Ultra-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC-HRMS/MS) was employed to investigate the inhibitory mechanism of quercetin against the formation of 5-(hydroxymethyl)-2-furaldehyde (HMF) in buckwheat flour bread. The HMF and HMF precursors (3,4-dideoxyglucosone-3-ene (3,4-DGE), 3-deoxyglucosone (3-DG), or fructofuranosyl cation dehydration products (FCDPs)) adducts of quercetin were detected in buckwheat flour bread, with the trapping of these compounds by quercetin to form corresponding adducts with HMF or its precursors in 1:1, 1:2, 1:3, and 1:4 ratios (where "1" refers to quercetin in all cases). The structures of these adducts were elucidated by UPLC-HRMS/MS. Carbohydrate module labeling (CAMOLA) techniques and the labelled quercetin in model reactions were utilized to further confirm the inhibitory mechanism. Effects of baking temperature and time on the HMF inhibition rate were investigated in wheat flour bread, and a maximum inhibition rate of 86.0% was obtained with the baking of wheat flour bread (with the added quercetin concentration of 1.90mg/g) at 160°C for 30min.

However, ionic liquids tend to separate from the activated carbon when exposed to water even for a relatively short period.RESULTS: Characterization of spherical activated carbon (SAC) modified with poly(1-vinyl-3-butylimidazolium hexafluorophosphate) (PIL) showed that 1-vinyl-3-butylimidazolium hexafluorophosphate (IL) was adsorbed and polymerized on SAC. Stability studies of PIL-SAC in water demonstrated that it was more stable against IL desorption in water than the non-polymerized IL-SAC. The adsorption data showed that the modification improved the adsorption capacity of SAC at least 2-fold. The results also indicated that although the pH and ionic strength of the solution played a significant role in the adsorption process, there was no significant influence on the adsorption capacity. Moreover, PIL-SAC could be reused at least five times with only minor losses in its adsorption capacity.CONCLUSION: The activated carbon modified with PIL produces a remarkable increase in the ibuprofen adsorption capacity and strongly decreases undesirable desorption of ionic liquids. (C) 2015 Society of Chemical Industry

For increasing active ingredients accessibility to the solvents, microwave assisted ionic liquid pretreatment (MILP) is introduced to destroy cell walls of medicinal plants before solvent extraction. As a new sample pretreatment method, microwave irradiation on sample pretreatment with ionic liquids (ILs) was investigated. The conditions of MILP including microwave pretreatment time and power, ionic liquid (IL) and sample ratio and particle size were optimized and Cynanchum paniculatum and its active ingredient paeonol were chosen as the representative target analyte. Under the optimized conditions, the paeonol extraction yield by MILP was higher than that of ionic liquid aqueous solution and Soxhlet extraction. In addition, the results of bioassay test showed that the antibacterial effect of crude extract by MILP was almost the same with that of soxhlet extraction. Our results demonstrate that sample pretreatment with ILs and microwave irradiation is a potential alternative method for the pretreatment of medicinal plants before solvent extraction. (C) 2011 Elsevier B.V. All rights reserved.

Co-doped Li3V2−xCox(PO4)3/C (x = 0.00, 0.03, 0.05, 0.10, 0.13 or 0.15) compounds were prepared via a solid-state reaction. The Rietveld refinement results indicated that single-phase Li3V2−xCox(PO4)3/C (0 ≤ x ≤ 0.15) with a monoclinic structure was obtained. The X-ray photoelectron spectroscopy (XPS) analysis revealed that the cobalt is present in the +2 oxidation state in Li3V2−xCox(PO4)3. XPS studies also revealed that V4+ and V3+ ions were present in the Co2+-doped system. The initial specific capacity decreased as the Co-doping content increased, increasing monotonically with Co content for x > 0.10. Differential capacity curves of Li3V2−xCox(PO4)3/C compounds showed that the voltage peaks associated with the extraction of three Li+ ions shifted to higher voltages with an increase in Co content, and when the Co2+-doping content reached 0.15, the peak positions returned to those of the unsubstituted Li3V2(PO4)3 phase. For the Li3V1.85Co0.15(PO4)3/C compound, the initial capacity was 163.3 mAh/g (109.4% of the initial capacity of the undoped Li3V2(PO4)3) and 73.4% capacity retention was observed after 50 cycles at a 0.1 C charge/discharge rate. The doping of Co2+into V sites should be favorable for the structural stability of Li3V2−xCox(PO4)3/C compounds and so moderate the volume changes (expansion/contraction) seen during the reversible Li+ extraction/insertion, thus resulting in the improvement of cell cycling ability.

