Structural, magnetic and dielectric properties of (Li1+, Al3+) co-doped Ni0.5Zn0.5Fe2O4 ferrite ceramics prepared by the sol-gel auto-combustion method

Qing Ni,Li Sun,Ensi Cao,Wentao Hao,Yongjia Zhang,Lin Ju 한국물리학회 2020 Current Applied Physics Vol.20 No.9

(Li1+, Al3+) co-doped Ni0.5Zn0.5Fe2O4 ferrites, Ni0.5-xZn0.5-xLixAlxFe2O4 (x = 0.000, 0.025, 0.050 and 0.100), were synthesized by the sol-gel auto-combustion method. X-ray diffraction (XRD), field emission scanning electronic microscope (FESEM), vibrating sample magnetometer (VSM) and LCR meter were used to investigate the structural, magnetic and dielectric properties. Results of XRD and SEM indicate that both doping amount and calcination temperature play significant roles in crystal structure and grain growth. Also, it can be observed that the saturation magnetization and the coercivity change in a noticeable manner. The Ni0.475Zn0.475Li0.025Al0.025Fe2O4 ferrite sintered at 1200 °C has a relatively low coercivity value (62.93 Oe) and the largest saturation magnetization (110.95 emu/g). Besides, dielectric behavior is also improved by Li1+ and Al3+ co-doping

Low-Temperature Carbon Coating of Nanosized Li_1.015Al_0.06Mn_1.925O₄ and High-Density Electrode for High-Power Li-Ion Batteries

Lee, Min-Joon,Lho, Eunsol,Bai, Peng,Chae, Sujong,Li, Ju,Cho, Jaephil American Chemical Society 2017 NANO LETTERS Vol.17 No.6

<P>Despite their good intrinsic rate capability, nanosized spinel cathode materials cannot fulfill the requirement of high electrode density and volumetric energy density. Standard carbon coating cannot be applied on spinel materials due to the formation of oxygen defects during the high-temperature annealing process. To overcome these problems, here we present a composite material consisting of agglomerated nanosized primary particles and well-dispersed acid treated Super P carbon black powders, processed below 300 degrees C. In this structure, primary particles provide fast lithium ion diffusion in solid state due to nanosized diffusion distance. Furthermore, uniformly dispersed acid-treated Super P (ASP) in secondary particle facilitates lower charge transfer resistance and better percolation of electron. The ASPLMO material shows superior rate capability, delivering 101 mAh g 1 at 300 degrees C-rate at 24 degrees C, and 75 mAh g(-1) at 100 degrees C-rate at 10 degrees C. Even after 5000 cycles, 86 mAh ClIcan be achieved at 30 degrees C=rate at 24 degrees C, demonstrating very competitive full-cell performance.</P>

인터넷에서의 부모교육 관련 사이트 현황분석

주리아,김희진 이화여자대학교 사범대학 교과교육연구소 2001 교과교육학연구 Vol.5 No.1

본 연구의 목적은 부모교육 관련 사이트 및 상담실의 운영관리 실태와 상담내용을 파악하는 것이다. 2000년 7월 15일부터 9월 15일까지 2달 동안 검색한 140개의 사이트를 살펴본 결과 첫째, 부모교육 관련 사이트는 다양한 운영자들에 의해 운영되고 있었고, 무료로 이용할 수 있었으며, 회원이 아니어도 정보를 사용할 수 있었으나 업데이트는 거의 이루어지지 않았다. 둘째, 상담실에는 검색기능이 있었으며 대부분 일주일 이내에 답변이 이루어 졌다. 상담자는 대부분 전문가로 기입되어 있으나 전문가의 약력 표시가 없어 전문성을 판단할 수 없는 경우가 많았다. 부모들은 자녀의 사회·정서발달에 관한 상담을 가장 많이 하였다. The aim of this study was to analyze the current status of parent education websites serving for the parents of 0- to 7-year-old children on the internet. One-hundred forty parent education websites were analyzed in terms of their management strategies and the topics of counseling. The results of this study were as follows: First, parent education websites were operated by diverse entities. Second, all of the sites provided their services for free and most of them open the services to non-registered users. However, of the 140 websites, only a few were updated. Third, the search function was available to all the sites and responses to the parents' questions were made within a week in most cases. Fourth, experts, although their backgrounds were unclear, in various fields participated in counseling with parents through internet. Finally, parents show much interest in socioemotional development of their children.

