Structure and Performances of xLiFePO4/C·(1 − x)Li3V2(PO4)3/C Cathode for Lithium-Ion Batteries by Using Poly(vinyl alcohol) as Carbon Source

Chang-ling Fan,Wei-hua Zhang,Tao-tao Zeng,Ling-fang Li,Xiang Zhang,Shao-chang Han 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.11

Poly(vinyl alcohol), whose pyrolysis carbon possesses high conductivity of 8.88 × 10−1 S/cm, was used to synthesize xLiFePO4/C·(1 − x)Li3V2(PO4)3/C cathode. It was characterized by X-ray diffraction, scanning electron microscopy, conductivity, cyclic voltammetry, and galvanostatic charge and discharge experiments. Results show that LiFePO4/C and Li3V2(PO4)3/C coexists in the cathode. The particles sizes of 0.75LiFePO4/C·0.25Li3V2(PO4)3/C (x = 0.75) are much smaller than 100 nm due to the role of poly(vinyl alcohol). Its conductivity is 8.79 × 10−2 S/cm. The oxidative and reductive peaks in cyclic voltammetry are sharp and symmetrical. Their low potential gaps indicate that the extractions and insertions of lithium ion possess excellent reversibility. Its discharge capacities at 1 and 5 C are 141.1 and 100.1 mAh/g. The more Li3V2(PO4)3/C in cathode results in the deterioration of electrochemical performances due to its low theoretical capacity. It is concluded that poly(vinyl alcohol) is an effective carbon source in the preparation of xLiFePO4/C·(1 − x)Li3V2(PO4)3/C composite cathode with excellent performances.

Biomechanical analysis of lumbar decompression surgery in relation to degenerative changes in the lumbar spine – Validated finite element analysis

Li, Quan You,Kim, Ho-Joong,Son, Juhyun,Kang, Kyoung-Tak,Chang, Bong-Soon,Lee, Choon-Ki,Seok, Hyun Sik,Yeom, Jin S. Elsevier 2017 Computers in biology and medicine Vol.89 No.-

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>There are no studies about the biomechanical analysis of lumbar decompression surgery in relation to degenerative changes of the lumbar spine. Therefore, the purpose of this study was to compare, by using finite element (FE) analysis, the biomechanical changes of the lumbar spine in terms of annulus stress and nucleus pressure after two different kinds of lumbar decompression surgery in relation to disc degenerative changes.</P> <P><B>Methods</B></P> <P>The validated intact and degenerated FE models (L2-5) were used in this study. In these two models, two different decompression surgical scenarios at L3-4, including conventional laminectomy (ConLa) and the spinous process osteotomy (SpinO), were simulated. Therefore, a total of six models were simulated. Under preloading, 7.5 Nm moments of flexion, extension, lateral bending, and torsion were imposed. In each model, the maximal von Mises stress on the annulus fibrosus and nucleus pressure at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) were analyzed.</P> <P><B>Results</B></P> <P>The ConLa model and disc degeneration model demonstrated a larger annulus stress at the decompression level (L3-4) under all four moments than were seen in the SpinO model and healthy disc model, respectively. Therefore, the ConLa model with moderate disc degeneration showed the highest annulus stress at the decompression level (L3-4). However, the percent change of annulus stress at L3-4 from the intact model to the matched decompression model was less in the moderate disc degeneration model than in the healthy disc model.</P> <P><B>Conclusions</B></P> <P>Although the ConLa model with moderate disc degeneration showed the highest annulus stress, the degenerative models would be less influenced by the decompression technique.</P>

Study on Multi-Field Coupled Evolution Mechanism of Laser Irradiated 40Cr Steel Quenching Process Based on Phase Change Induced Plasticity

Chang Li,Hexin Gao,Xinxue Chen,Zhaotai Liu,Xing Han 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

