Microwave-assisted synthesis of magnetite nanoparticles possessing superior magnetic properties

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Oleic acid-treated synthesis of MnO@C with superior electrochemical properties

MnO@C nanocomposites are synthesized by annealing MnO microspheres treated with oleic acid as carbon source. The obtained MnO@C nanocomposites exhibit a discharge capacity of 1075 m Ah/g for the initial cycle, and show the excellent cycling performance with a discharge capacity of 421 mAh/g after100 cycles at a current density of 100 mA/g. The total specific capacity of MnO@C nanocomposites is higher than those of pure MnO microspheres in our experiments. Owing to the superior electrochemical behavior, the as-obtained MnO@C nanocomposites are potentially applied as next-generation anode material for lithium-ion batteries.     

Direct synthesis of spatially-controlled Pt-on-Pd bimetallic nanodendrites with superior electrocatalytic activity

Here we report a facile synthesis of Pt-on-Pd bimetallic nanodendrites with a Pd interior and dendritic Pt exterior. The developed route rationally utilizes the spontaneous separation of the depositions of Pd and Pt, which endows direct formation of Pt-on-Pd nanodendrites. This is a truly simple and unique process that is quite different from the traditional seed-mediated growth strategy. Fine-tuning of the Pt and Pd ratios afforded Pt-on-Pd nanodendrites with superior electrocatalytic activity in comparison with commercial Pt electrocatalysts.     

Enzyme electrodes for the sugar substitute aspartame

A sensor of aspartame (l-aspartyl-l-phenylalanine methyl ester) is prepared by chemical immobilization of l-aspartase on an ammonia-selective electrode. Semi logarithmic response (E vs. log C) was observed in the 1 × 10^?3?1 × 10^?2 M range with a slope of ?30 mV/decade. The sensor is stable for more than eight days. The probe is successfully used for the assay of aspartame in commercially available sweeteners.     

A biosensor based on graphite epoxy composite electrode for aspartame and ethanol detection

A gelatin membrane with carboxyl esterase and alcohol oxidase was subsequently integrated onto the surface of a graphite epoxy composite electrode (GECE). The developed biosensors showed linearity in the range of 2.5–400 μM for aspartame and 2.5–25 μM for ethanol with response times of 170 and 70 s for each analyte, respectively. The resulting bienzyme biosensor was used for aspartame detection in diet coke samples and ethanol detection in beer and wine samples. From the obtained results, it can be concluded that the developed biosensor is a selective, practical and economic tool for aspartame and ethanol detection in real samples.     

Enzymatic assay technique for the determination of aspartame

An enzymatic assay technique was developed for the determination of the artificial sweetener aspartame. The peptide bond of aspartame was first cleaved by peptidase to release aspartic acid. In the presence of α-ketoglutarate, aspartic acid was then transaminated by aspartate aminotransferase to glutamate. The reaction was monitored by following the oxygen consumption during the enzymatic oxidation of glutamate by glutamate oxidase. A linear relationship between oxygen consumption and aspartame concentration up to 200 μM was obtained. The assay technique was applicable to the determination of aspartame in a variety of dietary food products. The results obtained agreed well with those determined by liquid chromatography and those reported by the product manufacturers.     

A novel synthesis of Nb_2O_5@rGO nanocomposite as anode material for superior sodium storage

The development of novel anode materials,with superior rate capability,is of utmost significance for the successful realization of sodium-ion batteries(SIBs).Herein,we present a nanocomposite of Nb_2 O_5 and reduced graphene oxide(rGO) by using hydrothermal-assisted microemulsion route.The water-in-oil microemulsion formed nanoreactors,which restrained the particle size of Nb_2 O_5 and shortened the diffusion length of ions.Moreover,the rGO network prevented agglomeration of Nb_2 O_5 nanoparticles and improved electronic conductivity.Consequently,Nb_2 O_5@rGO nanocomposite is employed as anode material in SIBs,delivering a capacity of 195 mAh/g after 200 charge/discharge cycles at 0.2 A/g.Moreover,owing to conductive rGO network,the Nb_2 O_5@rGO electrode rende red a specific capacity of 76 mAh/g at high current density of 10 A/g and maintained 98 mAh/g after 1000 charge/discharge cycles at 2 A/g.The Nb_2 O_5@rGO electrode material prepared by microemulsion method shows promising possibilities for application of SIBs.     

