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Atomic Hydrogen Productionfrom Semi-clathrate Hydrates
Koh, Dong-Yeun,Kang, Hyery,Park, Juwoon,Shin, Woongchul,Lee, Huen American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.12
<P>Atomic hydrogen has received recent attention because of its potential role in energy devices, silicon devices, artificial photosynthesis, hydrogen storage, and so forth. Here, we propose a highly efficient route for producing atomic hydrogen using semi-clathrate hydrates. Two major hydrogen radical sources, derived from guest/host materials, are closely examined.</P>
Tuning Cage Dimension in Clathrate Hydrates for Hydrogen Multiple Occupancy
Koh, Dong-Yeun,Kang, Hyery,Jeon, Jiwon,Ahn, Yun-Ho,Park, Youngjune,Kim, Hyungjun,Lee, Huen American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.6
<P>As hydrogen molecules enter the clathrate hydrate body, the ubiquitous dodecahedral cavity (5<SUP>12</SUP>) is too small to allow anything but single occupancy thermodynamically. The possibility that H<SUB>2</SUB> double occupancy can occur in the dodecahedral cavity has been suggested and is still under debate. Here we uncover the unique feature of multiple occupancy of the hydrogen molecule in a dodecahedral cavity as induced by tuning the cage dimensions. The guest promoter population in the hydrate matrix spontaneously controls the degree of molecular hydrogen storage by tuning the cage dimensions. Our analysis combined with computational study reveals that only ∼1% expansion (∼3% in volume) of the cage dimensions is sufficient to provide thermodynamically stable room for double occupancy in the dodecahedral cavity. The findings in this research provide a strategy for doubling the hydrogen population in dodecahedral cavities in structure II hydrates.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-6/jp410632q/production/images/medium/jp-2013-10632q_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp410632q'>ACS Electronic Supporting Info</A></P>
Tuning magnetism via selective injection into ice-like clathrate hydrates
박영준,Dong-Yeun Koh,Joonghoe Dho,연순화,Huen Lee 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.5
Clathrate hydrates exhibit unique intermolecular interactions between host-guest and guest-guest molecules because they have 3-dimensional superstructures consisting of the sublattices created by hydrogen-bonded water molecules that form cage-like frameworks in which guest molecules can be incorporated. Lattice engineering or molecular engineering using a selective injection of specific guest molecules into these sublattices can be exploited to tune the physicochemical properties of guest molecules or to create new functional materials. Here, we report distinctive intermolecular behavior of oxygen molecules that are selectively inserted in a structure-II type superstructure consisting of a tetrahedral sublattice by the small 512 water cages and a diamond-like sublattice by the large 51264 cages. Pure O2 clathrate hydrate and binary THF+O2 clathrate hydrate were synthesized, and their magnetism and heat capacity were measured at low temperature conditions. These results strongly suggest that the magnetic property of the oxygen molecule is largely varied with the formation of a 3-dimensional superstructure by the injection of O2 into the water frameworks.
Seol, Jiwoong,Koh, Dong‐,Yeun,Cha, Minjun,Shin, Woongchul,Lee, Young‐,Joo,Kim, Ji‐,Hoon,Lee, Jaehyoung,Lee, Huen Wiley Subscription Services, Inc., A Wiley Company 2012 AIChE Journal Vol.58 No.1
<P><B>Abstract</B></P><P>Anomalous chloride concentration enrichment has been detected in marine sediments comprising methane hydrates (MHs). In this study, we designed an electric circuit system linked to the high‐pressure resistance cell in which the chloride ion concentration can be directly measured within reliable accuracy under <I>in situ</I> conditions of the deep‐sea floor pressure and temperature. Chloride concentration increased under a fast MH formation rate, but no noticeable concentration change was detected under a relatively low‐rate. Furthermore, we suggested that the MH formation rate must be maintained at least ∼10<SUP>2</SUP> mol m<SUP>−2</SUP> yr<SUP>−1</SUP> so as to efficiently enrich chlorides and retain the acquired chlorinity. The present experimental system dose not fully reflect the relatively minor effective variables such as vertical advections in real system, but the results seem to be sufficient for revealing chloride enrichment phenomena induced by fast MH formation rate with free methane gas. © 2011 American Institute of Chemical Engineers AIChE J, 2012</P>
Effect of Molecular Nitrogen on Multiple Hydrogen Occupancy in Clathrate Hydrates
Park, Seongmin,Koh, Dong-Yeun,Kang, Hyery,Lee, Jae W.,Lee, Huen American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.35
