Dimensional reduction, quantum Hall effect and layer parity in graphite films

The quantum Hall effect (QHE) originates from discrete Landau levels forming in a two-dimensional (2D) electron system in a magnetic field. In three dimensions (3D), the QHE is forbidden because the third dimension spreads Landau levels into multiple overlapping bands, destroying the quantisation. Here we report the QHE in graphite crystals that are up to hundreds of atomic layers thick - thickness at which graphite was believed to behave as a 3D bulk semimetal. We attribute the observation to a dimensional reduction of electron dynamics in high magnetic fields, such that the electron spectrum remains continuous only in the direction of the magnetic field, and only the last two quasi-one-dimensional (1D) Landau bands cross the Fermi level. In sufficiently thin graphite films, the formation of standing waves breaks these 1D bands into a discrete spectrum, giving rise to a multitude of quantum Hall plateaux. Despite a large number of layers, we observe a profound difference between films with even and odd numbers of graphene layers. For odd numbers, the absence of inversion symmetry causes valley polarisation of the standing-wave states within 1D Landau bands. This reduces QHE gaps, as compared to films of similar thicknesses but with even layer numbers because the latter retain the inversion symmetry characteristic of bilayer graphene. High-quality graphite films present a novel QHE system with a parity-controlled valley polarisation and intricate interplay between orbital, spin and valley states, and clear signatures of electron-electron interactions including the fractional QHE below 0.5 K

Endosurgical treatment of newborns and young children with posterior urethral valves

Objective: Posterior urethral valves are a rare but the most common cause of lower urinary tract obstruction in male newborns and infants. Patients are at high risk of recurrent urinary tract infections, acute kidney injury and chronic kidney disease. The aim of this study was to present our experience of transurethral incision of posterior urethral valves in newborns as a gold standard of treatment. Materials and methods: We conducted a case-series of patients with posterior urethral valves who underwent transurethral incision during 2017–2021. We analyzed clinical characteristics of patients, recurrence, and complications during a follow-up of 3-12 months. Results: Of 26 patients who underwent transurethral incision of posterior urethra valves 14 had concomitant vesicoureteral reflux of II-V degrees and 12 – obstructive megaureter. Eight children received endoscopic injections (7 ureters) and ureteral stenting (5 ureters). Six infants (9 ureters) had Cohen's operation of which 4 patients had ureteric reimplantation using laparoscopic pneumovesicum and 2 patients underwent open procedure. In 4 cases we performed laparoscopic nephroureterectomy. In 12 children a spontaneous regression of VUR and megaureter within 3 months after TUI were observed. Four children developed chronic kidney disease of 1-2 stages. Conclusions: Early diagnosis and surgery treatment of posterior urethra valves in newborns and infants provide excellent outcomes in most patients. Cystourethroscopy with the transurethral incision is highly recommended to be performed in the neonatal period as the spontaneous recovery of concomitant vesicoureteral reflux and megaureter are quite often

Micromagnetic Modelling of Hysteresis in Permalloy Thin Films with Non-Magnetic Defects

International audienceIn this paper, we present the results of numerical micromagnetic modelling of the domain wall pinning on non-magnetic defects in a ferromagnetic thin sheet of permalloy. We compared the influence of different distribution of non-magnetic inclusions on the magnetization reversal in case of uniaxial anisotropy. It is shown that the non-magnetic defects help to resolve vortex singularities and play a role of pinning states. It is demonstrated that the defects located on the sides of the sheet favor the transition into the single-domain state. By varying the in-plane anisotropy constant, we observed that the defects located in the center lead to higher coercivity, when the domain wall width is comparable to the size of the sample, but narrowing of domain wall width leads to a change of energetically favorable distribution of defects and the highest is when defects are located on the sides. It is shown that the defects located in the corner of the sheet serve as nucleation points for the magnetization reversal process and have a lower threshold for unpinning of the domain walls

Micromagnetic Modelling of Hysteresis in Permalloy Thin Films with Non-Magnetic Defects

International audienceIn this paper, we present the results of numerical micromagnetic modelling of the domain wall pinning on non-magnetic defects in a ferromagnetic thin sheet of permalloy. We compared the influence of different distribution of non-magnetic inclusions on the magnetization reversal in case of uniaxial anisotropy. It is shown that the non-magnetic defects help to resolve vortex singularities and play a role of pinning states. It is demonstrated that the defects located on the sides of the sheet favor the transition into the single-domain state. By varying the in-plane anisotropy constant, we observed that the defects located in the center lead to higher coercivity, when the domain wall width is comparable to the size of the sample, but narrowing of domain wall width leads to a change of energetically favorable distribution of defects and the highest is when defects are located on the sides. It is shown that the defects located in the corner of the sheet serve as nucleation points for the magnetization reversal process and have a lower threshold for unpinning of the domain walls

