نتایج جستجو برای: axial diffusion
تعداد نتایج: 209231 فیلتر نتایج به سال:
In this study, the ignitability characteristics affected by an oxygen coaxial flow diluted with inert gases (nitrogen and helium) were experimentally investigated using Jet A1 diffusion flame configurations. As molar concentration of supplied to increased, dilution gas decreased, which drastically lowered measured minimum ignition energy. When only was without gas, most easily observed, thereby...
The authors report the utility of diffusion tensor tractography in demonstrating the partially severed spinal cord tracts on one side with normal, intact, distally traceable tracts on the opposite side in a patient with posttraumatic Brown Sequard syndrome. A 30-year-old man presented with typical clinical features of a hemisection injury of the thoracic spinal cord, 2 months after he had susta...
Diffusion-weighted imaging (DWI) quantifies water molecule diffusion within tissues and is becoming an increasingly used technique. However, it is very challenging as correct quantification depends on many different factors, ranging from acquisition parameters to a long pipeline of image processing. In this work, we investigated the influence of voxel geometry on diffusion analysis, comparing d...
A novel mathematical model for the water transport into and drug release from hydroxypropyl methylcellulose (HPMC) tablets is presented. Fick's second law of diffusion is used to describe the mass transfer processes in the three-component system drug/polymer/water. Numerical solutions of the respective set of partial differential equations are provided, considering axial and radial diffusion wi...
Competitive adsorption of furfural and phenolic compounds onto activated carbon in fixed bed column.
For a multicomponent competitive adsorption of furfural and phenolic compounds, a mathematical model was builtto describe the mass transfer kinetics in a fixed bed column with activated carbon. The effects of competitive adsorption equilibrium constant, axial dispersion, external mass transfer, and intraparticle diffusion resistance on the breakthrough curve were studied for weakly adsorbed com...
Recent studies in rodents have demonstrated that diffusion imaging is highly sensitive to differences in myelination. These studies suggest that demyelination/dysmyelination cause increases in the radial diffusivity from diffusion tensor imaging (DTI) measurements and decreases in the restricted diffusion component from high b-value diffusion-weighted imaging experiments. In this study, the sha...
OBJECTIVE Many diffusion tensor imaging (DTI) studies of the corpus callosum (CC) have been performed with a relatively thick slice thickness in the axial plane, which may result in underestimating the fractional anisotropy (FA) of the CC due to a partial volume effect. We hypothesized that the FA of the CC can be more accurately measured by using mid-sagittal DTI. We compared the FA values of ...
Diffusion tensor imaging (DTI) is a promising biomarker of spinal cord injury (SCI). In the acute aftermath, DTI in SCI animal models consistently demonstrates high sensitivity and prognostic performance, yet translation of DTI to acute human SCI has been limited. In addition to technical challenges, interpretation of the resulting metrics is ambiguous, with contributions in the acute setting f...
Introduction Diffusion tensor imaging (DTI) is widely used for the study of white matter (WM) diseases and fractional anisotropy (FA) is commonly used as a measure of WM integrity. However, FA is also highly sensitive to such factors as non-Gaussian diffusion, crossing fibers and imaging noise, which may degrade its specificity. It has recently been proposed that the axial diffusivity (D//) of ...
OBJECTIVE This study investigated white matter integrity in patients with amnestic mild cognitive impairment by diffusion tensor imaging. METHODS A total of 83 patients with amnestic mild cognitive impairment and 85 elderly healthy controls underwent neuropsychological testing and a diffusion tensor imaging scan. Whole-brain white matter data were parcellated into 50 regions based on the anat...
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