Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.
BACKGROUND: The HeartMate 3 (HM3) is a Conformiteé Européenne (CE) mark-approved left ventricular assist device (LVAD) with a fully magnetically levitated rotor with features consisting of a wide range of operational speeds, wide flow paths and an artificial pulse. We performed a hemodynamic and echocardiographic evaluation of patients implanted with the HM3 LVAD to assess the speed range for optimal hemodynamic support. METHODS: Sixteen HM3 patients underwent pump speed ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP] and blood pressure [BP]) and 3-dimensional echocardiography (3DE). Data were recorded at up to 13 speed settings. Speed changes were in steps of 100 revolutions per minute (rpm), starting at 4,600 rpm and ramping up to 6,200 rpm. RESULTS: Mean original speed was 5,306 ± 148 rpm, with a majority of patients (10 of 16, 62.5%) having normal CVPs and PCWPs at their original rpm settings. Going from lowest to highest speeds, cardiac output improved at the rate of 0.08 ± 0.08 liter/min per 100 rpm (total change 1.25 ± 1.20 liters/min) and PCWP decreased at the rate of -0.48 ± 0.27 mm Hg per 100 rpm (total change -6.13 ± 3.72 mm Hg). CVP and systolic BP did not change significantly with changes in rpm. Left ventricular end-diastolic dimension (LVEDD) decreased at a rate of -0.15 ± 0.09 cm per 100 rpm. Number of rpm was adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in 13 (81.3%) patients. For the remaining 3 patients, medical management was pursued to optimize hemodynamic support. CONCLUSION: Hemodynamic normalization of pressures was achieved in the majority of patients implanted with the HM3 pump within a narrow speed range.
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- časové faktory MeSH
- design vybavení MeSH
- funkce levé komory srdeční fyziologie MeSH
- hemodynamika fyziologie MeSH
- lidé MeSH
- magnetismus přístrojové vybavení MeSH
- následné studie MeSH
- podpůrné srdeční systémy * MeSH
- prospektivní studie MeSH
- senioři MeSH
- srdeční selhání patofyziologie chirurgie MeSH
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- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
Hypothermia is an effective neuroprotective strategy for acute stroke. However, in clinical practice, the induction of hypothermia is achieved through the systemic reduction of body temperature (using thermal covers or endovascular cooling devices) which results in a complex system associated in many cases to side effects. Therefore, the aim of this study was to test the magnetocaloric effect as a potential new therapeutic strategy for stroke by means of an adiabatic magnetic refrigerator device. As a first approach, we have developed a simple device to evaluate in vitro the thermodynamic behavior of different concentrations of commercial gadolinium powder as a reference magnetocaloric material. The samples, properly thermally insulated, were cyclically magnetized and demagnetized at room temperature by 1 T permanent magnets in order to induce an adiabatic magnetic effect. Under the experimental conditions tested, results showed a maximun non-accumulative temperature variation of 0.2 °C, insufficient to carry out an effective hypothermia. This study allowed us to discuss about the use of new materials and strategies for further in vivo experiments.
- MeSH
- biokompatibilní materiály MeSH
- cévní mozková příhoda terapie MeSH
- gadolinium MeSH
- magnetické pole MeSH
- magnetismus metody přístrojové vybavení MeSH
- techniky in vitro MeSH
- tepelná vodivost MeSH
- terapeutická hypotermie * metody přístrojové vybavení MeSH
- Publikační typ
- práce podpořená grantem MeSH
- MeSH
- financování organizované MeSH
- kovové nanočástice diagnostické užití MeSH
- krysa rodu rattus MeSH
- magnetismus přístrojové vybavení MeSH
- potkani Wistar MeSH
- testování materiálů metody přístrojové vybavení MeSH
- tkáňová distribuce MeSH
- železité sloučeniny aplikace a dávkování farmakokinetika MeSH
- zvířata MeSH
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- krysa rodu rattus MeSH
- zvířata MeSH
- MeSH
- biofyzika metody přístrojové vybavení trendy MeSH
- diagnostické zobrazování metody využití MeSH
- elektromagnetická pole MeSH
- financování organizované MeSH
- játra účinky léků MeSH
- lidé MeSH
- magnetismus metody přístrojové vybavení trendy MeSH
- počítačové zpracování obrazu metody využití MeSH
- počítačové zpracování signálu MeSH
- přetížení železem diagnóza MeSH
- slezina účinky léků MeSH
- spektrofotometrie atomová trendy využití MeSH
- statistika jako téma MeSH
- teoretické modely MeSH
- železo izolace a purifikace metabolismus MeSH
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- lidé MeSH
- MeSH
- kardiochirurgické výkony metody přístrojové vybavení trendy MeSH
- kardiovaskulární nemoci diagnóza terapie MeSH
- katetrizace metody přístrojové vybavení využití MeSH
- katetrizační ablace metody přístrojové vybavení využití MeSH
- lidé MeSH
- magnetismus přístrojové vybavení trendy MeSH
- robotika metody přístrojové vybavení využití MeSH
- zobrazování trojrozměrné metody přístrojové vybavení využití MeSH
- Check Tag
- lidé MeSH
One of the most recent fi elds of the SQUID magnetometric systems applications is the measurement of ferritin content in the human liver. Th is magnetic susceptibility measurement is complicated with the signal selection from the relatively strong disturbing from the surrounding tissue. A method how to solve this problem is based on idea of the volume- and shape-identical model of the magnetized object consisting of a set of identical small elements, each with the same intrinsic magnetic moment represented by circular current loop supplied by defi ned current. Electronic model behaves like the sample in the magnetization fi eld. Th is idea has been proved by SQUID gradiometer measurements on real samples with known susceptibility and on liver samples.
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- biomedicínské inženýrství metody přístrojové vybavení MeSH
- elektromagnetické jevy MeSH
- ferritiny diagnostické užití MeSH
- financování organizované MeSH
- játra chemie metabolismus MeSH
- lékařská elektronika metody přístrojové vybavení MeSH
- lidé MeSH
- magnetismus přístrojové vybavení MeSH
- počítačové zpracování signálu MeSH
- teoretické modely MeSH
- využití lékařské informatiky MeSH
- Check Tag
- lidé MeSH
