This work involves the development of a novel waste-derived carbon dots (CDs) conjugated with silver (Ag) nanohybrid system-based Fluorescence Resonance Energy Transfer (FRET) sensor for the detection of melamine. CDs and Ag nanoparticles served as energy donors and energy acceptors, respectively. CDs were synthesized from orange peel waste through a combined hydrothermal and ultra-sonication route. The synthesized CDs had hydroxyl, amino, and carboxyl groups on their surface, explaining that waste-derived CDs can act as reducing and stabilizing agents and showed strong absorption and fluorescence emission at 305 and 460 nm, respectively. The bandgap, linear refractive index, conduction band, and valance band potential of CDs were observed to be 2.86, 1.849, 1.14, and 4.002 eV, respectively. No significant difference was observed in the fluorescence properties at different pH (acid and alkaline) and ionic concentrations. Given their fluorescent nature, the synthesized CDs were used for the detection of melamine. The fluorescence of CDs was found to be quenched by Ag+ due to the FRET energy transfer between CDs to Ag. Notably, the zeta potential of Ag@CDs was changed from − 28.7 mV to − 30.6 mV after the incorporation of Ag+. Ag@CDs showed excellent selectivity and sensitivity toward the sensing of melamine in the aqueous solutions with the limit of detection ~ 0.85 μM. Increasing the melamine level also raises the FL intensity of Ag@CDs. The substrate was effectively used in the detection of melamine in milk as a real application and the recovery percentage was found to be 98.03%. Moreover, other adulterants such as urea and formaldehyde can be detected selectively by Ag@CDs. Overall, the synthesized Ag@CDs can be used as an efficient material for sensing applications involving such food adulterants.

Platinum (Pt) catalysts dispersed on carbon-based support materials are generally used in the polymer electrolyte membrane (PEM) fuel cells. In this study, commercial graphene nanoplatelets (GNPs), with different surface areas (320, 530, 800 m2 g− 1), were used as catalyst supports in PEM fuel cells. These GNPs were also pyrolyzed under the inert atmosphere, with and without melamine, as the nitrogen (N) source. Various characterizations (Elemental analysis, FTIR, Raman spectroscopy, BET, TEM, HRTEM, SAED, XRD, TGA, ICP-MS, contact angle measurement, CV, ORR, chronoamperometry, EIS, PEM fuel cell performance test) were performed for the detailed analysis of Pt/GNPs. Based on the three-electrode cell system, the lowest electrochemical surface area (ECSA) loss (29.9%), Pt mass activity loss (20.3%) and overall (charge and mass) resistance (42.2 Ω) were obtained with the Pt/M-530 catalyst. According to the in-situ PEM fuel cell performance results, the specific peak power density was recorded as (450 mW mg Pt− 1) for the Pt/R-530 catalyst, which has also the second most hydrophobic catalyst layer surface with the 146.5° ± 1.28° contact angle value. On the heels of Pt/R-530, the two best performances also belong to the Pt/M-530 (391 mW mg Pt− 1) and Pt/P-530 (378 mW mg Pt− 1) catalysts of the same group.

Porous carbons have been widely used as electrode material for supercapacitors. However, commercial porous carbons, such as activated carbons, have low electrochemical performance. Nitrogen-doping is one of the most promising strategies to improve electrochemical performance of porous carbons. In this study, nitrogen self-doped porous carbon (NPC) is prepared from melamine foam by carbonization to improve the supercapacitive performance. The prepared NPC is characterized in terms of the chemical structures and elements, morphology, pore structures, and electrochemical performance. The results of the N2 physisorption measurement, X-ray diffraction, and Raman analyses reveal that the prepared NPC has bimodal pore structures and pseudo-graphite structures with nitrogen functionality. The NPC-based electrode exhibits a gravimetric capacitance of 153 F g−1 at 1 A g−1, a rate capability of 73.2 % at 10 A g−1, and an outstanding cycling ability of 97.85% after 10,000 cycles at 10 A g−1. Thus, the NPC prepared in this study can be applied as electrode material for high-performance supercapacitors.

