• 한국해양공학회지
• /
• 제31권3호
• /
• pp.241-247
• /
• 2017

Plywood, which is created by bonding an odd number of thin veneers perpendicular to the grain orientation of an adjacent layer, was developed to supplement the weak points such as contraction and expansion of conventional wood materials. With structural merits such as strength, durability, and good absorption against impact loads, plywood has been adopted as a structural material in the insulation system of a membrane type liquefied natural gas (LNG) carrier. In the present study, as an attempt to resolve recent failure problems with plywood in an LNG insulation system, conventional PF (phenolic-formaldehyde) resin plywood and its alternative MUF (melamine-urea-formaldehyde) resin bonded plywood were investigated by performing material bending tests at ambient ($20^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures to understand the resin and grain effects on the mechanical behavior of the plywood. In addition, the failure characteristics of the plywood were investigated with regard to the grain orientation and testing temperature.

• 대한소아치과학회지
• /
• 제5권1호
• /
• pp.33-38
• /
• 1978

It has been studied that aminoacetonitrile was associated with the inhibition of collagen fiber, argyrophilic fiber and oxytalan fiber synthesis. This experiment was performed, by the basic knowledge of above mentioned study, to study on the biological effect of aminoacetonitrile to the developing periodontal ligament in Sprague Dawley rat. twenty two of female rats weighing about 200gm were gestated. In 7 days after gestation, the experimental rats were injected aminoacetonitrile 7 times intraperitoneally. After parturition, delivered fJtuses were divided into 4 groups and each group was sacrificed to 1 day, 7 days, 14 days, and 21 days after delivery, schematically. All the fetuses were observed on their periodontal ligament by histological and histo chemical methods. To study on the components of periodontal ligament fiber in these experimental study van Gieson, Masson's trichrom, argyrophilic fiber, oxytalan fiber, methyl green pyronin and periodic acid-Shiff staining were performed. Results were as follows; 1) Retardation of functional orientation in periodontal ligament collagen fiber was observed in 1 day fetuses hut this appearance was diminished gradually and recovered in normal condition in 7 days fetuses. 2) Distribution of argyrophilic fiber in 1 day fetuses was oriented delicately and loosely but volume of this fiber was gradually thickened and distributed densely. 3) Oxytalan fiber was oriented dendritic ally and contradictorily in 14 days fetuses but their orientation was changed into oblique form in middle portion of roof and their numbers were increased gradually. 4) Pyronin-philic stain of fibroblast was gradually deepened in 7 days fetuses and this finding also suggested to the depreciation of collagen synthesis in this specimen. 5) PAS positive line was observed continuousely at the portion of cervical to the middle root surface.

• 한국정보전자통신기술학회논문지
• /
• 제17권3호
• /
• pp.155-165
• /
• 2024

환원된 산화 그래핀(rGO)을 알루미늄, 티타늄, 스트론튬이 혼합된 졸-겔 용액에 혼합하여 브러시 코팅법을 이용하여 액정배향용 하이브리드 박막을 제조하였다. 160, 260, 및 360℃에서 어닐링한 후 산화 반응의 차이를 관찰하였다. 박막 제조 과정에서 생성된 졸-겔 용액은 브러시 모의 전단 응력에 의해 수축력을 발생시켜 미세홈 구조를 형성하였다. 이러한 구조는 주사 전자 현미경 분석을 통해 확인되었으며, rGO의 존재가 명확하게 보였다. 어닐링 온도가 증가함에 따라서 박막 표면의 산화 및 환원 반응이 더욱 활성화되어 표면 혼합물의 강도가 증가하였다. 또한 혼합물의 강도를 증가시킴으로써 전기광학적 특성이 안정화되고 개선되었다. 더불어 전압-정전용량 값도 크게 향상되었다. 최종적으로 투과율 측정 결과 액정디스플레이의 액정 배향막으로 적용하기에 적합한 것으로 나타났다.

• Journal of Microbiology and Biotechnology
• /
• 제30권5호
• /
• pp.633-641
• /
• 2020

Microbial rhodopsins are a superfamily of photoactive membrane proteins with the covalently bound retinal cofactor. Isomerization of the retinal chromophore upon absorption of a photon triggers conformational changes of the protein to function as ion pumps or sensors. After the discovery of proteorhodopsin in an uncultivated γ-proteobacterium, light-activated proton pumps have been widely detected among marine bacteria and, together with chlorophyll-based photosynthesis, are considered as an important axis responsible for primary production in the biosphere. Rhodopsins and related proteins show a high level of phylogenetic diversity; we focus on a specific class of bacterial rhodopsins containing the '3 omega motif.' This motif forms a stack of three non-consecutive aromatic amino acids that correlates with the B-C loop orientation and is shared among the phylogenetically close ion pumps such as the NDQ motif-containing sodium-pumping rhodopsin, the NTQ motif-containing chloride-pumping rhodopsin, and some proton-pumping rhodopsins including xanthorhodopsin. Here, we reviewed the recent research progress on these 'omega rhodopsins,' and speculated on their evolutionary origin of functional diversity.

