• Title/Summary/Keyword: C-signal

Search Result 4,123, Processing Time 0.034 seconds

Whitening activity of Ficus carica L. fruits extract through inhibition of tyrosinase and MITF expression (무화과(Ficus carica L.) 열매 추출물의 tyrosinase 및 MITF 발현 억제를 통한 미백 활성)

  • Min Ji Kim;Si Eun Park;Geun soo Lee;Jin Hwa Kim;Sunwoo Kwon;Hyung Seo Hwang
    • Journal of Applied Biological Chemistry
    • /
    • v.66
    • /
    • pp.204-212
    • /
    • 2023
  • Whitening is inhibitory activity of the melanin synthesis of melanocytes. Recently, whitening materials have been developed on natural materials because of its side effects on skin. Figs (Ficus Carica L.) is a fruit belonging to the Moraceae family and whitening activity was reported in focusing on the fig's stem and leaf components, but whitening activity of the figs fruit was not known. Thus, in this study, we tried to observe its anti-melanogenesis as well as antioxidant and anti-inflammation. The radical scavenging activity of figs fruits extract (FFE) was observed as the level of 34.52±1.98%/60.71±1.26% compared to the control in the its maximum concentration in the DPPH/ABTS assay. Cytotoxicity of FFE was observed at 10% concentration by CCK8 assay, so the maximum concentration was set at 5% and applied to all experiments. FFE concentration dependently decreased NO production associated with inducible nitric oxide synthase, cyclooxygenase-2, interleukin-6 and tumor necrosis factor-α gene expression, these strongly suggesting anti-inflammatory activity. In melanin contents assay, FFE significantly down-regulated melanin production in α-MSH-stimulated B16F10 cell as well as tyrosinase inhibition in vitro. In addition, FFE decreased the Microphthalmia-associated transcription factor (MITF) mRNA expression about 94.34% compared to the α-MSH treatment group in RT-PCR. Finally, FFE significantly reduced the MITF, cAMP response element-binding protein and tyrosinase protein expression in the α-MSH stimulated B16F10 cell. Through these results, we found that FFE can not only directly inhibit tyrosinase enzyme activity but also suppress melanogenesis through regulation of MITF gene expression in α-MSH signal transduction.

The Comparative Imaging Study on Mn-phthalocyanine and Mangafodipir trisodium in Experimental VX2 Animal Model (실험적으로 유발시킨 VX2 동물모델에서의 Mn-phthalocyanine과 Mangafodipir trisodium의 비교영상)

  • Park Hyun-Jeong;Ko Sung-Min;Kim Yong-Sun;Chang Yongmin
    • Investigative Magnetic Resonance Imaging
    • /
    • v.8 no.1
    • /
    • pp.32-41
    • /
    • 2004
  • Purpose : To measure the NMR relaxation properties of MnPC, to observe the characteristics of liver enhancement patterns on MR images in experimentally implanted rabbit VX2 tumor model, and to estimate the possibility of tissue specific contrast agent for MnPC in comparison with the hepatobiliary agent. Materials and Methods : Phthalocyanine (PC) was chelated with paramagnetic ions, manganese (Mn). 2.01 g (5.2 mmol) of phthalocyanine was mixed with 0.37 g (1.4 nlmol) of Mn chloride at $310^{\circ}C$ for 36 hours and then purified by chromatography ($CHCl_3:\;CH_3OH=98:2$, volume ratio) to obtain 1.04 g $(46\%)$ of MnPC (molecular weight = 2000 daltons). The T1/T2 relaxivity (R1/R2) for MnPC were determined at a 1.5 T (64 MHz) MR spectrometer. VX2 tumor model was experimentally implanted in the liver parenchyma of rabbits. All MR studies were performed on 1.5 T. The human extremity radio frequency coil of a bird cage type was employed. MR images were acquired at 17 to 24 days after VX2 carcinoma implantation.4 mmol/kg MnPC and 0.01 mmol/kg Mn-DPDP were injected via the ear vein of rabbits. T1-weighted images were obtained with spin-echo (TR/TE=516/14 msec) and fast multiplanar spoiled gradient recalled (TR/TE : 80/4 msec, $60^{\circ}$ flip angle) pulse sequence. Fast spin-echo (TR/TE=1200/85 msec) was used to obtain the T2-weighted images. Results : The value of T1/T2 relaxivity (R1/R2) of MnPC was $7.28\;mM^{-1}S^{-1}$ and $55.56\;mM^{-1}S^{-1}$ respectively at 1.5 T (64 MHz). Because the T2 relaxivity of MnPC that bonded strongly, covalently manganese with phthalocyanine was very high, the signal intensity of liver parenchyma was decreased on postcontrast T2-weighted images and we could easily distinguish the VX2 carcinoma within the liver parenchyma. When MnPC was administrated intravenously, the tumor margin delineation was more remarkable than Mn-DPDP-enhanced images. The enhancement of liver parenchyma with MnPC persisted at relatively high levels over at least one hour after injection of the contrast agents. Conclusion : The hepatic uptake and biliary excretion of MnPC, which are similar to Mn-DPDP, suggest that this agent is a new liver-specific agent. Also, MnPC seems to be used as a dual contrast agent (T1 and T2) with high T2 relaxivity. However, it is warranted that MnPC needs further investigation as a potential contrast agent for MR imaging of the liver. That is, further characterizations of MnPC are needed in vivo and in vitro before clinical trials. The diagnostic potential of MnPC will also have to be examined more in the animal models of additional types.

