175 research outputs found
Fabrication and electrical characterization of three-dimensional graphitic microchannels in single crystal diamond
We report on the systematic characterization of conductive micro-channels
fabricated in single-crystal diamond with direct ion microbeam writing. Focused
high-energy (~MeV) helium ions are employed to selectively convert diamond with
micrometric spatial accuracy to a stable graphitic phase upon thermal
annealing, due to the induced structural damage occurring at the end-of-range.
A variable-thickness mask allows the accurate modulation of the depth at which
the microchannels are formed, from several {\mu}m deep up to the very surface
of the sample. By means of cross-sectional transmission electron microscopy
(TEM) we demonstrate that the technique allows the direct writing of amorphous
(and graphitic, upon suitable thermal annealing) microstructures extending
within the insulating diamond matrix in the three spatial directions, and in
particular that buried channels embedded in a highly insulating matrix emerge
and electrically connect to the sample surface at specific locations. Moreover,
by means of electrical characterization both at room temperature and variable
temperature, we investigate the conductivity and the charge-transport
mechanisms of microchannels obtained by implantation at different ion fluences
and after subsequent thermal processes, demonstrating that upon
high-temperature annealing, the channels implanted above a critical damage
density convert to a stable graphitic phase. These structures have significant
impact for different applications, such as compact ionizing radiation
detectors, dosimeters, bio-sensors and more generally diamond-based devices
with buried three-dimensional all-carbon electrodes
Evidence for a narrow dip structure at 1.9 GeV/c in diffractive photoproduction
A narrow dip structure has been observed at 1.9 GeV/c in a study of
diffractive photoproduction of the final state performed by the
Fermilab experiment E687.Comment: The data of Figure 6 can be obtained by downloading the raw data file
e687_6pi.txt. v5 (2nov2018): added Fig. 7, the 6 pion energy distribution as
requested by a reade
Design and analysis of cross vaults along history
The history of cross vaults began almost 2,000 years ago with a widespread use during the Middle Ages and Renaissance, becoming nowadays one of the most diffused and fascinating structural typologies of the European building cultural heritage. However, conversely to the undeniable excellence achieved by the ancient masons, the structural behavior of these elements is still at the center of the scientific debate. In this regard, with the aim of reviewing the knowledge on this subject as a concise and valuable support for researchers involved in conservation of historical buildings, with a focus on design rules and structural analysis, the present study firstly introduces the cross vaults from a historical perspective, by describing the evolution of the main geometrical shapes together with basic practical rules used to size them. Then, the article deals with the subsequent advancements in structural analysis methods of vaults, until the development of modern limit analysis.This work was partially carried out under the program "Dipartimento di Protezione Civile - Consorzio RELUIS", signed on 2013-12-27.info:eu-repo/semantics/publishedVersio
Micro-strip sensors based on CVD Diamond
In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation
Performance of irradiated CVD diamond micro-strip sensors
CVD diamond detectors are of interest for charged particle detection and tracking due to their high radiation tolerance. In this article we present, for the first time, beam test results from recently manufactured CVD diamond strip detectors and their behavior under low doses of electrons from a -source and the performance before and after intense () proton- and pion-irradiations. We find that low dose irradiations increase the signal-to-noise ratio (pumping of the signal) and slightly deteriorate the spatial resolution. Intense irradiations with protons () lowers the signal-to-noise ratio slightly. Intense irradiation with pions () lowers the signal-to-noise ratio more. The spatial resolution of the diamond sensors improves after irradiations
Epidemiology of intra-abdominal infection and sepsis in critically ill patients: âAbSeSâ, a multinational observational cohort study and ESICM Trials Group Project
Purpose: To describe the epidemiology of intra-abdominal infection in an international cohort of ICU patients according to a new system that classifies cases according to setting of infection acquisition (community-acquired, early onset hospital-acquired, and late-onset hospital-acquired), anatomical disruption (absent or present with localized or diffuse peritonitis), and severity of disease expression (infection, sepsis, and septic shock). Methods: We performed a multicenter (n = 309), observational, epidemiological study including adult ICU patients diagnosed with intra-abdominal infection. Risk factors for mortality were assessed by logistic regression analysis. Results: The cohort included 2621 patients. Setting of infection acquisition was community-acquired in 31.6%, early onset hospital-acquired in 25%, and late-onset hospital-acquired in 43.4% of patients. Overall prevalence of antimicrobial resistance was 26.3% and difficult-to-treat resistant Gram-negative bacteria 4.3%, with great variation according to geographic region. No difference in prevalence of antimicrobial resistance was observed according to setting of infection acquisition. Overall mortality was 29.1%. Independent risk factors for mortality included late-onset hospital-acquired infection, diffuse peritonitis, sepsis, septic shock, older age, malnutrition, liver failure, congestive heart failure, antimicrobial resistance (either methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producing Gram-negative bacteria, or carbapenem-resistant Gram-negative bacteria) and source control failure evidenced by either the need for surgical revision or persistent inflammation. Conclusion: This multinational, heterogeneous cohort of ICU patients with intra-abdominal infection revealed that setting of infection acquisition, anatomical disruption, and severity of disease expression are disease-specific phenotypic characteristics associated with outcome, irrespective of the type of infection. Antimicrobial resistance is equally common in community-acquired as in hospital-acquired infection
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