CVD-Enabled Graphene Manufacture and Technology.

Integrated manufacturing is arguably the most challenging task in the development of technology based on graphene and other 2D materials, particularly with regard to the industrial demand for “electronic-grade” large-area films. In order to control the structure and properties of these materials at the monolayer level, their nucleation, growth and interfacing needs to be understood to a level of unprecedented detail compared to existing thin film or bulk materials. Chemical vapor deposition (CVD) has emerged as the most versatile and promising technique to develop graphene and 2D material films into industrial device materials and this Perspective outlines recent progress, trends, and emerging CVD processing pathways. A key focus is the emerging understanding of the underlying growth mechanisms, in particular on the role of the required catalytic growth substrate, which brings together the latest progress in the fields of heterogeneous catalysis and classic crystal/thin-film growth.Funding from the ERC (Grant No. 279342, InSituNANO) and EPSRC (Grant No. EP/K016636/1, GRAPHTED) is acknowledged. R.S.W. acknowledges a research fellowship from St. John’s College, Cambridge.This is the final version of the article. It first appeared from ACS via http://dx.doi.org/10.1021/acs.jpclett.5b0105

Confronto di head-related transfer function personalizzate in ambienti di realtà virtuale

Viene presentato una metodologia per la valutazione comparativa di diversi renderer binaurali basati su personalizzazione del contributo acustico dell'ascoltatore nella simulazione, contenuto nelle head-related transfer function (HRTF). Il metodo si basa sulla classificazione per eliminazione e viene applicato su una lista di attributi percettivi. I renderer messi a confronto per ogni soggetto sono personalizzati su metriche di selezione diverse

Graphene-based low dimensional systems: growth processes and characterization

Questo lavoro di tesi si occupa di sistemi a bassa dimensionalit\ue0 basati su grafene, dalla caratterizzazione delle procedure di crescita fino alla produzione di eterostrutture per la possibile integrazione in dispostivi elettronici di nuova generazione. La prima parte del lavoro \ue8 dedicata alla caratterizzazione, mediante tecniche sperimentali e simulazioni teoriche, del processo di crescita di grafene su metalli di transizione e allo studio dei meccanismi di interazione tra il grafene e il substrato di crescita. Nella seconda parte, due approcci sono proposti per la sintesi di interfacce grafene/ossido di alta qualit\ue0 e per il gating chimico del grafene. La terza parte \ue8 invece focalizzata sulla sintesi di altri sistemi a bassa dimensionalit\ue0 legati al grafene, come il nitruro di boro esagonale e i nanoflakes di grafene. Nella parte finale del lavoro viene descritta nel dettaglio una macchina per la produzione di cluster selezionati in massa attualmente in costruzione presso il Laboratorio di Scienza delle Superfici dell\u2019Universit\ue0 di Trieste e alla cui costruzione e progettazione ho attivamente partecipato durante il periodo di attivit\ue0 dottorale.This thesis work is focused on the characterization of graphene-related low-dimensional systems, from the synthesis to the production of heterostructures for possible integration in new-generation electronic devices. The first part of the work is devoted to the characterization, by means of a combination of experimental techniques and theoretical simulations, of the growth processes of graphene and to the study of the interaction mechanism with transition metal substrates. In the second part two different approaches for the production of high-quality graphene/oxide interfaces and for the chemical gating of graphene are presented. The third part is focused on the synthesis of graphene-related systems like hexagonal boron nitride and graphene nanoflakes. Finally, the last part introduces the mass selected cluster source that is currently under development at the Surface Science Laboratory of the University of Trieste, and in whose design and development I was involved during the PhD activity

Postoperative Dehydration Is Associated with Frailty and Decreased Survival in Older Patients with Hip Fracture

