Search results for " Impedance"

Poli(ēterēterketona)-alkilimidazolija jonu šķidrumu kompozīto membrānu mehānisko īpašību un elektrovadītspējas pētīšana

2015

Poli(ēterēterketona)-alkilimidazolija jonu šķidrumu kompozīto membrānu mehānisko īpašību un elektrovadītspējas pētīšana. Sprūģis E., zinātniskais vadītājs Dr. chem., doc. Vaivars G. Maģistra darbs, 40 lappuses, 30 attēli, 1 tabula, 38 literatūras avoti. Latviešu valodā. Darbā tika veikta mehānisko īpašību analīze temperatūru intervālā no 20 °C līdz 200 °C sekojošām kompozītmembrānām: sulfonēta poli(ēterēter)ketona (SPĒĒK)-1,3-dimetilimidazolija dimetilfosfāts, SPĒĒK-1,2,3-trimetilimidazolija dimetilfosfāts, SPĒĒK-1-butil-2,3-dimetilimidazolija dimetilfosfāts. Intervālā no 30 °C līdz 150 °C sekojošām kompozītmembrānām tika veikta elektrovadītspējas pētīšana, izmantojot elektroķīmiskās impeda…

Kramers–Kronig transformation, dc behaviour and steady state response of the Warburg impedance for a disk electrode inlaid in an insulating surface

2002

Abstract As the frequency approaches zero, the impedance described by the Warburg function tends to infinity. This means that the resistance of the equivalent circuit representing the electrochemical process has an infinite resistor and then the current cannot flow through it. This asymptotic behaviour also prevents the application of the Kramers–Kronig transformations, a set of integrals which should be fulfilled by any linear system. Using a more general expression of the impedance for a disk electrode inlaid in an insulating surface developed by Fleischmann and Pons (J. Electroanal. Chem. 250 (1988) 277), the Warburg impedance can be deduced and the Kramers–Kronig transformation is possi…

Can PBDEs affect the pathophysiologic complex of epithelium in lung diseases?

2020

Brominated flame-retardant (BFRs) exposure promotes multiple adverse health outcomes involved in oxidative stress, inflammation, and tissues damage. We investigated BFR effects, known as polybrominated diphenyl ethers (PBDEs) (47, 99 and 209) in an air-liquid-interface (ALI) airway tissue derived from A549 cell line, and compared with ALI culture of primary human bronchial epithelial cells (pHBEC). The cells, exposed to PBDEs (47, 99 and 209) (0.01-1 mu M) for 24 h, were studied for IL-8, Muc5AC and Muc5B (mRNAs and proteins) production, as well as NOX-4 (mRNA) expression. Furthermore, we evaluated tight junction (TJ) integrity by Trans-Epithelial Electrical Resistance (TEER) measurements, …

Chest electrical impedance tomography examination, data analysis, terminology, clinical use and recommendations: consensus statement of the translati…

2017

Electrical impedance tomography (EIT) has undergone 30 years of development. Functional chest examinations with this technology are considered clinically relevant, especially for monitoring regional lung ventilation in mechanically ventilated patients and for regional pulmonary function testing in patients with chronic lung diseases. As EIT becomes an established medical technology, it requires consensus examination, nomenclature, data analysis and interpretation schemes. Such consensus is needed to compare, understand and reproduce study findings from and among different research groups, to enable large clinical trials and, ultimately, routine clinical use. Recommendations of how EIT findi…

Principles of electrical impedance tomography and its clinical application

2008

This review outlines the basic principle, in addition to validated and upcoming clinical use of electrical impedance tomography (EIT). EIT generates functional tomograms of the thorax for detection of changes in regional lung aeration. These images allow an intraindividual comparison of changes in regional lung function. Specifically, EIT aims to optimize ventilation therapy in patients with acute lung failure.PubMed: National Library of Medicine and the National Institutes of Health.Studies with the key words "electrical impedance tomography" since 1983.Qualitative and quantitative results of the studies.We summarize basic principles of the technique and subsequent analyzing methods, and g…

Functional magnetic resonance imaging of the lung

2003

MK801 blocks hypoxic blood-brain-barrier disruption and leukocyte adhesion.

2008

The aim of the present study was to examine the signaling pathways of hypoxia followed by reoxygenation (H/R)-induced disruption of the blood-brain-barrier (BBB) in a co-culture of astrocytes and brain endothelial cells (BEC) in vitro. We analyzed the possible stabilizing effect of MK801, a highly selective N-methyl-d-aspartate receptor (NMDAR) antagonist, on BBB integrity. Levels of reactive oxygen species (ROS), glutamate (Glut) release and monocyte adhesion were measured under normoxia and H/R. BBB integrity was monitored measuring the trans-endothelial electrical resistance (TEER). TEER values dropped under H/R conditions which was abolished by MK801. Glut release from astrocytes, but n…

Precise measurement of 1H 90° pulse in solid-state NMR spectroscopy for complex and heterogeneous molecular systems

2007

The 90 degrees pulse calibration is essential in NMR spectroscopy to prevent artefacts in the liquid state or to enhance cross-polarization efficiency in the solid state. We verified pulse-angle (PA) errors due to circuit impedances in solid-state NMR and suggested a possible solution to prevent the inconvenience of PA errors. The classic pulse sequences used to calibrate (1)H 90 degrees pulse lengths by direct detection of protons or by cross-polarization were modified in order to replace single (1)H pulses with (1)H pulse trains. Pulse trains were found to decrease the effect of PA imperfections in the calibration of basic pulses (i.e. 90 degrees and 180 degrees ) for a number of organic …

The healthy Nordic diet predicts muscle strength 10 years later in old women, but not old men

2017

Background a number of nutrients have been found to be associated with better muscle strength and mass; however, the role of the whole diet on muscle strength and mass remains still unknown. Objective to examine whether the healthy Nordic diet predicts muscle strength, and mass 10 years later among men and women. Methods about 1,072 participants belong to the Helsinki Birth Cohort Study, born 1934–44. Diet was assessed with a validated food-frequency questionnaire during 2001–04. The Nordic diet score (NDS) was calculated. The score included Nordic fruits, vegetables, cereals, ratio of polyunsaturated to saturated fatty acids, low-fat milk, fish, red meat, total fat and alcohol. Higher scor…

Nutritional predictors of mortality after discharge in elderly patients on a medical ward

2015

Background: Malnutrition in elderly inpatients hospitalized on medical wards is a significant public health concern. The aim of this study was to investigate nutritional markers as mortality predictors following discharge in hospitalized medical elderly patients. Materials and methods: This is a prospective observational cohort study with follow-up of 48 months. Two hundred and twenty-five individuals aged 60 and older admitted from the hospital emergency room in the past 48 h were investigated at the medical ward in the University hospital in Palermo (Italy). Anthropometric and clinical measurements, Mini-nutritional Assessment (MNA) questionnaire, bioelectrical (BIA) phase angle (PA), gri…