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Nan Gao, Pengcheng Huang, Fangying Wu
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...
November 8, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Suphatchaya Lamkhao, Gobwute Rujijanagul, Chamnan Randorn
The visible light driven photoactivity of g-C3N4 can be enhanced using charcoal as a supporter. Charcoal/g-C3N4 composite materials were prepared by the simultaneous thermal condensation of melamine and charcoal. The effect of different atmospheres (O2, air, and argon) on the reaction was investigated. The effect of different weight ratios of charcoal to melamine (1:1 and 1:4 wt%) was also investigated. The physical properties of the charcoal/g-C3N4 materials were analyzed using XRD, SEM, TEM, XPS, BET and FTIR techniques...
November 6, 2017: Chemosphere
Xiaoliang Fang, Jianpin Tan, Yang Gao, Yongfeng Lu, Fuzhen Xuan
Strain sensors with a large strain sensing range and high sensitivity are in high demand due to their various potential applications ranging from human motion detection to soft robotics. In this study, high-performance strain sensors are developed by fragmenting carbonized melamine sponges that are commercially available. The strain sensors, based on fragmented carbonized melamine sponges (FCMS), demonstrate high sensitivity with a gauge factor (GF) of 18.7 at an FCMS density of 1.07 mg cm(-2) and a large strain sensing range of up to 80%...
November 10, 2017: Nanoscale
Vladimir V Korolkov, Ivan G Timokhin, Rolf Haubrichs, Emily F Smith, Lixu Yang, Sihai Yang, Neil R Champness, Martin Schröder, Peter H Beton
The limited stability of the surface of black phosphorus (BP) under atmospheric conditions is a significant constraint on the exploitation of this layered material and its few layer analogue, phosphorene, as an optoelectronic material. Here we show that supramolecular networks stabilised by hydrogen bonding can be formed on BP, and that these monolayer-thick films can passivate the BP surface and inhibit oxidation under ambient conditions. The supramolecular layers are formed by solution deposition and we use atomic force microscopy to obtain images of the BP surface and hexagonal supramolecular networks of trimesic acid and melamine cyanurate (CA...
November 9, 2017: Nature Communications
Zhiyong Zhao, Lei Chen, Bing Bai, Xianli Yang, Yanglan Tan, Jianhua Wang, Xiaoyan Zhao, Changyan Zhou
Providing guidance on the reasonable use of pesticide in agricultural production is of particular importance for ensuring food safety. In the present study, a field trial was performed to study the dissipation and accumulative pattern of cyromazine (CA) and its metabolite in Agaricus bisporus (A. bisporus) cultivation. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was first developed and validated for the determination of CA and melamine (MEL) in the casing soil and fruiting body...
November 8, 2017: Environmental Science and Pollution Research International
Víctor Alonso García Londoño, Martín Puñales, Marcela Reynoso, Silvia Resnik
Forty samples of milk powder purchased in Uruguay were analysed to assess melamine levels. Trichloroacetic acid and acetonitrile were used to extract and precipitate milk proteins previously to clean up of the samples by solid-phase extraction and then were determined by liquid chromatography coupled to ultraviolet detection. The limits of detection and quantification of melamine were 0.006 mg kg(-1) and 0.019 mg kg(-1), respectively. Milk was fortified with melamine at three levels, producing average recoveries higher than 83...
November 6, 2017: Food Additives & Contaminants. Part B, Surveillance
Laurent Billon, Hongyao Yin, Yujun Feng
Amphiphilic copolymers are widely used in fabricating hierarchically honeycomb-structured films via "breath figure" (BF) process as the hydrophilic block plays a key role in stabilizing water templating. However, the hydrophilic blocks reported are mainly confined to acrylic acid and its derivatives, the additional functions introduction on porous films, and the polymer composition/film microstructure relationship was less documented. In this work, a novel melamine-based hydrophilic moiety was incorporated to polystyrene chains by combining atom transfer radical polymerization and post modification to afford end-functionalized polystyrenes (PS-PANME)...