Background: Hyperosmolar dehydration (HD) is a risk factor for severe complications in hip fracture in older patients. However, evidence for recommending screening of dehydration is insufficient and its relation with frailty and mortality is unclear. We tested the hypothesis that postoperative HD is associated with frailty and increased mortality. Methods: We recruited 625 older (>65 years) patients surgically treated for hip fracture and co-managed by an orthogeriatric team over one year in 2017. Pre-and postoperative HD (serum osmolarity > 300 mmol/L) was diagnosed. Frailty and associated mortality risk were assessed by the Multidimensional Prognostic Index (MPI). Results: The prevalence of preoperative HD was 20.4%. Compared with no-HD, MPI was similar in HD patients despite higher (p < 0.05) prevalence of polypharmacy, arterial hypertension, diabetes, chronic kidney disease and heart failure. After surgery the incidence of HD decreased to 16.5%, but increased (p = 0.003) in the MPI high-risk subgroup. Postoperative HD was associated with more complications and was an independent determinant of adjusted hospital length of stay (LOS) and of 60-to 365-days mortality. Conclusions: Older frail patients with hip fracture are prone to developing postoperative HD, which independently predicts prolonged hospital LOS and mortality. Systematically screening older patients for frailty and dehydration is advisable to customize hydration management in high-risk individuals

Distribution of the vasoconstrictor and vasorelaxant effects of norbormide along the vascular tree of the rat

Norbormide is a vasoconstrictor of rat peripheral arteries and a relaxant in rat aorta. To characterise norbormide actions within the rat vascular tree we have investigated its effects on the contractile function of rings from several arteries and veins. A maximal norbormide concentration (50 muM) failed to contract thoracic aorta and carotid artery, whereas in pulmonary artery, abdominal aorta, iliac, caudal, and femoral arteries it induced a contractile effect that was respectively 4.8 +/- 0.6, 18.4 +/- 1.5, 39 +/- 5, 144 +/- 7, and 260 +/- 22% of that induced by 90 MM KCl. In pulmonary, carotid, and iliac arteries, and in thoracic and abdominal aorta, 50 muM norbormide inhibited KCl-induced responses. Norbormide (50 muM) contracted all veins investigated. The effect, expressed as % of KCl-induced contraction, was 121 +/- 25, 154 +/- 14.5, 154 +/- 18.2, 203 +/- 19, and 267 +/- 33 for pulmonary vein, thoracic and abdominal vena cava, iliac and jugular veins, respectively. In jugular vein, as previously shown in rat caudal artery, norbormide contraction was abolished in Ca2+-free medium, was unaffected by the Ca2+ channel blocker nifedipine, and was relaxed by SK&F 96365, a blocker of store-operated Ca2+ channels. In conclusion: i) rat veins represent the main target for contractile norbormide action; ii) in both artery and veins norbormide contractions are generally inversely related, to the calibre of the vessel; iii) norbormide-induced contraction is mediated by the same mechanism/s in arteries and veins; iiii) in norbormide-contracted arteries the drug activates both contractile and relaxing mechanisms. (C) 2004 Elsevier Inc. All rights reserved

Chemical gating of epitaxial graphene through ultrathin oxide layers

We achieved a controllable chemical gating of epitaxial graphene grown on metal substrates by exploiting the electrostatic polarization of ultrathin SiO2 layers synthesized below it. Intercalated oxygen diffusing through the SiO2 layer modifies the metal\u2013oxide work function and hole dopes graphene. The graphene/oxide/metal heterostructure behaves as a gated plane capacitor with the in situ grown SiO2 layer acting as a homogeneous dielectric spacer, whose high capacity allows the Fermi level of graphene to be shifted by a few hundreds of meV when the oxygen coverage at the metal substrate is of the order of 0.5 monolayers. The hole doping can be finely tuned by controlling the amount of interfacial oxygen, as well as by adjusting the thickness of the oxide layer. After complete thermal desorption of oxygen the intrinsic doping of SiO2 supported graphene is evaluated in the absence of contaminants and adventitious adsorbates. The demonstration that the charge state of graphene can be changed by chemically modifying the buried oxide/metal interface hints at the possibility of tuning the level and sign of doping by the use of other intercalants capable of diffusing through the ultrathin porous dielectric and reach the interface with the metal