• Title/Summary/Keyword: Energy loss reduction

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Tailoring the properties of spray deposited V2O5 thin films using swift heavy ion beam irradiation

  • Rathika, R.;Kovendhan, M.;Joseph, D. Paul;Pachaiappan, Rekha;Kumar, A. Sendil;Vijayarangamuthu, K.;Venkateswaran, C.;Asokan, K.;Jeyakumar, S. Johnson
    • Nuclear Engineering and Technology
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    • v.52 no.11
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    • pp.2585-2593
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    • 2020
  • Swift heavy ion (SHI) beam irradiation can generate desirable defects in materials by transferring sufficient energy to the lattice that favours huge possibilities in tailoring of materials. The effect of Ag15+ ion irradiation with energy 200 MeV on spray deposited V2O5 thin films of thickness 253 nm is studied at various ion doses from 5 × 1011 to 1 × 1013 ions/㎠. The XRD results of pristine film confirmed orthorhombic structure of V2O5 and its average crystallite size was found to be 20 nm. The peak at 394 cm-1 in Raman spectra confirmed O-V-O bonding of V2O5, whereas 917 cm-1 arise because of distortion in stoichiometry by a loss of oxygen atoms. Raman peaks vanished completely above the ion fluence of 5 × 1012 ions/㎠. Optical studies by UV-Vis spectroscopy shows decrement in transmittance with an increase in ion fluence up to 5 × 1012 ions/㎠. The red shift is observed both in the direct and indirect band gaps until 5 × 1012 ions/㎠. The surface topography of the pristine film revealed sheath like structure with randomly distributed spherical nano-particles. The roughness of film decreased and the density of spherical nanoparticles increased upon irradiation. Irradiation improved the conductivity significantly for fluence 5 × 1011 ions/㎠ due to band gap reduction and grain growth.

Enhanced Production of Adenosine Triphosphate by Pharmacological Activation of Adenosine Monophosphate-Activated Protein Kinase Ameliorates Acetaminophen-Induced Liver Injury

  • Hwang, Jung Hwan;Kim, Yong-Hoon;Noh, Jung-Ran;Choi, Dong-Hee;Kim, Kyoung-Shim;Lee, Chul-Ho
    • Molecules and Cells
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    • v.38 no.10
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    • pp.843-850
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    • 2015
  • The1hepatic cell death induced by acetaminophen (APAP) is closely related to cellular adenosine triphosphate (ATP) depletion, which is mainly caused by mitochondrial dysfunction. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a key sensor of low energy status. AMPK regulates metabolic homeostasis by stimulating catabolic metabolism and suppressing anabolic pathways to increase cellular energy levels. We found that the decrease in active phosphorylation of AMPK in response to APAP correlates with decreased ATP levels, in vivo. Therefore, we hypothesized that the enhanced production of ATP via AMPK stimulation can lead to amelioration of APAP-induced liver failure. A769662, an allosteric activator of AMPK, produced a strong synergistic effect on AMPK Thr172 phosphorylation with APAP in primary hepatocytes and liver tissue. Interestingly, activation of AMPK by A769662 ameliorated the APAP-induced hepatotoxicity in C57BL/6N mice treated with APAP at a dose of 400 mg/kg intraperitoneally. However, mice treated with APAP alone developed massive centrilobular necrosis, and APAP increased their serum alanine aminotransferase and aspartate aminotransferase levels. Furthermore, A769662 administration prevented the loss of intracellular ATP without interfering with the APAP-mediated reduction of mitochondrial dysfunction. In contrast, inhibition of glycolysis by 2-deoxy-glucose eliminated the beneficial effects of A769662 on APAP-mediated liver injury. In conclusion, A769662 can effectively protect mice against APAP-induced liver injury through ATP synthesis by anaerobic glycolysis. Furthermore, stimulation of AMPK may have potential therapeutic application for APAP overdose.

A Preliminary Study on Polyester Aluminum Bag as the Possible Substitute for Tedlar Bag Sampler in RSC Analysis (테들러 백 샘플러의 대체 소재로서 폴리에스터 알루미늄 백에 대한 예비연구: 환원황화합물을 중심으로)

  • Kim, Ki-Hyun;Jo, Sang-Hee
    • Journal of Korean Society for Atmospheric Environment
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    • v.27 no.4
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    • pp.454-459
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    • 2011
  • In this study, the recovery rate of Tedlar bag (T) sampler was investigated in comparison to polyester aluminum bag (P) sampler. To derive the comparative data sets for the relative performance between different samplers, a series of calibration experiments were performed by using 1 ppb standard of four offensive reduced sulfur compounds (RSC) odorants ($H_2S$, $CH_3SH$, DMS, and DMDS) along with $SO_2$ and $CS_2$. All the analysis was made by gas chromatography/pulsed flame photometric detector (GC/PFPD) combined with air server/thermal desorber (AS/TD). The measurement data were obtained by loading gaseous standards (1 ppb) at 3 injection volumes (250, 500 and 1,000 mL) at three intervals (0, 24 and 72 hrs). The recovery rates (RR) of P sampler were computed against the slope values of T sampler. According to our analysis, P sampler exhibits slightly enhanced loss relative to T, especially with light RSCs ($H_2S$ and $CH_3SH$). At day 0, RR for the two were 88 and 85%, respectively. Such reduction proceeded rather rapidly in the case of $H_2S$ through time. However, P sampler was more stable to store $SO_2$ unlike others. Despite slightly reduced recovery, P sampler appears as a good replacement of T sampler.

