170,319 research outputs found
Corrigendum to “Tribochemistry of graphene on iron and its possible role in lubrication of steel” [Carbon 106 (2016) 118–124](S0008622316303797)(10.1016/j.carbon.2016.05.025)
No full textThe authors wish to update the reference to a “forthcoming article” in the sentence at page 122: “The difference between the maximum and minimum heights of the [Formula presented] peaks is proportional to the potential corrugation, ΔWsep. As we describe in a forthcoming article, these two properties have general validity, i.e. they hold true in different materials” with the reference to the now published paper: M. Wolloch, G. Levita, P. Restuccia, M. C. Righi, Interfacial charge density and its connection to adhesion and frictional forces, Phys. Rev. Lett. 121 (2018) 026804
Giant subcortical high-frequency SEPs in idiopathic generalized epilepsy: A protective mechanism against seizures?
No full textobjective: recently, we found that high-frequency somatosensory evoked potentials (HF-SEPs), which are modulated by arousal-related structures, were abnormally enhanced during N-REM sleep in two seizure-free IGE patients [restuccia d, rubino m, valeriani m, della marca g. increase of brainstem high-frequency SEP subcomponents during light sleep in seizure-free epileptic patients. clin neurophysiol 2005; 116: 1774-1778]. Here, we aimed at verifying whether similar HF-SEP abnormalities were significantly correlated to the clinical outcome in a larger population of untreated IGE patients. methods: patients were classified as juvenile myoclonic epilepsy (JME; six patients) and childhood or juvenile absence epilepsy (CAE and JAE, six patients). they were untreated because newly diagnosed, or because seizure-free. HF-SEPs from patients were compared with those obtained from 21 healthy volunteers. results: HF-SEPs were abnormally enhanced in all seizure-free CAE-JAE patients, whereas they were normal in all JME patients and in CAE-JAE patients with frequent seizures. not only scalp distribution, but also dipolar source analysis suggested a subcortical origin for these enhanced subcomponents, possibly in the brainstem. conclusions: the enhancement of HF-SEPs might reflect the hyperactivity of arousal-related brainstem structures; such an enhancement was found in all seizure-free CAE-JAE patients, while it was never observed in JME patients. significance: we speculate that the hyperactivity of arousal-related brainstem structures might account for the different clinical outcome among IGE subsyndromes. (c) 2006 international federation of clinical neurophysiology
Mortar Made of Recycled Sand from C&D
No full textAbstractInthe production of coarse recycled aggregates (RA), the fine fraction is involuntarily produced, representing a large amount of the weight of the crushed C&D waste. In this work the mortar has been analyzed, by replacing standardized sand (SS) with recycled sand (RS) and by using a fixed w/c ratio equal to 0,5. The most relevant problem has been occurred during the mixing phase: in fact, RS induced a high water demand which made the mechanical properties worst. The results show that, by adding the optimum dose of superplasticizer, the RS mortars have the same mechanical characteristics of the SS mortar
Influence of pyrolysis parameters on the efficiency of the biochar as nanoparticles into cement-based composites
No full textIn this research, a particular kind of biochar provided by UK Biochar Centre has been added as nanoparticles into cementitious composites. Its principle characteristic lies in the standardization of its process production, that makes it suitable to been used as filler in cement-matrix composites, ensuring the reproducibility of the cement mix (I. Cosentino "The use of Bio-char for sustainable and durable concrete", 2017). The pyrolysis parameters and the content of carbon in the standardized biochar influenced its efficiency to enhance the mechanical properties of the cement composites: the results, in terms of flexural strength and fracture energy, have been worse than those obtained in previous studies (L. Restuccia "Re-think, Re-use: agro-food and C&D waste for high-performance sustainable cementitious composites", 2016), in which particles have been produced with higher temperature. However, also with standardized biochar a general enhancement of mechanical properties has been recorded, a sign that they can be used to create new green building materials. (C) 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers
Cryotolerant Saccharomyces strains and spoilage of refrigerated musts
No full textThis study regards yeasts isolated from refrigerated musts with patent ongoing fermentation. The isolates belonged to the genus Saccharomyces sensu stricto with an optimal growth temperature less than 30 degrees C. Karyotype analysis highlighted the constant presence of two well-defined trait bands in the low molecular weight between 225 and 375 kb that distinguished them unequivocally from normal Saccharomyces cerevisiae strains. The isolated strains individually reinoculated in sterile must at 25 degrees C, produce complete fermentation. Analysis of minor fermentation compounds revealed other differences between these strains and Saccharomyces cerevisiae strains. These strains are responsible for the spoilage of fermenting refrigerated must. Phenotype traits, combined with karyotype, suggest that they should not be assigned to Saccharomyces cerevisiae but more reasonably to Saccharomyces bayanus uvarum type
Identification of Pichia anomala isolated from yoghurt by RFLP of the ITS region
No full textSeveral packs of swollen retailed plain and flavoured yoghurt were examined. The most commonly found species was Pichia anomala, identified both by physiological tests and RFLP analysis of the rDNA internal transcribed spacer (ITS) region. The isolated strains did not ferment lactose and were positive for galactose fermentation, confirming the hypothesis that galactose-fermenting yeast could be the cause of spoilage in yoghurt. (C) 2001 Elsevier Science B.V. All rights reserved
Re-think, Re-use: agro-food and C&D waste for high-performance sustainable cementitious composites
