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Sample records for melamine

  1. The effects of isotope-labeled analogs on the LC-IDMS measurement by comparison of ESI responses and matrix effect of melamine,13C3-melamine,13C3+15N3-melamine, and15N3-melamine.

    Science.gov (United States)

    Li, Xiu Qin; Zhang, Qing He; Yang, Zong; Li, Hong Mei; Huang, Dong Feng

    2017-05-01

    In this paper, the effect of isotope-labeled analogs on the liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) measurement was evaluated based on the comparison research of electrospray ionization responses (ESI) and matrix effect of melamine, 13 C 3 -melamine, 13 C 3 + 15 N 3 -melamine, and 15 N 3 -melamine. The isotope-labeled melamines had similar ionization efficiency with melamine in the electrospray ionization source, but the intensity of corresponding quantitative fragment ions had distinctive differences. Based on the density functional theory at the B3LYP/6-311+G** level, this phenomenon was explained very well. The rare cleavage pathways of melamine, which just could be exactly identified by 15 N-labeled melamines, resulted in the difference of quantitative fragment ions between 15 N-labeled melamines and melamine. The interaction of ESI response between melamine and isotope-labeled melamines was investigated using MRM monitor mode. 15 N-labeled melamine had significant ion inter-suppression effect on melamine, while 13 C-labeled melamine had little influence on melamine. Finally, the influence of different isotope-labeled melamines on the LC-IDMS result was evaluated using the IDMS correction factor (θ). Taking the determination of melamine in milk powder as an example, the matrix effects of different isotope-labeled melamines and melamine had notable difference and the impact of this difference on the measurement results depended on the concentrations of analyte and matrix solution. It was worth noting that 15 N 3 -melamine exhibited significant ion suppression to melamine in matrix solution. The deviation of the results from IDMS method might reach 59% using 15 N 3 -melamine as internal standard in special matrix solution. Graphical Abstract The comparison of ESI responses of melamine, 13 C 3 -melamine, 13 C 3 + 15 N 3 -melamine and 15 N 3 -melamine.

  2. Melamine Induces Oxidative Stress in Mouse Ovary.

    Directory of Open Access Journals (Sweden)

    Xiao-Xin Dai

    Full Text Available Melamine is a nitrogen heterocyclic triazine compound which is widely used as an industrial chemical. Although melamine is not considered to be acutely toxic with a high LD50 in animals, food contaminated with melamine expose risks to the human health. Melamine has been reported to be responsible for the renal impairment in mammals, its toxicity on the reproductive system, however, has not been adequately assessed. In the present study, we examined the effect of melamine on the follicle development and ovary formation. The data showed that melamine increased reactive oxygen species (ROS levels, and induced granulosa cell apoptosis as well as follicle atresia. To further analyze the mechanism by which melamine induces oxidative stress, the expression and activities of two key antioxidant enzymes superoxide dismutase (SOD and glutathione peroxidase (GPX were analyzed, and the concentration of malondialdehyde (MDA were compared between control and melamine-treated ovaries. The result revealed that melamine changed the expression and activities of SOD and GPX in the melamine-treated mice. Therefore, we demonstrate that melamine causes damage to the ovaries via oxidative stress pathway.

  3. Migration of formaldehyde and melamine monomers from kitchen- and tableware made of melamine plastic

    DEFF Research Database (Denmark)

    Lund, K.H.; Petersen, J.H.

    2006-01-01

    Migration of one or both formaldehyde and/or melamine monomers was found in seven of ten tested melamine samples bought on the Danish market. The samples were a bowl, a jug, a mug, a ladle, and different cups and plates. No violation of the European Union-specific migration limits for melamine (30...

  4. Inhibition of Heme Peroxidases by Melamine

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    Pattaraporn Vanachayangkul

    2012-01-01

    Full Text Available In 2008 melamine-contaminated infant formula and dairy products in China led to over 50,000 hospitalizations of children due to renal injuries. In North America during 2007 and in Asia during 2004, melamine-contaminated pet food products resulted in numerous pet deaths due to renal failure. Animal studies have confirmed the potent renal toxicity of melamine combined with cyanuric acid. We showed previously that the solubility of melamine cyanurate is low at physiologic pH and ionic strength, provoking us to speculate how toxic levels of these compounds could be transported through the circulation without crystallizing until passing into the renal filtrate. We hypothesized that melamine might be sequestered by heme proteins, which could interfere with heme enzyme activity. Four heme peroxidase enzymes were selected for study: horseradish peroxidase (HRP, lactoperoxidase (LPO, and cyclooxygenase-1 and -2 (COX-1 and -2. Melamine exhibited noncompetitive inhibition of HRP (9.5±0.7mM, and LPO showed a mixed model of inhibition (14.5±4.7mM. The inhibition of HRP and LPO was confirmed using a chemiluminescent peroxidase assay. Melamine also exhibited COX-1 inhibition, but inhibition of COX-2 was not detected. Thus, our results demonstrate that melamine inhibits the activity of three heme peroxidases.

  5. Deposition of melamine in eggs from laying hens exposed to melamine contaminated feed.

    Science.gov (United States)

    Chen, Yiqiang; Yang, Wenjun; Wang, Zongyi; Peng, Yong; Li, Bin; Zhang, Liying; Gong, Limin

    2010-03-24

    The deposition profile of melamine was studied in eggs obtained from laying hens fed melamine contaminated feed. A total of 180 laying hens were divided into five groups and were fed diets spiked with 0, 5, 25, 50, or 100 mg of melamine per kg of feed. Eggs collected on days 1, 3, 5, 7, 9, 11, 13, and 15 were analyzed by a gas chromatography-mass spectrometry method, which was fully validated for melamine analysis prior to use. For each treatment group, the melamine level in the eggs was similar from day 1 to day 15 (P > 0.05), suggesting that laying hens did not accumulate melamine for later deposition in eggs. The average melamine concentrations in eggs were 0.00 (below limit of detection), 0.16, 0.47, 0.84, and 1.48 mg/kg for the 0, 5, 25, 50, and 100 mg/kg treatment groups, respectively, which demonstrated an apparent dose-response relationship, and a safety threshold of 164 mg/kg melamine in the feed of laying hen was estimated when a maximum tolerance level of 2.5 mg/kg melamine in egg was adopted. These results provide a scientific basis for the risk assessment of melamine in feeds fed to laying hens.

  6. Effects of different doses of melamine in the diet on melamine ...

    African Journals Online (AJOL)

    The objectives of this paper were to evaluate the effects of feeding diets containing different levels of melamine on melamine concentrations in milk, plasma, rumen fluid, urine and feces in Holstein dairy cows. Sixteen Chinese Holstein dairy cows fixed with permanent ruminal cannulas were assigned to 1 of 4 treatments ...

  7. Synthesis of Melamine-d6 and the Feasibility of Deuterium Labeled Compounds as Internal Standard

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    GUO Yang-zhen

    2015-11-01

    Full Text Available S-triazine is an important chemical intermediate. Melamine belongs to s-triazine, which has been widely used as an additive in the food industry. To study the stable isotope labeling method of heterocyclic triazine compounds and its application, one step synthesis of melamine-d6 was achieved with a yield of 30% (calculate in ND4OD, which started from ND4OD by the reaction with cyanuric chloride. According to the exchange mechanism of H/D, the feasibility and the necessary conditions were discussed for applying deuterium labeled compounds in isotope dilution mass spectrometry method.

  8. CT findings of melamine caused urinary calculi

    International Nuclear Information System (INIS)

    Hou Zhenzhou; Xiao Ye; Chen Xia; Zhong Yaping; Tao Jie; Jiao Qi; Dong Fengqun; Wang Xiaoying

    2009-01-01

    Objective: To analyze the CT findings of melamine induced urinary calculi. Methods: Nineteen children with a history of ingestion of melamine contaminated infant formula milk were studied, including 12 males and 7 females, age ranged from 50 days to 5 years. Results: CT demonstrated renal pelvic and ureteral stones in 13 cases, with urinary obstruction in 9 of them. The size of the stones ranged from 0.3 cm x 0.3 cm to stag-horn calculus. Tine density of the stones measured from a low of 40-70 HU up to a high of 410 HU with an average density of 160 HU. Conclusion: CT scan is an excellent modality in demonstrating urinary tract calculi caused by melamine. It is the method of choice when ultrasound examinations are equivocal. (authors)

  9. Characterization of a novel melamine-degrading bacterium isolated from a melamine-manufacturing factory in China.

    Science.gov (United States)

    Wang, Han; Geng, Chunnu; Li, Jiangwei; Hu, Anyi; Yu, Chang-Ping

    2014-04-01

    Melamine (2,4,6-triamino-1,3,5-triazine, C3H6N6), belonging to the s-triazine family, is an anthropogenic and versatile raw material for a large number of consumer products and its extensive use has resulted in the contamination of melamine in the environment. A novel melamine-degrading bacterium strain CY1 was isolated from a melamine-manufacturing factory in China. The strain is phylogenetically different from the known melamine-degrading bacteria. Approximately, 94 % melamine (initial melamine concentration 4.0 mM, initial cell OD 0.05) was degraded in 10 days without the addition of additional carbon source. High-performance liquid chromatography showed the production of degradation intermediates including ammeline, ammelide, cyanuric acid, biuret, and urea. Kinetic simulation analysis indicated that transformation of urea into ammonia was the rate-limiting step for the degradation process. The melamine-cyanurate complex was formed due to self-assembly of melamine and cyanuric acid during the degradation. The tracking experiment using CY1 cells and (13)C3-melamine showed that the CY1 could mineralize s-triazine ring carbon to CO2. The strain CY1 could also catalyze partial transformation of cyromazine, a cyclopropyl derivative of melamine, to 6-(cyclopropylamino)-[1,3,5]triazine-2,4-diol.

  10. Melamine structures on the Au(111) surface

    NARCIS (Netherlands)

    Silly, Fabien; Shaw, Adam Q.; Castell, Martin R.; Briggs, G. A. D.; Mura, Manuela; Martsinovich, Natalia; Kantorovich, Lev

    2008-01-01

    We report on a joint experimental and theoretical study of the ordered structures of melamine molecules formed on the Au(111)-(22 x root 3) surface. Scanning tunneling microscopy (STM) images taken under UHV conditions reveal two distinct monolayers one of which has never been reported before on

  11. Transfer efficiency of melamine from feed to milk in lactating dairy cows fed with different doses of melamine.

    Science.gov (United States)

    Shen, J S; Wang, J Q; Wei, H Y; Bu, D P; Sun, P; Zhou, L Y

    2010-05-01

    This study was conducted to investigate the transfer efficiency of melamine (1,3,5-triazine-2,4,6-triamine) from feed to milk of lactating cows fed with different doses of melamine. Twenty-four China Holstein dairy cows were divided into 2 blocks according to milk yield (block 1 and block 2 for low- and high-producing cows). Cows of block 1 or block 2 each were randomly assigned to 1 of 4 treatments in a randomized complete block design and each treatment had 6 cows. The cows of treatments 1 to 4 were dosed with melamine at 0 (control), 90 (treatment 1), 270 (treatment 2), and 450 (treatment 3) mg/d per cow, respectively. The trial lasted 19 d. During the first 13 d, cows were fed melamine at the respective treatment levels, and the last 6 d was the clearance period after melamine was withdrawn. The results indicated that the levels of melamine used did not affect milk yield or composition. The mean milk melamine concentration increased during the initial 3 d after melamine feeding in all the melamine-supplemented groups, and then fluctuated slightly over the remaining 10 d of melamine feeding. No melamine was detected in the milk of any groups on d 4 of the clearance period. Milk melamine concentration measured between 3 to 13 d was significantly affected by melamine feeding doses, but was not influenced by milk yield. The transfer efficiency of melamine from feed to milk was not affected by melamine doses (0.95, 0.70, and 0.66% for treatments 1, 2, and 3, respectively), but was linearly related with milk yield (0.56% for block 1 and 0.95% for block 2, R(2)=0.80). The milk melamine concentration was linearly related with melamine intake (R(2)=0.84). The present study demonstrated that when the daily intake of melamine exceeds 312.7mg/cow, the milk should not be used to produce infant formula powder. Copyright 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. A novel fluorometric determination of melamine using cucurbit[7]uril

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yunyou, E-mail: zy161299@mail.ahnu.edu.c [Anhui Key Laboratory of Functional Molecular Solids and Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Yang Juan; Liu Min; Wang Sufan; Lu Qin [Anhui Key Laboratory of Functional Molecular Solids and Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)

    2010-05-15

    Melamine is a toxic compound to both animals and human beings, and is connected to various diseases, such as kidney stones and bladder cancer. For the efficient detection of melamine, we have developed a novel sensitive cucurbit[7]uril (CB7) sensor with a detection limit at 0.20 mug mL{sup -1}, and applied it to detect melamine in tainted milk. Fluorescence studies indicate that CB7 forms complex with melamine in a 1:1 mole ratio. The binding constant at various temperatures has been calculated and the interaction mechanism has been discussed based on molecular modeling result.

  13. Melamine-modified urea formaldehyde resin for bonding particleboards

    Science.gov (United States)

    Chung-Yun Hse; Feng Fu; Hui Pan

    2008-01-01

    For the development of a cost-effective melamine-modified urea formaldehyde resin (MUF), the study evaluated the effects of reaction pH and melamine content on resin properties and bond performance of the MUF resin adhesive systems. Eight resins, each with three replicates, were prepared in a factorial experiment that included two formulation variables: two reaction...

  14. In vitro degradation of melamine by ruminal microorganisms

    African Journals Online (AJOL)

    Tanja&Jana

    2015-05-17

    May 17, 2015 ... The industrial chemical melamine (1,3,5-triazine-2,4,6-triamine) is used in manufacturing plastic ware, laminates and paints. Pure melamine has a ... an attractive adulterant for protein feedstuffs, as demonstrated during the 2008 worldwide pet food recalls and the 2009 tainted infant formula incidents in ...

  15. Self-Assembled Microwires of Terephthalic Acid and Melamine

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    Hong Wang

    2017-07-01

    Full Text Available Self-assembled microwires of terephthalic acid (TPA and melamine are prepared through the evaporation of water in a solution mixture of TPA and melamine. The microwires were characterized by using scanning electron microscope (SEM, attenuated total reflection infrared (ATR-IR spectra, and cross-polarized optical microscopy (CPOM. The TPA•M microwires showed semi-conductive properties.

  16. Effects of different doses of melamine in the diet on melamine ...

    African Journals Online (AJOL)

    Administrator

    2011-04-25

    Apr 25, 2011 ... in the manufacture of plastics, laminates, and in some fertilizers. A driving force for the adulteration of feedstuff and milk products with melamine is that its high nitrogen content (66% nitrogen by mass) increases the apparent protein content detected by standard protein analysis tests, for instance, Kjeldahl or ...

  17. Effect of Melamine Sponge on Tooth Stain Removal.

    Science.gov (United States)

    Otsuka, Takero; Kawata, Toshitsugu

    2015-01-01

    To investigate the stain removal ability of melamine sponge before aesthetic tooth whitening in extracted teeth. Melamine sponge of thickness 40 mm was compressed and the destruction of the partition wall structure during the compression process was examined under a stereoscopic microscope. An extracted human tooth was cleaned by normal polishing or with melamine sponge for 90 s. To evaluate the stain level, the tooth surfaces were photographed under a stereoscopic microscope at 0, 30, 60 and 90 s. The residual stained region was traced in a high-magnification photograph, and the stain intensity was presented as a change, relative to the intensity before the experiment (0 s). Mechanical cleaning by toothbrushing produced polishing scratches on the tooth surface, whereas use of the melamine sponge resulted in only minimal scratches. As the compression level increased, the stain-removing effect tended to become stronger. Melamine sponge can remove stains from the tooth surface more effectively and less invasively compared to a conventional toothbrush. As no new scratches are made on the tooth surface when using a melamine sponge brush, the risk of re-staining is reduced. Cleaning using a melamine sponge brush can be easily and effectively performed at home and in a dental office.

  18. Spectral and Thermal Degradation of Melamine Cyanurate

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    V. Sangeetha

    2013-01-01

    Full Text Available Melamine cyanurate, an organic crystalline complex was, synthesized by evaporation of an aqueous solution containing equimolar quantities of melamine and cyanuric acid. The synthesized compound has been subjected to various characterizations like Powder XRD, FT-IR, TG-DTG, SEM, and SHG. The presence of sharp diffraction peaks in the XRD confirms that the products are highly crystalline. The average particle size was calculated using the Debye-Scherrer formula, and it was found to be 3.067 μm. Thermal behavior of the grown crystal has been studied by TG-DTG analysis. From TG-DTG, it is found that the title crystal possesses good thermal stability. The activation energy was calculated using the Broido, Coats-Redfern, and Horowitz-Metzger methods. A sharp peak exothermic peak at 405.40°C was assigned as the melting point of the title material. SEM reveals the morphology of the synthesized salt. No detectable signal was observed during the Kurtz-Perry technique.

  19. Synthesis and thermal degradation studies of melamine formaldehyde resins.

    Science.gov (United States)

    Ullah, Sami; Bustam, M A; Nadeem, M; Naz, M Y; Tan, W L; Shariff, A M

    2014-01-01

    Melamine formaldehyde (MF) resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA). The maximum percentage of solid content (69.7%) was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.

  20. Synthesis and Thermal Degradation Studies of Melamine Formaldehyde Resins

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    Sami Ullah

    2014-01-01

    Full Text Available Melamine formaldehyde (MF resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA. The maximum percentage of solid content (69.7% was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.

  1. Melamine dependent fluorescence of glutathione protected gold nanoclusters and ratiometric quantification of melamine in commercial cow milk and infant formula

    Science.gov (United States)

    Kalaiyarasan, Gopi; K, Anusuya; Joseph, James

    2017-10-01

    Companies processing the milk for the further production of powdered infant formulation normally check the protein level through a test measuring nitrogen content. The addition of melamine which is a nitrogen-rich organic chemical in milk increases the nitrogen content and therefore enhances its apparent protein content. However, the melamine causes kidney failure and death owing to the formation of kidney stone. Thus the determination of melamine in humans and milk products have gained great significance in recent years. The gold nanoclusters (AuNCs) have attracting features due to its unique electronic and optical properties like fluorescence nature. Therefore one can use AuNCs in the field of biosensor, bio-imaging, nanobiotechnology, drug delivery, diagnosis etc. We report, a new ratiometric nanosensor established for the selective and sensitive detection of melamine based optical sensing using glutathione stabilized AuNCs. The AuNCs were characterized by high-resolution transmission electron microscopy (HR-TEM), UV-visible and Photoluminescence (PL) spectroscopic techniques. In the presence of melamine, the PL intensity at 430 nm increases owing to the (turn-on) enhancement in fluorescence, whereas PL intensity at 610 nm decreases due to the melamine-induced aggregation and subsequent aggregation-enhanced emission quenching. The observed changes were ascribed to the hydrogen bonding interaction between melamine and AuNCs, which led to the aggregation of the nanoclusters. This was confirmed by dynamic light scattering and HR-TEM measurements. The present probe showed an extreme selectivity towards the determination of 28.2 μM melamine in the presence of 100-fold excess of common interfering molecules such as Alanine, Glycine, Glucose, Cystine etc. The proposed method was successfully applied to determine melamine in cow milk.

  2. Melamine, beyond the kidney: A ubiquitous endocrine disruptor and neurotoxicant?

    Science.gov (United States)

    Bolden, Ashley L; Rochester, Johanna R; Kwiatkowski, Carol F

    2017-10-05

    Melamine is commonly used in a variety of consumer products such as furniture, dining ware, and food utensils. The chemical infamously gained worldwide attention by its illegal addition to a variety of foodstuffs in order to falsify protein content, which led to serious, sometimes fatal, health impacts in children and pets. This resulted in a large amount of published primary studies and reviews of the impacts of melamine exposure on kidney function. However, a growing body of literature suggests that melamine may have impacts beyond renal dysfunction. We conducted a scoping review of this literature which yielded more than 40 studies with human, animal, and in vitro findings. Neurological impacts, reproductive function, and anthropometric outcomes were identified as possible candidates for systematic review based on evidence stream and replication of endpoints. The results of this analysis provide a basis for prioritizing future research on health impacts associated with melamine exposure. Copyright © 2017. Published by Elsevier B.V.

  3. LAJU PELEPASAN DIAZINON DARI MIKROKAPSUL BERBASIS MELAMIN FORMALDEHID

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    Noviana Utami Ciptaningtyas Suhartaya

    2014-05-01

    Full Text Available The microcapsules containing diazinon as the core material and melamine formaldehyde as the membrane material have been synthesized by in situ polimerization method. The microcapsule membrane on this researches was modified in two types, the first, melamine formaldehyde (MF and the second types, melamine formaldehyde added with sodium dodecyl sulphate and polyvinyl alcohol (MF-SDSPVA. This research aims to study the effect of pH and temperature on the release rate of diazinon in aqueous medium. The results showed that the pH and temperature has little effect on the release rate of diazinon from microcapsule based on melamine formaldehyde. This is due to the diffusion through the microcapsule membrane is not influenced by the pH and temperature of the solution outside of microcapsule.

  4. Melamine phosphomolybdate - a new ion selective compound for caesium

    International Nuclear Information System (INIS)

    Mehta, B.J.; Baxi, D.R.

    1976-01-01

    Preparation of melamine phosphomolybdate is described and its composition is determined. The compound is found to be granular having much higher selectivity for Cs + than that of ammonium phosphomolybdate. (orig.) [de

  5. Assessment of melamine contamination in crop, soil and water in China and risks of melamine accumulation in animal tissues and products.

    Science.gov (United States)

    Qin, Yuchang; Lv, Xiaowen; Li, Jun; Qi, Guanghai; Diao, Qiyu; Liu, Guohua; Xue, Min; Wang, Jiaqi; Tong, Jianming; Zhang, Liying; Zhang, Keying

    2010-07-01

    The scandal of melamine-adulterated infant formula in China in September 2008 demanded the need to assess the extent of melamine contamination in the environment and food products and possible risks of consuming melamine-contaminated diets. In this work, our extensive work tested water, soil and crop samples from 21 provinces in China. Soils nearby and waste waters from melamine-manufacturing factories were examined, and the highest melamine concentrations in waste water and soil samples were 226.766 and 41.136 mg/kg, respectively. Six of 94 irrigation water samples had melamine at a concentration of 21-198 microg/L. Only 1 sample collected from 124 farmlands farther than 150 km from melamine factories was detected for melamine at a content of 176 microg/L. Only 3 out of 557 crop samples contaminated more than 1mg/kg melamine, with the highest level of 2.05 mg/kg in a wheat sample. When basal diets contained 2mg/kg melamine were fed to various animals, deposition of melamine in animal tissues and products was all lower than 122 microg/kg. The melamine deposition was much higher (e.g., 4483 microg/kg in the kidney of chicken) when diets contained 100 mg/kg melamine but was found to be completely depleted after 96 h for all animals after switching to the basal diets. Our work may be valuable to regulate melamine production and monitor the safety of food and animal products. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. Synthesis and the Effects of New Melamine Superplasticizer on the Properties of Concrete

    OpenAIRE

    Wang, Huqun; Yang, Xiaofeng; Xiong, Weifeng; Liu, Xiaobin; Zhang, Zhimin

    2013-01-01

    This work deals with the synthesis of new melamine superplasticizer (NMS) with high molecule weight and comparatively high processing thermostability by the reaction among melamine, formaldehyde, and sulfonated glucose. The surface activity and the structure of new melamine superplasticizer and their performance in concrete were evaluated. The effect of molecular weight of synthesized new melamine superplasticizer on the performance of the concrete was determined. The results showed that the ...

  7. Using the Melamine Contamination of Foods to Enhance the Chemistry Classroom

    Science.gov (United States)

    Kimbrough, Doris Renate; Jensen, Anna Chick

    2010-01-01

    An introduction to the chemistry of the triazine compound, melamine, is presented as well as a brief discussion of the health impacts on humans and pets when melamine contaminates milk products and pet food. Melamine has repeatedly been in the news, and its topical nature provides an excellent springboard for applications of a variety of chemical…

  8. Carry-over of melamine from feed to eggs and body tissues of laying hens.

    Science.gov (United States)

    Dong, X F; Liu, S Y; Tong, J M; Zhang, Q

    2010-10-01

    The objective of this study was to assess the carry-over of melamine from feed into eggs and body tissues of laying hens. In the first experiment, laying hens were supplied with feed added at 0, 1, 2, 5, 25, 50, and 100 mg kg(-1) of melamine for 21 days followed by a depletion period to observe the residues of melamine in eggs. In a second experiment, laying hens were allocated 0, 50, and 100 mg kg(-1) melamine to determine levels of melamine in body tissues. Melamine and cyanuric acid were simultaneously analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the diet as well as in eggs and body tissue. In the first experiment, melamine appeared in the egg within 24 h after first ingestion of the melamine at 5, 25, 50, and 100 mg kg(-1). Melamine concentration in egg reached a maximum of 2.34 mg kg(-1) within 17 days after exposure of 100 mg kg(-1) melamine, and the carry-over rate for melamine from feed to the eggs was 1.21%. In the second experiment, melamine was detected in tissues within 3 days after exposure; the maximum concentration of melamine residues occurred in the 100 mg kg(-1) group and was as follows: egg (1.83) > kidney (1.21) > breast muscle (0.86) > liver (0.70) > serum (0.42). The melamine level in egg albumen was about twice that of egg yolk. Melamine levels in laying hens decreased rapidly with withdrawal from feed, but melamine only declined to undetectable levels in the egg at day 6 and in tissues at day 4 after last ingestion of 100 mg kg(-1). It can be concluded that a pathway exists for the transmission of melamine from feed to egg and body tissues and the carry-over rate of melamine is low, and that melamine is not metabolized into cyanuric acid in laying hens. A positive relationship exists between exposure levels and eggs or tissues, but no direct relationship between the exposure time and measured levels of melamine in eggs and tissues. The current Chinese limit for melamine in feed and feed material of 2.5 mg kg(-1

  9. Experimental Evaluation of Equivalent-Fluid Models for Melamine Foam

    Science.gov (United States)

    Allen, Albert R.; Schiller, Noah H.

    2016-01-01

    Melamine foam is a soft porous material commonly used in noise control applications. Many models exist to represent porous materials at various levels of fidelity. This work focuses on rigid frame equivalent fluid models, which represent the foam as a fluid with a complex speed of sound and density. There are several empirical models available to determine these frequency dependent parameters based on an estimate of the material flow resistivity. Alternatively, these properties can be experimentally educed using an impedance tube setup. Since vibroacoustic models are generally sensitive to these properties, this paper assesses the accuracy of several empirical models relative to impedance tube measurements collected with melamine foam samples. Diffuse field sound absorption measurements collected using large test articles in a laboratory are also compared with absorption predictions determined using model-based and measured foam properties. Melamine foam slabs of various thicknesses are considered.

  10. Curing kinetics of alkyd/melamine resin mixtures

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana C.

    2009-01-01

    Full Text Available Alkyd resins are the most popular and useful synthetic resins applied as the binder in protective coatings. Frequently they are not used alone but are modified with other synthetic resins in the manufacture of the coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of coating called 'baking enamel' and it is cured through functional groups of resins at high temperatures. In this paper, curing kinetics of alkyd resins based on castor oil and dehydrated castor oil with melamine resin, has been studied by DSC method with programmed heating and in isothermal mode. The results determined from dynamic DSC curves were mathematically transformed using the Ozawa isoconversional method for obtaining the isothermal data. These results, degree of curing versus time, are in good agreement with those determined by the isothermal DSC experiments. By applying the Ozawa method it is possible to calculate the isothermal kinetic parameters for the alkyd/melamine resin mixtures curing using only calorimetric data obtained by dynamic DSC runs. Depending on the alkyd resin type and ratio in mixtures the values of activation energies of curing process of resin mixtures are from 51.3 to 114 kJ mol-1. The rate constant of curing increases with increasing the content of melamine resin in the mixture and with curing temperature. The reaction order varies from 1.12 to 1.37 for alkyd based on dehydrated castor oil/melamine resin mixtures and from 1.74 to 2.03 for mixtures with alkyd based on castor oil. Based on the results obtained, we propose that dehydrated castor oil alkyd/melamine resin mixtures can be used in practice (curing temperatures from 120 to 160°C.

  11. Corrosion Protection Performance of Polyester-Melamine Coating with Natural Wood Fiber Using EIS Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shin, PyongHwa; Shon, MinYoung [Pukyong National University, Busan (Korea, Republic of); Jo, DuHwan [POSCO, Gwangyang (Korea, Republic of)

    2016-04-15

    In the present study, polyester-melamine coating systems with natural wood fiber (NWF) were prepared and the effects of NWF on the corrosion protectiveness of the polyester-melamine coating were examined using EIS analysis. From the results, higher average surface roughness was observed with increase of NWF content. Water diffusivity and water uptake into the polyester-melamine coatings with NWF were much higher than that into the pure polyester-melamine coating. The decrease in the impedance modulus |Z| was associated with the localized corrosion on carbon steel, confirming that corrosion protection of the polyester-melamine coatings with NWF well agrees with its water transport behavior.

  12. Melamine in sojaschilfers, oorzaak van verschillen tussen laboratoria

    NARCIS (Netherlands)

    Mol, J.G.J.; Egmond, van H.J.; Jong, de J.

    2009-01-01

    In november 2008 is door het bedrijfsleven in een tweetal partijen diervoedergrondstoffen (sojaschilfers/-meel) melamine aangetroffen op niveaus tussen 40 en 800 mg/kg. Naar aanleiding hiervan heeft de VWA aan RIKILT verzocht om deze monsters (genomen door het bedrijfsleven) te analyseren op

  13. In Vitro Degradation of Melamine by Ruminal Microorganisms ...

    African Journals Online (AJOL)

    An in vitro study was conducted to determine the extent of melamine degradation in rumen liquor. Rumen liquor was collected from two ruminally cannulated Holstein cows on four separate dates, one week apart. Erlenmeyer flasks (250 mL) were prepared for incubation by adding 1000 mg of a dairy feed substrate, 100 mg ...

  14. Analytical methods for the evaluation of melamine contamination.

    Science.gov (United States)

    Cantor, Stuart L; Gupta, Abhay; Khan, Mansoor A

    2014-02-01

    There is an urgent need for the analysis of melamine in the global pharmaceutical supply chain to detect economically motivated adulteration or unintentional contamination using a simple, nondestructive analytical technique that confirms the extent of adulteration in a shorter time period. In this work, different analytical techniques (thermal analysis, X-ray diffraction, Fourier transform infrared (FT-IR), FT-Raman, and near-infrared (NIR) spectroscopy) were evaluated for their ability to detect a range of melamine levels in gelatin. While FT-IR and FT-Raman provided qualitative assessment of melamine contamination or adulteration, powder X-ray diffraction and NIR were able to detect and quantify the presence of melamine at levels as low as 1.0% w/w. Multivariate analysis of the NIR data yielded the most accurate model when three principal components were used. Data were pretreated using standard normal variate transformation to remove multiplicative interferences of scatter and particle size. The model had a root-mean-square error of calibration of 2.4 (R(2) = 0.99) and root-mean square error of prediction of 2.5 (R(2) = 0.96). The value of the paired t test for actual and predicted samples (1%-50% w/w) was 0.448 (p 5), further indicating the robustness of the model. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  15. [Investigation of typical melamine urinary stones using infrared spectra].

    Science.gov (United States)

    Si, Min-Zhen; Li, Qing-Yun; Liu, Ren-Ming; Kang, Yi-Pu; Wang, Kun-Hua; Zhang, Zhi-Guo

    2010-02-01

    A typical melamine kidney stone confirmed by some medicine expert was collected from the first people's hospital of Yunnan. The kidney stone was adequately determined by PE corporation spectra 100(with resolution of 1 cm(-1)). The stone samples for FTIR analysis were prepared using the KBr pellet technique, where 2 mg of the pretreated stone powder was mixed with 200 mg of analytical grade KBr using an agate pestle and mortar. The digital spectrum was then scanned in the mid-infrared region from 4 000 to 400 cm(-1) at room temperature. The appearing bands between 4 000 and 2 000 cm(-1) were 3 487, 3 325, 3 162 and 2 788 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 694, 1 555, 1 383, 1 340, 1 189 and 1 122 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 782, 748, 709, 624, 585, 565 and 476 cm(-1). It was found that the main constituent of calculi showed few comparability with cat kidney stone, which was from cats that died after consuming the contaminated food, and confirmed that these deposits were primarily composed of melamine and cyanuric acid compared to the IR spectra of calculi in literature. It was also found that the main constituent of calculi showed few comparability with popular kidney stone by comparison with the IR spectra of calculi in literature. The spectrum of calculi was 50% respectively similar with melamine and uric acid as compared with the IR spectrum. It was found that the main constituent of calculi was melamine itself and uric acid as compared with the IR spectra of calculi and melamine: (1 : 1), because the spectrum of calculi was 83. 3% similar to melamine and uric acid (1 : 1). The appearing bands of melamine and uric acid (1 : 1) between 4 000 and 2 000 cm(-1) were 3 469, 3 419, 3 333, 3 132, 3 026, 2 827 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 696, 1 656, 1 555, 1 489, 1 439, 1 350, 1 311, 1 198, 1 124 and 1 028 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 878, 814, 784, 745, 708, 619, 577 and

  16. Tissue deposition and residue depletion of melamine in fattening pigs following oral administration.

    Science.gov (United States)

    Wang, Wei; Chen, Hong; Yu, Bing; Mao, Xiangbing; Chen, Daiwen

    2014-01-01

    The adulteration of animal feed as well as milk products with melamine has led to concerns about the ability to establish appropriate withdrawal intervals to ensure food safety. Two experiments were conducted in this study. The first was to investigate the deposition and depletion of melamine in blood and tissues of pigs exposed to adulterated feed with high doses of melamine. A total of 500 or 1000 mg kg(-1) melamine was added to the diet for fattening pigs (initial BW = ±60.24 kg). Melamine residues were detected in tissues (brain, duodenum, liver, heart, muscle and kidney) by LC-MS/MS. Dose-dependent effects were found between melamine residual concentration and its dose in feed. Five days after the withdrawal of melamine from the diets, the residue concentration in tissues fell below 2.5 mg kg(-1). In the second experiment, blood samples were taken at different time points from fattening pigs (BW = 100 kg) fed with adulterated feed with 1000 mg kg(-1) of melamine for 42 days. Results from the pharmacokinetics analysis showed that it would take 83 h for the melamine level in plasma depleting to the safe level of 50 ng ml(-1) after an expose of 1000 mg kg(-1) melamine contaminated feed for 42 days.

  17. Comparison of the migration of melamine from melamine-formaldehyde plastics ('melaware') into various food simulants and foods themselves

    NARCIS (Netherlands)

    Bradley, E.L.; Castle, L.; Day, J.S.; Ebner, I.; Ehlert, K.; Helling, R.; Koster, S.; Leak, J.; Pfaff, K.

    2010-01-01

    A variety of melaware articles were tested for the migration of melamine into the food simulant 3% w/v acetic acid as a benchmark, and into other food simulants, beverages and foods for comparison. The results indicate that the acidity of the food simulant plays a role in promoting migration, but

  18. Method validation study on determination of melamine and cyanuric acid in food : CEN Collaborative Study 2014 : Melamine and cyanuric acid

    NARCIS (Netherlands)

    Elbers, I.J.W.; Traag, W.A.

    2014-01-01

    At the request of the European Committee for Standardization (CEN) by RIKILT a standard for the determination of melamine (MEL) and cyanuric acid (CYA) in food was described. In order to validate this new CEN method a ring trial was organized between February 2014 and July 2014. The objective is to

  19. Recent advances in the risk assessment of melamine and cyanuric acid in animal feed

    International Nuclear Information System (INIS)

    Dorne, Jean Lou; Doerge, Daniel R.; Vandenbroeck, Marc; Fink-Gremmels, Johanna; Mennes, Wim; Knutsen, Helle K.; Vernazza, Francesco; Castle, Laurence; Edler, Lutz; Benford, Diane

    2013-01-01

    Melamine can be present at low levels in food and feed mostly from its legal use as a food contact material in laminates and plastics, as a trace contaminant in nitrogen supplements used in animal feeds, and as a metabolite of the pesticide cyromazine. The mechanism of toxicity of melamine involves dose-dependent formation of crystals with either endogenous uric acid or a structural analogue of melamine, cyanuric acid, in renal tubules resulting in potential acute kidney failure. Co-exposure to melamine and cyanuric acid in livestock, fish, pets and laboratory animals shows higher toxicity compared with melamine or cyanuric acid alone. Evidence for crystal formation between melamine and other structural analogs i.e. ammelide and ammeline is limited. Illegal pet food adulterations with melamine and cyanuric acid and adulteration of milk with melamine resulted in melamine–cyanuric acid crystals, kidney damage and deaths of cats and dogs and melamine–uric acid stones, hospitalisation and deaths of children in China respectively. Following these incidents, the tolerable daily intake for melamine was re-evaluated by the U.S. Food and Drug Administration, the World Health Organisation, and the Scientific Panel on Contaminants in the Food Chain of the European Food Safety Authority (EFSA). This review provides an overview of toxicology, the adulteration incidents and risk assessments for melamine and its structural analogues. Particular focus is given to the recent EFSA risk assessment addressing impacts on animal and human health of background levels of melamine and structural analogues in animal feed. Recent research and future directions are discussed. - Highlights: ► Melamine in food and feed. ► Forms crystals in kidney with uric acid or cyanuric acid. ► Toxicity higher with cyanuric acid. ► Recent EFSA risk assessment. ► Animal and human health

  20. Recent advances in the risk assessment of melamine and cyanuric acid in animal feed

    Energy Technology Data Exchange (ETDEWEB)

    Dorne, Jean Lou, E-mail: jean-lou.dorne@efsa.europa.eu [Unit on Contaminants, European Food Safety Authority, Largo N. Palli 5/A, 43121 Parma (Italy); Doerge, Daniel R. [NCTR, Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States); Vandenbroeck, Marc [Unit on Contaminants, European Food Safety Authority, Largo N. Palli 5/A, 43121 Parma (Italy); Fink-Gremmels, Johanna [University of Utrecht (Netherlands); Mennes, Wim [RIVM, Bilthoven (Netherlands); Knutsen, Helle K. [Norwegian Institute of Public Health, Oslo (Norway); Vernazza, Francesco [Dietary and Chemical Monitoring, European Food Safety Authority, Largo N. Palli 5/A, 43121 Parma (Italy); Castle, Laurence [FERA, York (United Kingdom); Edler, Lutz [German Cancer Research Center, Heidelberg (Germany); Benford, Diane [Food Standard Agency, London (United Kingdom)

    2013-08-01

    Melamine can be present at low levels in food and feed mostly from its legal use as a food contact material in laminates and plastics, as a trace contaminant in nitrogen supplements used in animal feeds, and as a metabolite of the pesticide cyromazine. The mechanism of toxicity of melamine involves dose-dependent formation of crystals with either endogenous uric acid or a structural analogue of melamine, cyanuric acid, in renal tubules resulting in potential acute kidney failure. Co-exposure to melamine and cyanuric acid in livestock, fish, pets and laboratory animals shows higher toxicity compared with melamine or cyanuric acid alone. Evidence for crystal formation between melamine and other structural analogs i.e. ammelide and ammeline is limited. Illegal pet food adulterations with melamine and cyanuric acid and adulteration of milk with melamine resulted in melamine–cyanuric acid crystals, kidney damage and deaths of cats and dogs and melamine–uric acid stones, hospitalisation and deaths of children in China respectively. Following these incidents, the tolerable daily intake for melamine was re-evaluated by the U.S. Food and Drug Administration, the World Health Organisation, and the Scientific Panel on Contaminants in the Food Chain of the European Food Safety Authority (EFSA). This review provides an overview of toxicology, the adulteration incidents and risk assessments for melamine and its structural analogues. Particular focus is given to the recent EFSA risk assessment addressing impacts on animal and human health of background levels of melamine and structural analogues in animal feed. Recent research and future directions are discussed. - Highlights: ► Melamine in food and feed. ► Forms crystals in kidney with uric acid or cyanuric acid. ► Toxicity higher with cyanuric acid. ► Recent EFSA risk assessment. ► Animal and human health.

  1. Effects of Wet-Blending on Detection of Melamine in Spray-Dried Lactose.

    Science.gov (United States)

    Yakes, Betsy Jean; Bergana, Marti M; Scholl, Peter F; Mossoba, Magdi M; Karunathilaka, Sanjeewa R; Ackerman, Luke K; Holton, Jason D; Gao, Boyan; Moore, Jeffrey C

    2017-07-19

    During the development of rapid screening methods to detect economic adulteration, spray-dried milk powders prepared by dissolving melamine in liquid milk exhibited an unexpected loss of characteristic melamine features in the near-infrared (NIR) and Raman spectra. To further characterize this "wet-blending" phenomenon, spray-dried melamine and lactose samples were produced as a simplified model and investigated by NIR spectroscopy, Raman spectroscopy, proton nuclear magnetic resonance ( 1 H NMR), and direct analysis in real time Fourier transform mass spectrometry (DART-FTMS). In contrast to dry-blended samples, characteristic melamine bands in NIR and Raman spectra disappeared or shifted in wet-blended lactose-melamine samples. Subtle shifts in melamine 1 H NMR spectra between wet- and dry-blended samples indicated differences in melamine hydrogen-bonding status. Qualitative DART-FTMS analysis of powders detected a greater relative abundance of lactose-melamine condensation product ions in the wet-blended samples, which supported a hypothesis that wet-blending facilitates early Maillard reactions in spray-dried samples. Collectively, these data indicated that the formation of weak, H bonded complexes and labile, early Maillard reaction products between lactose and melamine contribute to spectral differences observed between wet- and dry-blended milk powder samples. These results have implications for future evaluations of adulterated powders and emphasize the important role of sample preparation methods on adulterant detection.

  2. Toxicity of melamine, an adulterant in fish feeds: experimental assessment of its effects on tilapia.

    Science.gov (United States)

    Phromkunthong, W; Nuntapong, N; Boonyaratpalin, M; Kiron, V

    2013-06-01

    Unscrupulous inclusion of melamine in fish feeds can be harmful to fish and may be hazardous to human health. An eight-week feeding trial examined the effects of melamine (inclusion levels; 5-30 g kg⁻¹ feed) on the growth performance, feed efficiency, histopathological changes and melamine residues in sex-reversed red tilapia, Oreochromis niloticus (L.) × O.mossambicus (Peters). Fish which received melamine-containing feeds grew less, utilized feeds less efficiently and performed poorly, besides exhibiting defects such as fin erosion, anorexia, sluggish swimming behaviour, paling/darkening of skin and low survival. Melamine concentration in the fish reflected its inclusion level in the feeds, and the content was higher in the viscera than in the fish fillet or whole fish. Histopathological alterations were evident in the kidney, liver and gills of fish subjected to melamine treatment - the severity of lesions corresponded to its dosage. Enlargement of renal tubules was observed in the kidney of fish fed with ≥10 g melamine kg⁻¹ feed, although, crystals were not deposited. Fish subjected to melamine insult had more prominent lesions in liver than in kidney. Toxic effects on the gills manifested as epithelial hyperplasia of the primary and secondary lamellae. The anomalies were severe at higher intake levels of melamine. © 2012 Blackwell Publishing Ltd.

  3. Isoconversional kinetic analysis of the alkyd/melamine resins curing

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana

    2013-01-01

    Full Text Available The curing reaction for the mixtures of alkyd resins based on ricinoleic acid, phthalic anhydride and three polyols (glycerin, trimethylolpropane or ethoxylated pentaerythritol with two different commercial melamine resins was investigated by differential scanning calorimetry (DSC. The curing kinetics analysis was performed using the isoconversional methods (Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Friedman. Isoconversional methods were carried out with three heating rates (5, 10 and 20°C/min in a scanning temperature range from 40 to 250°C. It was found that the curing activation energy of resin mixtures is influenced by alkyd and melamine resin type due to the catalytic effect of hydroxyl group on the reactions. The dependence of apparent curing degree on time, which was obtained by mathematical transformations of dynamic DSC data using Ozawa-Flynn-Wall method, describes well the isothermal DSC experiments.

  4. Curing kinetics of alkyd/melamine resin mixtures

    OpenAIRE

    Jovičić Mirjana C.; Radičević Radmila Ž.

    2009-01-01

    Alkyd resins are the most popular and useful synthetic resins applied as the binder in protective coatings. Frequently they are not used alone but are modified with other synthetic resins in the manufacture of the coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of coating called 'baking enamel' and it is cured through functional groups of resins at high temperatures. In this paper, curing kinetics of alkyd resins based on castor oil and dehydrated castor...

  5. 21 CFR 177.1460 - Melamine-formaldehyde resins in molded articles.

    Science.gov (United States)

    2010-04-01

    ... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1460 Melamine... melamine is made to react with not more than 3 moles of formaldehyde in water solution. (b) The resins may... polymerization reaction control agent. Phthalic acid anhydride Do. Zinc stearate For use as lubricant. (c) The...

  6. Hong Kong Chinese school children with elevated urine melamine levels: A prospective follow up study

    Directory of Open Access Journals (Sweden)

    Chu Winnie CW

    2011-05-01

    Full Text Available Abstract Background In 2008, the outbreak of kidney stones in children fed by melamine-tainted milk products in Mainland China has caused major public concern of food safety. We identified Hong Kong school children with elevated urine melamine level from a community-based school survey in 2007-08 and reviewed their clinical status in 2009. Methods In 2007-08, 2119 school children participated in a primary and secondary school survey in Hong Kong using a cluster sampling method. Urine aliquots from 502 subjects were assayed for melamine level. High urine melamine level was defined as urine melamine/creatinine ratio >7.1 μg/mmol. Subjects with high urine melamine level were invited for clinical evaluation in 2009 including urinalysis and ultrasound imaging of the urinary system. Results The age range of this subcohort was 6 - 20 years with 67% girls (335 female and 167 male subjects. The spot urine melamine/creatinine ratio of the 502 urine aliquots ranged from undetectable to 1467 μg/mmol (median 0.8 μg/mmol. Of these, 213 subjects had undetectable level (42%. We invited 47 (9% subjects with high urine melamine level for re-evaluation and one subject declined. The median duration of follow-up was 23.5 months (interquartile range: 19.8 - 30.6 months. None of the 46 subjects (28% boys, mean age 13.9 ± 2.9 years had any abnormality detected on ultrasound study of the urinary system. All subjects had stable renal function with a median urine albumin-creatinine ratio of 0.70 mg/mmol (interquartile range: 0.00 - 2.55 mg/mmol. Conclusions Hong Kong Chinese school children with high urine melamine levels appeared to have benign clinical course in the short term although a long term follow-up study is advisable in those with persistently high urine melamine level.

  7. Hong Kong Chinese school children with elevated urine melamine levels: a prospective follow up study.

    Science.gov (United States)

    Kong, Alice P S; Choi, Kai-Chow; Ho, Chung Shun; Chan, Michael H M; Wong, Chun Kwok; Liu, Eric K H; Chu, Winnie C W; Chow, Viola C Y; Lau, Joseph T F; Chan, Juliana C N

    2011-05-20

    In 2008, the outbreak of kidney stones in children fed by melamine-tainted milk products in Mainland China has caused major public concern of food safety. We identified Hong Kong school children with elevated urine melamine level from a community-based school survey in 2007-08 and reviewed their clinical status in 2009. In 2007-08, 2119 school children participated in a primary and secondary school survey in Hong Kong using a cluster sampling method. Urine aliquots from 502 subjects were assayed for melamine level. High urine melamine level was defined as urine melamine/creatinine ratio >7.1 μg/mmol. Subjects with high urine melamine level were invited for clinical evaluation in 2009 including urinalysis and ultrasound imaging of the urinary system. The age range of this subcohort was 6 - 20 years with 67% girls (335 female and 167 male subjects). The spot urine melamine/creatinine ratio of the 502 urine aliquots ranged from undetectable to 1467 μg/mmol (median 0.8 μg/mmol). Of these, 213 subjects had undetectable level (42%). We invited 47 (9%) subjects with high urine melamine level for re-evaluation and one subject declined. The median duration of follow-up was 23.5 months (interquartile range: 19.8 - 30.6 months). None of the 46 subjects (28% boys, mean age 13.9 ± 2.9 years) had any abnormality detected on ultrasound study of the urinary system. All subjects had stable renal function with a median urine albumin-creatinine ratio of 0.70 mg/mmol (interquartile range: 0.00 - 2.55 mg/mmol). Hong Kong Chinese school children with high urine melamine levels appeared to have benign clinical course in the short term although a long term follow-up study is advisable in those with persistently high urine melamine level.

  8. The assessment of melamine and cyanuric acid residues in eggs from laying hens exposed to contaminated feed

    Directory of Open Access Journals (Sweden)

    Pavel Novák

    2012-01-01

    Full Text Available The aim of this study was to monitor the carry-over of melamine and its metabolite cyanuric acid from melamine-contaminated feed administered to layers into eggs. Ten experimental Isa Brown layers (36 week of age were fed melamine-contaminated feed containing 100 mg of melamine per kg of feed. The duration of the experiment was 6 weeks. Eggs were collected during whole experiment. Analysis of eggs was done by a simple extraction of melamine and cyanuric acid residues, using a water-acetonitrile mixture and analysed by gas chromatography - triple quadrupole mass spectrometry. Melamine and cyanuric acid residues were detected in all eggs collected from the experimental layers, immediately after the first administration of melamine-contaminated feed. The mean concentrations of melamine in the egg yolk and egg white recalculated on a dry matter basis were 1.90 mg·kg-1 ± 0.158 and 10.84 mg·kg-1 ± 3.951 (P ≤ 0.01; the cyanuric acid contents were 6.54 mg·kg-1 ± 0.2.466 and 4.07 mg·kg-1 ± 0.909, respectively. Melamine and cyanuric acid were not detected in eggs from control layers. Concentrations of melamine and cyanuric acid in eggs decreased quickly after melamine feeding was stopped. Our results indicate that melamine undergoes biotransformation to cyanuric acid in the layer’s body that also passed into the eggs. The results verified the presence of distribution metabolic pathway of melamine and its easiest transfer into egg yolk. Moreover, the biotransformation of melamine into cyanuric acid in eggs of layers was confirmed.

  9. Autophagy Alleviates Melamine-Induced Cell Death in PC12 Cells Via Decreasing ROS Level.

    Science.gov (United States)

    Wang, Hui; Gao, Na; Li, Zhigui; Yang, Zhuo; Zhang, Tao

    2016-04-01

    Since melamine was illegally added to raw milk for increasing the apparent protein content, such a scandal has not been quite blown out. Previous studies showed that melamine induced apoptosis and oxidative damage in both in vivo and in vitro experiments. It is well known that autophagy is closely related to oxidative stress. In the present study, we examined whether autophagy played an important role in protecting PC12 cells, which were damaged by melamine. Immunofluorescence assay showed that melamine enhanced the number of punctuate dot, indicating the increase of autophagosomes. Western blot assay presented that melamine significantly elevated the expression level of autophagy markers including LC3-II/LC3-I ratio, beclin-1, and Atg 7. Rapamycin further enhanced the effect, whereas 3-methyadenine (3-MA) inhibited it. MTT assay exhibited that rapamycin significantly enhanced the cell viability (P PC12 cells (P cells (P PC12 cells (P cells (P PC12 cells from melamine-induced cell death via inhibiting the excessive generation of ROS. Regulating autophagy may become a new targeted therapy to relieve the damage induced by melamine.

  10. Voltamperometric Discrimination of Urea and Melamine Adulterated Skimmed Milk Powder

    Science.gov (United States)

    Hilding-Ohlsson, Astrid; Fauerbach, Jonathan A.; Sacco, Natalia J.; Bonetto, M. Celina; Cortón, Eduardo

    2012-01-01

    Nitrogen compounds like urea and melamine are known to be commonly used for milk adulteration resulting in undesired intoxication; a well-known example is the Chinese episode occurred in 2008. The development of a rapid, reliable and economic test is of relevance in order to improve adulterated milk identification. Cyclic voltammetry studies using an Au working electrode were performed on adulterated and non-adulterated milk samples from different independent manufacturers. Voltammetric data and their first derivative were subjected to functional principal component analysis (f-PCA) and correctly classified by the KNN classifier. The adulterated and non-adulterated milk samples showed significant differences. Best results of prediction were obtained with first derivative data. Detection limits in milk samples adulterated with 1% of its total nitrogen derived from melamine or urea were as low as 85.0 mg·L−1 and 121.4 mg·L−1, respectively. We present this method as a fast and robust screening method for milk adulteration analysis and prevention of food intoxication. PMID:23112709

  11. Synthesis and characterizations of melamine-based epoxy resins.

    Science.gov (United States)

    Ricciotti, Laura; Roviello, Giuseppina; Tarallo, Oreste; Borbone, Fabio; Ferone, Claudio; Colangelo, Francesco; Catauro, Michelina; Cioffi, Raffaele

    2013-09-05

    A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials.

  12. Detection and determination of Melamine in infant formula by ELISA method

    Directory of Open Access Journals (Sweden)

    A Shakerian

    2012-05-01

    Full Text Available Thirty-six samples of infant formula with different production dates and various brands were purchased from Isfahan city during 2012. The samples were assayed for the presence and quantity of melamine by ELISA screening method. According to the results, in any infant formula melamine contamination was observed above the detection limit of the kit (10 µg/L. Therefore, it was concluded that the infant formula at Isfahan retail is not considered a health hazard from the melamine contamination point of view.

  13. The content of melamine in milk based products, and milk powders analyzed by liquid chromatography mass spectrometry

    Directory of Open Access Journals (Sweden)

    Rachmawati S

    2013-03-01

    Full Text Available Melamine is a white crystal of organic compound has a molecular weight of 126.12, difficult to solve in water. Cases of illegally adding melamine in milk powder is subjected to increase the nitrogen content of milk, because melamine contains high nitrogen (66%, so when milk is tested, seems contains high protein. This paper presented data the content of melamine in products based milk, and milk powders which entered and marketed in Indonesia. Melamine analysis is done by LC- MS 2010 EV, Shimadzu. Confirmation and validation tests indicate that melamine scanning found at m/z = 127, suitable system of analysis with relative standard deviation (RSD given of 1,18% (< 2,0%. Accuracy test gave the average of 89.1% recovery, detection limit of 5 ppb and limit of quantition 7 ppb. About 91.3% samples (n = 46 collected from animal quarantine Tanjung Priok contained melamine in the range of 6.7 ppb to 61.5 ppb which is 1/49 to 1/16 times less than standard limit. Whereas about 40%, 14 out of 35 samples collected from Bandung and Jakarta supermarket was not detected of melamine, and 60% samples positive contain melamine in the range of 5,1 to 26,5 ppb (1/200 to 1/38 standard limit. However, all the samples analyzed contain melamine below the standard limit of 1 ppm determined by WHO/FAO.

  14. Detection of melamine on fractals of unmodified gold nanoparticles by surface-enhanced Raman scattering.

    Science.gov (United States)

    Roy, Pradip Kumar; Huang, Yi-Fan; Chattopadhyay, Surojit

    2014-01-01

    A simple way of detecting melamine in raw milk is demonstrated via surface-enhanced Raman spectroscopy (SERS) using fractals of bare and nonfunctionalized ~30 nm gold nanoparticles (AuNP) distributed on a solid support. The technique demonstrates the formation of AuNP fractals, from a random distribution, upon exposure to melamine, that enhance the Raman scattering cross-section to enable detection by SERS. The agglomeration, which is pronounced at higher melamine concentrations, is demonstrated directly through imaging, and the red-shift of the plasmon absorption peak of the AuNP fractal away from 530 nm by finite difference time domain (FDTD) calculations. The agglomeration results in a strong plasmon field, shown by FDTD, over the interparticle sites that enhances the Raman scattering cross-section of melamine and ensures unambiguous detection. Limit of detection of 100 ppb could be achieved reproducibly.

  15. Effect of Coversheet Materials on the Acoustic Performance of Melamine Foam

    Science.gov (United States)

    McNelis, Anne M.; Hughes, William O.

    2015-01-01

    Melamine foam is a highly absorptive material that is often used inside the payload fairing walls of a launch vehicle. This foam reduces the acoustic excitation environment that the spacecraft experiences during launch. Often, the melamine foam is enclosed by thin coversheet materials for contamination protection, thermal protection, and electrostatic discharge control. Previous limited acoustic testing by NASA Glenn Research Center has shown that the presence of a coversheet material on the melamine foam can have a significant impact on the absorption coefficient and the transmission loss. As a result of this preliminary finding a more extensive acoustic test program using several different coversheet materials on melamine foam was performed. Those test results are summarized in this paper. Additionally, a method is provided to use the acoustic absorption and transmission loss data obtained from panel level testing to predict their combined effect for the noise reduction of a launch vehicle payload fairing.

  16. Melamine and its derivatives in dog and cat urine: An exposure assessment study.

    Science.gov (United States)

    Karthikraj, Rajendiran; Bollapragada, Rasya; Kannan, Kurunthachalam

    2018-03-19

    Melamine is a nitrogen-containing organic compound that is used in a wide range of products, including paints, plastics, and paper, as a flame retardant. A few studies have reported the occurrence of melamine and its derivatives in pet food, following a number of deaths of cats and dogs from kidney failure in 2007, which was attributed to melamine contamination in ingredients used in pet food. Nevertheless, studies that report the occurrence of melamine and its derivatives in pet urine are scarce. In this study, we measured melamine and its derivatives (i.e., ammeline, ammelide, and cyanuric acid) in dog (n = 30) and cat (n = 30) urine collected from Albany, New York, USA, during March through July 2017. The mean (±SD) concentrations of melamine, ammeline, ammelide, and cyanuric acid in dog urine were 21.1 ± 51.2, 2.3 ± 3.8, 9.9 ± 1 0.4, and 79.0 ± 105 ng/mL, respectively; the corresponding concentrations in cats were 21.4 ± 26.1, 1.2 ± 2.5, 6.1 ± 3.9, and 105 ± 94.6 ng/mL, respectively. No significant difference was observed in urinary concentrations of melamine derivatives between cats and dogs. Age and gender were important determinants of the concentrations of the target chemicals in cats and dogs. Cumulative daily intake of melamine and its derivatives was calculated on the basis of urinary concentrations and was found to be 10-500-fold below the tolerable daily intake. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Quantitative detection of melamine based on terahertz time-domain spectroscopy

    Science.gov (United States)

    Zhao, Xiaojing; Wang, Cuicui; Liu, Shangjian; Zuo, Jian; Zhou, Zihan; Zhang, Cunlin

    2018-01-01

    Melamine is an organic base and a trimer of cyanamide, with a 1, 3, 5-triazine skeleton. It is usually used for the production of plastics, glue and flame retardants. Melamine combines with acid and related compounds to form melamine cyanurate and related crystal structures, which have been implicated as contaminants or biomarkers in protein adulterations by lawbreakers, especially in milk powder. This paper is focused on developing an available method for quantitative detection of melamine in the fields of security inspection and nondestructive testing based on THz-TDS. Terahertz (THz) technology has promising applications for the detection and identification of materials because it exhibits the properties of spectroscopy, good penetration and safety. Terahertz time-domain spectroscopy (THz-TDS) is a key technique that is applied to spectroscopic measurement of materials based on ultrafast femtosecond laser. In this study, the melamine and its mixture with polyethylene powder in different consistence are measured using the transmission THz-TDS. And we obtained the refractive index spectra and the absorption spectrum of different concentrations of melamine on 0.2-2.8THz. In the refractive index spectra, it is obvious to see that decline trend with the decrease of concentration; and in the absorption spectrum, two peaks of melamine at 1.98THz and 2.28THz can be obtained. Based on the experimental result, the absorption coefficient and the consistence of the melamine in the mixture are determined. Finally, methods for quantitative detection of materials in the fields of nondestructive testing and quality control based on THz-TDS have been studied.

  18. Melamine-bridged alkyl resorcinol modified urea - formaldehyde resin for bonding hardwood plywood

    Science.gov (United States)

    Chung-Yun Hse; Mitsuo Higuchi

    2010-01-01

    A powdery product was obtained by the reaction of methylolated melamine with alkyl resorcinols to form melamine-bridged alkyl resorcinols (MARs). The effects of the addition of this powder on the bonding strength and formaldehyde emission of urea–formaldehyde (UF) resins were investigated. Three types of UF resins with a formaldehyde/urea molar ratio of 1.3 synthesized...

  19. Modulation of the Singlet Oxygen Generation from the Double Strand DNA-SYBR Green I Complex Mediated by T-Melamine-T Mismatch for Visual Detection of Melamine.

    Science.gov (United States)

    Hu, Hao; Zhang, Jinyi; Ding, Yu; Zhang, Xinfeng; Xu, Kailai; Hou, Xiandeng; Wu, Peng

    2017-05-02

    Singlet oxygen ( 1 O 2 ), generated via photosensitization, has been proved to oxidize chromogenic substrates with neither H 2 O 2 oxidation nor enzyme (horseradish peroxidase, HRP) catalysis. Of the various methods for modulation of the 1 O 2 generation, DNA-controlled photosensitization received great attention. Therefore, integration of the formation/deformation DNA structures with DNA-controlled photosensitization will be extremely appealing in visual biosensor developments. Here, the stable melamine-thymine complex was explored in combination with DNA-controlled photosensitization for visual detection of melamine. A T-rich single stand DNA was utilized as the recognition unit. Upon the formation of the T-M-T complex, double stand DNA was formed, which was ready for the binding of SYBR Green I and activated the photosensitization. Subsequent oxidation of TMB allowed visual detection of melamine in dairy products, with spike-recoveries ranging from 94% to 106%.

  20. Decomposition mechanism of melamine borate in pyrolytic and thermo-oxidative conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hoffendahl, Carmen; Duquesne, Sophie; Fontaine, Gaëlle; Bourbigot, Serge, E-mail: serge.bourbigot@ensc-lille.fr

    2014-08-20

    Highlights: • Decomposition of melamine borate in pyrolytic and thermo-oxidative conditions was investigated. • With increasing temperature, orthoboric acid forms boron oxide releasing water. • Melamine decomposes evolving melamine, ammonia and other fragments. • Boron oxide is transformed into boron nitride and boron nitride-oxide structures through presence of ammonia. - Abstract: Decomposition mechanism of melamine borate (MB) in pyrolytic and thermo-oxidative conditions is investigated in the condensed and gas phases using solid state NMR ({sup 13}C and {sup 11}B), X-ray photoelectron spectroscopy (XPS), pyrolysis-gas chromatography–mass spectrometry (py-GCMS) and thermogravimetric analysis coupled with a Fourier transform infrared spectrometer (TGA–FTIR). It is evidenced that orthoboric acid dehydrates to metaboric and then to boron oxide. The melamine is partially sublimated. At the same time, melamine condensates, i.e., melem and melon are formed. Melon is only formed in thermo-oxidative conditions. At higher temperature, melem and melon decompose releasing ammonia which reacts with the boron oxide to form boron nitride (BN) and BNO structures.

  1. Survey of counterfeit melamine tableware available on the market in Thailand, and its migration.

    Science.gov (United States)

    Poovarodom, N; Tangmongkollert, P; Jinkarn, T; Chonhenchob, V

    2011-02-01

    A simple measurement of sample density by adopting the principles of buoyancy could help screen counterfeit melamine ware if the density was below 1.50 g cm⁻³. However, samples with a density exceeding 1.50 g cm⁻³ were not necessarily made from melamine formaldehyde. FTIR analysis showed that all counterfeit products were made of urea formaldehyde and coated on the food-contact side with melamine formaldehyde, a tactic probably intended to cover up the true product features. The overall migration of real and counterfeit melamine samples complied with both European Union and Thai regulations, as the exposure layers in both cases were melamine formaldehyde. Formaldehyde migration failed to comply with Thai standards, but this was not the case for European Union standards. However, the results showed a significant inconsistency between individual items of the same brand and between individual exposures of the same test specimen. This indicated the inherent inhomogeneity between individual items, which mainly resulted from the manufacturing process: for instance, insufficient temperature and time to obtain complete polycondensation of monomers. Therefore, it is recommended that constant surveillance be conducted on melamine articles available in the marketplace in terms of quality and safety.

  2. Effects of the Adulteration Technique on the Near-Infrared Detection of Melamine in Milk Powder.

    Science.gov (United States)

    Scholl, Peter F; Bergana, Marti Mamula; Yakes, Betsy Jean; Xie, Zhuohong; Zbylut, Steven; Downey, Gerard; Mossoba, Magdi; Jablonski, Joseph; Magaletta, Robert; Holroyd, Stephen E; Buehler, Martin; Qin, Jianwei; Hurst, William; LaPointe, Joseph H; Roberts, Dean; Zrybko, Carol; Mackey, Andrew; Holton, Jason D; Israelson, Greg A; Payne, Anitra; Kim, Moon S; Chao, Kuanglin; Moore, Jeffrey C

    2017-07-19

    The United States Pharmacopeial Convention has led an international collaborative project to develop a toolbox of screening methods and reference standards for the detection of milk powder adulteration. During the development of adulterated milk powder reference standards, blending methods used to combine melamine and milk had unanticipated strong effects on the near-infrared (NIR) spectrum of melamine. The prominent absorbance band at 1468 nm of melamine was retained when it was dry-blended with skim milk powder but disappeared in wet-blended mixtures, where spray-dried milk powder samples were prepared from solution. Analyses using polarized light microscopy, Raman spectroscopy, dielectric relaxation spectroscopy, X-ray diffraction, and mass spectrometry indicated that wet blending promoted reversible and early Maillard reactions with lactose that are responsible for differences in melamine NIR spectra between wet- and dry-blended samples. Targeted detection estimates based solely on dry-blended reference standards are likely to overestimate NIR detection capabilities in wet-blended samples as a result of previously overlooked matrix effects arising from changes in melamine hydrogen-bonding status, covalent complexation with lactose, and the lower but more homogeneous melamine local concentration distribution produced in wet-blended samples. Techniques used to incorporate potential adulterants can determine the suitability of milk reference standards for use with rapid detection methods.

  3. Supramolecular intermediates in the synthesis of polymeric carbon nitride from melamine cyanurate

    Energy Technology Data Exchange (ETDEWEB)

    Dante, Roberto C., E-mail: rcdante@yahoo.com [Facultad de Mecánica, Escuela Politécnica Nacional (EPN), Ladrón de Guevara E11-253, Quito (Ecuador); Sánchez-Arévalo, Francisco M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de Mexico, Apdo. Postal 70-360, Cd. Universitaria, Mexico D.F. 04510 (Mexico); Chamorro-Posada, Pedro [Dpto. de Teoría de la Señal y Comunicaciones e IT, Universidad de Valladolid, ETSI Telecomunicación, Paseo Belén 15, 47011 Valladolid (Spain); Vázquez-Cabo, José [Dpto. de Teoría de la Señal y Comunicaciones, Universidad de Vigo, ETSI Telecomunicación, Lagoas Marcosende s/n, Vigo (Spain); Huerta, Lazaro [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de Mexico, Apdo. Postal 70-360, Cd. Universitaria, Mexico D.F. 04510 (Mexico); Lartundo-Rojas, Luis [Centro de Nanociencias y Micro y Nanotecnologías—IPN, Luis Enrique Erro s/n, U. Prof. Adolfo López Mateos, 07738 Ciudad de Mexico, Distrito Federal (Mexico); Santoyo-Salazar, Jaime [Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV-IPN, Apdo. Postal 14-740, Mexico D.F. 07360 (Mexico); and others

    2015-03-15

    The adduct of melamine and cyanuric acid (MCA) was used in past research to produce polymeric carbon nitride and precursors. The reaction yield was considerably incremented by the addition of sulfuric acid. The polymeric carbon nitride formation occurs around 450 °C at temperatures above the sublimation of the adduct components, which occurs around 400 °C. In this report the effect of sulfuric acid on MCA was investigated. It was found that the MCA rosette supramolecular channel structures behave as a solid solvent able to host small molecules, such as sulfuric acid, inside these channels and interact with them. Therefore, the sulfuric acid effect was found to be close to that of a solute that causes a temperature increment of the “solvent sublimation” enough to allowing the formation of polymeric carbon nitride to occur. Sulfate ions are presumably hosted in the rosette channels of MCA as shown by simulations. - Graphical abstract: The blend of melamine cyanurate and sulfuric acid behaves like a solution so that melamine cyanurate decomposition is shifted to temperatures high enough to react and form polymeric carbon nitride. - Highlights: • The adduct of melamine and cyanuric acid behaves as a solid solvent. • The blend of sulfuric acid and melamine cyanurate behaves like a solution. • Melamine cyanurate decomposition is shifted to higher temperatures by sulfuric acid. • The formation of polymeric carbon nitride occurs for these higher temperatures.

  4. Succinic acid functionalized silver nanoparticles (Suc-Ag NPs) for colorimetric sensing of melamine

    Science.gov (United States)

    Rajar, Kausar; Sirajuddin; Balouch, Aamna; Bhanger, M. I.; Shah, Muhammad Tariq; Shaikh, Tayyaba; Siddiqui, Samia

    2018-03-01

    In this study, a quantitative colorimetric sensing strategy is developed for the rapid, sensitive and selective determination of melamine. The sensing system relies on the application of succinic acid as a selective recognition probe functionalized over Ag NPs. The synthesized Ag NPs were modified with cysteamine to induce positively charged atmosphere which allowed easy and favorable functionalization of succinic acid. The di-carboxyl nature of succinic acid enabled its binding to both cysteamine and melamine. The strong and favorable linkage between succinic acids carbonyl and amine moieties of melamine triggered aggregation of silver NPs producing a significant shift in the measured absorption excitation. This change in the excitation along with the colorimetric response was found linearly proportional to the melamine concentration in the range of 0.1-1.2 μM. The developed sensor system is simple and unlike electrostatic attraction based sensor system utilize selective linkage for the recognition of melamine. In addition to this, the developed optical probe can efficiently be used for the determination of melamine in milk samples.

  5. [Quantitative determination of melamine by fluorescence spectroscopy and radial basis function neural networks].

