Using the Melamine Contamination of Foods to Enhance the Chemistry Classroom

ERIC Educational Resources Information Center

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…

Plastic Media Blasting Waste Treatments

DTIC Science & Technology

1988-07-01

melamine formaldehyde resin with a Mohr hardness of 4.0. Urea and melamine formaldehydes are highly crosslinked condensation polymers. These two...with either melamine formaldehyde or urea formaldehyde resins , which contain no chlorine. Wet scrubbers followed by demisters are added to remove any...latter problem. NARF chemists believe that methacrylate dust will be more explosive than dust from melamine or urea formaldehyde

Assessment of melamine and cyanuric acid toxicity in cats.

PubMed

Puschner, Birgit; Poppenga, Robert H; Lowenstine, Linda J; Filigenzi, Michael S; Pesavento, Patricia A

2007-11-01

The major pet food recall associated with acute renal failure in dogs and cats focused initially on melamine as the suspect toxicant. In the course of the investigation, cyanuric acid was identified in addition to melamine in the offending food. The purpose of this study was to characterize the toxicity potential of melamine, cyanuric acid, and a combination of melamine and cyanuric acid in cats. In this pilot study, melamine was added to the diet of 2 cats at 0.5% and 1%, respectively. Cyanuric acid was added to the diet of 1 cat at increasing doses of 0.2%, 0.5%, and 1% over the course of 10 days. Melamine and cyanuric acid were administered together at 0%, 0.2%, 0.5%, and 1% to 1 cat per dose group. No effect on renal function was observed in cats fed with melamine or cyanuric acid alone. Cats dosed with a combination were euthanized at 48 hours after dosing because of acute renal failure. Urine and touch impressions of kidneys from all cats dosed with the combination revealed the presence of fan-shaped, birefringent crystals. Histopathologic findings were limited to the kidneys and included crystals primarily within tubules of the distal nephron, severe renal interstitial edema, and hemorrhage at the corticomedullary junction. The kidneys contained estimated melamine concentrations of 496 to 734 mg/kg wet weight and estimated cyanuric acid concentrations of 487 to 690 mg/kg wet weight. The results demonstrate that the combination of melamine and cyanuric acid is responsible for acute renal failure in cats.

Interaction of melamine and di-(2-ethylhexyl) phthalate exposure on markers of early renal damage in children: The 2011 Taiwan food scandal.

PubMed

Wu, Chia-Fang; Hsiung, Chao A; Tsai, Hui-Ju; Tsai, Yi-Chun; Hsieh, Hui-Min; Chen, Bai-Hsiun; Wu, Ming-Tsang

2018-04-01

Melamine and phthalate, mainly di-(2-ethylhexyl) phthalate (DEHP), are ubiquitously present in the general environment. We investigated whether urine melamine levels can modify the relationship between DEHP exposure and markers of early renal damage in children. A nationwide health survey for Children aged ≤12 years possibly exposed to phthalates were enrolled between August 2012 and January 2013. They were administered questionnaires to collect details regarding past DEHP exposure to phthalate-tainted foodstuffs. Urine samples were measured melamine levels, phthalate metabolites and biomarkers of renal damage, including urine microalbumin/creatinine ratio (ACR), N-acetyl-beta-d-glucosaminidase (NAG), and β2-microglobulin. The study included 224 children who had a median urine melamine level (μg/mmol creatinine) of 1.61 ranging 0.18-47.42. Positive correlations were found between urine melamine levels and urine ACR as well as urine NAG levels (both Spearman correlation coefficients r = 0.24, n = 224, p < .001). The higher the past DEHP exposure or urine melamine levels, the higher the prevalence of microalbuminuria. An interaction effect was also found between urine melamine levels and past DEHP exposure on urine ACR. Melamine levels may further modify the effect of past DEHP exposure on urine ACR in children. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

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

PubMed

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.

Detection of melamine in milk powder using MCT-based short-wave infrared hyperspectral imaging system.

PubMed

Lee, Hoonsoo; Kim, Moon S; Lohumi, Santosh; Cho, Byoung-Kwan

2018-06-05

Extensive research has been conducted on non-destructive and rapid detection of melamine in powdered foods in the last decade. While Raman and near-infrared hyperspectral imaging techniques have been successful in terms of non-destructive and rapid measurement, they have limitations with respect to measurement time and detection capability, respectively. Therefore, the objective of this study was to develop a mercury cadmium telluride (MCT)-based short-wave infrared (SWIR) hyperspectral imaging system and algorithm to detect melamine quantitatively in milk powder. The SWIR hyperspectral imaging system consisted of a custom-designed illumination system, a SWIR hyperspectral camera, a data acquisition module and a sample transfer table. SWIR hyperspectral images were obtained for melamine-milk samples with different melamine concentrations, pure melamine and pure milk powder. Analysis of variance and the partial least squares regression method over the 1000-2500 nm wavelength region were used to develop an optimal model for detection. The results showed that a melamine concentration as low as 50 ppm in melamine-milk powder samples could be detected. Thus, the MCT-based SWIR hyperspectral imaging system has the potential for quantitative and qualitative detection of adulterants in powder samples.

The protective role of bee honey against the toxic effect of melamine in the male rat kidney.

PubMed

Al-Seeni, Madeha N; El Rabey, Haddad A; Al-Solamy, Suad M

2015-06-01

This study aimed to test the protective role of natural bee honey against melamine toxicity in the kidney of male albino rats. The dietary supplementation of melamine at a dose of 20,000 ppm for 28 days induced renal dysfunction, as reflected by a significant increase in kidney function parameters (urea, creatinine, and uric acid) and an increase in potassium levels. In addition, a decrease in catalase and glutathione-S-transferase and an increase in lipid peroxide in the kidney tissue homogenate were also observed. Histological changes in the melamine-treated group revealed hyperplasia and damage in kidney cells and the accumulation of melamine crystals in kidney tissues. Honey treatment for 28 days in rats concurrently administered melamine at a dose of 2.5 g/kg body weight for 28 days improved the kidney function, increased antioxidant enzymes, and decreased lipid peroxide levels. The morphology of the kidney cells of the melamine-fed rats was also improved as a result of honey treatment. In conclusion, this study revealed that natural bee honey protects the kidney against the adverse effects induced by melamine toxicity in male albino rats. © The Author(s) 2014.

Rapid determination of melamine in milk using water-soluble CdTe quantum dots as fluorescence probes.

PubMed

Zhang, Minwei; Ping, Hong; Cao, Xianyi; Li, Hongkun; Guan, Fengrui; Sun, Chunyan; Liu, Jingbo

2012-01-01

Water-soluble CdTe quantum dots of different sizes capped with thioglycolic acid (TGA-CdTe QDs) were synthesised via a microwave-assisted method. It was found that melamine could quench the fluorescence emission of TGA-CdTe QDs in aqueous solution. Based on this, a novel method for the determination of melamine has been developed. Under optimum conditions, the fluorescence intensity of TGA-CdTe QDs versus melamine concentrations gave a linear response according to the Stern-Volmer equation. The proposed method has been successfully used to detect melamine in liquid milk with a detection limit of 0.04 mg L⁻¹, and the whole process including sample pre-treatment could be accomplished within 30 min. The obvious merits provided by this method, such as simplicity, rapidity, low cost and high sensitivity would make it promising for on-site screening of melamine adulterant in milk products. The possible mechanism involved in the interaction of melamine with TGA-CdTe QDs is discussed.

Melamine nephrotoxicity: an emerging epidemic in an era of globalization.

PubMed

Bhalla, Vivek; Grimm, Paul C; Chertow, Glenn M; Pao, Alan C

2009-04-01

Recent outbreaks of nephrolithiasis and acute kidney injury among children in China have been linked to ingestion of milk-based infant formula contaminated with melamine. These cases provide evidence in humans for the nephrotoxicity of melamine, which previously had been described only in animals. The consequences of this outbreak are already severe and will likely continue to worsen. Herein we summarize the global impact of the melamine milk contamination, the reemergence of melamine-tainted animal feed, and potential mechanisms of melamine nephrotoxicity. Large-scale epidemiologic studies are necessary to further characterize this disease and to assess its potential long-term sequelae. This epidemic of environmental kidney disease highlights the morbidity associated with adulterated food products available in today's global marketplace and reminds us of the unique vulnerability of the kidney to environmental insults. Melamine is the latest in a growing list of diverse potentially toxic compounds about which nephrologists and other health-care providers responsible for the diagnosis and management of kidney disease must now be aware.

Can melamine-based wood primers help in understanding bonded wood durability?

Treesearch

Charles R. Frihart; Jermal G. Chandler

2006-01-01

Melamine–formaldehyde adhesives form wood bonds with exterior durability, and the melamine is more easily studied because of its significant nitrogen content (compared with the lack of nitrogen in wood components). In addition, some melamine–formaldehyde chemicals reduce wood swelling [6], enter into wood cell walls [7], and strengthen them [8]. This information led to...

Melamine detection in infant formula powder using near- and mid-infrared spectroscopy.

PubMed

Mauer, Lisa J; Chernyshova, Alona A; Hiatt, Ashley; Deering, Amanda; Davis, Reeta

2009-05-27

Near- and mid-infrared spectroscopy methods (NIR, FTIR-ATR, FTIR-DRIFT) were evaluated for the detection and quantification of melamine in infant formula powder. Partial least-squares (PLS) models were established for correlating spectral data to melamine concentration: R(2) > 0.99, RMSECV ≤ 0.9, and RPD ≥ 12. Factorization analysis of spectra was able to differentiate unadulterated infant formula powder from samples containing 1 ppm melamine with no misclassifications, a confidence level of 99.99%, and selectivity > 2. These nondestructive methods require little or no sample preparation. The NIR method has an assay time of 1 min, and a 2 min total time to detection. The FTIR methods require up to 5 min for melamine detection. Therefore, NIR and FTIR methods enable rapid detection of 1 ppm melamine in infant formula powder.

Triplex DNA formation-mediated strand displacement reaction for highly sensitive fluorescent detection of melamine.

PubMed

Liu, Xiaojuan; Xu, Ningning; Gai, Panpan; Li, Feng

2018-08-01

Since melamine is a strong hazard to human health, the development of new methods for highly sensitive detection of melamine is highly desirable. Herein, a novel fluorescent biosensing strategy was designed for sensitive and selective melamine assay based on the recognition ability of abasic (AP) site in triplex towards melamine and signal amplification by Mg 2+ -dependent DNAzyme. In this strategy, the melamine-induced formation of triplex DNA was employed to trigger the strand displacement reaction (SDR). The SDR process converted the specific target recognition into the release and activation of Mg 2+ -dependent DNAzyme, which could catalyze the cleavage of fluorophore/quencher labeled DNA substrate (FQ), resulting in a significantly increased fluorescent signal. Under the optimal conditions, the fluorescent signal has a linear relationship with the logarithm of the melamine concentration in a wide range of 0.005-50 μM. The detection limit was estimated to be 0.9 nM (0.1ppb), which is sufficiently sensitive for practical application. Furthermore, this strategy exhibits high selectivity against other potential interfering substances, and the practical application of this strategy for milk samples reveals that the proposed strategy works well for melamine assay in real samples. Therefore, this strategy presents a new method for the sensitive melamine assay and holds great promise for sensing applications in the environment and the food safety field. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of water uptake on melamine renal stone formation in mice.

PubMed

Peng, Jiao; Li, Daxu; Chan, Yee Kwan; Chen, Yan; Lamb, Jonathan R; Tam, Paul K H; El-Nezami, Hani

2012-06-01

Melamine-tainted food can induce kidney stones both in humans and animals and in domestic animals, severe cases caused acute kidney failure and death. Although increasing water intake can ameliorate kidney stone formation, its effect on melamine (Mel)-induced kidney stones has not been studied. We have analysed the effect of restricted ingestion of drinking water on melamine stone formation in mice. They were given melamine and cyanuric acid orally and received drinking water either freely or for a restricted time. Kidney stone formation and renal function were monitored. Mice receiving drinking water for a restricted 10-h period initially lost body weight, which returned to normal within 2 days. No other abnormalities were observed. Ingestion of melamine alone failed to induce kidney stones even under conditions of restricted drinking water. In mice treated with melamine together with cyanuric acid for 3 days, no renal stones were formed when the supply of drinking was normal. However, when drinking water was limited, stone formation was observed and accompanied by high levels of serum urea and creatinine. An increase in urine haemoglobin and glucose levels was also found. The administration resulted in up-regulated tissue osteopontin, kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin messenger RNA expression and macrophage infiltration. Our results indicate the importance of water intake in the formation of melamine-induced renal stone formation in the mouse and provide new information on the mechanisms of melamine stone formation.

Finger-Jointed Wood Products.

DTIC Science & Technology

1981-04-01

these melamines do not have the same Urea resins are generally marketed adhesives does not always develop resistance to weathering as do in liquid form...OF durable, colorless glueline is required. been developed for use in RF curing. FINGER JOINTS MelamineUrea Resins IN STRUCTURAL Melamine - urea resins ...finger duced either by dry blending urea and moplastic, softening if temperature is joints, strength is expressed as a melamine resins or by blending

Release rate of diazinon from microcapsule based on melamine formaldehyde

NASA Astrophysics Data System (ADS)

Noviana Utami C., S.; Rochmadi

2018-04-01

The microcapsule containing diazinon as the core material and melamine formaldehyde as the membrane material have been synthesized by in situ polymerization method. The microcapsule membrane in this research is melamine formaldehyde (MF). This research aims to study the effect of pH and temperature on the release rate of diazinon from microcapsule based on melamine formaldehyde in aqueous medium. The results showed that 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.

Melamine-formaldehyde aerogels

DOEpatents

Pekala, Richard W.

1992-01-01

Organic aerogels that are transparent and essentially colorless are prepa from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porsity, ultrafine cell/pore sizes, and optical clarity.

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Melamine-formaldehyde aerogels

DOEpatents

Pekala, R.W.

1992-01-14

Organic aerogels that are transparent and essentially colorless are prepared from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porosity, ultrafine cell/pore sizes, and optical clarity. 3 figs.

Quantitative detection of melamine based on terahertz time-domain spectroscopy

NASA Astrophysics Data System (ADS)

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.

[Pathological changes in rat model of urinary calculus induced by melamine].

PubMed

Shen, Ying; Sun, Ning; Wang, Guan-nan; He, Le-jian; Jia, Li-qun; Wang, Yu; Xiao, Hong-zhan; Lü, Rui-fen

2011-09-01

To investigate melamine-induced pathological changes in the kidney. Wistar rats were fed with a diet containing 0, 1% and 2% melamine for 15 weeks. After melamine feeding was stopped, various outcome measures were observed for 4 weeks. Rats fed with melamine showed reduced caloric intake, slower weight gain and impaired renal function. The blood urea nitrogen of group A and B [(13.23 ± 5.10) mmol/L and (18.30 ± 5.90) mmol/L, respectively] and serum creatinine levels of group B [(19.90 ± 2.90) mmol/L] were higher than that of group C [(8.23 ± 2.30) mmol/L and (10.04 ± 1.73) mmol/L](P < 0.01, respectively). Additionally, the kidney coefficients of group A and B were higher than that of group C (P < 0.01, respectively). Crystals, tubular ectasia and interstitial inflammation and fibrosis were found in the kidneys of melamine fed rats. Four weeks after discontinuation of feeding with melamine-contained diet, the caloric intake and weight of the rats increased, the coefficients of the kidney decreased, and the blood urea nitrogen of group A and B [(17.96 ± 2.04) mmol/L and (19.20 ± 3.36) mmol/L, respectively] and serum creatinine levels of group B [(24.20 ± 5.28) mmol/L], which became worse than 4 weeks before (P < 0.01;P < 0.05, respectively), and were still higher than that of group C [(8.30 ± 1.79) mmol/L and (9.87 ± 2.71) mmol/L, P < 0.01, respectively]. Crystals remained inside the kidney, changes in the renal interstitium did not improve. (1) Melamine-induced urinary calculus rat model can be established by feeding 3-week old male Wistar rats with a diet containing 2% melamine for 15 weeks. The main constituent of the urinary calculus was melamine (> 90%), with a little uric acid and traces of cyanuric acid. (2) Melamine damaged the renal function, formed renal crystals, and led to the pathological changes of kidneys. All the influences seemed to be dose-depended and was related with the obstruction of the crystals or calculus in the kidney. (3) The renal function and the pathological changes did not improve 4 weeks after discontinuation of feeding with melamine-contained diet.

Environmentally Safe and Effective Processes for Paint Removal

DTIC Science & Technology

1995-04-01

Urea Formaldehyde 3.5 1.5 Type III Melamine Formaldehyde 4.0 1.5 Type IV Phenol Formaldehyde 3.5 1.5...Polyester 3.0 34 - 42 1.04 - 1.46 Type II Urea Formaldehyde 3.5 54 - 62 1.47- 1.54 Type III Melamine Formaldehyde 4.0 64- 72 1.47- 1.52 Type IV Phenol... Melamine Formaldehyde electronics industry and to remove coatings from fibreglass and composite materials. Melamine formaldehyde resin is produced

Migration of melamine and formaldehyde from tableware made of melamine resin.

PubMed

Ishiwata, H; Inoue, T; Tanimura, A

1986-01-01

Migration of melamine and formaldehyde into food-simulating solvents from cups made of melamine resin was studied under various conditions. Little migration of melamine was observed in any unused cups kept at 60 degrees C for 30 min, room temperature (26 degrees C) for 1 h or cooled at -20 degrees C for several days. Migration of both compounds was strongly affected by heating and acidity. The highest migration of melamine into 4% acetic acid used as a food-simulating solvent was 42.9 +/- 7.2 ppm when the migration test was repeated seven times at 95 degrees C for 30 min. In this time, the migration of formaldehyde was 14.2 +/- 0.6 ppm into the solvent. The molecular ratio of the migration amount of formaldehyde to melamine decreased according to the formula Y = 9.15X-0.813 over seven repetitions of the test, and was maintained at about 1.6 between the 10th and 20th repetitions. The inner surface of the cups became tarnished during the repetition of the test and their roughness increased from 1 micron before the test to 2.5-5 microns after 20 repetitions of the test. Migration of melamine from the cups being used at a cafeteria was 0.4 +/- 0.5 ppm, but that of formaldehyde was undetectable when the cups were kept at 60 degrees C for 30 min with 4% acetic acid.

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

NASA Astrophysics Data System (ADS)

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.

Gender and urinary pH affect melamine-associated kidney stone formation risk

PubMed Central

Lu, Xiuli; Wang, Jing; Cao, Xiangyu; Li, Mingxin; Xiao, Chunling; Yasui, Takahiro; Gao, Bing

2011-01-01

Objectives: Melamine was known as a new risk for kidney stone due to recent incidences of milk powder contamination in China. Here, we performed a retrospective study to investigate whether age, gender, and urinary pH affect melamine-associated kidney stone risk. Materials and Methods: A retrospective review was performed of 217 children aged less than 3 years old. All children had a history of being fed with Sanlu milk powder contaminated by melamine, and underwent a clinical screening on kidney stone in Shenyang from November 2008 to February 2009. A comparison with the Chi-square was conducted between 83 cases and 125 normal subjects. The difference between children's gender, age, and urinary pH was evaluated. Results: A total of 208 subjects, 136 boys and 72 girls, were included in the study. Significant association was observed between melamine-associated kidney stone risk and gender [odds ratio (OR), 2.03; 95% confidence interval (CI), 1.11-3.74; P=0.02] and urinary pH (OR, 1.78; 95% CI, 1.01-3.11; P=0.04), respectively. Male children were at about twofold increased melamine-associated kidney stone risk compared with female children. Acidic urine showed about 1.78-fold increased melamine-associated kidney stone risk compared with normal urine. Conclusions: Our investigation results showed an association of gender and urinary pH with melamine-associated kidney stone formation risk. PMID:21747595

Determination of spatial distribution of melamine-cyanuric acid crystals in rat kidney tissue by histology and imaging matrix-assisted laser desorption/ionization quadrupole time-of-flight mass spectrometry.

PubMed

Kim, Chae-Wook; Yun, Jun-Won; Bae, Il-Hong; Lee, Joon-Seok; Kang, Hyun-Jin; Joo, Kyung-Mi; Jeong, Hye-Jin; Chung, Jin-Ho; Park, Young-Ho; Lim, Kyung-Min

2010-01-01

After the outbreak of acute renal failure associated with melamine-contaminated pet food, many attempts have been made to uncover the mechanism underlying the renal toxicity caused by melamine and melamine-related compounds. Using rat models, we investigated the renal crystal formation following the ingestion of a melamine-cyanuric acid mixture (M+CA, 1:1) to gain insight into the M+CA-induced renal toxicity. M+CA did not induce toxicity in precision-cut kidney slices, suggesting that M+CA does not have a direct nephrotoxicity. On the contrary, oral administration of M+CA for 3 days induced nephrotoxicity as determined by increased serum blood urea nitrogen and creatinine, reduced creatinine clearance, and enlarged kidneys in the animals treated with 50 mg/kg M+CA (melamine, 25 mg/kg, and cyanuric acid, 25 mg/kg; 2 of 10 animals) and 100 mg/kg M+CA (9 of 9 animals). While urine crystals were found in all animals treated with M+CA (25-100 mg/kg), histological examination revealed that renal crystals could be observed only in the kidneys of animals showing signs of nephrotoxicity. Remarkably, at 50 mg/kg M+CA, crystals were observed mainly in the medulla region of the kidney, while at 100 mg/kg, crystals were disseminated throughout the cortex and medulla regions. To further investigate the crystal formation by M+CA, matrix-assisted laser desorption/ionization quadrupole time-of-flight (MALDI-Q-TOF) imaging mass spectrometry detecting melamine distribution through monitoring the product ion (m/z 85, M + H) from melamine (m/z 127, M + H) was developed to directly obtain the image of melamine distribution in the kidney. The distribution image of melamine in kidney tissue confirmed that dense points of melamine were located only in the medulla region at 50 mg/kg M+CA, while at 100 mg/kg, they were disseminated widely from the cortex to medulla. These results demonstrated that M+CA ingestion could lead to crystal formation in kidney tubules along the osmotic gradient and that renal crystal formation is closely linked with M+CA-induced nephrotoxicity.

Preparation of [13C3]-melamine and [13C3]-cyanuric acid and their application to the analysis of melamine and cyanuric acid in meat and pet food using liquid chromatography-tandem mass spectrometry.

PubMed

Varelis, P; Jeskelis, R

2008-10-01

For the determination of melamine and cyanuric acid the labelled internal standards [(13)C(3)]-melamine and [(13)C(3)]-cyanuric acid were synthesized using the common substrate [(13)C(3)]-cyanuric chloride by reaction with ammonia and acidified water, respectively. Standards with excellent isotopic and chemical purities were obtained in acceptable yields. These compounds were used to develop an isotope dilution liquid chromatography/mass spectrometry (LC/MS) method to determine melamine and cyanuric acid in catfish, pork, chicken, and pet food. The method involved extraction into aqueous methanol, liquid-liquid extraction and ion exchange solid phase clean-up, with normal phase high-performance liquid chromatography (HPLC) in the so-called hydrophilic interaction mode. The method had a limit of detection (LOD) of 10 microg kg(-1) for both melamine and cyanuric acid in the four foods with a percentage coefficient of variation (CV) of less than 10%. The recovery of the method at this level was in the range of 87-110% and 96-110% for melamine and cyanuric acid, respectively.

Visual and light scattering spectrometric method for the detection of melamine using uracil 5‧-triphosphate sodium modified gold nanoparticles

NASA Astrophysics Data System (ADS)

Liang, Lijiao; Zhen, Shujun; Huang, Chengzhi

2017-02-01

A highly selective method was presented for colorimetric determination of melamine using uracil 5‧-triphosphate sodium modified gold nanoparticles (UTP-Au NPs) in this paper. Specific hydrogen-bonding interaction between uracil base (U) and melamine resulted in the aggregation of AuNPs, displaying variations of localized surface plasmon resonance (LSPR) features such as color change from red to blue and enhanced localized surface plasmon resonance light scattering (LSPR-LS) signals. Accordingly, the concentration of melamine could be quantified based on naked eye or a spectrometric method. This method was simple, inexpensive, environmental friendly and highly selective, which has been successfully used for the detection of melamine in pretreated liquid milk products with high recoveries.

Label-free turn-on fluorescent detection of melamine based on the anti-quenching ability of Hg 2+ to gold nanoclusters.

PubMed

Dai, Haichao; Shi, Yan; Wang, Yilin; Sun, Yujing; Hu, Jingting; Ni, Pengjuan; Li, Zhuang

2014-03-15

In this work, we proposed a facile, environmentally friendly and cost-effective assay for melamine with BSA-stabilized gold nanoclusters (AuNCs) as a fluorescence reader. Melamine, which has a multi-nitrogen heterocyclic ring, is prone to coordinate with Hg(2+). This property causes the anti-quenching ability of Hg(2+) to AuNCs through decreasing the metallophilic interaction between Hg(2+) and Au(+). By this method, detection limit down to 0.15 µM is obtained, which is approximately 130 times lower than that of the US food and Drug Administration estimated melamine safety limit of 20 µM. Furthermore, several real samples spiked with melamine, including raw milk and milk powder, are analyzed using the sensing system with excellent recoveries. This gold-nanocluster-based fluorescent method could find applications in highly sensitive detection of melamine in real samples. © 2013 Elsevier B.V. All rights reserved.

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

PubMed

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.

Characterization of newfound natural luminescent properties of melamine, and development and validation of a method of high performance liquid chromatography with fluorescence detection for its determination in kitchen plastic ware.

PubMed

Finete, Virginia de Lourdes Mendes; Gouvêa, Marcos Martins; Marques, Flávia Ferreira de Carvalho; Netto, Annibal Duarte Pereira

2014-06-01

Experimental studies of the natural photoluminescence of melamine in aqueous solutions showed that its fluorescence intensity (at 250/365 nm) was appropriated for analytical purposes. The exploitation of such melamine property provided the basis of development of a new, simple, precise and accurate method based on high performance liquid chromatography with fluorescence detection (HPLC-Fluo) to determine melamine in kitchen plastic ware following aqueous extraction using a microwave oven. Optimization of analytical parameters such as solvent composition, pH and extraction conditions led to limits of detection and quantification of melamine of 0.0081 and 0.027 μg mL(-1), respectively, with a linear range up to 10 μg mL(-1). Sample extracts fortified with melamine at three concentration levels produced an average recovery of 98±6%, which was in agreement with the results achieved with a reference HPLC-UV method. Different samples of kitchen plastic ware analyzed by the developed and optimized method showed melamine concentrations in the aqueous extract up to 17 µg mL(-1), which corresponded to 86.0 mg kg(-1) in these utensils. The results obtained indicate that the use of kitchen plastic ware made of melamine can contaminate food with this compound after heating in a microwave oven. Copyright © 2014. Published by Elsevier B.V.

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

NASA Astrophysics Data System (ADS)

Li, Jianfang; Huang, Pengcheng; Wu, Fangying

2016-06-01

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 (A650nm/A520nm) of p-chlorobenzenesulfonic acid-AuNPs. Under optimized conditions, the system exhibited a linear response to melamine in the range of 6.0 × 10-7-1.5 × 10-6 mol L-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 Ca2+, Zn2+, 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.

Sensitivity and specificity enhanced enzyme-linked immunosorbent assay by rational hapten modification and heterogeneous antibody/coating antigen combinations for the detection of melamine in milk, milk powder and feed samples.

PubMed

Cao, Biyun; Yang, Hong; Song, Juan; Chang, Huafang; Li, Shuqun; Deng, Anping

2013-11-15

The adulteration of food products with melamine has led to an urgent requirement for sensitive, specific, rapid and reliable quantitative/screening methods. To enhance the sensitivity and specificity of the enzyme-linked immunosorbent assay (ELISA) for the detection of melamine in milk, milk powder and feed samples, rational hapten modification and heterogeneous antibody/coating antigen combinations were adopted. Three melamine derivatives with different length of carboxylic spacer at the end were synthesized and linked to carrier proteins for the production of immunogens and coating antigens. Monoclonal antibody against melamine was produced by hybridoma technology. Under optimal experimental conditions, the standard curves of the ELISAs for melamine were constructed in range of 0.1-100 ng mL(-1). The sensitivity was 10-300 times enhanced compared to those in the published literatures. The cross-reactivity values of the ELISAs also demonstrated the assays exhibited high specificity. Five samples were spiked with melamine at different concentrations and detected by the ELISA. The recovery rates of 72.8-123.0% and intra-assay coefficients of variation of 0.8-18.9% (n=3) were obtained. The ELISA for milk sample was confirmed by high-performance liquid chromatography with a high correlation coefficient of 0.9902 (n=6). The proposed ELISA was proven to be a feasible quantitative/screening method for melamine analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

Formaldehyde - An Assessment of its Health Effects.

DTIC Science & Technology

1980-03-01

impregnated with melamine - formaldehyde resin ...1961). Airborne formaldehyde concentrations released from paper treated with urea - formaldehyde or melamine - formaldehyde resin were found to be 0.9-1.6...as preservatives, and in the preparation of vaccines. It is widely used in the manufacture of phenolic, urea , and melamine resins . These materials

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

NASA Astrophysics Data System (ADS)

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.

Assessment of chronic renal injury from melamine-associated pediatric urolithiasis: an eighteen-month prospective cohort study.

PubMed

Gao, Jian; Wang, Fei; Kuang, Xinyu; Chen, Rong; Rao, Jia; Wang, Bin; Li, Wenyan; Liu, Haimei; Shen, Qian; Wang, Xiang; Xu, Hong

2016-01-01

The illegal use of melamine in powdered baby formula resulted in a widespread outbreak of melamine-associated pediatric urolithiasis and kidney damage in China in 2008. We conducted this study because more needs to be known about the long-term effects of melamine-associated urolithiasis and kidney damage. To determine the prognosis and long-term implications of chronic kidney damage in children with urolithiasis resulting from melamine consumption. Prospective cohort study. Children's Hospital of Fudan University. Children six years of age or older with a history of having consumed melamine-contaminated milk powder were voluntarily screened. We measured urinary microprotein profiles [microalbumin (ALBU), immunoglobulin G (IgG), and n-acetyl-ß-d-glucosidase (NAG)] and creatinine (CR) results at 6 and 18 months in children with melamine-associated urolithiasis. This study was conducted from September 17 to October 15, 2008. Changes in urinary microprotein profiles. Of 8335 children screened, 102 children (1.22%) were diagnosed with melamine-associated urolithiasis. Follow-up rates at 6 and 18 months were 91.4% (96/105) and 89.2% (91/102), respectively. Eighteen months later, 90.3% patients had spontaneously passed a stone. The incidence rates of proteinuria and microscopic hematuria at 6 months were significantly higher than at 18 months (P=.029 and P=.017, respectively). The proportion of patients with abnormal ALBU/CR, IgG/CR and NAG/CR at 6 months (27.6%, 17.1% and 21.1%, respectively) was significantly higher than at 18 months (6.4%, 5.1% and 12.8%, respectively). The high concentration of melamine consumed was the primary factor correlated with the high microprotein levels. Approximately 90% melamine-associated urolithiasis cases can be resolved within 18 months by non-surgical therapy. The long-term presence of stones associated with a previous exposure to melanine can cause chronic kidney glomerular and tubular injuries. Passing these stones as soon as possible can reduce kidney injury and accelerate recovery. We could not control for possible selection bias due to more visits to our hospital or visits to our hospital after diagnosis at other hospitals, which might have increased the rate of diagnosis.

Raman-spectroscopy-based chemical contaminant detection in milk powder

NASA Astrophysics Data System (ADS)

Dhakal, Sagar; Chao, Kuanglin; Qin, Jianwei; Kim, Moon S.

2015-05-01

Addition of edible and inedible chemical contaminants in food powders for purposes of economic benefit has become a recurring trend. In recent years, severe health issues have been reported due to consumption of food powders contaminated with chemical substances. This study examines the effect of spatial resolution used during spectral collection to select the optimal spatial resolution for detecting melamine in milk powder. Sample depth of 2mm, laser intensity of 200mw, and exposure time of 0.1s were previously determined as optimal experimental parameters for Raman imaging. Spatial resolution of 0.25mm was determined as the optimal resolution for acquiring spectral signal of melamine particles from a milk-melamine mixture sample. Using the optimal resolution of 0.25mm, sample depth of 2mm and laser intensity of 200mw obtained from previous study, spectral signal from 5 different concentration of milk-melamine mixture (1%, 0.5%, 0.1%, 0.05%, and 0.025%) were acquired to study the relationship between number of detected melamine pixels and corresponding sample concentration. The result shows that melamine concentration has a linear relation with detected number of melamine pixels with correlation coefficient of 0.99. It can be concluded that the quantitative analysis of powder mixture is dependent on many factors including physical characteristics of mixture, experimental parameters, and sample depth. The results obtained in this study are promising. We plan to apply the result obtained from this study to develop quantitative detection model for rapid screening of melamine in milk powder. This methodology can also be used for detection of other chemical contaminants in milk powders.

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

Treesearch

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...

Rapid, On-Site, Ultrasensitive Melamine Quantitation Method for Protein Beverages Using Time-Resolved Fluorescence Detection Paper.

PubMed

Li, Guanghua; Wang, Du; Zhou, Aijun; Sun, Yimin; Zhang, Qi; Poapolathep, Amnart; Zhang, Li; Fan, Zhiyong; Zhang, Zhaowei; Li, Peiwu

2018-06-06

To ensure protein beverage safety and prevent illegal melamine use to artificially increase protein content, a rapid, on-site, ultrasensitive detection method for melamine must be developed because melamine is detrimental to human health. Herein, an ultrasensitive time-resolved fluorescence detection paper (TFDP) was developed to detect melamine in protein beverages within 15 min using a one-step sample preparation. The lower limits of detection were 0.89, 0.94, and 1.05 ng/mL, and the linear ranges were 2.67-150, 2.82-150, and 3.15-150 ng/mL (R 2 > 0.982) for peanut, walnut, and coconut beverages, respectively. The recovery rates were 85.86-110.60% with a coefficient of variation <7.80% in the spiking experiment. A high specificity was observed in the interferent experiment. When detecting real protein beverage samples, the TFDP and ultraperformance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) results were consistent. This method is a promising alternative for rapid, on-site detection of melamine in beverages.

Synthesis and Thermal Degradation Studies of Melamine Formaldehyde Resins

PubMed Central

Ullah, Sami; Bustam, M. A.; Nadeem, M.; 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. PMID:25436237

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

PubMed Central

2016-01-01

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. PMID:27525154

The natural outcome of melamine-induced bladder stones with bladder epithelial hyperplasia after the withdrawal of melamine in mice.

PubMed

Ren, Shu-Ting; Xu, Chang-Fu; Du, Yun-Xia; Gao, Xiao-Li; Sun, Ying; Jiang, Yi-Na

2012-07-01

The natural outcome of melamine-induced bladder stones (cystoliths) with bladder epithelial hyperplasia (BEH) after melamine withdrawn is unclear. Using an ideal dual-model system, three experiments were conducted in BALB/c mice. Each experiment included a control, model 1 and model 2 groups. The mice were fed a regular diet in controls or a 9373 ppm melamine diet in models, and the first day was designated as dosing day 1. The melamine diet was then replaced by the regular diet in the model 2 groups, and the first day was designated as post-dosing day 1. On dosing days 12, 35 and 49, the incidence of cystoliths and diffusely active BEH was 8/8 in the mice of three model 1 groups. On post-dosing days 1, 4 and 8, in the mice of three model 2 groups, the incidence of cystoliths was 2/8, 0/8 and 1/8, respectively, and the progressive regression of BEH was observed. In conclusion, both the stones and BEH have the natural property of rapid development and rapid regression, and melamine withdrawn plays a key role in the stone dissolution-discharge necessary for BEH regression. BEH may be reversible after the discharge of the stones. The conventionally conservative therapy is thus reasonable. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

PubMed

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.

Melamine-modified urea formaldehyde resin for bonding particleboards

Treesearch

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...

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

Treesearch

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...

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

Treesearch

Tomita Bunchiro; Chung-Yun Hse

1995-01-01

The 13C-NMR (carbon 13 nuclear magnetic resonance) spectra of urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins synthesized under various conditions were taken with a frequency of 75 MHz. The main purpose was to investigate whether or not the occurrences of cocondensation...

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

Treesearch

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...

Analysis of cocondensation of melamine and urea through formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

Treesearch

Bunichiro Tomita; Chung-Yun Hse

1995-01-01

The 13C-NMR (carbon 13 nuclear magnetic resonance) spectra of urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins synthesized under various conditions were taken with a frequency of 75 MHz. The main purpose was to investigate whether or not the occurrences of cocondensation...

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.

PubMed

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.

Effect of Coversheet Materials on the Acoustic Performance of Melamine Foam

NASA Technical Reports Server (NTRS)

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.

Interfacially enhancement of PBO/epoxy composites by grafting MWCNTs onto PBO surface through melamine as molecular bridge

NASA Astrophysics Data System (ADS)

Lv, Junwei; Wang, Bin; Ma, Qi; Wang, Wenjing; Xiang, Dong; Li, Mengyao; Zeng, Lan; Li, Hui; Li, Yuntao; Zhao, Chunxia

2018-06-01

Melamine and multi-walled carbon nanotubes (MWCNTs) were grafted onto Poly-p-phenylene benzobisoxazole (PBO) fiber surface effectively via layer-by-layer method. Both of them have been chemically bonded as fourier transform infrared spectroscopy (FTIR) confirmed. Grafting melamine overcame the inertness of PBO surface. Ammoniation was processed on PBO surface through grafting melamine so that the MWCNTs could be grafted onto PBO surface. Scanning electron microscopy (SEM) images indicated that melamine used as molecular bridge could increase MWCNTs’ quantity on PBO surface. X-ray photoelectron spectroscopy (XPS) results revealed the variation of chemical composition of PBO surface. Test of interfacial shear strength (IFSS) and tensile strength indicated the great mechanical properties of modified PBO fibers when combining with epoxy resin. Furthermore, whole reaction was processed under a simple condition. Results in this research also promised a potential method to modify PBO surface.

Defense Scrap Yard Handbook

DTIC Science & Technology

1985-06-01

34thermosetting" is an adjective position and the basic resin used. The major class- applied to plastics (such as melamine , phenoliL, es are:a. Acrylics...to heat or flame e. Melamine resins : melamine formalde- test plastic materials for identification purposes. hyde. They must therefore work closely...plastics, together with helpful information as to 1. Polystyrenes. their composition , characteristics and typical ap- m. Polyurethane resins (isocyanate

Method for producing refractory nitrides

DOEpatents

Quinby, Thomas C.

1989-01-24

A process for making fine, uniform metal nitride powders that can be hot pressed or sintered. A metal salt is placed in a solvent with Melamine and warmed until a metal-Melamine compound forms. The solution is cooled and the metal-Melamine precipitate is calcined at a temperature below 700.degree. C. to form the metal nitrides and to avoid formation of the metal oxide.

Non-destructive prediction of low levels of melamine particles in milk powder using hyperspectral reflectance imaging and partial least square regression model

USDA-ARS?s Scientific Manuscript database

Melamine has been used in industrial manufacturing of numerous forms of plastics, fertilizer, adhesives and laminates. In 2008, dairy products tainted with melamine have been reported to be responsible for kidney stones and renal failure among infants and children in China. Some dairy farmers and ma...

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

NASA Astrophysics Data System (ADS)

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.

Rapid and selective screening of melamine in bovine milk using molecularly imprinted matrix solid-phase dispersion coupled with liquid chromatography-ultraviolet detection.

PubMed

Yan, Hongyuan; Cheng, Xiaoling; Sun, Ning; Cai, Tianyu; Wu, Ruijun; Han, Kun

2012-11-01

A simple, convenient and high selective molecularly imprinted matrix solid-phase dispersion (MI-MSPD) using water-compatible cyromazine-imprinted polymer as adsorbent was proposed for the rapid screening of melamine from bovine milk coupled with liquid chromatography-ultraviolet detection. The molecularly imprinted polymers (MIPs) synthesized by cyromazine as dummy template and reformative methanol-water system as reaction medium showed higher affinity and selectivity to melamine, and so they were applied as the specific dispersant of MSPD to extraction of melamine and simultaneously eliminate the effect of template leakage on quantitative analysis. Under the optimized conditions, good linearity was obtained in a range of 0.24-60.0μgg(-1) with the correlation coefficient of 0.9994. The recoveries of melamine at three spiked levels were ranged from 86.0 to 96.2% with the relative standard deviation (RSD)≤4.0%. This proposed MI-MSPD method combined the advantages of MSPD and MIPs, and could be used as an alternative tool for analyzing the residues of melamine in complex milk samples. Copyright © 2012 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dante, Roberto C., E-mail: rcdante@yahoo.com; Sánchez-Arévalo, Francisco M.; Chamorro-Posada, Pedro

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, themore » 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.« less

Melamine contamination in nutritional supplements--Is it an alarm bell for the general consumer, athletes, and 'Weekend Warriors'?

PubMed

Gabriels, Gary; Lambert, Mike; Smith, Pete; Wiesner, Lubbe; Hiss, Donavon

2015-07-17

Nutritional supplements are used or experimented with by consumers, notably these are; competitive and recreational athletes of all ages, and 'weekend warriors'. As a consequence the supplement industry has grown to meet the increasing demand. A Global Industry Analysts Inc. report indicates that the herbal supplement market has not declined during the worldwide recession, but in fact exhibited steady growth over the period 2008 to 2009. It is anticipated that the market will reach US$93.15 billion by the year 2015. These supplements may contain adulterated substances that may potentially have harmful short - and long-term health consequences to the consumer. "Scrap Melamine" is such an example, which has been implicated in the kidney failure and death of several cats, dogs and pigs. In China in 2008, reports described very severe health effects in infants and young children. At the time over 294,000 infants were screened and diagnosed with urinary tract stones and sand-like calculi associated with melamine in milk products, of which 50,000 infants were hospitalised, and at least six associated deaths, recorded. The extent that melamine contamination occurs in nutritional supplements is not known. Therefore, the aim of this study was to determine whether commercially available nutritional and traditional supplement products contain melamine, even though they are not declared by the manufacturer on the product label. A total of 138 nutritional supplements products were obtained from (i) direct purchases from shops, pharmacies and outlets, (ii) directly from consumers, and (iii) from suppliers, manufacturers and distributors. The products were laboratory analysed for melamine, using Tandem Liquid Chromatography Mass Spectrometry. Forty-seven % of all the products (n = 138) tested positive for melamine. Eight-two % of the South African produced products (n = 27) tested positive and 58 % of the products imported into South Africa (n = 50) tested positive. The median concentration estimate for melamine in the products tested were, 6.0 μg/g for the 138 supplements tested, 8.9 μg/g for South African produced products, and 6.9 μg/g for products imported into South Africa. The melamine (undeclared on product label) levels detected in the nutritional supplements products investigated were within the Tolerable Daily intake (TDI) limit guidelines of 200 μg/g as set by WHO and others. Melamine over exposure within the context of the nutritional supplements consumption in the products investigated should not be of concern to the consumer provided the recommended guidelines of daily product use are adhered to. Further investigation is warranted to determine, (i) the link of melamine as (part) substitute for the perceived total declared protein content on the product label, (ii) cyanuric and uric acid presence in the supplement products that could form chemical-complex formation with melamine and/or analogues that could cause adverse health effects.

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

Treesearch

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...

Modeling of Compaction Wave Behavior in Confined Granular Energetic Material

DTIC Science & Technology

1990-08-01

Compacted 65% TMD Aggregate Melamine Compaction Wave Microwave DIAGNOSTICS: Interferometry (a) Microwave Interferometry (b) 3 Wall-Mounted Pressure...involved 65% TMD melamine but was run very recently (Dec 1989) The value of compaction wave speed (from the microwave data) just after impact is...47 B. Simulation of PDC-M34 / 65% TMD Melamine (Inert Material) ........ 54 C. Influence of Energy Release / PDC Experiment

Detection of melamine in milk powders using Near-Infrared Hyperspectral imaging combined with regression coefficient of partial least square regression model

USDA-ARS?s Scientific Manuscript database

Illegal use of nitrogen-rich melamine (C3H6N6) to boost perceived protein content of food products such as milk, infant formula, frozen yogurt, pet food, biscuits, and coffee drinks has caused serious food safety problems. Conventional methods to detect melamine in foods, such as Enzyme-linked immun...

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

PubMed

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.

Acoustic Test Characterization of Melamine Foam for Usage in NASA's Payload Fairing Acoustic Attenuation Systems

NASA Technical Reports Server (NTRS)

Hughes, William O.; McNelis, Anne M.; McNelis, Mark E.

2014-01-01

The external acoustic liftoff levels predicted for NASA's future heavy lift launch vehicles are expected to be significantly higher than the environment created by today's commercial launch vehicles. This creates a need to develop an improved acoustic attenuation system for future NASA payload fairings. NASA Glenn Research Center initiated an acoustic test series to characterize the acoustic performance of melamine foam, with and without various acoustic enhancements. This testing was denoted as NEMFAT, which stands for NESC Enhanced Melamine Foam Acoustic Test, and is the subject of this paper. Both absorption and transmission loss testing of numerous foam configurations were performed at the Riverbank Acoustical Laboratory in July 2013. The NEMFAT test data provides an initial acoustic characterization and database of melamine foam for NASA. Because of its acoustic performance and lighter mass relative to fiberglass blankets, melamine foam is being strongly considered for use in the acoustic attenuation systems of NASA's future launch vehicles.

NMR-Spectroscopy for Nontargeted Screening and Simultaneous Quantification of Health-Relevant Compounds in Foods: The Example of Melamine

PubMed Central

2009-01-01

The recent melamine crisis in China has pointed out a serious deficiency in current food control systems, namely, they specifically focus on selected known compounds. This targeted approach allowed the presence of melamine in milk products to be overlooked for a considerable time. To avoid such crises in the future, we propose that nontargeted screening methods need to be developed and applied. To this end, NMR has an extraordinary potential that just started to be recognized and exploited. Our research shows that, from the very same set of spectra, 1H NMR at 400 MHz can distinguish between melamine-contaminated and melamine-free infant formulas and can provide quantitative information by integration of individual lines after identification. For contaminated Chinese infant formulas or candy, identical results were obtained when comparing NMR with SPE-LC/MS/MS. NMR was found to be suitable for routine nontargeted and targeted analyses of foods, and its use will significantly increase food safety. PMID:20349917

Fire Safety Aspects of Polymeric Materials. Volume 10. Mines and Bunkers

DTIC Science & Technology

1980-01-01

Formaldehyde and Melamine / Formaldehyde Resins The basic chemistry, properties, and applications of urea / formaldehyde and melamine / formaldehyde resins ... Formaldehyde and Melamine Formaldehyde Rosins 71 4.2.3.3 Unsaturated Polyester Resins 71 4.2.3.4 Epoxy Resins 72 4.2.3.5 Furan Resins 72 4.2.3.6 Amine...aldehyde — most frequently formaldehyde . Urea is often used as a modifying agent. The

Melamine and Cyanuric Acid do not interfere with Bradford and Ninhydrin assays for protein determination.

PubMed

Field, Anjalie; Field, Jeffrey

2010-08-01

In the fall of 2007 pet food contaminated with melamine and cyanuric acid caused kidney stones in thousands of animals. In the summer of 2008, a more serious outbreak of adulterated dairy food caused the deaths of six infants and sickened about 290,000 children in China. In all cases, melamine was likely added to inflate the apparent protein content of the foods. To determine if we could measure protein without interference from melamine and cyanuric acid we tested these compounds in the Bradford and Ninhydrin assays, two common dye-based assays for protein, as well as by ammonia release, the most common assay used in the food industry. Neither compound was detected in the Ninhydrin and Bradford assays at concentrations of >100 μg/ml. The ammonia assay detected melamine but was inconclusive with respect to cyanuric acid. To develop an accurate test for food that would not detect either chemical as a protein, assays were run on cat food and reconstituted milk powder. The Bradford assay readily measured the protein content of each food, and importantly, the addition of melamine or cyanuric acid to reconstituted milk did not affect the readings. The protein concentrations obtained for reconstituted milk powder were as expected, but those for the cat food were 10 to 30-fold lower, due to its low solubility. We conclude that dye-binding assays can be employed to detect protein in food without interference from melamine and cyanuric acid, thus reducing the incentive to use them as additives.

Migration of melamine from can coatings cross-linked with melamine-based resins, into food simulants and foods.

PubMed

Bradley, E L; Castle, L; Day, J S; Leak, J

2011-02-01

Resins based on melamine-formaldehyde and related analogues such as methylolated melamine are used to cross-link coatings used inside food cans and on the metal closures of glass jars. Thirteen commercially coated cans and closures representing 80% of the European market were tested using simulants under realistic industrial heat-processing conditions for canned and jarred foods. The food simulants and the retort conditions used were 3% acetic acid for 1 h at 100 °C and 10% ethanol for 1 h at 130 °C. The highest migration level seen for melamine into simulant was 332 µg kg⁻¹. There was no detectable migration of the melamine analogues cyanuric acid (<1 µg kg⁻¹) or ammelide (<5 µg kg⁻¹) from any sample. Twelve of the thirteen samples released no detectable ammeline (<5 µg kg⁻¹) but the coating giving the highest release of melamine did also release ammeline at 8 µg kg⁻¹ with the higher of the two process temperatures used. Migration experiments into food simulant and foods themselves were then conducted using two experimental coatings made using amino-based cross-linking resins. Coated metal panels were exposed to the food simulant 10% (v/v) aqueous ethanol and to three foodstuffs under a range of time and temperature conditions both in the laboratory and in a commercial food canning facility using proprietary time and temperature conditions. The highest migration into a food was 152 µg kg⁻¹ from the first coating processed for a long time at a moderate sterilisation temperature. The highest migration into simulant was also from this coating at 220 µg kg⁻¹ when processed at 134 °C for 60 min, dropping to 190 µg k⁻¹ when processed at 123 °C for 70 min. Migration from the second coating was quite uniformly two to three times lower under all tests. These migration results were significantly higher than the levels of melamine extractable using 95% ethanol at room temperature. The experiments show that commercial canning and retorting can be mimicked in an acceptable way using laboratory tests with an autoclave or a simple pressure cooker. The results overall show there is hydrolytic degradation of the melamine cross-linked resins to release additional melamine. There is a strong influence of the temperature of heat treatment applied with foods or simulants but only a minor influence of time of heating and only a minor influence, if any, of food/simulant acidity.

Investigating the Co-Adsorption Behavior of Nucleic-Acid Base (Thymine and Cytosine) and Melamine at Liquid/Solid Interface

NASA Astrophysics Data System (ADS)

Zhao, Huiling; Li, Yinli; Chen, Dong; Liu, Bo

2016-12-01

The co-adsorption behavior of nucleic-acid base (thymine; cytosine) and melamine was investigated by scanning tunneling microscopy (STM) technique at liquid/solid (1-octanol/graphite) interface. STM characterization results indicate that phase separation happened after dropping the mixed solution of thymine-melamine onto highly oriented pyrolytic graphite (HOPG) surface, while the hetero-component cluster-like structure was observed when cytosine-melamine binary assembly system is used. From the viewpoints of non-covalent interactions calculated by using density functional theory (DFT) method, the formation mechanisms of these assembled structures were explored in detail. This work will supply a methodology to design the supramolecular assembled structures and the hetero-component materials composed by biological and chemical compound.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gamboa da Costa, Gonçalo, E-mail: goncalo.gamboa@fda.hhs.gov; Jacob, Cristina C.; Von Tungeln, Linda S.

