Preliminary Study of a New Extracorporeal Membrane Oxygenator Development When Using Pulsatile Flow

Lee, Sa-Ram,Lee, Kyung-Soo,Jung, Jae-Hoon,Mun, Cho-Hay,Min, Byoug-Goo The Korean Society of Medical and Biological Engin 2007 의공학회지 Vol.28 No.3

An oxygenator is a very important artificial organ and widely used for patients with lung failure or during open heart surgery. Although an oxygenator has been widely studied worldwide to enhance its efficiency, studies on oxygenators, in particular when using a pulsatile blood flow, are domestically limited. Therefore, a new oxygenator was developed in the lab and animal experimental results are described in the paper. The oxygenator is composed of polycarbonate housing and polypropylene hollow fibers. It has a total length of 400 mm and a surface area of $1.7 m^2$. The animal experiment lasted for 4 hours. The blood flow rate was set to 2 L/min and a pulsatile blood pump, T-PLS (Twin-Pulse Life Support), was used. Samples were drawn at the oxygenator's inlet and outlet. The total hemoglobin (Hb), saturation oxygen ($sO_2$), and partial oxygen pressure ($pO_2$), partial $CO_2$ pressure ($pCO_2$), and plasma bicarbonate ion concentration ($HCO_3^-$) were measured. The oxygen and carbon dioxide transfer rates were also calculated based on the experimental data in order to estimate the oxygenator's gas transfer efficiency. The oxygen and carbon dioxide transfer rates were $16.4{\pm}1.58$ and $165.7{\pm}10.96 mL/min$, respectively. The results showed a higher carbon dioxide transfer rate was achieved with the oxygenator. Also, the mean inlet and outlet blood pressures were 162.79 and 137.92 mmHg, respectively. The oxygenator has a low pressure drop between its inlet and outlet. The aim of own preliminary study was to make a new oxygenator and review its performance when applying a pulsatile blood pump thus, confirming the possibility of a new oxygenator suitable for pulsatile flow.

Guest-Guest Interactions and Co-Occupation by Distinct Guests in the Metastable State of Clathrate Hydrates

Lee, Bo Ram,Sa, Jeong-Hoon,Hong, Sang Yeon,Lee, Ju Dong,Lee, Kun-Hong,Seo, Yongwon,Sum, Amadeu K. American Chemical Society 2019 The Journal of Physical Chemistry Part C Vol.123 No.6

<P>The current knowledge of guest-guest interactions and co-occupation in clathrate hydrates is exclusive for the same guests (H<SUB>2</SUB> or N<SUB>2</SUB>) at moderate pressure. Here, we introduce the unusual co-occupation of distinct guests in the metastable state of hydrates. With controlled hydrate fraction, particle size, and intensification of the sintering of SF<SUB>6</SUB> hydrate particles formed from water and SF<SUB>6</SUB> gas as a help gas, we observed an abnormal but unique synchronous behavior in Raman intensities of two guest molecules (SF<SUB>6</SUB> and N<SUB>2</SUB>/H<SUB>2</SUB>) in hydrates consistently and repeatedly; over time, the scattering intensity for the guests (i) increases, (ii) decreases, and (iii) finally reaches the stable level. Without a concentration change of SF<SUB>6</SUB>, this abnormal behavior must arise from the possible changes in the scattering cross section of the molecules, suggesting that N<SUB>2</SUB>/H<SUB>2</SUB> strongly interacts with SF<SUB>6</SUB> in the large cages, resulting in a possible co-occupation during the metastable transition. These observations on the metastability of gas hydrate attest the importance of the sintering effect as a barrier to prevent fast gas diffusion for reaching equilibrium, which could have significant implication in increasing overall gas storage in clathrate hydrates.</P> [FIG OMISSION]</BR>

QCM(Quartz Crystal Microbalance)을 이용한 가스 하이드레이트 상평형 측정 방법

이보람(Lee, Bo Ram),사정훈(Sa, Jeong-Hoon),박다혜(Park, Da-Hye),이건홍(Lee, Kun-Hong) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

가스 하이드레이트는 물분자와 저분자량의 가스분자가 고압과 저온에서 수소결합을 이루며 형성되는 결정성 화합물을 말한다. 최근 가스 하이드레이트의 물리적 특성과 형성 원리를 이용하여 다양한 분야로의 적용 연구가 수행되고 있는데 이의 효과적 달성을 위해서는 가스 하이드레이트의 상평형 연구가 필수적이다. 기존에 수행되는 상평형 실험 방법은 온도의 변화에 따라 하이드레이트를 해리시키고 압력의 변곡점을 찾는 것으로 최소 24시간이 소요되지만, 본 연구진이 제안하는 QCM을 이용한 방법은 1 ng의 무게에 1 Hz의 변화를 나타내는 수정진동자의 민감성을 이용한 것으로 약 2~3시간 내에 상평형 실험을 수행할 수 있고, 하이드레이트의 기억효과(Memory Effect)를 이용하여 연속적인 상평형 실험도 가능하다. 본 연구에서는 QCM 반응기의 원리 및 실험 방법에 대하여 설명하고 열역학적 촉진제를 첨가한 상평형 실험결과를 제시함으로써 상대적으로 저렴한 가격으로 다양한 촉진제와 억제제 첨가 시 나타나는 상평형 효과를 빠른 시간 내에 선별할 수 있는 방법으로 QCM을 이용한 방법을 제안하고자 한다.