    Science.gov (United States)

    Chen, Guo-qing; Wei, Bai-lin; Wang, Jun; Wu, Ya-min; Gao, Shu-mei; Kong, Yan; Zhu, Tuo

    2010-01-01

    Based on the experimental study, it was found that melamine solution excited by UV light can generate a strong fluorescence. The fluorescence spectrum is within a range from 310 to 600 nm, the peak wavelength of the fluorescence is about 420 nm, and the relationship between fluorescence intensity and melamine solution concentration is nonlinear. A method for the determination of melamine solution concentration was presented, which was based on fluorescence spectroscopy and radial basis function neural networks. For each sample, 30 emission wavelength values were selected, the fluorescence intensity corresponding to the selected wavelength was used as the network data, and a radial basis function neural network was trained and constructed. The trained radial basis function neural network was employed to predict the melamine solution concentration in five kinds of samples, and the relative errors of the results were 0.93%, 0.09%, 0.31%, 1.55% and 4.61%, respectively. The results show that this method can determine the content of melamine quickly and accurately. The whole research outcomes will provide a new method for determining the content of melamine and food safety supervision.

  6. Evaluation of subchronic toxicity of pet food contaminated with melamine and cyanuric acid in rats.

    Science.gov (United States)

    Chen, Kun-Chao; Liao, Chen-Wei; Cheng, Fen-Pang; Chou, Chi-Chung; Chang, Shih-Chien; Wu, Jhaol-Huei; Zen, Jyh-Myng; Chen, Yng-Tay; Liao, Jiunn-Wang

    2009-12-01

    Outbreaks of food-associated renal failure in pets occurred in Asia and the United States of America in 2004 and 2007. They were related to the combined intoxication of cyanuric acid and melamine. Our aims were to investigate cyanuric acid and melamine contamination of pet food and to examine subchronic toxicity in rats. Levels of 10%, 20%, 50%, and 50%-100% (w/w) of contaminated pet food were fed to rats for three months. Analytical results revealed that the tainted food contained significant levels of cyanuric acid and melamine in a ratio of 1:6.8. Rats fed the diet of 50%-100% for three months exhibited elevated serum blood urea nitrogen and creatinine, as well as dose-dependent melamine/cyanuric acid crystal-induced nephrotoxicity. The melamine/cyanuric acid crystals of various sizes were mixed with necrotic cell debris and inflammatory cells, accompanied by tubular dilation and interstitial fibrosis. The immunohistochemistry index of proliferative cellular nuclear antigen and osteopontin in the kidney of the 50%-100% group were elevated, indicating regeneration of renal cells and the formation of crystals. In conclusion, the combination ratio of cyanuric acid to melamine and the acidic urine content were two factors that, upon repeated exposure, determined the severity of the nephrotoxicity.

  7. Supramolecular intermediates in the synthesis of polymeric carbon nitride from melamine cyanurate

    International Nuclear Information System (INIS)

    Dante, Roberto C.; Sánchez-Arévalo, Francisco M.; Chamorro-Posada, Pedro; Vázquez-Cabo, José; Huerta, Lazaro; Lartundo-Rojas, Luis; Santoyo-Salazar, Jaime

    2015-01-01

    The adduct of melamine and cyanuric acid (MCA) was used in past research to produce polymeric carbon nitride and precursors. The reaction yield was considerably incremented by the addition of sulfuric acid. The polymeric carbon nitride formation occurs around 450 °C at temperatures above the sublimation of the adduct components, which occurs around 400 °C. In this report the effect of sulfuric acid on MCA was investigated. It was found that the MCA rosette supramolecular channel structures behave as a solid solvent able to host small molecules, such as sulfuric acid, inside these channels and interact with them. Therefore, the sulfuric acid effect was found to be close to that of a solute that causes a temperature increment of the “solvent sublimation” enough to allowing the formation of polymeric carbon nitride to occur. Sulfate ions are presumably hosted in the rosette channels of MCA as shown by simulations. - Graphical abstract: The blend of melamine cyanurate and sulfuric acid behaves like a solution so that melamine cyanurate decomposition is shifted to temperatures high enough to react and form polymeric carbon nitride. - Highlights: • The adduct of melamine and cyanuric acid behaves as a solid solvent. • The blend of sulfuric acid and melamine cyanurate behaves like a solution. • Melamine cyanurate decomposition is shifted to higher temperatures by sulfuric acid. • The formation of polymeric carbon nitride occurs for these higher temperatures

  8. Plasmid Localization and Organization of Melamine Degradation Genes in Rhodococcus sp. Strain Mel

    Science.gov (United States)

    Dodge, Anthony G.; Wackett, Lawrence P.

    2012-01-01

    Rhodococcus sp. strain Mel was isolated from soil by enrichment and grew in minimal medium with melamine as the sole N source with a doubling time of 3.5 h. Stoichiometry studies showed that all six nitrogen atoms of melamine were assimilated. The genome was sequenced by Roche 454 pyrosequencing to 13× coverage, and a 22.3-kb DNA region was found to contain a homolog to the melamine deaminase gene trzA. Mutagenesis studies showed that the cyanuric acid hydrolase and biuret hydrolase genes were clustered together on a different 17.9-kb contig. Curing and gene transfer studies indicated that 4 of 6 genes required for the complete degradation of melamine were located on an ∼265-kb self-transmissible linear plasmid (pMel2), but this plasmid was not required for ammeline deamination. The Rhodococcus sp. strain Mel melamine metabolic pathway genes were located in at least three noncontiguous regions of the genome, and the plasmid-borne genes encoding enzymes for melamine metabolism were likely recently acquired. PMID:22210223

  9. Colorimetric detection of melamine based on p-chlorobenzenesulfonic acid-modified AuNPs

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianfang; Huang, Pengcheng; Wu, Fangying, E-mail: fywu@ncu.edu.cn [Nanchang University, College of Chemistry (China)

    2016-06-15

    A highly selective and sensitive method is developed for colorimetric detection of melamine using gold nanoparticles (AuNPs) functionalized with p-chlorobenzenesulfonic acid. The addition of melamine induced the aggregation of AuNPs, as evidenced from the morphological characterizations and the color changed from red wine to blue, which could also be monitored by the UV–visible spectrometer and even naked eyes. This process caused a significant increase in the absorbance ratio (A{sub 650nm}/A{sub 520nm}) of p-chlorobenzenesulfonic acid–AuNPs. Under optimized conditions, the system exhibited a linear response to melamine in the range of 6.0 × 10{sup −7}–1.5 × 10{sup −6} mol L{sup −1} with a correlation coefficient of 0.997, and the limit of detection can even be 2.3 nM, which was much lower than some other methods and the safe limits (20 μM in both the USA and EU, 8.0 μM for infant formula in China, 1.2 μM in the CAC (Codex Alimentarius Commission) review for melamine in liquid infant formula). More importantly, the developed method presented excellent tolerance to coexisting common metal ions such as Ca{sup 2+}, Zn{sup 2+}, whose concentration is 1000 times of melamine, so that it had been applied to the analysis of melamine in liquid milk and milk powder with the recovery of 97.0–101 % and 100–103 %, respectively, indicating that the proposed method is quite a highly effective means to determine melamine in milk products.

  10. An ultrasensitive method for the determination of melamine using cadmium telluride quantum dots as fluorescence probes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiafei; Li, Jin; Kuang, Huiyan; Feng, Lei; Yi, Shoujun; Xia, Xiaodong; Huang, Haowen [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, Hunan University of Science and Technology, Xiangtan 411201 (China); Chen, Yong; Tang, Chunran [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Zeng, Yunlong, E-mail: yunlongzeng1955@126.com [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, Hunan University of Science and Technology, Xiangtan 411201 (China); State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-11-13

    Graphical abstract: Melamine takes place of the TGA on the surface of TGA-CdTe QDs with negative charge to form melamine coated QDs changing the surface charge of the QDs, resulting the fluorescence quenched as the QDs aggregation occurred by electrostatic attraction of the two opposite charged nanocrystals. -- Highlights: •An ultrasensitive and selective method for the determination of melamine was developed at pH 11.0. •The selectivity of the method was improved. •The sensitivity of the method enhanced obviously as the CdTe QDs have higher QYs at pH 11. •The sensitivity and linear range for the analysis are size dependent using QDs PL probes. •Melamine takes the place of TGA resulting fluorescence quenched of QDs. -- Abstract: An ultrasensitive and simple method for the determination of melamine was developed based on the fluorescence quenching of thioglycolic acid (TGA) capped CdTe quantum dots (QDs) at pH 11.0. In strong alkaline aqueous solution, the selectivity of the method has been greatly improved due to most heavy metal ions show no interference as they are in the precipitation form or in their anion form. Furthermore, CdTe quantum dots have higher quantum yields at higher pH. The method has a wider concentration range and lower detection limit. The influence factors on the determination of melamine were investigated and the optimum conditions were determined. Under optimum conditions, the fluorescence intensity change of TGA coated CdTe quantum dots was linearly proportional to melamine over a concentration range from 1.0 × 10{sup −11} to 1.0 × 10{sup −5} mol L{sup −1} with a correlation coefficient of 0.9943 and a detection limit of 5 × 10{sup −12} mol L{sup −1}. The mechanism of fluorescence quenching of the QDs has been proposed based on the infrared spectroscopy information and electrophoresis experiments in presence of melamine under alkaline condition. The proposed method was employed to detect trace melamine in milk powder

  11. Identification and Quantitation of Melamine in Milk by Near-Infrared Spectroscopy and Chemometrics

    Directory of Open Access Journals (Sweden)

    Tong Wu

    2016-01-01

    Full Text Available Melamine is a nitrogen-rich substance and has been illegally used to increase the apparent protein content in food products such as milk. Therefore, it is imperative to develop sensitive and reliable analytical methods to determine melamine in human foods. Current analytical methods for melamine are mainly chromatography-based methods, which are time-consuming and expensive and require complex pretreatment and well-trained technicians. The present paper investigated the feasibility of using near-infrared (NIR spectroscopy and chemometrics for identifying and quantifying melamine in liquor milk. A total of 75 samples were prepared. Uninformative variable elimination-partial least square (UVE-PLS and partial least squares-discriminant analysis (PLS-DA were used to construct quantitative and qualitative models, respectively. Based on the ratio of performance to standard deviate (RPD, UVE-PLS model with 3 components resulted in a better solution. The PLS-DA model achieved an accuracy of 100% and outperformed the optimal reference model of soft independent modeling of class analogy (SIMCA. Such a method can serve as a potential tool for rapid screening of melamine in milk products.

  12. Excited-State Dynamics of Melamine and Its Lysine Derivative Investigated by Femtosecond Transient Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yuyuan Zhang

    2016-11-01

    Full Text Available Melamine may have been an important prebiotic information carrier, but its excited-state dynamics, which determine its stability under UV radiation, have never been characterized. The ability of melamine to withstand the strong UV radiation present on the surface of the early Earth is likely to have affected its abundance in the primordial soup. Here, we studied the excited-state dynamics of melamine (a proto-nucleobase and its lysine derivative (a proto-nucleoside using the transient absorption technique with a UV pump, and UV and infrared probe pulses. For melamine, the excited-state population decays by internal conversion with a lifetime of 13 ps without coupling significantly to any photochemical channels. The excited-state lifetime of the lysine derivative is slightly longer (18 ps, but the dominant deactivation pathway is otherwise the same as for melamine. In both cases, the vast majority of excited molecules return to the electronic ground state on the aforementioned time scales, but a minor population is trapped in a long-lived triplet state.

  13. Rapid detection of melamine adulteration in dairy milk by SB-ATR-Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Jawaid, Sana; Talpur, Farah N; Sherazi, S T H; Nizamani, Shafi M; Khaskheli, Abid A

    2013-12-01

    Melamine is a nitrogenous chemical substance used principally as a starting material for the manufacture of synthetic resins. Due to its very high proportion of nitrogen melamine has been added illegitimately to foods and feeds to increase the measured protein content, which determines the value of the product. These issues prompted private as well as governmental laboratories to develop methods for the analysis of melamine in a wide variety of food products and ingredients. Owing to this fact present study is aimed to use single bounce attenuated total reflectance (SB-ATR) Fourier transform infrared spectroscopy (FTIR) method as an effective rapid tool for the detection and quantification of melamine in milk (liquid and powder). Partial least-squares (PLS) models were established for correlating spectral data to melamine concentration with R(2)>0.99, and RMSEC 0.370. Linear calibration curves were obtained over the calibration range of 25-0.0625%. The LOD and LOQ of the method was 0.00025% (2.5 ppm) and 0.0015% (15 ppm) respectively. Proposed SB-ATR-FTIR method requires little or no sample preparation with an assay time of 1-2 min. Copyright © 2013. Published by Elsevier Ltd.

  14. Effect of melamine foam cleaning on the surface condition of composite resin artificial teeth.

    Science.gov (United States)

    Tanaka, Rika; Kurogi, Tadafumi; Murata, Hiroshi

    2013-12-01

    The purpose of this study was to examine the abrasive and cleaning effects of melamine foam and other cleaning agents on the surfaces of composite resin artificial tooth specimens. A stained composite resin artificial tooth in a used denture was cleaned using a denture brush and melamine foam, and the stain removal effect was evaluated macroscopically. Next, 5 types of cleaning material (fourfold-compression melamine foam, MEL; brush with water, BRU; denture dentifrice without abrasive, POL; denture dentifrice with abrasive, TAF; conventional dentifrice, AQU) and 15 plate-shaped specimens made of composite resin for artificial teeth were used for wear tests. The surface roughness was measured using a laser scanning microscope. Furthermore, the surface properties were observed using a digital microscope. Surface roughness data were analyzed by two-way ANOVA followed by Tukey's test. Artificial tooth stains that could not be removed by brushing became removable using melamine foam. With regard to surface roughness in the context of the wear test, significant differences were not indicated between MEL and POL, whereas BRU-, TAF-, and AQU-treated specimens showed significantly increased surface roughness (p teeth. Traces of wear were not observed in specimens treated with melamine foam and the denture dentifrice not containing abrasives. It was suggested that these two materials would be desirable and useful to use for composite resin tooth cleaning. © 2013 by the American College of Prosthodontists.

  15. Analysis of cocondensation of melamine and urea through carbon 13 enriched formaldehyde with C-13 nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Bunichiro Tomita; Chung-Yun Hse

    1995-01-01

    The urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-ureaformaldehyde (MUF) cocondensed resins were synthesized using the labeling method with 13C enriched formaldehyde under neutral conditions and their 13C-NMR (nuclear magnetic resonance) spectra were analyzed. The remarkable down-field...

  16. Analyses of cocondensation of melamine and urea through carbon 13 enriched formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Tomita Bunchiro; Chung-Yun Hse

    1995-01-01

    The urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins were synthesized using the labeling method with 13C enriched formaldehyde unde neutral conditions and their 13C-NMR (nuclear magnetic resonance) spectra were analyzed. The remarkable down-field...

  17. Analysis on cocondensation of melamine and urea through carbon 13 enriched formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Bunichiro Tomita; Chung-Yun Hse

    1995-01-01

    The urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins were synthesized using the labeling method of 13C enriched formaldehyde udner neutral conditions and their 13C-NMR (nuclear magnetic resonance) spectra were analyzed. The remarkable down-field shifts...

  18. Risks associated with melamine and related triazine contamination of food

    Science.gov (United States)

    Baynes, RE; Riviere, JE

    2009-01-01

    Recent adulteration of milk products with melamine (ME) in several countries caused adverse health effects and even deaths in infants. Earlier, in 2007, contamination of pet food with ME and its related contaminants was associated with many clinical cases of canine and feline nephrotoxicity, and in some cases mortality. ME is a triazine compound that is often detected with other triazine analogs such as cyanuric acid. As is the custom in some livestock operations, the contaminated pet food was mixed with feed intended for the swine and poultry industry. This practice has raised several questions as to whether ME and its related triazines would adversely affect the health of these food animals, and whether meat products derived from swine and poultry could contain high-enough levels of these contaminants to warrant public health concern. Data for this review article were obtained from recent research efforts in our laboratory, peer-reviewed publications cited in PubMed, and information available at USDA, US FDA, and WHO websites. The primary issues discussed are related to (1) the chemistry and interactions between ME and its triazine analogs; (2) reported animal and human exposures with possible pathways through which ME can enter the human food chain; (3) mammalian toxicology; (4) comparative pharmacokinetics (PK) and modeling strategies used to predict residue levels; and (5) emerging issues and management strategies. PMID:22460395

  19. Contact allergic dermatitis from melamine formaldehyde resins in a patient with a negative patch-test reaction to formaldehyde.

    Science.gov (United States)

    García Gavin, Juan; Loureiro Martinez, Manuel; Fernandez-Redondo, Virginia; Seoane, Maria-José; Toribio, Jaime

    2008-01-01

    Melamine paper is a basic material used in the furniture industry for home and office interiors. Contact allergic dermatitis from melamine formaldehyde resins (MFRs) should be considered in patients who work on melamine paper impregnation lines. We report a case of a 28-year-old female plywood worker who developed eczema on the dorsal side of her hands and wrists after 2 years of working on the melamine paper impregnation line. She had a relevant positive patch-test reaction to MFR, with a negative reaction to formaldehyde. Contact dermatitis due to MFR is not common, and it is usually related to products that are not fully cured or to close contact with intermediate products on the assembly line. Formaldehyde release from MFR can explain most of the positive responses. To our knowledge, this is the first report of MFR contact allergic dermatitis in a worker on a melamine paper impregnation line.

  20. Designing of cardanol based polyol and its curing kinetics with melamine formaldehyde resin.

    Science.gov (United States)

    Balgude, Dinesh Bapurao; Sabnis, Anagha Shyamsunder; Ghosh, Swapan Kumar

    2017-01-01

    Commercially used industrial baking enamels consist of alkyd or polyester resin with melamine formaldehyde. These resins are mainly derived from fossil resources. Considering growing environmental legislation regarding use of petroleum based raw materials, utilization of renewable resources to synthesize various chemistries can be the only obvious option as far as academia and industries are concerns. The present work deals with exploration of one of the natural resources (Cardanol) for polyol synthesis, its characterization (FTIR and NMR) and its curing behavior with melamine formaldehyde resin by differential scanning calorimetry (DSC). The optimized formulations from DSC study were further evaluated for general coating properties to study the suitability of developed polyol for industrial coating application. The experimental studies revealed that melamine content in the curing mixtures and thereby developed crosslinking density played an important role in deciding the coatings properties.

  1. Analysis of melamine and analogs in complex matrices: Advances and trends.

    Science.gov (United States)

    Wang, Tingting; Ma, Junfeng; Chen, Yihui; Li, Ying; Zhang, Lihua; Zhang, Yukui

    2017-01-01

    The analysis of melamine and its analogs is of increasing research interest. Owing to their high nitrogen content and low price, they were deliberately added to artificially enhance protein concentration in a number of different types of human and animal food sources. In addition, environmental water might also be contaminated by melamine due to its use in the chemical industry and the degradation of the pesticide cyromazine. Herein we provide a detailed overview of recently developed materials and techniques for the analysis of melamine and its analogs in complex matrices, especially in dairy products (e.g., milk and powdered milk) and environmental water. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. DNA–melamine hybrid molecules: from self-assembly to nanostructures

    Directory of Open Access Journals (Sweden)

    Rina Kumari

    2015-06-01

    Full Text Available Single-stranded DNA–melamine hybrid molecular building blocks were synthesized using a phosphoramidation cross-coupling reaction with a zero linker approach. The self-assembly of the DNA–organic hybrid molecules was achieved by DNA hybridization. Following self-assembly, two distinct types of nanostructures in the form of linear chains and network arrays were observed. The morphology of the self-assembled nanostructures was found to depend on the number of DNA strands that were attached to a single melamine molecule.

  3. PRODUCTION OF HIGH DENSITY PARTICLEBOARD USING MELAMINE-UREA-FORMALDEHYDE RESIN

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2005-12-01

    Full Text Available This research was developed aiming to evaluate the effects of board density and melamine-urea-formaldehyde resin onthe properties of particleboard for semi-structural applications. The boards were manufactured with nominal density of 0.65 g/cm³and 0.90 g/cm³ using urea-formaldehyde resin as control and melamine-urea-formaldehyde. The results showed a better dimensionallystability and mechanical properties of the boards manufactured with higher density and MUF resin content. The fine furnish usedfor external layer of particleboard in the industrial process, could be used for high density homogeneous board to semi-strucuturaluses, such as flooring applications.

  4. Colorimetric method for the detection of melamine using in-situ formed silver nanoparticles via tannic acid

    Science.gov (United States)

    Alam, Md. Fazle; Laskar, Amaj Ahmed; Ahmed, Shahbaz; Shaida, Mohd. Azfar; Younus, Hina

    2017-08-01

    Melamine toxicity has recently attracted worldwide attention as it causes renal failure and the death of humans and animals. Therefore, developing a simple, fast and sensitive method for the routine detection of melamine is the need of the hour. Herein, we have developed a selective colorimetric method for the detection of melamine in milk samples based upon in-situ formation of silver nanoparticles (AgNPs) via tannic acid. The AgNPs thus formed were characterized by UV-Visible spectrophotometer, transmission electron microscope (TEM), zetasizer and dynamic light scattering (DLS). The AgNPs were used to detect melamine under in vitro condition and in raw milk spiked with melamine. Under optimal conditions, melamine could be selectively detected in vitro within the concentration range of 0.05-1.4 μM with a limit of detection (LOD) of 0.01 μM, which is lower than the strictest melamine safety requirement of 1 ppm. In spiked raw milk, the recovery percentage range was 99.5-106.5% for liquid milk and 98.5-105.5% for powdered milk. The present method shows extreme selectivity with no significant interference with other substances like urea, glucose, glycine, ascorbic acid etc. This assay method does not utilize organic cosolvents, enzymatic reactions, light sensitive dye molecules and sophisticated instrumentation, thereby overcoming some of the limitations of the other conventional methods.

  5. Quantitative analysis of melamine in milk powders using near-infrared hyperspectral imaging and band ratio

    Science.gov (United States)

    Since 2008, the detection of the adulterant melamine (2,4,6-triamino-1,3,5-triazine) in food products has become the subject of research due to several food safety scares. Near-infrared (NIR) hyperspectral imaging offers great potential for food safety and quality research because it combines the fe...

  6. Visible light induced photobleaching of methylene blue over melamine-doped TiO2 nanocatalyst

    Science.gov (United States)

    TiO2 doping with N-rich melamine produced a stable, active and visible light sentisized nanocatalyst that showed a remarkable efficiency towards the photobleaching of a model compound – methylene blue (MB) in aqueous solution. The photobleaching followed a mixed reaction order ki...

  7. A chiral pinwheel supramolecular network driven by the assembly of PTCDI and melamine

    NARCIS (Netherlands)

    Silly, Fabien; Shaw, Adam Q.; Castell, Martin R.; Briggs, G. A. D.

    2008-01-01

    The mixing of perylene-3,4,9,10-tetracarboxylic diimide ( PTCDI) and 1,3,5-triazine-2,4,6-triamine ( melamine) at room temperature in a ratio of 3 : 4 on Au( 111) leads to the formation of a new chiral " pinwheel'' structure.

  8. Pairs and heptamers of C(70) molecules ordered via PTCDI-melamine supramolecular networks

    NARCIS (Netherlands)

    Silly, Fabien; Shaw, Adam Q.; Porfyrakis, Kyriakos; Briggs, G. A. D.; Castell, Martin R.

    2007-01-01

    In this paper, we report on the use of two PTCDI-melamine supramolecular networks on Au(111) to trap C(70) molecules. The different supramolecular networks were formed by changing the postannealing temperature after molecular deposition. We observed, using scanning tunneling microscopy, that the

  9. Cyanuric acid and melamine on Au(111): Structure and energetics of hydrogen-bonded networks

    NARCIS (Netherlands)

    Xu, H.; Xu, Wei; Dong, Mingdong; Gersen, H.; Rauls, Eva; Vazquez Campos, M.S.; Vazquez-Campos, Socorro; Crego Calama, Mercedes; Reinhoudt, David; Stensgaard, Ivan; Laegsgaard, Erik; Linderoth, Trolle R.; Besenbacher, Flemming

    2007-01-01

    Expect the unexpected: The interaction between cyanuric acid (CA) and melamine (M) molecules is a key structural motif in supramolecular chemistry. The adsorption and coadsorption of M and CA on a Au(111) surface under ultrahigh vacuum (UHV) is investigated using STM with submolecular resolution. In

  10. Synthesis, Structure and Properties of Melamine-Based pTHF-Urethane Supramolecular Compounds

    NARCIS (Netherlands)

    Öjelund, Karin; Loontjens, Ton; Steeman, Paul; Palmans, Anja; Maurer, Frans

    2003-01-01

    The properties of melamine based supramolecular compounds have been studied with rheological, thermal, mechanical, dielectric and scattering techniques and compared with similar covalently bonded materials. The complexes are based on a linear pTHF-diol (M¯n=1 000) connected via a diisocyanate with

  11. Temperature dependent Raman spectroscopy of melamine and structural analogs in milk powder

    Science.gov (United States)

    Hyperspectral Raman imaging has the potential for rapid screening of solid-phase samples for potential adulterants. We found that the Raman spectra of melamine analogs changed dramatically and uniquely as a function of elevated temperature. Raman spectra were acquired for urea, biuret, cyanuric acid...

  12. Hydrogen-bonding patterns in 5-fluorocytosine–melamine co-crystal (4/1

    Directory of Open Access Journals (Sweden)

    Marimuthu Mohana

    2016-04-01

    Full Text Available The asymmetric unit of the title compound, 4C4H4FN3O·C3H6N6, comprises of two independent 5-fluorocytosine (5FC molecules (A and B and one half-molecule of melamine (M. The other half of the melamine molecule is generated by a twofold axis. 5FC molecules A and B are linked through two different homosynthons [R22(8 ring motif]; one is formed via a pair of N—H...O hydrogen bonds and the second via a pair of N—H...N hydrogen bonds. In addition to this pairing, the O atoms of 5FC molecules A and B interact with the N2 amino group on both sides of the melamine molecule, forming a DDAA array of quadruple hydrogen bonds and generating a supramolecular pattern. The 5FC (molecules A and B and two melamine molecules interact via N—H...O, N—H...N and N—H...O, N—H...N, C—H...F hydrogen bonds forming R66(24 and R44(15 ring motifs. The crystal structure is further strengthened by C—H...F, C—F...π and π–π stacking interactions.

  13. Melamine functionalized silver nanoparticles as the probe for electrochemical sensing of clenbuterol.

    Science.gov (United States)

    Miao, Peng; Han, Kun; Sun, Haixuan; Yin, Jian; Zhao, Jing; Wang, Bidou; Tang, Yuguo

    2014-06-11

    Clenbuterol, a member of β-agonist family, has now been a serious threat to human health due to its illegal usage in the livestock feeding. Herein, we describe the application of melamine functionalized silver nanoparticles (M-AgNPs) as the electrochemical probe for simple, fast, highly sensitive and selective detection of clenbuterol. Generally, AgNPs are prepared and functionalized by melamine. After interacting with melamine modified gold electrode in the presence of clenbuterol, M-AgNPs can be immobilized on the surface of the electrode via the hydrogen-bonding interactions between clenbuterol and melamine. This sandwich structure permits sensitive and selective detection of clenbuterol. Since M-AgNPs can provide a couple of well-defined sharp silver stripping peaks, which stands for a highly characteristic solid-state Ag/AgCl reaction, a rather low detection limit of 10 pM can be achieved. The detection range is from 10 pM to 100 nM, which is quite wide. This developed biosensor can potentially be used for clenbuterol detection in biological fluids in the presence of various interferences.

  14. Determination of melamine of milk based on two-dimensional correlation infrared spectroscopy

    Science.gov (United States)

    Yang, Ren-jie; Liu, Rong; Xu, Kexin

    2012-03-01

    The adulteration of milk with harmful substances is a threat to public health and beyond question a serious crime. In order to develop a rapid, cost-effective, high-throughput analysis method for detecting of adulterants in milk, the discriminative analysis of melamine is established in milk based on the two-dimensional (2D) correlation infrared spectroscopy in present paper. Pure milk samples and adulterated milk samples with different content of melamine were prepared. Then the Fourier Transform Infrared spectra of all samples were measured at room temperature. The characteristics of pure milk and adulterated milk were studied by one-dimensional spectra. The 2D NIR and 2D IR correlation spectroscopy were calculated under the perturbation of adulteration concentration. In the range from 1400 to 1800 cm-1, two strong autopeaks were aroused by melamine in milk at 1464 cm-1 and 1560 cm-1 in synchronous spectrum. At the same time, the 1560 cm-1 band does not share cross peak with the 1464 cm-1 band, which further confirm that the two bands have the same origin. Also in the range from 4200 to 4800 cm-1, the autopeak was shown at 4648 cm-1 in synchronous spectrum of melamine in milk. 2D NIR-IR hetero-spectral correlation analysis confirmed that the bands at 1464, 1560 and 4648 cm-1 had the same origin. The results demonstrated that the adulterant can be discriminated correctly by 2D correlation infrared spectroscopy.

  15. Simple spectrophotometric method for determination of melamine in liquid milks based on green Mannich reaction

    Science.gov (United States)

    Chansuvarn, Woravith; Panich, Sirirat; Imyim, Apichat

    2013-09-01

    A new and simple spectrophotometric method has been developed and validated for measuring the contamination of melamine in different milk products. The method is based upon measuring the absorption of the complex formed from melamine, 4-hydroxyacetophenone (Hap) and 1-pyrene carboxaldehyde (Pcd), which was adapted from the Mannich reaction. Quantitative analysis was done at a wavelength of 236 nm within a few minutes. The reaction was optimized by focusing on both obtaining high performance of the method and to concern the volatility and toxicity of used reagents. This method provided a linear dynamic range, limit of detection and limit of quantification of 0.100-3.78, 0.08 and 0.14 mg L-1, respectively. The relative standard deviation (RSD) was 3.6% (n = 10). The recoveries of melamine spiked liquid milk samples, with melamine concentrations of 0.63, 1.26, 1.89 and 2.52 mg L-1, were 87.7 ± 3.7%, 91.1 ± 8.8%, 89.2 ± 4.4% and 90.6 ± 3.6% (n = 3), respectively.

  16. Determinants of cyanuric acid and melamine assembly in water.

    Science.gov (United States)

    Ma, Mingming; Bong, Dennis

    2011-07-19

    While the recognition of cyanuric acid (CA) by melamine (M) and their derivatives has been known to occur in both water and organic solvents for some time, analysis of CA/M assembly in water has not been reported (Ranganathan, A.; Pedireddi, V. R.; Rao, C. N. R. J. Am. Chem. Soc.1999, 121, 1752-1753; Mathias, J. P.; Simanek, E. E.; Seto, C. T.; Whitesides, G. M. Macromol. Symp.1994, 77, 157-166; Zerkowski, J. A.; MacDonald, J. C.; Seto, C. T.; Wierda, D. A.; Whitesides, G. M. J. Am. Chem. Soc.1994, 116, 2382-2391; Mathias, J. P.; Seto, C. T.; Whitesides, G. M. Polym. Prepr.1993, 34, 92-93; Seto, C. T.; Whitesides, G. M. J. Am. Chem. Soc.1993, 115, 905-916; Zerkowski, J. A.; Seto, C. T.; Whitesides, G. M. J. Am. Chem. Soc.1992, 114, 5473-5475; Seto, C. T.; Whitesides, G. M. J. Am. Chem. Soc.1990, 112, 6409-6411; Wang, Y.; Wei, B.; Wang, Q. J. Chem. Cryst.1990, 20, 79-84; ten Cate, M. G. J.; Huskens, J.; Crego-Calama, M.; Reinhoudt, D. N. Chem.-Eur. J.2004, 10, 3632-3639). We have examined assembly of CA/M, as well as assembly of soluble trivalent CA and M derivatives (TCA/TM), in aqueous solvent, using a combination of solution phase NMR, isothermal titration and differential scanning calorimetry (ITC/DSC), cryo-transmission electron microscopy (cryo-TEM), and synthetic chemistry. While the parent heterocycles coprecipitate in water, the trivalent system displays more controlled and cooperative assembly that occurs at lower concentrations than the parent and yields a stable nanoparticle suspension. The assembly of both parent and trivalent systems is rigorously 1:1 and proceeds as an exothermic, proton-transfer coupled process in neutral pH water. Though CA and M are considered canonical hydrogen-bonding motifs in organic solvents, we find that their assembly in water is driven in large part by enthalpically favorable surface-area burial, similar to what is observed with nucleic acid recognition. There are currently few synthetic systems capable of robust molecular

  17. Surface-enhanced Raman detection of melamine on silver-nanoparticle-decorated silver/carbon nanospheres: effect of metal ions.

    Science.gov (United States)

    Chen, Li-Miao; Liu, You-Nian

    2011-08-01

    Silver/carbon (Ag/C) core-shell nanospheres synthesized by a hydrothermal method were used as templates for fabricating silver nanoparticle-decorated Ag/C (Ag/C/AgNps) nanospheres. The particle size of Ag nanoparticles can be tuned by varying the concentration of Ag precursor. Detection of melamine molecules at concentrations as low as 5.0×10(-8) M shows that the Ag/C/AgNps nanosphere is a good SERS-active substrate. The effect of heavy metal ions on the detection of melamine is also investigated. It was found that the SERS spectrum profile of melamine is very sensitive to the presence of heavy metal ions: the peak positions of the SERS bands exhibit some apparent change with the kind of metal ion, showing a blue or red shift compared with those in the SERS spectrum of melamine; the SERS signal intensity decrease with increasing the concentration of metal ion.

  18. A nitrogen-doped graphene film prepared by chemical vapor deposition of a methanol mist containing methylated melamine resin

    Science.gov (United States)

    Mizuno, T.; Takizawa, M.; Tsuchiya, B.; Jinno, M.; Bandow, S.

    2013-11-01

    The effect of nitrogen doping on the sheet resistivity of a graphene film is systematically studied by changing the doping concentration. The nitrogen-doped graphene film is grown on a Cu foil by chemical vapor deposition using an ultrasonically generated methanol mist containing methylated melamine resin (simply called ‘melamine’). Using this method, it is found that the magnitude of the sheet resistivity is controllable by changing the melamine concentration. Increasing the melamine concentration up to ˜0.03 % causes a decrease of the sheet resistivity. We explain this by the substitutional doping of nitrogen atoms. A further increase in melamine concentration causes an increase of the sheet resistivity. This increase may be caused by the formation of pyridinic or pyrrolic N instead of substitutional N. Electron energy loss spectroscopy analyses for the carbon K-edge indicate a decrease of π ∗ character with increasing melamine concentration up to 0.08 % and then it recovers for higher concentration. This is due to a separation of the graphitic region and the defective region at high melamine concentration.

  19. A network signal amplification strategy of ultrasensitive photoelectrochemical immunosensing carcinoembryonic antigen based on CdSe/melamine network as label.

    Science.gov (United States)

    Li, Jiaojiao; Zhang, Yong; Kuang, Xuan; Wang, Zhiling; Wei, Qin

    2016-11-15

    Taking advantage of CdSe/melamine network as label and Au-TiO2 as substrate, this work developed a novel kind of signal amplification strategy for fabricating photoelectrochemical (PEC) immunoassay. The melamine, a star-shaped triamino molecule, was firstly used for readily capturing CdSe QDs and forming a CdSe/melamine network, which was formed through strong interactions between the carboxyl groups of TGA-stabilized CdSe QDs and the three amino groups of each melamine molecule. In this strategy, the primary antibody (Ab1) was immobilized onto Au-TiO2 substrate, which made the photoelectric conversion efficiency increase significantly. After the formed Ab2-CdSe/melamine network labels were captured onto the electrode surface via the specific antibody-antigen interaction, the photoelectric activity could be further enhanced via the interaction between the Au-TiO2 substrate and CdSe/melamine network. Due to this amplification of PEC signals and the special structure of the label, the fabricated PEC immunosensor was applied for sensitive and specific detection of cancer biomarker carcinoembryonic antigen (CEA), and displayed a wide linear range (0.005-1000ngmL(-1)) and low detection limit (5pgmL(-1)). In addition, the immunosensor was performed with good stability and reproducibility, and the results to analyze human serum samples were satisfactory. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Biosynthesis and computational analysis of amine-ended dual thiol ligand functionalized gold nanoparticles for conventional spectroscopy detection of melamine.

    Science.gov (United States)

    Anand, K; Singh, Thishana; Madhumitha, G; Phulukdaree, A; Gengan, Robert M; Chuturgoon, A A

    2017-04-01

    The bio-synthesized DTAuNPs have an average size of 21nm. The aggregation extent depends on the concentration of melamine, which was validated by UV-vis spectra and visual method of melamine detection was developed. The major observation in this method was the color change of DTAuNPs from red to purple due to the aggregation of ligand capped gold nanoparticles instigated by melamine. The reaction of color changes were processed due to the shifting of bonding in hydrogen in between nanoparticles and melamine. The aggregation extent depends on the concentration of melamine, which can be validated UV-vis spectra and visual method of detecting melamine is developed. The electron density and conventional UV-vis, FTIR spectroscopy and DFT studies on the ligand was performed using computational methods. The theoretical and experimental data for the energy transitions and the molar extinction coefficients of the ligands studied has been obtained. Further, the ligand capped gold nanoparticles was assessed for cytotoxicity against A549 cells which resulted in significant decrease in cell viability was noted in 50μg/mL DTAu, 4-ATP and AXT treated cells at 2h (85% and 66%) and 6h (83% and 36%) respectively, (p<0.01) were studied and reported in this manuscript. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. A sensitive spectrofluorimetric method for the quantification of melamine residue in milk powder using the Mannich reaction in aqueous solutions.

    Science.gov (United States)

    Rima, Jamil; Assaker, Karine; El Omar, Fawaz; karim, Chawki bou

    2013-11-15

    The objective of this study was to develop a spectrofluorimetric method for the quantitative determination of melamine. The method was based on the complexation of melamine with a mixture of formaldehyde and chemicals including a ketone group, as described by the Mannich reaction. The complex was determined by spectrofluorimetric measurement as it is characterized by specific spectroscopic properties that are related to the chromophore of the ketone compounds. 1,3-Diphenylpropane-1,3-dione (DPPD) was tested as a ketone compound. The fluorescence spectrum of the complex presented a maximum of absorption at 325 nm.A quenching of the fluorescence occurred when melamine was added into the solution. The kinetic of fluorescence quenching was followed to determine quantitatively the melamine concentration. An internal standard was added to quantify melamine. The method was tested to determine the level of melamine in contaminated milk powder. The recovery value was 97% and the limit of detection was 0.007 μg mL(-1.) © 2013 Elsevier B.V. All rights reserved.

  2. Development of Self Fire Retardant Melamine-Animal Glue Formaldehyde (MGF) Resin for the Manufacture of BWR Ply Board

    Science.gov (United States)

    Khatua, Pijus Kanti; Dubey, Rajib Kumar; Roymahapatra, Gourisankar; Mishra, Anjan; Shahoo, Shadhu Charan; Kalawate, Aparna

    2017-10-01

    Wood is one of the most sustainable, naturally growing materials that consist mainly of combustible organic carbon compounds. Since plywood are widely used nowadays especially in buildings, furniture and cabinets. Too often the fire behavior of ply-board may be viewed as a drawback. Amino-plastic based thermosetting resin adhesives are the important and most widely used in the plywood panel industries. The fire retardant property of wood panel products by adding animal glue as an additive in the form of MGF resin and used as substitute of melamine for manufacture of plywood. Environment concerns and higher cost of petroleum based resins have resulted in the development of technologies to replace melamine partially by biomaterials for the manufacturing of resin adhesive. Natural bio-based materials such as tannin, CNSL (cardanol), lignin, soya etc. are used as partial substitution of melamine. This article presents the development of melamine-animal glue formaldehyde resin as plywood binder. About 30 % melamine was substituted by animal glue and optimized. The different physico-mechanical and fire retardant property properties tested as per IS: 1734-1983 and IS: 5509-2000 respectively are quite satisfactory. The production of adhesive from melamine with compatible natural proteinous material is cost effective, eco-friendly and enhance the fire retardant property.

  3. [Determination of melamine and ammeline in eggs and meat using hydrophilic interaction liquid chromatography].

    Science.gov (United States)

    Li, Yanzhao; Hao, Weiqiang; Wang, Yubo; Chen, Qiang; Li, Jinchun; Sun, Xiaoli

    2012-07-01

    A hydrophilic interaction liquid chromatographic (HILIC) method for the determination of melamine and its degradation product ammeline in eggs and meat has been developed. The separation was carried out on a ZIC-HILIC column with 3 mmol/L NH4H2PO4 (pH 6.9)-acetonitrile (20: 80, v/v) as mobile phase at the flow rate of 0.8 mL/min, and detected at 220 nm. Compared with the reversed-phase liquid chromatography, this method can avoid the use of ion pair reagents and thus simplify the composition of mobile phase. Under the above chromatographic conditions, melamine and ammeline had good peak shapes and moderate retention times. Good separation between these compounds and the substances that were naturally contained in the samples can be achieved. For the sample preparation, the analytes were first extracted with 0.1% phosphoric acid due to the basicity of melamine and ammeline. Then, metaphosphoric acid and acetonitrile were used to remove proteins and saccharides by precipitation. After the filtration and removal of acetonitrile by rotary evaporation under vacuum, the filtrate was cleaned-up by solid-phase extraction (SPE) technique in which a cation exchange column was used. The SPE column was activated by using methanol and 0.1% phosphoric acid. A solution of 5% ammonia methanol was chosen as eluent. The residues obtained from the eluant by evaporating the solvent were resolved in the mobile phase. It was found that there was a good linear relationship between concentration and detector response within the range of 0.4-40 mg/L. The limits of detection were 2 mg/kg for both melamine and ammeline. The average recoveries were between 80% and 105% in the spiked range of 2-10 mg/kg. The relative standard deviations were not more than 10%. The solutions of melamine and ammeline were stable in a month. The established method can be used in practice to determine melamine and ammeline simultaneously in egg and meat samples.

  4. The effect of α-cellulose fiber on the properties of melamine-formaldehyde molding compounds

    International Nuclear Information System (INIS)

    Khatibi, M. A.; Beheshti, M. A.; Morshedian, J.

    2001-01-01

    Melamine-formaldehyde molding compounds have found different industrial applications. This is due to their good mechanical properties such as hardness, gloss and high modulus and strength. One of the major components of these compounds is α-cellulose fiber and has a major effect on the mechanical properties. Although this fiber is being used in these compounds for a long time, there is not much data available of α-cellulose fibers on the physical and mechanical properties of melamine-formaldehyde molding compounds being investigated. Results show that although the microstructures of these two fibers are quite different from each other, but they do not have any effect on the mechanical properties of the molding. Whereas, it has a significant effect on the wettability (processing condition) and glossiness of the mol dings. Since this latter property is very important in house wares applications, the darker mol dings can not be used in domestic applications

  5. Efficient adsorption of Hg (II) ions in water by activated carbon modified with melamine

    Science.gov (United States)

    Qin, Hangdao; Meng, Jingling; Chen, Jing

    2018-04-01

    Removal of Hg (II) ions from industrial wastewater is important for the water treatment, and adsorption is an efficient treatment process. Activated carbon (AC) was modified with melamine, which introduced nitrogen-containing functional groups onto AC surface. Original AC and melamine modified activated carbon (ACM) were characterized by elemental analysis, N2 adsorption-desorption, determination of the pH of the point of zero charge (pHpzc) and X-ray photoelectron spectroscopy (XPS) and their performance in the adsorption of Hg(II) ions was investigated. Langmuir model fitted the experimental data of equilibrium isotherms well. ACM showed the higher Hg (II) ions adsorption capacity, increasing more than more than 1.8 times compared to the original one. Moreover, ACM showed a wider pH range for the maximum adsorption than the parent AC.

  6. Simultaneous determination of urea and melamine in milk powder by nonlinear chemical fingerprint technique.

    Science.gov (United States)

    Ma, Yongjie; Dong, Wenbin; Bao, Hongliang; Fang, Yue; Fan, Cheng

    2017-04-15

    This paper proposed a nonlinear chemical fingerprint method for simultaneous determination of urea and melamine in milk powder using "H + +Ce 4+ +BrO 3 - +malonic acid" as reaction system. A multiple linear relationship was obtained between the adulterants content in milk powder and inductive time of corresponding mixed milk powder. System analysis model established with classical least squares (CLS) method was then used to calculate the content of urea and melamine in milk powder. The method was successfully applied to milk powder samples and had good recoveries in the range of 99.17-100.25%, with the relative standard deviation (RSD) in the range of 0.60-4.12%. The limits of detection for urea and melamine were 0.33μg·g -1 and 0.05μg·g -1 , respectively. The limits of quantification were 1.11μg·g -1 and 0.18μg·g -1 , respectively. The results indicated that the new method was feasible and had the advantages of low cost, simple operation and without pretreatment of samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Synthesis of graphitic carbon nitride by reaction of melamine and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Dante, Roberto C., E-mail: rcdante@yahoo.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martin-Ramos, Pablo, E-mail: pablomartinramos@gmail.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Correa-Guimaraes, Adriana, E-mail: acg@iaf.uva.es [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martin-Gil, Jesus, E-mail: jesusmartingil@gmail.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain)

    2011-11-01

    Highlights: {yields} Graphitic carbon nitrides by CVD of melamine and uric acid on alumina. {yields} The building blocks of carbon nitrides are heptazine nuclei. {yields} Composite particles with alumina core and carbon nitride coating. - Abstract: Graphitic carbon nitrides were synthesized starting from melamine and uric acid. Uric acid was chosen because it thermally decomposes, and reacts with melamine by condensation at temperatures in the range of 400-600 deg. C. The reagents were mixed with alumina and subsequently the samples were treated in an oven under nitrogen flux. Alumina favored the deposition of the graphitic carbon nitrides layers on the exposed surface. This method can be assimilated to an in situ chemical vapor deposition (CVD). Infrared (IR) spectra, as well as X-ray diffraction (XRD) patterns, are in accordance with the formation of a graphitic carbon nitride with a structure based on heptazine blocks. These carbon nitrides exhibit poor crystallinity and a nanometric texture, as shown by transmission electron microscopy (TEM) analysis. The thermal degradation of the graphitic carbon nitride occurs through cyano group formation, and involves the bridging tertiary nitrogen and the bonded carbon, which belongs to the heptazine ring, causing the ring opening and the consequent network destruction as inferred by connecting the IR and X-ray photoelectron spectroscopy (XPS) results. This seems to be an easy and promising route to synthesize graphitic carbon nitrides. Our final material is a composite made of an alumina core covered by carbon nitride layers.

  8. Broccoli-like porous carbon nitride from ZIF-8 and melamine for high performance supercapacitors

    Science.gov (United States)

    Cai, Chenglong; Zou, Yongjin; Xiang, Cuili; Chu, Hailiang; Qiu, Shujun; Sui, Qingli; Xu, Fen; Sun, Lixian; Shah, Afzal

    2018-05-01

    Broccoli-like porous carbon nitride is synthesized by simple one-step carbonization of a composite comprising a Zn-based zeolitic imidazolate framework (ZIF-8) and melamine. The introduction of melamine into the ZIF-8 framework not only increases the N content of the composite and the surface area of the carbonization product, but also induces the formation of a flower-like structure. The carbon obtained from the ZIF-8/melamine composite by the proposed carbonization process at a temperature of 800 °C (ZM-C-800) is found to have a unique three-dimensional broccoli-like shape, a nanoscale size, and an extremely high doping N content (28.3 at.%). These properties substantially improve the electrochemical performance of ZM-C-800, as represented by a high specific capacitance of 359.1 F g-1 at a current density of 1 A g-1, much higher than that of ZIF-8. Furthermore, a symmetric supercapacitor fabricated with two ZM-C-800 electrodes exhibits a power density of 498.5 W kg-1 for an energy density of 11.4 Wh kg-1. This indicates the strong potential of ZM-C-800 for use in the fabrication of energy storage devices.

  9. Colorimetric detection of melamine in milk based on Triton X-100 modified gold nanoparticles and its paper-based application

    Science.gov (United States)

    Gao, Nan; Huang, Pengcheng; Wu, Fangying

    2018-03-01

    In this study, we have developed a method for rapid, highly efficient and selective detection of melamine. The negatively charged citrate ions form an electrostatic layer on gold nanoparticles (AuNPs) and keep the NPs dispersed and stable. When citrate-capped AuNPs were further modified with Triton X-100, it stabilized the AuNPs against the conditions of high ionic strength and a broad pH range. However, the addition of melamine caused the destabilization and aggregation of NPs. This may be attributed to the interaction between melamine and the AuNPs through the ligand exchange with citrate ions on the surface of AuNPs leading Triton X-100 to be removed. As a result, the AuNPs were unstable, resulting in the aggregation. The aggregation induced a wine red-to-blue color change, and a new absorption peak around 630 nm appeared. Triton X-100-AuNPs could selectively detect melamine at the concentration as low as 5.1 nM. This probe was successfully applied to detect melamine in milk. Furthermore, paper-based quantitative detection system using this colorimetric probe was also demonstrated by integrating with a smartphone.

  10. Silylated melamine and cyanuric acid as precursors for imprinted and hybrid silica materials with molecular recognition properties.

    Science.gov (United States)

    Arrachart, Guilhem; Carcel, Carole; Trens, Philippe; Moreau, Jöel J E; Wong Chi Man, Michel

    2009-06-15

    Two monotrialkoxysilylated compounds that consist of complementary fragments of melamine (M) and cyanuric acid (CA) have been synthesised. The molecular recognition properties of the M and CA fragments through complementary hydrogen bonds (DAD and ADA; D=donor, A=acceptor) are the key factor used to direct the formation of hybrid silica materials by using a sol-gel process. These materials were synthesised following two methods: First, an organo-bridged silsesquioxane was obtained by the hydrolysis of the two complementary monotrialkoxysilylated melamine and cyanuric acid derivatives, with fluoride ions as a catalyst. The hydrogen-bonding interactions between the two organic fragments are responsible for the formation of the bridging unit. The transcription of the assembly into the hybrid material was characterised and evidenced by solid-state NMR (29Si, 13C) and FTIR spectroscopic experiments. Second, the molecular recognition was exploited to synthesise an imprinted hybrid silica. This material was prepared by co-condensation of tetraethyl orthosilicate (TEOS) with the monosilylated cyanuric acid derivative (CA) templated by nonsilylated melamine. The melamine template was completely removed by treating the solid material with hydrochloric acid. The reintroduction of the template was performed by treating the resulting material with an aqueous suspension of melamine. These steps were monitored and analysed by several techniques, such as solid-state NMR (29Si, 13C) and FTIR spectroscopic analysis and nitrogen adsorption-desorption isotherms.

  11. Selective optosensing of clenbuterol and melamine using molecularly imprinted polymer-capped CdTe quantum dots.

    Science.gov (United States)

    The Huy, Bui; Seo, Min-Ho; Zhang, Xinfeng; Lee, Yong-Ill

    2014-07-15

    A novel procedure for the optosensing of clenbuterol and melamine was developed using molecularly imprinted polymer-capped CdTe quantum dots (MIP-CdTe QDs). The MIP-CdTe QDs were synthesized by a radical polymerization process among CdTe QDs, a template, 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS). The sizes of the MIP-CdTe particles were controlled by the speed of polymerization, concentration of the template, concentration of the quantum dots, and the ratio of template, monomer and cross-linker. Excellent selectivity and high sensitivity of MIP-CdTe QDs toward clenbuterol/melamine molecules were observed based on the fluorescence quenching of QDs. Experimental results showed that the optimum molar ratios of template, monomer, and cross-linker were 1:8:20 and 1:4:20 for analyzing clenbuterol and melamine, respectively. Under optimum conditions, these MIP-CdTe QDs showed a limit of detection of 0.4 μM (120 ng/mL) for clenbuterol and 0.6 μM (75 ng/mL) for melamine. The feasibility of the developed method in real samples was successfully evaluated through the analysis of clenbuterol and melamine in milk and liver samples with satisfactory recoveries of 92-97%. The MIP-CdTe QDs could be easily regenerated for subsequent sample analysis with water. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Hydrogen-bonding recognition-induced aggregation of gold nanoparticles for the determination of the migration of melamine monomers using dynamic light scattering.

    Science.gov (United States)

    Wu, Long; Chen, Kun; Lu, Zhicheng; Li, Tingting; Shao, Kang; Shao, Feng; Han, Heyou

    2014-10-03

    The migration of melamine monomers from food contact materials has aroused particular attention since the 2008 melamine-tainted milk scandal in China. However, the determination of melamine monomer's migratory quantity (MMMQ) has remained an open question because of the complex sample pretreatment and the low sensitivity. Based on the hydrogen bonding interaction between DNA thymine and melamine, this paper described a simple and rapid method focusing on the measurement of MMMQ from melamine tableware by gold nanoparticles (GNPs) and dynamic light scattering (DLS). With the presence of probe DNA (p-DNA), the GNPs were stable in NaCl solution (0.06 M), whereas they became aggregated when the p-DNA hybridized with melamine. The change in the hydrodynamic diameter of GNPs could be detected by DLS technology. Under the optimal conditions, the average diameter increased linearly with the concentration of melamine over the range from 5.0 to 320.0 μg L(-1), and showed a detection limit of 2.0 μg L(-1) (3σ/slope). The MMMQ was investigated within a range from 6.00×10(-4) to 2.58×10(-1) mg dm(-2) (n≥3) in four different food simulants at different temperatures and time points. The results suggest that the DLS method has great potential in the analysis of the migration of melamine monomers. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Single-run separation of closely related cationic and anionic compounds by CE-ESI-MS : application to the simultaneous analysis of melamine and its analogs in milk

    NARCIS (Netherlands)

    Kohler, I.; Cognard, E.; Marchi, I.; Ortelli, D.; Edder, P.; Veuthey, J.; Rudaz, S.; Schappler, J.

    2011-01-01

    In recent years, two adulteration incidents concerning the addition of melamine, a nitrogen-rich industrial small polar compound, to pet food and infant formula products have occurred in China. These issues prompted laboratories to develop methods for the analysis of melamine and related compounds

  14. Integrated photografted molecularly imprinted polymers with a cellulose acetate membrane for the extraction of melamine from dry milk before HPLC analysis.

    Science.gov (United States)

    Akbari-Adergani, Behrouz; Sadeghian, Gholam-Hossein; Alimohammadi, Alireza; Esfandiari, Zahra

    2017-03-01

    In this study, a new separation technique based on membrane extraction is described for the determination of melamine in dry milk. The water-compatible cellulose acetate membrane, which is photografted by melamine imprinted nanospheres, was prepared by placing the membrane into the polymerization solution containing methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as cross-linker, acetonitrile as porogen, and melamine as the template molecule. The characterization of the polymeric membrane was performed by Fourier transmission infrared spectroscopy and scanning electron microscopy. This integrated composite membrane was used as a solid-phase extraction medium for the extraction of melamine from dry milk samples. Various parameters affecting the extraction efficiency of the membrane were evaluated. The results showed higher binding capacity for melamine imprinted membranes in comparison with the nonimprinted membranes. High-performance liquid chromatography analysis showed that the extraction of melamine from dry milk by the photografted cellulose acetate membrane had a linear calibration curve in the range of 0.02-11.80 μg/mL with an excellent precision of 2.73%. The limit of detection and quantification of melamine was 0.007 and 0.020 μg/mL, respectively. The recoveries of melamine were in the range of 88.7-94.8%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. FTIR analysis and the effects of alkyd/melamine resin ratio on the properties of the coatings

    Directory of Open Access Journals (Sweden)

    Cakić Suzana M.

    2009-01-01

    Full Text Available Alkyd/melamine resin mixtures are mainly used in industrial baking enamels. The effects of the alkyd/butylated melamine resin ratio (from 90/10 to 50/50 and curing temperature (from 110 to 180°C on the crosslinking and properties of the coating are presented in this paper. The curing reactions through functional groups of resins were monitored by FT-IR spectroscopy. The hardness, elasticity, degree of adherence and gloss were also determined. Optimal coating properties could be achieved with an alkyd/melamine resin ratio of 80/20, a curing temperature of 150°C and a curing time of 20 min.

  16. The effects of alkyd/melamine resin ratio and curing temperature on the properties of the coatings

    Directory of Open Access Journals (Sweden)

    RADMILA Z. RADICEVIC

    2005-04-01

    Full Text Available Synthetic resins are used as binders in protective coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of a coating called “baking enamel” cured through functional groups of resins. The effects of the alkyd/butylated melamine resin ratio (from 85/15 to 70/30 and curing temperature (from 100°C to 160°C on the crosslinking and properties of the coating are presented in this paper. The degree of curing was determined by differential scanning calorimetry. These data were used for the estimation of the degree of crosslinking. The hardness, elasticity, impact resistance, degree of adherence and gloss were also determined. Optimal coating properties could be achieved with an alkyd/melamine resin ratio of 75/25, a curing temperature of 130 °C and a curing time of 30 min.

  17. FTIR analysis and the effects of alkyd/melamine resin ratio on the properties of the coatings

    OpenAIRE

    Cakić Suzana M.; Bošković Ljiljana B.

    2009-01-01

    Alkyd/melamine resin mixtures are mainly used in industrial baking enamels. The effects of the alkyd/butylated melamine resin ratio (from 90/10 to 50/50) and curing temperature (from 110 to 180°C) on the crosslinking and properties of the coating are presented in this paper. The curing reactions through functional groups of resins were monitored by FT-IR spectroscopy. The hardness, elasticity, degree of adherence and gloss were also determined. Optimal coating properties could be achieved wit...

  18. Activation analysis of indium, KCl, and melamine by using a laser-induced neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungman; Lee, Kitae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cha, Hyungki [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2014-04-15

    A laser-induced repetitively operated fast neutron source with a neutron yield of 4 x 10{sup 5} n/pulse and a pulse repetition rate of 5 Hz, which was developed using a deuterated polystyrene film target and a 24-TW femtosecond laser, was applied for laser activation analyses of indium, KCl, and melamine samples. The nuclear reactions of the measured gamma spectra for the activated samples were identified as (n, γ), (n, n'), and (n, 2n) reactions. These indicate possible usage of the neutron source for practical activation analyses of various materials.

  19. Melamine modified P25 with heating method and enhanced the photocatalytic activity on degradation of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huiqin [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Jinze; Ma, Changchang [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China); Lu, Ziyang [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Huo, Pengwei, E-mail: huopw1@163.com [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan, Yongsheng [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-02-28

    Highlights: • We demonstrated the as-prepared photocatalyst of g-C{sub 3}N{sub 4}-TiO{sub 2} with the commercial TiO{sub 2} (P25) composited melamine under ball milling and calcined. • The enhanced photocatalytic performance could be mainly attributed to the suitable band gap structure with heterojunction of CN-P25. • The possible photocatalytic mechanism of g-C{sub 3}N{sub 4}/P25 under visible light irradiation is proposed. - Abstract: The graphitic carbon nitride (g-C{sub 3}N{sub 4}), as one photocatalyst which possess the suitable band gap, is better for modified TiO{sub 2} and enhanced photocatalytic degradation of organic pollutants. In this work, the g-C{sub 3}N{sub 4}/TiO{sub 2} were successfully prepared via directly calcined the mixture of melamine and P25. The as-prepared g-C{sub 3}N{sub 4}/TiO{sub 2} photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and high resolution electron microscopy (HRTEM), Raman and Fourier transform-infrared spectroscopy (FT-IR). The photocatalytic performances of g-C{sub 3}N{sub 4}/TiO{sub 2} composites were investigated by degradation of ciprofloxacin. The results showed that the g-C{sub 3}N{sub 4} and P25 were successfully composited, and the bond of C–N was well formed, the calcined temperature for as-prepared photocatalysts and the ratio of melamine and P25 were important to the degradation rate of ciprofloxacin. When the mixture of melamine and P25 with 1:2, and calcined temperature at 600 °C, the degradation rate of ciprofloxacin could reach 95% in 60 min. The enhanced photocatalytic performances could be mainly attributed to the suitable band gap structure with heterojunction of CN-P25. Finally, the possible transferred processes of photoelectrons and photoholes were proposed.

  20. Evaluation of Colloids and Activation Agents for Determination of Melamine Using UV-SERS

    OpenAIRE

    Kämmer, Evelyn; Dörfer, Thomas; Csáki, Andrea; Schumacher, Wilm; Da Costa Filho, Paulo Augusto; Tarcea, Nicolae; Fritzsche, Wolfgang; Rösch, Petra; Schmitt, Michael; Popp, Jürgen

    2012-01-01

    UV-SERS measurements offer a great potential for environmental or food (detection of food contaminats) analytics. Here, the UV-SERS enhancement potential of various kinds of metal colloids, such as Pd, Pt, Au, Ag, Au–Ag core–shell, and Ag–Au core–shell with different shapes and sizes, were studied using melamine as a test molecule. The influence of different activation (KF, KCl, KBr, K2SO4) agents onto the SERS activity of the nanomaterials was investigated, showing that the combination of a ...

  1. Melamine-containing polyphosphazene wrapped ammonium polyphosphate: A novel multifunctional organic-inorganic hybrid flame retardant.

    Science.gov (United States)

    Qiu, Shuilai; Ma, Chao; Wang, Xin; Zhou, Xia; Feng, Xiaming; Yuen, Richard K K; Hu, Yuan

    2018-02-15

    To achieve superior fire safety epoxy resins (EP), a novel multifunctional organic-inorganic hybrid, melamine-containing polyphosphazene wrapped ammonium polyphosphate (PZMA@APP) with rich amino groups was prepared and used as an efficient flame retardant. Thanks to the cross-linked polyphosphazene part, PZMA@APP exhibited high flame retardant efficiency and smoke suppression to the EP composites. Thermogravimetric analysis indicated that PZMA@APP significantly enhanced the thermal stability of EP composites. The obtained sample passed UL-94 V-0 rating with 10.0wt% addition of PZMA@APP. Notably, inclusion of incorporating PZMA@APP leads to significantly decrease on fire hazards of EP, for instance, bring about a 75.6% maximum decrease in peak heat release rate and 65.9% maximum reduction in total heat release, accompanied with lower smoke production rate and higher graphitized char layer. With regards to mechanical property, the glass transition temperature of EP/PZMA@APP10.0 was as high as 184.5°C. In particular, the addition of PZMA@APP did not worsen the mechanical properties, compared to pure APP. It was confirmed that the participation of melamine-containing polyphosphazene could significantly enhance the quality of char layer and thereby resulting the higher flame retardant efficiency of PZMA@APP. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Non-targeted detection of milk powder adulteration using Raman spectroscopy and chemometrics: melamine case study.

    Science.gov (United States)

    Karunathilaka, Sanjeewa R; Farris, Samantha; Mossoba, Magdi M; Moore, Jeffrey C; Yakes, Betsy Jean

    2017-02-01

    Raman spectroscopy in combination with chemometrics was explored as a rapid, non-targeted screening method for the detection of milk powder (MP) adulteration using melamine as an example contaminant. Raman spectroscopy and an unsupervised pattern-recognition method, principal component analysis (PCA), allowed for the differentiation of authentic MPs from adulterated ones at concentrations > 1.0% for dry-blended (DB) samples and > 0.30% for wet-blended (WB) ones. Soft independent modelling of class analogy (SIMCA), a supervised pattern-recognition method, was also used to classify test samples as adulterated or authentic. Combined statistics at a 97% confidence level from the SIMCA models correctly classified adulteration of MP with melamine at concentrations ≥ 0.5% for DB samples and ≥ 0.30% for WB ones, while no false-positives from authentic MPs were found when the spectra in the 600-700 cm - 1 range were pre-processed using standard normal variate (SNV) followed by a gap-segment derivatisation. The combined technique of Raman spectroscopy and chemometrics proved to be a useful tool for the rapid and cost-efficient non-targeted detection of adulteration in MP at per cent spiking levels.

  3. Melamine modified gold nanoprobe for "on-spot" colorimetric recognition of clonazepam from biological specimens.

    Science.gov (United States)

    Lodha, Anand; Pandya, Alok; Sutariya, Pinkesh G; Menon, Shobhana K

    2013-09-21

    Inexpensive, rapid, and reliable methods of detection are crucial to the control of toxicological investigations. Here we report a highly sensitive, selective and cost effective method for the detection of trace amounts of clonazepam based on gold nanoparticles (AuNPs) in the presence of melamine. Hydrogen bonding interactions between clonazepam and melamine resulted in the aggregation of AuNPs and a consequent color change of AuNPs from wine red to blue. The results showed that the absorption ratio (A636/A552) was linear for clonazepam concentrations in the range of 10 × 10(-8) to 1.0 × 10(-9) M (R(2) = 0.999). The detection limit was 8.9 × 10(-10) M (S/N = 3), which was much lower than that of most existing methods. Coexisting substances including alprazolam, diazepam, nitrazepam and lorazepam did not affect the determination of clonazepam. The sensor developed by this new approach could be used as a spot test and a good alternative means for on-site and real time screening of clonazepam. This proposed scheme was also supported by the use of real samples such as skeletal remains and blood to illustrate the applicability of the developed nanosensor by a series of experiments.

  4. Mechanical properties of melamine formaldehyde microcapsules for self-healing materials

    Energy Technology Data Exchange (ETDEWEB)

    Hu Jianfeng [School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Chen Huanqin [Faculty of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510640 (China); Zhang Zhibing, E-mail: Z.Zhang@bham.ac.uk [School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2009-11-15

    Microcapsules containing a self-healing agent may be incorporated into functional materials to maintain their mechanical strength after a crack is generated. Such microcapsules should have optimum mechanical strength. In this work, microcapsules were formulated by encapsulating dicyclopentadiene (DCPD) with a shell of melamine formaldehyde (MF). The morphology of the microcapsules was characterised using optical microscopy and environmental scanning electron microscopy (ESEM). The shell thickness of the microcapsules was measured using transmission electron microscopy (TEM). Their size distribution was quantified using Malvern particle sizing. Furthermore, their mechanical properties were determined using a micromanipulation technique. Results showed that DCPD was successfully encapsulated by melamine formaldehyde. The mean diameter of the microcapsules varied from 10.7 to 16.0 {mu}m, depending on agitation speed which was used in generation of DCPD (oil)/MF precondenstate (aqueous) emulsion. The mechanical strength parameters including rupture force and nominal rupture stress were found to vary with their size and the reaction time of in situ polymerisation of MF.

  5. Identification of ɛ-caprolactam, melamine and urea in polyvinylpyrrolidone powders by micellar electrokinetic chromatography.

    Science.gov (United States)

    Amini, A

    2014-03-01

    A sodium dodecyl sulfate micellar electrokinetic chromatography (SDS-MEKC) method for the simultaneous separation and identification of ɛ-caprolactam, melamine and urea deliberately added to polyvinylpyrrolidone (povidone) products has been developed. All samples to be analyzed contained paracetamol as an internal marker (IM). The optimized separations were performed in 50mM phosphate buffer (pH 7.0) containing 2% (w/v) sodium dodecyl sulfate (SDS) in fused silica capillaries with UV absorption detection at 200nm. The method was validated with respect to repeatability and intermediate precision, selectivity and robustness with satisfactory results. The relative migration times (RMT) were found to be between 0.03% and 0.13% for intra-day precision and between 0.50% and 0.60% for inter-day precision in four days. The detection limits were determined to be 1.3 (11.5μM), 0.4 (3.5μM) and 41μg/ml (0.4mM) for ɛ-caprolactam, melamine and urea, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. A novel quaternized chitosan-melamine-glutaraldehyde resin for the removal of nitrate and phosphate anions.

    Science.gov (United States)

    Sowmya, Appunni; Meenakshi, Sankaran

    2014-03-01

    A terpolymer of chitosan-melamine-glutaraldehyde was prepared for the first time and it was quaternized with glycidyl trimethyl ammonium chloride (GTMAC). The quaternized chitosan-melamine-glutaraldehyde resin (QCMGR) was found to be effective for the removal of nitrate and phosphate oxyanions. The resin was characterised with FTIR, SEM, EDAX, TGA, DTA, XRD and water regain property. Batch method was followed to optimise the conditions for the removal of nitrate and phosphate. Chemical kinetics of the adsorption was well fitted by pseudo-second order and particle diffusion models and the adsorption process followed the Freundlich isotherm model well. The nitrate and phosphate adsorption capacity of QCMGR from 1000 mg/L respective solutions were 97.5 and 112.5mg/g, respectively. Nitrate and phosphate anions adsorbed effectively on QCMGR by replacing Cl(-) ions at the quaternary ammonium group by exchange mechanism. Even after 10th regeneration cycle the adsorbent fully retained its adsorption efficiency. Nitrate and phosphate removal efficiency of QCMGR was also tested by column method. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Melamine-formaldehyde microcapsules filled sappan dye modified polypropylene composites: encapsulation and thermal properties

    Science.gov (United States)

    Phanyawong, Suphitcha; Siengchin, Suchart; Parameswaranpillai, Jyotishkumar; Asawapirom, Udom; Polpanich, Duangporn

    2018-01-01

    Sappan dye, a natural dye extracted from sappan wood is widely used in cosmetics, textile dyeing and as food additives. However, it was recognized that natural dyes cannot withstand high temperature. In this study, a protective coating of melamine-formaldehyde shell material was applied over the sappan dye to improve its thermal stability. The percentage of sappan dye used in the microencapsulation was 30, 40, 50, 60 and 70 wt%. The color, shape, size, and thermal stability of sappan dye microcapsules were investigated. It was found that increasing amount of sappan dye content in the microcapsules decreased the particle size. Thermal analysis reveals that the melamine-formaldehyde resin served as an efficient protective shell for sappan dye. Besides, 30 wt% sappan dye microcapsules with different weight percent (1, 3 and 5 wt%) of sappan dye was used as modifier for polypropylene (PP). All the prepared composites are red in color which supports the thermal stability of the microcapsules. The changes in crystallinity and melting behavior of PP by the addition of microcapsules were studied in detail by differential scanning calorimetry. Thermogravimetric studies showed that the thermal stability of PP composites increased by the addition of microcapsules.

  8. Graphene-functionalized melamine sponges for microextraction of sulfonamides from food and environmental samples.

    Science.gov (United States)

    Chatzimitakos, Theodoros; Samanidou, Victoria; Stalikas, Constantine D

    2017-11-03

    The study describes the functionalization of melamine sponges with graphene and its use as an adsorbent for the microextraction of sulfonamides from food and environmental samples. The graphene-functionalized melamine sponge (GMeS) was prepared by an easy, one-step procedure, which complies with the principles of green chemistry and is proved advantageous over previously described methods. The applicability of the GMeS in extraction procedures was studied and an analytical method for the determination of sulfonamides in milk, eggs and lake water was developed and validated according to SANCO/12571/2013 guideline. The developed method was highly accurate and reproducible, while the limits of quantification were found to be relatively low (0.31-0.91μgkg -1 , 0.96-1.32μgkg -1 and 0.10-0.29μgL -1 in the case of milk, eggs and lake water respectively). Furthermore, matrix effects were absent in all cases, since the microextraction procedure serves also as a clean-up step. The low cost of synthesis, the environmentally friendly conditions, the efficiency and high extraction recoveries are some additional advantages of the proposed procedure. To the best of our knowledge, this is the first time that a GMeS is prepared in a straightforward way and used for analytical purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Colorimetric sensing of clenbuterol using gold nanoparticles in the presence of melamine.

