RESUMO
Recently, the automobile industry has demanded weight reduction, so research on materials is being actively conducted. Among this research, carbon fiber-reinforced composite materials are being studied a lot in the automobile industry due to their excellent mechanical properties, chemical resistance, and heat resistance. However, carbon fiber-reinforced composite materials have disadvantages, in that they are not free from color selection, and have weak interfacial bonding strength. In this study, a colored epoxy resin was prepared by mixing epoxy-which is a thermosetting resin according to the pigment concentration (0.1, 0.3, 0.5, 1.0 wt%)-and curing shrinkage. Thermal expansion characteristics were analyzed and the concentration of 0.5 wt% pigment showed the lowest shrinkage and thermal expansion characteristics. In addition, to measure the interfacial shear strength (IFSS) of the carbon fiber and the colored epoxy resin, the IFSS was obtained by performing a microdroplet debonding test, and the strength of the pigment concentration of 0.5 wt% was reduced to a relatively low level. Through these experiments, it was determined that an epoxy resin in which 0.5 wt% pigment is mixed is the optimal condition. Finally, using the composite material modeling software (Digimat 2020.0), the representative volume element (RVE) of the meso-scale was set, and interfacial properties of carbon fibers and colored epoxy resins were analyzed by interworking with general-purpose finite element analysis software (Abaqus CAE).
RESUMO
Cytomegalovirus (CMV) infections are usually diagnosed in immunocompromised patients. A 74-year-old male without any significant medical history visited our center because of abdominal pain and diarrhea which began about a month ago. Abdominal computed tomography revealed segmental enhanced bowel wall thickening on jejunum and single-balloon enteroscopy showed multiple geographic shaped ulcerations covered with exudates on proximal jejunum. Biopsy samples taken during endoscopic examination demonstrated necrotic fibrinopurulent tissue debris and benign ulcer. Nested-PCR analysis of CMV DNA from jejunal tissue was positive. The patient was finally diagnosed with CMV jejunitis and was treated by intravenous ganciclovir for 14 days after which, abdominal pain and diarrhea improved. Our case shows that CMV jejunitis can occur in an immunocompetent adult as multiple jejunal ulcers which can be diagnosed using a single-balloon enteroscope.