Novel Lorentz Force Velocimetry system based on bulk high-temperature superconductors

Die Lorentzkraftanometrie (LKA) ist eine Technik zur Messung der Geschwindigkeit von elektrisch leitfähigen Flüssigkeiten. Sie ist eine nicht-invasive Messtechnik, die besonders vorteilhaft für heiße, opake und aggressive Elektrolyte ist. Die LKA wurde für Salzwasser als Modellelektrolyt erfolgreich mit Dauermagnetanordnungen (DM) ohne magnetischen Rückschluss, aber mit gezielter Flussführung (Halbach-Array) und hochpräzisen Kraftmesssytemen (KMS) auf Basis der interferometrischen Messung der Auslenkung des Magnetsystems und der elektromagnetischen Kompensation der Auslenkung demonstriert. Um die LKA für schwach leitfähige Elektrolyte zu erweitern, ist eine Magnetfelderzeugung von > 1 T erforderlich. Ein Hochtemperatursupraleiter-Bulk (Bulk-HTS) kann ein Magnetfeld von mehreren Tesla erzeugen und somit die LKA-Leistung deutlich verbessern und die bisher genutzten DM ersetzen. Diese Arbeit zielt deshalb darauf ab, Bulk-HTS's in der LKA unter Berücksichtigung der kritischen Verbindungen zwischen der Funktionalität von Bulk-HTS's und dem KMS einzusetzen und ein LKA-System mit Bulk-HTS's zu entwerfen, herzustellen und zu testen. Die Ergebnisse wurden für die Entwicklung eines neuartigen LKA-System auf Basis eines Bulk-HTS als Magnetfeldquelle und einer Torsionswaage als Kraftmesssystem genutzt. Dieses System - Superconducting High-precision Lorentz Force Measurement System (Super-LOFOS) - wurde dann erfolgreich aufgebaut und getestet. Bei Kühlung mit flüssigem Stickstoff bzw. Helium werden auf der Stirnfläche des Super-LOFOS magnetische Flußdichten von B_T = 100 mT bzw. B_T = 1,2 T erzeugt. Damit erweitert die vorliegende Arbeit die Einsetzbarkeit der LKA für gering elektrisch leitende und langsam strömende Fluide auf (σ · u) = 1-10) S s⁻¹, sowie macht hochpräzise Kraftmessungen bis 1 nN unter kryogenen Bedingungen möglich. Darüber hinaus stellt das entwickelte Messsystem Super-LOFOS einen tragbaren Magnetfeldgenerator dar, der für NMR- und MRT-Technologien, Drug Targeting, und magnetische Trennungsverfahren einsetzbar ist.Lorentz Force Velocimentry (LFV) is a technique to measure the velocity of electrically conducting fluids. The advantage of LFV is that this non-invasive measurement method is particularly well suited for use on hot and opaque liquids as well as aggressive electrolytes. LFV for saline water - the model electrolyte - was successfully demonstrated using permanent magnet (PM) configurations without an iron yoke magnetic flux guide, but with targeted magnetic flux guidance (Halbach-array) and a high-precision force measurement system (FMS) based on interferometric measurements of magnet system (MS) deflection and electromagnetic force compensation balance. To extend the LFV for weakly conductive electrolytes, it is required to generate a magnetic field over 1 T. A bulk high-temperature superconsuctors (HTSs) can generate the magnetic field of several teslas and therefore can significantly enhance LFV performance, replacing previously used PM. This thesis aims to integrate the bulk HTS into the LFV considering the critical links between the functionality of bulk HTS and the FMS with the end goal to design, manufacture, and test a novel LFV system using bulk HTS. The obtained results were used to develop a novel LFV system using bulk HTS as magnetic field generator and a torsion balance as FMS. This LFV system - Superconducting High-precision Lorentz Force Measurement System (Super-LOFOS) - was then successfully designed, manufactured, and tested. Using nitrogen and helium cryogenic liquids, the magnetic flux density of B_T = 100 mT and B_T = 1.2 T were generated at the Super-LOFOS front surface, respectively. This thesis also extends the LFV applicability for weakly-conducting and slow-flowing electrolytes (σ · u) = (1-10) S s⁻¹ as well as enabling high-precision force measurements up to 1 nN under cryogenic temperatures. Furthermore, the developed Super-LOFOS provides a portable magnetic field generator, which can be used for NMR and MRI technologies, magnetic separation, and drug targeting applications

Trapped field potential of commercial Y-Ba-Cu-O bulk superconductors designed for applications

