Temperature Dependence of the Susceptibility of Fat Leads to Significant Temperature Errors in PRFS-based MR Thermometry

2010 ◽  
Author(s):  
S. M. Sprinkhuizen ◽  
M. K. Konings ◽  
C. J. G. Bakker ◽  
L. W. Bartels ◽  
Kullervo Hynynen ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Mr Thermometry ◽  
Significant Temperature ◽  
Temperature Errors

scholarly journals Temperature-induced tissue susceptibility changes lead to significant temperature errors in PRFS-based MR thermometry during thermal interventions

2010 ◽  
Vol 64 (5) ◽  
pp. 1360-1372 ◽  
Author(s):  
Sara M. Sprinkhuizen ◽  
Maurits K. Konings ◽  
Martijn J. van der Bom ◽  
Max A. Viergever ◽  
Chris J. G. Bakker ◽  
...  
Keyword(s):  
Mr Thermometry ◽  
Significant Temperature ◽  
Temperature Errors

scholarly journals The role of enzyme dynamics and tunnelling in catalysing hydride transfer: studies of distal mutants of dihydrofolate reductase

2006 ◽  
Vol 361 (1472) ◽  
pp. 1307-1315 ◽  
Author(s):  
Lin Wang ◽  
Nina M Goodey ◽  
Stephen J Benkovic ◽  
Amnon Kohen
Keyword(s):  
Temperature Dependence ◽  
Dihydrofolate Reductase ◽  
Isotope Effects ◽  
Hydride Transfer ◽  
Activation Parameters ◽  
Physical Nature ◽  
Enzyme Dynamics ◽  
Temperature Dependences ◽  
Donor Acceptor ◽  
Significant Temperature

Residues M42 and G121 of Escherichia coli dihydrofolate reductase ( ec DHFR) are on opposite sides of the catalytic centre (15 and 19 Å away from it, respectively). Theoretical studies have suggested that these distal residues might be part of a dynamics network coupled to the reaction catalysed at the active site. The ec DHFR mutant G121V has been extensively studied and appeared to have a significant effect on rate, but only a mild effect on the nature of H-transfer. The present work examines the effect of M42W on the physical nature of the catalysed hydride transfer step. Intrinsic kinetic isotope effects (KIEs), their temperature dependence and activation parameters were studied. The findings presented here are in accordance with the environmentally coupled hydrogen tunnelling. In contrast to the wild-type (WT), fluctuations of the donor–acceptor distance were required, leading to a significant temperature dependence of KIEs and deflated intercepts. A comparison of M42W and G121V to the WT enzyme revealed that the reduced rates, the inflated primary KIEs and their temperature dependences resulted from an imperfect potential surface pre-arrangement relative to the WT enzyme. Apparently, the coupling of the enzyme's dynamics to the reaction coordinate was altered by the mutation, supporting the models in which dynamics of the whole protein is coupled to its catalysed chemistry.

Thermotransport of Noble Metal Impurities in Lead

1972 ◽  
Vol 27 (1) ◽  
pp. 138-140 ◽  
Author(s):  
George A. Sullivan ◽  
Sune Larsson ◽  
Per T. Thernquist
Keyword(s):  
Steady State ◽  
Temperature Dependence ◽  
Noble Metal ◽  
Temperature Gradients ◽  
Electronic Contribution ◽  
Kcal Mole ◽  
Cold Side ◽  
Heat Of Transport ◽  
Metal Impurities ◽  
Significant Temperature

Abstract Steady-state distributions of Au, Ag and Cu tracers in Pb wafers subjected to temperature gradients have been determined. The effective heats of transport were + 5.8 ± 1.1 for Ag, - 0.5 ± 0.3 for Au, and of the order of + 35 for Cu (all in kcal/mole, positive values denoting the impurity migrating to the cold side of the Pb wafer). No significant temperature dependence of the heats of transport could be detected. The results are difficult to reconcile with existing theories of the intrinsic and electronic contribution to the heat of transport.

scholarly journals DEPENDENCE OF THE COSMIC MUON FLUX ON ATMOSPHERIC PRESSURE AND TEMPERATURE

2007 ◽  
Vol 14 (1) ◽  
pp. 56
Author(s):  
PHAM NGOC DIEP ◽  
PHAM THI TUYET NHUNG ◽  
PHAM NGOC DINH ◽  
NGUYEN HAI DUONG ◽  
PIERRE DARRIULAT ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Atmospheric Pressure ◽  
Muon Flux ◽  
Ground Temperature ◽  
Cosmic Muon ◽  
Significant Temperature ◽  
Temperature And Pressure

The dependence upon atmospheric pressure of the cosmic muon flux in Hanoi has been measured to be -1.47± 0.50 permil per mbar in agreement with expectation from a naive estimate. The dependence over ground temperature is observed to largely reflect the correlation existing between temperature and pressure. Once the effect of this correlation is removed a smaller, barely significant temperature dependence of -0.57± 0.34 permil per °C subsists.