  • PDF

Anti-inflammatory effect of Sinhyowoldo-san Extract with regard to Pro-inflammatory Mediators in PMA plus A23187-induced Human Mast Cells (인간 비만세포에서 PMA와 A23187에 의해 유도된 전염증 매개체에 대한 신효월도산 추출물의 항염증 효과)

  • Wi, Gyeong;Yang, Da-Wun;Kang, Ok-Hwa;Kim, Sung-Bae;Mun, Su-Hyun;Seo, Yun-Soo;Kang, Da-Hye;Lim, Jae-Soo;Kim, Ma-Ryong;Kwak, Nam-Won;Kong, Ryong;Kwon, Dong-Yeul
    • The Korea Journal of Herbology
    • /
    • v.29 no.6
    • /
    • pp.117-123
    • /
    • 2014
  • Objectives : Sinhyowoldo-san (SHWDS) is said to be a traditional medicine used for shigellosis, abdominal pain, diarrhea. But mechanism of SHWDS mediated-modulation of immune function is not sufficiently understood. To ascertain the molecular mechanisms of SHWDS 70% EtOH extract on pharmacological and biochemical actions in inflammation, we researched the effect of pro-inflammatory mediators in phorbol-12-myristate-13-acetate (PMA)+ A23187-activated human mast cell line (HMC-1). Methods : In the present research, cell viability was measured by MTS assay. pro-inflammatory cytokine production was measured by performing enzyme-linked immunosorbent assay (ELISA), reverse transcription polymerase chain reaction (RT-PCR), and western blot analysis to analyze the activation of mitogen-activated protein kinases (MAPKs), nuclear factor kappa-light-chain-enhancer of activated B cells ($NF-{\kappa}B$). The investigation focused on whether SHWDS inhibited the expressions of interleukin-6 (IL-6), interleukin-8 (IL-8), MAPKs and $NF-{\kappa}B$ in PMA+A23187-activated HMC-1 cells. Results : SHWDS has no cytotoxicity at measured concentration (50, 100, and $250{\mu}g/ml$). SHWDS ($250{\mu}g/ml$) inhibits pro-inflammatory cytokine expression in PMA+ A23187-activated HMC-1 cells. Moreover, SHWDS inhibited cyclooxygenase (COX)-2 expression. In activated HMC-1 cells, SHWDS suppressed phosphorylation of extracellular signal-regulated kinase (ERK 1/2) and c-jun N-terminal Kinase (JNK 1/2). Then, SHWDS suppressed activation of nuclear factor $NF-{\kappa}B$ in nuclear, degradation of IkB ${\alpha}$ in cytoplasm. Conclusions : We propose that SHWDS has an anti-inflammatory therapeutic potential, which may result from inhibition of ERK 1/2, JNK 1/2 phosphorylation and $NF-{\kappa}B$ activation, thereby decreasing the expression of pro-inflammatory genes.

