Electron paramagnetic resonance and dynamic nuclear polarization of char suspensions: surface science and oximetry

Clarkson, R. B.; Odintsov, B. M.; Ceroke, P.J.; r-Larsen, J H Ardenkjæ; Fruianu, Michelina; Belford, R. Linn

doi:10.1088/0031-9155/43/7/012

Cited by 57 publications

(55 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…139 The mechanism of oxygen response has been studied in several synthesized chars. The results suggest that these compounds contain two types of paramagnetic centers (PC), 140,141 differing by their distance to the adsorbed oxygen molecules. Each type of PC is characterized by its own oxygen sensitivity and EPR linewidth.…”

Section: Principles Of Epr Oximetrymentioning

confidence: 99%

“…139 While any organic material can be charred, the most useful materials appear to be those derived from carbohydrates and woody plants. 140,173 The controlled production of these materials is very complex because the response of the paramagnetic centers to pO 2 is extremely sensitive to the conditions under which the charring takes place. 140,177,178 On the other hand, this has some beneficial aspects.…”

Section: Particulate Paramagnetic Materialsmentioning

confidence: 99%

“…140,173 The controlled production of these materials is very complex because the response of the paramagnetic centers to pO 2 is extremely sensitive to the conditions under which the charring takes place. 140,177,178 On the other hand, this has some beneficial aspects. For example, the range of sensitivity can be adapted to specific needs such as high sensitivity at low pO 2 or modest sensitivity over a very large range of pO 2 .…”

Section: Particulate Paramagnetic Materialsmentioning

confidence: 99%

See 2 more Smart Citations

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

2004

View full text Add to dashboard Cite

This review paper attempts to provide an overview of the principles and techniques that are often termed electron paramagnetic resonance (EPR) oximetry. The paper discusses the potential of such methods and illustrates they have been successfully applied to measure oxygen tension, an essential parameter of the tumor microenvironment. To help the reader understand the motivation for carrying out these measurements, the importance of tumor hypoxia is first discussed: the basic issues of why a tumor is hypoxic, why these hypoxic microenvironments promote processes driving malignant progression and why hypoxia dramatically influences the response of tumors to cytotoxic treatments will be explained. The different methods that have been used to estimate the oxygenation in tumors will be reviewed. To introduce the basics of EPR oximetry, the specificity of in vivo EPR will be discussed by comparing this technique with NMR and MRI. The different types of paramagnetic oxygen sensors will be presented, as well as the methods for recording the information (EPR spectroscopy, EPR imaging, dynamic nuclear polarization). Several applications of EPR for characterizing tumor oxygenation will be illustrated, with a special emphasis on pharmacological interventions that modulate the tumor microenvironment. Finally, the challenges for transposing the method into the clinic will also be discussed.

show abstract

Section: Principles Of Epr Oximetrymentioning

confidence: 99%

Section: Particulate Paramagnetic Materialsmentioning

confidence: 99%

Section: Particulate Paramagnetic Materialsmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

2004

View full text Add to dashboard Cite

show abstract

“…Figure 4 shows oxygen mapping of a tumor-bearing anesthetized mouse obtained by pulsed EPRI using PDT nitroxide (Scheme 1) (Hyodo et al, 2009). Strong heterogeneity of tumor oxygenation and significant hypoxic regions (<10 mmHg) EPR applications of other oxygen-sensitive paramagnetic materials include soluble trityl radicals Bobko et al, 2009) and particulate probes such as lithium phthalocyanine particles (Liu et al, 1993;Presley et al, 2006) and carbonaceous materials (chars, coals, carbon blacks) (Clarkson et al, 1998). It should be noted that particulate probes such as lithium phthalocyanine and synthetic char are suitable for measurements of oxygen partial pressure in place of implantation whereas soluble probes such as nitroxides and trityl compounds more suitable for imaging experiments.…”

Section: Epr-based Oximetric Applications Of the Nitroxidesmentioning

confidence: 99%

In vivo Spectroscopy and Imaging of Nitroxide Probes

Khramtsov¹

2012

Nitroxides - Theory, Experiment and Applications

View full text Add to dashboard Cite

“…Six individual project reports to the DOE described the instrumentation, techniques, theory, and typical results. [1][2][3][4][5][6] Sixteen peerreviewed articles [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] contain details and discussions of parts of this work. These reports describe the first observations of solid-liquid electron spin density transfer, showing a transient chemical interaction between water molecules and particulate surfaces in an aqueous slurry of carbonaceous char particles by a proton pulsed Dynamic Nuclear Polarization (DNP) technique at low magnetic field.…”

Section: Executive Summarymentioning

confidence: 99%

Coal and Char Studies by Advanced Emr Techniques

Belford¹,

Clarkson²,

Nilges³

et al. 2001

View full text Add to dashboard Cite

Advanced electronic magnetic resonance (EMR) as well as nuclear magnetic resonance (NMR) methods have been used to examine properties of coals, chars, and molecular species related to constituents of coal. During the span of this grant, progress was made on construction and applications to coals and chars of two high frequency EMR systems particularly appropriate for such studies -48 GHz and 95 GHz electron magnetic resonance spectrometer, on new low-frequency dynamic nuclear polarization (DNP) experiments to examine the interaction between water and the surfaces of suspended char particulates in slurries, and on a variety of proton nuclear magnetic resonance (NMR) techniques to measure characteristics of the water directly in contact with the surfaces and pore spaces of carbonaceous particulates. EXECUTIVE SUMMARYThe main advanced magnetic resonance methods employed over the period of this project were (1) W-band (100 GHz) electronic magnetic resonance (EMR) spectroscopy to provide an analytical tool to discriminate among very similar chemical species that are constituents of coals and closely related materials such as chars, (2) construction of a U-band (50 GHz) EMR spectrometer to aid such analysis by filling the wide gap between W-band and the lower available frequencies, (3) very low frequency pulsed dynamic nuclear polarization (DNP) spectroscopy for study of the interfaces between coal-like particles and the water medium in which they are suspended, and (4) a variety of proton nuclear magnetic resonance (NMR) techniques to measure characteristics of the water in contact with particle surfaces and pore spaces.This project was carried out over a forty-two month period. Six individual project reports to the DOE described the instrumentation, techniques, theory, and typical results.1-6 Sixteen peerreviewed articles 7-22 contain details and discussions of parts of this work. These reports describe the first observations of solid-liquid electron spin density transfer, showing a transient chemical interaction between water molecules and particulate surfaces in an aqueous slurry of carbonaceous char particles by a proton pulsed Dynamic Nuclear Polarization (DNP) technique at low magnetic field. In a second study, by use of Fourier Transform PulsedField-Gradient spin-echo NMR spectroscopy several self-diffusion coefficients were obtained in aqueous char suspensions corresponding to different mobilities of water molecules in the porous structures. It was concluded that the short-range nuclear-electronic interactions in pore space have the dominant effect on DNP enhancement in char suspensions. In another study, a strong particle size influence on NMR transverse proton relaxation in aqueous suspensions of these newly synthesized chars was found.Multifrequency EMR spectroscopy can be a powerful tool in understanding details of the chemical species present in native and processed coals, coal constituents, and synthetic carbonaceous materials like chars. High frequency EMR is especially informative because of...

show abstract

Electron paramagnetic resonance and dynamic nuclear polarization of char suspensions: surface science and oximetry

Cited by 57 publications

References 23 publications

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

In vivo Spectroscopy and Imaging of Nitroxide Probes

Coal and Char Studies by Advanced Emr Techniques

Contact Info

Product

Resources

About