Bulk high-temperature superconductors (HTSs) that act as a trap field magnet establish a novel type of magnetic field source, which is significantly different from that of a permanent magnet or solenoid; therefore, they can be potentially used in magnetic-force-based applications. However, the primary issues related to the commercial use of the bulk HTS technology are established on the enhancement of trapped magnetic fields, as well as their reliability and reproducibility at temperatures achievable with off-the-shelf cryocoolers. This study presents experimental investigations on the strong trapped magnetic fields observed in commercial Y-Ba-Cu-O bulk HTSs produced as a double-sample stack, a cylindrical bulk, and a ring-shaped bulk. Consequently, a reliable and reproducible magnetic field of 9.5 T at 50 K was trapped in commercial Y-Ba-Cu-O assembled as a double-sample stack. In this case, shrink-fit encapsulation with either aluminum or stainless steel tube ensured equally effective reinforcement. Higher magnetization, although accompanied with partial flux jumps, yielded a trapped field of 16.85 T at 30 K, which is comparable to the reported record trapped fields. Finally, a maximum trapped field of 9.78 T - the strongest trapped field reported to date - was attained in the 6 mm hollow space of the ring-shaped bulk HTS

Lorentz force velocimetry using a bulk HTS magnet system: proof-of-concept

This paper presents a proof-of-concept of the idea of using bulk high-temperature superconducting (HTS) materials as quasi-permanent magnets that would form, in the future, an integral part of an advanced Lorentz force velocimetry (LFV) system. The experiments, calculations and numerical simulations are performed in accordance with the fundamental theory of LFV, whereby a moving metal rod passes through a static magnetic field, in our case generated by the bulk HTSs. The bulk HTS magnet system (MS) consists of two Y-Ba-Cu-O samples in the form of bulk cylindrical discs, which are encapsulated in an aluminium holder and wrapped with styrofoam. The aluminium holder is designed to locate the bulk HTS magnets on either side of the metal rod. After field cooling magnetisation with an applied field of 1.5 T at 77 K, the bulk HTS MS provides a quasi-permanent magnetic field over 240 s, enabling Lorentz force measurements to be carried out with a constant velocity of the metal rod. Two sets of Lorentz force measurements with copper and aluminium rods with velocities ranging from approximately 54-81 mm s-1 were performed. The obtained results, which are validated using a numerical model developed in COMSOL Multiphysics, demonstrate the linear relationship between the Lorentz force and velocity of the moving conductor. Finally, the potential of generating very high magnetic fields using bulk HTS that would enable LFV in even weakly-conducting and slow-flowing fluids, e.g., glass melts, is discussed

Structure and superconducting characteristics of magnesium diboride, substitution of boron atoms by oxygen and carbon

An x-ray analysis of MgB2-based materials shows that they contain MgB2 and MgO phases. According to a quantitative Auger analysis (taken after removing the oxidized surface layer by Ar ion etching in the microscope chamber) the MgB2 phase contains some amount of oxygen that approximately corresponds to the composition MgB2.2-1.7O0.4-0.6. Rietveld refinement of the MgB2 phase, based on EDX data with varying B/O content, leads to the composition MgB1.68-1.8O0.2-0.32. Ab-initio modelling of boron substitution by oxygen in MgB2 (ΔH f = -150.6 meV/atom) shows that this is energetically favourable up to the composition MgB1.75O0.25 (ΔH f = -191.4 meV/atom). In contrast to carbon substitution, where very small levels of doping can dramatically affect the superconducting characteristics of the material with concomitant changes in the electron density, oxygen substitution results in very little change in the superconducting properties of MgB2. The formation of vacancies at the Mg site of both MgB2 and substituted MgB1.75O0.25 was modelled as well, but has shown that such processes are energetically disadvantageous (ΔHf of Mg0.875B2 and Mg0.75B1.75O0.25 are equal to -45.5 and -93.5 meV/atom, respectively)

Structure and superconducting characteristics of magnesium diboride, substitution of boron atoms by oxygen and carbon

An x-ray analysis of MgB2-based materials shows that they contain MgB2 and MgO phases. According to a quantitative Auger analysis (taken after removing the oxidized surface layer by Ar ion etching in the microscope chamber) the MgB2 phase contains some amount of oxygen that approximately corresponds to the composition MgB2.2-1.7O0.4-0.6. Rietveld refinement of the MgB2 phase, based on EDX data with varying B/O content, leads to the composition MgB1.68-1.8O0.2-0.32. Ab-initio modelling of boron substitution by oxygen in MgB2 ([Delta]Hf =-150.6 meV/atom) shows that this is energetically favourable up to the composition MgB1.75O0.25 ([Delta]Hf =-191.4 meV/atom). In contrast to carbon substitution, where very small levels of doping can dramatically affect the superconducting characteristics of the material with concomitant changes in the electron density, oxygen substitution results in very little change in the superconducting properties of MgB2. The formation of vacancies at the Mg site of both MgB2 and substituted MgB1.75O0.25 was modelled as well, but has shown that such processes are energetically disadvantageous ([Delta]Hf of Mg0.875B2 and Mg0.75B1.75O0.25 are equal to -45.5 and -93.5 meV/atom, respectively)

