Explaining the abnormally high flow activation energy of thermoplastic polyurethanes

Abstract

We fabricate a biometric laser fiber synaptic sensor to transmit information from one neuron cell to the other by an optical way. The optical synapse is constructed on the base of an erbium-doped fiber laser, whose pumped diode current is driven by a pre-synaptic FitzHugh-Nagumo electronic neuron, and the laser output controls a post-synaptic FitzHugh-Nagumo electronic neuron. The implemented laser synapse displays very rich dynamics, including fixed points, periodic orbits with different frequency-locking ratios and chaos. These regimes can be beneficial for efficient biorobotics, where behavioral flexibility subserved by synaptic connectivity is a challenge. " 2013 by the authors; licensee MDPI, Basel, Switzerland.",,,,,,"10.3390/s131217322",,,"http://hdl.handle.net/20.500.12104/41389","http://www.scopus.com/inward/record.url?eid=2-s2.0-84890494163&partnerID=40&md5=4794c8f5ec03950f072a266bde299eed",,,,,,"12",,"Sensors (Switzerland)",,"17322

17331",,"13",,"Scopus

WOS",,,,,,"Artificial intelligence; Biorobotics; Electronic circuit; Fiber laser; Neuroengineering; Neuron; Pump modulation; Synapse",,,,,,"Experimental implementation of a biometric laser synaptic sensor",,"Article" "43157","123456789/35008",,"Castellanos, M.A.R., Instituto Dermatológico de Jalisco Dr. José Barba Rubio, Mexico; Padilla, L.M.M.; Torres, M.M.H., Instituto Dermatológico de Jalisco Dr. José Barba Rubio, Mexico; Gómez, E.V., Hospital Civil de Guadalajara Juan I Menchaca, Mexico; Borrego, J.A.B., Clínica de Dermatología, Universidad de Guadalajara, Mexico",,"Castellanos, M.A.R.

Padilla, L.M.M.

Torres, M.M.H.

Gomez, E.V.

Borrego, J.A.B.",,"2012",,"Background: Osteocartilaginous' tumors -exostosis and subungual osteochondroma- are benign and rare tumors, which are more frequent in women in the second and third decades of life. Objective: To evaluate the clinical, epidemiological and histological subungual tumors of osteocartilaginous origin at Dermatological Institute of Jalisco Dr. Jose Barba Rubio, Jalisco, Mexico. Material and methods: We performed a retrospective study from January 1st, 1987 to December 31st, 2001, which included reports of patients with subungual osteocartilaginous tumor, exostosis or osteocondroma. We collected the following variables: frequency, age, gender, location and presence of hyaline cartilage and/or fibrocartilage attached to bone. Results: There were 199 cases of subungual osteocartilaginous tumors; 139 of them were women (70%), 58 were men (29%) and 2 were undetermined (1%). The average age of patients was 19 14 years old, predominantly between 10 and 19 years of age (59%). The condition was frequent in the first finger of the foot, with 71%. Fibrocartilage was observed in 98%, in 18% was exclusive and only 2% of the cases showed pure hyaline cartilage. In all cases the range of evolution time was from three weeks to six months. Conclusion: Osteocartilaginous tumors are uncommon, most lesions showed both cartilages in different proportions.",,,,,,,,,"http://hdl.handle.net/20.500.12104/41378","http://www.scopus.com/inward/record.url?eid=2-s2.0-84870007085&partnerID=40&md5=8fee7c7294f713c807119fca90a440a0",,,,,,"4",,"Dermatologia Revista Mexicana",,"236

240",,"56",,"Scopus",,,,,,"Osteocartilaginous subungual tumors; Subungual exostosis; Subungual osteochondroma",,,,,,"Exostosis and subungual osteochondroma. Clinical, epidemiological and histological characteristics in Mexican patients [Osteocondroma y exostosis subungueal. Características clúnicoepidemiológicas e histológicas en pacientes mexicanos]",,"Article" "43177","123456789/35008",,"Lu, Q.-W., Department of Chemical Engineering, University of Minnesota, Minneapolis, MN 55455-0431, United States; Hernandez-Hernandez, M.E., Department of Chemical Engineering, University of Minnesota, Minneapolis, MN 55455-0431, United States, Universidad de Guadalajara, Departamento de Ingenieria Quimica, Guadalajara, Jalisco 44430, Mexico; Macosko, C.W., Department of Chemical Engineering, University of Minnesota, Minneapolis, MN 55455-0431, United States",,"Lu, Q.-W.

Hernandez-Hernandez, M.E.

Macosko, C.W.",,"2003",,"The rheological properties of a thermoplastic polyurethane (TPU) were studied at small and large deformation via three different types of rheometry: dynamic shear, capillary, and torque (an instrumented batch mixer). The effect of degradation during TPU processing on the melt viscosity was investigated and several factors, such as temperature, time, shear stress, and flow type that may affect the degradation were studied. Apparent activation energy of flow (Ea) was determined to be 328 kJ/mol, much larger than expected. A simple model was derived to describe the relationship of molecular weight and thermal dissociation of urethane linkages. Contributions of flow and the degradation reaction of TPU to overall activation energy were found to be additive: Ea = E? + 1.7?Hdeg. True activation energy of flow (E?) was estimated to be 144 kJ/mol. While the high apparent flow activation energies in dynamic shear and capillary rheometry can be explained by simple thermal degradation, melt viscosities interpreted from the instrumented batch mixer showed a much lower apparent activation energy (186 kJ/mol). This low value may be due to a combination of effects: errors in the relation between viscosity and mixer torque for TPU, side reactions resulting from air exposure, high stress level during the melting, and extensional stresses. " 2003 Elsevier Science Ltd. All rights reserved.