• Title/Summary/Keyword: Germanium

Search Result 332, Processing Time 0.035 seconds

Development of a Synthetic Method for [68Ga]Ga-FAPI-04 Using a Cassette-based Synthesizer (카세트 기반 자동합성장치를 사용한 [68Ga]Ga-FAPI-04의 합성방법 연구)

  • Jun Young PARK;Won Jun KANG
    • Korean Journal of Clinical Laboratory Science
    • /
    • v.56 no.1
    • /
    • pp.43-51
    • /
    • 2024
  • [68Ga]Ga-FAPI-04 is a promising radiopharmaceutical that binds specifically to fibroblast activation protein, which is overexpressed in more than 90% of malignant epithelial tumors but not in normal healthy tissue. This study aimed to develop an efficient method for producing 68Ga-labelled FAPI-04 using a cassette-based automated synthesizer. [68Ga]GaCl3 was eluted from an Eckert & Ziegler Medical germanium-68/gallium-68 generator using 2.5 mL of 0.1 M HCl. The synthesis of the [68Ga]Ga-FAPI-04 was performed using different concentrations of HEPES (1~2.5 M; 4-(2-hydroxyethyl) piperazine-1-ethanesulfonic acid) in 3~10 minutes; amounts of FAPI-04 precursor (5~50 ㎍) and reaction temperature (25℃~100℃) were optimized on the BIKBox® synthesizer. The labeling efficiency of [68Ga]Ga-FAPI-04 was greater than 96% (decay corrected) using 25 ㎍ FAPI-04 synthesized in 10 minutes at 100℃ in 2 M HEPES (pH 3.85), and its stability was greater than 99% at 6 hours. The total synthesis time of [68Ga]Ga-FAPI-04 was 32.4 minutes, and the product met all quality control criteria. In this study, we developed and optimized a labeling method using [68Ga]Ga-FAPI-04 using a cassette-based synthesizer. The devised method is expected to be useful for supplying [68Ga]Ga-FAPI-04 for diagnosis in clinical practice.

Multivariate statistical study on naturally occurring radioactive materials and radiation hazards in lakes around a Chinese petroleum industrial area

  • Yan Shi;Junfeng Zhao;Baiyao Ding;Yue Zhang;Zhigang Li;Mohsen M.M.Ali;Tuya Siqin;Hongtao Zhao;Yongjun Liu;Weiguo Jiang;Peng Wu
    • Nuclear Engineering and Technology
    • /
    • v.56 no.6
    • /
    • pp.2182-2189
    • /
    • 2024
  • The high-purity germanium gamma-ray spectrometer was used to measure the radioisotope in surface water of lakes in a Chinee petroleum industrial area. 92 samples were collected from surface water of three lakes. Activity concentrations of 232Th, 226Ra and 40K in three lakes were measured, distributed in the range of 101.8-209.4, 192.1-224.9 and 335.0-548.9 mBq/L, respectively. Results were all within the limits of WHO and China. Potential environmental and health risks were assessed by calculating some radiation hazard indicators, radium equivalent index, annual effective dose, excess lifetime cancer risk, absorbed dose rate, external hazard index, internal hazard index, annual gonadal dose equivalent, activity utilization index and representative gamma index, which ranged 0.38-0.54 Bq/L, 0.06-0.08 mSv/y, 0.23 × 10-3-0.31 × 10-3, 0.17-0.24 nGy/h, 1.01 × 10-3-1.46 × 10-3, 1.55 × 10-3-2.02 × 10-3, 1.16-1.66 μSv/y, 3.13 × 10-3-4.45 × 10-3 and 2.60 × 10-3-3.77 × 10-3. The results were all at acceptable levels, meaning no impact on human health. The relationship between the electrical conductivity of surface water and the activity concentration of 232Th, 226Ra and 40K was evaluated. The electrical conductivity value was 0.241-0.369 mS/cm, showing a significant correlation coefficient between 226Ra and 40K and electrical conductivity. Multivariate statistical methods were used to determine the relationship between the activity concentrations of 232Th, 226Ra, and 40K, radiation hazard indicators and electrical conductivity.