November 4, 2017: Chemistry: a European Journal
Xiang-Jin Kong, Chao Zheng, Yao-Han Lan, Shuai-Shuai Chi, Qian Dong, Hao-Long Liu, Chao Peng, Lin-Yi Dong, Liang Xu, Xian-Hua Wang
In this work, we reported an effective method for the synthesis of a multirecognition magnetic molecularly imprinted polymer (MMIP) with atom transfer radical polymerization (ATRP), using 2,4-diamino-6-methyl-1,3,5-triazine as pseudo-template. The resulting MMIP was characterized in detail by Fourier transform-infrared (FT-IR) spectra, scanning electron microscopy (SEM), thermogravimetic analysis (TGA), and vibrating sample magnetometry (VSM). These results indicated the successful synthesis of MMIP with sufficient thermal stability and magnetic properties...
November 2, 2017: Analytical and Bioanalytical Chemistry
Yi Feng, Yayan Wang, Yaquan Wang, Xiong-Fei Zhang, Jianfeng Yao
Sodium alginate-melamine sponge composites were fabricated by in-situ gelation of sodium alginate supported on the commercial melamine sponge (MS). MS serves as the three-dimensional skeleton for alginate coating and can effectively avoid the shrink of alginate, and thus makes the alginate-MS composites user-friendly and facile to recover. In the adsorption test, the adsorption process is pseudo-second order and matches the Langmuir model with the maximum adsorption capacity of 90.1mg/g for copper ions. The alginate-MS is recyclable and presents enhanced mechanical properties compared with those of pristine MS...
October 12, 2017: Journal of Colloid and Interface Science
Habib Bagheri, Shakiba Zeinali, Mohammad Yahya Baktash
Superhydrophobic materials have attracted many attentions in recent years while their application in sample preparation remained almost intact. In this project, a rough surface of melamine formaldehyde foam was silanized by chemical deposition of trichloromethylsilane to form a highly porous and superhydrophobic material, presumably a suitable medium for extracting non-polar compounds such as benzene and its methyl derivatives. The prepared sorbent was packed in a needle for the headspace needle-trap microextraction of benzene, toluene, ethylbenzene and xylenes (BTEX)...
October 6, 2017: Journal of Chromatography. A
Li-An Wu, Wei-En Li, Ding-Zheng Lin, Yih-Fan Chen
We demonstrate three-dimensional surface-enhanced Raman spectroscopy (SERS) substrates formed by accumulating plasmonic nanostructures that are synthesized using a DNA-assisted assembly method. We densely immobilize Au nanoparticles (AuNPs) on polymer beads to form core-satellite nanostructures for detecting molecules by SERS. The experimental parameters affecting the AuNP immobilization, including salt concentration and the number ratio of the AuNPs to the polymer beads, are tested to achieve a high density of the immobilized AuNPs...
October 12, 2017: Scientific Reports
Feng Chen, Basudev Sahoo, Carsten Kreyenschulte, Henrik Lund, Min Zeng, Lin He, Kathrin Junge, Matthias Beller
Nitrogen modified cobalt catalysts supported on carbon were prepared by pyrolysis of the mixture generated from cobalt(ii) acetate in aqueous solution of melamine or waste melamine resins, which are widely used as industrial polymers. The obtained nanostructured materials catalyze the transfer hydrogenation of N-heteroarenes with formic acid in the absence of base. The optimal Co/Melamine-2@C-700 catalyst exhibits high activity and selectivity for the dehydrogenation of formic acid into molecular hydrogen and carbon dioxide and allows for the reduction of diverse N-heteroarenes including substrates featuring sensitive functional groups...
September 1, 2017: Chemical Science
Theodoros Chatzimitakos, Victoria Samanidou, Constantine D Stalikas
The study describes the functionalization of melamine sponges with graphene and its use as an adsorbent for the microextraction of sulfonamides from food and environmental samples. The graphene-functionalized melamine sponge (GMeS) was prepared by an easy, one-step procedure, which complies with the principles of green chemistry and is proved advantageous over previously described methods. The applicability of the GMeS in extraction procedures was studied and an analytical method for the determination of sulfonamides in milk, eggs and lake water was developed and validated according to SANCO/12571/2013 guideline...
