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Haihong Zhong, Yun Luo, Shi He, Pinggui Tang, Dianqing Li, Nicolas Alonso-Vante, Yongjun Feng
A metal organic framework (MOF), synthesized from cobalt salt, melamine (mela) and 1,4-dicarboxybezene (BDC), was used as precursor to prepare Co/CoNx/N-CNT/C electrocatalyst via heat-treatment (HT) at different temperature (700 - 900 °C) under nitrogen atmosphere. Crystallites size and micro-strain in the 800°C heat-treated sample (MOFs-800) were the lowest, whereas the stacking fault value was the highest, among the rest of the home-made samples, as attested by the Williamson-Hall analysis, hence assessing that the structural or/and surface modification of Co nanoparticles (NPs), found in MOFs-800, was different from other samples...
December 29, 2016: ACS Applied Materials & Interfaces
Wei-De Zhang, Feng-Yun Su
Carbonyl-grafted g-C3N4 porous nanosheets (COCNPNS) were fabricated by a two-step thermal process using melamine and oxalic acid as starting reagents. Combination of melamine with oxalic acid to form melamine-oxalic acid supramolecule as a precursor is the key to synthesize carbonyl-grafted g-C3N4. The bulk carbonyl-grafted g-C3N4 (COCN) was further thermally etched to porous nanosheets by O2 in air. In such a process, the carbonyls were partly removed and the obtained sample showed remarkably enhanced visible light harvesting and promoted separation and transfer of photo-generated electrons and holes...
December 27, 2016: Chemistry, An Asian Journal
Shujin Hou, Miao Wang, Xingtao Xu, Yandong Li, Yanjiang Li, Ting Lu, Likun Pan
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...
December 19, 2016: Journal of Colloid and Interface Science
Riccardo Suter, Yanbo Mei, Matthew Baker, Zoltan Benkő, Zhongshu Li, Hansjörg Grützmacher
Cyanuric acid (C3 H3 N3 O3 ) is widely used as cross-linker in basic polymers (often in combination with other crosslinking agents like melamine) but also finds application in more sophisticated materials such as in supramolecular assemblies and molecular sheets. The unknown phosphorus analogue of cyanuric acid, P3 C3 (OH)3 , may become an equally useful building block for phosphorus-based polymers or materials which have unique properties. Herein we describe a straightforward synthesis of 2,4,6-tri(hydroxy)-1,3,5-triphosphinine and its derivatives P3 C3 (OR)3 which have been applied as strong π-acceptor η(6) -ligands in piano stool Mo(CO)3 complexes...
December 27, 2016: Angewandte Chemie
Huiling Zhao, Yinli Li, Dong Chen, Bo Liu
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...
December 2016: Nanoscale Research Letters
Shiru Liang, Hongyuan Yan, Jiankun Cao, Yehong Han, Shigang Shen, Ligai Bai
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...
January 25, 2017: Analytica Chimica Acta
Hamed Heidari, Guadalupe Rivero, Hosni Idrissi, Dhanya Ramachandran, Seda Cakir, Ricardo Egoavil, Mert Kurttepeli, Amandine C Crabbé, Tom Hauffman, Herman Terryn, Filip Du Prez, Dominique Schryvers
A systematic study has been carried out to compare the surface morphology, shell thickness, mechanical properties, and binding behavior of melamine-formaldehyde microcapsules of 5-30 μm diameter size with various amounts of core content by using scanning and transmission electron microscopy including electron tomography, in situ nanomechanical tensile testing, and electron energy-loss spectroscopy. It is found that porosities are present on the outside surface of the capsule shell, but not on the inner surface of the shell...
December 2016: Microscopy and Microanalysis
Jiajie Li, Yumin Zhang, Xinghong Zhang, Jinzhen Huang, Jiecai Han, Zhihua Zhang, Xijiang Han, Ping Xu, Bo Song
Replacement of rare and precious metal catalysts with low-cost and earth-abundant ones is currently among the major goals of sustainable chemistry. Herein, we report the synthesis of S, N dual-doped graphene-like carbon nanosheets via a simple pyrolysis of a mixture of melamine and dibenzyl sulfide as efficient metal-free electrocatalysts for oxygen reduction reaction (ORR). The S, N dual-doped graphene-like carbon nanosheets show enhanced activity toward ORR as compared with mono-doped counterparts, and excellent durability in contrast to the conventional Pt/C electrocatalyst in both alkaline and acidic media...
December 27, 2016: ACS Applied Materials & Interfaces
Yongjie Ma, Wenbin Dong, Hongliang Bao, Yue Fang, Cheng Fan
This paper proposed a nonlinear chemical fingerprint method for simultaneous determination of urea and melamine in milk powder using "H(+)+Ce(4+)+BrO3(-)+malonic acid" as reaction system. A multiple linear relationship was obtained between the adulterants content in milk powder and inductive time of corresponding mixed milk powder. System analysis model established with classical least squares (CLS) method was then used to calculate the content of urea and melamine in milk powder. The method was successfully applied to milk powder samples and had good recoveries in the range of 99...
April 15, 2017: Food Chemistry
M Faraji, M Adeli
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...
April 15, 2017: Food Chemistry
Carina F Nascimento, Poliana M Santos, Edenir Rodrigues Pereira-Filho, Fábio R P Rocha
Milk adulteration is a current fraudulent practice to mask the quality parameters (e.g. protein and fat content) and increase the product shelf life. Milk adulteration includes addition of toxic substances, such as formaldehyde, hydrogen peroxide, hypochlorite, dichromate, salicylic acid, melamine, and urea. In order to assure the food safety and avoid health risks to consumers, novel analytical procedures have been proposed for detection of these adulterants. The innovations encompass sample pretreatment and improved detection and data processing, including chemometric tools...