Effects of $GeO_2$ and Citric Acid on Germanium Content of Callus and Plant in Angelica koreana MAX (강활(羌活)의 캘러스 및 식물체(植物體) 중(中) Ge함량(含量)에 미치는 $GeO_2$와 Citric Acid의 영향(影響))

  • Park, Byoung-Woo;Lee, Joong-Ho;Kwon, Tae-Oh
    • Korean Journal of Medicinal Crop Science
    • /
    • v.4 no.2
    • /
    • pp.101-108
    • /
    • 1996
  • This study was conducted to investigate the effect of growth regulators and $GeO_2$ on the induction and proliferation of callus and the effect of $GeO_2$ and citric acid on the Ge content of callus from explants and plant, Angelica koreana Max. The results obtained were summarized as follows. The callus induction was most effective on MS (Murashige and Skoog) medium containing 1. 0ppm 2, 4 - D with petiolule. The proliferation of callus was most effective at 2. 0ppm 2, 4 - D on the medium, at 2. 5ppm $GeO_2$ on the medium containing 2. 0ppm 2, 4 - D, and at $0.\;1{\sim}1mM$citric acid on the medium at pH6 containing 2. 0ppm 2, 4 - D and 2. 5ppm $GeO_2.$ The more $GeO_2$ in MS medium up to 20ppm, the more Ge content in callus. Ge content in callus was highest when the medium was supplemented with 0. 1mM citric acid and the pH of medium was low. The Ge content in plant was high in order of leaf > root > stem. Application $GeO_2$ to the soil increased Ge content in plant and application of 1mM citric acid with $GeO_2$ resulted in increasing Ge content highest in plant, but application more than l0mM citric acid resulted in Ge content decreased. Application of $GeO_2$ increased Ge content in callus and plant but had a tendency to decrease some mineral content, on the other hand application of $0.\;1{\sim}1mM$ citric acid with $GeO_2$ had a tendency to increase mineral content.

