• Title, Summary, Keyword: dendrite structure

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The cellular basis of dendrite pathology in neurodegenerative diseases

  • Kweon, Jung Hyun;Kim, Sunhong;Lee, Sung Bae
    • BMB Reports
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    • v.50 no.1
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    • pp.5-11
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    • 2017
  • One of the characteristics of the neurons that distinguishes them from other cells is their complex and polarized structure consisting of dendrites, cell body, and axon. The complexity and diversity of dendrites are particularly well recognized, and accumulating evidences suggest that the alterations in the dendrite structure are associated with many neurodegenerative diseases. Given the importance of the proper dendritic structures for neuronal functions, the dendrite pathology appears to have crucial contribution to the pathogenesis of neurodegenerative diseases. Nonetheless, the cellular and molecular basis of dendritic changes in the neurodegenerative diseases remains largely elusive. Previous studies in normal condition have revealed that several cellular components, such as local cytoskeletal structures and organelles located locally in dendrites, play crucial roles in dendrite growth. By reviewing what has been unveiled to date regarding dendrite growth in terms of these local cellular components, we aim to provide an insight to categorize the potential cellular basis that can be applied to the dendrite pathology manifested in many neurodegenerative diseases.

A Study on the Growing Characteristics of Dendrite Structure of Melted Wire Deteriorated by Over Current (과전류 열화에 의해 용단된 전선의 수지상 조직 성장특성에 관한 연구)

  • Shong, Kil-Mok;Choi, Chung-Seog;Kim, Dong-Woo;Kwak, Hee-Ro
    • Proceedings of the KIEE Conference
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    • pp.1463-1465
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    • 2003
  • In this paper, we studied on the growing characteristics of dendrite structure of melted wire deteriorated by over current. Electric wire was melted by Jolue's heat. By using HSIS(High Speed Imaging System), we found out a lot of melted parts of wire were dispersed and radiated. Electric wire had narrow melted areas in case of short fusing time. A lot of very small dots generated around the grain of copper cross-section and they were changed into dendrite structure. Dendrite structure appeared at the values lower than 2.5[A/sec]. In case of very short fusing time, fusing current was calculated by empirical formula. The Preece equation was not enough to analyze a variety of characteristics of melted wire because it did not consider melting time, atmosphere, etc.

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The Heating Characteristics of Electric Bare Wire Melted by AC Current (AC 전류에 의해 용융된 나전선의 발열 특성)

  • Shong, Kil-Mok;Choi, Chung-Seog;Kim, Hyong-Kon;Kim, Young-Seok
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.1
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    • pp.77-84
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    • 2006
  • For a fire cause judgement this paper describes the heating characteristics of electric bare wire melted by AC current. The cower wires prepared for the experiment were 1.2[mm], 1.6[mm], and 2.0[mm] in diameter. Through the cross section analysis(CSA), it was confirmed that the dendrite structure grew at the angle of about 40[$^{\circ}$] or 60[$^{\circ}$] when the fusing current was applied to the wires. The larger the fusing current is, the more decreased the growth angle of the dendrite structure is. It was confirmed that the dendrite structure was arranged like the columnar structure.

The Cross Section Analysis CSA based on the Short Circuit Conditions of the Low Voltage Bare Wires (저압용 나전선의 단락조건에 의한 단면 분석)

  • Shong, Kil-Mok;Kim, Dong-Ook;Kim, Dong-Woo;Kim, Young-Seok;Choi, Chung-Seog
    • Proceedings of the KIEE Conference
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    • pp.2094-2096
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    • 2005
  • In this paper, we studied the cross section analysis based on the short circuit conditions of the low voltage bare wires. The copper wires prepared for the experiment were 1.2mm 1.6mm and 2.0mm in diameter. Through the cross section analysis(CSA), it was confirmed that the dendrite structure grew at the angle of about $40^{\circ}$ or $60^{\circ}$ when the fusing current was applied to the wires. The larger the fusing current is, the more decreased the growth angle of the dendrite structure is. It was confirmed that the dendrite structure was arranged like the columnar structure. In this paper, the characteristics analysis of short circuit was carried out in the range of transient duration.

