Computational simulation on steric hindrance between hydrophobic tails of lamellar matrix composed of acyl glutamate/stearyl alcohol/behenyl alcohol by molecular dynamics

Seo, D.S.,Kim, J.C.,Kim, D.P. Korean Society of Industrial and Engineering Chemi 2008 Journal of industrial and engineering chemistry Vol.14 No.6

Monosodium N-stearoyl-l-glutamate (MSSG), an amino acid surfactant, could associate with higher alcohols such as stearyl alcohol (SA) and behenyl alcohol (BA) and they were self-assembled into a lamella in an aqueous phase. When MSSG, SA and BA were assumed to associate each other in molar ratios of 1:1:1, 1:2:1, 1:1:2, 1:2:2 and 1:1:3, the packing parameter of each associate was calculated using molecular dynamics (MD). Among them, only 1:1:1 associate and 1:1:3 one exhibited packing parameters of around 1. According to the result of colloidal stability, however, the lamella composed of 1:1:3 associate was poorly stable while that of 1:1:1 associate was stable. In order to explain why the colloidal stability is not related to the packing parameter, the concept of steric compressibility was introduced. Steric compressibility is a measure of vertical steric hindrance occurred between hydrophobic tails of lamella. The value of steric compressibility, calculated by MD, of 1:1:1 and 1:1:3 associates were 4.7 and 8.2, respectively. That is, the vertical repulsion in the lamella of 1:1:3 associate might be greater than in the lamella of 1:1:1 associate. This would account for why the lamella of 1:1:3 associate is poorly stable even though the packing parameter is almost 1. Besides the condition that packing parameter is to be around 1, the steric compressibility of lamella should be as low as possible to achieve a stable lamella.

Computational simulation on steric hindrance between hydrophobic tails of lamellar matrix composed of acyl glutamate/stearyl alcohol/behenyl alcohol by molecular dynamics

Dong-Sung Seo,Dong-Pyo Kim,김진철 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.6

Monosodium N-stearoyl-L-glutamate (MSSG), an amino acid surfactant, could associate with higher alcohols such as stearyl alcohol (SA) and behenyl alcohol (BA) and they were self-assembled into a lamella in an aqueous phase. When MSSG, SA and BAwere assumed to associate each other in molar ratios of 1:1:1, 1:2:1, 1:1:2, 1:2:2 and 1:1:3, the packing parameter of each associate was calculated using molecular dynamics (MD). Among them, only 1:1:1 associate and 1:1:3 one exhibited packing parameters of around 1. According to the result of colloidal stability, however, the lamella composed of 1:1:3 associate was poorly stable while that of 1:1:1 associate was stable. In order to explain why the colloidal stability is not related to the packing parameter, the concept of steric compressibility was introduced. Steric compressibility is a measure of vertical steric hindrance occurred between hydrophobic tails of lamella. The value of steric compressibility, calculated by MD, of 1:1:1 and 1:1:3 associates were 4.7 and 8.2, respectively. That is, the vertical repulsion in the lamella of 1:1:3 associate might be greater than in the lamella of 1:1:1 associate. This would account for why the lamella of 1:1:3 associate is poorly stable even though the packing parameter is almost 1. Besides the condition that packing parameter is to be around 1, the steric compressibility of lamella should be as low as possible to achieve a stable lamella.