    Science.gov (United States)

    Zhang, Xiaofang; Zhao, Hong; Xue, Ying; Wu, Zhijiao; Zhang, Yang; He, Yujian; Li, Xiangjun; Yuan, Zhuobin

    2012-04-15

    A highly sensitive method for the detection of trace amount of clenbuterol based on gold nanoparticles (AuNPs) in the presence of melamine was described in this paper. Hydrogen-bonding interaction between clenbuterol and melamine resulted in the aggregation of AuNPs and a consequent color change of AuNPs from wine red to blue. The concentration of clenbuterol could be determined with naked eye or a UV-vis spectrometer. Results showed that the absorption ratio (A(670)/A(520)) was liner with the logarithm of clenbuterol concentration in the range of 2.8×10(-10) to 2.8×10(-7)M and 2.8×10(-7) to 1.4×10(-6)M with linear coefficients of 0.996 and 0.993, respectively. The detection limit was 2.8×10(-11)M (S/N=3), which was much lower than most existing methods. The coexisting substances including dl-epinephrine, phenylalamine, tryptohan, alamine, uric acid, glycine, glycerol, glucose, MgCl(2), CaCl(2) and NaCl did not affect the determination of clenbuterol. The proposed method could be successfully applied to the determination of clenbuterol in human urine. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Adsorption of Paraquat Dichloride by Graphitic Carbon Nitride Synthesized from Melamine Scraps

    Science.gov (United States)

    Watcharenwong, A.; Kaeokan, A.; Rammaroeng, R.; Upama, P.; Kajitvichyanukul, P.

    2017-07-01

    In this research, graphitic carbon nitride (g-C3N4) was synthesized from useless melamine scraps. Mixture of melamine powder and urea was directly burned in the muffle furnace at 550 °C. Later as-synthesized g-C3N4 was modified with hydrochloric acid. The g-C3N4 powder was characterized by several techniques including X-ray diffraction, scanning electron microscope, and specific surface area analyser. Adsorption of the herbicide paraquat from an aqueous solution to suspended particles of g-C3N4 was investigated, taking into consideration several parameters such as initial concentration of paraquat, initial pH, and dosage of g-C3N4. The results showed that with the same amount of g-C3N4, the increase in the paraquat concentration caused the reduction in the removal efficiency and the higher the amount of g-C3N4, the less residual paraquat remained in the bulk solution. G-C3N4 showed better adsorption behaviour in the basic condition. Finally, Langmuir and Freundlich adsorption isotherms were also evaluated. Paraquat adsorption by g-C3N4 was in accordance with Langmuir more than Freundlich adsorption isotherm.

  11. Luminescence enhancement by energy transfer in melamine-Y{sub 2}O{sub 3}:Tb{sup 3+} nanohybrids

    Energy Technology Data Exchange (ETDEWEB)

    Stagi, Luigi, E-mail: luigi.stagi@dsf.unica.it; Chiriu, Daniele; Carbonaro, Carlo M.; Ricci, Pier Carlo [Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, 09042 Monserrato (Italy); Ardu, Andrea; Cannas, Carla [Departimento di Scienze Chimiche e Geologiche and INSTM, Università d Cagliari, SS 554 bivio Sestu, I-09042 Monserrato (Italy)

    2015-09-28

    The phenomenon of luminescence enhancement was studied in melamine-Y{sub 2}O{sub 3}:Tb hybrids. Terbium doped Y{sub 2}O{sub 3} mesoporous nanowires were synthesized by hydrothermal method. X-ray diffraction patterns and Raman scattering spectra testified the realization of a cubic crystal phase. Organic-inorganic melamine-Y{sub 2}O{sub 3}:Tb{sup 3+} hybrid system was successfully obtained by vapour deposition method. Vibration Raman active modes of the organic counterpart were investigated in order to verify the achievement of hybrid system. Photoluminescence excitation and photoluminescence spectra, preformed in the region between 250 and 350 nm, suggest a strong interaction among melamine and Terbium ions. In particular, a remarkable improvement of {sup 5}D{sub 4}→ F{sub J} Rare Earth emission (at about 542 nm) of about 10{sup 2} fold was observed and attributed to an efficient organic-Tb energy transfer. The energy transfer mechanism was studied by the use of time resolved photoluminescence measurements. The melamine lifetime undergoes to a significant decrease when adsorbed to oxide surfaces and it was connected to a sensitization mechanism. The detailed analysis of time decay profile of Terbium radiative recombination shows a variation of double exponential law toward a single exponential one. Its correlation with surface defects and non-radiative recombination was thus discussed.

  12. Development of melamine modified urea formaldehyde resins based o nstrong acidic pH catalyzed urea formaldehyde polymer

    Science.gov (United States)

    Chung-Yun Hse

    2009-01-01

    To upgrade the performance of urea-formaldehyde (UF) resin bonded particleboards, melamine modified urea-formaldehyde (MUF) resins based on strong acidic pH catalyzed UF polymers were investigated. The study was conducted in a series of two experiments: 1) formulation of MUF resins based on a UF polymer catalyzed with strong acidic pH and 2) determination of the...

  13. Thermodynamic stabilities of linear and crinkled tapes and cyclic rosettes in melamine-cyanurate assemblies: a model description

    NARCIS (Netherlands)

    Bielejewska, A.G.; Marjo, Christopher E.; Prins, L.J.; Timmerman, P.; de Jong, Feike; Reinhoudt, David

    2001-01-01

    In this paper we describe model calculations for the self-assembly of N,N-disubstituted melamines 1 and N-substituted cyanuric acid or 5,5-disubstituted barbituric acid derivatives 2 into linear or crinkled tapes and cyclic rosettes via cooperative hydrogen bond formation. The model description

  14. Development of a Specifically Enhanced Enzyme-Linked Immunosorbent Assay for the Detection of Melamine in Milk

    Directory of Open Access Journals (Sweden)

    Yuanming Sun

    2011-06-01

    Full Text Available An indirect competitive enzyme-linked immunosorbent assay (icELISA with enhanced specificity for melamine in milk was developed. Three haptens of melamine with different spacer-arms were used to prepare different plate coating antigens. It was found that the icELISA show best sensitivity and specificity to melamine when using the coating antigen prepared by coupling 3-(4,6-diamino-1,6-dihydro-1,3,5-triazin-2-ylthiopropanoic acid (Hapten C with ovalbumin (OVA. The 50% inhibitory concentration (IC50 value was 35.4 ng·mL−1, the limit of detection (LOD was 8.9 ng·mL−1 and the detectable working range (20–80% inhibitory concentration was from 14.9 to 108.5 ng·mL−1, respectively. Compared to the ELISA results previously reported, the developed icELISA in the present study showed a much lower cross-reactivity to cyromazine, a fly-killing insecticide widely used in vegetables and stables. Recoveries obtained from milk samples in this study were in agreement with those obtained using the HPLC-MS method, indicating the detection performance of the icELISA could meet the requirement of the residue limit set by the Codex Alimentarius Commission. Therefore, the developed immunoassay can be applied for the analysis of melamine presented in milk.

  15. Monoclonal antibody based inhibition ELISA as a new tool for the analysis of melamine in milk and pet food samples.

    Science.gov (United States)

    Zhou, Yu; Li, Chun-Yuan; Li, Yan-Song; Ren, Hong-Lin; Lu, Shi-Ying; Tian, Xiang-Li; Hao, Ya-Ming; Zhang, Yuan-Yuan; Shen, Qing-Feng; Liu, Zeng-Shan; Meng, Xian-Mei; Zhang, Jun-Hui

    2012-12-15

    Stories of recent cases about melamine misuse to raise the false impression of a high protein content of milk in China emerged in September of 2008, have become an international health event. To meet the need for rapid and reliable monitoring of melamine in milk samples, a monoclonal antibody (mAb) was produced and an inhibition enzyme-linked immunosorbent assay (ELISA) was developed based on the mAb. The standard curve was linear in the range from 0.03 to 9 ng mL(-1) with a detection limit (LOD) of 0.01 ng mL(-1). The sensitivity of the assay was 0.35 ng mL(-1). The average recovery values of melamine in the liquid milk, powder milk, dog food and cat food were 99%, 96%, 9% and 98%, respectively and the coefficient of variation (CV) values of all samples were less than 10%. The obtained results showed a potential method as a tool for the rapid and reliable monitoring of melamine in liquid milk and milk powder samples (158 words). Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Nephrolithiasis screening for people with self-perceived exposure to melamine-contaminated milk products in Taipei County, Taiwan

    Directory of Open Access Journals (Sweden)

    Jeng-Cheng Wu

    2017-06-01

    Conclusion: These results suggested that governments can carry out a good risk communication program in relation to melamine-contaminated milk product events, and thus reassure the public as well as allay fears over perceived health risks stemming from such events.

  17. Tailoring two-dimensional PTCDA-melamine self-assembled architectures at room temperature by tuning molecular ratio

    NARCIS (Netherlands)

    Sun, Xiaonan; Jonkman, Harry T.; Silly, Fabien

    2010-01-01

    Engineering and tuning multi-component supramolecular self-assemblies on surfaces is one of the challenges of nanotechnology. We use scanning tunneling microscopy to investigate the influence of molecular ratio on the self-assembly of PTCDA-melamine structures on Au(111)-(22 x root 3). Our

  18. Technical guidelines on testing the migration of primary aromatic amines from polyamide kitchenware and of formaldehyde from melamine kitchenware

    DEFF Research Database (Denmark)

    Simoneau, C.; Hoekstra, E.; Bradley, E.

    of the Regulation (EU) No 284/2011 laying down specific conditions and detailed procedures for the import of polyamide and melamine plastic kitchenware originating in or consigned from [the] People's Republic of China and Hong Kong Special Administrative Region, China. These guidelines have been prepared...

  19. Hydrophilic Molecularly Imprinted Resorcinol-Formaldehyde-Melamine Resin Prepared in Water with Excellent Molecular Recognition in Aqueous Matrices.

    Science.gov (United States)

    Lv, Tianwei; Yan, Hongyuan; Cao, Jiankun; Liang, Shiru

    2015-11-03

    Hydrophilic molecularly imprinted resorcinol-formaldehyde-melamine resin (MIRFM) is synthesized in water and shows excellent molecular recognition in aqueous matrices. The double functional monomers resorcinol and melamine, and the cross-linker formaldehyde, are all hydrophilic, and then the hydrophilic groups (such as hydroxyls, imino groups, and ether linkages) can be introduced into MIRFM, which make the material compatible with aqueous samples. The general principle is demonstrated by the synthesis of MIRFM using sulfanilamide as a dummy template for the selective recognition to sulfonamides (SAs) in milk samples. Resorcinol and melamine can interact with the template mainly by hydrogen bonding and π-π interaction, which makes MIRFM and the analytes have strong affinity. Besides, melamine can improve the rigidity of MIRFM and accelerate the polymerization process, so there is no need to add base or acid as a catalyst, which guarantees the success of molecular imprinting. MIRFM shows higher recovery and improved purification effect for SAs, in comparison to silica, HLB, C18, and SCX. Because of its excellent hydrophilicity and specificity, MIRFM is promising to be applied in biological, environmental, and clinical fields.

  20. Detection of Cyanuric Acid and Melamine in Infant Formula Powders by Mid-FTIR Spectroscopy and Multivariate Analysis

    Directory of Open Access Journals (Sweden)

    Edwin García-Miguel

    2018-01-01

    Full Text Available Chemometric methods using mid-FTIR spectroscopy were developed in order to reduce the time of study of melamine and cyanuric acid in infant formulas. Chemometric models were constructed using the algorithms Partial Least Squares (PLS1, PLS2 and Principal Component Regression (PCR in order to correlate the IR signal with the levels of melamine or cyanuric acid in the infant formula samples. Results showed that the best correlations were obtained using PLS1 (R2: 0.9998, SEC: 0.0793, and SEP: 0.5545 for melamine and R2: 0.9997, SEC: 0.1074, and SEP: 0.5021 for cyanuric acid. Also, the SIMCA model was studied to distinguish between adulterated formulas and nonadulterated samples, giving optimum discrimination and good interclass distances between samples. Results showed that chemometric models demonstrated a good predictive ability of melamine and cyanuric acid concentrations in infant formulas, showing that this is a rapid and accurate technique to be used in the identification and quantification of these adulterants in infant formulas.

  1. Aqueous sulfomethylated melamine gel-forming compositions and methods of use

    Energy Technology Data Exchange (ETDEWEB)

    Meltz, C.N.; Guetzmacher, G.D.; Chang, P.W.

    1989-04-18

    A method is described for the selective modification of the permeability of the strata of a subterranean bydrocarbon-containing reservoir consisting of introducing into a well in, communication with the reservoir; an aqueous gel-forming composition, comprising a 1.0-60.0 weight percent sulfomethylated melamine polymer solution. The solution is prepared with a 1.0 molar equivalent of a malemine, reacted with 3.0-6.7 molar equivalents of formaldehyde or a 2-6 carbon atom containing dialdehyde; 0.25-1.25 molar equivalents of an alkali metal or ammonium salt of surfurous acid; and 0.01-1.5 molar equivalents of a gel-modifying agent.

  2. Continuous temperature-dependent Raman spectroscopy of melamine and structural analog detection in milk powder.

    Science.gov (United States)

    Schmidt, Walter F; Broadhurst, C Leigh; Qin, Jianwei; Lee, Hoyoung; Nguyen, Julie K; Chao, Kuanglin; Hapeman, Cathleen J; Shelton, Daniel R; Kim, Moon S

    2015-03-01

    Hyperspectral Raman imaging has the potential for rapid screening of solid-phase samples for potential adulterants. We can improve mixture analysis algorithms by defining a temperature range in which the contaminant spectrum changes dramatically and uniquely compared with unadulterated material. Raman spectra were acquired for urea, biuret, cyanuric acid, and melamine (pure and at 1% in dried milk powder) from 50 to 310 °C with a gradient of 1 °C min(-1). Adulterants were clearly indentified in the milk powder. Specific frequencies that were mainly associated with ring breathing, stretching, and in-plane deformation shifted with respect to temperature up to 12 cm(-1) in all four molecules. Specific frequencies significantly increased/decreased in intensity within narrow temperature ranges independent of whether the amine was mixed in milk. Correlation of Raman and differential scanning calorimetry data identified structural components and vibrational modes, which concur with or trigger phase transitions.

  3. High-Throughput Platform for Synthesis of Melamine-Formaldehyde Microcapsules.

    Science.gov (United States)

    Çakir, Seda; Bauters, Erwin; Rivero, Guadalupe; Parasote, Tom; Paul, Johan; Du Prez, Filip E

    2017-07-10

    The synthesis of microcapsules via in situ polymerization is a labor-intensive and time-consuming process, where many composition and process factors affect the microcapsule formation and its morphology. Herein, we report a novel combinatorial technique for the preparation of melamine-formaldehyde microcapsules, using a custom-made and automated high-throughput platform (HTP). After performing validation experiments for ensuring the accuracy and reproducibility of the novel platform, a design of experiment study was performed. The influence of different encapsulation parameters was investigated, such as the effect of the surfactant, surfactant type, surfactant concentration and core/shell ratio. As a result, this HTP-platform is suitable to be used for the synthesis of different types of microcapsules in an automated and controlled way, allowing the screening of different reaction parameters in a shorter time compared to the manual synthetic techniques.

  4. A Dimeric Bis(melamine)-Substituted Bispidine for Efficient Transmembrane H+/Cl-Cotransport.

    Science.gov (United States)

    Shinde, Sopan Valiba; Talukdar, Pinaki

    2017-04-03

    A 3,7-diazabicyclo[3.3.1]nonane linking to two melamines is a unique transmembrane H + /Cl - carrier. In the solid state, the V-shaped compound forms a HCl-bound zig-zag network through cooperative protonation and hydrogen bond interactions. In the lipid membrane, the receptor forms a dimeric self-assembly involving multiple H + and Cl - leading to the efficient transport of the acid. The pH-dependent Cl - efflux observed for the compound was rationalized based on a gradual protonation model that confers an active transmembrane carrier at physiological pH. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Ab initio theory for current-induced molecular switching: Melamine on Cu(001)

    KAUST Repository

    Ohto, Tatsuhiko

    2013-05-28

    Melamine on Cu(001) is mechanically unstable under the current of a scanning tunneling microscope tip and can switch among configurations. However, these are not equally accessible, and the switching critical current depends on the bias polarity. In order to explain such rich phenomenology, we have developed a scheme to evaluate the evolution of the reaction paths and activation barriers as a function of bias, which is rooted in the nonequilibrium Green\\'s function method implemented within density functional theory. This, combined with the calculation of the inelastic electron tunneling spectroscopy signal, allows us to identify the vibrational modes promoting the observed molecular conformational changes. Finally, once our ab initio results are used within a resonance model, we are able to explain the details of the switching behavior, such as its dependence on the bias polarity, and the noninteger power relation between the reaction rate constants and both the bias voltage and the electric current. © 2013 American Physical Society.

  6. Study on Flexural Creep Parameters of Overlayed Particleboard by Natural and Melaminated Veneers

    Directory of Open Access Journals (Sweden)

    Abdollah Najafi

    2012-06-01

    Full Text Available In this study, effects of natural and artificial veneer on flexural creep behavior of particleboard was investigated. Particleboard panels were prepared from Pars Neopan industries with 660 kg/m3 density and then overlaid by natural and melamine veneers. Their creep behavior was compared to control particleboard. For evaluating maximum bending load in static flexural test, specimens were cut from panels according to ASTM D 1037 with dimensions of 370×50×16 mm. Then, The flexural creep tests at 20% and 40% of failure bending load was applied to test specimens. Results of flexural tests indicated that the MOR and MOE values of veneered particleboard were highest. Results of creep showed that levels of stresses are effective on all creep parameters, but showed less effect on relative creep. Also, creep parameters less effective on specimens overlaid by natural veneer.

  7. Hapten synthesis and antibody production for the development of a melamine immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Lei Hongtao; Shen Yudong; Song Lijun; Yang Jinyi [Key Laboratory of Food Safety of Guangdong Province/Institute of Food Quality and Safety, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou 510642, Guangdong (China); Chevallier, Olivier P.; Haughey, Simon A. [Institute of Agri-Food and Land Use, Queen' s University Belfast, Belfast BT9 5AG, Northern Ireland (United Kingdom); Wang Hong [Key Laboratory of Food Safety of Guangdong Province/Institute of Food Quality and Safety, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou 510642, Guangdong (China); Sun Yuanming, E-mail: ymsun@scau.edu.cn [Key Laboratory of Food Safety of Guangdong Province/Institute of Food Quality and Safety, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou 510642, Guangdong (China); Elliott, Christopher T., E-mail: chris.elliott@qub.ac.uk [Institute of Agri-Food and Land Use, Queen' s University Belfast, Belfast BT9 5AG, Northern Ireland (United Kingdom)

    2010-04-14

    The incorporation of melamine into food products is banned but its misuse has been widely reported in both animal feeds and food. The development of a rapid screening immunoassay for monitoring of the substance is an urgent requirement. Two haptens of melamine were synthesized by introducing spacer arms of different lengths and structures on the triazine ring of the analyte molecular structure. 6-Aminocaproic acid and 3-mercaptopropionic acid were reacted with 2-chloro-4,6-diamino-1,3,5-triazine (CAAT) to produce hapten 1 [3-(4,6-diamino-1,6-dihydro-1,3,5-triazin-2-ylamino) hexanoic acid] and hapten 2 [3-(4,6-diamino-1,6-dihydro-1,3,5-triazin-2-ylthio) propanoic acid], respectively. The molecular structures of the two haptens were identified by {sup 1}H nuclear magnetic resonance spectrometry, mass spectrometry and infrared spectrometry. An immunogen was prepared by coupling hapten 1 to bovine serum albumin (BSA). Two plate coating antigens were prepared by coupling both haptens to egg ovalbumin (OVA). A competitive indirect enzyme-linked immunosorbent assay (ciELISA) was developed to evaluate homogeneous and heterogeneous assay formats. The results showed that polyclonal antibodies with high titers were obtained, and the heterogeneous immunoassay format demonstrated a better performance with an IC{sub 50} of 70.6 ng mL{sup -1}, a LOD of 2.6 ng mL{sup -1} and a LOQ of 7.6 ng mL{sup -1}. Except for cyromazine, no obvious cross-reactivity to common compounds was found. The data showed that the hapten synthesis was successful and the resultant antisera could be used in an immunoassay for the rapid and sensitive detection of this banned chemical.

  8. Rapid Quantification of Melamine in Different Brands/Types of Milk Powders Using Standard Addition Net Analyte Signal and Near-Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Bang-Cheng Tang

    2016-01-01

    Full Text Available Multivariate calibration (MVC and near-infrared (NIR spectroscopy have demonstrated potential for rapid analysis of melamine in various dairy products. However, the practical application of ordinary MVC can be largely restricted because the prediction of a new sample from an uncalibrated batch would be subject to a significant bias due to matrix effect. In this study, the feasibility of using NIR spectroscopy and the standard addition (SA net analyte signal (NAS method (SANAS for rapid quantification of melamine in different brands/types of milk powders was investigated. In SANAS, the NAS vector of melamine in an unknown sample as well as in a series of samples added with melamine standards was calculated and then the Euclidean norms of series standards were used to build a straightforward univariate regression model. The analysis results of 10 different brands/types of milk powders with melamine levels 0~0.12% (w/w indicate that SANAS obtained accurate results with the root mean squared error of prediction (RMSEP values ranging from 0.0012 to 0.0029. An additional advantage of NAS is to visualize and control the possible unwanted variations during standard addition. The proposed method will provide a practically useful tool for rapid and nondestructive quantification of melamine in different brands/types of milk powders.

  9. Spectroscopic analyses and studies on respective interaction of cyanuric acid and uric acid with bovine serum albumin and melamine

    Science.gov (United States)

    Chen, Dandan; Wu, Qiong; Wang, Jun; Wang, Qi; Qiao, Heng

    2015-01-01

    In this work, the fluorescence quenching was used to study the interaction of cyanuric acid (CYA) and uric acid (UA) with bovine serum albumin (BSA) at two different temperatures (283 K and 310 K). The bimolecular quenching constant (Kq), apparent quenching constant (Ksv), effective binding constant (KA) and corresponding dissociation constant (KD), binding site number (n) and binding distance (r) were calculated by adopting Stern-Volmer, Lineweaver-Burk, Double logarithm and overlap integral equations. The results show that CYA and UA are both able to obviously bind to BSA, but the binding strength order is BSA + CYA < BSA + UA. And then, the interactions of CYA and UA with melamine (MEL) under the same conditions were also studied by using similar methods. The results indicates that both CYA and UA can bind together closely with melamine (MEL). It is wished that these research results would facilitate the understanding the formation of kidney stones and gout in the body after ingesting excess MEL.

  10. Flame-Retardant and Thermal Degradation Mechanism of Caged Phosphate Charring Agent with Melamine Pyrophosphate for Polypropylene

    OpenAIRE

    Lai, Xuejun; Qiu, Jiedong; Li, Hongqiang; Zeng, Xingrong; Tang, Shuang; Chen, Ye; Chen, Zhen

    2015-01-01

    An efficient caged phosphate charring agent named PEPA was synthesized and combined with melamine pyrophosphate (MPP) to flame-retard polypropylene (PP). The effects of MPP/PEPA on the flame retardancy and thermal degradation of PP were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimetric test (CCT), and thermogravimetric analysis (TGA). It was found that PEPA showed an outstanding synergistic effect with MPP in flame retardant PP. When the content of ...

  11. Ag nanoparticle/melamine sulfonic acid supported on silica gel as an efficient catalytic system for synthesis of dihydropyrimidinthiones

    Directory of Open Access Journals (Sweden)

    Parya Nasehi

    2014-07-01

    Full Text Available 3,4-Dihydropyrimidin-2(1H-thiones were synthesized in the presence of Ag nanoparticle/melamine sulfonic acid (MSA supported on silica gel. The reactionwas carried out at 110 oC for 20 min under solvent free conditions. This method hassome advantages such as good yield, mild reaction conditions, ease of operation and work up, short reaction time and high product purity.

  12. Analytical method for the determination of cyromazine and melamine residues in soil using LC-UV and GC-MSD.

    Science.gov (United States)

    Yokley, R A; Mayer, L C; Rezaaiyan, R; Manuli, M E; Cheung, M W

    2000-08-01

    A method is reported for the determination of cyromazine and melamine residues in soil. Soil samples are extracted twice via mechanical shaking, each time with 70% acetonitrile/30% 0.050 M ammomium carbonate for 30 min. An aliquot portion of the pooled extracts is subjected to strong cation exchange (SCX) purification on AG 50W-X4 resin. Final analysis is accomplished using liquid chromatography-ultraviolet (LC-UV) detection at a wavelength of 214 nm. Confirmatory analyses can be performed using gas chromatography-mass selective detection (GC-MSD) in the selected ion monitoring (SIM) mode. The limit of detection (LOD) is 2.5 ng injected and the limit of quantification (LOQ) is 10 ppb when using LC-UV for the analysis of N-cyclopropyl-1,3,5-triazine-2,4, 6-triamine (cyromazine) and 1,3,5-triazine-2,4,6-triamine (melamine). The LOD is 0.050 ng injected and the LOQ is 10 ppb when using GC-MSD for confirmatory analyses. The mean procedural recoveries were 97 and 95% and the standard deviations were 16 and 11% for cyromazine and melamine, respectively (n = 24), when using LC-UV. The mean procedural recoveries were 107 and 92% and the standard deviations were 9.9 and 16% for cyromazine and melamine, respectively (n = 29), when using GC-MSD. The method validation study was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160. The method also passed an Independent Laboratory Validation (ILV) as per U.S. EPA FIFRA Subdivision N.

  13. Three dimensional nitrogen-doped graphene aerogels functionalized with melamine for multifunctional applications in supercapacitors and adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Ling-Bao; Hou, Shu-Fen; Zhou, Jin; Zhang, Jing-Li; Si, Weijiang; Dong, Yunhui, E-mail: hgxydyh@sdut.edu.cn; Zhuo, Shuping, E-mail: zhuosp_academic@yahoo.com

    2015-10-15

    In present work, we demonstrate an efficient and facile strategy to fabricate three-dimensional (3D) nitrogen-doped graphene aerogels (NGAs) based on melamine, which serves as reducing and functionalizing agent of graphene oxide (GO) in an aqueous medium with ammonia. Benefiting from well-defined and cross-linked 3D porous network architectures, the supercapacitor based on the NGAs exhibited a high specific capacitance of 170.5 F g{sup −1} at 0.2 A g{sup −1}, and this capacitance also showed good electrochemical stability and a high degree of reversibility in the repetitive charge/discharge cycling test. More interestingly, the prepared NGAs further exhibited high adsorption capacities and high recycling performance toward several metal ions such as Pb{sup 2+}, Cu{sup 2+} and Cd{sup 2+}. Moreover, the hydrophobic carbonized nitrogen-doped graphene aerogels (CNGAs) showed outstanding adsorption and recycling performance for the removal of various oils and organic solvents. - Graphical abstract: Three-dimensional nitrogen-doped graphene aerogels were prepared by using melamine as reducing and functionalizing agent in an aqueous medium with ammonia, which showed multifunctional applications in supercapacitors and adsorption. - Highlights: • Three-dimensional nitrogen-doped graphene aerogels (NGAs) were prepared. • Melamine was used as reducing and functionalizing agent. • NGAs exhibited relatively good electrochemical properties in supercapacitor. • NGAs exhibited high adsorption performance toward several metal ions. • CNGAs showed outstanding adsorption capacities for various oils and solvents.

  14. A Simple HPLC-DAD Method for the Analysis of Melamine in Protein Supplements: Validation Using the Accuracy Profiles

    Directory of Open Access Journals (Sweden)

    Domenico Montesano

    2013-01-01

    Full Text Available The study presents a fully validated simple high-performance liquid chromatography method with diode array detection (HPLC-DAD, able to accurately determine the melamine, fraudulently added, in protein supplements, commonly used from healthy adults to enhance exercise or sport performance. The validation strategy was intentionally oriented towards routine use and the reliability of the method rather than extreme performance. For this reason, validation by accuracy profile, including estimation of uncertainty, was chosen. This procedure, based on the concept of total error (bias + standard deviation, clearly showed that this method was able to determine melamine over the range of 0.05–3.0 mg Kg−1, selected by taking into account the maximum residue levels (MRLs proposed by European legislation to distinguish between the unavoidable background presence of melamine and unacceptable adulteration. The accuracy profile procedure established that at least 95% of the future results obtained with the proposed method would be within the ±15% acceptance limits of the validated HPLC-DAD method over the whole defined concentration range.

  15. [Rapid determination of melamine in pet food by surface enhanced Raman spectroscopy in combination with Ag nanoparticles].

    Science.gov (United States)

    Cheng, Jie; Su, Xiao-Ou

    2011-01-01

    The rapid qualitative and quantitative analysis of melamine in pet food was realized by surface-enhanced Raman spectroscopy in combination with Ag nanoparticle. In the present study, the 709 and 1 542 cm(-1) Raman shift was chosen as qualitative basis. The quantitative calculation of the concentration range between 1.0 and 10.0 mg x kg(-1) was achieved based on the intensity of 1 149 cm(-1) Raman peak which was used as a normalization standard. The limit of detection was 0.5 mg x kg(-1). The Ag nanoparticle had a strong Raman enhancement effect on melamine and the intensity was affected by the adding time of Ag nanoparticle and the vortex strength. At the same time, the intensity of SERS was affected by the extraction solvent type, and the manner of extraction. The analysis time of each sample was about 5 min. It was so quick that it was easy to realize the rapid detection of melamine in pet food compared with existing methods.

  16. Detection of Melamine in Soybean Meal Using Near-Infrared Microscopy Imaging with Pure Component Spectra as the Evaluation Criteria

    Directory of Open Access Journals (Sweden)

    Zengling Yang

    2016-01-01

    Full Text Available Soybean meal was adulterated with melamine with the purpose of boosting the protein content for unlawful interests. In recent years, the near-infrared (NIR spectroscopy technique has been widely used for guaranteeing food and feed security for its fast, nondestructive, and pollution-free characteristics. However, there are problems with using near-infrared (NIR spectroscopy for detecting samples with low contaminant concentration because of instrument noise and sampling issues. In addition, methods based on NIR are indirect and depend on calibration models. NIR microscopy imaging offers the opportunity to investigate the chemical species present in food and feed at the microscale level (the minimum spot size is a few micrometers, thus avoiding the problem of the spectral features of contaminants being diluted by scanning. The aim of this work was to investigate the feasibility of using NIR microscopy imaging to identify melamine particles in soybean meal using only the pure component spectrum. The results presented indicate that using the classical least squares (CLS algorithm with the nonnegative least squares (NNLS algorithm, without needing first to develop a calibration model, could identify soybean meal that is both uncontaminated and contaminated with melamine particles at as low a level as 50 mg kg−1.

  17. Improvement in photocatalytic H2 evolution over g-C3N4 prepared from protonated melamine

    Science.gov (United States)

    Zhong, Yujiao; Wang, Zhiqiang; Feng, Jianyong; Yan, Shicheng; Zhang, Haitao; Li, Zhaosheng; Zou, Zhigang

    2014-03-01

    Porous g-C3N4 (pm-g-C3N4) samples were prepared by sintering protonated melamine. Photocatalytic activities for H2 production over the g-C3N4 samples were evaluated under visible-light irradiation. Specific surface areas and condensation degree of the g-C3N4 samples prepared from protonated melamine turn larger as the calcination temperatures increase (400 °C, 450 °C, 500 °C, 550 °C, and 580 °C for 1 h). Also, their bandgaps are narrowed and PL peak red shifts, and thus their photocatalytic activities are enhanced. Compared with the reference g-C3N4 samples synthesized by sintering melamine without any protonation (m-g-C3N4), the pm-g-C3N4 samples exhibit better photocatalytic performances, owing to larger specific surface area, less recombination of photogenerated carriers and higher degree of condensation. By optimizing the preparation parameters and the amount of Pt cocatalyst, the highest hydrogen evolution rate of 417 μmol h-1 g-1 was achieved over the pm-g-C3N4 samples synthesized at 550 °C for 2 h, when irradiated by 300-W Xe lamp with a cutoff filter (λ ≥ 420 nm).

  18. Chirality Transfer and Modulation in LB Films Derived From the Diacetylene/Melamine Hydrogen-Bonded Complex.

    Science.gov (United States)

    Zhu, Yu; Xu, Yangyang; Zou, Gang; Zhang, Qijin

    2015-08-01

    Introduction of hydrogen-bonding interaction into π-conjugated systems is a promising strategy, since the highly selective and directional hydrogen-bonding can increase the binding strength, provide enhanced stability to the assemblies, and position the π-conjugated molecules in a desired arrangement. The helical packing of the rigid melamine cores seems to play a dominating role in the subsequent formation of the peripheral helical PDA backbone. The polymerized Langmuir-Blodgett (LB) films exhibited reversible colorimetric and chiroptical changes during repeated heating-cooling cycles, which should be ascribed to the strong hydrogen-bonding interaction between the carboxylic acid and the melamine core. Further, the closely helical packing of the melamine cores could be destroyed upon exposure to HCl or NH(3) gas, whereas the peripheral helical polyaniline and polydiacetylene (PDA) backbone exhibited excellent stability. Although similar absorption changes could be observed for the films upon exposure to HCl or NH(3) gas, their distinct circular dichroism (CD) responses enabled us to distinguish the above two stimuli. © 2015 Wiley Periodicals, Inc.

  19. Enhanced electrochemiluminescence based on Ru(bpy)₃²⁺-doped silica nanoparticles and graphene composite for analysis of melamine in milk

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Limin [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 (China); University of the Chinese Academy of Sciences (China); Huang, Jianshe [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 (China); Yang, Lu; Li, Libo [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 (China); University of the Chinese Academy of Sciences (China); You, Tianyan, E-mail: youty@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 (China)

    2014-05-01

    Highlights: • A sensitive ECL sensor was developed by combining Ru(bpy)₃²⁺-doped silica (Ru(bpy)₃²⁺@SiO₂) nanoparticles with graphene. • The proposed sensor exhibited high sensitivity (~10⁻¹³ M) and wide linear range for melamine. • This method was successfully applied to the detection of melamine in milk. Abstract: A sensitive electrochemiluminescence (ECL) sensor for melamine analysis was fabricated based on Ru(bpy)₃²⁺-doped silica (Ru(bpy)₃²⁺@SiO₂) nanoparticles and graphene composite. Spherical Ru(bpy)₃²⁺@SiO₂ nanoparticles with uniform size about 55 nm were prepared by the reverse microemulsion method. Since per Ru(bpy)₃²⁺@SiO₂ nanoparticle encapsulated a great deal of Ru(bpy)₃²⁺, the ECL intensity has been greatly enhanced, which resulted in high sensitivity. Due to its extraordinary electric conductivity, graphene improved the conductivity and accelerated the electron transfer rate. In addition, graphene could work as electronic channel improving the efficient luminophor amount participating in the ECL reaction, which further enhanced the ECL signal. This proposed sensor was used to melamine analysis and the ECL intensity was proportional to logarithmic melamine concentration range from 1 × 10⁻¹³ M to 1 × 10⁻⁸ M with the detect limit as low as 1 × 10⁻¹³ M. In application to detect melamine in milk, satisfactory recoveries could be obtained, which indicated this sensor having potential application in melamine analysis in real samples.

  20. Directional growth of Ag nanorod from polymeric silver cyanide: A potential substrate for concentration dependent SERS signal enhancement leading to melamine detection

    Science.gov (United States)

    Roy, Anindita; Sahoo, Ramkrishna; Chowdhury, Joydeep; Bhattacharya, Tara Shankar; Agarwal, Ratnesh; Pal, Tarasankar

    2017-08-01

    Attention has been directed to prepare exclusive one-dimensional silver nanostructure from the linear inorganic polymer AgCN. Successive color change from yellow to orange, to red and finally to green reflects the evolution of high yielding Ag nanorods (NRs) from well-known -[Ag-CN]- chains of polymeric AgCN at room temperature. The parental 1D morphology of AgCN is retained within the as-synthesized Ag NRs. So we could successfully exploit the Ag NR for surface-enhanced Raman scattering (SERS) studies for sensing a popular milk adulterant melamine down to picomolar level. We observed interesting concentration dependent selective SERS band enhancement of melamine. The enhanced 1327 cm- 1 SERS signal intensity at lower concentration (10- 9 and 10- 12 M) of melamine speaks for the preferential participation of -C-N of melamine molecule with Ag surface. On the other hand, '-NH2' group together with ring 'N' participation of melamine molecule onto Ag surface suggested an adsorptive stance at higher (10- 3-10- 7 M) concentration range. Thus the binding modes of the molecule at the Ag surface justify its fluxional behavior.

  1. Electrospun melamine resin-based multifunctional nonwoven membrane for lithium ion batteries at the elevated temperatures

    Science.gov (United States)

    Wang, Qingfu; Yu, Yong; Ma, Jun; Zhang, Ning; Zhang, Jianjun; Liu, Zhihong; Cui, Guanglei

    2016-09-01

    A flame retardant and thermally dimensional stable membrane with high permeability and electrolyte wettability can overcome the safety issues of lithium ion batteries (LIBs) at elevated temperatures. In this work, a multifunctional thermoset nonwoven membrane composed of melamine formaldehyde resin (MFR) nano-fibers was prepared by a electro-spinning method. The resultant porous nonwoven membrane possesses superior permeability, electrolyte wettability and thermally dimensional stability. Using the electrospun MFR membrane, the LiFePO4/Li battery exhibits high safety and stable cycling performance at the elevated temperature of 120 °C. Most importantly, the MFR membrane contains lone pair electron in the nitrogen element, which can chelate with Mn2+ ions and suppress their transfer across the separator. Therefore, the LiMn2O4/graphite cells with the electrospun MFR multifunctional membranes reveal an improved cycle performance even at high temperature. This work demonstrated that electrospun MFR is a promising candidate material for high-safety separator of LIBs with stable cycling performance at elevated temperatures.

  2. Investigation of melamine derived quaternary as ammonium salt potential shale inhibitor

    Science.gov (United States)

    Yu, Hongjiang; Hu, Weimin; Guo, Gang; Huang, Lei; Li, Lili; Gu, Xuefan; Zhang, Zhifang; Zhang, Jie; Chen, Gang

    2017-06-01

    Melamine, sodium chloroacetate and sodium hydroxide were used as raw materials to synthesize a kind of neutral quaternary ammonium salt (NQAS) as potential clay swelling inhibitor and water-based drilling fluid additive, and the reaction conditions were screened based on the linear expansion rate of bentonite. The inhibitive properties of NQASs were investigated by various methods, including montmorillonite (MMT) linear expansion test, mud ball immersing test, particle distribution measurement, thermogravimetric analysis and scanning electron microscopy etc. The results indicate that NQAS can inhibit expansion and dispersion of clay in water effectively. At the same condition, the bentonite linear expansion rate in NQAS-6 solution is much lower than those of others, and the hydration expansion degree of the mud ball in 0.5% NQAS-6 solution is appreciably weaker than the control test. The compatibility test indicates NQAS-6 could be compatible with the conventional additives in water-based drilling fluids, and the temperature resistance of modified starch was improved effectively. Meanwhile, the inhibitive mechanism was discussed through the particle distribution measurement.

  3. Thermal Plasma Synthesis of Crystalline Gallium Nitride Nanopowder from Gallium Nitrate Hydrate and Melamine

    Directory of Open Access Journals (Sweden)

    Tae-Hee Kim

    2016-02-01

    Full Text Available Gallium nitride (GaN nanopowder used as a blue fluorescent material was synthesized by using a direct current (DC non-transferred arc plasma. Gallium nitrate hydrate (Ga(NO33∙xH2O was used as a raw material and NH3 gas was used as a nitridation source. Additionally, melamine (C3H6N6 powder was injected into the plasma flame to prevent the oxidation of gallium to gallium oxide (Ga2O3. Argon thermal plasma was applied to synthesize GaN nanopowder. The synthesized GaN nanopowder by thermal plasma has low crystallinity and purity. It was improved to relatively high crystallinity and purity by annealing. The crystallinity is enhanced by the thermal treatment and the purity was increased by the elimination of residual C3H6N6. The combined process of thermal plasma and annealing was appropriate for synthesizing crystalline GaN nanopowder. The annealing process after the plasma synthesis of GaN nanopowder eliminated residual contamination and enhanced the crystallinity of GaN nanopowder. As a result, crystalline GaN nanopowder which has an average particle size of 30 nm was synthesized by the combination of thermal plasma treatment and annealing.

  4. Preparation of nitrogen-doped carbon nanotubes with different morphologies from melamine-formaldehyde resin.

    Science.gov (United States)

    Yao, Yi; Zhang, Bingqing; Shi, Jingying; Yang, Qihua

    2015-04-08

    We report a facile method for the synthesis of nitrogen-doped carbon nanotubes (NCNTs) from melamine-formaldehyde (MR) resin using FeCl3 or supported FeCl3 as catalysts. The growth of NCNTs follows a decomposition-reconstruction mechanism, in which the polymer precursor would totally gasify during pyrolysis process and then transformed into carbon nanotubes. The morphology of the NCNTs could be adjusted via applying different catalyst supports and three kinds of carbon nanotubes with outer-diameter of 20-200 nm and morphologies of either bamboo-like or hollow interiors were obtained. Nitrogen atoms in the materials were mainly in the form of pyridinic and quaternary form while the formation of iron species strongly depended on the interaction between iron precursor and organic carbon/nitrogen sources. All MR resin derived NCNTs are efficient toward oxygen reduction reaction (ORR). NCNTs prepared using FeCl3 as catalyst showed the highest ORR activity with half-wave potentials of -0.17 V, which is comparable with commercial Pt/C. This is probably because of a close contact between MR resin and iron precursor could enhance the iron-ligand coordination strength and thus steadily improve the performance of the catalyst.

  5. Electrical Conductivity Properties of Newly Synthesized Melamine - Aniline - Formaldehyde Terpolymer and its Polychelate

    Directory of Open Access Journals (Sweden)

    K. P. Dharkar

    2011-01-01

    Full Text Available Terpolymer MAF synthesized by the polycondensation of melamine (M and aniline (A with formaldehyde (F in the presence of an acid catalyst in 1:1:3 molar proportions of the reacting monomers. Polychelates were prepared by using metal acetate, metal salts and MAF ligand in DMF medium. The prepared terpolymer and its polychelates were characterized by using elemental analysis, magnetic studies and spectral analysis. In the present paper, electrical conductivity properties of the terpolymer and its polychelates were studied over a wide range of temperature and is in the order MAF

  6. Flame Retardancy of PA6 Using a Guanidine Sulfamate/Melamine Polyphosphate Mixture

    Directory of Open Access Journals (Sweden)

    Mathieu Coquelle

    2015-02-01

    Full Text Available Polyamide 6 (PA6 is a widely-used polymer that could find applications in various sectors, including home textiles, transportation or construction. However, due to its organic nature, PA6 is flammable, and flame-retardant formulations have to be developed to comply with fire safety standards. Recently, it was proposed to use ammonium sulfamate as an effective flame retardant for PA6, even at low loading content. However, processing issues could occur with this additive considering large-scale production. This paper thus studies the use of another sulfamate salt—guanidine sulfamate (GAS—and evidences its high efficiency when combined with melamine polyphosphate (MPP as a flame retardant for PA6. A decrease of the peak of the heat release rate by 30% compared to pure PA6 was obtained using only 5 wt% of a GAS/MPP mixture in a microscale calorimeter. Moreover, PA6 containing the mixture GAS/MPP exhibits a Limiting Oxygen Index (LOI of 37 vol% and is rated V0 for the UL 94 test (Vertical Burning Test; ASTM D 3801. The mechanisms of degradation were investigated analyzing the gas phase and solid phase when the material degrades. It was proposed that MPP and GAS modify the degradation pathway of PA6, leading to the formation of nitrile end-group-containing molecules. Moreover, the formation of a polyaromatic structure by the reaction of MPP and PA6 was also shown.

  7. Synthesis and characterization of nitrogen-doped carbon nanotubes by pyrolysis of melamine

    Science.gov (United States)

    Li, Xuefei; Kong, Lingnan; Yang, Jinghai; Gao, Ming; Hu, Tingjing; Wu, Xingtong; Li, Ming

    2013-11-01

    The typical bamboo-like nitrogen doped carbon nanotubes (N-CNTs) have been successfully synthesized via pyrolysis of melamine (C3N6H6). The morphology of the samples is characterized by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The synthesized nanotubes are structurally uniform. The nitrogen to carbon atomic ratio of N-CNTs determined by chemical element analysis is found to be 0.23. The corresponding binding energy of the samples is obtained through X-ray photoelectron spectroscopy (XPS) and the characteristic infrared peaks are recorded by using Fourier transform infrared spectroscopy (FTIR). The characterization of thermal stability is obtained by thermo-gravimetric analysis (TGA) under flowing argon. The photoluminescence (PL) spectrum of the product shows that all the emission peaks are located in the blue-violet wavelength region, which indicates that N-CNTs may have potential applications in nano-optical device fields. Moreover, the growth mechanism of N-CNTs is carefully discussed.

  8. Preparation of CMC-modified melamine resin spherical nano-phase change energy storage materials.

    Science.gov (United States)

    Hu, Xiaofeng; Huang, Zhanhua; Zhang, Yanhua

    2014-01-30

    A novel carboxymethyl cellulose (CMC)-modified melamine-formaldehyde (MF) phase change capsule with excellent encapsulation was prepared by in situ polymerization. Effects of CMC on the properties of the capsules were studied by Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). The results showed that the CMC-modified capsules had an average diameter of about 50nm and good uniformity. The phase change enthalpy of the capsules was increased and the cracking ratio decreased by incorporating a suitable amount of CMC. The optimum phase change enthalpy of the nanocapsules was 83.46J/g, and their paraffin content was 63.1%. The heat resistance of the capsule shells decreased after CMC modification. In addition, the nanocapsule cracking ratio of the nanocapsules was 11.0%, which is highly attractive for their application as nano phase change materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Investigation on the Stability of Derivative Melam from Melamine Pyrolysis under High Pressure

    Directory of Open Access Journals (Sweden)

    Xiaohong Yuan

    2018-03-01

    Full Text Available Although various kinds of carbon nitride precursors have been proposed, s-triazine-based structures are hardly reported because of their unfavorable energy, higher than that of heptazine-based ones. In this study, we investigate the thermal stability of s-triazine-based melam processed at a high pressure of 5 GPa and a temperature of 400–700 °C and complete the analyses of the composition and structure of the treated samples through X-ray diffraction (XRD, Fourier-transform infrared spectroscopy (FTIR, and elemental analyses (EA. Results show that melam can stably exist up to 600 °C at 5 GPa. XRD and FTIR analyses reveal that residual melamine can be pyrolyzed into melam as temperature increases from 400 °C to 600 °C at a high pressure, suggesting that melam may be purified through high-pressure pyrolysis. Further melam polymerization at a higher pressure is a promising strategy for the preparation of s-triazine-based carbon nitride precursors used for bulk carbon nitride synthesis.

  10. Investigation on the Stability of Derivative Melam from Melamine Pyrolysis under High Pressure.

    Science.gov (United States)

    Yuan, Xiaohong; Luo, Kun; Wu, Yingju; He, Julong; Zhao, Zhisheng; Yu, Dongli

    2018-03-18

    Although various kinds of carbon nitride precursors have been proposed, s-triazine-based structures are hardly reported because of their unfavorable energy, higher than that of heptazine-based ones. In this study, we investigate the thermal stability of s-triazine-based melam processed at a high pressure of 5 GPa and a temperature of 400-700 °C and complete the analyses of the composition and structure of the treated samples through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and elemental analyses (EA). Results show that melam can stably exist up to 600 °C at 5 GPa. XRD and FTIR analyses reveal that residual melamine can be pyrolyzed into melam as temperature increases from 400 °C to 600 °C at a high pressure, suggesting that melam may be purified through high-pressure pyrolysis. Further melam polymerization at a higher pressure is a promising strategy for the preparation of s-triazine-based carbon nitride precursors used for bulk carbon nitride synthesis.

  11. Impairment of cognitive function and synaptic plasticity associated with alteration of information flow in theta and gamma oscillations in melamine-treated rats.

    Directory of Open Access Journals (Sweden)

    Xiaxia Xu

    Full Text Available Changes of neural oscillations at a variety of physiological rhythms are effectively associated with cognitive performance. The present study investigated whether the directional indices of neural information flow (NIF could be used to symbolize the synaptic plasticity impairment in hippocampal CA3-CA1 network in a rat model of melamine. Male Wistar rats were employed while melamine was administered at a dose of 300 mg/kg/day for 4 weeks. Behavior was measured by the Morris water maze(MWMtest. Local field potentials (LFPs were recorded before long-term potentiation (LTP induction. Generalized partial directed coherence (gPDC and phase-amplitude coupling conditional mutual information (PAC_CMI were used to measure the unidirectional indices in both theta and low gamma oscillations (LG, ~ 30-50 Hz. Our results showed that melamine induced the cognition deficits consistent with the reduced LTP in CA1 area. Phase locking values (PLVs showed that the synchronization between CA3 and CA1 in both theta and LG rhythms was reduced by melamine. In both theta and LG rhythms, unidirectional indices were significantly decreased in melamine treated rats while a similar variation trend was observed in LTP reduction, implying that the effects of melamine on cognitive impairment were possibly mediated via profound alterations of NIF on CA3-CA1 pathway in hippocampus. The results suggested that LFPs activities at these rhythms were most likely involved in determining the alterations of information flow in the hippocampal CA3-CA1 network, which might be associated with the alteration of synaptic transmission to some extent.

  12. Dose–response assessment of nephrotoxicity from a twenty-eight-day combined-exposure to melamine and cyanuric acid in F344 rats

    International Nuclear Information System (INIS)

    Gamboa da Costa, Gonçalo; Jacob, Cristina C.; Von Tungeln, Linda S.; Hasbrouck, Nicholas R.; Olson, Greg R.; Hattan, David G.; Reimschuessel, Renate; Beland, Frederick A.

    2012-01-01

    The adulteration of pet food with melamine and derivatives, including cyanuric acid, has been implicated in the kidney failure and death of cats and dogs in the USA and other countries. In a previous 7-day dietary study in F344 rats, we established a no-observed-adverse-effect level (NOAEL) for a co-exposure to melamine and cyanuric acid of 8.6 mg/kg bw/day of each compound, and a benchmark dose lower confidence limit (BMDL) of 8.4–10.9 mg/kg bw/day of each compound. To ascertain the role played by the duration of exposure, we treated F344 rats for 28 days. Groups of male and female rats were fed diet containing 0 (control), 30, 60, 120, 180, 240, or 360 ppm of both melamine and cyanuric acid. The lowest dose that produced histopathological alterations in the kidney was 120 ppm, versus 229 ppm in the 7-day study. Wet-mount analysis of kidney sections demonstrated the formation of melamine cyanurate spherulites in one male and two female rats at the 60 ppm dose and in one female rat at the 30 ppm dose, establishing a NOAEL of 2.1 mg/kg bw/day for males and < 2.6 mg/kg bw/day for females, and BMDL values as low as 1.6 mg/kg bw/day for both sexes. These data demonstrate that the length of exposure is an important component in the threshold of toxicity from a co-exposure to these compounds and suggest that the current risk assessments based on exposures to melamine alone may not reflect sufficiently the risk of a co-exposure to melamine and cyanuric acid. -- Highlights: ► A 28-day dietary co-exposure to melamine and cyanuric acid was conducted in F344 rats. ► The NOAELs were 2.1 mg/kg bw/day for males and < 2.6 mg/kg bw/day for females. ► BMDL values as low as 1.6 mg/kg bw/day for both sexes were determined. ► The length of exposure plays an important role in the threshold of toxicity. ► Current assessments may underestimate the risk of melamine and cyanuric acid.

  13. Dose–response assessment of nephrotoxicity from a twenty-eight-day combined-exposure to melamine and cyanuric acid in F344 rats

    Energy Technology Data Exchange (ETDEWEB)

    Gamboa da Costa, Gonçalo, E-mail: goncalo.gamboa@fda.hhs.gov [Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079 (United States); Jacob, Cristina C.; Von Tungeln, Linda S. [Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079 (United States); Hasbrouck, Nicholas R. [Center for Veterinary Medicine, Laurel, MD 20708 (United States); Olson, Greg R. [Toxicologic Pathology Associates, Jefferson, AR 72079 (United States); Hattan, David G. [Center for Food Safety and Applied Nutrition, College Park, MD 20740 (United States); Reimschuessel, Renate [Center for Veterinary Medicine, Laurel, MD 20708 (United States); Beland, Frederick A. [Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079 (United States)

    2012-07-15

    The adulteration of pet food with melamine and derivatives, including cyanuric acid, has been implicated in the kidney failure and death of cats and dogs in the USA and other countries. In a previous 7-day dietary study in F344 rats, we established a no-observed-adverse-effect level (NOAEL) for a co-exposure to melamine and cyanuric acid of 8.6 mg/kg bw/day of each compound, and a benchmark dose lower confidence limit (BMDL) of 8.4–10.9 mg/kg bw/day of each compound. To ascertain the role played by the duration of exposure, we treated F344 rats for 28 days. Groups of male and female rats were fed diet containing 0 (control), 30, 60, 120, 180, 240, or 360 ppm of both melamine and cyanuric acid. The lowest dose that produced histopathological alterations in the kidney was 120 ppm, versus 229 ppm in the 7-day study. Wet-mount analysis of kidney sections demonstrated the formation of melamine cyanurate spherulites in one male and two female rats at the 60 ppm dose and in one female rat at the 30 ppm dose, establishing a NOAEL of 2.1 mg/kg bw/day for males and < 2.6 mg/kg bw/day for females, and BMDL values as low as 1.6 mg/kg bw/day for both sexes. These data demonstrate that the length of exposure is an important component in the threshold of toxicity from a co-exposure to these compounds and suggest that the current risk assessments based on exposures to melamine alone may not reflect sufficiently the risk of a co-exposure to melamine and cyanuric acid. -- Highlights: ► A 28-day dietary co-exposure to melamine and cyanuric acid was conducted in F344 rats. ► The NOAELs were 2.1 mg/kg bw/day for males and < 2.6 mg/kg bw/day for females. ► BMDL values as low as 1.6 mg/kg bw/day for both sexes were determined. ► The length of exposure plays an important role in the threshold of toxicity. ► Current assessments may underestimate the risk of melamine and cyanuric acid.

  14. Combination effect of melamine polyphosphate and graphene on flame retardant properties of poly(vinyl alcohol)

    International Nuclear Information System (INIS)

    Huang Guobo; Liang Huading; Wang Yong; Wang Xu; Gao Jianrong; Fei Zhengdong

    2012-01-01

    Highlights: ► PVA/graphene/MPP composites were prepared by solvent blending. ► PVA/graphene systems improved the flame retardancy of the nanocomposites. ► Flame retardation mechanism was explained by SEM, FT-IR and XPS. - Abstract: A novel flame retardant poly(vinyl alcohol) (PVA)/melamine polyphosphate (MPP)–graphene nanocomposite has been prepared by solvent blending. Results from X-ray diffraction (XRD) and transmission electron microscopy (TEM) suggest that an excellent dispersion of exfoliated graphene and MPP in the PVA matrix was achieved. The thermal and flammability properties of the nanocomposite were investigated using thermogravimetry, cone calorimetry, and flammability tests (UL 94 and LOI). The presence of both MPP and graphene in the polymer matrix led to an enhanced thermal stability and significantly reduced flammability for the nanocomposite. PVA composites filled with 10 wt% MPP and 1 wt% graphene (PVA/G1/MPP10) achieved the LOI value of 29.6 and UL-94 V0 grade. Compared to pure PVA, the peak heat release rate (PHRR) of PVA/G1/MPP10 is reduced by about 60%. Meanwhile, the mechanical properties of PVA/G1/MPP10 composites exhibit almost no deterioration compared with pure PVA. The morphology and composition of residues generated after cone calorimeter tests were investigated by scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The SEM images showed the compact and dense intumescent char jammed with graphene sheets was formed for PVA/G1/MPP10 during combustion. The results of XPS confirmed that carbon content of the char for PVA/G1/MPP10 is increased obviously by the combination effect of the flame retardant MPP and graphene.

  15. Mesoporous carbon adsorbents from melamine-formaldehyde resin using nanocasting technique for CO2 adsorption.

    Science.gov (United States)

    Goel, Chitrakshi; Bhunia, Haripada; Bajpai, Pramod K

    2015-06-01

    Mesoporous carbon adsorbents, having high nitrogen content, were synthesized via nanocasting technique with melamine-formaldehyde resin as precursor and mesoporous silica as template. A series of adsorbents were prepared by varying the carbonization temperature from 400 to 700°C. Adsorbents were characterized thoroughly by nitrogen sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), elemental (CHN) analysis, Fourier transform infrared (FTIR) spectroscopy and Boehm titration. Carbonization temperature controlled the properties of the synthesized adsorbents ranging from surface area to their nitrogen content, which play major role in their application as adsorbents for CO2 capture. The nanostructure of these materials was confirmed by XRD and TEM. Their nitrogen content decreased with an increase in carbonization temperature while other properties like surface area, pore volume, thermal stability and surface basicity increased with the carbonization temperature. These materials were evaluated for CO2 adsorption by fixed-bed column adsorption experiments. Adsorbent synthesized at 700°C was found to have the highest surface area and surface basicity along with maximum CO2 adsorption capacity among the synthesized adsorbents. Breakthrough time and CO2 equilibrium adsorption capacity were investigated from the breakthrough curves and were found to decrease with increase in adsorption temperature. Adsorption process for carbon adsorbent-CO2 system was found to be reversible with stable adsorption capacity over four consecutive adsorption-desorption cycles. From three isotherm models used to analyze the equilibrium data, Temkin isotherm model presented a nearly perfect fit implying the heterogeneous adsorbent surface. Copyright © 2015. Published by Elsevier B.V.

  16. Relationship Between Milk Adulterated With Melamine and the Appearance of Renal Stones in a Childhood Population: A Review of the Literature of the Cases That Occurred in the People’s Republic of China

    Directory of Open Access Journals (Sweden)

    Jasmina Bordón-González

    2014-05-01

    Full Text Available Introduction: Melamine is a chemical substance used in the production of resins. When melamine is added to milk, nitrogen concentration increases, which suggest an increase the amount of false proteins and consequently causing kidney diseases in some population subgroups. The objective of this study is to document the possible connection in between adulterated industrial milk with melamine and the appearance of kidney stones in children under 12 years old by reviewing cases occurred in the People’s Republic of China.Material and methods: A literature review was carried out on articles published on dated between 2005-2010, and an extensive analysis was made on the results found.Results: A total of 20 articles were reviewed, of which 11 met the criteria for inclusion, There were 9 cross-sectional studies, one follow-up study and a case-control study. Four studies calculated odds ratio (OR in their analysis to evaluate the relative risk of having stones in those children exposed to melamine formula. In the case-control study, children exposed to melamine formula were 5.17 times as likely to have kidney stones as children exposed to a non-melamine formula (95% confidence interval, 3.28-8.14; P<.001.Conclusions: Melamine adulteration in milk is a preventable public health issue which suggests the establishing of greater control measures and the implementation of food regulations by the food industry and Health and Food Institutions.

  17. Modification and evaluation of thermal properties of melamine-formaldehyde/n-eicosane microcapsules for thermo-regulation applications

    International Nuclear Information System (INIS)

    Mohaddes, F.; Islam, S.; Shanks, R.; Fergusson, M.; Wang, L.; Padhye, R.

    2014-01-01

    A modified process to enhance the latent heat of fusion of n-eicosane microcapsules in melamine-formaldehyde shells is suggested for application in textiles. Deviations in melt enthalpy and phase change temperatures were determined for produced microcapsules by differential scanning calorimetry. Thermo-regulation efficiency of eicosane-microcapsule-treated fabrics was evaluated via fitting the Newton cooling law to the experimental data, and a new constant, α, was defined as the thermal delay factor. Scanning electron microscopy images and particle size distribution analysis were consistent and the particle size was found to be between 0.5 and 2.7 μm. Melamine-formaldehyde/n-eicosane microcapsule composition was confirmed using a Fourier transform infrared spectrophotometry. The microcapsules developed showed excellent heat storage capacities, over 162.4 J/g, over melting and crystallisation ranges compared with previous studies undertaken in this field. - Highlights: • Modified eicosane microcapsules with the highest phase change enthalpies were made. • Newton cooling law was fitted to determine thermal delay in PCM-substrates. • Fine microcapsule units with diameters less than 0.5 μm were prepared. • All pliable PCM-substrates can be thermally assessed using thermal logging method

  18. Poly(melamine-formaldehyde) microcapsules filled with epoxy resin: effect of M/F ratio on the shell wall stability

    Science.gov (United States)

    Sharma, Shilpi; Choudhary, Veena

    2017-07-01

    In this article, we systematically investigated the effects of process parameters such as melamine to formaldehyde (M/F) ratio taken in the initial feed on the yield percent, core content, solvent wash stability, morphology, mean particle size distribution and thermal stability of the microcapsules. Epoxy loaded poly(melamine-formaldehyde) (PMF) microcapsules were prepared by in situ polymerization using emulsion technique. Capsules core content and solvent wash stability increased as the formaldehyde content increased. Structural (FTIR and 1H-NMR), morphological (optical microscopy (OM) and scanning electron microscopy (SEM)) and thermal (thermogravimetry and differential scanning calorimetry) characterization was done to investigate the effects of M/F ratio on the synthesized microcapsules. The analysis of core material by FTIR and 1H-NMR spectra confirmed the presence of epoxy as the core material. OM and SEM micrographs showed that the prepared capsules were almost spherical with a perfect periphery, but showed the tendency to agglomerate as the ratio of M/F decreased. The mean particle size of epoxy filled PMF microcapsules decreased (from 87.1 µm to 67 µm) as the ratio of M/F increased. Thermal analysis showed that the microcapsules were thermally stable up to 373 °C. Thermal stability of microcapsules increased as the ratio of M/F increased. Such microcapsules are expected to find applications in the preparation of polymeric self-healing composites for aerospace industry.

  19. The application of Near-Infrared Reflectance Spectroscopy (NIRS) to detect melamine adulteration of soya bean meal.

    Science.gov (United States)

    Haughey, Simon A; Graham, Stewart F; Cancouët, Emmanuelle; Elliott, Christopher T

    2013-02-15

    Soya bean products are used widely in the animal feed industry as a protein based feed ingredient and have been found to be adulterated with melamine. This was highlighted in the Chinese scandal of 2008. Dehulled soya (GM and non-GM), soya hulls and toasted soya were contaminated with melamine and spectra were generated using Near Infrared Reflectance Spectroscopy (NIRS). By applying chemometrics to the spectral data, excellent calibration models and prediction statistics were obtained. The coefficients of determination (R(2)) were found to be 0.89-0.99 depending on the mathematical algorithm used, the data pre-processing applied and the sample type used. The corresponding values for the root mean square error of calibration and prediction were found to be 0.081-0.276% and 0.134-0.368%, respectively, again depending on the chemometric treatment applied to the data and sample type. In addition, adopting a qualitative approach with the spectral data and applying PCA, it was possible to discriminate between the four samples types and also, by generation of Cooman's plots, possible to distinguish between adulterated and non-adulterated samples. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Gold-sputtered Blu-ray discs: simple and inexpensive SERS substrates for sensitive detection of melamine.

    Science.gov (United States)

    Nieuwoudt, Michél K; Martin, Jacob W; Oosterbeek, Reece N; Novikova, Nina I; Wang, Xindi; Malmström, Jenny; Williams, David E; Simpson, M Cather

    2016-06-01

    Nanostructured gold substrates provide chemically stable, signal-enhancing substrates for the sensitive detection of a variety of compounds through surface-enhanced Raman spectroscopy (SERS). Recent developments in advanced fabrication methods have enabled the manufacture of SERS substrates with repeatable surface nanostructures that provide reproducible quantitative analysis, historically a weakness of the SERS technique. Here, we describe the novel use of gold-sputtered Blu-ray disc surfaces as SERS substrates. The unique surface features and composition of the Blu-ray disc recording surface lead to the formation of gold nano-islands and nanogaps following simple gold sputtering, without any background peaks from the substrate. The SERS performance of this substrate is strong and reproducible with an enhancement factor (EF) of 10(3) for melamine. A limit of detection (LOD) for this compound of 70 ppb and average reproducibility of ±12 % were achieved. Gold-sputtered Blu-ray discs thus offer an excellent alternative to more exotic gold SERS substrates prepared by advanced, time-consuming and expensive methods. Graphical abstract AFM 3D images of 1-μm(2) sections of uncoated and gold-sputtered recordable Blu-ray disc (BD-R) surfaces and the SERS signal obtained on the gold-sputtered surface for a 1000 ppm aqueous solution of melamine.

  1. Stacking and Analysis of Melamine in Milk Products with Acetonitrile-Salt Stacking Technique in Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Yu Kong

    2014-01-01

    Full Text Available Melamine was measured in real milk products with capillary electrophoresis (CE based on acetonitrile-salt stacking (ASS method. Real milk samples were deproteinized with acetonitrile at a final concentration of 60% (v/v and then injected hydrodynamically at 50 mBar for 40.0 s. The optimized buffer contains 80.0 mmol/L pH 2.8 phosphates. Melamine could be detected within 20.0 min at +10 kV with a low limit of detection (LOD of 0.03 μmol/L. Satisfactory reproducibility (inter- and intraday RSD% both for migration time and peak area was lower than 5.0% and a wide linearity range of 0.05 μmol/L ~ 10.0 μmol/L were achieved. The proposed method was suitable for routine assay of MEL in real milk samples that was subjected to a simple treatment step.

  2. Water-based chitosan/melamine polyphosphate multilayer nanocoating that extinguishes fire on polyester-cotton fabric.

    Science.gov (United States)

    Leistner, Marcus; Abu-Odeh, Anas A; Rohmer, Sarah C; Grunlan, Jaime C

    2015-10-05

    Polyester-cotton (PECO) blends are widely used in the textile industry because they combine the softness of cotton and the strength and durability of polyester. Unfortunately, both fiber types share the disadvantage of being flammable. The layer-by-layer coating technique was used to deposit a highly effective flame retardant (melamine polyphosphate) from water onto polyester-cotton fabric. Soluble melamine and sodium hexametaphosphate form this water-insoluble flame retardant during the coating procedure. This unique nanocoating imparts self-extinguishing properties to PECO with only 12% relative coating weight. Vertical flame testing, pyrolysis combustion flow calorimetry (PCFC), thermogravimetric analysis (TGA), and scanning electron microscopy were used to evaluate the quality of the coating as well as its flame retardant performance. A combination of both condensed and gas-phase activity appears to be the reason for this effective flame retardancy. Degradation pathways of both cotton and polyester are affected by the applied coating, as shown by PCFC and TGA. Use of environmentally benign and non-toxic chemicals, and the ease of layer-by-layer deposition, making this coating an industrially feasible alternative to render polyester-cotton fabric self-extinguishing. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Epitaxial ordering of a perylenetetracarboxylic diimide-melamine supramolecular network driven by the Au(111)-(22x root 3) reconstruction

    NARCIS (Netherlands)

    Silly, Fabien; Shaw, Adam Q.; Briggs, G. A. D.; Castell, Martin R.

    2008-01-01

    Substrate mediated ordering and intermolecular interactions are used to create a long-range supramolecular network of perylenetetracarboxylic diimide and melamine on a reconstructed Au(111)-(22x root 3) surface. Scanning tunneling microscopy reveals that the network is composed of a succession of

  4. Dual protection of wood surface treated with melamine-modified urea-formaldehyde resin mixed with ammonium polyphosphate against both fire and decay

    Science.gov (United States)

    Xing-xia Ma; Grant T. Kirker; Ming-liang Jiang; Yu-zhang Wu

    2016-01-01

    Surface coatings of melamine-modified urea-formaldehyde resins (MUFs) containing ammonium polyphosphate (APP) have been shown to significantly improve the fire retardancy of wood by prolonging the ignition time and reducing the heat release rate, total heat released, and mass loss rate. Dual protection of wood against both decay and fire has been proposed for remedial...

  5. Melamine trisulfonic acid as a highly efficient catalyst for the synthe-sis of 14-aryl-14H-dibenzo[a,j]xanthenes under solvent-free conditions

    Directory of Open Access Journals (Sweden)

    Abdolkarim Zare

    2014-02-01

    Full Text Available Melamine trisulfonic acid (MTSA is utilized as a highly efficient catalyst for the solvent-free condensation of 2-naphthol with arylaldehydes under conventional thermal or microwave irradiation to give 14-aryl-14H-dibenzo[a,j]xanthenes in high to excellent yields and in short reaction times.

  6. [Preparation of hydrophilic interaction monolithic column and its application in the analysis of melamine in dairy products using pressurized capillary electrochromatography].

    Science.gov (United States)

    Li, Xinyan; Wang, Yan; Gu, Xue; Chen, Yan; Yan, Chao

    2010-03-01

    The hydrophilic monolithic column was prepared in 100 microm i. d. capillary in situ using ethylene dimethacrylate as crosslinker, butyl methacrylate and 3-[dimethyl-[2-(2-methyl-prop-2-enoyloxy) ethyl] azaniumyl] propane-1-sulfonate as monomers. In the study, the hydrophilic interaction behavior of the monolithic column was demonstrated. The application of the column in pressurized capillary electrochromatography (pCEC) for the separation of melamine with ultraviolet detection has been studied. The effects of the composition of mobile phase, pH value, the concentration of the buffer, the flow rate of pump and voltage were investigated. The optimum separation for melamine was achieved with the mobile phase of 10 mmol/L phosphate buffer (pH 3.0) and acetonitrile (20: 80, v/v), voltage at 3 kV and UV detection at 215 nm. The limits of detection (LODs) (S/N = 3) for melamine standard was 0.05 mg/L. The method is simple, accurate and works well without using the ion-pairing agent. The powdered milk and liquid milk were analyzed quantitatively by pCEC using the hydrophilic interaction monolithic column. It is shown that this method is promising in the routine analysis of melamine in dairy products.