In this paper, nitrogen-doped reduced graphene oxide(rGO) is obtained by thermal annealing of nitrogen-containing compounds and graphene oxide (GO) manufactured by modified Hummers' method. We use melamine as a nitrogen-containing compound and treat GO thermally with melamine at over 800 ~ 1,000℃ and 1 ~ 3 hr under Ar atmosphere. The electrical conductivity of doped rGO is measured by 4-point probe method. As a result, nitrogen contents on rGO are found to be in the range of 2.5 to 12.5 at% depending on the doping conditions after thermal annealing. The main doping site on graphene oxide is changed from pyridinic-N and pyrrolinic N to the graphitic site as the heat treatment temperature increases. The electrical conductivity of doped rGO increases as the N doping content increases. As the thermal treatment time increases, the change of both total doping contents and doping sites is slight and the surface resistance is remarkably reduced, which is caused by healing effects of doped graphene oxide at high temperature.

The present study aimed to prepare a novel efficient flame retardant additive for polypropylene. The new flame retardant was prepared by chemical grafting of melamine to graphene oxide with the aid of thionyl chloride. Fourier-transform infrared spectroscopy and thermogravimetric analysis proved that melamine had been successfully grafted to the graphene oxide. The modified graphene oxide was incorporated into polypropylene via solution mixing followed by anti-solvent precipitatio. Homogeneous distribution as well as exfoliation of the nanoplatelets in the polymer matrix was observed using transmission electron microscopy. Thermogravimetric analysis showed a significant improvement in the thermo-oxidative stability of the polymer after incorporating 2 wt% of the modified graphene oxide. The modified graphene oxide also enhanced the limiting oxygen index of the polymer. However, the amount of improvement was not enough for the polymer to be ranked as a self-extinguishing material. Cone calorimetry showed that incorporating 2 wt% of the modified graphene oxide lowered total heat release and the average production rate of carbon monoxide during burning of the polymer by as much as 40 and 35%, respectively. Hence, it was concluded that the new flame retardant can retard burning of the polymer efficiently and profoundly reduce suffocation risk of exposure to burning polymer byproducts.

멜라민수지 조리기구 제조에 사용되는 formaldehyde와 phenol의 경우 식품에 이행될 우려가 있다. 이에 본 연구에서는 국내에서 유통되고 있는 멜라민수지 조리기구 222 건에 대하여 formaldehyde와 phenol의 식품유사용매로의 이행량을 조사하였다. 멜라민수지 조리기구는 컵(14), 공기(75), 접시(85), 숟가락(10), 젓가락(4), 식판(8), 주걱(4), 뒤지게(9) 및 국자(12)등을 수거하였다. 식품유사용매로는 물, 4% 초산, 20% 에탄올, n-헵탄을 사용하였다. 한국의 멜라민수지 기구 및 용기·포장 중 formaldehyde와 phenol의 용출기준은 각각 4 mg/L, 5 mg/L 이며, 수거된 222건 멜라 민수지 조리기구 모두 기준·규격에 적합하였다. 멜라민 수지 조리기구 중 formaldehyde와 phenol의 이행량은 각각 N.D~2,949 μg/L, N.D~78 μg/L이었다. 위 분석결과는 멜라민수지 기구 및 용기·포장의 안전관리의 과학적 근거 자료로 제공될 수 있을 것으로 판단된다.

Formaldehyde and phenol used in the production of melamine-wares may be intended to come into foodstuffs. So this study investigated the migration of formaldehyde and phenol from 222 articles Articles were cups(14), bowls(75), plates(85), spoons(10), chopsticks(4), food trays(8), rice paddles(4), spatulas(9) and scoops(12). The food stimulants were 4% acetic acid, 20% ethanol, distilled water and n-heptane. Korea regulation (Standards and specifications for food utensils, containers and package) specifies migration limits for formaldehyde and phenol in food stimulants. Formaldehyde and phenol are restricted by 4 mg/L, 5 mg/L respectively. In all cases the migration of formaldehyde and phenol were below the limit set in Korea regulation. The level of formaldehyde and phenol migrated to food simulants were in the range of N.D~2.949 mg/L, N.D~0.078 mg/L respectively. These migration results of formaldehyde and phenol will provide a scientific basis for the safety management of melamine-wares.