한문 복합월의 됨됨이 연구

박유리 동아대학교 어학연구소 1998 언어와 언어교육 Vol.13 No.-

Abstract In this study Chinese complex sentence is divided into 'compound sentence' and 'coordinate sentence', and these are compared with the aspects of Korean complex sentence. 'Compound sentence' is composed of 'main/root clause' and 'subordinate/embedded clause', and the structure of 'subordinate /embeddedclause' is studied in this paper. There are two kinds of 'subordinate/embeddedclause' in Chinese : the predicate in one kind has the grammatical element Ø, the predicate in the other kind the grammatical elements such as '者', '所', '之', and '而'. 'Coordinate sentence' consists of 'precedented clause - connected clause - concluded clause'. Unlike connection by ending('-고', '-니', '-며') in Korea, Chinese 'coordinate sentence' has two sorts as follows: one has conjunction between the two parts, the other has Ø conjunction.

강선 이음형 PC 보-기둥 내부 접합부의 구조적 거동에 관한 실험적 연구

하상수,김승훈,문정호,이리형,임주혁 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)

In this study, new moment-resisting precast concrete beam-column joint is proposed for moderate seismic regions. it is attempt to devise connection detail which makes workability improve and confirm effective stress transfer in the region of connection. It has the connection details which help working process simplified and construction cost reduced. as replace 9.3㎜, 7strand for reinforcement. Fore specimens for partial tension test and three specimens for beam-column interior joint test were producted. An experimental study was carried out to investigate the joint behavior subjected to reverse cyclic loading and constant axial compressive load. The test variables was transverse reinforcement in joint. Structural performance of joint is evaluated on the basis of connection strength, stiffness, energy dissipation, and drift capacity. Based on the test results, the precast connection is capable of matching or exceeding the performance of the monolithic connection and thereby provides the sufficient moment-resisting behavior to be applicable for moderate seismic regions.

Fe@C₂N: A highly-efficient indirect-contact oxygen reduction catalyst

Mahmood, Javeed,Li, Feng,Kim, Changmin,Choi, Hyun-Jung,Gwon, Ohhun,Jung, Sun-Min,Seo, Jeong-Min,Cho, Sung-June,Ju, Young-Wan,Jeong, Hu Young,Kim, Guntae,Baek, Jong-Beom Elsevier 2018 Nano energy Vol.44 No.-

<P><B>Abstract</B></P> <P>Converting unstable earth-abundant group VIIIB transition metals into stable catalysts with high oxygen reduction reaction (ORR) performances remains a critical challenge for electrochemical technologies. Iron (Fe)-nitrogen (N)-carbon (C)-based electrocatalysts have recently demonstrated ORR performances comparable to platinum (Pt)-based catalysts. However, as their poor stability remains a critical issue, which needs to be resolved to satisfy commercial requirements. Here, we describe a methodology for preparing a high-performance and stable Fe-based ORR catalyst. The catalyst was obtained by the <I>in-situ</I> sandwiching of a Fe<SUP>3+</SUP> precursor in a nitrogenated holey two-dimensional network (denoted as C<SUB>2</SUB>N). Reduction of the sandwiched Fe<SUP>3+</SUP> results in the formation of Fe oxide (Fe<SUB>x</SUB>O<SUB>y</SUB>) nanoparticles, which are simultaneously transformed into highly crystalline Fe<SUP>0</SUP> nanoparticle cores, while the C<SUB>2</SUB>N is catalysed into well-defined, encapsulating, nitrogenated graphitic shells (Fe@C<SUB>2</SUB>N nanoparticles) during heat-treatment. The resultant Fe<SUP>0</SUP>@C<SUB>2</SUB>N nanoparticles are uniformly distributed on the C<SUB>2</SUB>N substrate, becoming the Fe@C<SUB>2</SUB>N catalyst, which displayed ORR activities superior to commercial Pt/C in both acidic and alkaline media. Furthermore, the Fe@C<SUB>2</SUB>N catalyst remained rust-free during harsh electrochemical testing even after 650h, suggesting that its unusual durability originates from indirect-contact electrocatalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Iron (Fe) nanoparticle cores encapsulated in electrochemically transparent and stable shells (Fe@C<SUB>2</SUB>N) are prepared. </LI> <LI> The Fe@C<SUB>2</SUB>N catalyst displays superb oxygen reduction (ORR) performance in both alkaline and acidic media. </LI> <LI> The advantages of Fe@C<SUB>2</SUB>N catalyst over commercial Pt/C are low-cost and comparable ORR activity and superior durability. </LI> <LI> The unusual ORR performance is the result of the electrochemically stable and transparent encapsulating shells. </LI> <LI> Encapsulating shells allow not only an efficient electron tunneling but also protecting unstable active Fe cores. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Oxygen reduction catalyst from iron encapsulated in C<SUB>2</SUB>N framework (Fe@C<SUB>2</SUB>N) exhibits outstanding catalytic activities in both alkaline and acidic media. The Fe@C<SUB>2</SUB>N catalyst holds great potential for commercialization.</P> <P>[DISPLAY OMISSION]</P>

