Hierarchically nanoporous pyropolymer nanofibers for surface-induced sodium-ion storage

Yoon, Hyeon Ji,Lee, Min Eui,Kim, Na Rae,Yang, Seung Jae,Jin, Hyoung-Joon,Yun, Young Soo Pergamon Press 2017 Electrochimica Acta Vol. No.

<P><B>Abstract</B></P> <P>Surface-driven charge storage materials based on both electrochemical double layer (EDL) formation and pseudocapacitive behavior can deliver high energy and power capabilities with long-lasting cycling performance. On the other hand, the electrochemical performance is strongly dependent on the material properties, requiring sophisticated electrode design with a high active surface area and a large number of redox-active sites. In this study, hierarchically nanoporous pyropolymer nanofibers (HN-PNFs) were fabricated from electrospun polyacrylonitrile nanofibers by simple heating with KOH. The HN-PNFs have a hierarchically nanoporous structure and an exceptionally high specific surface area of 3,950.7m<SUP>2</SUP> g<SUP>−1</SUP> as well as numerous redox-active heteroatoms (C/O and C/N ratio of 10.6 and 16.8, respectively). These unique material properties of HN-PNFs resulted in high reversible Na-ion capacity of ∼292mAhg<SUP>−1</SUP> as well as rapid kinetics and stable cycling performance in the cathodic potential range (1-4.5V vs. Na<SUP>+</SUP>/Na). Furthermore, energy storage devices based on HN-PNFs showed a remarkably high specific energy of ∼258 Wh kg<SUP>−1</SUP> at ∼245Wkg<SUP>−1</SUP> as well as a high specific power of ∼21,500Wkg<SUP>−1</SUP> at ∼78 Wh kg<SUP>−1</SUP>, with long and stable cycling behaviors over 2,000 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hierarchically nanoporous pyropolymer nanofibers (HN-PNFs) were fabricated. </LI> <LI> HN-PNFs have a high specific surface area of ∼3,950m<SUP>2</SUP> g<SUP>−1</SUP> and numerous heteroatoms. </LI> <LI> HN-PNFs exhibit high capacities of ∼292mAhg<SUP>−1</SUP> and great rate/cycling performances. </LI> <LI> High energy (258Whkg<SUP>−1</SUP>) and high power (21,500Wkg<SUP>−1</SUP>) are achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Hierarchically nanoporous pyropolymer nanofibers (HN-PNFs) fabricated from electrospun polyacrylonitrile nanofibers by simple heating with KOH exhibited high electrochemical performance for Na-ion storage.</P> <P>[DISPLAY OMISSION]</P>

HT-60강 용접부의 SCC 및 AE신호특성에 관한 연구

나의균,유효선,김훈 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.1

인공해수에서 HT-60강 용접부의 응력부식균열(SCC)과 음향방출(AE)신호특성을 알아보기 위하여 SCC와 AE실험을 동시에 실시하였으며, 양 실험결과를 상호 비교ㆍ분석하였다. 모재의 경우, -0.8V에서 보다 긴 파단수명을 보였고, 용해기구 등으로 인하여 -0.8V에 비해 -0.5V에서 AE가 많이 발생하였다. 그러나 시험편에 가해진 전위 값에 관계없이 최대하중 이후의 영역에서 AE 발생과 큰 진폭의 범위(40~100dB)를 나타내었으며 최대하중 이후에도 AE 발생이 활발하였다. 또한, 보다 크고 많은 균열이 파단면에 형성되었음을 SEM관찰을 통하여 관찰할 수 있었으며, 이들 결과로부터 용접부는 인공해수에서 SCC현상이 가장 심하게 일어나고 있음을 확인할 수 있었다. 후열처리는 용접부의 연화를 초래하였고, 용접재에 비해 부식환경에 대한 민감도를 떨어뜨리는 효과를 가져왔다. In order to characterize the microscopic fracture behaviour of the weldment during stress corrosion cracking(SCC) phenomena, SCC and acoustic emission(AE) tests were carried out simultaneously and the correlation between mechanical parameters obtained from SCC and AE tests was investigated. In the case of base metal, much more AE events were produced at -0.5V than at -0.8V because of the dissolution mechanism before the maximum load. Regardless of the applied voltages to the specimens, however, AE events decreased after the maximum load. In the case of weldment, lots of AE events with larger amplitude range(40~100dB) were produced because of the singularities of weld HAZ in comparison to the base metal and post-weld heat-treated (PWHT) specimens. Numerous and larger cracks for the weldment were observed on the fractured surfaces by SEM examination. From these results, it was concluded that SCC for the weldment appeared most severely in synthetic seawater. Weld HAZ was softened by PWHT which also contributed to the reduced susceptibility to corrosive environment in comparison to weldment.