판상형 Glass-flake를 이용한 내캐비테이션 도료 개발 및 성능평가

박혜영 ( Hyeyoung Park ),김성길 ( Sung-gil Kim ),김상석 ( Sang-suk Kim ),최이찬 ( I-chan Choi ),김병우 ( Byungwoo Kim ),김승진 ( Seung-jin Kim ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.2

유체의 흐름에 의한 부분적 진공현상인 캐비테이션이 재료 표면에 충격을 주어 철강류 표면이 마모되는 현상에 대응하기 위해 판상형 glass-flake를 적용한 내캐비테이션용 도료를 개발하였다. 특히, 가소성이 좋고 내수성이 뛰어난 특성의 NBR (Acrylonitrile-butadiene rubber) 변성 에폭시 수지에 판상형 glass-flake를 필러로 상용하여 유·무기 복합 세라믹 코팅도료를 개발하였다. 특히 glass-flake는 두께는 100~200 nm 정도로 박막형이며, 길이는 20~30 μm 정도의 판상으로 종횡비가 약 200~300배에 달해 마모 및 내식성에 우수한 성능을 나타낸다. 본 도료로 도막형성 후 접착강도, 인장강도, 연신률, 내캐비테이션 성능을 평가한 결과, 인장강도 4.8~6N/㎟ 이상, 파단연신률 30%이상, 마식속도 10 ㎟/h이하, 복합사이클 내식성시험에서 모두 우수한 성능을 보였다. 특히 내 캐비테이션 성능 평가에서 기존 선진외국 제품대비 2배 이상의 우수한 성능을 나타내었다. In response to the cavitation caused by the partial vacuum caused by the fluid flow, a paint was developed by dispersing the lamella-shaped glass-flake in resin for anti-cavitation. This composite paint was developed by using the inorganic filler (lamella shaped glass-flake) and the NBR (Acrylonitrile-butadiene rubber) which was modified epoxy resin. Especially, the glass-flake was a thin film with a thickness of about 100~200 nm and length of about 20~30 μm, the aspect ratio was about 200 to 300 times that of the plate-shaped. So the paint for anti-cavitation have shown excellent performance in corrosion resistance. The results of evaluating anti-cavitation performance was below, tensile strength 4.8~6 N/mm2 or more, rupture elongation 30% or higher, abrasive speed 10 mm2/h or less. In particular, it showed more than twice the superior performance compared to existing advanced foreign products in anti-cavitation performance evaluation.

폴리에틸렌과 파라핀 混合物의 球晶 모포로지

金圭範,金東建 진주산업대학교 2001 산업과학기술연구소보 Vol.- No.8

폴리에틸렌과 파라핀의 混合比가 다른 film 試料와 더불어 파라핀만을 有機溶液으로 溶解 除去한 試料의 表面觀察 및 폴리에틸렌 球晶間의 構造를 檢討한 結果는 다음과 같다. 폴리에틸렌의 比率을 어느 정도까지는 적게 하는 것에 따라서 球晶間의 衝突이 적게 되어 球晶成長이 增加하였다. 그러나, 보다 적게 하면 파라핀의 比率이 增加해 이번에는 파라핀 分子가 球晶으로서 形成하는 lamella의 伸長 및 回傳을 沮害하여 球晶이 成長하지 못하는 것을 알 수 있었다. 또한, 球晶間 構造의 觀察에 있어서는 파라핀이 除去된 폴리에틸렌의 honeycomb構造를 가진 球晶의 側面으로부터 fibril이 다리와 같은 形態로 球晶間이 連結되어져 있는 것을 알 수 있었다. This study was analysed and discussed to identify the structure of spherulites in the mixtures of Polyethylene film and Paraffin, which was blended in the ratio control and Paraffin was solvolysised. In the investigation of spherulitic morphologies, SEM and polarizing microscopy was used. An effect was occured in spherulites grown to some extent when the ratios of Polyethylene are in the small and little collisions between spherulites, whereas it was observed that the growth can also not occur as the increase of Paraffin and the hinderance in extending and turning lamellae. It was shown by revealing that the spherulites are connected with fibrils like a bridge between them from the side views of Polyethylene spherulitic morphologies when Paraffin are cleared out and presented the honeycomb form.