Pharmacological blockade of cholesterol trafficking by cepharanthine in endothelial cells suppresses angiogenesis and tumor growth

Lyu, Junfang,Yang, Eun Ju,Head, Sarah A.,Ai, Nana,Zhang, Baoyuan,Wu, Changjie,Li, Ruo-Jing,Liu, Yifan,Yang, Chen,Dang, Yongjun,Kwon, Ho Jeong,Ge, Wei,Liu, Jun O.,Shim, Joong Sup Elsevier 2017 Cancer letters Vol.409 No.-

<P><B>Abstract</B></P> <P>Cholesterol is an important modulator of membrane protein function and signaling in endothelial cells, thus making it an emerging target for anti-angiogenic agents. In this study, we employed a phenotypic screen that detects intracellular cholesterol distribution in endothelial cells (HUVEC) and identified 13 existing drugs as cholesterol trafficking inhibitors. Cepharanthine, an approved drug for anti-inflammatory and cancer management use, was amongst the candidates, which was selected for in-depth mechanistic studies to link cholesterol trafficking and angiogenesis. Cepharanthine inhibited the endolysosomal trafficking of free-cholesterol and low-density lipoprotein in HUVEC by binding to Niemann-Pick disease, type C1 (NPC1) protein and increasing the lysosomal pH. The blockade of cholesterol trafficking led to a cholesterol-dependent dissociation of mTOR from the lysosomes and inhibition of its downstream signaling. Cepharanthine inhibited angiogenesis in HUVEC and in zebrafish in a cholesterol-dependent manner. Furthermore, cepharanthine suppressed tumor growth in vivo by inhibiting angiogenesis and it enhanced the antitumor activity of the standard chemotherapy cisplatin in lung and breast cancer xenografts in mice. Altogether, these results strongly support the idea that cholesterol trafficking is a viable drug target for anti-angiogenesis and that the inhibitors identified among existing drugs, such as cepharanthine, could be potential anti-angiogenic and antitumor agents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A phenotypic screen identified 13 existing drugs, including cepharanthine, as cholesterol trafficking inhibitors. </LI> <LI> Cepharanthine inhibited lysosomal cholesterol trafficking by binding to NPC1 protein and increasing the lysosomal pH. </LI> <LI> The blockade of cholesterol trafficking led to a cholesterol-dependent dissociation of mTOR from the lysosomes. </LI> <LI> Cepharanthine inhibited angiogenesis in HUVEC and in zebrafish in a cholesterol-dependent manner. </LI> <LI> Cepharanthine treatment enhanced the antitumor activity of cisplatin in lung and breast cancer xenografts in mice. </LI> </UL> </P>

Dispersion of carbon nanotubes in aluminum improves radiation resistance

So, Kang Pyo,Chen, Di,Kushima, Akihiro,Li, Mingda,Kim, Sangtae,Yang, Yang,Wang, Ziqiang,Park, Jong Gil,Lee, Young Hee,Gonzalez, Rafael I.,Kiwi, Miguel,Bringa, Eduardo M.,Shao, Lin,Li, Ju unknown 2016 Nano energy Vol.22 No.-

<P><B>Abstract</B></P> <P>We can mass-produce metal/carbon nanotube (CNT) composites that show improved radiation tolerance. The 0.5wt% Al+CNT composite showed improved tensile strength without reduction of tensile ductility before radiation, and reduced void/pore generation and radiation embrittlement at high displacements per atom (DPA). Under helium ion irradiation up to 72DPA, the 1D carbon nanostructures survive, while sp<SUP>2</SUP> bonded graphene transforms to sp<SUP>3</SUP> tetrahedral amorphous carbon. Self-ion (Al) irradiation converts CNTs to a metastable form of Al<SUB>4</SUB>C<SUB>3</SUB>, but still as slender 1D nanorods with prolific internal interfaces that catalyze recombination of radiation defects, reducing radiation hardening and porosity generation. The 1D fillers may also form percolating paths of “nano-chimneys” that outgas the accumulated helium and other fission gases, providing an essential solution to the gas accumulation problem.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dispersion of CNTs showed improved tensile strength without reduction of ductility. </LI> <LI> CNTs in Al reduced void/pore generation and radiation embrittlement at high DPA. </LI> <LI> Under He ion irradiation, 1D CNTs survive, while sp<SUP>2</SUP> bond transform to sp<SUP>3</SUP> carbon. </LI> <LI> Formation of metastable 1D Al<SUB>4</SUB>C<SUB>3</SUB> from CNTs still recombine radiation defects. </LI> <LI> This nanocomposite can help improve bulk properties for nuclear applications. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effects of reactive oxidants generation and capacitance on photoelectrochemical water disinfection with self-doped titanium dioxide nanotube arrays

