The surge in food delivery systems during the coronavirus 2019 pandemic necessitated this study of heavy metal migration from food contact materials (FCMs). A total of 104 samples of FCMs, comprising 51 polypropylene (PP), 21 polyethylene (PE), and 32 polystyrene (PS) samples of six different types of FCMs (containers, covers, table utensils, cups, pouches, and wrappers) used for food delivery distributed in Korea, were collected and investigated for migration of three heavy metals (Pb, Cd, and As) using inductively coupled plasma–mass spectrometry (ICP-MS) to determine whether they complied with Korea’s Standards and Specifications for Utensils, Containers, and Packages. Acetic acid (4%, v/v) was used as the food simulant, and tests were performed at 100oC (in harsh conditions) for 30 min. Linearity of Pb, Cd, and As showed acceptable results with a coefficient of determination (R2) value of 0.9999. Limit of detection (LOD) and limit of quantification (LOQ) of Pb, Cd, and As were 0.001, 0.001, and 0.001 μg/L and 0.002, 0.003, and 0.003 μg/L, respectively. Accuracy and precision results complied with the criteria presented in the European Commission Joint Research Centre guidelines. The average concentration of Pb, Cd, and As migration detected in a total of 104 samples was 0.009–0.260 μg/L, which was very low compared with the migration specification set in the Standards and Specifications for Utensils, Containers, and Packages. The maximum level of Pb corresponded to 0.23% of the migration limit. There were no samples exceeding the limit. Thus, this study confirmed that the heavy metal contents of FCMs used for delivery food distributed in Korea were safely managed. The data from this study represent an invaluable source for science-based safety management of hazardous heavy metals migrating from FCMs used in the food delivery industry.

Boron nitride nanotubes (BNNTs) are receiving great attention because of their unusual material properties, such as high thermal conductivity, mechanical strength, and electrical resistance. However, high-throughput and highefficiency synthesis of BNNTs has been hindered due to the high boiling point of boron (~ 4000℃) and weak interaction between boron and nitrogen. Although, hydrogen-catalyzed plasma synthesis has shown potential for scalable synthesis of BNNTs, the direct use of H2 gas as a precursor material is not strongly recommended, as it is extremely flammable. In the present study, BNNTs have been synthesized using radio-frequency inductively coupled thermal plasma (RF-ITP) catalyzed by solid-state ammonium chloride (NH4Cl), a safe catalyst materials for BNNT synthesis. Similar to BNNTs synthesized from h-BN (hexagonal boron nitride) + H2, successful fabrication of BNNTs synthesized from h-BN+NH4Cl is confirmed by their sheet-like properties, FE-SEM images, and XRD analysis. In addition, improved dispersion properties in aqueous solution are found in BNNTs synthesized from h-BN +NH4Cl.

The analytical method for the determination of phosphorus in foods was validated by inductively coupled plasma optical emission spectrometry (ICP-OES) in terms of precision, accuracy, recovery efficiency and linearity. Regression analysis revealed good correlation coefficient, higher than 0.999. Recovery efficiencies of the minerals ranged from 90.36% to 110.63%, and the limit of detection (LOD) and the limit of quantification (LOQ) were 0.0745 mg/ kg and 0.2482 mg/kg, respectively. The value of inter-day and intra-day ranged from 1.43 to 3.23% and from 0.40 to 1.77%. The recovery efficiencies ranged from 97.8 to 110.6%. The method was also compared with Molybdenum blue colorimetric method using certified and statistically significant difference was also not observed in the between two different analytical methods. The ICP-OES method was applied to phosphorus determination in commonly consumed foods. The obtained results suggest that the method verified in the present study may be used as an official analytical method for clear understanding of phosphorus database for national health promotion.