40Cr is essential to steel for the manufacture of hardened gears, and optimizing its laser quenching process will be of greatsignificance for gear wear and life extension. However, the complete reliance on the experimental trial-and-error approachdoes not effectively reveal the mechanism of the evolution of the laser quenching process in disk laser. Numerical simulationprovides an effective way to obtain the transient evolution of the laser quenching process. In this paper, the temperaturechanges physical parameters of the quenched material are calculated based on the CALPHAD method. Establish a thermoelastic–plastic multi-field coupling model for the laser hardening process of the disk laser 40Cr gear steel. Perform thenumerical calculations on the transient temperature, martensite phase fraction, and the transformation-induced plasticitystress evolution of the 40Cr laser hardening process. Focus on the mechanism of the mutual coupling between phase changebehavior and plastic strain. Calculations show that there is heat accumulation during quenching, with a peak temperatureof 1448 K. Plastic stress has a “hump” distribution, with a peak value of 834 MPa, which is 1.25 mm from the center ofthe focal point. The experimental analyses of the 40Cr gear steel quenching microstructure and hardness distribution stateby the Axioskop2 scanning electron microscope, the KEYENCE VH-Z100R super depth of field 3D microscope, and theQ10M microhardness tester reveal the mechanical behavior of the material and the phase hardening law during the quenchingprocess. That provided an essential theoretical basis for effective prediction on quenching residual stress and optimizingindustrial production parameters.

Synthesis of cross-linked protein-metal hybrid nanoflowers and its application in repeated batch decolorization of synthetic dyes

Patel, Sanjay K.S.,Otari, Sachin V.,Li, Jinglin,Kim, Dong Rip,Kim, Sun Chang,Cho, Byung-Kwan,Kalia, Vipin C.,Kang, Yun Chan,Lee, Jung-Kul Elsevier 2018 Journal of hazardous materials Vol.347 No.-

<P><B>Abstract</B></P> <P>Herein, we report the preparation of a cross-linked protein-metal hybrid nanoflower (NF) system for laccase immobilization. The immobilized laccase showed effective encapsulation yield and activity recovery of 78.1% and 204%, respectively. The catalytic efficiency (<I>k</I> <SUB>cat</SUB> <I>V</I> <SUB>max</SUB> <SUP>−1</SUP>) of cross-linked NF (CL-NF) was 2.2-fold more than that of free laccase. The CL-NF also exhibited significantly higher stability towards pH and temperature changes. It exhibited excellent storage stability and tolerance towards solvents and inhibitors as compared with the free enzyme. After 10 cycles of reuses, the NF and CL-NF laccase showed 41.2% and 92.3% residual activity, respectively. The CL-NF showed high oxidation potential, 265% that of the free enzyme, towards phenolic compounds. The CL-NF laccase retained the residual decolorization efficiency of up to 84.6% for synthetic dyes under repeated batch conditions of 10 cycles. These results suggested that the preparation of CL-NF is an effective approach to enhance the enzymatic properties and has great potential in many industrial applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cross-linked (CL) laccase-metal hybrid nanoflower (NF) was prepared. </LI> <LI> The catalytic efficiency of CL-NF laccase was 2.2-fold higher than that of free laccase. </LI> <LI> CL-NF laccase showed 2.6-fold higher oxidation potential than free laccase towards phenolic compounds. </LI> <LI> Under repeated batch conditions, it retained high decolorization efficiency for synthetic dyes. </LI> </UL> </P>

Research on the Characteristic of Diesel Elastic-plate Impingement Spray

( Chang Yuan Wang ),( Yong Shang ),( Xiang Rong Li ),( Fu Shui Liu ),( Cheng Hui Yu ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

A series of experimental research results on the characteristic of diesel elastic-plate impingement spray using High Speed Photography camera are presented in this paper. The experiments were carried out in a constant volume chamber specially designed, which can hold a high ambiance pressure. The special fixed device was designed so that the elastic-plate can be fixed on the spray path, meanwhile the spray incident angle and height can be changed. The free jet spray and elastic-plate impingement spray was compared under the same experimental condition including different injection pressure and different background pressure. Experimental research showed that impingement spray droplets diffuse more quickly than free jet spray.

