• Title/Summary/Keyword: pH control strategy

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The Effect of Question-Generating Strategy for Science Inquiry Instruction in Elementary Science Class (초등과학 탐구수업에서 문제생성 학습전략의 효과)

  • Kim, Hye Ran;Choi, Sun Young;Lee, Kil Jae
    • Journal of Korean Elementary Science Education
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    • v.33 no.4
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    • pp.700-709
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    • 2014
  • The purpose of this study was to examine the effects of question-generating strategy on science academic achievement, scientific attitude in elementary science class. To examine the effects of question-generating strategy this learning materials were applied to elementary science curriculum, and an experimental group and a control group were selected from $5^{th}$ graders at H elementary school located in Gyeonggi-do. Students were taught for 6 weeks. Control group take traditional lessons and solve questions presented textbook. Question generated group generate questions, solve them and feed back by themselves. The results of this study were found statistically significant difference in the pupil's enhancement of the science academic achievement, scientific attitude (p<.05). Thus question-generating strategy for elementary science inquiry instruction that has a positive effect on interests in class is useful and better be widely applied to science education.

A Strategy to Increase Microbial Hydrogen Production, Facilitating Intracellular Energy Reserves

  • Lee, Hyo Jung;Park, Jihoon;Lee, Joo-Young;Kim, Pil
    • Journal of Microbiology and Biotechnology
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    • v.26 no.8
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    • pp.1452-1456
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    • 2016
  • Overexpression of the genes encoding phosphoeneolpyruvate carboxykinase (pckA) and NAD-dependent malic enzyme (maeA) facilitates higher intracellular ATP and NAD(P)H concentrations, respectively, under aerobic conditions in Escherichia coli. To verify a hypothesis that higher intracellular energy reserves might contribute to H2 fermentation, wild-type E. coli strains overexpressing pckA and maeA were cultured under anaerobic conditions in a glucose minimal medium. Overexpression of pckA and maeA enabled E. coli to produce 3-times and 4-times greater H2 (193 and 284 nmol, respectively) than the wild type (66 nmol H2). The pckA and maeA genes were further overexpressed in a hydrogenase-3-enhanced E. coli strain. The hydrogenase-3-enhanced strain (W3110+fhlA) produced 322 nmol H2, whereas the ATP-enhanced strain (W3110+fhlA+pckA) produced 50% increased H2 (443 nmol). Total H2 in the NAD(P)H-enhanced strain (W3110+fhlA+maeA) was similar to that in the control strain at 319 nmol H2. Possible explanations for the contribution of the increased cellular energy reserves to the enhanced hydrogen fermentation observed are discussed based on the viewpoint of metabolic engineering strategy.

Cascaded H-Bridge Five Level Inverter for Grid Connected PV System using PID Controller

  • Sivagamasundari, M.S.;Mary, P. Melba
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.4
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    • pp.451-462
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    • 2016
  • Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

Rapamycin treatment during prolonged in vitro maturation enhances the developmental competence of immature porcine oocytes

  • Seung-Eun Lee;Han-Bi Lee;Jae-Wook Yoon;Hyo-Jin Park;So-Hee Kim;Dong-Hun Han;Eun-Seo Lim;Eun-Young Kim;Se-Pill Park
    • Journal of Animal Science and Technology
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    • v.66 no.5
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    • pp.905-919
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    • 2024
  • Porcine oocytes undergo in vitro maturation (IVM) for 42-44 h. During this period, most oocytes proceed to metaphase and then to pro-metaphase if the nucleus has sufficiently matured. Forty-four hours is sufficient for oocyte nuclear maturation but not for full maturation of the oocyte cytoplasm. This study investigated the influences of extension of the IVM duration with rapamycin treatment on molecular maturation factors. The phospho-p44/42 mitogen-activated protein kinase (MAPK) level was enhanced in comparison with the total p44/42 MAPK level after 52 h of IVM. Oocytes were treated with and without 10 µM rapamycin (10 R and 0 R, respectively) and examined after 52 h of IVM, whereas control oocytes were examined after 44 h of IVM. Phospho-p44/42 MAPK activity was upregulated the 10 R and 0 R oocytes than in control oocytes. The expression levels of maternal genes were highest in 10 R oocytes and were higher in 0 R oocytes than in control oocytes. Reactive oxygen species (ROS) activity was dramatically increased in 0 R oocytes but was similar in 10 R and control oocytes. The 10 R group exhibited an increased embryo development rate, a higher total cell number per blastocyst, and decreased DNA fragmentation. The mRNA level of development-related (POU5F1 and NANOG) mRNA, oocyte-apoptotic (BCL2L1) genes were highest in 10 R blastocysts. These results suggest that prolonged IVM duration with rapamycin treatment represses ROS production and increases expression of molecular maturation factors. Therefore, this is a good strategy to enhance the developmental capacity in porcine oocytes.

