Interplay of the Kondo effect and strong spin-orbit coupling in multihole ultraclean carbon nanotubes.

We report on cotunneling spectroscopy magnetoconductance measurements of multihole ultraclean carbon nanotube quantum dots in the SU(4) Kondo regime with strong spin-orbit coupling. Successive shells show a gradual weakening of the Kondo effect with respect to the spin-orbital splittings, leading to an evolution from SU(4) to SU(2) symmetry with a suppressed conductance at half-shell filling. The extracted energy level spectrum, overall consistent with negligible disorder in the nanotube, shows in the half filled case large renormalizations due to Coulombian effects.

Supramolecular spin valves.

Magnetic molecules are potential building blocks for the design of spintronic devices. Moreover, molecular materials enable the combination of bottom-up processing techniques, for example with conventional top-down nanofabrication. The development of solid-state spintronic devices based on the giant magnetoresistance, tunnel magnetoresistance and spin-valve effects has revolutionized magnetic memory applications. Recently, a significant improvement of the spin-relaxation time has been observed in organic semiconductor tunnel junctions, single non-magnetic molecules coupled to magnetic electrodes have shown giant magnetoresistance and hybrid devices exploiting the quantum tunnelling properties of single-molecule magnets have been proposed. Herein, we present an original spin-valve device in which a non-magnetic molecular quantum dot, made of a single-walled carbon nanotube contacted with non-magnetic electrodes, is laterally coupled through supramolecular interactions to TbPc(2) single-molecule magnets (Pc=phthalocyanine). Their localized magnetic moments lead to a magnetic field dependence of the electrical transport through the single-walled carbon nanotube, resulting in magnetoresistance ratios up to 300% at temperatures less than 1 K. We thus demonstrate the functionality of a supramolecular spin valve without magnetic leads. Our results open up prospects of new spintronic devices with quantum properties.

Magneto-Coulomb effect in carbon nanotube quantum dots filled with magnetic nanoparticles.

Electrical transport measurements of carbon nanotubes filled with magnetic iron nanoparticles are reported. Low-temperature (40 mK) magnetoresistance measurements showed conductance hysteresis with sharp jumps at the switching fields of the nanoparticles. Depending on the gate voltage, positive or negative hysteresis was observed. The results are explained in terms of a magneto-Coulomb effect: The spin flip of the iron island at a nonzero magnetic field causes a shift of the chemical potential induced by the change of Zeeman energy; i.e., an effective charge variation is detected by the nanotube quantum dot.

Primary resection of Kommerell's diverticulum in a 37-year-old patient.

A previously non-operated 37-year-old patient presented with esophageal dysphagia for solid food and stridorous breathing. Computed tomography and magnetic resonance showed a 33-mm wide Kommerell's diverticulum. The diverticulum and the obliterated ductus arteriosus arising from it towards the pulmonary artery were resected. The left subclavian artery, which originated from the diverticulum, was reimplanted into the descending aorta. In addition to dissecting any tissue which is making vascular ring-like structures around the trachea and the esophagus, it is important to resect the diverticulum itself and reimplant the left subclavian artery arising from it, in this way leaving the aortic arch free from any additional dislocating forces.

Total body irradiation using helical tomotherapy: Set-up experience and in-vivo dosimetric evaluation.

PURPOSE: Helical Tomotherapy (HT) appears as a valuable technique for total body irradiation (TBI) to create highly homogeneous and conformal dose distributions with more precise repositioning than conventional TBI techniques. The aim of this work is to describe the technique implementation, including treatment preparation, planning and dosimetric monitoring of TBI delivered in our institution from October 2016 to March 2019. MATERIAL AND METHOD: Prior to patient care, irradiation protocol was set up using physical phantoms. Gafchromic films were used to assess dose distribution homogeneity and evaluate imprecise patient positioning impact. Sixteen patients' irradiations with a prescribed dose of 12Gy were delivered in 6 fractions of 2Gy over 3 days. Pre-treatment quality assurance (QA) was performed for the verification of dose distributions at selected positions. In addition, in-vivo dosimetry was carried out using optically stimulated luminescence dosimeters (OSLD). RESULTS: Planning evaluation, as well as results of pre-treatment verifications, are presented. In-vivo dosimetry showed the strong consistency of OSLD measured doses. OSLD mean relative dose differences between measurement and calculation were respectively +0,96% and -2% for armpit and hands locations, suggesting better reliability for armpit OSLD positioning. Repercussion of both longitudinal and transversal positioning inaccuracies on phantoms is depicted up to 2cm shifts. CONCLUSION: The full methodology to set up TBI protocol, as well as dosimetric evaluation and pre-treatment QA, were presented. Our investigations reveal strong correspondence between planned and delivered doses shedding light on the dose reliability of OSLD for HT based TBI in-vivo dosimetry.

