Intercalation of graphene on SiC(0001) via ion-implantation

Electronic devices based on graphene technology are catching on rapidly and the ability to engineer graphene properties at the nanoscale is becoming, more than ever, indispensable. Here, we present a new procedure of graphene functionalization on SiC(0001) that paves the way towards the fabrication of complex graphene electronic chips. The procedure resides on the well-known ion-implantation technique. The efficiency of the working principle is demonstrated by the intercalation of the epitaxial graphene layer on SiC(0001) with Bi atoms, which was not possible following standard procedures. Our results put forward the ion-beam lithography to nanostructure and functionalize desired graphene chips

Measurement of the Charge Collection Efficiency after Heavy Non-Uniform Irradiation in BaBar Silicon Detectors

We have investigated the depletion voltage changes, the leakage current increase and the charge collection efficiency of a silicon microstrip detector identical to those used in the inner layers of the BaBar Silicon Vertex Tracker (SVT) after heavy non-uniform irradiation. A full SVT module with the front-end electronics connected has been irradiated with a 0.9 GeV electron beam up to a peak fluence of 3.5 x 10^14 e^-/cm^2, well beyond the level causing substrate type inversion. We irradiated one of the two sensors composing the module with a non-uniform profile with sigma=1.4 mm that simulates the conditions encountered in the BaBar experiment by the modules intersecting the horizontal machine plane. The position dependence of the charge collection properties and the depletion voltage have been investigated in detail using a 1060 nm LED and an innovative measuring technique based only on the digital output of the chip.Comment: 7 pages, 13 figures. Presented at the 2004 IEEE Nuclear Science Symposium, October 18-21, Rome, Italy. Accepted for publication by IEEE Transactions on Nuclear Scienc

Deterministic direct growth of WS2 on CVD graphene arrays

The combination of the exciting properties of graphene with those of monolayer tungsten disulfide (WS2) makes this heterostack of great interest for electronic, optoelectronic and spintronic applications. The scalable synthesis of graphene/WS2 heterostructures on technologically attractive substrates like SiO2 would greatly facilitate the implementation of novel two-dimensional (2D) devices. In this work, we report the direct growth of monolayer WS2 via chemical vapor deposition (CVD) on single-crystal graphene arrays on SiO2. Remarkably, spectroscopic and microscopic characterization reveals that WS2 grows only on top of the graphene crystals so that the vertical heterostack is selectively obtained in a bottom-up fashion. Spectroscopic characterization indicates that, after WS2 synthesis, graphene undergoes compressive strain and hole doping. Tailored experiments show that such hole doping is caused by the modification of the SiO2 stoichiometry at the graphene/SiO2 interface during the WS2 growth. Electrical transport measurements reveal that the heterostructure behaves like an electron-blocking layer at large positive gate voltage, which makes it a suitable candidate for the development of unipolar optoelectronic components

Adatoms and clusters of 3d transition metals on graphene: Electronic and magnetic configurations

We investigate the electronic and magnetic properties of single Fe, Co, and Ni atoms and clusters on monolayer graphene (MLG) on SiC(0001) by means of scanning tunneling microscopy (STM), x-ray absorption spectroscopy, x-ray magnetic circular dichroism (XMCD), and ab initio calculations. STM reveals different adsorption sites for Ni and Co adatoms. XMCD proves Fe and Co adatoms to be paramagnetic and to exhibit an out-of-plane easy axis in agreement with theory. In contrast, we experimentally find a nonmagnetic ground state for Ni monomers while an increasing cluster size leads to sizeable magnetic moments. These observations are well reproduced by our calculations and reveal the importance of hybridization effects and intra-atomic charge transfer for the properties of adatoms and clusters on MLG.Comment: 8 pages (supplementary included), 4 figures, (supplementary included

On the survival of Floquet-Bloch states in the presence of scattering

Floquet theory has spawned many exciting possibilities for electronic structure control with light with enormous potential for future applications. The experimental realization in solids, however, largely remains pending. In particular, the influence of scattering on the formation of Floquet-Bloch states remains poorly understood. Here we combine time- and angle-resolved photoemission spectroscopy with time-dependent density functional theory and a two-level model with relaxation to investigate the survival of Floquet-Bloch states in the presence of scattering. We find that Floquet-Bloch states will be destroyed if scattering -- activated by electronic excitations -- prevents the Bloch electrons from following the driving field coherently. The two-level model also shows that Floquet-Bloch states reappear at high field intensities where energy exchange with the driving field dominates over energy dissipation to the bath. Our results clearly indicate the importance of long scattering times combined with strong driving fields for the successful realization of various Floquet phenomena.Comment: 27 pages, 5 figue

Haemodynamics and oxygenation improvement induced by high frequency percussive ventilation in a patient with hypoxia following cardiac surgery: a case report

