우리 국민의 나트륨 및 칼륨 섭취량 평가: 식품별 영양성분 함량 DB와 한국형 총 식이조사 기반 추정량 비교 연구

이지연,권성옥,이수현,서민정,이계호,김초일 대한지역사회영양학회 2023 대한지역사회영양학회지 Vol.28 No.3

Objectives: Based on the results from the Korean Total Diet Study (KTDS), the sodium (Na) and potassium (K) intake of Koreans were estimated and compared with intake estimates from the Food & Nutrient Database (FNDB), as in the Korea National Health and Nutrition Examination Survey (KNHANES) to verify the validity of these estimates. Methods: One hundred and thirty-four representative foods (RFs) covering 92.5% of the total food intake of Koreans were selected, and 228 pairs of corresponding ‘RF x representative cooking method’ were derived by reflecting the methods used mainly in terms of frequency and quantity in their cooking. RF samples were collected from three cities with a larger population size in three regions (nine cities) nationwide, and six composite samples were made for each RF, considering its regional and/or seasonal characteristics. One thousand three hundred and sixty-eight ‘RF x representative cooking method’ pair samples were prepared, and the Na and K contents were assessed using inductively coupled plasma atomic emission spectrometry (ICP-MS). The Na and K intake of the Korean population was estimated by linking the content with the food intake data from the 7th KNHANES. Results: The mean Na and K intake of Koreans were 2,807.4 mg and 2,335.0 mg per person per day, respectively. A comparison with the Na and K intake from KNHANES, including only RFs of KTDS, showed comparable results with less than 5% variation. While the contribution and ranking of food items to Na intake were similar between KNHANES and KTDS, there were differences in K intake. This was attributed to the large discrepancies in the K content of rice and coffee between KTDS results and the values in the 9th Revision of the National Food Composition Table used in KNHANES. Conclusions: The Na and K intake of Koreans estimated based on the KTDS, which performed nutrient analysis on samples prepared to a ‘table-ready’ state using foods of the representative collection, was similar and comparable with that of KNHANES. This supports the validity and usefulness of FNDB-based nutrient intake estimation at the population level. The list of nutrients studied in KTDS is expected to be expanded, allowing for intake estimation of nutrients with currently insufficient or absent information in the FNDBs in use.

도라지(Platycodon grandiflorum A. De Candolle) 섭취에 따른 알루미늄의 노출량 평가

김성단(Sung-Dan Kim),함희진(Hee-Jin Ham),정지헌(Ji-Hun Jung),이은순(Eun-Soon Lee),이현경(Hyun-Kyung Lee),김희선(Hee-Sun Kim),이집호(Jib-Ho Lee),유인실(In-Sil Yu),정권(Kweon Jung) 한국식품영양과학회 2016 한국식품영양과학회지 Vol.45 No.8