Predictors for biventricular repair in pulmonary atresia with intact ventricular septum.

BACKGROUND: Pulmonary atresia with intact ventricular septum (PA-IVS) is a complex congenital heart defect with a large variety of right heart-sided morphologies. METHODS: We undertook a retrospective review of 86 patients with PA-IVS with a special emphasis on the angiographic findings. The aim of the study was to determine predictors for biventricular repair. Initial surgical procedures depended on the right ventricular morphology, the tricuspid valve size and coronary anomalies. RESULTS: Fifty-five patients (64%) underwent decompression of the right ventricle (RV) as an initial procedure; 16 of them required an additional systemic-to-pulmonary artery shunt. Twenty-six patients (30%) had only a systemic-to-pulmonary artery shunt as their initial procedure. Five patients underwent interventional procedures performed by pediatric cardiologists. Biventricular repair was possible in 56 patients (65%). Univentricular palliation was achieved in 16 patients. Fourteen patients had only palliation with a systemic-to-pulmonary artery shunt. Mean tricuspid valve size was significantly bigger in patients with biventricular repair (z-score -3.6 +/- 2.6) than in patients who did not undergo biventricular repair (-5.2 +/- 1.7, P = 0.003). Predictors for biventricular repair were right ventricular decompression with or without systemic-to-pulmonary artery shunt ( P < 0.001), tripartite right ventricle ( P < 0.001) and the absence of coronary fistulae ( P < 0.001). Long-term survival was 80% +/- 13% at 25 years for patients undergoing biventricular repair. CONCLUSIONS: Decompression of the RV as an initial surgical procedure improves the possibility of achieving biventricular repair with good long-term results. However, morphological factors such as right ventricular size and the absence of coronary fistulae are significant predictors for biventricular repair.

Neonates and infants requiring life-long cardiac pacing: How reliable are epicardial leads through childhood?

BACKGROUND: In the literature, data is lacking on mid-term results of epicardial pacemaker implantation in neonates and infants. Our aim was to evaluate the mid-term results of epicardial pacemakers implanted in infants under 1 year of age. METHODS AND RESULTS: We conducted a retrospective review of patients who underwent pacemaker implantation between 2000 and 2017. Pacemaker and lead parameters were reviewed at discharge, 2, 4 and more than 5 years after implantation. A total of 71 patients aged 4 ±â€¯3 months and weighing 4 ±â€¯2 kg were included in the study. Indications for pacemaker implantation were: acquired AV-block (n = 44), congenital AV block (n = 22), sick sinus syndrome (n = 4) and AV block type Mobitz II (n = 1). Median follow-up time was 5 years (range: 1 month-17 years). At 5 years of follow-up, atrial lead energy threshold for pacing decreased significantly (0.72 ±â€¯0.71 µJ to 0.45 ±â€¯0.35 µJ; P < 0.001) but was stable for ventricular leads (0.57 µJ [0.05; 39.47] to 0.64 µJ [0.13; 9.45], P = 0.97). Atrial lead impedance increased significantly (569 ±â€¯137 Ω to 603 ±â€¯134 Ω, P < 0.001), whereas ventricular lead impedance decreased (603 ±â€¯202 Ω to 490 ±â€¯150 Ω, P < 0.001) after 5 years. Repeat operations were required for generator change (n = 55), lead exchange (n = 17) and infection (n = 1). At 2, 5 and 10 years, atrial lead survival was 96%, 91% and 76% and ventricular lead survival was 94%, 82% and 75%, respectively (P = 0.45). CONCLUSION: Stable pacing thresholds after 5 years indicated that epicardial pacemakers are safe for infants under 1 year of age until at least school enrolment age. However, due to stimulation at higher heart rates in infancy, battery depletion is a frequent occurrence.

Charge localization and reentrant superconductivity in a quasi-ballistic InAs nanowire coupled to superconductors.

