• The Plant Pathology Journal
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• 제27권1호
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• pp.8-13
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• 2011

The induced resistance of cucumber leaves treated with oligochitosan to the infection of the cucumber powdery mildew, Sphaerotheca fuliginea, was investigated using transmission electron microscopy. The results showed that when the plants were treated with oligochitosan and challenged with inoculum, a significant decrease of the disease occurred. The mycelial development in the treated leaves was markedly inhibited. The cytoplasm of the powdery mildew mycelium was aggregated, with its organelles disintegrated and the cytoplasm collapsed. The protoplasm in haustoria became electron-dense. Haustoria became malformed, their organelles disintegrated, the hausterial wall thickened and eventually the whole complex necrotized. The host cells produced defence structures and materials associated with infection and a hypersensitive response. The host cell wall was thickened and deeply stained; several layers of papilla structure were produced under the cell wall; dark materials were deposited between the cell wall and plasmalemma; extrahaustorial plasmalemma was deeply stained and extrahaustorial matrix appositions had large deposits of electron-dense material; the cytoplasm was disordered, host organelles disintegrated and eventually the whole host cell disintegrated and necrotized.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.159-169
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• 2019

The activated carbon materials were prepared from waste biomass by ultrasonic assisted chemical activation method (UCA), ultrasonic assisted physical activation method (UPA) and Manganese nitrogen doped carbon (Mn/N-C). The XRD result shows the turbostatic (fully disordered) structure. The cyclic voltammetry test was done at 50 mV/s using 1M sodium sulfate and the values of specific capacitance were found to be 93, 100 and 115 F/g for UCA, UPA and Mn/N-C respectively. The power density values for the samples UCA, UPA and Mn/N-C were found to be 46.04, 87.97 and 131.42 W/kg respectively. The electrochemical impedance spectroscopy was done at low frequency between 1 to 10 kHz. The Nyquist plot gives the resistant characteristics of the materials due to diffusional resistance at the electrode-electrolyte interface. The Energy Dispersive X-Ray Spectroscopyanalysis (EDAX) analysis showed that the percentage doping of nitrogen and manganese were 3.53 wt% and 9.44 wt% respectively. It is observed from the experiment Mn/N-C doped carbon show good physical and electrochemical properties.

• Bulletin of the Korean Chemical Society
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• 제6권6호
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• pp.344-347
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• 1985

Perovskite type oxides of $SrTiO_3,SrZrO_3,and\;SrTi_{1-x}Zr_xO_3$ have been systematically synthesized at $1250^{\circ}C$and $1550^{\circ}C$ with specimens containing additions of up to x=0.9 of zirconium by solid state reactions and characterized by X-ray diffraction. X-ray diffraction studies showed that the compound $SrTi_{1-x}Zr_xO_3$ has cubic structure. The lattice paramters of $SrTi_{1-x}Zr_xO_3$ solid solutions obey the Vegard's law and fairly large increase in volume can acompany the formation of this solution with increasing Zr content(X). Assuming the lattice constants of perovskite type compounds $A(B_{1-x}B'_x)O_3$where $B_{1-x}B'_x$ is $Ti_{1-x}Zr_x$, to be a linear function of the ionic radii of B and B' ions, the disordered ion pair of $Ti^{4+}$and $Zr^{4+}$ was verified from the lattice constants of a series compounds varying x=0,0.05, 0.25, 0.5, 0.75, 0.9, and 1.0 with known isovalent pairs.

• BMB Reports
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• 제57권6호
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• pp.263-272
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• 2024

Amyloid-β (Aβ) is one of the amyloidogenic intrinsically disordered proteins (IDPs) that self-assemble to protein aggregates, incurring cell malfunction and cytotoxicity. While Aβ has been known to regulate multiple physiological functions, such as enhancing synaptic functions, aiding in the recovery of the blood-brain barrier/brain injury, and exhibiting tumor suppression/antimicrobial activities, the hydrophobicity of the primary structure promotes pathological aggregations that are closely associated with the onset of Alzheimer's disease (AD). Aβ proteins consist of multiple isoforms with 37-43 amino acid residues that are produced by the cleavage of amyloid-β precursor protein (APP). The hydrolytic products of APP are secreted to the extracellular regions of neuronal cells. Aβ 1-42 (Aβ42) and Aβ 1-40 (Aβ40) are dominant isoforms whose significance in AD pathogenesis has been highlighted in numerous studies to understand the molecular mechanism and develop AD diagnosis and therapeutic strategies. In this review, we focus on the differences between Aβ42 and Aβ40 in the molecular mechanism of amyloid aggregations mediated by the two additional residues (Ile41 and Ala42) of Aβ42. The current comprehension of Aβ42 and Aβ40 in AD progression is outlined, together with the structural features of Aβ42/Aβ40 amyloid fibrils, and the aggregation mechanisms of Aβ42/Aβ40. Furthermore, the impact of the heterogeneous distribution of Aβ isoforms during amyloid aggregations is discussed in the system mimicking the coexistence of Aβ42 and Aβ40 in human cerebrospinal fluid (CSF) and plasma.