2014~2015년 서울시내 대형마트, 소형마트 및 재래시장 등에서 유통 중인 천연 및 단순가공 도라지 총 93건(깐도라지 53건, 피도라지 40건)의 알루미늄 잔류량을 분석한 결과 평균 및 95th percentile 알루미늄 잔류량은 72.989(0.54~564.38) mg/kg 및 471.32 mg/kg이었다. 깐도라지 53건의 평균 및 95th percentile 알루미늄 잔류량은 121.235(0.54~564.38) mg/kg 및 545.622 mg/kg이었으며, 피도라지 40건의 평균 및 95th percentile 알루미늄 잔류량은 9.063(0.72~28.05) mg/kg 및 26.379 mg/kg이었다. 단순가공 깐도라지의 평균 알루미늄 잔류량은 천연 상태 피도라지에 비해 13.4배 높은 수준으로 유의적인 차이가 있었다(P<0.001). 도라지의 알루미늄 분석값과 제6기 1차 연도(2013년)의 국민건강영양조사 중 영양조사(조사1일 전 식품섭취 내용, 24시간 회상법)의 도라지 섭취량 평균값, 최소값, 최대값 및 95th percentile 값을 이용하여 단일값 분석을 실시하여 추정식이섭취량(estimated daily intake, EDI)을 산출한 결과 영양조사 대상자 전체(시나리오Ⅰ)의 도라지 섭취를 통한 평균 알루미늄 EDI는 0.001(~1.363) mg/kg bw/d였으며, 섭취자군(시나리오Ⅱ)의 평균 및 95th percentile EDI는 각각 0.033(0.000~1.309) 및 0.610 mg/kg bw/d였다. 도라지 섭취량을 연중 일상섭취량으로 가정하여 추정주간식이섭취량(estimated weekly intake, EWI)을 산출하여 잠정주간섭취허용량(provisional tolerable weekly intake, PTWI)과 비교하여 평가한 결과 섭취자군(시나리오 Ⅱ)의 평균 추정주간식이섭취량은 0.231 mg/kg bw/week(23.1% PTWI)였다. This study was performed to estimate daily intakes of aluminum from Platycodon grandiflorum A. De Candolle and evaluate their potential health risks for Koreans. Estimated daily intake of aluminum was calculated, whereas the actual level of aluminum in Platycodon grandiflorum A. De Candolle was analyzed using inductively coupled plasma mass spectrometry. Food consumption amount was drawn from Korea National Health and Nutrition Examination Survey (KNHANES Ⅵ-1). In analysed samples, aluminum values ranged from 0.54∼564.38 mg/kg in peeled Platycodon grandiflorum A. De Candolle samples (n=53) and from 0.72∼28.05 mg/kg in unpeeled ones (n=40). Statistically significant difference (P<0.001) was detected according to the type of skin. To estimate the dietary intake of Platycodon grandiflorum A. De Candolle, a total of 7,242 respondents (scenario Ⅰ) were compared to 227 Platycodon grandiflorum A. De Candolle consumption subjects (scenario Ⅱ). Estimated daily intake of aluminum was calculated based on point estimates. Level of safety for aluminum was evaluated by comparison with Provisional Tolerable Weekly Intake (PTWI), 1 mg/kg bw, set by the Joint FAO/WHO Expert Committee on Food Additives. For scenario Ⅰ, mean estimated daily intake of aluminum was 0.001 mg/kg bw/d. For scenario Ⅱ, mean estimated daily intake of aluminum was 0.033 mg/kg bw/d, and 95th percentile estimated daily intake was 0.610 mg/kg bw/d. For scenario Ⅱ, aluminum from Platycodon grandiflorum A. De Candolle had a mean weekly intake that was the 23.1% of PTWI.

일반인의 납 경구섭취량의 경시적 변화 : 2008-2018년 국내자료를 중심으로

문찬석(Chan-Seok Moon) 한국환경보건학회 2021 한국환경보건학회지 Vol.47 No.1

Objectives: The study aims to examine the variation over roughly the past 10 years (from 2008 to 2018) in the estimated daily dietary Pb intake (Pb-D) based on the variations of daily intake amount and Pb content in respective food groups. The following factors were considered: (1) variation of estimated value of Pb-D, (2) Pb contents in each food group and (3) the most influential food group for dietary Pb intake. Methods: Estimated values of Pb-D were taken from food consumption by the food groups reported in the Korean National Health and Nutrition Survey and the Pb content of each food group as reported in 19 previous publications. Variation from 2008 to 2018 of Pb intake was calculated from daily intake amount and Pb content in each food group. Results: The survey showed that main Pb intake sources were the food groups ‘meats and poultry’ and ‘fish and shellfish’. These food groups showed gradually increased Pb exposure from 2008 to 2018. Estimated daily Pb intake was 42.18 to 57.68 µg/day for men and 30.97 to 42.54 µg/day for women. Both men and women showed slightly increased dietary Pb intake from 2008 to 2018. The food groups ‘meats and poultry’ and ‘fish and shellfish’ proved the highest Pb intake food groups. Estimated Pb intake from ‘meats and poultry’ was 8.47 to 12.98 µg/day and that of ‘fish and shellfish’ was 5.63 to 10.10 µg/day. Conclusion: Over the past ten years, daily Pb intake has slightly increased in men and women. The food groups ‘meats and poultry’ and ‘fish and shellfish’ might be the main variation factors of Pb intake.