  • PDF

Metal 첨가물질에 따른 비정질 IGZO 투명전극 특성 연구

  • Sin, Han-Jae;Hwang, Do-Yeon;Lee, Jeong-Hwan;Lee, Dong-Ik;Park, Seong-Eun;Park, Jae-Seong;Kim, Seong-Jin;Lee, Yeong-Ju;Seo, Chang-Taek
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2013.02a
    • /
    • pp.368-370
    • /
    • 2013
  • 투명 전극은 전기전도도를 갖는 동시에 가시광선을 투과하는 소재를 말하며, 구체적으로는 빛의 파장이 400~700 nm 영역대의 가시광선을 80% 이상 투과하며 전기전도도가 비저항으로 $10^{-3}{\Omega}cm$이하이거나 면저항이 $10^3{\Omega}$/${\Box}$소재를 의미한다. 투명 전극은 전기전도도에 따라 사용되는 용도가 다양하다. LCD, PDP, OLED 와 같은 평판디스플레이 및 3D 디스플레이의 투명전극으로 사용되는 핵심재료일 뿐만 아니라 터치스크린, 투명필름, 대전방지막, 열반사막, EMI 방지막, 태양전지 분야에 광범위하게 이용되고 있다. 일반적으로, 투명전극 박막에 가장 많이 사용되고 있는 소재는 ITO (indium tin oxide)이나, 주성분인 In의 사용량 증가로 상용 ITO 타겟 가격이 급등하고 있음으며, 고가의 ITO 타겟을 대체하기 위한 저가의 투명전극 소재 개발이 절대적으로 요구되며, 신규 소재 개발을 통한 기술력 우위 선점이 필수적으로 요구되는 상황이다. 본 연구에서는 기존에 디스플레이 분야에서 널리 활용되는 고가의 ITO를 대체하기 위한 다성분 금속산화물 투명전극 스퍼터링 타겟 제조기술을 개발하기 위한 연구로서, Metal이 첨가된 In-Ga-Zn-O기반의 3성분계 투명도전성 소재를 조성설계, 고밀도 균질 타겟 제조 및 투명전극 박막을 형성하는 연구를 실시하였다. 고체산화물 산화인듐(In2O3)분말, 산화갈륨(Ga2O3) 분말그리고 산화아연(ZnO)분말과 Metal을 몰비로 칭량한 후 분말을 폴리에틸렌제 포트에 넣고 에탄올을 충분히 채운 후 지르코니아(ZrO2) 볼(ball)을 이용하여 24 h 동안 볼 밀링(ball milling) 방법으로 혼합한 뒤, $120^{\circ}C$의 플레이트위에서 마그네틱 바로 stirring하면서 건조하였다. 이 분말을 건조기에서 완전히 건조한 후 알루미나 유발을 이용해서 pulverizing한 후 sieving기를 이용하여 분말의 조립화를 하였다. 이 분말을 금형에 넣고 300 kg/$cm^2$의 압력으로 press하여 성형한 뒤 대기중에서 소결하였다 소결을 위한 승온 온도는 $10^{\circ}C$/min이었고 소결은 $1,450^{\circ}C$에서 6 h 동안 하였다. IGZO target의 조성 비율은 1:1:12 (mol%)를 사용하였으며, 첨가한 Metal은 Boron (B), Germanium (Ge), Barium (Ba)을 사용하여 타겟을 제작하였다. M-IGZO 박막은RF magnetron Sputter를 이용하여 증착하였으며, 앞선 실험에서 제작한 타겟을 사용하여 M-IGZO박막을 투명전극으로 사용하기 위한 각각의 특성을 파악하였다. 모든 박막은 상온에서 증착을 하였으며, 증착된 박막두께를 측정하기 위해 ${\alpha}$-step IQ를 사용하였고, 광학적 특성을 분석하기 위해 UV-Visible spectrophotometer 로 투과율을 측정하였다. 그리고 전기적 특성을 측정하기 위해 Hall effect measurement 및 4-probe를 사용하였으며, 결정성 분석을 위하여 XRD를 이용하여 분석하였다. 표1은 M-IGZO타겟을 사용하여 증착시간에 따른 면저항 특성을 나타내었다. Ge, B, Ba이 첨가된 IGZO 박막은 증착시간이 증가할수록 면저항이 낮아짐을 알 수 있었다. 또한, Ge이 첨가된 IGZO 박막이 다른 금속이 첨가된 IGZO 박막의 면저항보다 현저히 낮음을 알 수 있었다. Fig. 1(a), (b), (c)는 각 타겟을 동일한 조건으로 증착을 하여 광학적특성을 나타내는 그래프이다. GZO 박막의 광학적 특성을 보면 가시광 영역에서 평균 투과율은 모두 80% 이상으로 우수한 광투과 특성을 보여 투명전자소자로 사용가능하다. 특히, 자외선 영역을 모두 차단하는 UV cut 능력이 우수함을 알 수 있었다. 따라서, 금속이 첨가된 IGZO 박막을 태양전지용 투명전극으로 사용할 경우, 자외선에 의하여 수명이 단축되는 현상을 줄여줄 수 있음을 기대할 수 있으며 내구성 향상에 크게 기여할 것으로 보인다. Fig. 2는 Ge=0, 0.5, 5%인 IGZO 투명전극을 총 40회 반복하여 증착을 실시한 후 각각의 면저항을 측정한 결과이다. 실험결과에 따르면 Ge가 0%, 5%인 IGZO 투명전극은 증착을 거듭할수록 면저항이 증가하는 결과를 나타내었으며, 0.5%인 IGZO 투명전극은 점차 안정화되어가는 결과를 나타내었다. 따라서 안정화 되었을 때 평균 면저항은 26ohm/sq.로 나타났으며, 광투과율은 Fig. 3과 같이 가시광영역에서 평균 80%이상의 결과를 보였으며, 550 nm에서는 86.36%의 우수한 특성을 나타내었다. 본 연구에서는 Metal이 첨가된 In-Ga-Zn-O기반의 3성분계 투명도전성 소재 target을 제작하여 RF magnetron sputter로 박막을 형성한 후 특성을 비교하였다. M-IGZO target 중 Ge (0.5%)을 첨가한 IGZO 타겟을 사용한 투명전극이 가장 우수한 특성을 보였으며, 제작된 M-target의 In 비율이 30% 정도로 기존의 ITO (90%) 대비하여 투명전극 제작 단가를 절감할 수 있다.