  7. Minimally invasive percutaneous nephrolithotomy in preschool age children with kidney calculi (including stones induced by melamine-contaminated milk powder).

    Science.gov (United States)

    Yan, Xiang; Al-Hayek, Samih; Gan, Weidong; Zhu, Wei; Li, Xiaogong; Guo, Hongqian

    2012-10-01

    This study was undertaken to assess the safety and efficacy of minimally invasive percutaneous nephrolithotomy (mini-PCNL) using ureteroscope and pneumatic intracorporeal lithotripsy in preschool age children with kidney calculi. We studied 27 renal units in 20 patients of preschool age (≤ 6 years) who underwent mini-PCNL at our institute. The mean age was 42.6 months (range 14-68 months). The average stone burden was 1.85 cm (range 0.9-2.8 cm). Eight patients aged 14 to 58 months had been exposed to melamine-tainted powdered formula. The mini-PCNL was performed with an X-ray-guided peripheral puncture. Minimal tract dilatation was undertaken to fit a 14-16 Fr peel-away sheath. Ureteroscope and pneumatic intracorporeal lithotripsy were used to fragment the stones. Complete clearance was achieved in 23 renal units (85.2 %) with mini-PCNL monotherapy. This has increased to 92.6 % after adjunctive ESWL. The average fall in hemoglobin was 1.28 g/dL. None of the patients required blood transfusion. The median length of hospital stay was 8.2 days. Patients were followed up every 6 months for 2 years. There has been only one recurrence of stone and no long-term complications. Mini-PCNL is a effective treatment for pediatric kidney stones refractory to extracorporeal shock wave lithotripsy, including stones induced by melamine-contaminated milk powder. The "mini-PCNL" technique, which uses ureteroscope and pneumatic intracorporeal lithotripsy, is a safe and feasible modality for treating renal calculi in preschool age children.

  8. Synthesis of g-C{sub 3}N{sub 4} with heating acetic acid treated melamine and its photocatalytic activity for hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ming; Yan, Jun-Min; Zhang, Xue-wei; Zhao, Ming, E-mail: zhaoming@jlu.edu.cn

    2015-11-01

    Highlights: • We have successfully synthesized small size and porous g-C3N4 with no template by heating acetic acid treated melamine. • This new g-C3N4 samples show high photocatalytic activity and stability for hydrogen generation under visible-light irradiation. - Abstract: The g-C{sub 3}N{sub 4} is synthesized by directly heating the acetic acid treatment melamine. A combination of XRD, SEM, TEM, PL and UV–vis are utilized to characterize the composition, morphology and optical properties of g-C{sub 3}N{sub 4}. This method synthesized g-C{sub 3}N{sub 4} shows smaller particles and some holes which high up the photocatalytic activity compared with the bulk g-C{sub 3}N{sub 4}.

  9. Determination of melamine in milk-based products and other food and beverage products by ion-pair liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, Maria; Sancho, Juan V. [Research Institute for Pesticides and Water, University Jaume I, E-12071, Castellon (Spain); Hernandez, Felix, E-mail: felix.hernandez@qfa.uji.es [Research Institute for Pesticides and Water, University Jaume I, E-12071, Castellon (Spain)

    2009-09-01

    This paper describes a fast method for the sensitive and selective determination of melamine in a wide range of food matrices, including several milk-based products. The method involves an extraction with aqueous 1% trichloroacetic acid before the injection of the 10-fold diluted extract into the liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) system, using labelled melamine as the internal standard. As melamine is present in aqueous media in the cationic form, the chromatographic separation in reversed-phase LC requires the use of anionic ion-pair reagents, such as tridecafluoroheptanoic acid (THFA). This allows a satisfactory chromatographic retention and peak shape in all the types of food samples investigated. The method has been validated in six food matrices (biscuit, dry pasta and four milk-based products) by means of recovery experiments in samples spiked at 1 and 5 mg kg{sup -1}. Average recoveries (n = 5) ranged from 77% to 100%, with excellent precision (RSDs lower than 5%) and limits of detection between 0.01 and 0.1 mg kg{sup -1}. In addition, accuracy and robustness of the method was proven in different soya-based matrices by means of quality control (QC) sample analysis. QC recoveries, at 1 and 2.5 mg kg{sup -1}, were satisfactory, ranging from 79% to 110%. The method developed in this work has been applied to the determination of melamine in different types of food samples. All detections were confirmed by acquiring two MS/MS transitions (127 > 85 for quantification; 127 > 68 for confirmation) and comparing their ion intensity ratio with that of reference standards. Accuracy of the method was also assessed by applying it to a milk-based product and a baking mix material as part of an EU proficiency test, in which highly satisfactory results were obtained.

  10. Synthesis of g-C3N4 with heating acetic acid treated melamine and its photocatalytic activity for hydrogen evolution

    Science.gov (United States)

    Wu, Ming; Yan, Jun-Min; Zhang, Xue-wei; Zhao, Ming

    2015-11-01

    The g-C3N4 is synthesized by directly heating the acetic acid treatment melamine. A combination of XRD, SEM, TEM, PL and UV-vis are utilized to characterize the composition, morphology and optical properties of g-C3N4. This method synthesized g-C3N4 shows smaller particles and some holes which high up the photocatalytic activity compared with the bulk g-C3N4.

  11. Fabrication of micro-dot arrays and micro-walls of acrylic acid/melamine resin on aluminum by AFM probe processing and electrophoretic coating

    Energy Technology Data Exchange (ETDEWEB)

    Kurokawa, S.; Kikuchi, T.; Sakairi, M. [Graduate School of Engineering, Hokkaido University, N-13, W-8, Kita-Ku, Sapporo 060-8628 (Japan); Takahashi, H. [Graduate School of Engineering, Hokkaido University, N-13, W-8, Kita-Ku, Sapporo 060-8628 (Japan)], E-mail: takahasi@elechem1-mc.eng.hokudai.ac.jp

    2008-11-30

    Micro-dot arrays and micro-walls of acrylic acid/melamine resin were fabricated on aluminum by anodizing, atomic force microscope (AFM) probe processing, and electrophoretic deposition. Barrier type anodic oxide films of 15 nm thickness were formed on aluminum and then the specimen was scratched with an AFM probe in a solution containing acrylic acid/melamine resin nano-particles to remove the anodic oxide film locally. After scratching, the specimen was anodically polarized to deposit acrylic acid/melamine resin electrophoretically at the film-removed area. The resin deposited on the specimen was finally cured by heating. It was found that scratching with the AFM probe on open circuit leads to the contamination of the probe with resin, due to positive shifts in the potential during scratching. Scratching of the specimen under potentiostatic conditions at -1.0 V, however, resulted in successful resin deposition at the film-removed area without probe contamination. The rate of resin deposition increased as the specimen potential becomes more positive during electrophoretic deposition. Arrays of resin dots with a few to several tens {mu}m diameter and 100-1000 nm height, and resin walls with 100-1000 nm height and 1 {mu}m width were obtained on specimens by successive anodizing, probe processing, and electrophoretic deposition.

  12. The Influence of pH on the Melamine-Dimethylurea-Formaldehyde Co-Condensations: A Quantitative 13C-NMR Study

    Directory of Open Access Journals (Sweden)

    Ming Cao

    2017-03-01

    Full Text Available 1,3-dimethylurea (DMU was used to mimic urea and to model melamine-urea-formaldehyde (MUF co-condensation reactions. The products of 1,3-dimethylurea-formaldehyde (DMUF, melamine-formaldehyde (MF, and melamine-1,3-dimethylurea-formaldehyde (MDMUF reactions under alkaline and weak acidic conditions were compared by performing quantitative carbon-13 nuclear magnetic resonance (13C-NMR analysis. The effect of pH on the co-condensation reactions was clarified. With the presence of the methyl groups in DMU, the appearance or absence of the featured signal at 54–55 ppm can be used to identify the co-condensed methylene linkage –N(–CH3 –CH2–NH–. Under alkaline condition, MDMUF reactions produced primarily MF polymers and the featured signal at 54–55 ppm was absent. Even though the co-condensations concurrently occurred, undistinguishable and very minor condensed structures with ether linkage were formed. Differently, under weak acidic condition, the relative content of co-condensed methylene carbons accounts for over 40%, indicating the MDMUF co-condensation reactions were much more competitive than the self-condensations. The formation of reactive carbocation intermediate was proposed to rationalize the results.

  13. Sample Preparation of Eggs from Laying Hens Using QuEChERS Dispersive Extraction for the Simultaneous Determination of Melamine and Cyromazine Residues by HPLC-DAD

    Directory of Open Access Journals (Sweden)

    Niki Tsartsali

    2015-01-01

    Full Text Available A quick, easy, cheap, effective, rugged, and safe (QuEChERS dispersive extraction method is proposed herein for the isolation and cleanup of melamine and cyromazine from chicken egg yolk. Analytes are determined by high-performance liquid chromatography using photodiode array detector after separation on a LiChroCART® (250 × 4 mm–-LiChrospher® RP-8e, 5 µm analytical column using a mobile phase of 0.1% trifluoracetic acid and methanol (80:20 v/v delivered isocratically at a flow rate of 1 mL/minute. Extraction of isolated compounds was achieved by methanol and acetonitrile mixture (1:1 v/v. Recovery rates ranged between 74.5% and 115.8%. The method was validated in terms of 657/2002/EC decision. The within-laboratory reproducibility, expressed as a relative standard deviation, was <11%. Decision limits (CCalfa were 2.56 mg/kg for melamine and 0.22 mg/kg -1 for cyromazine, and the corresponding results for detection capability (CCbeta were 2.8 mg/kg for melamine and 0.24 mg/kg for cyromazine. Ruggedness was estimated according to the Youden approach studying egg yolk mass, sorbent mass, centrifugation time, organic solvents volume, evaporation temperature, and vortex time.

  14. Melamine detection by mid- and near-infrared (MIR/NIR) spectroscopy: a quick and sensitive method for dairy products analysis including liquid milk, infant formula, and milk powder.

    Science.gov (United States)

    Balabin, Roman M; Smirnov, Sergey V

    2011-07-15

    Melamine (2,4,6-triamino-1,3,5-triazine) is a nitrogen-rich chemical implicated in the pet and human food recalls and in the global food safety scares involving milk products. Due to the serious health concerns associated with melamine consumption and the extensive scope of affected products, rapid and sensitive methods to detect melamine's presence are essential. We propose the use of spectroscopy data-produced by near-infrared (near-IR/NIR) and mid-infrared (mid-IR/MIR) spectroscopies, in particular-for melamine detection in complex dairy matrixes. None of the up-to-date reported IR-based methods for melamine detection has unambiguously shown its wide applicability to different dairy products as well as limit of detection (LOD) below 1 ppm on independent sample set. It was found that infrared spectroscopy is an effective tool to detect melamine in dairy products, such as infant formula, milk powder, or liquid milk. ALOD below 1 ppm (0.76±0.11 ppm) can be reached if a correct spectrum preprocessing (pretreatment) technique and a correct multivariate (MDA) algorithm-partial least squares regression (PLS), polynomial PLS (Poly-PLS), artificial neural network (ANN), support vector regression (SVR), or least squares support vector machine (LS-SVM)-are used for spectrum analysis. The relationship between MIR/NIR spectrum of milk products and melamine content is nonlinear. Thus, nonlinear regression methods are needed to correctly predict the triazine-derivative content of milk products. It can be concluded that mid- and near-infrared spectroscopy can be regarded as a quick, sensitive, robust, and low-cost method for liquid milk, infant formula, and milk powder analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Study of Non-Isothermal Decomposition and Kinetic Analysis of 2,4-Dihydroxybenzoic Acid- Melamine-Formaldehyde Copolymer

    Directory of Open Access Journals (Sweden)

    S. S. Butoliya

    2010-01-01

    Full Text Available A copolymer (2,4-DHBAMF synthesized by the condensation of 2,4-dihydroxybenzoic acid and melamine with formaldehyde in the presence of acid catalyst using varied molar proportions of the reactants. A composition of the copolymer has been determined by elemental analysis. The number average molecular weight has been determined by conductometric titration in non-aqueous medium. The copolymer has been characterized by UV-Visible, IR and 1H NMR spectral analysis. Thermogravimetric analysis was carried out to study the decomposition and various kinetic parameters. Freeman Carroll and Sharp Wentworth methods have been applied for the calculation of kinetic parameters while the data from Freeman Carroll method have been used to determine various thermodynamic parameters such as order of reaction, energy of activation, frequency factor, entropy change, free energy change and apparent entropy change. The results indicate that given copolymer have potential as matrix resin for long term applications at temperature up to 350 °C.

  16. Catalyst-free synthesis of nitrogen-doped graphene via thermal annealing graphite oxide with melamine and its excellent electrocatalysis.

    Science.gov (United States)

    Sheng, Zhen-Huan; Shao, Lin; Chen, Jing-Jing; Bao, Wen-Jing; Wang, Feng-Bin; Xia, Xing-Hua

    2011-06-28

    The electronic and chemical properties of graphene can be modulated by chemical doping foreign atoms and functional moieties. The general approach to the synthesis of nitrogen-doped graphene (NG), such as chemical vapor deposition (CVD) performed in gas phases, requires transitional metal catalysts which could contaminate the resultant products and thus affect their properties. In this paper, we propose a facile, catalyst-free thermal annealing approach for large-scale synthesis of NG using low-cost industrial material melamine as the nitrogen source. This approach can completely avoid the contamination of transition metal catalysts, and thus the intrinsic catalytic performance of pure NGs can be investigated. Detailed X-ray photoelectron spectrum analysis of the resultant products shows that the atomic percentage of nitrogen in doped graphene samples can be adjusted up to 10.1%. Such a high doping level has not been reported previously. High-resolution N1s spectra reveal that the as-made NG mainly contains pyridine-like nitrogen atoms. Electrochemical characterizations clearly demonstrate excellent electrocatalytic activity of NG toward the oxygen reduction reaction (ORR) in alkaline electrolytes, which is independent of nitrogen doping level. The present catalyst-free approach opens up the possibility for the synthesis of NG in gram-scale for electronic devices and cathodic materials for fuel cells and biosensors.

  17. Flame-Retardant and Thermal Degradation Mechanism of Caged Phosphate Charring Agent with Melamine Pyrophosphate for Polypropylene

    Directory of Open Access Journals (Sweden)

    Xuejun Lai

    2015-01-01

    Full Text Available An efficient caged phosphate charring agent named PEPA was synthesized and combined with melamine pyrophosphate (MPP to flame-retard polypropylene (PP. The effects of MPP/PEPA on the flame retardancy and thermal degradation of PP were investigated by limiting oxygen index (LOI, vertical burning test (UL-94, cone calorimetric test (CCT, and thermogravimetric analysis (TGA. It was found that PEPA showed an outstanding synergistic effect with MPP in flame retardant PP. When the content of PEPA was 13.3 wt% and MPP was 6.7 wt%, the LOI value of the flame retardant PP was 33.0% and the UL-94 test was classed as a V-0 rating. Meanwhile, the peak heat release rate (PHRR, average heat release rate (AV-HRR, and average mass loss rate (AV-MLR of the mixture were significantly reduced. The flame-retardant and thermal degradation mechanism of MPP/PEPA was investigated by TGA, Fourier transform infrared spectroscopy (FTIR, TG-FTIR, and scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDXS. It revealed that MPP/PEPA could generate the triazine oligomer and phosphorus-containing compound radicals which changed the thermal degradation behavior of PP. Meanwhile, a compact and thermostable intumescent char was formed and covered on the matrix surface to prevent PP from degrading and burning.

  18. Sodium hyaluronate-functionalized urea-formaldehyde monolithic column for hydrophilic in-tube solid-phase microextraction of melamine.

    Science.gov (United States)

    Wang, Jiabin; Jiang, Nan; Cai, Zhengmiao; Li, Wenbang; Li, Jianhua; Lin, Xucong; Xie, Zenghong; You, Lijun; Zhang, Qiqing

    2017-09-15

    A novel sodium hyaluronate-functionalized urea-formaldehyde (UF) monolithic column has been developed by in-situ polycondensation of urea, formaldehyde and sodium hyaluronate (HA). HA plays both the roles of crosslinking and hydrophilic functionalization. The preparation factors including different molecular weights of HA and different amounts of HA were optimized, and then a uniform monolith with satisfactory permeability and hydrophilic binding capacity was obtained. Due to the excellent hydrophilicity of HA, HA-functionalized UF monolith showed higher hydrophilic extraction efficiency than UF monolith, and was applied for hydrophilic in-tube solid-phase microextraction (SPME) of melamine (MEL). Several factors for hydrophilic in-tube SPME, such as ACN percentage in the sampling solution, salt concentration and pH value of the sampling solution, elution volume, sampling and elution flow rate, were investigated with respect to the extraction efficiency of MEL. Under the optimized SPME conditions, the limit of detection (LOD) of MEL was found to be 0.2ng/mL in the milk formula samples, the recoveries of MEL spiked in milk formula samples ranged from 87.3% to 96.7% with relative standard deviations (RSDs) less than 5.1%. Owing to the excellent hydrophilic extraction ability, the novel HA-functionalized UF monolith could provide a promising tool for the sensitive analysis of polar analytes in complicated samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Surface tectonics of nanoporous networks of melamine-capped molecular building blocks formed through interface Schiff-base reactions.

    Science.gov (United States)

    Liu, Xuan-He; Wang, Dong; Wan, Li-Jun

    2013-10-01

    Control over the assembly of molecules on a surface is of great importance for the fabrication of molecule-based miniature devices. Melamine (MA) and molecules with terminal MA units are promising candidates for supramolecular interfacial packing patterning, owing to their multiple hydrogen-bonding sites. Herein, we report the formation of self-assembled structures of MA-capped molecules through a simple on-surface synthetic route. MA terminal groups were successfully fabricated onto rigid molecular cores with 2-fold and 3-fold symmetry through interfacial Schiff-base reactions between MA and aldehyde groups. Sub-molecular scanning tunneling microscopy (STM) imaging of the resultant adlayer revealed the formation of nanoporous networks. Detailed structural analysis indicated that strong hydrogen-bonding interactions between the MA groups persistently drove the formation of nanoporous networks. Herein, we demonstrate that functional groups with strong hydrogen-bond-formation ability are promising building blocks for the guided assembly of nanoporous networks and other hierarchical 2D assemblies. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Simple synthesis of porous melamine-formaldehyde resins by low temperature solvothermal method and its CO2 adsorption properties

    Directory of Open Access Journals (Sweden)

    F. Yin

    2017-11-01

    Full Text Available A simple and environmentally-friendly approach for the preparation of porous melamine-formaldehyde resins (PMFRs was developed by using low-boiling-point solvents, such as water, as pore-forming agent. With using dimethyl sulfoxide (DMSO and low-boiling solvents cosolvent method, PMFRs with a high specific surface area and well-defined pore structure can be synthesized at a low reaction temperature of 140 °C for a short reaction duration in 20 hours, which can replace the conventional methods that use dimethyl sulfoxide (DMSO as reaction medium and require 3 days at 170 °C to achieve similar surface area. When loaded with polyethylenimine (PEI, the PMFR-PEI-30% showed good CO2 adsorption performance with a capacity of up to 2.89 mmol/g at 30 °C. These results bring new perspectives for the development of lowcost and environmentally-friendly synthetic methods for porous materials, which can boost their widespread applications.

  1. Effects of cryogenic temperature on the mechanical and failure characteristics of melamine-urea-formaldehyde adhesive plywood

    Science.gov (United States)

    Kim, Jeong-Hyeon; Choi, Sung-Woong; Park, Doo-Hwan; Park, Seong-Bo; Kim, Seul-Kee; Park, Kwang-Jun; Lee, Jae-Myung

    2018-04-01

    The present study investigates the applicability of melamine-urea-formaldehyde (MUF) resin plywood in cryogenic applications, including liquefied natural gas (LNG) carrier insulation systems. Phenolic-formaldehyde (PF) resin plywood has been extensively used as a structural material in industrial applications. However, many shortcomings of PF resin plywood have been reported, and replacement of PF resin plywood with a new material is necessary to resolve these problems. MUF resin plywood has the advantages of short fabrication time, low veneer cost, and economic feasibility compared to PF resin plywood. However, the mechanical and failure characteristics of MUF resin plywood have not yet been investigated at low temperature ranges. For this reason, adapting MUF resin plywood for cryogenic applications has been difficult, despite the many strong points of the material in engineering aspects. In this study, the effects of cryogenic temperature and thermal treatment on the mechanical characteristics of MUF resin plywood are investigated. The performance of MUF resin plywood is compared with that of PF resin plywood to verify the applicability of the material for use as a structural material in LNG insulation systems. The results demonstrate that MUF resin plywood has mechanical properties comparable with those of PF resin plywood, even at cryogenic conditions.

  2. Development of an immunochromatographic strip test for rapid detection of melamine in raw milk, milk products and animal feed.

    Science.gov (United States)

    Li, Xiangmei; Luo, Pengjie; Tang, Shusheng; Beier, Ross C; Wu, Xiaoping; Yang, Lili; Li, Yanwei; Xiao, Xilong

    2011-06-08

    A simple, rapid and sensitive immunogold chromatographic strip test based on a monoclonal antibody was developed for the detection of melamine (MEL) residues in raw milk, milk products and animal feed. The limit of detection was estimated to be 0.05 μg/mL in raw milk, since the detection test line on the strip test completely disappeared at this concentration. The limit of detection was 2 μg/mL (or 2 μg/g) for milk drinks, yogurt, condensed milk, cheese, and animal feed and 1 μg/g for milk powder. Sample pretreatment was simple and rapid, and the results can be obtained within 3-10 min. A parallel analysis of MEL in 52 blind raw milk samples conducted by gas chromatography-mass spectrometry showed comparable results to those obtained from the strip test. The results demonstrate that the developed method is suitable for the onsite determination of MEL residues in a large number of samples.

  3. A Fast and Cost-Effective Detection of Melamine by Surface Enhanced Raman Spectroscopy Using a Novel Hydrogen Bonding-Assisted Supramolecular Matrix and Gold-Coated Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jing Neng

    2017-05-01

    Full Text Available A fast and cost-effective melamine detection approach has been developed based on surface enhanced Raman spectroscopy (SERS using a novel hydrogen bonding-assisted supramolecular matrix. The detection utilizes Fe3O4/Au magnetic nanoparticles coated with 5-aminoorotic acid (AOA as a SERS active substrate (Fe3O4/Au–AOA, and Rhodamine B (RhB conjugated AOA as a Raman reporter (AOA–RhB. Upon mixing the reagents with melamine, a supramolecular complex [Fe3O4/Au–AOA•••melamine•••AOA–RhB] was formed due to the strong multiple hydrogen bonding interactions between AOA and melamine. The complex was separated and concentrated to a pellet by an external magnet and used as a supramolecular matrix for the melamine detection. Laser excitation of the complex pellet produced a strong SERS signal diagnostic for RhB. The logarithmic intensity of the characteristic RhB peaks was found to be proportional to the concentration of melamine with a limit of detection of 2.5 µg/mL and a detection linearity range of 2.5~15.0 µg/mL in milk. As Fe3O4 nanoparticles and AOA are thousands of times less expensive than the monoclonal antibody used in a traditional sandwich immunoassay, the current assay drastically cut down the cost of melamine detection. The current approach affords promise as a biosensor platform that cuts down sample pre-treatment steps and measurement expense.

  4. One-pot synthesis of copper-doped graphitic carbon nitride nanosheet by heating Cu–melamine supramolecular network and its enhanced visible-light-driven photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Junkuo, E-mail: jkgao@zstu.edu.cn [The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab for Textile Fiber Materials and Processing Technology (Zhejiang), College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Wang, Jiangpeng [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Qian, Xuefeng; Dong, Yingying [The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab for Textile Fiber Materials and Processing Technology (Zhejiang), College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Xu, Hui; Song, Ruijing [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Yan, Chenfeng [The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab for Textile Fiber Materials and Processing Technology (Zhejiang), College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Zhu, Hangcheng [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Zhong, Qiwei [The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab for Textile Fiber Materials and Processing Technology (Zhejiang), College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018 (China); and others

    2015-08-15

    Here we report a novel synthetic pathway for preparation of Cu-doped g-C{sub 3}N{sub 4} (Cu-g-C{sub 3}N{sub 4}) with nanosheet morphology by using a two dimensional Cu–melamine supramolecular network as both sacrificial template and precursor. The specific surface area of Cu-g-C{sub 3}N{sub 4} is 40.86 m{sup 2} g{sup −1}, which is more than 7 times larger than that of pure g-C{sub 3}N{sub 4}. Cu-g-C{sub 3}N{sub 4} showed strong optical absorption in the visible-light region and expanded the absorption to the near-infrared region. The uniform nanosheet morphology, higher surface area and strong visible-light absorption have enabled Cu-g-C{sub 3}N{sub 4} exhibiting enhanced visible light photocatalytic activity for the photo-degradation of methylene blue (MB). The results indicate that metal–melamine supramolecular network can be promising precursors for the one step preparation of efficient metal-doped g-C{sub 3}N{sub 4} photocatalysts. - Graphical abstract: Cu-doped g-C{sub 3}N{sub 4} (Cu-g-C{sub 3}N{sub 4}) with nanosheet morphology was fabricated via a simple one step preparation by using a two dimensional Cu–melamine supra-molecular network as both sacrificial template and precursor. - Highlights: • Cu-doped g-C{sub 3}N{sub 4} (Cu-g-C{sub 3}N{sub 4}) with nanosheet morphology was prepared. • Cu-g-C{sub 3}N{sub 4} showed strong optical absorption in the visible-light region. • Cu-g-C{sub 3}N{sub 4} exhibits enhanced visible light photocatalytic activity.

  5. Determination of melamine in soil samples using surfactant-enhanced hollow fiber liquid phase microextraction followed by HPLC–UV using experimental design

    Directory of Open Access Journals (Sweden)

    Ali Sarafraz Yazdi

    2015-11-01

    Full Text Available Surfactant-enhanced hollow fiber liquid phase (SE-HF-LPME microextraction was applied for the extraction of melamine in conjunction with high performance liquid chromatography with UV detection (HPLC–UV. Sodium dodecyl sulfate (SDS was added firstly to the sample solution at pH 1.9 to form hydrophobic ion-pair with protonated melamine. Then the protonated melamine–dodecyl sulfate ion-pair (Mel–DS was extracted from aqueous phase into organic phase immobilized in the pores and lumen of the hollow fiber. After extraction, the analyte-enriched 1-octanol was withdrawn into the syringe and injected into the HPLC. Preliminary, one variable at a time method was applied to select the type of extraction solvent. Then, in screening step, the other variables that may affect the extraction efficiency of the analyte were studied using a fractional factorial design. In the next step, a central composite design was applied for optimization of the significant factors having positive effects on extraction efficiency. The optimum operational conditions included: sample volume, 5 mL; surfactant concentration, 1.5 mM; pH 1.9; stirring rate, 1500 rpm and extraction time, 60 min. Using the optimum conditions, the method was analytically evaluated. The detection limit, relative standard deviation and linear range were 0.005 μg mL−1, 4.0% (3 μg mL−1, n = 5 and 0.01–8 μg mL−1, respectively. The performance of the procedure in extraction of melamine from the soil samples was good according to its relative recoveries in different spiking levels (95–109%.

  6. Improvement in photocatalytic H{sub 2} evolution over g-C{sub 3}N{sub 4} prepared from protonated melamine

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yujiao; Wang, Zhiqiang; Feng, Jianyong; Yan, Shicheng [National Laboratory of Solid State Microstructures, College of Engineering and Applied Science, Ecomaterials and Renewable Energy Research Center (ERERC), Nanjing University, No. 22 Hankou Road, Nanjing 210093 (China); Zhang, Haitao [School of Chemistry and Chemical Engineering, University of Jinan (China); Li, Zhaosheng, E-mail: zsli@nju.edu.cn [National Laboratory of Solid State Microstructures, College of Engineering and Applied Science, Ecomaterials and Renewable Energy Research Center (ERERC), Nanjing University, No. 22 Hankou Road, Nanjing 210093 (China); Zou, Zhigang [National Laboratory of Solid State Microstructures, College of Engineering and Applied Science, Ecomaterials and Renewable Energy Research Center (ERERC), Nanjing University, No. 22 Hankou Road, Nanjing 210093 (China)

    2014-03-01

    Highlights: • Porous g-C{sub 3}N{sub 4} samples (pm-g-C{sub 3}N{sub 4}) were prepared by sintering protonated melamine. • Condensation degree of pm-g-C{sub 3}N{sub 4} turns larger with increasing calcination temperature. • The protonation may reduce recombination of photogenerated carriers in pm-g-C{sub 3}N{sub 4}. • The highest hydrogen evolution rate of 417 μmol h{sup −1} g{sup −1} was achieved over pm-g-C{sub 3}N{sub 4}. - Abstract: Porous g-C{sub 3}N{sub 4} (pm-g-C{sub 3}N{sub 4}) samples were prepared by sintering protonated melamine. Photocatalytic activities for H{sub 2} production over the g-C{sub 3}N{sub 4} samples were evaluated under visible-light irradiation. Specific surface areas and condensation degree of the g-C{sub 3}N{sub 4} samples prepared from protonated melamine turn larger as the calcination temperatures increase (400 °C, 450 °C, 500 °C, 550 °C, and 580 °C for 1 h). Also, their bandgaps are narrowed and PL peak red shifts, and thus their photocatalytic activities are enhanced. Compared with the reference g-C{sub 3}N{sub 4} samples synthesized by sintering melamine without any protonation (m-g-C{sub 3}N{sub 4}), the pm-g-C{sub 3}N{sub 4} samples exhibit better photocatalytic performances, owing to larger specific surface area, less recombination of photogenerated carriers and higher degree of condensation. By optimizing the preparation parameters and the amount of Pt cocatalyst, the highest hydrogen evolution rate of 417 μmol h{sup −1} g{sup −1} was achieved over the pm-g-C{sub 3}N{sub 4} samples synthesized at 550 °C for 2 h, when irradiated by 300-W Xe lamp with a cutoff filter (λ ≥ 420 nm)

  7. Investigation on the effect of mixed rapeseed stalk residues with wood particles, and mixing of melamine and urea formaldehyde resin on properties of manufactured particleboard

    Directory of Open Access Journals (Sweden)

    Behzad Kord

    2016-09-01

    Full Text Available In this study, the possibility of using the rapeseed stalk mixed with industrial wood particles for manufacturing particleboard with target density of 0.7 gr/cm3 was considered. Variable factors such as mixing ratios of rapeseed stalk with industrial wood particles at five mixing levels of (0-100, 25-75, 50-50, 75-25 and 100-0 percent, mixing ratios of melamine resin with urea formaldehyde at three levels of 0-100, 15-85 and 30-70 percent, and kind of board at two levels of homogenate and layer were considered. 10 percent resin based on oven dried weight of particles, 2 percent catalyzer based on oven dried weight of resin, press temperature and time with 170 OC and 7 minute, press pressure and rate with 30 Kg/cm3 and 4.5 mm/min were fixed. Then, the boards were manufactured and the physical and mechanical properties including modulus of rupture, modulus of elasticity, internal bonding, water absorption and thickness swelling were measured according to EN standard. Results indicated that the modulus of rupture, modulus of elasticity, water absorption and thickness swelling of boards increased with increase rapeseed stalk loading; however, the internal bonding decreased. Also, the use of melamine urea formaldehyde resin caused to improve the mechanical strength and dimensional stability in the samples.

  8. The Clinical Profile and Prognosis of Chinese Children with Melamine-Induced Kidney Disease: A Systematic Review and Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Pei-Xin Wang

    2013-01-01

    Full Text Available Introduction. Studies have reported inconsistent results regarding clinical feature and the prognosis status of the affected children in China melamine-contamination event. We summarized available literatures by performing a review and meta-analysis. Methods. Statistical pooling was performed using random-effects model; the sources of heterogeneity were explored through subgroup analyses. Results. Twenty-six studies involving 2164 patients with kidney abnormalities were identified; 94.4% of the patients had urinary calculi and 95.8% of the calculi were <10 mm in diameter. Of 2040 patients with known types of treatment, 5.6% underwent surgical treatment. The pooled recovery rates at 1, 3, 6, and 12 months after diagnosis or treatment initiation were 67.1%, 76.3%, 85.4%, and 92.3%, respectively; these pooled rates did not differ between the study subgroups stratified by mean age at diagnosis, mean duration of melamine exposure, types of patients (inpatient/outpatient, and treatment types (specific/nonspecific, except that the 1-month recovery rate for studies involving a specific treatment (71.9% was higher than that for studies involving non-specific treatment (46.2%. Conclusion. The majority of patients had small calculi and could recover without surgical treatment. Kidney abnormalities remained in about 8% of the patients at 12-month followup, indicating a need for longer-term followup.

  9. Integrated effect of supramolecular self-assembled sandwich-like melamine cyanurate/MoS{sub 2} hybrid sheets on reducing fire hazards of polyamide 6 composites

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiaming [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Wang, Xin, E-mail: wxcmx@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Cai, Wei; Hong, Ningning [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Liew, Kim Meow [Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Department of Architectural and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2016-12-15

    A novel strategy of using supramolecular self-assembly for preparing sandwich-like melamine cyanurate/MoS{sub 2} sheets as the hybrid flame retardants for polyamide 6 (PA6) is reported for the first time. The introduction of MoS{sub 2} sheets function not only as a template to induce the formation of two-dimensional melamine cyanurate capping layers but also as a synergist to generate integrated flame-retarding effect of hybrid sheets, as well as a high-performance smoke suppressor to reduce fire hazards of PA6 materials. Once incorporating this well-designed structures (4 wt%) into PA6 matrix, there resulted in a remarkable drop (40%) in the peak heat release rate and a 25% reduction in total heat release. Moreover, the smoke production and pyrolysis gaseous products were efficiently suppressed by the addition of sandwich-like hybrid sheets. The integrated functions consisting of inherent flame retarding effect, physical barrier performance and catalytic activity are believed to the crucial guarantee for the reduced fire hazards of PA6 nanocomposites. Furthermore, this novel strategy with facile and scalable features may provide reference for developing various kinds of MoS{sub 2} based hybrid sheets for diverse applications.

  10. Gas chromatographic determination of N-nitrosamines, aromatic amines, and melamine in milk and dairy products using an automatic solid-phase extraction system.

    Science.gov (United States)

    Jurado-Sanchez, Beatriz; Ballesteros, Evaristo; Gallego, Mercedes

    2011-07-13

    A reliable analytical method was presented for the simultaneous determination of six N-nitrosamines, nine aromatic amines, and melamine in milk and dairy products using gas chromatography coupled with mass spectrometry. The sample treatment includes the precipitation of proteins with acetonitrile, centrifugation, solvent changeover by evaporation, and continuous solid-phase extraction for cleanup and preconcentration purposes. Samples (5 g) containing 0.15-500 ng of each amine were analyzed, and low detection limits (15-130 ng/kg) were achieved. Recoveries for milk and dairy products samples spiked with 1, 10, and 50 μg/kg ranged from 92% to 101%, with intraday and interday relative standard deviation values below 7.5%. The method was successfully applied to determine amine residues in several milk types (human breast, cow, and goat) and dairy products.

  11. Separation of Cr(III) and Cr(VI) using melamine-formaldehyde resin and determination of both species in water by FAAS

    Energy Technology Data Exchange (ETDEWEB)

    Demirata, B. [Department of Chemistry, Faculty of Science and Letters, Istanbul Technical University (Turkey); Tor, I. [Department of Chemistry, Faculty of Engineering, Istanbul University (Turkey); Filik, H. [Department of Chemistry, Faculty of Engineering, Istanbul University (Turkey); Afsar, H. [Department of Chemistry, Faculty of Science, Yildiz Technical Univ., Istanbul (Turkey)

    1996-11-01

    A method is described for the determination of Cr(VI) and total chromium by FAAS. Cr(VI) is separated from Cr(III) by adsorption on melamine-formaldehyde resin. After elution of Cr(VI) with 0.1 mol/l NaAc solution, it is analysed by FAAS. Total chromium is determined by FAAS after conversion of Cr(III) to Cr(VI) by oxidation with hydrogen peroxide, total Cr(VI) is concentrated as above. If the total concentration of chromium is sufficient, the determination can be directly made by FAAS. Cr(III) can then be calculated by subtracting Cr(VI) from the total Cr. This method was successfully applied to the determination of chromium in lake water. (orig.). With 1 fig., 1 tab.

  12. Synthesis of Cubic Boron Nitride Nanoparticles from Boron Oxide, Melamine and NH3 by Non-Transferred Ar-N2 Thermal Plasma.

    Science.gov (United States)

    Ko, Eun Ha; Kim, Tae-Hee; Choi, Sooseok; Park, Dong-Wha

    2015-11-01

    Cubic boron nitride (c-BN) which is has extremely high hardness and thermal conductivity comparable to the diamond was synthesized in nanoparticle form by using non-transferred thermal plasma. The input power of arc plasma was fixed at 13.5 kW and the operating pressure was also fixed at atmospheric pressure. Boron oxide (B2O3) and melamine (C3H6N6) were used as raw materials for the sources of boron and nitrogen. Ammonia gas (NH3) was additionally injected to plasma jet as reactive gas providing additional nitrogen. Decomposed B2O3 and C3H6N6 enhance reactivity for synthesizing c-BN with exothermic reactions between carbon, hydrogen and oxygen. Products were collected from the inner wall of reactor. In X-ray diffraction and scanning electron microscope measurements, the collected powder was confirmed as c-BN nanoparticles which have crystalline size smaller than 150 nm.

  13. CALCULATIONS OF THE THERMODYNAMIC PARAMETERS OF CLUSTERIZATION OF ALKYL-SUBSTITUTED MELAMINE AT WATER / AIR INTERFACE IN THE FRAMEWORKS OF QUANTUM-CHEMICAL APPROACH

    Directory of Open Access Journals (Sweden)

    E. A. Belyaeva

    2015-06-01

    Full Text Available In this article, within the semi-empirical quantum chemical software package Mopac2012 (PM3 thermodynamic parameters (enthalpy, entropy, Gibbs energy of dimers and tetramers clustering of alkyl-substituted melamine 2CnHn+1 (n = 6 – 16 were calculated. A comparison of the corresponding thermodynamic parameters of these structures with the parameters obtained previously for clusters of similar structure, but built on the basis of the other monomer conformation were carried out. It was shown that structures proposed in this article, in comparison with the previous ones, has a lower Gibbs energy of clustering  that indicates their energetic preference. Therefore, at this stage, we can assume that the proposed monomer structure underlies the monolayers formed on the water surface by this class of substances.

  14. EFFECT OF WOOD SPECIES USED FOR CORE LAYER ON SOME PROPERTIES OF OKUME PLYWOOD PANELS BONDED WITH MELAMINE-UREA FORMALDEHYDE (MUF ADHESIVE

    Directory of Open Access Journals (Sweden)

    Cenk Demirkır

    2005-04-01

    Full Text Available In this study; changes in some properties of the okume plywood panels when used alder and beech veneers in their core layers were investigated. Two types of melamine-urea formaldehyde (MUF resins having different free formaldehyde contents were used for bonding plywood panels manufactured from 2 mm thick veneers at industrial conditions. The formaldehyde emission values of plywood panels bonded with MÜF having higher free formaldehyde content were found to be higher than those of the panels bonded with other resin type. The highest formaldehyde emission value was found for the panels manufactured from okume veneers in all layers while the lowest value was determined from the panels include beech veneers in the core layer. The shear and bending strength values of the panels consisted of beech veneers in the core layer were found to be higher than those of the panels consisted of okume and alder veneers in the core layers.

  15. Activated Carbon by Co-pyrolysis and Steam Activation from Particle Board and Melamine Formaldehyde Resin: Production, Adsorption Properties and Techno Economic Evaluation

    Directory of Open Access Journals (Sweden)

    Kenny Vanreppelen

    2013-03-01

    Full Text Available One of the top strategic objectives and research areas in Europe is recovering wood from processing and end of life products. However, there are still several "contaminated" wood products that are not or only partly reused/recycled. Particle board waste which is contaminated with aminoplasts is one of these products. In addition, a considerable amount of aminoplast waste resinis produced for the production of particle board that cannot be re-used or recycled. The chemical properties of these wastes (high nitrogen content of 5.9 wt% and 54.1 wt% for particle board and melamine formaldehyde respectively make them ideal precursors for the production of nitrogenised activated carbon. The profitability of the produced activated carbon is investigated by calculating the net present value, the minimum selling price and performing a Monte Carlo sensitivity analysis. Encouraging results for a profitable production are obtained even though the current assumptions start from a rather pessimistic scenario.

  16. Sample Preparation of Eggs From Laying Hens Using QuEChERS Dispersive Extraction for the Simultaneous Determination of Melamine and Cyromazine Residues by HPLC-DAD.

    Science.gov (United States)

    Tsartsali, Niki; Samanidou, Victoria F

    2015-01-01

    A quick, easy, cheap, effective, rugged, and safe (QuEChERS) dispersive extraction method is proposed herein for the isolation and cleanup of melamine and cyromazine from chicken egg yolk. Analytes are determined by high-performance liquid chromatography using photodiode array detector after separation on a LiChroCART® (250 × 4 mm)-LiChrospher® RP-8e, 5 μm analytical column using a mobile phase of 0.1% trifluoracetic acid and methanol (80:20 v/v) delivered isocratically at a flow rate of 1 mL/minute. Extraction of isolated compounds was achieved by methanol and acetonitrile mixture (1:1 v/v). Recovery rates ranged between 74.5% and 115.8%. The method was validated in terms of 657/2002/EC decision. The within-laboratory reproducibility, expressed as a relative standard deviation, was evaporation temperature, and vortex time.

  17. Lateral flow test strip based on colloidal selenium immunoassay for rapid detection of melamine in milk, milk powder, and animal feed

    Directory of Open Access Journals (Sweden)

    Wang ZZ

    2014-04-01

    Full Text Available Zhizeng Wang,1 Dejuan Zhi,2 Yang Zhao,1 Hailong Zhang,2 Xin Wang,2 Yi Ru,1 Hongyu Li1,2 1MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, People's Republic of China; 2Institute of Microbiology and Biochemical Pharmacy, School of Pharmaceutics, Lanzhou University, Lanzhou, People's Republic of China Abstract: Although high melamine (MEL intake has been proven to cause serious health problems, MEL is sometimes illegally added to milk products and animal feed, arousing serious food safety concerns. A satisfactory method of detecting MEL in onsite or in-home testing is in urgent need of development. This work aimed to explore a rapid, convenient, and cost-effective method of identifying MEL in milk products or other food by colloidal selenium-based lateral flow immunoassay. Colloidal selenium was synthesized by L-ascorbic acid to reduce seleninic acid at room temperature. After conjugation with a monoclonal antibody anti-MEL, a test strip was successfully prepared. The detection limit of the test strip reached 150 µg/kg, 1,000 µg/kg, and 800 µg/kg in liquid milk, milk powder, and animal feed, respectively. No cross-reactions with homologues cyanuric acid, cyanurodiamide, or ammelide were found. Moreover, the MEL test strip can remain stable after storage for 1 year at room temperature. Our results demonstrate that the colloidal selenium MEL test strip can detect MEL in adulterated milk products or animal feed conveniently, rapidly, and sensitively. In contrast with a colloidal gold MEL test strip, the colloidal selenium MEL test strip was easy to prepare and more cost-efficient. Keywords: melamine, selenium nanoparticles, test strip, milk, animal feed, dairy food

  18. Focused-ion-beam-fabricated Au nanorods coupled with Ag nanoparticles used as surface-enhanced Raman scattering-active substrate for analyzing trace melamine constituents in solution

    International Nuclear Information System (INIS)

    Sivashanmugan, Kundan; Liao, Jiunn-Der; Liu, Bernard Haochih; Yao, Chih-Kai

    2013-01-01

    Graphical abstract: -- Highlights: •Well-ordered Au-nanorod array with a controlled tip ring diameter (Au N Rs d ) is made by focused ion beam. •Au N Rs d coupled with Ag nanoparticles (Ag NPs/Au N Rs d ) is competent to sense target molecules in a solution. •Ag NPs/Au N Rs d SERS active substrate can detect a single molecule of crystal violet. •Ag NPs/Au N Rs d as a SERS-active substrate can distinguish melamine contaminants at low concentrations (e.g., 10 −12 M). -- Abstract: A well-ordered Au-nanorod array with a controlled tip ring diameter (Au N Rs d ) was fabricated using the focused ion beam method. Au N Rs d was then coupled with Ag nanoparticles (Ag NPs) to bridge the gaps among Au nanorods. The effect of surface-enhanced Raman scattering (SERS) on Au N Rs d and Ag NPs/Au N Rs d was particularly verified using crystal violet (CV) as the molecular probe. Raman intensity obtained from a characteristic peak of CV on Au N Rs d was estimated by an enhancement factor of ≈10 7 in magnitude, which increased ≈10 12 in magnitude for that on Ag NPs/Au N Rs d . A highly SERS-active Ag NPs/Au N Rs d was furthermore applied for the detection of melamine (MEL) at very low concentrations. Raman-active peaks of MEL (10 −3 to 10 −12 M) in water or milk solution upon Au N Rs d or Ag NPs/Au N Rs d were well distinguished. The peaks at 680 and 702 cm −1 for MEL molecules were found suitable to be used as the index for sensing low-concentration MEL in a varied solution, while that at 1051 cm −1 was practical to interpret MEL molecules in water or milk solution bonded with Au (i.e., Au N Rs d ) or Ag (i.e., Ag NPs/Au N Rs d ) surface. At the interface of Ag NPs/Au N Rs d and MEL molecules in milk solution, a laser-induced electromagnetic field or hotspot effect was produced and competent to sense low-concentration MEL molecules interacting with Ag and Au surfaces. Accordingly, Ag NPs/Au N Rs d is very promising to be used as a fast and sensitive tool for

  19. A general methodology for inverse estimation of the elastic and anelastic properties of anisotropic open-cell porous materials—with application to a melamine foam

    Energy Technology Data Exchange (ETDEWEB)

    Cuenca, Jacques, E-mail: jcuenca@kth.se; Van der Kelen, Christophe; Göransson, Peter [Marcus Wallenberg Laboratory for Sound and Vibration Research, Royal Institute of Technology (KTH), Teknikringen 8, SE-10044 Stockholm (Sweden)

    2014-02-28

    This paper proposes an inverse estimation method for the characterisation of the elastic and anelastic properties of the frame of anisotropic open-cell foams used for sound absorption. A model of viscoelasticity based on a fractional differential constitutive equation is used, leading to an augmented Hooke's law in the frequency domain, where the elastic and anelastic phenomena appear as distinctive terms in the stiffness matrix. The parameters of the model are nine orthotropic elastic moduli, three angles of orientation of the material principal directions and three parameters governing the anelastic frequency dependence. The inverse estimation consists in numerically fitting the model on a set of transfer functions extracted from a sample of material. The setup uses a seismic-mass measurement repeated in the three directions of space and is placed in a vacuum chamber in order to remove the air from the pores of the sample. The method allows to reconstruct the full frequency-dependent complex stiffness matrix of the frame of an anisotropic open-cell foam and in particular it provides the frequency of maximum energy dissipation by viscoelastic effects. The characterisation of a melamine foam sample is performed and the relation between the fractional-derivative model and other types of parameterisations of the augmented Hooke's law is discussed.

  20. Arrays of ZnO nanorods decorated with Au nanoparticles as surface-enhanced Raman scattering substrates for rapid detection of trace melamine

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Zao [College of Physics and Electronics, Central South University, Changsha 410083 (China); Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Yi, Yong [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Luo, Jiangshan; Li, Xibo [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang, 621900 (China); Xu, Xibin [College of Physics and Electronics, Central South University, Changsha 410083 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Jiang, Xiaodong [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang, 621900 (China); Yi, Yougen, E-mail: yougenyi@mail.csu.edu.cn [College of Physics and Electronics, Central South University, Changsha 410083 (China); Tang, Yongjian [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang, 621900 (China)

    2014-10-15

    In this paper, as a new, highly sensitive and uniform hybrid surface-enhanced Raman scattering (SERS) substrate, arrays of ZnO nanorods (ZnO-NRs) decorated with Au nanoparticles (Au-NPs) have been prepared. This hybrid substrate manifests high SERS sensitivity to melamine and a detection limit as low as 1.0×10{sup −10} M (1.26 µg L{sup −1}). A maximum enhancement factor of 1.0×10{sup 9} can be obtained with the ZnO NF–Au (sample 2) film. Au-NPs gaps in the array can create lots of SERS “hot spots” that mainly contribute to the high SERS sensitivity. Moreover, the supporting chemical enhancement effect of ZnO-NRs and the better enrichment effect ascribed to the large surface area of the substrate also help to achieve a lower detection limit. The promising advantages of easy sample pretreatment, short detection time and low cost makes the arrays of ZnO-NRs decorated with Au-NPs substrate a potential detection tool in the field of food safety.

  1. In Situ Carbon Coated LiNi0.5Mn1.5O4 Cathode Material Prepared by Prepolymer of Melamine Formaldehyde Resin Assisted Method

    Directory of Open Access Journals (Sweden)

    Wei Yang

    2016-01-01

    Full Text Available Carbon coated spinel LiNi0.5Mn1.5O4 were prepared by spray-drying using prepolymer of melamine formaldehyde resin (PMF as carbon source of carbon coating layer. The PMF carbon coated LiNi0.5Mn1.5O4 was characterized by XRD, SEM, and other electrochemical measurements. The as-prepared lithium nickel manganese oxide has the cubic face-centered spinel structure with a space group of Fd3m. It showed good electrochemical performance as a cathode material for lithium ion battery. After 100 discharge and charge cycles at 0.5 C rate, the specific discharge capacity of carbon coated LiNi0.5Mn1.5O4 was 130 mAh·g−1, and the corresponding capacity retention was 98.8%. The 100th cycle specific discharge capacity at 10 C rate of carbon coated LiNi0.5Mn1.5O4 was 105.4 mAh·g−1, and even the corresponding capacity retention was 95.2%.

  2. Simple and fast preparation of graphene oxide@ melamine terephthaldehyde and its PVC nanocomposite via ultrasonic irradiation: Chemical and thermal resistance study.

    Science.gov (United States)

    Khaleghi, Mahroo; Didehban, Khadijeh; Shabanian, Meisam

    2018-05-01

    Melamine terephthaldehyde modified graphene oxide (MTR-GO) with optimum content was easily prepared via ultrasonication method and used as anti-corrosion additive for Poly (vinyl chloride) (PVC). The effects of ultrasonicated MTR-GO on the mechanical, chemical and thermal resistance of the PVC were thoroughly studied. Change percentage of tensile strength and weight change percentage of PVC (P) and PVC/MTR-GO nanocomposite (PN) in acetone and sodium hypochlorite (NaClO) media at two different exposure temperature (20 °C and 50 °C) were examined. The PN sample showed lower change loss percentage of tensile strength in acetone uptake as compared with P sample at 20 °C. In higher temperature (50 °C), P sample was decomposed while PN still showed tensile data. The change loss percentage in tensile strength of PN sample showed 13% change at 50 °C in sodium hypochlorite while P sample showed 63% change for the parameter. Protective behavior of MTR-GO nanofiller on PVC matrix against thermal HCl releasing was investigated by Congo red tests. The results showed that the nanocomposite release less amount of HCl as compare to the neat PVC. Copyright © 2017. Published by Elsevier B.V.

  3. Novel halogen-free flame retardant thermoset from a hybrid hexakis (methoxymethyl melamine/phosphorus-containing epoxy resin cured with phenol formaldehyde novolac

    Directory of Open Access Journals (Sweden)

    2009-12-01

    Full Text Available This paper describes the curing behaviours, thermal properties and flame-resistance of a novel halogen-free epoxy hybrid thermoset, prepared by the curing reaction of hexakis (methoxymethyl melamine (HMMM, a phosphorouscontaining epoxy resin (EPN-D with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO group and phenol formaldehyde novolac (n-PF. The resultant thermosets showed high glass-transition temperatures (Tg, 123–147°C as determined by thermal mechanical analysis (TMA, excellent thermal stability with high 5 wt% decomposition temperatures (Td,5% ≥308°C and high char yields (Yc ≥39.4 wt% from the thermogravimetric analysis (TGA. All the cured EPND/ HMMM/n-PF hybrid resins achieved the UL 94 V-0 grade with high limited oxygen indices (LOI > 45.7. It is found that phosphorous and nitrogen elements in the cured EPN-D/HMMM/n-PF hybrid resins had a positive synergistic effect on the improvement of the flame retardancy.

  4. Highlighting the relative effects of surface characteristics and porosity on CO2 capture by adsorbents templated from melamine-based polyaminals

    Science.gov (United States)

    Rehman, Adeela; Park, Soo-Jin

    2018-02-01

    Heteroatom doping along with well-tuned porosity are considered as significant characteristics of a porous carbon material for various potential applications. However, it is a challenging task to tune a single parameter while retaining the other variables unaffected, and this is considered a limiting factor in rational and systematic research. In the present work, in situ nitrogen-enriched microporous carbon materials were prepared by direct carbonization of conjugated porous polyaminals at two different temperatures. To evaluate the role of nitrogen doping in gas adsorption, a comparison was made with commercially available high-surface-area (2093 m2/g) microporous petroleum-pitch-based activated carbon (AC) deprived of nitrogen functionalities. It was found that the CO2 adsorption capacity of MPA-2-700, carbonized melamine based polyaminal at 700 °C, (186.1 mg/g at 273 K/1 bar with a surface area of 403 m2/g) was significantly higher than that of AC (111.0 mg/g at 273 K/1 bar). Our results present valuable insight into designing porous adsorbents with optimized surface polarity and textural characteristics as promising candidates for CO2 capture.

  5. One-step synthesis of graphitic carbon nitride nanosheets with the help of melamine and its application for fluorescence detection of mercuric ions.

    Science.gov (United States)

    Zhuang, Qianfen; Sun, Liming; Ni, Yongnian

    2017-03-01

    A facile, simple, and relatively environment-friendly hydrothermal approach was developed for one-step synthesis of graphitic carbon nitride nanosheets (GCNNs) using melamine and sodium citrate as the precursors. The prepared GCNNs emit strong fluorescence with a high quantum yield of 48.3%. The GCNNs were then characterized by various techniques including transmission electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and UV-Vis absorption spectroscopy. In addition, the fluorescence quenching behavior of the GCNNS by mercuric ions (Hg 2+ ) was exploited to fabricate a label-free fluorescence quenching sensor for sensitive and selective detection of Hg 2+ . The results showed that there existed a linear relationship between the fluorescence intensity and the concentration of Hg 2+ from 0.001 to 1.0μM with a detection limit of 0.3nM. Finally, the sensor was successfully used to detection of Hg 2+ in water and milk samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. A novel colloidal gold-based lateral flow immunoassay for rapid simultaneous detection of cyromazine and melamine in foods of animal origin.

    Science.gov (United States)

    Le, Tao; Yan, Peifeng; Xu, Jian; Hao, Youjing

    2013-06-01

    A rapid and sensitive lateral flow immunoassay (LFIA) based on competitive format was developed and validated for simultaneous detection of cyromazine (CA) and melamine (MA) in foods of animal origin. With this method, the cut-off value for the two test lines were achieved at 25 ng/g, which was lower than the maximum residue levels (MRLs) established for CA and MA. At three fortified levels (50, 100, and 150 ng/g), the recoveries for CA and MA ranged from 73.9% to 104.2% with the relative standard deviation (RSD) less than 11.9%, based on within day and interday analysis. The lower detection limit for CA and MA in matrix sample were 0.22 ng/ml and 0.26 ng/ml, respectively, which were lower than those of published literatures. A parallel analysis of CA and MA in real samples conducted by HPLC showed comparable results to those obtained from LFIA. The results of LFIA were in good agreement with those of high performance liquid chromatography (HPLC) in the analysis of CA and MA in foods of animal origin, demonstrating the practical applicability of the developed assay in real samples. Overall, to our knowledge, this is the first report of quantitative or semi-quantitative simultaneous detection for CA and MA by immunochromatographic assay. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. One-step, room temperature, colorimetric melamine sensing using an in-situ formation of silver nanoparticles through modified Tollens process

    Science.gov (United States)

    Wang, Huiying; Chen, Dinglong; Yu, Longquan; Chang, Ming; Ci, Lijie

    2015-02-01

    We have developed a rapid, sensitive, one-step, and selective colorimetric detection method for melamine (MEL) in milk powder based upon an in-situ formation of silver nanoparticles (AgNPs) through modified Tollens process at room temperature. The triazine ring N atoms of MEL molecule were strategically designed to complex the Ag+ through electron donor-acceptor interaction. During the AgNPs formation procedure, the MEL molecule, which has been covalently bonded with the Ag+ ions, was adsorbed to the surface of as-prepared AgNPs, resulting in the aggregation of the adjacent AgNPs with detectable decreases of absorption signal. The concentration of MEL can be determined with the naked eye or a UV-vis spectrometer at which the yellow-to-brown color change associated with aggregate enhancement takes place. This method enables rapid (less than 30 min) and sensitive (limit of detection, LOD, 10 nM) detection, and it was also able to discriminate MEL from sixteen other milk relevant coexisting compounds. This assay does not utilize organic cosolvents, enzymatic reactions, light-sensitive dye molecules, lengthy protocols, or sophisticated instrumentation thereby overcoming some of the limitations of conventional methods.

  8. Melamine Trisulfonic Acid: An Efficient, Heterogeneous and Reusable Catalyst for the Synthesis of 10-Aryl-6,8-dimethyl- 6, 10-dihydro-5-oxa-6,8-diazaanthra [2,3-d][1,3]dioxole- 7,9-diones

    Directory of Open Access Journals (Sweden)

    Weilin Li

    2011-01-01

    Full Text Available Melamine trisulfonic acid was used as an efficient and recyclable catalyst for the one-pot synthesis of 10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-diones by condensation of 3,4-methylene dioxyphenol, aromatic aldehydes and 1,3-dimethylbarbituric acid under solvent-free conditions. Different types of aromatic. aldehydes were used in the reaction and in all cases the products were obtained in good to excellent yields.

  9. Sensitive and selective determination of gallic acid in green tea samples based on an electrochemical platform of poly(melamine) film

    Energy Technology Data Exchange (ETDEWEB)

    Su, Ya-Ling; Cheng, Shu-Hua, E-mail: shcheng@ncnu.edu.tw

    2015-12-11

    In this work, an electrochemical sensor coupled with an effective flow-injection amperometry (FIA) system is developed, targeting the determination of gallic acid (GA) in a mild neutral condition, in contrast to the existing electrochemical methods. The sensor is based on a thin electroactive poly(melamine) film immobilized on a pre-anodized screen-printed carbon electrode (SPCE*/PME). The characteristics of the sensing surface are well-characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The proposed assay exhibits a wide linear response to GA in both pH 3 and pH 7.0 phosphate buffer solutions (PBS) under the optimized flow-injection amperometry. The detection limit (S/N = 3) is 0.076 μM and 0.21 μM in the pH 3 and pH 7 solutions, respectively. A relative standard deviation (RSD) of 3.9% is obtained for 57 successive measurements of 50 μM GA in pH 7 solutions. Interference studies indicate that some inorganic salts, catechol, caffeine and ascorbic acid do not interfere with the GA assay. The interference effects from some orthodiphenolic compounds are also investigated. The proposed method and a conventional Folin–Ciocalteu method are applied to detect GA in green tea samples using the standard addition method, and satisfactory spiked recoveries are obtained. - Highlights: • A nitrogen-rich conducting polymer was used for electroanalysis of gallic acid. • The sensor exhibits excellent electrochemical activity in both acidic and neutral media. • Good analytical results in terms of low detection limit and wide linear range are obtained. • The flow-injection amperometric assay is highly stable for continuous 57 replicates measurement (RSD = 3.9%). • The assay shows good recovery for green tea samples.

  10. Microencapsulation of butyl stearate with melamine-formaldehyde resin: Effect of decreasing the pH value on the composition and thermal stability of microcapsules

    Directory of Open Access Journals (Sweden)

    M. Krajnc

    2012-10-01

    Full Text Available The object of this study was to investigate how different decreasing of pH regimes during microencapsulation process with melamine-formaldehyde (MF resin affects the composition, morphology and thermal stability of microcapsules containing a phase-change material (PCM. Technical butyl stearate was used as PCM. Microencapsulation was carried out at 70°C. For all experiments the starting pH value was 6.0. After one hour of microencapsulation at the starting pH value, the pH value was lowered to final pH value (5.5; 5.0; 4.5 in a stepwise or linear way. The properties of microcapsules were monitored during and after the microencapsulation process. The results showed that pH value decreasing regime was critical for the morphology and stability of microcapsules. During microencapsulations with a stepwise decrease of pH value we observed faster increase of the amount of MF resin in the microencapsulation product compared to the microencapsulations with a linear pH value decrease. However, faster deposition in the case of microencapsulations with stepwise decrease of pH value did not result in thicker MF shells. The shell thickness increased much faster when the pH value was decreased in a linear way or in several smaller steps. It was shown that for the best thermal stability of microcapsules, the pH value during microencapsulation had to be lowered in a linear way or in smaller steps to 5.0 or lower.

  11. Melamine-based dendrimer amine-modified magnetic nanoparticles as an efficient Pb(II) adsorbent for wastewater treatment: Adsorption optimization by response surface methodology.

    Science.gov (United States)

    Jiryaei Sharahi, Fatemeh; Shahbazi, Afsaneh

    2017-12-01

    Magnetic Fe 3 O 4 nanoparticles with an average diameter of 64 nm was synthesized solvothermically and subsequently modified with melamine-based dendrimer amine (MDA-Fe 3 O 4 ) via grafting method. The synthesized materials were characterized using DLS, SEM, XRD, FTIR, VSM, TGA and elemental analysis techniques. The MDA-Fe 3 O 4 was employed for the efficient removal of Pb(II) ions from an aqueous solution. The adsorption efficiency was investigated in relation to the independent variables of Pb(II) concentration (80-250 mg L -1 ), pH of the solution (3-7), adsorbent dosage (0.1-0.5 g L -1 ) and temperature (10-40 °C) via a central composite design (CCD) using response surface methodology (RSM). The significance of independent variables and their interactions was tested using ANOVA at a 95% confidence limit (α = 0.05). A second-order quadratic model was established to predict the adsorption efficiency. Under the optimum condition (initial Pb(II) concentration = 110 mg L -1 , MDA-Fe 3 O 4 dosage = 0.49 g L -1 , pH = 5 and temperature = 30 °C) a removal percentage of 85.6% was obtained. The isotherm data fitted well to the Freundlich model within the concentration range of the experimental study. A maximum adsorption capacity of 333.3 mg g -1 was predicted by the Langmuir model. The adsorption rate of Pb(II) ions onto MDA-Fe 3 O 4 was in good agreement with the pseudo-second-order model (R 2  = 0.999; k 2  = 4.7 × 10 -4  g mg -1 min -1 ). Thermodynamically, adsorption was spontaneous and endothermic. The MDA-Fe 3 O 4 was successfully regenerated using 0.3 M HCl with little loss of adsorption capacity (≈7%) for five successive adsorption cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Melamin Plaka İle Kaplanmış Yonga Levhalı (YL-Lam Kutu Mobilyalarda Köşe Birleştirmelerin Yük Taşıma Kapasitesi

    Directory of Open Access Journals (Sweden)

    Mustafa ALTINOK

    2014-02-01

    Full Text Available Kutu mobilya köşe birleştirmelerindeki mukavemet, bu tip ürünlerin kullanım sürelerini doğrudan etkilemektedir. Mukavemeti etkileyen etmenler ise üretim aşamasında seçilen levha, köşe birleştirme tipi ve tutkaldır. Bu çalışmada, karma birleştirme (kavela+yabancı çıtalı yöntemiyle birleştirilmiş melamin plaka ile kaplanmış yonga levha (YL-Lam örneklerde kullanılan farklı tutkalların kutu mobilya köşe birleştirmelerindeki diyagonal zorlamalar (diyagonal basınç ve çekme karşısındaki mukavemet performansları araştırılmıştır. Bu amaçla, faklı tutkal türleri (PVAc, Polimerin, Silikon ile tutkallanmış karma köşe birleştirmeli YL- Lam örnekler hazırlanmıştır. Örneklere diyagonal basınç ve çekme deneyleri uygulanmıştır. Deneyler sonunda silikon tutkallı deney örneklerinde, diğer örneklerden daha yüksek basınç ve çekme direnci tespit edilmiştir. Anahtar kelimeler: Yapıştırıcı, Ahşap Birleştirme, Diyagonal Basma Direnci, Diyagonal Çekme Direnci

  13. Thermal removal of nitrogen species from wood waste containing urea formaldehyde and melamine formaldehyde resins

    Energy Technology Data Exchange (ETDEWEB)

    Girods, P. [LERMAB, Nancy-Universite, UMR 1093, INRA, ENGREF, UHP, ENSTIB 27, rue du Merle Blanc, BP 1041, 88 051 Epinal (France)], E-mail: pierre.girods@yahoo.fr; Dufour, A.; Rogaume, Y.; Rogaume, C.; Zoulalian, A. [LERMAB, Nancy-Universite, UMR 1093, INRA, ENGREF, UHP, ENSTIB 27, rue du Merle Blanc, BP 1041, 88 051 Epinal (France)

    2008-11-30

    The removal of nitrogen from wood board waste through a low temperature pyrolysis (523-573 K) is investigated with two analytical methods. The kinetic study of the thermal behaviour of wood board and of its components (wood, UF and MF resins) shows the feasibility of removing thermally nitrogen from wood board waste. Indeed, the range of temperatures associated with the degradation of wood is different from the one obtained for the degradation of UF and MF resin. Isothermal conditions enable the determination of a kinetic model for degradation of wood board and of its components and demonstrate that the thermal behaviour of wood board is not the reflection of the sum of its components' behaviour. FTIR analysis of gas products confirms the feasibility removing nitrogen thermally and enables the evaluation of the optimum treatment conditions (temperature/duration). Elementary analysis of the treated samples and study of their low heating value (LHV) enable to quantify the efficiency of the thermal treatment in terms of nitrogen removal and of energy recovery. Results show that around 70% of the initial nitrogen can be removed from the waste, and that the temperature of treatment (between 523 K and 573 K) does not influence the efficiency in terms of nitrogen removal. Nevertheless, the ratio Residual energy/Initial energy (between 76% and 90%) is improved with the lowest temperature of treatment.

  14. Novel Supramolecular Polymer Networks Based on Melamine- and Imide-Containing Oligomers

    NARCIS (Netherlands)

    Loontjens, Ton; Put, Jos; Coussens, Betty; Palmen, Jo; Sleijpen, Ton; Plum, Bart

    2001-01-01

    Reversible, supramolecular polymer networks based on commercially available bulk chemicals, and prepared using an industrially attractive route are described. The difunctional, low molecular weight polytetramethyleneoxide is functionalized with trimellitic imide, and reversibly crosslinked with the

  15. Molecularly Imprinted Porous Monolithic Materials from Melamine-Formaldehyde for Selective Trapping of Phosphopeptides

    DEFF Research Database (Denmark)

    Liu, Mingquan; Tran, Tri Minh; Abbas Elhaj, Ahmed Awad

    2017-01-01

    and triblock copolymeric surfactants as porogens and mesoporogens, respectively. By varying the prepolymer composition and the type and molecular weight of the polymeric porogen components, a library of porous monolithic materials was produced, covering a range of meso- and macroporous properties....... A multivariate evaluation revealed that the amount of surfactant was the strongest contributor to specific surface area and pore volume and to the inversely related mesopore size, whereas the macropore dimensions were controlled mainly by the amount of aliphatic polyether porogen. One of these capillary...

  16. a study of the kinetic of synthesis and crosslinking of methylol ...

    African Journals Online (AJOL)

    Nurudeen

    A STUDY OF THE KINETIC OF SYNTHESIS AND CROSSLINKING. OF METHYLOL MELAMINE. Nurudeen Ayeni and ... Keywords: Kinetic, Synthesis, Melamine. INTRODUCTION. Melamine formaldehyde resins are much ... Liquid Ammonia Pre-treatment on the Crease. Recovery Properties of Resinated Cellulose. Fabrics.

  17. Preparation of Melamine - Formaldehyde Microcapsules Containing Hexadecane as a Phase Change Material: The Effect of Surfactants Type and Concentration

    Directory of Open Access Journals (Sweden)

    Zeinab Alinejad

    2013-05-01

    Full Text Available Microcapsules containing n-hexadecane (HD as the core and melamineformaldehyde (MF prepolymer as the shell were prepared by in-situ dispersion polymerization. The effects of surfactants type and amount were studied in relation to the morphology and thermal properties of microcapsules. The morphology of the microcapsules was studied using scanning electron microscopy (SEM and thermal properties were detected by differential scanning calorimetry (DSC and thermogravimetric analysis (TGA. SEM images showed that the increase in the amount of Triton X-100 (non-ionic to SDS (ionic ratio resulted in the agglomeration of the prepared microcapsules. This increase led also to lower encapsulated hexadecane and thermal stability of microcapsules. As a result, the optimum composition of the above surfactants for obtaining higher thermal stability and proper morphology wasfound to be 20 wt% of Triton X-100 and 80 wt% of SDS in the recipe. The optimum total amounts of surfactants was 4 wt%, which resulted in spherical and separate microcapsules. DSC and TGA analyses revealed that a sample prepared with 4 wt% of surfactants was not only successful in encapsulation of hexadecane but also showedhigher thermal stability compared with other formulations.

  18. Synthesis high specific surface area nanotube g-C3N4 with two-step condensation treatment of melamine to enhance photocatalysis properties

    OpenAIRE

    Jin, Zhengyuan; Zhang, Qitao; Yuan, Saisai; Ohno, Teruhisa

    2015-01-01

    High specific surface area nanotube g-C3N4 was fabricated by a simple two-step condensation method. Photocatalytic activity was evaluated by decomposition of Rhodamine B (Rh B) under visible light. Nanotube g-C3N4 showed 12 times higher photocatalytic activity than bulk g-C3N4. The improvement of photocatalytic activity was mainly due to the higher surface area, the unique morphology and the number of defects.