어린이와 청소년의 비알콜성음료 섭취에 따른 다량무기질 섭취량 평가

김성단(Kim, Sung Dan),문현경(Moon, Hyun-Kyung),박주성(Park, Ju Sung),이용철(Lee, Yong Chul),신기영(Shin, Gi Young),조한빈(Jo, Han Bin),김복순(Kim, Bog Soon),김정헌(Kim, Jung Hun),채영주(Chae, Young Zoo) 한국영양학회 2013 Journal of Nutrition and Health Vol.46 No.1

The aims of this study were to estimate daily intake of macrominerals from beverages, liquid teas, and liquid coffees and to evaluate their potential health risks for Korean children and adolescents (1-to 19 years old). Assessment of dietary intake was conducted using the actual level of sodium, calcium, phosphorus, potassium, and magnesium in non-alcoholic beverages and (207 beverages, 19 liquid teas, and 24 liquid coffees) the food consumption amount drawn from “The Fourth Korea National Health and Nutrition Examination Survey (2007-2009)”. To estimate the dietary intake of nonalcoholic beverages, 6,082 children and adolescents (Scenario I) were compared with 1,704 non-alcoholic beverage consumption subjects among them (Scenario II). Calculation of the estimated daily intake of macrominerals was based on point estimates and probabilistic estimates. The values of probabilistic macromineral intake, which is a Monte-Carlo approach considering probabilistic density functions of variables, were presented using the probabilistic model. The level of safety for macrominerals was evaluated by comparison with population nutrient intake goal (Goal, 2.0 g/day) for sodium, tolerable upper intake level (UL) for calcium (2,500 mg/day) and phosphorus (3,000-3,500 mg/day) set by the Korean Nutrition Society (Dietary Reference Intakes for Koreans, KDRI). For total children and adolescents (Scenario I), mean daily intake of sodium, calcium, phosphorus, potassium, and magnesium estimated by probabilistic estimates using Monte Carlo simulation was, respectively, 7.93, 10.92, 6.73, 23.41, and 1.11, and 95th percentile daily intake of those was, respectively, 28.02, 44.86, 27.43, 98.14, and 3.87 mg/day. For consumers-only (Scenario II), mean daily intake of sodium, calcium, phosphorus, potassium, and magnesium estimated by probabilistic estimates using Monte Carlo simulation was, respectively, 19.10, 25.77, 15.83, 56.56, and 2.86 mg/day, and 95th percentile daily intake of those was, respectively, 62.67, 101.95, 62.09, 227.92, and 8.67 mg/day. For Scenarios I·II, sodium, calcium, and phosphorus did not have a mean an 95th percentile intake that met or exceeded the 5% of Goal and UL. (Korean J Nutr 2013; 46(1): 50 ~ 60)

어린이와 청소년의 비알콜성음료 섭취에 따른 인공감미료 섭취량 평가

김성단(Sung-Dan Kim),문현경(Hyun-Kyung Moon),이집호(Jib-Ho Lee),장민수(Min-Su Chang),신영(Young Shin),정선옥(Sun-Ok Jung),윤은선(Eun-Sun Yun),조한빈(Han-Bin Jo),김정헌(Jung-Hun Kim) 한국식품영양과학회 2014 한국식품영양과학회지 Vol.43 No.8

