엽록소 농도 결정을 위하여 측정한 흡광도 값의 신뢰도 검정 지표로서 엽록소 a/b 비례치

오광석(Guangxi Wu),이춘환(Choon-Hwan Lee) 한국생명과학회 2019 생명과학회지 Vol.29 No.5

비어·람버트 법칙에 의하면 충분히 묽은 용액에서 주어진 파장에서 측정한 흡광도는 용질의 농도에 비례한다. 반대로 충분히 묽은 용액이란 측정한 흡광도 값이 용질의 농도에 비례관계를 가지는 범위에 있는 용액을 말하지만 실제 확신하기가 어렵다. 본 연구에서는 벼 잎에서 추출한 엽록소 80% 아세톤 용액을 사용하여, 측정한 흡광도 값의 신뢰도를 판단할 수 있는 기준으로서 엽록소 a/b 비례치의 사용 가능성을 4가지 다른 흡광분광분석기(Cary4E, UV-1650PC, Versamax, NanoDrop 100)을 사용하여 조사하였다: 우선 0.2 ㎍/ml의 매우 저농도에서 200 ㎍/ml까지의 다양하게 희석한 엽록소 용액을 사용하여, 645 ㎚와 663 ㎚에서 측정한 흡광도 값을 측정한 후, 흡광도 값과 엽록소 농도의 비례관계를 조사하였다. 그 결과, 이 비례관계로 판단한 측정치의 신뢰 범위에서 흡광도로부터 계산한 용액에서의 엽록소 농도와 이미 알고 있는 엽록소 농도 비교적 일치하였다. 그러나, 비례관계의 한계치 안에 있어 신뢰도가 인정된 일부 고농도와 저농도에서의 일부 값이 엽록소 a/b 비례치가 용액의 희석에 변화지 않을 것이라는 판단 기준에 있어 신뢰도가 떨어짐을 알 수 있었다. 그러므로, 본 연구결과는 엽록소 농도 결정을 위하여 측정한 흡광도 값의 신뢰 여부는 대상 용액을 희석하여 측정한 흡광도의 비례관계로 본 비어-램버트 법칙의 기준 보다는 엽록소 a/b 비례치가 변하지 않는다는 기준으로 측정치의 신뢰도를 판단하는 것이 더 좋다는 것을 확인할 수 있었다. The Beer-Lambert law states that absorbance is proportional to the concentration of a solute in a solution at a given wavelength. This linearity works for an ideal or a ‘sufficiently diluted’ solution, so this linearity is often used as a criterion for the fidelity of the absorbance value measured. In this study, we used a chlorophyll (Chl) solution, isolated from rice leaves with 80% acetone to test the use of the Chl a/b ratio as an additional criterion for checking the fidelity of measured values using four different absorption spectrophotometers: Cary4E, UV-1650PC, Versamax (a microplate reader), and NanoDrop 1,000(which can handle a 4 μl aliquot). We used Chl solutions of varying concentrations from 0.2 ㎍/ml to 200 ㎍/ml to measure absorbance values at 645 ㎚ and 663 ㎚ and checked the linearity first. The results indicated that the range of Chl concentrations that we can rely on based on the linearity was similar to the range in which the calculated Chl concentrations based on the measured absorbance values agreed with the known concentrations. However, some border cases or cases with very low Chl concentrations inside the fidelity range of Chl concentrations did not agree with the criterion that the Chl a/b ratio should not change after dilution of the Chl in the solution. These results suggest that the Chl a/b ratio is a better criterion for the reliability of the absorbance values measured for the determination of chlorophyll concentration than the criterion based on the linearity suggested by the Beer-Lambert law.

Design, analyses, and evaluation of a spiral TDR sensor with high spatial resolution

Quan Gao,Guangxi Wu,Xiong Yu 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.4

Time Domain Reflectometry (TDR) has been extensively applied for various laboratory and field studies. Numerous different TDR probes are currently available for measuring soil moisture content and detecting interfaces (i.e., due to landslides or structural failure). This paper describes the development of an innovative spiral-shaped TDR probe that features much higher sensitivity and resolution in detecting interfaces than existing ones. Finite element method (FEM) simulations were conducted to assist the optimization of sensor design. The influence of factors such as wire interval spacing and wire diameter on the sensitivity of the spiral TDR probe were analyzed. A spiral TDR probe was fabricated based on the results of computer-assisted design. A laboratory experimental program was implemented to evaluate its performance. The results show that the spiral TDR sensor featured excellent performance in accurately detecting thin water level variations with high resolution, to the thickness as small as 0.06 cm. Compared with conventional straight TDR probe, the spiral TDR probe has 8 times the resolution in detecting the water level changes. It also achieved 3 times the sensitivity of straight TDR probe.