음향방출법에 의한 고 장력강 용접부의 부식손상 특성 평가

나의균,김훈 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.3

본 연구의 목적은 음향방출법을 이용하여 고 장력강 용접부의 응력부식균열특성을 평가하는데 있다. 이를 위해 용접재와 후열처리재를 대상으로 인공해수에서 저 변형률로 하중을 가하면서 응력부식균열을 일으키고, 동시에 음향방출법에 의해 손상과정을 감시하였다. 부식환경은 전위계에 의해 제어되었으며, 시험편에는 각각 -0.8 V와 -1.1 V의 전위값을 가하였다. -0.8 V인 부식환경 하에서 일층 용접부는 후열처리재에 비해 단위 시간당 AE counts 수가 훨씬 많이 발생하였으며, 응력부식균열과정에서 균열의 발생 및 합체가 가장 활발하게 이뤄지고 있음을 누적 AE counts의 결과로부터 확인할 수 있었다. 가해진 전위 값이 -1.1 V인 경우, 일층 용접재의 파단시간은 이층 용접재에 비해 줄었고, AE counts수는 이층 용접재에 비해 현저히 많이 발생하였다. AE진폭 범위는 -0.8 V일층 용접재에서 가장 높았고, -1.1 V 일층 용접재에서 가장 작은 값을 보였는데, fractography분석결과 AE 진폭범위는 균열의 크기 및 폭과 밀접한 관계가 있음을 알 수 있었다. This study is to evaluate the characteristics of SCC at the welded region of high strength steel using acoustic emission(AE) method. Specimens were load by a slow strain rate method in synthetic seawater and the damage process was monitored simultaneously by AE method. Corrosive environment was controlled using the potentiostat, in which -0.8 Vand -1.1 V were applied to the specimens. In the case of one-pass weldment subjected to -0.8 V, much more AE counts were detected compared with the PWHT specimen. It was verified through the cumulative counts that coalescence of micro cracks and cracks for the one pass weldment with -0.8 V were mostly detected. In case of the one pass weldment subjected to -1.1 V, time to failure became shorter and AE counts were produced considerably as compared with that of the two pass weldment. It was shown that AE counts and range of AE amplitude have close relations with the number and size as well as width of the cracks which were formed during the SCC.

섬유종류 및 잔골재용적비에 따른 HPFRCC의 공학적 특성에 관한 실험적 연구

이의배,이동혁,나철성,조봉석,김재환,김무한 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)

In general, concrete showed brittle fracture but HPFRCC(High Performance fiber reinforced cementitious composite) showed ultra high ductile behavior in the hardened state, because of the fiber bridging properties. So a variety of experiments have being performed to access the performance of HPFRCC recently. In this study, to develope HPFRCC with high ductility and strain capacity, effects of fiber types and sand volume fraction were investigated. And results of this study were as follows; · HPFRCC reinforced with PVA or hybrid fiber were superior to PP or singleness. · Effect of sand volume fraction on HPFRCC reinforced with PP was insignificant.

열공형과 비열공형 피질하 혈관성 치매에서 위험인자의 차이에 관한 비교 연구

배희준,정지향,유경호,나덕렬,김상윤,최경규,양동원,손의주,이상도,김재우,박경원,김응규,이재홍,박미영,한일우,함동석,최문성,하충건,최성혜,이애영,이병철,한설희 대한치매학회 2003 Dementia and Neurocognitive Disorders Vol.2 No.2

Backgrounds and Objectives: Vascular dementia is a group of dementing disoders arising from various stroke syndrome. Among these. subcortical ischemic vascular dementia (SIVD) is regarded as a relatively distinct clinical entity. However, MRI patterns of SIVD are not homogenous. In some patients, lacunes are dominant, and in others, subcortical white matter changes are. This study was designed to compare risk factor profiles between SIVD with and without multiple lacunes. Methods: We divided 47 subjects (22 males, mean age. 68 years) recruited from VADAPET (Multicenter Trial For Evaluation Of The Changes In the PET Images Of Subcortical Vascular Dementia Patient) study into two groups one with more than 5 lacunes in deep gray matter (lacune group) and the other with 5 or less(non-lacune group) Clinical characteristics and laboratory findings of two groups were compared. Results: Nineteen of 47 patients (40%) belonged to the lacune group. The lacune and non-lacune groups d d not differ in the following variables: age, hypertension, diabetes mellitus, hyperlipidemia heart disease, history of stroke or TIA, history of trauma or major surgery, family history of hypertension stroke, or dementia, age at diagnosis of dementia, body mass index, white blood cell count, ESR, CRP, fibrinogen, hemoglobin A1C, total cholesterol. LDL cholesterol creatinine, proteinuria, glucosuria, and microhematuria. However, male sex, smoking alcohol. hemoglobin, and HDL cholesterol were possibly associated more with lacune group SIVD than with non-lacune group (p<0 1) Multivariate analyses revealed that smoking, hemoglobin, and HDL cholesterol were independent predictors of SIVD with multiple lacunes Conclusion: Our study suggests that SIVD with multiple lacunes may be significantly different in smoking habits hemoglobin, and HDL cholesterol from SIVD without multiple lacunes.