본 연구는 음료 651건 및 액상차 87건의 인공감미료 실측치(아스파탐, 아세설팜칼륨 및 수크랄로스)와 제4기 국민건강영양조사 중 영양조사의 섭취량을 이용하여 단위 체중당 비알콜성음료 섭취량이 가장 높았던 1~19세의 어린이 및 청소년을 대상으로 비알콜성음료를 통한 인공감미료의 추정식이섭취량(estimated daily intake, EDI)을 산출하여 평가하였다. 비알콜성음료의 섭취량은 어린이 및 청소년 6,082명 전체의 비알콜성음료의 평균소비자(average consumer)와 극단소비자(extreme consumer)의 섭취량을 파악하기 위하여 평균, 95 percentile 및 분포를 적용한 경우(시나리오Ⅰ)와 비알콜성음료를 섭취한 어린이와 청소년 1,074명의 섭취량 평균, 95 percentile 및 분포를 적용한 경우(시나리오Ⅱ)로 나누어 살펴보았다. 음료에 함유된 인공감미료의 건강 위해성 평가는 추정식이섭취량과 FAO/WHO에서 설정한 일일섭취허용량(acceptable daily intake, ADI)인 아스파탐 40 mg/kg bw/day, 아세설팜칼륨 15 mg/kg bw/day, 수크랄로스 15 mg/kg bw/day 값을 비교하여 %ADI로 평가를 하였다. 인공감미료의 인체노출량 계산에 필요한 몸무게는 국민건강영양조사 검진조사 자료를 이용하였다. 이때 위해도 평가방법은 평균과 95th percentile을 이용하는 단일값평가와 각 변수의 확률밀도함수(probabilistic density functions, PDFs)를 이용한 Monte Carlo simulation을 실시하여 확률평가를 하였다. 연구 결과를 요약하면 인공감미료는 아스파탐, 아세설탐칼륨, 수크랄로스가 평균 3.21±28.36 mg/kg(ND~342.00 mg/kg, 검출률 1.4%), 1.94±12.55 mg/kg(ND~160.00 mg/kg, 검출률 4.5%), 6.18±23.27 mg/kg(ND~290.00 mg/kg, 검출률 10.8%) 함유되어 있었다. 또한 비알콜성음료에 함유된 인공감미료 중 아스파탐은 Min Extreme 분포, 아세설팜칼륨은 Logistic 분포, 수크랄로스는 Student"s t 분포를 나타냈다. 비알콜성음료 섭취량은 어린이와 청소년 전체를 대상으로 한 시나리오Ⅰ에서는 대부분 Logistic 분포를 나타내었으나, 특히 소비자집단만을 고려한 시나리오Ⅱ 경우에는 왼쪽으로 기울어진 Max Extreme 분포가 되었다. 체중은 시나리오Ⅰ이 Logistic 분포, 시나리오Ⅱ는 Beta 분포를 나타내었다. 그리고 시나리오Ⅰ에서 확률평가한 아스파탐, 아세설팜칼륨, 수크랄로스의 평균 추정식이섭취량은 각각 0.09, 0.01, 0.04mg/kg bw/day였으며, 95th percentile 추정식이섭취량은 각각 0.30, 0.02, 0.13 mg/kg bw/day였다. 확률평가한 아스파탐, 아세설팜칼륨, 수크랄로스의 평균 %ADI는 각각 0.22, 0.04, 0.24이었고, 확률평가한 95th percentile %ADI는 각각 0.75, 0.13, 0.83으로 안전한 수준이었다. 시나리오 Ⅱ에서 확률평가한 아스파탐, 아세설팜칼륨, 수크랄로스의 평균 추정식이섭취량은 각각 0.52, 0.03, 0.22 mg/kg bw/day였으며, 95th percentile 추정식이섭취량은 각각 1.80, 0.12, 0.75 mg/kg bw/day였다. 확률평가한 아스파탐, 아세설팜칼륨, 수크랄로스의 평균 %ADI는 각각 1.32, 0.22, 1.44였고, 확률평가한 95th percentile %ADI는 4.52, 0.80, 5.06으로 나타났다. 즉 비알콜성음료 섭취를 통한 인공감미료 중 아스파탐, 아세설팜칼륨, 수크랄로스의 노출수준은 일일섭취허용량(ADI)을 초과하는 인구집단은 없는 것으로 나타났으며, 시나리오 Ⅰ?Ⅱ에서 아스파탐, 아세설팜칼륨, 수크랄로스의 평균 및 95th percentile %ADI는 모두 5.06이내로 낮은 수준이었다. 한편 섭취자군 중 인공감미료에서 검출률이 가장 높았던 수크랄로스의 경우 %ADI가 10 이상일 확률이 2.2%였다. The aims of this study were to estimate daily intakes of artificial sweeteners from beverages and liquid teas as well as evaluate their potential health risks in Korean children and adolescents (1 to 19 years old). Dietary intake assessment was conducted using actual levels of aspartame, acesulfame-K, and sucralose in non-alcoholic beverages (651 beverages and 87 liquid teas), and food consumption amounts were drawn from "The Fourth Korea National Health and Nutrition Examination Survey (2007~2009)". To estimate dietary intake of non-alcoholic beverages, a total of 6,082 children and adolescents (Scenario Ⅰ) were compared to 1,704 non-alcoholic beverage consumption subjects (Scenario Ⅱ). The estimated daily intake of artificial sweeteners was calculated based on point estimates and probabilistic estimates. The values of probabilistic artificial sweeteners intakes were presented by a Monte Carlo approach considering probabilistic density functions of variables. The level of safety for artificial sweeteners was evaluated by comparisons with acceptable daily intakes (ADI) of aspartame (0~40 mg/kg bw/day), acesulfame-K (0~15 mg/kg bw/day), and sucralose (0~15 mg/kg bw/day) set by the World Health Organization. For total children and adolescents (Scenario Ⅰ), mean daily intakes of aspartame, acesulfame-K, and sucralose estimated by probabilistic estimates using Monte Carlo simulation were 0.09, 0.01, and 0.04 mg/kg bw/day, respectively, and 95th percentile daily intakes were 0.30, 0.02, and 0.13 mg/kg bw/day, respectively. For consumers-only (Scenario Ⅱ), mean daily intakes of aspartame, acesulfame-K, and sucralose estimated by probabilistic estimates using Monte Carlo simulation were 0.52, 0.03, and 0.22 mg/kg bw/day, respectively, and 95th percentile daily intakes were 1.80, 0.12, and 0.75 mg/kg bw/day, respectively. For scenarios Ⅰ and Ⅱ, neither aspartame, acesulfame-K, nor sucralose had a mean and 95th percentile intake that exceeded 5.06% of ADI.

