97 research outputs found
Innovations to Improve Lung Isolation Training for Thoracic Anesthesia: A Narrative Review.
A double-lumen tube or bronchial blocker positioning using flexible bronchoscopy for lung isolation and one-lung ventilation requires specific technical competencies. Training to acquire and retain such skills remains a challenge in thoracic anesthesia. Recent technological and innovative developments in the field of simulation have opened up exciting new horizons and possibilities. In this narrative review, we examine the latest development of existing training modalities while investigating, in particular, the use of emergent techniques such as virtual reality bronchoscopy simulation, virtual airway endoscopy, or the preoperative 3D printing of airways. The goal of this article is, therefore, to summarize the role of existing and future applications of training models/simulators and virtual reality simulators for training flexible bronchoscopy and lung isolation for thoracic anesthesia
Shear induced instabilities in layered liquids
Motivated by the experimentally observed shear-induced destabilization and
reorientation of smectic A like systems, we consider an extended formulation of
smectic A hydrodynamics. We include both, the smectic layering (via the layer
displacement u and the layer normal p) and the director n of the underlying
nematic order in our macroscopic hydrodynamic description and allow both
directions to differ in non equilibrium situations. In an homeotropically
aligned sample the nematic director does couple to an applied simple shear,
whereas the smectic layering stays unchanged. This difference leads to a finite
(but usually small) angle between n and p, which we find to be equivalent to an
effective dilatation of the layers. This effective dilatation leads, above a
certain threshold, to an undulation instability of the layers. We generalize
our earlier approach [Rheol. Acta, vol.39(3), 15] and include the cross
couplings with the velocity field and the order parameters for orientational
and positional order and show how the order parameters interact with the
undulation instability. We explore the influence of various material parameters
on the instability. Comparing our results to recent experiments and molecular
dynamic simulations, we find a good qualitative agreement.Comment: 15 pages, 12 figures, accepted for publication in PR
Rich polymorphism of a rod-like liquid crystal (8CB) confined in two types of unidirectional nanopores
We present a neutron and X-rays scattering study of the phase transitions of
4-n-octyl-4'-cyanobiphenyl (8CB) confined in unidirectional nanopores of porous
alumina and porous silicon (PSi) membranes with an average diameter of 30 nm.
Spatial confinement reveals a rich polymorphism, with at least four different
low temperature phases in addition to the smectic A phase. The structural study
as a function of thermal treatments and conditions of spatial confinement
allows us to get insights into the formation of these phases and their relative
stability. It gives the first description of the complete phase behavior of 8CB
confined in PSi and provides a direct comparison with results obtained in bulk
conditions and in similar geometric conditions of confinement but with reduced
quenched disorder effects using alumina anopore membranesComment: Accepted in EPJ E - Soft Matte
Temperature-dependent structure and dynamics of highly-branched poly(N-isopropylacrylamide) in aqueous solution
Small-angle neutron scattering (SANS) and neutron spin-echo (NSE) have been used to investigate the temperature-dependent solution behaviour of highly-branched poly(N-isopropylacrylamide) (HB-PNIPAM). SANS experiments have shown that water is a good solvent for both HB-PNIPAM and a linear PNIPAM control at low temperatures where the small angle scattering is described by a single correlation length model. Increasing the temperature leads to a gradual collapse of HB-PNIPAM until above the lower critical solution temperature (LCST), at which point aggregation occurs, forming disperse spherical particles of up to 60 nm in diameter, independent of the degree of branching. However, SANS from linear PNIPAM above the LCST is described by a model that combines particulate structure and a contribution from solvated chains. NSE was used to study the internal and translational solution dynamics of HB-PNIPAM chains below the LCST. Internal HB-PNIPAM dynamics is described well by the Rouse model for non-entangled chains
Oscillatory Shear Flow-Induced Alignment of Lamellar Melts of Hydrogen-Bonded Comb Copolymer Supramolecules
In this work we present the orientational behavior of comb copolymer-like supramolecules P4VP(PDP)1.0, obtained by hydrogen bonding between poly(4-vinylpyridine) and pentadecylphenol, during large-amplitude oscillatory shear flow experiments over a broad range of frequencies (0.001-10 Hz). The alignment diagram, presenting the macroscopic alignment in T/TODT vs ω/ωc, contains three regions of parallel alignment separated by a region of perpendicular alignment. For our material, the order-disorder temperature TODT = 67 °C and ωc, the frequency above which the distortion of the chain conformation dominates the materials’ viscoelasticity, is around 0.1 Hz at 61 °C. For the first time flipping from a pure transverse alignment via biaxial transverse/perpendicular alignment to a perpendicular alignment as a function of the strain amplitude was found.
Sarcopenic obesity research perspectives outlined by the sarcopenic obesity global leadership initiative (SOGLI) – Proceedings from the SOGLI consortium meeting in rome November 2022
The European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO) launched the Sarcopenic Obesity Global Leadership Initiative (SOGLI) to reach expert consensus on a definition and diagnostic criteria for Sarcopenic Obesity (SO). The present paper describes the proceeding of the Sarcopenic Obesity Global Leadership Initiative (SOGLI) meeting that was held on November 25th and 26th, 2022 in Rome, Italy. This consortium involved the participation of 50 researchers from different geographic regions and countries. The document outlines an agenda advocated by the SOGLI expert panel regarding the pathophysiology, screening, diagnosis, staging and treatment of SO that needs to be prioritized for future research in the field
Recent experimental probes of shear banding
Recent experimental techniques used to investigate shear banding are
reviewed. After recalling the rheological signature of shear-banded flows, we
summarize the various tools for measuring locally the microstructure and the
velocity field under shear. Local velocity measurements using dynamic light
scattering and ultrasound are emphasized. A few results are extracted from
current works to illustrate open questions and directions for future research.Comment: Review paper, 23 pages, 11 figures, 204 reference
Side-chain liquid-crystalline polyacrylates: Experimental evidence of a coexistence of a double main-chain confinement inside the smectic layer
Detailed profiles providing the main-chain/mesogen organisation
within the smectic layers have been deduced from neutron diffraction
measurements, by combination of the coherent scattering length
profiles of the fully hydrogenated and the partially deuterated
side-chain liquid-crystal polymers. Two different sites of the
molecule (either on the main chain or on the mesogen extremity)
have been labelled to prove that main chains can occupy the central
zone of the mesogenic layers whereas most of them remains confined
between the layers of mesogens. This surprising result can be
explained considering symmetry arguments
Side-chain liquid-crystalline polyacrylates: Experimental evidence of a coexistence of a double main-chain confinement inside the smectic layer
The equation providing the profile of the main-chain distribution
\mathrm{Delta}\rho_\ab{main\,chain}(z) on p. 731 is incorrect and should
be replaced by \mathrm{Delta}\rho_\ab{main\,chain}(z) = \rho_\ab{D}(z) -
\rho_\ab{H}(z) = 2(\rho_\ab{H/D}(z) - \rho_\ab{H}(z)).
The corresponding main-chain profile displayed in fig. 2 (continuous
line) is thus globally multiplied by a factor 1.4. This correction
has no incidence on the interpretation of the profile or on the
conclusions drawn in the letter
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