We report the chemical vapor deposition growth characteristics of graphene on various catalytic metal substrates such as Ni, Fe, Ag, Au, and Pt. 50-nm-thick metal films were deposited on SiO2/Si substrates using dc magnetron sputtering. Graphene was synthesized on the metal/SiO2/Si substrates with CH4 gas (1 SCCM) diluted in mixed gases of 10% H2 and 90 % Ar (99 SCCM) using inductively-coupled plasma chemical vapor deposition (ICP-CVD). The highest quality of graphene film was achieved on Ni and Fe substrates at 900˚C and 500 W of ICP power. Ni substrate seemed to be the best catalytic material among the tested materials for graphene growth because it required the lowest growth temperature (600˚C) as well as showing a low ICP power of 200W. Graphene films were successfully grown on Ag, Au, and Pt substrates as well. Graphene was formed on Pt substrate within 2 sec, while graphene film was achieved on Ni substrate over a period of 5 min of growth. These results can be understood as showing the direct CVD growth of graphene with a highly efficient catalytic reaction on the Pt surface.

본 연구에서는 식품공전에 제시되어 있는 microwave digestion 전처리방법과 유도결합 플라즈마 방출분광기을 이용하여 식품 중의 9종의 무기질(Na, Ca, K, P, Mg, Fe, Cu, Mn 및 Zn)을 측정하는 분석법에 대한 직선성, 정밀성 및 정확성 등의 분석법 유효성 검증을 실시하였다. 본 연구에 사용된 표준시료는 Certificated reference material1849a 조제분유로 미국 national institute of standards & technology에서 구입하였다. 직선성은 표준품을 사용한 표준검정곡선 측정농도범위에서 상관계수 0.9999 이상의 양호한 결과를 나타내었다. 검출한계는 0.1005 mg/kg, 정량 한계는 0.3351 mg/kg 으로 각각 나타났다. 또한 정밀도는 상대적표준편차(relative standard deviation)가 일내(withinday, n=3), 반복측정의 경우 0.09~4.80%, 일간(between-day, n=12)의 경우 1.19~18.19%로 양호한 결과를 나타내었으며 정확성은 회수율 90.35-110.63%로 매우 양호한 결과를 나타내었다. 따라서 microwave 전처리방법과 유도결합 플라즈마 방출분광기 측정법은 식품 중 9종의 무기질을 측정하는데 매우 유용할 것으로 사료되며 국민 건강 증진을 위한 식품성분표 데이터베이스 구축, 유통식품의 품질평가 등 공익적 분석사업에 이용될 수 있을 것으로 생각된다.

Graphene has been synthesized on 100- and 300-nm-thick Ni/SiO2/Si substrates with CH4 gas (1 SCCM) diluted in mixed gases of 10% H2 and 90% Ar (99 SCCM) at 900˚C by using inductively-coupled plasma chemical vapor deposition (ICP-CVD). The film morphology of 100-nm-thick Ni changed to islands on SiO2/Si substrate after heat treatment at 900˚C for 2 min because of grain growth, whereas 300-nm-thick Ni still maintained a film morphology. Interestingly, suspended graphene was formed among Ni islands on 100-nm-thick Ni/SiO2/Si substrate for the very short growth of 1 sec. In addition, the size of the graphene domains was much larger than that of Ni grains of 300-nm-thick Ni/SiO2/Si substrate. These results suggest that graphene growth is strongly governed by the direct formation of graphene on the Ni surface due to reactive carbon radicals highly activated by ICP, rather than to well-known carbon precipitation from carbon-containing Ni. The D peak intensity of the Raman spectrum of graphene on 300-nm-thick Ni/SiO2/Si was negligible, suggesting that high-quality graphene was formed. The 2D to G peak intensity ratio and the full-width at half maximum of the 2D peak were approximately 2.6 and 47cm-1, respectively. The several-layer graphene showed a low sheet resistance value of 718Ω/sq and a high light transmittance of 87% at 550 nm.