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 weremore » 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.« less

Water-Compatible Polymer Concrete Materials for use in Rapid Repair Systems for Airport Runways

DTIC Science & Technology

1981-03-01

resin systems, resorcinol phenol- formaldehyde (RPF), urea - formaldehyde (UF), melamine - formaldehyde (MF), and furfuryl alcohol (FA), were selected for...type polymer systems. Phenol- formaldehyde (PF), melamine - formaldehyde (MF), urea -formalde- hyde (UF), and furfuryl alcohol (FA) monomers contain OH and...1-1.5) (1-2) Urea - formaldehyde NH2 CONH2 - HCHO Liquid 7150 (1.0) (1.5-2.5) Melamine - formaldehyde NH2 C:NC(NH2 ):NC(N’H2

Colorimetric detection of melamine in milk by using gold nanoparticles-based LSPR via optical fibers

PubMed Central

Chang, Keke; Wang, Shun; Zhang, Hao; Guo, Qingqian; Hu, Xinran; Lin, Zhili; Sun, Haifeng; Jiang, Min

2017-01-01

A biosensing system with optical fibers is proposed for the colorimetric detection of melamine in liquid milk samples by using the localized surface plasmon resonance (LSPR) of unmodified gold nanoparticles (AuNPs). The biosensing system consists of a broadband light source that covers the spectral range from 200 nm to 1700 nm, an optical attenuator, three types of 600 μm premium optical fibers with SMA905 connectors and a miniature spectrometer with a linear charge coupled device (CCD) array. The biosensing system with optical fibers is low-cost, simple and is well-proven for the detection of melamine. Its working principle is based on the color changes of AuNPs solution from wine-red to blue due to the inter-particle coupling effect that causes the shifts of wavelength and absorbance in LSPR band after the to-be-measured melamine samples were added. Under the optimized conditions, the detection response of the LSPR biosensing system was found to be linear in melamine detection in the concentration range from 0μM to 0.9 μM with a correlation coefficient (R2) 0.99 and a detection limit 33 nM. The experimental results obtained from the established LSPR biosensing system in the actual detection of melamine concentration in liquid milk samples show that this technique is highly specific and sensitive and would have a huge application prospects. PMID:28475597

Assessing Risk-Based Upper Limits of Melamine Migration from Food Containers.

PubMed

Ling, Min-Pei; Lien, Keng-Wen; Hsieh, Dennis P H

2016-12-01

Melamine contamination of food has become a major food safety issue because of incidents of infant disease caused by exposure to this chemical. This study was aimed at establishing a safety limit in Taiwan for the degree of melamine migration from food containers. Health risk assessment was performed for three exposure groups (preschool children, individuals who dine out, and elderly residents of nursing homes). Selected values of tolerable daily intake (TDI) for melamine were used to calculate the reference migration concentration limit (RMCL) or reference specific migration limit (RSML) for melamine food containers. The only existing values of these limits for international standards today are 1.2 mg/L (0.2 mg/dm 2 ) in China and 30 mg/L (5 mg/dm 2 ) in the European Union. The factors used in the calculations included the specific surface area of food containers, daily food consumption rate, body weight, TDI, and the percentile of the population protected at a given migration concentration limit (MCL). The results indicate that children are indeed at higher risk of melamine exposure at toxic levels than are other groups and that the 95th percentile of MCL (specific surface area = 5) for children aged 1-6 years should be the RMCL (0.07 mg/dm 2 ) for protecting the sensitive and general population. © 2016 Society for Risk Analysis.

Adsorptive Removal of Artificial Sweeteners from Water Using Metal-Organic Frameworks Functionalized with Urea or Melamine.

PubMed

Seo, Pill Won; Khan, Nazmul Abedin; Hasan, Zubair; Jhung, Sung Hwa

2016-11-02

A highly porous metal-organic framework (MOF), MIL-101, was modified to introduce urea or melamine via grafting on open metal sites of the MOF. Adsorptive removal of three artificial sweeteners (ASWs) was studied using the MOFs, with or without modifications (including nitration), and activated carbon (AC). The adsorbed quantities (based on the weight of the adsorbent) of saccharin (SAC) under various conditions decreased in the order urea-MIL-101 > melamine-MIL-101 > MIL-101 > AC > O 2 N-MIL-101; however, the quantities based on unit surface area are in the order melamine-MIL-101 > urea-MIL-101 > MIL-101 > O 2 N-MIL-101. Similar ASWs [acesulfame (ACE) and cyclamate (CYC)] showed the same tendency. The mechanism for very favorable adsorption of SAC, ACE, and CYC over urea- and melamine-MIL-101 could be explained by H-bonding on the basis of the contents of -NH 2 groups on the MOFs and the adsorption results under a wide range of pH values. Moreover, the direction of H-bonding could be clearly defined (H acceptor: ASWs; H donor: MOFs). Urea-MIL-101 and melamine-MIL-101 could be suggested as competitive adsorbents for organic contaminants (such as ASWs) with electronegative atoms, considering their high adsorption capacity (for example, urea-MIL-101 had 2.3 times the SAC adsorption of AC) and ready regeneration.

Melamine milk powder and infant formula sold in East Africa.

PubMed

Schoder, Dagmar

2010-09-01

This is the first study proving the existence of melamine in milk powder and infant formula exported to the African market. A total of 49 milk powder batches were collected in Dar-es-Salaam (Tanzania, East Africa), the center of international trade in East Africa, which serves as a commercial bottleneck and shipment hub for sub-Saharan, Central, and East Africa. Two categories of samples were collected between October and December 2008, immediately after the melamine contamination of Chinese products became public: (i) market brands of all international companies supplying the East African market and (ii) illegally sold products from informal channels. Melamine concentration was determined with the AgraQuant Melamine Sensitive Assay. Despite the national import prohibition of Chinese milk products and unlabeled milk powder in Tanzania, 11% (22 of 200) of inspected microretailers sold milk powder on the local black market. Manufacturers could be identified for only 55% (27) of the 49 investigated batches. Six percent (3 of 49) of all samples and 11% (3 of 27) of all international brand name products tested revealed melamine concentrations up to 5.5 mg/kg of milk powder. This amount represents about twice the tolerable daily intake as suggested by the U.S Food and Drug Administration. Based on our study, we can assume that the number of affected children in Africa is substantial.

Melamine sensing based on evanescent field enhanced optical fiber sensor

NASA Astrophysics Data System (ADS)

Luo, Ji; Yao, Jun; Wang, Wei-min; Zhuang, Xu-ye; Ma, Wen-ying; Lin, Qiao

2013-08-01

Melamine is an insalubrious chemical, and has been frequently added into milk products illegally, to make the products more protein-rich. However, it can cause some various diseases, such as kidney stones and bladder cancer. In this paper, a novel optical fiber sensor with high sensitivity based on absorption of the evanescent field for melamine detection is successfully proposed and developed. Different concentrations of melamine changing from 0 to 10mg/mL have been detected using the micro/nano-sensing fiber decorated with silver nanoparticles cluster layer. As the concentration increases, the sensing fiber's output intensity gradually deceases and the absorption of the analyte becomes large. The concentration changing of 1mg/ml can cause the absorbance varying 0.664 and the limit of the melamine detectable concentration is 1ug/mL. Besides, the coupling properties between silver nanoparticles have also been analyzed by the FDTD method. Overall, this evanescent field enhanced optical fiber sensor has potential to be used in oligo-analyte detection and will promote the development of biomolecular and chemical sensing applications.

NASA Engineering and Safety Center (NESC) Enhanced Melamine (ML) Foam Acoustic Test (NEMFAT)

NASA Technical Reports Server (NTRS)

McNelis, Anne M.; Hughes, William O.; McNelis, Mark E.

2014-01-01

The NASA Engineering and Safety Center (NESC) funded a proposal to achieve initial basic acoustic characterization of ML (melamine) foam, which could serve as a starting point for a future, more comprehensive acoustic test program for ML foam. A project plan was developed and implemented to obtain acoustic test data for both normal and enhanced ML foam. This project became known as the NESC Enhanced Melamine Foam Acoustic Test (NEMFAT). This document contains the outcome of the NEMFAT project.

Quantification of melamine in drinking water and wastewater by micellar liquid chromatography.

PubMed

Beltrán-Martinavarro, Beatriz; Peris-Vicente, Juan; Rambla-Alegre, Maria; Marco-Peiró, Sergio; Esteve-Romero, Josep; Carda-Broch, Samuel

2013-01-01

Because of the large potential health impact caused by deliberate contamination with the synthetic chemical melamine of different products for human and animal consumption, the World Health Organization and the Food and Agriculture Organization of the United Nations provided a range of recommendations in order to facilitate obtaining needed data, among which was the determination of the background levels of melamine in drinking water and wastewater (December 4, 2008). A chromatographic procedure using a C18 column, a micellar mobile phase consisting of sodium dodecyl sulfate (0.1 M), and 1-propanol (7.5%) buffered at pH 3, and detection by absorbance at 210 nm is reported in this paper for the quantification of melamine in drinking water and wastewater. Samples were filtered and directly injected into the chromatographic system, thus avoiding an extraction procedure. The optimal mobile phase composition was obtained by a chemometrics approach that considered the retention factor, efficiency, and peak shape. Melamine was eluted in about 6.2 min without interferences. Validation was performed following U.S. Food and Drug Administration guidelines. The analytical parameters studied were linearity (0.03-5 microg/mL, R2 = 0.998), LOD (13 nglmL), intraday and interday accuracy (between 4.1 and 12.2%), intraday and interday precision (less than 14.8%), and robustness (RSD < 5.1% for retention time and <9.0% for area). The proposed methodology was successfully applied for analysis of local wastewater and drinking water, in which no melamine was found.

Simultaneous enzymatic and SERS properties of bifunctional chitosan-modified popcorn-like Au-Ag nanoparticles for high sensitive detection of melamine in milk powder.

PubMed

Li, Junrong; Zhang, Guannan; Wang, Lihua; Shen, Aiguo; Hu, Jiming

2015-08-01

In this work, we suggest a chitosan-modified popcorn-like Au-Ag nanoparticles (CSPNPs) based assay for high sensitive detection of melamine, in which CSPNPs not only provide with an intrinsic peroxidase-like activity but also act as surface enhanced Raman scattering (SERS) substrates. CSPNPs can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to the charge transfer complex (CTC), which contributes to a tremendous surface-enhanced resonant Raman scattering (SERRS) signals with 632.8 nm laser excitation. The target molecule melamine can generate an additional compound with H2O2, which means the available amount of H2O2 for the oxidation of TMB reduced. Correspondingly, the SERRS intensity of CTC is decreased. The decreased Raman intensity is proportional to the concentration of melamine over a wide range from 10 nM to 50 μM (R(2)=0.989), with a limit of detection (LOD) of 8.51 nM. Moreover, the proposed highly selective method is fully capable of rapid, separation-free detection of melamine in milk powder. Copyright © 2015 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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.

Selective delivery of 2-hydroxy APA to Trypanosoma brucei using the melamine motif

PubMed Central

Klee, Nina; Wong, Pui Ee; Baragaña, Beatriz; Mazouni, Farah El; Phillips, Margaret A.; Barrett, Michael P.; Gilbert, Ian H.

2010-01-01

Trypanosoma brucei, the parasite that causes human African trypanosomiasis, is auxotrophic for purines and has specialist nucleoside transporters to import these metabolites. In particular, the P2 aminopurine transporter can also selectively accumulate melamine derivatives. In this Letter, we report the coupling of the melamine moiety to 2-hydroxy APA, a potent ornithine decarboxylase inhibitor, with the aim of selectively delivering this compound to the parasite. The best compound described here shows an increased in vitro trypanocidal activity compared with the parent. PMID:20615694

Precursor polymer compositions comprising polybenzimidazole

DOEpatents

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.

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

DOEpatents

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.

Experimental Evaluation of Equivalent-Fluid Models for Melamine Foam

NASA Technical Reports Server (NTRS)

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.

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

PubMed Central

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

2017-01-01

Abstract 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. PMID:29491791

Risk factors for acute kidney injury (AKI) in infants with melamine-associated urolithiasis and follow-up: a multi-center retrospective analysis.

PubMed

He, Qiqi; Yue, Zhongjin; Tang, XiaoShuang; Chang, Hong; Wang, Wei; Shi, Wei; Wang, Zhiping; Shang, Panfeng

2014-10-01

Abstract An epidemic of urinary tract stones was noted among infants in China, 2008. This event was believed to be associated with consumption melamine-contaminated powdered formula. The patients with symptoms and clinical manifests had already been analyzed in our previous studies. In this study, our aim is to investigate the risk factors of melamine-associated acute kidney injury (AKI) and the potential relationship toward children growth in our five years follow-up. A total of 619 infants with melamine-associated urolithiasis were admitted into 20 different hospitals in the Gansu province, China. All clinical data were divided into AKI and control groups according to the occurrence of AKI. Univariate and multivariate analyses were performed with a logistic regression model to assess the independent risk factors of AKI. Logistic regression analysis revealed that the odds ratio (OR) of AKI was 19.62 in the group of infants who consumed Sanlu® milk powdered infant milk formula. A higher prevalence of AKI was observed in infants age of 6-11 months (OR: 9.59, p < 0.01) and 12-17 months (OR: 5.06, p < 0.01). Multivariate analysis also indicated that any one symptoms of upper respiratory tract infection (URTI), diarrhea, dehydration and fever (OR: 4.29, p < 0.01) were independent risk factors of AKI. Therefore, this study demonstrated that high melamine infant formula (Sanlu® milk powdered infant formula), age (6-17 months) and symptoms of URTI, diarrhea, dehydration or fever were risk factors of AKI in infants with melamine-associated urolithiasis.

Solid-state supramolecular architectures formed by co-crystallization of melamine and 2-, 3- and 4-fluorophenylacetic acids

NASA Astrophysics Data System (ADS)

Perpétuo, Genivaldo Julio; Janczak, Jan

2018-01-01

A family of supramolecular complexes of melamine with fluorophenylacetic acid isomers using solvent-assisted and evaporation-based techniques has been prepared. Crystallization of melamine with 2-fluorophenylacetic acid yield hydrated ionic supramolecular complex (1), whereas crystallization of melamine with 3- and 4-fluorophenylacetic acids leads to formation of neutral supramolecular complexes (2, 3), all with base to acid ratio of 1:2. The supramolecular assembly is driven by the noncovalent interactions, most commonly by the hydrogen bonds. The components of the crystal 1 interact via Nsbnd H⋯O and Osbnd H⋯N hydrogen bonds with R22(8) and R32(10) graphs forming ionic supramolecular complex, whereas the components in the crystals 2 and 3 interact with a graph of R22(8) forming neutral supramolecular complexes. The singly protonated melamin-1-ium residues in 1 interact each other via a pair of Nsbnd H⋯N hydrogen bonds forming one dimensional chains along [-110] that interact via Nsbnd H⋯O with deprotonated and neutral 2-fluorophenylacetic acid units and water molecules forming ribbon. In 2 and 3 co-crystals the melamine interacts with 3- and 4-fluorophenylacetic acids via a pair of Nsbnd H⋯O hydrogen bonds forming pseudo one-dimensional supramolecular chains along [010] direction. Hirshfeld surface and analysis of 2D fingerprint plots have been analysed both quantitatively and qualitatively interactions that governing the supramolecular organisation. The IR and Raman vibrational characterization of the supramolecular complexes 1-3 was supported by the spectra of their deuterated analogues.

Melamine-contaminated milk products induced urinary tract calculi in children.

PubMed

Zhang, Li; Wu, Ling-Ling; Wang, Ya-Ping; Liu, Ai-Min; Zou, Chao-Chun; Zhao, Zheng-Yan

2009-02-01

Melamine is an industrial chemical used primarily as plastics stabilizer and fire retardant. On September 11, 2008, melamine-contaminated milk products were reported to be responsible for urinary tract calculi in infants and children in China. This study aimed to investigate the prevalence, lesions, risk factors, clinical features, and management of children fed with the melamine-contaminated milk products. A total of 15 577 infants and children fed with the milk products were screened at our hospital. Ultrasonography was performed in all the infants and children. For those found with urinary tract calculion ultrasonography, urnalysis was done. Among them, 846 with detailed data screened from September 17 to 25 were enrolled for further analysis in this study. They were divided into calculus group (326 children) and non-calculus group (520 children) according to the results of ultrasonography. They included 429 boys and 417 girls, aged from 1 month to 5 years (median, 18 months). Their clinical and laboratory data, ultrasonograms, and treatment results were analyzed. Of the 15 577 children screened, 562 (3.61%) had urinary tract calculi. The rate was closely related to the melamine concentration in patients fed with formula. In 846 children with detailed data enrolled in this analysis, weight and head circumference Z scores in the calculus group were lower than those in the non-calculus group (P=0.048, P=0.046). Long duration of formula feeding, high melamine contained formula, and minimal water intake were the risk factors for calculi (P<0.05, respectively). Of 326 children with calculi, 281 had small calculiless than 0.5 cm in diameter, 227 had multiple calculi, and 34 had urinary tract distention. Moreover, diffuse renal lesions, renal failure and ascites were noted in 4, 3 and 2 patients, respectively. After 1-month treatment with sodium bicarbonate and Chinese traditional medicine, calculi disappeared in 49 of 54 outpatients. In 41 inpatients, 5 had calculi removed operatively and 36 had calculi minimized. Melamine-contaminated milk products induced urinary tract calculi, which have a good response to conservative therapy. Long-term follow-up of infants and children fed with melamine-contaminated milk products is required, and food safety should be supervised increasingly for the health of children.

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

PubMed

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 475 cm(-1).

Hydrogen-bonding patterns in 5-fluoro-cytosine-melamine co-crystal (4/1).

PubMed

Mohana, Marimuthu; Muthiah, Packianathan Thomas; Sanjeewa, Liurukara D; McMillen, Colin D

2016-04-01

The asymmetric unit of the title compound, 4C4H4FN3O·C3H6N6, comprises of two independent 5-fluoro-cytosine (5FC) mol-ecules (A and B) and one half-mol-ecule of melamine (M). The other half of the melamine mol-ecule is generated by a twofold axis. 5FC mol-ecules A and B are linked through two different homosynthons [R 2 (2)(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 mol-ecules A and B inter-act with the N2 amino group on both sides of the melamine mol-ecule, forming a DDAA array of quadruple hydrogen bonds and generating a supra-molecular pattern. The 5FC (mol-ecules A and B) and two melamine mol-ecules inter-act via N-H⋯O, N-H⋯N and N-H⋯O, N-H⋯N, C-H⋯F hydrogen bonds forming R 6 (6)(24) and R 4 (4)(15) ring motifs. The crystal structure is further strengthened by C-H⋯F, C-F⋯π and π-π stacking inter-actions.

Clinical observation of childhood urinary stones induced by melamine-tainted infant formula in Anhui province, China

PubMed Central

Wang, Jing; Hu, Bo; Lu, Ling; Zhang, Min

2013-01-01

Introduction The current report detailed an investigation of melamine-linked urinary stones in children exposed to contaminated formula. Material and methods A total of 1062 children fed with melamine-contaminated infant formula were screened for urinary stones. Sixty healthy children without melamine exposure were recruited as a control group. Ultrasonography of the urinary tract system was performed. Urinalysis, renal function, liver status, and serum electrolytes were determined. Results We encountered 49 affected children from the 1062 screened ones, at a rate of 4.6% per ultrasound performed. Thirty-two were male, and 17 were female. The affected children ranged in age from 1 month to 96 months, with a mean of 25 months. Duration of exposure was from 1.3 months to 84 months, with a mean of 19.5 months. The melamine contents in serum were between 12 mg/kg and 2563 mg/kg, with mean concentration of 1295.3 mg/kg. Most affected children were asymptomatic with no urinary findings. Patients with urinary stones exhibited lower urine pH and serum HCO3 – than those in the healthy children, whereas for serum uric acid, alanine aminotransferase, aspartate aminotransferase, and anion gap the opposite trends were observed. The stone diameter ranged from 2 mm to 18 mm with a median of 6.5 mm. Multiple stones were noted in all patients. After 1 week of conservative management, stone diameters of 38 cases (77.6%) were significantly decreased. Among them, urinary stones were discharged completely in 21 affected children (42.9%). Conclusions The short-term outcome of melamine-linked urinary stones is satisfactory. PMID:23515431

Urinary tract abnormalities in Chinese rural children who consumed melamine-contaminated dairy products: a population-based screening and follow-up study

PubMed Central

Liu, Jian-meng; Ren, Aiguo; Yang, Lei; Gao, Jinji; Pei, Lijun; Ye, Rongwei; Qu, Quangang; Zheng, Xiaoying

2010-01-01

Background Kidney damage related to consumption of melamine-contaminated dairy products by young children in China has been described. However, no studies have reported on the population-based prevalence of kidney damage among exposed children or on the condition of affected children after follow-up. Methods We conducted an ultrasound-based screening in September 2008 of 7933 children younger than 36 months of age who lived in a rural area in China where the dairy products most highly contaminated with melamine were sold. We monitored children who had evidence of nephrolithiasis or hydronephrosis at screening using renal ultrasonography after one, three and six months. We also collected information from the mothers of affected children about consumption of melamine-contaminated products between June and August 2008. Results The overall prevalence of urinary tract abnormalities among screened children was 0.61% (95% confidence interval [CI] 0.45%–0.80%). The mean exposure dose of melamine was estimated to be 116 (range 36–220) mg per day. Of the 48 affected children, 43 (89.6%) were asymptomatic, 2 had symptoms and were hospitalized, and 3 had symptoms but treatment had been not sought for them. Of the 46 children for whom six-month follow-up information was available, renal abnormalities persisted in 5 children and resolved in the remaining 41. Interpretation Among children who underwent screening, 0.61% showed ultrasonographic evidence of nephrolithiasis or hydronephrosis. Most of the affected children were asymptomatic. The majority of the affected children recovered from the toxic effects of melamine over time without specific treatment. Renal abnormalities remained in 12% of the affected children. PMID:20176755

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

PubMed Central

Mohana, Marimuthu; Muthiah, Packianathan Thomas; Sanjeewa, Liurukara D.; McMillen, Colin D.

2016-01-01

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 [R 2 2(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 R 6 6(24) and R 4 4(15) ring motifs. The crystal structure is further strengthened by C—H⋯F, C—F⋯π and π–π stacking inter­actions. PMID:27375887

One year follow up of the outcomes of child patients with melamine-related kidney stones in Beijing and surrounding provinces in China.

PubMed

Shen, Ying; Sun, Qiang; Gao, Jie; Jia, Li-Qun; Sun, Ning; Pan, Yue-Song; Liu, Xiao-Mei; Liu, Xiao-Rong; Wang, Yu; Wu, Dong-Xue; Jiang, Ye-Ping

2011-05-01

To evaluate their prognosis, the damage by melamine on children's kidney and other organs, and its influence on the children's development, was investigated. Nine hundred and sixty-two Chinese children were divided into three groups: group A, 265 children diagnosed with melamine-associated urolithiasis; group B, 197 children with a history of melamine-contaminated milk powder consumption but without urolithiasis; and group C, 500 healthy children. They were examined at 0, 1, 3, 6 and 12 months. The factors influencing the prognosis were investigated. The stone discharge was monitored by ultrasonography. Overt renal and liver damage and underlying renal injury markers were analyzed. The stone discharge rates 1, 3, 6 and 12 months after the diagnoses were 52.5%, 67.2%, 88.3% and 95.5%, respectively. Stone size was a stable influencing factor for the stone discharge rate. Additionally, the values of the potential renal injury markers in children with stones already discharged is equivalent to normal children. This 12 month follow up of early renal injury markers indicated that the damage to the kidney is temporary with no persistent negative outcomes being found till now. Additionally, the gross development of the children seemed not yet jeopardized by melamine. Longer-term follow up will be conducted. © 2011 The Authors. Nephrology © 2011 Asian Pacific Society of Nephrology.

Baseline levels of melamine in food items sold in Canada. II. Egg, soy, vegetable, fish and shrimp products.

PubMed

Tittlemier, Sheryl A; Lau, Benjamin P-Y; Ménard, Cathie; Corrigan, Catherine; Sparling, Melissa; Gaertner, Dean; Cao, Xu-Liang; Dabeka, Bob; Hilts, Carla

2010-01-01

A variety of egg-containing, soy-based, fish, shrimp and vegetable products sold in Canada were analysed for melamine (MEL) using a sensitive solid-phase extraction LC-MS/MS analytical method. MEL was detected above the method quantification limit of 0.004 mg/kg in 98 of the 378 samples analysed. Concentrations in the various food product groups ranged 0.00507-0.247 mg/kg (egg-containing items), 0.00408-0.0479 mg/kg (soy-based meat substitutes), 0.00409-1.10 mg/kg (fish and shrimp products), and 0.00464-0.688 mg/kg (vegetable products). MEL was detected less frequently in egg- and soy-containing products. The presence of MEL in most of the Canadian Total Diet Study shrimp composites collected after 2001 suggested the residues in shrimp were caused by a relatively recent exposure to MEL. All concentrations of MEL reported were lower than the 2.5 mg/kg interim standard established for MEL in items containing milk and milk-derived ingredients and the respective maximum residue limits for cyromazine and its metabolite, melamine, in vegetables set by the Canadian Government (2009; http://www.hc-sc.gc.ca/fn-an/securit/chem-chim/melamine/qa-melamine-qr-eng.php#8 ). The consumption of foods containing these low levels of MEL does not constitute a health risk for consumers.

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

EPA Science Inventory

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...

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

USDA-ARS?s Scientific Manuscript database

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...

Raman spectral imaging technique on detection of melamine in skim milk powder

USDA-ARS?s Scientific Manuscript database

A point-scan Raman spectral imaging system was used for quantitative detection of melamine in milk powder. A sample depth of 2 mm and corresponding laser intensity of 200 mW were selected after evaluating the penetration of a 785 nm laser through milk powder. Horizontal and vertical spatial resoluti...

Effects of the adulteration technique on the near-infrared detection of melamine in milk powder

USDA-ARS?s Scientific Manuscript database

The fraudulent adulteration of protein-rich food ingredients with melamine in 2007 and 2008 highlighted the public health and economic consequences of adulterating foods with chemicals not approved for food use. U.S. Pharmacopeia is leading a collaborative project to develop reference materials as w...

Superior capacitive performance of hydrochar-based porous carbons in aqueous electrolytes.

PubMed

Fuertes, Antonio B; Sevilla, Marta

2015-03-01

Biomass-based highly porous carbons with excellent performances in aqueous electrolyte-based supercapacitors have been developed. The synthesis of these materials is based on the chemical activation of biomass-based hydrochar. The addition of melamine to the activation mixture leads to porous carbons with a porosity consisting of micropores/small mesopores. Furthermore, melamine promotes the introduction of nitrogen heteroatoms in the carbon framework, along with abundant oxygen functionalities, to improve the wettability. The materials produced in the presence or absence of melamine exhibit high specific capacitances in aqueous electrolytes (>270 F g(-1) in H2 SO4 and >190 F g(-1) in Li2SO4). Additionally, the mesopores present in the melamine-based micro-/mesoporous carbons notably improve the ion-transport kinetics, especially in Li2SO4. Furthermore, in Li2SO4, they remain stable up to a cell voltage of 1.6 V; thus exhibiting superior energy and power characteristics than those in H2 SO4. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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.

Mechanochemical route to the synthesis of nanostructured Aluminium nitride

PubMed Central

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

Acoustic Test Results of Melamine Foam with Application to Payload Fairing Acoustic Attenuation Systems

NASA Technical Reports Server (NTRS)

Hughes, William O.; McNelis, Anne M.

2014-01-01

A spacecraft at launch is subjected to a harsh acoustic and vibration environment resulting from the passage of acoustic energy, created during the liftoff of a launch vehicle, through the vehicle's payload fairing. In order to ensure the mission success of the spacecraft it is often necessary to reduce the resulting internal acoustic sound pressure levels through the usage of acoustic attenuation systems. Melamine foam, lining the interior walls of the payload fairing, is often utilized as the main component of such a system. In order to better understand the acoustic properties of melamine foam, with the goal of developing improved acoustic attenuation systems, NASA has recently performed panel level testing on numerous configurations of melamine foam acoustic treatments at the Riverbank Acoustical Laboratory. Parameters assessed included the foam's thickness and density, as well as the effects of a top outer cover sheet material and mass barriers embedded within the foam. This testing followed the ASTM C423 standard for absorption and the ASTM E90 standard for transmission loss. The acoustic test data obtained and subsequent conclusions are the subjects of this paper.

Experimental and numerical investigations on melamine wedges.

PubMed

Schneider, S

2008-09-01

Melamine wedges are often used as acoustic lining material for anechoic chambers. It was proposed here to study the effects of the mounting conditions on the acoustic properties of the melamine wedges used in the large anechoic chamber at the LMA. The results of the impedance tube measurements carried out show that the mounting conditions must be taken into account when assessing the quality of an acoustic lining. As it can be difficult to simulate these mounting conditions in impedance tube experiments, a numerical method was developed, which can be used to complete the experiments or for parametric studies. By combining the finite and the boundary element method, it is possible to investigate acoustic linings with almost no restrictions as to the geometry, material behavior, or mounting conditions. The numerical method presented here was used to study the acoustic properties of the acoustic lining installed in the anechoic chamber at the LMA. Further experiments showed that the behavior of the melamine foam is anisotropic. Numerical simulations showed that this anisotropy can be used to advantage when designing an acoustic lining.

Flexible and Hierarchical Metal-Organic Framework Composites for High-Performance Catalysis.

PubMed

Huang, Ning; Drake, Hannah; Li, Jialuo; Pang, Jiangdong; Wang, Ying; Yuan, Shuai; Wang, Qi; Cai, Peiyu; Qin, Junsheng; Zhou, Hong-Cai

2018-05-18

The development of new types of porous composite materials is of great significance owing to their potentially improved performance over those of individual components and extensive applications in separation, energy storage, and heterogeneous catalysis. In this work, we integrated mesoporous metal-organic frameworks (MOFs) with macroporous melamine foam (MF) using a one-pot process, generating a series of MOF/MF composite materials with preserved crystallinity, hierarchical porosity, and increased stability over that of melamine foam. The MOF nanocrystals were threaded by the melamine foam networks, resembling a ball-and-stick model overall. As a proof-of-concept study, the resulting MOF/MF composite materials were employed as an effective heterogeneous catalyst for the epoxidation of cholesteryl esters. Combining the advantages of interpenetrative mesoporous and macroporous structures, the MOF/melamine foam composite provided higher dispersibility and more accessibility of catalytic sites, exhibiting excellent catalytic performance. This strategy constitutes an important step forward the development of other MOF composites and exploration of their high-performance catalysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diagnosis, treatment and follow-up of 25 patients with melamine-induced kidney stones complicated by acute obstructive renal failure in Beijing Children's Hospital.

PubMed

Sun, Qiang; Shen, Ying; Sun, Ning; Zhang, Gui Ju; Chen, Zhi; Fan, Jian Feng; Jia, Li Qun; Xiao, Hong Zhan; Li, Xu Ran; Puschner, Birgit

2010-04-01

A total of 25 Chinese patients aged 6 to 36 months hospitalised at Beijing Children's Hospital due to melamine-induced kidney stones complicated by acute obstructive renal failure in 2008 were included in a study in order to diagnose and treat these special cases more effectively. Feeding history, clinical presentation, ultrasound findings, treatments and effects were summarised. Twelve to seventeen months follow-up was reported also. Ultrasound examination showed that calculi were located at the kidney and ureters. Stones were composed of both uric acid and melamine in a molar ratio of 1.2:1 to 2.1:1. Treatments providing liquid plus alkalisation of urine proved to be effective in helping the patients pass the stones. Surgical intervention was needed in severe cases. Renal function returned to normal in all 25 patients after various durations of therapy. Sixty-eight percent of the patients expelled all of the calculi within 3 months, 90% in 6 months and 95% in 9 months, without sequelae till now. Melamine-contaminated milk formula can cause kidney stones in infants, which should be diagnosed by feeding history, clinical symptoms and ultrasound examination. Composition of the stones was not only of melamine but also uric acid. Providing liquid orally or intravenously plus alkalisation of urine proved to promote the removal of the stones. Follow-up of 12 to 17 months after discharge showed no sequelae.

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

NASA Astrophysics Data System (ADS)

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.

Preparation of Proton Exchange Membranes and Lithium Batteries from Melamine-containing Ormosils

NASA Technical Reports Server (NTRS)

Tigelaar, Dean M.; Kinder, James D.; Meador, Mary Ann; Waldecker, James; Bennett, William R.

2004-01-01

Our laboratory has recently reported a series of rodcoil polymers for lithium batteries that display dimensionally stable films with good ionic conductivity. The rod segments consist of rigid linear and branched polyimides and the coil segments are polyethylene oxides (PEO). It has been proposed that good mechanical and transport properties are due to phase separation between the rod and coil segments. It was also observed that increased branching and molecular weight lead to increased conductivity. The following study was undertaken to assess the effects of phase separation in polyalkylene oxides connected by melamine linkages. Melamine was chosen as the linking unit because it provides a branching site, cation binding sites to help ionic transport between polymer chains, and the opportunity for self assembly through hydrogen bonding. Polymers were made by the reaction of cyanuric chloride with a series of amine-terminated alkylene oxides. A linear polymer was first made, followed by reaction of the third site on cyanuric chloride with varying ratios of monofunctional Jeffamine and (3-aminopropyl)triethoxysilane. The lithium trifluoromethane sulfonamide-doped polymers are then crosslinked through a sol-gel process to form free-standing films. Initial results have shown mechanically strong films with lithium conductivities on the order of 2 x 10(exp -5) S/cm at ambient temperature. In a separate study, organically modified silanes (Ormosils) that contain sulfonic acid derivatized melamines have been incorporated into proton exchange membranes. The membranes are made by reaction of the primary amine groups of various ratios of melamine derivative and difunctional Jeffamine (MW = 2000) with the epoxide group of (3-Glycidyloxypropyl)trimethoxysilane. The films were then cross-linked through a sol-gel process. Resulting sulfuric acid doped films are strong, flexible, and have proton conductivities on the order of 2 x l0(exp -2) S/cm (120 C, 25% relative humidity). Our best results have been observed when films contain 60% PEO and 40% sulfonated melamine.

Technical Reliability Studies. EOS/ESD Technology Abstracts

DTIC Science & Technology

1981-01-01

MECHANISMS MELAMINE MESFETS MICROWAVE MIS 15025 AUTOMATIC MACHINE PRECAUTIONS FOR HOS/OiOS 15006 INSTRUCTIONS FOR INSTALLATION AND...ELIMINATION OF EOS INDUCED SECONDARY FAILURE MECHANISMS 15000 USE OF MELAMINE WORK-SURFACE FOR ESD POTENTIAL BLEED OFF 16141 MICROWAVE NANOSECOND... microwave devices, optoelectronics, and selected nonelectronic parts employed in military, space and commercial applications. In addition, a System

A method based on coffee-ring deposition confocal Raman spectroscopy of analysis of melamine in milk

NASA Astrophysics Data System (ADS)

Tan, Zong; Chen, Da

2016-10-01

In this work, an economical and high-efficiency method for detection of melamine in milk was developed. The enrichment effect of coffee-ring was combined with the micro-region analysis of confocal Raman spectroscopy, in addition, assisted with chemometric algorithmthe. Consequently, a desired result was obtained that the LOD of melamine in this method was 1 ppm, which was excellent because the sensitivity of conventional Raman detection was generally low. Furthermore, the whole process were processed in an easily available condition with almost no chemical reagents consumption, and the chosen substrates for the formation of coffee-ring were reusable. Thus, the method is environmental friendly and has a great potential application in food safety inspection.

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

USDA-ARS?s Scientific Manuscript database

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 ...

Surface modification of melamine sponges for pH-responsive oil absorption and desorption

NASA Astrophysics Data System (ADS)

Lei, Zhiwen; Zhang, Guangzhao; Deng, Yonghong; Wang, Chaoyang

2017-09-01

Inspired by the development of smart oil/water separation materials, a pH responsive melamine sponge has been obtained by grafting poly (4-vinylpyridine) on the skeleton surface through atom transfer radical polymerization. Through scanning electron microscopy and x-ray photoelectron spectroscopy, the successful grafting of poly (4-vinylprridine) onto the melamine sponge has been confirmed. When contacting with different pH water droplets in air, the as-prepared product shows excellent switchable wettability between super-hydrophilicity (0°) and highly hydrophobicity (135°). Meanwhile, this responsive sponge also exhibits super-hydrophilic/oleophobic property underwater at pH = 1.0, and highly hydrophobic/super-oleophilic property in neutral solution at pH = 7.0. Furthermore, the excellent responsiveness is remained after five cycle water contact angle tests between two different pH stages at pH 1.0 and 7.0. The modified melamine sponges could not only absorb the oil from the oily water at pH = 7.0, but also quickly release the absorbed oil underwater at pH = 1.0 without leaving any residues and hurting the environment nearly, showing a good potential in controlled oil/water separation and oil recovery.

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Melamine-induced urinary calculi in infants--sonographic manifestations and outcomes 1 year after exposure.

PubMed

Nie, Fang; Li, Xin-jie; Shang, Pan-feng; Wang, Ying

2013-04-01

In 2008, the melamine-tainted-milk incident started with reports of increased incidence of urolithiasis in infants in China. Affected children were screened for urolithiasis. The purpose of this study was to analyze sonographic characterization of infant melamine-induced urolithiasis. Transabdominal US examination was done in 603 infants with melamine-induced calculi. The imaging characteristics of calculi and hydronephrosis were analyzed. Follow-up US imaging was performed. Comet-tail sign was seen behind the calculus of <4 mm. Calculi of ≥ 4 mm were found in 299 inpatients with clear posterior border and with or without light shadowing. Solitary and multiple stones had similar incidence. Incidence of calculi in the inferior renal calyx was the highest (55.2%) in inpatients. Calculus size in inpatients age 2-3 years was smaller than that of children younger than 2 years old (P < 0.05). Inpatients age 2-3 years had the highest incidence rate (48.0%) of hydronephrosis. Calculi of <4 mm manifested as hyperechoic foci near the renal papillae, while calculi of ≥ 4 mm usually manifested as echogenic foci with visible inferior edge in the renal calyx. Hydronephrosis was a common imaging finding in inpatients ages 2-3 years.

Electrostatic Discharge Training Manual

DTIC Science & Technology

1980-09-01

CAN BE MOLDED INTO FORMED SHAPES. FIBERBOARD, MELAMINE LAMINATES AND OTHER MATERIALS (LAMINATED OR HOMOGENEOUS) CAN BE CONSTRUCTED INTO BOXES AND...COVERED WITH, ESD PROTECTIVE MATERIALS SUCH AS METAL, MIL-B-81705 TYPE II, MIL-P- 82646 (REFERENCES 17, 16), MELAMINE LAMINATES OR OTHER ESD PROTECTIVE...CONDUCTANCE IN AVALANCHE MICROWAVE OSCILLATORS", IEEE TRANSACTIONS ON ELECTRON DEVICES, ED-i5, JUNE 1968. 32. HOLM, R., ELECTRIC CONTACTS HANDBOOK, BERLIN

Fire Safety Aspects of Polymeric Materials. Volume 8. Land Transportation Vehicles

DTIC Science & Technology

1979-01-01

Resins and Urea - and Melamine - Formaldehyde Resins ," in: Kurylaand Papa (1973). 188 I RtftHfcNCES...ting furfuryl alcohol and an aldehyde — most frequently formaldehyde (Siegfried 1967). Urea is often used as a modifying agent. The resins are hardened... melamine / formaldehyde and phenol/formaldehye resins may find significant utility as a char resistant coating on factory coated wood. 73 /’ I

Diagnosis and treatment of melamine-associated urinary calculus complicated with acute renal failure in infants and young children.

PubMed

Sun, Ning; Shen, Ying; Sun, Qiang; Li, Xu-ran; Jia, Li-qun; Zhang, Gui-ju; Zhang, Wei-ping; Chen, Zhi; Fan, Jian-feng; Jiang, Ye-ping; Feng, Dong-chuan; Zhang, Rui-feng; Zhu, Xiao-yu; Xiao, Hong-zhan

2009-02-05

Infants in some areas of China developed urinary lithiasis after being fed with powdered milk that was tainted with melamine in 2008 and very small proportion of the infants developed acute renal failure caused by urinary tract calculus obstruction. The aim of this article was to summarize clinical characteristics, diagnosis and treatment of infants with urinary calculus and acute renal failure developed after being fed with melamine tainted formula milk. Data of infant patients with urinary calculus and acute renal failure due to melamine tainted formula milk admitted to the Beijing Children's Hospital Affiliated to the Capital Medical University and the Xuzhou Children's Hospital in 2008 were used to analyze the epidemiological characteristics, clinical manifestations, imaging features as well as effects of 4 types of therapies. All the 34 infants with urinary calculus were complicated with acute renal failure, their blood urea nitrogen (BUN) was (24.1+/-8.2) mmol/L and creatinine (Cr) was (384.2+/-201.2) micromol/L. The chemical analysis on the urinary calculus sampled from 15 of the infants showed that the calculus contained melamine and acidum uricum. The time needed for the four types of therapies for returning Cr to normal was (3.5+/-1.9) days for cystoscopy group, (2.7+/-1.1) days for lithotomy group, (3.8+/-2.3) days for dialysis group, and (2.7+/-1.6) days for medical treatment group, which had no statistically significant difference (P=0.508). Renal failure of all the 34 infants was relieved within 1 to 7 days, averaging (3.00+/-1.78) days. Melamine tainted formula milk may cause urinary calculus and obstructive acute renal failure. It is suggested that firstly the patients with urinary calculus complicated with acute renal failure should be treated with dialysis or medication to correct electrolyte disturbance, in particular hyperkalemia, and then relieve the obstruction with available medical and surgical methods as soon as possible. It was observed that the short-term prognosis was satisfactory.

Efficient fluorescence energy transfer system between CdTe-doped silica nanoparticles and gold nanoparticles for turn-on fluorescence detection of melamine.

PubMed

Gao, Feng; Ye, Qingqing; Cui, Peng; Zhang, Lu

2012-05-09

We here report an efficient and enhanced fluorescence energy transfer system between confined quantum dots (QDs) by entrapping CdTe into the mesoporous silica shell (CdTe@SiO₂) as donors and gold nanoparticles (AuNPs) as acceptors. At pH 6.50, the CdTe@SiO₂-AuNPs assemblies coalesce to form larger clusters due to charge neutralization, leading to the fluorescence quenching of CdTe@SiO₂ as a result of energy transfer. As compared with the energy transfer system between unconfined CdTe and AuNPs, the maximum fluorescence quenching efficiency of the proposed system is improved by about 27.0%, and the quenching constant, K(sv), is increased by about 2.4-fold. The enhanced quenching effect largely turns off the fluorescence of CdTe@SiO₂ and provides an optimal "off-state" for sensitive "turn-on" assay. In the present study, upon addition of melamine, the weak fluorescence system of CdTe@SiO₂-AuNPs is enhanced due to the strong interactions between the amino group of melamine and the gold nanoparticles via covalent bond, leading to the release of AuNPs from the surfaces of CdTe@SiO₂; thus, its fluorescence is restored. A "turn-on" fluorimetric method for the detection of melamine is proposed based on the restored fluorescence of the system. Under the optimal conditions, the fluorescence enhanced efficiency shows a linear function against the melamine concentrations ranging from 7.5 × 10⁻⁹ to 3.5 × 10⁻⁷ M (i.e., 1.0-44 ppb). The analytical sensitivity is improved by about 50%, and the detection limit is decreased by 5.0-fold, as compared with the analytical results using the CdTe-AuNPs system. Moreover, the proposed method was successfully applied to the determination of melamine in real samples with excellent recoveries in the range from 97.4 to 104.1%. Such a fluorescence energy transfer system between confined QDs and AuNPs may pave a new way for designing chemo/biosensing.

[Melamine related urinary calculus and acute renal failure in infants].

PubMed

Sun, Ning; Shen, Ying; Sun, Qiang; Li, Xu-ran; Jia, Li-qun; Zhang, Gui-ju; Zhang, Wei-ping; Chen, Zhi; Fan, Jian-feng; Jiang, Ye-ping; Feng, Dong-chuan; Zhang, Rui-feng; Zhu, Xiao-yu; Xiao, Hong-zhan

2008-11-01

To summarize clinical characteristics, diagnosis and treatment of infants with urinary calculus and acute renal failure developed after being fed with melamine tainted formula milk. Data of infant patients with urinary calculus and acute renal failure due to melamine tainted formula milk admitted to the Beijing Children's Hospital affiliated to the Capital Medical University and the Xuzhou Children's Hospital in 2008 were used to analyze the epidemiological characteristics, clinical manifestations, image features as well as effects of 4 types of therapies. All the 34 infants with urinary calculus were complicated with acute renal failure, their blood urea nitrogen (BUN) was (24.1 +/- 8.2) mmol/L and creatinine (Cr) was (384.2 +/- 201.2) micromol/L. The chemical analysis on the urinary calculus sampled from 14 of the infants showed that the calculus contained melamine and acidum uricum. The time needed for the four types of therapies for returning Cr to normal was (3.5 +/- 1.9) d for cystoscopy group, (2.7 +/- 1.1) d for lithotomy group, (3.8 +/- 2.3) d for dialysis group, and (2.7 +/- 1.6) d for medical treatment group, which had no statistically significant difference (P = 0.508). Renal failure of all the 34 infants was relieved within 1 to 7 days, averaging (3.0 +/- 1.8) d. Melamine tainted formula milk may cause urinary calculus and obstructive acute renal failure. It is suggested that firstly the patients with urinary calculus complicated with acute renal failure should be treated with dialysis or medication to correct electrolyte disturbances, in particular hyperkalemia, and then relieve the obstruction with available medical and surgical methods as soon as possible. It is observed that the short term prognosis is satisfactory.

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

NASA Astrophysics Data System (ADS)

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.

Acoustic Characterization of Grass-cover Ground

DTIC Science & Technology

2014-11-20

for noise and rever- beration control. Examples of porous media are cements , ceramics, rocks, building insulation, foams and soil. Characterizing the...To perform the calibration of the tube an absorbing material with known acoustic properties is used. A sample of Melamine foam , 5 cm thick was used...system was calibrated using materials with known acous- tic properties in order to confirm accurate measurement of the system. Melamine foam 5 cm (1.97 in

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

Treesearch

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...

Assessment of increased wet wood bonding for epoxy-bonded samples using a melamine-urea-formaldehyde priming agent

Treesearch

Jermal G. Chandler; Charles R. Frihart

2005-01-01

Is the hydroxymethylated resorcinol (HMR) primer unique or can a melamine- based primer also increase the wet wood strength of epoxy bonds? Although the exact reason for poor durability with some wood adhesives is not known, the HMR priming agent was found to facilitate durable bonds in most cases tested. A model of cell wall stabilization that is believed to be the...

Observations on Mildew Susceptibility of Painted Surfaces in Tropical Chamber Exposure

DTIC Science & Technology

1983-12-01

resins of iron oxide, red iron urea formaldehyde or oxide. blends of urea / melamine + modifiers, stabili- zers, wetting and sus- pension agents. MIL-E...type, modified or chromate yellow, molyb- with not less than 20% date orange, carbazole di- butylated melamine oxazine violet, yellow formaldehyde ...com- Pure short oil length Enamel, Modified Alkyd posed of cobalt, zinc, phthalic alkyd resin Camouflage, Lusterless and chromium oxides, and/ baking

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

Treesearch

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...

Facile synthesis of a two-tier hierarchical structured superhydrophobic-superoleophilic melamine sponge for rapid and efficient oil/water separation.

PubMed

Chen, Jiucun; You, Hui; Xu, Liqun; Li, Tianhao; Jiang, Xianquan; Li, Chang Ming

2017-11-15

Oil leakages often cause fatal disasters for environmental pollution but an efficient treatment of the oil spills is still very challenging. Sponge-substrates with superhydrophobicity and superoleophilicity have been attracted much attention for oil/water separation. In this study, an inexpensive commercial melamine sponge was chemically modified for the uses of oil spills treatment by oil/water separation. Inspiring from the superhydrophobic property of lotus leaf, pyrrole was polymerized by a simple vapor-phase deposition to encapsulate the raw melamine-formaldehyde (MF) sponge. The as-formed thin polypyrrole walls were utilized as reducing reagent to generate Ag nanoparticles on the capsuled sponge. Accordingly, a superhydrophobic melamine sponge with a two-tier hierarchical structure was achieved after fluorination, and this material was applied to absorb oil from water. The absorption capacity, absorption rate and recyclability were investigated. This superhydrophobic sponge exhibited an efficient and fast oil/water separation performance in complicated environment and could be applied in industrial production because of its low cost and simple fabrication procedure. This study presents a facile strategy for the fabrication of efficient oil sorbents based on a two-tier hierarchical structure, providing a novel means for the upgrading of engineered sorption materials. Copyright © 2017 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stagi, Luigi, E-mail: luigi.stagi@dsf.unica.it; Chiriu, Daniele; Carbonaro, Carlo M.

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 ofmore » {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.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, Vijay Kumar; Department of Chemical Technology, North Maharashtra University Jalgaon-425001; Division of Polymer Science and Engineering, National Chemical Laboratory, Pune-411 008

To achieve a high level of heavy metal adsorption, 1,1 Prime ,1 Double-Prime -(1,3,5-triazine-2,4,6-triyl)tris(3-(3-(triethoxysilyl)propyl)urea) (TTPU) was synthesized as a novel melamine precursor and incorporated on the silica surface of periodic mesoporous organosilica (PMO). The melamine modified PMOs (MPMOs) were synthesized under acidic conditions using TTPU, tetraethylorthosilicate (TEOS) and Pluronic P123 as a template and the modified PMOs were characterized using the relevant instrumental techniques. The characteristic materials were used as adsorbents for the adsorption of Fe(III) ions. Fe(III) adsorption studies revealed MPMO-7.5 to be a good absorbent with higher adsorption efficiency than other MPMOs. - Graphical Abstract: A new organosilicamore » precursor, TTPU, has been successfully synthesized and characterized to incorporate on the silica surface of periodic mesoporous organosilica (PMO). The melamine modified PMOs (MPMOs), in particular, the MPMO-7.5 was found to exhibit good adsorption efficiency for Fe(III). Highlights: Black-Right-Pointing-Pointer Synthesis of new melamine modified periodic mesoporous organosilicas (MPMOs). Black-Right-Pointing-Pointer A new organosilica precursor, TTPU, has been successfully synthesized for the MPMOs. Black-Right-Pointing-Pointer The MPMOs were characterized by the relevant instrumental techniques. Black-Right-Pointing-Pointer MPMO-7.5 exhibits higher adsorption efficiency for Fe(III) ions than other MPMOs.« less

Development of a mercury detection kit based on melamine-functionalized gold nanoparticles.

PubMed

Liu, Guoyan; Ren, Huipeng; Guan, Yuyu; Dai, Ronghua; Chai, Chunyan

2015-01-01

A fast and simple mercury detection kit was developed based on melamine-functionalized gold nanoparticles (GNPs). The detection kit contained reagent 1 (GNPs), reagent 2 (melanine), a reaction cuvette with four separated cells, a colorimetric card and a plastic pipette. The GNPs were prepared by a citrate reduction of HAuCl4. A proper amount of melamine was applied to functionalize the GNPs. The complex reaction took place in the present of Hg(2+) in the test samples, leading to the combination of Hg(2+) with the C=N group of melamine located on the surface of the GNPs. This reaction resulted in damage to the stability of colloid gold, and the aggregation of GNPs occurred. Different color changes (from claret-red to lilac, purple and plum) were displayed with different concentrations of Hg(2+) in the test samples. It was very easy and convenient to determine the amount of mercury ion by the naked eye. The advantages of this methodology are listed as follows: a short detecting time (within 10 min), a high specificity (no significant interference was indicated upon adding a certain amount of Cu(2+), Pb(2+), Zn(2+), Mg(2+), Cd(2+) and Fe(2+)), high sensitivity with a detection limit of 0.01 mg L(-1) , easy operation and practical on-site use.

Metal adatoms generated by the co-play of melamine assembly and subsequent CO adsorption.