Design of Power System Stabilizer using QFT (QFT를 이용한 전력 계통 안정화 장치 설계)

  • Lee, J.P.;Chung, H.H.;Kim, C.H.;Chung, H.H.
    • Proceedings of the KIEE Conference
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    • 2000.11a
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    • pp.187-189
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    • 2000
  • In this paper, QFT robust control strategy is proposed to improve stability of power systems in the presence of parametric uncertainty. The basic idea in QFT is to convert design specifications of a closed loop system and plant uncertainties into robust stability and performance bounds on the open loop transmission of the nominal system and then to design a controller by using the gain-phase loop sharing technique. The robustness of the QFT controller has been investigated on a single machine infinite bus model by nonlinear simulations.

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A Novel Pulse Density Modulated High Frequency Inverter for Streamer Reactor (스트리머 발생을 위한 새로운 PDM 고주파 인버터)

  • Kim, J.Y.;Mun, S.P.;Suh, K.Y.;Lee, H.W.;Jung, J.G.
    • Proceedings of the KIEE Conference
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    • 2005.10c
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    • pp.223-225
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    • 2005
  • This paper presents a novel prototype of a current source resonant inverter using insulated gate bipolar transistors for driving a streamer reactor, streamer generation technology has been recognized as one of the best methods for water treatment, disinfection, industrial wastes utilization, and so on. However, some technological difficulties related to efficient streamer production have been significant problems restricting streamer usage in the industrial plants. Introduced in this paper is a pulse density modulated high frequency inverter for a plasma generate, which is developed with the aim to improve power conversion and control characteristics of the streamer reactor by using advances in power electronic technology. The developed system implements the feedforward control-based pulse density modulation control scheme with pulse width modulation feedback control strategy to compensate temperature and other environmental influences on streamer discharge.

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Inhibitory Effect of Persicaria perfoliata (L.) H. Gross on IgE Mediated Allergic Responses in RBL-2H3 Cells

  • Yoon, Hyun-Seo;Park, Chung-Mu
    • Journal of The Korean Society of Integrative Medicine
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    • v.8 no.4
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    • pp.163-169
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    • 2020
  • Purpose : This study aimed to investigate the anti-allergic effect of Persicaria perfoliata water extract (PPWE) on IgE stimulated rat basophilic leukemia (RBL-2H3) cell line. Methods : P. perfoliata (L.) H. Gross has been used in traditional medicine as an anti-allergic agent, antipyretic, and diuretic and for respiratory disorders. To analyze the anti-allergic activity of PPWE, release of β-hexosaminidase in RBL-2H3 cells was estimated by enzyme linked immunosorbant assay (ELISA). Also, the cytotoxic effect of PPWE was identified by WST assay, and nuclear factor (NF)-κB and its upstream signaling molecules were assessed by western blot analysis. Results : PPWE treatment significantly attenuated β-hexosaminidase release in a dose dependent manner without any cytotoxicity. PPWE inhibited β-hexosaminidase activity by 38.4±1.2, 36.6±0.6, 32.5±2.2 and 26.5±1.2 at 500, 250, 100, and 50 ㎍/㎖ of PPWE, respectively, compared with the control group. In addition, an analysis of the expression level of NF-κB, an inflammation transcription factor, in RBL-2H3 cells upon IgE stimulation provided reults consistent with the results of β-hexosaminidase release. The phosphorylated status of upstream signaling molecules for transcription factor, mitogen activated protein kinases (MAPKs), was also analyzed. The results showed that PPWE treatment dose-dependently inhibited phosphorylation of extracellular regulatory kinase (ERK) and c-Jun N-terminal kinase (JNK). These results show that PPWE had a strong IgE-mediated degranulation inhibitory effect on RBL-2H3 cells. Conclusion : P. perfoliata ameliorated IgE-mediated allergic reaction via the modulation of MAPK and NF-κB signaling pathway in RBL-2H3 cells. These results indicate that P. perfoliata could be a potential candidate for a treatment strategy against various allergic disorders.

Evaluation of Dietary Supplementation of Delta-aminolevulinic Acid and Chito-oligosaccharide on Production Performance, Egg Quality and Hematological Characteristics in Laying Hens