Micromagnetic modelling of magnetostriction under uniaxial stress

In the current work we present the results of 3D micromagnetic modelling of magnetostrictive strain and magnetic hysteresis under uniaxial stress in ferrite. The simulations are performed on artificial microstructures with different grain orientations that allow to take into account the anisotropy of magnetic and mechanical properties of iron-based alloys. The obtained results are in reasonable agreement with experimental observations. The proposed method opens a path to predictive modelling of the magnetic properties of different textured steels in the context of in-line non-destructive testing

Cerebrospinal Fluid Presepsin As a Marker of Nosocomial Infections of the Central Nervous System: A Prospective Observational Study

BackgroundNosocomial CNS infection (NI-CNS) is a common and serious complication in neurocritical care patients. Timely, accurate diagnosis of NI-CNS is crucial, yet current infection markers lack specificity and/or sensitivity. Presepsin (PSP) is a novel biomarker of macrophage activation. Its utility in NI-CNS has not been explored. We first determined the normal range of cerebrospinal fluid (CSF) PSP in a control group without brain injury before collecting data on CSF PSP levels in neurocritical care patients. Samples were analyzed in four groups defined by systemic and neurological infection status.ResultsCSF PSP levels in 15 control patients without neurological injury were 50–100 pg/ml. Ninety-seven CSF samples were collected from 21 neurocritical care patients. In patients without NI-CNS or systemic infection, CSF PSP was 340.4 ± 201.1 pg/ml. Isolated NI-CNS was associated with CSF PSP levels of 640.8 ± 235.5 pg/ml, while levels in systemic infection without NI-CNS were 580.1 ± 329.7 pg/ml. Patients with both NI-CNS and systemic infection had CSF PSP levels of 1,047.7 ± 166.2 pg/ml. In neurocritical care patients without systemic infection, a cut-off value of 321 pg/ml gives sensitivity and specificity for NI-CNS of 100 and 58.3%, respectively.ConclusionCSF PSP may prove useful in diagnosing NI-CNS, but its current utility is as an additional marker only

How the EU project "Online Microstructure Analytics" advances inline sensing of microstructure during steel manufacturing

Weight savings in mobility and transport are mandatory in order to reduce CO2 emissions and energy consumption. The steel industry offers weight saving solutions by a growing portfolio of Advanced High Strength Steel (AHSS) products. AHSS owe their strength to their largely refined and complex microstructures, containing multiple metallurgical phases. Optimal control of the thermo-mechanical processing of AHSS requires inline sensors for real-time monitoring of evolution and consistency of microstructure and material properties. To coordinate and accelerate European development activities in this domain, the project "Online Microstructure Analytics (OMA)" was established in 2019, constituting of a consortium of 14 specialised research organisations. The EU-funded OMA project

How the EU project "Online Microstructure Analytics" advances inline sensing of microstructure during steel manufacturing

Weight savings in mobility and transport are mandatory in order to reduce CO2 emissions and energy consumption. The steel industry offers weight saving solutions by a growing portfolio of Advanced High Strength Steel (AHSS) products. AHSS owe their strength to their largely refined and complex microstructures, containing multiple metallurgical phases. Optimal control of the thermo-mechanical processing of AHSS requires inline sensors for real-time monitoring of evolution and consistency of microstructure and material properties. To coordinate and accelerate European development activities in this domain, the project "Online Microstructure Analytics (OMA)" was established in 2019, constituting of a consortium of 14 specialised research organisations. The EU-funded OMA project

How the EU project "Online Microstructure Analytics" advances inline sensing of microstructure during steel manufacturing

Weight savings in mobility and transport are mandatory in order to reduce CO2 emissions and energy consumption. The steel industry offers weight saving solutions by a growing portfolio of Advanced High Strength Steel (AHSS) products. AHSS owe their strength to their largely refined and complex microstructures, containing multiple metallurgical phases. Optimal control of the thermo-mechanical processing of AHSS requires inline sensors for real-time monitoring of evolution and consistency of microstructure and material properties. To coordinate and accelerate European development activities in this domain, the project "Online Microstructure Analytics (OMA)" was established in 2019, constituting of a consortium of 14 specialised research organisations. The EU-funded OMA project