PubMed

Wang, Li; Chen, Qiwei; Shi, Hong; Liu, Huihui; Ren, Xinguo; Wang, Bing; Wu, Kai; Shao, Xiang

2016-01-28

Molecular self-assembly films are expected to tailor the surface process by the periodic nanostructures and add-on functional groups. In this work, a molecular network of melamine with featured pores of subnanometer size is prepared on the Au(111) surface, and is found to be able to trap the gold adatoms and concomitant single vacancies generated under the impingement of CO molecules at room temperature. DFT calculations suggest that the strong CO-Au adatom interaction as well as the high adhesion of the Au adatom inside the melamine pore could well be the driving force behind such process. This study not only sheds light onto the interactions between gasses and the metal surface that is covered by molecular self-assembly films, but also provides a novel route to manipulate the monoatomic surface species which is of catalytic interest.

Number of Family Members, a New Influencing Factor to Affect the Risk of Melamine-Associated Urinary Stones

PubMed Central

LIU, Changjiang; LI, Hui; YANG, Kedi; YANG, Haixia

2013-01-01

Melamine is a new risk of urinary stones. Gansu province is a heavily affected area and has large population and underdeveloped economy. We hypothesized that number of family members and family income may play significant roles in the formation of urinary stones. A case-control study was performed among 190 infants. Results showed that the case group had less numbers of family members than the control (4.4 vs. 5.6, respectively). The multivariate logistic regression analysis indicated that number of family members was an independent influencing factor associated with urinary stones (OR, 0.606; 95% CI, 0.411–0.893; P = 0.011). Family income, however, did not exhibit a significant difference. Observed results suggested that number of family members was a new and significant influencing factor to affect the risk of melamine-associated urinary stones. PMID:23967433

[A cohort study of longer-term impact of melamine contaminated formula on infant health].

PubMed

Wang, Pei-xin; Li, Hong-tian; Wang, Lin-lin; Zhang, Long; Zhou, Yu-bo; Liu, Jian-meng

2013-10-15

To prospectively evaluate the health status of infants with exposure to melamine-contaminated milk formula prior to September 2008. The cohort study was conducted in an area close to the manufacturer of Sanlu dairy products. There were three groups (n = 47 each). In September 2008, the exposure group I included infants with exposure to melamine and a diagnosis of renal abnormalities, the exposure group IIhad exposure to melamine but there was no diagnosis of renal abnormalities and the non-exposure group had no exposure to melamine. The exposure II and non-exposure groups were matched with those of exposure group I by birthplaces, gender and date of birth ( ± 3 months). Kidney function tests (urea nitrogen, serum creatinine, uric acid, serum albumin, β2-microglobulin and cystatin C), liver function tests (alanine aminotransferase and aspartate aminotransferase), growth and development assessment and urinary system ultrasonography were implemented between November 2011 and June 2012. The analysis of covariance (least significant difference method) was performed to compare the differences of relevant variables among three groups. The urinary system ultrasonography showed that all abnormalities disappeared in exposure group I and all infants of another two groups had normal ultrasonography. There were statistically significant differences in serum uric acid and albumin of kidney function in exposure group I, exposure group II and non-exposure group ((344 ± 75) and (338 ± 98) and (282 ± 69) µmol/L , (47 ± 5) and (47 ± 6) and (43 ± 5) g/L, all P < 0.05) among three groups. However the differences in the remaining markers of kidney function, markers of liver function and Z scores of weight-for-age and height-for age were all statistically insignificant (all P > 0.05). Further pair-wise comparisons showed that the levels of serum uric acid and albumin in exposure group I were higher than those in non-exposure group (P = 0.001 and 0.010). And the levels of serum uric acid and albumin in exposure group II were also higher than those in non-exposure group (P = 0.003 and 0.005). All affected infants have recovered from kidney abnormalities. Early infant exposure to melamine-contaminated milk formula appears to have no obvious impact on liver function and growth. But its potential impact on kidney function should be further assessed.

Effectiveness of Flame Retardants in TufFoam.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abelow, Alexis Elizabeth; Nissen, April; Massey, Lee Taylor

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.

Dielectric Constant and Loss Data Part 2

DTIC Science & Technology

1975-12-01

fluoride, single crystal, Melamine - formaldehyde resins , Columbia Univ., P.R.-75 IV-21,22,112; V-8,88 Manganese-magnesium ferrite, Melamine GMG, IV-2i...butylperoxy) Urea - formaldehyde resins , IV-23 hexane, P.R.-197 U.S. Army Engineering Research and War Dept., Picatinny Arsenal, see Dev. Lab., Fort...IV.-36 irradiated, P.R,-161 "Bakelite" polyvinyl chloride- "Amplifilm," IV-14; V-74 acetate, see "Vinylites" Axiiliine- formaldehyde resins , IV-21

The melamine incident: implications for international food and feed safety.

PubMed

Gossner, Céline Marie-Elise; Schlundt, Jørgen; Ben Embarek, Peter; Hird, Susan; Lo-Fo-Wong, Danilo; Beltran, Jose Javier Ocampo; Teoh, Keng Ngee; Tritscher, Angelika

2009-12-01

A major food safety incident in China was made public in September 2008. Kidney and urinary tract effects, including kidney stones, affected about 300,000 Chinese infants and young children, with six reported deaths. Melamine had been deliberately added at milk-collecting stations to diluted raw milk ostensibly to boost its protein content. Subsequently, melamine has been detected in many milk and milk-containing products, as well as other food and feed products, which were also exported to many countries worldwide. The melamine event represents one of the largest deliberate food contamination incidents. We provide a description and analysis of this event to determine the global implications on food and feed safety. A series of factors, including the intentional character of the milk contamination, the young age of the population affected, the large number of potentially contaminated products, the global distribution of these products, and the delay in reporting led this event to take on unexpected proportions. This incident illustrated the complexity of international trade of food products and food ingredients that required immediate actions at international level. Managing food-safety events should be done internationally and early on as soon as multinational consequences are expected. Collaboration between food-safety authorities worldwide is needed to efficiently exchange information and to enable tracking and recalling of affected products to ensure food safety and to protect public health.

Preparation of magnetic melamine-formaldehyde resin and its application to extract nonsteroidal anti-inflammatory drugs.

PubMed

Xue, Shu-Wen; Li, Jing; Xu, Li

2017-05-01

Magnetic melamine-formaldehyde resin was prepared via water-in-oil emulsification approach by entrapping Fe 3 O 4 magnetic nanoparticles as the core. The preparation of the magnetic resin was optimized by investigating the amount of polyethylene glycol 20000 and Fe 3 O 4 nanoparticles, the concentration of the catalyst (hydrochloric acid), as well as the mechanical stirring rate. The prepared material was characteristic of excellent anion-exchange capacity, good water wettability, and proper magnetism. Its application was demonstrated by magnetic solid-phase extraction of nonsteroidal anti-inflammatory drugs coupled to high performance liquid chromatography-UV analysis. Under the optimal conditions, the proposed method showed broad linear range of 1-5000 ng mL -1 of milk and urine samples, satisfactory reproducibility with intra-day and inter-day relative standard deviations less than 12.4% and 9.7%, respectively, and low limits of detection of 0.2 ng mL -1 for the studied nonsteroidal anti-inflammatory drugs. The developed method was successfully used for the determination of the nonsteroidal anti-inflammatory drugs in spiked urine and milk samples. The magnetic melamine-formaldehyde resin was promising for the sample pretreatment of acidic analytes via anion-exchange interaction with convenient operation from complex sample matrix. Graphical abstract Magnetic solid-phase extraction based on melamine-formaldehyde resin.

The Melamine Incident: Implications for International Food and Feed Safety

PubMed Central

Gossner, Céline Marie-Elise; Schlundt, Jørgen; Ben Embarek, Peter; Hird, Susan; Lo-Fo-Wong, Danilo; Beltran, Jose Javier Ocampo; Teoh, Keng Ngee; Tritscher, Angelika

2009-01-01

Background A major food safety incident in China was made public in September 2008. Kidney and urinary tract effects, including kidney stones, affected about 300,000 Chinese infants and young children, with six reported deaths. Melamine had been deliberately added at milk-collecting stations to diluted raw milk ostensibly to boost its protein content. Subsequently, melamine has been detected in many milk and milk-containing products, as well as other food and feed products, which were also exported to many countries worldwide. Objectives The melamine event represents one of the largest deliberate food contamination incidents. We provide a description and analysis of this event to determine the global implications on food and feed safety. Discussions A series of factors, including the intentional character of the milk contamination, the young age of the population affected, the large number of potentially contaminated products, the global distribution of these products, and the delay in reporting led this event to take on unexpected proportions. This incident illustrated the complexity of international trade of food products and food ingredients that required immediate actions at international level. Conclusion Managing food-safety events should be done internationally and early on as soon as multinational consequences are expected. Collaboration between food-safety authorities worldwide is needed to efficiently exchange information and to enable tracking and recalling of affected products to ensure food safety and to protect public health. PMID:20049196

Melamine-tainted milk product-associated urinary stones in children.

PubMed

Wang, Zheng; Luo, Hong; Tu, Wenwei; Yang, Hui; Wong, Wilfred Hing-Sang; Wong, Wing-Tak; Yung, Ka-Fu; Zhou, Nan; Zhang, Jingti; Li, Xiaoqing; Wang, Zerong; Guo, Wenjun; Mu, Dezhi; Li, Fanghong; Mao, Meng; Lau, Yu-Lung

2011-08-01

An outbreak of urinary stones related to consumption of melamine-tainted milk products (MTMP) occurred in China in 2008. The aim of the present study was to evaluate such children to identify their clinical features and risk factors. Renal ultrasound was performed for 7328 children who presented to a Sichuan teaching hospital between 13 September and 15 October 2008 due to concern of such stones. Clinical data, family information, feeding history and urinary stones were analyzed. Of the 7328 children, 189 (2.58%) had ultrasound findings of urinary stones, and 51 were admitted. Age (mean ± SD) was 27.4 ± 25.5 months, and 101 were male and 88, female. The odds ratio (OR) for urinary stones for infants and young children (1-3 years) as compared to older children (>3 years), was 2.42 (95% confidence interval [CI], 1.64-3.56; P < 0.0001) and 1.95 (95%CI, 1.31-2.89; P < 0.0011), respectively. Independent risk factors associated with urinary stones included consumption of MTMP with melamine at > 5500 mg/kg (OR, 13.3; 95%CI, 6.8-26.1, P < 0.0001) as compared to that with melamine at < 200 mg/kg, and younger father (P = 0.0006). On logistic regression, the only risk factor associated with inpatient care was lower family income per person (OR, 4.4; 95%CI, 1.2-15.9, P = 0.02). Repeat ultrasound for 51 children at mean follow up of 15.3 ± 8.9 days found that 33 passed out all stones, which was associated with a larger number of smaller stones (P = 0.003). Urinary stones contained melamine and uric acid, but no cyanuric acid. MTMP-associated urinary stones were more frequent in young children and more severe in children from poorer families. © 2011 The Authors. Pediatrics International © 2011 Japan Pediatric Society.

Therapeutic-Ultrasound-Triggered Shape Memory of a Melamine-Enhanced Poly(vinyl alcohol) Physical Hydrogel.

PubMed

Li, Guo; Yan, Qiang; Xia, Hesheng; Zhao, Yue

2015-06-10

Therapeutic-ultrasound-triggered shape memory was demonstrated for the first time with a melamine-enhanced poly(vinyl alcohol) (PVA) physical hydrogel. The addition of a small amount of melamine (up to 1.5 wt %) in PVA results in a strong hydrogel due to the multiple H-bonding between the two constituents. A temporary shape of the hydrogel can be obtained by deformation of the hydrogel (∼65 wt % water) at room temperature, followed by fixation of the deformation by freezing/thawing the hydrogel under strain, which induces crystallization of PVA. We show that the ultrasound delivered by a commercially available device designed for the patient's pain relief could trigger the shape recovery process as a result of ultrasound-induced local heating in the hydrogel that melts the crystallized PVA cross-linking. This hydrogel is thus interesting for potential applications because it combines many desirable properties, being mechanically strong, biocompatible, and self-healable and displaying the shape memory capability triggered by a physiological stimulus.

Performance-Enhancing Methods for Au Film over Nanosphere Surface-Enhanced Raman Scattering Substrate and Melamine Detection Application

PubMed Central

Wang, Jun Feng; Wu, Xue Zhong; Xiao, Rui; Dong, Pei Tao; Wang, Chao Guang

2014-01-01

A new high-performance surface-enhanced Raman scattering (SERS) substrate with extremely high SERS activity was produced. This SERS substrate combines the advantages of Au film over nanosphere (AuFON) substrate and Ag nanoparticles (AgNPs). A three order enhancement of SERS was observed when Rhodamine 6G (R6G) was used as a probe molecule to compare the SERS effects of the new substrate and commonly used AuFON substrate. These new SERS substrates can detect R6G down to 1 nM. The new substrate was also utilized to detect melamine, and the limit of detection (LOD) is 1 ppb. A linear relationship was also observed between the SERS intensity at Raman peak 682 cm−1 and the logarithm of melamine concentrations ranging from 10 ppm to 1 ppb. This ultrasensitive SERS substrate is a promising tool for detecting trace chemical molecules because of its simple and effective fabrication procedure, high sensitivity and high reproducibility of the SERS effect. PMID:24886913

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

PubMed

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.

Prototype Aerogel Insulation for Melamine-Foam Substitute: Critical Space Station Express Rack Technology

NASA Technical Reports Server (NTRS)

Noever, David A.; Sibille, Laurent; Smith, David; Cronise, Raymond

1998-01-01

There is a current lack of environmentally acceptable foams to insulate Long-Duration Human Spaceflight Missions, including the experimental Express Rack for the Space Station. A recent 60-day manned test in a sealed chamber at Johnson Space Center (JSC) was nearly aborted, because of persistently high formaldehyde concentrations in the chamber. Subsequent investigation showed that the source was melamine foam (used extensively for acoustic insulation). The thermal and acoustic potential for melamine-foam substitutes is evaluated for scale-up to a silica-based foam and aerogel, which is environmentally benign for long duration space flight. These features will be discussed in reference to an aerogel prototype to: 1) assemble material strength data for various formulated aerogels, both silica and organic carbon aerogels; 2) assemble the aerogel into panels of mylar/vacuum-encapsulated rigid boards which can be molded in various shapes and rigidities; and 3) describe a process for space applications for formaldehyde-free, long duration thermal and acoustic insulators.

Preparation and oil absorption properties of magnetic melamine sponge

NASA Astrophysics Data System (ADS)

Lei, LUO; Jia-qi, HU; Na, LV

2017-12-01

The magnetic melamine sponge (MS-Fe3O4) with magnetic response and high hydrophobicity was fabricated by two-step method. First, the magnetic nano-particles were fixed on the skeleton of melamine sponge (MS) using 3-hydroxytyramine hydrochloride and 1-dodecanethiol, then hydrophobicity modified with octadecyltrichlorosilane (OTS). The structures and chemical compositions of MS and MS-Fe3O4 were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The wettability of the sample was obtained by using contact angle analysis system. MS-Fe3O4 endowed with outstanding selectivity and excellent oil absorption capacities, which can be widely used in absorbing various sorts of oil. The oil absorption capacities for crude oil, diesel oil, lubricating oil, soybean oil and peanut oil were 71g/g, 51g/g, 62g/g, 54g/g, 57g/g. In addition, MS-Fe3O4 showed excellent recyclability which can be forecasted as an ideal candidate for oil-water separation.

Performance-enhancing methods for Au film over nanosphere surface-enhanced Raman scattering substrate and melamine detection application.

PubMed

Wang, Jun Feng; Wu, Xue Zhong; Xiao, Rui; Dong, Pei Tao; Wang, Chao Guang

2014-01-01

A new high-performance surface-enhanced Raman scattering (SERS) substrate with extremely high SERS activity was produced. This SERS substrate combines the advantages of Au film over nanosphere (AuFON) substrate and Ag nanoparticles (AgNPs). A three order enhancement of SERS was observed when Rhodamine 6G (R6G) was used as a probe molecule to compare the SERS effects of the new substrate and commonly used AuFON substrate. These new SERS substrates can detect R6G down to 1 nM. The new substrate was also utilized to detect melamine, and the limit of detection (LOD) is 1 ppb. A linear relationship was also observed between the SERS intensity at Raman peak 682 cm(-1) and the logarithm of melamine concentrations ranging from 10 ppm to 1 ppb. This ultrasensitive SERS substrate is a promising tool for detecting trace chemical molecules because of its simple and effective fabrication procedure, high sensitivity and high reproducibility of the SERS effect.

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

NASA Astrophysics Data System (ADS)

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.

Exterior Weathering Durability of Some Leach-Resistant Fire-Retardant Treatments for Wood Shingles: A Five-Year Report.

DTIC Science & Technology

1981-07-01

phos. Code 29 impregnation phonium chloride (90%. in water) 12.5.5%, sodium hydroxide 150%. in water) 2.16%, urea 2.06/%, a liquid melamine 4.35...1.08%.. dicyandlamide 4.54%. (9) impregnation formaldehyde (37%) 4.32%. phosphoric acid 7.06%. water $3.0%. UOFP_2 Pressure Treating solution: Urea 1.44...sodium hydroxide (500o in water) 0.8710, urea 0.800o. a liquid melamine 1.74°o, water 91.570 o. 29 Pressure impregnation Treating solution: Tetrakis

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

PubMed

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

2010-12-01

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 not by as much as might have been anticipated, since 3% acetic acid gave migration values about double those obtained using water under the same time and temperature test conditions. In contrast, migration into the fatty food simulant olive oil was not detectable and at least 20-fold lower than with the aqueous food simulants. This was expected given the solubility properties of melamine and the characteristics of the melaware plastic. Migration levels into hot acidic beverages (apple juice, tomato juice, red-fruit tea and black coffee) were rather similar to the acetic acid simulant when the same time and temperature test conditions are used, e.g. 2 h at 70°C. However, migration levels into foods that were placed hot into melaware articles and then allowed to cool on standing were much lower (6-14 times lower) than if pre-heated food was placed into the articles and then maintained (artificially) at that high temperature in the same way that a controlled time-temperature test using simulants would be conducted. This very strong influence of time and especially temperature was manifest in the effects seen of microwave heating of food or beverage in the melaware articles. Here, despite the short duration of hot contact, migration levels were similar to simulants used for longer periods, e.g. 70°C for 2 h. This is rationalized in terms of the peak temperature achieved on microwave heating, which may exceed 70°C, counterbalancing the shorter time period held hot. There was also evidence that when using melaware utensils in boiling liquids, as for stovetop use of spatulas, the boiling action of circulating food/simulant can have an additional effect in promoting surface erosion, increasing the plastic decomposition and so elevating the melamine release.

Molecularly imprinted phloroglucinol-formaldehyde-melamine resin prepared in a deep eutectic solvent for selective recognition of clorprenaline and bambuterol in urine.

PubMed

Liang, Shiru; Yan, Hongyuan; Cao, Jiankun; Han, Yehong; Shen, Shigang; Bai, Ligai

2017-01-25

A new molecularly imprinted phloroglucinol-formaldehyde-melamine resin (MIPFMR) was synthesized in a deep eutectic solvent (DES) using phenylephrine as a dummy template. The MIPFMR was used as a solid phase extraction (SPE) sorbent for the selective isolation and recognition of clorprenaline (CLP) and bambuterol (BAM) in urine. Phloroglucinol and melamine were used as double functional monomers that introduced abundant hydrophilic groups (such as hydroxyl groups, imino groups, and ether linkages) into the MIPFMR, making it compatible with aqueous solvents. In addition, the formation of DES by combining the quaternary ammonium salt of choline chloride with ethylene glycol as a hydrogen bond donor was an environmentally safe alternative to toxic organic solvents such as chloroform and dimethylsulfoxide that are typically used in the preparation of most molecularly imprinted polymers (MIPs). Moreover, MIPFMR-based SPE of CLP and BAM in urine resulted in higher recoveries and purer extracts than those obtained by using other SPE materials (e.g., SCX, C 18 , HLB, and non-imprinted phloroglucinol-formaldehyde-melamine resin (NIPFMR)). The optimized MIPFMR-SPE-HPLC-UV method had good linearity (r 2  ≥ 0.9996) ranging from 15.0 to 3000.0 ng mL -1 for CLP and BAM, and the recoveries at three spiked levels ranged from 91.7% to 100.1% with RSDs ≤7.6%. The novel MIPFMR-SPE-HPLC-UV method is simple, selective, and accurate, and can be used for the determination of CLP and BAM in urine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Krüppel-like factor 5 associates with melamine-cyanurate crystal-induced nephritis in rats.

PubMed

Huang, Hsin-Lei; Yang, Wen-Ying; Pu, Hsiao-Fung; Tsai, Tung-Hu; Lin, Chi-Hung; Chen, Nien-Jung; Tarng, Der-Cherng

2013-10-01

Melamine and cyanuric acid (M/CA), when orally administered together to rats, can induce crystal formation within renal tubules and cause acute kidney injury. To investigate the pathomechanism of crystal-induced nephritis, melamine and/or cyanuric acid were administered to 3-week-old (young) and 8-week-old (adult) rats, respectively. Crystal formation, blood urea nitrogen elevation, tubular cell injury and macrophage infiltration were noted in rats fed with M/CA, but not in rats fed with vehicle, melamine or CA alone. These parameters were significantly higher in young rats than those in adult rats fed with M/CA 200 mg/kg body weight (BW) for 3 days. Krüppel-like factor 5 (KLF5) was expressed on distal tubule cells, especially when crystals deposited within the lumens. Both mRNA and protein levels were higher in young rats than those in adult rats fed with M/CA (200 mg/kg BW). KLF5 expression has been shown to modulate renal tissue cytokine production, and we found that proinflammatory cytokines like monocyte chemoattractant protein-1 and interlukin-6 were increased in kidney tissues of young rats fed with M/CA for 3 days. In contrast, interlukin-10, an anti-inflammatory cytokine, was upregulated in kidneys of adult rats fed with M/CA for 3 days. Crystals are prone to deposition in distal tubules of young rats fed with M/CA. M/CA Crystal-related nephritis might be induced by the KLF5 expression, which modulated macrophage recruitment and proinflammatory cytokine production, subsequently leading to renal tubular injury and interstitial inflammation.

Synthesis and characterizations of melamine-based epoxy resins.

PubMed

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.

Synthesis and Characterizations of Melamine-Based Epoxy Resins

PubMed Central

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

2013-01-01

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. PMID:24013372

Identification of the full anisotropic flow resistivity tensor for multiple glass wool and melamine foam samples.

PubMed

Van der Kelen, Christophe; Göransson, Peter

2013-12-01

The flow resistivity tensor, which is the inverse of the viscous permeability tensor, is one of the most important material properties for the acoustic performance of porous materials used in acoustic treatments. Due to the manufacturing processes involved, these porous materials are most often geometrically anisotropic on a microscopic scale, and for demanding applications, there is a need for improved characterization methods. This paper discusses recent refinements of a method for the identification of the anisotropic flow resistivity tensor. The inverse estimation is verified for three fictitious materials with different degrees of anisotropy. Measurements are performed on nine glass wool samples and seven melamine foam samples, and the anisotropic flow resistivity tensors obtained are validated by comparison to measurements performed on uni-directional cylindrical samples, extracted from the same, previously measured cubic samples. The variability of flow resistivity in the batch of material from which the glass wool is extracted is discussed. The results for the melamine foam suggest that there is a relation between the direction of highest flow resistivity, and the rise direction of the material.

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

NASA Astrophysics Data System (ADS)

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.

Characterization and Performance of Melamine Enhanced Urea Formaldehyde Resin for Bonding Southern Pine Particleboard

Treesearch

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

2011-01-01

Urea-formaldehyde resins modified by melamine were synthesized by four catalysts (H2SO4, HCl, H3PO4, and NaOH/NH4OH) with a F/U/M molar ratio of 1.38/1/0.074. Resin structure and thermal behavior were studied by 13C-NMR and DSC techniques. For H2SO4, HCl, and H3PO4 catalysts, resins were prepared by two stage pH adjustment: the first pH stage was set at 1.25 (H3PO4 pH...

OPERATION SANDSTONE. Nuclear Explosions. 1948. Scientific Director’s Report of Atomic Weapon Tests. Annex 11, Parts 1, 2, and 3. Thermal Effects and Decontamination Studies

DTIC Science & Technology

1948-06-30

formaldehyde 5 allyl resin 7 melamine resin 8 acrylic resin (lucite HC 201 H-3) 9 vinyl resin (Vinylite VS 131D K-3) 10 styrene resin (polystyrere J-7, mfgd...Chlorinated Rubber, CB.4L 24 Neoprene Melamine Resins 7 PoPysulfide Rubber,, IP.3 25 Acrylic Resins 8 Folysulfide Rubber, LP-2A 25A Vinyl Resins 9 Butyl...with the set of original samples. -- 5-- TABLE I. List of Sa,,ples SA2PLE I.O. MATERIAL 1 phenol formaldehyde 2 urea

Depth of penetration of a 785nm wavelength laser in food powders

NASA Astrophysics Data System (ADS)

Chao, Kuanglin; Dhakal, Sagar; Qin, Jianwei; Kim, Moon S.; Peng, Yankun; Schmidt, Walter F.

2015-05-01

Raman spectroscopy is a useful, rapid, and non-destructive method for both qualitative and quantitative evaluation of chemical composition. However it is important to measure the depth of penetration of the laser light to ensure that chemical particles at the very bottom of a sample volume is detected by Raman system. The aim of this study was to investigate the penetration depth of a 785nm laser (maximum power output 400mw) into three different food powders, namely dry milk powder, corn starch, and wheat flour. The food powders were layered in 5 depths between 1 and 5 mm overtop a Petri dish packed with melamine. Melamine was used as the subsurface reference material for measurement because melamine exhibits known and identifiable Raman spectral peaks. Analysis of the sample spectra for characteristics of melamine and characteristics of milk, starch and flour allowed determination of the effective penetration depth of the laser light in the samples. Three laser intensities (100, 200 and 300mw) were used to study the effect of laser intensity to depth of penetration. It was observed that 785nm laser source was able to easily penetrate through every point in all three food samples types at 1mm depth. However, the number of points that the laser could penetrate decreased with increasing depth of the food powder. ANOVA test was carried out to study the significant effect of laser intensity to depth of penetration. It was observed that laser intensity significantly influences the depth of penetration. The outcome of this study will be used in our next phase of study to detect different chemical contaminants in food powders and develop quantitative analysis models for detection of chemical contaminants.

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

PubMed Central

Sarafraz Yazdi, Ali; Raouf Yazdinezhad, Samaneh; Heidari, Tahereh

2014-01-01

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%). PMID:26644934

Explosive decomposition of a melamine-cyanuric acid supramolecular assembly for fabricating defect-rich nitrogen-doped carbon nanotubes with significantly promoted catalysis.

PubMed

Zhao, Zhongkui; Dai, Yitao; Ge, Guifang; Wang, Guiru

2015-05-26

A facile and scalable approach for fabricating structural defect-rich nitrogen-doped carbon nanotubes (MCSA-CNTs) through explosive decomposition of melamine-cyanuric acid supramolecular assembly is presented. In comparison to pristine carbon nanotubes, MCSA-CNT exhibits significantly enhanced catalytic performance in oxidant- and steam-free direct dehydrogenation of ethylbenzene, demonstrating the potential for metal-free clean and energy-saving styrene production. This finding also opens a new horizon for preparing highly-efficient carbocatalysts rich in structural defect sites for diverse transformations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexible and Compressible PEDOT:PSS@Melamine Conductive Sponge Prepared via One-Step Dip Coating as Piezoresistive Pressure Sensor for Human Motion Detection.

PubMed

Ding, Yichun; Yang, Jack; Tolle, Charles R; Zhu, Zhengtao

2018-05-09

Flexible and wearable pressure sensor may offer convenient, timely, and portable solutions to human motion detection, yet it is a challenge to develop cost-effective materials for pressure sensor with high compressibility and sensitivity. Herein, a cost-efficient and scalable approach is reported to prepare a highly flexible and compressible conductive sponge for piezoresistive pressure sensor. The conductive sponge, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)@melamine sponge (MS), is prepared by one-step dip coating the commercial melamine sponge (MS) in an aqueous dispersion of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Due to the interconnected porous structure of MS, the conductive PEDOT:PSS@MS has a high compressibility and a stable piezoresistive response at the compressive strain up to 80%, as well as good reproducibility over 1000 cycles. Thereafter, versatile pressure sensors fabricated using the conductive PEDOT:PSS@MS sponges are attached to the different parts of human body; the capabilities of these devices to detect a variety of human motions including speaking, finger bending, elbow bending, and walking are evaluated. Furthermore, prototype tactile sensory array based on these pressure sensors is demonstrated.

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

NASA Astrophysics Data System (ADS)

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.

Bulky melamine-based Zn-porphyrin tweezer as a CD probe of molecular chirality.

PubMed

Petrovic, Ana G; Vantomme, Ghislaine; Negrón-Abril, Yashira L; Lubian, Elisa; Saielli, Giacomo; Menegazzo, Ileana; Cordero, Roselynn; Proni, Gloria; Nakanishi, Koji; Carofiglio, Tommaso; Berova, Nina

2011-10-01

The transfer of chirality from a guest molecule to an achiral host is the subject of significant interest especially when, upon chiral induction, the chiroptical response of the host/guest complex can effectively report the absolute configuration (AC) of the guest. For more than a decade, dimeric metalloporphyrin hosts (tweezers) have been successfully applied as chirality probes for determination of the AC for a wide variety of chiral synthetic compounds and natural products. The objective of this study is to investigate the utility of a new class of melamine-bridged Zn-porphyrin tweezers as sensitive AC reporters. A combined approach based on an experimental CD analysis and a theoretical prediction of the prevailing interporphyrin helicity demonstrates that these tweezers display favorable properties for chiral recognition. Herein, we discuss the application of the melamine-bridged tweezer to the chiral recognition of a diverse set of chiral guests, such as 1,2-diamines, α-amino-esters and amides, secondary alcohols, and 1,2-amino-alcohols. The bulky periphery and the presence of a rigid porphyrin linkage lead, in some cases, to a more enhanced CD sensitivity than that reported earlier with other tweezers. Copyright © 2011 Wiley-Liss, Inc.

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

PubMed

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.

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

PubMed Central

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

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

NASA Astrophysics Data System (ADS)

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.

Surface Modification of Melamine-Formaldehyde (MF-R) Macroparticles in Complex Plasma

NASA Astrophysics Data System (ADS)

Semenov, A. V.; Pergament, A. L.; Scherbina, A. I.; Pikalev, A. A.

2018-04-01

The surface modification of melamine-formaldehyde (MF-R) macroparticles (4.12 ± 0.09 μm in diameter) in dc glow discharges in neon, argon, and an argon-oxygen mixture (90% Ar, 10% O2) was studied experimentally. The macroparticles were treated in the discharge plasma for 10, 20, 40, and 60 min. The macroparticles were placed in ordered plasma-dust structures and then extracted from them. The results of atomic force microscopy of the surface profile are presented. Quantitative data on destruction of the surface layer and aspects of its modification are discussed. The amount of substance removed from the particle surface for the exposure time was calculated using the fractal analysis method.

Adsorption of organic molecules on a porous polymer surface modified with the supramolecular structure of melamine-cyanuric acid

NASA Astrophysics Data System (ADS)

Gainullina, Yu. Yu.; Guskov, V. Yu.

2017-10-01

The adsorption of organic molecules on the surface of a porous polymeric sorbent modified with a mixed cyanuric acid-melamine supramolecular structure is studied. The parameters of thermodynamic adsorption are considered and the contributions from intermolecular interactions to the Helmholtz energy of adsorption are assessed. Analysis of the molar changes in internal energy and adsorption entropy shows that the supramolecular structure formed on the surface could not exhibit dimension effects, indicating there were no cavities. The contributions from nonspecific interactions to the Helmholtz energy of adsorption generally fall, while those of specific interactions increase, indicating an increase in the polarity of the sorbent surface.

One-step synthesis of nitrogen-doped carbon nanofibers from melamine over nickel alloy in a closed system

NASA Astrophysics Data System (ADS)

Kenzhin, Roman M.; Bauman, Yuri I.; Volodin, Alexander M.; Mishakov, Ilya V.; Vedyagin, Aleksey A.

2017-10-01

A novel approach to the synthesis of nitrogen-doped carbon nanofibers in a closed system at elevated pressure with the use of bulk Ni-Cr alloy as a catalyst precursor was proposed. Melamine was chosen as a substrate containing both carbon and nitrogen. Method of ferromagnetic resonance was applied for diagnostics of dispersed Ni particles appearance. The process of corrosion of a bulk alloy followed by formation of dispersed Ni particles catalyzing the growth of nitrogen-doped carbon nanofibers was found to take place at temperatures above 560 °C. The final content of nitrogen in obtained carbon nanofibers was about 10 at.%.

Drug resistance in trypanosomes; selective interference with trypanocidal action

PubMed Central

Williamson, J.

1959-01-01

Selective reversal of the trypanocidal action of carboxylated arsenicals by p-aminobenzoic acid and of melaminyl arsenicals and diamidines by melamine has been demonstrated in vivo and in vitro. The structural specificity of these reversal phenomena is high, and suggests preferential adsorption of the antagonist during a reversible primary drug fixation stage. Thiols antagonized neutral, carboxylated and melaminyl aromatic arsenicals equally, but not diamidines; p-aminobenzoic acid antagonism is specific for carboxylated arsenicals, and melamine antagonizes only the melaminyl arsenicals and the diamidines. These reversals reflect the pattern of crossresistance behaviour and suggest that cellular structures associated with a reversible stereospecific drug adsorption phase are modified during the development of resistance. PMID:13844960

3-Nitro-phenol-1,3,5-triazine-2,4,6-tri-amine (2/1).

PubMed

Sangeetha, V; Kanagathara, N; Chakkaravarthi, G; Marchewka, M K; Anbalagan, G

2013-06-01

The asymmetric unit of the title compound, C3H6N6·2C6H5NO3, contains one melamine and two 3-nitro-phenol mol-ecules. The mean planes of the 3-nitro-phenol mol-ecules are almost orthogonal to the plane of melamine, making dihedral angles of 82.77 (4) and 88.36 (5)°. In the crystal, mol-ecules 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 inter-actions [centroid-centroid distance = 3.9823 (9) Å].

Synthesis of crumpled nanosheets of polymeric carbon nitride from melamine cyanurate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dante, Roberto C., E-mail: rcdante@yahoo.com; Martín-Ramos, Pablo; Sánchez-Arévalo, F.M.

2013-05-01

Polymeric carbon nitride was synthesized by pyrolysis in nitrogen flux at different temperatures between 450 and 700 °C using melamine cyanurate as a reagent and sulfuric acid as a catalyst. The obtained carbon nitride consisted of curled nanosheets (650 °C), and globular particles (700 °C) with formula C₆N₇NHNH₂. The reaction yield of the catalyzed reaction was around the 15% for the sample treated at 700 °C, in a tapped crucible. The optical band gap of the polymer obtained at 700 °C is around 2.9 eV. The gap to the Fermi level is around 2 eV, considerably above the half ofmore » the band gap (due to electrons trapped in the gap), indicating that the polymer is probably a n-type semiconductor. - Graphical abstract: Transition from amorphous to crystalline carbon nitride, which is composed of globular particles and is a n-type wide band semiconductor. Highlights: • We synthetized carbon nitride using melamine cyanurate. • The reaction of carbon nitride formation is catalyzed by sulfuric acid. • The carbon nitride obtained at 700 °C is composed of globular particles. • The material obtained at 700 °C is a n-type semiconductor.« less

Melamine-Schiff base/manganese complex with denritic structure: An efficient catalyst for oxidation of alcohols and one-pot synthesis of nitriles.

PubMed

Kazemnejadi, Milad; Nikookar, Mahsa; Mohammadi, Mohammad; Shakeri, Alireza; Esmaeilpour, Mohsen

2018-05-18

Efficient and selective oxidation of alcohol to the corresponding carbonyl and/or nitrile was carried out by a new water-soluble melamine-based dendritic Mn(III) complex (Melamine-Mn (III)-Schiff base complex) in the presence of 2,4,6-trichloro-1,3,5-triazine (TCT) and O 2 at room temperature. Also, the oxidation of amine to the corresponding nitrile with high selectivity and conversion was performed at room temperature using the current method and high amounts of turnover frequencies (TOFs) were obtained for reactions. This system was also applicable for direct preparation of oxime through oxidation of alcohol. The catalyst was characterized by Fourier-transform infrared (FTIR), ultraviolet-visible (UV-Vis), thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), CHN and inductively coupled plasma (ICP) analyses. Also, oxidation/reduction behavior of the catalyst was studied by cyclic voltammetry (CV). Moreover, chemoselectivity of the catalyst was discussed with various combinations. The water-soluble catalyst could be recycled from the reaction mixture and reused for several times with a very low losing in efficiency. The recovered catalyst was also investigated with various analyses. Finally, gram scale preparation of nitrile was evaluated by present method. Copyright © 2018 Elsevier Inc. All rights reserved.

Effects of microwave heating on the migration of substances from melamine formaldehyde tableware.

PubMed

Poovarodom, Ngamtip; Junsrisuriyawong, Kansuda; Sangmahamad, Raweeporn; Tangmongkollert, Pattaree

2014-01-01

Melamine formaldehyde (MF) tableware, after undergoing repeated heating in a microwave oven for 1, 2, 3 or 5 min, was tested for migration into 3% (w/v) acetic acid, a food simulant. Overall migration (OM) consistently increased with an increasing number of heating/washing cycles, while formaldehyde was found at low concentrations or was not detectable. Unexpectedly, the 1-min series caused the most rapid increase in OM; the European Union regulatory limit of 10 mg dm(-2) was exceeded after 25 cycles. The number of cycles required to reach the OM limit rose to 29 and 67 for the 2- and 3-min series, respectively. Only 37 cycles were needed in the case of the 5-min series; however, the cumulative exposure time to microwave irradiation was relatively close to that of the 3-min series. These findings indicate that microwave heating affects the migration of MF in a significantly different manner as compared with conventional heating reported in previous studies. Fourier transform infrared spectroscopy (FTIR) spectra of MF after completing the microwave heating series show that the plastic was not fully cured, as evidenced by the absence of methylene linkages. The majority of migrants obtained from OM tests consisted of low molecular weight methylol melamine derivatives. The results indicate that microwave heating allowed demethylolation, addition and condensation reactions to occur, which was not the case when using conventional heating. This study demonstrates that microwave heating for 1-2 min in a repeated manner is of high concern in terms of consumer health. It was found that the service terms of melamine ware under microwave heating were drastically reduced, by more than 10-fold, as compared with the service terms under conventional heating. Hence, it is strongly recommended that manufacturers of MF articles provide instructions for use, e.g. "Do not use in microwave", which should be clearly visible to consumers and not easily detachable.

Insight into the localized surface plasmon resonance property of core-satellite nanostructures: Theoretical prediction and experimental validation.

PubMed

Song, Dongxing; Jing, Dengwei

2017-11-01

Regulation of the localized surface plasmon resonance (LSPR) of nanoparticles by changing the dielectric constant of the surrounding medium has been exploited in many practical applications. In this study, using Ag-nanodot-decorated SiO 2 nanoparticles (Ag-decorated SiO 2 NPs) with different solvents, we investigated the potential of using such core-satellite nanostructures as a liquid sensor for the determination of melamine. The dielectric constant effect of the surrounding medium on the LSPR property was given particular attention. It was found that colloids with water as solvent display a LSPR shift of 14nm, and this value was 18nm for ethanol. For colloids with methanol and glycol as solvents, the peak shifts are negligible. Finite-difference time-domain (FDTD) simulations were used to assign the LSPR peaks of Ag-decorated SiO 2 NPs and to monitor the effect of the substrate and solvent on the LSPR properties. In the calculations, the wavelength positions of the LSPR peaks for Ag-decorated SiO 2 NPs in various solvents were successfully predicted in the order methanol

Structural and vibrational spectral investigations of melaminium maleate monohydrate by FTIR, FT-Raman and quantum chemical calculations

NASA Astrophysics Data System (ADS)

Arjunan, V.; Kalaivani, M.; Marchewka, M. K.; Mohan, S.

2013-04-01

The structural investigations of the molecular complex of melamine with maleic acid, namely melaminium maleate monohydrate have been carried out by quantum chemical methods in addition to FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical studies were performed with DFT (B3LYP) method using 6-31G**, cc-pVDZ and 6-311++G** basis sets to determine the energy, structural and thermodynamic parameters of melaminium maleate monohydrate. The hydrogen atom from maleic acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak Osbnd H⋯O and Nsbnd H⋯O hydrogen bonds shows notable vibrational effects.

Evaluation of Renal Toxicity by Combination Exposure to Melamine and Cyanuric Acid in Male Sprague-Dawley Rats

PubMed Central

Son, Ji Yeon; Kang, Yoon Jong; Kim, Kyeong Seok; Kim, Tae Hyung; Lim, Sung Kwang; Lim, Hyun Jung; Jeong, Tae Cheon; Choi, Dal Woong; Chung, Kyu Hyuck; Lee, Byung Mu

2014-01-01

Melamine-induced nephrotoxicity is closely associated with crystal formation in the kidney caused by combined exposure to melamine (Mel) and cyanuric acid (CA). However, there are few dosage-finding studies for toxicological evaluation of chronic co-exposure to Mel and CA. The objective of this study was to investigate the possible mechanism by which a Mel and CA mixture lead to renal toxicity in rats. Mel and CA were co-administered to rats via oral gavage for 50 days. Nephrotoxicity was determined by measuring blood urea nitrogen (BUN) and serum creatinine (sCr) levels. Relative kidney weights were significantly increased in rats after co-exposure to Mel+CA (63/6.3 or 630/6.3 mg/kg) mixtures. BUN and sCr levels were significantly increased after Mel and CA co-exposure. Taken together, significant increase in KIM-1, NGAL, and calbindin levels were observed in the urine of rats exposed to Mel+CA (63/6.3 or 630/6.3 mg/kg) compared with the corresponding control group. Histological analysis revealed epithelial degeneration and necrotic cell death in the proximal tubules of the kidney after co-exposure to Mel+CA (63/6.3 or 630/6.3 mg/kg). Our data suggest that Mel-mediated renal toxicity may be influenced by CA concentrations in Mel-contaminated milk or foods. PMID:25071919

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing, Ling-Bao; Hou, Shu-Fen; Zhou, Jin

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 highmore » 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.« less

Structural and vibrational spectral investigations of melaminium maleate monohydrate by FTIR, FT-Raman and quantum chemical calculations.

PubMed

Arjunan, V; Kalaivani, M; Marchewka, M K; Mohan, S

2013-04-15

The structural investigations of the molecular complex of melamine with maleic acid, namely melaminium maleate monohydrate have been carried out by quantum chemical methods in addition to FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical studies were performed with DFT (B3LYP) method using 6-31G(**), cc-pVDZ and 6-311++G(**) basis sets to determine the energy, structural and thermodynamic parameters of melaminium maleate monohydrate. The hydrogen atom from maleic acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak OH···O and NH···O hydrogen bonds shows notable vibrational effects. Copyright © 2013 Elsevier B.V. All rights reserved.

In-situ phosphatizing coatings for aerospace, OEM and coil coating applications

NASA Astrophysics Data System (ADS)

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 dispersed into an ISPC and the performance of the final coating formulation is evaluated. Successful ISPCs formulated for multiple coating systems exhibited excellent adhesion, hardness and gloss, which supports their suitability as a chrome-free, single-step alternative for aerospace, original equipment manufacturing (OEM) and coil coating applications.

Presidential Green Chemistry Challenge: 2009 Greener Reaction Conditions Award

EPA Pesticide Factsheets

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.

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

PubMed

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.

Electrokinetic behavior of melamine-formaldehyde latex particles at moderate electrolyte concentration.

PubMed

Dahlsten, Per; Próchniak, Piotr; Kosmulski, Marek; Rosenholm, Jarl B

2009-11-15

The electrokinetic behavior of micrometer-sized melamine-formaldehyde latex particles in 10(-3)-10(-1)M monovalent electrolyte dispersions was investigated by electrophoresis and electroacoustics. Specific adsorption of the electrolytes was identified as a shift of the isoelectric point (pH(iep)) with an increased ionic strength. All salts had an equal dependence on the ionic strength. The pH(iep) was correlated with the anion sequence predicted by the hard-soft acid-base (HSAB) principle, Hofmeister series, and Born charging. The Born and the Hofmeister anion scale were successful in producing a systematic dependency of the isoelectric point (pH(iep)), particularly in high (10(-1)M) and low (10(-3)M) MF electrolyte dispersions. No clear trend could be found for the pH(iep) dependence on the anion HSAB scale.

Metabolic engineering of microbial competitive advantage for industrial fermentation processes.

PubMed

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.

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

PubMed Central

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

2017-01-01

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. PMID:29263605

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

Code of Federal Regulations, 2012 CFR

2012-04-01

... polymerization reaction control agent. Phthalic acid anhydride Do. Zinc stearate For use as lubricant. (c) The... extracted with the solvent or solvents characterizing the type of food and under the conditions of time and...

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

Code of Federal Regulations, 2011 CFR

2011-04-01

... be mixed with refined woodpulp and the mixture may contain other optional adjuvant substances which... temperature as determined from tables 1 and 2 of § 175.300(d) of this chapter, shall yield net chloroform...

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

Code of Federal Regulations, 2014 CFR

2014-04-01

... formaldehyde in water solution. (b) The resins may be mixed with refined woodpulp and the mixture may contain... chapter, shall yield net chloroform-soluble extractives not to exceed 0.5 milligram per square inch of...

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

Code of Federal Regulations, 2013 CFR

2013-04-01

... be mixed with refined woodpulp and the mixture may contain other optional adjuvant substances which... temperature as determined from tables 1 and 2 of § 175.300(d) of this chapter, shall yield net chloroform...

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

Code of Federal Regulations, 2010 CFR

2010-04-01

... be mixed with refined woodpulp and the mixture may contain other optional adjuvant substances which... temperature as determined from tables 1 and 2 of § 175.300(d) of this chapter, shall yield net chloroform...

Novel band gap-tunable K-Na co-doped graphitic carbon nitride prepared by molten salt method

NASA Astrophysics Data System (ADS)

Zhao, Jiannan; Ma, Lin; Wang, Haoying; Zhao, Yanfeng; Zhang, Jian; Hu, Shaozheng

2015-03-01

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), N2 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.

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

NASA Astrophysics Data System (ADS)

Xing, Ling-Bao; Hou, Shu-Fen; Zhou, Jin; Zhang, Jing-Li; Si, Weijiang; Dong, Yunhui; Zhuo, Shuping

2015-10-01

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-1 at 0.2 A g-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 Pb2+, Cu2+ and Cd2+. Moreover, the hydrophobic carbonized nitrogen-doped graphene aerogels (CNGAs) showed outstanding adsorption and recycling performance for the removal of various oils and organic solvents.

Insights into the relationship between CO₂ switchability and basicity: examples of melamine and its derivatives.

PubMed

Yin, Hongyao; Feng, Yujun; Liu, Hanbin; Mu, Meng; Fei, Chenhong

2014-08-26

Owing to its wide availability, nontoxicity, and low cost, CO2 working as a trigger to reversibly switch material properties, including polarity, ionic strength, hydrophilicity, viscosity, surface charge, and degree of polymerization or cross-linking, has attracted an increasing attention in recent years. However, a quantitative correlation between basicity of these materials and their CO2 switchability has been less documented though it is of great importance for fabricating switchable system. In this work, the "switch-on" and "switch-off" abilities of melamine and its amino-substituted derivatives by introducing and removing CO2 are studied, and then their quantitative relationship with basicity is established, so that performances of other organobases can be quantitatively predicted. These findings are beneficial for forecasting the CO2 stimuli-responsive behavior of other organobases and the design of CO2-switchable materials.

Synthesis of mesoporous poly(melamine-formaldehyde) particles by inverse emulsion polymerization.

PubMed

Schwarz, Dana; Weber, Jens

2017-07-15

Mesoporous poly(melamine-formaldehyde) (MF) particles with surface areas of up to 200m 2 g -1 were synthesized by an inverse emulsion polymerization using dodecane and Span80® as continuous phase. The finer details of the shape control (using emulsion techniques) and the porosity control (using silica nanoparticles as hard-template) are discussed. The impact of phase-separation processes on the observable porosity of the 20-200µm sized spherical particles is analysed by gas sorption methods and electron microscopy. The high density of amine and triazine functional groups in the porous MF particles make the material a promising adsorber for heavy metal ions and methylene blue. In a preliminary column experiment, the synthesized material exhibited a total capacity of 2.54mmol/g (≙ 812.4mg/g) for the adsorption of methylene blue. Copyright © 2017 Elsevier Inc. All rights reserved.

From melamine sponge towards 3D sulfur-doping carbon nitride as metal-free electrocatalysts for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Xu, Jingjing; Li, Bin; Li, Songmei; Liu, Jianhua

2017-07-01

Development of new and efficient metal-free electrocatalysts for replacing Pt to improve the sluggish kinetics of oxygen reduction reaction (ORR) is of great importance to emerging renewable energy technologies such as metal-air batteries and polymer electrolyte fuel cells. Herein, 3D sulfur-doping carbon nitride (S-CN) as a novel metal-free ORR electrocatalyst was synthesized by exploiting commercial melamine sponge as raw material. The sulfur atoms were doping on CN networks uniformly through numerous S-C bonds which can provide additional active sites. And it was found that the S-CN exhibited high catalytic activity for ORR in term of more positive onset potential, higher electron transfer number and higher cathodic density. This work provides a novel choice of metal-free ORR electrocatalysts and highlights the importance of sulfur-doping CN in metal-free ORR electrocatalysts.

A Unique 3D Nitrogen-Doped Carbon Composite as High-Performance Oxygen Reduction Catalyst

PubMed Central

Karunagaran, Ramesh; Tung, Tran Thanh; Tran, Diana; Coghlan, Campbell; Doonan, Christian

2017-01-01

The synthesis and properties of an oxygen reduction catalyst based on a unique 3-dimensional (3D) nitrogen doped (N-doped) carbon composite are described. The composite material is synthesised via a two-step hydrothermal and pyrolysis method using bio-source low-cost materials of galactose and melamine. Firstly, the use of iron salts and galactose to hydrothermally produceiron oxide (Fe2O3) magnetic nanoparticle clusters embedded carbon spheres. Secondly, magnetic nanoparticles diffused out of the carbon sphere when pyrolysed in the presence of melamine as nitrogen precursor. Interestingly, many of these nanoparticles, as catalyst-grown carbon nanotubes (CNTs), resulted in the formation of N-doped CNTs and N-doped carbon spheres under the decomposition of carbon and a nitrogen environment. The composite material consists of integrated N-doped carbon microspheres and CNTs show high ORR activity through a predominantly four-electron pathway. PMID:28792432

Intercalation of sulfonated melamine formaldehyde polycondensates into a hydrocalumite LDH structure

NASA Astrophysics Data System (ADS)

von Hoessle, F.; Plank, J.; Leroux, F.

2015-05-01

A series of sulfonated melamine formaldehyde (SMF) polycondensates possessing different anionic charge amounts and molecular weights was synthesized and incorporated into a hydrocalumite type layered double hydroxide structure using the rehydration method. For this purpose, tricalcium aluminate was dispersed in water and hydrated in the presence of these polymers. Defined inorganic-organic hybrid materials were obtained as reaction products. All SMF polymers tested intercalated readily into the hydrocalumite structure, independent of their different molecular weights (chain lengths) and anionic charge amounts. X-ray diffraction revealed typical patterns for weakly ordered, highly polymer loaded LDH materials which was confirmed via elemental analysis and thermogravimetry. IR spectroscopy suggests that the SMF polymers are interleaved between the [Ca2Al(OH)6]+ main sheets via electrostatic interaction, and that no chemical bond between the host matrix and the guest anion is formed. The SMF polymers well ensconced within the LDH structure exhibit significantly slower thermal degradation.