Thermodynamic promoter effects on the phase equilibrium of BFG(Blast Furnace Gas) hydrate

이보람(Lee, Bo Ram),사정훈(Sa, Jeong-Hoon),박다혜(Park, Da-Hye),곽계훈(Kwak, Kye-Hoon),이건홍(Lee, Kun-Hong) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11

CO₂ separation from a flue gas by using the gas hydrate technology was suggested by Kang et al. They reported phase equilibrium conditions of mixed gases composed of CO₂ and N2 with THF as a thermodynamic promoter. In this study, we reported the phase equilibrium conditions of a mixed gas which had a realistic composition of the blast furnace gas (BFG) emitted from the steel-making process. The phase equilibrium measurements were done by using the continuous QCM method, and the results demonstrate that this method is efficient and as accurate as the conventional temperature search method.

Diffusion-Enhanced Modified Hemodialyzer

Lee, Kyung-Soo,Lee, Sa-Ram,Mun, Cho-Hae,Min, Byoung-Goo The Korean Society of Medical and Biological Engin 2007 의공학회지 Vol.28 No.4

Flow mismatch between blood and dialysate is invariably encountered during conventional hemodialysis, and this deteriorates diffusive mass transfer. A modification of a conventional dialyzer was conceived to prevent this mismatch. The modified dialyzer includes two independent blood flow regions (central and peripheral regions), which were achieved by redesigning the dialyzer cap. Resultantly, the blood stream was divided into two concentric dialyzer regions. Solutes clearances obtained using the modified dialyzers were compared with those of conventional dialyzers. Solutes clearances by conventional dialyzers were uniform, but solutes clearances by modified dialyzers were found to be dependent on the simulated blood split into dialyzer central and peripheral regions. Maximal clearances using the modified dialyzer were improved by up to approximately 7.6% for urea and 7.3% for creatinine, as compared with those of conventional dialyzers. More optimizations are required for clinical applications, but the finding that blood flowrates through central and peripheral fiber bundles can be easily regulated is encouraging.

Amino Acids as Natural Inhibitors for Hydrate Formation in CO₂ Sequestration

Sa, Jeong-Hoon,Lee, Bo Ram,Park, Da-Hye,Han, Kunwoo,Chun, Hee Dong,Lee, Kun-Hong American Chemical Society 2011 Environmental science & technology Vol.45 No.13

<P>The motivation for this work was the potential of hydrophobic amino acids such as glycine, <SMALL>l</SMALL>-alanine, and <SMALL>l</SMALL>-valine to be applied as thermodynamic hydrate inhibitors (THIs). To confirm their capabilities in inhibiting the formation of gas hydrates, three-phase (liquid–hydrate–vapor) equilibrium conditions for carbon dioxide hydrate formation in the presence of 0.1–3.0 mol % amino acid solutions were determined in the range of 273.05–281.45 K and 14.1–35.2 bar. From quantitative analyses, the inhibiting effects of the amino acids (on a mole concentration basis) decreased in the following order: <SMALL>l</SMALL>-valine > <SMALL>l</SMALL>-alanine > glycine. The application of amino acids as THIs has several potential advantages over conventional methods. First, the environmentally friendly nature of amino acids as compared to conventional inhibitors means that damage to ecological systems and the environment could be minimized. Second, the loss of amino acids in recovery process would be considerably reduced because amino acids are nonvolatile. Third, amino acids have great potential as a model system in which to investigate the inhibition mechanism on the molecular level, since the structure and chemical properties of amino acids are well understood.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2011/esthag.2011.45.issue-13/es200552c/production/images/medium/es-2011-00552c_0010.gif'></P>

Pulse Push/Pull Hemodialysis: In Vitro Study on New Dialysis Modality With Higher Convective Efficiency

Lee, Kyungsoo,Lee, Sa Ram,Mun, Cho Hae,Min, Byoung Goo Blackwell Publishing Inc 2008 Artificial Organs Vol.32 No.5