Estimation of daily curcuminoid intake from commercial curry products

Kim, Young-Jun,Lee, Hyong Joo,Shin, Youngjae 한국응용생명화학회 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.5

Turmeric, the main spice in curry, contains curcuminoids, which have been closely linked to the prevention of various chronic diseases. However, the daily intake of curcuminoids from curry consumption remains unclear. This study optimized an analytical method for quantifying individual curcuminoids and then applied it to 50 commercial curry samples available in the retail market. The curcuminoids namely curcumin, demethoxycurcumin, and bisdemethoxycurcumin, which provide the yellow color present in turmeric, were analyzed, and a daily curcuminoid intake from a curry-based diet was estimated. Prior to data collection, the analytical method, incorporating high-performance liquid chromatography with a diode array detector, was validated for linearity, limit of detection (0.03-0.04 mg/kg), limit of quantification (0.10-0.14 mg/kg), and precision and accuracy (less than a relative standard deviation of 1.25 %). Total curcuminoid content in the curry products tested varied greatly depending on the product type, ranging from 24.59 to 161.02 mg/100 g (mean 75.92 mg/100 g) for powdered curry and from 1.04 to 10.78 mg/100 g (mean 4.12 mg/100 g) for retorted curry (precooked curry packaged in a retorted pouch). The daily intake of total curcuminoids from curry products, estimated from the data in this study and available domestic consumption data, was 0.339 mg/person/day for males and 0.299 mg/person/day for females. The distribution of total curcuminoids varied greatly by product owing to variation in the turmeric contents used by curry manufacturers in individual products. The results reveal the wide variation in the curcuminoid contents of commercial curry products and provide information on daily curcuminoid intake.

Estimation of daily curcuminoid intake from commercial curry products

김영준,이형주,신영재 한국응용생명화학회 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.5

Turmeric, the main spice in curry, contains curcuminoids, which have been closely linked to the prevention of various chronic diseases. However, the daily intake of curcuminoids from curry consumption remains unclear. This study optimized an analytical method for quantifying individual curcuminoids and then applied it to 50 commercial curry samples available in the retail market. The curcuminoids namely curcumin, demethoxycurcumin, and bisdemethoxycurcumin, which provide the yellow color present in turmeric, were analyzed, and a daily curcuminoid intake from a curry-based diet was estimated. Prior to data collection, the analytical method, incorporating high-performance liquid chromatography with a diode array detector, was validated for linearity, limit of detection (0.03–0.04 mg/kg), limit of quantification (0.10–0.14 mg/kg), and precision and accuracy (less than a relative standard deviation of 1.25 %). Total curcuminoid content in the curry products tested varied greatly depending on the product type, ranging from 24.59 to 161.02 mg/100 g (mean 75.92 mg/100 g) for powdered curry and from 1.04 to 10.78 mg/100 g (mean 4.12 mg/ 100 g) for retorted curry (precooked curry packaged in a retorted pouch). The daily intake of total curcuminoids from curry products, estimated from the data in this study and available domestic consumption data, was 0.339 mg/ person/day for males and 0.299 mg/person/day for females. The distribution of total curcuminoids varied greatly by product owing to variation in the turmeric contents used by curry manufacturers in individual products. The results reveal the wide variation in the curcuminoid contents of commercial curry products and provide information on daily curcuminoid intake.

