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Down the Rabbit Hole-Considerations for Ingested Foreign Bodies
Brown, Jerry,Kidder, Molly,Fabbrini, Abigail,deVries, Jonathan,Robertson, Jason,Chandler, Nicole,Wilsey, Michael The Korean Society of Pediatric Gastroenterology 2019 Pediatric gastroenterology, hepatology & nutrition Vol.22 No.6
We report the case of a seven-year-old boy with an ingested foreign body, which was retained within the appendix for a known duration of ten months, ultimately requiring appendectomy. The ingested foreign body was incidentally discovered by abdominal x-ray at an emergency room visit for constipation. Despite four bowel cleanouts, subsequent x-rays showed persistence of the foreign body in the right lower quadrant. While the patient did not have signs or symptoms of acute appendicitis, laparoscopic appendectomy was performed due to the risk of this foreign body causing appendicitis in the future. A small metallic object was found within the appendix upon removal. This case highlights the unique challenge presented by foreign body ingestions in non-verbal or developmentally challenged children and the importance of further diagnostic workup when concerns arise for potential retained foreign bodies.
Jong-Hyun Kim,권동준,K. Lawrence DeVries,Joung-ManPark 한국섬유공학회 2022 Fibers and polymers Vol.23 No.6
This study improved the interfacial and mechanical properties of carbon fiber (CF) reinforced 5-ethylidene-2-norbornene (ENB) composites using the Ru catalyst coating method on CF for vacuum-assisted resin transfer molding(VARTM). Generally, the Ru catalyst added ENB was polymerized using mixing two materials. The interfacial andmechanical properties of the composites containing Ru catalyst coated carbon fabric were higher than those in which Rucatalyst was mixed in the ENB before being embedded in the CF fabric. It can be mainly due to the uniform or randomdispersion of Ru catalyst by two different manufacturing processes. The interfacial properties determined using themicrodroplet test, e.g., the surface energy and work of adhesion, Wa, were consistent with macro-mechanical properties. Fromthe T-peel test combined with electrical resistance (ER), the Ru catalyst coated CF fabric/ENB composite respondedreasonably well with high peeling strength. The different Ru catalyst processing methods resulted in different interfacial,mechanical, and electrical sensing properties, with the Ru catalyst coated CF composites typically having better properties. This study is about the Ru catalyst coated CF fabric, which can be applied to manufacture geometrically complex and largestructural composites and will help improve product manufacturing efficiency and quality.
백영민,신평수,김종현,박하승,K. Lawrence DeVries,박종만 한국섬유공학회 2019 Fibers and polymers Vol.20 No.11
Currently, continuous polymer fibers are usually manufactured in versatile forms such as, aramid fiber. In thisstudy, continuous polycarbonate (PC) fiber having the uniform diameter was manufactured from a thermoplastic PC resinusing a twin screw extruder. Carbon nanotubes (CNTs) were uniformly dispersed in the PC resin, using a solvent dispersionmethod. The effect of CNT on the mechanical properties of PC fiber was analyzed statistically, using Weibull distribution, bysingle PC fiber tensile test. Dynamic contact angle was measured to compare the surface energies of PC fiber and PC-CNTfiber on the water droplet. The difference in the wetting patterns was also observed by injecting a solvent between two fibers. Tensile strength and Young’s modulus of the PC fiber was significantly increased by the addition of even a small amount ofCNT. This improvement can be attributed to the excellent reinforcing and stress transferring effects of the CNT filler. Composites were made of both types of PC film and PC fiber as a matrix and their impregnation properties were investigatedby inspection of photographs of their cross-sections. The mechanical properties of the two-types of composites were alsocompared by tensile testing. From the cross-sectional fractography and the permeated PC weight, PC fiber type exhibitedbetter impregnation property than the PC film type, and thus resulted in the improved tensile strength.
김종현,권동준,박종만,K. Lawrence DeVries 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11
Adhesion of hybrid composite materials is essential in the manufacture of wind turbine blades. In the case of huge composite structures, however, the adhesive section between hybrid composite (GFRP, CFRP) was too thick, and it could be lead to decrease adhesion peroperty. In this research, adhesive properties were investigated with different adhesive thicknesses for glass fiber and carbon fiber reinforced hybrid composites. As the adhesive thickness increased, the lap shear strength (LSS) decreased in a rather exponential function. In addition, there were problems that as the thickness of the adhesive increases, voids easily formed inside the adhesive, and the thick adhesive layer had low resistance to bending. Even when the thick bonding section was formed with GFRP addition, added GFRP was deformed more in the bonding part upon the applied external stress. This could be because the interfacial stress was greater than that of the neat epoxy adhesive. It was monitored by 3D electrical resistance (ER) mapping of the CFRP substrate was used to evaluate the shear stress transfer of the bonding part and the CFRP substrate. The addition of GFRP to the epoxy adhesive can improve the adhesion and the resistance to shear failure for thick adhesive parts, such as wind turbine blades (WTB).