Differential Down-regulation of Zeaxanthin Epoxidation in Two Rice (Oryza sativa L.) Cultivars with Different Chilling Sensitivities

김호승,Minh Hien Hoang,전영아,Guangxi Wu,이춘환 한국식물학회 2017 Journal of Plant Biology Vol.60 No.4

When the leaf segments of rice (Oryza sativa L.)plants were subjected to chilling in the moderate light,zeaxanthin (Zx) formation was faster in a chilling-tolerantDongjin-byeo (DJ) than in a chilling-sensitive IR841. Althoughthe rate of Zx formation was accelerated by the treatment of5 mM salicylaldoxime, an inhibitor of Zx epoxidase (ZE),there was almost no changes in DJ. A similar result wasobserved when leaf segments were treated with 50 mMsodium fluoride, a potent inhibitor of chloroplast phosphatase. The slow Zx epoxidation in IR841 during light-chilling wasconfirmed in leaf segments treated with 10 mM dithiothreitol,an inhibitor of violaxanthin de-epoxidase (VDE). However,the differences between the two cultivars were not observedat 25oC. These results suggest that compared with IR841 thehigher rate of Zx formation in DJ is not due to the higherVDE activity in DJ but is due to more rapid down-regulationof ZE in DJ, possibly by its phosphorylation. Compared withDJ, IR841 accumulated more superoxide with PSI inactivationduring light-chilling, which eliminates the possibility of increasedZE down-regulation in DJ leaves by photo-oxidation. Invitro study with alkaline phosphatase supports the idea ofdown-regulation of ZE by phosphorylation under light-chillingcondition. We propose that this reversible down-regulation ofZx epoxidation possibly by the phosphorylation of ZE is animportant regulation mechanism of violaxanthin cycle thatconfers chilling tolerance of a rice cultivar under chillingstress in the light with moderate intensities.

Experimental studies on gasification of the Shenmu coal char with CO2 at elevated pressures

Wang Mingmin,Zhang Jiansheng,Zhang Shouyu,Wu Jinhu,Yue Guangxi 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6

The gasification rates of Shenmu coal chars with CO2 were experimentally studied with a pressurized thermo- gravimetric analyzer (PTGA). Shenmu coal is a typical Chinese coal, and the coal char was prepared by a fixedbed reactor in nitrogen at 900 oC. The experiments were carried out in the dynamic heating segments from 750 oC to 1,000 oC, and the reaction pressure increased from 0.1MPa to 3.1MPa with pure CO2. The external diffusion resistances were minimized by increasing the flow rates and decreasing the thickness of sample layer before the test, to ensure the reactions were under kinetic control. The results show that the gasification rates increase proportionally to the 0.1 power of the CO2 partial pressure. The unreacted-core shrinking model was applied to predict the reaction rate by changing the molar fraction of CO2 at 0.6Mpa and 1.6Mpa total pressures, which showed a good match with experimental data.

A Dominant Mutation in ARL2 Causes Impaired Adventitious Root Development in Rice

Shiping Liu,Yanhong Xue,Xiaofei Wang,Botao Zhang,Yuting Bi,Min Qiu,Guangxi Wang,Ping Wu 한국식물학회 2011 Journal of Plant Biology Vol.54 No.4

Adventitious roots are vital for water and nutrient assimilation by cereal crops because they comprise the bulk of the fibrous root system. We isolated and analyzed a rice mutant, adventitious rootless 2 (arl2), which failed to initiate adventitious root primordia during early development. Its seminal root produced fewer lateral roots than from the wild type. This mutant also exhibited pleiotropic phenotypes of longer and thicker seminal roots, a different morphology for the first leaf, delayed heading, and a greater tiller angle. Physiological experiments showed that exogenous auxin and ethylene could rescue adventitious root growth, a response opposite that for two previously reported mutants, arl1 and gnom1. Activity in the auxin signal pathway and the polar auxin transport system was normal for arl2. Compared with the wild type, arl2 plants showed enhanced sensitivity to ethephon but decreased sensitivity to AgNO_3, an inhibitor of ethylene. Genetics analysis demonstrated that this mutant is controlled by a single dominant gene; ARL2 was mapped within a 100-kb interval on the short arm of chromosome 2.

Comparison of Direct and Indirect Electron Transfer to Convert CO2 to Polyhydroxybutyrate in Microbial Electrosynthesis Cell with Rhodobacter sphaeroides

Shuwei LI,Minsoo KIM,Da Seul KONG,Kyoungseon MIN,Guangxi WU,Meiying CUI,Changman KIM,You-Kwan OH,Soek KIM,Soo Youn LEE,Sung Gyun KANG,Yvonne NYGaRD,Jung Rae KIM 한국생물공학회 2023 한국생물공학회 학술대회 Vol.2023 No.4