A study of plastic plateau disappearance in stress-strain curve of annealed polypropylene films during stretching

Lei, Caihong,Wu, Shuqiu,Xu, Ruijie,Xu, Yunqi,Peng, Xinlong Techno-Press 2013 Advances in materials research Vol.2 No.2

The changes of plastic plateau in the stress-strain curves of annealed polypropylene (PP) films during stretching under room temperature were followed and the corresponding melting properties and microstructure were characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). It was found that during stretching the plastic plateau disappeared progressively with the increase of drawing ratio. At the same time, the endotherm plateau in DSC curves also disappeared progressively. The presence of the plastic plateau was attributed to the stretching of unstable crystalline part which was formed by tie chains around initial row-nucleated lamellae structure during annealing. During stretching, the unstable part was stretched and converted to bridges connecting separated lamellae. There was direct relationship between the disappearance of plastic plateau and pore formation.

Anatomy, ultrastructure and histology of the olfactory organ of the largemouth bass Micropterus salmoides, Centrarchidae

박종영,김현태,윤성운 한국현미경학회 2019 Applied microscopy Vol.49 No.6

The detailed anatomy, ultrastructure and histology of the olfactory organ of Micropterus salmoides were investigated by a stereo microscope, a light microscope, and a scanning electron microscope. Its external structure shows a tube-like anterior nostril to stick out and a posterior nostril flat to the skin surface. Meanwhile, its internal structure, the olfactory chamber, contains a fan-shaped rosette structure with 9 to 11 lamellae in adult fish over 35 cm in standard length (SL) and two accessory nasal sacs (ethmoidal and lacrimal sacs) were found. Interestingly, the rosette in young fish under 15 cm in SL was a longitudinal structure in parallel with each of 4–5 lamellae. Histologically, the sensory epithelium (SE) on the olfactory chamber consists of 5 types of cells: olfactory receptor neurons, supporting cells, basal cells, lymphatic cells and mucous cells. In contrast, the non-sensory epithelium (NSE) has stratified epithelial cells, lymphatic cells and mucous cells. The mucous cells of the SE are abundant and distributed densely in one row on the outermost superficial surface, but the one of the NSE are less than the SE. From these results, the olfactory characters of M. salmoides may be related with its ecological habit spending in the middle layer of stagnant water contaminated, more or less.

[P076] A case of porokeratosis ptychotropica

( Je Byeong Chae ),( Jung Won Shin ) 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.1

A 47-year-old man presented with a 1-year history of verrucous plaques affecting buttocks. Histological examination revealed psoriasiform hyperplasia with cornoid lamellae. He was treated with 40% salicylic acid ointment and methylprednisolone cream. However, they had no beneficial effects and the patient was lost to follow-up. Four months later, he revisited and the lesion had become more extensive and verrucous. In addition, many satellite lesions had developed around the buttocks and in both forearms. The second skin biopsy was done and the results were similar with those of the previous one. Considering clinical and histopathologic findings together, a diagnosis of porokeratosis ptychotropica (PP) was made. We have tried various treatment including cryotherapy, triamcinolone injection, CO₂ laser, and dermabrasion. However, they had only limited effect. He is now under observation after changing the treatment with oral isotretinoin. PP is a rare variant of porokeratosis and it usually presents as symmetrical distribution on erythematous scaly papules on buttocks. Careful examination in necessary, since PP might be difficult to differentiate clinically from PRP, psoriasis, and ILVEN. To our knowledge, approximately 30 cases had been reported in the literatures. Herein, we report a case of recalcitrant PP with extensive satellite lesions.

