RESUMEN
The global demand for products manufactured with carbon fibers (CFs) has increased in recent years; however, the waste generated at the end of the product lifetime has also increased. In this research, the impact of the addition of carbon nanotubes (CNTs) on the interlaminated resistance of recycled carbon fibers (RCFs) was studied. In this work, a recycling process of the composite material was applied via thermolysis to obtain the CFs, followed by the growth of CNTs on their surface using the Poptube technique. The recycling temperature were 500 °C and 700 °C; and ferrocene and polypyrrole were used to grow CNTs on CFs surface. CNTs were verified by Raman spectroscopy and scanning electron microscopy (SEM). Finally, to determine the interlaminar resistance, a double cantilever beam (DCB) test was performed. The results indicate that with Poptube technique, CNTs can be grown on RCFs using both impregnations. Thermolysis recycling process at 500 °C allowed CFs without resin residues and without visible damage. The DCB tests showed a decrease in the fracture resistance in mode I loading of 34.9% for the polypyrrole samples and 29.3% for the ferrocene samples compared with the virgin carbon fibers (VCFs) samples with a resistance of 1052.5 J/m2.
RESUMEN
A case of uterine Mullerian tumor in an adolescent is described. Surgical and clinical management is discussed, based on the experience gained by the analysis of cases described in the literature. A review of the different age groups, primary sites, surgical management and biological behavior of cases described in the literature is tabulated and analysed.
Asunto(s)
Neoplasias Endometriales/patología , Neoplasias de Células Germinales y Embrionarias/patología , Adolescente , Femenino , HumanosRESUMEN
Two cases of women with myasthenia gravis are presented. These women had three pregnancies followed by the authors, and description is made of clinical follow-up, therapeutic complications, termination of pregnancy, puerperal and perinatal outcome. A review of the literature is made due to the rarity of this condition and emphasis is given to the specialized knowledge required to adequately manage these cases. Myasthenia gravis, when associated to pregnancy, presents aspects that make it a high risk disease, decompensations of myasthenia being more common. Aspects relative to diagnosis and therapy of myasthenia in pregnancy and in the newly-born are reviewed, and considerations about anesthesia in the myasthenic pregnant woman.
Asunto(s)
Miastenia Gravis/complicaciones , Complicaciones del Embarazo , Adulto , Inhibidores de la Colinesterasa/uso terapéutico , Femenino , Humanos , Recién Nacido , Miastenia Gravis/congénito , Miastenia Gravis/tratamiento farmacológico , EmbarazoRESUMEN
A comparative study of the oxyntic cells of the stomach of Vertebrates is presented. A system of membranous tubules which is apparently inter-convertible with the luminal plasma membrane is described as an important structural feature in all classes. In all Vertebrates with the sole exception of Mammals, this system shares a common cell with the structures involved in the secretion of zymogen. In Mammals it becomes segregated into a specialized cell type, the parietal cell, characterized in addition by the presence of a long tortuous intracellular canaliculus, which serves as its secretory pole. The hypothesis is presented and discussed that the parietal cell is capable of achieving a higher efficiency in hydrochloric acid secretion by the existence of the intracellular canaliculus which makes the immediate surroundings of the secretory pole independent of the contents of the gastic lumen. In Birds (whose gastric glands do not possess parietal cells) a corresponding effect can be achieved only by complex structures such as the compound gastric glands. An explanation is hereby offered for the unique features of the Avian stomach.
Asunto(s)
Estómago/citología , Anfibios , Animales , Aves , Gatos , Diferenciación Celular , Membrana Celular/ultraestructura , Perros , Peces , Jugo Gástrico/metabolismo , Mucosa Gástrica/metabolismo , Humanos , Mamíferos , Microscopía Electrónica , Ratas , ReptilesRESUMEN
Gastric mucosa of an elasmobranch species was examined by electron microscope. The gastric glands contain one form of cell whose fine structure is similar to the cell that secretes both hydrochloric acid and pepsinogen of the amphibian gastric glands proper. The oxynticopeptic cells are characterized by: (a) a luminal surface with long projections of cytoplasm having dilatations in their thickness; (b) a tubulo-vesicular system in the apical cytoplasm; (c) a great number of mitochondria, some of which are of great length; (d) a well developed granular endoplasmic reticulum and a conspicuous Golgi apparatus; and (e) a large nucleus with a conspicuous nucleolus. A fourth part of the cells are binucleated. Physiological implications of some of these ultrastructural features are discussed.