• Title/Summary/Keyword: Cell Resistance

Search Result 2,492, Processing Time 0.028 seconds

CORRELATIONS BETWEEN HIPPOCAMPAL THETA RHYTHM AND INTRACELLULAR CHARACTERISTICS OF PYRAMIDAL NEURONS (해마 theta 리듬과 pyramidal neuron의 세포내 특성과의 상관관계)

  • Kwon, Oh-Heung;Kim, Young-Jin;Nam, Soon-Hyeun;Kim, Hyeun-Jung;Lee, Man-Gee;Cho, Jin-Hwa;Choi, Byung-Ju
    • Journal of the korean academy of Pediatric Dentistry
    • /
    • v.25 no.4
    • /
    • pp.671-682
    • /
    • 1998
  • Electrophysiological phenomena of pyramidal cells in the CA1 area of the dorsal hippocampus were recorded from and filled with neurobiotin in anesthetized rats. The electropharmacological properties of membrane as well as the cellular-synaptic generation of rhythmic slow activity (theta) were examined. The intracellular response characteristics of these pyramidal cells were distinctly different from responses of interneurons. Pyramidal cells had a high resting membrane potential, a low input resistance, and a large amplitude action potential. A afterhyperpolarization was followed a single action potential. Most of pyramidal cells did not display a spontaneous firing. Pyramidal cells displayed weak inward rectification and anodal break excitation. The slope of the frequency-current relation was 53.4 Hz/nA for the first interspike interval and 15.9 Hz/nA for the last intervals, suggesting the presence of spike frequency adaptation. Neurobiotin-filled neurons showed pyramidal morphology. Cells were generally bipolar dendritc processes ramifying in stratum lacunosum-moleculare, radiatum, and oriens. Commissural stimulation discharged pyramidal cells, followed by excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs). The frequency of theta-related membrane potential oscillation was voltage-independent in pyramidal neurons. At strong depolarization levels (less than 30 mV) pyramidal cells emitted sodium spike oscillation, phase-locked to theta. The observations provide direct evidence that theta-related rhythmic hyperpolarization of principal cells is brought by the rhythmically discharging interneurons. Furthermore, the findings in which interneurons were also paced by rhythmic inhibitory postsynaptic potentials during theta suggest that they were periodically hyperpolarized by their GABAergic septal afferents.

  • PDF

Evaluation of Resistance to Biochemical Corrosion by Simulation Test (시뮬레이션 시험에 의한 생화학적 부식 저항성 평가)

  • Kim, Gyu-Yong;Lee, Eui-Bae
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2008.11a
    • /
    • pp.903-906
    • /
    • 2008
  • To analyze the growth of SOB (Thiobacillus novellus) and biochemical corrosion of concrete, simulation test method and device were developed. And two types of simulation tests were conducted according to a transplant method and a concentration of H2SO4. As a result, the SOB growth in distinct manners and antibiosis of specimen were observed. In the case of the specimens indirectly transplanted with SOB through culture solution submersion at a hydrogen sulfide level of 120ppm, the rapid activation of SOB and the resulting sulfuric acid production were observed. However, SOB were shown to grow rapidly and then die out in a relative short period of time. Meanwhile, in the case of the specimens directly transplanted with SOB at a hydrogen sulfide level of 50ppm, the long-term growth of SOB was possible, but the production of sulfuric acid by SOB did not progress. In the case of the antibiotic metal-mixed specimens, SOB with destroyed cell membranes and internal organizations were observed.