Single-phase lithium manganese borate, LiMnBO3, was obtained at the temperature higher than 850°C by one-step solid state reaction without using carbon black in the starting materials. The initial specific discharge capacity for the cathode active material was 75.5mAh/g at the current density of 5mA/g and the mean fade of capacity was 0.09% per cycle except for the first cycle. The LiMnBO3 compound maintained a specific discharge capacity of 42.3mAh/g even at the current density of 50mA/g and the capacity fade per cycle was only 0.2% during 40 cycles. The cyclic voltammograms (CV) curves show that the Mn3+/Mn2+ redox couple situated at 2.23 and 4.13V can be clearly observed during anodic and cathodic sweeps. Combined the cyclic voltammograms results with the X-ray diffraction patterns of electrodes before and after cycling, where no significant change of the peak currents and the peak potentials during cycling, it was anticipated that the extraction and insertion of Li-ions are totally reversible in this compounds and the hexagonal structure for LiMnBO3 can be maintained after long cycles under high charge and discharge rate.

Cr-doped Li3V2−xCrx(PO4)3/C (x=0, 0.05, 0.1, 0.2, 0.5, 1) compounds have been prepared using sol–gel method. The Rietveld refinement results indicate that single-phase Li3V2−xCrx(PO4)3/C with monoclinic structure can be obtained. Although the initial specific capacity decreased with Cr content at a lower current rate, both cycle performance and rate capability have excited improvement with moderate Cr-doping content in Li3V2−xCrx(PO4)3/C. Li3V1.9Cr0.1(PO4)3/C compound presents an initial capacity of 171.4mAhg−1 and 78.6% capacity retention after 100 cycles at 0.2C rate. At 4C rate, the Li3V1.9Cr0.1(PO4)3/C can give an initial capacity of 130.2mAhg−1 and 10.8% capacity loss after 100 cycles where the Li3V2(PO4)3/C presents the initial capacity of 127.4mAhg−1 and capacity loss of 14.9%. Enhanced rate and cyclic capability may be attributed to the optimizing particle size, carbon coating quality, and structural stability during the proper amount of Cr-doping (x=0.1) in V sites.

A liquid-based sol–gel method was developed to synthesize nanocarbon-coated Li3V2(PO4)3. The products were characterized by XRD, SEM and electrochemical measurements. The results of Rietveld refinement analysis indicate that single-phase Li3V2(PO4)3 with monoclinic structure can be obtained in our experimental process. The discharge capacity of carbon-coated Li3V2(PO4)3 was 152.6 mAh/g at the 50th cycle under 1C rate, with 95.4% retention rate of initial capacity. A high discharge capacity of 184.1 mAh/g can be obtained under 0.12C rate, and a capacity of 140.0 mAh/g can still be held at 3C rate. The cyclic voltammetric measurements indicate that the electrode reaction reversibility is enhanced due to the carbon-coating. SEM images show that the reduced particle size and well-dispersed carbon-coating can be responsible for the good electrochemical performance obtained in our experiments.