<p>Abstract</p> <p>Introduction</p> <p>High frequency percussive ventilation is a ventilatory technique that delivers small bursts of high flow respiratory gas into the lungs at high rates. It is classified as a pneumatically powered, pressure-regulated, time-cycled, high-frequency flow interrupter modality of ventilation. High frequency percussive ventilation improves the arterial partial pressure of oxygen with the same positive end expiratory pressure and fractional inspiratory oxygen level as conventional ventilation using a minor mean airway pressure in an open circuit. It reduces the barotraumatic events in a hypoxic patient who has low lung-compliance. To the best of our knowledge, there have been no papers published about this ventilation modality in patients with severe hypoxaemia after cardiac surgery.</p> <p>Case presentation</p> <p>A 75-year-old Caucasian man with an ejection fraction of 27 percent, developed a lung infection with severe hypoxaemia [partial pressure of oxygen/fractional inspiratory oxygen of 90] ten days after cardiac surgery. Conventional ventilation did not improve the gas exchange. He was treated with high frequency percussive ventilation for 12 hours with a low conventional respiratory rate (five per minute). His cardiac output and systemic and pulmonary pressures were monitored.</p> <p>Compared to conventional ventilation, high frequency percussive ventilation gives an improvement of the partial pressure of oxygen from 90 to 190 mmHg with the same fractional inspiratory oxygen and positive end expiratory pressure level. His right ventricular stroke work index was lowered from 19 to seven g-m/m²/beat; his pulmonary vascular resistance index from 267 to 190 dynes•seconds/cm⁵/m²; left ventricular stroke work index from 28 to 16 gm-m/m²/beat; and his pulmonary arterial wedge pressure was lowered from 32 to 24 mmHg with a lower mean airway pressure compared to conventional ventilation. His cardiac index (2.7 L/min/m²) and ejection fraction (27 percent) did not change.</p> <p>Conclusion</p> <p>Although the high frequency percussive ventilation was started ten days after the conventional ventilation, it still improved the gas exchange. The reduction of right ventricular stroke work index, left ventricular stroke work index, pulmonary vascular resistance index and pulmonary arterial wedge pressure is directly related to the lower respiratory mean airway pressure and the consequent afterload reduction.</p

SuperB: a linear high-luminosity B Factory

This paper is based on the outcome of the activity that has taken place during the recent workshop on "SuperB in Italy" held in Frascati on November 11-12, 2005. The workshop was opened by a theoretical introduction of Marco Ciuchini and was structured in two working groups. One focused on the machine and the other on the detector and experimental issues. The present status on CP is mainly based on the results achieved by BaBar and Belle. Estabilishment of the indirect CP violation in B sector in 2001 and of the direct CP violation in 2004 thanks to the success of PEP-II and KEKB e+e- asymmetric B Factories operating at the center of mass energy corresponding to the mass of the Y(4s). With the two B Factories taking data, the Unitarity Triangle is now beginning to be overconstrained by improving the measurements of the sides and now also of the angles alpha, and gamma. We are also in presence of the very intriguing results about the measurements of sin(2 beta) in the time dependent analysis of decay channels via penguin loops, where b --> s sbar s and b --> s dbar d. Tau physics, in particular LFV search, as well as charm and ISR physics are important parts of the scientific program of a SuperB Factory. The physics case together with possible scenarios for the high luminosity SuperB Factory based on the concepts of the Linear Collider and the related experimental issues are discussed.Comment: 22 pages, 22 figures, INFN Roadmap Repor

The ESR1 (6q25) locus is associated with calcaneal ultrasound parameters and radial volumetric bone mineral density in European men

&lt;p&gt;&lt;b&gt;Purpose:&lt;/b&gt; Genome-wide association studies (GWAS) have identified 6q25, which incorporates the oestrogen receptor alpha gene (ESR1), as a quantitative trait locus for areal bone mineral density (BMD(a)) of the hip and lumbar spine. The aim of this study was to determine the influence of this locus on other bone health outcomes; calcaneal ultrasound (QUS) parameters, radial peripheral quantitative computed tomography (pQCT) parameters and markers of bone turnover in a population sample of European men.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methods:&lt;/b&gt; Eight single nucleotide polymorphisms (SNP) in the 6q25 locus were genotyped in men aged 40-79 years from 7 European countries, participating in the European Male Ageing Study (EMAS). The associations between SNPs and measured bone parameters were tested under an additive genetic model adjusting for centre using linear regression.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Results:&lt;/b&gt; 2468 men, mean (SD) aged 59.9 (11.1) years had QUS measurements performed and bone turnover marker levels measured. A subset of 628 men had DXA and pQCT measurements. Multiple independent SNPs showed significant associations with BMD using all three measurement techniques. Most notably, rs1999805 was associated with a 0.10 SD (95%CI 0.05, 0.16; p = 0.0001) lower estimated BMD at the calcaneus, a 0.14 SD (95%CI 0.05, 0.24; p = 0.004) lower total hip BMD(a), a 0.12 SD (95%CI 0.02, 0.23; p = 0.026) lower lumbar spine BMD(a) and a 0.18 SD (95%CI 0.06, 0.29; p = 0.003) lower trabecular BMD at the distal radius for each copy of the minor allele. There was no association with serum levels of bone turnover markers and a single SNP which was associated with cortical density was also associated with cortical BMC and thickness.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusions:&lt;/b&gt; Our data replicate previous associations found between SNPs in the 6q25 locus and BMD(a) at the hip and extend these data to include associations with calcaneal ultrasound parameters and radial volumetric BMD.&lt;/p&gt

Performance studies of the Belle II Silicon Vertex Detector with data taken at the DESY test beam in April 2016

Belle II is a multipurpose detector currently under construction which will be operated at the next generation B-factory SuberKEKB in Japan. Its main devices for the vertex reconstruction are the Silicon Vertex Detector (SVD) and the Pixel Detector (PXD). In April 2016 a sector of the Belle II SVD and PXD have been tested in a beam of high energetic electrons at the test beam facility at DESY Hamburg (Germany). We report here the results for the hit efficiency estimation and the measurement of the resolution for the Belle II silicon vertex etector. We find that the hit efficiencies are on average above 99.5% and that the measured resolution is within the expectations