  • PDF

Electrochemical Performance of a Nd2-xSrxNiO4+δ/GDC(x = 0, 0.4, 0.6) as a SOFC Cathode Material (Nd2-xSrxNiO4+δ/GDC(x = 0, 0.4, 0.6) 공기극의 전기화학특성 평가)

  • Lee, Kyoung-Jin;Seo, Jeong-Uk;Lim, Ye-Sol;Hwang, Hae-Jin
    • Journal of the Korean Ceramic Society
    • /
    • v.51 no.1
    • /
    • pp.51-56
    • /
    • 2014
  • Mixed ionic and electronic conducting $K_2NiF_4$-type oxide, $Nd_{2-x}Sr_xNiO_{4+\delta}$ (x = 0, 0.4, 0.6) powders were synthesized by a solid-state reaction technique and solid oxide fuel cells consisting of a $Nd_{2-x}Sr_xNiO_{4+\delta}-GDC$ cathode, a Ni-YSZ anode and 8YSZ as an electrolyte were fabricated. The effect of strontium substitution for neodymium on the electrical and electrochemical properties was examined. The electrical conductivity increased with an increase in the Sr doping content, while it appears that the excess oxygen (${\delta}$) decreased. Sr doping into $Nd_2NiO_{4+\delta}$ resulted in an increase in the cathode polarization resistance and an decrease in the power density of the cell. These phenomena may be associated with the decreased amount of excess oxygen noted in the $Nd_{2-x}Sr_xNiO_{4+\delta}$ cathode.

Effect of Phosphoric Acid on the Electronic and Diffusion Properties of the Anodic Passive Layer Formed on Pb-1.7%Sb Grid of Lead-acid Batteries

  • El-Rahman, H.A. Abd;Salih, S.A.;El-Wahab, A.M. Abd
    • Journal of Electrochemical Science and Technology
    • /
    • v.2 no.2
    • /
    • pp.76-84
    • /
    • 2011
  • Potentiostatic oxidation of Pb-1.7%Sb alloy used in the manufacture of grids of lead-acid batteries over the potential range from -1.0V to 2.3V in 5M $H_2SO_4$ in the absence and the presence of 0.4M $H_3PO_4$ and the self-discharge characteristics of the oxide layer formed is studied by electrochemical impedance spectroscopy (EIS). Depending on the potential value, sharp variations in resistance and capacitance of the alloy are recorded during the oxidation and they can be used for identification of the various substances involved in passive layer. Addition of $H_3PO_4$ is found to deteriorate the insulating properties of the passive layer by the retardation of the formation of $PbSO_4$. $H_3PO_4$ completely inhibits the current and impedance fluctuations recorded in $H_3PO_4$-free solutions in the potential range 0.5 V-1.7 V. These fluctuations are attributed to the occurrence of competitive redox processes that involve the formation of $PbSO_4$, $PbOSO_4$, PbO and $PbO_2$ and the repeated formation and breakdown of the passive layer. Self-discharge experiments indicate that the amount of $PbO_2$ formed in the presence of $H_3PO_4$ is lesser than in the $H_3PO_4$-free solutions. The start of transformation of $PbSO_4$ into $PbO_2$ is greatly shortened. $H_3PO_4$ facilitates the diffusion process of soluble species through the passive layer ($PbSO_4$ and basic $PbSO_4$) but impedes the diffusion process through $PbO_2$.

Development of Boron Doped Carbon Using CO2 Reduction with NaBH4 for Vanadium Redox Flow Battery (수소화 붕소 나트륨 (NaBH4) 과 이산화탄소의 환원을 이용한 바나듐 레독스 흐름전지용 탄소 촉매 개발)

  • Han, Manho;Kim, Hansung
    • Journal of the Korean Electrochemical Society
    • /
    • v.21 no.1
    • /
    • pp.1-5
    • /
    • 2018
  • In this study, boron - doped carbon was prepared by reducing carbon dioxide ($CO_2$) at high temperature by using sodium borohydride ($NaBH_4$). The boron - doped carbon was coated on carbon felt and applied as an electrode for a vanadium redox battery cell. As a result of electrochemical performance evaluation, reversibility of carbon felt coated with boron doped carbon compared to pure carbon felt was improved by about 20% and charge transfer resistance was reduced by 60%. In the charge / discharge results, energy density and energy efficiency were improved by 21% and 12.4%, respectively. These results show that carbon produced by reduction of $CO_2$ can be used as electrode material for redox flow battery.

