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Dynamics and Mechanism of Flame Retardants in Polymer Matrixes: Experiment and Simulation
Yoon, Donghwan,Jung, Hyun Tae,Kwon, Gyemin,Yoon, Yeoeun,Lee, Minsoo,Bae, Imhyuck,Joo, Beom Jun,Kim, Mansuk,Lee, Sun Ae,Lee, Jihye,Lee, Yeonhee,Cho, Eunseog,Shin, Kwanwoo,Sung, Bong June American Chemical Society 2013 The journal of physical chemistry. B, Condensed ma Vol.117 No.28
<P>We investigate the dynamics and the mechanism of flame retardants in polycarbonate matrixes to explore for a way of designing efficient and environment-friendly flame retardants. The high phosphorus content of organic phosphates has been considered as a requirement for efficient flame retardants. We show, however, that one can enhance the efficiency of flame retardants even with a relatively low phosphorus content by tuning the dynamics and the intermolecular interactions of flame retardants. This would enable one to design bulkier flame retardants that should be less volatile and less harmful in indoor environments. UL94 flammability tests indicate that even though the phosphorus content of 2,4-di-<I>tert</I>-butylphenyl diphenyl phosphate (DDP) is much smaller with two bulky tertiary butyl groups than that of triphenyl phosphate (TPP), DDP should be as efficient of a flame retardant as TPP, which is a widely used flame retardant. On the other hand, the 2-<I>tert</I>-butylphenyl diphenyl phosphate (2-<I>t</I>BuDP), with a lower phosphorus content than TPP but with a greater phosphorus content than DDP, is less efficient as a flame retardant than both DDP and TPP. Dynamic secondary ion mass spectrometry and molecular dynamics simulations reveal that the diffusion of DDP is slower by an order of magnitude at low temperature than that of TPP but becomes comparable to that of TPP at the ignition temperature. This implies that DDP should be much less volatile than TPP at low temperature, which is confirmed by thermogravimetric analysis. We also find from Fourier transform infrared spectroscopy that Fries rearrangement and char formation are suppressed more by DDP than by TPP. The low volatility and the suppressed char formation of DDP suggest that the enhanced flame retardancy of DDP should be attributed to its slow diffusivity at room temperature and yet sufficiently high diffusivity at high temperature.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2013/jpcbfk.2013.117.issue-28/jp400114x/production/images/medium/jp-2013-00114x_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp400114x'>ACS Electronic Supporting Info</A></P>
Basic : Lactococcus garvieae septicemia with Liver abscess in an immunocompetent patient (초)
( Sang Wook Lee ),( Hyung Joon Kim ),( Suh Yoon Yang ),( Hyun Woong Lee ),( Bong Ki Cha ),( Beom Jin Kim ),( Hyoung Chul Oh ),( Chang Hwan Choi ),( Jeong Wook Kim ),( Jae Hyuk Do ),( Jae Gyu Kim ),( S 대한간학회 2011 Clinical and Molecular Hepatology(대한간학회지) Vol.17 No.3(S)
Yoon, Seung-Bin,Choi, Seon-A,Sim, Bo-Woong,Kim, Ji-Su,Mun, Seong-Eun,Jeong, Pil-Soo,Yang, Hae-Jun,Lee, Youngjeon,Park, Young-Ho,Song, Bong-Seok,Kim, Young-Hyun,Jeong, Kang-Jin,Huh, Jae-Won,Lee, Sang-R Society for the Study of Reproduction [etc.] 2014 BIOLOGY OF REPRODUCTION Vol.90 No.5
<P>The stress produced by the coupling of reactive oxygen species (ROS) and endoplasmic reticulum (ER) has been explored extensively, but little is known regarding their roles in the early development of mammalian embryos. Here, we demonstrated that the early development of in vitro-produced (IVP) bovine embryos was governed by the cooperative action between ROS and ER stress. Compared with the tension produced by 5% O2, 20% O2 significantly decreased the blastocyst formation rate and cell survival, which was accompanied by increases in ROS and in levels of sXBP-1 transcript, which is an ER stress indicator. In addition, treatment with glutathione (GSH), a ROS scavenger, decreased ROS levels, which resulted in increased blastocyst formation and cell survival rates. Importantly, levels of sXBP-1 and ER stress-associated transcripts were reduced by GSH treatment in developing bovine embryos. Consistent with this observation, tauroursodeoxycholate (TUDCA), an ER stress inhibitor, improved blastocyst developmental rate, trophectoderm proportion, and cell survival. Moreover, ROS and sXBP-1 transcript levels were markedly decreased by supplementation with TUDCA, suggesting a possible mechanism governing the mutual regulation between ROS and ER stress. Interestingly, knockdown of XBP-1 transcripts resulted in both elevation of ROS and decrease of antioxidant transcripts, which ultimately reduced in vitro developmental competence of bovine embryos. Based on these results, in vitro developmental competence of IVP bovine embryos was highly dependent on the coupled response between oxidative and ER stresses. These results increase our understanding of the mechanism(s) governing early embryonic development and may improve strategies for the generation of IVP embryos with high developmental competence.</P>
Chronic Osteomyelitis of the Lumbar Transverse Process
Bong-Jin Lee,Seong-Tae Kim,Min Geun Yoon,Sung-Soo Kim,문명상 대한정형외과학회 2011 Clinics in Orthopedic Surgery Vol.3 No.3
Pyogenic spondylitis involving only the posterior element of a vertebra is rare. To the best of our knowledge, there have been noreports of osteomyelitis of the transverse process. We report here on a 45-year-old male with a one month history of swelling associatedwith lower back pain. The magnetic resonance imaging showed a paraspinal soft tissue mass, and computed tomographyrevealed a fi ne osteolytic lesion in the right transverse process of the 5th lumbar spine, and this was all consistent with chronicosteomyelitis. A mixed staphylococcal infection was identifi ed. Open drainage, resection of the transverse process and intravenousinjection of anti-staphylococcal antibiotics resolved the back pain and reduced the erythrocyte sedimentation rate to normal. Pyogenic osteomyelitis of the transverse process is extremely rare, which can cause a misdiagnosis or a delayed diagnosis. Carefulconsideration of this disease is needed when evaluating patients who complain of back pain.