Graphene has been effectively synthesized on Ni/SiO2/Si substrates with CH4 (1 SCCM) diluted in Ar/H2(10%) (99 SCCM) by using an inductively-coupled plasma-enhanced chemical vapor deposition. Graphene was formed on the entire surface of the 500 nm thick Ni substrate even at 700 ˚C, although CH4 and Ar/H2 gas were supplied under plasma of 600 W for 1 second. The Raman spectrum showed typical graphene features with D, G, and 2D peaks at 1356, 1584, and 2710 cm-1, respectively. With increase of growth temperature to 900 ˚C, the ratios of the D band intensity to the G band intensity and the 2D band intensity to the G band intensity were increased and decreased, respectively. The results were strongly correlated to a rougher and coarser Ni surface due to the enhanced recrystallization process at higher temperatures. In contrast, highquality graphene was synthesized at 1000 ˚C on smooth and large Ni grains, which were formed by decreasing Ni deposition thickness to 300 nm.

Silicon dioxide as gate dielectrics was grown at 400˚C on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of O2 and N2O to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature N2O annealing, nitrogen can be supplied to the Si/SiO2 interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/SiO2 interface by plasma oxidation as the N2O molecule is broken in the plasma and because a dense Si-N bond is formed at the SiO2 surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the Si/SiO2 interface by the plasma oxidation of mixtures of O2/N2O gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.

BCI3/H2/Ar ICP(Inductively Coupled Plasma)를 이용한 GaN이 건식식각에 있어서 공정변수들이 식각 특성에 미치는 영향을 분석하고 적정조건을 도출하였다. 연구 결과 식각속도와 측벽수직도 공히 ICP 전력, bias 전압과 BCI3 조성의 증가, 공정압력의 감소에 의해 현저히 증가하며, 온도의 증가에 따라 다소간 증가하였고, 온도의 증가에 따라 다소간 증가하였고, BCI3조성이 가장 큰 영향을 미쳤다. 표면거칠기는 bias 전압 증가에 의해 크게 향상, BCI3 조성의 감소에 따라 향상되었으며 다른 변수는 큰 영향을 미치지 않았다. 결과적으로 ICP 전력 900W, bias 전압 400V, BCI3 조성 60%, 공정압력 4mTorr의 조건에서 175nm/min 정도의 CI2 사용 시와 유사한 높은 식각속도와 평탄한 표면이 얻어졌다. Bias 전압이 낮은 경우 식각 후 시료 표면에 GaCx로 추정되는 식각부산물이 관찰되었다.

사과주스 중의 Ca, P, Mg, Na, K의 함량을 ICP를 이용하여 측정하였다. 무기질 함량은 Ca 19∼311ppm, K 231∼1, 441ppm, Mg 6∼46ppm, Na 19∼115ppm 그리고 P 19∼304ppm이었다. 그리고 Na/K함량비는 모델주스의 경우 Na/K 비율이 0.02로 일정한 값을 나타내고 있지만 시판 사과주스는 0.06∼0.37을 나타내고 있다. 무기질이 강화된 시판주스는 P와 Ca함량이 매우 높았으며 30% 시판주스는 Na/K 비율이 매우 높았다.

자화된 유도결합형 C4F8 플라즈마로 SiO2를 건식식각시 실리콘 표면에 발생하는 손상과 오염에 대하여 연구하였다. 오염의 분석을 위해서 XPS, SIMS, TEM을 사용하였으며, 손상정도를 측정하기 위해서 HRTEM과 Schottky-diode 구성을 통한 I-V특성 측정을 사용하였다. 유도 결합형 C4F8 플라스마에 0에서 18Gauss까지의 자장이 가해짐에 따라서 실리콘 표면에 생기는 잔류막의 두께가 SiO2식각속도와 선택비의 증가와 함께 증가하였으며, XPS를 통하여 그 조성이 fluorine-rich에서 carbon-rich 한 상태로 변화함을 알 수 있었다. 자장을 가하지 않는 상태에서는 표면에서 40Å부근까지 고밀도의 손상층이 관찰되었으나, 자장을 가함에 따라서 노출된 손상층의 깊이는 깊어지나 그 밀도는 줄어들음을 HRTEM을 통하여 관찰 할 수 있었다. Schottky-diode를 통한 I-V특성곡선의 분석으로 자장이 증가함에 따라서 전기적인 손상이 감소함을 알 수 있었다.