Execution, assessment and improvement methods of motor imagery for brain-computer interface / 生物医学工程学杂志

Motor imagery (MI) is an important paradigm of driving brain computer interface (BCI). However, MI is not easy to control or acquire, and the performance of MI-BCI depends heavily on the performance of the subjects' MI. Therefore, the correct execution of MI mental activities, ability evaluation and improvement methods play important and even critical roles in the improvement and application of MI-BCI system's performance. However, in the research and development of MI-BCI, the existing researches mainly focus on the decoding algorithm of MI, but do not pay enough attention to the above three aspects of MI mental activities. In this paper, these problems of MI-BCI are discussed in detail, and it is pointed out that the subjects tend to use visual motor imagery as kinesthetic motor imagery. In the future, we need to develop some objective, quantitatively visualized MI ability evaluation methods, and develop some effective and less time-consumption training methods to improve MI ability. It is also necessary to solve the differences and commonness of MI problems between and within individuals and MI-BCI illiteracy to a certain extent.

Effect of graphene oxide on the function of erythrocytes / 生物工程学报

The biocompatibility of nanomaterials has attracted much attention. Graphene oxide (GO) is a nanomaterial widely used in biomedicine, but its toxicity can not be ignored. In this study, the effect of GO on the blood system (the hemolysis rate, the fragility of erythrocyte, and acetylcholinesterase activity) was systematically investigated. The results showed that the hemolysis rate of erythrocytes was lower than 8% when the GO concentration was below 100 μg/mL (P5 μm (LGO) increased the activity of acetylcholinesterase by 42.67% (P<0.05). Then molecular dynamics simulation was used to study how GO interacted with acetylcholinesterase and increased its activity. The results showed that GO was attached to the cell membrane, thus may provide an electronegative environment that helps the hydrolysate to detach from the active sites more quickly so as to enhance the activity of acetylcholinesterase.

Evaluation of Orchid-Like Aroma Between Different Grades of Taiping Houkui Tea by Solid-Phase Microextraction and Comprehensive Two-Dimensional Gas Chromatography Coupled with Time-of-Fight Mass Spectrometry.

BACKGROUND: Taiping houkui tea won the title of "the King of Green Tea" at the International Tea Exposition in 2004, which had an orchid fragrance but the material basis of the orchid fragrance had not been revealed yet. OBJECTIVE: To investigate the material basis of the orchid fragrance and identify the quality grade of Taiping houkui tea. METHODS: A method was developed for evaluating orchid-like aroma between different grades Taiping houkui tea by solid-phase micro extraction (SPME) and comprehensive two-dimensional gas chromatography coupled with time-of-fight mass spectrometry (GC×GC-TOFMS). The crushed tea sample in a 25 mL headspace bottle was incubated at 90°C for 10 min. Then the gaseous sample was extracted by SPME divinylbenzene/polydimethylsiloxane fiber for 50 min and thermally desorpted at 250°C for 2 min. RESULTS: In total, 735 volatile compounds were determined by SPME- GC×GC-TOFMS and 15 compounds were related to orchid-like aroma. CONCLUSIONS: The high-quality Taiping houkui tea has the orchid fragrance and the low-grade one does not; thus orchid-like aroma can be used as a reference of grades of Taiping houkui tea. HIGHLIGHTS: Thirty different grades of Taiping houkui tea samples were compared and analyzed experimentally, and the results showed that the special aroma substances, which played a key role in grade discrimination of Taiping houkui tea, were found by the statistical method.

Microwave-Assisted Extraction Combined with Ultra-High-Performance Liquid Chromatography and Quadrupole/Q-Exactive High-Resolution Mass Spectrometry for the Determination of Main Flavor Substances in Green Tea.

BACKGROUND: In order to make up for the efficacy of sensory assessment of green tea quality and taste, main flavor substances should be quantitatively characterized based on efficient extraction and frontier determination scheme. METHODS: A new, relatively simple sample preparation and detection workflow has been developed for the quantification and confirmation of flavor substances in green tea by microwave-assisted extraction combined with ultra-high-performance LC and quadrupole/Q-Exactive high-resolution MS system. The method identified main flavor substances (i.e., catechins, free amino acids, and caffeine) that were the main components in the formation of tea taste. After crushing pretreatment, tea was extracted and purified simultaneously in a microwave extraction jar by matrix-dispersed solid-phase extraction. The extracting solution was determined by LC coupled to high-resolution Orbitrap mass spectrometry. RESULTS: In this study, extraction solvent and purification materials were selected, extraction temperature and time were optimized, and the amount and proportion of solid-phase extraction packing were optimized. CONCLUSIONS: The method enabled detection of multiple catechins, amino acids, and caffeine in tea by LC coupled to high-resolution Orbitrap MS, and a database of tea flavor substances was established. HIGHLIGHTS: The method could be used for screening and confirmation of the main flavor substances in tea as well as assisting the sensory evaluation to grade the quality of tea.

Simultaneous Determination of 16 Carcinogenic and Allergenous Dyestuffs in Toys by Ultra Performance Liquid Chromatography Tandem Mass Spectrometry / 分析化学

A comprehensive analytical method based on ultra performance liquid chromatography tandem mass spectrometry has been developed for the simultaneous determination of 16 carcinogenic and allergenous dye stuffs (acid red 26, basic red 9, disperse blue 1, acid violet 49, disperse blue 3, solvent yellow 1, dispersed blue 106, disperse orange 3, disperse yellow 3, basic violet 1, basic violet 3, disperse red 1, solvent yellow 3, disperse blue 124, solvent yellow 2 and disperse orange 37).Various toy samples, including textile, leath er, paper, wood, balloon, modeling clay, limitation tattoo and aqueous liquid, were extracted under ultrason ication.Qualitative and quantitative analysis was carried out for the analyte under the MRM mode after the chromatographic separation on Waters ACQUITY UPLC BEH C_(18)(50 mm x 2.1 mm, 1.7 μm) column.The limits of quantitation(LOQ) for the 16 dyestuffs were in the range of 1.0-8.0 μg/kg.The mean recoveries at the three spiked levels of 5-100 μg/kg were 81.3%-98.6%, with the intra-day precision less than 11% and the inter-day precision less than 14%.The method is accurate, rapid, sensitive, and adapt to the inspec tion of the 16 dyestuffs in toys.

Determination of Musk Xylene in Cosmetics by Solid Phase Extraction-Isotope Dilution-Gas Chromatography Tandem Mass Spectrometry / 分析化学

A comprehensive analytical method based on solid phase extraction-isotope dilution-gas chromatography tandem mass spectrometry has been developed for the determination of musk xylene in cosmetics. Various cosmetic samples, including cream, lotion, powder, shampoo and lipstick, were extracted under ultrasonication. The extract was centrifuged, and the upper solution was concentrated by rotary evaporator. The reconstructed solution was then cleaned up by Sep-Pak Silica solid phase extraction cartridge. Qualitative and quantitative analysis was carried out under the MRM mode after the chromatographic separation on DB-5 MS(30 m×0.25 mm, 0.25 μm) capillary column. The limit of quantitation(LOQ) for musk xylene was 5 μg/kg. The mean recoveries at the three spiked levels of 5-50 μg/kg were 81.1%-86.9%, with the intra-day precision less than 10% and the inter-day precision less than 12%. The method is accurate, rapid, sensitive and adapt to the inspection of musk xylene in cosmetics.