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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>
Yun, Young Soo,Kim, Yu Hyun,Song, Min Yeong,Kim, Na Rae,Ku, Kyojin,An, Ji Su,Kang, Kisuk,Choi, Hyoung Jin,Jin, Hyoung-Joon Elsevier 2016 Journal of Power Sources Vol.331 No.-
<P><B>Abstract</B></P> <P>Nanostructured pyropolymers contain significant amounts of redox-active heteroatoms, have high specific surface areas, and a defective carbon microstructure, indicating good potential for pseudocapacitive charge storage. In this study, nitrogen-enriched pyropolymer nanoparticles (N-PNs-50) are fabricated from polyaniline nanotubes through rapid pyrolysis at 50 °C min<SUP>−1</SUP>. N-PNs-50 exhibit a nitrogen content of 9.8 wt%, a high specific surface area of 875.8 m<SUP>2</SUP> g<SUP>−1</SUP>, and an amorphous carbon structure with an I<SUB> <I>D</I> </SUB>/I<SUB> <I>G</I> </SUB> intensity ratio of 0.95. These unique characteristics lead to good electrochemical performances, in which reversible capacities of 660 and 255 mAh g<SUP>−1</SUP> are achieved for Li-ion and Na-ion storage, respectively, with favorable voltage characteristics (<1.5 V for Li-ions and <1.2 V for Na-ions). This study provides a more feasible production method for nitrogen-doped pyropolymers and their practicable electrochemical performances for use as an anode in energy storage devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanostructured pyropolymers (N-PNs-50) were fabricated by rapid pyrolysis. </LI> <LI> N-PNs-50 exhibited a nitrogen content of 9.8 wt% and amorphous carbon structure. </LI> <LI> N-PNs-50 exhibited a high specific surface area of 875.8 m<SUP>2</SUP> g<SUP>−1</SUP>. </LI> <LI> 660 and 255 mAh g<SUP>−1</SUP> were achieved for Li-ion and Na-ion storage, respectively. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Nitrogen-enriched pyropolymer nanoparticles (N-PNs-50) were fabricated from polyaniline nanotubes through rapid pyrolysis at 50 °C min<SUP>−1</SUP>, showing superior electrochemical performances.</P> <P>[DISPLAY OMISSION]</P>
장세진,고상백,강동묵,김성아,강명근,이철갑,정진주,조정진,손미아,채창호,김정원,김정일,김형수,노상철,박재범,우종민,김수영,김정연,하미나,박정선,이경용,김형렬,공정옥,김인아,김정수,박준호,현숙정,손동국 大韓産業醫學會 2005 대한직업환경의학회지 Vol.17 No.4
Background and Purposes: Over the past three decades, numerous studies performed in Korea have reported that job stress is a determinant risk factor for chronic diseases and work disability. Every society has its own culture and occupational climate particular to their organizations, and hence experiences different occupational stress. An occupational stress measurement tool therefore needs to be developed to estimate it objectively. The purpose of this study is to develop and standardize the Korean Occupational Stress Scale (KOSS) which is considered to be unique and specific occupational stressors in Korean employees. Subjects and Methods: Data were obtained from the National Study for Development and Standardization of Occupational Stress (NSDSOS Project: 2002-2004). A total of 12,631 employees from a nationwide sample proportional to the Korean Standard Industrial Classification and the Korean Standard Occupational Classification were administered. The KOSS was developed for 2 years (2002-2004). In the first year, we collected 255 items from the most popular job stress measurement tools such as JCQ, ERI, NIOSH and OSI, and 44 items derived from the a qualitative study (depth interview). Forty-three items of KOSS, in the second year, were retained for use in the final version of the KOSS by using Delphi and factor analysis. Items were scored using conventional 1-2-3-4 Likert scores for the response categories. Results: We developed eight subscales by using factor analysis and validation process: physical environment (3 items), job demand (8 items), insufficient job control (5 items), interpersonal conflict (4 items), job insecurity (6 items), organizational system (7 items), lack of reward (6 items), and occupational climate (4 items). Together they explained 50.0% of total variance. Internal consistency alpha scores were ranged from 0.51 to 0.82. Twenty-four items of the short form of the KOSS (KOSS-SF) were also developed to estimate job stress in the work setting. Because the levels of the subscales of occupational stress were gender dependent, gender-specific standard norms for both the 43-item full version and the 24-item short form using a quartile for the subscales of KOSS were presented. Conclusion: The results of this study suggest that KOSS might be an appropriate measurement scale to estimate occupational stress of Korean employees. Further and more detailed study needs to be conducted to improve the validity of this scale.