  • Yan, L.;Lee, J.H.;Meng, Q.W.;Ao, X.;Kim, I.H.
    • Asian-Australasian Journal of Animal Sciences
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    • v.23 no.8
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    • pp.1028-1033
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    • 2010
  • The effects of delta-aminolevulinic acid (DALA) or chito-oligosaccharide (COS) in layer diets on production performance, egg quality and hematological characteristics were investigated in this 8-week trial. Two hundred and seventy 27-week-old (Hy-Line brown) layers were randomly assigned to 5 treatments with 9 replications per treatment. Dietary treatments were i) Control (basal diet); ii) DALA1 (basal diet+DALA 2 mg/kg); iii) DALA2 (basal diet+DALA 4 mg/kg); iv) COS1 (basal diet+COS 100 mg/kg) and v) COS2 (basal diet+COS 200 mg/kg). In this study, no significant difference was observed in feed intake and egg shell quality (eggshell breaking strength and egg shell thickness) among treatments. The inclusion of DALA increased egg production during the first 4 weeks. Egg weight was increased in both DALA (quadratic, p<0.05) and COS (linear, p<0.05) treatments compared with the control treatment. Laying hens fed the DALA treatment had an increased yolk color unit (quadratic, p<0.05) and haugh unit (linear, p<0.05) compared with the control group. Similarly, these characteristics were also affected by COS treatments, with both values being linearly increased (p<0.05) in COS treatments compared with the control treatment. Additionally, birds fed DALA treatments significantly increased (quadratic, p<0.05) the number of RBC, WBC and lymphocytes compared with the control treatment. Dietary DALA supplementation linearly increased (p<0.05) the serum iron concentration at the end of the 8th week. The inclusion of COS increased (linear, p<0.05) the concentration of RBC, WBC and lymphocytes compared with the control treatment. In conclusion, dietary DALA at the lower dosage (2 mg/kg) could exert better effects in laying hens than higher dosage (4 mg/kg). Birds fed DALA supplemented diet had an increased iron availability, egg weight, eggshell quality and immunity. Moreover, the inclusion of COS (200 mg/kg) can increase egg weight, eggshell quality and immunity in laying hens. Therefore, both the utilization of COS and DALA could be considered as a new strategy for optimizing egg quality and health condition of laying hens.

Effects of Supplementation of Mixed Cassava (Manihot esculenta) and Legume (Phaseolus calcaratus) Fodder on the Rumen Degradability and Performance of Growing Cattle

  • Thang, C.M.;Sanh, M.V.;Wiktorsson, H.
    • Asian-Australasian Journal of Animal Sciences
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    • v.21 no.1
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    • pp.66-74
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    • 2008
  • Two experiments were conducted to assess the effect of replacing a conventional concentrate with mixed cassava (Manihot esculenta) foliage and legume (Phaseolus calcaratus) foliage. In Exp. 1, three rumen fistulated crossbred cows were used for in sacco rumen degradability studies. In vitro gas production was also studied. In Exp. 2, 11 crossbred F2 heifers (Red Sindhi$\times$Holstein Friesian), with initial live weight of $129{\pm}6kg$ and aged six months, were allocated in a Completely Randomized Design (CRD) to evaluate a mixture (ratio 3:1) of cassava and legume foliage (CA-LE feed) as a protein source compared to a traditional concentrate feed (Control) in diets based on fresh elephant grass (Pennisetum purpureum) and urea treated rice straw ad libitum. The Control feed was replaced by the CA-LE feed at levels of 0% (Control), 40% (CA-LE40), and 60% (CA-LE60) based on dry matter (DM). The in sacco degradation of CA-LE feed was higher than Control feed (p<0.05). After 48 h incubation the degradation of CA-LE feed and Control feed was 73% vs. 58% of DM and 83% vs. 65% of CP, respectively. The gas production of CA-LE feed was also significantly higher than of Control feed during the first 12 h of incubation. The results of the performance study (Exp. 2) showed that the level of CA-LE feed in the concentrate had no effect on total dry matter intake (p>0.05), but live weight gains (LWG) in CA-LE40 and CA-LE60 were significantly higher (551 and 609 g/d, respectively) than in the Control group (281 g/d). The intake of CP was higher (p<0.05) for the treatments CA-LE40 and CA-LE60 (556 and 590 g/d, respectively) compared to that of Control (458 g/d), while there was no significant difference in ME intake. The feed conversion ratio was 16.8, 9.0 and 7.9 kg DM/kg LWG in Control, CA-LE40 and CA-LE60, respectively. The feed cost of CA-LE40 and CA-LE60 corresponded to 43% and 35%, respectively, of the feed cost of Control feed. The best results were found when CA-LE feed replaced 60% of DM in Control feed and considerably decreased feed cost. It is concluded that feeding cassava foliage in combination with Phaseolus calcaratus legume as a protein supplement could be a potentially valuable strategy which leads to reduced feed costs and a more sustainable system in smallholder dairy production in Vietnam.

A study on Characteristics analysis of time sharing type high frequency inverter consisting of half-bridge serial resonant inverter (Half-Bridge형 시분할방식 고주파 공진 인버터의 특성해석에 관한 연구)

  • Cho G. P.;Shin G. H.;Won J. S.;Kim D. H.;Ro C. G.;Sim K. Y.;Bae Y. H.
    • Proceedings of the KIPE Conference
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    • 2001.07a
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    • pp.344-347
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    • 2001
  • A high frequency resonant inverter consisting of three unit half-bridge serial resonant inverter used as power source of induction heating at high frequency is presented in this paper. As a output power control strategy, tine-sharing gate control method is applied. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, according to the calculated characteristics value, a method of the circuit design and operating characteristics of the inverter is proposed. This paper proves the validity of theoretical analysis through the experiment. This proposed inverter show that it can be practically used in future as power source system for induction heating application, DC-DC converter etc.

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