GPU Based Feature Profile Simulation for Deep Contact Hole Etching in Fluorocarbon Plasma

  • Im, Yeon-Ho;Chang, Won-Seok;Choi, Kwang-Sung;Yu, Dong-Hun;Cho, Deog-Gyun;Yook, Yeong-Geun;Chun, Poo-Reum;Lee, Se-A;Kim, Jin-Tae;Kwon, Deuk-Chul;Yoon, Jung-Sik;Kim3, Dae-Woong;You, Shin-Jae
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2012.08a
    • /
    • pp.80-81
    • /
    • 2012
  • Recently, one of the critical issues in the etching processes of the nanoscale devices is to achieve ultra-high aspect ratio contact (UHARC) profile without anomalous behaviors such as sidewall bowing, and twisting profile. To achieve this goal, the fluorocarbon plasmas with major advantage of the sidewall passivation have been used commonly with numerous additives to obtain the ideal etch profiles. However, they still suffer from formidable challenges such as tight limits of sidewall bowing and controlling the randomly distorted features in nanoscale etching profile. Furthermore, the absence of the available plasma simulation tools has made it difficult to develop revolutionary technologies to overcome these process limitations, including novel plasma chemistries, and plasma sources. As an effort to address these issues, we performed a fluorocarbon surface kinetic modeling based on the experimental plasma diagnostic data for silicon dioxide etching process under inductively coupled C4F6/Ar/O2 plasmas. For this work, the SiO2 etch rates were investigated with bulk plasma diagnostics tools such as Langmuir probe, cutoff probe and Quadruple Mass Spectrometer (QMS). The surface chemistries of the etched samples were measured by X-ray Photoelectron Spectrometer. To measure plasma parameters, the self-cleaned RF Langmuir probe was used for polymer deposition environment on the probe tip and double-checked by the cutoff probe which was known to be a precise plasma diagnostic tool for the electron density measurement. In addition, neutral and ion fluxes from bulk plasma were monitored with appearance methods using QMS signal. Based on these experimental data, we proposed a phenomenological, and realistic two-layer surface reaction model of SiO2 etch process under the overlying polymer passivation layer, considering material balance of deposition and etching through steady-state fluorocarbon layer. The predicted surface reaction modeling results showed good agreement with the experimental data. With the above studies of plasma surface reaction, we have developed a 3D topography simulator using the multi-layer level set algorithm and new memory saving technique, which is suitable in 3D UHARC etch simulation. Ballistic transports of neutral and ion species inside feature profile was considered by deterministic and Monte Carlo methods, respectively. In case of ultra-high aspect ratio contact hole etching, it is already well-known that the huge computational burden is required for realistic consideration of these ballistic transports. To address this issue, the related computational codes were efficiently parallelized for GPU (Graphic Processing Unit) computing, so that the total computation time could be improved more than few hundred times compared to the serial version. Finally, the 3D topography simulator was integrated with ballistic transport module and etch reaction model. Realistic etch-profile simulations with consideration of the sidewall polymer passivation layer were demonstrated.

  • PDF

What are the Possible Roles of CO2 on Stomatal Mechanism? (기공 메커니즘에 대한 CO2의 역할은 무엇인가?)

  • Lee, Joon Sang
    • Korean Journal of Environment and Ecology
    • /
    • v.30 no.1
    • /
    • pp.130-134
    • /
    • 2016
  • How does $CO_2$ affect on the stomatal mechanism? The mechanism of stomatal opening by $CO_2$ is not clear as it is difficult to see $CO_2$ effect on light-induced stomatal opening. Furthermore, stomata may react differently according to the concentration of $CO_2$. The significance of the possible endogenous rhythms must consider to understand on $CO_2$-related response. It is clear that $CO_2$ has an effect on the accumulation of osmotic materials which determines the degree of stomatal apertures because it is known that stomata open in the condition of the reduced $CO_2$ concentration. However, it is not fully understood how $CO_2$ leads to the stomatal opening. It has been thought that $CO_2$ can not affect on the ion fluxes which determines the increase of osmotic potential in guard cells. However, in this study, the changes of guard cell membrane permeability by $CO_2$ have been focused on. There are many reports that $CO_2$ related reactions are dominant when the leaf is exposed to certain a mount of $CO_2$. The hypothesis of the stomatal opening by light is based on the increase of osmotic materials in guard cells including $K^+$, $Cl^-$, sucrose and $malate^{2-}$. It was reported that $CO_2$ induced a big hyperpolarization indicating that $H^+$ was extruded to the cell outside. It was also found that $CO_2$ caused guard cell membrane hyperpolarization in the intact leaf up to 3 or 4 times higher than that of light induced membrane hyperpolarization. These results represent that $CO_2$ can affect on the change of physical characteristics which affects on the change of the membrane permeability.