백영민,신평수,김종현,박하승,권동준,K. Lawrence DeVries,박종만 한국섬유공학회 2018 Fibers and polymers Vol.19 No.8
The mechanical and interfacial properties were evaluated for carbon fiber reinforced composites (CFRC) manufactured using thermally recycled waste carbon fiber and recycled polyethylene terephthalate (PET). The mechanical properties of the recycled fiber were determined and compared to those of neat fibers using the single-fiber tensile test. The surfaces of the recycled and neat carbon fiber were examined and compared using FE-SEM and dynamic contact angle measurements. A goal of the study was to determine the applicability of industrial use of recycled CF and/or recycled PET in CFRC. Mechanical properties were measured using short beam and tensile tests. These properties were observed to be correlated with crystallinity. The interfacial properties between the recycled carbon fibers and recycled PET were evaluated using the microdroplet test. At low temperature residual resin remained on the recycled CFs surface resulting relatively the low interfacial properties. At excessively high temperatures, oxidation occurred, on the CFs surface, which also resulting in relatively poor low mechanical properties. The optimal treatment condition was 500 oC, where the surface was relatively clean and the reduction in mechanical properties was minimized.
Down the Rabbit Hole-Considerations for Ingested Foreign Bodies
Jerry Brown,Molly Kidder,Abigail Fabbrini,Jonathan deVries,Jason Robertson,Nicole Chandler,Michael Wilsey 대한소아소화기영양학회 2019 Pediatric gastroenterology, hepatology & nutrition Vol.22 No.6
We report the case of a seven-year-old boy with an ingested foreign body, which was retained within the appendix for a known duration of ten months, ultimately requiring appendectomy. The ingested foreign body was incidentally discovered by abdominal x-ray at an emergency room visit for constipation. Despite four bowel cleanouts, subsequent x-rays showed persistence of the foreign body in the right lower quadrant. While the patient did not have signs or symptoms of acute appendicitis, laparoscopic appendectomy was performed due to the risk of this foreign body causing appendicitis in the future. A small metallic object was found within the appendix upon removal. This case highlights the unique challenge presented by foreign body ingestions in non-verbal or developmentally challenged children and the importance of further diagnostic workup when concerns arise for potential retained foreign bodies.
Kwon, D.J.,Wang, Z.J.,Choi, J.Y.,Shin, P.S.,DeVries, K.L.,Park, J.M. Elsevier Science Ltd 2016 Composites Applied science and manufacturing Vol.82 No.-
Dispersion of the nano-fillers is important in the manufacture of high performance nanocomposites. Dispersion of silane treated CNT/epoxy composites was analyzed for various alkyl chain lengths. Difference in mobility of alkyl chains of different length affects the excluded free volume and repulsive forces. An optimal chain length was observed to impart maximum mechanical and impact properties. Differences in the dispersion of CNT due to alterations in alkyl chain lengths were determined using electrical resistance measurement. Spreading of CNT/epoxy rearranged the CF tow resulting in a change in electrical resistance ratio (CERR) and the differences in alkyl chain length effected CNT spreading. Dispersion and wetting conditions with different alkyl chain lengths resulted in changes in CERR, ILSS and other proprieties. The butyl chain length was optimal of the alkyl chain lengths studied. This is attributed to the butyl chains known good mobility and steric repulsion effects compared to longer alkyl chain lengths.
신평수,Jong-Hyun Kim,Ha-Seung Park,백영민,이상일,K. Lawrence DeVries,박종만 한국섬유공학회 2020 Fibers and polymers Vol.21 No.2
Composites has been an area of active research for the past several decades due to their lightweight and good mechanical properties. However, the aging of fiber reinforced composites is a major issue due to exposure of thermal, waterand ultraviolet conditions. Continuous damage could bring about mechanical property degradation and damage at the interface. This is a comprehensive review on of aging effects in water, heat, ultraviolet etc. on composites and the changes in chemical, mechanical and interfacial properties, evaluated by nondestructive and micro-mechanic evaluations. It focuses particularly on composites with superior chemical, mechanical and interfacial properties, as well as good high resistance to aging, as these are considered to be important Structural materials. Types of composites and aging effects of aged composite by exposure to water, heat and ultraviolet radiation are explored. Based on these nondestructive and micro-mechanical evaluations methods are suggested to reduce the diverse ageing effects.