Enzymic method for the spectrophotometric determination of aspartame in beverages

A sensitive spectrophotometric method for the determination of aspartame in beverages is described. The method involves the enzymic conversion of aspartame into formaldehyde by the alpha-chymotrypsin-alcohol oxidase system, followed by the formation of a chromophore with 4-aminopent-3-en-2-one. The calibration graph was linear in the range 2.0-30.0 micrograms ml-1 of aspartame. Many common ingredients of beverages do not interfere with the proposed method. The method was applied to the determination of the aspartame content of various real samples, and the results obtained were compared with those given by high-performance liquid chromatography.     

Ion-pair high-performance liquid chromatographic analysis of aspartame and related products

A simple and accurate quantitative determination of aspartame (L-alpha-aspartyl-L-phenylalanine methyl ester), a new artificial sweetener, is described. The method, which is based on ion-pair high-performance liquid chromatography, allows the determination of aspartame in finished bulk and dosage forms, and the detection of a few related products at levels down to 0.1%.     

Determination of aspartame by ion chromatography with electrochemical integrated amperometric detection

In this paper, the separation and determination of the sweetener aspartame by ion chromatography coupled with electrochemical amperometric detection is reported. Sodium saccharin, acesulfame-K and aspartame were separated using 27.5 mmol/l NaOH isocratic elution on a Dionex IonPac AS4A-SC separation column. Aspartame can be determined by integrated amperometric detection without interference from the other two sweeteners. The method can be applied to the determination of aspartame in powered tabletop, fruit juice and carbonated beverage samples, and the results obtained by integrated amperometry were in agreement with those obtained using a UV detection method. A method for determining analytes with an NH₂ group by ion chromatography with integrated amperometry was developed.     

HPLC analysis of aspartame and saccharin in pharmaceutical and dietary formulations

Summary A reversed-phase HPLC method has been developed suitable for a reliable quality control of pharmaceutical and dietary formulations containing the synthetic sweeteners aspartame and saccharin. The proposed method is able to separate acesulfame, aspartame and saccharin, and their impurities such as 5-benzyl-3,6-dioxo-2-piperazineacetic acid (the major degradation product of aspartame) and 4-sulphamoylbenzoic acid,o- andp-toluenesulphonamides (the synthesis impurities of saccharin). A convenient solid-phase extraction (SPE) procedure using C-18 sorbent, was also developed for the determination of potential saccharin impurities.     

One-pot synthesis of bimetallic Fe/Co incorporated silica hollow spheres with superior peroxidase-like activity

Mesoporous silica hollow spheres with a homogenous and high content distribution of Fe and Co were synthesized by a facile one-pot hydrothermal process. The sub-nanometer bimetallic components inside the silica framework facilitate the stable fixation and the open accessibility to active sites. The co-doped Fe/Co in the spheres showed excellent peroxidase-like activity and much higher catalytic performance than their monometallic-supported spheres. The synergistic effect between Fe and Co promotes the continuous formation of functional radicals during the oxidation process and thus accelerates the reaction rate. When used for colorimetric detection of hydrogen peroxide (H₂O₂), the Fe/Co incorporated silica hollow spheres show the capability of detection of H₂O₂ in a wide range (10-250 µmol/L) and with the low detection limit of 0.012 ppm.     

Facile synthesis of monodisperse porous Co3O4 microspheres with superior ethanol sensing properties

A solvothermal method was developed to prepare on a large scale monodisperse porous β-Co(OH)(2) microspheres consisting of nanoplatelets. Co(3)O(4) microspheres with porous platelets were obtained via subsequent thermal decomposition. These Co(3)O(4) microspheres show much higher ethanol sensitivity and selectivity at a relatively low temperature (135 °C) compared with those of commercial Co(3)O(4) nanoparticles.     

Sustainable synthesis of Penicillium-derived highly conductive carbon film as superior binder-free electrode of lithium ion batteries

Fungi (Penicillium chrysogenum) were used as green and sustainable sources to fabricate free-standing binder-free carbon film through pyrolysis in inert atmosphere. The fungi before and after carbonization were characterized with scanning electron microscope (SEM), Fourier transformed infrared spectroscopy (FTIR), electron microprobe (EM), and Raman spectrum. The results showed that the fungi were composed of ultra-long microfibers around 3 μm in diameter, which can be readily transformed into membrane precursor. Abundant functional groups were detected on fungi. The carbon membrane from the pyrolysis of membrane precursor was constructed by the uniformly interconnected fibers. After carbonization, the functional groups disappeared, while the product was doped by O and N atoms. The conductivity of carbon film was as high as 29.4 S cm^?1. Moreover, the carbon film was successfully applied as low-cost electrode in lithium ion batteries (LIBs). The capacity of the LIBs maintained 207 mA h g^?1 with 89.6 % capacity retention after 80 cycles.