Temperature dependence of charge carrier ranges in stabilized a-Se photoconductors

2014 ◽  
Vol 92 (7/8) ◽  
pp. 634-640 ◽  
Author(s):  
Bud Fogal ◽  
Safa Kasap
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Collection Efficiency ◽  
Activation Energies ◽  
Charge Collection Efficiency ◽  
X Ray ◽  
Thermally Activated ◽  
Deep Traps ◽  
Significant Temperature ◽  
Experimental Errors

Using time-of-flight (TOF) and interrupted-field TOF we have measured the electron and hole drift mobilities, μe and μh, lifetimes, τe and τh, and hence carrier ranges, μeτe and μhτh, in stabilized a-Se as a function of temperature from −25 to 45 °C. Above room temperature, μeτe and μhτh show a slight increase with temperature and peak around 31 and 35 °C, respectively. The μeτe at 35 °C and μhτh at 40 °C are approximately the same as room temperature values. Below room temperature, down to −25 °C, both μe and μh decrease with decreasing temperature with activation energies Eμe and Eμh that are 0.38 and 0.21 eV. The electron and hole lifetimes, τe and τh, are also thermally activated but they increase with decreasing temperature with activation energies Eτe and Eτh that are 0.31 and 0.18 eV. These are quite close to corresponding activation energies for the drift mobilities within experimental errors. The electron and hole ranges, μeτe and μhτh, therefore exhibit only a weak temperature dependence, both increase slightly with temperature. These observations are consistent with shallow trap controlled transport in the presence of a set of deep traps. The X-ray sensitivity of a photoconductor, among other factors, depends on the charge collection efficiency, which depends on electron and hole ranges, μeτe and μhτh. Because these carrier ranges do not show any significant temperature dependence, one can conclude that the X-ray sensitivity of stabilized a-Se over the temperature range from −25 to 40 °C should not be affected by changes in the collection efficiency.

Kinetic Energy Release and Energy Partitioning During the Ionic Fragmentation in Metastable Ions

1983 ◽  
Vol 38 (5) ◽  
pp. 524-527
Author(s):  
F. H. Abd El-Kader ◽  
M. S. Abd El-Fattah
Keyword(s):  
Kinetic Energy ◽  
Temperature Dependence ◽  
Kinetic Energy Release ◽  
Molecular Ions ◽  
Energy Partitioning ◽  
Unimolecular Decomposition ◽  
Centrifugal Barrier ◽  
Metastable Ions ◽  
Significant Temperature ◽  
Ionic Fragmentation

The kinetic energy released in the unimolecular decomposition of some metastable transitions has been investigated. It was found to have a significant temperature dependence in cases of H‘ loss from molecular ions. This is attributed to the tunelling of H• atom through the centrifugal barrier.The activation energies of the reverse reactions “εr≠” and the kinetic energy released “TB” have been determined for the loss of H• from acetonitrile and elimination of HCN from benzonitrile. The partitioning energy quotients q=TB/εr≠ are found = 0.91 and 0.58 for acetonitrile and benzonitrile respectively.

scholarly journals DEPENDENCE OF THE COSMIC MUON FLUX ON ATMOSPHERIC PRESSURE AND TEMPERATURE

2007 ◽  
Vol 14 (1) ◽  
pp. 56
Author(s):  
PHAM NGOC DIEP ◽  
PHAM THI TUYET NHUNG ◽  
PHAM NGOC DINH ◽  
NGUYEN HAI DUONG ◽  
PIERRE DARRIULAT ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Atmospheric Pressure ◽  
Muon Flux ◽  
Ground Temperature ◽  
Cosmic Muon ◽  
Significant Temperature ◽  
Temperature And Pressure

The dependence upon atmospheric pressure of the cosmic muon flux in Hanoi has been measured to be -1.47± 0.50 permil per mbar in agreement with expectation from a naive estimate. The dependence over ground temperature is observed to largely reflect the correlation existing between temperature and pressure. Once the effect of this correlation is removed a smaller, barely significant temperature dependence of -0.57± 0.34 permil per °C subsists.

Significant Temperature Dependence of the Isosteric Heats of Adsorption of Gases in Zeolites Demonstrated by Experiments and Molecular Simulations

2019 ◽  
Vol 123 (33) ◽  
pp. 20405-20412 ◽  
Author(s):  
Alexander S. Hyla ◽  
Hanjun Fang ◽  
Salah Eddine Boulfelfel ◽  
Giovanni Muraro ◽  
Charanjit Paur ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Molecular Simulations ◽  
Heats Of Adsorption ◽  
Significant Temperature ◽  
Adsorption Of Gases

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

Temperature Dependence of Magnetic Domains and Wall Structures

1972 ◽  
Vol 30 ◽  
pp. 496-497
Author(s):  
Sonoko Tsukahara ◽  
Tadami Taoka ◽  
Hisao Nishizawa
Keyword(s):  
Temperature Dependence ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Iron Film ◽  
Objective Lens ◽  
Lorentz Microscopy ◽  
Domain Structures ◽  
Wall Structures ◽  
Crystal Films ◽  
Metallurgical Structure

The high voltage Lorentz microscopy was successfully used to observe changes with temperature; of domain structures and metallurgical structures in an iron film set on the hot stage combined with a goniometer. The microscope used was the JEM-1000 EM which was operated with the objective lens current cut off to eliminate the magnetic field in the specimen position. Single crystal films with an (001) plane were prepared by the epitaxial growth of evaporated iron on a cleaved (001) plane of a rocksalt substrate. They had a uniform thickness from 1000 to 7000 Å.The figure shows the temperature dependence of magnetic domain structure with its corresponding deflection pattern and metallurgical structure observed in a 4500 Å iron film. In general, with increase of temperature, the straight domain walls decrease in their width (at 400°C), curve in an iregular shape (600°C) and then vanish (790°C). The ripple structures with cross-tie walls are observed below the Curie temperature.

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