September 20, 2017: Journal of Chromatography. A
Onur Durucan, Tomas Rindzevicius, Michael Stenbæk Schmidt, Marco Matteucci, Anja Boisen
We present a simple, robust, and automated molecule extraction technique based on a centrifugal microfluidic platform. Fast and facile extraction of a food adulterant (melamine) from a complex sample medium (milk) on a SERS substrate is demonstrated. The unique characteristic of the detection method is the obtained "filter paper/chromatographic" effect which combines centrifugal force and wetting properties of the SERS substrate. The work addresses issues related to SERS-based detection of analytes in complex media, which is important for realizing next generation SERS platforms applicable for a broad variety of real-life applications...
October 27, 2017: ACS Sensors
Chengcheng Gu, Panpan Gai, Ting Hou, Haiyin Li, Changhui Xue, Feng Li
Enzymatic fuel cell (EFC)-based self-powered biosensors have attracted considerable attention because of their unique feature of no need for extra power sources during the entire detection process, which endows them with the merits of simplicity, rapidness, low cost, anti-interference, and ease of use. Herein, we proposed, for the first time, an EFC-based self-powered homogeneous immunosensing platform by integrating the target-induced biofuel release and bioconjugate immunoassay for ultrasensitive melamine (ME) detection...
October 18, 2017: ACS Applied Materials & Interfaces
Fatemeh Jiryaei Sharahi, Afsaneh Shahbazi
Magnetic Fe3O4 nanoparticles with an average diameter of 64 nm was synthesized solvothermically and subsequently modified with melamine-based dendrimer amine (MDA-Fe3O4) via grafting method. The synthesized materials were characterized using DLS, SEM, XRD, FTIR, VSM, TGA and elemental analysis techniques. The MDA-Fe3O4 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...
September 14, 2017: Chemosphere
Haiping Su, Yanping Chong, Jitong Wang, Donghui Long, Wenming Qiao, Licheng Ling
Hierarchical porous carbon monoliths with a 3D framework were synthesized through a facile sol-gel process using resorcinol-melamine-formaldehyde (RMF) as carbon precursors, and nanocrystalline celluloses (NCCs) as the structural inducing agent, followed by ambient pressure drying and carbonization. Polymerization of the RMF resin occurs around the nanorod-like NCCs dispersed homogeneously in water, which is quite beneficial for the formation of an interconnected network and supports the rigid macroporous structure...
January 15, 2018: Journal of Colloid and Interface Science
Chia-Chu Liu, Tusty-Jiuan Hsieh, Chia-Fang Wu, Yi-Chun Tsai, Shu-Pin Huang, Yung-Chin Lee, Tsung-Yi Huang, Jung-Tsung Shen, Yii-Her Chou, Chun-Nung Huang, Wen-Jeng Wu, Ming-Tsang Wu
Environmental low-dose melamine exposure has been associated with urolithiasis risk in adults, but it is unclear if this exposure can cause early renal damage. This cross-sectional study investigated the association of this exposure and early renal damage in patients with calcium urolithiasis. We recruited patients diagnosed with upper urinary tract calcium urolithiasis from three hospitals in southwestern Taiwan between November 2010 and January 2015. All patients completed a structured questionnaire and provided one-spot urine samples for the measurement of melamine level and markers of early renal injury, including N-acetyl b-d-glucosaminidase (NAG), β2-microglobulin (β2-MG), and microalbumin...
December 2017: Environmental Pollution
Bingbing Huo, Bingping Liu, Tao Chen, Liang Cui, Gengfang Xu, Mengli Liu, Jingquan Liu
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...
September 29, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Cinthia Alegre, David Sebastián, María E Gálvez, Estela Baquedano, Rafael Moliner, Antonino S Aricò, Vincenzo Baglio, María J Lázaro
Durability and limited catalytic activity are key impediments to the commercialization of polymer electrolyte fuel cells. Carbon materials employed as catalyst support can be doped with different heteroatoms, like nitrogen, to improve both catalytic activity and durability. Carbon xerogels are nanoporous carbons that can be easily synthesized in order to obtain N-doped materials. In the present work, we introduced melamine as a carbon xerogel precursor together with resorcinol for an effective in-situ N doping (3-4 wt % N)...
September 17, 2017: Materials
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