Determining the blend level of mixtures of biodiesel with conventional diesel fuel by fiber-optic near-infrared spectroscopy and 1 H nuclear magnetic resonance spectroscopy

2001 ◽  
Vol 78 (10) ◽  
pp. 1025-1028 ◽  
Author(s):  
Gerhard Knothe
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Diesel Fuel ◽  
Near Infrared ◽  
Fiber Optic ◽  
Resonance Spectroscopy ◽  
Conventional Diesel Fuel

Simultaneous in vivo measurements of HbO2 saturation and PCr kinetics after exercise in normal humans

1994 ◽  
Vol 77 (1) ◽  
pp. 5-10 ◽  
Author(s):  
K. K. McCully ◽  
S. Iotti ◽  
K. Kendrick ◽  
Z. Wang ◽  
J. D. Posner ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Time Constant ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Plantar Flexion ◽  
Resonance Spectroscopy ◽  
Ph Values

Simultaneous measurements of phosphocreatine (PCr) and oxyhemoglobin (HbO2) saturation were made during recovery from exercise in calf muscles of five male subjects. PCr was measured using magnetic resonance spectroscopy in a 2.0-T 78-cm-bore magnet with a 9-cm-diam surface coil. Relative HbO2 saturation was measured as the difference in absorption of 750- and 850-nm light with use of near-infrared spectroscopy. The light source and detectors were 3 cm apart. Exercise consisted of isokinetic plantar flexion in a supine position. Two 5-min submaximal protocols were performed with PCr depletion to 60% of resting values and with pH values of > 7.0. Then two 1-min protocols of rapid plantar flexion were performed to deplete PCr values to 5–20% of resting values with pH values of < 6.8. Areas of PCr peaks (every 8 s) and HbO2 saturation (every 1 s) were fit to a monoexponential function, and a time constant was calculated. The PCr time constant was larger after maximal exercise (68.3 +/- 10.5 s) than after submaximal exercise (36.0 +/- 6.5 s), which is consistent with the effects of low pH on PCr recovery. HbO2 resaturation approximated submaximal PCr recovery and was not different between maximal (29.4 +/- 5.5 s) and submaximal (27.6 +/- 6.0 s) exercise. We conclude that magnetic resonance spectroscopy measurements of PCr recovery and near-infrared spectroscopy measurements of recovery of HbO2 saturation provide similar information as long as muscle pH remains near 7.0.

scholarly journals Computational modelling of the piglet brain to simulate near-infrared spectroscopy and magnetic resonance spectroscopy data collected during oxygen deprivation

2012 ◽  
Vol 9 (72) ◽  
pp. 1499-1509 ◽  
Author(s):  
Tracy Moroz ◽  
Murad Banaji ◽  
Nicola J. Robertson ◽  
Chris E. Cooper ◽  
Ilias Tachtsidis
Keyword(s):  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Redox State ◽  
Near Infrared ◽  
Lactate Concentration ◽  
Computational Modelling ◽  
Resonance Spectroscopy ◽  
Concentration Changes

We describe a computational model to simulate measurements from near-infrared spectroscopy (NIRS) and magnetic resonance spectroscopy (MRS) in the piglet brain. Piglets are often subjected to anoxic, hypoxic and ischaemic insults, as experimental models for human neonates. The model aims to help interpret measurements and increase understanding of physiological processes occurring during such insults. It is an extension of a previous model of circulation and mitochondrial metabolism. This was developed to predict NIRS measurements in the brains of healthy adults i.e. concentration changes of oxyhaemoglobin and deoxyhaemoglobin and redox state changes of cytochrome c oxidase (CCO). We altered and enhanced the model to apply to the anaesthetized piglet brain. It now includes metabolites measured by 31 P-MRS, namely phosphocreatine, inorganic phosphate and adenosine triphosphate (ATP). It also includes simple descriptions of glycolysis, lactate dynamics and the tricarboxylic acid (TCA) cycle. The model is described, and its simulations compared with existing measurements from piglets during anoxia. The NIRS and MRS measurements are predicted well, although this requires a reduction in blood pressure autoregulation. Predictions of the cerebral metabolic rate of oxygen consumption (CMRO 2 ) and lactate concentration, which were not measured, are given. Finally, the model is used to investigate hypotheses regarding changes in CCO redox state during anoxia.

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