2 results about "Relaxation rate" patented technology

Exemplary system, method and computer arrangement for determining rotational invariants, fiber orientations, and scalar parameters of fiber tracts (e.g., compartment fractions, which can relate to intra / extra-cellular space volumes; compartment diffusivities; relaxation rates; exchange rates between compartments; characteristics of structural disorder such as axonal beading) from a general diffusion MRI acquisition is described. For example, gradient directions may not necessarily be arranged in so-called shells, and an acquisition may vary spatially. Furthermore, each acquisition can be undersampled in the k-space. A procedure can also be included for receiving information related to the at least one image. Another procedure can be provided for decoupling tissue and protocol parameters based on a singular value decomposition. A further procedure can be provided for grouping singular vectors into multiplets based on symmetries. Still further procedures can be provided for forming rotational invariants and / or for a parameter estimation.

This invention discloses a multilayer composite membrane for invisible orthodontic appliances with low stress relaxation rate and its preparation method, belonging to the field of multilayer composite material technology. The membrane adopts a five-layer symmetrical structure, which includes an outer layer, a first relaxation spectrum bridging transition layer, an elastic core layer, a second relaxation spectrum bridging transition layer, and an inner layer. The outer and inner layers are made of rigid thermoplastic polyester material, the elastic core layer is made of medical-grade thermoplastic polyurethane elastomer, and the transition layer is made of a reactive blend of the above two polymers and an isocyanate-based reactive compatibilizer. The transition layer forms a covalent bond network in situ between the layers through reactive co-extrusion, so that the relaxation time spectrum between adjacent layers is continuously bridged, eliminating the additional viscoelastic dissipation caused by the redistribution of interlayer stress, and achieving a stress relaxation rate of no more than 15% in artificial saliva at 37°C for 24 hours.