No full textWith the development of "mega-constructions" and especially of slender components in ever-higher buildings, new construction materials need to be more performing. At the same time, environmental problems emerged during the last decades require that the manufacturing process of traditional building material needs to be more efficient and environmentally sustainable. The question behind this research is "You can get a traditional building material with better performance and less energy consumption?" Concrete is the most artificial material produced and used in the world. In recent years, the production of cement has reached 4 billion tons, making it a process with a high-energy consumption: it is one of the main causes of the production and placing of CO2 in the atmosphere. With the increasing demand for high-performance building materials, today we are witnessing a very common phenomenon: improve the mechanical properties (compressive and flexural strength, toughness and durability are becoming increasingly important features in the new concrete technology) by aggregates and very expensive additives. An example of this is certainly the direction of the predominant research in America, which involves the use of carbon-based materials such as Carbon Nanotubes (CNTs) to meet the market needs of the new concrete. Through a simple reflection ("Concrete is a low cost material, why improve it with materials that, albeit in very small quantities, greatly affect it with their prohibitive cost?") was thus thought to use "poor" carbon-based materials. Therefore, the main theme of the present research is to obtain an enhancement of strength and toughness in traditional cement based materials by incorporating waste materials, to meet the challenge of "green" construction material
Monitoring water and oxygen splitting at graphene edges and folds: Insights into the lubricity of graphitic materials
No full textThe functionality of graphene as lubricant material is affected by extrinsic factors, such as the film thickness and the environmental conditions. Graphite lubricating capability depends as well on air humidity. To accurately describe the tribochemistry mechanisms underlying these behaviours we adopt a Quantum Mechanics/Molecular Mechanics approach. We show that reactive edges are able to cause a huge friction increase, which is quantified for graphene flakes between sliding diamond surfaces. Moreover, folds spontaneously formed in single layer graphene under tribological conditions are shown to be highly reactive due to carbon re-hybridization. This observation offers a new hint for interpreting the dependence of graphene friction on the number of layers. Both water and oxygen molecules are found to be effective in quenching the reactivity of defects by dissociative chemisorption. However, peculiar mechanisms of water molecules makes humidity more effective than oxygen for enabling the lubricity of graphitic media. They include collective processes as Grotthus-like proton diffusion enhanced by confinement, and the strong change in hydrophilic character of the passivated media. This comprehensive study sheds a new light on debated issues of graphene and graphite tribology, and highlights the potentiality of these materials for metal-free catalysis, e.g., for H production by water splitting
Phosphorus Adsorption on Fe(110): An ab Initio Comparative Study of Iron Passivation by Different Adsorbates
No full textFrom corrosion protection to embrittlement and lubrication, the presence of phosphorus at iron surfaces is critical for a range of processes and applications. However, phosphorus adsorption on iron has never been studied experimentally or theoretically. Here P chemisorption on the most stable surface of iron is analyzed by means of density functional theory. The most stable adsorption geometry and coverage are identified, and the changes induced by P adsorption on the structural and electronic properties of the metal are discussed. A systematic comparison among P, S, N, and O uncovers a peculiar behavior of the P and S species: attractive adatom-adatom interactions at high coverage lead to the formation of two-dimensional overlayers that reduce the metal reactivity and work function. This effect is important in iron embrittlement and for the functionality of P- and S-containing additives included in lubricant oils
Empirical fragility curves for masonry buildings struck by the 2016 Central Italy earthquake
No full textThe prevention of seismic risk at urban scale can be pursued through the estimate of the probability to reach or exceed a certain
damage grade given the seismic input. In this framework, seismic fragility curves are nowadays of large interest as they express
this probability in a synthetic way, also extended to large-scale applications. Real damage data are crucial in making more reliable
predictions of damage occurrence, although they can be influenced by a proper definition of the structural types and the
completeness of observations. The paper shows the empirical fragility curves obtained for a sample of 2263 masonry buildings
located within 19 historical centers struck by the 2016 Central Italy earthquake. The damage grade was evaluated according to the
European Macroseismic Scale (EMS-98), also considering undamaged buildings, at the end of the sequence that spanned between
August and October. The buildings largely underwent several repairs and strengthening actions with reinforced concrete elements
starting from the 1980s. The systematization of the structural features led to a taxonomy for strengthened and original buildings,
which, based on the observed damage patterns, was matched to the EMS-98 vulnerability classification. The sample ranges from
class A (worst behavior) to D (best behavior). Class A was typically assigned to original buildings (without interventions) or illadvisedly tampered ones, i.e., those in which interventions had an unfavorable contribution to their seismic behavior. Class D
described buildings with properly designed strengthening interventions, classes B and C intermediate situations. Fragility curves
were obtained per each vulnerability class, as a function of the highest peak ground acceleration (PGA) observed in the sequence
from ShakeMaps. The results were then compared to other empirical fragility model
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