Biocompatible 3D SERS substrate for trace detection of amino acids and melamine

NASA Astrophysics Data System (ADS)

Satheeshkumar, Elumalai; Karuppaiya, Palaniyandi; Sivashanmugan, Kundan; Chao, Wei-Ting; Tsay, Hsin-Sheng; Yoshimura, Masahiro

2017-06-01

A novel, low-cost and biocompatible three-dimensional (3D) substrate for surface-enhanced Raman spectroscopy (SERS) is fabricated using gold nanoparticles (AuNPs) loaded on cellulose paper for detection of amino acids and melamine. Dysosma pleiantha rhizome (Dp-Rhi) capped AuNPs (Dp-Rhi_AuNPs) were prepared by in situ using aqueous extract of Dp-Rhi and in situ functionalized Dp-Rhi on AuNPs surface was verified by Fourier transform infrared spectroscopy and zeta potentials analysis shows a negative (- 18.4 mV) surface charges, which confirm that presence of Dp-Rhi on AuNPs. The biocompatibility of Dp-Rhi_AuNPs is also examined by cell viability of FaDu cells using MTS assay and compared to control group. In conclusion, the SERS performance of AuNPs@cellulose paper substrates were systematically demonstrated and examined with different excitation wavelengths (i.e. 532, 632.8 and 785 nm lasers) and the as-prepared 3D substrates provided an enhancement factor approaching 7 orders of magnitude compared with conventional Raman intensity using para-nitrothiophenol (p-NTP), para-aminothiophenol (p-ATP) and para-mercaptobenzoic acid (p-MBA) as probe molecules. The strong electromagnetic effect was generated at the interface of AuNPs and pre-treated roughened cellulose paper is also investigated by simulation in which the formation of possible Raman hot-spot zone in fiber-like microstructure of cellulose paper decorated with AuNPs. Notably, with optimized condition of as-prepared 3D AuNPs@cellulose paper is highly sensitive in the SERS detection of aqueous tyrosine (10- 10 M) and melamine (10- 9 M).

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

PubMed

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.

Gold sputtered Blu-Ray disks as novel and cost effective sensors for surface enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

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

2015-03-01

Surface Enhanced Raman spectroscopy (SERS) offers sensitive and non-invasive detection of a variety of compounds as well as unparalleled information for establishing the molecular identity of both inorganic and organic compounds, not only in biological fluids but in all other aqueous and non-aqueous media. The localized hotspots produced through SERS at the solution/nanostructure interface of clustered gold or silver nano-particles enables detection levels of parts per trillion. Recent developments in advanced fabrication methods have enabled the manufacture of SERS substrates with repeatable surface nanostructures which provide reproducible quantitative analysis, historically a weakness of the SERS technique. In this paper we describe the novel use of gold sputtered Blu-Ray surfaces as SERS substrates. Blu-Ray disks provide ideal surfaces of SERS substrates with their repeatable and regular nano-gratings. We show that the unique surface features and composition of the recording surface enables the formation of gold nano-islands with nanogaps, simply through gold sputtering, and relate this to a 600 fold signal increase of the melamine Raman signal in aqueous solutions and detection to 68 ppb. Melamine is a triazine compound and appears not only as environmental contaminant in environmental groundwater but also as an adulterant in foods due to its high nitrogen content. We have shown significant SERS signal enhancements for spectra of melamine using gold-sputtered Blu-Ray disk surfaces, with reproducibility of 12%. Blu-Ray disks have a unique combination of design, surface features and composition of the recording surface which makes them ideal for preparation of SERS substrates by gold sputter-coating.

Facile synthesis of nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite with enhanced photocatalytic performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiangpeng; Li, Changqing; Cong, Jingkun

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{submore » 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.« less

In situ construction of g-C3N4/TiO2 heterojunction films with enhanced photocatalytic activity over magnetic-driven rotating frame

NASA Astrophysics Data System (ADS)

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.

Identification of pesticide transformation products in agricultural soils using liquid chromatography/quadrupole-time-of-flight mass spectrometry.

PubMed

Padilla-Sánchez, Juan A; Michael Thurman, E; Plaza-Bolaños, Patricia; Ferrer, Imma

2012-05-15

A study of pesticide transformation products (TPs) was carried out in soils of agricultural areas working under integrated pest management programs (IPMs). Bupirimate and cyromazine were the pesticides detected in soils after an initial pre-screening. The aim of this work was the identification of relevant TPs of these two pesticides. Soil samples were extracted by pressurized liquid extraction (PLE), using a mixture of ethyl acetate/methanol (3:1, v/v), and analyzed by ultra-high-pressure liquid chromatography coupled to hybrid quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS). For confirmation purposes, tandem mass spectrometry (MS(2) ) experiments were carried out using QTOF-MS, obtaining specific fragment structures of the pesticides and their degradates. Retention times and exact masses of the protonated molecules were used for the identification of the pesticides bupirimate (m/z 317.1642) and cyromazine (m/z 167.1040) and their respective TPs, namely ethirimol (m/z 210.1601) and melamine (m/z 127.0727). A novel strategy using pseudo-MS(3) experiments was developed to confirm the structure of bupirimate TP (ethirimol). This strategy consists of generating the particular TP in the ion source, via collision-induced fragmentation, and then performing MS/MS to the fragment ion formed in-source. Ethirimol and melamine were identified as degradation products of bupirimate and cyromazine, respectively. The study was applied to the analysis of 15 agricultural soil samples finding bupirimate and ethirimol in seven samples, cyromazine in one sample and melamine in four samples. Copyright © 2012 John Wiley & Sons, Ltd.

Effects of seven chemicals on DNA damage in the rat urinary bladder: a comet assay study.

PubMed

Wada, Kunio; Yoshida, Toshinori; Takahashi, Naofumi; Matsumoto, Kyomu

2014-07-15

The in vivo comet assay has been used for the evaluation of DNA damage and repair in various tissues of rodents. However, it can give false-positive results due to non-specific DNA damage associated with cell death. In this study, we examined whether the in vivo comet assay can distinguish between genotoxic and non-genotoxic DNA damage in urinary bladder cells, by using the following seven chemicals related to urinary bladder carcinogenesis in rodents: N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN), glycidol, 2,2-bis(bromomethyl)-1,3-propanediol (BMP), 2-nitroanisole (2-NA), benzyl isothiocyanate (BITC), uracil, and melamine. BBN, glycidol, BMP, and 2-NA are known to be Ames test-positive and they are expected to produce DNA damage in the absence of cytotoxicity. BITC, uracil, and melamine are Ames test-negative with metabolic activation but have the potential to induce non-specific DNA damage due to cytotoxicity. The test chemicals were administered orally to male Sprague-Dawley rats (five per group) for each of two consecutive days. Urinary bladders were sampled 3h after the second administration and urothelial cells were analyzed by the comet assay and subjected to histopathological examination to evaluate cytotoxicity. In the urinary bladders of rats treated with BBN, glycidol, and BMP, DNA damage was detected. In contrast, 2-NA induced neither DNA damage nor cytotoxicity. The non-genotoxic chemicals (BITC, uracil, and melamine) did not induce DNA damage in the urinary bladders under conditions where some histopathological changes were observed. The results indicate that the comet assay could distinguish between genotoxic and non-genotoxic chemicals and that no false-positive responses were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Junkuo, E-mail: jkgao@zstu.edu.cn; Wang, Jiangpeng; Qian, Xuefeng

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 visiblemore » 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.« less

Characteristics of a Power Line Used as a VLF Antenna.

DTIC Science & Technology

1982-05-01

were glass melamine . Assemblies of 12 layers were fabricated at El Segundo, CA and shipped by air to Tromso, Norway for final assembly of the full 120...sciences, applied electronics, semiconductor crystal and device physics, radiometric Imaging; millimeter-wave and microwave technology. Information

Application of liquefied wood as a new particle board adhesive system.

PubMed

Kunaver, Matjaz; Medved, Sergej; Cuk, Natasa; Jasiukaityte, Edita; Poljansek, Ida; Strnad, Tatjana

2010-02-01

Different types of southern European hardwoods and softwoods were subjected to a liquefaction process with glycerol/diethylene glycol. The liquefied spruce wood was reacted in a condensation reaction in the hot press with different melamine-formaldehyde and melamine-urea-formaldehyde resin precursors and used as adhesives for wood particle boards. The mechanical properties of these particle boards and the determination of formaldehyde release, proved that addition of 50% of the liquefied wood to such resin precursors caused the product to meet the European standard quality demands for particle boards. Up to 40% reduction of the formaldehyde emission was achieved. The temperature of the press unit was lowered from 180 degrees C to 160 degrees C with no significant influence on the mechanical properties. On the basis of the presented results it was possible to conclude that liquefied wood can be used as substitute for synthetic resin precursors in adhesives that are used for the particle board production.

Investigation of melamine derived quaternary as ammonium salt potential shale inhibitor

NASA Astrophysics Data System (ADS)

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.

Performance of carbon material derived from starch mixed with flame retardant as electrochemical capacitor

NASA Astrophysics Data System (ADS)

Tsubota, Toshiki; Morita, Masaki; Murakami, Naoya; Ohno, Teruhisa

2014-12-01

Carbon materials derived from starch with an added flame retardant, such as melamine polyphosphate, melamine sulfate, guanylurea phosphate, or guanidine phosphate, were synthesized for investigating the performance as the electrode of an electrochemical capacitor. The yield after the heat treatment of the carbonization reaction increased by the addition of these flame retardants up to 800 °C. Although both the specific surface area and electrical resistivity are almost independent of the addition of the flame retardants, the capacitance values are improved with the addition of the flame retardants. The nitrogen atoms derived from the flame retardants are introduced to some extent into the synthesized carbon material. Moreover, the phosphorous atoms or the sulfur atoms derived from the flame retardants are doped into the synthesized carbon material. The method applied in this study, that is, the addition of flame retardants before the carbonization process can be used for the doping of the hetero atom such as N, P and S into the carbon material.

Waterborne Colloidal Polymer/Silica Hybrid Dispersions and Their Assembly into Mesoporous Poly(melamine-formaldehyde) Xerogels.

PubMed

Schwarz, Dana; Weber, Jens

2015-08-04

The acid-catalyzed polycondensation of oligo(melamine-formaldehyde) in aqueous phase and in the presence of silica nanoparticles leads to a stable dispersion of coexisting silica and polymer nanoparticles. The dispersion can be processed into mesoporous xerogels (SBET ≈ 200 m(2) g(-1)), whose porosity can be enhanced by etching of silica up to specific surface areas of >400 m(2) g(-1). The formation mechanism and the characteristics of the hybrid dispersion are crucial to the materials derived from it and analyzed in detail using a variety of experimental techniques (electron and force microscopy, light and X-ray scattering, ultracentrifugation, and spectroscopy). The transformation of the dispersion into xerogels by electrostatic destabilization is described. Furthermore, the obtained materials are characterized with regard to their porosity and morphology using microscopy and porosimetry. The impact of selected synthesis parameters on the obtained properties is discussed, and it was found (most interestingly) that stable porosity was only observed if silica nanoparticles were present within the dispersion.

Is it possible to screen for milk or whey protein adulteration with melamine, urea and ammonium sulphate, combining Kjeldahl and classical spectrophotometric methods?

PubMed

Finete, Virgínia de Lourdes Mendes; Gouvêa, Marcos Martins; Marques, Flávia Ferreira de Carvalho; Netto, Annibal Duarte Pereira

2013-12-15

The Kjeldahl method and four classic spectrophotometric methods (Biuret, Lowry, Bradford and Markwell) were applied to evaluate the protein content of samples of UHT whole milk deliberately adulterated with melamine, ammonium sulphate or urea, which can be used to defraud milk protein and whey contents. Compared with the Kjeldahl method, the response of the spectrophotometric methods was unaffected by the addition of the nitrogen compounds to milk or whey. The methods of Bradford and Markwell were most robust and did not exhibit interference subject to composition. However, the simultaneous interpretation of results obtained using these methods with those obtained using the Kjeldahl method indicated the addition of nitrogen-rich compounds to milk and/or whey. Therefore, this work suggests a combination of results of Kjeldahl and spectrophotometric methods should be used to screen for milk adulteration by these compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

PubMed

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.

Single-Drop Raman Imaging Exposes the Trace Contaminants in Milk.

PubMed

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.

Qualitative and quantitative analysis of milk for the detection of adulteration by Laser Induced Breakdown Spectroscopy (LIBS).

PubMed

Moncayo, S; Manzoor, S; Rosales, J D; Anzano, J; Caceres, J O

2017-10-01

The present work focuses on the development of a fast and cost effective method based on Laser Induced Breakdown Spectroscopy (LIBS) to the quality control, traceability and detection of adulteration in milk. Two adulteration cases have been studied; a qualitative analysis for the discrimination between different milk blends and quantification of melamine in adulterated toddler milk powder. Principal Component Analysis (PCA) and neural networks (NN) have been used to analyze LIBS spectra obtaining a correct classification rate of 98% with a 100% of robustness. For the quantification of melamine, two methodologies have been developed; univariate analysis using CN emission band and multivariate calibration NN model obtaining correlation coefficient (R 2 ) values of 0.982 and 0.999 respectively. The results of the use of LIBS technique coupled with chemometric analysis are discussed in terms of its potential use in the food industry to perform the quality control of this dairy product. Copyright © 2017 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Torlakoglu, A.; Gueclue, G.

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. Themore » 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.« less

An investigation of FT-Raman spectroscopy for quantification of additives to milk

USDA-ARS?s Scientific Manuscript database

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...

78 FR 34820 - Formaldehyde Emissions Standards for Composite Wood Products

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-10

... and paper product coatings. It is a by-product of combustion and certain other natural processes..., dryers, formers, board coolers, and presses) at PCWP facilities. In 2004, EPA determined that unit risk... (e.g., vinyl, paper, melamine, polyethylene) and coatings (e.g., acrylate, acrylic, polyurethane...

Development of a Raman chemical imaging detection method for authenticating skim milk powder

USDA-ARS?s Scientific Manuscript database

This research demonstrated that Raman chemical imaging coupled with a simple image classification algorithm can be used to detect multiple chemical adulterants in skim milk powder. Ammonium sulfate, dicyandiamide, melamine, and urea were mixed into the milk powder as chemical adulterants in the conc...

Simultaneous detection of multiple adulterants in dry milk using macro-scale Raman chemical imaging

USDA-ARS?s Scientific Manuscript database

The potential of Raman chemical imaging for simultaneously detecting multiple adulterants in milk powder was investigated. Potential chemical adulterants, including ammonium sulfate, dicyandiamide, melamine, and urea, were mixed together into skim dry milk in the concentration range of 0.1–5.0% for ...

The cost-effective synthesis of furan- and thienyl-based microporous polyaminals for adsorption of gases and organic vapors.

PubMed

Li, Guiyang; Zhang, Biao; Yan, Jun; Wang, Zhonggang

2016-01-21

This work reveals that furfural and 2-thenaldehyde can readily react with melamine via "one-step" polycondensation to yield hyper-cross-linked sulfur-, nitrogen- and oxygen-rich microporous polyaminals with promising applications in adsorption of gases and toxic organic vapors.

Laser machining wood composites

Treesearch

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...

40 CFR 721.10136 - 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl...

Code of Federal Regulations, 2010 CFR

2010-07-01

...-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl)melamine (generic). 721.10136 Section 721.10136... 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl... substance identified generically as 2-propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products...

40 CFR 721.10136 - 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl...

Code of Federal Regulations, 2011 CFR

2011-07-01

...-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl)melamine (generic). 721.10136 Section 721.10136... 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl... substance identified generically as 2-propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products...

Effect of different catalysts on urea-formaldehyde resin synthesis

Treesearch

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...

Study on Raman spectral imaging method for simultaneous estimation of ingredients concentration in food powder

USDA-ARS?s Scientific Manuscript database

This study investigated the potential of point scan Raman spectral imaging method for estimation of different ingredients and chemical contaminant concentration in food powder. Food powder sample was prepared by mixing sugar, vanillin, melamine and non-dairy cream at 5 different concentrations in a ...

Melamine-assisted one-pot synthesis of hierarchical nitrogen-doped carbon@MoS2 nanowalled core-shell microspheres and their enhanced Li-storage performances

NASA Astrophysics Data System (ADS)

Sun, Fugen; Wei, Yanju; Chen, Jianzhuang; Long, Donghui; Ling, Licheng; Li, Yongsheng; Shi, Jianlin

2015-07-01

A facile and scalable one-pot approach has been developed to synthesize carbon@MoS2 core-shell microspheres by a hydrothermal method, which involves the fast formation of melamine-resorcinol-formaldehyde polymeric microspheres in situ, followed by direct growth of the MoS2 nanowalls on them. The results give unequivocal proof that melamine could be the key to forming the core-shell microspherical morphology, and the contents of MoS2 shells can be easily tuned by initial ratios of the precursors. After a simple heat treatment, the obtained carbon@MoS2 microspheres simultaneously integrate the nitrogen-doped carbon cores and the hierarchical shells which consist of few-layered MoS2 nanowalls with an expanded interlayer spacing. Their unique architectures are favourable for high electronic/ionic conductivity and accommodate volume strain during the electrochemical reaction of the MoS2 anodes in lithium-ion batteries. Thus, a very high reversibility capacity of 771 mA h g-1 at 100 mA g-1 after 100 cycles, and a rate capacity of 598 mA h g-1 at 2000 mA g-1 could be achieved for the carbon@MoS2 core-shell microspheres with the optimal composition. Furthermore, a thin carbon coating on the carbon@MoS2 microspheres could further increase the reversible capacity to 856 mA h g-1 after 100 cycles at 100 mA g-1. These encouraging results suggest that such a facile and efficient protocol can provide a new pathway to produce hierarchical core-shell microspheres which integrate the structural, morphological and compositional design rationales for advanced lithium-ion batteries.A facile and scalable one-pot approach has been developed to synthesize carbon@MoS2 core-shell microspheres by a hydrothermal method, which involves the fast formation of melamine-resorcinol-formaldehyde polymeric microspheres in situ, followed by direct growth of the MoS2 nanowalls on them. The results give unequivocal proof that melamine could be the key to forming the core-shell microspherical morphology, and the contents of MoS2 shells can be easily tuned by initial ratios of the precursors. After a simple heat treatment, the obtained carbon@MoS2 microspheres simultaneously integrate the nitrogen-doped carbon cores and the hierarchical shells which consist of few-layered MoS2 nanowalls with an expanded interlayer spacing. Their unique architectures are favourable for high electronic/ionic conductivity and accommodate volume strain during the electrochemical reaction of the MoS2 anodes in lithium-ion batteries. Thus, a very high reversibility capacity of 771 mA h g-1 at 100 mA g-1 after 100 cycles, and a rate capacity of 598 mA h g-1 at 2000 mA g-1 could be achieved for the carbon@MoS2 core-shell microspheres with the optimal composition. Furthermore, a thin carbon coating on the carbon@MoS2 microspheres could further increase the reversible capacity to 856 mA h g-1 after 100 cycles at 100 mA g-1. These encouraging results suggest that such a facile and efficient protocol can provide a new pathway to produce hierarchical core-shell microspheres which integrate the structural, morphological and compositional design rationales for advanced lithium-ion batteries. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03708e

Identification and evaluation of composition in food powder using point-scan Raman spectral imaging

USDA-ARS?s Scientific Manuscript database

This study used Raman spectral imaging coupled with self-modeling mixture analysis (SMA) for identification of three components mixed into a complex food powder mixture. Vanillin, melamine, and sugar were mixed together at 10 different concentration levels (spanning 1% to 10%, w/w) into powdered non...

Development of a Raman chemical image detection algorithm for authenticating dry milk

USDA-ARS?s Scientific Manuscript database

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 la...

Detecting multiple adulterants in dry milk using Raman chemical imaging

USDA-ARS?s Scientific Manuscript database

A Raman chemical imaging method was developed for detecting the presence of multiple chemical adulterants in dry milk powder. Four chemicals (ammonium sulfate, dicyandiamide, melamine, and urea) were added in equal concentrations, between 0.1% and 5.0%, to nonfat dry milk. An area of 25×25 mm2 for e...

Rocket and Missile Container Engineering Guide

DTIC Science & Technology

1982-01-01

impregnated with urea - formaldehyde and melamine - formaldehyde resins , found that a high degree of fungous resistance was imparted to the cotton...34 Phenol-aniline- formaldehyde Resorcinol- formaldehyde Urea - formaldehydes Urea -formaldehydeh Protein- formaldehydes Zein- formaldehyde ("Vicara") Casein...Practically, any cush- ioning material can be made resistant to fungi. The treatment usually involves impregnation

Raman spectral imaging for quantitative contaminant evaluation in skim milk powder

USDA-ARS?s Scientific Manuscript database

This study uses a point-scan Raman spectral imaging system for quantitative detection of melamine in milk powder. A sample depth of 2 mm and corresponding laser intensity of 200 mW were selected after evaluating the penetration of a 785 nm laser through milk powder. Horizontal and vertical spatial r...

Materials Evaluated as Potential Soil Stabilizers

DTIC Science & Technology

1977-09-01

resin systems including melamines , furfurals, formaldehydes , ureas , sili- cates, acrylamides, vinyls, styrenes, epoxies, and acrylates. Special...CEMENT .. .................. A60 CATEGORY: LIME .. .. ................. A130 CATEGORY: RESIN . .. ................. A155 CATEGORY: SALT...attention was given to calcium acrylate, which had been found unique in developing high strength in very wet soils. This polymer resin was studied extensively

Effect of resin type on properties of steam-press-cured flakeboards

Treesearch

Chung-Yun Hse; Robert L. Geimer; W. Ernest Hsu; R.C. Tang

1995-01-01

Six potentially important wood adhesives for gluing southern pine and white oak flakeboards were evaluated for their performances in steam-injection pressing and conventional platen pressing. Of the six resins tested, polyisocyanate resin performed well in both steam injection and conventional platen pressings. Phenol-fonnaldehyde (PF) and melamine urea-fonnaldehyde (...

Effect of resin type on properties of steam-press-cured flakeboards

Treesearch

Chung-Yun Hse; Robert L. Geimer; W. Earnest Hsu; R.C. Tang

1995-01-01

Six potentially important wood adhesives for gluing southern pine and white oak flakeboards were evaluated for their performances in steam-injection pressing and conventional platen pressing. Of the six resins tested, polyisocyanate resin performed well in both steam injection and conventional platen pressings. Phenol-formaldehyde (PF) and melamine urea-formaldehyde (...

Melaminium nitrate–melamine–water (1/1/1)

PubMed Central

Adam, Farook; Lin, Sek Kei; Hello, Kasim Mohammed; Hemamalini, Madhukar; Fun, Hoong-Kun

2010-01-01

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. PMID:21589188

Nitrogen enriched mesoporous organic polymer anchored copper(II) material: an efficient and reusable catalyst for the synthesis of esters and amides from aromatic systems.

PubMed

Molla, Rostam Ali; Iqubal, Md Asif; Ghosh, Kajari; Kamaluddin; Islam, Sk Manirul

2015-04-14

A new copper-grafted mesoporous poly-melamine-formaldehyde (Cu-mPMF) has been synthesized from melamine and paraformaldehyde in DMSO medium, followed by grafting of Cu(ii) at its surface. Cu-mPMF has been characterized by elemental analysis, powder XRD, HR TEM, FE-SEM, N2 adsorption study, FT-IR, UV-vis DRS, TGA-DTA, EPR spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The Cu-grafted mesoporous material showed very good catalytic activity in methyl esterification of benzylic alcohols and amidation of nitriles. Moreover, the catalyst is easily recoverable and can be reused seven times without appreciable loss of catalytic activity in the above reactions. The highly dispersed and strongly bound Cu(ii) sites in the Cu-grafted mesoporous polymer could be responsible for the observed high activities of the Cu-mPMF catalyst. Due to strong binding with the functional groups of the polymer, no evidence of leached copper from the catalyst during the course of reaction emerged, suggesting true heterogeneity in the catalytic process.

Development of a technique using MCNPX code for determination of nitrogen content of explosive materials using prompt gamma neutron activation analysis method

NASA Astrophysics Data System (ADS)

Nasrabadi, M. N.; Bakhshi, F.; Jalali, M.; Mohammadi, A.

2011-12-01

Nuclear-based explosive detection methods can detect explosives by identifying their elemental components, especially nitrogen. Thermal neutron capture reactions have been used for detecting prompt gamma 10.8 MeV following radioactive neutron capture by 14N nuclei. We aimed to study the feasibility of using field-portable prompt gamma neutron activation analysis (PGNAA) along with improved nuclear equipment to detect and identify explosives, illicit substances or landmines. A 252Cf radio-isotopic source was embedded in a cylinder made of high-density polyethylene (HDPE) and the cylinder was then placed in another cylindrical container filled with water. Measurements were performed on high nitrogen content compounds such as melamine (C3H6N6). Melamine powder in a HDPE bottle was placed underneath the vessel containing water and the neutron source. Gamma rays were detected using two NaI(Tl) crystals. The results were simulated with MCNP4c code calculations. The theoretical calculations and experimental measurements were in good agreement indicating that this method can be used for detection of explosives and illicit drugs.

Effects of melamine formaldehyde resin and CaCO3 diffuser-loaded encapsulation on correlated color temperature uniformity of phosphor-converted LEDs.

PubMed

Yang, Liang; Lv, Zhicheng; Jiaojiao, Yuan; Liu, Sheng

2013-08-01

Phosphor-free dispensing is the most widely used LED packaging method, but this method results in poor quality in angular CCT uniformity. This study proposes a diffuser-loaded encapsulation to solve the problem; the effects of melamine formaldehyde (MF) resin and CaCO3 loaded encapsulation on correlated color temperature (CCT) uniformity and luminous efficiency reduction of the phosphor-converted LEDs are investigated. Results reveal that MF resin loaded encapsulation has better light diffusion performance compared to MF resin loaded encapsulation at the same diffuser concentration, but CaCO3 loaded encapsulation has better luminous efficiency maintenance. The improvements in angular color uniformity for the LEDs emitting with MF resin and CaCO3 loaded encapsulation can be explained by the increase in photon scattering. The utility of this low cost and controllable mineral diffuser packaging method provides a practical approach for enhancing the angular color uniformity of LEDs. The diffuser mass ratio of 1% MF resin or 10% CaCO3 is the optimum condition to obtain low angular CCT variance and high luminous efficiency.

One-Step Synthesis of Fluorescent Boron Nitride Quantum Dots via a Hydrothermal Strategy Using Melamine as Nitrogen Source for the Detection of Ferric Ions.

PubMed

Huo, Bingbing; Liu, Bingping; Chen, Tao; Cui, Liang; Xu, Gengfang; Liu, Mengli; Liu, Jingquan

2017-10-10

A facile and effective approach for the preparation of functionalized born nitride quantum dots (BNQDs) with blue fluorescence was explored by the hydrothermal treatment of the mixture of boric acid and melamine at 200 °C for 15 h. The as-prepared BNQDs were characterized by transmission electron microscopy (TEM), high-resolution TEM, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The single layered BNQDs with the average size of 3 nm showed a blue light emission under the illumination of the UV light. The BNQDs could be easily dispersed in an aqueous medium and applied as fluorescent probes for selective detection of Fe 3+ with remarkable selectivity and sensitivity (the lowest detection limit was 0.3 μM). The fluorescence fiber imaging demonstrated that the as-prepared quantum dots could be used as a valuable fluorchrome. Therefore, the BNQDs could be envisioned for potential applications in many fields such as biocompatible staining, fluorescent probes, and biological labeling.

Gold Nanoparticle-Based Facile Detection of Human Serum Albumin and Its Application as an INHIBIT Logic Gate.

PubMed

Huang, Zhenzhen; Wang, Haonan; Yang, Wensheng

2015-05-06

In this work, a facile colorimetric method is developed for quantitative detection of human serum albumin (HSA) based on the antiaggregation effect of gold nanoparticles (Au NPs) in the presence of HSA. The citrate-capped Au NPs undergo a color change from red to blue when melamine is added as a cross-linker to induce the aggregation of the NPs. Such an aggregation is efficiently suppressed upon the adsorption of HSA on the particle surface. This method provides the advantages of simplicity and cost-efficiency for quantitative detection of HSA with a detection limit of ∼1.4 nM by monitoring the colorimetric changes of the Au NPs with UV-vis spectroscopy. In addition, this approach shows good selectivity for HSA over various amino acids, peptides, and proteins and is qualified for detection of HSA in a biological sample. Such an antiaggregation effect can be further extended to fabricate an INHIBIT logic gate by using HSA and melamine as inputs and the color changes of Au NPs as outputs, which may have application potentials in point-of-care medical diagnosis.

Adverse child health impacts resulting from food adulterations in the Greater China Region.

PubMed

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.

Migration of formaldehyde from melamine-ware: UK 2008 survey results.

PubMed

Potter, E L J; Bradley, E L; Davies, C R; Barnes, K A; Castle, L

2010-06-01

Fifty melamine-ware articles were tested for the migration of formaldehyde - with hexamethylenetetramine (HMTA) expressed as formaldehyde - to see whether the total specific migration limit (SML(T)) was being observed. The SML(T), given in European Commission Directive 2002/72/EC as amended, is 15 mg kg(-1). Fourier transform-infrared (FT-IR) spectroscopy was carried out on the articles to confirm the plastic type. Articles were exposed to the food simulant 3% (w/v) aqueous acetic acid under conditions representing their worst foreseeable use. Formaldehyde and HMTA in food simulants were determined by a spectrophotometric derivatization procedure. Positive samples were confirmed by a second spectrophotometric procedure using an alternative derivatization agent. As all products purchased were intended for repeat use, three sequential exposures to the simulant were carried out. Formaldehyde was detected in the simulant exposed to 43 samples. Most of the levels found were well below the limits set in law such that 84% of the samples tested were compliant. However, eight samples had formaldehyde levels that were clearly above the legal maximum at six to 65 times the SML(T).

Crystal structure, vibrational and DFT simulation studies of melaminium dihydrogen phosphite monohydrate

NASA Astrophysics Data System (ADS)

Arjunan, V.; Kalaivani, M.; Marchewka, M. K.; Mohan, S.

2013-08-01

The crystal structure investigations of melamine with phosphorous acid, namely melaminium dihydrogenphosphite monohydrate (C3N6H7·H2PO3·H2O) have been investigated by means of single crystal X-ray diffraction method. The title compound crystallizes in monoclinic crystal system, and the space group is P21/c with a = 10.069 Å, b = 21.592 Å, c = 12.409 Å and Z = 12. The vibrational assignments and analysis of melaminium dihydrogen phosphite monohydrate have also been performed by FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical simulations were performed with DFT (B3LYP) method using 6-31G**, cc-pVTZ, and 6-311++G** basis sets to determine the energy, structural, thermodynamic parameters and vibrational frequencies of melaminium dihydrogen phosphite monohydrate. The hydrogen atom from phosphorous acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak Osbnd H···O and Nsbnd H···O hydrogen bonds shows notable vibrational effects.

Study of stone composition changes in melamine-related urinary calculi and its clinical significance.

PubMed

Li, Yuan; Chen, YiRong; Zhang, Wei; Huang, XiaoGang; Li, WenHui; Ru, XiaoRui; Meng, Min; Xi, Xinsheng; Huang, Gang; Shi, BaoGuang; Liu, Gang; Li, WeiHua; Xu, Hui

2011-08-01

To investigate the composition changes in melamine-related urinary calculi and their clinical significance. A total of 49 melamine-related urinary calculi were included from 49 children (age 4-82 months, mean 22). The qualitative analysis of stone composition was determined using Fourier transform infrared. The quantitative analysis of the stone computed tomography (CT) attenuation value, stone uric acid level, and stone calcium level were measured using spiral CT, high-performance liquid chromatography, and flame atomic absorption spectrum, respectively. Fourier transform infrared showed that 41 (84%) of the 49 stones contained uric acid and 25 (51%) contained calcium compounds. The data from the qualitative and quantitative analysis were available for 15 stones because of sample consumption in the detection process (Fourier transform infrared, atomic absorption spectrum, and high-performance liquid chromatography). A negative correlation was observed between stone uric acid level and stone calcium level (n = 15, r = -0.629, P = .009). A positive correlation was observed between the stone calcium level and stone CT attenuation value (n = 25, r = 0.855, P = .000). Compared with the ≤1-year-age group and the 1-2-year-age group, the stone calcium level in the >2-year-age group was significantly greater (27.51% ± 12.65% vs 1.60% ± 1.68% or 10.12% ± 8.69%, P = .000 and P = .003, respectively). Compared with the alkalization-alone group, the stone calcium level in the nonalkalization-alone group was significant greater (19.83% ± 7.48% vs 1.25% ± 1.43%, n = 19, P = .000). The stones from children >2 years old were not amenable to medical treatment because they contained greater levels of calcium, which can be demonstrated by the radiologic "positive stone image" or stone CT attenuation value. We believe that surgical invention will be the best choice for such patients if extracorporeal shock wave lithotripsy has failed. Copyright © 2011 Elsevier Inc. All rights reserved.

Does size matter? Study of performance of pseudo-ELISAs based on molecularly imprinted polymer nanoparticles prepared for analytes of different sizes.

PubMed

Cáceres, C; Canfarotta, F; Chianella, I; Pereira, E; Moczko, E; Esen, C; Guerreiro, A; Piletska, E; Whitcombe, M J; Piletsky, S A

2016-02-21

The aim of this work is to evaluate whether the size of the analyte used as template for the synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) can affect their performance in pseudo-enzyme linked immunosorbent assays (pseudo-ELISAs). Successful demonstration of a nanoMIPs-based pseudo-ELISA for vancomycin (1449.3 g mol(-1)) was demonstrated earlier. In the present investigation, the following analytes were selected: horseradish peroxidase (HRP, 44 kDa), cytochrome C (Cyt C, 12 kDa) biotin (244.31 g mol(-1)) and melamine (126.12 g mol(-1)). NanoMIPs with a similar composition for all analytes were synthesised by persulfate-initiated polymerisation in water. In addition, core-shell nanoMIPs coated with polyethylene glycol (PEG) and imprinted for melamine were produced in organics and tested. The polymerisation of the nanoparticles was done using a solid-phase approach with the correspondent template immobilised on glass beads. The performance of the nanoMIPs used as replacement for antibodies in direct pseudo-ELISA (for the enzymes) and competitive pseudo-ELISA for the smaller analytes was investigated. For the competitive mode we rely on competition for the binding to the nanoparticles between free analyte and corresponding analyte-HRP conjugate. The results revealed that the best performances were obtained for nanoMIPs synthesised in aqueous media for the larger analytes. In addition, this approach was successful for biotin but completely failed for the smallest template melamine. This problem was solved using nanoMIP prepared by UV polymerisation in an organic media with a PEG shell. This study demonstrates that the preparation of nanoMIP by solid-phase approach can produce material with high affinity and potential to replace antibodies in ELISA tests for both large and small analytes. This makes this technology versatile and applicable to practically any target analyte and diagnostic field.

Development of Nonelectronic Part Cyclic Failure Rates

DTIC Science & Technology

1977-12-01

Schilling, W. A., "The User-Oriented Connector," Microwave Journal, Octcber 1976 40. Schneider, C., "Military Relay Reliability," Bell Telephone...polyimide B Diallyl phthalate, melamine , -55 to 200 fluorosilicone, silicone rubber, polysulfone, epoxy resin C Polytetrafluoroethylene (teflon) -55 to 125...propagation, solid state sciences, microwave physics and electronic reliability, maintainabilitg andcompatibility. .,% -UT104, , 8. g z

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

Treesearch

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...

Asphaltenes-based polymer nano-composites

DOEpatents

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.

Physical and mechanical properties and fire, decay, and termite resistance of treated oriented strandboard

Treesearch

Nadir Ayrilmis; S Nami Kartal; Theodore L. Laufenberg; Jerrold E. Winandy; Robert H. White

2005-01-01

This study evaluated the effects of a number of chemicals on the physical and mechanical properties and fire, decay, and termite resistance of oriented strandboard (OSB) panels. Disodium octaborate tetrahydrate (DOT), boric acid (BA), melamine phosphate (MP), and a BA/DOT mixture were sprayed onto the furnish at varying concentrations. The panels were tested for...

Commandant’s International Technical Series. Volume 8. Fire Aboard the M.S. SCANDINAVIAN SEA on March 9, 1984. Technical Assessment

DTIC Science & Technology

1985-01-01

Bulkheads - 5/8" asbestos cement panels Ceilings - 3/8" asbestos cement panels Structural insulation - mineral wool Ducting and Hull Insulation-fibrous...glass/ mineral wool D6ryks - steel Linings - 3/4" and 5/8" asbestos cement panels Interior finish - melamine plastic laminate Furnishings - wood and

Remendable Polymeric Materials Using Reversible Covalent Bonds

DTIC Science & Technology

2008-12-01

Synthesis and characterization of melamine - urea - formaldehyde microcapsules containing ENB-based self-healing agents. International Conference on Smart...R. Wang, X. He, W. Liu, and H. Hao, 2007: Preparation and characterization of self-healing poly ( urea - formaldehyde ) microcapsules. International...captured much attention. In one method, polymer networks are made to self-heal by adding particles filled with uncured resin . The resin held

Vertically Aligned BCN Nanotubes as Efficient Metal-Free Electrocatalysts for the Oxygen Reduction Reaction: A Synergetic Effect by Co-Doping with Boron and Nitrogen

DTIC Science & Technology

2011-01-01

difficulties.[20–22] In most of the previous studies, ternary compounds (e.g., ferrocene , melamine, boron oxide) were used as precursors for nanotube...the onset/peak potential and current density, though the VA- NCNT (4.1% N) prepared by pyrolysis of ferrocene under ammonia (see Supporting

Microwave-assisted synthesis of highly fluorescent nanoparticles of a melamine-based porous covalent organic framework for trace-level detection of nitroaromatic explosives.

PubMed

Zhang, Wang; Qiu, Ling-Guang; Yuan, Yu-Peng; Xie, An-Jian; Shen, Yu-Hua; Zhu, Jun-Fa

2012-06-30

Covalent organic frameworks (COFs) are a new generation of porous materials constructed from light elements linked by strong covalent bonds. Herein we present rapid preparation of highly fluorescent nanoparticles of a new type of COF, i.e. melamine-based porous polymeric network SNW-1, by a microwave-assisted synthesis route. Although the synthesis of SNW-1 has to be carried out at 180°C for 3d under conventional reflux conditions, SNW-1 nanoparticles could be obtained in 6h by using such a microwave-assisted method. The results obtained have clearly demonstrated that microwave-assisted synthesis is a simple yet highly efficient approach to nanoscale COFs or other porous polymeric materials. Remarkably, the as-synthesized SNW-1 nanoparticles exhibit extremely high sensitivity and selectivity, as well as fast response to nitroaromatic explosives such as 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenylmethylnitramine (Tetryl) and picric acid (PA) without interference by common organic solvents, which is due to the nanoscaled size and unique hierarchical porosity of such fluorescence-based sensing material. Copyright © 2012 Elsevier B.V. All rights reserved.

Phosphorous and nitrogen dual heteroatom doped mesoporous carbon synthesized via microwave method for supercapacitor application

NASA Astrophysics Data System (ADS)

Nasini, Udaya B.; Bairi, Venu Gopal; Ramasahayam, Sunil Kumar; Bourdo, Shawn E.; Viswanathan, Tito; Shaikh, Ali U.

2014-03-01

Phosphorus (P) and nitrogen (N) dual heteroatom doped mesoporous carbon (PNDC) synthesized by microwave assisted carbonization of tannin cross-linked to melamine in the presence of polyphosphoric acid was evaluated electrochemically for supercapacitor application. Controlling the N content by varying the amount of tannin to melamine in the carbonization process produced varying nitrogen, phosphorus and oxygen functionalities along with different physical properties. Electrochemical characterization studies revealed that N content is responsible for pseudocapacitance and high surface area plays a vital role in improving the capacitative behavior by enhanced electric double layer formation. In 1.0 M H2SO4 and 6.0 M KOH, PNDC-2 showed a high specific capacitance of 271 F g-1 and 236 F g-1, respectively. XPS results demonstrate the presence of pyridinic-N, quaternary-N as well as quinone type oxygen functionalities, which accounts for redox reactions and likely play an important role in the transportation of electrons during the charge/discharge process. Thus, the microwave assisted synthesis of doped carbon can provide a novel method of synthesizing materials useful for the fabrication of cheap and high performance supercapacitors.

Effects of Electrospun Carbon Nanofibers' Interlayers on High-Performance Lithium-Sulfur Batteries.

PubMed

Gao, Tianji; Le, TrungHieu; Yang, Ying; Yu, Zhihao; Huang, Zhenghong; Kang, Feiyu

2017-03-31

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.

Effects of Electrospun Carbon Nanofibers’ Interlayers on High-Performance Lithium–Sulfur Batteries

PubMed Central

Gao, Tianji; Le, TrungHieu; Yang, Ying; Yu, Zhihao; Huang, Zhenghong; Kang, Feiyu

2017-01-01

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. PMID:28772731

Preparation and Properties of Melamine Urea-Formaldehyde Microcapsules for Self-Healing of Cementitious Materials

PubMed Central

Li, Wenting; Zhu, Xujing; Zhao, Nan; Jiang, Zhengwu

2016-01-01

Self-healing microcapsules were synthesized by in situ polymerization with a melamine urea-formaldehyde resin shell and an epoxy resin adhesive. The effects of the key factors, i.e., core–wall ratio, reaction temperature, pH and stirring rate, were investigated by characterizing microcapsule morphology, shell thickness, particle size distribution, mechanical properties and chemical nature. Microcapsule healing mechanisms in cement paste were evaluated based on recovery strength and healing microstructure. The results showed that the encapsulation ability, the elasticity modulus and hardness of the capsule increased with an increase of the proportion of shell material. Increased polymerization temperatures were beneficial to the higher degree of shell condensation polymerization, higher resin particles deposition on microcapsule surfaces and enhanced mechanical properties. For relatively low pH values, the less porous three-dimensional structure led to the increased elastic modulus of shell and the more stable chemical structure. Optimized microcapsules were produced at a temperature of 60 °C, a core-wall ratio of 1:1, at pH 2~3 and at a stirring rate of 300~400 r/min. The best strength restoration was observed in the cement paste pre-damaged by 30% fmax and incorporating 4 wt % of capsules. PMID:28773280

Synthesis and characterization of melamine-urea-formaldehyde microcapsules containing ENB-based self-healing agents

NASA Astrophysics Data System (ADS)

Liu, Xing; Sheng, Xia; Lee, Jong Keun; Kessler, Michael R.

2007-07-01

Microcapsules for self-healing applications were produced with a melamine-urea-formaldehyde (MUF) polymer shell containing two different healing agent candidates, ENB (5-ethylidene-2-norbornene) and ENB with 10 wt.% of a norbornene based crosslinking agent (CL), by in-situ polymerization in an oil-in-water emulsion. Relatively neat outer surfaces with minor roughness were observed on the MUF microcapsules under optical and scanning electron microscopy. Shell thickness of the capsules ranged from 700 to 900 nm. Particle size analysis of the microcapsules showed narrow size distributions with a mean diameter of 113 μm for ENB-filled and 122 μm for ENB+CL-filled microcapsules at an agitation rate of 500 rpm. The microcapsules were found to be thermally stable up to 300°C and exhibited a 10 to 15 % weight loss when isothermally held at 150°C for 2 hr from thermogravimetric analysis. Overall, these MUF microcapsules exhibited superior properties compared to the urea-formaldehyde (UF) microcapsules used extensively for self-healing composites to date. In addition, the manufacturing process of MUF microcapsules is much simpler than those made from UF. Additional advantages of MUF microcapsules for self-healing composites are discussed.

Influence of ligand chemistry on silver nanoparticles for colorimetric detection of Cr3+ and Hg2+ ions

NASA Astrophysics Data System (ADS)

Kailasa, Suresh Kumar; Chandel, Madhurya; Mehta, Vaibhavkumar N.; Park, Tae Jung

2018-04-01

In this work, we describe the role of ligand chemistry on the surfaces of silver nanoparticles (Ag NPs) for tuning their analytical applications. The citrate and melamine (MA) molecules were used as ligands for the surface modification of Ag NPs. The addition of Cr3+ ion in citrate-Ag NPs (Cit-Ag NPs) and of Hg2+ ion in melamine-Ag NPs (MA-Ag NPs) cause Ag NPs aggregation, and are accompanied by a color change and a red-shift. The resulting distinctly visual readouts are favorable for colorimetric detection of Cr3+ and Hg2+ ions. Under optimal conditions, the linear ranges are observed in the concentration ranges of 1.0-50.0 and of 10.0-100.0 μM, and with detection limit of 0.52 and 1.80 μM for Cr3+ and Hg2+ ions. The simultaneous detection of Cr3+ and Hg2+ ion is driven by the changing the ligand chemistry on the surfaces of Ag NPs that allows to tune their specific interactions with target analytes. Finally, the functionalized Ag NPs were successfully applied to detect Cr3+ and Hg2+ ions in water samples with satisfactory recoveries.

Sensitive determination of melamine in milk and powdered infant formula samples by high-performance liquid chromatography using dabsyl chloride derivatization followed by dispersive liquid-liquid microextraction.

PubMed

Faraji, M; Adeli, M

2017-04-15

A new and sensitive pre-column derivatization with dabsyl chloride followed by dispersive liquid-liquid microextraction was developed for the analysis of melamine (MEL) in raw milk and powdered infant formula samples by high performance liquid chromatography (HPLC) with visible detection. Derivatization with dabsyl chloride leads to improving sensitivity and hydrophobicity of MEL. Under optimum conditions of derivatization and microextraction steps, the method yielded a linear calibration curve ranging from 1.0 to 500μgL -1 with a determination coefficient (R 2 ) of 0.9995. Limit of detection and limit of quantification were 0.1 and 0.3μgL -1 , respectively. The relative standard deviation (RSD%) for intra-day (repeatability) and inter-day (reproducibility) at 25 and 100μgL -1 levels of MEL was less than 7.0% (n=6). Finally, the proposed method was successfully applied for the preconcentration and determination of MEL in different raw milk and powdered infant formula, and satisfactory results were obtained (relative recovery ⩾94%). Copyright © 2016 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Ying; Yang, Feng; Lee, Sungsik

Facile fabrication of manganese oxide (MnO x, 0 < x < 2) and nitrogen (N) co-doped carbon microspheres (MnO x-N-CS) has been firstly developed by one-pot construction of Mn-functionalized melamine-formaldehyde (Mn-MF) resin spheres before pyrolysis. The resulting hybrids bear evenly dispersed MnO x and N moieties in situ anchored on hierarchically porous carbon microspheres formed simultaneously. The capacitive performance is greatly tailored by varying the Mn/melamine molar ratio in the synthetic mixture and pyrolysis temperature. It is found that the MnO x-N-CS hybrid (0.008 wt% Mn, pyrolyzed at 800 °C) exhibits the highest specific capacitance up to 258 F gmore » –1 at a scan rate of 1 mV s –1 (in 6 M KOH), and keeps a high capacitance retention ratio of 98% after 5000 cycles. The synergism between MnO x, N moieties and carbon spheres proves to be responsible for the remarkably improved performance, as compared to the pure carbon sphere and MnO x (N)-doped carbon sphere. Lastly, the well-developed MnO x-N-CS hybrids highlight the great potentials for widespread supercapacitor applications.« less

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

NASA Astrophysics Data System (ADS)

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.

Facile preparation of three-dimensional Co1-xS/sulfur and nitrogen-codoped graphene/carbon foam for highly efficient oxygen reduction reaction

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

The development of an inert simulant for HNS/teflon explosive

NASA Technical Reports Server (NTRS)

Elban, W. L.

1972-01-01

The report describes the development and evaluation of an inert simulant for the thermally stable, heat-resistant plastic-bonded explosive HNS/Teflon. The simulant is made by dry blending vinylidene fluoride, melamine and Teflon which when compared has a pressed density and thermal properties corresponding closely to the explosive. In addition, the machinability and handling characteristics of the simulant are similar to the explosive.

JPRS Report, Soviet Union, Economic Affairs

DTIC Science & Technology

1988-06-28

reducing the application of melamine formaldehyde resins which are used for the final finishing processes of fabrics since a harmful sub- stance...superphosphate and urea for private plots. Many letters arrive from Siberia, the Urals, Moldavia and from the Moscow region. Even in Moscow itself...Progressive types of rolled metal, including galvanized steel sheet, as well as efficient plastics, resins , polymers, timber products etc., are being

Plastic Media Blasting Data Gathering Study

DTIC Science & Technology

1986-12-01

products of organic compounds containing the amino group (-NH 2 ) and an aldehyde. The better known members of this group are urea formaldehyde (a...suspected carcinogen) and melamine formaldehyde . The actual composition and toxicity of the dust from the various operations must be collected and...blasting is a paint removal technique in which small, granular amino thermoset or unsaturated polyester resins (plastic beads) are forced at high

Effects of calcining temperature on photocatalysis of g-C{sub 3}N{sub 4}/TiO{sub 2} composites for hydrogen evolution from water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, Ailan, E-mail: elainqal@163.com; Xu, Xinmei; Xie, Haolong

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 wasmore » 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}.« less

The Fracture of Thermosetting Resins after Exposure to Water.

DTIC Science & Technology

1980-09-01

formaldehyde , urea - formaldehyde and melamine - formaldehyde resins , epoxides, unsaturated polyesters, diallyl phthalate resins , furanes and certain kinds...linked phenol- formaldehyde (27) and epoxy resins (22), but some work on the fracture surfaces of polyesters with varying flexibiliser additions has been...AO0-A099 975 KINGSTON POLYTECHNIC KINGSTON UPON THAMES (ENGLAND) F/G 11/9 THE FRACTURE OF THERMOSETTING RESINS AFTER EXPOSURE TO WATER.(U) SEP 80 6

Raman spectroscopy and imaging to detect contaminants for food safety applications

NASA Astrophysics Data System (ADS)

Chao, Kuanglin; Qin, Jianwei; Kim, Moon S.; Peng, Yankun; Chan, Diane; Cheng, Yu-Che

2013-05-01

This study presents the use of Raman chemical imaging for the screening of dry milk powder for the presence of chemical contaminants and Raman spectroscopy for quantitative assessment of chemical contaminants in liquid milk. For image-based screening, melamine was mixed into dry milk at concentrations (w/w) between 0.2% and 10.0%, and images of the mixtures were analyzed by a spectral information divergence algorithm. Ammonium sulfate, dicyandiamide, and urea were each separately mixed into dry milk at concentrations (w/w) between 0.5% and 5.0%, and an algorithm based on self-modeling mixture analysis was applied to these sample images. The contaminants were successfully detected and the spatial distribution of the contaminants within the sample mixtures was visualized using these algorithms. Liquid milk mixtures were prepared with melamine at concentrations between 0.04% and 0.30%, with ammonium sulfate and with urea at concentrations between 0.1% and 10.0%, and with dicyandiamide at concentrations between 0.1% and 4.0%. Analysis of the Raman spectra from the liquid mixtures showed linear relationships between the Raman intensities and the chemical concentrations. Although further studies are necessary, Raman chemical imaging and spectroscopy show promise for use in detecting and evaluating contaminants in food ingredients.

Isoelectric point and adsorption activity of porous g-C3N4

NASA Astrophysics Data System (ADS)

Zhu, Bicheng; Xia, Pengfei; Ho, Wingkei; Yu, Jiaguo

2015-07-01

The isoelectric point (IEP) is an important physicochemical parameter of many compounds, such as oxides, hydroxides, and nitrides, and can contribute to estimation of the surface charges of compound particles at various pH conditions. In this work, three types of graphitic carbon nitrides (g-C3N4) were synthesized by directly heating melamine, thiourea, and urea. The prepared samples showed different microstructures and IEPs that influenced their adsorption activity. Differences in microstructure resulted from the various precursors used during synthesis. The IEPs of the obtained g-C3N4 were measured to be approximately 4-5, which is due to the equilibrium of chemical reactions between hydrogen ions, hydroxyl ions, and amine groups on the g-C3N4 surface. The IEP of g-C3N4 prepared from thiourea was lower than those of the corresponding samples prepared from melamine and urea. The adsorption activity of methylene blue on g-C3N4 prepared from urea and thiourea was excellent, which indicates that g-C3N4 is a promising adsorbent. This work provides a useful reference for choosing precursors with which to prepare g-C3N4 and combining g-C3N4 with other compounds in solution.