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A Study on the Characteristics Analysis of Strands Melted by Over Current (과전류에 의해 용단된 소선의 특성해석에 관한 연구)

  • Choi, Chung-Seog;Kim, Hyang-Kon;Kim, Dong-Ook
    • Journal of the Korean Society of Safety
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    • v.19 no.1
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    • pp.60-65
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    • 2004
  • The PVC insulated flexible cords are used mainly as power supply cords of electric appliance. This electric wire is a stranded wire consisted of dozens of strands. In case stranded wires are disconnected by mechanical stress, it weakens electrically. Finally, the over current flows through stranded wires, and electrical fire occurs. In this study, we analyzed the melting properties of strands by over current, such as melting process, melting current and melting time. And we analyzed that quantity of heat for melting, a cross sectional structure, and surface structure by optical microscope and SEM. As analysis results, melting time decreased as melting current increased. And quantity of heat for melting was low, too. From the cross sectional structure of melted wire, when a melting current low and melting time long, it was found that the dendrite structure grew. However, the dendrite structure is hard to grow because growing time is not enough when a melting current high and melting time short.

Flow Stress and Deformation Behavior of Zr-based Bulk Metallic Glass Composite in Supercooled Liquid Region (Zr계 비정질 복상 합금의 과냉 액상 영역에서의 유동 음력과 변형거동)

  • Jun, H.J.;Lee, K.S.;Chang, Y.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.417-420
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    • 2006
  • The composition and structure of dendrite phase within $Zr_{76.11}Ti_{4.20}Cu_{4.51}Ni_{3.16}Be_{1.49}Nb_{10.53}$ bulk metallic glass (BMG) were confirmed by using an EPMA, XRD and TEM, respectively. The chief elements of dendrite phase were Zr-Ti-Nb and had a BCC structure. The thermal properties of this BMG have been then subsequently investigated by using a differential scanning calorimeter (DSC). The glass transition and crystallization onset temperatures were determined as $339.7^{\circ}C$ and $375.8^{\circ}C$ for this alloy, respectively. Mechanical properties have also been examined by conducting a series of uniaxial compression tests at various temperatures within supercooled liquid region under the strain rates between $10^{-4}/s$ and $3{\times}10^{-2}/s$. The deformation behavior of BMG composite within supercooled liquid region is similar to one of Vit-1 exhibiting amorphous single phase alloy. The flow stresses of BMG composite, however, are entirely higher than those of Vit-1 because dendrite phases are interfere with moving of atoms.

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Mechanism of Twin Columnar Growth in Aluminum Alloys (알루미늄 합금의 TCG 조직의 형성기구)

  • Kim, D.K.;Sanders Jr., T.H.
    • Journal of Korea Foundry Society
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    • v.7 no.3
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    • pp.192-198
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    • 1987
  • Commercial semicontinuous cast ingots of aluminum alloys often exhibit large grains composed of parallel arrays of continuous lamellae. Each lamella consists of a central {111} coherent twin boundary and wavy solidification boundary. This microstructure is referred to as a twin columnar growth(TCG) structure. The factors influencing the formation of a TCG structure include a unidirectional thermal gradient and the critical range of the alloying element content. The higher the thermal gradient is, the shorter the twin plane spacings are. The composition profile for an untwinned dendrite shows maximums at the positions of the interdendritic channels and the minimum appears at the center of the dendrite. While for twinned dendrite, it has wavy apperance. This profile has two local minimums instead of one shown in the untwinned.

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A Study on the Characteristics of Short Circuit through the Cross Section Analysis of Electric Wire (전선의 단면분석을 통한 단락특성에 관한 연구)

  • Shong, Kil-Mok;Choi, Chung-Seog;Kim, Yun-Hoi;Kim, Sang-Hyeon;Park, Nam-Kyu
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.51-56
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    • 2005
  • For a fire cause judgement this paper describes the short circuit characteristics of a electric wire through the cross section analysis under ac condition. The cower wires prepared for the experiment were 1.2mm, 1.6mm, and 2.0mm in diameter. Through the cross section analysis(CSA), it was confirmed that the dendrite structure grew at the angle of about $40^{\circ}\;or\;60^{\circ}$ when the fusing current was applied to the wires. The larger the fusing current is, the more decreased the growth angle of the dendrite structure is. It was confirmed that the dendrite structure was arranged like the columnar structure. In this paper, the characteristics analysis of short circuit was carried out in the range of transient duration and the correlation constant k was investigated by measuring the short circuit duration and the fusing current.

