title: The diffusion approximation versus the telegraph equation for modeling solar energetic particle transport with adiabatic focusing. I. isotropic pitch-angle scattering

authors: Effenberger, Frederic

subjects: cosmic rays

abstract: The diffusion approximation to the Fokker-Planck equation is commonly used to model the transport of solar energetic particles in interplanetary space. In this study, we present exact analytical predictions of a higher order telegraph approximation for particle transport and compare them with the corresponding predictions of the diffusion approximation and numerical solutions of the full Fokker-Planck equation. We specifically investigate the role of the adiabatic focusing effect of a spatially varying magnetic field on an evolving particle distribution. Comparison of the analytical and numerical results shows that the telegraph approximation reproduces the particle intensity profiles much more accurately than does the diffusion approximation, especially when the focusing is strong. However, the telegraph approximation appears to offer no significant advantage over the diffusion approximation for calculating the particle anisotropy. The telegraph approximation can be a useful tool for describing both diffusive and wave-like aspects of the cosmic-ray transport.

text: The diffusion approximation versus the telegraph equation for modeling solar energetic particle transport with adiabatic focusing. I. isotropic pitch-angle scattering The diffusion approximation to the Fokker-Planck equation is commonly used to model the transport of solar energetic particles in interplanetary space. In this study, we present exact analytical predictions of a higher order telegraph approximation for particle transport and compare them with the corresponding predictions of the diffusion approximation and numerical solutions of the full Fokker-Planck equation. We specifically investigate the role of the adiabatic focusing effect of a spatially varying magnetic field on an evolving particle distribution. Comparison of the analytical and numerical results shows that the telegraph approximation reproduces the particle intensity profiles much more accurately than does the diffusion approximation, especially when the focusing is strong. However, the telegraph approximation appears to offer no significant advantage over the diffusion approximation for calculating the particle anisotropy. The telegraph approximation can be a useful tool for describing both diffusive and wave-like aspects of the cosmic-ray transport.

year: 2014

title: Development of extrudable hydrogels based on carboxymethyl cellulose–gelatin complex coacervates

authors: Gharanjig, Hamid

subjects: hydrogel

abstract: This study investigates the 3D extrusion printing of a carboxymethyl cellulose (CMC)–gelatin complex coacervate system. Various CMC–gelatin coacervate hydrogels were prepared and analyzed to achieve this goal. The impact of the CMC–gelatin ratio, pH, and total biopolymer concentration on coacervation formation and rheological properties was evaluated to characterize the printability of the samples. Turbidity results indicated that the molecular interactions between gelatin and CMC biopolymers are significantly pH-dependent, occurring within the range of pH 3.7 to pH 5.6 for the tested compositions. Confocal Laser Scanning Microscopy (CLSM) confirmed the presence of coacervates as spherical particles within the optimal coacervation range. Scanning electron microscopy micrographs supported the CLSM findings, revealing greater porosity within this optimal pH range. Rheological characterization demonstrated that all CMC–gelatin hydrogels exhibited pseudoplastic behavior, with an inverse correlation between increased coacervation and decreased shear viscosity. Additionally, the coacervates displayed lower tackiness compared to gelatin hydrogels, with the maximum tackiness normal force for various CMC–gelatin ratios ranging from 1 to 15 N, notably lower than the 29 N observed for gelatin hydrogels. Mixtures with CMC–gelatin ratios of 1:15 and 1:20 exhibited the best shear recovery behavior, maintaining higher strength after shear load. The maximum strength of the CMC–gelatin coacervate system was found at a biopolymer concentration of 6%. However, lower biopolymer content allowed for consistent extrusion. Importantly, all tested samples were successfully extruded at 22 ± 2 °C, with the 1:15 biopolymer ratio yielding the most consistent printed quality. Our research highlights the promise of the CMC–gelatin coacervate system for 3D printing applications, particularly in areas that demand precise material deposition and adjustable properties.

text: Development of extrudable hydrogels based on carboxymethyl cellulose–gelatin complex coacervates This study investigates the 3D extrusion printing of a carboxymethyl cellulose (CMC)–gelatin complex coacervate system. Various CMC–gelatin coacervate hydrogels were prepared and analyzed to achieve this goal. The impact of the CMC–gelatin ratio, pH, and total biopolymer concentration on coacervation formation and rheological properties was evaluated to characterize the printability of the samples. Turbidity results indicated that the molecular interactions between gelatin and CMC biopolymers are significantly pH-dependent, occurring within the range of pH 3.7 to pH 5.6 for the tested compositions. Confocal Laser Scanning Microscopy (CLSM) confirmed the presence of coacervates as spherical particles within the optimal coacervation range. Scanning electron microscopy micrographs supported the CLSM findings, revealing greater porosity within this optimal pH range. Rheological characterization demonstrated that all CMC–gelatin hydrogels exhibited pseudoplastic behavior, with an inverse correlation between increased coacervation and decreased shear viscosity. Additionally, the coacervates displayed lower tackiness compared to gelatin hydrogels, with the maximum tackiness normal force for various CMC–gelatin ratios ranging from 1 to 15 N, notably lower than the 29 N observed for gelatin hydrogels. Mixtures with CMC–gelatin ratios of 1:15 and 1:20 exhibited the best shear recovery behavior, maintaining higher strength after shear load. The maximum strength of the CMC–gelatin coacervate system was found at a biopolymer concentration of 6%. However, lower biopolymer content allowed for consistent extrusion. Importantly, all tested samples were successfully extruded at 22 ± 2 °C, with the 1:15 biopolymer ratio yielding the most consistent printed quality. Our research highlights the promise of the CMC–gelatin coacervate system for 3D printing applications, particularly in areas that demand precise material deposition and adjustable properties.

year: 2025-01-08

title: The display and conservation of taonga Māori - establishing culturally appropriate dislay and conversation facilities: Mahi Māreikura - a work in progress

authors: Whaanga, Hēmi

subjects: Māori art objects

abstract: This paper examines issues relating to the appropriate display and conservation of taonga Māori in the context of a discussion of the establishment of Mahi Māreikura, a room in the University of Waikato library that is dedicated primarily to the display and conservation of the collected taonga and works of the late Dr. Pei te Hurinui Jones and a collection of the work of his colleague and close relative, Professor Bruce Biggs.

text: The display and conservation of taonga Māori - establishing culturally appropriate dislay and conversation facilities: Mahi Māreikura - a work in progress This paper examines issues relating to the appropriate display and conservation of taonga Māori in the context of a discussion of the establishment of Mahi Māreikura, a room in the University of Waikato library that is dedicated primarily to the display and conservation of the collected taonga and works of the late Dr. Pei te Hurinui Jones and a collection of the work of his colleague and close relative, Professor Bruce Biggs.

year: 2006