• 한국해양환경ㆍ에너지학회지
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• 제20권1호
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• pp.18-25
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• 2017

기후변화의 영향으로 자연재해에 의한 인명 및 재산의 피해가 증가함에 따라 자연재해 취약성에 관한 연구들이 근래에 폭넓게 수행되고 있으며, 기후변화의 영향평가와 적응 방재대책 마련이 활발히 진행되고 있다. 종래의 재해영향을 평가한 연구에서는 대리변수를 이용하여 취약성 평가를 수행하였으나, 이는 정성적이고 상대적인 결과를 도출하여 절대적인 비교나 방재 또는 적응능력의 기준을 제시하기 어려운 경향이 있다. 따라서 본 연구에서는 시스템 생태학적 접근법으로 재해를 Order와 Disorder의 관계로 인식하고 에머지평가법을 이용하여 정량적인 평가를 하고자 하였다. 먼저, 2003년 부산시를 대상으로 유입 에너지와 내부 자산을 파악하였고, 태풍 매미로 인해 발생 된 태풍 에너지, 태풍 영향 그리고 복구 에너지를 분석하였다. 그 결과, 유입 에너지는 4.66E+22 sej/yr, 내부 자산은 1.98E+22 sej, 태풍 에너지는 7.80E+18 sej, 태풍 영향은 4.55E+20 sej, 복구 에너지는 3.87E+20 sej로 나타났다. 이를 통해 재해 에너지에 대한 재해 영향을 허리케인 앤드류와 비교 고찰해봤을 때, 부산시의 방재능력을 증가시킬 경우, 매미보다 큰 태풍의 에너지에 대한 영향 정도를 줄일 수 있음을 알 수 있었고 피해에 대한 실질적인 복구를 통하여 추가피해에 대한 예방이 필요함을 알 수 있었다. 따라서 본 연구는 재해에 대한 영향을 동일한 척도로 나타내어 자연환경과 인간의 경제 시스템별로 정량적이게 파악할 수 있었으며 이러한 정량적인 취약성 평가가 이루어지고 추후 태풍 크기에 따라 방재능력을 어느 정도까지 증가시키는 것이 효율적인 방재인지에 대한 추가적인 연구를 통해 도시의 방재정책마련에 기여할 수 있을 것으로 판단된다.

• Journal of Photoscience
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• 제9권2호
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• pp.66-69
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• 2002

Zinc chlorin 1 possessing tertiary 3$^1$_hydroxy and 13$^1$-oxo groups was synthesized as a model for the antenna chlorophylls of photosynthetic green bacteria. Self-aggregation of 1 in nonpolar organic solvents was examined and compared to 2 and 3 possessing a secondary and primary 3$^1$_hydroxy group, respectively. Zinc chlorin 1 self-aggregated in I％(v/v) CH$_2$Cl$_2$-hexane to form oligomers and showed a red-shifted Qy maximum at 704 nm compared to the monomer (648 nm in CH$_2$CI2$_2$). This red-shift is larger than that of 3$^1$S-2 (648 to 697 nm) and comparable to that of3$^1$R-2 (648 to 705 nm), but smaller than that of 1 (648 to 740 nm), indicating that while a single 3$^1$-methyl group (primary to secondary OH) suppressed tight and/or extended aggregation, the additional 3$^1$-methyl group (secondary to tertiary OH) did not further suppress aggregation. The relative stability of the aggregates was in the order 3> 3$^1$R-2∼ 1 > 3$^1$S-2 as determined by visible spectral analyses. Molecular modeling calculations on oligomers of zinc chlorins 1, 3$^1$ R-2 and 3 gave similar well-ordered energy-minimized structures, while 3 stacked more tightly than 3$^1$ R- 2 and 1. In contrast, 3$^1$S-2 gave a relatively disordered (twisted) structure. The calculated oligomeric structures could explain the visible spectral data of 1-3 in nonpolar organic solvents. Moreover, self- aggregation of synthetic zinc 13$^1$_oxo-hlorins 4-6 possessing a 2-hydroxyethyl, 3-hydroxypropyl and 3- hydroxy-I-propenyl group at the 3-position in nonpolar organic solvents was discussed.

