Investigation of water dynamic behaviour in poly(HEMA) and poly(HEMA-co-DHPMA) hydrogels by proton T2 relaxation time and self-diffusion coefficient n.m.r. measurements

The diffusive properties of mesophilic methanogenic granular sludge have been studied using diffusion analysis by relaxation time separated pulsed field gradient nuclear magnetic resonance (DARTS PFG NMR) spectroscopy. NMR measurements were performed at 22°C with 10 ml granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Spin-spin relaxation (T2) time measurements indicate that three 1H populations can be distinguished in methanogenic granular sludge beds, corresponding to water in three different environments. The T2 relaxation time measurements clearly differentiate the extragranular water (T2 ≈ 1000 ms) from the water present in the granular matrix (T2 = 40-100 ms) and bacterial cell associated water (T2 = 10-15 ms). Self-diffusion coefficient measurements at 22°C of the different 1H-water populations as the tracer show that methanogenic granular sludge does not contain one unique diffusion coefficient. The observed distribution of self-diffusion coefficients varies between 1.1 × 10−9 m2/s (bacterial cell associated water) and 2.1 × 10−9 m2/s (matrix associated water).

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Changes in the apparent diffusion coefficient of water and T2 relaxation time in gerbil hippocampus after mild ischemia

Neuroreport ◽

10.1097/00001756-200010200-00014 ◽

2000 ◽

Vol 11 (15) ◽

pp. 3333-3336 ◽

Cited By ~ 3

Author(s):

Lidong Zhu ◽

Nobuhito Saito ◽

Osamu Abe ◽

Toshiyuki Okubo ◽

Haruyasu Yamada ◽

...

Keyword(s):

Diffusion Coefficient ◽

Relaxation Time ◽

Apparent Diffusion Coefficient ◽

T2 Relaxation Time ◽

T2 Relaxation ◽

Apparent Diffusion

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Determining T2 relaxation time and stroke onset relationship in ischaemic stroke within apparent diffusion coefficient-defined lesions. A user-independent method for quantifying the impact of stroke in the human brain

Biomedical Spectroscopy and Imaging ◽

10.3233/bsi-190185 ◽

2019 ◽

Vol 8 (1-2) ◽

pp. 11-28 ◽

Cited By ~ 1

Author(s):

Michael J. Knight ◽

Robin A. Damion ◽

Bryony L. McGarry ◽

Rose Bosnell ◽

Kimmo T. Jokivarsi ◽

...

Keyword(s):

Diffusion Coefficient ◽

Relaxation Time ◽

Apparent Diffusion Coefficient ◽

Human Brain ◽

Ischaemic Stroke ◽

Independent Method ◽

T2 Relaxation Time ◽

T2 Relaxation ◽

Apparent Diffusion ◽

The Impact

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Diffusional Properties of Methanogenic Granular Sludge: 1H NMR Characterization

Applied and Environmental Microbiology ◽

10.1128/aem.69.11.6644-6649.2003 ◽

2003 ◽

Vol 69 (11) ◽

pp. 6644-6649 ◽

Cited By ~ 19

Author(s):

Piet N. L. Lens ◽

Rakel Gastesi ◽

Frank Vergeldt ◽

Adriaan C. van Aelst ◽

Antonio G. Pisabarro ◽

...

Keyword(s):

Diffusion Coefficient ◽

Relaxation Time ◽

Nmr Spectroscopy ◽

Diffusion Coefficients ◽

Metal Sulfide ◽

Free Water ◽

Granular Sludge ◽

Self Diffusion ◽

Nmr Characterization ◽

Self Diffusion Coefficient

ABSTRACT The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H2O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H2O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl2 did not affect the H2O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors.

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Secondary Reduction in the Apparent Diffusion Coefficient of Water, Increase in Cerebral Blood Volume, and Delayed Neuronal Death after Middle Cerebral Artery Occlusion and Early Reperfusion in the Rat

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/00004647-199912000-00009 ◽

1999 ◽

Vol 19 (12) ◽

pp. 1354-1364 ◽

Cited By ~ 61

Author(s):

Menno van Lookeren Campagne ◽

G. Roger Thomas ◽

Harold Thibodeaux ◽

James T. Palmer ◽

Simon P. Williams ◽

...

Keyword(s):

Diffusion Coefficient ◽

Relaxation Time ◽

Cerebral Blood Volume ◽

Vascular Occlusion ◽

T2 Relaxation Time ◽

T2 Relaxation ◽

Early Reperfusion ◽

Occlusion Time ◽

Contrast Enhanced ◽

Apparent Diffusion

It has been reported recently that very delayed damage can occur as a result of focal cerebral ischemia induced by vascular occlusion of short duration. With use of diffusion-, T2-, and contrast-enhanced dynamic magnetic resonance imaging (MRI) techniques, the occlusion time dependence together with the temporal profile for this delayed response in a rat model of transient focal cortical ischemia have been established. The distal branch of the middle cerebral artery was occluded for 20, 30, 45, or 90 minutes. Twenty minutes of vascular occlusion with reperfusion exhibited no significant mean change in either the apparent diffusion coefficient of water (ADC) or the T2 relaxation time at 6, 24, 48, or 72 hours after reperfusion ( P = 0.97 and 0.70, respectively). Ninety minutes of ischemia caused dramatic tissue injury at 6 hours, as indicated by an increase in T2 relaxation times to 135% of the contralateral values ( P < 0.01). However, at intermediate periods of ischemia (30 to 45 minutes), complete reversal of the ADC was seen at 6 hours after reperfusion but was followed by a secondary decline over time, such that a 25% reduction in tissue ADC was seen at 24 as compared with 6 hours ( P < 0.02). This secondary response was accompanied by an increase in cerebral blood volume (CBV), as shown by contrast-enhanced dynamic MRI (120% of contralateral values; P < 0.001), an increase in T2 relaxation time (132%; P < 0.01), together with clear morphological signs of cell death. By day 18, the mean volume of missing cortical tissue measured with high-resolution MRI in animals occluded for 30 and 45 minutes was 50% smaller than that in 90-minute occluded animals ( P < 0.005). These data show that ultimate infarct size is reduced after early reperfusion and is occlusion time dependent. The early tissue recovery that is seen with intermediate occlusion times can be followed by cell death, which has a delayed onset and is accompanied by an increase in CBV.

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