  19. Uniform Fe3O4/Nitrogen-Doped Mesoporous Carbon Spheres Derived from Ferric Citrate-Bonded Melamine Resin as an Efficient Synergistic Catalyst for Oxygen Reduction.

    Science.gov (United States)

    Wang, Haitao; Wang, Wei; Gui, Mengxi; Asif, Muhammad; Wang, Zhengyun; Yu, Yang; Xiao, Junwu; Liu, Hongfang

    2017-01-11

    Developing a facile strategy to synthesize an efficient and inexpensive catalyst for the oxygen reduction reaction (ORR) is critical to the commercialization of many sustainable energy storage and conversion techniques. Herein, a novel and convenient strategy was presented to prepare Fe 3 O 4 embedded into nitrogen-doped mesoporous carbon spheres (Fe 3 O 4 /N-MCS) by the polycondensation between methylolmelamines and ammonium ferric citrate (AFC) and subsequent pyrolysis process. In particular, the polycondensation reaction was completely finished within a very short time (6.5 min), and the iron contents can be adjusted and had a great influence on the microstructure. Moreover, the Fe 3 O 4 /N-MCS can be used as a robust catalyst for the ORR in alkaline media, and the catalyst with the iron content of 3.35 wt % exhibited excellent electrochemical performance in terms of more positive onset potential (E 0 = 1.036 V vs RHE) and half-wave potential (E 1/2 = 0.861 V) and much better methanol tolerance and long-term durability, in comparison with that of 20% Pt/C. The remarkable performance was ascribed to the characteristics of large specific surface area, mesoporous structure, high contents of pyridinic N and graphitic N, as well as strong electronic interaction between Fe 3 O 4 and protective N-doped graphitic layers.

  20. Dendritic Ni-P-coated melamine foam for a lightweight, low-cost, and amphipathic three-dimensional current collector for binder-free electrodes.

    Science.gov (United States)

    Huang, Xiao-lei; Xu, Dan; Yuan, Shuang; Ma, De-long; Wang, Sai; Zheng, Huai-yu; Zhang, Xin-bo

    2014-11-12

    A highly conductive 3D current collector that is dendritic, lightweight, and robust is synthesized for binder-free electrodes in lithium-ion batteries. It has excellent chemical/electrochemical stability in a wide voltage window (0-5 V) and robust mechanical behavior even after 600 cycles of compression. When active materials are grown in situ on the as-obtained current collector, the resulting cycling stability and rate capability far exceed those of conventional electrodes and other 3D current collectors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The European Food Import Safety Regime under a ‘Stress Test’: The Melamine Contamination of the Global Food Supply Chain

    NARCIS (Netherlands)

    A. Alemanno (Alberto)

    2010-01-01

    textabstractEnsuring that European food imports are safe presents special challenges, as production takes place in third countries outside the direct control of the member states. Yet, contrary to conventional wisdom, besides a few exceptions regarding high-risk products (such as animals and animal

  2. Impact of cold temperatures on the shear strength of Norway spruce joints glued with different adhesives

    DEFF Research Database (Denmark)

    Wang, Xiaodong; Hagman, Olle; Sundqvist, Bror

    2015-01-01

    × 20 mm × 10 mm) were bonded with seven commercially available adhesives: polyurethane (PUR), polyvinyl acetate (PVAc), emulsion-polymer-isocyanate (EPI), melamine-formaldehyde (MF), phenol-resorcinol-formaldehyde (PRF), melamine-urea-formaldehyde1 (MUF1), and melamine-urea-formaldehyde2 (MUF2). Each...

  3. 2008 Chinese Milk Products Crisis

    Directory of Open Access Journals (Sweden)

    Rini Ariani Basyamfar

    2014-10-01

    Abstrak. Susu merupakan salah satu produk pangan yang paling penting untuk pertumbuhan anak-anak dan kesehatan. Melamin (2,4,6-triazina-1,3,5-triamino adalah senyawa organik yang digunakan dalam pembuatan pestisida, plastik, pembersih, dan disinfektan. Melamin ketika ditambahkan ke susu meningkatkan jumlah keseluruhan nitrogen dalam susu sehingga mengelabui tes umum untuk kandungan protein. Melamin juga sangat berbahaya bila tertelan, terutama untuk anak-anak. Sanlu, salah satu produsen susu terbesar di China, mengencerkan produk susu mereka dengan air dan menambahkan melamin untuk mengelabui tes protein. Konsumsi susu yang mengandung melamin dalam jumlah yang lebih besar dari 1 mg/kg dapat menyebabkan gagal ginjal, kanker kandung kemih dan kematian. Pengujian susu menggunakan LC-MS/MS dan metode GC-MS/MS dapat mengungkapkan kontaminasi melamin. Tindakan lebih lanjut yang dapat diterapkan untuk mengurangi pemalsuan susu antara lain penelusuran produk, transparansi perusahaan, 100% prosedur pengujian produk dan penegakan hukum yang konsisten.

  4. Synthesis and curing of alkyd enamels based on ricinoleic acid

    OpenAIRE

    Jovičić Mirjana C.; Radičević Radmila Ž.; Simendić Vesna B.

    2010-01-01

    A combination of an alkyd resin with a melamine-formaldehyde resin gives a cured enamel film with the flexibility of the alkyd constituent and the high chemical resistance and hardness of the melamine resin at the same time. The melamine resin is a minor constituent and plays the role of a crosslinking agent. In this paper, alkyd resins of high hydroxyl numbers based on trimethylolpropane, ricinoleic acid and phthalic anhydride were synthesized. Two alkyds having 30 and 40 wt% of ricino...

  5. Flame and Blast Resistant Materials for Force Protection

    Science.gov (United States)

    2012-06-29

    search for other additives that could be useful*. This Navy-funded work segued into the Air Force-sponsored work, which is the subject of this final...Supplier Decabromodiphenyl oxide Albemarle Antimony Oxide Laurel Industries Ammonium Polyphosphate ICL Melamine BASF Melamine Polyphosphate BASF

  6. New hybrid halogen-free flame retardants

    Science.gov (United States)

    Kijowska, Dorota; Jankowski, Piotr

    2014-05-01

    The main objective of this work were researches concerning the methods of the in-situ modification of silicate layer-tubular mineral (SL-TM) halloysite, using the salts of melamine, i.e. melamine cyanurate. The modified mineral was used as flame retardant to thermoplastic polymers. In the case of the application of halloysite modified by melamine cyanurate to polyamide 6 (PA6) the highest parameters of vertical and horizontal flammability were achieved. The mechanical properties of filled polyamide 6 have been improved.

  7. Radiation processing of polymer emulsion, (2)

    International Nuclear Information System (INIS)

    Makuuchi, Keizo; Katakai, Akio; Ito, Hiroshi; Araki, Kunio; Takagi, Toru.

    1980-01-01

    The crosslinking characteristics of hydroxylated acrylic emulsions irradiated with Co-60 γ rays were investigated by measuring the gel fractions of the films baked with melamine resin. Cure response of the irradiated emulsions increased with increasing dose, owing to the crosslinking of the polymers in the emulsion particles by radiation. The irradiated emulsions were crosslinked with melamine resin at lower temperature than the unirradiated emulsion. Crosslinking in the particles by radiation and crosslinking between particles with melamine resin at the elevated temperatures were dependent on the distribution of hydroxyl groups in the particles. Localization of hydroxyl groups near the particle surface did not facilitated both kinds of crosslinking. (author)

  8. Developing Sensitive and Selective Nanosensors: A Single Molecule - Multiple Excitation Source Approach. Altairnano Lithium Ion Nano-scaled Titanate Oxide Cell and Module Abuse Testing

    Science.gov (United States)

    2012-03-13

    Melamine 6013ppmin EtOH NA Silver Terpyridine 120ppm in EtOH NA Coumarin -1 62.5ppm in EtOH Pure, laser grade, ARCOS ORGANICS, C14H17NO2 Melamine...Eu/Tb/Sm/Dy) 9067ppm in EtOH NA Melamine (Eu/Tb/Dy/Sm) 4000ppm in EtOH NA Melamine (EuLotd)3/Tb/Sm/Dy 760ppm in EtOH NA Coumarin -152 1000ppm in...EtOH C12H10F3NO2 Coumarin -334 125ppm in EtOH 99% Pure, laser grade, ARCOS ORGANICS Coumarin -6 62.5ppm in EtOH 98% Pure, laser grade, ARCOS

  9. Precursor polymer compositions comprising polybenzimidazole

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  10. Polymer compositions, polymer films and methods and precursors for forming same

    Science.gov (United States)

    Klaehn, John R; Peterson, Eric S; Orme, Christopher J

    2013-09-24

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  11. Noise Transmission Studies of an Advanced Grid-Stiffened Composite Fairing

    National Research Council Canada - National Science Library

    Lane, Steven A; Kennedy, Scott; Richard, Robert

    2007-01-01

    .... These tests were performed in an acoustics laboratory and examined the effects of acoustic flanking paths, the thermal protection system, and melamine-type acoustic blanket treatments on fairing noise...

  12. Presidential Green Chemistry Challenge: 2009 Greener Reaction Conditions Award

    Science.gov (United States)

    Presidential Green Chemistry Challenge 2009 award winner, CEM Corporation, developed a fast, automated analytical process using less toxic reagents and less energy to distinguish protein from the food adulterant, melamine.

  13. Photocatalytic degradation of methylene blue by C3N4/ZnO: the ...

    Indian Academy of Sciences (India)

    Abstract. The C3N4/ZnO composite photocatalysts were synthesized by mechanical milling combined with a calcination process. Various ratios of melamine and ZnO powders were milled by a planetary ball mill for 10 h. After heating at 540◦C for 3 h in air, melamine was converted to C3N4 but the formation of C3N4 ...

  14. Effectiveness of Flame Retardants in TufFoam.

    Energy Technology Data Exchange (ETDEWEB)

    Abelow, Alexis Elizabeth [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Nissen, April [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Massey, Lee Taylor [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Whinnery, LeRoy L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2017-12-01

    An investigation of polyurethane foam filled with known flame retardant fillers including hydroxides, melamine, phosphate-containing compounds, and melamine phosphates was carried out to produce a low-cost material with high flame retardant efficiency. The impact of flame retardant fillers on the physical properties such a s composite foam density, glass transition temperature, storage modulus, and thermal expansion of composite foams was investigated with the goal of synthesizing a robust rigid foam with excellent flame retardant properties.

  15. Synthesis and enhanced photocatalytic activity of g-C3N4 ...

    Indian Academy of Sciences (India)

    70

    2.1 Preparation of C3N4/CdS nanocomposites. The C3N4 powder was prepared by a facile thermal polycondensation of melamine in air. Typically, 5 g of melamine powder was put into a crucible, and then heated to 520 °C in muffle furnace with a rate of 10 °C·min-1 for 4 h. The C3N4/CdS nanocomposites were prepared ...

  16. The effect of type and mixture of resin on the properties of impregnated paper

    Directory of Open Access Journals (Sweden)

    hossein Kermanian

    2017-05-01

    Full Text Available This study was carried out in order to investigate the effects of different types of resins and also their mixtures on the impregnated paper properties. In this regard, pure urea resin (100%, mixture of melamine and urea resins with various combinations (60/40 and 70/30 and 50/50, mixture of nano-fiber cellulose ratios of 1, 2 and 3 percent with urea resin and pure PVA (100% were used to impregnate of newsprint basic paper of Mazandaran wood and paper industries. Immersion of samples in the impregnation step were done in two time of 5 and 10 seconds. Next, melamine resin was used for surface coating and then absorption of resin in the impregnation and coating process measured. Results showed that in the impregnation step with pure urea (100%, in the respect of absorption rate and surface properties of melamine paper, the best time of impregnation was obtained 10 seconds. In the combined treatment, adding up to 30% melamine to urea resin, as impregnation step resin, offers better properties in terms of stain resistance, cigarette resistance, resistance to cracking and resistance to hot water steam for impregnatedmade paper. By adding nanocellulose up to 1% in impregnation resin, better properties is obtained for melamine paper. Also, PVA as impregnation resin, can be offer similar quality to pure urea in the resulting melamine papers.

  17. Synthesis and curing of alkyd enamels based on ricinoleic acid

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana C.

    2010-01-01

    Full Text Available A combination of an alkyd resin with a melamine-formaldehyde resin gives a cured enamel film with the flexibility of the alkyd constituent and the high chemical resistance and hardness of the melamine resin at the same time. The melamine resin is a minor constituent and plays the role of a crosslinking agent. In this paper, alkyd resins of high hydroxyl numbers based on trimethylolpropane, ricinoleic acid and phthalic anhydride were synthesized. Two alkyds having 30 and 40 wt% of ricinoleic acid were formulated by calculation on alkyd constant. Alkyds were characterized by FTIR and by the determination of acid and hydroxyl numbers. Then synthesized alkyds were made into baking enamels by mixing with melamine-formaldehyde resins (weight ratio of 70:30 based on dried mass. Two types of commercial melamine resins were used: threeisobutoxymethyl melamine-formaldehyde resin (TIMMF and hexamethoxymethyl melamine resin (HMMMF. Prepared alkyd/melamine resin mixtures were cured in a differential scanning calorimeter (DSC under non-isothermal mode. Apparent degree of curing as a function of temperature was calculated from the curing enthalpies. Kinetic parameters of curing were calculated using Freeman-Carroll method. TIMMF resin is more reactive with synthesized alkyds than HMMMF resin what was expected. Alkyd resin with 30 wt% of ricinoleic acid is slightly more reactive than alkyd with 40 wt% of ricinoleic acid, probably because it has the high contents of free hydroxyl and acid groups. The gel content, Tg, thermal stability, hardness, elasticity and impact resistance of coated films cured at 150°C for 60 min were measured. Cured films show good thermal stability since the onset of films thermal degradation determined by thermogravimetric analysis (TGA is observed at the temperatures from 281 to 329°C. Films based on alkyd 30 are more thermal stable than those from alkyd 40, with the same melamine resin. The type of alkyd resin has no significant

  18. One step synthesis of P-doped g-C3N4 with the enhanced visible light photocatalytic activity

    Science.gov (United States)

    Liu, Sen; Zhu, Honglei; Yao, Wenqing; Chen, Kai; Chen, Daimei

    2018-02-01

    In our work, P doped Graphitic nitride (g-C3N4) was prepared by the simple copolymerization of melamine and melamine phosphate. The melamine phosphate ester polymer is a complex of an s-triazine and phosphoric acid polymer, thus it will be favourable for P atom to incorporate into the Csbnd N network of g-C3N4. The doped P atoms may produce the delocalized lone electron and form the Lewis acid sites. The obtained P-doped g-C3N4 showed the higher photocatalytic activity in photodegradation of MB and 2,4-Dichlorophenol than g-C3N4. The optimum photocatatlytic activity of P-C3N4 with the weight ration of melamine phosphate and melamine at 0.06 is 2 times as higher as the pure g-C3N4 in MB photodegradation, and 1.5 times higher in 2,4-Dichlorophenol photodegradation. The enhancement of photodegradation efficiency is due to the delocalization effect of lone electron, promoting the separation of photogenerated charges, and the larger band gap of P doped g-C3N4.

  19. Identification and characterization of toxicity of contaminants in pet food leading to an outbreak of renal toxicity in cats and dogs.

    Science.gov (United States)

    Dobson, Roy L M; Motlagh, Safa; Quijano, Mike; Cambron, R Thomas; Baker, Timothy R; Pullen, Aletha M; Regg, Brian T; Bigalow-Kern, Adrienne S; Vennard, Thomas; Fix, Andrew; Reimschuessel, Renate; Overmann, Gary; Shan, Yuching; Daston, George P

    2008-11-01

    This paper describes research relating to the major recall of pet food that occurred in Spring 2007 in North America. Clinical observations of acute renal failure in cats and dogs were associated with consumption of wet pet food produced by a contract manufacturer producing for a large number of companies. The affected lots of food had been formulated with wheat gluten originating from China. Pet food and gluten were analyzed for contaminants using several configurations of high-performance liquid chromatography (HPLC) and mass spectrometry (MS), which revealed a number of simple triazine compounds, principally melamine and cyanuric acid, with lower concentrations of ammeline, ammelide, ureidomelamine, and N-methylmelamine. Melamine and cyanuric acid, have been tested and do not produce acute renal toxicity. Some of the triazines have poor solubility, as does the compound melamine cyanurate. Pathological evaluation of cats and dogs that had died from the acute renal failure indicated the presence of crystals in kidney tubules. We hypothesized that these crystals were composed of the poorly soluble triazines, a melamine-cyanuric acid complex, or a combination. Sprague dawley rats were given up to 100 mg/kg ammeline or ammelide alone, a mixture of melamine and cyanuric acid (400/400 mg/kg/day), or a mixture of all four compounds (400 mg/kg/day melamine, 40 mg/kg/day of the others). Neither ammeline nor ammelide alone produced any renal effects, but the mixtures produced significant renal damage and crystals in nephrons. HPLC-MS/MS confirmed the presence of melamine and cyanuric acid in the kidney. Infrared microspectroscopy on individual crystals from rat or cat (donated material from a veterinary clinic) kidneys confirmed that they were melamine-cyanuric acid cocrystals. Crystals from contaminated gluten produced comparable spectra. These results establish the causal link between the contaminated gluten and the adverse effects and provide a mechanistic explanation

  20. Laser fragmentation of organic microparticles into colloidal nanoparticles in a free liquid jet

    Science.gov (United States)

    Wagener, Philipp; Barcikowski, Stephan

    2010-11-01

    We present a novel approach for laser fragmentation of melamine cyanurate microcrystals suspended in liquid into colloidal nanoparticles. Laser fragmentation is done by irradiating a liquid jet of melamine cyanurate suspended in water with intense picosecond pulses. The free liquid jet is generated by a nozzle with small diameter and provides a thin liquid filament ( d fildextrin as a neutral polymer and 0.01 wt% polyacrylic acid as a polyelectrolytic polymer. Hydrodynamic size and zeta-potential of the nanoparticles can be controlled by mass fraction of the stabilization agent.

  1. Metachromasy of methylene blue due to aggregation over phosphate-modified polymeric carbon nitride

    Science.gov (United States)

    Lakshminarasimhan, N.; Sangeetha, D. N.; Nivetha, G.

    2017-05-01

    Polymeric carbon nitride in graphitic form (g-C3N4) is an emerging visible light active photocatalyst. In this work, phosphate-modified polymeric carbon nitride (PCN) was synthesized by thermal condensation of melamine in the presence of ammonium dihydrogen phosphate (ADP). The addition of PCN to methylene blue (MB) solution showed the color intensification. The hypsochromic shift in the absorption spectrum of MB is due to metachromasy, a phenomenon in which aggregation of dye molecules occurs over the surface of a material. The polymerization of melamine into carbon nitride and MB trimerization depend on the amount of ADP and nature of phosphate species, respectively.

  2. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Water gas shift (WGS) reaction is an important reaction to generate hydrogen from steam reforming of CO. A new WGS catalyst, Ce1−RuO2− (0 ≤ ≤ 0.1) was prepared by hydrothermal method using melamine as a complexing agent. The Catalyst does not require any pre-treatment. Among the several compositions ...

  3. Process for preparing wastes for non-pollutant disposal

    International Nuclear Information System (INIS)

    Debus, A.A.G.; Rosenstiel, T.L.

    1982-01-01

    In disposing of wastes, especially those containing radioactive or toxic substances, wherein the liquid or finely divided solid waste is mixed with water and a hydraulic binder and allowed to set, the binder used comprises a mixture of calcium sulphate hemihydrate, a water-dispersible melamine formaldehyde resin which when cured is hydrophobic and sufficient cross-linking agent to cure the resin. (author)

  4. Hoogtepunten uit het Journal of Chemical Education 2010

    NARCIS (Netherlands)

    Machiel Stolk

    2010-01-01

    De auteur beschrijft een aantal artikelen uit het Journal of Chemical Education 2010 die interessant en geschikt zijn voor gebruik in het scheikunde onderwijs. De volgende onderwerpen komen aan de orde: pH, plastic, kauwgum, melamine, logica in de chemie, natriumpolyacrylaat, H+-ion en theromolyse

  5. Anodic stripping voltammetry of gold nanoparticles at boron-doped diamond electrodes and its application in immunochromatographic strip tests.

    Science.gov (United States)

    Ivandini, Tribidasari A; Wicaksono, Wiyogo P; Saepudin, Endang; Rismetov, Bakhadir; Einaga, Yasuaki

    2015-03-01

    Anodic stripping voltammetry (ASV) of colloidal gold-nanoparticles (AuNPs) was investigated at boron-doped diamond (BDD) electrodes in 50 mM HClO4. A deposition time of 300 s at-0.2 V (vs. Ag/AgCl) was fixed as the condition for the ASV. The voltammograms showed oxidation peaks that could be attributed to the oxidation of gold. These oxidation peaks were then investigated for potential application in immunochromatographic strip tests for the selective and quantitative detection of melamine, in which AuNPs were used as the label for the antibody of melamine. Linear regression of the oxidation peak currents appeared in the concentration range from 0.05-0.6 μg/mL melamine standard, with an estimated LOD of 0.069 μg/mL and an average relative standard deviation of 8.0%. This indicated that the method could be considered as an alternative method for selective and quantitative immunochromatographic applications. The validity was examined by the measurements of melamine injected into milk samples, which showed good recovery percentages during the measurements. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Curing reactions of palm oil alkyd enamels

    International Nuclear Information System (INIS)

    Tan Boon Yeow; Gan Seng Neon

    2000-01-01

    Amino resins are the most popularly used cross-linking agents for thermosetting coatings. The most common amino resins are those derived from melamine, 2,4,6-triamino-1,3,5-triazine and formaldehyde. They are attractive for developing high performance and low cost coatings to improve performances of other film-forming resins with reactive functional groups such as hydroxyl, carboxylic, and amide groups. Alkyds modified with melamine are mainly used in industrial baking enamels for metal surfaces. Short-oil alkyds containing 38-45% phthalic anhydride and a high proportion of hydroxyl values in the alkyd resins render good compatibility with melamine-formaldehyde resins. However, the actual mechanisms and pathways of the curing reactions involved are still not fully understood. This paper describes three palm oil alkyds, synthesized with high hydroxyl values. Clear coating enamels were made by mixing 4 parts; of alkyd resin with 1 part of a methylated melamine resin. The complex curing reactions of the clear enamel can be illustrated qualitatively by using DSC (Differential Scanning Calorimeter). Thermogravimetric analysis (TGA) was used to set suitable curing temperatures without degradation. The dry hard time with various curing temperatures was examined. Fourier transform infrared (FTIR) spectroscopy has been used to follow the changes in functional group concentrations as a function of time and temperature. (author)

  7. 2012 edition JMBR - CORRECTION.cdr

    African Journals Online (AJOL)

    FinePrint

    formaldehyde in the manufacture of plastics and also used as a flame retardant especially in buses and aircrafts. ... incidence of thousands of pet deaths in the. United States after consumption of imported pet food. Symptoms associated with melamine consumption included anorexia, vomiting, lethargy, polyuria and.

  8. Effect of resin variables on the creep behavior of high density hardwood composite panels

    Science.gov (United States)

    R.C. Tang; Jianhua Pu; C.Y Hse

    1993-01-01

    The flexural creep behavior of oriented strandboards (OSB) fabricated with mixed high, density hardwood flakes was investigated. Three types of adhesives, liquid phenolic-formaldehyde (LPF), melamine modified urea-formaldehyde (MUF), and LPF (face)/MUF (core) were chosen in this investigation. The resin contents (RC) used were 3.5 percent and 5.0 percent. The flakes...

  9. Preparation of CN /Carbon Nanotube Intramolecular Junctions by ...

    African Journals Online (AJOL)

    NICO

    middle during the growth process of the tubes. The phenomenon has been observed previously in preparing CNx/C intra- molecular junctions via the CVD method by pyrolysis of ferrocene and melamine.23 It should be pointed out that no catalyst is necessary for connecting CNx and MWCNT segments. As shown in Figs.

  10. Fascinating Organic Transformations

    Indian Academy of Sciences (India)

    cyanuric acid and melamine, with complementary hydrogen bonding sites arrange themselves in a beautiful architecture. In Figure 3, the a-helix is characterised by a sequence of parallel hydrogen bonds within the molecule along the helix axis. Other variations are possible, e.g., by mixing parallel and antiparallel.

  11. Nanostructured coatings for super hydrophobic textiles

    Indian Academy of Sciences (India)

    Nuva HPU, a fluorocarbon based finish (perfluo- roalkyl acrylic copolymerisate emulsion) from Clariant India. Ltd. was used as surface energy lowering agent while non- fluorocarbon based surface energy lowering agents like Cerol emulsion (a dispersion of melamine and paraffin wax) was procured from Clariant India Ltd.

  12. Browse Title Index

    African Journals Online (AJOL)

    Items 51 - 100 of 142 ... Vol 2 (1997), Physico-chemical studies of the adsorption of urea and melamine on sawdust, Abstract PDF. BT Nwufo, EN Okafo. Vol 6 (2001), Phytochemical analysis and antimicrobial activity screening of the crude extracts from the aerial parts of Tapinanthus globiferus Linn, Abstract PDF. IG Ndukwe ...

  13. Author Details

    African Journals Online (AJOL)

    Ayeni, N. Vol 1, No 1 (2010) - Articles A study of the kinetic of synthesis and crosslinking of methylol melamine. Abstract PDF. ISSN: 2384-6028. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

  14. 1, 3, 5-Triazine-2, 4, 6-triyltrisulfamic acid (TTSA): A new organic ...

    Indian Academy of Sciences (India)

    Melamine reacted with chlorosufonic acid (ClSO3H) to form a new sulfamic-type acid, 1,3,5-triazine-2,4,6-triyltrisulfamic acid (TTSA). Both nitrosation of secondary amines and oxidation of urazoles were accomplished by using TTSA/NaNO2 system under mild and heterogeneous conditions with good to excellent yields.

  15. 147-IJBCS-Article-Dr Osemeahon

    African Journals Online (AJOL)

    RHUMSIKI

    FTIR studies of the curing reactions of palm oil alkyd- melamine enamels. J. Appl. Polym. Sci.,. 80: 2309 – 2315. Gooch JW. 1997. Analytical and. Deformulation of Polymeric Materials: Paints, Plastics, Adhesives and Ink. Kluwer Academic Publichers: New York,. U. S. A; 119-120. Johnson BM, Wilkes GL. 2001. Microporous.

  16. Author Details

    African Journals Online (AJOL)

    Ibhazehiebo, K. Vol 7, No 1-2 (2008) - Articles Impact of noise on hearing amongst commercial motor bike riders in Benin- City, Nigeria. Abstract PDF · Vol 11, No 1 (2012) - Articles Melamine: An Emerging Neurotoxicant? Abstract PDF. ISSN: 1596-6941. AJOL African Journals Online. HOW TO USE AJOL... for Researchers ...

  17. Laser machining wood composites

    Science.gov (United States)

    Vladimir Barnekov; Henry A. Huber; Charles W. McMillin

    1989-01-01

    This practical, nonstatistical experiment using commercial equipment demonstrated that nominal 3/4-inch compositep anelsf or furniture consisting of a particleboard core,h igh density melamine crossbands, and walnut veneer face plies can be cut with a carbon dioxide/airjet-assisted laser to produce surfaces with minimal nonparallelism and char compared to previous...

  18. Nanopillar Filters for Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Durucan, Onur; Rindzevicius, Tomas; Schmidt, Michael Stenbæk

    2017-01-01

    We present a simple, robust, and automated molecule extraction technique based on a centrifugal microfluidic platform. Fast and facile extraction of a food adulterant (melamine) from a complex sample medium (milk) on a SERS substrate is demonstrated. The unique characteristic of the detection...

  19. Effect of different catalysts on urea-formaldehyde resin synthesis

    Science.gov (United States)

    Qi-Ning Sun; Chung-Yun Hse; Todd F. Shupe

    2014-01-01

    Four catalysts (H2SO4, HCl, H3PO4, and NaOH/NH4OH) were studied in the preparation of melamine modified urea– formaldehyde (UFM) resins. 13C-nuclear magnetic resonance spectroscopic analysis of the UFM resins at different synthesis stages revealed the...

  20. Synthesis of boron nitride from boron containing poly(vinyl alcohol ...

    Indian Academy of Sciences (India)

    acid or borax, and a nitrogen-containing compound such as melamine, urea or dicyandiamide are heated in an atmo- sphere of non-oxidizing gas such as nitrogen or ammonia. ∗. Author for correspondence (mitun@cgcri.res.in). These h-BN powders have low crystallinity and crystal- lographically it belongs to boron nitride ...

  1. Fe3C-based oxygen reduction catalysts: synthesis, hollow spherical structures and applications in fuel cells

    DEFF Research Database (Denmark)

    Hu, Yang; Jensen, Jens Oluf; Zhang, Wei

    2015-01-01

    We present a detailed study of a novel Fe3C-based spherical catalyst with respect to synthetic parameters, nanostructure formation, ORR active sites and fuel cell demonstration. The catalyst is synthesized by high temperature autoclave pyrolysis using decomposing precursors. Below 500 °C, melamine...

  2. Mechanochemical route to the synthesis of nanostructured Aluminium nitride

    Science.gov (United States)

    Rounaghi, S. A.; Eshghi, H.; Scudino, S.; Vyalikh, A.; Vanpoucke, D. E. P.; Gruner, W.; Oswald, S.; Kiani Rashid, A. R.; Samadi Khoshkhoo, M.; Scheler, U.; Eckert, J.

    2016-01-01

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN. PMID:27650956

  3. 1,3,5-Triazine-2,4,6-triyltrisulfamic acid (TTSA)

    Indian Academy of Sciences (India)

    Melamine reacted with chlorosufonic acid (ClSO3H) to form a new sulfamic-type acid, 1,3,5-triazine-2,4,6-triyltrisulfamic acid (TTSA). Both nitrosation of secondary amines and oxidation of urazoles were accomplished by using TTSA/NaNO2 system under mild and heterogeneous conditions with good to excellent yields.

  4. Detection and quantification of adulterants in milk powder using a high-throughput Raman chemical imaging technique.

    Science.gov (United States)

    Qin, Jianwei; Kim, Moon S; Chao, Kuanglin; Dhakal, Sagar; Lee, Hoonsoo; Cho, Byoung-Kwan; Mo, Changyeun

    2017-02-01

    Milk is a vulnerable target for economically motivated adulteration. In this study, a line-scan high-throughput Raman imaging system was used to authenticate milk powder. A 5 W 785 nm line laser (240 mm long and 1 mm wide) was used as a Raman excitation source. The system was used to acquire hyperspectral Raman images in a wave number range of 103-2881 cm - 1 from the skimmed milk powder mixed with two nitrogen-rich adulterants (i.e., melamine and urea) at eight concentrations (w/w) from 50 to 10,000 ppm. The powdered samples were put in sample holders with a surface area of 150 ×100 mm and a depth of 2 mm for push-broom image acquisition. Varying fluorescence signals from the milk powder were removed using a correction method based on adaptive iteratively reweighted penalised least squares. Image classifications were conducted using a simple thresholding method applied to single-band fluorescence-corrected images at unique Raman peaks selected for melamine (673 cm - 1 ) and urea (1009 cm - 1 ). Chemical images were generated by combining individual binary images of melamine and urea to visualise identification, spatial distribution and morphological features of the two adulterant particles in the milk powder. Limits of detection for both melamine and urea were estimated in the order of 50 ppm. High correlations were found between pixel concentrations (i.e., percentages of the adulterant pixels in the chemical images) and mass concentrations of melamine and urea, demonstrating the potential of the high-throughput Raman chemical imaging method for the detection and quantification of adulterants in the milk powder.

  5. Construction of g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} hybrids via in-situ acidification and exfoliation with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao-jing [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Liu, Chao [College of Gemmology and Material Technics, Hebei GEO University, Shijiazhuang 050031 (China); Li, Xu-li [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Li, Fa-tang, E-mail: lifatang@126.com [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Li, Yu-pei [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Zhao, Jun [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Liu, Rui-hong [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China)

    2017-02-01

    Highlights: • Ultrathin g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} hybrids are prepared via in-situ reaction. • The structure modification role of in-situ formed HNO{sub 3} for g-C{sub 3}N{sub 4} is found. • The ultrathin g-C{sub 3}N{sub 4} nanosheets are formed by the acidified melamine and Al(OH){sub 3}. • In-situ calcination of melamine and Al(OH){sub 3} benefits the contact of C{sub 3}N{sub 4} and Al{sub 2}O{sub 3}. • The activity of g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} is 16.6 times that of pristine g-C{sub 3}N{sub 4} in degrading RhB. - Abstract: Homogeneous ultrathin g-C{sub 3}N{sub 4} nanosheets/Al{sub 2}O{sub 3} heterojunctions are synthesized using melamine and Al(NO{sub 3}){sub 3} via in-situ reaction and the following thermal polymerization approach. The in-situ reaction between melamine and Al(NO{sub 3}){sub 3} results in the existence of HNO{sub 3}-acidified melamine and Al(OH){sub 3} aggregates via the hydrolysis of Al(NO{sub 3}){sub 3}. After thermal polymerization, the aggregates are converted to g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} composites. The thermal polymerization of acidified melamine and the support effect of aluminum hydroxide for g-C{sub 3}N{sub 4} during the calcination process lead to highly dispersed amrophous Al{sub 2}O{sub 3} on ultrathin g-C{sub 3}N{sub 4} nanosheets, which is beneficial for the separation of photogenerated electron-hole pairs in the heterojunction. The degradation rate for Rhodamine B (RhB) over the most activie sample is 16.6 times than that of pristine g-C{sub 3}N{sub 4} under visible light irradiation, which can be attributed to the high specific surface area, highly dispersion of amorphous Al{sub 2}O{sub 3} on ultrathin g-C{sub 3}N{sub 4} nanosheet, and the effective electrons transfer from g-C{sub 3}N{sub 4} to the amorphous Al{sub 2}O{sub 3}.

  6. Hard template synthesis of porous carbon nitride materials with improved efficiency for photocatalytic CO{sub 2} utilization

    Energy Technology Data Exchange (ETDEWEB)

    Ovcharov, M. [L.V Pysarzhevsky Institute of Physical Chemistry, NAS of Ukraine, 31 pr. Nauky, 03028 Kyiv (Ukraine); Shcherban, N., E-mail: nataliyalisenko@ukr.net [L.V Pysarzhevsky Institute of Physical Chemistry, NAS of Ukraine, 31 pr. Nauky, 03028 Kyiv (Ukraine); Filonenko, S.; Mishura, A. [L.V Pysarzhevsky Institute of Physical Chemistry, NAS of Ukraine, 31 pr. Nauky, 03028 Kyiv (Ukraine); Skoryk, M. [NanoMedTech LLC, 68 Gorkogo str., Kyiv (Ukraine); Shvalagin, V.; Granchak, V. [L.V Pysarzhevsky Institute of Physical Chemistry, NAS of Ukraine, 31 pr. Nauky, 03028 Kyiv (Ukraine)

    2015-12-15

    Graphical abstract: - Highlights: • Porous carbon nitrides were obtained via bulk and matrix pyrolysis of melamine. • Carbon nitride obtained in MCF has the highest bandgap and photocatalytic activity. • Acetaldehyde was the major product of the photoreduction reaction of CO2. - Abstract: Porous carbon nitrides of different morphology were obtained via bulk and hard template (SBA-15 and MCF) pyrolysis of melamine. Matrix method allowed obtaining ordered porous C{sub 3}N{sub 4} with higher bandgap (2.87 eV) in the contrary to the bulk sample (2.45 eV). Obtained carbon nitrides were found to be p-type semiconductors with catalytic activity towards photoreduction of carbon dioxide with water vapour. Carbon nitride obtained in MCF has the higher bandgap, developed surface, sponge-like morphology, spatially ordering and it's characterized by the highest photocatalytic activity.

  7. Chemical functionalization and stabilization of type I collagen with organic tanning agents

    Energy Technology Data Exchange (ETDEWEB)

    Albu, Madalina Georgiana; Deselnicu, Viorica; Ioannidis, Ioannis; Deselnicu, Dana; Chelaru, Ciprian [Leather and Footwear Research Institute, Bucharest (Romania)

    2015-02-15

    We investigated the interactions between selected organic tanning agents and type I fibrillar collagen as a model fibrillar substrate to enable the fast direct evaluation and validation of interpretations of tanning activity. Type I fibrillar collagen (1%) as gel was used as substrate of tanning and tannic acid, resorcinol- and melamine-formaldehyde and their combination at three concentrations as crosslinking agents (tannins). To evaluate the stability of collagen during tanning, the crosslinked gels at 2.8, 4.5 and 9.0 pHs were freeze-dried as discs which were characterized by FTIR, shrinkage temperature, enzymatic degradation and optical microscopy, and the results were validated by statistical analyses. The best stability was given by combinations between resorcinol- and melamine-formaldehyde at isoelectric pH.

  8. Effect of processing temperature on structure and photocatalytic properties of g-C{sub 3}N{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Papailias, I. [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, P.O. Box 60037, 153 10 Ag. Paraskevi, Attiki (Greece); Department of Chemical Engineering, National Technical University of Athens, P.O. Box 15780, Athens (Greece); Giannakopoulou, T.; Todorova, N. [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, P.O. Box 60037, 153 10 Ag. Paraskevi, Attiki (Greece); Demotikali, D. [Department of Chemical Engineering, National Technical University of Athens, P.O. Box 15780, Athens (Greece); Vaimakis, T. [Department of Chemistry, University of Ioannina, P.O. Box 1186, Ioannina (Greece); Trapalis, C., E-mail: trapalis@ims.demokritos.gr [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, P.O. Box 60037, 153 10 Ag. Paraskevi, Attiki (Greece)

    2015-12-15

    Graphical abstract: - Highlights: • g-C{sub 3}N{sub 4} photocatalysts were synthesized by thermal polycondensation of melamine. • The materials showed significant differences in structure and optical properties. • The best photocatalytic activity was exhibited by the sample prepared at 450 °C. - Abstract: Graphitic carbon nitride (g-C{sub 3}N{sub 4}) photocatalysts were synthesized by thermal polycondensation of melamine at different temperatures (450 °C, 550 °C and 650 °C). The crystalline structure, morphology, porosity, composition and light absorption of the materials were thoroughly investigated. Furthermore, their photocatalytic activity was evaluated by NO oxidation under UV and visible light irradiation. The results showed that the structural and optical properties highly depend on the process temperature and thus the degree of polycondensation. The best photocatalytic activity was exhibited by the sample prepared at 450 °C and the possible reasons were discussed.

  9. EFFECT OF DELAYING ADDITION TIME OF SMF SUPERPLASTICIZER ON HYDRATION CHARACTERISTICS OF BLENDED CEMENT PASTES

    Directory of Open Access Journals (Sweden)

    H. EL-DIDAMONY

    2012-09-01

    Full Text Available This paper aims to study the effect of delaying addition time of sulphonate melamine formaldehyde superplasticizer (SMF on the rheology and hydration characteristic of blended cement pastes up to 90 days. The optimum dosage of superplasticizer was chosen as 1.0 mass %, this dosage gives the higher compressive strength and bulk density as well as lower total porosity. The optimum delaying time of superplasticizer was 7.5 min which gives the highest fluidity, bulk density, compressive strength and chemically combined water contents of cement pastes, whereas, the delaying addition time of 15.0 min shows the lower values of bulk density, compressive strength and combined water contents. This is attributed to the reduction of hydration rate of cement, due to the formation of a polymer film around the cement particles and/or hydrated products. The superplasticizing effect improved with a delayed sulphonate melamine formaldehyde superplasticizer addition time.

  10. Preparation of boron nitride fiber by organic precursor method

    Directory of Open Access Journals (Sweden)

    Yingying Zhou

    Full Text Available In this paper, boron nitride polymer precursor was made by boric acid, melamine, twelve sodium alkyl sulfate as raw materials and pure water as medium which is heated to 70 °C. Boron nitride precursor polymer was soluble in formic acid solution. The boron nitride precursor can be electrostatically spun at the voltage in 23 kV and the distance between the positive and negative poles is 15 cm. The formed fiber is very uniform. The properties of the precursors were analyzed through electron microscope, infrared spectrum, X-ray and ultraviolet spectrum. The aim of the job is to got the precursor of BN and spun it. Keywords: Melamine, Boric acid, Boron nitride precursor, Electrostatic spinning

  11. 3-Nitrophenol–1,3,5-triazine-2,4,6-triamine (2/1

    Directory of Open Access Journals (Sweden)

    V. Sangeetha

    2013-06-01

    Full Text Available The asymmetric unit of the title compound, C3H6N6·2C6H5NO3, contains one melamine and two 3-nitrophenol molecules. The mean planes of the 3-nitrophenol molecules are almost orthogonal to the plane of melamine, making dihedral angles of 82.77 (4 and 88.36 (5°. In the crystal, molecules are linked via O—H...N, N—H...N and N—H...O hydrogen bonds, forming a three-dimensional network. The crystal also features weak C—H...π and π–π interactions [centroid–centroid distance = 3.9823 (9 Å].

  12. Intramolecular epistasis and the evolution of a new enzymatic function.

    Directory of Open Access Journals (Sweden)

    Sajid Noor

    Full Text Available Atrazine chlorohydrolase (AtzA and its close relative melamine deaminase (TriA differ by just nine amino acid substitutions but have distinct catalytic activities. Together, they offer an informative model system to study the molecular processes that underpin the emergence of new enzymatic function. Here we have constructed the potential evolutionary trajectories between AtzA and TriA, and characterized the catalytic activities and biophysical properties of the intermediates along those trajectories. The order in which the nine amino acid substitutions that separate the enzymes could be introduced to either enzyme, while maintaining significant catalytic activity, was dictated by epistatic interactions, principally between three amino acids within the active site: namely, S331C, N328D and F84L. The mechanistic basis for the epistatic relationships is consistent with a model for the catalytic mechanisms in which protonation is required for hydrolysis of melamine, but not atrazine.

  13. Formation of Sodium cyclo-Triphosphate by the Thermal Reaction of Sodium Dihydrogenphosphate-Organic Nitrogen Compound Mixtures; Rinsan nisuiso natoriumu-yuki chisso kagobutsu kongokei no kanetsu ni yoru cyclo-sanrinsan natoriumu no seisei

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Atsushi.; Kikui, Satoshi. [Yonago National College of Technology, Tottori (Japan). Department of Materials Science; Motooka, Itaru.; Nariai, Hiroyuki. [Kobe University, Hyogo (Japan). Department of Chemical Science and Engineering

    1998-11-10

    Mixtures of sodium dihydrogenphosphate (NaH{sub 2}PO{sub 4}) with biuret, cyanuric acid, or melamine were heated in a stream of nitrogen gas. Crystalline sodium polyphosphate of high-temperature type of Maddrell`s salt was produced at above 300 degree C in the NaH{sub 2}PO{sub 4}-cyanuric acid or NaH{sub 2}PO{sub 4}-melamine mixtures. Sodium cyclo-trihosphate was produced in the NaH{sub 2}PO{sub 3}-biuret mixture in a similar manner to the thermal reaction of NaH{sub 2}PO{sub 4}-urea mixture reported previously, which was considered to be responsible for the enhanced water-vapor pressure in samples caused by the the formation of a kind of (shell.) An increase in amount of biuret added was available for the formation of cyclo-triphosphate. (author)

  14. Formation of Sodium cyclo-Triphosphate by the Thermal Reaction of Sodium Dihydrogenphosphate-Organic Nitrogen Compound Mixtures. Rinsan nisuiso natoriumu-yuki chisso kagobutsu kongokei no kanetsu ni yoru cyclo-sanrinsan natoriumu no seisei

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Atsushi.; Kikui, Satoshi. (Yonago National College of Technology, Tottori (Japan). Department of Materials Science); Motooka, Itaru.; Nariai, Hiroyuki. (Kobe University, Hyogo (Japan). Department of Chemical Science and Engineering)

    1998-11-10

    Mixtures of sodium dihydrogenphosphate (NaH[sub 2]PO[sub 4]) with biuret, cyanuric acid, or melamine were heated in a stream of nitrogen gas. Crystalline sodium polyphosphate of high-temperature type of Maddrell's salt was produced at above 300 degree C in the NaH[sub 2]PO[sub 4]-cyanuric acid or NaH[sub 2]PO[sub 4]-melamine mixtures. Sodium cyclo-trihosphate was produced in the NaH[sub 2]PO[sub 3]-biuret mixture in a similar manner to the thermal reaction of NaH[sub 2]PO[sub 4]-urea mixture reported previously, which was considered to be responsible for the enhanced water-vapor pressure in samples caused by the the formation of a kind of (shell.) An increase in amount of biuret added was available for the formation of cyclo-triphosphate. (author)

  15. Radiation processing of polymer emulsion, 7

    International Nuclear Information System (INIS)

    Makuuchi, Keizo; Takagi, Toru; Nakayama, Hiroyuki.

    1983-01-01

    The film properties of thermosettable emulsions prepared by radiation method and persulfate method with same monomer composition were compared to make clear the features of the radiation-induced emulsion polymerization. The radiation method was superior to the persulfate method in the physical and chemical properties of the cured films. However, the surface gloss of the pigmented films from the radiation method were inferior to those from the persulfate method. The reason for the low surface gloss was investigated. The reaction products of glass which was used as reaction vessel with monomers were found to decrease the gloss. With ESCA (Electron Spectroscopy for Chemical Analysis) of the pigmented film it was found that there were much amount of isolated melamine resins in the radiation emulsion film than in the persufate emulsion film. The isolated melamine resins on the film surface caused by poor mutual solubility of the emulsion was found to decrease the surface gloss. (author)

  16. Metabolic engineering of microbial competitive advantage for industrial fermentation processes.

    Science.gov (United States)

    Shaw, A Joe; Lam, Felix H; Hamilton, Maureen; Consiglio, Andrew; MacEwen, Kyle; Brevnova, Elena E; Greenhagen, Emily; LaTouf, W Greg; South, Colin R; van Dijken, Hans; Stephanopoulos, Gregory

    2016-08-05

    Microbial contamination is an obstacle to widespread production of advanced biofuels and chemicals. Current practices such as process sterilization or antibiotic dosage carry excess costs or encourage the development of antibiotic resistance. We engineered Escherichia coli to assimilate melamine, a xenobiotic compound containing nitrogen. After adaptive laboratory evolution to improve pathway efficiency, the engineered strain rapidly outcompeted a control strain when melamine was supplied as the nitrogen source. We additionally engineered the yeasts Saccharomyces cerevisiae and Yarrowia lipolytica to assimilate nitrogen from cyanamide and phosphorus from potassium phosphite, and they outcompeted contaminating strains in several low-cost feedstocks. Supplying essential growth nutrients through xenobiotic or ecologically rare chemicals provides microbial competitive advantage with minimal external risks, given that engineered biocatalysts only have improved fitness within the customized fermentation environment. Copyright © 2016, American Association for the Advancement of Science.

  17. EPR Investigations of G-C3N4/TiO2 Nanocomposites

    Directory of Open Access Journals (Sweden)

    Dana Dvoranová

    2018-01-01

    Full Text Available The g-C3N4/TiO2 nanopowders prepared by the annealing of melamine and TiO2 P25 at 550 °C were investigated under dark and upon UV or visible-light photoactivation using X- and Q-band electron paramagnetic resonance (EPR spectroscopy. The EPR spectra of powders monitored at room temperature and 100 K showed the impact of the initial loading ratio of melamine/TiO2 on the character of paramagnetic centers observed. For the photocatalysts synthesized using a lower titania content, the paramagnetic signals characteristic for the g-C3N4/TiO2 nanocomposites were already found before exposure. The samples annealed using the higher TiO2 loading revealed the photoinduced generation of paramagnetic nitrogen bulk centers (g-tensor components g1 = 2.005, g2 = 2.004, g3 = 2.003 and hyperfine couplings from the nitrogen A1 = 0.23 mT, A2 = 0.44 mT, A3 = 3.23 mT typical for N-doped TiO2. The ability of photocatalysts to generate reactive oxygen species (ROS upon in situ UV or visible-light photoexcitation was tested in water or dimethyl sulfoxide by EPR spin trapping using 5,5-dimethyl 1-pyrroline N-oxide. The results obtained reflect the differences in photocatalyst nanostructures caused by the differing initial ratio of melamine/TiO2; the photocatalyst prepared by the high-temperature treatment of melamine/TiO2 wt. ratio of 1:3 revealed an adequate photoactivity in both spectral regions.

  18. RETARDANTY HOŘENÍ, JEJICH POUŽITÍ A VLIV NA ŽIVOTNÍ PROSTŘEDÍ

    OpenAIRE

    Petrová, Š. (Šárka); Soudek, P. (Petr); Vaněk, T. (Tomáš)

    2015-01-01

    Fire is a common cause of damage to people and property. The fires also cause a wide variety of acute and chronic pollution due to acid gases and persistent organic chemicals. Flame retardants are highly required chemicals that improve thermal resistance of materials. Main types of fire retardants used in polymers are phosphines, phosphonates, phosphates, silanes, siloxanes, boric acid, borates, carboranes, melamine derivatives, Al and Mg hydroxides as well as nanomaterials. Generally...

  19. Asphaltenes-based polymer nano-composites

    Science.gov (United States)

    Bowen, III, Daniel E

    2013-12-17

    Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

  20. Full recovery of Arundo donax particleboard from swelling test without waterproofing additives

    OpenAIRE

    Jose-Antonio Flores-Yepes; Jose-Joaquin Pastor-Perez; Francisco-Javier Gimeno-Blanes; Isabel Rodriguez-Guisado; María-José Frutos-Fernandez

    2012-01-01

    This paper presents the development of particleboard based on common reed, reproducing the industry standard manufacturing process applied to wood chipboard. One of the main properties of the resulting board was its resistance to water, due to the hydrophobic properties of the common reed, despite there being no incorporation of melamine or any other waterproofing additive. The boards that were developed were analyzed using 2 mm and 4 mm sieves for fibre selection, a manufacturing pressure of...

  1. Direct detection of additives and degradation products from polymers by liquid extraction surface analysis employing chip-based nanospray mass spectrometry.

    Science.gov (United States)

    Paine, Martin R L; Barker, Philip J; Maclauglin, Shane A; Mitchell, Todd W; Blanksby, Stephen J

    2012-02-29

    Polymer-based surface coatings in outdoor applications experience accelerated degradation due to exposure to solar radiation, oxygen and atmospheric pollutants. These deleterious agents cause undesirable changes to the aesthetic and mechanical properties of the polymer, reducing its lifetime. The use of antioxidants such as hindered amine light stabilisers (HALS) retards these degradative processes; however, mechanisms for HALS action and polymer degradation are poorly understood. Detection of the HALS TINUVIN®123 (bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate) and the polymer degradation products directly from a polyester-based coil coating was achieved by liquid extraction surface analysis (LESA) coupled to a triple quadrupole QTRAP® 5500 mass spectrometer. The detection of TINUVIN®123 and melamine was confirmed by the characteristic fragmentation pattern observed in LESA-MS/MS spectra that was identical to that reported for authentic samples. Analysis of an unstabilised coil coating by LESA-MS after exposure to 4 years of outdoor field testing revealed the presence of melamine (1,3,5-triazine-2,4,6-triamine) as a polymer degradation product at elevated levels. Changes to the physical appearance of the coil coating, including powder-like deposits on the coating's surface, were observed to coincide with melamine deposits and are indicative of the phenomenon known as polymer 'blooming'. For the first time, in situ detection of analytes from a thermoset polymer coating was accomplished without any sample preparation, providing advantages over traditional extraction-analysis approaches and some contemporary ambient MS methods. Detection of HALS and polymer degradation products such as melamine provides insight into the mechanisms by which degradation occurs and suggests LESA-MS is a powerful new tool for polymer analysis. Copyright © 2012 John Wiley & Sons, Ltd.

  2. Preceedings of the International Congress (12th), Corrosion Control for Low-Cost Reliability, Held in Houston, Texas on September 19 -24, 1993. Volume 2. Process Industries Plant Operations.

    Science.gov (United States)

    1993-09-24

    ammonium carbamate from two melamine plants was feared to cause variations in the redox potential of the urea synthesis solution. Such variations may...substantially increased, it was feared that the redox potential might diminish so much as to allow corrosion, especially of UNS S31603, to develop...the water are virtually zero. No traces of slime have been found. Pyrophosphate is injected into the SW System In the Water Treatment Building and has

  3. g-C{sub 3}N{sub 4} Modified biochar as an adsorptive and photocatalytic material for decontamination of aqueous organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Pi, Liu, E-mail: 626956077@qq.com; Jiang, Rui, E-mail: jumrychem@163.com; Zhou, Wangchi, E-mail: 931860337@qq.com; Zhu, Hua, E-mail: zhuhua333@126.com; Xiao, Wei, E-mail: gabrielxiao@whu.edu.cn; Wang, Dihua, E-mail: wangdh@whu.edu.cn; Mao, Xuhui, E-mail: clab@whu.edu.cn

    2015-12-15

    Graphical abstract: - Highlights: • Composite material consisting of photo-responsive C{sub 3}N{sub 4} and biochar was studied. • Interconnection of C{sub 3}N{sub 4} and biochar was fulfilled via a condensation reaction. • The adsorption properties of composite were governed by the biochar. • The composite exhibited decontamination capability even after saturated. • Adsorption and photo-induced regeneration were mutual beneficial in composite. - Abstract: Converting the waste biomasses with high-carbon content into value-added materials is an environmental-friendly way for their utilization. In this study, a leaf-derived biochar is modified with graphitic C{sub 3}N{sub 4} to fulfill an affordable composite material capable of removing organic pollutants via adsorptive and photocatalytic processes simultaneously. The preparation process includes a carbonization process of chestnut leaf biomass and a followed condensation reaction of melamine at 520 °C. The characterization shows that biochar and C{sub 3}N{sub 4} existed in the composites in their pristine status, and the effective connection of C{sub 3}N{sub 4} and biochar was established. The adsorptive performance of the composites is governed by the biochar content in the composite, thus showing favorable performance for the removal of cationic dye methylene blue (MB). The condensation reaction of the melamine precursor has a coalescing effect on the dispersed biochar, resulting in the growth of particle size of composite. The composites prepared at different biochar/melamine ratios all show a photocatalytic activity on decolorization of MB. In terms of the specific photocatalytic activity of C{sub 3}N{sub 4} in the composite, biochar/melamine ratio of 0.5:1 is the best. Unlike the conventional adsorptive carbon materials which have saturated adsorption capacity, the composite in this study retain a sustaining decontamination capability due to the photocatalytic degradation of adsorbed organic

  4. Single- and Multiwalled Carbon Nanotubes with Phosphorus Based Flame Retardants for Textiles

    OpenAIRE

    D. Wesolek; W. Gieparda

    2014-01-01

    Due to growing popularity of composites, modification methods to obtain the best properties are searched for. The aim of the study is to reduce the flammability of textile materials using nanocomposite polymer back-coating. Different types of carbon nanotubes (single- and multiwalled) and different phosphorus flame retardants (ammonium polyphosphates and melamine polyphosphate) were introduced into the resin and then the fabrics were covered by the obtained composites. Homogeneous dispersion ...

  5. Zusammensetzung für einen schwer entflammbaren Kunstharzschaum, sowie Verfahren zu dessen Herstellung

    OpenAIRE

    Menke, Klaus; Gettwert, Volker; Fischer, S.

    2012-01-01

    The invention relates to a composition for a synthetic resin foam of low flammability, comprising resin component (A), hardener component (B), and filler component (C), wherein the resin component (A) contains a phenolic resin or a mixture of phenolic resin and melamine resin, the hardener component (B) contains a reaction product of an organic nitrogen base and a polyol phosphoric acid ester, and the filler component (C) contains finely ground inorganic fillers. The invention further relates...

  6. Penetration Depth Measurement of Near-Infrared Hyperspectral Imaging Light for Milk Powder.

    Science.gov (United States)

    Huang, Min; Kim, Moon S; Chao, Kuanglin; Qin, Jianwei; Mo, Changyeun; Esquerre, Carlos; Delwiche, Stephen; Zhu, Qibing

    2016-03-25

    The increasingly common application of the near-infrared (NIR) hyperspectral imaging technique to the analysis of food powders has led to the need for optical characterization of samples. This study was aimed at exploring the feasibility of quantifying penetration depth of NIR hyperspectral imaging light for milk powder. Hyperspectral NIR reflectance images were collected for eight different milk powder products that included five brands of non-fat milk powder and three brands of whole milk powder. For each milk powder, five different powder depths ranging from 1 mm-5 mm were prepared on the top of a base layer of melamine, to test spectral-based detection of the melamine through the milk. A relationship was established between the NIR reflectance spectra (937.5-1653.7 nm) and the penetration depth was investigated by means of the partial least squares-discriminant analysis (PLS-DA) technique to classify pixels as being milk-only or a mixture of milk and melamine. With increasing milk depth, classification model accuracy was gradually decreased. The results from the 1-mm, 2-mm and 3-mm models showed that the average classification accuracy of the validation set for milk-melamine samples was reduced from 99.86% down to 94.93% as the milk depth increased from 1 mm-3 mm. As the milk depth increased to 4 mm and 5 mm, model performance deteriorated further to accuracies as low as 81.83% and 58.26%, respectively. The results suggest that a 2-mm sample depth is recommended for the screening/evaluation of milk powders using an online NIR hyperspectral imaging system similar to that used in this study.

  7. Electron radiation curing of particle boards and fiber building boards impregnated with artificial resins

    Energy Technology Data Exchange (ETDEWEB)

    Schaudy, R.; Proksch, E. (Oesterreichisches Forschungszentrum Seibersdorf GmbH Inst. fuer Chemie)

    1980-06-01

    The hardening of wood particle boards and fiber building boards impregnated with artificial resins using a technical electron accelerator was examined. Suitable resin-monomer mixtures were selected by in-vitro-tests. A styrene-free unsaturated polyester resin and acrylic-modified melamine resins turned out be suitable, whereas other unsaturated polyesters and activators used for curing by gamma irradiation did not fit. The hardened boards showed markedly inceased hardness and reduced swelling, but only moderate weather resistance.

  8. Multifunctional glass fiber/polyamide composites with thermal energy storage/release capability

    OpenAIRE

    G. Fredi; A. Dorigato; A. Pegoretti

    2018-01-01

    Thermoplastic composite laminates with thermal energy storage (TES) capability were prepared by combining a glass fabric, a polyamide 12 (PA12) matrix and two different phase change materials (PCMs), i.e. a paraffinic wax microencapsulated in melamine-formaldehyde shells and a paraffin shape stabilized with carbon nanotubes. The melt flow index of the PA12/PCM blends decreased with the PCM concentration, especially in the systems with shape stabilized wax. Differential scanning calorimetry sh...

  9. Synthèse de microcapsules biosourcées pour des applications cosméto-textiles

    OpenAIRE

    Soares-Latour, Émilie-Marie,

    2012-01-01

    Textile industry has been using microcapsules for many years especially in the design of cosmeto-textiles. Microcapsules used for textile applications are often obtained by in situ polycondensation of formaldehyde and melamine. The crosslinked membrane ensures good thermal and mechanical properties, essential for treatment applied during microcapsules deposit and for their attachment onto textile. The residual presence of formaldehyde, classified as carcinogenic substance of level 3, is probl...

  10. Ru 4 ion in CeO 2 (Ce 0.95 Ru 0.05 O 2− ): A non-deactivating ...

    Indian Academy of Sciences (India)

    A new WGS catalyst, Ce1−RuO2− (0 ≤ ≤ 0.1) was prepared by hydrothermal method using melamine as a complexing agent. The Catalyst does not require any pre-treatment. Among the several compositions prepared and tested, Ce0.95Ru0.05O2− (5% Ru4+ ion substituted in CeO2) showed very high WGS ...

  11. Defense Scrap Yard Handbook

    Science.gov (United States)

    1985-06-01

    is therefore necessary to give increased attention applied to plastics such as polystyrenes, acrylics to the recovery and recycling of plastic scrap...34thermosetting" is an adjective position and the basic resin used. The major class- applied to plastics (such as melamine, phenoliL, es are:a. Acrylics ...alloy and dentures industrial/medical X-ray and Dental wire (platinum alloy) lithographic) Detonator fuses Photographic hypo solution Electronic tube

  12. Template-free synthesis of porous graphitic carbon nitride/carbon composite spheres for electrocatalytic oxygen reduction reaction.

    Science.gov (United States)

    Fu, Xiaorui; Hu, Xiaofei; Yan, Zhenhua; Lei, Kaixiang; Li, Fujun; Cheng, Fangyi; Chen, Jun

    2016-01-28

    Porous graphitic carbon nitride/carbon composite spheres were synthesized using melamine and cyanuric acid, and glucose as the carbon nitride and carbon precursor, respectively. The 3D hierarchical composites efficiently catalyzed the oxygen reduction reaction with an onset potential of 0.90 V and a kinetic current density of 23.92 mA cm(-2). These merit their promising applications in fuel cells and metal-air batteries.

  13. Repulsion forces of superplasticizers on ground granulated blast furnace slag in alkaline media, from AFM measurements to rheological properties

    OpenAIRE

    Palacios, M.; Bowen, P.; Kappl, M.; Butt, H. J.; Stuer, M.; Pecharromán, C.; Aschauer, U.; Puertas, F.

    2012-01-01

    The electrostatic and steric repulsion induced by different superplasticizers on ground granulated blast furnace slag in alkaline media have been studied. The superplasticizers were sulfonated naphthalene, sulfonated melamine, vinyl copolymer, and polycarboxylate- based admixtures. With these superplasticizers the slag suspensions had negative zeta potentials, ranging from -3 to -10 mV. For the first time the adsorbed layer thicknesses for superplasticizers on slag using colloidal probe atomi...

  14. A one-step carbonization route towards nitrogen-doped porous carbon hollow spheres with ultrahigh nitrogen content for CO 2 adsorption

    KAUST Repository

    Wang, Yu

    2015-01-01

    © The Royal Society of Chemistry 2015. Nitrogen doped porous carbon hollow spheres (N-PCHSs) with an ultrahigh nitrogen content of 15.9 wt% and a high surface area of 775 m2 g-1 were prepared using Melamine-formaldehyde nanospheres as hard templates and nitrogen sources. The N-PCHSs were completely characterized and were found to exhibit considerable CO2 adsorption performance (4.42 mmol g-1).

  15. Penetration Depth Measurement of Near-Infrared Hyperspectral Imaging Light for Milk Powder

    Directory of Open Access Journals (Sweden)

    Min Huang

    2016-03-01

    Full Text Available The increasingly common application of the near-infrared (NIR hyperspectral imaging technique to the analysis of food powders has led to the need for optical characterization of samples. This study was aimed at exploring the feasibility of quantifying penetration depth of NIR hyperspectral imaging light for milk powder. Hyperspectral NIR reflectance images were collected for eight different milk powder products that included five brands of non-fat milk powder and three brands of whole milk powder. For each milk powder, five different powder depths ranging from 1 mm–5 mm were prepared on the top of a base layer of melamine, to test spectral-based detection of the melamine through the milk. A relationship was established between the NIR reflectance spectra (937.5–1653.7 nm and the penetration depth was investigated by means of the partial least squares-discriminant analysis (PLS-DA technique to classify pixels as being milk-only or a mixture of milk and melamine. With increasing milk depth, classification model accuracy was gradually decreased. The results from the 1-mm, 2-mm and 3-mm models showed that the average classification accuracy of the validation set for milk-melamine samples was reduced from 99.86% down to 94.93% as the milk depth increased from 1 mm–3 mm. As the milk depth increased to 4 mm and 5 mm, model performance deteriorated further to accuracies as low as 81.83% and 58.26%, respectively. The results suggest that a 2-mm sample depth is recommended for the screening/evaluation of milk powders using an online NIR hyperspectral imaging system similar to that used in this study.

  16. Experiment of forced convection heat transfer using microencapsulated phase-change-material slurries

    International Nuclear Information System (INIS)

    Kubo, Shinji; Akino, Norio; Tanaka, Amane; Nagashima, Akira.

    1997-01-01

    The present study describes an experiment on forced convective heat transfer using a water slurry of Microencapsulated Phase-change-material. A normal paraffin hydrocarbon is microencapsulated by melamine resin, melting point of 28.1degC. The heat transfer coefficient and pressure drop in a circular tube were evaluated. The heat transfer coefficient using the slurry in case with and without phase change were compared to in case of using pure water. (author)

  17. Influence of Different Mixing Ratios of Adhesives for Wood Bondline Quality

    OpenAIRE

    Jan Vanerek; Anna Benesova; Pavel Rovnanik

    2012-01-01

    The research study was based on an evaluation of the ability of glued test samples to pass the criterion of sufficient bondline adhesion under the exposure conditions defined in EN 302- 1. Additionally, an infrared spectroscopic analysis of the evaluated adhesives (phenol-resorcinol-formaldehyde PRF and melamine-ureaformaldehyde MUF) with different mix ratios was carried out to evaluate the possible effects of a faulty technological process.

  18. The fabrication of nanochain structure of gold nanoparticles and its application in ractopamine sensing.

    Science.gov (United States)

    Duan, Jiahua; He, Dawei; Wang, Wenshuo; Liu, Yongchuan; Wu, Hongpeng; Wang, Yongsheng; Fu, Ming; Li, Shulei

    2013-10-15

    The illegal food additives including ractopamine and melamine throw a serious threat to human health. In this paper, the ractopamine and melamine were first used to form the nanochain structure of citrate-stabilized gold nanoparticles (AuNPs) with a convenient and inexpensive method. The fabricated nanochain structure consisting of several AuNPs was characterized by Scanning Electron Microscopy. A new longitudinal surface plasma resonance, which could be adjusted from visible to near infrared range, was observed in absorption spectra due to the aggregation of AuNPs. This could be well explained by Finite Different Time Domain algorithm theoretically. As confirmed by Fourier Transform Infrared Spectroscopy, the complex formed by hydrogen-bonding interaction between melamine and ractopamine could effectively promote the aggregation of AuNPs that was useful to develop the sensitivity and selectivity for the detection of ractopamine. Hence, the plasmonic coupling phenomenon of gold nanochain could be applied in bio-assay for ractopamine through the change of solution's color and optical absorption band with naked eye or absorption spectra. The linear range was broadened to (1.23 × 10(-7)M, 1.11 × 10(-6)M) and the limit of detection was extended to 4.10 × 10(-8)M (S/N=3). More importantly, this time-saving method will be promising in rapid and selective detection of β-agonist for clinical applications. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

  19. Synthesis of nitrogen-doped graphene via solid microwave method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Li, E-mail: zhangli379@sohu.com [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Ji, Bingcheng, E-mail: debbo.jee@outlook.com [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Wang, Kai [School of Electrical Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Song, Jinyan [School of Information Engineering, Dalian Ocean University, Dalian, Liaoning 116024 (China)

    2014-07-01

    Graphical abstract: - Highlights: • A direct solid microwave method is developed to prepare nitrogen-doped graphene. • The method consists of two steps, namely the functionalization and microwave irradiation. • Melamine can serve as not only functionalizing agent but also nitrogen source. - Abstract: In this paper, we propose a solid microwave-mediated method for scalable production of nitrogen-doped graphene sheets (NGS) using low-cost industrial material melamine as functionalizing agent and nitrogen source. The strong interaction of microwaves with graphene oxide has been fully utilized to generate in situ heating that induces the decompose melamine and nitrogen doping of graphene. The morphology, structure, and components of the as-produced nitrogen-doped graphene are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), pore-size distribution (PSD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The results show NGS can be successfully synthesized via this strategy.

  20. The Google news effect: did the tainted milk scandal in China temporarily impact newborn feeding patterns in a maternity hospital?

    Science.gov (United States)

    Seror, Jeremy; Amar, Audrey; Braz, Leslie; Rouzier, Roman

    2010-06-01

    Many factors influence a mother's decision to breastfeed. We investigated whether the melamine scandal involving infant formula influenced the decision to breastfeed. News of the melamine scandal was revealed in September 2008 and rapidly spread via the Internet. We illustrate that this scandal significantly and rapidly impacted the pattern of newborn feeding among Chinese women who delivered at a hospital in the eastern district of Paris. This area is home to one of the largest groups of Chinese people in France. The breastfeeding rate increased sharply in September 2008 from 14% to a peak of 31% (p = 0.014) before decreasing over a 6-month period at a rate slower than the diminishing media frenzy. The effect of the melamine news coverage on the Internet was temporary and strongly associated to ethnicity and language (p = 0.015, p = 0.004, respectively). Numerous patients utilize the Internet to access medical information, and these findings highlight the Internet's role in the healthcare equation.

  1. Mixtures of Olive Pomace with Different Nitrogen Sources for the Control of Meloidogyne spp. on Tomato

    Science.gov (United States)

    Rodríguez-Kábana, R.; Estaún, V.; Pinochet, J.; Marfá, O.

    1995-01-01

    The efficacy of mixtures of dry olive (Olea europea) pomace with biuret, guanidine, and melamine for control of root-knot nematodes (Meloidogyne spp.) on tomato (Lycopersicon esculentum) was studied in greenhouse experiments. Olive pomace (OP) applied pre-plant at 10 g/kg soil was phytotoxic. Mixtures of OP (10 g/kg soil) with biuret or guanidine at 200-300 mg/kg soil reduced or eliminated the phytotoxic effect, controlled root-knot nematodes, and increased soil esterase activity indicative of microbial activity. The addition of biuret or guanidine without OP to soil at rates <300 mg/kg soil did not control root-knot nematodes. Melamine applied at 100-400 mg/kg soil was phytotoxic as were mixtures of melamine with OP. Treatment of OP with anhydrous ammonia increased N content of the material. In another greenhouse experiment, NH₃-treated OP added to soil was not phytotoxic to tomato, suppressed root-knot nematodes, and increased soil esterase activity. Greenhouse and microplot experiments with OP plus chicken litter demonstrated the efficacy of these combination amendments to control root-knot nematodes and increase tomato yields in Meloidogyne-infested soil. PMID:19277325

  2. Mixtures of Olive Pomace with Different Nitrogen Sources for the Control of Meloidogyne spp. on Tomato.

    Science.gov (United States)

    Rodríguez-Kábana, R; Estaún, V; Pinochet, J; Marfá, O

    1995-12-01

    The efficacy of mixtures of dry olive (Olea europea) pomace with biuret, guanidine, and melamine for control of root-knot nematodes (Meloidogyne spp.) on tomato (Lycopersicon esculentum) was studied in greenhouse experiments. Olive pomace (OP) applied pre-plant at 10 g/kg soil was phytotoxic. Mixtures of OP (10 g/kg soil) with biuret or guanidine at 200-300 mg/kg soil reduced or eliminated the phytotoxic effect, controlled root-knot nematodes, and increased soil esterase activity indicative of microbial activity. The addition of biuret or guanidine without OP to soil at rates <300 mg/kg soil did not control root-knot nematodes. Melamine applied at 100-400 mg/kg soil was phytotoxic as were mixtures of melamine with OP. Treatment of OP with anhydrous ammonia increased N content of the material. In another greenhouse experiment, NH-treated OP added to soil was not phytotoxic to tomato, suppressed root-knot nematodes, and increased soil esterase activity. Greenhouse and microplot experiments with OP plus chicken litter demonstrated the efficacy of these combination amendments to control root-knot nematodes and increase tomato yields in Meloidogyne-infested soil.