A Study on Potential Histological Effectiveness of German chamomile oil in Atopic Dermatitis

이순희(Soon Hee Lee),김영철(Young Chul Kim),이재순(Jae Soon Lee) 한국인체미용예술학회 2011 한국인체미용예술학회지 Vol.12 No.1

생후 7주령된 웅성 BALB/c 마우스의 배부를 전기제모기로 제모하고 2,4-dinitrochloro-benzene(DNCB)으로 아토피성 피부염을 유발시킨 후 아토피성 피부염에 대한 German chamomile oil(GC oil, Matricaria chamomile)의 효과를 조직학적으로 관찰하기 위해 동물실험을 수행하였다. 대조군은 saline을, 오일도포군은 호호바 오일에 희석한 3% 저먼 카모마일 오일을 1일 1회, 주 6회, 매 회 70㎕씩 4주 동안 도포하였다. 실험결과 광학현미경적 관찰에서 오일 도포 4주에 오일도포군은 대조군에 비해 표피 각질층 내 lipid 양이 많고 lipid lamella가 선상으로 고르게 배열되었고, 진피와 피하층 내 mast cell의 분포와 탈과립 정도가 적었으며, 진피내 호중구와 림프구수의 감소와 함께 염증정도가 완화됨으로써 저먼 카모마일 오일은 만성적인 아토피성 피부염의 치료 및 예방에 효과가 있는 것으로 판단된다.

Lyotropic Behaviors of a Phospholipid-based Lamella Liquid Crystalline Phase Hydrated by Propylene Glycol as a Polar Solvent: Correlation of DSPC vs PG Concentration

Jeong, Tae-Hwa,Oh, Seong-Geun Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.1

The lyotropic behaviors to form the structure of distearoylphosphatidylcholine (DSPC)-based liquid crystal (LC) hydrated by only propylene glycol (PG) without water were examined by differential scanning calorimetry (DSC), X-ray diffractions (XRD), polarized microscope (PM) and transmission electron microscope (TEM). By increasing the amount of PG instead of water, it showed the phase transition to be gradually changed from anisotropic structures to other structures more close to isotropic ones and their appearance to be changed from solid-like states to liquid-like ones with more fluidity. Below 50% w/w PG, the mixtures of DSPC and PG resulted in no direct observation of LC structure through PM because they were very close to solid-states. From 55% w/w to 90% w/w of PG, the dense lamella crystalline structures were observed through PM, and their thickness and area decreased as the content of PG increased. Measured by DSC with heating process, the main phase transition from α -lamella phase to isotropic phase appeared from 52.89 °C to 47.41 °C to show linearly decreasing behaviors because PG affects the hydrophobic region of DSPC-based lamella phase. The repeating distance of the lamella phase and the interlayer distance between bilayers were calculated with XRDs and the average number of bilayers related to the thickness in LC structure was approximately estimated by combining with TEM results. The WAXS and DSC measurements showed that all of PG molecules contributed to swelling both the lipid layer in the edge region of lamella phase close to phosphate groups and the interlayer between bilayers below 90% w/w of PG. The phase and thermal behaviors were found to depend on the amount of PG used by means of dissolving DSPC as a phospholipid and rearranging its structure. Instead of water, the inducement of PG as a polar solvent in solid-lamella phase is discussed in terms of the swelling effect of PG for DSPC-based lamella membrane.

The Middle Lamella Remainders on the Surface of Various Mechanical Pulp Fibres

KECHENG LI,XUEQUAN TAN,DONGBO YAN 한국펄프·종이공학회 2006 한국펄프종이학회 기타 간행물 Vol.- No.-

The surface of various mechanical pulp fibres including thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), and alkaline peroxide mechanical pulp (APMP) fibres, were characterized using SEM, AFM, and XPS. With SEM and AFM, middle lamella material was observed to be non-fibrillar, patch-like, while fibre secondary wall was observed to have a microfibrillar structure. It was found that after the first-stage refiner, lignin-rich middle lamella remainders are present on the fibre surface of all three pulps, although most of the fibre surfaces expose microfibrillar structure. After the final-stage refining, large amounts of granules are present on the TMP fibre surface. In contrast, most middle lamella remainders remain on the surface of CTMP fibres after final stage refining and even after peroxide bleaching. XPS results have confirmed that the non-fibrillar surface material is the lignin-rich middle lamella remainder., and the remainders of middle lamella contribute to the high surface lignin concentration.