A semiconductor nanowire with strong spin-orbit coupling in proximity to a superconductor is predicted to display Majorana edge states emerging under a properly oriented magnetic field. The experimental investigation of these exotic states requires assessing the one-dimensional (1D) character of the nanowire and understanding the superconducting proximity effect in the presence of a magnetic field. Here, we explore the quasi-ballistic 1D transport regime of an InAs nanowire with Ta contacts. Fine-tuned by means of local gates, the observed plateaus of approximately quantized conductance hide the presence of a localized electron, giving rise to a lurking Coulomb blockade effect and Kondo physics. When Ta becomes superconducting, this local charge causes an unusual, reentrant magnetic field dependence of the supercurrent, which we ascribe to a 0 - π transition. Our results underline the relevant role of unintentional charge localization in the few-channel regime where helical subbands and Majorana quasi-particles are expected to arise.

Balloon-expandable stents for recoarctation of the aorta in small children. Two centre experience.

BACKGROUND: In young patients with native aortic coarctation (CoA), the management of choice is surgery. However, in re-coarctation (re-CoA) surgery is associated with increased morbidity and even mortality. Some children with native CoA present relative contraindications for surgery. METHODS: From 2006 to 2017, thirty-four patients (male n = 20; 59%) from two centres with re-CoA (31) and native CoA (3) were managed by stent implantation with premounted balloon expandable stents. Inclusion criteria were age < 3 years and >1 month, weight < 16 kg. Median age was 6,5 months (min. 1; max. 34 months), median weight 6,2 kg (min. 3,7; max. 16 kg). Thirteen patients (38%) had Re-CoA and hypoplastic left heart syndrome (HLHS). In three patients (9%) the native CoA was stented due to contraindications for surgical treatment. RESULTS: All procedures were successful. The median peak invasive systolic pressure gradient declined from 31 mm Hg (max. 118; min. 4) to 0 mm Hg (max. 32; min.-7) (p < 0.001). The median minimal diameter of the narrowed segment of aorta increased from 3 mm (max. 6,9; min. 1,0) to 7 mm (max. 11,5; min. 3,5) (p < 0.001). There were no serious complications. The median follow-up time was 12,5 months (max. 88; min. 0 month). During this time ten patients (29%) required re-dilatation and two of them re-stenting. CONCLUSION: Percutaneous stent implantation for Re-CoA and in selected patients for native CoA can be performed successfully in very young patients with a good immediate hemodynamical result. However, repeated stent angioplasties and further on interventional 'opening' of the stent is necessary to augment the aorta to adult size.

Outcome after surgical repair/palliation of congenitally corrected transposition of the great arteries.

BACKGROUND: The surgical concepts for patients with congenitally corrected transposition of the great arteries (CCTGA) address discordant connections and associated lesions. The outcomes after biventricular repair without correction of discordant connections ("classic repair", or with its correction "anatomic repair") and after "univentricular palliation" were investigated. METHODS: All patients with CCTGA who underwent "classic repair" (n = 39), "anatomic repair" (n = 6), or "univentricular palliation" (n = 11) between 1978 and 2006 were analyzed. The most frequently associated lesions were ventricular septal defect (n = 48), tricuspid insufficiency (TI) (n = 20) and functionally single ventricle (n = 11). RESULTS: Thirty-day mortality was 4 % (2/56). Mean follow-up for early survivors was 7.2 +/- 7.1 years. Eight patients died late, two after heart transplantation. Survival was not significantly different between patients who underwent "anatomic" or "classic repair", or "univentricular palliation": 83.3 +/- 15.2 %, 79.7 +/- 6.9 %, 90.9 +/- 8.7 % at 10 years, respectively. In multivariate analysis, the presence of TI emerged as the only risk factor for late death ( P = 0.004). Twenty patients required reoperation, mainly for TI (n = 10) and conduit failure (n = 6). Freedom from reoperation was lower after "anatomic repair", but ventricular function was better and atrioventricular valves were more competent than after "classic repair". CONCLUSIONS: Biventricular "anatomic" or "classic repair" and "univentricular palliation" yield equivalent survival rates in the mid-term. Biventricular "anatomic repair", when feasible, should be promoted because of its better long-term outcome.

How well are patients doing up to 30 years after a mustard operation?