One-pot route to synthesize SnO₂-Reduced graphene oxide composites and their enhanced electrochemical performance as anodes in lithium-ion batteries

Li, W.,Yoon, D.,Hwang, J.,Chang, W.,Kim, J. Elsevier Sequoia 2015 Journal of Power Sources Vol.293 No.-

A simple, one-pot route was developed for the synthesis of SnO<SUB>2</SUB>-reduced graphene oxide (RGO) composites. Simultaneous reduction of graphene oxide (GO) and heterogeneous nucleation and growth of SnO<SUB>2</SUB> on the surface of RGO under the supercritical methanol medium resulted in uniform deposition of well-dispersed SnO<SUB>2</SUB> nanoparticles on the RGO sheets. In comparison with the bare SnO<SUB>2</SUB> nanoparticles and bare RGO sheets, the as-synthesized SnO<SUB>2</SUB>-RGO composites exhibited enhanced Li-ion storage and high rate performance. The SnO<SUB>2</SUB>-RGO composite with a SnO<SUB>2</SUB> loading of 58 wt% delivered a reversible discharge capacity of 776 mAh g<SUP>-1</SUP> after 70 cycles at a current density of 0.1 A g<SUP>-1</SUP> and a rate performance of 147 mAh g<SUP>-1</SUP> at a high current density of 5 A g<SUP>-1</SUP>. In addition, after 1000 continuous cycles at 1 A g<SUP>-1</SUP>, the composite electrode exhibited a reversible discharge capacity as high as 531 mAh g<SUP>-1</SUP> with excellent capacity retention. The enhanced long-term cyclability and high-rate performance of the SnO<SUB>2</SUB>-RGO composite can be attributed to the effective confinement of SnO<SUB>2</SUB> nanoparticles on the RGO sheets, and thus, the interparticle agglomeration and volume change associated with alloying-dealloying of SnO<SUB>2</SUB> during cycling can be prevented and cell integrity can be maintained.

중국 의료위생정책 변동과정 분석

이성춘(Li Sheng Chun),이재술(Lee Jae Sul),이민창(Lee Min Chang) 한국지방정부학회 2014 지방정부연구 Vol.18 No.3

본 연구는 역사적 제도주의의 경로진화 모형을 통해 중국 의료위생정책의 진화경로를 확인해 보는 것에 목적이 있다. 분석 결과 의료위생 정책 변동 패턴은 가겹, 가겹, 표류, 전환이 뒤섞인 역동적 과정을 통해 진화해왔다. 의료서비스 공급부족에 따른 문제를 해결하기 위해 각종 조치들이 추가되는 과정과 시장화에 따른 규제개혁의 조치는 가겹으로 해석된다. 이후 합작의료가 와해되고 자비 의료가 증가되는 표류, 공공성 강화를 위한 각종 조치들이 시행되는 전환의 과정을 거친 것이다. 행위자들의 관점에서 정책변동은 단순한 환경 변화만을 뜻하지 않는다. 이들은 전략적 행동변화를 통해 자신들의 이익을 최대화 하고, 이 과정에서 예기치 못한 정책 표류의 현상이 나타날 수 있음을 확인했다. The object of this study is to examine the progress of evolution in Chinese medical and sanitation service policies through the path evolution model of historical institutionalism. The result of the analysis shows that the variation pattern of medical and sanitation service policy has been evolved with dynamic progress including layering, drift and conversion. Both the process of various measures are added in order to solve the problem derived from deficient medical supply and regulatory reform according to marketization could be interpreted as layering. Policy has been gone through the drift which refers to the increase of medical treatment that patients pays by themselves after cooperative medical treatment and conversion that various kinds of measures were executed to enforce the public nature. From the actors' point of view, fluctuation in policy does not mean only the environmental change. They verified that through the strategic change in behavior, they could maximize their benefits, and also drift of policy could occur in this process.

임신시 침구 치료의 고전문헌 고찰

장리 ( Li Chang ),손영주 ( Young Joo Sohn ),이용범 ( Yong Bum Lee ),이향숙 ( Hyang Sook Lee ) 경락경혈학회 2011 Korean Journal of Acupuncture Vol.28 No.2

