1,720,985 research outputs found
CVD-based graphene twistronics
No full textTwisted bilayer graphene (TBG) is certainly the major driving force of the
novel paradigm of twistronics, which aspires at understanding and engineering
the emergent electronic properties of twisted two-dimensional (2D) materials.
The main tool used so far to fabricate TBG is the dry assembly of mechanically
exfoliated flakes, combined with the tear-and-stack technique. However, the
use of exfoliated graphene presents limits in terms of future perspective, scalability
and realistic applications.
In this thesis work, we demonstrate that graphene bilayer twistronics can be
effectively realized by adopting graphene single crystals synthesized with
a scalable approach, i.e., chemical vapor deposition (CVD). Either by direct
growth or by tailored assembly we fabricate TBG, both in the regimes of
large and small twist angle, and we study the electronic properties of these
twisted systems via (magneto)transport, spectroscopic and microscopic measurements.
First, we demonstrate that large-area 30◦-rotated bilayer graphene (30-TBG)
can be deterministically obtained at the growth stage, ensuring electronic decoupling
and parallel transport between pristine graphene sheets with a gatecontrolled
carrier distribution. This results in simultaneous ultrahigh mobility and conductivity, unattainable in a single layer of graphene. Based on the parallel
transport mechanism, we then introduce a method for in situ measurements
of the chemical potential of the two layers. The extent of information
obtained has the potential to greatly simplify the measurement of thermodynamic
quantities in graphene-based systems of high current interest.
In the second part of the thesis we present a tailored approach to realize
high-quality TBG in the small-angle regime (SA-TBG) starting from separated
CVD-grown graphene single crystals. Via low-temperature magnetotransport
measurements on a dual-gated device we populate the moiré bands of a
2.4◦-TBG beyond the van Hove singularities, showing tunability between different
regimes of interlayer coupling. Besides multiple gate-tunable Landau
fans, we observe moiré-induced features, which unambiguously support the
achievement of interface cleanness and device-scale twist-angle uniformity.
The effectiveness of the assembly approach in obtaining twist angles close to
the magic angle (MA) and below it is also demonstrated via scanning probe
techniques and (magneto)transport data.
The realization of twisted bilayer systems with scalable CVD graphene displaying
sharp interfaces and peculiar magnetotransport features is a first step
towards the realization of large-scale twisted systems, which will not only
accellerate fundamental studies but also expand the perspective applicative
potential of these enticing systems. The demonstration of large-scale highquality
hBN (or alternative suitable dielectrics) and of viable solutions to obtain
twist angle control over large areas are two central challenges that will
need to be addressed and overcome in order to fully realize scalable CVD
graphene-based twistronics
Tarsal tunnel syndrome: still more opinions than evidence. Status of the art.
No full textTarsal tunnel syndrome is an entrapment neuropathy of the posterior tibial nerve or its terminal branches within its fibro-osseous tunnel beneath the flexor retinaculum on the medial side of the ankle. The condition is frequently underdiagnosed leading to controversies regarding its epidemiology and to an intense debate in the literature. With the advent of nerve imaging techniques, the diagnostic confirmation and the etiological identification have become more accurate. However, management of this entrapment neuropathy remains challenging because of many intervention strategies but limited robust evidence. Uncertainties still exist about the best conservative treatment, timing of surgical intervention, and best surgical approach. In the attempt to clarify these aspects and to provide the reader some understanding of the status of the art, we have reviewed the published literature on this controversial condition
"Why Do I Feel This Pain?" B-Mode and Power Doppler Ultrasound Found the Answer: A Neurovascular Conflict
No full textNeurovascular conflict (NC) represents a rare condition in which a nerve can be transiently compressed by vascular pulsations. This circumstance might cause pain and motor deficit. This particular condition is usually associated with anatomical variation of the involved vessels and/or nerves. Some reports describe nerve palsies due to vessel abnormalities caused by trauma (i.e., aneurysm
or pseudoaneurysm), but the cases due to anatomical variations without a history of trauma are rarely described. In cases of NC, clinical evaluation is extremely important because it allows clinicians to identify neuropathy signs, and electrophysiology represents the gold standard for the assessment of nerve function, allowing doctors to confirm diagnostic suspicions. Unfortunately, NC may be susceptible to misunderstanding, and sometimes diagnosis is not possible. Because of the ontogenetic features of NC, morphological evaluation could be considered to detect the abnormalities underlying the conflict, and it may be very helpful for the diagnosis. Among the techniques, ultrasound (US), with its ability to show patient anatomy, represents a very useful tool from diagnosis to rehabilitation treatment. This approach can assess nerve and vessels and, hence, may be a potential candidate to
support the diagnosis of NC
Regarding "Current practice of thoracic outlet decompression surgery in the United States"
No full textThoracic outlet syndrome (TOS) is defined as a variety of conditions attributed to involvement of the vascular, muscular, and peripheral nervous system at the cervicobrachial anatomic region. For this reason, medical professionals from several disciplines are involved in its management, from diagnosis to selection of appropriate treatment and, finally, rehabilitation. In a recent review, our group showed that despite its low prevalence and incidence, TOS is the second most discussed nerve entrapment in the scientific literature, trailing only carpal tunnel syndrome (CTS), which is far more common in clinical settings. The high frequency of TOS publications contrasts with its low epidemiologic frequency
Considerations About "Carpal Tunnel Syndrome Grading Using High-Resolution Ultrasonography"
No full textN/
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Improved interoceptive awareness in chronic low back pain: a comparison of Back school versus Feldenkrais method
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