• 한국잠사곤충학회지
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• 제37권1호
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• pp.33-38
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• 1995

견 fibroin을 8M LiBr 수용액에 침지하여 연신처리에 의한 견의 구조와 물성변화를 시험해 보았다. 1. 연사의 역학적 성질은 8M LiBr 수용액의 처리온도 상승에 따라서 강도와 신도는 증가하나 Young's율은 감소하는 경향이었다. 8$0^{\circ}C$ 처리의 X선회절에 있어서는 염축에 의해 분자배향은 흐트러지나 SilkII형의 결정구조는 변하지 않았다. 2. 8M LiBr수용액을 사용하여 8$0^{\circ}C$에서 1시간 처리하면 160%정도 연신이 가능하며 고연신시의 역학적 성질에 있어서는 강도와 Young's율은 증가하고 신도는 감소하였으나 X선회절에서는 연신율의 증가와 함께 결정이 고배향화되는 경향이었다. 3. DSC의 시차열 Thermogram에서 무처리의 연사와 8M LiBr 수용액에 처리되어진 미연신의 연사사이에는 열분해거동이 다른 것이 관찰되었으며 열분해 최대 Peak점의 온도는 연신율의 증가에 따라 조금씩 고온쪽으로 이동함으로써 X선회절사진의 결과와 일치하고 있다.

• Journal of Electrochemical Science and Technology
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• 제2권1호
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• pp.1-7
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• 2011

Nanocomposites of reduced graphene oxide and manganese (II,III) oxide can be synthesized by the freeze-drying process of the mixed colloidal suspension of graphene oxide and manganese oxide, and the subsequent heat-treatment. The calcined reduced graphene oxide-manganese (II,III) oxide nanocomposites are X-ray amorphous, suggesting the formation of homogeneous and disordered mixture without any phase separation. The reduction of graphene oxide to reduced graphene oxide upon the heat-treatment is evidenced by Fourier-transformed infrared spectroscopy. Field emission-scanning electronic microscopy and energy dispersive spectrometry clearly demonstrate the formation of porous structure by the house-of-cards type stacking of reduced graphene oxide nanosheets and the homogeneous distribution of manganese ions in the nanocomposites. According to Mn K-edge X-ray absorption spectroscopy, manganese ions in the calcined nanocomposites are stabilized in octahedral symmetry with mixed Mn oxidation state of Mn(II)/Mn(III). The present reduced graphene oxide-manganese oxide nanocomposites show characteristic pseudocapacitance behavior superior to the pristine manganese oxide, suggesting their applicability as electrode material for supercapacitors.

• Journal of Photoscience
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• 제9권2호
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• pp.122-125
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• 2002

Coherent oscillations in is fluorescence dynamics of W.-t. PYP and its site-directed mutants have been observed. Two oscillatory modes coupled with the ultrafast fluorescence due to the twisting of the excited chromophore were identified, a high ftequency mode (∼135 cm$\^$-1/) with ∼550 is damping time and a low frequency overdamped mode (-45 cm$\^$-1/) with ∼250 is damping time, respectively. Both modes disappear in the fluorescence dynamics of denatured PYP emphasizing the important role of the protein nanospace as the environment for photoreaction. The qualitative picture of fluorescence dynamics in site-directed mutants was rather similar to that in W.-t. PYP, i.e., similar oscillatory modes (∼130-140 cm$\^$-1/ and ∼40-70 cm$\^$-1/) have been observed. This indicates that the vibrational modes and electron-vibration couplings do not change dramatically due to the mutation though the damping time of low frequency mode a little decreases as the protein nanospace structure becomes looser and more disordered by mutation. On the other hand, in the case of some PYP analogues, the qualitative picture of fluorescence dynamics changes, showing the familiar picture of solvation effect whereas the oscillations are almost damped. Comparative analyses of these observations are presented.

• 대한기관식도과학회지
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• 제2권1호
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• pp.71-81
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• 1996

1992년 1월부터 1994년 12월까지 전남대학병원에서 경부 전산화단층촬영을 시행한 환자 중 경부에 종양, 염증성 질환 등 기질적인 질환 및 경부외상의 기왕력이 없는 45례의 경부 전산화단층촬영상에서 캘리퍼스 및 분도기를 이용하여 후두의 좌우 대칭성, 설골 및 성문의 위치, 후두의 길이 및 좌우 갑상 연골이 이루는 각도 등을 계측하여 다음과 같은 결과를 얻었다. 1. 대부분의 경우에서 후두구조는 어느 정도 비대칭성을 보였고 우측편위가 좌측편위보다 많았으며 성별 및 연령별에 따라 의의있는 차이는 없었다. 2. 설골의 높이는 제 2-3경추 부위에서 제 5-6경추 부위까지 위치하고 있었고 제 3-4경추 부위 가 가장 흔한 부위였다. 3. 성문의 높이는 제 4경추 부위에서 제 6-7경추간까지 위치하고 있었고 제 5경추 부위가 가장 흔한 부위였다. 4. 양측 갑상연골이 이루는 각도는 58도에서 100도까지 다양하였고 평균 81.5도였으며, 평균각도는 남성에서 77.24도, 여성에서 87.88도였다.