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

PubMed Central

Kim, Tae-Hee; Choi, Sooseok; Park, Dong-Wha

2016-01-01

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(NO3)3∙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. PMID:28344295

Facile fabrication of MnO x and N co-doped hierarchically porous carbon microspheres for high-performance supercapacitors

DOE PAGES

Yang, Ying; Yang, Feng; Lee, Sungsik; ...

2016-01-16

Facile fabrication of manganese oxide (MnO x, 0 < x < 2) and nitrogen (N) co-doped carbon microspheres (MnO x-N-CS) has been firstly developed by one-pot construction of Mn-functionalized melamine-formaldehyde (Mn-MF) resin spheres before pyrolysis. The resulting hybrids bear evenly dispersed MnO x and N moieties in situ anchored on hierarchically porous carbon microspheres formed simultaneously. The capacitive performance is greatly tailored by varying the Mn/melamine molar ratio in the synthetic mixture and pyrolysis temperature. It is found that the MnO x-N-CS hybrid (0.008 wt% Mn, pyrolyzed at 800 °C) exhibits the highest specific capacitance up to 258 F gmore » –1 at a scan rate of 1 mV s –1 (in 6 M KOH), and keeps a high capacitance retention ratio of 98% after 5000 cycles. The synergism between MnO x, N moieties and carbon spheres proves to be responsible for the remarkably improved performance, as compared to the pure carbon sphere and MnO x (N)-doped carbon sphere. Lastly, the well-developed MnO x-N-CS hybrids highlight the great potentials for widespread supercapacitor applications.« less

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

NASA Astrophysics Data System (ADS)

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.

Relative humidity effects on the surface electrical properties of resistive plate chamber melaminic laminates uncoated and coated with polymerized linseed oil film

NASA Astrophysics Data System (ADS)

Bearzotti, Andrea; Palummo, Lucrezia

2007-09-01

Relative humidity is an important quantity to control in many manufacturing environments such as semiconductor industry. Humidity and moisture can affect many electronic devices, generally rendering their operation worse. In this study we present results showing that in some specific applications, humidity can improve the performance of an electronic device. Resistive plate chambers are used as trigger detectors of the muon system in LHC (large hadron collider) experiments ATLAS (a toroidal LHC apparatus), CMS (compact muon solenoid) and ALICE (a large ion collider experiment) and as detector in cosmic rays experiment ARGO (astrophysical radiation with ground-based observatory). These detectors are made of phenolic-melaminic laminate electrodes, coated with a polymerized linseed oil film delimiting the gaseous sensitive volume. The loss of some of the detector capability can be progressive in time and due to the intrinsic limits of the detector materials. One of these effects is due to an increase of the total plate resistance, that is correlated to ion migration and relativity humidity phenomena. Our purpose is to understand the relative humidity (RH) influence on the conduction mechanisms on the electrodes surface. Results of amperometric measurements on laminate samples kept at a fixed temperature of 22°C, cycling RH between 10% and 90% are here presented.

Determination and confirmation of melamine residues in catfish, trout, tilapia, salmon, and shrimp by liquid chromatography with tandem mass spectrometry.

PubMed

Andersen, Wendy C; Turnipseed, Sherri B; Karbiwnyk, Christine M; Clark, Susan B; Madson, Mark R; Gieseker, Charles M; Miller, Ron A; Rummel, Nathan G; Reimschuessel, Renate

2008-06-25

Pet and food animal (hogs, chicken, and fish) feeds were recently found to be contaminated with melamine (MEL). A quantitative and confirmatory method is presented to determine MEL residues in edible tissues from fish fed this contaminant. Edible tissues were extracted with acidic acetonitrile, defatted with dichloromethane, and cleaned up using mixed-mode cation exchange solid-phase extraction cartridges. Extracts were analyzed by liquid chromatography with tandem mass spectrometry with hydrophilic interaction chromatography and electrospray ionization in positive ion mode. Fish and shrimp tissues were fortified with 10-500 microg/kg (ppb) of MEL with an average recovery of 63.8% (21.5% relative standard deviation, n = 121). Incurred fish tissues were generated by feeding fish up to 400 mg/kg of MEL or a combination of MEL and the related triazine cyanuric acid (CYA). MEL and CYA are known to form an insoluble complex in the kidneys, which may lead to renal failure. Fifty-five treated catfish, trout, tilapia, and salmon were analyzed after withdrawal times of 1-14 days. MEL residues were found in edible tissues from all of the fish with concentrations ranging from 0.011 to 210 mg/kg (ppm). Incurred shrimp and a survey of market seafood products were also analyzed as part of this study.

Design Guide: Designing and Building High Voltage Power Supplies. Volume 2

DTIC Science & Technology

1988-08-01

and edges. * Isolation system: * One layer ol’ Tedlar: or type 120 glass fabric with a compatible resin : or finish. 199 5.4.2 Composite Joints...plastics Cellulose esters Asphalt Cork Chloride flux Epoxy resins Copper (bare) Masonite Fiber board Melamine resins Greases Nylon Polyvinyl chloride resins ...cycloaliphatic epoxy to a level inferior to the porcelain. In one application having a glass -cloth epoxy- based laminate coated with cycloaliphatic epoxy the

Demonstration Testing of Plastic Media Blasting (PMB) at LetterKenny Army Depot.

DTIC Science & Technology

1989-01-10

media can typically be purchased in three grades; Type I (polyester), Type II ( urea formaldehyde ), and Type III ( melamine formaldehyde ). The hardness of...outlet for waste thermoset resin from button making operations. As plastic media is synthetic, the~properties of plastic oedia can be controlled to a...After the oven comes to temperature, the parts are heated for an appropriate time, usually several hours, to pyrolyze the organic resin coating. The

A Study of Agent-Reactive Fabrics for Use in Protective Clothing.

DTIC Science & Technology

1979-12-01

insoluble state with amino ( urea or melamine - formaldehyde ), phenolic, epoxy, hydroxyl-containing or isocyanate resins , or with inorganic salts. Poly...late 1920’s and early 1930’s of a clothing- impregnating process based on the inpregnant sym-bis-(chloro-2,4,6-trichlorophenyl) urea (CC-2), which...followed by introduction of a plasticizer and final fabric treatment by either impregnation or "wet"-coating processes. More recent advances in resin

INVESTIGATION TO CHARACTERIZE THE WEATHERING PROPERTIES OF CELLULOSE PAPER TREATED WITH CERTAIN SYNTHETIC RESINS.

DTIC Science & Technology

melamine formaldehyde monomer was conducted on a pilot-plant scale. Several recommendations are made for carrying forward the promising results shown by this study and eventually achieving commercial utilization. (Author)...The investigation of the effectiveness of resin treatments in protecting paper from rot and weathering has included the following specific objectives...Determination of the relative effectiveness of a spectrum of different resins ; Selection of effective and practical conditions for resin

Explosibility and Ignitability of Plastic Abrasive Media.

DTIC Science & Technology

1987-06-01

Polyplus Is an alpha cellulose filled urea formaldehyde with a hardness or 3.5. Type III is a urea melamine formaldehyde with a hardness of 4. A fourth...is a thermoplastic acrylic media and the Kopper’s media are thermoset formaldehydes . o The greatest potential for dust explosions is in the baghouss...type or plastio media trom E. I. Du Pont de Nemours and Company was also tested. This Type L Solidstrip plastic stripping abrasive is an acrylic resin

Poly-4-vinylphenol (PVP) and Poly(melamine-co-formaldehyde) (PMF)-Based Atomic Switching Device and Its Application to Logic Gate Circuits with Low Operating Voltage.

PubMed

Kang, Dong-Ho; Choi, Woo-Young; Woo, Hyunsuk; Jang, Sungkyu; Park, Hyung-Youl; Shim, Jaewoo; Choi, Jae-Woong; Kim, Sungho; Jeon, Sanghun; Lee, Sungjoo; Park, Jin-Hong

2017-08-16

In this study, we demonstrate a high-performance solid polymer electrolyte (SPE) atomic switching device with low SET/RESET voltages (0.25 and -0.5 V, respectively), high on/off-current ratio (10 5 ), excellent cyclic endurance (>10 3 ), and long retention time (>10 4 s), where poly-4-vinylphenol (PVP)/poly(melamine-co-formaldehyde) (PMF) is used as an SPE layer. To accomplish these excellent device performance parameters, we reduce the off-current level of the PVP/PMF atomic switching device by improving the electrical insulating property of the PVP/PMF electrolyte through adjustment of the number of cross-linked chains. We then apply a titanium buffer layer to the PVP/PMF switching device for further improvement of bipolar switching behavior and device stability. In addition, we first implement SPE atomic switch-based logic AND and OR circuits with low operating voltages below 2 V by integrating 5 × 5 arrays of PVP/PMF switching devices on the flexible substrate. In particular, this low operating voltage of our logic circuits was much lower than that (>5 V) of the circuits configured by polymer resistive random access memory. This research successfully presents the feasibility of PVP/PMF atomic switches for flexible integrated circuits for next-generation electronic applications.

Casting a global safety net--a framework for food safety in the age of globalization.

PubMed

Chyau, James

2009-01-01

In mid-March 2007, Ontario-based Menu Foods Inc. started recalling its "cuts and gravy" style pet food, after receiving information that pets that had eaten the product had fallen ill. Within a week, the company was inundated with complaints and expressions of concern from about 200,000 of its customers. The Food and Drug Administration (FDA) determined in late March 2007 that the most likely culprit in the illness, and in some cases death of the pet animals, was contaminated wheat gluten, a vegetable protein imported from China. One of the FDA identified contaminants was an industrial chemical called melamine. Reports of widespread adulteration of animal feed with melamine in China raised concern of similar contamination in the human food supply. In response, on April 27, 2007, FDA announced the detention of all vegetable proteins imported from China, whether for animal or for human consumption. But, FDA's action came too late. On May 1, 2007, officials from FDA and the U.S. Department of Agriculture (USDA) indicated that between 2.5 to 3 million people in the United States had consumed chickens that had been fed with contaminated vegetable proteins imported from China. The 2007 pet food recall incident provided an ominous early warning that, unless the international community can come up with a better food safety mechanism, more such food contamination disasters could happen in the future.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuenca, Jacques, E-mail: jcuenca@kth.se; Van der Kelen, Christophe; Göransson, Peter

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 modelmore » 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.« less

Ratiometric Nanothermometer Based on Rhodamine Dye-Incorporated F127-Melamine-Formaldehyde Polymer Nanoparticle: Preparation, Characterization, Wide-Range Temperature Sensing, and Precise Intracellular Thermometry.

PubMed

Wu, Youshen; Liu, Jiajun; Ma, Jingwen; Liu, Yongchun; Wang, Ya; Wu, Daocheng

2016-06-15

A series of fluorescent nanothermometers (FTs) was prepared with Rhodamine dye-incorporated Pluronic F-127-melamine-formaldehyde composite polymer nanoparticles (R-F127-MF NPs). The highly soluble Rhodamine dye molecules were bound with Pluronic F127 micelles and subsequently incorporated in the cross-linked MF resin NPs during high-temperature cross-link treatment. The morphology and chemical structure of R-F127-MF NPs were characterized with dynamic light scattering, electron microscopy, and Fourier-transform infrared (FTIR) spectra. Fluorescence properties and thermoresponsivities were analyzed using fluorescence spectra. R-F127-MF NPs are found to be monodispersed, presenting a size range of 88-105 nm, and have bright fluorescence and high stability in severe treatments such as autoclave sterilization and lyophilization. By simultaneously incorporating Rhodamine B and Rhodamine 110 (as reference) dyes at a doping ratio of 1:400 in the NPs, ratiometric FTs with a high sensibility of 7.6%·°C(-1) and a wide temperature sensing range from -20 to 110 °C were obtained. The FTs exhibit good stability in solutions with varied pH, ionic strengths, and viscosities and have similar working curves in both intracellular and extracellular environments. Cellular temperature variations in Hela cells during microwave exposure were successfully monitored using the FTs, indicating their considerable potential applications in the biomedical field.

A confined "microreactor" synthesis strategy to three dimensional nitrogen-doped graphene for high-performance sodium ion battery anodes

NASA Astrophysics Data System (ADS)

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.

Performance of urinary and gene expression biomarkers in detecting the nephrotoxic effects of melamine and cyanuric acid following diverse scenarios of co-exposure

PubMed Central

Bandele, Omari; Camacho, Luísa; Ferguson, Martine; Reimschuessel, Renate; Stine, Cynthia; Black, Thomas; Olejnik, Nicholas; Keltner, Zachary; Scott, Michael; Gamboa da Costa, Gonçalo; Sprando, Robert

2013-01-01

Although standard nephrotoxicity assessments primarily detect impaired renal function, KIM-1, clusterin, NGAL, osteopontin and TIMP-1 were recently identified biomarkers proposed to indicate earlier perturbations in renal integrity. The recent adulteration of infant and pet food with melamine (MEL) and structurally-related compounds revealed that co-ingestion of MEL and cyanuric acid (CYA) could form melamine–cyanurate crystals which obstruct renal tubules and induce acute renal failure. This study concurrently evaluated the ability of multiplexed urinary biomarker immunoassays and biomarker gene expression analysis to detect nephrotoxicity in F344 rats co-administered 60 ppm each of MEL and CYA in feed or via gavage for 28 days. The biomarkers were also evaluated for the ability to differentiate the effects of the compounds when co-administered using diverse dosing schedules (i.e., consecutive vs. staggered gavage) and dosing matrixes (i.e., feed vs. gavage). Our results illustrate the ability of both methods to detect and differentiate the severity of adverse effects in the staggered and consecutive gavage groups at much lower doses than previously observed in animals co-exposed to the compounds in feed. We also demonstrate that these urinary biomarkers outperform traditional diagnostic methods and represent a powerful, non-invasive indicator of chemical-induced nephrotoxicity prior to the onset of renal dysfunction. PMID:23022069

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Yinhai; Xiang, Xiaoxia; Liu, Enhui, E-mail: liuenhui99@sina.com.cn

Highlights: ► Microporous carbon was prepared by chemical activation of phenol-melamine-formaldehyde resin. ► Activation leads to high surface area, well-developed micropores. ► Micropores lead to strong intercalation between carbon and lithium ion. ► Large surface area promotes to improve the lithium storage capacity. -- Abstract: Microporous carbon anode materials were prepared from phenol-melamine-formaldehyde resin by ZnCl{sub 2} and KOH activation. The physicochemical properties of the obtained carbon materials were characterized by scanning electron microscope, X-ray diffraction, Brunauer–Emmett–Teller, and elemental analysis. The electrochemical properties of the microporous carbon as anode materials in lithium ion secondary batteries were evaluated. At a currentmore » density of 100 mA g{sup −1}, the carbon without activation shows a first discharge capacity of 515 mAh g{sup −1}. After activation, the capacity improved obviously. The first discharge capacity of the carbon prepared by ZnCl{sub 2} and KOH activation was 1010 and 2085 mAh g{sup −1}, respectively. The reversible capacity of the carbon prepared by KOH activation was still as high as 717 mAh g{sup −1} after 20 cycles, which was much better than that activated by ZnCl{sub 2}. These results demonstrated that it may be a promising candidate as an anode material for lithium ion secondary batteries.« less

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

NASA Astrophysics Data System (ADS)

Cuenca, Jacques; Van der Kelen, Christophe; Göransson, Peter

2014-02-01

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.

Synthesis of monodisperse molecularly imprinted microspheres with multi-recognition ability via precipitation polymerization for the selective extraction of cyromazine, melamine, triamterene and trimethoprim.

PubMed

Wang, Xian-Hua; Xie, Li-Fu; Dong, Qian; Liu, Hao-Long; Huang, Yan-Ping; Liu, Zhao-Sheng

2015-12-15

Through precipitation polymerization, three monodisperse molecularly imprinted polymers (MIPs) containing imprints of 2,4-diamino-6-methyl-1,3,5-triazine (DM), cyromazine (CY) or trimethoprim (TM), were synthesized using methacrylic acid as functional monomer, divinylbenzene as cross-linker, and a mixture of acetonitrile-toluene (90/10, v/v) as porogen. The morphology and selectivity of the MIPs were characterized and compared systematically. The MIPs had the best specific binding in pure acetonitrile, and the data of adsorption experiment were fitted well with Langmuir and Freundlich model. In addition, DM-MIPs showed the excellent binding and multi-recognition capability for CY, melamine (ME), triamterene (TA) and TM, and the binding capacity were 7.18, 7.56, 5.66 and 5.45μmol/g, respectively. Due to the pseudo template and the ability of multi-recognition, DM-MIPs as sorbent material could avoid the effect of template leakage on quantitative analysis. Therefore, DM-MIPs were used as a solid-phase extraction material to enrich ME, CY, TA and TM from different bio-matrix samples for high performance liquid chromatography analysis. Under the optimized conditions, the recoveries of three spiked levels in different bio-matrix samples were ranged from 80.9% to 91.5% with RSD≤4.2 (n=3). Copyright © 2015 Elsevier B.V. All rights reserved.

Formation of graphitic carbon nitride and boron carbon nitride film on sapphire substrate

NASA Astrophysics Data System (ADS)

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.

The 'partial resonance' of the ring in the NLO crystal melaminium formate: study using vibrational spectra, DFT, HOMO-LUMO and MESP mapping.

PubMed

Binoy, J; Marchewka, M K; Jayakumar, V S

2013-03-01

The molecular geometry and vibrational spectral investigations of melaminium formate, a potential material known for toxicity and NLO activity, has been performed. The FT IR and FT Raman spectral investigations of melaminium formate is performed aided by the computed spectra of melaminium formate, triazine, melamine, melaminium and formate ion, along with bond orders and PED, computed using the density functional method (B3LYP) with 6-31G(d) basis set and XRD data, to reveal intermolecular interactions of amino groups with neighbor formula units in the crystal, intramolecular H⋯H repulsion of amino group hydrogen with protonating hydrogen, consequent loss of resonance in the melaminium ring, restriction of resonance to N(3)C(1)N(1) moiety leading to special type resonance of the ring and the resonance structure of CO(2) group of formate ion. The 3D matrix of hyperpolarizability tensor components has been computed to quantify NLO activity of melamine, melaminium and melaminium formate and the hyperpolarizability enhancement is analyzed using computed plots of HOMO and LUMO orbitals. A new mechanism of proton transfer responsible for NLO activity has been suggested, based on anomalous IR spectral bands in the high wavenumber region. The computed MEP contour maps have been used to analyze the interaction of melaminium and formate ions in the crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Catalytic performance of heterogeneous Rh/C3N4 for the carbonylation of methanol

NASA Astrophysics Data System (ADS)

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.

Synergic Effect between Adsorption and Photocatalysis of Metal-Free g-C3N4 Derived from Different Precursors

PubMed Central

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

The `partial resonance' of the ring in the NLO crystal melaminium formate: Study using vibrational spectra, DFT, HOMO-LUMO and MESP mapping

NASA Astrophysics Data System (ADS)

Binoy, J.; Marchewka, M. K.; Jayakumar, V. S.

2013-03-01

The molecular geometry and vibrational spectral investigations of melaminium formate, a potential material known for toxicity and NLO activity, has been performed. The FT IR and FT Raman spectral investigations of melaminium formate is performed aided by the computed spectra of melaminium formate, triazine, melamine, melaminium and formate ion, along with bond orders and PED, computed using the density functional method (B3LYP) with 6-31G(d) basis set and XRD data, to reveal intermolecular interactions of amino groups with neighbor formula units in the crystal, intramolecular H⋯H repulsion of amino group hydrogen with protonating hydrogen, consequent loss of resonance in the melaminium ring, restriction of resonance to N3C1N1 moiety leading to special type resonance of the ring and the resonance structure of CO2 group of formate ion. The 3D matrix of hyperpolarizability tensor components has been computed to quantify NLO activity of melamine, melaminium and melaminium formate and the hyperpolarizability enhancement is analyzed using computed plots of HOMO and LUMO orbitals. A new mechanism of proton transfer responsible for NLO activity has been suggested, based on anomalous IR spectral bands in the high wavenumber region. The computed MEP contour maps have been used to analyze the interaction of melaminium and formate ions in the crystal.

Risks associated with melamine and related triazine contamination of food

PubMed Central

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

Handbook of Pressure-Proof Connector and Cable Harness Design for Sonar Systems.

DTIC Science & Technology

1981-12-21

as delrin, polycarbonate, epoxy, melamine , and diallyl phthalate were evaluated. Glass -filled diallyl phthalate was the only candidate material which...and at 900 intervals on the bulk- head of glass sealed receptacles, 0.125 inch from the outermost glass bead . 7-3 :1 7.2.1.5 The area of the component...in their ability to cure resins , as well as their tendency to cause skin irritation or dermatitis. Most room temperature-set hardeners are based on

Intumescent Reaction Mechanisms: An Analytic Model.

DTIC Science & Technology

1983-05-01

or amide (such as urea , melamine , dicyan- diamide, urea formaldehyde , etc.) is the release of nonflammable gases (CO2, E . etc.) that physically...mo)/dT Versus I/T (Polysulfide) 34 5-3 Fourier Series Representation of TGA Data for Polysulfide, DIP-30, EPON Resin , and Borax 40 5-4 Fourier Series...Representation of TGA Data for Part A, Part B, and Part A+B 41 5-S Fourier Series Representation of d(m/m )/dT for Polysul- fide, DIP-30, EPOI Resin

Vibrational, calorimetric and nonlinear optical studies of melaminium-bis(trichloroacetate) monohydrate molecular ionic crystal

NASA Astrophysics Data System (ADS)

Debrus, S.; Marchewka, M. K.; Drozd, M.; Ratajczak, H.

2007-04-01

The efficiency of second harmonic generation for melaminium bis(trichloroacetate) was estimated relatively to KDP: deff = 3.09 deff (KDP). Room temperature FT IR and FT Raman spectra were recorded. Some spectral features of this new crystal are referred to corresponding one for melamine crystal as well as for other trichloroacetates. Differential scanning calorimetric measurements performed on powder sample indicate the phase transition point at approximately 276 and 239 K for heating and cooling, respectively.

Ultrathin g-C3N4 films supported on Attapulgite nanofibers with enhanced photocatalytic performance

NASA Astrophysics Data System (ADS)

Xu, Yongshuai; Zhang, Lili; Yin, Minghui; Xie, Dengyu; Chen, Jiaqi; Yin, Jingzhou; Fu, Yongsheng; Zhao, Pusu; Zhong, Hui; Zhao, Yijiang; Wang, Xin

2018-05-01

A novel visible-light-responsive photocatalyst is fabricated by introducing g-C3N4 ultrathin films onto the surface of attapulgite (ATP) via a simple in-situ depositing technique, in which ATP was pre-grafted using (3-Glycidyloxypropyl) trimethoxysilane (KH560) as the surfactant. A combination of XRD, FT-IR, BET, XPS, UV-vis, TEM and SEM techniques are utilized to characterize the composition, morphology and optical properties of the products. The results show that with the help of KH560, g-C3N4 presented as ultrathin layer is uniformly loaded onto the surface of ATP by forming a new chemical bond (Sisbnd Osbnd C). Comparing with g-C3N4 and ATP, ATP/g-C3N4 exhibits remarkably enhanced visible-light photocatalytic activity in degradation of methyl orange (MO) because of its high surface area, appropriate band gap and the synergistic effect between g-C3N4 and ATP. To achieve the best photocatalyst, the ratio of g-C3N4 was adjusted by controlling the mass portion between ATP-KH560 and melamine (r = m (ATP-KH560)/m (melamine)). The highest decomposition rate of methyl orange (MO) was 96.06% when r = 0.5 and this degradation efficiency remained unchanged after 4 cycles, which is 10 times as that of pure g-C3N4 particles. Possible photocatalytic mechanism is presented.

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

PubMed

Su, Ya-Ling; Cheng, Shu-Hua

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Compressible and Recyclable Monolithic g-C3N4/Melamine Sponge: A Facile Ultrasonic-Coating Approach and Enhanced Visible-Light Photocatalytic Activity.

PubMed

Yang, Ye; Zhang, Qian; Zhang, Ruiyang; Ran, Tao; Wan, Wenchao; Zhou, Ying

2018-01-01

Powdery photocatalysts seriously restrict their practical application due to the difficult recycle and low photocatalytic activity. In this work, a monolithic g-C 3 N 4 /melamine sponge (g-C 3 N 4 /MS) was successfully fabricated by a cost-effective ultrasonic-coating route, which is easy to achieve the uniform dispersion and firm loading of g-C 3 N 4 on MS skeleton. The monolithic g-C 3 N 4 /MS entirely inherits the porous structure of MS and results in a larger specific surface area (SSA) than its powdery counterpart. Benefit from this monolithic structure, g-C 3 N 4 /MS gains more exposed active sites, enhanced visible-light absorption and separation of photogenerated carriers, thus achieving noticeable photocatalytic activity on nitric oxide (NO) removal and CO 2 reduction. Specifically, NO removal ratio is as high as 78.6% which is 4.5 times higher than that of the powdery g-C 3 N 4 , and yield rate of CO and CH 4 attains 7.48 and 3.93 μmol g -1 h -1 . Importantly, the features of low-density, high porosity, good elasticity, and firmness, not only endow g-C 3 N 4 /MS with flexibility in various environmental applications, but also make it easy to recycle and stable for long-time application. Our work provides a feasible approach to fabricate novel monolithic photocatalysts with large-scale production and application.

Microporous carbons derived from melamine and isophthalaldehyde: One-pot condensation and activation in a molten salt medium for efficient gas adsorption.

PubMed

Rehman, Adeela; Park, Soo-Jin

2018-04-17

In the present work, mixture of melamine and isophthalaldehyde undergo simultaneous polymerization, carbonization, and in situ activation in the presence of molten salt media through a single all-in-one route to design microporous carbons with high specific surface areas (~3000 m 2 /g). The effect of the activation temperature and molten salts on the polymerization process and final texture of the carbon was explored. Carbon materials prepared at 700 °C, in the presence of KOH (referred as MIK-700), exhibited a narrower pore-size distribution ~1.05 nm than those prepared in the presence of the eutectic KOH-NaOH mixture (MIKN). Additionally, MIK-700 possesses an optimum micropore volume (1.33 cm 3 /g) along with a high nitrogen content (2.66 wt%), resulting in the excellent CO 2 adsorption capacity of 9.7 mmol/g at 273 K and 1 bar. Similarly, the high specific area and highest total pore volume play an important role in H 2 storage at 77 K, with 4.0 wt% uptake by MIKN-800 (specific surface area and pore volume of 2984 m 2 /g and 1.98 cm 3 /g, respectively.) Thus, the facile one-step solvent-free synthesis and activation strategy is an economically favorable avenue for designing microporous carbons as an efficient gas adsorbents.

Compressible and Recyclable Monolithic g-C3N4/Melamine Sponge: A Facile Ultrasonic-Coating Approach and Enhanced Visible-Light Photocatalytic Activity

PubMed Central

Yang, Ye; Zhang, Qian; Zhang, Ruiyang; Ran, Tao; Wan, Wenchao; Zhou, Ying

2018-01-01

Powdery photocatalysts seriously restrict their practical application due to the difficult recycle and low photocatalytic activity. In this work, a monolithic g-C3N4/melamine sponge (g-C3N4/MS) was successfully fabricated by a cost-effective ultrasonic-coating route, which is easy to achieve the uniform dispersion and firm loading of g-C3N4 on MS skeleton. The monolithic g-C3N4/MS entirely inherits the porous structure of MS and results in a larger specific surface area (SSA) than its powdery counterpart. Benefit from this monolithic structure, g-C3N4/MS gains more exposed active sites, enhanced visible-light absorption and separation of photogenerated carriers, thus achieving noticeable photocatalytic activity on nitric oxide (NO) removal and CO2 reduction. Specifically, NO removal ratio is as high as 78.6% which is 4.5 times higher than that of the powdery g-C3N4, and yield rate of CO and CH4 attains 7.48 and 3.93 μmol g−1 h−1. Importantly, the features of low-density, high porosity, good elasticity, and firmness, not only endow g-C3N4/MS with flexibility in various environmental applications, but also make it easy to recycle and stable for long-time application. Our work provides a feasible approach to fabricate novel monolithic photocatalysts with large-scale production and application.

Food and pharmaceuticals. Lessons learned from global contaminations with melamine/cyanuric acid and diethylene glycol.

PubMed

Brown, C A; Brown, S A

2010-01-01

Recently, contamination of pharmaceuticals with diethylene glycol (DEG) and food with melamine and cyanuric acid has demonstrated the impact of globalization on drug and food safety. By examining the details of these outbreaks, some important lessons can be learned. Toxicoses from contaminated food and drugs are often identified only when large numbers of people or animals are affected and numerous deaths result. Populations most at risk are those repeatedly exposed to a single product. Toxicoses may be complex, involving synergism among relatively nontoxic co-contaminants. Although some contamination may occur inadvertently, practices of deliberate contamination of food and drug ingredients may be widespread but escape detection in poorly regulated markets. If this deliberate contamination is motivated by personal financial gain, it is likely to recur and be concealed. The contaminated raw material produced in a poorly regulated market may cross national boundaries and be used in manufacturing processes for numerous products, sometimes in more well-regulated markets. Once in the production chain, contaminated raw materials may be widely disseminated. It is not clear that regulatory organizations have the capacity to identify significant contaminations despite their best efforts. The veterinary and medical communities, in cooperation with regulatory agencies, should develop cooperative programs designed to detect and limit these global outbreaks. Although addressing regional or national outbreaks remains an important role for regulatory agencies, the veterinary and medical communities must develop proactive global approaches to this global problem.

Comparison of multi-recognition molecularly imprinted polymers for recognition of melamine, cyromazine, triamterene, and trimethoprim.

PubMed

Wang, Xian-Hua; Zhang, Jing; Peng, Chao; Dong, Qian; Huang, Yan-Ping; Liu, Zhao-Sheng

2015-09-01

Three fragmental templates, including 2,4-diamino-6-methyl-1,3,5-triazine (DMT), cyromazine (CYR), and trimethoprim (TME), were used to prepare the fragment molecularly imprinted polymers (FMIPs), respectively, in polar ternary porogen which was composed of ionic liquid ([BMIM]BF4), methanol, and water. The morphology, specific surface areas, and selectivity of the obtained FMIPs for fragmental analogues were systematically characterized. The experimental results showed that the FMIPs possessed the best specific recognition ability to the relative template and the greatest imprinting factor (IF) was 5.25, 6.69, and 7.11 of DMT on DMT-MIPs, CYR on CYR-MIPs, and TME on TME-MIPs, respectively. In addition, DMT-MIPs also showed excellent recognition capability for fragmental analogues including CYR, melamine (MEL), triamterene (TAT), and TME, and the IFs were 2.08, 3.89, 2.18, and 2.60, respectively. The effects of pH and temperature on the retention of the fragmental and structural analogues were studied in detail. Van't Hoff analysis indicated that the retention and selectivity on FMIPs were an entropy-driven process, i.e., steric interaction. The resulting DMT-MIPs were used as a solid-phase extraction material to enrich CYR, MEL, TAT, and TME in different bio-matrix samples for high-performance liquid chromatography analysis. The developed method had acceptable recoveries (86.8-98.6%, n = 3) and precision (2.7-4.6%) at three spiked levels (0.05-0.5 μg g(-1)).

Single particle dynamics in a radio-frequency produced plasma sheath

NASA Astrophysics Data System (ADS)

Rubin-Zuzic, M.; Nosenko, V.; Zhdanov, S.; Ivlev, A.; Thomas, H.; Khrapak, S.; Couedel, L.

2018-01-01

Recently different research groups have investigated the motion of a single dust particle levitated in a rf plasma. Here we describe a highly resolved experiment where a single spherical melamine formaldehyde microparticle is suspended in the plasma sheath above the lower electrode of a capacitively coupled radio-frequency discharge at controlled pressure, power and neutral gas flow rate. The particle's horizontal oscillation is investigated, from which its neutral gas damping rate, kinetic temperature and eigenfrequency of the potential trap are measured. Compared to prior experiments we report about inhomogeneous and anisotropic velocity variations.

Synergistic increase of oxygen reduction favourable Fe-N coordination structures in a ternary hybrid of carbon nanospheres/carbon nanotubes/graphene sheets.

PubMed

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.

At-line validation of a process analytical technology approach for quality control of melamine-urea-formaldehyde resin in composite wood-panel production using near infrared spectroscopy.

PubMed

Meder, Roger; Stahl, Wolfgang; Warburton, Paul; Woolley, Sam; Earnshaw, Scott; Haselhofer, Klaus; van Langenberg, Ken; Ebdon, Nick; Mulder, Roger

2017-01-01

The reactivity of melamine-urea-formaldehyde resins is of key importance in the manufacture of engineered wood products such as medium density fibreboard (MDF) and other wood composite products. Often the MDF manufacturing plant has little available information on the resin reactivity other than details of the resin specification at the time of batch manufacture, which often occurs off-site at a third-party resin plant. Often too, fresh resin on delivery at the MDF plant is mixed with variable volume of aged resin in storage tanks, thereby rendering any specification of the fresh resin batch obsolete. It is therefore highly desirable to develop a real-time, at-line or on-line, process analytical technology to monitor the quality of the resin prior to MDF panel manufacture. Near infrared (NIR) spectroscopy has been calibrated against standard quality methods and against 13 C nuclear magnetic resonance (NMR) measures of molecular composition in order to provide at-line process analytical technology (PAT), to monitor the resin quality, particularly the formaldehyde content of the resin. At-line determination of formaldehyde content in the resin was made possible using a six-factor calibration with an R 2 (cal) value of 0.973, and R 2 (CV) value of 0.929 and a root-mean-square error of cross-validation of 0.01. This calibration was then used to generate control charts of formaldehyde content at regular four-hourly periods during MDF panel manufacture in a commercial MDF manufacturing plant.

Graphitic carbon nitride (g-C3N4) coated titanium oxide nanotube arrays with enhanced photo-electrochemical performance.

PubMed

Sun, Mingxuan; Fang, Yalin; Kong, Yuanyuan; Sun, Shanfu; Yu, Zhishui; Umar, Ahmad

2016-08-09

Herein, we report the successful formation of graphitic carbon nitride coated titanium oxide nanotube array thin films (g-C3N4/TiO2) via the facile thermal treatment of anodized Ti sheets over melamine. The proportion of C3N4 and TiO2 in the composite can be adjusted by changing the initial addition mass of melamine. The as-prepared samples are characterized by several techniques in order to understand the morphological, structural, compositional and optical properties. UV-vis absorption studies exhibit a remarkable red shift for the g-C3N4/TiO2 thin films as compared to the pristine TiO2 nanotubes. Importantly, the prepared composites exhibit an enhanced photocurrent and photo-potential under both UV-vis and visible light irradiation. Moreover, the observed maximum photo-conversion efficiency of the prepared composites is 1.59 times higher than that of the pristine TiO2 nanotubes. The optical and electrochemical impedance spectra analysis reveals that the better photo-electrochemical performance of the g-C3N4/TiO2 nanotubes is mainly due to the wider light absorption and reduced impedance compared to the bare TiO2 nanotube electrode. The presented work demonstrates a facile and simple method to fabricate g-C3N4/TiO2 nanotubes and clearly revealed that the introduction of g-C3N4 is a new and innovative approach to improve the photocurrent and photo-potential efficiencies of TiO2.

Melamine derivatives as effective corrosion inhibitors for mild steel in acidic solution: Chemical, electrochemical, surface and DFT studies

NASA Astrophysics Data System (ADS)

Verma, Chandrabhan; Haque, J.; Ebenso, Eno E.; Quraishi, M. A.

2018-06-01

In present study two condensation products of melamine (triazine) and glyoxal namely, 2,2-bis(4,6-diamino-1,3,5-triazin-2-ylamino)acetaldehyde (ME-1) and (N2,N2‧E,N2,N2‧E)-N2,N2‧-(ethane-1,2-diylidene)-bis-(1,3,5-triazine-2,4,6-triamine) (ME-2) are tested as mild steel corrosion inhibitors in acidic solution (1M HCl). The inhibition efficiency of ME-1 and ME-2 increases with increase in their concentrations and maximum values of 91.47% and 94.88% were derived, respectively at 100 mgL-1 (34.20 × 10-5 M) concentration. Adsorption of ME-1 and ME-2 on the surface of metal obeyed the Langmuir adsorption isotherm. Polarization investigation revealed that ME-1 and ME-2 act as mixed type inhibitors with minor cathodic prevalence. The chemical and electrochemical analyses also supported by surface characterization methods where significant smoothness in the surface morphologies was observed in the images of SEM and AFM spectra. Several DFT indices such as EHOMO and ELUMO, ΔE, η, σ, χ, μ and ΔN were derived for both ME-1 and ME-2 molecules and correlated with experimental results. The DFT studies have also been carried out for protonated or cationic form of the inhibitor molecules by considering that in acidic medium the heteroatoms of organic inhibitors easily undergo protonation. The experimental and density functional theory (DFT) studies (neutral and protonated) were in good agreement.

Adulteration detection in milk using infrared spectroscopy combined with two-dimensional correlation analysis

NASA Astrophysics Data System (ADS)

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.

Compressible and Recyclable Monolithic g-C3N4/Melamine Sponge: A Facile Ultrasonic-coating Approach and Enhanced Visible-light Photocatalytic Activity

NASA Astrophysics Data System (ADS)

Yang, Ye; Zhang, Qian; Zhang, Ruiyang; Ran, Tao; Wan, Wenchao; Zhou, Ying

2018-05-01

Powdery photocatalysts seriously restrict their practical application due to the difficult recycle and low photocatalytic activity. In this work, a monolithic g-C3N4/melamine sponge (g-C3N4/MS) was successfully fabricated by a cost-effective ultrasonic-coating route, which is easy to achieve the uniform dispersion and firm loading of g-C3N4 on MS skeleton. The monolithic g-C3N4/MS entirely inherits the porous structure of MS and results in a larger specific surface area (SSA) than its powdery counterpart. Benefit from this monolithic structure, g-C3N4/MS gains more exposed active sites, enhanced visible-light absorption and separation of photogenerated carriers, thus achieving noticeable photocatalytic activity on nitric oxide (NO) removal, rhodamine B (RhB) degradation and CO2 reduction. Specifically, NO removal ratio is as high as 78.6% which is 4.5 times higher than that of the powdery g-C3N4, while RhB degradation rate reaches 97.88%, and yield rate of CO and CH4 attains 7.48 and 3.93 μmol g-1 h-1. Importantly, the features of low-density, high porosity, good elasticity and firmness, not only endow g-C3N4/MS with flexibility in various environmental applications, but also make it easy to recycle and stable for long-time application. Our work provides a feasible approach to fabricate novel monolithic photocatalysts with large-scale production and application.

Electrochemiluminescence sensor for melamine based on a Ru(bpy)₃²⁺-doped silica nanoparticles/carboxylic acid functionalized multi-walled carbon nanotubes/Nafion composite film modified electrode.

PubMed

Chen, Xiaomei; Lian, Sai; Ma, Ying; Peng, Aihong; Tian, Xiaotian; Huang, Zhiyong; Chen, Xi

2016-01-01

In this work, a sensitive electrochemiluminescence (ECL) sensor for the determination of melamine (MEL) was developed based on a Ru(bpy)3(2+)-doped silica nanoparticles (RUDS)/carboxylic acid functionalized multi-walled carbon nanotubes (CMWCNTs)/Nafion composite film modified electrode. The homogeneous spherical RUDS were synthesized by a reverse microemulsion method. As Ru(bpy)3(2+) were encapsulated in the RUDS, Ru(bpy)3(2+) dropping from the modified electrode can be greatly prevented, which is helpful for obtaining a stable ECL signal. Moreover, to improve the conductivity of the film and promote the electron transfer rate on electrode surface, CMWCNTs with excellent electrical conductivity and large surface area were applied in the construction of the sensing film. As CMWCNTs acted as electron bridges making more Ru(bpy)3(2+) participate in the reaction, the ECL intensity was greatly enhanced. Under the optimum conditions, the relative ECL signal (△IECL) was proportional to the logarithmic MEL concentration ranging from 5×10(-13) to 1×10(-7) mol L(-1) with a detection limit of 1×10(-13) mol L(-1). To verify the reliability, the thus-fabricated ECL sensor was applied to determine the concentration of MEL in milk. Based on these investigations, the proposed ECL sensor exhibited good feasibility and high sensitivity for the determination of MEL, promising the applicability of this sensor in practical analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

CCQM-K103 key comparison melanine in milk powder

NASA Astrophysics Data System (ADS)

Li, Xiuqin; Zhang, Qinghe; Li, Hongmei; Li, Mengwan; Wong, Siu-kay; Lee, Foo-Wing; Kakoulides, Elias; Naujaus, Evaldas; Fernandes-Whaley, Maria; Prevoo-Franzsen, Des; Quinn, Laura; Pookrod, Preeyaporn; Konopelko, Leonid

2017-01-01

Under the Comité Consultatif pour la Quantité de Matière (CCQM), a key comparison, CCQM-K103, was coordinated by the National Institute of Metrology (NIM) and Government Laboratory, Hong Kong, China (GLHK). The comparison was designed to demonstrate NMIs/DIs ability to analyze traces of melamine in milk and milk powder at concentration levels resulting from requirements for food safety. Seven NMIs or DIs participated in the comparison. Final reference value (KCRV) is 0.286 mg/kg, with standard uncertainty of the median as 0.011 mg/kg (3.8 %). The k-factor for the estimation of the expanded uncertainty was chosen as k = 2.57 ( t (0.05;5) ), thus the expanded uncertainty is 0.028 mg/kg (9.8%). The degrees of equivalence with melamine in milk powder KCRV for each participant were reported. The measurement results and degrees of equivalence should be indicative of the performance of a laboratory's measurement capability for IDMS in determining mass fractions in the range from 0.1 to 5.0 mg/kg of analytes with low molar mass (range 50-300 Da) with high polarity (pKow > -2.0) in milk and milk products. Extension to other analytes and matrices should be applied with care since there is a close linkage to other relevant parameters as e.g. sample preparation procedures (liquid/liquid extraction, SPE clean-up) and analytical separation techniques (e.g., GC-MS, LC-MS/MS etc). Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Directed Self-Assembly in "Breath Figure" Templating of Melamine-Based Amphiphilic Copolymers: Effect of Hydrophilic End-Chain on Honeycomb Film Formation and Wetting.

PubMed

Yin, Hongyao; Feng, Yujun; Billon, Laurent

2018-01-09

Amphiphilic copolymers are widely used in the fabrication of hierarchically honeycomb-structured films through a "breath figure" (BF) process because the hydrophilic block plays a key role in stabilising water templating. However, the hydrophilic monomers reported are mainly confined to acrylic acid and its derivatives, which largely limits understanding of the formation of BF arrays and the introduction of additional functions on porous films. The relationship between polymer composition, film microstructure and surface properties are also less documented. Herein, a novel melamine-based hydrophilic moiety, N-[3-({3-[(4,6-bis{[3-(dimethylamino)propyl]amino}-1,3,5-triazin-2yl)amino]propyl}(methyl)amino)propyl]methacrylamide (ANME), was incorporated into polystyrene (PS) chains by combining atom-transfer radical polymerisation and post-modification to afford three well-defined end-functionalised PS-PANME derivatives. These polymers were used to fabricate honeycomb films through the BF technique. Both inner and outer microstructures of the films were characterised by optical microscopy, AFM and SEM. Polymer hydrophilicity is enhanced upon increasing the PANME content, which results in variation of the film microstructure and porosity, and provokes a transition from Cassie-Baxter to Wenzel behaviour. Furthermore, the surface wettability of as-prepared honeycomb films and corresponding pillared films is mainly governed by film morphology, rather than by the properties of the polymers. Knowledge of the relationships between polymer composition and film structure, as well as surface wettability, is beneficial to design and prepare hierarchically porous films with desirable structures and properties. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

In-syringe extraction using dissolvable layered double hydroxide-polymer sponges templated from hierarchically porous coordination polymers.

PubMed

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.

Nitrogen-doped porous graphitic carbon as an excellent electrode material for advanced supercapacitors.

PubMed

Sun, Li; Tian, Chungui; Fu, Yu; Yang, Ying; Yin, Jie; Wang, Lei; Fu, Honggang

2014-01-07

An advanced supercapacitor material based on nitrogen-doped porous graphitic carbon (NPGC) with high a surface area was synthesized by means of a simple coordination-pyrolysis combination process, in which tetraethyl orthosilicate (TEOS), nickel nitrate, and glucose were adopted as porogent, graphitic catalyst precursor, and carbon source, respectively. In addition, melamine was selected as a nitrogen source owing to its nitrogen-enriched structure and the strong interaction between the amine groups and the glucose unit. A low-temperature treatment resulted in the formation of a NPGC precursor by combination of the catalytic precursor, hydrolyzed TEOS, and the melamine-glucose unit. Following pyrolysis and removal of the catalyst and porogent, the NPGC material showed excellent electrical conductivity owing to its high crystallinity, a large Brunauer-Emmett-Teller surface area (SBET =1027 m(2)  g(-1) ), and a high nitrogen level (7.72 wt %). The unusual microstructure of NPGC materials could provide electrochemical energy storage. The NPGC material, without the need for any conductive additives, showed excellent capacitive behavior (293 F g(-1) at 1 A g(-1) ), long-term cycling stability, and high coulombic efficiency (>99.9 % over 5000 cycles) in KOH when used as an electrode. Notably, in a two-electrode symmetric supercapacitor, NPGC energy densities as high as 8.1 and 47.5 Wh kg(-1) , at a high power density (10.5 kW kg(-1) ), were achieved in 6 M KOH and 1 M Et4 NBF4 -PC electrolytes, respectively. Thus, the synthesized NPGC material could be a highly promising electrode material for advanced supercapacitors and other conversion devices. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of melamine in animal feed based on liquid chromatography tandem mass spectrometry analysis and dynamic microwave-assisted extraction coupled on-line with strong cation-exchange resin clean-up.

PubMed

Chen, Ligang; Zeng, Qinglei; Du, Xiaobo; Sun, Xin; Zhang, Xiaopan; Xu, Yang; Yu, Aimin; Zhang, Hanqi; Ding, Lan

2009-11-01

In this work, a new method was developed for the determination of melamine (MEL) in animal feed. The method was based on the on-line coupling of dynamic microwave-assisted extraction (DMAE) to strong cation-exchange (SCX) resin clean-up. The MEL was first extracted by 90% acidified methanol aqueous solution (v/v, pH = 3) under the action of microwave energy, and then the extract was cooled and passed through the SCX resin. Thus, the protonated MEL was retained on the resin through ion exchange interaction and the sample matrixes were washed out. Some obvious benefits were achieved, such as acceleration of analytical process, together with reduction in manual handling, risk of contamination, loss of analyte, and sample consumption. Finally, the analyte was separated by a liquid chromatograph with a SCX analytical column, and then identified and quantitatived by a tandem mass spectrometry with positive ionization mode and multiple-reaction monitoring. The DMAE parameters were optimized by the Box-Behnken design. The linearity of quantification obtained by analyzing matrix-matched standards is in the range of 50-5,000 ng g(-1). The limit of detection and limit of quantification obtained are 12.3 and 41.0 ng g(-1), respectively. The mean intra- and inter-day precisions expressed as relative standard deviations with three fortified levels (50, 250, and 500 ng g(-1)) are 5.1% and 7.3%, respectively, and the recoveries of MEL are in the range of 76.1-93.5%. The proposed method was successfully applied to determine MEL in different animal feeds obtained from the local market. MEL was detectable with the contents of 279, 136, and 742 ng g(-1) in three samples.

Supramolecularly engineered perylene bisimide assemblies exhibiting thermal transition from columnar to multilamellar structures.

PubMed

Yagai, Shiki; Usui, Mari; Seki, Tomohiro; Murayama, Haruno; Kikkawa, Yoshihiro; Uemura, Shinobu; Karatsu, Takashi; Kitamura, Akihide; Asano, Atsushi; Seki, Shu

2012-05-09

Perylene 3,4:9,10-tetracarboxylic acid bisimide (PBI) was functionalized with ditopic cyanuric acid to organize it into complex columnar architectures through the formation of hydrogen-bonded supermacrocycles (rosette) by complexing with ditopic melamines possessing solubilizing alkoxyphenyl substituents. The aggregation study in solution using UV-vis and NMR spectroscopies showed the formation of extended aggregates through hydrogen-bonding and π-π stacking interactions. The cylindrical fibrillar nanostructures were visualized by microscopic techniques (AFM, TEM), and the formation of lyotropic mesophase was confirmed by polarized optical microscopy and SEM. X-ray diffraction study revealed that a well-defined hexagonal columnar (Col(h)) structure was formed by solution-casting of fibrillar assemblies. All of these results are consistent with the formation of hydrogen-bonded PBI rosettes that spontaneously organize into the Col(h) structure. Upon heating the Col(h) structure in the bulk state, a structural transition to a highly ordered lamellar (Lam) structure was observed by variable-temperature X-ray diffraction, differential scanning calorimetry, and AFM studies. IR study showed that the rearrangement of the hydrogen-bonding motifs occurs during the structural transition. These results suggest that such a striking structural transition is aided by the reorganization in the lowest level of self-organization, i.e., the rearrangement of hydrogen-bonded motifs from rosette to linear tape. A remarkable increase in the transient photoconductivity was observed by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements upon converting the Col(h) structure to the Lam structure. Transient absorption spectroscopy revealed that electron transfer from electron-donating alkoxyphenyl groups of melamine components to electron-deficient PBI moieties takes place, resulting in a higher probability of charge carrier generation in the Lam structure compared to the Col(h) structure.

Comparison of sensitivity to artificial spectral errors and multivariate LOD in NIR spectroscopy - Determining the performance of miniaturizations on melamine in milk powder.

PubMed

Henn, Raphael; Kirchler, Christian G; Grossgut, Maria-Elisabeth; Huck, Christian W

2017-05-01

This study compared three commercially available spectrometers - whereas two of them were miniaturized - in terms of prediction ability of melamine in milk powder (infant formula). Therefore all spectra were split into calibration- and validation-set using Kennard Stone and Duplex algorithm in comparison. For each instrument the three best performing PLSR models were constructed using SNV and Savitzky Golay derivatives. The best RMSEP values were 0.28g/100g, 0.33g/100g and 0.27g/100g for the NIRFlex N-500, the microPHAZIR and the microNIR2200 respectively. Furthermore the multivariate LOD interval [LOD min , LOD max ] was calculated for all the PLSR models unveiling significant differences among the spectrometers showing values of 0.20g/100g - 0.27g/100g, 0.28g/100g - 0.54g/100g and 0.44g/100g - 1.01g/100g for the NIRFlex N-500, the microPHAZIR and the microNIR2200 respectively. To assess the robustness of all models, artificial introduction of white noise, baseline shift, multiplicative effect, spectral shrink and stretch, stray light and spectral shift were applied. Monitoring the RMSEP as function of the perturbation gave indication of robustness of the models and helped to compare the performances of the spectrometers. Not taking the additional information from the LOD calculations into account one could falsely assume that all the spectrometers perform equally well which is not the case when the multivariate evaluation and robustness data were considered. Copyright © 2017 Elsevier B.V. All rights reserved.