Facile graphene n-doping by wet chemical treatment for electronic applications.
Bong, Jae Hoon,Sul, Onejae,Yoon, Alexander,Choi, Sung-Yool,Cho, Byung Jin RSC Pub 2014 Nanoscale Vol.6 No.15
<P>We report a post-synthetic n-doping method for chemical-vapor-deposition (CVD) grown graphene using wet chemical processing. An ammonium fluoride solution was found effective in converting pristine hole doping into electron doping in addition to the mobility improvement of charge carriers. We verified the doping by electrical measurements, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses and suggest that the mechanism of n-doping is electrostatic doping by ionic physisorption of ammonium ions on the graphene surface. This simple chemical doping method provides a facile and robust route to n-doping of large area graphene for the realization of high performance graphene-based electronic devices.</P>
A Design of the Frequency Synthesizer for UWB Application in 0.13 µm RF CMOS process
Sung-Kyu Jung,Jin-Kyung Kim,Ji-Hoon Jung,Kang-Yoon Lee,Chul Nam,Bong-Hyuk Park,Sang-sung Choi 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
This paper describes a 3 to 5㎓ frequency synthesizer for MB-OFDM UWB application using 0.13um CMOS process. The frequency synthesizer operates in the band group1 whose center frequencies are 3432㎒, 3960㎒, and 4488㎒. To cover the overall frequencies of group 1, an efficient frequency planning minimizing a number of blocks and the power consumption are proposed. And, a high-frequency VCO and prescaler architecture are also presented in this paper. A new coarse tuning scheme that utilizes the MIM capacitance and the varactor is proposed to expand the VCO tuning range. The single PLL and two SSB-mixers consume 75㎽ from a 1.5V supply. The VCO tuning range is 500㎒. The simulated phase noise of the VCO is -110㏈c/Hz at 1㎒ offset. The die area is 3 × 2㎟.
Yoon, Sang Eun,Kang, Yeongkwon,Noh, So Yeon,Park, Jeongwoo,Lee, Sang Yeon,Park, Jaehong,Lee, Dae Woon,Whang, Dong Ryeol,Kim, Taekyeong,Kim, Gun-Ho,Seo, Hyungtak,Kim, Bong-Gi,Kim, Jong H. American Chemical Society 2020 ACS APPLIED MATERIALS & INTERFACES Vol.12 No.1
<P>Intercorrelation of thermoelectric properties of a doped conjugated semiconducting polymer (PIDF-BT) with charge carrier density, conductive morphology, and crystallinity are systematically investigated. Upon being doped with F4-TCNQ by the sequential doping method, PIDF-BT exhibited a high electrical conductivity over 210 S cm<SUP>-1</SUP>. The significant enhancement of electrical conductivity resulted from a high charge carrier density, which is attributed to the effective charge-transfer-based integer doping between PIDF-BT and dopant molecules. Based on the systemic characterization on the optical, electrical, and structural properties of doped PIDF-BT annealed at different temperatures, we investigated the characteristic correlations between thermoelectric properties of PIDF-BT films and their four-probe electrical conductivity, charge carrier density, and charge carrier mobility obtained from AC Hall effect measurements. This study revealed that exercising fine control over the crystallinity and conductive migration of the conjugated polymer films can be a strategic approach to suppressing the degradation of the Seebeck coefficient at high charge carrier density and ultimately to maximizing the power factors of organic thermoelectric devices.</P> [FIG OMISSION]</BR>
( Yoon Soo Kim ),( In-ho Bae ),( Chan-ho Na ),( Bong-seok Shin ),( Min-sung Kim ) 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.2
Background: Various therapeutical approaches for wart are possible, depending on age, sex, immune status, extension of the body and severity of lesion. .Recently intralesional immunotherapy by MMR vaccine has shown good effect among the nondestructive treatment. Two MMR vaccines, M-M-R II<sup>®</sup> (Merck & Co.) and Priorix<sup>®</sup> (GlaxoSmithKline) have been used for vaccination in Korea. However, the two vaccines contain different strains, and Priorix was developed more recently. Objectives: This study is to compare the effect of intralesional immunotherapy using M-M-R II<sup>®</sup> and Priorix<sup>®</sup> Methods: A retrospective study was performed, and we enrolled 380 patients with various types of warts into the study, which was for a duration of 6 years. Depending on the decrease in wart size, response to treatment was classified into three categories; CR(100%), partial response (PR)(50-99%) and no response (NR) (<50%). Patients were treated for at least three times every two weeks from injection therapy was performed up to five times. Results: Over half (64.25%) of patients experienced > 50% reduction in the size and number of warts treated with Priorix<sup>®</sup>. On the other intralesional immunotherapy using M-M-R II<sup>®</sup> was less than half (45.66%). Conclusion: We suggest that intralesional immunotherapy with Priorix<sup>®</sup> more effective than using M-M-R II<sup>®</sup>. This is thought to be due to antigenic polymporphisms in each vaccine strain produce strain-specific immunity.