Melamine has been reported to be responsible for kidney stones and renal failure among infants and children. Con-ventional detection methods, High-Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC), aresensitive enough to detect trace amounts of the contaminant, but they are time consuming, expensive, and labor-intensive. Hyperspectral imaging methods, which combine spectroscopy and imaging, can provide rapid and non-destructive means to assess the quality and safety of agricultural products. In this study, near-infrared hyperspectralreflectance imaging combined with partial least square regression analysis was used to predict melamine particleconcentration in dry milk powder. Melamine particles, with concentration levels ranging from 0.02% to 1% byweight ratio (g/g), were mixed with dry milk powder and used for the experiment. Hyperspectral reflectance imagesin the wavelength range from 992.0nm to 1682.1nm were acquired for the mixtures. Then PLSR models weredeveloped with several preprocessing methods. Optimal wavelength bands were selected from 1454.5nm to 1555.6nm using beta-coefficients from the PLSR model. The best PLSR result for predicting melamine concentration inmilk powder was obtained using a 1st order derivative pretreatment with Rv=0.974, SEP=±0.055%, and F=6.

The present study investigated the urinary tract toxicity of melamine alone or in combination with cyanuric acid in rats. Male rats were orally administered melamine alone (800 mg/kg) or melamine plus cyanuric acid (50 mg/kg each) for 3 consecutive days. Although melamine treatment did not show any significant difference in body weight, kid- ney or urinary bladder weight, serum blood urea nitrogen (BUN) or creatinine levels, it caused a decrease in urinary pH and mild histopathological alterations in the kidney and urinary bladder. In contrast, co-administration of melamine and cyanuric acid induced a decrease in body weight, an increase in kidneys and urinary bladder weights, and an elevation in serum BUN and creatinine levels, which were not observed in animals treated with melamine alone. His- topathological examination showed that the incidence and severity of histopathological lesions in the kidney and uri- nary bladder were much higher than those in the melamine group. Urinalysis revealed an increase in urine occult blood, leukocytes and protein and a decrease in urinary pH. These results indicate that concomitant administration of cyanuric acid synergistically potentiated the urinary tract toxicity induced by melamine in rats. In this study, we first demon- strated the synergistic toxic effects of melamine in combina- tion with cyanuric acid on urinary bladder and urinalysis in rats.

Melamine has raised international concerns for its catastrophic health effects from tainted infant formula. This report concerns the developmental validation of a sensitive HPLC/MS/MS and GC/MS methods about melamine and cyanuric acid in human urine and serum. Analytical detection ranges of LC/MS was from 0.2 to 5.0 ng/mL and 2.0 to 60.0 ng/mL about melamine and cyanuric acid, respectively. The limits of quantification and confirmation are 0.2 ng/mL for both analytes in human urine and serum by LC/MS/MS. The range of recovery was 91.6%, and 107.6% for cyanuric acid and melamine in urine, respectively. The range of precision coefficient variation was from 2.0%, to 11.8% for cyanuric acid and melamine in urine. The range of recovery was from 94.9%, to 119.0% about cyanuric acid and melamine in serum, respectively. The range of precision coefficient variation from was 3.7%, and 13.5% about cyanuric acid and melamine in serum. Analytical detection ranges of GC/MS were 5.0 to 100.0 ng/mL about melamine and cyanuric acid, respectively. The limits of quantification and confirmation are 5.0 ng/mL for both analytes in human urine and serum by GC/MS. The range of recovery was from 83.7%, to 114.5% for cyanuric acid and melamine in urine, respectively. The range of precision coefficient variation was 3.5%, and 10.7% for cyanuric acid and melamine in urine. The range of recovery was 94.4%, and 110.7% for cyanuric acid and melamine in serum,respectively. The range of precision coefficient variation from was 3.9%, and 13.8% for cyanuric acid and melamine in serum. Several changes were taken to optimize performance by this method.