• 한국동물학회지
• /
• 제27권2호
• /
• pp.93-102
• /
• 1984

Xenopus laevis의 수정란의 한천층을 cysteine용액으로 용해시킨후 다시 예리한 forceps으로 vitelline membrane을 제거하였다. 막을 제거한 수정란을 제1분열이 일어나기 직전 미래의 복측 (vental side)부분을 중력에 대하여 반대방향인 위쪽으로 향하게 하거나 또는 중력에 마주 대하도록 아랫쪽으로 배열하였다. 그후 tailbud 시기까지 발생시켜 2중체축 (double axis) 형성률을 조사하였다. 그 결과 수정란을 동물 반구가 위로 향하는 자연상태와 다르도록 배열하는 것은 2중체축 형성에 큰 요인으로 작용하지 못하였고 오히려 수정란의 외형을 유지시키는 물리적 구조(편평형 또는 구형)가 더 큰 요인임이 밝혀졌다. 이와같은 관찰은 무미양서류 수정란의 극성 결정 메카니즘과 배의 제1차 유도작용을 연구하는데 좋은 자료를 제고하여 준다.

• 센서학회지
• /
• 제19권3호
• /
• pp.209-213
• /
• 2010

This paper describes the fabrication and characteristics of AlN piezoelectric MPG(micro power generator). The micro energy harvester was fabricated to convert ambient vibration energy to electrical power as a AlN piezoelectric cantilever with Si proof-mass. To be compatible with CMOS process, AlN thin film was grown at low temperature by RF magnetron sputtering and micro power generators were fabricated by MEMS technologies. X-ray diffraction pattern proved that the grown AlN film had highly(002) orientation with low value of FWHM(full width at the half maximum, $\theta=0.276^{\circ}$) in the rocking curve around(002) reflections. The implemented harvester showed the $198.5\;{\mu}m$ highest membrane displacement and generated 6.4 nW of electrical power to $80\;k{\Omega}$ resistive load with $22.6\;mV_{rms}$ voltage from 1.0 G acceleration at its resonant frequency of 389 Hz. From these results, the AlN piezoelectric MPG will be possible to suitable with the batch process and confirm the possibility for power supply in portable, mobile and wearable microsystems.

• Bulletin of the Korean Chemical Society
• /
• 제20권5호
• /
• pp.581-586
• /
• 1999

A series of polyethers containing the thiazole or oxazole subcyclic moiety have been synthesized. Reaction of 2-aryl-4-hydroxymethylthiazole with tetra- and pentaethylene glycol di-p-tosylate in THF provided corresponding α,ω-bis[2'-aryl-4'-methylthiazole]polyethylene glycol in good yields. Similar treatment of 2-phenyl-4-hydroxymethyloxazole 7 and 2-phenyl-5-hydroxymethyloxazole 8 with tetraethylene glycol di-p-tosylate yielded the corresponding 1,13-bis [2'-phenyl-4'-methyloxazole]tetraethylene glycol 16 and 1,13-bis[2'-phenyl-5'-methyloxazole]tetraethylene glycol 17 in 69 and 43% yields in respectively. The potentiometric properties of PVC-based ion selective membranes containing 66 wt% o-nitrophenyloctyl ether (NPOE) and 4 wt% polyethers 9-17 have been examined. The membranes containing thiazole and oxazole polyether derivatives exhibited high selectivity toward silver (I) ion. It was observed that the response slopes of the electrodes to silver ion vary with the length of polyether chain linking two thiazole subcyclic moiety. Potentiometric data suggest that the number of ether units, CH2OCH2, for phenylthiazole derivatives be greater than 5 to result in near-Nernstian response. However, the response behaviors of the membrane electrodes based on phenyloxazole podands 16 and 17, which have different orientation, were correspondingly similar to those of the electrodes based on phenylthiazole podands 9 and 10. On the other hand, the ISEs based on thiazole polyether derivatives with different terminal substituents, e.g., phenyl 10, naphtyl 14, and thienyl 15, except that with pyridyl 12, exhibited little difference in their potentiometric properties.

• Membrane and Water Treatment
• /
• 제10권3호
• /
• pp.245-250
• /
• 2019

Prussian blue (PB) is well known for its excellent $Cs^+$ ions adsorption capacity. Due to the high dispersibility of PB in aqueous phase, composite materials imbedding PB in supporting materials have been introduced as a solution. However, building PB particles inside porous supporting materials is still difficult, as PB particles are not fully formed and elute out to water. In this study, we suggest layer-by-layer (LBL) assembly to provide better immobilization of PB on supporting materials of poly vinyl alcohol sponge (PVA) and cellulose filter (CF). Three different PB attachment methods, ex-situ/in-situ/LBL assembly, were evaluated using PB leaching test as well as $Cs^+$ adsorption test. Changes of surface functionality and morphology during PB composite preparation protocols were monitored through Fourier transform infrared spectroscopy and scanning electron microscopy. The results indicate that LBL assembly led to better PB attachment on supporting materials, bringing less eluting PB particles in aqueous phase compared to other synthesis methodologies, such as ex-situ and in-situ synthesis. By enhancing the stability of the adsorbent, adsorption capacity of PVA-PB with LBL improved nine times and that of CF-PB improved over 20 times. Therefore, the results suggest that LBL assembly offers a better orientation for growing PB particles on porous supporting materials.