BACKGROUND: Right heart failure and baffle complications may affect the health status of patients with transposition of the great arteries after an atrial switch operation. METHODS: This study aims to identify risk factors for late death, the incidence of reoperations, and the functional status of 88 patients who underwent a Mustard operation with a mean follow-up of 20.9 +/- 10.0 years. RESULTS: There were 7 early and 19 late deaths. Follow-up was complete for 97 % of the hospital survivors. Survival and freedom from reoperation of the hospital survivors at 20 years was 83.7 +/- 4.2 %, and 70.6 +/- 5.4 %, respectively. Seven reoperations were performed for systemic ventricular failure, and 24 for baffle complications, with no operative mortality. Presence of a ventricular septal defect at the time of the Mustard operation was predictive for late death in multivariate analysis ( P = 0.040). At follow-up, 82 % of the patients were able to work full-time, 11 % part-time, and 7 % experienced noticeable limitations of their activities. CONCLUSIONS: Presence of a VSD at the time of the Mustard operation defines a distinct subgroup with an increased risk for late death. Long-term survivors were in a good functional status but had to be reoperated frequently due to baffle complications that seemed to increase in adulthood.

Surgical closure of atrial septal defect in patients older than 30 years: risk factors for late death from arrhythmia or heart failure.

BACKGROUND: Little is known about prognostic markers for late cardiac-related death after surgical atrial septal defect (ASD) closure in adults. METHODS: Long-term follow-up data of 281 patients who underwent surgical secundum ASD closure when they were older than 30 years, were retrospectively examined. RESULTS: Mean age at surgery was 43.8 +/- 10.0 years (30 to 76 years). There were 2 early deaths. Mean follow-up was 14.1 +/- 8.4 years (0.4 to 28.9 years). Death from arrhythmia or heart failure occurred in 9 patients (3.6 %) at a mean time of 8.5 +/- 6.6 years after the operation. Patients > 43 years exhibited significantly higher pulmonary artery pressures. Preoperative systolic pulmonary artery pressure > 36 mmHg, and mean pulmonary artery pressure > 21 mmHg were predictive of late death from arrhythmia or heart failure. However, age at operation was not. CONCLUSIONS: Older age at the time of ASD closure is not a risk factor for late death from arrhythmia or heart failure in adults. However, older patients presented more often with pulmonary hypertension. Since elevated pulmonary artery pressure is predictive of late death from arrhythmia or heart failure, timely ASD closure is warranted.

Gate-tuned high frequency response of carbon nanotube Josephson junctions.

Carbon nanotube Josephson junctions in the open quantum dot limit are fabricated using Pd/Al bilayer electrodes, and exhibit gate-controlled superconducting switching currents. Shapiro voltage steps can be observed under radio frequency current excitations, with a damping of the phase dynamics that strongly depends on the gate voltage. These measurements are described by a standard resistively and capacitively shunted junction model showing that the switching currents from the superconducting to the normal state are close to the critical current of the junction. The effective dynamical capacitance of the nanotube junction is found to be strongly gate dependent, suggesting a diffusive contact of the nanotube.

Aharonov-Bohm conductance modulation in ballistic carbon nanotubes.

We report on magnetoconductance experiments in ballistic multiwalled carbon nanotubes threaded by magnetic fields as large as 55 T. In the high temperature regime (100 K), giant modulations of the conductance, mediated by the Fermi level location, are unveiled. The experimental data are consistently analyzed in terms of the field-dependent density of states of the external shell that modulates the injection properties at the electrode-nanotube interface, and the resulting linear conductance. This is the first unambiguous experimental evidence of Aharonov-Bohm effect in clean multiwalled carbon nanotubes.

Carbon nanotube superconducting quantum interference device.

A superconducting quantum interference device (SQUID) with single-walled carbon nanotube (CNT) Josephson junctions is presented. Quantum confinement in each junction induces a discrete quantum dot (QD) energy level structure, which can be controlled with two lateral electrostatic gates. In addition, a backgate electrode can vary the transparency of the QD barriers, thus permitting change in the hybridization of the QD states with the superconducting contacts. The gates are also used to directly tune the quantum phase interference of the Cooper pairs circulating in the SQUID ring. Optimal modulation of the switching current with magnetic flux is achieved when both QD junctions are in the 'on' or 'off' state. In particular, the SQUID design establishes that these CNT Josephson junctions can be used as gate-controlled pi-junctions; that is, the sign of the current-phase relation across the CNT junctions can be tuned with a gate voltage. The CNT-SQUIDs are sensitive local magnetometers, which are very promising for the study of magnetization reversal of an individual magnetic particle or molecule placed on one of the two CNT Josephson junctions.