Magnesium hydroxide-melamine core-shell particles were prepared through the coating of melamine monomer on the surface of magnesium hydroxide in the presence of phosphoric acid. The melamine monomer was dissolved in hot water but recrystallized on the surface of magnesium hydroxide by quenching to room temperature in the presence of phosphoric acid. The core-shell particle was applied to low-density polyethylene/ ethylene vinyl acetate (LDPE/EVA) resin by melt-compounding at 180˚C as flame retardant. The effect of magnesium hydroxide and melamine content has been studied on the flame retardancy of the core-shell particles in LDPE/EVA resin according to the preparation process and purity of magnesium hydroxide. Magnesium hydroxide prepared with sodium hydroxide rather than with ammonia solution revealed higher flame retardancy in core-shell particles with LDPE/EVA resin. At 50 wt% loading of flame retardant, core-shell particles revealed higher flame retardancy compared to that of the exclusive magnesium hydroxide in LDPE/EVA composite, and it was possible to satisfy the V0 grade in the UL-94 vertical test. The synergistic flame retardant effect of magnesium hydroxide and melamine core-shell particles was explained as being due to the endothermic decomposition of magnesium hydroxide and melamine, which was followed by the evolution of water from the magnesium hydroxide and porous char formation due to reactive nitrogen compounds, and carbon dioxide generated from melamine.

Melamincyanurate(MC), as an non halogen flame retardant are used as the polymer and plastic materials. In this study, melamine and cyanuric acid were used for the synthesis of MC. The optimum condition of synthetic MC were controlled by different molar ratio of melamine to cyanuric acid. MC was modified by coupling reaction with four different agents. The influences of modified MC were based on the coupling agent types. Preparation methods are available to offer the prospect of improved morphology control deposit stability in polyol. The results reveal that glycidoxypropyltrimethoxysilane(GDS) has the best storage stability. The best properties were obtained with melamine and cyanuric acid from 1:1 molar ratio. Modification of MC through coupling agent can efficiently enhanced the deposit stability in polyol up to 30 %.

This study surveyed the change of housewives’ purchase behaviors by food safety incidents; the outbreak of 2008 Melamine incident in Korea as for example. 565 housewives in Gunsan were interviewed in March 2009. 52.3% of respondents were regarded as unsatisfactory for food safety management in Korea. Despite the result of scientific assessment for melamine, 74.6% of respondents were yet regarded as health-threatening substance. By the point of before, during and after Melamine-related food safety incident, we were surveyed the level of purchase for melamine-related food items as five scales, the results were 2.47 ± 0.97, 1.80 ± 0.92 and 1.62 ± 0.92, respectively (p < 0.001). After the incident happened, the purchase level was even more reduced. This study also found that there were significance difference (p < 0.05) among the respondents’ knowledge for melamine toxicity and food safety management in Korea concerning housewives’ purchase behaviors, i.e. the more accurately for melamine toxicity and higher satisfactory of consciousness of food safety, there were less change of purchase behaviors. In conclusion, the consciousness of food safety and accurate knowledge of hazards were significantly affected for the change of housewives’purchase behaviors by food safety incidents. Therefore, it can be suggested that the need for more scientific risk communication strategies with consumer.

An acrylic resin was synthesized with several monomers, styrene(St), 2-hydroxyethyl methacrylate(2-HEMA), n-butyl acrylate, methyl methacrylate, and acetoacetoxyethl methacrylate(AAEM) to prepare a high-solid coatings. Then, a high-solid acryl/melamine coatings was prepared by curing the acrylic resin with a curing agent, hexamethoxymethylmelamine(HMMM). The curing behavior of the acrylic resin with HMMM was investigated by the Ozawa method using DSC. For AAEM/HMMM and 2-HEMA/HMMM curing reactions, activation energies were 33.01 and 27.12 kcal/mol and frequency factors were 9.54×1015 and 1.53×1013 min-1, respectively. From the results, it was found out that 2-HEMA showed higher reactivity with the curing agent than AAEM.