  • PDF

Cooling Time Determination of Spent Nuclear Fuel by Detection of Activity Ratio $^{l44}Ce /^{l37}Cs$ (방사능비 $^{l44}Ce /^{l37}Cs$ 검출에 의한 사용후핵연료 냉각기간 결정)

  • Lee, Young-Gil;Eom, Sung-Ho;Ro, Seung-Gy
    • Nuclear Engineering and Technology
    • /
    • v.25 no.2
    • /
    • pp.237-247
    • /
    • 1993
  • Activity ratio of two radioactive primary fission products which had sufficiently different half-lives was expressed as functions of cooling time and irradiation histories in which average burnup, irradiation time, cycle interval time and the dominant fissile material of the spent fuel were included. The gamma-ray spectra of 36 samples from 6 spent PWR fuel assemblies irradiated in Kori unit-1 reactor were obtained by a spectrometric system equipped with a high purity germanium gamma-ray detector. Activity ratio $^{l44}$Ce $^{l37}$Cs, analyzed from each spectrum, was used for the calculation of cooling time. The results show that the radioactive fission products $^{l44}$Ce and $^{l37}$Cs are considered as useful monitors for cooling time determination because the estimated cooling time by detection of activity ratio $^{l44}$Ce $^{l37}$Cs agreed well with the operator declared cooling time within relative difference of $\pm$5 % despite the low counting rate of the gamma-ray of $^{l44}$Ce (about 10$^{-3}$ count per second). For the samples with several different irradiation histories, the determined cooling time by modeled irradiation history showed good agreement with that by known irradiation history within time difference of $\pm$0.5 year. From this result, it would be expected to be possible to estimate reliably the cooling time of spent nuclear fuel without the exact information about irradiation history. The feasibility study on identification of and/or sorting out spent nuclear fuel by applying the technique for cooling time determination was also performed and the result shows that the detection of activity ratio $^{l44}$Ce $^{l37}$Cs by gamma-ray spectrometry would be usefully applicable to certify spent nuclear fuel for the purpose of safeguards and management in a facility in which the samples dismantled or cut from spent fuel assemblies are treated, such as the post irradiation examination facility.mination facility.

  • PDF

Measurement of Environmental Radiation Using Medical Scintillation Detector in Well Counter System (의료용 우물형 섬광계수기를 이용한 환경 방사선 측정)

  • Lyu, Kwang Yeul;Park, Yeon-joon;Kim, Min-jeong;Ham, Eun-hye;Yoon, Ji-yeol;Kim, Hyun-jin;Min, Jung Hwan;Park, Hoon-Hee
    • Journal of radiological science and technology
    • /
    • v.38 no.4
    • /
    • pp.337-345
    • /
    • 2015
  • After the Fukushima nuclear accident in 2011, concerns about radiation by people are increasing rapidly. If people could know how much they will be exposed by radiation, it may help them avoiding it and understand what exactly radiation is. By doing this, we were helping to reduce the anxiety of radiation contamination. In this study, we have researched figures of radioactivity with 'Captus-3000 thyroid uptake measurement systems' in well counter detector system. The materials were measured with Briquette, Shiitake, Pollock, Button type battery, Alkaline battery, Topsoil, Asphalt, Gasoline, Milk powder, Pine, Basalt stone, Pencil lead, Wasabi, Coarse salt, Tuna(can) Cigar, Beer, and then we categorized those samples into Land resources, Water resources, Foodstuff and Etc (Beer classified as a water resources has been categorized into Foodstuff). Also, we selected the standard radiation source linear 137Cs to measure the sensitivity of well counter detector. After that, we took cpm(counter per minute) for the well counter detector of thyroid uptake system's sensitivity. Then we compared the results of each material's cpm and converted those results to Bq/kg unit. There were a little limitation with the measurement equipment because it has less sensitivity than other professional equipment like 'High purity germanium radiation detector'. Moreover, We didn't have many choices to decide the materials. As a result, there are macroscopic differences among the rates of material's spectrum. Therefore, it had meaningful results that showed how much each material had emitted radiation. To compare the material's cpm with BKG, we've compounded their spectrums. By doing that, we were able to detect some differences among the spectrums at specific peak section. Lastly, Button type battery, Alkaline Battery, Briquette, Asphalt and Topsoil showed high value. There were classified emitting high radiation Group A and emitted lower radiation Group B. The Group A, alkaline battery showed higher rate of radiation by 7.67 %, and Button type battery was yield 4.65 % higher rate than BKG. Additionally, Asphalt (8.03 %), Topsoil (3.76 %), Briquette (7.46 %) were yield for higher values. Several samples of the daily supplies were yield little higher, but it seems safe to use in daily lives. In the case of the 'Foodstuff', all of the samples were safe and they were under the radiation limits of the Ministry of Food and Drug Safety for Food; thus, we highly recommend this study to you as a reference of common daily routine.