Blended polybenzimidazole and melamine-co-formaldehyde thermosets

DOE PAGES

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

2016-05-11

Polybenzimidazole [PBI; poly-2,2’(m-phenylene)-5,5’-bibenzimidazole] is known to have excellent high temperature stability (up to 450 ºC) and superb H 2/CO 2 selectivity compared to most high performance (HP) polymers. But, PBI has issues in thin-film formation compared to other HP polymers, due to challenging processing techniques. In this work, new blended thermosets were made with PBI and poly(melamine co-formaldehyde) [PMF] to produce stable thin-films after thermal processing at 220-250 ºC. PBI film formation is difficult, and the film tends to fracture and fissure due to loss of processing aids and stabilizers (salt/acid additives) that are found in PBI solutions above10 wtmore » %. The PBI-PMF blended thermosets we report do not have stabilizers, and can be made into dense thin-films. It is remarkable that these thermally processed PBI-PMF films were stable in deionized water for extended periods, whereas many PBI films that contain additives are not. The PBI-PMF films were analyzed using pure and mixed gas permeability measurement techniques. At 250 °C, the data show H 2/CO 2 gas selectivities greater than 13. Also, from the gas permeation data, the energy of activation (Ep) of a mixed gas stream for PBI-PMF shows that hydrogen permeates more easily than the other gases, while the permeabilities for the larger kinetic diameter gases are greatly diminished. The FT-IR spectra show that the PBI-PMF films have changed from parent PBI after thermal processing, and PMF dominates the spectra even in minor percent compositions. Altogether, the reported PBI-PMF thermoset films show good stability which can be used for high temperature gas separation.« less

Raman Analysis of Dilute Aqueous Samples by Localized Evaporation of Submicroliter Droplets on the Tips of Superhydrophobic Copper Wires.

PubMed

Cheung, Melody; Lee, Wendy W Y; McCracken, John N; Larmour, Iain A; Brennan, Steven; Bell, Steven E J

2016-04-19

Raman analysis of dilute aqueous solutions is normally prevented by their low signal levels. A very general method to increase the concentration to detectable levels is to evaporate droplets of the sample to dryness, creating solid deposits which are then Raman probed. Here, superhydrophobic (SHP) wires with hydrophilic tips have been used as supports for drying droplets, which have the advantage that the residue is automatically deposited at the tip. The SHP wires were readily prepared in minutes using electroless galvanic deposition of Ag onto copper wires followed by modification with a polyfluorothiol (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decanethiol, HDFT). Cutting the coated wires with a scalpel revealed hydrophilic tips which could support droplets whose maximum size was determined by the wire diameter. Typically, 230 μm wires were used to support 0.6 μL droplets. Evaporation of dilute melamine droplets gave solid deposits which could be observed by scanning electron microscopy (SEM) and Raman spectroscopy. The limit of detection for melamine using a two stage evaporation procedure was 1 × 10(-6) mol dm(-3). The physical appearance of dried droplets of sucrose and glucose showed that the samples retained significant amounts of water, even under high vacuum. Nonetheless, the Raman detection limits of sucrose and glucose were 5 × 10(-4) and 2.5 × 10(-3) mol dm(-3), respectively, which is similar to the sensitivity reported for surface-enhanced Raman spectroscopy (SERS) detection of glucose. It was also possible to quantify the two sugars in mixtures at concentrations which were similar to those found in human blood through multivariate analysis.

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

NASA Astrophysics Data System (ADS)

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.

A survey on trace organic chemicals in a German water protection area and the proposal of relevant indicators for anthropogenic influences.

PubMed

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.

Blended polybenzimidazole and melamine-co-formaldehyde thermosets

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Polybenzimidazole [PBI; poly-2,2’(m-phenylene)-5,5’-bibenzimidazole] is known to have excellent high temperature stability (up to 450 ºC) and superb H 2/CO 2 selectivity compared to most high performance (HP) polymers. But, PBI has issues in thin-film formation compared to other HP polymers, due to challenging processing techniques. In this work, new blended thermosets were made with PBI and poly(melamine co-formaldehyde) [PMF] to produce stable thin-films after thermal processing at 220-250 ºC. PBI film formation is difficult, and the film tends to fracture and fissure due to loss of processing aids and stabilizers (salt/acid additives) that are found in PBI solutions above10 wtmore » %. The PBI-PMF blended thermosets we report do not have stabilizers, and can be made into dense thin-films. It is remarkable that these thermally processed PBI-PMF films were stable in deionized water for extended periods, whereas many PBI films that contain additives are not. The PBI-PMF films were analyzed using pure and mixed gas permeability measurement techniques. At 250 °C, the data show H 2/CO 2 gas selectivities greater than 13. Also, from the gas permeation data, the energy of activation (Ep) of a mixed gas stream for PBI-PMF shows that hydrogen permeates more easily than the other gases, while the permeabilities for the larger kinetic diameter gases are greatly diminished. The FT-IR spectra show that the PBI-PMF films have changed from parent PBI after thermal processing, and PMF dominates the spectra even in minor percent compositions. Altogether, the reported PBI-PMF thermoset films show good stability which can be used for high temperature gas separation.« less

Rapid calibrated high-resolution hyperspectral imaging using tunable laser source

NASA Astrophysics Data System (ADS)

Nguyen, Lam K.; Margalith, Eli

2009-05-01

We present a novel hyperspectral imaging technique based on tunable laser technology. By replacing the broadband source and tunable filters of a typical NIR imaging instrument, several advantages are realized, including: high spectral resolution, highly variable field-of-views, fast scan-rates, high signal-to-noise ratio, and the ability to use optical fiber for efficient and flexible sample illumination. With this technique, high-resolution, calibrated hyperspectral images over the NIR range can be acquired in seconds. The performance of system features will be demonstrated on two example applications: detecting melamine contamination in wheat gluten and separating bovine protein from wheat protein in cattle feed.

Bioenabled SERS Substrates for Food Safety and Drinking Water Monitoring.

PubMed

Yang, Jing; Rorrer, Gregory L; Wang, Alan X

2015-04-20

We present low-cost bioenabled surface-enhanced Raman scattering (SERS) substrates that can be massively produced in sustainable and eco-friendly methods with significant commercial potentials for the detection of food contamination and drinking water pollution. The sensors are based on diatom frustules with integrated plasmonic nanoparticles. The ultra-high sensitivity of the SERS substrates comes from the coupling between the diatom frustules and Ag nanoparticles to achieve dramatically increased local optical field to enhance the light-matter interactions for SERS sensing. We successfully applied the bioenabled SERS substrates to detect melamine in milk and aromatic compounds in water with sensitivity down to 1μg/L.

Bioenabled SERS substrates for food safety and drinking water monitoring

NASA Astrophysics Data System (ADS)

Yang, Jing; Rorrer, Gregory L.; Wang, Alan X.

2015-05-01

We present low-cost bioenabled surface-enhanced Raman scattering (SERS) substrates that can be massively produced in sustainable and eco-friendly methods with significant commercial potentials for the detection of food contamination and drinking water pollution. The sensors are based on diatom frustules with integrated plasmonic nanoparticles. The ultra-high sensitivity of the SERS substrates comes from the coupling between the diatom frustules and Ag nanoparticles to achieve dramatically increased local optical field to enhance the light-matter interactions for SERS sensing. We successfully applied the bioenabled SERS substrates to detect melamine in milk and aromatic compounds in water with sensitivity down to 1μg/L.

Preparation of boron nitride fiber by organic precursor method

NASA Astrophysics Data System (ADS)

Zhou, Yingying; Sun, Runjun; Zhang, Zhaohuan; Fan, Wei; Zhou, Dan; Sheng, Cuihong

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.

Capillary electrophoresis for the analysis of contaminants in emerging food safety issues and food traceability.

PubMed

Vallejo-Cordoba, Belinda; González-Córdova, Aarón F

2010-07-01

This review presents an overview of the applicability of CE in the analysis of chemical and biological contaminants involved in emerging food safety issues. Additionally, CE-based genetic analyzers' usefulness as a unique tool in food traceability verification systems was presented. First, analytical approaches for the determination of melamine and specific food allergens in different foods were discussed. Second, natural toxin analysis by CE was updated from the last review reported in 2008. Finally, the analysis of prion proteins associated with the "mad cow" crises and the application of CE-based genetic analyzers for meat traceability were summarized.

Bioenabled SERS Substrates for Food Safety and Drinking Water Monitoring

PubMed Central

Yang, Jing; Rorrer, Gregory L.; Wang, Alan X.

2016-01-01

We present low-cost bioenabled surface-enhanced Raman scattering (SERS) substrates that can be massively produced in sustainable and eco-friendly methods with significant commercial potentials for the detection of food contamination and drinking water pollution. The sensors are based on diatom frustules with integrated plasmonic nanoparticles. The ultra-high sensitivity of the SERS substrates comes from the coupling between the diatom frustules and Ag nanoparticles to achieve dramatically increased local optical field to enhance the light-matter interactions for SERS sensing. We successfully applied the bioenabled SERS substrates to detect melamine in milk and aromatic compounds in water with sensitivity down to 1μg/L. PMID:26900205

High performance SERS on nanoporous gold substrates synthesized by chemical de-alloying a Au-based metallic glass

NASA Astrophysics Data System (ADS)

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.

Ultralight Fe@C Nanocapsules/Sponge Composite with Reversibly Tunable Microwave Absorption Performances.

PubMed

Li, Yixing; Mao, Zhe; Liu, Rongge; Zhao, Xiaoning; Zhang, Yanhui; Qin, Gaowu; Zhang, Xuefeng

2017-08-11

Microwave absorbers are usually designed to solve electromagnetic interferences at a specific frequency, while the requirements may be dynamic during service life. Therefore, a recoverable tuning for microwave absorption properties in response to an external stimulus would be highly desirable. We herein present a micro/nano-scale hybrid absorber, in which high-performance Fe@C nanocapsule absorbents are integrated with a porous melamine sponge skeleton, exhibiting multiple merits of light weight, strong absorption and high elasticity. By mechanically compressing and decompressing the absorber, microwave absorption performances can be effectively shifted between 18 GHz and 26.5 GHz. The present study thus provides a new strategy for the design of a 'dynamic' microwave absorber.

Ultralight Fe@C Nanocapsules/Sponge Composite with Reversibly Tunable Microwave Absorption Performances

NASA Astrophysics Data System (ADS)

Li, Yixing; Mao, Zhe; Liu, Rongge; Zhao, Xiaoning; Zhang, Yanhui; Qin, Gaowu; Zhang, Xuefeng

2017-08-01

Microwave absorbers are usually designed to solve electromagnetic interferences at a specific frequency, while the requirements may be dynamic during service life. Therefore, a recoverable tuning for microwave absorption properties in response to an external stimulus would be highly desirable. We herein present a micro/nano-scale hybrid absorber, in which high-performance Fe@C nanocapsule absorbents are integrated with a porous melamine sponge skeleton, exhibiting multiple merits of light weight, strong absorption and high elasticity. By mechanically compressing and decompressing the absorber, microwave absorption performances can be effectively shifted between 18 GHz and 26.5 GHz. The present study thus provides a new strategy for the design of a ‘dynamic’ microwave absorber.

Analysis of the stiffness and load-bearing capacity of glued laminated timber beams reinforced with strands

NASA Astrophysics Data System (ADS)

Sardiko, R.; Rocens, K.; Iejavs, J.; Jakovlevs, V.; Ziverts, K.

2017-10-01

In this paper a benefit of glulam pinewood beams reinforced strands is discussed. In the first phase, series of pull-out tests were performed on specimens made up of different types of glue (melamine-urea-formaldehyde, epoxy and others) to detect pull-out force and failure mode of a specimens. In the second phase, series of equal cross-section glulam beams with strand and rod reinforcement were theoretically analysed using transformed cross-section method. Additionally, series of experimental testing were made. Benefits of strand reinforcement use as glulam beams’ reinforcement were identified and examined the possibility of one glue type application in all operations of reinforced glulam beams manufacturing.

Laser-induced rocket force on a microparticle in a complex (dusty) plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nosenko, V.; Ivlev, A. V.; Morfill, G. E.

2010-12-15

The interaction of a focused powerful laser beam with micron-sized melamine formaldehyde (MF) particles was studied experimentally. The microspheres had a thin palladium coating on their surface and were suspended in a radio frequency argon plasma as a single layer (plasma crystal). A particle hit by the laser beam usually accelerated in the direction of the laser beam, consistent with the radiation pressure force mechanism. However, random-direction acceleration up to the speeds on the order 1 m/s was sometimes observed. Rocket-force mechanism is proposed to account for the random-direction acceleration. Similar, but much less pronounced, effect was also observed formore » MF particles without palladium coating.« less

Evaluation of super-water reducers for highway applications

NASA Astrophysics Data System (ADS)

Whiting, D.

1981-03-01

Super-water reducers were characterized and evaluated as potential candidates for production of low water to cement ratio, high strength concretes for highway construction applications. Admixtures were composed of either naphthalene or melamine sulfonated formaldehyde condensates. A mini-slump procedure was used to assess dosage requirements and behavior of workability with time of cement pastes. Required dosage was found to be a function of tricalcium aluminate content, alkali content, and fineness of the cement. Concretes exhibited high rates of slump loss when super-water reducers were used. The most promising area of application of these products appears to be in production of dense, high cement content concrete using mobile concrete mixer/transporters.

Genetic tests in mice of caffeine alone and in combination with mutagens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thayer, P.S.; Kensler, C.J.

1973-06-01

The possible mutagenicity of caffeine was studied in mice by the dominant-lethal method, in three experiments. Male mice were given caffeine in drinking water for 8 weeks at 3.6, 13.4, 49, and 122 mg/kg/day (comparable to human consumption of 2.8 to 95 cups of coffee per day). Subsequent mating of each of six males from each group to five females per week for 8 weeks showed no significant increase in dominant-lethal mutations (embryonic deaths) whether expressed as early deaths per pregnant female or as mutation index. Although males consuming the two higher levels of caffeine produced fewer pregnancies, litter sizesmore » of females giving birth were not reduced. Single ip injections of caffeine (15 mg/kg) were given to groups of male mice prior to, subsequent to, and immediately at the time of receiving x-rays (100 R). Each of five males from each group was mated to five females per week for 7 weeks. Embryonic deaths did not show any enhancing effect of caffeine on the mutagenicity produced by the irradiation. Three groups of male mice ingested caffeine in water for 16 weeks at levels of 0, 4, and 13 mg/kg/day. Subgroups of five from each group were given either: no further treatment, a single dose of triethylene melamine at 0.2 mg/kg, or 100 R of x ray, and mated for 7 weeks as above. Fertility and litter size were not affected by the caffeine pretreatment, nor did it modify the induction of dominant-lethal mutations by triethylene melamine or x rays. Litter sizes showed no significant preimplantation losses in any experiment. Thus, under the conditions described herein and at the doses employed (higher than human exposure), there was no evidence for the mutagenicity of caffeine or the inhibition of DNA repair mechanisms in these mammalian systems. (auth)« less

Hierarchical Honeycomb Br-, N-Codoped TiO2 with Enhanced Visible-Light Photocatalytic H2 Production.

PubMed

Zhang, Chao; Zhou, Yuming; Bao, Jiehua; Sheng, Xiaoli; Fang, Jiasheng; Zhao, Shuo; Zhang, Yiwei; Chen, Wenxia

2018-06-06

The halogen elements modification strategy of TiO 2 encounters a bottleneck in visible-light H 2 production. Herein, we have for the first time reported a hierarchical honeycomb Br-, N-codoped anatase TiO 2 catalyst (HM-Br,N/TiO 2 ) with enhanced visible-light photocatalytic H 2 production. During the synthesizing process, large amounts of meso-macroporous channels and TiO 2 nanosheets were fabricated in massive TiO 2 automatically, constructing the hierarchical honeycomb structure with large specific surface area (464 m 2 g -1 ). cetyl trimethylammonium bromide and melamine played a key role in constructing the meso-macroporous channels. Additionally, HM-Br,N/TiO 2 showed a high visible-light H 2 production rate of 2247 μmol h -1 g -1 , which is far more higher than single Br- or N-doped TiO 2 (0 or 63 μmol h -1 g -1 , respectively), thereby demonstrating the excellent synergistic effects of Br and N elements in H 2 evolution. In HM-Br,N/TiO 2 catalytic system, the codoped Br-N atoms could reduce the band gap of TiO 2 to 2.88 eV and the holes on acceptor levels (N acceptor) can passivate the electrons on donor levels (Br donor), thereby preventing charge carriers recombination significantly. Furthermore, the proposed HM-Br,N/TiO 2 fabrication strategy had a wide range of choices for N source (e.g., melamine, urea, and dicyandiamide) and it can be applied to other TiO 2 materials (e.g., P25) as well, thereby implying its great potential application in visible-light H 2 production. Finally, on the basis of experimental results, a possible photocatalytic H 2 production mechanism for HM-Br,N/TiO 2 was proposed.

Transparent SiO2-Ag core-satellite nanoparticle assembled layer for plasmonic-based chemical sensors

NASA Astrophysics Data System (ADS)

Chen, Tsung-Han; Jean, Ren-Der; Chiu, Kuo-Chuang; Chen, Chun-Hua; Liu, Dean-Mo

2012-05-01

We discovered a promising sensing capability of SiO2@Ag core-satellite nanoparticles with respect to organic melamine when they were consolidated into a solid-type thin-film entity. A series of theoretical models were proposed which provided calculation outcomes superior to those of existing models for the localized surface plasmon resonance spectra of the solid-state assemblies. We envisioned not only that such a SiO2@Ag film is a potential candidate for a transparent solid-state optical nanosensor for the detection of organic molecules but also that the resulting plasmonic resonance model facilitates a better understanding of such a solid-state nanosensor used for a number of sensory applications.

Facile Synthesis of Pre-Doping Lithium-Ion Into Nitrogen-Doped Graphite Negative Electrode for Lithium-Ion Capacitor.

PubMed

Lee, Seul-Yi; Kim, Ji-Il; Rhee, Kyong Yop; Park, Soo-Jin

2015-09-01

Nitrogen-doped graphite, prepared via the thermal decomposition of melamine into a carbon matrix for use as the negative electrode in lithium-ion capacitors (LICs), was evaluated by electrochemical measurements. Furthermore, in order to study the performance of pre-doped lithium components as a function of nitrogen-doped material, the pre-doped lithium graphite was allowed to react with a lithium salt solution. The results showed that the nitrogen functional groups in the graphite largely influenced the pre-doped lithium components, thereby contributing to the discharge capacity and cycling performance. We confirmed that the large initial irreversible capacity could be significantly decreased by using pre-doped lithium components obtained through the nitrogen-doping method.

Low emissions diesel fuel

DOEpatents

Compere, Alicia L.; Griffith, William L.; Dorsey, George F.; West, Brian H.

1998-01-01

A method and matter of composition for controlling NO.sub.x emissions from existing diesel engines. The method is achieved by adding a small amount of material to the diesel fuel to decrease the amount of NO.sub.x produced during combustion. Specifically, small amounts, less than about 1%, of urea or a triazine compound (methylol melamines) are added to diesel fuel. Because urea and triazine compounds are generally insoluble in diesel fuel, microemulsion technology is used to suspend or dissolve the urea or triazine compound in the diesel fuel. A typical fuel formulation includes 5% t-butyl alcohol, 4.5% water, 0.5% urea or triazine compound, 9% oleic acid, and 1% ethanolamine. The subject invention provides improved emissions in heavy diesel engines without the need for major modifications.

Low emissions diesel fuel

DOEpatents

Compere, A.L.; Griffith, W.L.; Dorsey, G.F.; West, B.H.

1998-05-05

A method and matter of composition for controlling NO{sub x} emissions from existing diesel engines. The method is achieved by adding a small amount of material to the diesel fuel to decrease the amount of NO{sub x} produced during combustion. Specifically, small amounts, less than about 1%, of urea or a triazine compound (methylol melamines) are added to diesel fuel. Because urea and triazine compounds are generally insoluble in diesel fuel, microemulsion technology is used to suspend or dissolve the urea or triazine compound in the diesel fuel. A typical fuel formulation includes 5% t-butyl alcohol, 4.5% water, 0.5% urea or triazine compound, 9% oleic acid, and 1% ethanolamine. The subject invention provides improved emissions in heavy diesel engines without the need for major modifications.

Solvent-induced synthesis of nitrogen-doped hollow carbon spheres with tunable surface morphology for supercapacitors

NASA Astrophysics Data System (ADS)

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.

Nitrogen-doped mesoporous carbon-armored cobalt nanoparticles as efficient hydrogen evolving electrocatalysts.

PubMed

Tang, Duihai; Li, Kuo; Zhang, Wenting; Qiao, Zhen-An; Zhu, Junjiang; Zhao, Zhen

2018-03-15

A series of Co nanoparticles embedded, N-doped mesoporous carbons have been synthesized through chelate-assisted co-assembly strategy followed by thermal treatment. The preparation is based on an assembly process, with evaporation of an ethanol-water solution containing melamine formaldehyde resin (MF resin) as carbon source, nitrogen source, and chelating agent. Moreover, F127 and Co(NO 3 ) 2 are used as template and metallic precursor, respectively. The Co nanoparticles embedded, N-doped mesoporous carbon annealed at 800 °C (denoted as MFCo800) shows high electrocatalytic activity for hydrogen evolution reaction (HER) with high current density and low overpotential, which has the ability to operate in both acidic and alkaline electrolytes. Copyright © 2017. Published by Elsevier Inc.

Dose—response relationships for agents inhibiting the immune response

PubMed Central

Berenbaum, M. C.; Brown, I. N.

1964-01-01

Mice were injected with T.A.B. vaccine and, 2 days later, with various doses of different compounds. The relation between dose of compound, mortality and antibody production was studied, and therapeutic indices were calculated for a number of compounds. The most effective agent in suppressing antibody production at relatively non-toxic doses was cyclophosphamide, with next amethopterin (the effect of which was, however, inexplicably erratic), 6-thioguanine and 6-mercaptopurine, in that order. Vincaleukoblastine, triethylene melamine, triethylenethiophosphoramide, mannomustine and 5-fluorouracil were less effective. Compounds of a miscellaneous group (boric acid, caffeine, sodium nitrite, bacitracin, neomycin and polymyxin `B') were studied in the same way: they had no effect on antibody production, even in lethal doses. PMID:14113077

Development of new addition-type composite resins

NASA Technical Reports Server (NTRS)

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.

Recent advances in chemical imaging technology for the detection of contaminants for food safety and security

NASA Astrophysics Data System (ADS)

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.

[Etiology of combined inhalational hydrocyanic acid and carbon monoxide poisoning].

PubMed

Sigrist, T; Dirnhofer, R

1979-01-01

A young man was found dead in a kitchen, that was partly burnt. Autopsy revealed, as cause of death, a combined intoxication following inhalation of carbon monoxide and hydrocyanic acid. Own investigations on the pyrolysis of pieces of furniture found in the kitchen (plastic plates containing melamine and plates containing formaldehyde) showed, that hydrocyanic acid was liberated through combustion of such substances and inhaled by the victim. The poisoning picture is discussed, and discussion includes especially considerations on the peculiar sensitivity of the brain toward the action of hydrocyanic acid and the relative insensitivity of the heart muscle. It is thought that the cause of such sensitivity difference lies in the physiological differences of the intracellular energy production. Finally the dangers of combustion gases developing from burning plastic materials are reemphasized.

Prediction of calcium level in melamine-related urinary calculi with helical CT: diagnostic performance evaluation and clinical significance.

PubMed

Yuan, Li; Xiaorui, Ru; Gang, Huang; Xinsheng, Xi; Xiaogang, Huang; Li, Dong; Yirong, Chen

2012-06-01

The aim of the study was to investigate the relationship between CT-attenuation and stone calcium level in melamine-related urinary calculi (MRUC). A total of 25 MRUC with known composition and calcium level were included (11 uric acid stones, 2 calcium oxalate stones and 12 mixture stones of uric acid and calcium oxalate). Of all, 18 renal stones accepted alkalization therapy except for 5 lower urinary tract stones and 2 stones of unknown position. With well-matched composition, 61 adult urinary stones were included as controls. Every stone was scanned by helical CT (80 kV/120 kV, 300 mA, pitch 0.625 mm) and the highest CT-attenuation value measured. CT-attenuation values of MRUC increased gradually from uric acid stones, mixture stones to calcium oxalate stones, but were always lower than the values of controls. Furthermore, a strong positive correlation was found between stone CT-attenuation value and stone calcium level (n = 25, r (80kV) = 0.883, p = 0.000; r (120kV) = 0.855, p = 0.000). Compared with alkalization-therapy-alone group, stone CT-attenuation values and stone calcium level in the comprehensive-therapy group were significantly greater (CT(80kV) 1,057 ± 639 vs. 172 ± 61 HU, p = 0.001; CT(120kV) 783 ± 476 vs. 162 ± 60 HU, p = 0.001; Ca 19.83 ± 7.48% vs. 1.30 ± 1.51%, p = 0.000). Fisher's exact test suggested that the stones with higher CT-attenuation values tended to resist alkalization when 400 HU served as the cutoff value (P (80kV) = 0.002, P (120kV) = 0.000). In conclusion, the study was the first to illustrate that the CT-attenuation value could reflect calcium level in MRUC and found that stones with higher CT-attenuation value were not amenable to alkalization because they probably contained greater calcium. For those patients, we believe that comprehensive therapy will be the best choice.

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

PubMed

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.

Novel antimicrobial textiles

NASA Astrophysics Data System (ADS)

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 (SAP) by copolymerization of hydantoin containing monomer and acrylic acid and coating of SAP onto filter fabrics, and (9) use of a hindered amine compound to treat fabrics for use as air filters. Some treated samples were subjected to laundry testing and aging testing for evaluating their durabilities. Bacterial testing was performed to determine the antimicrobial efficacies of the samples. The results demonstrated that many of the treated samples exhibited promising antibacterial effectiveness.

Surface-modified multifunctional MIP nanoparticles

NASA Astrophysics Data System (ADS)

Moczko, Ewa; Poma, Alessandro; Guerreiro, Antonio; Perez de Vargas Sansalvador, Isabel; Caygill, Sarah; Canfarotta, Francesco; Whitcombe, Michael J.; Piletsky, Sergey

2013-04-01

The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinylferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors.The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinylferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors. Electronic supplementary information (ESI) available: Details of the synthesis of eosin O-acrylate monomer and 1H-NMR spectrum of MIP NPs post-derivatised with PEG shell. See DOI: 10.1039/c3nr00354j

Vertically aligned BCN nanotubes with high capacitance.

PubMed

Iyyamperumal, Eswaramoorthi; Wang, Shuangyin; Dai, Liming

2012-06-26

Using a chemical vapor deposition method, we have synthesized vertically aligned BCN nanotubes (VA-BCNs) on a Ni-Fe-coated SiO(2)/Si substrate from a melamine diborate precursor. The effects of pyrolysis conditions on the morphology and thermal property of grown nanotubes, as well as the nanostructure and composition of an individual BCN nanotube, were systematically studied. It was found that nitrogen atoms are bonded to carbons in both graphitic and pyridinic forms and that the resultant VA-BCNs grown at 1000 °C show the highest specific capacitance (321.0 F/g) with an excellent rate capability and high durability with respect to nonaligned BCN (167.3 F/g) and undoped multiwalled carbon nanotubes (117.3 F/g) due to synergetic effects arising from the combined co-doping of B and N in CNTs and the well-aligned nanotube structure.

Covalent organic framework-derived microporous carbon nanoparticles coated with conducting polypyrrole as an electrochemical capacitor

NASA Astrophysics Data System (ADS)

Kim, Dong Jun; Yoon, Jung Woon; Lee, Chang Soo; Bae, Youn-Sang; Kim, Jong Hak

2018-05-01

We report a high-performance electrochemical capacitor based on covalent organic framework (COF)-derived microporous carbon (MPC) nanoparticles and electrochemically polymerized polypyrrole (Ppy) as a pseudocapacitive material. The COF, Schiff-based network-1 (SNW-1) nanoparticles are prepared via a condensation reaction between melamine and terephthalaldehyde, and the resultant MPC film is prepared via a screen-printing method. The MPC film exhibits a bimodal porous structure with micropores and macropores, resulting in both a large surface area and good electrolyte infiltration. Ppy is synthesized potentio-statically (0.8 V vs. Ag/AgCl) by varying the reaction time, and successful synthesis of Ppy is confirmed via Raman spectroscopy. The specific capacitance with the Ppy coating is enhanced by up to 2.55 F cm-2 due to the synergetic effect of pseudocapacitance and reduced resistance.

Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma.

PubMed

Yousefi, Razieh; Davis, Allen B; Carmona-Reyes, Jorge; Matthews, Lorin S; Hyde, Truell W

2014-09-01

Understanding the agglomeration of dust particles in complex plasmas requires knowledge of basic properties such as the net electrostatic charge and dipole moment of the dust. In this study, dust aggregates are formed from gold-coated mono-disperse spherical melamine-formaldehyde monomers in a radiofrequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining three-dimensional structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, as well as the external electric field, to be determined. It is shown that the experimental results support the predicted values from computer models for aggregates in these environments.

Enhanced ion signals in desorption electrospray ionization using surfactant spray solutions.

PubMed

Badu-Tawiah, Abraham; Cooks, R Graham

2010-08-01

Solvent optimization is an important procedure in desorption electrospray ionization (DESI) and in this study the effects of solvent surface tension are explored. Data are presented for methanol/water/surfactant solvent systems, which show increases in ion signals of more than an order of magnitude when low concentrations of surfactants are added to the standard methanol/water (1:1) spray solvent. Examples of analytes tested include food chemicals, peptides, pharmaceuticals, and drugs of abuse. The improvement in ion intensity is mainly attributed to the effect of surface tension in producing smaller spray droplets, which are shown to cover a larger surface area. Surfactant-containing spray solutions allowed extension of DESI-MS analysis to previously intractable analytes like melamine and highly hydrophobic compounds like the sudan dyes. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Effect of pH on the adsorption and photocatalytic degradation of sulfadimidine in Vis/g-C3N4 progress.

PubMed

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 .

Synthesis of reduced carbon nitride at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C3N4)O

NASA Astrophysics Data System (ADS)

Kharlamov, Alexey; Bondarenko, Marina; Kharlamova, Ganna; Fomenko, Veniamin

2016-09-01

For the first time at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C3N4)O reduced carbon nitride (or reduced multi-layer azagraphene) is obtained. It is differed from usually synthesized carbon nitride by a significantly large (on 0.09 nm) interplanar distance is. At the same time, the chemical bonds between atoms in a heteroatomic plane of reduced carbon nitride correspond to the bonds in a synthesized g-C3N4. The samples of water-soluble carbon nitride oxide were synthesized under the special reactionary conditions of a pyrolysis of melamine and urea. We believe that reduced carbon nitride consists of weakly connected carbon-nitrogen monosheets (azagraphene sheets) as well as reduced (from graphene oxide) graphene contains weakly connected graphene sheets.

Structural insights into photocatalytic performance of carbon nitrides for degradation of organic pollutants

NASA Astrophysics Data System (ADS)

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.

Surface-enhanced Raman spectroscopy applied to food safety.

PubMed

Craig, Ana Paula; Franca, Adriana S; Irudayaraj, Joseph

2013-01-01

Surface-enhanced Raman spectroscopy (SERS) is an advanced Raman technique that enhances the vibrational spectrum of molecules adsorbed on or in the vicinity of metal particles and/or surfaces. Because of its readiness, sensitivity, and minimum sample preparation requirements, SERS is being considered as a powerful technique for food inspection. Key aspects of food-safety assurance, spectroscopy methods, and SERS are briefly discussed in an extended introduction of this review. The recent and potential advances in SERS are highlighted in sections that deal with the (a) detection of food-borne pathogenic microorganisms and (b) the detection of food contaminants and adulteration, concentrated specifically on antibiotics, drugs, hormones, melamine, and pesticides. This review provides an outlook of the work done and a perspective on the future directions of SERS as a reliable tool for food-safety assessment.

Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Gilwee, W. J., Jr.; Parker, J. A.

1979-01-01

The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated include polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated include epoxy, bismaleimide, a modified phenolic, and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass-reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented, and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

U. S. plastics demand drops sharply

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

According to the Society of the Plastics Industry, plastics demand dropped sharply in the U.S. during second-quarter 1980. U.S. exports of themoplastics are down slightly from year-ago levels, and PVC and low-density polyethylene (LDPE) exports are increasing strongly, but strong exports can not offset a weak domestic market. The weakness in domestic PVC sales is due mostly to large drops in contruction pipe (-49%) and automotive uses, its leading markets, in the last year. LDPE sales have dropped 3% over the year, and 8% in film, LPDE's largest market. Polypropylene's two largest U.S. markets, molding and fibers, have also droppedmore » sharply. Epoxy resin showed a May 1979 to May 1980 gain of 28% in exports, but three other thermosets, polyesters, urea-melamine, and phenolics, have dropped sharply since May 1979.« less

Characterization of cells and bacteria by photophoretic velocimetry

NASA Astrophysics Data System (ADS)

Helmbrecht, Clemens; Niessner, Reinhard; Haisch, Christoph

2008-02-01

The migration induced by intensive light is termed photophoresis. We could show that the evaluation of light-induced velocities of microparticles, bacteria and cells suspended in water is valuable for the prediction of their intrinsic properties. Two different laser setups were evaluated for photophoretic migration, a He-Ne laser (P = 45 mW, λ = 633 nm) and a diode-pumped cw-Nd:YAG (P = 1.1 W, λ = 532 nm). When analyzing the migration behavior of particles, we find significant differences depending on both, geometrical size and refractive index. We describe migration of PS particles of different size as well as with different refractive index but same diameter, SiO II and melamine resin. The potential for the separation of biological matter is shown as velocity distributions of heat killed bacteria of Escherichia coli, Salmonella enteritidis, and baker's yeast is reported.

Nitrogen-doped carbon coated silicon derived from a facile strategy with enhanced performance for lithium storage

NASA Astrophysics Data System (ADS)

Zeng, Lingxing; Liu, Renpin; Qiu, Heyuan; Chen, Xi; Huang, Xiaoxia; Xiong, Peixun; Qian, Qingrong; Chen, Qinghua; Wei, Mingdeng

2016-07-01

Silicon-based nanostructures are receiving intense interest in lithium-ion batteries (LIBs) because they have ultrahigh lithium ion storage ability. However, the fast capacity fading induced by the considerably tremendous volume changes of Si anode during the Li-ion intercalation processes as well as the low intrinsic electric conductivity have hindered its deployment. Herein, we initially developed an effective technique to synthesize the core-shell Si/nitrogen-doped carbon (Si/N-C), composite by combining in situ interfacial polymerization and decorate with melamine, followed by carbonization. When used as anode material for LIBs, the Si/N-C composite delivered a notable reversible capacity (1084 mAh g-1 at 0.2 A g-1 for 50 cycles) and high rate capability (495 mAh g-1 at 1 A g-1).

Surface modification of polymeric foams for oil spills remediation.

PubMed

Pinto, Javier; Athanassiou, Athanassia; Fragouli, Despina

2018-01-15

In the last decade, a continuous increasing research activity is focused on the surface functionalization of polymeric porous materials for the efficient removal of oil contaminants from water. This work reviews the most significant recent studies on the functionalization of polyurethane and melamine foams, materials commonly reported for oil-water separation applications. After the identification of the key features of the foams required to optimize their oil removal performance, a wide variety of physicochemical treatments are described together with their effect on the oil absorption selectivity and oil absorption capacity, both critical parameters for the application of the foams in the remediation of oil spills. The efficiencies of the different functionalization processes on the same type of foams are compared, determining the main advantages and potentialities of each treatment and remediation procedure. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Raman chemical imaging system for detection of contaminants in food

NASA Astrophysics Data System (ADS)

Chao, Kaunglin; Qin, Jianwei; Kim, Moon S.; Mo, Chang Yeon

2011-06-01

This study presented a preliminary investigation into the use of macro-scale Raman chemical imaging for the screening of dry milk powder for the presence of chemical contaminants. Melamine was mixed into dry milk at concentrations (w/w) of 0.2%, 0.5%, 1.0%, 2.0%, 5.0%, and 10.0% and images of the mixtures were analyzed by a spectral information divergence algorithm. Ammonium sulfate, dicyandiamide, and urea were each separately mixed into dry milk at concentrations of (w/w) of 0.5%, 1.0%, and 5.0%, and an algorithm based on self-modeling mixture analysis was applied to these sample images. The contaminants were successfully detected and the spatial distribution of the contaminants within the sample mixtures was visualized using these algorithms. Although further studies are necessary, macro-scale Raman chemical imaging shows promise for use in detecting contaminants in food ingredients and may also be useful for authentication of food ingredients.

Novel VN/C nanocomposites as methanol-tolerant oxygen reduction electrocatalyst in alkaline electrolyte

PubMed Central

Huang, K.; Bi, K.; Liang, C.; Lin, S.; Zhang, R.; Wang, W. J.; Tang, H. L.; Lei, M.

2015-01-01

A novel VN/C nanostructure consisting of VN nanoparticles and graphite-dominant carbon layers is synthesized by nitridation of V2O5 using melamine as reductant under inert atmosphere. High crystalline VN nanoparticles are observed to be uniformly distributed in carbon layers with an average size of ca13.45 nm. Moreover, the electrocatalytic performance of VN/C towards oxygen reduction reaction (ORR) in alkaline electrolyte is fascinating. The results show that VN/C has a considerable ORR activity, including a 75 percent value of the diffusion-limited current density and a 0.11 V smaller value about the onset potential with respect to Pt/C catalyst. Moreover, the excellent methanol-tolerance performance of VN/C has also been verified with 3 M methanol. Combined with the competitive prices, this VN/C nanocomposite can serve as an appropriate non-precious methanol-tolerant ORR catalyst for alkaline fuel cells. PMID:26100367

Quinol derivatives as potential trypanocidal agents

PubMed Central

Capes, Amy; Patterson, Stephen; Wyllie, Susan; Hallyburton, Irene; Collie, Iain T.; McCarroll, Andrew J.; Stevens, Malcolm F.G.; Frearson, Julie A.; Wyatt, Paul G.; Fairlamb, Alan H.; Gilbert, Ian H.

2012-01-01

Quinols have been developed as a class of potential anti-cancer compounds. They are thought to act as double Michael acceptors, forming two covalent bonds to their target protein(s). Quinols have also been shown to have activity against the parasite Trypanosoma brucei, the causative organism of human African trypanosomiasis, but they demonstrated little selectivity over mammalian MRC5 cells in a counter-screen. In this paper, we report screening of further examples of quinols against T. brucei. We were able to derive an SAR, but the compounds demonstrated little selectivity over MRC5 cells. In an approach to increase selectivity, we attached melamine and benzamidine motifs to the quinols, because these moieties are known to be selectively concentrated in the parasite by transporter proteins. In general these transporter motif-containing analogues showed increased selectivity; however they also showed reduced levels of potency against T. brucei. PMID:22264753

Structural and electronic properties of extremely long perylene bisimide nanofibers formed through a stoichiometrically mismatched, hydrogen-bonded complexation.

PubMed

Yagai, Shiki; Seki, Tomohiro; Murayama, Haruno; Wakikawa, Yusuke; Ikoma, Tadaaki; Kikkawa, Yoshihiro; Karatsu, Takashi; Kitamura, Akihide; Honsho, Yoshihito; Seki, Shu

2010-12-06

Extremely long nanofibers, whose lengths reach the millimeter regime, are generated via co-aggregation of a melamine-appended perylene bisimide semiconductor and a substituted cyanurate, both of which are ditopic triple-hydrogen-bonding building blocks; they co-aggregate in an unexpected stoichiometrically mismatched 1:2 ratio. Various microscopic and X-ray diffraction studies suggest that hydrogen-bonded polymeric chains are formed along the long axis of the nanofibers by the 1:2 complexation of the two components, which further stack along the short axis of the nanofibers. The photocarrier generation mechanism in the nanofibers is investigated by time-of-flight (TOF) experiments under electric and magnetic fields, revealing the birth and efficient recombination of singlet geminate electron-hole pairs. Flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements revealed intrinsic 1D electron mobilities up to 0.6 cm(2) V(-1) s(-1) within nanofibers.

Nitrogen-doped carbon spheres: A new high-energy-density and long-life pseudo-capacitive electrode material for electrochemical flow capacitor.

PubMed

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.

Investigation of automotive primer and basecoat paint surface's adhesion by solid particle erosion

NASA Astrophysics Data System (ADS)

Demirci, M.; Baǧcı, M.

2018-05-01

Millions of cars are sold around the world and tons of paint are used for these cars. Since the car paint industry is alive in this way, new developments in the paint sector have been taking place every day. It is important to determine how these developments affect paint erosion. Solid particle erosion wear is a subject that keeps its update for car paints and it always needs to be investigated in detail. The target of this experimental study is to investigate solid particle erosion behavior of a commercial acrylic/melamine primer surface and basecoat of automotive paint. As a erodent, silica particles having a weight of 1 to 5 kg were used. Tests were performed at 30° and 90° impact angle and particle velocity 23 m s-1. With this work, an idea about the adhesion of the car paint coatings to the material surface was obtained.

Carbon paste electrode modified molecularly imprinted polymer as a sensor for creatinine analysis by stripping voltammetry

NASA Astrophysics Data System (ADS)

Khasanah, M.; Darmokoesoemo, H.; Rizki, D. A.

2017-09-01

Modification of carbon paste electrode with molecularly imprinted polymer (CP-MIP) as a voltammetric sensor for creatinine has been developed. MIP was synthesized by reacting melamine, chloranil and creatinine with a mole ratio of 1:1:0.1. Creatinine was extracted from polymer chain by using hot water to form a specific imprinted for creatinine molecule. Carbon paste-MIP electrode was prepared by mixing activated carbon, solid paraffin, and MIP in a 45:40:15(w/w %) ratio. The optimum conditions of creatinine analysis by differential pulse stripping voltammetry (DPSV) using the developed electrode were the accumulation potential -1000 mV during 90 s at pH 5. The precision of the method for 0.1-0.5 μlg/L creatinine was 88.7-96.3%, while the detection limit of this method was 0.0315 μlg/L. The accuracy compared by spectrophotometric method was 95.3-103.6%

Synthesis of metal free ultrathin graphitic carbon nitride sheet for photocatalytic dye degradation of Rhodamine B under visible light irradiation

NASA Astrophysics Data System (ADS)

Rahman, Shakeelur; Momin, Bilal; Higgins M., W.; Annapure, Uday S.; Jha, Neetu

2018-04-01

In recent times, low cost and metal free photocatalyts driven under visible light have attracted a lot of interest. One such photo catalyst researched extensively is bulk graphitic carbon nitride sheets. But the low surface area and weak mobility of photo generated electrons limits its photocatalytic performance in the visible light spectrum. Here we present the facile synthesis of ultrathin graphitic carbon nitride using a cost effective melamine precursor and its application in highly efficient photocatalytic dye degradation of Rhodamine B molecules. Compared to bulk graphitic carbon nitride, the synthesized ultrathin graphitic carbon nitride shows an increase in surface area, a a decrease in optical band gap and effective photogenerated charge separation which facilitates the harvest of visible light irradiation. Due to these optimal properties of ultrathin graphitic carbon nitride, it shows excellent photocatalytic activity with photocatalytic degradation of about 95% rhodamine B molecules in 1 hour.

Fireproofing and heat insulating performance improvement of EG/ATH modified intumescent flame retardant coating treated under Co-60 radiation

NASA Astrophysics Data System (ADS)

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.

Determination of the resistance of fabric printed with triclosan microcapsules to the action of soil micro-flora

NASA Astrophysics Data System (ADS)

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.

Characterization of flammability properties of some thermoplastic and thermoset resins. [for aircraft interiors

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.

1978-01-01

The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated included polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated included epoxy, bismaleimide, a modified phenolic and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

The direct and inverse problems of an air-saturated poroelastic cylinder submitted to acoustic radiation

NASA Astrophysics Data System (ADS)

Ogam, Erick; Fellah, Z. E. A.

2011-09-01

A wave-fluid saturated poroelastic structure interaction model based on the modified Biot theory (MBT) and plane-wave decomposition using orthogonal cylindrical functions is developed. The model is employed to recover from real data acquired in an anechoic chamber, the poromechanical properties of a soft cellular melamine cylinder submitted to an audible acoustic radiation. The inverse problem of acoustic diffraction is solved by constructing the objective functional given by the total square of the difference between predictions from the MBT interaction model and diffracted field data from experiment. The faculty of retrieval of the intrinsic poromechanical parameters from the diffracted acoustic fields, indicate that a wave initially propagating in a light fluid (air) medium, is able to carry in the absence of mechanical excitation of the specimen, information on the macroscopic mechanical properties which depend on the microstructural and intrinsic properties of the solid phase.

Adhesion of perfume-filled microcapsules to model fabric surfaces.

PubMed

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.

Surface-modified multifunctional MIP nanoparticles.

PubMed

Moczko, Ewa; Poma, Alessandro; Guerreiro, Antonio; Perez de Vargas Sansalvador, Isabel; Caygill, Sarah; Canfarotta, Francesco; Whitcombe, Michael J; Piletsky, Sergey

2013-05-07

The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinylferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors.

Erection of duct-like graphitic carbon nitride with enhanced photocatalytic activity for ACB photodegradation

NASA Astrophysics Data System (ADS)

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Ullah, Sami; Aziz, Hammad, E-mail: engr.hammad.aziz03@gmail.com

The results of influence of glass fiber addition into the basic intumescent coating formulation towards the enhancement of its thermal insulation properties are presented. The intumescent coatings were formulated from expandable graphite, ammonium polyphosphate, melamine, boric acid, bisphenol A epoxy resin BE-188, polyamide amine H-2310 hardener and fiberglass (FG) of length 3.0 mm. Eight intumescent formulations were developed and the samples were tested for their fire performance by burning them at 450°C, 650°C and 850°C in the furnace for two hours. The effects of each fire test at different temperatures; low and high temperature were evaluated. Scanning Electron Microscope, X-Ray Diffractionmore » technique and Thermo Gravimetric Analysis were conducted on the samples to study the morphology, the chemical components of char and the residual weight of the coatings. The formulation, FG08 containing 7.0 wt% glass fiber provided better results with enhanced thermal insulation properties of the coatings.« less

Novel VN/C nanocomposites as methanol-tolerant oxygen reduction electrocatalyst in alkaline electrolyte

NASA Astrophysics Data System (ADS)

Huang, K.; Bi, K.; Liang, C.; Lin, S.; Zhang, R.; Wang, W. J.; Tang, H. L.; Lei, M.

2015-06-01

A novel VN/C nanostructure consisting of VN nanoparticles and graphite-dominant carbon layers is synthesized by nitridation of V2O5 using melamine as reductant under inert atmosphere. High crystalline VN nanoparticles are observed to be uniformly distributed in carbon layers with an average size of ca13.45 nm. Moreover, the electrocatalytic performance of VN/C towards oxygen reduction reaction (ORR) in alkaline electrolyte is fascinating. The results show that VN/C has a considerable ORR activity, including a 75 percent value of the diffusion-limited current density and a 0.11 V smaller value about the onset potential with respect to Pt/C catalyst. Moreover, the excellent methanol-tolerance performance of VN/C has also been verified with 3 M methanol. Combined with the competitive prices, this VN/C nanocomposite can serve as an appropriate non-precious methanol-tolerant ORR catalyst for alkaline fuel cells.

Preparation, crystal structure, vibrational spectral and density functional studies of bis (4-nitrophenol)-2,4,6-triamino-1,3,5-triazine monohydrate

NASA Astrophysics Data System (ADS)

Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Renganathan, N. G.; Gunasekaran, S.; Anbalagan, G.

2013-10-01

An organic-organic salt, bis (4-nitrophenol) 2,4,6-triamino 1,3,5-triazine monohydrate (BNPM) has been prepared by slow evaporation technique at room temperature. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in triclinic system with centrosymmetric space group P-1. IR and Raman spectra of BNPM have been recorded and analyzed. The study has been extended to confocal Raman spectral analysis. Band assignments have been made for the melamine and p-nitrophenol molecules. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory calculations using Firefly (PC GAMESS) Version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with the experimental one. The Mulliken charges, HOMO-LUMO orbital energies are calculated and analyzed. The chemical structure of the compound was established by 1H NMR and 13C NMR spectra.

Structural and electronic properties of barbituric acid and melamine-containing ribonucleosides as plausible components of prebiotic RNA: implications for prebiotic self-assembly.

PubMed

Kaur, Sarabjeet; Sharma, Purshotam; Wetmore, Stacey D

2017-11-22

The RNA world hypothesis assumes that RNA was the first informational polymer that originated from prebiotic chemical soup. However, since the reaction of d-ribose with canonical nucleobases (A, C, G and U) fails to yield ribonucleosides (rNs) in substantial amounts, the spontaneous origin of rNs and the subsequent synthesis of RNA remains an unsolved mystery. To this end, it has been suggested that RNA may have evolved from primitive genetic material (preRNA) composed of simpler prebiotic heterocycles that spontaneously form glycosidic bonds with ribose. As an effort toward evaluating this hypothesis, the present study uses density functional theory (DFT) to assess the suitability of barbituric acid (BA) and melamine (MM) to act as prebiotic nucleobases, both of which have recently been shown to spontaneously form a glycosidic bond with ribose and organize into supramolecular assemblies in solution. The significant strength of hydrogen bonds involving BA and MM indicates that such interactions may have played a crucial role in their preferential selection over competing heterocycles that interact solely through stacking interactions from the primordial soup during the early phase of evolution. However, the greater stability of stacked dimers involving BA or MM and the canonical nucleobases compared to those consisting solely of BA and/or MM points towards the possible evolution of intermediate informational polymers consisting of prebiotic and canonical nucleobases, which could have eventually evolved into RNA. Analysis of the associated rNs reveals an anti conformational preference for the biologically-relevant β-anomer of both BA and MM rNs, which will allow complementary WC-like hydrogen bonding that can stabilize preRNA polymers. Large calculated deglycosylation barriers suggest BA rNs containing C-C glycosidic bonds are relevant in challenging prebiotic environments such as volcanic geotherms, while lower barriers indicate the MM rNs containing C-N-C glycosidic linkages may have been more likely synthesized from simple precursors such as urea-ice in icy (polar) regions. Together, our quantum chemical data clarifies the physicochemical interactions and stability of potential prebiotically-relevant constituents of BA and MM polymeric assemblies, and complements information from previous experimental studies to bolster the candidature of these heterocycles as prebiotic nucleobases.

Calibration model maintenance in melamine resin production: Integrating drift detection, smart sample selection and model adaptation.

PubMed

Nikzad-Langerodi, Ramin; Lughofer, Edwin; Cernuda, Carlos; Reischer, Thomas; Kantner, Wolfgang; Pawliczek, Marcin; Brandstetter, Markus

2018-07-12

The physico-chemical properties of Melamine Formaldehyde (MF) based thermosets are largely influenced by the degree of polymerization (DP) in the underlying resin. On-line supervision of the turbidity point by means of vibrational spectroscopy has recently emerged as a promising technique to monitor the DP of MF resins. However, spectroscopic determination of the DP relies on chemometric models, which are usually sensitive to drifts caused by instrumental and/or sample-associated changes occurring over time. In order to detect the time point when drifts start causing prediction bias, we here explore a universal drift detector based on a faded version of the Page-Hinkley (PH) statistic, which we test in three data streams from an industrial MF resin production process. We employ committee disagreement (CD), computed as the variance of model predictions from an ensemble of partial least squares (PLS) models, as a measure for sample-wise prediction uncertainty and use the PH statistic to detect changes in this quantity. We further explore supervised and unsupervised strategies for (semi-)automatic model adaptation upon detection of a drift. For the former, manual reference measurements are requested whenever statistical thresholds on Hotelling's T 2 and/or Q-Residuals are violated. Models are subsequently re-calibrated using weighted partial least squares in order to increase the influence of newer samples, which increases the flexibility when adapting to new (drifted) states. Unsupervised model adaptation is carried out exploiting the dual antecedent-consequent structure of a recently developed fuzzy systems variant of PLS termed FLEXFIS-PLS. In particular, antecedent parts are updated while maintaining the internal structure of the local linear predictors (i.e. the consequents). We found improved drift detection capability of the CD compared to Hotelling's T 2 and Q-Residuals when used in combination with the proposed PH test. Furthermore, we found that active selection of samples by active learning (AL) used for subsequent model adaptation is advantageous compared to passive (random) selection in case that a drift leads to persistent prediction bias allowing more rapid adaptation at lower reference measurement rates. Fully unsupervised adaptation using FLEXFIS-PLS could improve predictive accuracy significantly for light drifts but was not able to fully compensate for prediction bias in case of significant lack of fit w.r.t. the latent variable space. Copyright © 2018 Elsevier B.V. All rights reserved.