Anti-inflammatory Activities Verification of Ambrosia trifida L. extract in RAW 264.7 Cells (RAW 264.7 세포에서의 단풍잎돼지풀 추출물의 항염증 활성 검증)

  • Yoo, Dan-Hee;Lee, Jin-Young
    • Microbiology and Biotechnology Letters
    • /
    • v.48 no.1
    • /
    • pp.79-89
    • /
    • 2020
  • This study was performed to evaluate the anti-inflammatory activities of 70% ethanol extract from Ambrosia trifida L. (AT). The electron donating ability and ABTS+ radical scavenging ability of extract from AT was shown to be 84.1% and 92.5% at 1,000 ㎍/ml concentration. The astringent effect of extract from AT was shown to be 94.7% at 1,000 ㎍/ml. The anti- inflammatory activities of extract of AT were investigated using RAW 264.7 cells induced by lipopolysaccharide (LPS). The cell toxicity effect of AT extract on RAW 264.7 performed MTT assay. As a result of the measured cell toxicity effect, 90% or more was shown with cell viability at a 500 ㎍/ml concentration. In nitric oxide synthesis inhibition effect, it was shown that extract from AT concentration dependent inhibited nitric oxide production. The protein expression inhibitory effect of AT extract was measured by western blot at 25, 50, and 100 ㎍/ml concentration and the β-actin used as a positive control. Consequently, the inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 protein expression inhibitory effect was decreased by 8.6%, 25.1% at 100 ㎍/ml concentration. The phosphorylation of extracellular signal-regulated kinase 1/2, p38, c-Jun NH2-terminal kinase and Iκ-Bα protein expression inhibitory effect was a decreased dependent concentration. The mRNA expression inhibitory effect was measured by reverse transcription - polymerase chain reaction at 25, 50, and 100 ㎍/ml concentration and the glyceraldehyde-3-phosphate dehydrogenase used as a positive control. Consequently, the iNOS, COX-2, interleukin (IL)-1β, IL-6 and tumor necrosis factor-α mRNA expression inhibition effect was a decreased dependent concentration in an LPS-activated macrophage. In conclusion, AT extract may have some effects on inflammatory factors as potential anti-inflammatory agents and natural substance for cosmetics.

Biodistribution of Iodine-131-Iodomisonidazole and Imaging of Tumor Hypoxia in Mice bearing CT-26 Adenocarcinoma (CT-26 선암을 접종한 마우스에서 Iodine-131-Iodomisonidazole의 생체분포 및 종양저산소증의 영상화)

  • Kim, Hye-Won;Kim, Chang-Guhn;Yoon, Kwon-Ha;Kim, Hyun-Jeong;Juhng Seon-Kwan;Roh, Byung-Suk;Yang, David J.;Kim, E.Edmund;Lee, Hyun-Chul
    • The Korean Journal of Nuclear Medicine
    • /
    • v.33 no.3
    • /
    • pp.289-297
    • /
    • 1999
  • Purpose: Misonidazole is a radiosensitizer that binds in hypoxic cells. The purpose of this study was to find out the feasibility of I-131-Iodomisonidazole (IMISO) for imaging of tumor hypoxia. Materials and Methods: Tosyl precursor was dissolved in acetonitrile and I-131-NaI was added to synthesize IMISO. Balb/c mice inoculated with CT-26 adenocarcinoma were injected with IMISO. Mice were sacrificed at 1, 2, 4, 24 hr and % of injected dose per gram of tissue (%ID/g) was determined. For scintigraphy and MRI, mouse bearing CT-26 adenocarcinoma was administered with IMISO and imaging was performed 4 hr after. Then, mouse body was fixed and microtomized slice was placed on radiographic film for autoradiography Results: %ID/g of tumor was 1.64 (1h), 0.98 (2h), 0.85 (4h) and 0.20 (24h), respectively. At 24h, %ID/g of tumor was higher than that of all other tissues except thyroid. Tumor to muscle ratio increased with time and tumor to blood ratio also increased with time and reached 1.53 at 24 hr. On autoradiogram, tumor was well visualized as an increased activity in central hypoxic area of the tumor which corresponds to the area of high signal intensity on T2-weighted MR image. On scintigraphy, tumor uptake was visualized. Conclusion: This results suggest that IMISO may have a potential for tumor hypoxia imaging in mouse model. However, further study is needed to improve it's localization in tumor tissue and to achieve acceptable images of tumor hypoxia.