Radium Isotope Ratio as a Tracer for Estimating the Influence of Changjiang Outflow to the Northern Part of the East China Sea (라듐 동위원소 방사능비를 추적자로 사용한 동중국해 북부 해역에서 장강 유출수의 영향 추정)

  • Kim, Kee-Hyun;Kim, Seung-Soo
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.12 no.3
    • /
    • pp.133-142
    • /
    • 2009
  • In order to understand the present environmental condition and future impingement of Changjiang(Yangtze River) outflow upon the adjacent seas after the scheduled completion of the Sanxia (Three Gorges) Dam in 2009, we tried to estimate the mixing ratios among surface waters of three end-members: Changjiang Water (CW), Kuroshio Water (KW), and East China Sea Water (ECSW) using $^{228}Ra/^{226}Ra$ activity ratio and salinity as tracers. Water samples were collected from 32 stations in November 2005 (R/V Tamgu 3), from 20 stations in July 2006 (R/V Ocean 2000) and from 17 stations in August 2006 (R/V Ieodo) in the northern part of the East China Sea. Radium isotopes in ~300 liters of surface seawater were extracted onboard by filtering through manganese impregnated acrylic fibers and following coprecipitation as $Ba(Ra)SO_4$. Activities of radium isotopes were determined by a high purity germanium detector. Results show that the fraction of CW was in the range of 1-23% in the study area, while KW was in the range of 0-30 % and ECSW 58-100 %. The eastward plume of Changjiang outflow, commonly observed in satellite images during summer and also displayed by the eastward-decreasing CW fraction in this study, could be attributed to Ekman transport caused by the SE monsoon prevailing in this region during summer. Results of this study showed that in the drought season, there was a little or no fraction of CW in the study area. Concentration of dissolved inorganic nitrogen (DIN) showed strong positive relationship with the fraction of CW, suggesting Changjiang as the major source of nitrogen. The mixing curve of DIN indicates the removal of nitrate by biological uptake during the mixing of CW with ambient seawater in the study area.

  • PDF

Distribution of natural radionuclide in the Geum river sediment (금강수계 퇴적물 중 천연 방사성핵종 분포 조사)

  • Seol, Bitna;Cho, Yoonhae;Min, Kyungok;Kim, Wansuk;Oh, Dayeon;Kil, Gibeom;Yang, Yunmo;Lee, Junbae;Kim, Byungik;Cheon, Seok
    • Analytical Science and Technology
    • /
    • v.30 no.5
    • /
    • pp.262-269
    • /
    • 2017
  • The concentration of natural radioactivity in the sediment of the Geum River was investigated. The river and lake sediment samples were collected at 23 points during September to November, 2015 and March to April, 2015, respectively. The gamma-rays emitted from the $^{226}Ra$ and $^{232}Th$ decay series and $^{40}K$ were measured with a high purity germanium (HPGe) gamma detector. The average radioactivity concentrations of the $^{226}Ra$, $^{232}Th$ decay series and $^{40}K$ for the river sediment was found to be $15.6{\pm}0.6$, $33.8{\pm}1.2$, $789.8{\pm}26.0Bq/kg$, respectively, while for the lake sediment, the concentrations were $17.1{\pm}0.5$, $37.8{\pm}1.1$, $269.4{\pm}9.6Bq/kg$, respectively. Spearman's correlation was conducted to compare the radioactivity concentration and properties of the sediment. The radioactivity concentration of the $^{232}Th$ decay series showed a negative correlation with the particle size of the sediment, and was measured to be higher than the $^{226}Ra$ decay series according to mobility of the radionuclides. The radioactivity concentration of $^{40}K$ showed a negative correlation with organic matter content. The concentration of $^{40}K$ in the lake sediment was lower than that in the river sediment.