Characterization of Hemolytic Aeromonas sp. MH-8 Responding to the Exposure of Green Tea Catechin, EGCG (녹차 카테킨 EGCG의 노출에 따른 식중독 세균인 용혈성 Aeromonas sp. MH-8의 특성조사)

  • Kim, Dong-Min;Oh, Kye-Heon
    • KSBB Journal
    • /
    • v.31 no.4
    • /
    • pp.228-236
    • /
    • 2016
  • The aim of this study was to characterize the hemolytic Aeromonas sp. MH-8 exposed to green tea catechin, epigallocatechin gallate (EGCG). Initially, the hemolytic Aeromonas sp. MH-8 was enriched and isolated from stale fish. Bactericidal effects of MH-8 exposed to EGCG ranging from 1 mg/mL to 4 mg/mL were monitored, and complete bactericidal effects were achieved within 3 h at 3 mg/mL and higher concentrations. SDS-PAGE with silver staining revealed that the amount of lipopolysaccharides increased or decreased in the strain MH-8 treated to different concentrations and exposing periods of EGCG in exponentially growing cultures. The stress shock proteins (70-kDa DnaK and 60-kDa GroEL), which might contribute to enhancing the cellular resistance to the cytotoxic effect of EGCG, were induced at different concentrations of EGCG exposed to cell culture of MH-8. Scanning electron microscopic analysis demonstrated the presence of irregular rod shapes with umbilicated surfaces for cells treated with EGCG. 2-DE of soluble protein fractions from MH-8 cultures showed 18 protein spots changed by EGCG exposure. These proteins involved in chaperons (e.g., DnaK, GroEL and trigger factor), enterotoxins (e.g., aerolysin and phospholipase C precursor), LPS synthesis (e.g., LPS biosynthesis protein and outer membrane protein A precursor), and various biosynthesis and energy metabolism were identified by peptide mass fingerprinting using MALDI-TOF. In consequence, EGCG was found to have substantial antibacterial effects against food-poisoning causing bacterium, hemolytic Aeromonas sp. MH-8. Also the results provide clues for understanding the mechanism of EGCG-induced stress and cytotoxicity on Aeromonas sp. MH-8.

Electrochemical Characteristics of Hybrid Capacitor and Pulse Performance of Hybrid Capacitor / Li-ion Battery (Hybrid Capacitor의 전기화학적 특성 및 Hybrid Capacitor / Li-ion Battery의 펄스 방전 특성)

  • Lee, Sun-Young;Kim, Ick-Jun;Moon, Seong-In;Kim, Hyun-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.18 no.12
    • /
    • pp.1133-1138
    • /
    • 2005
  • In this study, we have prepared, as the pluse power source, a commercially supplied Li-ion battery with a capacity of 700 mAh and AC resistivity of 60 md at 1 kHz and nonaqeous asymmetric hybrid capacitor composed of an activated carbon cathode and MCMB anode, and have examined the electrochemical characteristics of hybrid capacitor and the pulse performances of parallel connected hybrid capacitor/Li-ion battery source. The nonaqueous asymmetric hybrid capacitors constituted with each stack number of pairs composed of the cathode, the porous separator and the anode electrode were housed in Al-laminated film cell. The 10 stacked hybrid capacitor, which was charged and discharged at a constant current at 0.25 $mA/cm^2$ between 3 and 4.3 V, has exhibited the capacitance of 108F and the lowest equivalent series resistance was 32 $m{\Omega}$ at 1 kHz. On the other hand, the enhanced run time of Li-ion battery assisted by the hybrid capacitor was obtained with increasing of current density and pulse width in Pulse mode. The best improvement, $84\;\%$ for hybrid capacitor/Li-ion battery was obtained in the condition of a 7C-rate pulse (100 msec)/0.5C-rate standby/$10\;\%$ duty cycle.