  • PDF

Empirical Orthogonal Function Analysis of Surface Pressure, Sea Surface Temperature and Winds over the East Sea of the Korea (Japan Sea) (한국 동해에서의 해면기압, 해수면온도와 해상풍의 경험적 직교함수 분석)

  • NA Jung-Yul;HAN Snag-Kyu;SEO Jang-Won;NOH Yi-Gn;KANG In-Sik
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.30 no.2
    • /
    • pp.188-202
    • /
    • 1997
  • The seasonal variability of the sea surface winds over the last Sea of Korea (Japan Sea) is investigated by means of empirical orthogonal function (EOF) analysis. The combined representation of fields of three climatic variables by empirical orthogonal functions is discussed. The eigenvectors are derived from daily sea level pressure, wind speed and 10-day mean sea surface temperature (SST) during 15 years $(1978\~1992)$. The spatial patterns of the mean pressure are characterized by the high pressure in the western part and the low pressure in the eastern part. The spatial distribution of the standard deviation (SD) of pressure are characterized by max SD of 6.6 mb near the Vladivostok, and minima along the coast of the Japan. In Vladivostok, the maxima of SD of SST and south-north wind (WV) were also occurred. The representation of fields of individual meteorological variables by EOF shows that the first mode of the west-east wind (WU) explain over $47.3\%$ of the variance and the second mode of WU represents $30\%$. Especially, the first mode of the WV explain $70.9\%$ of the variance and their time series coefficients show 1-cpy, 0.5-cpy frequency spectrum. The spatial distribution of the first mode eigenvectors of SST are characterized by maximum near Vladivostok. The combined representation of fields of several variables (pressure, wind, SST) reveals that the first mode magnitudes of the variance of the combined eigenvectors (WU-PR) are increased. By means of this result, the 1-year peak and the 6-months peak are remarkable. In the three combined patterns (wind, pressure, SST), the second mode of the eigenvector (wind) is affected by the SST. Their time coefficients of the first mode show noticeable 1-year peak. The spectral analysis of the second mode shows broad seasonal signal with the period of 4-months and a significant peak of variability at 3-month period.

  • PDF

Immunomodulatory effect of the water extract of Aster tataricus through mitogen-activated protein kinase signaling pathway (Aster tataricus 물 추출물의 mitogen-activated protein kinase 신호 전달 경로를 통한 면역 조절 효과)

  • Lee, Chea Yeon;Park, Hyo Sung;Kong, Deok-Hoon;Kim, Young Kwan;Cho, Whajung
    • Journal of Nutrition and Health
    • /
    • v.53 no.5
    • /
    • pp.452-463
    • /
    • 2020
  • Purpose: Aster tataricus (AT) is one of the Asteraceae perennial herbs used in traditional Chinese medicine. The herb contains various bioactive substances, such as flavonoids, isoflavonoids, and phenolic compounds in the roots, and exhibits a range of effects including anti-bacterial, anti-oxidant, and anti-inflammatory activities. This study compared the immunomodulatory effects of ethanol and water extracts of whole AT, except the roots, and analyzed the molecular mechanisms for the regulatory effects on cytokine secretion from THP-1 cells. Methods: The effects of AT extract on the cell viability and proliferation of THP-1 cells were analyzed using the Cell Counting Kit-8 method. The concentrations of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the cell culture supernatant of the AT-treated THP-1 cells were measured using an enzyme-linked immunosorbent assay. The protein levels of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), inhibitor of nuclear factor kappa B (IκBα), and mitogen-activated protein kinase (MAPK) phosphorylation in the cell lysates were determined by western blotting. Results: The water extract and the ethanol extract of AT did not affect the cell viability, and increased the proliferation of THP-1 cells significantly compared to the vehicle. The water extract increased the secretion of IL-1β from THP-1 cells in a dose-dependent manner, but the ethanol extract had no effect. The expression of COX-2 and iNOS protein and the phosphorylation of MAPK and Akt were induced in AT-treated cells. In addition, IκBα was degraded by AT in a concentration-dependent manner. IL-1β secretion by AT was reduced by extracellular-signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) inhibitors, while TNF-α secretion was decreased by inhibitors of ERK, p38 MAPK, and JNK. Interestingly, the p38 MAPK inhibitor increased the production of IL-1β by AT further. Conclusion: The water extract of the above-ground parts of AT contains immunomodulatory bioactive substances that stimulate immune cells through the MAPK signaling pathway.