Single Phase 5-level Inverter with DC-link Switches (DC링크 스위치를 갖는 단상 5레벨 인버터)

  • Choi, Young-Tae;Sun, Ho-Dong;Park, Min-Young;Kim, Heung-Geun;Chun, Tea-Won;Nho, Eui-Cheol
    • The Transactions of the Korean Institute of Power Electronics
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    • v.16 no.3
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    • pp.283-292
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    • 2011
  • This paper proposed a new multi-level inverter topology based on a H-bridge with two switches and two diodes connected to the DC-link. The output voltage of the proposed topology is quite closer to a sinusoidal waveform compared with a typical single phase inverter. The proposed multi-level inverter is applicable to a power conditioning system for renewable energy sources, and it can be also used as a building block of a cascaded multi-level inverter for a high voltage application. In case of conventional H-bridge type or NPC type multi-level inverter, 8 controllable switches are used to obtain a 5 level output voltage, but the proposed multi-level inverter requires only 6 controllable switches. Thus the circuit configuration is quite simple, reliable and cost-effective implementation is possible. The efficiency can be improved owing to the reduction of the switching loss. A new PWM method based on POD modulation is suggested which requires only one carrier signal. The switching sequence to make the capacitor voltage balanced is also considered. The feasibility is studied through simulation and experiment.

A Study on the Weight Reduction of PET Microfibre Treated with Sodium Diethylene Glycolate (SDEG) (Sodium Diethylene Glycolate (SDEG)에 의한 Polyester 신합섬직물의 감량가공에 관한 연구)

  • Lee, Joo-Hyoung;Kim, Sam-Soo;Huh, Man-Woo;Yoon, Jong-Ho;Cho, Yong-Suk
    • Textile Coloration and Finishing
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    • v.8 no.3
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    • pp.36-51
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    • 1996
  • In order to investigate the degradation behavior of PET fabrics, sodium diethylene glycolate (SDEG)-diethylene glycol (DEG) solutions were prepared and PET fabrics were treated in the solution. The dissolution rate constant and apparent activation energy of the PET fabrics were calculated by Eyring's and Arrhenius's equation respectively and measured dyeing properties, moisture and antistatic properties. Then compared SDEG-treated fabrics with NaOH-treated. The results were as follows; 1. PET fabrics decreased their weight in SDEG-DEG solution, and the decreasing rate showed a linear relationship to the treating time at constant temperature and concentration of SDEG-DEG solution. 2. The dissolution rate constant showed a linear relationship to the concentration of SDEGDEG solution and an exponential relationship to treating temperature. 3. Apparent activation energy of dissolution was 23.45 kcal/mol. 4. The K/S values and the ΔL values of fabrics treated with SDEG-DEG solution are higher and lower respectively than fabrics treated with NaOH. 5. SDEG-DEG solution treatment improved fabric's moisture regain and it reached almost maximum at about 40% weight loss. 6. In the both reagent the light, wet and sublimation fastness of fabrics are similar. 7. SDEG-DEG solution gave more electrical discharge effect to the fabrics than that of NaOH. 8. NaOH treated PET microfiber have crater-like surface, while SDEG-DEG solution give bathochromic effect to the PET microfiber because which has wrinkles on the surface.

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The Influence of Fe Particle Size on the Critical Properties of MgB2 Superconductor (MgB2 초전도체의 임계특성에 대한 Fe 입자 크기의 영향)

  • Jeong, Hyeondeok;Lee, Dong-Gun;Ryu, Sung-Soo;Park, Hai-Woong;Kim, Chan-Joong;Jun, Byung-Hyuk
    • Journal of Powder Materials
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    • v.26 no.5
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    • pp.432-436
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    • 2019
  • This study demonstrates the effect of addition of Fe particles of different sizes on the critical properties of the superconductor $MgB_2$. Bulk $MgB_2$ is synthesized by ball milling Mg and B powders with Fe particles at $900^{\circ}C$. When Fe particles with size less than $10{\mu}m$ are added in $MgB_2$, they easily react with B and form the FeB phase, resulting in a reduction in the amount of the $MgB_2$ phase and deterioration of the crystallinity. Accordingly, both the critical temperature and the critical current density are significantly reduced. On the other hand, when larger Fe particles are added, the $Fe_2B$ phase forms instead of FeB due to the lower reactivity of Fe toward B. Accordingly, negligible loss of B occurs, and the critical properties are found to be similar to those of the intact $MgB_2$.

