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The synthesis of 2,5-diformylfuran (DFF) from fructose is a simultaneous process using two distinct catalysts, including fructose dehydration to 5-hydroxymethylfurfural (5-HMF) accelerated by an acid catalyst, followed by 5-HMF oxidation to DFF mediated by a redox catalyst. In this study, various catalysts with Ag metal decorated on sulfonated amorphous carbon supports (AC-SO 3 H@Ag) were performed, and their structures were characterized via different characterization techniques such as X-ray diffraction, scanning electron microscopy, X-ray fluorescence spectroscopy, thermogravimetric analysis, Boehm's titration, inductively coupled plasma mass spectroscopy, energy-dispersive X-ray spectroscopy, elemental mapping analysis and Fourier-transform infrared spectroscopy. The catalytic performance of the prepared AC-SO 3 H@Ag bifunctional catalysts with various wt% of Ag/AC-SO 3 H was determined for the one-pot transformation of fructose into DFF. The influence of solvent, substrates, reaction time, and catalyst loading were also examined thoroughly to optimize the reaction, and a mechanism was proposed. 5-HMF formed by the dehydration of fructose was converted entirely to DFF, and the highest DFF yield of 77.9 % was obtained after 18 h of reaction time at 150 °C in dimethyl sulfoxide with 3 wt% of the AC-SO 3 H@Ag catalyst and without the use of any additives, traditional hydrogen acceptors, or oxidants. The reusability of the catalysts was also tested. [ABSTRACT FROM AUTHOR]

The screening and monitoring of residual antibiotics in pork meat were conducted in Ho Chi Minh City, Vietnam, from 2014 to 2015. One hundred samples collected from a wholesale market were screened on-site using a microbiological kit, and eighteen samples were determined as positive for residual antibiotics. Once transferred to the lab, all the samples were analyzed for 28 antibiotics using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Sulfamethazine residues (11–1600 μg/kg) were detected in 23 samples by LC-MS/MS. Notably, 11 samples with sulfamethazine concentrations ranging from 310 to 1600 μg/kg were detected as “positive” in the initial screening, whereas 12 other samples with sulfamethazine levels below 200 μg/kg were screened as “negative”. No other targeted antibiotics were identified among the remaining positive samples. These results show the potential and limitations of a monitoring system combining on-site microbiological tests and an LC-MS/MS method. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI)- and multi-walled carbon nanotubes (MWCNTs)-intercalated reduced graphene oxide (rGO) aerogel or PANI/MWCNTs/rGO aerogel (PCGA) was prepared using a one-step hydrothermal co-assembly method for supercapacitor applications. The prepared aerogel exhibited an outstanding porous structure, and showed excellent capacitive performance. PANI and the MWCNTs were dispersed well on the graphene walls of the aerogels and spaced inner graphene layers to encourage electrolyte ion absorption. Accordingly, the specific capacitance of the PCGA was increased to 987 F/g at a scan rate of 0.5 A/g, which strongly surpassed that of the MWCNT/rGO aerogel (CGA) and PANI/rGO aerogel (PGA) with a specific capacitance of 335 and 643 F/g, respectively. PCGA also showed long term cycling stability (94% after 1000 cycles), which is promising as a potential electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

The pilot overhead provides fundamental limits on the performance of massive multiple-input multiple-output (MIMO) systems. This is because the performance of such systems is based on the failure of the presentation of accurate channel state information (CSI). Based on the theory of compressive sensing, this paper presents a novel channel estimation technique as the mean of minimizing the problems associated with pilot overhead. The proposed technique is based on the combination of the compressive sampling matching and sparsity adaptive matching pursuit techniques. The sources of the signals in MIMO systems are sparsely distributed in terms of spatial correlations. This distribution pattern enables then use of compressive sampling techniques to solve the channel estimation problem in MIMO systems. Simulation results demonstrate that the proposed channel estimation outperforms the conventional compressive sensing (CS)-based channel estimation algorithms in terms of the normalized mean square error (NMSE) performance at high signal-to-noise ratios (SNRs). Furthermore, it reduces the computational complexity of the channel estimation compared to conventional methods. In addition to the achieved performance gain in terms of NMSE, the presented method significantly reduces pilot overhead compared to conventional channel estimation techniques. [ABSTRACT FROM AUTHOR]