Cu Metallization for Giga Level Devices Using Electrodeposition (전해 도금을 이용한 기가급 소자용 구리배선 공정)

  • Kim, Soo-Kil;Kang, Min-Cheol;Koo, Hyo-Chol;Cho, Sung-Ki;Kim, Jae-Jeong;Yeo, Jong-Kee
    • Journal of the Korean Electrochemical Society
    • /
    • v.10 no.2
    • /
    • pp.94-103
    • /
    • 2007
  • The transition of interconnection metal from aluminum alloy to copper has been introduced to meet the requirements of high speed, ultra-large scale integration, and high reliability of the semiconductor device. Since copper, which has low electrical resistivity and high resistance to degradation, has different electrical and material characteristics compared to aluminum alloy, new related materials and processes are needed to successfully fabricate the copper interconnection. In this review, some important factors of multilevel copper damascene process have been surveyed such as diffusion barrier, seed layer, organic additives for bottom-up electro/electroless deposition, chemical mechanical polishing, and capping layer to introduce the related issues and recent research trends on them.

Nutlin-3 downregulates p53 phosphorylation on serine392 and induces apoptosis in hepatocellular carcinoma cells

  • Shi, Xinli;Liu, Jingli;Ren, Laifeng;Mao, Nan;Tan, Fang;Ding, Nana;Yang, Jing;Li, Mingyuan
    • BMB Reports
    • /
    • v.47 no.4
    • /
    • pp.221-226
    • /
    • 2014
  • Drug-resistance and imbalance of apoptotic regulation limit chemotherapy clinical application for the human hepatocellular carcinoma (HCC) treatment. The reactivation of p53 is an attractive therapeutic strategy in cancer with disrupted-p53 function. Nutlin-3, a MDM2 antagonist, has antitumor activity in various cancers. The post-translational modifications of p53 are a hot topic, but there are some controversy ideas about the function of phospho-$Ser^{392}$-p53 protein in cancer cell lines in response to Nutlin-3. Therefore, we investigated the relationship between Nutlin-3 and phospho-$Ser^{392}$-p53 protein expression levels in SMMC-7721 (wild-type TP53) and HuH-7 cells (mutant TP53). We demonstrated that Nutlin-3 induced apoptosis through down-regulation phospho-$Ser^{392}$-p53 in two HCC cells. The result suggests that inhibition of p53 phosphorylation on $Ser^{392}$ presents an alternative for HCC chemotherapy.

The effect of sildenafil on right ventricular remodeling in a rat model of monocrotaline-induced right ventricular failure

  • Bae, Hyun Kyung;Lee, Hyeryon;Kim, Kwan Chang;Hong, Young Mi
    • Clinical and Experimental Pediatrics
    • /
    • v.59 no.6
    • /
    • pp.262-270
    • /
    • 2016
  • Purpose: Pulmonary arterial hypertension (PAH) leads to right ventricular failure (RVF) as well as an increase in pulmonary vascular resistance. Our purpose was to study the effect of sildenafil on right ventricular remodeling in a rat model of monocrotaline (MCT)-induced RVF. Methods: The rats were distributed randomly into 3 groups. The control (C) group, the monocrotaline (M) group (MCT 60 mg/kg) and the sildenafil (S) group (MCT 60 mg/kg+ sildenafil 30 mg/kg/day for 28 days). Masson Trichrome staining was used for heart tissues. Western blot analysis and immunohistochemical staining were performed. Results: The mean right ventricular pressure (RVP) was significantly lower in the S group at weeks 1, 2, and 4. The number of intra-acinar arteries and the medial wall thickness of the pulmonary arterioles significantly lessened in the S group at week 4. The collagen content also decreased in heart tissues in the S group at week 4. Protein expression levels of B-cell lymphoma-2 (Bcl-2)-associated X, caspase-3, Bcl-2, interleukin (IL)-6, matrix metalloproteinase (MMP)-2, endothelial nitric oxide synthase (eNOS), endothelin (ET)-1 and ET receptor A (ERA) in lung tissues greatly decreased in the S group at week 4 according to immunohistochemical staining. According to Western blotting, protein expression levels of troponin I, brain natriuretic peptide, caspase-3, Bcl-2, tumor necrosis factor-${\alpha}$, IL-6, MMP-2, eNOS, ET-1, and ERA in heart tissues greatly diminished in the S group at week 4. Conclusion: Sildenafil alleviated right ventricular hypertrophy and mean RVP. These data suggest that sildenafil improves right ventricular function.