Highly nitrogen-doped carbon capsules: scalable preparation and high-performance applications in fuel cells and lithium ion batteries.

PubMed

Hu, Chuangang; Xiao, Ying; Zhao, Yang; Chen, Nan; Zhang, Zhipan; Cao, Minhua; Qu, Liangti

2013-04-07

Highly nitrogen-doped carbon capsules (hN-CCs) have been successfully prepared by using inexpensive melamine and glyoxal as precursors via solvothermal reaction and carbonization. With a great promise for large scale production, the hN-CCs, having large surface area and high-level nitrogen content (N/C atomic ration of ca. 13%), possess superior crossover resistance, selective activity and catalytic stability towards oxygen reduction reaction for fuel cells in alkaline medium. As a new anode material in lithium-ion battery, hN-CCs also exhibit excellent cycle performance and high rate capacity with a reversible capacity of as high as 1046 mA h g(-1) at a current density of 50 mA g(-1) after 50 cycles. These features make the hN-CCs developed in this study promising as suitable substitutes for the expensive noble metal catalysts in the next generation alkaline fuel cells, and as advanced electrode materials in lithium-ion batteries.

High Pressure Laminates with Antimicrobial Properties

PubMed Central

Magina, Sandra; Santos, Mauro D.; Ferra, João; Cruz, Paulo; Portugal, Inês; Evtuguin, Dmitry

2016-01-01

High-pressure laminates (HPLs) are durable, resistant to environmental effects and good cost-benefit decorative surface composite materials with special properties tailored to meet market demand. In the present work, polyhexamethylene biguanide (PHMB) was incorporated for the first time into melamine-formaldehyde resin (MF) matrix on the outer layer of HPLs to provide them antimicrobial properties. Chemical binding of PHMB to resin matrix was detected on the surface of produced HPLs by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Antimicrobial evaluation tests were carried out on the ensuing HPLs doped with PHMB against gram-positive Listeria innocua and gram-negative Escherichia coli bacteria. The results revealed that laminates prepared with 1.0 wt % PHMB in MF resin were bacteriostatic (i.e., inhibited the growth of microorganisms), whereas those prepared with 2.4 wt % PHMB in MF resin exhibited bactericidal activity (i.e., inactivated the inoculated microorganisms). The results herein reported disclose a promising strategy for the production of HPLs with antimicrobial activity without affecting basic intrinsic quality parameters of composite material. PMID:28787897

High Pressure Laminates with Antimicrobial Properties.

PubMed

Magina, Sandra; Santos, Mauro D; Ferra, João; Cruz, Paulo; Portugal, Inês; Evtuguin, Dmitry

2016-02-06

High-pressure laminates (HPLs) are durable, resistant to environmental effects and good cost-benefit decorative surface composite materials with special properties tailored to meet market demand. In the present work, polyhexamethylene biguanide (PHMB) was incorporated for the first time into melamine-formaldehyde resin (MF) matrix on the outer layer of HPLs to provide them antimicrobial properties. Chemical binding of PHMB to resin matrix was detected on the surface of produced HPLs by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Antimicrobial evaluation tests were carried out on the ensuing HPLs doped with PHMB against gram-positive Listeria innocua and gram-negative Escherichia coli bacteria. The results revealed that laminates prepared with 1.0 wt % PHMB in MF resin were bacteriostatic ( i.e. , inhibited the growth of microorganisms), whereas those prepared with 2.4 wt % PHMB in MF resin exhibited bactericidal activity ( i.e. , inactivated the inoculated microorganisms). The results herein reported disclose a promising strategy for the production of HPLs with antimicrobial activity without affecting basic intrinsic quality parameters of composite material.

Nitrogen-doped porous carbon derived from biomass waste for high-performance supercapacitor.

PubMed

Ma, Guofu; Yang, Qian; Sun, Kanjun; Peng, Hui; Ran, Feitian; Zhao, Xiaolong; Lei, Ziqiang

2015-12-01

High capacitance property and low cost are the pivotal requirements for practical application of supercapacitor. In this paper, a low cost and high capacitance property nitrogen-doped porous carbon with high specific capacitance is prepared. The as-prepared nitrogen-doped porous carbon employing potato waste residue (PWR) as the carbon source, zinc chloride (ZnCl2) as the activating agent and melamine as nitrogen doping agent. The morphology and structure of the carbon materials are studied by scanning electron microscopy (SEM), N2 adsorption/desorption, X-ray diffraction (XRD) and Raman spectra. The surface area of the nitrogen-doped carbon which prepared under 700°C is found to be 1052m(2)/g, and the specific capacitance as high as 255Fg(-1) in 2M KOH electrolyte is obtained utilize the carbon as electrode materials. The electrode materials also show excellent cyclability with 93.7% coulombic efficiency at 5Ag(-1) current density of for 5000cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thermal performance of glass fiber reinforced intumescent fire retardant coating for structural applications

NASA Astrophysics Data System (ADS)

Ahmad, Faiz; Ullah, Sami; Aziz, Hammad; Omar, Nor Sharifah

2015-07-01

The results of influence of glass fiber addition into the basic intumescent coating formulation towards the enhancement of its thermal insulation properties are presented. The intumescent coatings were formulated from expandable graphite, ammonium polyphosphate, melamine, boric acid, bisphenol A epoxy resin BE-188, polyamide amine H-2310 hardener and fiberglass (FG) of length 3.0 mm. Eight intumescent formulations were developed and the samples were tested for their fire performance by burning them at 450°C, 650°C and 850°C in the furnace for two hours. The effects of each fire test at different temperatures; low and high temperature were evaluated. Scanning Electron Microscope, X-Ray Diffraction technique and Thermo Gravimetric Analysis were conducted on the samples to study the morphology, the chemical components of char and the residual weight of the coatings. The formulation, FG08 containing 7.0 wt% glass fiber provided better results with enhanced thermal insulation properties of the coatings.

Engineering Hollow Carbon Architecture for High-Performance K-Ion Battery Anode.

PubMed

Bin, De-Shan; Lin, Xi-Jie; Sun, Yong-Gang; Xu, Yan-Song; Zhang, Ke; Cao, An-Min; Wan, Li-Jun

2018-05-31

K-ion batteries (KIBs) are now drawing increasing research interest as an inexpensive alternative to Li-ion batteries (LIBs). However, due to the large size of K + , stable electrode materials capable of sustaining the repeated K + intercalation/deintercalation cycles are extremely deficient especially if a satisfactory reversible capacity is expected. Herein, we demonstrated that the structural engineering of carbon into a hollow interconnected architecture, a shape similar to the neuron-cell network, promised high conceptual and technological potential for a high-performance KIB anode. Using melamine-formaldehyde resin as the starting material, we identify an interesting glass blowing effect of this polymeric precursor during its carbonization, which features a skeleton-softening process followed by its spontaneous hollowing. When used as a KIB anode, the carbon scaffold with interconnected hollow channels can ensure a resilient structure for a stable potassiation/depotassiation process and deliver an extraordinary capacity (340 mAh g -1 at 0.1 C) together with a superior cycling stability (no obvious fading over 150 cycles at 0.5 C).

A Surface Plasmon Resonance-Based Optical Fiber Probe Fabricated with Electropolymerized Molecular Imprinting Film for Melamine Detection

PubMed Central

Zheng, Yongping; Zhang, Tingwei; Wu, Songjie; Zhang, Jue; Fang, Jing

2018-01-01

Molecularly imprinted polymer (MIP) films prepared by bulk polymerization suffer from numerous deficiencies, including poor mass transfer ability and difficulty in controlling reaction rate and film thickness, which usually result in poor repeatability. However, polymer film synthesized by electropolymerization methods benefit from high reproducibility, simplicity and rapidity of preparation. In the present study, an Au film served as the refractive index-sensitive metal film to couple with the light leaked out from optical fiber core and the electrode for electropolymerizing MIP film simultaneously. The manufactured probe exhibited satisfactory sensitivity and specificity. Furthermore, the surface morphology and functional groups of the synthesized MIP film were characterized by Atomic Force Microscopy (AFM) and Fourier transform infrared microspectroscopy (FTIR) for further insights into the adsorption and desorption processes. Given the low cost, label-free test, simple preparation process and fast response, this method has a potential application to monitor substances in complicated real samples for out-of-lab test in the future. PMID:29522472

Nitrogen-doped 3D reduced graphene oxide/polyaniline composite as active material for supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Liu, Zhisen; Li, Dehao; Li, Zesheng; Liu, Zhenghui; Zhang, Zhiyuan

2017-11-01

A facile strategy for the fabrication of a nitrogen-doped 3D reduced graphene oxide (N-3D-rGO) macroporous structure is proposed in this paper. The proposed strategy used polystyrene microspheres as the templates and melamine as the nitrogen source. Using β-MnO2 as the oxidant, the as-prepared N-3D-rGO was then composited with polyaniline (PANI) nanowires (denoted as N-3D-rGO/PANI-B). The structure, morphology, and electrochemical properties of the composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, charge-discharge test, and electrochemical impedance spectroscopy. Results revealed that the N-3D-rGO/PANI-B composite has a better specific capacity than the composites prepared with 3D-rGO as the support material and peroxydisulfate as the oxidant. These results suggested that N-3D-rGO/PANI-B has potential applications in supercapacitors.

Molten salt-mediated formation of g-C3N4-MoS2 for visible-light-driven photocatalytic hydrogen evolution

NASA Astrophysics Data System (ADS)

Li, Ni; Zhou, Jing; Sheng, Ziqiong; Xiao, Wei

2018-02-01

Construction of two-dimensional/two-dimensional (2D/2D) hybrid with well-defined composition and microstructure is a general protocol to achieve high-performance catalysts. We herein report preparation of g-C3N4-MoS2 hybrid by pyrolysis of affordable melamine and (NH4)2MoS4 in molten LiCl-NaCl-KCl at 550 °C. Molten salts are confirmed as ideal reaction media for formation of homogeneous hybrid. Characterizations suggest a strong interaction between g-C3N4 and MoS2 in the hybrid, which results in an enhanced visible-light-driven photocatalytic hydrogen generation of the hybrid with an optimal g-C3N4/MoS2 ratio. The present study highlights the merits of molten salt methods on preparation of 2D photocatalysts and provides a rational design of 2D/2D hybrid catalysts for advanced environmental and energy applications.

Microencapsulation of essential oil for insect repellent in food packaging system.

PubMed

Chung, Seong Kyun; Seo, Ji Yeon; Lim, Jung Hoon; Park, Hyung Hwan; Yea, Myeong Jai; Park, Hyun Jin

2013-05-01

Microcapsules containing thyme oil were prepared by in situ polymerization, using melamine-formaldehyde prepolymer as a wall material and 3 different emulsifiers (pluronic F-127, tween 80, and sodium lauryl sulfate [SLS]). The general characteristics and release behavior of microcapsules, and their repellent effect against insects were investigated. The morphology of microcapsules using SLS was spherical shape with smooth surface. Microcapsules began to degrade at 150 °C. The particle size ranged from 1 to 10 μm and the loading efficiency of thyme oil was clearly affected by the emulsifier type. The highest loading efficiency appeared in microcapsules using SLS, which have good thermal resistance and smooth surface. The release rate of thyme oil from microcapsules was not only dependent on the storage temperature but also emulsifier type and microcapsules showed the sustained release properties for a long time. Diets, which were mixed with encapsulated thyme oil, expressed high insect repellent efficacy over 90% for 4 wk. © 2013 Institute of Food Technologists®

[Study of amount of evaporation residue in extracts from plastic kitchen utensils into four food-simulating solvents].

PubMed

Ohno, Hiroyuki; Suzuki, Masako; Kawamura, Yoko

2011-01-01

The amount of evaporation residue was investigated as an index of total amount of non-volatile substances that migrated from plastic kitchen utensils into four food-simulating solvents (water, 4% acetic acid, 20% ethanol and heptane). The samples were 71 products made of 12 types of plastics for food contact use. The amount was determined in accordance with the Japanese testing method. The quantitation limit was 5 µg/mL. In the cases of polyethylene, polypropylene, polystyrene, acrylonitrile styrene resin, acrylonitrile butadiene styrene resin, polyvinyl chloride, polyvinylidene chloride, polymethylpentene, polymethylmethacrylate and polyethylene terephthalate samples, the amount was highest for heptane and very low for the other solvents. On the other hand, in the cases of melamine resin and polyamide samples, the amount was highest for 4% acetic acid or 20% ethanol and lowest for heptane. These results enabled the selection of the most suitable solvent, and the rapid and efficient determination of evaporation residue.

Multiscale Interfacial Strategy to Engineer Mixed Metal-Oxide Anodes toward Enhanced Cycling Efficiency.

PubMed

Ma, Yue; Tai, Cheuk-Wai; Li, Shaowen; Edström, Kristina; Wei, Bingqing

2018-06-13

Interconnected macro/mesoporous structures of mixed metal oxide (MMO) are developed on nickel foam as freestanding anodes for Li-ion batteries. The sustainable production is realized via a wet chemical etching process with bio-friendly chemicals. By means of divalent iron doping during an in situ recrystallization process, the as-developed MMO anodes exhibit enhanced levels of cycling efficiency. Furthermore, this atomic-scale modification coherently synergizes with the encapsulation layer across a micrometer scale. During this step, we develop a quasi-gel-state tri-copolymer, i.e., F127-resorcinol-melamine, as the N-doped carbon source to regulate the interfacial chemistry of the MMO electrodes. Electrochemical tests of the modified Fe x Ni 1- x O@NC-NiF anode in both half-cell and full-cell configurations unravel the favorable suppression of the irreversible capacity loss and satisfactory cyclability at the high rates. This study highlights a proof-of-concept modification strategy across multiple scales to govern the interfacial chemical process of the electrodes toward better reversibility.

Effect of MUF/Epoxy Microcapsules on Mechanical Properties and Fractography of Epoxy Materials

NASA Astrophysics Data System (ADS)

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.

Smartphone-based portable wireless optical system for the detection of target analytes.

PubMed

Gautam, Shreedhar; Batule, Bhagwan S; Kim, Hyo Yong; Park, Ki Soo; Park, Hyun Gyu

2017-02-01

Rapid and accurate on-site wireless measurement of hazardous molecules or biomarkers is one of the biggest challenges in nanobiotechnology. A novel smartphone-based Portable and Wireless Optical System (PAWS) for rapid, quantitative, and on-site analysis of target analytes is described. As a proof-of-concept, we employed gold nanoparticles (GNP) and an enzyme, horse radish peroxidase (HRP), to generate colorimetric signals in response to two model target molecules, melamine and hydrogen peroxide, respectively. The colorimetric signal produced by the presence of the target molecules is converted to an electrical signal by the inbuilt electronic circuit of the device. The converted electrical signal is then measured wirelessly via multimeter in the smartphone which processes the data and displays the results, including the concentration of analytes and its significance. This handheld device has great potential as a programmable and miniaturized platform to achieve rapid and on-site detection of various analytes in a point-of-care testing (POCT) manner. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study on adsorption properties of synthetic materials on marine emulsified oil

NASA Astrophysics Data System (ADS)

Zhang, Zhaoyang; Peng, Shitao; Wang, Xiaoli; Zhou, Ran; Luo, Lei

2018-02-01

As an effective measure for marine oil spill recovery, adsorption treatment can be adopted in areas where mechanical recovery is not applicable. This experiment is mainly aimed at studying the adsorption properties of synthetic materials on emulsified oil. The emulsified oil was prepared by simulating the emulsification process of marine oil spill via a wave-current flume, and the adsorption weights of synthetic materials on emulsified oil were obtained by performing a field adsorption experiment. Polypropylene, nano-polypropylene and hydrophobic melamine sponge were tested by adsorbing a variety of emulsified oils according to the Adsorption Property Test Method (Version F-726) defined by ASTM. Their adsorption weights on emulsified oil (with initial thickness of 5 mm and water content of 20.86%) are 5.42 g/g, 23.5 g/g and 82.15g/g, respectively, which, compared with that on gear oil in the initial state, are respective decreases of 46.39%, 19.88% and 11.84%, demonstrating obvious decreases in their adsorption performances.

Interconnected nitrogen and sulfur dual-doped porous carbon as efficient electrocatalyst for triiodide reduction in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Li, Zhao; Yang, Wang; Xu, Xiuwen; Tang, Yushu; Zeng, Ziwei; Yang, Fan; Zhang, Liqiang; Ning, Guoqing; Xu, Chunming; Li, Yongfeng

2016-09-01

Exploiting cost-effective and efficient counter electrodes (CEs) for the reduction of triiodide (I3-) has been a persistent objective for the development of dye-sensitized solar cells (DSSCs). Here, we propose a strategy for the synthesis of nitrogen and sulfur dual-doped porous carbon (N/S-PC) via a thermal annealing approach by using melamine as N source, and basic magnesium sulfate (BMS) whiskers as S source and templates. Benefiting from the high surface area, unique interconnected structural feature and synergistic effects of N/S dual-doping, the N/S-PC shows excellent electrocatalytic activity toward I3- reduction, which has simultaneously been confirmed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization measurements. The DSSC devices with N/S-PC CEs exhibit a PCE up to 7.41%, which is higher than that of DSSC devices with single heteroatom (N or S) doped CEs and even Pt CEs (7.14%).

Surface-modified multifunctional MIP nanoparticles

PubMed Central

Moczko, Ewa; Poma, Alessandro; Guerreiro, Antonio; de Vargas Sansalvador, Isabel Perez; Caygill, Sarah; Canfarotta, Francesco; Whitcombe, Michael J.; Piletsky, Sergey

2015-01-01

The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly-sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinyl ferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors. PMID:23503559

Enhancing anti-microbial properties of wood-plastic composites produced from timber and plastic wastes.

PubMed

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.

Information system equality for food security--implementation of the food safety control system in Taiwan.

PubMed

Chen, Shaun C; Hsu, Guoo-Shyng Wang; Chiu, Chihwei P

2009-01-01

Food security plays a central role in governing agricultural policies in Taiwan. In addition to overuse or the illegal use of pesticide, meat leanness promoters, animal drugs and melamine in the food supply; as well as foodborne illness draws the greatest public concern due to incidents that occur every year in Taiwan. The present report demonstrates the implementation of a food safety control system in Taiwan. In order to control foodborne outbreaks effectively, the central government of the Department of Health of Taiwan launched the food safety control system which includes both the good hygienic practice (GHP) and the HACCP plan, in the last decade. From 1998 to the present, 302 food affiliations that implemented the system have been validated and accredited by a well-established audit system. The implementation of a food safety control system in compliance with international standards is of crucial importance to ensure complete safety and the high quality of foods, not only for domestic markets, but also for international trade.

Graphite Carbon-Supported Mo2C Nanocomposites by a Single-Step Solid State Reaction for Electrochemical Oxygen Reduction.

PubMed

Huang, K; Bi, K; Liang, C; Lin, S; Wang, W J; Yang, T Z; Liu, J; Zhang, R; Fan, D Y; Wang, Y G; Lei, M

2015-01-01

Novel graphite-molybdenum carbide nanocomposites (G-Mo2C) are synthesized by a typical solid state reaction with melamine and MoO3 as precursors under inert atmosphere. The characterization results indicate that G-Mo2C composites are composed of high crystallization and purity of Mo2C and few layers of graphite carbon. Mo2C nanoparticles with sizes ranging from 5 to 50 nm are uniformly supported by surrounding graphite layers. It is believed that Mo atom resulting from the reduction of MoO3 is beneficial to the immobilization of graphite carbon. Moreover, the electrocatalytic performances of G-Mo2C for ORR in alkaline medium are investigated by cyclic voltammetry (CV), rotating disk electrode (RDE) and chronoamperometry test with 3M methanol. The results show that G-Mo2C has a considerable catalytic activity and superior methanol tolerance performance for the oxygen reduction reaction (ORR) benefiting from the chemical interaction between the carbide nanoparticles and graphite carbon.

A mechanistic approach on the self-organization of the two-component thermoreversible hydrogel of riboflavin and melamine.

PubMed

Saha, Abhijit; Manna, Swarup; Nandi, Arun K

2007-12-18

The riboflavin (R) and melamine (M) supramolecular complex in the mole ratio of 3:1 (RM31) produces a thermoreversible gel in aqueous medium. The gelation mechanism has been elucidated from morphological investigations using optical, electron, and atomic force microscopy together with time-dependent circular dichroism (CD) and photoluminescence (PL) spectroscopy. Optical microscopy indicates spherulitic morphology at lower gelation temperature (

Scanning transmission electron microscopy analysis of Ge(O)/(graphitic carbon nitride) nanocomposite powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawasaki, Masahiro; Sompetch, Kanganit; Sarakonsri, Thapanee, E-mail: tsarakonsri@gmail.com

2015-12-15

Analytical electron microscopy has revealed the structure of particles that were synthesized by chemical reaction of GeO{sub 2} with NaBH{sub 4} in the basic solution including graphitic carbon nitride (g-C{sub 3}N{sub 4}) powders. The g-C{sub 3}N{sub 4} was arranged by recrystallization of melamine at 600 °C under N{sub 2} gas atmosphere. The samples were dried at 60 °C or 180 °C for 4 h. The g-C{sub 3}N{sub 4} was observed as lamellae of several ten nm or less in size and had an amorphous-like structure with a distorted lattice in an area as small as a few hundred pm inmore » size. The reaction product was Ge(O) particles as fine as several nm in size and composed of Ge and O atoms. Most of the particles must be of GeO{sub 2−x} with the amorphous-like structure that has also a distorted lattice in an area of a few hundred pm in size. In the sample dried at 60 °C, the particles were found to be dispersed in a wide area on the g-C{sub 3}N{sub 4} lamella. It is hard to recognize those particles in TEM images. The particles in the sample dried at 180 °C became larger and were easily observed as isolated lumps. Hence, these powders can be regarded as GeO{sub 2}/g-C{sub 3}N{sub 4} or Ge/GeO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites, and expected to be applicable to anode materials for high energy Li-ion batteries due to Ge catalysis effect, accordingly. - Graphical abstract: STEM analysis of Ge(O)/(graphitic carbon nitride) nanocomposite powder. - Highlights: • Graphitic (g)-C{sub 3}N{sub 4} powder was prepared at 600 °C by recrystallization of melamine. • Ge(O) was prepared by chemical reaction in a solution including the g-C{sub 3}N{sub 4} powders. • The products can be regarded as GeO{sub 2}/g-C{sub 3}N{sub 4} or Ge/GeO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites. • GeO{sub 2} was amorphous several-nm particles and g-C{sub 3}N{sub 4} was amorphous lamella of several 10 nm in size. • We expect them to be applicable for high energy Li-ion battery anode materials.« less

Tailored Design of Bicontinuous Gyroid Mesoporous Carbon and Nitrogen-Doped Carbon from Poly(ethylene oxide-b-caprolactone) Diblock Copolymers.

PubMed

Chu, Wei-Cheng; Bastakoti, Bishnu Prasad; Kaneti, Yusuf Valentino; Li, Jheng-Guang; Alamri, Hatem R; Alothman, Zeid A; Yamauchi, Yusuke; Kuo, Shiao-Wei

2017-10-04

Highly ordered mesoporous resol-type phenolic resin and the corresponding mesoporous carbon materials were synthesized by using poly(ethylene oxide-b-caprolactone) (PEO-b-PCL) diblock copolymer as a soft template. The self-assembled mesoporous phenolic resin was found to form only in a specific resol concentration range of 40-70 wt % due to an intriguing balance of hydrogen-bonding interactions in the resol/PEO-b-PCL mixtures. Furthermore, morphological transitions of the mesostructures from disordered to gyroid to cylindrical and finally to disordered micelle structure were observed with increasing resol concentration. By calcination under nitrogen atmosphere at 800 °C, the bicontinuous mesostructured gyroid phenolic resin could be converted to mesoporous carbon with large pore size without collapse of the original mesostructure. Furthermore, post-treatment of the mesoporous gyroid phenolic resin with melamine gave rise to N-doped mesoporous carbon with unique electronic properties for realizing high CO 2 adsorption capacity (6.72 mmol g -1 at 0 °C). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Iron encapsulated in 3D N-doped carbon nanotube/porous carbon hybrid from waste biomass for enhanced oxidative activity.

PubMed

Yao, Yunjin; Zhang, Jie; Wu, Guodong; Wang, Shaobin; Hu, Yi; Su, Cong; Xu, Tongwen

2017-03-01

Novel iron encapsulated in nitrogen-doped carbon nanotubes (CNTs) supported on porous carbon (Fe@N-C) 3D structured materials for degrading organic pollutants were fabricated from a renewable, low-cost biomass, melamine, and iron salt as the precursors. SEM and TEM micrographs show that iron encapsulated bamboo shaped CNTs are vertically standing on carbon sheets, and thus, a 3D hybrid was formed. The catalytic activities of the prepared samples were thoroughly evaluated by activation of peroxymonosulfate for catalytic oxidation of Orange II solutions. The influences of some reaction conditions (pH, temperature, and concentrations of reactants, peroxymonosulfate, and dye) were extensively evaluated. It was revealed that the adsorption could enrich the pollutant which was then rapidly degraded by the catalytically generated radicals, accelerating the continuous adsorption of residual pollutant. Remarkable carbon structure, introduction of CNTs, and N/Fe doping result in promoted adsorption capability and catalytic performances. Due to the simple synthetic process and cheap carbon precursor, Fe@N-C 3D hybrid can be easily scaled up and promote the development of Fenton-like catalysts.

Microwave-assisted rapid preparation of monodisperse superhydrophilic resin microspheres as adsorbent for triazines in fruit juices.

PubMed

Zhou, Tianyu; Ding, Jie; Wang, Qiang; Xu, Yuan; Wang, Bo; Zhao, Li; Ding, Hong; Chen, Yanhua; Ding, Lan

2018-03-01

Monodisperse superhydrophilic melamine formaldehyde resorcinol resin (MFR) microspheres were prepared in 90min at 85°C via a microwave-assisted method with a yield of 60.6%. The obtained MFR microspheres exhibited narrow size distribution with the average particle size of about 2.5µm. The MFR microspheres were used as absorbents to detect triazines in juices followed by high performance liquid chromatography tandem mass spectrometry. Various factors affecting the extraction efficiency were investigated. Under the optimized conditions, the built method exhibited excellent linearity in the range of 1-250μgL -1 (R 2 ≥ 0.9994) and lower detection limits (0.3-0.65μgL -1 ). The relative standard deviations of intra- and inter-day analyses ranged from 3% to 7% and from 2% to 7%, respectively. The method was applied to determine six triazines in three juice samples. At the spiked level of 3μgL -1 , the recoveries were in the range of 90-99% with the relative standard deviations ≤ 8%. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile synthesis of porous graphene-like carbon nitride nanosheets with high surface area and enhanced photocatalytic activity via one-step catalyst-free solution self-polymerization

NASA Astrophysics Data System (ADS)

Wu, Shikai; Wen, Shengwu; Xu, Xinmei; Huang, Guozhi; Cui, Yifan; Li, Jinyu; Qu, Ailan

2018-04-01

Porous graphite carbon nitride nanosheets (g-C3N4) are achieved via one-step catalyst-free solution self-polymerization from a single melamine precursor. The resultant porous g-C3N4 nanosheets with the best photodegradation capacity provided the surface area of 669.15 m2/g, which is superior to the surface area of any other porous g-C3N4 reported. Results showed enhanced adsorption and degradation capacity of methyl orange (MO) under UV-visible light irradiation (λ > 350 nm) compared to bulk g-C3N4. The MO oxidation of the porous g-C3N4 nanosheets is driven mostly by the participation of holes, and secondly by rad O2- and rad OH radicals. This approach shed lights on porous g-C3N4 production simply by self-polycondensation of single functional monomer. It also provided a low-cost and eco-friendly method to facilely mass-produce g-C3N4 nanosheets with high surface area for many potential applications.

pH-Triggered Molecular Alignment for Reproducible SERS Detection via an AuNP/Nanocellulose Platform

PubMed Central

Wei, Haoran; Vikesland, Peter J.

2015-01-01

The low affinity of neutral and hydrophobic molecules towards noble metal surfaces hinders their detection by surface-enhanced Raman spectroscopy (SERS). Herein, we present a method to enhance gold nanoparticle (AuNP) surface affinity by lowering the suspension pH below the analyte pKa. We developed an AuNP/bacterial cellulose (BC) nanocomposite platform and applied it to two common pollutants, carbamazepine (CBZ) and atrazine (ATZ) with pKa values of 2.3 and 1.7, respectively. Simple mixing of the analytes with AuNP/BC at pH < pKa resulted in consistent electrostatic alignment of the CBZ and ATZ molecules across the nanocomposite and highly reproducible SERS spectra. Limits of detection of 3 nM and 11 nM for CBZ and ATZ, respectively, were attained. Tests with additional analytes (melamine, 2,4-dichloroaniline, 4-chloroaniline, 3-bromoaniline, and 3-nitroaniline) further illustrate that the AuNP/BC platform provides reproducible analyte detection and quantification while avoiding the uncontrolled aggregation and flocculation of AuNPs that often hinder low pH detection. PMID:26658696

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Limiao, E-mail: chenlimiao@csu.edu.cn; Jing, Qifeng; Chen, Jun

Silver nanostructures with dendritic, flower-like and irregular morphologies were controllably deposited on a silicon substrate in an aqueous hydrogen fluoride solution at room temperature. The morphology of the Ag nanostructures changed from dendritic to urchin-like, flowerlike and pinecone-like with increasing the concentration of polyvinyl pyrrolidone (MW = 55,000) from 2 to 10 mM. The Ag nanostructures were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction. Through a series of time-dependent morphological evolution studies, the growth processes of Ag nanostructures have been systematically investigated and the corresponding growth mechanisms have been discussed.more » In addition, the morphology-dependent surface-enhanced Raman scattering of as-synthesized Ag nanostructures were investigated. The results indicated that flower-like Ag nanostructure had the highest activity than the other Ag nanostructures for Rhodamine 6G probe molecules. Highlights: • A simple method was developed to prepare dendritic and flower-like Ag nanostructures. • The flower-like Ag nanoparticles exhibit highest SERS activity. • The SERS substrate based on flower-like Ag particles can be used to detect melamine.« less

Periodic silver nanocluster arrays over large-area silica nanosphere template as highly sensitive SERS substrate

NASA Astrophysics Data System (ADS)

Hou, Xu; Wang, Qi; Mao, Guoming; Liu, Hao; Yu, Rongdi; Ren, Xiaomin

2018-04-01

Periodic Ag nanocluster arrays for surface enhanced Raman spectroscopy (SERS) were fabricated through magnetron sputtering Ag over a large-area monolayer template which is based on silica (SiO2) nanospheres. High-density nanogaps between the adjacent Ag nanoclusters acted as "hot-spots", making a dominant contribution to the high-performance SERS detection. Moreover, the nanospheres and Ag nanoclusters effectively increased the surface roughness and also enlarged the surface area of as-obtained SERS substrate, which resulted in a further enhancement in Raman signals. As-prepared SERS substrates showed very high sensitivity with the enhancement factor (EF) value of 4.1 × 1012 for Rhodamine 6G (R6G), allowing the corresponding detection limit as low as 10-16 M. Additionally, SERS signal of melamine was still strong even though its concentration was lowered to 10-7 M. Our results show that preparing highly sensitive SERS substrate with periodic Ag nanoclusters over SiO2 nanosphere template is a convenient and promising pathway for chemical and biologic sensing.

Raman Spectroscopy of Cocrystals

NASA Astrophysics Data System (ADS)

Rooney, Frank; Reardon, Paul; Ochoa, Romulo; Abourahma, Heba; Marti, Marcus; Dimeo, Rachel

2010-02-01

Cocrystals are a class of compounds that consist of two or more molecules that are held together by hydrogen bonding. Pharmaceutical cocrystals are those that contain an active pharmaceutical ingredient (API) as one of the components. Pharmaceutical cocrystals are of particular interest and have gained a lot of attention in recent years because they offer the ability to modify the physical properties of the API, like solubility and bioavailability, without altering the chemical structure of the API. The APIs that we targeted for our studies are theophylline (Tp) and indomethacin (Ind). These compounds have been mixed with complementary coformers (cocrystal former) that include acetamide (AcONH2), melamine (MLM), nicotinic acid (Nic-COOH), 4-cyanopyridine (4-CNPy) and 4-aminopyridine (4-NH2Py). Raman spectroscopy has been used to characterize these cocrystals. Spectra of the cocrystals were compared to those of the coformers to analyze for peak shifts, specifically those corresponding to hydrogen bonding. A 0.5 m CCD Spex spectrometer was used, in a micro-Raman setup, for spectral analysis. An Argon ion Coherent laser at 514.5 nm was used as the excitation source. )

Fire propagation performance of intumescent fire protective coatings using eggshells as a novel biofiller.

PubMed

Yew, M C; Ramli Sulong, N H; Yew, M K; Amalina, M A; Johan, M R

2014-01-01

This paper aims to synthesize and characterize an effective intumescent fire protective coating that incorporates eggshell powder as a novel biofiller. The performances of thermal stability, char formation, fire propagation, water resistance, and adhesion strength of coatings have been evaluated. A few intumescent flame-retardant coatings based on these three ecofriendly fire retardant additives ammonium polyphosphate phase II, pentaerythritol and melamine mixed together with flame-retardant fillers, and acrylic binder have been prepared and designed for steel. The fire performance of the coatings has conducted employing BS 476: Part 6-Fire propagation test. The foam structures of the intumescent coatings have been observed using field emission scanning electron microscopy. On exposure, the coated specimens' B, C, and D had been certified to be Class 0 due to the fact that their fire propagation indexes were less than 12. Incorporation of ecofriendly eggshell, biofiller into formulation D led to excellent performance in fire stopping (index value, (I) = 4.3) and antioxidation of intumescent coating. The coating is also found to be quite effective in water repellency, uniform foam structure, and adhesion strength.

pH-Triggered Molecular Alignment for Reproducible SERS Detection via an AuNP/Nanocellulose Platform

NASA Astrophysics Data System (ADS)

Wei, Haoran; Vikesland, Peter J.

2015-12-01

The low affinity of neutral and hydrophobic molecules towards noble metal surfaces hinders their detection by surface-enhanced Raman spectroscopy (SERS). Herein, we present a method to enhance gold nanoparticle (AuNP) surface affinity by lowering the suspension pH below the analyte pKa. We developed an AuNP/bacterial cellulose (BC) nanocomposite platform and applied it to two common pollutants, carbamazepine (CBZ) and atrazine (ATZ) with pKa values of 2.3 and 1.7, respectively. Simple mixing of the analytes with AuNP/BC at pH < pKa resulted in consistent electrostatic alignment of the CBZ and ATZ molecules across the nanocomposite and highly reproducible SERS spectra. Limits of detection of 3 nM and 11 nM for CBZ and ATZ, respectively, were attained. Tests with additional analytes (melamine, 2,4-dichloroaniline, 4-chloroaniline, 3-bromoaniline, and 3-nitroaniline) further illustrate that the AuNP/BC platform provides reproducible analyte detection and quantification while avoiding the uncontrolled aggregation and flocculation of AuNPs that often hinder low pH detection.

A Plasmonic Mass Spectrometry Approach for Detection of Small Nutrients and Toxins

NASA Astrophysics Data System (ADS)

Wu, Shu; Qian, Linxi; Huang, Lin; Sun, Xuming; Su, Haiyang; Gurav, Deepanjali D.; Jiang, Mawei; Cai, Wei; Qian, Kun

2018-07-01

Nutriology relies on advanced analytical tools to study the molecular compositions of food and provide key information on sample quality/safety. Small nutrients detection is challenging due to the high diversity and broad dynamic range of molecules in food samples, and a further issue is to track low abundance toxins. Herein, we developed a novel plasmonic matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) approach to detect small nutrients and toxins in complex biological emulsion samples. Silver nanoshells (SiO2@Ag) with optimized structures were used as matrices and achieved direct analysis of 6 nL of human breast milk without any enrichment or separation. We performed identification and quantitation of small nutrients and toxins with limit-of-detection down to 0.4 pmol (for melamine) and reaction time shortened to minutes, which is superior to the conventional biochemical method currently in use. The developed approach contributes to the near-future application of MALDI MS in a broad field and personalized design of plasmonic materials for real-case bio-analysis.[Figure not available: see fulltext.

High-throughput Raman chemical imaging for evaluating food safety and quality

NASA Astrophysics Data System (ADS)

Qin, Jianwei; Chao, Kuanglin; Kim, Moon S.

2014-05-01

A line-scan hyperspectral system was developed to enable Raman chemical imaging for large sample areas. A custom-designed 785 nm line-laser based on a scanning mirror serves as an excitation source. A 45° dichroic beamsplitter reflects the laser light to form a 24 cm x 1 mm excitation line normally incident on the sample surface. Raman signals along the laser line are collected by a detection module consisting of a dispersive imaging spectrograph and a CCD camera. A hypercube is accumulated line by line as a motorized table moves the samples transversely through the laser line. The system covers a Raman shift range of -648.7-2889.0 cm-1 and a 23 cm wide area. An example application, for authenticating milk powder, was presented to demonstrate the system performance. In four minutes, the system acquired a 512x110x1024 hypercube (56,320 spectra) from four 47-mm-diameter Petri dishes containing four powder samples. Chemical images were created for detecting two adulterants (melamine and dicyandiamide) that had been mixed into the milk powder.

Photoresponse of supramolecular self-assembled networks on graphene-diamond interfaces.

PubMed

Wieghold, Sarah; Li, Juan; Simon, Patrick; Krause, Maximilian; Avlasevich, Yuri; Li, Chen; Garrido, Jose A; Heiz, Ueli; Samorì, Paolo; Müllen, Klaus; Esch, Friedrich; Barth, Johannes V; Palma, Carlos-Andres

2016-02-25

Nature employs self-assembly to fabricate the most complex molecularly precise machinery known to man. Heteromolecular, two-dimensional self-assembled networks provide a route to spatially organize different building blocks relative to each other, enabling synthetic molecularly precise fabrication. Here we demonstrate optoelectronic function in a near-to-monolayer molecular architecture approaching atomically defined spatial disposition of all components. The active layer consists of a self-assembled terrylene-based dye, forming a bicomponent supramolecular network with melamine. The assembly at the graphene-diamond interface shows an absorption maximum at 740 nm whereby the photoresponse can be measured with a gallium counter electrode. We find photocurrents of 0.5 nA and open-circuit voltages of 270 mV employing 19 mW cm(-2) irradiation intensities at 710 nm. With an ex situ calculated contact area of 9.9 × 10(2) μm(2), an incident photon to current efficiency of 0.6% at 710 nm is estimated, opening up intriguing possibilities in bottom-up optoelectronic device fabrication with molecular resolution.

Effect of nonionic compound emulsifiers Tween80 and Span80 on the properties of microencapsulated phase change materials.

PubMed

Zhan, Shiping; Zhou, Zhiyi; Wang, Weijing; Zhao, Qicheng; Hou, Weimin

2014-01-01

In this article, the nonionic compound emulsifiers Tween80 and Span80 were used to prepare microcapsules containing phase change materials (microPCMs) with melamine-formaldehyde (MF) shells by in situ polymerization method. The effects of compound emulsifiers Tween80 and Span80 on the structure, morphologies and properties of microPCMs containing paraffin were studied. SEM morphological investigation suggests that a complex of Tween80 and Span80 as emulsifiers are optimal for the fabrication of microPCMs in this study compared to Tween60 or OP-10. The diameter distributions of microPCMs synthesized with different amounts of compound emulsifiers are uniform, whereas compound emulsifiers' amount affect the mean diameter of microPCMs decreasing from 5.34 to 3.05 µm. These microPCMs with the core/shell weight ratio 3/1 have smoother surface and a higher core content of 68.7% than other core/shell ratio. Anti-osmosis measurements indicate that microPCMs have good compactness and stable performance compared to those synthesized by one type of emulsifier.

Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam

NASA Technical Reports Server (NTRS)

Hughes, William O.; McNelis, Anne M.; Chris Nottoli; Eric Wolfram

2015-01-01

The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the diffraction edge effect phenomenon. An investigative test program to measure the absorption properties of highly absorbent melamine foam has been performed at the Riverbank Acoustical Laboratories. This paper will present and discuss the test results relating to the effect of the test materials' surface area, thickness and edge sealing conditions. A follow-on paper is envisioned that will present and discuss the results relating to the spacing between multiple piece specimens, and the mounting condition of the test specimen.

Wideband characterization of the complex wave number and characteristic impedance of sound absorbers.

PubMed

Salissou, Yacoubou; Panneton, Raymond

2010-11-01

Several methods for measuring the complex wave number and the characteristic impedance of sound absorbers have been proposed in the literature. These methods can be classified into single frequency and wideband methods. In this paper, the main existing methods are revisited and discussed. An alternative method which is not well known or discussed in the literature while exhibiting great potential is also discussed. This method is essentially an improvement of the wideband method described by Iwase et al., rewritten so that the setup is more ISO 10534-2 standard-compliant. Glass wool, melamine foam and acoustical/thermal insulator wool are used to compare the main existing wideband non-iterative methods with this alternative method. It is found that, in the middle and high frequency ranges the alternative method yields results that are comparable in accuracy to the classical two-cavity method and the four-microphone transfer-matrix method. However, in the low frequency range, the alternative method appears to be more accurate than the other methods, especially when measuring the complex wave number.

[Determination of total protein content in soya-bean milk via visual moving reaction boundary titration].

PubMed

Guo, Chengye; Wang, Houyu; Zhang, Lei; Fan, Liuyin; Cao, Chengxi

2013-11-01

A visual, rapid and accurate moving reaction boundary titration (MRBT) method was used for the determination of the total protein in soya-bean milk. During the process, moving reaction boundary (MRB) was formed by hydroxyl ions in the catholyte and soya-bean milk proteins immobilized in polyacrylamide gel (PAG), and an acid-base indicator was used to denote the boundary motion. The velocity of MRB has a relationship with protein concentration, which was used to obtain a standard curve. By paired t-test, there was no significant difference of the protein content between MRBT and Kjeldahl method at 95% confidence interval. The procedure of MRBT method required about 10 min, and it had linearity in the range of 2.0-14.0 g/L, low limit of detection (0.05 g/L), good precision (RSD of intra-day < 1.90% and inter-day < 4.39%), and high recoveries (97.41%-99.91%). In addition, non-protein nitrogen (NPN) such as melamine added into the soya-bean milk had weak influence on MRBT results.

Metabolomics approach of infant formula for the evaluation of contamination and degradation using hydrophilic interaction liquid chromatography coupled with mass spectrometry.

PubMed

Inoue, Koichi; Tanada, Chihiro; Sakamoto, Tasuku; Tsutsui, Haruhito; Akiba, Takashi; Min, Jun Zhe; Todoroki, Kenichiro; Yamano, Yutaka; Toyo'oka, Toshimasa

2015-08-15

In this study including the field of metabolomics approach for food, the evaluation of untargeted compounds using HILIC-ESI/TOF/MS and multivariate statistical analysis method is proposed for the assessment of classification, contamination and degradation of infant formula. HILIC mode is used to monitor more detected numbers in infant formulas in the ESI-positive scan mode than the reversed phase. The repeatability of the non-targeted contents from 4 kinds of infant formulas based on PCA was less than the relative standard deviation of 15% in all groups. The PCA pattern showed that significant differences in the classification of types and origins, the contamination of melamine and the degradations for one week were evaluated using HILIC-ESI/TOF/MS. In the S-plot from the degradation test, we could identify two markers by comparison to standards as nicotinic acid and nicotinamide. With this strategy, the differences from the untargeted compounds could be utilized for quality and safety assessment of infant formula. Copyright © 2015 Elsevier Ltd. All rights reserved.

Novel Polymer Aerogel toward High Dimensional Stability, Mechanical Property, and Fire Safety.

PubMed

Shang, Ke; Yang, Jun-Chi; Cao, Zhi-Jie; Liao, Wang; Wang, Yu-Zhong; Schiraldi, David A

2017-07-12

Inorganc silica-based aerogels, the earliest and widely used aerogels, have poorer mechanical properties than their organic substitutes, which are flammable. In this study, a novel polymeric aerogel with high strength, inherent flame retardancy, and cost-effectiveness, which is based on poly(vinyl alcohol) (PVA) cross-linked with melamine-formaldehyde (MF), was prepared under aqueous condition with an ecofriendly freeze-drying and postcuring process. Combined with the additional rigid MF network and benifited from the resulting unique infrastructure of inter-cross-linked flexible PVA segments and rigid MF segments, PVA-based aerogels exibited a significantly decreased degradation rate and sharply decreased peak heat release rate (PHRR) in cone calorimeter tests (by as much as 83%) compared with neat PVA. The polymer aerogels have a limiting oxygen index (LOI) as high as 36.5% and V-0 rating in UL-94 test. Furthermore, the aerogel samples exposured to harsh temperatures maintain their dimensions (<10% change), original mechanical strength and fire safety. Therefore, this work provides a novel stragegy for preparing pure organic polymeric aerogel materials with high mechanical strength, dimensional stability, and fire safety.

On-chip ultra-thin layer chromatography and surface enhanced Raman spectroscopy.

PubMed

Chen, Jing; Abell, Justin; Huang, Yao-wen; Zhao, Yiping

2012-09-07

We demonstrate that silver nanorod (AgNR) array substrates can be used for on-chip separation and detection of chemical mixtures by combining ultra-thin layer chromatography (UTLC) and surface enhanced Raman spectroscopy (SERS). The UTLC-SERS plate consists of an AgNR array fabricated by oblique angle deposition. The capability of the AgNR substrates to separate the different compounds in a mixture was explored using a mixture of four dyes and a mixture of melamine and Rhodamine 6G at varied concentrations with different mobile phase solvents. After UTLC separation, spatially-resolved SERS spectra were collected along the mobile phase development direction and the intensities of specific SERS peaks from each component were used to generate chromatograms. The AgNR substrates demonstrate the potential for separating the test dyes with plate heights as low as 9.6 μm. The limits of detection are between 10(-5)-10(-6) M. Furthermore, we show that the coupling of UTLC with SERS improves the SERS detection specificity, as small amounts of target analytes can be separated from the interfering background components.

Fabrication of sophisticated two-dimensional organic nanoarchitectures thought hydrogen bond mediated molecular self assembly

NASA Astrophysics Data System (ADS)

Silly, Fabien

2012-02-01

Complex supramolecular two-dimensional (2D) networks are attracting considerable interest as highly ordered functional materials for applications in nanotechnology. The challenge consists in tailoring the ordering of one or more molecular species into specific architectures over an extended length scale with molecular precision. Highly organized supramolecular arrays can be obtained through self-assembly of complementary molecules which can interlock via intermolecular interactions. Molecules forming hydrogen bonds (H-bonds) are especially interesting building blocks for creating sophisticated organic architectures due to high selectivity and directionality of these bindings. We used scanning tunnelling microscopy to investigate at the atomic scale the formation of H-bonded 2D organic nanoarchitectures on surfaces. We mixed perylene derivatives having rectangular shape with melamine and DNA base having triangular and non symmetric shape respectively. We observe that molecule substituents play a key role in formation of the multicomponent H-bonded architectures. We show that the 2D self-assembly of these molecules can be tailored by adjusting the temperature and molecular ratio. We used these stimuli to successfully create numerous close-packed and porous 2D multicomponent structures.

Direct writing electrodes using a ball pen for paper-based point-of-care testing.

PubMed

Li, Zedong; Li, Fei; Hu, Jie; Wee, Wei Hong; Han, Yu Long; Pingguan-Murphy, Belinda; Lu, Tian Jian; Xu, Feng

2015-08-21

The integration of paper with an electrochemical device has attracted growing attention for point-of-care testing, where it is of great importance to fabricate electrodes on paper in a low-cost, easy and versatile way. In this work, we report a simple strategy for directly writing electrodes on paper using a pressure-assisted ball pen to form a paper-based electrochemical device (PED). This method is demonstrated to be capable of fabricating electrodes on paper with good electrical conductivity and electrochemical performance, holding great potential to be employed in point-of-care applications, such as in human health diagnostics and food safety detection. As examples, the PEDs fabricated using the developed method are applied for detection of glucose in artificial urine and melamine in sample solutions. Furthermore, our developed strategy is also extended to fabricate PEDs with multi-electrode arrays and write electrodes on non-planar surfaces (e.g., paper cup, human skin), indicating the potential application of our method in other fields, such as fabricating biosensors, paper electronics etc.

Fire Propagation Performance of Intumescent Fire Protective Coatings Using Eggshells as a Novel Biofiller

PubMed Central

Yew, M. C.; Ramli Sulong, N. H.; Yew, M. K.; Amalina, M. A.; Johan, M. R.

2014-01-01

This paper aims to synthesize and characterize an effective intumescent fire protective coating that incorporates eggshell powder as a novel biofiller. The performances of thermal stability, char formation, fire propagation, water resistance, and adhesion strength of coatings have been evaluated. A few intumescent flame-retardant coatings based on these three ecofriendly fire retardant additives ammonium polyphosphate phase II, pentaerythritol and melamine mixed together with flame-retardant fillers, and acrylic binder have been prepared and designed for steel. The fire performance of the coatings has conducted employing BS 476: Part 6-Fire propagation test. The foam structures of the intumescent coatings have been observed using field emission scanning electron microscopy. On exposure, the coated specimens' B, C, and D had been certified to be Class 0 due to the fact that their fire propagation indexes were less than 12. Incorporation of ecofriendly eggshell, biofiller into formulation D led to excellent performance in fire stopping (index value, (I) = 4.3) and antioxidation of intumescent coating. The coating is also found to be quite effective in water repellency, uniform foam structure, and adhesion strength. PMID:25136687

A rapid and accurate method for determining protein content in dairy products based on asynchronous-injection alternating merging zone flow-injection spectrophotometry.

PubMed

Liang, Qin-Qin; Li, Yong-Sheng

2013-12-01

An accurate and rapid method and a system to determine protein content using asynchronous-injection alternating merging zone flow-injection spectrophotometry based on reaction between coomassie brilliant blue G250 (CBBG) and protein was established. Main merit of our approach is that it can avoid interferences of other nitric-compounds in samples, such as melamine and urea. Optimized conditions are as follows: Concentrations of CBBG, polyvinyl alcohol (PVA), NaCl and HCl are 150 mg/l, 30 mg/l, 0.1 mol/l and 1.0% (v/v), respectively; volumes of the sample and reagent are 150 μl and 30 μl, respectively; length of a reaction coil is 200 cm; total flow rate is 2.65 ml/min. The linear range of the method is 0.5-15 mg/l (BSA), its detection limit is 0.05 mg/l, relative standard deviation is less than 1.87% (n=11), and analytical speed is 60 samples per hour. Copyright © 2013 Elsevier Ltd. All rights reserved.

Colloidal micro- and nano-particles as templates for polyelectrolyte multilayer capsules.

PubMed

Parakhonskiy, Bogdan V; Yashchenok, Alexey M; Konrad, Manfred; Skirtach, Andre G

2014-05-01

Colloidal particles play an important role in various areas of material and pharmaceutical sciences, biotechnology, and biomedicine. In this overview we describe micro- and nano-particles used for the preparation of polyelectrolyte multilayer capsules and as drug delivery vehicles. An essential feature of polyelectrolyte multilayer capsule preparations is the ability to adsorb polymeric layers onto colloidal particles or templates followed by dissolution of these templates. The choice of the template is determined by various physico-chemical conditions: solvent needed for dissolution, porosity, aggregation tendency, as well as release of materials from capsules. Historically, the first templates were based on melamine formaldehyde, later evolving towards more elaborate materials such as silica and calcium carbonate. Their advantages and disadvantages are discussed here in comparison to non-particulate templates such as red blood cells. Further steps in this area include development of anisotropic particles, which themselves can serve as delivery carriers. We provide insights into application of particles as drug delivery carriers in comparison to microcapsules templated on them. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zia-ul-Mustafa, M., E-mail: engr.ziamustafa@gmail.com; Ahmad, Faiz; Megat-Yusoff, Puteri S. M.