• The Plant Pathology Journal
• /
• 제39권5호
• /
• pp.417-429
• /
• 2023

Ralstonia solanacearum species complex (RSSC) is a soil borne plant pathogen causing bacterial wilt on various important crops, including Solanaceae plants. The bacterial pathogens within the RSSC produce exopolysaccharide (EPS), a highly complicated nitrogencontaining heteropolymeric polysaccharide, as a major virulence factor. However, the biosynthetic pathway of the EPS in the RSSC has not been fully characterized. To identify genes in EPS production beyond the EPS biosynthetic gene operon, we selected the EPS-defective mutants of R. pseudosolanacearum strain SL341 from Tn5-inserted mutant pool. Among several EPSdefective mutants, we identified a mutant, SL341P4, with a Tn5-insertion in a gene encoding a putative NDP-sugar epimerase, a putative membrane protein with sugar-modifying moiety, in a reverse orientation to EPS biosynthesis gene cluster. This protein showed similar to other NDP-sugar epimerases involved in EPS biosynthesis in many phytopathogens. Mutation of the NDP-sugar epimerase gene reduced EPS production and biofilm formation in R. pseudosolanacearum. Additionally, the SL341P4 mutant exhibited reduced disease severity and incidence of bacterial wilt in tomato plants compared to the wild-type SL341 without alteration of bacterial multiplication. These results indicate that the NDP-sugar epimerase gene is required for EPS production and bacterial virulence in R. pseudosolanacearum.

• Journal of Plant Biology
• /
• 제38권1호
• /
• pp.87-93
• /
• 1995

최근에 Synechocystis sp. PCC 6803 중에 한 균주가 고체 한천 배지상에서 일정한 조명(300-1000 lux) 방향을 따라 활주 운동하는 것을 관찰하여 이 종을 S. 6803 PTX라고 명명하고 이의 주광성 운동에 대한 생리학적 특징을 이해하기 위하여 몇 가지 대사 억제제와 신호 전달 차단제의 주광성 운동에 미치는 효과를 조사하였다. DCMU는 광계 II로부터 광계 I의 일차 전자 수용체인 플라스토퀴논으로의 비순환성 광합성 전자전달을 억제하는 억제자로서 $100\;\mu\textrm{M}$의 농도에서는 주광성 운동을 억제하지 못하였다. 그러나 호흡에 의한 전자전달 억제제인 sodium azide를 처리하였을 경우에는 S. 6803 PTX에서 심하게 장해를 받았다. 이러한 관찰 결과는 주광성 운동의 주동력원이 광인산화 과정보다는 호흡에 의한 산화적인 인산화과정에 주로 연관되어 있음을 보여주었다. 또한, 세포를 CCCP나 DNP와 같은 막상의 uncoupler를 처리하였을 때, 세포내 ATP 농도를 저하시키거나 세포질막에 수소 이온의 전기화학구배($\Delta\mu_{H}+$)를 제거시키나, 이러한 화합물들은 주광성 운동에 뚜렷한 영향은 주지 못하였다. 이러한 결과와는 달리, H+-F0F1 ATPase에 민감하게 억제 작용을 나타내는 DCCD나 NBD의 처리는 세포내 ATP만 고갈시키고 막상에서 $\Delta\mu_{H}+$는 그대로 유지시키는 작용을 하는데, 이러한 DCCD나 NBD는 주광성 운동에 대해서는 심하게 억제 현상을 나타내었다. 또한, 특이성 calcium ionophore 중의 하나인 A23187의 처리는 양성 주광성에 심하게 장해를 주었다. 아마도 Ca2+ 유동은 주광운동 방향성의 신호전달 과정에 중요하게 관련되어 있는 것으로 나타났다. 마지막으로 S-adenosyl methionine과 같은 메틸 공여체의 고갈이 S. 6803 PTX 균주의 주광성 반응에 영향을 주는지를 알아보기 위하여 에티오닌을 BG11을 한천 배지에 첨가하였다. 이 생물종의 광운동은 에티오닌의 농도가 증가됨에 따라 일정하게 억제되다가 0.5mM에서 주광성 운동을 완전히 억제시켰다. 이것은 광수용 기작이 Escherichia coil나 Salmonella typhimurium에서 발견된 메틸기 수용 주화성 단백질과 같은 메틸화/탈메틸화 과정에 의하여 조절될 가능성을 보여주고 있음을 의미한다.