Objectives: A safety issue on acupuncture and moxibustion treatment during pregnancy is as important as effectiveness. To establish a rationale and research strategy for future studies, a traditional literature review was performed to summarize how and for what conditions acupuncture and moxibustion treatment was given during pregnancy. Methods: An extensive traditional literature search for acupuncture and moxibustion treatment during pregnancy was conducted in texts on acupuncture and moxibustion, obstetrics and gynecology, and comprehensive medical texts. Treatment conditions, methods, and contraindications were summarized and tabulated. Results: Twenty-eight books were included in our review. Most frequent description of acupuncture and moxibustion treatment use during pregnancy was for difficult delivery including breech presentations; commonly used acupuncture points for difficult labor included LI4, SP6, BL67, BL60, KI6, ST30, SP12, LR4, LR3, PC6, CV3, CV14, KI13, and GB21, indicating that they may have to be avoided during pregnancy. Descriptions of other symptoms or conditions were sparse. For habitual abortion or recurrent miscarriage, moxibustion on GV4, BL23, CV3, KI8, and KI2 was indicated. A combination of LI4 and SP6, and CV4 were contraindicated during pregnancy consistently across the reviewed books. Conclusions: Our traditional literature review has shown that the use of acupuncture and moxibustion treatment during pregnancy has been limited. Given that more and more pregnant women are interested in safe and effective treatment, further research of acupuncture`s safety and efficacy during pregnancy is urgently needed.

Effects of aerosol on evaporation, freezing and precipitation in a multiple cloud system

Lee, Seoung Soo,Kim, Byung-Gon,Yum, Seong Soo,Seo, Kyong-Hwan,Jung, Chang-Hoon,Um, Jun Shik,Li, Zhanqing,Hong, JinKyu,Chang, Ki-Ho,Jeong, Jin-Yim Springer-Verlag 2017 Climate dynamics Vol.48 No.3

<P>Aerosol effects on clouds and precipitation account for a large portion of uncertainties in the prediction of the future course of global hydrologic circulations and climate. As a process of a better understanding of interactions between aerosol, clouds and precipitation, simulations are performed for a mixed-phase convective multiple-cloud system over the tropics. Studies on single-cloud systems have shown that aerosol-induced increases in freezing, associated increases in parcel buoyancy and thus the intensity of clouds (or updrafts) are a main mechanism which controls aerosol-cloud-precipitation interactions in convective clouds. However, in the multiple-cloud system that plays much more important roles in global hydrologic circulations and thus climate than single-cloud systems, aerosol effects on condensation play the most important role in aerosol-induced changes in the intensity of clouds and the effects on freezing play a negligible role in those changes. Aerosol-induced enhancement in evaporation intensifies gust fronts and increases the number of subsequently developing clouds, which leads to the substantial increases in condensation and associated intensity of convection. Although aerosol-induced enhancement in freezing takes part in the increases in condensation by inducing stronger convergence around cloud bottom, the increases in condensation are similar to one order of magnitude larger than those in freezing. It is found that while aerosol-induced increases in freezing create intermittent extremely heavy precipitation, aerosol-induced increases in evaporation enhance light and medium precipitation in the multiple-cloud system here. This increase in light and medium precipitation makes it possible that cumulative precipitation increases with increasing aerosol concentration, although the increase is small. It is interesting that the altitude of the maximum of the time- and domain-averaged hydrometeor mass densities is quite robust to increases in aerosol concentration. This is because locations of gust fronts and homogeneous freezing do not vary significantly with changing aerosol concentration and this outweighs aerosol effects on hydrometeor size.</P>

동결 보존에 의한 돼지 정자 세포질 칼슘 신호의 변화

이선우,이옥화,김준철,명평근,박창식,우선희 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

Although mammalian sperms are cryopreserved for in vitro fertilization a process of cryopreservation decreases the fertility. Acrosome reaction requires depolarization-induced ca^(2+) influx and ca^(2+) releases from the ca^(2+) stores. To examine whether the cellular ca^(2+) mobilization is altered by a sperm cryopreservation we compared cytosolic ca^(2+) signals between fresh and cryopreserved pig sperms using confocal ca^(2+) imaging. The magnitudes of depolarization-induced ca^(2+) increases were significantly smaller in cryopreserved sperms. Exposures to 10 mM caffeine or 5 μM thapsigargin elicited less ca^(2+) increases in the cryopreserved sperms compared to fresh sperms. In addition, progesterone-triggered ca^(2+) rises, that are thought to enhance acrosome reaction, were completely abolished in the cryopreserved sperms. These results suggest that storage and(/or) release of ca^(2+) from the intracellular ca^(2+) stores in pig sperms are significantly impaired by the process of cryopreservation.