In this study, intumescent fire retardant coatings (IFRC) were developed to investigate the synergistic effects of reinforced mica and wollastonite fillers based IFRC towards heat shielding, char expansion, char composition and char morphology. Ammonium poly-phosphate (APP) was used as acid source, expandable graphite (EG) as carbon source, melamine as blowing agent, boric acid as additive and Hardener H-2310 polyamide amine in bisphenol A epoxy resin BE-188(BPA) was used as curing agent. Bunsen burner fire test was used for thermal performance according to UL-94 for 1 h. Field Emission Scanning Electron Microscopy (FESEM) was used to observe char microstructure. X-Ray Diffraction (XRD)more » and Fourier transform infrared spectroscopy (FTIR) were used to analyse char composition. The results showed that addition of clay filler in IFRC enhanced the fire protection performance of intumescent coating. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results showed the presence of boron phosphate, silicon phosphate oxide, aluminium borate in the char that improved the thermal performance of intumescent fire retardant coating (IFRC). Resultantly, the presence of these developed compounds enhanced the Integrity of structural steel upto 500°C.« less

Chromatographic separation and detection of contaminants from whole milk powder using a chitosan-modified silver nanoparticles surface-enhanced Raman scattering device.

PubMed

Li, Dan; Lv, Di Y; Zhu, Qing X; Li, Hao; Chen, Hui; Wu, Mian M; Chai, Yi F; Lu, Feng

2017-06-01

Methods for the on-site analysis of food contaminants are in high demand. Although portable Raman spectroscopy is commonly used to test food on-site, it can be challenge to achieve this goal with rapid detection and inexpensive substrate. In this study, we detected trace food contaminants in samples of whole milk powder using the methods that combined chromatography with surface-enhanced Raman scattering detection (SERS). We developed a simple and efficient technique to fabricate the paper with chitosan-modified silver nanoparticles as a SERS-active substrate. The soaking time of paper and the concentration of chitosan solution were optimized for chromatographic separation and SERS detection. We then studied the separation properties for real applications including complex sample matrices, and detected melamine at 1mg/L, dicyandiamide at 100mg/L and sodium sulfocyanate at 10mg/L in whole milk powder. As such, our methods have great potential for field-based detection of milk contaminants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photoresponse of supramolecular self-assembled networks on graphene–diamond interfaces

PubMed Central

Wieghold, Sarah; Li, Juan; Simon, Patrick; Krause, Maximilian; Avlasevich, Yuri; Li, Chen; Garrido, Jose A.; Heiz, Ueli; Samorì, Paolo; Müllen, Klaus; Esch, Friedrich; Barth, Johannes V.; Palma, Carlos-Andres

2016-01-01

Nature employs self-assembly to fabricate the most complex molecularly precise machinery known to man. Heteromolecular, two-dimensional self-assembled networks provide a route to spatially organize different building blocks relative to each other, enabling synthetic molecularly precise fabrication. Here we demonstrate optoelectronic function in a near-to-monolayer molecular architecture approaching atomically defined spatial disposition of all components. The active layer consists of a self-assembled terrylene-based dye, forming a bicomponent supramolecular network with melamine. The assembly at the graphene-diamond interface shows an absorption maximum at 740 nm whereby the photoresponse can be measured with a gallium counter electrode. We find photocurrents of 0.5 nA and open-circuit voltages of 270 mV employing 19 mW cm−2 irradiation intensities at 710 nm. With an ex situ calculated contact area of 9.9 × 102 μm2, an incident photon to current efficiency of 0.6% at 710 nm is estimated, opening up intriguing possibilities in bottom-up optoelectronic device fabrication with molecular resolution. PMID:26911248

Potential harmful effects of dietary supplements in sports medicine.

PubMed

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.

The core-double-shell microcapsules flame retardant: Synthesis and its application for polyvinyl chloride composites

NASA Astrophysics Data System (ADS)

Zhang, Bin; Jiang, Yujie; Han, Jian

2017-12-01

The core-double-shell microcapsules flame retardant has been regarded as a promising additive for improving the fire safety of PVC. In this article, melamine-formaldehyde resin (MF)/silicon dioxide (SiO2)/zinc hydroxystannate (ZHS) microcapsule was prepared. The effect of synthetic parameters (such as pH, agitation speed, reaction time and reaction temperature) on the morphologies and sizes of the SiO2/ZHS microcapsules were investigated in details. MF/SiO2/ZHS microcapsule was introduced into PVC to prepare biofunctional composites with excellent fire resistance and smoke suppression. The flammability of PVC composites was characterized by limiting oxygen index (LOI), smoke density (SDR), cone calorimeter test. The results showed that the sample containing 16.4% MF/SiO2/ZHS microcapsule (the mass ratio of MF:SiO2:ZHS = 2.5:2:8) achieved the maximal LOI value of 35.6%, minimal SDR value of 21.2%, and significantly decreased the peak heat release rate from 179.7 kW/m2 of neat PVC to 108.3 kW/m2. The thermal behaviors of PVC composites and the morphologies of residues were characterized.

Ancient Chemistry "Pharaoh's Snakes" for Efficient Fe-/N-Doped Carbon Electrocatalysts.

PubMed

Ren, Guangyuan; Gao, Liangliang; Teng, Chao; Li, Yunan; Yang, Hequn; Shui, Jianglan; Lu, Xianyong; Zhu, Ying; Dai, Liming

2018-04-04

The method of fabricating nonprecious metal electrocatalysts with high activity and durability through a facile and eco-friendly procedure is of great significance to the development of low-cost fuel cells and metal-air batteries. Herein, we present that an ancient chemical reaction of "Pharaoh's snakes" can be a fast and convenient technique to prepare Fe-/N-doped carbon (Fe/N-C) nanosheet/nanotube electrocatalysts with sugar, soda, melamine, and iron nitrate as precursors. The resultant Fe/N-C catalyst has a hierarchically porous structure, a large surface area, and uniformly distributed active sites. The catalyst shows high electrocatalytic activities toward both the oxygen reduction reaction with a half-wave potential of 0.90 V (vs reversible hydrogen electrode) better than that of Pt/C and the oxygen evolution reaction with an overpotential of 0.46 V at the current density of 10 mA cm -2 comparable to that of RuO 2 . The activity and stability of the catalyst are also evaluated in primary and rechargeable Zn-air batteries. In both conditions, three-dimensional Fe/N-C exhibited performances superior to Pt/C. Our work demonstrates a success of utilizing an ancient science to make a state-of-the-art electrocatalyst.

High Performance of N-Doped Graphene with Bubble-like Textures for Supercapacitors.

PubMed

Zhang, Shuo; Sui, Lina; Kang, Hongquan; Dong, Hongzhou; Dong, Lifeng; Yu, Liyan

2018-02-01

Nitrogen-doped graphene (NG) with wrinkled and bubble-like texture is fabricated by a thermal treatment. Especially, a novel sonication-assisted pretreatment with nitric acid is used to further oxidize graphene oxide and its binding with melamine molecules. There are many bubble-like nanoflakes with a dimension of about 10 nm appeared on the undulated graphene nanosheets. The bubble-like texture provides more active sites for effective ion transport and reversible capacitive behavior. The specific surface area of NG (5.03 at% N) can reach up to 438.7 m 2 g -1 , and the NG electrode demonstrates high specific capacitance (481 F g -1 at 1 A g -1 , four times higher than reduced graphene oxide electrode (127.5 F g -1 )), superior cycle stability (the capacitance retention of 98.9% in 2 m KOH and 99.2% in 1 m H 2 SO 4 after 8000 cycles), and excellent energy density (42.8 Wh kg -1 at power density of 500 W kg -1 in 2 m KOH aqueous electrolyte). The results indicate the potential use of NG as graphene-based electrode material for energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synergistic effects of mica and wollastonite fillers on thermal performance of intumescent fire retardant coating

NASA Astrophysics Data System (ADS)

Zia-ul-Mustafa, M.; Ahmad, Faiz; Megat-Yusoff, Puteri S. M.; Aziz, Hammad

2015-07-01

In this study, intumescent fire retardant coatings (IFRC) were developed to investigate the synergistic effects of reinforced mica and wollastonite fillers based IFRC towards heat shielding, char expansion, char composition and char morphology. Ammonium poly-phosphate (APP) was used as acid source, expandable graphite (EG) as carbon source, melamine as blowing agent, boric acid as additive and Hardener H-2310 polyamide amine in bisphenol A epoxy resin BE-188(BPA) was used as curing agent. Bunsen burner fire test was used for thermal performance according to UL-94 for 1 h. Field Emission Scanning Electron Microscopy (FESEM) was used to observe char microstructure. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to analyse char composition. The results showed that addition of clay filler in IFRC enhanced the fire protection performance of intumescent coating. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results showed the presence of boron phosphate, silicon phosphate oxide, aluminium borate in the char that improved the thermal performance of intumescent fire retardant coating (IFRC). Resultantly, the presence of these developed compounds enhanced the Integrity of structural steel upto 500°C.

Effects of nano-sized boron nitride (BN) reinforcement in expandable graphite based in-tumescent fire retardant coating

NASA Astrophysics Data System (ADS)

Zulkurnain, E. S.; Ahmad, F.; Gillani, Q. F.

2016-08-01

The purpose of in-tumescent fire retardant coating (IFRC) is to protect substrate from fire attack by limiting heat transfer. A range of coating formulations have been prepared using Bisphenol A epoxy resin BE-188 and polyamide solidifier H-2310 as two-part binder, ammonium polyphosphate (APP) as acid source, melamine (MEL) as the blowing agent, expandable graphite (EG) as carbon source and nano-boron nitride (BN) as inorganic nano filler. The filler was used to improve the performances of the APP-EG-MEL coating. The effects of nano-BN on the char morphology and thermal degradation were investigated by fire test, thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X- ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). The results showed that by substituting or reinforcing of 4% weight percentage of nano-BN, residual weight of the char increases by 23.82% compared to APP-EG-MEL coating without filler. Higher carbon content was obtained in the char and a more compact char was produced. The results indicated that nano-BN could be used as a filler to improve thermal stability of the APP-EG-MEL coating.

Facile preparation of Ni nanowire embedded nitrogen and sulfur dual-doped carbon nanofibers and its superior catalytic activity toward urea oxidation.

PubMed

Liu, Dong; Li, Wenjia; Li, Libo; Ling, Hao; You, Tianyan

2018-06-08

A novel hairy-shaped Ni nanowire embedded nitrogen and sulfur dual-doped carbon nanofibers (Ni/N,S-CNFs) with superior electrocatalytic properties for urea oxidation reaction (UOR) was reported. The Ni/N,S-CNFs was prepared by electrospinning and carbonization process, using melamine-trithiocyanuric acid (MTCA) aggregates as both the N and S element sources. Noteworthy, MTCA also favored the formation of Ni nanowire via vapor liquid-solid mechanism, while Ni nanoparticles loaded CNFs (Ni/CNFs) was obtained without MTCA. For UOR tests, a high peak current intensity of 37.0 mA mg -1 was obtained on Ni/N,S-CNFs at 0.42 V (vs. SCE), 2-times higher of that on Ni/CNFs. Besides, the catalytic stability of Ni/N,S-CNFs was also improved. The enhanced catalytic properties of Ni/N,S-CNFs for UOR were ascribed to its unique Ni nanowires structure as well as the N, S dual-doping. Our work reveals that the property improvement of metal-based catalysts could be achieved by the heteroatom doping to fine the metal nanostructure. Copyright © 2018. Published by Elsevier Inc.

A Rapid Microwave-Assisted Thermolysis Route to Highly Crystalline Carbon Nitrides for Efficient Hydrogen Generation.

PubMed

Guo, Yufei; Li, Jing; Yuan, Yupeng; Li, Lu; Zhang, Mingyi; Zhou, Chenyan; Lin, Zhiqun

2016-11-14

Highly crystalline graphitic carbon nitride (g-C 3 N 4 ) with decreased structural imperfections benefits from the suppression of electron-hole recombination, which enhances its hydrogen generation activity. However, producing such g-C 3 N 4 materials by conventional heating in an electric furnace has proven challenging. Herein, we report on the synthesis of high-quality g-C 3 N 4 with reduced structural defects by judiciously combining the implementation of melamine-cyanuric acid (MCA) supramolecular aggregates and microwave-assisted thermolysis. The g-C 3 N 4 material produced after optimizing the microwave reaction time can effectively generate H 2 under visible-light irradiation. The highest H 2 evolution rate achieved was 40.5 μmol h -1 , which is two times higher than that of a g-C 3 N 4 sample prepared by thermal polycondensation of the same supramolecular aggregates in an electric furnace. The microwave-assisted thermolysis strategy is simple, rapid, and robust, thereby providing a promising route for the synthesis of high-efficiency g-C 3 N 4 photocatalysts. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Environmental exposures and pediatric kidney function and disease: A systematic review.

PubMed

Zheng, Laura Y; Sanders, Alison P; Saland, Jeffrey M; Wright, Robert O; Arora, Manish

2017-10-01

Environmental chemical exposures have been implicated in pediatric kidney disease. No appraisal of the available evidence has been conducted on this topic. We performed a systematic review of the epidemiologic studies that assessed association of environmental exposures with measures of kidney function and disease in pediatric populations. The search period went through July 2016. We found 50 studies that met the search criteria and were included in this systematic review. Environmental exposures reviewed herein included lead, cadmium, mercury, arsenic, fluoride, aflatoxin, melamine, environmental tobacco, bisphenol A, dental procedures, phthalates, ferfluorooctanoic acid, triclosan, and thallium/uranium. Most studies assessed environmental chemical exposure via biomarkers but four studies assessed exposure via proximity to emission source. There was mixed evidence of association between metal exposures, and other non-metal environmental exposures and pediatric kidney disease and other kidney disease biomarkers. The evaluation of causality is hampered by the small numbers of studies for each type of environmental exposure, as well as lack of study quality and limited prospective evidence. There is a need for well-designed epidemiologic studies of environmental chemical exposures and kidney disease outcomes. Copyright © 2017. Published by Elsevier Inc.

Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aziz, Hammad, E-mail: engr.hammad.aziz03@gmail.com; Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Yusoff, P. S. M. Megat

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 themore » 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.« less

Up-Conversion Y2O3:Yb(3+),Er(3+) Hollow Spherical Drug Carrier with Improved Degradability for Cancer Treatment.

PubMed

Ge, Kun; Zhang, Cuimiao; Sun, Wentong; Liu, Huifang; Jin, Yi; Li, Zhenhua; Liang, Xing-Jie; Jia, Guang; Zhang, Jinchao

2016-09-28

The rare earth hollow spheres with up-conversion luminescence properties have shown potential applications in drug delivery and bioimaging fields. However, there have been few reports for the degradation properties of rare earth oxide drug carriers. Herein, uniform and well-dispersed Y2O3:Yb(3+),Er(3+) hollow spheres (YOHSs) have been fabricated by a general Pechini sol-gel process with melamine formaldehyde colloidal spheres as template. The novel YOHSs with up-conversion luminescence has good drug loading amount and drug-release efficiency; moreover, it exhibits pH-responsive release patterns. In particular, the YOHSs sample exhibits low cytotoxicity and excellent degradable properties in acid buffer. After the sample was loaded with anticancer drug doxorubicin (DOX), the antitumor result in vitro indicates that YOHS-DOX might be effective in cancer treatment. The animal imaging test also reveals that the YOHSs drug carrier can be used as an outstanding luminescent probe for bioimaging in vivo application prospects. The results suggest that the degradable drug carrier with up-conversion luminescence may enhance the delivery efficiency of drugs and improve the cancer therapy in clinical applications.

A wearable strain sensor based on a carbonized nano-sponge/silicone composite for human motion detection.

PubMed

Yu, Xiao-Guang; Li, Yuan-Qing; Zhu, Wei-Bin; Huang, Pei; Wang, Tong-Tong; Hu, Ning; Fu, Shao-Yun

2017-05-25

Melamine sponge, also known as nano-sponge, is widely used as an abrasive cleaner in our daily life. In this work, the fabrication of a wearable strain sensor for human motion detection is first demonstrated with a commercially available nano-sponge as a starting material. The key resistance sensitive material in the wearable strain sensor is obtained by the encapsulation of a carbonized nano-sponge (CNS) with silicone resin. The as-fabricated CNS/silicone sensor is highly sensitive to strain with a maximum gauge factor of 18.42. In addition, the CNS/silicone sensor exhibits a fast and reliable response to various cyclic loading within a strain range of 0-15% and a loading frequency range of 0.01-1 Hz. Finally, the CNS/silicone sensor as a wearable device for human motion detection including joint motion, eye blinking, blood pulse and breathing is demonstrated by attaching the sensor to the corresponding parts of the human body. In consideration of the simple fabrication technique, low material cost and excellent strain sensing performance, the CNS/silicone sensor is believed to have great potential in the next-generation of wearable devices for human motion detection.

Nitrogen-rich functional groups carbon nanoparticles based fluorescent pH sensor with broad-range responding for environmental and live cells applications.

PubMed

Shi, Bingfang; Su, Yubin; Zhang, Liangliang; Liu, Rongjun; Huang, Mengjiao; Zhao, Shulin

2016-08-15

A nitrogen-rich functional groups carbon nanoparticles (N-CNs) based fluorescent pH sensor with a broad-range responding was prepared by one-pot hydrothermal treatment of melamine and triethanolamine. The as-prepared N-CNs exhibited excellent photoluminesence properties with an absolute quantum yield (QY) of 11.0%. Furthermore, the N-CNs possessed a broad-range pH response. The linear pH response range was 3.0 to 12.0, which is much wider than that of previously reported fluorescent pH sensors. The possible mechanism for the pH-sensitive response of the N-CNs was ascribed to photoinduced electron transfer (PET). Cell toxicity experiment showed that the as-prepared N-CNs exhibited low cytotoxicity and excellent biocompatibility with the cell viabilities of more than 87%. The proposed N-CNs-based pH sensor was used for pH monitoring of environmental water samples, and pH fluorescence imaging of live T24 cells. The N-CNs is promising as a convenient and general fluorescent pH sensor for environmental monitoring and bioimaging applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of orange oil microcapsules for application in textiles

NASA Astrophysics Data System (ADS)

Rossi, W.; Bonet-Aracil, M.; Bou-Belda, E.; Gisbert-Payá, J.; Wilson, K.; Roldo, L.

2017-10-01

The use of orange oil presents as an ecological alternative to chemicals, attracting the attention of the scientific community to the development of eco-friendly antimicrobials. The microencapsulation technology has been used for the application of orange oil to textiles, being an economically viable, fast and efficient method by combining core and shell materials, desirable perceptual and functional characteristics, responsible for properties related to the nature of the product and provides that the wall materials release the functional substances in a controlled manner, in addition to effectively protecting and isolating the core material from the external environment to prevent its volatilization and deterioration, increasing the stability of the oil, such as non-toxicity. Thus, to better exploit the properties of the orange essential oil applied to textile products this study presents a characterization of microcapsules of Melamine formaldehyde obtained by the interfacial polymerization method with variations of proportions of orange oil (volatile) with fixed oil Medium-Chain Triglycerides (MCT) (non-volatile) to assist in the stability of the orange essential oil. Scanning electron microscope (SEM) was used as visualizing tool to characterize microparticles and surface morphology and thermal characteristics of microcapsules were premeditated by mean Differential scanning calorimetry (DSC).

Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

NASA Astrophysics Data System (ADS)

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.

A method to determine the acoustic reflection and absorption coefficients of porous media by using modal dispersion in a waveguide.

PubMed

Prisutova, Jevgenija; Horoshenkov, Kirill; Groby, Jean-Philippe; Brouard, Bruno

2014-12-01

The measurement of acoustic material characteristics using a standard impedance tube method is generally limited to the plane wave regime below the tube cut-on frequency. This implies that the size of the tube and, consequently, the size of the material specimen must remain smaller than a half of the wavelength. This paper presents a method that enables the extension of the frequency range beyond the plane wave regime by at least a factor of 3, so that the size of the material specimen can be much larger than the wavelength. The proposed method is based on measuring of the sound pressure at different axial locations and applying the spatial Fourier transform. A normal mode decomposition approach is used together with an optimization algorithm to minimize the discrepancy between the measured and predicted sound pressure spectra. This allows the frequency and angle dependent reflection and absorption coefficients of the material specimen to be calculated in an extended frequency range. The method has been tested successfully on samples of melamine foam and wood fiber. The measured data are in close agreement with the predictions by the equivalent fluid model for the acoustical properties of porous media.

A mixture approach to the acoustic properties of a macroscopically inhomogeneous porous aluminum in the equivalent fluid approximation.

PubMed

Sacristan, C J; Dupont, T; Sicot, O; Leclaire, P; Verdière, K; Panneton, R; Gong, X L

2016-10-01

The acoustic properties of an air-saturated macroscopically inhomogeneous aluminum foam in the equivalent fluid approximation are studied. A reference sample built by forcing a highly compressible melamine foam with conical shape inside a constant diameter rigid tube is studied first. In this process, a radial compression varying with depth is applied. With the help of an assumption on the compressed pore geometry, properties of the reference sample can be modelled everywhere in the thickness and it is possible to use the classical transfer matrix method as theoretical reference. In the mixture approach, the material is viewed as a mixture of two known materials placed in a patchwork configuration and with proportions of each varying with depth. The properties are derived from the use of a mixing law. For the reference sample, the classical transfer matrix method is used to validate the experimental results. These results are used to validate the mixture approach. The mixture approach is then used to characterize a porous aluminium for which only the properties of the external faces are known. A porosity profile is needed and is obtained from the simulated annealing optimization process.

Membrane emulsification to produce perfume microcapsules

NASA Astrophysics Data System (ADS)

Pan, Xuemiao

Microencapsulation is an efficient technology to deliver perfume oils from consumer products onto the surface of fabrics. Microcapsules having uniform size/mechanical strength, may provide better release performance. Membrane emulsification in a dispersion cell followed by in-situ polymerization was used to prepare narrow size distribution melamine-formaldehyde (MF) microcapsules containing several types of oil-based fragrances or ingredients. Investigated in this study are the parameters impacting to the size and size distribution of the droplets and final MF microcapsules. A pilot plant-scale cross-flow membrane system was also used to produce MF microcapsules, demonstrating that the membrane emulsification process has potential to be scaled up for industrial applications. In this study, health and environmental friendly poly (methyl methacrylate) (PMMA) microcapsules with narrow size distribution were also prepared for the first time using the dispersion cell membrane emulsification system. Characterization methods previously used for thin-shell microcapsules were expanded to analyse microcapsules with thick shells. The intrinsic mechanical properties of thick shells were determined using a micromanipulation technique and finite element analysis (FEM). The microcapsules structure was also considered in the determination of the permeability and diffusivity of the perfume oils in good solvents..

Food safety issues in China: a case study of the dairy sector.

PubMed

Dong, Xiaoxia; Li, Zhemin

2016-01-15

Over the past 10 years, food safety incidents have occurred frequently in China. Food safety issues in the dairy sector have increasingly gained the attention of the Chinese government and the public. The objective of this research is to explore consumption changes of dairy products of different income groups after these dairy safety incidents. The research indicates that consumers' response to dairy safety risk is very intense. Dairy consumption has experienced a declining trend in recent years, and the impact of dairy safety incidents has lasted for at least 5 years. Until 2012, dairy consumption had not yet fully recovered from this influence. Using the random effects model, this study examined the relationship between food safety incident and consumption. Overall, the results show that consumers in the low-income group are more sensitive to safety risk than those in the high-income group. It can be seen from this paper that the decrease of urban residents' dairy consumption was mainly driven by changes in fresh milk consumption, while the decline of milk powder consumption, which was affected by the melamine incident, was relatively moderate, and milk powder consumption for the high-income group even increased. © 2015 Society of Chemical Industry.

Design of a new bottom antireflective coating composition for KrF resist

NASA Astrophysics Data System (ADS)

Mizutani, Kazuyoshi; Momota, Makoto; Aoai, Toshiaki; Yagihara, Morio

1999-06-01

A study for a new organic bottom antireflective coating (BARC) composition is described. A structural design of a light-absorbing dye was most important because dye structure not only plays a role in eliminating reflection from a substrate but also shows influence on dry etch rate of BARC material to a considerable extent. For example, an anthracene moiety with large absorption at 248 nm had undesirable dry etch resistance. 3-Hydroxy-2-naphthoic acid moiety was found to be one of suitable dyes for KrF BARC compositions, and the polymer bearing the dye showed enough absorbance and good erodability in dry etch. The BARC polymer was eroded as one and a half times faster than a novolak resin, and a little faster than an anthracene incorporated polymer. The result was discussed from the concepts of Ohnishi parameter and the ring parameter for dry etch durability of resist materials. BARC polymer should be thermoset by hard bake to eliminate intermixing with resist compositions. The BARC polymer bearing hydroxy group which is useful for a crosslinking reaction was thermoset in the presence of melamine-formaldehyde crosslinker and an acid catalyst after baking over 200 degrees C.

Investigation on the mechanical properties of polyurea (PU)/melamine formaldehyde (MF) microcapsules prepared with different chain extenders.

PubMed

Hu, Jianfeng; Zhang, Xiaotong; Qu, Jinqing

2018-05-02

There is lack of understanding on controlling of mechanical properties of moisture-curing PU/MF microcapsules which limited its further application. PU/MF microcapsules containing a core of isophorone diisocyanate (IPDI) were prepared with different chain extenders, polyetheramine D400, H 2 O, triethylenetetramine and polyetheramine (PEA) D230 by following a two-step synthesis method in this study. Fourier transform infra-red (FTIR) spectroscopy, Malvern particle sizing, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). And micromanipulation technique was used to identify chemical bonds in the shell, size distributions, structure, thickness, and mechanical properties of microcapsules. The results show that PU/MF microcapsules were successfully prepared. Tr increased from 46.4 ± 13.9 N/m to 75.8 ± 23.3 N/m when extender changed from D400 to D230. And the Tr increased from 51.3 ± 14.1 to 94.8 ± 17.5 N/m when the swelling time increased from 1 to 3h. Morphologies of the shell were utilised to understand the mechanism of reactions in forming the shell materials.

Citric acid based durable and sustainable flame retardant treatment for lyocell fabric.

PubMed

Mengal, Naveed; Syed, Uzma; Malik, Samander Ali; Ali Sahito, Iftikhar; Jeong, Sung Hoon

2016-11-20

Pyrovatex CP New, is a commonly used organophosphorus based flame retardant (FR) reagent for cellulosic materials. However, it has a drawback of high formaldehyde release when used with methylated melamine (MM) based cross-linker, a known carcinogenous compound. In the present approach, a durable and sustainable flame retarding recipe formulation for lyocell fabrics is developed using citric acid (CA) as a cross-linker. The FR finish was applied by pad-dry-cure process. The treated fabrics were characterized for surface morphology, elemental analysis, TG analysis, char study and FT-IR spectroscopy. Furthermore, flame retardancy, washing durability, formaldehyde release and breaking strength were also assessed, and compared with the conventional MM based FR recipe. The fabric samples treated with 400gL(-1) of FR with either 40 or 80gL(-1) of CA demonstrate flame retardancy even after 10 washing cycles. Furthermore, a 75% reduction in formaldehyde release is achieved. Higher char yield and lower decomposition temperature are found compared to untreated and FR+ MM treated lyocell. Such an improved sustainable recipe formulation can be used for lyocell fabric without any health risk in apparel wear. Copyright © 2016 Elsevier Ltd. All rights reserved.

Proceedings of the 2013 National Toxicology Program Satellite Symposium

PubMed Central

Elmore, Susan A.; Boyle, Michael C.; Boyle, Molly H.; Cora, Michelle C.; Crabbs, Torrie A.; Cummings, Connie A.; Gruebbel, Margarita M.; Johnson, Crystal L.; Malarkey, David E.; McInnes, Elizabeth F.; Nolte, Thomas; Shackelford, Cynthia C.; Ward, Jerrold M.

2014-01-01

The 2013 annual National Toxicology Program (NTP) Satellite Symposium, entitled “Pathology Potpourri” was held in Portland, Oregon in advance of the Society of Toxicologic Pathology's 32nd annual meeting. The goal of the NTP Symposium is to present current diagnostic pathology or nomenclature issues to the toxicologic pathology community. This article presents summaries of the speakers' presentations, including diagnostic or nomenclature issues that were presented, along with select images that were used for audience voting and discussion. Some lesions and topics covered during the symposium included a caudal tail vertebra duplication in mice; nephroblastematosis in rats; ectopic C cell tumor in a hamster; granular cell aggregates/tumor in the uterus of a hamster; Pneumocystis carinii in the lung of a rat; iatrogenic chronic inflammation in the lungs of control rats; hepatoblastoma arising within an adenoma in a mouse; humoral hypercalcemia of benignancy in a transgenic mouse; acetaminophen induced hepatoxicity in rats; electron microscopy images of iatrogenic intraerythrocytic inclusions in transgenic mice; questionable hepatocellular degeneration/cell death/artifact in rats; atypical endometrial hyperplasia in rats; malignant mixed Müllerian tumors/carcinosarcomas in rats; differential diagnoses of proliferative lesions the intestine of rodents; and finally obstructive nephropathy caused by melamine poisoning in a rat. PMID:24334674

Removal of organic phosphorus and formaldehyde in glyphosate wastewater by CWO and the lime-catalyzed formose reaction.

PubMed

Xing, Bo; Chen, Honglin; Zhang, Xiaoming

2017-03-01

Glyphosate (PMG) wastewater with 40-600 mg/L organic phosphorus (OP) and 1-4% CH 2 O was treated by catalytic wet oxidation (CWO) and the lime-catalyzed formose reaction to remove total phosphorus (TP) and improve biodegradability. Activated carbons (ACs) modified by H 2 O 2 oxidation and thermal treatment with melamine were used as CWO catalysts and characterized by N 2 adsorption/desorption and XPS. The CWO experiments were performed in an autoclave reactor at 110-130 °C and 1.0 MPa. The modified AC showed higher catalytic activity than the parent AC due to the introduction of nitrogen-containing functional groups, exhibited over 90% OP removal for various real PMG wastewaters, and had good stability for 20 consecutive CWO runs. The CWO effluents were further treated by lime at 80 °C to remove TP and CH 2 O. The treated effluents, containing 0.5-12 mg/L TP and 20-60 mg/L CH 2 O, showed good biodegradability with a BOD 5 /COD ratio of 0.31-0.41. The combination of CWO and lime is an effective treatment method prior to biological treatment for solving the problems of OP and CH 2 O encountered by the glyphosate industry.

Magnetic N-doped mesoporous carbon as an adsorbent for the magnetic solid-phase extraction of phthalate esters from soft drinks.

PubMed

Li, Menghua; Jiao, Caina; Yang, Xiumin; Wang, Chun; Wu, Qiuhua; Wang, Zhi

2017-04-01

A new kind of magnetic N-doped mesoporous carbon was prepared by the one-step carbonization of a hybrid precursor (glucose, melamine, and iron chloride) in a N 2 atmosphere with a eutectic salt (KCl/ZnCl 2 ) as the porogen. The obtained magnetic N-doped mesoporous carbon showed excellent characteristics, such as strong magnetic response, high surface area, large pore volume, and abundant π-electron system, which endow it with a great potential as a magnetic solid-phase extraction adsorbent. To evaluate its adsorption performance, the magnetic N-doped mesoporous carbon was used for the extraction of three phthalate esters from soft drink samples followed by high-performance liquid chromatographic analysis. Under the optimum conditions, the developed method showed a good linearity (1.0-120.0 ng/mL), low limit of detection (0.1-0.3 ng/mL, S/N = 3), and good recoveries (83.2-119.0%) in soft drink samples. The results indicated that the magnetic N-doped mesoporous carbon has an excellent adsorption capacity for phthalate esters and the present method is simple, accurate, and highly efficient for the extraction and determination of phthalate esters in complex matrix samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of experimental parameters on the microencapsulation of a photopolymerizable phase.

PubMed

Pernot, J M; Brun, H; Pouyet, B; Sergent, M; Phan-Tan-Luu, R

1993-01-01

Conditions of microencapsulation by in situ polycondensation, using melamine-formaldehyde as wall material, are influenced by the chemical nature of the core to encapsulate. In our study concerning the encapsulation of a photopolymerizable phase containing an electrically charged compound, it was necessary to modify the experimental process to obtain capsules of good quality. We used the factorial design method of screening by utilization of an asymmetric matrix, according to the collapsing principle of Addleman. The advantage of this method is that it allows determination of the simultaneous influences of the 11 experimental parameters involved in this preparation. The calculation method can be applied to more than two levels for some of the factors. The continuously varying parameters were altered between two extreme levels, chosen to allow encapsulation. For discontinuous factors, such as the molecular weight of the modifying system or nature of the aminoplast, we used the commercially available compounds, respectively three and four kinds. The results of the obtained capsules were determined by comparing microphotographic pictures. With 16 experiments we found four more factors influencing quality of capsules. We also determined the most favourable levels for the other seven parameters. The results allowed us to find optimal conditions in the experimental field. We obtained capsules of a satisfactory quality for this purpose, using only minimum experimentation.

Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

NASA Astrophysics Data System (ADS)

Amir, N.; Othman, W. M. S. W.; Ahmad, F.

2015-07-01

This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy

NASA Astrophysics Data System (ADS)

Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

2016-08-01

The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications.

One-step pyrolysis route to three dimensional nitrogen-doped porous carbon as anode materials for microbial fuel cells

NASA Astrophysics Data System (ADS)

Bi, Linlin; Ci, Suqin; Cai, Pingwei; Li, Hao; Wen, Zhenhai

2018-01-01

The design and synthesis of low-cost and favourable anode materials is crucial to both power production efficiency and overall performance of microbial fuel cells (MFCs). Herein, we reported the preparation of three dimensional (3D) nitrogen-doped porous carbons (N/PCs) by one-step pyrolysis of solid mixture of sodium citrate and melamine. a variety of techniques, including electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), etc., were applied to characterize the surface physicochemical properties of the products, featuring macroporous structure with rich nitrogen doping on the as-prepared N/PCs. When applied as anode materials of MFC, the N/PCs exhibits a maximum power density of 2777.7 mW m-2, approximately twice higher than that of the MFCs with the commercial carbon cloth (CC) as anode. The significantly improved performance of the N/PCs was attributed to the unique structure and properties, such as favourable porous structure, good electrical conductivity, and large pore volume (0.7 cm3 g-1) in the present N/PCs. Nitrogen dopant on the surface of porous carbon contributed to an increasing in biocompatibility, resulting in a suitable micro-environment for microbial growth and thus helps to decrease charge transfer resistance at the electrode interface.

A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy

PubMed Central

Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

2016-01-01

The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications. PMID:27501762

Cross-linked carbon networks constructed from N-doped nanosheets with enhanced performance for supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Qingqing; Zhong, Jialiang; Sun, Zhipeng; Mi, Hongyu

2017-02-01

Hierarchically porous carbons offer great benefits for constructing advanced electrodes for energy-related applications. Herein, we reported facile synthesis of cross-linked carbon networks (HPCNs) made from N-doped nanosheets. By using MgO as self-sacrificial templates, the polyethylene glycol and melamine precursors were first uniformly coated on the template, and then annealed at the elevated temperature in inert atmosphere before removing the templates by mild acid etching. Interestingly, the capacitance performance of HPCNs could be easily modulated by adjusting the mass ratio of the precursors and templates, as well as the carbonization temperature. The optimized HPCNs showed specific capacitances of 192.6 F g-1 at 1.0 A g-1 and 156.2 F g-1 even at 20 A g-1 in 6.0 M KOH solution, and long-term cyclability with 85.5% capacitance retention at high current load of 10 A g-1 after 8000 successive cycles, which were attributed to structural merits of these continuous networks including high surface area of 370.8 m2 g-1, high pore volume of 1.65 cm3 g-1, as well as high nitrogen content of 9.920 wt.%. Owing to simplicity of the synthesis method and superior performance, such HPCNs may promise great potential in energy storage fields.

Evaluation of direct analysis in real time for the determination of highly polar pesticides in lettuce and celery using modified Quick Polar Pesticides Extraction method.

PubMed

Lara, Francisco J; Chan, Danny; Dickinson, Michael; Lloyd, Antony S; Adams, Stuart J

2017-05-05

Direct analysis in real time (DART) was evaluated for the determination of a number of highly polar pesticides using the Quick Polar Pesticides Extraction (QuPPe) method. DART was hyphenated to high resolution mass spectrometry (HRMS) in order to get the required selectivity that allows the determination of these compounds in complex samples such as lettuce and celery. Experimental parameters such as desorption temperature, scanning speed, and distances between the DART ion source and MS inlet were optimized. Two different mass analyzers (Orbitrap and QTOF) and two accessories for sample introduction (Dip-it ® tips and QuickStrip™ sample cards) were evaluated. An extra clean-up step using primary-secondary amine (PSA) was included in the QuPPe method to improve sensitivity. The main limitation found was in-source fragmentation, nevertheless QuPPe-DART-HRMS proved to be a fast and reliable tool with quantitative capabilities for at least seven compounds: amitrole, cyromazine, propamocarb, melamine, diethanolamine, triethanolamine and 1,2,4-triazole. The limits of detection ranged from 20 to 60μg/kg. Recoveries for fortified samples ranged from 71 to 115%, with relative standard deviations <18%. Copyright © 2017 Elsevier B.V. All rights reserved.

Fingerprinting food: current technologies for the detection of food adulteration and contamination.

PubMed

Ellis, David I; Brewster, Victoria L; Dunn, Warwick B; Allwood, J William; Golovanov, Alexander P; Goodacre, Royston

2012-09-07

Major food adulteration and contamination events seem to occur with some regularity, such as the widely publicised adulteration of milk products with melamine and the recent microbial contamination of vegetables across Europe for example. With globalisation and rapid distribution systems, these can have international impacts with far-reaching and sometimes lethal consequences. These events, though potentially global in the modern era, are in fact far from contemporary, and deliberate adulteration of food products is probably as old as the food processing and production systems themselves. This review first introduces some background into these practices, both historically and contemporary, before introducing a range of the technologies currently available for the detection of food adulteration and contamination. These methods include the vibrational spectroscopies: near-infrared, mid-infrared, Raman; NMR spectroscopy, as well as a range of mass spectrometry (MS) techniques, amongst others. This subject area is particularly relevant at this time, as it not only concerns the continuous engagement with food adulterers, but also more recent issues such as food security, bioterrorism and climate change. It is hoped that this introductory overview acts as a springboard for researchers in science, technology, engineering, and industry, in this era of systems-level thinking and interdisciplinary approaches to new and contemporary problems.

Study of the Thermal Properties and the Fire Performance of Flame Retardant-Organic PCM in Bulk Form

PubMed Central

Palacios, Anabel; De Gracia, Alvaro

2018-01-01

The implementation of organic phase change materials (PCMs) in several applications such as heating and cooling or building comfort is an important target in thermal energy storage (TES). However, one of the major drawbacks of organic PCMs implementation is flammability. The addition of flame retardants to PCMs or shape-stabilized PCMs is one of the approaches to address this problem and improve their final deployment in the building material sector. In this study, the most common organic PCM, Paraffin RT-21, and fatty acids mixtures of capric acid (CA), myristic acid (MA), and palmitic acid (PA) in bulk, were tested to improve their fire reaction. Several flame retardants, such as ammonium phosphate, melamine phosphate, hydromagnesite, magnesium hydroxide, and aluminum hydroxide, were tested. The properties of the improved PCM with flame retardants were characterized by thermogravimetric analyses (TGA), the dripping test, and differential scanning calorimetry (DSC). The results for the dripping test show that fire retardancy was considerably enhanced by the addition of hydromagnesite (50 wt %) and magnesium hydroxide (50 wt %) in fatty acids mixtures. This will help the final implementation of these enhanced PCMs in building sector. The influence of the addition of flame retardants on the melting enthalpy and temperatures of PCMs has been evaluated. PMID:29329212

Industrially benign super-compressible piezoresistive carbon foams with predefined wetting properties: from environmental to electrical applications

NASA Astrophysics Data System (ADS)

Pham, Tung Ngoc; Samikannu, Ajaikumar; Kukkola, Jarmo; Rautio, Anne-Riikka; Pitkänen, Olli; Dombovari, Aron; Lorite, Gabriela Simone; Sipola, Teemu; Toth, Geza; Mohl, Melinda; Mikkola, Jyri-Pekka; Kordas, Krisztian

2014-11-01

In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ~4 m2g-1 to ~345 m2g-1, while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ~40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (>70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 +/- 0.07), while piezoresistive measurements show very high gauge factors (from ~20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

Industrially benign super-compressible piezoresistive carbon foams with predefined wetting properties: from environmental to electrical applications.

PubMed

Pham, Tung Ngoc; Samikannu, Ajaikumar; Kukkola, Jarmo; Rautio, Anne-Riikka; Pitkänen, Olli; Dombovari, Aron; Lorite, Gabriela Simone; Sipola, Teemu; Toth, Geza; Mohl, Melinda; Mikkola, Jyri-Pekka; Kordas, Krisztian

2014-11-06

In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ~4 m(2)g(-1) to ~345 m(2)g(-1), while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ~40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (>70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 ± 0.07), while piezoresistive measurements show very high gauge factors (from ~20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

Encapsulated Vanadium-Based Hybrids in Amorphous N-Doped Carbon Matrix as Anode Materials for Lithium-Ion Batteries.

PubMed

Long, Bei; Balogun, Muhammad-Sadeeq; Luo, Lei; Luo, Yang; Qiu, Weitao; Song, Shuqin; Zhang, Lei; Tong, Yexiang

2017-11-01

Recently, researchers have made significant advancement in employing transition metal compound hybrids as anode material for lithium-ion batteries and developing simple preparation of these hybrids. To this end, this study reports a facile and scalable method for fabricating a vanadium oxide-nitride composite encapsulated in amorphous carbon matrix by simply mixing ammonium metavanadate and melamine as anode materials for lithium-ion batteries. By tuning the annealing temperature of the mixture, different hybrids of vanadium oxide-nitride compounds are synthesized. The electrode material prepared at 700 °C, i.e., VM-700, exhibits excellent cyclic stability retaining 92% of its reversible capacity after 200 cycles at a current density of 0.5 A g -1 and attractive rate performance (220 mAh g -1 ) under the current density of up to 2 A g -1 . The outstanding electrochemical properties can be attributed to the synergistic effect from heterojunction form by the vanadium compound hybrids, the improved ability of the excellent conductive carbon for electron transfer, and restraining the expansion and aggregation of vanadium oxide-nitride in cycling. These interesting findings will provide a reference for the preparation of transition metal oxide and nitride composites as well. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Emission of organic substances from chip-boards].

PubMed

Deppe, H J

1982-01-01

A relatively small number of investigations on emissions of organic substances from chip-board is available up to now. The emissions known to date are caused by glues or other additives rather than by the wood itself. As concerns aminoplast glues (urea-formaldehyde or melamine-formaldehyde resins) the most important point of public interest has been the off-gassing of formaldehyde from chip-board. Chip-board with phenol-formaldehyde glues has been known in some cases to give off phenol. The formation of diamino diphenyl methane from isocyanate glues is still a matter of discussion. A further source for possible emissions are wood and fire protectives which are added during the manufacturing process. Finally, coating of chip-board may lead to emissions of organic substances. The lack of adequate detection methods has so far delayed the treatment of questions in relation to emissions from chip-board. Even now, there are numerous problems in this field especially when investigating isocyanate glues. Problems in relation to the origin of emissions due to the kind of glue used and the manufacturing process are discussed, and proposals are made how to solve some of these problems. The question of the health risk is dealt with from the view-point of the civil engineer and in an general economic context.

Nitrogen doped activated carbon from pea skin for high performance supercapacitor

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Ahmed, Ahsan; Rafat, M.

2018-04-01

In this work, nitrogen doped porous carbon (NDC) has been synthesized employing a facile two-step process. Firstly, carbon precursor (pea skin) was heated with melamine (acting as nitrogen source) followed by activation with KOH in different ratios. The dependence of porosity and nitrogen content on impregnation ratio was extensively studied. Other textural properties of prepared NDC sample were studied using standard techniques of material characterization. The electrochemical performance of NDC sample as an electrode was studied in two-electrode symmetric supercapacitor system. 1 M LiTFSI (lithium bis-trifluoromethanesulfonimide) solution in IL EMITFSI (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), was used as electrolyte. It was found that the fabricated supercapacitor cell offers high values of specific capacitance (141.1 F g‑1), specific energy (19.6 Wh kg‑1) and specific power (25.4 kW kg‑1) at current density of 1.3 A g‑1. More importantly, the fabricated supercapacitor cell shows capacitance retention of ∼75%, for more than 5000 cycles. The enhanced performance of NDC sample is primarily due to large surface area with favorable surface structure (contributing to double layer capacitance) and presence of nitrogen functionalities (contributing to pseudo-capacitance). Such important features make the synthesized NDC sample, an attractive choice for electrode material in high performance supercapacitor.

Impact of polymer surface characteristics on the microrheological measurement quality of protein solutions - A tracer particle screening.

PubMed

Bauer, Katharina Christin; Schermeyer, Marie-Therese; Seidel, Jonathan; Hubbuch, Jürgen

2016-05-30

Microrheological measurements prove to be suitable to identify rheological parameters of biopharmaceutical solutions. These give information about the flow characteristics but also about the interactions and network structures in protein solutions. For the microrheological measurement tracer particles are required. Due to their specific surface characteristic not all are suitable for reliable measurement results in biopharmaceutical systems. In the present work a screening of melamine, PMMA, polystyrene and surface modified polystyrene as tracer particles were investigated at various protein solution conditions. The surface characteristics of the screened tracer particles were evaluated by zeta potential measurements. Furthermore each tracer particle was used to determine the dynamic viscosity of lysozyme solutions by microrheology and compared to a standard. The results indicate that the selection of the tracer particle had a strong impact on the quality of the microrheological measurement dependent on pH and additive type. Surface modified polystyrene was the only tracer particle that yielded good microrheological results for all tested conditions. The study indicated that the electrostatic surface charge of the tracer particle had a minor impact than its hydrophobicity. This characteristic was the crucial surface property that needs to be considered for the selection of a suitable tracer particle to achieve high measurement accuracy. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of red mud-epoxy intumescent char using surface imaging and micro analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arogundade, A. I., E-mail: ajiunolorioba@gmail.com; Megat-Yusoff, P. S. M., E-mail: puteris@petronas.com.my; Faiz, A.

In this study, red mud (RM), an oxide waste was proposed as reinforcing, synergistic filler for the traditional epoxy intumescent coating (IC). 5.5 wt% of acid-modified and unmodified red mud were introduced into the basic intumescent formulation of ammonium polyphosphate (APP), pentaerythritol (PER) and melamine (MEL). In order to predict effect of modification on its suitability, Field emission electron scanning microscopy and Fourier transform infra red were used to obtain detailed characteristics such as the cell size, pore distribution, homogeneity and chemical composition of the red mud-epoxy carbonaceous char. Both acid-modified and unmodified RM-filled ICs produced chars with smaller andmore » more closely packed cells compared to chars from the unfilled coating. Both coating types had hard carbonaceous metal phosphate coverings that could act as heat barriers. The unmodified red mud was found to be antagonistic to the intumescent action with an expansion of only 2 times the initial thickness. The leached, low iron-red mud produced an expansion of 15 times the initial thickness, but possessed a hollow interior. From these findings, it may be deduced that while acid leaching of red mud may improve intumescent expansion, it would be necessary to optimize the percent filler loading to improve residual mass.« less

Atomic-Level Co3O4 Layer Stabilized by Metallic Cobalt Nanoparticles: A Highly Active and Stable Electrocatalyst for Oxygen Reduction.

PubMed

Liu, Min; Liu, Jingjun; Li, Zhilin; Wang, Feng

2018-02-28

Developing atomic-level transition oxides may be one of the most promising ways for providing ultrahigh electrocatalytic performance for oxygen reduction reaction (ORR), compared with their bulk counterparts. In this article, we developed a set of atomically thick Co 3 O 4 layers covered on Co nanoparticles through partial reduction of Co 3 O 4 nanoparticles using melamine as a reductive additive at an elevated temperature. Compared with the original Co 3 O 4 nanoparticles, the synthesized Co 3 O 4 with a thickness of 1.1 nm exhibits remarkably enhanced ORR activity and durability, which are even higher than those obtained by a commercial Pt/C in an alkaline environment. The superior activity can be attributed to the unique physical and chemical structures of the atomic-level oxide featuring the narrowed band gap and decreased work function, caused by the escaped lattice oxygen and the enriched coordination-unsaturated Co 2+ in this atomic layer. Besides, the outstanding durability of the catalyst can result from the chemically epitaxial deposition of the Co 3 O 4 on the cobalt surface. Therefore, the proposed synthetic strategy may offer a smart way to develop other atomic-level transition metals with high electrocatalytic activity and stability for energy conversion and storage devices.

Solid-Phase Synthesis of Molecularly Imprinted Polymer Nanoparticles with a Reusable Template - "Plastic Antibodies".

PubMed

Poma, Alessandro; Guerreiro, Antonio; Whitcombe, Michael J; Piletska, Elena V; Turner, Anthony P F; Piletsky, Sergey A

2013-06-13

Molecularly Imprinted Polymers (MIPs) are generic alternatives to antibodies in sensors, diagnostics and separations. To displace biomolecules without radical changes in infrastructure in device manufacture, MIPs should share their characteristics (solubility, size, specificity and affinity, localized binding domain) whilst maintaining the advantages of MIPs (low-cost, short development time and high stability) hence the interest in MIP nanoparticles. Herein we report a reusable solid-phase template approach (fully compatible with automation) for the synthesis of MIP nanoparticles and their precise manufacture using a prototype automated UV photochemical reactor. Batches of nanoparticles (30-400 nm) with narrow size distributions imprinted with: melamine (d = 60 nm, K d = 6.3 × 10 -8 m), vancomycin (d = 250 nm, K d = 3.4 × 10 -9 m), a peptide (d = 350 nm, K d = 4.8 × 10 -8 m) and proteins have been produced. Our instrument uses a column packed with glass beads, bearing the template. Process parameters are under computer control, requiring minimal manual intervention. For the first time we demonstrate the reliable re-use of molecular templates in the synthesis of MIPs (≥ 30 batches of nanoMIPs without loss of performance). NanoMIPs are produced template-free and the solid-phase acts both as template and affinity separation medium.

Biomimetic Silica Nanoparticles Prepared by a Combination of Solid-Phase Imprinting and Ostwald Ripening.

PubMed

Piletska, Elena; Yawer, Heersh; Canfarotta, Francesco; Moczko, Ewa; Smolinska-Kempisty, Katarzyna; Piletsky, Stanislav S; Guerreiro, Antonio; Whitcombe, Michael J; Piletsky, Sergey A

2017-09-14

Herein we describe the preparation of molecularly imprinted silica nanoparticles by Ostwald ripening in the presence of molecular templates immobilised on glass beads (the solid-phase). To achieve this, a seed material (12 nm diameter silica nanoparticles) was incubated in phosphate buffer in the presence of the solid-phase. Phosphate ions act as a catalyst in the ripening process which is driven by differences in surface energy between particles of different size, leading to the preferential growth of larger particles. Material deposited in the vicinity of template molecules results in the formation of sol-gel molecular imprints after around 2 hours. Selective washing and elution allows the higher affinity nanoparticles to be isolated. Unlike other strategies commonly used to prepare imprinted silica nanoparticles this approach is extremely simple in nature and can be performed under physiological conditions, making it suitable for imprinting whole proteins and other biomacromolecules in their native conformations. We have demonstrated the generic nature of this method by preparing imprinted silica nanoparticles against targets of varying molecular mass (melamine, vancomycin and trypsin). Binding to the imprinted particles was demonstrated in an immunoassay (ELISA) format in buffer and complex media (milk or blood plasma) with sub-nM detection ability.