Structure and superconducting characteristics of magnesium diboride, substitution of boron atoms by oxygen and carbon

An x-ray analysis of MgB2-based materials shows that they contain MgB2 and MgO phases. According to a quantitative Auger analysis (taken after removing the oxidized surface layer by Ar ion etching in the microscope chamber) the MgB2 phase contains some amount of oxygen that approximately corresponds to the composition MgB2.2-1.7O0.4-0.6. Rietveld refinement of the MgB2 phase, based on EDX data with varying B/O content, leads to the composition MgB1.68-1.8O0.2-0.32. Ab-initio modelling of boron substitution by oxygen in MgB2 ([Delta]Hf =-150.6 meV/atom) shows that this is energetically favourable up to the composition MgB1.75O0.25 ([Delta]Hf =-191.4 meV/atom). In contrast to carbon substitution, where very small levels of doping can dramatically affect the superconducting characteristics of the material with concomitant changes in the electron density, oxygen substitution results in very little change in the superconducting properties of MgB2. The formation of vacancies at the Mg site of both MgB2 and substituted MgB1.75O0.25 was modelled as well, but has shown that such processes are energetically disadvantageous ([Delta]Hf of Mg0.875B2 and Mg0.75B1.75O0.25 are equal to -45.5 and -93.5 meV/atom, respectively)

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

The use of massive open online courses in teaching the fundamentals of programming to software engineers

The article describes the possibilities of using massive open online courses (MOOC) in teaching the discipline "Fundamentals of Programming" to students majoring in software engineering. The content of studying the discipline "Fundamentals of Programming" and the number of hours allotted for its study in institutions of higher education in Ukraine is analyzed. When studying the discipline "Fundamentals of Programming" at the Zhytomyr Polytechnic State University, the study of the corresponding course on the platform of massive open online courses Sololearn is submitted for independent work. A description of the possibilities of using this MOOC in teaching the discipline "Fundamentals of Programming" to future specialists in software engineering is presented. In addition, using a pedagogical experiment, the effectiveness of using the Sololearn in teaching the discipline "Fundamentals of Programming" to future software engineering specialists was tested. The results of the pedagogical experiment showed the effectiveness of using the MOOC Sololearn in teaching the "Fundamentals of Programming" to future software engineering specialists

Cardiac myosin activation with omecamtiv mecarbil in systolic heart failure

BACKGROUND The selective cardiac myosin activator omecamtiv mecarbil has been shown to improve cardiac function in patients with heart failure with a reduced ejection fraction. Its effect on cardiovascular outcomes is unknown. METHODS We randomly assigned 8256 patients (inpatients and outpatients) with symptomatic chronic heart failure and an ejection fraction of 35% or less to receive omecamtiv mecarbil (using pharmacokinetic-guided doses of 25 mg, 37.5 mg, or 50 mg twice daily) or placebo, in addition to standard heart-failure therapy. The primary outcome was a composite of a first heart-failure event (hospitalization or urgent visit for heart failure) or death from cardiovascular causes. RESULTS During a median of 21.8 months, a primary-outcome event occurred in 1523 of 4120 patients (37.0%) in the omecamtiv mecarbil group and in 1607 of 4112 patients (39.1%) in the placebo group (hazard ratio, 0.92; 95% confidence interval [CI], 0.86 to 0.99; P = 0.03). A total of 808 patients (19.6%) and 798 patients (19.4%), respectively, died from cardiovascular causes (hazard ratio, 1.01; 95% CI, 0.92 to 1.11). There was no significant difference between groups in the change from baseline on the Kansas City Cardiomyopathy Questionnaire total symptom score. At week 24, the change from baseline for the median N-terminal pro-B-type natriuretic peptide level was 10% lower in the omecamtiv mecarbil group than in the placebo group; the median cardiac troponin I level was 4 ng per liter higher. The frequency of cardiac ischemic and ventricular arrhythmia events was similar in the two groups. CONCLUSIONS Among patients with heart failure and a reduced ejection, those who received omecamtiv mecarbil had a lower incidence of a composite of a heart-failure event or death from cardiovascular causes than those who received placebo. (Funded by Amgen and others; GALACTIC-HF ClinicalTrials.gov number, NCT02929329; EudraCT number, 2016 -002299-28.)