세라믹 브라켓의 제거 시 Er : YAG 레이저의 효능
서충환,장나영,채종문,조진형,김상철,강경화 대한치과교정학회 2009 대한치과교정학회지 Vol.39 No.4
본 연구에서는 세라믹 브라켓 제거에 Er:YAG 레이저 조사가 도움이 되는지 알아보고, 브라켓 제거에 적합한 레이저 조사 방법을 연구하였으며, 또 이렇게 적용된 레이저가 치수와 법랑질에 손상을 주는지도 알아보았다. 총 190개의 치아, 단결정 세라믹 브라켓(MISO), 다결정 세라믹 브라켓(Transcend series 6000)과 KEY Laser3를 사용하였다. 실험군은 세라믹 브라켓의 종류(단결정, 다결정)와 레이저의 에너지(140, 300, 450, 600 mJ)에 따라 분류하였으며, 레이저를 브라켓당 두 곳에 1펄스씩 조사하고, 전단 강도를 측정하였다. 대조군은 레이저를 조사하지 않는 군으로 하였다. 레이저 조사에 의한 열 효과는 브라켓 하방 법랑질과 치수강에서 측정하였으며, 전단 강도 측정 후 치면에 남아있는 접착제의 양을 접착제 잔류 지수(adhesive remnant index)를 이용하여 평가하였다. 레이저 조사로 인한 접착제의 파괴 양상과 법랑질 표면 변화를 주사전자현미경으로 관찰하였다. 모든 세라믹 브라켓군에서 레이저 에너지가 증가 할수록 전단 강도는 유의하게 감소하였다. 또한, 브라켓 하방 법랑질에서 최대 온도 변화는 평균 3.78˚C 상승에 그쳤으며, 치수강에서 최대 온도 변화는 평균 0.9˚C 상승에 그쳤다. 주사전자현미경을 이용한 법랑질과 접착제 단면 관찰에서 접착제 표면이 레이저에 의해 붕괴되어 분화구 모양의 구덩이로 관찰되었으며, 일부 시편에서 약 10 - 30μm의 법랑질 손상이 발견되었다. Transbond XT로 부착된 단결정 도재 브라켓(MISO)의 디본딩에 Er:YAG 레이저를 이용할 경우, 300 - 450 mJ의 레이저 에너지를, 그리고 다결정 도재 브라켓(Transcend series 6000)의 경우는 450 mJ 정도의 에너지를 사용하는 것이 효과적이고 안전할 것으로 생각된다. Objective: The aim of this study was to find out whether Er:YAG laser can aid in debonding ceramic brackets, and to see what kind of method will be the most appropriate for debonding. Methods: One hundred and ninety teeth, monocrystalline brackets (MISO, HT, Ansan-Si, Korea), polycrystalline brackets (TranscendTM series 6000, 3M Untek, Monrovia, CA, USA) and the KEY Laser3 (KavoDental, Biberach, Germany) were used. Experimental groups were classified according to the type of ceramic brackets, and the amount of laser energy (0, 140, 300, 450, 600 mJ). After applying laser on the bracket at two points at 1 pulse each, the shear bond strength was measured. The effect of heat caused by laser was measured at the enamel beneath the bracket and pulp chamber. After measuring the shear bond strength, adhesive residue was evaluated and enamel surface was investigated using SEM. Results: All ceramic bracket groups showed a significant decrease in shear bond strength as the laser energy increased. The greatest average temperature change was 3.78˚C on the enamel beneath the bracket and 0.9˚C on the pulp chamber. Through SEM, crater shape holes caused by the laser was seen on the enamel and adhesive surfaces. Conclusions: If laser is applied on ceramic brackets for debonding, 300 - 450 mJ of laser energy will be safe and efficient for monocrystalline brackets (MISO), and about 450 mJ for polycrystalline brackets (Transcend series 6000).
( Hyoung Min Na ),( Chang Jin Jung ),( Joon Min Jung ),( Woo Jin Lee ),( Chong Hyun Won ),( Sung Eun Chang ),( Mi Woo Lee ) 대한피부과학회 2021 대한피부과학회 학술발표대회집 Vol.72 No.2
Primary cutaneous marginal zone lymphoma is an indolent B-cell lymphoma of the skin, occasionally showing significant T-cell infiltration with some extent of cytologic atypia. However, as there have been several reports of progression of T-cell lymphoma within the background of primary cutaneous marginal zone lymphoma, it is important to clarify whether the T-cell infiltrates present in T-cell-rich primary cutaneous marginal zone lymphoma are malignant or not. We report a case of cutaneous marginal zone lymphoma with the coexistence of T-cell-rich angiomatoid polypoid pseudolymphoma on the face of a Korean girl.