In vitro evaluation of histone deacetylase inhibitors as combination agents for colorectal cancer.

Kim, Jin C,Shin, Eui S,Kim, Chan W,Roh, Seon A,Cho, Dong H,Na, Young S,Kim, Tae W,Kim, Moon B,Hyun, Young L,Ro, Seonggu,Kim, Seon Y,Kim, Yong S Potamitis Press 2009 Anticancer research Vol.29 No.8

<P>BACKGROUND: Our primary aim was to evaluate the additive efficacy of histone deacetylase inhibitors (HDACIs) in established treatment regimens for colorectal cancer in concurrence with identifying the clinicopathological markers significantly associated with tumor responsiveness. PATIENTS AND METHODS: The chemosensitivities of 125 colorectal carcinomas to established regimens [FLOX (5-FU + leucovorin + oxaliplatin) and FLIRI (5-FU + leucovorin + irinotecan)], two biologically targeted drugs (avastin and erbitux), and two hydroxamic acid derivatives (vorinostat, SAHA(R), and a novel candidate, CG2) were comparatively evaluated using an in vitro tumor response assay. RESULTS: The response rates of tumors (inhibition rate > or =30%) were significantly greater for FLOX and combinations (55.2-68%) compared to FLIRI and combinations (44-63.2%) (p=0.001 to 0.048), except in the case of the CG2 combination. The additive effects of HDACIs on the respective established regimens were considerably greater for non-responsive tumors (64.3-80%) than responsive tumors (32.7-45%) (p< or =0.0001 to 0.008). A number of biological parameters, including less advanced tumors and p53 overexpression, were significantly associated with additive chemosensitivity to HDACIs in combination with FLOX and FLIRI in multivariate analyses (p< or =0.001 to 0.023). Expanding tumor growth, diffuse cytoplasmic carcinoembryonic antigen (CEA) expression and synchronous adenoma were associated with combination regimens with targeted drugs (p=0.013 to 0.032). CONCLUSION: Our findings show additive chemoresponsiveness of colorectal tumors to HDAC inhibitors in combination with established regimens. The significant parameters associated with combination regimens of targeted drugs and HDACIs may be applied as effective chemosensitive markers in future clinical trials.</P>

Bifidobacterium longum and Galactooligosaccharide Improve Skin Barrier Dysfunction and Atopic Dermatitis-like Skin

Kim Sukyung,Han Song-Yi,Lee Jinyoung,Kim Na-Rae,Lee Bora,Kim Hyunmi,Kwon Mijeoung,Ahn Kangmo,Noh Youngbae,Kim Sang Jong,Lee Phyrim,Kim Dongki,Kim Byung Eui,김지현 대한천식알레르기학회 2022 Allergy, Asthma & Immunology Research Vol.14 No.5

Purpose: The beneficial effects of a combination therapy using Bifidobacterium longum and galactooligosaccharide (GOS) for the treatment of atopic dermatitis (AD) have not been elucidated. Methods: Gene expressions of interleukin (IL)-4 and IL-13 from peripheral blood mononuclear cells and fecal abundance of B. longum from 12-month-old infants were evaluated. Human primary epidermal keratinocytes (HEKs) and hairless mice were treated with B. longum, GOS, B. longum-derived extracellular vesicles (BLEVs), dinitrochlorobenzene (DNCB), or a synbiotic mixture of B. longum and GOS. Expression of epidermal barrier proteins and cytokines as well as serum immunoglobulin E (IgE) levels were analyzed in HEKs and mice. Dermatitis scores, transepidermal water loss (TEWL), epidermal thickness, and fecal B. longum abundance were evaluated in mice. Results: Fecal abundance of B. longum was negatively correlated with blood IL-13 expression in infants. B. longum or BLEVs increased expression of filaggrin (FLG) and loricrin (LOR) in HEKs. B. longum increased the efficacy of GOS to upregulate FLG and LOR expressions in HEKs. Oral administration of GOS increased fecal abundance of B. longum in mice. Oral administration of B. longum attenuated DNCB-induced skin inflammation, abnormal TEWL, AD-like skin, and deficiency of epidermal barrier proteins. Moreover, the combination of B. longum and GOS showed greater effects to improve DNCB-induced skin inflammation, abnormal TEWL, AD-like skin, serum IgE levels, IL-4 over-expression, and the deficiency of epidermal barrier proteins than the administration of B. longum alone. Conclusions: B. longum and GOS improve DNCB-induced skin barrier dysfunction and AD-like skin.