Structural Behavior of Mixed $LiMn_2O_4-LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ Cathode in Li-ion Cells during Electrochemical Cycling

  • Yun, Won-Seop;Lee, Sang-U
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • 2011.05a
    • /
    • pp.5-5
    • /
    • 2011
  • The research and development of hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV) and electric vehicle (EV) are intensified due to the energy crisis and environmental concerns. In order to meet the challenging requirements of powering HEV, PHEV and EV, the current lithium battery technology needs to be significantly improved in terms of the cost, safety, power and energy density, as well as the calendar and cycle life. One new technology being developed is the utilization of composite cathode by mixing two different types of insertion compounds [e.g., spinel $LiMn_2O_4$ and layered $LiMO_2$ (M=Ni, Co, and Mn)]. Recently, some studies on mixing two different types of cathode materials to make a composite cathode have been reported, which were aimed at reducing cost and improving self-discharge. Numata et al. reported that when stored in a sealed can together with electrolyte at $80^{\circ}C$ for 10 days, the concentrations of both HF and $Mn^{2+}$ were lower in the can containing $LiMn_2O_4$ blended with $LiNi_{0.8}Co_{0.2}O_2$ than that containing $LiMn_2O_4$ only. That reports clearly showed that this blending technique can prevent the decline in capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and related structural phase transitions for these composite cathodes. In this presentation, we will report our in situ x-ray diffraction studies on this mixed composite cathode material during charge-discharge cycling. The mixed cathodes were incorporated into in situ XRD cells with a Li foil anode, a Celgard separator, and a 1M $LiPF_6$ electrolyte in a 1 : 1 EC : DMC solvent (LP 30 from EM Industries, Inc.). For in situ XRD cell, Mylar windows were used as has been described in detail elsewhere. All of these in situ XRD spectra were collected on beam line X18A at National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory using two different detectors. One is a conventional scintillation detector with data collection at 0.02 degree in two theta angle for each step. The other is a wide angle position sensitive detector (PSD). The wavelengths used were 1.1950 ${\AA}$ for the scintillation detector and 0.9999 A for the PSD. The newly installed PSD at beam line X18A of NSLS can collect XRD patterns as short as a few minutes covering $90^{\circ}$ of two theta angles simultaneously with good signal to noise ratio. It significantly reduced the data collection time for each scan, giving us a great advantage in studying the phase transition in real time. The two theta angles of all the XRD spectra presented in this paper have been recalculated and converted to corresponding angles for ${\lambda}=1.54\;{\AA}$, which is the wavelength of conventional x-ray tube source with Cu-$k{\alpha}$ radiation, for easy comparison with data in other literatures. The structural changes of the composite cathode made by mixing spinel $LiMn_2O_4$ and layered $Li-Ni_{1/3}Co_{1/3}Mn_{1/3}O_2$ in 1 : 1 wt% in both Li-half and Li-ion cells during charge/discharge are studied by in situ XRD. During the first charge up to ~5.2 V vs. $Li/Li^+$, the in situ XRD spectra for the composite cathode in the Li-half cell track the structural changes of each component. At the early stage of charge, the lithium extraction takes place in the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component only. When the cell voltage reaches at ~4.0 V vs. $Li/Li^+$, lithium extraction from the spinel $LiMn_2O_4$ component starts and becomes the major contributor for the cell capacity due to the higher rate capability of $LiMn_2O_4$. When the voltage passed 4.3 V, the major structural changes are from the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, while the $LiMn_2O_4$ component is almost unchanged. In the Li-ion cell using a MCMB anode and a composite cathode cycled between 2.5 V and 4.2 V, the structural changes are dominated by the spinel $LiMn_2O_4$ component, with much less changes in the layered $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, comparing with the Li-half cell results. These results give us valuable information about the structural changes relating to the contributions of each individual component to the cell capacity at certain charge/discharge state, which are helpful in designing and optimizing the composite cathode using spinel- and layered-type materials for Li-ion battery research. More detailed discussion will be presented at the meeting.

  • PDF