For automotive parts used at elevated temperatures, such as transmission cases and engine blocks, it is necessary to improve the creep resistance of magnesium alloys. For this reason, various ...magnesium alloys have been developed for elevated temperature applications. In this study, the microstructure and creep behavior of CaO added Mg-Al-Si alloys (Mg-5.0Al-0.7Si, Mg-5.0Al-0.7Si-0.5CaO, Mg-5.0Al-0.7Si- 0.5CaO-0.3Sr) were investigated. The microstructures were observed by OM, SEM and TEM. To evaluate the mechanical properties, tensile tests were carried out at room and high temperature, and creep tests were performed at 150 ℃ with applied loads from 50 to 80 MPa.
신경독성 조개류 중독 3례 고영길; Young Gil Ko; 안지영 ...
대한임상독성학회지,
12/2006, Letnik:
4, Številka:
2
Journal Article
Recenzirano
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Neurotoxic shellfish poisoning (NSP) can result from eating filter-feeding shellfish carrying brevetoxins produced by the marine dinoflagellate Krenia brevis (formally Gymnodinium breve). Brevetoxins ...enhance sodium entry into cells via voltage-sensitive sodium channels and have an excitatory effect. The incubation period is three hours (range 15 minutes-18 hours). NSP is characterized by gastroenteritis combined with neurologic symptoms. Gastrointestinal (GI) symptoms include abdominal pain, nausea, diarrhea and burning pain in the rectum. Neurologic symptoms are paresthesia, reversal of hot and cold temperature sensation, myalgia, headache, vertigo, and ataxia. Other symptoms may include malaise, tremor, dysphagia, bradycardia, decreased reflexes, dilated pupils, seizure, and coma. The health problem caused by K. breviscan be associated with a red tide bloom. We encountered 3 cases of neurotoxic shellfish poisoning. They all presented with GI and neurologic symptoms andrecovered after conservative treatment.
High-resolution (chirp, 2–7 kHz) reflection profiles from the southern continental slope and basin plain of the Ulleung Basin reveal three echo types. Sediment texture and geotechnical properties ...were analyzed using 22 piston cores. Echo type 1 shows a sharp bottom echo with discrete, continuous subbottom reflectors with a flat or undulatory upper surface interpreted as turbidite/hemipelagic sediment. It is dominant in the basin plain. Echo type 2 is characterized by laterally wedged, an acoustically transparent masses (debrites). This type occurs in the southern lower slope and base-of-slope area. Echo type 3 shows irregular blocky/lumpy or hyperbolic masses with various amount of internal deformation, (interpreted as slide/slump deposits). It occurs in the middle to upper slope area. These echo types show a zonal distribution.Sediment texture in the basin plain, especially mean grain size appears to be the most important parameter for the variations in geotechnical properties (wet bulk density, porosity, velocity, and shear strength). The variations in geotechnical properties with burial depth in the southern slope are dependent strongly on sediment compaction and/or consolidation. Overall, geotechnical properties and sediment texture change significantly from the southern slope area to the basin floor, suggesting that sediments were probably originated from the southern margin. The slope sediments especially are relatively compacted due to the mass flow processes. Therefore, the geotechnical properties of the plain and slope sediments show significantly different values.
The distribution of the nerve growth factor (NGF), the glial fibrillary acidic protein (GFAP) and the ciliary neurotrohic factor (CNTF) was performed in coronal sections of the mesencephalon, ...rhombencephalon and spinal cord in the developing Mongolian gerbils. Generally, NGF specifically recognizes neurons with the NGF receptor, whereas GFAP does the glia, and CNTF does the motor neurons. The receptor expression was examined separately in gerbils between embryonic days 15 (E15) and postnatal weeks 3 (PNW 3). The NGF-IR was first observed in the spinal cord at E21, which might be related to the maturation. The GFAP reactivity was peaked at the postnatal days 2 (PND2), while the highest CNTF-reaction was expressed at PNW 2. The GFAP stains were observed in the aqueduct and the spinal cord, which appeared to project laterally at E19. The CNTF was observed only after the birth and found in both the neurons and neuroglia of the substantia nigra, mesencephalon, cerebellum and the spinal cord from PND1 to PNW3. These results suggest that NGF, GFAP and CNTF are important for the development of the neurons and the neuroglia in the central nervous system at the late prenatal and postnatal stages.
In this work, the effects of the dispersive condition and surface energy change of multi-walled carbon nanotube (MWCNT) on the mechanical properties of amino-function-alized MWCNT containing carbon ...fibers-reinforced epoxy composites were studied. Amino-functionalization of MWCNT was carried out by grafting spermidine and p-phenyl-enediamine onto the surfaces of MWCNT through amidation. The surface properties of the MWCNT before and after amidation were observed using scanning electron microscope (SEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscope (XPS), micro-scope, and contact angle measurements. Theoretical interfacial adhesions between the MWCNT and the epoxy resins were studied by calculating the work of adhesion and demonstrated by interlaminar shear strength (ILSS). From the experimental results, it was found that amino-functionalized MWCNT showed quite a homogeneous dispersion state in epoxy matrix resins. Additionally, the interfacial adhesions could be improved by amino-functionalizing MWCNTs surfaces. Consequently, the introduction of an amino-functional group on MWCNT surfaces positively affected the dispersibility of MWCNT, which resulted in improving the mechanical properties of the carbon fibers-reinforced epoxy composites.
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