  3. Plastination of macroparasites: An eco-friendly method of long-term preservation.

    Science.gov (United States)

    Kumar, Niranjan; Das, Bhupamani; Solanki, Jayesh B; Jadav, Mehul M; Menaka, Ramasamy

    2017-11-01

    Preservation of macroparasites by infiltrating the polymer in the tissues can defy the inherited shortcoming of classical wet preservation method. Preservation was done by infiltrating the melamine alone or with xylene (MX)/chloroform (MC)/turpentine oil (MT) in 1:1 and hardener (MH) in 9:1 ratio in the tissues of the gross specimen of the animal parasites. The plastinated models withstand the process of microbial decomposition, and remain intact in the environmental conditions. The polymer mixture resists the entry of the water molecule, and model dried just after taking out it from the water tank. Overall, the plastinated parasites were dry, non-sticky, glossy, odorless, chemical free, and harmless, to some extent flexible, with detectable morphological structure, and retain their natural form but lost their natural color. Full marks were assigned to the degree of dryness, non-stickiness, and odorlessness to the model plastinated in different solutions on a five-point scale. For flexibility, the score was 1.2, 2.2, and 2.4 for the plastinated model in melamine/MH, MX/MC, and MT solutions, respectively. The average score of glossiness was 4.6 and 5 for the specimen plastinated in melamine/MH and MX/MC/MT solutions, respectively. The degree of dryness, glossiness, stickiness, and flexibility varies non-significantly, with the polymer mixtures used. The prepared model can be used to educate the students/general mass population.

  4. Plastination of macroparasites: An eco-friendly method of long-term preservation

    Directory of Open Access Journals (Sweden)

    Niranjan Kumar

    2017-11-01

    Full Text Available Aim: Preservation of macroparasites by infiltrating the polymer in the tissues can defy the inherited shortcoming of classical wet preservation method. Materials and Methods: Preservation was done by infiltrating the melamine alone or with xylene (MX/chloroform (MC/turpentine oil (MT in 1:1 and hardener (MH in 9:1 ratio in the tissues of the gross specimen of the animal parasites. Results: The plastinated models withstand the process of microbial decomposition, and remain intact in the environmental conditions. The polymer mixture resists the entry of the water molecule, and model dried just after taking out it from the water tank. Overall, the plastinated parasites were dry, non-sticky, glossy, odorless, chemical free, and harmless, to some extent flexible, with detectable morphological structure, and retain their natural form but lost their natural color. Full marks were assigned to the degree of dryness, non-stickiness, and odorlessness to the model plastinated in different solutions on a five-point scale. For flexibility, the score was 1.2, 2.2, and 2.4 for the plastinated model in melamine/MH, MX/MC, and MT solutions, respectively. The average score of glossiness was 4.6 and 5 for the specimen plastinated in melamine/MH and MX/MC/MT solutions, respectively. The degree of dryness, glossiness, stickiness, and flexibility varies non-significantly, with the polymer mixtures used. Conclusion: The prepared model can be used to educate the students/general mass population.

  5. ANALISIS FAKTOR-FAKTOR YANG BERPENGARUH TERHADAP KINERJA BALAI BESAR PENGAWAS OBAT DAN MAKANAN DI YOGYAKARTA DALAM MENANGANI KASUS MAKANAN BERMELAMIN

    Directory of Open Access Journals (Sweden)

    Khusnul Diana

    2017-03-01

    Full Text Available Melamine is not prohibited chemical to mix into food product. Around 2008, Melamine had found in baby milk which was made by China to make high protein level. To see BBPOM Yogyakarta’s performance handling of food which has contaminated of melamine, it is needed evaluation from customer’s satisfaction and affection of monitoring food contaminated melamine’s factors. In addition, it is necessary to know the gap between expectation and society’s perception. The study is descriptive explorative research. The study has done by giving performance questionnaire and the factor that affect to performance of employee at Investigation and Inspection sector in BBPOM Yogyakarta and qualitative analysis has done by interview. Based on the analysis result, personal/human resources, monitored system and infrastructure factors has not significance effect to BBPOM Yogyakarta performance handling contaminated food, because the monitoring has limited for withdrawing and scrapping product. From the interview result is known that there is an effect between personal/human resources, monitored system and infrastructures factors, because it is influenced by theoretical and subjectivity of respondent.

  6. Facile synthesis high nitrogen-doped porous carbon nanosheet from pomelo peel and as catalyst support for nitrobenzene hydrogenation

    Science.gov (United States)

    Zuo, Pingping; Duan, Jiaqi; Fan, Huailin; Qu, Shijie; Shen, Wenzhong

    2018-03-01

    Nitrogen-doping porous carbon-based nanosheets were fabricated from pemole peel and melamine through hydrothermal route and carbonization. The pomelo peel with sponge-like natural structure was employed as carbon source, and melamine was used both as nitrogen precursors and as nanosheet structure directing. The morphology and chemical composition of the obtained porous carbon nanosheet carbon materials were characterized by scanning electron microscopy, thermogravimetric analyzer, Fourier transform infrared spectra, transmission electron microscopy, BET surface area measurement, X-ray photoelectron spectroscopy and X-ray powder diffraction. The result indicated that the nanosheet thickness, nitrogen-doped amount and surface area were determined by the ratio of pomelo peel to melamine and carbonization temperature. The catalytic nitrobenzene hydrogenation was evaluated after Pd was loaded on nitrogen-doping porous carbon-based nanosheet. The results showed Pd@PCN had almost 100% conversion and good cycling performance towards the hydrogenation of nitrobenzene due to the developed pore structure, high nitrogen-doping and well dispersed less Pd particle; it was superior to other nanomaterial supports and demonstrated great potential application.

  7. FORTALECIMIENTO DE LA CADENA PRODUCTIVA DEL BAMBÚ GUADUA CON LA PRODUCCIÓN DE LAMINADOS STRENGTHENING OF THE BAMBOO GUADUA CHAIN WITH PRODUCTION OF LAMINATES

    Directory of Open Access Journals (Sweden)

    Caori Patricia Takeuchi Tam

    2011-06-01

    Full Text Available Se presentan los procesos de corte del bambú guadua, la obtención de láminas, la fabricación de laminados y los resultados de ensayos en láminas y probetas laminadas elaboradas con cuatro tipos de pegantes: melamina, resorcinol, acetato de polivinilo y cola natural. Se encontró que la retracción longitudinal de las láminas es relativamente baja y la relación entre las retracciones tangencial y radial fue cercana a 1,0 mostrando la viabilidad del uso del bambú guadua para procesos de laminado. Se encontraron los siguientes valores de resistencia promedio: a corte paralelo 47 kg•cm-2 (melamina, 51 kg•cm-2 (resorcinol, 17 kg•cm-2 (PVA y 32 kg•cm-2 MPa (cola; a corte perpendicular 50 kg•cm-2 (melamina, 43 kg•cm-2 (resorcinol, 49 kg•cm-2 (PVA y 37 kg•cm-2 (cola; a tracción perpendicular 8,3 kg•cm-2 (melamina, 4,9 kg•cm-2 (resorcinol, 1,7 kg•cm-2 (PVA y 3,7 kg•cm-2 MPa (cola; a compresión paralela 419 kg•cm-2 (melamina, 424 kg•cm-2 (resorcinol, 506 kg•cm-2 (PVA y 375 kg•cm-2 (cola y a compresión perpendicular 216 kg•cm-2 (melamina, 206 kg•cm-2 (resorcinol, 245 kg•cm-2 (PVA y 240 kg•cm-2 (cola. Se observó que en general las probetas elaboradas con melamina y resorcinol presentaron un mejor comportamiento mecánico.In this paper, the process of cutting the bamboo guadua, the production of slats, the manufacture of laminates and results of tests in slats and laminated samples made with four types of glue: -melamine, resorcinol, polyvinyl acetate and natural glue are presented. It was found that the longitudinal shrinkage of the bamboo guadua slats is relatively low and the relationship between the tangential and radial shrinkage was close to one showing the feasibility of using bamboo for laminated processes. The following average values of resistance were found: for parallel shear 47 kg•cm-2 (melamine, 51 kg•cm-2 (resorcinol, 17 kg•cm-2 (PVA and 32 MPa kg•cm-2 (kola; for perpendicular shear

  8. Cobalt-doped graphitic carbon nitride photocatalysts with high activity for hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Pei-Wen; Li, Kui; Yu, Yu-Xiang; Zhang, Wei-De, E-mail: zhangwd@scut.edu.cn

    2017-01-15

    Graphical abstract: Cobalt-doped graphitic carbon nitride (Co−CN) was synthesized by one-step thermal polycondensation using cobalt phthalocyanine and melamine as precursors. The obtained photocatalysts display high and stable activity for photocatalytic generation of hydrogen through water splitting. - Highlights: • Cobalt-doped g-C{sub 3}N{sub 4} photocatalysts were prepared. • High and stable visible light photocatalytic activity for H{sub 2} evolution. • Efficient separation and transfer of photo-induced electron-hole pairs. - Abstract: Cobalt-doped graphitic carbon nitride (Co−CN) was synthesized by one-step thermal polycondensation using cobalt phthalocyanine (CoPc) and melamine as precursors. The π-π interaction between melamine and CoPc promotes cobalt doping into the framework of g-C{sub 3}N{sub 4}. The prepared samples were carefully characterized and the results demonstrated that Co-doped graphitic carbon nitride inhibited the crystal growth of graphitic carbon nitride (CN), leading to larger specific surface area (33.1 m{sup 2} g{sup −1}) and abundant Co-N{sub x} active sites, narrower band gap energy and more efficient separation of photogenerated electrons and holes. 0.46% Co−CN exhibited higher hydrogen evolution rate (28.0 μmol h{sup −1}) under visible light irradiation, which is about 3.0 times of that over the pure CN and about 2.2 times of that over cobalt-doped CN using CoCl{sub 2} ∙ 6H{sub 2}O as a cobalt source. This study provides a valuable strategy to modify CN with enhanced photocatalytic performance.

  9. Novel band gap-tunable K–Na co-doped graphitic carbon nitride prepared by molten salt method

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiannan [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China); School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun 113001 (China); Ma, Lin [School of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001 (China); Wang, Haoying; Zhao, Yanfeng [School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun 113001 (China); Zhang, Jian [School of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001 (China); Hu, Shaozheng, E-mail: hushaozhenglnpu@163.com [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China)

    2015-03-30

    Graphical abstract: K and Na ions co-doped into g-C{sub 3}N{sub 4} crystal lattice can tune the position of CB and VB potentials, influence the structural and optical properties, and thus improve the photocatalytic degradation and mineralization ability. - Highlights: • K, Na co-doped g-C{sub 3}N{sub 4} was prepared in KCl/NaCl molten salt system. • The structural and optical properties of g-C{sub 3}N{sub 4} were greatly influenced by co-doping. • The position of VB and CB can be tuned by controlling the weight ratio of eutectic salts to melamine. • Co-doped g-C{sub 3}N{sub 4} showed outstanding photodegradation ability, mineralization ability, and catalytic stability. - Abstract: Novel band gap-tunable K–Na co-doped graphitic carbon nitride was prepared by molten salt method using melamine, KCl, and NaCl as precursor. X-ray diffraction (XRD), N{sub 2} adsorption, Scanning electron microscope (SEM), UV–vis spectroscopy, Photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The CB and VB potentials of graphitic carbon nitride could be tuned from −1.09 and +1.55 eV to −0.29 and +2.25 eV by controlling the weight ratio of eutectic salts to melamine. Besides, ions doping inhibited the crystal growth of graphitic carbon nitride, enhanced the surface area, and increased the separation rate of photogenerated electrons and holes. The visible-light-driven Rhodamine B (RhB) photodegradation and mineralization performances were significantly improved after K–Na co-doping.

  10. Facile synthesis of nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiangpeng; Li, Changqing; Cong, Jingkun; Liu, Ziwei; Zhang, Hanzhuo; Liang, Mei [The Key laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab for Textile Fiber Materials and Processing Technology (Zhejiang), College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Gao, Junkuo, E-mail: jkgao@zstu.edu.cn [The Key laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab for Textile Fiber Materials and Processing Technology (Zhejiang), College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Wang, Shunli [Department of Physics, Center for Optoelectronic Materials and Devices, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Yao, Juming, E-mail: yaoj@zstu.edu.cn [The Key laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, National Engineering Lab for Textile Fiber Materials and Processing Technology (Zhejiang), College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2016-06-15

    Here we report a facile synthesis of nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite (Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4}) by using Fe-melamine supramolecular framework as precursor. The chemical and optical properties of the nanocomposites are well-characterized. The Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} nanocomposite demonstrated excellent photocatalytic activities under visible light due to the efficient utilization of sunlight and the construction of Z-scheme electron transfer pathway. The results indicated that it could be a promising approach for the preparation of efficient g-C{sub 3}N{sub 4} nanocomposites photocatalysts by using metal-melamine supramolecular framework as precursors. - Graphical abstract: Nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite (Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4}) was synthesized by using Fe-melamine supramolecular framework as precursor. The Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} nanocomposite demonstrated excellent photocatalytic activities under visible light. Display Omitted - Highlights: • Nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite (Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4}) was synthesized. • Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} showed strong optical absorption in the visible-light region. • The Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} nanocomposite demonstrated excellent photocatalytic activities.

  11. An investigation of FT-Raman spectroscopy for quantification of additives to milk

    Science.gov (United States)

    Cheng, Yuche; Qin, Jianwei; Lim, Jongguk; Chan, Diane E.; Kim, Moon S.; Chao, Kuanglin

    2012-05-01

    In this research, four chemicals, urea, ammonium sulfate, dicyandiamide, and melamine, were mixed into liquid nonfat milk at concentrations starting from 0.1% to a maximum concentration determined for each chemical according to its maximum solubility, and two Raman spectrometers-a commercial Nicolet Raman system and an in-house Raman Chemical Imaging (RCI) system-were used to acquire Raman shift spectra for these mixture samples. These chemicals are potential adulterants that could be used to artificially elevate protein measurements of milk products evaluated by the Kjeldahl method. Baseline subtraction was employed to eliminate milk intensity, and the normalized Raman intensity was calculated from the specific Raman shift from the spectrum of solid chemical. Linear relationships were found to exist between the normalized Raman intensity and chemical concentrations. The linear regression coefficients (R2) ranged from 0.9111 to 0.998. Although slightly higher R2 values were calculated for regressions using spectral intensities measured by the Nicolet system compared to those using measurements from the RCI system, the results from the two systems were similar and comparable. A very low concentration of melamine (400 ppm) in milk was also found to be detectable by both systems. Raman sensitivity of Nicolet Raman system was estimated from normalized Raman intensity and slope of regression line in this study. Chemicals (0.2%) were dissolved in milk and detected the normalized Raman intensity. Melamine was found to have the highest Raman sensitivity, with the highest values for normalized Raman intensity (0.09) and regression line slope (57.04).

  12. In situ construction of g-C3N4/TiO2 heterojunction films with enhanced photocatalytic activity over magnetic-driven rotating frame

    Science.gov (United States)

    Pan, Chao; Jia, Jia; Hu, Xiaoyun; Fan, Jun; Liu, Enzhou

    2018-02-01

    Corn-shaped TiO2 nanofilms were fabricated by a glycerol-assisted hydrothermal method, and then g-C3N4 was deposited on the surface of TiO2 films using melamine as precursor under air atmosphere by an in site microwave-heating technique. The investigations indicate that microwave-heating process is a facile strategy to obtain g-C3N4 by thermal polymerization of melamine, which can achieve in situ constructing of g-C3N4/TiO2 heterojunction films with high stability. The as-prepared TiO2 films with crack and holes have visible light scattering capability, and the scattering light overlaps with the intrinsic absorption of g-C3N4, leading to an absorption plateau in the range of 400-550 nm. Besides, a magnetic-driven rotating frame was developed to enhance the mass transfer processes during the photocatalytic water splitting. The result shows that g-C3N4/TiO2 films exhibit excellent activities under simulated-sunlight irradiation, in addition to the enhanced mass transfer, the overlapped visible light absorption, stable contact and effective charge transfer between g-C3N4 and TiO2 can facilitate the hydrogen production and light utilization efficiency as well. The hydrogen production rate can reach 13.8 mmol h-1 m-2 over g-C3N4/TiO2 films prepared using 0.5 g of melamine and 16.0 cm2 of TiO2.

  13. The Multiple Effects of Precursors on the Properties of Polymeric Carbon Nitride

    Directory of Open Access Journals (Sweden)

    Wendong Zhang

    2013-01-01

    Full Text Available Polymeric graphitic carbon nitride (g-C3N4 materials were prepared by direct pyrolysis of thiourea, dicyandiamide, melamine, and urea under the same conditions, respectively. In order to investigate the effects of precursors on the intrinsic physicochemical properties of g-C3N4, a variety of characterization tools were employed to analyze the samples. The photocatalytic activity of the samples was evaluated by the removal of NO in gas phase under visible light irradiation. The results showed that the as-prepared CN-T (from thiourea, CN-D (from dicyandiamide, CN-M (from melamine, and CN-U (from urea exhibited significantly different morphologies and microstructures. The band gaps of CN-T, CN-D, CN-M, and CN-U were 2.51, 2.58, 2.56, and 2.88 eV, respectively. Both thermal stability and yield are in the following order: CN-M > CN-D > CN-T > CN-U. The photoactivity of CN-U (31.9% is higher than that of CN-T (29.6%, CN-D (22.2%, and CN-M (26.8%. Considering the cost, toxicity, and yield of the precursors and the properties of g-C3N4, the best precursor for preparation of g-C3N4 was melamine. The present work could provide new insights into the selection of suitable precursor for g-C3N4 synthesis and in-depth understanding of the microstructure-dependent photocatalytic activity of g-C3N4.

  14. Process for preparing wastes for non-pollutant disposal

    International Nuclear Information System (INIS)

    Rosenstiel, T.L.; Debus, A.A.G.

    1984-01-01

    In disposing of wastes, particularly toxic wastes, containing organic liquids, i.e. solvents or oil, which may be radio-active a non-ionic surface active agent which is a polyoxy alkylphenol is added to the oily material and then calcium sulphate hemihydrate and water are added. This forms part of a process in which a melamine resin is also added to the mix which is then allowed to harden and the hardened mass disposed of. The use of polyoxyethylene glycol soaps as emulsifying agents is also referred to. Preferred soaps are tallates and preferred alkyl groups in the alkylphenol are octyl and ronyl. (author)

  15. “Rings of saturn-like” nanoarrays with high number density of hot spots for surface-enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Zhigao; Liao, Lei; Wu, Wei; Guo, Shishang; Zhao, Xinyue; Li, Wei; Ren, Feng; Jiang, Changzhong, E-mail: xxh@whu.edu.cn, E-mail: czjiang@whu.edu.cn [Department of Physics, Hubei Nuclear Solid Physics Key Laboratory and Center for Ion Beam Application, Wuhan University, Wuhan 430072 (China); Mei, Fei [Department of Physics, Hubei Nuclear Solid Physics Key Laboratory and Center for Ion Beam Application, Wuhan University, Wuhan 430072 (China); School of Electrical and Electronic Engineering, Hubei University of Technology, Wuhan 430068 (China); Xiao, Xiangheng, E-mail: xxh@whu.edu.cn, E-mail: czjiang@whu.edu.cn [Department of Physics, Hubei Nuclear Solid Physics Key Laboratory and Center for Ion Beam Application, Wuhan University, Wuhan 430072 (China); Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095 (United States); Fu, Lei; Wang, Jiao [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China)

    2014-07-21

    The Ag nanoparticles (NPs) surrounding triangular nanoarrays (TNAs) with high number density of surface-enhanced Raman scattering (SERS) hot spots (SERS hot spots ring) are prepared by a combination of NPs deposition and subsequent colloid lithography processing. Owing to the SERS hot spots ring, the Ag NPs surrounding TNAs have been proved an excellent candidate for ultrasensitive molecular sensing for their high SERS signal enhancing capacity in experiments and theories. The Ag NPs surrounding TNAs can be readily used for the quick detection of low concentrations of molecules related to food safety; herein, detection of melamine is discussed.

  16. Porous pcu-type Zn(II) framework material with high adsorption selectivity for CO2 over N2

    Science.gov (United States)

    Lu, Yiping; Dong, Yanli; Qin, Jing

    2016-03-01

    Reported here is a new Zn(II) compound, namely [Zn2(tdc)2(MA)]n (H2tdc = 2,5-thiophenedicarboxylic acid, MA = melamine), which has been constructed by the self-assembly reaction of Zn(NO3)2, H2tdc and MA under solvothermal conditions. Single crystal X-ray diffraction analysis reveals that this compound features a 3D porous framework with 6-connected pcu topology. Notably, this compound exhibits high CO2 sorption capacity and high sorption selectivity for CO2 over N2 at 298 K.

  17. Photoelectric method for determination of the relative radii of microparticles

    Science.gov (United States)

    Lapitsky, D. S.

    2018-01-01

    Experimental results of relative radii of microparticles determination by the analysis of scattered on particles radiation are presented. Due to the monotonous dependence of the indicatrix of particle scattered radiation on particle radius at a specific angle, it becomes possible to determine the relative radii of particles in cloud of particles by one camera picture. Radii of three types of monodisperse powders of melamine formaldehyde particles with known sizes were analyzed by means of Mie theory. The results showed the possibility to determine relative radii of particles to each other in suspended clouds of particles.

  18. Piperidine-based glycodendrons as protein N-glycan prosthetics.

    Science.gov (United States)

    Hudak, Jason E; Belardi, Brian; Appel, Mason J; Solania, Angelo; Robinson, Peter V; Bertozzi, Carolyn R

    2016-10-15

    The generation of homogeneously glycosylated proteins is essential for defining glycoform-specific activity and improving protein-based therapeutics. We present a novel glycodendron prosthetic which can be site-selectively appended to recombinant proteins to create 'N-glycosylated' glycoprotein mimics. Using computational modeling, we designed the dendrimer scaffold and protein attachment point to resemble the native N-glycan architecture. Three piperidine-melamine glycodendrimers were synthesized via a chemoenzymatic route and attached to human growth hormone and the F c region of human IgG. These products represent a new class of engineered biosimilars bearing novel glycodendrimer structures. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Determination of emerging nitrogenous economic adulterants in milk proteins by high-performance liquid chromatography/compact mass spectrometry.

    Science.gov (United States)

    Draher, Jonathan; Ehling, Stefan; Cellar, Nick; Reddy, Todime; Henion, Jack; Sousou, Nigel

    2016-06-15

    Milk-derived ingredients are widely used around the world in the manufacturing of nutritional products. They are prone to economically motivated adulteration with nitrogenous compounds such as melamine and its analogs in order to increase the nitrogen content of these ingredients. The need to rapidly screen milk-derived ingredients to detect adulteration is of paramount public health concern. A liquid chromatography/mass spectrometry (LC/MS)-based method using a single quadrupole mass spectrometer has been developed for the rapid frontline analysis of six nitrogenous protein adulterants, i.e. melamine, ammeline, ammelide, amidinourea, cyromazine and cyanuric acid, in three key milk-derived ingredients, i.e. whole milk powder, nonfat milk powder and whey protein concentrate. The sample preparation scheme involves both 'dilute and shoot' as well as solid-phase extraction (SPE)-based methods. The 'dilute and shoot' scheme uses a tenfold dilution of sample with water followed by protein precipitation using 2% formic acid in acetonitrile. The SPE scheme involves tenfold dilution of sample with water, followed by protein precipitation using acetonitrile, and further cleanup through Strata Melamine SPE cartridges. Sample extracts were analyzed by hydrophilic interaction chromatography/single quadrupole mass spectrometry (HILIC/MS) in both positive and negative electrospray ionization mode. Accurate quantitation was achieved using stable isotope labeled internal standards. A multi-day method validation study was conducted using three different milk-derived ingredients. Average accuracies, relative standard deviations (RSD) and method detection limits (MDL) for all analytes in whole milk powder were 65-118%, 7-11% and 0.9-30 mg/kg, using the 'dilute and shoot' extraction procedure. The SPE procedure results were 102-111%, 5-13%, and 0.4-2.5 mg/kg, respectively, for melamine, ammeline, ammelide and cyromazine only. A rugged and simple to use analytical method to screen for

  20. Photo-Curable Polymer Blend Dielectrics for Advancing Organic Field-Effect Transistor Applications

    Energy Technology Data Exchange (ETDEWEB)

    S Kim; K Hong; M Jang; J Jang; J Anthony; H Yang; C Park

    2011-12-31

    A solution method of photo-curable and -patternable polymer gate dielectrics was introduced by using blend solutions of poly(4-dimethylsilyl styrene) (PDMSS) and poly(melamine-co-formaldehyde) acrylate (PMFA). The fabrication was optimized to produce a smooth hydrophobic gate dielectric with good insulating and solvent-resistant properties. On the optimized PDMSS/PMFA blend gate dielectric, pentacene could grow into highly ordered structure, showing high electric performances for the resulting OFETs, as well as PTCDI-C13 and TES-ADT.

  1. Plastic

    International Nuclear Information System (INIS)

    Jeong Gi Hyeon

    1987-04-01

    This book deals with plastic, which includes introduction for plastic, chemistry of high polymers, polymerization, speciality and structure of a high molecule property of plastic, molding, thermosetting plastic, such as polyethylene, polyether, polyamide and polyvinyl acetyl, thermal plastic like phenolic resins, xylene resins, melamine resin, epoxy resin, alkyd resin and poly urethan resin, new plastic like ionomer and PPS resin, synthetic laminated tape and synthetic wood, mixed materials in plastic, reprocessing of waste plastic, polymer blend, test method for plastic materials and auxiliary materials of plastic.

  2. Survey on drum containers for radioactive wastes

    International Nuclear Information System (INIS)

    Kato, Kiyoshi; Tozawa, Seiichi; Maeda, Sho

    1981-01-01

    This report summarized the survey on drum containers for radioactive wastes which were used at nuclear power plants and research institutes in Japan, with respect to the specifications such as structure and coating system. The containers investigated are full removable head steel drums (200l) specified by JIS Z 1600 (1977). The drums made of steel sheets of 1.6mm thickness are most widely used in nuclear facilities. These conventional drums are coated with melamine-alkyd resin paints on the outside and epoxy resin paints on the inside, after the surface treatment with zinc phosphate. (author)

  3. Chemistry and Materials Science progress report, first half FY 1992

    International Nuclear Information System (INIS)

    1992-07-01

    This report contains sections on: Fundamentals of the physics and processing of metals; interfaces, adhesion, and bonding; energetic materials; plutonium research; synchrotron radiation-based materials science; atomistic approach to the interaction of surfaces with the environment: actinide studies; properties of carbon fibers; buried layer formation using ion implantation; active coherent control of chemical reaction dynamics; inorganic and organic aerogels; synthesis and characterization of melamine-formaldehyde aerogels; structural transformation and precursor phenomena in advanced materials; magnetic ultrathin films, surfaces, and overlayers; ductile-phase toughening of refractory-metal intermetallics; particle-solid interactions; electronic structure evolution of metal clusters; and nanoscale lithography induced chemically or physically by modified scanned probe microscopy

  4. Biofunctionalization of polyelectrolyte microcapsules with biotinylated polyethylene glycol-grafted liposomes.

    Science.gov (United States)

    Gao, Jie; Reibetanz, Uta; Venkatraman, Subbu; Neu, Björn

    2011-08-11

    Hollow polyelectrolyte microcapsules (PEMC) are prepared using layer-by-layer self-assembly of polyelectrolytes on melamine formaldehyde templates, followed by template dissolution, and subsequent coating with biotinylated polyethylene glycol-grafted liposomes. These potential site-specific carrier systems show a high specificity for NeutrAvidin binding and a strong resistance against unspecific protein binding. It is concluded that this design with NeutrAvidin as the outermost layer of such capsules provides an ideal platform for the biofunctionalization of PEMC as drug delivery systems or as artificial cell-like structures for biomimetic studies. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Cerium carbide embedded in nitrogen-doped carbon as a highly active electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Wang, Wei; Xue, Shouyuan; Li, Jinmei; Wang, Fengxia; Kang, Yumao; Lei, Ziqiang

    2017-08-01

    In this study, cerium carbide embedded in nitrogen-doped carbon (CeCx-NC) has been prepared by a facile pyrolysis of melamine formaldehyde resin containing rare-earth element. The as-prepared CeCx-NC catalyst shows high electrocatalytic activity towards oxygen reduction reaction (ORR) in alkaline electrolyte, with the half wave potential being almost equal to commercial Pt/C, nearly four electron transfer number, good toxicity tolerance durability and cycle stability. This rare-earth metal carbide opens a novel avenue for advanced electrocatalyst.

  6. Pet food recalls and pet food contaminants in small animals.

    Science.gov (United States)

    Bischoff, Karyn; Rumbeiha, Wilson K

    2012-03-01

    Most pet foods are safe, but incidents of chemical contamination occur and lead to illness and recalls. There were 11 major pet food recalls in the United States between 1996 and 2010 that were due to chemical contaminants or misformulations: 3 aflatoxin, 3 excess vitamin D3, 1 excess methionine, 3 inadequate thiamine, and 1 adulteration with melamine and related compounds and an additional 2 warnings concerning a Fanconilike renal syndrome in dogs after ingesting large amounts of chicken jerky treat products. This article describes clinical findings and treatment of animals exposed to the most common pet food contaminants.

  7. Bis(melaminium tartrate dihydrate

    Directory of Open Access Journals (Sweden)

    Hong Su

    2009-04-01

    Full Text Available In the title compound, 2C3H7N6+·C4H4O62−·2H2O, in which the complete anion is generated by crystallographic twofold symmetry, there are O—H...O, N—H...O and N—H...N hydrogen-bonding interactions between neighbouring moieties, forming layers parallel to the bc plane. In addition, π–π contacts [centroid–centroid distance = 3.6541 (9 Å] between the six-membered rings of the melamine cations are observed.

  8. Development of a Halogen Free Flame Retardant Masterbatch for Polypropylene Fibers

    Directory of Open Access Journals (Sweden)

    François Rault

    2015-02-01

    Full Text Available The efficiency of new phosphinates, in combination with melamine cyanurate, was studied using different polypropylene textile structures. The influence of different ratios up to a total amount of 6 wt% in the polypropylene fiber was investigated using the limiting oxygen index (LOI and cone calorimeter method for research purposes, while the performances were correlated to the standards FMVSS 302 (Federal Motor Vehicle Safety Standards and DIN 4102-l (Deutsches Institut für Normung used more specifically for automotive and building sector.

  9. Pyrolysis Synthesized g-C3N4 for Photocatalytic Degradation of Methylene Blue

    Directory of Open Access Journals (Sweden)

    Gang Xin

    2013-01-01

    Full Text Available Graphitic carbon nitride (g-C3N4 was synthesized at 520°C by the pyrolysis of cyanamide, dicyandiamide, and melamine. The samples were characterized by X–ray diffraction (XRD, UV-visible diffuse reflectance spectra, Fourier transform infrared spectroscopy (FT-IR, and elemental analyzer. The photocatalytic activity of g-C3N4 was evaluated by the photodegrading experiments of methylene blue (MB. The results indicated that g-C3N4. A photocatalytic mechanism presumed the MB photodegradation over the C3N4 photocatalyst is attributed to photogenerated electron impelled multistep reduction of O2.

  10. Surface Roughness of Composite Panels as a Quality Control Tool

    Directory of Open Access Journals (Sweden)

    Onur Ulker

    2018-03-01

    Full Text Available This paper describes a study of the quantify surface roughness of experimentally manufactured particleboards and sandwiched panels having fibers on the surface layers. Surface quality of specimens before and after being overlaid with thin melamine impregnated papers was determined by employing profilometer equipment. Roughness measurements and Janka hardness were carried out on the specimens conditioned at 60% and 95% relative humidity levels. Based on the findings in this work, surface roughness of the specimens that were exposed two relative humidity exposure showed significant differences from each others. Data determined in this study could be beneficial to understand behavior of such panels exposed different humidity levels.

  11. Creep of MDF panels under constant load and cyclic environmental conditions. Influence of surface coating

    OpenAIRE

    Fernández-Golfín Seco, J. I.; Díez Barra, M. Rafael

    1997-01-01

    Four different strategies of surface coating (based on 80 g m2 melamin impregnated papers) were used on 19 mm thick commercial MDF panels to assess its reological behaviour under cyclic humidity conditions (20ºC 30 % rh-20ºC 90 % rh). Three different levels of stress (20 %, 30 % and 40 %), based on the ultimate load in bending, were used. Tests were conducted by means of the three points load system. For the same stress level, the relative creep of MDF panels was higher than that in par...

  12. Multiple encapsulation of LANL waste using polymers. Final report

    International Nuclear Information System (INIS)

    Schwartz, R.L.

    1994-01-01

    Polymer encapsulation of lead shielding/blasting grit (surrogate) mixed waste was optimized at bench scale using melamine formaldehyde, polyurethane, and butadiene thermosetting polymers. Three pellet-based intermediate waste forms, and a final waste form, were prepared, each providing an additional level of integrity. Encapsulated waste integrity was measured by chemical and physical techniques. Compliance was established using the Toxicity Characteristic Leaching Procedure. Equipment appropriate to pilot-scale demonstration of program techniques was investigated. A preliminary equipment list and layout, and process block flow diagram were prepared

  13. Reduction of nitrogen- and carbon-based pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, W.E.

    1990-05-22

    This patent describes a process for educing the concentration of nitrogen oxides in an oxygen-rich effluent from the combustion of a carbonaceous fuel. It comprises: injecting a solution comprising at least one additive compound selected from the group consisting of guanidine, guanidine carbonate, biguanide, guanylurea sulfate, melamine, dicyandiamide, biuret, 1,1{prime}-azobisformamide, methylol urea, methylol urea-urea condensation product, dimethylol urea, methyl urea, and dimethyl urea, at a concentration and a temperature effective to achieve reduction in nitrogen oxide levels in the effluent.

  14. Kemin bakom framtidens avgasrening : En studie av ureasönderfall under kvävgasatmosfär

    OpenAIRE

    Le, Tan

    2011-01-01

    The purpose of this work was to provide a better understanding of urea’s decomposition and byproduct formation in an SCR system on heavy trucks. In my experimental setup with TGA-DSC-FTIR (a combination of two thermal analysis methods and a method for gas phase detection), an FTIR method for urea in the gas phase was developed for the qualitative and quantitative determination of urea and its decomposition products. Chemicals such as urea, biuret, cyanuric acid and melamine of p.a. quality we...

  15. High performance SERS on nanoporous gold substrates synthesized by chemical de-alloying a Au-based metallic glass

    Science.gov (United States)

    Xue, Yanpeng; Scaglione, Federico; Rizzi, Paola; Battezzati, Livio

    2017-12-01

    A Au20Cu48Ag7Pd5Si20 metallic glass precursor has been used to synthesize nanoporous gold by chemical de-alloying in a mixture of HNO3 and HF. Gold ligaments of size ranging from 45 to 100 nm were obtained as a function of HNO3 concentration, electrolyte temperature and de-alloying time. The as-prepared nanoporous gold exhibited strong surface enhanced Raman scattering (SERS) effect using 4,4‧-bi-pyridine as probe molecule. For application in melamine sensing, the detection limit of 10-6 M was achieved, which indicated that this biocompatible material has great potential as SERS active substrate.

  16. Chemistry and Materials Science progress report, first half FY 1992. Weapons-Supporting Research and Laboratory Directed Research and Development

    Energy Technology Data Exchange (ETDEWEB)

    1992-07-01

    This report contains sections on: Fundamentals of the physics and processing of metals; interfaces, adhesion, and bonding; energetic materials; plutonium research; synchrotron radiation-based materials science; atomistic approach to the interaction of surfaces with the environment: actinide studies; properties of carbon fibers; buried layer formation using ion implantation; active coherent control of chemical reaction dynamics; inorganic and organic aerogels; synthesis and characterization of melamine-formaldehyde aerogels; structural transformation and precursor phenomena in advanced materials; magnetic ultrathin films, surfaces, and overlayers; ductile-phase toughening of refractory-metal intermetallics; particle-solid interactions; electronic structure evolution of metal clusters; and nanoscale lithography induced chemically or physically by modified scanned probe microscopy.

  17. In-situ phosphatizing coatings for aerospace, OEM and coil coating applications

    Science.gov (United States)

    Neuder, Heather Aurelia

    The current metal coating process is a multi-step process. The surface is cleaned, primered, dried and then painted. The process is labor intensive and time consuming. The wash primer is a conversion coating, which prepares metal surface for better paint adhesion. The wash primers currently used often contain hexavalent chromium (Cr6+), which seals the pores in the conversion coating. The presence of hexavalent chromium, a known carcinogen, and volatile organic compounds (VOCs) make waste disposal expensive and pose dangers to workers. The novel technique of in-situ phosphatizing coating (ISPC) is a single-step, chrome-free alternative to the present coating practice. Formulation of an ISPC involves predispersal of an in-situ phosphatizing reagent (ISPR) into the paint system to form a stable formulation. The ISPR reacts with the metal surface and bonds with the paint film simultaneously, which eliminates the need for a conversion coating. In acid catalyzed paint systems, such as polyester-melamine paints, the ISPR also catalyzes cross-linking reactions between the melamine and the polyester polyols. ISPCs are formulated using commercially available coating systems including: polyester-melamine, two-component epoxy, polyurethane and high-hydroxy content polyester-melamine coil coating. The ISPCs are applied to metal substrates and their performances are evaluated using electrochemical, thermal and standard American Society for Testing and Materials (ASTM) testing methods. In addition, ISPCs were designed and formulated based on: (1) phosphate chemistry, (2) polymer chemistry, (3) sol-gel chemistry, and (4) the ion-exchange principle. Organo-functionalized silanes, which serve as excellent coupling and dispersion agents, are incorporated into the optimized ISPC formula and evaluated using standard ASTM testing methods and electrochemical spectroscopy. Also, an ion-exchange pigment, which leads to better adhesion by forming a mixed metal silicate surface, is

  18. Material Analysis for a Fire Assessment.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Alexander; Nemer, Martin B.

    2014-08-01

    This report consolidates technical information on several materials and material classes for a fire assessment. The materials include three polymeric materials, wood, and hydraulic oil. The polymers are polystyrene, polyurethane, and melamine- formaldehyde foams. Samples of two of the specific materials were tested for their behavior in a fire - like environment. Test data and the methods used to test the materials are presented. Much of the remaining data are taken from a literature survey. This report serves as a reference source of properties necessary to predict the behavior of these materials in a fire.

  19. Alkali-Assisted Synthesis of Nitrogen Deficient Graphitic Carbon Nitride with Tunable Band Structures for Efficient Visible-Light-Driven Hydrogen Evolution.

    Science.gov (United States)

    Yu, Huijun; Shi, Run; Zhao, Yunxuan; Bian, Tong; Zhao, Yufei; Zhou, Chao; Waterhouse, Geoffrey I N; Wu, Li-Zhu; Tung, Chen-Ho; Zhang, Tierui

    2017-04-01

    A facile synthetic strategy for nitrogen-deficient graphitic carbon nitride (g-C 3 N x ) is established, involving a simple alkali-assisted thermal polymerization of urea, melamine, or thiourea. In situ introduced nitrogen vacancies significantly redshift the absorption edge of g-C 3 N x , with the defect concentration depending on the alkali to nitrogen precursor ratio. The g-C 3 N x products show superior visible-light photocatalytic performance compared to pristine g-C 3 N 4 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. In situ hydrothermal synthesis of g-C3N4/TiO2 heterojunction photocatalysts with high specific surface area for Rhodamine B degradation

    Science.gov (United States)

    Hao, Ruirui; Wang, Guohong; Jiang, Chuanjia; Tang, Hua; Xu, Qingchuan

    2017-07-01

    Semiconductor-based photocatalysis is a promising method for degradation of environmental pollutants, but the activity of most widely used photocatalysts such as titania (TiO2) is still unsatisfactory under visible light. Herein, we synthesized a highly efficient visible-light-responsive heterojunction catalysts based on graphitic carbon nitride (g-C3N4) and TiO2. The g-C3N4/TiO2 heterojunction composites with high specific surface area were prepared via in situ hydrothermal synthesis followed by calcination, using titanium tetrachloride (TiCl4) and melamine as precursors. Interesting, HCl from the hydrolysis of TiCl4 served as the proton source to acidify the melamine. The g-C3N4/TiO2 heterojunction composites exhibited higher photocatalytic performance for decomposition of Rhodamine B (RhB) than pure g-C3N4 or TiO2 under visible light irradiation. The high activity can be ascribed to the high specific surface area (up to 115.6 m2 g-1) of the g-C3N4/TiO2 composites and a synergistic heterojunction structure between TiO2 and g-C3N4. Moreover, the photocatalytic performances of the g-C3N4/TiO2 composites rely on the content of melamine in the synthesis precursors: with an optimum melamine content (3 g for 0.5 mL of TiCl4), the sample showed the highest photocatalytic performance, which is superior to pure TiO2 and g-C3N4 by a factor of 18.7 and 3.5, respectively. Active species trapping experiments revealed that superoxide radicals and photogenerated holes played crucial roles in the photocatalytic reactions. The results will provide new ideas for the smart design and development of g-C3N4-based highly active photocatalysts with ultrahigh specific surface area for environmental and energy applications.

  1. STUDY OF CRYSTALLIZATION OF CALCIUM SULFATE DIHYDRATE THAT HAS POLYMER ADDITIVES

    Directory of Open Access Journals (Sweden)

    Ustinova Yuliya Valer'evna

    2012-10-01

    A. It is identified that additives based on polymers of different origin affect processes of crystallization, the size and shape of crystals. B. The X-ray diffraction analysis has proven that molecules of polymer additives do not penetrate into the gypsum structure and the chemical composition of the product does not change. C. Methods of thermal analysis have proven that the introduction of polymer additives does not produce any adverse impact on the stability of gypsum crystals, if exposed to temperature fluctuations. D. The major impact produced onto crystallization is the one of the super plasticizer based on the sulfonated melamine-formaldehyde resin.

  2. Pyrolysis Synthesized g-C3N4 for Photocatalytic Degradation of Methylene Blue

    OpenAIRE

    Xin, Gang; Meng, Yali

    2013-01-01

    Graphitic carbon nitride (g-C3N4) was synthesized at 520°C by the pyrolysis of cyanamide, dicyandiamide, and melamine. The samples were characterized by X–ray diffraction (XRD), UV-visible diffuse reflectance spectra, Fourier transform infrared spectroscopy (FT-IR), and elemental analyzer. The photocatalytic activity of g-C3N4 was evaluated by the photodegrading experiments of methylene blue (MB). The results indicated that g-C3N4. A photocatalytic mechanism presumed the MB photodegradation o...

  3. Multiple encapsulation of LANL waste using polymers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, R.L.

    1994-08-12

    Polymer encapsulation of lead shielding/blasting grit (surrogate) mixed waste was optimized at bench scale using melamine formaldehyde, polyurethane, and butadiene thermosetting polymers. Three pellet-based intermediate waste forms, and a final waste form, were prepared, each providing an additional level of integrity. Encapsulated waste integrity was measured by chemical and physical techniques. Compliance was established using the Toxicity Characteristic Leaching Procedure. Equipment appropriate to pilot-scale demonstration of program techniques was investigated. A preliminary equipment list and layout, and process block flow diagram were prepared.

  4. Analysis of cement superplasticizers and grinding aids a literature survey

    International Nuclear Information System (INIS)

    Ervanne, H.; Hakanen, M.

    2007-04-01

    This literature survey reviews the methods for analysis of cement plasticizers and organic grounding aids in cement solutions in preparation of grouts/concrete and methods for determination of plasticizers and grinding aids in groundwater conditions. The survey focuses on three different types of superplasticizers: sulphonated naphthalene condensates, sulphonated melamine condensates and polycarboxylates. There are various organic grinding aids, such as alkanolamines, glycols or phenolic compounds, used in the cement industry. This review is concerned with the following compounds: triethylenetetramine, tetraethylenepentamine, diethanolamine, triethanolamine, triisopropanolamine, ethyleneglycol, diethyleneglycol, aminoethylethanolamine, hydroxyethyl diethylenetriamine and phenol. (orig.)

  5. Facile fabrication of mesoporous g-C3N4/TiO2 photocatalyst for efficient degradation of DNBP under visible light irradiation

    Science.gov (United States)

    Wei, Xiao-Na; Wang, Hui-Long; Wang, Xin-Kui; Jiang, Wen-Feng

    2017-12-01

    In this paper, a novel thermal condensation method was developed for preparing mesoporous g-C3N4/TiO2 composite by using PAA-Ti/TiO2 and melamine as co-precursors. This method can not only ensure the incorporation of TiO2 nanoparticles into g-C3N4 matrix but also lead to the formation of mesoporous structures. In the heating process, polyacrylate (PAA) in the PAA-Ti/TiO2 composites can volatilize to produce carbonous gases and its volatilization temperature falls into the temperature range for melamine condensation, which makes PAA-Ti/TiO2 a suitable pore-forming agent for fabricating mesoporous g-C3N4/TiO2. The largest surface area for the fabricated mesoporous g-C3N4/TiO2 was found to be 268 m2g-1, which was approximately 7 or 12 times higher than that of TiO2 or g-C3N4. The mesoporous g-C3N4/TiO2 composite exhibited excellent reproducibility and good performance in the photocatalytic decomposition of dinitro butyl phenol (DNBP) under visible-light illumination. The enhanced photocatalytic efficiency can be attributed to the synergetic effects of large surface area and the formation of heterojunction interface between g-C3N4 and TiO2.

  6. Synergic Effect between Adsorption and Photocatalysis of Metal-Free g-C3N4 Derived from Different Precursors.

    Directory of Open Access Journals (Sweden)

    Huan-Yan Xu

    Full Text Available Graphitic carbon nitride (g-C3N4 used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500 had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500, which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed.

  7. Synergic Effect between Adsorption and Photocatalysis of Metal-Free g-C3N4 Derived from Different Precursors

    Science.gov (United States)

    Xu, Huan-Yan; Wu, Li-Cheng; Zhao, Hang; Jin, Li-Guo; Qi, Shu-Yan

    2015-01-01

    Graphitic carbon nitride (g-C3N4) used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB) under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500) had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500), which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO) was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed. PMID:26565712

  8. Growth of g-C3N4 Layer on Commercial TiO2 for Enhanced Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Min Fu

    2014-01-01

    Full Text Available Novel visible light photocatalytic graphitic carbon nitride/TiO2 (g-C3N4/TiO2 composite samples were synthesized by heating mixtures of melamine and commercial TiO2(TO at different weight ratios. The samples were characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscopy (TEM, photoluminescence spectroscopy (PL, Fourier transform infrared spectroscopy (FTIR, and UV-visible diffused reflectance spectroscopy (UV-vis DRS. Characterization confirms formation of nanocomposites of g-C3N4/TiO2. At the optimized precursor weight ratio (melamine:mTiO2=2.5, the samples exhibited highest adsorption capacity and visible light photocatalytic activity, measured by degradation of methylene blue (MB. Under visible light irradiation, the excited electrons on the surface of g-C3N4 transfer easily to the conduction band (CB of TiO2 via the well-built heterojunction. The g-C3N4/TiO2 nanocomposites exhibit enhanced visible light catalytic activity due to increased visible light adsorption and effective separation of photogenerated electron-hole pairs. These g-C3N4/TiO2 nanocomposites could find broad applicability in environmental protection due to their excellent visible light photocatalytic property and facile, cost-effective preparation process.

  9. Effect of nitrogen precursors on the electrochemical performance of nitrogen-doped reduced graphene oxide towards oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Soo, Li Ting, E-mail: nicolesoo90@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Loh, Kee Shyuan, E-mail: ksloh@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Mohamad, Abu Bakar, E-mail: drab@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Daud, Wan Ramli Wan, E-mail: wramli@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Wong, Wai Yin, E-mail: waiyin.wwy@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); School of Engineering, Taylor' s University' s Lakeside Campus, No. 1, Jalan Taylor' s, 46500 Subang Jaya, Selangor (Malaysia)

    2016-08-25

    A series of nitrogen-doped reduced graphene oxides (NGs) with different ratios are synthesized by thermal annealing of graphene oxide with melamine or urea. The total nitrogen content in NG is high, with values of up to 5.88 at.%. The NG samples prepared by melamine exhibited thin transparent graphene sheets structure, with consist of higher nitrogen doping level and quaternary N content compared to those NG samples prepared from urea. Electrochemical characterizations show that NG is a promising metal-free electrocatalyst for an oxygen reduction reaction (ORR). Incorporation of nitrogen atoms into graphene basal plane can enhances its electrocatalytic activity toward ORR in alkaline media. The onset potential and mean number of electron transfers on NG 1 are −0.10 V and 3.80 respectively, which is higher than that of reduced graphene oxide (−0.15 V, 3.52). This study suggests that quaternary-N of the NG samples is the active site which determines the ORR activity Moreover, the NG samples with the transparent layer of graphene-like structure have better ORR performances than that of bulk graphite-like NG samples. - Highlights: • Synthesis of nitrogen-doped graphene (NG) via thermal annealing. • The effects of the nitrogen precursors on the synthesized NG are discussed. • Electrochemical performances of the NG are correlated to N doping and EASA. • Graphitic-N is proposed to be the active site for ORR.

  10. g-C{sub 3}N{sub 4} decorated ZnO nanorod arrays for enhanced photoelectrocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Pan-Yong; Su, Yu-Zhi; Chen, Gao-Feng [School of Chemistry and Chemical Engineering/Guangzhou Key Laboratory for Environmentally Functional Materials and Technology, Guangzhou University, Guangzhou 510006 (China); Luo, Zhuo, E-mail: lz8215353@126.com [Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha 410022 (China); Xing, Shu-Yang [Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha 410022 (China); Li, Nan [School of Chemistry and Chemical Engineering/Guangzhou Key Laboratory for Environmentally Functional Materials and Technology, Guangzhou University, Guangzhou 510006 (China); Liu, Zhao-Qing, E-mail: lzqgzu@gzhu.edu.cn [School of Chemistry and Chemical Engineering/Guangzhou Key Laboratory for Environmentally Functional Materials and Technology, Guangzhou University, Guangzhou 510006 (China)

    2015-12-15

    Graphical abstract: - Highlights: • Highly ordered g-C{sub 3}N{sub 4}/ZnO NRAs were prepared through thermal condensation of melamine. • Efficient electron–hole pair separation and transfer rates were achieved in the heterojunction. • The as-prepared g-C{sub 3}N{sub 4}/ZnO NRAs exhibit enhanced photoelectrocatalytic performance. - Abstract: Heterojunction can not only offer a wide range of solar light absorption but also facilitate the separation of photoinduced charge carriers, and thereby lead to enhanced photoelectrochemical efficiency. Herein, we report the heterostructured g-C{sub 3}N{sub 4}/ZnO nanorod arrays (NRAs) for enhanced photoelectrocatalytic performance. The g-C{sub 3}N{sub 4} shell layer of about 20–30 nm was coated on the surface of ZnO nanorod uniformly through thermal annealing the melamine precursor. Compared to the pristine ZnO and g-C{sub 3}N{sub 4}, the as-prepared g-C{sub 3}N{sub 4}/ZnO NRAs exhibit enhanced photoelectrocatalytic activity for methylene blue (MB) decolorization under visible light illumination. This enhancement of photoelectrocatalytic performance may be mainly attributed to improved separation efficiency of charge carriers from photoexcited g-C{sub 3}N{sub 4} to ZnO across the g-C{sub 3}N{sub 4}/ZnO interfaces.

  11. Magnetic properties of carbon-encapsulated Fe–Ni alloy nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Aibing [College of Chemistry, Jilin University, Changchun 130012 (China); Department of Environmental and Chemical Engineering, Tangshan College, Tangshan, 063000 (China); Gao, Jiajia; Chen, Xiaodong; Yang, Xuwei [College of Chemistry, Jilin University, Changchun 130012 (China); Yang, Hua, E-mail: huayang86@sina.com [College of Chemistry, Jilin University, Changchun 130012 (China)

    2014-01-15

    Highlights: • Fe-Ni@C alloy nanoparticles were fabricated using melamine as carbon source. • Their structure, morphology and magnetic properties were researched. • The highest M{sub S} of Fe-Ni@C alloy is 132 emu/g. -- Abstract: Carbon-encapsulated Fe–Ni alloy nanoparticles (Fe–Ni@C) have been fabricated with different Ni/Fe ratio by an solid-state route using melamine as carbon source. The structure and morphology of Fe–Ni@C nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The XRD characterization results reveal that all products are alloys with no carbide impurity. The TEM and HRTEM observations show that the alloy nanoparticles are encapsulated in carbon shells. Additionally, the reactions involved in the syntheses are speculated. The variation of magnetic properties of Fe–Ni@C with Ni/Fe has been discussed according to the room temperature VSM measurement results.

  12. Adverse child health impacts resulting from food adulterations in the Greater China Region.

    Science.gov (United States)

    Li, Wai Chin; Chow, Chin Fung

    2017-09-01

    Food adulteration has a long history in human society, and it still occurs in modern times. Because children are relatively vulnerable to food adulterants, studying the health impacts of food adulteration on children is important. This article provides an overview of the child health impacts of food adulterants in two recent food adulteration incidents in the Greater China Region: (1) a plasticizer incident in Taiwan and (2) a 2,4,6-triamino-1,3,5-triazine (melamine)-tainted milk incident in China. The involved food adulterants, di-(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DiNP) and melamine, are harmful to the hippocampus, kidneys, reproductive organs and immune system of children, and they also increase the risk of cancer. To detect food adulteration and to avoid further harm caused by food adulteration, simple screening methods have been developed, and they have recently emerged as a new focus area for research. This article also summarizes the simple screening methods used to analyse the aforementioned food adulterants and reports how governments reacted to the recent food incidents. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  13. Discriminant analysis of milk adulteration based on near-infrared spectroscopy and pattern recognition

    Science.gov (United States)

    Liu, Rong; Lv, Guorong; He, Bin; Xu, Kexin

    2011-03-01

    Since the beginning of the 21st century, the issue of food safety is becoming a global concern. It is very important to develop a rapid, cost-effective, and widely available method for food adulteration detection. In this paper, near-infrared spectroscopy techniques and pattern recognition were applied to study the qualitative discriminant analysis method. The samples were prepared and adulterated with one of the three adulterants, urea, glucose and melamine with different concentrations. First, the spectral characteristics of milk and adulterant samples were analyzed. Then, pattern recognition methods were used for qualitative discriminant analysis of milk adulteration. Soft independent modeling of class analogy and partial least squares discriminant analysis (PLSDA) were used to construct discriminant models, respectively. Furthermore, the optimization method of the model was studied. The best spectral pretreatment methods and the optimal band were determined. In the optimal conditions, PLSDA models were constructed respectively for each type of adulterated sample sets (urea, melamine and glucose) and all the three types of adulterated sample sets. Results showed that, the discrimination accuracy of model achieved 93.2% in the classification of different adulterated and unadulterated milk samples. Thus, it can be concluded that near-infrared spectroscopy and PLSDA can be used to identify whether the milk has been adulterated or not and the type of adulterant used.

  14. Direct Detection of Dilute Solid Chemicals with Responsive Lateral Organic Diodes.

    Science.gov (United States)

    Huang, Jia; Zhang, Guoqian; Zhao, Xingang; Wu, Xiaohan; Liu, Dapeng; Chu, Yingli; Katz, Howard E

    2017-09-13

    Organic field-effect transistors (OFETs) have emerged as promising sensors targeting chemical analytes in vapors and liquids. However, the direct detection of solid chemicals by OFETs has not been achieved. Here for the first time, we describe the direct detection of solid chemical analytes by organic electronics. An organic diode structure based on a horizontal side-by-side p-n junction was adopted and shown to be superior to OFETs for this purpose. The diodes showed more than 40% current decrease upon exposure to 1 ppm melamine powders. The estimated detection limit to melamine can potentially reach the ppb range. This is the first demonstration of an electronic signal from an interaction between a solid and an organic p-n junction directly, which suggests that our lateral organic diodes are excellent platforms for the development of future sensors when direct detection of solid chemicals is needed. The approach developed here is general and can be extended to chemical sensors targeting various analytes, opening unprecedented opportunities for the development of low-cost and high-performance solid chemical sensors.

  15. Hot-Pressing Method To Prepare Imidazole-Based Zn(II) Metal-Organic Complexes Coatings for Highly Efficient Air Filtration.

    Science.gov (United States)

    Wang, Ani; Fan, Ruiqing; Zhou, Xuesong; Hao, Sue; Zheng, Xubin; Yang, Yulin

    2018-03-21

    Particulate matters (PMs) air pollution has become a serious environmental issue due to its great threat to human health. Herein, metal-organic complexes PBM-Zn1 and PBM-Zn2 coatings (noted as PBM-Zn-Filter) have been produced by the hot-pressing method on various substrates for the first time. Layer-by-layer PBM-Zn-Filters were also obtained through varying hot-pressing cycles. The obtained PBM-Zn-Filters with high robustness show excellent performance in PMs removal. In particular, benefiting from thelarger conjugation system, micropore structure, lower pressure drop, higher electrostatic potential ζ, and electron cloud exposed metal center of PBM-Zn2 (DFT calculations), PBM-Zn2@melamine foam-4 gives the highest removal rates, PM2.5:99.5% ± 1.2% and PM10:99.3% ± 1.1%, and the removal efficiency for capture PM2.5 and PM10 particles in cigarette smoke were both retained at high levels (>95.5%) after 24 h tests. More importantly, a homemade mask is made up by imbedding the PBM-Zn2@melamine foam-4 into a commercial breathing mask, which shows higher removal efficiency, lower pressure drop, smaller thickness, and higher quality factor than two commercial breathing masks, the PMs removal efficiencies for both PM2.5 and PM10 are 99.6% ± 0.5% and 99.4% ± 0.8%, and acceptable air resistance are demonstrated.

  16. A confined "microreactor" synthesis strategy to three dimensional nitrogen-doped graphene for high-performance sodium ion battery anodes

    Science.gov (United States)

    Li, Jiajie; Zhang, Yumin; Gao, Tangling; Han, Jiecai; Wang, Xianjie; Hultman, Benjamin; Xu, Ping; Zhang, Zhihua; Wu, Gang; Song, Bo

    2018-02-01

    In virtue of abundant sodium resources, sodium ion batteries (SIBs) have been regarded as one of the most promising alternatives for large-scale energy storage applications. However, the absence of a suitable anode material makes it difficult to realize these applications. Here, we demonstrate an effective synthesis strategy of using a "microreactor" consisting of melamine fiber (inside) and graphene oxide (GO, outside) to fabricate three dimensional (3D) nitrogen doped (N-doped) graphene as high-performance anode materials for sodium ion batteries. Through a controlled pyrolysis, the inside melamine fiber and the outside GO layer has been converted into N-doped graphene and reduced graphene oxide (r-GO) respectively, and thus the "microreactor" is transformed into interconnected 3D N-doped graphene structures. Such highly desired 3D graphene structures show reversible sodium storage capacities up to ∼305 mA h g-1 after 500 cycles at a current density of 0.2 A g-1 and promising long cycling stability with a stable capacity of ∼198 mA h g-1 at 5 A g-1 after 5000 cycles. The high capacity and superior durability in combination with the facile synthesis procedure of the 3D graphene structure make it a promising anode material for SIBs and other energy storage applications.

  17. Alkyd-amino resins based on waste PET for coating applications

    International Nuclear Information System (INIS)

    Torlakoglu, A.; Gueclue, G.

    2009-01-01

    Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40 mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 deg. C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins

  18. Equilibrium moisture content of OSB panels produced with veneer inclusion and different types of adhesive

    Directory of Open Access Journals (Sweden)

    Lourival Marin Mendes

    2014-03-01

    Full Text Available The aim of this study was to evaluate different statistical models to estimate the equilibrium moisture content of OSB panels exposed to different conditions of air temperature and relative humidity, And also to evaluate the influence of the adhesive and veneer inclusion in the equilibrium moisture content. The panels were produced with three different adhesive types (phenol-formaldehyde - FF, melamine-urea-formaldehyde - MUF, and phenol-melamine-urea-formaldehyde - PMUF and with and without veneer inclusion. The evaluation of the equilibrium moisture content of the panels was carried out at temperatures of 30, 40 and 50°C and relative humidity of 40, 50, 60, 70, 80 and 90%. The modeling of equilibrium moisture content was performed using the statistical non-linear and polynomial models. In general, the polynomial models are most indicated for determining the equilibrium moisture content of OSB. The models adjusted only with air relative humidity presented the best precision measurements. The type of adhesive affected the equilibrium moisture content of the panels, being observed for adhesives PMUF and FF the same trend of variation, and the highest values obtained for the panels produced with adhesive MUF. The veneer inclusion decreased the equilibrium moisture content only in the panels with MUF adhesive.

  19. Formation of graphitic carbon nitride and boron carbon nitride film on sapphire substrate

    Science.gov (United States)

    Kosaka, Maito; Urakami, Noriyuki; Hashimoto, Yoshio

    2018-02-01

    As a novel production method of boron carbon nitride (BCN) films, in this paper, we present the incorporation of B into graphitic carbon nitride (g-C3N4). First, we investigated the formation of g-C3N4 films via chemical vapor deposition (CVD) using melamine powder as the precursor. The formation of g-C3N4 films on a c-plane sapphire substrate was confirmed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy measurements. The deposition temperature of g-C3N4 films was found to be suitable between 550 and 600 °C since the degradation and desorption of hexagonal C–N bonds should be suppressed. As for BCN films, we prepared BCN films via two-zone extended CVD using ammonia borane as the B precursor. Several XPS signals from B, C, and N core levels were detected from B-incorporated g-C3N4 films. While the N composition was almost constant, the marked tendencies for increasing B composition and decreasing C composition were achieved with the increase in the B incorporation, indicating the incorporation of B atoms by the substitution for C atoms. Optical absorptions were shifted to the high-energy side by B incorporation, which indicates the successful formation of BCN films using melamine and ammonia borane powders as precursors.

  20. Preparation and characterization of microencapsulated phase change material with low remnant formaldehyde content

    Energy Technology Data Exchange (ETDEWEB)

    Li Wei [Tianjin Municipal Key Lab of Fiber Modification and Functional Fibers, Institute of Functional Fibers, Tianjin Polytechnic University, Tianjin 300160 (China); Zhang Xingxiang [Tianjin Municipal Key Lab of Fiber Modification and Functional Fibers, Institute of Functional Fibers, Tianjin Polytechnic University, Tianjin 300160 (China)], E-mail: zhangpolyu@yahoo.com.cn; Wang Xuechen; Niu Jianjin [Tianjin Municipal Key Lab of Fiber Modification and Functional Fibers, Institute of Functional Fibers, Tianjin Polytechnic University, Tianjin 300160 (China)

    2007-12-15

    Microencapsulated phase change materials (MicroPCMs) were synthesized by in situ polymerization using melamine-formaldehyde (MF) resin as shell and n-octadecane as core. The employed MF prepolymer was prepared by incorporating formaldehyde once and melamine for three times. The effects of dropping rate of MF prepolymer on the surface morphology, dispersibility and thermal stability of the microcapsules were systematically investigated using scanning electronic microscopy (SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and thermogravimetry analysis (TG). The results show that, with the dropping rate of the MF prepolymer decreasing, the flocculation phenomenon of microcapsules decreases and the globular surface becomes smoother; and the thermal stability increases regularly. The average diameter of the microcapsules is about 2.2 {mu}m and the diameter distribution is narrow. The enthalpy of the microcapsules containing 59 wt% n-octadecane is 144 J g{sup -1}. In addition, the remnant formaldehyde content of the microcapsules is 68.6 mg kg{sup -1}, which is highly attractive for the application of MicroPCMs.

  1. Melaminium nitrate–melamine–water (1/1/1

    Directory of Open Access Journals (Sweden)

    Farook Adam

    2010-11-01

    Full Text Available In the crystal structure of the title salt, C3H7N6+·NO3−·C3H6N6·H2O, the asymmetric unit consists of two neutral melamine (1,3,5-triazine-2,4,6-triamine molecules, two melaminium cations, two nitrate anions and two solvent water molecules. One of the nitrate anions is disordered over two sets of positions, with a refined occupancy ratio of 0.909 (3:0.091 (3. The cations and neutral molecules are approximately planar, with maximum deviations of 0.018 (2, 0.024 (2, 0.019 (2 and 0.007 (2 Å for each, respectively. In the crystal structure, melaminium cations and netural melamine molecules self-assemble via N—H...N hydrogen bonds to form a supramolecular hexagonal-shaped motif. In addition, the nitrate anions and water molecules are connected by N—H...O hydrogen bonds to form a three-dimensional network.

  2. Alkyd-amino resins based on waste PET for coating applications.

    Science.gov (United States)

    Torlakoğlu, A; Güçlü, G

    2009-01-01

    Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 degrees C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins.

  3. Analysis of a survey database of pet food-induced poisoning in North America.

    Science.gov (United States)

    Rumbeiha, Wilson K; Agnew, Dalen; Maxie, Grant; Hoff, Brent; Page, Connie; Curran, Paul; Powers, Barbara

    2010-06-01

    Following the outbreak of pet food-induced nephrotoxicity in March 2007, a voluntary online survey of all AAVLD-accredited laboratories, commercial laboratories, and veterinary clinics across North America was conducted. There was no information on toxicity of melamine or factors affecting the disease outcome following exposure to melamine in pets. Data were collected from affected pets to learn about the disease outcome and the affected pet population. The web-based electronic survey used the online tool, Survey Monkey™. Data were collected between April 5 and October 31, 2007. Four hundred fifty-one cases of 586 reported cases met the criteria for inclusion in the study. Most reported cases were from California, Texas, Michigan, Florida, and Ontario. Of the 451 cases, 424 were reported as affected. Of these, 278 cases (65.6%) were cats and 146 (34.4%) were dogs. A total of 278 pets (171 cats and 107 dogs) were reported to have died (a ratio of 1.6:1). However, within species, there was a higher percentage of deceased dogs (73.3%) than cats (61.5%). Of the affected pet population, older male cats with preexisting disease conditions were more likely to be deceased. Analysis of the pets in this large database of naturally affected pets yielded interesting findings. It showed that more cats than dogs were affected and also that preexisting renal diseases and old age predicted the most severe outcome (death or euthanasia) than any other factors.

  4. Sensory evaluation of emissions from selected building products exposed to ozone.

    Science.gov (United States)

    Knudsen, H N; Nielsen, P A; Clausen, P A; Wilkins, C K; Wolkoff, P

    2003-09-01

    The interaction of ozone with eight different building products was studied in test chambers. The products were plasterboard, two types of paints on plasterboard, two types of carpet, linoleum, pinewood, and melamine-covered particleboard. Four months of conditioning prior to the experiment had left the products with a low emission. The products' ability to remove ozone from the air covered a wide range. For three of the products (plasterboard with paint, carpet, and pinewood), it was shown that the removal was primarily due to interactions in the products' surfaces and only to a minor extent due to gas-phase reactions. Sensory evaluations were carried out for five of the products, with different ozone-removal potentials. A sensory panel assessed the emissions from sets of two specimens of each product; one specimen was exposed to a high, but realistic, ozone concentration (10 or 80 ppb) and one specimen was exposed to no ozone (background level plasterboard with paint. No clear preference was seen for melamine and linoleum.

  5. Microcapsules Filled with a Palm Oil-Based Alkyd as Healing Agent for Epoxy Matrix

    Directory of Open Access Journals (Sweden)

    Nurshafiza Shahabudin

    2016-04-01

    Full Text Available One of the approaches to prolong the service lifespan of polymeric material is the development of self-healing ability by means of embedded microcapsules containing a healing agent. In this work, poly(melamine-urea-formaldehyde (PMUF microcapsules containing a palm oil-based alkyd were produced by polymerization of melamine resin, urea and formaldehyde that encapsulated droplets of the suspended alkyd particles. A series of spherical and free-flowing microcapsules were obtained. The chemical properties of core and shell materials were characterized by Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR and proton nuclear magnetic resonance spectroscopy (1H-NMR. Differential scanning calorimetry (DSC analysis showed a glass transition around −15 °C due to the alkyd, and a melting temperature at around 200 °C due to the shell. Thermogravimetric analysis (TGA results showed that the core and shell thermally degraded within the temperature range of 200–600 °C. Field emission scanning electron microscope (FESEM examination of the ruptured microcapsule showed smooth inner and rough outer surfaces of the shell. Flexural strength and microhardness (Vickers of the cured epoxy compound were not affected with the incorporation of 1%–3% of the microcapsules. The viability of the healing reactions was demonstrated by blending small amounts of alkyd with epoxy and hardener at different ratios. The blends could readily cure to non-sticky hard solids at room temperature and the reactions could be verified by ATR-FTIR.