Monoclinic lithium vanadium phosphate, Li3V2(PO4)3, has been successfully synthesized using LiF as lithium source. The one-step reaction with stoichiometric composition and relative lower sintering temperature (700 °C) has been used in our experimental processes. The solid-state reaction mechanism using LiF as lithium precursor has been studied by X-ray diffraction and Fourier transform infrared spectra. The Rietveld refinement results show that in our product sintered at 700 °C no impurity phases of VPO4, Li5V(PO4)2F2, or LiVPO4F can be detected. The solid-state reaction using Li2CO3 as Li-precursor has also been carried out for comparison. X-ray diffraction patterns indicate that impurities as Li3PO4 can be found in the product using Li2CO3 as Li-precursor unless the sintering temperatures are higher than 850 °C. An abrupt particle growth (about 2 μm) has also been observed by scanning electron microscope for the samples sintered at higher temperatures, which can result in a poor cycle performance. The product obtained using LiF as Li-precursor with the uniform flake-like particles and smaller particle size (about 300 nm) exhibits the better performance. At the 50th cycle, the reversible specific capacities for Li3V2(PO4)3 measured between 3 and 4.8 V at 1C rate are found to approach 147.1 mAh/g (93.8% of initial capacity). The specific capacity of 123.6 mAh/g can even be hold between 3 and 4.8 V at 5C rate.

Monoclinic Li3V2(PO4)3 can be synthesized by solid-state reaction using either hydrogen or carbon as the reducing agent when sintering temperatures are higher than 800°C. The initial capacity of Li3V2(PO4)3 synthesized using hydrogen as the reducing agent increases with increasing sintering temperature T and then for T>900°C decreases monotonically, and the sample synthesized at 900°C present the highest initial capacity of 146.3mAhg−1, but exhibit poor cycle performance. The scanning electron microscope (SEM) images show that Li3V2(PO4)3 particles with small uniform particle size can be obtained at 900°C. X-ray diffraction patterns of electrodes before and after cycling indicate that the capacity fading is not related to structure collapse. The carbon-coated Li3V2(PO4)3 (LVP/C) composites are synthesized by carbo-thermal reduction method at the optimized temperature of 900°C. The LVP/C exhibit good cycle performance (137.5mAhg−1 at 50th cycle under 1C rate, 94.6% of initial discharge capacity) and rate behavior (111.0mAhg−1 under 5C rate for initial discharge) for the fully de-lithiated (3–4.8V) samples. Our results suggest, based on the SEM images, that the good capacity retention and rate performance are owing to the nanometer size carbon webs coated the Li3V2(PO4)3 particles with both the greater specific surface area and the small uniform particle size.

以纳米碳粒子为原料,用化学表面修饰技术使纳米碳粒子表面功能化,将乙二氨基、氨荒酸基、硫脲基、脒基等官能团以共价键方式偶联在纳米碳粒的表面,制备出不同类型的纳米高分子络合吸附剂.吸附剂的粒径为4～8 nm,功能团在纳米碳粒子的表面含量为1.1 mmol/g.纳米高分子络合剂对过渡金属离子的吸附速率高、吸附量大并具有很高的选择性.

The effects of reaction conditions on the redox absorption of Ce4+ onto viscose-based activated carbon fiber felt (VACF) were investigated in this work. The results show that although few cerium ions are absorbed on VACF, the reduction capacity of VACF towards Ce4+ is high and strongly depends on the concentration of Ce4+ , the ratio of solid/liquid, the pH value and the reaction temperature, etc. These factors can be interpreted by Nernst equation. After oxidation, the specific surface area and pore volume of VACF significantly decrease, but the total surface oxygen content is greatly improved. With increasing oxidant concentration, the redox capacity of VACF is enhanced. However, the O/C ratio on the surface of VACF is not changed obviously because the formation and releasing of CO2 increases at the same time.

Ethylenediamine, dithiocarbamate and thioureido ligand functionalized nanoparticles, with average diameters ranging from 4 to 8 nm and containing 1.06 to 1.26 mmol of ligand/g, are readily obtained when carbon nanobeads are modified with a silane coupling agent,and then functionalized with carbon disulfide and phenylisothiocyanate. Their sorption characteristics for transition metal cations have been studied. The nanometer metal ion adsorbents exhibit very high selectivities, capacities and rates of complexing. This study demonstrates that these nanoparticles have potential applications as catalyst supports.

Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent on activated carbon fiber strongly affects adsorption capacity of activated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three times by the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended on the pH value of adsorption and temperature.