethora of new industrial applications requiring both electric and thermal management. Unique properties, in fact, can arise from accurate selection and processing of 2D fillers and their matrix. Here, we report an innovative family of nanocomposite membranes based on polyurethane (PU) and graphene nanoplatelets (GNPs), designed to improve thermal comfort in functional textiles. GNP particles were thoroughly characterized (through Raman, atomic force microscopy, high-resolution TEM, scanning electron microscope), and showed high crystallinity (I_D/I_G = 0.127), low thickness (D50 < 6–8 layers), and high lateral dimensions (D50 ≈ 3 μm). When GNPs were loaded (up to 10% wt/wt) into the PU matrix, their homogeneous dispersion resulted in an increase of the in-plane thermal conductivity of composite membranes up to 471%. The thermal dissipation of membranes, alone or coupled with cotton fabric, was further evaluated by means of an ad hoc system designed to simulate a human forearm. The results obtained provide a new strategy for the preparation of membranes suitable for technical textiles, with improved thermal comfort.     

Serenoa repens and Urtica dioica Fixed Combination: In-Vitro Validation of a Therapy for Benign Prostatic Hyperplasia (BPH)

Benign prostatic hyperplasia (BPH) is an age-related chronic disorder, characterized by the hyperproliferation of prostatic epithelial and stromal cells, which drives prostate enlargement. Since BPH aetiology and progression have been associated with the persistence of an inflammatory stimulus, induced both by Nuclear Factor-kappa B (NF-κB) activation and reactive oxygen species (ROS) production, the inhibition of these pathways could result in a good tool for its clinical treatment. This study aimed to evaluate the antioxidant and anti-inflammatory activity of a combined formulation of Serenoa repens and Urtica dioica (SR/UD) in an in vitro human model of BPH. The results confirmed both the antioxidant and the anti-inflammatory effects of SR/UD. In fact, SR/UD simultaneously reduced ROS production, NF-κB translocation inside the nucleus, and, consequently, interleukin 6 (IL-6) and interleukin 8 (IL-8) production. Furthermore, the effect of SR/UD was also tested in a human androgen-independent prostate cell model, PC3. SR/UD did not show any significant antioxidant and anti-inflammatory effect, but was able to reduce NF-κB translocation. Taken together, these results suggested a promising role of SR/UD in BPH and BPH-linked disorder prevention.     

Advance on processing of compostable and thermally stable biodegradable polyester blends

Flexible and semiflexible packagings can be manufactured by cast extrusion of plastic sheet and thermoforming of containers. Thermal stability is often required as packaging items after being thermoformed can come in contact with hot food/beverage, especially during hot filling operations. In this framework, the present study deals with the design and manufacturing by thermoforming of plastic containers that are, at the same time, compostable and suitable for high-temperature applications (~100 °C). First, extrusion compounding of Poly(l -lactic acid) (PLLA)-based biodegradable polyester blends was performed. In particular, the effect on the material properties of different types of nucleating agents was investigated. Combinations of micro-lamellar talc, poly(d -lactic acid) (PDLA), ethylene bisstearamide (EBS), and titanium dioxide (TiO₂) were studied. The formulations involving EBS boast the highest crystallinity and the fastest onset of the crystalline phase on sheets produced by cast extrusion. Conversely, the formulations involving TiO₂ feature the lowest degree of crystallinity and the slowest onset of the crystalline phase. Combinations of talc and PDLA exhibit an intermediate behavior. Second, thermoforming of the plastic foils was performed. A very different trend of the crystallization after thermoforming is shown. Indeed, crystallinity is the highest for the formulations involving talc and PDLA, the lowest for the ones containing EBS. In conclusion, the biodegradable polyester blends are found to be suitable for the manufacturing of compostable and thermostable packaging items by cast extrusion and thermoforming. Final crystallization of the material and the resulting thermal stability can be fine-tuned by modulating type and amount of nucleating agents. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48722.     

Nanomotion Detection Method for Testing Antibiotic Resistance and Susceptibility of Slow‐Growing Bacteria

Infectious diseases are caused by pathogenic microorganisms and are often severe. Time to fully characterize an infectious agent after sampling and to find the right antibiotic and dose are important factors in the overall success of a patient's treatment. Previous results suggest that a nanomotion detection method could be a convenient tool for reducing antibiotic sensitivity characterization time to several hours. Here, the application of the method for slow‐growing bacteria is demonstrated, taking Bordetella pertussis strains as a model. A low‐cost nanomotion device is able to characterize B. pertussis sensitivity against specific antibiotics within several hours, instead of days, as it is still the case with conventional growth‐based techniques. It can discriminate between resistant and susceptible B. pertussis strains, based on the changes of the sensor's signal before and after the antibiotic addition. Furthermore, minimum inhibitory and bactericidal concentrations of clinically applied antibiotics are compared using both techniques and the suggested similarity is discussed.