<P>Abstract: </P><P>Midsize molecule retention is related with renal-failure-associated mortality. Here, the authors describe a new dialysis modality, pulse push/pull hemodialysis (PPPHD), which increases convective clearance. Blood and dialysate are circulated by a pulsatile pump, but with pulsatile flow patterns that are 180° out of phase. This causes blood-to-dialysate pressure gradients that oscillate between positive and negative, and which cause consecutive periods of ultrafiltration and backfiltration. The devised PPPHD was compared with conventional high-flux hemodialysis (CHFHD) in terms of solute clearances, albumin loss, and total protein levels. Human plasma containing dissolved uremic marker molecules was used as a blood substitute, and clearances were investigated for blood urea nitrogen, creatinine, vitamin B12, and inulin. Observed clearances were found to be significantly higher for PPPHD by approximately 3–14% for low-molecular-weight solutes, by 47–48% for vitamin B12, and by 38–49% for inulin than for CHFHD. No albumin loss was observed in either of these two study groups. The authors conclude that PPPHD offers a simple straightforward means of enhancing uremic molecule removal by increasing total ultrafiltration volume without the need to infuse replacement fluid.</P>

Abnormal incorporation of amino acids into the gas hydrate crystal lattice

Sa, Jeong-Hoon,Kwak, Gye-Hoon,Lee, Bo Ram,Ahn, Docheon,Lee, Kun-Hong The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.48

<P>Gas hydrates are crystalline ice-like solid materials enclosing gas molecules inside. The possibility of the presence of gas hydrates with amino acids in the universe is of interest when revealing the potential existence of life as they are evidence of a source of water and organic precursors, respectively. However, little is known about how they can naturally coexist, and their crystallization behavior would become far more complex as both crystallize with formation of hydrogen bonds. Here, we report abnormal incorporation of amino acids into the gas hydrate crystal lattice that is contrary to the generally accepted crystallization mode, and this resulted in lattice distortion and expansion. The present findings imply the potential for their natural coexistence by sharing the crystal lattice, and will be helpful for understanding the role of additives in the gas hydrate crystallization.</P> <P>Graphic Abstract</P><P>Gas hydrates are crystalline ice-like solid materials enclosing gas molecules inside. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp05056h'> </P>

친환경적인 열역학적 저해제를 첨가한 CO₂ 하이드레이트 상평형 측정

사정훈(Sa, Jeong-Hoon),이보람(Lee, Bo Ram),박다혜(Park, Da-Hye),이건홍(Lee, Kun-Hong) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

가스 하이드레이트는 낮은 온도와 높은 압력 조건에서 물 분자들이 수소 결합을 통해 형성하는 3차원의 격자구조에 저분자량의 기체 분자들이 포획되어 있는 결정성 화합물이다. 가스 하이드레이트는 형성 시 많은 양의 가스를 저장할 수 있는 특성을 가진다. 천연 가스를 심해저로 수송하는 수송관 내부에 가스 하이드레이트가 생성되면 막힘 현상이 일어나 비용과 시간 측면에서 막대한 손실이 일어날 수 있다. 따라서 이를 방지하기 위해 열역학적 상평형 조건을 변화시켜 가스 하이드레이트 형성을 방지할 수 있는 열역학적 저해제에 관한 연구의 필요성이 요구된다. 본 연구에서는 Glycine, Alanine 등의 열역학적 저해제를 5, 10, 15 wt% 등으로 첨가하여 CO₂ 하이드레이트의 상평형 조건에 미치는 영향을 측정하였고, 각 물질을 12.5, 22.0 mmol%로 첨가하여 물질에 따라 상평형에 미치는 영향을 비교하여 보았다. 또한 Alanine의 두 가지 광학 이성질체를 같은 농도로 첨가하여 각 물질에 따라 상평형에 미치는 영향을 비교하였다.

A case of giant cell tumor of tendon sheath

( Ro Sa Kim ),( Bo Ram Kwon ),( Hae Young Choi ),( You Won Choi ),( Min Young Lee ),( Ji Yeon Byun ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.1

Giant cell tumor of tendon sheath (GCTTS) is a second most common tumor of the hand following the ganglion cyst. It presents a slowly growing subcutaneous nodule in the finger encapsulated by a collagenous capsule. GCTTS has benign course mostly with diagnosed as a localized form, but rare cases of malignant GCTTS have been reported. As incomplete excision increases recurrence rate and on recurrence the possibility of malignant transformation also increases. The average age of onset of GCTTS is middle-aged adults and the prevalent site is the volar surface of finger. An 85-year-old Korean female presented with skin colored hard nodule on dorsal surface of left 3rd DIP joint of finger, a slowly enlarging for several years. Histological examination showed a well encapsulated round lobule in the dermis with varied cellularity. The mass consisted of many mononuclear cells and spindle cells in fibrous stroma, and osteoclast-like giant cells and foamy macrophages were characteristic. There was no specific finding in the Von-Kossa stain and the level of serum uric acid was normal. The patient was diagnosed with GCTTS and referred to an orthopedic surgeon for an excision surgery. Herein, we report a rare case of GCTTS occurring in old age on dorsal surface of finger.