  6. Effects of Electrospun Carbon Nanofibers’ Interlayers on High-Performance Lithium–Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    Tianji Gao

    2017-03-01

    Full Text Available Two different interlayers were introduced in lithium–sulfur batteries to improve the cycling stability with sulfur loading as high as 80% of total mass of cathode. Melamine was recommended as a nitrogen-rich (N-rich amine component to synthesize a modified polyacrylic acid (MPAA. The electrospun MPAA was carbonized into N-rich carbon nanofibers, which were used as cathode interlayers, while carbon nanofibers from PAA without melamine was used as an anode interlayer. At the rate of 0.1 C, the initial discharge capacity with two interlayers was 983 mAh g−1, and faded down to 651 mAh g−1 after 100 cycles with the coulombic efficiency of 95.4%. At the rate of 1 C, the discharge capacity was kept to 380 mAh g−1 after 600 cycles with a coulombic efficiency of 98.8%. It apparently demonstrated that the cathode interlayer is extremely effective at shutting down the migration of polysulfide ions. The anode interlayer induced the lithium ions to form uniform lithium metal deposits confined on the fiber surface and in the bulk to strengthen the cycling stability of the lithium metal anode.

  7. Predicting time to failure in bending of wood particleboards under cyclic humidity conditions

    Directory of Open Access Journals (Sweden)

    Fernández-Golfín Seco, J. I.

    1992-03-01

    Full Text Available Time to failure tests under constant load (30, 40, 50 and 60 % stress levels were conducted on four different 19 mm thick particleboards with three layers. Two of them were uncoated (UF and MUF bonded and the rest were melamine (80 g/m2 and veneer (Mukally overlaid. Tests were carried out in cyclic humidity conditions (30 % - 90 %, at 20º C, 7 days at each condition. Time to failure was recorded, fitting mathematical models to predict time to failure. Melamine coating reduces predicting errors and increases time to failure.

    Los ensayos para observar el tiempo de rotura bajo carga constante (30, 40, 50 y 60 % de los niveles fueron llevados a cabo sobre cuatro tableros diferentes de 19 mm de espesor, constando de tres capas: dos de ellas sin recubrir (unidas mediante UF y MUF y la restante fue cubierta mediante melamina (80 g/m2 y chapada (Mukally. Los ensayos fueron realizados bajo condiciones cíclicas de humedad (30% - 90%, a 20 ºC y durante 7 días para cada caso. Se registró el tiempo de rotura, adaptándose a modelos matemáticos para predecir el tiempo de rotura. El recubrimiento con melamina reduce los errores previstos y aumenta el tiempo de rotura.

  8. INFLUENCE OF POLYMERIC ADDITIVES ON CRYSTALLIZATION OF CALCIUM SULPHATE DIHYDRATE

    Directory of Open Access Journals (Sweden)

    Ustinova Yulia Valer’evna

    2013-04-01

    Full Text Available Currently, functional additives are widely spread in the production of inorganic dry mixtures. However, their impact on the microstructure of products, generated in the process of hardening of inorganic binders, is understudied. In this context, the goal of the work is the study of calcium sulfate dihydrate (CaSO •2H O crystallization. Super plasticizer based on sulfonated melamine-formaldehyde resin, methylcellulose and vinyl acetate, ethylene and vinyl chloride copolymer powder were selected for studies. First, pure calcium sulfate dihydrate crystals were synthesized. Then, synthesized calcium sulfate dihydrate crystals were exposed to the X-ray analysis to determine the nature of influence of polymer additives on the shape and dimensions of crystals. Possible combinations of simple forms of CaSO •2H O were identified by the X-ray analysis and the special software. Electronic microscopy analysis was performed to validate models of calcium sulfate dihydrate crystals. All plasticizers influence the crystallization of calcium sulfate dihydrate. The influence of additives on the shape and dimensions of crystals of calcium sulfate dihydrate can be explained by the fact that molecules of sulfonated melamine-formaldehyde resins, methylcellulose, and copolymers of vinyl acetate, ethylene and vinyl chloride are absorbed by crystal faces. It is proven that the method of X-ray analysis can be used to predict the shape and habitus of crystals.

  9. Hydroxonium hydrate tris(2,4,6-triamino-1,3,5-triazin-1-ium bis[bis(pyridine-2,6-dicarboxylatocuprate(II] pyridine-2,6-dicarboxylic acid hexahydrate

    Directory of Open Access Journals (Sweden)

    Shabnam Hooshmand

    2009-02-01

    Full Text Available The reaction of copper(II nitrate hexahydrate with pyridine-2,6-dicarboxylic acid (pydcH2 and 2,4,6-triamino-1,3,5-triazine (melamine in aqueous solution in a 1:2:2 molar ratio gave the title compound, (H5O2(C3H7N63[Cu(C7H3NO42]2·C7H5NO4·6H2O. The hydroxonium hydrate (H5O2+, also known as the Zundel cation, resides on a twofold rotation axis. The O—H distance is 1.274 (14 Å, the O...O distance is 2.518 (5 Å, and the O—H—O angle is 162 (8°. One of the melamine H+ cations, the uncoordinated pydcH2, and two water molecules also reside on crystallographic twofold axes. The CuII atom has a tetragonally distorted octahedral coordination environment. The structure features extensive hydrogen bonding, with 21 distinct interactions. There is also a centrosymmetric C=O...π interaction with an O...centroid distance of 3.288 (3 Å. The structure is similar to a mixed-valence manganese(II/III structure but shows interesting differences in the metal-atom coordination. One of the water molecules is equally disordered with respect to a twofold axis.

  10. Photocatalytic Degradation of Anionic Azo Dyes Acid Orange 7 and Acid Red 88 in Aqueous Solutions Using TiO2-containing Hydrogel

    Directory of Open Access Journals (Sweden)

    Morteza Bahram

    2017-06-01

    Full Text Available The photocatalytic degradation of two anionic azo dyes Acid Red88 (AR 88 and Acid Orange 7 (AO7 was investigated in aqueous solution using a TiO2-containing hydrogel and UV light. The pH-sensitive hydrogel poly (styrene-alt-maleic anhydride (PSMA, was synthesized and crosslinked in the presence of melamine and TiO2 nanoparticles which results in entrapment of TiO‌2 into the melamine-grafted PSMA (M-g-PSMA hydrogel. Potential application of this nanocomposite for removal of azo dyes from wastewater was studied and the effective parameters on degradation process including time, initial pH value of the solutions, temperature and amount of added nanocomposite were optimized. The optimized values for effective parameters are as follows: time: 30 min, initial pH of the solutions: 5.23 for AO7 and 5.3 for AR88, temperature: 24 ºC and amount of added nanocomposite: 250 mg. Results showed that in optimum experimental conditions the removal percentages are about %94 for AR88 and %71 for AO7 indicating good removal performance toward the method whilst pH-sensitivity of the nanocomposite facilitates retrieval of nanocatalyst at the end of the reaction.

  11. Bis(2,4,6-triamino-1,3,5-triazin-1-ium 2-[bis(carboxylatomethylazaniumyl]acetate trihydrate

    Directory of Open Access Journals (Sweden)

    Kreshnik Hoxha

    2013-11-01

    Full Text Available The title compound, 2C3H7N6+·C6H7NO62−·3H2O, was obtained by mixing melamine and nitrilotriacetic acid in aqueous solution. There is proton transfer from the nitrilotriacteic acid to melamine to produce two melaminium cations and an internal proton transfer to generate the [HN(CH2COO]2− zwitterion. The melaminium cations are arranged in hydrogen-bonded tapes formed by N—H...N interactions. These tapes extend parallel to the [010] direction and are stacked parallel to the a axis at a mean separation of 3.3559 (11 Å. Between these tapes lie the anions and lattice water molecules. Further O—H...O and N—H...O hydrogen bonds exist between the water molecules, the anions, and the melaminium cations, generating a three-dimensional array. The crystal examined was found to be twinned by a twofold rotation about the direct lattice direction [100]. The two twin components were present in the ratio 0.5918:0.4082 (14.

  12. Commercial Gold Nanoparticles on Untreated Aluminum Foil: Versatile, Sensitive, and Cost-Effective SERS Substrate

    Directory of Open Access Journals (Sweden)

    Kristina Gudun

    2017-01-01

    Full Text Available We introduce low-cost, tunable, hybrid SERS substrate of commercial gold nanoparticles on untreated aluminum foil (AuNPs@AlF. Two or three AuNP centrifugation/resuspension cycles are proven to be critical in the assay preparation. The limits of detection (LODs for 4-nitrobenzenethiol (NBT and crystal violet (CV on this substrate are about 0.12 nM and 0.19 nM, respectively, while maximum analytical SERS enhancement factors (AEFs are about 107. In comparative assays LODs for CV measured on AuNPs@Au film and AuNPs@glass are about 0.35 nM and 2 nM, respectively. The LOD for melamine detected on AuNPs@ Al foil is 27 ppb with 3 orders of magnitude for linear response range. Overall, AuNPs@AlF demonstrated competitive performance in comparison with AuNPs@ Au film substrate in SERS detection of CV, NBT, and melamine. To check the versatility of the AuNPs@AlF substrate we also detected KNO3 with LODs of 0.7 mM and SERS EF around 2 × 103, which is on the same order with SERS EF reported for this compound in the literature.

  13. Catalytic performance of heterogeneous Rh/C3N4 for the carbonylation of methanol

    Science.gov (United States)

    Budiman, Anatta Wahyu; Choi, Myoung Jae; Nur, Adrian

    2018-02-01

    The excess of water in homogeneous the carbonylation of methanol system could increase the amount of by-products formed through water-gas shift reaction and could accelerate the rusting of equipment. Many scientists tried to decrease the content of water in the carbonylation of methanol system by using lithium and iodide promoter that results a moderate catalytic activity in the water content at 2wt%. The heterogenized catalyst offers several distinct advantages such as it was enables increased catalyst concentration in the reaction mixture, which is directly proportional to acetic acid production rate, without the addition of an alkali iodide salt promoter. The heterogeneous catalyst also results in reduced by-product formation. This study is aimed to produce a novel catalyst (Rh/C3N4) with a high selectivity of acetic acid in a relatively lower water and halide content. This novel catalyst performs high conversion and selectivity of acetic acid as the result of the strong ionic bonding of melamine and rhodium complex species that was caused by the presence of methyl iodide species. The CO2 in feed gas significantly decreases the catalytic activity of Rh-melamine because of its inert characteristics. The kinetic test was performed as that the first order kinetic equation. The kinetic tests revealed the reaction route of the the carbonylation of methanol in this system was performed trough the methyl acetate.

  14. Facile preparation of three-dimensional Co1-xS/sulfur and nitrogen-codoped graphene/carbon foam for highly efficient oxygen reduction reaction

    Science.gov (United States)

    Liang, Hui; Li, Chenwei; Chen, Tao; Cui, Liang; Han, Jingrui; Peng, Zhi; Liu, Jingquan

    2018-02-01

    Because of the urgent need for renewable resources, oxygen reduction reaction (ORR) has been widely studied. Finding efficient and low cost non-precious metal catalyst is increasingly critical. In this study, melamine foam is used as template to obtain porous sulfur and nitrogen-codoped graphene/carbon foam with uniformly distributed cobalt sulfide nanoparticles (Co1-xS/SNG/CF) which is prepared by a simple infiltration-drying-sulfuration method. It is noteworthy that melamine foam not only works as a three-dimensional support skeleton, but also provides a nitrogen source without any environmental pollution. Such Co1-xS/SNG/CF catalyst shows excellent oxygen reduction catalytic performance with an onset potential of only 0.99 V, which is the same as that of Pt/C catalyst (Eonset = 0.99 V). Furthermore, the stability and methanol tolerance of Co1-xS/SNG/CF are more outstanding than those of Pt/C catalyst. Our work manifests a facile method to prepare S and N-codoped 3D graphene network decorated with Co1-xS nanoparticles, which may be utilized as potential alternative to the expensive Pt/C catalysts toward ORR.

  15. Quantitative analysis of hindered amine light stabilizers by CZE with UV detection and quadrupole TOF mass spectrometric detection.

    Science.gov (United States)

    Hintersteiner, Ingrid; Schmid, Thomas; Himmelsbach, Markus; Klampfl, Christian W; Buchberger, Wolfgang W

    2014-10-01

    The current work describes the development of a CZE method with quadrupole QTOF-MS detection and UV detection for the quantitation of Cyasorb 3529, a common hindered amine light stabilizer (HALS), in polymer materials. Analysis of real polymer samples revealed that the oligomer composition of Cyasorb 3529 changes during processing, a fact hampering the development of a straightforward method for quantitation based on calibration with a Cyasorb 3529 standard. To overcome this obstacle in-depth investigations of the oligomer composition of this HALS using QTOF-MS and QTOF-MS/MS had to be performed whereby 22 new oligomer structures, in addition to the ten structures already described, were identified. Finally, a CZE method for quantitative analysis of this HALS was developed starting with a comprehensive characterization of a Cyasorb 3529 standard using CZE-QTOF-MS, subsequently allowing the correct assignment of most Cyasorb 3529 oligomers in an electropherogram with UV detection. Employing the latter detection technique and hexamethyl-melamine as internal standard, peak areas obtained for the melamine could be correlated with those from the triazine ring, the UV-absorbing unit present in the HALS. This approach finally allowed proper quantitation of the single oligomers of Cyasorb 3529, an imperative for the quantitative assessment of this HALS in real polymer samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Single-Drop Raman Imaging Exposes the Trace Contaminants in Milk.

    Science.gov (United States)

    Tan, Zong; Lou, Ting-Ting; Huang, Zhi-Xuan; Zong, Jing; Xu, Ke-Xin; Li, Qi-Feng; Chen, Da

    2017-08-02

    Better milk safety control can offer important means to promote public health. However, few technologies can detect different types of contaminants in milk simultaneously. In this regard, the present work proposes a single-drop Raman imaging (SDRI) strategy for semiquantitation of multiple hazardous factors in milk solutions. By developing SDRI strategy that incorporates the coffee-ring effect (a natural phenomenon often presents in a condensed circle pattern after a drop evaporated) for sample pretreatment and discrete wavelet transform for spectra processing, the method serves well to expose typical hazardous molecular species in milk products, such as melamine, sodium thiocyanate and lincomycin hydrochloride, with little sample preparation. The detection sensitivity for melamine, sodium thiocyanate, and lincomycin hydrochloride are 0.1 mg kg -1 , 1 mg kg -1 , and 0.1 mg kg -1 , respectively. Theoretically, we establish that the SDRI represents a novel and environment-friendly method that screens the milk safety efficiently, which could be well extended to inspection of other food safety.

  17. Cobalt-doped graphitic carbon nitride photocatalysts with high activity for hydrogen evolution

    Science.gov (United States)

    Chen, Pei-Wen; Li, Kui; Yu, Yu-Xiang; Zhang, Wei-De

    2017-01-01

    Cobalt-doped graphitic carbon nitride (Cosbnd CN) was synthesized by one-step thermal polycondensation using cobalt phthalocyanine (CoPc) and melamine as precursors. The π-π interaction between melamine and CoPc promotes cobalt doping into the framework of g-C3N4. The prepared samples were carefully characterized and the results demonstrated that Co-doped graphitic carbon nitride inhibited the crystal growth of graphitic carbon nitride (CN), leading to larger specific surface area (33.1 m2 g-1) and abundant Co-Nx active sites, narrower band gap energy and more efficient separation of photogenerated electrons and holes. 0.46% Cosbnd CN exhibited higher hydrogen evolution rate (28.0 μmol h-1) under visible light irradiation, which is about 3.0 times of that over the pure CN and about 2.2 times of that over cobalt-doped CN using CoCl2 • 6H2O as a cobalt source. This study provides a valuable strategy to modify CN with enhanced photocatalytic performance.

  18. Thermal neutron capture cross section of chromium, vanadium, titanium and nickel isotopes

    International Nuclear Information System (INIS)

    Venturini, L.; Pecequilo, B.R.S.

    1990-04-01

    The thermal neutron cross section of chromium, vanadium, titanium and nickel can be determined by measuring the pair spectrum of prompt gamma-rays emitted targets of these elements are irradiated by a thermal neutron beam. Such measurements were carried out by irradiating the natural element mixed with a nitrogen standard (melamine) in the tangential beam hole of the IEA-R1 research reactor. The pair spectrometer efficiency calibration curve in the 1.5 to 11 MeV energy range was performed with a melamine plus ammonium chloride mixed target. The cross section was calculated for the most prominent gamma transitions of each isotope, using nitrogen as standard and averaged over the obtained values. The resulting mean cross sections are as follows: (13.4 ± 0.7)b for 50 Cr, (0.79 ± 0,02)b for 52 Cr, (18.1 ± 0,7)b for 53 Cr, (4.9 ± 0.2)b for 51 V, (8.4 ± 0.1)b for 48 Ti, (4.41 ± 0.08)b 58 Ni, (2.54 ± 0.07)b for 60 Ni, (15.2 ± 0.5)b for 62 Ni and (1.6 ± 0.1) for 64 Ni. (author) [pt

  19. Sulfur-Modified Graphitic Carbon Nitride Nanostructures as an Efficient Electrocatalyst for Water Oxidation.

    Science.gov (United States)

    Kale, Vinayak S; Sim, Uk; Yang, Jiwoong; Jin, Kyoungsuk; Chae, Sue In; Chang, Woo Je; Sinha, Arun Kumar; Ha, Heonjin; Hwang, Chan-Cuk; An, Junghyun; Hong, Hyo-Ki; Lee, Zonghoon; Nam, Ki Tae; Hyeon, Taeghwan

    2017-05-01

    There is an urgent need to develop metal-free, low cost, durable, and highly efficient catalysts for industrially important oxygen evolution reactions. Inspired by natural geodes, unique melamine nanogeodes are successfully synthesized using hydrothermal process. Sulfur-modified graphitic carbon nitride (S-modified g-CN x ) electrocatalysts are obtained by annealing these melamine nanogeodes in situ with sulfur. The sulfur modification in the g-CN x structure leads to excellent oxygen evolution reaction activity by lowering the overpotential. Compared with the previously reported nonmetallic systems and well-established metallic catalysts, the S-modified g-CN x nanostructures show superior performance, requiring a lower overpotential (290 mV) to achieve a current density of 10 mA cm -2 and a Tafel slope of 120 mV dec -1 with long-term durability of 91.2% retention for 18 h. These inexpensive, environmentally friendly, and easy-to-synthesize catalysts with extraordinary performance will have a high impact in the field of oxygen evolution reaction electrocatalysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. One-step synthesis of shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond as efficient electrocatalyst for the oxygen reduction reaction in alkaline media

    International Nuclear Information System (INIS)

    Liu, Xiaoxu; Wang, Yanhui; Dong, Liang; Chen, Xi; Xin, Guoxiang; Zhang, Yan; Zang, Jianbing

    2016-01-01

    Shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond (BN-C/ND) non-noble metal catalyst has been synthesized by a simple one-step heat-treatment of the mixture with nanodiamond, melamine, boric acid and FeCl 3 . In the process of the surface graphitization of nanodiamond with catalysis by FeCl 3 , B and N atoms from the decomposition of boric acid and melamine were directly introduced into the graphite lattice to form B, N co-doped graphitic carbon shell, while the core still retained the diamond structure. Electrochemical measurements of the BN-C/ND catalyst show much higher electrocatalytic activities towards oxygen reduction reaction (ORR) in alkaline medium than its analogues doped with B or N alone (B-C/ND or N-C/ND). The high catalytic activity of BN-C/ND is attributed to the synergetic effect caused by co-doping of C/ND with B and N. Meanwhile, the BN-C/ND exhibits an excellent electrochemical stability due to the special shell/core structure. There is almost no alteration occurred in the cyclic voltammetry measurements for BN-C/ND before and after 5000 cycles. All experimental results prove that the BN-C/ND may be exploited as a potentially efficient and inexpensive non-noble metal cathode catalyst for ORR to substitute Pt-based catalysts in fuel cells.

  1. DFT Perspective on the Thermochemistry of Carbon Nitride Synthesis

    KAUST Repository

    Melissen, Sigismund T. A. G.

    2016-10-11

    Graphitic (g)-CxNyHz has become a popular family of photoharvesters in photocatalytic water splitting cells, as well as other applications in chemistry. In this Article, different g-CxNyHz structures were studied thermochemically using DFT. Following a benchmark study with different families of functionals, the B3LYP functional was shown to accurately capture the thermochemistry of carbon nitride synthesis. A triple-ζ polarized basis set, in combination with Civalleri’s modification to Grimme’s D2 formalism (with s6 = 0.5) for dispersion interactions, yielded accurate geometries. Grimme’s D3 formalism with Becke–Johnson damping was used to refine the energetic description of dispersion interactions. The stepwise cycloaddition of cyanamide to form melamine was shown to be exergonic, whereas the stepwise deamination of melamine to form g-C3N4 was shown to be endergonic. Of those structures respecting the [C6N9H3]n chemical formula, the structure commonly known as “melon” was found to be most stable, whereas the sp3-hybridized [C6N9H3]n elucidated by Horvath-Bordon et al. was found to be the least stable. Fully polymerized triazine-based g-C3N4 appeared slightly more stable than heptazine-based g-C3N4.

  2. In situ hydrothermal synthesis of g-C{sub 3}N{sub 4}/TiO{sub 2} heterojunction photocatalysts with high specific surface area for Rhodamine B degradation

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Ruirui [Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Institute for Advanced Materials, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002 (China); Wang, Guohong, E-mail: wanggh2003@163.com [Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Institute for Advanced Materials, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002 (China); Jiang, Chuanjia [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan, 430070 (China); Tang, Hua [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, 212013 (China); Xu, Qingchuan [Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Institute for Advanced Materials, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002 (China)

    2017-07-31

    Highlights: • High surface area g-C{sub 3}N4/TiO{sub 2} is obtained by combined hydrothermal-calcination method. • HCl formation from Ti precursor changed the structural properties of the composite. • Composite exhibited visible light photocatalytic performance for RhB degradation. • A 3 g of melamine for 0.5 mL TiCl{sub 4} was found to be the optimum content. - Abstract: Semiconductor-based photocatalysis is a promising method for degradation of environmental pollutants, but the activity of most widely used photocatalysts such as titania (TiO{sub 2}) is still unsatisfactory under visible light. Herein, we synthesized a highly efficient visible-light-responsive heterojunction catalysts based on graphitic carbon nitride (g-C{sub 3}N{sub 4}) and TiO{sub 2}. The g-C{sub 3}N{sub 4}/TiO{sub 2} heterojunction composites with high specific surface area were prepared via in situ hydrothermal synthesis followed by calcination, using titanium tetrachloride (TiCl{sub 4}) and melamine as precursors. Interesting, HCl from the hydrolysis of TiCl{sub 4} served as the proton source to acidify the melamine. The g-C{sub 3}N{sub 4}/TiO{sub 2} heterojunction composites exhibited higher photocatalytic performance for decomposition of Rhodamine B (RhB) than pure g-C{sub 3}N{sub 4} or TiO{sub 2} under visible light irradiation. The high activity can be ascribed to the high specific surface area (up to 115.6 m{sup 2} g{sup −1}) of the g-C{sub 3}N{sub 4}/TiO{sub 2} composites and a synergistic heterojunction structure between TiO{sub 2} and g-C{sub 3}N{sub 4}. Moreover, the photocatalytic performances of the g-C{sub 3}N{sub 4}/TiO{sub 2} composites rely on the content of melamine in the synthesis precursors: with an optimum melamine content (3 g for 0.5 mL of TiCl{sub 4}), the sample showed the highest photocatalytic performance, which is superior to pure TiO{sub 2} and g-C{sub 3}N{sub 4} by a factor of 18.7 and 3.5, respectively. Active species trapping experiments revealed that

  3. [Identification of adulterants in adulterated milks by near infrared spectroscopy combined with non-linear pattern recognition methods].

    Science.gov (United States)

    Ni, Li-Jun; Zhong, Lin; Zhang, Xin; Zhang, Li-Guo; Huang, Shi-Xinz

    2014-10-01

    In the present work, two hundred and eighty seven raw milks collected from pastures in Shanghai and surrounding areas of Shanghai were used as true milk samples and divided into three true milk sets. Five hundred and twenty six adulterated milk samples, which contained dextrin (or starch) mixed with melamine (or urea, or ammonium nitrate), were prepared as six different adulterated milk sets. The concentrations of these adulterants in the adulterated milks were designed to be 0.15%~ 0.45% (starch or dextrin), 700-2,100 mg · kg(-1) (ammonium nitrate), 524-1,572 mg · kg(-1) (urea), and 365.5-1,096.5 mg · kg(-1) (melamine) to guarantee the protein content of adulterated milks detected by Kjeldahl method not lower than 3%. All the near infrared spectra (NIR) of the samples should have a pretreatment of normal variable transformation (SNV) before they were used to build discriminating models. The three true milk sets and six adulterated milk sets were combined in different ways in order to build NIR models for discriminating different kinds of adulterants (i. e. , dextrin, starch, melamine, urea and ammonium nitrate) based on simplified K-nearest neighbor classification algorithm (IS-KNN) and an improved and simplified of support vector machine (ν-SVM) method. The relationship between mass concentration of the adulterants and the rate of correct discrimination was also investigated. The results show that the average discrimination accuracy of IS-KNN and ν-SVM for identifying melamine, urea and ammonium nitrate were in the region of 49.55% to 51.01%, 61.78% to 68.79% and 68.25% to 73.51%, respectively. Therefore within the concentration regions designed in this study, it is difficult to distinguish different kinds of pseudo proteins by NIR spectroscopy. However, the average accuracy of IS-KNN and ν-SVM for identifying starch and dextrin are 92.33% and 93.66%, 77.29% and 85.08%, respectively. Most discrimination results of ν-SVM are better than those of IS-KNN. The

  4. Facile fabrication of ordered mesoporous graphitic carbon nitride for RhB photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Lei; Zhang, Anfeng [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Janik, Michael J. [EMS Energy Institute, PSU-DUT Joint Center for Energy Research and Department of Energy & Mineral Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Li, Keyan [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Song, Chunshan [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); EMS Energy Institute, PSU-DUT Joint Center for Energy Research and Department of Energy & Mineral Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Guo, Xinwen, E-mail: guoxw@dlut.edu.cn [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2017-02-28

    Highlights: • Ordered mesoporous graphitic carbon nitrides with S{sub BET} = 279.3 m{sup 2}/g were prepared. • Enhanced photocatalytic activity and reusability were presented. • Improved S{sub BET} and charge carrier separation efficiency contribute to the activity. - Abstract: Ordered mesoporous graphitic carbon nitrides were prepared by directly condensing the uniform mixtures of melamine and KIT-6. After removal of the KIT-6 sacrificial template, the carbon nitrides were characterized with TEM, N{sub 2} physical adsorption, XRD, FT-IR, XPS, UV–vis and PL spectrometries, and tested for their RhB photocatalytic degradation activity. Together, these characterizations confirmed the as-prepared tunable mesoporous materials with enhanced charge separation efficiency and superior photocatalytic performance. Compared with a conventional bulk g-C{sub 3}N{sub 4}, ordered mesoporous g-C{sub 3}N{sub 4} exhibits a larger specific surface area of 279.3 m{sup 2}/g and a pore size distribution about 4.0 nm and 13.0 nm. Meanwhile, the reduced bandgap energy of 2.77 eV and lower photogenerated electron-hole pair recombination frequency were evidenced by UV–Vis and PL spectra. The RhB photocatalytic degradation activity maximizes with a mass ratio of KIT-6/melamine of 80% (KCN80), and the kinetic constant reaches 0.0760 min{sup −1} which is 16 times higher than that of the bulk sample. Reusability of KCN80 was demonstrated by a lack of evident deactivation after three consecutive reaction periods. The direct condensation of the KIT-6 and melamine mixture does not require pre-casting of the precursor into the pore system of the templates. Owing to its high product yield, improved S{sub BET}, reduced bandgap energy and limited charge recombination, the facile-prepared ordered mesoporous g-C{sub 3}N{sub 4} is a practical candidate for further modification.

  5. Effects of calcining temperature on photocatalysis of g-C{sub 3}N{sub 4}/TiO{sub 2} composites for hydrogen evolution from water

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Ailan, E-mail: elainqal@163.com; Xu, Xinmei; Xie, Haolong; Zhang, Yangyu; Li, Yuyu; Wang, Junxian

    2016-08-15

    Highlights: • TiO{sub 2} promotes melon to form at 400 °C, whereas it forms at 500 °C for only melamine. • The highest photocatalytic activity was achieved when calcination was performed at 400 °C. • Coordinated N−Ti−N bonds were formed in MA/TiO{sub 2} (400) and disappeared at high temperature. • The surface area decreased and the pore size increased with increasing of temperature. • Only MA/TiO{sub 2} (400) has a narrower band gap than pure g-C{sub 3}N{sub 4}. - Abstract: A composite of graphitic carbon nitride and TiO{sub 2} (g-C{sub 3}N{sub 4}/TiO{sub 2}) with enhanced photocatalytic hydrogen evolution capacity was achieved by calcining melamine and TiO{sub 2} sol-gel precursor. Characterization results reveal that heating temperature had a great influence on the structure, surface area and properties of the composites. Compared with the polycondensation of pure melamine, the presence of TiO{sub 2} precursor can promote the formation of melon at a low temperature. The highest photocatalytic activity of g-C{sub 3}N{sub 4}/TiO{sub 2}(400) was achieved when the calcination was performed at 400 °C, exhibiting H{sub 2} production rate of 76.25 μmol/h under UV–vis light irradiation (λ > 320 nm) and 35.44 μmol/h under visible light irradiation (λ > 420 nm). The highest photocatalytic performance of g-C{sub 3}N{sub 4}/TiO{sub 2}(400) can be attributed to: (1) the strong UV–vis light absorption due to the narrow bandgap caused by synergic effect of TiO{sub 2} and g-C{sub 3}N{sub 4}, (2) high surface area and porosity, (3) the effective separation of photo-generated electron-holes owing to the favorable heterojunction between TiO{sub 2} and g-C{sub 3}N{sub 4}.

  6. Food Safety: At the Center of a One Health Approach for Combating Zoonoses

    DEFF Research Database (Denmark)

    Wielinga, Pieter; Schlundt, Jørgen

    2013-01-01

    outbreaks over dioxin crises to intentional melamine contamination. One Health formulates clearly both the need for and the benefit of cross-sectoral collaboration. In this chapter, we will focus on the human health risk related to zoonotic microorganisms present both in food animals and food from...... international organizations and national agricultural-and health authorities in most countries, for instance as was the case with avian influenza. Other diseases relate to the industrialized food production chain and have been-in some settings-dealt with efficiently through farm-to-fork preventive action......Food Safety is at the center of One Health. Many, if not most, of all important zoonoses relate in some way to animals in the food production chain. Therefore, the food becomes an important vehicle for many, but not all, of these zoonotic pathogens. One of the major issues in food safety over...

  7. Photocatalytic activities of coke carbon/g-C3N4 and Bi metal/Bi mixed oxides/g-C3N4 nanohybrids for the degradation of pollutants in wastewater

    OpenAIRE

    Sierra, Marta; Borges, Emma; Esparza, Pedro; M?ndez-Ramos, Jorge; Mart?n-Gil, Jes?s; Mart?n-Ramos, Pablo

    2016-01-01

    Abstract Different g-C3N4 composite systems (coke carbon/g-C3N4, Bi/Bi2WO6/g-C3N4 and Bi/Bi2MoO6/g-C3N4) have been assessed as photocatalysts for wastewater pollutants removal. The coke carbon/g-C3N4 hybrid, produced by thermal treatment at 550??C of a composite made from melamine cyanurate and coke, only showed activity under UV-light irradiation. On the other hand, inorganic Bi spheres/Bi mixed oxides/g-C3N4 nanohybrids (Bi/Bi2WO6/g-C3N4 and Bi/Bi2MoO6/g-C3N4 composites), produced by therma...

  8. Facile Preparation of g-C3N4 Modified BiOCl Hybrid Photocatalyst and Vital Role of Frontier Orbital Energy Levels of Model Compounds in Photoactivity Enhancement

    OpenAIRE

    Shi, S.; Gondal, M.A.; Al-Saadi, A.A.; Fajgar, R. (Radek); Kupčík, J. (Jaroslav); Chang, X.; Shen, K.; Xu, Q.; Seddigi, Z.S.

    2014-01-01

    A novel hybrid photocatalyst (g-C3N4/BiOCl) using g-C3N4 series modified with BiOCl having controllable mass ratios among the g-C3N4 and BiOCl molecules was prepared through hydrolysis process of Bi3+ onto g-C3N4, using NaBiO3 and g-C3N4 produced from pyrolysis of melamine as the starting materials. The microstructure, morphology and optical properties of the synthesized g-C3N4/BiOCl were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis diffuse reflectio...

  9. Effect of MUF/Epoxy Microcapsules on Mechanical Properties and Fractography of Epoxy Materials

    Science.gov (United States)

    Ni, Zhuo; Lin, Yuhao; Du, Xuexiao

    2017-12-01

    Melamine-urea-formaldehyde (MUF) microcapsules were synthesized, morphology, shell thickness, average diameter and interface morphology were studied by scanning electron microscope (SEM). The spherical MUF microcapsules are size normal distribution without adhesion and accumulation, being compact, rough and uneven with a thickness of 3.2μm and a core contents is approximate 70%. A latent imidazoleas the curing agent for a cross-linking chemical reaction for cracking repairing. A good dispersion of MUF microcapsules and a good interfacial bonding are obtained. Effects of MUF microcapsule size and content on bending property and dynamic mechanical propertywere investigated. Both bending strength and storage modulus of the composite are considerably reduced with an increasing addition of the microcapsules whereas the glass transition temperatures are almost not influenced. Significant toughening effects of MUF microcapsules on the epoxy composites are observed at the conditions of different content and size of microcapsule especially at low microcapsule contents and small microcapsule sizes.

  10. Comparision between different metal oxide nanostructures and nanocomposites for sensing, energy generation, and energy harvesting

    Science.gov (United States)

    Willander, Magnus; Alnoor, Hatim; Elhag, Sami; Ibupoto, Zafar Hussain; Nour, Eiman Satti; Nur, Omer

    2016-02-01

    Highlights from research on different nanocomposites and nanostructures for sensing and other energy related applications will be presented. The synthesized nanostructures and nanocomposites presented here were all obtained using the low temperature (textile and paper. We here present results from different metal oxide nanostructures employed for chemical sensing and some innovative energy related applications. Efficient sensitive and selective sensing of dopamine, melamine, and glucose are presented as some examples of self-powered sensors utilizing the electrochemical phenomenon i.e. transferring chemical energy into electrical signal. Further the use of nanomaterials for developing selfpowered devices utilizing mechanical ambient energy is presented via piezoelectric and triboelectric effects. Here the self-powered devices and systems were relying on utilizing the electormechanical phenomenon i.e. transferring ambient mechanical energy into useful electrical energy. Finally the visibility of nanomaterials prepared by the low temperature chemical synthesis as possible low cost replacement of Pt electrodes for hydrogen production is briefly presented and discussed.

  11. Determination of the resistance of fabric printed with triclosan microcapsules to the action of soil micro-flora

    Science.gov (United States)

    Golja, B.; Forte Tavčer, P.

    2017-10-01

    Microcapsules with a pressure-sensitive melamine-formaldehyde wall and triclosan core were printed to 100% cotton fabric with screen printing technique. Previous research showed excellent antibacterial activity (estimated for E. Coli and S. Aureus) of such fabric, so our aim in this research was to determine its resistance to the action of microorganisms present in the soil. The soil burial test was conducted. The breaking strength of the buried samples was measured and also the scanning electron microscope analysis was done. The results showed that none of the samples are resistant to decay. It is evident from SEM micrographs that on all of the buried samples greater morphological changes occur due to the functions of the soil microflora. It can be concluded that the samples printed with triclosan microcapsules are biodegradable which is environmentally preferable.

  12. 350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Matouq, Faris A.; Khiari, F.Z.; Gondal, M.A.; Rehman, Khateeb-ur [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Isab, A.A. [Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Raashid, M.; Dastageer, M.A. [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2013-11-21

    Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53–3.68, 4.51, 5.27–5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

  13. Erection of duct-like graphitic carbon nitride with enhanced photocatalytic activity for ACB photodegradation

    Science.gov (United States)

    Muhmood, Tahir; Xia, Mingzhu; Lei, Wu; Wang, Fengyun

    2018-02-01

    Novel duct graphitic carbon nitride (DCN) was successfully prepared using the temperature control method in a quartz tube furnace from commercially available melamine and evaluated against the photo-degradation of latent organic pollutants, acarbose (ACB). These prepared materials were characterized by UV-Vis spectroscopy, Fourier transform infrared spectra, x-ray photoelectron spectroscopy, x-ray diffraction, transmission electron microscopy and scanning electron microscopy. The characterization results indicated that the synthesized material was in the form of a duct-like structure and has greater adsorption capacity and photocatalytic ability as compared to traditionally synthesized graphitic carbon nitride materials. The DCN split theACB completely into many intermediates, which were depicted in the HPLC-MS spectrum for knowing the acarbose photo-degrdation pathway. The duct-like morphology of graphitic carbon nitride has improved properties, such as increasing the surface area and decelerating the e -/h + recombination, which increase the light absorbance ability with enhanced photoactivity.

  14. Radiation hardening lacquer binding agent based on a polyester resin with at least 3.5 double links pr. 1000 molecular weight units

    International Nuclear Information System (INIS)

    Crimlisk, D.J.; Wright, A.; Groves, T.E.

    1976-01-01

    The binding agent is suitable for hardening by electrons with an energy of between 100,000 and 500,000eV. It consists mainly of a solution of a polyester resin with at least 3.5 double links per 1000 mol, in an olefine-unsaturated monomer. The molecular weight of the polyester is between 800 and 1100 and the ratio of the number of double links in the monomer to that in the resin (degree of unsaturation) is in the range 0.75-2.0, or more specifically, between 1 and 1.5. Cellulose acetate/butyrate (CAB) and/or a butylated melamine/formaldehyde resin may be added to improve the surface properties. Likewise from 0.1 to 0.5% polyethylene wax may be added to give a better surface finish and hardness. (JIW)

  15. Modification of poly(styrene-block-butadiene-block-styrene) [SBS] with phosphorus containing fire retardants

    DEFF Research Database (Denmark)

    Chernyy, Sergey; Ullah, Saif; Jomaas, Grunde

    2015-01-01

    An elaborate survey of the chemical modification methods for endowing highly flammable SBS with increased fire resistant properties by means of chemical modification of the polymer backbone with phosphorus containing fire retardant species is presented. Optimal conditions for free radical addition...... resulting in 20 mol% of poly(butadiene) block modification. Based on TGA results, organophosporus-modified SBS was found to be amenable to charring – a property which correlated directly with the reduced flammability of the modified polymer observed in Cone Calorimetry tests. Furthermore, conceptually novel...... application of the H3PO4 modified SBS as a fire retardant additive for bitumen material, in combination with synergetic melamine species, offered 25% better self-extinguishing properties of such formulation already at a low loading level of the fire retardant components (3.5 wt.%)....

  16. Heat storage characteristics of latent microcapsules using hot air bubbles by direct contact heat exchange; Onshitsu kihogun to sennetsu microcapsule tono chokusetsu sesshohku kokan ni yoru chikunetsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, K.; Sugiura, T. [Toyohashi University of Technology, Aichi (Japan)

    2000-05-25

    This paper has dealt with the heat storage characteristics of fine microcapsules packed with latent heat storage material in the water layer. The heat storage operation to the latent microcapsules was carried out using hot air bubbles by direct contact heat exchange. The microcapsule consists of n-paraffin as a core latent-heat storage material and melamine resin as a coating substance. The relation of the completion time of latent-heat storage to some parameters was examined experimentally. The non-dimensional correlation equations for the completion time of latent-heat storage process had were derived in terms of the ratio of water layer height to diameter of microcapsule, Reynolds number for air flow, Stefan number and modified Stefan number for absolute humidity of flowing air. (author)

  17. A Study of UV Resistance of a Water-based Polyurethane Lacquer Containing Nano Ceria

    Directory of Open Access Journals (Sweden)

    Arash Saadat-Monfared

    2013-01-01

    Full Text Available Cerium oxide (Ceria nano particle, as photodegradation prevention agent was studied in water-based polyurethane clear coat  systems. Polyurethane coatings show superior weathering resistance compared with acrylic melamine systems. However, any chemical change has detrimental effects on the property profile of PU coatings. Coatings containing various amounts of cerium oxide nanoparticles were prepared and their weathering resistance was evaluated using simulated UV cabinet. To this end the extent and mechanism of degradation was studied utilizing UV-Vis and FTIR-ATR spectroscopy as well as DMTA analysis. The results revealed that Ceria nano particles with concentration of 1.44 % (wt absorb beyond 92.5% of UV light of UV-B region and showed an efficiency of 2000 times as of organic UV absorbers.

  18. Raman spectroscopy as an effective screening method for detecting adulteration of milk with small nitrogen-rich molecules and sucrose.

    Science.gov (United States)

    Nieuwoudt, M K; Holroyd, S E; McGoverin, C M; Simpson, M C; Williams, D E

    2016-04-01

    Adulteration of milk for commercial gain is acknowledged as a serious issue facing the dairy industry. Several analytical techniques can be used to detect adulteration but they often require time-consuming sample preparation, expensive laboratory equipment, and highly skilled personnel. Here we show that Raman spectroscopy provides a simple, selective, and sensitive method for screening milk, specifically for small nitrogen-rich compounds, such as melamine, urea, ammonium sulfate, dicyandiamide, and for sucrose. Univariate and multivariate statistical methods were used to determine limits of detection and quantification from Raman spectra of milk spiked with 50 to 1,000 mg/L of the N-rich compounds and 0.25 to 4% sucrose. Partial least squares (PLS) calibration provided limit of detection minimum thresholds milk for these adulterants. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  19. Development of a Raman chemical image detection algorithm for authenticating dry milk

    Science.gov (United States)

    Qin, Jianwei; Chao, Kuanglin; Kim, Moon S.

    2013-05-01

    This research developed a Raman chemical imaging method for detecting multiple adulterants in skim milk powder. Ammonium sulfate, dicyandiamide, melamine, and urea were mixed into the milk powder as chemical adulterants in the concentration range of 0.1-5.0%. A Raman imaging system using a 785-nm laser acquired hyperspectral images in the wavenumber range of 102-2538 cm-1 for a 25×25 mm2 area of each mixture. A polynomial curve-fitting method was used to correct fluorescence background in the Raman images. An image classification method was developed based on single-band fluorescence-free images at unique Raman peaks of the adulterants. Raman chemical images were created to visualize identification and distribution of the multiple adulterant particles in the milk powder. Linear relationship was found between adulterant pixel number and adulterant concentration, demonstrating the potential of the Raman chemical imaging for quantitative analysis of the adulterants in the milk powder.

  20. Simultaneous detection of multiple adulterants in dry milk using macro-scale Raman chemical imaging.

    Science.gov (United States)

    Qin, Jianwei; Chao, Kuanglin; Kim, Moon S

    2013-06-01

    The potential of Raman chemical imaging for simultaneously detecting multiple adulterants in milk powder was investigated. Potential chemical adulterants, including ammonium sulphate, dicyandiamide, melamine, and urea, were mixed together into skim dry milk in the concentration range of 0.1-5.0% for each adulterant. Using a 785-nm laser, a Raman imaging system acquired hyperspectral images in the wavenumber range of 102-2538 cm(-1) for a 25 × 25 mm(2) area of each mixture sample, with a spatial resolution of 0.25 mm. Self-modelling mixture analysis (SMA) was used to extract pure component spectra, by which the four types of the adulterants were identified at all concentration levels based on their spectral information divergence values to the reference spectra. Raman chemical images were created using the contribution images from SMA, and their use to effectively visualise identification and spatial distribution of the multiple adulterant particles in the dry milk was demonstrated. Published by Elsevier Ltd.

  1. Recent advances on determination of milk adulterants.

    Science.gov (United States)

    Nascimento, Carina F; Santos, Poliana M; Pereira-Filho, Edenir Rodrigues; Rocha, Fábio R P

    2017-04-15

    Milk adulteration is a current fraudulent practice to mask the quality parameters (e.g. protein and fat content) and increase the product shelf life. Milk adulteration includes addition of toxic substances, such as formaldehyde, hydrogen peroxide, hypochlorite, dichromate, salicylic acid, melamine, and urea. In order to assure the food safety and avoid health risks to consumers, novel analytical procedures have been proposed for detection of these adulterants. The innovations encompass sample pretreatment and improved detection and data processing, including chemometric tools. This review focuses on critical evaluation of analytical approaches for assay of milk adulteration, with emphasis on applications published after 2010. Alternatives for fast, environmentally friendly and in-situ detection of milk adulterants are highlighted. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Optical nanoparticles: synthesis and biomedical application

    Science.gov (United States)

    Nhung Tran, Hong; Nghiem, Thi Ha Lien; Thuy Duong Vu, Thi; Chu, Viet Ha; Huan Le, Quang; Nhung Hoang, Thi My; Thanh Nguyen, Lai; Pham, Duc Minh; Thuan Tong, Kim; Hoa Do, Quang; Vu, Duong; Nghia Nguyen, Trong; Tan Pham, Minh; Nguyen Duong, Cao; Thuy Tran, Thanh; Son Vu, Van; Thuy Nguyen, Thi; Nguyen, Thi Bich Ngoc; Tran, Anh Duc; Thuong Trinh, Thi; Nguyen, Thi Thai An

    2015-01-01

    This paper presents a summary of our results on studies of synthesis and biomedical application of optical nanoparticles. Gold, dye-doped silica based and core-shell multifunctional multilayer (SiO2/Au, Fe3O4/SiO2, Fe3O4/SiO2/Au) water-monodispersed nanoparticles were synthesized by chemical route and surface modified with proteins and biocompatible chemical reagents. The particles were conjugated with antibody or aptamer for specific detecting and imaging bacteria and cancer cells. The photothermal effects of gold nanoshells (SiO2/Au and Fe3O4/SiO2/Au) on cells and tissues were investigated. The nano silver substrates were developed for surface enhanced Raman scattering (SERS) spectroscopy to detect melamine.

  3. Preparation of Flame Retardant Modified with Titanate for Asphalt Binder

    Directory of Open Access Journals (Sweden)

    Bo Li

    2014-01-01

    Full Text Available Improving the compatibility between flame retardant and asphalt is a difficult task due to the complex nature of the materials. This study explores a low dosage compound flame retardant and seeks to improve the compatibility between flame retardants and asphalt. An orthogonal experiment was designed taking magnesium hydroxide, ammonium polyphosphate, and melamine as factors. The oil absorption and activation index were tested to determine the effect of titanate on the flame retardant additive. The pavement performance test was conducted to evaluate the effect of the flame retardant additive. Oxygen index test was conducted to confirm the effect of flame retardant on flame ability of asphalt binder. The results of this study showed that the new composite flame retardant is more effective in improving the compatibility between flame retardant and asphalt and reducing the limiting oxygen index of asphalt binder tested in this study.

  4. Fireproofing and heat insulating performance improvement of EG/ATH modified intumescent flame retardant coating treated under Co-60 radiation

    Science.gov (United States)

    Zhang, Yuehong; Luan, Weiling; Jiang, Tao

    2017-12-01

    New intumescent flame retardant (IFR) coatings with different fire retardants were prepared in this paper. Expandable graphite (EG) and Aluminium hydroxide (ATH) were respectively added into the conventional IFR coating system, which included ammonium polyphosphate (APP) / pentaerythritol (PER) / melamine (MEL). The fireproofing time and heat insulating properties of the additives acted as fire retardants were investigated via thermogravimetry analysis (TGA) and fire resistance test of homemade big panel test. The morphology of the char layer structure was achieved by scanning electron microscopy (SEM). The highlight of the paper was that the coating samples were pretreated under Co-60 radiation. The influence of radiation on the fire resistance time and char layer height was investigated. The results showed that the prepared IFR coatings can be used in Co-60 radiation for more than 90 min when encountering fire. It would be a reference for radiation shielding in nuclear environment.

  5. The Effect of Particle Size of Wollastonite Filler on Thermal Performance of Intumescent Fire Retardant Coating

    Directory of Open Access Journals (Sweden)

    Zia-ul-Mustafa M.

    2014-07-01

    Full Text Available Intumescent Fire retardant coatings (IFRC’s are one of the simplest ways to protect substrates exposed to fire. In this study, Wollastonite (W filler of two different particle sizes were used to determine the fire performance of intumescent fire retardant coating. The basic ingredients of the coating were ammonium poly-phosphate (APP as acid source, expandable graphite (EG as carbon source, melamine (MEL as blowing agent in epoxy binder, boric acid as additive and hardener as curing agent. A series of coating formulations were developed by using different weight percentages of both sized Wollastonite fillers. The coated steel substrate samples were tested for fire performance using Bunsen burner and char expansion was measured using furnace fire test. A Comparison of the coatings thermal performance was determined. Wollastonite containing filler particle size 10 μm showed better thermal performance than formulations containing filler’s particle size 44 μm.

  6. Application of mammalian cytogenetics to mutagenicity studies

    International Nuclear Information System (INIS)

    Brewen, J.G.

    1977-01-01

    Studies on induction of chromosome damage in germ cells by triethylene melamine (TEM) included determination of frequencies of chromosomal aberrations observed in human leukocytes after treating different stages of the cell cycle with TEM, frequencies of chromatid aberrations in metaphase I oocytes and the female pronuclear chromosomes following treatment of female mice with TEM, and frequencies of labeled diplotene-diakinesis figures and chromosome abberations at various intervals after treatment of primary spermatocytes with TEM and 3 H-thymidine. Studies on effects of low linear energy transfer radiation on mouse oocytes showed that the frequency of aberrations increased as a function of time and remained constant 8 to 9 days post-exposure. It was concluded that cytogenetic procedures were adequate to evaluate certain mutagenic end points

  7. RPC operation at high temperature

    CERN Document Server

    Aielli, G; Cardarelli, R; Di Ciaccio, A; Di Stante, L; Liberti, B; Paoloni, A; Pastori, E; Santonico, R

    2003-01-01

    The resistive electrodes of RPCs utilised in several current experiments (ATLAS, CMS, ALICE, BABAR and ARGO) are made of phenolic /melaminic polymers, with room temperature resistivities ranging from 10**1**0 Omega cm, for high rate operation in avalanche mode, to 5 multiplied by 10**1**1 Omega cm, for streamer mode operation at low rate. The resistivity has however a strong temperature dependence, decreasing exponentially with increasing temperature. We have tested several RPCs with different electrode resistivities in avalanche as well as in streamer mode operation. The behaviours of the operating current and of the counting rate have been studied at different temperatures. Long-term operation has also been studied at T = 45 degree C and 35 degree C, respectively, for high and low resistivity electrodes RPCs.

  8. Bis(1,10-phenanthroline-κ2N,N′(sulfato-κ2O,O′cobalt(II propane-1,3-diol solvate

    Directory of Open Access Journals (Sweden)

    Kai-Long Zhong

    2010-03-01

    Full Text Available The title compound, [Co(SO4(C12H8N22]·C3H8O2, was obtained unexpectedly as a by-product during an attempt to synthesize a mixed-ligand complex of CoII with 1,10-phenanthroline (phen and melamine via a solvothermal reaction. The CoII metal ions are in a distorted octahedral coordination environment formed by four N atoms from two chelating phen ligands and two O atoms from a bidentate sulfate ligand. The two chelating N2C2 groups are almost perpendicular to each other [dihedral angle = 80.06 (8°]. A twofold rotation axis passes through the Co and S atoms, and also through the central C atom of the propane-1,3-diol solvent molecule. Intermolecular O—H...O hydrogen bonds help to stabilize the structure.

  9. Flexible, lightweight and paper-like supercapacitors assembled from nitrogen-doped multi-dimensional carbon materials

    DEFF Research Database (Denmark)

    Cao, Xianyi; Duus, Jens Øllgaard; Chi, Qijin

    2017-01-01

    ) with melamine as the nitrogen doping source. The N3CP electrode has demonstrated several advantages, such as enhanced porosity, improved electrical conductivity and high nitrogen doping level. Electrochemical tests have shown that thanks to the synergistic effects of hybrid-dimensional optimized carbon...... hydrophilicity. In this work, a facile approach is developed to prepare nitrogen-doped carbon based flexible and free-standing paper electrodes {N3CPs) built from three types of representative carbon materials in different dimensions {OD: carbon black nanoparticles (CBNPs); 10: carbon nanotubes {CNTs); 20: GRSs......-dimensional/one-dimensional {00/10) nanomaterials have been tested as spacers to prevent GR sheets {GRSs) from restacking for constructing three-dimensional {30) porous electrodes. Besides, heteroatom doping of GRSs could further improve their specific capacitance by introducing pseudocapacitive characteristics and increasing...

  10. Resin composite for sealing and its use in a solar cell. Fushiyo jushi soseibutsu oyobi sore wo mochiita taiyo denchi

    Energy Technology Data Exchange (ETDEWEB)

    Toma, H.; Mimura, T.; Takehara, N.

    1994-01-28

    This invention presents resin composites for sealing of a solar cell composed of a hardening resin and a thermoplastic resin which has a number average molecular weight larger than that of the hardening resin and is soluble in the hardening resin, and the invention affords a solar cell to endure a long-term stable operation and to give a good performance. The hardening resin includes unsaturated polyester resin, phenolic resin, alkyd resin, unsaturated acrylic resin, epoxy resin, polyurethane resin, melamine resin, diallyl phthalate resin, their oligomers and their modifications. The thermoplastic resin includes saturated polyester resin, phenolic resin, acrylic resin, styrene resin, epoxy resin, polyurethane resin, polyvinyl acetate resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyacetal resin, their modifications and their copolymer resin. 2 figs., 3 tabs.

  11. A mechanistic study explaining the synergistic viscosity increase obtained from polyethylene oxide (PEO) and {beta}-naphthalene sulfonate (BNS) in shotcrete

    Energy Technology Data Exchange (ETDEWEB)

    Pickelmann, J.; Plank, J., E-mail: sekretariat@bauchemie.ch.tum.de

    2012-11-15

    In shotcrete, a combination of polyethylene oxide (PEO) and {beta}-naphthalene sulfonate (BNS) is commonly applied to reduce rebound. Here, the mechanism for the synergistic viscosity increase resulting from this admixture combination was investigated via x-ray diffraction (XRD), infrared and nuclear magnetic resonance (NMR) spectroscopy. It was found that the electron-rich aromatic rings present in BNS donate electrons to the alkyl protons of PEO and thus increase the electron density there. This rare interaction is known as CH-{pi} interaction and leads to the formation of a supramolecular structure whereby PEO chains bind weakly to BNS molecules. Through this mechanism a polymer network exhibiting exceptionally high molecular weight and thus viscosity is formed. Among polycondensates, sulfanilic acid-phenol-formaldehyde (SPF) provides even higher synergy with PEO than BNS while melamine (PMS), acetone (AFS) or polycarboxylate (PCE) based superplasticizers do not work at all. Effectiveness of lignosulfonates is dependent on their degree of sulfonation.

  12. Development of new addition-type composite resins

    Science.gov (United States)

    Kray, R. J.

    1981-01-01

    The most promising of a number of new addition type polyimides and polyaromatic melamine (NCNS) resins for use in high performance composite materials. Three different cure temperature ranges were of interest: 530-560 K (500-550 F), 475-530 K (400-500 F), and 450 K (350 F). Examined were a wide variety of polyimide precursors terminated with 5 norbornene groups and addition polymerized at 560 K similar to PMR-15 and LARC-160 polyimides. In addition, a number of lower curing cinnamal end capped polyimides and a bismaleimide were investigated but were not found promising. A group of NCNS resins were investigated and some were found to be superior to current epoxy resins in moisture resistance, oxidative aging and flame and smoke properties.

  13. Solvent-induced synthesis of nitrogen-doped hollow carbon spheres with tunable surface morphology for supercapacitors

    Science.gov (United States)

    Liu, Feng; Yuan, Ren-Lu; Zhang, Ning; Ke, Chang-Ce; Ma, Shao-Xia; Zhang, Ru-Liang; Liu, Lei

    2018-04-01

    Nitrogen doped hollow carbon spheres (NHCSs) with tunable surface morphology have been prepared through one-pot carbonization method by using melamine-formaldehyde spheres as template and resorcinol-based resin as carbon precursor in ethanol-water solution. Well-dispersed NHCSs with particle size of 800 nm were obtained and the surface of NHCSs turn from smooth to tough, wrinkled, and finally concave by increasing the ethanol concentration. The fabricated NHCSs possessed high nitrogen content (3.99-4.83%) and hierarchical micro-dual mesoporous structure with surface area range of 265-405 m2 g-1 and total pore volume of 0.18-0.29 cm3 g-1, which contributed to high specific capacitance, excellent rate capability and long cycle life.

  14. Nitrogen-promoted self-assembly of N-doped carbon nanotubes and their intrinsic catalysis for oxygen reduction in fuel cells.

    Science.gov (United States)

    Wang, Zhijian; Jia, Rongrong; Zheng, Jianfeng; Zhao, Jianghong; Li, Li; Song, Jinling; Zhu, Zhenping

    2011-03-22

    Nitrogen atoms were found to exhibit a strong ability to promote the self-assembly of nitrogen-doped carbon nanotubes (NCNTs) from gaseous carbons, without an assistance of metal atoms. On the basis of this discovery, pure metal-free CNTs with a nitrogen-doping level as high as 20 atom % can be directly synthesized using melamine as a C/N precursor. This offers a novel pathway for carbon nanotube synthesis. Furthermore, the metal-free and intact characteristics of the NCNT samples facilitate a clear verification of the intrinsic catalytic ability of NCNTs. The results show that the NCNTs intrinsically display excellent catalytic activity for oxygen reduction in fuel cells, comparable to traditional platinum-based catalysts. More notably, they exhibit outstanding stability, selectivity, and resistance to CO poisoning, much superior to the platinum-based catalysts.

  15. Utilization of Bamboo as Lightweight Sandwich Panels

    Directory of Open Access Journals (Sweden)

    Suthon SRIVARO

    2016-05-01

    Full Text Available Lightweight sandwich panels consisting of bamboo faces and oil palm trunk core were manufactured using melamine urea formaldehyde with the resin content of 250 g/m2 (solid basis. The parameters examined were node and density of bamboo faces. Physical (board density, thickness swelling and water absorption and mechanical (modulus of elasticity and modulus of rupture properties of the sandwich board obtained were investigated and compared with other bamboo products and commercial wood based products. Result showed that this panel had better dimensional stability than those of other bamboo products but lower bending strength. Node of bamboo had no significant effect on any board properties examined. Most of board properties were influenced by bamboo face density. Comparing the properties to commercial wood based products, this panel could be used as wall/floor applications.

  16. PERFORMANCE OF MUF RESINS FOR PARTICLEBOARDS BEFORE AND AFTER SPRAY-DRYING

    Directory of Open Access Journals (Sweden)

    Antonio PIZZI

    2012-12-01

    Full Text Available Melamine-urea-formaldehyde (MUF resins can be spray dried to obtain resins in powder form and indefinite shelf-life. Application as particleboard adhesives of such resins after redissolving them in water does yield resins of excellent performance as particleboard adhesives if the natural advancement caused by the heat in the spray-drier chamber is taken into account. CP MAS 13C NMR analysis of the spray-dried resin in powder form and thermomechanical analysis has shown some difference in behaviour in relation to MUF resins of the same level of water tolerance which have not been spray-dried. These small but significant differences can be ascribed to differences in resin structure.

  17. Eco-friendly Crosslinking Agent for Acid Functional Acrylic Resin

    Directory of Open Access Journals (Sweden)

    Archana Shah

    2009-01-01

    Full Text Available Oil from J. multifida was extracted and it was first converted into N,N-bis(2-hydroxyethyl Jatropha fatty amide (HEJFA. HEJFA has been synthesized by reaction between Jatropha oil and diethanol amine in presence of zinc oxide as a catalyst. The reaction is relatively rapid and proceeded to high yield at 200±5 OC. The resulting HEJFA was used to formulate thermosetting coating compositions. Films were cured at ambient (air drying and elevated (stove drying temperatures using N, N-bis(2-hydroxyethyl Jatropha fatty amide (HEJFA as eco-friendly crosslinking agent for acrylic resin. The coating performance of the various compositions was tested by measurement of scratch hardness, impact strength and chemical resistance. The results show better performance of the HEJFA based compositions compared to butylated melamine formaldehyde (MF based compositions.

  18. Formation and Controlled Drug Release Using a Three-Component Supramolecular Hydrogel for Anti-Schistosoma Japonicum Cercariae

    Directory of Open Access Journals (Sweden)

    Yibao Li

    2016-03-01

    Full Text Available A novel three-component supramolecular hydrogel based on riboflavin, melamine and amino acid derivatives were constructed for controlled release of pesticides, Niclosamide derivatives. The formation of hydrogel may be attributed to self-assemble via hydrogen bonding and π–π interaction, which have been researched via scanning electron microscopy (SEM and Fourier transform infrared (FT-IR spectra. The rheological experiments showed that the hydrogel materials and drug-loaded hydrogel all demonstrated good mechanical strength and high stability. Further experimental results indicated that the drug-loaded hydrogels show large drug loadings, long-term release time and relatively higher efficiency to anti-cercariae in the water environment.

  19. Melamine–Glyoxal–Glutaraldehyde Wood Panel Adhesives without Formaldehyde

    Directory of Open Access Journals (Sweden)

    Xuedong Xi

    2017-12-01

    Full Text Available (MGG’ resin adhesives for bonding wood panels were prepared by a single step procedure, namely reacting melamine with glyoxal and simultaneously with a much smaller proportion of glutaraldehyde. No formaldehyde was used. The inherent slow hardening of this resin was overcome by the addition of N-methyl-2-pyrrolidone hydrogen sulphate ionic liquid as the adhesive hardener in the glue mix. The plywood strength results obtained were comparable with those obtained with melamine–formaldehyde resins pressed under the same conditions. Matrix assisted laser desorption ionisation time of flight (MALDI ToF and Fourier transform Infrared (FTIR analysis allowed the identification of the main oligomer species obtained and of the different types of linkages formed, as well as to indicate the multifaceted role of the ionic liquid. These resins are proposed as a suitable substitute for equivalent formaldehyde-based resins.

  20. N-Doped Carbon Xerogels as Pt Support for the Electro-Reduction of Oxygen

    Directory of Open Access Journals (Sweden)

    Cinthia Alegre

    2017-09-01

    Full Text Available Durability and limited catalytic activity are key impediments to the commercialization of polymer electrolyte fuel cells. Carbon materials employed as catalyst support can be doped with different heteroatoms, like nitrogen, to improve both catalytic activity and durability. Carbon xerogels are nanoporous carbons that can be easily synthesized in order to obtain N-doped materials. In the present work, we introduced melamine as a carbon xerogel precursor together with resorcinol for an effective in-situ N doping (3–4 wt % N. Pt nanoparticles were supported on nitrogen-doped carbon xerogels and their activity for the oxygen reduction reaction (ORR was evaluated in acid media along with their stability. Results provide new evidences of the type of N groups aiding the activity of Pt for the ORR and of a remarkable stability for N-doped carbon-supported Pt catalysts, providing appropriate physico-chemical features.

  1. Melaminium 2,4,6-trihydroxybenzoate dihydrate

    Directory of Open Access Journals (Sweden)

    Timothy J Prior

    2009-09-01

    Full Text Available In the title compound, C3H7N6+·C7H5O5−·2H2O, the melaminium and benzoate ions are approximately planar (r.m.s. deviation of the non-hydrogen atoms is 0.093 Å and there is a strong C22(8 hydrogen-bonding embrace between them. The centre of symmetry generates a second acid–base pair which is bound to the first by a C22(8 (N—H...N embrace common between melamine molecules in similar compounds. Further extensive hydrogen bonding assembles the components into a three-dimensional hydrogen-bonded network.

  2. In situ nanoparticle diagnostics by multi-wavelength Rayleigh-Mie scattering ellipsometry

    CERN Document Server

    Gebauer, G

    2003-01-01

    We present and discuss the method of multiple-wavelength Rayleigh-Mie scattering ellipsometry for the in situ analysis of nanoparticles. It is applied to the problem of nanoparticles suspended in low-pressure plasmas. We discuss experimental results demonstrating that the size distribution and the complex refractive index can be determined with high accuracy and present a study on the in situ analysis of etching of melamine-formaldehyde nanoparticles suspended in an oxygen plasma. It is also shown that particles with a shell structure (core plus mantle) can be analysed by Rayleigh-Mie scattering ellipsometry. Rayleigh-Mie scattering ellipsometry is also applicable to in situ analysis of nanoparticles under high gas pressures and in liquids.

  3. High-pressure pyrolysis study of C sub 3 N sub 6 H sub 6 : a route to preparing bulk C sub 3 N sub 4

    CERN Document Server

    Ma, H A; Chen, L X; Zhu, P W; Guo, W L; Guo, X B; Wang, Y D; Li, S Q; Zou Guang Tian; Zhang, G; Bex, P

    2002-01-01

    In order to prepare bulk C sub 3 N sub 4 , high-pressure pyrolysis of melamine (C sub 3 N sub 6 H sub 6) at different temperatures was carried out. The products were characterized by C, N, H element analysis, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffractometry. The results of the analysis reveal that graphitic phase C sub 3 N sub 4 has been synthesized. It provides a novel route to synthesis of the theoretical superhard cubic C sub 3 N sub 4 and other C sub 3 N sub 4 phases from organic compounds by a high-pressure and high-temperature method.

  4. Laser ablation of molecular carbon nitride compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, D., E-mail: d.fischer@fkf.mpg.de [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Schwinghammer, K. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany); Sondermann, C. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Lau, V.W.; Mannhart, J. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Lotsch, B.V. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany)

    2015-09-15

    We present a method for the preparation of thin films on sapphire substrates of the carbon nitride precursors dicyandiamide (C{sub 2}N{sub 4}H{sub 4}), melamine (C{sub 3}N{sub 6}H{sub 6}), and melem (C{sub 6}N{sub 10}H{sub 6}), using the femtosecond-pulsed laser deposition technique (femto-PLD) at different temperatures. The depositions were carried out under high vacuum with a femtosecond-pulsed laser. The focused laser beam is scanned on the surface of a rotating target consisting of the pelletized compounds. The resulting polycrystalline, opaque films were characterized by X-ray powder diffraction, infrared, Raman, and X-ray photoelectron spectroscopy, photoluminescence, SEM, and MALDI-TOF mass spectrometry measurements. The crystal structures and optical/spectroscopic results of the obtained rough films largely match those of the bulk materials.

  5. Effect of household and industrial processing on the levels of pesticide residues and degradation products in melons.

    Science.gov (United States)

    Bonnechère, A; Hanot, V; Bragard, C; Bedoret, T; van Loco, J

    2012-01-01

    Two varieties of melons (Cucumis melo) were treated with two fungicides (carbendazim and maneb) and four insecticides (acetamiprid, cyromazin, imazalil and thiamethoxam) to quantify the effect of household processing on the pesticide residues. To ensure sufficiently high levels of residues in flesh and peel, the most concentrated formulations were applied observing good agricultural practice. The peeling step decreased the concentration of pesticide residues for maneb, imazalil and acetamiprid by more than 90%. Cyromazin, carbendazim and thiamethoxam were reduced by approximately 50%. The reduction of the pesticides could not be fully explained by the systemic character of the pesticides. However, the agricultural practices (time of application), solubility and mode of action (systemic versus contact pesticide) of the pesticides could be used to explain the difference in processing factors for the studied pesticides. Degradation products (melamine and ethylenethiourea) were also investigated in this study, but were not detected.

  6. Process for the reduction of nitrogen oxides in an effluent

    Energy Technology Data Exchange (ETDEWEB)

    Epperly, W.R.; Sullivan, J.C.

    1988-09-13

    A process is described for reducing the concentration of nitrogen oxides in an effluent from the combustion of a carbonaceous fuel, which process comprises injecting into the effluent ammonia and an enhancer selected from the group consisting of hexamethylenetetramine, a lower carbon alcohol, a hydroxyl amino hydrocarbon, sugar, furfural, furfural derivatives, an amino acid, a protein-containing composition, mixtures of ortho-, meta-, and para-methyl phenols, guanidine, guanidine carbonate, biguanidine, guanylurea sulfate, melamine, dicyandiamide, calcium cyanamide, biuret, 1,1'-azobisformamide, methylol urea, methylol urea-urea condensation product, dimethylol urea, methyl urea, dimethyl urea, and mixtures thereof, at an effluent temperature above about 1300/sup 0/F and a molar ratio of nitrogen in the ammonia and enhancer to the baseline nitrogen oxides level of about 1:5 to about 6:1 wherein the excess of oxygen in the effluent is no greater than about 6%.

  7. Origin of organic matter in early solar system. VI - Catalytic synthesis of nitriles, nitrogen bases and porphyrin-like pigments.

    Science.gov (United States)

    Hayatsu, R.; Matsuoka, S.; Anders, E.; Studier, M. H.

    1972-01-01

    A variety of nitrogen compounds have been synthesized by a static Fischer-Tropsch type reaction from CO, D2 and ND3, with Ni-Fe and Al2O3 catalysts. In this reaction, the gas is heated to 500-700 C for about 0.5 hr, and then cycled through lower temperatures (100-400 C) for 1-14 days. Products were analyzed by mass spectrometry in conjunction with gas chromatography and other chromatographic techniques. Compounds produced include alkyl cyanides, pyrroles, porphyrin-like compounds, guanidines, hydantoin, uracil and its derivatives, thymine, adenine, guanine, xanthine, melamine, as well as alkanes, alkenes and aromatic hydrocarbons. Such reactions may have been involved in the production of interstellar molecules, organic compounds in meteorites, and prebiotic organic matter on planets.

  8. Nitrogen-doped carbon spheres: A new high-energy-density and long-life pseudo-capacitive electrode material for electrochemical flow capacitor.

    Science.gov (United States)

    Hou, Shujin; Wang, Miao; Xu, Xingtao; Li, Yandong; Li, Yanjiang; Lu, Ting; Pan, Likun

    2017-04-01

    One of the most challenging issues in developing electrochemical flow capacitor (EFC) technology is the design and synthesis of active electrode materials with high energy density and long cycle life. However, in practical cases, the energy density and cycle ability obtained currently cannot meet the practical need. In this work, we propose a new active material, nitrogen-doped carbon spheres (NCSs), as flowable electrodes for EFC application. The NCSs were prepared via one-pot hydrothermal synthesis in the presence of resorcinol/formaldehyde as carbon precursors and melamine as nitrogen precursor, followed by carbonization in nitrogen flow at various temperatures. The results of EFC experiments demonstrate that NCSs obtained at 800°C exhibit a high energy density of 13.5Whkg -1 and an excellent cycle ability, indicating the superiority of NCSs for EFC application. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Compressibility and phase contrast imaging of a irradiated polyurethane foam blocks

    International Nuclear Information System (INIS)

    Naik, Y.; Kulkarni, S.G.; Manjunath, B.S.; Patel, R.J.; Agarwal, A.K.; Kashyap, Y.; Sinha, A.