Fabrication of a Porous Copper Current Collector Using a Facile Chemical Etching to Alleviate Degradation of a Silicon-Dominant Li-ion Battery Anode

  • Choi, Hongsuk;Kim, Subin;Song, Hayong;Suh, Seokho;Kim, Hyeong-Jin;Eom, KwangSup
    • Corrosion Science and Technology
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    • v.20 no.5
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    • pp.249-255
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    • 2021
  • In this work, we proposed a facile method to fabricate the three-dimensional porous copper current collector (3D Cu CC) for a Si-dominant anode in a Li-ion battery (LiB). The 3D Cu CC was prepared by combining chemical etching and thermal reduction from a planar copper foil. It had a porous layer employing micro-sized Cu balls with a large surface area. In particular, it had strengthened attachment of Si-dominant active material on the CC compared to a planar 2D copper foil. Moreover, the increased contact area between a Si-dominant active material and the 3D Cu could minimize contact loss of active materials from a CC. As a result of a battery test, Si-dominant active materials on 3D Cu showed higher cyclic performance and rate-capability than those on a conventional planar copper foil. Specifically, the Si electrode employing 3D Cu exhibited an areal capacity of 0.9 mAh cm-2 at the 300th cycles (@ 1.0 mA cm-2), which was 5.6 times higher than that on the 2D copper foil (0.16 mAh cm-2).

Protective Effect of Phragmitis Rhizoma against Oxidative Stress-induced DNA Damage and Apoptosis in Chang Liver Cells (산화적 스트레스에 의한 간세포의 DNA 손상 및 apoptosis 유도에 대한 노근 추출물의 보호 효과)

  • Lee, Hui yeong;Hong, Sang hoon;Park, Sang eun
    • The Journal of Internal Korean Medicine
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    • v.42 no.6
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    • pp.1269-1284
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    • 2021
  • Objectives: Phragmitis Rhizoma is the fresh or dried rhizome of Phragmites communis Trin., which has been prescribed in traditional Korean medicine to relieve fever and vomiting and to nourish the body fluids. Recently, the protective effect of Phragmitis Rhizoma extract or its components on myelotoxicity and inflammatory responses have been reported, but no study has yet been conducted on oxidative stress. Methods: The present study investigated whether an ethanol extract of Phragmitis Rhizoma (PR) could protect against cellular damage induced by oxidative stress in Chang liver cells. Results: Pretreatment with PR significantly suppressed the hydrogen peroxide (H2O2)-induced reduction of Chang cell viability and generation of reactive oxygen species (ROS), thereby deferring apoptosis. PR also markedly inhibited H2O2-induced comet tail formation and phospho-γH2AX expression, suggesting that PR protected against oxidative stress-mediated DNA damage. PR also effectively prevented the inhibition of ATP synthesis in H2O2-treated Chang cells by inhibiting the loss of mitochondrial membrane potential, indicating that PR maintains energy metabolism through preservation of mitochondrial function while eliminating ROS generated by H2O2. Immunoblotting results indicated that PR attenuated the H2O2-induced downregulation of Bcl-2 and upregulation of Bax expression. Conclusions: PR protects against oxidative injury in Chang liver cells by regulating energy homeostasis via ROS generation blockade, which is at least partly mediated through inactivation of the mitochondria-mediated apoptosis pathway.

Effect of Lodging on soybean yield and other important agronomic characters (도복이 대두의 수량 및 기타 형질에 미치는 영향)

  • Kwon, S.H.;Kim, J.R.
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.24 no.1
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    • pp.73-77
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    • 1979
  • An artificial lodging was made at various growth stages of the soybean varieties Clark and KAS 100-3-1 to evaluate its effect on seed yield and other important agronomic characters. Results showed general increases in plant height and number of branches per plant whereas reductions in seed weight. number of nodes, pods and seeds per plant in the severly lodged plots. As compared to prevention of lodging, about 40 percent yield reduction was caused by the severe lodging treatrment. Furthermore, the most severe lodging before blooming resulted in about 66% yield loss.

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Mass Transfer Characteristics during the Osmotic Dehydration Process of Apples (사과의 삼투건조시 물질이동 특성)

  • 윤광섭;최용희
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.25 no.5
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    • pp.824-830
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    • 1996
  • In order to minimize the deterioration of osmotic dried apple quality, the characteristics of mass transfer during osmotic dehydration such as solid gain(SG), weight reduction(WR) and moisture loss(ML) were investigated. Moisture and solid transfer were analyzed by Fick's law. The highest (equation omitted)E value was observed with severe browning at $60^{\circ}C.$ The concentration effect on (equation omitted)E were higher at high temperatures than at low temperatures. SG, WR and ML increased as immersion temperature, sugar concentration and immersion time increased. Higher concentration of sucrose led to more sucrose absorption resulting increase in SG. Diffusion coefficients of moisture increased with immersion temperature and sugar concentration. As concentration increased, diffusion coefficients of solids increased at $20^{\circ}C$ while it decreased at $40^{\circ}C$ and $60^{\circ}C.$ Arrhenius equation was appropriately explain the effect of temperature on diffusion coefficients. Moisture and solid diffusion showed high activation energy in 20 。Brix solution, compared with in 40 and 60 。Brix.

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