Neuroprotective effects of Extract of Broccoli, Cultivated in Desalinated Magma Seawater, on neuron-like SH-SY5Y cells (제주도 탈염 용암해수 재배로 제조한 브로콜리 추출물의 신경 세포 보호 효과)

  • Rhee, Jin Seol;Jang, Youn Bi;Choi, Ge Sun;Choung, Jai Jun;Kang, Seung Woo
    • Journal of the Korean Applied Science and Technology
    • /
    • v.37 no.3
    • /
    • pp.448-462
    • /
    • 2020
  • Dietary nutrition is a critical lifestyle factor that can reduce the risk of future cognitive impairments caused by dementia. Accumulating evidence suggests that dietary supplementation with Sulforaphane may help the prevention of cognitive impairments and dementia. Thus, Sulforaphane-enriched broccoli extract would hold promise to improve cognitive impairments of dementia patients. Here, we have used broccoli extracts, prepared from broccoli cultivated in Magma Seawater, to test if the broccoli extracts can be dietary supplement to improve cognitive impairments. Magma Seawater originated from Jeju Island, Korea is unique in terms of containing high concentrations of usable minerals (Zinc, Vanadium and Germanium etc.). Broccoli, grown in Magma Seawater, would contain Sulforaphane and the extra amount of usable minerals. The chemical compositions of the broccoli extracts were analyzed using LC-Q-orbitrap to detect Sulforaphane and Glucoraphanin. Analysis method based on HPLC was developed for measurement of sulforaphane levels in the broccoli extracts. We have tested if the broccoli extracts have anti-apoptotic and anti-inflammatory effects on neuron-like SH-SY5Y cells. In addition, we examined if the broccoli extracts are able to upregulate expression of synaptic plasticity-associated proteins (BDNF and phospho-CREB) and to inhibit acetylcholine esterase (AchE) activity. We have shown that the broccoli extracts inhibited the apoptotic pathway and inflammatory responses. Finally, we present evidence showing that AchE activity was inhibited by the broccoli extracts, but expression of BDNF and phospho-CREB was upregulated. Taken together, these findings suggest that the broccoli extracts from Magma Seawater-grown broccoli would be a good source of dietary nutrition to improve cognitive impairments in the future.

Physicochemical Properties of Shinan Seomcho(Spinacia olerecea L.) (신안 섬초(시금치)의 이화학적 특성)

  • Na, Hwan-Sik;Kim, Jin-Young;Mun, Hee;Choi, Gyeong-Cheol;Jeong, Seon-Ho;Cho, Jeong-Young;Ma, Seung-Jin
    • Food Science and Preservation
    • /
    • v.17 no.5
    • /
    • pp.652-658
    • /
    • 2010
  • This study was to investigate physicochemical properties of Shinan seomcho growing in Jeollanamdo. The samples used were Shinan seomcho(Josaeng, Mansaeng varieties), Pohangcho(Josaeng, Mansaeng varieties), Namhaecho (Josaeng, Mansaeng varieties) and greenhouse spinach(Josaeng varieties). The results were as follows ; The thickness of spinach leaves were contained in order of Shinan seomcho > Pohangcho > Namhaecho > greenhouse spinach, and the hardness of those were contained in order of Pohangcho > Namhaecho > Shinan seomcho > greenhouse spinach. In Hunter's color value, L, a, b value in greenhouse spinach was lower than those of the others. Among the spinach varieties, Josaeng-jong(3.39~5.38 mg%) had the highest level of total dietary fiber contents than that of Mansaeng-jong(2.94~3.91 mg%). By regional groups, total dietary fiber were contained in order of Pohangcho > Namhaecho > Shinan seomcho > greenhouse spinach. The free sugar contents in the sample group, Shinan seomcho(4 varieties), Pohangcho(1 variety) and Namhaecho(2 varieties) were higher than those of other spinach varieties. The total sugar contents in the sample group, Shinan seomcho(3 varieties), Pohangcho(1 variety) and Namhaecho(2 varieties) were higher than those of other spinach varieties. Total flavonoid contents of Shinan seomcho(Josaeng-jong) and Namhaecho(Josaeng-jong) were lower than 130 mg%, but the other spinach had more than 130 mg% of total flavonoid contents. Germanium contents were detected in the following order ; Shinan seomcho(47.46 ${\mu}g$/kg) > Namhaecho(30.13 ${\mu}g$/kg) > Pohangcho(26.39 ${\mu}g$/kg) > greenhouse spinach(25.32 ${\mu}g$/kg).