Changes of Cytosolic $Ca^{2+}$ under Metabolic Inhibition in Isolated Rat Ventricular Myocytes

Kang, Sung-Hyun,Kim, Na-Ri,Joo, Hyun,Youm, Jae-Boum,Park, Won-Sun,Warda, Mohamed,Kim, Hyung-Kyu,Von Cuong, Dang,Kim, Tae-Ho,Kim, Eui-Yong,Han, Jin The Korean Society of Pharmacology 2005 The Korean Journal of Physiology & Pharmacology Vol.9 No.5

To characterize cytosolic $Ca^{2+}$ fluctuations under metabolic inhibition, rat ventricular myocytes were exposed to $200{\mu}M$ 2,4-dinitrophenol (DNP), and mitochondrial $Ca^{2+}$, mitochondrial membrane potential (${\Delta}{\Psi}m$), and cytosolic $Ca^{2+}$ were measured, using Rhod-2 AM, TMRE, and Fluo-4 AM fluorescent dyes, respectively, by Laser Scanning Confocal Microscopy (LSCM). Furthermore, the role of sarcolemmal $Na^+$/$Ca^{2+}$ exchange (NCX) in cytosolic $Ca^{2+}$ efflux was studied in KB-R7943 and $Na^+$-free normal Tyrode's solution (143 mM LiCl ). When DNP was applied to cells loaded with Fluo-4 AM, Fluo-4 AM fluorescence intensity initially increased by $70{\pm}10$% within $70{\pm}10$ s, and later by $400{\pm}200$% at $850{\pm}45$ s. Fluorescence intensity of both Rhod-2 AM and TMRE were initially decreased by DNP, coincident with the initial increase of Fluo-4 AM fluorescence intensity. When sarcoplasmic reticulum (SR) $Ca^{2+}$ was depleted by $1{\mu}M thapsigargin plus $10{\mu}M ryanodine, the initial increase of Fluo-4 AM fluorescence intensity was unaffected, however, the subsequent progressive increase was abolished. KB-R7943 delayed both the first and the second phases of cytosolic $Ca^{2+}$ overload, while $Na^+$-free solution accelerated the second. The above results suggest that: 1) the initial rise in cytosolic $Ca^{2+}$ under DNP results from mitochondrial depolarization; 2) the secondary increase is caused by progressive $Ca^{2+}$ release from SR; 3) NCX plays an important role in transient cytosolic $Ca^{2+}$ shifts under metabolic inhibition with DNP.

Protein Kinase C Activates ATP-sensitive Potassium Channels in Rabbit Ventricular Myocytes

Kim, Na-Ri,Youm, Jae-Boum,Joo, Hyun,Kim, Hyung-Kyu,Kim, Eui-Yong,Han, Jin The Korean Society of Pharmacology 2005 The Korean Journal of Physiology & Pharmacology Vol.9 No.4

Several signal transduction pathways have been implicated in ischemic preconditioning induced by the activation of ATP-sensitive $K^+$ $(K_{ATP})$ channels. We examined whether protein kinase C (PKC) modulated the activity of $K_{ATP}$ channels by recording $K_{ATP}$ channel currents in rabbit ventricular myocytes using patch-clamp technique and found that phorbol 12,13-didecanoate (PDD) enhanced pinacidil-induced $K_{ATP}$ channel activity in the cell-attached configuration; and this effect was prevented by bisindolylmaleimide (BIM). $K_{ATP}$ channel activity was not increased by $4{\alpha}-PDD$. In excised insideout patches, PKC stimulated $K_{ATP}$ channels in the presence of 1 mM ATP, and this effect was abolished in the presence of BIM. Heat-inactivated PKC had no effect on channel activity. PKC-induced activation of $K_{ATP}$ channels was reversed by PP2A, and this effect was not detected in the presence of okadaic acid. These results suggest that PKC activates $K_{ATP}$ channels in rabbit ventricular myocytes.

Notes : Isolation of Candida albicans Chitin Synthase 1 Inhibitor from Streptomyces sp. A6705 and Its Characterization

( Na Rae Kim ),( Eui Il Hwang ),( Bong Sik Yun ),( Sang Han Lee ),( Jae Sun Moon ),( Chi Hwan Lim ),( Se Jin Lim ),( Sung Uk Kim ) 한국미생물 · 생명공학회 2005 Journal of microbiology and biotechnology Vol.15 No.4