April 15, 2017: Food Chemistry
Haitao Wang, Wei Wang, Mengxi Gui, Muhammad Asif, Zhengyun Wang, Yang Yu, Junwu Xiao, Hongfang Liu
Developing a facile strategy to synthesize an efficient and inexpensive catalyst for the oxygen reduction reaction (ORR) is critical to the commercialization of many sustainable energy storage and conversion techniques. Herein, a novel and convenient strategy was presented to prepare Fe3O4 embedded into nitrogen-doped mesoporous carbon spheres (Fe3O4/N-MCS) by the polycondensation between methylolmelamines and ammonium ferric citrate (AFC) and subsequent pyrolysis process. In particular, the polycondensation reaction was completely finished within a very short time (6...
December 23, 2016: ACS Applied Materials & Interfaces
Wei Ai, Xuewan Wang, Chenji Zou, Zhuzhu Du, Zhanxi Fan, Hua Zhang, Peng Chen, Ting Yu, Wei Huang
Hierarchically porous carbons are attracting tremendous attention in sustainable energy systems, such as lithium ion battery (LIB) and fuel cell, due to their excellent transport properties that arise from the high surface area and rich porosity. The state-of-the-art approaches for synthesizing hierarchically porous carbons normally require chemical- and/or template-assisted activation techniques, which is complicate, time consuming, and not feasible for large scale production. Here, a molecular-level design principle toward large-scale synthesis of nitrogen and phosphorus codoped hierarchically porous carbon (NPHPC) through an in situ self-activation process is proposed...
December 14, 2016: Small
Shiva Gupata, Shuai Zhao, Ogechi Ogoke, Ye Lin, Hui Xu, Gang Wu
Structures and morphologies of Fe-N-C catalysts have been believed crucial for the number of active sites and local bonding structures, therefore governing overall catalyst performance for the oxygen reduction reaction (ORR). The relevant knowledge is still lacking for the rational catalyst design. Through combining different nitrogen/carbon precursors, including polyaniline (PANI), dicyandiamide (DCDA), and melamine (MLMN), we aim to tune catalyst morphology and structure for facilitating the ORR. Instead of commonly studied single precursors, multiple precursors during the synthesis provide a new opportunity to promote catalyst activity and stability via a likely synergistic effect...
December 9, 2016: ChemSusChem
Qinmin Zheng, David P Durkin, Justin E Elenewski, Yingxue Sun, Nathan A Banek, Likun Hua, Hanning Chen, Michael J Wagner, Wen Zhang, Danmeng Shuai
Graphitic carbon nitride (g-C3N4) has recently emerged as a promising visible-light-responsive polymeric photocatalyst; however, a molecular-level understanding of material properties and its application for water purification were underexplored. In this study, we rationally designed nonmetal doped, supramolecule-based g-C3N4 with improved surface area and charge separation. Density functional theory (DFT) simulations indicated that carbon-doped g-C3N4 showed a thermodynamically stable structure, promoted charge separation, and had suitable energy levels of conduction and valence bands for photocatalytic oxidation compared to phosphorus-doped g-C3N4...
December 6, 2016: Environmental Science & Technology
Takahiro Kyoya, Masami Hori, Megumi Terada
The Pig-a assay is a new in vivo genotoxicity test for detecting mutagens in the bodies of animals, using the endogenous Pig-a gene as the target. There are two types of Pig-a assays: the red blood cell (RBC) Pig-a assay, which uses RBCs, and the PIGRET assay, which uses reticulocytes. The Japanese Environmental Mutagen Society-Mammalian Mutagenicity Study Group collaborative study of the Pig-a assay was carried out to investigate the usefulness of the PIGRET assay. The mutagenicity of melamine was evaluated as part of this study...
November 15, 2016: Mutation Research
Yuyuan Zhang, Ashley A Beckstead, Yuesong Hu, Xijun Piao, Dennis Bong, Bern Kohler
Melamine may have been an important prebiotic information carrier, but its excited-state dynamics, which determine its stability under UV radiation, have never been characterized. The ability of melamine to withstand the strong UV radiation present on the surface of the early Earth is likely to have affected its abundance in the primordial soup. Here, we studied the excited-state dynamics of melamine (a proto-nucleobase) and its lysine derivative (a proto-nucleoside) using the transient absorption technique with a UV pump, and UV and infrared probe pulses...
November 30, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Roger Meder, Wolfgang Stahl, Paul Warburton, Sam Woolley, Scott Earnshaw, Klaus Haselhofer, Ken van Langenberg, Nick Ebdon, Roger Mulder
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...
December 3, 2016: Analytical and Bioanalytical Chemistry
Shreedhar Gautam, Bhagwan S Batule, Hyo Yong Kim, Ki Soo Park, Hyun Gyu Park
Rapid and accurate on-site wireless measurement of hazardous molecules or biomarkers is one of the biggest challenges in nanobiotechnology. We herein describe a novel smartphone-based Portable and Wireless Optical System (PAWS) for rapid, quantitative, and on-site analysis of target analytes. 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...
December 1, 2016: Biotechnology Journal
T Rairat, S C Ou, S K Chang, K P Li, T W Vickroy, C C Chou
The study was designed to characterize the plasma pharmacokinetics and tissue depletion profiles (including eggs) of cyromazine (CYR) in chickens following oral administration alone or in combination with melamine (MEL). In order to assess the pharmacokinetic profile of CYR, chickens were administered 1 or 10 mg/kg (single oral doses), whereas residue studies were conducted in chickens fed CYR alone (5 or 10 mg/kg) or CYR (5 mg/kg) and MEL (5 mg/kg) for a period of 14 days. Estimates for the apparent volume of distribution (1...
November 29, 2016: Journal of Veterinary Pharmacology and Therapeutics
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