Cho, Kangwoo,Lee, Seonggeun,Kim, Hyeonjeong,Kim, Hyung-Eun,Son, Aseom,Kim, Eun-ju,Li, Mengkai,Qiang, Zhimin,Hong, Seok Won Elsevier BV 2019 Applied Catalysis B Vol.257 No.-

<P><B>Abstract</B></P> <P>We herein provide photoelectrochemical (PEC) disinfection activities of anodically prepared TiO<SUB>2</SUB> nanotube (TNT) arrays (diameter ˜ 100 nm, length ˜ 16 μm on average) that were electrochemically self-doped before (bk-TNT) and after (bl-TNT) an atmospheric annealing at 450 °C. The X-ray diffraction indicated predominating anatase TiO<SUB>2</SUB> signal on bl-TNT, while substantial lattice distortion was noticed for bk-TNT. Although the X-ray photoelectron spectra indicated negligible Ti<SUP>3+</SUP> on surface of both TNTs, linear sweep (cyclic) voltammetry and electrochemical impedance spectrometry confirmed the bk-TNT to show greater double layer capacitance and overall photocurrent, coupled with lower charge transfer resistance. Nevertheless, the PEC disinfection of <I>E. coli</I> was significantly invigorated on bl-TNT, while the bactericidal rates in tap water were comparable or even far greater than those in 0.1 M Na<SUB>2</SUB>SO<SUB>4</SUB> solutions, depending on [<I>E. coli</I>]<SUB>0</SUB> (10<SUP>5</SUP> or 10<SUP>7</SUP> CFU/mL). Under a presumed diffusion-controlled kinetic regime in this study, observed effects of capacitance and electrolyte could be interpreted in terms of electrostatic interaction between the electrical double layer of photoanodes and charged bio-solids, such as repulsion by co-ions (SO<SUB>4</SUB> <SUP>2−</SUP>) and adsorption/surface blocking. Analogous PEC experiments on model organic compounds degradation (4-chlorophenol and methylene blue) corroborated a long-term stability of the bl-TNT (up to 30 consecutive cycles) and the role of surface hydroxyl radical as the primary oxidant.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Self-doped anatase (bl-TNT) and amorphous TiO<SUB>2</SUB> nanotube (bk-TNT) were interrogated. </LI> <LI> Lower double layer capacitance of bl-TNT led to higher PEC disinfection of <I>E. coli</I>. </LI> <LI> PEC bactericidal rates in tap water were similar or greater than in Na<SUB>2</SUB>SO<SUB>4</SUB> solution. </LI> <LI> Electrostatic interaction between photoanode and bio-solids determined the kinetics. </LI> <LI> Commercial applicability for point-of-use disinfection was demonstrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrically assisted pressure joining of titanium alloys

Li, Yong-Fang,Das, Hrishikesh,Hong, Sung-Tae,Park, Ju-Won,Han, Heung Nam Elsevier 2018 Journal of manufacturing processes Vol.35 No.-

<P><B>Abstract</B></P> <P>Electrically assisted pressure joining (EAPJ) of a Grade 1 titanium (Ti) alloy is experimentally investigated. In EAPJ, an electric current is directly applied to the specimen during plastic compression. Microstructural analysis shows that solid-state joints are successfully fabricated in the selected Ti alloy without melting. Shear tensile tests shows that the strength and fracture modes of the joint are strongly affected by a combination of the amount of plastic deformation (corresponding to a thickness reduction) and the electric current intensity. An optimal thickness reduction, corresponding to the maximum fracture load, exists for each value of current intensity, and decreases as current intensity increases. A higher fracture load can be obtained by adjusting the combination of the current intensity and the thickness reduction parameters.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ti alloy are solid-state joined by electrically assisted pressure joining (EAPJ). </LI> <LI> The strength and fracture mode of the joint are affected by the EAPJ parameters. </LI> <LI> An optimal thickness reduction exists for each value of current intensity. </LI> <LI> The optimal thickness reduction decreases as the current intensity increases. </LI> </UL> </P>