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Characteristics of electrodeposited bismuth telluride thin films with different crystal growth by adjusting electrolyte temperature and concentration

  • Yamaguchi, Masaki;Yamamuro, Hiroki;Takashiri, Masayuki
    • Current Applied Physics
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    • v.18 no.12
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    • pp.1513-1522
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    • 2018
  • Bismuth telluride ($Bi_2Te_3$) thin films were prepared with various electrolyte temperatures ($10^{\circ}C-70^{\circ}C$) and concentrations [$Bi(NO_3)_3$ and $TeO_2:1.25-5.0mM$] in this study. The surface morphologies differed significantly between the experiments in which these two electrodeposition conditions were separately adjusted even though the applied current density was in the same range in both cases. At higher electrolyte temperatures, a dendrite crystal structure appeared on the film surface. However, the surface morphology did not change significantly as the electrolyte concentration increased. The dendrite crystal structure formation in the former case may have been caused by the diffusion lengths of the ions increasing with increasing electrolyte temperature. In such a state, the reactive points primarily occur at the tops of spiked areas, leading to dendrite crystal structure formation. In addition, the in-plane thermoelectric properties of $Bi_2Te_3$ thin films were measured at approximately 300 K. The power factor decreased drastically as the electrolyte temperature increased because of the decrease in electrical conductivity due to the dendrite crystal structure. However, the power factor did not strongly depend on the electrolyte concentration. The highest power factor [$1.08{\mu}W/(cm{\cdot}K^2$)] was obtained at 3.75 mM. Therefore, to produce electrodeposited $Bi_2Te_3$ films with improved thermoelectric performances and relatively high deposition rates, the electrolyte temperature should be relatively low ($30^{\circ}C$) and the electrolyte concentration should be set at 3.75 mM.

Evolution on Microstructure and Mechanical Property of Ti65Fe35 Hypereutectic Alloys by Adding Low Melting Temperature Elements (저융점 원소의 첨가에 따른 Ti65Fe35 과공정 합금의 미세구조와 기계적 특성의 변화)

  • Hwang, Yun Jung;Hong, Sung Hwan;Kim, Jeong Tae;Kim, Young Seok;Park, Hae Jin;Kim, Hee Jin;Jeong, Yeon Beom;Lee, Young Hoon;Kim, Ki Buem
    • Korean Journal of Materials Research
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    • v.27 no.10
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    • pp.557-562
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    • 2017
  • The microstructural evolution and modulation of mechanical properties were investigated for a $Ti_{65}Fe_{35}$ hypereutectic alloy by addition of $Bi_{53}In_{47}$ eutectic alloys. The microstructure of these alloys changed with the additional BiIn elements from a typical dendrite-eutectic composite to a bimodal eutectic structure with primary dendrite phases. In particular, the primary dendrite phase changed from a TiFe intermetallic compound into a ${\beta}$-Ti solid solution despite their higher Fe content. Compressive tests at room temperature demonstrated that the yield strength slightly decreased but the plasticity evidently increased with an increasing Bi-In content, which led to the formation of a bimodal eutectic structure (${\beta}$-Ti/TiFe + ${\beta}$-Ti/BiIn containing phase). Furthermore, the (Ti65Fe35)95(Bi53In47)5 alloy exhibited optimized mechanical properties with high strength (1319MPa) and reasonable plasticity (14.2 %). The results of this study indicate that the transition of the eutectic structure, the type of primary phases and the supersaturation in the ${\beta}$-Ti phase are crucial factors for controlling the mechanical properties of the ultrafine dendrite-eutectic composites.