    2013-01-01

    Polyurethane foam was prepared with a view to use them as a protective enclosure for radioactive material transport package against accidental mechanical shock and fire. The foam samples were prepared by mixing the polyol premixed with additives such as water as blowing agent, melamine polyphosphate as a flame retardants (FR) and catalyst with isocynate keeping NCO/OH ratio as 1.1. It was observed that the irradiation of the foam results in cross linking leading to increased wall thickness and shrinkage of cellular structure. This leads to increased strain around the foam bubble. Increased exposure to gamma rays to higher doses results in reptures at the cellular boundary connecting the bubble structure, leading to decreased mechanical strength. This leads again to increase in deformation seen in the 15 and 20 kGy irradiated samples

  10. Validation of the direct analysis in real time source for use in forensic drug screening.

    Science.gov (United States)

    Steiner, Robert R; Larson, Robyn L

    2009-05-01

    The Direct Analysis in Real Time (DART) ion source is a relatively new mass spectrometry technique that is seeing widespread use in chemical analyses world-wide. DART studies include such diverse topics as analysis of flavors and fragrances, melamine in contaminated dog food, differentiation of writing inks, characterization of solid counterfeit drugs, and as a detector for planar chromatography. Validation of this new technique for the rapid screening of forensic evidence for drugs of abuse, utilizing the DART source coupled to an accurate mass time-of-flight mass spectrometer, was conducted. The study consisted of the determination of the lower limit of detection for the method, determination of selectivity and a comparison of this technique to established analytical protocols. Examples of DART spectra are included. The results of this study have allowed the Virginia Department of Forensic Science to incorporate this new technique into their analysis scheme for the screening of solid dosage forms of drugs of abuse.

  11. 350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

    Science.gov (United States)

    Naqvi, A. A.; Al-Matouq, Faris A.; Khiari, F. Z.; Gondal, M. A.; Rehman, Khateeb-ur; Isab, A. A.; Raashid, M.; Dastageer, M. A.

    2013-11-01

    Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53-3.68, 4.51, 5.27-5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

  12. [The impact of melafen on the expression of chloroplastic chaperone protein HSP70B and photosynthetic pigments in cells of Chlamydomonas reinhardtii].

    Science.gov (United States)

    Ermokhina, O V; Belkina, G G; Oleskina, Iu P; Fattakhov, S G; Iurina, N P

    2009-01-01

    The effects of growth regulator of the new generation-melamine salt of bis(oxymethyl)phosphine acid (melafen)--on culture growth, pigment and protein content, and the induction of protective chloroplastic chaperone HSP70B in Chlamydomonas reinhardtii CW15 cells were studied. Melafen exhibited 10-30% growth inhibition at 10(-9)-10(-2)% concentration. At 10(-9)-10(-4)% of melafen electrophoretic concentration, the pattern of cellular proteins was similar to the control. The alterations in protein content of algae cells were detected only at 10(-2)% concentration. The content of chlorophyll and carotenoids in melafen-treated cells was 17-40% lower than in the control. Melafen at 10(-9)-109-2)% concentration inhibited HSP70B induction by 39-43% compared to untreated cells. The potential mechanism of melafen effect might involve its influence on nuclear gene expression.

  13. Nitrogen Detection in Bulk Samples Using a D-D Reaction-Based Portable Neutron Generator

    Directory of Open Access Journals (Sweden)

    A. A. Naqvi

    2013-01-01

    Full Text Available Nitrogen concentration was measured via 2.52 MeV nitrogen gamma ray from melamine, caffeine, urea, and disperse orange bulk samples using a newly designed D-D portable neutron generator-based prompt gamma ray setup. Inspite of low flux of thermal neutrons produced by D-D reaction-based portable neutron generator and interference of 2.52 MeV gamma rays from nitrogen in bulk samples with 2.50 MeV gamma ray from bismuth in BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays indicates satisfactory performance of the setup for detection of nitrogen in bulk samples.

  14. Effect of pH on the adsorption and photocatalytic degradation of sulfadimidine in Vis/g-C3N4progress.

    Science.gov (United States)

    Yang, Bin; Mao, Xuhui; Pi, Liu; Wu, Yixiao; Ding, Huijun; Zhang, Weihao

    2017-03-01

    In this study, g-C 3 N 4 was synthesized by thermal polycondensation of melamine and was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy, and scanning electron microscopy. Results showed that g-C 3 N 4 degraded sulfadimidine (SMD) under visible light, in which the adsorption and photocatalytic degradation was influenced by pH. The maximum adsorption capacity was achieved at approximately pH 5. The highest degradation rate constant was obtained at strong acid and alkali. In addition, the degradation mechanism of g-C 3 N 4 was evaluated with the help of quencher agents. The intermediates, degradation pathways, and mineralization of SMD were also determined to evaluate the degradation and oxidation ability of g-C 3 N 4 .

  15. Trace-level phosphorus and sodium co-doping of g-C3N4 for enhanced photocatalytic H2 production

    Science.gov (United States)

    Cao, Shaowen; Huang, Qian; Zhu, Bicheng; Yu, Jiaguo

    2017-05-01

    The conversion of solar energy into hydrogen fuels by semiconductor photocatalysts has been paid great attention in recent years. g-C3N4 has emerged as a rising star in this area for its numerous advantages. In this work, trace-amount phosphorus and sodium co-doped g-C3N4 is prepared by polymerizing the mixed precursors of melamine and sodium tripolyphosphate. The resultant photocatalyst exhibits remarkably enhanced photocatalytic performance in H2 production. Experimental analysis and theoretical calculation indicate that such performance enhancement is mainly due to the improved charge transfer and separation resulting from the interstitial doping of sodium and phosphorus, as well as the more porous structure with enlarged specific surface area.

  16. Structural insights into photocatalytic performance of carbon nitrides for degradation of organic pollutants

    Science.gov (United States)

    Oh, Junghoon; Shim, Yeonjun; Lee, Soomin; Park, Sunghee; Jang, Dawoon; Shin, Yunseok; Ohn, Saerom; Kim, Jeongho; Park, Sungjin

    2018-02-01

    Degradation of organic pollutants has a large environmental impact, with graphitic carbon nitride (g-C3N4) being a promising metal-free, low cost, and environment-friendly photocatalyst well suited for this purpose. Herein, we investigate the photocatalytic performance of g-C3N4-based materials and correlate it with their structural properties, using three different precursors (dicyandiamide, melamine, and urea) and two heating processes (direct heating at 550 °C and sequential heating at 300 and 550 °C) to produce the above photocatalysts. We further demonstrate that sequential heating produces photocatalysts with grain sizes and activities larger than those of the catalysts produced by direct heating and that the use of urea as a precursor affords photocatalysts with larger surface areas, allowing efficient rhodamine B degradation under visible light.

  17. Nickel Oxide and Nickel Co-doped Graphitic Carbon Nitride Nanocomposites and its Octylphenol Sensing Application

    KAUST Repository

    Gong, Wanyun

    2015-11-16

    Nickel oxide and nickel co-doped graphitic carbon nitride (NiO-Ni-GCN) nanocomposites were successfully prepared by thermal treatment of melamine and NiCl2 6H2O. NiO-Ni-GCN nanocomposites showed superior electrochemical catalytic activity for the oxidation of octylphenol to pure GCN. A detection method of octylphenol in environmental water samples was developed based at NiO-Ni-GCN nanocomposites modified electrode under infrared light irradiation. Differential pulse voltammetry was used as the analytic technique of octylphenol, exhibiting stable and specific concentration-dependent oxidation signal in the presence of octylphenol in the range of 10nM to 1μM and 1μM to 50μM, with a detection limit of 3.3nM (3S/N). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Preparation of nanodispersed titania using stabilized ammonium nitrate melts

    KAUST Repository

    Raciulete, Monica

    2010-10-01

    An expedite one-step approach using simple precursors has been proposed to obtain metallic oxide compounds and exemplified by preparation of highly dispersed TiO2. The technique consists in heating to 400500 °C of molten ammonium nitrate stabilized with an organic nitrogen-containing compound (urea, melamine, ammonium oxalate) and containing dissolved metal salt precursor (TiOCl2). The crystallites of the resulting TiO2 demonstrated variable size and shape as a function of stabilizer used. Their activity in photocatalytic oxidation of formic acid also depends on the nature of the stabilizer. The catalysts as-prepared showed high photocatalytic performance, superior to that of the Degussa P25 reference. Nitrogen containing stabilizers play a double role of increasing the process safety and modifying the properties of the solid products. © 2010 Elsevier Inc. All rights reserved.

  19. Recent advances in chemical imaging technology for the detection of contaminants for food safety and security

    Science.gov (United States)

    Priore, Ryan J.; Olkhovyk, Oksana; Drauch, Amy; Treado, Patrick; Kim, Moon; Chao, Kaunglin

    2009-05-01

    The need for routine, non-destructive chemical screening of agricultural products is increasing due to the health hazards to animals and humans associated with intentional and unintentional contamination of foods. Melamine, an industrial additive used to increase flame retardation in the resin industry, has recently been used to increase the apparent protein content of animal feed, of infant formula, as well as powdered and liquid milk in the dairy industry. Such contaminants, even at regulated levels, pose serious health risks. Chemical imaging technology provides the ability to evaluate large volumes of agricultural products before reaching the consumer. In this presentation, recent advances in chemical imaging technology that exploit Raman, fluorescence and near-infrared (NIR) are presented for the detection of contaminants in agricultural products.

  20. Novel silicon nanoparticles with nitrogen-doped carbon shell dispersed in nitrogen-doped graphene and CNTs hybrid electrode for lithium ion battery

    Science.gov (United States)

    Tang, Xiaofu; Wen, Guangwu; Zhang, Yong; Wang, Dong; Song, Yan

    2017-12-01

    A Si-rGO/NCT composite, in which Si nanoparticles (SiNPs) are enwrapped with N-doped carbon and combine with N-doped graphene and CNTs as conductive matrices synthesized by simple solution-mixing and carbonization process with pyrolyzing melamine formaldehyde resin (MFR) is developed as a promising candidate anode material for lithium ion batteries (LIBs). The N-doped carbon outside SiNPs can not only improve the electrical conductivity of the composite, but also buffer the stress causing by huge volume change of SiNPs during the lithiation/delithiation process. The Si-rGO/NCT composite exhibits high specific capacity and good cycling stability (892.3 mAh g-1 at 100 mA g-1 up to 100 cycles), as well as improved rate capability. This approach provides a very facile route to obtain silicon-based anode materials.

  1. Harvesting solar light with crystalline carbon nitrides for efficient photocatalytic hydrogen evolution

    KAUST Repository

    Bhunia, Manas Kumar

    2014-08-14

    Described herein is the photocatalytic hydrogen evolution using crystalline carbon nitrides (CNs) obtained by supramolecular aggregation followed by ionic melt polycondensation (IMP) using melamine and 2,4,6-triaminopyrimidine as a dopant. The solid state NMR spectrum of 15N-enriched CN confirms the triazine as a building unit. Controlling the amount and arrangements of dopants in the CN structure can dramatically enhance the photocatalytic performance for H2 evolution. The polytriazine imide (PTI) exhibits the apparent quantum efficiency (AQE) of 15% at 400 nm. This method successfully enables a substantial amount of visible light to be harvested for H2 evolution, and provides a promising route for the rational design of a variety of highly active crystalline CN photocatalysts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Solidifying agent for radioactive waste

    International Nuclear Information System (INIS)

    Sakai, Etsuro; Kida, Tsutomu; Sasagawa, Yukio.

    1988-01-01

    Purpose: To apply solidifying treatment to boron-containing radioactive wastes while improving the durability, rapid hardening property and processing performance, as well as reducing the leaching property. Constitution: A solidifying agent comprising calcium aluminate having CaO and Al 2 O 3 at 1.5 - 4 molar ratio, super fine powder and high performance moderator is used. As the super fine powder, those having a grain size smaller by 1 - 2 orders than that of the calcium aluminate are preferred. Specifically, there can be used silica dust, calcium carbonate, silica gel, titanium oxide, aluminum oxide, etc. As the moderator, there are used those surface active agents of great dispersing performance not causing excess delay for coagulation or excess air entrainment when added in a great amount to cements. Specifically, there can be mentioned those mainly composed of salts of naphthalene sulfonic acid-formaldehyde condensates, salts of melamine sulfonic acid formaldehyde condensates, etc. (Ikeda, J.)

  3. Natural convection heat transfer enhancement using Microencapsulated Phase-Change-Material slurries

    International Nuclear Information System (INIS)

    Kubo, Shinji; Akino, Norio; Tanaka, Amane; Nakano, Fumihiko; Nagashima, Akira.

    1997-01-01

    The present study investigates natural convection heat transfer from a heated cylinder cooled by a water slurry of Microencapsulated Phase Change Material (MCPCM). A normal paraffin hydrocarbon with carbon number of 18 and melting point of 27.9degC, is microencapsulated by Melamine resin into particles of which average diameter is 9.5μm and specific weight is same as water. The slurry of the MCPCM and water is put into a test apparatus, which is a rectangular enclosure with a heated horizontal cylinder. As the concentrations of PCM in the slurry are changed in 1,3 and 5%, the heat transfer coefficients of the cylinder are larger than that of water as working fluid, by 3,20 and 35% enhancements respectively. (author)

  4. Natural convection heat transfer from a heated horizontal cylinder with Microencapsulated Phase-Change-Material slurries

    International Nuclear Information System (INIS)

    Kubo, Shinji; Akino, Norio; Tanaka, Amane; Nagashima, Akira

    1998-01-01

    The present study investigates natural convection heat transfer from a heated cylinder cooled by a water slurry of Microencapsulated Phase Change Material (MCPCM). A normal paraffin hydrocarbon with carbon number of 18 and melting point of 27.9degC, is microencapsulated by Melamine resin into particles of which average diameter is 9.5 μm and specific weight is same as water. The slurry of the MCPCM and water is put into a rectangular enclosure with a heated horizontal cylinder. The heat transfer coefficients of the cylinder were evaluated. Changing the concentrations of PCM and temperature difference between cylinder surface and working fluid. Addition of MCPCM into water, the heat transfer is enhanced significantly comparison with pure water in cases with phase change and is reduced slightly in cases without phase change. (author)

  5. Adhesion of perfume-filled microcapsules to model fabric surfaces.

    Science.gov (United States)

    He, Yanping; Bowen, James; Andrews, James W; Liu, Min; Smets, Johan; Zhang, Zhibing

    2014-01-01

    The retention and adhesion of melamine formaldehyde (MF) microcapsules on a model fabric surface in aqueous solution were investigated using a customised flow chamber technique and atomic force microscopy (AFM). A cellulose film was employed as a model fabric surface. Modification of the cellulose with chitosan was found to increase the retention and adhesion of microcapsules on the model fabric surface. The AFM force-displacement data reveal that bridging forces resulting from the extension of cellulose chains dominate the adhesion between the microcapsule and the unmodified cellulose film, whereas electrostatic attraction helps the microcapsules adhere to the chitosan-modified cellulose film. The correlation between results obtained using these two complementary techniques suggests that the flow chamber device can be potentially used for rapid screening of the effect of chemical modification on the adhesion of microparticles to surfaces, reducing the time required to achieve an optimal formulation.

  6. In-syringe extraction using dissolvable layered double hydroxide-polymer sponges templated from hierarchically porous coordination polymers.

    Science.gov (United States)

    Ghani, Milad; Frizzarin, Rejane M; Maya, Fernando; Cerdà, Víctor

    2016-07-01

    Herein we report the use of cobalt porous coordination polymers (PCP) as intermediates to prepare advanced extraction media based on layered double hydroxides (LDH) supported on melamine polymer foam. The obtained dissolvable Ni-Co LDH composite sponges can be molded and used as sorbent for the in-syringe solid-phase extraction (SPE) of phenolic acids from fruit juices. The proposed sorbent is obtained due to the surfactant-assisted self-assembly of Co(II)/imidazolate PCPs on commercially available melamine foam, followed by the in situ conversion of the PCP into the final dissolvable LDH coating. Advantageous features for SPE are obtained by using PCPs with hierarchical porosity (HPCPs). The LDH-sponge prepared using intermediate HPCPs (HLDH-sponge) is placed in the headspace of a glass syringe, enabling flow-through extraction followed by analyte elution by the dissolution of the LDH coating in acidic conditions. Three phenolic acids (gallic acid, p-hydroxybenzoic acid and caffeic acid) were extracted and quantified using high performance liquid chromatography. Using a 5mL sample volume, the obtained detection limits were 0.15-0.35μgL(-1). The proposed method for the preparation of HLDH-sponges showed a good reproducibility as observed from the intra- and inter-day RSD's, which were <10% for all analytes. The batch-to-batch reproducibility for three different batches of HLDH-sponges was 10.6-11.2%. Enrichment factors of 15-21 were obtained. The HLDH-sponges were applied satisfactorily to the determination of phenolic acids in natural and commercial fruit juices, obtaining relative recoveries among 89.7-95.3%. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. DETERMINACIÓN DEL ADHESIVO ÓPTIMO EN LA FABRICACIÓN DE VIGAS DE BAMBÚ (Guadua angustifolia PROCEDURE TO DETERMINE THE OPTIMUM ADHESIVE FOR MANUFACTURING TIMBER OF BAMBOO (Guadua angustifolia

    Directory of Open Access Journals (Sweden)

    HÉCTOR A GONZÁLEZ

    2009-06-01

    Full Text Available Esta publicación presenta diferentes procedimientos para la selección del mejor adhesivo entre varios pegantes, que permita una buena calidad en la unión de la línea de encolado en laminados de Guadua angustifolia Kunth, usada en la construcción de vigas estructurales. La metodología busca conocer la firmeza mecánica y la durabilidad de la unión encolada de tablillas de Bambú. Como primer criterio se investigó cual de ellos presentaba menor falla en la línea de encolado después de ser sometido al ensayo de desencolado (DIN EN 391 y como segundo criterio se investigó el mejor cumplimiento al esfuerzo de cizalladura (DIN EN 392 de la unión encolada. Los adhesivos con mejores resultados fueron el Melamin Harzleim y el Recorcin Harzleim.This publication presents different procedures for the selection of the best glue between several glue, it that allows a quality good in the union of the glue line in the laminated of Guadua angustifolia Kunth, it is used in the construction of structural beams. The methodology seeks to know the mechanical firmness and the durability of the union glued of boards of Bamboo. The first criterion investigated was which of the presented minor flaw in the glue line after was submitted to the essay of delaminating (DIN EN 391 and in second criterion was the best fulfillment of the strain shear (DIN EN 392 on the glue line. The adhesives with better results were the Melamin Harzleim and Recorcin Harzleim.

  8. Luminescent and magnetic properties of carbon-based FeYO{sub 3}/Y{sub 2}O{sub 3}:Eu{sup 3+} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Aibing, E-mail: aibing_1008@163.com [Department of Environmental and Chemical Engineering, Tangshan College, Tangshan 063000 (China); Key Laboratory of Micro-Nano Material Preparation and Application of Tangshan City, Tangshan College, Tangshan 063000 (China); Zhang, Zhiping [Department of Environmental and Chemical Engineering, Tangshan College, Tangshan 063000 (China)

    2015-11-30

    Highlights: • Carbon-based FeYO{sub 3}/Y{sub 2}O{sub 3}:Eu{sup 3+} nanocomposites (FeYO{sub 3}/Y{sub 2}O{sub 3}:Eu{sup 3+}/C) were prepared by the solid-state reaction method. • FeYO{sub 3} and Y{sub 2}O{sub 3}:Eu{sup 3+} nanoparticles are dispersed in carbon matrix. • FeYO{sub 3}/Y{sub 2}O{sub 3}:Eu{sup 3+}/C {sub 1:6:4} (M{sub S} = 1.80 emu g{sup −1}) has the best luminescent properties. • FeYO{sub 3}/Y{sub 2}O{sub 3}:Eu{sup 3+}/C {sub 1:3:4} has the highest M{sub S} 4.30 emu g{sup −1}. - Abstract: Bifunctional carbon-based FeYO{sub 3}/Y{sub 2}O{sub 3}:Eu{sup 3+} nanocomposites have been fabricated by a facile solid-state method using melamine as carbon source. The structure and morphology of the nanocomposites were characterized by X-ray diffraction and transmission electron microscopy. It is shown that FeYO{sub 3} and Y{sub 2}O{sub 3}:Eu{sup 3+} nanoparticles in the composites are dispersed in carbon matrix. A probable formation mechanism of the composites is proposed. The effects of dosages of Y{sub 2}O{sub 3}:Eu{sup 3+} and melamine on the luminescent and magnetic properties of composites are discussed.

  9. Adulteration detection in milk using infrared spectroscopy combined with two-dimensional correlation analysis

    Science.gov (United States)

    He, Bin; Liu, Rong; Yang, Renjie; Xu, Kexin

    2010-02-01

    Adulteration of milk and dairy products has brought serious threats to human health as well as enormous economic losses to the food industry. Considering the diversity of adulterants possibly mixed in milk, such as melamine, urea, tetracycline, sugar/salt and so forth, a rapid, widely available, high-throughput, cost-effective method is needed for detecting each of the components in milk at once. In this paper, a method using Fourier Transform Infrared spectroscopy (FTIR) combined with two-dimensional (2D) correlation spectroscopy is established for the discriminative analysis of adulteration in milk. Firstly, the characteristic peaks of the raw milk are found in the 4000-400 cm-1 region by its original spectra. Secondly, the adulterant samples are respectively detected with the same method to establish a spectral database for subsequent comparison. Then, 2D correlation spectra of the samples are obtained which have high time resolution and can provide information about concentration-dependent intensity changes not readily accessible from one-dimensional spectra. And the characteristic peaks in the synchronous 2D correlation spectra of the suspected samples are compared with those of raw milk. The differences among their synchronous spectra imply that the suspected milk sample must contain some kinds of adulterants. Melamine, urea, tetracycline and glucose adulterants in milk are identified respectively. This nondestructive method can be used for a correct discrimination on whether the milk and dairy products are adulterated with deleterious substances and it provides a new simple and cost-effective alternative to test the components of milk.

  10. One-step fabrication of novel superhydrophobic and superoleophilic sponge with outstanding absorbency and flame-retardancy for the selective removal of oily organic solvent from water

    Science.gov (United States)

    Xiang, Yuqian; Pang, Youyou; Jiang, Xiaomei; Huang, Jie; Xi, Fengna; Liu, Jiyang

    2018-01-01

    Absorbent materials integrated with superhydrophobicity, superoleophilicity and flame-retardancy are highly desired in the adsorption/removal of flammable oils/organic compounds as well as reducing the risk of fire and explosion. Here, one-step fabrication of novel superhydrophobic and superoleophilic sponge with outstanding absorbency and flame-retardancy was presented. Using raw melamine (ME) sponge as the supporting matrix, the formation of polydopamine (PDA) nanoaggregates via in-situ self-polymerization of high-concentrated dopamine and the covalent grafting of hydrophobic n-dodecylthiol (DT) onto PDA were combined in a feasible alkaline water/ethanol medium. As investigated by scanning electron microscopy (SEM) and X-ray energy-dispersive spectroscopy (EDS), the as-prepared ME/PDA/DT sponge possessed hierarchical structure with submicron PDA nanoaggregates containing DT motif (low surface energy) on 3D interconnected porous network. It exhibited superhydrophobic (water contact angle 157.7°) and superoleophilic (oily/organic solvent contact angle 0° properties. Owing to the highly porous structure, superhydrophobic property, chemical and mechanical stability, the ME/PDA/DT sponge exhibited outstanding absorbency properties of oily organic solvents including fast absorption kinetics, high absorption capacity, and easy reusability. Also, the ME/PDA/DT sponge could be used for one-line continuous organic solvent/water separation. More interestingly, the ME/PDA/DT sponge demonstrated improved flame-retardant property as compared to the intrinsic flame-retardant nature of the raw melamine sponge. Consequently, the risk of fire and explosion was expected to reduce when the fabricated sponge was used as an absorbent for flammable oils and organic compounds. The ease of the one-step superhydrophobic/superoleophilic modification and the promising feature of the obtained materials exhibit great potential for application in oils/organic solvents clean-up.

  11. Generation of polycyclic aromatic hydrocarbons (PAH during woodworking operations

    Directory of Open Access Journals (Sweden)

    Evin Danisman Bruschweiler

    2012-10-01

    Full Text Available Occupational exposures to wood dust have been associated with an elevated risk of sinonasal cancer (SNC. Wood dust is recognized as a human carcinogen but the specific cancer causative agent remains unknown. One possible explanation is a co-exposure to; wood dust and polycyclic aromatic hydrocarbons (PAHs. PAHs could be generated during incomplete combustion of wood due to heat created by use of power tools.To determine if PAHs are generated from wood during common woodworking operations, PAHs concentrations in wood dust samples collected in an experimental chamber operated under controlled conditions were analyzed. In addition, personal air samples from workers exposed to wood dust (n=30 were collected.Wood dust was generated using tree different power tools: vibrating sander, belt sander, and saw; and six wood materials: fir, Medium Density Fiberboard (MDF, beech, mahogany, oak and wood melamine. Monitoring of wood workers was carried out by means of personnel sampler device during wood working operations. We measured 21 PAHs concentrations in wood dust samples by capillary gas chromatographic-ion trap mass spectrometric analysis (GC-MS.Total PAH concentrations in wood dust varied greatly (0.24 – 7.95 ppm with the lowest being in MDF dust and the highest in wood melamine dust. Personal exposures to PAHs observed were between 37.5-119.8 ng m-3 among workers during wood working operations.Our results suggest that PAH exposures during woodworking operation are present and hence could play a role in the mechanism of cancer induction related to wood dust exposure.

  12. Significance of optimal N-doping in mesoporous carbon framework to achieve high specific capacitance

    Science.gov (United States)

    Sahoo, Malaya K.; Gogoi, Pranjal; Rajeshkhanna, G.; Chilukuri, Satyanarayana V.; Rao, G. Ranga

    2017-10-01

    Nitrogen-doped mesoporous carbon (NMC) has been synthesized by sol-gel process using a mixture of phenol and formaldehyde as source of carbon, and melamine as source of nitrogen. The Ludox-AS40 (40 wt% SiO2) is employed, for the first time, as hard template to obtain polymeric gel by prolonged heat treatment at 80 °C. The wt% of nitrogen is tuned by varying the weight ratio of melamine to phenol. Stable mesoporous carbon frameworks are obtained by pyrolysis of the dry gel at 800 °C in nitrogen atmosphere and treated with alkali to remove silica. One of the carbon framework samples has 11 wt% nitrogen doping and shows pore volume of 0.5 cm3 g-1 and surface area 609 m2 g-1. The other carbon frame work sample has 6 wt% nitrogen doping and shows higher pore volume of 1.1 cm3 g-1 and surface area 736 m2 g-1. The later sample exhibits highest electrochemical capacitance of 196 F g-1 at 0.5 A g-1 while the former shows only 146 F g-1 at 0.5 A g-1. However, both the NMC electrodes show good cyclic performance (91% of the initial capacitance after 1000 cycles) in an aqueous KOH electrolyte. This study demonstrates that there is an optimum level of nitrogen doping required to keep the meso-structure of carbon network intact, simultaneously maintaining high surface area and sufficient electrical conductivity for electrochemical applications.

  13. Synergistic increase of oxygen reduction favourable Fe-N coordination structures in a ternary hybrid of carbon nanospheres/carbon nanotubes/graphene sheets.

    Science.gov (United States)

    Zhang, Shiming; Liu, Bin; Chen, Shengli

    2013-11-14

    A Fe/N co-doped ternary nanocarbon hybrid, with uniform bamboo-like carbon nanotubes (CNTs) in situ grown on/between the single/few-layer graphene sheets interspaced by carbon nanosphere aggregates, was prepared through a one-pot heat treatment of a precursor mixture containing graphene oxide, Vulcan XC-72 carbon nanospheres, nitrogen rich melamine and small amounts of Fe ions. Physical characterization including electron microscopic images, N2 adsorption-desorption isotherms, pore size distribution, XPS, XRD, Mössbauer spectra, and EDX revealed that the 0-D/1-D/2-D ternary hybrid architecture not only offered an optimized morphology for high dispersion of each nanocarbon moiety, while the carbon nanosphere interspaced graphene sheets have provided a platform for efficient reaction between Fe ions and melamine molecules, resulting in uniform nucleation and growth of CNTs and formation of high density Fe-N coordination assemblies that have been believed to be the active centers for the oxygen reduction reaction (ORR) in carbon-based nonprecious metal electrocatalysts. In the absence of graphene oxides or carbon nanospheres, a similar heat treatment was found to result in large amounts of elemental Fe and Fe carbides and entangled CNTs with wide diameter distributions. As a result, the ternary Fe/N-doped nanocarbon hybrid exhibits ORR activity much higher than the Fe-N doped single or binary nanocarbon materials prepared under similar heat treatment conditions, and approaching that of the state-of-the-art carbon-supported platinum catalyst (Pt/C) in acidic media, as well as superior stability and methanol tolerance to Pt/C.

  14. A survey on trace organic chemicals in a German water protection area and the proposal of relevant indicators for anthropogenic influences.

    Science.gov (United States)

    Seitz, Wolfram; Winzenbacher, Rudi

    2017-06-01

    A comprehensive monitoring programme of trace organic chemicals (TOrC) was conducted for a German water protection area in karstic ground. The aim of this survey was to detect the potential anthropogenic influences of point sources such as wastewater treatment plants and diffuse pollution such as runoff water from roads on the raw water used for drinking water treatment. The programme comprised seven sampling campaigns within 2 years each with up to 20 sampling sites. In total, the programme included 84 anthropogenic compounds from pharmaceuticals, iodinated X-ray contrast media, sweeteners, industrial chemicals (benzotriazoles, melamines and benzothiazoles) and pesticide metabolites. Cyclamate occurred with the highest median concentration of 44 μg l -1 in untreated wastewater and acesulfame occurred with a concentration of 20 μg l -1 in treated wastewater. In runoff water from roads, the most relevant compounds were tolyltriazole with 2.3 μg l -1 and the desphenyl-chloridazon with 1.2 μg l -1 . In the stream waters, the highest median concentrations were found for melamine and acesulfame both at 0.61 μg l -1 . High elimination during conventional wastewater treatment was observed for 5 out of 49 compounds. These are acetyl-sulfamethoxazole, aciclovir, cyclamate, ibuprofen and saccharin. Based on the survey results, we propose a set of nine compounds to be used as indicators for wastewater, untreated wastewater and runoff water from roads for an efficient surveillance. The indicators are intended to detect anthropogenic influences in surface, ground and drinking water.

  15. Adhesive bond performance of heat-treated wood at various conditions.

    Science.gov (United States)

    Kol, Hamiyet Sahin; Özbay, Günay

    2016-07-01

    Heat treatment of wood leads to chemical, structural and physical changes in wood constituents, which can significantly affect the bonding performance of wood in several ways depending on the adhesive type used. In the present study, fir (Abies bornmülleriana Mattf.) and beech (Fagus orientalis L.) were heat treated at 170 degrees C, 180 degrees C, 190 degrees C, 200 and 212 degrees C for 2 hours. Four different types of adhesives were used for bonding process: melamine-urea-formaldehyde (MUF), melamine formaldehyde (MF), phenol formaldehyde (PF), and polyurethane (PUR). For all the pretreatment conditions, highest shear strength of adhesive bonds of each adhesive system was observed for untreated samples and shear strength decreased with increasing heat treatment. The strength of each adhesive bond of samples which were soaked in water was much less than dry samples, approximately half of the dry strength. Generally, the shear strength of the adhesive bonds after boiling was smaller than or similar to the values obtained for soaking. The untreated samples lost more strength after soaking and boiling than heat treated samples. With increasing heat treatment severity, reduction in shear strength increased in dry samples while decreased in soaking and boiling samples. For instance, after soaking, the untreated samples lost more strength (almost 39%) than heat treated samples (almost 24% for most severely heat treated samples). The results showed that the shear strength of adhesive bonds was influenced by heat treatment and depended on pretreatment of samples prior to testing. In general, all adhesives used performed in quite a similar way for all pretreatment conditions, and the bonding performance of heat treated fir wood was less satisfactory than that of beech wood for all adhesive system and condition.

  16. Novel antimicrobial textiles

    Science.gov (United States)

    Cho, Unchin

    2003-10-01

    Many microorganisms can survive, and perhaps proliferate on textiles, generating adverse effects such as: disease transmission, odor generation, pH changes, staining, discoloration and loss of performance. These adverse effects may threaten users' health, deteriorate textile properties and degrade service quality. It may, therefore, be desirable to incorporate antimicrobials on textiles for controlling the growth of microorganisms. This dissertation focuses on the development of antimicrobial fibers and fabrics by integration of antimicrobials with these textiles. The applications of hydantoin-based halamines were mainly investigated in the research. The typical process is that hydantoin containing compounds are grafted onto textiles and transformed to halamine by chlorination. Hydantoin-based halamines are usually chloramines that release chlorine (Cl+) via cleavage of the -NCl functional group which attacks and kills microbes. The antimicrobial behavior is rechargeable many times by rinsing the fiber or fabric with chlorine-containing solution. Some quaternary ammonium type antimicrobials were also investigated in this research. The choice of integrating techniques is dependant on both the textile and antimicrobial compounds. In this dissertation, the nine approaches were studied for incorporating antimicrobial with various textiles: (1) co-extrusion of fibers with halamine precursor additive; (2) grafting of the quaternary ammonium compounds onto ethylene-co-acrylic acid fiber for creating quaternary ammonium type antimicrobial fiber; (3) entrapment of the additives in thermally bonded bicomponent nonwoven fabrics; (4) attaching antimicrobial additives to surfaces with latex adhesive coating; (5) grafting of antimicrobial compounds onto rubber latex via UV exposure; (6) reaction of halamine with needle-punched melamine formaldehyde nonwoven fabric and laminates; (7) coating melamine resin onto tent fabrics and laminates; (8) synthesis of super absorbent polymer

  17. Electron transfer number control of the oxygen reduction reaction on nitrogen-doped reduced graphene oxides for the air electrodes of zinc-air batteries and organic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Sheng-Hui; Li, Po-Chieh; Hu, Chi-Chang, E-mail: cchu@che.nthu.edu.tw

    2016-11-01

    The mean electron transfer number (n) of the oxygen reduction reaction (ORR) on reduced graphene oxide (rGO) is controlled by nitrogen doping for the air electrodes of Zn-air batteries and electrochemical organic degradation. Melamine and pyrrole are employed as the nitrogen sources for fabricating N-doped rGO (N-rGO) by microwave-assisted hydrothermal synthesis (MAHS). The n value of the ORR is determined by the rotating ring-disk electrode (RRDE) voltammetry and is successfully controlled from 2.34 to 3.93 by preparation variables. The N-doped structures are examined by the x-ray photoelectron spectroscopic (XPS) analysis. The morphology and the defect degree of N-rGOs are characterized by high resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy. N-rGOs with high and low n values are employed as the air electrode catalysts of zinc-air batteries and in-situ hydrogen peroxide (H{sub 2}O{sub 2}) generation, respectively. The highest discharge cell voltage of 1.235 V for a Zn-air battery is obtained at 2 mA cm{sup −2} meanwhile the current efficiency of H{sub 2}O{sub 2} generation in 1-h electrolysis at 0 V (vs. RHE) reaches 43%. The electrocatalytic degradation of orange G (OG), analyzed by UV-VIS absorption spectra, reveals a high decoloration degree from the relative absorbance of 0.38 for the azo π-conjugation structure of OG. - Highlights: • The mean electron transfer number (n) is controlled by nitrogen doping. • Melamine and pyrrole are used as the nitrogen sources for fabricating N-rGO. • The n value is successfully controlled from 2.34 to 3.93 by preparation variables. • The highest discharge cell voltage of 1.235 V for a Zn-air battery. • The current efficiency of H{sub 2}O{sub 2} generation 1-h electrolysis reaches 43%.

  18. Graphitic carbon nitride: Synthesis, characterization and photocatalytic decomposition of nitrous oxide

    Energy Technology Data Exchange (ETDEWEB)

    Praus, Petr, E-mail: petr.praus@vsb.cz [Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Department of Chemistry, Faculty of Metallurgy and Materials Engineering, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Svoboda, Ladislav [Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Department of Chemistry, Faculty of Metallurgy and Materials Engineering, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Ritz, Michal [Department of Chemistry, Faculty of Metallurgy and Materials Engineering, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Troppová, Ivana; Šihor, Marcel; Kočí, Kamila [Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic)

    2017-06-01

    Graphitic carbon nitride (g-C{sub 3}N{sub 4}) was synthetized by condensation of melamine at the temperatures of 400–700 °C in air for 2 h and resulting products were characterized and finally tested for the photocatalytic decomposition of nitrous oxide. The characterization methods were elemental analysis, UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), Fourier transform infrared (FTIR) and Raman spectroscopy, measurement of specific surface area (SSA), X-ray powder diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopy. The XRD patterns, FTIR and Raman spectra proved the presence of g-C{sub 3}N{sub 4} at above 550 °C but the optimal synthesis temperature of 600–650 °C was found. Under these conditions graphitic carbon nitride of the overall empirical composition of C{sub 6}N{sub 9}H{sub 2} was formed. At lower temperatures g-C{sub 3}N{sub 4} with a higher content of hydrogen was formed but at higher temperatures g-C{sub 3}N{sub 4} was decomposed. At the temperatures above 650 °C, its exfoliation was observed. The photocatalytic experiments showed that the activity of all the samples synthetized at 400–700 °C was very similar, that is, within the range of experimental error (5 %). The total conversion of N{sub 2}O reached about 43 % after 14 h. - Highlights: • Graphitic carbon nitride (g-C{sub 3}N{sub 4}) was thermally synthetized from melamine in the range of 400–700 °C. • The optimal temperature was determined at 600–650 °C. • All synthesis products were properly characterized by physico-chemical methods. • Exfoliation of g-C{sub 3}N{sub 4} at above 600 °C was observed. • g-C{sub 3}N{sub 4} was used for the photocatalytic decomposition of N{sub 2}O.

  19. Preparation of three-dimensional nitrogen-doped graphene layers by gas foaming method and its electrochemical capactive behavior

    International Nuclear Information System (INIS)

    Hao, Junnan; Shu, Dong; Guo, Songtao; Gao, Aimei; He, Chun; Zhong, Yayun; Liao, Yuqing; Huang, Yulan; Zhong, Jie

    2016-01-01

    Highlights: • A three-dimensional porous graphene layers was prepared via a gas foaming method. • Melamine was the nitrogen source to synthesize the N-doped 3D graphene layers. • The specific surface area of 3D N-doped graphene material is as high as 1196 m 2 g −1 . • The 3D N-doped graphene specific capacitance is 335 F g −1 in three-electrode system. • The energy density of 3D N-doped graphene reaches 58.1 Wh kg −1 in a symmetric cell. - Abstract: A porous graphene layers with a three-dimensional structure (3DG) was prepared via a gas foaming method based on a polymeric predecessor. This intimately interconnected 3DG structure not only significantly increases the specific surface area but also provides more channels to facilitate electron transport. In addition, 3D N-doped (3DNG) layers materials were synthesized using melamine as a nitrogen source. The nitrogen content in the 3DNG layers significantly influenced the electrochemical performance. The sample denoted as 3DNG-2 exhibited a specific capacitance of 335.2 F g −1 at a current density of 1 A g −1 in a three-electrode system. Additionally, 3DNG-2 exhibited excellent electrochemical performance in aqueous and organic electrolytes using a two-electrode symmetric cell. An energy density of 58.1 Wh kg −1 at a power density of 2500 W kg −1 was achieved, which is approximately 3 times that (19.6 Wh kg −1 ) in an aqueous electrolyte in a two-electrode system. After 1000 cycles, the capacity retention in aqueous electrolyte was more than 99.0%, and this retention in organic electrolytes was more than 89.4%, which demonstrated its excellent cycle stability. This performance makes 3DNG-2 a promising candidate as an electrode material in high-power and high-energy supercapacitor applications.

  20. Creep of MDF panels under constant load and cyclic environmental conditions. Influence of surface coating

    Directory of Open Access Journals (Sweden)

    Fernández-Golfín, J. I.

    1997-06-01

    Full Text Available Four different strategies of surface coating (based on 80 g m2 melamin impregnated papers were used on 19 mm thick commercial MDF panels to assess its reological behaviour under cyclic humidity conditions (20ºC 30 % rh-20ºC 90 % rh. Three different levels of stress (20 %, 30 % and 40 %, based on the ultimate load in bending, were used. Tests were conducted by means of the three points load system. For the same stress level, the relative creep of MDF panels was higher than that in particle boards with similar characteristics. This behaviour was just the opposite than the one exhibited by the panels when the comparison is made based on the same level of load (kg Melamin coating seems to strongly influence the creep behaviour of the raw material, especially when surface and edge coating were combined.

    Cuatro tipos de acabados superficiales distintos, aplicados sobre tableros MDF comerciales de 19 mm de espesor, son empleados en el estudio del comportamiento reológico de los tableros MDF ante condiciones alternantes de humedad relativa (20ºC/30 % hr-20ºC/90 % hr. Para el análisis del comportamiento reológico de los tableros se consideran tres niveles de tensión distintos (20 %, 30 %y 40 %, calculados en función de la carga última de rotura a flexión. Los ensayos son efectuados aplicando la carga en punto medio. La fluencia relativa de los tableros MDF resulta ser superior a la exhibida por los tableros de partículas de similares características, observándose que los revestimientos melamínicos aplicados superficialmente influyen eficazmente en la mejora de su comportamiento reológico. Cuando la comparación entre tableros MDF y de partículas se efectúa considerando idénticos niveles de carga aplicada en vez de tensión, el resultado de la comparación resulta ser, justamente, el contrario.

  1. Enhanced visible-light photoactivity of g-C{sub 3}N{sub 4} via Zn{sub 2}SnO{sub 4} modification

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lihong; Wang, Xiaoxing; Nong, Qingyan [Department of Materials Physics, Zhejiang Normal University, Jinhua 321004 (China); Lin, Hongjun [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Teng, Botao [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Zhang, Yuting [Department of Materials Physics, Zhejiang Normal University, Jinhua 321004 (China); Zhao, Leihong; Wu, Tinghua [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); He, Yiming, E-mail: hym@zjnu.cn [Department of Materials Physics, Zhejiang Normal University, Jinhua 321004 (China)

    2015-02-28

    Highlights: • Novel Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composites are prepared via calcination of Zn{sub 2}SnO{sub 4} and melamine. • Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composite degrades RhB 3.2 times faster than g-C{sub 3}N{sub 4}. • The synergetic effect of Zn{sub 2}SnO{sub 4} and g-C{sub 3}N{sub 4} is the origin of the high photoactivity. - Abstract: The objective of this research was to prepare, characterize and evaluate the photocatalytic activity of Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composite in RhB degradation under visible light irradiation. The composite was synthesized by simple calcination of Zn{sub 2}SnO{sub 4}–melamine mixture, and was characterized by various techniques including Brunauer–Emmett–Teller method (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). Characterization results indicated that the decoration of Zn{sub 2}SnO{sub 4} on g-C{sub 3}N{sub 4} showed nearly no effect on its light absorption performance, but promoted the surface area of the composite, which benefited the adsorption of dyes and the subsequent photocatalytic process. However, more significant was the formation of hetero-junction structure between Zn{sub 2}SnO{sub 4} and g-C{sub 3}N{sub 4}, which efficiently promoted the separation of electron–hole pairs and enhanced the photocatalytic performance of Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4}. The optimal Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} photocatalyst showed a degradation rate of 0.038 min{sup −1}, which was 3.2 times higher than that of g-C{sub 3}N{sub 4}. In addition, the Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composite shows high stability. ·O{sub 2}{sup −} and h{sup +} were the main reactive species.

  2. Etiology and outcomes of acute kidney injury in Chinese children: a prospective multicentre investigation.

    Science.gov (United States)

    Cao, Yan; Yi, Zhu-Wen; Zhang, Hui; Dang, Xi-Qiang; Wu, Xiao-Chuan; Huang, Ai-Wen

    2013-08-21

    The incidence of AKI appears to have increasing trend. Up to now, prospective, multi-center, large-sample epidemiological study done on pediatric AKI on aspects of epidemiological characteristics, causes and outcomes have not reported. It is necessary to develop prospective, multi-center, large-sample epidemiological study in our country on pediatric AKI. The aim of this study was to determine the clinical features, etiology, and outcomes of acute kidney injury (AKI) in Chinese children. Paediatric patients (≤18 years old) admitted to 27 hospitals (14 children's hospitals and 13 general hospitals) affiliated with the Medical University were investigated. AKI was defined using the 2005 Acute Kidney Injury Network criteria. During the study period, 388,736 paediatric patients were admitted. From this total, AKI was diagnosed in 1,257 patients, 43 of whom died. The incidence and mortality of AKI was 0.32% and 3.4% respectively. The mean (± SD) age of patients was 48.4 ± 50.4 months. Among the 1,257 AKI paediatric patients, 632 were less than one year old. Among the AKI paediatric patients, 615 (48.9%) were in stage 1, 277 (22.0%) in stage 2, and 365 (29.0%) in stage 3. The most common causes of AKI were renal causes (57.52%), whereas postrenal (25.69%) and prerenal (14.96%) causes were the least common. The three most common causes of AKI according to individual etiological disease were urolithiasis (22.35%), of which exposure to melamine-contaminated milk accounted for the highest incidence (63.7%); acute glomerulonephritis (10.10%); and severe dehydration (7.48%). A total of 43 AKI patients (3.4%) died during their hospital stay; 15 (34.9%) of the 43 died as a result of sepsis. Primary renal diseases are a major risk factor for paediatric AKI in China. In terms of specific etiological disease, urolithiasis (postrenal disease) was the leading cause of paediatric AKI in 2008, when the disease was linked to exposure to melamine-contaminated milk. Sepsis is the

  3. The novel silicon-containing epoxy/PEPA phosphate flame retardant for transparent intumescent fire resistant coating

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yanchao [School of Materials Science and Engineering, Tongji University, 4800 Cao' an Road, Shanghai 201804 (China); Wang, Guojian, E-mail: wanggj@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, 4800 Cao' an Road, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, 4800 Cao' an Road, Shanghai 201804 (China)

    2016-11-01

    Highlights: • The novel halogen-free flame retardant containing silicon and caged bicyclic phosphate was synthesized. • A novel transparent intumescent fire resistant coating was developed by the P-Si synergistic flame retardant and melamine formaldehyde resin. • Excellent fire protection of the transparent intumescent fire resistant coating. • The P-Si synergistic flame retardant could improve the thermo-oxidation resistance of transparent fire resistant coating. - Abstract: A series of novel silicon-containing epoxy/PEPA phosphate flame retardants (EPPSi) were synthesized by polyphosphoric acid (PPA), caged bicyclic phosphate 1-oxo-4-hydroxymethyl-2,6,7-trioxa-L-phosphabicyclo [2.2.2] octane (PEPA), and different ratios of silicon-containing epoxy 1,1,3,3-tetramethyl-1,3-bis(3-(oxiran-2-ylmethoxy)propyl)disiloxane (TMSEP) to 1,4-butanediol diglycidyl ether (BDE). The chemical structure of EPPSi was confirmed by Fourier transform infrared spectroscopy (FTIR) and {sup 1}H nuclear magnetic resonance spectroscopy ({sup 1}H NMR). Afterwards, the transparent intumescent fire resistant coatings were prepared by mixing EPPSi and melamine formaldehyde resin. The influence of silicon on the fire protection of coatings was intensively investigated by fire protection test, intumescence ratio, scanning electron microscope (SEM), compressive strength test, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and real-time FTIR. It was found that the fire resistant coatings obtained the best fire protection when the ratio of TMESP/BDE was 20/100, while excessive TMSEP made the fire protection of coatings deceased sharply. The intumescence ratio, compressive strength test and SEM result showed that a synergistic effect existed between phosphorus and silicon, which improved the foam structure and compressive strength of the char layer significantly. XPS result proved the out-migration effect of silicon. The high concentration silicon on surface played

  4. Potential harmful effects of dietary supplements in sports medicine.

    Science.gov (United States)

    Deldicque, Louise; Francaux, Marc

    2016-11-01

    The purpose of this article is to collect the most recent data regarding the safety of well-known or emerging dietary supplements used by athletes. From January 2014 to April 2016, about 30 articles have been published in the field. New data show that 90% of sports supplements contain trace of estrogenic endocrine disruptors, with 25% of them having a higher estrogenic activity than acceptable. About 50% of the supplements are contaminated by melamine, a source of nonprotein nitrogen. Additional data accumulate toward the safety of nitrate ingestion. In the last 2 years, the safety of emerging supplements such as higenamine, potentially interesting to lose weight, creatine nitrate and guanidinoacetic acid has been evaluated but still needs further investigation. The consumption of over-the-counter supplements is very popular in athletes. Although most supplements may be considered as safe when taking at the recommended doses, athletes should be aware of the potential risks linked to the consumption of supplements. In addition to the risks linked to overdosage and cross-effects when combining different supplements at the same time, inadvertent or deliberate contamination with stimulants, estrogenic compounds, diuretics or anabolic agents may occur.

  5. Rapid turbidimetric detection of milk powder adulteration with plant proteins.

    Science.gov (United States)

    Scholl, Peter F; Farris, Samantha M; Mossoba, Magdi M

    2014-02-19

    Development of assays to screen milk for economically motivated adulteration with foreign proteins has been stalled since 2008 due to strong international reactions to the melamine poisoning incident in China and the surveillance emphasis placed on low molecular weight nitrogen-rich adulterants. New screening assays are still needed to detect high molecular weight foreign protein adulterants and characterize this understudied potential risk. A rapid turbidimetric method was developed to screen milk powder for adulteration with insoluble plant proteins. Milk powder samples spiked with 0.03-3% by weight of soy, pea, rice, and wheat protein isolates were extracted in 96-well plates, and resuspended pellet solution absorbance was measured. Limits of detection ranged from 100 to 200 μg, or 0.1-0.2% of the sample weight, and adulterant pellets were visually apparent even at ∼0.1%. Extraction recoveries ranged from 25 to 100%. Assay sensitivity and simplicity indicate that it would be ideally suitable to rapidly screen milk samples in resource poor environments where adulteration with plant protein is suspected.

  6. Major food safety episodes in Taiwan: Implications for the necessity of international collaboration on safety assessment and management

    Directory of Open Access Journals (Sweden)

    Jih-Heng Li

    2012-07-01

    Full Text Available The major food safety episodes that occurred in Taiwan during the past decade are briefly reviewed in this paper. Among the nine major episodes surveyed, with the exception of a U.S. beef (associated with Creutzfeldt–Jakob disease-related incident, all the others were associated with chemical toxicants. The general public, which has a layperson attitude of zero tolerance toward food safety, may panic over these food-safety-associated incidents. However, the health effects and impacts of most incidents, with the exception of the melamine incident, were essentially not fully evaluated. The mass media play an important role in determining whether a food safety concern becomes a major incident. A well-coordinated and harmonized system for domestic and international collaboration to set up standards and regulations is critical, as observed in the incidents of pork with ractopamine, Chinese hairy crab with nitrofuran antibiotics, and U.S. wheat with malathion. In the future, it can be anticipated that food safety issues will draw more attention from the general public. For unknown new toxicants or illicit adulteration of food, the establishment of a more proactive safety assessment system to monitor potential threats and provide real-time information exchange is imperative.

  7. Highly efficient oil-in-water emulsion and oil layer/water mixture separation based on durably superhydrophobic sponge prepared via a facile route.

    Science.gov (United States)

    Wang, Jintao; Wang, Hongfei; Geng, Guihong

    2018-02-01

    The fabrication of the materials with special wettability being capable of removing oil layer on water surface and oil droplets in oil-in-water emulsion is an important issue for water pollution. So far, it still remains challenging to explore a simple, facile, environmentally friendly approach for achieving this goal. Herein, inspired by the adhesion of marine mussels, the polydopamine (PDA) coating with hierarchical structure was directly fabricated onto the surface of melamine (MF) sponge by facile self-polymerization in dopamine solution. Then, a superhydrophobic and superoleophilic sponge was successfully obtained after the modification by dodecanethiol (DDT) at ambient temperature. The as-prepared sponge can selectively separate a series of oil droplets in oil-in-water emulsion with high efficiency (transparency: 76.6-93.8%) and absorb various oils or organic solvents up to 45.2-98.6 times of its own weight. Moreover, in conjunction with a vacuum system, great amounts of oils up to 20 times its own weight can be effectively separated from water surface within 1s by the sponge. Due to low cost, simple process, and easy accessibility, the as-prepared sponge has potential applications in oil-in-water emulsion separation and oil spill cleanup. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Beam test results of CMS RPCs at high eta region under high-radiation environment

    CERN Document Server

    Park, S; Bahk, S Y; Hong, B; Hong, S J; Kang, D H; Kang, T I; Kim, T J; Kim, Y J; Kim, Y U; Koo, D G; Lee, H W; Lee, K S; Lee, S J; Lim, J K; Moon, D H; Nam, S K; Oh, J K; Park, W J; Rhee, J T; Ryu, M S; Shim, H H; Sim, K S

    2004-01-01

    The Compact Muon Solenoid (CMS) forward resistivity plate chambers (RPCs) at the high eta region must be operated in presence of a radiation-induced rate as high as 1 kHz/cm**2. It is still unknown if the RPCs coated with linseed oil can be operated under such a high- radiation environment over the lifetime of CMS. Non-oiled RPCs may be one of the options since phenolic or melamine-coated bakelite is chemically stabler than linseed oil. We have constructed oiled and non-oiled RPCs at the high eta region of CMS using phenolic bakelite and tested them in the Gamma Irradiation Facility at CERN. While both RPCs show the same characteristics in the efficiency and the strip multiplicity, the non-oiled RPC generates an intrinsic noise rate of 50 Hz/cm**2, compared to only 5 Hz/cm**2 for the oiled RPC, both at 10.0kV which is about 100 V above the 95% knee of the efficiency curve.

  9. Easy dispersion and excellent visible-light photocatalytic activity of the ultrathin urea-derived g-C3N4 nanosheets

    Science.gov (United States)

    Yang, Yuxin; Geng, Lei; Guo, Yingna; Meng, Jiaqi; Guo, Yihang

    2017-12-01

    Ultrathin two-dimensional (2D) g-C3N4 nanosheets (UCNS) are facilely prepared by liquid-exfoliation of the urea-derived g-C3N4via an HCl-assisted hydrothermal treatment method. The UCNS are served as the novel visible-light-driven photocatalyst to degrade a typical organic pollutant, p-nitrophenol (PNP), in an aqueous solution. By the combination of the advantages of plentiful exposed active sites, fast photogenerated charge carrier separation rate, aligned energy levels and easy dispersion in an aqueous solution, the UCNS exhibit considerably enhanced visible-light photocatalytic activity toward the degradation of the target compound in comparison of their bulk g-C3N4 counterpart, melamine-derived g-C3N4 nanoparticles or Degussa P25 TiO2. The indirect chemical probe experimental results indicate that both the superoxide radicals and the photogenerated holes are responsible for the complete decomposition of PNP. Additionally, the UCNS can be reused at least four times without obvious activity loss and morphology change, exhibiting the excellent reusability in photodegradation aqueous organic pollutants.

  10. High-yield synthesis and optical properties of g-C3N4.

    Science.gov (United States)

    Yuan, Yanwen; Zhang, Lulu; Xing, Jun; Utama, M Iqbal Bakti; Lu, Xin; Du, Kezhao; Li, Yongmei; Hu, Xiao; Wang, Shijie; Genç, Aziz; Dunin-Borkowski, Rafal; Arbiol, Jordi; Xiong, Qihua

    2015-08-07

    Graphitic carbon nitride (g-C3N4), a metal-free semiconductor with a band gap of 2.7 eV, has received considerable attention owing to its fascinating photocatalytic performances under visible-light. g-C3N4 exhibits high thermal and chemical stability and non-toxicity such that it has been considered as the most promising photocatalyst for environmental improvement and energy conservation. Hence, it is of great importance to obtain high-quality g-C3N4 and gain a clear understanding of its optical properties. Herein, we report a high-yield synthesis of g-C3N4 products via heating of high vacuum-sealed melamine powder in an ampoule at temperatures between 450 and 650 °C. Using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the chemical composition and crystallization of the as-produced g-C3N4 are demonstrated. A systematic optical study of g-C3N4 is carried out with several approaches. The optical phonon behavior of g-C3N4 is revealed by infrared and Raman spectroscopy, and the emission properties of g-C3N4 are investigated using photoluminescence (PL) spectroscopy, while the photocatalytic properties are explored by the photodegradation experiment.

  11. Photocatalytic activities of coke carbon/g-C3N4 and Bi metal/Bi mixed oxides/g-C3N4 nanohybrids for the degradation of pollutants in wastewater

    Science.gov (United States)

    Sierra, Marta; Borges, Emma; Esparza, Pedro; Méndez-Ramos, Jorge; Martín-Gil, Jesús; Martín-Ramos, Pablo

    2016-01-01

    Abstract Different g-C3N4 composite systems (coke carbon/g-C3N4, Bi/Bi2WO6/g-C3N4 and Bi/Bi2MoO6/g-C3N4) have been assessed as photocatalysts for wastewater pollutants removal. The coke carbon/g-C3N4 hybrid, produced by thermal treatment at 550 °C of a composite made from melamine cyanurate and coke, only showed activity under UV-light irradiation. On the other hand, inorganic Bi spheres/Bi mixed oxides/g-C3N4 nanohybrids (Bi/Bi2WO6/g-C3N4 and Bi/Bi2MoO6/g-C3N4 composites), produced by thermal reduction of Bi2WO6 or Bi2MoO6 by g-C3N4, exhibited a remarkable red-shift, up to 620 nm, and allowed the visible-light driven degradation of the contaminant, albeit in combination with some adsorption. PMID:27877912

  12. FAO/IAEA International Symposium on Food Safety and Quality: Applications of Nuclear and Related Techniques, Vienna, Austria, 10−13 November 2014

    International Nuclear Information System (INIS)

    2015-01-01

    Ensuring food supply integrity is of the utmost importance in relation to food security, safety and quality, consumer protection and international trade. Control measures throughout the entire food production and supply chain are essential to maintain and assure this integrity. The fundamental purpose of the controls is to support food safety and quality, because both are essential and set the foundation for food security and consumer protection as well as facilitating both domestic and international trade. The need for methods to monitor and verify food safety and quality is evidenced by the ever growing list of food product recalls and incidents such as melamine, antibiotic and dioxin contamination. Food fraud (e.g. the adulteration of beef products with horse meat), the introduction of new technologies with potential food safety implications (e.g. nanotechnology) and environmental factors (e.g. climate change) further highlight the importance of continued refinement, development and innovation to improve food control measures. Effective techniques are necessary to help assess and manage risks and protect the consumer. These include food irradiation to treat food directly, as well as other nuclear and related technologies for tracing food products in order to verify their provenance or to detect and control contaminants. To explore some of these challenges experienced by many Member States, an International Symposium on Food Safety and Quality: Applications of Nuclear and Related Techniques was held in Vienna, Austria, from 10 to 13 November 2014, under the auspices of the Food and Environmental Protection Subprogramme.

  13. Synthesis of cyclotriphosphazene-containing polymeric nanotubes and their use as metal-free photocatalysts for methylene blue degradation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhenke, E-mail: aq09zkli@outlook.com [College of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan 430081 (China); College of Chemistry and Materials, South-Central University for Nationalities, Wuhan 430074 (China); Wang, Guanghui, E-mail: wghwang@263.net [College of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan 430081 (China); Liang, Chen, E-mail: 401139655@qq.com [College of Chemistry and Materials, South-Central University for Nationalities, Wuhan 430074 (China); Zhang, Aiqing, E-mail: aiqingzhang_2000@sina.com [College of Chemistry and Materials, South-Central University for Nationalities, Wuhan 430074 (China)

    2015-08-30

    Highlights: • Polyphosphazene nanotubes were synthesized by a simple approach without any surfactants or template agents. • The nanotubes own numerous electron-rich N and P atoms and amino groups. • These nanotubes showed excellently photocatalyst performance for the degradation MB. • Polyphosphazene nanotubes as metal-free catalyst were similar with semiconductor materials. - Abstract: Highly cross-linked, organic–inorganic hybrid polymer nanotubes with primary amine groups on the surface have been successfully prepared through a facile polycondensation of hexachlorocyclotriphosphazene and melamine in absence of any surfactants or template agents. Then, these nanotubes were used as visible light photocatalysts for the degradation of methylene blue (MB) in water and the physicochemical properties of catalysts were characterized by several techniques. The as-synthesized nanotubes were closed at one end with a micrometer-scale in length (about 3–10 μm), 200–300 nm in the diameter, and the inner diameters of the two ends of each nanotube was 100–200 nm and 5–10 nm, respectively. A large amount of free radicals (·OH) were generated in aqueous phase under visible light irradiation, which can photocatalytically oxidize and eventually mineralize. And, the progress of degradation was similar with semiconductor materials. The simple preparation method and photocatalytic performance of the cyclotriphosphazene-containing polymeric nanotubes represent an important step towards photocatalytic reaction in general where artificial conjugated polymer semiconductors can be used as energy transducers.

  14. Facile synthesis of reduced graphene oxide-modified, nitrogen-doped carbon xerogel with enhanced electrochemical capacitance

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Gang [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Hu, Xiaoyong [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Peng, Zhiguang [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Hu, Jiawen, E-mail: jwhu@hnu.edu.cn [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Liu, Hongtao, E-mail: liuht@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2014-12-15

    In this contribution, we report a reduced graphene oxide (rGO)-modified nitrogen-doped carbon xerogel, which could be easily prepared by pyrolysis of melamine-formaldehyde (MF) resins that are polymerized hydrothermally in an aqueous GO dispersion. Scanning electron microscopy, transmission electron microscopy, Fourier-transformed infrared spectrometry, and nitrogen adsorption-desorption method were employed to reveal the morphologies and structures of the prepared carbon xerogel. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge were used to investigate the electrochemical properties. The results showed that the charge transfer barrier of the mesoporous nitrogen-doped carbon xerogel was decreased evidently, owing to the modification of a layer of rGO on its wall, and the xerogel demonstrated a capacitance of as high as 205 F g{sup −1} at the current of 1 A g{sup −1}. - Graphical abstract: A facile synthesis of rGO-modified, N-doped carbon material for supercapacitor application. - Highlights: • Nitrogen-doping and graphene-attachment in the carbon material are simultaneously achieved. • A thin layer of graphene attached on the wall of the mesoporous carbon material speeds up the charge transfer. • The graphene-modified nitrogen-doped carbon xerogel shows great potential for supercapacitor application.

  15. Graphitic g-C{sub 3}N{sub 4}-WO{sub 3} Composite: Synthesis and Photocatalytic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Doan, An Tran; Thi, Xuan Dieu Nguyen; Nguyen, Phi Hung; Thi, Viet Nga Nguyen; Vo, Vien [Quy Nhon Univ., Quy Nhon (Viet Nam); Kim, Sung Jin [Ewha Womans Univ., Seoul (Korea, Republic of)

    2014-06-15

    Graphitic g-C{sub 3}N{sub 4}-WO{sub 3} composite was synthesized simply by decomposing melamine in the presence of WO{sub 3} at 500 .deg. C. The obtained material was characterized by XRD, SEM, IR and XPS. The results showed that the as-prepared composite exhibits orthorhombic WO{sub 3} phase coated by g-C{sub 3}N{sub 4} and the g-C{sub 3}N{sub 4} decomposed completely with N-doped WO{sub 3} remaining at elevated calcination temperatures. The photocatalytic activity of the composite was evaluated by the photodegradation of methylene blue under visible light. An enhancement in photocatalytic activity for the graphitic g-C{sub 3}N{sub 4}-WO{sub 3} composite compared to the conventional nitrogen-doped WO{sub 3} was observed, which can be attributed to the presence of g-C{sub 3}N{sub 4} in the material.

  16. Enhancing anti-microbial properties of wood-plastic composites produced from timber and plastic wastes.

    Science.gov (United States)

    Wang, Lei; Chen, Season S; Tsang, Daniel C W; Poon, Chi Sun; Ok, Yong Sik

    2017-05-01

    Considering the resource waste and environmental burden for timber and plastic materials ending up at landfills, this study proposed upcycling wood and plastic waste into value-added wood-plastic composites (WPCs), complying with the standard requirements of flexural strength, thickness swelling, water absorption and thermal insulation. Biological deterioration is a major concern of WPCs. Bacterial survival, fungal attack and algal growth of bactericide-treated WPCs were holistically analysed. Melamine resin was adopted for impregnating anti-microbial agents on the surface. All the agents showed excellent bactericidal rate (Escherichia coli), yet poly-diallyl-dimethyl-ammonium chloride (PolyDADMAC) and silver had the lowest minimum inhibitory concentrations. In terms of weight loss and strength reduction due to fungal decay (Coriolus versicolor), PolyDADMAC, silver and cetyltrimethylammonium bromide (CTAB) imparted the highest resistance on the WPCs. Moreover, PolyDADMAC and copper provided the most protection against algal growth (Chlorella vulgaris), and the former presented durable inhibitory effect. This study presents a value-added solution to wood/plastic waste recycling.

  17. TLC-SERS Plates with a Built-In SERS Layer Consisting of Cap-Shaped Noble Metal Nanoparticles Intended for Environmental Monitoring and Food Safety Assurance

    Directory of Open Access Journals (Sweden)

    H. Takei

    2015-01-01

    Full Text Available We report on a thin layer chromatograph (TLC with a built-in surface enhanced Raman scattering (SERS layer for in-situ identification of chemical species separated by TLC. Our goal is to monitor mixture samples or diluted target molecules suspended in a host material, as happens often in environmental monitoring or detection of food additives. We demonstrate that the TLC-SERS can separate mixture samples and provide in-situ SERS spectra. One sample investigated was a mixture consisting of equal portions of Raman-active chemical species, rhodamine 6 G (R6G, crystal violet (CV, and 1,2-di(4-pyridylethylene (BPE. The three components could be separated and their SERS spectra were obtained from different locations. Another sample was skim milk with a trace amount of melamine. Without development, no characteristic peaks were observed, but after development, a peak was observed at 694 cm−1. Unlike previous TLC-SERS whereby noble metal nanoparticles are added after development of a sample, having a built-in SERS layer greatly facilitates analysis as well as maintaining high uniformity of noble metal nanoparticles.

  18. Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

    Science.gov (United States)

    Aziz, Hammad; Ahmad, Faiz; Yusoff, P. S. M. Megat; Zia-ul-Mustafa, M.

    2015-07-01

    Intumescent fire retardant coating (IFRC) is a passive fire protection system which swells upon heating to form expanded multi-cellular char layer that protects the substrate from fire. In this research work, IFRC's were developed using different flame retardants such as ammonium polyphosphate, expandable graphite, melamine and boric acid. These flame retardants were bound together with the help of epoxy binder and cured together using curing agent. IFRC was then reinforced with nano magnesium oxide and nano alumina as inorganic fillers to study their effect towards fire performance, microstructure and thermal degradation. Small scale fire test was conducted to investigate the thermal insulation of coating whereas fire performance was calculated using thermal margin value. Field emission scanning electron microscopy was used to examine the microstructure of char obtained after fire test. Thermogravimetric analysis was conducted to investigate the residual weight of coating. Results showed that the performance of the coating was enhanced by reinforcement with nano size fillers as compared to non-filler based coating. Comparing both nano size magnesium oxide and nano size alumina; nano size alumina gave better fire performance with improved microstructure of char and high residual weight.

  19. Thermal performance of alumina filler reinforced intumescent fire retardant coating for structural application

    Science.gov (United States)

    Ahmad, Faiz; Ullah, Sami; Farhana Mohammad, Wan; Farth Shariff, M.

    2014-06-01

    In the modern construction, fire safety has significant consideration for the protection of people and assets. Several intumescent fire protection systems are in practice and have constrain of releasing toxic gases on degradation forms an insulating char layer protecting underlying substrate. An intumescent coating expands many times of its thickness on exposure to fire and protect the underlying substrate from fire. This study presents the results of thermal performance of an intumescent fire retardant coating (IFRC) developed for structural application. IFRC was developed using expandable graphite (EG), ammonium poly phosphate (APP) and melamine (MEL), epoxy resin Bisphenol-A (BPA) and hardener triethylenetetramine (TETA) were used as a binder as a curing agent. Char expansion of IFRC was measured by furnace fire test at 450°C, thermal performance was measured using a Bunsen burner at 950°C and temperature of substrate was recorded for 60 min at an interval of two min. Results showed that IFRC containing 3wt% alumina showed char expansion X19. After one hour exposure of coating to heat, substrate temperature recorded was 154°C. X-ray Diffraction (XRD) results showed the presence of high temperature compounds present in the char of coating, considered responsible to reduce the penetration of heat to the substrate.

  20. The bakelite for the RPCs of the experiment CMS

    CERN Document Server

    Altieri, S; Bruno, G; Guida, R; Merlo, M; Ratti, S P; Riccardi, C; Torre, P; Vitulo, P; Mognaschi, E R; Abbrescia, M; Colaleo, A; Iaselli, Giuseppe; Loddo, F; Maggi, M; Marangelli, B; Natali, S; Nuzzo, S; Pugliese, G; Ranieri, A; Romano, F

    2000-01-01

    Results from aging tests on the bakelite used for the CMS RPCs are presented. Samples of melaminic bakelite were exposed to a heavy gamma and neutron radiation. Data on the bulk resistivity were collected while accumulating gamma and neutron doses and particles fluence up to values well beyond those expected in 10 years of RPCs operation in the barrel region of CMS. The test with gamma radiation was performed at the CERN Gamma Irradiation Facility (GIF) with a 20 Ci /sup 137/Cs source. A total absorbed dose of 5 Gy was accumulated during an irradiation period of about one month. The test with both neutron and gamma radiation was held at the Triga Mark II 250 kW reactor located in Pavia. A total of 80 h of exposure were accumulated integrating a neutron and gamma dose of about 80 Gy and a fast neutron fluence of some 10/sup 11/ cm/sup -2/. Experimental data on dose rate in both the test facilities have been compared to simulation output and show a good agreement. (4 refs).