식품군별 섭취중량 변화에 따른 납의 경구섭취 추정량의 경년변화

문찬석,Moon, Chan-Seok 한국환경보건학회 2011 한국환경보건학회지 Vol.37 No.4

Objectives: The aim of this study is to examine the possible changes over the past ten years in the estimated daily dietary lead intake (Pb-D) stemming from the variation of daily intake amounts for each food group. The following factors were considered; 1. time trends in Pb-D as the estimated values, 2. the time trend in Pb-D by food groups 3. the most influential food groups for dietary Pb intake. Methods: Estimated Pb-D was drawn from food consumption according to food groups reported in the Korean National Health and Nutrition Survey and the lead contents of each food group as reported in 23 prior publications. Results: The estimated Pb-D in a 2009 survey was 40.8 ${\mu}g/day$, of which 22.5 ${\mu}g/day$ (55.1%) was of plant origin and 18.3 ${\mu}g/day$ (44.9%) was of animal origin. Meats and poultry, fish and shellfish among foods of animal origin and beverages of plant origin had the largest contribution in Pb-D among the food groups. Conclusion: Over past ten years, daily lead intakes have slightly increased among men. Otherwise, no clear variation is apparent among women.

영양의 불균형과 노화에 관한 연구

박윤진 淸州大學校 學術硏究所 2006 淸大學術論集 Vol.7 No.-

The purpose of this study is to get the problem of nutritional unbalance and aging in modem living not only obesity by over-intake but also low-weight disease by nutritional control and social function in which cause to starvation condition and environment cause of inherent, posteriori disease which to prevent this disease and aging to gain material of life-long healthy that the results from this study are as follows. To continue adequate intake condition and to contain fuel(especially fat) starvation condition not consume all of them which nutritional unbalance contain fat into obesity. After 2000 years revealed marvelously low-weight, low-birth, low-bone density, low-rice consume statement by starvation excellently to risk healthy of women and children. We need to applicate for prevent of disease and aging that to resolve the nutritional unbalance and starvation according to universal food life change consist of (Estimated Average Requirement, EAR), (Recommended Intake, RI), (Adequate Intake, AI), (Tolerable Upper Intake Level, UL), to decide (Dietary Reference Intakes; DRIs) in korean nutrition recommended intake. Aging was expected one of them expect-change which change of obesity-feed cycle and exercise cycle that this time shows to decrease sense density about hormone of main organization in body, as a result of starvation-feed cycle transfer organization normal reaction decrease ability. Aging is decide to factor limited age of people that relate to aging of man and the old disease. Aging and exercise metabolism statement is in decrease nutrition, hormone shows in metabolic organization as metabolic corelation among organization.

EFFECT OF OVER-EXPANSION CYCLE IN A SPARK-IGNITION ENGINE USING LATE-CLOSING OF INTAKE VALVE AND ITS THERMODYNAMIC CONSIDERATION OF THE MECHANISM

Shiga, S.,Hirooka, Y.,Miyashita, Y.,Yagi, S.,Machacon, H.T.C.,Karasawa, T.,Nakamura, H. The Korean Society of Automotive Engineers 2001 International journal of automotive technology Vol.2 No.1

This paper presents further investigation into the effect of over-expansion cycle in a spark-ignition engine. On the basis of the results obtained in previous studies, several combinations of late-closing (LC) of intake valve and expansion ratio were tested using a single-cylinder production engine. A large volume of intake capacity was inserted into the intake manifold to simulate multi-cylinder engines. With the large capacity volume, LC can decrease the pumping loss and then increase the mechanical efficiency. Increasing the expansion ratio from 11 to 23.9 with LC application can produce about 13% improvement of thermal efficiency which was suggested to be caused by the increased cycle efficiency. The decrease of compression ratio from 11 to 5.5 gives little effect on the thermal efficiency if the expansion ratio could be kept constant. Thus, the expansion ratio is revealed to be a determining factor for cycle efficiency, while compression ratio is no more important, which suggests the usefulness of controlling the intake charge with intake valve closure timing. These were successfully explained by simple thermodynamic calculation and thus the mechanism could be verified by the estimation.