<P>Multiple H<SUB>2</SUB> occupancy in confined cages has been explored for the purpose of enhancing storage capacity. Furthermore, balancing the formation pressure with high storage capacity is one of the most significant factors. Here, we demonstrate the use of binary (LGM + N<SUB>2</SUB>) hydrates to capture hydrogen clusters under relatively mild conditions, even observing double H<SUB>2</SUB> occupancy in small cages. The cage occupancy and structures of hydrates were identified by the Raman spectroscopic analysis and high-resolution powder diffraction. The reaction product of binary (LGM + N<SUB>2</SUB>) hydrates with H<SUB>2</SUB> molecules suggests the possibility of multiple H<SUB>2</SUB> occupancy in both small (5<SUP>12</SUP>) and large (5<SUP>12</SUP>6<SUP>4</SUP>) cages at relatively low pressures. Also, the lattice parameter decreases with an increase in H<SUB>2</SUB> occupancy. The unique and abnormal role of N<SUB>2</SUB> as a preoccupied coguest significantly affects the H<SUB>2</SUB> population in a crystalline hydrate matrix and further lowers the pressure for structure stabilization.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-35/jp5061254/production/images/medium/jp-2014-061254_0008.gif'></P>
Elbow Reconstruction Using Island Flap for Burn Patients
Hur, Gi Yeun,Song, Woo Jin,Lee, Jong Wook,Lee, Hoon Bum,Jung, Sung Won,Koh, Jang Hyu,Seo, Dong Kook,Choi, Jai Ku,Jang, Young Chul Korean Society of Plastic and Reconstructive Surge 2012 Archives of Plastic Surgery Vol.39 No.6
Background Deep burns of the elbow lead to soft tissue necrosis and infection, with exposure of deep structures. Adequate wound coverage of this area requires thin, pliable, and durable tissue, while optimal functional recovery requires early coverage and functional rehabilitation. We have found 3 types of island flaps that provide reliable coverage for the elbow. Methods A retrospective study was performed on all patients who underwent flap coverage of an elbow defect at our hospital. The patients' data including age, sex, cause of injury, wound dimensions, timing of flap coverage, postoperative elbow motion, and complications were investigated. Results Between 2001 and 2012, 16 patients were treated at our hospital. The mean age was 53.3 years. Three kinds of flaps were performed: 9 latissimus dorsi flaps, 4 lateral arm flaps, and 4 radial forearm flaps. The average defect size was 183.5 $cm^2$ (range, 28 to 670 cm2). Wound coverage was performed at mean duration of 45.9 days (range, 14 to 91 days). The mean postoperative active elbow flexion was $98^{\circ}$ (range, $85^{\circ}$ to $115^{\circ}$). Partial flap failure occurred in 1 latissimus dorsi flap. Minor complications included partial flap loss (11.8%), hematoma (23.5%), seroma (35.3%), and wound infection (5.9%). Conclusions Flap selection for elbow reconstruction is determined by the defect size and the extent of the adjacent tissue injury. Elbow reconstruction using an island flap is a single-staged, reliable, and relatively simple procedure that permits initiation of early rehabilitation, thereby improving a patient's functional outcome.
내과계 중환자실에 입원한 객혈 환자들에 있어 APACHE 3 점수 체계의 예후적 가치에 관한 연구
양성연(Sung Yeun Yang),고윤석(Youn Suck Koh),임채만(Chae Man Lim),이무송(Moo Song Lee),유미란(Mi Ran Yoo),최강현(Gang Heun Choi),이상도(Sang Do Lee),김우성(Woo Sung Kim),김동순(Dong Soon Kim),김원동(Won Dong Kim) 대한내과학회 1997 대한내과학회지 Vol.53 No.3
Background: Massive hemoptysis is one of the major medical emergency with high risk of mortality. Though the best predictor of mortality associated with hemoptysis appears to be the amount of bleeding within the first 24 hours, catastrophic hemorrhage could be occurred to the patients who were apparently in a stable condition with scanty hemoptysis at the time of admission. We evaluated APACHE III score system to find if it could be a prognostic index that can predict the mortality of the patients with hemoptysis. Methods : We identified all the patients who had admitted with hemoptysis in the Medical Intensive Care Unit of Asan Medical Center between May 25, 1989, and July 31, 1995. A retrospective analysis was done in 66 patients with hemoptysis on APA- CHE III score. Results: The overall mortality rate was 17.4% (12/69). In univariate analysis of possible prognostic factors, independent predictors of mortality were age(P=0.016), amount of hemoptysis(P=0.012), AaDO2 (P=0.017), requirement of transfusion(P=0.036), mechanical ventilatory care(P<0.05) and APACHE III score(P=0.02), In multivariate analysis with sex, age, amount of hemoptysis, AaDO2, requirement of transfusion and APACHE III score, APACHE III score was the only independent predictor of mortality(P=0.015, odd ratio=19.3, 95% confidence interval, 3.4 to 249.7) Conclusion: APACHE IU score may be a clinically significantly important independent predictor of outcome in the patients with hemoptysis. In addition, invasive procedure, such as bronchial artery embolizaticn or operation, could be considered in advance in the patients with more than 30 points of APACHE III.